From 93f7378734b595fb61e89b802002fb7e3a1267d2 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 1 Nov 2023 20:37:45 -0700 Subject: bpf: derive smin/smax from umin/max bounds Add smin/smax derivation from appropriate umin/umax values. Previously the logic was surprisingly asymmetric, trying to derive umin/umax from smin/smax (if possible), but not trying to do the same in the other direction. A simple addition to __reg64_deduce_bounds() fixes this. Added also generic comment about u64/s64 ranges and their relationship. Hopefully that helps readers to understand all the bounds deductions a bit better. Acked-by: Eduard Zingerman Acked-by: Shung-Hsi Yu Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231102033759.2541186-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 71 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index bd1c42eb540f..1a5c389b951a 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2358,6 +2358,77 @@ static void __reg32_deduce_bounds(struct bpf_reg_state *reg) static void __reg64_deduce_bounds(struct bpf_reg_state *reg) { + /* If u64 range forms a valid s64 range (due to matching sign bit), + * try to learn from that. Let's do a bit of ASCII art to see when + * this is happening. Let's take u64 range first: + * + * 0 0x7fffffffffffffff 0x8000000000000000 U64_MAX + * |-------------------------------|--------------------------------| + * + * Valid u64 range is formed when umin and umax are anywhere in the + * range [0, U64_MAX], and umin <= umax. u64 case is simple and + * straightforward. Let's see how s64 range maps onto the same range + * of values, annotated below the line for comparison: + * + * 0 0x7fffffffffffffff 0x8000000000000000 U64_MAX + * |-------------------------------|--------------------------------| + * 0 S64_MAX S64_MIN -1 + * + * So s64 values basically start in the middle and they are logically + * contiguous to the right of it, wrapping around from -1 to 0, and + * then finishing as S64_MAX (0x7fffffffffffffff) right before + * S64_MIN. We can try drawing the continuity of u64 vs s64 values + * more visually as mapped to sign-agnostic range of hex values. + * + * u64 start u64 end + * _______________________________________________________________ + * / \ + * 0 0x7fffffffffffffff 0x8000000000000000 U64_MAX + * |-------------------------------|--------------------------------| + * 0 S64_MAX S64_MIN -1 + * / \ + * >------------------------------ -------------------------------> + * s64 continues... s64 end s64 start s64 "midpoint" + * + * What this means is that, in general, we can't always derive + * something new about u64 from any random s64 range, and vice versa. + * + * But we can do that in two particular cases. One is when entire + * u64/s64 range is *entirely* contained within left half of the above + * diagram or when it is *entirely* contained in the right half. I.e.: + * + * |-------------------------------|--------------------------------| + * ^ ^ ^ ^ + * A B C D + * + * [A, B] and [C, D] are contained entirely in their respective halves + * and form valid contiguous ranges as both u64 and s64 values. [A, B] + * will be non-negative both as u64 and s64 (and in fact it will be + * identical ranges no matter the signedness). [C, D] treated as s64 + * will be a range of negative values, while in u64 it will be + * non-negative range of values larger than 0x8000000000000000. + * + * Now, any other range here can't be represented in both u64 and s64 + * simultaneously. E.g., [A, C], [A, D], [B, C], [B, D] are valid + * contiguous u64 ranges, but they are discontinuous in s64. [B, C] + * in s64 would be properly presented as [S64_MIN, C] and [B, S64_MAX], + * for example. Similarly, valid s64 range [D, A] (going from negative + * to positive values), would be two separate [D, U64_MAX] and [0, A] + * ranges as u64. Currently reg_state can't represent two segments per + * numeric domain, so in such situations we can only derive maximal + * possible range ([0, U64_MAX] for u64, and [S64_MIN, S64_MAX] for s64). + * + * So we use these facts to derive umin/umax from smin/smax and vice + * versa only if they stay within the same "half". This is equivalent + * to checking sign bit: lower half will have sign bit as zero, upper + * half have sign bit 1. Below in code we simplify this by just + * casting umin/umax as smin/smax and checking if they form valid + * range, and vice versa. Those are equivalent checks. + */ + if ((s64)reg->umin_value <= (s64)reg->umax_value) { + reg->smin_value = max_t(s64, reg->smin_value, reg->umin_value); + reg->smax_value = min_t(s64, reg->smax_value, reg->umax_value); + } /* Learn sign from signed bounds. * If we cannot cross the sign boundary, then signed and unsigned bounds * are the same, so combine. This works even in the negative case, e.g. -- cgit v1.2.3 From d540517990a9d105bf0312760665964916ac044f Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 1 Nov 2023 20:37:46 -0700 Subject: bpf: derive smin32/smax32 from umin32/umax32 bounds All the logic that applies to u64 vs s64, equally applies for u32 vs s32 relationships (just taken in a smaller 32-bit numeric space). So do the same deduction of smin32/smax32 from umin32/umax32, if we can. Acked-by: Eduard Zingerman Acked-by: Shung-Hsi Yu Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231102033759.2541186-5-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 1a5c389b951a..b53ee72a7d72 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2324,6 +2324,13 @@ static void __update_reg_bounds(struct bpf_reg_state *reg) /* Uses signed min/max values to inform unsigned, and vice-versa */ static void __reg32_deduce_bounds(struct bpf_reg_state *reg) { + /* if u32 range forms a valid s32 range (due to matching sign bit), + * try to learn from that + */ + if ((s32)reg->u32_min_value <= (s32)reg->u32_max_value) { + reg->s32_min_value = max_t(s32, reg->s32_min_value, reg->u32_min_value); + reg->s32_max_value = min_t(s32, reg->s32_max_value, reg->u32_max_value); + } /* Learn sign from signed bounds. * If we cannot cross the sign boundary, then signed and unsigned bounds * are the same, so combine. This works even in the negative case, e.g. -- cgit v1.2.3 From c1efab6468fd5ef541d47d81dbb62cca27f8db3b Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 1 Nov 2023 20:37:47 -0700 Subject: bpf: derive subreg bounds from full bounds when upper 32 bits are constant Comments in code try to explain the idea behind why this is correct. Please check the code and comments. Acked-by: Eduard Zingerman Acked-by: Shung-Hsi Yu Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231102033759.2541186-6-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index b53ee72a7d72..9e39f12538f7 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2324,6 +2324,51 @@ static void __update_reg_bounds(struct bpf_reg_state *reg) /* Uses signed min/max values to inform unsigned, and vice-versa */ static void __reg32_deduce_bounds(struct bpf_reg_state *reg) { + /* If upper 32 bits of u64/s64 range don't change, we can use lower 32 + * bits to improve our u32/s32 boundaries. + * + * E.g., the case where we have upper 32 bits as zero ([10, 20] in + * u64) is pretty trivial, it's obvious that in u32 we'll also have + * [10, 20] range. But this property holds for any 64-bit range as + * long as upper 32 bits in that entire range of values stay the same. + * + * E.g., u64 range [0x10000000A, 0x10000000F] ([4294967306, 4294967311] + * in decimal) has the same upper 32 bits throughout all the values in + * that range. As such, lower 32 bits form a valid [0xA, 0xF] ([10, 15]) + * range. + * + * Note also, that [0xA, 0xF] is a valid range both in u32 and in s32, + * following the rules outlined below about u64/s64 correspondence + * (which equally applies to u32 vs s32 correspondence). In general it + * depends on actual hexadecimal values of 32-bit range. They can form + * only valid u32, or only valid s32 ranges in some cases. + * + * So we use all these insights to derive bounds for subregisters here. + */ + if ((reg->umin_value >> 32) == (reg->umax_value >> 32)) { + /* u64 to u32 casting preserves validity of low 32 bits as + * a range, if upper 32 bits are the same + */ + reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)reg->umin_value); + reg->u32_max_value = min_t(u32, reg->u32_max_value, (u32)reg->umax_value); + + if ((s32)reg->umin_value <= (s32)reg->umax_value) { + reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->umin_value); + reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->umax_value); + } + } + if ((reg->smin_value >> 32) == (reg->smax_value >> 32)) { + /* low 32 bits should form a proper u32 range */ + if ((u32)reg->smin_value <= (u32)reg->smax_value) { + reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)reg->smin_value); + reg->u32_max_value = min_t(u32, reg->u32_max_value, (u32)reg->smax_value); + } + /* low 32 bits should form a proper s32 range */ + if ((s32)reg->smin_value <= (s32)reg->smax_value) { + reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->smin_value); + reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->smax_value); + } + } /* if u32 range forms a valid s32 range (due to matching sign bit), * try to learn from that */ -- cgit v1.2.3 From 6593f2e6741f03b49bffc9d55ddd4c1c47853c39 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 1 Nov 2023 20:37:48 -0700 Subject: bpf: add special smin32/smax32 derivation from 64-bit bounds Add a special case where we can derive valid s32 bounds from umin/umax or smin/smax by stitching together negative s32 subrange and non-negative s32 subrange. That requires upper 32 bits to form a [N, N+1] range in u32 domain (taking into account wrap around, so 0xffffffff to 0x00000000 is a valid [N, N+1] range in this sense). See code comment for concrete examples. Eduard Zingerman also provided an alternative explanation ([0]) for more mathematically inclined readers: Suppose: . there are numbers a, b, c . 2**31 <= b < 2**32 . 0 <= c < 2**31 . umin = 2**32 * a + b . umax = 2**32 * (a + 1) + c The number of values in the range represented by [umin; umax] is: . N = umax - umin + 1 = 2**32 + c - b + 1 . min(N) = 2**32 + 0 - (2**32-1) + 1 = 2, with b = 2**32-1, c = 0 . max(N) = 2**32 + (2**31 - 1) - 2**31 + 1 = 2**32, with b = 2**31, c = 2**31-1 Hence [(s32)b; (s32)c] forms a valid range. [0] https://lore.kernel.org/bpf/d7af631802f0cfae20df77fe70068702d24bbd31.camel@gmail.com/ Acked-by: Eduard Zingerman Acked-by: Shung-Hsi Yu Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231102033759.2541186-7-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9e39f12538f7..0fffbf01328e 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2369,6 +2369,29 @@ static void __reg32_deduce_bounds(struct bpf_reg_state *reg) reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->smax_value); } } + /* Special case where upper bits form a small sequence of two + * sequential numbers (in 32-bit unsigned space, so 0xffffffff to + * 0x00000000 is also valid), while lower bits form a proper s32 range + * going from negative numbers to positive numbers. E.g., let's say we + * have s64 range [-1, 1] ([0xffffffffffffffff, 0x0000000000000001]). + * Possible s64 values are {-1, 0, 1} ({0xffffffffffffffff, + * 0x0000000000000000, 0x00000000000001}). Ignoring upper 32 bits, + * we still get a valid s32 range [-1, 1] ([0xffffffff, 0x00000001]). + * Note that it doesn't have to be 0xffffffff going to 0x00000000 in + * upper 32 bits. As a random example, s64 range + * [0xfffffff0fffffff0; 0xfffffff100000010], forms a valid s32 range + * [-16, 16] ([0xfffffff0; 0x00000010]) in its 32 bit subregister. + */ + if ((u32)(reg->umin_value >> 32) + 1 == (u32)(reg->umax_value >> 32) && + (s32)reg->umin_value < 0 && (s32)reg->umax_value >= 0) { + reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->umin_value); + reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->umax_value); + } + if ((u32)(reg->smin_value >> 32) + 1 == (u32)(reg->smax_value >> 32) && + (s32)reg->smin_value < 0 && (s32)reg->smax_value >= 0) { + reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->smin_value); + reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->smax_value); + } /* if u32 range forms a valid s32 range (due to matching sign bit), * try to learn from that */ -- cgit v1.2.3 From c51d5ad6543cc36334ef1fcd762d0df767a0bf7e Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 1 Nov 2023 20:37:49 -0700 Subject: bpf: improve deduction of 64-bit bounds from 32-bit bounds Add a few interesting cases in which we can tighten 64-bit bounds based on newly learnt information about 32-bit bounds. E.g., when full u64/s64 registers are used in BPF program, and then eventually compared as u32/s32. The latter comparison doesn't change the value of full register, but it does impose new restrictions on possible lower 32 bits of such full registers. And we can use that to derive additional full register bounds information. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Acked-by: Shung-Hsi Yu Link: https://lore.kernel.org/r/20231102033759.2541186-8-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 0fffbf01328e..969f1ecfe310 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2536,10 +2536,54 @@ static void __reg64_deduce_bounds(struct bpf_reg_state *reg) } } +static void __reg_deduce_mixed_bounds(struct bpf_reg_state *reg) +{ + /* Try to tighten 64-bit bounds from 32-bit knowledge, using 32-bit + * values on both sides of 64-bit range in hope to have tigher range. + * E.g., if r1 is [0x1'00000000, 0x3'80000000], and we learn from + * 32-bit signed > 0 operation that s32 bounds are now [1; 0x7fffffff]. + * With this, we can substitute 1 as low 32-bits of _low_ 64-bit bound + * (0x100000000 -> 0x100000001) and 0x7fffffff as low 32-bits of + * _high_ 64-bit bound (0x380000000 -> 0x37fffffff) and arrive at a + * better overall bounds for r1 as [0x1'000000001; 0x3'7fffffff]. + * We just need to make sure that derived bounds we are intersecting + * with are well-formed ranges in respecitve s64 or u64 domain, just + * like we do with similar kinds of 32-to-64 or 64-to-32 adjustments. + */ + __u64 new_umin, new_umax; + __s64 new_smin, new_smax; + + /* u32 -> u64 tightening, it's always well-formed */ + new_umin = (reg->umin_value & ~0xffffffffULL) | reg->u32_min_value; + new_umax = (reg->umax_value & ~0xffffffffULL) | reg->u32_max_value; + reg->umin_value = max_t(u64, reg->umin_value, new_umin); + reg->umax_value = min_t(u64, reg->umax_value, new_umax); + /* u32 -> s64 tightening, u32 range embedded into s64 preserves range validity */ + new_smin = (reg->smin_value & ~0xffffffffULL) | reg->u32_min_value; + new_smax = (reg->smax_value & ~0xffffffffULL) | reg->u32_max_value; + reg->smin_value = max_t(s64, reg->smin_value, new_smin); + reg->smax_value = min_t(s64, reg->smax_value, new_smax); + + /* if s32 can be treated as valid u32 range, we can use it as well */ + if ((u32)reg->s32_min_value <= (u32)reg->s32_max_value) { + /* s32 -> u64 tightening */ + new_umin = (reg->umin_value & ~0xffffffffULL) | (u32)reg->s32_min_value; + new_umax = (reg->umax_value & ~0xffffffffULL) | (u32)reg->s32_max_value; + reg->umin_value = max_t(u64, reg->umin_value, new_umin); + reg->umax_value = min_t(u64, reg->umax_value, new_umax); + /* s32 -> s64 tightening */ + new_smin = (reg->smin_value & ~0xffffffffULL) | (u32)reg->s32_min_value; + new_smax = (reg->smax_value & ~0xffffffffULL) | (u32)reg->s32_max_value; + reg->smin_value = max_t(s64, reg->smin_value, new_smin); + reg->smax_value = min_t(s64, reg->smax_value, new_smax); + } +} + static void __reg_deduce_bounds(struct bpf_reg_state *reg) { __reg32_deduce_bounds(reg); __reg64_deduce_bounds(reg); + __reg_deduce_mixed_bounds(reg); } /* Attempts to improve var_off based on unsigned min/max information */ -- cgit v1.2.3 From d7f00873817129e62f8c70891cb13c8eafe9feef Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 1 Nov 2023 20:37:50 -0700 Subject: bpf: try harder to deduce register bounds from different numeric domains There are cases (caught by subsequent reg_bounds tests in selftests/bpf) where performing one round of __reg_deduce_bounds() doesn't propagate all the information from, say, s32 to u32 bounds and than from newly learned u32 bounds back to u64 and s64. So perform __reg_deduce_bounds() twice to make sure such derivations are propagated fully after reg_bounds_sync(). One such example is test `(s64)[0xffffffff00000001; 0] (u64)< 0xffffffff00000000` from selftest patch from this patch set. It demonstrates an intricate dance of u64 -> s64 -> u64 -> u32 bounds adjustments, which requires two rounds of __reg_deduce_bounds(). Here are corresponding refinement log from selftest, showing evolution of knowledge. REFINING (FALSE R1) (u64)SRC=[0xffffffff00000000; U64_MAX] (u64)DST_OLD=[0; U64_MAX] (u64)DST_NEW=[0xffffffff00000000; U64_MAX] REFINING (FALSE R1) (u64)SRC=[0xffffffff00000000; U64_MAX] (s64)DST_OLD=[0xffffffff00000001; 0] (s64)DST_NEW=[0xffffffff00000001; -1] REFINING (FALSE R1) (s64)SRC=[0xffffffff00000001; -1] (u64)DST_OLD=[0xffffffff00000000; U64_MAX] (u64)DST_NEW=[0xffffffff00000001; U64_MAX] REFINING (FALSE R1) (u64)SRC=[0xffffffff00000001; U64_MAX] (u32)DST_OLD=[0; U32_MAX] (u32)DST_NEW=[1; U32_MAX] R1 initially has smin/smax set to [0xffffffff00000001; -1], while umin/umax is unknown. After (u64)< comparison, in FALSE branch we gain knowledge that umin/umax is [0xffffffff00000000; U64_MAX]. That causes smin/smax to learn that zero can't happen and upper bound is -1. Then smin/smax is adjusted from umin/umax improving lower bound from 0xffffffff00000000 to 0xffffffff00000001. And then eventually umin32/umax32 bounds are drived from umin/umax and become [1; U32_MAX]. Selftest in the last patch is actually implementing a multi-round fixed-point convergence logic, but so far all the tests are handled by two rounds of reg_bounds_sync() on the verifier state, so we keep it simple for now. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231102033759.2541186-9-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 969f1ecfe310..61f17b63ba00 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2605,6 +2605,7 @@ static void reg_bounds_sync(struct bpf_reg_state *reg) __update_reg_bounds(reg); /* We might have learned something about the sign bit. */ __reg_deduce_bounds(reg); + __reg_deduce_bounds(reg); /* We might have learned some bits from the bounds. */ __reg_bound_offset(reg); /* Intersecting with the old var_off might have improved our bounds -- cgit v1.2.3 From 9e314f5d8682e1fe6ac214fb34580a238b6fd3c4 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 1 Nov 2023 20:37:51 -0700 Subject: bpf: drop knowledge-losing __reg_combine_{32,64}_into_{64,32} logic When performing 32-bit conditional operation operating on lower 32 bits of a full 64-bit register, register full value isn't changed. We just potentially gain new knowledge about that register's lower 32 bits. Unfortunately, __reg_combine_{32,64}_into_{64,32} logic that reg_set_min_max() performs as a last step, can lose information in some cases due to __mark_reg64_unbounded() and __reg_assign_32_into_64(). That's bad and completely unnecessary. Especially __reg_assign_32_into_64() looks completely out of place here, because we are not performing zero-extending subregister assignment during conditional jump. So this patch replaced __reg_combine_* with just a normal reg_bounds_sync() which will do a proper job of deriving u64/s64 bounds from u32/s32, and vice versa (among all other combinations). __reg_combine_64_into_32() is also used in one more place, coerce_reg_to_size(), while handling 1- and 2-byte register loads. Looking into this, it seems like besides marking subregister as unbounded before performing reg_bounds_sync(), we were also performing deduction of smin32/smax32 and umin32/umax32 bounds from respective smin/smax and umin/umax bounds. It's now redundant as reg_bounds_sync() performs all the same logic more generically (e.g., without unnecessary assumption that upper 32 bits of full register should be zero). Long story short, we remove __reg_combine_64_into_32() completely, and coerce_reg_to_size() now only does resetting subreg to unbounded and then performing reg_bounds_sync() to recover as much information as possible from 64-bit umin/umax and smin/smax bounds, set explicitly in coerce_reg_to_size() earlier. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Acked-by: Shung-Hsi Yu Link: https://lore.kernel.org/r/20231102033759.2541186-10-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 60 +++++++-------------------------------------------- 1 file changed, 8 insertions(+), 52 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 61f17b63ba00..b4d6b5a032ce 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2639,51 +2639,6 @@ static void __reg_assign_32_into_64(struct bpf_reg_state *reg) } } -static void __reg_combine_32_into_64(struct bpf_reg_state *reg) -{ - /* special case when 64-bit register has upper 32-bit register - * zeroed. Typically happens after zext or <<32, >>32 sequence - * allowing us to use 32-bit bounds directly, - */ - if (tnum_equals_const(tnum_clear_subreg(reg->var_off), 0)) { - __reg_assign_32_into_64(reg); - } else { - /* Otherwise the best we can do is push lower 32bit known and - * unknown bits into register (var_off set from jmp logic) - * then learn as much as possible from the 64-bit tnum - * known and unknown bits. The previous smin/smax bounds are - * invalid here because of jmp32 compare so mark them unknown - * so they do not impact tnum bounds calculation. - */ - __mark_reg64_unbounded(reg); - } - reg_bounds_sync(reg); -} - -static bool __reg64_bound_s32(s64 a) -{ - return a >= S32_MIN && a <= S32_MAX; -} - -static bool __reg64_bound_u32(u64 a) -{ - return a >= U32_MIN && a <= U32_MAX; -} - -static void __reg_combine_64_into_32(struct bpf_reg_state *reg) -{ - __mark_reg32_unbounded(reg); - if (__reg64_bound_s32(reg->smin_value) && __reg64_bound_s32(reg->smax_value)) { - reg->s32_min_value = (s32)reg->smin_value; - reg->s32_max_value = (s32)reg->smax_value; - } - if (__reg64_bound_u32(reg->umin_value) && __reg64_bound_u32(reg->umax_value)) { - reg->u32_min_value = (u32)reg->umin_value; - reg->u32_max_value = (u32)reg->umax_value; - } - reg_bounds_sync(reg); -} - /* Mark a register as having a completely unknown (scalar) value. */ static void __mark_reg_unknown(const struct bpf_verifier_env *env, struct bpf_reg_state *reg) @@ -6387,9 +6342,10 @@ static void coerce_reg_to_size(struct bpf_reg_state *reg, int size) * values are also truncated so we push 64-bit bounds into * 32-bit bounds. Above were truncated < 32-bits already. */ - if (size >= 4) - return; - __reg_combine_64_into_32(reg); + if (size < 4) { + __mark_reg32_unbounded(reg); + reg_bounds_sync(reg); + } } static void set_sext64_default_val(struct bpf_reg_state *reg, int size) @@ -14642,13 +14598,13 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg, tnum_subreg(false_32off)); true_reg->var_off = tnum_or(tnum_clear_subreg(true_64off), tnum_subreg(true_32off)); - __reg_combine_32_into_64(false_reg); - __reg_combine_32_into_64(true_reg); + reg_bounds_sync(false_reg); + reg_bounds_sync(true_reg); } else { false_reg->var_off = false_64off; true_reg->var_off = true_64off; - __reg_combine_64_into_32(false_reg); - __reg_combine_64_into_32(true_reg); + reg_bounds_sync(false_reg); + reg_bounds_sync(true_reg); } } -- cgit v1.2.3 From c2a3ab094683ddc154879a1364fc7cb0228f96a6 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 1 Nov 2023 20:37:53 -0700 Subject: bpf: rename is_branch_taken reg arguments to prepare for the second one Just taking mundane refactoring bits out into a separate patch. No functional changes. Signed-off-by: Andrii Nakryiko Acked-by: Shung-Hsi Yu Link: https://lore.kernel.org/r/20231102033759.2541186-12-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 108 +++++++++++++++++++++++++------------------------- 1 file changed, 54 insertions(+), 54 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index b4d6b5a032ce..770d5bd54ff3 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14188,26 +14188,26 @@ static void find_good_pkt_pointers(struct bpf_verifier_state *vstate, })); } -static int is_branch32_taken(struct bpf_reg_state *reg, u32 val, u8 opcode) +static int is_branch32_taken(struct bpf_reg_state *reg1, u32 val, u8 opcode) { - struct tnum subreg = tnum_subreg(reg->var_off); + struct tnum subreg = tnum_subreg(reg1->var_off); s32 sval = (s32)val; switch (opcode) { case BPF_JEQ: if (tnum_is_const(subreg)) return !!tnum_equals_const(subreg, val); - else if (val < reg->u32_min_value || val > reg->u32_max_value) + else if (val < reg1->u32_min_value || val > reg1->u32_max_value) return 0; - else if (sval < reg->s32_min_value || sval > reg->s32_max_value) + else if (sval < reg1->s32_min_value || sval > reg1->s32_max_value) return 0; break; case BPF_JNE: if (tnum_is_const(subreg)) return !tnum_equals_const(subreg, val); - else if (val < reg->u32_min_value || val > reg->u32_max_value) + else if (val < reg1->u32_min_value || val > reg1->u32_max_value) return 1; - else if (sval < reg->s32_min_value || sval > reg->s32_max_value) + else if (sval < reg1->s32_min_value || sval > reg1->s32_max_value) return 1; break; case BPF_JSET: @@ -14217,51 +14217,51 @@ static int is_branch32_taken(struct bpf_reg_state *reg, u32 val, u8 opcode) return 0; break; case BPF_JGT: - if (reg->u32_min_value > val) + if (reg1->u32_min_value > val) return 1; - else if (reg->u32_max_value <= val) + else if (reg1->u32_max_value <= val) return 0; break; case BPF_JSGT: - if (reg->s32_min_value > sval) + if (reg1->s32_min_value > sval) return 1; - else if (reg->s32_max_value <= sval) + else if (reg1->s32_max_value <= sval) return 0; break; case BPF_JLT: - if (reg->u32_max_value < val) + if (reg1->u32_max_value < val) return 1; - else if (reg->u32_min_value >= val) + else if (reg1->u32_min_value >= val) return 0; break; case BPF_JSLT: - if (reg->s32_max_value < sval) + if (reg1->s32_max_value < sval) return 1; - else if (reg->s32_min_value >= sval) + else if (reg1->s32_min_value >= sval) return 0; break; case BPF_JGE: - if (reg->u32_min_value >= val) + if (reg1->u32_min_value >= val) return 1; - else if (reg->u32_max_value < val) + else if (reg1->u32_max_value < val) return 0; break; case BPF_JSGE: - if (reg->s32_min_value >= sval) + if (reg1->s32_min_value >= sval) return 1; - else if (reg->s32_max_value < sval) + else if (reg1->s32_max_value < sval) return 0; break; case BPF_JLE: - if (reg->u32_max_value <= val) + if (reg1->u32_max_value <= val) return 1; - else if (reg->u32_min_value > val) + else if (reg1->u32_min_value > val) return 0; break; case BPF_JSLE: - if (reg->s32_max_value <= sval) + if (reg1->s32_max_value <= sval) return 1; - else if (reg->s32_min_value > sval) + else if (reg1->s32_min_value > sval) return 0; break; } @@ -14270,79 +14270,79 @@ static int is_branch32_taken(struct bpf_reg_state *reg, u32 val, u8 opcode) } -static int is_branch64_taken(struct bpf_reg_state *reg, u64 val, u8 opcode) +static int is_branch64_taken(struct bpf_reg_state *reg1, u64 val, u8 opcode) { s64 sval = (s64)val; switch (opcode) { case BPF_JEQ: - if (tnum_is_const(reg->var_off)) - return !!tnum_equals_const(reg->var_off, val); - else if (val < reg->umin_value || val > reg->umax_value) + if (tnum_is_const(reg1->var_off)) + return !!tnum_equals_const(reg1->var_off, val); + else if (val < reg1->umin_value || val > reg1->umax_value) return 0; - else if (sval < reg->smin_value || sval > reg->smax_value) + else if (sval < reg1->smin_value || sval > reg1->smax_value) return 0; break; case BPF_JNE: - if (tnum_is_const(reg->var_off)) - return !tnum_equals_const(reg->var_off, val); - else if (val < reg->umin_value || val > reg->umax_value) + if (tnum_is_const(reg1->var_off)) + return !tnum_equals_const(reg1->var_off, val); + else if (val < reg1->umin_value || val > reg1->umax_value) return 1; - else if (sval < reg->smin_value || sval > reg->smax_value) + else if (sval < reg1->smin_value || sval > reg1->smax_value) return 1; break; case BPF_JSET: - if ((~reg->var_off.mask & reg->var_off.value) & val) + if ((~reg1->var_off.mask & reg1->var_off.value) & val) return 1; - if (!((reg->var_off.mask | reg->var_off.value) & val)) + if (!((reg1->var_off.mask | reg1->var_off.value) & val)) return 0; break; case BPF_JGT: - if (reg->umin_value > val) + if (reg1->umin_value > val) return 1; - else if (reg->umax_value <= val) + else if (reg1->umax_value <= val) return 0; break; case BPF_JSGT: - if (reg->smin_value > sval) + if (reg1->smin_value > sval) return 1; - else if (reg->smax_value <= sval) + else if (reg1->smax_value <= sval) return 0; break; case BPF_JLT: - if (reg->umax_value < val) + if (reg1->umax_value < val) return 1; - else if (reg->umin_value >= val) + else if (reg1->umin_value >= val) return 0; break; case BPF_JSLT: - if (reg->smax_value < sval) + if (reg1->smax_value < sval) return 1; - else if (reg->smin_value >= sval) + else if (reg1->smin_value >= sval) return 0; break; case BPF_JGE: - if (reg->umin_value >= val) + if (reg1->umin_value >= val) return 1; - else if (reg->umax_value < val) + else if (reg1->umax_value < val) return 0; break; case BPF_JSGE: - if (reg->smin_value >= sval) + if (reg1->smin_value >= sval) return 1; - else if (reg->smax_value < sval) + else if (reg1->smax_value < sval) return 0; break; case BPF_JLE: - if (reg->umax_value <= val) + if (reg1->umax_value <= val) return 1; - else if (reg->umin_value > val) + else if (reg1->umin_value > val) return 0; break; case BPF_JSLE: - if (reg->smax_value <= sval) + if (reg1->smax_value <= sval) return 1; - else if (reg->smin_value > sval) + else if (reg1->smin_value > sval) return 0; break; } @@ -14357,11 +14357,11 @@ static int is_branch64_taken(struct bpf_reg_state *reg, u64 val, u8 opcode) * -1 - unknown. Example: "if (reg < 5)" is unknown when register value * range [0,10] */ -static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode, +static int is_branch_taken(struct bpf_reg_state *reg1, u64 val, u8 opcode, bool is_jmp32) { - if (__is_pointer_value(false, reg)) { - if (!reg_not_null(reg)) + if (__is_pointer_value(false, reg1)) { + if (!reg_not_null(reg1)) return -1; /* If pointer is valid tests against zero will fail so we can @@ -14381,8 +14381,8 @@ static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode, } if (is_jmp32) - return is_branch32_taken(reg, val, opcode); - return is_branch64_taken(reg, val, opcode); + return is_branch32_taken(reg1, val, opcode); + return is_branch64_taken(reg1, val, opcode); } static int flip_opcode(u32 opcode) -- cgit v1.2.3 From c31534267c180f7ed00288d239a501b554885300 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 1 Nov 2023 20:37:54 -0700 Subject: bpf: generalize is_branch_taken() to work with two registers While still assuming that second register is a constant, generalize is_branch_taken-related code to accept two registers instead of register plus explicit constant value. This also, as a side effect, allows to simplify check_cond_jmp_op() by unifying BPF_K case with BPF_X case, for which we use a fake register to represent BPF_K's imm constant as a register. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Acked-by: Shung-Hsi Yu Link: https://lore.kernel.org/r/20231102033759.2541186-13-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 57 +++++++++++++++++++++++++++++---------------------- 1 file changed, 32 insertions(+), 25 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 770d5bd54ff3..79d01445093b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14188,9 +14188,13 @@ static void find_good_pkt_pointers(struct bpf_verifier_state *vstate, })); } -static int is_branch32_taken(struct bpf_reg_state *reg1, u32 val, u8 opcode) +/* + * , currently assuming reg2 is a constant + */ +static int is_branch32_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, u8 opcode) { struct tnum subreg = tnum_subreg(reg1->var_off); + u32 val = (u32)tnum_subreg(reg2->var_off).value; s32 sval = (s32)val; switch (opcode) { @@ -14270,8 +14274,12 @@ static int is_branch32_taken(struct bpf_reg_state *reg1, u32 val, u8 opcode) } -static int is_branch64_taken(struct bpf_reg_state *reg1, u64 val, u8 opcode) +/* + * , currently assuming reg2 is a constant + */ +static int is_branch64_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, u8 opcode) { + u64 val = reg2->var_off.value; s64 sval = (s64)val; switch (opcode) { @@ -14350,16 +14358,23 @@ static int is_branch64_taken(struct bpf_reg_state *reg1, u64 val, u8 opcode) return -1; } -/* compute branch direction of the expression "if (reg opcode val) goto target;" +/* compute branch direction of the expression "if ( opcode ) goto target;" * and return: * 1 - branch will be taken and "goto target" will be executed * 0 - branch will not be taken and fall-through to next insn - * -1 - unknown. Example: "if (reg < 5)" is unknown when register value + * -1 - unknown. Example: "if (reg1 < 5)" is unknown when register value * range [0,10] */ -static int is_branch_taken(struct bpf_reg_state *reg1, u64 val, u8 opcode, - bool is_jmp32) +static int is_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, + u8 opcode, bool is_jmp32) { + struct tnum reg2_tnum = is_jmp32 ? tnum_subreg(reg2->var_off) : reg2->var_off; + u64 val; + + if (!tnum_is_const(reg2_tnum)) + return -1; + val = reg2_tnum.value; + if (__is_pointer_value(false, reg1)) { if (!reg_not_null(reg1)) return -1; @@ -14381,8 +14396,8 @@ static int is_branch_taken(struct bpf_reg_state *reg1, u64 val, u8 opcode, } if (is_jmp32) - return is_branch32_taken(reg1, val, opcode); - return is_branch64_taken(reg1, val, opcode); + return is_branch32_taken(reg1, reg2, opcode); + return is_branch64_taken(reg1, reg2, opcode); } static int flip_opcode(u32 opcode) @@ -14853,6 +14868,7 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env, struct bpf_reg_state *regs = this_branch->frame[this_branch->curframe]->regs; struct bpf_reg_state *dst_reg, *other_branch_regs, *src_reg = NULL; struct bpf_reg_state *eq_branch_regs; + struct bpf_reg_state fake_reg = {}; u8 opcode = BPF_OP(insn->code); bool is_jmp32; int pred = -1; @@ -14893,36 +14909,27 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env, verbose(env, "BPF_JMP/JMP32 uses reserved fields\n"); return -EINVAL; } + src_reg = &fake_reg; + src_reg->type = SCALAR_VALUE; + __mark_reg_known(src_reg, insn->imm); } is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32; if (BPF_SRC(insn->code) == BPF_K) { - pred = is_branch_taken(dst_reg, insn->imm, opcode, is_jmp32); + pred = is_branch_taken(dst_reg, src_reg, opcode, is_jmp32); } else if (src_reg->type == SCALAR_VALUE && is_jmp32 && tnum_is_const(tnum_subreg(src_reg->var_off))) { - pred = is_branch_taken(dst_reg, - tnum_subreg(src_reg->var_off).value, - opcode, - is_jmp32); + pred = is_branch_taken(dst_reg, src_reg, opcode, is_jmp32); } else if (src_reg->type == SCALAR_VALUE && !is_jmp32 && tnum_is_const(src_reg->var_off)) { - pred = is_branch_taken(dst_reg, - src_reg->var_off.value, - opcode, - is_jmp32); + pred = is_branch_taken(dst_reg, src_reg, opcode, is_jmp32); } else if (dst_reg->type == SCALAR_VALUE && is_jmp32 && tnum_is_const(tnum_subreg(dst_reg->var_off))) { - pred = is_branch_taken(src_reg, - tnum_subreg(dst_reg->var_off).value, - flip_opcode(opcode), - is_jmp32); + pred = is_branch_taken(src_reg, dst_reg, flip_opcode(opcode), is_jmp32); } else if (dst_reg->type == SCALAR_VALUE && !is_jmp32 && tnum_is_const(dst_reg->var_off)) { - pred = is_branch_taken(src_reg, - dst_reg->var_off.value, - flip_opcode(opcode), - is_jmp32); + pred = is_branch_taken(src_reg, dst_reg, flip_opcode(opcode), is_jmp32); } else if (reg_is_pkt_pointer_any(dst_reg) && reg_is_pkt_pointer_any(src_reg) && !is_jmp32) { -- cgit v1.2.3 From c697289efe4ef38bc5c62f119cb74433f784b826 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 1 Nov 2023 20:37:55 -0700 Subject: bpf: move is_branch_taken() down Move is_branch_taken() slightly down. In subsequent patched we'll need both flip_opcode() and is_pkt_ptr_branch_taken() for is_branch_taken(), but instead of sprinkling forward declarations around, it makes more sense to move is_branch_taken() lower below is_pkt_ptr_branch_taken(), and also keep it closer to very tightly related reg_set_min_max(), as they are two critical parts of the same SCALAR range tracking logic. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231102033759.2541186-14-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 84 +++++++++++++++++++++++++-------------------------- 1 file changed, 42 insertions(+), 42 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 79d01445093b..414a7c58b4a4 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14358,48 +14358,6 @@ static int is_branch64_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *r return -1; } -/* compute branch direction of the expression "if ( opcode ) goto target;" - * and return: - * 1 - branch will be taken and "goto target" will be executed - * 0 - branch will not be taken and fall-through to next insn - * -1 - unknown. Example: "if (reg1 < 5)" is unknown when register value - * range [0,10] - */ -static int is_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, - u8 opcode, bool is_jmp32) -{ - struct tnum reg2_tnum = is_jmp32 ? tnum_subreg(reg2->var_off) : reg2->var_off; - u64 val; - - if (!tnum_is_const(reg2_tnum)) - return -1; - val = reg2_tnum.value; - - if (__is_pointer_value(false, reg1)) { - if (!reg_not_null(reg1)) - return -1; - - /* If pointer is valid tests against zero will fail so we can - * use this to direct branch taken. - */ - if (val != 0) - return -1; - - switch (opcode) { - case BPF_JEQ: - return 0; - case BPF_JNE: - return 1; - default: - return -1; - } - } - - if (is_jmp32) - return is_branch32_taken(reg1, reg2, opcode); - return is_branch64_taken(reg1, reg2, opcode); -} - static int flip_opcode(u32 opcode) { /* How can we transform "a b" into "b a"? */ @@ -14461,6 +14419,48 @@ static int is_pkt_ptr_branch_taken(struct bpf_reg_state *dst_reg, return -1; } +/* compute branch direction of the expression "if ( opcode ) goto target;" + * and return: + * 1 - branch will be taken and "goto target" will be executed + * 0 - branch will not be taken and fall-through to next insn + * -1 - unknown. Example: "if (reg1 < 5)" is unknown when register value + * range [0,10] + */ +static int is_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, + u8 opcode, bool is_jmp32) +{ + struct tnum reg2_tnum = is_jmp32 ? tnum_subreg(reg2->var_off) : reg2->var_off; + u64 val; + + if (!tnum_is_const(reg2_tnum)) + return -1; + val = reg2_tnum.value; + + if (__is_pointer_value(false, reg1)) { + if (!reg_not_null(reg1)) + return -1; + + /* If pointer is valid tests against zero will fail so we can + * use this to direct branch taken. + */ + if (val != 0) + return -1; + + switch (opcode) { + case BPF_JEQ: + return 0; + case BPF_JNE: + return 1; + default: + return -1; + } + } + + if (is_jmp32) + return is_branch32_taken(reg1, reg2, opcode); + return is_branch64_taken(reg1, reg2, opcode); +} + /* Adjusts the register min/max values in the case that the dst_reg is the * variable register that we are working on, and src_reg is a constant or we're * simply doing a BPF_K check. -- cgit v1.2.3 From b74c2a842bba941945279027083fcee1e9aaa73f Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 1 Nov 2023 20:37:56 -0700 Subject: bpf: generalize is_branch_taken to handle all conditional jumps in one place Make is_branch_taken() a single entry point for branch pruning decision making, handling both pointer vs pointer, pointer vs scalar, and scalar vs scalar cases in one place. This also nicely cleans up check_cond_jmp_op(). Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231102033759.2541186-15-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 49 +++++++++++++++++++++++++------------------------ 1 file changed, 25 insertions(+), 24 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 414a7c58b4a4..17bbff33e0e8 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14188,6 +14188,19 @@ static void find_good_pkt_pointers(struct bpf_verifier_state *vstate, })); } +/* check if register is a constant scalar value */ +static bool is_reg_const(struct bpf_reg_state *reg, bool subreg32) +{ + return reg->type == SCALAR_VALUE && + tnum_is_const(subreg32 ? tnum_subreg(reg->var_off) : reg->var_off); +} + +/* assuming is_reg_const() is true, return constant value of a register */ +static u64 reg_const_value(struct bpf_reg_state *reg, bool subreg32) +{ + return subreg32 ? tnum_subreg(reg->var_off).value : reg->var_off.value; +} + /* * , currently assuming reg2 is a constant */ @@ -14429,12 +14442,20 @@ static int is_pkt_ptr_branch_taken(struct bpf_reg_state *dst_reg, static int is_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, u8 opcode, bool is_jmp32) { - struct tnum reg2_tnum = is_jmp32 ? tnum_subreg(reg2->var_off) : reg2->var_off; u64 val; - if (!tnum_is_const(reg2_tnum)) + if (reg_is_pkt_pointer_any(reg1) && reg_is_pkt_pointer_any(reg2) && !is_jmp32) + return is_pkt_ptr_branch_taken(reg1, reg2, opcode); + + /* try to make sure reg2 is a constant SCALAR_VALUE */ + if (!is_reg_const(reg2, is_jmp32)) { + opcode = flip_opcode(opcode); + swap(reg1, reg2); + } + /* for now we expect reg2 to be a constant to make any useful decisions */ + if (!is_reg_const(reg2, is_jmp32)) return -1; - val = reg2_tnum.value; + val = reg_const_value(reg2, is_jmp32); if (__is_pointer_value(false, reg1)) { if (!reg_not_null(reg1)) @@ -14915,27 +14936,7 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env, } is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32; - - if (BPF_SRC(insn->code) == BPF_K) { - pred = is_branch_taken(dst_reg, src_reg, opcode, is_jmp32); - } else if (src_reg->type == SCALAR_VALUE && - is_jmp32 && tnum_is_const(tnum_subreg(src_reg->var_off))) { - pred = is_branch_taken(dst_reg, src_reg, opcode, is_jmp32); - } else if (src_reg->type == SCALAR_VALUE && - !is_jmp32 && tnum_is_const(src_reg->var_off)) { - pred = is_branch_taken(dst_reg, src_reg, opcode, is_jmp32); - } else if (dst_reg->type == SCALAR_VALUE && - is_jmp32 && tnum_is_const(tnum_subreg(dst_reg->var_off))) { - pred = is_branch_taken(src_reg, dst_reg, flip_opcode(opcode), is_jmp32); - } else if (dst_reg->type == SCALAR_VALUE && - !is_jmp32 && tnum_is_const(dst_reg->var_off)) { - pred = is_branch_taken(src_reg, dst_reg, flip_opcode(opcode), is_jmp32); - } else if (reg_is_pkt_pointer_any(dst_reg) && - reg_is_pkt_pointer_any(src_reg) && - !is_jmp32) { - pred = is_pkt_ptr_branch_taken(dst_reg, src_reg, opcode); - } - + pred = is_branch_taken(dst_reg, src_reg, opcode, is_jmp32); if (pred >= 0) { /* If we get here with a dst_reg pointer type it is because * above is_branch_taken() special cased the 0 comparison. -- cgit v1.2.3 From 4d345887d2e5a1915600cb5d37b16c4088c6ee1c Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 1 Nov 2023 20:37:57 -0700 Subject: bpf: unify 32-bit and 64-bit is_branch_taken logic Combine 32-bit and 64-bit is_branch_taken logic for SCALAR_VALUE registers. It makes it easier to see parallels between two domains (32-bit and 64-bit), and makes subsequent refactoring more straightforward. No functional changes. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231102033759.2541186-16-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 200 +++++++++++++++----------------------------------- 1 file changed, 59 insertions(+), 141 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 17bbff33e0e8..c77cca5c4461 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14204,166 +14204,86 @@ static u64 reg_const_value(struct bpf_reg_state *reg, bool subreg32) /* * , currently assuming reg2 is a constant */ -static int is_branch32_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, u8 opcode) +static int is_scalar_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, + u8 opcode, bool is_jmp32) { - struct tnum subreg = tnum_subreg(reg1->var_off); - u32 val = (u32)tnum_subreg(reg2->var_off).value; - s32 sval = (s32)val; + struct tnum t1 = is_jmp32 ? tnum_subreg(reg1->var_off) : reg1->var_off; + u64 umin1 = is_jmp32 ? (u64)reg1->u32_min_value : reg1->umin_value; + u64 umax1 = is_jmp32 ? (u64)reg1->u32_max_value : reg1->umax_value; + s64 smin1 = is_jmp32 ? (s64)reg1->s32_min_value : reg1->smin_value; + s64 smax1 = is_jmp32 ? (s64)reg1->s32_max_value : reg1->smax_value; + u64 uval = is_jmp32 ? (u32)tnum_subreg(reg2->var_off).value : reg2->var_off.value; + s64 sval = is_jmp32 ? (s32)uval : (s64)uval; switch (opcode) { case BPF_JEQ: - if (tnum_is_const(subreg)) - return !!tnum_equals_const(subreg, val); - else if (val < reg1->u32_min_value || val > reg1->u32_max_value) + if (tnum_is_const(t1)) + return !!tnum_equals_const(t1, uval); + else if (uval < umin1 || uval > umax1) return 0; - else if (sval < reg1->s32_min_value || sval > reg1->s32_max_value) + else if (sval < smin1 || sval > smax1) return 0; break; case BPF_JNE: - if (tnum_is_const(subreg)) - return !tnum_equals_const(subreg, val); - else if (val < reg1->u32_min_value || val > reg1->u32_max_value) + if (tnum_is_const(t1)) + return !tnum_equals_const(t1, uval); + else if (uval < umin1 || uval > umax1) return 1; - else if (sval < reg1->s32_min_value || sval > reg1->s32_max_value) + else if (sval < smin1 || sval > smax1) return 1; break; case BPF_JSET: - if ((~subreg.mask & subreg.value) & val) + if ((~t1.mask & t1.value) & uval) return 1; - if (!((subreg.mask | subreg.value) & val)) + if (!((t1.mask | t1.value) & uval)) return 0; break; case BPF_JGT: - if (reg1->u32_min_value > val) + if (umin1 > uval ) return 1; - else if (reg1->u32_max_value <= val) + else if (umax1 <= uval) return 0; break; case BPF_JSGT: - if (reg1->s32_min_value > sval) + if (smin1 > sval) return 1; - else if (reg1->s32_max_value <= sval) + else if (smax1 <= sval) return 0; break; case BPF_JLT: - if (reg1->u32_max_value < val) + if (umax1 < uval) return 1; - else if (reg1->u32_min_value >= val) + else if (umin1 >= uval) return 0; break; case BPF_JSLT: - if (reg1->s32_max_value < sval) + if (smax1 < sval) return 1; - else if (reg1->s32_min_value >= sval) + else if (smin1 >= sval) return 0; break; case BPF_JGE: - if (reg1->u32_min_value >= val) + if (umin1 >= uval) return 1; - else if (reg1->u32_max_value < val) + else if (umax1 < uval) return 0; break; case BPF_JSGE: - if (reg1->s32_min_value >= sval) + if (smin1 >= sval) return 1; - else if (reg1->s32_max_value < sval) + else if (smax1 < sval) return 0; break; case BPF_JLE: - if (reg1->u32_max_value <= val) + if (umax1 <= uval) return 1; - else if (reg1->u32_min_value > val) + else if (umin1 > uval) return 0; break; case BPF_JSLE: - if (reg1->s32_max_value <= sval) + if (smax1 <= sval) return 1; - else if (reg1->s32_min_value > sval) - return 0; - break; - } - - return -1; -} - - -/* - * , currently assuming reg2 is a constant - */ -static int is_branch64_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, u8 opcode) -{ - u64 val = reg2->var_off.value; - s64 sval = (s64)val; - - switch (opcode) { - case BPF_JEQ: - if (tnum_is_const(reg1->var_off)) - return !!tnum_equals_const(reg1->var_off, val); - else if (val < reg1->umin_value || val > reg1->umax_value) - return 0; - else if (sval < reg1->smin_value || sval > reg1->smax_value) - return 0; - break; - case BPF_JNE: - if (tnum_is_const(reg1->var_off)) - return !tnum_equals_const(reg1->var_off, val); - else if (val < reg1->umin_value || val > reg1->umax_value) - return 1; - else if (sval < reg1->smin_value || sval > reg1->smax_value) - return 1; - break; - case BPF_JSET: - if ((~reg1->var_off.mask & reg1->var_off.value) & val) - return 1; - if (!((reg1->var_off.mask | reg1->var_off.value) & val)) - return 0; - break; - case BPF_JGT: - if (reg1->umin_value > val) - return 1; - else if (reg1->umax_value <= val) - return 0; - break; - case BPF_JSGT: - if (reg1->smin_value > sval) - return 1; - else if (reg1->smax_value <= sval) - return 0; - break; - case BPF_JLT: - if (reg1->umax_value < val) - return 1; - else if (reg1->umin_value >= val) - return 0; - break; - case BPF_JSLT: - if (reg1->smax_value < sval) - return 1; - else if (reg1->smin_value >= sval) - return 0; - break; - case BPF_JGE: - if (reg1->umin_value >= val) - return 1; - else if (reg1->umax_value < val) - return 0; - break; - case BPF_JSGE: - if (reg1->smin_value >= sval) - return 1; - else if (reg1->smax_value < sval) - return 0; - break; - case BPF_JLE: - if (reg1->umax_value <= val) - return 1; - else if (reg1->umin_value > val) - return 0; - break; - case BPF_JSLE: - if (reg1->smax_value <= sval) - return 1; - else if (reg1->smin_value > sval) + else if (smin1 > sval) return 0; break; } @@ -14477,9 +14397,7 @@ static int is_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg } } - if (is_jmp32) - return is_branch32_taken(reg1, reg2, opcode); - return is_branch64_taken(reg1, reg2, opcode); + return is_scalar_branch_taken(reg1, reg2, opcode, is_jmp32); } /* Adjusts the register min/max values in the case that the dst_reg is the @@ -14489,15 +14407,15 @@ static int is_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg */ static void reg_set_min_max(struct bpf_reg_state *true_reg, struct bpf_reg_state *false_reg, - u64 val, u32 val32, + u64 uval, u32 uval32, u8 opcode, bool is_jmp32) { struct tnum false_32off = tnum_subreg(false_reg->var_off); struct tnum false_64off = false_reg->var_off; struct tnum true_32off = tnum_subreg(true_reg->var_off); struct tnum true_64off = true_reg->var_off; - s64 sval = (s64)val; - s32 sval32 = (s32)val32; + s64 sval = (s64)uval; + s32 sval32 = (s32)uval32; /* If the dst_reg is a pointer, we can't learn anything about its * variable offset from the compare (unless src_reg were a pointer into @@ -14520,49 +14438,49 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg, */ case BPF_JEQ: if (is_jmp32) { - __mark_reg32_known(true_reg, val32); + __mark_reg32_known(true_reg, uval32); true_32off = tnum_subreg(true_reg->var_off); } else { - ___mark_reg_known(true_reg, val); + ___mark_reg_known(true_reg, uval); true_64off = true_reg->var_off; } break; case BPF_JNE: if (is_jmp32) { - __mark_reg32_known(false_reg, val32); + __mark_reg32_known(false_reg, uval32); false_32off = tnum_subreg(false_reg->var_off); } else { - ___mark_reg_known(false_reg, val); + ___mark_reg_known(false_reg, uval); false_64off = false_reg->var_off; } break; case BPF_JSET: if (is_jmp32) { - false_32off = tnum_and(false_32off, tnum_const(~val32)); - if (is_power_of_2(val32)) + false_32off = tnum_and(false_32off, tnum_const(~uval32)); + if (is_power_of_2(uval32)) true_32off = tnum_or(true_32off, - tnum_const(val32)); + tnum_const(uval32)); } else { - false_64off = tnum_and(false_64off, tnum_const(~val)); - if (is_power_of_2(val)) + false_64off = tnum_and(false_64off, tnum_const(~uval)); + if (is_power_of_2(uval)) true_64off = tnum_or(true_64off, - tnum_const(val)); + tnum_const(uval)); } break; case BPF_JGE: case BPF_JGT: { if (is_jmp32) { - u32 false_umax = opcode == BPF_JGT ? val32 : val32 - 1; - u32 true_umin = opcode == BPF_JGT ? val32 + 1 : val32; + u32 false_umax = opcode == BPF_JGT ? uval32 : uval32 - 1; + u32 true_umin = opcode == BPF_JGT ? uval32 + 1 : uval32; false_reg->u32_max_value = min(false_reg->u32_max_value, false_umax); true_reg->u32_min_value = max(true_reg->u32_min_value, true_umin); } else { - u64 false_umax = opcode == BPF_JGT ? val : val - 1; - u64 true_umin = opcode == BPF_JGT ? val + 1 : val; + u64 false_umax = opcode == BPF_JGT ? uval : uval - 1; + u64 true_umin = opcode == BPF_JGT ? uval + 1 : uval; false_reg->umax_value = min(false_reg->umax_value, false_umax); true_reg->umin_value = max(true_reg->umin_value, true_umin); @@ -14591,16 +14509,16 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg, case BPF_JLT: { if (is_jmp32) { - u32 false_umin = opcode == BPF_JLT ? val32 : val32 + 1; - u32 true_umax = opcode == BPF_JLT ? val32 - 1 : val32; + u32 false_umin = opcode == BPF_JLT ? uval32 : uval32 + 1; + u32 true_umax = opcode == BPF_JLT ? uval32 - 1 : uval32; false_reg->u32_min_value = max(false_reg->u32_min_value, false_umin); true_reg->u32_max_value = min(true_reg->u32_max_value, true_umax); } else { - u64 false_umin = opcode == BPF_JLT ? val : val + 1; - u64 true_umax = opcode == BPF_JLT ? val - 1 : val; + u64 false_umin = opcode == BPF_JLT ? uval : uval + 1; + u64 true_umax = opcode == BPF_JLT ? uval - 1 : uval; false_reg->umin_value = max(false_reg->umin_value, false_umin); true_reg->umax_value = min(true_reg->umax_value, true_umax); @@ -14649,7 +14567,7 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg, */ static void reg_set_min_max_inv(struct bpf_reg_state *true_reg, struct bpf_reg_state *false_reg, - u64 val, u32 val32, + u64 uval, u32 uval32, u8 opcode, bool is_jmp32) { opcode = flip_opcode(opcode); @@ -14657,7 +14575,7 @@ static void reg_set_min_max_inv(struct bpf_reg_state *true_reg, * BPF_JA, can't get here. */ if (opcode) - reg_set_min_max(true_reg, false_reg, val, val32, opcode, is_jmp32); + reg_set_min_max(true_reg, false_reg, uval, uval32, opcode, is_jmp32); } /* Regs are known to be equal, so intersect their min/max/var_off */ -- cgit v1.2.3 From 811476e9cc578cb6c776627ac069dc45a8431791 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 1 Nov 2023 20:37:58 -0700 Subject: bpf: prepare reg_set_min_max for second set of registers Similarly to is_branch_taken()-related refactorings, start preparing reg_set_min_max() to handle more generic case of two non-const registers. Start with renaming arguments to accommodate later addition of second register as an input argument. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231102033759.2541186-17-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 80 +++++++++++++++++++++++++-------------------------- 1 file changed, 40 insertions(+), 40 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index c77cca5c4461..40ed261d3489 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14405,25 +14405,25 @@ static int is_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg * simply doing a BPF_K check. * In JEQ/JNE cases we also adjust the var_off values. */ -static void reg_set_min_max(struct bpf_reg_state *true_reg, - struct bpf_reg_state *false_reg, +static void reg_set_min_max(struct bpf_reg_state *true_reg1, + struct bpf_reg_state *false_reg1, u64 uval, u32 uval32, u8 opcode, bool is_jmp32) { - struct tnum false_32off = tnum_subreg(false_reg->var_off); - struct tnum false_64off = false_reg->var_off; - struct tnum true_32off = tnum_subreg(true_reg->var_off); - struct tnum true_64off = true_reg->var_off; + struct tnum false_32off = tnum_subreg(false_reg1->var_off); + struct tnum false_64off = false_reg1->var_off; + struct tnum true_32off = tnum_subreg(true_reg1->var_off); + struct tnum true_64off = true_reg1->var_off; s64 sval = (s64)uval; s32 sval32 = (s32)uval32; /* If the dst_reg is a pointer, we can't learn anything about its * variable offset from the compare (unless src_reg were a pointer into * the same object, but we don't bother with that. - * Since false_reg and true_reg have the same type by construction, we + * Since false_reg1 and true_reg1 have the same type by construction, we * only need to check one of them for pointerness. */ - if (__is_pointer_value(false, false_reg)) + if (__is_pointer_value(false, false_reg1)) return; switch (opcode) { @@ -14438,20 +14438,20 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg, */ case BPF_JEQ: if (is_jmp32) { - __mark_reg32_known(true_reg, uval32); - true_32off = tnum_subreg(true_reg->var_off); + __mark_reg32_known(true_reg1, uval32); + true_32off = tnum_subreg(true_reg1->var_off); } else { - ___mark_reg_known(true_reg, uval); - true_64off = true_reg->var_off; + ___mark_reg_known(true_reg1, uval); + true_64off = true_reg1->var_off; } break; case BPF_JNE: if (is_jmp32) { - __mark_reg32_known(false_reg, uval32); - false_32off = tnum_subreg(false_reg->var_off); + __mark_reg32_known(false_reg1, uval32); + false_32off = tnum_subreg(false_reg1->var_off); } else { - ___mark_reg_known(false_reg, uval); - false_64off = false_reg->var_off; + ___mark_reg_known(false_reg1, uval); + false_64off = false_reg1->var_off; } break; case BPF_JSET: @@ -14474,16 +14474,16 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg, u32 false_umax = opcode == BPF_JGT ? uval32 : uval32 - 1; u32 true_umin = opcode == BPF_JGT ? uval32 + 1 : uval32; - false_reg->u32_max_value = min(false_reg->u32_max_value, + false_reg1->u32_max_value = min(false_reg1->u32_max_value, false_umax); - true_reg->u32_min_value = max(true_reg->u32_min_value, + true_reg1->u32_min_value = max(true_reg1->u32_min_value, true_umin); } else { u64 false_umax = opcode == BPF_JGT ? uval : uval - 1; u64 true_umin = opcode == BPF_JGT ? uval + 1 : uval; - false_reg->umax_value = min(false_reg->umax_value, false_umax); - true_reg->umin_value = max(true_reg->umin_value, true_umin); + false_reg1->umax_value = min(false_reg1->umax_value, false_umax); + true_reg1->umin_value = max(true_reg1->umin_value, true_umin); } break; } @@ -14494,14 +14494,14 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg, s32 false_smax = opcode == BPF_JSGT ? sval32 : sval32 - 1; s32 true_smin = opcode == BPF_JSGT ? sval32 + 1 : sval32; - false_reg->s32_max_value = min(false_reg->s32_max_value, false_smax); - true_reg->s32_min_value = max(true_reg->s32_min_value, true_smin); + false_reg1->s32_max_value = min(false_reg1->s32_max_value, false_smax); + true_reg1->s32_min_value = max(true_reg1->s32_min_value, true_smin); } else { s64 false_smax = opcode == BPF_JSGT ? sval : sval - 1; s64 true_smin = opcode == BPF_JSGT ? sval + 1 : sval; - false_reg->smax_value = min(false_reg->smax_value, false_smax); - true_reg->smin_value = max(true_reg->smin_value, true_smin); + false_reg1->smax_value = min(false_reg1->smax_value, false_smax); + true_reg1->smin_value = max(true_reg1->smin_value, true_smin); } break; } @@ -14512,16 +14512,16 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg, u32 false_umin = opcode == BPF_JLT ? uval32 : uval32 + 1; u32 true_umax = opcode == BPF_JLT ? uval32 - 1 : uval32; - false_reg->u32_min_value = max(false_reg->u32_min_value, + false_reg1->u32_min_value = max(false_reg1->u32_min_value, false_umin); - true_reg->u32_max_value = min(true_reg->u32_max_value, + true_reg1->u32_max_value = min(true_reg1->u32_max_value, true_umax); } else { u64 false_umin = opcode == BPF_JLT ? uval : uval + 1; u64 true_umax = opcode == BPF_JLT ? uval - 1 : uval; - false_reg->umin_value = max(false_reg->umin_value, false_umin); - true_reg->umax_value = min(true_reg->umax_value, true_umax); + false_reg1->umin_value = max(false_reg1->umin_value, false_umin); + true_reg1->umax_value = min(true_reg1->umax_value, true_umax); } break; } @@ -14532,14 +14532,14 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg, s32 false_smin = opcode == BPF_JSLT ? sval32 : sval32 + 1; s32 true_smax = opcode == BPF_JSLT ? sval32 - 1 : sval32; - false_reg->s32_min_value = max(false_reg->s32_min_value, false_smin); - true_reg->s32_max_value = min(true_reg->s32_max_value, true_smax); + false_reg1->s32_min_value = max(false_reg1->s32_min_value, false_smin); + true_reg1->s32_max_value = min(true_reg1->s32_max_value, true_smax); } else { s64 false_smin = opcode == BPF_JSLT ? sval : sval + 1; s64 true_smax = opcode == BPF_JSLT ? sval - 1 : sval; - false_reg->smin_value = max(false_reg->smin_value, false_smin); - true_reg->smax_value = min(true_reg->smax_value, true_smax); + false_reg1->smin_value = max(false_reg1->smin_value, false_smin); + true_reg1->smax_value = min(true_reg1->smax_value, true_smax); } break; } @@ -14548,17 +14548,17 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg, } if (is_jmp32) { - false_reg->var_off = tnum_or(tnum_clear_subreg(false_64off), + false_reg1->var_off = tnum_or(tnum_clear_subreg(false_64off), tnum_subreg(false_32off)); - true_reg->var_off = tnum_or(tnum_clear_subreg(true_64off), + true_reg1->var_off = tnum_or(tnum_clear_subreg(true_64off), tnum_subreg(true_32off)); - reg_bounds_sync(false_reg); - reg_bounds_sync(true_reg); + reg_bounds_sync(false_reg1); + reg_bounds_sync(true_reg1); } else { - false_reg->var_off = false_64off; - true_reg->var_off = true_64off; - reg_bounds_sync(false_reg); - reg_bounds_sync(true_reg); + false_reg1->var_off = false_64off; + true_reg1->var_off = true_64off; + reg_bounds_sync(false_reg1); + reg_bounds_sync(true_reg1); } } -- cgit v1.2.3 From 4621202adc5bc0d1006af37fe8b9aca131387d3c Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 1 Nov 2023 20:37:59 -0700 Subject: bpf: generalize reg_set_min_max() to handle two sets of two registers Change reg_set_min_max() to take FALSE/TRUE sets of two registers each, instead of assuming that we are always comparing to a constant. For now we still assume that right-hand side registers are constants (and make sure that's the case by swapping src/dst regs, if necessary), but subsequent patches will remove this limitation. reg_set_min_max() is now called unconditionally for any register comparison, so that might include pointer vs pointer. This makes it consistent with is_branch_taken() generality. But we currently only support adjustments based on SCALAR vs SCALAR comparisons, so reg_set_min_max() has to guard itself againts pointers. Taking two by two registers allows to further unify and simplify check_cond_jmp_op() logic. We utilize fake register for BPF_K conditional jump case, just like with is_branch_taken() part. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231102033759.2541186-18-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 131 +++++++++++++++++++++----------------------------- 1 file changed, 56 insertions(+), 75 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 40ed261d3489..e801c50d3857 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14400,32 +14400,50 @@ static int is_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg return is_scalar_branch_taken(reg1, reg2, opcode, is_jmp32); } -/* Adjusts the register min/max values in the case that the dst_reg is the - * variable register that we are working on, and src_reg is a constant or we're - * simply doing a BPF_K check. - * In JEQ/JNE cases we also adjust the var_off values. +/* Adjusts the register min/max values in the case that the dst_reg and + * src_reg are both SCALAR_VALUE registers (or we are simply doing a BPF_K + * check, in which case we havea fake SCALAR_VALUE representing insn->imm). + * Technically we can do similar adjustments for pointers to the same object, + * but we don't support that right now. */ static void reg_set_min_max(struct bpf_reg_state *true_reg1, + struct bpf_reg_state *true_reg2, struct bpf_reg_state *false_reg1, - u64 uval, u32 uval32, + struct bpf_reg_state *false_reg2, u8 opcode, bool is_jmp32) { - struct tnum false_32off = tnum_subreg(false_reg1->var_off); - struct tnum false_64off = false_reg1->var_off; - struct tnum true_32off = tnum_subreg(true_reg1->var_off); - struct tnum true_64off = true_reg1->var_off; - s64 sval = (s64)uval; - s32 sval32 = (s32)uval32; - - /* If the dst_reg is a pointer, we can't learn anything about its - * variable offset from the compare (unless src_reg were a pointer into - * the same object, but we don't bother with that. - * Since false_reg1 and true_reg1 have the same type by construction, we - * only need to check one of them for pointerness. + struct tnum false_32off, false_64off; + struct tnum true_32off, true_64off; + u64 uval; + u32 uval32; + s64 sval; + s32 sval32; + + /* If either register is a pointer, we can't learn anything about its + * variable offset from the compare (unless they were a pointer into + * the same object, but we don't bother with that). */ - if (__is_pointer_value(false, false_reg1)) + if (false_reg1->type != SCALAR_VALUE || false_reg2->type != SCALAR_VALUE) + return; + + /* we expect right-hand registers (src ones) to be constants, for now */ + if (!is_reg_const(false_reg2, is_jmp32)) { + opcode = flip_opcode(opcode); + swap(true_reg1, true_reg2); + swap(false_reg1, false_reg2); + } + if (!is_reg_const(false_reg2, is_jmp32)) return; + false_32off = tnum_subreg(false_reg1->var_off); + false_64off = false_reg1->var_off; + true_32off = tnum_subreg(true_reg1->var_off); + true_64off = true_reg1->var_off; + uval = false_reg2->var_off.value; + uval32 = (u32)tnum_subreg(false_reg2->var_off).value; + sval = (s64)uval; + sval32 = (s32)uval32; + switch (opcode) { /* JEQ/JNE comparison doesn't change the register equivalence. * @@ -14562,22 +14580,6 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg1, } } -/* Same as above, but for the case that dst_reg holds a constant and src_reg is - * the variable reg. - */ -static void reg_set_min_max_inv(struct bpf_reg_state *true_reg, - struct bpf_reg_state *false_reg, - u64 uval, u32 uval32, - u8 opcode, bool is_jmp32) -{ - opcode = flip_opcode(opcode); - /* This uses zero as "not present in table"; luckily the zero opcode, - * BPF_JA, can't get here. - */ - if (opcode) - reg_set_min_max(true_reg, false_reg, uval, uval32, opcode, is_jmp32); -} - /* Regs are known to be equal, so intersect their min/max/var_off */ static void __reg_combine_min_max(struct bpf_reg_state *src_reg, struct bpf_reg_state *dst_reg) @@ -14902,53 +14904,32 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env, return -EFAULT; other_branch_regs = other_branch->frame[other_branch->curframe]->regs; - /* detect if we are comparing against a constant value so we can adjust - * our min/max values for our dst register. - * this is only legit if both are scalars (or pointers to the same - * object, I suppose, see the PTR_MAYBE_NULL related if block below), - * because otherwise the different base pointers mean the offsets aren't - * comparable. - */ if (BPF_SRC(insn->code) == BPF_X) { - struct bpf_reg_state *src_reg = ®s[insn->src_reg]; + reg_set_min_max(&other_branch_regs[insn->dst_reg], + &other_branch_regs[insn->src_reg], + dst_reg, src_reg, opcode, is_jmp32); if (dst_reg->type == SCALAR_VALUE && - src_reg->type == SCALAR_VALUE) { - if (tnum_is_const(src_reg->var_off) || - (is_jmp32 && - tnum_is_const(tnum_subreg(src_reg->var_off)))) - reg_set_min_max(&other_branch_regs[insn->dst_reg], - dst_reg, - src_reg->var_off.value, - tnum_subreg(src_reg->var_off).value, - opcode, is_jmp32); - else if (tnum_is_const(dst_reg->var_off) || - (is_jmp32 && - tnum_is_const(tnum_subreg(dst_reg->var_off)))) - reg_set_min_max_inv(&other_branch_regs[insn->src_reg], - src_reg, - dst_reg->var_off.value, - tnum_subreg(dst_reg->var_off).value, - opcode, is_jmp32); - else if (!is_jmp32 && - (opcode == BPF_JEQ || opcode == BPF_JNE)) - /* Comparing for equality, we can combine knowledge */ - reg_combine_min_max(&other_branch_regs[insn->src_reg], - &other_branch_regs[insn->dst_reg], - src_reg, dst_reg, opcode); - if (src_reg->id && - !WARN_ON_ONCE(src_reg->id != other_branch_regs[insn->src_reg].id)) { - find_equal_scalars(this_branch, src_reg); - find_equal_scalars(other_branch, &other_branch_regs[insn->src_reg]); - } - - } - } else if (dst_reg->type == SCALAR_VALUE) { + src_reg->type == SCALAR_VALUE && + !is_jmp32 && (opcode == BPF_JEQ || opcode == BPF_JNE)) { + /* Comparing for equality, we can combine knowledge */ + reg_combine_min_max(&other_branch_regs[insn->src_reg], + &other_branch_regs[insn->dst_reg], + src_reg, dst_reg, opcode); + } + } else /* BPF_SRC(insn->code) == BPF_K */ { reg_set_min_max(&other_branch_regs[insn->dst_reg], - dst_reg, insn->imm, (u32)insn->imm, - opcode, is_jmp32); + src_reg /* fake one */, + dst_reg, src_reg /* same fake one */, + opcode, is_jmp32); } + if (BPF_SRC(insn->code) == BPF_X && + src_reg->type == SCALAR_VALUE && src_reg->id && + !WARN_ON_ONCE(src_reg->id != other_branch_regs[insn->src_reg].id)) { + find_equal_scalars(this_branch, src_reg); + find_equal_scalars(other_branch, &other_branch_regs[insn->src_reg]); + } if (dst_reg->type == SCALAR_VALUE && dst_reg->id && !WARN_ON_ONCE(dst_reg->id != other_branch_regs[insn->dst_reg].id)) { find_equal_scalars(this_branch, dst_reg); -- cgit v1.2.3 From 9b75dbeb36fcd9fc7ed51d370310d0518a387769 Mon Sep 17 00:00:00 2001 From: Florian Lehner Date: Sun, 5 Nov 2023 09:58:01 +0100 Subject: bpf, lpm: Fix check prefixlen before walking trie When looking up an element in LPM trie, the condition 'matchlen == trie->max_prefixlen' will never return true, if key->prefixlen is larger than trie->max_prefixlen. Consequently all elements in the LPM trie will be visited and no element is returned in the end. To resolve this, check key->prefixlen first before walking the LPM trie. Fixes: b95a5c4db09b ("bpf: add a longest prefix match trie map implementation") Signed-off-by: Florian Lehner Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20231105085801.3742-1-dev@der-flo.net Signed-off-by: Alexei Starovoitov --- kernel/bpf/lpm_trie.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c index 17c7e7782a1f..b32be680da6c 100644 --- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -231,6 +231,9 @@ static void *trie_lookup_elem(struct bpf_map *map, void *_key) struct lpm_trie_node *node, *found = NULL; struct bpf_lpm_trie_key *key = _key; + if (key->prefixlen > trie->max_prefixlen) + return NULL; + /* Start walking the trie from the root node ... */ for (node = rcu_dereference_check(trie->root, rcu_read_lock_bh_held()); -- cgit v1.2.3 From 74523c06ae20b83c5508a98af62393ac34913362 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Mon, 6 Nov 2023 20:57:23 -0800 Subject: bpf: Add __bpf_dynptr_data* for in kernel use Different types of bpf dynptr have different internal data storage. Specifically, SKB and XDP type of dynptr may have non-continuous data. Therefore, it is not always safe to directly access dynptr->data. Add __bpf_dynptr_data and __bpf_dynptr_data_rw to replace direct access to dynptr->data. Update bpf_verify_pkcs7_signature to use __bpf_dynptr_data instead of dynptr->data. Signed-off-by: Song Liu Signed-off-by: Andrii Nakryiko Acked-by: Vadim Fedorenko Link: https://lore.kernel.org/bpf/20231107045725.2278852-2-song@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 2 ++ kernel/bpf/helpers.c | 19 +++++++++++++++++++ kernel/trace/bpf_trace.c | 12 ++++++++---- 3 files changed, 29 insertions(+), 4 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index b4825d3cdb29..eb84caf133df 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1222,6 +1222,8 @@ enum bpf_dynptr_type { int bpf_dynptr_check_size(u32 size); u32 __bpf_dynptr_size(const struct bpf_dynptr_kern *ptr); +const void *__bpf_dynptr_data(const struct bpf_dynptr_kern *ptr, u32 len); +void *__bpf_dynptr_data_rw(const struct bpf_dynptr_kern *ptr, u32 len); #ifdef CONFIG_BPF_JIT int bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr); diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 56b0c1f678ee..174f02a9e703 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2618,3 +2618,22 @@ static int __init kfunc_init(void) } late_initcall(kfunc_init); + +/* Get a pointer to dynptr data up to len bytes for read only access. If + * the dynptr doesn't have continuous data up to len bytes, return NULL. + */ +const void *__bpf_dynptr_data(const struct bpf_dynptr_kern *ptr, u32 len) +{ + return bpf_dynptr_slice(ptr, 0, NULL, len); +} + +/* Get a pointer to dynptr data up to len bytes for read write access. If + * the dynptr doesn't have continuous data up to len bytes, or the dynptr + * is read only, return NULL. + */ +void *__bpf_dynptr_data_rw(const struct bpf_dynptr_kern *ptr, u32 len) +{ + if (__bpf_dynptr_is_rdonly(ptr)) + return NULL; + return (void *)__bpf_dynptr_data(ptr, len); +} diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 84e8a0f6e4e0..f0b8b7c29126 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1376,6 +1376,8 @@ __bpf_kfunc int bpf_verify_pkcs7_signature(struct bpf_dynptr_kern *data_ptr, struct bpf_dynptr_kern *sig_ptr, struct bpf_key *trusted_keyring) { + const void *data, *sig; + u32 data_len, sig_len; int ret; if (trusted_keyring->has_ref) { @@ -1392,10 +1394,12 @@ __bpf_kfunc int bpf_verify_pkcs7_signature(struct bpf_dynptr_kern *data_ptr, return ret; } - return verify_pkcs7_signature(data_ptr->data, - __bpf_dynptr_size(data_ptr), - sig_ptr->data, - __bpf_dynptr_size(sig_ptr), + data_len = __bpf_dynptr_size(data_ptr); + data = __bpf_dynptr_data(data_ptr, data_len); + sig_len = __bpf_dynptr_size(sig_ptr); + sig = __bpf_dynptr_data(sig_ptr, sig_len); + + return verify_pkcs7_signature(data, data_len, sig, sig_len, trusted_keyring->key, VERIFYING_UNSPECIFIED_SIGNATURE, NULL, NULL); -- cgit v1.2.3 From 0b51940729150e807fc4b7767164e6bb6cf4f7dd Mon Sep 17 00:00:00 2001 From: Song Liu Date: Mon, 6 Nov 2023 20:57:24 -0800 Subject: bpf: Factor out helper check_reg_const_str() ARG_PTR_TO_CONST_STR is used to specify constant string args for BPF helpers. The logic that verifies a reg is ARG_PTR_TO_CONST_STR is implemented in check_func_arg(). As we introduce kfuncs with constant string args, it is necessary to do the same check for kfuncs (in check_kfunc_args). Factor out the logic for ARG_PTR_TO_CONST_STR to a new check_reg_const_str() so that it can be reused. check_func_arg() ensures check_reg_const_str() is only called with reg of type PTR_TO_MAP_VALUE. Add a redundent type check in check_reg_const_str() to avoid misuse in the future. Other than this redundent check, there is no change in behavior. Signed-off-by: Song Liu Signed-off-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Acked-by: Vadim Fedorenko Link: https://lore.kernel.org/bpf/20231107045725.2278852-3-song@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 85 +++++++++++++++++++++++++++++---------------------- 1 file changed, 49 insertions(+), 36 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index e801c50d3857..637f34231633 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -8725,6 +8725,54 @@ static enum bpf_dynptr_type dynptr_get_type(struct bpf_verifier_env *env, return state->stack[spi].spilled_ptr.dynptr.type; } +static int check_reg_const_str(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, u32 regno) +{ + struct bpf_map *map = reg->map_ptr; + int err; + int map_off; + u64 map_addr; + char *str_ptr; + + if (reg->type != PTR_TO_MAP_VALUE) + return -EINVAL; + + if (!bpf_map_is_rdonly(map)) { + verbose(env, "R%d does not point to a readonly map'\n", regno); + return -EACCES; + } + + if (!tnum_is_const(reg->var_off)) { + verbose(env, "R%d is not a constant address'\n", regno); + return -EACCES; + } + + if (!map->ops->map_direct_value_addr) { + verbose(env, "no direct value access support for this map type\n"); + return -EACCES; + } + + err = check_map_access(env, regno, reg->off, + map->value_size - reg->off, false, + ACCESS_HELPER); + if (err) + return err; + + map_off = reg->off + reg->var_off.value; + err = map->ops->map_direct_value_addr(map, &map_addr, map_off); + if (err) { + verbose(env, "direct value access on string failed\n"); + return err; + } + + str_ptr = (char *)(long)(map_addr); + if (!strnchr(str_ptr + map_off, map->value_size - map_off, 0)) { + verbose(env, "string is not zero-terminated\n"); + return -EINVAL; + } + return 0; +} + static int check_func_arg(struct bpf_verifier_env *env, u32 arg, struct bpf_call_arg_meta *meta, const struct bpf_func_proto *fn, @@ -8969,44 +9017,9 @@ skip_type_check: } case ARG_PTR_TO_CONST_STR: { - struct bpf_map *map = reg->map_ptr; - int map_off; - u64 map_addr; - char *str_ptr; - - if (!bpf_map_is_rdonly(map)) { - verbose(env, "R%d does not point to a readonly map'\n", regno); - return -EACCES; - } - - if (!tnum_is_const(reg->var_off)) { - verbose(env, "R%d is not a constant address'\n", regno); - return -EACCES; - } - - if (!map->ops->map_direct_value_addr) { - verbose(env, "no direct value access support for this map type\n"); - return -EACCES; - } - - err = check_map_access(env, regno, reg->off, - map->value_size - reg->off, false, - ACCESS_HELPER); + err = check_reg_const_str(env, reg, regno); if (err) return err; - - map_off = reg->off + reg->var_off.value; - err = map->ops->map_direct_value_addr(map, &map_addr, map_off); - if (err) { - verbose(env, "direct value access on string failed\n"); - return err; - } - - str_ptr = (char *)(long)(map_addr); - if (!strnchr(str_ptr + map_off, map->value_size - map_off, 0)) { - verbose(env, "string is not zero-terminated\n"); - return -EINVAL; - } break; } case ARG_PTR_TO_KPTR: -- cgit v1.2.3 From 045edee19d591e59ed53772bf6dfc9b1ed9577eb Mon Sep 17 00:00:00 2001 From: Song Liu Date: Mon, 6 Nov 2023 20:57:25 -0800 Subject: bpf: Introduce KF_ARG_PTR_TO_CONST_STR Similar to ARG_PTR_TO_CONST_STR for BPF helpers, KF_ARG_PTR_TO_CONST_STR specifies kfunc args that point to const strings. Annotation "__str" is used to specify kfunc arg of type KF_ARG_PTR_TO_CONST_STR. Also, add documentation for the "__str" annotation. bpf_get_file_xattr() will be the first kfunc that uses this type. Signed-off-by: Song Liu Signed-off-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Acked-by: Vadim Fedorenko Link: https://lore.kernel.org/bpf/20231107045725.2278852-4-song@kernel.org Signed-off-by: Alexei Starovoitov --- Documentation/bpf/kfuncs.rst | 24 ++++++++++++++++++++++++ kernel/bpf/verifier.c | 19 +++++++++++++++++++ 2 files changed, 43 insertions(+) (limited to 'kernel/bpf') diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst index 723408e399ab..7985c6615f3c 100644 --- a/Documentation/bpf/kfuncs.rst +++ b/Documentation/bpf/kfuncs.rst @@ -135,6 +135,30 @@ Either way, the returned buffer is either NULL, or of size buffer_szk. Without t annotation, the verifier will reject the program if a null pointer is passed in with a nonzero size. +2.2.5 __str Annotation +---------------------------- +This annotation is used to indicate that the argument is a constant string. + +An example is given below:: + + __bpf_kfunc bpf_get_file_xattr(..., const char *name__str, ...) + { + ... + } + +In this case, ``bpf_get_file_xattr()`` can be called as:: + + bpf_get_file_xattr(..., "xattr_name", ...); + +Or:: + + const char name[] = "xattr_name"; /* This need to be global */ + int BPF_PROG(...) + { + ... + bpf_get_file_xattr(..., name, ...); + ... + } .. _BPF_kfunc_nodef: diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 637f34231633..9276e0abcb4b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -10810,6 +10810,11 @@ static bool is_kfunc_arg_nullable(const struct btf *btf, const struct btf_param return __kfunc_param_match_suffix(btf, arg, "__nullable"); } +static bool is_kfunc_arg_const_str(const struct btf *btf, const struct btf_param *arg) +{ + return __kfunc_param_match_suffix(btf, arg, "__str"); +} + static bool is_kfunc_arg_scalar_with_name(const struct btf *btf, const struct btf_param *arg, const char *name) @@ -10953,6 +10958,7 @@ enum kfunc_ptr_arg_type { KF_ARG_PTR_TO_RB_ROOT, KF_ARG_PTR_TO_RB_NODE, KF_ARG_PTR_TO_NULL, + KF_ARG_PTR_TO_CONST_STR, }; enum special_kfunc_type { @@ -11103,6 +11109,9 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env, if (is_kfunc_arg_rbtree_node(meta->btf, &args[argno])) return KF_ARG_PTR_TO_RB_NODE; + if (is_kfunc_arg_const_str(meta->btf, &args[argno])) + return KF_ARG_PTR_TO_CONST_STR; + if ((base_type(reg->type) == PTR_TO_BTF_ID || reg2btf_ids[base_type(reg->type)])) { if (!btf_type_is_struct(ref_t)) { verbose(env, "kernel function %s args#%d pointer type %s %s is not supported\n", @@ -11734,6 +11743,7 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ case KF_ARG_PTR_TO_MEM_SIZE: case KF_ARG_PTR_TO_CALLBACK: case KF_ARG_PTR_TO_REFCOUNTED_KPTR: + case KF_ARG_PTR_TO_CONST_STR: /* Trusted by default */ break; default: @@ -12005,6 +12015,15 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ meta->arg_btf = reg->btf; meta->arg_btf_id = reg->btf_id; break; + case KF_ARG_PTR_TO_CONST_STR: + if (reg->type != PTR_TO_MAP_VALUE) { + verbose(env, "arg#%d doesn't point to a const string\n", i); + return -EINVAL; + } + ret = check_reg_const_str(env, reg, regno); + if (ret) + return ret; + break; } } -- cgit v1.2.3 From 82ce364c6087e31ff9837380a4641a856284064c Mon Sep 17 00:00:00 2001 From: Shung-Hsi Yu Date: Wed, 8 Nov 2023 22:00:41 +0800 Subject: bpf: replace register_is_const() with is_reg_const() The addition of is_reg_const() in commit 171de12646d2 ("bpf: generalize is_branch_taken to handle all conditional jumps in one place") has made the register_is_const() redundant. Give the former has more feature, plus the fact the latter is only used in one place, replace register_is_const() with is_reg_const(), and remove the definition of register_is_const. This requires moving the definition of is_reg_const() further up. And since the comment of reg_const_value() reference is_reg_const(), move it up as well. Signed-off-by: Shung-Hsi Yu Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231108140043.12282-1-shung-hsi.yu@suse.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 27 +++++++++++---------------- 1 file changed, 11 insertions(+), 16 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9276e0abcb4b..993e4677bbe9 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4690,9 +4690,17 @@ static bool register_is_null(struct bpf_reg_state *reg) return reg->type == SCALAR_VALUE && tnum_equals_const(reg->var_off, 0); } -static bool register_is_const(struct bpf_reg_state *reg) +/* check if register is a constant scalar value */ +static bool is_reg_const(struct bpf_reg_state *reg, bool subreg32) +{ + return reg->type == SCALAR_VALUE && + tnum_is_const(subreg32 ? tnum_subreg(reg->var_off) : reg->var_off); +} + +/* assuming is_reg_const() is true, return constant value of a register */ +static u64 reg_const_value(struct bpf_reg_state *reg, bool subreg32) { - return reg->type == SCALAR_VALUE && tnum_is_const(reg->var_off); + return subreg32 ? tnum_subreg(reg->var_off).value : reg->var_off.value; } static bool __is_scalar_unbounded(struct bpf_reg_state *reg) @@ -10050,7 +10058,7 @@ record_func_key(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta, val = reg->var_off.value; max = map->max_entries; - if (!(register_is_const(reg) && val < max)) { + if (!(is_reg_const(reg, false) && val < max)) { bpf_map_key_store(aux, BPF_MAP_KEY_POISON); return 0; } @@ -14220,19 +14228,6 @@ static void find_good_pkt_pointers(struct bpf_verifier_state *vstate, })); } -/* check if register is a constant scalar value */ -static bool is_reg_const(struct bpf_reg_state *reg, bool subreg32) -{ - return reg->type == SCALAR_VALUE && - tnum_is_const(subreg32 ? tnum_subreg(reg->var_off) : reg->var_off); -} - -/* assuming is_reg_const() is true, return constant value of a register */ -static u64 reg_const_value(struct bpf_reg_state *reg, bool subreg32) -{ - return subreg32 ? tnum_subreg(reg->var_off).value : reg->var_off.value; -} - /* * , currently assuming reg2 is a constant */ -- cgit v1.2.3 From 1500a5d9f49cb66906d3ea1c9158df25cc41dd40 Mon Sep 17 00:00:00 2001 From: Dave Marchevsky Date: Tue, 7 Nov 2023 00:56:34 -0800 Subject: bpf: Add KF_RCU flag to bpf_refcount_acquire_impl Refcounted local kptrs are kptrs to user-defined types with a bpf_refcount field. Recent commits ([0], [1]) modified the lifetime of refcounted local kptrs such that the underlying memory is not reused until RCU grace period has elapsed. Separately, verification of bpf_refcount_acquire calls currently succeeds for MAYBE_NULL non-owning reference input, which is a problem as bpf_refcount_acquire_impl has no handling for this case. This patch takes advantage of aforementioned lifetime changes to tag bpf_refcount_acquire_impl kfunc KF_RCU, thereby preventing MAYBE_NULL input to the kfunc. The KF_RCU flag applies to all kfunc params; it's fine for it to apply to the void *meta__ign param as that's populated by the verifier and is tagged __ign regardless. [0]: commit 7e26cd12ad1c ("bpf: Use bpf_mem_free_rcu when bpf_obj_dropping refcounted nodes") is the actual change to allocation behaivor [1]: commit 0816b8c6bf7f ("bpf: Consider non-owning refs to refcounted nodes RCU protected") modified verifier understanding of refcounted local kptrs to match [0]'s changes Signed-off-by: Dave Marchevsky Fixes: 7c50b1cb76ac ("bpf: Add bpf_refcount_acquire kfunc") Link: https://lore.kernel.org/r/20231107085639.3016113-2-davemarchevsky@fb.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/helpers.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 174f02a9e703..b84d8cb8d239 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2520,7 +2520,7 @@ BTF_ID_FLAGS(func, bpf_obj_new_impl, KF_ACQUIRE | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_percpu_obj_new_impl, KF_ACQUIRE | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_obj_drop_impl, KF_RELEASE) BTF_ID_FLAGS(func, bpf_percpu_obj_drop_impl, KF_RELEASE) -BTF_ID_FLAGS(func, bpf_refcount_acquire_impl, KF_ACQUIRE | KF_RET_NULL) +BTF_ID_FLAGS(func, bpf_refcount_acquire_impl, KF_ACQUIRE | KF_RET_NULL | KF_RCU) BTF_ID_FLAGS(func, bpf_list_push_front_impl) BTF_ID_FLAGS(func, bpf_list_push_back_impl) BTF_ID_FLAGS(func, bpf_list_pop_front, KF_ACQUIRE | KF_RET_NULL) -- cgit v1.2.3 From 649924b76ab151a96bdd22a97a993fb0421f134c Mon Sep 17 00:00:00 2001 From: Dave Marchevsky Date: Tue, 7 Nov 2023 00:56:36 -0800 Subject: bpf: Use bpf_mem_free_rcu when bpf_obj_dropping non-refcounted nodes The use of bpf_mem_free_rcu to free refcounted local kptrs was added in commit 7e26cd12ad1c ("bpf: Use bpf_mem_free_rcu when bpf_obj_dropping refcounted nodes"). In the cover letter for the series containing that patch [0] I commented: Perhaps it makes sense to move to mem_free_rcu for _all_ non-owning refs in the future, not just refcounted. This might allow custom non-owning ref lifetime + invalidation logic to be entirely subsumed by MEM_RCU handling. IMO this needs a bit more thought and should be tackled outside of a fix series, so it's not attempted here. It's time to start moving in the "non-owning refs have MEM_RCU lifetime" direction. As mentioned in that comment, using bpf_mem_free_rcu for all local kptrs - not just refcounted - is necessarily the first step towards that goal. This patch does so. After this patch the memory pointed to by all local kptrs will not be reused until RCU grace period elapses. The verifier's understanding of non-owning ref validity and the clobbering logic it uses to enforce that understanding are not changed here, that'll happen gradually in future work, including further patches in the series. [0]: https://lore.kernel.org/all/20230821193311.3290257-1-davemarchevsky@fb.com/ Signed-off-by: Dave Marchevsky Link: https://lore.kernel.org/r/20231107085639.3016113-4-davemarchevsky@fb.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/helpers.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index b84d8cb8d239..03517db5cfb3 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -1937,10 +1937,7 @@ void __bpf_obj_drop_impl(void *p, const struct btf_record *rec, bool percpu) ma = &bpf_global_percpu_ma; else ma = &bpf_global_ma; - if (rec && rec->refcount_off >= 0) - bpf_mem_free_rcu(ma, p); - else - bpf_mem_free(ma, p); + bpf_mem_free_rcu(ma, p); } __bpf_kfunc void bpf_obj_drop_impl(void *p__alloc, void *meta__ign) -- cgit v1.2.3 From 790ce3cfefb1b768dccd4eee324ddef0f0ce3db4 Mon Sep 17 00:00:00 2001 From: Dave Marchevsky Date: Tue, 7 Nov 2023 00:56:37 -0800 Subject: bpf: Move GRAPH_{ROOT,NODE}_MASK macros into btf_field_type enum This refactoring patch removes the unused BPF_GRAPH_NODE_OR_ROOT btf_field_type and moves BPF_GRAPH_{NODE,ROOT} macros into the btf_field_type enum. Further patches in the series will use BPF_GRAPH_NODE, so let's move this useful definition out of btf.c. Signed-off-by: Dave Marchevsky Link: https://lore.kernel.org/r/20231107085639.3016113-5-davemarchevsky@fb.com Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 4 ++-- kernel/bpf/btf.c | 11 ++++------- 2 files changed, 6 insertions(+), 9 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index eb84caf133df..4001d11be151 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -186,8 +186,8 @@ enum btf_field_type { BPF_LIST_NODE = (1 << 6), BPF_RB_ROOT = (1 << 7), BPF_RB_NODE = (1 << 8), - BPF_GRAPH_NODE_OR_ROOT = BPF_LIST_NODE | BPF_LIST_HEAD | - BPF_RB_NODE | BPF_RB_ROOT, + BPF_GRAPH_NODE = BPF_RB_NODE | BPF_LIST_NODE, + BPF_GRAPH_ROOT = BPF_RB_ROOT | BPF_LIST_HEAD, BPF_REFCOUNT = (1 << 9), }; diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 15d71d2986d3..63cf4128fc05 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -3840,9 +3840,6 @@ end: return ERR_PTR(ret); } -#define GRAPH_ROOT_MASK (BPF_LIST_HEAD | BPF_RB_ROOT) -#define GRAPH_NODE_MASK (BPF_LIST_NODE | BPF_RB_NODE) - int btf_check_and_fixup_fields(const struct btf *btf, struct btf_record *rec) { int i; @@ -3855,13 +3852,13 @@ int btf_check_and_fixup_fields(const struct btf *btf, struct btf_record *rec) * Hence we only need to ensure that bpf_{list_head,rb_root} ownership * does not form cycles. */ - if (IS_ERR_OR_NULL(rec) || !(rec->field_mask & GRAPH_ROOT_MASK)) + if (IS_ERR_OR_NULL(rec) || !(rec->field_mask & BPF_GRAPH_ROOT)) return 0; for (i = 0; i < rec->cnt; i++) { struct btf_struct_meta *meta; u32 btf_id; - if (!(rec->fields[i].type & GRAPH_ROOT_MASK)) + if (!(rec->fields[i].type & BPF_GRAPH_ROOT)) continue; btf_id = rec->fields[i].graph_root.value_btf_id; meta = btf_find_struct_meta(btf, btf_id); @@ -3873,7 +3870,7 @@ int btf_check_and_fixup_fields(const struct btf *btf, struct btf_record *rec) * to check ownership cycle for a type unless it's also a * node type. */ - if (!(rec->field_mask & GRAPH_NODE_MASK)) + if (!(rec->field_mask & BPF_GRAPH_NODE)) continue; /* We need to ensure ownership acyclicity among all types. The @@ -3909,7 +3906,7 @@ int btf_check_and_fixup_fields(const struct btf *btf, struct btf_record *rec) * - A is both an root and node. * - B is only an node. */ - if (meta->record->field_mask & GRAPH_ROOT_MASK) + if (meta->record->field_mask & BPF_GRAPH_ROOT) return -ELOOP; } return 0; -- cgit v1.2.3 From 1b12171533a9bb23cf6fba7262b479028b65e1e8 Mon Sep 17 00:00:00 2001 From: Dave Marchevsky Date: Tue, 7 Nov 2023 00:56:38 -0800 Subject: bpf: Mark direct ld of stashed bpf_{rb,list}_node as non-owning ref This patch enables the following pattern: /* mapval contains a __kptr pointing to refcounted local kptr */ mapval = bpf_map_lookup_elem(&map, &idx); if (!mapval || !mapval->some_kptr) { /* omitted */ } p = bpf_refcount_acquire(&mapval->some_kptr); Currently this doesn't work because bpf_refcount_acquire expects an owning or non-owning ref. The verifier defines non-owning ref as a type: PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF while mapval->some_kptr is PTR_TO_BTF_ID | PTR_UNTRUSTED. It's possible to do the refcount_acquire by first bpf_kptr_xchg'ing mapval->some_kptr into a temp kptr, refcount_acquiring that, and xchg'ing back into mapval, but this is unwieldy and shouldn't be necessary. This patch modifies btf_ld_kptr_type such that user-allocated types are marked MEM_ALLOC and if those types have a bpf_{rb,list}_node they're marked NON_OWN_REF as well. Additionally, due to changes to bpf_obj_drop_impl earlier in this series, rcu_protected_object now returns true for all user-allocated types, resulting in mapval->some_kptr being marked MEM_RCU. After this patch's changes, mapval->some_kptr is now: PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF | MEM_RCU which results in it passing the non-owning ref test, and the motivating example passing verification. Future work will likely get rid of special non-owning ref lifetime logic in the verifier, at which point we'll be able to delete the NON_OWN_REF flag entirely. Signed-off-by: Dave Marchevsky Link: https://lore.kernel.org/r/20231107085639.3016113-6-davemarchevsky@fb.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 36 +++++++++++++++++++++++++++++++----- 1 file changed, 31 insertions(+), 5 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 993e4677bbe9..9ae6eae13471 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5557,10 +5557,23 @@ BTF_SET_END(rcu_protected_types) static bool rcu_protected_object(const struct btf *btf, u32 btf_id) { if (!btf_is_kernel(btf)) - return false; + return true; return btf_id_set_contains(&rcu_protected_types, btf_id); } +static struct btf_record *kptr_pointee_btf_record(struct btf_field *kptr_field) +{ + struct btf_struct_meta *meta; + + if (btf_is_kernel(kptr_field->kptr.btf)) + return NULL; + + meta = btf_find_struct_meta(kptr_field->kptr.btf, + kptr_field->kptr.btf_id); + + return meta ? meta->record : NULL; +} + static bool rcu_safe_kptr(const struct btf_field *field) { const struct btf_field_kptr *kptr = &field->kptr; @@ -5571,12 +5584,25 @@ static bool rcu_safe_kptr(const struct btf_field *field) static u32 btf_ld_kptr_type(struct bpf_verifier_env *env, struct btf_field *kptr_field) { + struct btf_record *rec; + u32 ret; + + ret = PTR_MAYBE_NULL; if (rcu_safe_kptr(kptr_field) && in_rcu_cs(env)) { - if (kptr_field->type != BPF_KPTR_PERCPU) - return PTR_MAYBE_NULL | MEM_RCU; - return PTR_MAYBE_NULL | MEM_RCU | MEM_PERCPU; + ret |= MEM_RCU; + if (kptr_field->type == BPF_KPTR_PERCPU) + ret |= MEM_PERCPU; + else if (!btf_is_kernel(kptr_field->kptr.btf)) + ret |= MEM_ALLOC; + + rec = kptr_pointee_btf_record(kptr_field); + if (rec && btf_record_has_field(rec, BPF_GRAPH_NODE)) + ret |= NON_OWN_REF; + } else { + ret |= PTR_UNTRUSTED; } - return PTR_MAYBE_NULL | PTR_UNTRUSTED; + + return ret; } static int check_map_kptr_access(struct bpf_verifier_env *env, u32 regno, -- cgit v1.2.3 From b8e3a87a627b575896e448021e5c2f8a3bc19931 Mon Sep 17 00:00:00 2001 From: Jordan Rome Date: Wed, 8 Nov 2023 03:23:34 -0800 Subject: bpf: Add crosstask check to __bpf_get_stack Currently get_perf_callchain only supports user stack walking for the current task. Passing the correct *crosstask* param will return 0 frames if the task passed to __bpf_get_stack isn't the current one instead of a single incorrect frame/address. This change passes the correct *crosstask* param but also does a preemptive check in __bpf_get_stack if the task is current and returns -EOPNOTSUPP if it is not. This issue was found using bpf_get_task_stack inside a BPF iterator ("iter/task"), which iterates over all tasks. bpf_get_task_stack works fine for fetching kernel stacks but because get_perf_callchain relies on the caller to know if the requested *task* is the current one (via *crosstask*) it was failing in a confusing way. It might be possible to get user stacks for all tasks utilizing something like access_process_vm but that requires the bpf program calling bpf_get_task_stack to be sleepable and would therefore be a breaking change. Fixes: fa28dcb82a38 ("bpf: Introduce helper bpf_get_task_stack()") Signed-off-by: Jordan Rome Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20231108112334.3433136-1-jordalgo@meta.com --- include/uapi/linux/bpf.h | 3 +++ kernel/bpf/stackmap.c | 11 ++++++++++- tools/include/uapi/linux/bpf.h | 3 +++ 3 files changed, 16 insertions(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 095ca7238ac2..7cf8bcf9f6a2 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -4517,6 +4517,8 @@ union bpf_attr { * long bpf_get_task_stack(struct task_struct *task, void *buf, u32 size, u64 flags) * Description * Return a user or a kernel stack in bpf program provided buffer. + * Note: the user stack will only be populated if the *task* is + * the current task; all other tasks will return -EOPNOTSUPP. * To achieve this, the helper needs *task*, which is a valid * pointer to **struct task_struct**. To store the stacktrace, the * bpf program provides *buf* with a nonnegative *size*. @@ -4528,6 +4530,7 @@ union bpf_attr { * * **BPF_F_USER_STACK** * Collect a user space stack instead of a kernel stack. + * The *task* must be the current task. * **BPF_F_USER_BUILD_ID** * Collect buildid+offset instead of ips for user stack, * only valid if **BPF_F_USER_STACK** is also specified. diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index d6b277482085..dff7ba539701 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -388,6 +388,7 @@ static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task, { u32 trace_nr, copy_len, elem_size, num_elem, max_depth; bool user_build_id = flags & BPF_F_USER_BUILD_ID; + bool crosstask = task && task != current; u32 skip = flags & BPF_F_SKIP_FIELD_MASK; bool user = flags & BPF_F_USER_STACK; struct perf_callchain_entry *trace; @@ -410,6 +411,14 @@ static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task, if (task && user && !user_mode(regs)) goto err_fault; + /* get_perf_callchain does not support crosstask user stack walking + * but returns an empty stack instead of NULL. + */ + if (crosstask && user) { + err = -EOPNOTSUPP; + goto clear; + } + num_elem = size / elem_size; max_depth = num_elem + skip; if (sysctl_perf_event_max_stack < max_depth) @@ -421,7 +430,7 @@ static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task, trace = get_callchain_entry_for_task(task, max_depth); else trace = get_perf_callchain(regs, 0, kernel, user, max_depth, - false, false); + crosstask, false); if (unlikely(!trace)) goto err_fault; diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 095ca7238ac2..7cf8bcf9f6a2 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -4517,6 +4517,8 @@ union bpf_attr { * long bpf_get_task_stack(struct task_struct *task, void *buf, u32 size, u64 flags) * Description * Return a user or a kernel stack in bpf program provided buffer. + * Note: the user stack will only be populated if the *task* is + * the current task; all other tasks will return -EOPNOTSUPP. * To achieve this, the helper needs *task*, which is a valid * pointer to **struct task_struct**. To store the stacktrace, the * bpf program provides *buf* with a nonnegative *size*. @@ -4528,6 +4530,7 @@ union bpf_attr { * * **BPF_F_USER_STACK** * Collect a user space stack instead of a kernel stack. + * The *task* must be the current task. * **BPF_F_USER_BUILD_ID** * Collect buildid+offset instead of ips for user stack, * only valid if **BPF_F_USER_STACK** is also specified. -- cgit v1.2.3 From fe977716b40cb98cf9c91a66454adf3dc2f8c59a Mon Sep 17 00:00:00 2001 From: Yafang Shao Date: Sat, 11 Nov 2023 09:00:29 +0000 Subject: bpf: Add a new kfunc for cgroup1 hierarchy A new kfunc is added to acquire cgroup1 of a task: - bpf_task_get_cgroup1 Acquires the associated cgroup of a task whithin a specific cgroup1 hierarchy. The cgroup1 hierarchy is identified by its hierarchy ID. This new kfunc enables the tracing of tasks within a designated container or cgroup directory in BPF programs. Suggested-by: Tejun Heo Signed-off-by: Yafang Shao Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20231111090034.4248-2-laoar.shao@gmail.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/helpers.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 03517db5cfb3..b45a8381f9bd 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2228,6 +2228,25 @@ __bpf_kfunc long bpf_task_under_cgroup(struct task_struct *task, rcu_read_unlock(); return ret; } + +/** + * bpf_task_get_cgroup1 - Acquires the associated cgroup of a task within a + * specific cgroup1 hierarchy. The cgroup1 hierarchy is identified by its + * hierarchy ID. + * @task: The target task + * @hierarchy_id: The ID of a cgroup1 hierarchy + * + * On success, the cgroup is returen. On failure, NULL is returned. + */ +__bpf_kfunc struct cgroup * +bpf_task_get_cgroup1(struct task_struct *task, int hierarchy_id) +{ + struct cgroup *cgrp = task_get_cgroup1(task, hierarchy_id); + + if (IS_ERR(cgrp)) + return NULL; + return cgrp; +} #endif /* CONFIG_CGROUPS */ /** @@ -2534,6 +2553,7 @@ BTF_ID_FLAGS(func, bpf_cgroup_release, KF_RELEASE) BTF_ID_FLAGS(func, bpf_cgroup_ancestor, KF_ACQUIRE | KF_RCU | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_cgroup_from_id, KF_ACQUIRE | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_task_under_cgroup, KF_RCU) +BTF_ID_FLAGS(func, bpf_task_get_cgroup1, KF_ACQUIRE | KF_RCU | KF_RET_NULL) #endif BTF_ID_FLAGS(func, bpf_task_from_pid, KF_ACQUIRE | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_throw) -- cgit v1.2.3 From 67420501e8681ae18f9f0ea0a69cd2f432100e70 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sat, 11 Nov 2023 17:05:57 -0800 Subject: bpf: generalize reg_set_min_max() to handle non-const register comparisons Generalize bounds adjustment logic of reg_set_min_max() to handle not just register vs constant case, but in general any register vs any register cases. For most of the operations it's trivial extension based on range vs range comparison logic, we just need to properly pick min/max of a range to compare against min/max of the other range. For BPF_JSET we keep the original capabilities, just make sure JSET is integrated in the common framework. This is manifested in the internal-only BPF_JSET + BPF_X "opcode" to allow for simpler and more uniform rev_opcode() handling. See the code for details. This allows to reuse the same code exactly both for TRUE and FALSE branches without explicitly handling both conditions with custom code. Note also that now we don't need a special handling of BPF_JEQ/BPF_JNE case none of the registers are constants. This is now just a normal generic case handled by reg_set_min_max(). To make tnum handling cleaner, tnum_with_subreg() helper is added, as that's a common operator when dealing with 32-bit subregister bounds. This keeps the overall logic much less noisy when it comes to tnums. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Acked-by: Shung-Hsi Yu Link: https://lore.kernel.org/r/20231112010609.848406-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/tnum.h | 4 + kernel/bpf/tnum.c | 7 +- kernel/bpf/verifier.c | 314 ++++++++++++++++++++++---------------------------- 3 files changed, 146 insertions(+), 179 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/tnum.h b/include/linux/tnum.h index 1c3948a1d6ad..3c13240077b8 100644 --- a/include/linux/tnum.h +++ b/include/linux/tnum.h @@ -106,6 +106,10 @@ int tnum_sbin(char *str, size_t size, struct tnum a); struct tnum tnum_subreg(struct tnum a); /* Returns the tnum with the lower 32-bit subreg cleared */ struct tnum tnum_clear_subreg(struct tnum a); +/* Returns the tnum with the lower 32-bit subreg in *reg* set to the lower + * 32-bit subreg in *subreg* + */ +struct tnum tnum_with_subreg(struct tnum reg, struct tnum subreg); /* Returns the tnum with the lower 32-bit subreg set to value */ struct tnum tnum_const_subreg(struct tnum a, u32 value); /* Returns true if 32-bit subreg @a is a known constant*/ diff --git a/kernel/bpf/tnum.c b/kernel/bpf/tnum.c index 3d7127f439a1..f4c91c9b27d7 100644 --- a/kernel/bpf/tnum.c +++ b/kernel/bpf/tnum.c @@ -208,7 +208,12 @@ struct tnum tnum_clear_subreg(struct tnum a) return tnum_lshift(tnum_rshift(a, 32), 32); } +struct tnum tnum_with_subreg(struct tnum reg, struct tnum subreg) +{ + return tnum_or(tnum_clear_subreg(reg), tnum_subreg(subreg)); +} + struct tnum tnum_const_subreg(struct tnum a, u32 value) { - return tnum_or(tnum_clear_subreg(a), tnum_const(value)); + return tnum_with_subreg(a, tnum_const(value)); } diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9ae6eae13471..39ce141c55d3 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14453,218 +14453,186 @@ static int is_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg return is_scalar_branch_taken(reg1, reg2, opcode, is_jmp32); } -/* Adjusts the register min/max values in the case that the dst_reg and - * src_reg are both SCALAR_VALUE registers (or we are simply doing a BPF_K - * check, in which case we havea fake SCALAR_VALUE representing insn->imm). - * Technically we can do similar adjustments for pointers to the same object, - * but we don't support that right now. +/* Opcode that corresponds to a *false* branch condition. + * E.g., if r1 < r2, then reverse (false) condition is r1 >= r2 */ -static void reg_set_min_max(struct bpf_reg_state *true_reg1, - struct bpf_reg_state *true_reg2, - struct bpf_reg_state *false_reg1, - struct bpf_reg_state *false_reg2, - u8 opcode, bool is_jmp32) +static u8 rev_opcode(u8 opcode) { - struct tnum false_32off, false_64off; - struct tnum true_32off, true_64off; - u64 uval; - u32 uval32; - s64 sval; - s32 sval32; - - /* If either register is a pointer, we can't learn anything about its - * variable offset from the compare (unless they were a pointer into - * the same object, but we don't bother with that). + switch (opcode) { + case BPF_JEQ: return BPF_JNE; + case BPF_JNE: return BPF_JEQ; + /* JSET doesn't have it's reverse opcode in BPF, so add + * BPF_X flag to denote the reverse of that operation */ - if (false_reg1->type != SCALAR_VALUE || false_reg2->type != SCALAR_VALUE) - return; - - /* we expect right-hand registers (src ones) to be constants, for now */ - if (!is_reg_const(false_reg2, is_jmp32)) { - opcode = flip_opcode(opcode); - swap(true_reg1, true_reg2); - swap(false_reg1, false_reg2); + case BPF_JSET: return BPF_JSET | BPF_X; + case BPF_JSET | BPF_X: return BPF_JSET; + case BPF_JGE: return BPF_JLT; + case BPF_JGT: return BPF_JLE; + case BPF_JLE: return BPF_JGT; + case BPF_JLT: return BPF_JGE; + case BPF_JSGE: return BPF_JSLT; + case BPF_JSGT: return BPF_JSLE; + case BPF_JSLE: return BPF_JSGT; + case BPF_JSLT: return BPF_JSGE; + default: return 0; } - if (!is_reg_const(false_reg2, is_jmp32)) - return; +} - false_32off = tnum_subreg(false_reg1->var_off); - false_64off = false_reg1->var_off; - true_32off = tnum_subreg(true_reg1->var_off); - true_64off = true_reg1->var_off; - uval = false_reg2->var_off.value; - uval32 = (u32)tnum_subreg(false_reg2->var_off).value; - sval = (s64)uval; - sval32 = (s32)uval32; +/* Refine range knowledge for 2 conditional operation. */ +static void regs_refine_cond_op(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, + u8 opcode, bool is_jmp32) +{ + struct tnum t; + u64 val; +again: switch (opcode) { - /* JEQ/JNE comparison doesn't change the register equivalence. - * - * r1 = r2; - * if (r1 == 42) goto label; - * ... - * label: // here both r1 and r2 are known to be 42. - * - * Hence when marking register as known preserve it's ID. - */ case BPF_JEQ: if (is_jmp32) { - __mark_reg32_known(true_reg1, uval32); - true_32off = tnum_subreg(true_reg1->var_off); + reg1->u32_min_value = max(reg1->u32_min_value, reg2->u32_min_value); + reg1->u32_max_value = min(reg1->u32_max_value, reg2->u32_max_value); + reg1->s32_min_value = max(reg1->s32_min_value, reg2->s32_min_value); + reg1->s32_max_value = min(reg1->s32_max_value, reg2->s32_max_value); + reg2->u32_min_value = reg1->u32_min_value; + reg2->u32_max_value = reg1->u32_max_value; + reg2->s32_min_value = reg1->s32_min_value; + reg2->s32_max_value = reg1->s32_max_value; + + t = tnum_intersect(tnum_subreg(reg1->var_off), tnum_subreg(reg2->var_off)); + reg1->var_off = tnum_with_subreg(reg1->var_off, t); + reg2->var_off = tnum_with_subreg(reg2->var_off, t); } else { - ___mark_reg_known(true_reg1, uval); - true_64off = true_reg1->var_off; + reg1->umin_value = max(reg1->umin_value, reg2->umin_value); + reg1->umax_value = min(reg1->umax_value, reg2->umax_value); + reg1->smin_value = max(reg1->smin_value, reg2->smin_value); + reg1->smax_value = min(reg1->smax_value, reg2->smax_value); + reg2->umin_value = reg1->umin_value; + reg2->umax_value = reg1->umax_value; + reg2->smin_value = reg1->smin_value; + reg2->smax_value = reg1->smax_value; + + reg1->var_off = tnum_intersect(reg1->var_off, reg2->var_off); + reg2->var_off = reg1->var_off; } break; case BPF_JNE: - if (is_jmp32) { - __mark_reg32_known(false_reg1, uval32); - false_32off = tnum_subreg(false_reg1->var_off); - } else { - ___mark_reg_known(false_reg1, uval); - false_64off = false_reg1->var_off; - } + /* we don't derive any new information for inequality yet */ break; case BPF_JSET: + if (!is_reg_const(reg2, is_jmp32)) + swap(reg1, reg2); + if (!is_reg_const(reg2, is_jmp32)) + break; + val = reg_const_value(reg2, is_jmp32); + /* BPF_JSET (i.e., TRUE branch, *not* BPF_JSET | BPF_X) + * requires single bit to learn something useful. E.g., if we + * know that `r1 & 0x3` is true, then which bits (0, 1, or both) + * are actually set? We can learn something definite only if + * it's a single-bit value to begin with. + * + * BPF_JSET | BPF_X (i.e., negation of BPF_JSET) doesn't have + * this restriction. I.e., !(r1 & 0x3) means neither bit 0 nor + * bit 1 is set, which we can readily use in adjustments. + */ + if (!is_power_of_2(val)) + break; if (is_jmp32) { - false_32off = tnum_and(false_32off, tnum_const(~uval32)); - if (is_power_of_2(uval32)) - true_32off = tnum_or(true_32off, - tnum_const(uval32)); + t = tnum_or(tnum_subreg(reg1->var_off), tnum_const(val)); + reg1->var_off = tnum_with_subreg(reg1->var_off, t); } else { - false_64off = tnum_and(false_64off, tnum_const(~uval)); - if (is_power_of_2(uval)) - true_64off = tnum_or(true_64off, - tnum_const(uval)); + reg1->var_off = tnum_or(reg1->var_off, tnum_const(val)); } break; - case BPF_JGE: - case BPF_JGT: - { + case BPF_JSET | BPF_X: /* reverse of BPF_JSET, see rev_opcode() */ + if (!is_reg_const(reg2, is_jmp32)) + swap(reg1, reg2); + if (!is_reg_const(reg2, is_jmp32)) + break; + val = reg_const_value(reg2, is_jmp32); if (is_jmp32) { - u32 false_umax = opcode == BPF_JGT ? uval32 : uval32 - 1; - u32 true_umin = opcode == BPF_JGT ? uval32 + 1 : uval32; - - false_reg1->u32_max_value = min(false_reg1->u32_max_value, - false_umax); - true_reg1->u32_min_value = max(true_reg1->u32_min_value, - true_umin); + t = tnum_and(tnum_subreg(reg1->var_off), tnum_const(~val)); + reg1->var_off = tnum_with_subreg(reg1->var_off, t); } else { - u64 false_umax = opcode == BPF_JGT ? uval : uval - 1; - u64 true_umin = opcode == BPF_JGT ? uval + 1 : uval; - - false_reg1->umax_value = min(false_reg1->umax_value, false_umax); - true_reg1->umin_value = max(true_reg1->umin_value, true_umin); + reg1->var_off = tnum_and(reg1->var_off, tnum_const(~val)); } break; - } - case BPF_JSGE: - case BPF_JSGT: - { + case BPF_JLE: if (is_jmp32) { - s32 false_smax = opcode == BPF_JSGT ? sval32 : sval32 - 1; - s32 true_smin = opcode == BPF_JSGT ? sval32 + 1 : sval32; - - false_reg1->s32_max_value = min(false_reg1->s32_max_value, false_smax); - true_reg1->s32_min_value = max(true_reg1->s32_min_value, true_smin); + reg1->u32_max_value = min(reg1->u32_max_value, reg2->u32_max_value); + reg2->u32_min_value = max(reg1->u32_min_value, reg2->u32_min_value); } else { - s64 false_smax = opcode == BPF_JSGT ? sval : sval - 1; - s64 true_smin = opcode == BPF_JSGT ? sval + 1 : sval; - - false_reg1->smax_value = min(false_reg1->smax_value, false_smax); - true_reg1->smin_value = max(true_reg1->smin_value, true_smin); + reg1->umax_value = min(reg1->umax_value, reg2->umax_value); + reg2->umin_value = max(reg1->umin_value, reg2->umin_value); } break; - } - case BPF_JLE: case BPF_JLT: - { if (is_jmp32) { - u32 false_umin = opcode == BPF_JLT ? uval32 : uval32 + 1; - u32 true_umax = opcode == BPF_JLT ? uval32 - 1 : uval32; - - false_reg1->u32_min_value = max(false_reg1->u32_min_value, - false_umin); - true_reg1->u32_max_value = min(true_reg1->u32_max_value, - true_umax); + reg1->u32_max_value = min(reg1->u32_max_value, reg2->u32_max_value - 1); + reg2->u32_min_value = max(reg1->u32_min_value + 1, reg2->u32_min_value); } else { - u64 false_umin = opcode == BPF_JLT ? uval : uval + 1; - u64 true_umax = opcode == BPF_JLT ? uval - 1 : uval; - - false_reg1->umin_value = max(false_reg1->umin_value, false_umin); - true_reg1->umax_value = min(true_reg1->umax_value, true_umax); + reg1->umax_value = min(reg1->umax_value, reg2->umax_value - 1); + reg2->umin_value = max(reg1->umin_value + 1, reg2->umin_value); } break; - } case BPF_JSLE: + if (is_jmp32) { + reg1->s32_max_value = min(reg1->s32_max_value, reg2->s32_max_value); + reg2->s32_min_value = max(reg1->s32_min_value, reg2->s32_min_value); + } else { + reg1->smax_value = min(reg1->smax_value, reg2->smax_value); + reg2->smin_value = max(reg1->smin_value, reg2->smin_value); + } + break; case BPF_JSLT: - { if (is_jmp32) { - s32 false_smin = opcode == BPF_JSLT ? sval32 : sval32 + 1; - s32 true_smax = opcode == BPF_JSLT ? sval32 - 1 : sval32; - - false_reg1->s32_min_value = max(false_reg1->s32_min_value, false_smin); - true_reg1->s32_max_value = min(true_reg1->s32_max_value, true_smax); + reg1->s32_max_value = min(reg1->s32_max_value, reg2->s32_max_value - 1); + reg2->s32_min_value = max(reg1->s32_min_value + 1, reg2->s32_min_value); } else { - s64 false_smin = opcode == BPF_JSLT ? sval : sval + 1; - s64 true_smax = opcode == BPF_JSLT ? sval - 1 : sval; - - false_reg1->smin_value = max(false_reg1->smin_value, false_smin); - true_reg1->smax_value = min(true_reg1->smax_value, true_smax); + reg1->smax_value = min(reg1->smax_value, reg2->smax_value - 1); + reg2->smin_value = max(reg1->smin_value + 1, reg2->smin_value); } break; - } + case BPF_JGE: + case BPF_JGT: + case BPF_JSGE: + case BPF_JSGT: + /* just reuse LE/LT logic above */ + opcode = flip_opcode(opcode); + swap(reg1, reg2); + goto again; default: return; } - - if (is_jmp32) { - false_reg1->var_off = tnum_or(tnum_clear_subreg(false_64off), - tnum_subreg(false_32off)); - true_reg1->var_off = tnum_or(tnum_clear_subreg(true_64off), - tnum_subreg(true_32off)); - reg_bounds_sync(false_reg1); - reg_bounds_sync(true_reg1); - } else { - false_reg1->var_off = false_64off; - true_reg1->var_off = true_64off; - reg_bounds_sync(false_reg1); - reg_bounds_sync(true_reg1); - } -} - -/* Regs are known to be equal, so intersect their min/max/var_off */ -static void __reg_combine_min_max(struct bpf_reg_state *src_reg, - struct bpf_reg_state *dst_reg) -{ - src_reg->umin_value = dst_reg->umin_value = max(src_reg->umin_value, - dst_reg->umin_value); - src_reg->umax_value = dst_reg->umax_value = min(src_reg->umax_value, - dst_reg->umax_value); - src_reg->smin_value = dst_reg->smin_value = max(src_reg->smin_value, - dst_reg->smin_value); - src_reg->smax_value = dst_reg->smax_value = min(src_reg->smax_value, - dst_reg->smax_value); - src_reg->var_off = dst_reg->var_off = tnum_intersect(src_reg->var_off, - dst_reg->var_off); - reg_bounds_sync(src_reg); - reg_bounds_sync(dst_reg); } -static void reg_combine_min_max(struct bpf_reg_state *true_src, - struct bpf_reg_state *true_dst, - struct bpf_reg_state *false_src, - struct bpf_reg_state *false_dst, - u8 opcode) +/* Adjusts the register min/max values in the case that the dst_reg and + * src_reg are both SCALAR_VALUE registers (or we are simply doing a BPF_K + * check, in which case we havea fake SCALAR_VALUE representing insn->imm). + * Technically we can do similar adjustments for pointers to the same object, + * but we don't support that right now. + */ +static void reg_set_min_max(struct bpf_reg_state *true_reg1, + struct bpf_reg_state *true_reg2, + struct bpf_reg_state *false_reg1, + struct bpf_reg_state *false_reg2, + u8 opcode, bool is_jmp32) { - switch (opcode) { - case BPF_JEQ: - __reg_combine_min_max(true_src, true_dst); - break; - case BPF_JNE: - __reg_combine_min_max(false_src, false_dst); - break; - } + /* If either register is a pointer, we can't learn anything about its + * variable offset from the compare (unless they were a pointer into + * the same object, but we don't bother with that). + */ + if (false_reg1->type != SCALAR_VALUE || false_reg2->type != SCALAR_VALUE) + return; + + /* fallthrough (FALSE) branch */ + regs_refine_cond_op(false_reg1, false_reg2, rev_opcode(opcode), is_jmp32); + reg_bounds_sync(false_reg1); + reg_bounds_sync(false_reg2); + + /* jump (TRUE) branch */ + regs_refine_cond_op(true_reg1, true_reg2, opcode, is_jmp32); + reg_bounds_sync(true_reg1); + reg_bounds_sync(true_reg2); } static void mark_ptr_or_null_reg(struct bpf_func_state *state, @@ -14961,22 +14929,12 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env, reg_set_min_max(&other_branch_regs[insn->dst_reg], &other_branch_regs[insn->src_reg], dst_reg, src_reg, opcode, is_jmp32); - - if (dst_reg->type == SCALAR_VALUE && - src_reg->type == SCALAR_VALUE && - !is_jmp32 && (opcode == BPF_JEQ || opcode == BPF_JNE)) { - /* Comparing for equality, we can combine knowledge */ - reg_combine_min_max(&other_branch_regs[insn->src_reg], - &other_branch_regs[insn->dst_reg], - src_reg, dst_reg, opcode); - } } else /* BPF_SRC(insn->code) == BPF_K */ { reg_set_min_max(&other_branch_regs[insn->dst_reg], src_reg /* fake one */, dst_reg, src_reg /* same fake one */, opcode, is_jmp32); } - if (BPF_SRC(insn->code) == BPF_X && src_reg->type == SCALAR_VALUE && src_reg->id && !WARN_ON_ONCE(src_reg->id != other_branch_regs[insn->src_reg].id)) { -- cgit v1.2.3 From 96381879a370425a30b810906946f64c0726450e Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sat, 11 Nov 2023 17:05:58 -0800 Subject: bpf: generalize is_scalar_branch_taken() logic Generalize is_branch_taken logic for SCALAR_VALUE register to handle cases when both registers are not constants. Previously supported vs cases are a natural subset of more generic vs set of cases. Generalized logic relies on straightforward segment intersection checks. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Acked-by: Shung-Hsi Yu Link: https://lore.kernel.org/r/20231112010609.848406-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 98 ++++++++++++++++++++++++++++++--------------------- 1 file changed, 58 insertions(+), 40 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 39ce141c55d3..f459ad99256e 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14261,82 +14261,99 @@ static int is_scalar_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_sta u8 opcode, bool is_jmp32) { struct tnum t1 = is_jmp32 ? tnum_subreg(reg1->var_off) : reg1->var_off; + struct tnum t2 = is_jmp32 ? tnum_subreg(reg2->var_off) : reg2->var_off; u64 umin1 = is_jmp32 ? (u64)reg1->u32_min_value : reg1->umin_value; u64 umax1 = is_jmp32 ? (u64)reg1->u32_max_value : reg1->umax_value; s64 smin1 = is_jmp32 ? (s64)reg1->s32_min_value : reg1->smin_value; s64 smax1 = is_jmp32 ? (s64)reg1->s32_max_value : reg1->smax_value; - u64 uval = is_jmp32 ? (u32)tnum_subreg(reg2->var_off).value : reg2->var_off.value; - s64 sval = is_jmp32 ? (s32)uval : (s64)uval; + u64 umin2 = is_jmp32 ? (u64)reg2->u32_min_value : reg2->umin_value; + u64 umax2 = is_jmp32 ? (u64)reg2->u32_max_value : reg2->umax_value; + s64 smin2 = is_jmp32 ? (s64)reg2->s32_min_value : reg2->smin_value; + s64 smax2 = is_jmp32 ? (s64)reg2->s32_max_value : reg2->smax_value; switch (opcode) { case BPF_JEQ: - if (tnum_is_const(t1)) - return !!tnum_equals_const(t1, uval); - else if (uval < umin1 || uval > umax1) + /* constants, umin/umax and smin/smax checks would be + * redundant in this case because they all should match + */ + if (tnum_is_const(t1) && tnum_is_const(t2)) + return t1.value == t2.value; + /* non-overlapping ranges */ + if (umin1 > umax2 || umax1 < umin2) return 0; - else if (sval < smin1 || sval > smax1) + if (smin1 > smax2 || smax1 < smin2) return 0; break; case BPF_JNE: - if (tnum_is_const(t1)) - return !tnum_equals_const(t1, uval); - else if (uval < umin1 || uval > umax1) + /* constants, umin/umax and smin/smax checks would be + * redundant in this case because they all should match + */ + if (tnum_is_const(t1) && tnum_is_const(t2)) + return t1.value != t2.value; + /* non-overlapping ranges */ + if (umin1 > umax2 || umax1 < umin2) return 1; - else if (sval < smin1 || sval > smax1) + if (smin1 > smax2 || smax1 < smin2) return 1; break; case BPF_JSET: - if ((~t1.mask & t1.value) & uval) + if (!is_reg_const(reg2, is_jmp32)) { + swap(reg1, reg2); + swap(t1, t2); + } + if (!is_reg_const(reg2, is_jmp32)) + return -1; + if ((~t1.mask & t1.value) & t2.value) return 1; - if (!((t1.mask | t1.value) & uval)) + if (!((t1.mask | t1.value) & t2.value)) return 0; break; case BPF_JGT: - if (umin1 > uval ) + if (umin1 > umax2) return 1; - else if (umax1 <= uval) + else if (umax1 <= umin2) return 0; break; case BPF_JSGT: - if (smin1 > sval) + if (smin1 > smax2) return 1; - else if (smax1 <= sval) + else if (smax1 <= smin2) return 0; break; case BPF_JLT: - if (umax1 < uval) + if (umax1 < umin2) return 1; - else if (umin1 >= uval) + else if (umin1 >= umax2) return 0; break; case BPF_JSLT: - if (smax1 < sval) + if (smax1 < smin2) return 1; - else if (smin1 >= sval) + else if (smin1 >= smax2) return 0; break; case BPF_JGE: - if (umin1 >= uval) + if (umin1 >= umax2) return 1; - else if (umax1 < uval) + else if (umax1 < umin2) return 0; break; case BPF_JSGE: - if (smin1 >= sval) + if (smin1 >= smax2) return 1; - else if (smax1 < sval) + else if (smax1 < smin2) return 0; break; case BPF_JLE: - if (umax1 <= uval) + if (umax1 <= umin2) return 1; - else if (umin1 > uval) + else if (umin1 > umax2) return 0; break; case BPF_JSLE: - if (smax1 <= sval) + if (smax1 <= smin2) return 1; - else if (smin1 > sval) + else if (smin1 > smax2) return 0; break; } @@ -14415,28 +14432,28 @@ static int is_pkt_ptr_branch_taken(struct bpf_reg_state *dst_reg, static int is_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, u8 opcode, bool is_jmp32) { - u64 val; - if (reg_is_pkt_pointer_any(reg1) && reg_is_pkt_pointer_any(reg2) && !is_jmp32) return is_pkt_ptr_branch_taken(reg1, reg2, opcode); - /* try to make sure reg2 is a constant SCALAR_VALUE */ - if (!is_reg_const(reg2, is_jmp32)) { - opcode = flip_opcode(opcode); - swap(reg1, reg2); - } - /* for now we expect reg2 to be a constant to make any useful decisions */ - if (!is_reg_const(reg2, is_jmp32)) - return -1; - val = reg_const_value(reg2, is_jmp32); + if (__is_pointer_value(false, reg1) || __is_pointer_value(false, reg2)) { + u64 val; + + /* arrange that reg2 is a scalar, and reg1 is a pointer */ + if (!is_reg_const(reg2, is_jmp32)) { + opcode = flip_opcode(opcode); + swap(reg1, reg2); + } + /* and ensure that reg2 is a constant */ + if (!is_reg_const(reg2, is_jmp32)) + return -1; - if (__is_pointer_value(false, reg1)) { if (!reg_not_null(reg1)) return -1; /* If pointer is valid tests against zero will fail so we can * use this to direct branch taken. */ + val = reg_const_value(reg2, is_jmp32); if (val != 0) return -1; @@ -14450,6 +14467,7 @@ static int is_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg } } + /* now deal with two scalars, but not necessarily constants */ return is_scalar_branch_taken(reg1, reg2, opcode, is_jmp32); } -- cgit v1.2.3 From be41a203bb9e0159099e189e510388fe61962eb8 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sat, 11 Nov 2023 17:05:59 -0800 Subject: bpf: enhance BPF_JEQ/BPF_JNE is_branch_taken logic Use 32-bit subranges to prune some 64-bit BPF_JEQ/BPF_JNE conditions that otherwise would be "inconclusive" (i.e., is_branch_taken() would return -1). This can happen, for example, when registers are initialized as 64-bit u64/s64, then compared for inequality as 32-bit subregisters, and then followed by 64-bit equality/inequality check. That 32-bit inequality can establish some pattern for lower 32 bits of a register (e.g., s< 0 condition determines whether the bit #31 is zero or not), while overall 64-bit value could be anything (according to a value range representation). This is not a fancy quirky special case, but actually a handling that's necessary to prevent correctness issue with BPF verifier's range tracking: set_range_min_max() assumes that register ranges are non-overlapping, and if that condition is not guaranteed by is_branch_taken() we can end up with invalid ranges, where min > max. [0] https://lore.kernel.org/bpf/CACkBjsY2q1_fUohD7hRmKGqv1MV=eP2f6XK8kjkYNw7BaiF8iQ@mail.gmail.com/ Acked-by: Shung-Hsi Yu Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231112010609.848406-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f459ad99256e..65570eedfe88 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14283,6 +14283,18 @@ static int is_scalar_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_sta return 0; if (smin1 > smax2 || smax1 < smin2) return 0; + if (!is_jmp32) { + /* if 64-bit ranges are inconclusive, see if we can + * utilize 32-bit subrange knowledge to eliminate + * branches that can't be taken a priori + */ + if (reg1->u32_min_value > reg2->u32_max_value || + reg1->u32_max_value < reg2->u32_min_value) + return 0; + if (reg1->s32_min_value > reg2->s32_max_value || + reg1->s32_max_value < reg2->s32_min_value) + return 0; + } break; case BPF_JNE: /* constants, umin/umax and smin/smax checks would be @@ -14295,6 +14307,18 @@ static int is_scalar_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_sta return 1; if (smin1 > smax2 || smax1 < smin2) return 1; + if (!is_jmp32) { + /* if 64-bit ranges are inconclusive, see if we can + * utilize 32-bit subrange knowledge to eliminate + * branches that can't be taken a priori + */ + if (reg1->u32_min_value > reg2->u32_max_value || + reg1->u32_max_value < reg2->u32_min_value) + return 1; + if (reg1->s32_min_value > reg2->s32_max_value || + reg1->s32_max_value < reg2->s32_min_value) + return 1; + } break; case BPF_JSET: if (!is_reg_const(reg2, is_jmp32)) { -- cgit v1.2.3 From 5f99f312bd3bedb3b266b0d26376a8c500cdc97f Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sat, 11 Nov 2023 17:06:00 -0800 Subject: bpf: add register bounds sanity checks and sanitization Add simple sanity checks that validate well-formed ranges (min <= max) across u64, s64, u32, and s32 ranges. Also for cases when the value is constant (either 64-bit or 32-bit), we validate that ranges and tnums are in agreement. These bounds checks are performed at the end of BPF_ALU/BPF_ALU64 operations, on conditional jumps, and for LDX instructions (where subreg zero/sign extension is probably the most important to check). This covers most of the interesting cases. Also, we validate the sanity of the return register when manually adjusting it for some special helpers. By default, sanity violation will trigger a warning in verifier log and resetting register bounds to "unbounded" ones. But to aid development and debugging, BPF_F_TEST_SANITY_STRICT flag is added, which will trigger hard failure of verification with -EFAULT on register bounds violations. This allows selftests to catch such issues. veristat will also gain a CLI option to enable this behavior. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Acked-by: Shung-Hsi Yu Link: https://lore.kernel.org/r/20231112010609.848406-5-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf_verifier.h | 1 + include/uapi/linux/bpf.h | 3 ++ kernel/bpf/syscall.c | 3 +- kernel/bpf/verifier.c | 117 ++++++++++++++++++++++++++++++++--------- tools/include/uapi/linux/bpf.h | 3 ++ 5 files changed, 101 insertions(+), 26 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 24213a99cc79..402b6bc44a1b 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -602,6 +602,7 @@ struct bpf_verifier_env { int stack_size; /* number of states to be processed */ bool strict_alignment; /* perform strict pointer alignment checks */ bool test_state_freq; /* test verifier with different pruning frequency */ + bool test_sanity_strict; /* fail verification on sanity violations */ struct bpf_verifier_state *cur_state; /* current verifier state */ struct bpf_verifier_state_list **explored_states; /* search pruning optimization */ struct bpf_verifier_state_list *free_list; diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 7cf8bcf9f6a2..8a5855fcee69 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1200,6 +1200,9 @@ enum bpf_perf_event_type { */ #define BPF_F_XDP_DEV_BOUND_ONLY (1U << 6) +/* The verifier internal test flag. Behavior is undefined */ +#define BPF_F_TEST_SANITY_STRICT (1U << 7) + /* link_create.kprobe_multi.flags used in LINK_CREATE command for * BPF_TRACE_KPROBE_MULTI attach type to create return probe. */ diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 0ed286b8a0f0..f266e03ba342 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2573,7 +2573,8 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) BPF_F_SLEEPABLE | BPF_F_TEST_RND_HI32 | BPF_F_XDP_HAS_FRAGS | - BPF_F_XDP_DEV_BOUND_ONLY)) + BPF_F_XDP_DEV_BOUND_ONLY | + BPF_F_TEST_SANITY_STRICT)) return -EINVAL; if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 65570eedfe88..e7edacf86e0f 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2615,6 +2615,56 @@ static void reg_bounds_sync(struct bpf_reg_state *reg) __update_reg_bounds(reg); } +static int reg_bounds_sanity_check(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, const char *ctx) +{ + const char *msg; + + if (reg->umin_value > reg->umax_value || + reg->smin_value > reg->smax_value || + reg->u32_min_value > reg->u32_max_value || + reg->s32_min_value > reg->s32_max_value) { + msg = "range bounds violation"; + goto out; + } + + if (tnum_is_const(reg->var_off)) { + u64 uval = reg->var_off.value; + s64 sval = (s64)uval; + + if (reg->umin_value != uval || reg->umax_value != uval || + reg->smin_value != sval || reg->smax_value != sval) { + msg = "const tnum out of sync with range bounds"; + goto out; + } + } + + if (tnum_subreg_is_const(reg->var_off)) { + u32 uval32 = tnum_subreg(reg->var_off).value; + s32 sval32 = (s32)uval32; + + if (reg->u32_min_value != uval32 || reg->u32_max_value != uval32 || + reg->s32_min_value != sval32 || reg->s32_max_value != sval32) { + msg = "const subreg tnum out of sync with range bounds"; + goto out; + } + } + + return 0; +out: + verbose(env, "REG SANITY VIOLATION (%s): %s u64=[%#llx, %#llx] " + "s64=[%#llx, %#llx] u32=[%#x, %#x] s32=[%#x, %#x] var_off=(%#llx, %#llx)\n", + ctx, msg, reg->umin_value, reg->umax_value, + reg->smin_value, reg->smax_value, + reg->u32_min_value, reg->u32_max_value, + reg->s32_min_value, reg->s32_max_value, + reg->var_off.value, reg->var_off.mask); + if (env->test_sanity_strict) + return -EFAULT; + __mark_reg_unbounded(reg); + return 0; +} + static bool __reg32_bound_s64(s32 a) { return a >= 0 && a <= S32_MAX; @@ -9982,14 +10032,15 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) return 0; } -static void do_refine_retval_range(struct bpf_reg_state *regs, int ret_type, - int func_id, - struct bpf_call_arg_meta *meta) +static int do_refine_retval_range(struct bpf_verifier_env *env, + struct bpf_reg_state *regs, int ret_type, + int func_id, + struct bpf_call_arg_meta *meta) { struct bpf_reg_state *ret_reg = ®s[BPF_REG_0]; if (ret_type != RET_INTEGER) - return; + return 0; switch (func_id) { case BPF_FUNC_get_stack: @@ -10015,6 +10066,8 @@ static void do_refine_retval_range(struct bpf_reg_state *regs, int ret_type, reg_bounds_sync(ret_reg); break; } + + return reg_bounds_sanity_check(env, ret_reg, "retval"); } static int @@ -10666,7 +10719,9 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn regs[BPF_REG_0].ref_obj_id = id; } - do_refine_retval_range(regs, fn->ret_type, func_id, &meta); + err = do_refine_retval_range(env, regs, fn->ret_type, func_id, &meta); + if (err) + return err; err = check_map_func_compatibility(env, meta.map_ptr, func_id); if (err) @@ -14166,13 +14221,12 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) /* check dest operand */ err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK); + err = err ?: adjust_reg_min_max_vals(env, insn); if (err) return err; - - return adjust_reg_min_max_vals(env, insn); } - return 0; + return reg_bounds_sanity_check(env, ®s[insn->dst_reg], "alu"); } static void find_good_pkt_pointers(struct bpf_verifier_state *vstate, @@ -14653,18 +14707,21 @@ again: * Technically we can do similar adjustments for pointers to the same object, * but we don't support that right now. */ -static void reg_set_min_max(struct bpf_reg_state *true_reg1, - struct bpf_reg_state *true_reg2, - struct bpf_reg_state *false_reg1, - struct bpf_reg_state *false_reg2, - u8 opcode, bool is_jmp32) +static int reg_set_min_max(struct bpf_verifier_env *env, + struct bpf_reg_state *true_reg1, + struct bpf_reg_state *true_reg2, + struct bpf_reg_state *false_reg1, + struct bpf_reg_state *false_reg2, + u8 opcode, bool is_jmp32) { + int err; + /* If either register is a pointer, we can't learn anything about its * variable offset from the compare (unless they were a pointer into * the same object, but we don't bother with that). */ if (false_reg1->type != SCALAR_VALUE || false_reg2->type != SCALAR_VALUE) - return; + return 0; /* fallthrough (FALSE) branch */ regs_refine_cond_op(false_reg1, false_reg2, rev_opcode(opcode), is_jmp32); @@ -14675,6 +14732,12 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg1, regs_refine_cond_op(true_reg1, true_reg2, opcode, is_jmp32); reg_bounds_sync(true_reg1); reg_bounds_sync(true_reg2); + + err = reg_bounds_sanity_check(env, true_reg1, "true_reg1"); + err = err ?: reg_bounds_sanity_check(env, true_reg2, "true_reg2"); + err = err ?: reg_bounds_sanity_check(env, false_reg1, "false_reg1"); + err = err ?: reg_bounds_sanity_check(env, false_reg2, "false_reg2"); + return err; } static void mark_ptr_or_null_reg(struct bpf_func_state *state, @@ -14968,15 +15031,20 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env, other_branch_regs = other_branch->frame[other_branch->curframe]->regs; if (BPF_SRC(insn->code) == BPF_X) { - reg_set_min_max(&other_branch_regs[insn->dst_reg], - &other_branch_regs[insn->src_reg], - dst_reg, src_reg, opcode, is_jmp32); + err = reg_set_min_max(env, + &other_branch_regs[insn->dst_reg], + &other_branch_regs[insn->src_reg], + dst_reg, src_reg, opcode, is_jmp32); } else /* BPF_SRC(insn->code) == BPF_K */ { - reg_set_min_max(&other_branch_regs[insn->dst_reg], - src_reg /* fake one */, - dst_reg, src_reg /* same fake one */, - opcode, is_jmp32); + err = reg_set_min_max(env, + &other_branch_regs[insn->dst_reg], + src_reg /* fake one */, + dst_reg, src_reg /* same fake one */, + opcode, is_jmp32); } + if (err) + return err; + if (BPF_SRC(insn->code) == BPF_X && src_reg->type == SCALAR_VALUE && src_reg->id && !WARN_ON_ONCE(src_reg->id != other_branch_regs[insn->src_reg].id)) { @@ -17479,10 +17547,8 @@ static int do_check(struct bpf_verifier_env *env) insn->off, BPF_SIZE(insn->code), BPF_READ, insn->dst_reg, false, BPF_MODE(insn->code) == BPF_MEMSX); - if (err) - return err; - - err = save_aux_ptr_type(env, src_reg_type, true); + err = err ?: save_aux_ptr_type(env, src_reg_type, true); + err = err ?: reg_bounds_sanity_check(env, ®s[insn->dst_reg], "ldx"); if (err) return err; } else if (class == BPF_STX) { @@ -20769,6 +20835,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u3 if (is_priv) env->test_state_freq = attr->prog_flags & BPF_F_TEST_STATE_FREQ; + env->test_sanity_strict = attr->prog_flags & BPF_F_TEST_SANITY_STRICT; env->explored_states = kvcalloc(state_htab_size(env), sizeof(struct bpf_verifier_state_list *), diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 7cf8bcf9f6a2..8a5855fcee69 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -1200,6 +1200,9 @@ enum bpf_perf_event_type { */ #define BPF_F_XDP_DEV_BOUND_ONLY (1U << 6) +/* The verifier internal test flag. Behavior is undefined */ +#define BPF_F_TEST_SANITY_STRICT (1U << 7) + /* link_create.kprobe_multi.flags used in LINK_CREATE command for * BPF_TRACE_KPROBE_MULTI attach type to create return probe. */ -- cgit v1.2.3 From 3cf98cf594ea923b8b1e0385b580d3d8aae68c06 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sat, 11 Nov 2023 17:06:01 -0800 Subject: bpf: remove redundant s{32,64} -> u{32,64} deduction logic Equivalent checks were recently added in more succinct and, arguably, safer form in: - f188765f23a5 ("bpf: derive smin32/smax32 from umin32/umax32 bounds"); - 2e74aef782d3 ("bpf: derive smin/smax from umin/max bounds"). The checks we are removing in this patch set do similar checks to detect if entire u32/u64 range has signed bit set or not set, but does it with two separate checks. Further, we forcefully overwrite either smin or smax (and 32-bit equvalents) without applying normal min/max intersection logic. It's not clear why that would be correct in all cases and seems to work by accident. This logic is also "gated" by previous signed -> unsigned derivation, which returns early. All this is quite confusing and seems error-prone, while we already have at least equivalent checks happening earlier. So remove this duplicate and error-prone logic to simplify things a bit. Acked-by: Shung-Hsi Yu Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231112010609.848406-6-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 36 ------------------------------------ 1 file changed, 36 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index e7edacf86e0f..53a9e3e79ab4 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2411,24 +2411,6 @@ static void __reg32_deduce_bounds(struct bpf_reg_state *reg) min_t(u32, reg->s32_max_value, reg->u32_max_value); return; } - /* Learn sign from unsigned bounds. Signed bounds cross the sign - * boundary, so we must be careful. - */ - if ((s32)reg->u32_max_value >= 0) { - /* Positive. We can't learn anything from the smin, but smax - * is positive, hence safe. - */ - reg->s32_min_value = reg->u32_min_value; - reg->s32_max_value = reg->u32_max_value = - min_t(u32, reg->s32_max_value, reg->u32_max_value); - } else if ((s32)reg->u32_min_value < 0) { - /* Negative. We can't learn anything from the smax, but smin - * is negative, hence safe. - */ - reg->s32_min_value = reg->u32_min_value = - max_t(u32, reg->s32_min_value, reg->u32_min_value); - reg->s32_max_value = reg->u32_max_value; - } } static void __reg64_deduce_bounds(struct bpf_reg_state *reg) @@ -2516,24 +2498,6 @@ static void __reg64_deduce_bounds(struct bpf_reg_state *reg) reg->umax_value); return; } - /* Learn sign from unsigned bounds. Signed bounds cross the sign - * boundary, so we must be careful. - */ - if ((s64)reg->umax_value >= 0) { - /* Positive. We can't learn anything from the smin, but smax - * is positive, hence safe. - */ - reg->smin_value = reg->umin_value; - reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value, - reg->umax_value); - } else if ((s64)reg->umin_value < 0) { - /* Negative. We can't learn anything from the smax, but smin - * is negative, hence safe. - */ - reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value, - reg->umin_value); - reg->smax_value = reg->umax_value; - } } static void __reg_deduce_mixed_bounds(struct bpf_reg_state *reg) -- cgit v1.2.3 From cf5fe3c71c5a34ac0108afc550407c672d0a032d Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sat, 11 Nov 2023 17:06:02 -0800 Subject: bpf: make __reg{32,64}_deduce_bounds logic more robust This change doesn't seem to have any effect on selftests and production BPF object files, but we preemptively try to make it more robust. First, "learn sign from signed bounds" comment is misleading, as we are learning not just sign, but also values. Second, we simplify the check for determining whether entire range is positive or negative similarly to other checks added earlier, using appropriate u32/u64 cast and single comparisons. As explain in comments in __reg64_deduce_bounds(), the checks are equivalent. Last but not least, smin/smax and s32_min/s32_max reassignment based on min/max of both umin/umax and smin/smax (and 32-bit equivalents) is hard to explain and justify. We are updating unsigned bounds from signed bounds, why would we update signed bounds at the same time? This might be correct, but it's far from obvious why and the code or comments don't try to justify this. Given we've added a separate deduction of signed bounds from unsigned bounds earlier, this seems at least redundant, if not just wrong. In short, we remove doubtful pieces, and streamline the rest to follow the logic and approach of the rest of reg_bounds_sync() checks. Acked-by: Shung-Hsi Yu Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231112010609.848406-7-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 24 ++++++++---------------- 1 file changed, 8 insertions(+), 16 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 53a9e3e79ab4..59505881e7a7 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2399,17 +2399,13 @@ static void __reg32_deduce_bounds(struct bpf_reg_state *reg) reg->s32_min_value = max_t(s32, reg->s32_min_value, reg->u32_min_value); reg->s32_max_value = min_t(s32, reg->s32_max_value, reg->u32_max_value); } - /* Learn sign from signed bounds. - * If we cannot cross the sign boundary, then signed and unsigned bounds + /* If we cannot cross the sign boundary, then signed and unsigned bounds * are the same, so combine. This works even in the negative case, e.g. * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff. */ - if (reg->s32_min_value >= 0 || reg->s32_max_value < 0) { - reg->s32_min_value = reg->u32_min_value = - max_t(u32, reg->s32_min_value, reg->u32_min_value); - reg->s32_max_value = reg->u32_max_value = - min_t(u32, reg->s32_max_value, reg->u32_max_value); - return; + if ((u32)reg->s32_min_value <= (u32)reg->s32_max_value) { + reg->u32_min_value = max_t(u32, reg->s32_min_value, reg->u32_min_value); + reg->u32_max_value = min_t(u32, reg->s32_max_value, reg->u32_max_value); } } @@ -2486,17 +2482,13 @@ static void __reg64_deduce_bounds(struct bpf_reg_state *reg) reg->smin_value = max_t(s64, reg->smin_value, reg->umin_value); reg->smax_value = min_t(s64, reg->smax_value, reg->umax_value); } - /* Learn sign from signed bounds. - * If we cannot cross the sign boundary, then signed and unsigned bounds + /* If we cannot cross the sign boundary, then signed and unsigned bounds * are the same, so combine. This works even in the negative case, e.g. * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff. */ - if (reg->smin_value >= 0 || reg->smax_value < 0) { - reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value, - reg->umin_value); - reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value, - reg->umax_value); - return; + if ((u64)reg->smin_value <= (u64)reg->smax_value) { + reg->umin_value = max_t(u64, reg->smin_value, reg->umin_value); + reg->umax_value = min_t(u64, reg->smax_value, reg->umax_value); } } -- cgit v1.2.3 From ff8867af01daa7ea770bebf5f91199b7434b74e5 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Fri, 17 Nov 2023 09:14:04 -0800 Subject: bpf: rename BPF_F_TEST_SANITY_STRICT to BPF_F_TEST_REG_INVARIANTS Rename verifier internal flag BPF_F_TEST_SANITY_STRICT to more neutral BPF_F_TEST_REG_INVARIANTS. This is a follow up to [0]. A few selftests and veristat need to be adjusted in the same patch as well. [0] https://patchwork.kernel.org/project/netdevbpf/patch/20231112010609.848406-5-andrii@kernel.org/ Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231117171404.225508-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf_verifier.h | 2 +- include/uapi/linux/bpf.h | 2 +- kernel/bpf/syscall.c | 2 +- kernel/bpf/verifier.c | 6 +++--- tools/include/uapi/linux/bpf.h | 2 +- tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c | 2 +- tools/testing/selftests/bpf/prog_tests/reg_bounds.c | 2 +- tools/testing/selftests/bpf/progs/verifier_bounds.c | 4 ++-- tools/testing/selftests/bpf/test_loader.c | 6 +++--- tools/testing/selftests/bpf/test_sock_addr.c | 3 +-- tools/testing/selftests/bpf/test_verifier.c | 2 +- tools/testing/selftests/bpf/testing_helpers.c | 4 ++-- tools/testing/selftests/bpf/veristat.c | 12 ++++++------ 13 files changed, 24 insertions(+), 25 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 402b6bc44a1b..52a4012b8255 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -602,7 +602,7 @@ struct bpf_verifier_env { int stack_size; /* number of states to be processed */ bool strict_alignment; /* perform strict pointer alignment checks */ bool test_state_freq; /* test verifier with different pruning frequency */ - bool test_sanity_strict; /* fail verification on sanity violations */ + bool test_reg_invariants; /* fail verification on register invariants violations */ struct bpf_verifier_state *cur_state; /* current verifier state */ struct bpf_verifier_state_list **explored_states; /* search pruning optimization */ struct bpf_verifier_state_list *free_list; diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 8a5855fcee69..7a5498242eaa 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1201,7 +1201,7 @@ enum bpf_perf_event_type { #define BPF_F_XDP_DEV_BOUND_ONLY (1U << 6) /* The verifier internal test flag. Behavior is undefined */ -#define BPF_F_TEST_SANITY_STRICT (1U << 7) +#define BPF_F_TEST_REG_INVARIANTS (1U << 7) /* link_create.kprobe_multi.flags used in LINK_CREATE command for * BPF_TRACE_KPROBE_MULTI attach type to create return probe. diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index f266e03ba342..5e43ddd1b83f 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2574,7 +2574,7 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) BPF_F_TEST_RND_HI32 | BPF_F_XDP_HAS_FRAGS | BPF_F_XDP_DEV_BOUND_ONLY | - BPF_F_TEST_SANITY_STRICT)) + BPF_F_TEST_REG_INVARIANTS)) return -EINVAL; if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 59505881e7a7..7c3461b89513 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2608,14 +2608,14 @@ static int reg_bounds_sanity_check(struct bpf_verifier_env *env, return 0; out: - verbose(env, "REG SANITY VIOLATION (%s): %s u64=[%#llx, %#llx] " + verbose(env, "REG INVARIANTS VIOLATION (%s): %s u64=[%#llx, %#llx] " "s64=[%#llx, %#llx] u32=[%#x, %#x] s32=[%#x, %#x] var_off=(%#llx, %#llx)\n", ctx, msg, reg->umin_value, reg->umax_value, reg->smin_value, reg->smax_value, reg->u32_min_value, reg->u32_max_value, reg->s32_min_value, reg->s32_max_value, reg->var_off.value, reg->var_off.mask); - if (env->test_sanity_strict) + if (env->test_reg_invariants) return -EFAULT; __mark_reg_unbounded(reg); return 0; @@ -20791,7 +20791,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u3 if (is_priv) env->test_state_freq = attr->prog_flags & BPF_F_TEST_STATE_FREQ; - env->test_sanity_strict = attr->prog_flags & BPF_F_TEST_SANITY_STRICT; + env->test_reg_invariants = attr->prog_flags & BPF_F_TEST_REG_INVARIANTS; env->explored_states = kvcalloc(state_htab_size(env), sizeof(struct bpf_verifier_state_list *), diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 8a5855fcee69..7a5498242eaa 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -1201,7 +1201,7 @@ enum bpf_perf_event_type { #define BPF_F_XDP_DEV_BOUND_ONLY (1U << 6) /* The verifier internal test flag. Behavior is undefined */ -#define BPF_F_TEST_SANITY_STRICT (1U << 7) +#define BPF_F_TEST_REG_INVARIANTS (1U << 7) /* link_create.kprobe_multi.flags used in LINK_CREATE command for * BPF_TRACE_KPROBE_MULTI attach type to create return probe. diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c b/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c index 3f2d70831873..e770912fc1d2 100644 --- a/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c +++ b/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c @@ -35,7 +35,7 @@ static int check_load(const char *file, enum bpf_prog_type type) } bpf_program__set_type(prog, type); - bpf_program__set_flags(prog, BPF_F_TEST_RND_HI32 | BPF_F_TEST_SANITY_STRICT); + bpf_program__set_flags(prog, BPF_F_TEST_RND_HI32 | BPF_F_TEST_REG_INVARIANTS); bpf_program__set_log_level(prog, 4 | extra_prog_load_log_flags); err = bpf_object__load(obj); diff --git a/tools/testing/selftests/bpf/prog_tests/reg_bounds.c b/tools/testing/selftests/bpf/prog_tests/reg_bounds.c index fe0cb906644b..7a8b0bf0a7f8 100644 --- a/tools/testing/selftests/bpf/prog_tests/reg_bounds.c +++ b/tools/testing/selftests/bpf/prog_tests/reg_bounds.c @@ -838,7 +838,7 @@ static int load_range_cmp_prog(struct range x, struct range y, enum op op, .log_level = 2, .log_buf = log_buf, .log_size = log_sz, - .prog_flags = BPF_F_TEST_SANITY_STRICT, + .prog_flags = BPF_F_TEST_REG_INVARIANTS, ); /* ; skip exit block below diff --git a/tools/testing/selftests/bpf/progs/verifier_bounds.c b/tools/testing/selftests/bpf/progs/verifier_bounds.c index 0c1460936373..ec430b71730b 100644 --- a/tools/testing/selftests/bpf/progs/verifier_bounds.c +++ b/tools/testing/selftests/bpf/progs/verifier_bounds.c @@ -965,7 +965,7 @@ l0_%=: r0 = 0; \ SEC("xdp") __description("bound check with JMP_JSLT for crossing 64-bit signed boundary") __success __retval(0) -__flag(!BPF_F_TEST_SANITY_STRICT) /* known sanity violation */ +__flag(!BPF_F_TEST_REG_INVARIANTS) /* known invariants violation */ __naked void crossing_64_bit_signed_boundary_2(void) { asm volatile (" \ @@ -1047,7 +1047,7 @@ l0_%=: r0 = 0; \ SEC("xdp") __description("bound check with JMP32_JSLT for crossing 32-bit signed boundary") __success __retval(0) -__flag(!BPF_F_TEST_SANITY_STRICT) /* known sanity violation */ +__flag(!BPF_F_TEST_REG_INVARIANTS) /* known invariants violation */ __naked void crossing_32_bit_signed_boundary_2(void) { asm volatile (" \ diff --git a/tools/testing/selftests/bpf/test_loader.c b/tools/testing/selftests/bpf/test_loader.c index 57e27b1a73a6..a350ecdfba4a 100644 --- a/tools/testing/selftests/bpf/test_loader.c +++ b/tools/testing/selftests/bpf/test_loader.c @@ -179,7 +179,7 @@ static int parse_test_spec(struct test_loader *tester, memset(spec, 0, sizeof(*spec)); spec->prog_name = bpf_program__name(prog); - spec->prog_flags = BPF_F_TEST_SANITY_STRICT; /* by default be strict */ + spec->prog_flags = BPF_F_TEST_REG_INVARIANTS; /* by default be strict */ btf = bpf_object__btf(obj); if (!btf) { @@ -280,8 +280,8 @@ static int parse_test_spec(struct test_loader *tester, update_flags(&spec->prog_flags, BPF_F_SLEEPABLE, clear); } else if (strcmp(val, "BPF_F_XDP_HAS_FRAGS") == 0) { update_flags(&spec->prog_flags, BPF_F_XDP_HAS_FRAGS, clear); - } else if (strcmp(val, "BPF_F_TEST_SANITY_STRICT") == 0) { - update_flags(&spec->prog_flags, BPF_F_TEST_SANITY_STRICT, clear); + } else if (strcmp(val, "BPF_F_TEST_REG_INVARIANTS") == 0) { + update_flags(&spec->prog_flags, BPF_F_TEST_REG_INVARIANTS, clear); } else /* assume numeric value */ { err = parse_int(val, &flags, "test prog flags"); if (err) diff --git a/tools/testing/selftests/bpf/test_sock_addr.c b/tools/testing/selftests/bpf/test_sock_addr.c index 878c077e0fa7..b0068a9d2cfe 100644 --- a/tools/testing/selftests/bpf/test_sock_addr.c +++ b/tools/testing/selftests/bpf/test_sock_addr.c @@ -679,8 +679,7 @@ static int load_path(const struct sock_addr_test *test, const char *path) bpf_program__set_type(prog, BPF_PROG_TYPE_CGROUP_SOCK_ADDR); bpf_program__set_expected_attach_type(prog, test->expected_attach_type); - bpf_program__set_flags(prog, BPF_F_TEST_RND_HI32); - bpf_program__set_flags(prog, BPF_F_TEST_SANITY_STRICT); + bpf_program__set_flags(prog, BPF_F_TEST_RND_HI32 | BPF_F_TEST_REG_INVARIANTS); err = bpf_object__load(obj); if (err) { diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index 4992022f3137..f36e41435be7 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -1588,7 +1588,7 @@ static void do_test_single(struct bpf_test *test, bool unpriv, if (fixup_skips != skips) return; - pflags = BPF_F_TEST_RND_HI32 | BPF_F_TEST_SANITY_STRICT; + pflags = BPF_F_TEST_RND_HI32 | BPF_F_TEST_REG_INVARIANTS; if (test->flags & F_LOAD_WITH_STRICT_ALIGNMENT) pflags |= BPF_F_STRICT_ALIGNMENT; if (test->flags & F_NEEDS_EFFICIENT_UNALIGNED_ACCESS) diff --git a/tools/testing/selftests/bpf/testing_helpers.c b/tools/testing/selftests/bpf/testing_helpers.c index 9786a94a666c..d2458c1b1671 100644 --- a/tools/testing/selftests/bpf/testing_helpers.c +++ b/tools/testing/selftests/bpf/testing_helpers.c @@ -276,7 +276,7 @@ int bpf_prog_test_load(const char *file, enum bpf_prog_type type, if (type != BPF_PROG_TYPE_UNSPEC && bpf_program__type(prog) != type) bpf_program__set_type(prog, type); - flags = bpf_program__flags(prog) | BPF_F_TEST_RND_HI32 | BPF_F_TEST_SANITY_STRICT; + flags = bpf_program__flags(prog) | BPF_F_TEST_RND_HI32 | BPF_F_TEST_REG_INVARIANTS; bpf_program__set_flags(prog, flags); err = bpf_object__load(obj); @@ -299,7 +299,7 @@ int bpf_test_load_program(enum bpf_prog_type type, const struct bpf_insn *insns, { LIBBPF_OPTS(bpf_prog_load_opts, opts, .kern_version = kern_version, - .prog_flags = BPF_F_TEST_RND_HI32 | BPF_F_TEST_SANITY_STRICT, + .prog_flags = BPF_F_TEST_RND_HI32 | BPF_F_TEST_REG_INVARIANTS, .log_level = extra_prog_load_log_flags, .log_buf = log_buf, .log_size = log_buf_sz, diff --git a/tools/testing/selftests/bpf/veristat.c b/tools/testing/selftests/bpf/veristat.c index 609fd9753af0..1d418d66e375 100644 --- a/tools/testing/selftests/bpf/veristat.c +++ b/tools/testing/selftests/bpf/veristat.c @@ -145,7 +145,7 @@ static struct env { bool debug; bool quiet; bool force_checkpoints; - bool strict_range_sanity; + bool force_reg_invariants; enum resfmt out_fmt; bool show_version; bool comparison_mode; @@ -225,8 +225,8 @@ static const struct argp_option opts[] = { { "filter", 'f', "FILTER", 0, "Filter expressions (or @filename for file with expressions)." }, { "test-states", 't', NULL, 0, "Force frequent BPF verifier state checkpointing (set BPF_F_TEST_STATE_FREQ program flag)" }, - { "test-sanity", 'r', NULL, 0, - "Force strict BPF verifier register sanity behavior (BPF_F_TEST_SANITY_STRICT program flag)" }, + { "test-reg-invariants", 'r', NULL, 0, + "Force BPF verifier failure on register invariant violation (BPF_F_TEST_REG_INVARIANTS program flag)" }, {}, }; @@ -299,7 +299,7 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state) env.force_checkpoints = true; break; case 'r': - env.strict_range_sanity = true; + env.force_reg_invariants = true; break; case 'n': errno = 0; @@ -1028,8 +1028,8 @@ static int process_prog(const char *filename, struct bpf_object *obj, struct bpf if (env.force_checkpoints) bpf_program__set_flags(prog, bpf_program__flags(prog) | BPF_F_TEST_STATE_FREQ); - if (env.strict_range_sanity) - bpf_program__set_flags(prog, bpf_program__flags(prog) | BPF_F_TEST_SANITY_STRICT); + if (env.force_reg_invariants) + bpf_program__set_flags(prog, bpf_program__flags(prog) | BPF_F_TEST_REG_INVARIANTS); err = bpf_object__load(obj); env.progs_processed++; -- cgit v1.2.3 From db840d389bad60ce6f3aadc1079da13e7e993a16 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Fri, 17 Nov 2023 19:46:16 -0800 Subject: bpf: move verbose_linfo() into kernel/bpf/log.c verifier.c is huge. Let's try to move out parts that are logging-related into log.c, as we previously did with bpf_log() and other related stuff. This patch moves line info verbose output routines: it's pretty self-contained and isolated code, so there is no problem with this. Acked-by: Eduard Zingerman Acked-by: Stanislav Fomichev Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231118034623.3320920-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf_verifier.h | 4 +++ kernel/bpf/log.c | 59 ++++++++++++++++++++++++++++++++++++++++++++ kernel/bpf/verifier.c | 57 ------------------------------------------ 3 files changed, 63 insertions(+), 57 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 52a4012b8255..d896f3db6a22 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -680,6 +680,10 @@ int bpf_vlog_init(struct bpf_verifier_log *log, u32 log_level, void bpf_vlog_reset(struct bpf_verifier_log *log, u64 new_pos); int bpf_vlog_finalize(struct bpf_verifier_log *log, u32 *log_size_actual); +__printf(3, 4) void verbose_linfo(struct bpf_verifier_env *env, + u32 insn_off, + const char *prefix_fmt, ...); + static inline struct bpf_func_state *cur_func(struct bpf_verifier_env *env) { struct bpf_verifier_state *cur = env->cur_state; diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c index 850494423530..f20e1449c882 100644 --- a/kernel/bpf/log.c +++ b/kernel/bpf/log.c @@ -10,6 +10,8 @@ #include #include +#define verbose(env, fmt, args...) bpf_verifier_log_write(env, fmt, ##args) + static bool bpf_verifier_log_attr_valid(const struct bpf_verifier_log *log) { /* ubuf and len_total should both be specified (or not) together */ @@ -325,3 +327,60 @@ __printf(2, 3) void bpf_log(struct bpf_verifier_log *log, va_end(args); } EXPORT_SYMBOL_GPL(bpf_log); + +static const struct bpf_line_info * +find_linfo(const struct bpf_verifier_env *env, u32 insn_off) +{ + const struct bpf_line_info *linfo; + const struct bpf_prog *prog; + u32 i, nr_linfo; + + prog = env->prog; + nr_linfo = prog->aux->nr_linfo; + + if (!nr_linfo || insn_off >= prog->len) + return NULL; + + linfo = prog->aux->linfo; + for (i = 1; i < nr_linfo; i++) + if (insn_off < linfo[i].insn_off) + break; + + return &linfo[i - 1]; +} + +static const char *ltrim(const char *s) +{ + while (isspace(*s)) + s++; + + return s; +} + +__printf(3, 4) void verbose_linfo(struct bpf_verifier_env *env, + u32 insn_off, + const char *prefix_fmt, ...) +{ + const struct bpf_line_info *linfo; + + if (!bpf_verifier_log_needed(&env->log)) + return; + + linfo = find_linfo(env, insn_off); + if (!linfo || linfo == env->prev_linfo) + return; + + if (prefix_fmt) { + va_list args; + + va_start(args, prefix_fmt); + bpf_verifier_vlog(&env->log, prefix_fmt, args); + va_end(args); + } + + verbose(env, "%s\n", + ltrim(btf_name_by_offset(env->prog->aux->btf, + linfo->line_off))); + + env->prev_linfo = linfo; +} diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 7c3461b89513..683fdda25c13 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -337,27 +337,6 @@ struct btf *btf_vmlinux; static DEFINE_MUTEX(bpf_verifier_lock); -static const struct bpf_line_info * -find_linfo(const struct bpf_verifier_env *env, u32 insn_off) -{ - const struct bpf_line_info *linfo; - const struct bpf_prog *prog; - u32 i, nr_linfo; - - prog = env->prog; - nr_linfo = prog->aux->nr_linfo; - - if (!nr_linfo || insn_off >= prog->len) - return NULL; - - linfo = prog->aux->linfo; - for (i = 1; i < nr_linfo; i++) - if (insn_off < linfo[i].insn_off) - break; - - return &linfo[i - 1]; -} - __printf(2, 3) static void verbose(void *private_data, const char *fmt, ...) { struct bpf_verifier_env *env = private_data; @@ -371,42 +350,6 @@ __printf(2, 3) static void verbose(void *private_data, const char *fmt, ...) va_end(args); } -static const char *ltrim(const char *s) -{ - while (isspace(*s)) - s++; - - return s; -} - -__printf(3, 4) static void verbose_linfo(struct bpf_verifier_env *env, - u32 insn_off, - const char *prefix_fmt, ...) -{ - const struct bpf_line_info *linfo; - - if (!bpf_verifier_log_needed(&env->log)) - return; - - linfo = find_linfo(env, insn_off); - if (!linfo || linfo == env->prev_linfo) - return; - - if (prefix_fmt) { - va_list args; - - va_start(args, prefix_fmt); - bpf_verifier_vlog(&env->log, prefix_fmt, args); - va_end(args); - } - - verbose(env, "%s\n", - ltrim(btf_name_by_offset(env->prog->aux->btf, - linfo->line_off))); - - env->prev_linfo = linfo; -} - static void verbose_invalid_scalar(struct bpf_verifier_env *env, struct bpf_reg_state *reg, struct tnum *range, const char *ctx, -- cgit v1.2.3 From 42feb6620accded89cad5f455665e21281813d79 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Fri, 17 Nov 2023 19:46:17 -0800 Subject: bpf: move verifier state printing code to kernel/bpf/log.c Move a good chunk of code from verifier.c to log.c: verifier state verbose printing logic. This is an important and very much logging/debugging oriented code. It fits the overlall log.c's focus on verifier logging, and moving it allows to keep growing it without unnecessarily adding to verifier.c code that otherwise contains a core verification logic. There are not many shared dependencies between this code and the rest of verifier.c code, except a few single-line helpers for various register type checks and a bit of state "scratching" helpers. We move all such trivial helpers into include/bpf/bpf_verifier.h as static inlines. No functional changes in this patch. Acked-by: Eduard Zingerman Acked-by: Stanislav Fomichev Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231118034623.3320920-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf_verifier.h | 72 ++++++++ kernel/bpf/log.c | 342 ++++++++++++++++++++++++++++++++++++ kernel/bpf/verifier.c | 403 ------------------------------------------- 3 files changed, 414 insertions(+), 403 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index d896f3db6a22..39edc76f436e 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -783,4 +783,76 @@ static inline bool bpf_type_has_unsafe_modifiers(u32 type) return type_flag(type) & ~BPF_REG_TRUSTED_MODIFIERS; } +static inline bool type_is_ptr_alloc_obj(u32 type) +{ + return base_type(type) == PTR_TO_BTF_ID && type_flag(type) & MEM_ALLOC; +} + +static inline bool type_is_non_owning_ref(u32 type) +{ + return type_is_ptr_alloc_obj(type) && type_flag(type) & NON_OWN_REF; +} + +static inline bool type_is_pkt_pointer(enum bpf_reg_type type) +{ + type = base_type(type); + return type == PTR_TO_PACKET || + type == PTR_TO_PACKET_META; +} + +static inline bool type_is_sk_pointer(enum bpf_reg_type type) +{ + return type == PTR_TO_SOCKET || + type == PTR_TO_SOCK_COMMON || + type == PTR_TO_TCP_SOCK || + type == PTR_TO_XDP_SOCK; +} + +static inline void mark_reg_scratched(struct bpf_verifier_env *env, u32 regno) +{ + env->scratched_regs |= 1U << regno; +} + +static inline void mark_stack_slot_scratched(struct bpf_verifier_env *env, u32 spi) +{ + env->scratched_stack_slots |= 1ULL << spi; +} + +static inline bool reg_scratched(const struct bpf_verifier_env *env, u32 regno) +{ + return (env->scratched_regs >> regno) & 1; +} + +static inline bool stack_slot_scratched(const struct bpf_verifier_env *env, u64 regno) +{ + return (env->scratched_stack_slots >> regno) & 1; +} + +static inline bool verifier_state_scratched(const struct bpf_verifier_env *env) +{ + return env->scratched_regs || env->scratched_stack_slots; +} + +static inline void mark_verifier_state_clean(struct bpf_verifier_env *env) +{ + env->scratched_regs = 0U; + env->scratched_stack_slots = 0ULL; +} + +/* Used for printing the entire verifier state. */ +static inline void mark_verifier_state_scratched(struct bpf_verifier_env *env) +{ + env->scratched_regs = ~0U; + env->scratched_stack_slots = ~0ULL; +} + +const char *reg_type_str(struct bpf_verifier_env *env, enum bpf_reg_type type); +const char *dynptr_type_str(enum bpf_dynptr_type type); +const char *iter_type_str(const struct btf *btf, u32 btf_id); +const char *iter_state_str(enum bpf_iter_state state); + +void print_verifier_state(struct bpf_verifier_env *env, + const struct bpf_func_state *state, bool print_all); +void print_insn_state(struct bpf_verifier_env *env, const struct bpf_func_state *state); + #endif /* _LINUX_BPF_VERIFIER_H */ diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c index f20e1449c882..c1b257eac21b 100644 --- a/kernel/bpf/log.c +++ b/kernel/bpf/log.c @@ -384,3 +384,345 @@ __printf(3, 4) void verbose_linfo(struct bpf_verifier_env *env, env->prev_linfo = linfo; } + +static const char *btf_type_name(const struct btf *btf, u32 id) +{ + return btf_name_by_offset(btf, btf_type_by_id(btf, id)->name_off); +} + +/* string representation of 'enum bpf_reg_type' + * + * Note that reg_type_str() can not appear more than once in a single verbose() + * statement. + */ +const char *reg_type_str(struct bpf_verifier_env *env, enum bpf_reg_type type) +{ + char postfix[16] = {0}, prefix[64] = {0}; + static const char * const str[] = { + [NOT_INIT] = "?", + [SCALAR_VALUE] = "scalar", + [PTR_TO_CTX] = "ctx", + [CONST_PTR_TO_MAP] = "map_ptr", + [PTR_TO_MAP_VALUE] = "map_value", + [PTR_TO_STACK] = "fp", + [PTR_TO_PACKET] = "pkt", + [PTR_TO_PACKET_META] = "pkt_meta", + [PTR_TO_PACKET_END] = "pkt_end", + [PTR_TO_FLOW_KEYS] = "flow_keys", + [PTR_TO_SOCKET] = "sock", + [PTR_TO_SOCK_COMMON] = "sock_common", + [PTR_TO_TCP_SOCK] = "tcp_sock", + [PTR_TO_TP_BUFFER] = "tp_buffer", + [PTR_TO_XDP_SOCK] = "xdp_sock", + [PTR_TO_BTF_ID] = "ptr_", + [PTR_TO_MEM] = "mem", + [PTR_TO_BUF] = "buf", + [PTR_TO_FUNC] = "func", + [PTR_TO_MAP_KEY] = "map_key", + [CONST_PTR_TO_DYNPTR] = "dynptr_ptr", + }; + + if (type & PTR_MAYBE_NULL) { + if (base_type(type) == PTR_TO_BTF_ID) + strncpy(postfix, "or_null_", 16); + else + strncpy(postfix, "_or_null", 16); + } + + snprintf(prefix, sizeof(prefix), "%s%s%s%s%s%s%s", + type & MEM_RDONLY ? "rdonly_" : "", + type & MEM_RINGBUF ? "ringbuf_" : "", + type & MEM_USER ? "user_" : "", + type & MEM_PERCPU ? "percpu_" : "", + type & MEM_RCU ? "rcu_" : "", + type & PTR_UNTRUSTED ? "untrusted_" : "", + type & PTR_TRUSTED ? "trusted_" : "" + ); + + snprintf(env->tmp_str_buf, TMP_STR_BUF_LEN, "%s%s%s", + prefix, str[base_type(type)], postfix); + return env->tmp_str_buf; +} + +const char *dynptr_type_str(enum bpf_dynptr_type type) +{ + switch (type) { + case BPF_DYNPTR_TYPE_LOCAL: + return "local"; + case BPF_DYNPTR_TYPE_RINGBUF: + return "ringbuf"; + case BPF_DYNPTR_TYPE_SKB: + return "skb"; + case BPF_DYNPTR_TYPE_XDP: + return "xdp"; + case BPF_DYNPTR_TYPE_INVALID: + return ""; + default: + WARN_ONCE(1, "unknown dynptr type %d\n", type); + return ""; + } +} + +const char *iter_type_str(const struct btf *btf, u32 btf_id) +{ + if (!btf || btf_id == 0) + return ""; + + /* we already validated that type is valid and has conforming name */ + return btf_type_name(btf, btf_id) + sizeof(ITER_PREFIX) - 1; +} + +const char *iter_state_str(enum bpf_iter_state state) +{ + switch (state) { + case BPF_ITER_STATE_ACTIVE: + return "active"; + case BPF_ITER_STATE_DRAINED: + return "drained"; + case BPF_ITER_STATE_INVALID: + return ""; + default: + WARN_ONCE(1, "unknown iter state %d\n", state); + return ""; + } +} + +static char slot_type_char[] = { + [STACK_INVALID] = '?', + [STACK_SPILL] = 'r', + [STACK_MISC] = 'm', + [STACK_ZERO] = '0', + [STACK_DYNPTR] = 'd', + [STACK_ITER] = 'i', +}; + +static void print_liveness(struct bpf_verifier_env *env, + enum bpf_reg_liveness live) +{ + if (live & (REG_LIVE_READ | REG_LIVE_WRITTEN | REG_LIVE_DONE)) + verbose(env, "_"); + if (live & REG_LIVE_READ) + verbose(env, "r"); + if (live & REG_LIVE_WRITTEN) + verbose(env, "w"); + if (live & REG_LIVE_DONE) + verbose(env, "D"); +} + +static void print_scalar_ranges(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, + const char **sep) +{ + struct { + const char *name; + u64 val; + bool omit; + } minmaxs[] = { + {"smin", reg->smin_value, reg->smin_value == S64_MIN}, + {"smax", reg->smax_value, reg->smax_value == S64_MAX}, + {"umin", reg->umin_value, reg->umin_value == 0}, + {"umax", reg->umax_value, reg->umax_value == U64_MAX}, + {"smin32", (s64)reg->s32_min_value, reg->s32_min_value == S32_MIN}, + {"smax32", (s64)reg->s32_max_value, reg->s32_max_value == S32_MAX}, + {"umin32", reg->u32_min_value, reg->u32_min_value == 0}, + {"umax32", reg->u32_max_value, reg->u32_max_value == U32_MAX}, + }, *m1, *m2, *mend = &minmaxs[ARRAY_SIZE(minmaxs)]; + bool neg1, neg2; + + for (m1 = &minmaxs[0]; m1 < mend; m1++) { + if (m1->omit) + continue; + + neg1 = m1->name[0] == 's' && (s64)m1->val < 0; + + verbose(env, "%s%s=", *sep, m1->name); + *sep = ","; + + for (m2 = m1 + 2; m2 < mend; m2 += 2) { + if (m2->omit || m2->val != m1->val) + continue; + /* don't mix negatives with positives */ + neg2 = m2->name[0] == 's' && (s64)m2->val < 0; + if (neg2 != neg1) + continue; + m2->omit = true; + verbose(env, "%s=", m2->name); + } + + verbose(env, m1->name[0] == 's' ? "%lld" : "%llu", m1->val); + } +} + +void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_state *state, + bool print_all) +{ + const struct bpf_reg_state *reg; + enum bpf_reg_type t; + int i; + + if (state->frameno) + verbose(env, " frame%d:", state->frameno); + for (i = 0; i < MAX_BPF_REG; i++) { + reg = &state->regs[i]; + t = reg->type; + if (t == NOT_INIT) + continue; + if (!print_all && !reg_scratched(env, i)) + continue; + verbose(env, " R%d", i); + print_liveness(env, reg->live); + verbose(env, "="); + if (t == SCALAR_VALUE && reg->precise) + verbose(env, "P"); + if ((t == SCALAR_VALUE || t == PTR_TO_STACK) && + tnum_is_const(reg->var_off)) { + /* reg->off should be 0 for SCALAR_VALUE */ + verbose(env, "%s", t == SCALAR_VALUE ? "" : reg_type_str(env, t)); + verbose(env, "%lld", reg->var_off.value + reg->off); + } else { + const char *sep = ""; + + verbose(env, "%s", reg_type_str(env, t)); + if (base_type(t) == PTR_TO_BTF_ID) + verbose(env, "%s", btf_type_name(reg->btf, reg->btf_id)); + verbose(env, "("); +/* + * _a stands for append, was shortened to avoid multiline statements below. + * This macro is used to output a comma separated list of attributes. + */ +#define verbose_a(fmt, ...) ({ verbose(env, "%s" fmt, sep, __VA_ARGS__); sep = ","; }) + + if (reg->id) + verbose_a("id=%d", reg->id); + if (reg->ref_obj_id) + verbose_a("ref_obj_id=%d", reg->ref_obj_id); + if (type_is_non_owning_ref(reg->type)) + verbose_a("%s", "non_own_ref"); + if (t != SCALAR_VALUE) + verbose_a("off=%d", reg->off); + if (type_is_pkt_pointer(t)) + verbose_a("r=%d", reg->range); + else if (base_type(t) == CONST_PTR_TO_MAP || + base_type(t) == PTR_TO_MAP_KEY || + base_type(t) == PTR_TO_MAP_VALUE) + verbose_a("ks=%d,vs=%d", + reg->map_ptr->key_size, + reg->map_ptr->value_size); + if (tnum_is_const(reg->var_off)) { + /* Typically an immediate SCALAR_VALUE, but + * could be a pointer whose offset is too big + * for reg->off + */ + verbose_a("imm=%llx", reg->var_off.value); + } else { + print_scalar_ranges(env, reg, &sep); + if (!tnum_is_unknown(reg->var_off)) { + char tn_buf[48]; + + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose_a("var_off=%s", tn_buf); + } + } +#undef verbose_a + + verbose(env, ")"); + } + } + for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { + char types_buf[BPF_REG_SIZE + 1]; + bool valid = false; + int j; + + for (j = 0; j < BPF_REG_SIZE; j++) { + if (state->stack[i].slot_type[j] != STACK_INVALID) + valid = true; + types_buf[j] = slot_type_char[state->stack[i].slot_type[j]]; + } + types_buf[BPF_REG_SIZE] = 0; + if (!valid) + continue; + if (!print_all && !stack_slot_scratched(env, i)) + continue; + switch (state->stack[i].slot_type[BPF_REG_SIZE - 1]) { + case STACK_SPILL: + reg = &state->stack[i].spilled_ptr; + t = reg->type; + + verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); + print_liveness(env, reg->live); + verbose(env, "=%s", t == SCALAR_VALUE ? "" : reg_type_str(env, t)); + if (t == SCALAR_VALUE && reg->precise) + verbose(env, "P"); + if (t == SCALAR_VALUE && tnum_is_const(reg->var_off)) + verbose(env, "%lld", reg->var_off.value + reg->off); + break; + case STACK_DYNPTR: + i += BPF_DYNPTR_NR_SLOTS - 1; + reg = &state->stack[i].spilled_ptr; + + verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); + print_liveness(env, reg->live); + verbose(env, "=dynptr_%s", dynptr_type_str(reg->dynptr.type)); + if (reg->ref_obj_id) + verbose(env, "(ref_id=%d)", reg->ref_obj_id); + break; + case STACK_ITER: + /* only main slot has ref_obj_id set; skip others */ + reg = &state->stack[i].spilled_ptr; + if (!reg->ref_obj_id) + continue; + + verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); + print_liveness(env, reg->live); + verbose(env, "=iter_%s(ref_id=%d,state=%s,depth=%u)", + iter_type_str(reg->iter.btf, reg->iter.btf_id), + reg->ref_obj_id, iter_state_str(reg->iter.state), + reg->iter.depth); + break; + case STACK_MISC: + case STACK_ZERO: + default: + reg = &state->stack[i].spilled_ptr; + + for (j = 0; j < BPF_REG_SIZE; j++) + types_buf[j] = slot_type_char[state->stack[i].slot_type[j]]; + types_buf[BPF_REG_SIZE] = 0; + + verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); + print_liveness(env, reg->live); + verbose(env, "=%s", types_buf); + break; + } + } + if (state->acquired_refs && state->refs[0].id) { + verbose(env, " refs=%d", state->refs[0].id); + for (i = 1; i < state->acquired_refs; i++) + if (state->refs[i].id) + verbose(env, ",%d", state->refs[i].id); + } + if (state->in_callback_fn) + verbose(env, " cb"); + if (state->in_async_callback_fn) + verbose(env, " async_cb"); + verbose(env, "\n"); + if (!print_all) + mark_verifier_state_clean(env); +} + +static inline u32 vlog_alignment(u32 pos) +{ + return round_up(max(pos + BPF_LOG_MIN_ALIGNMENT / 2, BPF_LOG_ALIGNMENT), + BPF_LOG_MIN_ALIGNMENT) - pos - 1; +} + +void print_insn_state(struct bpf_verifier_env *env, const struct bpf_func_state *state) +{ + if (env->prev_log_pos && env->prev_log_pos == env->log.end_pos) { + /* remove new line character */ + bpf_vlog_reset(&env->log, env->prev_log_pos - 1); + verbose(env, "%*c;", vlog_alignment(env->prev_insn_print_pos), ' '); + } else { + verbose(env, "%d:", env->insn_idx); + } + print_verifier_state(env, state, false); +} diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 683fdda25c13..8c2d31aa3d31 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -368,21 +368,6 @@ static void verbose_invalid_scalar(struct bpf_verifier_env *env, verbose(env, " should have been in %s\n", tn_buf); } -static bool type_is_pkt_pointer(enum bpf_reg_type type) -{ - type = base_type(type); - return type == PTR_TO_PACKET || - type == PTR_TO_PACKET_META; -} - -static bool type_is_sk_pointer(enum bpf_reg_type type) -{ - return type == PTR_TO_SOCKET || - type == PTR_TO_SOCK_COMMON || - type == PTR_TO_TCP_SOCK || - type == PTR_TO_XDP_SOCK; -} - static bool type_may_be_null(u32 type) { return type & PTR_MAYBE_NULL; @@ -406,16 +391,6 @@ static bool reg_not_null(const struct bpf_reg_state *reg) type == PTR_TO_MEM; } -static bool type_is_ptr_alloc_obj(u32 type) -{ - return base_type(type) == PTR_TO_BTF_ID && type_flag(type) & MEM_ALLOC; -} - -static bool type_is_non_owning_ref(u32 type) -{ - return type_is_ptr_alloc_obj(type) && type_flag(type) & NON_OWN_REF; -} - static struct btf_record *reg_btf_record(const struct bpf_reg_state *reg) { struct btf_record *rec = NULL; @@ -532,83 +507,6 @@ static bool is_cmpxchg_insn(const struct bpf_insn *insn) insn->imm == BPF_CMPXCHG; } -/* string representation of 'enum bpf_reg_type' - * - * Note that reg_type_str() can not appear more than once in a single verbose() - * statement. - */ -static const char *reg_type_str(struct bpf_verifier_env *env, - enum bpf_reg_type type) -{ - char postfix[16] = {0}, prefix[64] = {0}; - static const char * const str[] = { - [NOT_INIT] = "?", - [SCALAR_VALUE] = "scalar", - [PTR_TO_CTX] = "ctx", - [CONST_PTR_TO_MAP] = "map_ptr", - [PTR_TO_MAP_VALUE] = "map_value", - [PTR_TO_STACK] = "fp", - [PTR_TO_PACKET] = "pkt", - [PTR_TO_PACKET_META] = "pkt_meta", - [PTR_TO_PACKET_END] = "pkt_end", - [PTR_TO_FLOW_KEYS] = "flow_keys", - [PTR_TO_SOCKET] = "sock", - [PTR_TO_SOCK_COMMON] = "sock_common", - [PTR_TO_TCP_SOCK] = "tcp_sock", - [PTR_TO_TP_BUFFER] = "tp_buffer", - [PTR_TO_XDP_SOCK] = "xdp_sock", - [PTR_TO_BTF_ID] = "ptr_", - [PTR_TO_MEM] = "mem", - [PTR_TO_BUF] = "buf", - [PTR_TO_FUNC] = "func", - [PTR_TO_MAP_KEY] = "map_key", - [CONST_PTR_TO_DYNPTR] = "dynptr_ptr", - }; - - if (type & PTR_MAYBE_NULL) { - if (base_type(type) == PTR_TO_BTF_ID) - strncpy(postfix, "or_null_", 16); - else - strncpy(postfix, "_or_null", 16); - } - - snprintf(prefix, sizeof(prefix), "%s%s%s%s%s%s%s", - type & MEM_RDONLY ? "rdonly_" : "", - type & MEM_RINGBUF ? "ringbuf_" : "", - type & MEM_USER ? "user_" : "", - type & MEM_PERCPU ? "percpu_" : "", - type & MEM_RCU ? "rcu_" : "", - type & PTR_UNTRUSTED ? "untrusted_" : "", - type & PTR_TRUSTED ? "trusted_" : "" - ); - - snprintf(env->tmp_str_buf, TMP_STR_BUF_LEN, "%s%s%s", - prefix, str[base_type(type)], postfix); - return env->tmp_str_buf; -} - -static char slot_type_char[] = { - [STACK_INVALID] = '?', - [STACK_SPILL] = 'r', - [STACK_MISC] = 'm', - [STACK_ZERO] = '0', - [STACK_DYNPTR] = 'd', - [STACK_ITER] = 'i', -}; - -static void print_liveness(struct bpf_verifier_env *env, - enum bpf_reg_liveness live) -{ - if (live & (REG_LIVE_READ | REG_LIVE_WRITTEN | REG_LIVE_DONE)) - verbose(env, "_"); - if (live & REG_LIVE_READ) - verbose(env, "r"); - if (live & REG_LIVE_WRITTEN) - verbose(env, "w"); - if (live & REG_LIVE_DONE) - verbose(env, "D"); -} - static int __get_spi(s32 off) { return (-off - 1) / BPF_REG_SIZE; @@ -678,87 +576,6 @@ static const char *btf_type_name(const struct btf *btf, u32 id) return btf_name_by_offset(btf, btf_type_by_id(btf, id)->name_off); } -static const char *dynptr_type_str(enum bpf_dynptr_type type) -{ - switch (type) { - case BPF_DYNPTR_TYPE_LOCAL: - return "local"; - case BPF_DYNPTR_TYPE_RINGBUF: - return "ringbuf"; - case BPF_DYNPTR_TYPE_SKB: - return "skb"; - case BPF_DYNPTR_TYPE_XDP: - return "xdp"; - case BPF_DYNPTR_TYPE_INVALID: - return ""; - default: - WARN_ONCE(1, "unknown dynptr type %d\n", type); - return ""; - } -} - -static const char *iter_type_str(const struct btf *btf, u32 btf_id) -{ - if (!btf || btf_id == 0) - return ""; - - /* we already validated that type is valid and has conforming name */ - return btf_type_name(btf, btf_id) + sizeof(ITER_PREFIX) - 1; -} - -static const char *iter_state_str(enum bpf_iter_state state) -{ - switch (state) { - case BPF_ITER_STATE_ACTIVE: - return "active"; - case BPF_ITER_STATE_DRAINED: - return "drained"; - case BPF_ITER_STATE_INVALID: - return ""; - default: - WARN_ONCE(1, "unknown iter state %d\n", state); - return ""; - } -} - -static void mark_reg_scratched(struct bpf_verifier_env *env, u32 regno) -{ - env->scratched_regs |= 1U << regno; -} - -static void mark_stack_slot_scratched(struct bpf_verifier_env *env, u32 spi) -{ - env->scratched_stack_slots |= 1ULL << spi; -} - -static bool reg_scratched(const struct bpf_verifier_env *env, u32 regno) -{ - return (env->scratched_regs >> regno) & 1; -} - -static bool stack_slot_scratched(const struct bpf_verifier_env *env, u64 regno) -{ - return (env->scratched_stack_slots >> regno) & 1; -} - -static bool verifier_state_scratched(const struct bpf_verifier_env *env) -{ - return env->scratched_regs || env->scratched_stack_slots; -} - -static void mark_verifier_state_clean(struct bpf_verifier_env *env) -{ - env->scratched_regs = 0U; - env->scratched_stack_slots = 0ULL; -} - -/* Used for printing the entire verifier state. */ -static void mark_verifier_state_scratched(struct bpf_verifier_env *env) -{ - env->scratched_regs = ~0U; - env->scratched_stack_slots = ~0ULL; -} - static enum bpf_dynptr_type arg_to_dynptr_type(enum bpf_arg_type arg_type) { switch (arg_type & DYNPTR_TYPE_FLAG_MASK) { @@ -1298,226 +1115,6 @@ static void scrub_spilled_slot(u8 *stype) *stype = STACK_MISC; } -static void print_scalar_ranges(struct bpf_verifier_env *env, - const struct bpf_reg_state *reg, - const char **sep) -{ - struct { - const char *name; - u64 val; - bool omit; - } minmaxs[] = { - {"smin", reg->smin_value, reg->smin_value == S64_MIN}, - {"smax", reg->smax_value, reg->smax_value == S64_MAX}, - {"umin", reg->umin_value, reg->umin_value == 0}, - {"umax", reg->umax_value, reg->umax_value == U64_MAX}, - {"smin32", (s64)reg->s32_min_value, reg->s32_min_value == S32_MIN}, - {"smax32", (s64)reg->s32_max_value, reg->s32_max_value == S32_MAX}, - {"umin32", reg->u32_min_value, reg->u32_min_value == 0}, - {"umax32", reg->u32_max_value, reg->u32_max_value == U32_MAX}, - }, *m1, *m2, *mend = &minmaxs[ARRAY_SIZE(minmaxs)]; - bool neg1, neg2; - - for (m1 = &minmaxs[0]; m1 < mend; m1++) { - if (m1->omit) - continue; - - neg1 = m1->name[0] == 's' && (s64)m1->val < 0; - - verbose(env, "%s%s=", *sep, m1->name); - *sep = ","; - - for (m2 = m1 + 2; m2 < mend; m2 += 2) { - if (m2->omit || m2->val != m1->val) - continue; - /* don't mix negatives with positives */ - neg2 = m2->name[0] == 's' && (s64)m2->val < 0; - if (neg2 != neg1) - continue; - m2->omit = true; - verbose(env, "%s=", m2->name); - } - - verbose(env, m1->name[0] == 's' ? "%lld" : "%llu", m1->val); - } -} - -static void print_verifier_state(struct bpf_verifier_env *env, - const struct bpf_func_state *state, - bool print_all) -{ - const struct bpf_reg_state *reg; - enum bpf_reg_type t; - int i; - - if (state->frameno) - verbose(env, " frame%d:", state->frameno); - for (i = 0; i < MAX_BPF_REG; i++) { - reg = &state->regs[i]; - t = reg->type; - if (t == NOT_INIT) - continue; - if (!print_all && !reg_scratched(env, i)) - continue; - verbose(env, " R%d", i); - print_liveness(env, reg->live); - verbose(env, "="); - if (t == SCALAR_VALUE && reg->precise) - verbose(env, "P"); - if ((t == SCALAR_VALUE || t == PTR_TO_STACK) && - tnum_is_const(reg->var_off)) { - /* reg->off should be 0 for SCALAR_VALUE */ - verbose(env, "%s", t == SCALAR_VALUE ? "" : reg_type_str(env, t)); - verbose(env, "%lld", reg->var_off.value + reg->off); - } else { - const char *sep = ""; - - verbose(env, "%s", reg_type_str(env, t)); - if (base_type(t) == PTR_TO_BTF_ID) - verbose(env, "%s", btf_type_name(reg->btf, reg->btf_id)); - verbose(env, "("); -/* - * _a stands for append, was shortened to avoid multiline statements below. - * This macro is used to output a comma separated list of attributes. - */ -#define verbose_a(fmt, ...) ({ verbose(env, "%s" fmt, sep, __VA_ARGS__); sep = ","; }) - - if (reg->id) - verbose_a("id=%d", reg->id); - if (reg->ref_obj_id) - verbose_a("ref_obj_id=%d", reg->ref_obj_id); - if (type_is_non_owning_ref(reg->type)) - verbose_a("%s", "non_own_ref"); - if (t != SCALAR_VALUE) - verbose_a("off=%d", reg->off); - if (type_is_pkt_pointer(t)) - verbose_a("r=%d", reg->range); - else if (base_type(t) == CONST_PTR_TO_MAP || - base_type(t) == PTR_TO_MAP_KEY || - base_type(t) == PTR_TO_MAP_VALUE) - verbose_a("ks=%d,vs=%d", - reg->map_ptr->key_size, - reg->map_ptr->value_size); - if (tnum_is_const(reg->var_off)) { - /* Typically an immediate SCALAR_VALUE, but - * could be a pointer whose offset is too big - * for reg->off - */ - verbose_a("imm=%llx", reg->var_off.value); - } else { - print_scalar_ranges(env, reg, &sep); - if (!tnum_is_unknown(reg->var_off)) { - char tn_buf[48]; - - tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); - verbose_a("var_off=%s", tn_buf); - } - } -#undef verbose_a - - verbose(env, ")"); - } - } - for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { - char types_buf[BPF_REG_SIZE + 1]; - bool valid = false; - int j; - - for (j = 0; j < BPF_REG_SIZE; j++) { - if (state->stack[i].slot_type[j] != STACK_INVALID) - valid = true; - types_buf[j] = slot_type_char[state->stack[i].slot_type[j]]; - } - types_buf[BPF_REG_SIZE] = 0; - if (!valid) - continue; - if (!print_all && !stack_slot_scratched(env, i)) - continue; - switch (state->stack[i].slot_type[BPF_REG_SIZE - 1]) { - case STACK_SPILL: - reg = &state->stack[i].spilled_ptr; - t = reg->type; - - verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); - print_liveness(env, reg->live); - verbose(env, "=%s", t == SCALAR_VALUE ? "" : reg_type_str(env, t)); - if (t == SCALAR_VALUE && reg->precise) - verbose(env, "P"); - if (t == SCALAR_VALUE && tnum_is_const(reg->var_off)) - verbose(env, "%lld", reg->var_off.value + reg->off); - break; - case STACK_DYNPTR: - i += BPF_DYNPTR_NR_SLOTS - 1; - reg = &state->stack[i].spilled_ptr; - - verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); - print_liveness(env, reg->live); - verbose(env, "=dynptr_%s", dynptr_type_str(reg->dynptr.type)); - if (reg->ref_obj_id) - verbose(env, "(ref_id=%d)", reg->ref_obj_id); - break; - case STACK_ITER: - /* only main slot has ref_obj_id set; skip others */ - reg = &state->stack[i].spilled_ptr; - if (!reg->ref_obj_id) - continue; - - verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); - print_liveness(env, reg->live); - verbose(env, "=iter_%s(ref_id=%d,state=%s,depth=%u)", - iter_type_str(reg->iter.btf, reg->iter.btf_id), - reg->ref_obj_id, iter_state_str(reg->iter.state), - reg->iter.depth); - break; - case STACK_MISC: - case STACK_ZERO: - default: - reg = &state->stack[i].spilled_ptr; - - for (j = 0; j < BPF_REG_SIZE; j++) - types_buf[j] = slot_type_char[state->stack[i].slot_type[j]]; - types_buf[BPF_REG_SIZE] = 0; - - verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); - print_liveness(env, reg->live); - verbose(env, "=%s", types_buf); - break; - } - } - if (state->acquired_refs && state->refs[0].id) { - verbose(env, " refs=%d", state->refs[0].id); - for (i = 1; i < state->acquired_refs; i++) - if (state->refs[i].id) - verbose(env, ",%d", state->refs[i].id); - } - if (state->in_callback_fn) - verbose(env, " cb"); - if (state->in_async_callback_fn) - verbose(env, " async_cb"); - verbose(env, "\n"); - if (!print_all) - mark_verifier_state_clean(env); -} - -static inline u32 vlog_alignment(u32 pos) -{ - return round_up(max(pos + BPF_LOG_MIN_ALIGNMENT / 2, BPF_LOG_ALIGNMENT), - BPF_LOG_MIN_ALIGNMENT) - pos - 1; -} - -static void print_insn_state(struct bpf_verifier_env *env, - const struct bpf_func_state *state) -{ - if (env->prev_log_pos && env->prev_log_pos == env->log.end_pos) { - /* remove new line character */ - bpf_vlog_reset(&env->log, env->prev_log_pos - 1); - verbose(env, "%*c;", vlog_alignment(env->prev_insn_print_pos), ' '); - } else { - verbose(env, "%d:", env->insn_idx); - } - print_verifier_state(env, state, false); -} - /* copy array src of length n * size bytes to dst. dst is reallocated if it's too * small to hold src. This is different from krealloc since we don't want to preserve * the contents of dst. -- cgit v1.2.3 From 009f5465be3636e9ce795cfbd5d3109d8978774d Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Fri, 17 Nov 2023 19:46:18 -0800 Subject: bpf: extract register state printing Extract printing register state representation logic into a separate helper, as we are going to reuse it for spilled register state printing in the next patch. This also nicely reduces code nestedness. No functional changes. Acked-by: Eduard Zingerman Acked-by: Stanislav Fomichev Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231118034623.3320920-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/log.c | 120 +++++++++++++++++++++++++++++-------------------------- 1 file changed, 63 insertions(+), 57 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c index c1b257eac21b..05d737e2fab3 100644 --- a/kernel/bpf/log.c +++ b/kernel/bpf/log.c @@ -553,6 +553,67 @@ static void print_scalar_ranges(struct bpf_verifier_env *env, } } +static void print_reg_state(struct bpf_verifier_env *env, const struct bpf_reg_state *reg) +{ + enum bpf_reg_type t; + const char *sep = ""; + + t = reg->type; + if (t == SCALAR_VALUE && reg->precise) + verbose(env, "P"); + if ((t == SCALAR_VALUE || t == PTR_TO_STACK) && + tnum_is_const(reg->var_off)) { + /* reg->off should be 0 for SCALAR_VALUE */ + verbose(env, "%s", t == SCALAR_VALUE ? "" : reg_type_str(env, t)); + verbose(env, "%lld", reg->var_off.value + reg->off); + return; + } +/* + * _a stands for append, was shortened to avoid multiline statements below. + * This macro is used to output a comma separated list of attributes. + */ +#define verbose_a(fmt, ...) ({ verbose(env, "%s" fmt, sep, __VA_ARGS__); sep = ","; }) + + verbose(env, "%s", reg_type_str(env, t)); + if (base_type(t) == PTR_TO_BTF_ID) + verbose(env, "%s", btf_type_name(reg->btf, reg->btf_id)); + verbose(env, "("); + if (reg->id) + verbose_a("id=%d", reg->id); + if (reg->ref_obj_id) + verbose_a("ref_obj_id=%d", reg->ref_obj_id); + if (type_is_non_owning_ref(reg->type)) + verbose_a("%s", "non_own_ref"); + if (t != SCALAR_VALUE) + verbose_a("off=%d", reg->off); + if (type_is_pkt_pointer(t)) + verbose_a("r=%d", reg->range); + else if (base_type(t) == CONST_PTR_TO_MAP || + base_type(t) == PTR_TO_MAP_KEY || + base_type(t) == PTR_TO_MAP_VALUE) + verbose_a("ks=%d,vs=%d", + reg->map_ptr->key_size, + reg->map_ptr->value_size); + if (tnum_is_const(reg->var_off)) { + /* Typically an immediate SCALAR_VALUE, but + * could be a pointer whose offset is too big + * for reg->off + */ + verbose_a("imm=%llx", reg->var_off.value); + } else { + print_scalar_ranges(env, reg, &sep); + if (!tnum_is_unknown(reg->var_off)) { + char tn_buf[48]; + + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose_a("var_off=%s", tn_buf); + } + } + verbose(env, ")"); + +#undef verbose_a +} + void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_state *state, bool print_all) { @@ -564,69 +625,14 @@ void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_st verbose(env, " frame%d:", state->frameno); for (i = 0; i < MAX_BPF_REG; i++) { reg = &state->regs[i]; - t = reg->type; - if (t == NOT_INIT) + if (reg->type == NOT_INIT) continue; if (!print_all && !reg_scratched(env, i)) continue; verbose(env, " R%d", i); print_liveness(env, reg->live); verbose(env, "="); - if (t == SCALAR_VALUE && reg->precise) - verbose(env, "P"); - if ((t == SCALAR_VALUE || t == PTR_TO_STACK) && - tnum_is_const(reg->var_off)) { - /* reg->off should be 0 for SCALAR_VALUE */ - verbose(env, "%s", t == SCALAR_VALUE ? "" : reg_type_str(env, t)); - verbose(env, "%lld", reg->var_off.value + reg->off); - } else { - const char *sep = ""; - - verbose(env, "%s", reg_type_str(env, t)); - if (base_type(t) == PTR_TO_BTF_ID) - verbose(env, "%s", btf_type_name(reg->btf, reg->btf_id)); - verbose(env, "("); -/* - * _a stands for append, was shortened to avoid multiline statements below. - * This macro is used to output a comma separated list of attributes. - */ -#define verbose_a(fmt, ...) ({ verbose(env, "%s" fmt, sep, __VA_ARGS__); sep = ","; }) - - if (reg->id) - verbose_a("id=%d", reg->id); - if (reg->ref_obj_id) - verbose_a("ref_obj_id=%d", reg->ref_obj_id); - if (type_is_non_owning_ref(reg->type)) - verbose_a("%s", "non_own_ref"); - if (t != SCALAR_VALUE) - verbose_a("off=%d", reg->off); - if (type_is_pkt_pointer(t)) - verbose_a("r=%d", reg->range); - else if (base_type(t) == CONST_PTR_TO_MAP || - base_type(t) == PTR_TO_MAP_KEY || - base_type(t) == PTR_TO_MAP_VALUE) - verbose_a("ks=%d,vs=%d", - reg->map_ptr->key_size, - reg->map_ptr->value_size); - if (tnum_is_const(reg->var_off)) { - /* Typically an immediate SCALAR_VALUE, but - * could be a pointer whose offset is too big - * for reg->off - */ - verbose_a("imm=%llx", reg->var_off.value); - } else { - print_scalar_ranges(env, reg, &sep); - if (!tnum_is_unknown(reg->var_off)) { - char tn_buf[48]; - - tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); - verbose_a("var_off=%s", tn_buf); - } - } -#undef verbose_a - - verbose(env, ")"); - } + print_reg_state(env, reg); } for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { char types_buf[BPF_REG_SIZE + 1]; -- cgit v1.2.3 From 67d43dfbb42d6575304daea67733c88fbf536a1c Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Fri, 17 Nov 2023 19:46:19 -0800 Subject: bpf: print spilled register state in stack slot Print the same register state representation when printing stack state, as we do for normal registers. Note that if stack slot contains subregister spill (1, 2, or 4 byte long), we'll still emit "m0?" mask for those bytes that are not part of spilled register. While means we can get something like fp-8=0000scalar() for a 4-byte spill with other 4 bytes still being STACK_ZERO. Some example before and after, taken from the log of pyperf_subprogs.bpf.o: 49: (7b) *(u64 *)(r10 -256) = r1 ; frame1: R1_w=ctx(off=0,imm=0) R10=fp0 fp-256_w=ctx 49: (7b) *(u64 *)(r10 -256) = r1 ; frame1: R1_w=ctx(off=0,imm=0) R10=fp0 fp-256_w=ctx(off=0,imm=0) 150: (7b) *(u64 *)(r10 -264) = r0 ; frame1: R0_w=map_value_or_null(id=6,off=0,ks=192,vs=4,imm=0) R10=fp0 fp-264_w=map_value_or_null 150: (7b) *(u64 *)(r10 -264) = r0 ; frame1: R0_w=map_value_or_null(id=6,off=0,ks=192,vs=4,imm=0) R10=fp0 fp-264_w=map_value_or_null(id=6,off=0,ks=192,vs=4,imm=0) 5192: (61) r1 = *(u32 *)(r10 -272) ; frame1: R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=15,var_off=(0x0; 0xf)) R10=fp0 fp-272= 5192: (61) r1 = *(u32 *)(r10 -272) ; frame1: R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=15,var_off=(0x0; 0xf)) R10=fp0 fp-272=????scalar(smin=smin32=0,smax=umax=smax32=umax32=15,var_off=(0x0; 0xf)) While at it, do a few other simple clean ups: - skip slot if it's not scratched before detecting whether it's valid; - move taking spilled_reg pointer outside of switch (only DYNPTR has to adjust that to get to the "main" slot); - don't recalculate types_buf second time for MISC/ZERO/default case. Acked-by: Eduard Zingerman Acked-by: Stanislav Fomichev Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231118034623.3320920-5-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/log.c | 36 +++++++++++++++++------------------- 1 file changed, 17 insertions(+), 19 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c index 05d737e2fab3..97a1641e848e 100644 --- a/kernel/bpf/log.c +++ b/kernel/bpf/log.c @@ -618,7 +618,6 @@ void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_st bool print_all) { const struct bpf_reg_state *reg; - enum bpf_reg_type t; int i; if (state->frameno) @@ -637,32 +636,38 @@ void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_st for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { char types_buf[BPF_REG_SIZE + 1]; bool valid = false; + u8 slot_type; int j; + if (!print_all && !stack_slot_scratched(env, i)) + continue; + for (j = 0; j < BPF_REG_SIZE; j++) { - if (state->stack[i].slot_type[j] != STACK_INVALID) + slot_type = state->stack[i].slot_type[j]; + if (slot_type != STACK_INVALID) valid = true; - types_buf[j] = slot_type_char[state->stack[i].slot_type[j]]; + types_buf[j] = slot_type_char[slot_type]; } types_buf[BPF_REG_SIZE] = 0; if (!valid) continue; - if (!print_all && !stack_slot_scratched(env, i)) - continue; + + reg = &state->stack[i].spilled_ptr; switch (state->stack[i].slot_type[BPF_REG_SIZE - 1]) { case STACK_SPILL: - reg = &state->stack[i].spilled_ptr; - t = reg->type; + /* print MISC/ZERO/INVALID slots above subreg spill */ + for (j = 0; j < BPF_REG_SIZE; j++) + if (state->stack[i].slot_type[j] == STACK_SPILL) + break; + types_buf[j] = '\0'; verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); print_liveness(env, reg->live); - verbose(env, "=%s", t == SCALAR_VALUE ? "" : reg_type_str(env, t)); - if (t == SCALAR_VALUE && reg->precise) - verbose(env, "P"); - if (t == SCALAR_VALUE && tnum_is_const(reg->var_off)) - verbose(env, "%lld", reg->var_off.value + reg->off); + verbose(env, "=%s", types_buf); + print_reg_state(env, reg); break; case STACK_DYNPTR: + /* skip to main dynptr slot */ i += BPF_DYNPTR_NR_SLOTS - 1; reg = &state->stack[i].spilled_ptr; @@ -674,7 +679,6 @@ void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_st break; case STACK_ITER: /* only main slot has ref_obj_id set; skip others */ - reg = &state->stack[i].spilled_ptr; if (!reg->ref_obj_id) continue; @@ -688,12 +692,6 @@ void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_st case STACK_MISC: case STACK_ZERO: default: - reg = &state->stack[i].spilled_ptr; - - for (j = 0; j < BPF_REG_SIZE; j++) - types_buf[j] = slot_type_char[state->stack[i].slot_type[j]]; - types_buf[BPF_REG_SIZE] = 0; - verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); print_liveness(env, reg->live); verbose(env, "=%s", types_buf); -- cgit v1.2.3 From 0c95c9fdb696f35c7864785ba84cb9a50152daff Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Fri, 17 Nov 2023 19:46:20 -0800 Subject: bpf: emit map name in register state if applicable and available In complicated real-world applications, whenever debugging some verification error through verifier log, it often would be very useful to see map name for PTR_TO_MAP_VALUE register. Usually this needs to be inferred from key/value sizes and maybe trying to guess C code location, but it's not always clear. Given verifier has the name, and it's never too long, let's just emit it for ptr_to_map_key, ptr_to_map_value, and const_ptr_to_map registers. We reshuffle the order a bit, so that map name, key size, and value size appear before offset and immediate values, which seems like a more logical order. Current output: R1_w=map_ptr(map=array_map,ks=4,vs=8,off=0,imm=0) But we'll get rid of useless off=0 and imm=0 parts in the next patch. Acked-by: Eduard Zingerman Acked-by: Stanislav Fomichev Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231118034623.3320920-6-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/log.c | 24 ++++++++++++++++------ tools/testing/selftests/bpf/prog_tests/spin_lock.c | 10 ++++----- 2 files changed, 23 insertions(+), 11 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c index 97a1641e848e..c209ab1ec2b5 100644 --- a/kernel/bpf/log.c +++ b/kernel/bpf/log.c @@ -553,6 +553,17 @@ static void print_scalar_ranges(struct bpf_verifier_env *env, } } +static bool type_is_map_ptr(enum bpf_reg_type t) { + switch (base_type(t)) { + case CONST_PTR_TO_MAP: + case PTR_TO_MAP_KEY: + case PTR_TO_MAP_VALUE: + return true; + default: + return false; + } +} + static void print_reg_state(struct bpf_verifier_env *env, const struct bpf_reg_state *reg) { enum bpf_reg_type t; @@ -584,16 +595,17 @@ static void print_reg_state(struct bpf_verifier_env *env, const struct bpf_reg_s verbose_a("ref_obj_id=%d", reg->ref_obj_id); if (type_is_non_owning_ref(reg->type)) verbose_a("%s", "non_own_ref"); + if (type_is_map_ptr(t)) { + if (reg->map_ptr->name[0]) + verbose_a("map=%s", reg->map_ptr->name); + verbose_a("ks=%d,vs=%d", + reg->map_ptr->key_size, + reg->map_ptr->value_size); + } if (t != SCALAR_VALUE) verbose_a("off=%d", reg->off); if (type_is_pkt_pointer(t)) verbose_a("r=%d", reg->range); - else if (base_type(t) == CONST_PTR_TO_MAP || - base_type(t) == PTR_TO_MAP_KEY || - base_type(t) == PTR_TO_MAP_VALUE) - verbose_a("ks=%d,vs=%d", - reg->map_ptr->key_size, - reg->map_ptr->value_size); if (tnum_is_const(reg->var_off)) { /* Typically an immediate SCALAR_VALUE, but * could be a pointer whose offset is too big diff --git a/tools/testing/selftests/bpf/prog_tests/spin_lock.c b/tools/testing/selftests/bpf/prog_tests/spin_lock.c index f29c08d93beb..ace65224286f 100644 --- a/tools/testing/selftests/bpf/prog_tests/spin_lock.c +++ b/tools/testing/selftests/bpf/prog_tests/spin_lock.c @@ -17,18 +17,18 @@ static struct { "R1_w=ptr_foo(id=2,ref_obj_id=2,off=0,imm=0) refs=2\n6: (85) call bpf_this_cpu_ptr#154\n" "R1 type=ptr_ expected=percpu_ptr_" }, { "lock_id_global_zero", - "; R1_w=map_value(off=0,ks=4,vs=4,imm=0)\n2: (85) call bpf_this_cpu_ptr#154\n" + "; R1_w=map_value(map=.data.A,ks=4,vs=4,off=0,imm=0)\n2: (85) call bpf_this_cpu_ptr#154\n" "R1 type=map_value expected=percpu_ptr_" }, { "lock_id_mapval_preserve", "[0-9]\\+: (bf) r1 = r0 ;" - " R0_w=map_value(id=1,off=0,ks=4,vs=8,imm=0)" - " R1_w=map_value(id=1,off=0,ks=4,vs=8,imm=0)\n" + " R0_w=map_value(id=1,map=array_map,ks=4,vs=8,off=0,imm=0)" + " R1_w=map_value(id=1,map=array_map,ks=4,vs=8,off=0,imm=0)\n" "[0-9]\\+: (85) call bpf_this_cpu_ptr#154\n" "R1 type=map_value expected=percpu_ptr_" }, { "lock_id_innermapval_preserve", "[0-9]\\+: (bf) r1 = r0 ;" - " R0=map_value(id=2,off=0,ks=4,vs=8,imm=0)" - " R1_w=map_value(id=2,off=0,ks=4,vs=8,imm=0)\n" + " R0=map_value(id=2,ks=4,vs=8,off=0,imm=0)" + " R1_w=map_value(id=2,ks=4,vs=8,off=0,imm=0)\n" "[0-9]\\+: (85) call bpf_this_cpu_ptr#154\n" "R1 type=map_value expected=percpu_ptr_" }, { "lock_id_mismatch_kptr_kptr", "bpf_spin_unlock of different lock" }, -- cgit v1.2.3 From 1db747d75b1dbe17bf4283ed87bd3b7a92010f34 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Fri, 17 Nov 2023 19:46:21 -0800 Subject: bpf: omit default off=0 and imm=0 in register state log Simplify BPF verifier log further by omitting default (and frequently irrelevant) off=0 and imm=0 parts for non-SCALAR_VALUE registers. As can be seen from fixed tests, this is often a visual noise for PTR_TO_CTX register and even for PTR_TO_PACKET registers. Omitting default values follows the rest of register state logic: we omit default values to keep verifier log succinct and to highlight interesting state that deviates from default one. E.g., we do the same for var_off, when it's unknown, which gives no additional information. Acked-by: Eduard Zingerman Acked-by: Stanislav Fomichev Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231118034623.3320920-7-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/log.c | 10 +++--- tools/testing/selftests/bpf/prog_tests/align.c | 42 +++++++++++----------- tools/testing/selftests/bpf/prog_tests/log_buf.c | 4 +-- tools/testing/selftests/bpf/prog_tests/spin_lock.c | 14 ++++---- .../selftests/bpf/progs/exceptions_assert.c | 10 +++--- 5 files changed, 39 insertions(+), 41 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c index c209ab1ec2b5..20b4f81087da 100644 --- a/kernel/bpf/log.c +++ b/kernel/bpf/log.c @@ -602,16 +602,14 @@ static void print_reg_state(struct bpf_verifier_env *env, const struct bpf_reg_s reg->map_ptr->key_size, reg->map_ptr->value_size); } - if (t != SCALAR_VALUE) + if (t != SCALAR_VALUE && reg->off) verbose_a("off=%d", reg->off); if (type_is_pkt_pointer(t)) verbose_a("r=%d", reg->range); if (tnum_is_const(reg->var_off)) { - /* Typically an immediate SCALAR_VALUE, but - * could be a pointer whose offset is too big - * for reg->off - */ - verbose_a("imm=%llx", reg->var_off.value); + /* a pointer register with fixed offset */ + if (reg->var_off.value) + verbose_a("imm=%llx", reg->var_off.value); } else { print_scalar_ranges(env, reg, &sep); if (!tnum_is_unknown(reg->var_off)) { diff --git a/tools/testing/selftests/bpf/prog_tests/align.c b/tools/testing/selftests/bpf/prog_tests/align.c index 465c1c3a3d3c..4ebd0da898f5 100644 --- a/tools/testing/selftests/bpf/prog_tests/align.c +++ b/tools/testing/selftests/bpf/prog_tests/align.c @@ -40,7 +40,7 @@ static struct bpf_align_test tests[] = { }, .prog_type = BPF_PROG_TYPE_SCHED_CLS, .matches = { - {0, "R1", "ctx(off=0,imm=0)"}, + {0, "R1", "ctx()"}, {0, "R10", "fp0"}, {0, "R3_w", "2"}, {1, "R3_w", "4"}, @@ -68,7 +68,7 @@ static struct bpf_align_test tests[] = { }, .prog_type = BPF_PROG_TYPE_SCHED_CLS, .matches = { - {0, "R1", "ctx(off=0,imm=0)"}, + {0, "R1", "ctx()"}, {0, "R10", "fp0"}, {0, "R3_w", "1"}, {1, "R3_w", "2"}, @@ -97,7 +97,7 @@ static struct bpf_align_test tests[] = { }, .prog_type = BPF_PROG_TYPE_SCHED_CLS, .matches = { - {0, "R1", "ctx(off=0,imm=0)"}, + {0, "R1", "ctx()"}, {0, "R10", "fp0"}, {0, "R3_w", "4"}, {1, "R3_w", "8"}, @@ -119,7 +119,7 @@ static struct bpf_align_test tests[] = { }, .prog_type = BPF_PROG_TYPE_SCHED_CLS, .matches = { - {0, "R1", "ctx(off=0,imm=0)"}, + {0, "R1", "ctx()"}, {0, "R10", "fp0"}, {0, "R3_w", "7"}, {1, "R3_w", "7"}, @@ -162,13 +162,13 @@ static struct bpf_align_test tests[] = { }, .prog_type = BPF_PROG_TYPE_SCHED_CLS, .matches = { - {6, "R0_w", "pkt(off=8,r=8,imm=0)"}, + {6, "R0_w", "pkt(off=8,r=8)"}, {6, "R3_w", "var_off=(0x0; 0xff)"}, {7, "R3_w", "var_off=(0x0; 0x1fe)"}, {8, "R3_w", "var_off=(0x0; 0x3fc)"}, {9, "R3_w", "var_off=(0x0; 0x7f8)"}, {10, "R3_w", "var_off=(0x0; 0xff0)"}, - {12, "R3_w", "pkt_end(off=0,imm=0)"}, + {12, "R3_w", "pkt_end()"}, {17, "R4_w", "var_off=(0x0; 0xff)"}, {18, "R4_w", "var_off=(0x0; 0x1fe0)"}, {19, "R4_w", "var_off=(0x0; 0xff0)"}, @@ -235,11 +235,11 @@ static struct bpf_align_test tests[] = { }, .prog_type = BPF_PROG_TYPE_SCHED_CLS, .matches = { - {2, "R5_w", "pkt(off=0,r=0,imm=0)"}, - {4, "R5_w", "pkt(off=14,r=0,imm=0)"}, - {5, "R4_w", "pkt(off=14,r=0,imm=0)"}, - {9, "R2", "pkt(off=0,r=18,imm=0)"}, - {10, "R5", "pkt(off=14,r=18,imm=0)"}, + {2, "R5_w", "pkt(r=0)"}, + {4, "R5_w", "pkt(off=14,r=0)"}, + {5, "R4_w", "pkt(off=14,r=0)"}, + {9, "R2", "pkt(r=18)"}, + {10, "R5", "pkt(off=14,r=18)"}, {10, "R4_w", "var_off=(0x0; 0xff)"}, {13, "R4_w", "var_off=(0x0; 0xffff)"}, {14, "R4_w", "var_off=(0x0; 0xffff)"}, @@ -299,7 +299,7 @@ static struct bpf_align_test tests[] = { /* Calculated offset in R6 has unknown value, but known * alignment of 4. */ - {6, "R2_w", "pkt(off=0,r=8,imm=0)"}, + {6, "R2_w", "pkt(r=8)"}, {7, "R6_w", "var_off=(0x0; 0x3fc)"}, /* Offset is added to packet pointer R5, resulting in * known fixed offset, and variable offset from R6. @@ -337,7 +337,7 @@ static struct bpf_align_test tests[] = { /* Constant offset is added to R5 packet pointer, * resulting in reg->off value of 14. */ - {26, "R5_w", "pkt(off=14,r=8,"}, + {26, "R5_w", "pkt(off=14,r=8)"}, /* Variable offset is added to R5, resulting in a * variable offset of (4n). See comment for insn #18 * for R4 = R5 trick. @@ -397,7 +397,7 @@ static struct bpf_align_test tests[] = { /* Calculated offset in R6 has unknown value, but known * alignment of 4. */ - {6, "R2_w", "pkt(off=0,r=8,imm=0)"}, + {6, "R2_w", "pkt(r=8)"}, {7, "R6_w", "var_off=(0x0; 0x3fc)"}, /* Adding 14 makes R6 be (4n+2) */ {8, "R6_w", "var_off=(0x2; 0x7fc)"}, @@ -459,7 +459,7 @@ static struct bpf_align_test tests[] = { .prog_type = BPF_PROG_TYPE_SCHED_CLS, .result = REJECT, .matches = { - {3, "R5_w", "pkt_end(off=0,imm=0)"}, + {3, "R5_w", "pkt_end()"}, /* (ptr - ptr) << 2 == unknown, (4n) */ {5, "R5_w", "var_off=(0x0; 0xfffffffffffffffc)"}, /* (4n) + 14 == (4n+2). We blow our bounds, because @@ -513,7 +513,7 @@ static struct bpf_align_test tests[] = { /* Calculated offset in R6 has unknown value, but known * alignment of 4. */ - {6, "R2_w", "pkt(off=0,r=8,imm=0)"}, + {6, "R2_w", "pkt(r=8)"}, {8, "R6_w", "var_off=(0x0; 0x3fc)"}, /* Adding 14 makes R6 be (4n+2) */ {9, "R6_w", "var_off=(0x2; 0x7fc)"}, @@ -566,7 +566,7 @@ static struct bpf_align_test tests[] = { /* Calculated offset in R6 has unknown value, but known * alignment of 4. */ - {6, "R2_w", "pkt(off=0,r=8,imm=0)"}, + {6, "R2_w", "pkt(r=8)"}, {9, "R6_w", "var_off=(0x0; 0x3c)"}, /* Adding 14 makes R6 be (4n+2) */ {10, "R6_w", "var_off=(0x2; 0x7c)"}, @@ -659,14 +659,14 @@ static int do_test_single(struct bpf_align_test *test) /* Check the next line as well in case the previous line * did not have a corresponding bpf insn. Example: * func#0 @0 - * 0: R1=ctx(off=0,imm=0) R10=fp0 + * 0: R1=ctx() R10=fp0 * 0: (b7) r3 = 2 ; R3_w=2 * * Sometimes it's actually two lines below, e.g. when * searching for "6: R3_w=scalar(umax=255,var_off=(0x0; 0xff))": - * from 4 to 6: R0_w=pkt(off=8,r=8,imm=0) R1=ctx(off=0,imm=0) R2_w=pkt(off=0,r=8,imm=0) R3_w=pkt_end(off=0,imm=0) R10=fp0 - * 6: R0_w=pkt(off=8,r=8,imm=0) R1=ctx(off=0,imm=0) R2_w=pkt(off=0,r=8,imm=0) R3_w=pkt_end(off=0,imm=0) R10=fp0 - * 6: (71) r3 = *(u8 *)(r2 +0) ; R2_w=pkt(off=0,r=8,imm=0) R3_w=scalar(umax=255,var_off=(0x0; 0xff)) + * from 4 to 6: R0_w=pkt(off=8,r=8) R1=ctx() R2_w=pkt(r=8) R3_w=pkt_end() R10=fp0 + * 6: R0_w=pkt(off=8,r=8) R1=ctx() R2_w=pkt(r=8) R3_w=pkt_end() R10=fp0 + * 6: (71) r3 = *(u8 *)(r2 +0) ; R2_w=pkt(r=8) R3_w=scalar(umax=255,var_off=(0x0; 0xff)) */ while (!(p = strstr(line_ptr, m.reg)) || !strstr(p, m.match)) { cur_line = -1; diff --git a/tools/testing/selftests/bpf/prog_tests/log_buf.c b/tools/testing/selftests/bpf/prog_tests/log_buf.c index fe9a23e65ef4..0f7ea4d7d9f6 100644 --- a/tools/testing/selftests/bpf/prog_tests/log_buf.c +++ b/tools/testing/selftests/bpf/prog_tests/log_buf.c @@ -78,7 +78,7 @@ static void obj_load_log_buf(void) ASSERT_OK_PTR(strstr(libbpf_log_buf, "prog 'bad_prog': BPF program load failed"), "libbpf_log_not_empty"); ASSERT_OK_PTR(strstr(obj_log_buf, "DATASEC license"), "obj_log_not_empty"); - ASSERT_OK_PTR(strstr(good_log_buf, "0: R1=ctx(off=0,imm=0) R10=fp0"), + ASSERT_OK_PTR(strstr(good_log_buf, "0: R1=ctx() R10=fp0"), "good_log_verbose"); ASSERT_OK_PTR(strstr(bad_log_buf, "invalid access to map value, value_size=16 off=16000 size=4"), "bad_log_not_empty"); @@ -175,7 +175,7 @@ static void bpf_prog_load_log_buf(void) opts.log_level = 2; fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, "good_prog", "GPL", good_prog_insns, good_prog_insn_cnt, &opts); - ASSERT_OK_PTR(strstr(log_buf, "0: R1=ctx(off=0,imm=0) R10=fp0"), "good_log_2"); + ASSERT_OK_PTR(strstr(log_buf, "0: R1=ctx() R10=fp0"), "good_log_2"); ASSERT_GE(fd, 0, "good_fd2"); if (fd >= 0) close(fd); diff --git a/tools/testing/selftests/bpf/prog_tests/spin_lock.c b/tools/testing/selftests/bpf/prog_tests/spin_lock.c index ace65224286f..18d451be57c8 100644 --- a/tools/testing/selftests/bpf/prog_tests/spin_lock.c +++ b/tools/testing/selftests/bpf/prog_tests/spin_lock.c @@ -13,22 +13,22 @@ static struct { const char *err_msg; } spin_lock_fail_tests[] = { { "lock_id_kptr_preserve", - "5: (bf) r1 = r0 ; R0_w=ptr_foo(id=2,ref_obj_id=2,off=0,imm=0) " - "R1_w=ptr_foo(id=2,ref_obj_id=2,off=0,imm=0) refs=2\n6: (85) call bpf_this_cpu_ptr#154\n" + "5: (bf) r1 = r0 ; R0_w=ptr_foo(id=2,ref_obj_id=2) " + "R1_w=ptr_foo(id=2,ref_obj_id=2) refs=2\n6: (85) call bpf_this_cpu_ptr#154\n" "R1 type=ptr_ expected=percpu_ptr_" }, { "lock_id_global_zero", - "; R1_w=map_value(map=.data.A,ks=4,vs=4,off=0,imm=0)\n2: (85) call bpf_this_cpu_ptr#154\n" + "; R1_w=map_value(map=.data.A,ks=4,vs=4)\n2: (85) call bpf_this_cpu_ptr#154\n" "R1 type=map_value expected=percpu_ptr_" }, { "lock_id_mapval_preserve", "[0-9]\\+: (bf) r1 = r0 ;" - " R0_w=map_value(id=1,map=array_map,ks=4,vs=8,off=0,imm=0)" - " R1_w=map_value(id=1,map=array_map,ks=4,vs=8,off=0,imm=0)\n" + " R0_w=map_value(id=1,map=array_map,ks=4,vs=8)" + " R1_w=map_value(id=1,map=array_map,ks=4,vs=8)\n" "[0-9]\\+: (85) call bpf_this_cpu_ptr#154\n" "R1 type=map_value expected=percpu_ptr_" }, { "lock_id_innermapval_preserve", "[0-9]\\+: (bf) r1 = r0 ;" - " R0=map_value(id=2,ks=4,vs=8,off=0,imm=0)" - " R1_w=map_value(id=2,ks=4,vs=8,off=0,imm=0)\n" + " R0=map_value(id=2,ks=4,vs=8)" + " R1_w=map_value(id=2,ks=4,vs=8)\n" "[0-9]\\+: (85) call bpf_this_cpu_ptr#154\n" "R1 type=map_value expected=percpu_ptr_" }, { "lock_id_mismatch_kptr_kptr", "bpf_spin_unlock of different lock" }, diff --git a/tools/testing/selftests/bpf/progs/exceptions_assert.c b/tools/testing/selftests/bpf/progs/exceptions_assert.c index e1e5c54a6a11..26f7d67432cc 100644 --- a/tools/testing/selftests/bpf/progs/exceptions_assert.c +++ b/tools/testing/selftests/bpf/progs/exceptions_assert.c @@ -59,7 +59,7 @@ check_assert(s64, ge, neg, INT_MIN); SEC("?tc") __log_level(2) __failure -__msg(": R0=0 R1=ctx(off=0,imm=0) R2=scalar(smin=smin32=-2147483646,smax=smax32=2147483645) R10=fp0") +__msg(": R0=0 R1=ctx() R2=scalar(smin=smin32=-2147483646,smax=smax32=2147483645) R10=fp0") int check_assert_range_s64(struct __sk_buff *ctx) { struct bpf_sock *sk = ctx->sk; @@ -75,7 +75,7 @@ int check_assert_range_s64(struct __sk_buff *ctx) SEC("?tc") __log_level(2) __failure -__msg(": R1=ctx(off=0,imm=0) R2=scalar(smin=umin=smin32=umin32=4096,smax=umax=smax32=umax32=8192,var_off=(0x0; 0x3fff))") +__msg(": R1=ctx() R2=scalar(smin=umin=smin32=umin32=4096,smax=umax=smax32=umax32=8192,var_off=(0x0; 0x3fff))") int check_assert_range_u64(struct __sk_buff *ctx) { u64 num = ctx->len; @@ -86,7 +86,7 @@ int check_assert_range_u64(struct __sk_buff *ctx) SEC("?tc") __log_level(2) __failure -__msg(": R0=0 R1=ctx(off=0,imm=0) R2=4096 R10=fp0") +__msg(": R0=0 R1=ctx() R2=4096 R10=fp0") int check_assert_single_range_s64(struct __sk_buff *ctx) { struct bpf_sock *sk = ctx->sk; @@ -103,7 +103,7 @@ int check_assert_single_range_s64(struct __sk_buff *ctx) SEC("?tc") __log_level(2) __failure -__msg(": R1=ctx(off=0,imm=0) R2=4096 R10=fp0") +__msg(": R1=ctx() R2=4096 R10=fp0") int check_assert_single_range_u64(struct __sk_buff *ctx) { u64 num = ctx->len; @@ -114,7 +114,7 @@ int check_assert_single_range_u64(struct __sk_buff *ctx) SEC("?tc") __log_level(2) __failure -__msg(": R1=pkt(off=64,r=64,imm=0) R2=pkt_end(off=0,imm=0) R6=pkt(off=0,r=64,imm=0) R10=fp0") +__msg(": R1=pkt(off=64,r=64) R2=pkt_end() R6=pkt(r=64) R10=fp0") int check_assert_generic(struct __sk_buff *ctx) { u8 *data_end = (void *)(long)ctx->data_end; -- cgit v1.2.3 From 0f8dbdbc641b45a5fa31d497f9fc83ffe1174fa3 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Fri, 17 Nov 2023 19:46:22 -0800 Subject: bpf: smarter verifier log number printing logic Instead of always printing numbers as either decimals (and in some cases, like for "imm=%llx", in hexadecimals), decide the form based on actual values. For numbers in a reasonably small range (currently, [0, U16_MAX] for unsigned values, and [S16_MIN, S16_MAX] for signed ones), emit them as decimals. In all other cases, even for signed values, emit them in hexadecimals. For large values hex form is often times way more useful: it's easier to see an exact difference between 0xffffffff80000000 and 0xffffffff7fffffff, than between 18446744071562067966 and 18446744071562067967, as one particular example. Small values representing small pointer offsets or application constants, on the other hand, are way more useful to be represented in decimal notation. Adjust reg_bounds register state parsing logic to take into account this change. Acked-by: Eduard Zingerman Acked-by: Stanislav Fomichev Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231118034623.3320920-8-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/log.c | 79 +++++++++++++++++++--- .../testing/selftests/bpf/prog_tests/reg_bounds.c | 53 +++++++++------ .../selftests/bpf/progs/exceptions_assert.c | 32 ++++----- 3 files changed, 118 insertions(+), 46 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c index 20b4f81087da..87105aa482ed 100644 --- a/kernel/bpf/log.c +++ b/kernel/bpf/log.c @@ -509,10 +509,52 @@ static void print_liveness(struct bpf_verifier_env *env, verbose(env, "D"); } +#define UNUM_MAX_DECIMAL U16_MAX +#define SNUM_MAX_DECIMAL S16_MAX +#define SNUM_MIN_DECIMAL S16_MIN + +static bool is_unum_decimal(u64 num) +{ + return num <= UNUM_MAX_DECIMAL; +} + +static bool is_snum_decimal(s64 num) +{ + return num >= SNUM_MIN_DECIMAL && num <= SNUM_MAX_DECIMAL; +} + +static void verbose_unum(struct bpf_verifier_env *env, u64 num) +{ + if (is_unum_decimal(num)) + verbose(env, "%llu", num); + else + verbose(env, "%#llx", num); +} + +static void verbose_snum(struct bpf_verifier_env *env, s64 num) +{ + if (is_snum_decimal(num)) + verbose(env, "%lld", num); + else + verbose(env, "%#llx", num); +} + static void print_scalar_ranges(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, const char **sep) { + /* For signed ranges, we want to unify 64-bit and 32-bit values in the + * output as much as possible, but there is a bit of a complication. + * If we choose to print values as decimals, this is natural to do, + * because negative 64-bit and 32-bit values >= -S32_MIN have the same + * representation due to sign extension. But if we choose to print + * them in hex format (see is_snum_decimal()), then sign extension is + * misleading. + * E.g., smin=-2 and smin32=-2 are exactly the same in decimal, but in + * hex they will be smin=0xfffffffffffffffe and smin32=0xfffffffe, two + * very different numbers. + * So we avoid sign extension if we choose to print values in hex. + */ struct { const char *name; u64 val; @@ -522,8 +564,14 @@ static void print_scalar_ranges(struct bpf_verifier_env *env, {"smax", reg->smax_value, reg->smax_value == S64_MAX}, {"umin", reg->umin_value, reg->umin_value == 0}, {"umax", reg->umax_value, reg->umax_value == U64_MAX}, - {"smin32", (s64)reg->s32_min_value, reg->s32_min_value == S32_MIN}, - {"smax32", (s64)reg->s32_max_value, reg->s32_max_value == S32_MAX}, + {"smin32", + is_snum_decimal((s64)reg->s32_min_value) + ? (s64)reg->s32_min_value + : (u32)reg->s32_min_value, reg->s32_min_value == S32_MIN}, + {"smax32", + is_snum_decimal((s64)reg->s32_max_value) + ? (s64)reg->s32_max_value + : (u32)reg->s32_max_value, reg->s32_max_value == S32_MAX}, {"umin32", reg->u32_min_value, reg->u32_min_value == 0}, {"umax32", reg->u32_max_value, reg->u32_max_value == U32_MAX}, }, *m1, *m2, *mend = &minmaxs[ARRAY_SIZE(minmaxs)]; @@ -549,7 +597,10 @@ static void print_scalar_ranges(struct bpf_verifier_env *env, verbose(env, "%s=", m2->name); } - verbose(env, m1->name[0] == 's' ? "%lld" : "%llu", m1->val); + if (m1->name[0] == 's') + verbose_snum(env, m1->val); + else + verbose_unum(env, m1->val); } } @@ -576,14 +627,14 @@ static void print_reg_state(struct bpf_verifier_env *env, const struct bpf_reg_s tnum_is_const(reg->var_off)) { /* reg->off should be 0 for SCALAR_VALUE */ verbose(env, "%s", t == SCALAR_VALUE ? "" : reg_type_str(env, t)); - verbose(env, "%lld", reg->var_off.value + reg->off); + verbose_snum(env, reg->var_off.value + reg->off); return; } /* * _a stands for append, was shortened to avoid multiline statements below. * This macro is used to output a comma separated list of attributes. */ -#define verbose_a(fmt, ...) ({ verbose(env, "%s" fmt, sep, __VA_ARGS__); sep = ","; }) +#define verbose_a(fmt, ...) ({ verbose(env, "%s" fmt, sep, ##__VA_ARGS__); sep = ","; }) verbose(env, "%s", reg_type_str(env, t)); if (base_type(t) == PTR_TO_BTF_ID) @@ -602,14 +653,20 @@ static void print_reg_state(struct bpf_verifier_env *env, const struct bpf_reg_s reg->map_ptr->key_size, reg->map_ptr->value_size); } - if (t != SCALAR_VALUE && reg->off) - verbose_a("off=%d", reg->off); - if (type_is_pkt_pointer(t)) - verbose_a("r=%d", reg->range); + if (t != SCALAR_VALUE && reg->off) { + verbose_a("off="); + verbose_snum(env, reg->off); + } + if (type_is_pkt_pointer(t)) { + verbose_a("r="); + verbose_unum(env, reg->range); + } if (tnum_is_const(reg->var_off)) { /* a pointer register with fixed offset */ - if (reg->var_off.value) - verbose_a("imm=%llx", reg->var_off.value); + if (reg->var_off.value) { + verbose_a("imm="); + verbose_snum(env, reg->var_off.value); + } } else { print_scalar_ranges(env, reg, &sep); if (!tnum_is_unknown(reg->var_off)) { diff --git a/tools/testing/selftests/bpf/prog_tests/reg_bounds.c b/tools/testing/selftests/bpf/prog_tests/reg_bounds.c index 7a8b0bf0a7f8..fd4ab23e6f54 100644 --- a/tools/testing/selftests/bpf/prog_tests/reg_bounds.c +++ b/tools/testing/selftests/bpf/prog_tests/reg_bounds.c @@ -13,10 +13,13 @@ */ #define U64_MAX ((u64)UINT64_MAX) #define U32_MAX ((u32)UINT_MAX) +#define U16_MAX ((u32)UINT_MAX) #define S64_MIN ((s64)INT64_MIN) #define S64_MAX ((s64)INT64_MAX) #define S32_MIN ((s32)INT_MIN) #define S32_MAX ((s32)INT_MAX) +#define S16_MIN ((s16)0x80000000) +#define S16_MAX ((s16)0x7fffffff) typedef unsigned long long ___u64; typedef unsigned int ___u32; @@ -138,13 +141,17 @@ static enum num_t t_unsigned(enum num_t t) } } +#define UNUM_MAX_DECIMAL U16_MAX +#define SNUM_MAX_DECIMAL S16_MAX +#define SNUM_MIN_DECIMAL S16_MIN + static bool num_is_small(enum num_t t, u64 x) { switch (t) { - case U64: return (u64)x <= 256; - case U32: return (u32)x <= 256; - case S64: return (s64)x >= -256 && (s64)x <= 256; - case S32: return (s32)x >= -256 && (s32)x <= 256; + case U64: return (u64)x <= UNUM_MAX_DECIMAL; + case U32: return (u32)x <= UNUM_MAX_DECIMAL; + case S64: return (s64)x >= SNUM_MIN_DECIMAL && (s64)x <= SNUM_MAX_DECIMAL; + case S32: return (s32)x >= SNUM_MIN_DECIMAL && (s32)x <= SNUM_MAX_DECIMAL; default: printf("num_is_small!\n"); exit(1); } } @@ -1023,20 +1030,19 @@ static int parse_reg_state(const char *s, struct reg_state *reg) */ struct { const char *pfx; - const char *fmt; u64 *dst, def; bool is_32, is_set; } *f, fields[8] = { - {"smin=", "%lld", ®->r[S64].a, S64_MIN}, - {"smax=", "%lld", ®->r[S64].b, S64_MAX}, - {"umin=", "%llu", ®->r[U64].a, 0}, - {"umax=", "%llu", ®->r[U64].b, U64_MAX}, - {"smin32=", "%lld", ®->r[S32].a, (u32)S32_MIN, true}, - {"smax32=", "%lld", ®->r[S32].b, (u32)S32_MAX, true}, - {"umin32=", "%llu", ®->r[U32].a, 0, true}, - {"umax32=", "%llu", ®->r[U32].b, U32_MAX, true}, + {"smin=", ®->r[S64].a, S64_MIN}, + {"smax=", ®->r[S64].b, S64_MAX}, + {"umin=", ®->r[U64].a, 0}, + {"umax=", ®->r[U64].b, U64_MAX}, + {"smin32=", ®->r[S32].a, (u32)S32_MIN, true}, + {"smax32=", ®->r[S32].b, (u32)S32_MAX, true}, + {"umin32=", ®->r[U32].a, 0, true}, + {"umax32=", ®->r[U32].b, U32_MAX, true}, }; - const char *p, *fmt; + const char *p; int i; p = strchr(s, '='); @@ -1050,8 +1056,13 @@ static int parse_reg_state(const char *s, struct reg_state *reg) long long sval; enum num_t t; - if (sscanf(p, "%lld", &sval) != 1) - return -EINVAL; + if (p[0] == '0' && p[1] == 'x') { + if (sscanf(p, "%llx", &sval) != 1) + return -EINVAL; + } else { + if (sscanf(p, "%lld", &sval) != 1) + return -EINVAL; + } reg->valid = true; for (t = first_t; t <= last_t; t++) { @@ -1075,9 +1086,13 @@ static int parse_reg_state(const char *s, struct reg_state *reg) if (mcnt) { /* populate all matched fields */ - fmt = fields[midxs[0]].fmt; - if (sscanf(p, fmt, &val) != 1) - return -EINVAL; + if (p[0] == '0' && p[1] == 'x') { + if (sscanf(p, "%llx", &val) != 1) + return -EINVAL; + } else { + if (sscanf(p, "%lld", &val) != 1) + return -EINVAL; + } for (i = 0; i < mcnt; i++) { f = &fields[midxs[i]]; diff --git a/tools/testing/selftests/bpf/progs/exceptions_assert.c b/tools/testing/selftests/bpf/progs/exceptions_assert.c index 26f7d67432cc..49efaed143fc 100644 --- a/tools/testing/selftests/bpf/progs/exceptions_assert.c +++ b/tools/testing/selftests/bpf/progs/exceptions_assert.c @@ -18,48 +18,48 @@ return *(u64 *)num; \ } -__msg(": R0_w=-2147483648 R10=fp0") +__msg(": R0_w=0xffffffff80000000 R10=fp0") check_assert(s64, eq, int_min, INT_MIN); -__msg(": R0_w=2147483647 R10=fp0") +__msg(": R0_w=0x7fffffff R10=fp0") check_assert(s64, eq, int_max, INT_MAX); __msg(": R0_w=0 R10=fp0") check_assert(s64, eq, zero, 0); -__msg(": R0_w=-9223372036854775808 R1_w=-9223372036854775808 R10=fp0") +__msg(": R0_w=0x8000000000000000 R1_w=0x8000000000000000 R10=fp0") check_assert(s64, eq, llong_min, LLONG_MIN); -__msg(": R0_w=9223372036854775807 R1_w=9223372036854775807 R10=fp0") +__msg(": R0_w=0x7fffffffffffffff R1_w=0x7fffffffffffffff R10=fp0") check_assert(s64, eq, llong_max, LLONG_MAX); -__msg(": R0_w=scalar(smax=2147483646) R10=fp0") +__msg(": R0_w=scalar(smax=0x7ffffffe) R10=fp0") check_assert(s64, lt, pos, INT_MAX); -__msg(": R0_w=scalar(smax=-1,umin=9223372036854775808,var_off=(0x8000000000000000; 0x7fffffffffffffff))") +__msg(": R0_w=scalar(smax=-1,umin=0x8000000000000000,var_off=(0x8000000000000000; 0x7fffffffffffffff))") check_assert(s64, lt, zero, 0); -__msg(": R0_w=scalar(smax=-2147483649,umin=9223372036854775808,umax=18446744071562067967,var_off=(0x8000000000000000; 0x7fffffffffffffff))") +__msg(": R0_w=scalar(smax=0xffffffff7fffffff,umin=0x8000000000000000,umax=0xffffffff7fffffff,var_off=(0x8000000000000000; 0x7fffffffffffffff))") check_assert(s64, lt, neg, INT_MIN); -__msg(": R0_w=scalar(smax=2147483647) R10=fp0") +__msg(": R0_w=scalar(smax=0x7fffffff) R10=fp0") check_assert(s64, le, pos, INT_MAX); __msg(": R0_w=scalar(smax=0) R10=fp0") check_assert(s64, le, zero, 0); -__msg(": R0_w=scalar(smax=-2147483648,umin=9223372036854775808,umax=18446744071562067968,var_off=(0x8000000000000000; 0x7fffffffffffffff))") +__msg(": R0_w=scalar(smax=0xffffffff80000000,umin=0x8000000000000000,umax=0xffffffff80000000,var_off=(0x8000000000000000; 0x7fffffffffffffff))") check_assert(s64, le, neg, INT_MIN); -__msg(": R0_w=scalar(smin=umin=2147483648,umax=9223372036854775807,var_off=(0x0; 0x7fffffffffffffff))") +__msg(": R0_w=scalar(smin=umin=0x80000000,umax=0x7fffffffffffffff,var_off=(0x0; 0x7fffffffffffffff))") check_assert(s64, gt, pos, INT_MAX); -__msg(": R0_w=scalar(smin=umin=1,umax=9223372036854775807,var_off=(0x0; 0x7fffffffffffffff))") +__msg(": R0_w=scalar(smin=umin=1,umax=0x7fffffffffffffff,var_off=(0x0; 0x7fffffffffffffff))") check_assert(s64, gt, zero, 0); -__msg(": R0_w=scalar(smin=-2147483647) R10=fp0") +__msg(": R0_w=scalar(smin=0xffffffff80000001) R10=fp0") check_assert(s64, gt, neg, INT_MIN); -__msg(": R0_w=scalar(smin=umin=2147483647,umax=9223372036854775807,var_off=(0x0; 0x7fffffffffffffff))") +__msg(": R0_w=scalar(smin=umin=0x7fffffff,umax=0x7fffffffffffffff,var_off=(0x0; 0x7fffffffffffffff))") check_assert(s64, ge, pos, INT_MAX); -__msg(": R0_w=scalar(smin=0,umax=9223372036854775807,var_off=(0x0; 0x7fffffffffffffff)) R10=fp0") +__msg(": R0_w=scalar(smin=0,umax=0x7fffffffffffffff,var_off=(0x0; 0x7fffffffffffffff)) R10=fp0") check_assert(s64, ge, zero, 0); -__msg(": R0_w=scalar(smin=-2147483648) R10=fp0") +__msg(": R0_w=scalar(smin=0xffffffff80000000) R10=fp0") check_assert(s64, ge, neg, INT_MIN); SEC("?tc") __log_level(2) __failure -__msg(": R0=0 R1=ctx() R2=scalar(smin=smin32=-2147483646,smax=smax32=2147483645) R10=fp0") +__msg(": R0=0 R1=ctx() R2=scalar(smin=0xffffffff80000002,smax=smax32=0x7ffffffd,smin32=0x80000002) R10=fp0") int check_assert_range_s64(struct __sk_buff *ctx) { struct bpf_sock *sk = ctx->sk; -- cgit v1.2.3 From 46862ee854b4f5a315d63b677ca3af14a89aefeb Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Fri, 17 Nov 2023 19:46:23 -0800 Subject: bpf: emit frameno for PTR_TO_STACK regs if it differs from current one It's possible to pass a pointer to parent's stack to child subprogs. In such case verifier state output is ambiguous not showing whether register container a pointer to "current" stack, belonging to current subprog (frame), or it's actually a pointer to one of parent frames. So emit this information if frame number differs between the state which register is part of. E.g., if current state is in frame 2 and it has a register pointing to stack in grand parent state (frame #0), we'll see something like 'R1=fp[0]-16', while "local stack pointer" will be just 'R2=fp-16'. Acked-by: Eduard Zingerman Acked-by: Stanislav Fomichev Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231118034623.3320920-9-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/log.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c index 87105aa482ed..3505f3e5ae96 100644 --- a/kernel/bpf/log.c +++ b/kernel/bpf/log.c @@ -615,7 +615,9 @@ static bool type_is_map_ptr(enum bpf_reg_type t) { } } -static void print_reg_state(struct bpf_verifier_env *env, const struct bpf_reg_state *reg) +static void print_reg_state(struct bpf_verifier_env *env, + const struct bpf_func_state *state, + const struct bpf_reg_state *reg) { enum bpf_reg_type t; const char *sep = ""; @@ -623,10 +625,8 @@ static void print_reg_state(struct bpf_verifier_env *env, const struct bpf_reg_s t = reg->type; if (t == SCALAR_VALUE && reg->precise) verbose(env, "P"); - if ((t == SCALAR_VALUE || t == PTR_TO_STACK) && - tnum_is_const(reg->var_off)) { + if (t == SCALAR_VALUE && tnum_is_const(reg->var_off)) { /* reg->off should be 0 for SCALAR_VALUE */ - verbose(env, "%s", t == SCALAR_VALUE ? "" : reg_type_str(env, t)); verbose_snum(env, reg->var_off.value + reg->off); return; } @@ -637,6 +637,14 @@ static void print_reg_state(struct bpf_verifier_env *env, const struct bpf_reg_s #define verbose_a(fmt, ...) ({ verbose(env, "%s" fmt, sep, ##__VA_ARGS__); sep = ","; }) verbose(env, "%s", reg_type_str(env, t)); + if (t == PTR_TO_STACK) { + if (state->frameno != reg->frameno) + verbose(env, "[%d]", reg->frameno); + if (tnum_is_const(reg->var_off)) { + verbose_snum(env, reg->var_off.value + reg->off); + return; + } + } if (base_type(t) == PTR_TO_BTF_ID) verbose(env, "%s", btf_type_name(reg->btf, reg->btf_id)); verbose(env, "("); @@ -698,7 +706,7 @@ void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_st verbose(env, " R%d", i); print_liveness(env, reg->live); verbose(env, "="); - print_reg_state(env, reg); + print_reg_state(env, state, reg); } for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { char types_buf[BPF_REG_SIZE + 1]; @@ -731,7 +739,7 @@ void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_st verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); print_liveness(env, reg->live); verbose(env, "=%s", types_buf); - print_reg_state(env, reg); + print_reg_state(env, state, reg); break; case STACK_DYNPTR: /* skip to main dynptr slot */ -- cgit v1.2.3 From 2d1618054f25e11c44d189dbff4a60342a4cfb4b Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Tue, 14 Nov 2023 17:32:34 +0100 Subject: bpf: task_group_seq_get_next: use __next_thread() rather than next_thread() Lockless use of next_thread() should be avoided, kernel/bpf/task_iter.c is the last user and the usage is wrong. task_group_seq_get_next() can return the group leader twice if it races with mt-thread exec which changes the group->leader's pid. Change the main loop to use __next_thread(), kill "next_tid == common->pid" check. __next_thread() can't loop forever, we can also change this code to retry if next_tid == 0. Signed-off-by: Oleg Nesterov Acked-by: Yonghong Song Link: https://lore.kernel.org/r/20231114163234.GA890@redhat.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/task_iter.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c index 26082b97894d..51ae15e2b290 100644 --- a/kernel/bpf/task_iter.c +++ b/kernel/bpf/task_iter.c @@ -70,15 +70,13 @@ static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_comm return NULL; retry: - task = next_thread(task); + task = __next_thread(task); + if (!task) + return NULL; next_tid = __task_pid_nr_ns(task, PIDTYPE_PID, common->ns); - if (!next_tid || next_tid == common->pid) { - /* Run out of tasks of a process. The tasks of a - * thread_group are linked as circular linked list. - */ - return NULL; - } + if (!next_tid) + goto retry; if (skip_if_dup_files && task->files == task->group_leader->files) goto retry; -- cgit v1.2.3 From 5a34f9dabd9aa567e2d37e1aa27a67f80acfaa1c Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Tue, 14 Nov 2023 17:32:37 +0100 Subject: bpf: bpf_iter_task_next: use __next_thread() rather than next_thread() Lockless use of next_thread() should be avoided, kernel/bpf/task_iter.c is the last user and the usage is wrong. bpf_iter_task_next() can loop forever, "kit->pos == kit->task" can never happen if kit->pos execs. Change this code to use __next_thread(). With or without this change the usage of kit->pos/task and next_task() doesn't look nice, see the next patch. Signed-off-by: Oleg Nesterov Acked-by: Yonghong Song Link: https://lore.kernel.org/r/20231114163237.GA897@redhat.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/task_iter.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c index 51ae15e2b290..d42e08d0d0b7 100644 --- a/kernel/bpf/task_iter.c +++ b/kernel/bpf/task_iter.c @@ -1015,12 +1015,11 @@ __bpf_kfunc struct task_struct *bpf_iter_task_next(struct bpf_iter_task *it) if (flags == BPF_TASK_ITER_ALL_PROCS) goto get_next_task; - kit->pos = next_thread(kit->pos); - if (kit->pos == kit->task) { - if (flags == BPF_TASK_ITER_PROC_THREADS) { - kit->pos = NULL; + kit->pos = __next_thread(kit->pos); + if (!kit->pos) { + if (flags == BPF_TASK_ITER_PROC_THREADS) return pos; - } + kit->pos = kit->task; } else return pos; -- cgit v1.2.3 From ac8148d957f50434411a0c15a2e4f352b5bb4ff2 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Tue, 14 Nov 2023 17:32:39 +0100 Subject: bpf: bpf_iter_task_next: use next_task(kit->task) rather than next_task(kit->pos) This looks more clear and simplifies the code. While at it, remove the unnecessary initialization of pos/task at the start of bpf_iter_task_new(). Note that we can even kill kit->task, we can just use pos->group_leader, but I don't understand the BUILD_BUG_ON() checks in bpf_iter_task_new(). Signed-off-by: Oleg Nesterov Acked-by: Yonghong Song Link: https://lore.kernel.org/r/20231114163239.GA903@redhat.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/task_iter.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c index d42e08d0d0b7..e5c3500443c6 100644 --- a/kernel/bpf/task_iter.c +++ b/kernel/bpf/task_iter.c @@ -978,7 +978,6 @@ __bpf_kfunc int bpf_iter_task_new(struct bpf_iter_task *it, BUILD_BUG_ON(__alignof__(struct bpf_iter_task_kern) != __alignof__(struct bpf_iter_task)); - kit->task = kit->pos = NULL; switch (flags) { case BPF_TASK_ITER_ALL_THREADS: case BPF_TASK_ITER_ALL_PROCS: @@ -1016,18 +1015,15 @@ __bpf_kfunc struct task_struct *bpf_iter_task_next(struct bpf_iter_task *it) goto get_next_task; kit->pos = __next_thread(kit->pos); - if (!kit->pos) { - if (flags == BPF_TASK_ITER_PROC_THREADS) - return pos; - kit->pos = kit->task; - } else + if (kit->pos || flags == BPF_TASK_ITER_PROC_THREADS) return pos; get_next_task: - kit->pos = next_task(kit->pos); - kit->task = kit->pos; - if (kit->pos == &init_task) + kit->task = next_task(kit->task); + if (kit->task == &init_task) kit->pos = NULL; + else + kit->pos = kit->task; return pos; } -- cgit v1.2.3 From 491dd8edecbc5027ee317f3f1e7e9800fb66d88f Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 23 Nov 2023 19:59:35 -0800 Subject: bpf: Emit global subprog name in verifier logs We have the name, instead of emitting just func#N to identify global subprog, augment verifier log messages with actual function name to make it more user-friendly. Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Acked-by: Eduard Zingerman Acked-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20231124035937.403208-2-andrii@kernel.org --- kernel/bpf/verifier.c | 35 ++++++++++++++++++++++++----------- 1 file changed, 24 insertions(+), 11 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 405da1f9e724..a2939ebf2638 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -339,6 +339,11 @@ struct bpf_kfunc_call_arg_meta { struct btf *btf_vmlinux; +static const char *btf_type_name(const struct btf *btf, u32 id) +{ + return btf_name_by_offset(btf, btf_type_by_id(btf, id)->name_off); +} + static DEFINE_MUTEX(bpf_verifier_lock); static DEFINE_MUTEX(bpf_percpu_ma_lock); @@ -418,6 +423,17 @@ static bool subprog_is_global(const struct bpf_verifier_env *env, int subprog) return aux && aux[subprog].linkage == BTF_FUNC_GLOBAL; } +static const char *subprog_name(const struct bpf_verifier_env *env, int subprog) +{ + struct bpf_func_info *info; + + if (!env->prog->aux->func_info) + return ""; + + info = &env->prog->aux->func_info[subprog]; + return btf_type_name(env->prog->aux->btf, info->type_id); +} + static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg) { return btf_record_has_field(reg_btf_record(reg), BPF_SPIN_LOCK); @@ -587,11 +603,6 @@ static int iter_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg, return stack_slot_obj_get_spi(env, reg, "iter", nr_slots); } -static const char *btf_type_name(const struct btf *btf, u32 id) -{ - return btf_name_by_offset(btf, btf_type_by_id(btf, id)->name_off); -} - static enum bpf_dynptr_type arg_to_dynptr_type(enum bpf_arg_type arg_type) { switch (arg_type & DYNPTR_TYPE_FLAG_MASK) { @@ -9269,13 +9280,16 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, if (err == -EFAULT) return err; if (subprog_is_global(env, subprog)) { + const char *sub_name = subprog_name(env, subprog); + if (err) { - verbose(env, "Caller passes invalid args into func#%d\n", subprog); + verbose(env, "Caller passes invalid args into func#%d ('%s')\n", + subprog, sub_name); return err; } - if (env->log.level & BPF_LOG_LEVEL) - verbose(env, "Func#%d is global and valid. Skipping.\n", subprog); + verbose(env, "Func#%d ('%s') is global and assumed valid.\n", + subprog, sub_name); clear_caller_saved_regs(env, caller->regs); /* All global functions return a 64-bit SCALAR_VALUE */ @@ -19893,9 +19907,8 @@ static int do_check_subprogs(struct bpf_verifier_env *env) if (ret) { return ret; } else if (env->log.level & BPF_LOG_LEVEL) { - verbose(env, - "Func#%d is safe for any args that match its prototype\n", - i); + verbose(env, "Func#%d ('%s') is safe for any args that match its prototype\n", + i, subprog_name(env, i)); } } return 0; -- cgit v1.2.3 From 2afae08c9dcb8ac648414277cec70c2fe6a34d9e Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 23 Nov 2023 19:59:36 -0800 Subject: bpf: Validate global subprogs lazily Slightly change BPF verifier logic around eagerness and order of global subprog validation. Instead of going over every global subprog eagerly and validating it before main (entry) BPF program is verified, turn it around. Validate main program first, mark subprogs that were called from main program for later verification, but otherwise assume it is valid. Afterwards, go over marked global subprogs and validate those, potentially marking some more global functions as being called. Continue this process until all (transitively) callable global subprogs are validated. It's a BFS traversal at its heart and will always converge. This is an important change because it allows to feature-gate some subprograms that might not be verifiable on some older kernel, depending on supported set of features. E.g., at some point, global functions were allowed to accept a pointer to memory, which size is identified by user-provided type. Unfortunately, older kernels don't support this feature. With BPF CO-RE approach, the natural way would be to still compile BPF object file once and guard calls to this global subprog with some CO-RE check or using .rodata variables. That's what people do to guard usage of new helpers or kfuncs, and any other new BPF-side feature that might be missing on old kernels. That's currently impossible to do with global subprogs, unfortunately, because they are eagerly and unconditionally validated. This patch set aims to change this, so that in the future when global funcs gain new features, those can be guarded using BPF CO-RE techniques in the same fashion as any other new kernel feature. Two selftests had to be adjusted in sync with these changes. test_global_func12 relied on eager global subprog validation failing before main program failure is detected (unknown return value). Fix by making sure that main program is always valid. verifier_subprog_precision's parent_stack_slot_precise subtest relied on verifier checkpointing heuristic to do a checkpoint at instruction #5, but that's no longer true because we don't have enough jumps validated before reaching insn #5 due to global subprogs being validated later. Other than that, no changes, as one would expect. Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Acked-by: Eduard Zingerman Acked-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20231124035937.403208-3-andrii@kernel.org --- include/linux/bpf.h | 2 + kernel/bpf/verifier.c | 48 +++++++++++++++++++--- .../selftests/bpf/progs/test_global_func12.c | 4 +- .../bpf/progs/verifier_subprog_precision.c | 4 +- 4 files changed, 48 insertions(+), 10 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 258ba232e302..eb447b0a9423 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1347,6 +1347,8 @@ static inline bool bpf_prog_has_trampoline(const struct bpf_prog *prog) struct bpf_func_info_aux { u16 linkage; bool unreliable; + bool called : 1; + bool verified : 1; }; enum bpf_jit_poke_reason { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index a2939ebf2638..8e7b6072e3f4 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -434,6 +434,11 @@ static const char *subprog_name(const struct bpf_verifier_env *env, int subprog) return btf_type_name(env->prog->aux->btf, info->type_id); } +static struct bpf_func_info_aux *subprog_aux(const struct bpf_verifier_env *env, int subprog) +{ + return &env->prog->aux->func_info_aux[subprog]; +} + static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg) { return btf_record_has_field(reg_btf_record(reg), BPF_SPIN_LOCK); @@ -9290,6 +9295,8 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, verbose(env, "Func#%d ('%s') is global and assumed valid.\n", subprog, sub_name); + /* mark global subprog for verifying after main prog */ + subprog_aux(env, subprog)->called = true; clear_caller_saved_regs(env, caller->regs); /* All global functions return a 64-bit SCALAR_VALUE */ @@ -19873,8 +19880,11 @@ out: return ret; } -/* Verify all global functions in a BPF program one by one based on their BTF. - * All global functions must pass verification. Otherwise the whole program is rejected. +/* Lazily verify all global functions based on their BTF, if they are called + * from main BPF program or any of subprograms transitively. + * BPF global subprogs called from dead code are not validated. + * All callable global functions must pass verification. + * Otherwise the whole program is rejected. * Consider: * int bar(int); * int foo(int f) @@ -19893,14 +19903,26 @@ out: static int do_check_subprogs(struct bpf_verifier_env *env) { struct bpf_prog_aux *aux = env->prog->aux; - int i, ret; + struct bpf_func_info_aux *sub_aux; + int i, ret, new_cnt; if (!aux->func_info) return 0; + /* exception callback is presumed to be always called */ + if (env->exception_callback_subprog) + subprog_aux(env, env->exception_callback_subprog)->called = true; + +again: + new_cnt = 0; for (i = 1; i < env->subprog_cnt; i++) { - if (aux->func_info_aux[i].linkage != BTF_FUNC_GLOBAL) + if (!subprog_is_global(env, i)) + continue; + + sub_aux = subprog_aux(env, i); + if (!sub_aux->called || sub_aux->verified) continue; + env->insn_idx = env->subprog_info[i].start; WARN_ON_ONCE(env->insn_idx == 0); ret = do_check_common(env, i, env->exception_callback_subprog == i); @@ -19910,7 +19932,21 @@ static int do_check_subprogs(struct bpf_verifier_env *env) verbose(env, "Func#%d ('%s') is safe for any args that match its prototype\n", i, subprog_name(env, i)); } + + /* We verified new global subprog, it might have called some + * more global subprogs that we haven't verified yet, so we + * need to do another pass over subprogs to verify those. + */ + sub_aux->verified = true; + new_cnt++; } + + /* We can't loop forever as we verify at least one global subprog on + * each pass. + */ + if (new_cnt) + goto again; + return 0; } @@ -20556,8 +20592,8 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u3 if (ret < 0) goto skip_full_check; - ret = do_check_subprogs(env); - ret = ret ?: do_check_main(env); + ret = do_check_main(env); + ret = ret ?: do_check_subprogs(env); if (ret == 0 && bpf_prog_is_offloaded(env->prog->aux)) ret = bpf_prog_offload_finalize(env); diff --git a/tools/testing/selftests/bpf/progs/test_global_func12.c b/tools/testing/selftests/bpf/progs/test_global_func12.c index 7f159d83c6f6..6e03d42519a6 100644 --- a/tools/testing/selftests/bpf/progs/test_global_func12.c +++ b/tools/testing/selftests/bpf/progs/test_global_func12.c @@ -19,5 +19,7 @@ int global_func12(struct __sk_buff *skb) { const struct S s = {.x = skb->len }; - return foo(&s); + foo(&s); + + return 1; } diff --git a/tools/testing/selftests/bpf/progs/verifier_subprog_precision.c b/tools/testing/selftests/bpf/progs/verifier_subprog_precision.c index f61d623b1ce8..b5efcaeaa1ae 100644 --- a/tools/testing/selftests/bpf/progs/verifier_subprog_precision.c +++ b/tools/testing/selftests/bpf/progs/verifier_subprog_precision.c @@ -370,12 +370,10 @@ __naked int parent_stack_slot_precise(void) SEC("?raw_tp") __success __log_level(2) __msg("9: (0f) r1 += r6") -__msg("mark_precise: frame0: last_idx 9 first_idx 6") +__msg("mark_precise: frame0: last_idx 9 first_idx 0") __msg("mark_precise: frame0: regs=r6 stack= before 8: (bf) r1 = r7") __msg("mark_precise: frame0: regs=r6 stack= before 7: (27) r6 *= 4") __msg("mark_precise: frame0: regs=r6 stack= before 6: (79) r6 = *(u64 *)(r10 -8)") -__msg("mark_precise: frame0: parent state regs= stack=-8:") -__msg("mark_precise: frame0: last_idx 5 first_idx 0") __msg("mark_precise: frame0: regs= stack=-8 before 5: (85) call pc+6") __msg("mark_precise: frame0: regs= stack=-8 before 4: (b7) r1 = 0") __msg("mark_precise: frame0: regs= stack=-8 before 3: (7b) *(u64 *)(r10 -8) = r6") -- cgit v1.2.3 From 75a442581d05edaee168222ffbe00d4389785636 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Sat, 11 Nov 2023 12:38:21 +0800 Subject: bpf: Add missed allocation hint for bpf_mem_cache_alloc_flags() bpf_mem_cache_alloc_flags() may call __alloc() directly when there is no free object in free list, but it doesn't initialize the allocation hint for the returned pointer. It may lead to bad memory dereference when freeing the pointer, so fix it by initializing the allocation hint. Fixes: 822fb26bdb55 ("bpf: Add a hint to allocated objects.") Signed-off-by: Hou Tao Acked-by: Yonghong Song Link: https://lore.kernel.org/r/20231111043821.2258513-1-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/memalloc.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index 63b909d277d4..6a51cfe4c2d6 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -978,6 +978,8 @@ void notrace *bpf_mem_cache_alloc_flags(struct bpf_mem_alloc *ma, gfp_t flags) memcg = get_memcg(c); old_memcg = set_active_memcg(memcg); ret = __alloc(c, NUMA_NO_NODE, GFP_KERNEL | __GFP_NOWARN | __GFP_ACCOUNT); + if (ret) + *(struct bpf_mem_cache **)ret = c; set_active_memcg(old_memcg); mem_cgroup_put(memcg); } -- cgit v1.2.3 From dfce9cb3140592b886838e06f3e0c25fea2a9cae Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Thu, 30 Nov 2023 18:46:40 -0800 Subject: bpf: Fix a verifier bug due to incorrect branch offset comparison with cpu=v4 Bpf cpu=v4 support is introduced in [1] and Commit 4cd58e9af8b9 ("bpf: Support new 32bit offset jmp instruction") added support for new 32bit offset jmp instruction. Unfortunately, in function bpf_adj_delta_to_off(), for new branch insn with 32bit offset, the offset (plus/minor a small delta) compares to 16-bit offset bound [S16_MIN, S16_MAX], which caused the following verification failure: $ ./test_progs-cpuv4 -t verif_scale_pyperf180 ... insn 10 cannot be patched due to 16-bit range ... libbpf: failed to load object 'pyperf180.bpf.o' scale_test:FAIL:expect_success unexpected error: -12 (errno 12) #405 verif_scale_pyperf180:FAIL Note that due to recent llvm18 development, the patch [2] (already applied in bpf-next) needs to be applied to bpf tree for testing purpose. The fix is rather simple. For 32bit offset branch insn, the adjusted offset compares to [S32_MIN, S32_MAX] and then verification succeeded. [1] https://lore.kernel.org/all/20230728011143.3710005-1-yonghong.song@linux.dev [2] https://lore.kernel.org/bpf/20231110193644.3130906-1-yonghong.song@linux.dev Fixes: 4cd58e9af8b9 ("bpf: Support new 32bit offset jmp instruction") Signed-off-by: Yonghong Song Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20231201024640.3417057-1-yonghong.song@linux.dev --- kernel/bpf/core.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index cd3afe57ece3..fe254ae035fe 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -371,14 +371,18 @@ static int bpf_adj_delta_to_imm(struct bpf_insn *insn, u32 pos, s32 end_old, static int bpf_adj_delta_to_off(struct bpf_insn *insn, u32 pos, s32 end_old, s32 end_new, s32 curr, const bool probe_pass) { - const s32 off_min = S16_MIN, off_max = S16_MAX; + s64 off_min, off_max, off; s32 delta = end_new - end_old; - s32 off; - if (insn->code == (BPF_JMP32 | BPF_JA)) + if (insn->code == (BPF_JMP32 | BPF_JA)) { off = insn->imm; - else + off_min = S32_MIN; + off_max = S32_MAX; + } else { off = insn->off; + off_min = S16_MIN; + off_max = S16_MAX; + } if (curr < pos && curr + off + 1 >= end_old) off += delta; -- cgit v1.2.3 From 5fad52bee30414270104525e3a0266327a6e9d11 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sat, 2 Dec 2023 09:56:56 -0800 Subject: bpf: provide correct register name for exception callback retval check bpf_throw() is checking R1, so let's report R1 in the log. Acked-by: Eduard Zingerman Acked-by: Shung-Hsi Yu Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231202175705.885270-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 12 ++++++------ tools/testing/selftests/bpf/progs/exceptions_assert.c | 2 +- tools/testing/selftests/bpf/progs/exceptions_fail.c | 2 +- 3 files changed, 8 insertions(+), 8 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 8e7b6072e3f4..25b9d470957e 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -11805,7 +11805,7 @@ static int fetch_kfunc_meta(struct bpf_verifier_env *env, return 0; } -static int check_return_code(struct bpf_verifier_env *env, int regno); +static int check_return_code(struct bpf_verifier_env *env, int regno, const char *reg_name); static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, int *insn_idx_p) @@ -11942,7 +11942,7 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, * to bpf_throw becomes the return value of the program. */ if (!env->exception_callback_subprog) { - err = check_return_code(env, BPF_REG_1); + err = check_return_code(env, BPF_REG_1, "R1"); if (err < 0) return err; } @@ -14972,7 +14972,7 @@ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) return 0; } -static int check_return_code(struct bpf_verifier_env *env, int regno) +static int check_return_code(struct bpf_verifier_env *env, int regno, const char *reg_name) { struct tnum enforce_attach_type_range = tnum_unknown; const struct bpf_prog *prog = env->prog; @@ -15026,7 +15026,7 @@ static int check_return_code(struct bpf_verifier_env *env, int regno) } if (!tnum_in(const_0, reg->var_off)) { - verbose_invalid_scalar(env, reg, &const_0, "async callback", "R0"); + verbose_invalid_scalar(env, reg, &const_0, "async callback", reg_name); return -EINVAL; } return 0; @@ -15126,7 +15126,7 @@ static int check_return_code(struct bpf_verifier_env *env, int regno) } if (!tnum_in(range, reg->var_off)) { - verbose_invalid_scalar(env, reg, &range, "program exit", "R0"); + verbose_invalid_scalar(env, reg, &range, "program exit", reg_name); if (prog->expected_attach_type == BPF_LSM_CGROUP && prog_type == BPF_PROG_TYPE_LSM && !prog->aux->attach_func_proto->type) @@ -17410,7 +17410,7 @@ process_bpf_exit_full: continue; } - err = check_return_code(env, BPF_REG_0); + err = check_return_code(env, BPF_REG_0, "R0"); if (err) return err; process_bpf_exit: diff --git a/tools/testing/selftests/bpf/progs/exceptions_assert.c b/tools/testing/selftests/bpf/progs/exceptions_assert.c index 49efaed143fc..575e7dd719c4 100644 --- a/tools/testing/selftests/bpf/progs/exceptions_assert.c +++ b/tools/testing/selftests/bpf/progs/exceptions_assert.c @@ -125,7 +125,7 @@ int check_assert_generic(struct __sk_buff *ctx) } SEC("?fentry/bpf_check") -__failure __msg("At program exit the register R0 has value (0x40; 0x0)") +__failure __msg("At program exit the register R1 has value (0x40; 0x0)") int check_assert_with_return(void *ctx) { bpf_assert_with(!ctx, 64); diff --git a/tools/testing/selftests/bpf/progs/exceptions_fail.c b/tools/testing/selftests/bpf/progs/exceptions_fail.c index 8c0ef2742208..81ead7512ba2 100644 --- a/tools/testing/selftests/bpf/progs/exceptions_fail.c +++ b/tools/testing/selftests/bpf/progs/exceptions_fail.c @@ -308,7 +308,7 @@ int reject_set_exception_cb_bad_ret1(void *ctx) } SEC("?fentry/bpf_check") -__failure __msg("At program exit the register R0 has value (0x40; 0x0) should") +__failure __msg("At program exit the register R1 has value (0x40; 0x0) should") int reject_set_exception_cb_bad_ret2(void *ctx) { bpf_throw(64); -- cgit v1.2.3 From 0acd03a5bd188b0c501d285d938439618bd855c4 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sat, 2 Dec 2023 09:56:57 -0800 Subject: bpf: enforce precision of R0 on callback return Given verifier checks actual value, r0 has to be precise, so we need to propagate precision properly. r0 also has to be marked as read, otherwise subsequent state comparisons will ignore such register as unimportant and precision won't really help here. Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper") Acked-by: Eduard Zingerman Acked-by: Shung-Hsi Yu Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231202175705.885270-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 25b9d470957e..849fbf47b5f3 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9590,6 +9590,13 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) verbose(env, "R0 not a scalar value\n"); return -EACCES; } + + /* we are going to rely on register's precise value */ + err = mark_reg_read(env, r0, r0->parent, REG_LIVE_READ64); + err = err ?: mark_chain_precision(env, BPF_REG_0); + if (err) + return err; + if (!tnum_in(range, r0->var_off)) { verbose_invalid_scalar(env, r0, &range, "callback return", "R0"); return -EINVAL; -- cgit v1.2.3 From 8fa4ecd49b81ccd9d1d87f1c8b2260e218644878 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sat, 2 Dec 2023 09:56:58 -0800 Subject: bpf: enforce exact retval range on subprog/callback exit Instead of relying on potentially imprecise tnum representation of expected return value range for callbacks and subprogs, validate that smin/smax range satisfy exact expected range of return values. E.g., if callback would need to return [0, 2] range, tnum can't represent this precisely and instead will allow [0, 3] range. By checking smin/smax range, we can make sure that subprog/callback indeed returns only valid [0, 2] range. Acked-by: Eduard Zingerman Acked-by: Shung-Hsi Yu Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231202175705.885270-5-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf_verifier.h | 7 ++++++- kernel/bpf/verifier.c | 33 ++++++++++++++++++++++----------- 2 files changed, 28 insertions(+), 12 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 0c0e1bccad45..3378cc753061 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -275,6 +275,11 @@ struct bpf_reference_state { int callback_ref; }; +struct bpf_retval_range { + s32 minval; + s32 maxval; +}; + /* state of the program: * type of all registers and stack info */ @@ -297,7 +302,7 @@ struct bpf_func_state { * void foo(void) { bpf_timer_set_callback(,foo); } */ u32 async_entry_cnt; - struct tnum callback_ret_range; + struct bpf_retval_range callback_ret_range; bool in_callback_fn; bool in_async_callback_fn; bool in_exception_callback_fn; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 849fbf47b5f3..f3d9d7de68da 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2305,6 +2305,11 @@ static void init_reg_state(struct bpf_verifier_env *env, regs[BPF_REG_FP].frameno = state->frameno; } +static struct bpf_retval_range retval_range(s32 minval, s32 maxval) +{ + return (struct bpf_retval_range){ minval, maxval }; +} + #define BPF_MAIN_FUNC (-1) static void init_func_state(struct bpf_verifier_env *env, struct bpf_func_state *state, @@ -2313,7 +2318,7 @@ static void init_func_state(struct bpf_verifier_env *env, state->callsite = callsite; state->frameno = frameno; state->subprogno = subprogno; - state->callback_ret_range = tnum_range(0, 0); + state->callback_ret_range = retval_range(0, 0); init_reg_state(env, state); mark_verifier_state_scratched(env); } @@ -9396,7 +9401,7 @@ static int set_map_elem_callback_state(struct bpf_verifier_env *env, return err; callee->in_callback_fn = true; - callee->callback_ret_range = tnum_range(0, 1); + callee->callback_ret_range = retval_range(0, 1); return 0; } @@ -9418,7 +9423,7 @@ static int set_loop_callback_state(struct bpf_verifier_env *env, __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); callee->in_callback_fn = true; - callee->callback_ret_range = tnum_range(0, 1); + callee->callback_ret_range = retval_range(0, 1); return 0; } @@ -9448,7 +9453,7 @@ static int set_timer_callback_state(struct bpf_verifier_env *env, __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); callee->in_async_callback_fn = true; - callee->callback_ret_range = tnum_range(0, 1); + callee->callback_ret_range = retval_range(0, 1); return 0; } @@ -9476,7 +9481,7 @@ static int set_find_vma_callback_state(struct bpf_verifier_env *env, __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); callee->in_callback_fn = true; - callee->callback_ret_range = tnum_range(0, 1); + callee->callback_ret_range = retval_range(0, 1); return 0; } @@ -9499,7 +9504,7 @@ static int set_user_ringbuf_callback_state(struct bpf_verifier_env *env, __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); callee->in_callback_fn = true; - callee->callback_ret_range = tnum_range(0, 1); + callee->callback_ret_range = retval_range(0, 1); return 0; } @@ -9531,7 +9536,7 @@ static int set_rbtree_add_callback_state(struct bpf_verifier_env *env, __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); callee->in_callback_fn = true; - callee->callback_ret_range = tnum_range(0, 1); + callee->callback_ret_range = retval_range(0, 1); return 0; } @@ -9560,6 +9565,11 @@ static bool in_rbtree_lock_required_cb(struct bpf_verifier_env *env) return is_rbtree_lock_required_kfunc(kfunc_btf_id); } +static bool retval_range_within(struct bpf_retval_range range, const struct bpf_reg_state *reg) +{ + return range.minval <= reg->smin_value && reg->smax_value <= range.maxval; +} + static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) { struct bpf_verifier_state *state = env->cur_state, *prev_st; @@ -9583,9 +9593,6 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) caller = state->frame[state->curframe - 1]; if (callee->in_callback_fn) { - /* enforce R0 return value range [0, 1]. */ - struct tnum range = callee->callback_ret_range; - if (r0->type != SCALAR_VALUE) { verbose(env, "R0 not a scalar value\n"); return -EACCES; @@ -9597,7 +9604,11 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) if (err) return err; - if (!tnum_in(range, r0->var_off)) { + /* enforce R0 return value range */ + if (!retval_range_within(callee->callback_ret_range, r0)) { + struct tnum range = tnum_range(callee->callback_ret_range.minval, + callee->callback_ret_range.maxval); + verbose_invalid_scalar(env, r0, &range, "callback return", "R0"); return -EINVAL; } -- cgit v1.2.3 From c871d0e00f0e8c207ce8ff89025e35cc49a8a3c3 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sat, 2 Dec 2023 09:57:00 -0800 Subject: bpf: enforce precise retval range on program exit Similarly to subprog/callback logic, enforce return value of BPF program using more precise smin/smax range. We need to adjust a bunch of tests due to a changed format of an error message. Acked-by: Eduard Zingerman Acked-by: Shung-Hsi Yu Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231202175705.885270-7-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 56 +++++++++++----------- .../selftests/bpf/progs/exceptions_assert.c | 2 +- .../testing/selftests/bpf/progs/exceptions_fail.c | 2 +- .../selftests/bpf/progs/test_global_func15.c | 2 +- tools/testing/selftests/bpf/progs/timer_failure.c | 2 +- .../selftests/bpf/progs/user_ringbuf_fail.c | 2 +- .../bpf/progs/verifier_cgroup_inv_retcode.c | 8 ++-- .../bpf/progs/verifier_netfilter_retcode.c | 2 +- .../bpf/progs/verifier_subprog_precision.c | 2 +- 9 files changed, 40 insertions(+), 38 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f3d9d7de68da..9411c1046268 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -362,20 +362,23 @@ __printf(2, 3) static void verbose(void *private_data, const char *fmt, ...) static void verbose_invalid_scalar(struct bpf_verifier_env *env, struct bpf_reg_state *reg, - struct tnum *range, const char *ctx, + struct bpf_retval_range range, const char *ctx, const char *reg_name) { - char tn_buf[48]; + bool unknown = true; - verbose(env, "At %s the register %s ", ctx, reg_name); - if (!tnum_is_unknown(reg->var_off)) { - tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); - verbose(env, "has value %s", tn_buf); - } else { - verbose(env, "has unknown scalar value"); + verbose(env, "At %s the register %s has", ctx, reg_name); + if (reg->smin_value > S64_MIN) { + verbose(env, " smin=%lld", reg->smin_value); + unknown = false; } - tnum_strn(tn_buf, sizeof(tn_buf), *range); - verbose(env, " should have been in %s\n", tn_buf); + if (reg->smax_value < S64_MAX) { + verbose(env, " smax=%lld", reg->smax_value); + unknown = false; + } + if (unknown) + verbose(env, " unknown scalar value"); + verbose(env, " should have been in [%d, %d]\n", range.minval, range.maxval); } static bool type_may_be_null(u32 type) @@ -9606,10 +9609,8 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) /* enforce R0 return value range */ if (!retval_range_within(callee->callback_ret_range, r0)) { - struct tnum range = tnum_range(callee->callback_ret_range.minval, - callee->callback_ret_range.maxval); - - verbose_invalid_scalar(env, r0, &range, "callback return", "R0"); + verbose_invalid_scalar(env, r0, callee->callback_ret_range, + "callback return", "R0"); return -EINVAL; } if (!calls_callback(env, callee->callsite)) { @@ -14995,7 +14996,8 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char struct tnum enforce_attach_type_range = tnum_unknown; const struct bpf_prog *prog = env->prog; struct bpf_reg_state *reg; - struct tnum range = tnum_range(0, 1), const_0 = tnum_const(0); + struct bpf_retval_range range = retval_range(0, 1); + struct bpf_retval_range const_0 = retval_range(0, 0); enum bpf_prog_type prog_type = resolve_prog_type(env->prog); int err; struct bpf_func_state *frame = env->cur_state->frame[0]; @@ -15043,8 +15045,8 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char return -EINVAL; } - if (!tnum_in(const_0, reg->var_off)) { - verbose_invalid_scalar(env, reg, &const_0, "async callback", reg_name); + if (!retval_range_within(const_0, reg)) { + verbose_invalid_scalar(env, reg, const_0, "async callback", reg_name); return -EINVAL; } return 0; @@ -15070,14 +15072,14 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char env->prog->expected_attach_type == BPF_CGROUP_INET4_GETSOCKNAME || env->prog->expected_attach_type == BPF_CGROUP_INET6_GETSOCKNAME || env->prog->expected_attach_type == BPF_CGROUP_UNIX_GETSOCKNAME) - range = tnum_range(1, 1); + range = retval_range(1, 1); if (env->prog->expected_attach_type == BPF_CGROUP_INET4_BIND || env->prog->expected_attach_type == BPF_CGROUP_INET6_BIND) - range = tnum_range(0, 3); + range = retval_range(0, 3); break; case BPF_PROG_TYPE_CGROUP_SKB: if (env->prog->expected_attach_type == BPF_CGROUP_INET_EGRESS) { - range = tnum_range(0, 3); + range = retval_range(0, 3); enforce_attach_type_range = tnum_range(2, 3); } break; @@ -15090,13 +15092,13 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char case BPF_PROG_TYPE_RAW_TRACEPOINT: if (!env->prog->aux->attach_btf_id) return 0; - range = tnum_const(0); + range = retval_range(0, 0); break; case BPF_PROG_TYPE_TRACING: switch (env->prog->expected_attach_type) { case BPF_TRACE_FENTRY: case BPF_TRACE_FEXIT: - range = tnum_const(0); + range = retval_range(0, 0); break; case BPF_TRACE_RAW_TP: case BPF_MODIFY_RETURN: @@ -15108,7 +15110,7 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char } break; case BPF_PROG_TYPE_SK_LOOKUP: - range = tnum_range(SK_DROP, SK_PASS); + range = retval_range(SK_DROP, SK_PASS); break; case BPF_PROG_TYPE_LSM: @@ -15122,12 +15124,12 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char /* Make sure programs that attach to void * hooks don't try to modify return value. */ - range = tnum_range(1, 1); + range = retval_range(1, 1); } break; case BPF_PROG_TYPE_NETFILTER: - range = tnum_range(NF_DROP, NF_ACCEPT); + range = retval_range(NF_DROP, NF_ACCEPT); break; case BPF_PROG_TYPE_EXT: /* freplace program can return anything as its return value @@ -15143,8 +15145,8 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char return -EINVAL; } - if (!tnum_in(range, reg->var_off)) { - verbose_invalid_scalar(env, reg, &range, "program exit", reg_name); + if (!retval_range_within(range, reg)) { + verbose_invalid_scalar(env, reg, range, "program exit", reg_name); if (prog->expected_attach_type == BPF_LSM_CGROUP && prog_type == BPF_PROG_TYPE_LSM && !prog->aux->attach_func_proto->type) diff --git a/tools/testing/selftests/bpf/progs/exceptions_assert.c b/tools/testing/selftests/bpf/progs/exceptions_assert.c index 575e7dd719c4..0ef81040da59 100644 --- a/tools/testing/selftests/bpf/progs/exceptions_assert.c +++ b/tools/testing/selftests/bpf/progs/exceptions_assert.c @@ -125,7 +125,7 @@ int check_assert_generic(struct __sk_buff *ctx) } SEC("?fentry/bpf_check") -__failure __msg("At program exit the register R1 has value (0x40; 0x0)") +__failure __msg("At program exit the register R1 has smin=64 smax=64") int check_assert_with_return(void *ctx) { bpf_assert_with(!ctx, 64); diff --git a/tools/testing/selftests/bpf/progs/exceptions_fail.c b/tools/testing/selftests/bpf/progs/exceptions_fail.c index 81ead7512ba2..9cceb6521143 100644 --- a/tools/testing/selftests/bpf/progs/exceptions_fail.c +++ b/tools/testing/selftests/bpf/progs/exceptions_fail.c @@ -308,7 +308,7 @@ int reject_set_exception_cb_bad_ret1(void *ctx) } SEC("?fentry/bpf_check") -__failure __msg("At program exit the register R1 has value (0x40; 0x0) should") +__failure __msg("At program exit the register R1 has smin=64 smax=64 should") int reject_set_exception_cb_bad_ret2(void *ctx) { bpf_throw(64); diff --git a/tools/testing/selftests/bpf/progs/test_global_func15.c b/tools/testing/selftests/bpf/progs/test_global_func15.c index b512d6a6c75e..f80207480e8a 100644 --- a/tools/testing/selftests/bpf/progs/test_global_func15.c +++ b/tools/testing/selftests/bpf/progs/test_global_func15.c @@ -13,7 +13,7 @@ __noinline int foo(unsigned int *v) } SEC("cgroup_skb/ingress") -__failure __msg("At program exit the register R0 has value") +__failure __msg("At program exit the register R0 has ") int global_func15(struct __sk_buff *skb) { unsigned int v = 1; diff --git a/tools/testing/selftests/bpf/progs/timer_failure.c b/tools/testing/selftests/bpf/progs/timer_failure.c index 226d33b5a05c..9000da1e2120 100644 --- a/tools/testing/selftests/bpf/progs/timer_failure.c +++ b/tools/testing/selftests/bpf/progs/timer_failure.c @@ -30,7 +30,7 @@ static int timer_cb_ret1(void *map, int *key, struct bpf_timer *timer) } SEC("fentry/bpf_fentry_test1") -__failure __msg("should have been in (0x0; 0x0)") +__failure __msg("should have been in [0, 0]") int BPF_PROG2(test_ret_1, int, a) { int key = 0; diff --git a/tools/testing/selftests/bpf/progs/user_ringbuf_fail.c b/tools/testing/selftests/bpf/progs/user_ringbuf_fail.c index 03ee946c6bf7..11ab25c42c36 100644 --- a/tools/testing/selftests/bpf/progs/user_ringbuf_fail.c +++ b/tools/testing/selftests/bpf/progs/user_ringbuf_fail.c @@ -184,7 +184,7 @@ invalid_drain_callback_return(struct bpf_dynptr *dynptr, void *context) * not be able to write to that pointer. */ SEC("?raw_tp") -__failure __msg("At callback return the register R0 has value") +__failure __msg("At callback return the register R0 has ") int user_ringbuf_callback_invalid_return(void *ctx) { bpf_user_ringbuf_drain(&user_ringbuf, invalid_drain_callback_return, NULL, 0); diff --git a/tools/testing/selftests/bpf/progs/verifier_cgroup_inv_retcode.c b/tools/testing/selftests/bpf/progs/verifier_cgroup_inv_retcode.c index d6c4a7f3f790..6e0f349f8f15 100644 --- a/tools/testing/selftests/bpf/progs/verifier_cgroup_inv_retcode.c +++ b/tools/testing/selftests/bpf/progs/verifier_cgroup_inv_retcode.c @@ -7,7 +7,7 @@ SEC("cgroup/sock") __description("bpf_exit with invalid return code. test1") -__failure __msg("R0 has value (0x0; 0xffffffff)") +__failure __msg("smin=0 smax=4294967295 should have been in [0, 1]") __naked void with_invalid_return_code_test1(void) { asm volatile (" \ @@ -30,7 +30,7 @@ __naked void with_invalid_return_code_test2(void) SEC("cgroup/sock") __description("bpf_exit with invalid return code. test3") -__failure __msg("R0 has value (0x0; 0x3)") +__failure __msg("smin=0 smax=3 should have been in [0, 1]") __naked void with_invalid_return_code_test3(void) { asm volatile (" \ @@ -53,7 +53,7 @@ __naked void with_invalid_return_code_test4(void) SEC("cgroup/sock") __description("bpf_exit with invalid return code. test5") -__failure __msg("R0 has value (0x2; 0x0)") +__failure __msg("smin=2 smax=2 should have been in [0, 1]") __naked void with_invalid_return_code_test5(void) { asm volatile (" \ @@ -75,7 +75,7 @@ __naked void with_invalid_return_code_test6(void) SEC("cgroup/sock") __description("bpf_exit with invalid return code. test7") -__failure __msg("R0 has unknown scalar value") +__failure __msg("R0 has unknown scalar value should have been in [0, 1]") __naked void with_invalid_return_code_test7(void) { asm volatile (" \ diff --git a/tools/testing/selftests/bpf/progs/verifier_netfilter_retcode.c b/tools/testing/selftests/bpf/progs/verifier_netfilter_retcode.c index 353ae6da00e1..e1ffa5d32ff0 100644 --- a/tools/testing/selftests/bpf/progs/verifier_netfilter_retcode.c +++ b/tools/testing/selftests/bpf/progs/verifier_netfilter_retcode.c @@ -39,7 +39,7 @@ __naked void with_valid_return_code_test3(void) SEC("netfilter") __description("bpf_exit with invalid return code. test4") -__failure __msg("R0 has value (0x2; 0x0)") +__failure __msg("R0 has smin=2 smax=2 should have been in [0, 1]") __naked void with_invalid_return_code_test4(void) { asm volatile (" \ diff --git a/tools/testing/selftests/bpf/progs/verifier_subprog_precision.c b/tools/testing/selftests/bpf/progs/verifier_subprog_precision.c index d41d2a8bb97e..0dfe3f8b69ac 100644 --- a/tools/testing/selftests/bpf/progs/verifier_subprog_precision.c +++ b/tools/testing/selftests/bpf/progs/verifier_subprog_precision.c @@ -148,7 +148,7 @@ __msg("mark_precise: frame1: regs=r0 stack= before 11: (b7) r0 = 0") __msg("from 10 to 12: frame1: R0=scalar(smin=umin=1001") /* check that branch code path marks r0 as precise, before failing */ __msg("mark_precise: frame1: regs=r0 stack= before 9: (85) call bpf_get_prandom_u32#7") -__msg("At callback return the register R0 has value (0x0; 0x7fffffffffffffff) should have been in (0x0; 0x1)") +__msg("At callback return the register R0 has smin=1001 should have been in [0, 1]") __naked int callback_precise_return_fail(void) { asm volatile ( -- cgit v1.2.3 From 0ef24c8dfae24a4b8aa2e92eac20faecdc5502e5 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sat, 2 Dec 2023 09:57:01 -0800 Subject: bpf: unify async callback and program retval checks Use common logic to verify program return values and async callback return values. This allows to avoid duplication of any extra steps necessary, like precision marking, which will be added in the next patch. Acked-by: Eduard Zingerman Acked-by: Shung-Hsi Yu Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231202175705.885270-8-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 30 ++++++++++++------------------ 1 file changed, 12 insertions(+), 18 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9411c1046268..c54944af1bcc 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -367,7 +367,7 @@ static void verbose_invalid_scalar(struct bpf_verifier_env *env, { bool unknown = true; - verbose(env, "At %s the register %s has", ctx, reg_name); + verbose(env, "%s the register %s has", ctx, reg_name); if (reg->smin_value > S64_MIN) { verbose(env, " smin=%lld", reg->smin_value); unknown = false; @@ -9610,7 +9610,7 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) /* enforce R0 return value range */ if (!retval_range_within(callee->callback_ret_range, r0)) { verbose_invalid_scalar(env, r0, callee->callback_ret_range, - "callback return", "R0"); + "At callback return", "R0"); return -EINVAL; } if (!calls_callback(env, callee->callsite)) { @@ -14993,11 +14993,11 @@ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) static int check_return_code(struct bpf_verifier_env *env, int regno, const char *reg_name) { + const char *exit_ctx = "At program exit"; struct tnum enforce_attach_type_range = tnum_unknown; const struct bpf_prog *prog = env->prog; struct bpf_reg_state *reg; struct bpf_retval_range range = retval_range(0, 1); - struct bpf_retval_range const_0 = retval_range(0, 0); enum bpf_prog_type prog_type = resolve_prog_type(env->prog); int err; struct bpf_func_state *frame = env->cur_state->frame[0]; @@ -15039,17 +15039,9 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char if (frame->in_async_callback_fn) { /* enforce return zero from async callbacks like timer */ - if (reg->type != SCALAR_VALUE) { - verbose(env, "In async callback the register R%d is not a known value (%s)\n", - regno, reg_type_str(env, reg->type)); - return -EINVAL; - } - - if (!retval_range_within(const_0, reg)) { - verbose_invalid_scalar(env, reg, const_0, "async callback", reg_name); - return -EINVAL; - } - return 0; + exit_ctx = "At async callback return"; + range = retval_range(0, 0); + goto enforce_retval; } if (is_subprog && !frame->in_exception_callback_fn) { @@ -15139,15 +15131,17 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char return 0; } +enforce_retval: if (reg->type != SCALAR_VALUE) { - verbose(env, "At program exit the register R%d is not a known value (%s)\n", - regno, reg_type_str(env, reg->type)); + verbose(env, "%s the register R%d is not a known value (%s)\n", + exit_ctx, regno, reg_type_str(env, reg->type)); return -EINVAL; } if (!retval_range_within(range, reg)) { - verbose_invalid_scalar(env, reg, range, "program exit", reg_name); - if (prog->expected_attach_type == BPF_LSM_CGROUP && + verbose_invalid_scalar(env, reg, range, exit_ctx, reg_name); + if (!is_subprog && + prog->expected_attach_type == BPF_LSM_CGROUP && prog_type == BPF_PROG_TYPE_LSM && !prog->aux->attach_func_proto->type) verbose(env, "Note, BPF_LSM_CGROUP that attach to void LSM hooks can't modify return value!\n"); -- cgit v1.2.3 From eabe518de533a4291996020977054a7a7b78c7d3 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sat, 2 Dec 2023 09:57:02 -0800 Subject: bpf: enforce precision of R0 on program/async callback return Given we enforce a valid range for program and async callback return value, we must mark R0 as precise to avoid incorrect state pruning. Fixes: b5dc0163d8fd ("bpf: precise scalar_value tracking") Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231202175705.885270-9-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index c54944af1bcc..2cd150d6d141 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -15138,6 +15138,10 @@ enforce_retval: return -EINVAL; } + err = mark_chain_precision(env, regno); + if (err) + return err; + if (!retval_range_within(range, reg)) { verbose_invalid_scalar(env, reg, range, exit_ctx, reg_name); if (!is_subprog && -- cgit v1.2.3 From 81eff2e36481c5cf4a2ac906ae56c3fbd3e6f305 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sat, 2 Dec 2023 09:57:05 -0800 Subject: bpf: simplify tnum output if a fully known constant Emit tnum representation as just a constant if all bits are known. Use decimal-vs-hex logic to determine exact format of emitted constant value, just like it's done for register range values. For that move tnum_strn() to kernel/bpf/log.c to reuse decimal-vs-hex determination logic and constants. Acked-by: Shung-Hsi Yu Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231202175705.885270-12-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/log.c | 13 +++++++++++++ kernel/bpf/tnum.c | 6 ------ .../selftests/bpf/progs/verifier_direct_packet_access.c | 2 +- tools/testing/selftests/bpf/progs/verifier_int_ptr.c | 2 +- tools/testing/selftests/bpf/progs/verifier_stack_ptr.c | 4 ++-- 5 files changed, 17 insertions(+), 10 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c index 3505f3e5ae96..55d019f30e91 100644 --- a/kernel/bpf/log.c +++ b/kernel/bpf/log.c @@ -539,6 +539,19 @@ static void verbose_snum(struct bpf_verifier_env *env, s64 num) verbose(env, "%#llx", num); } +int tnum_strn(char *str, size_t size, struct tnum a) +{ + /* print as a constant, if tnum is fully known */ + if (a.mask == 0) { + if (is_unum_decimal(a.value)) + return snprintf(str, size, "%llu", a.value); + else + return snprintf(str, size, "%#llx", a.value); + } + return snprintf(str, size, "(%#llx; %#llx)", a.value, a.mask); +} +EXPORT_SYMBOL_GPL(tnum_strn); + static void print_scalar_ranges(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, const char **sep) diff --git a/kernel/bpf/tnum.c b/kernel/bpf/tnum.c index f4c91c9b27d7..9dbc31b25e3d 100644 --- a/kernel/bpf/tnum.c +++ b/kernel/bpf/tnum.c @@ -172,12 +172,6 @@ bool tnum_in(struct tnum a, struct tnum b) return a.value == b.value; } -int tnum_strn(char *str, size_t size, struct tnum a) -{ - return snprintf(str, size, "(%#llx; %#llx)", a.value, a.mask); -} -EXPORT_SYMBOL_GPL(tnum_strn); - int tnum_sbin(char *str, size_t size, struct tnum a) { size_t n; diff --git a/tools/testing/selftests/bpf/progs/verifier_direct_packet_access.c b/tools/testing/selftests/bpf/progs/verifier_direct_packet_access.c index 99a23dea8233..be95570ab382 100644 --- a/tools/testing/selftests/bpf/progs/verifier_direct_packet_access.c +++ b/tools/testing/selftests/bpf/progs/verifier_direct_packet_access.c @@ -411,7 +411,7 @@ l0_%=: r0 = 0; \ SEC("tc") __description("direct packet access: test17 (pruning, alignment)") -__failure __msg("misaligned packet access off 2+(0x0; 0x0)+15+-4 size 4") +__failure __msg("misaligned packet access off 2+0+15+-4 size 4") __flag(BPF_F_STRICT_ALIGNMENT) __naked void packet_access_test17_pruning_alignment(void) { diff --git a/tools/testing/selftests/bpf/progs/verifier_int_ptr.c b/tools/testing/selftests/bpf/progs/verifier_int_ptr.c index b054f9c48143..74d9cad469d9 100644 --- a/tools/testing/selftests/bpf/progs/verifier_int_ptr.c +++ b/tools/testing/selftests/bpf/progs/verifier_int_ptr.c @@ -67,7 +67,7 @@ __naked void ptr_to_long_half_uninitialized(void) SEC("cgroup/sysctl") __description("ARG_PTR_TO_LONG misaligned") -__failure __msg("misaligned stack access off (0x0; 0x0)+-20+0 size 8") +__failure __msg("misaligned stack access off 0+-20+0 size 8") __naked void arg_ptr_to_long_misaligned(void) { asm volatile (" \ diff --git a/tools/testing/selftests/bpf/progs/verifier_stack_ptr.c b/tools/testing/selftests/bpf/progs/verifier_stack_ptr.c index e0f77e3e7869..417c61cd4b19 100644 --- a/tools/testing/selftests/bpf/progs/verifier_stack_ptr.c +++ b/tools/testing/selftests/bpf/progs/verifier_stack_ptr.c @@ -37,7 +37,7 @@ __naked void ptr_to_stack_store_load(void) SEC("socket") __description("PTR_TO_STACK store/load - bad alignment on off") -__failure __msg("misaligned stack access off (0x0; 0x0)+-8+2 size 8") +__failure __msg("misaligned stack access off 0+-8+2 size 8") __failure_unpriv __naked void load_bad_alignment_on_off(void) { @@ -53,7 +53,7 @@ __naked void load_bad_alignment_on_off(void) SEC("socket") __description("PTR_TO_STACK store/load - bad alignment on reg") -__failure __msg("misaligned stack access off (0x0; 0x0)+-10+8 size 8") +__failure __msg("misaligned stack access off 0+-10+8 size 8") __failure_unpriv __naked void load_bad_alignment_on_reg(void) { -- cgit v1.2.3 From 5bd90cdc65ef9ef5e13c9ff23620079db5c608a0 Mon Sep 17 00:00:00 2001 From: Andrei Matei Date: Sun, 3 Dec 2023 20:12:48 -0500 Subject: bpf: Minor logging improvement One place where we were logging a register was only logging the variable part, not also the fixed part. Signed-off-by: Andrei Matei Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20231204011248.2040084-1-andreimatei1@gmail.com --- kernel/bpf/verifier.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 2cd150d6d141..cdb4f5f0ba79 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6585,8 +6585,8 @@ static int check_stack_access_within_bounds( char tn_buf[48]; tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); - verbose(env, "invalid variable-offset%s stack R%d var_off=%s size=%d\n", - err_extra, regno, tn_buf, access_size); + verbose(env, "invalid variable-offset%s stack R%d var_off=%s off=%d size=%d\n", + err_extra, regno, tn_buf, off, access_size); } } return err; -- cgit v1.2.3 From 169410eba271afc9f0fb476d996795aa26770c6d Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Mon, 4 Dec 2023 22:04:19 +0800 Subject: bpf: Check rcu_read_lock_trace_held() before calling bpf map helpers These three bpf_map_{lookup,update,delete}_elem() helpers are also available for sleepable bpf program, so add the corresponding lock assertion for sleepable bpf program, otherwise the following warning will be reported when a sleepable bpf program manipulates bpf map under interpreter mode (aka bpf_jit_enable=0): WARNING: CPU: 3 PID: 4985 at kernel/bpf/helpers.c:40 ...... CPU: 3 PID: 4985 Comm: test_progs Not tainted 6.6.0+ #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) ...... RIP: 0010:bpf_map_lookup_elem+0x54/0x60 ...... Call Trace: ? __warn+0xa5/0x240 ? bpf_map_lookup_elem+0x54/0x60 ? report_bug+0x1ba/0x1f0 ? handle_bug+0x40/0x80 ? exc_invalid_op+0x18/0x50 ? asm_exc_invalid_op+0x1b/0x20 ? __pfx_bpf_map_lookup_elem+0x10/0x10 ? rcu_lockdep_current_cpu_online+0x65/0xb0 ? rcu_is_watching+0x23/0x50 ? bpf_map_lookup_elem+0x54/0x60 ? __pfx_bpf_map_lookup_elem+0x10/0x10 ___bpf_prog_run+0x513/0x3b70 __bpf_prog_run32+0x9d/0xd0 ? __bpf_prog_enter_sleepable_recur+0xad/0x120 ? __bpf_prog_enter_sleepable_recur+0x3e/0x120 bpf_trampoline_6442580665+0x4d/0x1000 __x64_sys_getpgid+0x5/0x30 ? do_syscall_64+0x36/0xb0 entry_SYSCALL_64_after_hwframe+0x6e/0x76 Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20231204140425.1480317-2-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/helpers.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index b45a8381f9bd..ee9bdf29246a 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -32,12 +32,13 @@ * * Different map implementations will rely on rcu in map methods * lookup/update/delete, therefore eBPF programs must run under rcu lock - * if program is allowed to access maps, so check rcu_read_lock_held in - * all three functions. + * if program is allowed to access maps, so check rcu_read_lock_held() or + * rcu_read_lock_trace_held() in all three functions. */ BPF_CALL_2(bpf_map_lookup_elem, struct bpf_map *, map, void *, key) { - WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_bh_held()); + WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() && + !rcu_read_lock_bh_held()); return (unsigned long) map->ops->map_lookup_elem(map, key); } @@ -53,7 +54,8 @@ const struct bpf_func_proto bpf_map_lookup_elem_proto = { BPF_CALL_4(bpf_map_update_elem, struct bpf_map *, map, void *, key, void *, value, u64, flags) { - WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_bh_held()); + WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() && + !rcu_read_lock_bh_held()); return map->ops->map_update_elem(map, key, value, flags); } @@ -70,7 +72,8 @@ const struct bpf_func_proto bpf_map_update_elem_proto = { BPF_CALL_2(bpf_map_delete_elem, struct bpf_map *, map, void *, key) { - WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_bh_held()); + WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() && + !rcu_read_lock_bh_held()); return map->ops->map_delete_elem(map, key); } -- cgit v1.2.3 From 20c20bd11a0702ce4dc9300c3da58acf551d9725 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Mon, 4 Dec 2023 22:04:20 +0800 Subject: bpf: Add map and need_defer parameters to .map_fd_put_ptr() map is the pointer of outer map, and need_defer needs some explanation. need_defer tells the implementation to defer the reference release of the passed element and ensure that the element is still alive before the bpf program, which may manipulate it, exits. The following three cases will invoke map_fd_put_ptr() and different need_defer values will be passed to these callers: 1) release the reference of the old element in the map during map update or map deletion. The release must be deferred, otherwise the bpf program may incur use-after-free problem, so need_defer needs to be true. 2) release the reference of the to-be-added element in the error path of map update. The to-be-added element is not visible to any bpf program, so it is OK to pass false for need_defer parameter. 3) release the references of all elements in the map during map release. Any bpf program which has access to the map must have been exited and released, so need_defer=false will be OK. These two parameters will be used by the following patches to fix the potential use-after-free problem for map-in-map. Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20231204140425.1480317-3-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 6 +++++- kernel/bpf/arraymap.c | 12 +++++++----- kernel/bpf/hashtab.c | 6 +++--- kernel/bpf/map_in_map.c | 2 +- kernel/bpf/map_in_map.h | 2 +- 5 files changed, 17 insertions(+), 11 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index eb447b0a9423..d273348cfb2f 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -106,7 +106,11 @@ struct bpf_map_ops { /* funcs called by prog_array and perf_event_array map */ void *(*map_fd_get_ptr)(struct bpf_map *map, struct file *map_file, int fd); - void (*map_fd_put_ptr)(void *ptr); + /* If need_defer is true, the implementation should guarantee that + * the to-be-put element is still alive before the bpf program, which + * may manipulate it, exists. + */ + void (*map_fd_put_ptr)(struct bpf_map *map, void *ptr, bool need_defer); int (*map_gen_lookup)(struct bpf_map *map, struct bpf_insn *insn_buf); u32 (*map_fd_sys_lookup_elem)(void *ptr); void (*map_seq_show_elem)(struct bpf_map *map, void *key, diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 2058e89b5ddd..f9aed5909d6e 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -867,7 +867,7 @@ int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file, } if (old_ptr) - map->ops->map_fd_put_ptr(old_ptr); + map->ops->map_fd_put_ptr(map, old_ptr, true); return 0; } @@ -890,7 +890,7 @@ static long fd_array_map_delete_elem(struct bpf_map *map, void *key) } if (old_ptr) { - map->ops->map_fd_put_ptr(old_ptr); + map->ops->map_fd_put_ptr(map, old_ptr, true); return 0; } else { return -ENOENT; @@ -913,8 +913,9 @@ static void *prog_fd_array_get_ptr(struct bpf_map *map, return prog; } -static void prog_fd_array_put_ptr(void *ptr) +static void prog_fd_array_put_ptr(struct bpf_map *map, void *ptr, bool need_defer) { + /* bpf_prog is freed after one RCU or tasks trace grace period */ bpf_prog_put(ptr); } @@ -1239,8 +1240,9 @@ err_out: return ee; } -static void perf_event_fd_array_put_ptr(void *ptr) +static void perf_event_fd_array_put_ptr(struct bpf_map *map, void *ptr, bool need_defer) { + /* bpf_perf_event is freed after one RCU grace period */ bpf_event_entry_free_rcu(ptr); } @@ -1294,7 +1296,7 @@ static void *cgroup_fd_array_get_ptr(struct bpf_map *map, return cgroup_get_from_fd(fd); } -static void cgroup_fd_array_put_ptr(void *ptr) +static void cgroup_fd_array_put_ptr(struct bpf_map *map, void *ptr, bool need_defer) { /* cgroup_put free cgrp after a rcu grace period */ cgroup_put(ptr); diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index fd8d4b0addfc..5b9146fa825f 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -897,7 +897,7 @@ static void htab_put_fd_value(struct bpf_htab *htab, struct htab_elem *l) if (map->ops->map_fd_put_ptr) { ptr = fd_htab_map_get_ptr(map, l); - map->ops->map_fd_put_ptr(ptr); + map->ops->map_fd_put_ptr(map, ptr, true); } } @@ -2484,7 +2484,7 @@ static void fd_htab_map_free(struct bpf_map *map) hlist_nulls_for_each_entry_safe(l, n, head, hash_node) { void *ptr = fd_htab_map_get_ptr(map, l); - map->ops->map_fd_put_ptr(ptr); + map->ops->map_fd_put_ptr(map, ptr, false); } } @@ -2525,7 +2525,7 @@ int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file, ret = htab_map_update_elem(map, key, &ptr, map_flags); if (ret) - map->ops->map_fd_put_ptr(ptr); + map->ops->map_fd_put_ptr(map, ptr, false); return ret; } diff --git a/kernel/bpf/map_in_map.c b/kernel/bpf/map_in_map.c index cd5eafaba97e..2dfeb5835e16 100644 --- a/kernel/bpf/map_in_map.c +++ b/kernel/bpf/map_in_map.c @@ -127,7 +127,7 @@ void *bpf_map_fd_get_ptr(struct bpf_map *map, return inner_map; } -void bpf_map_fd_put_ptr(void *ptr) +void bpf_map_fd_put_ptr(struct bpf_map *map, void *ptr, bool need_defer) { /* ptr->ops->map_free() has to go through one * rcu grace period by itself. diff --git a/kernel/bpf/map_in_map.h b/kernel/bpf/map_in_map.h index bcb7534afb3c..7d61602354de 100644 --- a/kernel/bpf/map_in_map.h +++ b/kernel/bpf/map_in_map.h @@ -13,7 +13,7 @@ struct bpf_map *bpf_map_meta_alloc(int inner_map_ufd); void bpf_map_meta_free(struct bpf_map *map_meta); void *bpf_map_fd_get_ptr(struct bpf_map *map, struct file *map_file, int ufd); -void bpf_map_fd_put_ptr(void *ptr); +void bpf_map_fd_put_ptr(struct bpf_map *map, void *ptr, bool need_defer); u32 bpf_map_fd_sys_lookup_elem(void *ptr); #endif -- cgit v1.2.3 From 79d93b3c6ffd79abcd8e43345980aa1e904879c4 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Mon, 4 Dec 2023 22:04:21 +0800 Subject: bpf: Set need_defer as false when clearing fd array during map free Both map deletion operation, map release and map free operation use fd_array_map_delete_elem() to remove the element from fd array and need_defer is always true in fd_array_map_delete_elem(). For the map deletion operation and map release operation, need_defer=true is necessary, because the bpf program, which accesses the element in fd array, may still alive. However for map free operation, it is certain that the bpf program which owns the fd array has already been exited, so setting need_defer as false is appropriate for map free operation. So fix it by adding need_defer parameter to bpf_fd_array_map_clear() and adding a new helper __fd_array_map_delete_elem() to handle the map deletion, map release and map free operations correspondingly. Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20231204140425.1480317-4-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/arraymap.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index f9aed5909d6e..4a4a67956e21 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -871,7 +871,7 @@ int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file, return 0; } -static long fd_array_map_delete_elem(struct bpf_map *map, void *key) +static long __fd_array_map_delete_elem(struct bpf_map *map, void *key, bool need_defer) { struct bpf_array *array = container_of(map, struct bpf_array, map); void *old_ptr; @@ -890,13 +890,18 @@ static long fd_array_map_delete_elem(struct bpf_map *map, void *key) } if (old_ptr) { - map->ops->map_fd_put_ptr(map, old_ptr, true); + map->ops->map_fd_put_ptr(map, old_ptr, need_defer); return 0; } else { return -ENOENT; } } +static long fd_array_map_delete_elem(struct bpf_map *map, void *key) +{ + return __fd_array_map_delete_elem(map, key, true); +} + static void *prog_fd_array_get_ptr(struct bpf_map *map, struct file *map_file, int fd) { @@ -925,13 +930,13 @@ static u32 prog_fd_array_sys_lookup_elem(void *ptr) } /* decrement refcnt of all bpf_progs that are stored in this map */ -static void bpf_fd_array_map_clear(struct bpf_map *map) +static void bpf_fd_array_map_clear(struct bpf_map *map, bool need_defer) { struct bpf_array *array = container_of(map, struct bpf_array, map); int i; for (i = 0; i < array->map.max_entries; i++) - fd_array_map_delete_elem(map, &i); + __fd_array_map_delete_elem(map, &i, need_defer); } static void prog_array_map_seq_show_elem(struct bpf_map *map, void *key, @@ -1110,7 +1115,7 @@ static void prog_array_map_clear_deferred(struct work_struct *work) { struct bpf_map *map = container_of(work, struct bpf_array_aux, work)->map; - bpf_fd_array_map_clear(map); + bpf_fd_array_map_clear(map, true); bpf_map_put(map); } @@ -1260,7 +1265,7 @@ static void perf_event_fd_array_release(struct bpf_map *map, for (i = 0; i < array->map.max_entries; i++) { ee = READ_ONCE(array->ptrs[i]); if (ee && ee->map_file == map_file) - fd_array_map_delete_elem(map, &i); + __fd_array_map_delete_elem(map, &i, true); } rcu_read_unlock(); } @@ -1268,7 +1273,7 @@ static void perf_event_fd_array_release(struct bpf_map *map, static void perf_event_fd_array_map_free(struct bpf_map *map) { if (map->map_flags & BPF_F_PRESERVE_ELEMS) - bpf_fd_array_map_clear(map); + bpf_fd_array_map_clear(map, false); fd_array_map_free(map); } @@ -1304,7 +1309,7 @@ static void cgroup_fd_array_put_ptr(struct bpf_map *map, void *ptr, bool need_de static void cgroup_fd_array_free(struct bpf_map *map) { - bpf_fd_array_map_clear(map); + bpf_fd_array_map_clear(map, false); fd_array_map_free(map); } @@ -1349,7 +1354,7 @@ static void array_of_map_free(struct bpf_map *map) * is protected by fdget/fdput. */ bpf_map_meta_free(map->inner_map_meta); - bpf_fd_array_map_clear(map); + bpf_fd_array_map_clear(map, false); fd_array_map_free(map); } -- cgit v1.2.3 From 876673364161da50eed6b472d746ef88242b2368 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Mon, 4 Dec 2023 22:04:22 +0800 Subject: bpf: Defer the free of inner map when necessary When updating or deleting an inner map in map array or map htab, the map may still be accessed by non-sleepable program or sleepable program. However bpf_map_fd_put_ptr() decreases the ref-counter of the inner map directly through bpf_map_put(), if the ref-counter is the last one (which is true for most cases), the inner map will be freed by ops->map_free() in a kworker. But for now, most .map_free() callbacks don't use synchronize_rcu() or its variants to wait for the elapse of a RCU grace period, so after the invocation of ops->map_free completes, the bpf program which is accessing the inner map may incur use-after-free problem. Fix the free of inner map by invoking bpf_map_free_deferred() after both one RCU grace period and one tasks trace RCU grace period if the inner map has been removed from the outer map before. The deferment is accomplished by using call_rcu() or call_rcu_tasks_trace() when releasing the last ref-counter of bpf map. The newly-added rcu_head field in bpf_map shares the same storage space with work field to reduce the size of bpf_map. Fixes: bba1dc0b55ac ("bpf: Remove redundant synchronize_rcu.") Fixes: 638e4b825d52 ("bpf: Allows per-cpu maps and map-in-map in sleepable programs") Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20231204140425.1480317-5-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 7 ++++++- kernel/bpf/map_in_map.c | 11 ++++++++--- kernel/bpf/syscall.c | 32 +++++++++++++++++++++++++++----- 3 files changed, 41 insertions(+), 9 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index d273348cfb2f..de3bd03cbeea 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -276,7 +276,11 @@ struct bpf_map { */ atomic64_t refcnt ____cacheline_aligned; atomic64_t usercnt; - struct work_struct work; + /* rcu is used before freeing and work is only used during freeing */ + union { + struct work_struct work; + struct rcu_head rcu; + }; struct mutex freeze_mutex; atomic64_t writecnt; /* 'Ownership' of program-containing map is claimed by the first program @@ -292,6 +296,7 @@ struct bpf_map { } owner; bool bypass_spec_v1; bool frozen; /* write-once; write-protected by freeze_mutex */ + bool free_after_mult_rcu_gp; s64 __percpu *elem_count; }; diff --git a/kernel/bpf/map_in_map.c b/kernel/bpf/map_in_map.c index 2dfeb5835e16..3248ff5d8161 100644 --- a/kernel/bpf/map_in_map.c +++ b/kernel/bpf/map_in_map.c @@ -129,10 +129,15 @@ void *bpf_map_fd_get_ptr(struct bpf_map *map, void bpf_map_fd_put_ptr(struct bpf_map *map, void *ptr, bool need_defer) { - /* ptr->ops->map_free() has to go through one - * rcu grace period by itself. + struct bpf_map *inner_map = ptr; + + /* The inner map may still be used by both non-sleepable and sleepable + * bpf program, so free it after one RCU grace period and one tasks + * trace RCU grace period. */ - bpf_map_put(ptr); + if (need_defer) + WRITE_ONCE(inner_map->free_after_mult_rcu_gp, true); + bpf_map_put(inner_map); } u32 bpf_map_fd_sys_lookup_elem(void *ptr) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 5e43ddd1b83f..dd515f6b9741 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -719,6 +719,28 @@ static void bpf_map_put_uref(struct bpf_map *map) } } +static void bpf_map_free_in_work(struct bpf_map *map) +{ + INIT_WORK(&map->work, bpf_map_free_deferred); + /* Avoid spawning kworkers, since they all might contend + * for the same mutex like slab_mutex. + */ + queue_work(system_unbound_wq, &map->work); +} + +static void bpf_map_free_rcu_gp(struct rcu_head *rcu) +{ + bpf_map_free_in_work(container_of(rcu, struct bpf_map, rcu)); +} + +static void bpf_map_free_mult_rcu_gp(struct rcu_head *rcu) +{ + if (rcu_trace_implies_rcu_gp()) + bpf_map_free_rcu_gp(rcu); + else + call_rcu(rcu, bpf_map_free_rcu_gp); +} + /* decrement map refcnt and schedule it for freeing via workqueue * (underlying map implementation ops->map_free() might sleep) */ @@ -728,11 +750,11 @@ void bpf_map_put(struct bpf_map *map) /* bpf_map_free_id() must be called first */ bpf_map_free_id(map); btf_put(map->btf); - INIT_WORK(&map->work, bpf_map_free_deferred); - /* Avoid spawning kworkers, since they all might contend - * for the same mutex like slab_mutex. - */ - queue_work(system_unbound_wq, &map->work); + + if (READ_ONCE(map->free_after_mult_rcu_gp)) + call_rcu_tasks_trace(&map->rcu, bpf_map_free_mult_rcu_gp); + else + bpf_map_free_in_work(map); } } EXPORT_SYMBOL_GPL(bpf_map_put); -- cgit v1.2.3 From af66bfd3c8538ed21cf72af18426fc4a408665cf Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Mon, 4 Dec 2023 22:04:23 +0800 Subject: bpf: Optimize the free of inner map When removing the inner map from the outer map, the inner map will be freed after one RCU grace period and one RCU tasks trace grace period, so it is certain that the bpf program, which may access the inner map, has exited before the inner map is freed. However there is no need to wait for one RCU tasks trace grace period if the outer map is only accessed by non-sleepable program. So adding sleepable_refcnt in bpf_map and increasing sleepable_refcnt when adding the outer map into env->used_maps for sleepable program. Although the max number of bpf program is INT_MAX - 1, the number of bpf programs which are being loaded may be greater than INT_MAX, so using atomic64_t instead of atomic_t for sleepable_refcnt. When removing the inner map from the outer map, using sleepable_refcnt to decide whether or not a RCU tasks trace grace period is needed before freeing the inner map. Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20231204140425.1480317-6-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 2 ++ kernel/bpf/core.c | 4 ++++ kernel/bpf/map_in_map.c | 14 +++++++++----- kernel/bpf/syscall.c | 8 ++++++++ kernel/bpf/verifier.c | 4 +++- 5 files changed, 26 insertions(+), 6 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index de3bd03cbeea..10e5e4d8a00f 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -297,6 +297,8 @@ struct bpf_map { bool bypass_spec_v1; bool frozen; /* write-once; write-protected by freeze_mutex */ bool free_after_mult_rcu_gp; + bool free_after_rcu_gp; + atomic64_t sleepable_refcnt; s64 __percpu *elem_count; }; diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index cd3afe57ece3..4b813da8d6c0 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -2664,12 +2664,16 @@ void __bpf_free_used_maps(struct bpf_prog_aux *aux, struct bpf_map **used_maps, u32 len) { struct bpf_map *map; + bool sleepable; u32 i; + sleepable = aux->sleepable; for (i = 0; i < len; i++) { map = used_maps[i]; if (map->ops->map_poke_untrack) map->ops->map_poke_untrack(map, aux); + if (sleepable) + atomic64_dec(&map->sleepable_refcnt); bpf_map_put(map); } } diff --git a/kernel/bpf/map_in_map.c b/kernel/bpf/map_in_map.c index 3248ff5d8161..8ef269e66ba5 100644 --- a/kernel/bpf/map_in_map.c +++ b/kernel/bpf/map_in_map.c @@ -131,12 +131,16 @@ void bpf_map_fd_put_ptr(struct bpf_map *map, void *ptr, bool need_defer) { struct bpf_map *inner_map = ptr; - /* The inner map may still be used by both non-sleepable and sleepable - * bpf program, so free it after one RCU grace period and one tasks - * trace RCU grace period. + /* Defer the freeing of inner map according to the sleepable attribute + * of bpf program which owns the outer map, so unnecessary waiting for + * RCU tasks trace grace period can be avoided. */ - if (need_defer) - WRITE_ONCE(inner_map->free_after_mult_rcu_gp, true); + if (need_defer) { + if (atomic64_read(&map->sleepable_refcnt)) + WRITE_ONCE(inner_map->free_after_mult_rcu_gp, true); + else + WRITE_ONCE(inner_map->free_after_rcu_gp, true); + } bpf_map_put(inner_map); } diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index dd515f6b9741..ebaccf77d56e 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -751,8 +751,11 @@ void bpf_map_put(struct bpf_map *map) bpf_map_free_id(map); btf_put(map->btf); + WARN_ON_ONCE(atomic64_read(&map->sleepable_refcnt)); if (READ_ONCE(map->free_after_mult_rcu_gp)) call_rcu_tasks_trace(&map->rcu, bpf_map_free_mult_rcu_gp); + else if (READ_ONCE(map->free_after_rcu_gp)) + call_rcu(&map->rcu, bpf_map_free_rcu_gp); else bpf_map_free_in_work(map); } @@ -5345,6 +5348,11 @@ static int bpf_prog_bind_map(union bpf_attr *attr) goto out_unlock; } + /* The bpf program will not access the bpf map, but for the sake of + * simplicity, increase sleepable_refcnt for sleepable program as well. + */ + if (prog->aux->sleepable) + atomic64_inc(&map->sleepable_refcnt); memcpy(used_maps_new, used_maps_old, sizeof(used_maps_old[0]) * prog->aux->used_map_cnt); used_maps_new[prog->aux->used_map_cnt] = map; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index cdb4f5f0ba79..1ed39665f802 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -17889,10 +17889,12 @@ static int resolve_pseudo_ldimm64(struct bpf_verifier_env *env) return -E2BIG; } + if (env->prog->aux->sleepable) + atomic64_inc(&map->sleepable_refcnt); /* hold the map. If the program is rejected by verifier, * the map will be released by release_maps() or it * will be used by the valid program until it's unloaded - * and all maps are released in free_used_maps() + * and all maps are released in bpf_free_used_maps() */ bpf_map_inc(map); -- cgit v1.2.3 From 41f6f64e6999a837048b1bd13a2f8742964eca6b Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 5 Dec 2023 10:42:39 -0800 Subject: bpf: support non-r10 register spill/fill to/from stack in precision tracking Use instruction (jump) history to record instructions that performed register spill/fill to/from stack, regardless if this was done through read-only r10 register, or any other register after copying r10 into it *and* potentially adjusting offset. To make this work reliably, we push extra per-instruction flags into instruction history, encoding stack slot index (spi) and stack frame number in extra 10 bit flags we take away from prev_idx in instruction history. We don't touch idx field for maximum performance, as it's checked most frequently during backtracking. This change removes basically the last remaining practical limitation of precision backtracking logic in BPF verifier. It fixes known deficiencies, but also opens up new opportunities to reduce number of verified states, explored in the subsequent patches. There are only three differences in selftests' BPF object files according to veristat, all in the positive direction (less states). File Program Insns (A) Insns (B) Insns (DIFF) States (A) States (B) States (DIFF) -------------------------------------- ------------- --------- --------- ------------- ---------- ---------- ------------- test_cls_redirect_dynptr.bpf.linked3.o cls_redirect 2987 2864 -123 (-4.12%) 240 231 -9 (-3.75%) xdp_synproxy_kern.bpf.linked3.o syncookie_tc 82848 82661 -187 (-0.23%) 5107 5073 -34 (-0.67%) xdp_synproxy_kern.bpf.linked3.o syncookie_xdp 85116 84964 -152 (-0.18%) 5162 5130 -32 (-0.62%) Note, I avoided renaming jmp_history to more generic insn_hist to minimize number of lines changed and potential merge conflicts between bpf and bpf-next trees. Notice also cur_hist_entry pointer reset to NULL at the beginning of instruction verification loop. This pointer avoids the problem of relying on last jump history entry's insn_idx to determine whether we already have entry for current instruction or not. It can happen that we added jump history entry because current instruction is_jmp_point(), but also we need to add instruction flags for stack access. In this case, we don't want to entries, so we need to reuse last added entry, if it is present. Relying on insn_idx comparison has the same ambiguity problem as the one that was fixed recently in [0], so we avoid that. [0] https://patchwork.kernel.org/project/netdevbpf/patch/20231110002638.4168352-3-andrii@kernel.org/ Acked-by: Eduard Zingerman Reported-by: Tao Lyu Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231205184248.1502704-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf_verifier.h | 31 +++- kernel/bpf/verifier.c | 175 ++++++++++++--------- .../bpf/progs/verifier_subprog_precision.c | 23 ++- tools/testing/selftests/bpf/verifier/precise.c | 38 +++-- 4 files changed, 169 insertions(+), 98 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 3378cc753061..bada59812e00 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -325,12 +325,34 @@ struct bpf_func_state { int allocated_stack; }; -struct bpf_idx_pair { - u32 prev_idx; +#define MAX_CALL_FRAMES 8 + +/* instruction history flags, used in bpf_jmp_history_entry.flags field */ +enum { + /* instruction references stack slot through PTR_TO_STACK register; + * we also store stack's frame number in lower 3 bits (MAX_CALL_FRAMES is 8) + * and accessed stack slot's index in next 6 bits (MAX_BPF_STACK is 512, + * 8 bytes per slot, so slot index (spi) is [0, 63]) + */ + INSN_F_FRAMENO_MASK = 0x7, /* 3 bits */ + + INSN_F_SPI_MASK = 0x3f, /* 6 bits */ + INSN_F_SPI_SHIFT = 3, /* shifted 3 bits to the left */ + + INSN_F_STACK_ACCESS = BIT(9), /* we need 10 bits total */ +}; + +static_assert(INSN_F_FRAMENO_MASK + 1 >= MAX_CALL_FRAMES); +static_assert(INSN_F_SPI_MASK + 1 >= MAX_BPF_STACK / 8); + +struct bpf_jmp_history_entry { u32 idx; + /* insn idx can't be bigger than 1 million */ + u32 prev_idx : 22; + /* special flags, e.g., whether insn is doing register stack spill/load */ + u32 flags : 10; }; -#define MAX_CALL_FRAMES 8 /* Maximum number of register states that can exist at once */ #define BPF_ID_MAP_SIZE ((MAX_BPF_REG + MAX_BPF_STACK / BPF_REG_SIZE) * MAX_CALL_FRAMES) struct bpf_verifier_state { @@ -413,7 +435,7 @@ struct bpf_verifier_state { * For most states jmp_history_cnt is [0-3]. * For loops can go up to ~40. */ - struct bpf_idx_pair *jmp_history; + struct bpf_jmp_history_entry *jmp_history; u32 jmp_history_cnt; u32 dfs_depth; u32 callback_unroll_depth; @@ -656,6 +678,7 @@ struct bpf_verifier_env { int cur_stack; } cfg; struct backtrack_state bt; + struct bpf_jmp_history_entry *cur_hist_ent; u32 pass_cnt; /* number of times do_check() was called */ u32 subprog_cnt; /* number of instructions analyzed by the verifier */ diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 1ed39665f802..9bc16dc66465 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1355,8 +1355,8 @@ static int copy_verifier_state(struct bpf_verifier_state *dst_state, int i, err; dst_state->jmp_history = copy_array(dst_state->jmp_history, src->jmp_history, - src->jmp_history_cnt, sizeof(struct bpf_idx_pair), - GFP_USER); + src->jmp_history_cnt, sizeof(*dst_state->jmp_history), + GFP_USER); if (!dst_state->jmp_history) return -ENOMEM; dst_state->jmp_history_cnt = src->jmp_history_cnt; @@ -3221,6 +3221,21 @@ static int check_reg_arg(struct bpf_verifier_env *env, u32 regno, return __check_reg_arg(env, state->regs, regno, t); } +static int insn_stack_access_flags(int frameno, int spi) +{ + return INSN_F_STACK_ACCESS | (spi << INSN_F_SPI_SHIFT) | frameno; +} + +static int insn_stack_access_spi(int insn_flags) +{ + return (insn_flags >> INSN_F_SPI_SHIFT) & INSN_F_SPI_MASK; +} + +static int insn_stack_access_frameno(int insn_flags) +{ + return insn_flags & INSN_F_FRAMENO_MASK; +} + static void mark_jmp_point(struct bpf_verifier_env *env, int idx) { env->insn_aux_data[idx].jmp_point = true; @@ -3232,28 +3247,51 @@ static bool is_jmp_point(struct bpf_verifier_env *env, int insn_idx) } /* for any branch, call, exit record the history of jmps in the given state */ -static int push_jmp_history(struct bpf_verifier_env *env, - struct bpf_verifier_state *cur) +static int push_jmp_history(struct bpf_verifier_env *env, struct bpf_verifier_state *cur, + int insn_flags) { u32 cnt = cur->jmp_history_cnt; - struct bpf_idx_pair *p; + struct bpf_jmp_history_entry *p; size_t alloc_size; - if (!is_jmp_point(env, env->insn_idx)) + /* combine instruction flags if we already recorded this instruction */ + if (env->cur_hist_ent) { + /* atomic instructions push insn_flags twice, for READ and + * WRITE sides, but they should agree on stack slot + */ + WARN_ONCE((env->cur_hist_ent->flags & insn_flags) && + (env->cur_hist_ent->flags & insn_flags) != insn_flags, + "verifier insn history bug: insn_idx %d cur flags %x new flags %x\n", + env->insn_idx, env->cur_hist_ent->flags, insn_flags); + env->cur_hist_ent->flags |= insn_flags; return 0; + } cnt++; alloc_size = kmalloc_size_roundup(size_mul(cnt, sizeof(*p))); p = krealloc(cur->jmp_history, alloc_size, GFP_USER); if (!p) return -ENOMEM; - p[cnt - 1].idx = env->insn_idx; - p[cnt - 1].prev_idx = env->prev_insn_idx; cur->jmp_history = p; + + p = &cur->jmp_history[cnt - 1]; + p->idx = env->insn_idx; + p->prev_idx = env->prev_insn_idx; + p->flags = insn_flags; cur->jmp_history_cnt = cnt; + env->cur_hist_ent = p; + return 0; } +static struct bpf_jmp_history_entry *get_jmp_hist_entry(struct bpf_verifier_state *st, + u32 hist_end, int insn_idx) +{ + if (hist_end > 0 && st->jmp_history[hist_end - 1].idx == insn_idx) + return &st->jmp_history[hist_end - 1]; + return NULL; +} + /* Backtrack one insn at a time. If idx is not at the top of recorded * history then previous instruction came from straight line execution. * Return -ENOENT if we exhausted all instructions within given state. @@ -3415,9 +3453,14 @@ static inline bool bt_is_reg_set(struct backtrack_state *bt, u32 reg) return bt->reg_masks[bt->frame] & (1 << reg); } +static inline bool bt_is_frame_slot_set(struct backtrack_state *bt, u32 frame, u32 slot) +{ + return bt->stack_masks[frame] & (1ull << slot); +} + static inline bool bt_is_slot_set(struct backtrack_state *bt, u32 slot) { - return bt->stack_masks[bt->frame] & (1ull << slot); + return bt_is_frame_slot_set(bt, bt->frame, slot); } /* format registers bitmask, e.g., "r0,r2,r4" for 0x15 mask */ @@ -3471,7 +3514,7 @@ static bool calls_callback(struct bpf_verifier_env *env, int insn_idx); * - *was* processed previously during backtracking. */ static int backtrack_insn(struct bpf_verifier_env *env, int idx, int subseq_idx, - struct backtrack_state *bt) + struct bpf_jmp_history_entry *hist, struct backtrack_state *bt) { const struct bpf_insn_cbs cbs = { .cb_call = disasm_kfunc_name, @@ -3484,7 +3527,7 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx, int subseq_idx, u8 mode = BPF_MODE(insn->code); u32 dreg = insn->dst_reg; u32 sreg = insn->src_reg; - u32 spi, i; + u32 spi, i, fr; if (insn->code == 0) return 0; @@ -3545,20 +3588,15 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx, int subseq_idx, * by 'precise' mark in corresponding register of this state. * No further tracking necessary. */ - if (insn->src_reg != BPF_REG_FP) + if (!hist || !(hist->flags & INSN_F_STACK_ACCESS)) return 0; - /* dreg = *(u64 *)[fp - off] was a fill from the stack. * that [fp - off] slot contains scalar that needs to be * tracked with precision */ - spi = (-insn->off - 1) / BPF_REG_SIZE; - if (spi >= 64) { - verbose(env, "BUG spi %d\n", spi); - WARN_ONCE(1, "verifier backtracking bug"); - return -EFAULT; - } - bt_set_slot(bt, spi); + spi = insn_stack_access_spi(hist->flags); + fr = insn_stack_access_frameno(hist->flags); + bt_set_frame_slot(bt, fr, spi); } else if (class == BPF_STX || class == BPF_ST) { if (bt_is_reg_set(bt, dreg)) /* stx & st shouldn't be using _scalar_ dst_reg @@ -3567,17 +3605,13 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx, int subseq_idx, */ return -ENOTSUPP; /* scalars can only be spilled into stack */ - if (insn->dst_reg != BPF_REG_FP) + if (!hist || !(hist->flags & INSN_F_STACK_ACCESS)) return 0; - spi = (-insn->off - 1) / BPF_REG_SIZE; - if (spi >= 64) { - verbose(env, "BUG spi %d\n", spi); - WARN_ONCE(1, "verifier backtracking bug"); - return -EFAULT; - } - if (!bt_is_slot_set(bt, spi)) + spi = insn_stack_access_spi(hist->flags); + fr = insn_stack_access_frameno(hist->flags); + if (!bt_is_frame_slot_set(bt, fr, spi)) return 0; - bt_clear_slot(bt, spi); + bt_clear_frame_slot(bt, fr, spi); if (class == BPF_STX) bt_set_reg(bt, sreg); } else if (class == BPF_JMP || class == BPF_JMP32) { @@ -3621,10 +3655,14 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx, int subseq_idx, WARN_ONCE(1, "verifier backtracking bug"); return -EFAULT; } - /* we don't track register spills perfectly, - * so fallback to force-precise instead of failing */ - if (bt_stack_mask(bt) != 0) - return -ENOTSUPP; + /* we are now tracking register spills correctly, + * so any instance of leftover slots is a bug + */ + if (bt_stack_mask(bt) != 0) { + verbose(env, "BUG stack slots %llx\n", bt_stack_mask(bt)); + WARN_ONCE(1, "verifier backtracking bug (subprog leftover stack slots)"); + return -EFAULT; + } /* propagate r1-r5 to the caller */ for (i = BPF_REG_1; i <= BPF_REG_5; i++) { if (bt_is_reg_set(bt, i)) { @@ -3649,8 +3687,11 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx, int subseq_idx, WARN_ONCE(1, "verifier backtracking bug"); return -EFAULT; } - if (bt_stack_mask(bt) != 0) - return -ENOTSUPP; + if (bt_stack_mask(bt) != 0) { + verbose(env, "BUG stack slots %llx\n", bt_stack_mask(bt)); + WARN_ONCE(1, "verifier backtracking bug (callback leftover stack slots)"); + return -EFAULT; + } /* clear r1-r5 in callback subprog's mask */ for (i = BPF_REG_1; i <= BPF_REG_5; i++) bt_clear_reg(bt, i); @@ -4087,6 +4128,7 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno) for (;;) { DECLARE_BITMAP(mask, 64); u32 history = st->jmp_history_cnt; + struct bpf_jmp_history_entry *hist; if (env->log.level & BPF_LOG_LEVEL2) { verbose(env, "mark_precise: frame%d: last_idx %d first_idx %d subseq_idx %d \n", @@ -4150,7 +4192,8 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno) err = 0; skip_first = false; } else { - err = backtrack_insn(env, i, subseq_idx, bt); + hist = get_jmp_hist_entry(st, history, i); + err = backtrack_insn(env, i, subseq_idx, hist, bt); } if (err == -ENOTSUPP) { mark_all_scalars_precise(env, env->cur_state); @@ -4203,22 +4246,10 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno) bitmap_from_u64(mask, bt_frame_stack_mask(bt, fr)); for_each_set_bit(i, mask, 64) { if (i >= func->allocated_stack / BPF_REG_SIZE) { - /* the sequence of instructions: - * 2: (bf) r3 = r10 - * 3: (7b) *(u64 *)(r3 -8) = r0 - * 4: (79) r4 = *(u64 *)(r10 -8) - * doesn't contain jmps. It's backtracked - * as a single block. - * During backtracking insn 3 is not recognized as - * stack access, so at the end of backtracking - * stack slot fp-8 is still marked in stack_mask. - * However the parent state may not have accessed - * fp-8 and it's "unallocated" stack space. - * In such case fallback to conservative. - */ - mark_all_scalars_precise(env, env->cur_state); - bt_reset(bt); - return 0; + verbose(env, "BUG backtracking (stack slot %d, total slots %d)\n", + i, func->allocated_stack / BPF_REG_SIZE); + WARN_ONCE(1, "verifier backtracking bug (stack slot out of bounds)"); + return -EFAULT; } if (!is_spilled_scalar_reg(&func->stack[i])) { @@ -4391,7 +4422,7 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err; struct bpf_insn *insn = &env->prog->insnsi[insn_idx]; struct bpf_reg_state *reg = NULL; - u32 dst_reg = insn->dst_reg; + int insn_flags = insn_stack_access_flags(state->frameno, spi); err = grow_stack_state(state, round_up(slot + 1, BPF_REG_SIZE)); if (err) @@ -4432,17 +4463,6 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, mark_stack_slot_scratched(env, spi); if (reg && !(off % BPF_REG_SIZE) && register_is_bounded(reg) && !register_is_null(reg) && env->bpf_capable) { - if (dst_reg != BPF_REG_FP) { - /* The backtracking logic can only recognize explicit - * stack slot address like [fp - 8]. Other spill of - * scalar via different register has to be conservative. - * Backtrack from here and mark all registers as precise - * that contributed into 'reg' being a constant. - */ - err = mark_chain_precision(env, value_regno); - if (err) - return err; - } save_register_state(state, spi, reg, size); /* Break the relation on a narrowing spill. */ if (fls64(reg->umax_value) > BITS_PER_BYTE * size) @@ -4454,6 +4474,7 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, __mark_reg_known(&fake_reg, insn->imm); fake_reg.type = SCALAR_VALUE; save_register_state(state, spi, &fake_reg, size); + insn_flags = 0; /* not a register spill */ } else if (reg && is_spillable_regtype(reg->type)) { /* register containing pointer is being spilled into stack */ if (size != BPF_REG_SIZE) { @@ -4499,9 +4520,12 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, /* Mark slots affected by this stack write. */ for (i = 0; i < size; i++) - state->stack[spi].slot_type[(slot - i) % BPF_REG_SIZE] = - type; + state->stack[spi].slot_type[(slot - i) % BPF_REG_SIZE] = type; + insn_flags = 0; /* not a register spill */ } + + if (insn_flags) + return push_jmp_history(env, env->cur_state, insn_flags); return 0; } @@ -4694,6 +4718,7 @@ static int check_stack_read_fixed_off(struct bpf_verifier_env *env, int i, slot = -off - 1, spi = slot / BPF_REG_SIZE; struct bpf_reg_state *reg; u8 *stype, type; + int insn_flags = insn_stack_access_flags(reg_state->frameno, spi); stype = reg_state->stack[spi].slot_type; reg = ®_state->stack[spi].spilled_ptr; @@ -4739,12 +4764,10 @@ static int check_stack_read_fixed_off(struct bpf_verifier_env *env, return -EACCES; } mark_reg_unknown(env, state->regs, dst_regno); + insn_flags = 0; /* not restoring original register state */ } state->regs[dst_regno].live |= REG_LIVE_WRITTEN; - return 0; - } - - if (dst_regno >= 0) { + } else if (dst_regno >= 0) { /* restore register state from stack */ copy_register_state(&state->regs[dst_regno], reg); /* mark reg as written since spilled pointer state likely @@ -4780,7 +4803,10 @@ static int check_stack_read_fixed_off(struct bpf_verifier_env *env, mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64); if (dst_regno >= 0) mark_reg_stack_read(env, reg_state, off, off + size, dst_regno); + insn_flags = 0; /* we are not restoring spilled register */ } + if (insn_flags) + return push_jmp_history(env, env->cur_state, insn_flags); return 0; } @@ -6940,7 +6966,6 @@ static int check_atomic(struct bpf_verifier_env *env, int insn_idx, struct bpf_i BPF_SIZE(insn->code), BPF_WRITE, -1, true, false); if (err) return err; - return 0; } @@ -16910,7 +16935,8 @@ hit: * the precision needs to be propagated back in * the current state. */ - err = err ? : push_jmp_history(env, cur); + if (is_jmp_point(env, env->insn_idx)) + err = err ? : push_jmp_history(env, cur, 0); err = err ? : propagate_precision(env, &sl->state); if (err) return err; @@ -17135,6 +17161,9 @@ static int do_check(struct bpf_verifier_env *env) u8 class; int err; + /* reset current history entry on each new instruction */ + env->cur_hist_ent = NULL; + env->prev_insn_idx = prev_insn_idx; if (env->insn_idx >= insn_cnt) { verbose(env, "invalid insn idx %d insn_cnt %d\n", @@ -17174,7 +17203,7 @@ static int do_check(struct bpf_verifier_env *env) } if (is_jmp_point(env, env->insn_idx)) { - err = push_jmp_history(env, state); + err = push_jmp_history(env, state, 0); if (err) return err; } diff --git a/tools/testing/selftests/bpf/progs/verifier_subprog_precision.c b/tools/testing/selftests/bpf/progs/verifier_subprog_precision.c index 0dfe3f8b69ac..eba98fab2f54 100644 --- a/tools/testing/selftests/bpf/progs/verifier_subprog_precision.c +++ b/tools/testing/selftests/bpf/progs/verifier_subprog_precision.c @@ -589,11 +589,24 @@ static __u64 subprog_spill_reg_precise(void) SEC("?raw_tp") __success __log_level(2) -/* precision backtracking can't currently handle stack access not through r10, - * so we won't be able to mark stack slot fp-8 as precise, and so will - * fallback to forcing all as precise - */ -__msg("mark_precise: frame0: falling back to forcing all scalars precise") +__msg("10: (0f) r1 += r7") +__msg("mark_precise: frame0: last_idx 10 first_idx 7 subseq_idx -1") +__msg("mark_precise: frame0: regs=r7 stack= before 9: (bf) r1 = r8") +__msg("mark_precise: frame0: regs=r7 stack= before 8: (27) r7 *= 4") +__msg("mark_precise: frame0: regs=r7 stack= before 7: (79) r7 = *(u64 *)(r10 -8)") +__msg("mark_precise: frame0: parent state regs= stack=-8: R0_w=2 R6_w=1 R8_rw=map_value(map=.data.vals,ks=4,vs=16) R10=fp0 fp-8_rw=P1") +__msg("mark_precise: frame0: last_idx 18 first_idx 0 subseq_idx 7") +__msg("mark_precise: frame0: regs= stack=-8 before 18: (95) exit") +__msg("mark_precise: frame1: regs= stack= before 17: (0f) r0 += r2") +__msg("mark_precise: frame1: regs= stack= before 16: (79) r2 = *(u64 *)(r1 +0)") +__msg("mark_precise: frame1: regs= stack= before 15: (79) r0 = *(u64 *)(r10 -16)") +__msg("mark_precise: frame1: regs= stack= before 14: (7b) *(u64 *)(r10 -16) = r2") +__msg("mark_precise: frame1: regs= stack= before 13: (7b) *(u64 *)(r1 +0) = r2") +__msg("mark_precise: frame1: regs=r2 stack= before 6: (85) call pc+6") +__msg("mark_precise: frame0: regs=r2 stack= before 5: (bf) r2 = r6") +__msg("mark_precise: frame0: regs=r6 stack= before 4: (07) r1 += -8") +__msg("mark_precise: frame0: regs=r6 stack= before 3: (bf) r1 = r10") +__msg("mark_precise: frame0: regs=r6 stack= before 2: (b7) r6 = 1") __naked int subprog_spill_into_parent_stack_slot_precise(void) { asm volatile ( diff --git a/tools/testing/selftests/bpf/verifier/precise.c b/tools/testing/selftests/bpf/verifier/precise.c index 0d84dd1f38b6..8a2ff81d8350 100644 --- a/tools/testing/selftests/bpf/verifier/precise.c +++ b/tools/testing/selftests/bpf/verifier/precise.c @@ -140,10 +140,11 @@ .result = REJECT, }, { - "precise: ST insn causing spi > allocated_stack", + "precise: ST zero to stack insn is supported", .insns = { BPF_MOV64_REG(BPF_REG_3, BPF_REG_10), BPF_JMP_IMM(BPF_JNE, BPF_REG_3, 123, 0), + /* not a register spill, so we stop precision propagation for R4 here */ BPF_ST_MEM(BPF_DW, BPF_REG_3, -8, 0), BPF_LDX_MEM(BPF_DW, BPF_REG_4, BPF_REG_10, -8), BPF_MOV64_IMM(BPF_REG_0, -1), @@ -157,11 +158,11 @@ mark_precise: frame0: last_idx 4 first_idx 2\ mark_precise: frame0: regs=r4 stack= before 4\ mark_precise: frame0: regs=r4 stack= before 3\ - mark_precise: frame0: regs= stack=-8 before 2\ - mark_precise: frame0: falling back to forcing all scalars precise\ - force_precise: frame0: forcing r0 to be precise\ mark_precise: frame0: last_idx 5 first_idx 5\ - mark_precise: frame0: parent state regs= stack=:", + mark_precise: frame0: parent state regs=r0 stack=:\ + mark_precise: frame0: last_idx 4 first_idx 2\ + mark_precise: frame0: regs=r0 stack= before 4\ + 5: R0=-1 R4=0", .result = VERBOSE_ACCEPT, .retval = -1, }, @@ -169,6 +170,8 @@ "precise: STX insn causing spi > allocated_stack", .insns = { BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_get_prandom_u32), + /* make later reg spill more interesting by having somewhat known scalar */ + BPF_ALU64_IMM(BPF_AND, BPF_REG_0, 0xff), BPF_MOV64_REG(BPF_REG_3, BPF_REG_10), BPF_JMP_IMM(BPF_JNE, BPF_REG_3, 123, 0), BPF_STX_MEM(BPF_DW, BPF_REG_3, BPF_REG_0, -8), @@ -179,18 +182,21 @@ }, .prog_type = BPF_PROG_TYPE_XDP, .flags = BPF_F_TEST_STATE_FREQ, - .errstr = "mark_precise: frame0: last_idx 6 first_idx 6\ + .errstr = "mark_precise: frame0: last_idx 7 first_idx 7\ mark_precise: frame0: parent state regs=r4 stack=:\ - mark_precise: frame0: last_idx 5 first_idx 3\ - mark_precise: frame0: regs=r4 stack= before 5\ - mark_precise: frame0: regs=r4 stack= before 4\ - mark_precise: frame0: regs= stack=-8 before 3\ - mark_precise: frame0: falling back to forcing all scalars precise\ - force_precise: frame0: forcing r0 to be precise\ - force_precise: frame0: forcing r0 to be precise\ - force_precise: frame0: forcing r0 to be precise\ - force_precise: frame0: forcing r0 to be precise\ - mark_precise: frame0: last_idx 6 first_idx 6\ + mark_precise: frame0: last_idx 6 first_idx 4\ + mark_precise: frame0: regs=r4 stack= before 6: (b7) r0 = -1\ + mark_precise: frame0: regs=r4 stack= before 5: (79) r4 = *(u64 *)(r10 -8)\ + mark_precise: frame0: regs= stack=-8 before 4: (7b) *(u64 *)(r3 -8) = r0\ + mark_precise: frame0: parent state regs=r0 stack=:\ + mark_precise: frame0: last_idx 3 first_idx 3\ + mark_precise: frame0: regs=r0 stack= before 3: (55) if r3 != 0x7b goto pc+0\ + mark_precise: frame0: regs=r0 stack= before 2: (bf) r3 = r10\ + mark_precise: frame0: regs=r0 stack= before 1: (57) r0 &= 255\ + mark_precise: frame0: parent state regs=r0 stack=:\ + mark_precise: frame0: last_idx 0 first_idx 0\ + mark_precise: frame0: regs=r0 stack= before 0: (85) call bpf_get_prandom_u32#7\ + mark_precise: frame0: last_idx 7 first_idx 7\ mark_precise: frame0: parent state regs= stack=:", .result = VERBOSE_ACCEPT, .retval = -1, -- cgit v1.2.3 From ab125ed3ec1c10ccc36bc98c7a4256ad114a3dae Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 5 Dec 2023 10:42:41 -0800 Subject: bpf: fix check for attempt to corrupt spilled pointer When register is spilled onto a stack as a 1/2/4-byte register, we set slot_type[BPF_REG_SIZE - 1] (plus potentially few more below it, depending on actual spill size). So to check if some stack slot has spilled register we need to consult slot_type[7], not slot_type[0]. To avoid the need to remember and double-check this in the future, just use is_spilled_reg() helper. Fixes: 27113c59b6d0 ("bpf: Check the other end of slot_type for STACK_SPILL") Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231205184248.1502704-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9bc16dc66465..3edca06de9fd 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4431,7 +4431,7 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, * so it's aligned access and [off, off + size) are within stack limits */ if (!env->allow_ptr_leaks && - state->stack[spi].slot_type[0] == STACK_SPILL && + is_spilled_reg(&state->stack[spi]) && size != BPF_REG_SIZE) { verbose(env, "attempt to corrupt spilled pointer on stack\n"); return -EACCES; -- cgit v1.2.3 From eaf18febd6ebc381aeb61543705148b3e28c7c47 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 5 Dec 2023 10:42:42 -0800 Subject: bpf: preserve STACK_ZERO slots on partial reg spills Instead of always forcing STACK_ZERO slots to STACK_MISC, preserve it in situations where this is possible. E.g., when spilling register as 1/2/4-byte subslots on the stack, all the remaining bytes in the stack slot do not automatically become unknown. If we knew they contained zeroes, we can preserve those STACK_ZERO markers. Add a helper mark_stack_slot_misc(), similar to scrub_spilled_slot(), but that doesn't overwrite either STACK_INVALID nor STACK_ZERO. Note that we need to take into account possibility of being in unprivileged mode, in which case STACK_INVALID is forced to STACK_MISC for correctness, as treating STACK_INVALID as equivalent STACK_MISC is only enabled in privileged mode. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231205184248.1502704-5-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 28 +++++++++++++++++++++++----- 1 file changed, 23 insertions(+), 5 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 3edca06de9fd..93de39a6e36e 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1144,6 +1144,21 @@ static bool is_spilled_scalar_reg(const struct bpf_stack_state *stack) stack->spilled_ptr.type == SCALAR_VALUE; } +/* Mark stack slot as STACK_MISC, unless it is already STACK_INVALID, in which + * case they are equivalent, or it's STACK_ZERO, in which case we preserve + * more precise STACK_ZERO. + * Note, in uprivileged mode leaving STACK_INVALID is wrong, so we take + * env->allow_ptr_leaks into account and force STACK_MISC, if necessary. + */ +static void mark_stack_slot_misc(struct bpf_verifier_env *env, u8 *stype) +{ + if (*stype == STACK_ZERO) + return; + if (env->allow_ptr_leaks && *stype == STACK_INVALID) + return; + *stype = STACK_MISC; +} + static void scrub_spilled_slot(u8 *stype) { if (*stype != STACK_INVALID) @@ -4386,7 +4401,8 @@ static void copy_register_state(struct bpf_reg_state *dst, const struct bpf_reg_ dst->live = live; } -static void save_register_state(struct bpf_func_state *state, +static void save_register_state(struct bpf_verifier_env *env, + struct bpf_func_state *state, int spi, struct bpf_reg_state *reg, int size) { @@ -4401,7 +4417,7 @@ static void save_register_state(struct bpf_func_state *state, /* size < 8 bytes spill */ for (; i; i--) - scrub_spilled_slot(&state->stack[spi].slot_type[i - 1]); + mark_stack_slot_misc(env, &state->stack[spi].slot_type[i - 1]); } static bool is_bpf_st_mem(struct bpf_insn *insn) @@ -4463,7 +4479,7 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, mark_stack_slot_scratched(env, spi); if (reg && !(off % BPF_REG_SIZE) && register_is_bounded(reg) && !register_is_null(reg) && env->bpf_capable) { - save_register_state(state, spi, reg, size); + save_register_state(env, state, spi, reg, size); /* Break the relation on a narrowing spill. */ if (fls64(reg->umax_value) > BITS_PER_BYTE * size) state->stack[spi].spilled_ptr.id = 0; @@ -4473,7 +4489,7 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, __mark_reg_known(&fake_reg, insn->imm); fake_reg.type = SCALAR_VALUE; - save_register_state(state, spi, &fake_reg, size); + save_register_state(env, state, spi, &fake_reg, size); insn_flags = 0; /* not a register spill */ } else if (reg && is_spillable_regtype(reg->type)) { /* register containing pointer is being spilled into stack */ @@ -4486,7 +4502,7 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, verbose(env, "cannot spill pointers to stack into stack frame of the caller\n"); return -EINVAL; } - save_register_state(state, spi, reg, size); + save_register_state(env, state, spi, reg, size); } else { u8 type = STACK_MISC; @@ -4757,6 +4773,8 @@ static int check_stack_read_fixed_off(struct bpf_verifier_env *env, continue; if (type == STACK_MISC) continue; + if (type == STACK_ZERO) + continue; if (type == STACK_INVALID && env->allow_uninit_stack) continue; verbose(env, "invalid read from stack off %d+%d size %d\n", -- cgit v1.2.3 From e322f0bcb8d371f4606eaf141c7f967e1a79bcb7 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 5 Dec 2023 10:42:44 -0800 Subject: bpf: preserve constant zero when doing partial register restore Similar to special handling of STACK_ZERO, when reading 1/2/4 bytes from stack from slot that has register spilled into it and that register has a constant value zero, preserve that zero and mark spilled register as precise for that. This makes spilled const zero register and STACK_ZERO cases equivalent in their behavior. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231205184248.1502704-7-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 93de39a6e36e..1ebe76c98451 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4767,22 +4767,39 @@ static int check_stack_read_fixed_off(struct bpf_verifier_env *env, copy_register_state(&state->regs[dst_regno], reg); state->regs[dst_regno].subreg_def = subreg_def; } else { + int spill_cnt = 0, zero_cnt = 0; + for (i = 0; i < size; i++) { type = stype[(slot - i) % BPF_REG_SIZE]; - if (type == STACK_SPILL) + if (type == STACK_SPILL) { + spill_cnt++; continue; + } if (type == STACK_MISC) continue; - if (type == STACK_ZERO) + if (type == STACK_ZERO) { + zero_cnt++; continue; + } if (type == STACK_INVALID && env->allow_uninit_stack) continue; verbose(env, "invalid read from stack off %d+%d size %d\n", off, i, size); return -EACCES; } - mark_reg_unknown(env, state->regs, dst_regno); - insn_flags = 0; /* not restoring original register state */ + + if (spill_cnt == size && + tnum_is_const(reg->var_off) && reg->var_off.value == 0) { + __mark_reg_const_zero(&state->regs[dst_regno]); + /* this IS register fill, so keep insn_flags */ + } else if (zero_cnt == size) { + /* similarly to mark_reg_stack_read(), preserve zeroes */ + __mark_reg_const_zero(&state->regs[dst_regno]); + insn_flags = 0; /* not restoring original register state */ + } else { + mark_reg_unknown(env, state->regs, dst_regno); + insn_flags = 0; /* not restoring original register state */ + } } state->regs[dst_regno].live |= REG_LIVE_WRITTEN; } else if (dst_regno >= 0) { -- cgit v1.2.3 From 18a433b62061e3d787bfc3e670fa711fecbd7cb4 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 5 Dec 2023 10:42:46 -0800 Subject: bpf: track aligned STACK_ZERO cases as imprecise spilled registers Now that precision backtracing is supporting register spill/fill to/from stack, there is another oportunity to be exploited here: minimizing precise STACK_ZERO cases. With a simple code change we can rely on initially imprecise register spill tracking for cases when register spilled to stack was a known zero. This is a very common case for initializing on the stack variables, including rather large structures. Often times zero has no special meaning for the subsequent BPF program logic and is often overwritten with non-zero values soon afterwards. But due to STACK_ZERO vs STACK_MISC tracking, such initial zero initialization actually causes duplication of verifier states as STACK_ZERO is clearly different than STACK_MISC or spilled SCALAR_VALUE register. The effect of this (now) trivial change is huge, as can be seen below. These are differences between BPF selftests, Cilium, and Meta-internal BPF object files relative to previous patch in this series. You can see improvements ranging from single-digit percentage improvement for instructions and states, all the way to 50-60% reduction for some of Meta-internal host agent programs, and even some Cilium programs. For Meta-internal ones I left only the differences for largest BPF object files by states/instructions, as there were too many differences in the overall output. All the differences were improvements, reducting number of states and thus instructions validated. Note, Meta-internal BPF object file names are not printed below. Many copies of balancer_ingress are actually many different configurations of Katran, so they are different BPF programs, which explains state reduction going from -16% all the way to 31%, depending on BPF program logic complexity. I also tooked a closer look at a few small-ish BPF programs to validate the behavior. Let's take bpf_iter_netrlink.bpf.o (first row below). While it's just 8 vs 5 states, verifier log is still pretty long to include it here. But the reduction in states is due to the following piece of C code: unsigned long ino; ... sk = s->sk_socket; if (!sk) { ino = 0; } else { inode = SOCK_INODE(sk); bpf_probe_read_kernel(&ino, sizeof(ino), &inode->i_ino); } BPF_SEQ_PRINTF(seq, "%-8u %-8lu\n", s->sk_drops.counter, ino); return 0; You can see that in some situations `ino` is zero-initialized, while in others it's unknown value filled out by bpf_probe_read_kernel(). Before this change code after if/else branches have to be validated twice. Once with (precise) ino == 0, due to eager STACK_ZERO logic, and then again for when ino is just STACK_MISC. But BPF_SEQ_PRINTF() doesn't care about precise value of ino, so with the change in this patch verifier is able to prune states from after one of the branches, reducing number of total states (and instructions) required for successful validation. Similar principle applies to bigger real-world applications, just at a much larger scale. SELFTESTS ========= File Program Insns (A) Insns (B) Insns (DIFF) States (A) States (B) States (DIFF) --------------------------------------- ----------------------- --------- --------- --------------- ---------- ---------- ------------- bpf_iter_netlink.bpf.linked3.o dump_netlink 148 104 -44 (-29.73%) 8 5 -3 (-37.50%) bpf_iter_unix.bpf.linked3.o dump_unix 8474 8404 -70 (-0.83%) 151 147 -4 (-2.65%) bpf_loop.bpf.linked3.o stack_check 560 324 -236 (-42.14%) 42 24 -18 (-42.86%) local_storage_bench.bpf.linked3.o get_local 120 77 -43 (-35.83%) 9 6 -3 (-33.33%) loop6.bpf.linked3.o trace_virtqueue_add_sgs 10167 9868 -299 (-2.94%) 226 206 -20 (-8.85%) pyperf600_bpf_loop.bpf.linked3.o on_event 4872 3423 -1449 (-29.74%) 322 229 -93 (-28.88%) strobemeta.bpf.linked3.o on_event 180697 176036 -4661 (-2.58%) 4780 4734 -46 (-0.96%) test_cls_redirect.bpf.linked3.o cls_redirect 65594 65401 -193 (-0.29%) 4230 4212 -18 (-0.43%) test_global_func_args.bpf.linked3.o test_cls 145 136 -9 (-6.21%) 10 9 -1 (-10.00%) test_l4lb.bpf.linked3.o balancer_ingress 4760 2612 -2148 (-45.13%) 113 102 -11 (-9.73%) test_l4lb_noinline.bpf.linked3.o balancer_ingress 4845 4877 +32 (+0.66%) 219 221 +2 (+0.91%) test_l4lb_noinline_dynptr.bpf.linked3.o balancer_ingress 2072 2087 +15 (+0.72%) 97 98 +1 (+1.03%) test_seg6_loop.bpf.linked3.o __add_egr_x 12440 9975 -2465 (-19.82%) 364 353 -11 (-3.02%) test_tcp_hdr_options.bpf.linked3.o estab 2558 2572 +14 (+0.55%) 179 180 +1 (+0.56%) test_xdp_dynptr.bpf.linked3.o _xdp_tx_iptunnel 645 596 -49 (-7.60%) 26 24 -2 (-7.69%) test_xdp_noinline.bpf.linked3.o balancer_ingress_v6 3520 3516 -4 (-0.11%) 216 216 +0 (+0.00%) xdp_synproxy_kern.bpf.linked3.o syncookie_tc 82661 81241 -1420 (-1.72%) 5073 5155 +82 (+1.62%) xdp_synproxy_kern.bpf.linked3.o syncookie_xdp 84964 82297 -2667 (-3.14%) 5130 5157 +27 (+0.53%) META-INTERNAL ============= Program Insns (A) Insns (B) Insns (DIFF) States (A) States (B) States (DIFF) -------------------------------------- --------- --------- ----------------- ---------- ---------- --------------- balancer_ingress 27925 23608 -4317 (-15.46%) 1488 1482 -6 (-0.40%) balancer_ingress 31824 27546 -4278 (-13.44%) 1658 1652 -6 (-0.36%) balancer_ingress 32213 27935 -4278 (-13.28%) 1689 1683 -6 (-0.36%) balancer_ingress 32213 27935 -4278 (-13.28%) 1689 1683 -6 (-0.36%) balancer_ingress 31824 27546 -4278 (-13.44%) 1658 1652 -6 (-0.36%) balancer_ingress 38647 29562 -9085 (-23.51%) 2069 1835 -234 (-11.31%) balancer_ingress 38647 29562 -9085 (-23.51%) 2069 1835 -234 (-11.31%) balancer_ingress 40339 30792 -9547 (-23.67%) 2193 1934 -259 (-11.81%) balancer_ingress 37321 29055 -8266 (-22.15%) 1972 1795 -177 (-8.98%) balancer_ingress 38176 29753 -8423 (-22.06%) 2008 1831 -177 (-8.81%) balancer_ingress 29193 20910 -8283 (-28.37%) 1599 1422 -177 (-11.07%) balancer_ingress 30013 21452 -8561 (-28.52%) 1645 1447 -198 (-12.04%) balancer_ingress 28691 24290 -4401 (-15.34%) 1545 1531 -14 (-0.91%) balancer_ingress 34223 28965 -5258 (-15.36%) 1984 1875 -109 (-5.49%) balancer_ingress 35481 26158 -9323 (-26.28%) 2095 1806 -289 (-13.79%) balancer_ingress 35481 26158 -9323 (-26.28%) 2095 1806 -289 (-13.79%) balancer_ingress 35868 26455 -9413 (-26.24%) 2140 1827 -313 (-14.63%) balancer_ingress 35868 26455 -9413 (-26.24%) 2140 1827 -313 (-14.63%) balancer_ingress 35481 26158 -9323 (-26.28%) 2095 1806 -289 (-13.79%) balancer_ingress 35481 26158 -9323 (-26.28%) 2095 1806 -289 (-13.79%) balancer_ingress 34844 29485 -5359 (-15.38%) 2036 1918 -118 (-5.80%) fbflow_egress 3256 2652 -604 (-18.55%) 218 192 -26 (-11.93%) fbflow_ingress 1026 944 -82 (-7.99%) 70 63 -7 (-10.00%) sslwall_tc_egress 8424 7360 -1064 (-12.63%) 498 458 -40 (-8.03%) syar_accept_protect 15040 9539 -5501 (-36.58%) 364 220 -144 (-39.56%) syar_connect_tcp_v6 15036 9535 -5501 (-36.59%) 360 216 -144 (-40.00%) syar_connect_udp_v4 15039 9538 -5501 (-36.58%) 361 217 -144 (-39.89%) syar_connect_connect4_protect4 24805 15833 -8972 (-36.17%) 756 480 -276 (-36.51%) syar_lsm_file_open 167772 151813 -15959 (-9.51%) 1836 1667 -169 (-9.20%) syar_namespace_create_new 14805 9304 -5501 (-37.16%) 353 209 -144 (-40.79%) syar_python3_detect 17531 12030 -5501 (-31.38%) 391 247 -144 (-36.83%) syar_ssh_post_fork 16412 10911 -5501 (-33.52%) 405 261 -144 (-35.56%) syar_enter_execve 14728 9227 -5501 (-37.35%) 345 201 -144 (-41.74%) syar_enter_execveat 14728 9227 -5501 (-37.35%) 345 201 -144 (-41.74%) syar_exit_execve 16622 11121 -5501 (-33.09%) 376 232 -144 (-38.30%) syar_exit_execveat 16622 11121 -5501 (-33.09%) 376 232 -144 (-38.30%) syar_syscalls_kill 15288 9787 -5501 (-35.98%) 398 254 -144 (-36.18%) syar_task_enter_pivot_root 14898 9397 -5501 (-36.92%) 357 213 -144 (-40.34%) syar_syscalls_setreuid 16678 11177 -5501 (-32.98%) 429 285 -144 (-33.57%) syar_syscalls_setuid 16678 11177 -5501 (-32.98%) 429 285 -144 (-33.57%) syar_syscalls_process_vm_readv 14959 9458 -5501 (-36.77%) 364 220 -144 (-39.56%) syar_syscalls_process_vm_writev 15757 10256 -5501 (-34.91%) 390 246 -144 (-36.92%) do_uprobe 15519 10018 -5501 (-35.45%) 373 229 -144 (-38.61%) edgewall 179715 55783 -123932 (-68.96%) 12607 3999 -8608 (-68.28%) bictcp_state 7570 4131 -3439 (-45.43%) 496 269 -227 (-45.77%) cubictcp_state 7570 4131 -3439 (-45.43%) 496 269 -227 (-45.77%) tcp_rate_skb_delivered 447 272 -175 (-39.15%) 29 18 -11 (-37.93%) kprobe__bbr_set_state 4566 2615 -1951 (-42.73%) 209 124 -85 (-40.67%) kprobe__bictcp_state 4566 2615 -1951 (-42.73%) 209 124 -85 (-40.67%) inet_sock_set_state 1501 1337 -164 (-10.93%) 93 85 -8 (-8.60%) tcp_retransmit_skb 1145 981 -164 (-14.32%) 67 59 -8 (-11.94%) tcp_retransmit_synack 1183 951 -232 (-19.61%) 67 55 -12 (-17.91%) bpf_tcptuner 1459 1187 -272 (-18.64%) 99 80 -19 (-19.19%) tw_egress 801 776 -25 (-3.12%) 69 66 -3 (-4.35%) tw_ingress 795 770 -25 (-3.14%) 69 66 -3 (-4.35%) ttls_tc_ingress 19025 19383 +358 (+1.88%) 470 465 -5 (-1.06%) ttls_nat_egress 490 299 -191 (-38.98%) 33 20 -13 (-39.39%) ttls_nat_ingress 448 285 -163 (-36.38%) 32 21 -11 (-34.38%) tw_twfw_egress 511127 212071 -299056 (-58.51%) 16733 8504 -8229 (-49.18%) tw_twfw_ingress 500095 212069 -288026 (-57.59%) 16223 8504 -7719 (-47.58%) tw_twfw_tc_eg 511113 212064 -299049 (-58.51%) 16732 8504 -8228 (-49.18%) tw_twfw_tc_in 500095 212069 -288026 (-57.59%) 16223 8504 -7719 (-47.58%) tw_twfw_egress 12632 12435 -197 (-1.56%) 276 260 -16 (-5.80%) tw_twfw_ingress 12631 12454 -177 (-1.40%) 278 261 -17 (-6.12%) tw_twfw_tc_eg 12595 12435 -160 (-1.27%) 274 259 -15 (-5.47%) tw_twfw_tc_in 12631 12454 -177 (-1.40%) 278 261 -17 (-6.12%) tw_xdp_dump 266 209 -57 (-21.43%) 9 8 -1 (-11.11%) CILIUM ========= File Program Insns (A) Insns (B) Insns (DIFF) States (A) States (B) States (DIFF) ------------- -------------------------------- --------- --------- ---------------- ---------- ---------- -------------- bpf_host.o cil_to_netdev 6047 4578 -1469 (-24.29%) 362 249 -113 (-31.22%) bpf_host.o handle_lxc_traffic 2227 1585 -642 (-28.83%) 156 103 -53 (-33.97%) bpf_host.o tail_handle_ipv4_from_netdev 2244 1458 -786 (-35.03%) 163 106 -57 (-34.97%) bpf_host.o tail_handle_nat_fwd_ipv4 21022 10479 -10543 (-50.15%) 1289 670 -619 (-48.02%) bpf_host.o tail_handle_nat_fwd_ipv6 15433 11375 -4058 (-26.29%) 905 643 -262 (-28.95%) bpf_host.o tail_ipv4_host_policy_ingress 2219 1367 -852 (-38.40%) 161 96 -65 (-40.37%) bpf_host.o tail_nodeport_nat_egress_ipv4 22460 19862 -2598 (-11.57%) 1469 1293 -176 (-11.98%) bpf_host.o tail_nodeport_nat_ingress_ipv4 5526 3534 -1992 (-36.05%) 366 243 -123 (-33.61%) bpf_host.o tail_nodeport_nat_ingress_ipv6 5132 4256 -876 (-17.07%) 241 219 -22 (-9.13%) bpf_host.o tail_nodeport_nat_ipv6_egress 3702 3542 -160 (-4.32%) 215 205 -10 (-4.65%) bpf_lxc.o tail_handle_nat_fwd_ipv4 21022 10479 -10543 (-50.15%) 1289 670 -619 (-48.02%) bpf_lxc.o tail_handle_nat_fwd_ipv6 15433 11375 -4058 (-26.29%) 905 643 -262 (-28.95%) bpf_lxc.o tail_ipv4_ct_egress 5073 3374 -1699 (-33.49%) 262 172 -90 (-34.35%) bpf_lxc.o tail_ipv4_ct_ingress 5093 3385 -1708 (-33.54%) 262 172 -90 (-34.35%) bpf_lxc.o tail_ipv4_ct_ingress_policy_only 5093 3385 -1708 (-33.54%) 262 172 -90 (-34.35%) bpf_lxc.o tail_ipv6_ct_egress 4593 3878 -715 (-15.57%) 194 151 -43 (-22.16%) bpf_lxc.o tail_ipv6_ct_ingress 4606 3891 -715 (-15.52%) 194 151 -43 (-22.16%) bpf_lxc.o tail_ipv6_ct_ingress_policy_only 4606 3891 -715 (-15.52%) 194 151 -43 (-22.16%) bpf_lxc.o tail_nodeport_nat_ingress_ipv4 5526 3534 -1992 (-36.05%) 366 243 -123 (-33.61%) bpf_lxc.o tail_nodeport_nat_ingress_ipv6 5132 4256 -876 (-17.07%) 241 219 -22 (-9.13%) bpf_overlay.o tail_handle_nat_fwd_ipv4 20524 10114 -10410 (-50.72%) 1271 638 -633 (-49.80%) bpf_overlay.o tail_nodeport_nat_egress_ipv4 22718 19490 -3228 (-14.21%) 1475 1275 -200 (-13.56%) bpf_overlay.o tail_nodeport_nat_ingress_ipv4 5526 3534 -1992 (-36.05%) 366 243 -123 (-33.61%) bpf_overlay.o tail_nodeport_nat_ingress_ipv6 5132 4256 -876 (-17.07%) 241 219 -22 (-9.13%) bpf_overlay.o tail_nodeport_nat_ipv6_egress 3638 3548 -90 (-2.47%) 209 203 -6 (-2.87%) bpf_overlay.o tail_rev_nodeport_lb4 4368 3820 -548 (-12.55%) 248 215 -33 (-13.31%) bpf_overlay.o tail_rev_nodeport_lb6 2867 2428 -439 (-15.31%) 167 140 -27 (-16.17%) bpf_sock.o cil_sock6_connect 1718 1703 -15 (-0.87%) 100 99 -1 (-1.00%) bpf_xdp.o tail_handle_nat_fwd_ipv4 12917 12443 -474 (-3.67%) 875 849 -26 (-2.97%) bpf_xdp.o tail_handle_nat_fwd_ipv6 13515 13264 -251 (-1.86%) 715 702 -13 (-1.82%) bpf_xdp.o tail_lb_ipv4 39492 36367 -3125 (-7.91%) 2430 2251 -179 (-7.37%) bpf_xdp.o tail_lb_ipv6 80441 78058 -2383 (-2.96%) 3647 3523 -124 (-3.40%) bpf_xdp.o tail_nodeport_ipv6_dsr 1038 901 -137 (-13.20%) 61 55 -6 (-9.84%) bpf_xdp.o tail_nodeport_nat_egress_ipv4 13027 12096 -931 (-7.15%) 868 809 -59 (-6.80%) bpf_xdp.o tail_nodeport_nat_ingress_ipv4 7617 5900 -1717 (-22.54%) 522 413 -109 (-20.88%) bpf_xdp.o tail_nodeport_nat_ingress_ipv6 7575 7395 -180 (-2.38%) 383 374 -9 (-2.35%) bpf_xdp.o tail_rev_nodeport_lb4 6808 6739 -69 (-1.01%) 403 396 -7 (-1.74%) bpf_xdp.o tail_rev_nodeport_lb6 16173 15847 -326 (-2.02%) 1010 990 -20 (-1.98%) Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231205184248.1502704-9-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 1ebe76c98451..e5ce530641ba 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4477,8 +4477,7 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, return err; mark_stack_slot_scratched(env, spi); - if (reg && !(off % BPF_REG_SIZE) && register_is_bounded(reg) && - !register_is_null(reg) && env->bpf_capable) { + if (reg && !(off % BPF_REG_SIZE) && register_is_bounded(reg) && env->bpf_capable) { save_register_state(env, state, spi, reg, size); /* Break the relation on a narrowing spill. */ if (fls64(reg->umax_value) > BITS_PER_BYTE * size) @@ -4527,7 +4526,12 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, /* when we zero initialize stack slots mark them as such */ if ((reg && register_is_null(reg)) || (!reg && is_bpf_st_mem(insn) && insn->imm == 0)) { - /* backtracking doesn't work for STACK_ZERO yet. */ + /* STACK_ZERO case happened because register spill + * wasn't properly aligned at the stack slot boundary, + * so it's not a register spill anymore; force + * originating register to be precise to make + * STACK_ZERO correct for subsequent states + */ err = mark_chain_precision(env, value_regno); if (err) return err; -- cgit v1.2.3 From 909fa05dd3c181e5b403912889057f7cdbf3906c Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 30 Nov 2023 10:52:13 -0800 Subject: bpf: align CAP_NET_ADMIN checks with bpf_capable() approach Within BPF syscall handling code CAP_NET_ADMIN checks stand out a bit compared to CAP_BPF and CAP_PERFMON checks. For the latter, CAP_BPF or CAP_PERFMON are checked first, but if they are not set, CAP_SYS_ADMIN takes over and grants whatever part of BPF syscall is required. Similar kind of checks that involve CAP_NET_ADMIN are not so consistent. One out of four uses does follow CAP_BPF/CAP_PERFMON model: during BPF_PROG_LOAD, if the type of BPF program is "network-related" either CAP_NET_ADMIN or CAP_SYS_ADMIN is required to proceed. But in three other cases CAP_NET_ADMIN is required even if CAP_SYS_ADMIN is set: - when creating DEVMAP/XDKMAP/CPU_MAP maps; - when attaching CGROUP_SKB programs; - when handling BPF_PROG_QUERY command. This patch is changing the latter three cases to follow BPF_PROG_LOAD model, that is allowing to proceed under either CAP_NET_ADMIN or CAP_SYS_ADMIN. This also makes it cleaner in subsequent BPF token patches to switch wholesomely to a generic bpf_token_capable(int cap) check, that always falls back to CAP_SYS_ADMIN if requested capability is missing. Cc: Jakub Kicinski Acked-by: Yafang Shao Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231130185229.2688956-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/syscall.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index ebaccf77d56e..ee33a52abf18 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1121,6 +1121,11 @@ free_map_tab: return ret; } +static bool bpf_net_capable(void) +{ + return capable(CAP_NET_ADMIN) || capable(CAP_SYS_ADMIN); +} + #define BPF_MAP_CREATE_LAST_FIELD map_extra /* called via syscall */ static int map_create(union bpf_attr *attr) @@ -1224,7 +1229,7 @@ static int map_create(union bpf_attr *attr) case BPF_MAP_TYPE_DEVMAP: case BPF_MAP_TYPE_DEVMAP_HASH: case BPF_MAP_TYPE_XSKMAP: - if (!capable(CAP_NET_ADMIN)) + if (!bpf_net_capable()) return -EPERM; break; default: @@ -2625,7 +2630,7 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) !bpf_capable()) return -EPERM; - if (is_net_admin_prog_type(type) && !capable(CAP_NET_ADMIN) && !capable(CAP_SYS_ADMIN)) + if (is_net_admin_prog_type(type) && !bpf_net_capable()) return -EPERM; if (is_perfmon_prog_type(type) && !perfmon_capable()) return -EPERM; @@ -3777,7 +3782,7 @@ static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog, case BPF_PROG_TYPE_SK_LOOKUP: return attach_type == prog->expected_attach_type ? 0 : -EINVAL; case BPF_PROG_TYPE_CGROUP_SKB: - if (!capable(CAP_NET_ADMIN)) + if (!bpf_net_capable()) /* cg-skb progs can be loaded by unpriv user. * check permissions at attach time. */ @@ -3980,7 +3985,7 @@ static int bpf_prog_detach(const union bpf_attr *attr) static int bpf_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr) { - if (!capable(CAP_NET_ADMIN)) + if (!bpf_net_capable()) return -EPERM; if (CHECK_ATTR(BPF_PROG_QUERY)) return -EINVAL; -- cgit v1.2.3 From 40bba140c60fbb3ee8df6203c82fbd3de9f19d95 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 30 Nov 2023 10:52:14 -0800 Subject: bpf: add BPF token delegation mount options to BPF FS Add few new mount options to BPF FS that allow to specify that a given BPF FS instance allows creation of BPF token (added in the next patch), and what sort of operations are allowed under BPF token. As such, we get 4 new mount options, each is a bit mask - `delegate_cmds` allow to specify which bpf() syscall commands are allowed with BPF token derived from this BPF FS instance; - if BPF_MAP_CREATE command is allowed, `delegate_maps` specifies a set of allowable BPF map types that could be created with BPF token; - if BPF_PROG_LOAD command is allowed, `delegate_progs` specifies a set of allowable BPF program types that could be loaded with BPF token; - if BPF_PROG_LOAD command is allowed, `delegate_attachs` specifies a set of allowable BPF program attach types that could be loaded with BPF token; delegate_progs and delegate_attachs are meant to be used together, as full BPF program type is, in general, determined through both program type and program attach type. Currently, these mount options accept the following forms of values: - a special value "any", that enables all possible values of a given bit set; - numeric value (decimal or hexadecimal, determined by kernel automatically) that specifies a bit mask value directly; - all the values for a given mount option are combined, if specified multiple times. E.g., `mount -t bpf nodev /path/to/mount -o delegate_maps=0x1 -o delegate_maps=0x2` will result in a combined 0x3 mask. Ideally, more convenient (for humans) symbolic form derived from corresponding UAPI enums would be accepted (e.g., `-o delegate_progs=kprobe|tracepoint`) and I intend to implement this, but it requires a bunch of UAPI header churn, so I postponed it until this feature lands upstream or at least there is a definite consensus that this feature is acceptable and is going to make it, just to minimize amount of wasted effort and not increase amount of non-essential code to be reviewed. Attentive reader will notice that BPF FS is now marked as FS_USERNS_MOUNT, which theoretically makes it mountable inside non-init user namespace as long as the process has sufficient *namespaced* capabilities within that user namespace. But in reality we still restrict BPF FS to be mountable only by processes with CAP_SYS_ADMIN *in init userns* (extra check in bpf_fill_super()). FS_USERNS_MOUNT is added to allow creating BPF FS context object (i.e., fsopen("bpf")) from inside unprivileged process inside non-init userns, to capture that userns as the owning userns. It will still be required to pass this context object back to privileged process to instantiate and mount it. This manipulation is important, because capturing non-init userns as the owning userns of BPF FS instance (super block) allows to use that userns to constraint BPF token to that userns later on (see next patch). So creating BPF FS with delegation inside unprivileged userns will restrict derived BPF token objects to only "work" inside that intended userns, making it scoped to a intended "container". Also, setting these delegation options requires capable(CAP_SYS_ADMIN), so unprivileged process cannot set this up without involvement of a privileged process. There is a set of selftests at the end of the patch set that simulates this sequence of steps and validates that everything works as intended. But careful review is requested to make sure there are no missed gaps in the implementation and testing. This somewhat subtle set of aspects is the result of previous discussions ([0]) about various user namespace implications and interactions with BPF token functionality and is necessary to contain BPF token inside intended user namespace. [0] https://lore.kernel.org/bpf/20230704-hochverdient-lehne-eeb9eeef785e@brauner/ Acked-by: Christian Brauner Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231130185229.2688956-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 10 ++++++ kernel/bpf/inode.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++------ 2 files changed, 88 insertions(+), 10 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 10e5e4d8a00f..d3c9acc593ea 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1581,6 +1581,16 @@ struct bpf_link_primer { u32 id; }; +struct bpf_mount_opts { + umode_t mode; + + /* BPF token-related delegation options */ + u64 delegate_cmds; + u64 delegate_maps; + u64 delegate_progs; + u64 delegate_attachs; +}; + struct bpf_struct_ops_value; struct btf_member; diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c index 1aafb2ff2e95..220fe0f99095 100644 --- a/kernel/bpf/inode.c +++ b/kernel/bpf/inode.c @@ -20,6 +20,7 @@ #include #include #include +#include #include "preload/bpf_preload.h" enum bpf_type { @@ -599,10 +600,31 @@ EXPORT_SYMBOL(bpf_prog_get_type_path); */ static int bpf_show_options(struct seq_file *m, struct dentry *root) { + struct bpf_mount_opts *opts = root->d_sb->s_fs_info; umode_t mode = d_inode(root)->i_mode & S_IALLUGO & ~S_ISVTX; if (mode != S_IRWXUGO) seq_printf(m, ",mode=%o", mode); + + if (opts->delegate_cmds == ~0ULL) + seq_printf(m, ",delegate_cmds=any"); + else if (opts->delegate_cmds) + seq_printf(m, ",delegate_cmds=0x%llx", opts->delegate_cmds); + + if (opts->delegate_maps == ~0ULL) + seq_printf(m, ",delegate_maps=any"); + else if (opts->delegate_maps) + seq_printf(m, ",delegate_maps=0x%llx", opts->delegate_maps); + + if (opts->delegate_progs == ~0ULL) + seq_printf(m, ",delegate_progs=any"); + else if (opts->delegate_progs) + seq_printf(m, ",delegate_progs=0x%llx", opts->delegate_progs); + + if (opts->delegate_attachs == ~0ULL) + seq_printf(m, ",delegate_attachs=any"); + else if (opts->delegate_attachs) + seq_printf(m, ",delegate_attachs=0x%llx", opts->delegate_attachs); return 0; } @@ -626,22 +648,27 @@ static const struct super_operations bpf_super_ops = { enum { OPT_MODE, + OPT_DELEGATE_CMDS, + OPT_DELEGATE_MAPS, + OPT_DELEGATE_PROGS, + OPT_DELEGATE_ATTACHS, }; static const struct fs_parameter_spec bpf_fs_parameters[] = { fsparam_u32oct ("mode", OPT_MODE), + fsparam_string ("delegate_cmds", OPT_DELEGATE_CMDS), + fsparam_string ("delegate_maps", OPT_DELEGATE_MAPS), + fsparam_string ("delegate_progs", OPT_DELEGATE_PROGS), + fsparam_string ("delegate_attachs", OPT_DELEGATE_ATTACHS), {} }; -struct bpf_mount_opts { - umode_t mode; -}; - static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param) { - struct bpf_mount_opts *opts = fc->fs_private; + struct bpf_mount_opts *opts = fc->s_fs_info; struct fs_parse_result result; - int opt; + int opt, err; + u64 msk; opt = fs_parse(fc, bpf_fs_parameters, param, &result); if (opt < 0) { @@ -665,6 +692,28 @@ static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param) case OPT_MODE: opts->mode = result.uint_32 & S_IALLUGO; break; + case OPT_DELEGATE_CMDS: + case OPT_DELEGATE_MAPS: + case OPT_DELEGATE_PROGS: + case OPT_DELEGATE_ATTACHS: + if (strcmp(param->string, "any") == 0) { + msk = ~0ULL; + } else { + err = kstrtou64(param->string, 0, &msk); + if (err) + return err; + } + /* Setting delegation mount options requires privileges */ + if (msk && !capable(CAP_SYS_ADMIN)) + return -EPERM; + switch (opt) { + case OPT_DELEGATE_CMDS: opts->delegate_cmds |= msk; break; + case OPT_DELEGATE_MAPS: opts->delegate_maps |= msk; break; + case OPT_DELEGATE_PROGS: opts->delegate_progs |= msk; break; + case OPT_DELEGATE_ATTACHS: opts->delegate_attachs |= msk; break; + default: return -EINVAL; + } + break; } return 0; @@ -739,10 +788,14 @@ out: static int bpf_fill_super(struct super_block *sb, struct fs_context *fc) { static const struct tree_descr bpf_rfiles[] = { { "" } }; - struct bpf_mount_opts *opts = fc->fs_private; + struct bpf_mount_opts *opts = sb->s_fs_info; struct inode *inode; int ret; + /* Mounting an instance of BPF FS requires privileges */ + if (fc->user_ns != &init_user_ns && !capable(CAP_SYS_ADMIN)) + return -EPERM; + ret = simple_fill_super(sb, BPF_FS_MAGIC, bpf_rfiles); if (ret) return ret; @@ -764,7 +817,7 @@ static int bpf_get_tree(struct fs_context *fc) static void bpf_free_fc(struct fs_context *fc) { - kfree(fc->fs_private); + kfree(fc->s_fs_info); } static const struct fs_context_operations bpf_context_ops = { @@ -786,17 +839,32 @@ static int bpf_init_fs_context(struct fs_context *fc) opts->mode = S_IRWXUGO; - fc->fs_private = opts; + /* start out with no BPF token delegation enabled */ + opts->delegate_cmds = 0; + opts->delegate_maps = 0; + opts->delegate_progs = 0; + opts->delegate_attachs = 0; + + fc->s_fs_info = opts; fc->ops = &bpf_context_ops; return 0; } +static void bpf_kill_super(struct super_block *sb) +{ + struct bpf_mount_opts *opts = sb->s_fs_info; + + kill_litter_super(sb); + kfree(opts); +} + static struct file_system_type bpf_fs_type = { .owner = THIS_MODULE, .name = "bpf", .init_fs_context = bpf_init_fs_context, .parameters = bpf_fs_parameters, - .kill_sb = kill_litter_super, + .kill_sb = bpf_kill_super, + .fs_flags = FS_USERNS_MOUNT, }; static int __init bpf_init(void) -- cgit v1.2.3 From 4527358b76861dfd64ee34aba45d81648fbc8a61 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 30 Nov 2023 10:52:15 -0800 Subject: bpf: introduce BPF token object Add new kind of BPF kernel object, BPF token. BPF token is meant to allow delegating privileged BPF functionality, like loading a BPF program or creating a BPF map, from privileged process to a *trusted* unprivileged process, all while having a good amount of control over which privileged operations could be performed using provided BPF token. This is achieved through mounting BPF FS instance with extra delegation mount options, which determine what operations are delegatable, and also constraining it to the owning user namespace (as mentioned in the previous patch). BPF token itself is just a derivative from BPF FS and can be created through a new bpf() syscall command, BPF_TOKEN_CREATE, which accepts BPF FS FD, which can be attained through open() API by opening BPF FS mount point. Currently, BPF token "inherits" delegated command, map types, prog type, and attach type bit sets from BPF FS as is. In the future, having an BPF token as a separate object with its own FD, we can allow to further restrict BPF token's allowable set of things either at the creation time or after the fact, allowing the process to guard itself further from unintentionally trying to load undesired kind of BPF programs. But for now we keep things simple and just copy bit sets as is. When BPF token is created from BPF FS mount, we take reference to the BPF super block's owning user namespace, and then use that namespace for checking all the {CAP_BPF, CAP_PERFMON, CAP_NET_ADMIN, CAP_SYS_ADMIN} capabilities that are normally only checked against init userns (using capable()), but now we check them using ns_capable() instead (if BPF token is provided). See bpf_token_capable() for details. Such setup means that BPF token in itself is not sufficient to grant BPF functionality. User namespaced process has to *also* have necessary combination of capabilities inside that user namespace. So while previously CAP_BPF was useless when granted within user namespace, now it gains a meaning and allows container managers and sys admins to have a flexible control over which processes can and need to use BPF functionality within the user namespace (i.e., container in practice). And BPF FS delegation mount options and derived BPF tokens serve as a per-container "flag" to grant overall ability to use bpf() (plus further restrict on which parts of bpf() syscalls are treated as namespaced). Note also, BPF_TOKEN_CREATE command itself requires ns_capable(CAP_BPF) within the BPF FS owning user namespace, rounding up the ns_capable() story of BPF token. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231130185229.2688956-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 41 ++++++++ include/uapi/linux/bpf.h | 37 +++++++ kernel/bpf/Makefile | 2 +- kernel/bpf/inode.c | 12 ++- kernel/bpf/syscall.c | 17 ++++ kernel/bpf/token.c | 214 +++++++++++++++++++++++++++++++++++++++++ tools/include/uapi/linux/bpf.h | 37 +++++++ 7 files changed, 354 insertions(+), 6 deletions(-) create mode 100644 kernel/bpf/token.c (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index d3c9acc593ea..aa9cf8e5fab1 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -51,6 +51,10 @@ struct module; struct bpf_func_state; struct ftrace_ops; struct cgroup; +struct bpf_token; +struct user_namespace; +struct super_block; +struct inode; extern struct idr btf_idr; extern spinlock_t btf_idr_lock; @@ -1591,6 +1595,13 @@ struct bpf_mount_opts { u64 delegate_attachs; }; +struct bpf_token { + struct work_struct work; + atomic64_t refcnt; + struct user_namespace *userns; + u64 allowed_cmds; +}; + struct bpf_struct_ops_value; struct btf_member; @@ -2048,6 +2059,7 @@ static inline void bpf_enable_instrumentation(void) migrate_enable(); } +extern const struct super_operations bpf_super_ops; extern const struct file_operations bpf_map_fops; extern const struct file_operations bpf_prog_fops; extern const struct file_operations bpf_iter_fops; @@ -2182,6 +2194,8 @@ static inline void bpf_map_dec_elem_count(struct bpf_map *map) extern int sysctl_unprivileged_bpf_disabled; +bool bpf_token_capable(const struct bpf_token *token, int cap); + static inline bool bpf_allow_ptr_leaks(void) { return perfmon_capable(); @@ -2216,8 +2230,17 @@ int bpf_link_new_fd(struct bpf_link *link); struct bpf_link *bpf_link_get_from_fd(u32 ufd); struct bpf_link *bpf_link_get_curr_or_next(u32 *id); +void bpf_token_inc(struct bpf_token *token); +void bpf_token_put(struct bpf_token *token); +int bpf_token_create(union bpf_attr *attr); +struct bpf_token *bpf_token_get_from_fd(u32 ufd); + +bool bpf_token_allow_cmd(const struct bpf_token *token, enum bpf_cmd cmd); + int bpf_obj_pin_user(u32 ufd, int path_fd, const char __user *pathname); int bpf_obj_get_user(int path_fd, const char __user *pathname, int flags); +struct inode *bpf_get_inode(struct super_block *sb, const struct inode *dir, + umode_t mode); #define BPF_ITER_FUNC_PREFIX "bpf_iter_" #define DEFINE_BPF_ITER_FUNC(target, args...) \ @@ -2580,6 +2603,24 @@ static inline int bpf_obj_get_user(const char __user *pathname, int flags) return -EOPNOTSUPP; } +static inline bool bpf_token_capable(const struct bpf_token *token, int cap) +{ + return capable(cap) || (cap != CAP_SYS_ADMIN && capable(CAP_SYS_ADMIN)); +} + +static inline void bpf_token_inc(struct bpf_token *token) +{ +} + +static inline void bpf_token_put(struct bpf_token *token) +{ +} + +static inline struct bpf_token *bpf_token_get_from_fd(u32 ufd) +{ + return ERR_PTR(-EOPNOTSUPP); +} + static inline void __dev_flush(void) { } diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index e88746ba7d21..d4a567e5bc3c 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -847,6 +847,36 @@ union bpf_iter_link_info { * Returns zero on success. On error, -1 is returned and *errno* * is set appropriately. * + * BPF_TOKEN_CREATE + * Description + * Create BPF token with embedded information about what + * BPF-related functionality it allows: + * - a set of allowed bpf() syscall commands; + * - a set of allowed BPF map types to be created with + * BPF_MAP_CREATE command, if BPF_MAP_CREATE itself is allowed; + * - a set of allowed BPF program types and BPF program attach + * types to be loaded with BPF_PROG_LOAD command, if + * BPF_PROG_LOAD itself is allowed. + * + * BPF token is created (derived) from an instance of BPF FS, + * assuming it has necessary delegation mount options specified. + * This BPF token can be passed as an extra parameter to various + * bpf() syscall commands to grant BPF subsystem functionality to + * unprivileged processes. + * + * When created, BPF token is "associated" with the owning + * user namespace of BPF FS instance (super block) that it was + * derived from, and subsequent BPF operations performed with + * BPF token would be performing capabilities checks (i.e., + * CAP_BPF, CAP_PERFMON, CAP_NET_ADMIN, CAP_SYS_ADMIN) within + * that user namespace. Without BPF token, such capabilities + * have to be granted in init user namespace, making bpf() + * syscall incompatible with user namespace, for the most part. + * + * Return + * A new file descriptor (a nonnegative integer), or -1 if an + * error occurred (in which case, *errno* is set appropriately). + * * NOTES * eBPF objects (maps and programs) can be shared between processes. * @@ -901,6 +931,8 @@ enum bpf_cmd { BPF_ITER_CREATE, BPF_LINK_DETACH, BPF_PROG_BIND_MAP, + BPF_TOKEN_CREATE, + __MAX_BPF_CMD, }; enum bpf_map_type { @@ -1712,6 +1744,11 @@ union bpf_attr { __u32 flags; /* extra flags */ } prog_bind_map; + struct { /* struct used by BPF_TOKEN_CREATE command */ + __u32 flags; + __u32 bpffs_fd; + } token_create; + } __attribute__((aligned(8))); /* The description below is an attempt at providing documentation to eBPF diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile index f526b7573e97..4ce95acfcaa7 100644 --- a/kernel/bpf/Makefile +++ b/kernel/bpf/Makefile @@ -6,7 +6,7 @@ cflags-nogcse-$(CONFIG_X86)$(CONFIG_CC_IS_GCC) := -fno-gcse endif CFLAGS_core.o += $(call cc-disable-warning, override-init) $(cflags-nogcse-yy) -obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o log.o +obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o log.o token.o obj-$(CONFIG_BPF_SYSCALL) += bpf_iter.o map_iter.o task_iter.o prog_iter.o link_iter.o obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o lpm_trie.o map_in_map.o bloom_filter.o obj-$(CONFIG_BPF_SYSCALL) += local_storage.o queue_stack_maps.o ringbuf.o diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c index 220fe0f99095..6ce3f9696e72 100644 --- a/kernel/bpf/inode.c +++ b/kernel/bpf/inode.c @@ -99,9 +99,9 @@ static const struct inode_operations bpf_prog_iops = { }; static const struct inode_operations bpf_map_iops = { }; static const struct inode_operations bpf_link_iops = { }; -static struct inode *bpf_get_inode(struct super_block *sb, - const struct inode *dir, - umode_t mode) +struct inode *bpf_get_inode(struct super_block *sb, + const struct inode *dir, + umode_t mode) { struct inode *inode; @@ -602,11 +602,13 @@ static int bpf_show_options(struct seq_file *m, struct dentry *root) { struct bpf_mount_opts *opts = root->d_sb->s_fs_info; umode_t mode = d_inode(root)->i_mode & S_IALLUGO & ~S_ISVTX; + u64 mask; if (mode != S_IRWXUGO) seq_printf(m, ",mode=%o", mode); - if (opts->delegate_cmds == ~0ULL) + mask = (1ULL << __MAX_BPF_CMD) - 1; + if ((opts->delegate_cmds & mask) == mask) seq_printf(m, ",delegate_cmds=any"); else if (opts->delegate_cmds) seq_printf(m, ",delegate_cmds=0x%llx", opts->delegate_cmds); @@ -639,7 +641,7 @@ static void bpf_free_inode(struct inode *inode) free_inode_nonrcu(inode); } -static const struct super_operations bpf_super_ops = { +const struct super_operations bpf_super_ops = { .statfs = simple_statfs, .drop_inode = generic_delete_inode, .show_options = bpf_show_options, diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index ee33a52abf18..a156d549b356 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -5377,6 +5377,20 @@ out_prog_put: return ret; } +#define BPF_TOKEN_CREATE_LAST_FIELD token_create.bpffs_fd + +static int token_create(union bpf_attr *attr) +{ + if (CHECK_ATTR(BPF_TOKEN_CREATE)) + return -EINVAL; + + /* no flags are supported yet */ + if (attr->token_create.flags) + return -EINVAL; + + return bpf_token_create(attr); +} + static int __sys_bpf(int cmd, bpfptr_t uattr, unsigned int size) { union bpf_attr attr; @@ -5510,6 +5524,9 @@ static int __sys_bpf(int cmd, bpfptr_t uattr, unsigned int size) case BPF_PROG_BIND_MAP: err = bpf_prog_bind_map(&attr); break; + case BPF_TOKEN_CREATE: + err = token_create(&attr); + break; default: err = -EINVAL; break; diff --git a/kernel/bpf/token.c b/kernel/bpf/token.c new file mode 100644 index 000000000000..e18aaecc67e9 --- /dev/null +++ b/kernel/bpf/token.c @@ -0,0 +1,214 @@ +#include +#include +#include +#include +#include +#include +#include +#include +#include + +bool bpf_token_capable(const struct bpf_token *token, int cap) +{ + /* BPF token allows ns_capable() level of capabilities, but only if + * token's userns is *exactly* the same as current user's userns + */ + if (token && current_user_ns() == token->userns) { + if (ns_capable(token->userns, cap)) + return true; + if (cap != CAP_SYS_ADMIN && ns_capable(token->userns, CAP_SYS_ADMIN)) + return true; + } + /* otherwise fallback to capable() checks */ + return capable(cap) || (cap != CAP_SYS_ADMIN && capable(CAP_SYS_ADMIN)); +} + +void bpf_token_inc(struct bpf_token *token) +{ + atomic64_inc(&token->refcnt); +} + +static void bpf_token_free(struct bpf_token *token) +{ + put_user_ns(token->userns); + kvfree(token); +} + +static void bpf_token_put_deferred(struct work_struct *work) +{ + struct bpf_token *token = container_of(work, struct bpf_token, work); + + bpf_token_free(token); +} + +void bpf_token_put(struct bpf_token *token) +{ + if (!token) + return; + + if (!atomic64_dec_and_test(&token->refcnt)) + return; + + INIT_WORK(&token->work, bpf_token_put_deferred); + schedule_work(&token->work); +} + +static int bpf_token_release(struct inode *inode, struct file *filp) +{ + struct bpf_token *token = filp->private_data; + + bpf_token_put(token); + return 0; +} + +static void bpf_token_show_fdinfo(struct seq_file *m, struct file *filp) +{ + struct bpf_token *token = filp->private_data; + u64 mask; + + BUILD_BUG_ON(__MAX_BPF_CMD >= 64); + mask = (1ULL << __MAX_BPF_CMD) - 1; + if ((token->allowed_cmds & mask) == mask) + seq_printf(m, "allowed_cmds:\tany\n"); + else + seq_printf(m, "allowed_cmds:\t0x%llx\n", token->allowed_cmds); +} + +#define BPF_TOKEN_INODE_NAME "bpf-token" + +static const struct inode_operations bpf_token_iops = { }; + +static const struct file_operations bpf_token_fops = { + .release = bpf_token_release, + .show_fdinfo = bpf_token_show_fdinfo, +}; + +int bpf_token_create(union bpf_attr *attr) +{ + struct bpf_mount_opts *mnt_opts; + struct bpf_token *token = NULL; + struct user_namespace *userns; + struct inode *inode; + struct file *file; + struct path path; + struct fd f; + umode_t mode; + int err, fd; + + f = fdget(attr->token_create.bpffs_fd); + if (!f.file) + return -EBADF; + + path = f.file->f_path; + path_get(&path); + fdput(f); + + if (path.dentry != path.mnt->mnt_sb->s_root) { + err = -EINVAL; + goto out_path; + } + if (path.mnt->mnt_sb->s_op != &bpf_super_ops) { + err = -EINVAL; + goto out_path; + } + err = path_permission(&path, MAY_ACCESS); + if (err) + goto out_path; + + userns = path.dentry->d_sb->s_user_ns; + /* + * Enforce that creators of BPF tokens are in the same user + * namespace as the BPF FS instance. This makes reasoning about + * permissions a lot easier and we can always relax this later. + */ + if (current_user_ns() != userns) { + err = -EPERM; + goto out_path; + } + if (!ns_capable(userns, CAP_BPF)) { + err = -EPERM; + goto out_path; + } + + mode = S_IFREG | ((S_IRUSR | S_IWUSR) & ~current_umask()); + inode = bpf_get_inode(path.mnt->mnt_sb, NULL, mode); + if (IS_ERR(inode)) { + err = PTR_ERR(inode); + goto out_path; + } + + inode->i_op = &bpf_token_iops; + inode->i_fop = &bpf_token_fops; + clear_nlink(inode); /* make sure it is unlinked */ + + file = alloc_file_pseudo(inode, path.mnt, BPF_TOKEN_INODE_NAME, O_RDWR, &bpf_token_fops); + if (IS_ERR(file)) { + iput(inode); + err = PTR_ERR(file); + goto out_path; + } + + token = kvzalloc(sizeof(*token), GFP_USER); + if (!token) { + err = -ENOMEM; + goto out_file; + } + + atomic64_set(&token->refcnt, 1); + + /* remember bpffs owning userns for future ns_capable() checks */ + token->userns = get_user_ns(userns); + + mnt_opts = path.dentry->d_sb->s_fs_info; + token->allowed_cmds = mnt_opts->delegate_cmds; + + fd = get_unused_fd_flags(O_CLOEXEC); + if (fd < 0) { + err = fd; + goto out_token; + } + + file->private_data = token; + fd_install(fd, file); + + path_put(&path); + return fd; + +out_token: + bpf_token_free(token); +out_file: + fput(file); +out_path: + path_put(&path); + return err; +} + +struct bpf_token *bpf_token_get_from_fd(u32 ufd) +{ + struct fd f = fdget(ufd); + struct bpf_token *token; + + if (!f.file) + return ERR_PTR(-EBADF); + if (f.file->f_op != &bpf_token_fops) { + fdput(f); + return ERR_PTR(-EINVAL); + } + + token = f.file->private_data; + bpf_token_inc(token); + fdput(f); + + return token; +} + +bool bpf_token_allow_cmd(const struct bpf_token *token, enum bpf_cmd cmd) +{ + /* BPF token can be used only within exactly the same userns in which + * it was created + */ + if (!token || current_user_ns() != token->userns) + return false; + + return token->allowed_cmds & (1ULL << cmd); +} diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index e88746ba7d21..d4a567e5bc3c 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -847,6 +847,36 @@ union bpf_iter_link_info { * Returns zero on success. On error, -1 is returned and *errno* * is set appropriately. * + * BPF_TOKEN_CREATE + * Description + * Create BPF token with embedded information about what + * BPF-related functionality it allows: + * - a set of allowed bpf() syscall commands; + * - a set of allowed BPF map types to be created with + * BPF_MAP_CREATE command, if BPF_MAP_CREATE itself is allowed; + * - a set of allowed BPF program types and BPF program attach + * types to be loaded with BPF_PROG_LOAD command, if + * BPF_PROG_LOAD itself is allowed. + * + * BPF token is created (derived) from an instance of BPF FS, + * assuming it has necessary delegation mount options specified. + * This BPF token can be passed as an extra parameter to various + * bpf() syscall commands to grant BPF subsystem functionality to + * unprivileged processes. + * + * When created, BPF token is "associated" with the owning + * user namespace of BPF FS instance (super block) that it was + * derived from, and subsequent BPF operations performed with + * BPF token would be performing capabilities checks (i.e., + * CAP_BPF, CAP_PERFMON, CAP_NET_ADMIN, CAP_SYS_ADMIN) within + * that user namespace. Without BPF token, such capabilities + * have to be granted in init user namespace, making bpf() + * syscall incompatible with user namespace, for the most part. + * + * Return + * A new file descriptor (a nonnegative integer), or -1 if an + * error occurred (in which case, *errno* is set appropriately). + * * NOTES * eBPF objects (maps and programs) can be shared between processes. * @@ -901,6 +931,8 @@ enum bpf_cmd { BPF_ITER_CREATE, BPF_LINK_DETACH, BPF_PROG_BIND_MAP, + BPF_TOKEN_CREATE, + __MAX_BPF_CMD, }; enum bpf_map_type { @@ -1712,6 +1744,11 @@ union bpf_attr { __u32 flags; /* extra flags */ } prog_bind_map; + struct { /* struct used by BPF_TOKEN_CREATE command */ + __u32 flags; + __u32 bpffs_fd; + } token_create; + } __attribute__((aligned(8))); /* The description below is an attempt at providing documentation to eBPF -- cgit v1.2.3 From 688b7270b3cb75e8ac78123d719967db40336e5b Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 30 Nov 2023 10:52:16 -0800 Subject: bpf: add BPF token support to BPF_MAP_CREATE command Allow providing token_fd for BPF_MAP_CREATE command to allow controlled BPF map creation from unprivileged process through delegated BPF token. Wire through a set of allowed BPF map types to BPF token, derived from BPF FS at BPF token creation time. This, in combination with allowed_cmds allows to create a narrowly-focused BPF token (controlled by privileged agent) with a restrictive set of BPF maps that application can attempt to create. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231130185229.2688956-5-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 2 + include/uapi/linux/bpf.h | 2 + kernel/bpf/inode.c | 3 +- kernel/bpf/syscall.c | 52 ++++++++++++++++------ kernel/bpf/token.c | 16 +++++++ tools/include/uapi/linux/bpf.h | 2 + .../selftests/bpf/prog_tests/libbpf_probes.c | 2 + .../testing/selftests/bpf/prog_tests/libbpf_str.c | 3 ++ 8 files changed, 67 insertions(+), 15 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index aa9cf8e5fab1..e08e8436df38 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1600,6 +1600,7 @@ struct bpf_token { atomic64_t refcnt; struct user_namespace *userns; u64 allowed_cmds; + u64 allowed_maps; }; struct bpf_struct_ops_value; @@ -2236,6 +2237,7 @@ int bpf_token_create(union bpf_attr *attr); struct bpf_token *bpf_token_get_from_fd(u32 ufd); bool bpf_token_allow_cmd(const struct bpf_token *token, enum bpf_cmd cmd); +bool bpf_token_allow_map_type(const struct bpf_token *token, enum bpf_map_type type); int bpf_obj_pin_user(u32 ufd, int path_fd, const char __user *pathname); int bpf_obj_get_user(int path_fd, const char __user *pathname, int flags); diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index d4a567e5bc3c..0bba3392b17a 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -983,6 +983,7 @@ enum bpf_map_type { BPF_MAP_TYPE_BLOOM_FILTER, BPF_MAP_TYPE_USER_RINGBUF, BPF_MAP_TYPE_CGRP_STORAGE, + __MAX_BPF_MAP_TYPE }; /* Note that tracing related programs such as @@ -1433,6 +1434,7 @@ union bpf_attr { * to using 5 hash functions). */ __u64 map_extra; + __u32 map_token_fd; }; struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */ diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c index 6ce3f9696e72..9c7865d1c53d 100644 --- a/kernel/bpf/inode.c +++ b/kernel/bpf/inode.c @@ -613,7 +613,8 @@ static int bpf_show_options(struct seq_file *m, struct dentry *root) else if (opts->delegate_cmds) seq_printf(m, ",delegate_cmds=0x%llx", opts->delegate_cmds); - if (opts->delegate_maps == ~0ULL) + mask = (1ULL << __MAX_BPF_MAP_TYPE) - 1; + if ((opts->delegate_maps & mask) == mask) seq_printf(m, ",delegate_maps=any"); else if (opts->delegate_maps) seq_printf(m, ",delegate_maps=0x%llx", opts->delegate_maps); diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index a156d549b356..22e14124cd61 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1009,8 +1009,8 @@ int map_check_no_btf(const struct bpf_map *map, return -ENOTSUPP; } -static int map_check_btf(struct bpf_map *map, const struct btf *btf, - u32 btf_key_id, u32 btf_value_id) +static int map_check_btf(struct bpf_map *map, struct bpf_token *token, + const struct btf *btf, u32 btf_key_id, u32 btf_value_id) { const struct btf_type *key_type, *value_type; u32 key_size, value_size; @@ -1038,7 +1038,7 @@ static int map_check_btf(struct bpf_map *map, const struct btf *btf, if (!IS_ERR_OR_NULL(map->record)) { int i; - if (!bpf_capable()) { + if (!bpf_token_capable(token, CAP_BPF)) { ret = -EPERM; goto free_map_tab; } @@ -1126,11 +1126,12 @@ static bool bpf_net_capable(void) return capable(CAP_NET_ADMIN) || capable(CAP_SYS_ADMIN); } -#define BPF_MAP_CREATE_LAST_FIELD map_extra +#define BPF_MAP_CREATE_LAST_FIELD map_token_fd /* called via syscall */ static int map_create(union bpf_attr *attr) { const struct bpf_map_ops *ops; + struct bpf_token *token = NULL; int numa_node = bpf_map_attr_numa_node(attr); u32 map_type = attr->map_type; struct bpf_map *map; @@ -1181,14 +1182,32 @@ static int map_create(union bpf_attr *attr) if (!ops->map_mem_usage) return -EINVAL; + if (attr->map_token_fd) { + token = bpf_token_get_from_fd(attr->map_token_fd); + if (IS_ERR(token)) + return PTR_ERR(token); + + /* if current token doesn't grant map creation permissions, + * then we can't use this token, so ignore it and rely on + * system-wide capabilities checks + */ + if (!bpf_token_allow_cmd(token, BPF_MAP_CREATE) || + !bpf_token_allow_map_type(token, attr->map_type)) { + bpf_token_put(token); + token = NULL; + } + } + + err = -EPERM; + /* Intent here is for unprivileged_bpf_disabled to block BPF map * creation for unprivileged users; other actions depend * on fd availability and access to bpffs, so are dependent on * object creation success. Even with unprivileged BPF disabled, * capability checks are still carried out. */ - if (sysctl_unprivileged_bpf_disabled && !bpf_capable()) - return -EPERM; + if (sysctl_unprivileged_bpf_disabled && !bpf_token_capable(token, CAP_BPF)) + goto put_token; /* check privileged map type permissions */ switch (map_type) { @@ -1221,25 +1240,27 @@ static int map_create(union bpf_attr *attr) case BPF_MAP_TYPE_LRU_PERCPU_HASH: case BPF_MAP_TYPE_STRUCT_OPS: case BPF_MAP_TYPE_CPUMAP: - if (!bpf_capable()) - return -EPERM; + if (!bpf_token_capable(token, CAP_BPF)) + goto put_token; break; case BPF_MAP_TYPE_SOCKMAP: case BPF_MAP_TYPE_SOCKHASH: case BPF_MAP_TYPE_DEVMAP: case BPF_MAP_TYPE_DEVMAP_HASH: case BPF_MAP_TYPE_XSKMAP: - if (!bpf_net_capable()) - return -EPERM; + if (!bpf_token_capable(token, CAP_NET_ADMIN)) + goto put_token; break; default: WARN(1, "unsupported map type %d", map_type); - return -EPERM; + goto put_token; } map = ops->map_alloc(attr); - if (IS_ERR(map)) - return PTR_ERR(map); + if (IS_ERR(map)) { + err = PTR_ERR(map); + goto put_token; + } map->ops = ops; map->map_type = map_type; @@ -1276,7 +1297,7 @@ static int map_create(union bpf_attr *attr) map->btf = btf; if (attr->btf_value_type_id) { - err = map_check_btf(map, btf, attr->btf_key_type_id, + err = map_check_btf(map, token, btf, attr->btf_key_type_id, attr->btf_value_type_id); if (err) goto free_map; @@ -1297,6 +1318,7 @@ static int map_create(union bpf_attr *attr) goto free_map_sec; bpf_map_save_memcg(map); + bpf_token_put(token); err = bpf_map_new_fd(map, f_flags); if (err < 0) { @@ -1317,6 +1339,8 @@ free_map_sec: free_map: btf_put(map->btf); map->ops->map_free(map); +put_token: + bpf_token_put(token); return err; } diff --git a/kernel/bpf/token.c b/kernel/bpf/token.c index e18aaecc67e9..06c34dae658e 100644 --- a/kernel/bpf/token.c +++ b/kernel/bpf/token.c @@ -72,6 +72,13 @@ static void bpf_token_show_fdinfo(struct seq_file *m, struct file *filp) seq_printf(m, "allowed_cmds:\tany\n"); else seq_printf(m, "allowed_cmds:\t0x%llx\n", token->allowed_cmds); + + BUILD_BUG_ON(__MAX_BPF_MAP_TYPE >= 64); + mask = (1ULL << __MAX_BPF_MAP_TYPE) - 1; + if ((token->allowed_maps & mask) == mask) + seq_printf(m, "allowed_maps:\tany\n"); + else + seq_printf(m, "allowed_maps:\t0x%llx\n", token->allowed_maps); } #define BPF_TOKEN_INODE_NAME "bpf-token" @@ -161,6 +168,7 @@ int bpf_token_create(union bpf_attr *attr) mnt_opts = path.dentry->d_sb->s_fs_info; token->allowed_cmds = mnt_opts->delegate_cmds; + token->allowed_maps = mnt_opts->delegate_maps; fd = get_unused_fd_flags(O_CLOEXEC); if (fd < 0) { @@ -212,3 +220,11 @@ bool bpf_token_allow_cmd(const struct bpf_token *token, enum bpf_cmd cmd) return token->allowed_cmds & (1ULL << cmd); } + +bool bpf_token_allow_map_type(const struct bpf_token *token, enum bpf_map_type type) +{ + if (!token || type >= __MAX_BPF_MAP_TYPE) + return false; + + return token->allowed_maps & (1ULL << type); +} diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index d4a567e5bc3c..0bba3392b17a 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -983,6 +983,7 @@ enum bpf_map_type { BPF_MAP_TYPE_BLOOM_FILTER, BPF_MAP_TYPE_USER_RINGBUF, BPF_MAP_TYPE_CGRP_STORAGE, + __MAX_BPF_MAP_TYPE }; /* Note that tracing related programs such as @@ -1433,6 +1434,7 @@ union bpf_attr { * to using 5 hash functions). */ __u64 map_extra; + __u32 map_token_fd; }; struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */ diff --git a/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c b/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c index 9f766ddd946a..573249a2814d 100644 --- a/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c +++ b/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c @@ -68,6 +68,8 @@ void test_libbpf_probe_map_types(void) if (map_type == BPF_MAP_TYPE_UNSPEC) continue; + if (strcmp(map_type_name, "__MAX_BPF_MAP_TYPE") == 0) + continue; if (!test__start_subtest(map_type_name)) continue; diff --git a/tools/testing/selftests/bpf/prog_tests/libbpf_str.c b/tools/testing/selftests/bpf/prog_tests/libbpf_str.c index c440ea3311ed..2a0633f43c73 100644 --- a/tools/testing/selftests/bpf/prog_tests/libbpf_str.c +++ b/tools/testing/selftests/bpf/prog_tests/libbpf_str.c @@ -132,6 +132,9 @@ static void test_libbpf_bpf_map_type_str(void) const char *map_type_str; char buf[256]; + if (map_type == __MAX_BPF_MAP_TYPE) + continue; + map_type_name = btf__str_by_offset(btf, e->name_off); map_type_str = libbpf_bpf_map_type_str(map_type); ASSERT_OK_PTR(map_type_str, map_type_name); -- cgit v1.2.3 From ee54b1a910e4d49c9a104f31ae3f5b979131adf8 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 30 Nov 2023 10:52:17 -0800 Subject: bpf: add BPF token support to BPF_BTF_LOAD command Accept BPF token FD in BPF_BTF_LOAD command to allow BTF data loading through delegated BPF token. BTF loading is a pretty straightforward operation, so as long as BPF token is created with allow_cmds granting BPF_BTF_LOAD command, kernel proceeds to parsing BTF data and creating BTF object. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231130185229.2688956-6-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/uapi/linux/bpf.h | 1 + kernel/bpf/syscall.c | 20 ++++++++++++++++++-- tools/include/uapi/linux/bpf.h | 1 + 3 files changed, 20 insertions(+), 2 deletions(-) (limited to 'kernel/bpf') diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 0bba3392b17a..9f9989e0d062 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1616,6 +1616,7 @@ union bpf_attr { * truncated), or smaller (if log buffer wasn't filled completely). */ __u32 btf_log_true_size; + __u32 btf_token_fd; }; struct { diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 22e14124cd61..d87c5c27cde3 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -4777,15 +4777,31 @@ static int bpf_obj_get_info_by_fd(const union bpf_attr *attr, return err; } -#define BPF_BTF_LOAD_LAST_FIELD btf_log_true_size +#define BPF_BTF_LOAD_LAST_FIELD btf_token_fd static int bpf_btf_load(const union bpf_attr *attr, bpfptr_t uattr, __u32 uattr_size) { + struct bpf_token *token = NULL; + if (CHECK_ATTR(BPF_BTF_LOAD)) return -EINVAL; - if (!bpf_capable()) + if (attr->btf_token_fd) { + token = bpf_token_get_from_fd(attr->btf_token_fd); + if (IS_ERR(token)) + return PTR_ERR(token); + if (!bpf_token_allow_cmd(token, BPF_BTF_LOAD)) { + bpf_token_put(token); + token = NULL; + } + } + + if (!bpf_token_capable(token, CAP_BPF)) { + bpf_token_put(token); return -EPERM; + } + + bpf_token_put(token); return btf_new_fd(attr, uattr, uattr_size); } diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 0bba3392b17a..9f9989e0d062 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -1616,6 +1616,7 @@ union bpf_attr { * truncated), or smaller (if log buffer wasn't filled completely). */ __u32 btf_log_true_size; + __u32 btf_token_fd; }; struct { -- cgit v1.2.3 From e1cef620f598853a90f17701fcb1057a6768f7b8 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 30 Nov 2023 10:52:18 -0800 Subject: bpf: add BPF token support to BPF_PROG_LOAD command Add basic support of BPF token to BPF_PROG_LOAD. Wire through a set of allowed BPF program types and attach types, derived from BPF FS at BPF token creation time. Then make sure we perform bpf_token_capable() checks everywhere where it's relevant. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231130185229.2688956-7-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 6 ++ include/uapi/linux/bpf.h | 2 + kernel/bpf/core.c | 1 + kernel/bpf/inode.c | 6 +- kernel/bpf/syscall.c | 87 ++++++++++++++++------ kernel/bpf/token.c | 27 +++++++ tools/include/uapi/linux/bpf.h | 2 + .../selftests/bpf/prog_tests/libbpf_probes.c | 2 + .../testing/selftests/bpf/prog_tests/libbpf_str.c | 3 + 9 files changed, 110 insertions(+), 26 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index e08e8436df38..20af87b59d70 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1461,6 +1461,7 @@ struct bpf_prog_aux { #ifdef CONFIG_SECURITY void *security; #endif + struct bpf_token *token; struct bpf_prog_offload *offload; struct btf *btf; struct bpf_func_info *func_info; @@ -1601,6 +1602,8 @@ struct bpf_token { struct user_namespace *userns; u64 allowed_cmds; u64 allowed_maps; + u64 allowed_progs; + u64 allowed_attachs; }; struct bpf_struct_ops_value; @@ -2238,6 +2241,9 @@ struct bpf_token *bpf_token_get_from_fd(u32 ufd); bool bpf_token_allow_cmd(const struct bpf_token *token, enum bpf_cmd cmd); bool bpf_token_allow_map_type(const struct bpf_token *token, enum bpf_map_type type); +bool bpf_token_allow_prog_type(const struct bpf_token *token, + enum bpf_prog_type prog_type, + enum bpf_attach_type attach_type); int bpf_obj_pin_user(u32 ufd, int path_fd, const char __user *pathname); int bpf_obj_get_user(int path_fd, const char __user *pathname, int flags); diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 9f9989e0d062..4df2d025c784 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1028,6 +1028,7 @@ enum bpf_prog_type { BPF_PROG_TYPE_SK_LOOKUP, BPF_PROG_TYPE_SYSCALL, /* a program that can execute syscalls */ BPF_PROG_TYPE_NETFILTER, + __MAX_BPF_PROG_TYPE }; enum bpf_attach_type { @@ -1504,6 +1505,7 @@ union bpf_attr { * truncated), or smaller (if log buffer wasn't filled completely). */ __u32 log_true_size; + __u32 prog_token_fd; }; struct { /* anonymous struct used by BPF_OBJ_* commands */ diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 4b813da8d6c0..47085839af8d 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -2751,6 +2751,7 @@ void bpf_prog_free(struct bpf_prog *fp) if (aux->dst_prog) bpf_prog_put(aux->dst_prog); + bpf_token_put(aux->token); INIT_WORK(&aux->work, bpf_prog_free_deferred); schedule_work(&aux->work); } diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c index 9c7865d1c53d..5359a0929c35 100644 --- a/kernel/bpf/inode.c +++ b/kernel/bpf/inode.c @@ -619,12 +619,14 @@ static int bpf_show_options(struct seq_file *m, struct dentry *root) else if (opts->delegate_maps) seq_printf(m, ",delegate_maps=0x%llx", opts->delegate_maps); - if (opts->delegate_progs == ~0ULL) + mask = (1ULL << __MAX_BPF_PROG_TYPE) - 1; + if ((opts->delegate_progs & mask) == mask) seq_printf(m, ",delegate_progs=any"); else if (opts->delegate_progs) seq_printf(m, ",delegate_progs=0x%llx", opts->delegate_progs); - if (opts->delegate_attachs == ~0ULL) + mask = (1ULL << __MAX_BPF_ATTACH_TYPE) - 1; + if ((opts->delegate_attachs & mask) == mask) seq_printf(m, ",delegate_attachs=any"); else if (opts->delegate_attachs) seq_printf(m, ",delegate_attachs=0x%llx", opts->delegate_attachs); diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index d87c5c27cde3..2c8393c21b8c 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2608,13 +2608,15 @@ static bool is_perfmon_prog_type(enum bpf_prog_type prog_type) } /* last field in 'union bpf_attr' used by this command */ -#define BPF_PROG_LOAD_LAST_FIELD log_true_size +#define BPF_PROG_LOAD_LAST_FIELD prog_token_fd static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) { enum bpf_prog_type type = attr->prog_type; struct bpf_prog *prog, *dst_prog = NULL; struct btf *attach_btf = NULL; + struct bpf_token *token = NULL; + bool bpf_cap; int err; char license[128]; @@ -2631,10 +2633,31 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) BPF_F_TEST_REG_INVARIANTS)) return -EINVAL; + bpf_prog_load_fixup_attach_type(attr); + + if (attr->prog_token_fd) { + token = bpf_token_get_from_fd(attr->prog_token_fd); + if (IS_ERR(token)) + return PTR_ERR(token); + /* if current token doesn't grant prog loading permissions, + * then we can't use this token, so ignore it and rely on + * system-wide capabilities checks + */ + if (!bpf_token_allow_cmd(token, BPF_PROG_LOAD) || + !bpf_token_allow_prog_type(token, attr->prog_type, + attr->expected_attach_type)) { + bpf_token_put(token); + token = NULL; + } + } + + bpf_cap = bpf_token_capable(token, CAP_BPF); + err = -EPERM; + if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && (attr->prog_flags & BPF_F_ANY_ALIGNMENT) && - !bpf_capable()) - return -EPERM; + !bpf_cap) + goto put_token; /* Intent here is for unprivileged_bpf_disabled to block BPF program * creation for unprivileged users; other actions depend @@ -2643,21 +2666,23 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) * capability checks are still carried out for these * and other operations. */ - if (sysctl_unprivileged_bpf_disabled && !bpf_capable()) - return -EPERM; + if (sysctl_unprivileged_bpf_disabled && !bpf_cap) + goto put_token; if (attr->insn_cnt == 0 || - attr->insn_cnt > (bpf_capable() ? BPF_COMPLEXITY_LIMIT_INSNS : BPF_MAXINSNS)) - return -E2BIG; + attr->insn_cnt > (bpf_cap ? BPF_COMPLEXITY_LIMIT_INSNS : BPF_MAXINSNS)) { + err = -E2BIG; + goto put_token; + } if (type != BPF_PROG_TYPE_SOCKET_FILTER && type != BPF_PROG_TYPE_CGROUP_SKB && - !bpf_capable()) - return -EPERM; + !bpf_cap) + goto put_token; - if (is_net_admin_prog_type(type) && !bpf_net_capable()) - return -EPERM; - if (is_perfmon_prog_type(type) && !perfmon_capable()) - return -EPERM; + if (is_net_admin_prog_type(type) && !bpf_token_capable(token, CAP_NET_ADMIN)) + goto put_token; + if (is_perfmon_prog_type(type) && !bpf_token_capable(token, CAP_PERFMON)) + goto put_token; /* attach_prog_fd/attach_btf_obj_fd can specify fd of either bpf_prog * or btf, we need to check which one it is @@ -2667,27 +2692,33 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) if (IS_ERR(dst_prog)) { dst_prog = NULL; attach_btf = btf_get_by_fd(attr->attach_btf_obj_fd); - if (IS_ERR(attach_btf)) - return -EINVAL; + if (IS_ERR(attach_btf)) { + err = -EINVAL; + goto put_token; + } if (!btf_is_kernel(attach_btf)) { /* attaching through specifying bpf_prog's BTF * objects directly might be supported eventually */ btf_put(attach_btf); - return -ENOTSUPP; + err = -ENOTSUPP; + goto put_token; } } } else if (attr->attach_btf_id) { /* fall back to vmlinux BTF, if BTF type ID is specified */ attach_btf = bpf_get_btf_vmlinux(); - if (IS_ERR(attach_btf)) - return PTR_ERR(attach_btf); - if (!attach_btf) - return -EINVAL; + if (IS_ERR(attach_btf)) { + err = PTR_ERR(attach_btf); + goto put_token; + } + if (!attach_btf) { + err = -EINVAL; + goto put_token; + } btf_get(attach_btf); } - bpf_prog_load_fixup_attach_type(attr); if (bpf_prog_load_check_attach(type, attr->expected_attach_type, attach_btf, attr->attach_btf_id, dst_prog)) { @@ -2695,7 +2726,8 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) bpf_prog_put(dst_prog); if (attach_btf) btf_put(attach_btf); - return -EINVAL; + err = -EINVAL; + goto put_token; } /* plain bpf_prog allocation */ @@ -2705,7 +2737,8 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) bpf_prog_put(dst_prog); if (attach_btf) btf_put(attach_btf); - return -ENOMEM; + err = -EINVAL; + goto put_token; } prog->expected_attach_type = attr->expected_attach_type; @@ -2716,6 +2749,10 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) prog->aux->sleepable = attr->prog_flags & BPF_F_SLEEPABLE; prog->aux->xdp_has_frags = attr->prog_flags & BPF_F_XDP_HAS_FRAGS; + /* move token into prog->aux, reuse taken refcnt */ + prog->aux->token = token; + token = NULL; + err = security_bpf_prog_alloc(prog->aux); if (err) goto free_prog; @@ -2817,6 +2854,8 @@ free_prog: if (prog->aux->attach_btf) btf_put(prog->aux->attach_btf); bpf_prog_free(prog); +put_token: + bpf_token_put(token); return err; } @@ -3806,7 +3845,7 @@ static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog, case BPF_PROG_TYPE_SK_LOOKUP: return attach_type == prog->expected_attach_type ? 0 : -EINVAL; case BPF_PROG_TYPE_CGROUP_SKB: - if (!bpf_net_capable()) + if (!bpf_token_capable(prog->aux->token, CAP_NET_ADMIN)) /* cg-skb progs can be loaded by unpriv user. * check permissions at attach time. */ diff --git a/kernel/bpf/token.c b/kernel/bpf/token.c index 06c34dae658e..5a51e6b8f6bf 100644 --- a/kernel/bpf/token.c +++ b/kernel/bpf/token.c @@ -79,6 +79,20 @@ static void bpf_token_show_fdinfo(struct seq_file *m, struct file *filp) seq_printf(m, "allowed_maps:\tany\n"); else seq_printf(m, "allowed_maps:\t0x%llx\n", token->allowed_maps); + + BUILD_BUG_ON(__MAX_BPF_PROG_TYPE >= 64); + mask = (1ULL << __MAX_BPF_PROG_TYPE) - 1; + if ((token->allowed_progs & mask) == mask) + seq_printf(m, "allowed_progs:\tany\n"); + else + seq_printf(m, "allowed_progs:\t0x%llx\n", token->allowed_progs); + + BUILD_BUG_ON(__MAX_BPF_ATTACH_TYPE >= 64); + mask = (1ULL << __MAX_BPF_ATTACH_TYPE) - 1; + if ((token->allowed_attachs & mask) == mask) + seq_printf(m, "allowed_attachs:\tany\n"); + else + seq_printf(m, "allowed_attachs:\t0x%llx\n", token->allowed_attachs); } #define BPF_TOKEN_INODE_NAME "bpf-token" @@ -169,6 +183,8 @@ int bpf_token_create(union bpf_attr *attr) mnt_opts = path.dentry->d_sb->s_fs_info; token->allowed_cmds = mnt_opts->delegate_cmds; token->allowed_maps = mnt_opts->delegate_maps; + token->allowed_progs = mnt_opts->delegate_progs; + token->allowed_attachs = mnt_opts->delegate_attachs; fd = get_unused_fd_flags(O_CLOEXEC); if (fd < 0) { @@ -228,3 +244,14 @@ bool bpf_token_allow_map_type(const struct bpf_token *token, enum bpf_map_type t return token->allowed_maps & (1ULL << type); } + +bool bpf_token_allow_prog_type(const struct bpf_token *token, + enum bpf_prog_type prog_type, + enum bpf_attach_type attach_type) +{ + if (!token || prog_type >= __MAX_BPF_PROG_TYPE || attach_type >= __MAX_BPF_ATTACH_TYPE) + return false; + + return (token->allowed_progs & (1ULL << prog_type)) && + (token->allowed_attachs & (1ULL << attach_type)); +} diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 9f9989e0d062..4df2d025c784 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -1028,6 +1028,7 @@ enum bpf_prog_type { BPF_PROG_TYPE_SK_LOOKUP, BPF_PROG_TYPE_SYSCALL, /* a program that can execute syscalls */ BPF_PROG_TYPE_NETFILTER, + __MAX_BPF_PROG_TYPE }; enum bpf_attach_type { @@ -1504,6 +1505,7 @@ union bpf_attr { * truncated), or smaller (if log buffer wasn't filled completely). */ __u32 log_true_size; + __u32 prog_token_fd; }; struct { /* anonymous struct used by BPF_OBJ_* commands */ diff --git a/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c b/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c index 573249a2814d..4ed46ed58a7b 100644 --- a/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c +++ b/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c @@ -30,6 +30,8 @@ void test_libbpf_probe_prog_types(void) if (prog_type == BPF_PROG_TYPE_UNSPEC) continue; + if (strcmp(prog_type_name, "__MAX_BPF_PROG_TYPE") == 0) + continue; if (!test__start_subtest(prog_type_name)) continue; diff --git a/tools/testing/selftests/bpf/prog_tests/libbpf_str.c b/tools/testing/selftests/bpf/prog_tests/libbpf_str.c index 2a0633f43c73..384bc1f7a65e 100644 --- a/tools/testing/selftests/bpf/prog_tests/libbpf_str.c +++ b/tools/testing/selftests/bpf/prog_tests/libbpf_str.c @@ -189,6 +189,9 @@ static void test_libbpf_bpf_prog_type_str(void) const char *prog_type_str; char buf[256]; + if (prog_type == __MAX_BPF_PROG_TYPE) + continue; + prog_type_name = btf__str_by_offset(btf, e->name_off); prog_type_str = libbpf_bpf_prog_type_str(prog_type); ASSERT_OK_PTR(prog_type_str, prog_type_name); -- cgit v1.2.3 From 4cbb270e115bc197ff2046aeb54cc951666b16ec Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 30 Nov 2023 10:52:19 -0800 Subject: bpf: take into account BPF token when fetching helper protos Instead of performing unconditional system-wide bpf_capable() and perfmon_capable() calls inside bpf_base_func_proto() function (and other similar ones) to determine eligibility of a given BPF helper for a given program, use previously recorded BPF token during BPF_PROG_LOAD command handling to inform the decision. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231130185229.2688956-8-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- drivers/media/rc/bpf-lirc.c | 2 +- include/linux/bpf.h | 5 +++-- kernel/bpf/cgroup.c | 6 +++--- kernel/bpf/helpers.c | 6 +++--- kernel/bpf/syscall.c | 5 +++-- kernel/trace/bpf_trace.c | 2 +- net/core/filter.c | 32 ++++++++++++++++---------------- net/ipv4/bpf_tcp_ca.c | 2 +- net/netfilter/nf_bpf_link.c | 2 +- 9 files changed, 32 insertions(+), 30 deletions(-) (limited to 'kernel/bpf') diff --git a/drivers/media/rc/bpf-lirc.c b/drivers/media/rc/bpf-lirc.c index fe17c7f98e81..6d07693c6b9f 100644 --- a/drivers/media/rc/bpf-lirc.c +++ b/drivers/media/rc/bpf-lirc.c @@ -110,7 +110,7 @@ lirc_mode2_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_get_prandom_u32: return &bpf_get_prandom_u32_proto; case BPF_FUNC_trace_printk: - if (perfmon_capable()) + if (bpf_token_capable(prog->aux->token, CAP_PERFMON)) return bpf_get_trace_printk_proto(); fallthrough; default: diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 20af87b59d70..2a3ab4f3dd8c 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2492,7 +2492,8 @@ const char *btf_find_decl_tag_value(const struct btf *btf, const struct btf_type struct bpf_prog *bpf_prog_by_id(u32 id); struct bpf_link *bpf_link_by_id(u32 id); -const struct bpf_func_proto *bpf_base_func_proto(enum bpf_func_id func_id); +const struct bpf_func_proto *bpf_base_func_proto(enum bpf_func_id func_id, + const struct bpf_prog *prog); void bpf_task_storage_free(struct task_struct *task); void bpf_cgrp_storage_free(struct cgroup *cgroup); bool bpf_prog_has_kfunc_call(const struct bpf_prog *prog); @@ -2752,7 +2753,7 @@ static inline int btf_struct_access(struct bpf_verifier_log *log, } static inline const struct bpf_func_proto * -bpf_base_func_proto(enum bpf_func_id func_id) +bpf_base_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { return NULL; } diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c index 491d20038cbe..98e0e3835b28 100644 --- a/kernel/bpf/cgroup.c +++ b/kernel/bpf/cgroup.c @@ -1630,7 +1630,7 @@ cgroup_dev_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_perf_event_output: return &bpf_event_output_data_proto; default: - return bpf_base_func_proto(func_id); + return bpf_base_func_proto(func_id, prog); } } @@ -2191,7 +2191,7 @@ sysctl_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_perf_event_output: return &bpf_event_output_data_proto; default: - return bpf_base_func_proto(func_id); + return bpf_base_func_proto(func_id, prog); } } @@ -2348,7 +2348,7 @@ cg_sockopt_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_perf_event_output: return &bpf_event_output_data_proto; default: - return bpf_base_func_proto(func_id); + return bpf_base_func_proto(func_id, prog); } } diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index ee9bdf29246a..b3be5742d6f1 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -1679,7 +1679,7 @@ const struct bpf_func_proto bpf_probe_read_kernel_str_proto __weak; const struct bpf_func_proto bpf_task_pt_regs_proto __weak; const struct bpf_func_proto * -bpf_base_func_proto(enum bpf_func_id func_id) +bpf_base_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { switch (func_id) { case BPF_FUNC_map_lookup_elem: @@ -1730,7 +1730,7 @@ bpf_base_func_proto(enum bpf_func_id func_id) break; } - if (!bpf_capable()) + if (!bpf_token_capable(prog->aux->token, CAP_BPF)) return NULL; switch (func_id) { @@ -1788,7 +1788,7 @@ bpf_base_func_proto(enum bpf_func_id func_id) break; } - if (!perfmon_capable()) + if (!bpf_token_capable(prog->aux->token, CAP_PERFMON)) return NULL; switch (func_id) { diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 2c8393c21b8c..1cc03f08c9cd 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -5712,7 +5712,7 @@ static const struct bpf_func_proto bpf_sys_bpf_proto = { const struct bpf_func_proto * __weak tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { - return bpf_base_func_proto(func_id); + return bpf_base_func_proto(func_id, prog); } BPF_CALL_1(bpf_sys_close, u32, fd) @@ -5762,7 +5762,8 @@ syscall_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { switch (func_id) { case BPF_FUNC_sys_bpf: - return !perfmon_capable() ? NULL : &bpf_sys_bpf_proto; + return !bpf_token_capable(prog->aux->token, CAP_PERFMON) + ? NULL : &bpf_sys_bpf_proto; case BPF_FUNC_btf_find_by_name_kind: return &bpf_btf_find_by_name_kind_proto; case BPF_FUNC_sys_close: diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 1648bde28f01..774cf476a892 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1626,7 +1626,7 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_trace_vprintk: return bpf_get_trace_vprintk_proto(); default: - return bpf_base_func_proto(func_id); + return bpf_base_func_proto(func_id, prog); } } diff --git a/net/core/filter.c b/net/core/filter.c index 0adaa4afa35f..0bf2a03d8203 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -87,7 +87,7 @@ #include "dev.h" static const struct bpf_func_proto * -bpf_sk_base_func_proto(enum bpf_func_id func_id); +bpf_sk_base_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog); int copy_bpf_fprog_from_user(struct sock_fprog *dst, sockptr_t src, int len) { @@ -7841,7 +7841,7 @@ sock_filter_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_ktime_get_coarse_ns: return &bpf_ktime_get_coarse_ns_proto; default: - return bpf_base_func_proto(func_id); + return bpf_base_func_proto(func_id, prog); } } @@ -7934,7 +7934,7 @@ sock_addr_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return NULL; } default: - return bpf_sk_base_func_proto(func_id); + return bpf_sk_base_func_proto(func_id, prog); } } @@ -7953,7 +7953,7 @@ sk_filter_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_perf_event_output: return &bpf_skb_event_output_proto; default: - return bpf_sk_base_func_proto(func_id); + return bpf_sk_base_func_proto(func_id, prog); } } @@ -8140,7 +8140,7 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) #endif #endif default: - return bpf_sk_base_func_proto(func_id); + return bpf_sk_base_func_proto(func_id, prog); } } @@ -8199,7 +8199,7 @@ xdp_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) #endif #endif default: - return bpf_sk_base_func_proto(func_id); + return bpf_sk_base_func_proto(func_id, prog); } #if IS_MODULE(CONFIG_NF_CONNTRACK) && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES) @@ -8260,7 +8260,7 @@ sock_ops_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_tcp_sock_proto; #endif /* CONFIG_INET */ default: - return bpf_sk_base_func_proto(func_id); + return bpf_sk_base_func_proto(func_id, prog); } } @@ -8302,7 +8302,7 @@ sk_msg_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_get_cgroup_classid_curr_proto; #endif default: - return bpf_sk_base_func_proto(func_id); + return bpf_sk_base_func_proto(func_id, prog); } } @@ -8346,7 +8346,7 @@ sk_skb_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_skc_lookup_tcp_proto; #endif default: - return bpf_sk_base_func_proto(func_id); + return bpf_sk_base_func_proto(func_id, prog); } } @@ -8357,7 +8357,7 @@ flow_dissector_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_skb_load_bytes: return &bpf_flow_dissector_load_bytes_proto; default: - return bpf_sk_base_func_proto(func_id); + return bpf_sk_base_func_proto(func_id, prog); } } @@ -8384,7 +8384,7 @@ lwt_out_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_skb_under_cgroup: return &bpf_skb_under_cgroup_proto; default: - return bpf_sk_base_func_proto(func_id); + return bpf_sk_base_func_proto(func_id, prog); } } @@ -11215,7 +11215,7 @@ sk_reuseport_func_proto(enum bpf_func_id func_id, case BPF_FUNC_ktime_get_coarse_ns: return &bpf_ktime_get_coarse_ns_proto; default: - return bpf_base_func_proto(func_id); + return bpf_base_func_proto(func_id, prog); } } @@ -11397,7 +11397,7 @@ sk_lookup_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_sk_release: return &bpf_sk_release_proto; default: - return bpf_sk_base_func_proto(func_id); + return bpf_sk_base_func_proto(func_id, prog); } } @@ -11731,7 +11731,7 @@ const struct bpf_func_proto bpf_sock_from_file_proto = { }; static const struct bpf_func_proto * -bpf_sk_base_func_proto(enum bpf_func_id func_id) +bpf_sk_base_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { const struct bpf_func_proto *func; @@ -11760,10 +11760,10 @@ bpf_sk_base_func_proto(enum bpf_func_id func_id) case BPF_FUNC_ktime_get_coarse_ns: return &bpf_ktime_get_coarse_ns_proto; default: - return bpf_base_func_proto(func_id); + return bpf_base_func_proto(func_id, prog); } - if (!perfmon_capable()) + if (!bpf_token_capable(prog->aux->token, CAP_PERFMON)) return NULL; return func; diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c index 39dcccf0f174..c7bbd8f3c708 100644 --- a/net/ipv4/bpf_tcp_ca.c +++ b/net/ipv4/bpf_tcp_ca.c @@ -191,7 +191,7 @@ bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id, case BPF_FUNC_ktime_get_coarse_ns: return &bpf_ktime_get_coarse_ns_proto; default: - return bpf_base_func_proto(func_id); + return bpf_base_func_proto(func_id, prog); } } diff --git a/net/netfilter/nf_bpf_link.c b/net/netfilter/nf_bpf_link.c index e502ec00b2fe..1969facac91c 100644 --- a/net/netfilter/nf_bpf_link.c +++ b/net/netfilter/nf_bpf_link.c @@ -314,7 +314,7 @@ static bool nf_is_valid_access(int off, int size, enum bpf_access_type type, static const struct bpf_func_proto * bpf_nf_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { - return bpf_base_func_proto(func_id); + return bpf_base_func_proto(func_id, prog); } const struct bpf_verifier_ops netfilter_verifier_ops = { -- cgit v1.2.3 From 8062fb12de99b2da33754c6a3be1bfc30d9a35f4 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 30 Nov 2023 10:52:20 -0800 Subject: bpf: consistently use BPF token throughout BPF verifier logic Remove remaining direct queries to perfmon_capable() and bpf_capable() in BPF verifier logic and instead use BPF token (if available) to make decisions about privileges. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231130185229.2688956-9-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 16 ++++++++-------- include/linux/filter.h | 2 +- kernel/bpf/arraymap.c | 2 +- kernel/bpf/core.c | 2 +- kernel/bpf/verifier.c | 13 ++++++------- net/core/filter.c | 4 ++-- 6 files changed, 19 insertions(+), 20 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 2a3ab4f3dd8c..435abad3cc61 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2200,24 +2200,24 @@ extern int sysctl_unprivileged_bpf_disabled; bool bpf_token_capable(const struct bpf_token *token, int cap); -static inline bool bpf_allow_ptr_leaks(void) +static inline bool bpf_allow_ptr_leaks(const struct bpf_token *token) { - return perfmon_capable(); + return bpf_token_capable(token, CAP_PERFMON); } -static inline bool bpf_allow_uninit_stack(void) +static inline bool bpf_allow_uninit_stack(const struct bpf_token *token) { - return perfmon_capable(); + return bpf_token_capable(token, CAP_PERFMON); } -static inline bool bpf_bypass_spec_v1(void) +static inline bool bpf_bypass_spec_v1(const struct bpf_token *token) { - return cpu_mitigations_off() || perfmon_capable(); + return cpu_mitigations_off() || bpf_token_capable(token, CAP_PERFMON); } -static inline bool bpf_bypass_spec_v4(void) +static inline bool bpf_bypass_spec_v4(const struct bpf_token *token) { - return cpu_mitigations_off() || perfmon_capable(); + return cpu_mitigations_off() || bpf_token_capable(token, CAP_PERFMON); } int bpf_map_new_fd(struct bpf_map *map, int flags); diff --git a/include/linux/filter.h b/include/linux/filter.h index a4953fafc8cb..14354605ad26 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -1139,7 +1139,7 @@ static inline bool bpf_jit_blinding_enabled(struct bpf_prog *prog) return false; if (!bpf_jit_harden) return false; - if (bpf_jit_harden == 1 && bpf_capable()) + if (bpf_jit_harden == 1 && bpf_token_capable(prog->aux->token, CAP_BPF)) return false; return true; diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 4a4a67956e21..8d365bda9a8b 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -82,7 +82,7 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr) bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY; int numa_node = bpf_map_attr_numa_node(attr); u32 elem_size, index_mask, max_entries; - bool bypass_spec_v1 = bpf_bypass_spec_v1(); + bool bypass_spec_v1 = bpf_bypass_spec_v1(NULL); u64 array_size, mask64; struct bpf_array *array; diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 47085839af8d..ced511f44174 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -675,7 +675,7 @@ static bool bpf_prog_kallsyms_candidate(const struct bpf_prog *fp) void bpf_prog_kallsyms_add(struct bpf_prog *fp) { if (!bpf_prog_kallsyms_candidate(fp) || - !bpf_capable()) + !bpf_token_capable(fp->aux->token, CAP_BPF)) return; bpf_prog_ksym_set_addr(fp); diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index e5ce530641ba..45e85fb76d82 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -20597,7 +20597,12 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u3 env->prog = *prog; env->ops = bpf_verifier_ops[env->prog->type]; env->fd_array = make_bpfptr(attr->fd_array, uattr.is_kernel); - is_priv = bpf_capable(); + + env->allow_ptr_leaks = bpf_allow_ptr_leaks(env->prog->aux->token); + env->allow_uninit_stack = bpf_allow_uninit_stack(env->prog->aux->token); + env->bypass_spec_v1 = bpf_bypass_spec_v1(env->prog->aux->token); + env->bypass_spec_v4 = bpf_bypass_spec_v4(env->prog->aux->token); + env->bpf_capable = is_priv = bpf_token_capable(env->prog->aux->token, CAP_BPF); bpf_get_btf_vmlinux(); @@ -20629,12 +20634,6 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u3 if (attr->prog_flags & BPF_F_ANY_ALIGNMENT) env->strict_alignment = false; - env->allow_ptr_leaks = bpf_allow_ptr_leaks(); - env->allow_uninit_stack = bpf_allow_uninit_stack(); - env->bypass_spec_v1 = bpf_bypass_spec_v1(); - env->bypass_spec_v4 = bpf_bypass_spec_v4(); - env->bpf_capable = bpf_capable(); - if (is_priv) env->test_state_freq = attr->prog_flags & BPF_F_TEST_STATE_FREQ; env->test_reg_invariants = attr->prog_flags & BPF_F_TEST_REG_INVARIANTS; diff --git a/net/core/filter.c b/net/core/filter.c index 0bf2a03d8203..adcfc2c25754 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -8559,7 +8559,7 @@ static bool cg_skb_is_valid_access(int off, int size, return false; case bpf_ctx_range(struct __sk_buff, data): case bpf_ctx_range(struct __sk_buff, data_end): - if (!bpf_capable()) + if (!bpf_token_capable(prog->aux->token, CAP_BPF)) return false; break; } @@ -8571,7 +8571,7 @@ static bool cg_skb_is_valid_access(int off, int size, case bpf_ctx_range_till(struct __sk_buff, cb[0], cb[4]): break; case bpf_ctx_range(struct __sk_buff, tstamp): - if (!bpf_capable()) + if (!bpf_token_capable(prog->aux->token, CAP_BPF)) return false; break; default: -- cgit v1.2.3 From c3dd6e94df7193f33f45d33303f5e85afb2a72dc Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 30 Nov 2023 10:52:21 -0800 Subject: bpf,lsm: refactor bpf_prog_alloc/bpf_prog_free LSM hooks Based on upstream discussion ([0]), rework existing bpf_prog_alloc_security LSM hook. Rename it to bpf_prog_load and instead of passing bpf_prog_aux, pass proper bpf_prog pointer for a full BPF program struct. Also, we pass bpf_attr union with all the user-provided arguments for BPF_PROG_LOAD command. This will give LSMs as much information as we can basically provide. The hook is also BPF token-aware now, and optional bpf_token struct is passed as a third argument. bpf_prog_load LSM hook is called after a bunch of sanity checks were performed, bpf_prog and bpf_prog_aux were allocated and filled out, but right before performing full-fledged BPF verification step. bpf_prog_free LSM hook is now accepting struct bpf_prog argument, for consistency. SELinux code is adjusted to all new names, types, and signatures. Note, given that bpf_prog_load (previously bpf_prog_alloc) hook can be used by some LSMs to allocate extra security blob, but also by other LSMs to reject BPF program loading, we need to make sure that bpf_prog_free LSM hook is called after bpf_prog_load/bpf_prog_alloc one *even* if the hook itself returned error. If we don't do that, we run the risk of leaking memory. This seems to be possible today when combining SELinux and BPF LSM, as one example, depending on their relative ordering. Also, for BPF LSM setup, add bpf_prog_load and bpf_prog_free to sleepable LSM hooks list, as they are both executed in sleepable context. Also drop bpf_prog_load hook from untrusted, as there is no issue with refcount or anything else anymore, that originally forced us to add it to untrusted list in c0c852dd1876 ("bpf: Do not mark certain LSM hook arguments as trusted"). We now trigger this hook much later and it should not be an issue anymore. [0] https://lore.kernel.org/bpf/9fe88aef7deabbe87d3fc38c4aea3c69.paul@paul-moore.com/ Acked-by: Paul Moore Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231130185229.2688956-10-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/lsm_hook_defs.h | 5 +++-- include/linux/security.h | 12 +++++++----- kernel/bpf/bpf_lsm.c | 5 +++-- kernel/bpf/syscall.c | 25 +++++++++++++------------ security/security.c | 25 +++++++++++++++---------- security/selinux/hooks.c | 15 ++++++++------- 6 files changed, 49 insertions(+), 38 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index ff217a5ce552..41ec4a7c070e 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -400,8 +400,9 @@ LSM_HOOK(int, 0, bpf_map, struct bpf_map *map, fmode_t fmode) LSM_HOOK(int, 0, bpf_prog, struct bpf_prog *prog) LSM_HOOK(int, 0, bpf_map_alloc_security, struct bpf_map *map) LSM_HOOK(void, LSM_RET_VOID, bpf_map_free_security, struct bpf_map *map) -LSM_HOOK(int, 0, bpf_prog_alloc_security, struct bpf_prog_aux *aux) -LSM_HOOK(void, LSM_RET_VOID, bpf_prog_free_security, struct bpf_prog_aux *aux) +LSM_HOOK(int, 0, bpf_prog_load, struct bpf_prog *prog, union bpf_attr *attr, + struct bpf_token *token) +LSM_HOOK(void, LSM_RET_VOID, bpf_prog_free, struct bpf_prog *prog) #endif /* CONFIG_BPF_SYSCALL */ LSM_HOOK(int, 0, locked_down, enum lockdown_reason what) diff --git a/include/linux/security.h b/include/linux/security.h index 1d1df326c881..65467eef6678 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -2020,15 +2020,16 @@ static inline void securityfs_remove(struct dentry *dentry) union bpf_attr; struct bpf_map; struct bpf_prog; -struct bpf_prog_aux; +struct bpf_token; #ifdef CONFIG_SECURITY extern int security_bpf(int cmd, union bpf_attr *attr, unsigned int size); extern int security_bpf_map(struct bpf_map *map, fmode_t fmode); extern int security_bpf_prog(struct bpf_prog *prog); extern int security_bpf_map_alloc(struct bpf_map *map); extern void security_bpf_map_free(struct bpf_map *map); -extern int security_bpf_prog_alloc(struct bpf_prog_aux *aux); -extern void security_bpf_prog_free(struct bpf_prog_aux *aux); +extern int security_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, + struct bpf_token *token); +extern void security_bpf_prog_free(struct bpf_prog *prog); #else static inline int security_bpf(int cmd, union bpf_attr *attr, unsigned int size) @@ -2054,12 +2055,13 @@ static inline int security_bpf_map_alloc(struct bpf_map *map) static inline void security_bpf_map_free(struct bpf_map *map) { } -static inline int security_bpf_prog_alloc(struct bpf_prog_aux *aux) +static inline int security_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, + struct bpf_token *token) { return 0; } -static inline void security_bpf_prog_free(struct bpf_prog_aux *aux) +static inline void security_bpf_prog_free(struct bpf_prog *prog) { } #endif /* CONFIG_SECURITY */ #endif /* CONFIG_BPF_SYSCALL */ diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index e14c822f8911..3e956f6302f3 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -263,6 +263,8 @@ BTF_ID(func, bpf_lsm_bpf_map) BTF_ID(func, bpf_lsm_bpf_map_alloc_security) BTF_ID(func, bpf_lsm_bpf_map_free_security) BTF_ID(func, bpf_lsm_bpf_prog) +BTF_ID(func, bpf_lsm_bpf_prog_load) +BTF_ID(func, bpf_lsm_bpf_prog_free) BTF_ID(func, bpf_lsm_bprm_check_security) BTF_ID(func, bpf_lsm_bprm_committed_creds) BTF_ID(func, bpf_lsm_bprm_committing_creds) @@ -346,8 +348,7 @@ BTF_SET_END(sleepable_lsm_hooks) BTF_SET_START(untrusted_lsm_hooks) BTF_ID(func, bpf_lsm_bpf_map_free_security) -BTF_ID(func, bpf_lsm_bpf_prog_alloc_security) -BTF_ID(func, bpf_lsm_bpf_prog_free_security) +BTF_ID(func, bpf_lsm_bpf_prog_free) BTF_ID(func, bpf_lsm_file_alloc_security) BTF_ID(func, bpf_lsm_file_free_security) #ifdef CONFIG_SECURITY_NETWORK diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 1cc03f08c9cd..7717c7c7b95d 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2162,7 +2162,7 @@ static void __bpf_prog_put_rcu(struct rcu_head *rcu) kvfree(aux->func_info); kfree(aux->func_info_aux); free_uid(aux->user); - security_bpf_prog_free(aux); + security_bpf_prog_free(aux->prog); bpf_prog_free(aux->prog); } @@ -2753,10 +2753,6 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) prog->aux->token = token; token = NULL; - err = security_bpf_prog_alloc(prog->aux); - if (err) - goto free_prog; - prog->aux->user = get_current_user(); prog->len = attr->insn_cnt; @@ -2764,12 +2760,12 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) if (copy_from_bpfptr(prog->insns, make_bpfptr(attr->insns, uattr.is_kernel), bpf_prog_insn_size(prog)) != 0) - goto free_prog_sec; + goto free_prog; /* copy eBPF program license from user space */ if (strncpy_from_bpfptr(license, make_bpfptr(attr->license, uattr.is_kernel), sizeof(license) - 1) < 0) - goto free_prog_sec; + goto free_prog; license[sizeof(license) - 1] = 0; /* eBPF programs must be GPL compatible to use GPL-ed functions */ @@ -2783,25 +2779,29 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) if (bpf_prog_is_dev_bound(prog->aux)) { err = bpf_prog_dev_bound_init(prog, attr); if (err) - goto free_prog_sec; + goto free_prog; } if (type == BPF_PROG_TYPE_EXT && dst_prog && bpf_prog_is_dev_bound(dst_prog->aux)) { err = bpf_prog_dev_bound_inherit(prog, dst_prog); if (err) - goto free_prog_sec; + goto free_prog; } /* find program type: socket_filter vs tracing_filter */ err = find_prog_type(type, prog); if (err < 0) - goto free_prog_sec; + goto free_prog; prog->aux->load_time = ktime_get_boottime_ns(); err = bpf_obj_name_cpy(prog->aux->name, attr->prog_name, sizeof(attr->prog_name)); if (err < 0) + goto free_prog; + + err = security_bpf_prog_load(prog, attr, token); + if (err) goto free_prog_sec; /* run eBPF verifier */ @@ -2847,10 +2847,11 @@ free_used_maps: */ __bpf_prog_put_noref(prog, prog->aux->real_func_cnt); return err; + free_prog_sec: - free_uid(prog->aux->user); - security_bpf_prog_free(prog->aux); + security_bpf_prog_free(prog); free_prog: + free_uid(prog->aux->user); if (prog->aux->attach_btf) btf_put(prog->aux->attach_btf); bpf_prog_free(prog); diff --git a/security/security.c b/security/security.c index dcb3e7014f9b..c8a1c66cfaad 100644 --- a/security/security.c +++ b/security/security.c @@ -5180,16 +5180,21 @@ int security_bpf_map_alloc(struct bpf_map *map) } /** - * security_bpf_prog_alloc() - Allocate a bpf program LSM blob - * @aux: bpf program aux info struct + * security_bpf_prog_load() - Check if loading of BPF program is allowed + * @prog: BPF program object + * @attr: BPF syscall attributes used to create BPF program + * @token: BPF token used to grant user access to BPF subsystem * - * Initialize the security field inside bpf program. + * Perform an access control check when the kernel loads a BPF program and + * allocates associated BPF program object. This hook is also responsible for + * allocating any required LSM state for the BPF program. * * Return: Returns 0 on success, error on failure. */ -int security_bpf_prog_alloc(struct bpf_prog_aux *aux) +int security_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, + struct bpf_token *token) { - return call_int_hook(bpf_prog_alloc_security, 0, aux); + return call_int_hook(bpf_prog_load, 0, prog, attr, token); } /** @@ -5204,14 +5209,14 @@ void security_bpf_map_free(struct bpf_map *map) } /** - * security_bpf_prog_free() - Free a bpf program's LSM blob - * @aux: bpf program aux info struct + * security_bpf_prog_free() - Free a BPF program's LSM blob + * @prog: BPF program struct * - * Clean up the security information stored inside bpf prog. + * Clean up the security information stored inside BPF program. */ -void security_bpf_prog_free(struct bpf_prog_aux *aux) +void security_bpf_prog_free(struct bpf_prog *prog) { - call_void_hook(bpf_prog_free_security, aux); + call_void_hook(bpf_prog_free, prog); } #endif /* CONFIG_BPF_SYSCALL */ diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index feda711c6b7b..eabee39e983c 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -6805,7 +6805,8 @@ static void selinux_bpf_map_free(struct bpf_map *map) kfree(bpfsec); } -static int selinux_bpf_prog_alloc(struct bpf_prog_aux *aux) +static int selinux_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, + struct bpf_token *token) { struct bpf_security_struct *bpfsec; @@ -6814,16 +6815,16 @@ static int selinux_bpf_prog_alloc(struct bpf_prog_aux *aux) return -ENOMEM; bpfsec->sid = current_sid(); - aux->security = bpfsec; + prog->aux->security = bpfsec; return 0; } -static void selinux_bpf_prog_free(struct bpf_prog_aux *aux) +static void selinux_bpf_prog_free(struct bpf_prog *prog) { - struct bpf_security_struct *bpfsec = aux->security; + struct bpf_security_struct *bpfsec = prog->aux->security; - aux->security = NULL; + prog->aux->security = NULL; kfree(bpfsec); } #endif @@ -7180,7 +7181,7 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = { LSM_HOOK_INIT(bpf_map, selinux_bpf_map), LSM_HOOK_INIT(bpf_prog, selinux_bpf_prog), LSM_HOOK_INIT(bpf_map_free_security, selinux_bpf_map_free), - LSM_HOOK_INIT(bpf_prog_free_security, selinux_bpf_prog_free), + LSM_HOOK_INIT(bpf_prog_free, selinux_bpf_prog_free), #endif #ifdef CONFIG_PERF_EVENTS @@ -7238,7 +7239,7 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = { #endif #ifdef CONFIG_BPF_SYSCALL LSM_HOOK_INIT(bpf_map_alloc_security, selinux_bpf_map_alloc), - LSM_HOOK_INIT(bpf_prog_alloc_security, selinux_bpf_prog_alloc), + LSM_HOOK_INIT(bpf_prog_load, selinux_bpf_prog_load), #endif #ifdef CONFIG_PERF_EVENTS LSM_HOOK_INIT(perf_event_alloc, selinux_perf_event_alloc), -- cgit v1.2.3 From 66d636d70a79c1d37e3eea67ab50969e6aaef983 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 30 Nov 2023 10:52:22 -0800 Subject: bpf,lsm: refactor bpf_map_alloc/bpf_map_free LSM hooks Similarly to bpf_prog_alloc LSM hook, rename and extend bpf_map_alloc hook into bpf_map_create, taking not just struct bpf_map, but also bpf_attr and bpf_token, to give a fuller context to LSMs. Unlike bpf_prog_alloc, there is no need to move the hook around, as it currently is firing right before allocating BPF map ID and FD, which seems to be a sweet spot. But like bpf_prog_alloc/bpf_prog_free combo, make sure that bpf_map_free LSM hook is called even if bpf_map_create hook returned error, as if few LSMs are combined together it could be that one LSM successfully allocated security blob for its needs, while subsequent LSM rejected BPF map creation. The former LSM would still need to free up LSM blob, so we need to ensure security_bpf_map_free() is called regardless of the outcome. Acked-by: Paul Moore Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231130185229.2688956-11-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/lsm_hook_defs.h | 5 +++-- include/linux/security.h | 6 ++++-- kernel/bpf/bpf_lsm.c | 6 +++--- kernel/bpf/syscall.c | 4 ++-- security/security.c | 16 ++++++++++------ security/selinux/hooks.c | 7 ++++--- 6 files changed, 26 insertions(+), 18 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 41ec4a7c070e..adb25cc63ce3 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -398,8 +398,9 @@ LSM_HOOK(void, LSM_RET_VOID, audit_rule_free, void *lsmrule) LSM_HOOK(int, 0, bpf, int cmd, union bpf_attr *attr, unsigned int size) LSM_HOOK(int, 0, bpf_map, struct bpf_map *map, fmode_t fmode) LSM_HOOK(int, 0, bpf_prog, struct bpf_prog *prog) -LSM_HOOK(int, 0, bpf_map_alloc_security, struct bpf_map *map) -LSM_HOOK(void, LSM_RET_VOID, bpf_map_free_security, struct bpf_map *map) +LSM_HOOK(int, 0, bpf_map_create, struct bpf_map *map, union bpf_attr *attr, + struct bpf_token *token) +LSM_HOOK(void, LSM_RET_VOID, bpf_map_free, struct bpf_map *map) LSM_HOOK(int, 0, bpf_prog_load, struct bpf_prog *prog, union bpf_attr *attr, struct bpf_token *token) LSM_HOOK(void, LSM_RET_VOID, bpf_prog_free, struct bpf_prog *prog) diff --git a/include/linux/security.h b/include/linux/security.h index 65467eef6678..08fd777cbe94 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -2025,7 +2025,8 @@ struct bpf_token; extern int security_bpf(int cmd, union bpf_attr *attr, unsigned int size); extern int security_bpf_map(struct bpf_map *map, fmode_t fmode); extern int security_bpf_prog(struct bpf_prog *prog); -extern int security_bpf_map_alloc(struct bpf_map *map); +extern int security_bpf_map_create(struct bpf_map *map, union bpf_attr *attr, + struct bpf_token *token); extern void security_bpf_map_free(struct bpf_map *map); extern int security_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, struct bpf_token *token); @@ -2047,7 +2048,8 @@ static inline int security_bpf_prog(struct bpf_prog *prog) return 0; } -static inline int security_bpf_map_alloc(struct bpf_map *map) +static inline int security_bpf_map_create(struct bpf_map *map, union bpf_attr *attr, + struct bpf_token *token) { return 0; } diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index 3e956f6302f3..9e4e615f11eb 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -260,8 +260,8 @@ bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) BTF_SET_START(sleepable_lsm_hooks) BTF_ID(func, bpf_lsm_bpf) BTF_ID(func, bpf_lsm_bpf_map) -BTF_ID(func, bpf_lsm_bpf_map_alloc_security) -BTF_ID(func, bpf_lsm_bpf_map_free_security) +BTF_ID(func, bpf_lsm_bpf_map_create) +BTF_ID(func, bpf_lsm_bpf_map_free) BTF_ID(func, bpf_lsm_bpf_prog) BTF_ID(func, bpf_lsm_bpf_prog_load) BTF_ID(func, bpf_lsm_bpf_prog_free) @@ -347,7 +347,7 @@ BTF_ID(func, bpf_lsm_userns_create) BTF_SET_END(sleepable_lsm_hooks) BTF_SET_START(untrusted_lsm_hooks) -BTF_ID(func, bpf_lsm_bpf_map_free_security) +BTF_ID(func, bpf_lsm_bpf_map_free) BTF_ID(func, bpf_lsm_bpf_prog_free) BTF_ID(func, bpf_lsm_file_alloc_security) BTF_ID(func, bpf_lsm_file_free_security) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 7717c7c7b95d..aff045eed375 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1309,9 +1309,9 @@ static int map_create(union bpf_attr *attr) attr->btf_vmlinux_value_type_id; } - err = security_bpf_map_alloc(map); + err = security_bpf_map_create(map, attr, token); if (err) - goto free_map; + goto free_map_sec; err = bpf_map_alloc_id(map); if (err) diff --git a/security/security.c b/security/security.c index c8a1c66cfaad..ad24cf36da94 100644 --- a/security/security.c +++ b/security/security.c @@ -5167,16 +5167,20 @@ int security_bpf_prog(struct bpf_prog *prog) } /** - * security_bpf_map_alloc() - Allocate a bpf map LSM blob - * @map: bpf map + * security_bpf_map_create() - Check if BPF map creation is allowed + * @map: BPF map object + * @attr: BPF syscall attributes used to create BPF map + * @token: BPF token used to grant user access * - * Initialize the security field inside bpf map. + * Do a check when the kernel creates a new BPF map. This is also the + * point where LSM blob is allocated for LSMs that need them. * * Return: Returns 0 on success, error on failure. */ -int security_bpf_map_alloc(struct bpf_map *map) +int security_bpf_map_create(struct bpf_map *map, union bpf_attr *attr, + struct bpf_token *token) { - return call_int_hook(bpf_map_alloc_security, 0, map); + return call_int_hook(bpf_map_create, 0, map, attr, token); } /** @@ -5205,7 +5209,7 @@ int security_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, */ void security_bpf_map_free(struct bpf_map *map) { - call_void_hook(bpf_map_free_security, map); + call_void_hook(bpf_map_free, map); } /** diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index eabee39e983c..002351ab67b7 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -6783,7 +6783,8 @@ static int selinux_bpf_prog(struct bpf_prog *prog) BPF__PROG_RUN, NULL); } -static int selinux_bpf_map_alloc(struct bpf_map *map) +static int selinux_bpf_map_create(struct bpf_map *map, union bpf_attr *attr, + struct bpf_token *token) { struct bpf_security_struct *bpfsec; @@ -7180,7 +7181,7 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = { LSM_HOOK_INIT(bpf, selinux_bpf), LSM_HOOK_INIT(bpf_map, selinux_bpf_map), LSM_HOOK_INIT(bpf_prog, selinux_bpf_prog), - LSM_HOOK_INIT(bpf_map_free_security, selinux_bpf_map_free), + LSM_HOOK_INIT(bpf_map_free, selinux_bpf_map_free), LSM_HOOK_INIT(bpf_prog_free, selinux_bpf_prog_free), #endif @@ -7238,7 +7239,7 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = { LSM_HOOK_INIT(audit_rule_init, selinux_audit_rule_init), #endif #ifdef CONFIG_BPF_SYSCALL - LSM_HOOK_INIT(bpf_map_alloc_security, selinux_bpf_map_alloc), + LSM_HOOK_INIT(bpf_map_create, selinux_bpf_map_create), LSM_HOOK_INIT(bpf_prog_load, selinux_bpf_prog_load), #endif #ifdef CONFIG_PERF_EVENTS -- cgit v1.2.3 From d734ca7b33dbf60eb15dcf7c44f3da7073356777 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 30 Nov 2023 10:52:23 -0800 Subject: bpf,lsm: add BPF token LSM hooks Wire up bpf_token_create and bpf_token_free LSM hooks, which allow to allocate LSM security blob (we add `void *security` field to struct bpf_token for that), but also control who can instantiate BPF token. This follows existing pattern for BPF map and BPF prog. Also add security_bpf_token_allow_cmd() and security_bpf_token_capable() LSM hooks that allow LSM implementation to control and negate (if necessary) BPF token's delegation of a specific bpf_cmd and capability, respectively. Acked-by: Paul Moore Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231130185229.2688956-12-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 3 +++ include/linux/lsm_hook_defs.h | 5 ++++ include/linux/security.h | 25 ++++++++++++++++++ kernel/bpf/bpf_lsm.c | 4 +++ kernel/bpf/token.c | 18 ++++++++----- security/security.c | 60 +++++++++++++++++++++++++++++++++++++++++++ 6 files changed, 109 insertions(+), 6 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 435abad3cc61..7a483f6b6d5f 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1604,6 +1604,9 @@ struct bpf_token { u64 allowed_maps; u64 allowed_progs; u64 allowed_attachs; +#ifdef CONFIG_SECURITY + void *security; +#endif }; struct bpf_struct_ops_value; diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index adb25cc63ce3..3fdd00b452ac 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -404,6 +404,11 @@ LSM_HOOK(void, LSM_RET_VOID, bpf_map_free, struct bpf_map *map) LSM_HOOK(int, 0, bpf_prog_load, struct bpf_prog *prog, union bpf_attr *attr, struct bpf_token *token) LSM_HOOK(void, LSM_RET_VOID, bpf_prog_free, struct bpf_prog *prog) +LSM_HOOK(int, 0, bpf_token_create, struct bpf_token *token, union bpf_attr *attr, + struct path *path) +LSM_HOOK(void, LSM_RET_VOID, bpf_token_free, struct bpf_token *token) +LSM_HOOK(int, 0, bpf_token_cmd, const struct bpf_token *token, enum bpf_cmd cmd) +LSM_HOOK(int, 0, bpf_token_capable, const struct bpf_token *token, int cap) #endif /* CONFIG_BPF_SYSCALL */ LSM_HOOK(int, 0, locked_down, enum lockdown_reason what) diff --git a/include/linux/security.h b/include/linux/security.h index 08fd777cbe94..00809d2d5c38 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -32,6 +32,7 @@ #include #include #include +#include struct linux_binprm; struct cred; @@ -2031,6 +2032,11 @@ extern void security_bpf_map_free(struct bpf_map *map); extern int security_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, struct bpf_token *token); extern void security_bpf_prog_free(struct bpf_prog *prog); +extern int security_bpf_token_create(struct bpf_token *token, union bpf_attr *attr, + struct path *path); +extern void security_bpf_token_free(struct bpf_token *token); +extern int security_bpf_token_cmd(const struct bpf_token *token, enum bpf_cmd cmd); +extern int security_bpf_token_capable(const struct bpf_token *token, int cap); #else static inline int security_bpf(int cmd, union bpf_attr *attr, unsigned int size) @@ -2065,6 +2071,25 @@ static inline int security_bpf_prog_load(struct bpf_prog *prog, union bpf_attr * static inline void security_bpf_prog_free(struct bpf_prog *prog) { } + +static inline int security_bpf_token_create(struct bpf_token *token, union bpf_attr *attr, + struct path *path) +{ + return 0; +} + +static inline void security_bpf_token_free(struct bpf_token *token) +{ } + +static inline int security_bpf_token_cmd(const struct bpf_token *token, enum bpf_cmd cmd) +{ + return 0; +} + +static inline int security_bpf_token_capable(const struct bpf_token *token, int cap) +{ + return 0; +} #endif /* CONFIG_SECURITY */ #endif /* CONFIG_BPF_SYSCALL */ diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index 9e4e615f11eb..7d2f96413a57 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -265,6 +265,10 @@ BTF_ID(func, bpf_lsm_bpf_map_free) BTF_ID(func, bpf_lsm_bpf_prog) BTF_ID(func, bpf_lsm_bpf_prog_load) BTF_ID(func, bpf_lsm_bpf_prog_free) +BTF_ID(func, bpf_lsm_bpf_token_create) +BTF_ID(func, bpf_lsm_bpf_token_free) +BTF_ID(func, bpf_lsm_bpf_token_cmd) +BTF_ID(func, bpf_lsm_bpf_token_capable) BTF_ID(func, bpf_lsm_bprm_check_security) BTF_ID(func, bpf_lsm_bprm_committed_creds) BTF_ID(func, bpf_lsm_bprm_committing_creds) diff --git a/kernel/bpf/token.c b/kernel/bpf/token.c index 5a51e6b8f6bf..17212efcde60 100644 --- a/kernel/bpf/token.c +++ b/kernel/bpf/token.c @@ -7,6 +7,7 @@ #include #include #include +#include bool bpf_token_capable(const struct bpf_token *token, int cap) { @@ -14,10 +15,9 @@ bool bpf_token_capable(const struct bpf_token *token, int cap) * token's userns is *exactly* the same as current user's userns */ if (token && current_user_ns() == token->userns) { - if (ns_capable(token->userns, cap)) - return true; - if (cap != CAP_SYS_ADMIN && ns_capable(token->userns, CAP_SYS_ADMIN)) - return true; + if (ns_capable(token->userns, cap) || + (cap != CAP_SYS_ADMIN && ns_capable(token->userns, CAP_SYS_ADMIN))) + return security_bpf_token_capable(token, cap) == 0; } /* otherwise fallback to capable() checks */ return capable(cap) || (cap != CAP_SYS_ADMIN && capable(CAP_SYS_ADMIN)); @@ -30,6 +30,7 @@ void bpf_token_inc(struct bpf_token *token) static void bpf_token_free(struct bpf_token *token) { + security_bpf_token_free(token); put_user_ns(token->userns); kvfree(token); } @@ -186,6 +187,10 @@ int bpf_token_create(union bpf_attr *attr) token->allowed_progs = mnt_opts->delegate_progs; token->allowed_attachs = mnt_opts->delegate_attachs; + err = security_bpf_token_create(token, attr, &path); + if (err) + goto out_token; + fd = get_unused_fd_flags(O_CLOEXEC); if (fd < 0) { err = fd; @@ -233,8 +238,9 @@ bool bpf_token_allow_cmd(const struct bpf_token *token, enum bpf_cmd cmd) */ if (!token || current_user_ns() != token->userns) return false; - - return token->allowed_cmds & (1ULL << cmd); + if (!(token->allowed_cmds & (1ULL << cmd))) + return false; + return security_bpf_token_cmd(token, cmd) == 0; } bool bpf_token_allow_map_type(const struct bpf_token *token, enum bpf_map_type type) diff --git a/security/security.c b/security/security.c index ad24cf36da94..088a79c35c26 100644 --- a/security/security.c +++ b/security/security.c @@ -5201,6 +5201,55 @@ int security_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, return call_int_hook(bpf_prog_load, 0, prog, attr, token); } +/** + * security_bpf_token_create() - Check if creating of BPF token is allowed + * @token: BPF token object + * @attr: BPF syscall attributes used to create BPF token + * @path: path pointing to BPF FS mount point from which BPF token is created + * + * Do a check when the kernel instantiates a new BPF token object from BPF FS + * instance. This is also the point where LSM blob can be allocated for LSMs. + * + * Return: Returns 0 on success, error on failure. + */ +int security_bpf_token_create(struct bpf_token *token, union bpf_attr *attr, + struct path *path) +{ + return call_int_hook(bpf_token_create, 0, token, attr, path); +} + +/** + * security_bpf_token_cmd() - Check if BPF token is allowed to delegate + * requested BPF syscall command + * @token: BPF token object + * @cmd: BPF syscall command requested to be delegated by BPF token + * + * Do a check when the kernel decides whether provided BPF token should allow + * delegation of requested BPF syscall command. + * + * Return: Returns 0 on success, error on failure. + */ +int security_bpf_token_cmd(const struct bpf_token *token, enum bpf_cmd cmd) +{ + return call_int_hook(bpf_token_cmd, 0, token, cmd); +} + +/** + * security_bpf_token_capable() - Check if BPF token is allowed to delegate + * requested BPF-related capability + * @token: BPF token object + * @cap: capabilities requested to be delegated by BPF token + * + * Do a check when the kernel decides whether provided BPF token should allow + * delegation of requested BPF-related capabilities. + * + * Return: Returns 0 on success, error on failure. + */ +int security_bpf_token_capable(const struct bpf_token *token, int cap) +{ + return call_int_hook(bpf_token_capable, 0, token, cap); +} + /** * security_bpf_map_free() - Free a bpf map's LSM blob * @map: bpf map @@ -5222,6 +5271,17 @@ void security_bpf_prog_free(struct bpf_prog *prog) { call_void_hook(bpf_prog_free, prog); } + +/** + * security_bpf_token_free() - Free a BPF token's LSM blob + * @token: BPF token struct + * + * Clean up the security information stored inside BPF token. + */ +void security_bpf_token_free(struct bpf_token *token) +{ + call_void_hook(bpf_token_free, token); +} #endif /* CONFIG_BPF_SYSCALL */ /** -- cgit v1.2.3 From 4b7de801606e504e69689df71475d27e35336fb3 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 6 Dec 2023 09:30:40 +0100 Subject: bpf: Fix prog_array_map_poke_run map poke update Lee pointed out issue found by syscaller [0] hitting BUG in prog array map poke update in prog_array_map_poke_run function due to error value returned from bpf_arch_text_poke function. There's race window where bpf_arch_text_poke can fail due to missing bpf program kallsym symbols, which is accounted for with check for -EINVAL in that BUG_ON call. The problem is that in such case we won't update the tail call jump and cause imbalance for the next tail call update check which will fail with -EBUSY in bpf_arch_text_poke. I'm hitting following race during the program load: CPU 0 CPU 1 bpf_prog_load bpf_check do_misc_fixups prog_array_map_poke_track map_update_elem bpf_fd_array_map_update_elem prog_array_map_poke_run bpf_arch_text_poke returns -EINVAL bpf_prog_kallsyms_add After bpf_arch_text_poke (CPU 1) fails to update the tail call jump, the next poke update fails on expected jump instruction check in bpf_arch_text_poke with -EBUSY and triggers the BUG_ON in prog_array_map_poke_run. Similar race exists on the program unload. Fixing this by moving the update to bpf_arch_poke_desc_update function which makes sure we call __bpf_arch_text_poke that skips the bpf address check. Each architecture has slightly different approach wrt looking up bpf address in bpf_arch_text_poke, so instead of splitting the function or adding new 'checkip' argument in previous version, it seems best to move the whole map_poke_run update as arch specific code. [0] https://syzkaller.appspot.com/bug?extid=97a4fe20470e9bc30810 Fixes: ebf7d1f508a7 ("bpf, x64: rework pro/epilogue and tailcall handling in JIT") Reported-by: syzbot+97a4fe20470e9bc30810@syzkaller.appspotmail.com Signed-off-by: Jiri Olsa Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Cc: Lee Jones Cc: Maciej Fijalkowski Link: https://lore.kernel.org/bpf/20231206083041.1306660-2-jolsa@kernel.org --- arch/x86/net/bpf_jit_comp.c | 46 +++++++++++++++++++++++++++++++++++ include/linux/bpf.h | 3 +++ kernel/bpf/arraymap.c | 58 ++++++++------------------------------------- 3 files changed, 59 insertions(+), 48 deletions(-) (limited to 'kernel/bpf') diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 8c10d9abc239..e89e415aa743 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -3025,3 +3025,49 @@ void arch_bpf_stack_walk(bool (*consume_fn)(void *cookie, u64 ip, u64 sp, u64 bp #endif WARN(1, "verification of programs using bpf_throw should have failed\n"); } + +void bpf_arch_poke_desc_update(struct bpf_jit_poke_descriptor *poke, + struct bpf_prog *new, struct bpf_prog *old) +{ + u8 *old_addr, *new_addr, *old_bypass_addr; + int ret; + + old_bypass_addr = old ? NULL : poke->bypass_addr; + old_addr = old ? (u8 *)old->bpf_func + poke->adj_off : NULL; + new_addr = new ? (u8 *)new->bpf_func + poke->adj_off : NULL; + + /* + * On program loading or teardown, the program's kallsym entry + * might not be in place, so we use __bpf_arch_text_poke to skip + * the kallsyms check. + */ + if (new) { + ret = __bpf_arch_text_poke(poke->tailcall_target, + BPF_MOD_JUMP, + old_addr, new_addr); + BUG_ON(ret < 0); + if (!old) { + ret = __bpf_arch_text_poke(poke->tailcall_bypass, + BPF_MOD_JUMP, + poke->bypass_addr, + NULL); + BUG_ON(ret < 0); + } + } else { + ret = __bpf_arch_text_poke(poke->tailcall_bypass, + BPF_MOD_JUMP, + old_bypass_addr, + poke->bypass_addr); + BUG_ON(ret < 0); + /* let other CPUs finish the execution of program + * so that it will not possible to expose them + * to invalid nop, stack unwind, nop state + */ + if (!ret) + synchronize_rcu(); + ret = __bpf_arch_text_poke(poke->tailcall_target, + BPF_MOD_JUMP, + old_addr, NULL); + BUG_ON(ret < 0); + } +} diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 6762dac3ef76..cff5bb08820e 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -3175,6 +3175,9 @@ enum bpf_text_poke_type { int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, void *addr1, void *addr2); +void bpf_arch_poke_desc_update(struct bpf_jit_poke_descriptor *poke, + struct bpf_prog *new, struct bpf_prog *old); + void *bpf_arch_text_copy(void *dst, void *src, size_t len); int bpf_arch_text_invalidate(void *dst, size_t len); diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 2058e89b5ddd..c85ff9162a5c 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -1012,11 +1012,16 @@ static void prog_array_map_poke_untrack(struct bpf_map *map, mutex_unlock(&aux->poke_mutex); } +void __weak bpf_arch_poke_desc_update(struct bpf_jit_poke_descriptor *poke, + struct bpf_prog *new, struct bpf_prog *old) +{ + WARN_ON_ONCE(1); +} + static void prog_array_map_poke_run(struct bpf_map *map, u32 key, struct bpf_prog *old, struct bpf_prog *new) { - u8 *old_addr, *new_addr, *old_bypass_addr; struct prog_poke_elem *elem; struct bpf_array_aux *aux; @@ -1025,7 +1030,7 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key, list_for_each_entry(elem, &aux->poke_progs, list) { struct bpf_jit_poke_descriptor *poke; - int i, ret; + int i; for (i = 0; i < elem->aux->size_poke_tab; i++) { poke = &elem->aux->poke_tab[i]; @@ -1044,21 +1049,10 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key, * activated, so tail call updates can arrive from here * while JIT is still finishing its final fixup for * non-activated poke entries. - * 3) On program teardown, the program's kallsym entry gets - * removed out of RCU callback, but we can only untrack - * from sleepable context, therefore bpf_arch_text_poke() - * might not see that this is in BPF text section and - * bails out with -EINVAL. As these are unreachable since - * RCU grace period already passed, we simply skip them. - * 4) Also programs reaching refcount of zero while patching + * 3) Also programs reaching refcount of zero while patching * is in progress is okay since we're protected under * poke_mutex and untrack the programs before the JIT - * buffer is freed. When we're still in the middle of - * patching and suddenly kallsyms entry of the program - * gets evicted, we just skip the rest which is fine due - * to point 3). - * 5) Any other error happening below from bpf_arch_text_poke() - * is a unexpected bug. + * buffer is freed. */ if (!READ_ONCE(poke->tailcall_target_stable)) continue; @@ -1068,39 +1062,7 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key, poke->tail_call.key != key) continue; - old_bypass_addr = old ? NULL : poke->bypass_addr; - old_addr = old ? (u8 *)old->bpf_func + poke->adj_off : NULL; - new_addr = new ? (u8 *)new->bpf_func + poke->adj_off : NULL; - - if (new) { - ret = bpf_arch_text_poke(poke->tailcall_target, - BPF_MOD_JUMP, - old_addr, new_addr); - BUG_ON(ret < 0 && ret != -EINVAL); - if (!old) { - ret = bpf_arch_text_poke(poke->tailcall_bypass, - BPF_MOD_JUMP, - poke->bypass_addr, - NULL); - BUG_ON(ret < 0 && ret != -EINVAL); - } - } else { - ret = bpf_arch_text_poke(poke->tailcall_bypass, - BPF_MOD_JUMP, - old_bypass_addr, - poke->bypass_addr); - BUG_ON(ret < 0 && ret != -EINVAL); - /* let other CPUs finish the execution of program - * so that it will not possible to expose them - * to invalid nop, stack unwind, nop state - */ - if (!ret) - synchronize_rcu(); - ret = bpf_arch_text_poke(poke->tailcall_target, - BPF_MOD_JUMP, - old_addr, NULL); - BUG_ON(ret < 0 && ret != -EINVAL); - } + bpf_arch_poke_desc_update(poke, new, old); } } } -- cgit v1.2.3 From f08a1c658257c73697a819c4ded3a84b6f0ead74 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Wed, 6 Dec 2023 14:40:48 -0800 Subject: bpf: Let bpf_prog_pack_free handle any pointer MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Currently, bpf_prog_pack_free only can only free pointer to struct bpf_binary_header, which is not flexible. Add a size argument to bpf_prog_pack_free so that it can handle any pointer. Signed-off-by: Song Liu Acked-by: Ilya Leoshkevich Tested-by: Ilya Leoshkevich # on s390x Reviewed-by: Björn Töpel Acked-by: Jiri Olsa Link: https://lore.kernel.org/r/20231206224054.492250-2-song@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/filter.h | 2 +- kernel/bpf/core.c | 21 ++++++++++----------- kernel/bpf/dispatcher.c | 5 +---- 3 files changed, 12 insertions(+), 16 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/filter.h b/include/linux/filter.h index 14354605ad26..12d907f17d36 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -1067,7 +1067,7 @@ struct bpf_binary_header * bpf_jit_binary_pack_hdr(const struct bpf_prog *fp); void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns); -void bpf_prog_pack_free(struct bpf_binary_header *hdr); +void bpf_prog_pack_free(void *ptr, u32 size); static inline bool bpf_prog_kallsyms_verify_off(const struct bpf_prog *fp) { diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index ced511f44174..c34513d645c4 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -928,20 +928,20 @@ out: return ptr; } -void bpf_prog_pack_free(struct bpf_binary_header *hdr) +void bpf_prog_pack_free(void *ptr, u32 size) { struct bpf_prog_pack *pack = NULL, *tmp; unsigned int nbits; unsigned long pos; mutex_lock(&pack_mutex); - if (hdr->size > BPF_PROG_PACK_SIZE) { - bpf_jit_free_exec(hdr); + if (size > BPF_PROG_PACK_SIZE) { + bpf_jit_free_exec(ptr); goto out; } list_for_each_entry(tmp, &pack_list, list) { - if ((void *)hdr >= tmp->ptr && (tmp->ptr + BPF_PROG_PACK_SIZE) > (void *)hdr) { + if (ptr >= tmp->ptr && (tmp->ptr + BPF_PROG_PACK_SIZE) > ptr) { pack = tmp; break; } @@ -950,10 +950,10 @@ void bpf_prog_pack_free(struct bpf_binary_header *hdr) if (WARN_ONCE(!pack, "bpf_prog_pack bug\n")) goto out; - nbits = BPF_PROG_SIZE_TO_NBITS(hdr->size); - pos = ((unsigned long)hdr - (unsigned long)pack->ptr) >> BPF_PROG_CHUNK_SHIFT; + nbits = BPF_PROG_SIZE_TO_NBITS(size); + pos = ((unsigned long)ptr - (unsigned long)pack->ptr) >> BPF_PROG_CHUNK_SHIFT; - WARN_ONCE(bpf_arch_text_invalidate(hdr, hdr->size), + WARN_ONCE(bpf_arch_text_invalidate(ptr, size), "bpf_prog_pack bug: missing bpf_arch_text_invalidate?\n"); bitmap_clear(pack->bitmap, pos, nbits); @@ -1100,8 +1100,7 @@ bpf_jit_binary_pack_alloc(unsigned int proglen, u8 **image_ptr, *rw_header = kvmalloc(size, GFP_KERNEL); if (!*rw_header) { - bpf_arch_text_copy(&ro_header->size, &size, sizeof(size)); - bpf_prog_pack_free(ro_header); + bpf_prog_pack_free(ro_header, size); bpf_jit_uncharge_modmem(size); return NULL; } @@ -1132,7 +1131,7 @@ int bpf_jit_binary_pack_finalize(struct bpf_prog *prog, kvfree(rw_header); if (IS_ERR(ptr)) { - bpf_prog_pack_free(ro_header); + bpf_prog_pack_free(ro_header, ro_header->size); return PTR_ERR(ptr); } return 0; @@ -1153,7 +1152,7 @@ void bpf_jit_binary_pack_free(struct bpf_binary_header *ro_header, { u32 size = ro_header->size; - bpf_prog_pack_free(ro_header); + bpf_prog_pack_free(ro_header, size); kvfree(rw_header); bpf_jit_uncharge_modmem(size); } diff --git a/kernel/bpf/dispatcher.c b/kernel/bpf/dispatcher.c index fa3e9225aedc..56760fc10e78 100644 --- a/kernel/bpf/dispatcher.c +++ b/kernel/bpf/dispatcher.c @@ -150,10 +150,7 @@ void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from, goto out; d->rw_image = bpf_jit_alloc_exec(PAGE_SIZE); if (!d->rw_image) { - u32 size = PAGE_SIZE; - - bpf_arch_text_copy(d->image, &size, sizeof(size)); - bpf_prog_pack_free((struct bpf_binary_header *)d->image); + bpf_prog_pack_free(d->image, PAGE_SIZE); d->image = NULL; goto out; } -- cgit v1.2.3 From 7a3d9a159b178e87306a6e989071ed9a114a1a31 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Wed, 6 Dec 2023 14:40:49 -0800 Subject: bpf: Adjust argument names of arch_prepare_bpf_trampoline() We are using "im" for "struct bpf_tramp_image" and "tr" for "struct bpf_trampoline" in most of the code base. The only exception is the prototype and fallback version of arch_prepare_bpf_trampoline(). Update them to match the rest of the code base. We mix "orig_call" and "func_addr" for the argument in different versions of arch_prepare_bpf_trampoline(). s/orig_call/func_addr/g so they match. Signed-off-by: Song Liu Acked-by: Ilya Leoshkevich Tested-by: Ilya Leoshkevich # on s390x Acked-by: Jiri Olsa Link: https://lore.kernel.org/r/20231206224054.492250-3-song@kernel.org Signed-off-by: Alexei Starovoitov --- arch/arm64/net/bpf_jit_comp.c | 10 +++++----- include/linux/bpf.h | 4 ++-- kernel/bpf/trampoline.c | 4 ++-- 3 files changed, 9 insertions(+), 9 deletions(-) (limited to 'kernel/bpf') diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 7d4af64e3982..d81b886ea4df 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -1828,7 +1828,7 @@ static void restore_args(struct jit_ctx *ctx, int args_off, int nregs) * */ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, - struct bpf_tramp_links *tlinks, void *orig_call, + struct bpf_tramp_links *tlinks, void *func_addr, int nregs, u32 flags) { int i; @@ -1926,7 +1926,7 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, if (flags & BPF_TRAMP_F_IP_ARG) { /* save ip address of the traced function */ - emit_addr_mov_i64(A64_R(10), (const u64)orig_call, ctx); + emit_addr_mov_i64(A64_R(10), (const u64)func_addr, ctx); emit(A64_STR64I(A64_R(10), A64_SP, ip_off), ctx); } @@ -2029,7 +2029,7 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end, const struct btf_func_model *m, u32 flags, struct bpf_tramp_links *tlinks, - void *orig_call) + void *func_addr) { int i, ret; int nregs = m->nr_args; @@ -2050,7 +2050,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, if (nregs > 8) return -ENOTSUPP; - ret = prepare_trampoline(&ctx, im, tlinks, orig_call, nregs, flags); + ret = prepare_trampoline(&ctx, im, tlinks, func_addr, nregs, flags); if (ret < 0) return ret; @@ -2061,7 +2061,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, ctx.idx = 0; jit_fill_hole(image, (unsigned int)(image_end - image)); - ret = prepare_trampoline(&ctx, im, tlinks, orig_call, nregs, flags); + ret = prepare_trampoline(&ctx, im, tlinks, func_addr, nregs, flags); if (ret > 0 && validate_code(&ctx) < 0) ret = -EINVAL; diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 7a483f6b6d5f..17eb6d905204 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1098,10 +1098,10 @@ struct bpf_tramp_run_ctx; * fexit = a set of program to run after original function */ struct bpf_tramp_image; -int arch_prepare_bpf_trampoline(struct bpf_tramp_image *tr, void *image, void *image_end, +int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end, const struct btf_func_model *m, u32 flags, struct bpf_tramp_links *tlinks, - void *orig_call); + void *func_addr); u64 notrace __bpf_prog_enter_sleepable_recur(struct bpf_prog *prog, struct bpf_tramp_run_ctx *run_ctx); void notrace __bpf_prog_exit_sleepable_recur(struct bpf_prog *prog, u64 start, diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index e97aeda3a86b..e114a1c7961e 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -1032,10 +1032,10 @@ bpf_trampoline_exit_t bpf_trampoline_exit(const struct bpf_prog *prog) } int __weak -arch_prepare_bpf_trampoline(struct bpf_tramp_image *tr, void *image, void *image_end, +arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end, const struct btf_func_model *m, u32 flags, struct bpf_tramp_links *tlinks, - void *orig_call) + void *func_addr) { return -ENOTSUPP; } -- cgit v1.2.3 From 82583daa2efc2e336962b231a46bad03a280b3e0 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Wed, 6 Dec 2023 14:40:50 -0800 Subject: bpf: Add helpers for trampoline image management As BPF trampoline of different archs moves from bpf_jit_[alloc|free]_exec() to bpf_prog_pack_[alloc|free](), we need to use different _alloc, _free for different archs during the transition. Add the following helpers for this transition: void *arch_alloc_bpf_trampoline(unsigned int size); void arch_free_bpf_trampoline(void *image, unsigned int size); void arch_protect_bpf_trampoline(void *image, unsigned int size); void arch_unprotect_bpf_trampoline(void *image, unsigned int size); The fallback version of these helpers require size <= PAGE_SIZE, but they are only called with size == PAGE_SIZE. They will be called with size < PAGE_SIZE when arch_bpf_trampoline_size() helper is introduced later. Signed-off-by: Song Liu Acked-by: Ilya Leoshkevich Tested-by: Ilya Leoshkevich # on s390x Acked-by: Jiri Olsa Link: https://lore.kernel.org/r/20231206224054.492250-4-song@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 5 +++++ kernel/bpf/bpf_struct_ops.c | 12 +++++------ kernel/bpf/trampoline.c | 46 +++++++++++++++++++++++++++++++++++------- net/bpf/bpf_dummy_struct_ops.c | 7 +++---- 4 files changed, 52 insertions(+), 18 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 17eb6d905204..b7fca151cf1b 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1102,6 +1102,11 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i const struct btf_func_model *m, u32 flags, struct bpf_tramp_links *tlinks, void *func_addr); +void *arch_alloc_bpf_trampoline(unsigned int size); +void arch_free_bpf_trampoline(void *image, unsigned int size); +void arch_protect_bpf_trampoline(void *image, unsigned int size); +void arch_unprotect_bpf_trampoline(void *image, unsigned int size); + u64 notrace __bpf_prog_enter_sleepable_recur(struct bpf_prog *prog, struct bpf_tramp_run_ctx *run_ctx); void notrace __bpf_prog_exit_sleepable_recur(struct bpf_prog *prog, u64 start, diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index db6176fb64dc..e9e95879bce2 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -515,7 +515,7 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, if (err) goto reset_unlock; } - set_memory_rox((long)st_map->image, 1); + arch_protect_bpf_trampoline(st_map->image, PAGE_SIZE); /* Let bpf_link handle registration & unregistration. * * Pair with smp_load_acquire() during lookup_elem(). @@ -524,7 +524,7 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, goto unlock; } - set_memory_rox((long)st_map->image, 1); + arch_protect_bpf_trampoline(st_map->image, PAGE_SIZE); err = st_ops->reg(kdata); if (likely(!err)) { /* This refcnt increment on the map here after @@ -547,8 +547,7 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, * there was a race in registering the struct_ops (under the same name) to * a sub-system through different struct_ops's maps. */ - set_memory_nx((long)st_map->image, 1); - set_memory_rw((long)st_map->image, 1); + arch_unprotect_bpf_trampoline(st_map->image, PAGE_SIZE); reset_unlock: bpf_struct_ops_map_put_progs(st_map); @@ -616,7 +615,7 @@ static void __bpf_struct_ops_map_free(struct bpf_map *map) bpf_struct_ops_map_put_progs(st_map); bpf_map_area_free(st_map->links); if (st_map->image) { - bpf_jit_free_exec(st_map->image); + arch_free_bpf_trampoline(st_map->image, PAGE_SIZE); bpf_jit_uncharge_modmem(PAGE_SIZE); } bpf_map_area_free(st_map->uvalue); @@ -691,7 +690,7 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) return ERR_PTR(ret); } - st_map->image = bpf_jit_alloc_exec(PAGE_SIZE); + st_map->image = arch_alloc_bpf_trampoline(PAGE_SIZE); if (!st_map->image) { /* __bpf_struct_ops_map_free() uses st_map->image as flag * for "charged or not". In this case, we need to unchange @@ -711,7 +710,6 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) } mutex_init(&st_map->lock); - set_vm_flush_reset_perms(st_map->image); bpf_map_init_from_attr(map, attr); return map; diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index e114a1c7961e..affbcbf7e76e 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -254,7 +254,7 @@ bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total, bool *ip_a static void bpf_tramp_image_free(struct bpf_tramp_image *im) { bpf_image_ksym_del(&im->ksym); - bpf_jit_free_exec(im->image); + arch_free_bpf_trampoline(im->image, PAGE_SIZE); bpf_jit_uncharge_modmem(PAGE_SIZE); percpu_ref_exit(&im->pcref); kfree_rcu(im, rcu); @@ -365,10 +365,9 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key) goto out_free_im; err = -ENOMEM; - im->image = image = bpf_jit_alloc_exec(PAGE_SIZE); + im->image = image = arch_alloc_bpf_trampoline(PAGE_SIZE); if (!image) goto out_uncharge; - set_vm_flush_reset_perms(image); err = percpu_ref_init(&im->pcref, __bpf_tramp_image_release, 0, GFP_KERNEL); if (err) @@ -381,7 +380,7 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key) return im; out_free_image: - bpf_jit_free_exec(im->image); + arch_free_bpf_trampoline(im->image, PAGE_SIZE); out_uncharge: bpf_jit_uncharge_modmem(PAGE_SIZE); out_free_im: @@ -444,7 +443,7 @@ again: if (err < 0) goto out_free; - set_memory_rox((long)im->image, 1); + arch_protect_bpf_trampoline(im->image, PAGE_SIZE); WARN_ON(tr->cur_image && total == 0); if (tr->cur_image) @@ -465,8 +464,7 @@ again: tr->fops->trampoline = 0; /* reset im->image memory attr for arch_prepare_bpf_trampoline */ - set_memory_nx((long)im->image, 1); - set_memory_rw((long)im->image, 1); + arch_unprotect_bpf_trampoline(im->image, PAGE_SIZE); goto again; } #endif @@ -1040,6 +1038,40 @@ arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image return -ENOTSUPP; } +void * __weak arch_alloc_bpf_trampoline(unsigned int size) +{ + void *image; + + if (WARN_ON_ONCE(size > PAGE_SIZE)) + return NULL; + image = bpf_jit_alloc_exec(PAGE_SIZE); + if (image) + set_vm_flush_reset_perms(image); + return image; +} + +void __weak arch_free_bpf_trampoline(void *image, unsigned int size) +{ + WARN_ON_ONCE(size > PAGE_SIZE); + /* bpf_jit_free_exec doesn't need "size", but + * bpf_prog_pack_free() needs it. + */ + bpf_jit_free_exec(image); +} + +void __weak arch_protect_bpf_trampoline(void *image, unsigned int size) +{ + WARN_ON_ONCE(size > PAGE_SIZE); + set_memory_rox((long)image, 1); +} + +void __weak arch_unprotect_bpf_trampoline(void *image, unsigned int size) +{ + WARN_ON_ONCE(size > PAGE_SIZE); + set_memory_nx((long)image, 1); + set_memory_rw((long)image, 1); +} + static int __init init_trampolines(void) { int i; diff --git a/net/bpf/bpf_dummy_struct_ops.c b/net/bpf/bpf_dummy_struct_ops.c index 5918d1b32e19..2748f9d77b18 100644 --- a/net/bpf/bpf_dummy_struct_ops.c +++ b/net/bpf/bpf_dummy_struct_ops.c @@ -101,12 +101,11 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr, goto out; } - image = bpf_jit_alloc_exec(PAGE_SIZE); + image = arch_alloc_bpf_trampoline(PAGE_SIZE); if (!image) { err = -ENOMEM; goto out; } - set_vm_flush_reset_perms(image); link = kzalloc(sizeof(*link), GFP_USER); if (!link) { @@ -124,7 +123,7 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr, if (err < 0) goto out; - set_memory_rox((long)image, 1); + arch_protect_bpf_trampoline(image, PAGE_SIZE); prog_ret = dummy_ops_call_op(image, args); err = dummy_ops_copy_args(args); @@ -134,7 +133,7 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr, err = -EFAULT; out: kfree(args); - bpf_jit_free_exec(image); + arch_free_bpf_trampoline(image, PAGE_SIZE); if (link) bpf_link_put(&link->link); kfree(tlinks); -- cgit v1.2.3 From 96d1b7c081c0c96cbe8901045f4ff15a2e9974a2 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Wed, 6 Dec 2023 14:40:52 -0800 Subject: bpf: Add arch_bpf_trampoline_size() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This helper will be used to calculate the size of the trampoline before allocating the memory. arch_prepare_bpf_trampoline() for arm64 and riscv64 can use arch_bpf_trampoline_size() to check the trampoline fits in the image. OTOH, arch_prepare_bpf_trampoline() for s390 has to call the JIT process twice, so it cannot use arch_bpf_trampoline_size(). Signed-off-by: Song Liu Acked-by: Ilya Leoshkevich Tested-by: Ilya Leoshkevich # on s390x Acked-by: Jiri Olsa Acked-by: Björn Töpel Tested-by: Björn Töpel # on riscv Link: https://lore.kernel.org/r/20231206224054.492250-6-song@kernel.org Signed-off-by: Alexei Starovoitov --- arch/arm64/net/bpf_jit_comp.c | 56 ++++++++++++++++++++++++++++++----------- arch/riscv/net/bpf_jit_comp64.c | 22 ++++++++++++---- arch/s390/net/bpf_jit_comp.c | 56 +++++++++++++++++++++++++---------------- arch/x86/net/bpf_jit_comp.c | 40 ++++++++++++++++++++++++++--- include/linux/bpf.h | 2 ++ kernel/bpf/trampoline.c | 6 +++++ 6 files changed, 136 insertions(+), 46 deletions(-) (limited to 'kernel/bpf') diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index d81b886ea4df..a6671253b7ed 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -2026,18 +2026,10 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, return ctx->idx; } -int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, - void *image_end, const struct btf_func_model *m, - u32 flags, struct bpf_tramp_links *tlinks, - void *func_addr) +static int btf_func_model_nregs(const struct btf_func_model *m) { - int i, ret; int nregs = m->nr_args; - int max_insns = ((long)image_end - (long)image) / AARCH64_INSN_SIZE; - struct jit_ctx ctx = { - .image = NULL, - .idx = 0, - }; + int i; /* extra registers needed for struct argument */ for (i = 0; i < MAX_BPF_FUNC_ARGS; i++) { @@ -2046,19 +2038,53 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, nregs += (m->arg_size[i] + 7) / 8 - 1; } + return nregs; +} + +int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, void *func_addr) +{ + struct jit_ctx ctx = { + .image = NULL, + .idx = 0, + }; + struct bpf_tramp_image im; + int nregs, ret; + + nregs = btf_func_model_nregs(m); /* the first 8 registers are used for arguments */ if (nregs > 8) return -ENOTSUPP; - ret = prepare_trampoline(&ctx, im, tlinks, func_addr, nregs, flags); + ret = prepare_trampoline(&ctx, &im, tlinks, func_addr, nregs, flags); if (ret < 0) return ret; - if (ret > max_insns) - return -EFBIG; + return ret < 0 ? ret : ret * AARCH64_INSN_SIZE; +} - ctx.image = image; - ctx.idx = 0; +int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, + void *image_end, const struct btf_func_model *m, + u32 flags, struct bpf_tramp_links *tlinks, + void *func_addr) +{ + int ret, nregs; + struct jit_ctx ctx = { + .image = image, + .idx = 0, + }; + + nregs = btf_func_model_nregs(m); + /* the first 8 registers are used for arguments */ + if (nregs > 8) + return -ENOTSUPP; + + ret = arch_bpf_trampoline_size(m, flags, tlinks, func_addr); + if (ret < 0) + return ret; + + if (ret > ((long)image_end - (long)image)) + return -EFBIG; jit_fill_hole(image, (unsigned int)(image_end - image)); ret = prepare_trampoline(&ctx, im, tlinks, func_addr, nregs, flags); diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c index 8581693e62d3..35747fafde57 100644 --- a/arch/riscv/net/bpf_jit_comp64.c +++ b/arch/riscv/net/bpf_jit_comp64.c @@ -1029,6 +1029,21 @@ out: return ret; } +int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, void *func_addr) +{ + struct bpf_tramp_image im; + struct rv_jit_context ctx; + int ret; + + ctx.ninsns = 0; + ctx.insns = NULL; + ctx.ro_insns = NULL; + ret = __arch_prepare_bpf_trampoline(&im, m, tlinks, func_addr, flags, &ctx); + + return ret < 0 ? ret : ninsns_rvoff(ctx.ninsns); +} + int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end, const struct btf_func_model *m, u32 flags, struct bpf_tramp_links *tlinks, @@ -1037,14 +1052,11 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, int ret; struct rv_jit_context ctx; - ctx.ninsns = 0; - ctx.insns = NULL; - ctx.ro_insns = NULL; - ret = __arch_prepare_bpf_trampoline(im, m, tlinks, func_addr, flags, &ctx); + ret = arch_bpf_trampoline_size(im, m, flags, tlinks, func_addr); if (ret < 0) return ret; - if (ninsns_rvoff(ret) > (long)image_end - (long)image) + if (ret > (long)image_end - (long)image) return -EFBIG; ctx.ninsns = 0; diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index bf06b7283f0c..cc129617480a 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -2637,6 +2637,21 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, return 0; } +int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, void *orig_call) +{ + struct bpf_tramp_image im; + struct bpf_tramp_jit tjit; + int ret; + + memset(&tjit, 0, sizeof(tjit)); + + ret = __arch_prepare_bpf_trampoline(&im, &tjit, m, flags, + tlinks, orig_call); + + return ret < 0 ? ret : tjit.common.prg; +} + int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end, const struct btf_func_model *m, u32 flags, struct bpf_tramp_links *tlinks, @@ -2644,30 +2659,27 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, { struct bpf_tramp_jit tjit; int ret; - int i; - for (i = 0; i < 2; i++) { - if (i == 0) { - /* Compute offsets, check whether the code fits. */ - memset(&tjit, 0, sizeof(tjit)); - } else { - /* Generate the code. */ - tjit.common.prg = 0; - tjit.common.prg_buf = image; - } - ret = __arch_prepare_bpf_trampoline(im, &tjit, m, flags, - tlinks, func_addr); - if (ret < 0) - return ret; - if (tjit.common.prg > (char *)image_end - (char *)image) - /* - * Use the same error code as for exceeding - * BPF_MAX_TRAMP_LINKS. - */ - return -E2BIG; - } + /* Compute offsets, check whether the code fits. */ + memset(&tjit, 0, sizeof(tjit)); + ret = __arch_prepare_bpf_trampoline(im, &tjit, m, flags, + tlinks, func_addr); + + if (ret < 0) + return ret; + if (tjit.common.prg > (char *)image_end - (char *)image) + /* + * Use the same error code as for exceeding + * BPF_MAX_TRAMP_LINKS. + */ + return -E2BIG; + + tjit.common.prg = 0; + tjit.common.prg_buf = image; + ret = __arch_prepare_bpf_trampoline(im, &tjit, m, flags, + tlinks, func_addr); - return tjit.common.prg; + return ret < 0 ? ret : tjit.common.prg; } bool bpf_jit_supports_subprog_tailcalls(void) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 5f7528cac344..5d75069fdcc2 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -2422,10 +2422,10 @@ static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog, * add rsp, 8 // skip eth_type_trans's frame * ret // return to its caller */ -int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end, - const struct btf_func_model *m, u32 flags, - struct bpf_tramp_links *tlinks, - void *func_addr) +static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end, + const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, + void *func_addr) { int i, ret, nr_regs = m->nr_args, stack_size = 0; int regs_off, nregs_off, ip_off, run_ctx_off, arg_stack_off, rbx_off; @@ -2678,6 +2678,38 @@ cleanup: return ret; } +int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end, + const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, + void *func_addr) +{ + return __arch_prepare_bpf_trampoline(im, image, image_end, m, flags, tlinks, func_addr); +} + +int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, void *func_addr) +{ + struct bpf_tramp_image im; + void *image; + int ret; + + /* Allocate a temporary buffer for __arch_prepare_bpf_trampoline(). + * This will NOT cause fragmentation in direct map, as we do not + * call set_memory_*() on this buffer. + * + * We cannot use kvmalloc here, because we need image to be in + * module memory range. + */ + image = bpf_jit_alloc_exec(PAGE_SIZE); + if (!image) + return -ENOMEM; + + ret = __arch_prepare_bpf_trampoline(&im, image, image + PAGE_SIZE, m, flags, + tlinks, func_addr); + bpf_jit_free_exec(image); + return ret; +} + static int emit_bpf_dispatcher(u8 **pprog, int a, int b, s64 *progs, u8 *image, u8 *buf) { u8 *jg_reloc, *prog = *pprog; diff --git a/include/linux/bpf.h b/include/linux/bpf.h index b7fca151cf1b..2332ddeb396b 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1106,6 +1106,8 @@ void *arch_alloc_bpf_trampoline(unsigned int size); void arch_free_bpf_trampoline(void *image, unsigned int size); void arch_protect_bpf_trampoline(void *image, unsigned int size); void arch_unprotect_bpf_trampoline(void *image, unsigned int size); +int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, void *func_addr); u64 notrace __bpf_prog_enter_sleepable_recur(struct bpf_prog *prog, struct bpf_tramp_run_ctx *run_ctx); diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index affbcbf7e76e..b553cbd89e55 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -1072,6 +1072,12 @@ void __weak arch_unprotect_bpf_trampoline(void *image, unsigned int size) set_memory_rw((long)image, 1); } +int __weak arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, void *func_addr) +{ + return -ENOTSUPP; +} + static int __init init_trampolines(void) { int i; -- cgit v1.2.3 From 26ef208c209a0e6eed8942a5d191b39dccfa6e38 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Wed, 6 Dec 2023 14:40:53 -0800 Subject: bpf: Use arch_bpf_trampoline_size MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Instead of blindly allocating PAGE_SIZE for each trampoline, check the size of the trampoline with arch_bpf_trampoline_size(). This size is saved in bpf_tramp_image->size, and used for modmem charge/uncharge. The fallback arch_alloc_bpf_trampoline() still allocates a whole page because we need to use set_memory_* to protect the memory. struct_ops trampoline still uses a whole page for multiple trampolines. With this size check at caller (regular trampoline and struct_ops trampoline), remove arch_bpf_trampoline_size() from arch_prepare_bpf_trampoline() in archs. Also, update bpf_image_ksym_add() to handle symbol of different sizes. Signed-off-by: Song Liu Acked-by: Ilya Leoshkevich Tested-by: Ilya Leoshkevich # on s390x Acked-by: Jiri Olsa Acked-by: Björn Töpel Tested-by: Björn Töpel # on riscv Link: https://lore.kernel.org/r/20231206224054.492250-7-song@kernel.org Signed-off-by: Alexei Starovoitov --- arch/arm64/net/bpf_jit_comp.c | 7 ------ arch/riscv/net/bpf_jit_comp64.c | 7 ------ include/linux/bpf.h | 3 ++- kernel/bpf/bpf_struct_ops.c | 7 ++++++ kernel/bpf/dispatcher.c | 2 +- kernel/bpf/trampoline.c | 55 +++++++++++++++++++++++++---------------- 6 files changed, 44 insertions(+), 37 deletions(-) (limited to 'kernel/bpf') diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index a6671253b7ed..8955da5c47cf 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -2079,13 +2079,6 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, if (nregs > 8) return -ENOTSUPP; - ret = arch_bpf_trampoline_size(m, flags, tlinks, func_addr); - if (ret < 0) - return ret; - - if (ret > ((long)image_end - (long)image)) - return -EFBIG; - jit_fill_hole(image, (unsigned int)(image_end - image)); ret = prepare_trampoline(&ctx, im, tlinks, func_addr, nregs, flags); diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c index 35747fafde57..58dc64dd94a8 100644 --- a/arch/riscv/net/bpf_jit_comp64.c +++ b/arch/riscv/net/bpf_jit_comp64.c @@ -1052,13 +1052,6 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, int ret; struct rv_jit_context ctx; - ret = arch_bpf_trampoline_size(im, m, flags, tlinks, func_addr); - if (ret < 0) - return ret; - - if (ret > (long)image_end - (long)image) - return -EFBIG; - ctx.ninsns = 0; /* * The bpf_int_jit_compile() uses a RW buffer (ctx.insns) to write the diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 2332ddeb396b..c1a06263a4f3 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1141,6 +1141,7 @@ enum bpf_tramp_prog_type { struct bpf_tramp_image { void *image; + int size; struct bpf_ksym ksym; struct percpu_ref pcref; void *ip_after_call; @@ -1325,7 +1326,7 @@ int arch_prepare_bpf_dispatcher(void *image, void *buf, s64 *funcs, int num_func void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from, struct bpf_prog *to); /* Called only from JIT-enabled code, so there's no need for stubs. */ -void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym); +void bpf_image_ksym_add(void *data, unsigned int size, struct bpf_ksym *ksym); void bpf_image_ksym_del(struct bpf_ksym *ksym); void bpf_ksym_add(struct bpf_ksym *ksym); void bpf_ksym_del(struct bpf_ksym *ksym); diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index e9e95879bce2..4d53c53fc5aa 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -355,6 +355,7 @@ int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks, void *image, void *image_end) { u32 flags; + int size; tlinks[BPF_TRAMP_FENTRY].links[0] = link; tlinks[BPF_TRAMP_FENTRY].nr_links = 1; @@ -362,6 +363,12 @@ int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks, * and it must be used alone. */ flags = model->ret_size > 0 ? BPF_TRAMP_F_RET_FENTRY_RET : 0; + + size = arch_bpf_trampoline_size(model, flags, tlinks, NULL); + if (size < 0) + return size; + if (size > (unsigned long)image_end - (unsigned long)image) + return -E2BIG; return arch_prepare_bpf_trampoline(NULL, image, image_end, model, flags, tlinks, NULL); } diff --git a/kernel/bpf/dispatcher.c b/kernel/bpf/dispatcher.c index 56760fc10e78..70fb82bf1637 100644 --- a/kernel/bpf/dispatcher.c +++ b/kernel/bpf/dispatcher.c @@ -154,7 +154,7 @@ void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from, d->image = NULL; goto out; } - bpf_image_ksym_add(d->image, &d->ksym); + bpf_image_ksym_add(d->image, PAGE_SIZE, &d->ksym); } prev_num_progs = d->num_progs; diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index b553cbd89e55..d382f5ebe06c 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -115,10 +115,10 @@ bool bpf_prog_has_trampoline(const struct bpf_prog *prog) (ptype == BPF_PROG_TYPE_LSM && eatype == BPF_LSM_MAC); } -void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym) +void bpf_image_ksym_add(void *data, unsigned int size, struct bpf_ksym *ksym) { ksym->start = (unsigned long) data; - ksym->end = ksym->start + PAGE_SIZE; + ksym->end = ksym->start + size; bpf_ksym_add(ksym); perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, PAGE_SIZE, false, ksym->name); @@ -254,8 +254,8 @@ bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total, bool *ip_a static void bpf_tramp_image_free(struct bpf_tramp_image *im) { bpf_image_ksym_del(&im->ksym); - arch_free_bpf_trampoline(im->image, PAGE_SIZE); - bpf_jit_uncharge_modmem(PAGE_SIZE); + arch_free_bpf_trampoline(im->image, im->size); + bpf_jit_uncharge_modmem(im->size); percpu_ref_exit(&im->pcref); kfree_rcu(im, rcu); } @@ -349,7 +349,7 @@ static void bpf_tramp_image_put(struct bpf_tramp_image *im) call_rcu_tasks_trace(&im->rcu, __bpf_tramp_image_put_rcu_tasks); } -static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key) +static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, int size) { struct bpf_tramp_image *im; struct bpf_ksym *ksym; @@ -360,12 +360,13 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key) if (!im) goto out; - err = bpf_jit_charge_modmem(PAGE_SIZE); + err = bpf_jit_charge_modmem(size); if (err) goto out_free_im; + im->size = size; err = -ENOMEM; - im->image = image = arch_alloc_bpf_trampoline(PAGE_SIZE); + im->image = image = arch_alloc_bpf_trampoline(size); if (!image) goto out_uncharge; @@ -376,13 +377,13 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key) ksym = &im->ksym; INIT_LIST_HEAD_RCU(&ksym->lnode); snprintf(ksym->name, KSYM_NAME_LEN, "bpf_trampoline_%llu", key); - bpf_image_ksym_add(image, ksym); + bpf_image_ksym_add(image, size, ksym); return im; out_free_image: - arch_free_bpf_trampoline(im->image, PAGE_SIZE); + arch_free_bpf_trampoline(im->image, im->size); out_uncharge: - bpf_jit_uncharge_modmem(PAGE_SIZE); + bpf_jit_uncharge_modmem(size); out_free_im: kfree(im); out: @@ -395,7 +396,7 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut struct bpf_tramp_links *tlinks; u32 orig_flags = tr->flags; bool ip_arg = false; - int err, total; + int err, total, size; tlinks = bpf_trampoline_get_progs(tr, &total, &ip_arg); if (IS_ERR(tlinks)) @@ -408,12 +409,6 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut goto out; } - im = bpf_tramp_image_alloc(tr->key); - if (IS_ERR(im)) { - err = PTR_ERR(im); - goto out; - } - /* clear all bits except SHARE_IPMODIFY and TAIL_CALL_CTX */ tr->flags &= (BPF_TRAMP_F_SHARE_IPMODIFY | BPF_TRAMP_F_TAIL_CALL_CTX); @@ -437,13 +432,31 @@ again: tr->flags |= BPF_TRAMP_F_ORIG_STACK; #endif - err = arch_prepare_bpf_trampoline(im, im->image, im->image + PAGE_SIZE, + size = arch_bpf_trampoline_size(&tr->func.model, tr->flags, + tlinks, tr->func.addr); + if (size < 0) { + err = size; + goto out; + } + + if (size > PAGE_SIZE) { + err = -E2BIG; + goto out; + } + + im = bpf_tramp_image_alloc(tr->key, size); + if (IS_ERR(im)) { + err = PTR_ERR(im); + goto out; + } + + err = arch_prepare_bpf_trampoline(im, im->image, im->image + size, &tr->func.model, tr->flags, tlinks, tr->func.addr); if (err < 0) goto out_free; - arch_protect_bpf_trampoline(im->image, PAGE_SIZE); + arch_protect_bpf_trampoline(im->image, im->size); WARN_ON(tr->cur_image && total == 0); if (tr->cur_image) @@ -463,8 +476,8 @@ again: tr->fops->func = NULL; tr->fops->trampoline = 0; - /* reset im->image memory attr for arch_prepare_bpf_trampoline */ - arch_unprotect_bpf_trampoline(im->image, PAGE_SIZE); + /* free im memory and reallocate later */ + bpf_tramp_image_free(im); goto again; } #endif -- cgit v1.2.3 From a833a17aeac73b33f79433d7cee68d5cafd71e4f Mon Sep 17 00:00:00 2001 From: Andrei Matei Date: Wed, 6 Dec 2023 23:11:48 -0500 Subject: bpf: Fix verification of indirect var-off stack access This patch fixes a bug around the verification of possibly-zero-sized stack accesses. When the access was done through a var-offset stack pointer, check_stack_access_within_bounds was incorrectly computing the maximum-offset of a zero-sized read to be the same as the register's min offset. Instead, we have to take in account the register's maximum possible value. The patch also simplifies how the max offset is checked; the check is now simpler than for min offset. The bug was allowing accesses to erroneously pass the check_stack_access_within_bounds() checks, only to later crash in check_stack_range_initialized() when all the possibly-affected stack slots are iterated (this time with a correct max offset). check_stack_range_initialized() is relying on check_stack_access_within_bounds() for its accesses to the stack-tracking vector to be within bounds; in the case of zero-sized accesses, we were essentially only verifying that the lowest possible slot was within bounds. We would crash when the max-offset of the stack pointer was >= 0 (which shouldn't pass verification, and hopefully is not something anyone's code attempts to do in practice). Thanks Hao for reporting! Fixes: 01f810ace9ed3 ("bpf: Allow variable-offset stack access") Reported-by: Hao Sun Signed-off-by: Andrei Matei Signed-off-by: Andrii Nakryiko Acked-by: Eduard Zingerman Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20231207041150.229139-2-andreimatei1@gmail.com Closes: https://lore.kernel.org/bpf/CACkBjsZGEUaRCHsmaX=h-efVogsRfK1FPxmkgb0Os_frnHiNdw@mail.gmail.com/ --- kernel/bpf/verifier.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 45e85fb76d82..85e4ab61084f 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6620,10 +6620,7 @@ static int check_stack_access_within_bounds( if (tnum_is_const(reg->var_off)) { min_off = reg->var_off.value + off; - if (access_size > 0) - max_off = min_off + access_size - 1; - else - max_off = min_off; + max_off = min_off + access_size; } else { if (reg->smax_value >= BPF_MAX_VAR_OFF || reg->smin_value <= -BPF_MAX_VAR_OFF) { @@ -6632,15 +6629,12 @@ static int check_stack_access_within_bounds( return -EACCES; } min_off = reg->smin_value + off; - if (access_size > 0) - max_off = reg->smax_value + off + access_size - 1; - else - max_off = min_off; + max_off = reg->smax_value + off + access_size; } err = check_stack_slot_within_bounds(min_off, state, type); - if (!err) - err = check_stack_slot_within_bounds(max_off, state, type); + if (!err && max_off > 0) + err = -EINVAL; /* out of stack access into non-negative offsets */ if (err) { if (tnum_is_const(reg->var_off)) { -- cgit v1.2.3 From 1d38a9ee81570c4bd61f557832dead4d6f816760 Mon Sep 17 00:00:00 2001 From: Andrei Matei Date: Wed, 6 Dec 2023 23:11:50 -0500 Subject: bpf: Guard stack limits against 32bit overflow This patch promotes the arithmetic around checking stack bounds to be done in the 64-bit domain, instead of the current 32bit. The arithmetic implies adding together a 64-bit register with a int offset. The register was checked to be below 1<<29 when it was variable, but not when it was fixed. The offset either comes from an instruction (in which case it is 16 bit), from another register (in which case the caller checked it to be below 1<<29 [1]), or from the size of an argument to a kfunc (in which case it can be a u32 [2]). Between the register being inconsistently checked to be below 1<<29, and the offset being up to an u32, it appears that we were open to overflowing the `int`s which were currently used for arithmetic. [1] https://github.com/torvalds/linux/blob/815fb87b753055df2d9e50f6cd80eb10235fe3e9/kernel/bpf/verifier.c#L7494-L7498 [2] https://github.com/torvalds/linux/blob/815fb87b753055df2d9e50f6cd80eb10235fe3e9/kernel/bpf/verifier.c#L11904 Reported-by: Andrii Nakryiko Signed-off-by: Andrei Matei Signed-off-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20231207041150.229139-4-andreimatei1@gmail.com --- kernel/bpf/verifier.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 85e4ab61084f..0e77bb52542d 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6577,7 +6577,7 @@ static int check_ptr_to_map_access(struct bpf_verifier_env *env, * The minimum valid offset is -MAX_BPF_STACK for writes, and * -state->allocated_stack for reads. */ -static int check_stack_slot_within_bounds(int off, +static int check_stack_slot_within_bounds(s64 off, struct bpf_func_state *state, enum bpf_access_type t) { @@ -6606,7 +6606,7 @@ static int check_stack_access_within_bounds( struct bpf_reg_state *regs = cur_regs(env); struct bpf_reg_state *reg = regs + regno; struct bpf_func_state *state = func(env, reg); - int min_off, max_off; + s64 min_off, max_off; int err; char *err_extra; @@ -6619,7 +6619,7 @@ static int check_stack_access_within_bounds( err_extra = " write to"; if (tnum_is_const(reg->var_off)) { - min_off = reg->var_off.value + off; + min_off = (s64)reg->var_off.value + off; max_off = min_off + access_size; } else { if (reg->smax_value >= BPF_MAX_VAR_OFF || -- cgit v1.2.3 From 6b4a64bafd107e521c01eec3453ce94a3fb38529 Mon Sep 17 00:00:00 2001 From: Andrei Matei Date: Thu, 7 Dec 2023 22:25:18 -0500 Subject: bpf: Fix accesses to uninit stack slots Privileged programs are supposed to be able to read uninitialized stack memory (ever since 6715df8d5) but, before this patch, these accesses were permitted inconsistently. In particular, accesses were permitted above state->allocated_stack, but not below it. In other words, if the stack was already "large enough", the access was permitted, but otherwise the access was rejected instead of being allowed to "grow the stack". This undesired rejection was happening in two places: - in check_stack_slot_within_bounds() - in check_stack_range_initialized() This patch arranges for these accesses to be permitted. A bunch of tests that were relying on the old rejection had to change; all of them were changed to add also run unprivileged, in which case the old behavior persists. One tests couldn't be updated - global_func16 - because it can't run unprivileged for other reasons. This patch also fixes the tracking of the stack size for variable-offset reads. This second fix is bundled in the same commit as the first one because they're inter-related. Before this patch, writes to the stack using registers containing a variable offset (as opposed to registers with fixed, known values) were not properly contributing to the function's needed stack size. As a result, it was possible for a program to verify, but then to attempt to read out-of-bounds data at runtime because a too small stack had been allocated for it. Each function tracks the size of the stack it needs in bpf_subprog_info.stack_depth, which is maintained by update_stack_depth(). For regular memory accesses, check_mem_access() was calling update_state_depth() but it was passing in only the fixed part of the offset register, ignoring the variable offset. This was incorrect; the minimum possible value of that register should be used instead. This tracking is now fixed by centralizing the tracking of stack size in grow_stack_state(), and by lifting the calls to grow_stack_state() to check_stack_access_within_bounds() as suggested by Andrii. The code is now simpler and more convincingly tracks the correct maximum stack size. check_stack_range_initialized() can now rely on enough stack having been allocated for the access; this helps with the fix for the first issue. A few tests were changed to also check the stack depth computation. The one that fails without this patch is verifier_var_off:stack_write_priv_vs_unpriv. Fixes: 01f810ace9ed3 ("bpf: Allow variable-offset stack access") Reported-by: Hao Sun Signed-off-by: Andrei Matei Signed-off-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20231208032519.260451-3-andreimatei1@gmail.com Closes: https://lore.kernel.org/bpf/CABWLsev9g8UP_c3a=1qbuZUi20tGoUXoU07FPf-5FLvhOKOY+Q@mail.gmail.com/ --- kernel/bpf/verifier.c | 65 +++++++++------------- tools/testing/selftests/bpf/progs/iters.c | 2 +- .../selftests/bpf/progs/test_global_func16.c | 2 +- .../selftests/bpf/progs/verifier_basic_stack.c | 8 +-- .../testing/selftests/bpf/progs/verifier_int_ptr.c | 5 +- .../selftests/bpf/progs/verifier_raw_stack.c | 5 +- .../testing/selftests/bpf/progs/verifier_var_off.c | 62 +++++++++++++++++---- .../selftests/bpf/verifier/atomic_cmpxchg.c | 11 ---- tools/testing/selftests/bpf/verifier/calls.c | 4 +- 9 files changed, 92 insertions(+), 72 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 0e77bb52542d..de1e29fa467e 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1259,7 +1259,10 @@ static int resize_reference_state(struct bpf_func_state *state, size_t n) return 0; } -static int grow_stack_state(struct bpf_func_state *state, int size) +/* Possibly update state->allocated_stack to be at least size bytes. Also + * possibly update the function's high-water mark in its bpf_subprog_info. + */ +static int grow_stack_state(struct bpf_verifier_env *env, struct bpf_func_state *state, int size) { size_t old_n = state->allocated_stack / BPF_REG_SIZE, n = size / BPF_REG_SIZE; @@ -1271,6 +1274,11 @@ static int grow_stack_state(struct bpf_func_state *state, int size) return -ENOMEM; state->allocated_stack = size; + + /* update known max for given subprogram */ + if (env->subprog_info[state->subprogno].stack_depth < size) + env->subprog_info[state->subprogno].stack_depth = size; + return 0; } @@ -4440,9 +4448,6 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, struct bpf_reg_state *reg = NULL; int insn_flags = insn_stack_access_flags(state->frameno, spi); - err = grow_stack_state(state, round_up(slot + 1, BPF_REG_SIZE)); - if (err) - return err; /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0, * so it's aligned access and [off, off + size) are within stack limits */ @@ -4595,10 +4600,6 @@ static int check_stack_write_var_off(struct bpf_verifier_env *env, (!value_reg && is_bpf_st_mem(insn) && insn->imm == 0)) writing_zero = true; - err = grow_stack_state(state, round_up(-min_off, BPF_REG_SIZE)); - if (err) - return err; - for (i = min_off; i < max_off; i++) { int spi; @@ -5774,20 +5775,6 @@ static int check_ptr_alignment(struct bpf_verifier_env *env, strict); } -static int update_stack_depth(struct bpf_verifier_env *env, - const struct bpf_func_state *func, - int off) -{ - u16 stack = env->subprog_info[func->subprogno].stack_depth; - - if (stack >= -off) - return 0; - - /* update known max for given subprogram */ - env->subprog_info[func->subprogno].stack_depth = -off; - return 0; -} - /* starting from main bpf function walk all instructions of the function * and recursively walk all callees that given function can call. * Ignore jump and exit insns. @@ -6577,13 +6564,14 @@ static int check_ptr_to_map_access(struct bpf_verifier_env *env, * The minimum valid offset is -MAX_BPF_STACK for writes, and * -state->allocated_stack for reads. */ -static int check_stack_slot_within_bounds(s64 off, - struct bpf_func_state *state, - enum bpf_access_type t) +static int check_stack_slot_within_bounds(struct bpf_verifier_env *env, + s64 off, + struct bpf_func_state *state, + enum bpf_access_type t) { int min_valid_off; - if (t == BPF_WRITE) + if (t == BPF_WRITE || env->allow_uninit_stack) min_valid_off = -MAX_BPF_STACK; else min_valid_off = -state->allocated_stack; @@ -6632,7 +6620,7 @@ static int check_stack_access_within_bounds( max_off = reg->smax_value + off + access_size; } - err = check_stack_slot_within_bounds(min_off, state, type); + err = check_stack_slot_within_bounds(env, min_off, state, type); if (!err && max_off > 0) err = -EINVAL; /* out of stack access into non-negative offsets */ @@ -6647,8 +6635,10 @@ static int check_stack_access_within_bounds( verbose(env, "invalid variable-offset%s stack R%d var_off=%s off=%d size=%d\n", err_extra, regno, tn_buf, off, access_size); } + return err; } - return err; + + return grow_stack_state(env, state, round_up(-min_off, BPF_REG_SIZE)); } /* check whether memory at (regno + off) is accessible for t = (read | write) @@ -6663,7 +6653,6 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn { struct bpf_reg_state *regs = cur_regs(env); struct bpf_reg_state *reg = regs + regno; - struct bpf_func_state *state; int size, err = 0; size = bpf_size_to_bytes(bpf_size); @@ -6806,11 +6795,6 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn if (err) return err; - state = func(env, reg); - err = update_stack_depth(env, state, off); - if (err) - return err; - if (t == BPF_READ) err = check_stack_read(env, regno, off, size, value_regno); @@ -7004,7 +6988,8 @@ static int check_atomic(struct bpf_verifier_env *env, int insn_idx, struct bpf_i /* When register 'regno' is used to read the stack (either directly or through * a helper function) make sure that it's within stack boundary and, depending - * on the access type, that all elements of the stack are initialized. + * on the access type and privileges, that all elements of the stack are + * initialized. * * 'off' includes 'regno->off', but not its dynamic part (if any). * @@ -7112,8 +7097,11 @@ static int check_stack_range_initialized( slot = -i - 1; spi = slot / BPF_REG_SIZE; - if (state->allocated_stack <= slot) - goto err; + if (state->allocated_stack <= slot) { + verbose(env, "verifier bug: allocated_stack too small"); + return -EFAULT; + } + stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE]; if (*stype == STACK_MISC) goto mark; @@ -7137,7 +7125,6 @@ static int check_stack_range_initialized( goto mark; } -err: if (tnum_is_const(reg->var_off)) { verbose(env, "invalid%s read from stack R%d off %d+%d size %d\n", err_extra, regno, min_off, i - min_off, access_size); @@ -7162,7 +7149,7 @@ mark: * helper may write to the entire memory range. */ } - return update_stack_depth(env, state, min_off); + return 0; } static int check_helper_mem_access(struct bpf_verifier_env *env, int regno, diff --git a/tools/testing/selftests/bpf/progs/iters.c b/tools/testing/selftests/bpf/progs/iters.c index b2181f850d3e..3aca3dc145b5 100644 --- a/tools/testing/selftests/bpf/progs/iters.c +++ b/tools/testing/selftests/bpf/progs/iters.c @@ -846,7 +846,7 @@ __naked int delayed_precision_mark(void) "call %[bpf_iter_num_next];" "if r0 == 0 goto 2f;" "if r6 != 42 goto 3f;" - "r7 = -32;" + "r7 = -33;" "call %[bpf_get_prandom_u32];" "r6 = r0;" "goto 1b;\n" diff --git a/tools/testing/selftests/bpf/progs/test_global_func16.c b/tools/testing/selftests/bpf/progs/test_global_func16.c index e7206304632e..e3e64bc472cd 100644 --- a/tools/testing/selftests/bpf/progs/test_global_func16.c +++ b/tools/testing/selftests/bpf/progs/test_global_func16.c @@ -13,7 +13,7 @@ __noinline int foo(int (*arr)[10]) } SEC("cgroup_skb/ingress") -__failure __msg("invalid indirect read from stack") +__success int global_func16(struct __sk_buff *skb) { int array[10]; diff --git a/tools/testing/selftests/bpf/progs/verifier_basic_stack.c b/tools/testing/selftests/bpf/progs/verifier_basic_stack.c index 359df865a8f3..8d77cc5323d3 100644 --- a/tools/testing/selftests/bpf/progs/verifier_basic_stack.c +++ b/tools/testing/selftests/bpf/progs/verifier_basic_stack.c @@ -27,8 +27,8 @@ __naked void stack_out_of_bounds(void) SEC("socket") __description("uninitialized stack1") -__failure __msg("invalid indirect read from stack") -__failure_unpriv +__success __log_level(4) __msg("stack depth 8") +__failure_unpriv __msg_unpriv("invalid indirect read from stack") __naked void uninitialized_stack1(void) { asm volatile (" \ @@ -45,8 +45,8 @@ __naked void uninitialized_stack1(void) SEC("socket") __description("uninitialized stack2") -__failure __msg("invalid read from stack") -__failure_unpriv +__success __log_level(4) __msg("stack depth 8") +__failure_unpriv __msg_unpriv("invalid read from stack") __naked void uninitialized_stack2(void) { asm volatile (" \ diff --git a/tools/testing/selftests/bpf/progs/verifier_int_ptr.c b/tools/testing/selftests/bpf/progs/verifier_int_ptr.c index 74d9cad469d9..9fc3fae5cd83 100644 --- a/tools/testing/selftests/bpf/progs/verifier_int_ptr.c +++ b/tools/testing/selftests/bpf/progs/verifier_int_ptr.c @@ -5,9 +5,10 @@ #include #include "bpf_misc.h" -SEC("cgroup/sysctl") +SEC("socket") __description("ARG_PTR_TO_LONG uninitialized") -__failure __msg("invalid indirect read from stack R4 off -16+0 size 8") +__success +__failure_unpriv __msg_unpriv("invalid indirect read from stack R4 off -16+0 size 8") __naked void arg_ptr_to_long_uninitialized(void) { asm volatile (" \ diff --git a/tools/testing/selftests/bpf/progs/verifier_raw_stack.c b/tools/testing/selftests/bpf/progs/verifier_raw_stack.c index efbfc3a4ad6a..f67390224a9c 100644 --- a/tools/testing/selftests/bpf/progs/verifier_raw_stack.c +++ b/tools/testing/selftests/bpf/progs/verifier_raw_stack.c @@ -5,9 +5,10 @@ #include #include "bpf_misc.h" -SEC("tc") +SEC("socket") __description("raw_stack: no skb_load_bytes") -__failure __msg("invalid read from stack R6 off=-8 size=8") +__success +__failure_unpriv __msg_unpriv("invalid read from stack R6 off=-8 size=8") __naked void stack_no_skb_load_bytes(void) { asm volatile (" \ diff --git a/tools/testing/selftests/bpf/progs/verifier_var_off.c b/tools/testing/selftests/bpf/progs/verifier_var_off.c index b7bdd7db3a35..c810f4f6f479 100644 --- a/tools/testing/selftests/bpf/progs/verifier_var_off.c +++ b/tools/testing/selftests/bpf/progs/verifier_var_off.c @@ -59,9 +59,10 @@ __naked void stack_read_priv_vs_unpriv(void) " ::: __clobber_all); } -SEC("lwt_in") +SEC("cgroup/skb") __description("variable-offset stack read, uninitialized") -__failure __msg("invalid variable-offset read from stack R2") +__success +__failure_unpriv __msg_unpriv("R2 variable stack access prohibited for !root") __naked void variable_offset_stack_read_uninitialized(void) { asm volatile (" \ @@ -83,12 +84,55 @@ __naked void variable_offset_stack_read_uninitialized(void) SEC("socket") __description("variable-offset stack write, priv vs unpriv") -__success __failure_unpriv +__success +/* Check that the maximum stack depth is correctly maintained according to the + * maximum possible variable offset. + */ +__log_level(4) __msg("stack depth 16") +__failure_unpriv /* Variable stack access is rejected for unprivileged. */ __msg_unpriv("R2 variable stack access prohibited for !root") __retval(0) __naked void stack_write_priv_vs_unpriv(void) +{ + asm volatile (" \ + /* Get an unknown value */ \ + r2 = *(u32*)(r1 + 0); \ + /* Make it small and 8-byte aligned */ \ + r2 &= 8; \ + r2 -= 16; \ + /* Add it to fp. We now have either fp-8 or \ + * fp-16, but we don't know which \ + */ \ + r2 += r10; \ + /* Dereference it for a stack write */ \ + r0 = 0; \ + *(u64*)(r2 + 0) = r0; \ + exit; \ +" ::: __clobber_all); +} + +/* Similar to the previous test, but this time also perform a read from the + * address written to with a variable offset. The read is allowed, showing that, + * after a variable-offset write, a priviledged program can read the slots that + * were in the range of that write (even if the verifier doesn't actually know if + * the slot being read was really written to or not. + * + * Despite this test being mostly a superset, the previous test is also kept for + * the sake of it checking the stack depth in the case where there is no read. + */ +SEC("socket") +__description("variable-offset stack write followed by read") +__success +/* Check that the maximum stack depth is correctly maintained according to the + * maximum possible variable offset. + */ +__log_level(4) __msg("stack depth 16") +__failure_unpriv +__msg_unpriv("R2 variable stack access prohibited for !root") +__retval(0) +__naked void stack_write_followed_by_read(void) { asm volatile (" \ /* Get an unknown value */ \ @@ -103,12 +147,7 @@ __naked void stack_write_priv_vs_unpriv(void) /* Dereference it for a stack write */ \ r0 = 0; \ *(u64*)(r2 + 0) = r0; \ - /* Now read from the address we just wrote. This shows\ - * that, after a variable-offset write, a priviledged\ - * program can read the slots that were in the range of\ - * that write (even if the verifier doesn't actually know\ - * if the slot being read was really written to or not.\ - */ \ + /* Now read from the address we just wrote. */ \ r3 = *(u64*)(r2 + 0); \ r0 = 0; \ exit; \ @@ -282,9 +321,10 @@ __naked void access_min_out_of_bound(void) : __clobber_all); } -SEC("lwt_in") +SEC("cgroup/skb") __description("indirect variable-offset stack access, min_off < min_initialized") -__failure __msg("invalid indirect read from stack R2 var_off") +__success +__failure_unpriv __msg_unpriv("R2 variable stack access prohibited for !root") __naked void access_min_off_min_initialized(void) { asm volatile (" \ diff --git a/tools/testing/selftests/bpf/verifier/atomic_cmpxchg.c b/tools/testing/selftests/bpf/verifier/atomic_cmpxchg.c index 319337bdcfc8..9a7b1106fda8 100644 --- a/tools/testing/selftests/bpf/verifier/atomic_cmpxchg.c +++ b/tools/testing/selftests/bpf/verifier/atomic_cmpxchg.c @@ -83,17 +83,6 @@ .result = REJECT, .errstr = "!read_ok", }, -{ - "Can't use cmpxchg on uninit memory", - .insns = { - BPF_MOV64_IMM(BPF_REG_0, 3), - BPF_MOV64_IMM(BPF_REG_2, 4), - BPF_ATOMIC_OP(BPF_DW, BPF_CMPXCHG, BPF_REG_10, BPF_REG_2, -8), - BPF_EXIT_INSN(), - }, - .result = REJECT, - .errstr = "invalid read from stack", -}, { "BPF_W cmpxchg should zero top 32 bits", .insns = { diff --git a/tools/testing/selftests/bpf/verifier/calls.c b/tools/testing/selftests/bpf/verifier/calls.c index 3d5cd51071f0..ab25a81fd3a1 100644 --- a/tools/testing/selftests/bpf/verifier/calls.c +++ b/tools/testing/selftests/bpf/verifier/calls.c @@ -1505,7 +1505,9 @@ .prog_type = BPF_PROG_TYPE_XDP, .fixup_map_hash_8b = { 23 }, .result = REJECT, - .errstr = "invalid read from stack R7 off=-16 size=8", + .errstr = "R0 invalid mem access 'scalar'", + .result_unpriv = REJECT, + .errstr_unpriv = "invalid read from stack R7 off=-16 size=8", }, { "calls: two calls that receive map_value via arg=ptr_stack_of_caller. test1", -- cgit v1.2.3 From 2929bfac006d8f8e22b307d04e0d71bcb84db698 Mon Sep 17 00:00:00 2001 From: Andrei Matei Date: Thu, 7 Dec 2023 22:25:19 -0500 Subject: bpf: Minor cleanup around stack bounds Push the rounding up of stack offsets into the function responsible for growing the stack, rather than relying on all the callers to do it. Uncertainty about whether the callers did it or not tripped up people in a previous review. Signed-off-by: Andrei Matei Signed-off-by: Andrii Nakryiko Acked-by: Eduard Zingerman Link: https://lore.kernel.org/bpf/20231208032519.260451-4-andreimatei1@gmail.com --- kernel/bpf/verifier.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index de1e29fa467e..fb690539d5f6 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1264,7 +1264,11 @@ static int resize_reference_state(struct bpf_func_state *state, size_t n) */ static int grow_stack_state(struct bpf_verifier_env *env, struct bpf_func_state *state, int size) { - size_t old_n = state->allocated_stack / BPF_REG_SIZE, n = size / BPF_REG_SIZE; + size_t old_n = state->allocated_stack / BPF_REG_SIZE, n; + + /* The stack size is always a multiple of BPF_REG_SIZE. */ + size = round_up(size, BPF_REG_SIZE); + n = size / BPF_REG_SIZE; if (old_n >= n) return 0; @@ -6638,7 +6642,10 @@ static int check_stack_access_within_bounds( return err; } - return grow_stack_state(env, state, round_up(-min_off, BPF_REG_SIZE)); + /* Note that there is no stack access with offset zero, so the needed stack + * size is -min_off, not -min_off+1. + */ + return grow_stack_state(env, state, -min_off /* size */); } /* check whether memory at (regno + off) is accessible for t = (read | write) -- cgit v1.2.3 From 73d9eb340d2b95e0e86a656a7f3157c137f10129 Mon Sep 17 00:00:00 2001 From: Yafang Shao Date: Wed, 6 Dec 2023 11:53:24 +0000 Subject: bpf: Enable bpf_cgrp_storage for cgroup1 non-attach case In the current cgroup1 environment, associating operations between cgroups and applications in a BPF program requires storing a mapping of cgroup_id to application either in a hash map or maintaining it in userspace. However, by enabling bpf_cgrp_storage for cgroup1, it becomes possible to conveniently store application-specific information in cgroup-local storage and utilize it within BPF programs. Furthermore, enabling this feature for cgroup1 involves minor modifications for the non-attach case, streamlining the process. However, when it comes to enabling this functionality for the cgroup1 attach case, it presents challenges. Therefore, the decision is to focus on enabling it solely for the cgroup1 non-attach case at present. If attempting to attach to a cgroup1 fd, the operation will simply fail with the error code -EBADF. Signed-off-by: Yafang Shao Acked-by: Tejun Heo Acked-by: Yonghong Song Link: https://lore.kernel.org/r/20231206115326.4295-2-laoar.shao@gmail.com Signed-off-by: Martin KaFai Lau --- kernel/bpf/bpf_cgrp_storage.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/bpf_cgrp_storage.c b/kernel/bpf/bpf_cgrp_storage.c index d44fe8dd9732..28efd0a3f220 100644 --- a/kernel/bpf/bpf_cgrp_storage.c +++ b/kernel/bpf/bpf_cgrp_storage.c @@ -82,7 +82,7 @@ static void *bpf_cgrp_storage_lookup_elem(struct bpf_map *map, void *key) int fd; fd = *(int *)key; - cgroup = cgroup_get_from_fd(fd); + cgroup = cgroup_v1v2_get_from_fd(fd); if (IS_ERR(cgroup)) return ERR_CAST(cgroup); @@ -101,7 +101,7 @@ static long bpf_cgrp_storage_update_elem(struct bpf_map *map, void *key, int fd; fd = *(int *)key; - cgroup = cgroup_get_from_fd(fd); + cgroup = cgroup_v1v2_get_from_fd(fd); if (IS_ERR(cgroup)) return PTR_ERR(cgroup); @@ -131,7 +131,7 @@ static long bpf_cgrp_storage_delete_elem(struct bpf_map *map, void *key) int err, fd; fd = *(int *)key; - cgroup = cgroup_get_from_fd(fd); + cgroup = cgroup_v1v2_get_from_fd(fd); if (IS_ERR(cgroup)) return PTR_ERR(cgroup); -- cgit v1.2.3 From c26f2a8901393c9f81909da0a4324587092bd3a3 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Fri, 8 Dec 2023 18:23:49 +0800 Subject: bpf: Remove unnecessary wait from bpf_map_copy_value() Both map_lookup_elem() and generic_map_lookup_batch() use bpf_map_copy_value() to lookup and copy the value, and there is no update operation in bpf_map_copy_value(), so just remove the invocation of maybe_wait_bpf_programs() from it. Fixes: 15c14a3dca42 ("bpf: Add bpf_map_{value_size, update_value, map_copy_value} functions") Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20231208102355.2628918-2-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/syscall.c | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index aff045eed375..9ad3f527ab37 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -264,7 +264,6 @@ static int bpf_map_copy_value(struct bpf_map *map, void *key, void *value, } bpf_enable_instrumentation(); - maybe_wait_bpf_programs(map); return err; } -- cgit v1.2.3 From 37ba5b59d6adfa08926acd3a833608487a18c2ef Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Fri, 8 Dec 2023 18:23:50 +0800 Subject: bpf: Call maybe_wait_bpf_programs() only once for generic_map_update_batch() Just like commit 9087c6ff8dfe ("bpf: Call maybe_wait_bpf_programs() only once from generic_map_delete_batch()"), there is also no need to call maybe_wait_bpf_programs() for each update in batched update, so only call it once in generic_map_update_batch(). Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20231208102355.2628918-3-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/syscall.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 9ad3f527ab37..07e671431987 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -203,7 +203,6 @@ static int bpf_map_update_value(struct bpf_map *map, struct file *map_file, rcu_read_unlock(); } bpf_enable_instrumentation(); - maybe_wait_bpf_programs(map); return err; } @@ -1577,6 +1576,7 @@ static int map_update_elem(union bpf_attr *attr, bpfptr_t uattr) } err = bpf_map_update_value(map, f.file, key, value, attr->flags); + maybe_wait_bpf_programs(map); kvfree(value); free_key: @@ -1816,6 +1816,8 @@ int generic_map_update_batch(struct bpf_map *map, struct file *map_file, kvfree(value); kvfree(key); + + maybe_wait_bpf_programs(map); return err; } -- cgit v1.2.3 From 012772581d040607ac1f981f47f6afd2336b4580 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Fri, 8 Dec 2023 18:23:51 +0800 Subject: bpf: Add missed maybe_wait_bpf_programs() for htab of maps When doing batched lookup and deletion operations on htab of maps, maybe_wait_bpf_programs() is needed to ensure all programs don't use the inner map after the bpf syscall returns. Instead of adding the wait in __htab_map_lookup_and_delete_batch(), adding the wait in bpf_map_do_batch() and also removing the calling of maybe_wait_bpf_programs() from generic_map_{delete,update}_batch(). Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20231208102355.2628918-4-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/syscall.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 07e671431987..2e6ef361da1c 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1758,7 +1758,6 @@ int generic_map_delete_batch(struct bpf_map *map, kvfree(key); - maybe_wait_bpf_programs(map); return err; } @@ -1817,7 +1816,6 @@ int generic_map_update_batch(struct bpf_map *map, struct file *map_file, kvfree(value); kvfree(key); - maybe_wait_bpf_programs(map); return err; } @@ -5031,8 +5029,10 @@ static int bpf_map_do_batch(const union bpf_attr *attr, else BPF_DO_BATCH(map->ops->map_delete_batch, map, attr, uattr); err_put: - if (has_write) + if (has_write) { + maybe_wait_bpf_programs(map); bpf_map_write_active_dec(map); + } fdput(f); return err; } -- cgit v1.2.3 From 67ad2c73ff29b32bd09135ec07c26e59490dbb3b Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Fri, 8 Dec 2023 18:23:52 +0800 Subject: bpf: Only call maybe_wait_bpf_programs() when map operation succeeds There is no need to call maybe_wait_bpf_programs() if update or deletion operation fails. So only call maybe_wait_bpf_programs() if update or deletion operation succeeds. Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20231208102355.2628918-5-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/syscall.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 2e6ef361da1c..dd641475b65f 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1576,7 +1576,8 @@ static int map_update_elem(union bpf_attr *attr, bpfptr_t uattr) } err = bpf_map_update_value(map, f.file, key, value, attr->flags); - maybe_wait_bpf_programs(map); + if (!err) + maybe_wait_bpf_programs(map); kvfree(value); free_key: @@ -1632,7 +1633,8 @@ static int map_delete_elem(union bpf_attr *attr, bpfptr_t uattr) err = map->ops->map_delete_elem(map, key); rcu_read_unlock(); bpf_enable_instrumentation(); - maybe_wait_bpf_programs(map); + if (!err) + maybe_wait_bpf_programs(map); out: kvfree(key); err_put: -- cgit v1.2.3 From 06e5c999f10269a532304e89a6adb2fbfeb0593c Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Fri, 8 Dec 2023 18:23:53 +0800 Subject: bpf: Set uattr->batch.count as zero before batched update or deletion generic_map_{delete,update}_batch() doesn't set uattr->batch.count as zero before it tries to allocate memory for key. If the memory allocation fails, the value of uattr->batch.count will be incorrect. Fix it by setting uattr->batch.count as zero beore batched update or deletion. Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20231208102355.2628918-6-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/syscall.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index dd641475b65f..06320d9abf33 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1731,6 +1731,9 @@ int generic_map_delete_batch(struct bpf_map *map, if (!max_count) return 0; + if (put_user(0, &uattr->batch.count)) + return -EFAULT; + key = kvmalloc(map->key_size, GFP_USER | __GFP_NOWARN); if (!key) return -ENOMEM; @@ -1787,6 +1790,9 @@ int generic_map_update_batch(struct bpf_map *map, struct file *map_file, if (!max_count) return 0; + if (put_user(0, &uattr->batch.count)) + return -EFAULT; + key = kvmalloc(map->key_size, GFP_USER | __GFP_NOWARN); if (!key) return -ENOMEM; -- cgit v1.2.3 From 482d548d40b0af9af730e4869903d4433e44f014 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Fri, 8 Dec 2023 17:09:57 -0800 Subject: bpf: handle fake register spill to stack with BPF_ST_MEM instruction When verifier validates BPF_ST_MEM instruction that stores known constant to stack (e.g., *(u64 *)(r10 - 8) = 123), it effectively spills a fake register with a constant (but initially imprecise) value to a stack slot. Because read-side logic treats it as a proper register fill from stack slot, we need to mark such stack slot initialization as INSN_F_STACK_ACCESS instruction to stop precision backtracking from missing it. Fixes: 41f6f64e6999 ("bpf: support non-r10 register spill/fill to/from stack in precision tracking") Signed-off-by: Andrii Nakryiko Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20231209010958.66758-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index fb690539d5f6..727a59e4a647 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4498,7 +4498,6 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, __mark_reg_known(&fake_reg, insn->imm); fake_reg.type = SCALAR_VALUE; save_register_state(env, state, spi, &fake_reg, size); - insn_flags = 0; /* not a register spill */ } else if (reg && is_spillable_regtype(reg->type)) { /* register containing pointer is being spilled into stack */ if (size != BPF_REG_SIZE) { -- cgit v1.2.3 From a6de18f310a511278c1ff16b96eb2d500eada725 Mon Sep 17 00:00:00 2001 From: David Vernet Date: Thu, 7 Dec 2023 15:08:42 -0600 Subject: bpf: Add bpf_cpumask_weight() kfunc It can be useful to query how many bits are set in a cpumask. For example, if you want to perform special logic for the last remaining core that's set in a mask. Let's therefore add a new bpf_cpumask_weight() kfunc which checks how many bits are set in a mask. Signed-off-by: David Vernet Acked-by: Yonghong Song Link: https://lore.kernel.org/r/20231207210843.168466-2-void@manifault.com Signed-off-by: Alexei Starovoitov --- Documentation/bpf/cpumasks.rst | 2 +- kernel/bpf/cpumask.c | 12 ++++++++++++ 2 files changed, 13 insertions(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/Documentation/bpf/cpumasks.rst b/Documentation/bpf/cpumasks.rst index a22b6ad105fb..b5d47a04da5d 100644 --- a/Documentation/bpf/cpumasks.rst +++ b/Documentation/bpf/cpumasks.rst @@ -352,7 +352,7 @@ can be used to query the contents of cpumasks. .. kernel-doc:: kernel/bpf/cpumask.c :identifiers: bpf_cpumask_first bpf_cpumask_first_zero bpf_cpumask_first_and - bpf_cpumask_test_cpu + bpf_cpumask_test_cpu bpf_cpumask_weight .. kernel-doc:: kernel/bpf/cpumask.c :identifiers: bpf_cpumask_equal bpf_cpumask_intersects bpf_cpumask_subset diff --git a/kernel/bpf/cpumask.c b/kernel/bpf/cpumask.c index e01c741e54e7..7499b7d8c06f 100644 --- a/kernel/bpf/cpumask.c +++ b/kernel/bpf/cpumask.c @@ -405,6 +405,17 @@ __bpf_kfunc u32 bpf_cpumask_any_and_distribute(const struct cpumask *src1, return cpumask_any_and_distribute(src1, src2); } +/** + * bpf_cpumask_weight() - Return the number of bits in @cpumask. + * @cpumask: The cpumask being queried. + * + * Count the number of set bits in the given cpumask. + */ +__bpf_kfunc u32 bpf_cpumask_weight(const struct cpumask *cpumask) +{ + return cpumask_weight(cpumask); +} + __bpf_kfunc_end_defs(); BTF_SET8_START(cpumask_kfunc_btf_ids) @@ -432,6 +443,7 @@ BTF_ID_FLAGS(func, bpf_cpumask_full, KF_RCU) BTF_ID_FLAGS(func, bpf_cpumask_copy, KF_RCU) BTF_ID_FLAGS(func, bpf_cpumask_any_distribute, KF_RCU) BTF_ID_FLAGS(func, bpf_cpumask_any_and_distribute, KF_RCU) +BTF_ID_FLAGS(func, bpf_cpumask_weight, KF_RCU) BTF_SET8_END(cpumask_kfunc_btf_ids) static const struct btf_kfunc_id_set cpumask_kfunc_set = { -- cgit v1.2.3 From 1e68485d8299860e68c4e1d29589ff0d20db0287 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 4 Dec 2023 15:39:19 -0800 Subject: bpf: log PTR_TO_MEM memory size in verifier log Emit valid memory size addressable through PTR_TO_MEM register. Signed-off-by: Andrii Nakryiko Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20231204233931.49758-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/log.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c index 55d019f30e91..61d7d23a0118 100644 --- a/kernel/bpf/log.c +++ b/kernel/bpf/log.c @@ -682,6 +682,10 @@ static void print_reg_state(struct bpf_verifier_env *env, verbose_a("r="); verbose_unum(env, reg->range); } + if (base_type(t) == PTR_TO_MEM) { + verbose_a("sz="); + verbose_unum(env, reg->mem_size); + } if (tnum_is_const(reg->var_off)) { /* a pointer register with fixed offset */ if (reg->var_off.value) { -- cgit v1.2.3 From 22b769bb4f87060774bfdd6facbab438ed3b8453 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 4 Dec 2023 15:39:20 -0800 Subject: bpf: emit more dynptr information in verifier log Emit dynptr type for CONST_PTR_TO_DYNPTR register. Also emit id, ref_obj_id, and dynptr_id fields for STACK_DYNPTR stack slots. Signed-off-by: Andrii Nakryiko Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20231204233931.49758-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/log.c | 25 ++++++++++++++++--------- 1 file changed, 16 insertions(+), 9 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c index 61d7d23a0118..594a234f122b 100644 --- a/kernel/bpf/log.c +++ b/kernel/bpf/log.c @@ -628,6 +628,12 @@ static bool type_is_map_ptr(enum bpf_reg_type t) { } } +/* + * _a stands for append, was shortened to avoid multiline statements below. + * This macro is used to output a comma separated list of attributes. + */ +#define verbose_a(fmt, ...) ({ verbose(env, "%s" fmt, sep, ##__VA_ARGS__); sep = ","; }) + static void print_reg_state(struct bpf_verifier_env *env, const struct bpf_func_state *state, const struct bpf_reg_state *reg) @@ -643,11 +649,6 @@ static void print_reg_state(struct bpf_verifier_env *env, verbose_snum(env, reg->var_off.value + reg->off); return; } -/* - * _a stands for append, was shortened to avoid multiline statements below. - * This macro is used to output a comma separated list of attributes. - */ -#define verbose_a(fmt, ...) ({ verbose(env, "%s" fmt, sep, ##__VA_ARGS__); sep = ","; }) verbose(env, "%s", reg_type_str(env, t)); if (t == PTR_TO_STACK) { @@ -686,6 +687,8 @@ static void print_reg_state(struct bpf_verifier_env *env, verbose_a("sz="); verbose_unum(env, reg->mem_size); } + if (t == CONST_PTR_TO_DYNPTR) + verbose_a("type=%s", dynptr_type_str(reg->dynptr.type)); if (tnum_is_const(reg->var_off)) { /* a pointer register with fixed offset */ if (reg->var_off.value) { @@ -702,8 +705,6 @@ static void print_reg_state(struct bpf_verifier_env *env, } } verbose(env, ")"); - -#undef verbose_a } void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_state *state, @@ -727,6 +728,7 @@ void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_st } for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { char types_buf[BPF_REG_SIZE + 1]; + const char *sep = ""; bool valid = false; u8 slot_type; int j; @@ -765,9 +767,14 @@ void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_st verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); print_liveness(env, reg->live); - verbose(env, "=dynptr_%s", dynptr_type_str(reg->dynptr.type)); + verbose(env, "=dynptr_%s(", dynptr_type_str(reg->dynptr.type)); + if (reg->id) + verbose_a("id=%d", reg->id); if (reg->ref_obj_id) - verbose(env, "(ref_id=%d)", reg->ref_obj_id); + verbose_a("ref_id=%d", reg->ref_obj_id); + if (reg->dynptr_id) + verbose_a("dynptr_id=%d", reg->dynptr_id); + verbose(env, ")"); break; case STACK_ITER: /* only main slot has ref_obj_id set; skip others */ -- cgit v1.2.3 From 1a1ad782dcbbacd9e8d4e2e7ff1bf14d1db80727 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 4 Dec 2023 15:39:21 -0800 Subject: bpf: tidy up exception callback management a bit Use the fact that we are passing subprog index around and have a corresponding struct bpf_subprog_info in bpf_verifier_env for each subprogram. We don't need to separately pass around a flag whether subprog is exception callback or not, each relevant verifier function can determine this using provided subprog index if we maintain bpf_subprog_info properly. Also move out exception callback-specific logic from btf_prepare_func_args(), keeping it generic. We can enforce all these restriction right before exception callback verification pass. We add out parameter, arg_cnt, for now, but this will be unnecessary with subsequent refactoring and will be removed. Signed-off-by: Andrii Nakryiko Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20231204233931.49758-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 2 +- kernel/bpf/btf.c | 11 ++--------- kernel/bpf/verifier.c | 52 ++++++++++++++++++++++++++++++++++++++------------- 3 files changed, 42 insertions(+), 23 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index c1a06263a4f3..0bd4889e917a 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2494,7 +2494,7 @@ int btf_check_subprog_arg_match(struct bpf_verifier_env *env, int subprog, int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog, struct bpf_reg_state *regs); int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog, - struct bpf_reg_state *reg, bool is_ex_cb); + struct bpf_reg_state *reg, u32 *nargs); int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *prog, struct btf *btf, const struct btf_type *t); const char *btf_find_decl_tag_value(const struct btf *btf, const struct btf_type *pt, diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 63cf4128fc05..d56433bf8aba 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6956,7 +6956,7 @@ int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog, * (either PTR_TO_CTX or SCALAR_VALUE). */ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog, - struct bpf_reg_state *regs, bool is_ex_cb) + struct bpf_reg_state *regs, u32 *arg_cnt) { struct bpf_verifier_log *log = &env->log; struct bpf_prog *prog = env->prog; @@ -7013,6 +7013,7 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog, tname, nargs, MAX_BPF_FUNC_REG_ARGS); return -EINVAL; } + *arg_cnt = nargs; /* check that function returns int, exception cb also requires this */ t = btf_type_by_id(btf, t->type); while (btf_type_is_modifier(t)) @@ -7062,14 +7063,6 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog, i, btf_type_str(t), tname); return -EINVAL; } - /* We have already ensured that the callback returns an integer, just - * like all global subprogs. We need to determine it only has a single - * scalar argument. - */ - if (is_ex_cb && (nargs != 1 || regs[BPF_REG_1].type != SCALAR_VALUE)) { - bpf_log(log, "exception cb only supports single integer argument\n"); - return -EINVAL; - } return 0; } diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 727a59e4a647..d1755db1b503 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -442,6 +442,25 @@ static struct bpf_func_info_aux *subprog_aux(const struct bpf_verifier_env *env, return &env->prog->aux->func_info_aux[subprog]; } +static struct bpf_subprog_info *subprog_info(struct bpf_verifier_env *env, int subprog) +{ + return &env->subprog_info[subprog]; +} + +static void mark_subprog_exc_cb(struct bpf_verifier_env *env, int subprog) +{ + struct bpf_subprog_info *info = subprog_info(env, subprog); + + info->is_cb = true; + info->is_async_cb = true; + info->is_exception_cb = true; +} + +static bool subprog_is_exc_cb(struct bpf_verifier_env *env, int subprog) +{ + return subprog_info(env, subprog)->is_exception_cb; +} + static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg) { return btf_record_has_field(reg_btf_record(reg), BPF_SPIN_LOCK); @@ -2892,6 +2911,7 @@ static int add_subprog_and_kfunc(struct bpf_verifier_env *env) if (env->subprog_info[i].start != ex_cb_insn) continue; env->exception_callback_subprog = i; + mark_subprog_exc_cb(env, i); break; } } @@ -19166,9 +19186,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env) env->exception_callback_subprog = env->subprog_cnt - 1; /* Don't update insn_cnt, as add_hidden_subprog always appends insns */ - env->subprog_info[env->exception_callback_subprog].is_cb = true; - env->subprog_info[env->exception_callback_subprog].is_async_cb = true; - env->subprog_info[env->exception_callback_subprog].is_exception_cb = true; + mark_subprog_exc_cb(env, env->exception_callback_subprog); } for (i = 0; i < insn_cnt; i++, insn++) { @@ -19868,7 +19886,7 @@ static void free_states(struct bpf_verifier_env *env) } } -static int do_check_common(struct bpf_verifier_env *env, int subprog, bool is_ex_cb) +static int do_check_common(struct bpf_verifier_env *env, int subprog) { bool pop_log = !(env->log.level & BPF_LOG_LEVEL2); struct bpf_verifier_state *state; @@ -19899,9 +19917,23 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog, bool is_ex regs = state->frame[state->curframe]->regs; if (subprog || env->prog->type == BPF_PROG_TYPE_EXT) { - ret = btf_prepare_func_args(env, subprog, regs, is_ex_cb); + u32 nargs; + + ret = btf_prepare_func_args(env, subprog, regs, &nargs); if (ret) goto out; + if (subprog_is_exc_cb(env, subprog)) { + state->frame[0]->in_exception_callback_fn = true; + /* We have already ensured that the callback returns an integer, just + * like all global subprogs. We need to determine it only has a single + * scalar argument. + */ + if (nargs != 1 || regs[BPF_REG_1].type != SCALAR_VALUE) { + verbose(env, "exception cb only supports single integer argument\n"); + ret = -EINVAL; + goto out; + } + } for (i = BPF_REG_1; i <= BPF_REG_5; i++) { if (regs[i].type == PTR_TO_CTX) mark_reg_known_zero(env, regs, i); @@ -19915,12 +19947,6 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog, bool is_ex regs[i].id = ++env->id_gen; } } - if (is_ex_cb) { - state->frame[0]->in_exception_callback_fn = true; - env->subprog_info[subprog].is_cb = true; - env->subprog_info[subprog].is_async_cb = true; - env->subprog_info[subprog].is_exception_cb = true; - } } else { /* 1st arg to a function */ regs[BPF_REG_1].type = PTR_TO_CTX; @@ -20000,7 +20026,7 @@ again: env->insn_idx = env->subprog_info[i].start; WARN_ON_ONCE(env->insn_idx == 0); - ret = do_check_common(env, i, env->exception_callback_subprog == i); + ret = do_check_common(env, i); if (ret) { return ret; } else if (env->log.level & BPF_LOG_LEVEL) { @@ -20030,7 +20056,7 @@ static int do_check_main(struct bpf_verifier_env *env) int ret; env->insn_idx = 0; - ret = do_check_common(env, 0, false); + ret = do_check_common(env, 0); if (!ret) env->prog->aux->stack_depth = env->subprog_info[0].stack_depth; return ret; -- cgit v1.2.3 From 56c26d5ad86dfe48a76855a91b523ab4f372c003 Mon Sep 17 00:00:00 2001 From: Yang Li Date: Tue, 12 Dec 2023 08:54:36 +0800 Subject: bpf: Remove unused backtrack_state helper functions The function are defined in the verifier.c file, but not called elsewhere, so delete the unused function. kernel/bpf/verifier.c:3448:20: warning: unused function 'bt_set_slot' kernel/bpf/verifier.c:3453:20: warning: unused function 'bt_clear_slot' kernel/bpf/verifier.c:3488:20: warning: unused function 'bt_is_slot_set' Reported-by: Abaci Robot Signed-off-by: Yang Li Signed-off-by: Andrii Nakryiko Acked-by: Eduard Zingerman Link: https://lore.kernel.org/bpf/20231212005436.103829-1-yang.lee@linux.alibaba.com Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=7714 --- kernel/bpf/verifier.c | 15 --------------- 1 file changed, 15 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index d1755db1b503..ef27820a24e3 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3465,16 +3465,6 @@ static inline void bt_clear_frame_slot(struct backtrack_state *bt, u32 frame, u3 bt->stack_masks[frame] &= ~(1ull << slot); } -static inline void bt_set_slot(struct backtrack_state *bt, u32 slot) -{ - bt_set_frame_slot(bt, bt->frame, slot); -} - -static inline void bt_clear_slot(struct backtrack_state *bt, u32 slot) -{ - bt_clear_frame_slot(bt, bt->frame, slot); -} - static inline u32 bt_frame_reg_mask(struct backtrack_state *bt, u32 frame) { return bt->reg_masks[frame]; @@ -3505,11 +3495,6 @@ static inline bool bt_is_frame_slot_set(struct backtrack_state *bt, u32 frame, u return bt->stack_masks[frame] & (1ull << slot); } -static inline bool bt_is_slot_set(struct backtrack_state *bt, u32 slot) -{ - return bt_is_frame_slot_set(bt, bt->frame, slot); -} - /* format registers bitmask, e.g., "r0,r2,r4" for 0x15 mask */ static void fmt_reg_mask(char *buf, ssize_t buf_sz, u32 reg_mask) { -- cgit v1.2.3 From 745e0311306507ddbe1727ac798c8f956812b810 Mon Sep 17 00:00:00 2001 From: Andrei Matei Date: Sun, 10 Dec 2023 17:51:50 -0500 Subject: bpf: Comment on check_mem_size_reg This patch adds a comment to check_mem_size_reg -- a function whose meaning is not very transparent. The function implicitly deals with two registers connected by convention, which is not obvious. Signed-off-by: Andrei Matei Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20231210225149.67639-1-andreimatei1@gmail.com --- kernel/bpf/verifier.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index ef27820a24e3..1863826a4ac3 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7256,6 +7256,12 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno, } } +/* verify arguments to helpers or kfuncs consisting of a pointer and an access + * size. + * + * @regno is the register containing the access size. regno-1 is the register + * containing the pointer. + */ static int check_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg, u32 regno, bool zero_size_allowed, -- cgit v1.2.3 From 750e785796bb72423b97cac21ecd0fa3b3b65610 Mon Sep 17 00:00:00 2001 From: Jie Jiang Date: Tue, 12 Dec 2023 09:39:23 +0000 Subject: bpf: Support uid and gid when mounting bpffs Parse uid and gid in bpf_parse_param() so that they can be passed in as the `data` parameter when mount() bpffs. This will be useful when we want to control which user/group has the control to the mounted bpffs, otherwise a separate chown() call will be needed. Signed-off-by: Jie Jiang Signed-off-by: Andrii Nakryiko Acked-by: Mike Frysinger Acked-by: Christian Brauner Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20231212093923.497838-1-jiejiang@chromium.org --- include/linux/bpf.h | 2 ++ kernel/bpf/inode.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 51 insertions(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 0bd4889e917a..c87c608a3689 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1595,6 +1595,8 @@ struct bpf_link_primer { }; struct bpf_mount_opts { + kuid_t uid; + kgid_t gid; umode_t mode; /* BPF token-related delegation options */ diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c index 5359a0929c35..0a8e1188ea46 100644 --- a/kernel/bpf/inode.c +++ b/kernel/bpf/inode.c @@ -601,9 +601,16 @@ EXPORT_SYMBOL(bpf_prog_get_type_path); static int bpf_show_options(struct seq_file *m, struct dentry *root) { struct bpf_mount_opts *opts = root->d_sb->s_fs_info; - umode_t mode = d_inode(root)->i_mode & S_IALLUGO & ~S_ISVTX; + struct inode *inode = d_inode(root); + umode_t mode = inode->i_mode & S_IALLUGO & ~S_ISVTX; u64 mask; + if (!uid_eq(inode->i_uid, GLOBAL_ROOT_UID)) + seq_printf(m, ",uid=%u", + from_kuid_munged(&init_user_ns, inode->i_uid)); + if (!gid_eq(inode->i_gid, GLOBAL_ROOT_GID)) + seq_printf(m, ",gid=%u", + from_kgid_munged(&init_user_ns, inode->i_gid)); if (mode != S_IRWXUGO) seq_printf(m, ",mode=%o", mode); @@ -652,6 +659,8 @@ const struct super_operations bpf_super_ops = { }; enum { + OPT_UID, + OPT_GID, OPT_MODE, OPT_DELEGATE_CMDS, OPT_DELEGATE_MAPS, @@ -660,6 +669,8 @@ enum { }; static const struct fs_parameter_spec bpf_fs_parameters[] = { + fsparam_u32 ("uid", OPT_UID), + fsparam_u32 ("gid", OPT_GID), fsparam_u32oct ("mode", OPT_MODE), fsparam_string ("delegate_cmds", OPT_DELEGATE_CMDS), fsparam_string ("delegate_maps", OPT_DELEGATE_MAPS), @@ -672,6 +683,8 @@ static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param) { struct bpf_mount_opts *opts = fc->s_fs_info; struct fs_parse_result result; + kuid_t uid; + kgid_t gid; int opt, err; u64 msk; @@ -694,6 +707,34 @@ static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param) } switch (opt) { + case OPT_UID: + uid = make_kuid(current_user_ns(), result.uint_32); + if (!uid_valid(uid)) + goto bad_value; + + /* + * The requested uid must be representable in the + * filesystem's idmapping. + */ + if (!kuid_has_mapping(fc->user_ns, uid)) + goto bad_value; + + opts->uid = uid; + break; + case OPT_GID: + gid = make_kgid(current_user_ns(), result.uint_32); + if (!gid_valid(gid)) + goto bad_value; + + /* + * The requested gid must be representable in the + * filesystem's idmapping. + */ + if (!kgid_has_mapping(fc->user_ns, gid)) + goto bad_value; + + opts->gid = gid; + break; case OPT_MODE: opts->mode = result.uint_32 & S_IALLUGO; break; @@ -722,6 +763,9 @@ static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param) } return 0; + +bad_value: + return invalfc(fc, "Bad value for '%s'", param->key); } struct bpf_preload_ops *bpf_preload_ops; @@ -808,6 +852,8 @@ static int bpf_fill_super(struct super_block *sb, struct fs_context *fc) sb->s_op = &bpf_super_ops; inode = sb->s_root->d_inode; + inode->i_uid = opts->uid; + inode->i_gid = opts->gid; inode->i_op = &bpf_dir_iops; inode->i_mode &= ~S_IALLUGO; populate_bpffs(sb->s_root); @@ -843,6 +889,8 @@ static int bpf_init_fs_context(struct fs_context *fc) return -ENOMEM; opts->mode = S_IRWXUGO; + opts->uid = current_fsuid(); + opts->gid = current_fsgid(); /* start out with no BPF token delegation enabled */ opts->delegate_cmds = 0; -- cgit v1.2.3 From f5fdb51fb980077a4c6c78f3f775821f611fb38b Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 13 Dec 2023 11:08:33 -0800 Subject: bpf: fail BPF_TOKEN_CREATE if no delegation option was set on BPF FS It's quite confusing in practice when it's possible to successfully create a BPF token from BPF FS that didn't have any of delegate_xxx mount options set up. While it's not wrong, it's actually more meaningful to reject BPF_TOKEN_CREATE with specific error code (-ENOENT) to let user-space know that no token delegation is setup up. So, instead of creating empty BPF token that will be always ignored because it doesn't have any of the allow_xxx bits set, reject it with -ENOENT. If we ever need empty BPF token to be possible, we can support that with extra flag passed into BPF_TOKEN_CREATE. Acked-by: Christian Brauner Acked-by: John Fastabend Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231213190842.3844987-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/token.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/token.c b/kernel/bpf/token.c index 17212efcde60..a86fccd57e2d 100644 --- a/kernel/bpf/token.c +++ b/kernel/bpf/token.c @@ -152,6 +152,15 @@ int bpf_token_create(union bpf_attr *attr) goto out_path; } + mnt_opts = path.dentry->d_sb->s_fs_info; + if (mnt_opts->delegate_cmds == 0 && + mnt_opts->delegate_maps == 0 && + mnt_opts->delegate_progs == 0 && + mnt_opts->delegate_attachs == 0) { + err = -ENOENT; /* no BPF token delegation is set up */ + goto out_path; + } + mode = S_IFREG | ((S_IRUSR | S_IWUSR) & ~current_umask()); inode = bpf_get_inode(path.mnt->mnt_sb, NULL, mode); if (IS_ERR(inode)) { @@ -181,7 +190,6 @@ int bpf_token_create(union bpf_attr *attr) /* remember bpffs owning userns for future ns_capable() checks */ token->userns = get_user_ns(userns); - mnt_opts = path.dentry->d_sb->s_fs_info; token->allowed_cmds = mnt_opts->delegate_cmds; token->allowed_maps = mnt_opts->delegate_maps; token->allowed_progs = mnt_opts->delegate_progs; -- cgit v1.2.3 From b13cddf633562b9b2c34fd63471d377019704ebe Mon Sep 17 00:00:00 2001 From: Matt Bobrowski Date: Fri, 8 Dec 2023 15:32:48 +0000 Subject: bpf: add small subset of SECURITY_PATH hooks to BPF sleepable_lsm_hooks list security_path_* based LSM hooks appear to be generally missing from the sleepable_lsm_hooks list. Initially add a small subset of them to the preexisting sleepable_lsm_hooks list so that sleepable BPF helpers like bpf_d_path() can be used from sleepable BPF LSM based programs. The security_path_* hooks added in this patch are similar to the security_inode_* counterparts that already exist in the sleepable_lsm_hooks list, and are called in roughly similar points and contexts. Presumably, making them OK to be also annotated as sleepable. Building a kernel with DEBUG_ATOMIC_SLEEP options enabled and running reasonable workloads stimulating activity that would be intercepted by such security hooks didn't show any splats. Notably, I haven't added all the security_path_* LSM hooks that are available as I don't need them at this point in time. Signed-off-by: Matt Bobrowski Acked-by: KP Singh Link: https://lore.kernel.org/r/ZXM3IHHXpNY9y82a@google.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/bpf_lsm.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index 7d2f96413a57..63b4dc495125 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -304,6 +304,18 @@ BTF_ID(func, bpf_lsm_kernel_module_request) BTF_ID(func, bpf_lsm_kernel_read_file) BTF_ID(func, bpf_lsm_kernfs_init_security) +#ifdef CONFIG_SECURITY_PATH +BTF_ID(func, bpf_lsm_path_unlink) +BTF_ID(func, bpf_lsm_path_mkdir) +BTF_ID(func, bpf_lsm_path_rmdir) +BTF_ID(func, bpf_lsm_path_truncate) +BTF_ID(func, bpf_lsm_path_symlink) +BTF_ID(func, bpf_lsm_path_link) +BTF_ID(func, bpf_lsm_path_rename) +BTF_ID(func, bpf_lsm_path_chmod) +BTF_ID(func, bpf_lsm_path_chown) +#endif /* CONFIG_SECURITY_PATH */ + #ifdef CONFIG_KEYS BTF_ID(func, bpf_lsm_key_free) #endif /* CONFIG_KEYS */ -- cgit v1.2.3 From 2a0c6b41eec90c2a138ea8b574836744783c67ff Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Mon, 11 Dec 2023 16:34:47 +0800 Subject: bpf: Update the comments in maybe_wait_bpf_programs() Since commit 638e4b825d52 ("bpf: Allows per-cpu maps and map-in-map in sleepable programs"), sleepable BPF program can also use map-in-map, but maybe_wait_bpf_programs() doesn't handle it accordingly. The main reason is that using synchronize_rcu_tasks_trace() to wait for the completions of these sleepable BPF programs may incur a very long delay and userspace may think it is hung, so the wait for sleepable BPF programs is skipped. Update the comments in maybe_wait_bpf_programs() to reflect the reason. Signed-off-by: Hou Tao Acked-by: Yonghong Song Acked-by: John Fastabend Link: https://lore.kernel.org/r/20231211083447.1921178-1-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/syscall.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 06320d9abf33..d63c1ed42412 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -142,9 +142,13 @@ static u32 bpf_map_value_size(const struct bpf_map *map) static void maybe_wait_bpf_programs(struct bpf_map *map) { - /* Wait for any running BPF programs to complete so that - * userspace, when we return to it, knows that all programs - * that could be running use the new map value. + /* Wait for any running non-sleepable BPF programs to complete so that + * userspace, when we return to it, knows that all non-sleepable + * programs that could be running use the new map value. For sleepable + * BPF programs, synchronize_rcu_tasks_trace() should be used to wait + * for the completions of these programs, but considering the waiting + * time can be very long and userspace may think it will hang forever, + * so don't handle sleepable BPF programs now. */ if (map->map_type == BPF_MAP_TYPE_HASH_OF_MAPS || map->map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS) -- cgit v1.2.3 From 8f82583f9527b3be9d70d9a5d1f33435e29d0480 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Thu, 14 Dec 2023 12:30:09 +0800 Subject: bpf: Reduce the scope of rcu_read_lock when updating fd map There is no rcu-read-lock requirement for ops->map_fd_get_ptr() or ops->map_fd_put_ptr(), so doesn't use rcu-read-lock for these two callbacks. For bpf_fd_array_map_update_elem(), accessing array->ptrs doesn't need rcu-read-lock because array->ptrs must still be allocated. For bpf_fd_htab_map_update_elem(), htab_map_update_elem() only requires rcu-read-lock to be held to avoid the WARN_ON_ONCE(), so only use rcu_read_lock() during the invocation of htab_map_update_elem(). Acked-by: Yonghong Song Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20231214043010.3458072-2-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/hashtab.c | 6 ++++++ kernel/bpf/syscall.c | 4 ---- 2 files changed, 6 insertions(+), 4 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 5b9146fa825f..ec3bdcc6a3cf 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -2523,7 +2523,13 @@ int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file, if (IS_ERR(ptr)) return PTR_ERR(ptr); + /* The htab bucket lock is always held during update operations in fd + * htab map, and the following rcu_read_lock() is only used to avoid + * the WARN_ON_ONCE in htab_map_update_elem(). + */ + rcu_read_lock(); ret = htab_map_update_elem(map, key, &ptr, map_flags); + rcu_read_unlock(); if (ret) map->ops->map_fd_put_ptr(map, ptr, false); diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index d63c1ed42412..3fcf7741146a 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -184,15 +184,11 @@ static int bpf_map_update_value(struct bpf_map *map, struct file *map_file, err = bpf_percpu_cgroup_storage_update(map, key, value, flags); } else if (IS_FD_ARRAY(map)) { - rcu_read_lock(); err = bpf_fd_array_map_update_elem(map, map_file, key, value, flags); - rcu_read_unlock(); } else if (map->map_type == BPF_MAP_TYPE_HASH_OF_MAPS) { - rcu_read_lock(); err = bpf_fd_htab_map_update_elem(map, map_file, key, value, flags); - rcu_read_unlock(); } else if (map->map_type == BPF_MAP_TYPE_REUSEPORT_SOCKARRAY) { /* rcu_read_lock() is not needed */ err = bpf_fd_reuseport_array_update_elem(map, key, value, -- cgit v1.2.3 From dc68540913ac523b46ebda3843cec179362c7a72 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Thu, 14 Dec 2023 12:30:10 +0800 Subject: bpf: Use GFP_KERNEL in bpf_event_entry_gen() rcu_read_lock() is no longer held when invoking bpf_event_entry_gen() which is called by perf_event_fd_array_get_ptr(), so using GFP_KERNEL instead of GFP_ATOMIC to reduce the possibility of failures due to out-of-memory. Acked-by: Yonghong Song Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20231214043010.3458072-3-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/arraymap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 8d365bda9a8b..b5ec24b3563e 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -1195,7 +1195,7 @@ static struct bpf_event_entry *bpf_event_entry_gen(struct file *perf_file, { struct bpf_event_entry *ee; - ee = kzalloc(sizeof(*ee), GFP_ATOMIC); + ee = kzalloc(sizeof(*ee), GFP_KERNEL); if (ee) { ee->event = perf_file->private_data; ee->perf_file = perf_file; -- cgit v1.2.3 From 59e5791f59dd83e8aa72a4e74217eabb6e8cfd90 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Thu, 14 Dec 2023 12:38:15 -0800 Subject: bpf: Fix a race condition between btf_put() and map_free() When running `./test_progs -j` in my local vm with latest kernel, I once hit a kasan error like below: [ 1887.184724] BUG: KASAN: slab-use-after-free in bpf_rb_root_free+0x1f8/0x2b0 [ 1887.185599] Read of size 4 at addr ffff888106806910 by task kworker/u12:2/2830 [ 1887.186498] [ 1887.186712] CPU: 3 PID: 2830 Comm: kworker/u12:2 Tainted: G OEL 6.7.0-rc3-00699-g90679706d486-dirty #494 [ 1887.188034] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 [ 1887.189618] Workqueue: events_unbound bpf_map_free_deferred [ 1887.190341] Call Trace: [ 1887.190666] [ 1887.190949] dump_stack_lvl+0xac/0xe0 [ 1887.191423] ? nf_tcp_handle_invalid+0x1b0/0x1b0 [ 1887.192019] ? panic+0x3c0/0x3c0 [ 1887.192449] print_report+0x14f/0x720 [ 1887.192930] ? preempt_count_sub+0x1c/0xd0 [ 1887.193459] ? __virt_addr_valid+0xac/0x120 [ 1887.194004] ? bpf_rb_root_free+0x1f8/0x2b0 [ 1887.194572] kasan_report+0xc3/0x100 [ 1887.195085] ? bpf_rb_root_free+0x1f8/0x2b0 [ 1887.195668] bpf_rb_root_free+0x1f8/0x2b0 [ 1887.196183] ? __bpf_obj_drop_impl+0xb0/0xb0 [ 1887.196736] ? preempt_count_sub+0x1c/0xd0 [ 1887.197270] ? preempt_count_sub+0x1c/0xd0 [ 1887.197802] ? _raw_spin_unlock+0x1f/0x40 [ 1887.198319] bpf_obj_free_fields+0x1d4/0x260 [ 1887.198883] array_map_free+0x1a3/0x260 [ 1887.199380] bpf_map_free_deferred+0x7b/0xe0 [ 1887.199943] process_scheduled_works+0x3a2/0x6c0 [ 1887.200549] worker_thread+0x633/0x890 [ 1887.201047] ? __kthread_parkme+0xd7/0xf0 [ 1887.201574] ? kthread+0x102/0x1d0 [ 1887.202020] kthread+0x1ab/0x1d0 [ 1887.202447] ? pr_cont_work+0x270/0x270 [ 1887.202954] ? kthread_blkcg+0x50/0x50 [ 1887.203444] ret_from_fork+0x34/0x50 [ 1887.203914] ? kthread_blkcg+0x50/0x50 [ 1887.204397] ret_from_fork_asm+0x11/0x20 [ 1887.204913] [ 1887.204913] [ 1887.205209] [ 1887.205416] Allocated by task 2197: [ 1887.205881] kasan_set_track+0x3f/0x60 [ 1887.206366] __kasan_kmalloc+0x6e/0x80 [ 1887.206856] __kmalloc+0xac/0x1a0 [ 1887.207293] btf_parse_fields+0xa15/0x1480 [ 1887.207836] btf_parse_struct_metas+0x566/0x670 [ 1887.208387] btf_new_fd+0x294/0x4d0 [ 1887.208851] __sys_bpf+0x4ba/0x600 [ 1887.209292] __x64_sys_bpf+0x41/0x50 [ 1887.209762] do_syscall_64+0x4c/0xf0 [ 1887.210222] entry_SYSCALL_64_after_hwframe+0x63/0x6b [ 1887.210868] [ 1887.211074] Freed by task 36: [ 1887.211460] kasan_set_track+0x3f/0x60 [ 1887.211951] kasan_save_free_info+0x28/0x40 [ 1887.212485] ____kasan_slab_free+0x101/0x180 [ 1887.213027] __kmem_cache_free+0xe4/0x210 [ 1887.213514] btf_free+0x5b/0x130 [ 1887.213918] rcu_core+0x638/0xcc0 [ 1887.214347] __do_softirq+0x114/0x37e The error happens at bpf_rb_root_free+0x1f8/0x2b0: 00000000000034c0 : ; { 34c0: f3 0f 1e fa endbr64 34c4: e8 00 00 00 00 callq 0x34c9 34c9: 55 pushq %rbp 34ca: 48 89 e5 movq %rsp, %rbp ... ; if (rec && rec->refcount_off >= 0 && 36aa: 4d 85 ed testq %r13, %r13 36ad: 74 a9 je 0x3658 36af: 49 8d 7d 10 leaq 0x10(%r13), %rdi 36b3: e8 00 00 00 00 callq 0x36b8 <==== kasan function 36b8: 45 8b 7d 10 movl 0x10(%r13), %r15d <==== use-after-free load 36bc: 45 85 ff testl %r15d, %r15d 36bf: 78 8c js 0x364d So the problem is at rec->refcount_off in the above. I did some source code analysis and find the reason. CPU A CPU B bpf_map_put: ... btf_put with rcu callback ... bpf_map_free_deferred with system_unbound_wq ... ... ... ... btf_free_rcu: ... ... ... bpf_map_free_deferred: ... ... ... ---------> btf_struct_metas_free() ... | race condition ... ... ---------> map->ops->map_free() ... ... btf->struct_meta_tab = NULL In the above, map_free() corresponds to array_map_free() and eventually calling bpf_rb_root_free() which calls: ... __bpf_obj_drop_impl(obj, field->graph_root.value_rec, false); ... Here, 'value_rec' is assigned in btf_check_and_fixup_fields() with following code: meta = btf_find_struct_meta(btf, btf_id); if (!meta) return -EFAULT; rec->fields[i].graph_root.value_rec = meta->record; So basically, 'value_rec' is a pointer to the record in struct_metas_tab. And it is possible that that particular record has been freed by btf_struct_metas_free() and hence we have a kasan error here. Actually it is very hard to reproduce the failure with current bpf/bpf-next code, I only got the above error once. To increase reproducibility, I added a delay in bpf_map_free_deferred() to delay map->ops->map_free(), which significantly increased reproducibility. diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 5e43ddd1b83f..aae5b5213e93 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -695,6 +695,7 @@ static void bpf_map_free_deferred(struct work_struct *work) struct bpf_map *map = container_of(work, struct bpf_map, work); struct btf_record *rec = map->record; + mdelay(100); security_bpf_map_free(map); bpf_map_release_memcg(map); /* implementation dependent freeing */ Hao also provided test cases ([1]) for easily reproducing the above issue. There are two ways to fix the issue, the v1 of the patch ([2]) moving btf_put() after map_free callback, and the v5 of the patch ([3]) using a kptr style fix which tries to get a btf reference during map_check_btf(). Each approach has its pro and cons. The first approach delays freeing btf while the second approach needs to acquire reference depending on context which makes logic not very elegant and may complicate things with future new data structures. Alexei suggested in [4] going back to v1 which is what this patch tries to do. Rerun './test_progs -j' with the above mdelay() hack for a couple of times and didn't observe the error for the above rb_root test cases. Running Hou's test ([1]) is also successful. [1] https://lore.kernel.org/bpf/20231207141500.917136-1-houtao@huaweicloud.com/ [2] v1: https://lore.kernel.org/bpf/20231204173946.3066377-1-yonghong.song@linux.dev/ [3] v5: https://lore.kernel.org/bpf/20231208041621.2968241-1-yonghong.song@linux.dev/ [4] v4: https://lore.kernel.org/bpf/CAADnVQJ3FiXUhZJwX_81sjZvSYYKCFB3BT6P8D59RS2Gu+0Z7g@mail.gmail.com/ Cc: Hou Tao Fixes: 958cf2e273f0 ("bpf: Introduce bpf_obj_new") Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20231214203815.1469107-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov --- kernel/bpf/syscall.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 3fcf7741146a..8faa1a20edf8 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -692,6 +692,7 @@ static void bpf_map_free_deferred(struct work_struct *work) { struct bpf_map *map = container_of(work, struct bpf_map, work); struct btf_record *rec = map->record; + struct btf *btf = map->btf; security_bpf_map_free(map); bpf_map_release_memcg(map); @@ -707,6 +708,10 @@ static void bpf_map_free_deferred(struct work_struct *work) * template bpf_map struct used during verification. */ btf_record_free(rec); + /* Delay freeing of btf for maps, as map_free callback may need + * struct_meta info which will be freed with btf_put(). + */ + btf_put(btf); } static void bpf_map_put_uref(struct bpf_map *map) @@ -747,7 +752,6 @@ void bpf_map_put(struct bpf_map *map) if (atomic64_dec_and_test(&map->refcnt)) { /* bpf_map_free_id() must be called first */ bpf_map_free_id(map); - btf_put(map->btf); WARN_ON_ONCE(atomic64_read(&map->sleepable_refcnt)); if (READ_ONCE(map->free_after_mult_rcu_gp)) -- cgit v1.2.3 From c5707b2146d229691e193d5158ea70b21b8ba180 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 14 Dec 2023 14:50:15 -0800 Subject: bpf: support symbolic BPF FS delegation mount options Besides already supported special "any" value and hex bit mask, support string-based parsing of delegation masks based on exact enumerator names. Utilize BTF information of `enum bpf_cmd`, `enum bpf_map_type`, `enum bpf_prog_type`, and `enum bpf_attach_type` types to find supported symbolic names (ignoring __MAX_xxx guard values and stripping repetitive prefixes like BPF_ for cmd and attach types, BPF_MAP_TYPE_ for maps, and BPF_PROG_TYPE_ for prog types). The case doesn't matter, but it is normalized to lower case in mount option output. So "PROG_LOAD", "prog_load", and "MAP_create" are all valid values to specify for delegate_cmds options, "array" is among supported for map types, etc. Besides supporting string values, we also support multiple values specified at the same time, using colon (':') separator. There are corresponding changes on bpf_show_options side to use known values to print them in human-readable format, falling back to hex mask printing, if there are any unrecognized bits. This shouldn't be necessary when enum BTF information is present, but in general we should always be able to fall back to this even if kernel was built without BTF. As mentioned, emitted symbolic names are normalized to be all lower case. Example below shows various ways to specify delegate_cmds options through mount command and how mount options are printed back: 12/14 14:39:07.604 vmuser@archvm:~/local/linux/tools/testing/selftests/bpf $ mount | rg token $ sudo mkdir -p /sys/fs/bpf/token $ sudo mount -t bpf bpffs /sys/fs/bpf/token \ -o delegate_cmds=prog_load:MAP_CREATE \ -o delegate_progs=kprobe \ -o delegate_attachs=xdp $ mount | grep token bpffs on /sys/fs/bpf/token type bpf (rw,relatime,delegate_cmds=map_create:prog_load,delegate_progs=kprobe,delegate_attachs=xdp) Acked-by: John Fastabend Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231214225016.1209867-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/inode.c | 249 +++++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 211 insertions(+), 38 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c index 0a8e1188ea46..4383b3d13a55 100644 --- a/kernel/bpf/inode.c +++ b/kernel/bpf/inode.c @@ -595,6 +595,136 @@ struct bpf_prog *bpf_prog_get_type_path(const char *name, enum bpf_prog_type typ } EXPORT_SYMBOL(bpf_prog_get_type_path); +struct bpffs_btf_enums { + const struct btf *btf; + const struct btf_type *cmd_t; + const struct btf_type *map_t; + const struct btf_type *prog_t; + const struct btf_type *attach_t; +}; + +static int find_bpffs_btf_enums(struct bpffs_btf_enums *info) +{ + const struct btf *btf; + const struct btf_type *t; + const char *name; + int i, n; + + memset(info, 0, sizeof(*info)); + + btf = bpf_get_btf_vmlinux(); + if (IS_ERR(btf)) + return PTR_ERR(btf); + if (!btf) + return -ENOENT; + + info->btf = btf; + + for (i = 1, n = btf_nr_types(btf); i < n; i++) { + t = btf_type_by_id(btf, i); + if (!btf_type_is_enum(t)) + continue; + + name = btf_name_by_offset(btf, t->name_off); + if (!name) + continue; + + if (strcmp(name, "bpf_cmd") == 0) + info->cmd_t = t; + else if (strcmp(name, "bpf_map_type") == 0) + info->map_t = t; + else if (strcmp(name, "bpf_prog_type") == 0) + info->prog_t = t; + else if (strcmp(name, "bpf_attach_type") == 0) + info->attach_t = t; + else + continue; + + if (info->cmd_t && info->map_t && info->prog_t && info->attach_t) + return 0; + } + + return -ESRCH; +} + +static bool find_btf_enum_const(const struct btf *btf, const struct btf_type *enum_t, + const char *prefix, const char *str, int *value) +{ + const struct btf_enum *e; + const char *name; + int i, n, pfx_len = strlen(prefix); + + *value = 0; + + if (!btf || !enum_t) + return false; + + for (i = 0, n = btf_vlen(enum_t); i < n; i++) { + e = &btf_enum(enum_t)[i]; + + name = btf_name_by_offset(btf, e->name_off); + if (!name || strncasecmp(name, prefix, pfx_len) != 0) + continue; + + /* match symbolic name case insensitive and ignoring prefix */ + if (strcasecmp(name + pfx_len, str) == 0) { + *value = e->val; + return true; + } + } + + return false; +} + +static void seq_print_delegate_opts(struct seq_file *m, + const char *opt_name, + const struct btf *btf, + const struct btf_type *enum_t, + const char *prefix, + u64 delegate_msk, u64 any_msk) +{ + const struct btf_enum *e; + bool first = true; + const char *name; + u64 msk; + int i, n, pfx_len = strlen(prefix); + + delegate_msk &= any_msk; /* clear unknown bits */ + + if (delegate_msk == 0) + return; + + seq_printf(m, ",%s", opt_name); + if (delegate_msk == any_msk) { + seq_printf(m, "=any"); + return; + } + + if (btf && enum_t) { + for (i = 0, n = btf_vlen(enum_t); i < n; i++) { + e = &btf_enum(enum_t)[i]; + name = btf_name_by_offset(btf, e->name_off); + if (!name || strncasecmp(name, prefix, pfx_len) != 0) + continue; + msk = 1ULL << e->val; + if (delegate_msk & msk) { + /* emit lower-case name without prefix */ + seq_printf(m, "%c", first ? '=' : ':'); + name += pfx_len; + while (*name) { + seq_printf(m, "%c", tolower(*name)); + name++; + } + + delegate_msk &= ~msk; + first = false; + } + } + } + if (delegate_msk) + seq_printf(m, "%c0x%llx", first ? '=' : ':', delegate_msk); +} + /* * Display the mount options in /proc/mounts. */ @@ -614,29 +744,34 @@ static int bpf_show_options(struct seq_file *m, struct dentry *root) if (mode != S_IRWXUGO) seq_printf(m, ",mode=%o", mode); - mask = (1ULL << __MAX_BPF_CMD) - 1; - if ((opts->delegate_cmds & mask) == mask) - seq_printf(m, ",delegate_cmds=any"); - else if (opts->delegate_cmds) - seq_printf(m, ",delegate_cmds=0x%llx", opts->delegate_cmds); - - mask = (1ULL << __MAX_BPF_MAP_TYPE) - 1; - if ((opts->delegate_maps & mask) == mask) - seq_printf(m, ",delegate_maps=any"); - else if (opts->delegate_maps) - seq_printf(m, ",delegate_maps=0x%llx", opts->delegate_maps); - - mask = (1ULL << __MAX_BPF_PROG_TYPE) - 1; - if ((opts->delegate_progs & mask) == mask) - seq_printf(m, ",delegate_progs=any"); - else if (opts->delegate_progs) - seq_printf(m, ",delegate_progs=0x%llx", opts->delegate_progs); - - mask = (1ULL << __MAX_BPF_ATTACH_TYPE) - 1; - if ((opts->delegate_attachs & mask) == mask) - seq_printf(m, ",delegate_attachs=any"); - else if (opts->delegate_attachs) - seq_printf(m, ",delegate_attachs=0x%llx", opts->delegate_attachs); + if (opts->delegate_cmds || opts->delegate_maps || + opts->delegate_progs || opts->delegate_attachs) { + struct bpffs_btf_enums info; + + /* ignore errors, fallback to hex */ + (void)find_bpffs_btf_enums(&info); + + mask = (1ULL << __MAX_BPF_CMD) - 1; + seq_print_delegate_opts(m, "delegate_cmds", + info.btf, info.cmd_t, "BPF_", + opts->delegate_cmds, mask); + + mask = (1ULL << __MAX_BPF_MAP_TYPE) - 1; + seq_print_delegate_opts(m, "delegate_maps", + info.btf, info.map_t, "BPF_MAP_TYPE_", + opts->delegate_maps, mask); + + mask = (1ULL << __MAX_BPF_PROG_TYPE) - 1; + seq_print_delegate_opts(m, "delegate_progs", + info.btf, info.prog_t, "BPF_PROG_TYPE_", + opts->delegate_progs, mask); + + mask = (1ULL << __MAX_BPF_ATTACH_TYPE) - 1; + seq_print_delegate_opts(m, "delegate_attachs", + info.btf, info.attach_t, "BPF_", + opts->delegate_attachs, mask); + } + return 0; } @@ -686,7 +821,6 @@ static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param) kuid_t uid; kgid_t gid; int opt, err; - u64 msk; opt = fs_parse(fc, bpf_fs_parameters, param, &result); if (opt < 0) { @@ -741,24 +875,63 @@ static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param) case OPT_DELEGATE_CMDS: case OPT_DELEGATE_MAPS: case OPT_DELEGATE_PROGS: - case OPT_DELEGATE_ATTACHS: - if (strcmp(param->string, "any") == 0) { - msk = ~0ULL; - } else { - err = kstrtou64(param->string, 0, &msk); - if (err) - return err; + case OPT_DELEGATE_ATTACHS: { + struct bpffs_btf_enums info; + const struct btf_type *enum_t; + const char *enum_pfx; + u64 *delegate_msk, msk = 0; + char *p; + int val; + + /* ignore errors, fallback to hex */ + (void)find_bpffs_btf_enums(&info); + + switch (opt) { + case OPT_DELEGATE_CMDS: + delegate_msk = &opts->delegate_cmds; + enum_t = info.cmd_t; + enum_pfx = "BPF_"; + break; + case OPT_DELEGATE_MAPS: + delegate_msk = &opts->delegate_maps; + enum_t = info.map_t; + enum_pfx = "BPF_MAP_TYPE_"; + break; + case OPT_DELEGATE_PROGS: + delegate_msk = &opts->delegate_progs; + enum_t = info.prog_t; + enum_pfx = "BPF_PROG_TYPE_"; + break; + case OPT_DELEGATE_ATTACHS: + delegate_msk = &opts->delegate_attachs; + enum_t = info.attach_t; + enum_pfx = "BPF_"; + break; + default: + return -EINVAL; } + + while ((p = strsep(¶m->string, ":"))) { + if (strcmp(p, "any") == 0) { + msk |= ~0ULL; + } else if (find_btf_enum_const(info.btf, enum_t, enum_pfx, p, &val)) { + msk |= 1ULL << val; + } else { + err = kstrtou64(p, 0, &msk); + if (err) + return err; + } + } + /* Setting delegation mount options requires privileges */ if (msk && !capable(CAP_SYS_ADMIN)) return -EPERM; - switch (opt) { - case OPT_DELEGATE_CMDS: opts->delegate_cmds |= msk; break; - case OPT_DELEGATE_MAPS: opts->delegate_maps |= msk; break; - case OPT_DELEGATE_PROGS: opts->delegate_progs |= msk; break; - case OPT_DELEGATE_ATTACHS: opts->delegate_attachs |= msk; break; - default: return -EINVAL; - } + + *delegate_msk |= msk; + break; + } + default: + /* ignore unknown mount options */ break; } -- cgit v1.2.3 From 7489723c2e26504573dbb49b66bbc59092840008 Mon Sep 17 00:00:00 2001 From: Daniel Xu Date: Thu, 14 Dec 2023 15:56:25 -0700 Subject: bpf: xdp: Register generic_kfunc_set with XDP programs Registering generic_kfunc_set with XDP programs enables some of the newer BPF features inside XDP -- namely tree based data structures and BPF exceptions. The current motivation for this commit is to enable assertions inside XDP bpf progs. Assertions are a standard and useful tool to encode intent. Signed-off-by: Daniel Xu Link: https://lore.kernel.org/r/d07d4614b81ca6aada44fcb89bb6b618fb66e4ca.1702594357.git.dxu@dxuuu.xyz Signed-off-by: Alexei Starovoitov --- kernel/bpf/helpers.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index b3be5742d6f1..b0b485126a76 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2630,6 +2630,7 @@ static int __init kfunc_init(void) ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &generic_kfunc_set); ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &generic_kfunc_set); + ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &generic_kfunc_set); ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &generic_kfunc_set); ret = ret ?: register_btf_id_dtor_kfuncs(generic_dtors, ARRAY_SIZE(generic_dtors), -- cgit v1.2.3 From 4f9087f16651aca4a5f32da840a53f6660f0579a Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 15 Dec 2023 10:12:18 +0100 Subject: x86/cfi,bpf: Fix BPF JIT call The current BPF call convention is __nocfi, except when it calls !JIT things, then it calls regular C functions. It so happens that with FineIBT the __nocfi and C calling conventions are incompatible. Specifically __nocfi will call at func+0, while FineIBT will have endbr-poison there, which is not a valid indirect target. Causing #CP. Notably this only triggers on IBT enabled hardware, which is probably why this hasn't been reported (also, most people will have JIT on anyway). Implement proper CFI prologues for the BPF JIT codegen and drop __nocfi for x86. Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20231215092707.345270396@infradead.org Signed-off-by: Alexei Starovoitov --- arch/x86/include/asm/cfi.h | 110 ++++++++++++++++++++++++++++++++++++++++++ arch/x86/kernel/alternative.c | 47 +++++++++++++++--- arch/x86/net/bpf_jit_comp.c | 82 +++++++++++++++++++++++++++++-- include/linux/bpf.h | 12 ++++- include/linux/cfi.h | 7 +++ kernel/bpf/core.c | 25 ++++++++++ 6 files changed, 269 insertions(+), 14 deletions(-) (limited to 'kernel/bpf') diff --git a/arch/x86/include/asm/cfi.h b/arch/x86/include/asm/cfi.h index 2a494643089d..7a7b0b823a98 100644 --- a/arch/x86/include/asm/cfi.h +++ b/arch/x86/include/asm/cfi.h @@ -9,15 +9,125 @@ */ #include +/* + * An overview of the various calling conventions... + * + * Traditional: + * + * foo: + * ... code here ... + * ret + * + * direct caller: + * call foo + * + * indirect caller: + * lea foo(%rip), %r11 + * ... + * call *%r11 + * + * + * IBT: + * + * foo: + * endbr64 + * ... code here ... + * ret + * + * direct caller: + * call foo / call foo+4 + * + * indirect caller: + * lea foo(%rip), %r11 + * ... + * call *%r11 + * + * + * kCFI: + * + * __cfi_foo: + * movl $0x12345678, %eax + * # 11 nops when CONFIG_CALL_PADDING + * foo: + * endbr64 # when IBT + * ... code here ... + * ret + * + * direct call: + * call foo # / call foo+4 when IBT + * + * indirect call: + * lea foo(%rip), %r11 + * ... + * movl $(-0x12345678), %r10d + * addl -4(%r11), %r10d # -15 when CONFIG_CALL_PADDING + * jz 1f + * ud2 + * 1:call *%r11 + * + * + * FineIBT (builds as kCFI + CALL_PADDING + IBT + RETPOLINE and runtime patches into): + * + * __cfi_foo: + * endbr64 + * subl 0x12345678, %r10d + * jz foo + * ud2 + * nop + * foo: + * osp nop3 # was endbr64 + * ... code here ... + * ret + * + * direct caller: + * call foo / call foo+4 + * + * indirect caller: + * lea foo(%rip), %r11 + * ... + * movl $0x12345678, %r10d + * subl $16, %r11 + * nop4 + * call *%r11 + * + */ +enum cfi_mode { + CFI_DEFAULT, /* FineIBT if hardware has IBT, otherwise kCFI */ + CFI_OFF, /* Taditional / IBT depending on .config */ + CFI_KCFI, /* Optionally CALL_PADDING, IBT, RETPOLINE */ + CFI_FINEIBT, /* see arch/x86/kernel/alternative.c */ +}; + +extern enum cfi_mode cfi_mode; + struct pt_regs; #ifdef CONFIG_CFI_CLANG enum bug_trap_type handle_cfi_failure(struct pt_regs *regs); +#define __bpfcall +extern u32 cfi_bpf_hash; + +static inline int cfi_get_offset(void) +{ + switch (cfi_mode) { + case CFI_FINEIBT: + return 16; + case CFI_KCFI: + if (IS_ENABLED(CONFIG_CALL_PADDING)) + return 16; + return 5; + default: + return 0; + } +} +#define cfi_get_offset cfi_get_offset + #else static inline enum bug_trap_type handle_cfi_failure(struct pt_regs *regs) { return BUG_TRAP_TYPE_NONE; } +#define cfi_bpf_hash 0U #endif /* CONFIG_CFI_CLANG */ #endif /* _ASM_X86_CFI_H */ diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 73be3931e4f0..d808d3aaec7e 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -30,6 +30,7 @@ #include #include #include +#include int __read_mostly alternatives_patched; @@ -832,15 +833,43 @@ void __init_or_module apply_seal_endbr(s32 *start, s32 *end) { } #endif /* CONFIG_X86_KERNEL_IBT */ #ifdef CONFIG_FINEIBT +#define __CFI_DEFAULT CFI_DEFAULT +#elif defined(CONFIG_CFI_CLANG) +#define __CFI_DEFAULT CFI_KCFI +#else +#define __CFI_DEFAULT CFI_OFF +#endif -enum cfi_mode { - CFI_DEFAULT, - CFI_OFF, - CFI_KCFI, - CFI_FINEIBT, -}; +enum cfi_mode cfi_mode __ro_after_init = __CFI_DEFAULT; + +#ifdef CONFIG_CFI_CLANG +struct bpf_insn; + +/* Must match bpf_func_t / DEFINE_BPF_PROG_RUN() */ +extern unsigned int __bpf_prog_runX(const void *ctx, + const struct bpf_insn *insn); + +/* + * Force a reference to the external symbol so the compiler generates + * __kcfi_typid. + */ +__ADDRESSABLE(__bpf_prog_runX); + +/* u32 __ro_after_init cfi_bpf_hash = __kcfi_typeid___bpf_prog_runX; */ +asm ( +" .pushsection .data..ro_after_init,\"aw\",@progbits \n" +" .type cfi_bpf_hash,@object \n" +" .globl cfi_bpf_hash \n" +" .p2align 2, 0x0 \n" +"cfi_bpf_hash: \n" +" .long __kcfi_typeid___bpf_prog_runX \n" +" .size cfi_bpf_hash, 4 \n" +" .popsection \n" +); +#endif + +#ifdef CONFIG_FINEIBT -static enum cfi_mode cfi_mode __ro_after_init = CFI_DEFAULT; static bool cfi_rand __ro_after_init = true; static u32 cfi_seed __ro_after_init; @@ -1149,8 +1178,10 @@ static void __apply_fineibt(s32 *start_retpoline, s32 *end_retpoline, goto err; if (cfi_rand) { - if (builtin) + if (builtin) { cfi_seed = get_random_u32(); + cfi_bpf_hash = cfi_rehash(cfi_bpf_hash); + } ret = cfi_rand_preamble(start_cfi, end_cfi); if (ret) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index af4a5de7d93a..5d5b967b111d 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -17,6 +17,7 @@ #include #include #include +#include static bool all_callee_regs_used[4] = {true, true, true, true}; @@ -51,9 +52,11 @@ static u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len) do { EMIT4(b1, b2, b3, b4); EMIT(off, 4); } while (0) #ifdef CONFIG_X86_KERNEL_IBT -#define EMIT_ENDBR() EMIT(gen_endbr(), 4) +#define EMIT_ENDBR() EMIT(gen_endbr(), 4) +#define EMIT_ENDBR_POISON() EMIT(gen_endbr_poison(), 4) #else #define EMIT_ENDBR() +#define EMIT_ENDBR_POISON() #endif static bool is_imm8(int value) @@ -304,6 +307,69 @@ static void pop_callee_regs(u8 **pprog, bool *callee_regs_used) *pprog = prog; } +/* + * Emit the various CFI preambles, see asm/cfi.h and the comments about FineIBT + * in arch/x86/kernel/alternative.c + */ + +static void emit_fineibt(u8 **pprog) +{ + u8 *prog = *pprog; + + EMIT_ENDBR(); + EMIT3_off32(0x41, 0x81, 0xea, cfi_bpf_hash); /* subl $hash, %r10d */ + EMIT2(0x74, 0x07); /* jz.d8 +7 */ + EMIT2(0x0f, 0x0b); /* ud2 */ + EMIT1(0x90); /* nop */ + EMIT_ENDBR_POISON(); + + *pprog = prog; +} + +static void emit_kcfi(u8 **pprog) +{ + u8 *prog = *pprog; + + EMIT1_off32(0xb8, cfi_bpf_hash); /* movl $hash, %eax */ +#ifdef CONFIG_CALL_PADDING + EMIT1(0x90); + EMIT1(0x90); + EMIT1(0x90); + EMIT1(0x90); + EMIT1(0x90); + EMIT1(0x90); + EMIT1(0x90); + EMIT1(0x90); + EMIT1(0x90); + EMIT1(0x90); + EMIT1(0x90); +#endif + EMIT_ENDBR(); + + *pprog = prog; +} + +static void emit_cfi(u8 **pprog) +{ + u8 *prog = *pprog; + + switch (cfi_mode) { + case CFI_FINEIBT: + emit_fineibt(&prog); + break; + + case CFI_KCFI: + emit_kcfi(&prog); + break; + + default: + EMIT_ENDBR(); + break; + } + + *pprog = prog; +} + /* * Emit x86-64 prologue code for BPF program. * bpf_tail_call helper will skip the first X86_TAIL_CALL_OFFSET bytes @@ -315,10 +381,10 @@ static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf, { u8 *prog = *pprog; + emit_cfi(&prog); /* BPF trampoline can be made to work without these nops, * but let's waste 5 bytes for now and optimize later */ - EMIT_ENDBR(); memcpy(prog, x86_nops[5], X86_PATCH_SIZE); prog += X86_PATCH_SIZE; if (!ebpf_from_cbpf) { @@ -3013,9 +3079,16 @@ out_image: jit_data->header = header; jit_data->rw_header = rw_header; } - prog->bpf_func = (void *)image; + /* + * ctx.prog_offset is used when CFI preambles put code *before* + * the function. See emit_cfi(). For FineIBT specifically this code + * can also be executed and bpf_prog_kallsyms_add() will + * generate an additional symbol to cover this, hence also + * decrement proglen. + */ + prog->bpf_func = (void *)image + cfi_get_offset(); prog->jited = 1; - prog->jited_len = proglen; + prog->jited_len = proglen - cfi_get_offset(); } else { prog = orig_prog; } @@ -3070,6 +3143,7 @@ void bpf_jit_free(struct bpf_prog *prog) kvfree(jit_data->addrs); kfree(jit_data); } + prog->bpf_func = (void *)prog->bpf_func - cfi_get_offset(); hdr = bpf_jit_binary_pack_hdr(prog); bpf_jit_binary_pack_free(hdr, NULL); WARN_ON_ONCE(!bpf_prog_kallsyms_verify_off(prog)); diff --git a/include/linux/bpf.h b/include/linux/bpf.h index c87c608a3689..9d84c376851a 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -29,6 +29,7 @@ #include #include #include +#include struct bpf_verifier_env; struct bpf_verifier_log; @@ -1211,7 +1212,11 @@ struct bpf_dispatcher { #endif }; -static __always_inline __nocfi unsigned int bpf_dispatcher_nop_func( +#ifndef __bpfcall +#define __bpfcall __nocfi +#endif + +static __always_inline __bpfcall unsigned int bpf_dispatcher_nop_func( const void *ctx, const struct bpf_insn *insnsi, bpf_func_t bpf_func) @@ -1303,7 +1308,7 @@ int arch_prepare_bpf_dispatcher(void *image, void *buf, s64 *funcs, int num_func #define DEFINE_BPF_DISPATCHER(name) \ __BPF_DISPATCHER_SC(name); \ - noinline __nocfi unsigned int bpf_dispatcher_##name##_func( \ + noinline __bpfcall unsigned int bpf_dispatcher_##name##_func( \ const void *ctx, \ const struct bpf_insn *insnsi, \ bpf_func_t bpf_func) \ @@ -1453,6 +1458,9 @@ struct bpf_prog_aux { struct bpf_kfunc_desc_tab *kfunc_tab; struct bpf_kfunc_btf_tab *kfunc_btf_tab; u32 size_poke_tab; +#ifdef CONFIG_FINEIBT + struct bpf_ksym ksym_prefix; +#endif struct bpf_ksym ksym; const struct bpf_prog_ops *ops; struct bpf_map **used_maps; diff --git a/include/linux/cfi.h b/include/linux/cfi.h index 2309d74e77e6..1ed2d96c0cfc 100644 --- a/include/linux/cfi.h +++ b/include/linux/cfi.h @@ -11,6 +11,13 @@ #include #include +#ifndef cfi_get_offset +static inline int cfi_get_offset(void) +{ + return 0; +} +#endif + #ifdef CONFIG_CFI_CLANG enum bug_trap_type report_cfi_failure(struct pt_regs *regs, unsigned long addr, unsigned long *target, u32 type); diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index c34513d645c4..5aa6863ac33b 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -121,6 +121,9 @@ struct bpf_prog *bpf_prog_alloc_no_stats(unsigned int size, gfp_t gfp_extra_flag #endif INIT_LIST_HEAD_RCU(&fp->aux->ksym.lnode); +#ifdef CONFIG_FINEIBT + INIT_LIST_HEAD_RCU(&fp->aux->ksym_prefix.lnode); +#endif mutex_init(&fp->aux->used_maps_mutex); mutex_init(&fp->aux->dst_mutex); @@ -683,6 +686,23 @@ void bpf_prog_kallsyms_add(struct bpf_prog *fp) fp->aux->ksym.prog = true; bpf_ksym_add(&fp->aux->ksym); + +#ifdef CONFIG_FINEIBT + /* + * When FineIBT, code in the __cfi_foo() symbols can get executed + * and hence unwinder needs help. + */ + if (cfi_mode != CFI_FINEIBT) + return; + + snprintf(fp->aux->ksym_prefix.name, KSYM_NAME_LEN, + "__cfi_%s", fp->aux->ksym.name); + + fp->aux->ksym_prefix.start = (unsigned long) fp->bpf_func - 16; + fp->aux->ksym_prefix.end = (unsigned long) fp->bpf_func; + + bpf_ksym_add(&fp->aux->ksym_prefix); +#endif } void bpf_prog_kallsyms_del(struct bpf_prog *fp) @@ -691,6 +711,11 @@ void bpf_prog_kallsyms_del(struct bpf_prog *fp) return; bpf_ksym_del(&fp->aux->ksym); +#ifdef CONFIG_FINEIBT + if (cfi_mode != CFI_FINEIBT) + return; + bpf_ksym_del(&fp->aux->ksym_prefix); +#endif } static struct bpf_ksym *bpf_ksym_find(unsigned long addr) -- cgit v1.2.3 From 2cd3e3772e41377f32d6eea643e0590774e9187c Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 15 Dec 2023 10:12:20 +0100 Subject: x86/cfi,bpf: Fix bpf_struct_ops CFI BPF struct_ops uses __arch_prepare_bpf_trampoline() to write trampolines for indirect function calls. These tramplines much have matching CFI. In order to obtain the correct CFI hash for the various methods, add a matching structure that contains stub functions, the compiler will generate correct CFI which we can pilfer for the trampolines. Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20231215092707.566977112@infradead.org Signed-off-by: Alexei Starovoitov --- arch/x86/include/asm/cfi.h | 6 ++++ arch/x86/kernel/alternative.c | 22 ++++++++++++++ arch/x86/net/bpf_jit_comp.c | 66 ++++++++++++++++++++++++++-------------- include/linux/bpf.h | 13 ++++++++ kernel/bpf/bpf_struct_ops.c | 16 +++++----- net/bpf/bpf_dummy_struct_ops.c | 31 ++++++++++++++++++- net/ipv4/bpf_tcp_ca.c | 69 ++++++++++++++++++++++++++++++++++++++++++ 7 files changed, 191 insertions(+), 32 deletions(-) (limited to 'kernel/bpf') diff --git a/arch/x86/include/asm/cfi.h b/arch/x86/include/asm/cfi.h index 8779abd217b7..1a50b2cd4713 100644 --- a/arch/x86/include/asm/cfi.h +++ b/arch/x86/include/asm/cfi.h @@ -123,6 +123,8 @@ static inline int cfi_get_offset(void) } #define cfi_get_offset cfi_get_offset +extern u32 cfi_get_func_hash(void *func); + #else static inline enum bug_trap_type handle_cfi_failure(struct pt_regs *regs) { @@ -130,6 +132,10 @@ static inline enum bug_trap_type handle_cfi_failure(struct pt_regs *regs) } #define cfi_bpf_hash 0U #define cfi_bpf_subprog_hash 0U +static inline u32 cfi_get_func_hash(void *func) +{ + return 0; +} #endif /* CONFIG_CFI_CLANG */ #endif /* _ASM_X86_CFI_H */ diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index cb393efd5ccd..49c2a62ba5e4 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -883,6 +883,28 @@ asm ( " .size cfi_bpf_subprog_hash, 4 \n" " .popsection \n" ); + +u32 cfi_get_func_hash(void *func) +{ + u32 hash; + + func -= cfi_get_offset(); + switch (cfi_mode) { + case CFI_FINEIBT: + func += 7; + break; + case CFI_KCFI: + func += 1; + break; + default: + return 0; + } + + if (get_kernel_nofault(hash, func)) + return 0; + + return hash; +} #endif #ifdef CONFIG_FINEIBT diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 43b8c08fdf8d..c89a4abdd726 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -312,9 +312,8 @@ static void pop_callee_regs(u8 **pprog, bool *callee_regs_used) * in arch/x86/kernel/alternative.c */ -static void emit_fineibt(u8 **pprog, bool is_subprog) +static void emit_fineibt(u8 **pprog, u32 hash) { - u32 hash = is_subprog ? cfi_bpf_subprog_hash : cfi_bpf_hash; u8 *prog = *pprog; EMIT_ENDBR(); @@ -327,9 +326,8 @@ static void emit_fineibt(u8 **pprog, bool is_subprog) *pprog = prog; } -static void emit_kcfi(u8 **pprog, bool is_subprog) +static void emit_kcfi(u8 **pprog, u32 hash) { - u32 hash = is_subprog ? cfi_bpf_subprog_hash : cfi_bpf_hash; u8 *prog = *pprog; EMIT1_off32(0xb8, hash); /* movl $hash, %eax */ @@ -351,17 +349,17 @@ static void emit_kcfi(u8 **pprog, bool is_subprog) *pprog = prog; } -static void emit_cfi(u8 **pprog, bool is_subprog) +static void emit_cfi(u8 **pprog, u32 hash) { u8 *prog = *pprog; switch (cfi_mode) { case CFI_FINEIBT: - emit_fineibt(&prog, is_subprog); + emit_fineibt(&prog, hash); break; case CFI_KCFI: - emit_kcfi(&prog, is_subprog); + emit_kcfi(&prog, hash); break; default: @@ -383,7 +381,7 @@ static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf, { u8 *prog = *pprog; - emit_cfi(&prog, is_subprog); + emit_cfi(&prog, is_subprog ? cfi_bpf_subprog_hash : cfi_bpf_hash); /* BPF trampoline can be made to work without these nops, * but let's waste 5 bytes for now and optimize later */ @@ -2510,10 +2508,19 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im u8 *prog; bool save_ret; + /* + * F_INDIRECT is only compatible with F_RET_FENTRY_RET, it is + * explicitly incompatible with F_CALL_ORIG | F_SKIP_FRAME | F_IP_ARG + * because @func_addr. + */ + WARN_ON_ONCE((flags & BPF_TRAMP_F_INDIRECT) && + (flags & ~(BPF_TRAMP_F_INDIRECT | BPF_TRAMP_F_RET_FENTRY_RET))); + /* extra registers for struct arguments */ - for (i = 0; i < m->nr_args; i++) + for (i = 0; i < m->nr_args; i++) { if (m->arg_flags[i] & BTF_FMODEL_STRUCT_ARG) nr_regs += (m->arg_size[i] + 7) / 8 - 1; + } /* x86-64 supports up to MAX_BPF_FUNC_ARGS arguments. 1-6 * are passed through regs, the remains are through stack. @@ -2596,20 +2603,27 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im prog = rw_image; - EMIT_ENDBR(); - /* - * This is the direct-call trampoline, as such it needs accounting - * for the __fentry__ call. - */ - x86_call_depth_emit_accounting(&prog, NULL); + if (flags & BPF_TRAMP_F_INDIRECT) { + /* + * Indirect call for bpf_struct_ops + */ + emit_cfi(&prog, cfi_get_func_hash(func_addr)); + } else { + /* + * Direct-call fentry stub, as such it needs accounting for the + * __fentry__ call. + */ + x86_call_depth_emit_accounting(&prog, NULL); + } EMIT1(0x55); /* push rbp */ EMIT3(0x48, 0x89, 0xE5); /* mov rbp, rsp */ - if (!is_imm8(stack_size)) + if (!is_imm8(stack_size)) { /* sub rsp, stack_size */ EMIT3_off32(0x48, 0x81, 0xEC, stack_size); - else + } else { /* sub rsp, stack_size */ EMIT4(0x48, 0x83, 0xEC, stack_size); + } if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) EMIT1(0x50); /* push rax */ /* mov QWORD PTR [rbp - rbx_off], rbx */ @@ -2643,10 +2657,11 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im } } - if (fentry->nr_links) + if (fentry->nr_links) { if (invoke_bpf(m, &prog, fentry, regs_off, run_ctx_off, flags & BPF_TRAMP_F_RET_FENTRY_RET, image, rw_image)) return -EINVAL; + } if (fmod_ret->nr_links) { branches = kcalloc(fmod_ret->nr_links, sizeof(u8 *), @@ -2665,11 +2680,12 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im restore_regs(m, &prog, regs_off); save_args(m, &prog, arg_stack_off, true); - if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) + if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) { /* Before calling the original function, restore the * tail_call_cnt from stack to rax. */ RESTORE_TAIL_CALL_CNT(stack_size); + } if (flags & BPF_TRAMP_F_ORIG_STACK) { emit_ldx(&prog, BPF_DW, BPF_REG_6, BPF_REG_FP, 8); @@ -2698,17 +2714,19 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im /* Update the branches saved in invoke_bpf_mod_ret with the * aligned address of do_fexit. */ - for (i = 0; i < fmod_ret->nr_links; i++) + for (i = 0; i < fmod_ret->nr_links; i++) { emit_cond_near_jump(&branches[i], image + (prog - (u8 *)rw_image), image + (branches[i] - (u8 *)rw_image), X86_JNE); + } } - if (fexit->nr_links) + if (fexit->nr_links) { if (invoke_bpf(m, &prog, fexit, regs_off, run_ctx_off, false, image, rw_image)) { ret = -EINVAL; goto cleanup; } + } if (flags & BPF_TRAMP_F_RESTORE_REGS) restore_regs(m, &prog, regs_off); @@ -2725,11 +2743,12 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im ret = -EINVAL; goto cleanup; } - } else if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) + } else if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) { /* Before running the original function, restore the * tail_call_cnt from stack to rax. */ RESTORE_TAIL_CALL_CNT(stack_size); + } /* restore return value of orig_call or fentry prog back into RAX */ if (save_ret) @@ -2737,9 +2756,10 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im emit_ldx(&prog, BPF_DW, BPF_REG_6, BPF_REG_FP, -rbx_off); EMIT1(0xC9); /* leave */ - if (flags & BPF_TRAMP_F_SKIP_FRAME) + if (flags & BPF_TRAMP_F_SKIP_FRAME) { /* skip our return address and return to parent */ EMIT4(0x48, 0x83, 0xC4, 8); /* add rsp, 8 */ + } emit_return(&prog, image + (prog - (u8 *)rw_image)); /* Make sure the trampoline generation logic doesn't overflow */ if (WARN_ON_ONCE(prog > (u8 *)rw_image_end - BPF_INSN_SAFETY)) { diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 9d84c376851a..db46b3359bf5 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1060,6 +1060,17 @@ struct btf_func_model { */ #define BPF_TRAMP_F_TAIL_CALL_CTX BIT(7) +/* + * Indicate the trampoline should be suitable to receive indirect calls; + * without this indirectly calling the generated code can result in #UD/#CP, + * depending on the CFI options. + * + * Used by bpf_struct_ops. + * + * Incompatible with FENTRY usage, overloads @func_addr argument. + */ +#define BPF_TRAMP_F_INDIRECT BIT(8) + /* Each call __bpf_prog_enter + call bpf_func + call __bpf_prog_exit is ~50 * bytes on x86. */ @@ -1697,6 +1708,7 @@ struct bpf_struct_ops { struct btf_func_model func_models[BPF_STRUCT_OPS_MAX_NR_MEMBERS]; u32 type_id; u32 value_id; + void *cfi_stubs; }; #if defined(CONFIG_BPF_JIT) && defined(CONFIG_BPF_SYSCALL) @@ -1710,6 +1722,7 @@ int bpf_struct_ops_map_sys_lookup_elem(struct bpf_map *map, void *key, int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks, struct bpf_tramp_link *link, const struct btf_func_model *model, + void *stub_func, void *image, void *image_end); static inline bool bpf_try_module_get(const void *data, struct module *owner) { diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index 4d53c53fc5aa..02068bd0e4d9 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -352,17 +352,16 @@ const struct bpf_link_ops bpf_struct_ops_link_lops = { int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks, struct bpf_tramp_link *link, const struct btf_func_model *model, - void *image, void *image_end) + void *stub_func, void *image, void *image_end) { - u32 flags; + u32 flags = BPF_TRAMP_F_INDIRECT; int size; tlinks[BPF_TRAMP_FENTRY].links[0] = link; tlinks[BPF_TRAMP_FENTRY].nr_links = 1; - /* BPF_TRAMP_F_RET_FENTRY_RET is only used by bpf_struct_ops, - * and it must be used alone. - */ - flags = model->ret_size > 0 ? BPF_TRAMP_F_RET_FENTRY_RET : 0; + + if (model->ret_size > 0) + flags |= BPF_TRAMP_F_RET_FENTRY_RET; size = arch_bpf_trampoline_size(model, flags, tlinks, NULL); if (size < 0) @@ -370,7 +369,7 @@ int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks, if (size > (unsigned long)image_end - (unsigned long)image) return -E2BIG; return arch_prepare_bpf_trampoline(NULL, image, image_end, - model, flags, tlinks, NULL); + model, flags, tlinks, stub_func); } static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, @@ -504,11 +503,12 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, err = bpf_struct_ops_prepare_trampoline(tlinks, link, &st_ops->func_models[i], + *(void **)(st_ops->cfi_stubs + moff), image, image_end); if (err < 0) goto reset_unlock; - *(void **)(kdata + moff) = image; + *(void **)(kdata + moff) = image + cfi_get_offset(); image += err; /* put prog_id to udata */ diff --git a/net/bpf/bpf_dummy_struct_ops.c b/net/bpf/bpf_dummy_struct_ops.c index 2748f9d77b18..8906f7bdf4a9 100644 --- a/net/bpf/bpf_dummy_struct_ops.c +++ b/net/bpf/bpf_dummy_struct_ops.c @@ -12,6 +12,11 @@ extern struct bpf_struct_ops bpf_bpf_dummy_ops; /* A common type for test_N with return value in bpf_dummy_ops */ typedef int (*dummy_ops_test_ret_fn)(struct bpf_dummy_ops_state *state, ...); +static int dummy_ops_test_ret_function(struct bpf_dummy_ops_state *state, ...) +{ + return 0; +} + struct bpf_dummy_ops_test_args { u64 args[MAX_BPF_FUNC_ARGS]; struct bpf_dummy_ops_state state; @@ -62,7 +67,7 @@ static int dummy_ops_copy_args(struct bpf_dummy_ops_test_args *args) static int dummy_ops_call_op(void *image, struct bpf_dummy_ops_test_args *args) { - dummy_ops_test_ret_fn test = (void *)image; + dummy_ops_test_ret_fn test = (void *)image + cfi_get_offset(); struct bpf_dummy_ops_state *state = NULL; /* state needs to be NULL if args[0] is 0 */ @@ -119,6 +124,7 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr, op_idx = prog->expected_attach_type; err = bpf_struct_ops_prepare_trampoline(tlinks, link, &st_ops->func_models[op_idx], + &dummy_ops_test_ret_function, image, image + PAGE_SIZE); if (err < 0) goto out; @@ -219,6 +225,28 @@ static void bpf_dummy_unreg(void *kdata) { } +static int bpf_dummy_test_1(struct bpf_dummy_ops_state *cb) +{ + return 0; +} + +static int bpf_dummy_test_2(struct bpf_dummy_ops_state *cb, int a1, unsigned short a2, + char a3, unsigned long a4) +{ + return 0; +} + +static int bpf_dummy_test_sleepable(struct bpf_dummy_ops_state *cb) +{ + return 0; +} + +static struct bpf_dummy_ops __bpf_bpf_dummy_ops = { + .test_1 = bpf_dummy_test_1, + .test_2 = bpf_dummy_test_2, + .test_sleepable = bpf_dummy_test_sleepable, +}; + struct bpf_struct_ops bpf_bpf_dummy_ops = { .verifier_ops = &bpf_dummy_verifier_ops, .init = bpf_dummy_init, @@ -227,4 +255,5 @@ struct bpf_struct_ops bpf_bpf_dummy_ops = { .reg = bpf_dummy_reg, .unreg = bpf_dummy_unreg, .name = "bpf_dummy_ops", + .cfi_stubs = &__bpf_bpf_dummy_ops, }; diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c index c7bbd8f3c708..634cfafa583d 100644 --- a/net/ipv4/bpf_tcp_ca.c +++ b/net/ipv4/bpf_tcp_ca.c @@ -271,6 +271,74 @@ static int bpf_tcp_ca_validate(void *kdata) return tcp_validate_congestion_control(kdata); } +static u32 bpf_tcp_ca_ssthresh(struct sock *sk) +{ + return 0; +} + +static void bpf_tcp_ca_cong_avoid(struct sock *sk, u32 ack, u32 acked) +{ +} + +static void bpf_tcp_ca_set_state(struct sock *sk, u8 new_state) +{ +} + +static void bpf_tcp_ca_cwnd_event(struct sock *sk, enum tcp_ca_event ev) +{ +} + +static void bpf_tcp_ca_in_ack_event(struct sock *sk, u32 flags) +{ +} + +static void bpf_tcp_ca_pkts_acked(struct sock *sk, const struct ack_sample *sample) +{ +} + +static u32 bpf_tcp_ca_min_tso_segs(struct sock *sk) +{ + return 0; +} + +static void bpf_tcp_ca_cong_control(struct sock *sk, const struct rate_sample *rs) +{ +} + +static u32 bpf_tcp_ca_undo_cwnd(struct sock *sk) +{ + return 0; +} + +static u32 bpf_tcp_ca_sndbuf_expand(struct sock *sk) +{ + return 0; +} + +static void __bpf_tcp_ca_init(struct sock *sk) +{ +} + +static void __bpf_tcp_ca_release(struct sock *sk) +{ +} + +static struct tcp_congestion_ops __bpf_ops_tcp_congestion_ops = { + .ssthresh = bpf_tcp_ca_ssthresh, + .cong_avoid = bpf_tcp_ca_cong_avoid, + .set_state = bpf_tcp_ca_set_state, + .cwnd_event = bpf_tcp_ca_cwnd_event, + .in_ack_event = bpf_tcp_ca_in_ack_event, + .pkts_acked = bpf_tcp_ca_pkts_acked, + .min_tso_segs = bpf_tcp_ca_min_tso_segs, + .cong_control = bpf_tcp_ca_cong_control, + .undo_cwnd = bpf_tcp_ca_undo_cwnd, + .sndbuf_expand = bpf_tcp_ca_sndbuf_expand, + + .init = __bpf_tcp_ca_init, + .release = __bpf_tcp_ca_release, +}; + struct bpf_struct_ops bpf_tcp_congestion_ops = { .verifier_ops = &bpf_tcp_ca_verifier_ops, .reg = bpf_tcp_ca_reg, @@ -281,6 +349,7 @@ struct bpf_struct_ops bpf_tcp_congestion_ops = { .init = bpf_tcp_ca_init, .validate = bpf_tcp_ca_validate, .name = "tcp_congestion_ops", + .cfi_stubs = &__bpf_ops_tcp_congestion_ops, }; static int __init bpf_tcp_ca_kfunc_init(void) -- cgit v1.2.3 From e4c00339891c074c76f626ac82981963cbba5332 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 15 Dec 2023 10:12:22 +0100 Subject: bpf: Fix dtor CFI Ensure the various dtor functions match their prototype and retain their CFI signatures, since they don't have their address taken, they are prone to not getting CFI, making them impossible to call indirectly. Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20231215092707.799451071@infradead.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/cpumask.c | 8 +++++++- kernel/bpf/helpers.c | 16 ++++++++++++++-- net/bpf/test_run.c | 15 +++++++++++++-- 3 files changed, 34 insertions(+), 5 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/cpumask.c b/kernel/bpf/cpumask.c index 7499b7d8c06f..2e73533a3811 100644 --- a/kernel/bpf/cpumask.c +++ b/kernel/bpf/cpumask.c @@ -96,6 +96,12 @@ __bpf_kfunc void bpf_cpumask_release(struct bpf_cpumask *cpumask) migrate_enable(); } +__bpf_kfunc void bpf_cpumask_release_dtor(void *cpumask) +{ + bpf_cpumask_release(cpumask); +} +CFI_NOSEAL(bpf_cpumask_release_dtor); + /** * bpf_cpumask_first() - Get the index of the first nonzero bit in the cpumask. * @cpumask: The cpumask being queried. @@ -453,7 +459,7 @@ static const struct btf_kfunc_id_set cpumask_kfunc_set = { BTF_ID_LIST(cpumask_dtor_ids) BTF_ID(struct, bpf_cpumask) -BTF_ID(func, bpf_cpumask_release) +BTF_ID(func, bpf_cpumask_release_dtor) static int __init cpumask_kfunc_init(void) { diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index b0b485126a76..e0c0e3676df8 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2150,6 +2150,12 @@ __bpf_kfunc void bpf_task_release(struct task_struct *p) put_task_struct_rcu_user(p); } +__bpf_kfunc void bpf_task_release_dtor(void *p) +{ + put_task_struct_rcu_user(p); +} +CFI_NOSEAL(bpf_task_release_dtor); + #ifdef CONFIG_CGROUPS /** * bpf_cgroup_acquire - Acquire a reference to a cgroup. A cgroup acquired by @@ -2174,6 +2180,12 @@ __bpf_kfunc void bpf_cgroup_release(struct cgroup *cgrp) cgroup_put(cgrp); } +__bpf_kfunc void bpf_cgroup_release_dtor(void *cgrp) +{ + cgroup_put(cgrp); +} +CFI_NOSEAL(bpf_cgroup_release_dtor); + /** * bpf_cgroup_ancestor - Perform a lookup on an entry in a cgroup's ancestor * array. A cgroup returned by this kfunc which is not subsequently stored in a @@ -2570,10 +2582,10 @@ static const struct btf_kfunc_id_set generic_kfunc_set = { BTF_ID_LIST(generic_dtor_ids) BTF_ID(struct, task_struct) -BTF_ID(func, bpf_task_release) +BTF_ID(func, bpf_task_release_dtor) #ifdef CONFIG_CGROUPS BTF_ID(struct, cgroup) -BTF_ID(func, bpf_cgroup_release) +BTF_ID(func, bpf_cgroup_release_dtor) #endif BTF_SET8_START(common_btf_ids) diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index 711cf5d59816..dfd919374017 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -600,10 +600,21 @@ __bpf_kfunc void bpf_kfunc_call_test_release(struct prog_test_ref_kfunc *p) refcount_dec(&p->cnt); } +__bpf_kfunc void bpf_kfunc_call_test_release_dtor(void *p) +{ + bpf_kfunc_call_test_release(p); +} +CFI_NOSEAL(bpf_kfunc_call_test_release_dtor); + __bpf_kfunc void bpf_kfunc_call_memb_release(struct prog_test_member *p) { } +__bpf_kfunc void bpf_kfunc_call_memb_release_dtor(void *p) +{ +} +CFI_NOSEAL(bpf_kfunc_call_memb_release_dtor); + __bpf_kfunc_end_defs(); BTF_SET8_START(bpf_test_modify_return_ids) @@ -1671,9 +1682,9 @@ static const struct btf_kfunc_id_set bpf_prog_test_kfunc_set = { BTF_ID_LIST(bpf_prog_test_dtor_kfunc_ids) BTF_ID(struct, prog_test_ref_kfunc) -BTF_ID(func, bpf_kfunc_call_test_release) +BTF_ID(func, bpf_kfunc_call_test_release_dtor) BTF_ID(struct, prog_test_member) -BTF_ID(func, bpf_kfunc_call_memb_release) +BTF_ID(func, bpf_kfunc_call_memb_release_dtor) static int __init bpf_prog_test_run_init(void) { -- cgit v1.2.3 From 852486b35f344887786d63250946dd921a05d7e8 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Fri, 15 Dec 2023 10:12:23 +0100 Subject: x86/cfi,bpf: Fix bpf_exception_cb() signature As per the earlier patches, BPF sub-programs have bpf_callback_t signature and CFI expects callers to have matching signature. This is violated by bpf_prog_aux::bpf_exception_cb(). [peterz: Changelog] Reported-by: Peter Zijlstra Signed-off-by: Alexei Starovoitov Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/CAADnVQ+Z7UcXXBBhMubhcMM=R-dExk-uHtfOLtoLxQ1XxEpqEA@mail.gmail.com Link: https://lore.kernel.org/r/20231215092707.910319166@infradead.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 2 +- kernel/bpf/helpers.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index db46b3359bf5..5e694934cf37 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1484,7 +1484,7 @@ struct bpf_prog_aux { int cgroup_atype; /* enum cgroup_bpf_attach_type */ struct bpf_map *cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]; char name[BPF_OBJ_NAME_LEN]; - unsigned int (*bpf_exception_cb)(u64 cookie, u64 sp, u64 bp); + u64 (*bpf_exception_cb)(u64 cookie, u64 sp, u64 bp, u64, u64); #ifdef CONFIG_SECURITY void *security; #endif diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index e0c0e3676df8..07fd4b5704f3 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2537,7 +2537,7 @@ __bpf_kfunc void bpf_throw(u64 cookie) * which skips compiler generated instrumentation to do the same. */ kasan_unpoison_task_stack_below((void *)(long)ctx.sp); - ctx.aux->bpf_exception_cb(cookie, ctx.sp, ctx.bp); + ctx.aux->bpf_exception_cb(cookie, ctx.sp, ctx.bp, 0, 0); WARN(1, "A call to BPF exception callback should never return\n"); } -- cgit v1.2.3 From 8e432e6197cef6250dfd6fdffd41c06613c874ca Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 18 Dec 2023 09:36:01 -0800 Subject: bpf: Ensure precise is reset to false in __mark_reg_const_zero() It is safe to always start with imprecise SCALAR_VALUE register. Previously __mark_reg_const_zero() relied on caller to reset precise mark, but it's very error prone and we already missed it in a few places. So instead make __mark_reg_const_zero() reset precision always, as it's a safe default for SCALAR_VALUE. Explanation is basically the same as for why we are resetting (or rather not setting) precision in current state. If necessary, precision propagation will set it to precise correctly. As such, also remove a big comment about forward precision propagation in mark_reg_stack_read() and avoid unnecessarily setting precision to true after reading from STACK_ZERO stack. Again, precision propagation will correctly handle this, if that SCALAR_VALUE register will ever be needed to be precise. Reported-by: Maxim Mikityanskiy Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Acked-by: Maxim Mikityanskiy Acked-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20231218173601.53047-1-andrii@kernel.org --- kernel/bpf/verifier.c | 29 ++++++++-------------- .../selftests/bpf/progs/verifier_spill_fill.c | 10 ++++++-- 2 files changed, 19 insertions(+), 20 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 1863826a4ac3..9456ee0ad129 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1777,10 +1777,14 @@ static void __mark_reg_known_zero(struct bpf_reg_state *reg) __mark_reg_known(reg, 0); } -static void __mark_reg_const_zero(struct bpf_reg_state *reg) +static void __mark_reg_const_zero(const struct bpf_verifier_env *env, struct bpf_reg_state *reg) { __mark_reg_known(reg, 0); reg->type = SCALAR_VALUE; + /* all scalars are assumed imprecise initially (unless unprivileged, + * in which case everything is forced to be precise) + */ + reg->precise = !env->bpf_capable; } static void mark_reg_known_zero(struct bpf_verifier_env *env, @@ -4706,21 +4710,10 @@ static void mark_reg_stack_read(struct bpf_verifier_env *env, zeros++; } if (zeros == max_off - min_off) { - /* any access_size read into register is zero extended, - * so the whole register == const_zero - */ - __mark_reg_const_zero(&state->regs[dst_regno]); - /* backtracking doesn't support STACK_ZERO yet, - * so mark it precise here, so that later - * backtracking can stop here. - * Backtracking may not need this if this register - * doesn't participate in pointer adjustment. - * Forward propagation of precise flag is not - * necessary either. This mark is only to stop - * backtracking. Any register that contributed - * to const 0 was marked precise before spill. + /* Any access_size read into register is zero extended, + * so the whole register == const_zero. */ - state->regs[dst_regno].precise = true; + __mark_reg_const_zero(env, &state->regs[dst_regno]); } else { /* have read misc data from the stack */ mark_reg_unknown(env, state->regs, dst_regno); @@ -4803,11 +4796,11 @@ static int check_stack_read_fixed_off(struct bpf_verifier_env *env, if (spill_cnt == size && tnum_is_const(reg->var_off) && reg->var_off.value == 0) { - __mark_reg_const_zero(&state->regs[dst_regno]); + __mark_reg_const_zero(env, &state->regs[dst_regno]); /* this IS register fill, so keep insn_flags */ } else if (zero_cnt == size) { /* similarly to mark_reg_stack_read(), preserve zeroes */ - __mark_reg_const_zero(&state->regs[dst_regno]); + __mark_reg_const_zero(env, &state->regs[dst_regno]); insn_flags = 0; /* not restoring original register state */ } else { mark_reg_unknown(env, state->regs, dst_regno); @@ -7963,7 +7956,7 @@ static int process_iter_next_call(struct bpf_verifier_env *env, int insn_idx, /* switch to DRAINED state, but keep the depth unchanged */ /* mark current iter state as drained and assume returned NULL */ cur_iter->iter.state = BPF_ITER_STATE_DRAINED; - __mark_reg_const_zero(&cur_fr->regs[BPF_REG_0]); + __mark_reg_const_zero(env, &cur_fr->regs[BPF_REG_0]); return 0; } diff --git a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c index 508f5d6c7347..39fe3372e0e0 100644 --- a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c +++ b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c @@ -499,8 +499,14 @@ __success __msg("2: (7a) *(u64 *)(r10 -8) = 0 ; R10=fp0 fp-8_w=00000000") /* but fp-16 is spilled IMPRECISE zero const reg */ __msg("4: (7b) *(u64 *)(r10 -16) = r0 ; R0_w=0 R10=fp0 fp-16_w=0") -/* and now check that precision propagation works even for such tricky case */ -__msg("10: (71) r2 = *(u8 *)(r10 -9) ; R2_w=P0 R10=fp0 fp-16_w=0") +/* validate that assigning R2 from STACK_ZERO doesn't mark register + * precise immediately; if necessary, it will be marked precise later + */ +__msg("6: (71) r2 = *(u8 *)(r10 -1) ; R2_w=0 R10=fp0 fp-8_w=00000000") +/* similarly, when R2 is assigned from spilled register, it is initially + * imprecise, but will be marked precise later once it is used in precise context + */ +__msg("10: (71) r2 = *(u8 *)(r10 -9) ; R2_w=0 R10=fp0 fp-16_w=0") __msg("11: (0f) r1 += r2") __msg("mark_precise: frame0: last_idx 11 first_idx 0 subseq_idx -1") __msg("mark_precise: frame0: regs=r2 stack= before 10: (71) r2 = *(u8 *)(r10 -9)") -- cgit v1.2.3 From d17aff807f845cf93926c28705216639c7279110 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 19 Dec 2023 07:37:35 -0800 Subject: Revert BPF token-related functionality This patch includes the following revert (one conflicting BPF FS patch and three token patch sets, represented by merge commits): - revert 0f5d5454c723 "Merge branch 'bpf-fs-mount-options-parsing-follow-ups'"; - revert 750e785796bb "bpf: Support uid and gid when mounting bpffs"; - revert 733763285acf "Merge branch 'bpf-token-support-in-libbpf-s-bpf-object'"; - revert c35919dcce28 "Merge branch 'bpf-token-and-bpf-fs-based-delegation'". Link: https://lore.kernel.org/bpf/CAHk-=wg7JuFYwGy=GOMbRCtOL+jwSQsdUaBsRWkDVYbxipbM5A@mail.gmail.com Signed-off-by: Andrii Nakryiko --- drivers/media/rc/bpf-lirc.c | 2 +- include/linux/bpf.h | 85 +- include/linux/filter.h | 2 +- include/linux/lsm_hook_defs.h | 15 +- include/linux/security.h | 43 +- include/uapi/linux/bpf.h | 42 - kernel/bpf/Makefile | 2 +- kernel/bpf/arraymap.c | 2 +- kernel/bpf/bpf_lsm.c | 15 +- kernel/bpf/cgroup.c | 6 +- kernel/bpf/core.c | 3 +- kernel/bpf/helpers.c | 6 +- kernel/bpf/inode.c | 326 +------ kernel/bpf/syscall.c | 215 ++-- kernel/bpf/token.c | 271 ----- kernel/bpf/verifier.c | 13 +- kernel/trace/bpf_trace.c | 2 +- net/core/filter.c | 36 +- net/ipv4/bpf_tcp_ca.c | 2 +- net/netfilter/nf_bpf_link.c | 2 +- security/security.c | 101 +- security/selinux/hooks.c | 47 +- tools/include/uapi/linux/bpf.h | 42 - tools/lib/bpf/Build | 2 +- tools/lib/bpf/bpf.c | 37 +- tools/lib/bpf/bpf.h | 35 +- tools/lib/bpf/btf.c | 7 +- tools/lib/bpf/elf.c | 2 + tools/lib/bpf/features.c | 478 --------- tools/lib/bpf/libbpf.c | 573 ++++++++--- tools/lib/bpf/libbpf.h | 37 +- tools/lib/bpf/libbpf.map | 1 - tools/lib/bpf/libbpf_internal.h | 36 +- tools/lib/bpf/libbpf_probes.c | 8 +- tools/lib/bpf/str_error.h | 3 - .../selftests/bpf/prog_tests/libbpf_probes.c | 4 - .../testing/selftests/bpf/prog_tests/libbpf_str.c | 6 - tools/testing/selftests/bpf/prog_tests/token.c | 1031 -------------------- tools/testing/selftests/bpf/progs/priv_map.c | 13 - tools/testing/selftests/bpf/progs/priv_prog.c | 13 - 40 files changed, 641 insertions(+), 2925 deletions(-) delete mode 100644 kernel/bpf/token.c delete mode 100644 tools/lib/bpf/features.c delete mode 100644 tools/testing/selftests/bpf/prog_tests/token.c delete mode 100644 tools/testing/selftests/bpf/progs/priv_map.c delete mode 100644 tools/testing/selftests/bpf/progs/priv_prog.c (limited to 'kernel/bpf') diff --git a/drivers/media/rc/bpf-lirc.c b/drivers/media/rc/bpf-lirc.c index 6d07693c6b9f..fe17c7f98e81 100644 --- a/drivers/media/rc/bpf-lirc.c +++ b/drivers/media/rc/bpf-lirc.c @@ -110,7 +110,7 @@ lirc_mode2_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_get_prandom_u32: return &bpf_get_prandom_u32_proto; case BPF_FUNC_trace_printk: - if (bpf_token_capable(prog->aux->token, CAP_PERFMON)) + if (perfmon_capable()) return bpf_get_trace_printk_proto(); fallthrough; default: diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 2f54cc0436c4..7a8d4c81a39a 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -52,10 +52,6 @@ struct module; struct bpf_func_state; struct ftrace_ops; struct cgroup; -struct bpf_token; -struct user_namespace; -struct super_block; -struct inode; extern struct idr btf_idr; extern spinlock_t btf_idr_lock; @@ -1488,7 +1484,6 @@ struct bpf_prog_aux { #ifdef CONFIG_SECURITY void *security; #endif - struct bpf_token *token; struct bpf_prog_offload *offload; struct btf *btf; struct bpf_func_info *func_info; @@ -1613,31 +1608,6 @@ struct bpf_link_primer { u32 id; }; -struct bpf_mount_opts { - kuid_t uid; - kgid_t gid; - umode_t mode; - - /* BPF token-related delegation options */ - u64 delegate_cmds; - u64 delegate_maps; - u64 delegate_progs; - u64 delegate_attachs; -}; - -struct bpf_token { - struct work_struct work; - atomic64_t refcnt; - struct user_namespace *userns; - u64 allowed_cmds; - u64 allowed_maps; - u64 allowed_progs; - u64 allowed_attachs; -#ifdef CONFIG_SECURITY - void *security; -#endif -}; - struct bpf_struct_ops_value; struct btf_member; @@ -2097,7 +2067,6 @@ static inline void bpf_enable_instrumentation(void) migrate_enable(); } -extern const struct super_operations bpf_super_ops; extern const struct file_operations bpf_map_fops; extern const struct file_operations bpf_prog_fops; extern const struct file_operations bpf_iter_fops; @@ -2232,26 +2201,24 @@ static inline void bpf_map_dec_elem_count(struct bpf_map *map) extern int sysctl_unprivileged_bpf_disabled; -bool bpf_token_capable(const struct bpf_token *token, int cap); - -static inline bool bpf_allow_ptr_leaks(const struct bpf_token *token) +static inline bool bpf_allow_ptr_leaks(void) { - return bpf_token_capable(token, CAP_PERFMON); + return perfmon_capable(); } -static inline bool bpf_allow_uninit_stack(const struct bpf_token *token) +static inline bool bpf_allow_uninit_stack(void) { - return bpf_token_capable(token, CAP_PERFMON); + return perfmon_capable(); } -static inline bool bpf_bypass_spec_v1(const struct bpf_token *token) +static inline bool bpf_bypass_spec_v1(void) { - return cpu_mitigations_off() || bpf_token_capable(token, CAP_PERFMON); + return cpu_mitigations_off() || perfmon_capable(); } -static inline bool bpf_bypass_spec_v4(const struct bpf_token *token) +static inline bool bpf_bypass_spec_v4(void) { - return cpu_mitigations_off() || bpf_token_capable(token, CAP_PERFMON); + return cpu_mitigations_off() || perfmon_capable(); } int bpf_map_new_fd(struct bpf_map *map, int flags); @@ -2268,21 +2235,8 @@ int bpf_link_new_fd(struct bpf_link *link); struct bpf_link *bpf_link_get_from_fd(u32 ufd); struct bpf_link *bpf_link_get_curr_or_next(u32 *id); -void bpf_token_inc(struct bpf_token *token); -void bpf_token_put(struct bpf_token *token); -int bpf_token_create(union bpf_attr *attr); -struct bpf_token *bpf_token_get_from_fd(u32 ufd); - -bool bpf_token_allow_cmd(const struct bpf_token *token, enum bpf_cmd cmd); -bool bpf_token_allow_map_type(const struct bpf_token *token, enum bpf_map_type type); -bool bpf_token_allow_prog_type(const struct bpf_token *token, - enum bpf_prog_type prog_type, - enum bpf_attach_type attach_type); - int bpf_obj_pin_user(u32 ufd, int path_fd, const char __user *pathname); int bpf_obj_get_user(int path_fd, const char __user *pathname, int flags); -struct inode *bpf_get_inode(struct super_block *sb, const struct inode *dir, - umode_t mode); #define BPF_ITER_FUNC_PREFIX "bpf_iter_" #define DEFINE_BPF_ITER_FUNC(target, args...) \ @@ -2526,8 +2480,7 @@ const char *btf_find_decl_tag_value(const struct btf *btf, const struct btf_type struct bpf_prog *bpf_prog_by_id(u32 id); struct bpf_link *bpf_link_by_id(u32 id); -const struct bpf_func_proto *bpf_base_func_proto(enum bpf_func_id func_id, - const struct bpf_prog *prog); +const struct bpf_func_proto *bpf_base_func_proto(enum bpf_func_id func_id); void bpf_task_storage_free(struct task_struct *task); void bpf_cgrp_storage_free(struct cgroup *cgroup); bool bpf_prog_has_kfunc_call(const struct bpf_prog *prog); @@ -2646,24 +2599,6 @@ static inline int bpf_obj_get_user(const char __user *pathname, int flags) return -EOPNOTSUPP; } -static inline bool bpf_token_capable(const struct bpf_token *token, int cap) -{ - return capable(cap) || (cap != CAP_SYS_ADMIN && capable(CAP_SYS_ADMIN)); -} - -static inline void bpf_token_inc(struct bpf_token *token) -{ -} - -static inline void bpf_token_put(struct bpf_token *token) -{ -} - -static inline struct bpf_token *bpf_token_get_from_fd(u32 ufd) -{ - return ERR_PTR(-EOPNOTSUPP); -} - static inline void __dev_flush(void) { } @@ -2787,7 +2722,7 @@ static inline int btf_struct_access(struct bpf_verifier_log *log, } static inline const struct bpf_func_proto * -bpf_base_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) +bpf_base_func_proto(enum bpf_func_id func_id) { return NULL; } diff --git a/include/linux/filter.h b/include/linux/filter.h index 12d907f17d36..68fb6c8142fe 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -1139,7 +1139,7 @@ static inline bool bpf_jit_blinding_enabled(struct bpf_prog *prog) return false; if (!bpf_jit_harden) return false; - if (bpf_jit_harden == 1 && bpf_token_capable(prog->aux->token, CAP_BPF)) + if (bpf_jit_harden == 1 && bpf_capable()) return false; return true; diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 3fdd00b452ac..ff217a5ce552 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -398,17 +398,10 @@ LSM_HOOK(void, LSM_RET_VOID, audit_rule_free, void *lsmrule) LSM_HOOK(int, 0, bpf, int cmd, union bpf_attr *attr, unsigned int size) LSM_HOOK(int, 0, bpf_map, struct bpf_map *map, fmode_t fmode) LSM_HOOK(int, 0, bpf_prog, struct bpf_prog *prog) -LSM_HOOK(int, 0, bpf_map_create, struct bpf_map *map, union bpf_attr *attr, - struct bpf_token *token) -LSM_HOOK(void, LSM_RET_VOID, bpf_map_free, struct bpf_map *map) -LSM_HOOK(int, 0, bpf_prog_load, struct bpf_prog *prog, union bpf_attr *attr, - struct bpf_token *token) -LSM_HOOK(void, LSM_RET_VOID, bpf_prog_free, struct bpf_prog *prog) -LSM_HOOK(int, 0, bpf_token_create, struct bpf_token *token, union bpf_attr *attr, - struct path *path) -LSM_HOOK(void, LSM_RET_VOID, bpf_token_free, struct bpf_token *token) -LSM_HOOK(int, 0, bpf_token_cmd, const struct bpf_token *token, enum bpf_cmd cmd) -LSM_HOOK(int, 0, bpf_token_capable, const struct bpf_token *token, int cap) +LSM_HOOK(int, 0, bpf_map_alloc_security, struct bpf_map *map) +LSM_HOOK(void, LSM_RET_VOID, bpf_map_free_security, struct bpf_map *map) +LSM_HOOK(int, 0, bpf_prog_alloc_security, struct bpf_prog_aux *aux) +LSM_HOOK(void, LSM_RET_VOID, bpf_prog_free_security, struct bpf_prog_aux *aux) #endif /* CONFIG_BPF_SYSCALL */ LSM_HOOK(int, 0, locked_down, enum lockdown_reason what) diff --git a/include/linux/security.h b/include/linux/security.h index 00809d2d5c38..1d1df326c881 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -32,7 +32,6 @@ #include #include #include -#include struct linux_binprm; struct cred; @@ -2021,22 +2020,15 @@ static inline void securityfs_remove(struct dentry *dentry) union bpf_attr; struct bpf_map; struct bpf_prog; -struct bpf_token; +struct bpf_prog_aux; #ifdef CONFIG_SECURITY extern int security_bpf(int cmd, union bpf_attr *attr, unsigned int size); extern int security_bpf_map(struct bpf_map *map, fmode_t fmode); extern int security_bpf_prog(struct bpf_prog *prog); -extern int security_bpf_map_create(struct bpf_map *map, union bpf_attr *attr, - struct bpf_token *token); +extern int security_bpf_map_alloc(struct bpf_map *map); extern void security_bpf_map_free(struct bpf_map *map); -extern int security_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, - struct bpf_token *token); -extern void security_bpf_prog_free(struct bpf_prog *prog); -extern int security_bpf_token_create(struct bpf_token *token, union bpf_attr *attr, - struct path *path); -extern void security_bpf_token_free(struct bpf_token *token); -extern int security_bpf_token_cmd(const struct bpf_token *token, enum bpf_cmd cmd); -extern int security_bpf_token_capable(const struct bpf_token *token, int cap); +extern int security_bpf_prog_alloc(struct bpf_prog_aux *aux); +extern void security_bpf_prog_free(struct bpf_prog_aux *aux); #else static inline int security_bpf(int cmd, union bpf_attr *attr, unsigned int size) @@ -2054,8 +2046,7 @@ static inline int security_bpf_prog(struct bpf_prog *prog) return 0; } -static inline int security_bpf_map_create(struct bpf_map *map, union bpf_attr *attr, - struct bpf_token *token) +static inline int security_bpf_map_alloc(struct bpf_map *map) { return 0; } @@ -2063,33 +2054,13 @@ static inline int security_bpf_map_create(struct bpf_map *map, union bpf_attr *a static inline void security_bpf_map_free(struct bpf_map *map) { } -static inline int security_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, - struct bpf_token *token) +static inline int security_bpf_prog_alloc(struct bpf_prog_aux *aux) { return 0; } -static inline void security_bpf_prog_free(struct bpf_prog *prog) +static inline void security_bpf_prog_free(struct bpf_prog_aux *aux) { } - -static inline int security_bpf_token_create(struct bpf_token *token, union bpf_attr *attr, - struct path *path) -{ - return 0; -} - -static inline void security_bpf_token_free(struct bpf_token *token) -{ } - -static inline int security_bpf_token_cmd(const struct bpf_token *token, enum bpf_cmd cmd) -{ - return 0; -} - -static inline int security_bpf_token_capable(const struct bpf_token *token, int cap) -{ - return 0; -} #endif /* CONFIG_SECURITY */ #endif /* CONFIG_BPF_SYSCALL */ diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 42f4d3090efe..754e68ca8744 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -847,36 +847,6 @@ union bpf_iter_link_info { * Returns zero on success. On error, -1 is returned and *errno* * is set appropriately. * - * BPF_TOKEN_CREATE - * Description - * Create BPF token with embedded information about what - * BPF-related functionality it allows: - * - a set of allowed bpf() syscall commands; - * - a set of allowed BPF map types to be created with - * BPF_MAP_CREATE command, if BPF_MAP_CREATE itself is allowed; - * - a set of allowed BPF program types and BPF program attach - * types to be loaded with BPF_PROG_LOAD command, if - * BPF_PROG_LOAD itself is allowed. - * - * BPF token is created (derived) from an instance of BPF FS, - * assuming it has necessary delegation mount options specified. - * This BPF token can be passed as an extra parameter to various - * bpf() syscall commands to grant BPF subsystem functionality to - * unprivileged processes. - * - * When created, BPF token is "associated" with the owning - * user namespace of BPF FS instance (super block) that it was - * derived from, and subsequent BPF operations performed with - * BPF token would be performing capabilities checks (i.e., - * CAP_BPF, CAP_PERFMON, CAP_NET_ADMIN, CAP_SYS_ADMIN) within - * that user namespace. Without BPF token, such capabilities - * have to be granted in init user namespace, making bpf() - * syscall incompatible with user namespace, for the most part. - * - * Return - * A new file descriptor (a nonnegative integer), or -1 if an - * error occurred (in which case, *errno* is set appropriately). - * * NOTES * eBPF objects (maps and programs) can be shared between processes. * @@ -931,8 +901,6 @@ enum bpf_cmd { BPF_ITER_CREATE, BPF_LINK_DETACH, BPF_PROG_BIND_MAP, - BPF_TOKEN_CREATE, - __MAX_BPF_CMD, }; enum bpf_map_type { @@ -983,7 +951,6 @@ enum bpf_map_type { BPF_MAP_TYPE_BLOOM_FILTER, BPF_MAP_TYPE_USER_RINGBUF, BPF_MAP_TYPE_CGRP_STORAGE, - __MAX_BPF_MAP_TYPE }; /* Note that tracing related programs such as @@ -1028,7 +995,6 @@ enum bpf_prog_type { BPF_PROG_TYPE_SK_LOOKUP, BPF_PROG_TYPE_SYSCALL, /* a program that can execute syscalls */ BPF_PROG_TYPE_NETFILTER, - __MAX_BPF_PROG_TYPE }; enum bpf_attach_type { @@ -1437,7 +1403,6 @@ union bpf_attr { * to using 5 hash functions). */ __u64 map_extra; - __u32 map_token_fd; }; struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */ @@ -1507,7 +1472,6 @@ union bpf_attr { * truncated), or smaller (if log buffer wasn't filled completely). */ __u32 log_true_size; - __u32 prog_token_fd; }; struct { /* anonymous struct used by BPF_OBJ_* commands */ @@ -1620,7 +1584,6 @@ union bpf_attr { * truncated), or smaller (if log buffer wasn't filled completely). */ __u32 btf_log_true_size; - __u32 btf_token_fd; }; struct { @@ -1751,11 +1714,6 @@ union bpf_attr { __u32 flags; /* extra flags */ } prog_bind_map; - struct { /* struct used by BPF_TOKEN_CREATE command */ - __u32 flags; - __u32 bpffs_fd; - } token_create; - } __attribute__((aligned(8))); /* The description below is an attempt at providing documentation to eBPF diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile index 4ce95acfcaa7..f526b7573e97 100644 --- a/kernel/bpf/Makefile +++ b/kernel/bpf/Makefile @@ -6,7 +6,7 @@ cflags-nogcse-$(CONFIG_X86)$(CONFIG_CC_IS_GCC) := -fno-gcse endif CFLAGS_core.o += $(call cc-disable-warning, override-init) $(cflags-nogcse-yy) -obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o log.o token.o +obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o log.o obj-$(CONFIG_BPF_SYSCALL) += bpf_iter.o map_iter.o task_iter.o prog_iter.o link_iter.o obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o lpm_trie.o map_in_map.o bloom_filter.o obj-$(CONFIG_BPF_SYSCALL) += local_storage.o queue_stack_maps.o ringbuf.o diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 13358675ff2e..0bdbbbeab155 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -82,7 +82,7 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr) bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY; int numa_node = bpf_map_attr_numa_node(attr); u32 elem_size, index_mask, max_entries; - bool bypass_spec_v1 = bpf_bypass_spec_v1(NULL); + bool bypass_spec_v1 = bpf_bypass_spec_v1(); u64 array_size, mask64; struct bpf_array *array; diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index 63b4dc495125..e8e910395bf6 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -260,15 +260,9 @@ bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) BTF_SET_START(sleepable_lsm_hooks) BTF_ID(func, bpf_lsm_bpf) BTF_ID(func, bpf_lsm_bpf_map) -BTF_ID(func, bpf_lsm_bpf_map_create) -BTF_ID(func, bpf_lsm_bpf_map_free) +BTF_ID(func, bpf_lsm_bpf_map_alloc_security) +BTF_ID(func, bpf_lsm_bpf_map_free_security) BTF_ID(func, bpf_lsm_bpf_prog) -BTF_ID(func, bpf_lsm_bpf_prog_load) -BTF_ID(func, bpf_lsm_bpf_prog_free) -BTF_ID(func, bpf_lsm_bpf_token_create) -BTF_ID(func, bpf_lsm_bpf_token_free) -BTF_ID(func, bpf_lsm_bpf_token_cmd) -BTF_ID(func, bpf_lsm_bpf_token_capable) BTF_ID(func, bpf_lsm_bprm_check_security) BTF_ID(func, bpf_lsm_bprm_committed_creds) BTF_ID(func, bpf_lsm_bprm_committing_creds) @@ -363,8 +357,9 @@ BTF_ID(func, bpf_lsm_userns_create) BTF_SET_END(sleepable_lsm_hooks) BTF_SET_START(untrusted_lsm_hooks) -BTF_ID(func, bpf_lsm_bpf_map_free) -BTF_ID(func, bpf_lsm_bpf_prog_free) +BTF_ID(func, bpf_lsm_bpf_map_free_security) +BTF_ID(func, bpf_lsm_bpf_prog_alloc_security) +BTF_ID(func, bpf_lsm_bpf_prog_free_security) BTF_ID(func, bpf_lsm_file_alloc_security) BTF_ID(func, bpf_lsm_file_free_security) #ifdef CONFIG_SECURITY_NETWORK diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c index 98e0e3835b28..491d20038cbe 100644 --- a/kernel/bpf/cgroup.c +++ b/kernel/bpf/cgroup.c @@ -1630,7 +1630,7 @@ cgroup_dev_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_perf_event_output: return &bpf_event_output_data_proto; default: - return bpf_base_func_proto(func_id, prog); + return bpf_base_func_proto(func_id); } } @@ -2191,7 +2191,7 @@ sysctl_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_perf_event_output: return &bpf_event_output_data_proto; default: - return bpf_base_func_proto(func_id, prog); + return bpf_base_func_proto(func_id); } } @@ -2348,7 +2348,7 @@ cg_sockopt_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_perf_event_output: return &bpf_event_output_data_proto; default: - return bpf_base_func_proto(func_id, prog); + return bpf_base_func_proto(func_id); } } diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 14ace23d517b..ea6843be2616 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -682,7 +682,7 @@ static bool bpf_prog_kallsyms_candidate(const struct bpf_prog *fp) void bpf_prog_kallsyms_add(struct bpf_prog *fp) { if (!bpf_prog_kallsyms_candidate(fp) || - !bpf_token_capable(fp->aux->token, CAP_BPF)) + !bpf_capable()) return; bpf_prog_ksym_set_addr(fp); @@ -2779,7 +2779,6 @@ void bpf_prog_free(struct bpf_prog *fp) if (aux->dst_prog) bpf_prog_put(aux->dst_prog); - bpf_token_put(aux->token); INIT_WORK(&aux->work, bpf_prog_free_deferred); schedule_work(&aux->work); } diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 07fd4b5704f3..be72824f32b2 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -1679,7 +1679,7 @@ const struct bpf_func_proto bpf_probe_read_kernel_str_proto __weak; const struct bpf_func_proto bpf_task_pt_regs_proto __weak; const struct bpf_func_proto * -bpf_base_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) +bpf_base_func_proto(enum bpf_func_id func_id) { switch (func_id) { case BPF_FUNC_map_lookup_elem: @@ -1730,7 +1730,7 @@ bpf_base_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) break; } - if (!bpf_token_capable(prog->aux->token, CAP_BPF)) + if (!bpf_capable()) return NULL; switch (func_id) { @@ -1788,7 +1788,7 @@ bpf_base_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) break; } - if (!bpf_token_capable(prog->aux->token, CAP_PERFMON)) + if (!perfmon_capable()) return NULL; switch (func_id) { diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c index 4383b3d13a55..1aafb2ff2e95 100644 --- a/kernel/bpf/inode.c +++ b/kernel/bpf/inode.c @@ -20,7 +20,6 @@ #include #include #include -#include #include "preload/bpf_preload.h" enum bpf_type { @@ -99,9 +98,9 @@ static const struct inode_operations bpf_prog_iops = { }; static const struct inode_operations bpf_map_iops = { }; static const struct inode_operations bpf_link_iops = { }; -struct inode *bpf_get_inode(struct super_block *sb, - const struct inode *dir, - umode_t mode) +static struct inode *bpf_get_inode(struct super_block *sb, + const struct inode *dir, + umode_t mode) { struct inode *inode; @@ -595,183 +594,15 @@ struct bpf_prog *bpf_prog_get_type_path(const char *name, enum bpf_prog_type typ } EXPORT_SYMBOL(bpf_prog_get_type_path); -struct bpffs_btf_enums { - const struct btf *btf; - const struct btf_type *cmd_t; - const struct btf_type *map_t; - const struct btf_type *prog_t; - const struct btf_type *attach_t; -}; - -static int find_bpffs_btf_enums(struct bpffs_btf_enums *info) -{ - const struct btf *btf; - const struct btf_type *t; - const char *name; - int i, n; - - memset(info, 0, sizeof(*info)); - - btf = bpf_get_btf_vmlinux(); - if (IS_ERR(btf)) - return PTR_ERR(btf); - if (!btf) - return -ENOENT; - - info->btf = btf; - - for (i = 1, n = btf_nr_types(btf); i < n; i++) { - t = btf_type_by_id(btf, i); - if (!btf_type_is_enum(t)) - continue; - - name = btf_name_by_offset(btf, t->name_off); - if (!name) - continue; - - if (strcmp(name, "bpf_cmd") == 0) - info->cmd_t = t; - else if (strcmp(name, "bpf_map_type") == 0) - info->map_t = t; - else if (strcmp(name, "bpf_prog_type") == 0) - info->prog_t = t; - else if (strcmp(name, "bpf_attach_type") == 0) - info->attach_t = t; - else - continue; - - if (info->cmd_t && info->map_t && info->prog_t && info->attach_t) - return 0; - } - - return -ESRCH; -} - -static bool find_btf_enum_const(const struct btf *btf, const struct btf_type *enum_t, - const char *prefix, const char *str, int *value) -{ - const struct btf_enum *e; - const char *name; - int i, n, pfx_len = strlen(prefix); - - *value = 0; - - if (!btf || !enum_t) - return false; - - for (i = 0, n = btf_vlen(enum_t); i < n; i++) { - e = &btf_enum(enum_t)[i]; - - name = btf_name_by_offset(btf, e->name_off); - if (!name || strncasecmp(name, prefix, pfx_len) != 0) - continue; - - /* match symbolic name case insensitive and ignoring prefix */ - if (strcasecmp(name + pfx_len, str) == 0) { - *value = e->val; - return true; - } - } - - return false; -} - -static void seq_print_delegate_opts(struct seq_file *m, - const char *opt_name, - const struct btf *btf, - const struct btf_type *enum_t, - const char *prefix, - u64 delegate_msk, u64 any_msk) -{ - const struct btf_enum *e; - bool first = true; - const char *name; - u64 msk; - int i, n, pfx_len = strlen(prefix); - - delegate_msk &= any_msk; /* clear unknown bits */ - - if (delegate_msk == 0) - return; - - seq_printf(m, ",%s", opt_name); - if (delegate_msk == any_msk) { - seq_printf(m, "=any"); - return; - } - - if (btf && enum_t) { - for (i = 0, n = btf_vlen(enum_t); i < n; i++) { - e = &btf_enum(enum_t)[i]; - name = btf_name_by_offset(btf, e->name_off); - if (!name || strncasecmp(name, prefix, pfx_len) != 0) - continue; - msk = 1ULL << e->val; - if (delegate_msk & msk) { - /* emit lower-case name without prefix */ - seq_printf(m, "%c", first ? '=' : ':'); - name += pfx_len; - while (*name) { - seq_printf(m, "%c", tolower(*name)); - name++; - } - - delegate_msk &= ~msk; - first = false; - } - } - } - if (delegate_msk) - seq_printf(m, "%c0x%llx", first ? '=' : ':', delegate_msk); -} - /* * Display the mount options in /proc/mounts. */ static int bpf_show_options(struct seq_file *m, struct dentry *root) { - struct bpf_mount_opts *opts = root->d_sb->s_fs_info; - struct inode *inode = d_inode(root); - umode_t mode = inode->i_mode & S_IALLUGO & ~S_ISVTX; - u64 mask; - - if (!uid_eq(inode->i_uid, GLOBAL_ROOT_UID)) - seq_printf(m, ",uid=%u", - from_kuid_munged(&init_user_ns, inode->i_uid)); - if (!gid_eq(inode->i_gid, GLOBAL_ROOT_GID)) - seq_printf(m, ",gid=%u", - from_kgid_munged(&init_user_ns, inode->i_gid)); + umode_t mode = d_inode(root)->i_mode & S_IALLUGO & ~S_ISVTX; + if (mode != S_IRWXUGO) seq_printf(m, ",mode=%o", mode); - - if (opts->delegate_cmds || opts->delegate_maps || - opts->delegate_progs || opts->delegate_attachs) { - struct bpffs_btf_enums info; - - /* ignore errors, fallback to hex */ - (void)find_bpffs_btf_enums(&info); - - mask = (1ULL << __MAX_BPF_CMD) - 1; - seq_print_delegate_opts(m, "delegate_cmds", - info.btf, info.cmd_t, "BPF_", - opts->delegate_cmds, mask); - - mask = (1ULL << __MAX_BPF_MAP_TYPE) - 1; - seq_print_delegate_opts(m, "delegate_maps", - info.btf, info.map_t, "BPF_MAP_TYPE_", - opts->delegate_maps, mask); - - mask = (1ULL << __MAX_BPF_PROG_TYPE) - 1; - seq_print_delegate_opts(m, "delegate_progs", - info.btf, info.prog_t, "BPF_PROG_TYPE_", - opts->delegate_progs, mask); - - mask = (1ULL << __MAX_BPF_ATTACH_TYPE) - 1; - seq_print_delegate_opts(m, "delegate_attachs", - info.btf, info.attach_t, "BPF_", - opts->delegate_attachs, mask); - } - return 0; } @@ -786,7 +617,7 @@ static void bpf_free_inode(struct inode *inode) free_inode_nonrcu(inode); } -const struct super_operations bpf_super_ops = { +static const struct super_operations bpf_super_ops = { .statfs = simple_statfs, .drop_inode = generic_delete_inode, .show_options = bpf_show_options, @@ -794,33 +625,23 @@ const struct super_operations bpf_super_ops = { }; enum { - OPT_UID, - OPT_GID, OPT_MODE, - OPT_DELEGATE_CMDS, - OPT_DELEGATE_MAPS, - OPT_DELEGATE_PROGS, - OPT_DELEGATE_ATTACHS, }; static const struct fs_parameter_spec bpf_fs_parameters[] = { - fsparam_u32 ("uid", OPT_UID), - fsparam_u32 ("gid", OPT_GID), fsparam_u32oct ("mode", OPT_MODE), - fsparam_string ("delegate_cmds", OPT_DELEGATE_CMDS), - fsparam_string ("delegate_maps", OPT_DELEGATE_MAPS), - fsparam_string ("delegate_progs", OPT_DELEGATE_PROGS), - fsparam_string ("delegate_attachs", OPT_DELEGATE_ATTACHS), {} }; +struct bpf_mount_opts { + umode_t mode; +}; + static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param) { - struct bpf_mount_opts *opts = fc->s_fs_info; + struct bpf_mount_opts *opts = fc->fs_private; struct fs_parse_result result; - kuid_t uid; - kgid_t gid; - int opt, err; + int opt; opt = fs_parse(fc, bpf_fs_parameters, param, &result); if (opt < 0) { @@ -841,104 +662,12 @@ static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param) } switch (opt) { - case OPT_UID: - uid = make_kuid(current_user_ns(), result.uint_32); - if (!uid_valid(uid)) - goto bad_value; - - /* - * The requested uid must be representable in the - * filesystem's idmapping. - */ - if (!kuid_has_mapping(fc->user_ns, uid)) - goto bad_value; - - opts->uid = uid; - break; - case OPT_GID: - gid = make_kgid(current_user_ns(), result.uint_32); - if (!gid_valid(gid)) - goto bad_value; - - /* - * The requested gid must be representable in the - * filesystem's idmapping. - */ - if (!kgid_has_mapping(fc->user_ns, gid)) - goto bad_value; - - opts->gid = gid; - break; case OPT_MODE: opts->mode = result.uint_32 & S_IALLUGO; break; - case OPT_DELEGATE_CMDS: - case OPT_DELEGATE_MAPS: - case OPT_DELEGATE_PROGS: - case OPT_DELEGATE_ATTACHS: { - struct bpffs_btf_enums info; - const struct btf_type *enum_t; - const char *enum_pfx; - u64 *delegate_msk, msk = 0; - char *p; - int val; - - /* ignore errors, fallback to hex */ - (void)find_bpffs_btf_enums(&info); - - switch (opt) { - case OPT_DELEGATE_CMDS: - delegate_msk = &opts->delegate_cmds; - enum_t = info.cmd_t; - enum_pfx = "BPF_"; - break; - case OPT_DELEGATE_MAPS: - delegate_msk = &opts->delegate_maps; - enum_t = info.map_t; - enum_pfx = "BPF_MAP_TYPE_"; - break; - case OPT_DELEGATE_PROGS: - delegate_msk = &opts->delegate_progs; - enum_t = info.prog_t; - enum_pfx = "BPF_PROG_TYPE_"; - break; - case OPT_DELEGATE_ATTACHS: - delegate_msk = &opts->delegate_attachs; - enum_t = info.attach_t; - enum_pfx = "BPF_"; - break; - default: - return -EINVAL; - } - - while ((p = strsep(¶m->string, ":"))) { - if (strcmp(p, "any") == 0) { - msk |= ~0ULL; - } else if (find_btf_enum_const(info.btf, enum_t, enum_pfx, p, &val)) { - msk |= 1ULL << val; - } else { - err = kstrtou64(p, 0, &msk); - if (err) - return err; - } - } - - /* Setting delegation mount options requires privileges */ - if (msk && !capable(CAP_SYS_ADMIN)) - return -EPERM; - - *delegate_msk |= msk; - break; - } - default: - /* ignore unknown mount options */ - break; } return 0; - -bad_value: - return invalfc(fc, "Bad value for '%s'", param->key); } struct bpf_preload_ops *bpf_preload_ops; @@ -1010,14 +739,10 @@ out: static int bpf_fill_super(struct super_block *sb, struct fs_context *fc) { static const struct tree_descr bpf_rfiles[] = { { "" } }; - struct bpf_mount_opts *opts = sb->s_fs_info; + struct bpf_mount_opts *opts = fc->fs_private; struct inode *inode; int ret; - /* Mounting an instance of BPF FS requires privileges */ - if (fc->user_ns != &init_user_ns && !capable(CAP_SYS_ADMIN)) - return -EPERM; - ret = simple_fill_super(sb, BPF_FS_MAGIC, bpf_rfiles); if (ret) return ret; @@ -1025,8 +750,6 @@ static int bpf_fill_super(struct super_block *sb, struct fs_context *fc) sb->s_op = &bpf_super_ops; inode = sb->s_root->d_inode; - inode->i_uid = opts->uid; - inode->i_gid = opts->gid; inode->i_op = &bpf_dir_iops; inode->i_mode &= ~S_IALLUGO; populate_bpffs(sb->s_root); @@ -1041,7 +764,7 @@ static int bpf_get_tree(struct fs_context *fc) static void bpf_free_fc(struct fs_context *fc) { - kfree(fc->s_fs_info); + kfree(fc->fs_private); } static const struct fs_context_operations bpf_context_ops = { @@ -1062,35 +785,18 @@ static int bpf_init_fs_context(struct fs_context *fc) return -ENOMEM; opts->mode = S_IRWXUGO; - opts->uid = current_fsuid(); - opts->gid = current_fsgid(); - - /* start out with no BPF token delegation enabled */ - opts->delegate_cmds = 0; - opts->delegate_maps = 0; - opts->delegate_progs = 0; - opts->delegate_attachs = 0; - fc->s_fs_info = opts; + fc->fs_private = opts; fc->ops = &bpf_context_ops; return 0; } -static void bpf_kill_super(struct super_block *sb) -{ - struct bpf_mount_opts *opts = sb->s_fs_info; - - kill_litter_super(sb); - kfree(opts); -} - static struct file_system_type bpf_fs_type = { .owner = THIS_MODULE, .name = "bpf", .init_fs_context = bpf_init_fs_context, .parameters = bpf_fs_parameters, - .kill_sb = bpf_kill_super, - .fs_flags = FS_USERNS_MOUNT, + .kill_sb = kill_litter_super, }; static int __init bpf_init(void) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 8faa1a20edf8..1bf9805ee185 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1011,8 +1011,8 @@ int map_check_no_btf(const struct bpf_map *map, return -ENOTSUPP; } -static int map_check_btf(struct bpf_map *map, struct bpf_token *token, - const struct btf *btf, u32 btf_key_id, u32 btf_value_id) +static int map_check_btf(struct bpf_map *map, const struct btf *btf, + u32 btf_key_id, u32 btf_value_id) { const struct btf_type *key_type, *value_type; u32 key_size, value_size; @@ -1040,7 +1040,7 @@ static int map_check_btf(struct bpf_map *map, struct bpf_token *token, if (!IS_ERR_OR_NULL(map->record)) { int i; - if (!bpf_token_capable(token, CAP_BPF)) { + if (!bpf_capable()) { ret = -EPERM; goto free_map_tab; } @@ -1123,17 +1123,11 @@ free_map_tab: return ret; } -static bool bpf_net_capable(void) -{ - return capable(CAP_NET_ADMIN) || capable(CAP_SYS_ADMIN); -} - -#define BPF_MAP_CREATE_LAST_FIELD map_token_fd +#define BPF_MAP_CREATE_LAST_FIELD map_extra /* called via syscall */ static int map_create(union bpf_attr *attr) { const struct bpf_map_ops *ops; - struct bpf_token *token = NULL; int numa_node = bpf_map_attr_numa_node(attr); u32 map_type = attr->map_type; struct bpf_map *map; @@ -1184,32 +1178,14 @@ static int map_create(union bpf_attr *attr) if (!ops->map_mem_usage) return -EINVAL; - if (attr->map_token_fd) { - token = bpf_token_get_from_fd(attr->map_token_fd); - if (IS_ERR(token)) - return PTR_ERR(token); - - /* if current token doesn't grant map creation permissions, - * then we can't use this token, so ignore it and rely on - * system-wide capabilities checks - */ - if (!bpf_token_allow_cmd(token, BPF_MAP_CREATE) || - !bpf_token_allow_map_type(token, attr->map_type)) { - bpf_token_put(token); - token = NULL; - } - } - - err = -EPERM; - /* Intent here is for unprivileged_bpf_disabled to block BPF map * creation for unprivileged users; other actions depend * on fd availability and access to bpffs, so are dependent on * object creation success. Even with unprivileged BPF disabled, * capability checks are still carried out. */ - if (sysctl_unprivileged_bpf_disabled && !bpf_token_capable(token, CAP_BPF)) - goto put_token; + if (sysctl_unprivileged_bpf_disabled && !bpf_capable()) + return -EPERM; /* check privileged map type permissions */ switch (map_type) { @@ -1242,27 +1218,25 @@ static int map_create(union bpf_attr *attr) case BPF_MAP_TYPE_LRU_PERCPU_HASH: case BPF_MAP_TYPE_STRUCT_OPS: case BPF_MAP_TYPE_CPUMAP: - if (!bpf_token_capable(token, CAP_BPF)) - goto put_token; + if (!bpf_capable()) + return -EPERM; break; case BPF_MAP_TYPE_SOCKMAP: case BPF_MAP_TYPE_SOCKHASH: case BPF_MAP_TYPE_DEVMAP: case BPF_MAP_TYPE_DEVMAP_HASH: case BPF_MAP_TYPE_XSKMAP: - if (!bpf_token_capable(token, CAP_NET_ADMIN)) - goto put_token; + if (!capable(CAP_NET_ADMIN)) + return -EPERM; break; default: WARN(1, "unsupported map type %d", map_type); - goto put_token; + return -EPERM; } map = ops->map_alloc(attr); - if (IS_ERR(map)) { - err = PTR_ERR(map); - goto put_token; - } + if (IS_ERR(map)) + return PTR_ERR(map); map->ops = ops; map->map_type = map_type; @@ -1299,7 +1273,7 @@ static int map_create(union bpf_attr *attr) map->btf = btf; if (attr->btf_value_type_id) { - err = map_check_btf(map, token, btf, attr->btf_key_type_id, + err = map_check_btf(map, btf, attr->btf_key_type_id, attr->btf_value_type_id); if (err) goto free_map; @@ -1311,16 +1285,15 @@ static int map_create(union bpf_attr *attr) attr->btf_vmlinux_value_type_id; } - err = security_bpf_map_create(map, attr, token); + err = security_bpf_map_alloc(map); if (err) - goto free_map_sec; + goto free_map; err = bpf_map_alloc_id(map); if (err) goto free_map_sec; bpf_map_save_memcg(map); - bpf_token_put(token); err = bpf_map_new_fd(map, f_flags); if (err < 0) { @@ -1341,8 +1314,6 @@ free_map_sec: free_map: btf_put(map->btf); map->ops->map_free(map); -put_token: - bpf_token_put(token); return err; } @@ -2173,7 +2144,7 @@ static void __bpf_prog_put_rcu(struct rcu_head *rcu) kvfree(aux->func_info); kfree(aux->func_info_aux); free_uid(aux->user); - security_bpf_prog_free(aux->prog); + security_bpf_prog_free(aux); bpf_prog_free(aux->prog); } @@ -2619,15 +2590,13 @@ static bool is_perfmon_prog_type(enum bpf_prog_type prog_type) } /* last field in 'union bpf_attr' used by this command */ -#define BPF_PROG_LOAD_LAST_FIELD prog_token_fd +#define BPF_PROG_LOAD_LAST_FIELD log_true_size static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) { enum bpf_prog_type type = attr->prog_type; struct bpf_prog *prog, *dst_prog = NULL; struct btf *attach_btf = NULL; - struct bpf_token *token = NULL; - bool bpf_cap; int err; char license[128]; @@ -2644,31 +2613,10 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) BPF_F_TEST_REG_INVARIANTS)) return -EINVAL; - bpf_prog_load_fixup_attach_type(attr); - - if (attr->prog_token_fd) { - token = bpf_token_get_from_fd(attr->prog_token_fd); - if (IS_ERR(token)) - return PTR_ERR(token); - /* if current token doesn't grant prog loading permissions, - * then we can't use this token, so ignore it and rely on - * system-wide capabilities checks - */ - if (!bpf_token_allow_cmd(token, BPF_PROG_LOAD) || - !bpf_token_allow_prog_type(token, attr->prog_type, - attr->expected_attach_type)) { - bpf_token_put(token); - token = NULL; - } - } - - bpf_cap = bpf_token_capable(token, CAP_BPF); - err = -EPERM; - if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && (attr->prog_flags & BPF_F_ANY_ALIGNMENT) && - !bpf_cap) - goto put_token; + !bpf_capable()) + return -EPERM; /* Intent here is for unprivileged_bpf_disabled to block BPF program * creation for unprivileged users; other actions depend @@ -2677,23 +2625,21 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) * capability checks are still carried out for these * and other operations. */ - if (sysctl_unprivileged_bpf_disabled && !bpf_cap) - goto put_token; + if (sysctl_unprivileged_bpf_disabled && !bpf_capable()) + return -EPERM; if (attr->insn_cnt == 0 || - attr->insn_cnt > (bpf_cap ? BPF_COMPLEXITY_LIMIT_INSNS : BPF_MAXINSNS)) { - err = -E2BIG; - goto put_token; - } + attr->insn_cnt > (bpf_capable() ? BPF_COMPLEXITY_LIMIT_INSNS : BPF_MAXINSNS)) + return -E2BIG; if (type != BPF_PROG_TYPE_SOCKET_FILTER && type != BPF_PROG_TYPE_CGROUP_SKB && - !bpf_cap) - goto put_token; + !bpf_capable()) + return -EPERM; - if (is_net_admin_prog_type(type) && !bpf_token_capable(token, CAP_NET_ADMIN)) - goto put_token; - if (is_perfmon_prog_type(type) && !bpf_token_capable(token, CAP_PERFMON)) - goto put_token; + if (is_net_admin_prog_type(type) && !capable(CAP_NET_ADMIN) && !capable(CAP_SYS_ADMIN)) + return -EPERM; + if (is_perfmon_prog_type(type) && !perfmon_capable()) + return -EPERM; /* attach_prog_fd/attach_btf_obj_fd can specify fd of either bpf_prog * or btf, we need to check which one it is @@ -2703,33 +2649,27 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) if (IS_ERR(dst_prog)) { dst_prog = NULL; attach_btf = btf_get_by_fd(attr->attach_btf_obj_fd); - if (IS_ERR(attach_btf)) { - err = -EINVAL; - goto put_token; - } + if (IS_ERR(attach_btf)) + return -EINVAL; if (!btf_is_kernel(attach_btf)) { /* attaching through specifying bpf_prog's BTF * objects directly might be supported eventually */ btf_put(attach_btf); - err = -ENOTSUPP; - goto put_token; + return -ENOTSUPP; } } } else if (attr->attach_btf_id) { /* fall back to vmlinux BTF, if BTF type ID is specified */ attach_btf = bpf_get_btf_vmlinux(); - if (IS_ERR(attach_btf)) { - err = PTR_ERR(attach_btf); - goto put_token; - } - if (!attach_btf) { - err = -EINVAL; - goto put_token; - } + if (IS_ERR(attach_btf)) + return PTR_ERR(attach_btf); + if (!attach_btf) + return -EINVAL; btf_get(attach_btf); } + bpf_prog_load_fixup_attach_type(attr); if (bpf_prog_load_check_attach(type, attr->expected_attach_type, attach_btf, attr->attach_btf_id, dst_prog)) { @@ -2737,8 +2677,7 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) bpf_prog_put(dst_prog); if (attach_btf) btf_put(attach_btf); - err = -EINVAL; - goto put_token; + return -EINVAL; } /* plain bpf_prog allocation */ @@ -2748,8 +2687,7 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) bpf_prog_put(dst_prog); if (attach_btf) btf_put(attach_btf); - err = -EINVAL; - goto put_token; + return -ENOMEM; } prog->expected_attach_type = attr->expected_attach_type; @@ -2760,9 +2698,9 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) prog->aux->sleepable = attr->prog_flags & BPF_F_SLEEPABLE; prog->aux->xdp_has_frags = attr->prog_flags & BPF_F_XDP_HAS_FRAGS; - /* move token into prog->aux, reuse taken refcnt */ - prog->aux->token = token; - token = NULL; + err = security_bpf_prog_alloc(prog->aux); + if (err) + goto free_prog; prog->aux->user = get_current_user(); prog->len = attr->insn_cnt; @@ -2771,12 +2709,12 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) if (copy_from_bpfptr(prog->insns, make_bpfptr(attr->insns, uattr.is_kernel), bpf_prog_insn_size(prog)) != 0) - goto free_prog; + goto free_prog_sec; /* copy eBPF program license from user space */ if (strncpy_from_bpfptr(license, make_bpfptr(attr->license, uattr.is_kernel), sizeof(license) - 1) < 0) - goto free_prog; + goto free_prog_sec; license[sizeof(license) - 1] = 0; /* eBPF programs must be GPL compatible to use GPL-ed functions */ @@ -2790,29 +2728,25 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) if (bpf_prog_is_dev_bound(prog->aux)) { err = bpf_prog_dev_bound_init(prog, attr); if (err) - goto free_prog; + goto free_prog_sec; } if (type == BPF_PROG_TYPE_EXT && dst_prog && bpf_prog_is_dev_bound(dst_prog->aux)) { err = bpf_prog_dev_bound_inherit(prog, dst_prog); if (err) - goto free_prog; + goto free_prog_sec; } /* find program type: socket_filter vs tracing_filter */ err = find_prog_type(type, prog); if (err < 0) - goto free_prog; + goto free_prog_sec; prog->aux->load_time = ktime_get_boottime_ns(); err = bpf_obj_name_cpy(prog->aux->name, attr->prog_name, sizeof(attr->prog_name)); if (err < 0) - goto free_prog; - - err = security_bpf_prog_load(prog, attr, token); - if (err) goto free_prog_sec; /* run eBPF verifier */ @@ -2858,16 +2792,13 @@ free_used_maps: */ __bpf_prog_put_noref(prog, prog->aux->real_func_cnt); return err; - free_prog_sec: - security_bpf_prog_free(prog); -free_prog: free_uid(prog->aux->user); + security_bpf_prog_free(prog->aux); +free_prog: if (prog->aux->attach_btf) btf_put(prog->aux->attach_btf); bpf_prog_free(prog); -put_token: - bpf_token_put(token); return err; } @@ -3857,7 +3788,7 @@ static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog, case BPF_PROG_TYPE_SK_LOOKUP: return attach_type == prog->expected_attach_type ? 0 : -EINVAL; case BPF_PROG_TYPE_CGROUP_SKB: - if (!bpf_token_capable(prog->aux->token, CAP_NET_ADMIN)) + if (!capable(CAP_NET_ADMIN)) /* cg-skb progs can be loaded by unpriv user. * check permissions at attach time. */ @@ -4060,7 +3991,7 @@ static int bpf_prog_detach(const union bpf_attr *attr) static int bpf_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr) { - if (!bpf_net_capable()) + if (!capable(CAP_NET_ADMIN)) return -EPERM; if (CHECK_ATTR(BPF_PROG_QUERY)) return -EINVAL; @@ -4828,31 +4759,15 @@ static int bpf_obj_get_info_by_fd(const union bpf_attr *attr, return err; } -#define BPF_BTF_LOAD_LAST_FIELD btf_token_fd +#define BPF_BTF_LOAD_LAST_FIELD btf_log_true_size static int bpf_btf_load(const union bpf_attr *attr, bpfptr_t uattr, __u32 uattr_size) { - struct bpf_token *token = NULL; - if (CHECK_ATTR(BPF_BTF_LOAD)) return -EINVAL; - if (attr->btf_token_fd) { - token = bpf_token_get_from_fd(attr->btf_token_fd); - if (IS_ERR(token)) - return PTR_ERR(token); - if (!bpf_token_allow_cmd(token, BPF_BTF_LOAD)) { - bpf_token_put(token); - token = NULL; - } - } - - if (!bpf_token_capable(token, CAP_BPF)) { - bpf_token_put(token); + if (!bpf_capable()) return -EPERM; - } - - bpf_token_put(token); return btf_new_fd(attr, uattr, uattr_size); } @@ -5470,20 +5385,6 @@ out_prog_put: return ret; } -#define BPF_TOKEN_CREATE_LAST_FIELD token_create.bpffs_fd - -static int token_create(union bpf_attr *attr) -{ - if (CHECK_ATTR(BPF_TOKEN_CREATE)) - return -EINVAL; - - /* no flags are supported yet */ - if (attr->token_create.flags) - return -EINVAL; - - return bpf_token_create(attr); -} - static int __sys_bpf(int cmd, bpfptr_t uattr, unsigned int size) { union bpf_attr attr; @@ -5617,9 +5518,6 @@ static int __sys_bpf(int cmd, bpfptr_t uattr, unsigned int size) case BPF_PROG_BIND_MAP: err = bpf_prog_bind_map(&attr); break; - case BPF_TOKEN_CREATE: - err = token_create(&attr); - break; default: err = -EINVAL; break; @@ -5726,7 +5624,7 @@ static const struct bpf_func_proto bpf_sys_bpf_proto = { const struct bpf_func_proto * __weak tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { - return bpf_base_func_proto(func_id, prog); + return bpf_base_func_proto(func_id); } BPF_CALL_1(bpf_sys_close, u32, fd) @@ -5776,8 +5674,7 @@ syscall_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { switch (func_id) { case BPF_FUNC_sys_bpf: - return !bpf_token_capable(prog->aux->token, CAP_PERFMON) - ? NULL : &bpf_sys_bpf_proto; + return !perfmon_capable() ? NULL : &bpf_sys_bpf_proto; case BPF_FUNC_btf_find_by_name_kind: return &bpf_btf_find_by_name_kind_proto; case BPF_FUNC_sys_close: diff --git a/kernel/bpf/token.c b/kernel/bpf/token.c deleted file mode 100644 index a86fccd57e2d..000000000000 --- a/kernel/bpf/token.c +++ /dev/null @@ -1,271 +0,0 @@ -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include - -bool bpf_token_capable(const struct bpf_token *token, int cap) -{ - /* BPF token allows ns_capable() level of capabilities, but only if - * token's userns is *exactly* the same as current user's userns - */ - if (token && current_user_ns() == token->userns) { - if (ns_capable(token->userns, cap) || - (cap != CAP_SYS_ADMIN && ns_capable(token->userns, CAP_SYS_ADMIN))) - return security_bpf_token_capable(token, cap) == 0; - } - /* otherwise fallback to capable() checks */ - return capable(cap) || (cap != CAP_SYS_ADMIN && capable(CAP_SYS_ADMIN)); -} - -void bpf_token_inc(struct bpf_token *token) -{ - atomic64_inc(&token->refcnt); -} - -static void bpf_token_free(struct bpf_token *token) -{ - security_bpf_token_free(token); - put_user_ns(token->userns); - kvfree(token); -} - -static void bpf_token_put_deferred(struct work_struct *work) -{ - struct bpf_token *token = container_of(work, struct bpf_token, work); - - bpf_token_free(token); -} - -void bpf_token_put(struct bpf_token *token) -{ - if (!token) - return; - - if (!atomic64_dec_and_test(&token->refcnt)) - return; - - INIT_WORK(&token->work, bpf_token_put_deferred); - schedule_work(&token->work); -} - -static int bpf_token_release(struct inode *inode, struct file *filp) -{ - struct bpf_token *token = filp->private_data; - - bpf_token_put(token); - return 0; -} - -static void bpf_token_show_fdinfo(struct seq_file *m, struct file *filp) -{ - struct bpf_token *token = filp->private_data; - u64 mask; - - BUILD_BUG_ON(__MAX_BPF_CMD >= 64); - mask = (1ULL << __MAX_BPF_CMD) - 1; - if ((token->allowed_cmds & mask) == mask) - seq_printf(m, "allowed_cmds:\tany\n"); - else - seq_printf(m, "allowed_cmds:\t0x%llx\n", token->allowed_cmds); - - BUILD_BUG_ON(__MAX_BPF_MAP_TYPE >= 64); - mask = (1ULL << __MAX_BPF_MAP_TYPE) - 1; - if ((token->allowed_maps & mask) == mask) - seq_printf(m, "allowed_maps:\tany\n"); - else - seq_printf(m, "allowed_maps:\t0x%llx\n", token->allowed_maps); - - BUILD_BUG_ON(__MAX_BPF_PROG_TYPE >= 64); - mask = (1ULL << __MAX_BPF_PROG_TYPE) - 1; - if ((token->allowed_progs & mask) == mask) - seq_printf(m, "allowed_progs:\tany\n"); - else - seq_printf(m, "allowed_progs:\t0x%llx\n", token->allowed_progs); - - BUILD_BUG_ON(__MAX_BPF_ATTACH_TYPE >= 64); - mask = (1ULL << __MAX_BPF_ATTACH_TYPE) - 1; - if ((token->allowed_attachs & mask) == mask) - seq_printf(m, "allowed_attachs:\tany\n"); - else - seq_printf(m, "allowed_attachs:\t0x%llx\n", token->allowed_attachs); -} - -#define BPF_TOKEN_INODE_NAME "bpf-token" - -static const struct inode_operations bpf_token_iops = { }; - -static const struct file_operations bpf_token_fops = { - .release = bpf_token_release, - .show_fdinfo = bpf_token_show_fdinfo, -}; - -int bpf_token_create(union bpf_attr *attr) -{ - struct bpf_mount_opts *mnt_opts; - struct bpf_token *token = NULL; - struct user_namespace *userns; - struct inode *inode; - struct file *file; - struct path path; - struct fd f; - umode_t mode; - int err, fd; - - f = fdget(attr->token_create.bpffs_fd); - if (!f.file) - return -EBADF; - - path = f.file->f_path; - path_get(&path); - fdput(f); - - if (path.dentry != path.mnt->mnt_sb->s_root) { - err = -EINVAL; - goto out_path; - } - if (path.mnt->mnt_sb->s_op != &bpf_super_ops) { - err = -EINVAL; - goto out_path; - } - err = path_permission(&path, MAY_ACCESS); - if (err) - goto out_path; - - userns = path.dentry->d_sb->s_user_ns; - /* - * Enforce that creators of BPF tokens are in the same user - * namespace as the BPF FS instance. This makes reasoning about - * permissions a lot easier and we can always relax this later. - */ - if (current_user_ns() != userns) { - err = -EPERM; - goto out_path; - } - if (!ns_capable(userns, CAP_BPF)) { - err = -EPERM; - goto out_path; - } - - mnt_opts = path.dentry->d_sb->s_fs_info; - if (mnt_opts->delegate_cmds == 0 && - mnt_opts->delegate_maps == 0 && - mnt_opts->delegate_progs == 0 && - mnt_opts->delegate_attachs == 0) { - err = -ENOENT; /* no BPF token delegation is set up */ - goto out_path; - } - - mode = S_IFREG | ((S_IRUSR | S_IWUSR) & ~current_umask()); - inode = bpf_get_inode(path.mnt->mnt_sb, NULL, mode); - if (IS_ERR(inode)) { - err = PTR_ERR(inode); - goto out_path; - } - - inode->i_op = &bpf_token_iops; - inode->i_fop = &bpf_token_fops; - clear_nlink(inode); /* make sure it is unlinked */ - - file = alloc_file_pseudo(inode, path.mnt, BPF_TOKEN_INODE_NAME, O_RDWR, &bpf_token_fops); - if (IS_ERR(file)) { - iput(inode); - err = PTR_ERR(file); - goto out_path; - } - - token = kvzalloc(sizeof(*token), GFP_USER); - if (!token) { - err = -ENOMEM; - goto out_file; - } - - atomic64_set(&token->refcnt, 1); - - /* remember bpffs owning userns for future ns_capable() checks */ - token->userns = get_user_ns(userns); - - token->allowed_cmds = mnt_opts->delegate_cmds; - token->allowed_maps = mnt_opts->delegate_maps; - token->allowed_progs = mnt_opts->delegate_progs; - token->allowed_attachs = mnt_opts->delegate_attachs; - - err = security_bpf_token_create(token, attr, &path); - if (err) - goto out_token; - - fd = get_unused_fd_flags(O_CLOEXEC); - if (fd < 0) { - err = fd; - goto out_token; - } - - file->private_data = token; - fd_install(fd, file); - - path_put(&path); - return fd; - -out_token: - bpf_token_free(token); -out_file: - fput(file); -out_path: - path_put(&path); - return err; -} - -struct bpf_token *bpf_token_get_from_fd(u32 ufd) -{ - struct fd f = fdget(ufd); - struct bpf_token *token; - - if (!f.file) - return ERR_PTR(-EBADF); - if (f.file->f_op != &bpf_token_fops) { - fdput(f); - return ERR_PTR(-EINVAL); - } - - token = f.file->private_data; - bpf_token_inc(token); - fdput(f); - - return token; -} - -bool bpf_token_allow_cmd(const struct bpf_token *token, enum bpf_cmd cmd) -{ - /* BPF token can be used only within exactly the same userns in which - * it was created - */ - if (!token || current_user_ns() != token->userns) - return false; - if (!(token->allowed_cmds & (1ULL << cmd))) - return false; - return security_bpf_token_cmd(token, cmd) == 0; -} - -bool bpf_token_allow_map_type(const struct bpf_token *token, enum bpf_map_type type) -{ - if (!token || type >= __MAX_BPF_MAP_TYPE) - return false; - - return token->allowed_maps & (1ULL << type); -} - -bool bpf_token_allow_prog_type(const struct bpf_token *token, - enum bpf_prog_type prog_type, - enum bpf_attach_type attach_type) -{ - if (!token || prog_type >= __MAX_BPF_PROG_TYPE || attach_type >= __MAX_BPF_ATTACH_TYPE) - return false; - - return (token->allowed_progs & (1ULL << prog_type)) && - (token->allowed_attachs & (1ULL << attach_type)); -} diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9456ee0ad129..4ceec8c2a484 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -20594,12 +20594,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u3 env->prog = *prog; env->ops = bpf_verifier_ops[env->prog->type]; env->fd_array = make_bpfptr(attr->fd_array, uattr.is_kernel); - - env->allow_ptr_leaks = bpf_allow_ptr_leaks(env->prog->aux->token); - env->allow_uninit_stack = bpf_allow_uninit_stack(env->prog->aux->token); - env->bypass_spec_v1 = bpf_bypass_spec_v1(env->prog->aux->token); - env->bypass_spec_v4 = bpf_bypass_spec_v4(env->prog->aux->token); - env->bpf_capable = is_priv = bpf_token_capable(env->prog->aux->token, CAP_BPF); + is_priv = bpf_capable(); bpf_get_btf_vmlinux(); @@ -20631,6 +20626,12 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u3 if (attr->prog_flags & BPF_F_ANY_ALIGNMENT) env->strict_alignment = false; + env->allow_ptr_leaks = bpf_allow_ptr_leaks(); + env->allow_uninit_stack = bpf_allow_uninit_stack(); + env->bypass_spec_v1 = bpf_bypass_spec_v1(); + env->bypass_spec_v4 = bpf_bypass_spec_v4(); + env->bpf_capable = bpf_capable(); + if (is_priv) env->test_state_freq = attr->prog_flags & BPF_F_TEST_STATE_FREQ; env->test_reg_invariants = attr->prog_flags & BPF_F_TEST_REG_INVARIANTS; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 492d60e9c480..7ac6c52b25eb 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1629,7 +1629,7 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_trace_vprintk: return bpf_get_trace_vprintk_proto(); default: - return bpf_base_func_proto(func_id, prog); + return bpf_base_func_proto(func_id); } } diff --git a/net/core/filter.c b/net/core/filter.c index 3cc52b82bab8..24061f29c9dd 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -87,7 +87,7 @@ #include "dev.h" static const struct bpf_func_proto * -bpf_sk_base_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog); +bpf_sk_base_func_proto(enum bpf_func_id func_id); int copy_bpf_fprog_from_user(struct sock_fprog *dst, sockptr_t src, int len) { @@ -7862,7 +7862,7 @@ sock_filter_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_ktime_get_coarse_ns: return &bpf_ktime_get_coarse_ns_proto; default: - return bpf_base_func_proto(func_id, prog); + return bpf_base_func_proto(func_id); } } @@ -7955,7 +7955,7 @@ sock_addr_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return NULL; } default: - return bpf_sk_base_func_proto(func_id, prog); + return bpf_sk_base_func_proto(func_id); } } @@ -7974,7 +7974,7 @@ sk_filter_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_perf_event_output: return &bpf_skb_event_output_proto; default: - return bpf_sk_base_func_proto(func_id, prog); + return bpf_sk_base_func_proto(func_id); } } @@ -8161,7 +8161,7 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) #endif #endif default: - return bpf_sk_base_func_proto(func_id, prog); + return bpf_sk_base_func_proto(func_id); } } @@ -8220,7 +8220,7 @@ xdp_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) #endif #endif default: - return bpf_sk_base_func_proto(func_id, prog); + return bpf_sk_base_func_proto(func_id); } #if IS_MODULE(CONFIG_NF_CONNTRACK) && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES) @@ -8281,7 +8281,7 @@ sock_ops_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_tcp_sock_proto; #endif /* CONFIG_INET */ default: - return bpf_sk_base_func_proto(func_id, prog); + return bpf_sk_base_func_proto(func_id); } } @@ -8323,7 +8323,7 @@ sk_msg_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_get_cgroup_classid_curr_proto; #endif default: - return bpf_sk_base_func_proto(func_id, prog); + return bpf_sk_base_func_proto(func_id); } } @@ -8367,7 +8367,7 @@ sk_skb_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_skc_lookup_tcp_proto; #endif default: - return bpf_sk_base_func_proto(func_id, prog); + return bpf_sk_base_func_proto(func_id); } } @@ -8378,7 +8378,7 @@ flow_dissector_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_skb_load_bytes: return &bpf_flow_dissector_load_bytes_proto; default: - return bpf_sk_base_func_proto(func_id, prog); + return bpf_sk_base_func_proto(func_id); } } @@ -8405,7 +8405,7 @@ lwt_out_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_skb_under_cgroup: return &bpf_skb_under_cgroup_proto; default: - return bpf_sk_base_func_proto(func_id, prog); + return bpf_sk_base_func_proto(func_id); } } @@ -8580,7 +8580,7 @@ static bool cg_skb_is_valid_access(int off, int size, return false; case bpf_ctx_range(struct __sk_buff, data): case bpf_ctx_range(struct __sk_buff, data_end): - if (!bpf_token_capable(prog->aux->token, CAP_BPF)) + if (!bpf_capable()) return false; break; } @@ -8592,7 +8592,7 @@ static bool cg_skb_is_valid_access(int off, int size, case bpf_ctx_range_till(struct __sk_buff, cb[0], cb[4]): break; case bpf_ctx_range(struct __sk_buff, tstamp): - if (!bpf_token_capable(prog->aux->token, CAP_BPF)) + if (!bpf_capable()) return false; break; default: @@ -11236,7 +11236,7 @@ sk_reuseport_func_proto(enum bpf_func_id func_id, case BPF_FUNC_ktime_get_coarse_ns: return &bpf_ktime_get_coarse_ns_proto; default: - return bpf_base_func_proto(func_id, prog); + return bpf_base_func_proto(func_id); } } @@ -11418,7 +11418,7 @@ sk_lookup_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_sk_release: return &bpf_sk_release_proto; default: - return bpf_sk_base_func_proto(func_id, prog); + return bpf_sk_base_func_proto(func_id); } } @@ -11752,7 +11752,7 @@ const struct bpf_func_proto bpf_sock_from_file_proto = { }; static const struct bpf_func_proto * -bpf_sk_base_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) +bpf_sk_base_func_proto(enum bpf_func_id func_id) { const struct bpf_func_proto *func; @@ -11781,10 +11781,10 @@ bpf_sk_base_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_ktime_get_coarse_ns: return &bpf_ktime_get_coarse_ns_proto; default: - return bpf_base_func_proto(func_id, prog); + return bpf_base_func_proto(func_id); } - if (!bpf_token_capable(prog->aux->token, CAP_PERFMON)) + if (!perfmon_capable()) return NULL; return func; diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c index 634cfafa583d..ae8b15e6896f 100644 --- a/net/ipv4/bpf_tcp_ca.c +++ b/net/ipv4/bpf_tcp_ca.c @@ -191,7 +191,7 @@ bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id, case BPF_FUNC_ktime_get_coarse_ns: return &bpf_ktime_get_coarse_ns_proto; default: - return bpf_base_func_proto(func_id, prog); + return bpf_base_func_proto(func_id); } } diff --git a/net/netfilter/nf_bpf_link.c b/net/netfilter/nf_bpf_link.c index 5257d5e7eb09..0e4beae421f8 100644 --- a/net/netfilter/nf_bpf_link.c +++ b/net/netfilter/nf_bpf_link.c @@ -314,7 +314,7 @@ static bool nf_is_valid_access(int off, int size, enum bpf_access_type type, static const struct bpf_func_proto * bpf_nf_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { - return bpf_base_func_proto(func_id, prog); + return bpf_base_func_proto(func_id); } const struct bpf_verifier_ops netfilter_verifier_ops = { diff --git a/security/security.c b/security/security.c index 088a79c35c26..dcb3e7014f9b 100644 --- a/security/security.c +++ b/security/security.c @@ -5167,87 +5167,29 @@ int security_bpf_prog(struct bpf_prog *prog) } /** - * security_bpf_map_create() - Check if BPF map creation is allowed - * @map: BPF map object - * @attr: BPF syscall attributes used to create BPF map - * @token: BPF token used to grant user access - * - * Do a check when the kernel creates a new BPF map. This is also the - * point where LSM blob is allocated for LSMs that need them. - * - * Return: Returns 0 on success, error on failure. - */ -int security_bpf_map_create(struct bpf_map *map, union bpf_attr *attr, - struct bpf_token *token) -{ - return call_int_hook(bpf_map_create, 0, map, attr, token); -} - -/** - * security_bpf_prog_load() - Check if loading of BPF program is allowed - * @prog: BPF program object - * @attr: BPF syscall attributes used to create BPF program - * @token: BPF token used to grant user access to BPF subsystem - * - * Perform an access control check when the kernel loads a BPF program and - * allocates associated BPF program object. This hook is also responsible for - * allocating any required LSM state for the BPF program. - * - * Return: Returns 0 on success, error on failure. - */ -int security_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, - struct bpf_token *token) -{ - return call_int_hook(bpf_prog_load, 0, prog, attr, token); -} - -/** - * security_bpf_token_create() - Check if creating of BPF token is allowed - * @token: BPF token object - * @attr: BPF syscall attributes used to create BPF token - * @path: path pointing to BPF FS mount point from which BPF token is created - * - * Do a check when the kernel instantiates a new BPF token object from BPF FS - * instance. This is also the point where LSM blob can be allocated for LSMs. - * - * Return: Returns 0 on success, error on failure. - */ -int security_bpf_token_create(struct bpf_token *token, union bpf_attr *attr, - struct path *path) -{ - return call_int_hook(bpf_token_create, 0, token, attr, path); -} - -/** - * security_bpf_token_cmd() - Check if BPF token is allowed to delegate - * requested BPF syscall command - * @token: BPF token object - * @cmd: BPF syscall command requested to be delegated by BPF token + * security_bpf_map_alloc() - Allocate a bpf map LSM blob + * @map: bpf map * - * Do a check when the kernel decides whether provided BPF token should allow - * delegation of requested BPF syscall command. + * Initialize the security field inside bpf map. * * Return: Returns 0 on success, error on failure. */ -int security_bpf_token_cmd(const struct bpf_token *token, enum bpf_cmd cmd) +int security_bpf_map_alloc(struct bpf_map *map) { - return call_int_hook(bpf_token_cmd, 0, token, cmd); + return call_int_hook(bpf_map_alloc_security, 0, map); } /** - * security_bpf_token_capable() - Check if BPF token is allowed to delegate - * requested BPF-related capability - * @token: BPF token object - * @cap: capabilities requested to be delegated by BPF token + * security_bpf_prog_alloc() - Allocate a bpf program LSM blob + * @aux: bpf program aux info struct * - * Do a check when the kernel decides whether provided BPF token should allow - * delegation of requested BPF-related capabilities. + * Initialize the security field inside bpf program. * * Return: Returns 0 on success, error on failure. */ -int security_bpf_token_capable(const struct bpf_token *token, int cap) +int security_bpf_prog_alloc(struct bpf_prog_aux *aux) { - return call_int_hook(bpf_token_capable, 0, token, cap); + return call_int_hook(bpf_prog_alloc_security, 0, aux); } /** @@ -5258,29 +5200,18 @@ int security_bpf_token_capable(const struct bpf_token *token, int cap) */ void security_bpf_map_free(struct bpf_map *map) { - call_void_hook(bpf_map_free, map); -} - -/** - * security_bpf_prog_free() - Free a BPF program's LSM blob - * @prog: BPF program struct - * - * Clean up the security information stored inside BPF program. - */ -void security_bpf_prog_free(struct bpf_prog *prog) -{ - call_void_hook(bpf_prog_free, prog); + call_void_hook(bpf_map_free_security, map); } /** - * security_bpf_token_free() - Free a BPF token's LSM blob - * @token: BPF token struct + * security_bpf_prog_free() - Free a bpf program's LSM blob + * @aux: bpf program aux info struct * - * Clean up the security information stored inside BPF token. + * Clean up the security information stored inside bpf prog. */ -void security_bpf_token_free(struct bpf_token *token) +void security_bpf_prog_free(struct bpf_prog_aux *aux) { - call_void_hook(bpf_token_free, token); + call_void_hook(bpf_prog_free_security, aux); } #endif /* CONFIG_BPF_SYSCALL */ diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 1501e95366a1..feda711c6b7b 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -6783,8 +6783,7 @@ static int selinux_bpf_prog(struct bpf_prog *prog) BPF__PROG_RUN, NULL); } -static int selinux_bpf_map_create(struct bpf_map *map, union bpf_attr *attr, - struct bpf_token *token) +static int selinux_bpf_map_alloc(struct bpf_map *map) { struct bpf_security_struct *bpfsec; @@ -6806,8 +6805,7 @@ static void selinux_bpf_map_free(struct bpf_map *map) kfree(bpfsec); } -static int selinux_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, - struct bpf_token *token) +static int selinux_bpf_prog_alloc(struct bpf_prog_aux *aux) { struct bpf_security_struct *bpfsec; @@ -6816,39 +6814,16 @@ static int selinux_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, return -ENOMEM; bpfsec->sid = current_sid(); - prog->aux->security = bpfsec; + aux->security = bpfsec; return 0; } -static void selinux_bpf_prog_free(struct bpf_prog *prog) +static void selinux_bpf_prog_free(struct bpf_prog_aux *aux) { - struct bpf_security_struct *bpfsec = prog->aux->security; + struct bpf_security_struct *bpfsec = aux->security; - prog->aux->security = NULL; - kfree(bpfsec); -} - -static int selinux_bpf_token_create(struct bpf_token *token, union bpf_attr *attr, - struct path *path) -{ - struct bpf_security_struct *bpfsec; - - bpfsec = kzalloc(sizeof(*bpfsec), GFP_KERNEL); - if (!bpfsec) - return -ENOMEM; - - bpfsec->sid = current_sid(); - token->security = bpfsec; - - return 0; -} - -static void selinux_bpf_token_free(struct bpf_token *token) -{ - struct bpf_security_struct *bpfsec = token->security; - - token->security = NULL; + aux->security = NULL; kfree(bpfsec); } #endif @@ -7204,9 +7179,8 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = { LSM_HOOK_INIT(bpf, selinux_bpf), LSM_HOOK_INIT(bpf_map, selinux_bpf_map), LSM_HOOK_INIT(bpf_prog, selinux_bpf_prog), - LSM_HOOK_INIT(bpf_map_free, selinux_bpf_map_free), - LSM_HOOK_INIT(bpf_prog_free, selinux_bpf_prog_free), - LSM_HOOK_INIT(bpf_token_free, selinux_bpf_token_free), + LSM_HOOK_INIT(bpf_map_free_security, selinux_bpf_map_free), + LSM_HOOK_INIT(bpf_prog_free_security, selinux_bpf_prog_free), #endif #ifdef CONFIG_PERF_EVENTS @@ -7263,9 +7237,8 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = { LSM_HOOK_INIT(audit_rule_init, selinux_audit_rule_init), #endif #ifdef CONFIG_BPF_SYSCALL - LSM_HOOK_INIT(bpf_map_create, selinux_bpf_map_create), - LSM_HOOK_INIT(bpf_prog_load, selinux_bpf_prog_load), - LSM_HOOK_INIT(bpf_token_create, selinux_bpf_token_create), + LSM_HOOK_INIT(bpf_map_alloc_security, selinux_bpf_map_alloc), + LSM_HOOK_INIT(bpf_prog_alloc_security, selinux_bpf_prog_alloc), #endif #ifdef CONFIG_PERF_EVENTS LSM_HOOK_INIT(perf_event_alloc, selinux_perf_event_alloc), diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index e0545201b55f..7f24d898efbb 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -847,36 +847,6 @@ union bpf_iter_link_info { * Returns zero on success. On error, -1 is returned and *errno* * is set appropriately. * - * BPF_TOKEN_CREATE - * Description - * Create BPF token with embedded information about what - * BPF-related functionality it allows: - * - a set of allowed bpf() syscall commands; - * - a set of allowed BPF map types to be created with - * BPF_MAP_CREATE command, if BPF_MAP_CREATE itself is allowed; - * - a set of allowed BPF program types and BPF program attach - * types to be loaded with BPF_PROG_LOAD command, if - * BPF_PROG_LOAD itself is allowed. - * - * BPF token is created (derived) from an instance of BPF FS, - * assuming it has necessary delegation mount options specified. - * This BPF token can be passed as an extra parameter to various - * bpf() syscall commands to grant BPF subsystem functionality to - * unprivileged processes. - * - * When created, BPF token is "associated" with the owning - * user namespace of BPF FS instance (super block) that it was - * derived from, and subsequent BPF operations performed with - * BPF token would be performing capabilities checks (i.e., - * CAP_BPF, CAP_PERFMON, CAP_NET_ADMIN, CAP_SYS_ADMIN) within - * that user namespace. Without BPF token, such capabilities - * have to be granted in init user namespace, making bpf() - * syscall incompatible with user namespace, for the most part. - * - * Return - * A new file descriptor (a nonnegative integer), or -1 if an - * error occurred (in which case, *errno* is set appropriately). - * * NOTES * eBPF objects (maps and programs) can be shared between processes. * @@ -931,8 +901,6 @@ enum bpf_cmd { BPF_ITER_CREATE, BPF_LINK_DETACH, BPF_PROG_BIND_MAP, - BPF_TOKEN_CREATE, - __MAX_BPF_CMD, }; enum bpf_map_type { @@ -983,7 +951,6 @@ enum bpf_map_type { BPF_MAP_TYPE_BLOOM_FILTER, BPF_MAP_TYPE_USER_RINGBUF, BPF_MAP_TYPE_CGRP_STORAGE, - __MAX_BPF_MAP_TYPE }; /* Note that tracing related programs such as @@ -1028,7 +995,6 @@ enum bpf_prog_type { BPF_PROG_TYPE_SK_LOOKUP, BPF_PROG_TYPE_SYSCALL, /* a program that can execute syscalls */ BPF_PROG_TYPE_NETFILTER, - __MAX_BPF_PROG_TYPE }; enum bpf_attach_type { @@ -1437,7 +1403,6 @@ union bpf_attr { * to using 5 hash functions). */ __u64 map_extra; - __u32 map_token_fd; }; struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */ @@ -1507,7 +1472,6 @@ union bpf_attr { * truncated), or smaller (if log buffer wasn't filled completely). */ __u32 log_true_size; - __u32 prog_token_fd; }; struct { /* anonymous struct used by BPF_OBJ_* commands */ @@ -1620,7 +1584,6 @@ union bpf_attr { * truncated), or smaller (if log buffer wasn't filled completely). */ __u32 btf_log_true_size; - __u32 btf_token_fd; }; struct { @@ -1751,11 +1714,6 @@ union bpf_attr { __u32 flags; /* extra flags */ } prog_bind_map; - struct { /* struct used by BPF_TOKEN_CREATE command */ - __u32 flags; - __u32 bpffs_fd; - } token_create; - } __attribute__((aligned(8))); /* The description below is an attempt at providing documentation to eBPF diff --git a/tools/lib/bpf/Build b/tools/lib/bpf/Build index b6619199a706..2d0c282c8588 100644 --- a/tools/lib/bpf/Build +++ b/tools/lib/bpf/Build @@ -1,4 +1,4 @@ libbpf-y := libbpf.o bpf.o nlattr.o btf.o libbpf_errno.o str_error.o \ netlink.o bpf_prog_linfo.o libbpf_probes.o hashmap.o \ btf_dump.o ringbuf.o strset.o linker.o gen_loader.o relo_core.o \ - usdt.o zip.o elf.o features.o + usdt.o zip.o elf.o diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c index 0ad8e532b3cf..9dc9625651dc 100644 --- a/tools/lib/bpf/bpf.c +++ b/tools/lib/bpf/bpf.c @@ -103,7 +103,7 @@ int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts) * [0] https://lore.kernel.org/bpf/20201201215900.3569844-1-guro@fb.com/ * [1] d05512618056 ("bpf: Add bpf_ktime_get_coarse_ns helper") */ -int probe_memcg_account(int token_fd) +int probe_memcg_account(void) { const size_t attr_sz = offsetofend(union bpf_attr, attach_btf_obj_fd); struct bpf_insn insns[] = { @@ -120,7 +120,6 @@ int probe_memcg_account(int token_fd) attr.insns = ptr_to_u64(insns); attr.insn_cnt = insn_cnt; attr.license = ptr_to_u64("GPL"); - attr.prog_token_fd = token_fd; prog_fd = sys_bpf_fd(BPF_PROG_LOAD, &attr, attr_sz); if (prog_fd >= 0) { @@ -147,7 +146,7 @@ int bump_rlimit_memlock(void) struct rlimit rlim; /* if kernel supports memcg-based accounting, skip bumping RLIMIT_MEMLOCK */ - if (memlock_bumped || feat_supported(NULL, FEAT_MEMCG_ACCOUNT)) + if (memlock_bumped || kernel_supports(NULL, FEAT_MEMCG_ACCOUNT)) return 0; memlock_bumped = true; @@ -170,7 +169,7 @@ int bpf_map_create(enum bpf_map_type map_type, __u32 max_entries, const struct bpf_map_create_opts *opts) { - const size_t attr_sz = offsetofend(union bpf_attr, map_token_fd); + const size_t attr_sz = offsetofend(union bpf_attr, map_extra); union bpf_attr attr; int fd; @@ -182,7 +181,7 @@ int bpf_map_create(enum bpf_map_type map_type, return libbpf_err(-EINVAL); attr.map_type = map_type; - if (map_name && feat_supported(NULL, FEAT_PROG_NAME)) + if (map_name && kernel_supports(NULL, FEAT_PROG_NAME)) libbpf_strlcpy(attr.map_name, map_name, sizeof(attr.map_name)); attr.key_size = key_size; attr.value_size = value_size; @@ -199,8 +198,6 @@ int bpf_map_create(enum bpf_map_type map_type, attr.numa_node = OPTS_GET(opts, numa_node, 0); attr.map_ifindex = OPTS_GET(opts, map_ifindex, 0); - attr.map_token_fd = OPTS_GET(opts, token_fd, 0); - fd = sys_bpf_fd(BPF_MAP_CREATE, &attr, attr_sz); return libbpf_err_errno(fd); } @@ -235,7 +232,7 @@ int bpf_prog_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns, size_t insn_cnt, struct bpf_prog_load_opts *opts) { - const size_t attr_sz = offsetofend(union bpf_attr, prog_token_fd); + const size_t attr_sz = offsetofend(union bpf_attr, log_true_size); void *finfo = NULL, *linfo = NULL; const char *func_info, *line_info; __u32 log_size, log_level, attach_prog_fd, attach_btf_obj_fd; @@ -264,9 +261,8 @@ int bpf_prog_load(enum bpf_prog_type prog_type, attr.prog_flags = OPTS_GET(opts, prog_flags, 0); attr.prog_ifindex = OPTS_GET(opts, prog_ifindex, 0); attr.kern_version = OPTS_GET(opts, kern_version, 0); - attr.prog_token_fd = OPTS_GET(opts, token_fd, 0); - if (prog_name && feat_supported(NULL, FEAT_PROG_NAME)) + if (prog_name && kernel_supports(NULL, FEAT_PROG_NAME)) libbpf_strlcpy(attr.prog_name, prog_name, sizeof(attr.prog_name)); attr.license = ptr_to_u64(license); @@ -1186,7 +1182,7 @@ int bpf_raw_tracepoint_open(const char *name, int prog_fd) int bpf_btf_load(const void *btf_data, size_t btf_size, struct bpf_btf_load_opts *opts) { - const size_t attr_sz = offsetofend(union bpf_attr, btf_token_fd); + const size_t attr_sz = offsetofend(union bpf_attr, btf_log_true_size); union bpf_attr attr; char *log_buf; size_t log_size; @@ -1211,8 +1207,6 @@ int bpf_btf_load(const void *btf_data, size_t btf_size, struct bpf_btf_load_opts attr.btf = ptr_to_u64(btf_data); attr.btf_size = btf_size; - attr.btf_token_fd = OPTS_GET(opts, token_fd, 0); - /* log_level == 0 and log_buf != NULL means "try loading without * log_buf, but retry with log_buf and log_level=1 on error", which is * consistent across low-level and high-level BTF and program loading @@ -1293,20 +1287,3 @@ int bpf_prog_bind_map(int prog_fd, int map_fd, ret = sys_bpf(BPF_PROG_BIND_MAP, &attr, attr_sz); return libbpf_err_errno(ret); } - -int bpf_token_create(int bpffs_fd, struct bpf_token_create_opts *opts) -{ - const size_t attr_sz = offsetofend(union bpf_attr, token_create); - union bpf_attr attr; - int fd; - - if (!OPTS_VALID(opts, bpf_token_create_opts)) - return libbpf_err(-EINVAL); - - memset(&attr, 0, attr_sz); - attr.token_create.bpffs_fd = bpffs_fd; - attr.token_create.flags = OPTS_GET(opts, flags, 0); - - fd = sys_bpf_fd(BPF_TOKEN_CREATE, &attr, attr_sz); - return libbpf_err_errno(fd); -} diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h index 991b86bfe7e4..d0f53772bdc0 100644 --- a/tools/lib/bpf/bpf.h +++ b/tools/lib/bpf/bpf.h @@ -51,11 +51,8 @@ struct bpf_map_create_opts { __u32 numa_node; __u32 map_ifindex; - - __u32 token_fd; - size_t :0; }; -#define bpf_map_create_opts__last_field token_fd +#define bpf_map_create_opts__last_field map_ifindex LIBBPF_API int bpf_map_create(enum bpf_map_type map_type, const char *map_name, @@ -105,10 +102,9 @@ struct bpf_prog_load_opts { * If kernel doesn't support this feature, log_size is left unchanged. */ __u32 log_true_size; - __u32 token_fd; size_t :0; }; -#define bpf_prog_load_opts__last_field token_fd +#define bpf_prog_load_opts__last_field log_true_size LIBBPF_API int bpf_prog_load(enum bpf_prog_type prog_type, const char *prog_name, const char *license, @@ -134,10 +130,9 @@ struct bpf_btf_load_opts { * If kernel doesn't support this feature, log_size is left unchanged. */ __u32 log_true_size; - __u32 token_fd; size_t :0; }; -#define bpf_btf_load_opts__last_field token_fd +#define bpf_btf_load_opts__last_field log_true_size LIBBPF_API int bpf_btf_load(const void *btf_data, size_t btf_size, struct bpf_btf_load_opts *opts); @@ -645,30 +640,6 @@ struct bpf_test_run_opts { LIBBPF_API int bpf_prog_test_run_opts(int prog_fd, struct bpf_test_run_opts *opts); -struct bpf_token_create_opts { - size_t sz; /* size of this struct for forward/backward compatibility */ - __u32 flags; - size_t :0; -}; -#define bpf_token_create_opts__last_field flags - -/** - * @brief **bpf_token_create()** creates a new instance of BPF token derived - * from specified BPF FS mount point. - * - * BPF token created with this API can be passed to bpf() syscall for - * commands like BPF_PROG_LOAD, BPF_MAP_CREATE, etc. - * - * @param bpffs_fd FD for BPF FS instance from which to derive a BPF token - * instance. - * @param opts optional BPF token creation options, can be NULL - * - * @return BPF token FD > 0, on success; negative error code, otherwise (errno - * is also set to the error code) - */ -LIBBPF_API int bpf_token_create(int bpffs_fd, - struct bpf_token_create_opts *opts); - #ifdef __cplusplus } /* extern "C" */ #endif diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 63033c334320..ee95fd379d4d 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -1317,9 +1317,7 @@ struct btf *btf__parse_split(const char *path, struct btf *base_btf) static void *btf_get_raw_data(const struct btf *btf, __u32 *size, bool swap_endian); -int btf_load_into_kernel(struct btf *btf, - char *log_buf, size_t log_sz, __u32 log_level, - int token_fd) +int btf_load_into_kernel(struct btf *btf, char *log_buf, size_t log_sz, __u32 log_level) { LIBBPF_OPTS(bpf_btf_load_opts, opts); __u32 buf_sz = 0, raw_size; @@ -1369,7 +1367,6 @@ retry_load: opts.log_level = log_level; } - opts.token_fd = token_fd; btf->fd = bpf_btf_load(raw_data, raw_size, &opts); if (btf->fd < 0) { /* time to turn on verbose mode and try again */ @@ -1397,7 +1394,7 @@ done: int btf__load_into_kernel(struct btf *btf) { - return btf_load_into_kernel(btf, NULL, 0, 0, 0); + return btf_load_into_kernel(btf, NULL, 0, 0); } int btf__fd(const struct btf *btf) diff --git a/tools/lib/bpf/elf.c b/tools/lib/bpf/elf.c index c92e02394159..b02faec748a5 100644 --- a/tools/lib/bpf/elf.c +++ b/tools/lib/bpf/elf.c @@ -11,6 +11,8 @@ #include "libbpf_internal.h" #include "str_error.h" +#define STRERR_BUFSIZE 128 + /* A SHT_GNU_versym section holds 16-bit words. This bit is set if * the symbol is hidden and can only be seen when referenced using an * explicit version number. This is a GNU extension. diff --git a/tools/lib/bpf/features.c b/tools/lib/bpf/features.c deleted file mode 100644 index ce98a334be21..000000000000 --- a/tools/lib/bpf/features.c +++ /dev/null @@ -1,478 +0,0 @@ -// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) -/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */ -#include -#include -#include "bpf.h" -#include "libbpf.h" -#include "libbpf_common.h" -#include "libbpf_internal.h" -#include "str_error.h" - -static inline __u64 ptr_to_u64(const void *ptr) -{ - return (__u64)(unsigned long)ptr; -} - -static int probe_fd(int fd) -{ - if (fd >= 0) - close(fd); - return fd >= 0; -} - -static int probe_kern_prog_name(int token_fd) -{ - const size_t attr_sz = offsetofend(union bpf_attr, prog_name); - struct bpf_insn insns[] = { - BPF_MOV64_IMM(BPF_REG_0, 0), - BPF_EXIT_INSN(), - }; - union bpf_attr attr; - int ret; - - memset(&attr, 0, attr_sz); - attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER; - attr.license = ptr_to_u64("GPL"); - attr.insns = ptr_to_u64(insns); - attr.insn_cnt = (__u32)ARRAY_SIZE(insns); - attr.prog_token_fd = token_fd; - libbpf_strlcpy(attr.prog_name, "libbpf_nametest", sizeof(attr.prog_name)); - - /* make sure loading with name works */ - ret = sys_bpf_prog_load(&attr, attr_sz, PROG_LOAD_ATTEMPTS); - return probe_fd(ret); -} - -static int probe_kern_global_data(int token_fd) -{ - char *cp, errmsg[STRERR_BUFSIZE]; - struct bpf_insn insns[] = { - BPF_LD_MAP_VALUE(BPF_REG_1, 0, 16), - BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 42), - BPF_MOV64_IMM(BPF_REG_0, 0), - BPF_EXIT_INSN(), - }; - LIBBPF_OPTS(bpf_map_create_opts, map_opts, .token_fd = token_fd); - LIBBPF_OPTS(bpf_prog_load_opts, prog_opts, .token_fd = token_fd); - int ret, map, insn_cnt = ARRAY_SIZE(insns); - - map = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_global", sizeof(int), 32, 1, &map_opts); - if (map < 0) { - ret = -errno; - cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg)); - pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n", - __func__, cp, -ret); - return ret; - } - - insns[0].imm = map; - - ret = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, &prog_opts); - close(map); - return probe_fd(ret); -} - -static int probe_kern_btf(int token_fd) -{ - static const char strs[] = "\0int"; - __u32 types[] = { - /* int */ - BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), - }; - - return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), - strs, sizeof(strs), token_fd)); -} - -static int probe_kern_btf_func(int token_fd) -{ - static const char strs[] = "\0int\0x\0a"; - /* void x(int a) {} */ - __u32 types[] = { - /* int */ - BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ - /* FUNC_PROTO */ /* [2] */ - BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0), - BTF_PARAM_ENC(7, 1), - /* FUNC x */ /* [3] */ - BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0), 2), - }; - - return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), - strs, sizeof(strs), token_fd)); -} - -static int probe_kern_btf_func_global(int token_fd) -{ - static const char strs[] = "\0int\0x\0a"; - /* static void x(int a) {} */ - __u32 types[] = { - /* int */ - BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ - /* FUNC_PROTO */ /* [2] */ - BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0), - BTF_PARAM_ENC(7, 1), - /* FUNC x BTF_FUNC_GLOBAL */ /* [3] */ - BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, BTF_FUNC_GLOBAL), 2), - }; - - return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), - strs, sizeof(strs), token_fd)); -} - -static int probe_kern_btf_datasec(int token_fd) -{ - static const char strs[] = "\0x\0.data"; - /* static int a; */ - __u32 types[] = { - /* int */ - BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ - /* VAR x */ /* [2] */ - BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1), - BTF_VAR_STATIC, - /* DATASEC val */ /* [3] */ - BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4), - BTF_VAR_SECINFO_ENC(2, 0, 4), - }; - - return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), - strs, sizeof(strs), token_fd)); -} - -static int probe_kern_btf_float(int token_fd) -{ - static const char strs[] = "\0float"; - __u32 types[] = { - /* float */ - BTF_TYPE_FLOAT_ENC(1, 4), - }; - - return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), - strs, sizeof(strs), token_fd)); -} - -static int probe_kern_btf_decl_tag(int token_fd) -{ - static const char strs[] = "\0tag"; - __u32 types[] = { - /* int */ - BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ - /* VAR x */ /* [2] */ - BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1), - BTF_VAR_STATIC, - /* attr */ - BTF_TYPE_DECL_TAG_ENC(1, 2, -1), - }; - - return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), - strs, sizeof(strs), token_fd)); -} - -static int probe_kern_btf_type_tag(int token_fd) -{ - static const char strs[] = "\0tag"; - __u32 types[] = { - /* int */ - BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ - /* attr */ - BTF_TYPE_TYPE_TAG_ENC(1, 1), /* [2] */ - /* ptr */ - BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 2), /* [3] */ - }; - - return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), - strs, sizeof(strs), token_fd)); -} - -static int probe_kern_array_mmap(int token_fd) -{ - LIBBPF_OPTS(bpf_map_create_opts, opts, - .map_flags = BPF_F_MMAPABLE, - .token_fd = token_fd, - ); - int fd; - - fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_mmap", sizeof(int), sizeof(int), 1, &opts); - return probe_fd(fd); -} - -static int probe_kern_exp_attach_type(int token_fd) -{ - LIBBPF_OPTS(bpf_prog_load_opts, opts, - .expected_attach_type = BPF_CGROUP_INET_SOCK_CREATE, - .token_fd = token_fd, - ); - struct bpf_insn insns[] = { - BPF_MOV64_IMM(BPF_REG_0, 0), - BPF_EXIT_INSN(), - }; - int fd, insn_cnt = ARRAY_SIZE(insns); - - /* use any valid combination of program type and (optional) - * non-zero expected attach type (i.e., not a BPF_CGROUP_INET_INGRESS) - * to see if kernel supports expected_attach_type field for - * BPF_PROG_LOAD command - */ - fd = bpf_prog_load(BPF_PROG_TYPE_CGROUP_SOCK, NULL, "GPL", insns, insn_cnt, &opts); - return probe_fd(fd); -} - -static int probe_kern_probe_read_kernel(int token_fd) -{ - LIBBPF_OPTS(bpf_prog_load_opts, opts, .token_fd = token_fd); - struct bpf_insn insns[] = { - BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), /* r1 = r10 (fp) */ - BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8), /* r1 += -8 */ - BPF_MOV64_IMM(BPF_REG_2, 8), /* r2 = 8 */ - BPF_MOV64_IMM(BPF_REG_3, 0), /* r3 = 0 */ - BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_probe_read_kernel), - BPF_EXIT_INSN(), - }; - int fd, insn_cnt = ARRAY_SIZE(insns); - - fd = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", insns, insn_cnt, &opts); - return probe_fd(fd); -} - -static int probe_prog_bind_map(int token_fd) -{ - char *cp, errmsg[STRERR_BUFSIZE]; - struct bpf_insn insns[] = { - BPF_MOV64_IMM(BPF_REG_0, 0), - BPF_EXIT_INSN(), - }; - LIBBPF_OPTS(bpf_map_create_opts, map_opts, .token_fd = token_fd); - LIBBPF_OPTS(bpf_prog_load_opts, prog_opts, .token_fd = token_fd); - int ret, map, prog, insn_cnt = ARRAY_SIZE(insns); - - map = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_det_bind", sizeof(int), 32, 1, &map_opts); - if (map < 0) { - ret = -errno; - cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg)); - pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n", - __func__, cp, -ret); - return ret; - } - - prog = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, &prog_opts); - if (prog < 0) { - close(map); - return 0; - } - - ret = bpf_prog_bind_map(prog, map, NULL); - - close(map); - close(prog); - - return ret >= 0; -} - -static int probe_module_btf(int token_fd) -{ - static const char strs[] = "\0int"; - __u32 types[] = { - /* int */ - BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), - }; - struct bpf_btf_info info; - __u32 len = sizeof(info); - char name[16]; - int fd, err; - - fd = libbpf__load_raw_btf((char *)types, sizeof(types), strs, sizeof(strs), token_fd); - if (fd < 0) - return 0; /* BTF not supported at all */ - - memset(&info, 0, sizeof(info)); - info.name = ptr_to_u64(name); - info.name_len = sizeof(name); - - /* check that BPF_OBJ_GET_INFO_BY_FD supports specifying name pointer; - * kernel's module BTF support coincides with support for - * name/name_len fields in struct bpf_btf_info. - */ - err = bpf_btf_get_info_by_fd(fd, &info, &len); - close(fd); - return !err; -} - -static int probe_perf_link(int token_fd) -{ - struct bpf_insn insns[] = { - BPF_MOV64_IMM(BPF_REG_0, 0), - BPF_EXIT_INSN(), - }; - LIBBPF_OPTS(bpf_prog_load_opts, opts, .token_fd = token_fd); - int prog_fd, link_fd, err; - - prog_fd = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", - insns, ARRAY_SIZE(insns), &opts); - if (prog_fd < 0) - return -errno; - - /* use invalid perf_event FD to get EBADF, if link is supported; - * otherwise EINVAL should be returned - */ - link_fd = bpf_link_create(prog_fd, -1, BPF_PERF_EVENT, NULL); - err = -errno; /* close() can clobber errno */ - - if (link_fd >= 0) - close(link_fd); - close(prog_fd); - - return link_fd < 0 && err == -EBADF; -} - -static int probe_uprobe_multi_link(int token_fd) -{ - LIBBPF_OPTS(bpf_prog_load_opts, load_opts, - .expected_attach_type = BPF_TRACE_UPROBE_MULTI, - .token_fd = token_fd, - ); - LIBBPF_OPTS(bpf_link_create_opts, link_opts); - struct bpf_insn insns[] = { - BPF_MOV64_IMM(BPF_REG_0, 0), - BPF_EXIT_INSN(), - }; - int prog_fd, link_fd, err; - unsigned long offset = 0; - - prog_fd = bpf_prog_load(BPF_PROG_TYPE_KPROBE, NULL, "GPL", - insns, ARRAY_SIZE(insns), &load_opts); - if (prog_fd < 0) - return -errno; - - /* Creating uprobe in '/' binary should fail with -EBADF. */ - link_opts.uprobe_multi.path = "/"; - link_opts.uprobe_multi.offsets = &offset; - link_opts.uprobe_multi.cnt = 1; - - link_fd = bpf_link_create(prog_fd, -1, BPF_TRACE_UPROBE_MULTI, &link_opts); - err = -errno; /* close() can clobber errno */ - - if (link_fd >= 0) - close(link_fd); - close(prog_fd); - - return link_fd < 0 && err == -EBADF; -} - -static int probe_kern_bpf_cookie(int token_fd) -{ - struct bpf_insn insns[] = { - BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_get_attach_cookie), - BPF_EXIT_INSN(), - }; - LIBBPF_OPTS(bpf_prog_load_opts, opts, .token_fd = token_fd); - int ret, insn_cnt = ARRAY_SIZE(insns); - - ret = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", insns, insn_cnt, &opts); - return probe_fd(ret); -} - -static int probe_kern_btf_enum64(int token_fd) -{ - static const char strs[] = "\0enum64"; - __u32 types[] = { - BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_ENUM64, 0, 0), 8), - }; - - return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), - strs, sizeof(strs), token_fd)); -} - -typedef int (*feature_probe_fn)(int /* token_fd */); - -static struct kern_feature_cache feature_cache; - -static struct kern_feature_desc { - const char *desc; - feature_probe_fn probe; -} feature_probes[__FEAT_CNT] = { - [FEAT_PROG_NAME] = { - "BPF program name", probe_kern_prog_name, - }, - [FEAT_GLOBAL_DATA] = { - "global variables", probe_kern_global_data, - }, - [FEAT_BTF] = { - "minimal BTF", probe_kern_btf, - }, - [FEAT_BTF_FUNC] = { - "BTF functions", probe_kern_btf_func, - }, - [FEAT_BTF_GLOBAL_FUNC] = { - "BTF global function", probe_kern_btf_func_global, - }, - [FEAT_BTF_DATASEC] = { - "BTF data section and variable", probe_kern_btf_datasec, - }, - [FEAT_ARRAY_MMAP] = { - "ARRAY map mmap()", probe_kern_array_mmap, - }, - [FEAT_EXP_ATTACH_TYPE] = { - "BPF_PROG_LOAD expected_attach_type attribute", - probe_kern_exp_attach_type, - }, - [FEAT_PROBE_READ_KERN] = { - "bpf_probe_read_kernel() helper", probe_kern_probe_read_kernel, - }, - [FEAT_PROG_BIND_MAP] = { - "BPF_PROG_BIND_MAP support", probe_prog_bind_map, - }, - [FEAT_MODULE_BTF] = { - "module BTF support", probe_module_btf, - }, - [FEAT_BTF_FLOAT] = { - "BTF_KIND_FLOAT support", probe_kern_btf_float, - }, - [FEAT_PERF_LINK] = { - "BPF perf link support", probe_perf_link, - }, - [FEAT_BTF_DECL_TAG] = { - "BTF_KIND_DECL_TAG support", probe_kern_btf_decl_tag, - }, - [FEAT_BTF_TYPE_TAG] = { - "BTF_KIND_TYPE_TAG support", probe_kern_btf_type_tag, - }, - [FEAT_MEMCG_ACCOUNT] = { - "memcg-based memory accounting", probe_memcg_account, - }, - [FEAT_BPF_COOKIE] = { - "BPF cookie support", probe_kern_bpf_cookie, - }, - [FEAT_BTF_ENUM64] = { - "BTF_KIND_ENUM64 support", probe_kern_btf_enum64, - }, - [FEAT_SYSCALL_WRAPPER] = { - "Kernel using syscall wrapper", probe_kern_syscall_wrapper, - }, - [FEAT_UPROBE_MULTI_LINK] = { - "BPF multi-uprobe link support", probe_uprobe_multi_link, - }, -}; - -bool feat_supported(struct kern_feature_cache *cache, enum kern_feature_id feat_id) -{ - struct kern_feature_desc *feat = &feature_probes[feat_id]; - int ret; - - /* assume global feature cache, unless custom one is provided */ - if (!cache) - cache = &feature_cache; - - if (READ_ONCE(cache->res[feat_id]) == FEAT_UNKNOWN) { - ret = feat->probe(cache->token_fd); - if (ret > 0) { - WRITE_ONCE(cache->res[feat_id], FEAT_SUPPORTED); - } else if (ret == 0) { - WRITE_ONCE(cache->res[feat_id], FEAT_MISSING); - } else { - pr_warn("Detection of kernel %s support failed: %d\n", feat->desc, ret); - WRITE_ONCE(cache->res[feat_id], FEAT_MISSING); - } - } - - return READ_ONCE(cache->res[feat_id]) == FEAT_SUPPORTED; -} diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 4b5ff9508e18..ac54ebc0629f 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -59,8 +59,6 @@ #define BPF_FS_MAGIC 0xcafe4a11 #endif -#define BPF_FS_DEFAULT_PATH "/sys/fs/bpf" - #define BPF_INSN_SZ (sizeof(struct bpf_insn)) /* vsprintf() in __base_pr() uses nonliteral format string. It may break @@ -695,10 +693,6 @@ struct bpf_object { struct usdt_manager *usdt_man; - struct kern_feature_cache *feat_cache; - char *token_path; - int token_fd; - char path[]; }; @@ -2198,7 +2192,7 @@ static int build_map_pin_path(struct bpf_map *map, const char *path) int err; if (!path) - path = BPF_FS_DEFAULT_PATH; + path = "/sys/fs/bpf"; err = pathname_concat(buf, sizeof(buf), path, bpf_map__name(map)); if (err) @@ -3285,7 +3279,7 @@ skip_exception_cb: } else { /* currently BPF_BTF_LOAD only supports log_level 1 */ err = btf_load_into_kernel(kern_btf, obj->log_buf, obj->log_size, - obj->log_level ? 1 : 0, obj->token_fd); + obj->log_level ? 1 : 0); } if (sanitize) { if (!err) { @@ -4608,63 +4602,6 @@ int bpf_map__set_max_entries(struct bpf_map *map, __u32 max_entries) return 0; } -static int bpf_object_prepare_token(struct bpf_object *obj) -{ - const char *bpffs_path; - int bpffs_fd = -1, token_fd, err; - bool mandatory; - enum libbpf_print_level level; - - /* token is already set up */ - if (obj->token_fd > 0) - return 0; - /* token is explicitly prevented */ - if (obj->token_fd < 0) { - pr_debug("object '%s': token is prevented, skipping...\n", obj->name); - /* reset to zero to avoid extra checks during map_create and prog_load steps */ - obj->token_fd = 0; - return 0; - } - - mandatory = obj->token_path != NULL; - level = mandatory ? LIBBPF_WARN : LIBBPF_DEBUG; - - bpffs_path = obj->token_path ?: BPF_FS_DEFAULT_PATH; - bpffs_fd = open(bpffs_path, O_DIRECTORY, O_RDWR); - if (bpffs_fd < 0) { - err = -errno; - __pr(level, "object '%s': failed (%d) to open BPF FS mount at '%s'%s\n", - obj->name, err, bpffs_path, - mandatory ? "" : ", skipping optional step..."); - return mandatory ? err : 0; - } - - token_fd = bpf_token_create(bpffs_fd, 0); - close(bpffs_fd); - if (token_fd < 0) { - if (!mandatory && token_fd == -ENOENT) { - pr_debug("object '%s': BPF FS at '%s' doesn't have BPF token delegation set up, skipping...\n", - obj->name, bpffs_path); - return 0; - } - __pr(level, "object '%s': failed (%d) to create BPF token from '%s'%s\n", - obj->name, token_fd, bpffs_path, - mandatory ? "" : ", skipping optional step..."); - return mandatory ? token_fd : 0; - } - - obj->feat_cache = calloc(1, sizeof(*obj->feat_cache)); - if (!obj->feat_cache) { - close(token_fd); - return -ENOMEM; - } - - obj->token_fd = token_fd; - obj->feat_cache->token_fd = token_fd; - - return 0; -} - static int bpf_object__probe_loading(struct bpf_object *obj) { @@ -4674,7 +4611,6 @@ bpf_object__probe_loading(struct bpf_object *obj) BPF_EXIT_INSN(), }; int ret, insn_cnt = ARRAY_SIZE(insns); - LIBBPF_OPTS(bpf_prog_load_opts, opts, .token_fd = obj->token_fd); if (obj->gen_loader) return 0; @@ -4684,9 +4620,9 @@ bpf_object__probe_loading(struct bpf_object *obj) pr_warn("Failed to bump RLIMIT_MEMLOCK (err = %d), you might need to do it explicitly!\n", ret); /* make sure basic loading works */ - ret = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, &opts); + ret = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, NULL); if (ret < 0) - ret = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", insns, insn_cnt, &opts); + ret = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", insns, insn_cnt, NULL); if (ret < 0) { ret = errno; cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg)); @@ -4701,18 +4637,462 @@ bpf_object__probe_loading(struct bpf_object *obj) return 0; } +static int probe_fd(int fd) +{ + if (fd >= 0) + close(fd); + return fd >= 0; +} + +static int probe_kern_prog_name(void) +{ + const size_t attr_sz = offsetofend(union bpf_attr, prog_name); + struct bpf_insn insns[] = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + union bpf_attr attr; + int ret; + + memset(&attr, 0, attr_sz); + attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER; + attr.license = ptr_to_u64("GPL"); + attr.insns = ptr_to_u64(insns); + attr.insn_cnt = (__u32)ARRAY_SIZE(insns); + libbpf_strlcpy(attr.prog_name, "libbpf_nametest", sizeof(attr.prog_name)); + + /* make sure loading with name works */ + ret = sys_bpf_prog_load(&attr, attr_sz, PROG_LOAD_ATTEMPTS); + return probe_fd(ret); +} + +static int probe_kern_global_data(void) +{ + char *cp, errmsg[STRERR_BUFSIZE]; + struct bpf_insn insns[] = { + BPF_LD_MAP_VALUE(BPF_REG_1, 0, 16), + BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 42), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + int ret, map, insn_cnt = ARRAY_SIZE(insns); + + map = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_global", sizeof(int), 32, 1, NULL); + if (map < 0) { + ret = -errno; + cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg)); + pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n", + __func__, cp, -ret); + return ret; + } + + insns[0].imm = map; + + ret = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, NULL); + close(map); + return probe_fd(ret); +} + +static int probe_kern_btf(void) +{ + static const char strs[] = "\0int"; + __u32 types[] = { + /* int */ + BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), + }; + + return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), + strs, sizeof(strs))); +} + +static int probe_kern_btf_func(void) +{ + static const char strs[] = "\0int\0x\0a"; + /* void x(int a) {} */ + __u32 types[] = { + /* int */ + BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ + /* FUNC_PROTO */ /* [2] */ + BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0), + BTF_PARAM_ENC(7, 1), + /* FUNC x */ /* [3] */ + BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0), 2), + }; + + return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), + strs, sizeof(strs))); +} + +static int probe_kern_btf_func_global(void) +{ + static const char strs[] = "\0int\0x\0a"; + /* static void x(int a) {} */ + __u32 types[] = { + /* int */ + BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ + /* FUNC_PROTO */ /* [2] */ + BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0), + BTF_PARAM_ENC(7, 1), + /* FUNC x BTF_FUNC_GLOBAL */ /* [3] */ + BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, BTF_FUNC_GLOBAL), 2), + }; + + return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), + strs, sizeof(strs))); +} + +static int probe_kern_btf_datasec(void) +{ + static const char strs[] = "\0x\0.data"; + /* static int a; */ + __u32 types[] = { + /* int */ + BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ + /* VAR x */ /* [2] */ + BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1), + BTF_VAR_STATIC, + /* DATASEC val */ /* [3] */ + BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4), + BTF_VAR_SECINFO_ENC(2, 0, 4), + }; + + return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), + strs, sizeof(strs))); +} + +static int probe_kern_btf_float(void) +{ + static const char strs[] = "\0float"; + __u32 types[] = { + /* float */ + BTF_TYPE_FLOAT_ENC(1, 4), + }; + + return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), + strs, sizeof(strs))); +} + +static int probe_kern_btf_decl_tag(void) +{ + static const char strs[] = "\0tag"; + __u32 types[] = { + /* int */ + BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ + /* VAR x */ /* [2] */ + BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1), + BTF_VAR_STATIC, + /* attr */ + BTF_TYPE_DECL_TAG_ENC(1, 2, -1), + }; + + return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), + strs, sizeof(strs))); +} + +static int probe_kern_btf_type_tag(void) +{ + static const char strs[] = "\0tag"; + __u32 types[] = { + /* int */ + BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ + /* attr */ + BTF_TYPE_TYPE_TAG_ENC(1, 1), /* [2] */ + /* ptr */ + BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 2), /* [3] */ + }; + + return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), + strs, sizeof(strs))); +} + +static int probe_kern_array_mmap(void) +{ + LIBBPF_OPTS(bpf_map_create_opts, opts, .map_flags = BPF_F_MMAPABLE); + int fd; + + fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_mmap", sizeof(int), sizeof(int), 1, &opts); + return probe_fd(fd); +} + +static int probe_kern_exp_attach_type(void) +{ + LIBBPF_OPTS(bpf_prog_load_opts, opts, .expected_attach_type = BPF_CGROUP_INET_SOCK_CREATE); + struct bpf_insn insns[] = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + int fd, insn_cnt = ARRAY_SIZE(insns); + + /* use any valid combination of program type and (optional) + * non-zero expected attach type (i.e., not a BPF_CGROUP_INET_INGRESS) + * to see if kernel supports expected_attach_type field for + * BPF_PROG_LOAD command + */ + fd = bpf_prog_load(BPF_PROG_TYPE_CGROUP_SOCK, NULL, "GPL", insns, insn_cnt, &opts); + return probe_fd(fd); +} + +static int probe_kern_probe_read_kernel(void) +{ + struct bpf_insn insns[] = { + BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), /* r1 = r10 (fp) */ + BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8), /* r1 += -8 */ + BPF_MOV64_IMM(BPF_REG_2, 8), /* r2 = 8 */ + BPF_MOV64_IMM(BPF_REG_3, 0), /* r3 = 0 */ + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_probe_read_kernel), + BPF_EXIT_INSN(), + }; + int fd, insn_cnt = ARRAY_SIZE(insns); + + fd = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", insns, insn_cnt, NULL); + return probe_fd(fd); +} + +static int probe_prog_bind_map(void) +{ + char *cp, errmsg[STRERR_BUFSIZE]; + struct bpf_insn insns[] = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + int ret, map, prog, insn_cnt = ARRAY_SIZE(insns); + + map = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_det_bind", sizeof(int), 32, 1, NULL); + if (map < 0) { + ret = -errno; + cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg)); + pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n", + __func__, cp, -ret); + return ret; + } + + prog = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, NULL); + if (prog < 0) { + close(map); + return 0; + } + + ret = bpf_prog_bind_map(prog, map, NULL); + + close(map); + close(prog); + + return ret >= 0; +} + +static int probe_module_btf(void) +{ + static const char strs[] = "\0int"; + __u32 types[] = { + /* int */ + BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), + }; + struct bpf_btf_info info; + __u32 len = sizeof(info); + char name[16]; + int fd, err; + + fd = libbpf__load_raw_btf((char *)types, sizeof(types), strs, sizeof(strs)); + if (fd < 0) + return 0; /* BTF not supported at all */ + + memset(&info, 0, sizeof(info)); + info.name = ptr_to_u64(name); + info.name_len = sizeof(name); + + /* check that BPF_OBJ_GET_INFO_BY_FD supports specifying name pointer; + * kernel's module BTF support coincides with support for + * name/name_len fields in struct bpf_btf_info. + */ + err = bpf_btf_get_info_by_fd(fd, &info, &len); + close(fd); + return !err; +} + +static int probe_perf_link(void) +{ + struct bpf_insn insns[] = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + int prog_fd, link_fd, err; + + prog_fd = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", + insns, ARRAY_SIZE(insns), NULL); + if (prog_fd < 0) + return -errno; + + /* use invalid perf_event FD to get EBADF, if link is supported; + * otherwise EINVAL should be returned + */ + link_fd = bpf_link_create(prog_fd, -1, BPF_PERF_EVENT, NULL); + err = -errno; /* close() can clobber errno */ + + if (link_fd >= 0) + close(link_fd); + close(prog_fd); + + return link_fd < 0 && err == -EBADF; +} + +static int probe_uprobe_multi_link(void) +{ + LIBBPF_OPTS(bpf_prog_load_opts, load_opts, + .expected_attach_type = BPF_TRACE_UPROBE_MULTI, + ); + LIBBPF_OPTS(bpf_link_create_opts, link_opts); + struct bpf_insn insns[] = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + int prog_fd, link_fd, err; + unsigned long offset = 0; + + prog_fd = bpf_prog_load(BPF_PROG_TYPE_KPROBE, NULL, "GPL", + insns, ARRAY_SIZE(insns), &load_opts); + if (prog_fd < 0) + return -errno; + + /* Creating uprobe in '/' binary should fail with -EBADF. */ + link_opts.uprobe_multi.path = "/"; + link_opts.uprobe_multi.offsets = &offset; + link_opts.uprobe_multi.cnt = 1; + + link_fd = bpf_link_create(prog_fd, -1, BPF_TRACE_UPROBE_MULTI, &link_opts); + err = -errno; /* close() can clobber errno */ + + if (link_fd >= 0) + close(link_fd); + close(prog_fd); + + return link_fd < 0 && err == -EBADF; +} + +static int probe_kern_bpf_cookie(void) +{ + struct bpf_insn insns[] = { + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_get_attach_cookie), + BPF_EXIT_INSN(), + }; + int ret, insn_cnt = ARRAY_SIZE(insns); + + ret = bpf_prog_load(BPF_PROG_TYPE_KPROBE, NULL, "GPL", insns, insn_cnt, NULL); + return probe_fd(ret); +} + +static int probe_kern_btf_enum64(void) +{ + static const char strs[] = "\0enum64"; + __u32 types[] = { + BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_ENUM64, 0, 0), 8), + }; + + return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), + strs, sizeof(strs))); +} + +static int probe_kern_syscall_wrapper(void); + +enum kern_feature_result { + FEAT_UNKNOWN = 0, + FEAT_SUPPORTED = 1, + FEAT_MISSING = 2, +}; + +typedef int (*feature_probe_fn)(void); + +static struct kern_feature_desc { + const char *desc; + feature_probe_fn probe; + enum kern_feature_result res; +} feature_probes[__FEAT_CNT] = { + [FEAT_PROG_NAME] = { + "BPF program name", probe_kern_prog_name, + }, + [FEAT_GLOBAL_DATA] = { + "global variables", probe_kern_global_data, + }, + [FEAT_BTF] = { + "minimal BTF", probe_kern_btf, + }, + [FEAT_BTF_FUNC] = { + "BTF functions", probe_kern_btf_func, + }, + [FEAT_BTF_GLOBAL_FUNC] = { + "BTF global function", probe_kern_btf_func_global, + }, + [FEAT_BTF_DATASEC] = { + "BTF data section and variable", probe_kern_btf_datasec, + }, + [FEAT_ARRAY_MMAP] = { + "ARRAY map mmap()", probe_kern_array_mmap, + }, + [FEAT_EXP_ATTACH_TYPE] = { + "BPF_PROG_LOAD expected_attach_type attribute", + probe_kern_exp_attach_type, + }, + [FEAT_PROBE_READ_KERN] = { + "bpf_probe_read_kernel() helper", probe_kern_probe_read_kernel, + }, + [FEAT_PROG_BIND_MAP] = { + "BPF_PROG_BIND_MAP support", probe_prog_bind_map, + }, + [FEAT_MODULE_BTF] = { + "module BTF support", probe_module_btf, + }, + [FEAT_BTF_FLOAT] = { + "BTF_KIND_FLOAT support", probe_kern_btf_float, + }, + [FEAT_PERF_LINK] = { + "BPF perf link support", probe_perf_link, + }, + [FEAT_BTF_DECL_TAG] = { + "BTF_KIND_DECL_TAG support", probe_kern_btf_decl_tag, + }, + [FEAT_BTF_TYPE_TAG] = { + "BTF_KIND_TYPE_TAG support", probe_kern_btf_type_tag, + }, + [FEAT_MEMCG_ACCOUNT] = { + "memcg-based memory accounting", probe_memcg_account, + }, + [FEAT_BPF_COOKIE] = { + "BPF cookie support", probe_kern_bpf_cookie, + }, + [FEAT_BTF_ENUM64] = { + "BTF_KIND_ENUM64 support", probe_kern_btf_enum64, + }, + [FEAT_SYSCALL_WRAPPER] = { + "Kernel using syscall wrapper", probe_kern_syscall_wrapper, + }, + [FEAT_UPROBE_MULTI_LINK] = { + "BPF multi-uprobe link support", probe_uprobe_multi_link, + }, +}; + bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id) { + struct kern_feature_desc *feat = &feature_probes[feat_id]; + int ret; + if (obj && obj->gen_loader) /* To generate loader program assume the latest kernel * to avoid doing extra prog_load, map_create syscalls. */ return true; - if (obj->token_fd) - return feat_supported(obj->feat_cache, feat_id); + if (READ_ONCE(feat->res) == FEAT_UNKNOWN) { + ret = feat->probe(); + if (ret > 0) { + WRITE_ONCE(feat->res, FEAT_SUPPORTED); + } else if (ret == 0) { + WRITE_ONCE(feat->res, FEAT_MISSING); + } else { + pr_warn("Detection of kernel %s support failed: %d\n", feat->desc, ret); + WRITE_ONCE(feat->res, FEAT_MISSING); + } + } - return feat_supported(NULL, feat_id); + return READ_ONCE(feat->res) == FEAT_SUPPORTED; } static bool map_is_reuse_compat(const struct bpf_map *map, int map_fd) @@ -4831,7 +5211,6 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, b create_attr.map_flags = def->map_flags; create_attr.numa_node = map->numa_node; create_attr.map_extra = map->map_extra; - create_attr.token_fd = obj->token_fd; if (bpf_map__is_struct_ops(map)) create_attr.btf_vmlinux_value_type_id = map->btf_vmlinux_value_type_id; @@ -6667,7 +7046,6 @@ static int bpf_object_load_prog(struct bpf_object *obj, struct bpf_program *prog load_attr.attach_btf_id = prog->attach_btf_id; load_attr.kern_version = kern_version; load_attr.prog_ifindex = prog->prog_ifindex; - load_attr.token_fd = obj->token_fd; /* specify func_info/line_info only if kernel supports them */ btf_fd = bpf_object__btf_fd(obj); @@ -7129,10 +7507,10 @@ static int bpf_object_init_progs(struct bpf_object *obj, const struct bpf_object static struct bpf_object *bpf_object_open(const char *path, const void *obj_buf, size_t obj_buf_sz, const struct bpf_object_open_opts *opts) { - const char *obj_name, *kconfig, *btf_tmp_path, *token_path; + const char *obj_name, *kconfig, *btf_tmp_path; struct bpf_object *obj; char tmp_name[64]; - int err, token_fd; + int err; char *log_buf; size_t log_size; __u32 log_level; @@ -7166,28 +7544,6 @@ static struct bpf_object *bpf_object_open(const char *path, const void *obj_buf, if (log_size && !log_buf) return ERR_PTR(-EINVAL); - token_path = OPTS_GET(opts, bpf_token_path, NULL); - token_fd = OPTS_GET(opts, bpf_token_fd, -1); - /* non-empty token path can't be combined with invalid token FD */ - if (token_path && token_path[0] != '\0' && token_fd < 0) - return ERR_PTR(-EINVAL); - /* empty token path can't be combined with valid token FD */ - if (token_path && token_path[0] == '\0' && token_fd > 0) - return ERR_PTR(-EINVAL); - /* if user didn't specify bpf_token_path/bpf_token_fd explicitly, - * check if LIBBPF_BPF_TOKEN_PATH envvar was set and treat it as - * bpf_token_path option - */ - if (token_fd == 0 && !token_path) - token_path = getenv("LIBBPF_BPF_TOKEN_PATH"); - /* empty token_path is equivalent to invalid token_fd */ - if (token_path && token_path[0] == '\0') { - token_path = NULL; - token_fd = -1; - } - if (token_path && strlen(token_path) >= PATH_MAX) - return ERR_PTR(-ENAMETOOLONG); - obj = bpf_object__new(path, obj_buf, obj_buf_sz, obj_name); if (IS_ERR(obj)) return obj; @@ -7196,19 +7552,6 @@ static struct bpf_object *bpf_object_open(const char *path, const void *obj_buf, obj->log_size = log_size; obj->log_level = log_level; - obj->token_fd = token_fd <= 0 ? token_fd : dup_good_fd(token_fd); - if (token_fd > 0 && obj->token_fd < 0) { - err = -errno; - goto out; - } - if (token_path) { - obj->token_path = strdup(token_path); - if (!obj->token_path) { - err = -ENOMEM; - goto out; - } - } - btf_tmp_path = OPTS_GET(opts, btf_custom_path, NULL); if (btf_tmp_path) { if (strlen(btf_tmp_path) >= PATH_MAX) { @@ -7719,8 +8062,7 @@ static int bpf_object_load(struct bpf_object *obj, int extra_log_level, const ch if (obj->gen_loader) bpf_gen__init(obj->gen_loader, extra_log_level, obj->nr_programs, obj->nr_maps); - err = bpf_object_prepare_token(obj); - err = err ? : bpf_object__probe_loading(obj); + err = bpf_object__probe_loading(obj); err = err ? : bpf_object__load_vmlinux_btf(obj, false); err = err ? : bpf_object__resolve_externs(obj, obj->kconfig); err = err ? : bpf_object__sanitize_and_load_btf(obj); @@ -8257,11 +8599,6 @@ void bpf_object__close(struct bpf_object *obj) } zfree(&obj->programs); - zfree(&obj->feat_cache); - zfree(&obj->token_path); - if (obj->token_fd > 0) - close(obj->token_fd); - free(obj); } @@ -10275,7 +10612,7 @@ static const char *arch_specific_syscall_pfx(void) #endif } -int probe_kern_syscall_wrapper(int token_fd) +static int probe_kern_syscall_wrapper(void) { char syscall_name[64]; const char *ksys_pfx; diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 916904bd2a7a..6cd9c501624f 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -177,45 +177,10 @@ struct bpf_object_open_opts { * logs through its print callback. */ __u32 kernel_log_level; - /* FD of a BPF token instantiated by user through bpf_token_create() - * API. BPF object will keep dup()'ed FD internally, so passed token - * FD can be closed after BPF object/skeleton open step. - * - * Setting bpf_token_fd to negative value disables libbpf's automatic - * attempt to create BPF token from default BPF FS mount point - * (/sys/fs/bpf), in case this default behavior is undesirable. - * - * If bpf_token_path and bpf_token_fd are not specified, libbpf will - * consult LIBBPF_BPF_TOKEN_PATH environment variable. If set, it will - * be taken as a value of bpf_token_path option and will force libbpf - * to either create BPF token from provided custom BPF FS path, or - * will disable implicit BPF token creation, if envvar value is an - * empty string. - * - * bpf_token_path and bpf_token_fd are mutually exclusive and only one - * of those options should be set. Either of them overrides - * LIBBPF_BPF_TOKEN_PATH envvar. - */ - int bpf_token_fd; - /* Path to BPF FS mount point to derive BPF token from. - * - * Created BPF token will be used for all bpf() syscall operations - * that accept BPF token (e.g., map creation, BTF and program loads, - * etc) automatically within instantiated BPF object. - * - * Setting bpf_token_path option to empty string disables libbpf's - * automatic attempt to create BPF token from default BPF FS mount - * point (/sys/fs/bpf), in case this default behavior is undesirable. - * - * bpf_token_path and bpf_token_fd are mutually exclusive and only one - * of those options should be set. Either of them overrides - * LIBBPF_BPF_TOKEN_PATH envvar. - */ - const char *bpf_token_path; size_t :0; }; -#define bpf_object_open_opts__last_field bpf_token_path +#define bpf_object_open_opts__last_field kernel_log_level /** * @brief **bpf_object__open()** creates a bpf_object by opening diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index df7657b65c47..91c5aef7dae7 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -401,7 +401,6 @@ LIBBPF_1.3.0 { bpf_program__attach_netkit; bpf_program__attach_tcx; bpf_program__attach_uprobe_multi; - bpf_token_create; ring__avail_data_size; ring__consume; ring__consumer_pos; diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index 4cda32298c49..b5d334754e5d 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -360,32 +360,15 @@ enum kern_feature_id { __FEAT_CNT, }; -enum kern_feature_result { - FEAT_UNKNOWN = 0, - FEAT_SUPPORTED = 1, - FEAT_MISSING = 2, -}; - -struct kern_feature_cache { - enum kern_feature_result res[__FEAT_CNT]; - int token_fd; -}; - -bool feat_supported(struct kern_feature_cache *cache, enum kern_feature_id feat_id); +int probe_memcg_account(void); bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id); - -int probe_kern_syscall_wrapper(int token_fd); -int probe_memcg_account(int token_fd); int bump_rlimit_memlock(void); int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz); int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz); int libbpf__load_raw_btf(const char *raw_types, size_t types_len, - const char *str_sec, size_t str_len, - int token_fd); -int btf_load_into_kernel(struct btf *btf, - char *log_buf, size_t log_sz, __u32 log_level, - int token_fd); + const char *str_sec, size_t str_len); +int btf_load_into_kernel(struct btf *btf, char *log_buf, size_t log_sz, __u32 log_level); struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf); void btf_get_kernel_prefix_kind(enum bpf_attach_type attach_type, @@ -549,17 +532,6 @@ static inline bool is_ldimm64_insn(struct bpf_insn *insn) return insn->code == (BPF_LD | BPF_IMM | BPF_DW); } -/* Unconditionally dup FD, ensuring it doesn't use [0, 2] range. - * Original FD is not closed or altered in any other way. - * Preserves original FD value, if it's invalid (negative). - */ -static inline int dup_good_fd(int fd) -{ - if (fd < 0) - return fd; - return fcntl(fd, F_DUPFD_CLOEXEC, 3); -} - /* if fd is stdin, stdout, or stderr, dup to a fd greater than 2 * Takes ownership of the fd passed in, and closes it if calling * fcntl(fd, F_DUPFD_CLOEXEC, 3). @@ -571,7 +543,7 @@ static inline int ensure_good_fd(int fd) if (fd < 0) return fd; if (fd < 3) { - fd = dup_good_fd(fd); + fd = fcntl(fd, F_DUPFD_CLOEXEC, 3); saved_errno = errno; close(old_fd); errno = saved_errno; diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c index 8e7437006639..9c4db90b92b6 100644 --- a/tools/lib/bpf/libbpf_probes.c +++ b/tools/lib/bpf/libbpf_probes.c @@ -219,8 +219,7 @@ int libbpf_probe_bpf_prog_type(enum bpf_prog_type prog_type, const void *opts) } int libbpf__load_raw_btf(const char *raw_types, size_t types_len, - const char *str_sec, size_t str_len, - int token_fd) + const char *str_sec, size_t str_len) { struct btf_header hdr = { .magic = BTF_MAGIC, @@ -230,7 +229,6 @@ int libbpf__load_raw_btf(const char *raw_types, size_t types_len, .str_off = types_len, .str_len = str_len, }; - LIBBPF_OPTS(bpf_btf_load_opts, opts, .token_fd = token_fd); int btf_fd, btf_len; __u8 *raw_btf; @@ -243,7 +241,7 @@ int libbpf__load_raw_btf(const char *raw_types, size_t types_len, memcpy(raw_btf + hdr.hdr_len, raw_types, hdr.type_len); memcpy(raw_btf + hdr.hdr_len + hdr.type_len, str_sec, hdr.str_len); - btf_fd = bpf_btf_load(raw_btf, btf_len, &opts); + btf_fd = bpf_btf_load(raw_btf, btf_len, NULL); free(raw_btf); return btf_fd; @@ -273,7 +271,7 @@ static int load_local_storage_btf(void) }; return libbpf__load_raw_btf((char *)types, sizeof(types), - strs, sizeof(strs), 0); + strs, sizeof(strs)); } static int probe_map_create(enum bpf_map_type map_type) diff --git a/tools/lib/bpf/str_error.h b/tools/lib/bpf/str_error.h index 626d7ffb03d6..a139334d57b6 100644 --- a/tools/lib/bpf/str_error.h +++ b/tools/lib/bpf/str_error.h @@ -2,8 +2,5 @@ #ifndef __LIBBPF_STR_ERROR_H #define __LIBBPF_STR_ERROR_H -#define STRERR_BUFSIZE 128 - char *libbpf_strerror_r(int err, char *dst, int len); - #endif /* __LIBBPF_STR_ERROR_H */ diff --git a/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c b/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c index 4ed46ed58a7b..9f766ddd946a 100644 --- a/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c +++ b/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c @@ -30,8 +30,6 @@ void test_libbpf_probe_prog_types(void) if (prog_type == BPF_PROG_TYPE_UNSPEC) continue; - if (strcmp(prog_type_name, "__MAX_BPF_PROG_TYPE") == 0) - continue; if (!test__start_subtest(prog_type_name)) continue; @@ -70,8 +68,6 @@ void test_libbpf_probe_map_types(void) if (map_type == BPF_MAP_TYPE_UNSPEC) continue; - if (strcmp(map_type_name, "__MAX_BPF_MAP_TYPE") == 0) - continue; if (!test__start_subtest(map_type_name)) continue; diff --git a/tools/testing/selftests/bpf/prog_tests/libbpf_str.c b/tools/testing/selftests/bpf/prog_tests/libbpf_str.c index 62ea855ec4d0..eb34d612d6f8 100644 --- a/tools/testing/selftests/bpf/prog_tests/libbpf_str.c +++ b/tools/testing/selftests/bpf/prog_tests/libbpf_str.c @@ -132,9 +132,6 @@ static void test_libbpf_bpf_map_type_str(void) const char *map_type_str; char buf[256]; - if (map_type == __MAX_BPF_MAP_TYPE) - continue; - map_type_name = btf__str_by_offset(btf, e->name_off); map_type_str = libbpf_bpf_map_type_str(map_type); ASSERT_OK_PTR(map_type_str, map_type_name); @@ -189,9 +186,6 @@ static void test_libbpf_bpf_prog_type_str(void) const char *prog_type_str; char buf[256]; - if (prog_type == __MAX_BPF_PROG_TYPE) - continue; - prog_type_name = btf__str_by_offset(btf, e->name_off); prog_type_str = libbpf_bpf_prog_type_str(prog_type); ASSERT_OK_PTR(prog_type_str, prog_type_name); diff --git a/tools/testing/selftests/bpf/prog_tests/token.c b/tools/testing/selftests/bpf/prog_tests/token.c deleted file mode 100644 index b5dce630e0e1..000000000000 --- a/tools/testing/selftests/bpf/prog_tests/token.c +++ /dev/null @@ -1,1031 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */ -#define _GNU_SOURCE -#include -#include -#include "cap_helpers.h" -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include "priv_map.skel.h" -#include "priv_prog.skel.h" -#include "dummy_st_ops_success.skel.h" - -static inline int sys_mount(const char *dev_name, const char *dir_name, - const char *type, unsigned long flags, - const void *data) -{ - return syscall(__NR_mount, dev_name, dir_name, type, flags, data); -} - -static inline int sys_fsopen(const char *fsname, unsigned flags) -{ - return syscall(__NR_fsopen, fsname, flags); -} - -static inline int sys_fspick(int dfd, const char *path, unsigned flags) -{ - return syscall(__NR_fspick, dfd, path, flags); -} - -static inline int sys_fsconfig(int fs_fd, unsigned cmd, const char *key, const void *val, int aux) -{ - return syscall(__NR_fsconfig, fs_fd, cmd, key, val, aux); -} - -static inline int sys_fsmount(int fs_fd, unsigned flags, unsigned ms_flags) -{ - return syscall(__NR_fsmount, fs_fd, flags, ms_flags); -} - -static inline int sys_move_mount(int from_dfd, const char *from_path, - int to_dfd, const char *to_path, - unsigned flags) -{ - return syscall(__NR_move_mount, from_dfd, from_path, to_dfd, to_path, flags); -} - -static int drop_priv_caps(__u64 *old_caps) -{ - return cap_disable_effective((1ULL << CAP_BPF) | - (1ULL << CAP_PERFMON) | - (1ULL << CAP_NET_ADMIN) | - (1ULL << CAP_SYS_ADMIN), old_caps); -} - -static int restore_priv_caps(__u64 old_caps) -{ - return cap_enable_effective(old_caps, NULL); -} - -static int set_delegate_mask(int fs_fd, const char *key, __u64 mask, const char *mask_str) -{ - char buf[32]; - int err; - - if (!mask_str) { - if (mask == ~0ULL) { - mask_str = "any"; - } else { - snprintf(buf, sizeof(buf), "0x%llx", (unsigned long long)mask); - mask_str = buf; - } - } - - err = sys_fsconfig(fs_fd, FSCONFIG_SET_STRING, key, - mask_str, 0); - if (err < 0) - err = -errno; - return err; -} - -#define zclose(fd) do { if (fd >= 0) close(fd); fd = -1; } while (0) - -struct bpffs_opts { - __u64 cmds; - __u64 maps; - __u64 progs; - __u64 attachs; - const char *cmds_str; - const char *maps_str; - const char *progs_str; - const char *attachs_str; -}; - -static int create_bpffs_fd(void) -{ - int fs_fd; - - /* create VFS context */ - fs_fd = sys_fsopen("bpf", 0); - ASSERT_GE(fs_fd, 0, "fs_fd"); - - return fs_fd; -} - -static int materialize_bpffs_fd(int fs_fd, struct bpffs_opts *opts) -{ - int mnt_fd, err; - - /* set up token delegation mount options */ - err = set_delegate_mask(fs_fd, "delegate_cmds", opts->cmds, opts->cmds_str); - if (!ASSERT_OK(err, "fs_cfg_cmds")) - return err; - err = set_delegate_mask(fs_fd, "delegate_maps", opts->maps, opts->maps_str); - if (!ASSERT_OK(err, "fs_cfg_maps")) - return err; - err = set_delegate_mask(fs_fd, "delegate_progs", opts->progs, opts->progs_str); - if (!ASSERT_OK(err, "fs_cfg_progs")) - return err; - err = set_delegate_mask(fs_fd, "delegate_attachs", opts->attachs, opts->attachs_str); - if (!ASSERT_OK(err, "fs_cfg_attachs")) - return err; - - /* instantiate FS object */ - err = sys_fsconfig(fs_fd, FSCONFIG_CMD_CREATE, NULL, NULL, 0); - if (err < 0) - return -errno; - - /* create O_PATH fd for detached mount */ - mnt_fd = sys_fsmount(fs_fd, 0, 0); - if (err < 0) - return -errno; - - return mnt_fd; -} - -/* send FD over Unix domain (AF_UNIX) socket */ -static int sendfd(int sockfd, int fd) -{ - struct msghdr msg = {}; - struct cmsghdr *cmsg; - int fds[1] = { fd }, err; - char iobuf[1]; - struct iovec io = { - .iov_base = iobuf, - .iov_len = sizeof(iobuf), - }; - union { - char buf[CMSG_SPACE(sizeof(fds))]; - struct cmsghdr align; - } u; - - msg.msg_iov = &io; - msg.msg_iovlen = 1; - msg.msg_control = u.buf; - msg.msg_controllen = sizeof(u.buf); - cmsg = CMSG_FIRSTHDR(&msg); - cmsg->cmsg_level = SOL_SOCKET; - cmsg->cmsg_type = SCM_RIGHTS; - cmsg->cmsg_len = CMSG_LEN(sizeof(fds)); - memcpy(CMSG_DATA(cmsg), fds, sizeof(fds)); - - err = sendmsg(sockfd, &msg, 0); - if (err < 0) - err = -errno; - if (!ASSERT_EQ(err, 1, "sendmsg")) - return -EINVAL; - - return 0; -} - -/* receive FD over Unix domain (AF_UNIX) socket */ -static int recvfd(int sockfd, int *fd) -{ - struct msghdr msg = {}; - struct cmsghdr *cmsg; - int fds[1], err; - char iobuf[1]; - struct iovec io = { - .iov_base = iobuf, - .iov_len = sizeof(iobuf), - }; - union { - char buf[CMSG_SPACE(sizeof(fds))]; - struct cmsghdr align; - } u; - - msg.msg_iov = &io; - msg.msg_iovlen = 1; - msg.msg_control = u.buf; - msg.msg_controllen = sizeof(u.buf); - - err = recvmsg(sockfd, &msg, 0); - if (err < 0) - err = -errno; - if (!ASSERT_EQ(err, 1, "recvmsg")) - return -EINVAL; - - cmsg = CMSG_FIRSTHDR(&msg); - if (!ASSERT_OK_PTR(cmsg, "cmsg_null") || - !ASSERT_EQ(cmsg->cmsg_len, CMSG_LEN(sizeof(fds)), "cmsg_len") || - !ASSERT_EQ(cmsg->cmsg_level, SOL_SOCKET, "cmsg_level") || - !ASSERT_EQ(cmsg->cmsg_type, SCM_RIGHTS, "cmsg_type")) - return -EINVAL; - - memcpy(fds, CMSG_DATA(cmsg), sizeof(fds)); - *fd = fds[0]; - - return 0; -} - -static ssize_t write_nointr(int fd, const void *buf, size_t count) -{ - ssize_t ret; - - do { - ret = write(fd, buf, count); - } while (ret < 0 && errno == EINTR); - - return ret; -} - -static int write_file(const char *path, const void *buf, size_t count) -{ - int fd; - ssize_t ret; - - fd = open(path, O_WRONLY | O_CLOEXEC | O_NOCTTY | O_NOFOLLOW); - if (fd < 0) - return -1; - - ret = write_nointr(fd, buf, count); - close(fd); - if (ret < 0 || (size_t)ret != count) - return -1; - - return 0; -} - -static int create_and_enter_userns(void) -{ - uid_t uid; - gid_t gid; - char map[100]; - - uid = getuid(); - gid = getgid(); - - if (unshare(CLONE_NEWUSER)) - return -1; - - if (write_file("/proc/self/setgroups", "deny", sizeof("deny") - 1) && - errno != ENOENT) - return -1; - - snprintf(map, sizeof(map), "0 %d 1", uid); - if (write_file("/proc/self/uid_map", map, strlen(map))) - return -1; - - - snprintf(map, sizeof(map), "0 %d 1", gid); - if (write_file("/proc/self/gid_map", map, strlen(map))) - return -1; - - if (setgid(0)) - return -1; - - if (setuid(0)) - return -1; - - return 0; -} - -typedef int (*child_callback_fn)(int); - -static void child(int sock_fd, struct bpffs_opts *opts, child_callback_fn callback) -{ - LIBBPF_OPTS(bpf_map_create_opts, map_opts); - int mnt_fd = -1, fs_fd = -1, err = 0, bpffs_fd = -1; - - /* setup userns with root mappings */ - err = create_and_enter_userns(); - if (!ASSERT_OK(err, "create_and_enter_userns")) - goto cleanup; - - /* setup mountns to allow creating BPF FS (fsopen("bpf")) from unpriv process */ - err = unshare(CLONE_NEWNS); - if (!ASSERT_OK(err, "create_mountns")) - goto cleanup; - - err = sys_mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0); - if (!ASSERT_OK(err, "remount_root")) - goto cleanup; - - fs_fd = create_bpffs_fd(); - if (!ASSERT_GE(fs_fd, 0, "create_bpffs_fd")) { - err = -EINVAL; - goto cleanup; - } - - /* ensure unprivileged child cannot set delegation options */ - err = set_delegate_mask(fs_fd, "delegate_cmds", 0x1, NULL); - ASSERT_EQ(err, -EPERM, "delegate_cmd_eperm"); - err = set_delegate_mask(fs_fd, "delegate_maps", 0x1, NULL); - ASSERT_EQ(err, -EPERM, "delegate_maps_eperm"); - err = set_delegate_mask(fs_fd, "delegate_progs", 0x1, NULL); - ASSERT_EQ(err, -EPERM, "delegate_progs_eperm"); - err = set_delegate_mask(fs_fd, "delegate_attachs", 0x1, NULL); - ASSERT_EQ(err, -EPERM, "delegate_attachs_eperm"); - - /* pass BPF FS context object to parent */ - err = sendfd(sock_fd, fs_fd); - if (!ASSERT_OK(err, "send_fs_fd")) - goto cleanup; - zclose(fs_fd); - - /* avoid mucking around with mount namespaces and mounting at - * well-known path, just get detach-mounted BPF FS fd back from parent - */ - err = recvfd(sock_fd, &mnt_fd); - if (!ASSERT_OK(err, "recv_mnt_fd")) - goto cleanup; - - /* try to fspick() BPF FS and try to add some delegation options */ - fs_fd = sys_fspick(mnt_fd, "", FSPICK_EMPTY_PATH); - if (!ASSERT_GE(fs_fd, 0, "bpffs_fspick")) { - err = -EINVAL; - goto cleanup; - } - - /* ensure unprivileged child cannot reconfigure to set delegation options */ - err = set_delegate_mask(fs_fd, "delegate_cmds", 0, "any"); - if (!ASSERT_EQ(err, -EPERM, "delegate_cmd_eperm_reconfig")) { - err = -EINVAL; - goto cleanup; - } - err = set_delegate_mask(fs_fd, "delegate_maps", 0, "any"); - if (!ASSERT_EQ(err, -EPERM, "delegate_maps_eperm_reconfig")) { - err = -EINVAL; - goto cleanup; - } - err = set_delegate_mask(fs_fd, "delegate_progs", 0, "any"); - if (!ASSERT_EQ(err, -EPERM, "delegate_progs_eperm_reconfig")) { - err = -EINVAL; - goto cleanup; - } - err = set_delegate_mask(fs_fd, "delegate_attachs", 0, "any"); - if (!ASSERT_EQ(err, -EPERM, "delegate_attachs_eperm_reconfig")) { - err = -EINVAL; - goto cleanup; - } - zclose(fs_fd); - - bpffs_fd = openat(mnt_fd, ".", 0, O_RDWR); - if (!ASSERT_GE(bpffs_fd, 0, "bpffs_open")) { - err = -EINVAL; - goto cleanup; - } - - /* do custom test logic with customly set up BPF FS instance */ - err = callback(bpffs_fd); - if (!ASSERT_OK(err, "test_callback")) - goto cleanup; - - err = 0; -cleanup: - zclose(sock_fd); - zclose(mnt_fd); - zclose(fs_fd); - zclose(bpffs_fd); - - exit(-err); -} - -static int wait_for_pid(pid_t pid) -{ - int status, ret; - -again: - ret = waitpid(pid, &status, 0); - if (ret == -1) { - if (errno == EINTR) - goto again; - - return -1; - } - - if (!WIFEXITED(status)) - return -1; - - return WEXITSTATUS(status); -} - -static void parent(int child_pid, struct bpffs_opts *bpffs_opts, int sock_fd) -{ - int fs_fd = -1, mnt_fd = -1, err; - - err = recvfd(sock_fd, &fs_fd); - if (!ASSERT_OK(err, "recv_bpffs_fd")) - goto cleanup; - - mnt_fd = materialize_bpffs_fd(fs_fd, bpffs_opts); - if (!ASSERT_GE(mnt_fd, 0, "materialize_bpffs_fd")) { - err = -EINVAL; - goto cleanup; - } - zclose(fs_fd); - - /* pass BPF FS context object to parent */ - err = sendfd(sock_fd, mnt_fd); - if (!ASSERT_OK(err, "send_mnt_fd")) - goto cleanup; - zclose(mnt_fd); - - err = wait_for_pid(child_pid); - ASSERT_OK(err, "waitpid_child"); - -cleanup: - zclose(sock_fd); - zclose(fs_fd); - zclose(mnt_fd); - - if (child_pid > 0) - (void)kill(child_pid, SIGKILL); -} - -static void subtest_userns(struct bpffs_opts *bpffs_opts, child_callback_fn cb) -{ - int sock_fds[2] = { -1, -1 }; - int child_pid = 0, err; - - err = socketpair(AF_UNIX, SOCK_STREAM, 0, sock_fds); - if (!ASSERT_OK(err, "socketpair")) - goto cleanup; - - child_pid = fork(); - if (!ASSERT_GE(child_pid, 0, "fork")) - goto cleanup; - - if (child_pid == 0) { - zclose(sock_fds[0]); - return child(sock_fds[1], bpffs_opts, cb); - - } else { - zclose(sock_fds[1]); - return parent(child_pid, bpffs_opts, sock_fds[0]); - } - -cleanup: - zclose(sock_fds[0]); - zclose(sock_fds[1]); - if (child_pid > 0) - (void)kill(child_pid, SIGKILL); -} - -static int userns_map_create(int mnt_fd) -{ - LIBBPF_OPTS(bpf_map_create_opts, map_opts); - int err, token_fd = -1, map_fd = -1; - __u64 old_caps = 0; - - /* create BPF token from BPF FS mount */ - token_fd = bpf_token_create(mnt_fd, NULL); - if (!ASSERT_GT(token_fd, 0, "token_create")) { - err = -EINVAL; - goto cleanup; - } - - /* while inside non-init userns, we need both a BPF token *and* - * CAP_BPF inside current userns to create privileged map; let's test - * that neither BPF token alone nor namespaced CAP_BPF is sufficient - */ - err = drop_priv_caps(&old_caps); - if (!ASSERT_OK(err, "drop_caps")) - goto cleanup; - - /* no token, no CAP_BPF -> fail */ - map_opts.token_fd = 0; - map_fd = bpf_map_create(BPF_MAP_TYPE_STACK, "wo_token_wo_bpf", 0, 8, 1, &map_opts); - if (!ASSERT_LT(map_fd, 0, "stack_map_wo_token_wo_cap_bpf_should_fail")) { - err = -EINVAL; - goto cleanup; - } - - /* token without CAP_BPF -> fail */ - map_opts.token_fd = token_fd; - map_fd = bpf_map_create(BPF_MAP_TYPE_STACK, "w_token_wo_bpf", 0, 8, 1, &map_opts); - if (!ASSERT_LT(map_fd, 0, "stack_map_w_token_wo_cap_bpf_should_fail")) { - err = -EINVAL; - goto cleanup; - } - - /* get back effective local CAP_BPF (and CAP_SYS_ADMIN) */ - err = restore_priv_caps(old_caps); - if (!ASSERT_OK(err, "restore_caps")) - goto cleanup; - - /* CAP_BPF without token -> fail */ - map_opts.token_fd = 0; - map_fd = bpf_map_create(BPF_MAP_TYPE_STACK, "wo_token_w_bpf", 0, 8, 1, &map_opts); - if (!ASSERT_LT(map_fd, 0, "stack_map_wo_token_w_cap_bpf_should_fail")) { - err = -EINVAL; - goto cleanup; - } - - /* finally, namespaced CAP_BPF + token -> success */ - map_opts.token_fd = token_fd; - map_fd = bpf_map_create(BPF_MAP_TYPE_STACK, "w_token_w_bpf", 0, 8, 1, &map_opts); - if (!ASSERT_GT(map_fd, 0, "stack_map_w_token_w_cap_bpf")) { - err = -EINVAL; - goto cleanup; - } - -cleanup: - zclose(token_fd); - zclose(map_fd); - return err; -} - -static int userns_btf_load(int mnt_fd) -{ - LIBBPF_OPTS(bpf_btf_load_opts, btf_opts); - int err, token_fd = -1, btf_fd = -1; - const void *raw_btf_data; - struct btf *btf = NULL; - __u32 raw_btf_size; - __u64 old_caps = 0; - - /* create BPF token from BPF FS mount */ - token_fd = bpf_token_create(mnt_fd, NULL); - if (!ASSERT_GT(token_fd, 0, "token_create")) { - err = -EINVAL; - goto cleanup; - } - - /* while inside non-init userns, we need both a BPF token *and* - * CAP_BPF inside current userns to create privileged map; let's test - * that neither BPF token alone nor namespaced CAP_BPF is sufficient - */ - err = drop_priv_caps(&old_caps); - if (!ASSERT_OK(err, "drop_caps")) - goto cleanup; - - /* setup a trivial BTF data to load to the kernel */ - btf = btf__new_empty(); - if (!ASSERT_OK_PTR(btf, "empty_btf")) - goto cleanup; - - ASSERT_GT(btf__add_int(btf, "int", 4, 0), 0, "int_type"); - - raw_btf_data = btf__raw_data(btf, &raw_btf_size); - if (!ASSERT_OK_PTR(raw_btf_data, "raw_btf_data")) - goto cleanup; - - /* no token + no CAP_BPF -> failure */ - btf_opts.token_fd = 0; - btf_fd = bpf_btf_load(raw_btf_data, raw_btf_size, &btf_opts); - if (!ASSERT_LT(btf_fd, 0, "no_token_no_cap_should_fail")) - goto cleanup; - - /* token + no CAP_BPF -> failure */ - btf_opts.token_fd = token_fd; - btf_fd = bpf_btf_load(raw_btf_data, raw_btf_size, &btf_opts); - if (!ASSERT_LT(btf_fd, 0, "token_no_cap_should_fail")) - goto cleanup; - - /* get back effective local CAP_BPF (and CAP_SYS_ADMIN) */ - err = restore_priv_caps(old_caps); - if (!ASSERT_OK(err, "restore_caps")) - goto cleanup; - - /* token + CAP_BPF -> success */ - btf_opts.token_fd = token_fd; - btf_fd = bpf_btf_load(raw_btf_data, raw_btf_size, &btf_opts); - if (!ASSERT_GT(btf_fd, 0, "token_and_cap_success")) - goto cleanup; - - err = 0; -cleanup: - btf__free(btf); - zclose(btf_fd); - zclose(token_fd); - return err; -} - -static int userns_prog_load(int mnt_fd) -{ - LIBBPF_OPTS(bpf_prog_load_opts, prog_opts); - int err, token_fd = -1, prog_fd = -1; - struct bpf_insn insns[] = { - /* bpf_jiffies64() requires CAP_BPF */ - BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_jiffies64), - /* bpf_get_current_task() requires CAP_PERFMON */ - BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_get_current_task), - /* r0 = 0; exit; */ - BPF_MOV64_IMM(BPF_REG_0, 0), - BPF_EXIT_INSN(), - }; - size_t insn_cnt = ARRAY_SIZE(insns); - __u64 old_caps = 0; - - /* create BPF token from BPF FS mount */ - token_fd = bpf_token_create(mnt_fd, NULL); - if (!ASSERT_GT(token_fd, 0, "token_create")) { - err = -EINVAL; - goto cleanup; - } - - /* validate we can successfully load BPF program with token; this - * being XDP program (CAP_NET_ADMIN) using bpf_jiffies64() (CAP_BPF) - * and bpf_get_current_task() (CAP_PERFMON) helpers validates we have - * BPF token wired properly in a bunch of places in the kernel - */ - prog_opts.token_fd = token_fd; - prog_opts.expected_attach_type = BPF_XDP; - prog_fd = bpf_prog_load(BPF_PROG_TYPE_XDP, "token_prog", "GPL", - insns, insn_cnt, &prog_opts); - if (!ASSERT_GT(prog_fd, 0, "prog_fd")) { - err = -EPERM; - goto cleanup; - } - - /* no token + caps -> failure */ - prog_opts.token_fd = 0; - prog_fd = bpf_prog_load(BPF_PROG_TYPE_XDP, "token_prog", "GPL", - insns, insn_cnt, &prog_opts); - if (!ASSERT_EQ(prog_fd, -EPERM, "prog_fd_eperm")) { - err = -EPERM; - goto cleanup; - } - - err = drop_priv_caps(&old_caps); - if (!ASSERT_OK(err, "drop_caps")) - goto cleanup; - - /* no caps + token -> failure */ - prog_opts.token_fd = token_fd; - prog_fd = bpf_prog_load(BPF_PROG_TYPE_XDP, "token_prog", "GPL", - insns, insn_cnt, &prog_opts); - if (!ASSERT_EQ(prog_fd, -EPERM, "prog_fd_eperm")) { - err = -EPERM; - goto cleanup; - } - - /* no caps + no token -> definitely a failure */ - prog_opts.token_fd = 0; - prog_fd = bpf_prog_load(BPF_PROG_TYPE_XDP, "token_prog", "GPL", - insns, insn_cnt, &prog_opts); - if (!ASSERT_EQ(prog_fd, -EPERM, "prog_fd_eperm")) { - err = -EPERM; - goto cleanup; - } - - err = 0; -cleanup: - zclose(prog_fd); - zclose(token_fd); - return err; -} - -static int userns_obj_priv_map(int mnt_fd) -{ - LIBBPF_OPTS(bpf_object_open_opts, opts); - char buf[256]; - struct priv_map *skel; - int err, token_fd; - - skel = priv_map__open_and_load(); - if (!ASSERT_ERR_PTR(skel, "obj_tokenless_load")) { - priv_map__destroy(skel); - return -EINVAL; - } - - /* use bpf_token_path to provide BPF FS path */ - snprintf(buf, sizeof(buf), "/proc/self/fd/%d", mnt_fd); - opts.bpf_token_path = buf; - skel = priv_map__open_opts(&opts); - if (!ASSERT_OK_PTR(skel, "obj_token_path_open")) - return -EINVAL; - - err = priv_map__load(skel); - priv_map__destroy(skel); - if (!ASSERT_OK(err, "obj_token_path_load")) - return -EINVAL; - - /* create token and pass it through bpf_token_fd */ - token_fd = bpf_token_create(mnt_fd, NULL); - if (!ASSERT_GT(token_fd, 0, "create_token")) - return -EINVAL; - - opts.bpf_token_path = NULL; - opts.bpf_token_fd = token_fd; - skel = priv_map__open_opts(&opts); - if (!ASSERT_OK_PTR(skel, "obj_token_fd_open")) - return -EINVAL; - - /* we can close our token FD, bpf_object owns dup()'ed FD now */ - close(token_fd); - - err = priv_map__load(skel); - priv_map__destroy(skel); - if (!ASSERT_OK(err, "obj_token_fd_load")) - return -EINVAL; - - return 0; -} - -static int userns_obj_priv_prog(int mnt_fd) -{ - LIBBPF_OPTS(bpf_object_open_opts, opts); - char buf[256]; - struct priv_prog *skel; - int err; - - skel = priv_prog__open_and_load(); - if (!ASSERT_ERR_PTR(skel, "obj_tokenless_load")) { - priv_prog__destroy(skel); - return -EINVAL; - } - - /* use bpf_token_path to provide BPF FS path */ - snprintf(buf, sizeof(buf), "/proc/self/fd/%d", mnt_fd); - opts.bpf_token_path = buf; - skel = priv_prog__open_opts(&opts); - if (!ASSERT_OK_PTR(skel, "obj_token_path_open")) - return -EINVAL; - - err = priv_prog__load(skel); - priv_prog__destroy(skel); - if (!ASSERT_OK(err, "obj_token_path_load")) - return -EINVAL; - - return 0; -} - -/* this test is called with BPF FS that doesn't delegate BPF_BTF_LOAD command, - * which should cause struct_ops application to fail, as BTF won't be uploaded - * into the kernel, even if STRUCT_OPS programs themselves are allowed - */ -static int validate_struct_ops_load(int mnt_fd, bool expect_success) -{ - LIBBPF_OPTS(bpf_object_open_opts, opts); - char buf[256]; - struct dummy_st_ops_success *skel; - int err; - - snprintf(buf, sizeof(buf), "/proc/self/fd/%d", mnt_fd); - opts.bpf_token_path = buf; - skel = dummy_st_ops_success__open_opts(&opts); - if (!ASSERT_OK_PTR(skel, "obj_token_path_open")) - return -EINVAL; - - err = dummy_st_ops_success__load(skel); - dummy_st_ops_success__destroy(skel); - if (expect_success) { - if (!ASSERT_OK(err, "obj_token_path_load")) - return -EINVAL; - } else /* expect failure */ { - if (!ASSERT_ERR(err, "obj_token_path_load")) - return -EINVAL; - } - - return 0; -} - -static int userns_obj_priv_btf_fail(int mnt_fd) -{ - return validate_struct_ops_load(mnt_fd, false /* should fail */); -} - -static int userns_obj_priv_btf_success(int mnt_fd) -{ - return validate_struct_ops_load(mnt_fd, true /* should succeed */); -} - -#define TOKEN_ENVVAR "LIBBPF_BPF_TOKEN_PATH" -#define TOKEN_BPFFS_CUSTOM "/bpf-token-fs" - -static int userns_obj_priv_implicit_token(int mnt_fd) -{ - LIBBPF_OPTS(bpf_object_open_opts, opts); - struct dummy_st_ops_success *skel; - int err; - - /* before we mount BPF FS with token delegation, struct_ops skeleton - * should fail to load - */ - skel = dummy_st_ops_success__open_and_load(); - if (!ASSERT_ERR_PTR(skel, "obj_tokenless_load")) { - dummy_st_ops_success__destroy(skel); - return -EINVAL; - } - - /* mount custom BPF FS over /sys/fs/bpf so that libbpf can create BPF - * token automatically and implicitly - */ - err = sys_move_mount(mnt_fd, "", AT_FDCWD, "/sys/fs/bpf", MOVE_MOUNT_F_EMPTY_PATH); - if (!ASSERT_OK(err, "move_mount_bpffs")) - return -EINVAL; - - /* disable implicit BPF token creation by setting - * LIBBPF_BPF_TOKEN_PATH envvar to empty value, load should fail - */ - err = setenv(TOKEN_ENVVAR, "", 1 /*overwrite*/); - if (!ASSERT_OK(err, "setenv_token_path")) - return -EINVAL; - skel = dummy_st_ops_success__open_and_load(); - if (!ASSERT_ERR_PTR(skel, "obj_token_envvar_disabled_load")) { - unsetenv(TOKEN_ENVVAR); - dummy_st_ops_success__destroy(skel); - return -EINVAL; - } - unsetenv(TOKEN_ENVVAR); - - /* now the same struct_ops skeleton should succeed thanks to libppf - * creating BPF token from /sys/fs/bpf mount point - */ - skel = dummy_st_ops_success__open_and_load(); - if (!ASSERT_OK_PTR(skel, "obj_implicit_token_load")) - return -EINVAL; - - dummy_st_ops_success__destroy(skel); - - /* now disable implicit token through empty bpf_token_path, should fail */ - opts.bpf_token_path = ""; - skel = dummy_st_ops_success__open_opts(&opts); - if (!ASSERT_OK_PTR(skel, "obj_empty_token_path_open")) - return -EINVAL; - - err = dummy_st_ops_success__load(skel); - dummy_st_ops_success__destroy(skel); - if (!ASSERT_ERR(err, "obj_empty_token_path_load")) - return -EINVAL; - - /* now disable implicit token through negative bpf_token_fd, should fail */ - opts.bpf_token_path = NULL; - opts.bpf_token_fd = -1; - skel = dummy_st_ops_success__open_opts(&opts); - if (!ASSERT_OK_PTR(skel, "obj_neg_token_fd_open")) - return -EINVAL; - - err = dummy_st_ops_success__load(skel); - dummy_st_ops_success__destroy(skel); - if (!ASSERT_ERR(err, "obj_neg_token_fd_load")) - return -EINVAL; - - return 0; -} - -static int userns_obj_priv_implicit_token_envvar(int mnt_fd) -{ - LIBBPF_OPTS(bpf_object_open_opts, opts); - struct dummy_st_ops_success *skel; - int err; - - /* before we mount BPF FS with token delegation, struct_ops skeleton - * should fail to load - */ - skel = dummy_st_ops_success__open_and_load(); - if (!ASSERT_ERR_PTR(skel, "obj_tokenless_load")) { - dummy_st_ops_success__destroy(skel); - return -EINVAL; - } - - /* mount custom BPF FS over custom location, so libbpf can't create - * BPF token implicitly, unless pointed to it through - * LIBBPF_BPF_TOKEN_PATH envvar - */ - rmdir(TOKEN_BPFFS_CUSTOM); - if (!ASSERT_OK(mkdir(TOKEN_BPFFS_CUSTOM, 0777), "mkdir_bpffs_custom")) - goto err_out; - err = sys_move_mount(mnt_fd, "", AT_FDCWD, TOKEN_BPFFS_CUSTOM, MOVE_MOUNT_F_EMPTY_PATH); - if (!ASSERT_OK(err, "move_mount_bpffs")) - goto err_out; - - /* even though we have BPF FS with delegation, it's not at default - * /sys/fs/bpf location, so we still fail to load until envvar is set up - */ - skel = dummy_st_ops_success__open_and_load(); - if (!ASSERT_ERR_PTR(skel, "obj_tokenless_load2")) { - dummy_st_ops_success__destroy(skel); - goto err_out; - } - - err = setenv(TOKEN_ENVVAR, TOKEN_BPFFS_CUSTOM, 1 /*overwrite*/); - if (!ASSERT_OK(err, "setenv_token_path")) - goto err_out; - - /* now the same struct_ops skeleton should succeed thanks to libppf - * creating BPF token from custom mount point - */ - skel = dummy_st_ops_success__open_and_load(); - if (!ASSERT_OK_PTR(skel, "obj_implicit_token_load")) - goto err_out; - - dummy_st_ops_success__destroy(skel); - - /* now disable implicit token through empty bpf_token_path, envvar - * will be ignored, should fail - */ - opts.bpf_token_path = ""; - skel = dummy_st_ops_success__open_opts(&opts); - if (!ASSERT_OK_PTR(skel, "obj_empty_token_path_open")) - goto err_out; - - err = dummy_st_ops_success__load(skel); - dummy_st_ops_success__destroy(skel); - if (!ASSERT_ERR(err, "obj_empty_token_path_load")) - goto err_out; - - /* now disable implicit token through negative bpf_token_fd, envvar - * will be ignored, should fail - */ - opts.bpf_token_path = NULL; - opts.bpf_token_fd = -1; - skel = dummy_st_ops_success__open_opts(&opts); - if (!ASSERT_OK_PTR(skel, "obj_neg_token_fd_open")) - goto err_out; - - err = dummy_st_ops_success__load(skel); - dummy_st_ops_success__destroy(skel); - if (!ASSERT_ERR(err, "obj_neg_token_fd_load")) - goto err_out; - - rmdir(TOKEN_BPFFS_CUSTOM); - unsetenv(TOKEN_ENVVAR); - return 0; -err_out: - rmdir(TOKEN_BPFFS_CUSTOM); - unsetenv(TOKEN_ENVVAR); - return -EINVAL; -} - -#define bit(n) (1ULL << (n)) - -void test_token(void) -{ - if (test__start_subtest("map_token")) { - struct bpffs_opts opts = { - .cmds_str = "map_create", - .maps_str = "stack", - }; - - subtest_userns(&opts, userns_map_create); - } - if (test__start_subtest("btf_token")) { - struct bpffs_opts opts = { - .cmds = 1ULL << BPF_BTF_LOAD, - }; - - subtest_userns(&opts, userns_btf_load); - } - if (test__start_subtest("prog_token")) { - struct bpffs_opts opts = { - .cmds_str = "PROG_LOAD", - .progs_str = "XDP", - .attachs_str = "xdp", - }; - - subtest_userns(&opts, userns_prog_load); - } - if (test__start_subtest("obj_priv_map")) { - struct bpffs_opts opts = { - .cmds = bit(BPF_MAP_CREATE), - .maps = bit(BPF_MAP_TYPE_QUEUE), - }; - - subtest_userns(&opts, userns_obj_priv_map); - } - if (test__start_subtest("obj_priv_prog")) { - struct bpffs_opts opts = { - .cmds = bit(BPF_PROG_LOAD), - .progs = bit(BPF_PROG_TYPE_KPROBE), - .attachs = ~0ULL, - }; - - subtest_userns(&opts, userns_obj_priv_prog); - } - if (test__start_subtest("obj_priv_btf_fail")) { - struct bpffs_opts opts = { - /* disallow BTF loading */ - .cmds = bit(BPF_MAP_CREATE) | bit(BPF_PROG_LOAD), - .maps = bit(BPF_MAP_TYPE_STRUCT_OPS), - .progs = bit(BPF_PROG_TYPE_STRUCT_OPS), - .attachs = ~0ULL, - }; - - subtest_userns(&opts, userns_obj_priv_btf_fail); - } - if (test__start_subtest("obj_priv_btf_success")) { - struct bpffs_opts opts = { - /* allow BTF loading */ - .cmds = bit(BPF_BTF_LOAD) | bit(BPF_MAP_CREATE) | bit(BPF_PROG_LOAD), - .maps = bit(BPF_MAP_TYPE_STRUCT_OPS), - .progs = bit(BPF_PROG_TYPE_STRUCT_OPS), - .attachs = ~0ULL, - }; - - subtest_userns(&opts, userns_obj_priv_btf_success); - } - if (test__start_subtest("obj_priv_implicit_token")) { - struct bpffs_opts opts = { - /* allow BTF loading */ - .cmds = bit(BPF_BTF_LOAD) | bit(BPF_MAP_CREATE) | bit(BPF_PROG_LOAD), - .maps = bit(BPF_MAP_TYPE_STRUCT_OPS), - .progs = bit(BPF_PROG_TYPE_STRUCT_OPS), - .attachs = ~0ULL, - }; - - subtest_userns(&opts, userns_obj_priv_implicit_token); - } - if (test__start_subtest("obj_priv_implicit_token_envvar")) { - struct bpffs_opts opts = { - /* allow BTF loading */ - .cmds = bit(BPF_BTF_LOAD) | bit(BPF_MAP_CREATE) | bit(BPF_PROG_LOAD), - .maps = bit(BPF_MAP_TYPE_STRUCT_OPS), - .progs = bit(BPF_PROG_TYPE_STRUCT_OPS), - .attachs = ~0ULL, - }; - - subtest_userns(&opts, userns_obj_priv_implicit_token_envvar); - } -} diff --git a/tools/testing/selftests/bpf/progs/priv_map.c b/tools/testing/selftests/bpf/progs/priv_map.c deleted file mode 100644 index 9085be50f03b..000000000000 --- a/tools/testing/selftests/bpf/progs/priv_map.c +++ /dev/null @@ -1,13 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */ - -#include "vmlinux.h" -#include - -char _license[] SEC("license") = "GPL"; - -struct { - __uint(type, BPF_MAP_TYPE_QUEUE); - __uint(max_entries, 1); - __type(value, __u32); -} priv_map SEC(".maps"); diff --git a/tools/testing/selftests/bpf/progs/priv_prog.c b/tools/testing/selftests/bpf/progs/priv_prog.c deleted file mode 100644 index 3c7b2b618c8a..000000000000 --- a/tools/testing/selftests/bpf/progs/priv_prog.c +++ /dev/null @@ -1,13 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */ - -#include "vmlinux.h" -#include - -char _license[] SEC("license") = "GPL"; - -SEC("kprobe") -int kprobe_prog(void *ctx) -{ - return 1; -} -- cgit v1.2.3 From d028f87517d6775dccff4ddbca2740826f9e53f1 Mon Sep 17 00:00:00 2001 From: Menglong Dong Date: Tue, 19 Dec 2023 21:47:57 +0800 Subject: bpf: make the verifier tracks the "not equal" for regs We can derive some new information for BPF_JNE in regs_refine_cond_op(). Take following code for example: /* The type of "a" is u32 */ if (a > 0 && a < 100) { /* the range of the register for a is [0, 99], not [1, 99], * and will cause the following error: * * invalid zero-sized read * * as a can be 0. */ bpf_skb_store_bytes(skb, xx, xx, a, 0); } In the code above, "a > 0" will be compiled to "jmp xxx if a == 0". In the TRUE branch, the dst_reg will be marked as known to 0. However, in the fallthrough(FALSE) branch, the dst_reg will not be handled, which makes the [min, max] for a is [0, 99], not [1, 99]. For BPF_JNE, we can reduce the range of the dst reg if the src reg is a const and is exactly the edge of the dst reg. Signed-off-by: Menglong Dong Acked-by: Andrii Nakryiko Acked-by: Shung-Hsi Yu Link: https://lore.kernel.org/r/20231219134800.1550388-2-menglong8.dong@gmail.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 38 +++++++++++++++++++++++++++++++++++++- 1 file changed, 37 insertions(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 4ceec8c2a484..df1cae459c77 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14336,7 +14336,43 @@ again: } break; case BPF_JNE: - /* we don't derive any new information for inequality yet */ + if (!is_reg_const(reg2, is_jmp32)) + swap(reg1, reg2); + if (!is_reg_const(reg2, is_jmp32)) + break; + + /* try to recompute the bound of reg1 if reg2 is a const and + * is exactly the edge of reg1. + */ + val = reg_const_value(reg2, is_jmp32); + if (is_jmp32) { + /* u32_min_value is not equal to 0xffffffff at this point, + * because otherwise u32_max_value is 0xffffffff as well, + * in such a case both reg1 and reg2 would be constants, + * jump would be predicted and reg_set_min_max() won't + * be called. + * + * Same reasoning works for all {u,s}{min,max}{32,64} cases + * below. + */ + if (reg1->u32_min_value == (u32)val) + reg1->u32_min_value++; + if (reg1->u32_max_value == (u32)val) + reg1->u32_max_value--; + if (reg1->s32_min_value == (s32)val) + reg1->s32_min_value++; + if (reg1->s32_max_value == (s32)val) + reg1->s32_max_value--; + } else { + if (reg1->umin_value == (u64)val) + reg1->umin_value++; + if (reg1->umax_value == (u64)val) + reg1->umax_value--; + if (reg1->smin_value == (s64)val) + reg1->smin_value++; + if (reg1->smax_value == (s64)val) + reg1->smax_value--; + } break; case BPF_JSET: if (!is_reg_const(reg2, is_jmp32)) -- cgit v1.2.3 From 4ba1d0f23414135e4f426dae4cb5cdc2ce246f89 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 14 Dec 2023 17:13:25 -0800 Subject: bpf: abstract away global subprog arg preparation logic from reg state setup btf_prepare_func_args() is used to understand expectations and restrictions on global subprog arguments. But current implementation is hard to extend, as it intermixes BTF-based func prototype parsing and interpretation logic with setting up register state at subprog entry. Worse still, those registers are not completely set up inside btf_prepare_func_args(), requiring some more logic later in do_check_common(). Like calling mark_reg_unknown() and similar initialization operations. This intermixing of BTF interpretation and register state setup is problematic. First, it causes duplication of BTF parsing logic for global subprog verification (to set up initial state of global subprog) and global subprog call sites analysis (when we need to check that whatever is being passed into global subprog matches expectations), performed in btf_check_subprog_call(). Given we want to extend global func argument with tags later, this duplication is problematic. So refactor btf_prepare_func_args() to do only BTF-based func proto and args parsing, returning high-level argument "expectations" only, with no regard to specifics of register state. I.e., if it's a context argument, instead of setting register state to PTR_TO_CTX, we return ARG_PTR_TO_CTX enum for that argument as "an argument specification" for further processing inside do_check_common(). Similarly for SCALAR arguments, PTR_TO_MEM, etc. This allows to reuse btf_prepare_func_args() in following patches at global subprog call site analysis time. It also keeps register setup code consistently in one place, do_check_common(). Besides all this, we cache this argument specs information inside env->subprog_info, eliminating the need to redo these potentially expensive BTF traversals, especially if BPF program's BTF is big and/or there are lots of global subprog calls. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231215011334.2307144-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 3 +-- include/linux/bpf_verifier.h | 16 ++++++++++++++++ kernel/bpf/btf.c | 38 ++++++++++++++++++++------------------ kernel/bpf/verifier.c | 43 +++++++++++++++++++++++++++---------------- 4 files changed, 64 insertions(+), 36 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 7a8d4c81a39a..c050c82cc9a5 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2470,8 +2470,7 @@ int btf_check_subprog_arg_match(struct bpf_verifier_env *env, int subprog, struct bpf_reg_state *regs); int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog, struct bpf_reg_state *regs); -int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog, - struct bpf_reg_state *reg, u32 *nargs); +int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog); int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *prog, struct btf *btf, const struct btf_type *t); const char *btf_find_decl_tag_value(const struct btf *btf, const struct btf_type *pt, diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index c2819a6579a5..5742e9c0a7b8 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -606,6 +606,13 @@ static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log) #define BPF_MAX_SUBPROGS 256 +struct bpf_subprog_arg_info { + enum bpf_arg_type arg_type; + union { + u32 mem_size; + }; +}; + struct bpf_subprog_info { /* 'start' has to be the first field otherwise find_subprog() won't work */ u32 start; /* insn idx of function entry point */ @@ -617,6 +624,10 @@ struct bpf_subprog_info { bool is_cb: 1; bool is_async_cb: 1; bool is_exception_cb: 1; + bool args_cached: 1; + + u8 arg_cnt; + struct bpf_subprog_arg_info args[MAX_BPF_FUNC_REG_ARGS]; }; struct bpf_verifier_env; @@ -727,6 +738,11 @@ struct bpf_verifier_env { char tmp_str_buf[TMP_STR_BUF_LEN]; }; +static inline struct bpf_subprog_info *subprog_info(struct bpf_verifier_env *env, int subprog) +{ + return &env->subprog_info[subprog]; +} + __printf(2, 0) void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt, va_list args); __printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env, diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index d56433bf8aba..be2104e5f2f5 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6948,16 +6948,17 @@ int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog, return err; } -/* Convert BTF of a function into bpf_reg_state if possible +/* Process BTF of a function to produce high-level expectation of function + * arguments (like ARG_PTR_TO_CTX, or ARG_PTR_TO_MEM, etc). This information + * is cached in subprog info for reuse. * Returns: * EFAULT - there is a verifier bug. Abort verification. * EINVAL - cannot convert BTF. - * 0 - Successfully converted BTF into bpf_reg_state - * (either PTR_TO_CTX or SCALAR_VALUE). + * 0 - Successfully processed BTF and constructed argument expectations. */ -int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog, - struct bpf_reg_state *regs, u32 *arg_cnt) +int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) { + struct bpf_subprog_info *sub = subprog_info(env, subprog); struct bpf_verifier_log *log = &env->log; struct bpf_prog *prog = env->prog; enum bpf_prog_type prog_type = prog->type; @@ -6967,6 +6968,9 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog, u32 i, nargs, btf_id; const char *tname; + if (sub->args_cached) + return 0; + if (!prog->aux->func_info || prog->aux->func_info_aux[subprog].linkage != BTF_FUNC_GLOBAL) { bpf_log(log, "Verifier bug\n"); @@ -6990,10 +6994,6 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog, } tname = btf_name_by_offset(btf, t->name_off); - if (log->level & BPF_LOG_LEVEL) - bpf_log(log, "Validating %s() func#%d...\n", - tname, subprog); - if (prog->aux->func_info_aux[subprog].unreliable) { bpf_log(log, "Verifier bug in function %s()\n", tname); return -EFAULT; @@ -7013,7 +7013,6 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog, tname, nargs, MAX_BPF_FUNC_REG_ARGS); return -EINVAL; } - *arg_cnt = nargs; /* check that function returns int, exception cb also requires this */ t = btf_type_by_id(btf, t->type); while (btf_type_is_modifier(t)) @@ -7028,24 +7027,24 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog, * Only PTR_TO_CTX and SCALAR are supported atm. */ for (i = 0; i < nargs; i++) { - struct bpf_reg_state *reg = ®s[i + 1]; - t = btf_type_by_id(btf, args[i].type); while (btf_type_is_modifier(t)) t = btf_type_by_id(btf, t->type); if (btf_type_is_int(t) || btf_is_any_enum(t)) { - reg->type = SCALAR_VALUE; + sub->args[i].arg_type = ARG_ANYTHING; continue; } if (btf_type_is_ptr(t)) { + u32 mem_size; + if (btf_get_prog_ctx_type(log, btf, t, prog_type, i)) { - reg->type = PTR_TO_CTX; + sub->args[i].arg_type = ARG_PTR_TO_CTX; continue; } t = btf_type_skip_modifiers(btf, t->type, NULL); - ref_t = btf_resolve_size(btf, t, ®->mem_size); + ref_t = btf_resolve_size(btf, t, &mem_size); if (IS_ERR(ref_t)) { bpf_log(log, "arg#%d reference type('%s %s') size cannot be determined: %ld\n", @@ -7054,15 +7053,18 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog, return -EINVAL; } - reg->type = PTR_TO_MEM | PTR_MAYBE_NULL; - reg->id = ++env->id_gen; - + sub->args[i].arg_type = ARG_PTR_TO_MEM_OR_NULL; + sub->args[i].mem_size = mem_size; continue; } bpf_log(log, "Arg#%d type %s in %s() is not supported yet.\n", i, btf_type_str(t), tname); return -EINVAL; } + + sub->arg_cnt = nargs; + sub->args_cached = true; + return 0; } diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index df1cae459c77..6555785b9f63 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -442,11 +442,6 @@ static struct bpf_func_info_aux *subprog_aux(const struct bpf_verifier_env *env, return &env->prog->aux->func_info_aux[subprog]; } -static struct bpf_subprog_info *subprog_info(struct bpf_verifier_env *env, int subprog) -{ - return &env->subprog_info[subprog]; -} - static void mark_subprog_exc_cb(struct bpf_verifier_env *env, int subprog) { struct bpf_subprog_info *info = subprog_info(env, subprog); @@ -19937,34 +19932,50 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog) regs = state->frame[state->curframe]->regs; if (subprog || env->prog->type == BPF_PROG_TYPE_EXT) { - u32 nargs; + struct bpf_subprog_info *sub = subprog_info(env, subprog); + const char *sub_name = subprog_name(env, subprog); + struct bpf_subprog_arg_info *arg; + struct bpf_reg_state *reg; - ret = btf_prepare_func_args(env, subprog, regs, &nargs); + verbose(env, "Validating %s() func#%d...\n", sub_name, subprog); + ret = btf_prepare_func_args(env, subprog); if (ret) goto out; + if (subprog_is_exc_cb(env, subprog)) { state->frame[0]->in_exception_callback_fn = true; /* We have already ensured that the callback returns an integer, just * like all global subprogs. We need to determine it only has a single * scalar argument. */ - if (nargs != 1 || regs[BPF_REG_1].type != SCALAR_VALUE) { + if (sub->arg_cnt != 1 || sub->args[0].arg_type != ARG_ANYTHING) { verbose(env, "exception cb only supports single integer argument\n"); ret = -EINVAL; goto out; } } - for (i = BPF_REG_1; i <= BPF_REG_5; i++) { - if (regs[i].type == PTR_TO_CTX) + for (i = BPF_REG_1; i <= sub->arg_cnt; i++) { + arg = &sub->args[i - BPF_REG_1]; + reg = ®s[i]; + + if (arg->arg_type == ARG_PTR_TO_CTX) { + reg->type = PTR_TO_CTX; mark_reg_known_zero(env, regs, i); - else if (regs[i].type == SCALAR_VALUE) + } else if (arg->arg_type == ARG_ANYTHING) { + reg->type = SCALAR_VALUE; mark_reg_unknown(env, regs, i); - else if (base_type(regs[i].type) == PTR_TO_MEM) { - const u32 mem_size = regs[i].mem_size; - + } else if (base_type(arg->arg_type) == ARG_PTR_TO_MEM) { + reg->type = PTR_TO_MEM; + if (arg->arg_type & PTR_MAYBE_NULL) + reg->type |= PTR_MAYBE_NULL; mark_reg_known_zero(env, regs, i); - regs[i].mem_size = mem_size; - regs[i].id = ++env->id_gen; + reg->mem_size = arg->mem_size; + reg->id = ++env->id_gen; + } else { + WARN_ONCE(1, "BUG: unhandled arg#%d type %d\n", + i - BPF_REG_1, arg->arg_type); + ret = -EFAULT; + goto out; } } } else { -- cgit v1.2.3 From 5eccd2db42d77e3570619c32d39e39bf486607cf Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 14 Dec 2023 17:13:26 -0800 Subject: bpf: reuse btf_prepare_func_args() check for main program BTF validation Instead of btf_check_subprog_arg_match(), use btf_prepare_func_args() logic to validate "trustworthiness" of main BPF program's BTF information, if it is present. We ignored results of original BTF check anyway, often times producing confusing and ominously-sounding "reg type unsupported for arg#0 function" message, which has no apparent effect on program correctness and verification process. All the -EFAULT returning sanity checks are already performed in check_btf_info_early(), so there is zero reason to have this duplication of logic between btf_check_subprog_call() and btf_check_subprog_arg_match(). Dropping btf_check_subprog_arg_match() simplifies btf_check_func_arg_match() further removing `bool processing_call` flag. One subtle bit that was done by btf_check_subprog_arg_match() was potentially marking main program's BTF as unreliable. We do this explicitly now with a dedicated simple check, preserving the original behavior, but now based on well factored btf_prepare_func_args() logic. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231215011334.2307144-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 2 - kernel/bpf/btf.c | 50 ++-------------------- kernel/bpf/verifier.c | 25 ++++++----- tools/testing/selftests/bpf/prog_tests/log_fixup.c | 4 +- .../selftests/bpf/progs/cgrp_kfunc_failure.c | 2 +- .../selftests/bpf/progs/task_kfunc_failure.c | 2 +- 6 files changed, 19 insertions(+), 66 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index c050c82cc9a5..d0d7eff22b8a 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2466,8 +2466,6 @@ int btf_distill_func_proto(struct bpf_verifier_log *log, struct btf_func_model *m); struct bpf_reg_state; -int btf_check_subprog_arg_match(struct bpf_verifier_env *env, int subprog, - struct bpf_reg_state *regs); int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog, struct bpf_reg_state *regs); int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog); diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index be2104e5f2f5..33d9a1c73f6e 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6768,8 +6768,7 @@ int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *pr static int btf_check_func_arg_match(struct bpf_verifier_env *env, const struct btf *btf, u32 func_id, struct bpf_reg_state *regs, - bool ptr_to_mem_ok, - bool processing_call) + bool ptr_to_mem_ok) { enum bpf_prog_type prog_type = resolve_prog_type(env->prog); struct bpf_verifier_log *log = &env->log; @@ -6842,7 +6841,7 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, i, btf_type_str(t)); return -EINVAL; } - } else if (ptr_to_mem_ok && processing_call) { + } else if (ptr_to_mem_ok) { const struct btf_type *resolve_ret; u32 type_size; @@ -6867,55 +6866,12 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, return 0; } -/* Compare BTF of a function declaration with given bpf_reg_state. - * Returns: - * EFAULT - there is a verifier bug. Abort verification. - * EINVAL - there is a type mismatch or BTF is not available. - * 0 - BTF matches with what bpf_reg_state expects. - * Only PTR_TO_CTX and SCALAR_VALUE states are recognized. - */ -int btf_check_subprog_arg_match(struct bpf_verifier_env *env, int subprog, - struct bpf_reg_state *regs) -{ - struct bpf_prog *prog = env->prog; - struct btf *btf = prog->aux->btf; - bool is_global; - u32 btf_id; - int err; - - if (!prog->aux->func_info) - return -EINVAL; - - btf_id = prog->aux->func_info[subprog].type_id; - if (!btf_id) - return -EFAULT; - - if (prog->aux->func_info_aux[subprog].unreliable) - return -EINVAL; - - is_global = prog->aux->func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL; - err = btf_check_func_arg_match(env, btf, btf_id, regs, is_global, false); - - /* Compiler optimizations can remove arguments from static functions - * or mismatched type can be passed into a global function. - * In such cases mark the function as unreliable from BTF point of view. - */ - if (err) - prog->aux->func_info_aux[subprog].unreliable = true; - return err; -} - /* Compare BTF of a function call with given bpf_reg_state. * Returns: * EFAULT - there is a verifier bug. Abort verification. * EINVAL - there is a type mismatch or BTF is not available. * 0 - BTF matches with what bpf_reg_state expects. * Only PTR_TO_CTX and SCALAR_VALUE states are recognized. - * - * NOTE: the code is duplicated from btf_check_subprog_arg_match() - * because btf_check_func_arg_match() is still doing both. Once that - * function is split in 2, we can call from here btf_check_subprog_arg_match() - * first, and then treat the calling part in a new code path. */ int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog, struct bpf_reg_state *regs) @@ -6937,7 +6893,7 @@ int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog, return -EINVAL; is_global = prog->aux->func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL; - err = btf_check_func_arg_match(env, btf, btf_id, regs, is_global, true); + err = btf_check_func_arg_match(env, btf, btf_id, regs, is_global); /* Compiler optimizations can remove arguments from static functions * or mismatched type can be passed into a global function. diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 6555785b9f63..c26e9ab5226c 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -19904,6 +19904,7 @@ static void free_states(struct bpf_verifier_env *env) static int do_check_common(struct bpf_verifier_env *env, int subprog) { bool pop_log = !(env->log.level & BPF_LOG_LEVEL2); + struct bpf_subprog_info *sub = subprog_info(env, subprog); struct bpf_verifier_state *state; struct bpf_reg_state *regs; int ret, i; @@ -19930,9 +19931,9 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog) state->first_insn_idx = env->subprog_info[subprog].start; state->last_insn_idx = -1; + regs = state->frame[state->curframe]->regs; if (subprog || env->prog->type == BPF_PROG_TYPE_EXT) { - struct bpf_subprog_info *sub = subprog_info(env, subprog); const char *sub_name = subprog_name(env, subprog); struct bpf_subprog_arg_info *arg; struct bpf_reg_state *reg; @@ -19979,21 +19980,19 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog) } } } else { + /* if main BPF program has associated BTF info, validate that + * it's matching expected signature, and otherwise mark BTF + * info for main program as unreliable + */ + if (env->prog->aux->func_info_aux) { + ret = btf_prepare_func_args(env, 0); + if (ret || sub->arg_cnt != 1 || sub->args[0].arg_type != ARG_PTR_TO_CTX) + env->prog->aux->func_info_aux[0].unreliable = true; + } + /* 1st arg to a function */ regs[BPF_REG_1].type = PTR_TO_CTX; mark_reg_known_zero(env, regs, BPF_REG_1); - ret = btf_check_subprog_arg_match(env, subprog, regs); - if (ret == -EFAULT) - /* unlikely verifier bug. abort. - * ret == 0 and ret < 0 are sadly acceptable for - * main() function due to backward compatibility. - * Like socket filter program may be written as: - * int bpf_prog(struct pt_regs *ctx) - * and never dereference that ctx in the program. - * 'struct pt_regs' is a type mismatch for socket - * filter that should be using 'struct __sk_buff'. - */ - goto out; } ret = do_check(env); diff --git a/tools/testing/selftests/bpf/prog_tests/log_fixup.c b/tools/testing/selftests/bpf/prog_tests/log_fixup.c index effd78b2a657..7a3fa2ff567b 100644 --- a/tools/testing/selftests/bpf/prog_tests/log_fixup.c +++ b/tools/testing/selftests/bpf/prog_tests/log_fixup.c @@ -169,9 +169,9 @@ void test_log_fixup(void) if (test__start_subtest("bad_core_relo_trunc_none")) bad_core_relo(0, TRUNC_NONE /* full buf */); if (test__start_subtest("bad_core_relo_trunc_partial")) - bad_core_relo(300, TRUNC_PARTIAL /* truncate original log a bit */); + bad_core_relo(280, TRUNC_PARTIAL /* truncate original log a bit */); if (test__start_subtest("bad_core_relo_trunc_full")) - bad_core_relo(210, TRUNC_FULL /* truncate also libbpf's message patch */); + bad_core_relo(220, TRUNC_FULL /* truncate also libbpf's message patch */); if (test__start_subtest("bad_core_relo_subprog")) bad_core_relo_subprog(); if (test__start_subtest("missing_map")) diff --git a/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c b/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c index 0fa564a5cc5b..9fe9c4a4e8f6 100644 --- a/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c +++ b/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c @@ -78,7 +78,7 @@ int BPF_PROG(cgrp_kfunc_acquire_fp, struct cgroup *cgrp, const char *path) } SEC("kretprobe/cgroup_destroy_locked") -__failure __msg("reg type unsupported for arg#0 function") +__failure __msg("calling kernel function bpf_cgroup_acquire is not allowed") int BPF_PROG(cgrp_kfunc_acquire_unsafe_kretprobe, struct cgroup *cgrp) { struct cgroup *acquired; diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_failure.c b/tools/testing/selftests/bpf/progs/task_kfunc_failure.c index dcdea3127086..ad88a3796ddf 100644 --- a/tools/testing/selftests/bpf/progs/task_kfunc_failure.c +++ b/tools/testing/selftests/bpf/progs/task_kfunc_failure.c @@ -248,7 +248,7 @@ int BPF_PROG(task_kfunc_from_pid_no_null_check, struct task_struct *task, u64 cl } SEC("lsm/task_free") -__failure __msg("reg type unsupported for arg#0 function") +__failure __msg("R1 must be a rcu pointer") int BPF_PROG(task_kfunc_from_lsm_task_free, struct task_struct *task) { struct task_struct *acquired; -- cgit v1.2.3 From e26080d0da87f20222ca6712b65f95a856fadee0 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 14 Dec 2023 17:13:27 -0800 Subject: bpf: prepare btf_prepare_func_args() for handling static subprogs Generalize btf_prepare_func_args() to support both global and static subprogs. We are going to utilize this property in the next patch, reusing btf_prepare_func_args() for subprog call logic instead of reparsing BTF information in a completely separate implementation. btf_prepare_func_args() now detects whether subprog is global or static makes slight logic adjustments for static func cases, like not failing fatally (-EFAULT) for conditions that are allowable for static subprogs. Somewhat subtle (but major!) difference is the handling of pointer arguments. Both global and static functions need to handle special context arguments (which are pointers to predefined type names), but static subprogs give up on any other pointers, falling back to marking subprog as "unreliable", disabling the use of BTF type information altogether. For global functions, though, we are assuming that such pointers to unrecognized types are just pointers to fixed-sized memory region (or error out if size cannot be established, like for `void *` pointers). This patch accommodates these small differences and sets up a stage for refactoring in the next patch, eliminating a separate BTF-based parsing logic in btf_check_func_arg_match(). Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231215011334.2307144-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf_verifier.h | 5 +++++ kernel/bpf/btf.c | 18 +++++++++--------- kernel/bpf/verifier.c | 5 ----- 3 files changed, 14 insertions(+), 14 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 5742e9c0a7b8..d3ea9ef04767 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -738,6 +738,11 @@ struct bpf_verifier_env { char tmp_str_buf[TMP_STR_BUF_LEN]; }; +static inline struct bpf_func_info_aux *subprog_aux(struct bpf_verifier_env *env, int subprog) +{ + return &env->prog->aux->func_info_aux[subprog]; +} + static inline struct bpf_subprog_info *subprog_info(struct bpf_verifier_env *env, int subprog) { return &env->subprog_info[subprog]; diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 33d9a1c73f6e..d321340e16f1 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6914,6 +6914,7 @@ int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog, */ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) { + bool is_global = subprog_aux(env, subprog)->linkage == BTF_FUNC_GLOBAL; struct bpf_subprog_info *sub = subprog_info(env, subprog); struct bpf_verifier_log *log = &env->log; struct bpf_prog *prog = env->prog; @@ -6927,14 +6928,15 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) if (sub->args_cached) return 0; - if (!prog->aux->func_info || - prog->aux->func_info_aux[subprog].linkage != BTF_FUNC_GLOBAL) { + if (!prog->aux->func_info) { bpf_log(log, "Verifier bug\n"); return -EFAULT; } btf_id = prog->aux->func_info[subprog].type_id; if (!btf_id) { + if (!is_global) /* not fatal for static funcs */ + return -EINVAL; bpf_log(log, "Global functions need valid BTF\n"); return -EFAULT; } @@ -6990,16 +6992,14 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) sub->args[i].arg_type = ARG_ANYTHING; continue; } - if (btf_type_is_ptr(t)) { + if (btf_type_is_ptr(t) && btf_get_prog_ctx_type(log, btf, t, prog_type, i)) { + sub->args[i].arg_type = ARG_PTR_TO_CTX; + continue; + } + if (is_global && btf_type_is_ptr(t)) { u32 mem_size; - if (btf_get_prog_ctx_type(log, btf, t, prog_type, i)) { - sub->args[i].arg_type = ARG_PTR_TO_CTX; - continue; - } - t = btf_type_skip_modifiers(btf, t->type, NULL); - ref_t = btf_resolve_size(btf, t, &mem_size); if (IS_ERR(ref_t)) { bpf_log(log, diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index c26e9ab5226c..6c9ecb86a8d9 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -437,11 +437,6 @@ static const char *subprog_name(const struct bpf_verifier_env *env, int subprog) return btf_type_name(env->prog->aux->btf, info->type_id); } -static struct bpf_func_info_aux *subprog_aux(const struct bpf_verifier_env *env, int subprog) -{ - return &env->prog->aux->func_info_aux[subprog]; -} - static void mark_subprog_exc_cb(struct bpf_verifier_env *env, int subprog) { struct bpf_subprog_info *info = subprog_info(env, subprog); -- cgit v1.2.3 From c5a7244759b1eeacc59d0426fb73859afa942d0d Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 14 Dec 2023 17:13:28 -0800 Subject: bpf: move subprog call logic back to verifier.c Subprog call logic in btf_check_subprog_call() currently has both a lot of BTF parsing logic (which is, presumably, what justified putting it into btf.c), but also a bunch of register state checks, some of each utilize deep verifier logic helpers, necessarily exported from verifier.c: check_ptr_off_reg(), check_func_arg_reg_off(), and check_mem_reg(). Going forward, btf_check_subprog_call() will have a minimum of BTF-related logic, but will get more internal verifier logic related to register state manipulation. So move it into verifier.c to minimize amount of verifier-specific logic exposed to btf.c. We do this move before refactoring btf_check_func_arg_match() to preserve as much history post-refactoring as possible. No functional changes. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231215011334.2307144-5-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 2 - include/linux/bpf_verifier.h | 8 --- kernel/bpf/btf.c | 139 --------------------------------------- kernel/bpf/verifier.c | 153 +++++++++++++++++++++++++++++++++++++++++-- 4 files changed, 146 insertions(+), 156 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index d0d7eff22b8a..7671530d6e4e 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2466,8 +2466,6 @@ int btf_distill_func_proto(struct bpf_verifier_log *log, struct btf_func_model *m); struct bpf_reg_state; -int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog, - struct bpf_reg_state *regs); int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog); int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *prog, struct btf *btf, const struct btf_type *t); diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index d3ea9ef04767..d07d857ca67f 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -785,14 +785,6 @@ bpf_prog_offload_replace_insn(struct bpf_verifier_env *env, u32 off, void bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt); -int check_ptr_off_reg(struct bpf_verifier_env *env, - const struct bpf_reg_state *reg, int regno); -int check_func_arg_reg_off(struct bpf_verifier_env *env, - const struct bpf_reg_state *reg, int regno, - enum bpf_arg_type arg_type); -int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg, - u32 regno, u32 mem_size); - /* this lives here instead of in bpf.h because it needs to dereference tgt_prog */ static inline u64 bpf_trampoline_compute_key(const struct bpf_prog *tgt_prog, struct btf *btf, u32 btf_id) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index d321340e16f1..341811bcca53 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6765,145 +6765,6 @@ int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *pr return btf_check_func_type_match(log, btf1, t1, btf2, t2); } -static int btf_check_func_arg_match(struct bpf_verifier_env *env, - const struct btf *btf, u32 func_id, - struct bpf_reg_state *regs, - bool ptr_to_mem_ok) -{ - enum bpf_prog_type prog_type = resolve_prog_type(env->prog); - struct bpf_verifier_log *log = &env->log; - const char *func_name, *ref_tname; - const struct btf_type *t, *ref_t; - const struct btf_param *args; - u32 i, nargs, ref_id; - int ret; - - t = btf_type_by_id(btf, func_id); - if (!t || !btf_type_is_func(t)) { - /* These checks were already done by the verifier while loading - * struct bpf_func_info or in add_kfunc_call(). - */ - bpf_log(log, "BTF of func_id %u doesn't point to KIND_FUNC\n", - func_id); - return -EFAULT; - } - func_name = btf_name_by_offset(btf, t->name_off); - - t = btf_type_by_id(btf, t->type); - if (!t || !btf_type_is_func_proto(t)) { - bpf_log(log, "Invalid BTF of func %s\n", func_name); - return -EFAULT; - } - args = (const struct btf_param *)(t + 1); - nargs = btf_type_vlen(t); - if (nargs > MAX_BPF_FUNC_REG_ARGS) { - bpf_log(log, "Function %s has %d > %d args\n", func_name, nargs, - MAX_BPF_FUNC_REG_ARGS); - return -EINVAL; - } - - /* check that BTF function arguments match actual types that the - * verifier sees. - */ - for (i = 0; i < nargs; i++) { - enum bpf_arg_type arg_type = ARG_DONTCARE; - u32 regno = i + 1; - struct bpf_reg_state *reg = ®s[regno]; - - t = btf_type_skip_modifiers(btf, args[i].type, NULL); - if (btf_type_is_scalar(t)) { - if (reg->type == SCALAR_VALUE) - continue; - bpf_log(log, "R%d is not a scalar\n", regno); - return -EINVAL; - } - - if (!btf_type_is_ptr(t)) { - bpf_log(log, "Unrecognized arg#%d type %s\n", - i, btf_type_str(t)); - return -EINVAL; - } - - ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id); - ref_tname = btf_name_by_offset(btf, ref_t->name_off); - - ret = check_func_arg_reg_off(env, reg, regno, arg_type); - if (ret < 0) - return ret; - - if (btf_get_prog_ctx_type(log, btf, t, prog_type, i)) { - /* If function expects ctx type in BTF check that caller - * is passing PTR_TO_CTX. - */ - if (reg->type != PTR_TO_CTX) { - bpf_log(log, - "arg#%d expected pointer to ctx, but got %s\n", - i, btf_type_str(t)); - return -EINVAL; - } - } else if (ptr_to_mem_ok) { - const struct btf_type *resolve_ret; - u32 type_size; - - resolve_ret = btf_resolve_size(btf, ref_t, &type_size); - if (IS_ERR(resolve_ret)) { - bpf_log(log, - "arg#%d reference type('%s %s') size cannot be determined: %ld\n", - i, btf_type_str(ref_t), ref_tname, - PTR_ERR(resolve_ret)); - return -EINVAL; - } - - if (check_mem_reg(env, reg, regno, type_size)) - return -EINVAL; - } else { - bpf_log(log, "reg type unsupported for arg#%d function %s#%d\n", i, - func_name, func_id); - return -EINVAL; - } - } - - return 0; -} - -/* Compare BTF of a function call with given bpf_reg_state. - * Returns: - * EFAULT - there is a verifier bug. Abort verification. - * EINVAL - there is a type mismatch or BTF is not available. - * 0 - BTF matches with what bpf_reg_state expects. - * Only PTR_TO_CTX and SCALAR_VALUE states are recognized. - */ -int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog, - struct bpf_reg_state *regs) -{ - struct bpf_prog *prog = env->prog; - struct btf *btf = prog->aux->btf; - bool is_global; - u32 btf_id; - int err; - - if (!prog->aux->func_info) - return -EINVAL; - - btf_id = prog->aux->func_info[subprog].type_id; - if (!btf_id) - return -EFAULT; - - if (prog->aux->func_info_aux[subprog].unreliable) - return -EINVAL; - - is_global = prog->aux->func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL; - err = btf_check_func_arg_match(env, btf, btf_id, regs, is_global); - - /* Compiler optimizations can remove arguments from static functions - * or mismatched type can be passed into a global function. - * In such cases mark the function as unreliable from BTF point of view. - */ - if (err) - prog->aux->func_info_aux[subprog].unreliable = true; - return err; -} - /* Process BTF of a function to produce high-level expectation of function * arguments (like ARG_PTR_TO_CTX, or ARG_PTR_TO_MEM, etc). This information * is cached in subprog info for reuse. diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 6c9ecb86a8d9..f48e49f2d482 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5127,8 +5127,8 @@ static int __check_ptr_off_reg(struct bpf_verifier_env *env, return 0; } -int check_ptr_off_reg(struct bpf_verifier_env *env, - const struct bpf_reg_state *reg, int regno) +static int check_ptr_off_reg(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, int regno) { return __check_ptr_off_reg(env, reg, regno, false); } @@ -7300,8 +7300,8 @@ static int check_mem_size_reg(struct bpf_verifier_env *env, return err; } -int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg, - u32 regno, u32 mem_size) +static int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg, + u32 regno, u32 mem_size) { bool may_be_null = type_may_be_null(reg->type); struct bpf_reg_state saved_reg; @@ -8286,9 +8286,9 @@ reg_find_field_offset(const struct bpf_reg_state *reg, s32 off, u32 fields) return field; } -int check_func_arg_reg_off(struct bpf_verifier_env *env, - const struct bpf_reg_state *reg, int regno, - enum bpf_arg_type arg_type) +static int check_func_arg_reg_off(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, int regno, + enum bpf_arg_type arg_type) { u32 type = reg->type; @@ -9249,6 +9249,145 @@ err_out: return err; } +static int btf_check_func_arg_match(struct bpf_verifier_env *env, + const struct btf *btf, u32 func_id, + struct bpf_reg_state *regs, + bool ptr_to_mem_ok) +{ + enum bpf_prog_type prog_type = resolve_prog_type(env->prog); + struct bpf_verifier_log *log = &env->log; + const char *func_name, *ref_tname; + const struct btf_type *t, *ref_t; + const struct btf_param *args; + u32 i, nargs, ref_id; + int ret; + + t = btf_type_by_id(btf, func_id); + if (!t || !btf_type_is_func(t)) { + /* These checks were already done by the verifier while loading + * struct bpf_func_info or in add_kfunc_call(). + */ + bpf_log(log, "BTF of func_id %u doesn't point to KIND_FUNC\n", + func_id); + return -EFAULT; + } + func_name = btf_name_by_offset(btf, t->name_off); + + t = btf_type_by_id(btf, t->type); + if (!t || !btf_type_is_func_proto(t)) { + bpf_log(log, "Invalid BTF of func %s\n", func_name); + return -EFAULT; + } + args = (const struct btf_param *)(t + 1); + nargs = btf_type_vlen(t); + if (nargs > MAX_BPF_FUNC_REG_ARGS) { + bpf_log(log, "Function %s has %d > %d args\n", func_name, nargs, + MAX_BPF_FUNC_REG_ARGS); + return -EINVAL; + } + + /* check that BTF function arguments match actual types that the + * verifier sees. + */ + for (i = 0; i < nargs; i++) { + enum bpf_arg_type arg_type = ARG_DONTCARE; + u32 regno = i + 1; + struct bpf_reg_state *reg = ®s[regno]; + + t = btf_type_skip_modifiers(btf, args[i].type, NULL); + if (btf_type_is_scalar(t)) { + if (reg->type == SCALAR_VALUE) + continue; + bpf_log(log, "R%d is not a scalar\n", regno); + return -EINVAL; + } + + if (!btf_type_is_ptr(t)) { + bpf_log(log, "Unrecognized arg#%d type %s\n", + i, btf_type_str(t)); + return -EINVAL; + } + + ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id); + ref_tname = btf_name_by_offset(btf, ref_t->name_off); + + ret = check_func_arg_reg_off(env, reg, regno, arg_type); + if (ret < 0) + return ret; + + if (btf_get_prog_ctx_type(log, btf, t, prog_type, i)) { + /* If function expects ctx type in BTF check that caller + * is passing PTR_TO_CTX. + */ + if (reg->type != PTR_TO_CTX) { + bpf_log(log, + "arg#%d expected pointer to ctx, but got %s\n", + i, btf_type_str(t)); + return -EINVAL; + } + } else if (ptr_to_mem_ok) { + const struct btf_type *resolve_ret; + u32 type_size; + + resolve_ret = btf_resolve_size(btf, ref_t, &type_size); + if (IS_ERR(resolve_ret)) { + bpf_log(log, + "arg#%d reference type('%s %s') size cannot be determined: %ld\n", + i, btf_type_str(ref_t), ref_tname, + PTR_ERR(resolve_ret)); + return -EINVAL; + } + + if (check_mem_reg(env, reg, regno, type_size)) + return -EINVAL; + } else { + bpf_log(log, "reg type unsupported for arg#%d function %s#%d\n", i, + func_name, func_id); + return -EINVAL; + } + } + + return 0; +} + +/* Compare BTF of a function call with given bpf_reg_state. + * Returns: + * EFAULT - there is a verifier bug. Abort verification. + * EINVAL - there is a type mismatch or BTF is not available. + * 0 - BTF matches with what bpf_reg_state expects. + * Only PTR_TO_CTX and SCALAR_VALUE states are recognized. + */ +static int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog, + struct bpf_reg_state *regs) +{ + struct bpf_prog *prog = env->prog; + struct btf *btf = prog->aux->btf; + bool is_global; + u32 btf_id; + int err; + + if (!prog->aux->func_info) + return -EINVAL; + + btf_id = prog->aux->func_info[subprog].type_id; + if (!btf_id) + return -EFAULT; + + if (prog->aux->func_info_aux[subprog].unreliable) + return -EINVAL; + + is_global = prog->aux->func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL; + err = btf_check_func_arg_match(env, btf, btf_id, regs, is_global); + + /* Compiler optimizations can remove arguments from static functions + * or mismatched type can be passed into a global function. + * In such cases mark the function as unreliable from BTF point of view. + */ + if (err) + prog->aux->func_info_aux[subprog].unreliable = true; + return err; +} + static int push_callback_call(struct bpf_verifier_env *env, struct bpf_insn *insn, int insn_idx, int subprog, set_callee_state_fn set_callee_state_cb) -- cgit v1.2.3 From f18c3d88deedf0defc3e4800341cc7bcaaabcdf9 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 14 Dec 2023 17:13:29 -0800 Subject: bpf: reuse subprog argument parsing logic for subprog call checks Remove duplicated BTF parsing logic when it comes to subprog call check. Instead, use (potentially cached) results of btf_prepare_func_args() to abstract away expectations of each subprog argument in generic terms (e.g., "this is pointer to context", or "this is a pointer to memory of size X"), and then use those simple high-level argument type expectations to validate actual register states to check if they match expectations. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231215011334.2307144-6-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 110 ++++++--------------- .../selftests/bpf/progs/test_global_func5.c | 2 +- 2 files changed, 31 insertions(+), 81 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f48e49f2d482..3c9e6d0d77d6 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9249,101 +9249,54 @@ err_out: return err; } -static int btf_check_func_arg_match(struct bpf_verifier_env *env, - const struct btf *btf, u32 func_id, - struct bpf_reg_state *regs, - bool ptr_to_mem_ok) +static int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog, + const struct btf *btf, + struct bpf_reg_state *regs) { - enum bpf_prog_type prog_type = resolve_prog_type(env->prog); + struct bpf_subprog_info *sub = subprog_info(env, subprog); struct bpf_verifier_log *log = &env->log; - const char *func_name, *ref_tname; - const struct btf_type *t, *ref_t; - const struct btf_param *args; - u32 i, nargs, ref_id; + u32 i; int ret; - t = btf_type_by_id(btf, func_id); - if (!t || !btf_type_is_func(t)) { - /* These checks were already done by the verifier while loading - * struct bpf_func_info or in add_kfunc_call(). - */ - bpf_log(log, "BTF of func_id %u doesn't point to KIND_FUNC\n", - func_id); - return -EFAULT; - } - func_name = btf_name_by_offset(btf, t->name_off); - - t = btf_type_by_id(btf, t->type); - if (!t || !btf_type_is_func_proto(t)) { - bpf_log(log, "Invalid BTF of func %s\n", func_name); - return -EFAULT; - } - args = (const struct btf_param *)(t + 1); - nargs = btf_type_vlen(t); - if (nargs > MAX_BPF_FUNC_REG_ARGS) { - bpf_log(log, "Function %s has %d > %d args\n", func_name, nargs, - MAX_BPF_FUNC_REG_ARGS); - return -EINVAL; - } + ret = btf_prepare_func_args(env, subprog); + if (ret) + return ret; /* check that BTF function arguments match actual types that the * verifier sees. */ - for (i = 0; i < nargs; i++) { - enum bpf_arg_type arg_type = ARG_DONTCARE; + for (i = 0; i < sub->arg_cnt; i++) { u32 regno = i + 1; struct bpf_reg_state *reg = ®s[regno]; + struct bpf_subprog_arg_info *arg = &sub->args[i]; - t = btf_type_skip_modifiers(btf, args[i].type, NULL); - if (btf_type_is_scalar(t)) { - if (reg->type == SCALAR_VALUE) - continue; - bpf_log(log, "R%d is not a scalar\n", regno); - return -EINVAL; - } - - if (!btf_type_is_ptr(t)) { - bpf_log(log, "Unrecognized arg#%d type %s\n", - i, btf_type_str(t)); - return -EINVAL; - } - - ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id); - ref_tname = btf_name_by_offset(btf, ref_t->name_off); - - ret = check_func_arg_reg_off(env, reg, regno, arg_type); - if (ret < 0) - return ret; - - if (btf_get_prog_ctx_type(log, btf, t, prog_type, i)) { + if (arg->arg_type == ARG_ANYTHING) { + if (reg->type != SCALAR_VALUE) { + bpf_log(log, "R%d is not a scalar\n", regno); + return -EINVAL; + } + } else if (arg->arg_type == ARG_PTR_TO_CTX) { + ret = check_func_arg_reg_off(env, reg, regno, ARG_DONTCARE); + if (ret < 0) + return ret; /* If function expects ctx type in BTF check that caller * is passing PTR_TO_CTX. */ if (reg->type != PTR_TO_CTX) { - bpf_log(log, - "arg#%d expected pointer to ctx, but got %s\n", - i, btf_type_str(t)); - return -EINVAL; - } - } else if (ptr_to_mem_ok) { - const struct btf_type *resolve_ret; - u32 type_size; - - resolve_ret = btf_resolve_size(btf, ref_t, &type_size); - if (IS_ERR(resolve_ret)) { - bpf_log(log, - "arg#%d reference type('%s %s') size cannot be determined: %ld\n", - i, btf_type_str(ref_t), ref_tname, - PTR_ERR(resolve_ret)); + bpf_log(log, "arg#%d expects pointer to ctx\n", i); return -EINVAL; } + } else if (base_type(arg->arg_type) == ARG_PTR_TO_MEM) { + ret = check_func_arg_reg_off(env, reg, regno, ARG_DONTCARE); + if (ret < 0) + return ret; - if (check_mem_reg(env, reg, regno, type_size)) + if (check_mem_reg(env, reg, regno, arg->mem_size)) return -EINVAL; } else { - bpf_log(log, "reg type unsupported for arg#%d function %s#%d\n", i, - func_name, func_id); - return -EINVAL; + bpf_log(log, "verifier bug: unrecognized arg#%d type %d\n", + i, arg->arg_type); + return -EFAULT; } } @@ -9358,11 +9311,10 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, * Only PTR_TO_CTX and SCALAR_VALUE states are recognized. */ static int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog, - struct bpf_reg_state *regs) + struct bpf_reg_state *regs) { struct bpf_prog *prog = env->prog; struct btf *btf = prog->aux->btf; - bool is_global; u32 btf_id; int err; @@ -9376,9 +9328,7 @@ static int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog, if (prog->aux->func_info_aux[subprog].unreliable) return -EINVAL; - is_global = prog->aux->func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL; - err = btf_check_func_arg_match(env, btf, btf_id, regs, is_global); - + err = btf_check_func_arg_match(env, subprog, btf, regs); /* Compiler optimizations can remove arguments from static functions * or mismatched type can be passed into a global function. * In such cases mark the function as unreliable from BTF point of view. diff --git a/tools/testing/selftests/bpf/progs/test_global_func5.c b/tools/testing/selftests/bpf/progs/test_global_func5.c index cc55aedaf82d..257c0569ff98 100644 --- a/tools/testing/selftests/bpf/progs/test_global_func5.c +++ b/tools/testing/selftests/bpf/progs/test_global_func5.c @@ -26,7 +26,7 @@ int f3(int val, struct __sk_buff *skb) } SEC("tc") -__failure __msg("expected pointer to ctx, but got PTR") +__failure __msg("expects pointer to ctx") int global_func5(struct __sk_buff *skb) { return f1(skb) + f2(2, skb) + f3(3, skb); -- cgit v1.2.3 From 94e1c70a34523b5e1529e4ec508316acc6a26a2b Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 14 Dec 2023 17:13:30 -0800 Subject: bpf: support 'arg:xxx' btf_decl_tag-based hints for global subprog args Add support for annotating global BPF subprog arguments to provide more information about expected semantics of the argument. Currently, verifier relies purely on argument's BTF type information, and supports three general use cases: scalar, pointer-to-context, and pointer-to-fixed-size-memory. Scalar and pointer-to-fixed-mem work well in practice and are quite natural to use. But pointer-to-context is a bit problematic, as typical BPF users don't realize that they need to use a special type name to signal to verifier that argument is not just some pointer, but actually a PTR_TO_CTX. Further, even if users do know which type to use, it is limiting in situations where the same BPF program logic is used across few different program types. Common case is kprobes, tracepoints, and perf_event programs having a helper to send some data over BPF perf buffer. bpf_perf_event_output() requires `ctx` argument, and so it's quite cumbersome to share such global subprog across few BPF programs of different types, necessitating extra static subprog that is context type-agnostic. Long story short, there is a need to go beyond types and allow users to add hints to global subprog arguments to define expectations. This patch adds such support for two initial special tags: - pointer to context; - non-null qualifier for generic pointer arguments. All of the above came up in practice already and seem generally useful additions. Non-null qualifier is an often requested feature, which currently has to be worked around by having unnecessary NULL checks inside subprogs even if we know that arguments are never NULL. Pointer to context was discussed earlier. As for implementation, we utilize btf_decl_tag attribute and set up an "arg:xxx" convention to specify argument hint. As such: - btf_decl_tag("arg:ctx") is a PTR_TO_CTX hint; - btf_decl_tag("arg:nonnull") marks pointer argument as not allowed to be NULL, making NULL check inside global subprog unnecessary. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231215011334.2307144-7-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/btf.c | 44 ++++++++++++++++++++++++++++++++++++++------ kernel/bpf/verifier.c | 5 ++++- 2 files changed, 42 insertions(+), 7 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 341811bcca53..c0fc8977be97 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6782,7 +6782,7 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) enum bpf_prog_type prog_type = prog->type; struct btf *btf = prog->aux->btf; const struct btf_param *args; - const struct btf_type *t, *ref_t; + const struct btf_type *t, *ref_t, *fn_t; u32 i, nargs, btf_id; const char *tname; @@ -6802,8 +6802,8 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) return -EFAULT; } - t = btf_type_by_id(btf, btf_id); - if (!t || !btf_type_is_func(t)) { + fn_t = btf_type_by_id(btf, btf_id); + if (!fn_t || !btf_type_is_func(fn_t)) { /* These checks were already done by the verifier while loading * struct bpf_func_info */ @@ -6811,7 +6811,7 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) subprog); return -EFAULT; } - tname = btf_name_by_offset(btf, t->name_off); + tname = btf_name_by_offset(btf, fn_t->name_off); if (prog->aux->func_info_aux[subprog].unreliable) { bpf_log(log, "Verifier bug in function %s()\n", tname); @@ -6820,7 +6820,7 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) if (prog_type == BPF_PROG_TYPE_EXT) prog_type = prog->aux->dst_prog->type; - t = btf_type_by_id(btf, t->type); + t = btf_type_by_id(btf, fn_t->type); if (!t || !btf_type_is_func_proto(t)) { bpf_log(log, "Invalid type of function %s()\n", tname); return -EFAULT; @@ -6846,7 +6846,35 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) * Only PTR_TO_CTX and SCALAR are supported atm. */ for (i = 0; i < nargs; i++) { + bool is_nonnull = false; + const char *tag; + t = btf_type_by_id(btf, args[i].type); + + tag = btf_find_decl_tag_value(btf, fn_t, i, "arg:"); + if (IS_ERR(tag) && PTR_ERR(tag) == -ENOENT) { + tag = NULL; + } else if (IS_ERR(tag)) { + bpf_log(log, "arg#%d type's tag fetching failure: %ld\n", i, PTR_ERR(tag)); + return PTR_ERR(tag); + } + /* 'arg:' decl_tag takes precedence over derivation of + * register type from BTF type itself + */ + if (tag) { + /* disallow arg tags in static subprogs */ + if (!is_global) { + bpf_log(log, "arg#%d type tag is not supported in static functions\n", i); + return -EOPNOTSUPP; + } + if (strcmp(tag, "ctx") == 0) { + sub->args[i].arg_type = ARG_PTR_TO_CTX; + continue; + } + if (strcmp(tag, "nonnull") == 0) + is_nonnull = true; + } + while (btf_type_is_modifier(t)) t = btf_type_by_id(btf, t->type); if (btf_type_is_int(t) || btf_is_any_enum(t)) { @@ -6870,10 +6898,14 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) return -EINVAL; } - sub->args[i].arg_type = ARG_PTR_TO_MEM_OR_NULL; + sub->args[i].arg_type = is_nonnull ? ARG_PTR_TO_MEM : ARG_PTR_TO_MEM_OR_NULL; sub->args[i].mem_size = mem_size; continue; } + if (is_nonnull) { + bpf_log(log, "arg#%d marked as non-null, but is not a pointer type\n", i); + return -EINVAL; + } bpf_log(log, "Arg#%d type %s in %s() is not supported yet.\n", i, btf_type_str(t), tname); return -EINVAL; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 3c9e6d0d77d6..4caabfdc15aa 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9290,9 +9290,12 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog, ret = check_func_arg_reg_off(env, reg, regno, ARG_DONTCARE); if (ret < 0) return ret; - if (check_mem_reg(env, reg, regno, arg->mem_size)) return -EINVAL; + if (!(arg->arg_type & PTR_MAYBE_NULL) && (reg->type & PTR_MAYBE_NULL)) { + bpf_log(log, "arg#%d is expected to be non-NULL\n", i); + return -EINVAL; + } } else { bpf_log(log, "verifier bug: unrecognized arg#%d type %d\n", i, arg->arg_type); -- cgit v1.2.3 From a64bfe618665ea9c722f922cba8c6e3234eac5ac Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 14 Dec 2023 17:13:31 -0800 Subject: bpf: add support for passing dynptr pointer to global subprog Add ability to pass a pointer to dynptr into global functions. This allows to have global subprogs that accept and work with generic dynptrs that are created by caller. Dynptr argument is detected based on the name of a struct type, if it's "bpf_dynptr", it's assumed to be a proper dynptr pointer. Both actual struct and forward struct declaration types are supported. This is conceptually exactly the same semantics as bpf_user_ringbuf_drain()'s use of dynptr to pass a variable-sized pointer to ringbuf record. So we heavily rely on CONST_PTR_TO_DYNPTR bits of already existing logic in the verifier. During global subprog validation, we mark such CONST_PTR_TO_DYNPTR as having LOCAL type, as that's the most unassuming type of dynptr and it doesn't have any special helpers that can try to free or acquire extra references (unlike skb, xdp, or ringbuf dynptr). So that seems like a safe "choice" to make from correctness standpoint. It's still possible to pass any type of dynptr to such subprog, though, because generic dynptr helpers, like getting data/slice pointers, read/write memory copying routines, dynptr adjustment and getter routines all work correctly with any type of dynptr. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231215011334.2307144-8-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/btf.c | 23 +++++++++++++++++++++++ kernel/bpf/verifier.c | 7 +++++++ 2 files changed, 30 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index c0fc8977be97..51e8b4bee0c8 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6765,6 +6765,25 @@ int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *pr return btf_check_func_type_match(log, btf1, t1, btf2, t2); } +static bool btf_is_dynptr_ptr(const struct btf *btf, const struct btf_type *t) +{ + const char *name; + + t = btf_type_by_id(btf, t->type); /* skip PTR */ + + while (btf_type_is_modifier(t)) + t = btf_type_by_id(btf, t->type); + + /* allow either struct or struct forward declaration */ + if (btf_type_is_struct(t) || + (btf_type_is_fwd(t) && btf_type_kflag(t) == 0)) { + name = btf_str_by_offset(btf, t->name_off); + return name && strcmp(name, "bpf_dynptr") == 0; + } + + return false; +} + /* Process BTF of a function to produce high-level expectation of function * arguments (like ARG_PTR_TO_CTX, or ARG_PTR_TO_MEM, etc). This information * is cached in subprog info for reuse. @@ -6885,6 +6904,10 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) sub->args[i].arg_type = ARG_PTR_TO_CTX; continue; } + if (btf_type_is_ptr(t) && btf_is_dynptr_ptr(btf, t)) { + sub->args[i].arg_type = ARG_PTR_TO_DYNPTR | MEM_RDONLY; + continue; + } if (is_global && btf_type_is_ptr(t)) { u32 mem_size; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 4caabfdc15aa..f13008d27f35 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9296,6 +9296,10 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog, bpf_log(log, "arg#%d is expected to be non-NULL\n", i); return -EINVAL; } + } else if (arg->arg_type == (ARG_PTR_TO_DYNPTR | MEM_RDONLY)) { + ret = process_dynptr_func(env, regno, -1, arg->arg_type, 0); + if (ret) + return ret; } else { bpf_log(log, "verifier bug: unrecognized arg#%d type %d\n", i, arg->arg_type); @@ -20052,6 +20056,9 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog) } else if (arg->arg_type == ARG_ANYTHING) { reg->type = SCALAR_VALUE; mark_reg_unknown(env, regs, i); + } else if (arg->arg_type == (ARG_PTR_TO_DYNPTR | MEM_RDONLY)) { + /* assume unspecial LOCAL dynptr type */ + __mark_dynptr_reg(reg, BPF_DYNPTR_TYPE_LOCAL, true, ++env->id_gen); } else if (base_type(arg->arg_type) == ARG_PTR_TO_MEM) { reg->type = PTR_TO_MEM; if (arg->arg_type & PTR_MAYBE_NULL) -- cgit v1.2.3 From 7ac5c53e00735d183a0f5e2cfce5eeb6c16319f2 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Sat, 16 Dec 2023 21:10:51 +0800 Subject: bpf: Use c->unit_size to select target cache during free MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit At present, bpf memory allocator uses check_obj_size() to ensure that ksize() of allocated pointer is equal with the unit_size of used bpf_mem_cache. Its purpose is to prevent bpf_mem_free() from selecting a bpf_mem_cache which has different unit_size compared with the bpf_mem_cache used for allocation. But as reported by lkp, the return value of ksize() or kmalloc_size_roundup() may change due to slab merge and it will lead to the warning report in check_obj_size(). The reported warning happened as follows: (1) in bpf_mem_cache_adjust_size(), kmalloc_size_roundup(96) returns the object_size of kmalloc-96 instead of kmalloc-cg-96. The object_size of kmalloc-96 is 96, so size_index for 96 is not adjusted accordingly. (2) the object_size of kmalloc-cg-96 is adjust from 96 to 128 due to slab merge in __kmem_cache_alias(). For SLAB, SLAB_HWCACHE_ALIGN is enabled by default for kmalloc slab, so align is 64 and size is 128 for kmalloc-cg-96. SLUB has a similar merge logic, but its object_size will not be changed, because its align is 8 under x86-64. (3) when unit_alloc() does kmalloc_node(96, __GFP_ACCOUNT, node), ksize() returns 128 instead of 96 for the returned pointer. (4) the warning in check_obj_size() is triggered. Considering the slab merge can happen in anytime (e.g, a slab created in a new module), the following case is also possible: during the initialization of bpf_global_ma, there is no slab merge and ksize() for a 96-bytes object returns 96. But after that a new slab created by a kernel module is merged to kmalloc-cg-96 and the object_size of kmalloc-cg-96 is adjust from 96 to 128 (which is possible for x86-64 + CONFIG_SLAB, because its alignment requirement is 64 for 96-bytes slab). So soon or later, when bpf_global_ma frees a 96-byte-sized pointer which is allocated from bpf_mem_cache with unit_size=96, bpf_mem_free() will free the pointer through a bpf_mem_cache in which unit_size is 128, because the return value of ksize() changes. The warning for the mismatch will be triggered again. A feasible fix is introducing similar APIs compared with ksize() and kmalloc_size_roundup() to return the actually-allocated size instead of size which may change due to slab merge, but it will introduce unnecessary dependency on the implementation details of mm subsystem. As for now the pointer of bpf_mem_cache is saved in the 8-bytes area (or 4-bytes under 32-bit host) above the returned pointer, using unit_size in the saved bpf_mem_cache to select the target cache instead of inferring the size from the pointer itself. Beside no extra dependency on mm subsystem, the performance for bpf_mem_free_rcu() is also improved as shown below. Before applying the patch, the performances of bpf_mem_alloc() and bpf_mem_free_rcu() on 8-CPUs VM with one producer are as follows: kmalloc : alloc 11.69 ± 0.28M/s free 29.58 ± 0.93M/s percpu : alloc 14.11 ± 0.52M/s free 14.29 ± 0.99M/s After apply the patch, the performance for bpf_mem_free_rcu() increases 9% and 146% for kmalloc memory and per-cpu memory respectively: kmalloc: alloc 11.01 ± 0.03M/s free 32.42 ± 0.48M/s percpu: alloc 12.84 ± 0.12M/s free 35.24 ± 0.23M/s After the fixes, there is no need to adjust size_index to fix the mismatch between allocation and free, so remove it as well. Also return NULL instead of ZERO_SIZE_PTR for zero-sized alloc in bpf_mem_alloc(), because there is no bpf_mem_cache pointer saved above ZERO_SIZE_PTR. Fixes: 9077fc228f09 ("bpf: Use kmalloc_size_roundup() to adjust size_index") Reported-by: kernel test robot Closes: https://lore.kernel.org/bpf/202310302113.9f8fe705-oliver.sang@intel.com Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20231216131052.27621-2-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/memalloc.c | 105 ++++++-------------------------------------------- 1 file changed, 11 insertions(+), 94 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index 6a51cfe4c2d6..aa0fbf000a12 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -490,27 +490,6 @@ static void prefill_mem_cache(struct bpf_mem_cache *c, int cpu) alloc_bulk(c, c->unit_size <= 256 ? 4 : 1, cpu_to_node(cpu), false); } -static int check_obj_size(struct bpf_mem_cache *c, unsigned int idx) -{ - struct llist_node *first; - unsigned int obj_size; - - first = c->free_llist.first; - if (!first) - return 0; - - if (c->percpu_size) - obj_size = pcpu_alloc_size(((void **)first)[1]); - else - obj_size = ksize(first); - if (obj_size != c->unit_size) { - WARN_ONCE(1, "bpf_mem_cache[%u]: percpu %d, unexpected object size %u, expect %u\n", - idx, c->percpu_size, obj_size, c->unit_size); - return -EINVAL; - } - return 0; -} - /* When size != 0 bpf_mem_cache for each cpu. * This is typical bpf hash map use case when all elements have equal size. * @@ -521,10 +500,10 @@ static int check_obj_size(struct bpf_mem_cache *c, unsigned int idx) int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu) { static u16 sizes[NUM_CACHES] = {96, 192, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096}; - int cpu, i, err, unit_size, percpu_size = 0; struct bpf_mem_caches *cc, __percpu *pcc; struct bpf_mem_cache *c, __percpu *pc; struct obj_cgroup *objcg = NULL; + int cpu, i, unit_size, percpu_size = 0; /* room for llist_node and per-cpu pointer */ if (percpu) @@ -560,7 +539,6 @@ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu) pcc = __alloc_percpu_gfp(sizeof(*cc), 8, GFP_KERNEL); if (!pcc) return -ENOMEM; - err = 0; #ifdef CONFIG_MEMCG_KMEM objcg = get_obj_cgroup_from_current(); #endif @@ -574,28 +552,12 @@ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu) c->tgt = c; init_refill_work(c); - /* Another bpf_mem_cache will be used when allocating - * c->unit_size in bpf_mem_alloc(), so doesn't prefill - * for the bpf_mem_cache because these free objects will - * never be used. - */ - if (i != bpf_mem_cache_idx(c->unit_size)) - continue; prefill_mem_cache(c, cpu); - err = check_obj_size(c, i); - if (err) - goto out; } } -out: ma->caches = pcc; - /* refill_work is either zeroed or initialized, so it is safe to - * call irq_work_sync(). - */ - if (err) - bpf_mem_alloc_destroy(ma); - return err; + return 0; } static void drain_mem_cache(struct bpf_mem_cache *c) @@ -869,7 +831,7 @@ void notrace *bpf_mem_alloc(struct bpf_mem_alloc *ma, size_t size) void *ret; if (!size) - return ZERO_SIZE_PTR; + return NULL; idx = bpf_mem_cache_idx(size + LLIST_NODE_SZ); if (idx < 0) @@ -879,26 +841,17 @@ void notrace *bpf_mem_alloc(struct bpf_mem_alloc *ma, size_t size) return !ret ? NULL : ret + LLIST_NODE_SZ; } -static notrace int bpf_mem_free_idx(void *ptr, bool percpu) -{ - size_t size; - - if (percpu) - size = pcpu_alloc_size(*((void **)ptr)); - else - size = ksize(ptr - LLIST_NODE_SZ); - return bpf_mem_cache_idx(size); -} - void notrace bpf_mem_free(struct bpf_mem_alloc *ma, void *ptr) { + struct bpf_mem_cache *c; int idx; if (!ptr) return; - idx = bpf_mem_free_idx(ptr, ma->percpu); - if (idx < 0) + c = *(void **)(ptr - LLIST_NODE_SZ); + idx = bpf_mem_cache_idx(c->unit_size); + if (WARN_ON_ONCE(idx < 0)) return; unit_free(this_cpu_ptr(ma->caches)->cache + idx, ptr); @@ -906,13 +859,15 @@ void notrace bpf_mem_free(struct bpf_mem_alloc *ma, void *ptr) void notrace bpf_mem_free_rcu(struct bpf_mem_alloc *ma, void *ptr) { + struct bpf_mem_cache *c; int idx; if (!ptr) return; - idx = bpf_mem_free_idx(ptr, ma->percpu); - if (idx < 0) + c = *(void **)(ptr - LLIST_NODE_SZ); + idx = bpf_mem_cache_idx(c->unit_size); + if (WARN_ON_ONCE(idx < 0)) return; unit_free_rcu(this_cpu_ptr(ma->caches)->cache + idx, ptr); @@ -986,41 +941,3 @@ void notrace *bpf_mem_cache_alloc_flags(struct bpf_mem_alloc *ma, gfp_t flags) return !ret ? NULL : ret + LLIST_NODE_SZ; } - -/* The alignment of dynamic per-cpu area is 8, so c->unit_size and the - * actual size of dynamic per-cpu area will always be matched and there is - * no need to adjust size_index for per-cpu allocation. However for the - * simplicity of the implementation, use an unified size_index for both - * kmalloc and per-cpu allocation. - */ -static __init int bpf_mem_cache_adjust_size(void) -{ - unsigned int size; - - /* Adjusting the indexes in size_index() according to the object_size - * of underlying slab cache, so bpf_mem_alloc() will select a - * bpf_mem_cache with unit_size equal to the object_size of - * the underlying slab cache. - * - * The maximal value of KMALLOC_MIN_SIZE and __kmalloc_minalign() is - * 256-bytes, so only do adjustment for [8-bytes, 192-bytes]. - */ - for (size = 192; size >= 8; size -= 8) { - unsigned int kmalloc_size, index; - - kmalloc_size = kmalloc_size_roundup(size); - if (kmalloc_size == size) - continue; - - if (kmalloc_size <= 192) - index = size_index[(kmalloc_size - 1) / 8]; - else - index = fls(kmalloc_size - 1) - 1; - /* Only overwrite if necessary */ - if (size_index[(size - 1) / 8] != index) - size_index[(size - 1) / 8] = index; - } - - return 0; -} -subsys_initcall(bpf_mem_cache_adjust_size); -- cgit v1.2.3 From b08c8fc0411dce0fc44b78ce4d67f1b67c35c196 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Wed, 20 Dec 2023 14:38:05 +0100 Subject: bpf: Re-support uid and gid when mounting bpffs For a clean, conflict-free revert of the token-related patches in commit d17aff807f84 ("Revert BPF token-related functionality"), the bpf fs commit 750e785796bb ("bpf: Support uid and gid when mounting bpffs") was undone temporarily as well. This patch manually re-adds the functionality from the original one back in 750e785796bb, no other functional changes intended. Testing: # mount -t bpf -o uid=65534,gid=65534 bpffs ./foo # ls -la . | grep foo drwxrwxrwt 2 nobody nogroup 0 Dec 20 13:16 foo # mount -t bpf bpffs on /root/foo type bpf (rw,relatime,uid=65534,gid=65534) Also, passing invalid arguments for uid/gid are properly rejected as expected. Fixes: d17aff807f84 ("Revert BPF token-related functionality") Signed-off-by: Daniel Borkmann Reviewed-by: Christian Brauner Cc: Jie Jiang Cc: Andrii Nakryiko Cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/bpf/20231220133805.20953-1-daniel@iogearbox.net --- kernel/bpf/inode.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 51 insertions(+), 2 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c index 1aafb2ff2e95..41e0a55c35f5 100644 --- a/kernel/bpf/inode.c +++ b/kernel/bpf/inode.c @@ -599,8 +599,15 @@ EXPORT_SYMBOL(bpf_prog_get_type_path); */ static int bpf_show_options(struct seq_file *m, struct dentry *root) { - umode_t mode = d_inode(root)->i_mode & S_IALLUGO & ~S_ISVTX; - + struct inode *inode = d_inode(root); + umode_t mode = inode->i_mode & S_IALLUGO & ~S_ISVTX; + + if (!uid_eq(inode->i_uid, GLOBAL_ROOT_UID)) + seq_printf(m, ",uid=%u", + from_kuid_munged(&init_user_ns, inode->i_uid)); + if (!gid_eq(inode->i_gid, GLOBAL_ROOT_GID)) + seq_printf(m, ",gid=%u", + from_kgid_munged(&init_user_ns, inode->i_gid)); if (mode != S_IRWXUGO) seq_printf(m, ",mode=%o", mode); return 0; @@ -625,15 +632,21 @@ static const struct super_operations bpf_super_ops = { }; enum { + OPT_UID, + OPT_GID, OPT_MODE, }; static const struct fs_parameter_spec bpf_fs_parameters[] = { + fsparam_u32 ("uid", OPT_UID), + fsparam_u32 ("gid", OPT_GID), fsparam_u32oct ("mode", OPT_MODE), {} }; struct bpf_mount_opts { + kuid_t uid; + kgid_t gid; umode_t mode; }; @@ -641,6 +654,8 @@ static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param) { struct bpf_mount_opts *opts = fc->fs_private; struct fs_parse_result result; + kuid_t uid; + kgid_t gid; int opt; opt = fs_parse(fc, bpf_fs_parameters, param, &result); @@ -662,12 +677,42 @@ static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param) } switch (opt) { + case OPT_UID: + uid = make_kuid(current_user_ns(), result.uint_32); + if (!uid_valid(uid)) + goto bad_value; + + /* + * The requested uid must be representable in the + * filesystem's idmapping. + */ + if (!kuid_has_mapping(fc->user_ns, uid)) + goto bad_value; + + opts->uid = uid; + break; + case OPT_GID: + gid = make_kgid(current_user_ns(), result.uint_32); + if (!gid_valid(gid)) + goto bad_value; + + /* + * The requested gid must be representable in the + * filesystem's idmapping. + */ + if (!kgid_has_mapping(fc->user_ns, gid)) + goto bad_value; + + opts->gid = gid; + break; case OPT_MODE: opts->mode = result.uint_32 & S_IALLUGO; break; } return 0; +bad_value: + return invalfc(fc, "Bad value for '%s'", param->key); } struct bpf_preload_ops *bpf_preload_ops; @@ -750,6 +795,8 @@ static int bpf_fill_super(struct super_block *sb, struct fs_context *fc) sb->s_op = &bpf_super_ops; inode = sb->s_root->d_inode; + inode->i_uid = opts->uid; + inode->i_gid = opts->gid; inode->i_op = &bpf_dir_iops; inode->i_mode &= ~S_IALLUGO; populate_bpffs(sb->s_root); @@ -785,6 +832,8 @@ static int bpf_init_fs_context(struct fs_context *fc) return -ENOMEM; opts->mode = S_IRWXUGO; + opts->uid = current_fsuid(); + opts->gid = current_fsgid(); fc->fs_private = opts; fc->ops = &bpf_context_ops; -- cgit v1.2.3 From 5abde62465222edd3080b70099bd809f166d5d7d Mon Sep 17 00:00:00 2001 From: Simon Horman Date: Thu, 21 Dec 2023 18:03:52 +0100 Subject: bpf: Avoid unnecessary use of comma operator in verifier Although it does not seem to have any untoward side-effects, the use of ';' to separate to assignments seems more appropriate than ','. Flagged by clang-17 -Wcomma No functional change intended. Compile tested only. Signed-off-by: Simon Horman Signed-off-by: Daniel Borkmann Reviewed-by: Dave Marchevsky Link: https://lore.kernel.org/bpf/20231221-bpf-verifier-comma-v1-1-cde2530912e9@kernel.org --- kernel/bpf/verifier.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f13008d27f35..a376eb609c41 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9616,7 +9616,7 @@ static int set_find_vma_callback_state(struct bpf_verifier_env *env, callee->regs[BPF_REG_2].type = PTR_TO_BTF_ID; __mark_reg_known_zero(&callee->regs[BPF_REG_2]); callee->regs[BPF_REG_2].btf = btf_vmlinux; - callee->regs[BPF_REG_2].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_VMA], + callee->regs[BPF_REG_2].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_VMA]; /* pointer to stack or null */ callee->regs[BPF_REG_3] = caller->regs[BPF_REG_4]; -- cgit v1.2.3 From 1e2f2d31997a9496f99e2b43255d6a48b06fbcc2 Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Fri, 15 Dec 2023 15:51:54 -0500 Subject: Kill sched.h dependency on rcupdate.h by moving cond_resched_rcu() to rcupdate_wait.h, we can kill another big sched.h dependency. Signed-off-by: Kent Overstreet --- arch/powerpc/kvm/book3s_64_vio.c | 1 + include/linux/rcupdate_wait.h | 10 ++++++++++ include/linux/sched.h | 15 +++++---------- include/linux/sched/task.h | 1 + kernel/bpf/hashtab.c | 1 + lib/test_rhashtable.c | 1 + mm/filemap.c | 1 + mm/khugepaged.c | 1 + mm/shmem.c | 1 + net/ipv4/fib_trie.c | 1 + net/netfilter/ipset/ip_set_bitmap_gen.h | 2 ++ net/netfilter/ipset/ip_set_hash_gen.h | 1 + net/netfilter/ipvs/ip_vs_conn.c | 1 + net/netfilter/ipvs/ip_vs_est.c | 1 + 14 files changed, 28 insertions(+), 10 deletions(-) (limited to 'kernel/bpf') diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c index 14c6d7e318da..b569ebaa590e 100644 --- a/arch/powerpc/kvm/book3s_64_vio.c +++ b/arch/powerpc/kvm/book3s_64_vio.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include diff --git a/include/linux/rcupdate_wait.h b/include/linux/rcupdate_wait.h index 5e0f74f2f8ca..d07f0848802e 100644 --- a/include/linux/rcupdate_wait.h +++ b/include/linux/rcupdate_wait.h @@ -8,6 +8,7 @@ #include #include +#include /* * Structure allowing asynchronous waiting on RCU. @@ -55,4 +56,13 @@ do { \ #define synchronize_rcu_mult(...) \ _wait_rcu_gp(IS_ENABLED(CONFIG_TINY_RCU), __VA_ARGS__) +static inline void cond_resched_rcu(void) +{ +#if defined(CONFIG_DEBUG_ATOMIC_SLEEP) || !defined(CONFIG_PREEMPT_RCU) + rcu_read_unlock(); + cond_resched(); + rcu_read_lock(); +#endif +} + #endif /* _LINUX_SCHED_RCUPDATE_WAIT_H */ diff --git a/include/linux/sched.h b/include/linux/sched.h index a588b94988bc..814bfdafbc1c 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -10,9 +10,14 @@ #include #include +#include +#include +#include +#include #include #include +#include #include #include #include @@ -23,7 +28,6 @@ #include #include #include -#include #include #include #include @@ -2059,15 +2063,6 @@ extern int __cond_resched_rwlock_write(rwlock_t *lock); __cond_resched_rwlock_write(lock); \ }) -static inline void cond_resched_rcu(void) -{ -#if defined(CONFIG_DEBUG_ATOMIC_SLEEP) || !defined(CONFIG_PREEMPT_RCU) - rcu_read_unlock(); - cond_resched(); - rcu_read_lock(); -#endif -} - #ifdef CONFIG_PREEMPT_DYNAMIC extern bool preempt_model_none(void); diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h index 1880ae21a9cb..538cdfbe895f 100644 --- a/include/linux/sched/task.h +++ b/include/linux/sched/task.h @@ -7,6 +7,7 @@ * functionality: */ +#include #include #include #include diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index fd8d4b0addfc..3ba98ed2b3f9 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -7,6 +7,7 @@ #include #include #include +#include #include #include #include diff --git a/lib/test_rhashtable.c b/lib/test_rhashtable.c index c20f6cb4bf55..42b585208249 100644 --- a/lib/test_rhashtable.c +++ b/lib/test_rhashtable.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include #include diff --git a/mm/filemap.c b/mm/filemap.c index f1c8c278310f..1219ffc04a26 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -45,6 +45,7 @@ #include #include #include +#include #include #include #include "internal.h" diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 064654717843..47a20a4ece09 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include #include diff --git a/mm/shmem.c b/mm/shmem.c index 91e2620148b2..98f6ca7bdae1 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -79,6 +79,7 @@ static struct vfsmount *shm_mnt __ro_after_init; #include #include #include +#include #include diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index 9bdfdab906fe..3ff35f811765 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -52,6 +52,7 @@ #include #include #include +#include #include #include #include diff --git a/net/netfilter/ipset/ip_set_bitmap_gen.h b/net/netfilter/ipset/ip_set_bitmap_gen.h index 26ab0e9612d8..21f7860e8fa1 100644 --- a/net/netfilter/ipset/ip_set_bitmap_gen.h +++ b/net/netfilter/ipset/ip_set_bitmap_gen.h @@ -4,6 +4,8 @@ #ifndef __IP_SET_BITMAP_IP_GEN_H #define __IP_SET_BITMAP_IP_GEN_H +#include + #define mtype_do_test IPSET_TOKEN(MTYPE, _do_test) #define mtype_gc_test IPSET_TOKEN(MTYPE, _gc_test) #define mtype_is_filled IPSET_TOKEN(MTYPE, _is_filled) diff --git a/net/netfilter/ipset/ip_set_hash_gen.h b/net/netfilter/ipset/ip_set_hash_gen.h index 7c2399541771..cbf80da9a01c 100644 --- a/net/netfilter/ipset/ip_set_hash_gen.h +++ b/net/netfilter/ipset/ip_set_hash_gen.h @@ -5,6 +5,7 @@ #define _IP_SET_HASH_GEN_H #include +#include #include #include #include diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c index 9065da3cdd12..a743db073887 100644 --- a/net/netfilter/ipvs/ip_vs_conn.c +++ b/net/netfilter/ipvs/ip_vs_conn.c @@ -31,6 +31,7 @@ #include #include #include +#include #include #include diff --git a/net/netfilter/ipvs/ip_vs_est.c b/net/netfilter/ipvs/ip_vs_est.c index c5970ba416ae..f821ad2e19b3 100644 --- a/net/netfilter/ipvs/ip_vs_est.c +++ b/net/netfilter/ipvs/ip_vs_est.c @@ -21,6 +21,7 @@ #include #include #include +#include #include -- cgit v1.2.3 From 8a021e7fa10576eeb3938328f39bbf98fe7d4715 Mon Sep 17 00:00:00 2001 From: Andrei Matei Date: Thu, 21 Dec 2023 18:22:24 -0500 Subject: bpf: Simplify checking size of helper accesses This patch simplifies the verification of size arguments associated to pointer arguments to helpers and kfuncs. Many helpers take a pointer argument followed by the size of the memory access performed to be performed through that pointer. Before this patch, the handling of the size argument in check_mem_size_reg() was confusing and wasteful: if the size register's lower bound was 0, then the verification was done twice: once considering the size of the access to be the lower-bound of the respective argument, and once considering the upper bound (even if the two are the same). The upper bound checking is a super-set of the lower-bound checking(*), except: the only point of the lower-bound check is to handle the case where zero-sized-accesses are explicitly not allowed and the lower-bound is zero. This static condition is now checked explicitly, replacing a much more complex, expensive and confusing verification call to check_helper_mem_access(). Error messages change in this patch. Before, messages about illegal zero-size accesses depended on the type of the pointer and on other conditions, and sometimes the message was plain wrong: in some tests that changed you'll see that the old message was something like "R1 min value is outside of the allowed memory range", where R1 is the pointer register; the error was wrongly claiming that the pointer was bad instead of the size being bad. Other times the information that the size came for a register with a possible range of values was wrong, and the error presented the size as a fixed zero. Now the errors refer to the right register. However, the old error messages did contain useful information about the pointer register which is now lost; recovering this information was deemed not important enough. (*) Besides standing to reason that the checks for a bigger size access are a super-set of the checks for a smaller size access, I have also mechanically verified this by reading the code for all types of pointers. I could convince myself that it's true for all but PTR_TO_BTF_ID (check_ptr_to_btf_access). There, simply looking line-by-line does not immediately prove what we want. If anyone has any qualms, let me know. Signed-off-by: Andrei Matei Signed-off-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20231221232225.568730-2-andreimatei1@gmail.com --- kernel/bpf/verifier.c | 10 ++++------ .../testing/selftests/bpf/progs/verifier_helper_value_access.c | 8 ++++---- tools/testing/selftests/bpf/progs/verifier_raw_stack.c | 2 +- 3 files changed, 9 insertions(+), 11 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index a376eb609c41..d4e31f61de0e 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7279,12 +7279,10 @@ static int check_mem_size_reg(struct bpf_verifier_env *env, return -EACCES; } - if (reg->umin_value == 0) { - err = check_helper_mem_access(env, regno - 1, 0, - zero_size_allowed, - meta); - if (err) - return err; + if (reg->umin_value == 0 && !zero_size_allowed) { + verbose(env, "R%d invalid zero-sized read: u64=[%lld,%lld]\n", + regno, reg->umin_value, reg->umax_value); + return -EACCES; } if (reg->umax_value >= BPF_MAX_VAR_SIZ) { diff --git a/tools/testing/selftests/bpf/progs/verifier_helper_value_access.c b/tools/testing/selftests/bpf/progs/verifier_helper_value_access.c index 692216c0ad3d..3e8340c2408f 100644 --- a/tools/testing/selftests/bpf/progs/verifier_helper_value_access.c +++ b/tools/testing/selftests/bpf/progs/verifier_helper_value_access.c @@ -91,7 +91,7 @@ l0_%=: exit; \ SEC("tracepoint") __description("helper access to map: empty range") -__failure __msg("invalid access to map value, value_size=48 off=0 size=0") +__failure __msg("R2 invalid zero-sized read") __naked void access_to_map_empty_range(void) { asm volatile (" \ @@ -221,7 +221,7 @@ l0_%=: exit; \ SEC("tracepoint") __description("helper access to adjusted map (via const imm): empty range") -__failure __msg("invalid access to map value, value_size=48 off=4 size=0") +__failure __msg("R2 invalid zero-sized read") __naked void via_const_imm_empty_range(void) { asm volatile (" \ @@ -386,7 +386,7 @@ l0_%=: exit; \ SEC("tracepoint") __description("helper access to adjusted map (via const reg): empty range") -__failure __msg("R1 min value is outside of the allowed memory range") +__failure __msg("R2 invalid zero-sized read") __naked void via_const_reg_empty_range(void) { asm volatile (" \ @@ -556,7 +556,7 @@ l0_%=: exit; \ SEC("tracepoint") __description("helper access to adjusted map (via variable): empty range") -__failure __msg("R1 min value is outside of the allowed memory range") +__failure __msg("R2 invalid zero-sized read") __naked void map_via_variable_empty_range(void) { asm volatile (" \ diff --git a/tools/testing/selftests/bpf/progs/verifier_raw_stack.c b/tools/testing/selftests/bpf/progs/verifier_raw_stack.c index f67390224a9c..7cc83acac727 100644 --- a/tools/testing/selftests/bpf/progs/verifier_raw_stack.c +++ b/tools/testing/selftests/bpf/progs/verifier_raw_stack.c @@ -64,7 +64,7 @@ __naked void load_bytes_negative_len_2(void) SEC("tc") __description("raw_stack: skb_load_bytes, zero len") -__failure __msg("invalid zero-sized read") +__failure __msg("R4 invalid zero-sized read: u64=[0,0]") __naked void skb_load_bytes_zero_len(void) { asm volatile (" \ -- cgit v1.2.3 From 9beda16c257d55213f70adee2f16d7f13a8502e1 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Thu, 21 Dec 2023 19:17:34 -0800 Subject: bpf: Avoid unnecessary extra percpu memory allocation Currently, for percpu memory allocation, say if the user requests allocation size to be 32 bytes, the actually calculated size will be 40 bytes and it further rounds to 64 bytes, and eventually 64 bytes are allocated, wasting 32-byte memory. Change bpf_mem_alloc() to calculate the cache index based on the user-provided allocation size so unnecessary extra memory can be avoided. Suggested-by: Hou Tao Acked-by: Hou Tao Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20231222031734.1288400-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov --- kernel/bpf/memalloc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index aa0fbf000a12..288ec4a967d0 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -833,7 +833,9 @@ void notrace *bpf_mem_alloc(struct bpf_mem_alloc *ma, size_t size) if (!size) return NULL; - idx = bpf_mem_cache_idx(size + LLIST_NODE_SZ); + if (!ma->percpu) + size += LLIST_NODE_SZ; + idx = bpf_mem_cache_idx(size); if (idx < 0) return NULL; -- cgit v1.2.3 From 9fc8e802048ad150e8032c4f3dbf40112160cfe9 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Thu, 21 Dec 2023 19:17:39 -0800 Subject: bpf: Add objcg to bpf_mem_alloc The objcg is a bpf_mem_alloc level property since all bpf_mem_cache's are with the same objcg. This patch made such a property explicit. The next patch will use this property to save and restore objcg for percpu unit allocator. Acked-by: Hou Tao Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20231222031739.1288590-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov --- include/linux/bpf_mem_alloc.h | 1 + kernel/bpf/memalloc.c | 11 ++++++----- 2 files changed, 7 insertions(+), 5 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf_mem_alloc.h b/include/linux/bpf_mem_alloc.h index bb1223b21308..acef8c808599 100644 --- a/include/linux/bpf_mem_alloc.h +++ b/include/linux/bpf_mem_alloc.h @@ -11,6 +11,7 @@ struct bpf_mem_caches; struct bpf_mem_alloc { struct bpf_mem_caches __percpu *caches; struct bpf_mem_cache __percpu *cache; + struct obj_cgroup *objcg; bool percpu; struct work_struct work; }; diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index 288ec4a967d0..4a21050f0359 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -523,6 +523,7 @@ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu) if (memcg_bpf_enabled()) objcg = get_obj_cgroup_from_current(); #endif + ma->objcg = objcg; for_each_possible_cpu(cpu) { c = per_cpu_ptr(pc, cpu); c->unit_size = unit_size; @@ -542,6 +543,7 @@ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu) #ifdef CONFIG_MEMCG_KMEM objcg = get_obj_cgroup_from_current(); #endif + ma->objcg = objcg; for_each_possible_cpu(cpu) { cc = per_cpu_ptr(pcc, cpu); for (i = 0; i < NUM_CACHES; i++) { @@ -691,9 +693,8 @@ void bpf_mem_alloc_destroy(struct bpf_mem_alloc *ma) rcu_in_progress += atomic_read(&c->call_rcu_ttrace_in_progress); rcu_in_progress += atomic_read(&c->call_rcu_in_progress); } - /* objcg is the same across cpus */ - if (c->objcg) - obj_cgroup_put(c->objcg); + if (ma->objcg) + obj_cgroup_put(ma->objcg); destroy_mem_alloc(ma, rcu_in_progress); } if (ma->caches) { @@ -709,8 +710,8 @@ void bpf_mem_alloc_destroy(struct bpf_mem_alloc *ma) rcu_in_progress += atomic_read(&c->call_rcu_in_progress); } } - if (c->objcg) - obj_cgroup_put(c->objcg); + if (ma->objcg) + obj_cgroup_put(ma->objcg); destroy_mem_alloc(ma, rcu_in_progress); } } -- cgit v1.2.3 From c39aa3b289e9c10d0d246cd919b06809f13b72b8 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Thu, 21 Dec 2023 19:17:45 -0800 Subject: bpf: Allow per unit prefill for non-fix-size percpu memory allocator Commit 41a5db8d8161 ("Add support for non-fix-size percpu mem allocation") added support for non-fix-size percpu memory allocation. Such allocation will allocate percpu memory for all buckets on all cpus and the memory consumption is in the order to quadratic. For example, let us say, 4 cpus, unit size 16 bytes, so each cpu has 16 * 4 = 64 bytes, with 4 cpus, total will be 64 * 4 = 256 bytes. Then let us say, 8 cpus with the same unit size, each cpu has 16 * 8 = 128 bytes, with 8 cpus, total will be 128 * 8 = 1024 bytes. So if the number of cpus doubles, the number of memory consumption will be 4 times. So for a system with large number of cpus, the memory consumption goes up quickly with quadratic order. For example, for 4KB percpu allocation, 128 cpus. The total memory consumption will 4KB * 128 * 128 = 64MB. Things will become worse if the number of cpus is bigger (e.g., 512, 1024, etc.) In Commit 41a5db8d8161, the non-fix-size percpu memory allocation is done in boot time, so for system with large number of cpus, the initial percpu memory consumption is very visible. For example, for 128 cpu system, the total percpu memory allocation will be at least (16 + 32 + 64 + 96 + 128 + 196 + 256 + 512 + 1024 + 2048 + 4096) * 128 * 128 = ~138MB. which is pretty big. It will be even bigger for larger number of cpus. Note that the current prefill also allocates 4 entries if the unit size is less than 256. So on top of 138MB memory consumption, this will add more consumption with 3 * (16 + 32 + 64 + 96 + 128 + 196 + 256) * 128 * 128 = ~38MB. Next patch will try to reduce this memory consumption. Later on, Commit 1fda5bb66ad8 ("bpf: Do not allocate percpu memory at init stage") moved the non-fix-size percpu memory allocation to bpf verificaiton stage. Once a particular bpf_percpu_obj_new() is called by bpf program, the memory allocator will try to fill in the cache with all sizes, causing the same amount of percpu memory consumption as in the boot stage. To reduce the initial percpu memory consumption for non-fix-size percpu memory allocation, instead of filling the cache with all supported allocation sizes, this patch intends to fill the cache only for the requested size. As typically users will not use large percpu data structure, this can save memory significantly. For example, the allocation size is 64 bytes with 128 cpus. Then total percpu memory amount will be 64 * 128 * 128 = 1MB, much less than previous 138MB. Signed-off-by: Yonghong Song Acked-by: Hou Tao Link: https://lore.kernel.org/r/20231222031745.1289082-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov --- include/linux/bpf_mem_alloc.h | 7 ++++++ kernel/bpf/memalloc.c | 57 ++++++++++++++++++++++++++++++++++++++++++- kernel/bpf/verifier.c | 37 +++++++++++++++++----------- 3 files changed, 86 insertions(+), 15 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf_mem_alloc.h b/include/linux/bpf_mem_alloc.h index acef8c808599..aaf004d94322 100644 --- a/include/linux/bpf_mem_alloc.h +++ b/include/linux/bpf_mem_alloc.h @@ -22,8 +22,15 @@ struct bpf_mem_alloc { * 'size = 0' is for bpf_mem_alloc which manages many fixed-size objects. * Alloc and free are done with bpf_mem_{alloc,free}() and the size of * the returned object is given by the size argument of bpf_mem_alloc(). + * If percpu equals true, error will be returned in order to avoid + * large memory consumption and the below bpf_mem_alloc_percpu_unit_init() + * should be used to do on-demand per-cpu allocation for each size. */ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu); +/* Initialize a non-fix-size percpu memory allocator */ +int bpf_mem_alloc_percpu_init(struct bpf_mem_alloc *ma, struct obj_cgroup *objcg); +/* The percpu allocation with a specific unit size. */ +int bpf_mem_alloc_percpu_unit_init(struct bpf_mem_alloc *ma, int size); void bpf_mem_alloc_destroy(struct bpf_mem_alloc *ma); /* kmalloc/kfree equivalent: */ diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index 4a21050f0359..f71da07eb8a0 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -121,6 +121,8 @@ struct bpf_mem_caches { struct bpf_mem_cache cache[NUM_CACHES]; }; +static const u16 sizes[NUM_CACHES] = {96, 192, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096}; + static struct llist_node notrace *__llist_del_first(struct llist_head *head) { struct llist_node *entry, *next; @@ -499,12 +501,14 @@ static void prefill_mem_cache(struct bpf_mem_cache *c, int cpu) */ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu) { - static u16 sizes[NUM_CACHES] = {96, 192, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096}; struct bpf_mem_caches *cc, __percpu *pcc; struct bpf_mem_cache *c, __percpu *pc; struct obj_cgroup *objcg = NULL; int cpu, i, unit_size, percpu_size = 0; + if (percpu && size == 0) + return -EINVAL; + /* room for llist_node and per-cpu pointer */ if (percpu) percpu_size = LLIST_NODE_SZ + sizeof(void *); @@ -524,6 +528,7 @@ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu) objcg = get_obj_cgroup_from_current(); #endif ma->objcg = objcg; + for_each_possible_cpu(cpu) { c = per_cpu_ptr(pc, cpu); c->unit_size = unit_size; @@ -562,6 +567,56 @@ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu) return 0; } +int bpf_mem_alloc_percpu_init(struct bpf_mem_alloc *ma, struct obj_cgroup *objcg) +{ + struct bpf_mem_caches __percpu *pcc; + + pcc = __alloc_percpu_gfp(sizeof(struct bpf_mem_caches), 8, GFP_KERNEL); + if (!pcc) + return -ENOMEM; + + ma->caches = pcc; + ma->objcg = objcg; + ma->percpu = true; + return 0; +} + +int bpf_mem_alloc_percpu_unit_init(struct bpf_mem_alloc *ma, int size) +{ + struct bpf_mem_caches *cc, __percpu *pcc; + int cpu, i, unit_size, percpu_size; + struct obj_cgroup *objcg; + struct bpf_mem_cache *c; + + i = bpf_mem_cache_idx(size); + if (i < 0) + return -EINVAL; + + /* room for llist_node and per-cpu pointer */ + percpu_size = LLIST_NODE_SZ + sizeof(void *); + + unit_size = sizes[i]; + objcg = ma->objcg; + pcc = ma->caches; + + for_each_possible_cpu(cpu) { + cc = per_cpu_ptr(pcc, cpu); + c = &cc->cache[i]; + if (cpu == 0 && c->unit_size) + break; + + c->unit_size = unit_size; + c->objcg = objcg; + c->percpu_size = percpu_size; + c->tgt = c; + + init_refill_work(c); + prefill_mem_cache(c, cpu); + } + + return 0; +} + static void drain_mem_cache(struct bpf_mem_cache *c) { bool percpu = !!c->percpu_size; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index d4e31f61de0e..e9699a2cfe4f 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -12139,20 +12139,6 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, if (meta.func_id == special_kfunc_list[KF_bpf_obj_new_impl] && !bpf_global_ma_set) return -ENOMEM; - if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) { - if (!bpf_global_percpu_ma_set) { - mutex_lock(&bpf_percpu_ma_lock); - if (!bpf_global_percpu_ma_set) { - err = bpf_mem_alloc_init(&bpf_global_percpu_ma, 0, true); - if (!err) - bpf_global_percpu_ma_set = true; - } - mutex_unlock(&bpf_percpu_ma_lock); - if (err) - return err; - } - } - if (((u64)(u32)meta.arg_constant.value) != meta.arg_constant.value) { verbose(env, "local type ID argument must be in range [0, U32_MAX]\n"); return -EINVAL; @@ -12173,6 +12159,29 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, return -EINVAL; } + if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) { + if (!bpf_global_percpu_ma_set) { + mutex_lock(&bpf_percpu_ma_lock); + if (!bpf_global_percpu_ma_set) { + /* Charge memory allocated with bpf_global_percpu_ma to + * root memcg. The obj_cgroup for root memcg is NULL. + */ + err = bpf_mem_alloc_percpu_init(&bpf_global_percpu_ma, NULL); + if (!err) + bpf_global_percpu_ma_set = true; + } + mutex_unlock(&bpf_percpu_ma_lock); + if (err) + return err; + } + + mutex_lock(&bpf_percpu_ma_lock); + err = bpf_mem_alloc_percpu_unit_init(&bpf_global_percpu_ma, ret_t->size); + mutex_unlock(&bpf_percpu_ma_lock); + if (err) + return err; + } + struct_meta = btf_find_struct_meta(ret_btf, ret_btf_id); if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) { if (!__btf_type_is_scalar_struct(env, ret_btf, ret_t, 0)) { -- cgit v1.2.3 From 5b95e638f134e552b5ba2976326c02babe248615 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Thu, 21 Dec 2023 19:17:50 -0800 Subject: bpf: Refill only one percpu element in memalloc Typically for percpu map element or data structure, once allocated, most operations are lookup or in-place update. Deletion are really rare. Currently, for percpu data strcture, 4 elements will be refilled if the size is <= 256. Let us just do with one element for percpu data. For example, for size 256 and 128 cpus, the potential saving will be 3 * 256 * 128 * 128 = 12MB. Acked-by: Hou Tao Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20231222031750.1289290-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov --- kernel/bpf/memalloc.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index f71da07eb8a0..a8ee6fb8401c 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -485,11 +485,16 @@ static void init_refill_work(struct bpf_mem_cache *c) static void prefill_mem_cache(struct bpf_mem_cache *c, int cpu) { - /* To avoid consuming memory assume that 1st run of bpf - * prog won't be doing more than 4 map_update_elem from - * irq disabled region + int cnt = 1; + + /* To avoid consuming memory, for non-percpu allocation, assume that + * 1st run of bpf prog won't be doing more than 4 map_update_elem from + * irq disabled region if unit size is less than or equal to 256. + * For all other cases, let us just do one allocation. */ - alloc_bulk(c, c->unit_size <= 256 ? 4 : 1, cpu_to_node(cpu), false); + if (!c->percpu_size && c->unit_size <= 256) + cnt = 4; + alloc_bulk(c, cnt, cpu_to_node(cpu), false); } /* When size != 0 bpf_mem_cache for each cpu. -- cgit v1.2.3 From 0e2ba9f96f9b82893ba19170ae48d46003f8ef44 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Thu, 21 Dec 2023 19:17:55 -0800 Subject: bpf: Use smaller low/high marks for percpu allocation Currently, refill low/high marks are set with the assumption of normal non-percpu memory allocation. For example, for an allocation size 256, for non-percpu memory allocation, low mark is 32 and high mark is 96, resulting in the batch allocation of 48 elements and the allocated memory will be 48 * 256 = 12KB for this particular cpu. Assuming an 128-cpu system, the total memory consumption across all cpus will be 12K * 128 = 1.5MB memory. This might be okay for non-percpu allocation, but may not be good for percpu allocation, which will consume 1.5MB * 128 = 192MB memory in the worst case if every cpu has a chance of memory allocation. In practice, percpu allocation is very rare compared to non-percpu allocation. So let us have smaller low/high marks which can avoid unnecessary memory consumption. Signed-off-by: Yonghong Song Acked-by: Hou Tao Link: https://lore.kernel.org/r/20231222031755.1289671-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov --- kernel/bpf/memalloc.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index a8ee6fb8401c..460c8f38fed6 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -464,11 +464,17 @@ static void notrace irq_work_raise(struct bpf_mem_cache *c) * consume ~ 11 Kbyte per cpu. * Typical case will be between 11K and 116K closer to 11K. * bpf progs can and should share bpf_mem_cache when possible. + * + * Percpu allocation is typically rare. To avoid potential unnecessary large + * memory consumption, set low_mark = 1 and high_mark = 3, resulting in c->batch = 1. */ static void init_refill_work(struct bpf_mem_cache *c) { init_irq_work(&c->refill_work, bpf_mem_refill); - if (c->unit_size <= 256) { + if (c->percpu_size) { + c->low_watermark = 1; + c->high_watermark = 3; + } else if (c->unit_size <= 256) { c->low_watermark = 32; c->high_watermark = 96; } else { -- cgit v1.2.3 From 5c1a37653260ed5d9c8b26fb7fe7b99629612982 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Thu, 21 Dec 2023 19:18:01 -0800 Subject: bpf: Limit up to 512 bytes for bpf_global_percpu_ma allocation For percpu data structure allocation with bpf_global_percpu_ma, the maximum data size is 4K. But for a system with large number of cpus, bigger data size (e.g., 2K, 4K) might consume a lot of memory. For example, the percpu memory consumption with unit size 2K and 1024 cpus will be 2K * 1K * 1k = 2GB memory. We should discourage such usage. Let us limit the maximum data size to be 512 for bpf_global_percpu_ma allocation. Acked-by: Hou Tao Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20231222031801.1290841-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index e9699a2cfe4f..d5f4ff1eb235 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -195,6 +195,8 @@ struct bpf_verifier_stack_elem { POISON_POINTER_DELTA)) #define BPF_MAP_PTR(X) ((struct bpf_map *)((X) & ~BPF_MAP_PTR_UNPRIV)) +#define BPF_GLOBAL_PERCPU_MA_MAX_SIZE 512 + static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx); static int release_reference(struct bpf_verifier_env *env, int ref_obj_id); static void invalidate_non_owning_refs(struct bpf_verifier_env *env); @@ -12160,6 +12162,12 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, } if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) { + if (ret_t->size > BPF_GLOBAL_PERCPU_MA_MAX_SIZE) { + verbose(env, "bpf_percpu_obj_new type size (%d) is greater than %d\n", + ret_t->size, BPF_GLOBAL_PERCPU_MA_MAX_SIZE); + return -EINVAL; + } + if (!bpf_global_percpu_ma_set) { mutex_lock(&bpf_percpu_ma_lock); if (!bpf_global_percpu_ma_set) { -- cgit v1.2.3 From 9ddf872b47e3ac8f27dbfc4a4737a976c7588de6 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Thu, 4 Jan 2024 08:57:44 -0800 Subject: bpf: Remove unnecessary cpu == 0 check in memalloc After merging the patch set [1] to reduce memory usage for bpf_global_percpu_ma, Alexei found a redundant check (cpu == 0) in function bpf_mem_alloc_percpu_unit_init() ([2]). Indeed, the check is unnecessary since c->unit_size will be all NULL or all non-NULL for all cpus before for_each_possible_cpu() loop. Removing the check makes code less confusing. [1] https://lore.kernel.org/all/20231222031729.1287957-1-yonghong.song@linux.dev/ [2] https://lore.kernel.org/all/20231222031745.1289082-1-yonghong.song@linux.dev/ Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20240104165744.702239-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov --- kernel/bpf/memalloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index 460c8f38fed6..550f02e2cb13 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -613,7 +613,7 @@ int bpf_mem_alloc_percpu_unit_init(struct bpf_mem_alloc *ma, int size) for_each_possible_cpu(cpu) { cc = per_cpu_ptr(pcc, cpu); c = &cc->cache[i]; - if (cpu == 0 && c->unit_size) + if (c->unit_size) break; c->unit_size = unit_size; -- cgit v1.2.3 From 19bfcdf9498aa968ea293417fbbc39e523527ca8 Mon Sep 17 00:00:00 2001 From: Dmitrii Dolgov <9erthalion6@gmail.com> Date: Wed, 3 Jan 2024 20:05:44 +0100 Subject: bpf: Relax tracing prog recursive attach rules Currently, it's not allowed to attach an fentry/fexit prog to another one fentry/fexit. At the same time it's not uncommon to see a tracing program with lots of logic in use, and the attachment limitation prevents usage of fentry/fexit for performance analysis (e.g. with "bpftool prog profile" command) in this case. An example could be falcosecurity libs project that uses tp_btf tracing programs. Following the corresponding discussion [1], the reason for that is to avoid tracing progs call cycles without introducing more complex solutions. But currently it seems impossible to load and attach tracing programs in a way that will form such a cycle. The limitation is coming from the fact that attach_prog_fd is specified at the prog load (thus making it impossible to attach to a program loaded after it in this way), as well as tracing progs not implementing link_detach. Replace "no same type" requirement with verification that no more than one level of attachment nesting is allowed. In this way only one fentry/fexit program could be attached to another fentry/fexit to cover profiling use case, and still no cycle could be formed. To implement, add a new field into bpf_prog_aux to track nested attachment for tracing programs. [1]: https://lore.kernel.org/bpf/20191108064039.2041889-16-ast@kernel.org/ Acked-by: Jiri Olsa Acked-by: Song Liu Signed-off-by: Dmitrii Dolgov <9erthalion6@gmail.com> Link: https://lore.kernel.org/r/20240103190559.14750-2-9erthalion6@gmail.com Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 1 + kernel/bpf/syscall.c | 23 ++++++++++++++++++++++- kernel/bpf/verifier.c | 39 +++++++++++++++++++++++++-------------- 3 files changed, 48 insertions(+), 15 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 7671530d6e4e..e30100597d0a 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1449,6 +1449,7 @@ struct bpf_prog_aux { bool dev_bound; /* Program is bound to the netdev. */ bool offload_requested; /* Program is bound and offloaded to the netdev. */ bool attach_btf_trace; /* true if attaching to BTF-enabled raw tp */ + bool attach_tracing_prog; /* true if tracing another tracing program */ bool func_proto_unreliable; bool sleepable; bool tail_call_reachable; diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 1bf9805ee185..d15f9998bc20 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2738,6 +2738,22 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) goto free_prog_sec; } + /* + * Bookkeeping for managing the program attachment chain. + * + * It might be tempting to set attach_tracing_prog flag at the attachment + * time, but this will not prevent from loading bunch of tracing prog + * first, then attach them one to another. + * + * The flag attach_tracing_prog is set for the whole program lifecycle, and + * doesn't have to be cleared in bpf_tracing_link_release, since tracing + * programs cannot change attachment target. + */ + if (type == BPF_PROG_TYPE_TRACING && dst_prog && + dst_prog->type == BPF_PROG_TYPE_TRACING) { + prog->aux->attach_tracing_prog = true; + } + /* find program type: socket_filter vs tracing_filter */ err = find_prog_type(type, prog); if (err < 0) @@ -3171,7 +3187,12 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, } if (tgt_prog_fd) { - /* For now we only allow new targets for BPF_PROG_TYPE_EXT */ + /* + * For now we only allow new targets for BPF_PROG_TYPE_EXT. If this + * part would be changed to implement the same for + * BPF_PROG_TYPE_TRACING, do not forget to update the way how + * attach_tracing_prog flag is set. + */ if (prog->type != BPF_PROG_TYPE_EXT) { err = -EINVAL; goto out_put_prog; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index d5f4ff1eb235..adbf330d364b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -20317,6 +20317,7 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, struct bpf_attach_target_info *tgt_info) { bool prog_extension = prog->type == BPF_PROG_TYPE_EXT; + bool prog_tracing = prog->type == BPF_PROG_TYPE_TRACING; const char prefix[] = "btf_trace_"; int ret = 0, subprog = -1, i; const struct btf_type *t; @@ -20387,10 +20388,21 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, bpf_log(log, "Can attach to only JITed progs\n"); return -EINVAL; } - if (tgt_prog->type == prog->type) { - /* Cannot fentry/fexit another fentry/fexit program. - * Cannot attach program extension to another extension. - * It's ok to attach fentry/fexit to extension program. + if (prog_tracing) { + if (aux->attach_tracing_prog) { + /* + * Target program is an fentry/fexit which is already attached + * to another tracing program. More levels of nesting + * attachment are not allowed. + */ + bpf_log(log, "Cannot nest tracing program attach more than once\n"); + return -EINVAL; + } + } else if (tgt_prog->type == prog->type) { + /* + * To avoid potential call chain cycles, prevent attaching of a + * program extension to another extension. It's ok to attach + * fentry/fexit to extension program. */ bpf_log(log, "Cannot recursively attach\n"); return -EINVAL; @@ -20403,16 +20415,15 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, * except fentry/fexit. The reason is the following. * The fentry/fexit programs are used for performance * analysis, stats and can be attached to any program - * type except themselves. When extension program is - * replacing XDP function it is necessary to allow - * performance analysis of all functions. Both original - * XDP program and its program extension. Hence - * attaching fentry/fexit to BPF_PROG_TYPE_EXT is - * allowed. If extending of fentry/fexit was allowed it - * would be possible to create long call chain - * fentry->extension->fentry->extension beyond - * reasonable stack size. Hence extending fentry is not - * allowed. + * type. When extension program is replacing XDP function + * it is necessary to allow performance analysis of all + * functions. Both original XDP program and its program + * extension. Hence attaching fentry/fexit to + * BPF_PROG_TYPE_EXT is allowed. If extending of + * fentry/fexit was allowed it would be possible to create + * long call chain fentry->extension->fentry->extension + * beyond reasonable stack size. Hence extending fentry + * is not allowed. */ bpf_log(log, "Cannot extend fentry/fexit\n"); return -EINVAL; -- cgit v1.2.3 From 715d82ba636cb3629a6e18a33bb9dbe53f9936ee Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 3 Jan 2024 20:05:46 +0100 Subject: bpf: Fix re-attachment branch in bpf_tracing_prog_attach The following case can cause a crash due to missing attach_btf: 1) load rawtp program 2) load fentry program with rawtp as target_fd 3) create tracing link for fentry program with target_fd = 0 4) repeat 3 In the end we have: - prog->aux->dst_trampoline == NULL - tgt_prog == NULL (because we did not provide target_fd to link_create) - prog->aux->attach_btf == NULL (the program was loaded with attach_prog_fd=X) - the program was loaded for tgt_prog but we have no way to find out which one BUG: kernel NULL pointer dereference, address: 0000000000000058 Call Trace: ? __die+0x20/0x70 ? page_fault_oops+0x15b/0x430 ? fixup_exception+0x22/0x330 ? exc_page_fault+0x6f/0x170 ? asm_exc_page_fault+0x22/0x30 ? bpf_tracing_prog_attach+0x279/0x560 ? btf_obj_id+0x5/0x10 bpf_tracing_prog_attach+0x439/0x560 __sys_bpf+0x1cf4/0x2de0 __x64_sys_bpf+0x1c/0x30 do_syscall_64+0x41/0xf0 entry_SYSCALL_64_after_hwframe+0x6e/0x76 Return -EINVAL in this situation. Fixes: f3a95075549e0 ("bpf: Allow trampoline re-attach for tracing and lsm programs") Cc: stable@vger.kernel.org Signed-off-by: Jiri Olsa Acked-by: Jiri Olsa Acked-by: Song Liu Signed-off-by: Dmitrii Dolgov <9erthalion6@gmail.com> Link: https://lore.kernel.org/r/20240103190559.14750-4-9erthalion6@gmail.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/syscall.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index d15f9998bc20..a1f18681721c 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3237,6 +3237,10 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, * * - if prog->aux->dst_trampoline and tgt_prog is NULL, the program * was detached and is going for re-attachment. + * + * - if prog->aux->dst_trampoline is NULL and tgt_prog and prog->aux->attach_btf + * are NULL, then program was already attached and user did not provide + * tgt_prog_fd so we have no way to find out or create trampoline */ if (!prog->aux->dst_trampoline && !tgt_prog) { /* @@ -3250,6 +3254,11 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, err = -EINVAL; goto out_unlock; } + /* We can allow re-attach only if we have valid attach_btf. */ + if (!prog->aux->attach_btf) { + err = -EINVAL; + goto out_unlock; + } btf_id = prog->aux->attach_btf_id; key = bpf_trampoline_compute_key(NULL, prog->aux->attach_btf, btf_id); } -- cgit v1.2.3 From 22c7fa171a02d310e3a3f6ed46a698ca8a0060ed Mon Sep 17 00:00:00 2001 From: Hao Sun Date: Mon, 15 Jan 2024 09:20:27 +0100 Subject: bpf: Reject variable offset alu on PTR_TO_FLOW_KEYS For PTR_TO_FLOW_KEYS, check_flow_keys_access() only uses fixed off for validation. However, variable offset ptr alu is not prohibited for this ptr kind. So the variable offset is not checked. The following prog is accepted: func#0 @0 0: R1=ctx() R10=fp0 0: (bf) r6 = r1 ; R1=ctx() R6_w=ctx() 1: (79) r7 = *(u64 *)(r6 +144) ; R6_w=ctx() R7_w=flow_keys() 2: (b7) r8 = 1024 ; R8_w=1024 3: (37) r8 /= 1 ; R8_w=scalar() 4: (57) r8 &= 1024 ; R8_w=scalar(smin=smin32=0, smax=umax=smax32=umax32=1024,var_off=(0x0; 0x400)) 5: (0f) r7 += r8 mark_precise: frame0: last_idx 5 first_idx 0 subseq_idx -1 mark_precise: frame0: regs=r8 stack= before 4: (57) r8 &= 1024 mark_precise: frame0: regs=r8 stack= before 3: (37) r8 /= 1 mark_precise: frame0: regs=r8 stack= before 2: (b7) r8 = 1024 6: R7_w=flow_keys(smin=smin32=0,smax=umax=smax32=umax32=1024,var_off =(0x0; 0x400)) R8_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=1024, var_off=(0x0; 0x400)) 6: (79) r0 = *(u64 *)(r7 +0) ; R0_w=scalar() 7: (95) exit This prog loads flow_keys to r7, and adds the variable offset r8 to r7, and finally causes out-of-bounds access: BUG: unable to handle page fault for address: ffffc90014c80038 [...] Call Trace: bpf_dispatcher_nop_func include/linux/bpf.h:1231 [inline] __bpf_prog_run include/linux/filter.h:651 [inline] bpf_prog_run include/linux/filter.h:658 [inline] bpf_prog_run_pin_on_cpu include/linux/filter.h:675 [inline] bpf_flow_dissect+0x15f/0x350 net/core/flow_dissector.c:991 bpf_prog_test_run_flow_dissector+0x39d/0x620 net/bpf/test_run.c:1359 bpf_prog_test_run kernel/bpf/syscall.c:4107 [inline] __sys_bpf+0xf8f/0x4560 kernel/bpf/syscall.c:5475 __do_sys_bpf kernel/bpf/syscall.c:5561 [inline] __se_sys_bpf kernel/bpf/syscall.c:5559 [inline] __x64_sys_bpf+0x73/0xb0 kernel/bpf/syscall.c:5559 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b Fix this by rejecting ptr alu with variable offset on flow_keys. Applying the patch rejects the program with "R7 pointer arithmetic on flow_keys prohibited". Fixes: d58e468b1112 ("flow_dissector: implements flow dissector BPF hook") Signed-off-by: Hao Sun Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20240115082028.9992-1-sunhao.th@gmail.com --- kernel/bpf/verifier.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index adbf330d364b..65f598694d55 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -12826,6 +12826,10 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, } switch (base_type(ptr_reg->type)) { + case PTR_TO_FLOW_KEYS: + if (known) + break; + fallthrough; case CONST_PTR_TO_MAP: /* smin_val represents the known value */ if (known && smin_val == 0 && opcode == BPF_ADD) -- cgit v1.2.3 From 66967a32d3b16ed447e76fed4d946bab52e43d86 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 17 Jan 2024 19:31:40 -0800 Subject: bpf: extract bpf_ctx_convert_map logic and make it more reusable Refactor btf_get_prog_ctx_type() a bit to allow reuse of bpf_ctx_convert_map logic in more than one places. Simplify interface by returning btf_type instead of btf_member (field reference in BTF). To do the above we need to touch and start untangling btf_translate_to_vmlinux() implementation. We do the bare minimum to not regress anything for btf_translate_to_vmlinux(), but its implementation is very questionable for what it claims to be doing. Mapping kfunc argument types to kernel corresponding types conceptually is quite different from recognizing program context types. Fixing this is out of scope for this change though. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240118033143.3384355-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/btf.h | 2 +- kernel/bpf/btf.c | 71 +++++++++++++++++++++++++++++++++-------------------- 2 files changed, 46 insertions(+), 27 deletions(-) (limited to 'kernel/bpf') diff --git a/include/linux/btf.h b/include/linux/btf.h index 59d404e22814..cf5c6ff48981 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -512,7 +512,7 @@ s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id); int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt, struct module *owner); struct btf_struct_meta *btf_find_struct_meta(const struct btf *btf, u32 btf_id); -const struct btf_member * +const struct btf_type * btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf, const struct btf_type *t, enum bpf_prog_type prog_type, int arg); diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 51e8b4bee0c8..10ac9efc662d 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -5615,21 +5615,46 @@ static u8 bpf_ctx_convert_map[] = { #undef BPF_MAP_TYPE #undef BPF_LINK_TYPE -const struct btf_member * -btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf, - const struct btf_type *t, enum bpf_prog_type prog_type, - int arg) +static const struct btf_type *find_canonical_prog_ctx_type(enum bpf_prog_type prog_type) { const struct btf_type *conv_struct; - const struct btf_type *ctx_struct; const struct btf_member *ctx_type; - const char *tname, *ctx_tname; conv_struct = bpf_ctx_convert.t; - if (!conv_struct) { - bpf_log(log, "btf_vmlinux is malformed\n"); + if (!conv_struct) return NULL; - } + /* prog_type is valid bpf program type. No need for bounds check. */ + ctx_type = btf_type_member(conv_struct) + bpf_ctx_convert_map[prog_type] * 2; + /* ctx_type is a pointer to prog_ctx_type in vmlinux. + * Like 'struct __sk_buff' + */ + return btf_type_by_id(btf_vmlinux, ctx_type->type); +} + +static int find_kern_ctx_type_id(enum bpf_prog_type prog_type) +{ + const struct btf_type *conv_struct; + const struct btf_member *ctx_type; + + conv_struct = bpf_ctx_convert.t; + if (!conv_struct) + return -EFAULT; + /* prog_type is valid bpf program type. No need for bounds check. */ + ctx_type = btf_type_member(conv_struct) + bpf_ctx_convert_map[prog_type] * 2 + 1; + /* ctx_type is a pointer to prog_ctx_type in vmlinux. + * Like 'struct sk_buff' + */ + return ctx_type->type; +} + +const struct btf_type * +btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf, + const struct btf_type *t, enum bpf_prog_type prog_type, + int arg) +{ + const struct btf_type *ctx_type; + const char *tname, *ctx_tname; + t = btf_type_by_id(btf, t->type); while (btf_type_is_modifier(t)) t = btf_type_by_id(btf, t->type); @@ -5646,17 +5671,15 @@ btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf, bpf_log(log, "arg#%d struct doesn't have a name\n", arg); return NULL; } - /* prog_type is valid bpf program type. No need for bounds check. */ - ctx_type = btf_type_member(conv_struct) + bpf_ctx_convert_map[prog_type] * 2; - /* ctx_struct is a pointer to prog_ctx_type in vmlinux. - * Like 'struct __sk_buff' - */ - ctx_struct = btf_type_by_id(btf_vmlinux, ctx_type->type); - if (!ctx_struct) + + ctx_type = find_canonical_prog_ctx_type(prog_type); + if (!ctx_type) { + bpf_log(log, "btf_vmlinux is malformed\n"); /* should not happen */ return NULL; + } again: - ctx_tname = btf_name_by_offset(btf_vmlinux, ctx_struct->name_off); + ctx_tname = btf_name_by_offset(btf_vmlinux, ctx_type->name_off); if (!ctx_tname) { /* should not happen */ bpf_log(log, "Please fix kernel include/linux/bpf_types.h\n"); @@ -5677,10 +5700,10 @@ again: /* bpf_user_pt_regs_t is a typedef, so resolve it to * underlying struct and check name again */ - if (!btf_type_is_modifier(ctx_struct)) + if (!btf_type_is_modifier(ctx_type)) return NULL; - while (btf_type_is_modifier(ctx_struct)) - ctx_struct = btf_type_by_id(btf_vmlinux, ctx_struct->type); + while (btf_type_is_modifier(ctx_type)) + ctx_type = btf_type_by_id(btf_vmlinux, ctx_type->type); goto again; } return ctx_type; @@ -5692,13 +5715,9 @@ static int btf_translate_to_vmlinux(struct bpf_verifier_log *log, enum bpf_prog_type prog_type, int arg) { - const struct btf_member *prog_ctx_type, *kern_ctx_type; - - prog_ctx_type = btf_get_prog_ctx_type(log, btf, t, prog_type, arg); - if (!prog_ctx_type) + if (!btf_get_prog_ctx_type(log, btf, t, prog_type, arg)) return -ENOENT; - kern_ctx_type = prog_ctx_type + 1; - return kern_ctx_type->type; + return find_kern_ctx_type_id(prog_type); } int get_kern_ctx_btf_id(struct bpf_verifier_log *log, enum bpf_prog_type prog_type) -- cgit v1.2.3 From 0ba971511d16603599f947459e59b435cc465b0d Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 17 Jan 2024 19:31:41 -0800 Subject: bpf: enforce types for __arg_ctx-tagged arguments in global subprogs Add enforcement of expected types for context arguments tagged with arg:ctx (__arg_ctx) tag. First, any program type will accept generic `void *` context type when combined with __arg_ctx tag. Besides accepting "canonical" struct names and `void *`, for a bunch of program types for which program context is actually a named struct, we allows a bunch of pragmatic exceptions to match real-world and expected usage: - for both kprobes and perf_event we allow `bpf_user_pt_regs_t *` as canonical context argument type, where `bpf_user_pt_regs_t` is a *typedef*, not a struct; - for kprobes, we also always accept `struct pt_regs *`, as that's what actually is passed as a context to any kprobe program; - for perf_event, we resolve typedefs (unless it's `bpf_user_pt_regs_t`) down to actual struct type and accept `struct pt_regs *`, or `struct user_pt_regs *`, or `struct user_regs_struct *`, depending on the actual struct type kernel architecture points `bpf_user_pt_regs_t` typedef to; otherwise, canonical `struct bpf_perf_event_data *` is expected; - for raw_tp/raw_tp.w programs, `u64/long *` are accepted, as that's what's expected with BPF_PROG() usage; otherwise, canonical `struct bpf_raw_tracepoint_args *` is expected; - tp_btf supports both `struct bpf_raw_tracepoint_args *` and `u64 *` formats, both are coded as expections as tp_btf is actually a TRACING program type, which has no canonical context type; - iterator programs accept `struct bpf_iter__xxx *` structs, currently with no further iterator-type specific enforcement; - fentry/fexit/fmod_ret/lsm/struct_ops all accept `u64 *`; - classic tracepoint programs, as well as syscall and freplace programs allow any user-provided type. In all other cases kernel will enforce exact match of struct name to expected canonical type. And if user-provided type doesn't match that expectation, verifier will emit helpful message with expected type name. Note a bit unnatural way the check is done after processing all the arguments. This is done to avoid conflict between bpf and bpf-next trees. Once trees converge, a small follow up patch will place a simple btf_validate_prog_ctx_type() check into a proper ARG_PTR_TO_CTX branch (which bpf-next tree patch refactored already), removing duplicated arg:ctx detection logic. Suggested-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240118033143.3384355-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/btf.c | 160 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 160 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 10ac9efc662d..596471189176 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -5709,6 +5709,149 @@ again: return ctx_type; } +/* forward declarations for arch-specific underlying types of + * bpf_user_pt_regs_t; this avoids the need for arch-specific #ifdef + * compilation guards below for BPF_PROG_TYPE_PERF_EVENT checks, but still + * works correctly with __builtin_types_compatible_p() on respective + * architectures + */ +struct user_regs_struct; +struct user_pt_regs; + +static int btf_validate_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf, + const struct btf_type *t, int arg, + enum bpf_prog_type prog_type, + enum bpf_attach_type attach_type) +{ + const struct btf_type *ctx_type; + const char *tname, *ctx_tname; + + if (!btf_is_ptr(t)) { + bpf_log(log, "arg#%d type isn't a pointer\n", arg); + return -EINVAL; + } + t = btf_type_by_id(btf, t->type); + + /* KPROBE and PERF_EVENT programs allow bpf_user_pt_regs_t typedef */ + if (prog_type == BPF_PROG_TYPE_KPROBE || prog_type == BPF_PROG_TYPE_PERF_EVENT) { + while (btf_type_is_modifier(t) && !btf_type_is_typedef(t)) + t = btf_type_by_id(btf, t->type); + + if (btf_type_is_typedef(t)) { + tname = btf_name_by_offset(btf, t->name_off); + if (tname && strcmp(tname, "bpf_user_pt_regs_t") == 0) + return 0; + } + } + + /* all other program types don't use typedefs for context type */ + while (btf_type_is_modifier(t)) + t = btf_type_by_id(btf, t->type); + + /* `void *ctx __arg_ctx` is always valid */ + if (btf_type_is_void(t)) + return 0; + + tname = btf_name_by_offset(btf, t->name_off); + if (str_is_empty(tname)) { + bpf_log(log, "arg#%d type doesn't have a name\n", arg); + return -EINVAL; + } + + /* special cases */ + switch (prog_type) { + case BPF_PROG_TYPE_KPROBE: + if (__btf_type_is_struct(t) && strcmp(tname, "pt_regs") == 0) + return 0; + break; + case BPF_PROG_TYPE_PERF_EVENT: + if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct pt_regs) && + __btf_type_is_struct(t) && strcmp(tname, "pt_regs") == 0) + return 0; + if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct user_pt_regs) && + __btf_type_is_struct(t) && strcmp(tname, "user_pt_regs") == 0) + return 0; + if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct user_regs_struct) && + __btf_type_is_struct(t) && strcmp(tname, "user_regs_struct") == 0) + return 0; + break; + case BPF_PROG_TYPE_RAW_TRACEPOINT: + case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE: + /* allow u64* as ctx */ + if (btf_is_int(t) && t->size == 8) + return 0; + break; + case BPF_PROG_TYPE_TRACING: + switch (attach_type) { + case BPF_TRACE_RAW_TP: + /* tp_btf program is TRACING, so need special case here */ + if (__btf_type_is_struct(t) && + strcmp(tname, "bpf_raw_tracepoint_args") == 0) + return 0; + /* allow u64* as ctx */ + if (btf_is_int(t) && t->size == 8) + return 0; + break; + case BPF_TRACE_ITER: + /* allow struct bpf_iter__xxx types only */ + if (__btf_type_is_struct(t) && + strncmp(tname, "bpf_iter__", sizeof("bpf_iter__") - 1) == 0) + return 0; + break; + case BPF_TRACE_FENTRY: + case BPF_TRACE_FEXIT: + case BPF_MODIFY_RETURN: + /* allow u64* as ctx */ + if (btf_is_int(t) && t->size == 8) + return 0; + break; + default: + break; + } + break; + case BPF_PROG_TYPE_LSM: + case BPF_PROG_TYPE_STRUCT_OPS: + /* allow u64* as ctx */ + if (btf_is_int(t) && t->size == 8) + return 0; + break; + case BPF_PROG_TYPE_TRACEPOINT: + case BPF_PROG_TYPE_SYSCALL: + case BPF_PROG_TYPE_EXT: + return 0; /* anything goes */ + default: + break; + } + + ctx_type = find_canonical_prog_ctx_type(prog_type); + if (!ctx_type) { + /* should not happen */ + bpf_log(log, "btf_vmlinux is malformed\n"); + return -EINVAL; + } + + /* resolve typedefs and check that underlying structs are matching as well */ + while (btf_type_is_modifier(ctx_type)) + ctx_type = btf_type_by_id(btf_vmlinux, ctx_type->type); + + /* if program type doesn't have distinctly named struct type for + * context, then __arg_ctx argument can only be `void *`, which we + * already checked above + */ + if (!__btf_type_is_struct(ctx_type)) { + bpf_log(log, "arg#%d should be void pointer\n", arg); + return -EINVAL; + } + + ctx_tname = btf_name_by_offset(btf_vmlinux, ctx_type->name_off); + if (!__btf_type_is_struct(t) || strcmp(ctx_tname, tname) != 0) { + bpf_log(log, "arg#%d should be `struct %s *`\n", arg, ctx_tname); + return -EINVAL; + } + + return 0; +} + static int btf_translate_to_vmlinux(struct bpf_verifier_log *log, struct btf *btf, const struct btf_type *t, @@ -6953,6 +7096,23 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) return -EINVAL; } + for (i = 0; i < nargs; i++) { + const char *tag; + + if (sub->args[i].arg_type != ARG_PTR_TO_CTX) + continue; + + /* check if arg has "arg:ctx" tag */ + t = btf_type_by_id(btf, args[i].type); + tag = btf_find_decl_tag_value(btf, fn_t, i, "arg:"); + if (IS_ERR_OR_NULL(tag) || strcmp(tag, "ctx") != 0) + continue; + + if (btf_validate_prog_ctx_type(log, btf, t, i, prog_type, + prog->expected_attach_type)) + return -EINVAL; + } + sub->arg_cnt = nargs; sub->args_cached = true; -- cgit v1.2.3