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[ Upstream commit 5534e58f2e9bd72b253d033ee0af6e68eb8ac96b ]
When reg->type is CONST_PTR_TO_MAP, it can not be null. However the
verifier explores the branches under rX == 0 in check_cond_jmp_op()
even if reg->type is CONST_PTR_TO_MAP, because it was not checked for
in reg_not_null().
Fix this by adding CONST_PTR_TO_MAP to the set of types that are
considered non nullable in reg_not_null().
An old "unpriv: cmp map pointer with zero" selftest fails with this
change, because now early out correctly triggers in
check_cond_jmp_op(), making the verification to pass.
In practice verifier may allow pointer to null comparison in unpriv,
since in many cases the relevant branch and comparison op are removed
as dead code. So change the expected test result to __success_unpriv.
Signed-off-by: Ihor Solodrai <isolodrai@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250609183024.359974-2-isolodrai@meta.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 2b03164eee20eac7ce0fe3aa4fbda7efc1e5427a ]
The usermode driver framework is not used anymore by the BPF
preload code.
Fixes: cb80ddc67152 ("bpf: Convert bpf_preload.ko to use light skeleton.")
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/bpf/20250721-remove-usermode-driver-v1-1-0d0083334382@linutronix.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit f8242745871f81a3ac37f9f51853d12854fd0b58 ]
static const char fmt[] = "%p%";
bpf_trace_printk(fmt, sizeof(fmt));
The above BPF program isn't rejected and causes a kernel warning at
runtime:
Please remove unsupported %\x00 in format string
WARNING: CPU: 1 PID: 7244 at lib/vsprintf.c:2680 format_decode+0x49c/0x5d0
This happens because bpf_bprintf_prepare skips over the second %,
detected as punctuation, while processing %p. This patch fixes it by
not skipping over punctuation. %\x00 is then processed in the next
iteration and rejected.
Reported-by: syzbot+e2c932aec5c8a6e1d31c@syzkaller.appspotmail.com
Fixes: 48cac3f4a96d ("bpf: Implement formatted output helpers with bstr_printf")
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/r/a0e06cc479faec9e802ae51ba5d66420523251ee.1751395489.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit d4adf1c9ee7722545450608bcb095fb31512f0c6 ]
BPF_MAP_TYPE_LRU_HASH can recycle most recent elements well before the
map is full, due to percpu reservations and force shrink before
neighbor stealing. Once a CPU is unable to borrow from the global map,
it will once steal one elem from a neighbor and after that each time
flush this one element to the global list and immediately recycle it.
Batch value LOCAL_FREE_TARGET (128) will exhaust a 10K element map
with 79 CPUs. CPU 79 will observe this behavior even while its
neighbors hold 78 * 127 + 1 * 15 == 9921 free elements (99%).
CPUs need not be active concurrently. The issue can appear with
affinity migration, e.g., irqbalance. Each CPU can reserve and then
hold onto its 128 elements indefinitely.
Avoid global list exhaustion by limiting aggregate percpu caches to
half of map size, by adjusting LOCAL_FREE_TARGET based on cpu count.
This change has no effect on sufficiently large tables.
Similar to LOCAL_NR_SCANS and lru->nr_scans, introduce a map variable
lru->free_target. The extra field fits in a hole in struct bpf_lru.
The cacheline is already warm where read in the hot path. The field is
only accessed with the lru lock held.
Tested-by: Anton Protopopov <a.s.protopopov@gmail.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://lore.kernel.org/r/20250618215803.3587312-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit d4965578267e2e81f67c86e2608481e77e9c8569 ]
bpf_map_lookup_percpu_elem() helper is also available for sleepable bpf
program. When BPF JIT is disabled or under 32-bit host,
bpf_map_lookup_percpu_elem() will not be inlined. Using it in a
sleepable bpf program will trigger the warning in
bpf_map_lookup_percpu_elem(), because the bpf program only holds
rcu_read_lock_trace lock. Therefore, add the missed check.
Reported-by: syzbot+dce5aae19ae4d6399986@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/bpf/000000000000176a130617420310@google.com/
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250526062534.1105938-1-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 86bc9c742426a16b52a10ef61f5b721aecca2344 ]
syzkaller reported an issue:
WARNING: CPU: 3 PID: 217 at kernel/bpf/core.c:2357 __bpf_prog_ret0_warn+0xa/0x20 kernel/bpf/core.c:2357
Modules linked in:
CPU: 3 UID: 0 PID: 217 Comm: kworker/u32:6 Not tainted 6.15.0-rc4-syzkaller-00040-g8bac8898fe39
RIP: 0010:__bpf_prog_ret0_warn+0xa/0x20 kernel/bpf/core.c:2357
Call Trace:
<TASK>
bpf_dispatcher_nop_func include/linux/bpf.h:1316 [inline]
__bpf_prog_run include/linux/filter.h:718 [inline]
bpf_prog_run include/linux/filter.h:725 [inline]
cls_bpf_classify+0x74a/0x1110 net/sched/cls_bpf.c:105
...
When creating bpf program, 'fp->jit_requested' depends on bpf_jit_enable.
This issue is triggered because of CONFIG_BPF_JIT_ALWAYS_ON is not set
and bpf_jit_enable is set to 1, causing the arch to attempt JIT the prog,
but jit failed due to FAULT_INJECTION. As a result, incorrectly
treats the program as valid, when the program runs it calls
`__bpf_prog_ret0_warn` and triggers the WARN_ON_ONCE(1).
Reported-by: syzbot+0903f6d7f285e41cdf10@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/bpf/6816e34e.a70a0220.254cdc.002c.GAE@google.com
Fixes: fa9dd599b4da ("bpf: get rid of pure_initcall dependency to enable jits")
Signed-off-by: KaFai Wan <mannkafai@gmail.com>
Link: https://lore.kernel.org/r/20250526133358.2594176-1-mannkafai@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 714070c4cb7a10ff57450a618a936775f3036245 ]
In the current implementation if the program is dev-bound to a specific
device, it will not be possible to perform XDP_REDIRECT into a DEVMAP
or CPUMAP even if the program is running in the driver NAPI context and
it is not attached to any map entry. This seems in contrast with the
explanation available in bpf_prog_map_compatible routine.
Fix the issue introducing __bpf_prog_map_compatible utility routine in
order to avoid bpf_prog_is_dev_bound() check running bpf_check_tail_call()
at program load time (bpf_prog_select_runtime()).
Continue forbidding to attach a dev-bound program to XDP maps
(BPF_MAP_TYPE_PROG_ARRAY, BPF_MAP_TYPE_DEVMAP and BPF_MAP_TYPE_CPUMAP).
Fixes: 3d76a4d3d4e59 ("bpf: XDP metadata RX kfuncs")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 9e63fdb0cbdf3268c86638a8274f4d5549a82820 ]
verifier.c:is_state_visited() uses RANGE_WITHIN states comparison rules
for cached states that have loop_entry with non-zero branches count
(meaning that loop_entry's verification is not yet done).
The RANGE_WITHIN rules in regsafe()/stacksafe() require register and
stack objects types to be identical in current and old states.
verifier.c:clean_live_states() replaces registers and stack spills
with NOT_INIT/STACK_INVALID marks, if these registers/stack spills are
not read in any child state. This means that clean_live_states() works
against loop convergence logic under some conditions. See selftest in
the next patch for a specific example.
Mitigate this by prohibiting clean_verifier_state() when
state->loop_entry->branches > 0.
This undoes negative verification performance impact of the
copy_verifier_state() fix from the previous patch.
Below is comparison between master and current patch.
selftests:
File Program Insns (A) Insns (B) Insns (DIFF) States (A) States (B) States (DIFF)
---------------------------------- ---------------------------- --------- --------- --------------- ---------- ---------- --------------
arena_htab.bpf.o arena_htab_llvm 717 423 -294 (-41.00%) 57 37 -20 (-35.09%)
arena_htab_asm.bpf.o arena_htab_asm 597 445 -152 (-25.46%) 47 37 -10 (-21.28%)
arena_list.bpf.o arena_list_add 1493 1822 +329 (+22.04%) 30 37 +7 (+23.33%)
arena_list.bpf.o arena_list_del 309 261 -48 (-15.53%) 23 15 -8 (-34.78%)
iters.bpf.o checkpoint_states_deletion 18125 22154 +4029 (+22.23%) 818 918 +100 (+12.22%)
iters.bpf.o iter_nested_deeply_iters 593 367 -226 (-38.11%) 67 43 -24 (-35.82%)
iters.bpf.o iter_nested_iters 813 772 -41 (-5.04%) 79 72 -7 (-8.86%)
iters.bpf.o iter_subprog_check_stacksafe 155 135 -20 (-12.90%) 15 14 -1 (-6.67%)
iters.bpf.o iter_subprog_iters 1094 808 -286 (-26.14%) 88 68 -20 (-22.73%)
iters.bpf.o loop_state_deps2 479 356 -123 (-25.68%) 46 35 -11 (-23.91%)
iters.bpf.o triple_continue 35 31 -4 (-11.43%) 3 3 +0 (+0.00%)
kmem_cache_iter.bpf.o open_coded_iter 63 59 -4 (-6.35%) 7 6 -1 (-14.29%)
mptcp_subflow.bpf.o _getsockopt_subflow 501 446 -55 (-10.98%) 25 23 -2 (-8.00%)
pyperf600_iter.bpf.o on_event 12339 6379 -5960 (-48.30%) 441 286 -155 (-35.15%)
verifier_bits_iter.bpf.o max_words 92 84 -8 (-8.70%) 8 7 -1 (-12.50%)
verifier_iterating_callbacks.bpf.o cond_break2 113 192 +79 (+69.91%) 12 21 +9 (+75.00%)
sched_ext:
File Program Insns (A) Insns (B) Insns (DIFF) States (A) States (B) States (DIFF)
----------------- ---------------------- --------- --------- ----------------- ---------- ---------- ----------------
bpf.bpf.o layered_dispatch 11485 9039 -2446 (-21.30%) 848 662 -186 (-21.93%)
bpf.bpf.o layered_dump 7422 5022 -2400 (-32.34%) 681 298 -383 (-56.24%)
bpf.bpf.o layered_enqueue 16854 13753 -3101 (-18.40%) 1611 1308 -303 (-18.81%)
bpf.bpf.o layered_init 1000001 5549 -994452 (-99.45%) 84672 523 -84149 (-99.38%)
bpf.bpf.o layered_runnable 3149 1899 -1250 (-39.70%) 288 151 -137 (-47.57%)
bpf.bpf.o p2dq_init 2343 1936 -407 (-17.37%) 201 170 -31 (-15.42%)
bpf.bpf.o refresh_layer_cpumasks 16487 1285 -15202 (-92.21%) 1770 120 -1650 (-93.22%)
bpf.bpf.o rusty_select_cpu 1937 1386 -551 (-28.45%) 177 125 -52 (-29.38%)
scx_central.bpf.o central_dispatch 636 600 -36 (-5.66%) 63 59 -4 (-6.35%)
scx_central.bpf.o central_init 913 632 -281 (-30.78%) 48 39 -9 (-18.75%)
scx_nest.bpf.o nest_init 636 601 -35 (-5.50%) 60 58 -2 (-3.33%)
scx_pair.bpf.o pair_dispatch 1000001 1914 -998087 (-99.81%) 58169 142 -58027 (-99.76%)
scx_qmap.bpf.o qmap_dispatch 2393 2187 -206 (-8.61%) 196 174 -22 (-11.22%)
scx_qmap.bpf.o qmap_init 16367 22777 +6410 (+39.16%) 603 768 +165 (+27.36%)
'layered_init' and 'pair_dispatch' hit 1M on master, but are verified
ok with this patch.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250215110411.3236773-4-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 4b82b181a26cff8bf7adc3a85a88d121d92edeaf ]
Currently for bpf progs in a cgroup hierarchy, the effective prog array
is computed from bottom cgroup to upper cgroups (post-ordering). For
example, the following cgroup hierarchy
root cgroup: p1, p2
subcgroup: p3, p4
have BPF_F_ALLOW_MULTI for both cgroup levels.
The effective cgroup array ordering looks like
p3 p4 p1 p2
and at run time, progs will execute based on that order.
But in some cases, it is desirable to have root prog executes earlier than
children progs (pre-ordering). For example,
- prog p1 intends to collect original pkt dest addresses.
- prog p3 will modify original pkt dest addresses to a proxy address for
security reason.
The end result is that prog p1 gets proxy address which is not what it
wants. Putting p1 to every child cgroup is not desirable either as it
will duplicate itself in many child cgroups. And this is exactly a use case
we are encountering in Meta.
To fix this issue, let us introduce a flag BPF_F_PREORDER. If the flag
is specified at attachment time, the prog has higher priority and the
ordering with that flag will be from top to bottom (pre-ordering).
For example, in the above example,
root cgroup: p1, p2
subcgroup: p3, p4
Let us say p2 and p4 are marked with BPF_F_PREORDER. The final
effective array ordering will be
p2 p4 p3 p1
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20250224230116.283071-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 07651ccda9ff10a8ca427670cdd06ce2c8e4269c ]
Return prog's btf_id from bpf_prog_get_info_by_fd regardless of capable
check. This patch enables scenario, when freplace program, running
from user namespace, requires to query target prog's btf.
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/bpf/20250317174039.161275-3-mykyta.yatsenko5@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 75673fda0c557ae26078177dd14d4857afbf128d ]
The _safe variant used here gets the next element before running the callback,
avoiding the endless loop condition.
Signed-off-by: Brandon Kammerdiener <brandon.kammerdiener@intel.com>
Link: https://lore.kernel.org/r/20250424153246.141677-2-brandon.kammerdiener@intel.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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commit ac6542ad92759cda383ad62b4e4cbfc28136abc1 upstream.
bpf_prog_aux->func field might be NULL if program does not have
subprograms except for main sub-program. The fixed commit does
bpf_prog_aux->func access unconditionally, which might lead to null
pointer dereference.
The bug could be triggered by replacing the following BPF program:
SEC("tc")
int main_changes(struct __sk_buff *sk)
{
bpf_skb_pull_data(sk, 0);
return 0;
}
With the following BPF program:
SEC("freplace")
long changes_pkt_data(struct __sk_buff *sk)
{
return bpf_skb_pull_data(sk, 0);
}
bpf_prog_aux instance itself represents the main sub-program,
use this property to fix the bug.
Fixes: 81f6d0530ba0 ("bpf: check changes_pkt_data property for extension programs")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202412111822.qGw6tOyB-lkp@intel.com/
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241212070711.427443-1-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 81f6d0530ba031b5f038a091619bf2ff29568852 upstream.
When processing calls to global sub-programs, verifier decides whether
to invalidate all packet pointers in current state depending on the
changes_pkt_data property of the global sub-program.
Because of this, an extension program replacing a global sub-program
must be compatible with changes_pkt_data property of the sub-program
being replaced.
This commit:
- adds changes_pkt_data flag to struct bpf_prog_aux:
- this flag is set in check_cfg() for main sub-program;
- in jit_subprogs() for other sub-programs;
- modifies bpf_check_attach_btf_id() to check changes_pkt_data flag;
- moves call to check_attach_btf_id() after the call to check_cfg(),
because it needs changes_pkt_data flag to be set:
bpf_check:
... ...
- check_attach_btf_id resolve_pseudo_ldimm64
resolve_pseudo_ldimm64 --> bpf_prog_is_offloaded
bpf_prog_is_offloaded check_cfg
check_cfg + check_attach_btf_id
... ...
The following fields are set by check_attach_btf_id():
- env->ops
- prog->aux->attach_btf_trace
- prog->aux->attach_func_name
- prog->aux->attach_func_proto
- prog->aux->dst_trampoline
- prog->aux->mod
- prog->aux->saved_dst_attach_type
- prog->aux->saved_dst_prog_type
- prog->expected_attach_type
Neither of these fields are used by resolve_pseudo_ldimm64() or
bpf_prog_offload_verifier_prep() (for netronome and netdevsim
drivers), so the reordering is safe.
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241210041100.1898468-6-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
[ shung-hsi.yu: adapt to missing fields in "struct bpf_prog_aux". Context
difference in jit_subprogs() because BPF Exception is not supported. Context
difference in bpf_check() because commit 5b5f51bff1b6 "bpf:
no_caller_saved_registers attribute for helper calls" is not present. ]
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 51081a3f25c742da5a659d7fc6fd77ebfdd555be upstream.
When processing calls to certain helpers, verifier invalidates all
packet pointers in a current state. For example, consider the
following program:
__attribute__((__noinline__))
long skb_pull_data(struct __sk_buff *sk, __u32 len)
{
return bpf_skb_pull_data(sk, len);
}
SEC("tc")
int test_invalidate_checks(struct __sk_buff *sk)
{
int *p = (void *)(long)sk->data;
if ((void *)(p + 1) > (void *)(long)sk->data_end) return TCX_DROP;
skb_pull_data(sk, 0);
*p = 42;
return TCX_PASS;
}
After a call to bpf_skb_pull_data() the pointer 'p' can't be used
safely. See function filter.c:bpf_helper_changes_pkt_data() for a list
of such helpers.
At the moment verifier invalidates packet pointers when processing
helper function calls, and does not traverse global sub-programs when
processing calls to global sub-programs. This means that calls to
helpers done from global sub-programs do not invalidate pointers in
the caller state. E.g. the program above is unsafe, but is not
rejected by verifier.
This commit fixes the omission by computing field
bpf_subprog_info->changes_pkt_data for each sub-program before main
verification pass.
changes_pkt_data should be set if:
- subprogram calls helper for which bpf_helper_changes_pkt_data
returns true;
- subprogram calls a global function,
for which bpf_subprog_info->changes_pkt_data should be set.
The verifier.c:check_cfg() pass is modified to compute this
information. The commit relies on depth first instruction traversal
done by check_cfg() and absence of recursive function calls:
- check_cfg() would eventually visit every call to subprogram S in a
state when S is fully explored;
- when S is fully explored:
- every direct helper call within S is explored
(and thus changes_pkt_data is set if needed);
- every call to subprogram S1 called by S was visited with S1 fully
explored (and thus S inherits changes_pkt_data from S1).
The downside of such approach is that dead code elimination is not
taken into account: if a helper call inside global function is dead
because of current configuration, verifier would conservatively assume
that the call occurs for the purpose of the changes_pkt_data
computation.
Reported-by: Nick Zavaritsky <mejedi@gmail.com>
Closes: https://lore.kernel.org/bpf/0498CA22-5779-4767-9C0C-A9515CEA711F@gmail.com/
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241210041100.1898468-4-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
[shung-hsi.yu: do not use bitfield in "struct bpf_subprog_info" because commit
406a6fa44bfb ("bpf: use bitfields for simple per-subprog bool flags") is not
present and minor context difference in check_func_call() because commit
491dd8edecbc ("bpf: Emit global subprog name in verifier logs") is not present. ]
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit b238e187b4a2d3b54d80aec05a9cab6466b79dde upstream.
Use BPF helper number instead of function pointer in
bpf_helper_changes_pkt_data(). This would simplify usage of this
function in verifier.c:check_cfg() (in a follow-up patch),
where only helper number is easily available and there is no real need
to lookup helper proto.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241210041100.1898468-3-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 27e88bc4df1d80888fe1aaca786a7cc6e69587e2 upstream.
Add a utility function, looking for a subprogram containing a given
instruction index, rewrite find_subprog() to use this function.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241210041100.1898468-2-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit cfe816d469dce9c0864062cf65dd7b3c42adc6f8 ]
If we attach fexit/fmod_ret to __noreturn functions, it will cause an
issue that the bpf trampoline image will be left over even if the bpf
link has been destroyed. Take attaching do_exit() with fexit for example.
The fexit works as follows,
bpf_trampoline
+ __bpf_tramp_enter
+ percpu_ref_get(&tr->pcref);
+ call do_exit()
+ __bpf_tramp_exit
+ percpu_ref_put(&tr->pcref);
Since do_exit() never returns, the refcnt of the trampoline image is
never decremented, preventing it from being freed. That can be verified
with as follows,
$ bpftool link show <<<< nothing output
$ grep "bpf_trampoline_[0-9]" /proc/kallsyms
ffffffffc04cb000 t bpf_trampoline_6442526459 [bpf] <<<< leftover
In this patch, all functions annotated with __noreturn are rejected, except
for the following cases:
- Functions that result in a system reboot, such as panic,
machine_real_restart and rust_begin_unwind
- Functions that are never executed by tasks, such as rest_init and
cpu_startup_entry
- Functions implemented in assembly, such as rewind_stack_and_make_dead and
xen_cpu_bringup_again, lack an associated BTF ID.
With this change, attaching fexit probes to functions like do_exit() will
be rejected.
$ ./fexit
libbpf: prog 'fexit': BPF program load failed: -EINVAL
libbpf: prog 'fexit': -- BEGIN PROG LOAD LOG --
Attaching fexit/fmod_ret to __noreturn functions is rejected.
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20250318114447.75484-2-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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storage
[ Upstream commit f4edc66e48a694b3e6d164cc71f059de542dfaec ]
The current cgrp storage has a percpu counter, bpf_cgrp_storage_busy,
to detect potential deadlock at a spin_lock that the local storage
acquires during new storage creation.
There are false positives. It turns out to be too noisy in
production. For example, a bpf prog may be doing a
bpf_cgrp_storage_get on map_a. An IRQ comes in and triggers
another bpf_cgrp_storage_get on a different map_b. It will then
trigger the false positive deadlock check in the percpu counter.
On top of that, both are doing lookup only and no need to create
new storage, so practically it does not need to acquire
the spin_lock.
The bpf_task_storage_get already has a strategy to minimize this
false positive by only failing if the bpf_task_storage_get needs
to create a new storage and the percpu counter is busy. Creating
a new storage is the only time it must acquire the spin_lock.
This patch borrows the same idea. Unlike task storage that
has a separate variant for tracing (_recur) and non-tracing, this
patch stays with one bpf_cgrp_storage_get helper to keep it simple
for now in light of the upcoming res_spin_lock.
The variable could potentially use a better name noTbusy instead
of nobusy. This patch follows the same naming in
bpf_task_storage_get for now.
I have tested it by temporarily adding noinline to
the cgroup_storage_lookup(), traced it by fentry, and the fentry
program succeeded in calling bpf_cgrp_storage_get().
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20250318182759.3676094-1-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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commit 8b62645b09f870d70c7910e7550289d444239a46 upstream.
The function __bpf_ringbuf_reserve is invoked from a tracepoint, which
disables preemption. Using spinlock_t in this context can lead to a
"sleep in atomic" warning in the RT variant. This issue is illustrated
in the example below:
BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 556208, name: test_progs
preempt_count: 1, expected: 0
RCU nest depth: 1, expected: 1
INFO: lockdep is turned off.
Preemption disabled at:
[<ffffd33a5c88ea44>] migrate_enable+0xc0/0x39c
CPU: 7 PID: 556208 Comm: test_progs Tainted: G
Hardware name: Qualcomm SA8775P Ride (DT)
Call trace:
dump_backtrace+0xac/0x130
show_stack+0x1c/0x30
dump_stack_lvl+0xac/0xe8
dump_stack+0x18/0x30
__might_resched+0x3bc/0x4fc
rt_spin_lock+0x8c/0x1a4
__bpf_ringbuf_reserve+0xc4/0x254
bpf_ringbuf_reserve_dynptr+0x5c/0xdc
bpf_prog_ac3d15160d62622a_test_read_write+0x104/0x238
trace_call_bpf+0x238/0x774
perf_call_bpf_enter.isra.0+0x104/0x194
perf_syscall_enter+0x2f8/0x510
trace_sys_enter+0x39c/0x564
syscall_trace_enter+0x220/0x3c0
do_el0_svc+0x138/0x1dc
el0_svc+0x54/0x130
el0t_64_sync_handler+0x134/0x150
el0t_64_sync+0x17c/0x180
Switch the spinlock to raw_spinlock_t to avoid this error.
Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it")
Reported-by: Brian Grech <bgrech@redhat.com>
Signed-off-by: Wander Lairson Costa <wander.lairson@gmail.com>
Signed-off-by: Wander Lairson Costa <wander@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20240920190700.617253-1-wander@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jianqi Ren <jianqi.ren.cn@windriver.com>
Signed-off-by: He Zhe <zhe.he@windriver.com>
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[ Upstream commit 5644c6b50ffee0a56c1e01430a8c88e34decb120 ]
The generic_map_lookup_batch currently returns EINTR if it fails with
ENOENT and retries several times on bpf_map_copy_value. The next batch
would start from the same location, presuming it's a transient issue.
This is incorrect if a map can actually have "holes", i.e.
"get_next_key" can return a key that does not point to a valid value. At
least the array of maps type may contain such holes legitly. Right now
these holes show up, generic batch lookup cannot proceed any more. It
will always fail with EINTR errors.
Rather, do not retry in generic_map_lookup_batch. If it finds a non
existing element, skip to the next key. This simple solution comes with
a price that transient errors may not be recovered, and the iteration
might cycle back to the first key under parallel deletion. For example,
Hou Tao <houtao@huaweicloud.com> pointed out a following scenario:
For LPM trie map:
(1) ->map_get_next_key(map, prev_key, key) returns a valid key
(2) bpf_map_copy_value() return -ENOMENT
It means the key must be deleted concurrently.
(3) goto next_key
It swaps the prev_key and key
(4) ->map_get_next_key(map, prev_key, key) again
prev_key points to a non-existing key, for LPM trie it will treat just
like prev_key=NULL case, the returned key will be duplicated.
With the retry logic, the iteration can continue to the key next to the
deleted one. But if we directly skip to the next key, the iteration loop
would restart from the first key for the lpm_trie type.
However, not all races may be recovered. For example, if current key is
deleted after instead of before bpf_map_copy_value, or if the prev_key
also gets deleted, then the loop will still restart from the first key
for lpm_tire anyway. For generic lookup it might be better to stay
simple, i.e. just skip to the next key. To guarantee that the output
keys are not duplicated, it is better to implement map type specific
batch operations, which can properly lock the trie and synchronize with
concurrent mutators.
Fixes: cb4d03ab499d ("bpf: Add generic support for lookup batch op")
Closes: https://lore.kernel.org/bpf/Z6JXtA1M5jAZx8xD@debian.debian/
Signed-off-by: Yan Zhai <yan@cloudflare.com>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/85618439eea75930630685c467ccefeac0942e2b.1739171594.git.yan@cloudflare.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit c78f4afbd962f43a3989f45f3ca04300252b19b5 ]
The following commit
bc235cdb423a ("bpf: Prevent deadlock from recursive bpf_task_storage_[get|delete]")
first introduced deadlock prevention for fentry/fexit programs attaching
on bpf_task_storage helpers. That commit also employed the logic in map
free path in its v6 version.
Later bpf_cgrp_storage was first introduced in
c4bcfb38a95e ("bpf: Implement cgroup storage available to non-cgroup-attached bpf progs")
which faces the same issue as bpf_task_storage, instead of its busy
counter, NULL was passed to bpf_local_storage_map_free() which opened
a window to cause deadlock:
<TASK>
(acquiring local_storage->lock)
_raw_spin_lock_irqsave+0x3d/0x50
bpf_local_storage_update+0xd1/0x460
bpf_cgrp_storage_get+0x109/0x130
bpf_prog_a4d4a370ba857314_cgrp_ptr+0x139/0x170
? __bpf_prog_enter_recur+0x16/0x80
bpf_trampoline_6442485186+0x43/0xa4
cgroup_storage_ptr+0x9/0x20
(holding local_storage->lock)
bpf_selem_unlink_storage_nolock.constprop.0+0x135/0x160
bpf_selem_unlink_storage+0x6f/0x110
bpf_local_storage_map_free+0xa2/0x110
bpf_map_free_deferred+0x5b/0x90
process_one_work+0x17c/0x390
worker_thread+0x251/0x360
kthread+0xd2/0x100
ret_from_fork+0x34/0x50
ret_from_fork_asm+0x1a/0x30
</TASK>
Progs:
- A: SEC("fentry/cgroup_storage_ptr")
- cgid (BPF_MAP_TYPE_HASH)
Record the id of the cgroup the current task belonging
to in this hash map, using the address of the cgroup
as the map key.
- cgrpa (BPF_MAP_TYPE_CGRP_STORAGE)
If current task is a kworker, lookup the above hash
map using function parameter @owner as the key to get
its corresponding cgroup id which is then used to get
a trusted pointer to the cgroup through
bpf_cgroup_from_id(). This trusted pointer can then
be passed to bpf_cgrp_storage_get() to finally trigger
the deadlock issue.
- B: SEC("tp_btf/sys_enter")
- cgrpb (BPF_MAP_TYPE_CGRP_STORAGE)
The only purpose of this prog is to fill Prog A's
hash map by calling bpf_cgrp_storage_get() for as
many userspace tasks as possible.
Steps to reproduce:
- Run A;
- while (true) { Run B; Destroy B; }
Fix this issue by passing its busy counter to the free procedure so
it can be properly incremented before storage/smap locking.
Fixes: c4bcfb38a95e ("bpf: Implement cgroup storage available to non-cgroup-attached bpf progs")
Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20241221061018.37717-1-wuyun.abel@bytedance.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit bc27c52eea189e8f7492d40739b7746d67b65beb ]
We use map->freeze_mutex to prevent races between map_freeze() and
memory mapping BPF map contents with writable permissions. The way we
naively do this means we'll hold freeze_mutex for entire duration of all
the mm and VMA manipulations, which is completely unnecessary. This can
potentially also lead to deadlocks, as reported by syzbot in [0].
So, instead, hold freeze_mutex only during writeability checks, bump
(proactively) "write active" count for the map, unlock the mutex and
proceed with mmap logic. And only if something went wrong during mmap
logic, then undo that "write active" counter increment.
[0] https://lore.kernel.org/bpf/678dcbc9.050a0220.303755.0066.GAE@google.com/
Fixes: fc9702273e2e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY")
Reported-by: syzbot+4dc041c686b7c816a71e@syzkaller.appspotmail.com
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20250129012246.1515826-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 98671a0fd1f14e4a518ee06b19037c20014900eb ]
For all BPF maps we ensure that VM_MAYWRITE is cleared when
memory-mapping BPF map contents as initially read-only VMA. This is
because in some cases BPF verifier relies on the underlying data to not
be modified afterwards by user space, so once something is mapped
read-only, it shouldn't be re-mmap'ed as read-write.
As such, it's not necessary to check VM_MAYWRITE in bpf_map_mmap() and
map->ops->map_mmap() callbacks: VM_WRITE should be consistently set for
read-write mappings, and if VM_WRITE is not set, there is no way for
user space to upgrade read-only mapping to read-write one.
This patch cleans up this VM_WRITE vs VM_MAYWRITE handling within
bpf_map_mmap(), which is an entry point for any BPF map mmap()-ing
logic. We also drop unnecessary sanitization of VM_MAYWRITE in BPF
ringbuf's map_mmap() callback implementation, as it is already performed
by common code in bpf_map_mmap().
Note, though, that in bpf_map_mmap_{open,close}() callbacks we can't
drop VM_MAYWRITE use, because it's possible (and is outside of
subsystem's control) to have initially read-write memory mapping, which
is subsequently dropped to read-only by user space through mprotect().
In such case, from BPF verifier POV it's read-write data throughout the
lifetime of BPF map, and is counted as "active writer".
But its VMAs will start out as VM_WRITE|VM_MAYWRITE, then mprotect() can
change it to just VM_MAYWRITE (and no VM_WRITE), so when its finally
munmap()'ed and bpf_map_mmap_close() is called, vm_flags will be just
VM_MAYWRITE, but we still need to decrement active writer count with
bpf_map_write_active_dec() as it's still considered to be a read-write
mapping by the rest of BPF subsystem.
Similar reasoning applies to bpf_map_mmap_open(), which is called
whenever mmap(), munmap(), and/or mprotect() forces mm subsystem to
split original VMA into multiple discontiguous VMAs.
Memory-mapping handling is a bit tricky, yes.
Cc: Jann Horn <jannh@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20250129012246.1515826-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: bc27c52eea18 ("bpf: avoid holding freeze_mutex during mmap operation")
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 8eef6ac4d70eb1f0099fff93321d90ce8fa49ee1 ]
In PREEMPT_RT, kmalloc(GFP_ATOMIC) is still not safe in non preemptible
context. bpf_mem_alloc must be used in PREEMPT_RT. This patch is
to enforce bpf_mem_alloc in the bpf_local_storage when CONFIG_PREEMPT_RT
is enabled.
[ 35.118559] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
[ 35.118566] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1832, name: test_progs
[ 35.118569] preempt_count: 1, expected: 0
[ 35.118571] RCU nest depth: 1, expected: 1
[ 35.118577] INFO: lockdep is turned off.
...
[ 35.118647] __might_resched+0x433/0x5b0
[ 35.118677] rt_spin_lock+0xc3/0x290
[ 35.118700] ___slab_alloc+0x72/0xc40
[ 35.118723] __kmalloc_noprof+0x13f/0x4e0
[ 35.118732] bpf_map_kzalloc+0xe5/0x220
[ 35.118740] bpf_selem_alloc+0x1d2/0x7b0
[ 35.118755] bpf_local_storage_update+0x2fa/0x8b0
[ 35.118784] bpf_sk_storage_get_tracing+0x15a/0x1d0
[ 35.118791] bpf_prog_9a118d86fca78ebb_trace_inet_sock_set_state+0x44/0x66
[ 35.118795] bpf_trace_run3+0x222/0x400
[ 35.118820] __bpf_trace_inet_sock_set_state+0x11/0x20
[ 35.118824] trace_inet_sock_set_state+0x112/0x130
[ 35.118830] inet_sk_state_store+0x41/0x90
[ 35.118836] tcp_set_state+0x3b3/0x640
There is no need to adjust the gfp_flags passing to the
bpf_mem_cache_alloc_flags() which only honors the GFP_KERNEL.
The verifier has ensured GFP_KERNEL is passed only in sleepable context.
It has been an old issue since the first introduction of the
bpf_local_storage ~5 years ago, so this patch targets the bpf-next.
bpf_mem_alloc is needed to solve it, so the Fixes tag is set
to the commit when bpf_mem_alloc was first used in the bpf_local_storage.
Fixes: 08a7ce384e33 ("bpf: Use bpf_mem_cache_alloc/free in bpf_local_storage_elem")
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20241218193000.2084281-1-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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tracking"
Revert commit ecc2aeeaa08a355d84d3ca9c3d2512399a194f29 which is commit
41f6f64e6999a837048b1bd13a2f8742964eca6b upstream.
Levi reported that commit ecc2aeeaa08a ("bpf: support non-r10 register
spill/fill to/from stack in precision tracking") cause eBPF program that
previously loads successfully in stable 6.6 now fails to load, when the
same program also loads successfully in v6.13-rc5.
Revert ecc2aeeaa08a until the problem has been probably figured out and
resolved.
Fixes: ecc2aeeaa08a ("bpf: support non-r10 register spill/fill to/from stack in precision tracking")
Reported-by: Levi Zim <rsworktech@outlook.com>
Link: https://lore.kernel.org/stable/MEYP282MB2312C3C8801476C4F262D6E1C6162@MEYP282MB2312.AUSP282.PROD.OUTLOOK.COM/
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit c4441ca86afe4814039ee1b32c39d833c1a16bbc ]
The bpf_remove_insns() function returns WARN_ON_ONCE(error), where
error is a result of bpf_adj_branches(), and thus should be always 0
However, if for any reason it is not 0, then it will be converted to
boolean by WARN_ON_ONCE and returned to user space as 1, not an actual
error value. Fix this by returning the original err after the WARN check.
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20241210114245.836164-1-aspsk@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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commit e9bd9c498cb0f5843996dbe5cbce7a1836a83c70 upstream.
Range propagation must not affect subreg_def marks, otherwise the
following example is rewritten by verifier incorrectly when
BPF_F_TEST_RND_HI32 flag is set:
0: call bpf_ktime_get_ns call bpf_ktime_get_ns
1: r0 &= 0x7fffffff after verifier r0 &= 0x7fffffff
2: w1 = w0 rewrites w1 = w0
3: if w0 < 10 goto +0 --------------> r11 = 0x2f5674a6 (r)
4: r1 >>= 32 r11 <<= 32 (r)
5: r0 = r1 r1 |= r11 (r)
6: exit; if w0 < 0xa goto pc+0
r1 >>= 32
r0 = r1
exit
(or zero extension of w1 at (2) is missing for architectures that
require zero extension for upper register half).
The following happens w/o this patch:
- r0 is marked as not a subreg at (0);
- w1 is marked as subreg at (2);
- w1 subreg_def is overridden at (3) by copy_register_state();
- w1 is read at (5) but mark_insn_zext() does not mark (2)
for zero extension, because w1 subreg_def is not set;
- because of BPF_F_TEST_RND_HI32 flag verifier inserts random
value for hi32 bits of (2) (marked (r));
- this random value is read at (5).
Fixes: 75748837b7e5 ("bpf: Propagate scalar ranges through register assignments.")
Reported-by: Lonial Con <kongln9170@gmail.com>
Signed-off-by: Lonial Con <kongln9170@gmail.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Closes: https://lore.kernel.org/bpf/7e2aa30a62d740db182c170fdd8f81c596df280d.camel@gmail.com
Link: https://lore.kernel.org/bpf/20240924210844.1758441-1-eddyz87@gmail.com
[ shung-hsi.yu: sync_linked_regs() was called find_equal_scalars() before commit
4bf79f9be434 ("bpf: Track equal scalars history on per-instruction level"), and
modification is done because there is only a single call to
copy_register_state() before commit 98d7ca374ba4 ("bpf: Track delta between
"linked" registers."). ]
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 659b9ba7cb2d7adb64618b87ddfaa528a143766e upstream.
Robert Morris reported the following program type which passes the
verifier in [0]:
SEC("struct_ops/bpf_cubic_init")
void BPF_PROG(bpf_cubic_init, struct sock *sk)
{
asm volatile("r2 = *(u16*)(r1 + 0)"); // verifier should demand u64
asm volatile("*(u32 *)(r2 +1504) = 0"); // 1280 in some configs
}
The second line may or may not work, but the first instruction shouldn't
pass, as it's a narrow load into the context structure of the struct ops
callback. The code falls back to btf_ctx_access to ensure correctness
and obtaining the types of pointers. Ensure that the size of the access
is correctly checked to be 8 bytes, otherwise the verifier thinks the
narrow load obtained a trusted BTF pointer and will permit loads/stores
as it sees fit.
Perform the check on size after we've verified that the load is for a
pointer field, as for scalar values narrow loads are fine. Access to
structs passed as arguments to a BPF program are also treated as
scalars, therefore no adjustment is needed in their case.
Existing verifier selftests are broken by this change, but because they
were incorrect. Verifier tests for d_path were performing narrow load
into context to obtain path pointer, had this program actually run it
would cause a crash. The same holds for verifier_btf_ctx_access tests.
[0]: https://lore.kernel.org/bpf/51338.1732985814@localhost
Fixes: 9e15db66136a ("bpf: Implement accurate raw_tp context access via BTF")
Reported-by: Robert Morris <rtm@mit.edu>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241212092050.3204165-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit f44ec8733a8469143fde1984b5e6931b2e2f6f3f ]
In general, BPF link's underlying BPF program should be considered to be
reachable through attach hook -> link -> prog chain, and, pessimistically,
we have to assume that as long as link's memory is not safe to free,
attach hook's code might hold a pointer to BPF program and use it.
As such, it's not (generally) correct to put link's program early before
waiting for RCU GPs to go through. More eager bpf_prog_put() that we
currently do is mostly correct due to BPF program's release code doing
similar RCU GP waiting, but as will be shown in the following patches,
BPF program can be non-sleepable (and, thus, reliant on only "classic"
RCU GP), while BPF link's attach hook can have sleepable semantics and
needs to be protected by RCU Tasks Trace, and for such cases BPF link
has to go through RCU Tasks Trace + "classic" RCU GPs before being
deallocated. And so, if we put BPF program early, we might free BPF
program before we free BPF link, leading to use-after-free situation.
So, this patch defers bpf_prog_put() until we are ready to perform
bpf_link's deallocation. At worst, this delays BPF program freeing by
one extra RCU GP, but that seems completely acceptable. Alternatively,
we'd need more elaborate ways to determine BPF hook, BPF link, and BPF
program lifetimes, and how they relate to each other, which seems like
an unnecessary complication.
Note, for most BPF links we still will perform eager bpf_prog_put() and
link dealloc, so for those BPF links there are no observable changes
whatsoever. Only BPF links that use deferred dealloc might notice
slightly delayed freeing of BPF programs.
Also, to reduce code and logic duplication, extract program put + link
dealloc logic into bpf_link_dealloc() helper.
Link: https://lore.kernel.org/20241101181754.782341-1-andrii@kernel.org
Tested-by: Jordan Rife <jrife@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit b9e9ed90b10c82a4e9d4d70a2890f06bfcdd3b78 ]
For htab of maps, when the map is removed from the htab, it may hold the
last reference of the map. bpf_map_fd_put_ptr() will invoke
bpf_map_free_id() to free the id of the removed map element. However,
bpf_map_fd_put_ptr() is invoked while holding a bucket lock
(raw_spin_lock_t), and bpf_map_free_id() attempts to acquire map_idr_lock
(spinlock_t), triggering the following lockdep warning:
=============================
[ BUG: Invalid wait context ]
6.11.0-rc4+ #49 Not tainted
-----------------------------
test_maps/4881 is trying to lock:
ffffffff84884578 (map_idr_lock){+...}-{3:3}, at: bpf_map_free_id.part.0+0x21/0x70
other info that might help us debug this:
context-{5:5}
2 locks held by test_maps/4881:
#0: ffffffff846caf60 (rcu_read_lock){....}-{1:3}, at: bpf_fd_htab_map_update_elem+0xf9/0x270
#1: ffff888149ced148 (&htab->lockdep_key#2){....}-{2:2}, at: htab_map_update_elem+0x178/0xa80
stack backtrace:
CPU: 0 UID: 0 PID: 4881 Comm: test_maps Not tainted 6.11.0-rc4+ #49
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), ...
Call Trace:
<TASK>
dump_stack_lvl+0x6e/0xb0
dump_stack+0x10/0x20
__lock_acquire+0x73e/0x36c0
lock_acquire+0x182/0x450
_raw_spin_lock_irqsave+0x43/0x70
bpf_map_free_id.part.0+0x21/0x70
bpf_map_put+0xcf/0x110
bpf_map_fd_put_ptr+0x9a/0xb0
free_htab_elem+0x69/0xe0
htab_map_update_elem+0x50f/0xa80
bpf_fd_htab_map_update_elem+0x131/0x270
htab_map_update_elem+0x50f/0xa80
bpf_fd_htab_map_update_elem+0x131/0x270
bpf_map_update_value+0x266/0x380
__sys_bpf+0x21bb/0x36b0
__x64_sys_bpf+0x45/0x60
x64_sys_call+0x1b2a/0x20d0
do_syscall_64+0x5d/0x100
entry_SYSCALL_64_after_hwframe+0x76/0x7e
One way to fix the lockdep warning is using raw_spinlock_t for
map_idr_lock as well. However, bpf_map_alloc_id() invokes
idr_alloc_cyclic() after acquiring map_idr_lock, it will trigger a
similar lockdep warning because the slab's lock (s->cpu_slab->lock) is
still a spinlock.
Instead of changing map_idr_lock's type, fix the issue by invoking
htab_put_fd_value() after htab_unlock_bucket(). However, only deferring
the invocation of htab_put_fd_value() is not enough, because the old map
pointers in htab of maps can not be saved during batched deletion.
Therefore, also defer the invocation of free_htab_elem(), so these
to-be-freed elements could be linked together similar to lru map.
There are four callers for ->map_fd_put_ptr:
(1) alloc_htab_elem() (through htab_put_fd_value())
It invokes ->map_fd_put_ptr() under a raw_spinlock_t. The invocation of
htab_put_fd_value() can not simply move after htab_unlock_bucket(),
because the old element has already been stashed in htab->extra_elems.
It may be reused immediately after htab_unlock_bucket() and the
invocation of htab_put_fd_value() after htab_unlock_bucket() may release
the newly-added element incorrectly. Therefore, saving the map pointer
of the old element for htab of maps before unlocking the bucket and
releasing the map_ptr after unlock. Beside the map pointer in the old
element, should do the same thing for the special fields in the old
element as well.
(2) free_htab_elem() (through htab_put_fd_value())
Its caller includes __htab_map_lookup_and_delete_elem(),
htab_map_delete_elem() and __htab_map_lookup_and_delete_batch().
For htab_map_delete_elem(), simply invoke free_htab_elem() after
htab_unlock_bucket(). For __htab_map_lookup_and_delete_batch(), just
like lru map, linking the to-be-freed element into node_to_free list
and invoking free_htab_elem() for these element after unlock. It is safe
to reuse batch_flink as the link for node_to_free, because these
elements have been removed from the hash llist.
Because htab of maps doesn't support lookup_and_delete operation,
__htab_map_lookup_and_delete_elem() doesn't have the problem, so kept
it as is.
(3) fd_htab_map_free()
It invokes ->map_fd_put_ptr without raw_spinlock_t.
(4) bpf_fd_htab_map_update_elem()
It invokes ->map_fd_put_ptr without raw_spinlock_t.
After moving free_htab_elem() outside htab bucket lock scope, using
pcpu_freelist_push() instead of __pcpu_freelist_push() to disable
the irq before freeing elements, and protecting the invocations of
bpf_mem_cache_free() with migrate_{disable|enable} pair.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241106063542.357743-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
commit ab244dd7cf4c291f82faacdc50b45cc0f55b674d upstream.
Jordy reported issue against XSKMAP which also applies to DEVMAP - the
index used for accessing map entry, due to being a signed integer,
causes the OOB writes. Fix is simple as changing the type from int to
u32, however, when compared to XSKMAP case, one more thing needs to be
addressed.
When map is released from system via dev_map_free(), we iterate through
all of the entries and an iterator variable is also an int, which
implies OOB accesses. Again, change it to be u32.
Example splat below:
[ 160.724676] BUG: unable to handle page fault for address: ffffc8fc2c001000
[ 160.731662] #PF: supervisor read access in kernel mode
[ 160.736876] #PF: error_code(0x0000) - not-present page
[ 160.742095] PGD 0 P4D 0
[ 160.744678] Oops: Oops: 0000 [#1] PREEMPT SMP
[ 160.749106] CPU: 1 UID: 0 PID: 520 Comm: kworker/u145:12 Not tainted 6.12.0-rc1+ #487
[ 160.757050] Hardware name: Intel Corporation S2600WFT/S2600WFT, BIOS SE5C620.86B.02.01.0008.031920191559 03/19/2019
[ 160.767642] Workqueue: events_unbound bpf_map_free_deferred
[ 160.773308] RIP: 0010:dev_map_free+0x77/0x170
[ 160.777735] Code: 00 e8 fd 91 ed ff e8 b8 73 ed ff 41 83 7d 18 19 74 6e 41 8b 45 24 49 8b bd f8 00 00 00 31 db 85 c0 74 48 48 63 c3 48 8d 04 c7 <48> 8b 28 48 85 ed 74 30 48 8b 7d 18 48 85 ff 74 05 e8 b3 52 fa ff
[ 160.796777] RSP: 0018:ffffc9000ee1fe38 EFLAGS: 00010202
[ 160.802086] RAX: ffffc8fc2c001000 RBX: 0000000080000000 RCX: 0000000000000024
[ 160.809331] RDX: 0000000000000000 RSI: 0000000000000024 RDI: ffffc9002c001000
[ 160.816576] RBP: 0000000000000000 R08: 0000000000000023 R09: 0000000000000001
[ 160.823823] R10: 0000000000000001 R11: 00000000000ee6b2 R12: dead000000000122
[ 160.831066] R13: ffff88810c928e00 R14: ffff8881002df405 R15: 0000000000000000
[ 160.838310] FS: 0000000000000000(0000) GS:ffff8897e0c40000(0000) knlGS:0000000000000000
[ 160.846528] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 160.852357] CR2: ffffc8fc2c001000 CR3: 0000000005c32006 CR4: 00000000007726f0
[ 160.859604] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 160.866847] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 160.874092] PKRU: 55555554
[ 160.876847] Call Trace:
[ 160.879338] <TASK>
[ 160.881477] ? __die+0x20/0x60
[ 160.884586] ? page_fault_oops+0x15a/0x450
[ 160.888746] ? search_extable+0x22/0x30
[ 160.892647] ? search_bpf_extables+0x5f/0x80
[ 160.896988] ? exc_page_fault+0xa9/0x140
[ 160.900973] ? asm_exc_page_fault+0x22/0x30
[ 160.905232] ? dev_map_free+0x77/0x170
[ 160.909043] ? dev_map_free+0x58/0x170
[ 160.912857] bpf_map_free_deferred+0x51/0x90
[ 160.917196] process_one_work+0x142/0x370
[ 160.921272] worker_thread+0x29e/0x3b0
[ 160.925082] ? rescuer_thread+0x4b0/0x4b0
[ 160.929157] kthread+0xd4/0x110
[ 160.932355] ? kthread_park+0x80/0x80
[ 160.936079] ret_from_fork+0x2d/0x50
[ 160.943396] ? kthread_park+0x80/0x80
[ 160.950803] ret_from_fork_asm+0x11/0x20
[ 160.958482] </TASK>
Fixes: 546ac1ffb70d ("bpf: add devmap, a map for storing net device references")
CC: stable@vger.kernel.org
Reported-by: Jordy Zomer <jordyzomer@google.com>
Suggested-by: Jordy Zomer <jordyzomer@google.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/r/20241122121030.716788-3-maciej.fijalkowski@intel.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
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[ Upstream commit 27abc7b3fa2e09bbe41e2924d328121546865eda ]
trie_get_next_key() uses node->prefixlen == key->prefixlen to identify
an exact match, However, it is incorrect because when the target key
doesn't fully match the found node (e.g., node->prefixlen != matchlen),
these two nodes may also have the same prefixlen. It will return
expected result when the passed key exist in the trie. However when a
recently-deleted key or nonexistent key is passed to
trie_get_next_key(), it may skip keys and return incorrect result.
Fix it by using node->prefixlen == matchlen to identify exact matches.
When the condition is true after the search, it also implies
node->prefixlen equals key->prefixlen, otherwise, the search would
return NULL instead.
Fixes: b471f2f1de8b ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE map")
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241206110622.1161752-6-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
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[ Upstream commit 532d6b36b2bfac5514426a97a4df8d103d700d43 ]
When a LPM trie is full, in-place updates of existing elements
incorrectly return -ENOSPC.
Fix this by deferring the check of trie->n_entries. For new insertions,
n_entries must not exceed max_entries. However, in-place updates are
allowed even when the trie is full.
Fixes: b95a5c4db09b ("bpf: add a longest prefix match trie map implementation")
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241206110622.1161752-5-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
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[ Upstream commit 3d5611b4d7efbefb85a74fcdbc35c603847cc022 ]
There is no need to call kfree(im_node) when updating element fails,
because im_node must be NULL. Remove the unnecessary kfree() for
im_node.
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241206110622.1161752-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: 532d6b36b2bf ("bpf: Handle in-place update for full LPM trie correctly")
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit eae6a075e9537dd69891cf77ca5a88fa8a28b4a1 ]
Add the currently missing handling for the BPF_EXIST and BPF_NOEXIST
flags. These flags can be specified by users and are relevant since LPM
trie supports exact matches during update.
Fixes: b95a5c4db09b ("bpf: add a longest prefix match trie map implementation")
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241206110622.1161752-4-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
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[ Upstream commit b0e66977dc072906bb76555fb1a64261d7f63d0f ]
When CAP_PERFMON and CAP_SYS_ADMIN (allow_ptr_leaks) are disabled, the
verifier aims to reject partial overwrite on an 8-byte stack slot that
contains a spilled pointer.
However, in such a scenario, it rejects all partial stack overwrites as
long as the targeted stack slot is a spilled register, because it does
not check if the stack slot is a spilled pointer.
Incomplete checks will result in the rejection of valid programs, which
spill narrower scalar values onto scalar slots, as shown below.
0: R1=ctx() R10=fp0
; asm volatile ( @ repro.bpf.c:679
0: (7a) *(u64 *)(r10 -8) = 1 ; R10=fp0 fp-8_w=1
1: (62) *(u32 *)(r10 -8) = 1
attempt to corrupt spilled pointer on stack
processed 2 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0.
Fix this by expanding the check to not consider spilled scalar registers
when rejecting the write into the stack.
Previous discussion on this patch is at link [0].
[0]: https://lore.kernel.org/bpf/20240403202409.2615469-1-tao.lyu@epfl.ch
Fixes: ab125ed3ec1c ("bpf: fix check for attempt to corrupt spilled pointer")
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Tao Lyu <tao.lyu@epfl.ch>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241204044757.1483141-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 41f6f64e6999a837048b1bd13a2f8742964eca6b ]
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 <eddyz87@gmail.com>
Reported-by: Tao Lyu <tao.lyu@epfl.ch>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231205184248.1502704-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 8421d4c8762bd022cb491f2f0f7019ef51b4f0a7 ]
If a newly-added link type doesn't invoke BPF_LINK_TYPE(), accessing
bpf_link_type_strs[link->type] may result in an out-of-bounds access.
To spot such missed invocations early in the future, checking the
validity of link->type in bpf_link_show_fdinfo() and emitting a warning
when such invocations are missed.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241024013558.1135167-3-houtao@huaweicloud.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 434247637c66e1be2bc71a9987d4c3f0d8672387 ]
The kzmalloc call in bpf_check can fail when memory is very fragmented,
which in turn can lead to an OOM kill.
Use kvzmalloc to fall back to vmalloc when memory is too fragmented to
allocate an order 3 sized bpf verifier environment.
Admittedly this is not a very common case, and only happens on systems
where memory has already been squeezed close to the limit, but this does
not seem like much of a hot path, and it's a simple enough fix.
Signed-off-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Link: https://lore.kernel.org/r/20241008170735.16766766@imladris.surriel.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
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[ Upstream commit 117932eea99b729ee5d12783601a4f7f5fd58a23 ]
A hung_task problem shown below was found:
INFO: task kworker/0:0:8 blocked for more than 327 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Workqueue: events cgroup_bpf_release
Call Trace:
<TASK>
__schedule+0x5a2/0x2050
? find_held_lock+0x33/0x100
? wq_worker_sleeping+0x9e/0xe0
schedule+0x9f/0x180
schedule_preempt_disabled+0x25/0x50
__mutex_lock+0x512/0x740
? cgroup_bpf_release+0x1e/0x4d0
? cgroup_bpf_release+0xcf/0x4d0
? process_scheduled_works+0x161/0x8a0
? cgroup_bpf_release+0x1e/0x4d0
? mutex_lock_nested+0x2b/0x40
? __pfx_delay_tsc+0x10/0x10
mutex_lock_nested+0x2b/0x40
cgroup_bpf_release+0xcf/0x4d0
? process_scheduled_works+0x161/0x8a0
? trace_event_raw_event_workqueue_execute_start+0x64/0xd0
? process_scheduled_works+0x161/0x8a0
process_scheduled_works+0x23a/0x8a0
worker_thread+0x231/0x5b0
? __pfx_worker_thread+0x10/0x10
kthread+0x14d/0x1c0
? __pfx_kthread+0x10/0x10
ret_from_fork+0x59/0x70
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1b/0x30
</TASK>
This issue can be reproduced by the following pressuse test:
1. A large number of cpuset cgroups are deleted.
2. Set cpu on and off repeatly.
3. Set watchdog_thresh repeatly.
The scripts can be obtained at LINK mentioned above the signature.
The reason for this issue is cgroup_mutex and cpu_hotplug_lock are
acquired in different tasks, which may lead to deadlock.
It can lead to a deadlock through the following steps:
1. A large number of cpusets are deleted asynchronously, which puts a
large number of cgroup_bpf_release works into system_wq. The max_active
of system_wq is WQ_DFL_ACTIVE(256). Consequently, all active works are
cgroup_bpf_release works, and many cgroup_bpf_release works will be put
into inactive queue. As illustrated in the diagram, there are 256 (in
the acvtive queue) + n (in the inactive queue) works.
2. Setting watchdog_thresh will hold cpu_hotplug_lock.read and put
smp_call_on_cpu work into system_wq. However step 1 has already filled
system_wq, 'sscs.work' is put into inactive queue. 'sscs.work' has
to wait until the works that were put into the inacvtive queue earlier
have executed (n cgroup_bpf_release), so it will be blocked for a while.
3. Cpu offline requires cpu_hotplug_lock.write, which is blocked by step 2.
4. Cpusets that were deleted at step 1 put cgroup_release works into
cgroup_destroy_wq. They are competing to get cgroup_mutex all the time.
When cgroup_metux is acqured by work at css_killed_work_fn, it will
call cpuset_css_offline, which needs to acqure cpu_hotplug_lock.read.
However, cpuset_css_offline will be blocked for step 3.
5. At this moment, there are 256 works in active queue that are
cgroup_bpf_release, they are attempting to acquire cgroup_mutex, and as
a result, all of them are blocked. Consequently, sscs.work can not be
executed. Ultimately, this situation leads to four processes being
blocked, forming a deadlock.
system_wq(step1) WatchDog(step2) cpu offline(step3) cgroup_destroy_wq(step4)
...
2000+ cgroups deleted asyn
256 actives + n inactives
__lockup_detector_reconfigure
P(cpu_hotplug_lock.read)
put sscs.work into system_wq
256 + n + 1(sscs.work)
sscs.work wait to be executed
warting sscs.work finish
percpu_down_write
P(cpu_hotplug_lock.write)
...blocking...
css_killed_work_fn
P(cgroup_mutex)
cpuset_css_offline
P(cpu_hotplug_lock.read)
...blocking...
256 cgroup_bpf_release
mutex_lock(&cgroup_mutex);
..blocking...
To fix the problem, place cgroup_bpf_release works on a dedicated
workqueue which can break the loop and solve the problem. System wqs are
for misc things which shouldn't create a large number of concurrent work
items. If something is going to generate >WQ_DFL_ACTIVE(256) concurrent
work items, it should use its own dedicated workqueue.
Fixes: 4bfc0bb2c60e ("bpf: decouple the lifetime of cgroup_bpf from cgroup itself")
Cc: stable@vger.kernel.org # v5.3+
Link: https://lore.kernel.org/cgroups/e90c32d2-2a85-4f28-9154-09c7d320cb60@huawei.com/T/#t
Tested-by: Vishal Chourasia <vishalc@linux.ibm.com>
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 13400ac8fb80c57c2bfb12ebd35ee121ce9b4d21 ]
trie_get_next_key() allocates a node stack with size trie->max_prefixlen,
while it writes (trie->max_prefixlen + 1) nodes to the stack when it has
full paths from the root to leaves. For example, consider a trie with
max_prefixlen is 8, and the nodes with key 0x00/0, 0x00/1, 0x00/2, ...
0x00/8 inserted. Subsequent calls to trie_get_next_key with _key with
.prefixlen = 8 make 9 nodes be written on the node stack with size 8.
Fixes: b471f2f1de8b ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE map")
Signed-off-by: Byeonguk Jeong <jungbu2855@gmail.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@kernel.org>
Tested-by: Hou Tao <houtao1@huawei.com>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/Zxx384ZfdlFYnz6J@localhost.localdomain
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit aa30eb3260b2dea3a68d3c42a39f9a09c5e99cee ]
A specifically crafted program might trick verifier into growing very
long jump history within a single bpf_verifier_state instance.
Very long jump history makes mark_chain_precision() unreasonably slow,
especially in case if verifier processes a loop.
Mitigate this by forcing new state in is_state_visited() in case if
current state's jump history is too long.
Use same constant as in `skip_inf_loop_check`, but multiply it by
arbitrarily chosen value 2 to account for jump history containing not
only information about jumps, but also information about stack access.
For an example of problematic program consider the code below,
w/o this patch the example is processed by verifier for ~15 minutes,
before failing to allocate big-enough chunk for jmp_history.
0: r7 = *(u16 *)(r1 +0);"
1: r7 += 0x1ab064b9;"
2: if r7 & 0x702000 goto 1b;
3: r7 &= 0x1ee60e;"
4: r7 += r1;"
5: if r7 s> 0x37d2 goto +0;"
6: r0 = 0;"
7: exit;"
Perf profiling shows that most of the time is spent in
mark_chain_precision() ~95%.
The easiest way to explain why this program causes problems is to
apply the following patch:
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 0c216e71cec7..4b4823961abe 100644
\--- a/include/linux/bpf.h
\+++ b/include/linux/bpf.h
\@@ -1926,7 +1926,7 @@ struct bpf_array {
};
};
-#define BPF_COMPLEXITY_LIMIT_INSNS 1000000 /* yes. 1M insns */
+#define BPF_COMPLEXITY_LIMIT_INSNS 256 /* yes. 1M insns */
#define MAX_TAIL_CALL_CNT 33
/* Maximum number of loops for bpf_loop and bpf_iter_num.
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index f514247ba8ba..75e88be3bb3e 100644
\--- a/kernel/bpf/verifier.c
\+++ b/kernel/bpf/verifier.c
\@@ -18024,8 +18024,13 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
skip_inf_loop_check:
if (!force_new_state &&
env->jmps_processed - env->prev_jmps_processed < 20 &&
- env->insn_processed - env->prev_insn_processed < 100)
+ env->insn_processed - env->prev_insn_processed < 100) {
+ verbose(env, "is_state_visited: suppressing checkpoint at %d, %d jmps processed, cur->jmp_history_cnt is %d\n",
+ env->insn_idx,
+ env->jmps_processed - env->prev_jmps_processed,
+ cur->jmp_history_cnt);
add_new_state = false;
+ }
goto miss;
}
/* If sl->state is a part of a loop and this loop's entry is a part of
\@@ -18142,6 +18147,9 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
if (!add_new_state)
return 0;
+ verbose(env, "is_state_visited: new checkpoint at %d, resetting env->jmps_processed\n",
+ env->insn_idx);
+
/* There were no equivalent states, remember the current one.
* Technically the current state is not proven to be safe yet,
* but it will either reach outer most bpf_exit (which means it's safe)
And observe verification log:
...
is_state_visited: new checkpoint at 5, resetting env->jmps_processed
5: R1=ctx() R7=ctx(...)
5: (65) if r7 s> 0x37d2 goto pc+0 ; R7=ctx(...)
6: (b7) r0 = 0 ; R0_w=0
7: (95) exit
from 5 to 6: R1=ctx() R7=ctx(...) R10=fp0
6: R1=ctx() R7=ctx(...) R10=fp0
6: (b7) r0 = 0 ; R0_w=0
7: (95) exit
is_state_visited: suppressing checkpoint at 1, 3 jmps processed, cur->jmp_history_cnt is 74
from 2 to 1: R1=ctx() R7_w=scalar(...) R10=fp0
1: R1=ctx() R7_w=scalar(...) R10=fp0
1: (07) r7 += 447767737
is_state_visited: suppressing checkpoint at 2, 3 jmps processed, cur->jmp_history_cnt is 75
2: R7_w=scalar(...)
2: (45) if r7 & 0x702000 goto pc-2
... mark_precise 152 steps for r7 ...
2: R7_w=scalar(...)
is_state_visited: suppressing checkpoint at 1, 4 jmps processed, cur->jmp_history_cnt is 75
1: (07) r7 += 447767737
is_state_visited: suppressing checkpoint at 2, 4 jmps processed, cur->jmp_history_cnt is 76
2: R7_w=scalar(...)
2: (45) if r7 & 0x702000 goto pc-2
...
BPF program is too large. Processed 257 insn
The log output shows that checkpoint at label (1) is never created,
because it is suppressed by `skip_inf_loop_check` logic:
a. When 'if' at (2) is processed it pushes a state with insn_idx (1)
onto stack and proceeds to (3);
b. At (5) checkpoint is created, and this resets
env->{jmps,insns}_processed.
c. Verification proceeds and reaches `exit`;
d. State saved at step (a) is popped from stack and is_state_visited()
considers if checkpoint needs to be added, but because
env->{jmps,insns}_processed had been just reset at step (b)
the `skip_inf_loop_check` logic forces `add_new_state` to false.
e. Verifier proceeds with current state, which slowly accumulates
more and more entries in the jump history.
The accumulation of entries in the jump history is a problem because
of two factors:
- it eventually exhausts memory available for kmalloc() allocation;
- mark_chain_precision() traverses the jump history of a state,
meaning that if `r7` is marked precise, verifier would iterate
ever growing jump history until parent state boundary is reached.
(note: the log also shows a REG INVARIANTS VIOLATION warning
upon jset processing, but that's another bug to fix).
With this patch applied, the example above is rejected by verifier
under 1s of time, reaching 1M instructions limit.
The program is a simplified reproducer from syzbot report.
Previous discussion could be found at [1].
The patch does not cause any changes in verification performance,
when tested on selftests from veristat.cfg and cilium programs taken
from [2].
[1] https://lore.kernel.org/bpf/20241009021254.2805446-1-eddyz87@gmail.com/
[2] https://github.com/anakryiko/cilium
Changelog:
- v1 -> v2:
- moved patch to bpf tree;
- moved force_new_state variable initialization after declaration and
shortened the comment.
v1: https://lore.kernel.org/bpf/20241018020307.1766906-1-eddyz87@gmail.com/
Fixes: 2589726d12a1 ("bpf: introduce bounded loops")
Reported-by: syzbot+7e46cdef14bf496a3ab4@syzkaller.appspotmail.com
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20241029172641.1042523-1-eddyz87@gmail.com
Closes: https://lore.kernel.org/bpf/670429f6.050a0220.49194.0517.GAE@google.com/
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 8ea607330a39184f51737c6ae706db7fdca7628e ]
Lonial reported an issue in the BPF verifier where check_mem_size_reg()
has the following code:
if (!tnum_is_const(reg->var_off))
/* For unprivileged variable accesses, disable raw
* mode so that the program is required to
* initialize all the memory that the helper could
* just partially fill up.
*/
meta = NULL;
This means that writes are not checked when the register containing the
size of the passed buffer has not a fixed size. Through this bug, a BPF
program can write to a map which is marked as read-only, for example,
.rodata global maps.
The problem is that MEM_UNINIT's initial meaning that "the passed buffer
to the BPF helper does not need to be initialized" which was added back
in commit 435faee1aae9 ("bpf, verifier: add ARG_PTR_TO_RAW_STACK type")
got overloaded over time with "the passed buffer is being written to".
The problem however is that checks such as the above which were added later
via 06c1c049721a ("bpf: allow helpers access to variable memory") set meta
to NULL in order force the user to always initialize the passed buffer to
the helper. Due to the current double meaning of MEM_UNINIT, this bypasses
verifier write checks to the memory (not boundary checks though) and only
assumes the latter memory is read instead.
Fix this by reverting MEM_UNINIT back to its original meaning, and having
MEM_WRITE as an annotation to BPF helpers in order to then trigger the
BPF verifier checks for writing to memory.
Some notes: check_arg_pair_ok() ensures that for ARG_CONST_SIZE{,_OR_ZERO}
we can access fn->arg_type[arg - 1] since it must contain a preceding
ARG_PTR_TO_MEM. For check_mem_reg() the meta argument can be removed
altogether since we do check both BPF_READ and BPF_WRITE. Same for the
equivalent check_kfunc_mem_size_reg().
Fixes: 7b3552d3f9f6 ("bpf: Reject writes for PTR_TO_MAP_KEY in check_helper_mem_access")
Fixes: 97e6d7dab1ca ("bpf: Check PTR_TO_MEM | MEM_RDONLY in check_helper_mem_access")
Fixes: 15baa55ff5b0 ("bpf/verifier: allow all functions to read user provided context")
Reported-by: Lonial Con <kongln9170@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241021152809.33343-2-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 6fad274f06f038c29660aa53fbad14241c9fd976 ]
Add a MEM_WRITE attribute for BPF helper functions which can be used in
bpf_func_proto to annotate an argument type in order to let the verifier
know that the helper writes into the memory passed as an argument. In
the past MEM_UNINIT has been (ab)used for this function, but the latter
merely tells the verifier that the passed memory can be uninitialized.
There have been bugs with overloading the latter but aside from that
there are also cases where the passed memory is read + written which
currently cannot be expressed, see also 4b3786a6c539 ("bpf: Zero former
ARG_PTR_TO_{LONG,INT} args in case of error").
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241021152809.33343-1-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: 8ea607330a39 ("bpf: Fix overloading of MEM_UNINIT's meaning")
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 8a021e7fa10576eeb3938328f39bbf98fe7d4715 ]
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 <andreimatei1@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231221232225.568730-2-andreimatei1@gmail.com
Stable-dep-of: 8ea607330a39 ("bpf: Fix overloading of MEM_UNINIT's meaning")
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 9495a5b731fcaf580448a3438d63601c88367661 ]
In userspace, you can add a tid filter by setting
the "task.tid" field for "bpf_iter_link_info".
However, `get_pid_task` when called for the
`BPF_TASK_ITER_TID` type should have been using
`PIDTYPE_PID` (tid) instead of `PIDTYPE_TGID` (pid).
Fixes: f0d74c4da1f0 ("bpf: Parameterize task iterators.")
Signed-off-by: Jordan Rome <linux@jordanrome.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241016210048.1213935-1-linux@jordanrome.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit ae67b9fb8c4e981e929a665dcaa070f4b05ebdb4 ]
coerce_reg_to_size_sx() updates the register state after a sign-extension
operation. However, there's a bug in the assignment order of the unsigned
min/max values, leading to incorrect truncation:
0: (85) call bpf_get_prandom_u32#7 ; R0_w=scalar()
1: (57) r0 &= 1 ; R0_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=1,var_off=(0x0; 0x1))
2: (07) r0 += 254 ; R0_w=scalar(smin=umin=smin32=umin32=254,smax=umax=smax32=umax32=255,var_off=(0xfe; 0x1))
3: (bf) r0 = (s8)r0 ; R0_w=scalar(smin=smin32=-2,smax=smax32=-1,umin=umin32=0xfffffffe,umax=0xffffffff,var_off=(0xfffffffffffffffe; 0x1))
In the current implementation, the unsigned 32-bit min/max values
(u32_min_value and u32_max_value) are assigned directly from the 64-bit
signed min/max values (s64_min and s64_max):
reg->umin_value = reg->u32_min_value = s64_min;
reg->umax_value = reg->u32_max_value = s64_max;
Due to the chain assigmnent, this is equivalent to:
reg->u32_min_value = s64_min; // Unintended truncation
reg->umin_value = reg->u32_min_value;
reg->u32_max_value = s64_max; // Unintended truncation
reg->umax_value = reg->u32_max_value;
Fixes: 1f9a1ea821ff ("bpf: Support new sign-extension load insns")
Reported-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Reported-by: Zac Ecob <zacecob@protonmail.com>
Signed-off-by: Dimitar Kanaliev <dimitar.kanaliev@siteground.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Reviewed-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20241014121155.92887-2-dimitar.kanaliev@siteground.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 6cb86a0fdece87e126323ec1bb19deb16a52aedf ]
The verifier contains a cache for looking up module BTF objects when
calling kfuncs defined in modules. This cache uses a 'struct
bpf_kfunc_btf_tab', which contains a sorted list of BTF objects that
were already seen in the current verifier run, and the BTF objects are
looked up by the offset stored in the relocated call instruction using
bsearch().
The first time a given offset is seen, the module BTF is loaded from the
file descriptor passed in by libbpf, and stored into the cache. However,
there's a bug in the code storing the new entry: it stores a pointer to
the new cache entry, then calls sort() to keep the cache sorted for the
next lookup using bsearch(), and then returns the entry that was just
stored through the stored pointer. However, because sort() modifies the
list of entries in place *by value*, the stored pointer may no longer
point to the right entry, in which case the wrong BTF object will be
returned.
The end result of this is an intermittent bug where, if a BPF program
calls two functions with the same signature in two different modules,
the function from the wrong module may sometimes end up being called.
Whether this happens depends on the order of the calls in the BPF
program (as that affects whether sort() reorders the array of BTF
objects), making it especially hard to track down. Simon, credited as
reporter below, spent significant effort analysing and creating a
reproducer for this issue. The reproducer is added as a selftest in a
subsequent patch.
The fix is straight forward: simply don't use the stored pointer after
calling sort(). Since we already have an on-stack pointer to the BTF
object itself at the point where the function return, just use that, and
populate it from the cache entry in the branch where the lookup
succeeds.
Fixes: 2357672c54c3 ("bpf: Introduce BPF support for kernel module function calls")
Reported-by: Simon Sundberg <simon.sundberg@kau.se>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20241010-fix-kfunc-btf-caching-for-modules-v2-1-745af6c1af98@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 4deecdd29cf29844c7bd164d72dc38d2e672f64e ]
Previously when retrieving `bpf_link_info.perf_event` for
kprobe/uprobe/tracepoint, the `name_len` field was not populated by the
kernel, leaving it to reflect the value initially set by the user. This
behavior was inconsistent with how other input/output string buffer
fields function (e.g. `raw_tracepoint.tp_name_len`).
This patch fills `name_len` with the actual size of the string name.
Fixes: 1b715e1b0ec5 ("bpf: Support ->fill_link_info for perf_event")
Signed-off-by: Tyrone Wu <wudevelops@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20241008164312.46269-1-wudevelops@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit d5c16492c66fbfca85f36e42363d32212df5927b ]
At the moment we don't store cookie for perf_event probes,
while we do that for the rest of the probes.
Adding cookie fields to struct bpf_link_info perf event
probe records:
perf_event.uprobe
perf_event.kprobe
perf_event.tracepoint
perf_event.perf_event
And the code to store that in bpf_link_info struct.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20240119110505.400573-2-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: 4deecdd29cf2 ("bpf: fix unpopulated name_len field in perf_event link info")
Signed-off-by: Sasha Levin <sashal@kernel.org>
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