user/sven/linux.git/kernel/bpf, branch v4.14.299

bpf: Verifer, adjust_scalar_min_max_vals to always call update_reg_bounds()

2022-09-15T10:23:49Z

commit 294f2fc6da27620a506e6c050241655459ccd6bd upstream. Currently, for all op verification we call __red_deduce_bounds() and __red_bound_offset() but we only call __update_reg_bounds() in bitwise ops. However, we could benefit from calling __update_reg_bounds() in BPF_ADD, BPF_SUB, and BPF_MUL cases as well. For example, a register with state 'R1_w=invP0' when we subtract from it, w1 -= 2 Before coerce we will now have an smin_value=S64_MIN, smax_value=U64_MAX and unsigned bounds umin_value=0, umax_value=U64_MAX. These will then be clamped to S32_MIN, U32_MAX values by coerce in the case of alu32 op as done in above example. However tnum will be a constant because the ALU op is done on a constant. Without update_reg_bounds() we have a scenario where tnum is a const but our unsigned bounds do not reflect this. By calling update_reg_bounds after coerce to 32bit we further refine the umin_value to U64_MAX in the alu64 case or U32_MAX in the alu32 case above. Signed-off-by: John Fastabend Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/158507151689.15666.566796274289413203.stgit@john-Precision-5820-Tower Signed-off-by: Ovidiu Panait Signed-off-by: Greg Kroah-Hartman

bpf: Make sure mac_header was set before using it

2022-07-29T15:06:51Z

commit 0326195f523a549e0a9d7fd44c70b26fd7265090 upstream. Classic BPF has a way to load bytes starting from the mac header. Some skbs do not have a mac header, and skb_mac_header() in this case is returning a pointer that 65535 bytes after skb->head. Existing range check in bpf_internal_load_pointer_neg_helper() was properly kicking and no illegal access was happening. New sanity check in skb_mac_header() is firing, so we need to avoid it. WARNING: CPU: 1 PID: 28990 at include/linux/skbuff.h:2785 skb_mac_header include/linux/skbuff.h:2785 [inline] WARNING: CPU: 1 PID: 28990 at include/linux/skbuff.h:2785 bpf_internal_load_pointer_neg_helper+0x1b1/0x1c0 kernel/bpf/core.c:74 Modules linked in: CPU: 1 PID: 28990 Comm: syz-executor.0 Not tainted 5.19.0-rc4-syzkaller-00865-g4874fb9484be #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022 RIP: 0010:skb_mac_header include/linux/skbuff.h:2785 [inline] RIP: 0010:bpf_internal_load_pointer_neg_helper+0x1b1/0x1c0 kernel/bpf/core.c:74 Code: ff ff 45 31 f6 e9 5a ff ff ff e8 aa 27 40 00 e9 3b ff ff ff e8 90 27 40 00 e9 df fe ff ff e8 86 27 40 00 eb 9e e8 2f 2c f3 ff <0f> 0b eb b1 e8 96 27 40 00 e9 79 fe ff ff 90 41 57 41 56 41 55 41 RSP: 0018:ffffc9000309f668 EFLAGS: 00010216 RAX: 0000000000000118 RBX: ffffffffffeff00c RCX: ffffc9000e417000 RDX: 0000000000040000 RSI: ffffffff81873f21 RDI: 0000000000000003 RBP: ffff8880842878c0 R08: 0000000000000003 R09: 000000000000ffff R10: 000000000000ffff R11: 0000000000000001 R12: 0000000000000004 R13: ffff88803ac56c00 R14: 000000000000ffff R15: dffffc0000000000 FS: 00007f5c88a16700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fdaa9f6c058 CR3: 000000003a82c000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ____bpf_skb_load_helper_32 net/core/filter.c:276 [inline] bpf_skb_load_helper_32+0x191/0x220 net/core/filter.c:264 Fixes: f9aefd6b2aa3 ("net: warn if mac header was not set") Reported-by: syzbot Signed-off-by: Eric Dumazet Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220707123900.945305-1-edumazet@google.com Signed-off-by: Greg Kroah-Hartman

bpf: Add kconfig knob for disabling unpriv bpf by default

2022-02-16T11:44:50Z

commit 08389d888287c3823f80b0216766b71e17f0aba5 upstream. Add a kconfig knob which allows for unprivileged bpf to be disabled by default. If set, the knob sets /proc/sys/kernel/unprivileged_bpf_disabled to value of 2. This still allows a transition of 2 -> {0,1} through an admin. Similarly, this also still keeps 1 -> {1} behavior intact, so that once set to permanently disabled, it cannot be undone aside from a reboot. We've also added extra2 with max of 2 for the procfs handler, so that an admin still has a chance to toggle between 0 <-> 2. Either way, as an additional alternative, applications can make use of CAP_BPF that we added a while ago. Signed-off-by: Daniel Borkmann Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/74ec548079189e4e4dffaeb42b8987bb3c852eee.1620765074.git.daniel@iogearbox.net [fllinden@amazon.com: backported to 4.14] Signed-off-by: Frank van der Linden Signed-off-by: Greg Kroah-Hartman

bpf: fix truncated jump targets on heavy expansions

2022-02-08T17:16:27Z

commit 050fad7c4534c13c8eb1d9c2ba66012e014773cb upstream. Recently during testing, I ran into the following panic: [ 207.892422] Internal error: Accessing user space memory outside uaccess.h routines: 96000004 [#1] SMP [ 207.901637] Modules linked in: binfmt_misc [...] [ 207.966530] CPU: 45 PID: 2256 Comm: test_verifier Tainted: G W 4.17.0-rc3+ #7 [ 207.974956] Hardware name: FOXCONN R2-1221R-A4/C2U4N_MB, BIOS G31FB18A 03/31/2017 [ 207.982428] pstate: 60400005 (nZCv daif +PAN -UAO) [ 207.987214] pc : bpf_skb_load_helper_8_no_cache+0x34/0xc0 [ 207.992603] lr : 0xffff000000bdb754 [ 207.996080] sp : ffff000013703ca0 [ 207.999384] x29: ffff000013703ca0 x28: 0000000000000001 [ 208.004688] x27: 0000000000000001 x26: 0000000000000000 [ 208.009992] x25: ffff000013703ce0 x24: ffff800fb4afcb00 [ 208.015295] x23: ffff00007d2f5038 x22: ffff00007d2f5000 [ 208.020599] x21: fffffffffeff2a6f x20: 000000000000000a [ 208.025903] x19: ffff000009578000 x18: 0000000000000a03 [ 208.031206] x17: 0000000000000000 x16: 0000000000000000 [ 208.036510] x15: 0000ffff9de83000 x14: 0000000000000000 [ 208.041813] x13: 0000000000000000 x12: 0000000000000000 [ 208.047116] x11: 0000000000000001 x10: ffff0000089e7f18 [ 208.052419] x9 : fffffffffeff2a6f x8 : 0000000000000000 [ 208.057723] x7 : 000000000000000a x6 : 00280c6160000000 [ 208.063026] x5 : 0000000000000018 x4 : 0000000000007db6 [ 208.068329] x3 : 000000000008647a x2 : 19868179b1484500 [ 208.073632] x1 : 0000000000000000 x0 : ffff000009578c08 [ 208.078938] Process test_verifier (pid: 2256, stack limit = 0x0000000049ca7974) [ 208.086235] Call trace: [ 208.088672] bpf_skb_load_helper_8_no_cache+0x34/0xc0 [ 208.093713] 0xffff000000bdb754 [ 208.096845] bpf_test_run+0x78/0xf8 [ 208.100324] bpf_prog_test_run_skb+0x148/0x230 [ 208.104758] sys_bpf+0x314/0x1198 [ 208.108064] el0_svc_naked+0x30/0x34 [ 208.111632] Code: 91302260 f9400001 f9001fa1 d2800001 (29500680) [ 208.117717] ---[ end trace 263cb8a59b5bf29f ]--- The program itself which caused this had a long jump over the whole instruction sequence where all of the inner instructions required heavy expansions into multiple BPF instructions. Additionally, I also had BPF hardening enabled which requires once more rewrites of all constant values in order to blind them. Each time we rewrite insns, bpf_adj_branches() would need to potentially adjust branch targets which cross the patchlet boundary to accommodate for the additional delta. Eventually that lead to the case where the target offset could not fit into insn->off's upper 0x7fff limit anymore where then offset wraps around becoming negative (in s16 universe), or vice versa depending on the jump direction. Therefore it becomes necessary to detect and reject any such occasions in a generic way for native eBPF and cBPF to eBPF migrations. For the latter we can simply check bounds in the bpf_convert_filter()'s BPF_EMIT_JMP helper macro and bail out once we surpass limits. The bpf_patch_insn_single() for native eBPF (and cBPF to eBPF in case of subsequent hardening) is a bit more complex in that we need to detect such truncations before hitting the bpf_prog_realloc(). Thus the latter is split into an extra pass to probe problematic offsets on the original program in order to fail early. With that in place and carefully tested I no longer hit the panic and the rewrites are rejected properly. The above example panic I've seen on bpf-next, though the issue itself is generic in that a guard against this issue in bpf seems more appropriate in this case. Signed-off-by: Daniel Borkmann Acked-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov [ab: Dropped BPF_PSEUDO_CALL hardening, introoduced in 4.16] Signed-off-by: Alessio Balsini Acked-by: Thadeu Lima de Souza Cascardo Signed-off-by: Greg Kroah-Hartman

bpf: Fix the off-by-two error in range markings

2021-12-14T09:16:53Z

commit 2fa7d94afc1afbb4d702760c058dc2d7ed30f226 upstream. The first commit cited below attempts to fix the off-by-one error that appeared in some comparisons with an open range. Due to this error, arithmetically equivalent pieces of code could get different verdicts from the verifier, for example (pseudocode): // 1. Passes the verifier: if (data + 8 > data_end) return early read *(u64 *)data, i.e. [data; data+7] // 2. Rejected by the verifier (should still pass): if (data + 7 >= data_end) return early read *(u64 *)data, i.e. [data; data+7] The attempted fix, however, shifts the range by one in a wrong direction, so the bug not only remains, but also such piece of code starts failing in the verifier: // 3. Rejected by the verifier, but the check is stricter than in #1. if (data + 8 >= data_end) return early read *(u64 *)data, i.e. [data; data+7] The change performed by that fix converted an off-by-one bug into off-by-two. The second commit cited below added the BPF selftests written to ensure than code chunks like #3 are rejected, however, they should be accepted. This commit fixes the off-by-two error by adjusting new_range in the right direction and fixes the tests by changing the range into the one that should actually fail. Fixes: fb2a311a31d3 ("bpf: fix off by one for range markings with L{T, E} patterns") Fixes: b37242c773b2 ("bpf: add test cases to bpf selftests to cover all access tests") Signed-off-by: Maxim Mikityanskiy Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20211130181607.593149-1-maximmi@nvidia.com Signed-off-by: Greg Kroah-Hartman

bpf: Prevent increasing bpf_jit_limit above max

2021-11-26T10:40:22Z

[ Upstream commit fadb7ff1a6c2c565af56b4aacdd086b067eed440 ] Restrict bpf_jit_limit to the maximum supported by the arch's JIT. Signed-off-by: Lorenz Bauer Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20211014142554.53120-4-lmb@cloudflare.com Signed-off-by: Sasha Levin

bpf: Fix integer overflow in prealloc_elems_and_freelist()

2021-10-17T08:08:32Z

[ Upstream commit 30e29a9a2bc6a4888335a6ede968b75cd329657a ] In prealloc_elems_and_freelist(), the multiplication to calculate the size passed to bpf_map_area_alloc() could lead to an integer overflow. As a result, out-of-bounds write could occur in pcpu_freelist_populate() as reported by KASAN: [...] [ 16.968613] BUG: KASAN: slab-out-of-bounds in pcpu_freelist_populate+0xd9/0x100 [ 16.969408] Write of size 8 at addr ffff888104fc6ea0 by task crash/78 [ 16.970038] [ 16.970195] CPU: 0 PID: 78 Comm: crash Not tainted 5.15.0-rc2+ #1 [ 16.970878] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 [ 16.972026] Call Trace: [ 16.972306] dump_stack_lvl+0x34/0x44 [ 16.972687] print_address_description.constprop.0+0x21/0x140 [ 16.973297] ? pcpu_freelist_populate+0xd9/0x100 [ 16.973777] ? pcpu_freelist_populate+0xd9/0x100 [ 16.974257] kasan_report.cold+0x7f/0x11b [ 16.974681] ? pcpu_freelist_populate+0xd9/0x100 [ 16.975190] pcpu_freelist_populate+0xd9/0x100 [ 16.975669] stack_map_alloc+0x209/0x2a0 [ 16.976106] __sys_bpf+0xd83/0x2ce0 [...] The possibility of this overflow was originally discussed in [0], but was overlooked. Fix the integer overflow by changing elem_size to u64 from u32. [0] https://lore.kernel.org/bpf/728b238e-a481-eb50-98e9-b0f430ab01e7@gmail.com/ Fixes: 557c0c6e7df8 ("bpf: convert stackmap to pre-allocation") Signed-off-by: Tatsuhiko Yasumatsu Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20210930135545.173698-1-th.yasumatsu@gmail.com Signed-off-by: Sasha Levin

bpf: No need to simulate speculative domain for immediates

2021-06-10T10:43:53Z

commit a7036191277f9fa68d92f2071ddc38c09b1e5ee5 upstream. In 801c6058d14a ("bpf: Fix leakage of uninitialized bpf stack under speculation") we replaced masking logic with direct loads of immediates if the register is a known constant. Given in this case we do not apply any masking, there is also no reason for the operation to be truncated under the speculative domain. Therefore, there is also zero reason for the verifier to branch-off and simulate this case, it only needs to do it for unknown but bounded scalars. As a side-effect, this also enables few test cases that were previously rejected due to simulation under zero truncation. Signed-off-by: Daniel Borkmann Reviewed-by: Piotr Krysiuk Acked-by: Alexei Starovoitov Signed-off-by: Greg Kroah-Hartman

bpf: Fix mask direction swap upon off reg sign change

2021-06-10T10:43:53Z

commit bb01a1bba579b4b1c5566af24d95f1767859771e upstream. Masking direction as indicated via mask_to_left is considered to be calculated once and then used to derive pointer limits. Thus, this needs to be placed into bpf_sanitize_info instead so we can pass it to sanitize_ptr_alu() call after the pointer move. Piotr noticed a corner case where the off reg causes masking direction change which then results in an incorrect final aux->alu_limit. Fixes: 7fedb63a8307 ("bpf: Tighten speculative pointer arithmetic mask") Reported-by: Piotr Krysiuk Signed-off-by: Daniel Borkmann Reviewed-by: Piotr Krysiuk Acked-by: Alexei Starovoitov Signed-off-by: Greg Kroah-Hartman

bpf: Wrap aux data inside bpf_sanitize_info container

2021-06-10T10:43:53Z

commit 3d0220f6861d713213b015b582e9f21e5b28d2e0 upstream. Add a container structure struct bpf_sanitize_info which holds the current aux info, and update call-sites to sanitize_ptr_alu() to pass it in. This is needed for passing in additional state later on. Signed-off-by: Daniel Borkmann Reviewed-by: Piotr Krysiuk Acked-by: Alexei Starovoitov Signed-off-by: Greg Kroah-Hartman