diff options
| author | Alexei Starovoitov <ast@kernel.org> | 2018-12-03 22:46:05 -0800 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2018-12-04 17:22:02 +0100 |
| commit | 4f7b3e82589e0de723780198ec7983e427144c0a (patch) | |
| tree | 38fa3a5035551cfe6b4e5d7d5268ca4834e353f5 /tools | |
| parent | c3494801cd1785e2c25f1a5735fa19ddcf9665da (diff) | |
| download | linux-4f7b3e82589e0de723780198ec7983e427144c0a.tar.gz | |
bpf: improve verifier branch analysis
pathological bpf programs may try to force verifier to explode in
the number of branch states:
20: (d5) if r1 s<= 0x24000028 goto pc+0
21: (b5) if r0 <= 0xe1fa20 goto pc+2
22: (d5) if r1 s<= 0x7e goto pc+0
23: (b5) if r0 <= 0xe880e000 goto pc+0
24: (c5) if r0 s< 0x2100ecf4 goto pc+0
25: (d5) if r1 s<= 0xe880e000 goto pc+1
26: (c5) if r0 s< 0xf4041810 goto pc+0
27: (d5) if r1 s<= 0x1e007e goto pc+0
28: (b5) if r0 <= 0xe86be000 goto pc+0
29: (07) r0 += 16614
30: (c5) if r0 s< 0x6d0020da goto pc+0
31: (35) if r0 >= 0x2100ecf4 goto pc+0
Teach verifier to recognize always taken and always not taken branches.
This analysis is already done for == and != comparison.
Expand it to all other branches.
It also helps real bpf programs to be verified faster:
before after
bpf_lb-DLB_L3.o 2003 1940
bpf_lb-DLB_L4.o 3173 3089
bpf_lb-DUNKNOWN.o 1080 1065
bpf_lxc-DDROP_ALL.o 29584 28052
bpf_lxc-DUNKNOWN.o 36916 35487
bpf_netdev.o 11188 10864
bpf_overlay.o 6679 6643
bpf_lcx_jit.o 39555 38437
Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/testing/selftests/bpf/test_verifier.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index 5dd4410a716c..df6f751cc1e8 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -8576,7 +8576,7 @@ static struct bpf_test tests[] = { BPF_JMP_IMM(BPF_JA, 0, 0, -7), }, .fixup_map_hash_8b = { 4 }, - .errstr = "R0 invalid mem access 'inv'", + .errstr = "unbounded min value", .result = REJECT, }, { @@ -10547,7 +10547,7 @@ static struct bpf_test tests[] = { "check deducing bounds from const, 5", .insns = { BPF_MOV64_IMM(BPF_REG_0, 0), - BPF_JMP_IMM(BPF_JSGE, BPF_REG_0, 0, 1), + BPF_JMP_IMM(BPF_JSGE, BPF_REG_0, 1, 1), BPF_ALU64_REG(BPF_SUB, BPF_REG_0, BPF_REG_1), BPF_EXIT_INSN(), }, |