diff options
| author | Alexei Starovoitov <ast@kernel.org> | 2020-11-10 19:12:11 -0800 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2020-11-13 01:42:11 +0100 |
| commit | 6d94e741a8ff818e5518da8257f5ca0aaed1f269 (patch) | |
| tree | 8f456797a13698d3a57252a8d427a86ebaee1ff6 /include/linux/bpf_verifier.h | |
| parent | c36538798fc6c80bd8bdaddad803b0c86dc13d7c (diff) | |
bpf: Support for pointers beyond pkt_end.
This patch adds the verifier support to recognize inlined branch conditions.
The LLVM knows that the branch evaluates to the same value, but the verifier
couldn't track it. Hence causing valid programs to be rejected.
The potential LLVM workaround: https://reviews.llvm.org/D87428
can have undesired side effects, since LLVM doesn't know that
skb->data/data_end are being compared. LLVM has to introduce extra boolean
variable and use inline_asm trick to force easier for the verifier assembly.
Instead teach the verifier to recognize that
r1 = skb->data;
r1 += 10;
r2 = skb->data_end;
if (r1 > r2) {
here r1 points beyond packet_end and
subsequent
if (r1 > r2) // always evaluates to "true".
}
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20201111031213.25109-2-alexei.starovoitov@gmail.com
Diffstat (limited to 'include/linux/bpf_verifier.h')
| -rw-r--r-- | include/linux/bpf_verifier.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index e83ef6f6bf43..306869d4743b 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -45,7 +45,7 @@ struct bpf_reg_state { enum bpf_reg_type type; union { /* valid when type == PTR_TO_PACKET */ - u16 range; + int range; /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE | * PTR_TO_MAP_VALUE_OR_NULL |