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bpf: Check netfilter ctx accesses are aligned

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Similarly to the previous patch fixing the flow_dissector ctx accesses,
nf_is_valid_access also doesn't check that ctx accesses are aligned.
Contrary to flow_dissector programs, netfilter programs don't have
context conversion. The unaligned ctx accesses are therefore allowed by
the verifier.

Fixes: fd9c663b9a ("bpf: minimal support for programs hooked into netfilter framework")
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/853ae9ed5edaa5196e8472ff0f1bb1cc24059214.1754039605.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Paul Chaignon
2025-08-01 11:48:15 +02:00
committed by Alexei Starovoitov
parent ead3d7b2b6
commit 9e6448f7b1
1 changed files with 3 additions and 0 deletions
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3
net/netfilter/nf_bpf_link.c
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@@ -296,6 +296,9 @@ static bool nf_is_valid_access(int off, int size, enum bpf_access_type type,
if (off < 0 || off >= sizeof(struct bpf_nf_ctx)) if (off < 0 || off >= sizeof(struct bpf_nf_ctx))
return false; return false;
if (off % size != 0)
return false;
if (type == BPF_WRITE) if (type == BPF_WRITE)
return false; return false;