bpf: Allow helpers access trusted PTR_TO_BTF_ID.

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The verifier rejects the code:
  bpf_strncmp(task->comm, 16, "my_task");
with the message:
  16: (85) call bpf_strncmp#182
  R1 type=trusted_ptr_ expected=fp, pkt, pkt_meta, map_key, map_value, mem, ringbuf_mem, buf

Teach the verifier that such access pattern is safe.
Do not allow untrusted and legacy ptr_to_btf_id to be passed into helpers.

Reported-by: David Vernet <void@manifault.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230313235845.61029-3-alexei.starovoitov@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

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Alexei Starovoitov 2023-03-13 16:58:44 -07:00 • committed by Martin KaFai Lau

parent c9267aa8b7

commit 3e30be4288

1 changed files with 15 additions and 0 deletions

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kernel/bpf/verifier.c

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