diff options
| author | Juntong Deng <juntong.deng@outlook.com> | 2024-08-28 20:48:11 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2024-08-28 17:11:54 -0700 |
| commit | f633919d132cf1755d62278c989124c0ce23950f (patch) | |
| tree | b3b6c0ab0e1c140480f33b8d4218de072f6a06ab /kernel/bpf | |
| parent | c264487e5410e5a72db8a414566ab7d144223e6c (diff) | |
bpf: Relax KF_ACQUIRE kfuncs strict type matching constraint
Currently we cannot pass zero offset (implicit cast) or non-zero offset
pointers to KF_ACQUIRE kfuncs. This is because KF_ACQUIRE kfuncs
requires strict type matching, but zero offset or non-zero offset does
not change the type of pointer, which causes the ebpf program to be
rejected by the verifier.
This can cause some problems, one example is that bpf_skb_peek_tail
kfunc [0] cannot be implemented by just passing in non-zero offset
pointers. We cannot pass pointers like &sk->sk_write_queue (non-zero
offset) or &sk->__sk_common (zero offset) to KF_ACQUIRE kfuncs.
This patch makes KF_ACQUIRE kfuncs not require strict type matching.
[0]: https://lore.kernel.org/bpf/AM6PR03MB5848CA39CB4B7A4397D380B099B12@AM6PR03MB5848.eurprd03.prod.outlook.com/
Signed-off-by: Juntong Deng <juntong.deng@outlook.com>
Link: https://lore.kernel.org/r/AM6PR03MB5848FD2BD89BF0B6B5AA3B4C99952@AM6PR03MB5848.eurprd03.prod.outlook.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/verifier.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 33270b363689..f32e3b9bb4e5 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -11513,8 +11513,7 @@ static int process_kf_arg_ptr_to_btf_id(struct bpf_verifier_env *env, * btf_struct_ids_match() to walk the struct at the 0th offset, and * resolve types. */ - if (is_kfunc_acquire(meta) || - (is_kfunc_release(meta) && reg->ref_obj_id) || + if ((is_kfunc_release(meta) && reg->ref_obj_id) || btf_type_ids_nocast_alias(&env->log, reg_btf, reg_ref_id, meta->btf, ref_id)) strict_type_match = true; |