]> git.ipfire.org Git - thirdparty/kernel/linux.git/commitdiff
bpf: Add log for attaching tracing programs to functions in deny list
authorKaFai Wan <kafai.wan@linux.dev>
Thu, 24 Jul 2025 15:14:52 +0000 (23:14 +0800)
committerAlexei Starovoitov <ast@kernel.org>
Tue, 29 Jul 2025 02:39:29 +0000 (19:39 -0700)
Show the rejected function name when attaching tracing programs to
functions in deny list.

With this change, we know why tracing programs can't attach to functions
like __rcu_read_lock() from log.

$ ./fentry
libbpf: prog '__rcu_read_lock': BPF program load failed: -EINVAL
libbpf: prog '__rcu_read_lock': -- BEGIN PROG LOAD LOG --
Attaching tracing programs to function '__rcu_read_lock' is rejected.

Suggested-by: Leon Hwang <leon.hwang@linux.dev>
Signed-off-by: KaFai Wan <kafai.wan@linux.dev>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20250724151454.499040-3-kafai.wan@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
kernel/bpf/verifier.c

index 4bf7392fd2c3af2f277e3feb1d0a40c26ce0550d..399f03e625086481316744e9fa58b9e7cf21703b 100644 (file)
@@ -23981,6 +23981,8 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
                        return ret;
        } else if (prog->type == BPF_PROG_TYPE_TRACING &&
                   btf_id_set_contains(&btf_id_deny, btf_id)) {
+               verbose(env, "Attaching tracing programs to function '%s' is rejected.\n",
+                       tgt_info.tgt_name);
                return -EINVAL;
        } else if ((prog->expected_attach_type == BPF_TRACE_FEXIT ||
                   prog->expected_attach_type == BPF_MODIFY_RETURN) &&