From: Leon Hwang <leon.hwang@linux.dev>
To: bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
John Fastabend <john.fastabend@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
Jiri Olsa <jolsa@kernel.org>,
Emil Tsalapatis <emil@etsalapatis.com>,
Ihor Solodrai <ihor.solodrai@linux.dev>,
Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
KP Singh <kpsingh@kernel.org>,
Matt Bobrowski <matt@bobrowski.net>,
Shuah Khan <shuah@kernel.org>, Leon Hwang <leon.hwang@linux.dev>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
linux-kselftest@vger.kernel.org, netdev@vger.kernel.org
Subject: [PATCH bpf-next 1/9] bpf: Add log support for tracing link_create
Date: Mon, 9 Nov 2026 22:08:08 +0800 [thread overview]
Message-ID: <20261109140816.5196-2-leon.hwang@linux.dev> (raw)
In-Reply-To: <20261109140816.5196-1-leon.hwang@linux.dev>
Tracing BPF_LINK_CREATE returns an error without explaining why attachment
failed.
Pass the BPF_LINK_CREATE log to the tracing attach path and report invalid
attach parameters. Also pass it to bpf_check_attach_target() so freplace
attachment to a new target can report target-check failures.
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
---
kernel/bpf/syscall.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 9004f2673ccf..6147d386b777 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3674,7 +3674,8 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
int tgt_prog_fd,
u32 btf_id,
u64 bpf_cookie,
- enum bpf_attach_type attach_type)
+ enum bpf_attach_type attach_type,
+ struct bpf_verifier_log *log)
{
struct bpf_link_primer link_primer;
struct bpf_prog *tgt_prog = NULL;
@@ -3711,6 +3712,7 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
}
if (!!tgt_prog_fd != !!btf_id) {
+ bpf_log(log, "tgt_prog_fd and btf_id must be both set or both unset.\n");
err = -EINVAL;
goto out_put_prog;
}
@@ -3723,12 +3725,14 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
* attach_tracing_prog flag is set.
*/
if (prog->type != BPF_PROG_TYPE_EXT) {
+ bpf_log(log, "tgt_prog_fd is only allowed for freplace prog.\n");
err = -EINVAL;
goto out_put_prog;
}
tgt_prog = bpf_prog_get(tgt_prog_fd);
if (IS_ERR(tgt_prog)) {
+ bpf_log(log, "Invalid tgt_prog_fd.\n");
err = PTR_ERR(tgt_prog);
tgt_prog = NULL;
goto out_put_prog;
@@ -3783,11 +3787,13 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
*/
if (prog->type != BPF_PROG_TYPE_TRACING &&
prog->type != BPF_PROG_TYPE_LSM) {
+ bpf_log(log, "Only allow re-attach for tracing and lsm progs.\n");
err = -EINVAL;
goto out_unlock;
}
/* We can allow re-attach only if we have valid attach_btf. */
if (!prog->aux->attach_btf) {
+ bpf_log(log, "Invalid attach_btf.\n");
err = -EINVAL;
goto out_unlock;
}
@@ -3803,7 +3809,7 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
*/
struct bpf_attach_target_info tgt_info = {};
- err = bpf_check_attach_target(NULL, prog, tgt_prog, btf_id,
+ err = bpf_check_attach_target(log, prog, tgt_prog, btf_id,
&tgt_info);
if (err)
goto out_unlock;
@@ -3843,6 +3849,7 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
*/
if (prog->type == BPF_PROG_TYPE_EXT &&
prog->aux->kprobe_write_ctx != tgt_prog->aux->kprobe_write_ctx) {
+ bpf_log(log, "Invalid kprobe_write_ctx.\n");
err = -EINVAL;
goto out_unlock;
}
@@ -4374,7 +4381,7 @@ static int bpf_raw_tp_link_attach(struct bpf_prog *prog,
tp_name = prog->aux->attach_func_name;
break;
}
- return bpf_tracing_prog_attach(prog, 0, 0, 0, attach_type);
+ return bpf_tracing_prog_attach(prog, 0, 0, 0, attach_type, NULL);
case BPF_PROG_TYPE_RAW_TRACEPOINT:
case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
if (strncpy_from_user(buf, user_tp_name, sizeof(buf) - 1) < 0)
@@ -5907,11 +5914,13 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr, struct bpf_common_a
attr->link_create.target_fd,
attr->link_create.target_btf_id,
attr->link_create.tracing.cookie,
- attr->link_create.attach_type);
+ attr->link_create.attach_type,
+ log);
break;
case BPF_PROG_TYPE_LSM:
case BPF_PROG_TYPE_TRACING:
if (attr->link_create.attach_type != prog->expected_attach_type) {
+ bpf_log(log, "Invalid attach_type.\n");
ret = -EINVAL;
goto out;
}
@@ -5929,7 +5938,8 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr, struct bpf_common_a
attr->link_create.target_fd,
attr->link_create.target_btf_id,
attr->link_create.tracing.cookie,
- attr->link_create.attach_type);
+ attr->link_create.attach_type,
+ log);
break;
case BPF_PROG_TYPE_FLOW_DISSECTOR:
case BPF_PROG_TYPE_SK_LOOKUP:
--
2.55.0
next prev parent reply other threads:[~2026-11-09 14:08 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-09 14:08 [PATCH bpf-next 0/9] " Leon Hwang
2026-11-09 14:08 ` Leon Hwang [this message]
2026-11-09 14:47 ` [PATCH bpf-next 1/9] " bot+bpf-ci
2026-11-09 14:08 ` [PATCH bpf-next 2/9] bpf: Add log support for tracing_multi link_create Leon Hwang
2026-11-09 14:08 ` [PATCH bpf-next 3/9] bpf: Add log support for iter link_create Leon Hwang
2026-11-09 14:08 ` [PATCH bpf-next 4/9] bpf: Add log support for cgroup prog link_create Leon Hwang
2026-11-09 14:47 ` bot+bpf-ci
2026-11-09 14:08 ` [PATCH bpf-next 5/9] libbpf: Add log_opts support for BPF_TRACE_ITER Leon Hwang
2026-11-09 14:47 ` bot+bpf-ci
2026-11-09 14:08 ` [PATCH bpf-next 6/9] selftests/bpf: Verify tracing link_create logs Leon Hwang
2026-11-09 14:47 ` bot+bpf-ci
2026-11-09 14:08 ` [PATCH bpf-next 7/9] selftests/bpf: Verify tracing_multi " Leon Hwang
2026-11-09 14:08 ` [PATCH bpf-next 8/9] selftests/bpf: Verify iter " Leon Hwang
2026-11-09 14:08 ` [PATCH bpf-next 9/9] selftests/bpf: Verify cgroup prog " Leon Hwang
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