From: tyrone-wu <wudevelops@gmail.com>
To: olsajiri@gmail.com, laoar.shao@gmail.com,
andrii.nakryiko@gmail.com, wudevelops@gmail.com,
bpf@vger.kernel.org
Cc: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com,
andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com,
song@kernel.org, yonghong.song@linux.dev, kpsingh@kernel.org,
sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org,
mykolal@fb.com, shuah@kernel.org, kernel-patches-bot@fb.com,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: [PATCH bpf] bpf: fix unpopulated name_len field in perf_event link info
Date: Mon, 30 Sep 2024 23:59:20 +0000 [thread overview]
Message-ID: <20240930235920.125417-1-wudevelops@gmail.com> (raw)
In-Reply-To: <ZvqLanKfaO9dLlf4@krava>
Previously when retrieving `bpf_link_info.perf_event` for
kprobe/uprobe/tracepoint, the `name_len` field was not populated by the
kernel, leaving it to reflect the value initially set by the user. This
behavior was inconsistent with how other input/output string buffer
fields function (e.g. `raw_tracepoint.tp_name_len`).
This patch fills `name_len` with the actual size of the string name. The
relevant selftests have also been updated to assert that `name_len`
contains the correct size rather than 0.
Link: https://lore.kernel.org/bpf/CABVU1kXwQXhqQGe0RTrr7eegtM6SVW_KayZBy16-yb0Snztmtg@mail.gmail.com/
Fixes: 1b715e1b0ec5 ("bpf: Support ->fill_link_info for perf_event")
Signed-off-by: tyrone-wu <wudevelops@gmail.com>
---
kernel/bpf/syscall.c | 25 +++++++++++++------
.../selftests/bpf/prog_tests/fill_link_info.c | 6 ++---
2 files changed, 20 insertions(+), 11 deletions(-)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index a8f1808a1ca5..90b6add4d0c9 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3565,7 +3565,7 @@ static void bpf_perf_link_dealloc(struct bpf_link *link)
}
static int bpf_perf_link_fill_common(const struct perf_event *event,
- char __user *uname, u32 ulen,
+ char __user *uname, u32 *ulen,
u64 *probe_offset, u64 *probe_addr,
u32 *fd_type, unsigned long *missed)
{
@@ -3574,18 +3574,20 @@ static int bpf_perf_link_fill_common(const struct perf_event *event,
size_t len;
int err;
- if (!ulen ^ !uname)
+ if (!(*ulen) ^ !uname)
return -EINVAL;
err = bpf_get_perf_event_info(event, &prog_id, fd_type, &buf,
probe_offset, probe_addr, missed);
if (err)
return err;
+
+ len = strlen(buf);
+ *ulen = len + 1;
if (!uname)
return 0;
if (buf) {
- len = strlen(buf);
- err = bpf_copy_to_user(uname, buf, ulen, len);
+ err = bpf_copy_to_user(uname, buf, *ulen, len);
if (err)
return err;
} else {
@@ -3609,7 +3611,7 @@ static int bpf_perf_link_fill_kprobe(const struct perf_event *event,
uname = u64_to_user_ptr(info->perf_event.kprobe.func_name);
ulen = info->perf_event.kprobe.name_len;
- err = bpf_perf_link_fill_common(event, uname, ulen, &offset, &addr,
+ err = bpf_perf_link_fill_common(event, uname, &ulen, &offset, &addr,
&type, &missed);
if (err)
return err;
@@ -3617,7 +3619,7 @@ static int bpf_perf_link_fill_kprobe(const struct perf_event *event,
info->perf_event.type = BPF_PERF_EVENT_KRETPROBE;
else
info->perf_event.type = BPF_PERF_EVENT_KPROBE;
-
+ info->perf_event.kprobe.name_len = ulen;
info->perf_event.kprobe.offset = offset;
info->perf_event.kprobe.missed = missed;
if (!kallsyms_show_value(current_cred()))
@@ -3639,7 +3641,7 @@ static int bpf_perf_link_fill_uprobe(const struct perf_event *event,
uname = u64_to_user_ptr(info->perf_event.uprobe.file_name);
ulen = info->perf_event.uprobe.name_len;
- err = bpf_perf_link_fill_common(event, uname, ulen, &offset, &addr,
+ err = bpf_perf_link_fill_common(event, uname, &ulen, &offset, &addr,
&type, NULL);
if (err)
return err;
@@ -3648,6 +3650,7 @@ static int bpf_perf_link_fill_uprobe(const struct perf_event *event,
info->perf_event.type = BPF_PERF_EVENT_URETPROBE;
else
info->perf_event.type = BPF_PERF_EVENT_UPROBE;
+ info->perf_event.uprobe.name_len = ulen;
info->perf_event.uprobe.offset = offset;
info->perf_event.uprobe.cookie = event->bpf_cookie;
return 0;
@@ -3673,12 +3676,18 @@ static int bpf_perf_link_fill_tracepoint(const struct perf_event *event,
{
char __user *uname;
u32 ulen;
+ int err;
uname = u64_to_user_ptr(info->perf_event.tracepoint.tp_name);
ulen = info->perf_event.tracepoint.name_len;
+ err = bpf_perf_link_fill_common(event, uname, &ulen, NULL, NULL, NULL, NULL);
+ if (err)
+ return err;
+
info->perf_event.type = BPF_PERF_EVENT_TRACEPOINT;
+ info->perf_event.tracepoint.name_len = ulen;
info->perf_event.tracepoint.cookie = event->bpf_cookie;
- return bpf_perf_link_fill_common(event, uname, ulen, NULL, NULL, NULL, NULL);
+ return 0;
}
static int bpf_perf_link_fill_perf_event(const struct perf_event *event,
diff --git a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
index f3932941bbaa..59077f260404 100644
--- a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
+++ b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
@@ -67,8 +67,8 @@ static int verify_perf_link_info(int fd, enum bpf_perf_event_type type, long add
ASSERT_EQ(info.perf_event.kprobe.cookie, PERF_EVENT_COOKIE, "kprobe_cookie");
+ ASSERT_EQ(info.perf_event.kprobe.name_len, strlen(KPROBE_FUNC) + 1, "name_len");
if (!info.perf_event.kprobe.func_name) {
- ASSERT_EQ(info.perf_event.kprobe.name_len, 0, "name_len");
info.perf_event.kprobe.func_name = ptr_to_u64(&buf);
info.perf_event.kprobe.name_len = sizeof(buf);
goto again;
@@ -79,8 +79,8 @@ static int verify_perf_link_info(int fd, enum bpf_perf_event_type type, long add
ASSERT_EQ(err, 0, "cmp_kprobe_func_name");
break;
case BPF_PERF_EVENT_TRACEPOINT:
+ ASSERT_EQ(info.perf_event.tracepoint.name_len, strlen(TP_NAME) + 1, "name_len");
if (!info.perf_event.tracepoint.tp_name) {
- ASSERT_EQ(info.perf_event.tracepoint.name_len, 0, "name_len");
info.perf_event.tracepoint.tp_name = ptr_to_u64(&buf);
info.perf_event.tracepoint.name_len = sizeof(buf);
goto again;
@@ -96,8 +96,8 @@ static int verify_perf_link_info(int fd, enum bpf_perf_event_type type, long add
case BPF_PERF_EVENT_URETPROBE:
ASSERT_EQ(info.perf_event.uprobe.offset, offset, "uprobe_offset");
+ ASSERT_EQ(info.perf_event.uprobe.name_len, strlen(UPROBE_FILE) + 1, "name_len");
if (!info.perf_event.uprobe.file_name) {
- ASSERT_EQ(info.perf_event.uprobe.name_len, 0, "name_len");
info.perf_event.uprobe.file_name = ptr_to_u64(&buf);
info.perf_event.uprobe.name_len = sizeof(buf);
goto again;
--
2.43.0
next parent reply other threads:[~2024-09-30 23:59 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <ZvqLanKfaO9dLlf4@krava>
2024-09-30 23:59 ` tyrone-wu [this message]
2024-10-02 11:37 ` [PATCH bpf] bpf: fix unpopulated name_len field in perf_event link info Jiri Olsa
2024-10-02 21:38 ` [PATCH bpf v2] " tyrone-wu
2024-10-03 19:10 ` Jiri Olsa
2024-10-03 20:23 ` [PATCH bpf v3] " tyrone-wu
2024-10-04 11:19 ` Jiri Olsa
2024-10-04 15:40 ` [PATCH bpf v4 1/2] " tyrone-wu
2024-10-04 15:40 ` [PATCH bpf v4 2/2] selftests/bpf: fix perf_event link info name_len assertion tyrone-wu
2024-10-06 6:00 ` [PATCH bpf v4 1/2] bpf: fix unpopulated name_len field in perf_event link info Yafang Shao
2024-10-06 19:51 ` [PATCH bpf v5 " tyrone-wu
2024-10-06 19:51 ` [PATCH bpf v5 2/2] selftests/bpf: fix perf_event link info name_len assertion tyrone-wu
2024-10-07 2:09 ` Yafang Shao
2024-10-07 2:09 ` [PATCH bpf v5 1/2] bpf: fix unpopulated name_len field in perf_event link info Yafang Shao
2024-10-07 8:07 ` Jiri Olsa
2024-10-07 18:29 ` [PATCH bpf v6 " Tyrone Wu
2024-10-07 18:29 ` [PATCH bpf v6 2/2] selftests/bpf: fix perf_event link info name_len assertion Tyrone Wu
2024-10-08 4:04 ` [PATCH bpf v6 1/2] bpf: fix unpopulated name_len field in perf_event link info Andrii Nakryiko
2024-10-08 16:43 ` [PATCH bpf v7 " Tyrone Wu
2024-10-08 16:43 ` [PATCH bpf v7 2/2] selftests/bpf: fix perf_event link info name_len assertion Tyrone Wu
2024-10-10 1:20 ` [PATCH bpf v7 1/2] bpf: fix unpopulated name_len field in perf_event link info patchwork-bot+netdevbpf
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