Previously when retrieving `bpf_link_info.uprobe_multi` with `path` and `path_size` fields unset, the `path_size` field is not populated (remains 0). This behavior was inconsistent with how other input/output string buffer fields work, as the field should be populated in cases when: - both buffer and length are set (currently works as expected) - both buffer and length are unset (not working as expected)
This patch now fills the `path_size` field when `path` and `path_size` are unset.
Fixes: e56fdbfb06e2 ("bpf: Add link_info support for uprobe multi link") Signed-off-by: Tyrone Wu wudevelops@gmail.com --- kernel/trace/bpf_trace.c | 35 +++++++++++++++++------------------ 1 file changed, 17 insertions(+), 18 deletions(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index a582cd25ca87..ba34e4f3fa8f 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -3133,7 +3133,8 @@ static int bpf_uprobe_multi_link_fill_link_info(const struct bpf_link *link, struct bpf_uprobe_multi_link *umulti_link; u32 ucount = info->uprobe_multi.count; int err = 0, i; - long left; + char *p, *buf; + long left = 0;
if (!upath ^ !upath_size) return -EINVAL; @@ -3147,26 +3148,24 @@ static int bpf_uprobe_multi_link_fill_link_info(const struct bpf_link *link, info->uprobe_multi.pid = umulti_link->task ? task_pid_nr_ns(umulti_link->task, task_active_pid_ns(current)) : 0;
- if (upath) { - char *p, *buf; - - upath_size = min_t(u32, upath_size, PATH_MAX); + upath_size = upath_size ? min_t(u32, upath_size, PATH_MAX) : PATH_MAX; + buf = kmalloc(upath_size, GFP_KERNEL); + if (!buf) + return -ENOMEM; + p = d_path(&umulti_link->path, buf, upath_size); + if (IS_ERR(p)) { + kfree(buf); + return PTR_ERR(p); + } + upath_size = buf + upath_size - p;
- buf = kmalloc(upath_size, GFP_KERNEL); - if (!buf) - return -ENOMEM; - p = d_path(&umulti_link->path, buf, upath_size); - if (IS_ERR(p)) { - kfree(buf); - return PTR_ERR(p); - } - upath_size = buf + upath_size - p; + if (upath) { left = copy_to_user(upath, p, upath_size); - kfree(buf); - if (left) - return -EFAULT; - info->uprobe_multi.path_size = upath_size; } + kfree(buf); + if (left) + return -EFAULT; + info->uprobe_multi.path_size = upath_size;
if (!uoffsets && !ucookies && !uref_ctr_offsets) return 0;
Add assertions in `bpf_link_info.uprobe_multi` test to verify that `count` and `path_size` fields are correctly populated when the fields are unset.
This tests a previous bug where the `path_size` field was not populated when `path` and `path_size` were unset.
Signed-off-by: Tyrone Wu wudevelops@gmail.com --- tools/testing/selftests/bpf/prog_tests/fill_link_info.c | 7 +++++++ 1 file changed, 7 insertions(+)
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..a38cf2a999fe 100644 --- a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c +++ b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c @@ -417,6 +417,13 @@ verify_umulti_link_info(int fd, bool retprobe, __u64 *offsets, if (!ASSERT_NEQ(err, -1, "readlink")) return -1;
+ memset(&info, 0, sizeof(info)); + err = bpf_link_get_info_by_fd(fd, &info, &len); + + ASSERT_EQ(info.uprobe_multi.count, 3, "info.uprobe_multi.count"); + ASSERT_EQ(info.uprobe_multi.path_size, strlen(path) + 1, + "info.uprobe_multi.path_size"); + for (bit = 0; bit < 8; bit++) { memset(&info, 0, sizeof(info)); info.uprobe_multi.path = ptr_to_u64(path_buf);
On Wed, Oct 9, 2024 at 3:07 PM Tyrone Wu wudevelops@gmail.com wrote:
Add assertions in `bpf_link_info.uprobe_multi` test to verify that `count` and `path_size` fields are correctly populated when the fields are unset.
This tests a previous bug where the `path_size` field was not populated when `path` and `path_size` were unset.
Signed-off-by: Tyrone Wu wudevelops@gmail.com
tools/testing/selftests/bpf/prog_tests/fill_link_info.c | 7 +++++++ 1 file changed, 7 insertions(+)
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..a38cf2a999fe 100644 --- a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c +++ b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c @@ -417,6 +417,13 @@ verify_umulti_link_info(int fd, bool retprobe, __u64 *offsets, if (!ASSERT_NEQ(err, -1, "readlink")) return -1;
memset(&info, 0, sizeof(info));err = bpf_link_get_info_by_fd(fd, &info, &len);
if (!ASSERT_OK(err, "link_get_info")) return -1;
?
Other than this, LGTM.
pw-bot: cr
ASSERT_EQ(info.uprobe_multi.count, 3, "info.uprobe_multi.count");ASSERT_EQ(info.uprobe_multi.path_size, strlen(path) + 1,"info.uprobe_multi.path_size");for (bit = 0; bit < 8; bit++) { memset(&info, 0, sizeof(info)); info.uprobe_multi.path = ptr_to_u64(path_buf);-- 2.43.0
Previously when retrieving `bpf_link_info.uprobe_multi` with `path` and `path_size` fields unset, the `path_size` field is not populated (remains 0). This behavior was inconsistent with how other input/output string buffer fields work, as the field should be populated in cases when: - both buffer and length are set (currently works as expected) - both buffer and length are unset (not working as expected)
This patch now fills the `path_size` field when `path` and `path_size` are unset.
Fixes: e56fdbfb06e2 ("bpf: Add link_info support for uprobe multi link") Signed-off-by: Tyrone Wu wudevelops@gmail.com --- V1 -> V2: no change
kernel/trace/bpf_trace.c | 36 +++++++++++++++++------------------- 1 file changed, 17 insertions(+), 19 deletions(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index a582cd25ca87..3bd402fa62a4 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -3133,7 +3133,8 @@ static int bpf_uprobe_multi_link_fill_link_info(const struct bpf_link *link, struct bpf_uprobe_multi_link *umulti_link; u32 ucount = info->uprobe_multi.count; int err = 0, i; - long left; + char *p, *buf; + long left = 0;
if (!upath ^ !upath_size) return -EINVAL; @@ -3147,26 +3148,23 @@ static int bpf_uprobe_multi_link_fill_link_info(const struct bpf_link *link, info->uprobe_multi.pid = umulti_link->task ? task_pid_nr_ns(umulti_link->task, task_active_pid_ns(current)) : 0;
- if (upath) { - char *p, *buf; - - upath_size = min_t(u32, upath_size, PATH_MAX); - - buf = kmalloc(upath_size, GFP_KERNEL); - if (!buf) - return -ENOMEM; - p = d_path(&umulti_link->path, buf, upath_size); - if (IS_ERR(p)) { - kfree(buf); - return PTR_ERR(p); - } - upath_size = buf + upath_size - p; - left = copy_to_user(upath, p, upath_size); + upath_size = upath_size ? min_t(u32, upath_size, PATH_MAX) : PATH_MAX; + buf = kmalloc(upath_size, GFP_KERNEL); + if (!buf) + return -ENOMEM; + p = d_path(&umulti_link->path, buf, upath_size); + if (IS_ERR(p)) { kfree(buf); - if (left) - return -EFAULT; - info->uprobe_multi.path_size = upath_size; + return PTR_ERR(p); } + upath_size = buf + upath_size - p; + + if (upath) + left = copy_to_user(upath, p, upath_size); + kfree(buf); + if (left) + return -EFAULT; + info->uprobe_multi.path_size = upath_size;
if (!uoffsets && !ucookies && !uref_ctr_offsets) return 0;
Add assertions in `bpf_link_info.uprobe_multi` test to verify that `count` and `path_size` fields are correctly populated when the fields are unset.
This tests a previous bug where the `path_size` field was not populated when `path` and `path_size` were unset.
Signed-off-by: Tyrone Wu wudevelops@gmail.com --- V1 -> V2: - Verify bpf_link_get_info_by_fd was successful before continuing with test
tools/testing/selftests/bpf/prog_tests/fill_link_info.c | 9 +++++++++ 1 file changed, 9 insertions(+)
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 745c5ada4c4b..d50cbd8040d4 100644 --- a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c +++ b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c @@ -420,6 +420,15 @@ verify_umulti_link_info(int fd, bool retprobe, __u64 *offsets, if (!ASSERT_NEQ(err, -1, "readlink")) return -1;
+ memset(&info, 0, sizeof(info)); + err = bpf_link_get_info_by_fd(fd, &info, &len); + if (!ASSERT_OK(err, "bpf_link_get_info_by_fd")) + return -1; + + ASSERT_EQ(info.uprobe_multi.count, 3, "info.uprobe_multi.count"); + ASSERT_EQ(info.uprobe_multi.path_size, strlen(path) + 1, + "info.uprobe_multi.path_size"); + for (bit = 0; bit < 8; bit++) { memset(&info, 0, sizeof(info)); info.uprobe_multi.path = ptr_to_u64(path_buf);
Hello:
This series was applied to bpf/bpf.git (master) by Andrii Nakryiko andrii@kernel.org:
On Fri, 11 Oct 2024 00:08:02 +0000 you wrote:
Previously when retrieving `bpf_link_info.uprobe_multi` with `path` and `path_size` fields unset, the `path_size` field is not populated (remains 0). This behavior was inconsistent with how other input/output string buffer fields work, as the field should be populated in cases when:
- both buffer and length are set (currently works as expected)
- both buffer and length are unset (not working as expected)
[...]
Here is the summary with links: - [bpf,v2,1/2] bpf: fix unpopulated path_size when uprobe_multi fields unset https://git.kernel.org/bpf/bpf/c/ad6b5b6ea9b7 - [bpf,v2,2/2] selftests/bpf: assert link info uprobe_multi count & path_size if unset https://git.kernel.org/bpf/bpf/c/b836cbdf3b81
You are awesome, thank you!
linux-kselftest-mirror@lists.linaro.org
-
Andrii Nakryiko -
patchwork-bot+netdevbpf＠kernel.org -
Tyrone Wu