Adding support to get uprobe_link details through bpf_link_info
interface.
Adding new struct uprobe_multi to struct bpf_link_info to carry
the uprobe_multi link details.
The uprobe_multi.count is passed from user space to denote size
of array fields (offsets/ref_ctr_offsets/cookies). The actual
array size is stored back to uprobe_multi.count (allowing user
to find out the actual array size) and array fields are populated
up to the user passed size.
All the non-array fields (path/count/flags/pid) are always set.
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
include/uapi/linux/bpf.h | 10 +++++
kernel/trace/bpf_trace.c | 72 ++++++++++++++++++++++++++++++++++
tools/include/uapi/linux/bpf.h | 10 +++++
3 files changed, 92 insertions(+)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 7a5498242eaa..e88746ba7d21 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -6562,6 +6562,16 @@ struct bpf_link_info {
__u32 flags;
__u64 missed;
} kprobe_multi;
+ struct {
+ __aligned_u64 path;
+ __aligned_u64 offsets;
+ __aligned_u64 ref_ctr_offsets;
+ __aligned_u64 cookies;
+ __u32 path_size; /* in/out: real path size on success, including zero byte */
+ __u32 count; /* in/out: uprobe_multi offsets/ref_ctr_offsets/cookies count */
+ __u32 flags;
+ __u32 pid;
+ } uprobe_multi;
struct {
__u32 type; /* enum bpf_perf_event_type */
__u32 :32;
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index ad0323f27288..c284a4ad0315 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3042,6 +3042,7 @@ struct bpf_uprobe_multi_link {
struct path path;
struct bpf_link link;
u32 cnt;
+ u32 flags;
struct bpf_uprobe *uprobes;
struct task_struct *task;
};
@@ -3083,9 +3084,79 @@ static void bpf_uprobe_multi_link_dealloc(struct bpf_link *link)
kfree(umulti_link);
}
+static int bpf_uprobe_multi_link_fill_link_info(const struct bpf_link *link,
+ struct bpf_link_info *info)
+{
+ u64 __user *uref_ctr_offsets = u64_to_user_ptr(info->uprobe_multi.ref_ctr_offsets);
+ u64 __user *ucookies = u64_to_user_ptr(info->uprobe_multi.cookies);
+ u64 __user *uoffsets = u64_to_user_ptr(info->uprobe_multi.offsets);
+ u64 __user *upath = u64_to_user_ptr(info->uprobe_multi.path);
+ u32 upath_size = info->uprobe_multi.path_size;
+ struct bpf_uprobe_multi_link *umulti_link;
+ u32 ucount = info->uprobe_multi.count;
+ int err = 0, i;
+ long left;
+
+ if (!upath ^ !upath_size)
+ return -EINVAL;
+
+ if ((uoffsets || uref_ctr_offsets || ucookies) && !ucount)
+ return -EINVAL;
+
+ umulti_link = container_of(link, struct bpf_uprobe_multi_link, link);
+ info->uprobe_multi.count = umulti_link->cnt;
+ info->uprobe_multi.flags = umulti_link->flags;
+ 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);
+ kfree(buf);
+ if (left)
+ return -EFAULT;
+ info->uprobe_multi.path_size = upath_size;
+ }
+
+ if (!uoffsets && !ucookies && !uref_ctr_offsets)
+ return 0;
+
+ if (ucount < umulti_link->cnt)
+ err = -ENOSPC;
+ else
+ ucount = umulti_link->cnt;
+
+ for (i = 0; i < ucount; i++) {
+ if (uoffsets &&
+ put_user(umulti_link->uprobes[i].offset, uoffsets + i))
+ return -EFAULT;
+ if (uref_ctr_offsets &&
+ put_user(umulti_link->uprobes[i].ref_ctr_offset, uref_ctr_offsets + i))
+ return -EFAULT;
+ if (ucookies &&
+ put_user(umulti_link->uprobes[i].cookie, ucookies + i))
+ return -EFAULT;
+ }
+
+ return err;
+}
+
static const struct bpf_link_ops bpf_uprobe_multi_link_lops = {
.release = bpf_uprobe_multi_link_release,
.dealloc = bpf_uprobe_multi_link_dealloc,
+ .fill_link_info = bpf_uprobe_multi_link_fill_link_info,
};
static int uprobe_prog_run(struct bpf_uprobe *uprobe,
@@ -3274,6 +3345,7 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
link->uprobes = uprobes;
link->path = path;
link->task = task;
+ link->flags = flags;
bpf_link_init(&link->link, BPF_LINK_TYPE_UPROBE_MULTI,
&bpf_uprobe_multi_link_lops, prog);
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 7a5498242eaa..e88746ba7d21 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -6562,6 +6562,16 @@ struct bpf_link_info {
__u32 flags;
__u64 missed;
} kprobe_multi;
+ struct {
+ __aligned_u64 path;
+ __aligned_u64 offsets;
+ __aligned_u64 ref_ctr_offsets;
+ __aligned_u64 cookies;
+ __u32 path_size; /* in/out: real path size on success, including zero byte */
+ __u32 count; /* in/out: uprobe_multi offsets/ref_ctr_offsets/cookies count */
+ __u32 flags;
+ __u32 pid;
+ } uprobe_multi;
struct {
__u32 type; /* enum bpf_perf_event_type */
__u32 :32;
--
2.42.0
