Commit e56fdbfb authored by Jiri Olsa's avatar Jiri Olsa Committed by Andrii Nakryiko
Browse files

bpf: Add link_info support for uprobe multi link 



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: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarYonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/bpf/20231125193130.834322-4-jolsa@kernel.org
parent 4930b7f5

include/uapi/linux/bpf.h

+10 −0
Original line number Diff line number Diff line
@@ -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;

kernel/trace/bpf_trace.c

+72 −0
Original line number Diff line number Diff line
@@ -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);

tools/include/uapi/linux/bpf.h

+10 −0
Original line number Diff line number Diff line
@@ -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;