github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-07-27 09:36:22 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

bpf: Add support to specify uprobe_multi target via file descriptor

Browse Source 
Allow uprobe_multi link to identify the target binary by an already
opened file descriptor.

Adding new BPF_F_UPROBE_MULTI_PATH_FD flag and the path_fd field for
the attr.link_create.uprobe_multi struct.

When the flag is set, we resolve the target from path_fd, without the
flag, we keep the existing string path behavior.

I don't see a use case for supporting O_PATH file descriptors, because
we need to read the binary first to get probes offsets, so I'm using
the CLASS(fd, f), which fails for O_PATH fds.

Assisted-by: Codex:GPT-5.4
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20260611114230.950379-4-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Jiri Olsa 2026-06-11 13:42:26 +02:00 committed by Alexei Starovoitov
parent 65d81609e9
commit 26330a9226
4 changed files with 51 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
include/uapi/linux/bpf.h
View File

@ -1327,7 +1327,11 @@ enum {
* BPF_TRACE_UPROBE_MULTI attach type to create return probe.
*/
enum {
BPF_F_UPROBE_MULTI_RETURN = (1U << 0)
/* Get return uprobe. */
BPF_F_UPROBE_MULTI_RETURN = (1U << 0),
/* Get path from provided path_fd. */
BPF_F_UPROBE_MULTI_PATH_FD = (1U << 1),
};
/* link_create.netfilter.flags used in LINK_CREATE command for
@ -1864,6 +1868,7 @@ union bpf_attr {
__u32 cnt;
__u32 flags;
__u32 pid;
__u32 path_fd;
} uprobe_multi;
struct {
union {

4
kernel/bpf/syscall.c
View File

@ -3480,7 +3480,7 @@ static void bpf_link_show_fdinfo(struct seq_file *m, struct file *filp)
seq_printf(m, "link_type:\t%s\n", link->flags == BPF_F_KPROBE_MULTI_RETURN ?
"kretprobe_multi" : "kprobe_multi");
else if (link->type == BPF_LINK_TYPE_UPROBE_MULTI)
seq_printf(m, "link_type:\t%s\n", link->flags == BPF_F_UPROBE_MULTI_RETURN ?
seq_printf(m, "link_type:\t%s\n", link->flags & BPF_F_UPROBE_MULTI_RETURN ?
"uretprobe_multi" : "uprobe_multi");
else
seq_printf(m, "link_type:\t%s\n", bpf_link_type_strs[type]);
@ -5840,7 +5840,7 @@ static int bpf_map_do_batch(const union bpf_attr *attr,
return err;
}
#define BPF_LINK_CREATE_LAST_FIELD link_create.uprobe_multi.pid
#define BPF_LINK_CREATE_LAST_FIELD link_create.uprobe_multi.path_fd
static int link_create(union bpf_attr *attr, bpfptr_t uattr)
{
struct bpf_prog *prog;

43
kernel/trace/bpf_trace.c
View File

@ -23,6 +23,7 @@
#include <linux/sort.h>
#include <linux/key.h>
#include <linux/namei.h>
#include <linux/file.h>
#include <net/bpf_sk_storage.h>
@ -3214,6 +3215,38 @@ static u64 bpf_uprobe_multi_cookie(struct bpf_run_ctx *ctx)
return run_ctx->uprobe->cookie;
}
static int bpf_uprobe_multi_get_path(const union bpf_attr *attr, struct path *path)
{
void __user *upath = u64_to_user_ptr(attr->link_create.uprobe_multi.path);
u32 path_fd = attr->link_create.uprobe_multi.path_fd;
u32 flags = attr->link_create.uprobe_multi.flags;
if (flags & BPF_F_UPROBE_MULTI_PATH_FD) {
/*
* When BPF_F_UPROBE_MULTI_PATH_FD is set, the executable is
* identified by path_fd, upath must be NULL.
*/
if (upath)
return -EINVAL;
CLASS(fd, f)(path_fd);
if (fd_empty(f))
return -EBADF;
*path = fd_file(f)->f_path;
path_get(path);
return 0;
}
/*
* When BPF_F_UPROBE_MULTI_PATH_FD is not set, the path is resolved
* relative to the cwd (AT_FDCWD) or absolute using the upath string.
*/
if (!upath || path_fd)
return -EINVAL;
return user_path_at(AT_FDCWD, upath, LOOKUP_FOLLOW, path);
}
int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
{
struct bpf_uprobe_multi_link *link = NULL;
@ -3223,7 +3256,6 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
struct task_struct *task = NULL;
unsigned long __user *uoffsets;
u64 __user *ucookies;
void __user *upath;
unsigned long size;
u32 flags, cnt, i;
struct path path;
@ -3241,19 +3273,18 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
return -EINVAL;
flags = attr->link_create.uprobe_multi.flags;
if (flags & ~BPF_F_UPROBE_MULTI_RETURN)
if (flags & ~(BPF_F_UPROBE_MULTI_RETURN | BPF_F_UPROBE_MULTI_PATH_FD))
return -EINVAL;
/*
* path, offsets and cnt are mandatory,
* offsets and cnt are mandatory,
* ref_ctr_offsets and cookies are optional
*/
upath = u64_to_user_ptr(attr->link_create.uprobe_multi.path);
uoffsets = u64_to_user_ptr(attr->link_create.uprobe_multi.offsets);
cnt = attr->link_create.uprobe_multi.cnt;
pid = attr->link_create.uprobe_multi.pid;
if (!upath || !uoffsets || !cnt || pid < 0)
if (!uoffsets || !cnt || pid < 0)
return -EINVAL;
if (cnt > MAX_UPROBE_MULTI_CNT)
return -E2BIG;
@ -3271,7 +3302,7 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
!access_ok(ucookies, size))
return -EFAULT;
err = user_path_at(AT_FDCWD, upath, LOOKUP_FOLLOW, &path);
err = bpf_uprobe_multi_get_path(attr, &path);
if (err)
return err;

7
tools/include/uapi/linux/bpf.h
View File

@ -1327,7 +1327,11 @@ enum {
* BPF_TRACE_UPROBE_MULTI attach type to create return probe.
*/
enum {
BPF_F_UPROBE_MULTI_RETURN = (1U << 0)
/* Get return uprobe. */
BPF_F_UPROBE_MULTI_RETURN = (1U << 0),
/* Get path from provided path_fd. */
BPF_F_UPROBE_MULTI_PATH_FD = (1U << 1),
};
/* link_create.netfilter.flags used in LINK_CREATE command for
@ -1864,6 +1868,7 @@ union bpf_attr {
__u32 cnt;
__u32 flags;
__u32 pid;
__u32 path_fd;
} uprobe_multi;
struct {
union {