1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
3*4882a593Smuzhiyun #include <linux/init.h>
4*4882a593Smuzhiyun #include <linux/module.h>
5*4882a593Smuzhiyun #include <linux/pid.h>
6*4882a593Smuzhiyun #include <linux/fs.h>
7*4882a593Smuzhiyun #include <linux/sched/signal.h>
8*4882a593Smuzhiyun #include "bpf_preload.h"
9*4882a593Smuzhiyun
10*4882a593Smuzhiyun extern char bpf_preload_umd_start;
11*4882a593Smuzhiyun extern char bpf_preload_umd_end;
12*4882a593Smuzhiyun
13*4882a593Smuzhiyun static int preload(struct bpf_preload_info *obj);
14*4882a593Smuzhiyun static int finish(void);
15*4882a593Smuzhiyun
16*4882a593Smuzhiyun static struct bpf_preload_ops umd_ops = {
17*4882a593Smuzhiyun .info.driver_name = "bpf_preload",
18*4882a593Smuzhiyun .preload = preload,
19*4882a593Smuzhiyun .finish = finish,
20*4882a593Smuzhiyun .owner = THIS_MODULE,
21*4882a593Smuzhiyun };
22*4882a593Smuzhiyun
preload(struct bpf_preload_info * obj)23*4882a593Smuzhiyun static int preload(struct bpf_preload_info *obj)
24*4882a593Smuzhiyun {
25*4882a593Smuzhiyun int magic = BPF_PRELOAD_START;
26*4882a593Smuzhiyun loff_t pos = 0;
27*4882a593Smuzhiyun int i, err;
28*4882a593Smuzhiyun ssize_t n;
29*4882a593Smuzhiyun
30*4882a593Smuzhiyun err = fork_usermode_driver(&umd_ops.info);
31*4882a593Smuzhiyun if (err)
32*4882a593Smuzhiyun return err;
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun /* send the start magic to let UMD proceed with loading BPF progs */
35*4882a593Smuzhiyun n = kernel_write(umd_ops.info.pipe_to_umh,
36*4882a593Smuzhiyun &magic, sizeof(magic), &pos);
37*4882a593Smuzhiyun if (n != sizeof(magic))
38*4882a593Smuzhiyun return -EPIPE;
39*4882a593Smuzhiyun
40*4882a593Smuzhiyun /* receive bpf_link IDs and names from UMD */
41*4882a593Smuzhiyun pos = 0;
42*4882a593Smuzhiyun for (i = 0; i < BPF_PRELOAD_LINKS; i++) {
43*4882a593Smuzhiyun n = kernel_read(umd_ops.info.pipe_from_umh,
44*4882a593Smuzhiyun &obj[i], sizeof(*obj), &pos);
45*4882a593Smuzhiyun if (n != sizeof(*obj))
46*4882a593Smuzhiyun return -EPIPE;
47*4882a593Smuzhiyun }
48*4882a593Smuzhiyun return 0;
49*4882a593Smuzhiyun }
50*4882a593Smuzhiyun
finish(void)51*4882a593Smuzhiyun static int finish(void)
52*4882a593Smuzhiyun {
53*4882a593Smuzhiyun int magic = BPF_PRELOAD_END;
54*4882a593Smuzhiyun struct pid *tgid;
55*4882a593Smuzhiyun loff_t pos = 0;
56*4882a593Smuzhiyun ssize_t n;
57*4882a593Smuzhiyun
58*4882a593Smuzhiyun /* send the last magic to UMD. It will do a normal exit. */
59*4882a593Smuzhiyun n = kernel_write(umd_ops.info.pipe_to_umh,
60*4882a593Smuzhiyun &magic, sizeof(magic), &pos);
61*4882a593Smuzhiyun if (n != sizeof(magic))
62*4882a593Smuzhiyun return -EPIPE;
63*4882a593Smuzhiyun
64*4882a593Smuzhiyun tgid = umd_ops.info.tgid;
65*4882a593Smuzhiyun if (tgid) {
66*4882a593Smuzhiyun wait_event(tgid->wait_pidfd, thread_group_exited(tgid));
67*4882a593Smuzhiyun umd_cleanup_helper(&umd_ops.info);
68*4882a593Smuzhiyun }
69*4882a593Smuzhiyun return 0;
70*4882a593Smuzhiyun }
71*4882a593Smuzhiyun
load_umd(void)72*4882a593Smuzhiyun static int __init load_umd(void)
73*4882a593Smuzhiyun {
74*4882a593Smuzhiyun int err;
75*4882a593Smuzhiyun
76*4882a593Smuzhiyun err = umd_load_blob(&umd_ops.info, &bpf_preload_umd_start,
77*4882a593Smuzhiyun &bpf_preload_umd_end - &bpf_preload_umd_start);
78*4882a593Smuzhiyun if (err)
79*4882a593Smuzhiyun return err;
80*4882a593Smuzhiyun bpf_preload_ops = &umd_ops;
81*4882a593Smuzhiyun return err;
82*4882a593Smuzhiyun }
83*4882a593Smuzhiyun
fini_umd(void)84*4882a593Smuzhiyun static void __exit fini_umd(void)
85*4882a593Smuzhiyun {
86*4882a593Smuzhiyun struct pid *tgid;
87*4882a593Smuzhiyun
88*4882a593Smuzhiyun bpf_preload_ops = NULL;
89*4882a593Smuzhiyun
90*4882a593Smuzhiyun /* kill UMD in case it's still there due to earlier error */
91*4882a593Smuzhiyun tgid = umd_ops.info.tgid;
92*4882a593Smuzhiyun if (tgid) {
93*4882a593Smuzhiyun kill_pid(tgid, SIGKILL, 1);
94*4882a593Smuzhiyun
95*4882a593Smuzhiyun wait_event(tgid->wait_pidfd, thread_group_exited(tgid));
96*4882a593Smuzhiyun umd_cleanup_helper(&umd_ops.info);
97*4882a593Smuzhiyun }
98*4882a593Smuzhiyun umd_unload_blob(&umd_ops.info);
99*4882a593Smuzhiyun }
100*4882a593Smuzhiyun late_initcall(load_umd);
101*4882a593Smuzhiyun module_exit(fini_umd);
102*4882a593Smuzhiyun MODULE_LICENSE("GPL");
103