1// SPDX-License-Identifier: GPL-2.0
 2#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 3#include <linux/init.h>
 4#include <linux/module.h>
 5#include "bpf_preload.h"
 6#include "iterators/iterators.lskel.h"
 7
 8static struct bpf_link *maps_link, *progs_link;
 9static struct iterators_bpf *skel;
10
11static void free_links_and_skel(void)
12{
13	if (!IS_ERR_OR_NULL(maps_link))
14		bpf_link_put(maps_link);
15	if (!IS_ERR_OR_NULL(progs_link))
16		bpf_link_put(progs_link);
17	iterators_bpf__destroy(skel);
18}
19
20static int preload(struct bpf_preload_info *obj)
21{
22	strlcpy(obj[0].link_name, "maps.debug", sizeof(obj[0].link_name));
23	obj[0].link = maps_link;
24	strlcpy(obj[1].link_name, "progs.debug", sizeof(obj[1].link_name));
25	obj[1].link = progs_link;
26	return 0;
27}
28
29static struct bpf_preload_ops ops = {
30	.preload = preload,
31	.owner = THIS_MODULE,
32};
33
34static int load_skel(void)
35{
36	int err;
37
38	skel = iterators_bpf__open();
39	if (!skel)
40		return -ENOMEM;
41	err = iterators_bpf__load(skel);
42	if (err)
43		goto out;
44	err = iterators_bpf__attach(skel);
45	if (err)
46		goto out;
47	maps_link = bpf_link_get_from_fd(skel->links.dump_bpf_map_fd);
48	if (IS_ERR(maps_link)) {
49		err = PTR_ERR(maps_link);
50		goto out;
51	}
52	progs_link = bpf_link_get_from_fd(skel->links.dump_bpf_prog_fd);
53	if (IS_ERR(progs_link)) {
54		err = PTR_ERR(progs_link);
55		goto out;
56	}
57	/* Avoid taking over stdin/stdout/stderr of init process. Zeroing out
58	 * makes skel_closenz() a no-op later in iterators_bpf__destroy().
59	 */
60	close_fd(skel->links.dump_bpf_map_fd);
61	skel->links.dump_bpf_map_fd = 0;
62	close_fd(skel->links.dump_bpf_prog_fd);
63	skel->links.dump_bpf_prog_fd = 0;
64	return 0;
65out:
66	free_links_and_skel();
67	return err;
68}
69
70static int __init load(void)
71{
72	int err;
73
74	err = load_skel();
75	if (err)
76		return err;
77	bpf_preload_ops = &ops;
78	return err;
79}
80
81static void __exit fini(void)
82{
83	bpf_preload_ops = NULL;
84	free_links_and_skel();
85}
86late_initcall(load);
87module_exit(fini);
88MODULE_LICENSE("GPL");