1// SPDX-License-Identifier: GPL-2.0-only
2/* Copyright (c) 2022 Red Hat, Inc. */
3#include <linux/bpf.h>
4#include <linux/fs.h>
5#include <linux/filter.h>
6#include <linux/kernel.h>
7#include <linux/btf_ids.h>
8
9struct bpf_iter_seq_link_info {
10	u32 link_id;
11};
12
13static void *bpf_link_seq_start(struct seq_file *seq, loff_t *pos)
14{
15	struct bpf_iter_seq_link_info *info = seq->private;
16	struct bpf_link *link;
17
18	link = bpf_link_get_curr_or_next(&info->link_id);
19	if (!link)
20		return NULL;
21
22	if (*pos == 0)
23		++*pos;
24	return link;
25}
26
27static void *bpf_link_seq_next(struct seq_file *seq, void *v, loff_t *pos)
28{
29	struct bpf_iter_seq_link_info *info = seq->private;
30
31	++*pos;
32	++info->link_id;
33	bpf_link_put((struct bpf_link *)v);
34	return bpf_link_get_curr_or_next(&info->link_id);
35}
36
37struct bpf_iter__bpf_link {
38	__bpf_md_ptr(struct bpf_iter_meta *, meta);
39	__bpf_md_ptr(struct bpf_link *, link);
40};
41
42DEFINE_BPF_ITER_FUNC(bpf_link, struct bpf_iter_meta *meta, struct bpf_link *link)
43
44static int __bpf_link_seq_show(struct seq_file *seq, void *v, bool in_stop)
45{
46	struct bpf_iter__bpf_link ctx;
47	struct bpf_iter_meta meta;
48	struct bpf_prog *prog;
49	int ret = 0;
50
51	ctx.meta = &meta;
52	ctx.link = v;
53	meta.seq = seq;
54	prog = bpf_iter_get_info(&meta, in_stop);
55	if (prog)
56		ret = bpf_iter_run_prog(prog, &ctx);
57
58	return ret;
59}
60
61static int bpf_link_seq_show(struct seq_file *seq, void *v)
62{
63	return __bpf_link_seq_show(seq, v, false);
64}
65
66static void bpf_link_seq_stop(struct seq_file *seq, void *v)
67{
68	if (!v)
69		(void)__bpf_link_seq_show(seq, v, true);
70	else
71		bpf_link_put((struct bpf_link *)v);
72}
73
74static const struct seq_operations bpf_link_seq_ops = {
75	.start	= bpf_link_seq_start,
76	.next	= bpf_link_seq_next,
77	.stop	= bpf_link_seq_stop,
78	.show	= bpf_link_seq_show,
79};
80
81BTF_ID_LIST(btf_bpf_link_id)
82BTF_ID(struct, bpf_link)
83
84static const struct bpf_iter_seq_info bpf_link_seq_info = {
85	.seq_ops		= &bpf_link_seq_ops,
86	.init_seq_private	= NULL,
87	.fini_seq_private	= NULL,
88	.seq_priv_size		= sizeof(struct bpf_iter_seq_link_info),
89};
90
91static struct bpf_iter_reg bpf_link_reg_info = {
92	.target			= "bpf_link",
93	.ctx_arg_info_size	= 1,
94	.ctx_arg_info		= {
95		{ offsetof(struct bpf_iter__bpf_link, link),
96		  PTR_TO_BTF_ID_OR_NULL },
97	},
98	.seq_info		= &bpf_link_seq_info,
99};
100
101static int __init bpf_link_iter_init(void)
102{
103	bpf_link_reg_info.ctx_arg_info[0].btf_id = *btf_bpf_link_id;
104	return bpf_iter_reg_target(&bpf_link_reg_info);
105}
106
107late_initcall(bpf_link_iter_init);
108