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);