1// SPDX-License-Identifier: GPL-2.0-only
  2/* Copyright (c) 2020 Facebook */
  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_map_info {
 10	u32 map_id;
 11};
 12
 13static void *bpf_map_seq_start(struct seq_file *seq, loff_t *pos)
 14{
 15	struct bpf_iter_seq_map_info *info = seq->private;
 16	struct bpf_map *map;
 17
 18	map = bpf_map_get_curr_or_next(&info->map_id);
 19	if (!map)
 20		return NULL;
 21
 22	if (*pos == 0)
 23		++*pos;
 24	return map;
 25}
 26
 27static void *bpf_map_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 28{
 29	struct bpf_iter_seq_map_info *info = seq->private;
 30
 31	++*pos;
 32	++info->map_id;
 33	bpf_map_put((struct bpf_map *)v);
 34	return bpf_map_get_curr_or_next(&info->map_id);
 35}
 36
 37struct bpf_iter__bpf_map {
 38	__bpf_md_ptr(struct bpf_iter_meta *, meta);
 39	__bpf_md_ptr(struct bpf_map *, map);
 40};
 41
 42DEFINE_BPF_ITER_FUNC(bpf_map, struct bpf_iter_meta *meta, struct bpf_map *map)
 43
 44static int __bpf_map_seq_show(struct seq_file *seq, void *v, bool in_stop)
 45{
 46	struct bpf_iter__bpf_map ctx;
 47	struct bpf_iter_meta meta;
 48	struct bpf_prog *prog;
 49	int ret = 0;
 50
 51	ctx.meta = &meta;
 52	ctx.map = 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_map_seq_show(struct seq_file *seq, void *v)
 62{
 63	return __bpf_map_seq_show(seq, v, false);
 64}
 65
 66static void bpf_map_seq_stop(struct seq_file *seq, void *v)
 67{
 68	if (!v)
 69		(void)__bpf_map_seq_show(seq, v, true);
 70	else
 71		bpf_map_put((struct bpf_map *)v);
 72}
 73
 74static const struct seq_operations bpf_map_seq_ops = {
 75	.start	= bpf_map_seq_start,
 76	.next	= bpf_map_seq_next,
 77	.stop	= bpf_map_seq_stop,
 78	.show	= bpf_map_seq_show,
 79};
 80
 81BTF_ID_LIST(btf_bpf_map_id)
 82BTF_ID(struct, bpf_map)
 83
 84static const struct bpf_iter_seq_info bpf_map_seq_info = {
 85	.seq_ops		= &bpf_map_seq_ops,
 86	.init_seq_private	= NULL,
 87	.fini_seq_private	= NULL,
 88	.seq_priv_size		= sizeof(struct bpf_iter_seq_map_info),
 89};
 90
 91static struct bpf_iter_reg bpf_map_reg_info = {
 92	.target			= "bpf_map",
 93	.ctx_arg_info_size	= 1,
 94	.ctx_arg_info		= {
 95		{ offsetof(struct bpf_iter__bpf_map, map),
 96		  PTR_TO_BTF_ID_OR_NULL },
 97	},
 98	.seq_info		= &bpf_map_seq_info,
 99};
100
101static int bpf_iter_attach_map(struct bpf_prog *prog,
102			       union bpf_iter_link_info *linfo,
103			       struct bpf_iter_aux_info *aux)
104{
105	u32 key_acc_size, value_acc_size, key_size, value_size;
106	struct bpf_map *map;
107	bool is_percpu = false;
108	int err = -EINVAL;
109
110	if (!linfo->map.map_fd)
111		return -EBADF;
112
113	map = bpf_map_get_with_uref(linfo->map.map_fd);
114	if (IS_ERR(map))
115		return PTR_ERR(map);
116
117	if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
118	    map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH ||
119	    map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
120		is_percpu = true;
121	else if (map->map_type != BPF_MAP_TYPE_HASH &&
122		 map->map_type != BPF_MAP_TYPE_LRU_HASH &&
123		 map->map_type != BPF_MAP_TYPE_ARRAY)
124		goto put_map;
125
126	key_acc_size = prog->aux->max_rdonly_access;
127	value_acc_size = prog->aux->max_rdwr_access;
128	key_size = map->key_size;
129	if (!is_percpu)
130		value_size = map->value_size;
131	else
132		value_size = round_up(map->value_size, 8) * num_possible_cpus();
133
134	if (key_acc_size > key_size || value_acc_size > value_size) {
135		err = -EACCES;
136		goto put_map;
137	}
138
139	aux->map = map;
140	return 0;
141
142put_map:
143	bpf_map_put_with_uref(map);
144	return err;
145}
146
147static void bpf_iter_detach_map(struct bpf_iter_aux_info *aux)
148{
149	bpf_map_put_with_uref(aux->map);
150}
151
152void bpf_iter_map_show_fdinfo(const struct bpf_iter_aux_info *aux,
153			      struct seq_file *seq)
154{
155	seq_printf(seq, "map_id:\t%u\n", aux->map->id);
156}
157
158int bpf_iter_map_fill_link_info(const struct bpf_iter_aux_info *aux,
159				struct bpf_link_info *info)
160{
161	info->iter.map.map_id = aux->map->id;
162	return 0;
163}
164
165DEFINE_BPF_ITER_FUNC(bpf_map_elem, struct bpf_iter_meta *meta,
166		     struct bpf_map *map, void *key, void *value)
167
168static const struct bpf_iter_reg bpf_map_elem_reg_info = {
169	.target			= "bpf_map_elem",
170	.attach_target		= bpf_iter_attach_map,
171	.detach_target		= bpf_iter_detach_map,
172	.show_fdinfo		= bpf_iter_map_show_fdinfo,
173	.fill_link_info		= bpf_iter_map_fill_link_info,
174	.ctx_arg_info_size	= 2,
175	.ctx_arg_info		= {
176		{ offsetof(struct bpf_iter__bpf_map_elem, key),
177		  PTR_TO_BUF | PTR_MAYBE_NULL | MEM_RDONLY },
178		{ offsetof(struct bpf_iter__bpf_map_elem, value),
179		  PTR_TO_BUF | PTR_MAYBE_NULL },
180	},
181};
182
183static int __init bpf_map_iter_init(void)
184{
185	int ret;
186
187	bpf_map_reg_info.ctx_arg_info[0].btf_id = *btf_bpf_map_id;
188	ret = bpf_iter_reg_target(&bpf_map_reg_info);
189	if (ret)
190		return ret;
191
192	return bpf_iter_reg_target(&bpf_map_elem_reg_info);
193}
194
195late_initcall(bpf_map_iter_init);