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_GLOBAL_SINGLE(btf_bpf_map_id, struct, bpf_map)
 82
 83static const struct bpf_iter_seq_info bpf_map_seq_info = {
 84	.seq_ops		= &bpf_map_seq_ops,
 85	.init_seq_private	= NULL,
 86	.fini_seq_private	= NULL,
 87	.seq_priv_size		= sizeof(struct bpf_iter_seq_map_info),
 88};
 89
 90static struct bpf_iter_reg bpf_map_reg_info = {
 91	.target			= "bpf_map",
 92	.ctx_arg_info_size	= 1,
 93	.ctx_arg_info		= {
 94		{ offsetof(struct bpf_iter__bpf_map, map),
 95		  PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED },
 96	},
 97	.seq_info		= &bpf_map_seq_info,
 98};
 99
100static int bpf_iter_attach_map(struct bpf_prog *prog,
101			       union bpf_iter_link_info *linfo,
102			       struct bpf_iter_aux_info *aux)
103{
104	u32 key_acc_size, value_acc_size, key_size, value_size;
105	struct bpf_map *map;
106	bool is_percpu = false;
107	int err = -EINVAL;
108
109	if (!linfo->map.map_fd)
110		return -EBADF;
111
112	map = bpf_map_get_with_uref(linfo->map.map_fd);
113	if (IS_ERR(map))
114		return PTR_ERR(map);
115
116	if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
117	    map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH ||
118	    map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
119		is_percpu = true;
120	else if (map->map_type != BPF_MAP_TYPE_HASH &&
121		 map->map_type != BPF_MAP_TYPE_LRU_HASH &&
122		 map->map_type != BPF_MAP_TYPE_ARRAY)
123		goto put_map;
124
125	key_acc_size = prog->aux->max_rdonly_access;
126	value_acc_size = prog->aux->max_rdwr_access;
127	key_size = map->key_size;
128	if (!is_percpu)
129		value_size = map->value_size;
130	else
131		value_size = round_up(map->value_size, 8) * num_possible_cpus();
132
133	if (key_acc_size > key_size || value_acc_size > value_size) {
134		err = -EACCES;
135		goto put_map;
136	}
137
138	aux->map = map;
139	return 0;
140
141put_map:
142	bpf_map_put_with_uref(map);
143	return err;
144}
145
146static void bpf_iter_detach_map(struct bpf_iter_aux_info *aux)
147{
148	bpf_map_put_with_uref(aux->map);
149}
150
151void bpf_iter_map_show_fdinfo(const struct bpf_iter_aux_info *aux,
152			      struct seq_file *seq)
153{
154	seq_printf(seq, "map_id:\t%u\n", aux->map->id);
155}
156
157int bpf_iter_map_fill_link_info(const struct bpf_iter_aux_info *aux,
158				struct bpf_link_info *info)
159{
160	info->iter.map.map_id = aux->map->id;
161	return 0;
162}
163
164DEFINE_BPF_ITER_FUNC(bpf_map_elem, struct bpf_iter_meta *meta,
165		     struct bpf_map *map, void *key, void *value)
166
167static const struct bpf_iter_reg bpf_map_elem_reg_info = {
168	.target			= "bpf_map_elem",
169	.attach_target		= bpf_iter_attach_map,
170	.detach_target		= bpf_iter_detach_map,
171	.show_fdinfo		= bpf_iter_map_show_fdinfo,
172	.fill_link_info		= bpf_iter_map_fill_link_info,
173	.ctx_arg_info_size	= 2,
174	.ctx_arg_info		= {
175		{ offsetof(struct bpf_iter__bpf_map_elem, key),
176		  PTR_TO_BUF | PTR_MAYBE_NULL | MEM_RDONLY },
177		{ offsetof(struct bpf_iter__bpf_map_elem, value),
178		  PTR_TO_BUF | PTR_MAYBE_NULL },
179	},
180};
181
182static int __init bpf_map_iter_init(void)
183{
184	int ret;
185
186	bpf_map_reg_info.ctx_arg_info[0].btf_id = *btf_bpf_map_id;
187	ret = bpf_iter_reg_target(&bpf_map_reg_info);
188	if (ret)
189		return ret;
190
191	return bpf_iter_reg_target(&bpf_map_elem_reg_info);
192}
193
194late_initcall(bpf_map_iter_init);
195
196__bpf_kfunc_start_defs();
197
198__bpf_kfunc s64 bpf_map_sum_elem_count(const struct bpf_map *map)
199{
200	s64 *pcount;
201	s64 ret = 0;
202	int cpu;
203
204	if (!map || !map->elem_count)
205		return 0;
206
207	for_each_possible_cpu(cpu) {
208		pcount = per_cpu_ptr(map->elem_count, cpu);
209		ret += READ_ONCE(*pcount);
210	}
211	return ret;
212}
213
214__bpf_kfunc_end_defs();
215
216BTF_SET8_START(bpf_map_iter_kfunc_ids)
217BTF_ID_FLAGS(func, bpf_map_sum_elem_count, KF_TRUSTED_ARGS)
218BTF_SET8_END(bpf_map_iter_kfunc_ids)
219
220static const struct btf_kfunc_id_set bpf_map_iter_kfunc_set = {
221	.owner = THIS_MODULE,
222	.set   = &bpf_map_iter_kfunc_ids,
223};
224
225static int init_subsystem(void)
226{
227	return register_btf_kfunc_id_set(BPF_PROG_TYPE_UNSPEC, &bpf_map_iter_kfunc_set);
228}
229late_initcall(init_subsystem);