1// SPDX-License-Identifier: GPL-2.0-only
  2/* Copyright (c) 2017 Facebook
  3 */
  4#include <linux/slab.h>
  5#include <linux/bpf.h>
  6#include <linux/btf.h>
  7
  8#include "map_in_map.h"
  9
 10struct bpf_map *bpf_map_meta_alloc(int inner_map_ufd)
 11{
 12	struct bpf_map *inner_map, *inner_map_meta;
 13	u32 inner_map_meta_size;
 14	struct fd f;
 15	int ret;
 16
 17	f = fdget(inner_map_ufd);
 18	inner_map = __bpf_map_get(f);
 19	if (IS_ERR(inner_map))
 20		return inner_map;
 21
 22	/* Does not support >1 level map-in-map */
 23	if (inner_map->inner_map_meta) {
 24		ret = -EINVAL;
 25		goto put;
 26	}
 27
 28	if (!inner_map->ops->map_meta_equal) {
 29		ret = -ENOTSUPP;
 30		goto put;
 31	}
 32
 33	inner_map_meta_size = sizeof(*inner_map_meta);
 34	/* In some cases verifier needs to access beyond just base map. */
 35	if (inner_map->ops == &array_map_ops)
 36		inner_map_meta_size = sizeof(struct bpf_array);
 37
 38	inner_map_meta = kzalloc(inner_map_meta_size, GFP_USER);
 39	if (!inner_map_meta) {
 40		ret = -ENOMEM;
 41		goto put;
 42	}
 43
 44	inner_map_meta->map_type = inner_map->map_type;
 45	inner_map_meta->key_size = inner_map->key_size;
 46	inner_map_meta->value_size = inner_map->value_size;
 47	inner_map_meta->map_flags = inner_map->map_flags;
 48	inner_map_meta->max_entries = inner_map->max_entries;
 49
 50	inner_map_meta->record = btf_record_dup(inner_map->record);
 51	if (IS_ERR(inner_map_meta->record)) {
 52		/* btf_record_dup returns NULL or valid pointer in case of
 53		 * invalid/empty/valid, but ERR_PTR in case of errors. During
 54		 * equality NULL or IS_ERR is equivalent.
 55		 */
 56		ret = PTR_ERR(inner_map_meta->record);
 57		goto free;
 58	}
 59	if (inner_map_meta->record) {
 60		struct btf_field_offs *field_offs;
 61		/* If btf_record is !IS_ERR_OR_NULL, then field_offs is always
 62		 * valid.
 63		 */
 64		field_offs = kmemdup(inner_map->field_offs, sizeof(*inner_map->field_offs), GFP_KERNEL | __GFP_NOWARN);
 65		if (!field_offs) {
 66			ret = -ENOMEM;
 67			goto free_rec;
 68		}
 69		inner_map_meta->field_offs = field_offs;
 70	}
 71	/* Note: We must use the same BTF, as we also used btf_record_dup above
 72	 * which relies on BTF being same for both maps, as some members like
 73	 * record->fields.list_head have pointers like value_rec pointing into
 74	 * inner_map->btf.
 75	 */
 76	if (inner_map->btf) {
 77		btf_get(inner_map->btf);
 78		inner_map_meta->btf = inner_map->btf;
 79	}
 80
 81	/* Misc members not needed in bpf_map_meta_equal() check. */
 82	inner_map_meta->ops = inner_map->ops;
 83	if (inner_map->ops == &array_map_ops) {
 84		inner_map_meta->bypass_spec_v1 = inner_map->bypass_spec_v1;
 85		container_of(inner_map_meta, struct bpf_array, map)->index_mask =
 86		     container_of(inner_map, struct bpf_array, map)->index_mask;
 87	}
 88
 89	fdput(f);
 90	return inner_map_meta;
 91free_rec:
 92	btf_record_free(inner_map_meta->record);
 93free:
 94	kfree(inner_map_meta);
 95put:
 96	fdput(f);
 97	return ERR_PTR(ret);
 98}
 99
100void bpf_map_meta_free(struct bpf_map *map_meta)
101{
102	kfree(map_meta->field_offs);
103	bpf_map_free_record(map_meta);
104	btf_put(map_meta->btf);
105	kfree(map_meta);
106}
107
108bool bpf_map_meta_equal(const struct bpf_map *meta0,
109			const struct bpf_map *meta1)
110{
111	/* No need to compare ops because it is covered by map_type */
112	return meta0->map_type == meta1->map_type &&
113		meta0->key_size == meta1->key_size &&
114		meta0->value_size == meta1->value_size &&
115		meta0->map_flags == meta1->map_flags &&
116		btf_record_equal(meta0->record, meta1->record);
117}
118
119void *bpf_map_fd_get_ptr(struct bpf_map *map,
120			 struct file *map_file /* not used */,
121			 int ufd)
122{
123	struct bpf_map *inner_map, *inner_map_meta;
124	struct fd f;
125
126	f = fdget(ufd);
127	inner_map = __bpf_map_get(f);
128	if (IS_ERR(inner_map))
129		return inner_map;
130
131	inner_map_meta = map->inner_map_meta;
132	if (inner_map_meta->ops->map_meta_equal(inner_map_meta, inner_map))
133		bpf_map_inc(inner_map);
134	else
135		inner_map = ERR_PTR(-EINVAL);
136
137	fdput(f);
138	return inner_map;
139}
140
141void bpf_map_fd_put_ptr(void *ptr)
142{
143	/* ptr->ops->map_free() has to go through one
144	 * rcu grace period by itself.
145	 */
146	bpf_map_put(ptr);
147}
148
149u32 bpf_map_fd_sys_lookup_elem(void *ptr)
150{
151	return ((struct bpf_map *)ptr)->id;
152}