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
bpf_map_meta_alloc(int inner_map_ufd)10 struct 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;
91 free_rec:
92 btf_record_free(inner_map_meta->record);
93 free:
94 kfree(inner_map_meta);
95 put:
96 fdput(f);
97 return ERR_PTR(ret);
98 }
99
bpf_map_meta_free(struct bpf_map * map_meta)100 void 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
bpf_map_meta_equal(const struct bpf_map * meta0,const struct bpf_map * meta1)108 bool 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
bpf_map_fd_get_ptr(struct bpf_map * map,struct file * map_file,int ufd)119 void *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
bpf_map_fd_put_ptr(void * ptr)141 void 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
bpf_map_fd_sys_lookup_elem(void * ptr)149 u32 bpf_map_fd_sys_lookup_elem(void *ptr)
150 {
151 return ((struct bpf_map *)ptr)->id;
152 }
153