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 | |
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(fd: inner_map_ufd); |
18 | inner_map = __bpf_map_get(f); |
19 | if (IS_ERR(ptr: 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(size: 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(rec: inner_map->record); |
51 | if (IS_ERR(ptr: 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(ptr: inner_map_meta->record); |
57 | goto free; |
58 | } |
59 | /* Note: We must use the same BTF, as we also used btf_record_dup above |
60 | * which relies on BTF being same for both maps, as some members like |
61 | * record->fields.list_head have pointers like value_rec pointing into |
62 | * inner_map->btf. |
63 | */ |
64 | if (inner_map->btf) { |
65 | btf_get(btf: inner_map->btf); |
66 | inner_map_meta->btf = inner_map->btf; |
67 | } |
68 | |
69 | /* Misc members not needed in bpf_map_meta_equal() check. */ |
70 | inner_map_meta->ops = inner_map->ops; |
71 | if (inner_map->ops == &array_map_ops) { |
72 | struct bpf_array *inner_array_meta = |
73 | container_of(inner_map_meta, struct bpf_array, map); |
74 | struct bpf_array *inner_array = container_of(inner_map, struct bpf_array, map); |
75 | |
76 | inner_array_meta->index_mask = inner_array->index_mask; |
77 | inner_array_meta->elem_size = inner_array->elem_size; |
78 | inner_map_meta->bypass_spec_v1 = inner_map->bypass_spec_v1; |
79 | } |
80 | |
81 | fdput(fd: f); |
82 | return inner_map_meta; |
83 | free: |
84 | kfree(objp: inner_map_meta); |
85 | put: |
86 | fdput(fd: f); |
87 | return ERR_PTR(error: ret); |
88 | } |
89 | |
90 | void bpf_map_meta_free(struct bpf_map *map_meta) |
91 | { |
92 | bpf_map_free_record(map: map_meta); |
93 | btf_put(btf: map_meta->btf); |
94 | kfree(objp: map_meta); |
95 | } |
96 | |
97 | bool bpf_map_meta_equal(const struct bpf_map *meta0, |
98 | const struct bpf_map *meta1) |
99 | { |
100 | /* No need to compare ops because it is covered by map_type */ |
101 | return meta0->map_type == meta1->map_type && |
102 | meta0->key_size == meta1->key_size && |
103 | meta0->value_size == meta1->value_size && |
104 | meta0->map_flags == meta1->map_flags && |
105 | btf_record_equal(rec_a: meta0->record, rec_b: meta1->record); |
106 | } |
107 | |
108 | void *bpf_map_fd_get_ptr(struct bpf_map *map, |
109 | struct file *map_file /* not used */, |
110 | int ufd) |
111 | { |
112 | struct bpf_map *inner_map, *inner_map_meta; |
113 | struct fd f; |
114 | |
115 | f = fdget(fd: ufd); |
116 | inner_map = __bpf_map_get(f); |
117 | if (IS_ERR(ptr: inner_map)) |
118 | return inner_map; |
119 | |
120 | inner_map_meta = map->inner_map_meta; |
121 | if (inner_map_meta->ops->map_meta_equal(inner_map_meta, inner_map)) |
122 | bpf_map_inc(map: inner_map); |
123 | else |
124 | inner_map = ERR_PTR(error: -EINVAL); |
125 | |
126 | fdput(fd: f); |
127 | return inner_map; |
128 | } |
129 | |
130 | void bpf_map_fd_put_ptr(void *ptr) |
131 | { |
132 | /* ptr->ops->map_free() has to go through one |
133 | * rcu grace period by itself. |
134 | */ |
135 | bpf_map_put(map: ptr); |
136 | } |
137 | |
138 | u32 bpf_map_fd_sys_lookup_elem(void *ptr) |
139 | { |
140 | return ((struct bpf_map *)ptr)->id; |
141 | } |
142 | |