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 CLASS(fd, f)(inner_map_ufd);
15
16 inner_map = __bpf_map_get(f);
17 if (IS_ERR(inner_map))
18 return inner_map;
19
20 /* Does not support >1 level map-in-map */
21 if (inner_map->inner_map_meta)
22 return ERR_PTR(-EINVAL);
23
24 if (!inner_map->ops->map_meta_equal)
25 return ERR_PTR(-ENOTSUPP);
26
27 inner_map_meta_size = sizeof(*inner_map_meta);
28 /* In some cases verifier needs to access beyond just base map. */
29 if (inner_map->ops == &array_map_ops || inner_map->ops == &percpu_array_map_ops)
30 inner_map_meta_size = sizeof(struct bpf_array);
31
32 inner_map_meta = kzalloc(inner_map_meta_size, GFP_USER);
33 if (!inner_map_meta)
34 return ERR_PTR(-ENOMEM);
35
36 inner_map_meta->map_type = inner_map->map_type;
37 inner_map_meta->key_size = inner_map->key_size;
38 inner_map_meta->value_size = inner_map->value_size;
39 inner_map_meta->map_flags = inner_map->map_flags;
40 inner_map_meta->max_entries = inner_map->max_entries;
41
42 inner_map_meta->record = btf_record_dup(inner_map->record);
43 if (IS_ERR(inner_map_meta->record)) {
44 /* btf_record_dup returns NULL or valid pointer in case of
45 * invalid/empty/valid, but ERR_PTR in case of errors. During
46 * equality NULL or IS_ERR is equivalent.
47 */
48 struct bpf_map *ret = ERR_CAST(inner_map_meta->record);
49 kfree(inner_map_meta);
50 return ret;
51 }
52 /* Note: We must use the same BTF, as we also used btf_record_dup above
53 * which relies on BTF being same for both maps, as some members like
54 * record->fields.list_head have pointers like value_rec pointing into
55 * inner_map->btf.
56 */
57 if (inner_map->btf) {
58 btf_get(inner_map->btf);
59 inner_map_meta->btf = inner_map->btf;
60 }
61
62 /* Misc members not needed in bpf_map_meta_equal() check. */
63 inner_map_meta->ops = inner_map->ops;
64 if (inner_map->ops == &array_map_ops || inner_map->ops == &percpu_array_map_ops) {
65 struct bpf_array *inner_array_meta =
66 container_of(inner_map_meta, struct bpf_array, map);
67 struct bpf_array *inner_array = container_of(inner_map, struct bpf_array, map);
68
69 inner_array_meta->index_mask = inner_array->index_mask;
70 inner_array_meta->elem_size = inner_array->elem_size;
71 inner_map_meta->bypass_spec_v1 = inner_map->bypass_spec_v1;
72 }
73 return inner_map_meta;
74 }
75
bpf_map_meta_free(struct bpf_map * map_meta)76 void bpf_map_meta_free(struct bpf_map *map_meta)
77 {
78 bpf_map_free_record(map_meta);
79 btf_put(map_meta->btf);
80 kfree(map_meta);
81 }
82
bpf_map_meta_equal(const struct bpf_map * meta0,const struct bpf_map * meta1)83 bool bpf_map_meta_equal(const struct bpf_map *meta0,
84 const struct bpf_map *meta1)
85 {
86 /* No need to compare ops because it is covered by map_type */
87 return meta0->map_type == meta1->map_type &&
88 meta0->key_size == meta1->key_size &&
89 meta0->value_size == meta1->value_size &&
90 meta0->map_flags == meta1->map_flags &&
91 btf_record_equal(meta0->record, meta1->record);
92 }
93
bpf_map_fd_get_ptr(struct bpf_map * map,struct file * map_file,int ufd)94 void *bpf_map_fd_get_ptr(struct bpf_map *map,
95 struct file *map_file /* not used */,
96 int ufd)
97 {
98 struct bpf_map *inner_map, *inner_map_meta;
99 CLASS(fd, f)(ufd);
100
101 inner_map = __bpf_map_get(f);
102 if (IS_ERR(inner_map))
103 return inner_map;
104
105 inner_map_meta = map->inner_map_meta;
106 if (inner_map_meta->ops->map_meta_equal(inner_map_meta, inner_map))
107 bpf_map_inc(inner_map);
108 else
109 inner_map = ERR_PTR(-EINVAL);
110
111 return inner_map;
112 }
113
bpf_map_fd_put_ptr(struct bpf_map * map,void * ptr,bool need_defer)114 void bpf_map_fd_put_ptr(struct bpf_map *map, void *ptr, bool need_defer)
115 {
116 struct bpf_map *inner_map = ptr;
117
118 /* Defer the freeing of inner map according to the sleepable attribute
119 * of bpf program which owns the outer map, so unnecessary waiting for
120 * RCU tasks trace grace period can be avoided.
121 */
122 if (need_defer) {
123 if (atomic64_read(&map->sleepable_refcnt))
124 WRITE_ONCE(inner_map->free_after_mult_rcu_gp, true);
125 else
126 WRITE_ONCE(inner_map->free_after_rcu_gp, true);
127 }
128 bpf_map_put(inner_map);
129 }
130
bpf_map_fd_sys_lookup_elem(void * ptr)131 u32 bpf_map_fd_sys_lookup_elem(void *ptr)
132 {
133 return ((struct bpf_map *)ptr)->id;
134 }
135