1 /* Copyright (c) 2017 Facebook
2 *
3 * This program is free software; you can redistribute it and/or
4 * modify it under the terms of version 2 of the GNU General Public
5 * License as published by the Free Software Foundation.
6 */
7 #include <linux/slab.h>
8 #include <linux/bpf.h>
9
10 #include "map_in_map.h"
11
bpf_map_meta_alloc(int inner_map_ufd)12 struct bpf_map *bpf_map_meta_alloc(int inner_map_ufd)
13 {
14 struct bpf_map *inner_map, *inner_map_meta;
15 u32 inner_map_meta_size;
16 struct fd f;
17
18 f = fdget(inner_map_ufd);
19 inner_map = __bpf_map_get(f);
20 if (IS_ERR(inner_map))
21 return inner_map;
22
23 /* prog_array->owner_prog_type and owner_jited
24 * is a runtime binding. Doing static check alone
25 * in the verifier is not enough.
26 */
27 if (inner_map->map_type == BPF_MAP_TYPE_PROG_ARRAY) {
28 fdput(f);
29 return ERR_PTR(-ENOTSUPP);
30 }
31
32 /* Does not support >1 level map-in-map */
33 if (inner_map->inner_map_meta) {
34 fdput(f);
35 return ERR_PTR(-EINVAL);
36 }
37
38 inner_map_meta_size = sizeof(*inner_map_meta);
39 /* In some cases verifier needs to access beyond just base map. */
40 if (inner_map->ops == &array_map_ops)
41 inner_map_meta_size = sizeof(struct bpf_array);
42
43 inner_map_meta = kzalloc(inner_map_meta_size, GFP_USER);
44 if (!inner_map_meta) {
45 fdput(f);
46 return ERR_PTR(-ENOMEM);
47 }
48
49 inner_map_meta->map_type = inner_map->map_type;
50 inner_map_meta->key_size = inner_map->key_size;
51 inner_map_meta->value_size = inner_map->value_size;
52 inner_map_meta->map_flags = inner_map->map_flags;
53 inner_map_meta->max_entries = inner_map->max_entries;
54
55 /* Misc members not needed in bpf_map_meta_equal() check. */
56 inner_map_meta->ops = inner_map->ops;
57 if (inner_map->ops == &array_map_ops) {
58 inner_map_meta->unpriv_array = inner_map->unpriv_array;
59 container_of(inner_map_meta, struct bpf_array, map)->index_mask =
60 container_of(inner_map, struct bpf_array, map)->index_mask;
61 }
62
63 fdput(f);
64 return inner_map_meta;
65 }
66
bpf_map_meta_free(struct bpf_map * map_meta)67 void bpf_map_meta_free(struct bpf_map *map_meta)
68 {
69 kfree(map_meta);
70 }
71
bpf_map_meta_equal(const struct bpf_map * meta0,const struct bpf_map * meta1)72 bool bpf_map_meta_equal(const struct bpf_map *meta0,
73 const struct bpf_map *meta1)
74 {
75 /* No need to compare ops because it is covered by map_type */
76 return meta0->map_type == meta1->map_type &&
77 meta0->key_size == meta1->key_size &&
78 meta0->value_size == meta1->value_size &&
79 meta0->map_flags == meta1->map_flags &&
80 meta0->max_entries == meta1->max_entries;
81 }
82
bpf_map_fd_get_ptr(struct bpf_map * map,struct file * map_file,int ufd)83 void *bpf_map_fd_get_ptr(struct bpf_map *map,
84 struct file *map_file /* not used */,
85 int ufd)
86 {
87 struct bpf_map *inner_map;
88 struct fd f;
89
90 f = fdget(ufd);
91 inner_map = __bpf_map_get(f);
92 if (IS_ERR(inner_map))
93 return inner_map;
94
95 if (bpf_map_meta_equal(map->inner_map_meta, inner_map))
96 inner_map = bpf_map_inc(inner_map, false);
97 else
98 inner_map = ERR_PTR(-EINVAL);
99
100 fdput(f);
101 return inner_map;
102 }
103
bpf_map_fd_put_ptr(void * ptr)104 void bpf_map_fd_put_ptr(void *ptr)
105 {
106 /* ptr->ops->map_free() has to go through one
107 * rcu grace period by itself.
108 */
109 bpf_map_put(ptr);
110 }
111
bpf_map_fd_sys_lookup_elem(void * ptr)112 u32 bpf_map_fd_sys_lookup_elem(void *ptr)
113 {
114 return ((struct bpf_map *)ptr)->id;
115 }
116