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 
16 	f = fdget(inner_map_ufd);
17 	inner_map = __bpf_map_get(f);
18 	if (IS_ERR(inner_map))
19 		return inner_map;
20 
21 	/* Does not support >1 level map-in-map */
22 	if (inner_map->inner_map_meta) {
23 		fdput(f);
24 		return ERR_PTR(-EINVAL);
25 	}
26 
27 	if (!inner_map->ops->map_meta_equal) {
28 		fdput(f);
29 		return ERR_PTR(-ENOTSUPP);
30 	}
31 
32 	if (map_value_has_spin_lock(inner_map)) {
33 		fdput(f);
34 		return ERR_PTR(-ENOTSUPP);
35 	}
36 
37 	inner_map_meta_size = sizeof(*inner_map_meta);
38 	/* In some cases verifier needs to access beyond just base map. */
39 	if (inner_map->ops == &array_map_ops)
40 		inner_map_meta_size = sizeof(struct bpf_array);
41 
42 	inner_map_meta = kzalloc(inner_map_meta_size, GFP_USER);
43 	if (!inner_map_meta) {
44 		fdput(f);
45 		return ERR_PTR(-ENOMEM);
46 	}
47 
48 	inner_map_meta->map_type = inner_map->map_type;
49 	inner_map_meta->key_size = inner_map->key_size;
50 	inner_map_meta->value_size = inner_map->value_size;
51 	inner_map_meta->map_flags = inner_map->map_flags;
52 	inner_map_meta->max_entries = inner_map->max_entries;
53 	inner_map_meta->spin_lock_off = inner_map->spin_lock_off;
54 	inner_map_meta->timer_off = inner_map->timer_off;
55 	inner_map_meta->kptr_off_tab = bpf_map_copy_kptr_off_tab(inner_map);
56 	if (inner_map->btf) {
57 		btf_get(inner_map->btf);
58 		inner_map_meta->btf = inner_map->btf;
59 	}
60 
61 	/* Misc members not needed in bpf_map_meta_equal() check. */
62 	inner_map_meta->ops = inner_map->ops;
63 	if (inner_map->ops == &array_map_ops) {
64 		inner_map_meta->bypass_spec_v1 = inner_map->bypass_spec_v1;
65 		container_of(inner_map_meta, struct bpf_array, map)->index_mask =
66 		     container_of(inner_map, struct bpf_array, map)->index_mask;
67 	}
68 
69 	fdput(f);
70 	return inner_map_meta;
71 }
72 
bpf_map_meta_free(struct bpf_map * map_meta)73 void bpf_map_meta_free(struct bpf_map *map_meta)
74 {
75 	bpf_map_free_kptr_off_tab(map_meta);
76 	btf_put(map_meta->btf);
77 	kfree(map_meta);
78 }
79 
bpf_map_meta_equal(const struct bpf_map * meta0,const struct bpf_map * meta1)80 bool bpf_map_meta_equal(const struct bpf_map *meta0,
81 			const struct bpf_map *meta1)
82 {
83 	/* No need to compare ops because it is covered by map_type */
84 	return meta0->map_type == meta1->map_type &&
85 		meta0->key_size == meta1->key_size &&
86 		meta0->value_size == meta1->value_size &&
87 		meta0->timer_off == meta1->timer_off &&
88 		meta0->map_flags == meta1->map_flags &&
89 		bpf_map_equal_kptr_off_tab(meta0, meta1);
90 }
91 
bpf_map_fd_get_ptr(struct bpf_map * map,struct file * map_file,int ufd)92 void *bpf_map_fd_get_ptr(struct bpf_map *map,
93 			 struct file *map_file /* not used */,
94 			 int ufd)
95 {
96 	struct bpf_map *inner_map, *inner_map_meta;
97 	struct fd f;
98 
99 	f = fdget(ufd);
100 	inner_map = __bpf_map_get(f);
101 	if (IS_ERR(inner_map))
102 		return inner_map;
103 
104 	inner_map_meta = map->inner_map_meta;
105 	if (inner_map_meta->ops->map_meta_equal(inner_map_meta, inner_map))
106 		bpf_map_inc(inner_map);
107 	else
108 		inner_map = ERR_PTR(-EINVAL);
109 
110 	fdput(f);
111 	return inner_map;
112 }
113 
bpf_map_fd_put_ptr(void * ptr)114 void bpf_map_fd_put_ptr(void *ptr)
115 {
116 	/* ptr->ops->map_free() has to go through one
117 	 * rcu grace period by itself.
118 	 */
119 	bpf_map_put(ptr);
120 }
121 
bpf_map_fd_sys_lookup_elem(void * ptr)122 u32 bpf_map_fd_sys_lookup_elem(void *ptr)
123 {
124 	return ((struct bpf_map *)ptr)->id;
125 }
126