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