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 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 (btf_record_has_field(inner_map->record, BPF_SPIN_LOCK)) { 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->record = btf_record_dup(inner_map->record); 54 if (IS_ERR(inner_map_meta->record)) { 55 /* btf_record_dup returns NULL or valid pointer in case of 56 * invalid/empty/valid, but ERR_PTR in case of errors. During 57 * equality NULL or IS_ERR is equivalent. 58 */ 59 fdput(f); 60 return ERR_CAST(inner_map_meta->record); 61 } 62 if (inner_map->btf) { 63 btf_get(inner_map->btf); 64 inner_map_meta->btf = inner_map->btf; 65 } 66 67 /* Misc members not needed in bpf_map_meta_equal() check. */ 68 inner_map_meta->ops = inner_map->ops; 69 if (inner_map->ops == &array_map_ops) { 70 inner_map_meta->bypass_spec_v1 = inner_map->bypass_spec_v1; 71 container_of(inner_map_meta, struct bpf_array, map)->index_mask = 72 container_of(inner_map, struct bpf_array, map)->index_mask; 73 } 74 75 fdput(f); 76 return inner_map_meta; 77 } 78 79 void bpf_map_meta_free(struct bpf_map *map_meta) 80 { 81 bpf_map_free_record(map_meta); 82 btf_put(map_meta->btf); 83 kfree(map_meta); 84 } 85 86 bool bpf_map_meta_equal(const struct bpf_map *meta0, 87 const struct bpf_map *meta1) 88 { 89 /* No need to compare ops because it is covered by map_type */ 90 return meta0->map_type == meta1->map_type && 91 meta0->key_size == meta1->key_size && 92 meta0->value_size == meta1->value_size && 93 meta0->map_flags == meta1->map_flags && 94 btf_record_equal(meta0->record, meta1->record); 95 } 96 97 void *bpf_map_fd_get_ptr(struct bpf_map *map, 98 struct file *map_file /* not used */, 99 int ufd) 100 { 101 struct bpf_map *inner_map, *inner_map_meta; 102 struct fd f; 103 104 f = fdget(ufd); 105 inner_map = __bpf_map_get(f); 106 if (IS_ERR(inner_map)) 107 return inner_map; 108 109 inner_map_meta = map->inner_map_meta; 110 if (inner_map_meta->ops->map_meta_equal(inner_map_meta, inner_map)) 111 bpf_map_inc(inner_map); 112 else 113 inner_map = ERR_PTR(-EINVAL); 114 115 fdput(f); 116 return inner_map; 117 } 118 119 void bpf_map_fd_put_ptr(void *ptr) 120 { 121 /* ptr->ops->map_free() has to go through one 122 * rcu grace period by itself. 123 */ 124 bpf_map_put(ptr); 125 } 126 127 u32 bpf_map_fd_sys_lookup_elem(void *ptr) 128 { 129 return ((struct bpf_map *)ptr)->id; 130 } 131