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 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 /* Note: We must use the same BTF, as we also used btf_record_dup above 60 * which relies on BTF being same for both maps, as some members like 61 * record->fields.list_head have pointers like value_rec pointing into 62 * inner_map->btf. 63 */ 64 if (inner_map->btf) { 65 btf_get(inner_map->btf); 66 inner_map_meta->btf = inner_map->btf; 67 } 68 69 /* Misc members not needed in bpf_map_meta_equal() check. */ 70 inner_map_meta->ops = inner_map->ops; 71 if (inner_map->ops == &array_map_ops) { 72 struct bpf_array *inner_array_meta = 73 container_of(inner_map_meta, struct bpf_array, map); 74 struct bpf_array *inner_array = container_of(inner_map, struct bpf_array, map); 75 76 inner_array_meta->index_mask = inner_array->index_mask; 77 inner_array_meta->elem_size = inner_array->elem_size; 78 inner_map_meta->bypass_spec_v1 = inner_map->bypass_spec_v1; 79 } 80 81 fdput(f); 82 return inner_map_meta; 83 free: 84 kfree(inner_map_meta); 85 put: 86 fdput(f); 87 return ERR_PTR(ret); 88 } 89 90 void bpf_map_meta_free(struct bpf_map *map_meta) 91 { 92 bpf_map_free_record(map_meta); 93 btf_put(map_meta->btf); 94 kfree(map_meta); 95 } 96 97 bool bpf_map_meta_equal(const struct bpf_map *meta0, 98 const struct bpf_map *meta1) 99 { 100 /* No need to compare ops because it is covered by map_type */ 101 return meta0->map_type == meta1->map_type && 102 meta0->key_size == meta1->key_size && 103 meta0->value_size == meta1->value_size && 104 meta0->map_flags == meta1->map_flags && 105 btf_record_equal(meta0->record, meta1->record); 106 } 107 108 void *bpf_map_fd_get_ptr(struct bpf_map *map, 109 struct file *map_file /* not used */, 110 int ufd) 111 { 112 struct bpf_map *inner_map, *inner_map_meta; 113 struct fd f; 114 115 f = fdget(ufd); 116 inner_map = __bpf_map_get(f); 117 if (IS_ERR(inner_map)) 118 return inner_map; 119 120 inner_map_meta = map->inner_map_meta; 121 if (inner_map_meta->ops->map_meta_equal(inner_map_meta, inner_map)) 122 bpf_map_inc(inner_map); 123 else 124 inner_map = ERR_PTR(-EINVAL); 125 126 fdput(f); 127 return inner_map; 128 } 129 130 void bpf_map_fd_put_ptr(struct bpf_map *map, void *ptr, bool need_defer) 131 { 132 struct bpf_map *inner_map = ptr; 133 134 /* The inner map may still be used by both non-sleepable and sleepable 135 * bpf program, so free it after one RCU grace period and one tasks 136 * trace RCU grace period. 137 */ 138 if (need_defer) 139 WRITE_ONCE(inner_map->free_after_mult_rcu_gp, true); 140 bpf_map_put(inner_map); 141 } 142 143 u32 bpf_map_fd_sys_lookup_elem(void *ptr) 144 { 145 return ((struct bpf_map *)ptr)->id; 146 } 147