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 12 struct bpf_map *bpf_map_meta_alloc(int inner_map_ufd) 13 { 14 struct bpf_map *inner_map, *inner_map_meta; 15 struct fd f; 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 /* prog_array->owner_prog_type and owner_jited 23 * is a runtime binding. Doing static check alone 24 * in the verifier is not enough. 25 */ 26 if (inner_map->map_type == BPF_MAP_TYPE_PROG_ARRAY) { 27 fdput(f); 28 return ERR_PTR(-ENOTSUPP); 29 } 30 31 /* Does not support >1 level map-in-map */ 32 if (inner_map->inner_map_meta) { 33 fdput(f); 34 return ERR_PTR(-EINVAL); 35 } 36 37 inner_map_meta = kzalloc(sizeof(*inner_map_meta), GFP_USER); 38 if (!inner_map_meta) { 39 fdput(f); 40 return ERR_PTR(-ENOMEM); 41 } 42 43 inner_map_meta->map_type = inner_map->map_type; 44 inner_map_meta->key_size = inner_map->key_size; 45 inner_map_meta->value_size = inner_map->value_size; 46 inner_map_meta->map_flags = inner_map->map_flags; 47 inner_map_meta->ops = inner_map->ops; 48 inner_map_meta->max_entries = inner_map->max_entries; 49 50 fdput(f); 51 return inner_map_meta; 52 } 53 54 void bpf_map_meta_free(struct bpf_map *map_meta) 55 { 56 kfree(map_meta); 57 } 58 59 bool bpf_map_meta_equal(const struct bpf_map *meta0, 60 const struct bpf_map *meta1) 61 { 62 /* No need to compare ops because it is covered by map_type */ 63 return meta0->map_type == meta1->map_type && 64 meta0->key_size == meta1->key_size && 65 meta0->value_size == meta1->value_size && 66 meta0->map_flags == meta1->map_flags && 67 meta0->max_entries == meta1->max_entries; 68 } 69 70 void *bpf_map_fd_get_ptr(struct bpf_map *map, 71 struct file *map_file /* not used */, 72 int ufd) 73 { 74 struct bpf_map *inner_map; 75 struct fd f; 76 77 f = fdget(ufd); 78 inner_map = __bpf_map_get(f); 79 if (IS_ERR(inner_map)) 80 return inner_map; 81 82 if (bpf_map_meta_equal(map->inner_map_meta, inner_map)) 83 inner_map = bpf_map_inc(inner_map, false); 84 else 85 inner_map = ERR_PTR(-EINVAL); 86 87 fdput(f); 88 return inner_map; 89 } 90 91 void bpf_map_fd_put_ptr(void *ptr) 92 { 93 /* ptr->ops->map_free() has to go through one 94 * rcu grace period by itself. 95 */ 96 bpf_map_put(ptr); 97 } 98