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