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 CLASS(fd, f)(inner_map_ufd); 15 16 inner_map = __bpf_map_get(f); 17 if (IS_ERR(inner_map)) 18 return inner_map; 19 20 /* Does not support >1 level map-in-map */ 21 if (inner_map->inner_map_meta) 22 return ERR_PTR(-EINVAL); 23 if (inner_map->excl_prog_sha) 24 return ERR_PTR(-ENOTSUPP); 25 if (!inner_map->ops->map_meta_equal) 26 return ERR_PTR(-ENOTSUPP); 27 28 inner_map_meta_size = sizeof(*inner_map_meta); 29 /* In some cases verifier needs to access beyond just base map. */ 30 if (inner_map->ops == &array_map_ops || inner_map->ops == &percpu_array_map_ops) 31 inner_map_meta_size = sizeof(struct bpf_array); 32 33 inner_map_meta = kzalloc(inner_map_meta_size, GFP_USER); 34 if (!inner_map_meta) 35 return ERR_PTR(-ENOMEM); 36 37 inner_map_meta->map_type = inner_map->map_type; 38 inner_map_meta->key_size = inner_map->key_size; 39 inner_map_meta->value_size = inner_map->value_size; 40 inner_map_meta->map_flags = inner_map->map_flags; 41 inner_map_meta->max_entries = inner_map->max_entries; 42 43 inner_map_meta->record = btf_record_dup(inner_map->record); 44 if (IS_ERR(inner_map_meta->record)) { 45 /* btf_record_dup returns NULL or valid pointer in case of 46 * invalid/empty/valid, but ERR_PTR in case of errors. During 47 * equality NULL or IS_ERR is equivalent. 48 */ 49 struct bpf_map *ret = ERR_CAST(inner_map_meta->record); 50 kfree(inner_map_meta); 51 return ret; 52 } 53 /* Note: We must use the same BTF, as we also used btf_record_dup above 54 * which relies on BTF being same for both maps, as some members like 55 * record->fields.list_head have pointers like value_rec pointing into 56 * inner_map->btf. 57 */ 58 if (inner_map->btf) { 59 btf_get(inner_map->btf); 60 inner_map_meta->btf = inner_map->btf; 61 } 62 63 /* Misc members not needed in bpf_map_meta_equal() check. */ 64 inner_map_meta->ops = inner_map->ops; 65 if (inner_map->ops == &array_map_ops || inner_map->ops == &percpu_array_map_ops) { 66 struct bpf_array *inner_array_meta = 67 container_of(inner_map_meta, struct bpf_array, map); 68 struct bpf_array *inner_array = container_of(inner_map, struct bpf_array, map); 69 70 inner_array_meta->index_mask = inner_array->index_mask; 71 inner_array_meta->elem_size = inner_array->elem_size; 72 inner_map_meta->bypass_spec_v1 = inner_map->bypass_spec_v1; 73 } 74 return inner_map_meta; 75 } 76 77 void bpf_map_meta_free(struct bpf_map *map_meta) 78 { 79 bpf_map_free_record(map_meta); 80 btf_put(map_meta->btf); 81 kfree(map_meta); 82 } 83 84 bool bpf_map_meta_equal(const struct bpf_map *meta0, 85 const struct bpf_map *meta1) 86 { 87 /* No need to compare ops because it is covered by map_type */ 88 return meta0->map_type == meta1->map_type && 89 meta0->key_size == meta1->key_size && 90 meta0->value_size == meta1->value_size && 91 meta0->map_flags == meta1->map_flags && 92 btf_record_equal(meta0->record, meta1->record); 93 } 94 95 void *bpf_map_fd_get_ptr(struct bpf_map *map, 96 struct file *map_file /* not used */, 97 int ufd) 98 { 99 struct bpf_map *inner_map, *inner_map_meta; 100 CLASS(fd, f)(ufd); 101 102 inner_map = __bpf_map_get(f); 103 if (IS_ERR(inner_map)) 104 return inner_map; 105 if (inner_map->excl_prog_sha) 106 return ERR_PTR(-ENOTSUPP); 107 108 inner_map_meta = map->inner_map_meta; 109 if (inner_map_meta->ops->map_meta_equal(inner_map_meta, inner_map)) 110 bpf_map_inc(inner_map); 111 else 112 inner_map = ERR_PTR(-EINVAL); 113 114 return inner_map; 115 } 116 117 void bpf_map_fd_put_ptr(struct bpf_map *map, void *ptr, bool need_defer) 118 { 119 struct bpf_map *inner_map = ptr; 120 121 /* Defer the freeing of inner map according to the sleepable attribute 122 * of bpf program which owns the outer map, so unnecessary waiting for 123 * RCU tasks trace grace period can be avoided. 124 */ 125 if (need_defer) { 126 if (atomic64_read(&map->sleepable_refcnt)) 127 WRITE_ONCE(inner_map->free_after_mult_rcu_gp, true); 128 else 129 WRITE_ONCE(inner_map->free_after_rcu_gp, true); 130 } 131 bpf_map_put(inner_map); 132 } 133 134 u32 bpf_map_fd_sys_lookup_elem(void *ptr) 135 { 136 return ((struct bpf_map *)ptr)->id; 137 } 138