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