kernel/bpf/map_in_map.c

   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
  16         f = fdget(inner_map_ufd);
  17         inner_map = __bpf_map_get(f);
  18         if (IS_ERR(inner_map))
  19                 return inner_map;
  20
  21         /* Does not support >1 level map-in-map */
  22         if (inner_map->inner_map_meta) {
  23                 fdput(f);
  24                 return ERR_PTR(-EINVAL);
  25         }
  26
  27         if (!inner_map->ops->map_meta_equal) {
  28                 fdput(f);
  29                 return ERR_PTR(-ENOTSUPP);
  30         }
  31
  32         if (map_value_has_spin_lock(inner_map)) {
  33                 fdput(f);
  34                 return ERR_PTR(-ENOTSUPP);
  35         }
  36
  37         inner_map_meta_size = sizeof(*inner_map_meta);
  38         /* In some cases verifier needs to access beyond just base map. */
  39         if (inner_map->ops == &array_map_ops)
  40                 inner_map_meta_size = sizeof(struct bpf_array);
  41
  42         inner_map_meta = kzalloc(inner_map_meta_size, GFP_USER);
  43         if (!inner_map_meta) {
  44                 fdput(f);
  45                 return ERR_PTR(-ENOMEM);
  46         }
  47
  48         inner_map_meta->map_type = inner_map->map_type;
  49         inner_map_meta->key_size = inner_map->key_size;
  50         inner_map_meta->value_size = inner_map->value_size;
  51         inner_map_meta->map_flags = inner_map->map_flags;
  52         inner_map_meta->max_entries = inner_map->max_entries;
  53         inner_map_meta->spin_lock_off = inner_map->spin_lock_off;
  54         inner_map_meta->timer_off = inner_map->timer_off;
  55         if (inner_map->btf) {
  56                 btf_get(inner_map->btf);
  57                 inner_map_meta->btf = inner_map->btf;
  58         }
  59
  60         /* Misc members not needed in bpf_map_meta_equal() check. */
  61         inner_map_meta->ops = inner_map->ops;
  62         if (inner_map->ops == &array_map_ops) {
  63                 inner_map_meta->bypass_spec_v1 = inner_map->bypass_spec_v1;
  64                 container_of(inner_map_meta, struct bpf_array, map)->index_mask =
  65                      container_of(inner_map, struct bpf_array, map)->index_mask;
  66         }
  67
  68         fdput(f);
  69         return inner_map_meta;
  70 }
  71
  72 void bpf_map_meta_free(struct bpf_map *map_meta)
  73 {
  74         btf_put(map_meta->btf);
  75         kfree(map_meta);
  76 }
  77
  78 bool bpf_map_meta_equal(const struct bpf_map *meta0,
  79                         const struct bpf_map *meta1)
  80 {
  81         /* No need to compare ops because it is covered by map_type */
  82         return meta0->map_type == meta1->map_type &&
  83                 meta0->key_size == meta1->key_size &&
  84                 meta0->value_size == meta1->value_size &&
  85                 meta0->timer_off == meta1->timer_off &&
  86                 meta0->map_flags == meta1->map_flags;
  87 }
  88
  89 void *bpf_map_fd_get_ptr(struct bpf_map *map,
  90                          struct file *map_file /* not used */,
  91                          int ufd)
  92 {
  93         struct bpf_map *inner_map, *inner_map_meta;
  94         struct fd f;
  95
  96         f = fdget(ufd);
  97         inner_map = __bpf_map_get(f);
  98         if (IS_ERR(inner_map))
  99                 return inner_map;
 100
 101         inner_map_meta = map->inner_map_meta;
 102         if (inner_map_meta->ops->map_meta_equal(inner_map_meta, inner_map))
 103                 bpf_map_inc(inner_map);
 104         else
 105                 inner_map = ERR_PTR(-EINVAL);
 106
 107         fdput(f);
 108         return inner_map;
 109 }
 110
 111 void bpf_map_fd_put_ptr(void *ptr)
 112 {
 113         /* ptr->ops->map_free() has to go through one
 114          * rcu grace period by itself.
 115          */
 116         bpf_map_put(ptr);
 117 }
 118
 119 u32 bpf_map_fd_sys_lookup_elem(void *ptr)
 120 {
 121         return ((struct bpf_map *)ptr)->id;
 122 }