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
   7 #include "map_in_map.h"
   8
   9 struct bpf_map *bpf_map_meta_alloc(int inner_map_ufd)
  10 {
  11         struct bpf_map *inner_map, *inner_map_meta;
  12         u32 inner_map_meta_size;
  13         struct fd f;
  14
  15         f = fdget(inner_map_ufd);
  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                 fdput(f);
  23                 return ERR_PTR(-EINVAL);
  24         }
  25
  26         if (!inner_map->ops->map_meta_equal) {
  27                 fdput(f);
  28                 return ERR_PTR(-ENOTSUPP);
  29         }
  30
  31         if (map_value_has_spin_lock(inner_map)) {
  32                 fdput(f);
  33                 return ERR_PTR(-ENOTSUPP);
  34         }
  35
  36         inner_map_meta_size = sizeof(*inner_map_meta);
  37         /* In some cases verifier needs to access beyond just base map. */
  38         if (inner_map->ops == &array_map_ops)
  39                 inner_map_meta_size = sizeof(struct bpf_array);
  40
  41         inner_map_meta = kzalloc(inner_map_meta_size, GFP_USER);
  42         if (!inner_map_meta) {
  43                 fdput(f);
  44                 return ERR_PTR(-ENOMEM);
  45         }
  46
  47         inner_map_meta->map_type = inner_map->map_type;
  48         inner_map_meta->key_size = inner_map->key_size;
  49         inner_map_meta->value_size = inner_map->value_size;
  50         inner_map_meta->map_flags = inner_map->map_flags;
  51         inner_map_meta->max_entries = inner_map->max_entries;
  52         inner_map_meta->spin_lock_off = inner_map->spin_lock_off;
  53
  54         /* Misc members not needed in bpf_map_meta_equal() check. */
  55         inner_map_meta->ops = inner_map->ops;
  56         if (inner_map->ops == &array_map_ops) {
  57                 inner_map_meta->bypass_spec_v1 = inner_map->bypass_spec_v1;
  58                 container_of(inner_map_meta, struct bpf_array, map)->index_mask =
  59                      container_of(inner_map, struct bpf_array, map)->index_mask;
  60         }
  61
  62         fdput(f);
  63         return inner_map_meta;
  64 }
  65
  66 void bpf_map_meta_free(struct bpf_map *map_meta)
  67 {
  68         kfree(map_meta);
  69 }
  70
  71 bool bpf_map_meta_equal(const struct bpf_map *meta0,
  72                         const struct bpf_map *meta1)
  73 {
  74         /* No need to compare ops because it is covered by map_type */
  75         return meta0->map_type == meta1->map_type &&
  76                 meta0->key_size == meta1->key_size &&
  77                 meta0->value_size == meta1->value_size &&
  78                 meta0->map_flags == meta1->map_flags;
  79 }
  80
  81 void *bpf_map_fd_get_ptr(struct bpf_map *map,
  82                          struct file *map_file /* not used */,
  83                          int ufd)
  84 {
  85         struct bpf_map *inner_map, *inner_map_meta;
  86         struct fd f;
  87
  88         f = fdget(ufd);
  89         inner_map = __bpf_map_get(f);
  90         if (IS_ERR(inner_map))
  91                 return inner_map;
  92
  93         inner_map_meta = map->inner_map_meta;
  94         if (inner_map_meta->ops->map_meta_equal(inner_map_meta, inner_map))
  95                 bpf_map_inc(inner_map);
  96         else
  97                 inner_map = ERR_PTR(-EINVAL);
  98
  99         fdput(f);
 100         return inner_map;
 101 }
 102
 103 void bpf_map_fd_put_ptr(void *ptr)
 104 {
 105         /* ptr->ops->map_free() has to go through one
 106          * rcu grace period by itself.
 107          */
 108         bpf_map_put(ptr);
 109 }
 110
 111 u32 bpf_map_fd_sys_lookup_elem(void *ptr)
 112 {
 113         return ((struct bpf_map *)ptr)->id;
 114 }