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