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->owner_prog_type and owner_jited
  21          * is a runtime binding.  Doing static check alone
  22          * in the verifier is not enough.
  23          */
  24         if (inner_map->map_type == BPF_MAP_TYPE_PROG_ARRAY ||
  25             inner_map->map_type == BPF_MAP_TYPE_CGROUP_STORAGE ||
  26             inner_map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE) {
  27                 fdput(f);
  28                 return ERR_PTR(-ENOTSUPP);
  29         }
  30
  31         /* Does not support >1 level map-in-map */
  32         if (inner_map->inner_map_meta) {
  33                 fdput(f);
  34                 return ERR_PTR(-EINVAL);
  35         }
  36
  37         if (map_value_has_spin_lock(inner_map)) {
  38                 fdput(f);
  39                 return ERR_PTR(-ENOTSUPP);
  40         }
  41
  42         inner_map_meta_size = sizeof(*inner_map_meta);
  43         /* In some cases verifier needs to access beyond just base map. */
  44         if (inner_map->ops == &array_map_ops)
  45                 inner_map_meta_size = sizeof(struct bpf_array);
  46
  47         inner_map_meta = kzalloc(inner_map_meta_size, GFP_USER);
  48         if (!inner_map_meta) {
  49                 fdput(f);
  50                 return ERR_PTR(-ENOMEM);
  51         }
  52
  53         inner_map_meta->map_type = inner_map->map_type;
  54         inner_map_meta->key_size = inner_map->key_size;
  55         inner_map_meta->value_size = inner_map->value_size;
  56         inner_map_meta->map_flags = inner_map->map_flags;
  57         inner_map_meta->max_entries = inner_map->max_entries;
  58         inner_map_meta->spin_lock_off = inner_map->spin_lock_off;
  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->unpriv_array = inner_map->unpriv_array;
  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         kfree(map_meta);
  75 }
  76
  77 bool bpf_map_meta_equal(const struct bpf_map *meta0,
  78                         const struct bpf_map *meta1)
  79 {
  80         /* No need to compare ops because it is covered by map_type */
  81         return meta0->map_type == meta1->map_type &&
  82                 meta0->key_size == meta1->key_size &&
  83                 meta0->value_size == meta1->value_size &&
  84                 meta0->map_flags == meta1->map_flags &&
  85                 meta0->max_entries == meta1->max_entries;
  86 }
  87
  88 void *bpf_map_fd_get_ptr(struct bpf_map *map,
  89                          struct file *map_file /* not used */,
  90                          int ufd)
  91 {
  92         struct bpf_map *inner_map;
  93         struct fd f;
  94
  95         f = fdget(ufd);
  96         inner_map = __bpf_map_get(f);
  97         if (IS_ERR(inner_map))
  98                 return inner_map;
  99
 100         if (bpf_map_meta_equal(map->inner_map_meta, inner_map))
 101                 inner_map = bpf_map_inc(inner_map, false);
 102         else
 103                 inner_map = ERR_PTR(-EINVAL);
 104
 105         fdput(f);
 106         return inner_map;
 107 }
 108
 109 void bpf_map_fd_put_ptr(void *ptr)
 110 {
 111         /* ptr->ops->map_free() has to go through one
 112          * rcu grace period by itself.
 113          */
 114         bpf_map_put(ptr);
 115 }
 116
 117 u32 bpf_map_fd_sys_lookup_elem(void *ptr)
 118 {
 119         return ((struct bpf_map *)ptr)->id;
 120 }