kernel/bpf/map_in_map.c

   1 /* Copyright (c) 2017 Facebook
   2  *
   3  * This program is free software; you can redistribute it and/or
   4  * modify it under the terms of version 2 of the GNU General Public
   5  * License as published by the Free Software Foundation.
   6  */
   7 #include <linux/slab.h>
   8 #include <linux/bpf.h>
   9
  10 #include "map_in_map.h"
  11
  12 struct bpf_map *bpf_map_meta_alloc(int inner_map_ufd)
  13 {
  14         struct bpf_map *inner_map, *inner_map_meta;
  15         struct fd f;
  16
  17         f = fdget(inner_map_ufd);
  18         inner_map = __bpf_map_get(f);
  19         if (IS_ERR(inner_map))
  20                 return inner_map;
  21
  22         /* prog_array->owner_prog_type and owner_jited
  23          * is a runtime binding.  Doing static check alone
  24          * in the verifier is not enough.
  25          */
  26         if (inner_map->map_type == BPF_MAP_TYPE_PROG_ARRAY ||
  27             inner_map->map_type == BPF_MAP_TYPE_CGROUP_STORAGE) {
  28                 fdput(f);
  29                 return ERR_PTR(-ENOTSUPP);
  30         }
  31
  32         /* Does not support >1 level map-in-map */
  33         if (inner_map->inner_map_meta) {
  34                 fdput(f);
  35                 return ERR_PTR(-EINVAL);
  36         }
  37
  38         inner_map_meta = kzalloc(sizeof(*inner_map_meta), GFP_USER);
  39         if (!inner_map_meta) {
  40                 fdput(f);
  41                 return ERR_PTR(-ENOMEM);
  42         }
  43
  44         inner_map_meta->map_type = inner_map->map_type;
  45         inner_map_meta->key_size = inner_map->key_size;
  46         inner_map_meta->value_size = inner_map->value_size;
  47         inner_map_meta->map_flags = inner_map->map_flags;
  48         inner_map_meta->ops = inner_map->ops;
  49         inner_map_meta->max_entries = inner_map->max_entries;
  50
  51         fdput(f);
  52         return inner_map_meta;
  53 }
  54
  55 void bpf_map_meta_free(struct bpf_map *map_meta)
  56 {
  57         kfree(map_meta);
  58 }
  59
  60 bool bpf_map_meta_equal(const struct bpf_map *meta0,
  61                         const struct bpf_map *meta1)
  62 {
  63         /* No need to compare ops because it is covered by map_type */
  64         return meta0->map_type == meta1->map_type &&
  65                 meta0->key_size == meta1->key_size &&
  66                 meta0->value_size == meta1->value_size &&
  67                 meta0->map_flags == meta1->map_flags &&
  68                 meta0->max_entries == meta1->max_entries;
  69 }
  70
  71 void *bpf_map_fd_get_ptr(struct bpf_map *map,
  72                          struct file *map_file /* not used */,
  73                          int ufd)
  74 {
  75         struct bpf_map *inner_map;
  76         struct fd f;
  77
  78         f = fdget(ufd);
  79         inner_map = __bpf_map_get(f);
  80         if (IS_ERR(inner_map))
  81                 return inner_map;
  82
  83         if (bpf_map_meta_equal(map->inner_map_meta, inner_map))
  84                 inner_map = bpf_map_inc(inner_map, false);
  85         else
  86                 inner_map = ERR_PTR(-EINVAL);
  87
  88         fdput(f);
  89         return inner_map;
  90 }
  91
  92 void bpf_map_fd_put_ptr(void *ptr)
  93 {
  94         /* ptr->ops->map_free() has to go through one
  95          * rcu grace period by itself.
  96          */
  97         bpf_map_put(ptr);
  98 }
  99
 100 u32 bpf_map_fd_sys_lookup_elem(void *ptr)
 101 {
 102         return ((struct bpf_map *)ptr)->id;
 103 }