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                 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         inner_map_meta = kzalloc(sizeof(*inner_map_meta), GFP_USER);
  38         if (!inner_map_meta) {
  39                 fdput(f);
  40                 return ERR_PTR(-ENOMEM);
  41         }
  42
  43         inner_map_meta->map_type = inner_map->map_type;
  44         inner_map_meta->key_size = inner_map->key_size;
  45         inner_map_meta->value_size = inner_map->value_size;
  46         inner_map_meta->map_flags = inner_map->map_flags;
  47         inner_map_meta->ops = inner_map->ops;
  48         inner_map_meta->max_entries = inner_map->max_entries;
  49
  50         fdput(f);
  51         return inner_map_meta;
  52 }
  53
  54 void bpf_map_meta_free(struct bpf_map *map_meta)
  55 {
  56         kfree(map_meta);
  57 }
  58
  59 bool bpf_map_meta_equal(const struct bpf_map *meta0,
  60                         const struct bpf_map *meta1)
  61 {
  62         /* No need to compare ops because it is covered by map_type */
  63         return meta0->map_type == meta1->map_type &&
  64                 meta0->key_size == meta1->key_size &&
  65                 meta0->value_size == meta1->value_size &&
  66                 meta0->map_flags == meta1->map_flags &&
  67                 meta0->max_entries == meta1->max_entries;
  68 }
  69
  70 void *bpf_map_fd_get_ptr(struct bpf_map *map,
  71                          struct file *map_file /* not used */,
  72                          int ufd)
  73 {
  74         struct bpf_map *inner_map;
  75         struct fd f;
  76
  77         f = fdget(ufd);
  78         inner_map = __bpf_map_get(f);
  79         if (IS_ERR(inner_map))
  80                 return inner_map;
  81
  82         if (bpf_map_meta_equal(map->inner_map_meta, inner_map))
  83                 inner_map = bpf_map_inc(inner_map, false);
  84         else
  85                 inner_map = ERR_PTR(-EINVAL);
  86
  87         fdput(f);
  88         return inner_map;
  89 }
  90
  91 void bpf_map_fd_put_ptr(void *ptr)
  92 {
  93         /* ptr->ops->map_free() has to go through one
  94          * rcu grace period by itself.
  95          */
  96         bpf_map_put(ptr);
  97 }
  98
  99 u32 bpf_map_fd_sys_lookup_elem(void *ptr)
 100 {
 101         return ((struct bpf_map *)ptr)->id;
 102 }