/* Copyright (c) 2017 Facebook
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of version 2 of the GNU General Public
   * License as published by the Free Software Foundation.
   */
  #include <linux/slab.h>
  #include <linux/bpf.h>
  
  #include "map_in_map.h"
  
  struct bpf_map *bpf_map_meta_alloc(int inner_map_ufd)
  {
  	struct bpf_map *inner_map, *inner_map_meta;
  	struct fd f;
  
  	f = fdget(inner_map_ufd);
  	inner_map = __bpf_map_get(f);
  	if (IS_ERR(inner_map))
  		return inner_map;
  
  	/* prog_array->owner_prog_type and owner_jited
  	 * is a runtime binding.  Doing static check alone
  	 * in the verifier is not enough.
  	 */
  	if (inner_map->map_type == BPF_MAP_TYPE_PROG_ARRAY) {
  		fdput(f);
  		return ERR_PTR(-ENOTSUPP);
  	}
  
  	/* Does not support >1 level map-in-map */
  	if (inner_map->inner_map_meta) {
  		fdput(f);
  		return ERR_PTR(-EINVAL);
  	}
  
  	inner_map_meta = kzalloc(sizeof(*inner_map_meta), GFP_USER);
  	if (!inner_map_meta) {
  		fdput(f);
  		return ERR_PTR(-ENOMEM);
  	}
  
  	inner_map_meta->map_type = inner_map->map_type;
  	inner_map_meta->key_size = inner_map->key_size;
  	inner_map_meta->value_size = inner_map->value_size;
  	inner_map_meta->map_flags = inner_map->map_flags;
  	inner_map_meta->ops = inner_map->ops;
  	inner_map_meta->max_entries = inner_map->max_entries;
  
  	fdput(f);
  	return inner_map_meta;
  }
  
  void bpf_map_meta_free(struct bpf_map *map_meta)
  {
  	kfree(map_meta);
  }
  
  bool bpf_map_meta_equal(const struct bpf_map *meta0,
  			const struct bpf_map *meta1)
  {
  	/* No need to compare ops because it is covered by map_type */
  	return meta0->map_type == meta1->map_type &&
  		meta0->key_size == meta1->key_size &&
  		meta0->value_size == meta1->value_size &&
  		meta0->map_flags == meta1->map_flags &&
  		meta0->max_entries == meta1->max_entries;
  }
  
  void *bpf_map_fd_get_ptr(struct bpf_map *map,
  			 struct file *map_file /* not used */,
  			 int ufd)
  {
  	struct bpf_map *inner_map;
  	struct fd f;
  
  	f = fdget(ufd);
  	inner_map = __bpf_map_get(f);
  	if (IS_ERR(inner_map))
  		return inner_map;
  
  	if (bpf_map_meta_equal(map->inner_map_meta, inner_map))
  		inner_map = bpf_map_inc(inner_map, false);
  	else
  		inner_map = ERR_PTR(-EINVAL);
  
  	fdput(f);
  	return inner_map;
  }
  
  void bpf_map_fd_put_ptr(void *ptr)
  {
  	/* ptr->ops->map_free() has to go through one
  	 * rcu grace period by itself.
  	 */
  	bpf_map_put(ptr);
  }

  
  u32 bpf_map_fd_sys_lookup_elem(void *ptr)
  {
  	return ((struct bpf_map *)ptr)->id;
  }