/*

   * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>

   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * Development of this code funded by Astaro AG (http://www.astaro.com/)
   */
  
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/list.h>

  #include <linux/log2.h>

  #include <linux/jhash.h>
  #include <linux/netlink.h>

  #include <linux/workqueue.h>

  #include <linux/rhashtable.h>

  #include <linux/netfilter.h>
  #include <linux/netfilter/nf_tables.h>
  #include <net/netfilter/nf_tables.h>

  /* We target a hash table size of 4, element hint is 75% of final size */

  #define NFT_RHASH_ELEMENT_HINT 3

  struct nft_rhash {

  	struct rhashtable		ht;

  	struct delayed_work		gc_work;

  };

  struct nft_rhash_elem {

  	struct rhash_head		node;

  	struct nft_set_ext		ext;

  };

  struct nft_rhash_cmp_arg {

  	const struct nft_set		*set;

  	const u32			*key;

  	u8				genmask;

  };

  static inline u32 nft_rhash_key(const void *data, u32 len, u32 seed)

  {

  	const struct nft_rhash_cmp_arg *arg = data;

  
  	return jhash(arg->key, len, seed);
  }

  static inline u32 nft_rhash_obj(const void *data, u32 len, u32 seed)

  {

  	const struct nft_rhash_elem *he = data;

  	return jhash(nft_set_ext_key(&he->ext), len, seed);

  }

  static inline int nft_rhash_cmp(struct rhashtable_compare_arg *arg,
  				const void *ptr)

  {

  	const struct nft_rhash_cmp_arg *x = arg->key;
  	const struct nft_rhash_elem *he = ptr;

  	if (memcmp(nft_set_ext_key(&he->ext), x->key, x->set->klen))

  		return 1;

  	if (nft_set_elem_expired(&he->ext))
  		return 1;

  	if (!nft_set_elem_active(&he->ext, x->genmask))
  		return 1;

  	return 0;
  }

  static const struct rhashtable_params nft_rhash_params = {
  	.head_offset		= offsetof(struct nft_rhash_elem, node),
  	.hashfn			= nft_rhash_key,
  	.obj_hashfn		= nft_rhash_obj,
  	.obj_cmpfn		= nft_rhash_cmp,

  	.automatic_shrinking	= true,
  };

  static bool nft_rhash_lookup(const struct net *net, const struct nft_set *set,
  			     const u32 *key, const struct nft_set_ext **ext)

  {

  	struct nft_rhash *priv = nft_set_priv(set);
  	const struct nft_rhash_elem *he;
  	struct nft_rhash_cmp_arg arg = {

  		.genmask = nft_genmask_cur(net),

  		.set	 = set,
  		.key	 = key,
  	};

  	he = rhashtable_lookup_fast(&priv->ht, &arg, nft_rhash_params);

  	if (he != NULL)
  		*ext = &he->ext;

  	return !!he;

  }

  static bool nft_rhash_update(struct nft_set *set, const u32 *key,
  			     void *(*new)(struct nft_set *,
  					  const struct nft_expr *,
  					  struct nft_regs *regs),
  			     const struct nft_expr *expr,
  			     struct nft_regs *regs,
  			     const struct nft_set_ext **ext)

  {

  	struct nft_rhash *priv = nft_set_priv(set);
  	struct nft_rhash_elem *he, *prev;
  	struct nft_rhash_cmp_arg arg = {

  		.genmask = NFT_GENMASK_ANY,
  		.set	 = set,
  		.key	 = key,
  	};

  	he = rhashtable_lookup_fast(&priv->ht, &arg, nft_rhash_params);

  	if (he != NULL)
  		goto out;

  	he = new(set, expr, regs);

  	if (he == NULL)
  		goto err1;

  
  	prev = rhashtable_lookup_get_insert_key(&priv->ht, &arg, &he->node,

  						nft_rhash_params);

  	if (IS_ERR(prev))

  		goto err2;

  
  	/* Another cpu may race to insert the element with the same key */
  	if (prev) {
  		nft_set_elem_destroy(set, he, true);
  		he = prev;
  	}

  out:
  	*ext = &he->ext;
  	return true;
  
  err2:

  	nft_set_elem_destroy(set, he, true);

  err1:
  	return false;
  }

  static int nft_rhash_insert(const struct net *net, const struct nft_set *set,
  			    const struct nft_set_elem *elem,
  			    struct nft_set_ext **ext)

  {

  	struct nft_rhash *priv = nft_set_priv(set);
  	struct nft_rhash_elem *he = elem->priv;
  	struct nft_rhash_cmp_arg arg = {

  		.genmask = nft_genmask_next(net),

  		.set	 = set,

  		.key	 = elem->key.val.data,

  	};

  	struct nft_rhash_elem *prev;

  
  	prev = rhashtable_lookup_get_insert_key(&priv->ht, &arg, &he->node,

  						nft_rhash_params);

  	if (IS_ERR(prev))
  		return PTR_ERR(prev);
  	if (prev) {
  		*ext = &prev->ext;
  		return -EEXIST;
  	}
  	return 0;

  }

  static void nft_rhash_activate(const struct net *net, const struct nft_set *set,
  			       const struct nft_set_elem *elem)

  {

  	struct nft_rhash_elem *he = elem->priv;

  	nft_set_elem_change_active(net, set, &he->ext);

  	nft_set_elem_clear_busy(&he->ext);

  }

  static bool nft_rhash_flush(const struct net *net,
  			    const struct nft_set *set, void *priv)

  {

  	struct nft_rhash_elem *he = priv;

  
  	if (!nft_set_elem_mark_busy(&he->ext) ||
  	    !nft_is_active(net, &he->ext)) {
  		nft_set_elem_change_active(net, set, &he->ext);
  		return true;
  	}
  	return false;
  }

  static void *nft_rhash_deactivate(const struct net *net,
  				  const struct nft_set *set,
  				  const struct nft_set_elem *elem)

  {

  	struct nft_rhash *priv = nft_set_priv(set);
  	struct nft_rhash_elem *he;
  	struct nft_rhash_cmp_arg arg = {

  		.genmask = nft_genmask_next(net),

  		.set	 = set,

  		.key	 = elem->key.val.data,

  	};

  	rcu_read_lock();

  	he = rhashtable_lookup_fast(&priv->ht, &arg, nft_rhash_params);

  	if (he != NULL &&

  	    !nft_rhash_flush(net, set, he))

  		he = NULL;

  	rcu_read_unlock();

  	return he;
  }

  static void nft_rhash_remove(const struct net *net,
  			     const struct nft_set *set,
  			     const struct nft_set_elem *elem)

  {

  	struct nft_rhash *priv = nft_set_priv(set);
  	struct nft_rhash_elem *he = elem->priv;

  	rhashtable_remove_fast(&priv->ht, &he->node, nft_rhash_params);

  }

  static void nft_rhash_walk(const struct nft_ctx *ctx, struct nft_set *set,
  			   struct nft_set_iter *iter)

  {

  	struct nft_rhash *priv = nft_set_priv(set);
  	struct nft_rhash_elem *he;

  	struct rhashtable_iter hti;

  	struct nft_set_elem elem;

  	int err;

  	err = rhashtable_walk_init(&priv->ht, &hti, GFP_ATOMIC);

  	iter->err = err;
  	if (err)
  		return;

  	err = rhashtable_walk_start(&hti);
  	if (err && err != -EAGAIN) {
  		iter->err = err;
  		goto out;
  	}
  
  	while ((he = rhashtable_walk_next(&hti))) {
  		if (IS_ERR(he)) {
  			err = PTR_ERR(he);
  			if (err != -EAGAIN) {
  				iter->err = err;
  				goto out;
  			}

  
  			continue;

  		}
  
  		if (iter->count < iter->skip)
  			goto cont;

  		if (nft_set_elem_expired(&he->ext))
  			goto cont;

  		if (!nft_set_elem_active(&he->ext, iter->genmask))

  			goto cont;

  		elem.priv = he;

  
  		iter->err = iter->fn(ctx, set, iter, &elem);
  		if (iter->err < 0)
  			goto out;

  cont:

  		iter->count++;

  	}

  
  out:
  	rhashtable_walk_stop(&hti);
  	rhashtable_walk_exit(&hti);

  }

  static void nft_rhash_gc(struct work_struct *work)

  {

  	struct nft_set *set;

  	struct nft_rhash_elem *he;
  	struct nft_rhash *priv;

  	struct nft_set_gc_batch *gcb = NULL;
  	struct rhashtable_iter hti;
  	int err;

  	priv = container_of(work, struct nft_rhash, gc_work.work);

  	set  = nft_set_container_of(priv);

  	err = rhashtable_walk_init(&priv->ht, &hti, GFP_KERNEL);

  	if (err)
  		goto schedule;
  
  	err = rhashtable_walk_start(&hti);
  	if (err && err != -EAGAIN)
  		goto out;
  
  	while ((he = rhashtable_walk_next(&hti))) {
  		if (IS_ERR(he)) {
  			if (PTR_ERR(he) != -EAGAIN)
  				goto out;
  			continue;
  		}
  
  		if (!nft_set_elem_expired(&he->ext))
  			continue;
  		if (nft_set_elem_mark_busy(&he->ext))
  			continue;
  
  		gcb = nft_set_gc_batch_check(set, gcb, GFP_ATOMIC);
  		if (gcb == NULL)
  			goto out;

  		rhashtable_remove_fast(&priv->ht, &he->node, nft_rhash_params);

  		atomic_dec(&set->nelems);

  		nft_set_gc_batch_add(gcb, he);
  	}
  out:
  	rhashtable_walk_stop(&hti);
  	rhashtable_walk_exit(&hti);
  
  	nft_set_gc_batch_complete(gcb);
  schedule:
  	queue_delayed_work(system_power_efficient_wq, &priv->gc_work,
  			   nft_set_gc_interval(set));
  }

  static unsigned int nft_rhash_privsize(const struct nlattr * const nla[],
  				       const struct nft_set_desc *desc)

  {

  	return sizeof(struct nft_rhash);

  }

  static int nft_rhash_init(const struct nft_set *set,
  			  const struct nft_set_desc *desc,
  			  const struct nlattr * const tb[])

  {

  	struct nft_rhash *priv = nft_set_priv(set);
  	struct rhashtable_params params = nft_rhash_params;

  	int err;

  	params.nelem_hint = desc->size ?: NFT_RHASH_ELEMENT_HINT;

  	params.key_len	  = set->klen;

  	err = rhashtable_init(&priv->ht, &params);
  	if (err < 0)
  		return err;

  	INIT_DEFERRABLE_WORK(&priv->gc_work, nft_rhash_gc);

  	if (set->flags & NFT_SET_TIMEOUT)
  		queue_delayed_work(system_power_efficient_wq, &priv->gc_work,
  				   nft_set_gc_interval(set));
  	return 0;

  }

  static void nft_rhash_elem_destroy(void *ptr, void *arg)

  {

  	nft_set_elem_destroy(arg, ptr, true);

  }

  static void nft_rhash_destroy(const struct nft_set *set)

  {

  	struct nft_rhash *priv = nft_set_priv(set);

  	cancel_delayed_work_sync(&priv->gc_work);

  	rcu_barrier();

  	rhashtable_free_and_destroy(&priv->ht, nft_rhash_elem_destroy,

  				    (void *)set);

  }

  static u32 nft_hash_buckets(u32 size)
  {
  	return roundup_pow_of_two(size * 4 / 3);
  }

  static bool nft_rhash_estimate(const struct nft_set_desc *desc, u32 features,
  			       struct nft_set_estimate *est)

  {

  	est->size   = ~0;
  	est->lookup = NFT_SET_CLASS_O_1;
  	est->space  = NFT_SET_CLASS_O_N;
  
  	return true;
  }
  
  struct nft_hash {
  	u32				seed;
  	u32				buckets;
  	struct hlist_head		table[];
  };
  
  struct nft_hash_elem {
  	struct hlist_node		node;
  	struct nft_set_ext		ext;
  };
  
  static bool nft_hash_lookup(const struct net *net, const struct nft_set *set,
  			    const u32 *key, const struct nft_set_ext **ext)
  {
  	struct nft_hash *priv = nft_set_priv(set);
  	u8 genmask = nft_genmask_cur(net);
  	const struct nft_hash_elem *he;
  	u32 hash;
  
  	hash = jhash(key, set->klen, priv->seed);
  	hash = reciprocal_scale(hash, priv->buckets);
  	hlist_for_each_entry_rcu(he, &priv->table[hash], node) {
  		if (!memcmp(nft_set_ext_key(&he->ext), key, set->klen) &&
  		    nft_set_elem_active(&he->ext, genmask)) {
  			*ext = &he->ext;
  			return true;
  		}
  	}
  	return false;
  }

  /* nft_hash_select_ops() makes sure key size can be either 2 or 4 bytes . */
  static inline u32 nft_hash_key(const u32 *key, u32 klen)
  {
  	if (klen == 4)
  		return *key;
  
  	return *(u16 *)key;
  }
  
  static bool nft_hash_lookup_fast(const struct net *net,
  				 const struct nft_set *set,
  				 const u32 *key, const struct nft_set_ext **ext)
  {
  	struct nft_hash *priv = nft_set_priv(set);
  	u8 genmask = nft_genmask_cur(net);
  	const struct nft_hash_elem *he;
  	u32 hash, k1, k2;
  
  	k1 = nft_hash_key(key, set->klen);
  	hash = jhash_1word(k1, priv->seed);
  	hash = reciprocal_scale(hash, priv->buckets);
  	hlist_for_each_entry_rcu(he, &priv->table[hash], node) {
  		k2 = nft_hash_key(nft_set_ext_key(&he->ext)->data, set->klen);
  		if (k1 == k2 &&
  		    nft_set_elem_active(&he->ext, genmask)) {
  			*ext = &he->ext;
  			return true;
  		}
  	}
  	return false;
  }

  static int nft_hash_insert(const struct net *net, const struct nft_set *set,
  			   const struct nft_set_elem *elem,
  			   struct nft_set_ext **ext)
  {
  	struct nft_hash_elem *this = elem->priv, *he;
  	struct nft_hash *priv = nft_set_priv(set);
  	u8 genmask = nft_genmask_next(net);
  	u32 hash;
  
  	hash = jhash(nft_set_ext_key(&this->ext), set->klen, priv->seed);
  	hash = reciprocal_scale(hash, priv->buckets);
  	hlist_for_each_entry(he, &priv->table[hash], node) {
  		if (!memcmp(nft_set_ext_key(&this->ext),
  			    nft_set_ext_key(&he->ext), set->klen) &&
  		    nft_set_elem_active(&he->ext, genmask)) {
  			*ext = &he->ext;
  			return -EEXIST;
  		}
  	}
  	hlist_add_head_rcu(&this->node, &priv->table[hash]);
  	return 0;
  }
  
  static void nft_hash_activate(const struct net *net, const struct nft_set *set,
  			      const struct nft_set_elem *elem)
  {
  	struct nft_hash_elem *he = elem->priv;
  
  	nft_set_elem_change_active(net, set, &he->ext);
  }
  
  static bool nft_hash_flush(const struct net *net,
  			   const struct nft_set *set, void *priv)
  {
  	struct nft_hash_elem *he = priv;
  
  	nft_set_elem_change_active(net, set, &he->ext);
  	return true;
  }
  
  static void *nft_hash_deactivate(const struct net *net,
  				 const struct nft_set *set,
  				 const struct nft_set_elem *elem)
  {
  	struct nft_hash *priv = nft_set_priv(set);
  	struct nft_hash_elem *this = elem->priv, *he;
  	u8 genmask = nft_genmask_next(net);
  	u32 hash;
  
  	hash = jhash(nft_set_ext_key(&this->ext), set->klen, priv->seed);
  	hash = reciprocal_scale(hash, priv->buckets);
  	hlist_for_each_entry(he, &priv->table[hash], node) {
  		if (!memcmp(nft_set_ext_key(&this->ext), &elem->key.val,
  			    set->klen) ||
  		    nft_set_elem_active(&he->ext, genmask)) {
  			nft_set_elem_change_active(net, set, &he->ext);
  			return he;
  		}
  	}
  	return NULL;
  }
  
  static void nft_hash_remove(const struct net *net,
  			    const struct nft_set *set,
  			    const struct nft_set_elem *elem)
  {
  	struct nft_hash_elem *he = elem->priv;
  
  	hlist_del_rcu(&he->node);
  }
  
  static void nft_hash_walk(const struct nft_ctx *ctx, struct nft_set *set,
  			  struct nft_set_iter *iter)
  {
  	struct nft_hash *priv = nft_set_priv(set);
  	struct nft_hash_elem *he;
  	struct nft_set_elem elem;
  	int i;
  
  	for (i = 0; i < priv->buckets; i++) {
  		hlist_for_each_entry_rcu(he, &priv->table[i], node) {
  			if (iter->count < iter->skip)
  				goto cont;
  			if (!nft_set_elem_active(&he->ext, iter->genmask))
  				goto cont;
  
  			elem.priv = he;
  
  			iter->err = iter->fn(ctx, set, iter, &elem);
  			if (iter->err < 0)
  				return;
  cont:
  			iter->count++;
  		}
  	}
  }
  
  static unsigned int nft_hash_privsize(const struct nlattr * const nla[],
  				      const struct nft_set_desc *desc)
  {
  	return sizeof(struct nft_hash) +
  	       nft_hash_buckets(desc->size) * sizeof(struct hlist_head);
  }
  
  static int nft_hash_init(const struct nft_set *set,
  			 const struct nft_set_desc *desc,
  			 const struct nlattr * const tb[])
  {
  	struct nft_hash *priv = nft_set_priv(set);
  
  	priv->buckets = nft_hash_buckets(desc->size);
  	get_random_bytes(&priv->seed, sizeof(priv->seed));
  
  	return 0;
  }
  
  static void nft_hash_destroy(const struct nft_set *set)
  {
  	struct nft_hash *priv = nft_set_priv(set);
  	struct nft_hash_elem *he;
  	struct hlist_node *next;
  	int i;
  
  	for (i = 0; i < priv->buckets; i++) {
  		hlist_for_each_entry_safe(he, next, &priv->table[i], node) {
  			hlist_del_rcu(&he->node);
  			nft_set_elem_destroy(set, he, true);
  		}
  	}
  }

  static bool nft_hash_estimate(const struct nft_set_desc *desc, u32 features,
  			      struct nft_set_estimate *est)
  {
  	est->size   = sizeof(struct nft_hash) +
  		      nft_hash_buckets(desc->size) * sizeof(struct hlist_head) +
  		      desc->size * sizeof(struct nft_hash_elem);

  	est->lookup = NFT_SET_CLASS_O_1;

  	est->space  = NFT_SET_CLASS_O_N;

  
  	return true;
  }

  static struct nft_set_type nft_hash_type;

  static struct nft_set_ops nft_rhash_ops __read_mostly = {

  	.type		= &nft_hash_type,

  	.privsize       = nft_rhash_privsize,
  	.elemsize	= offsetof(struct nft_rhash_elem, ext),
  	.estimate	= nft_rhash_estimate,
  	.init		= nft_rhash_init,
  	.destroy	= nft_rhash_destroy,
  	.insert		= nft_rhash_insert,
  	.activate	= nft_rhash_activate,
  	.deactivate	= nft_rhash_deactivate,
  	.flush		= nft_rhash_flush,
  	.remove		= nft_rhash_remove,
  	.lookup		= nft_rhash_lookup,
  	.update		= nft_rhash_update,
  	.walk		= nft_rhash_walk,

  	.features	= NFT_SET_MAP | NFT_SET_OBJECT | NFT_SET_TIMEOUT,

  };

  static struct nft_set_ops nft_hash_ops __read_mostly = {
  	.type		= &nft_hash_type,
  	.privsize       = nft_hash_privsize,
  	.elemsize	= offsetof(struct nft_hash_elem, ext),
  	.estimate	= nft_hash_estimate,
  	.init		= nft_hash_init,
  	.destroy	= nft_hash_destroy,
  	.insert		= nft_hash_insert,
  	.activate	= nft_hash_activate,
  	.deactivate	= nft_hash_deactivate,
  	.flush		= nft_hash_flush,
  	.remove		= nft_hash_remove,
  	.lookup		= nft_hash_lookup,
  	.walk		= nft_hash_walk,
  	.features	= NFT_SET_MAP | NFT_SET_OBJECT,
  };

  static struct nft_set_ops nft_hash_fast_ops __read_mostly = {
  	.type		= &nft_hash_type,
  	.privsize       = nft_hash_privsize,
  	.elemsize	= offsetof(struct nft_hash_elem, ext),
  	.estimate	= nft_hash_estimate,
  	.init		= nft_hash_init,
  	.destroy	= nft_hash_destroy,
  	.insert		= nft_hash_insert,
  	.activate	= nft_hash_activate,
  	.deactivate	= nft_hash_deactivate,
  	.flush		= nft_hash_flush,
  	.remove		= nft_hash_remove,
  	.lookup		= nft_hash_lookup_fast,
  	.walk		= nft_hash_walk,
  	.features	= NFT_SET_MAP | NFT_SET_OBJECT,
  };

  static const struct nft_set_ops *
  nft_hash_select_ops(const struct nft_ctx *ctx, const struct nft_set_desc *desc,
  		    u32 flags)
  {

  	if (desc->size) {
  		switch (desc->klen) {

  		case 4:
  			return &nft_hash_fast_ops;
  		default:
  			return &nft_hash_ops;
  		}
  	}

  
  	return &nft_rhash_ops;
  }

  static struct nft_set_type nft_hash_type __read_mostly = {

  	.select_ops	= nft_hash_select_ops,

  	.owner		= THIS_MODULE,

  };
  
  static int __init nft_hash_module_init(void)
  {

  	return nft_register_set(&nft_hash_type);

  }
  
  static void __exit nft_hash_module_exit(void)
  {

  	nft_unregister_set(&nft_hash_type);

  }
  
  module_init(nft_hash_module_init);
  module_exit(nft_hash_module_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");

  MODULE_ALIAS_NFT_SET();