// SPDX-License-Identifier: GPL-2.0-only

  /*

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

   *

   * 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_core.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(&priv->ht, &arg, nft_rhash_params);

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

  	return !!he;

  }

  static void *nft_rhash_get(const struct net *net, const struct nft_set *set,
  			   const struct nft_set_elem *elem, unsigned int flags)
  {
  	struct nft_rhash *priv = nft_set_priv(set);
  	struct nft_rhash_elem *he;
  	struct nft_rhash_cmp_arg arg = {
  		.genmask = nft_genmask_cur(net),
  		.set	 = set,
  		.key	 = elem->key.val.data,
  	};

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

  	if (he != NULL)
  		return he;
  
  	return ERR_PTR(-ENOENT);
  }

  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(&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(&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 bool nft_rhash_delete(const struct nft_set *set,
  			     const u32 *key)
  {
  	struct nft_rhash *priv = nft_set_priv(set);
  	struct nft_rhash_cmp_arg arg = {
  		.genmask = NFT_GENMASK_ANY,
  		.set = set,
  		.key = key,
  	};
  	struct nft_rhash_elem *he;
  
  	he = rhashtable_lookup(&priv->ht, &arg, nft_rhash_params);
  	if (he == NULL)
  		return false;
  
  	return rhashtable_remove_fast(&priv->ht, &he->node, nft_rhash_params) == 0;
  }

  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;

  	rhashtable_walk_enter(&priv->ht, &hti);

  	rhashtable_walk_start(&hti);

  
  	while ((he = rhashtable_walk_next(&hti))) {
  		if (IS_ERR(he)) {

  			if (PTR_ERR(he) != -EAGAIN) {
  				iter->err = PTR_ERR(he);
  				break;

  			}

  
  			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)

  			break;

  cont:

  		iter->count++;

  	}

  	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;

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

  	set  = nft_set_container_of(priv);

  	rhashtable_walk_enter(&priv->ht, &hti);

  	rhashtable_walk_start(&hti);

  
  	while ((he = rhashtable_walk_next(&hti))) {
  		if (IS_ERR(he)) {
  			if (PTR_ERR(he) != -EAGAIN)

  				break;

  			continue;
  		}

  		if (nft_set_ext_exists(&he->ext, NFT_SET_EXT_EXPR)) {
  			struct nft_expr *expr = nft_set_ext_expr(&he->ext);
  
  			if (expr->ops->gc &&
  			    expr->ops->gc(read_pnet(&set->net), expr))
  				goto gc;
  		}

  		if (!nft_set_elem_expired(&he->ext))
  			continue;

  gc:

  		if (nft_set_elem_mark_busy(&he->ext))
  			continue;
  
  		gcb = nft_set_gc_batch_check(set, gcb, GFP_ATOMIC);
  		if (gcb == NULL)

  			break;

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

  		atomic_dec(&set->nelems);

  		nft_set_gc_batch_add(gcb, he);
  	}

  	rhashtable_walk_stop(&hti);
  	rhashtable_walk_exit(&hti);
  
  	nft_set_gc_batch_complete(gcb);

  	queue_delayed_work(system_power_efficient_wq, &priv->gc_work,
  			   nft_set_gc_interval(set));
  }

  static u64 nft_rhash_privsize(const struct nlattr * const nla[],
  			      const struct nft_set_desc *desc)

  {

  	return sizeof(struct nft_rhash);

  }

  static void nft_rhash_gc_init(const struct nft_set *set)
  {
  	struct nft_rhash *priv = nft_set_priv(set);
  
  	queue_delayed_work(system_power_efficient_wq, &priv->gc_work,
  			   nft_set_gc_interval(set));
  }

  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)

  		nft_rhash_gc_init(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;
  }

  static void *nft_hash_get(const struct net *net, const struct nft_set *set,
  			  const struct nft_set_elem *elem, unsigned int flags)
  {
  	struct nft_hash *priv = nft_set_priv(set);
  	u8 genmask = nft_genmask_cur(net);
  	struct nft_hash_elem *he;
  	u32 hash;
  
  	hash = jhash(elem->key.val.data, 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), elem->key.val.data, set->klen) &&
  		    nft_set_elem_active(&he->ext, genmask))
  			return he;
  	}
  	return ERR_PTR(-ENOENT);
  }

  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 = *key;

  	hash = jhash_1word(k1, priv->seed);
  	hash = reciprocal_scale(hash, priv->buckets);
  	hlist_for_each_entry_rcu(he, &priv->table[hash], node) {

  		k2 = *(u32 *)nft_set_ext_key(&he->ext)->data;

  		if (k1 == k2 &&
  		    nft_set_elem_active(&he->ext, genmask)) {
  			*ext = &he->ext;
  			return true;
  		}
  	}
  	return false;
  }

  static u32 nft_jhash(const struct nft_set *set, const struct nft_hash *priv,
  		     const struct nft_set_ext *ext)
  {
  	const struct nft_data *key = nft_set_ext_key(ext);
  	u32 hash, k1;
  
  	if (set->klen == 4) {
  		k1 = *(u32 *)key;
  		hash = jhash_1word(k1, priv->seed);
  	} else {
  		hash = jhash(key, set->klen, priv->seed);
  	}
  	hash = reciprocal_scale(hash, priv->buckets);
  
  	return hash;
  }

  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 = nft_jhash(set, priv, &this->ext);

  	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 = nft_jhash(set, priv, &this->ext);

  	hlist_for_each_entry(he, &priv->table[hash], node) {

  		if (!memcmp(nft_set_ext_key(&he->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 u64 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)
  {

  	if (!desc->size)
  		return false;
  
  	if (desc->klen == 4)
  		return false;

  	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 bool nft_hash_fast_estimate(const struct nft_set_desc *desc, u32 features,
  			      struct nft_set_estimate *est)
  {
  	if (!desc->size)
  		return false;

  	if (desc->klen != 4)
  		return false;

  	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;

  }

  struct nft_set_type nft_set_rhash_type __read_mostly = {

  	.owner		= THIS_MODULE,
  	.features	= NFT_SET_MAP | NFT_SET_OBJECT |
  			  NFT_SET_TIMEOUT | NFT_SET_EVAL,
  	.ops		= {
  		.privsize       = nft_rhash_privsize,
  		.elemsize	= offsetof(struct nft_rhash_elem, ext),
  		.estimate	= nft_rhash_estimate,
  		.init		= nft_rhash_init,

  		.gc_init	= nft_rhash_gc_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,

  		.delete		= nft_rhash_delete,

  		.walk		= nft_rhash_walk,
  		.get		= nft_rhash_get,
  	},
  };

  struct nft_set_type nft_set_hash_type __read_mostly = {

  	.owner		= THIS_MODULE,

  	.features	= NFT_SET_MAP | NFT_SET_OBJECT,
  	.ops		= {
  		.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,
  		.get		= nft_hash_get,
  	},
  };

  struct nft_set_type nft_set_hash_fast_type __read_mostly = {

  	.owner		= THIS_MODULE,
  	.features	= NFT_SET_MAP | NFT_SET_OBJECT,
  	.ops		= {
  		.privsize       = nft_hash_privsize,
  		.elemsize	= offsetof(struct nft_hash_elem, ext),
  		.estimate	= nft_hash_fast_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,
  		.get		= nft_hash_get,
  	},

  };