text: /* Connection state tracking for netfilter.  This is separated from,
     but required by, the NAT layer; it can also be used by an iptables
     extension. */
  
  /* (C) 1999-2001 Paul `Rusty' Russell
   * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
   * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
   * (C) 2005-2012 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.
   */
  
  #include <linux/types.h>
  #include <linux/netfilter.h>
  #include <linux/module.h>
  #include <linux/sched.h>
  #include <linux/skbuff.h>
  #include <linux/proc_fs.h>
  #include <linux/vmalloc.h>
  #include <linux/stddef.h>
  #include <linux/slab.h>
  #include <linux/random.h>
  #include <linux/jhash.h>
  #include <linux/err.h>
  #include <linux/percpu.h>
  #include <linux/moduleparam.h>
  #include <linux/notifier.h>
  #include <linux/kernel.h>
  #include <linux/netdevice.h>
  #include <linux/socket.h>
  #include <linux/mm.h>
  #include <linux/nsproxy.h>
  #include <linux/rculist_nulls.h>
  
  #include <net/netfilter/nf_conntrack.h>
  #include <net/netfilter/nf_conntrack_l3proto.h>
  #include <net/netfilter/nf_conntrack_l4proto.h>
  #include <net/netfilter/nf_conntrack_expect.h>
  #include <net/netfilter/nf_conntrack_helper.h>
  #include <net/netfilter/nf_conntrack_seqadj.h>
  #include <net/netfilter/nf_conntrack_core.h>
  #include <net/netfilter/nf_conntrack_extend.h>
  #include <net/netfilter/nf_conntrack_acct.h>
  #include <net/netfilter/nf_conntrack_ecache.h>
  #include <net/netfilter/nf_conntrack_zones.h>
  #include <net/netfilter/nf_conntrack_timestamp.h>
  #include <net/netfilter/nf_conntrack_timeout.h>
  #include <net/netfilter/nf_conntrack_labels.h>
  #include <net/netfilter/nf_conntrack_synproxy.h>
  #include <net/netfilter/nf_nat.h>
  #include <net/netfilter/nf_nat_core.h>
  #include <net/netfilter/nf_nat_helper.h>
  
  #define NF_CONNTRACK_VERSION	"0.5.0"
  
  int (*nfnetlink_parse_nat_setup_hook)(struct nf_conn *ct,
  				      enum nf_nat_manip_type manip,
  				      const struct nlattr *attr) __read_mostly;
  EXPORT_SYMBOL_GPL(nfnetlink_parse_nat_setup_hook);
  
  __cacheline_aligned_in_smp spinlock_t nf_conntrack_locks[CONNTRACK_LOCKS];
  EXPORT_SYMBOL_GPL(nf_conntrack_locks);
  
  __cacheline_aligned_in_smp DEFINE_SPINLOCK(nf_conntrack_expect_lock);
  EXPORT_SYMBOL_GPL(nf_conntrack_expect_lock);
  
  static void nf_conntrack_double_unlock(unsigned int h1, unsigned int h2)
  {
  	h1 %= CONNTRACK_LOCKS;
  	h2 %= CONNTRACK_LOCKS;
  	spin_unlock(&nf_conntrack_locks[h1]);
  	if (h1 != h2)
  		spin_unlock(&nf_conntrack_locks[h2]);
  }
  
  /* return true if we need to recompute hashes (in case hash table was resized) */
  static bool nf_conntrack_double_lock(struct net *net, unsigned int h1,
  				     unsigned int h2, unsigned int sequence)
  {
  	h1 %= CONNTRACK_LOCKS;
  	h2 %= CONNTRACK_LOCKS;
  	if (h1 <= h2) {
  		spin_lock(&nf_conntrack_locks[h1]);
  		if (h1 != h2)
  			spin_lock_nested(&nf_conntrack_locks[h2],
  					 SINGLE_DEPTH_NESTING);
  	} else {
  		spin_lock(&nf_conntrack_locks[h2]);
  		spin_lock_nested(&nf_conntrack_locks[h1],
  				 SINGLE_DEPTH_NESTING);
  	}
  	if (read_seqcount_retry(&net->ct.generation, sequence)) {
  		nf_conntrack_double_unlock(h1, h2);
  		return true;
  	}
  	return false;
  }
  
  static void nf_conntrack_all_lock(void)
  {
  	int i;
  
  	for (i = 0; i < CONNTRACK_LOCKS; i++)
  		spin_lock_nested(&nf_conntrack_locks[i], i);
  }
  
  static void nf_conntrack_all_unlock(void)
  {
  	int i;
  
  	for (i = 0; i < CONNTRACK_LOCKS; i++)
  		spin_unlock(&nf_conntrack_locks[i]);
  }
  
  unsigned int nf_conntrack_htable_size __read_mostly;
  EXPORT_SYMBOL_GPL(nf_conntrack_htable_size);
  
  unsigned int nf_conntrack_max __read_mostly;
  EXPORT_SYMBOL_GPL(nf_conntrack_max);
  
  DEFINE_PER_CPU(struct nf_conn, nf_conntrack_untracked);
  EXPORT_PER_CPU_SYMBOL(nf_conntrack_untracked);
  
  unsigned int nf_conntrack_hash_rnd __read_mostly;
  EXPORT_SYMBOL_GPL(nf_conntrack_hash_rnd);
  
  static u32 hash_conntrack_raw(const struct nf_conntrack_tuple *tuple, u16 zone)
  {
  	unsigned int n;
  
  	/* The direction must be ignored, so we hash everything up to the
  	 * destination ports (which is a multiple of 4) and treat the last
  	 * three bytes manually.
  	 */
  	n = (sizeof(tuple->src) + sizeof(tuple->dst.u3)) / sizeof(u32);
  	return jhash2((u32 *)tuple, n, zone ^ nf_conntrack_hash_rnd ^
  		      (((__force __u16)tuple->dst.u.all << 16) |
  		      tuple->dst.protonum));
  }
  
  static u32 __hash_bucket(u32 hash, unsigned int size)
  {
  	return reciprocal_scale(hash, size);
  }
  
  static u32 hash_bucket(u32 hash, const struct net *net)
  {
  	return __hash_bucket(hash, net->ct.htable_size);
  }
  
  static u_int32_t __hash_conntrack(const struct nf_conntrack_tuple *tuple,
  				  u16 zone, unsigned int size)
  {
  	return __hash_bucket(hash_conntrack_raw(tuple, zone), size);
  }
  
  static inline u_int32_t hash_conntrack(const struct net *net, u16 zone,
  				       const struct nf_conntrack_tuple *tuple)
  {
  	return __hash_conntrack(tuple, zone, net->ct.htable_size);
  }
  
  bool
  nf_ct_get_tuple(const struct sk_buff *skb,
  		unsigned int nhoff,
  		unsigned int dataoff,
  		u_int16_t l3num,
  		u_int8_t protonum,
  		struct nf_conntrack_tuple *tuple,
  		const struct nf_conntrack_l3proto *l3proto,
  		const struct nf_conntrack_l4proto *l4proto)
  {
  	memset(tuple, 0, sizeof(*tuple));
  
  	tuple->src.l3num = l3num;
  	if (l3proto->pkt_to_tuple(skb, nhoff, tuple) == 0)
  		return false;
  
  	tuple->dst.protonum = protonum;
  	tuple->dst.dir = IP_CT_DIR_ORIGINAL;
  
  	return l4proto->pkt_to_tuple(skb, dataoff, tuple);
  }
  EXPORT_SYMBOL_GPL(nf_ct_get_tuple);
  
  bool nf_ct_get_tuplepr(const struct sk_buff *skb, unsigned int nhoff,
  		       u_int16_t l3num, struct nf_conntrack_tuple *tuple)
  {
  	struct nf_conntrack_l3proto *l3proto;
  	struct nf_conntrack_l4proto *l4proto;
  	unsigned int protoff;
  	u_int8_t protonum;
  	int ret;
  
  	rcu_read_lock();
  
  	l3proto = __nf_ct_l3proto_find(l3num);
  	ret = l3proto->get_l4proto(skb, nhoff, &protoff, &protonum);
  	if (ret != NF_ACCEPT) {
  		rcu_read_unlock();
  		return false;
  	}
  
  	l4proto = __nf_ct_l4proto_find(l3num, protonum);
  
  	ret = nf_ct_get_tuple(skb, nhoff, protoff, l3num, protonum, tuple,
  			      l3proto, l4proto);
  
  	rcu_read_unlock();
  	return ret;
  }
  EXPORT_SYMBOL_GPL(nf_ct_get_tuplepr);
  
  bool
  nf_ct_invert_tuple(struct nf_conntrack_tuple *inverse,
  		   const struct nf_conntrack_tuple *orig,
  		   const struct nf_conntrack_l3proto *l3proto,
  		   const struct nf_conntrack_l4proto *l4proto)
  {
  	memset(inverse, 0, sizeof(*inverse));
  
  	inverse->src.l3num = orig->src.l3num;
  	if (l3proto->invert_tuple(inverse, orig) == 0)
  		return false;
  
  	inverse->dst.dir = !orig->dst.dir;
  
  	inverse->dst.protonum = orig->dst.protonum;
  	return l4proto->invert_tuple(inverse, orig);
  }
  EXPORT_SYMBOL_GPL(nf_ct_invert_tuple);
  
  static void
  clean_from_lists(struct nf_conn *ct)
  {
  	pr_debug("clean_from_lists(%p)\n", ct);
  	hlist_nulls_del_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode);
  	hlist_nulls_del_rcu(&ct->tuplehash[IP_CT_DIR_REPLY].hnnode);
  
  	/* Destroy all pending expectations */
  	nf_ct_remove_expectations(ct);
  }
  
  /* must be called with local_bh_disable */
  static void nf_ct_add_to_dying_list(struct nf_conn *ct)
  {
  	struct ct_pcpu *pcpu;
  
  	/* add this conntrack to the (per cpu) dying list */
  	ct->cpu = smp_processor_id();
  	pcpu = per_cpu_ptr(nf_ct_net(ct)->ct.pcpu_lists, ct->cpu);
  
  	spin_lock(&pcpu->lock);
  	hlist_nulls_add_head(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode,
  			     &pcpu->dying);
  	spin_unlock(&pcpu->lock);
  }
  
  /* must be called with local_bh_disable */
  static void nf_ct_add_to_unconfirmed_list(struct nf_conn *ct)
  {
  	struct ct_pcpu *pcpu;
  
  	/* add this conntrack to the (per cpu) unconfirmed list */
  	ct->cpu = smp_processor_id();
  	pcpu = per_cpu_ptr(nf_ct_net(ct)->ct.pcpu_lists, ct->cpu);
  
  	spin_lock(&pcpu->lock);
  	hlist_nulls_add_head(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode,
  			     &pcpu->unconfirmed);
  	spin_unlock(&pcpu->lock);
  }
  
  /* must be called with local_bh_disable */
  static void nf_ct_del_from_dying_or_unconfirmed_list(struct nf_conn *ct)
  {
  	struct ct_pcpu *pcpu;
  
  	/* We overload first tuple to link into unconfirmed or dying list.*/
  	pcpu = per_cpu_ptr(nf_ct_net(ct)->ct.pcpu_lists, ct->cpu);
  
  	spin_lock(&pcpu->lock);
  	BUG_ON(hlist_nulls_unhashed(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode));
  	hlist_nulls_del_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode);
  	spin_unlock(&pcpu->lock);
  }
  
  /* Released via destroy_conntrack() */
  struct nf_conn *nf_ct_tmpl_alloc(struct net *net, u16 zone, gfp_t flags)
  {
  	struct nf_conn *tmpl;
  
  	tmpl = kzalloc(sizeof(*tmpl), flags);
  	if (tmpl == NULL)
  		return NULL;
  
  	tmpl->status = IPS_TEMPLATE;
  	write_pnet(&tmpl->ct_net, net);
  
  #ifdef CONFIG_NF_CONNTRACK_ZONES
  	if (zone) {
  		struct nf_conntrack_zone *nf_ct_zone;
  
  		nf_ct_zone = nf_ct_ext_add(tmpl, NF_CT_EXT_ZONE, flags);
  		if (!nf_ct_zone)
  			goto out_free;
  		nf_ct_zone->id = zone;
  	}
  #endif
  	atomic_set(&tmpl->ct_general.use, 0);
  
  	return tmpl;
  #ifdef CONFIG_NF_CONNTRACK_ZONES
  out_free:
  	kfree(tmpl);
  	return NULL;
  #endif
  }
  EXPORT_SYMBOL_GPL(nf_ct_tmpl_alloc);
  
  void nf_ct_tmpl_free(struct nf_conn *tmpl)
  {
  	nf_ct_ext_destroy(tmpl);
  	nf_ct_ext_free(tmpl);
  	kfree(tmpl);
  }
  EXPORT_SYMBOL_GPL(nf_ct_tmpl_free);
  
  static void
  destroy_conntrack(struct nf_conntrack *nfct)
  {
  	struct nf_conn *ct = (struct nf_conn *)nfct;
  	struct net *net = nf_ct_net(ct);
  	struct nf_conntrack_l4proto *l4proto;
  
  	pr_debug("destroy_conntrack(%p)\n", ct);
  	NF_CT_ASSERT(atomic_read(&nfct->use) == 0);
  	NF_CT_ASSERT(!timer_pending(&ct->timeout));
  
  	if (unlikely(nf_ct_is_template(ct))) {
  		nf_ct_tmpl_free(ct);
  		return;
  	}
  	rcu_read_lock();
  	l4proto = __nf_ct_l4proto_find(nf_ct_l3num(ct), nf_ct_protonum(ct));
  	if (l4proto && l4proto->destroy)
  		l4proto->destroy(ct);
  
  	rcu_read_unlock();
  
  	local_bh_disable();
  	/* Expectations will have been removed in clean_from_lists,
  	 * except TFTP can create an expectation on the first packet,
  	 * before connection is in the list, so we need to clean here,
  	 * too.
  	 */
  	nf_ct_remove_expectations(ct);
  
  	nf_ct_del_from_dying_or_unconfirmed_list(ct);
  
  	NF_CT_STAT_INC(net, delete);
  	local_bh_enable();
  
  	if (ct->master)
  		nf_ct_put(ct->master);
  
  	pr_debug("destroy_conntrack: returning ct=%p to slab\n", ct);
  	nf_conntrack_free(ct);
  }
  
  static void nf_ct_delete_from_lists(struct nf_conn *ct)
  {
  	struct net *net = nf_ct_net(ct);
  	unsigned int hash, reply_hash;
  	u16 zone = nf_ct_zone(ct);
  	unsigned int sequence;
  
  	nf_ct_helper_destroy(ct);
  
  	local_bh_disable();
  	do {
  		sequence = read_seqcount_begin(&net->ct.generation);
  		hash = hash_conntrack(net, zone,
  				      &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
  		reply_hash = hash_conntrack(net, zone,
  					   &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
  	} while (nf_conntrack_double_lock(net, hash, reply_hash, sequence));
  
  	clean_from_lists(ct);
  	nf_conntrack_double_unlock(hash, reply_hash);
  
  	nf_ct_add_to_dying_list(ct);
  
  	NF_CT_STAT_INC(net, delete_list);
  	local_bh_enable();
  }
  
  bool nf_ct_delete(struct nf_conn *ct, u32 portid, int report)
  {
  	struct nf_conn_tstamp *tstamp;
  
  	tstamp = nf_conn_tstamp_find(ct);
  	if (tstamp && tstamp->stop == 0)
  		tstamp->stop = ktime_get_real_ns();
  
  	if (nf_ct_is_dying(ct))
  		goto delete;
  
  	if (nf_conntrack_event_report(IPCT_DESTROY, ct,
  				    portid, report) < 0) {
  		/* destroy event was not delivered */
  		nf_ct_delete_from_lists(ct);
  		nf_conntrack_ecache_delayed_work(nf_ct_net(ct));
  		return false;
  	}
  
  	nf_conntrack_ecache_work(nf_ct_net(ct));
  	set_bit(IPS_DYING_BIT, &ct->status);
   delete:
  	nf_ct_delete_from_lists(ct);
  	nf_ct_put(ct);
  	return true;
  }
  EXPORT_SYMBOL_GPL(nf_ct_delete);
  
  static void death_by_timeout(unsigned long ul_conntrack)
  {
  	nf_ct_delete((struct nf_conn *)ul_conntrack, 0, 0);
  }
  
  static inline bool
  nf_ct_key_equal(struct nf_conntrack_tuple_hash *h,
  			const struct nf_conntrack_tuple *tuple,
  			u16 zone)
  {
  	struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
  
  	/* A conntrack can be recreated with the equal tuple,
  	 * so we need to check that the conntrack is confirmed
  	 */
  	return nf_ct_tuple_equal(tuple, &h->tuple) &&
  		nf_ct_zone(ct) == zone &&
  		nf_ct_is_confirmed(ct);
  }
  
  /*
   * Warning :
   * - Caller must take a reference on returned object
   *   and recheck nf_ct_tuple_equal(tuple, &h->tuple)
   */
  static struct nf_conntrack_tuple_hash *
  ____nf_conntrack_find(struct net *net, u16 zone,
  		      const struct nf_conntrack_tuple *tuple, u32 hash)
  {
  	struct nf_conntrack_tuple_hash *h;
  	struct hlist_nulls_node *n;
  	unsigned int bucket = hash_bucket(hash, net);
  
  	/* Disable BHs the entire time since we normally need to disable them
  	 * at least once for the stats anyway.
  	 */
  	local_bh_disable();
  begin:
  	hlist_nulls_for_each_entry_rcu(h, n, &net->ct.hash[bucket], hnnode) {
  		if (nf_ct_key_equal(h, tuple, zone)) {
  			NF_CT_STAT_INC(net, found);
  			local_bh_enable();
  			return h;
  		}
  		NF_CT_STAT_INC(net, searched);
  	}
  	/*
  	 * if the nulls value we got at the end of this lookup is
  	 * not the expected one, we must restart lookup.
  	 * We probably met an item that was moved to another chain.
  	 */
  	if (get_nulls_value(n) != bucket) {
  		NF_CT_STAT_INC(net, search_restart);
  		goto begin;
  	}
  	local_bh_enable();
  
  	return NULL;
  }
  
  /* Find a connection corresponding to a tuple. */
  static struct nf_conntrack_tuple_hash *
  __nf_conntrack_find_get(struct net *net, u16 zone,
  			const struct nf_conntrack_tuple *tuple, u32 hash)
  {
  	struct nf_conntrack_tuple_hash *h;
  	struct nf_conn *ct;
  
  	rcu_read_lock();
  begin:
  	h = ____nf_conntrack_find(net, zone, tuple, hash);
  	if (h) {
  		ct = nf_ct_tuplehash_to_ctrack(h);
  		if (unlikely(nf_ct_is_dying(ct) ||
  			     !atomic_inc_not_zero(&ct->ct_general.use)))
  			h = NULL;
  		else {
  			if (unlikely(!nf_ct_key_equal(h, tuple, zone))) {
  				nf_ct_put(ct);
  				goto begin;
  			}
  		}
  	}
  	rcu_read_unlock();
  
  	return h;
  }
  
  struct nf_conntrack_tuple_hash *
  nf_conntrack_find_get(struct net *net, u16 zone,
  		      const struct nf_conntrack_tuple *tuple)
  {
  	return __nf_conntrack_find_get(net, zone, tuple,
  				       hash_conntrack_raw(tuple, zone));
  }
  EXPORT_SYMBOL_GPL(nf_conntrack_find_get);
  
  static void __nf_conntrack_hash_insert(struct nf_conn *ct,
  				       unsigned int hash,
  				       unsigned int reply_hash)
  {
  	struct net *net = nf_ct_net(ct);
  
  	hlist_nulls_add_head_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode,
  			   &net->ct.hash[hash]);
  	hlist_nulls_add_head_rcu(&ct->tuplehash[IP_CT_DIR_REPLY].hnnode,
  			   &net->ct.hash[reply_hash]);
  }
  
  int
  nf_conntrack_hash_check_insert(struct nf_conn *ct)
  {
  	struct net *net = nf_ct_net(ct);
  	unsigned int hash, reply_hash;
  	struct nf_conntrack_tuple_hash *h;
  	struct hlist_nulls_node *n;
  	u16 zone;
  	unsigned int sequence;
  
  	zone = nf_ct_zone(ct);
  
  	local_bh_disable();
  	do {
  		sequence = read_seqcount_begin(&net->ct.generation);
  		hash = hash_conntrack(net, zone,
  				      &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
  		reply_hash = hash_conntrack(net, zone,
  					   &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
  	} while (nf_conntrack_double_lock(net, hash, reply_hash, sequence));
  
  	/* See if there's one in the list already, including reverse */
  	hlist_nulls_for_each_entry(h, n, &net->ct.hash[hash], hnnode)
  		if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
  				      &h->tuple) &&
  		    zone == nf_ct_zone(nf_ct_tuplehash_to_ctrack(h)))
  			goto out;
  	hlist_nulls_for_each_entry(h, n, &net->ct.hash[reply_hash], hnnode)
  		if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_REPLY].tuple,
  				      &h->tuple) &&
  		    zone == nf_ct_zone(nf_ct_tuplehash_to_ctrack(h)))
  			goto out;
  
  	add_timer(&ct->timeout);
  	smp_wmb();
  	/* The caller holds a reference to this object */
  	atomic_set(&ct->ct_general.use, 2);
  	__nf_conntrack_hash_insert(ct, hash, reply_hash);
  	nf_conntrack_double_unlock(hash, reply_hash);
  	NF_CT_STAT_INC(net, insert);
  	local_bh_enable();
  	return 0;
  
  out:
  	nf_conntrack_double_unlock(hash, reply_hash);
  	NF_CT_STAT_INC(net, insert_failed);
  	local_bh_enable();
  	return -EEXIST;
  }
  EXPORT_SYMBOL_GPL(nf_conntrack_hash_check_insert);
  
  /* Confirm a connection given skb; places it in hash table */
  int
  __nf_conntrack_confirm(struct sk_buff *skb)
  {
  	unsigned int hash, reply_hash;
  	struct nf_conntrack_tuple_hash *h;
  	struct nf_conn *ct;
  	struct nf_conn_help *help;
  	struct nf_conn_tstamp *tstamp;
  	struct hlist_nulls_node *n;
  	enum ip_conntrack_info ctinfo;
  	struct net *net;
  	u16 zone;
  	unsigned int sequence;
  
  	ct = nf_ct_get(skb, &ctinfo);
  	net = nf_ct_net(ct);
  
  	/* ipt_REJECT uses nf_conntrack_attach to attach related
  	   ICMP/TCP RST packets in other direction.  Actual packet
  	   which created connection will be IP_CT_NEW or for an
  	   expected connection, IP_CT_RELATED. */
  	if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
  		return NF_ACCEPT;
  
  	zone = nf_ct_zone(ct);
  	local_bh_disable();
  
  	do {
  		sequence = read_seqcount_begin(&net->ct.generation);
  		/* reuse the hash saved before */
  		hash = *(unsigned long *)&ct->tuplehash[IP_CT_DIR_REPLY].hnnode.pprev;
  		hash = hash_bucket(hash, net);
  		reply_hash = hash_conntrack(net, zone,
  					   &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
  
  	} while (nf_conntrack_double_lock(net, hash, reply_hash, sequence));
  
  	/* We're not in hash table, and we refuse to set up related
  	 * connections for unconfirmed conns.  But packet copies and
  	 * REJECT will give spurious warnings here.
  	 */
  	/* NF_CT_ASSERT(atomic_read(&ct->ct_general.use) == 1); */
  
  	/* No external references means no one else could have
  	 * confirmed us.
  	 */
  	NF_CT_ASSERT(!nf_ct_is_confirmed(ct));
  	pr_debug("Confirming conntrack %p\n", ct);
  	/* We have to check the DYING flag after unlink to prevent
  	 * a race against nf_ct_get_next_corpse() possibly called from
  	 * user context, else we insert an already 'dead' hash, blocking
  	 * further use of that particular connection -JM.
  	 */
  	nf_ct_del_from_dying_or_unconfirmed_list(ct);
  
  	if (unlikely(nf_ct_is_dying(ct)))
  		goto out;
  
  	/* See if there's one in the list already, including reverse:
  	   NAT could have grabbed it without realizing, since we're
  	   not in the hash.  If there is, we lost race. */
  	hlist_nulls_for_each_entry(h, n, &net->ct.hash[hash], hnnode)
  		if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
  				      &h->tuple) &&
  		    zone == nf_ct_zone(nf_ct_tuplehash_to_ctrack(h)))
  			goto out;
  	hlist_nulls_for_each_entry(h, n, &net->ct.hash[reply_hash], hnnode)
  		if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_REPLY].tuple,
  				      &h->tuple) &&
  		    zone == nf_ct_zone(nf_ct_tuplehash_to_ctrack(h)))
  			goto out;
  
  	/* Timer relative to confirmation time, not original
  	   setting time, otherwise we'd get timer wrap in
  	   weird delay cases. */
  	ct->timeout.expires += jiffies;
  	add_timer(&ct->timeout);
  	atomic_inc(&ct->ct_general.use);
  	ct->status |= IPS_CONFIRMED;
  
  	/* set conntrack timestamp, if enabled. */
  	tstamp = nf_conn_tstamp_find(ct);
  	if (tstamp) {
  		if (skb->tstamp.tv64 == 0)
  			__net_timestamp(skb);
  
  		tstamp->start = ktime_to_ns(skb->tstamp);
  	}
  	/* Since the lookup is lockless, hash insertion must be done after
  	 * starting the timer and setting the CONFIRMED bit. The RCU barriers
  	 * guarantee that no other CPU can find the conntrack before the above
  	 * stores are visible.
  	 */
  	__nf_conntrack_hash_insert(ct, hash, reply_hash);
  	nf_conntrack_double_unlock(hash, reply_hash);
  	NF_CT_STAT_INC(net, insert);
  	local_bh_enable();
  
  	help = nfct_help(ct);
  	if (help && help->helper)
  		nf_conntrack_event_cache(IPCT_HELPER, ct);
  
  	nf_conntrack_event_cache(master_ct(ct) ?
  				 IPCT_RELATED : IPCT_NEW, ct);
  	return NF_ACCEPT;
  
  out:
  	nf_ct_add_to_dying_list(ct);
  	nf_conntrack_double_unlock(hash, reply_hash);
  	NF_CT_STAT_INC(net, insert_failed);
  	local_bh_enable();
  	return NF_DROP;
  }
  EXPORT_SYMBOL_GPL(__nf_conntrack_confirm);
  
  /* Returns true if a connection correspondings to the tuple (required
     for NAT). */
  int
  nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple,
  			 const struct nf_conn *ignored_conntrack)
  {
  	struct net *net = nf_ct_net(ignored_conntrack);
  	struct nf_conntrack_tuple_hash *h;
  	struct hlist_nulls_node *n;
  	struct nf_conn *ct;
  	u16 zone = nf_ct_zone(ignored_conntrack);
  	unsigned int hash = hash_conntrack(net, zone, tuple);
  
  	/* Disable BHs the entire time since we need to disable them at
  	 * least once for the stats anyway.
  	 */
  	rcu_read_lock_bh();
  	hlist_nulls_for_each_entry_rcu(h, n, &net->ct.hash[hash], hnnode) {
  		ct = nf_ct_tuplehash_to_ctrack(h);
  		if (ct != ignored_conntrack &&
  		    nf_ct_tuple_equal(tuple, &h->tuple) &&
  		    nf_ct_zone(ct) == zone) {
  			NF_CT_STAT_INC(net, found);
  			rcu_read_unlock_bh();
  			return 1;
  		}
  		NF_CT_STAT_INC(net, searched);
  	}
  	rcu_read_unlock_bh();
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(nf_conntrack_tuple_taken);
  
  #define NF_CT_EVICTION_RANGE	8
  
  /* There's a small race here where we may free a just-assured
     connection.  Too bad: we're in trouble anyway. */
  static noinline int early_drop(struct net *net, unsigned int _hash)
  {
  	/* Use oldest entry, which is roughly LRU */
  	struct nf_conntrack_tuple_hash *h;
  	struct nf_conn *ct = NULL, *tmp;
  	struct hlist_nulls_node *n;
  	unsigned int i = 0, cnt = 0;
  	int dropped = 0;
  	unsigned int hash, sequence;
  	spinlock_t *lockp;
  
  	local_bh_disable();
  restart:
  	sequence = read_seqcount_begin(&net->ct.generation);
  	hash = hash_bucket(_hash, net);
  	for (; i < net->ct.htable_size; i++) {
  		lockp = &nf_conntrack_locks[hash % CONNTRACK_LOCKS];
  		spin_lock(lockp);
  		if (read_seqcount_retry(&net->ct.generation, sequence)) {
  			spin_unlock(lockp);
  			goto restart;
  		}
  		hlist_nulls_for_each_entry_rcu(h, n, &net->ct.hash[hash],
  					 hnnode) {
  			tmp = nf_ct_tuplehash_to_ctrack(h);
  			if (!test_bit(IPS_ASSURED_BIT, &tmp->status) &&
  			    !nf_ct_is_dying(tmp) &&
  			    atomic_inc_not_zero(&tmp->ct_general.use)) {
  				ct = tmp;
  				break;
  			}
  			cnt++;
  		}
  
  		hash = (hash + 1) % net->ct.htable_size;
  		spin_unlock(lockp);
  
  		if (ct || cnt >= NF_CT_EVICTION_RANGE)
  			break;
  
  	}
  	local_bh_enable();
  
  	if (!ct)
  		return dropped;
  
  	if (del_timer(&ct->timeout)) {
  		if (nf_ct_delete(ct, 0, 0)) {
  			dropped = 1;
  			NF_CT_STAT_INC_ATOMIC(net, early_drop);
  		}
  	}
  	nf_ct_put(ct);
  	return dropped;
  }
  
  void init_nf_conntrack_hash_rnd(void)
  {
  	unsigned int rand;
  
  	/*
  	 * Why not initialize nf_conntrack_rnd in a "init()" function ?
  	 * Because there isn't enough entropy when system initializing,
  	 * and we initialize it as late as possible.
  	 */
  	do {
  		get_random_bytes(&rand, sizeof(rand));
  	} while (!rand);
  	cmpxchg(&nf_conntrack_hash_rnd, 0, rand);
  }
  
  static struct nf_conn *
  __nf_conntrack_alloc(struct net *net, u16 zone,
  		     const struct nf_conntrack_tuple *orig,
  		     const struct nf_conntrack_tuple *repl,
  		     gfp_t gfp, u32 hash)
  {
  	struct nf_conn *ct;
  
  	if (unlikely(!nf_conntrack_hash_rnd)) {
  		init_nf_conntrack_hash_rnd();
  		/* recompute the hash as nf_conntrack_hash_rnd is initialized */
  		hash = hash_conntrack_raw(orig, zone);
  	}
  
  	/* We don't want any race condition at early drop stage */
  	atomic_inc(&net->ct.count);
  
  	if (nf_conntrack_max &&
  	    unlikely(atomic_read(&net->ct.count) > nf_conntrack_max)) {
  		if (!early_drop(net, hash)) {
  			atomic_dec(&net->ct.count);
  			net_warn_ratelimited("nf_conntrack: table full, dropping packet\n");
  			return ERR_PTR(-ENOMEM);
  		}
  	}
  
  	/*
  	 * Do not use kmem_cache_zalloc(), as this cache uses
  	 * SLAB_DESTROY_BY_RCU.
  	 */
  	ct = kmem_cache_alloc(net->ct.nf_conntrack_cachep, gfp);
  	if (ct == NULL) {
  		atomic_dec(&net->ct.count);
  		return ERR_PTR(-ENOMEM);
  	}
  	spin_lock_init(&ct->lock);
  	ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple = *orig;
  	ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode.pprev = NULL;
  	ct->tuplehash[IP_CT_DIR_REPLY].tuple = *repl;
  	/* save hash for reusing when confirming */
  	*(unsigned long *)(&ct->tuplehash[IP_CT_DIR_REPLY].hnnode.pprev) = hash;
  	ct->status = 0;
  	/* Don't set timer yet: wait for confirmation */
  	setup_timer(&ct->timeout, death_by_timeout, (unsigned long)ct);
  	write_pnet(&ct->ct_net, net);
  	memset(&ct->__nfct_init_offset[0], 0,
  	       offsetof(struct nf_conn, proto) -
  	       offsetof(struct nf_conn, __nfct_init_offset[0]));
  #ifdef CONFIG_NF_CONNTRACK_ZONES
  	if (zone) {
  		struct nf_conntrack_zone *nf_ct_zone;
  
  		nf_ct_zone = nf_ct_ext_add(ct, NF_CT_EXT_ZONE, GFP_ATOMIC);
  		if (!nf_ct_zone)
  			goto out_free;
  		nf_ct_zone->id = zone;
  	}
  #endif
  	/* Because we use RCU lookups, we set ct_general.use to zero before
  	 * this is inserted in any list.
  	 */
  	atomic_set(&ct->ct_general.use, 0);
  	return ct;
  
  #ifdef CONFIG_NF_CONNTRACK_ZONES
  out_free:
  	atomic_dec(&net->ct.count);
  	kmem_cache_free(net->ct.nf_conntrack_cachep, ct);
  	return ERR_PTR(-ENOMEM);
  #endif
  }
  
  struct nf_conn *nf_conntrack_alloc(struct net *net, u16 zone,
  				   const struct nf_conntrack_tuple *orig,
  				   const struct nf_conntrack_tuple *repl,
  				   gfp_t gfp)
  {
  	return __nf_conntrack_alloc(net, zone, orig, repl, gfp, 0);
  }
  EXPORT_SYMBOL_GPL(nf_conntrack_alloc);
  
  void nf_conntrack_free(struct nf_conn *ct)
  {
  	struct net *net = nf_ct_net(ct);
  
  	/* A freed object has refcnt == 0, that's
  	 * the golden rule for SLAB_DESTROY_BY_RCU
  	 */
  	NF_CT_ASSERT(atomic_read(&ct->ct_general.use) == 0);
  
  	nf_ct_ext_destroy(ct);
  	nf_ct_ext_free(ct);
  	kmem_cache_free(net->ct.nf_conntrack_cachep, ct);
  	smp_mb__before_atomic();
  	atomic_dec(&net->ct.count);
  }
  EXPORT_SYMBOL_GPL(nf_conntrack_free);
  
  
  /* Allocate a new conntrack: we return -ENOMEM if classification
     failed due to stress.  Otherwise it really is unclassifiable. */
  static struct nf_conntrack_tuple_hash *
  init_conntrack(struct net *net, struct nf_conn *tmpl,
  	       const struct nf_conntrack_tuple *tuple,
  	       struct nf_conntrack_l3proto *l3proto,
  	       struct nf_conntrack_l4proto *l4proto,
  	       struct sk_buff *skb,
  	       unsigned int dataoff, u32 hash)
  {
  	struct nf_conn *ct;
  	struct nf_conn_help *help;
  	struct nf_conntrack_tuple repl_tuple;
  	struct nf_conntrack_ecache *ecache;
  	struct nf_conntrack_expect *exp = NULL;
  	u16 zone = tmpl ? nf_ct_zone(tmpl) : NF_CT_DEFAULT_ZONE;
  	struct nf_conn_timeout *timeout_ext;
  	unsigned int *timeouts;
  
  	if (!nf_ct_invert_tuple(&repl_tuple, tuple, l3proto, l4proto)) {
  		pr_debug("Can't invert tuple.\n");
  		return NULL;
  	}
  
  	ct = __nf_conntrack_alloc(net, zone, tuple, &repl_tuple, GFP_ATOMIC,
  				  hash);
  	if (IS_ERR(ct))
  		return (struct nf_conntrack_tuple_hash *)ct;
  
  	if (tmpl && nfct_synproxy(tmpl)) {
  		nfct_seqadj_ext_add(ct);
  		nfct_synproxy_ext_add(ct);
  	}
  
  	timeout_ext = tmpl ? nf_ct_timeout_find(tmpl) : NULL;
  	if (timeout_ext)
  		timeouts = NF_CT_TIMEOUT_EXT_DATA(timeout_ext);
  	else
  		timeouts = l4proto->get_timeouts(net);
  
  	if (!l4proto->new(ct, skb, dataoff, timeouts)) {
  		nf_conntrack_free(ct);
  		pr_debug("init conntrack: can't track with proto module\n");
  		return NULL;
  	}
  
  	if (timeout_ext)
  		nf_ct_timeout_ext_add(ct, timeout_ext->timeout, GFP_ATOMIC);
  
  	nf_ct_acct_ext_add(ct, GFP_ATOMIC);
  	nf_ct_tstamp_ext_add(ct, GFP_ATOMIC);
  	nf_ct_labels_ext_add(ct);
  
  	ecache = tmpl ? nf_ct_ecache_find(tmpl) : NULL;
  	nf_ct_ecache_ext_add(ct, ecache ? ecache->ctmask : 0,
  				 ecache ? ecache->expmask : 0,
  			     GFP_ATOMIC);
  
  	local_bh_disable();
  	if (net->ct.expect_count) {
  		spin_lock(&nf_conntrack_expect_lock);
  		exp = nf_ct_find_expectation(net, zone, tuple);
  		if (exp) {
  			pr_debug("conntrack: expectation arrives ct=%p exp=%p\n",
  				 ct, exp);
  			/* Welcome, Mr. Bond.  We've been expecting you... */
  			__set_bit(IPS_EXPECTED_BIT, &ct->status);
  			/* exp->master safe, refcnt bumped in nf_ct_find_expectation */
  			ct->master = exp->master;
  			if (exp->helper) {
  				help = nf_ct_helper_ext_add(ct, exp->helper,
  							    GFP_ATOMIC);
  				if (help)
  					rcu_assign_pointer(help->helper, exp->helper);
  			}
  
  #ifdef CONFIG_NF_CONNTRACK_MARK
  			ct->mark = exp->master->mark;
  #endif
  #ifdef CONFIG_NF_CONNTRACK_SECMARK
  			ct->secmark = exp->master->secmark;
  #endif
  			NF_CT_STAT_INC(net, expect_new);
  		}
  		spin_unlock(&nf_conntrack_expect_lock);
  	}
  	if (!exp) {
  		__nf_ct_try_assign_helper(ct, tmpl, GFP_ATOMIC);
  		NF_CT_STAT_INC(net, new);
  	}
  
  	/* Now it is inserted into the unconfirmed list, bump refcount */
  	nf_conntrack_get(&ct->ct_general);
  	nf_ct_add_to_unconfirmed_list(ct);
  
  	local_bh_enable();
  
  	if (exp) {
  		if (exp->expectfn)
  			exp->expectfn(ct, exp);
  		nf_ct_expect_put(exp);
  	}
  
  	return &ct->tuplehash[IP_CT_DIR_ORIGINAL];
  }
  
  /* On success, returns conntrack ptr, sets skb->nfct and ctinfo */
  static inline struct nf_conn *
  resolve_normal_ct(struct net *net, struct nf_conn *tmpl,
  		  struct sk_buff *skb,
  		  unsigned int dataoff,
  		  u_int16_t l3num,
  		  u_int8_t protonum,
  		  struct nf_conntrack_l3proto *l3proto,
  		  struct nf_conntrack_l4proto *l4proto,
  		  int *set_reply,
  		  enum ip_conntrack_info *ctinfo)
  {
  	struct nf_conntrack_tuple tuple;
  	struct nf_conntrack_tuple_hash *h;
  	struct nf_conn *ct;
  	u16 zone = tmpl ? nf_ct_zone(tmpl) : NF_CT_DEFAULT_ZONE;
  	u32 hash;
  
  	if (!nf_ct_get_tuple(skb, skb_network_offset(skb),
  			     dataoff, l3num, protonum, &tuple, l3proto,
  			     l4proto)) {
  		pr_debug("resolve_normal_ct: Can't get tuple\n");
  		return NULL;
  	}
  
  	/* look for tuple match */
  	hash = hash_conntrack_raw(&tuple, zone);
  	h = __nf_conntrack_find_get(net, zone, &tuple, hash);
  	if (!h) {
  		h = init_conntrack(net, tmpl, &tuple, l3proto, l4proto,
  				   skb, dataoff, hash);
  		if (!h)
  			return NULL;
  		if (IS_ERR(h))
  			return (void *)h;
  	}
  	ct = nf_ct_tuplehash_to_ctrack(h);
  
  	/* It exists; we have (non-exclusive) reference. */
  	if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY) {
  		*ctinfo = IP_CT_ESTABLISHED_REPLY;
  		/* Please set reply bit if this packet OK */
  		*set_reply = 1;
  	} else {
  		/* Once we've had two way comms, always ESTABLISHED. */
  		if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
  			pr_debug("nf_conntrack_in: normal packet for %p\n", ct);
  			*ctinfo = IP_CT_ESTABLISHED;
  		} else if (test_bit(IPS_EXPECTED_BIT, &ct->status)) {
  			pr_debug("nf_conntrack_in: related packet for %p\n",
  				 ct);
  			*ctinfo = IP_CT_RELATED;
  		} else {
  			pr_debug("nf_conntrack_in: new packet for %p\n", ct);
  			*ctinfo = IP_CT_NEW;
  		}
  		*set_reply = 0;
  	}
  	skb->nfct = &ct->ct_general;
  	skb->nfctinfo = *ctinfo;
  	return ct;
  }
  
  unsigned int
  nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum,
  		struct sk_buff *skb)
  {
  	struct nf_conn *ct, *tmpl = NULL;
  	enum ip_conntrack_info ctinfo;
  	struct nf_conntrack_l3proto *l3proto;
  	struct nf_conntrack_l4proto *l4proto;
  	unsigned int *timeouts;
  	unsigned int dataoff;
  	u_int8_t protonum;
  	int set_reply = 0;
  	int ret;
  
  	if (skb->nfct) {
  		/* Previously seen (loopback or untracked)?  Ignore. */
  		tmpl = (struct nf_conn *)skb->nfct;
  		if (!nf_ct_is_template(tmpl)) {
  			NF_CT_STAT_INC_ATOMIC(net, ignore);
  			return NF_ACCEPT;
  		}
  		skb->nfct = NULL;
  	}
  
  	/* rcu_read_lock()ed by nf_hook_slow */
  	l3proto = __nf_ct_l3proto_find(pf);
  	ret = l3proto->get_l4proto(skb, skb_network_offset(skb),
  				   &dataoff, &protonum);
  	if (ret <= 0) {
  		pr_debug("not prepared to track yet or error occurred\n");
  		NF_CT_STAT_INC_ATOMIC(net, error);
  		NF_CT_STAT_INC_ATOMIC(net, invalid);
  		ret = -ret;
  		goto out;
  	}
  
  	l4proto = __nf_ct_l4proto_find(pf, protonum);
  
  	/* It may be an special packet, error, unclean...
  	 * inverse of the return code tells to the netfilter
  	 * core what to do with the packet. */
  	if (l4proto->error != NULL) {
  		ret = l4proto->error(net, tmpl, skb, dataoff, &ctinfo,
  				     pf, hooknum);
  		if (ret <= 0) {
  			NF_CT_STAT_INC_ATOMIC(net, error);
  			NF_CT_STAT_INC_ATOMIC(net, invalid);
  			ret = -ret;
  			goto out;
  		}
  		/* ICMP[v6] protocol trackers may assign one conntrack. */
  		if (skb->nfct)
  			goto out;
  	}
  
  	ct = resolve_normal_ct(net, tmpl, skb, dataoff, pf, protonum,
  			       l3proto, l4proto, &set_reply, &ctinfo);
  	if (!ct) {
  		/* Not valid part of a connection */
  		NF_CT_STAT_INC_ATOMIC(net, invalid);
  		ret = NF_ACCEPT;
  		goto out;
  	}
  
  	if (IS_ERR(ct)) {
  		/* Too stressed to deal. */
  		NF_CT_STAT_INC_ATOMIC(net, drop);
  		ret = NF_DROP;
  		goto out;
  	}
  
  	NF_CT_ASSERT(skb->nfct);
  
  	/* Decide what timeout policy we want to apply to this flow. */
  	timeouts = nf_ct_timeout_lookup(net, ct, l4proto);
  
  	ret = l4proto->packet(ct, skb, dataoff, ctinfo, pf, hooknum, timeouts);
  	if (ret <= 0) {
  		/* Invalid: inverse of the return code tells
  		 * the netfilter core what to do */
  		pr_debug("nf_conntrack_in: Can't track with proto module\n");
  		nf_conntrack_put(skb->nfct);
  		skb->nfct = NULL;
  		NF_CT_STAT_INC_ATOMIC(net, invalid);
  		if (ret == -NF_DROP)
  			NF_CT_STAT_INC_ATOMIC(net, drop);
  		ret = -ret;
  		goto out;
  	}
  
  	if (set_reply && !test_and_set_bit(IPS_SEEN_REPLY_BIT, &ct->status))
  		nf_conntrack_event_cache(IPCT_REPLY, ct);
  out:
  	if (tmpl) {
  		/* Special case: we have to repeat this hook, assign the
  		 * template again to this packet. We assume that this packet
  		 * has no conntrack assigned. This is used by nf_ct_tcp. */
  		if (ret == NF_REPEAT)
  			skb->nfct = (struct nf_conntrack *)tmpl;
  		else
  			nf_ct_put(tmpl);
  	}
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(nf_conntrack_in);
  
  bool nf_ct_invert_tuplepr(struct nf_conntrack_tuple *inverse,
  			  const struct nf_conntrack_tuple *orig)
  {
  	bool ret;
  
  	rcu_read_lock();
  	ret = nf_ct_invert_tuple(inverse, orig,
  				 __nf_ct_l3proto_find(orig->src.l3num),
  				 __nf_ct_l4proto_find(orig->src.l3num,
  						      orig->dst.protonum));
  	rcu_read_unlock();
  	return ret;
  }
  EXPORT_SYMBOL_GPL(nf_ct_invert_tuplepr);
  
  /* Alter reply tuple (maybe alter helper).  This is for NAT, and is
     implicitly racy: see __nf_conntrack_confirm */
  void nf_conntrack_alter_reply(struct nf_conn *ct,
  			      const struct nf_conntrack_tuple *newreply)
  {
  	struct nf_conn_help *help = nfct_help(ct);
  
  	/* Should be unconfirmed, so not in hash table yet */
  	NF_CT_ASSERT(!nf_ct_is_confirmed(ct));
  
  	pr_debug("Altering reply tuple of %p to ", ct);
  	nf_ct_dump_tuple(newreply);
  
  	ct->tuplehash[IP_CT_DIR_REPLY].tuple = *newreply;
  	if (ct->master || (help && !hlist_empty(&help->expectations)))
  		return;
  
  	rcu_read_lock();
  	__nf_ct_try_assign_helper(ct, NULL, GFP_ATOMIC);
  	rcu_read_unlock();
  }
  EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply);
  
  /* Refresh conntrack for this many jiffies and do accounting if do_acct is 1 */
  void __nf_ct_refresh_acct(struct nf_conn *ct,
  			  enum ip_conntrack_info ctinfo,
  			  const struct sk_buff *skb,
  			  unsigned long extra_jiffies,
  			  int do_acct)
  {
  	NF_CT_ASSERT(ct->timeout.data == (unsigned long)ct);
  	NF_CT_ASSERT(skb);
  
  	/* Only update if this is not a fixed timeout */
  	if (test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status))
  		goto acct;
  
  	/* If not in hash table, timer will not be active yet */
  	if (!nf_ct_is_confirmed(ct)) {
  		ct->timeout.expires = extra_jiffies;
  	} else {
  		unsigned long newtime = jiffies + extra_jiffies;
  
  		/* Only update the timeout if the new timeout is at least
  		   HZ jiffies from the old timeout. Need del_timer for race
  		   avoidance (may already be dying). */
  		if (newtime - ct->timeout.expires >= HZ)
  			mod_timer_pending(&ct->timeout, newtime);
  	}
  
  acct:
  	if (do_acct) {
  		struct nf_conn_acct *acct;
  
  		acct = nf_conn_acct_find(ct);
  		if (acct) {
  			struct nf_conn_counter *counter = acct->counter;
  
  			atomic64_inc(&counter[CTINFO2DIR(ctinfo)].packets);
  			atomic64_add(skb->len, &counter[CTINFO2DIR(ctinfo)].bytes);
  		}
  	}
  }
  EXPORT_SYMBOL_GPL(__nf_ct_refresh_acct);
  
  bool __nf_ct_kill_acct(struct nf_conn *ct,
  		       enum ip_conntrack_info ctinfo,
  		       const struct sk_buff *skb,
  		       int do_acct)
  {
  	if (do_acct) {
  		struct nf_conn_acct *acct;
  
  		acct = nf_conn_acct_find(ct);
  		if (acct) {
  			struct nf_conn_counter *counter = acct->counter;
  
  			atomic64_inc(&counter[CTINFO2DIR(ctinfo)].packets);
  			atomic64_add(skb->len - skb_network_offset(skb),
  				     &counter[CTINFO2DIR(ctinfo)].bytes);
  		}
  	}
  
  	if (del_timer(&ct->timeout)) {
  		ct->timeout.function((unsigned long)ct);
  		return true;
  	}
  	return false;
  }
  EXPORT_SYMBOL_GPL(__nf_ct_kill_acct);
  
  #ifdef CONFIG_NF_CONNTRACK_ZONES
  static struct nf_ct_ext_type nf_ct_zone_extend __read_mostly = {
  	.len	= sizeof(struct nf_conntrack_zone),
  	.align	= __alignof__(struct nf_conntrack_zone),
  	.id	= NF_CT_EXT_ZONE,
  };
  #endif
  
  #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
  
  #include <linux/netfilter/nfnetlink.h>
  #include <linux/netfilter/nfnetlink_conntrack.h>
  #include <linux/mutex.h>
  
  /* Generic function for tcp/udp/sctp/dccp and alike. This needs to be
   * in ip_conntrack_core, since we don't want the protocols to autoload
   * or depend on ctnetlink */
  int nf_ct_port_tuple_to_nlattr(struct sk_buff *skb,
  			       const struct nf_conntrack_tuple *tuple)
  {
  	if (nla_put_be16(skb, CTA_PROTO_SRC_PORT, tuple->src.u.tcp.port) ||
  	    nla_put_be16(skb, CTA_PROTO_DST_PORT, tuple->dst.u.tcp.port))
  		goto nla_put_failure;
  	return 0;
  
  nla_put_failure:
  	return -1;
  }
  EXPORT_SYMBOL_GPL(nf_ct_port_tuple_to_nlattr);
  
  const struct nla_policy nf_ct_port_nla_policy[CTA_PROTO_MAX+1] = {
  	[CTA_PROTO_SRC_PORT]  = { .type = NLA_U16 },
  	[CTA_PROTO_DST_PORT]  = { .type = NLA_U16 },
  };
  EXPORT_SYMBOL_GPL(nf_ct_port_nla_policy);
  
  int nf_ct_port_nlattr_to_tuple(struct nlattr *tb[],
  			       struct nf_conntrack_tuple *t)
  {
  	if (!tb[CTA_PROTO_SRC_PORT] || !tb[CTA_PROTO_DST_PORT])
  		return -EINVAL;
  
  	t->src.u.tcp.port = nla_get_be16(tb[CTA_PROTO_SRC_PORT]);
  	t->dst.u.tcp.port = nla_get_be16(tb[CTA_PROTO_DST_PORT]);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(nf_ct_port_nlattr_to_tuple);
  
  int nf_ct_port_nlattr_tuple_size(void)
  {
  	return nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
  }
  EXPORT_SYMBOL_GPL(nf_ct_port_nlattr_tuple_size);
  #endif
  
  /* Used by ipt_REJECT and ip6t_REJECT. */
  static void nf_conntrack_attach(struct sk_buff *nskb, const struct sk_buff *skb)
  {
  	struct nf_conn *ct;
  	enum ip_conntrack_info ctinfo;
  
  	/* This ICMP is in reverse direction to the packet which caused it */
  	ct = nf_ct_get(skb, &ctinfo);
  	if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL)
  		ctinfo = IP_CT_RELATED_REPLY;
  	else
  		ctinfo = IP_CT_RELATED;
  
  	/* Attach to new skbuff, and increment count */
  	nskb->nfct = &ct->ct_general;
  	nskb->nfctinfo = ctinfo;
  	nf_conntrack_get(nskb->nfct);
  }
  
  /* Bring out ya dead! */
  static struct nf_conn *
  get_next_corpse(struct net *net, int (*iter)(struct nf_conn *i, void *data),
  		void *data, unsigned int *bucket)
  {
  	struct nf_conntrack_tuple_hash *h;
  	struct nf_conn *ct;
  	struct hlist_nulls_node *n;
  	int cpu;
  	spinlock_t *lockp;
  
  	for (; *bucket < net->ct.htable_size; (*bucket)++) {
  		lockp = &nf_conntrack_locks[*bucket % CONNTRACK_LOCKS];
  		local_bh_disable();
  		spin_lock(lockp);
  		if (*bucket < net->ct.htable_size) {
  			hlist_nulls_for_each_entry(h, n, &net->ct.hash[*bucket], hnnode) {
  				if (NF_CT_DIRECTION(h) != IP_CT_DIR_ORIGINAL)
  					continue;
  				ct = nf_ct_tuplehash_to_ctrack(h);
  				if (iter(ct, data))
  					goto found;
  			}
  		}
  		spin_unlock(lockp);
  		local_bh_enable();
  	}
  
  	for_each_possible_cpu(cpu) {
  		struct ct_pcpu *pcpu = per_cpu_ptr(net->ct.pcpu_lists, cpu);
  
  		spin_lock_bh(&pcpu->lock);
  		hlist_nulls_for_each_entry(h, n, &pcpu->unconfirmed, hnnode) {
  			ct = nf_ct_tuplehash_to_ctrack(h);
  			if (iter(ct, data))
  				set_bit(IPS_DYING_BIT, &ct->status);
  		}
  		spin_unlock_bh(&pcpu->lock);
  	}
  	return NULL;
  found:
  	atomic_inc(&ct->ct_general.use);
  	spin_unlock(lockp);
  	local_bh_enable();
  	return ct;
  }
  
  void nf_ct_iterate_cleanup(struct net *net,
  			   int (*iter)(struct nf_conn *i, void *data),
  			   void *data, u32 portid, int report)
  {
  	struct nf_conn *ct;
  	unsigned int bucket = 0;
  
  	while ((ct = get_next_corpse(net, iter, data, &bucket)) != NULL) {
  		/* Time to push up daises... */
  		if (del_timer(&ct->timeout))
  			nf_ct_delete(ct, portid, report);
  
  		/* ... else the timer will get him soon. */
  
  		nf_ct_put(ct);
  	}
  }
  EXPORT_SYMBOL_GPL(nf_ct_iterate_cleanup);
  
  static int kill_all(struct nf_conn *i, void *data)
  {
  	return 1;
  }
  
  void nf_ct_free_hashtable(void *hash, unsigned int size)
  {
  	if (is_vmalloc_addr(hash))
  		vfree(hash);
  	else
  		free_pages((unsigned long)hash,
  			   get_order(sizeof(struct hlist_head) * size));
  }
  EXPORT_SYMBOL_GPL(nf_ct_free_hashtable);
  
  static int untrack_refs(void)
  {
  	int cnt = 0, cpu;
  
  	for_each_possible_cpu(cpu) {
  		struct nf_conn *ct = &per_cpu(nf_conntrack_untracked, cpu);
  
  		cnt += atomic_read(&ct->ct_general.use) - 1;
  	}
  	return cnt;
  }
  
  void nf_conntrack_cleanup_start(void)
  {
  	RCU_INIT_POINTER(ip_ct_attach, NULL);
  }
  
  void nf_conntrack_cleanup_end(void)
  {
  	RCU_INIT_POINTER(nf_ct_destroy, NULL);
  	while (untrack_refs() > 0)
  		schedule();
  
  #ifdef CONFIG_NF_CONNTRACK_ZONES
  	nf_ct_extend_unregister(&nf_ct_zone_extend);
  #endif
  	nf_conntrack_proto_fini();
  	nf_conntrack_seqadj_fini();
  	nf_conntrack_labels_fini();
  	nf_conntrack_helper_fini();
  	nf_conntrack_timeout_fini();
  	nf_conntrack_ecache_fini();
  	nf_conntrack_tstamp_fini();
  	nf_conntrack_acct_fini();
  	nf_conntrack_expect_fini();
  }
  
  /*
   * Mishearing the voices in his head, our hero wonders how he's
   * supposed to kill the mall.
   */
  void nf_conntrack_cleanup_net(struct net *net)
  {
  	LIST_HEAD(single);
  
  	list_add(&net->exit_list, &single);
  	nf_conntrack_cleanup_net_list(&single);
  }
  
  void nf_conntrack_cleanup_net_list(struct list_head *net_exit_list)
  {
  	int busy;
  	struct net *net;
  
  	/*
  	 * This makes sure all current packets have passed through
  	 *  netfilter framework.  Roll on, two-stage module
  	 *  delete...
  	 */
  	synchronize_net();
  i_see_dead_people:
  	busy = 0;
  	list_for_each_entry(net, net_exit_list, exit_list) {
  		nf_ct_iterate_cleanup(net, kill_all, NULL, 0, 0);
  		if (atomic_read(&net->ct.count) != 0)
  			busy = 1;
  	}
  	if (busy) {
  		schedule();
  		goto i_see_dead_people;
  	}
  
  	list_for_each_entry(net, net_exit_list, exit_list) {
  		nf_ct_free_hashtable(net->ct.hash, net->ct.htable_size);
  		nf_conntrack_proto_pernet_fini(net);
  		nf_conntrack_helper_pernet_fini(net);
  		nf_conntrack_ecache_pernet_fini(net);
  		nf_conntrack_tstamp_pernet_fini(net);
  		nf_conntrack_acct_pernet_fini(net);
  		nf_conntrack_expect_pernet_fini(net);
  		kmem_cache_destroy(net->ct.nf_conntrack_cachep);
  		kfree(net->ct.slabname);
  		free_percpu(net->ct.stat);
  		free_percpu(net->ct.pcpu_lists);
  	}
  }
  
  void *nf_ct_alloc_hashtable(unsigned int *sizep, int nulls)
  {
  	struct hlist_nulls_head *hash;
  	unsigned int nr_slots, i;
  	size_t sz;
  
  	BUILD_BUG_ON(sizeof(struct hlist_nulls_head) != sizeof(struct hlist_head));
  	nr_slots = *sizep = roundup(*sizep, PAGE_SIZE / sizeof(struct hlist_nulls_head));
  	sz = nr_slots * sizeof(struct hlist_nulls_head);
  	hash = (void *)__get_free_pages(GFP_KERNEL | __GFP_NOWARN | __GFP_ZERO,
  					get_order(sz));
  	if (!hash)
  		hash = vzalloc(sz);
  
  	if (hash && nulls)
  		for (i = 0; i < nr_slots; i++)
  			INIT_HLIST_NULLS_HEAD(&hash[i], i);
  
  	return hash;
  }
  EXPORT_SYMBOL_GPL(nf_ct_alloc_hashtable);
  
  int nf_conntrack_set_hashsize(const char *val, struct kernel_param *kp)
  {
  	int i, bucket, rc;
  	unsigned int hashsize, old_size;
  	struct hlist_nulls_head *hash, *old_hash;
  	struct nf_conntrack_tuple_hash *h;
  	struct nf_conn *ct;
  
  	if (current->nsproxy->net_ns != &init_net)
  		return -EOPNOTSUPP;
  
  	/* On boot, we can set this without any fancy locking. */
  	if (!nf_conntrack_htable_size)
  		return param_set_uint(val, kp);
  
  	rc = kstrtouint(val, 0, &hashsize);
  	if (rc)
  		return rc;
  	if (!hashsize)
  		return -EINVAL;
  
  	hash = nf_ct_alloc_hashtable(&hashsize, 1);
  	if (!hash)
  		return -ENOMEM;
  
  	local_bh_disable();
  	nf_conntrack_all_lock();
  	write_seqcount_begin(&init_net.ct.generation);
  
  	/* Lookups in the old hash might happen in parallel, which means we
  	 * might get false negatives during connection lookup. New connections
  	 * created because of a false negative won't make it into the hash
  	 * though since that required taking the locks.
  	 */
  
  	for (i = 0; i < init_net.ct.htable_size; i++) {
  		while (!hlist_nulls_empty(&init_net.ct.hash[i])) {
  			h = hlist_nulls_entry(init_net.ct.hash[i].first,
  					struct nf_conntrack_tuple_hash, hnnode);
  			ct = nf_ct_tuplehash_to_ctrack(h);
  			hlist_nulls_del_rcu(&h->hnnode);
  			bucket = __hash_conntrack(&h->tuple, nf_ct_zone(ct),
  						  hashsize);
  			hlist_nulls_add_head_rcu(&h->hnnode, &hash[bucket]);
  		}
  	}
  	old_size = init_net.ct.htable_size;
  	old_hash = init_net.ct.hash;
  
  	init_net.ct.htable_size = nf_conntrack_htable_size = hashsize;
  	init_net.ct.hash = hash;
  
  	write_seqcount_end(&init_net.ct.generation);
  	nf_conntrack_all_unlock();
  	local_bh_enable();
  
  	nf_ct_free_hashtable(old_hash, old_size);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(nf_conntrack_set_hashsize);
  
  module_param_call(hashsize, nf_conntrack_set_hashsize, param_get_uint,
  		  &nf_conntrack_htable_size, 0600);
  
  void nf_ct_untracked_status_or(unsigned long bits)
  {
  	int cpu;
  
  	for_each_possible_cpu(cpu)
  		per_cpu(nf_conntrack_untracked, cpu).status |= bits;
  }
  EXPORT_SYMBOL_GPL(nf_ct_untracked_status_or);
  
  int nf_conntrack_init_start(void)
  {
  	int max_factor = 8;
  	int i, ret, cpu;
  
  	for (i = 0; i < CONNTRACK_LOCKS; i++)
  		spin_lock_init(&nf_conntrack_locks[i]);
  
  	if (!nf_conntrack_htable_size) {
  		/* Idea from tcp.c: use 1/16384 of memory.
  		 * On i386: 32MB machine has 512 buckets.
  		 * >= 1GB machines have 16384 buckets.
  		 * >= 4GB machines have 65536 buckets.
  		 */
  		nf_conntrack_htable_size
  			= (((totalram_pages << PAGE_SHIFT) / 16384)
  			   / sizeof(struct hlist_head));
  		if (totalram_pages > (4 * (1024 * 1024 * 1024 / PAGE_SIZE)))
  			nf_conntrack_htable_size = 65536;
  		else if (totalram_pages > (1024 * 1024 * 1024 / PAGE_SIZE))
  			nf_conntrack_htable_size = 16384;
  		if (nf_conntrack_htable_size < 32)
  			nf_conntrack_htable_size = 32;
  
  		/* Use a max. factor of four by default to get the same max as
  		 * with the old struct list_heads. When a table size is given
  		 * we use the old value of 8 to avoid reducing the max.
  		 * entries. */
  		max_factor = 4;
  	}
  	nf_conntrack_max = max_factor * nf_conntrack_htable_size;
  
  	printk(KERN_INFO "nf_conntrack version %s (%u buckets, %d max)\n",
  	       NF_CONNTRACK_VERSION, nf_conntrack_htable_size,
  	       nf_conntrack_max);
  
  	ret = nf_conntrack_expect_init();
  	if (ret < 0)
  		goto err_expect;
  
  	ret = nf_conntrack_acct_init();
  	if (ret < 0)
  		goto err_acct;
  
  	ret = nf_conntrack_tstamp_init();
  	if (ret < 0)
  		goto err_tstamp;
  
  	ret = nf_conntrack_ecache_init();
  	if (ret < 0)
  		goto err_ecache;
  
  	ret = nf_conntrack_timeout_init();
  	if (ret < 0)
  		goto err_timeout;
  
  	ret = nf_conntrack_helper_init();
  	if (ret < 0)
  		goto err_helper;
  
  	ret = nf_conntrack_labels_init();
  	if (ret < 0)
  		goto err_labels;
  
  	ret = nf_conntrack_seqadj_init();
  	if (ret < 0)
  		goto err_seqadj;
  
  #ifdef CONFIG_NF_CONNTRACK_ZONES
  	ret = nf_ct_extend_register(&nf_ct_zone_extend);
  	if (ret < 0)
  		goto err_extend;
  #endif
  	ret = nf_conntrack_proto_init();
  	if (ret < 0)
  		goto err_proto;
  
  	/* Set up fake conntrack: to never be deleted, not in any hashes */
  	for_each_possible_cpu(cpu) {
  		struct nf_conn *ct = &per_cpu(nf_conntrack_untracked, cpu);
  		write_pnet(&ct->ct_net, &init_net);
  		atomic_set(&ct->ct_general.use, 1);
  	}
  	/*  - and look it like as a confirmed connection */
  	nf_ct_untracked_status_or(IPS_CONFIRMED | IPS_UNTRACKED);
  	return 0;
  
  err_proto:
  #ifdef CONFIG_NF_CONNTRACK_ZONES
  	nf_ct_extend_unregister(&nf_ct_zone_extend);
  err_extend:
  #endif
  	nf_conntrack_seqadj_fini();
  err_seqadj:
  	nf_conntrack_labels_fini();
  err_labels:
  	nf_conntrack_helper_fini();
  err_helper:
  	nf_conntrack_timeout_fini();
  err_timeout:
  	nf_conntrack_ecache_fini();
  err_ecache:
  	nf_conntrack_tstamp_fini();
  err_tstamp:
  	nf_conntrack_acct_fini();
  err_acct:
  	nf_conntrack_expect_fini();
  err_expect:
  	return ret;
  }
  
  void nf_conntrack_init_end(void)
  {
  	/* For use by REJECT target */
  	RCU_INIT_POINTER(ip_ct_attach, nf_conntrack_attach);
  	RCU_INIT_POINTER(nf_ct_destroy, destroy_conntrack);
  }
  
  /*
   * We need to use special "null" values, not used in hash table
   */
  #define UNCONFIRMED_NULLS_VAL	((1<<30)+0)
  #define DYING_NULLS_VAL		((1<<30)+1)
  #define TEMPLATE_NULLS_VAL	((1<<30)+2)
  
  int nf_conntrack_init_net(struct net *net)
  {
  	int ret = -ENOMEM;
  	int cpu;
  
  	atomic_set(&net->ct.count, 0);
  	seqcount_init(&net->ct.generation);
  
  	net->ct.pcpu_lists = alloc_percpu(struct ct_pcpu);
  	if (!net->ct.pcpu_lists)
  		goto err_stat;
  
  	for_each_possible_cpu(cpu) {
  		struct ct_pcpu *pcpu = per_cpu_ptr(net->ct.pcpu_lists, cpu);
  
  		spin_lock_init(&pcpu->lock);
  		INIT_HLIST_NULLS_HEAD(&pcpu->unconfirmed, UNCONFIRMED_NULLS_VAL);
  		INIT_HLIST_NULLS_HEAD(&pcpu->dying, DYING_NULLS_VAL);
  	}
  
  	net->ct.stat = alloc_percpu(struct ip_conntrack_stat);
  	if (!net->ct.stat)
  		goto err_pcpu_lists;
  
  	net->ct.slabname = kasprintf(GFP_KERNEL, "nf_conntrack_%p", net);
  	if (!net->ct.slabname)
  		goto err_slabname;
  
  	net->ct.nf_conntrack_cachep = kmem_cache_create(net->ct.slabname,
  							sizeof(struct nf_conn), 0,
  							SLAB_DESTROY_BY_RCU, NULL);
  	if (!net->ct.nf_conntrack_cachep) {
  		printk(KERN_ERR "Unable to create nf_conn slab cache\n");
  		goto err_cache;
  	}
  
  	net->ct.htable_size = nf_conntrack_htable_size;
  	net->ct.hash = nf_ct_alloc_hashtable(&net->ct.htable_size, 1);
  	if (!net->ct.hash) {
  		printk(KERN_ERR "Unable to create nf_conntrack_hash\n");
  		goto err_hash;
  	}
  	ret = nf_conntrack_expect_pernet_init(net);
  	if (ret < 0)
  		goto err_expect;
  	ret = nf_conntrack_acct_pernet_init(net);
  	if (ret < 0)
  		goto err_acct;
  	ret = nf_conntrack_tstamp_pernet_init(net);
  	if (ret < 0)
  		goto err_tstamp;
  	ret = nf_conntrack_ecache_pernet_init(net);
  	if (ret < 0)
  		goto err_ecache;
  	ret = nf_conntrack_helper_pernet_init(net);
  	if (ret < 0)
  		goto err_helper;
  	ret = nf_conntrack_proto_pernet_init(net);
  	if (ret < 0)
  		goto err_proto;
  	return 0;
  
  err_proto:
  	nf_conntrack_helper_pernet_fini(net);
  err_helper:
  	nf_conntrack_ecache_pernet_fini(net);
  err_ecache:
  	nf_conntrack_tstamp_pernet_fini(net);
  err_tstamp:
  	nf_conntrack_acct_pernet_fini(net);
  err_acct:
  	nf_conntrack_expect_pernet_fini(net);
  err_expect:
  	nf_ct_free_hashtable(net->ct.hash, net->ct.htable_size);
  err_hash:
  	kmem_cache_destroy(net->ct.nf_conntrack_cachep);
  err_cache:
  	kfree(net->ct.slabname);
  err_slabname:
  	free_percpu(net->ct.stat);
  err_pcpu_lists:
  	free_percpu(net->ct.pcpu_lists);
  err_stat:
  	return ret;
  }
  