net/netfilter/nf_conntrack_proto.c - arm/linux - Git at Google

 /* L3/L4 protocol support for nf_conntrack. */

 /* (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) 2006-2012 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/slab.h>
 #include <linux/mutex.h>
 #include <linux/vmalloc.h>
 #include <linux/stddef.h>
 #include <linux/err.h>
 #include <linux/percpu.h>
 #include <linux/notifier.h>
 #include <linux/kernel.h>
 #include <linux/netdevice.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_core.h>

 static struct nf_conntrack_l4proto __rcu **nf_ct_protos[NFPROTO_NUMPROTO] __read_mostly;
 struct nf_conntrack_l3proto __rcu *nf_ct_l3protos[NFPROTO_NUMPROTO] __read_mostly;
 EXPORT_SYMBOL_GPL(nf_ct_l3protos);

 static DEFINE_MUTEX(nf_ct_proto_mutex);

 #ifdef CONFIG_SYSCTL
 static int
 nf_ct_register_sysctl(struct net *net,
 		      struct ctl_table_header **header,
 		      const char *path,
 		      struct ctl_table *table)
 {
 	if (*header == NULL) {
 		*header = register_net_sysctl(net, path, table);
 		if (*header == NULL)
 			return -ENOMEM;
 	}

 	return 0;
 }

 static void
 nf_ct_unregister_sysctl(struct ctl_table_header **header,
 			struct ctl_table **table,
 			unsigned int users)
 {
 	if (users > 0)
 		return;

 	unregister_net_sysctl_table(*header);
 	kfree(*table);
 	*header = NULL;
 	*table = NULL;
 }
 #endif

 const struct nf_conntrack_l4proto *
 __nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
 {
 	if (unlikely(l3proto >= NFPROTO_NUMPROTO || nf_ct_protos[l3proto] == NULL))
 		return &nf_conntrack_l4proto_generic;

 	return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
 }
 EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);

 /* this is guaranteed to always return a valid protocol helper, since
  * it falls back to generic_protocol */
 const struct nf_conntrack_l3proto *
 nf_ct_l3proto_find_get(u_int16_t l3proto)
 {
 	struct nf_conntrack_l3proto *p;

 	rcu_read_lock();
 	p = __nf_ct_l3proto_find(l3proto);
 	if (!try_module_get(p->me))
 		p = &nf_conntrack_l3proto_generic;
 	rcu_read_unlock();

 	return p;
 }
 EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);

 int
 nf_ct_l3proto_try_module_get(unsigned short l3proto)
 {
 	const struct nf_conntrack_l3proto *p;
 	int ret;

 retry:	p = nf_ct_l3proto_find_get(l3proto);
 	if (p == &nf_conntrack_l3proto_generic) {
 		ret = request_module("nf_conntrack-%d", l3proto);
 		if (!ret)
 			goto retry;

 		return -EPROTOTYPE;
 	}

 	return 0;
 }
 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);

 void nf_ct_l3proto_module_put(unsigned short l3proto)
 {
 	struct nf_conntrack_l3proto *p;

 	/* rcu_read_lock not necessary since the caller holds a reference, but
 	 * taken anyways to avoid lockdep warnings in __nf_ct_l3proto_find()
 	 */
 	rcu_read_lock();
 	p = __nf_ct_l3proto_find(l3proto);
 	module_put(p->me);
 	rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);

 int nf_ct_netns_get(struct net *net, u8 nfproto)
 {
 	const struct nf_conntrack_l3proto *l3proto;
 	int ret;

 	might_sleep();

 	ret = nf_ct_l3proto_try_module_get(nfproto);
 	if (ret < 0)
 		return ret;

 	/* we already have a reference, can't fail */
 	rcu_read_lock();
 	l3proto = __nf_ct_l3proto_find(nfproto);
 	rcu_read_unlock();

 	if (!l3proto->net_ns_get)
 		return 0;

 	ret = l3proto->net_ns_get(net);
 	if (ret < 0)
 		nf_ct_l3proto_module_put(nfproto);

 	return ret;
 }
 EXPORT_SYMBOL_GPL(nf_ct_netns_get);

 void nf_ct_netns_put(struct net *net, u8 nfproto)
 {
 	const struct nf_conntrack_l3proto *l3proto;

 	might_sleep();

 	/* same as nf_conntrack_netns_get(), reference assumed */
 	rcu_read_lock();
 	l3proto = __nf_ct_l3proto_find(nfproto);
 	rcu_read_unlock();

 	if (WARN_ON(!l3proto))
 		return;

 	if (l3proto->net_ns_put)
 		l3proto->net_ns_put(net);

 	nf_ct_l3proto_module_put(nfproto);
 }
 EXPORT_SYMBOL_GPL(nf_ct_netns_put);

 const struct nf_conntrack_l4proto *
 nf_ct_l4proto_find_get(u_int16_t l3num, u_int8_t l4num)
 {
 	const struct nf_conntrack_l4proto *p;

 	rcu_read_lock();
 	p = __nf_ct_l4proto_find(l3num, l4num);
 	if (!try_module_get(p->me))
 		p = &nf_conntrack_l4proto_generic;
 	rcu_read_unlock();

 	return p;
 }
 EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);

 void nf_ct_l4proto_put(const struct nf_conntrack_l4proto *p)
 {
 	module_put(p->me);
 }
 EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);

 static int kill_l3proto(struct nf_conn *i, void *data)
 {
 	return nf_ct_l3num(i) == ((const struct nf_conntrack_l3proto *)data)->l3proto;
 }

 static int kill_l4proto(struct nf_conn *i, void *data)
 {
 	const struct nf_conntrack_l4proto *l4proto;
 	l4proto = data;
 	return nf_ct_protonum(i) == l4proto->l4proto &&
 	       nf_ct_l3num(i) == l4proto->l3proto;
 }

 int nf_ct_l3proto_register(const struct nf_conntrack_l3proto *proto)
 {
 	int ret = 0;
 	struct nf_conntrack_l3proto *old;

 	if (proto->l3proto >= NFPROTO_NUMPROTO)
 		return -EBUSY;
 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 	if (proto->tuple_to_nlattr && proto->nla_size == 0)
 		return -EINVAL;
 #endif
 	mutex_lock(&nf_ct_proto_mutex);
 	old = rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
 					lockdep_is_held(&nf_ct_proto_mutex));
 	if (old != &nf_conntrack_l3proto_generic) {
 		ret = -EBUSY;
 		goto out_unlock;
 	}

 	rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);

 out_unlock:
 	mutex_unlock(&nf_ct_proto_mutex);
 	return ret;

 }
 EXPORT_SYMBOL_GPL(nf_ct_l3proto_register);

 void nf_ct_l3proto_unregister(const struct nf_conntrack_l3proto *proto)
 {
 	BUG_ON(proto->l3proto >= NFPROTO_NUMPROTO);

 	mutex_lock(&nf_ct_proto_mutex);
 	BUG_ON(rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
 					 lockdep_is_held(&nf_ct_proto_mutex)
 					 ) != proto);
 	rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
 			   &nf_conntrack_l3proto_generic);
 	mutex_unlock(&nf_ct_proto_mutex);

 	synchronize_rcu();
 	/* Remove all contrack entries for this protocol */
 	nf_ct_iterate_destroy(kill_l3proto, (void*)proto);
 }
 EXPORT_SYMBOL_GPL(nf_ct_l3proto_unregister);

 static struct nf_proto_net *nf_ct_l4proto_net(struct net *net,
 				const struct nf_conntrack_l4proto *l4proto)
 {
 	if (l4proto->get_net_proto) {
 		/* statically built-in protocols use static per-net */
 		return l4proto->get_net_proto(net);
 	} else if (l4proto->net_id) {
 		/* ... and loadable protocols use dynamic per-net */
 		return net_generic(net, *l4proto->net_id);
 	}
 	return NULL;
 }

 static
 int nf_ct_l4proto_register_sysctl(struct net *net,
 				  struct nf_proto_net *pn,
 				  const struct nf_conntrack_l4proto *l4proto)
 {
 	int err = 0;

 #ifdef CONFIG_SYSCTL
 	if (pn->ctl_table != NULL) {
 		err = nf_ct_register_sysctl(net,
 					    &pn->ctl_table_header,
 					    "net/netfilter",
 					    pn->ctl_table);
 		if (err < 0) {
 			if (!pn->users) {
 				kfree(pn->ctl_table);
 				pn->ctl_table = NULL;
 			}
 		}
 	}
 #endif /* CONFIG_SYSCTL */
 	return err;
 }

 static
 void nf_ct_l4proto_unregister_sysctl(struct net *net,
 				struct nf_proto_net *pn,
 				const struct nf_conntrack_l4proto *l4proto)
 {
 #ifdef CONFIG_SYSCTL
 	if (pn->ctl_table_header != NULL)
 		nf_ct_unregister_sysctl(&pn->ctl_table_header,
 					&pn->ctl_table,
 					pn->users);
 #endif /* CONFIG_SYSCTL */
 }

 /* FIXME: Allow NULL functions and sub in pointers to generic for
    them. --RR */
 int nf_ct_l4proto_register_one(struct nf_conntrack_l4proto *l4proto)
 {
 	int ret = 0;

 	if (l4proto->l3proto >= ARRAY_SIZE(nf_ct_protos))
 		return -EBUSY;

 	if ((l4proto->to_nlattr && !l4proto->nlattr_size) ||
 	    (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
 		return -EINVAL;

 	mutex_lock(&nf_ct_proto_mutex);
 	if (!nf_ct_protos[l4proto->l3proto]) {
 		/* l3proto may be loaded latter. */
 		struct nf_conntrack_l4proto __rcu **proto_array;
 		int i;

 		proto_array = kmalloc(MAX_NF_CT_PROTO *
 				      sizeof(struct nf_conntrack_l4proto *),
 				      GFP_KERNEL);
 		if (proto_array == NULL) {
 			ret = -ENOMEM;
 			goto out_unlock;
 		}

 		for (i = 0; i < MAX_NF_CT_PROTO; i++)
 			RCU_INIT_POINTER(proto_array[i],
 					 &nf_conntrack_l4proto_generic);

 		/* Before making proto_array visible to lockless readers,
 		 * we must make sure its content is committed to memory.
 		 */
 		smp_wmb();

 		nf_ct_protos[l4proto->l3proto] = proto_array;
 	} else if (rcu_dereference_protected(
 			nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 			lockdep_is_held(&nf_ct_proto_mutex)
 			) != &nf_conntrack_l4proto_generic) {
 		ret = -EBUSY;
 		goto out_unlock;
 	}

 	l4proto->nla_size = 0;
 	if (l4proto->nlattr_size)
 		l4proto->nla_size += l4proto->nlattr_size();
 	if (l4proto->nlattr_tuple_size)
 		l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();

 	rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 			   l4proto);
 out_unlock:
 	mutex_unlock(&nf_ct_proto_mutex);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register_one);

 int nf_ct_l4proto_pernet_register_one(struct net *net,
 				const struct nf_conntrack_l4proto *l4proto)
 {
 	int ret = 0;
 	struct nf_proto_net *pn = NULL;

 	if (l4proto->init_net) {
 		ret = l4proto->init_net(net, l4proto->l3proto);
 		if (ret < 0)
 			goto out;
 	}

 	pn = nf_ct_l4proto_net(net, l4proto);
 	if (pn == NULL)
 		goto out;

 	ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
 	if (ret < 0)
 		goto out;

 	pn->users++;
 out:
 	return ret;
 }
 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register_one);

 static void __nf_ct_l4proto_unregister_one(const struct nf_conntrack_l4proto *l4proto)

 {
 	BUG_ON(l4proto->l3proto >= ARRAY_SIZE(nf_ct_protos));

 	BUG_ON(rcu_dereference_protected(
 			nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 			lockdep_is_held(&nf_ct_proto_mutex)
 			) != l4proto);
 	rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 			   &nf_conntrack_l4proto_generic);
 }

 void nf_ct_l4proto_unregister_one(const struct nf_conntrack_l4proto *l4proto)
 {
 	mutex_lock(&nf_ct_proto_mutex);
 	__nf_ct_l4proto_unregister_one(l4proto);
 	mutex_unlock(&nf_ct_proto_mutex);

 	synchronize_rcu();
 }
 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister_one);

 void nf_ct_l4proto_pernet_unregister_one(struct net *net,
 				const struct nf_conntrack_l4proto *l4proto)
 {
 	struct nf_proto_net *pn = nf_ct_l4proto_net(net, l4proto);

 	if (pn == NULL)
 		return;

 	pn->users--;
 	nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
 }
 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister_one);

 int nf_ct_l4proto_register(struct nf_conntrack_l4proto *l4proto[],
 			   unsigned int num_proto)
 {
 	int ret = -EINVAL, ver;
 	unsigned int i;

 	for (i = 0; i < num_proto; i++) {
 		ret = nf_ct_l4proto_register_one(l4proto[i]);
 		if (ret < 0)
 			break;
 	}
 	if (i != num_proto) {
 		ver = l4proto[i]->l3proto == PF_INET6 ? 6 : 4;
 		pr_err("nf_conntrack_ipv%d: can't register l4 %d proto.\n",
 		       ver, l4proto[i]->l4proto);
 		nf_ct_l4proto_unregister(l4proto, i);
 	}
 	return ret;
 }
 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register);

 int nf_ct_l4proto_pernet_register(struct net *net,
 				  struct nf_conntrack_l4proto *const l4proto[],
 				  unsigned int num_proto)
 {
 	int ret = -EINVAL;
 	unsigned int i;

 	for (i = 0; i < num_proto; i++) {
 		ret = nf_ct_l4proto_pernet_register_one(net, l4proto[i]);
 		if (ret < 0)
 			break;
 	}
 	if (i != num_proto) {
 		pr_err("nf_conntrack_proto_%d %d: pernet registration failed\n",
 		       l4proto[i]->l4proto,
 		       l4proto[i]->l3proto == PF_INET6 ? 6 : 4);
 		nf_ct_l4proto_pernet_unregister(net, l4proto, i);
 	}
 	return ret;
 }
 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register);

 void nf_ct_l4proto_unregister(struct nf_conntrack_l4proto *l4proto[],
 			      unsigned int num_proto)
 {
 	mutex_lock(&nf_ct_proto_mutex);
 	while (num_proto-- != 0)
 		__nf_ct_l4proto_unregister_one(l4proto[num_proto]);
 	mutex_unlock(&nf_ct_proto_mutex);

 	synchronize_net();
 	/* Remove all contrack entries for this protocol */
 	nf_ct_iterate_destroy(kill_l4proto, l4proto);
 }
 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister);

 void nf_ct_l4proto_pernet_unregister(struct net *net,
 				struct nf_conntrack_l4proto *const l4proto[],
 				unsigned int num_proto)
 {
 	while (num_proto-- != 0)
 		nf_ct_l4proto_pernet_unregister_one(net, l4proto[num_proto]);
 }
 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister);

 int nf_conntrack_proto_pernet_init(struct net *net)
 {
 	int err;
 	struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 					&nf_conntrack_l4proto_generic);

 	err = nf_conntrack_l4proto_generic.init_net(net,
 					nf_conntrack_l4proto_generic.l3proto);
 	if (err < 0)
 		return err;
 	err = nf_ct_l4proto_register_sysctl(net,
 					    pn,
 					    &nf_conntrack_l4proto_generic);
 	if (err < 0)
 		return err;

 	pn->users++;
 	return 0;
 }

 void nf_conntrack_proto_pernet_fini(struct net *net)
 {
 	struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 					&nf_conntrack_l4proto_generic);

 	pn->users--;
 	nf_ct_l4proto_unregister_sysctl(net,
 					pn,
 					&nf_conntrack_l4proto_generic);
 }

 int nf_conntrack_proto_init(void)
 {
 	unsigned int i;
 	for (i = 0; i < NFPROTO_NUMPROTO; i++)
 		rcu_assign_pointer(nf_ct_l3protos[i],
 				   &nf_conntrack_l3proto_generic);
 	return 0;
 }

 void nf_conntrack_proto_fini(void)
 {
 	unsigned int i;
 	/* free l3proto protocol tables */
 	for (i = 0; i < ARRAY_SIZE(nf_ct_protos); i++)
 		kfree(nf_ct_protos[i]);
 }
	/* L3/L4 protocol support for nf_conntrack. */

	/* (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) 2006-2012 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/slab.h>
	#include <linux/mutex.h>
	#include <linux/vmalloc.h>
	#include <linux/stddef.h>
	#include <linux/err.h>
	#include <linux/percpu.h>
	#include <linux/notifier.h>
	#include <linux/kernel.h>
	#include <linux/netdevice.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_core.h>

	static struct nf_conntrack_l4proto __rcu **nf_ct_protos[NFPROTO_NUMPROTO] __read_mostly;
	struct nf_conntrack_l3proto __rcu *nf_ct_l3protos[NFPROTO_NUMPROTO] __read_mostly;
	EXPORT_SYMBOL_GPL(nf_ct_l3protos);

	static DEFINE_MUTEX(nf_ct_proto_mutex);

	#ifdef CONFIG_SYSCTL
	static int
	nf_ct_register_sysctl(struct net *net,
	struct ctl_table_header **header,
	const char *path,
	struct ctl_table *table)
	{
	if (*header == NULL) {
	*header = register_net_sysctl(net, path, table);
	if (*header == NULL)
	return -ENOMEM;
	}

	return 0;
	}

	static void
	nf_ct_unregister_sysctl(struct ctl_table_header **header,
	struct ctl_table **table,
	unsigned int users)
	{
	if (users > 0)
	return;

	unregister_net_sysctl_table(*header);
	kfree(*table);
	*header = NULL;
	*table = NULL;
	}
	#endif

	const struct nf_conntrack_l4proto *
	__nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
	{
	if (unlikely(l3proto >= NFPROTO_NUMPROTO \|\| nf_ct_protos[l3proto] == NULL))
	return &nf_conntrack_l4proto_generic;

	return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
	}
	EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);

	/* this is guaranteed to always return a valid protocol helper, since
	* it falls back to generic_protocol */
	const struct nf_conntrack_l3proto *
	nf_ct_l3proto_find_get(u_int16_t l3proto)
	{
	struct nf_conntrack_l3proto *p;

	rcu_read_lock();
	p = __nf_ct_l3proto_find(l3proto);
	if (!try_module_get(p->me))
	p = &nf_conntrack_l3proto_generic;
	rcu_read_unlock();

	return p;
	}
	EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);

	int
	nf_ct_l3proto_try_module_get(unsigned short l3proto)
	{
	const struct nf_conntrack_l3proto *p;
	int ret;

	retry: p = nf_ct_l3proto_find_get(l3proto);
	if (p == &nf_conntrack_l3proto_generic) {
	ret = request_module("nf_conntrack-%d", l3proto);
	if (!ret)
	goto retry;

	return -EPROTOTYPE;
	}

	return 0;
	}
	EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);

	void nf_ct_l3proto_module_put(unsigned short l3proto)
	{
	struct nf_conntrack_l3proto *p;

	/* rcu_read_lock not necessary since the caller holds a reference, but
	* taken anyways to avoid lockdep warnings in __nf_ct_l3proto_find()
	*/
	rcu_read_lock();
	p = __nf_ct_l3proto_find(l3proto);
	module_put(p->me);
	rcu_read_unlock();
	}
	EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);

	int nf_ct_netns_get(struct net *net, u8 nfproto)
	{
	const struct nf_conntrack_l3proto *l3proto;
	int ret;

	might_sleep();

	ret = nf_ct_l3proto_try_module_get(nfproto);
	if (ret < 0)
	return ret;

	/* we already have a reference, can't fail */
	rcu_read_lock();
	l3proto = __nf_ct_l3proto_find(nfproto);
	rcu_read_unlock();

	if (!l3proto->net_ns_get)
	return 0;

	ret = l3proto->net_ns_get(net);
	if (ret < 0)
	nf_ct_l3proto_module_put(nfproto);

	return ret;
	}
	EXPORT_SYMBOL_GPL(nf_ct_netns_get);

	void nf_ct_netns_put(struct net *net, u8 nfproto)
	{
	const struct nf_conntrack_l3proto *l3proto;

	might_sleep();

	/* same as nf_conntrack_netns_get(), reference assumed */
	rcu_read_lock();
	l3proto = __nf_ct_l3proto_find(nfproto);
	rcu_read_unlock();

	if (WARN_ON(!l3proto))
	return;

	if (l3proto->net_ns_put)
	l3proto->net_ns_put(net);

	nf_ct_l3proto_module_put(nfproto);
	}
	EXPORT_SYMBOL_GPL(nf_ct_netns_put);

	const struct nf_conntrack_l4proto *
	nf_ct_l4proto_find_get(u_int16_t l3num, u_int8_t l4num)
	{
	const struct nf_conntrack_l4proto *p;

	rcu_read_lock();
	p = __nf_ct_l4proto_find(l3num, l4num);
	if (!try_module_get(p->me))
	p = &nf_conntrack_l4proto_generic;
	rcu_read_unlock();

	return p;
	}
	EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);

	void nf_ct_l4proto_put(const struct nf_conntrack_l4proto *p)
	{
	module_put(p->me);
	}
	EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);

	static int kill_l3proto(struct nf_conn i, void data)
	{
	return nf_ct_l3num(i) == ((const struct nf_conntrack_l3proto *)data)->l3proto;
	}

	static int kill_l4proto(struct nf_conn i, void data)
	{
	const struct nf_conntrack_l4proto *l4proto;
	l4proto = data;
	return nf_ct_protonum(i) == l4proto->l4proto &&
	nf_ct_l3num(i) == l4proto->l3proto;
	}

	int nf_ct_l3proto_register(const struct nf_conntrack_l3proto *proto)
	{
	int ret = 0;
	struct nf_conntrack_l3proto *old;

	if (proto->l3proto >= NFPROTO_NUMPROTO)
	return -EBUSY;
	#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
	if (proto->tuple_to_nlattr && proto->nla_size == 0)
	return -EINVAL;
	#endif
	mutex_lock(&nf_ct_proto_mutex);
	old = rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
	lockdep_is_held(&nf_ct_proto_mutex));
	if (old != &nf_conntrack_l3proto_generic) {
	ret = -EBUSY;
	goto out_unlock;
	}

	rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);

	out_unlock:
	mutex_unlock(&nf_ct_proto_mutex);
	return ret;

	}
	EXPORT_SYMBOL_GPL(nf_ct_l3proto_register);

	void nf_ct_l3proto_unregister(const struct nf_conntrack_l3proto *proto)
	{
	BUG_ON(proto->l3proto >= NFPROTO_NUMPROTO);

	mutex_lock(&nf_ct_proto_mutex);
	BUG_ON(rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
	lockdep_is_held(&nf_ct_proto_mutex)
	) != proto);
	rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
	&nf_conntrack_l3proto_generic);
	mutex_unlock(&nf_ct_proto_mutex);

	synchronize_rcu();
	/* Remove all contrack entries for this protocol */
	nf_ct_iterate_destroy(kill_l3proto, (void*)proto);
	}
	EXPORT_SYMBOL_GPL(nf_ct_l3proto_unregister);

	static struct nf_proto_net nf_ct_l4proto_net(struct net net,
	const struct nf_conntrack_l4proto *l4proto)
	{
	if (l4proto->get_net_proto) {
	/* statically built-in protocols use static per-net */
	return l4proto->get_net_proto(net);
	} else if (l4proto->net_id) {
	/* ... and loadable protocols use dynamic per-net */
	return net_generic(net, *l4proto->net_id);
	}
	return NULL;
	}

	static
	int nf_ct_l4proto_register_sysctl(struct net *net,
	struct nf_proto_net *pn,
	const struct nf_conntrack_l4proto *l4proto)
	{
	int err = 0;

	#ifdef CONFIG_SYSCTL
	if (pn->ctl_table != NULL) {
	err = nf_ct_register_sysctl(net,
	&pn->ctl_table_header,
	"net/netfilter",
	pn->ctl_table);
	if (err < 0) {
	if (!pn->users) {
	kfree(pn->ctl_table);
	pn->ctl_table = NULL;
	}
	}
	}
	#endif /* CONFIG_SYSCTL */
	return err;
	}

	static
	void nf_ct_l4proto_unregister_sysctl(struct net *net,
	struct nf_proto_net *pn,
	const struct nf_conntrack_l4proto *l4proto)
	{
	#ifdef CONFIG_SYSCTL
	if (pn->ctl_table_header != NULL)
	nf_ct_unregister_sysctl(&pn->ctl_table_header,
	&pn->ctl_table,
	pn->users);
	#endif /* CONFIG_SYSCTL */
	}

	/* FIXME: Allow NULL functions and sub in pointers to generic for
	them. --RR */
	int nf_ct_l4proto_register_one(struct nf_conntrack_l4proto *l4proto)
	{
	int ret = 0;

	if (l4proto->l3proto >= ARRAY_SIZE(nf_ct_protos))
	return -EBUSY;

	if ((l4proto->to_nlattr && !l4proto->nlattr_size) \|\|
	(l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
	return -EINVAL;

	mutex_lock(&nf_ct_proto_mutex);
	if (!nf_ct_protos[l4proto->l3proto]) {
	/* l3proto may be loaded latter. */
	struct nf_conntrack_l4proto __rcu **proto_array;
	int i;

	proto_array = kmalloc(MAX_NF_CT_PROTO *
	sizeof(struct nf_conntrack_l4proto *),
	GFP_KERNEL);
	if (proto_array == NULL) {
	ret = -ENOMEM;
	goto out_unlock;
	}

	for (i = 0; i < MAX_NF_CT_PROTO; i++)
	RCU_INIT_POINTER(proto_array[i],
	&nf_conntrack_l4proto_generic);

	/* Before making proto_array visible to lockless readers,
	* we must make sure its content is committed to memory.
	*/
	smp_wmb();

	nf_ct_protos[l4proto->l3proto] = proto_array;
	} else if (rcu_dereference_protected(
	nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
	lockdep_is_held(&nf_ct_proto_mutex)
	) != &nf_conntrack_l4proto_generic) {
	ret = -EBUSY;
	goto out_unlock;
	}

	l4proto->nla_size = 0;
	if (l4proto->nlattr_size)
	l4proto->nla_size += l4proto->nlattr_size();
	if (l4proto->nlattr_tuple_size)
	l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();

	rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
	l4proto);
	out_unlock:
	mutex_unlock(&nf_ct_proto_mutex);
	return ret;
	}
	EXPORT_SYMBOL_GPL(nf_ct_l4proto_register_one);

	int nf_ct_l4proto_pernet_register_one(struct net *net,
	const struct nf_conntrack_l4proto *l4proto)
	{
	int ret = 0;
	struct nf_proto_net *pn = NULL;

	if (l4proto->init_net) {
	ret = l4proto->init_net(net, l4proto->l3proto);
	if (ret < 0)
	goto out;
	}

	pn = nf_ct_l4proto_net(net, l4proto);
	if (pn == NULL)
	goto out;

	ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
	if (ret < 0)
	goto out;

	pn->users++;
	out:
	return ret;
	}
	EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register_one);

	static void __nf_ct_l4proto_unregister_one(const struct nf_conntrack_l4proto *l4proto)

	{
	BUG_ON(l4proto->l3proto >= ARRAY_SIZE(nf_ct_protos));

	BUG_ON(rcu_dereference_protected(
	nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
	lockdep_is_held(&nf_ct_proto_mutex)
	) != l4proto);
	rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
	&nf_conntrack_l4proto_generic);
	}

	void nf_ct_l4proto_unregister_one(const struct nf_conntrack_l4proto *l4proto)
	{
	mutex_lock(&nf_ct_proto_mutex);
	__nf_ct_l4proto_unregister_one(l4proto);
	mutex_unlock(&nf_ct_proto_mutex);

	synchronize_rcu();
	}
	EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister_one);

	void nf_ct_l4proto_pernet_unregister_one(struct net *net,
	const struct nf_conntrack_l4proto *l4proto)
	{
	struct nf_proto_net *pn = nf_ct_l4proto_net(net, l4proto);

	if (pn == NULL)
	return;

	pn->users--;
	nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
	}
	EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister_one);

	int nf_ct_l4proto_register(struct nf_conntrack_l4proto *l4proto[],
	unsigned int num_proto)
	{
	int ret = -EINVAL, ver;
	unsigned int i;

	for (i = 0; i < num_proto; i++) {
	ret = nf_ct_l4proto_register_one(l4proto[i]);
	if (ret < 0)
	break;
	}
	if (i != num_proto) {
	ver = l4proto[i]->l3proto == PF_INET6 ? 6 : 4;
	pr_err("nf_conntrack_ipv%d: can't register l4 %d proto.\n",
	ver, l4proto[i]->l4proto);
	nf_ct_l4proto_unregister(l4proto, i);
	}
	return ret;
	}
	EXPORT_SYMBOL_GPL(nf_ct_l4proto_register);

	int nf_ct_l4proto_pernet_register(struct net *net,
	struct nf_conntrack_l4proto *const l4proto[],
	unsigned int num_proto)
	{
	int ret = -EINVAL;
	unsigned int i;

	for (i = 0; i < num_proto; i++) {
	ret = nf_ct_l4proto_pernet_register_one(net, l4proto[i]);
	if (ret < 0)
	break;
	}
	if (i != num_proto) {
	pr_err("nf_conntrack_proto_%d %d: pernet registration failed\n",
	l4proto[i]->l4proto,
	l4proto[i]->l3proto == PF_INET6 ? 6 : 4);
	nf_ct_l4proto_pernet_unregister(net, l4proto, i);
	}
	return ret;
	}
	EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register);

	void nf_ct_l4proto_unregister(struct nf_conntrack_l4proto *l4proto[],
	unsigned int num_proto)
	{
	mutex_lock(&nf_ct_proto_mutex);
	while (num_proto-- != 0)
	__nf_ct_l4proto_unregister_one(l4proto[num_proto]);
	mutex_unlock(&nf_ct_proto_mutex);

	synchronize_net();
	/* Remove all contrack entries for this protocol */
	nf_ct_iterate_destroy(kill_l4proto, l4proto);
	}
	EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister);

	void nf_ct_l4proto_pernet_unregister(struct net *net,
	struct nf_conntrack_l4proto *const l4proto[],
	unsigned int num_proto)
	{
	while (num_proto-- != 0)
	nf_ct_l4proto_pernet_unregister_one(net, l4proto[num_proto]);
	}
	EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister);

	int nf_conntrack_proto_pernet_init(struct net *net)
	{
	int err;
	struct nf_proto_net *pn = nf_ct_l4proto_net(net,
	&nf_conntrack_l4proto_generic);

	err = nf_conntrack_l4proto_generic.init_net(net,
	nf_conntrack_l4proto_generic.l3proto);
	if (err < 0)
	return err;
	err = nf_ct_l4proto_register_sysctl(net,
	pn,
	&nf_conntrack_l4proto_generic);
	if (err < 0)
	return err;

	pn->users++;
	return 0;
	}

	void nf_conntrack_proto_pernet_fini(struct net *net)
	{
	struct nf_proto_net *pn = nf_ct_l4proto_net(net,
	&nf_conntrack_l4proto_generic);

	pn->users--;
	nf_ct_l4proto_unregister_sysctl(net,
	pn,
	&nf_conntrack_l4proto_generic);
	}

	int nf_conntrack_proto_init(void)
	{
	unsigned int i;
	for (i = 0; i < NFPROTO_NUMPROTO; i++)
	rcu_assign_pointer(nf_ct_l3protos[i],
	&nf_conntrack_l3proto_generic);
	return 0;
	}

	void nf_conntrack_proto_fini(void)
	{
	unsigned int i;
	/* free l3proto protocol tables */
	for (i = 0; i < ARRAY_SIZE(nf_ct_protos); i++)
	kfree(nf_ct_protos[i]);
	}