net/netfilter/nfnetlink.c - linux - Git at Google

 /* Netfilter messages via netlink socket. Allows for user space
  * protocol helpers and general trouble making from userspace.
  *
  * (C) 2001 by Jay Schulist <jschlst@samba.org>,
  * (C) 2002-2005 by Harald Welte <laforge@gnumonks.org>
  * (C) 2005,2007 by Pablo Neira Ayuso <pablo@netfilter.org>
  *
  * Initial netfilter messages via netlink development funded and
  * generally made possible by Network Robots, Inc. (www.networkrobots.com)
  *
  * Further development of this code funded by Astaro AG (http://www.astaro.com)
  *
  * This software may be used and distributed according to the terms
  * of the GNU General Public License, incorporated herein by reference.
  */

 #include <linux/module.h>
 #include <linux/types.h>
 #include <linux/socket.h>
 #include <linux/kernel.h>
 #include <linux/string.h>
 #include <linux/sockios.h>
 #include <linux/net.h>
 #include <linux/skbuff.h>
 #include <asm/uaccess.h>
 #include <net/sock.h>
 #include <net/netlink.h>
 #include <linux/init.h>

 #include <linux/netlink.h>
 #include <linux/netfilter/nfnetlink.h>

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);

 static char __initdata nfversion[] = "0.30";

 static const struct nfnetlink_subsystem __rcu *subsys_table[NFNL_SUBSYS_COUNT];
 static DEFINE_MUTEX(nfnl_mutex);

 static const int nfnl_group2type[NFNLGRP_MAX+1] = {
 	[NFNLGRP_CONNTRACK_NEW]		= NFNL_SUBSYS_CTNETLINK,
 	[NFNLGRP_CONNTRACK_UPDATE]	= NFNL_SUBSYS_CTNETLINK,
 	[NFNLGRP_CONNTRACK_DESTROY]	= NFNL_SUBSYS_CTNETLINK,
 	[NFNLGRP_CONNTRACK_EXP_NEW]	= NFNL_SUBSYS_CTNETLINK_EXP,
 	[NFNLGRP_CONNTRACK_EXP_UPDATE]	= NFNL_SUBSYS_CTNETLINK_EXP,
 	[NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP,
 };

 void nfnl_lock(void)
 {
 	mutex_lock(&nfnl_mutex);
 }
 EXPORT_SYMBOL_GPL(nfnl_lock);

 void nfnl_unlock(void)
 {
 	mutex_unlock(&nfnl_mutex);
 }
 EXPORT_SYMBOL_GPL(nfnl_unlock);

 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
 {
 	nfnl_lock();
 	if (subsys_table[n->subsys_id]) {
 		nfnl_unlock();
 		return -EBUSY;
 	}
 	rcu_assign_pointer(subsys_table[n->subsys_id], n);
 	nfnl_unlock();

 	return 0;
 }
 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);

 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
 {
 	nfnl_lock();
 	subsys_table[n->subsys_id] = NULL;
 	nfnl_unlock();
 	synchronize_rcu();
 	return 0;
 }
 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);

 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type)
 {
 	u_int8_t subsys_id = NFNL_SUBSYS_ID(type);

 	if (subsys_id >= NFNL_SUBSYS_COUNT)
 		return NULL;

 	return rcu_dereference(subsys_table[subsys_id]);
 }

 static inline const struct nfnl_callback *
 nfnetlink_find_client(u_int16_t type, const struct nfnetlink_subsystem *ss)
 {
 	u_int8_t cb_id = NFNL_MSG_TYPE(type);

 	if (cb_id >= ss->cb_count)
 		return NULL;

 	return &ss->cb[cb_id];
 }

 int nfnetlink_has_listeners(struct net *net, unsigned int group)
 {
 	return netlink_has_listeners(net->nfnl, group);
 }
 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);

 int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 pid,
 		   unsigned int group, int echo, gfp_t flags)
 {
 	return nlmsg_notify(net->nfnl, skb, pid, group, echo, flags);
 }
 EXPORT_SYMBOL_GPL(nfnetlink_send);

 int nfnetlink_set_err(struct net *net, u32 pid, u32 group, int error)
 {
 	return netlink_set_err(net->nfnl, pid, group, error);
 }
 EXPORT_SYMBOL_GPL(nfnetlink_set_err);

 int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u_int32_t pid, int flags)
 {
 	return netlink_unicast(net->nfnl, skb, pid, flags);
 }
 EXPORT_SYMBOL_GPL(nfnetlink_unicast);

 /* Process one complete nfnetlink message. */
 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 {
 	struct net *net = sock_net(skb->sk);
 	const struct nfnl_callback *nc;
 	const struct nfnetlink_subsystem *ss;
 	int type, err;

 	if (!capable(CAP_NET_ADMIN))
 		return -EPERM;

 	/* All the messages must at least contain nfgenmsg */
 	if (nlh->nlmsg_len < NLMSG_LENGTH(sizeof(struct nfgenmsg)))
 		return 0;

 	type = nlh->nlmsg_type;
 replay:
 	rcu_read_lock();
 	ss = nfnetlink_get_subsys(type);
 	if (!ss) {
 #ifdef CONFIG_MODULES
 		rcu_read_unlock();
 		request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
 		rcu_read_lock();
 		ss = nfnetlink_get_subsys(type);
 		if (!ss)
 #endif
 		{
 			rcu_read_unlock();
 			return -EINVAL;
 		}
 	}

 	nc = nfnetlink_find_client(type, ss);
 	if (!nc) {
 		rcu_read_unlock();
 		return -EINVAL;
 	}

 	{
 		int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
 		u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
 		struct nlattr *cda[ss->cb[cb_id].attr_count + 1];
 		struct nlattr *attr = (void *)nlh + min_len;
 		int attrlen = nlh->nlmsg_len - min_len;

 		err = nla_parse(cda, ss->cb[cb_id].attr_count,
 				attr, attrlen, ss->cb[cb_id].policy);
 		if (err < 0) {
 			rcu_read_unlock();
 			return err;
 		}

 		if (nc->call_rcu) {
 			err = nc->call_rcu(net->nfnl, skb, nlh,
 					   (const struct nlattr **)cda);
 			rcu_read_unlock();
 		} else {
 			rcu_read_unlock();
 			nfnl_lock();
 			if (rcu_dereference_protected(
 					subsys_table[NFNL_SUBSYS_ID(type)],
 					lockdep_is_held(&nfnl_mutex)) != ss ||
 			    nfnetlink_find_client(type, ss) != nc)
 				err = -EAGAIN;
 			else if (nc->call)
 				err = nc->call(net->nfnl, skb, nlh,
 						   (const struct nlattr **)cda);
 			else
 				err = -EINVAL;
 			nfnl_unlock();
 		}
 		if (err == -EAGAIN)
 			goto replay;
 		return err;
 	}
 }

 static void nfnetlink_rcv(struct sk_buff *skb)
 {
 	netlink_rcv_skb(skb, &nfnetlink_rcv_msg);
 }

 #ifdef CONFIG_MODULES
 static void nfnetlink_bind(int group)
 {
 	const struct nfnetlink_subsystem *ss;
 	int type = nfnl_group2type[group];

 	rcu_read_lock();
 	ss = nfnetlink_get_subsys(type);
 	if (!ss) {
 		rcu_read_unlock();
 		request_module("nfnetlink-subsys-%d", type);
 		return;
 	}
 	rcu_read_unlock();
 }
 #endif

 static int __net_init nfnetlink_net_init(struct net *net)
 {
 	struct sock *nfnl;
 	struct netlink_kernel_cfg cfg = {
 		.groups	= NFNLGRP_MAX,
 		.input	= nfnetlink_rcv,
 #ifdef CONFIG_MODULES
 		.bind	= nfnetlink_bind,
 #endif
 	};

 	nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, THIS_MODULE, &cfg);
 	if (!nfnl)
 		return -ENOMEM;
 	net->nfnl_stash = nfnl;
 	rcu_assign_pointer(net->nfnl, nfnl);
 	return 0;
 }

 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list)
 {
 	struct net *net;

 	list_for_each_entry(net, net_exit_list, exit_list)
 		RCU_INIT_POINTER(net->nfnl, NULL);
 	synchronize_net();
 	list_for_each_entry(net, net_exit_list, exit_list)
 		netlink_kernel_release(net->nfnl_stash);
 }

 static struct pernet_operations nfnetlink_net_ops = {
 	.init		= nfnetlink_net_init,
 	.exit_batch	= nfnetlink_net_exit_batch,
 };

 static int __init nfnetlink_init(void)
 {
 	pr_info("Netfilter messages via NETLINK v%s.\n", nfversion);
 	return register_pernet_subsys(&nfnetlink_net_ops);
 }

 static void __exit nfnetlink_exit(void)
 {
 	pr_info("Removing netfilter NETLINK layer.\n");
 	unregister_pernet_subsys(&nfnetlink_net_ops);
 }
 module_init(nfnetlink_init);
 module_exit(nfnetlink_exit);
	/* Netfilter messages via netlink socket. Allows for user space
	* protocol helpers and general trouble making from userspace.
	*
	* (C) 2001 by Jay Schulist <jschlst@samba.org>,
	* (C) 2002-2005 by Harald Welte <laforge@gnumonks.org>
	* (C) 2005,2007 by Pablo Neira Ayuso <pablo@netfilter.org>
	*
	* Initial netfilter messages via netlink development funded and
	* generally made possible by Network Robots, Inc. (www.networkrobots.com)
	*
	* Further development of this code funded by Astaro AG (http://www.astaro.com)
	*
	* This software may be used and distributed according to the terms
	* of the GNU General Public License, incorporated herein by reference.
	*/

	#include <linux/module.h>
	#include <linux/types.h>
	#include <linux/socket.h>
	#include <linux/kernel.h>
	#include <linux/string.h>
	#include <linux/sockios.h>
	#include <linux/net.h>
	#include <linux/skbuff.h>
	#include <asm/uaccess.h>
	#include <net/sock.h>
	#include <net/netlink.h>
	#include <linux/init.h>

	#include <linux/netlink.h>
	#include <linux/netfilter/nfnetlink.h>

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
	MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);

	static char __initdata nfversion[] = "0.30";

	static const struct nfnetlink_subsystem __rcu *subsys_table[NFNL_SUBSYS_COUNT];
	static DEFINE_MUTEX(nfnl_mutex);

	static const int nfnl_group2type[NFNLGRP_MAX+1] = {
	[NFNLGRP_CONNTRACK_NEW] = NFNL_SUBSYS_CTNETLINK,
	[NFNLGRP_CONNTRACK_UPDATE] = NFNL_SUBSYS_CTNETLINK,
	[NFNLGRP_CONNTRACK_DESTROY] = NFNL_SUBSYS_CTNETLINK,
	[NFNLGRP_CONNTRACK_EXP_NEW] = NFNL_SUBSYS_CTNETLINK_EXP,
	[NFNLGRP_CONNTRACK_EXP_UPDATE] = NFNL_SUBSYS_CTNETLINK_EXP,
	[NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP,
	};

	void nfnl_lock(void)
	{
	mutex_lock(&nfnl_mutex);
	}
	EXPORT_SYMBOL_GPL(nfnl_lock);

	void nfnl_unlock(void)
	{
	mutex_unlock(&nfnl_mutex);
	}
	EXPORT_SYMBOL_GPL(nfnl_unlock);

	int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
	{
	nfnl_lock();
	if (subsys_table[n->subsys_id]) {
	nfnl_unlock();
	return -EBUSY;
	}
	rcu_assign_pointer(subsys_table[n->subsys_id], n);
	nfnl_unlock();

	return 0;
	}
	EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);

	int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
	{
	nfnl_lock();
	subsys_table[n->subsys_id] = NULL;
	nfnl_unlock();
	synchronize_rcu();
	return 0;
	}
	EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);

	static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type)
	{
	u_int8_t subsys_id = NFNL_SUBSYS_ID(type);

	if (subsys_id >= NFNL_SUBSYS_COUNT)
	return NULL;

	return rcu_dereference(subsys_table[subsys_id]);
	}

	static inline const struct nfnl_callback *
	nfnetlink_find_client(u_int16_t type, const struct nfnetlink_subsystem *ss)
	{
	u_int8_t cb_id = NFNL_MSG_TYPE(type);

	if (cb_id >= ss->cb_count)
	return NULL;

	return &ss->cb[cb_id];
	}

	int nfnetlink_has_listeners(struct net *net, unsigned int group)
	{
	return netlink_has_listeners(net->nfnl, group);
	}
	EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);

	int nfnetlink_send(struct sk_buff skb, struct net net, u32 pid,
	unsigned int group, int echo, gfp_t flags)
	{
	return nlmsg_notify(net->nfnl, skb, pid, group, echo, flags);
	}
	EXPORT_SYMBOL_GPL(nfnetlink_send);

	int nfnetlink_set_err(struct net *net, u32 pid, u32 group, int error)
	{
	return netlink_set_err(net->nfnl, pid, group, error);
	}
	EXPORT_SYMBOL_GPL(nfnetlink_set_err);

	int nfnetlink_unicast(struct sk_buff skb, struct net net, u_int32_t pid, int flags)
	{
	return netlink_unicast(net->nfnl, skb, pid, flags);
	}
	EXPORT_SYMBOL_GPL(nfnetlink_unicast);

	/* Process one complete nfnetlink message. */
	static int nfnetlink_rcv_msg(struct sk_buff skb, struct nlmsghdr nlh)
	{
	struct net *net = sock_net(skb->sk);
	const struct nfnl_callback *nc;
	const struct nfnetlink_subsystem *ss;
	int type, err;

	if (!capable(CAP_NET_ADMIN))
	return -EPERM;

	/* All the messages must at least contain nfgenmsg */
	if (nlh->nlmsg_len < NLMSG_LENGTH(sizeof(struct nfgenmsg)))
	return 0;

	type = nlh->nlmsg_type;
	replay:
	rcu_read_lock();
	ss = nfnetlink_get_subsys(type);
	if (!ss) {
	#ifdef CONFIG_MODULES
	rcu_read_unlock();
	request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
	rcu_read_lock();
	ss = nfnetlink_get_subsys(type);
	if (!ss)
	#endif
	{
	rcu_read_unlock();
	return -EINVAL;
	}
	}

	nc = nfnetlink_find_client(type, ss);
	if (!nc) {
	rcu_read_unlock();
	return -EINVAL;
	}

	{
	int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
	u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
	struct nlattr *cda[ss->cb[cb_id].attr_count + 1];
	struct nlattr attr = (void )nlh + min_len;
	int attrlen = nlh->nlmsg_len - min_len;

	err = nla_parse(cda, ss->cb[cb_id].attr_count,
	attr, attrlen, ss->cb[cb_id].policy);
	if (err < 0) {
	rcu_read_unlock();
	return err;
	}

	if (nc->call_rcu) {
	err = nc->call_rcu(net->nfnl, skb, nlh,
	(const struct nlattr **)cda);
	rcu_read_unlock();
	} else {
	rcu_read_unlock();
	nfnl_lock();
	if (rcu_dereference_protected(
	subsys_table[NFNL_SUBSYS_ID(type)],
	lockdep_is_held(&nfnl_mutex)) != ss \|\|
	nfnetlink_find_client(type, ss) != nc)
	err = -EAGAIN;
	else if (nc->call)
	err = nc->call(net->nfnl, skb, nlh,
	(const struct nlattr **)cda);
	else
	err = -EINVAL;
	nfnl_unlock();
	}
	if (err == -EAGAIN)
	goto replay;
	return err;
	}
	}

	static void nfnetlink_rcv(struct sk_buff *skb)
	{
	netlink_rcv_skb(skb, &nfnetlink_rcv_msg);
	}

	#ifdef CONFIG_MODULES
	static void nfnetlink_bind(int group)
	{
	const struct nfnetlink_subsystem *ss;
	int type = nfnl_group2type[group];

	rcu_read_lock();
	ss = nfnetlink_get_subsys(type);
	if (!ss) {
	rcu_read_unlock();
	request_module("nfnetlink-subsys-%d", type);
	return;
	}
	rcu_read_unlock();
	}
	#endif

	static int __net_init nfnetlink_net_init(struct net *net)
	{
	struct sock *nfnl;
	struct netlink_kernel_cfg cfg = {
	.groups = NFNLGRP_MAX,
	.input = nfnetlink_rcv,
	#ifdef CONFIG_MODULES
	.bind = nfnetlink_bind,
	#endif
	};

	nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, THIS_MODULE, &cfg);
	if (!nfnl)
	return -ENOMEM;
	net->nfnl_stash = nfnl;
	rcu_assign_pointer(net->nfnl, nfnl);
	return 0;
	}

	static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list)
	{
	struct net *net;

	list_for_each_entry(net, net_exit_list, exit_list)
	RCU_INIT_POINTER(net->nfnl, NULL);
	synchronize_net();
	list_for_each_entry(net, net_exit_list, exit_list)
	netlink_kernel_release(net->nfnl_stash);
	}

	static struct pernet_operations nfnetlink_net_ops = {
	.init = nfnetlink_net_init,
	.exit_batch = nfnetlink_net_exit_batch,
	};

	static int __init nfnetlink_init(void)
	{
	pr_info("Netfilter messages via NETLINK v%s.\n", nfversion);
	return register_pernet_subsys(&nfnetlink_net_ops);
	}

	static void __exit nfnetlink_exit(void)
	{
	pr_info("Removing netfilter NETLINK layer.\n");
	unregister_pernet_subsys(&nfnetlink_net_ops);
	}
	module_init(nfnetlink_init);
	module_exit(nfnetlink_exit);