[net-next-2.6.git] / net / ipv4 / netfilter / ipt_MASQUERADE.c

/* Masquerade.  Simple mapping which alters range to a local IP address
   (depending on route). */

/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
 *
 * 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/config.h>
#include <linux/types.h>
#include <linux/inetdevice.h>
#include <linux/ip.h>
#include <linux/timer.h>
#include <linux/module.h>
#include <linux/netfilter.h>
#include <net/protocol.h>
#include <net/ip.h>
#include <net/checksum.h>
#include <net/route.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv4/ip_nat_rule.h>
#include <linux/netfilter_ipv4/ip_tables.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
MODULE_DESCRIPTION("iptables MASQUERADE target module");

#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif

/* Lock protects masq region inside conntrack */
static DEFINE_RWLOCK(masq_lock);

/* FIXME: Multiple targets. --RR */
static int
masquerade_check(const char *tablename,
		 const struct ipt_entry *e,
		 void *targinfo,
		 unsigned int targinfosize,
		 unsigned int hook_mask)
{
	const struct ip_nat_multi_range_compat *mr = targinfo;

	if (strcmp(tablename, "nat") != 0) {
		DEBUGP("masquerade_check: bad table `%s'.\n", tablename);
		return 0;
	}
	if (targinfosize != IPT_ALIGN(sizeof(*mr))) {
		DEBUGP("masquerade_check: size %u != %u.\n",
		       targinfosize, sizeof(*mr));
		return 0;
	}
	if (hook_mask & ~(1 << NF_IP_POST_ROUTING)) {
		DEBUGP("masquerade_check: bad hooks %x.\n", hook_mask);
		return 0;
	}
	if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) {
		DEBUGP("masquerade_check: bad MAP_IPS.\n");
		return 0;
	}
	if (mr->rangesize != 1) {
		DEBUGP("masquerade_check: bad rangesize %u.\n", mr->rangesize);
		return 0;
	}
	return 1;
}

static unsigned int
masquerade_target(struct sk_buff **pskb,
		  const struct net_device *in,
		  const struct net_device *out,
		  unsigned int hooknum,
		  const void *targinfo,
		  void *userinfo)
{
	struct ip_conntrack *ct;
	enum ip_conntrack_info ctinfo;
	const struct ip_nat_multi_range_compat *mr;
	struct ip_nat_range newrange;
	struct rtable *rt;
	u_int32_t newsrc;

	IP_NF_ASSERT(hooknum == NF_IP_POST_ROUTING);

	ct = ip_conntrack_get(*pskb, &ctinfo);
	IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED
	                    || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));

	/* Source address is 0.0.0.0 - locally generated packet that is
	 * probably not supposed to be masqueraded.
	 */
	if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip == 0)
		return NF_ACCEPT;

	mr = targinfo;
	rt = (struct rtable *)(*pskb)->dst;
	newsrc = inet_select_addr(out, rt->rt_gateway, RT_SCOPE_UNIVERSE);
	if (!newsrc) {
		printk("MASQUERADE: %s ate my IP address\n", out->name);
		return NF_DROP;
	}

	write_lock_bh(&masq_lock);
	ct->nat.masq_index = out->ifindex;
	write_unlock_bh(&masq_lock);

	/* Transfer from original range. */
	newrange = ((struct ip_nat_range)
		{ mr->range[0].flags | IP_NAT_RANGE_MAP_IPS,
		  newsrc, newsrc,
		  mr->range[0].min, mr->range[0].max });

	/* Hand modified range to generic setup. */
	return ip_nat_setup_info(ct, &newrange, hooknum);
}

static inline int
device_cmp(struct ip_conntrack *i, void *ifindex)
{
	int ret;

	read_lock_bh(&masq_lock);
	ret = (i->nat.masq_index == (int)(long)ifindex);
	read_unlock_bh(&masq_lock);

	return ret;
}

static int masq_device_event(struct notifier_block *this,
			     unsigned long event,
			     void *ptr)
{
	struct net_device *dev = ptr;

	if (event == NETDEV_DOWN) {
		/* Device was downed.  Search entire table for
		   conntracks which were associated with that device,
		   and forget them. */
		IP_NF_ASSERT(dev->ifindex != 0);

		ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
	}

	return NOTIFY_DONE;
}

static int masq_inet_event(struct notifier_block *this,
			   unsigned long event,
			   void *ptr)
{
	struct net_device *dev = ((struct in_ifaddr *)ptr)->ifa_dev->dev;

	if (event == NETDEV_DOWN) {
		/* IP address was deleted.  Search entire table for
		   conntracks which were associated with that device,
		   and forget them. */
		IP_NF_ASSERT(dev->ifindex != 0);

		ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
	}

	return NOTIFY_DONE;
}

static struct notifier_block masq_dev_notifier = {
	.notifier_call	= masq_device_event,
};

static struct notifier_block masq_inet_notifier = {
	.notifier_call	= masq_inet_event,
};

static struct ipt_target masquerade = {
	.name		= "MASQUERADE",
	.target		= masquerade_target,
	.checkentry	= masquerade_check,
	.me		= THIS_MODULE,
};

static int __init init(void)
{
	int ret;

	ret = ipt_register_target(&masquerade);

	if (ret == 0) {
		/* Register for device down reports */
		register_netdevice_notifier(&masq_dev_notifier);
		/* Register IP address change reports */
		register_inetaddr_notifier(&masq_inet_notifier);
	}

	return ret;
}

static void __exit fini(void)
{
	ipt_unregister_target(&masquerade);
	unregister_netdevice_notifier(&masq_dev_notifier);
	unregister_inetaddr_notifier(&masq_inet_notifier);	
}

module_init(init);
module_exit(fini);
Commit	Line	Data
1da177e4 LT	1	/* Masquerade. Simple mapping which alters range to a local IP address
	2	(depending on route). */
	3
	4	/* (C) 1999-2001 Paul `Rusty' Russell
	5	* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 as
	9	* published by the Free Software Foundation.
	10	*/
	11
	12	#include <linux/config.h>
	13	#include <linux/types.h>
14c85021	14	#include <linux/inetdevice.h>
1da177e4 LT	15	#include <linux/ip.h>
	16	#include <linux/timer.h>
	17	#include <linux/module.h>
	18	#include <linux/netfilter.h>
	19	#include <net/protocol.h>
	20	#include <net/ip.h>
	21	#include <net/checksum.h>
14c85021	22	#include <net/route.h>
1da177e4 LT	23	#include <linux/netfilter_ipv4.h>
	24	#include <linux/netfilter_ipv4/ip_nat_rule.h>
	25	#include <linux/netfilter_ipv4/ip_tables.h>
	26
	27	MODULE_LICENSE("GPL");
	28	MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
	29	MODULE_DESCRIPTION("iptables MASQUERADE target module");
	30
	31	#if 0
	32	#define DEBUGP printk
	33	#else
	34	#define DEBUGP(format, args...)
	35	#endif
	36
	37	/* Lock protects masq region inside conntrack */
e45b1be8	38	static DEFINE_RWLOCK(masq_lock);
1da177e4 LT	39
	40	/* FIXME: Multiple targets. --RR */
	41	static int
	42	masquerade_check(const char *tablename,
	43	const struct ipt_entry *e,
	44	void *targinfo,
	45	unsigned int targinfosize,
	46	unsigned int hook_mask)
	47	{
	48	const struct ip_nat_multi_range_compat *mr = targinfo;
	49
	50	if (strcmp(tablename, "nat") != 0) {
	51	DEBUGP("masquerade_check: bad table `%s'.\n", tablename);
	52	return 0;
	53	}
	54	if (targinfosize != IPT_ALIGN(sizeof(*mr))) {
	55	DEBUGP("masquerade_check: size %u != %u.\n",
	56	targinfosize, sizeof(*mr));
	57	return 0;
	58	}
	59	if (hook_mask & ~(1 << NF_IP_POST_ROUTING)) {
	60	DEBUGP("masquerade_check: bad hooks %x.\n", hook_mask);
	61	return 0;
	62	}
	63	if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) {
	64	DEBUGP("masquerade_check: bad MAP_IPS.\n");
	65	return 0;
	66	}
	67	if (mr->rangesize != 1) {
	68	DEBUGP("masquerade_check: bad rangesize %u.\n", mr->rangesize);
	69	return 0;
	70	}
	71	return 1;
	72	}
	73
	74	static unsigned int
	75	masquerade_target(struct sk_buff **pskb,
	76	const struct net_device *in,
	77	const struct net_device *out,
	78	unsigned int hooknum,
	79	const void *targinfo,
	80	void *userinfo)
	81	{
	82	struct ip_conntrack *ct;
	83	enum ip_conntrack_info ctinfo;
	84	const struct ip_nat_multi_range_compat *mr;
	85	struct ip_nat_range newrange;
	86	struct rtable *rt;
	87	u_int32_t newsrc;
	88
	89	IP_NF_ASSERT(hooknum == NF_IP_POST_ROUTING);
	90
1da177e4 LT	91	ct = ip_conntrack_get(*pskb, &ctinfo);
	92	IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW \|\| ctinfo == IP_CT_RELATED
	93	\|\| ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
	94
adcb5ad1 PM	95	/* Source address is 0.0.0.0 - locally generated packet that is
	96	* probably not supposed to be masqueraded.
	97	*/
	98	if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip == 0)
	99	return NF_ACCEPT;
	100
1da177e4 LT	101	mr = targinfo;
	102	rt = (struct rtable )(pskb)->dst;
	103	newsrc = inet_select_addr(out, rt->rt_gateway, RT_SCOPE_UNIVERSE);
	104	if (!newsrc) {
	105	printk("MASQUERADE: %s ate my IP address\n", out->name);
	106	return NF_DROP;
	107	}
	108
e45b1be8	109	write_lock_bh(&masq_lock);
1da177e4	110	ct->nat.masq_index = out->ifindex;
e45b1be8	111	write_unlock_bh(&masq_lock);
1da177e4 LT	112
	113	/* Transfer from original range. */
	114	newrange = ((struct ip_nat_range)
	115	{ mr->range[0].flags \| IP_NAT_RANGE_MAP_IPS,
	116	newsrc, newsrc,
	117	mr->range[0].min, mr->range[0].max });
	118
	119	/* Hand modified range to generic setup. */
	120	return ip_nat_setup_info(ct, &newrange, hooknum);
	121	}
	122
	123	static inline int
	124	device_cmp(struct ip_conntrack i, void ifindex)
	125	{
	126	int ret;
	127
e45b1be8	128	read_lock_bh(&masq_lock);
1da177e4	129	ret = (i->nat.masq_index == (int)(long)ifindex);
e45b1be8	130	read_unlock_bh(&masq_lock);
1da177e4 LT	131
	132	return ret;
	133	}
	134
	135	static int masq_device_event(struct notifier_block *this,
	136	unsigned long event,
	137	void *ptr)
	138	{
	139	struct net_device *dev = ptr;
	140
	141	if (event == NETDEV_DOWN) {
	142	/* Device was downed. Search entire table for
	143	conntracks which were associated with that device,
	144	and forget them. */
	145	IP_NF_ASSERT(dev->ifindex != 0);
	146
	147	ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
	148	}
	149
	150	return NOTIFY_DONE;
	151	}
	152
	153	static int masq_inet_event(struct notifier_block *this,
	154	unsigned long event,
	155	void *ptr)
	156	{
	157	struct net_device dev = ((struct in_ifaddr )ptr)->ifa_dev->dev;
	158
	159	if (event == NETDEV_DOWN) {
	160	/* IP address was deleted. Search entire table for
	161	conntracks which were associated with that device,
	162	and forget them. */
	163	IP_NF_ASSERT(dev->ifindex != 0);
	164
	165	ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
	166	}
	167
	168	return NOTIFY_DONE;
	169	}
	170
	171	static struct notifier_block masq_dev_notifier = {
	172	.notifier_call = masq_device_event,
	173	};
	174
	175	static struct notifier_block masq_inet_notifier = {
	176	.notifier_call = masq_inet_event,
	177	};
	178
	179	static struct ipt_target masquerade = {
	180	.name = "MASQUERADE",
	181	.target = masquerade_target,
	182	.checkentry = masquerade_check,
	183	.me = THIS_MODULE,
	184	};
	185
	186	static int __init init(void)
	187	{
	188	int ret;
	189
	190	ret = ipt_register_target(&masquerade);
	191
	192	if (ret == 0) {
	193	/* Register for device down reports */
	194	register_netdevice_notifier(&masq_dev_notifier);
195	/* Register IP address change reports */
196	register_inetaddr_notifier(&masq_inet_notifier);
197	}
198
199	return ret;
200	}
201
202	static void __exit fini(void)
203	{
204	ipt_unregister_target(&masquerade);
205	unregister_netdevice_notifier(&masq_dev_notifier);
206	unregister_inetaddr_notifier(&masq_inet_notifier);
207	}
208
209	module_init(init);
210	module_exit(fini);