[deliverable/linux.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/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 void *e,
		 const struct xt_target *target,
		 void *targinfo,
		 unsigned int hook_mask)
{
	const struct ip_nat_multi_range_compat *mr = targinfo;

	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 struct xt_target *target,
		  const void *targinfo)
{
	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,
	.targetsize	= sizeof(struct ip_nat_multi_range_compat),
	.table		= "nat",
	.hooks		= 1 << NF_IP_POST_ROUTING,
	.checkentry	= masquerade_check,
	.me		= THIS_MODULE,
};

static int __init ipt_masquerade_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 ipt_masquerade_fini(void)
{
	ipt_unregister_target(&masquerade);
	unregister_netdevice_notifier(&masq_dev_notifier);
	unregister_inetaddr_notifier(&masq_inet_notifier);	
}

module_init(ipt_masquerade_init);
module_exit(ipt_masquerade_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
1da177e4	12	#include <linux/types.h>
14c85021	13	#include <linux/inetdevice.h>
1da177e4 LT	14	#include <linux/ip.h>
	15	#include <linux/timer.h>
	16	#include <linux/module.h>
	17	#include <linux/netfilter.h>
	18	#include <net/protocol.h>
	19	#include <net/ip.h>
	20	#include <net/checksum.h>
14c85021	21	#include <net/route.h>
1da177e4 LT	22	#include <linux/netfilter_ipv4.h>
	23	#include <linux/netfilter_ipv4/ip_nat_rule.h>
	24	#include <linux/netfilter_ipv4/ip_tables.h>
	25
	26	MODULE_LICENSE("GPL");
	27	MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
	28	MODULE_DESCRIPTION("iptables MASQUERADE target module");
	29
	30	#if 0
	31	#define DEBUGP printk
	32	#else
	33	#define DEBUGP(format, args...)
	34	#endif
	35
	36	/* Lock protects masq region inside conntrack */
e45b1be8	37	static DEFINE_RWLOCK(masq_lock);
1da177e4 LT	38
	39	/* FIXME: Multiple targets. --RR */
	40	static int
	41	masquerade_check(const char *tablename,
2e4e6a17	42	const void *e,
c4986734	43	const struct xt_target *target,
1da177e4	44	void *targinfo,
1da177e4 LT	45	unsigned int hook_mask)
	46	{
	47	const struct ip_nat_multi_range_compat *mr = targinfo;
	48
1da177e4 LT	49	if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) {
	50	DEBUGP("masquerade_check: bad MAP_IPS.\n");
	51	return 0;
	52	}
	53	if (mr->rangesize != 1) {
	54	DEBUGP("masquerade_check: bad rangesize %u.\n", mr->rangesize);
	55	return 0;
	56	}
	57	return 1;
	58	}
	59
	60	static unsigned int
	61	masquerade_target(struct sk_buff **pskb,
	62	const struct net_device *in,
	63	const struct net_device *out,
	64	unsigned int hooknum,
c4986734	65	const struct xt_target *target,
fe1cb108	66	const void *targinfo)
1da177e4 LT	67	{
	68	struct ip_conntrack *ct;
	69	enum ip_conntrack_info ctinfo;
	70	const struct ip_nat_multi_range_compat *mr;
	71	struct ip_nat_range newrange;
	72	struct rtable *rt;
	73	u_int32_t newsrc;
	74
	75	IP_NF_ASSERT(hooknum == NF_IP_POST_ROUTING);
	76
1da177e4 LT	77	ct = ip_conntrack_get(*pskb, &ctinfo);
	78	IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW \|\| ctinfo == IP_CT_RELATED
	79	\|\| ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
	80
adcb5ad1 PM	81	/* Source address is 0.0.0.0 - locally generated packet that is
	82	* probably not supposed to be masqueraded.
	83	*/
	84	if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip == 0)
	85	return NF_ACCEPT;
	86
1da177e4 LT	87	mr = targinfo;
	88	rt = (struct rtable )(pskb)->dst;
	89	newsrc = inet_select_addr(out, rt->rt_gateway, RT_SCOPE_UNIVERSE);
	90	if (!newsrc) {
	91	printk("MASQUERADE: %s ate my IP address\n", out->name);
	92	return NF_DROP;
	93	}
	94
e45b1be8	95	write_lock_bh(&masq_lock);
1da177e4	96	ct->nat.masq_index = out->ifindex;
e45b1be8	97	write_unlock_bh(&masq_lock);
1da177e4 LT	98
	99	/* Transfer from original range. */
	100	newrange = ((struct ip_nat_range)
	101	{ mr->range[0].flags \| IP_NAT_RANGE_MAP_IPS,
	102	newsrc, newsrc,
	103	mr->range[0].min, mr->range[0].max });
	104
	105	/* Hand modified range to generic setup. */
	106	return ip_nat_setup_info(ct, &newrange, hooknum);
	107	}
	108
	109	static inline int
	110	device_cmp(struct ip_conntrack i, void ifindex)
	111	{
	112	int ret;
	113
e45b1be8	114	read_lock_bh(&masq_lock);
1da177e4	115	ret = (i->nat.masq_index == (int)(long)ifindex);
e45b1be8	116	read_unlock_bh(&masq_lock);
1da177e4 LT	117
	118	return ret;
	119	}
	120
	121	static int masq_device_event(struct notifier_block *this,
	122	unsigned long event,
	123	void *ptr)
	124	{
	125	struct net_device *dev = ptr;
	126
	127	if (event == NETDEV_DOWN) {
	128	/* Device was downed. Search entire table for
	129	conntracks which were associated with that device,
	130	and forget them. */
	131	IP_NF_ASSERT(dev->ifindex != 0);
	132
	133	ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
	134	}
	135
	136	return NOTIFY_DONE;
	137	}
	138
	139	static int masq_inet_event(struct notifier_block *this,
	140	unsigned long event,
	141	void *ptr)
	142	{
	143	struct net_device dev = ((struct in_ifaddr )ptr)->ifa_dev->dev;
	144
	145	if (event == NETDEV_DOWN) {
	146	/* IP address was deleted. Search entire table for
	147	conntracks which were associated with that device,
	148	and forget them. */
	149	IP_NF_ASSERT(dev->ifindex != 0);
	150
	151	ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
	152	}
	153
	154	return NOTIFY_DONE;
	155	}
	156
	157	static struct notifier_block masq_dev_notifier = {
	158	.notifier_call = masq_device_event,
	159	};
	160
	161	static struct notifier_block masq_inet_notifier = {
	162	.notifier_call = masq_inet_event,
	163	};
	164
	165	static struct ipt_target masquerade = {
	166	.name = "MASQUERADE",
	167	.target = masquerade_target,
1d5cd909 PM	168	.targetsize = sizeof(struct ip_nat_multi_range_compat),
	169	.table = "nat",
	170	.hooks = 1 << NF_IP_POST_ROUTING,
1da177e4 LT	171	.checkentry = masquerade_check,
	172	.me = THIS_MODULE,
	173	};
	174
65b4b4e8	175	static int __init ipt_masquerade_init(void)
1da177e4 LT	176	{
	177	int ret;
	178
	179	ret = ipt_register_target(&masquerade);
	180
	181	if (ret == 0) {
	182	/* Register for device down reports */
	183	register_netdevice_notifier(&masq_dev_notifier);
	184	/* Register IP address change reports */
	185	register_inetaddr_notifier(&masq_inet_notifier);
	186	}
	187
	188	return ret;
	189	}
	190
65b4b4e8	191	static void __exit ipt_masquerade_fini(void)
1da177e4 LT	192	{
	193	ipt_unregister_target(&masquerade);
	194	unregister_netdevice_notifier(&masq_dev_notifier);
	195	unregister_inetaddr_notifier(&masq_inet_notifier);
	196	}
	197
65b4b4e8 AM	198	module_init(ipt_masquerade_init);
65b4b4e8 AM	199	module_exit(ipt_masquerade_fini);