[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/config.h>
#include <linux/types.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 <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));

	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>
	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>
	21	#include <linux/netfilter_ipv4.h>
	22	#include <linux/netfilter_ipv4/ip_nat_rule.h>
	23	#include <linux/netfilter_ipv4/ip_tables.h>
	24
	25	MODULE_LICENSE("GPL");
	26	MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
	27	MODULE_DESCRIPTION("iptables MASQUERADE target module");
	28
	29	#if 0
	30	#define DEBUGP printk
	31	#else
	32	#define DEBUGP(format, args...)
	33	#endif
	34
	35	/* Lock protects masq region inside conntrack */
e45b1be8	36	static DEFINE_RWLOCK(masq_lock);
1da177e4 LT	37
	38	/* FIXME: Multiple targets. --RR */
	39	static int
	40	masquerade_check(const char *tablename,
	41	const struct ipt_entry *e,
	42	void *targinfo,
	43	unsigned int targinfosize,
	44	unsigned int hook_mask)
	45	{
	46	const struct ip_nat_multi_range_compat *mr = targinfo;
	47
	48	if (strcmp(tablename, "nat") != 0) {
	49	DEBUGP("masquerade_check: bad table `%s'.\n", tablename);
	50	return 0;
	51	}
	52	if (targinfosize != IPT_ALIGN(sizeof(*mr))) {
	53	DEBUGP("masquerade_check: size %u != %u.\n",
	54	targinfosize, sizeof(*mr));
	55	return 0;
	56	}
	57	if (hook_mask & ~(1 << NF_IP_POST_ROUTING)) {
	58	DEBUGP("masquerade_check: bad hooks %x.\n", hook_mask);
	59	return 0;
	60	}
	61	if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) {
	62	DEBUGP("masquerade_check: bad MAP_IPS.\n");
	63	return 0;
	64	}
	65	if (mr->rangesize != 1) {
	66	DEBUGP("masquerade_check: bad rangesize %u.\n", mr->rangesize);
	67	return 0;
	68	}
	69	return 1;
	70	}
	71
	72	static unsigned int
	73	masquerade_target(struct sk_buff **pskb,
	74	const struct net_device *in,
	75	const struct net_device *out,
	76	unsigned int hooknum,
	77	const void *targinfo,
	78	void *userinfo)
	79	{
	80	struct ip_conntrack *ct;
	81	enum ip_conntrack_info ctinfo;
	82	const struct ip_nat_multi_range_compat *mr;
	83	struct ip_nat_range newrange;
	84	struct rtable *rt;
	85	u_int32_t newsrc;
	86
	87	IP_NF_ASSERT(hooknum == NF_IP_POST_ROUTING);
	88
1da177e4 LT	89	ct = ip_conntrack_get(*pskb, &ctinfo);
	90	IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW \|\| ctinfo == IP_CT_RELATED
	91	\|\| ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
	92
	93	mr = targinfo;
	94	rt = (struct rtable )(pskb)->dst;
	95	newsrc = inet_select_addr(out, rt->rt_gateway, RT_SCOPE_UNIVERSE);
	96	if (!newsrc) {
	97	printk("MASQUERADE: %s ate my IP address\n", out->name);
	98	return NF_DROP;
	99	}
	100
e45b1be8	101	write_lock_bh(&masq_lock);
1da177e4	102	ct->nat.masq_index = out->ifindex;
e45b1be8	103	write_unlock_bh(&masq_lock);
1da177e4 LT	104
	105	/* Transfer from original range. */
	106	newrange = ((struct ip_nat_range)
	107	{ mr->range[0].flags \| IP_NAT_RANGE_MAP_IPS,
	108	newsrc, newsrc,
	109	mr->range[0].min, mr->range[0].max });
	110
	111	/* Hand modified range to generic setup. */
	112	return ip_nat_setup_info(ct, &newrange, hooknum);
	113	}
	114
	115	static inline int
	116	device_cmp(struct ip_conntrack i, void ifindex)
	117	{
	118	int ret;
	119
e45b1be8	120	read_lock_bh(&masq_lock);
1da177e4	121	ret = (i->nat.masq_index == (int)(long)ifindex);
e45b1be8	122	read_unlock_bh(&masq_lock);
1da177e4 LT	123
	124	return ret;
	125	}
	126
	127	static int masq_device_event(struct notifier_block *this,
	128	unsigned long event,
	129	void *ptr)
	130	{
	131	struct net_device *dev = ptr;
	132
	133	if (event == NETDEV_DOWN) {
	134	/* Device was downed. Search entire table for
	135	conntracks which were associated with that device,
	136	and forget them. */
	137	IP_NF_ASSERT(dev->ifindex != 0);
	138
	139	ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
	140	}
	141
	142	return NOTIFY_DONE;
	143	}
	144
	145	static int masq_inet_event(struct notifier_block *this,
	146	unsigned long event,
	147	void *ptr)
	148	{
	149	struct net_device dev = ((struct in_ifaddr )ptr)->ifa_dev->dev;
	150
	151	if (event == NETDEV_DOWN) {
	152	/* IP address was deleted. Search entire table for
	153	conntracks which were associated with that device,
	154	and forget them. */
	155	IP_NF_ASSERT(dev->ifindex != 0);
	156
	157	ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
	158	}
	159
	160	return NOTIFY_DONE;
	161	}
	162
	163	static struct notifier_block masq_dev_notifier = {
	164	.notifier_call = masq_device_event,
	165	};
	166
	167	static struct notifier_block masq_inet_notifier = {
	168	.notifier_call = masq_inet_event,
	169	};
	170
	171	static struct ipt_target masquerade = {
	172	.name = "MASQUERADE",
	173	.target = masquerade_target,
	174	.checkentry = masquerade_check,
	175	.me = THIS_MODULE,
	176	};
	177
	178	static int __init init(void)
	179	{
	180	int ret;
	181
	182	ret = ipt_register_target(&masquerade);
	183
	184	if (ret == 0) {
	185	/* Register for device down reports */
	186	register_netdevice_notifier(&masq_dev_notifier);
187	/* Register IP address change reports */
188	register_inetaddr_notifier(&masq_inet_notifier);
189	}
190
191	return ret;
192	}
193
194	static void __exit fini(void)
195	{
196	ipt_unregister_target(&masquerade);
197	unregister_netdevice_notifier(&masq_dev_notifier);
198	unregister_inetaddr_notifier(&masq_inet_notifier);
199	}
200
201	module_init(init);
202	module_exit(fini);