[linux-block.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 DECLARE_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);

	/* FIXME: For the moment, don't do local packets, breaks
	   testsuite for 2.3.49 --RR */
	if ((*pskb)->sk)
		return NF_ACCEPT;

	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(&masq_lock);
	ct->nat.masq_index = out->ifindex;
	WRITE_UNLOCK(&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(&masq_lock);
	ret = (i->nat.masq_index == (int)(long)ifindex);
	READ_UNLOCK(&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 */
	36	static DECLARE_RWLOCK(masq_lock);
	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
89	/* FIXME: For the moment, don't do local packets, breaks
90	testsuite for 2.3.49 --RR */
91	if ((*pskb)->sk)
92	return NF_ACCEPT;
93
94	ct = ip_conntrack_get(*pskb, &ctinfo);
95	IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW \|\| ctinfo == IP_CT_RELATED
96	\|\| ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
97
98	mr = targinfo;
99	rt = (struct rtable )(pskb)->dst;
100	newsrc = inet_select_addr(out, rt->rt_gateway, RT_SCOPE_UNIVERSE);
101	if (!newsrc) {
102	printk("MASQUERADE: %s ate my IP address\n", out->name);
103	return NF_DROP;
104	}
105
106	WRITE_LOCK(&masq_lock);
107	ct->nat.masq_index = out->ifindex;
108	WRITE_UNLOCK(&masq_lock);
109
110	/* Transfer from original range. */
111	newrange = ((struct ip_nat_range)
112	{ mr->range[0].flags \| IP_NAT_RANGE_MAP_IPS,
113	newsrc, newsrc,
114	mr->range[0].min, mr->range[0].max });
115
116	/* Hand modified range to generic setup. */
117	return ip_nat_setup_info(ct, &newrange, hooknum);
118	}
119
120	static inline int
121	device_cmp(struct ip_conntrack i, void ifindex)
122	{
123	int ret;
124
125	READ_LOCK(&masq_lock);
126	ret = (i->nat.masq_index == (int)(long)ifindex);
127	READ_UNLOCK(&masq_lock);
128
129	return ret;
130	}
131
132	static int masq_device_event(struct notifier_block *this,
133	unsigned long event,
134	void *ptr)
135	{
136	struct net_device *dev = ptr;
137
138	if (event == NETDEV_DOWN) {
139	/* Device was downed. Search entire table for
140	conntracks which were associated with that device,
141	and forget them. */
142	IP_NF_ASSERT(dev->ifindex != 0);
143
144	ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
145	}
146
147	return NOTIFY_DONE;
148	}
149
150	static int masq_inet_event(struct notifier_block *this,
151	unsigned long event,
152	void *ptr)
153	{
154	struct net_device dev = ((struct in_ifaddr )ptr)->ifa_dev->dev;
155
156	if (event == NETDEV_DOWN) {
157	/* IP address was deleted. Search entire table for
158	conntracks which were associated with that device,
159	and forget them. */
160	IP_NF_ASSERT(dev->ifindex != 0);
161
162	ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
163	}
164
165	return NOTIFY_DONE;
166	}
167
168	static struct notifier_block masq_dev_notifier = {
169	.notifier_call = masq_device_event,
170	};
171
172	static struct notifier_block masq_inet_notifier = {
173	.notifier_call = masq_inet_event,
174	};
175
176	static struct ipt_target masquerade = {
177	.name = "MASQUERADE",
178	.target = masquerade_target,
179	.checkentry = masquerade_check,
180	.me = THIS_MODULE,
181	};
182
183	static int __init init(void)
184	{
185	int ret;
186
187	ret = ipt_register_target(&masquerade);
188
189	if (ret == 0) {
190	/* Register for device down reports */
191	register_netdevice_notifier(&masq_dev_notifier);
192	/* Register IP address change reports */
193	register_inetaddr_notifier(&masq_inet_notifier);
194	}
195
196	return ret;
197	}
198
199	static void __exit fini(void)
200	{
201	ipt_unregister_target(&masquerade);
202	unregister_netdevice_notifier(&masq_dev_notifier);
203	unregister_inetaddr_notifier(&masq_inet_notifier);
204	}
205
206	module_init(init);
207	module_exit(fini);