1 /* Masquerade. Simple mapping which alters range to a local IP address
2 (depending on route). */
4 /* (C) 1999-2001 Paul `Rusty' Russell
5 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
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.
12 #include <linux/types.h>
13 #include <linux/inetdevice.h>
15 #include <linux/timer.h>
16 #include <linux/module.h>
17 #include <linux/netfilter.h>
18 #include <net/protocol.h>
20 #include <net/checksum.h>
21 #include <net/route.h>
22 #include <linux/netfilter_ipv4.h>
23 #include <linux/netfilter_ipv4/ip_nat_rule.h>
24 #include <linux/netfilter_ipv4/ip_tables.h>
26 MODULE_LICENSE("GPL");
27 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
28 MODULE_DESCRIPTION("iptables MASQUERADE target module");
33 #define DEBUGP(format, args...)
36 /* Lock protects masq region inside conntrack */
37 static DEFINE_RWLOCK(masq_lock);
39 /* FIXME: Multiple targets. --RR */
41 masquerade_check(const char *tablename,
43 const struct xt_target *target,
45 unsigned int targinfosize,
46 unsigned int hook_mask)
48 const struct ip_nat_multi_range_compat *mr = targinfo;
50 if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) {
51 DEBUGP("masquerade_check: bad MAP_IPS.\n");
54 if (mr->rangesize != 1) {
55 DEBUGP("masquerade_check: bad rangesize %u.\n", mr->rangesize);
62 masquerade_target(struct sk_buff **pskb,
63 const struct net_device *in,
64 const struct net_device *out,
66 const struct xt_target *target,
70 struct ip_conntrack *ct;
71 enum ip_conntrack_info ctinfo;
72 const struct ip_nat_multi_range_compat *mr;
73 struct ip_nat_range newrange;
77 IP_NF_ASSERT(hooknum == NF_IP_POST_ROUTING);
79 ct = ip_conntrack_get(*pskb, &ctinfo);
80 IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED
81 || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
83 /* Source address is 0.0.0.0 - locally generated packet that is
84 * probably not supposed to be masqueraded.
86 if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip == 0)
90 rt = (struct rtable *)(*pskb)->dst;
91 newsrc = inet_select_addr(out, rt->rt_gateway, RT_SCOPE_UNIVERSE);
93 printk("MASQUERADE: %s ate my IP address\n", out->name);
97 write_lock_bh(&masq_lock);
98 ct->nat.masq_index = out->ifindex;
99 write_unlock_bh(&masq_lock);
101 /* Transfer from original range. */
102 newrange = ((struct ip_nat_range)
103 { mr->range[0].flags | IP_NAT_RANGE_MAP_IPS,
105 mr->range[0].min, mr->range[0].max });
107 /* Hand modified range to generic setup. */
108 return ip_nat_setup_info(ct, &newrange, hooknum);
112 device_cmp(struct ip_conntrack *i, void *ifindex)
116 read_lock_bh(&masq_lock);
117 ret = (i->nat.masq_index == (int)(long)ifindex);
118 read_unlock_bh(&masq_lock);
123 static int masq_device_event(struct notifier_block *this,
127 struct net_device *dev = ptr;
129 if (event == NETDEV_DOWN) {
130 /* Device was downed. Search entire table for
131 conntracks which were associated with that device,
133 IP_NF_ASSERT(dev->ifindex != 0);
135 ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
141 static int masq_inet_event(struct notifier_block *this,
145 struct net_device *dev = ((struct in_ifaddr *)ptr)->ifa_dev->dev;
147 if (event == NETDEV_DOWN) {
148 /* IP address was deleted. Search entire table for
149 conntracks which were associated with that device,
151 IP_NF_ASSERT(dev->ifindex != 0);
153 ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
159 static struct notifier_block masq_dev_notifier = {
160 .notifier_call = masq_device_event,
163 static struct notifier_block masq_inet_notifier = {
164 .notifier_call = masq_inet_event,
167 static struct ipt_target masquerade = {
168 .name = "MASQUERADE",
169 .target = masquerade_target,
170 .targetsize = sizeof(struct ip_nat_multi_range_compat),
172 .hooks = 1 << NF_IP_POST_ROUTING,
173 .checkentry = masquerade_check,
177 static int __init ipt_masquerade_init(void)
181 ret = ipt_register_target(&masquerade);
184 /* Register for device down reports */
185 register_netdevice_notifier(&masq_dev_notifier);
186 /* Register IP address change reports */
187 register_inetaddr_notifier(&masq_inet_notifier);
193 static void __exit ipt_masquerade_fini(void)
195 ipt_unregister_target(&masquerade);
196 unregister_netdevice_notifier(&masq_dev_notifier);
197 unregister_inetaddr_notifier(&masq_inet_notifier);
200 module_init(ipt_masquerade_init);
201 module_exit(ipt_masquerade_fini);