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/config.h>
13 #include <linux/types.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 <linux/netfilter_ipv4.h>
22 #include <linux/netfilter_ipv4/ip_nat_rule.h>
23 #include <linux/netfilter_ipv4/ip_tables.h>
25 MODULE_LICENSE("GPL");
26 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
27 MODULE_DESCRIPTION("iptables MASQUERADE target module");
32 #define DEBUGP(format, args...)
35 /* Lock protects masq region inside conntrack */
36 static DEFINE_RWLOCK(masq_lock);
38 /* FIXME: Multiple targets. --RR */
40 masquerade_check(const char *tablename,
41 const struct ipt_entry *e,
43 unsigned int targinfosize,
44 unsigned int hook_mask)
46 const struct ip_nat_multi_range_compat *mr = targinfo;
48 if (strcmp(tablename, "nat") != 0) {
49 DEBUGP("masquerade_check: bad table `%s'.\n", tablename);
52 if (targinfosize != IPT_ALIGN(sizeof(*mr))) {
53 DEBUGP("masquerade_check: size %u != %u.\n",
54 targinfosize, sizeof(*mr));
57 if (hook_mask & ~(1 << NF_IP_POST_ROUTING)) {
58 DEBUGP("masquerade_check: bad hooks %x.\n", hook_mask);
61 if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) {
62 DEBUGP("masquerade_check: bad MAP_IPS.\n");
65 if (mr->rangesize != 1) {
66 DEBUGP("masquerade_check: bad rangesize %u.\n", mr->rangesize);
73 masquerade_target(struct sk_buff **pskb,
74 const struct net_device *in,
75 const struct net_device *out,
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;
87 IP_NF_ASSERT(hooknum == NF_IP_POST_ROUTING);
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));
94 rt = (struct rtable *)(*pskb)->dst;
95 newsrc = inet_select_addr(out, rt->rt_gateway, RT_SCOPE_UNIVERSE);
97 printk("MASQUERADE: %s ate my IP address\n", out->name);
101 write_lock_bh(&masq_lock);
102 ct->nat.masq_index = out->ifindex;
103 write_unlock_bh(&masq_lock);
105 /* Transfer from original range. */
106 newrange = ((struct ip_nat_range)
107 { mr->range[0].flags | IP_NAT_RANGE_MAP_IPS,
109 mr->range[0].min, mr->range[0].max });
111 /* Hand modified range to generic setup. */
112 return ip_nat_setup_info(ct, &newrange, hooknum);
116 device_cmp(struct ip_conntrack *i, void *ifindex)
120 read_lock_bh(&masq_lock);
121 ret = (i->nat.masq_index == (int)(long)ifindex);
122 read_unlock_bh(&masq_lock);
127 static int masq_device_event(struct notifier_block *this,
131 struct net_device *dev = ptr;
133 if (event == NETDEV_DOWN) {
134 /* Device was downed. Search entire table for
135 conntracks which were associated with that device,
137 IP_NF_ASSERT(dev->ifindex != 0);
139 ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
145 static int masq_inet_event(struct notifier_block *this,
149 struct net_device *dev = ((struct in_ifaddr *)ptr)->ifa_dev->dev;
151 if (event == NETDEV_DOWN) {
152 /* IP address was deleted. Search entire table for
153 conntracks which were associated with that device,
155 IP_NF_ASSERT(dev->ifindex != 0);
157 ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
163 static struct notifier_block masq_dev_notifier = {
164 .notifier_call = masq_device_event,
167 static struct notifier_block masq_inet_notifier = {
168 .notifier_call = masq_inet_event,
171 static struct ipt_target masquerade = {
172 .name = "MASQUERADE",
173 .target = masquerade_target,
174 .checkentry = masquerade_check,
178 static int __init init(void)
182 ret = ipt_register_target(&masquerade);
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);
194 static void __exit fini(void)
196 ipt_unregister_target(&masquerade);
197 unregister_netdevice_notifier(&masq_dev_notifier);
198 unregister_inetaddr_notifier(&masq_inet_notifier);