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>
14 #include <linux/inetdevice.h>
16 #include <linux/timer.h>
17 #include <linux/module.h>
18 #include <linux/netfilter.h>
19 #include <net/protocol.h>
21 #include <net/checksum.h>
22 #include <net/route.h>
23 #include <linux/netfilter_ipv4.h>
24 #include <linux/netfilter_ipv4/ip_nat_rule.h>
25 #include <linux/netfilter_ipv4/ip_tables.h>
27 MODULE_LICENSE("GPL");
28 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
29 MODULE_DESCRIPTION("iptables MASQUERADE target module");
34 #define DEBUGP(format, args...)
37 /* Lock protects masq region inside conntrack */
38 static DEFINE_RWLOCK(masq_lock);
40 /* FIXME: Multiple targets. --RR */
42 masquerade_check(const char *tablename,
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,
69 struct ip_conntrack *ct;
70 enum ip_conntrack_info ctinfo;
71 const struct ip_nat_multi_range_compat *mr;
72 struct ip_nat_range newrange;
76 IP_NF_ASSERT(hooknum == NF_IP_POST_ROUTING);
78 ct = ip_conntrack_get(*pskb, &ctinfo);
79 IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED
80 || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
82 /* Source address is 0.0.0.0 - locally generated packet that is
83 * probably not supposed to be masqueraded.
85 if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip == 0)
89 rt = (struct rtable *)(*pskb)->dst;
90 newsrc = inet_select_addr(out, rt->rt_gateway, RT_SCOPE_UNIVERSE);
92 printk("MASQUERADE: %s ate my IP address\n", out->name);
96 write_lock_bh(&masq_lock);
97 ct->nat.masq_index = out->ifindex;
98 write_unlock_bh(&masq_lock);
100 /* Transfer from original range. */
101 newrange = ((struct ip_nat_range)
102 { mr->range[0].flags | IP_NAT_RANGE_MAP_IPS,
104 mr->range[0].min, mr->range[0].max });
106 /* Hand modified range to generic setup. */
107 return ip_nat_setup_info(ct, &newrange, hooknum);
111 device_cmp(struct ip_conntrack *i, void *ifindex)
115 read_lock_bh(&masq_lock);
116 ret = (i->nat.masq_index == (int)(long)ifindex);
117 read_unlock_bh(&masq_lock);
122 static int masq_device_event(struct notifier_block *this,
126 struct net_device *dev = ptr;
128 if (event == NETDEV_DOWN) {
129 /* Device was downed. Search entire table for
130 conntracks which were associated with that device,
132 IP_NF_ASSERT(dev->ifindex != 0);
134 ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
140 static int masq_inet_event(struct notifier_block *this,
144 struct net_device *dev = ((struct in_ifaddr *)ptr)->ifa_dev->dev;
146 if (event == NETDEV_DOWN) {
147 /* IP address was deleted. Search entire table for
148 conntracks which were associated with that device,
150 IP_NF_ASSERT(dev->ifindex != 0);
152 ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
158 static struct notifier_block masq_dev_notifier = {
159 .notifier_call = masq_device_event,
162 static struct notifier_block masq_inet_notifier = {
163 .notifier_call = masq_inet_event,
166 static struct ipt_target masquerade = {
167 .name = "MASQUERADE",
168 .target = masquerade_target,
169 .targetsize = sizeof(struct ip_nat_multi_range_compat),
171 .hooks = 1 << NF_IP_POST_ROUTING,
172 .checkentry = masquerade_check,
176 static int __init init(void)
180 ret = ipt_register_target(&masquerade);
183 /* Register for device down reports */
184 register_netdevice_notifier(&masq_dev_notifier);
185 /* Register IP address change reports */
186 register_inetaddr_notifier(&masq_inet_notifier);
192 static void __exit fini(void)
194 ipt_unregister_target(&masquerade);
195 unregister_netdevice_notifier(&masq_dev_notifier);
196 unregister_inetaddr_notifier(&masq_inet_notifier);