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) 2002-2006 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 <net/netfilter/nf_nat_rule.h>
23 #include <linux/netfilter_ipv4.h>
24 #include <linux/netfilter/x_tables.h>
26 MODULE_LICENSE("GPL");
27 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
28 MODULE_DESCRIPTION("Xtables: automatic-address SNAT");
30 /* Lock protects masq region inside conntrack */
31 static DEFINE_RWLOCK(masq_lock);
33 /* FIXME: Multiple targets. --RR */
35 masquerade_tg_check(const char *tablename, const void *e,
36 const struct xt_target *target, void *targinfo,
37 unsigned int hook_mask)
39 const struct nf_nat_multi_range_compat *mr = targinfo;
41 if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) {
42 pr_debug("masquerade_check: bad MAP_IPS.\n");
45 if (mr->rangesize != 1) {
46 pr_debug("masquerade_check: bad rangesize %u\n", mr->rangesize);
53 masquerade_tg(struct sk_buff *skb, const struct xt_target_param *par)
56 struct nf_conn_nat *nat;
57 enum ip_conntrack_info ctinfo;
58 struct nf_nat_range newrange;
59 const struct nf_nat_multi_range_compat *mr;
60 const struct rtable *rt;
63 NF_CT_ASSERT(par->hooknum == NF_INET_POST_ROUTING);
65 ct = nf_ct_get(skb, &ctinfo);
68 NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED
69 || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
71 /* Source address is 0.0.0.0 - locally generated packet that is
72 * probably not supposed to be masqueraded.
74 if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip == 0)
79 newsrc = inet_select_addr(par->out, rt->rt_gateway, RT_SCOPE_UNIVERSE);
81 printk("MASQUERADE: %s ate my IP address\n", par->out->name);
85 write_lock_bh(&masq_lock);
86 nat->masq_index = par->out->ifindex;
87 write_unlock_bh(&masq_lock);
89 /* Transfer from original range. */
90 newrange = ((struct nf_nat_range)
91 { mr->range[0].flags | IP_NAT_RANGE_MAP_IPS,
93 mr->range[0].min, mr->range[0].max });
95 /* Hand modified range to generic setup. */
96 return nf_nat_setup_info(ct, &newrange, IP_NAT_MANIP_SRC);
100 device_cmp(struct nf_conn *i, void *ifindex)
102 const struct nf_conn_nat *nat = nfct_nat(i);
108 read_lock_bh(&masq_lock);
109 ret = (nat->masq_index == (int)(long)ifindex);
110 read_unlock_bh(&masq_lock);
115 static int masq_device_event(struct notifier_block *this,
119 const struct net_device *dev = ptr;
120 struct net *net = dev_net(dev);
122 if (event == NETDEV_DOWN) {
123 /* Device was downed. Search entire table for
124 conntracks which were associated with that device,
126 NF_CT_ASSERT(dev->ifindex != 0);
128 nf_ct_iterate_cleanup(net, device_cmp,
129 (void *)(long)dev->ifindex);
135 static int masq_inet_event(struct notifier_block *this,
139 struct net_device *dev = ((struct in_ifaddr *)ptr)->ifa_dev->dev;
140 return masq_device_event(this, event, dev);
143 static struct notifier_block masq_dev_notifier = {
144 .notifier_call = masq_device_event,
147 static struct notifier_block masq_inet_notifier = {
148 .notifier_call = masq_inet_event,
151 static struct xt_target masquerade_tg_reg __read_mostly = {
152 .name = "MASQUERADE",
153 .family = NFPROTO_IPV4,
154 .target = masquerade_tg,
155 .targetsize = sizeof(struct nf_nat_multi_range_compat),
157 .hooks = 1 << NF_INET_POST_ROUTING,
158 .checkentry = masquerade_tg_check,
162 static int __init masquerade_tg_init(void)
166 ret = xt_register_target(&masquerade_tg_reg);
169 /* Register for device down reports */
170 register_netdevice_notifier(&masq_dev_notifier);
171 /* Register IP address change reports */
172 register_inetaddr_notifier(&masq_inet_notifier);
178 static void __exit masquerade_tg_exit(void)
180 xt_unregister_target(&masquerade_tg_reg);
181 unregister_netdevice_notifier(&masq_dev_notifier);
182 unregister_inetaddr_notifier(&masq_inet_notifier);
185 module_init(masquerade_tg_init);
186 module_exit(masquerade_tg_exit);