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.
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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/x_tables.h>
24 #include <net/netfilter/nf_nat.h>
26 MODULE_LICENSE("GPL");
27 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
28 MODULE_DESCRIPTION("Xtables: automatic-address SNAT");
30 /* FIXME: Multiple targets. --RR */
31 static int masquerade_tg_check(const struct xt_tgchk_param *par)
33 const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
35 if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) {
36 pr_debug("bad MAP_IPS.\n");
39 if (mr->rangesize != 1) {
40 pr_debug("bad rangesize %u\n", mr->rangesize);
47 masquerade_tg(struct sk_buff *skb, const struct xt_action_param *par)
50 struct nf_conn_nat *nat;
51 enum ip_conntrack_info ctinfo;
52 struct nf_nat_range newrange;
53 const struct nf_nat_ipv4_multi_range_compat *mr;
54 const struct rtable *rt;
57 NF_CT_ASSERT(par->hooknum == NF_INET_POST_ROUTING);
59 ct = nf_ct_get(skb, &ctinfo);
62 NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
63 ctinfo == IP_CT_RELATED_REPLY));
65 /* Source address is 0.0.0.0 - locally generated packet that is
66 * probably not supposed to be masqueraded.
68 if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip == 0)
73 nh = rt_nexthop(rt, ip_hdr(skb)->daddr);
74 newsrc = inet_select_addr(par->out, nh, RT_SCOPE_UNIVERSE);
76 pr_info("%s ate my IP address\n", par->out->name);
80 nat->masq_index = par->out->ifindex;
82 /* Transfer from original range. */
83 memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
84 memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
85 newrange.flags = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
86 newrange.min_addr.ip = newsrc;
87 newrange.max_addr.ip = newsrc;
88 newrange.min_proto = mr->range[0].min;
89 newrange.max_proto = mr->range[0].max;
91 /* Hand modified range to generic setup. */
92 return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC);
96 device_cmp(struct nf_conn *i, void *ifindex)
98 const struct nf_conn_nat *nat = nfct_nat(i);
102 if (nf_ct_l3num(i) != NFPROTO_IPV4)
104 return nat->masq_index == (int)(long)ifindex;
107 static int masq_device_event(struct notifier_block *this,
111 const struct net_device *dev = netdev_notifier_info_to_dev(ptr);
112 struct net *net = dev_net(dev);
114 if (event == NETDEV_DOWN) {
115 /* Device was downed. Search entire table for
116 conntracks which were associated with that device,
118 NF_CT_ASSERT(dev->ifindex != 0);
120 nf_ct_iterate_cleanup(net, device_cmp,
121 (void *)(long)dev->ifindex, 0, 0);
127 static int masq_inet_event(struct notifier_block *this,
131 struct net_device *dev = ((struct in_ifaddr *)ptr)->ifa_dev->dev;
132 struct netdev_notifier_info info;
134 netdev_notifier_info_init(&info, dev);
135 return masq_device_event(this, event, &info);
138 static struct notifier_block masq_dev_notifier = {
139 .notifier_call = masq_device_event,
142 static struct notifier_block masq_inet_notifier = {
143 .notifier_call = masq_inet_event,
146 static struct xt_target masquerade_tg_reg __read_mostly = {
147 .name = "MASQUERADE",
148 .family = NFPROTO_IPV4,
149 .target = masquerade_tg,
150 .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
152 .hooks = 1 << NF_INET_POST_ROUTING,
153 .checkentry = masquerade_tg_check,
157 static int __init masquerade_tg_init(void)
161 ret = xt_register_target(&masquerade_tg_reg);
164 /* Register for device down reports */
165 register_netdevice_notifier(&masq_dev_notifier);
166 /* Register IP address change reports */
167 register_inetaddr_notifier(&masq_inet_notifier);
173 static void __exit masquerade_tg_exit(void)
175 xt_unregister_target(&masquerade_tg_reg);
176 unregister_netdevice_notifier(&masq_dev_notifier);
177 unregister_inetaddr_notifier(&masq_inet_notifier);
180 module_init(masquerade_tg_init);
181 module_exit(masquerade_tg_exit);