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 DECLARE_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 /* FIXME: For the moment, don't do local packets, breaks
90 testsuite for 2.3.49 --RR */
94 ct
= ip_conntrack_get(*pskb
, &ctinfo
);
95 IP_NF_ASSERT(ct
&& (ctinfo
== IP_CT_NEW
|| ctinfo
== IP_CT_RELATED
96 || ctinfo
== IP_CT_RELATED
+ IP_CT_IS_REPLY
));
99 rt
= (struct rtable
*)(*pskb
)->dst
;
100 newsrc
= inet_select_addr(out
, rt
->rt_gateway
, RT_SCOPE_UNIVERSE
);
102 printk("MASQUERADE: %s ate my IP address\n", out
->name
);
106 WRITE_LOCK(&masq_lock
);
107 ct
->nat
.masq_index
= out
->ifindex
;
108 WRITE_UNLOCK(&masq_lock
);
110 /* Transfer from original range. */
111 newrange
= ((struct ip_nat_range
)
112 { mr
->range
[0].flags
| IP_NAT_RANGE_MAP_IPS
,
114 mr
->range
[0].min
, mr
->range
[0].max
});
116 /* Hand modified range to generic setup. */
117 return ip_nat_setup_info(ct
, &newrange
, hooknum
);
121 device_cmp(struct ip_conntrack
*i
, void *ifindex
)
125 READ_LOCK(&masq_lock
);
126 ret
= (i
->nat
.masq_index
== (int)(long)ifindex
);
127 READ_UNLOCK(&masq_lock
);
132 static int masq_device_event(struct notifier_block
*this,
136 struct net_device
*dev
= ptr
;
138 if (event
== NETDEV_DOWN
) {
139 /* Device was downed. Search entire table for
140 conntracks which were associated with that device,
142 IP_NF_ASSERT(dev
->ifindex
!= 0);
144 ip_ct_iterate_cleanup(device_cmp
, (void *)(long)dev
->ifindex
);
150 static int masq_inet_event(struct notifier_block
*this,
154 struct net_device
*dev
= ((struct in_ifaddr
*)ptr
)->ifa_dev
->dev
;
156 if (event
== NETDEV_DOWN
) {
157 /* IP address was deleted. Search entire table for
158 conntracks which were associated with that device,
160 IP_NF_ASSERT(dev
->ifindex
!= 0);
162 ip_ct_iterate_cleanup(device_cmp
, (void *)(long)dev
->ifindex
);
168 static struct notifier_block masq_dev_notifier
= {
169 .notifier_call
= masq_device_event
,
172 static struct notifier_block masq_inet_notifier
= {
173 .notifier_call
= masq_inet_event
,
176 static struct ipt_target masquerade
= {
177 .name
= "MASQUERADE",
178 .target
= masquerade_target
,
179 .checkentry
= masquerade_check
,
183 static int __init
init(void)
187 ret
= ipt_register_target(&masquerade
);
190 /* Register for device down reports */
191 register_netdevice_notifier(&masq_dev_notifier
);
192 /* Register IP address change reports */
193 register_inetaddr_notifier(&masq_inet_notifier
);
199 static void __exit
fini(void)
201 ipt_unregister_target(&masquerade
);
202 unregister_netdevice_notifier(&masq_dev_notifier
);
203 unregister_inetaddr_notifier(&masq_inet_notifier
);