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("iptables MASQUERADE target module");
30 /* Lock protects masq region inside conntrack */
31 static DEFINE_RWLOCK(masq_lock
);
33 /* FIXME: Multiple targets. --RR */
35 masquerade_check(const char *tablename
,
37 const struct xt_target
*target
,
39 unsigned int hook_mask
)
41 const struct nf_nat_multi_range_compat
*mr
= targinfo
;
43 if (mr
->range
[0].flags
& IP_NAT_RANGE_MAP_IPS
) {
44 pr_debug("masquerade_check: bad MAP_IPS.\n");
47 if (mr
->rangesize
!= 1) {
48 pr_debug("masquerade_check: bad rangesize %u\n", mr
->rangesize
);
55 masquerade_target(struct sk_buff
**pskb
,
56 const struct net_device
*in
,
57 const struct net_device
*out
,
59 const struct xt_target
*target
,
63 struct nf_conn_nat
*nat
;
64 enum ip_conntrack_info ctinfo
;
65 struct nf_nat_range newrange
;
66 const struct nf_nat_multi_range_compat
*mr
;
67 const struct rtable
*rt
;
70 NF_CT_ASSERT(hooknum
== NF_IP_POST_ROUTING
);
72 ct
= nf_ct_get(*pskb
, &ctinfo
);
75 NF_CT_ASSERT(ct
&& (ctinfo
== IP_CT_NEW
|| ctinfo
== IP_CT_RELATED
76 || ctinfo
== IP_CT_RELATED
+ IP_CT_IS_REPLY
));
78 /* Source address is 0.0.0.0 - locally generated packet that is
79 * probably not supposed to be masqueraded.
81 if (ct
->tuplehash
[IP_CT_DIR_ORIGINAL
].tuple
.src
.u3
.ip
== 0)
85 rt
= (struct rtable
*)(*pskb
)->dst
;
86 newsrc
= inet_select_addr(out
, rt
->rt_gateway
, RT_SCOPE_UNIVERSE
);
88 printk("MASQUERADE: %s ate my IP address\n", out
->name
);
92 write_lock_bh(&masq_lock
);
93 nat
->masq_index
= out
->ifindex
;
94 write_unlock_bh(&masq_lock
);
96 /* Transfer from original range. */
97 newrange
= ((struct nf_nat_range
)
98 { mr
->range
[0].flags
| IP_NAT_RANGE_MAP_IPS
,
100 mr
->range
[0].min
, mr
->range
[0].max
});
102 /* Hand modified range to generic setup. */
103 return nf_nat_setup_info(ct
, &newrange
, hooknum
);
107 device_cmp(struct nf_conn
*i
, void *ifindex
)
109 const struct nf_conn_nat
*nat
= nfct_nat(i
);
115 read_lock_bh(&masq_lock
);
116 ret
= (nat
->masq_index
== (int)(long)ifindex
);
117 read_unlock_bh(&masq_lock
);
122 static int masq_device_event(struct notifier_block
*this,
126 const 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 NF_CT_ASSERT(dev
->ifindex
!= 0);
134 nf_ct_iterate_cleanup(device_cmp
, (void *)(long)dev
->ifindex
);
140 static int masq_inet_event(struct notifier_block
*this,
144 const 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 NF_CT_ASSERT(dev
->ifindex
!= 0);
152 nf_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 xt_target masquerade __read_mostly
= {
167 .name
= "MASQUERADE",
169 .target
= masquerade_target
,
170 .targetsize
= sizeof(struct nf_nat_multi_range_compat
),
172 .hooks
= 1 << NF_IP_POST_ROUTING
,
173 .checkentry
= masquerade_check
,
177 static int __init
ipt_masquerade_init(void)
181 ret
= xt_register_target(&masquerade
);
184 /* Register for device down reports */
185 register_netdevice_notifier(&masq_dev_notifier
);
186 /* Register IP address change reports */
187 register_inetaddr_notifier(&masq_inet_notifier
);
193 static void __exit
ipt_masquerade_fini(void)
195 xt_unregister_target(&masquerade
);
196 unregister_netdevice_notifier(&masq_dev_notifier
);
197 unregister_inetaddr_notifier(&masq_inet_notifier
);
200 module_init(ipt_masquerade_init
);
201 module_exit(ipt_masquerade_fini
);