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
= 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
);
127 static int masq_inet_event(struct notifier_block
*this,
131 struct net_device
*dev
= ((struct in_ifaddr
*)ptr
)->ifa_dev
->dev
;
132 return masq_device_event(this, event
, dev
);
135 static struct notifier_block masq_dev_notifier
= {
136 .notifier_call
= masq_device_event
,
139 static struct notifier_block masq_inet_notifier
= {
140 .notifier_call
= masq_inet_event
,
143 static struct xt_target masquerade_tg_reg __read_mostly
= {
144 .name
= "MASQUERADE",
145 .family
= NFPROTO_IPV4
,
146 .target
= masquerade_tg
,
147 .targetsize
= sizeof(struct nf_nat_ipv4_multi_range_compat
),
149 .hooks
= 1 << NF_INET_POST_ROUTING
,
150 .checkentry
= masquerade_tg_check
,
154 static int __init
masquerade_tg_init(void)
158 ret
= xt_register_target(&masquerade_tg_reg
);
161 /* Register for device down reports */
162 register_netdevice_notifier(&masq_dev_notifier
);
163 /* Register IP address change reports */
164 register_inetaddr_notifier(&masq_inet_notifier
);
170 static void __exit
masquerade_tg_exit(void)
172 xt_unregister_target(&masquerade_tg_reg
);
173 unregister_netdevice_notifier(&masq_dev_notifier
);
174 unregister_inetaddr_notifier(&masq_inet_notifier
);
177 module_init(masquerade_tg_init
);
178 module_exit(masquerade_tg_exit
);