1 /* Masquerade. Simple mapping which alters range to a local IP address
2 (depending on route). */
3
4 /* (C) 1999-2001 Paul `Rusty' Russell
5 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
6 *
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.
10 */
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12 #include <linux/types.h>
13 #include <linux/inetdevice.h>
14 #include <linux/ip.h>
15 #include <linux/timer.h>
16 #include <linux/module.h>
17 #include <linux/netfilter.h>
18 #include <net/protocol.h>
19 #include <net/ip.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>
25 #include <net/netfilter/ipv4/nf_nat_masquerade.h>
26
27 MODULE_LICENSE("GPL");
28 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
29 MODULE_DESCRIPTION("Xtables: automatic-address SNAT");
30
31 /* FIXME: Multiple targets. --RR */
32 static int masquerade_tg_check(const struct xt_tgchk_param *par)
33 {
34 const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
35
36 if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) {
37 pr_debug("bad MAP_IPS.\n");
38 return -EINVAL;
39 }
40 if (mr->rangesize != 1) {
41 pr_debug("bad rangesize %u\n", mr->rangesize);
42 return -EINVAL;
43 }
44 return 0;
45 }
46
47 static unsigned int
48 masquerade_tg(struct sk_buff *skb, const struct xt_action_param *par)
49 {
50 struct nf_nat_range range;
51 const struct nf_nat_ipv4_multi_range_compat *mr;
52
53 mr = par->targinfo;
54 range.flags = mr->range[0].flags;
55 range.min_proto = mr->range[0].min;
56 range.max_proto = mr->range[0].max;
57
58 return nf_nat_masquerade_ipv4(skb, par->hooknum, &range, par->out);
59 }
60
61 static struct xt_target masquerade_tg_reg __read_mostly = {
62 .name = "MASQUERADE",
63 .family = NFPROTO_IPV4,
64 .target = masquerade_tg,
65 .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
66 .table = "nat",
67 .hooks = 1 << NF_INET_POST_ROUTING,
68 .checkentry = masquerade_tg_check,
69 .me = THIS_MODULE,
70 };
71
72 static int __init masquerade_tg_init(void)
73 {
74 int ret;
75
76 ret = xt_register_target(&masquerade_tg_reg);
77
78 if (ret == 0)
79 nf_nat_masquerade_ipv4_register_notifier();
80
81 return ret;
82 }
83
84 static void __exit masquerade_tg_exit(void)
85 {
86 xt_unregister_target(&masquerade_tg_reg);
87 nf_nat_masquerade_ipv4_unregister_notifier();
88 }
89
90 module_init(masquerade_tg_init);
91 module_exit(masquerade_tg_exit);
92
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