Commit | Line | Data |
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1da177e4 LT |
1 | /* Redirect. Simple mapping which alters dst to a local IP address. */ |
2 | /* (C) 1999-2001 Paul `Rusty' Russell | |
3 | * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org> | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License version 2 as | |
7 | * published by the Free Software Foundation. | |
8 | */ | |
9 | ||
10 | #include <linux/types.h> | |
11 | #include <linux/ip.h> | |
12 | #include <linux/timer.h> | |
13 | #include <linux/module.h> | |
14 | #include <linux/netfilter.h> | |
15 | #include <linux/netdevice.h> | |
16 | #include <linux/if.h> | |
17 | #include <linux/inetdevice.h> | |
18 | #include <net/protocol.h> | |
19 | #include <net/checksum.h> | |
20 | #include <linux/netfilter_ipv4.h> | |
21 | #include <linux/netfilter_ipv4/ip_nat_rule.h> | |
22 | ||
23 | MODULE_LICENSE("GPL"); | |
24 | MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); | |
25 | MODULE_DESCRIPTION("iptables REDIRECT target module"); | |
26 | ||
27 | #if 0 | |
28 | #define DEBUGP printk | |
29 | #else | |
30 | #define DEBUGP(format, args...) | |
31 | #endif | |
32 | ||
33 | /* FIXME: Take multiple ranges --RR */ | |
34 | static int | |
35 | redirect_check(const char *tablename, | |
36 | const struct ipt_entry *e, | |
37 | void *targinfo, | |
38 | unsigned int targinfosize, | |
39 | unsigned int hook_mask) | |
40 | { | |
41 | const struct ip_nat_multi_range_compat *mr = targinfo; | |
42 | ||
43 | if (strcmp(tablename, "nat") != 0) { | |
44 | DEBUGP("redirect_check: bad table `%s'.\n", table); | |
45 | return 0; | |
46 | } | |
47 | if (targinfosize != IPT_ALIGN(sizeof(*mr))) { | |
48 | DEBUGP("redirect_check: size %u.\n", targinfosize); | |
49 | return 0; | |
50 | } | |
51 | if (hook_mask & ~((1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_OUT))) { | |
52 | DEBUGP("redirect_check: bad hooks %x.\n", hook_mask); | |
53 | return 0; | |
54 | } | |
55 | if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) { | |
56 | DEBUGP("redirect_check: bad MAP_IPS.\n"); | |
57 | return 0; | |
58 | } | |
59 | if (mr->rangesize != 1) { | |
60 | DEBUGP("redirect_check: bad rangesize %u.\n", mr->rangesize); | |
61 | return 0; | |
62 | } | |
63 | return 1; | |
64 | } | |
65 | ||
66 | static unsigned int | |
67 | redirect_target(struct sk_buff **pskb, | |
68 | const struct net_device *in, | |
69 | const struct net_device *out, | |
70 | unsigned int hooknum, | |
71 | const void *targinfo, | |
72 | void *userinfo) | |
73 | { | |
74 | struct ip_conntrack *ct; | |
75 | enum ip_conntrack_info ctinfo; | |
76 | u_int32_t newdst; | |
77 | const struct ip_nat_multi_range_compat *mr = targinfo; | |
78 | struct ip_nat_range newrange; | |
79 | ||
80 | IP_NF_ASSERT(hooknum == NF_IP_PRE_ROUTING | |
81 | || hooknum == NF_IP_LOCAL_OUT); | |
82 | ||
83 | ct = ip_conntrack_get(*pskb, &ctinfo); | |
84 | IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED)); | |
85 | ||
86 | /* Local packets: make them go to loopback */ | |
87 | if (hooknum == NF_IP_LOCAL_OUT) | |
88 | newdst = htonl(0x7F000001); | |
89 | else { | |
90 | struct in_device *indev; | |
cd0bf2d7 | 91 | struct in_ifaddr *ifa; |
1da177e4 | 92 | |
cd0bf2d7 PM |
93 | newdst = 0; |
94 | ||
95 | rcu_read_lock(); | |
e5ed6399 | 96 | indev = __in_dev_get_rcu((*pskb)->dev); |
cd0bf2d7 PM |
97 | if (indev && (ifa = indev->ifa_list)) |
98 | newdst = ifa->ifa_local; | |
99 | rcu_read_unlock(); | |
1da177e4 | 100 | |
cd0bf2d7 PM |
101 | if (!newdst) |
102 | return NF_DROP; | |
1da177e4 LT |
103 | } |
104 | ||
105 | /* Transfer from original range. */ | |
106 | newrange = ((struct ip_nat_range) | |
107 | { mr->range[0].flags | IP_NAT_RANGE_MAP_IPS, | |
108 | newdst, newdst, | |
109 | mr->range[0].min, mr->range[0].max }); | |
110 | ||
111 | /* Hand modified range to generic setup. */ | |
112 | return ip_nat_setup_info(ct, &newrange, hooknum); | |
113 | } | |
114 | ||
115 | static struct ipt_target redirect_reg = { | |
116 | .name = "REDIRECT", | |
117 | .target = redirect_target, | |
118 | .checkentry = redirect_check, | |
119 | .me = THIS_MODULE, | |
120 | }; | |
121 | ||
122 | static int __init init(void) | |
123 | { | |
124 | return ipt_register_target(&redirect_reg); | |
125 | } | |
126 | ||
127 | static void __exit fini(void) | |
128 | { | |
129 | ipt_unregister_target(&redirect_reg); | |
130 | } | |
131 | ||
132 | module_init(init); | |
133 | module_exit(fini); |