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1 | /* |
2 | * (C) 1999-2001 Paul `Rusty' Russell | |
3 | * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> | |
4 | * Copyright (c) 2011 Patrick McHardy <kaber@trash.net> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | * | |
10 | * Based on Rusty Russell's IPv4 REDIRECT target. Development of IPv6 | |
11 | * NAT funded by Astaro. | |
12 | */ | |
13 | ||
14 | #include <linux/if.h> | |
15 | #include <linux/inetdevice.h> | |
16 | #include <linux/ip.h> | |
17 | #include <linux/kernel.h> | |
18 | #include <linux/module.h> | |
19 | #include <linux/netdevice.h> | |
20 | #include <linux/netfilter.h> | |
21 | #include <linux/types.h> | |
22 | #include <linux/netfilter_ipv4.h> | |
23 | #include <linux/netfilter_ipv6.h> | |
24 | #include <linux/netfilter/x_tables.h> | |
25 | #include <net/addrconf.h> | |
26 | #include <net/checksum.h> | |
27 | #include <net/protocol.h> | |
28 | #include <net/netfilter/nf_nat.h> | |
29 | ||
30 | static const struct in6_addr loopback_addr = IN6ADDR_LOOPBACK_INIT; | |
31 | ||
32 | static unsigned int | |
33 | redirect_tg6(struct sk_buff *skb, const struct xt_action_param *par) | |
34 | { | |
35 | const struct nf_nat_range *range = par->targinfo; | |
36 | struct nf_nat_range newrange; | |
37 | struct in6_addr newdst; | |
38 | enum ip_conntrack_info ctinfo; | |
39 | struct nf_conn *ct; | |
40 | ||
41 | ct = nf_ct_get(skb, &ctinfo); | |
42 | if (par->hooknum == NF_INET_LOCAL_OUT) | |
43 | newdst = loopback_addr; | |
44 | else { | |
45 | struct inet6_dev *idev; | |
46 | struct inet6_ifaddr *ifa; | |
47 | bool addr = false; | |
48 | ||
49 | rcu_read_lock(); | |
50 | idev = __in6_dev_get(skb->dev); | |
51 | if (idev != NULL) { | |
52 | list_for_each_entry(ifa, &idev->addr_list, if_list) { | |
53 | newdst = ifa->addr; | |
54 | addr = true; | |
55 | break; | |
56 | } | |
57 | } | |
58 | rcu_read_unlock(); | |
59 | ||
60 | if (!addr) | |
61 | return NF_DROP; | |
62 | } | |
63 | ||
64 | newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS; | |
65 | newrange.min_addr.in6 = newdst; | |
66 | newrange.max_addr.in6 = newdst; | |
67 | newrange.min_proto = range->min_proto; | |
68 | newrange.max_proto = range->max_proto; | |
69 | ||
70 | return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST); | |
71 | } | |
72 | ||
73 | static int redirect_tg6_checkentry(const struct xt_tgchk_param *par) | |
74 | { | |
75 | const struct nf_nat_range *range = par->targinfo; | |
76 | ||
77 | if (range->flags & NF_NAT_RANGE_MAP_IPS) | |
78 | return -EINVAL; | |
79 | return 0; | |
80 | } | |
81 | ||
82 | /* FIXME: Take multiple ranges --RR */ | |
83 | static int redirect_tg4_check(const struct xt_tgchk_param *par) | |
84 | { | |
85 | const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo; | |
86 | ||
87 | if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) { | |
88 | pr_debug("bad MAP_IPS.\n"); | |
89 | return -EINVAL; | |
90 | } | |
91 | if (mr->rangesize != 1) { | |
92 | pr_debug("bad rangesize %u.\n", mr->rangesize); | |
93 | return -EINVAL; | |
94 | } | |
95 | return 0; | |
96 | } | |
97 | ||
98 | static unsigned int | |
99 | redirect_tg4(struct sk_buff *skb, const struct xt_action_param *par) | |
100 | { | |
101 | struct nf_conn *ct; | |
102 | enum ip_conntrack_info ctinfo; | |
103 | __be32 newdst; | |
104 | const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo; | |
105 | struct nf_nat_range newrange; | |
106 | ||
107 | NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING || | |
108 | par->hooknum == NF_INET_LOCAL_OUT); | |
109 | ||
110 | ct = nf_ct_get(skb, &ctinfo); | |
111 | NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED)); | |
112 | ||
113 | /* Local packets: make them go to loopback */ | |
114 | if (par->hooknum == NF_INET_LOCAL_OUT) | |
115 | newdst = htonl(0x7F000001); | |
116 | else { | |
117 | struct in_device *indev; | |
118 | struct in_ifaddr *ifa; | |
119 | ||
120 | newdst = 0; | |
121 | ||
122 | rcu_read_lock(); | |
123 | indev = __in_dev_get_rcu(skb->dev); | |
124 | if (indev && (ifa = indev->ifa_list)) | |
125 | newdst = ifa->ifa_local; | |
126 | rcu_read_unlock(); | |
127 | ||
128 | if (!newdst) | |
129 | return NF_DROP; | |
130 | } | |
131 | ||
132 | /* Transfer from original range. */ | |
133 | memset(&newrange.min_addr, 0, sizeof(newrange.min_addr)); | |
134 | memset(&newrange.max_addr, 0, sizeof(newrange.max_addr)); | |
135 | newrange.flags = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS; | |
136 | newrange.min_addr.ip = newdst; | |
137 | newrange.max_addr.ip = newdst; | |
138 | newrange.min_proto = mr->range[0].min; | |
139 | newrange.max_proto = mr->range[0].max; | |
140 | ||
141 | /* Hand modified range to generic setup. */ | |
142 | return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST); | |
143 | } | |
144 | ||
145 | static struct xt_target redirect_tg_reg[] __read_mostly = { | |
146 | { | |
147 | .name = "REDIRECT", | |
148 | .family = NFPROTO_IPV6, | |
149 | .revision = 0, | |
150 | .table = "nat", | |
151 | .checkentry = redirect_tg6_checkentry, | |
152 | .target = redirect_tg6, | |
153 | .targetsize = sizeof(struct nf_nat_range), | |
154 | .hooks = (1 << NF_INET_PRE_ROUTING) | | |
155 | (1 << NF_INET_LOCAL_OUT), | |
156 | .me = THIS_MODULE, | |
157 | }, | |
158 | { | |
159 | .name = "REDIRECT", | |
160 | .family = NFPROTO_IPV4, | |
161 | .revision = 0, | |
162 | .table = "nat", | |
163 | .target = redirect_tg4, | |
164 | .checkentry = redirect_tg4_check, | |
165 | .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat), | |
166 | .hooks = (1 << NF_INET_PRE_ROUTING) | | |
167 | (1 << NF_INET_LOCAL_OUT), | |
168 | .me = THIS_MODULE, | |
169 | }, | |
170 | }; | |
171 | ||
172 | static int __init redirect_tg_init(void) | |
173 | { | |
174 | return xt_register_targets(redirect_tg_reg, | |
175 | ARRAY_SIZE(redirect_tg_reg)); | |
176 | } | |
177 | ||
178 | static void __exit redirect_tg_exit(void) | |
179 | { | |
180 | xt_unregister_targets(redirect_tg_reg, ARRAY_SIZE(redirect_tg_reg)); | |
181 | } | |
182 | ||
183 | module_init(redirect_tg_init); | |
184 | module_exit(redirect_tg_exit); | |
185 | ||
186 | MODULE_LICENSE("GPL"); | |
187 | MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); | |
188 | MODULE_DESCRIPTION("Xtables: Connection redirection to localhost"); | |
189 | MODULE_ALIAS("ip6t_REDIRECT"); | |
190 | MODULE_ALIAS("ipt_REDIRECT"); |