2 * Copyright (c) 2011, 2012 Patrick McHardy <kaber@trash.net>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
9 #include <linux/module.h>
10 #include <linux/skbuff.h>
11 #include <linux/ipv6.h>
13 #include <linux/netfilter.h>
14 #include <linux/netfilter_ipv6.h>
15 #include <linux/netfilter_ipv6/ip6t_NPT.h>
16 #include <linux/netfilter/x_tables.h>
18 static int ip6t_npt_checkentry(const struct xt_tgchk_param *par)
20 struct ip6t_npt_tginfo *npt = par->targinfo;
21 __wsum src_sum = 0, dst_sum = 0;
25 if (npt->src_pfx_len > 64 || npt->dst_pfx_len > 64)
28 /* Ensure that LSB of prefix is zero */
29 ipv6_addr_prefix(&pfx, &npt->src_pfx.in6, npt->src_pfx_len);
30 if (!ipv6_addr_equal(&pfx, &npt->src_pfx.in6))
32 ipv6_addr_prefix(&pfx, &npt->dst_pfx.in6, npt->dst_pfx_len);
33 if (!ipv6_addr_equal(&pfx, &npt->dst_pfx.in6))
36 for (i = 0; i < ARRAY_SIZE(npt->src_pfx.in6.s6_addr16); i++) {
37 src_sum = csum_add(src_sum,
38 (__force __wsum)npt->src_pfx.in6.s6_addr16[i]);
39 dst_sum = csum_add(dst_sum,
40 (__force __wsum)npt->dst_pfx.in6.s6_addr16[i]);
43 npt->adjustment = ~csum_fold(csum_sub(src_sum, dst_sum));
47 static bool ip6t_npt_map_pfx(const struct ip6t_npt_tginfo *npt,
48 struct in6_addr *addr)
55 pfx_len = max(npt->src_pfx_len, npt->dst_pfx_len);
56 for (i = 0; i < pfx_len; i += 32) {
57 if (pfx_len - i >= 32)
60 mask = htonl(~((1 << (pfx_len - i)) - 1));
63 addr->s6_addr32[idx] &= mask;
64 addr->s6_addr32[idx] |= ~mask & npt->dst_pfx.in6.s6_addr32[idx];
70 for (idx = 4; idx < ARRAY_SIZE(addr->s6_addr16); idx++) {
71 if ((__force __sum16)addr->s6_addr16[idx] !=
75 if (idx == ARRAY_SIZE(addr->s6_addr16))
79 sum = ~csum_fold(csum_add(csum_unfold((__force __sum16)addr->s6_addr16[idx]),
80 csum_unfold(npt->adjustment)));
81 if (sum == CSUM_MANGLED_0)
83 *(__force __sum16 *)&addr->s6_addr16[idx] = sum;
89 ip6t_snpt_tg(struct sk_buff *skb, const struct xt_action_param *par)
91 const struct ip6t_npt_tginfo *npt = par->targinfo;
93 if (!ip6t_npt_map_pfx(npt, &ipv6_hdr(skb)->saddr)) {
94 icmpv6_send(skb, ICMPV6_PARAMPROB, ICMPV6_HDR_FIELD,
95 offsetof(struct ipv6hdr, saddr));
102 ip6t_dnpt_tg(struct sk_buff *skb, const struct xt_action_param *par)
104 const struct ip6t_npt_tginfo *npt = par->targinfo;
106 if (!ip6t_npt_map_pfx(npt, &ipv6_hdr(skb)->daddr)) {
107 icmpv6_send(skb, ICMPV6_PARAMPROB, ICMPV6_HDR_FIELD,
108 offsetof(struct ipv6hdr, daddr));
114 static struct xt_target ip6t_npt_target_reg[] __read_mostly = {
117 .target = ip6t_snpt_tg,
118 .targetsize = sizeof(struct ip6t_npt_tginfo),
119 .checkentry = ip6t_npt_checkentry,
120 .family = NFPROTO_IPV6,
121 .hooks = (1 << NF_INET_LOCAL_IN) |
122 (1 << NF_INET_POST_ROUTING),
127 .target = ip6t_dnpt_tg,
128 .targetsize = sizeof(struct ip6t_npt_tginfo),
129 .checkentry = ip6t_npt_checkentry,
130 .family = NFPROTO_IPV6,
131 .hooks = (1 << NF_INET_PRE_ROUTING) |
132 (1 << NF_INET_LOCAL_OUT),
137 static int __init ip6t_npt_init(void)
139 return xt_register_targets(ip6t_npt_target_reg,
140 ARRAY_SIZE(ip6t_npt_target_reg));
143 static void __exit ip6t_npt_exit(void)
145 xt_unregister_targets(ip6t_npt_target_reg,
146 ARRAY_SIZE(ip6t_npt_target_reg));
149 module_init(ip6t_npt_init);
150 module_exit(ip6t_npt_exit);
152 MODULE_LICENSE("GPL");
153 MODULE_DESCRIPTION("IPv6-to-IPv6 Network Prefix Translation (RFC 6296)");
154 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
155 MODULE_ALIAS("ip6t_SNPT");
156 MODULE_ALIAS("ip6t_DNPT");