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8a91bb0c PM |
1 | /* |
2 | * Copyright (c) 2011, 2012 Patrick McHardy <kaber@trash.net> | |
3 | * | |
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. | |
7 | */ | |
8 | ||
9 | #include <linux/module.h> | |
10 | #include <linux/skbuff.h> | |
11 | #include <linux/ipv6.h> | |
edb27228 | 12 | #include <net/ipv6.h> |
8a91bb0c PM |
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> | |
17 | ||
8a91bb0c PM |
18 | static int ip6t_npt_checkentry(const struct xt_tgchk_param *par) |
19 | { | |
20 | struct ip6t_npt_tginfo *npt = par->targinfo; | |
edb27228 | 21 | struct in6_addr pfx; |
2d2fd8c5 | 22 | __wsum src_sum, dst_sum; |
8a91bb0c PM |
23 | |
24 | if (npt->src_pfx_len > 64 || npt->dst_pfx_len > 64) | |
25 | return -EINVAL; | |
26 | ||
edb27228 YH |
27 | /* Ensure that LSB of prefix is zero */ |
28 | ipv6_addr_prefix(&pfx, &npt->src_pfx.in6, npt->src_pfx_len); | |
29 | if (!ipv6_addr_equal(&pfx, &npt->src_pfx.in6)) | |
30 | return -EINVAL; | |
31 | ipv6_addr_prefix(&pfx, &npt->dst_pfx.in6, npt->dst_pfx_len); | |
32 | if (!ipv6_addr_equal(&pfx, &npt->dst_pfx.in6)) | |
33 | return -EINVAL; | |
34 | ||
2d2fd8c5 YH |
35 | src_sum = csum_partial(&npt->src_pfx.in6, sizeof(npt->src_pfx.in6), 0); |
36 | dst_sum = csum_partial(&npt->dst_pfx.in6, sizeof(npt->dst_pfx.in6), 0); | |
8a91bb0c | 37 | |
f5271fff | 38 | npt->adjustment = ~csum_fold(csum_sub(src_sum, dst_sum)); |
8a91bb0c PM |
39 | return 0; |
40 | } | |
41 | ||
42 | static bool ip6t_npt_map_pfx(const struct ip6t_npt_tginfo *npt, | |
43 | struct in6_addr *addr) | |
44 | { | |
45 | unsigned int pfx_len; | |
46 | unsigned int i, idx; | |
47 | __be32 mask; | |
48 | __sum16 sum; | |
49 | ||
50 | pfx_len = max(npt->src_pfx_len, npt->dst_pfx_len); | |
51 | for (i = 0; i < pfx_len; i += 32) { | |
52 | if (pfx_len - i >= 32) | |
53 | mask = 0; | |
54 | else | |
906b1c39 | 55 | mask = htonl((1 << (i - pfx_len + 32)) - 1); |
8a91bb0c PM |
56 | |
57 | idx = i / 32; | |
58 | addr->s6_addr32[idx] &= mask; | |
d4c38fa8 | 59 | addr->s6_addr32[idx] |= ~mask & npt->dst_pfx.in6.s6_addr32[idx]; |
8a91bb0c PM |
60 | } |
61 | ||
62 | if (pfx_len <= 48) | |
63 | idx = 3; | |
64 | else { | |
65 | for (idx = 4; idx < ARRAY_SIZE(addr->s6_addr16); idx++) { | |
66 | if ((__force __sum16)addr->s6_addr16[idx] != | |
67 | CSUM_MANGLED_0) | |
68 | break; | |
69 | } | |
70 | if (idx == ARRAY_SIZE(addr->s6_addr16)) | |
71 | return false; | |
72 | } | |
73 | ||
f5271fff YH |
74 | sum = ~csum_fold(csum_add(csum_unfold((__force __sum16)addr->s6_addr16[idx]), |
75 | csum_unfold(npt->adjustment))); | |
8a91bb0c PM |
76 | if (sum == CSUM_MANGLED_0) |
77 | sum = 0; | |
78 | *(__force __sum16 *)&addr->s6_addr16[idx] = sum; | |
79 | ||
80 | return true; | |
81 | } | |
82 | ||
83 | static unsigned int | |
84 | ip6t_snpt_tg(struct sk_buff *skb, const struct xt_action_param *par) | |
85 | { | |
86 | const struct ip6t_npt_tginfo *npt = par->targinfo; | |
87 | ||
88 | if (!ip6t_npt_map_pfx(npt, &ipv6_hdr(skb)->saddr)) { | |
89 | icmpv6_send(skb, ICMPV6_PARAMPROB, ICMPV6_HDR_FIELD, | |
90 | offsetof(struct ipv6hdr, saddr)); | |
91 | return NF_DROP; | |
92 | } | |
93 | return XT_CONTINUE; | |
94 | } | |
95 | ||
96 | static unsigned int | |
97 | ip6t_dnpt_tg(struct sk_buff *skb, const struct xt_action_param *par) | |
98 | { | |
99 | const struct ip6t_npt_tginfo *npt = par->targinfo; | |
100 | ||
101 | if (!ip6t_npt_map_pfx(npt, &ipv6_hdr(skb)->daddr)) { | |
102 | icmpv6_send(skb, ICMPV6_PARAMPROB, ICMPV6_HDR_FIELD, | |
103 | offsetof(struct ipv6hdr, daddr)); | |
104 | return NF_DROP; | |
105 | } | |
106 | return XT_CONTINUE; | |
107 | } | |
108 | ||
109 | static struct xt_target ip6t_npt_target_reg[] __read_mostly = { | |
110 | { | |
111 | .name = "SNPT", | |
a82783c9 | 112 | .table = "mangle", |
8a91bb0c PM |
113 | .target = ip6t_snpt_tg, |
114 | .targetsize = sizeof(struct ip6t_npt_tginfo), | |
115 | .checkentry = ip6t_npt_checkentry, | |
116 | .family = NFPROTO_IPV6, | |
117 | .hooks = (1 << NF_INET_LOCAL_IN) | | |
118 | (1 << NF_INET_POST_ROUTING), | |
119 | .me = THIS_MODULE, | |
120 | }, | |
121 | { | |
122 | .name = "DNPT", | |
a82783c9 | 123 | .table = "mangle", |
8a91bb0c PM |
124 | .target = ip6t_dnpt_tg, |
125 | .targetsize = sizeof(struct ip6t_npt_tginfo), | |
126 | .checkentry = ip6t_npt_checkentry, | |
127 | .family = NFPROTO_IPV6, | |
128 | .hooks = (1 << NF_INET_PRE_ROUTING) | | |
129 | (1 << NF_INET_LOCAL_OUT), | |
130 | .me = THIS_MODULE, | |
131 | }, | |
132 | }; | |
133 | ||
134 | static int __init ip6t_npt_init(void) | |
135 | { | |
136 | return xt_register_targets(ip6t_npt_target_reg, | |
137 | ARRAY_SIZE(ip6t_npt_target_reg)); | |
138 | } | |
139 | ||
140 | static void __exit ip6t_npt_exit(void) | |
141 | { | |
142 | xt_unregister_targets(ip6t_npt_target_reg, | |
143 | ARRAY_SIZE(ip6t_npt_target_reg)); | |
144 | } | |
145 | ||
146 | module_init(ip6t_npt_init); | |
147 | module_exit(ip6t_npt_exit); | |
148 | ||
149 | MODULE_LICENSE("GPL"); | |
150 | MODULE_DESCRIPTION("IPv6-to-IPv6 Network Prefix Translation (RFC 6296)"); | |
151 | MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); | |
152 | MODULE_ALIAS("ip6t_SNPT"); | |
153 | MODULE_ALIAS("ip6t_DNPT"); |