87b759c11da573f56a5010ef570618cd1f097512
[~shefty/rdma-dev.git] / net / ipv6 / netfilter / ip6t_NPT.c
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>
12 #include <linux/netfilter.h>
13 #include <linux/netfilter_ipv6.h>
14 #include <linux/netfilter_ipv6/ip6t_NPT.h>
15 #include <linux/netfilter/x_tables.h>
16
17 static int ip6t_npt_checkentry(const struct xt_tgchk_param *par)
18 {
19         struct ip6t_npt_tginfo *npt = par->targinfo;
20         __wsum src_sum = 0, dst_sum = 0;
21         unsigned int i;
22
23         if (npt->src_pfx_len > 64 || npt->dst_pfx_len > 64)
24                 return -EINVAL;
25
26         for (i = 0; i < ARRAY_SIZE(npt->src_pfx.in6.s6_addr16); i++) {
27                 src_sum = csum_add(src_sum,
28                                 (__force __wsum)npt->src_pfx.in6.s6_addr16[i]);
29                 dst_sum = csum_add(dst_sum,
30                                 (__force __wsum)npt->dst_pfx.in6.s6_addr16[i]);
31         }
32
33         npt->adjustment = ~csum_fold(csum_sub(src_sum, dst_sum));
34         return 0;
35 }
36
37 static bool ip6t_npt_map_pfx(const struct ip6t_npt_tginfo *npt,
38                              struct in6_addr *addr)
39 {
40         unsigned int pfx_len;
41         unsigned int i, idx;
42         __be32 mask;
43         __sum16 sum;
44
45         pfx_len = max(npt->src_pfx_len, npt->dst_pfx_len);
46         for (i = 0; i < pfx_len; i += 32) {
47                 if (pfx_len - i >= 32)
48                         mask = 0;
49                 else
50                         mask = htonl(~((1 << (pfx_len - i)) - 1));
51
52                 idx = i / 32;
53                 addr->s6_addr32[idx] &= mask;
54                 addr->s6_addr32[idx] |= ~mask & npt->dst_pfx.in6.s6_addr32[idx];
55         }
56
57         if (pfx_len <= 48)
58                 idx = 3;
59         else {
60                 for (idx = 4; idx < ARRAY_SIZE(addr->s6_addr16); idx++) {
61                         if ((__force __sum16)addr->s6_addr16[idx] !=
62                             CSUM_MANGLED_0)
63                                 break;
64                 }
65                 if (idx == ARRAY_SIZE(addr->s6_addr16))
66                         return false;
67         }
68
69         sum = ~csum_fold(csum_add(csum_unfold((__force __sum16)addr->s6_addr16[idx]),
70                                   csum_unfold(npt->adjustment)));
71         if (sum == CSUM_MANGLED_0)
72                 sum = 0;
73         *(__force __sum16 *)&addr->s6_addr16[idx] = sum;
74
75         return true;
76 }
77
78 static unsigned int
79 ip6t_snpt_tg(struct sk_buff *skb, const struct xt_action_param *par)
80 {
81         const struct ip6t_npt_tginfo *npt = par->targinfo;
82
83         if (!ip6t_npt_map_pfx(npt, &ipv6_hdr(skb)->saddr)) {
84                 icmpv6_send(skb, ICMPV6_PARAMPROB, ICMPV6_HDR_FIELD,
85                             offsetof(struct ipv6hdr, saddr));
86                 return NF_DROP;
87         }
88         return XT_CONTINUE;
89 }
90
91 static unsigned int
92 ip6t_dnpt_tg(struct sk_buff *skb, const struct xt_action_param *par)
93 {
94         const struct ip6t_npt_tginfo *npt = par->targinfo;
95
96         if (!ip6t_npt_map_pfx(npt, &ipv6_hdr(skb)->daddr)) {
97                 icmpv6_send(skb, ICMPV6_PARAMPROB, ICMPV6_HDR_FIELD,
98                             offsetof(struct ipv6hdr, daddr));
99                 return NF_DROP;
100         }
101         return XT_CONTINUE;
102 }
103
104 static struct xt_target ip6t_npt_target_reg[] __read_mostly = {
105         {
106                 .name           = "SNPT",
107                 .target         = ip6t_snpt_tg,
108                 .targetsize     = sizeof(struct ip6t_npt_tginfo),
109                 .checkentry     = ip6t_npt_checkentry,
110                 .family         = NFPROTO_IPV6,
111                 .hooks          = (1 << NF_INET_LOCAL_IN) |
112                                   (1 << NF_INET_POST_ROUTING),
113                 .me             = THIS_MODULE,
114         },
115         {
116                 .name           = "DNPT",
117                 .target         = ip6t_dnpt_tg,
118                 .targetsize     = sizeof(struct ip6t_npt_tginfo),
119                 .checkentry     = ip6t_npt_checkentry,
120                 .family         = NFPROTO_IPV6,
121                 .hooks          = (1 << NF_INET_PRE_ROUTING) |
122                                   (1 << NF_INET_LOCAL_OUT),
123                 .me             = THIS_MODULE,
124         },
125 };
126
127 static int __init ip6t_npt_init(void)
128 {
129         return xt_register_targets(ip6t_npt_target_reg,
130                                    ARRAY_SIZE(ip6t_npt_target_reg));
131 }
132
133 static void __exit ip6t_npt_exit(void)
134 {
135         xt_unregister_targets(ip6t_npt_target_reg,
136                               ARRAY_SIZE(ip6t_npt_target_reg));
137 }
138
139 module_init(ip6t_npt_init);
140 module_exit(ip6t_npt_exit);
141
142 MODULE_LICENSE("GPL");
143 MODULE_DESCRIPTION("IPv6-to-IPv6 Network Prefix Translation (RFC 6296)");
144 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
145 MODULE_ALIAS("ip6t_SNPT");
146 MODULE_ALIAS("ip6t_DNPT");