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>
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>
17 static __sum16
csum16_complement(__sum16 a
)
19 return (__force __sum16
)(0xffff - (__force u16
)a
);
22 static __sum16
csum16_add(__sum16 a
, __sum16 b
)
26 sum
= (__force u16
)a
+ (__force u16
)b
;
27 sum
+= (__force u16
)a
< (__force u16
)b
;
28 return (__force __sum16
)sum
;
31 static __sum16
csum16_sub(__sum16 a
, __sum16 b
)
33 return csum16_add(a
, csum16_complement(b
));
36 static int ip6t_npt_checkentry(const struct xt_tgchk_param
*par
)
38 struct ip6t_npt_tginfo
*npt
= par
->targinfo
;
39 __sum16 src_sum
= 0, dst_sum
= 0;
42 if (npt
->src_pfx_len
> 64 || npt
->dst_pfx_len
> 64)
45 for (i
= 0; i
< ARRAY_SIZE(npt
->src_pfx
.in6
.s6_addr16
); i
++) {
46 src_sum
= csum16_add(src_sum
,
47 (__force __sum16
)npt
->src_pfx
.in6
.s6_addr16
[i
]);
48 dst_sum
= csum16_add(dst_sum
,
49 (__force __sum16
)npt
->dst_pfx
.in6
.s6_addr16
[i
]);
52 npt
->adjustment
= csum16_sub(src_sum
, dst_sum
);
56 static bool ip6t_npt_map_pfx(const struct ip6t_npt_tginfo
*npt
,
57 struct in6_addr
*addr
)
64 pfx_len
= max(npt
->src_pfx_len
, npt
->dst_pfx_len
);
65 for (i
= 0; i
< pfx_len
; i
+= 32) {
66 if (pfx_len
- i
>= 32)
69 mask
= htonl(~((1 << (pfx_len
- i
)) - 1));
72 addr
->s6_addr32
[idx
] &= mask
;
73 addr
->s6_addr32
[idx
] |= npt
->dst_pfx
.in6
.s6_addr32
[idx
];
79 for (idx
= 4; idx
< ARRAY_SIZE(addr
->s6_addr16
); idx
++) {
80 if ((__force __sum16
)addr
->s6_addr16
[idx
] !=
84 if (idx
== ARRAY_SIZE(addr
->s6_addr16
))
88 sum
= csum16_add((__force __sum16
)addr
->s6_addr16
[idx
],
90 if (sum
== CSUM_MANGLED_0
)
92 *(__force __sum16
*)&addr
->s6_addr16
[idx
] = sum
;
98 ip6t_snpt_tg(struct sk_buff
*skb
, const struct xt_action_param
*par
)
100 const struct ip6t_npt_tginfo
*npt
= par
->targinfo
;
102 if (!ip6t_npt_map_pfx(npt
, &ipv6_hdr(skb
)->saddr
)) {
103 icmpv6_send(skb
, ICMPV6_PARAMPROB
, ICMPV6_HDR_FIELD
,
104 offsetof(struct ipv6hdr
, saddr
));
111 ip6t_dnpt_tg(struct sk_buff
*skb
, const struct xt_action_param
*par
)
113 const struct ip6t_npt_tginfo
*npt
= par
->targinfo
;
115 if (!ip6t_npt_map_pfx(npt
, &ipv6_hdr(skb
)->daddr
)) {
116 icmpv6_send(skb
, ICMPV6_PARAMPROB
, ICMPV6_HDR_FIELD
,
117 offsetof(struct ipv6hdr
, daddr
));
123 static struct xt_target ip6t_npt_target_reg
[] __read_mostly
= {
126 .target
= ip6t_snpt_tg
,
127 .targetsize
= sizeof(struct ip6t_npt_tginfo
),
128 .checkentry
= ip6t_npt_checkentry
,
129 .family
= NFPROTO_IPV6
,
130 .hooks
= (1 << NF_INET_LOCAL_IN
) |
131 (1 << NF_INET_POST_ROUTING
),
136 .target
= ip6t_dnpt_tg
,
137 .targetsize
= sizeof(struct ip6t_npt_tginfo
),
138 .checkentry
= ip6t_npt_checkentry
,
139 .family
= NFPROTO_IPV6
,
140 .hooks
= (1 << NF_INET_PRE_ROUTING
) |
141 (1 << NF_INET_LOCAL_OUT
),
146 static int __init
ip6t_npt_init(void)
148 return xt_register_targets(ip6t_npt_target_reg
,
149 ARRAY_SIZE(ip6t_npt_target_reg
));
152 static void __exit
ip6t_npt_exit(void)
154 xt_unregister_targets(ip6t_npt_target_reg
,
155 ARRAY_SIZE(ip6t_npt_target_reg
));
158 module_init(ip6t_npt_init
);
159 module_exit(ip6t_npt_exit
);
161 MODULE_LICENSE("GPL");
162 MODULE_DESCRIPTION("IPv6-to-IPv6 Network Prefix Translation (RFC 6296)");
163 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
164 MODULE_ALIAS("ip6t_SNPT");
165 MODULE_ALIAS("ip6t_DNPT");