1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
|
/*
* Copyright (c) 2011, 2012 Patrick McHardy <kaber@trash.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ipv6.h>
#include <net/ipv6.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv6.h>
#include <linux/netfilter_ipv6/ip6t_NPT.h>
#include <linux/netfilter/x_tables.h>
static int ip6t_npt_checkentry(const struct xt_tgchk_param *par)
{
struct ip6t_npt_tginfo *npt = par->targinfo;
__wsum src_sum = 0, dst_sum = 0;
struct in6_addr pfx;
unsigned int i;
if (npt->src_pfx_len > 64 || npt->dst_pfx_len > 64)
return -EINVAL;
/* Ensure that LSB of prefix is zero */
ipv6_addr_prefix(&pfx, &npt->src_pfx.in6, npt->src_pfx_len);
if (!ipv6_addr_equal(&pfx, &npt->src_pfx.in6))
return -EINVAL;
ipv6_addr_prefix(&pfx, &npt->dst_pfx.in6, npt->dst_pfx_len);
if (!ipv6_addr_equal(&pfx, &npt->dst_pfx.in6))
return -EINVAL;
for (i = 0; i < ARRAY_SIZE(npt->src_pfx.in6.s6_addr16); i++) {
src_sum = csum_add(src_sum,
(__force __wsum)npt->src_pfx.in6.s6_addr16[i]);
dst_sum = csum_add(dst_sum,
(__force __wsum)npt->dst_pfx.in6.s6_addr16[i]);
}
npt->adjustment = ~csum_fold(csum_sub(src_sum, dst_sum));
return 0;
}
static bool ip6t_npt_map_pfx(const struct ip6t_npt_tginfo *npt,
struct in6_addr *addr)
{
unsigned int pfx_len;
unsigned int i, idx;
__be32 mask;
__sum16 sum;
pfx_len = max(npt->src_pfx_len, npt->dst_pfx_len);
for (i = 0; i < pfx_len; i += 32) {
if (pfx_len - i >= 32)
mask = 0;
else
mask = htonl(~((1 << (pfx_len - i)) - 1));
idx = i / 32;
addr->s6_addr32[idx] &= mask;
addr->s6_addr32[idx] |= ~mask & npt->dst_pfx.in6.s6_addr32[idx];
}
if (pfx_len <= 48)
idx = 3;
else {
for (idx = 4; idx < ARRAY_SIZE(addr->s6_addr16); idx++) {
if ((__force __sum16)addr->s6_addr16[idx] !=
CSUM_MANGLED_0)
break;
}
if (idx == ARRAY_SIZE(addr->s6_addr16))
return false;
}
sum = ~csum_fold(csum_add(csum_unfold((__force __sum16)addr->s6_addr16[idx]),
csum_unfold(npt->adjustment)));
if (sum == CSUM_MANGLED_0)
sum = 0;
*(__force __sum16 *)&addr->s6_addr16[idx] = sum;
return true;
}
static unsigned int
ip6t_snpt_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
const struct ip6t_npt_tginfo *npt = par->targinfo;
if (!ip6t_npt_map_pfx(npt, &ipv6_hdr(skb)->saddr)) {
icmpv6_send(skb, ICMPV6_PARAMPROB, ICMPV6_HDR_FIELD,
offsetof(struct ipv6hdr, saddr));
return NF_DROP;
}
return XT_CONTINUE;
}
static unsigned int
ip6t_dnpt_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
const struct ip6t_npt_tginfo *npt = par->targinfo;
if (!ip6t_npt_map_pfx(npt, &ipv6_hdr(skb)->daddr)) {
icmpv6_send(skb, ICMPV6_PARAMPROB, ICMPV6_HDR_FIELD,
offsetof(struct ipv6hdr, daddr));
return NF_DROP;
}
return XT_CONTINUE;
}
static struct xt_target ip6t_npt_target_reg[] __read_mostly = {
{
.name = "SNPT",
.table = "mangle",
.target = ip6t_snpt_tg,
.targetsize = sizeof(struct ip6t_npt_tginfo),
.checkentry = ip6t_npt_checkentry,
.family = NFPROTO_IPV6,
.hooks = (1 << NF_INET_LOCAL_IN) |
(1 << NF_INET_POST_ROUTING),
.me = THIS_MODULE,
},
{
.name = "DNPT",
.table = "mangle",
.target = ip6t_dnpt_tg,
.targetsize = sizeof(struct ip6t_npt_tginfo),
.checkentry = ip6t_npt_checkentry,
.family = NFPROTO_IPV6,
.hooks = (1 << NF_INET_PRE_ROUTING) |
(1 << NF_INET_LOCAL_OUT),
.me = THIS_MODULE,
},
};
static int __init ip6t_npt_init(void)
{
return xt_register_targets(ip6t_npt_target_reg,
ARRAY_SIZE(ip6t_npt_target_reg));
}
static void __exit ip6t_npt_exit(void)
{
xt_unregister_targets(ip6t_npt_target_reg,
ARRAY_SIZE(ip6t_npt_target_reg));
}
module_init(ip6t_npt_init);
module_exit(ip6t_npt_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("IPv6-to-IPv6 Network Prefix Translation (RFC 6296)");
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_ALIAS("ip6t_SNPT");
MODULE_ALIAS("ip6t_DNPT");
|
