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
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
|
/* IP tables module for matching IPsec policy
*
* Copyright (c) 2004,2005 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/kernel.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <net/xfrm.h>
#include <linux/netfilter.h>
#include <linux/netfilter/xt_policy.h>
#include <linux/netfilter/x_tables.h>
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_DESCRIPTION("Xtables: IPsec policy match");
MODULE_LICENSE("GPL");
static inline bool
xt_addr_cmp(const union nf_inet_addr *a1, const union nf_inet_addr *m,
const union nf_inet_addr *a2, unsigned short family)
{
switch (family) {
case NFPROTO_IPV4:
return ((a1->ip ^ a2->ip) & m->ip) == 0;
case NFPROTO_IPV6:
return ipv6_masked_addr_cmp(&a1->in6, &m->in6, &a2->in6) == 0;
}
return false;
}
static bool
match_xfrm_state(const struct xfrm_state *x, const struct xt_policy_elem *e,
unsigned short family)
{
#define MATCH_ADDR(x,y,z) (!e->match.x || \
(xt_addr_cmp(&e->x, &e->y, (const union nf_inet_addr *)(z), family) \
^ e->invert.x))
#define MATCH(x,y) (!e->match.x || ((e->x == (y)) ^ e->invert.x))
return MATCH_ADDR(saddr, smask, &x->props.saddr) &&
MATCH_ADDR(daddr, dmask, &x->id.daddr) &&
MATCH(proto, x->id.proto) &&
MATCH(mode, x->props.mode) &&
MATCH(spi, x->id.spi) &&
MATCH(reqid, x->props.reqid);
}
static int
match_policy_in(const struct sk_buff *skb, const struct xt_policy_info *info,
unsigned short family)
{
const struct xt_policy_elem *e;
const struct sec_path *sp = skb->sp;
int strict = info->flags & XT_POLICY_MATCH_STRICT;
int i, pos;
if (sp == NULL)
return -1;
if (strict && info->len != sp->len)
return 0;
for (i = sp->len - 1; i >= 0; i--) {
pos = strict ? i - sp->len + 1 : 0;
if (pos >= info->len)
return 0;
e = &info->pol[pos];
if (match_xfrm_state(sp->xvec[i], e, family)) {
if (!strict)
return 1;
} else if (strict)
return 0;
}
return strict ? 1 : 0;
}
static int
match_policy_out(const struct sk_buff *skb, const struct xt_policy_info *info,
unsigned short family)
{
const struct xt_policy_elem *e;
const struct dst_entry *dst = skb->dst;
int strict = info->flags & XT_POLICY_MATCH_STRICT;
int i, pos;
if (dst->xfrm == NULL)
return -1;
for (i = 0; dst && dst->xfrm; dst = dst->child, i++) {
pos = strict ? i : 0;
if (pos >= info->len)
return 0;
e = &info->pol[pos];
if (match_xfrm_state(dst->xfrm, e, family)) {
if (!strict)
return 1;
} else if (strict)
return 0;
}
return strict ? i == info->len : 0;
}
static bool
policy_mt(const struct sk_buff *skb, const struct xt_match_param *par)
{
const struct xt_policy_info *info = par->matchinfo;
int ret;
if (info->flags & XT_POLICY_MATCH_IN)
ret = match_policy_in(skb, info, par->match->family);
else
ret = match_policy_out(skb, info, par->match->family);
if (ret < 0)
ret = info->flags & XT_POLICY_MATCH_NONE ? true : false;
else if (info->flags & XT_POLICY_MATCH_NONE)
ret = false;
return ret;
}
static bool
policy_mt_check(const char *tablename, const void *ip_void,
const struct xt_match *match, void *matchinfo,
unsigned int hook_mask)
{
const struct xt_policy_info *info = matchinfo;
if (!(info->flags & (XT_POLICY_MATCH_IN|XT_POLICY_MATCH_OUT))) {
printk(KERN_ERR "xt_policy: neither incoming nor "
"outgoing policy selected\n");
return false;
}
if (hook_mask & (1 << NF_INET_PRE_ROUTING | 1 << NF_INET_LOCAL_IN)
&& info->flags & XT_POLICY_MATCH_OUT) {
printk(KERN_ERR "xt_policy: output policy not valid in "
"PRE_ROUTING and INPUT\n");
return false;
}
if (hook_mask & (1 << NF_INET_POST_ROUTING | 1 << NF_INET_LOCAL_OUT)
&& info->flags & XT_POLICY_MATCH_IN) {
printk(KERN_ERR "xt_policy: input policy not valid in "
"POST_ROUTING and OUTPUT\n");
return false;
}
if (info->len > XT_POLICY_MAX_ELEM) {
printk(KERN_ERR "xt_policy: too many policy elements\n");
return false;
}
return true;
}
static struct xt_match policy_mt_reg[] __read_mostly = {
{
.name = "policy",
.family = NFPROTO_IPV4,
.checkentry = policy_mt_check,
.match = policy_mt,
.matchsize = sizeof(struct xt_policy_info),
.me = THIS_MODULE,
},
{
.name = "policy",
.family = NFPROTO_IPV6,
.checkentry = policy_mt_check,
.match = policy_mt,
.matchsize = sizeof(struct xt_policy_info),
.me = THIS_MODULE,
},
};
static int __init policy_mt_init(void)
{
return xt_register_matches(policy_mt_reg, ARRAY_SIZE(policy_mt_reg));
}
static void __exit policy_mt_exit(void)
{
xt_unregister_matches(policy_mt_reg, ARRAY_SIZE(policy_mt_reg));
}
module_init(policy_mt_init);
module_exit(policy_mt_exit);
MODULE_ALIAS("ipt_policy");
MODULE_ALIAS("ip6t_policy");
|
