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
195
196
197
198
199
200
201
202
|
/* 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/xt_policy.h>
#include <linux/netfilter/x_tables.h>
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_DESCRIPTION("Xtables IPsec policy matching module");
MODULE_LICENSE("GPL");
static inline int
xt_addr_cmp(const union xt_policy_addr *a1, const union xt_policy_addr *m,
const union xt_policy_addr *a2, unsigned short family)
{
switch (family) {
case AF_INET:
return !((a1->a4.s_addr ^ a2->a4.s_addr) & m->a4.s_addr);
case AF_INET6:
return !ipv6_masked_addr_cmp(&a1->a6, &m->a6, &a2->a6);
}
return 0;
}
static inline int
match_xfrm_state(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, z, family) \
^ e->invert.x))
#define MATCH(x,y) (!e->match.x || ((e->x == (y)) ^ e->invert.x))
return MATCH_ADDR(saddr, smask, (union xt_policy_addr *)&x->props.saddr) &&
MATCH_ADDR(daddr, dmask, (union xt_policy_addr *)&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;
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;
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 int match(const struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
const struct xt_match *match,
const void *matchinfo,
int offset,
unsigned int protoff,
int *hotdrop)
{
const struct xt_policy_info *info = matchinfo;
int ret;
if (info->flags & XT_POLICY_MATCH_IN)
ret = match_policy_in(skb, info, match->family);
else
ret = match_policy_out(skb, info, match->family);
if (ret < 0)
ret = info->flags & XT_POLICY_MATCH_NONE ? 1 : 0;
else if (info->flags & XT_POLICY_MATCH_NONE)
ret = 0;
return ret;
}
static int checkentry(const char *tablename, const void *ip_void,
const struct xt_match *match,
void *matchinfo, unsigned int hook_mask)
{
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 0;
}
/* hook values are equal for IPv4 and IPv6 */
if (hook_mask & (1 << NF_IP_PRE_ROUTING | 1 << NF_IP_LOCAL_IN)
&& info->flags & XT_POLICY_MATCH_OUT) {
printk(KERN_ERR "xt_policy: output policy not valid in "
"PRE_ROUTING and INPUT\n");
return 0;
}
if (hook_mask & (1 << NF_IP_POST_ROUTING | 1 << NF_IP_LOCAL_OUT)
&& info->flags & XT_POLICY_MATCH_IN) {
printk(KERN_ERR "xt_policy: input policy not valid in "
"POST_ROUTING and OUTPUT\n");
return 0;
}
if (info->len > XT_POLICY_MAX_ELEM) {
printk(KERN_ERR "xt_policy: too many policy elements\n");
return 0;
}
return 1;
}
static struct xt_match xt_policy_match[] = {
{
.name = "policy",
.family = AF_INET,
.checkentry = checkentry,
.match = match,
.matchsize = sizeof(struct xt_policy_info),
.family = AF_INET,
.me = THIS_MODULE,
},
{
.name = "policy",
.family = AF_INET6,
.checkentry = checkentry,
.match = match,
.matchsize = sizeof(struct xt_policy_info),
.family = AF_INET6,
.me = THIS_MODULE,
},
};
static int __init init(void)
{
return xt_register_matches(xt_policy_match,
ARRAY_SIZE(xt_policy_match));
}
static void __exit fini(void)
{
xt_unregister_matches(xt_policy_match, ARRAY_SIZE(xt_policy_match));
}
module_init(init);
module_exit(fini);
MODULE_ALIAS("ipt_policy");
MODULE_ALIAS("ip6t_policy");
|
