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
|
/* Kernel module to match ESP parameters. */
/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
*
* 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 <linux/types.h>
#include <net/checksum.h>
#include <net/ipv6.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter_ipv6/ip6t_esp.h>
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("IPv6 ESP match");
MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif
/* Returns 1 if the spi is matched by the range, 0 otherwise */
static inline int
spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, int invert)
{
int r=0;
DEBUGP("esp spi_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ',
min,spi,max);
r=(spi >= min && spi <= max) ^ invert;
DEBUGP(" result %s\n",r? "PASS\n" : "FAILED\n");
return r;
}
static int
match(const struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
const void *matchinfo,
int offset,
unsigned int protoff,
int *hotdrop)
{
struct ip_esp_hdr _esp, *eh = NULL;
const struct ip6t_esp *espinfo = matchinfo;
unsigned int temp;
int len;
u8 nexthdr;
unsigned int ptr;
/* Make sure this isn't an evil packet */
/*DEBUGP("ipv6_esp entered \n");*/
/* type of the 1st exthdr */
nexthdr = skb->nh.ipv6h->nexthdr;
/* pointer to the 1st exthdr */
ptr = sizeof(struct ipv6hdr);
/* available length */
len = skb->len - ptr;
temp = 0;
while (ip6t_ext_hdr(nexthdr)) {
struct ipv6_opt_hdr _hdr, *hp;
int hdrlen;
DEBUGP("ipv6_esp header iteration \n");
/* Is there enough space for the next ext header? */
if (len < sizeof(struct ipv6_opt_hdr))
return 0;
/* No more exthdr -> evaluate */
if (nexthdr == NEXTHDR_NONE)
break;
/* ESP -> evaluate */
if (nexthdr == NEXTHDR_ESP) {
temp |= MASK_ESP;
break;
}
hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr);
BUG_ON(hp == NULL);
/* Calculate the header length */
if (nexthdr == NEXTHDR_FRAGMENT)
hdrlen = 8;
else if (nexthdr == NEXTHDR_AUTH)
hdrlen = (hp->hdrlen+2)<<2;
else
hdrlen = ipv6_optlen(hp);
/* set the flag */
switch (nexthdr) {
case NEXTHDR_HOP:
case NEXTHDR_ROUTING:
case NEXTHDR_FRAGMENT:
case NEXTHDR_AUTH:
case NEXTHDR_DEST:
break;
default:
DEBUGP("ipv6_esp match: unknown nextheader %u\n",nexthdr);
return 0;
}
nexthdr = hp->nexthdr;
len -= hdrlen;
ptr += hdrlen;
if (ptr > skb->len) {
DEBUGP("ipv6_esp: new pointer too large! \n");
break;
}
}
/* ESP header not found */
if (temp != MASK_ESP)
return 0;
if (len < sizeof(struct ip_esp_hdr)) {
*hotdrop = 1;
return 0;
}
eh = skb_header_pointer(skb, ptr, sizeof(_esp), &_esp);
BUG_ON(eh == NULL);
DEBUGP("IPv6 ESP SPI %u %08X\n", ntohl(eh->spi), ntohl(eh->spi));
return (eh != NULL)
&& spi_match(espinfo->spis[0], espinfo->spis[1],
ntohl(eh->spi),
!!(espinfo->invflags & IP6T_ESP_INV_SPI));
}
/* Called when user tries to insert an entry of this type. */
static int
checkentry(const char *tablename,
const struct ip6t_ip6 *ip,
void *matchinfo,
unsigned int matchinfosize,
unsigned int hook_mask)
{
const struct ip6t_esp *espinfo = matchinfo;
if (matchinfosize != IP6T_ALIGN(sizeof(struct ip6t_esp))) {
DEBUGP("ip6t_esp: matchsize %u != %u\n",
matchinfosize, IP6T_ALIGN(sizeof(struct ip6t_esp)));
return 0;
}
if (espinfo->invflags & ~IP6T_ESP_INV_MASK) {
DEBUGP("ip6t_esp: unknown flags %X\n",
espinfo->invflags);
return 0;
}
return 1;
}
static struct ip6t_match esp_match = {
.name = "esp",
.match = &match,
.checkentry = &checkentry,
.me = THIS_MODULE,
};
static int __init init(void)
{
return ip6t_register_match(&esp_match);
}
static void __exit cleanup(void)
{
ip6t_unregister_match(&esp_match);
}
module_init(init);
module_exit(cleanup);
|
