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
|
/* Kernel module to match AH 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/ip.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_ah.h>
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("IPv6 AH 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("ah 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_auth_hdr *ah, _ah;
const struct ip6t_ah *ahinfo = matchinfo;
unsigned int ptr;
unsigned int hdrlen = 0;
if (ipv6_find_hdr(skb, &ptr, NEXTHDR_AUTH) < 0)
return 0;
ah = skb_header_pointer(skb, ptr, sizeof(_ah), &_ah);
if (ah == NULL) {
*hotdrop = 1;
return 0;
}
hdrlen = (ah->hdrlen + 2) << 2;
DEBUGP("IPv6 AH LEN %u %u ", hdrlen, ah->hdrlen);
DEBUGP("RES %04X ", ah->reserved);
DEBUGP("SPI %u %08X\n", ntohl(ah->spi), ntohl(ah->spi));
DEBUGP("IPv6 AH spi %02X ",
(spi_match(ahinfo->spis[0], ahinfo->spis[1],
ntohl(ah->spi),
!!(ahinfo->invflags & IP6T_AH_INV_SPI))));
DEBUGP("len %02X %04X %02X ",
ahinfo->hdrlen, hdrlen,
(!ahinfo->hdrlen ||
(ahinfo->hdrlen == hdrlen) ^
!!(ahinfo->invflags & IP6T_AH_INV_LEN)));
DEBUGP("res %02X %04X %02X\n",
ahinfo->hdrres, ah->reserved,
!(ahinfo->hdrres && ah->reserved));
return (ah != NULL)
&&
(spi_match(ahinfo->spis[0], ahinfo->spis[1],
ntohl(ah->spi),
!!(ahinfo->invflags & IP6T_AH_INV_SPI)))
&&
(!ahinfo->hdrlen ||
(ahinfo->hdrlen == hdrlen) ^
!!(ahinfo->invflags & IP6T_AH_INV_LEN))
&&
!(ahinfo->hdrres && ah->reserved);
}
/* 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_ah *ahinfo = matchinfo;
if (matchinfosize != IP6T_ALIGN(sizeof(struct ip6t_ah))) {
DEBUGP("ip6t_ah: matchsize %u != %u\n",
matchinfosize, IP6T_ALIGN(sizeof(struct ip6t_ah)));
return 0;
}
if (ahinfo->invflags & ~IP6T_AH_INV_MASK) {
DEBUGP("ip6t_ah: unknown flags %X\n", ahinfo->invflags);
return 0;
}
return 1;
}
static struct ip6t_match ah_match = {
.name = "ah",
.match = &match,
.checkentry = &checkentry,
.me = THIS_MODULE,
};
static int __init init(void)
{
return ip6t_register_match(&ah_match);
}
static void __exit cleanup(void)
{
ip6t_unregister_match(&ah_match);
}
module_init(init);
module_exit(cleanup);
|
