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/* (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_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,
const void *protohdr,
u_int16_t datalen,
int *hotdrop)
{
struct ip_auth_hdr *ah = NULL;
const struct ip6t_ah *ahinfo = matchinfo;
unsigned int temp;
int len;
u8 nexthdr;
unsigned int ptr;
unsigned int hdrlen = 0;
/*DEBUGP("IPv6 AH entered\n");*/
/* if (opt->auth == 0) return 0;
* It does not filled on output */
/* 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;
DEBUGP("ipv6_ah header iteration \n");
/* Is there enough space for the next ext header? */
if (len < (int)sizeof(struct ipv6_opt_hdr))
return 0;
/* No more exthdr -> evaluate */
if (nexthdr == NEXTHDR_NONE) {
break;
}
/* ESP -> evaluate */
if (nexthdr == NEXTHDR_ESP) {
break;
}
hdr=(struct ipv6_opt_hdr *)skb->data+ptr;
/* Calculate the header length */
if (nexthdr == NEXTHDR_FRAGMENT) {
hdrlen = 8;
} else if (nexthdr == NEXTHDR_AUTH)
hdrlen = (hdr->hdrlen+2)<<2;
else
hdrlen = ipv6_optlen(hdr);
/* AH -> evaluate */
if (nexthdr == NEXTHDR_AUTH) {
temp |= MASK_AH;
break;
}
/* set the flag */
switch (nexthdr){
case NEXTHDR_HOP:
case NEXTHDR_ROUTING:
case NEXTHDR_FRAGMENT:
case NEXTHDR_AUTH:
case NEXTHDR_DEST:
break;
default:
DEBUGP("ipv6_ah match: unknown nextheader %u\n",nexthdr);
return 0;
break;
}
nexthdr = hdr->nexthdr;
len -= hdrlen;
ptr += hdrlen;
if ( ptr > skb->len ) {
DEBUGP("ipv6_ah: new pointer too large! \n");
break;
}
}
/* AH header not found */
if ( temp != MASK_AH ) return 0;
if (len < (int)sizeof(struct ip_auth_hdr)){
*hotdrop = 1;
return 0;
}
ah = (struct ip_auth_hdr *) (skb->data + ptr);
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);
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