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/* 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/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_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 struct xt_match *match,
const void *matchinfo,
int offset,
unsigned int protoff,
int *hotdrop)
{
struct ip_esp_hdr _esp, *eh;
const struct ip6t_esp *espinfo = matchinfo;
unsigned int ptr;
/* Make sure this isn't an evil packet */
/*DEBUGP("ipv6_esp entered \n");*/
if (ipv6_find_hdr(skb, &ptr, NEXTHDR_ESP, NULL) < 0)
return 0;
eh = skb_header_pointer(skb, ptr, sizeof(_esp), &_esp);
if (eh == NULL) {
*hotdrop = 1;
return 0;
}
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 void *ip,
const struct xt_match *match,
void *matchinfo,
unsigned int matchinfosize,
unsigned int hook_mask)
{
const struct ip6t_esp *espinfo = matchinfo;
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,
.matchsize = sizeof(struct ip6t_esp),
.checkentry = checkentry,
.me = THIS_MODULE,
};
static int __init ip6t_esp_init(void)
{
return ip6t_register_match(&esp_match);
}
static void __exit ip6t_esp_fini(void)
{
ip6t_unregister_match(&esp_match);
}
module_init(ip6t_esp_init);
module_exit(ip6t_esp_fini);
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