121 lines
2.9 KiB
C
121 lines
2.9 KiB
C
/* Kernel module to match ESP parameters. */
|
|
|
|
/* (C) 1999-2000 Yon Uriarte <yon@astaro.de>
|
|
*
|
|
* 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/netfilter_ipv4/ipt_esp.h>
|
|
#include <linux/netfilter_ipv4/ip_tables.h>
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>");
|
|
MODULE_DESCRIPTION("iptables ESP SPI match module");
|
|
|
|
#ifdef DEBUG_CONNTRACK
|
|
#define duprintf(format, args...) printk(format , ## args)
|
|
#else
|
|
#define duprintf(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;
|
|
duprintf("esp spi_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ',
|
|
min,spi,max);
|
|
r=(spi >= min && spi <= max) ^ invert;
|
|
duprintf(" result %s\n",r? "PASS" : "FAILED");
|
|
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;
|
|
const struct ipt_esp *espinfo = matchinfo;
|
|
|
|
/* Must not be a fragment. */
|
|
if (offset)
|
|
return 0;
|
|
|
|
eh = skb_header_pointer(skb, protoff,
|
|
sizeof(_esp), &_esp);
|
|
if (eh == NULL) {
|
|
/* We've been asked to examine this packet, and we
|
|
* can't. Hence, no choice but to drop.
|
|
*/
|
|
duprintf("Dropping evil ESP tinygram.\n");
|
|
*hotdrop = 1;
|
|
return 0;
|
|
}
|
|
|
|
return spi_match(espinfo->spis[0], espinfo->spis[1],
|
|
ntohl(eh->spi),
|
|
!!(espinfo->invflags & IPT_ESP_INV_SPI));
|
|
}
|
|
|
|
/* Called when user tries to insert an entry of this type. */
|
|
static int
|
|
checkentry(const char *tablename,
|
|
const void *ip_void,
|
|
void *matchinfo,
|
|
unsigned int matchinfosize,
|
|
unsigned int hook_mask)
|
|
{
|
|
const struct ipt_esp *espinfo = matchinfo;
|
|
const struct ipt_ip *ip = ip_void;
|
|
|
|
/* Must specify proto == ESP, and no unknown invflags */
|
|
if (ip->proto != IPPROTO_ESP || (ip->invflags & IPT_INV_PROTO)) {
|
|
duprintf("ipt_esp: Protocol %u != %u\n", ip->proto,
|
|
IPPROTO_ESP);
|
|
return 0;
|
|
}
|
|
if (matchinfosize != IPT_ALIGN(sizeof(struct ipt_esp))) {
|
|
duprintf("ipt_esp: matchsize %u != %u\n",
|
|
matchinfosize, IPT_ALIGN(sizeof(struct ipt_esp)));
|
|
return 0;
|
|
}
|
|
if (espinfo->invflags & ~IPT_ESP_INV_MASK) {
|
|
duprintf("ipt_esp: unknown flags %X\n",
|
|
espinfo->invflags);
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
static struct ipt_match esp_match = {
|
|
.name = "esp",
|
|
.match = &match,
|
|
.checkentry = &checkentry,
|
|
.me = THIS_MODULE,
|
|
};
|
|
|
|
static int __init init(void)
|
|
{
|
|
return ipt_register_match(&esp_match);
|
|
}
|
|
|
|
static void __exit cleanup(void)
|
|
{
|
|
ipt_unregister_match(&esp_match);
|
|
}
|
|
|
|
module_init(init);
|
|
module_exit(cleanup);
|