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/* 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/x_tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter_ipv6/ip6t_ah.h>
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Xtables: IPv6 IPsec-AH match");
MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
/* Returns 1 if the spi is matched by the range, 0 otherwise */
static inline bool
spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert)
{
bool r;
pr_debug("ah spi_match:%c 0x%x <= 0x%x <= 0x%x",
invert ? '!' : ' ', min, spi, max);
r = (spi >= min && spi <= max) ^ invert;
pr_debug(" result %s\n", r ? "PASS" : "FAILED");
return r;
}
static bool
ah_mt6(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, bool *hotdrop)
{
struct ip_auth_hdr _ah;
const struct ip_auth_hdr *ah;
const struct ip6t_ah *ahinfo = matchinfo;
unsigned int ptr;
unsigned int hdrlen = 0;
int err;
err = ipv6_find_hdr(skb, &ptr, NEXTHDR_AUTH, NULL);
if (err < 0) {
if (err != -ENOENT)
*hotdrop = true;
return false;
}
ah = skb_header_pointer(skb, ptr, sizeof(_ah), &_ah);
if (ah == NULL) {
*hotdrop = true;
return false;
}
hdrlen = (ah->hdrlen + 2) << 2;
pr_debug("IPv6 AH LEN %u %u ", hdrlen, ah->hdrlen);
pr_debug("RES %04X ", ah->reserved);
pr_debug("SPI %u %08X\n", ntohl(ah->spi), ntohl(ah->spi));
pr_debug("IPv6 AH spi %02X ",
spi_match(ahinfo->spis[0], ahinfo->spis[1],
ntohl(ah->spi),
!!(ahinfo->invflags & IP6T_AH_INV_SPI)));
pr_debug("len %02X %04X %02X ",
ahinfo->hdrlen, hdrlen,
(!ahinfo->hdrlen ||
(ahinfo->hdrlen == hdrlen) ^
!!(ahinfo->invflags & IP6T_AH_INV_LEN)));
pr_debug("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 bool
ah_mt6_check(const char *tablename, const void *entry,
const struct xt_match *match, void *matchinfo,
unsigned int hook_mask)
{
const struct ip6t_ah *ahinfo = matchinfo;
if (ahinfo->invflags & ~IP6T_AH_INV_MASK) {
pr_debug("ip6t_ah: unknown flags %X\n", ahinfo->invflags);
return false;
}
return true;
}
static struct xt_match ah_mt6_reg __read_mostly = {
.name = "ah",
.family = AF_INET6,
.match = ah_mt6,
.matchsize = sizeof(struct ip6t_ah),
.checkentry = ah_mt6_check,
.me = THIS_MODULE,
};
static int __init ah_mt6_init(void)
{
return xt_register_match(&ah_mt6_reg);
}
static void __exit ah_mt6_exit(void)
{
xt_unregister_match(&ah_mt6_reg);
}
module_init(ah_mt6_init);
module_exit(ah_mt6_exit);
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