ip6t_mh.c
/*
* Copyright (C)2006 USAGI/WIDE Project
*
* 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.
*
* Author:
* Masahide NAKAMURA @USAGI <masahide.nakamura.cz@hitachi.com>
*
* Based on net/netfilter/xt_tcpudp.c
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/types.h>
#include <linux/module.h>
#include <net/ip.h>
#include <linux/ipv6.h>
#include <net/ipv6.h>
#include <net/mip6.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv6/ip6t_mh.h>
MODULE_DESCRIPTION("Xtables: IPv6 Mobility Header match");
MODULE_LICENSE("GPL");
/* Returns 1 if the type is matched by the range, 0 otherwise */
static inline bool
type_match(u_int8_t min, u_int8_t max, u_int8_t type, bool invert)
{
return (type >= min && type <= max) ^ invert;
}
static bool mh_mt6(const struct sk_buff *skb, struct xt_action_param *par)
{
struct ip6_mh _mh;
const struct ip6_mh *mh;
const struct ip6t_mh *mhinfo = par->matchinfo;
/* Must not be a fragment. */
if (par->fragoff != 0)
return false;
mh = skb_header_pointer(skb, par->thoff, sizeof(_mh), &_mh);
if (mh == NULL) {
/* We've been asked to examine this packet, and we
can't. Hence, no choice but to drop. */
pr_debug("Dropping evil MH tinygram.\n");
par->hotdrop = true;
return false;
}
if (mh->ip6mh_proto != IPPROTO_NONE) {
pr_debug("Dropping invalid MH Payload Proto: %u\n",
mh->ip6mh_proto);
par->hotdrop = true;
return false;
}
return type_match(mhinfo->types[0], mhinfo->types[1], mh->ip6mh_type,
!!(mhinfo->invflags & IP6T_MH_INV_TYPE));
}
static int mh_mt6_check(const struct xt_mtchk_param *par)
{
const struct ip6t_mh *mhinfo = par->matchinfo;
/* Must specify no unknown invflags */
return (mhinfo->invflags & ~IP6T_MH_INV_MASK) ? -EINVAL : 0;
}
static struct xt_match mh_mt6_reg __read_mostly = {
.name = "mh",
.family = NFPROTO_IPV6,
.checkentry = mh_mt6_check,
.match = mh_mt6,
.matchsize = sizeof(struct ip6t_mh),
.proto = IPPROTO_MH,
.me = THIS_MODULE,
};
static int __init mh_mt6_init(void)
{
return xt_register_match(&mh_mt6_reg);
}
static void __exit mh_mt6_exit(void)
{
xt_unregister_match(&mh_mt6_reg);
}
module_init(mh_mt6_init);
module_exit(mh_mt6_exit);