1/*
2 * Copyright (C)2006 USAGI/WIDE Project
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 *
8 * Author:
9 *	Masahide NAKAMURA @USAGI <masahide.nakamura.cz@hitachi.com>
10 *
11 * Based on net/netfilter/xt_tcpudp.c
12 *
13 */
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15#include <linux/types.h>
16#include <linux/module.h>
17#include <net/ip.h>
18#include <linux/ipv6.h>
19#include <net/ipv6.h>
20#include <net/mip6.h>
21
22#include <linux/netfilter/x_tables.h>
23#include <linux/netfilter_ipv6/ip6t_mh.h>
24
25MODULE_DESCRIPTION("Xtables: IPv6 Mobility Header match");
26MODULE_LICENSE("GPL");
27
28/* Returns 1 if the type is matched by the range, 0 otherwise */
29static inline bool
30type_match(u_int8_t min, u_int8_t max, u_int8_t type, bool invert)
31{
32	return (type >= min && type <= max) ^ invert;
33}
34
35static bool mh_mt6(const struct sk_buff *skb, struct xt_action_param *par)
36{
37	struct ip6_mh _mh;
38	const struct ip6_mh *mh;
39	const struct ip6t_mh *mhinfo = par->matchinfo;
40
41	/* Must not be a fragment. */
42	if (par->fragoff != 0)
43		return false;
44
45	mh = skb_header_pointer(skb, par->thoff, sizeof(_mh), &_mh);
46	if (mh == NULL) {
47		/* We've been asked to examine this packet, and we
48		   can't.  Hence, no choice but to drop. */
49		pr_debug("Dropping evil MH tinygram.\n");
50		par->hotdrop = true;
51		return false;
52	}
53
54	if (mh->ip6mh_proto != IPPROTO_NONE) {
55		pr_debug("Dropping invalid MH Payload Proto: %u\n",
56			 mh->ip6mh_proto);
57		par->hotdrop = true;
58		return false;
59	}
60
61	return type_match(mhinfo->types[0], mhinfo->types[1], mh->ip6mh_type,
62			  !!(mhinfo->invflags & IP6T_MH_INV_TYPE));
63}
64
65static int mh_mt6_check(const struct xt_mtchk_param *par)
66{
67	const struct ip6t_mh *mhinfo = par->matchinfo;
68
69	/* Must specify no unknown invflags */
70	return (mhinfo->invflags & ~IP6T_MH_INV_MASK) ? -EINVAL : 0;
71}
72
73static struct xt_match mh_mt6_reg __read_mostly = {
74	.name		= "mh",
75	.family		= NFPROTO_IPV6,
76	.checkentry	= mh_mt6_check,
77	.match		= mh_mt6,
78	.matchsize	= sizeof(struct ip6t_mh),
79	.proto		= IPPROTO_MH,
80	.me		= THIS_MODULE,
81};
82
83static int __init mh_mt6_init(void)
84{
85	return xt_register_match(&mh_mt6_reg);
86}
87
88static void __exit mh_mt6_exit(void)
89{
90	xt_unregister_match(&mh_mt6_reg);
91}
92
93module_init(mh_mt6_init);
94module_exit(mh_mt6_exit);
95