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 #include <linux/types.h>
15 #include <linux/module.h>
16 #include <net/ip.h>
17 #include <linux/ipv6.h>
18 #include <net/ipv6.h>
19 #include <net/mip6.h>
20
21 #include <linux/netfilter/x_tables.h>
22 #include <linux/netfilter_ipv6/ip6t_mh.h>
23
24 MODULE_DESCRIPTION("Xtables: IPv6 Mobility Header match");
25 MODULE_LICENSE("GPL");
26
27 #ifdef DEBUG_IP_FIREWALL_USER
28 #define duprintf(format, args...) printk(format , ## args)
29 #else
30 #define duprintf(format, args...)
31 #endif
32
33 /* Returns 1 if the type is matched by the range, 0 otherwise */
34 static inline bool
type_match(u_int8_t min,u_int8_t max,u_int8_t type,bool invert)35 type_match(u_int8_t min, u_int8_t max, u_int8_t type, bool invert)
36 {
37 return (type >= min && type <= max) ^ invert;
38 }
39
mh_mt6(const struct sk_buff * skb,const struct xt_match_param * par)40 static bool mh_mt6(const struct sk_buff *skb, const struct xt_match_param *par)
41 {
42 struct ip6_mh _mh;
43 const struct ip6_mh *mh;
44 const struct ip6t_mh *mhinfo = par->matchinfo;
45
46 /* Must not be a fragment. */
47 if (par->fragoff != 0)
48 return false;
49
50 mh = skb_header_pointer(skb, par->thoff, sizeof(_mh), &_mh);
51 if (mh == NULL) {
52 /* We've been asked to examine this packet, and we
53 can't. Hence, no choice but to drop. */
54 duprintf("Dropping evil MH tinygram.\n");
55 *par->hotdrop = true;
56 return false;
57 }
58
59 if (mh->ip6mh_proto != IPPROTO_NONE) {
60 duprintf("Dropping invalid MH Payload Proto: %u\n",
61 mh->ip6mh_proto);
62 *par->hotdrop = true;
63 return false;
64 }
65
66 return type_match(mhinfo->types[0], mhinfo->types[1], mh->ip6mh_type,
67 !!(mhinfo->invflags & IP6T_MH_INV_TYPE));
68 }
69
mh_mt6_check(const struct xt_mtchk_param * par)70 static bool mh_mt6_check(const struct xt_mtchk_param *par)
71 {
72 const struct ip6t_mh *mhinfo = par->matchinfo;
73
74 /* Must specify no unknown invflags */
75 return !(mhinfo->invflags & ~IP6T_MH_INV_MASK);
76 }
77
78 static struct xt_match mh_mt6_reg __read_mostly = {
79 .name = "mh",
80 .family = NFPROTO_IPV6,
81 .checkentry = mh_mt6_check,
82 .match = mh_mt6,
83 .matchsize = sizeof(struct ip6t_mh),
84 .proto = IPPROTO_MH,
85 .me = THIS_MODULE,
86 };
87
mh_mt6_init(void)88 static int __init mh_mt6_init(void)
89 {
90 return xt_register_match(&mh_mt6_reg);
91 }
92
mh_mt6_exit(void)93 static void __exit mh_mt6_exit(void)
94 {
95 xt_unregister_match(&mh_mt6_reg);
96 }
97
98 module_init(mh_mt6_init);
99 module_exit(mh_mt6_exit);
100