1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C)2006 USAGI/WIDE Project
4 *
5 * Author:
6 * Masahide NAKAMURA @USAGI <masahide.nakamura.cz@hitachi.com>
7 *
8 * Based on net/netfilter/xt_tcpudp.c
9 */
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11#include <linux/types.h>
12#include <linux/module.h>
13#include <net/ip.h>
14#include <linux/ipv6.h>
15#include <net/ipv6.h>
16#include <net/mip6.h>
17
18#include <linux/netfilter/x_tables.h>
19#include <linux/netfilter_ipv6/ip6t_mh.h>
20
21MODULE_DESCRIPTION("Xtables: IPv6 Mobility Header match");
22MODULE_LICENSE("GPL");
23
24/* Returns 1 if the type is matched by the range, 0 otherwise */
25static inline bool
26type_match(u_int8_t min, u_int8_t max, u_int8_t type, bool invert)
27{
28 return (type >= min && type <= max) ^ invert;
29}
30
31static bool mh_mt6(const struct sk_buff *skb, struct xt_action_param *par)
32{
33 struct ip6_mh _mh;
34 const struct ip6_mh *mh;
35 const struct ip6t_mh *mhinfo = par->matchinfo;
36
37 /* Must not be a fragment. */
38 if (par->fragoff != 0)
39 return false;
40
41 mh = skb_header_pointer(skb, offset: par->thoff, len: sizeof(_mh), buffer: &_mh);
42 if (mh == NULL) {
43 /* We've been asked to examine this packet, and we
44 can't. Hence, no choice but to drop. */
45 pr_debug("Dropping evil MH tinygram.\n");
46 par->hotdrop = true;
47 return false;
48 }
49
50 if (mh->ip6mh_proto != IPPROTO_NONE) {
51 pr_debug("Dropping invalid MH Payload Proto: %u\n",
52 mh->ip6mh_proto);
53 par->hotdrop = true;
54 return false;
55 }
56
57 return type_match(min: mhinfo->types[0], max: mhinfo->types[1], type: mh->ip6mh_type,
58 invert: !!(mhinfo->invflags & IP6T_MH_INV_TYPE));
59}
60
61static int mh_mt6_check(const struct xt_mtchk_param *par)
62{
63 const struct ip6t_mh *mhinfo = par->matchinfo;
64
65 /* Must specify no unknown invflags */
66 return (mhinfo->invflags & ~IP6T_MH_INV_MASK) ? -EINVAL : 0;
67}
68
69static struct xt_match mh_mt6_reg __read_mostly = {
70 .name = "mh",
71 .family = NFPROTO_IPV6,
72 .checkentry = mh_mt6_check,
73 .match = mh_mt6,
74 .matchsize = sizeof(struct ip6t_mh),
75 .proto = IPPROTO_MH,
76 .me = THIS_MODULE,
77};
78
79static int __init mh_mt6_init(void)
80{
81 return xt_register_match(target: &mh_mt6_reg);
82}
83
84static void __exit mh_mt6_exit(void)
85{
86 xt_unregister_match(target: &mh_mt6_reg);
87}
88
89module_init(mh_mt6_init);
90module_exit(mh_mt6_exit);
91

source code of linux/net/ipv6/netfilter/ip6t_mh.c