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
21 MODULE_DESCRIPTION("Xtables: IPv6 Mobility Header match");
22 MODULE_LICENSE("GPL");
23
24 /* Returns 1 if the type is matched by the range, 0 otherwise */
25 static inline bool
26 type_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
31 static 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, par->thoff, sizeof(_mh), &_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(mhinfo->types[0], mhinfo->types[1], mh->ip6mh_type,
58 !!(mhinfo->invflags & IP6T_MH_INV_TYPE));
59 }
60
61 static 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
69 static 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
79 static int __init mh_mt6_init(void)
80 {
81 return xt_register_match(&mh_mt6_reg);
82 }
83
84 static void __exit mh_mt6_exit(void)
85 {
86 xt_unregister_match(&mh_mt6_reg);
87 }
88
89 module_init(mh_mt6_init);
90 module_exit(mh_mt6_exit);
91
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