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, 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 | |
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(target: &mh_mt6_reg); |
82 | } |
83 | |
84 | static void __exit mh_mt6_exit(void) |
85 | { |
86 | xt_unregister_match(target: &mh_mt6_reg); |
87 | } |
88 | |
89 | module_init(mh_mt6_init); |
90 | module_exit(mh_mt6_exit); |
91 | |