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a0ca215a MN |
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("ip6t_tables match for MH"); | |
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 */ | |
1d93a9cb JE |
34 | static inline bool |
35 | type_match(u_int8_t min, u_int8_t max, u_int8_t type, bool invert) | |
a0ca215a | 36 | { |
1d93a9cb | 37 | return (type >= min && type <= max) ^ invert; |
a0ca215a MN |
38 | } |
39 | ||
1d93a9cb | 40 | static bool |
a0ca215a MN |
41 | match(const struct sk_buff *skb, |
42 | const struct net_device *in, | |
43 | const struct net_device *out, | |
44 | const struct xt_match *match, | |
45 | const void *matchinfo, | |
46 | int offset, | |
47 | unsigned int protoff, | |
cff533ac | 48 | bool *hotdrop) |
a0ca215a | 49 | { |
a47362a2 JE |
50 | struct ip6_mh _mh; |
51 | const struct ip6_mh *mh; | |
a0ca215a MN |
52 | const struct ip6t_mh *mhinfo = matchinfo; |
53 | ||
54 | /* Must not be a fragment. */ | |
55 | if (offset) | |
1d93a9cb | 56 | return false; |
a0ca215a MN |
57 | |
58 | mh = skb_header_pointer(skb, protoff, sizeof(_mh), &_mh); | |
59 | if (mh == NULL) { | |
60 | /* We've been asked to examine this packet, and we | |
61 | can't. Hence, no choice but to drop. */ | |
62 | duprintf("Dropping evil MH tinygram.\n"); | |
cff533ac | 63 | *hotdrop = true; |
1d93a9cb | 64 | return false; |
a0ca215a MN |
65 | } |
66 | ||
138939e0 MN |
67 | if (mh->ip6mh_proto != IPPROTO_NONE) { |
68 | duprintf("Dropping invalid MH Payload Proto: %u\n", | |
69 | mh->ip6mh_proto); | |
cff533ac | 70 | *hotdrop = true; |
1d93a9cb | 71 | return false; |
138939e0 MN |
72 | } |
73 | ||
a0ca215a MN |
74 | return type_match(mhinfo->types[0], mhinfo->types[1], mh->ip6mh_type, |
75 | !!(mhinfo->invflags & IP6T_MH_INV_TYPE)); | |
76 | } | |
77 | ||
78 | /* Called when user tries to insert an entry of this type. */ | |
ccb79bdc | 79 | static bool |
a0ca215a MN |
80 | mh_checkentry(const char *tablename, |
81 | const void *entry, | |
82 | const struct xt_match *match, | |
83 | void *matchinfo, | |
84 | unsigned int hook_mask) | |
85 | { | |
86 | const struct ip6t_mh *mhinfo = matchinfo; | |
87 | ||
88 | /* Must specify no unknown invflags */ | |
89 | return !(mhinfo->invflags & ~IP6T_MH_INV_MASK); | |
90 | } | |
91 | ||
92 | static struct xt_match mh_match = { | |
93 | .name = "mh", | |
94 | .family = AF_INET6, | |
95 | .checkentry = mh_checkentry, | |
96 | .match = match, | |
97 | .matchsize = sizeof(struct ip6t_mh), | |
98 | .proto = IPPROTO_MH, | |
99 | .me = THIS_MODULE, | |
100 | }; | |
101 | ||
102 | static int __init ip6t_mh_init(void) | |
103 | { | |
104 | return xt_register_match(&mh_match); | |
105 | } | |
106 | ||
107 | static void __exit ip6t_mh_fini(void) | |
108 | { | |
109 | xt_unregister_match(&mh_match); | |
110 | } | |
111 | ||
112 | module_init(ip6t_mh_init); | |
113 | module_exit(ip6t_mh_fini); |