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1da177e4 LT |
1 | /* ipv6header match - matches IPv6 packets based |
2 | on whether they contain certain headers */ | |
3 | ||
4 | /* Original idea: Brad Chapman | |
5 | * Rewritten by: Andras Kis-Szabo <kisza@sch.bme.hu> */ | |
6 | ||
7 | /* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu> | |
8 | * | |
9 | * This program is free software; you can redistribute it and/or modify | |
10 | * it under the terms of the GNU General Public License version 2 as | |
11 | * published by the Free Software Foundation. | |
12 | */ | |
13 | ||
14 | #include <linux/module.h> | |
15 | #include <linux/skbuff.h> | |
16 | #include <linux/ipv6.h> | |
17 | #include <linux/types.h> | |
18 | #include <net/checksum.h> | |
19 | #include <net/ipv6.h> | |
20 | ||
21 | #include <linux/netfilter_ipv6/ip6_tables.h> | |
22 | #include <linux/netfilter_ipv6/ip6t_ipv6header.h> | |
23 | ||
24 | MODULE_LICENSE("GPL"); | |
25 | MODULE_DESCRIPTION("IPv6 headers match"); | |
26 | MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>"); | |
27 | ||
28 | static int | |
29 | ipv6header_match(const struct sk_buff *skb, | |
30 | const struct net_device *in, | |
31 | const struct net_device *out, | |
32 | const void *matchinfo, | |
33 | int offset, | |
34 | unsigned int protoff, | |
35 | int *hotdrop) | |
36 | { | |
37 | const struct ip6t_ipv6header_info *info = matchinfo; | |
38 | unsigned int temp; | |
39 | int len; | |
40 | u8 nexthdr; | |
41 | unsigned int ptr; | |
42 | ||
43 | /* Make sure this isn't an evil packet */ | |
44 | ||
45 | /* type of the 1st exthdr */ | |
46 | nexthdr = skb->nh.ipv6h->nexthdr; | |
47 | /* pointer to the 1st exthdr */ | |
48 | ptr = sizeof(struct ipv6hdr); | |
49 | /* available length */ | |
50 | len = skb->len - ptr; | |
51 | temp = 0; | |
52 | ||
53 | while (ip6t_ext_hdr(nexthdr)) { | |
54 | struct ipv6_opt_hdr _hdr, *hp; | |
55 | int hdrlen; | |
56 | ||
57 | /* Is there enough space for the next ext header? */ | |
58 | if (len < (int)sizeof(struct ipv6_opt_hdr)) | |
59 | return 0; | |
60 | /* No more exthdr -> evaluate */ | |
61 | if (nexthdr == NEXTHDR_NONE) { | |
62 | temp |= MASK_NONE; | |
63 | break; | |
64 | } | |
65 | /* ESP -> evaluate */ | |
66 | if (nexthdr == NEXTHDR_ESP) { | |
67 | temp |= MASK_ESP; | |
68 | break; | |
69 | } | |
70 | ||
71 | hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr); | |
72 | BUG_ON(hp == NULL); | |
73 | ||
74 | /* Calculate the header length */ | |
75 | if (nexthdr == NEXTHDR_FRAGMENT) { | |
76 | hdrlen = 8; | |
77 | } else if (nexthdr == NEXTHDR_AUTH) | |
78 | hdrlen = (hp->hdrlen+2)<<2; | |
79 | else | |
80 | hdrlen = ipv6_optlen(hp); | |
81 | ||
82 | /* set the flag */ | |
83 | switch (nexthdr){ | |
84 | case NEXTHDR_HOP: | |
85 | temp |= MASK_HOPOPTS; | |
86 | break; | |
87 | case NEXTHDR_ROUTING: | |
88 | temp |= MASK_ROUTING; | |
89 | break; | |
90 | case NEXTHDR_FRAGMENT: | |
91 | temp |= MASK_FRAGMENT; | |
92 | break; | |
93 | case NEXTHDR_AUTH: | |
94 | temp |= MASK_AH; | |
95 | break; | |
96 | case NEXTHDR_DEST: | |
97 | temp |= MASK_DSTOPTS; | |
98 | break; | |
99 | default: | |
100 | return 0; | |
101 | break; | |
102 | } | |
103 | ||
104 | nexthdr = hp->nexthdr; | |
105 | len -= hdrlen; | |
106 | ptr += hdrlen; | |
107 | if (ptr > skb->len) | |
108 | break; | |
109 | } | |
110 | ||
111 | if ( (nexthdr != NEXTHDR_NONE ) && (nexthdr != NEXTHDR_ESP) ) | |
112 | temp |= MASK_PROTO; | |
113 | ||
114 | if (info->modeflag) | |
115 | return !((temp ^ info->matchflags ^ info->invflags) | |
116 | & info->matchflags); | |
117 | else { | |
118 | if (info->invflags) | |
119 | return temp != info->matchflags; | |
120 | else | |
121 | return temp == info->matchflags; | |
122 | } | |
123 | } | |
124 | ||
125 | static int | |
126 | ipv6header_checkentry(const char *tablename, | |
127 | const struct ip6t_ip6 *ip, | |
128 | void *matchinfo, | |
129 | unsigned int matchsize, | |
130 | unsigned int hook_mask) | |
131 | { | |
132 | const struct ip6t_ipv6header_info *info = matchinfo; | |
133 | ||
134 | /* Check for obvious errors */ | |
135 | /* This match is valid in all hooks! */ | |
136 | if (matchsize != IP6T_ALIGN(sizeof(struct ip6t_ipv6header_info))) | |
137 | return 0; | |
138 | ||
139 | /* invflags is 0 or 0xff in hard mode */ | |
140 | if ((!info->modeflag) && info->invflags != 0x00 | |
141 | && info->invflags != 0xFF) | |
142 | return 0; | |
143 | ||
144 | return 1; | |
145 | } | |
146 | ||
147 | static struct ip6t_match ip6t_ipv6header_match = { | |
148 | .name = "ipv6header", | |
149 | .match = &ipv6header_match, | |
150 | .checkentry = &ipv6header_checkentry, | |
151 | .destroy = NULL, | |
152 | .me = THIS_MODULE, | |
153 | }; | |
154 | ||
155 | static int __init ipv6header_init(void) | |
156 | { | |
157 | return ip6t_register_match(&ip6t_ipv6header_match); | |
158 | } | |
159 | ||
160 | static void __exit ipv6header_exit(void) | |
161 | { | |
162 | ip6t_unregister_match(&ip6t_ipv6header_match); | |
163 | } | |
164 | ||
165 | module_init(ipv6header_init); | |
166 | module_exit(ipv6header_exit); | |
167 |