Commit | Line | Data |
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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, | |
c4986734 | 32 | const struct xt_match *match, |
1da177e4 LT |
33 | const void *matchinfo, |
34 | int offset, | |
35 | unsigned int protoff, | |
36 | int *hotdrop) | |
37 | { | |
38 | const struct ip6t_ipv6header_info *info = matchinfo; | |
39 | unsigned int temp; | |
40 | int len; | |
41 | u8 nexthdr; | |
42 | unsigned int ptr; | |
43 | ||
44 | /* Make sure this isn't an evil packet */ | |
45 | ||
46 | /* type of the 1st exthdr */ | |
47 | nexthdr = skb->nh.ipv6h->nexthdr; | |
48 | /* pointer to the 1st exthdr */ | |
49 | ptr = sizeof(struct ipv6hdr); | |
50 | /* available length */ | |
51 | len = skb->len - ptr; | |
52 | temp = 0; | |
53 | ||
f0daaa65 | 54 | while (ip6t_ext_hdr(nexthdr)) { |
1da177e4 | 55 | struct ipv6_opt_hdr _hdr, *hp; |
f0daaa65 | 56 | int hdrlen; |
1da177e4 LT |
57 | |
58 | /* Is there enough space for the next ext header? */ | |
f0daaa65 YK |
59 | if (len < (int)sizeof(struct ipv6_opt_hdr)) |
60 | return 0; | |
1da177e4 | 61 | /* No more exthdr -> evaluate */ |
f0daaa65 | 62 | if (nexthdr == NEXTHDR_NONE) { |
1da177e4 LT |
63 | temp |= MASK_NONE; |
64 | break; | |
65 | } | |
66 | /* ESP -> evaluate */ | |
f0daaa65 | 67 | if (nexthdr == NEXTHDR_ESP) { |
1da177e4 LT |
68 | temp |= MASK_ESP; |
69 | break; | |
70 | } | |
71 | ||
72 | hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr); | |
73 | BUG_ON(hp == NULL); | |
74 | ||
75 | /* Calculate the header length */ | |
f0daaa65 YK |
76 | if (nexthdr == NEXTHDR_FRAGMENT) { |
77 | hdrlen = 8; | |
78 | } else if (nexthdr == NEXTHDR_AUTH) | |
79 | hdrlen = (hp->hdrlen + 2) << 2; | |
80 | else | |
81 | hdrlen = ipv6_optlen(hp); | |
1da177e4 LT |
82 | |
83 | /* set the flag */ | |
f0daaa65 YK |
84 | switch (nexthdr) { |
85 | case NEXTHDR_HOP: | |
86 | temp |= MASK_HOPOPTS; | |
87 | break; | |
88 | case NEXTHDR_ROUTING: | |
89 | temp |= MASK_ROUTING; | |
90 | break; | |
91 | case NEXTHDR_FRAGMENT: | |
92 | temp |= MASK_FRAGMENT; | |
93 | break; | |
94 | case NEXTHDR_AUTH: | |
95 | temp |= MASK_AH; | |
96 | break; | |
97 | case NEXTHDR_DEST: | |
98 | temp |= MASK_DSTOPTS; | |
99 | break; | |
100 | default: | |
101 | return 0; | |
102 | break; | |
1da177e4 LT |
103 | } |
104 | ||
f0daaa65 YK |
105 | nexthdr = hp->nexthdr; |
106 | len -= hdrlen; | |
107 | ptr += hdrlen; | |
1da177e4 LT |
108 | if (ptr > skb->len) |
109 | break; | |
f0daaa65 | 110 | } |
1da177e4 | 111 | |
f0daaa65 | 112 | if ((nexthdr != NEXTHDR_NONE) && (nexthdr != NEXTHDR_ESP)) |
1da177e4 LT |
113 | temp |= MASK_PROTO; |
114 | ||
115 | if (info->modeflag) | |
116 | return !((temp ^ info->matchflags ^ info->invflags) | |
117 | & info->matchflags); | |
118 | else { | |
119 | if (info->invflags) | |
120 | return temp != info->matchflags; | |
121 | else | |
122 | return temp == info->matchflags; | |
123 | } | |
124 | } | |
125 | ||
126 | static int | |
127 | ipv6header_checkentry(const char *tablename, | |
2e4e6a17 | 128 | const void *ip, |
c4986734 | 129 | const struct xt_match *match, |
1da177e4 LT |
130 | void *matchinfo, |
131 | unsigned int matchsize, | |
132 | unsigned int hook_mask) | |
133 | { | |
134 | const struct ip6t_ipv6header_info *info = matchinfo; | |
135 | ||
1da177e4 | 136 | /* invflags is 0 or 0xff in hard mode */ |
f0daaa65 YK |
137 | if ((!info->modeflag) && info->invflags != 0x00 && |
138 | info->invflags != 0xFF) | |
1da177e4 LT |
139 | return 0; |
140 | ||
141 | return 1; | |
142 | } | |
143 | ||
144 | static struct ip6t_match ip6t_ipv6header_match = { | |
145 | .name = "ipv6header", | |
146 | .match = &ipv6header_match, | |
7f939713 | 147 | .matchsize = sizeof(struct ip6t_ipv6header_info), |
1da177e4 LT |
148 | .checkentry = &ipv6header_checkentry, |
149 | .destroy = NULL, | |
150 | .me = THIS_MODULE, | |
151 | }; | |
152 | ||
f0daaa65 | 153 | static int __init ipv6header_init(void) |
1da177e4 LT |
154 | { |
155 | return ip6t_register_match(&ip6t_ipv6header_match); | |
156 | } | |
157 | ||
158 | static void __exit ipv6header_exit(void) | |
159 | { | |
160 | ip6t_unregister_match(&ip6t_ipv6header_match); | |
161 | } | |
162 | ||
163 | module_init(ipv6header_init); | |
164 | module_exit(ipv6header_exit); |