Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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, |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 127 | const void *ip, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |