net/ipv6/netfilter/ip6t_eui64.c

   1 /* Kernel module to match EUI64 address parameters. */
   2
   3 /* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/skbuff.h>
  12 #include <linux/ipv6.h>
  13 #include <linux/if_ether.h>
  14
  15 #include <linux/netfilter/x_tables.h>
  16 #include <linux/netfilter_ipv6/ip6_tables.h>
  17
  18 MODULE_DESCRIPTION("Xtables: IPv6 EUI64 address match");
  19 MODULE_LICENSE("GPL");
  20 MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
  21
  22 static bool
  23 eui64_mt6(const struct sk_buff *skb, const struct net_device *in,
  24           const struct net_device *out, const struct xt_match *match,
  25           const void *matchinfo, int offset, unsigned int protoff,
  26           bool *hotdrop)
  27 {
  28         unsigned char eui64[8];
  29         int i = 0;
  30
  31         if (!(skb_mac_header(skb) >= skb->head &&
  32               skb_mac_header(skb) + ETH_HLEN <= skb->data) &&
  33             offset != 0) {
  34                 *hotdrop = true;
  35                 return false;
  36         }
  37
  38         memset(eui64, 0, sizeof(eui64));
  39
  40         if (eth_hdr(skb)->h_proto == htons(ETH_P_IPV6)) {
  41                 if (ipv6_hdr(skb)->version == 0x6) {
  42                         memcpy(eui64, eth_hdr(skb)->h_source, 3);
  43                         memcpy(eui64 + 5, eth_hdr(skb)->h_source + 3, 3);
  44                         eui64[3] = 0xff;
  45                         eui64[4] = 0xfe;
  46                         eui64[0] ^= 0x02;
  47
  48                         i = 0;
  49                         while (ipv6_hdr(skb)->saddr.s6_addr[8 + i] == eui64[i]
  50                                && i < 8)
  51                                 i++;
  52
  53                         if (i == 8)
  54                                 return true;
  55                 }
  56         }
  57
  58         return false;
  59 }
  60
  61 static struct xt_match eui64_mt6_reg __read_mostly = {
  62         .name           = "eui64",
  63         .family         = AF_INET6,
  64         .match          = eui64_mt6,
  65         .matchsize      = sizeof(int),
  66         .hooks          = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_IN) |
  67                           (1 << NF_INET_FORWARD),
  68         .me             = THIS_MODULE,
  69 };
  70
  71 static int __init eui64_mt6_init(void)
  72 {
  73         return xt_register_match(&eui64_mt6_reg);
  74 }
  75
  76 static void __exit eui64_mt6_exit(void)
  77 {
  78         xt_unregister_match(&eui64_mt6_reg);
  79 }
  80
  81 module_init(eui64_mt6_init);
  82 module_exit(eui64_mt6_exit);