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("IPv6 EUI64 address checking match");
  19 MODULE_LICENSE("GPL");
  20 MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
  21
  22 static bool
  23 match(const struct sk_buff *skb,
  24       const struct net_device *in,
  25       const struct net_device *out,
  26       const struct xt_match *match,
  27       const void *matchinfo,
  28       int offset,
  29       unsigned int protoff,
  30       bool *hotdrop)
  31 {
  32         unsigned char eui64[8];
  33         int i = 0;
  34
  35         if (!(skb_mac_header(skb) >= skb->head &&
  36               (skb_mac_header(skb) + ETH_HLEN) <= skb->data) &&
  37             offset != 0) {
  38                 *hotdrop = true;
  39                 return false;
  40         }
  41
  42         memset(eui64, 0, sizeof(eui64));
  43
  44         if (eth_hdr(skb)->h_proto == htons(ETH_P_IPV6)) {
  45                 if (ipv6_hdr(skb)->version == 0x6) {
  46                         memcpy(eui64, eth_hdr(skb)->h_source, 3);
  47                         memcpy(eui64 + 5, eth_hdr(skb)->h_source + 3, 3);
  48                         eui64[3] = 0xff;
  49                         eui64[4] = 0xfe;
  50                         eui64[0] |= 0x02;
  51
  52                         i = 0;
  53                         while ((ipv6_hdr(skb)->saddr.s6_addr[8 + i] == eui64[i])
  54                                && (i < 8))
  55                                 i++;
  56
  57                         if (i == 8)
  58                                 return true;
  59                 }
  60         }
  61
  62         return false;
  63 }
  64
  65 static struct xt_match eui64_match = {
  66         .name           = "eui64",
  67         .family         = AF_INET6,
  68         .match          = match,
  69         .matchsize      = sizeof(int),
  70         .hooks          = (1 << NF_IP6_PRE_ROUTING) | (1 << NF_IP6_LOCAL_IN) |
  71                           (1 << NF_IP6_FORWARD),
  72         .me             = THIS_MODULE,
  73 };
  74
  75 static int __init ip6t_eui64_init(void)
  76 {
  77         return xt_register_match(&eui64_match);
  78 }
  79
  80 static void __exit ip6t_eui64_fini(void)
  81 {
  82         xt_unregister_match(&eui64_match);
  83 }
  84
  85 module_init(ip6t_eui64_init);
  86 module_exit(ip6t_eui64_fini);