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, struct xt_action_param *par)
  24 {
  25         unsigned char eui64[8];
  26
  27         if (!(skb_mac_header(skb) >= skb->head &&
  28               skb_mac_header(skb) + ETH_HLEN <= skb->data) &&
  29             par->fragoff != 0) {
  30                 par->hotdrop = true;
  31                 return false;
  32         }
  33
  34         memset(eui64, 0, sizeof(eui64));
  35
  36         if (eth_hdr(skb)->h_proto == htons(ETH_P_IPV6)) {
  37                 if (ipv6_hdr(skb)->version == 0x6) {
  38                         memcpy(eui64, eth_hdr(skb)->h_source, 3);
  39                         memcpy(eui64 + 5, eth_hdr(skb)->h_source + 3, 3);
  40                         eui64[3] = 0xff;
  41                         eui64[4] = 0xfe;
  42                         eui64[0] ^= 0x02;
  43
  44                         if (!memcmp(ipv6_hdr(skb)->saddr.s6_addr + 8, eui64,
  45                                     sizeof(eui64)))
  46                                 return true;
  47                 }
  48         }
  49
  50         return false;
  51 }
  52
  53 static struct xt_match eui64_mt6_reg __read_mostly = {
  54         .name           = "eui64",
  55         .family         = NFPROTO_IPV6,
  56         .match          = eui64_mt6,
  57         .matchsize      = sizeof(int),
  58         .hooks          = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_IN) |
  59                           (1 << NF_INET_FORWARD),
  60         .me             = THIS_MODULE,
  61 };
  62
  63 static int __init eui64_mt6_init(void)
  64 {
  65         return xt_register_match(&eui64_mt6_reg);
  66 }
  67
  68 static void __exit eui64_mt6_exit(void)
  69 {
  70         xt_unregister_match(&eui64_mt6_reg);
  71 }
  72
  73 module_init(eui64_mt6_init);
  74 module_exit(eui64_mt6_exit);