net/ipv6/netfilter/ip6t_mac.c

   1 /* Kernel module to match MAC address parameters. */
   2
   3 /* (C) 1999-2001 Paul `Rusty' Russell
   4  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/if_ether.h>
  14 #include <linux/etherdevice.h>
  15
  16 #include <linux/netfilter_ipv6/ip6t_mac.h>
  17 #include <linux/netfilter_ipv6/ip6_tables.h>
  18
  19 MODULE_LICENSE("GPL");
  20 MODULE_DESCRIPTION("MAC address matching module for IPv6");
  21 MODULE_AUTHOR("Netfilter Core Teaam <coreteam@netfilter.org>");
  22
  23 static int
  24 match(const struct sk_buff *skb,
  25       const struct net_device *in,
  26       const struct net_device *out,
  27       const void *matchinfo,
  28       int offset,
  29       unsigned int protoff,
  30       int *hotdrop)
  31 {
  32     const struct ip6t_mac_info *info = matchinfo;
  33
  34     /* Is mac pointer valid? */
  35     return (skb->mac.raw >= skb->head
  36             && (skb->mac.raw + ETH_HLEN) <= skb->data
  37             /* If so, compare... */
  38             && ((!compare_ether_addr(eth_hdr(skb)->h_source, info->srcaddr))
  39                 ^ info->invert));
  40 }
  41
  42 static int
  43 ip6t_mac_checkentry(const char *tablename,
  44                    const struct ip6t_ip6 *ip,
  45                    void *matchinfo,
  46                    unsigned int matchsize,
  47                    unsigned int hook_mask)
  48 {
  49         if (hook_mask
  50             & ~((1 << NF_IP6_PRE_ROUTING) | (1 << NF_IP6_LOCAL_IN)
  51                 | (1 << NF_IP6_FORWARD))) {
  52                 printk("ip6t_mac: only valid for PRE_ROUTING, LOCAL_IN or"
  53                        " FORWARD\n");
  54                 return 0;
  55         }
  56
  57         if (matchsize != IP6T_ALIGN(sizeof(struct ip6t_mac_info)))
  58                 return 0;
  59
  60         return 1;
  61 }
  62
  63 static struct ip6t_match mac_match = {
  64         .name           = "mac",
  65         .match          = &match,
  66         .checkentry     = &ip6t_mac_checkentry,
  67         .me             = THIS_MODULE,
  68 };
  69
  70 static int __init init(void)
  71 {
  72         return ip6t_register_match(&mac_match);
  73 }
  74
  75 static void __exit fini(void)
  76 {
  77         ip6t_unregister_match(&mac_match);
  78 }
  79
  80 module_init(init);
  81 module_exit(fini);