net/netfilter/xt_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_ipv4.h>
  17 #include <linux/netfilter_ipv6.h>
  18 #include <linux/netfilter/xt_mac.h>
  19 #include <linux/netfilter/x_tables.h>
  20
  21 MODULE_LICENSE("GPL");
  22 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  23 MODULE_DESCRIPTION("iptables mac matching module");
  24 MODULE_ALIAS("ipt_mac");
  25 MODULE_ALIAS("ip6t_mac");
  26
  27 static bool
  28 match(const struct sk_buff *skb,
  29       const struct net_device *in,
  30       const struct net_device *out,
  31       const struct xt_match *match,
  32       const void *matchinfo,
  33       int offset,
  34       unsigned int protoff,
  35       bool *hotdrop)
  36 {
  37     const struct xt_mac_info *info = matchinfo;
  38
  39     /* Is mac pointer valid? */
  40     return skb_mac_header(skb) >= skb->head &&
  41            skb_mac_header(skb) + ETH_HLEN <= skb->data
  42            /* If so, compare... */
  43            && ((!compare_ether_addr(eth_hdr(skb)->h_source, info->srcaddr))
  44                 ^ info->invert);
  45 }
  46
  47 static struct xt_match xt_mac_match[] __read_mostly = {
  48         {
  49                 .name           = "mac",
  50                 .family         = AF_INET,
  51                 .match          = match,
  52                 .matchsize      = sizeof(struct xt_mac_info),
  53                 .hooks          = (1 << NF_IP_PRE_ROUTING) |
  54                                   (1 << NF_IP_LOCAL_IN) |
  55                                   (1 << NF_IP_FORWARD),
  56                 .me             = THIS_MODULE,
  57         },
  58         {
  59                 .name           = "mac",
  60                 .family         = AF_INET6,
  61                 .match          = match,
  62                 .matchsize      = sizeof(struct xt_mac_info),
  63                 .hooks          = (1 << NF_IP6_PRE_ROUTING) |
  64                                   (1 << NF_IP6_LOCAL_IN) |
  65                                   (1 << NF_IP6_FORWARD),
  66                 .me             = THIS_MODULE,
  67         },
  68 };
  69
  70 static int __init xt_mac_init(void)
  71 {
  72         return xt_register_matches(xt_mac_match, ARRAY_SIZE(xt_mac_match));
  73 }
  74
  75 static void __exit xt_mac_fini(void)
  76 {
  77         xt_unregister_matches(xt_mac_match, ARRAY_SIZE(xt_mac_match));
  78 }
  79
  80 module_init(xt_mac_init);
  81 module_exit(xt_mac_fini);