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/xt_mac.h>
  18 #include <linux/netfilter/x_tables.h>
  19
  20 MODULE_LICENSE("GPL");
  21 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  22 MODULE_DESCRIPTION("iptables mac matching module");
  23 MODULE_ALIAS("ipt_mac");
  24 MODULE_ALIAS("ip6t_mac");
  25
  26 static int
  27 match(const struct sk_buff *skb,
  28       const struct net_device *in,
  29       const struct net_device *out,
  30       const void *matchinfo,
  31       int offset,
  32       unsigned int protoff,
  33       int *hotdrop)
  34 {
  35     const struct xt_mac_info *info = matchinfo;
  36
  37     /* Is mac pointer valid? */
  38     return (skb->mac.raw >= skb->head
  39             && (skb->mac.raw + ETH_HLEN) <= skb->data
  40             /* If so, compare... */
  41             && ((!compare_ether_addr(eth_hdr(skb)->h_source, info->srcaddr))
  42                 ^ info->invert));
  43 }
  44
  45 static int
  46 ipt_mac_checkentry(const char *tablename,
  47                    const void *inf,
  48                    void *matchinfo,
  49                    unsigned int matchsize,
  50                    unsigned int hook_mask)
  51 {
  52         /* FORWARD isn't always valid, but it's nice to be able to do --RR */
  53         if (hook_mask
  54             & ~((1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_IN)
  55                 | (1 << NF_IP_FORWARD))) {
  56                 printk("xt_mac: only valid for PRE_ROUTING, LOCAL_IN or FORWARD.\n");
  57                 return 0;
  58         }
  59
  60         if (matchsize != XT_ALIGN(sizeof(struct xt_mac_info)))
  61                 return 0;
  62
  63         return 1;
  64 }
  65
  66 static struct xt_match mac_match = {
  67         .name           = "mac",
  68         .match          = &match,
  69         .checkentry     = &ipt_mac_checkentry,
  70         .me             = THIS_MODULE,
  71 };
  72 static struct xt_match mac6_match = {
  73         .name           = "mac",
  74         .match          = &match,
  75         .checkentry     = &ipt_mac_checkentry,
  76         .me             = THIS_MODULE,
  77 };
  78
  79 static int __init init(void)
  80 {
  81         int ret;
  82         ret = xt_register_match(AF_INET, &mac_match);
  83         if (ret)
  84                 return ret;
  85
  86         ret = xt_register_match(AF_INET6, &mac6_match);
  87         if (ret)
  88                 xt_unregister_match(AF_INET, &mac_match);
  89
  90         return ret;
  91 }
  92
  93 static void __exit fini(void)
  94 {
  95         xt_unregister_match(AF_INET, &mac_match);
  96         xt_unregister_match(AF_INET6, &mac6_match);
  97 }
  98
  99 module_init(init);
 100 module_exit(fini);