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
  15 #include <linux/netfilter_ipv6/ip6t_mac.h>
  16 #include <linux/netfilter_ipv6/ip6_tables.h>
  17
  18 MODULE_LICENSE("GPL");
  19 MODULE_DESCRIPTION("MAC address matching module for IPv6");
  20 MODULE_AUTHOR("Netfilter Core Teaam <coreteam@netfilter.org>");
  21
  22 static int
  23 match(const struct sk_buff *skb,
  24       const struct net_device *in,
  25       const struct net_device *out,
  26       const void *matchinfo,
  27       int offset,
  28       unsigned int protoff,
  29       int *hotdrop)
  30 {
  31     const struct ip6t_mac_info *info = matchinfo;
  32
  33     /* Is mac pointer valid? */
  34     return (skb->mac.raw >= skb->head
  35             && (skb->mac.raw + ETH_HLEN) <= skb->data
  36             /* If so, compare... */
  37             && ((memcmp(eth_hdr(skb)->h_source, info->srcaddr, ETH_ALEN)
  38                 == 0) ^ info->invert));
  39 }
  40
  41 static int
  42 ip6t_mac_checkentry(const char *tablename,
  43                    const struct ip6t_ip6 *ip,
  44                    void *matchinfo,
  45                    unsigned int matchsize,
  46                    unsigned int hook_mask)
  47 {
  48         if (hook_mask
  49             & ~((1 << NF_IP6_PRE_ROUTING) | (1 << NF_IP6_LOCAL_IN)
  50                 | (1 << NF_IP6_FORWARD))) {
  51                 printk("ip6t_mac: only valid for PRE_ROUTING, LOCAL_IN or"
  52                        " FORWARD\n");
  53                 return 0;
  54         }
  55
  56         if (matchsize != IP6T_ALIGN(sizeof(struct ip6t_mac_info)))
  57                 return 0;
  58
  59         return 1;
  60 }
  61
  62 static struct ip6t_match mac_match = {
  63         .name           = "mac",
  64         .match          = &match,
  65         .checkentry     = &ip6t_mac_checkentry,
  66         .me             = THIS_MODULE,
  67 };
  68
  69 static int __init init(void)
  70 {
  71         return ip6t_register_match(&mac_match);
  72 }
  73
  74 static void __exit fini(void)
  75 {
  76         ip6t_unregister_match(&mac_match);
  77 }
  78
  79 module_init(init);
  80 module_exit(fini);