net/ipv4/netfilter/ipt_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_ipv4/ipt_mac.h>
  16 #include <linux/netfilter_ipv4/ip_tables.h>
  17
  18 MODULE_LICENSE("GPL");
  19 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  20 MODULE_DESCRIPTION("iptables mac matching module");
  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       int *hotdrop)
  29 {
  30     const struct ipt_mac_info *info = matchinfo;
  31
  32     /* Is mac pointer valid? */
  33     return (skb->mac.raw >= skb->head
  34             && (skb->mac.raw + ETH_HLEN) <= skb->data
  35             /* If so, compare... */
  36             && ((memcmp(eth_hdr(skb)->h_source, info->srcaddr, ETH_ALEN)
  37                 == 0) ^ info->invert));
  38 }
  39
  40 static int
  41 ipt_mac_checkentry(const char *tablename,
  42                    const struct ipt_ip *ip,
  43                    void *matchinfo,
  44                    unsigned int matchsize,
  45                    unsigned int hook_mask)
  46 {
  47         /* FORWARD isn't always valid, but it's nice to be able to do --RR */
  48         if (hook_mask
  49             & ~((1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_IN)
  50                 | (1 << NF_IP_FORWARD))) {
  51                 printk("ipt_mac: only valid for PRE_ROUTING, LOCAL_IN or FORWARD.\n");
  52                 return 0;
  53         }
  54
  55         if (matchsize != IPT_ALIGN(sizeof(struct ipt_mac_info)))
  56                 return 0;
  57
  58         return 1;
  59 }
  60
  61 static struct ipt_match mac_match = {
  62         .name           = "mac",
  63         .match          = &match,
  64         .checkentry     = &ipt_mac_checkentry,
  65         .me             = THIS_MODULE,
  66 };
  67
  68 static int __init init(void)
  69 {
  70         return ipt_register_match(&mac_match);
  71 }
  72
  73 static void __exit fini(void)
  74 {
  75         ipt_unregister_match(&mac_match);
  76 }
  77
  78 module_init(init);
  79 module_exit(fini);