net/netfilter/xt_mac.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Kernel module to match MAC address parameters. */
   3
   4 /* (C) 1999-2001 Paul `Rusty' Russell
   5  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/skbuff.h>
  10 #include <linux/if_arp.h>
  11 #include <linux/if_ether.h>
  12 #include <linux/etherdevice.h>
  13
  14 #include <linux/netfilter_ipv4.h>
  15 #include <linux/netfilter_ipv6.h>
  16 #include <linux/netfilter/xt_mac.h>
  17 #include <linux/netfilter/x_tables.h>
  18
  19 MODULE_LICENSE("GPL");
  20 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  21 MODULE_DESCRIPTION("Xtables: MAC address match");
  22 MODULE_ALIAS("ipt_mac");
  23 MODULE_ALIAS("ip6t_mac");
  24
  25 static bool mac_mt(const struct sk_buff *skb, struct xt_action_param *par)
  26 {
  27         const struct xt_mac_info *info = par->matchinfo;
  28         bool ret;
  29
  30         if (skb->dev == NULL || skb->dev->type != ARPHRD_ETHER)
  31                 return false;
  32         if (skb_mac_header(skb) < skb->head)
  33                 return false;
  34         if (skb_mac_header(skb) + ETH_HLEN > skb->data)
  35                 return false;
  36         ret  = ether_addr_equal(eth_hdr(skb)->h_source, info->srcaddr);
  37         ret ^= info->invert;
  38         return ret;
  39 }
  40
  41 static struct xt_match mac_mt_reg __read_mostly = {
  42         .name      = "mac",
  43         .revision  = 0,
  44         .family    = NFPROTO_UNSPEC,
  45         .match     = mac_mt,
  46         .matchsize = sizeof(struct xt_mac_info),
  47         .hooks     = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_IN) |
  48                      (1 << NF_INET_FORWARD),
  49         .me        = THIS_MODULE,
  50 };
  51
  52 static int __init mac_mt_init(void)
  53 {
  54         return xt_register_match(&mac_mt_reg);
  55 }
  56
  57 static void __exit mac_mt_exit(void)
  58 {
  59         xt_unregister_match(&mac_mt_reg);
  60 }
  61
  62 module_init(mac_mt_init);
  63 module_exit(mac_mt_exit);