net/ipv4/netfilter/ipt_pkttype.c

   1 /* (C) 1999-2001 Michal Ludvig <michal@logix.cz>
   2  *
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License version 2 as
   5  * published by the Free Software Foundation.
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/skbuff.h>
  10 #include <linux/if_ether.h>
  11 #include <linux/if_packet.h>
  12
  13 #include <linux/netfilter_ipv4/ipt_pkttype.h>
  14 #include <linux/netfilter_ipv4/ip_tables.h>
  15
  16 MODULE_LICENSE("GPL");
  17 MODULE_AUTHOR("Michal Ludvig <michal@logix.cz>");
  18 MODULE_DESCRIPTION("IP tables match to match on linklayer packet type");
  19
  20 static int match(const struct sk_buff *skb,
  21       const struct net_device *in,
  22       const struct net_device *out,
  23       const void *matchinfo,
  24       int offset,
  25       int *hotdrop)
  26 {
  27     const struct ipt_pkttype_info *info = matchinfo;
  28
  29     return (skb->pkt_type == info->pkttype) ^ info->invert;
  30 }
  31
  32 static int checkentry(const char *tablename,
  33                    const struct ipt_ip *ip,
  34                    void *matchinfo,
  35                    unsigned int matchsize,
  36                    unsigned int hook_mask)
  37 {
  38 /*
  39         if (hook_mask
  40             & ~((1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_IN)
  41                 | (1 << NF_IP_FORWARD))) {
  42                 printk("ipt_pkttype: only valid for PRE_ROUTING, LOCAL_IN or FORWARD.\n");
  43                 return 0;
  44         }
  45 */
  46         if (matchsize != IPT_ALIGN(sizeof(struct ipt_pkttype_info)))
  47                 return 0;
  48
  49         return 1;
  50 }
  51
  52 static struct ipt_match pkttype_match = {
  53         .name           = "pkttype",
  54         .match          = &match,
  55         .checkentry     = &checkentry,
  56         .me             = THIS_MODULE,
  57 };
  58
  59 static int __init init(void)
  60 {
  61         return ipt_register_match(&pkttype_match);
  62 }
  63
  64 static void __exit fini(void)
  65 {
  66         ipt_unregister_match(&pkttype_match);
  67 }
  68
  69 module_init(init);
  70 module_exit(fini);