net/ipv4/netfilter/ipt_connmark.c

   1 /* This kernel module matches connection mark values set by the
   2  * CONNMARK target
   3  *
   4  * Copyright (C) 2002,2004 MARA Systems AB <http://www.marasystems.com>
   5  * by Henrik Nordstrom <hno@marasystems.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  */
  21
  22 #include <linux/module.h>
  23 #include <linux/skbuff.h>
  24
  25 MODULE_AUTHOR("Henrik Nordstrom <hno@marasytems.com>");
  26 MODULE_DESCRIPTION("IP tables connmark match module");
  27 MODULE_LICENSE("GPL");
  28
  29 #include <linux/netfilter_ipv4/ip_tables.h>
  30 #include <linux/netfilter_ipv4/ipt_connmark.h>
  31 #include <linux/netfilter_ipv4/ip_conntrack.h>
  32
  33 static int
  34 match(const struct sk_buff *skb,
  35       const struct net_device *in,
  36       const struct net_device *out,
  37       const void *matchinfo,
  38       int offset,
  39       int *hotdrop)
  40 {
  41         const struct ipt_connmark_info *info = matchinfo;
  42         enum ip_conntrack_info ctinfo;
  43         struct ip_conntrack *ct = ip_conntrack_get((struct sk_buff *)skb, &ctinfo);
  44         if (!ct)
  45                 return 0;
  46
  47         return ((ct->mark & info->mask) == info->mark) ^ info->invert;
  48 }
  49
  50 static int
  51 checkentry(const char *tablename,
  52            const struct ipt_ip *ip,
  53            void *matchinfo,
  54            unsigned int matchsize,
  55            unsigned int hook_mask)
  56 {
  57         if (matchsize != IPT_ALIGN(sizeof(struct ipt_connmark_info)))
  58                 return 0;
  59
  60         return 1;
  61 }
  62
  63 static struct ipt_match connmark_match = {
  64         .name = "connmark",
  65         .match = &match,
  66         .checkentry = &checkentry,
  67         .me = THIS_MODULE
  68 };
  69
  70 static int __init init(void)
  71 {
  72         return ipt_register_match(&connmark_match);
  73 }
  74
  75 static void __exit fini(void)
  76 {
  77         ipt_unregister_match(&connmark_match);
  78 }
  79
  80 module_init(init);
  81 module_exit(fini);