net/netfilter/xt_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 MODULE_ALIAS("ipt_connmark");
  29
  30 #include <linux/netfilter/x_tables.h>
  31 #include <linux/netfilter/xt_connmark.h>
  32 #include <net/netfilter/nf_conntrack_compat.h>
  33
  34 static int
  35 match(const struct sk_buff *skb,
  36       const struct net_device *in,
  37       const struct net_device *out,
  38       const void *matchinfo,
  39       int offset,
  40       unsigned int protoff,
  41       int *hotdrop)
  42 {
  43         const struct xt_connmark_info *info = matchinfo;
  44         u_int32_t ctinfo;
  45         const u_int32_t *ctmark = nf_ct_get_mark(skb, &ctinfo);
  46         if (!ctmark)
  47                 return 0;
  48
  49         return (((*ctmark) & info->mask) == info->mark) ^ info->invert;
  50 }
  51
  52 static int
  53 checkentry(const char *tablename,
  54            const void *ip,
  55            void *matchinfo,
  56            unsigned int matchsize,
  57            unsigned int hook_mask)
  58 {
  59         struct xt_connmark_info *cm = (struct xt_connmark_info *)matchinfo;
  60
  61         if (cm->mark > 0xffffffff || cm->mask > 0xffffffff) {
  62                 printk(KERN_WARNING "connmark: only support 32bit mark\n");
  63                 return 0;
  64         }
  65         return 1;
  66 }
  67
  68 static struct xt_match connmark_match = {
  69         .name           = "connmark",
  70         .match          = match,
  71         .matchsize      = sizeof(struct xt_connmark_info),
  72         .checkentry     = checkentry,
  73         .me             = THIS_MODULE
  74 };
  75
  76 static struct xt_match connmark6_match = {
  77         .name           = "connmark",
  78         .match          = match,
  79         .matchsize      = sizeof(struct xt_connmark_info),
  80         .checkentry     = checkentry,
  81         .me             = THIS_MODULE
  82 };
  83
  84 static int __init init(void)
  85 {
  86         int ret;
  87
  88         need_conntrack();
  89
  90         ret = xt_register_match(AF_INET, &connmark_match);
  91         if (ret)
  92                 return ret;
  93
  94         ret = xt_register_match(AF_INET6, &connmark6_match);
  95         if (ret)
  96                 xt_unregister_match(AF_INET, &connmark_match);
  97         return ret;
  98 }
  99
 100 static void __exit fini(void)
 101 {
 102         xt_unregister_match(AF_INET6, &connmark6_match);
 103         xt_unregister_match(AF_INET, &connmark_match);
 104 }
 105
 106 module_init(init);
 107 module_exit(fini);