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 struct xt_match *match,
  39       const void *matchinfo,
  40       int offset,
  41       unsigned int protoff,
  42       int *hotdrop)
  43 {
  44         const struct xt_connmark_info *info = matchinfo;
  45         u_int32_t ctinfo;
  46         const u_int32_t *ctmark = nf_ct_get_mark(skb, &ctinfo);
  47         if (!ctmark)
  48                 return 0;
  49
  50         return (((*ctmark) & info->mask) == info->mark) ^ info->invert;
  51 }
  52
  53 static int
  54 checkentry(const char *tablename,
  55            const void *ip,
  56            const struct xt_match *match,
  57            void *matchinfo,
  58            unsigned int hook_mask)
  59 {
  60         struct xt_connmark_info *cm = matchinfo;
  61
  62         if (cm->mark > 0xffffffff || cm->mask > 0xffffffff) {
  63                 printk(KERN_WARNING "connmark: only support 32bit mark\n");
  64                 return 0;
  65         }
  66 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
  67         if (nf_ct_l3proto_try_module_get(match->family) < 0) {
  68                 printk(KERN_WARNING "can't load nf_conntrack support for "
  69                                     "proto=%d\n", match->family);
  70                 return 0;
  71         }
  72 #endif
  73         return 1;
  74 }
  75
  76 static void
  77 destroy(const struct xt_match *match, void *matchinfo)
  78 {
  79 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
  80         nf_ct_l3proto_module_put(match->family);
  81 #endif
  82 }
  83
  84 static struct xt_match xt_connmark_match[] = {
  85         {
  86                 .name           = "connmark",
  87                 .family         = AF_INET,
  88                 .checkentry     = checkentry,
  89                 .match          = match,
  90                 .destroy        = destroy,
  91                 .matchsize      = sizeof(struct xt_connmark_info),
  92                 .me             = THIS_MODULE
  93         },
  94         {
  95                 .name           = "connmark",
  96                 .family         = AF_INET6,
  97                 .checkentry     = checkentry,
  98                 .match          = match,
  99                 .destroy        = destroy,
 100                 .matchsize      = sizeof(struct xt_connmark_info),
 101                 .me             = THIS_MODULE
 102         },
 103 };
 104
 105 static int __init xt_connmark_init(void)
 106 {
 107         need_conntrack();
 108         return xt_register_matches(xt_connmark_match,
 109                                    ARRAY_SIZE(xt_connmark_match));
 110 }
 111
 112 static void __exit xt_connmark_fini(void)
 113 {
 114         xt_register_matches(xt_connmark_match, ARRAY_SIZE(xt_connmark_match));
 115 }
 116
 117 module_init(xt_connmark_init);
 118 module_exit(xt_connmark_fini);