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 matchsize,
  59            unsigned int hook_mask)
  60 {
  61         struct xt_connmark_info *cm = (struct xt_connmark_info *)matchinfo;
  62
  63         if (cm->mark > 0xffffffff || cm->mask > 0xffffffff) {
  64                 printk(KERN_WARNING "connmark: only support 32bit mark\n");
  65                 return 0;
  66         }
  67 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
  68         if (nf_ct_l3proto_try_module_get(match->family) < 0) {
  69                 printk(KERN_WARNING "can't load nf_conntrack support for "
  70                                     "proto=%d\n", match->family);
  71                 return 0;
  72         }
  73 #endif
  74         return 1;
  75 }
  76
  77 static void
  78 destroy(const struct xt_match *match, void *matchinfo, unsigned int matchsize)
  79 {
  80 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
  81         nf_ct_l3proto_module_put(match->family);
  82 #endif
  83 }
  84
  85 static struct xt_match connmark_match = {
  86         .name           = "connmark",
  87         .match          = match,
  88         .matchsize      = sizeof(struct xt_connmark_info),
  89         .checkentry     = checkentry,
  90         .destroy        = destroy,
  91         .family         = AF_INET,
  92         .me             = THIS_MODULE
  93 };
  94
  95 static struct xt_match connmark6_match = {
  96         .name           = "connmark",
  97         .match          = match,
  98         .matchsize      = sizeof(struct xt_connmark_info),
  99         .checkentry     = checkentry,
 100         .destroy        = destroy,
 101         .family         = AF_INET6,
 102         .me             = THIS_MODULE
 103 };
 104
 105 static int __init init(void)
 106 {
 107         int ret;
 108
 109         need_conntrack();
 110
 111         ret = xt_register_match(&connmark_match);
 112         if (ret)
 113                 return ret;
 114
 115         ret = xt_register_match(&connmark6_match);
 116         if (ret)
 117                 xt_unregister_match(&connmark_match);
 118         return ret;
 119 }
 120
 121 static void __exit fini(void)
 122 {
 123         xt_unregister_match(&connmark6_match);
 124         xt_unregister_match(&connmark_match);
 125 }
 126
 127 module_init(init);
 128 module_exit(fini);