net/netfilter/xt_CONNMARK.c

   1 /*
   2  *      xt_CONNMARK - Netfilter module to modify the connection mark values
   3  *
   4  *      Copyright (C) 2002,2004 MARA Systems AB <http://www.marasystems.com>
   5  *      by Henrik Nordstrom <hno@marasystems.com>
   6  *      Copyright © CC Computer Consultants GmbH, 2007 - 2008
   7  *      Jan Engelhardt <jengelh@computergmbh.de>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  22  */
  23 #include <linux/module.h>
  24 #include <linux/skbuff.h>
  25 #include <linux/ip.h>
  26 #include <net/checksum.h>
  27
  28 MODULE_AUTHOR("Henrik Nordstrom <hno@marasystems.com>");
  29 MODULE_DESCRIPTION("Xtables: connection mark modification");
  30 MODULE_LICENSE("GPL");
  31 MODULE_ALIAS("ipt_CONNMARK");
  32 MODULE_ALIAS("ip6t_CONNMARK");
  33
  34 #include <linux/netfilter/x_tables.h>
  35 #include <linux/netfilter/xt_CONNMARK.h>
  36 #include <net/netfilter/nf_conntrack_ecache.h>
  37
  38 static unsigned int
  39 connmark_tg(struct sk_buff *skb, const struct xt_target_param *par)
  40 {
  41         const struct xt_connmark_tginfo1 *info = par->targinfo;
  42         enum ip_conntrack_info ctinfo;
  43         struct nf_conn *ct;
  44         u_int32_t newmark;
  45
  46         ct = nf_ct_get(skb, &ctinfo);
  47         if (ct == NULL)
  48                 return XT_CONTINUE;
  49
  50         switch (info->mode) {
  51         case XT_CONNMARK_SET:
  52                 newmark = (ct->mark & ~info->ctmask) ^ info->ctmark;
  53                 if (ct->mark != newmark) {
  54                         ct->mark = newmark;
  55                         nf_conntrack_event_cache(IPCT_MARK, ct);
  56                 }
  57                 break;
  58         case XT_CONNMARK_SAVE:
  59                 newmark = (ct->mark & ~info->ctmask) ^
  60                           (skb->mark & info->nfmask);
  61                 if (ct->mark != newmark) {
  62                         ct->mark = newmark;
  63                         nf_conntrack_event_cache(IPCT_MARK, ct);
  64                 }
  65                 break;
  66         case XT_CONNMARK_RESTORE:
  67                 newmark = (skb->mark & ~info->nfmask) ^
  68                           (ct->mark & info->ctmask);
  69                 skb->mark = newmark;
  70                 break;
  71         }
  72
  73         return XT_CONTINUE;
  74 }
  75
  76 static bool connmark_tg_check(const struct xt_tgchk_param *par)
  77 {
  78         if (nf_ct_l3proto_try_module_get(par->family) < 0) {
  79                 printk(KERN_WARNING "cannot load conntrack support for "
  80                        "proto=%u\n", par->family);
  81                 return false;
  82         }
  83         return true;
  84 }
  85
  86 static void connmark_tg_destroy(const struct xt_tgdtor_param *par)
  87 {
  88         nf_ct_l3proto_module_put(par->family);
  89 }
  90
  91 static struct xt_target connmark_tg_reg __read_mostly = {
  92         .name           = "CONNMARK",
  93         .revision       = 1,
  94         .family         = NFPROTO_UNSPEC,
  95         .checkentry     = connmark_tg_check,
  96         .target         = connmark_tg,
  97         .targetsize     = sizeof(struct xt_connmark_tginfo1),
  98         .destroy        = connmark_tg_destroy,
  99         .me             = THIS_MODULE,
 100 };
 101
 102 static int __init connmark_tg_init(void)
 103 {
 104         return xt_register_target(&connmark_tg_reg);
 105 }
 106
 107 static void __exit connmark_tg_exit(void)
 108 {
 109         xt_unregister_target(&connmark_tg_reg);
 110 }
 111
 112 module_init(connmark_tg_init);
 113 module_exit(connmark_tg_exit);