net/netfilter/xt_connmark.c

   1 /*
   2  *      xt_connmark - Netfilter module to operate on connection marks
   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@medozas.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
  24 #include <linux/module.h>
  25 #include <linux/skbuff.h>
  26 #include <net/netfilter/nf_conntrack.h>
  27 #include <net/netfilter/nf_conntrack_ecache.h>
  28 #include <linux/netfilter/x_tables.h>
  29 #include <linux/netfilter/xt_connmark.h>
  30
  31 MODULE_AUTHOR("Henrik Nordstrom <hno@marasystems.com>");
  32 MODULE_DESCRIPTION("Xtables: connection mark operations");
  33 MODULE_LICENSE("GPL");
  34 MODULE_ALIAS("ipt_CONNMARK");
  35 MODULE_ALIAS("ip6t_CONNMARK");
  36 MODULE_ALIAS("ipt_connmark");
  37 MODULE_ALIAS("ip6t_connmark");
  38
  39 static unsigned int
  40 connmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
  41 {
  42         const struct xt_connmark_tginfo1 *info = par->targinfo;
  43         enum ip_conntrack_info ctinfo;
  44         struct nf_conn *ct;
  45         u_int32_t newmark;
  46
  47         ct = nf_ct_get(skb, &ctinfo);
  48         if (ct == NULL)
  49                 return XT_CONTINUE;
  50
  51         switch (info->mode) {
  52         case XT_CONNMARK_SET:
  53                 newmark = (ct->mark & ~info->ctmask) ^ info->ctmark;
  54                 if (ct->mark != newmark) {
  55                         ct->mark = newmark;
  56                         nf_conntrack_event_cache(IPCT_MARK, ct);
  57                 }
  58                 break;
  59         case XT_CONNMARK_SAVE:
  60                 newmark = (ct->mark & ~info->ctmask) ^
  61                           (skb->mark & info->nfmask);
  62                 if (ct->mark != newmark) {
  63                         ct->mark = newmark;
  64                         nf_conntrack_event_cache(IPCT_MARK, ct);
  65                 }
  66                 break;
  67         case XT_CONNMARK_RESTORE:
  68                 newmark = (skb->mark & ~info->nfmask) ^
  69                           (ct->mark & info->ctmask);
  70                 skb->mark = newmark;
  71                 break;
  72         }
  73
  74         return XT_CONTINUE;
  75 }
  76
  77 static int connmark_tg_check(const struct xt_tgchk_param *par)
  78 {
  79         int ret;
  80
  81         ret = nf_ct_l3proto_try_module_get(par->family);
  82         if (ret < 0)
  83                 pr_info("cannot load conntrack support for proto=%u\n",
  84                         par->family);
  85         return ret;
  86 }
  87
  88 static void connmark_tg_destroy(const struct xt_tgdtor_param *par)
  89 {
  90         nf_ct_l3proto_module_put(par->family);
  91 }
  92
  93 static bool
  94 connmark_mt(const struct sk_buff *skb, struct xt_action_param *par)
  95 {
  96         const struct xt_connmark_mtinfo1 *info = par->matchinfo;
  97         enum ip_conntrack_info ctinfo;
  98         const struct nf_conn *ct;
  99
 100         ct = nf_ct_get(skb, &ctinfo);
 101         if (ct == NULL)
 102                 return false;
 103
 104         return ((ct->mark & info->mask) == info->mark) ^ info->invert;
 105 }
 106
 107 static int connmark_mt_check(const struct xt_mtchk_param *par)
 108 {
 109         int ret;
 110
 111         ret = nf_ct_l3proto_try_module_get(par->family);
 112         if (ret < 0)
 113                 pr_info("cannot load conntrack support for proto=%u\n",
 114                         par->family);
 115         return ret;
 116 }
 117
 118 static void connmark_mt_destroy(const struct xt_mtdtor_param *par)
 119 {
 120         nf_ct_l3proto_module_put(par->family);
 121 }
 122
 123 static struct xt_target connmark_tg_reg __read_mostly = {
 124         .name           = "CONNMARK",
 125         .revision       = 1,
 126         .family         = NFPROTO_UNSPEC,
 127         .checkentry     = connmark_tg_check,
 128         .target         = connmark_tg,
 129         .targetsize     = sizeof(struct xt_connmark_tginfo1),
 130         .destroy        = connmark_tg_destroy,
 131         .me             = THIS_MODULE,
 132 };
 133
 134 static struct xt_match connmark_mt_reg __read_mostly = {
 135         .name           = "connmark",
 136         .revision       = 1,
 137         .family         = NFPROTO_UNSPEC,
 138         .checkentry     = connmark_mt_check,
 139         .match          = connmark_mt,
 140         .matchsize      = sizeof(struct xt_connmark_mtinfo1),
 141         .destroy        = connmark_mt_destroy,
 142         .me             = THIS_MODULE,
 143 };
 144
 145 static int __init connmark_mt_init(void)
 146 {
 147         int ret;
 148
 149         ret = xt_register_target(&connmark_tg_reg);
 150         if (ret < 0)
 151                 return ret;
 152         ret = xt_register_match(&connmark_mt_reg);
 153         if (ret < 0) {
 154                 xt_unregister_target(&connmark_tg_reg);
 155                 return ret;
 156         }
 157         return 0;
 158 }
 159
 160 static void __exit connmark_mt_exit(void)
 161 {
 162         xt_unregister_match(&connmark_mt_reg);
 163         xt_unregister_target(&connmark_tg_reg);
 164 }
 165
 166 module_init(connmark_mt_init);
 167 module_exit(connmark_mt_exit);