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, see <http://www.gnu.org/licenses/>.
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/skbuff.h>
  25 #include <net/netfilter/nf_conntrack.h>
  26 #include <net/netfilter/nf_conntrack_ecache.h>
  27 #include <linux/netfilter/x_tables.h>
  28 #include <linux/netfilter/xt_connmark.h>
  29
  30 MODULE_AUTHOR("Henrik Nordstrom <hno@marasystems.com>");
  31 MODULE_DESCRIPTION("Xtables: connection mark operations");
  32 MODULE_LICENSE("GPL");
  33 MODULE_ALIAS("ipt_CONNMARK");
  34 MODULE_ALIAS("ip6t_CONNMARK");
  35 MODULE_ALIAS("ipt_connmark");
  36 MODULE_ALIAS("ip6t_connmark");
  37
  38 static unsigned int
  39 connmark_tg(struct sk_buff *skb, const struct xt_action_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 int connmark_tg_check(const struct xt_tgchk_param *par)
  77 {
  78         int ret;
  79
  80         ret = nf_ct_l3proto_try_module_get(par->family);
  81         if (ret < 0)
  82                 pr_info("cannot load conntrack support for proto=%u\n",
  83                         par->family);
  84         return ret;
  85 }
  86
  87 static void connmark_tg_destroy(const struct xt_tgdtor_param *par)
  88 {
  89         nf_ct_l3proto_module_put(par->family);
  90 }
  91
  92 static bool
  93 connmark_mt(const struct sk_buff *skb, struct xt_action_param *par)
  94 {
  95         const struct xt_connmark_mtinfo1 *info = par->matchinfo;
  96         enum ip_conntrack_info ctinfo;
  97         const struct nf_conn *ct;
  98
  99         ct = nf_ct_get(skb, &ctinfo);
 100         if (ct == NULL)
 101                 return false;
 102
 103         return ((ct->mark & info->mask) == info->mark) ^ info->invert;
 104 }
 105
 106 static int connmark_mt_check(const struct xt_mtchk_param *par)
 107 {
 108         int ret;
 109
 110         ret = nf_ct_l3proto_try_module_get(par->family);
 111         if (ret < 0)
 112                 pr_info("cannot load conntrack support for proto=%u\n",
 113                         par->family);
 114         return ret;
 115 }
 116
 117 static void connmark_mt_destroy(const struct xt_mtdtor_param *par)
 118 {
 119         nf_ct_l3proto_module_put(par->family);
 120 }
 121
 122 static struct xt_target connmark_tg_reg __read_mostly = {
 123         .name           = "CONNMARK",
 124         .revision       = 1,
 125         .family         = NFPROTO_UNSPEC,
 126         .checkentry     = connmark_tg_check,
 127         .target         = connmark_tg,
 128         .targetsize     = sizeof(struct xt_connmark_tginfo1),
 129         .destroy        = connmark_tg_destroy,
 130         .me             = THIS_MODULE,
 131 };
 132
 133 static struct xt_match connmark_mt_reg __read_mostly = {
 134         .name           = "connmark",
 135         .revision       = 1,
 136         .family         = NFPROTO_UNSPEC,
 137         .checkentry     = connmark_mt_check,
 138         .match          = connmark_mt,
 139         .matchsize      = sizeof(struct xt_connmark_mtinfo1),
 140         .destroy        = connmark_mt_destroy,
 141         .me             = THIS_MODULE,
 142 };
 143
 144 static int __init connmark_mt_init(void)
 145 {
 146         int ret;
 147
 148         ret = xt_register_target(&connmark_tg_reg);
 149         if (ret < 0)
 150                 return ret;
 151         ret = xt_register_match(&connmark_mt_reg);
 152         if (ret < 0) {
 153                 xt_unregister_target(&connmark_tg_reg);
 154                 return ret;
 155         }
 156         return 0;
 157 }
 158
 159 static void __exit connmark_mt_exit(void)
 160 {
 161         xt_unregister_match(&connmark_mt_reg);
 162         xt_unregister_target(&connmark_tg_reg);
 163 }
 164
 165 module_init(connmark_mt_init);
 166 module_exit(connmark_mt_exit);