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_shift(struct sk_buff *skb, const struct xt_connmark_tginfo2 *info)
  40 {
  41         enum ip_conntrack_info ctinfo;
  42         u_int32_t new_targetmark;
  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 (info->shift_dir == D_SHIFT_RIGHT)
  54                         newmark >>= info->shift_bits;
  55                 else
  56                         newmark <<= info->shift_bits;
  57
  58                 if (ct->mark != newmark) {
  59                         ct->mark = newmark;
  60                         nf_conntrack_event_cache(IPCT_MARK, ct);
  61                 }
  62                 break;
  63         case XT_CONNMARK_SAVE:
  64                 new_targetmark = (skb->mark & info->nfmask);
  65                 if (info->shift_dir == D_SHIFT_RIGHT)
  66                         new_targetmark >>= info->shift_bits;
  67                 else
  68                         new_targetmark <<= info->shift_bits;
  69
  70                 newmark = (ct->mark & ~info->ctmask) ^
  71                           new_targetmark;
  72                 if (ct->mark != newmark) {
  73                         ct->mark = newmark;
  74                         nf_conntrack_event_cache(IPCT_MARK, ct);
  75                 }
  76                 break;
  77         case XT_CONNMARK_RESTORE:
  78                 new_targetmark = (ct->mark & info->ctmask);
  79                 if (info->shift_dir == D_SHIFT_RIGHT)
  80                         new_targetmark >>= info->shift_bits;
  81                 else
  82                         new_targetmark <<= info->shift_bits;
  83
  84                 newmark = (skb->mark & ~info->nfmask) ^
  85                           new_targetmark;
  86                 skb->mark = newmark;
  87                 break;
  88         }
  89         return XT_CONTINUE;
  90 }
  91
  92 static unsigned int
  93 connmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
  94 {
  95         const struct xt_connmark_tginfo1 *info = par->targinfo;
  96         const struct xt_connmark_tginfo2 info2 = {
  97                 .ctmark = info->ctmark,
  98                 .ctmask = info->ctmask,
  99                 .nfmask = info->nfmask,
 100                 .mode   = info->mode,
 101         };
 102
 103         return connmark_tg_shift(skb, &info2);
 104 }
 105
 106 static unsigned int
 107 connmark_tg_v2(struct sk_buff *skb, const struct xt_action_param *par)
 108 {
 109         const struct xt_connmark_tginfo2 *info = par->targinfo;
 110
 111         return connmark_tg_shift(skb, info);
 112 }
 113
 114 static int connmark_tg_check(const struct xt_tgchk_param *par)
 115 {
 116         int ret;
 117
 118         ret = nf_ct_netns_get(par->net, par->family);
 119         if (ret < 0)
 120                 pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
 121                                     par->family);
 122         return ret;
 123 }
 124
 125 static void connmark_tg_destroy(const struct xt_tgdtor_param *par)
 126 {
 127         nf_ct_netns_put(par->net, par->family);
 128 }
 129
 130 static bool
 131 connmark_mt(const struct sk_buff *skb, struct xt_action_param *par)
 132 {
 133         const struct xt_connmark_mtinfo1 *info = par->matchinfo;
 134         enum ip_conntrack_info ctinfo;
 135         const struct nf_conn *ct;
 136
 137         ct = nf_ct_get(skb, &ctinfo);
 138         if (ct == NULL)
 139                 return false;
 140
 141         return ((ct->mark & info->mask) == info->mark) ^ info->invert;
 142 }
 143
 144 static int connmark_mt_check(const struct xt_mtchk_param *par)
 145 {
 146         int ret;
 147
 148         ret = nf_ct_netns_get(par->net, par->family);
 149         if (ret < 0)
 150                 pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
 151                                     par->family);
 152         return ret;
 153 }
 154
 155 static void connmark_mt_destroy(const struct xt_mtdtor_param *par)
 156 {
 157         nf_ct_netns_put(par->net, par->family);
 158 }
 159
 160 static struct xt_target connmark_tg_reg[] __read_mostly = {
 161         {
 162                 .name           = "CONNMARK",
 163                 .revision       = 1,
 164                 .family         = NFPROTO_UNSPEC,
 165                 .checkentry     = connmark_tg_check,
 166                 .target         = connmark_tg,
 167                 .targetsize     = sizeof(struct xt_connmark_tginfo1),
 168                 .destroy        = connmark_tg_destroy,
 169                 .me             = THIS_MODULE,
 170         },
 171         {
 172                 .name           = "CONNMARK",
 173                 .revision       = 2,
 174                 .family         = NFPROTO_UNSPEC,
 175                 .checkentry     = connmark_tg_check,
 176                 .target         = connmark_tg_v2,
 177                 .targetsize     = sizeof(struct xt_connmark_tginfo2),
 178                 .destroy        = connmark_tg_destroy,
 179                 .me             = THIS_MODULE,
 180         }
 181 };
 182
 183 static struct xt_match connmark_mt_reg __read_mostly = {
 184         .name           = "connmark",
 185         .revision       = 1,
 186         .family         = NFPROTO_UNSPEC,
 187         .checkentry     = connmark_mt_check,
 188         .match          = connmark_mt,
 189         .matchsize      = sizeof(struct xt_connmark_mtinfo1),
 190         .destroy        = connmark_mt_destroy,
 191         .me             = THIS_MODULE,
 192 };
 193
 194 static int __init connmark_mt_init(void)
 195 {
 196         int ret;
 197
 198         ret = xt_register_targets(connmark_tg_reg,
 199                                   ARRAY_SIZE(connmark_tg_reg));
 200         if (ret < 0)
 201                 return ret;
 202         ret = xt_register_match(&connmark_mt_reg);
 203         if (ret < 0) {
 204                 xt_unregister_targets(connmark_tg_reg,
 205                                       ARRAY_SIZE(connmark_tg_reg));
 206                 return ret;
 207         }
 208         return 0;
 209 }
 210
 211 static void __exit connmark_mt_exit(void)
 212 {
 213         xt_unregister_match(&connmark_mt_reg);
 214         xt_unregister_targets(connmark_tg_reg, ARRAY_SIZE(connmark_tg_reg));
 215 }
 216
 217 module_init(connmark_mt_init);
 218 module_exit(connmark_mt_exit);