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,
  40                 const struct xt_connmark_tginfo1 *info,
  41                 u8 shift_bits, u8 shift_dir)
  42 {
  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 (shift_dir == D_SHIFT_RIGHT)
  55                         newmark >>= shift_bits;
  56                 else
  57                         newmark <<= shift_bits;
  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                 newmark = (ct->mark & ~info->ctmask) ^
  65                           (skb->mark & info->nfmask);
  66                 if (shift_dir == D_SHIFT_RIGHT)
  67                         newmark >>= shift_bits;
  68                 else
  69                         newmark <<= shift_bits;
  70                 if (ct->mark != newmark) {
  71                         ct->mark = newmark;
  72                         nf_conntrack_event_cache(IPCT_MARK, ct);
  73                 }
  74                 break;
  75         case XT_CONNMARK_RESTORE:
  76                 newmark = (skb->mark & ~info->nfmask) ^
  77                           (ct->mark & info->ctmask);
  78                 if (shift_dir == D_SHIFT_RIGHT)
  79                         newmark >>= shift_bits;
  80                 else
  81                         newmark <<= shift_bits;
  82                 skb->mark = newmark;
  83                 break;
  84         }
  85         return XT_CONTINUE;
  86 }
  87
  88 static unsigned int
  89 connmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
  90 {
  91         const struct xt_connmark_tginfo1 *info = par->targinfo;
  92
  93         return connmark_tg_shift(skb, info, 0, 0);
  94 }
  95
  96 static unsigned int
  97 connmark_tg_v2(struct sk_buff *skb, const struct xt_action_param *par)
  98 {
  99         const struct xt_connmark_tginfo2 *info = par->targinfo;
 100
 101         return connmark_tg_shift(skb, (const struct xt_connmark_tginfo1 *)info,
 102                                  info->shift_bits, info->shift_dir);
 103 }
 104
 105 static int connmark_tg_check(const struct xt_tgchk_param *par)
 106 {
 107         int ret;
 108
 109         ret = nf_ct_netns_get(par->net, par->family);
 110         if (ret < 0)
 111                 pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
 112                                     par->family);
 113         return ret;
 114 }
 115
 116 static void connmark_tg_destroy(const struct xt_tgdtor_param *par)
 117 {
 118         nf_ct_netns_put(par->net, par->family);
 119 }
 120
 121 static bool
 122 connmark_mt(const struct sk_buff *skb, struct xt_action_param *par)
 123 {
 124         const struct xt_connmark_mtinfo1 *info = par->matchinfo;
 125         enum ip_conntrack_info ctinfo;
 126         const struct nf_conn *ct;
 127
 128         ct = nf_ct_get(skb, &ctinfo);
 129         if (ct == NULL)
 130                 return false;
 131
 132         return ((ct->mark & info->mask) == info->mark) ^ info->invert;
 133 }
 134
 135 static int connmark_mt_check(const struct xt_mtchk_param *par)
 136 {
 137         int ret;
 138
 139         ret = nf_ct_netns_get(par->net, par->family);
 140         if (ret < 0)
 141                 pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
 142                                     par->family);
 143         return ret;
 144 }
 145
 146 static void connmark_mt_destroy(const struct xt_mtdtor_param *par)
 147 {
 148         nf_ct_netns_put(par->net, par->family);
 149 }
 150
 151 static struct xt_target connmark_tg_reg[] __read_mostly = {
 152         {
 153                 .name           = "CONNMARK",
 154                 .revision       = 1,
 155                 .family         = NFPROTO_UNSPEC,
 156                 .checkentry     = connmark_tg_check,
 157                 .target         = connmark_tg,
 158                 .targetsize     = sizeof(struct xt_connmark_tginfo1),
 159                 .destroy        = connmark_tg_destroy,
 160                 .me             = THIS_MODULE,
 161         },
 162         {
 163                 .name           = "CONNMARK",
 164                 .revision       = 2,
 165                 .family         = NFPROTO_UNSPEC,
 166                 .checkentry     = connmark_tg_check,
 167                 .target         = connmark_tg_v2,
 168                 .targetsize     = sizeof(struct xt_connmark_tginfo2),
 169                 .destroy        = connmark_tg_destroy,
 170                 .me             = THIS_MODULE,
 171         }
 172 };
 173
 174 static struct xt_match connmark_mt_reg __read_mostly = {
 175         .name           = "connmark",
 176         .revision       = 1,
 177         .family         = NFPROTO_UNSPEC,
 178         .checkentry     = connmark_mt_check,
 179         .match          = connmark_mt,
 180         .matchsize      = sizeof(struct xt_connmark_mtinfo1),
 181         .destroy        = connmark_mt_destroy,
 182         .me             = THIS_MODULE,
 183 };
 184
 185 static int __init connmark_mt_init(void)
 186 {
 187         int ret;
 188
 189         ret = xt_register_targets(connmark_tg_reg,
 190                                   ARRAY_SIZE(connmark_tg_reg));
 191         if (ret < 0)
 192                 return ret;
 193         ret = xt_register_match(&connmark_mt_reg);
 194         if (ret < 0) {
 195                 xt_unregister_targets(connmark_tg_reg,
 196                                       ARRAY_SIZE(connmark_tg_reg));
 197                 return ret;
 198         }
 199         return 0;
 200 }
 201
 202 static void __exit connmark_mt_exit(void)
 203 {
 204         xt_unregister_match(&connmark_mt_reg);
 205         xt_unregister_target(connmark_tg_reg);
 206 }
 207
 208 module_init(connmark_mt_init);
 209 module_exit(connmark_mt_exit);