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_v0(struct sk_buff *skb, const struct xt_target_param *par)
  40 {
  41         const struct xt_connmark_target_info *markinfo = par->targinfo;
  42         struct nf_conn *ct;
  43         enum ip_conntrack_info ctinfo;
  44         u_int32_t diff;
  45         u_int32_t mark;
  46         u_int32_t newmark;
  47
  48         ct = nf_ct_get(skb, &ctinfo);
  49         if (ct) {
  50                 switch(markinfo->mode) {
  51                 case XT_CONNMARK_SET:
  52                         newmark = (ct->mark & ~markinfo->mask) | markinfo->mark;
  53                         if (newmark != ct->mark) {
  54                                 ct->mark = newmark;
  55                                 nf_conntrack_event_cache(IPCT_MARK, ct);
  56                         }
  57                         break;
  58                 case XT_CONNMARK_SAVE:
  59                         newmark = (ct->mark & ~markinfo->mask) |
  60                                   (skb->mark & markinfo->mask);
  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                         mark = skb->mark;
  68                         diff = (ct->mark ^ mark) & markinfo->mask;
  69                         skb->mark = mark ^ diff;
  70                         break;
  71                 }
  72         }
  73
  74         return XT_CONTINUE;
  75 }
  76
  77 static unsigned int
  78 connmark_tg(struct sk_buff *skb, const struct xt_target_param *par)
  79 {
  80         const struct xt_connmark_tginfo1 *info = par->targinfo;
  81         enum ip_conntrack_info ctinfo;
  82         struct nf_conn *ct;
  83         u_int32_t newmark;
  84
  85         ct = nf_ct_get(skb, &ctinfo);
  86         if (ct == NULL)
  87                 return XT_CONTINUE;
  88
  89         switch (info->mode) {
  90         case XT_CONNMARK_SET:
  91                 newmark = (ct->mark & ~info->ctmask) ^ info->ctmark;
  92                 if (ct->mark != newmark) {
  93                         ct->mark = newmark;
  94                         nf_conntrack_event_cache(IPCT_MARK, ct);
  95                 }
  96                 break;
  97         case XT_CONNMARK_SAVE:
  98                 newmark = (ct->mark & ~info->ctmask) ^
  99                           (skb->mark & info->nfmask);
 100                 if (ct->mark != newmark) {
 101                         ct->mark = newmark;
 102                         nf_conntrack_event_cache(IPCT_MARK, ct);
 103                 }
 104                 break;
 105         case XT_CONNMARK_RESTORE:
 106                 newmark = (skb->mark & ~info->nfmask) ^
 107                           (ct->mark & info->ctmask);
 108                 skb->mark = newmark;
 109                 break;
 110         }
 111
 112         return XT_CONTINUE;
 113 }
 114
 115 static bool connmark_tg_check_v0(const struct xt_tgchk_param *par)
 116 {
 117         const struct xt_connmark_target_info *matchinfo = par->targinfo;
 118
 119         if (matchinfo->mode == XT_CONNMARK_RESTORE) {
 120                 if (strcmp(par->table, "mangle") != 0) {
 121                         printk(KERN_WARNING "CONNMARK: restore can only be "
 122                                "called from \"mangle\" table, not \"%s\"\n",
 123                                par->table);
 124                         return false;
 125                 }
 126         }
 127         if (matchinfo->mark > 0xffffffff || matchinfo->mask > 0xffffffff) {
 128                 printk(KERN_WARNING "CONNMARK: Only supports 32bit mark\n");
 129                 return false;
 130         }
 131         if (nf_ct_l3proto_try_module_get(par->family) < 0) {
 132                 printk(KERN_WARNING "can't load conntrack support for "
 133                                     "proto=%u\n", par->family);
 134                 return false;
 135         }
 136         return true;
 137 }
 138
 139 static bool connmark_tg_check(const struct xt_tgchk_param *par)
 140 {
 141         if (nf_ct_l3proto_try_module_get(par->family) < 0) {
 142                 printk(KERN_WARNING "cannot load conntrack support for "
 143                        "proto=%u\n", par->family);
 144                 return false;
 145         }
 146         return true;
 147 }
 148
 149 static void connmark_tg_destroy(const struct xt_tgdtor_param *par)
 150 {
 151         nf_ct_l3proto_module_put(par->family);
 152 }
 153
 154 #ifdef CONFIG_COMPAT
 155 struct compat_xt_connmark_target_info {
 156         compat_ulong_t  mark, mask;
 157         u_int8_t        mode;
 158         u_int8_t        __pad1;
 159         u_int16_t       __pad2;
 160 };
 161
 162 static void connmark_tg_compat_from_user_v0(void *dst, void *src)
 163 {
 164         const struct compat_xt_connmark_target_info *cm = src;
 165         struct xt_connmark_target_info m = {
 166                 .mark   = cm->mark,
 167                 .mask   = cm->mask,
 168                 .mode   = cm->mode,
 169         };
 170         memcpy(dst, &m, sizeof(m));
 171 }
 172
 173 static int connmark_tg_compat_to_user_v0(void __user *dst, void *src)
 174 {
 175         const struct xt_connmark_target_info *m = src;
 176         struct compat_xt_connmark_target_info cm = {
 177                 .mark   = m->mark,
 178                 .mask   = m->mask,
 179                 .mode   = m->mode,
 180         };
 181         return copy_to_user(dst, &cm, sizeof(cm)) ? -EFAULT : 0;
 182 }
 183 #endif /* CONFIG_COMPAT */
 184
 185 static struct xt_target connmark_tg_reg[] __read_mostly = {
 186         {
 187                 .name           = "CONNMARK",
 188                 .revision       = 0,
 189                 .family         = NFPROTO_UNSPEC,
 190                 .checkentry     = connmark_tg_check_v0,
 191                 .destroy        = connmark_tg_destroy,
 192                 .target         = connmark_tg_v0,
 193                 .targetsize     = sizeof(struct xt_connmark_target_info),
 194 #ifdef CONFIG_COMPAT
 195                 .compatsize     = sizeof(struct compat_xt_connmark_target_info),
 196                 .compat_from_user = connmark_tg_compat_from_user_v0,
 197                 .compat_to_user = connmark_tg_compat_to_user_v0,
 198 #endif
 199                 .me             = THIS_MODULE
 200         },
 201         {
 202                 .name           = "CONNMARK",
 203                 .revision       = 1,
 204                 .family         = NFPROTO_UNSPEC,
 205                 .checkentry     = connmark_tg_check,
 206                 .target         = connmark_tg,
 207                 .targetsize     = sizeof(struct xt_connmark_tginfo1),
 208                 .destroy        = connmark_tg_destroy,
 209                 .me             = THIS_MODULE,
 210         },
 211 };
 212
 213 static int __init connmark_tg_init(void)
 214 {
 215         return xt_register_targets(connmark_tg_reg,
 216                ARRAY_SIZE(connmark_tg_reg));
 217 }
 218
 219 static void __exit connmark_tg_exit(void)
 220 {
 221         xt_unregister_targets(connmark_tg_reg, ARRAY_SIZE(connmark_tg_reg));
 222 }
 223
 224 module_init(connmark_tg_init);
 225 module_exit(connmark_tg_exit);