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   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 net_device *in,
  40                const struct net_device *out, unsigned int hooknum,
  41                const struct xt_target *target, const void *targinfo)
  42 {
  43         const struct xt_connmark_target_info *markinfo = targinfo;
  44         struct nf_conn *ct;
  45         enum ip_conntrack_info ctinfo;
  46         u_int32_t diff;
  47         u_int32_t mark;
  48         u_int32_t newmark;
  49
  50         ct = nf_ct_get(skb, &ctinfo);
  51         if (ct) {
  52                 switch(markinfo->mode) {
  53                 case XT_CONNMARK_SET:
  54                         newmark = (ct->mark & ~markinfo->mask) | markinfo->mark;
  55                         if (newmark != ct->mark) {
  56                                 ct->mark = newmark;
  57                                 nf_conntrack_event_cache(IPCT_MARK, skb);
  58                         }
  59                         break;
  60                 case XT_CONNMARK_SAVE:
  61                         newmark = (ct->mark & ~markinfo->mask) |
  62                                   (skb->mark & markinfo->mask);
  63                         if (ct->mark != newmark) {
  64                                 ct->mark = newmark;
  65                                 nf_conntrack_event_cache(IPCT_MARK, skb);
  66                         }
  67                         break;
  68                 case XT_CONNMARK_RESTORE:
  69                         mark = skb->mark;
  70                         diff = (ct->mark ^ mark) & markinfo->mask;
  71                         skb->mark = mark ^ diff;
  72                         break;
  73                 }
  74         }
  75
  76         return XT_CONTINUE;
  77 }
  78
  79 static unsigned int
  80 connmark_tg(struct sk_buff *skb, const struct net_device *in,
  81             const struct net_device *out, unsigned int hooknum,
  82             const struct xt_target *target, const void *targinfo)
  83 {
  84         const struct xt_connmark_tginfo1 *info = targinfo;
  85         enum ip_conntrack_info ctinfo;
  86         struct nf_conn *ct;
  87         u_int32_t newmark;
  88
  89         ct = nf_ct_get(skb, &ctinfo);
  90         if (ct == NULL)
  91                 return XT_CONTINUE;
  92
  93         switch (info->mode) {
  94         case XT_CONNMARK_SET:
  95                 newmark = (ct->mark & ~info->ctmask) ^ info->ctmark;
  96                 if (ct->mark != newmark) {
  97                         ct->mark = newmark;
  98                         nf_conntrack_event_cache(IPCT_MARK, skb);
  99                 }
 100                 break;
 101         case XT_CONNMARK_SAVE:
 102                 newmark = (ct->mark & ~info->ctmask) ^
 103                           (skb->mark & info->nfmask);
 104                 if (ct->mark != newmark) {
 105                         ct->mark = newmark;
 106                         nf_conntrack_event_cache(IPCT_MARK, skb);
 107                 }
 108                 break;
 109         case XT_CONNMARK_RESTORE:
 110                 newmark = (skb->mark & ~info->nfmask) ^
 111                           (ct->mark & info->ctmask);
 112                 skb->mark = newmark;
 113                 break;
 114         }
 115
 116         return XT_CONTINUE;
 117 }
 118
 119 static bool
 120 connmark_tg_check_v0(const char *tablename, const void *entry,
 121                      const struct xt_target *target, void *targinfo,
 122                      unsigned int hook_mask)
 123 {
 124         const struct xt_connmark_target_info *matchinfo = targinfo;
 125
 126         if (matchinfo->mode == XT_CONNMARK_RESTORE) {
 127                 if (strcmp(tablename, "mangle") != 0) {
 128                         printk(KERN_WARNING "CONNMARK: restore can only be "
 129                                "called from \"mangle\" table, not \"%s\"\n",
 130                                tablename);
 131                         return false;
 132                 }
 133         }
 134         if (matchinfo->mark > 0xffffffff || matchinfo->mask > 0xffffffff) {
 135                 printk(KERN_WARNING "CONNMARK: Only supports 32bit mark\n");
 136                 return false;
 137         }
 138         if (nf_ct_l3proto_try_module_get(target->family) < 0) {
 139                 printk(KERN_WARNING "can't load conntrack support for "
 140                                     "proto=%u\n", target->family);
 141                 return false;
 142         }
 143         return true;
 144 }
 145
 146 static bool
 147 connmark_tg_check(const char *tablename, const void *entry,
 148                   const struct xt_target *target, void *targinfo,
 149                   unsigned int hook_mask)
 150 {
 151         if (nf_ct_l3proto_try_module_get(target->family) < 0) {
 152                 printk(KERN_WARNING "cannot load conntrack support for "
 153                        "proto=%u\n", target->family);
 154                 return false;
 155         }
 156         return true;
 157 }
 158
 159 static void
 160 connmark_tg_destroy(const struct xt_target *target, void *targinfo)
 161 {
 162         nf_ct_l3proto_module_put(target->family);
 163 }
 164
 165 #ifdef CONFIG_COMPAT
 166 struct compat_xt_connmark_target_info {
 167         compat_ulong_t  mark, mask;
 168         u_int8_t        mode;
 169         u_int8_t        __pad1;
 170         u_int16_t       __pad2;
 171 };
 172
 173 static void connmark_tg_compat_from_user_v0(void *dst, void *src)
 174 {
 175         const struct compat_xt_connmark_target_info *cm = src;
 176         struct xt_connmark_target_info m = {
 177                 .mark   = cm->mark,
 178                 .mask   = cm->mask,
 179                 .mode   = cm->mode,
 180         };
 181         memcpy(dst, &m, sizeof(m));
 182 }
 183
 184 static int connmark_tg_compat_to_user_v0(void __user *dst, void *src)
 185 {
 186         const struct xt_connmark_target_info *m = src;
 187         struct compat_xt_connmark_target_info cm = {
 188                 .mark   = m->mark,
 189                 .mask   = m->mask,
 190                 .mode   = m->mode,
 191         };
 192         return copy_to_user(dst, &cm, sizeof(cm)) ? -EFAULT : 0;
 193 }
 194 #endif /* CONFIG_COMPAT */
 195
 196 static struct xt_target connmark_tg_reg[] __read_mostly = {
 197         {
 198                 .name           = "CONNMARK",
 199                 .revision       = 0,
 200                 .family         = AF_INET,
 201                 .checkentry     = connmark_tg_check_v0,
 202                 .destroy        = connmark_tg_destroy,
 203                 .target         = connmark_tg_v0,
 204                 .targetsize     = sizeof(struct xt_connmark_target_info),
 205 #ifdef CONFIG_COMPAT
 206                 .compatsize     = sizeof(struct compat_xt_connmark_target_info),
 207                 .compat_from_user = connmark_tg_compat_from_user_v0,
 208                 .compat_to_user = connmark_tg_compat_to_user_v0,
 209 #endif
 210                 .me             = THIS_MODULE
 211         },
 212         {
 213                 .name           = "CONNMARK",
 214                 .revision       = 0,
 215                 .family         = AF_INET6,
 216                 .checkentry     = connmark_tg_check_v0,
 217                 .destroy        = connmark_tg_destroy,
 218                 .target         = connmark_tg_v0,
 219                 .targetsize     = sizeof(struct xt_connmark_target_info),
 220 #ifdef CONFIG_COMPAT
 221                 .compatsize     = sizeof(struct compat_xt_connmark_target_info),
 222                 .compat_from_user = connmark_tg_compat_from_user_v0,
 223                 .compat_to_user = connmark_tg_compat_to_user_v0,
 224 #endif
 225                 .me             = THIS_MODULE
 226         },
 227         {
 228                 .name           = "CONNMARK",
 229                 .revision       = 1,
 230                 .family         = AF_INET,
 231                 .checkentry     = connmark_tg_check,
 232                 .target         = connmark_tg,
 233                 .targetsize     = sizeof(struct xt_connmark_tginfo1),
 234                 .destroy        = connmark_tg_destroy,
 235                 .me             = THIS_MODULE,
 236         },
 237         {
 238                 .name           = "CONNMARK",
 239                 .revision       = 1,
 240                 .family         = AF_INET6,
 241                 .checkentry     = connmark_tg_check,
 242                 .target         = connmark_tg,
 243                 .targetsize     = sizeof(struct xt_connmark_tginfo1),
 244                 .destroy        = connmark_tg_destroy,
 245                 .me             = THIS_MODULE,
 246         },
 247 };
 248
 249 static int __init connmark_tg_init(void)
 250 {
 251         return xt_register_targets(connmark_tg_reg,
 252                ARRAY_SIZE(connmark_tg_reg));
 253 }
 254
 255 static void __exit connmark_tg_exit(void)
 256 {
 257         xt_unregister_targets(connmark_tg_reg, ARRAY_SIZE(connmark_tg_reg));
 258 }
 259
 260 module_init(connmark_tg_init);
 261 module_exit(connmark_tg_exit);