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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 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
 116 connmark_tg_check_v0(const char *tablename, const void *entry,
 117                      const struct xt_target *target, void *targinfo,
 118                      unsigned int hook_mask)
 119 {
 120         const struct xt_connmark_target_info *matchinfo = targinfo;
 121
 122         if (matchinfo->mode == XT_CONNMARK_RESTORE) {
 123                 if (strcmp(tablename, "mangle") != 0) {
 124                         printk(KERN_WARNING "CONNMARK: restore can only be "
 125                                "called from \"mangle\" table, not \"%s\"\n",
 126                                tablename);
 127                         return false;
 128                 }
 129         }
 130         if (matchinfo->mark > 0xffffffff || matchinfo->mask > 0xffffffff) {
 131                 printk(KERN_WARNING "CONNMARK: Only supports 32bit mark\n");
 132                 return false;
 133         }
 134         if (nf_ct_l3proto_try_module_get(target->family) < 0) {
 135                 printk(KERN_WARNING "can't load conntrack support for "
 136                                     "proto=%u\n", target->family);
 137                 return false;
 138         }
 139         return true;
 140 }
 141
 142 static bool
 143 connmark_tg_check(const char *tablename, const void *entry,
 144                   const struct xt_target *target, void *targinfo,
 145                   unsigned int hook_mask)
 146 {
 147         if (nf_ct_l3proto_try_module_get(target->family) < 0) {
 148                 printk(KERN_WARNING "cannot load conntrack support for "
 149                        "proto=%u\n", target->family);
 150                 return false;
 151         }
 152         return true;
 153 }
 154
 155 static void
 156 connmark_tg_destroy(const struct xt_target *target, void *targinfo)
 157 {
 158         nf_ct_l3proto_module_put(target->family);
 159 }
 160
 161 #ifdef CONFIG_COMPAT
 162 struct compat_xt_connmark_target_info {
 163         compat_ulong_t  mark, mask;
 164         u_int8_t        mode;
 165         u_int8_t        __pad1;
 166         u_int16_t       __pad2;
 167 };
 168
 169 static void connmark_tg_compat_from_user_v0(void *dst, void *src)
 170 {
 171         const struct compat_xt_connmark_target_info *cm = src;
 172         struct xt_connmark_target_info m = {
 173                 .mark   = cm->mark,
 174                 .mask   = cm->mask,
 175                 .mode   = cm->mode,
 176         };
 177         memcpy(dst, &m, sizeof(m));
 178 }
 179
 180 static int connmark_tg_compat_to_user_v0(void __user *dst, void *src)
 181 {
 182         const struct xt_connmark_target_info *m = src;
 183         struct compat_xt_connmark_target_info cm = {
 184                 .mark   = m->mark,
 185                 .mask   = m->mask,
 186                 .mode   = m->mode,
 187         };
 188         return copy_to_user(dst, &cm, sizeof(cm)) ? -EFAULT : 0;
 189 }
 190 #endif /* CONFIG_COMPAT */
 191
 192 static struct xt_target connmark_tg_reg[] __read_mostly = {
 193         {
 194                 .name           = "CONNMARK",
 195                 .revision       = 0,
 196                 .family         = NFPROTO_IPV4,
 197                 .checkentry     = connmark_tg_check_v0,
 198                 .destroy        = connmark_tg_destroy,
 199                 .target         = connmark_tg_v0,
 200                 .targetsize     = sizeof(struct xt_connmark_target_info),
 201 #ifdef CONFIG_COMPAT
 202                 .compatsize     = sizeof(struct compat_xt_connmark_target_info),
 203                 .compat_from_user = connmark_tg_compat_from_user_v0,
 204                 .compat_to_user = connmark_tg_compat_to_user_v0,
 205 #endif
 206                 .me             = THIS_MODULE
 207         },
 208         {
 209                 .name           = "CONNMARK",
 210                 .revision       = 0,
 211                 .family         = NFPROTO_IPV6,
 212                 .checkentry     = connmark_tg_check_v0,
 213                 .destroy        = connmark_tg_destroy,
 214                 .target         = connmark_tg_v0,
 215                 .targetsize     = sizeof(struct xt_connmark_target_info),
 216 #ifdef CONFIG_COMPAT
 217                 .compatsize     = sizeof(struct compat_xt_connmark_target_info),
 218                 .compat_from_user = connmark_tg_compat_from_user_v0,
 219                 .compat_to_user = connmark_tg_compat_to_user_v0,
 220 #endif
 221                 .me             = THIS_MODULE
 222         },
 223         {
 224                 .name           = "CONNMARK",
 225                 .revision       = 1,
 226                 .family         = NFPROTO_IPV4,
 227                 .checkentry     = connmark_tg_check,
 228                 .target         = connmark_tg,
 229                 .targetsize     = sizeof(struct xt_connmark_tginfo1),
 230                 .destroy        = connmark_tg_destroy,
 231                 .me             = THIS_MODULE,
 232         },
 233         {
 234                 .name           = "CONNMARK",
 235                 .revision       = 1,
 236                 .family         = NFPROTO_IPV6,
 237                 .checkentry     = connmark_tg_check,
 238                 .target         = connmark_tg,
 239                 .targetsize     = sizeof(struct xt_connmark_tginfo1),
 240                 .destroy        = connmark_tg_destroy,
 241                 .me             = THIS_MODULE,
 242         },
 243 };
 244
 245 static int __init connmark_tg_init(void)
 246 {
 247         return xt_register_targets(connmark_tg_reg,
 248                ARRAY_SIZE(connmark_tg_reg));
 249 }
 250
 251 static void __exit connmark_tg_exit(void)
 252 {
 253         xt_unregister_targets(connmark_tg_reg, ARRAY_SIZE(connmark_tg_reg));
 254 }
 255
 256 module_init(connmark_tg_init);
 257 module_exit(connmark_tg_exit);