net/netfilter/xt_CONNMARK.c

   1 /* This kernel module is used to modify the connection mark values, or
   2  * to optionally restore the skb nfmark from the connection mark
   3  *
   4  * Copyright (C) 2002,2004 MARA Systems AB <http://www.marasystems.com>
   5  * by Henrik Nordstrom <hno@marasystems.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  */
  21 #include <linux/module.h>
  22 #include <linux/skbuff.h>
  23 #include <linux/ip.h>
  24 #include <net/checksum.h>
  25
  26 MODULE_AUTHOR("Henrik Nordstrom <hno@marasystems.com>");
  27 MODULE_DESCRIPTION("IP tables CONNMARK matching module");
  28 MODULE_LICENSE("GPL");
  29 MODULE_ALIAS("ipt_CONNMARK");
  30 MODULE_ALIAS("ip6t_CONNMARK");
  31
  32 #include <linux/netfilter/x_tables.h>
  33 #include <linux/netfilter/xt_CONNMARK.h>
  34 #include <net/netfilter/nf_conntrack_ecache.h>
  35
  36 static unsigned int
  37 connmark_tg(struct sk_buff *skb, const struct net_device *in,
  38             const struct net_device *out, unsigned int hooknum,
  39             const struct xt_target *target, const void *targinfo)
  40 {
  41         const struct xt_connmark_target_info *markinfo = 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, skb);
  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, skb);
  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 bool
  78 connmark_tg_check(const char *tablename, const void *entry,
  79                   const struct xt_target *target, void *targinfo,
  80                   unsigned int hook_mask)
  81 {
  82         const struct xt_connmark_target_info *matchinfo = targinfo;
  83
  84         if (matchinfo->mode == XT_CONNMARK_RESTORE) {
  85                 if (strcmp(tablename, "mangle") != 0) {
  86                         printk(KERN_WARNING "CONNMARK: restore can only be "
  87                                "called from \"mangle\" table, not \"%s\"\n",
  88                                tablename);
  89                         return false;
  90                 }
  91         }
  92         if (matchinfo->mark > 0xffffffff || matchinfo->mask > 0xffffffff) {
  93                 printk(KERN_WARNING "CONNMARK: Only supports 32bit mark\n");
  94                 return false;
  95         }
  96         if (nf_ct_l3proto_try_module_get(target->family) < 0) {
  97                 printk(KERN_WARNING "can't load conntrack support for "
  98                                     "proto=%d\n", target->family);
  99                 return false;
 100         }
 101         return true;
 102 }
 103
 104 static void
 105 connmark_tg_destroy(const struct xt_target *target, void *targinfo)
 106 {
 107         nf_ct_l3proto_module_put(target->family);
 108 }
 109
 110 #ifdef CONFIG_COMPAT
 111 struct compat_xt_connmark_target_info {
 112         compat_ulong_t  mark, mask;
 113         u_int8_t        mode;
 114         u_int8_t        __pad1;
 115         u_int16_t       __pad2;
 116 };
 117
 118 static void connmark_tg_compat_from_user(void *dst, void *src)
 119 {
 120         const struct compat_xt_connmark_target_info *cm = src;
 121         struct xt_connmark_target_info m = {
 122                 .mark   = cm->mark,
 123                 .mask   = cm->mask,
 124                 .mode   = cm->mode,
 125         };
 126         memcpy(dst, &m, sizeof(m));
 127 }
 128
 129 static int connmark_tg_compat_to_user(void __user *dst, void *src)
 130 {
 131         const struct xt_connmark_target_info *m = src;
 132         struct compat_xt_connmark_target_info cm = {
 133                 .mark   = m->mark,
 134                 .mask   = m->mask,
 135                 .mode   = m->mode,
 136         };
 137         return copy_to_user(dst, &cm, sizeof(cm)) ? -EFAULT : 0;
 138 }
 139 #endif /* CONFIG_COMPAT */
 140
 141 static struct xt_target connmark_tg_reg[] __read_mostly = {
 142         {
 143                 .name           = "CONNMARK",
 144                 .family         = AF_INET,
 145                 .checkentry     = connmark_tg_check,
 146                 .destroy        = connmark_tg_destroy,
 147                 .target         = connmark_tg,
 148                 .targetsize     = sizeof(struct xt_connmark_target_info),
 149 #ifdef CONFIG_COMPAT
 150                 .compatsize     = sizeof(struct compat_xt_connmark_target_info),
 151                 .compat_from_user = connmark_tg_compat_from_user,
 152                 .compat_to_user = connmark_tg_compat_to_user,
 153 #endif
 154                 .me             = THIS_MODULE
 155         },
 156         {
 157                 .name           = "CONNMARK",
 158                 .family         = AF_INET6,
 159                 .checkentry     = connmark_tg_check,
 160                 .destroy        = connmark_tg_destroy,
 161                 .target         = connmark_tg,
 162                 .targetsize     = sizeof(struct xt_connmark_target_info),
 163 #ifdef CONFIG_COMPAT
 164                 .compatsize     = sizeof(struct compat_xt_connmark_target_info),
 165                 .compat_from_user = connmark_tg_compat_from_user,
 166                 .compat_to_user = connmark_tg_compat_to_user,
 167 #endif
 168                 .me             = THIS_MODULE
 169         },
 170 };
 171
 172 static int __init connmark_tg_init(void)
 173 {
 174         return xt_register_targets(connmark_tg_reg,
 175                ARRAY_SIZE(connmark_tg_reg));
 176 }
 177
 178 static void __exit connmark_tg_exit(void)
 179 {
 180         xt_unregister_targets(connmark_tg_reg, ARRAY_SIZE(connmark_tg_reg));
 181 }
 182
 183 module_init(connmark_tg_init);
 184 module_exit(connmark_tg_exit);