err.no Git - linux-2.6/blob - 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@marasytems.com>");
  27 MODULE_DESCRIPTION("IP tables CONNMARK matching module");
  28 MODULE_LICENSE("GPL");
  29 MODULE_ALIAS("ipt_CONNMARK");
  30
  31 #include <linux/netfilter/x_tables.h>
  32 #include <linux/netfilter/xt_CONNMARK.h>
  33 #include <net/netfilter/nf_conntrack_compat.h>
  34
  35 static unsigned int
  36 target(struct sk_buff **pskb,
  37        const struct net_device *in,
  38        const struct net_device *out,
  39        unsigned int hooknum,
  40        const struct xt_target *target,
  41        const void *targinfo,
  42        void *userinfo)
  43 {
  44         const struct xt_connmark_target_info *markinfo = targinfo;
  45         u_int32_t diff;
  46         u_int32_t nfmark;
  47         u_int32_t newmark;
  48         u_int32_t ctinfo;
  49         u_int32_t *ctmark = nf_ct_get_mark(*pskb, &ctinfo);
  50
  51         if (ctmark) {
  52                 switch(markinfo->mode) {
  53                 case XT_CONNMARK_SET:
  54                         newmark = (*ctmark & ~markinfo->mask) | markinfo->mark;
  55                         if (newmark != *ctmark) {
  56                                 *ctmark = newmark;
  57 #ifdef CONFIG_IP_NF_CONNTRACK_EVENTS
  58                                 ip_conntrack_event_cache(IPCT_MARK, *pskb);
  59 #else
  60                                 nf_conntrack_event_cache(IPCT_MARK, *pskb);
  61 #endif
  62                 }
  63                         break;
  64                 case XT_CONNMARK_SAVE:
  65                         newmark = (*ctmark & ~markinfo->mask) |
  66                                   ((*pskb)->nfmark & markinfo->mask);
  67                         if (*ctmark != newmark) {
  68                                 *ctmark = newmark;
  69 #ifdef CONFIG_IP_NF_CONNTRACK_EVENTS
  70                                 ip_conntrack_event_cache(IPCT_MARK, *pskb);
  71 #else
  72                                 nf_conntrack_event_cache(IPCT_MARK, *pskb);
  73 #endif
  74                         }
  75                         break;
  76                 case XT_CONNMARK_RESTORE:
  77                         nfmark = (*pskb)->nfmark;
  78                         diff = (*ctmark ^ nfmark) & markinfo->mask;
  79                         if (diff != 0)
  80                                 (*pskb)->nfmark = nfmark ^ diff;
  81                         break;
  82                 }
  83         }
  84
  85         return XT_CONTINUE;
  86 }
  87
  88 static int
  89 checkentry(const char *tablename,
  90            const void *entry,
  91            const struct xt_target *target,
  92            void *targinfo,
  93            unsigned int targinfosize,
  94            unsigned int hook_mask)
  95 {
  96         struct xt_connmark_target_info *matchinfo = targinfo;
  97
  98         if (matchinfo->mode == XT_CONNMARK_RESTORE) {
  99                 if (strcmp(tablename, "mangle") != 0) {
 100                         printk(KERN_WARNING "CONNMARK: restore can only be "
 101                                "called from \"mangle\" table, not \"%s\"\n",
 102                                tablename);
 103                         return 0;
 104                 }
 105         }
 106         if (matchinfo->mark > 0xffffffff || matchinfo->mask > 0xffffffff) {
 107                 printk(KERN_WARNING "CONNMARK: Only supports 32bit mark\n");
 108                 return 0;
 109         }
 110         return 1;
 111 }
 112
 113 static struct xt_target xt_connmark_target[] = {
 114         {
 115                 .name           = "CONNMARK",
 116                 .family         = AF_INET,
 117                 .checkentry     = checkentry,
 118                 .target         = target,
 119                 .targetsize     = sizeof(struct xt_connmark_target_info),
 120                 .me             = THIS_MODULE
 121         },
 122         {
 123                 .name           = "CONNMARK",
 124                 .family         = AF_INET6,
 125                 .checkentry     = checkentry,
 126                 .target         = target,
 127                 .targetsize     = sizeof(struct xt_connmark_target_info),
 128                 .me             = THIS_MODULE
 129         },
 130 };
 131
 132 static int __init xt_connmark_init(void)
 133 {
 134         need_conntrack();
 135         return xt_register_targets(xt_connmark_target,
 136                                    ARRAY_SIZE(xt_connmark_target));
 137 }
 138
 139 static void __exit xt_connmark_fini(void)
 140 {
 141         xt_unregister_targets(xt_connmark_target,
 142                               ARRAY_SIZE(xt_connmark_target));
 143 }
 144
 145 module_init(xt_connmark_init);
 146 module_exit(xt_connmark_fini);