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 {
  43         const struct xt_connmark_target_info *markinfo = targinfo;
  44         u_int32_t diff;
  45         u_int32_t nfmark;
  46         u_int32_t newmark;
  47         u_int32_t ctinfo;
  48         u_int32_t *ctmark = nf_ct_get_mark(*pskb, &ctinfo);
  49
  50         if (ctmark) {
  51                 switch(markinfo->mode) {
  52                 case XT_CONNMARK_SET:
  53                         newmark = (*ctmark & ~markinfo->mask) | markinfo->mark;
  54                         if (newmark != *ctmark) {
  55                                 *ctmark = newmark;
  56 #ifdef CONFIG_IP_NF_CONNTRACK_EVENTS
  57                                 ip_conntrack_event_cache(IPCT_MARK, *pskb);
  58 #else
  59                                 nf_conntrack_event_cache(IPCT_MARK, *pskb);
  60 #endif
  61                 }
  62                         break;
  63                 case XT_CONNMARK_SAVE:
  64                         newmark = (*ctmark & ~markinfo->mask) |
  65                                   ((*pskb)->nfmark & markinfo->mask);
  66                         if (*ctmark != newmark) {
  67                                 *ctmark = newmark;
  68 #ifdef CONFIG_IP_NF_CONNTRACK_EVENTS
  69                                 ip_conntrack_event_cache(IPCT_MARK, *pskb);
  70 #else
  71                                 nf_conntrack_event_cache(IPCT_MARK, *pskb);
  72 #endif
  73                         }
  74                         break;
  75                 case XT_CONNMARK_RESTORE:
  76                         nfmark = (*pskb)->nfmark;
  77                         diff = (*ctmark ^ nfmark) & markinfo->mask;
  78                         if (diff != 0)
  79                                 (*pskb)->nfmark = nfmark ^ diff;
  80                         break;
  81                 }
  82         }
  83
  84         return XT_CONTINUE;
  85 }
  86
  87 static int
  88 checkentry(const char *tablename,
  89            const void *entry,
  90            const struct xt_target *target,
  91            void *targinfo,
  92            unsigned int hook_mask)
  93 {
  94         struct xt_connmark_target_info *matchinfo = targinfo;
  95
  96         if (matchinfo->mode == XT_CONNMARK_RESTORE) {
  97                 if (strcmp(tablename, "mangle") != 0) {
  98                         printk(KERN_WARNING "CONNMARK: restore can only be "
  99                                "called from \"mangle\" table, not \"%s\"\n",
 100                                tablename);
 101                         return 0;
 102                 }
 103         }
 104         if (matchinfo->mark > 0xffffffff || matchinfo->mask > 0xffffffff) {
 105                 printk(KERN_WARNING "CONNMARK: Only supports 32bit mark\n");
 106                 return 0;
 107         }
 108         return 1;
 109 }
 110
 111 static struct xt_target xt_connmark_target[] = {
 112         {
 113                 .name           = "CONNMARK",
 114                 .family         = AF_INET,
 115                 .checkentry     = checkentry,
 116                 .target         = target,
 117                 .targetsize     = sizeof(struct xt_connmark_target_info),
 118                 .me             = THIS_MODULE
 119         },
 120         {
 121                 .name           = "CONNMARK",
 122                 .family         = AF_INET6,
 123                 .checkentry     = checkentry,
 124                 .target         = target,
 125                 .targetsize     = sizeof(struct xt_connmark_target_info),
 126                 .me             = THIS_MODULE
 127         },
 128 };
 129
 130 static int __init xt_connmark_init(void)
 131 {
 132         need_conntrack();
 133         return xt_register_targets(xt_connmark_target,
 134                                    ARRAY_SIZE(xt_connmark_target));
 135 }
 136
 137 static void __exit xt_connmark_fini(void)
 138 {
 139         xt_unregister_targets(xt_connmark_target,
 140                               ARRAY_SIZE(xt_connmark_target));
 141 }
 142
 143 module_init(xt_connmark_init);
 144 module_exit(xt_connmark_fini);