net/netfilter/xt_CONNSECMARK.c

   1 /*
   2  * This module is used to copy security markings from packets
   3  * to connections, and restore security markings from connections
   4  * back to packets.  This would normally be performed in conjunction
   5  * with the SECMARK target and state match.
   6  *
   7  * Based somewhat on CONNMARK:
   8  *   Copyright (C) 2002,2004 MARA Systems AB <http://www.marasystems.com>
   9  *    by Henrik Nordstrom <hno@marasystems.com>
  10  *
  11  * (C) 2006 Red Hat, Inc., James Morris <jmorris@redhat.com>
  12  *
  13  * This program is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License version 2 as
  15  * published by the Free Software Foundation.
  16  *
  17  */
  18 #include <linux/module.h>
  19 #include <linux/skbuff.h>
  20 #include <linux/netfilter/x_tables.h>
  21 #include <linux/netfilter/xt_CONNSECMARK.h>
  22 #include <net/netfilter/nf_conntrack_compat.h>
  23
  24 #define PFX "CONNSECMARK: "
  25
  26 MODULE_LICENSE("GPL");
  27 MODULE_AUTHOR("James Morris <jmorris@redhat.com>");
  28 MODULE_DESCRIPTION("ip[6]tables CONNSECMARK module");
  29 MODULE_ALIAS("ipt_CONNSECMARK");
  30 MODULE_ALIAS("ip6t_CONNSECMARK");
  31
  32 /*
  33  * If the packet has a security mark and the connection does not, copy
  34  * the security mark from the packet to the connection.
  35  */
  36 static void secmark_save(struct sk_buff *skb)
  37 {
  38         if (skb->secmark) {
  39                 u32 *connsecmark;
  40                 enum ip_conntrack_info ctinfo;
  41
  42                 connsecmark = nf_ct_get_secmark(skb, &ctinfo);
  43                 if (connsecmark && !*connsecmark)
  44                         if (*connsecmark != skb->secmark)
  45                                 *connsecmark = skb->secmark;
  46         }
  47 }
  48
  49 /*
  50  * If packet has no security mark, and the connection does, restore the
  51  * security mark from the connection to the packet.
  52  */
  53 static void secmark_restore(struct sk_buff *skb)
  54 {
  55         if (!skb->secmark) {
  56                 u32 *connsecmark;
  57                 enum ip_conntrack_info ctinfo;
  58
  59                 connsecmark = nf_ct_get_secmark(skb, &ctinfo);
  60                 if (connsecmark && *connsecmark)
  61                         if (skb->secmark != *connsecmark)
  62                                 skb->secmark = *connsecmark;
  63         }
  64 }
  65
  66 static unsigned int target(struct sk_buff **pskb, const struct net_device *in,
  67                            const struct net_device *out, unsigned int hooknum,
  68                            const struct xt_target *target,
  69                            const void *targinfo)
  70 {
  71         struct sk_buff *skb = *pskb;
  72         const struct xt_connsecmark_target_info *info = targinfo;
  73
  74         switch (info->mode) {
  75         case CONNSECMARK_SAVE:
  76                 secmark_save(skb);
  77                 break;
  78
  79         case CONNSECMARK_RESTORE:
  80                 secmark_restore(skb);
  81                 break;
  82
  83         default:
  84                 BUG();
  85         }
  86
  87         return XT_CONTINUE;
  88 }
  89
  90 static int checkentry(const char *tablename, const void *entry,
  91                       const struct xt_target *target, void *targinfo,
  92                       unsigned int hook_mask)
  93 {
  94         struct xt_connsecmark_target_info *info = targinfo;
  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 0;
 100         }
 101         switch (info->mode) {
 102         case CONNSECMARK_SAVE:
 103         case CONNSECMARK_RESTORE:
 104                 break;
 105
 106         default:
 107                 printk(KERN_INFO PFX "invalid mode: %hu\n", info->mode);
 108                 return 0;
 109         }
 110
 111         return 1;
 112 }
 113
 114 static void
 115 destroy(const struct xt_target *target, void *targinfo)
 116 {
 117         nf_ct_l3proto_module_put(target->family);
 118 }
 119
 120 static struct xt_target xt_connsecmark_target[] = {
 121         {
 122                 .name           = "CONNSECMARK",
 123                 .family         = AF_INET,
 124                 .checkentry     = checkentry,
 125                 .destroy        = destroy,
 126                 .target         = target,
 127                 .targetsize     = sizeof(struct xt_connsecmark_target_info),
 128                 .table          = "mangle",
 129                 .me             = THIS_MODULE,
 130         },
 131         {
 132                 .name           = "CONNSECMARK",
 133                 .family         = AF_INET6,
 134                 .checkentry     = checkentry,
 135                 .destroy        = destroy,
 136                 .target         = target,
 137                 .targetsize     = sizeof(struct xt_connsecmark_target_info),
 138                 .table          = "mangle",
 139                 .me             = THIS_MODULE,
 140         },
 141 };
 142
 143 static int __init xt_connsecmark_init(void)
 144 {
 145         return xt_register_targets(xt_connsecmark_target,
 146                                    ARRAY_SIZE(xt_connsecmark_target));
 147 }
 148
 149 static void __exit xt_connsecmark_fini(void)
 150 {
 151         xt_unregister_targets(xt_connsecmark_target,
 152                               ARRAY_SIZE(xt_connsecmark_target));
 153 }
 154
 155 module_init(xt_connsecmark_init);
 156 module_exit(xt_connsecmark_fini);