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.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(const struct sk_buff *skb)
  37 {
  38         if (skb->secmark) {
  39                 struct nf_conn *ct;
  40                 enum ip_conntrack_info ctinfo;
  41
  42                 ct = nf_ct_get(skb, &ctinfo);
  43                 if (ct && !ct->secmark)
  44                         ct->secmark = skb->secmark;
  45         }
  46 }
  47
  48 /*
  49  * If packet has no security mark, and the connection does, restore the
  50  * security mark from the connection to the packet.
  51  */
  52 static void secmark_restore(struct sk_buff *skb)
  53 {
  54         if (!skb->secmark) {
  55                 struct nf_conn *ct;
  56                 enum ip_conntrack_info ctinfo;
  57
  58                 ct = nf_ct_get(skb, &ctinfo);
  59                 if (ct && ct->secmark)
  60                         skb->secmark = ct->secmark;
  61         }
  62 }
  63
  64 static unsigned int target(struct sk_buff *skb, const struct net_device *in,
  65                            const struct net_device *out, unsigned int hooknum,
  66                            const struct xt_target *target,
  67                            const void *targinfo)
  68 {
  69         const struct xt_connsecmark_target_info *info = targinfo;
  70
  71         switch (info->mode) {
  72         case CONNSECMARK_SAVE:
  73                 secmark_save(skb);
  74                 break;
  75
  76         case CONNSECMARK_RESTORE:
  77                 secmark_restore(skb);
  78                 break;
  79
  80         default:
  81                 BUG();
  82         }
  83
  84         return XT_CONTINUE;
  85 }
  86
  87 static bool checkentry(const char *tablename, const void *entry,
  88                        const struct xt_target *target, void *targinfo,
  89                        unsigned int hook_mask)
  90 {
  91         const struct xt_connsecmark_target_info *info = targinfo;
  92
  93         if (nf_ct_l3proto_try_module_get(target->family) < 0) {
  94                 printk(KERN_WARNING "can't load conntrack support for "
  95                                     "proto=%d\n", target->family);
  96                 return false;
  97         }
  98         switch (info->mode) {
  99         case CONNSECMARK_SAVE:
 100         case CONNSECMARK_RESTORE:
 101                 break;
 102
 103         default:
 104                 printk(KERN_INFO PFX "invalid mode: %hu\n", info->mode);
 105                 return false;
 106         }
 107
 108         return true;
 109 }
 110
 111 static void
 112 destroy(const struct xt_target *target, void *targinfo)
 113 {
 114         nf_ct_l3proto_module_put(target->family);
 115 }
 116
 117 static struct xt_target xt_connsecmark_target[] __read_mostly = {
 118         {
 119                 .name           = "CONNSECMARK",
 120                 .family         = AF_INET,
 121                 .checkentry     = checkentry,
 122                 .destroy        = destroy,
 123                 .target         = target,
 124                 .targetsize     = sizeof(struct xt_connsecmark_target_info),
 125                 .table          = "mangle",
 126                 .me             = THIS_MODULE,
 127         },
 128         {
 129                 .name           = "CONNSECMARK",
 130                 .family         = AF_INET6,
 131                 .checkentry     = checkentry,
 132                 .destroy        = destroy,
 133                 .target         = target,
 134                 .targetsize     = sizeof(struct xt_connsecmark_target_info),
 135                 .table          = "mangle",
 136                 .me             = THIS_MODULE,
 137         },
 138 };
 139
 140 static int __init xt_connsecmark_init(void)
 141 {
 142         return xt_register_targets(xt_connsecmark_target,
 143                                    ARRAY_SIZE(xt_connsecmark_target));
 144 }
 145
 146 static void __exit xt_connsecmark_fini(void)
 147 {
 148         xt_unregister_targets(xt_connsecmark_target,
 149                               ARRAY_SIZE(xt_connsecmark_target));
 150 }
 151
 152 module_init(xt_connsecmark_init);
 153 module_exit(xt_connsecmark_fini);