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) 2006,2008 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 #include <net/netfilter/nf_conntrack_ecache.h>
  24
  25 #define PFX "CONNSECMARK: "
  26
  27 MODULE_LICENSE("GPL");
  28 MODULE_AUTHOR("James Morris <jmorris@redhat.com>");
  29 MODULE_DESCRIPTION("Xtables: target for copying between connection and security mark");
  30 MODULE_ALIAS("ipt_CONNSECMARK");
  31 MODULE_ALIAS("ip6t_CONNSECMARK");
  32
  33 /*
  34  * If the packet has a security mark and the connection does not, copy
  35  * the security mark from the packet to the connection.
  36  */
  37 static void secmark_save(const struct sk_buff *skb)
  38 {
  39         if (skb->secmark) {
  40                 struct nf_conn *ct;
  41                 enum ip_conntrack_info ctinfo;
  42
  43                 ct = nf_ct_get(skb, &ctinfo);
  44                 if (ct && !ct->secmark) {
  45                         ct->secmark = skb->secmark;
  46                         nf_conntrack_event_cache(IPCT_SECMARK, skb);
  47                 }
  48         }
  49 }
  50
  51 /*
  52  * If packet has no security mark, and the connection does, restore the
  53  * security mark from the connection to the packet.
  54  */
  55 static void secmark_restore(struct sk_buff *skb)
  56 {
  57         if (!skb->secmark) {
  58                 const struct nf_conn *ct;
  59                 enum ip_conntrack_info ctinfo;
  60
  61                 ct = nf_ct_get(skb, &ctinfo);
  62                 if (ct && ct->secmark)
  63                         skb->secmark = ct->secmark;
  64         }
  65 }
  66
  67 static unsigned int
  68 connsecmark_tg(struct sk_buff *skb, const struct net_device *in,
  69                const struct net_device *out, unsigned int hooknum,
  70                const struct xt_target *target, const void *targinfo)
  71 {
  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 bool
  91 connsecmark_tg_check(const char *tablename, const void *entry,
  92                      const struct xt_target *target, void *targinfo,
  93                      unsigned int hook_mask)
  94 {
  95         const struct xt_connsecmark_target_info *info = targinfo;
  96
  97         if (strcmp(tablename, "mangle") && strcmp(tablename, "security")) {
  98                 printk(KERN_INFO PFX "target only valid in the \'mangle\' "
  99                        "or \'security\' tables, not \'%s\'.\n", tablename);
 100                 return false;
 101         }
 102
 103         switch (info->mode) {
 104         case CONNSECMARK_SAVE:
 105         case CONNSECMARK_RESTORE:
 106                 break;
 107
 108         default:
 109                 printk(KERN_INFO PFX "invalid mode: %hu\n", info->mode);
 110                 return false;
 111         }
 112
 113         if (nf_ct_l3proto_try_module_get(target->family) < 0) {
 114                 printk(KERN_WARNING "can't load conntrack support for "
 115                                     "proto=%u\n", target->family);
 116                 return false;
 117         }
 118         return true;
 119 }
 120
 121 static void
 122 connsecmark_tg_destroy(const struct xt_target *target, void *targinfo)
 123 {
 124         nf_ct_l3proto_module_put(target->family);
 125 }
 126
 127 static struct xt_target connsecmark_tg_reg[] __read_mostly = {
 128         {
 129                 .name           = "CONNSECMARK",
 130                 .family         = AF_INET,
 131                 .checkentry     = connsecmark_tg_check,
 132                 .destroy        = connsecmark_tg_destroy,
 133                 .target         = connsecmark_tg,
 134                 .targetsize     = sizeof(struct xt_connsecmark_target_info),
 135                 .me             = THIS_MODULE,
 136         },
 137         {
 138                 .name           = "CONNSECMARK",
 139                 .family         = AF_INET6,
 140                 .checkentry     = connsecmark_tg_check,
 141                 .destroy        = connsecmark_tg_destroy,
 142                 .target         = connsecmark_tg,
 143                 .targetsize     = sizeof(struct xt_connsecmark_target_info),
 144                 .me             = THIS_MODULE,
 145         },
 146 };
 147
 148 static int __init connsecmark_tg_init(void)
 149 {
 150         return xt_register_targets(connsecmark_tg_reg,
 151                ARRAY_SIZE(connsecmark_tg_reg));
 152 }
 153
 154 static void __exit connsecmark_tg_exit(void)
 155 {
 156         xt_unregister_targets(connsecmark_tg_reg,
 157                               ARRAY_SIZE(connsecmark_tg_reg));
 158 }
 159
 160 module_init(connsecmark_tg_init);
 161 module_exit(connsecmark_tg_exit);