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, ct);
  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 xt_target_param *par)
  69 {
  70         const struct xt_connsecmark_target_info *info = par->targinfo;
  71
  72         switch (info->mode) {
  73         case CONNSECMARK_SAVE:
  74                 secmark_save(skb);
  75                 break;
  76
  77         case CONNSECMARK_RESTORE:
  78                 secmark_restore(skb);
  79                 break;
  80
  81         default:
  82                 BUG();
  83         }
  84
  85         return XT_CONTINUE;
  86 }
  87
  88 static bool connsecmark_tg_check(const struct xt_tgchk_param *par)
  89 {
  90         const struct xt_connsecmark_target_info *info = par->targinfo;
  91
  92         if (strcmp(par->table, "mangle") != 0 &&
  93             strcmp(par->table, "security") != 0) {
  94                 printk(KERN_INFO PFX "target only valid in the \'mangle\' "
  95                        "or \'security\' tables, not \'%s\'.\n", par->table);
  96                 return false;
  97         }
  98
  99         switch (info->mode) {
 100         case CONNSECMARK_SAVE:
 101         case CONNSECMARK_RESTORE:
 102                 break;
 103
 104         default:
 105                 printk(KERN_INFO PFX "invalid mode: %hu\n", info->mode);
 106                 return false;
 107         }
 108
 109         if (nf_ct_l3proto_try_module_get(par->family) < 0) {
 110                 printk(KERN_WARNING "can't load conntrack support for "
 111                                     "proto=%u\n", par->family);
 112                 return false;
 113         }
 114         return true;
 115 }
 116
 117 static void connsecmark_tg_destroy(const struct xt_tgdtor_param *par)
 118 {
 119         nf_ct_l3proto_module_put(par->family);
 120 }
 121
 122 static struct xt_target connsecmark_tg_reg __read_mostly = {
 123         .name       = "CONNSECMARK",
 124         .revision   = 0,
 125         .family     = NFPROTO_UNSPEC,
 126         .checkentry = connsecmark_tg_check,
 127         .destroy    = connsecmark_tg_destroy,
 128         .target     = connsecmark_tg,
 129         .targetsize = sizeof(struct xt_connsecmark_target_info),
 130         .me         = THIS_MODULE,
 131 };
 132
 133 static int __init connsecmark_tg_init(void)
 134 {
 135         return xt_register_target(&connsecmark_tg_reg);
 136 }
 137
 138 static void __exit connsecmark_tg_exit(void)
 139 {
 140         xt_unregister_target(&connsecmark_tg_reg);
 141 }
 142
 143 module_init(connsecmark_tg_init);
 144 module_exit(connsecmark_tg_exit);