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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  19 #include <linux/module.h>
  20 #include <linux/skbuff.h>
  21 #include <linux/netfilter/x_tables.h>
  22 #include <linux/netfilter/xt_CONNSECMARK.h>
  23 #include <net/netfilter/nf_conntrack.h>
  24 #include <net/netfilter/nf_conntrack_ecache.h>
  25
  26 MODULE_LICENSE("GPL");
  27 MODULE_AUTHOR("James Morris <jmorris@redhat.com>");
  28 MODULE_DESCRIPTION("Xtables: target for copying between connection and security mark");
  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                         nf_conntrack_event_cache(IPCT_SECMARK, ct);
  46                 }
  47         }
  48 }
  49
  50 /*
  51  * If packet has no security mark, and the connection does, restore the
  52  * security mark from the connection to the packet.
  53  */
  54 static void secmark_restore(struct sk_buff *skb)
  55 {
  56         if (!skb->secmark) {
  57                 const struct nf_conn *ct;
  58                 enum ip_conntrack_info ctinfo;
  59
  60                 ct = nf_ct_get(skb, &ctinfo);
  61                 if (ct && ct->secmark)
  62                         skb->secmark = ct->secmark;
  63         }
  64 }
  65
  66 static unsigned int
  67 connsecmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
  68 {
  69         const struct xt_connsecmark_target_info *info = par->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 int connsecmark_tg_check(const struct xt_tgchk_param *par)
  88 {
  89         const struct xt_connsecmark_target_info *info = par->targinfo;
  90         int ret;
  91
  92         if (strcmp(par->table, "mangle") != 0 &&
  93             strcmp(par->table, "security") != 0) {
  94                 pr_info_ratelimited("only valid in \'mangle\' or \'security\' table, not \'%s\'\n",
  95                                     par->table);
  96                 return -EINVAL;
  97         }
  98
  99         switch (info->mode) {
 100         case CONNSECMARK_SAVE:
 101         case CONNSECMARK_RESTORE:
 102                 break;
 103
 104         default:
 105                 pr_info_ratelimited("invalid mode: %hu\n", info->mode);
 106                 return -EINVAL;
 107         }
 108
 109         ret = nf_ct_netns_get(par->net, par->family);
 110         if (ret < 0)
 111                 pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
 112                                     par->family);
 113         return ret;
 114 }
 115
 116 static void connsecmark_tg_destroy(const struct xt_tgdtor_param *par)
 117 {
 118         nf_ct_netns_put(par->net, par->family);
 119 }
 120
 121 static struct xt_target connsecmark_tg_reg __read_mostly = {
 122         .name       = "CONNSECMARK",
 123         .revision   = 0,
 124         .family     = NFPROTO_UNSPEC,
 125         .checkentry = connsecmark_tg_check,
 126         .destroy    = connsecmark_tg_destroy,
 127         .target     = connsecmark_tg,
 128         .targetsize = sizeof(struct xt_connsecmark_target_info),
 129         .me         = THIS_MODULE,
 130 };
 131
 132 static int __init connsecmark_tg_init(void)
 133 {
 134         return xt_register_target(&connsecmark_tg_reg);
 135 }
 136
 137 static void __exit connsecmark_tg_exit(void)
 138 {
 139         xt_unregister_target(&connsecmark_tg_reg);
 140 }
 141
 142 module_init(connsecmark_tg_init);
 143 module_exit(connsecmark_tg_exit);