net/ipv4/netfilter/iptable_security.c

   1 /*
   2  * "security" table
   3  *
   4  * This is for use by Mandatory Access Control (MAC) security models,
   5  * which need to be able to manage security policy in separate context
   6  * to DAC.
   7  *
   8  * Based on iptable_mangle.c
   9  *
  10  * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
  11  * Copyright (C) 2000-2004 Netfilter Core Team <coreteam <at> netfilter.org>
  12  * Copyright (C) 2008 Red Hat, Inc., James Morris <jmorris <at> redhat.com>
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License version 2 as
  16  * published by the Free Software Foundation.
  17  */
  18 #include <linux/module.h>
  19 #include <linux/netfilter_ipv4/ip_tables.h>
  20 #include <linux/slab.h>
  21 #include <net/ip.h>
  22
  23 MODULE_LICENSE("GPL");
  24 MODULE_AUTHOR("James Morris <jmorris <at> redhat.com>");
  25 MODULE_DESCRIPTION("iptables security table, for MAC rules");
  26
  27 #define SECURITY_VALID_HOOKS    (1 << NF_INET_LOCAL_IN) | \
  28                                 (1 << NF_INET_FORWARD) | \
  29                                 (1 << NF_INET_LOCAL_OUT)
  30
  31 static int __net_init iptable_security_table_init(struct net *net);
  32
  33 static const struct xt_table security_table = {
  34         .name           = "security",
  35         .valid_hooks    = SECURITY_VALID_HOOKS,
  36         .me             = THIS_MODULE,
  37         .af             = NFPROTO_IPV4,
  38         .priority       = NF_IP_PRI_SECURITY,
  39         .table_init     = iptable_security_table_init,
  40 };
  41
  42 static unsigned int
  43 iptable_security_hook(void *priv, struct sk_buff *skb,
  44                       const struct nf_hook_state *state)
  45 {
  46         if (state->hook == NF_INET_LOCAL_OUT &&
  47             (skb->len < sizeof(struct iphdr) ||
  48              ip_hdrlen(skb) < sizeof(struct iphdr)))
  49                 /* Somebody is playing with raw sockets. */
  50                 return NF_ACCEPT;
  51
  52         return ipt_do_table(skb, state, state->net->ipv4.iptable_security);
  53 }
  54
  55 static struct nf_hook_ops *sectbl_ops __read_mostly;
  56
  57 static int __net_init iptable_security_table_init(struct net *net)
  58 {
  59         struct ipt_replace *repl;
  60         int ret;
  61
  62         if (net->ipv4.iptable_security)
  63                 return 0;
  64
  65         repl = ipt_alloc_initial_table(&security_table);
  66         if (repl == NULL)
  67                 return -ENOMEM;
  68         ret = ipt_register_table(net, &security_table, repl, sectbl_ops,
  69                                  &net->ipv4.iptable_security);
  70         kfree(repl);
  71         return ret;
  72 }
  73
  74 static void __net_exit iptable_security_net_exit(struct net *net)
  75 {
  76         if (!net->ipv4.iptable_security)
  77                 return;
  78
  79         ipt_unregister_table(net, net->ipv4.iptable_security, sectbl_ops);
  80         net->ipv4.iptable_security = NULL;
  81 }
  82
  83 static struct pernet_operations iptable_security_net_ops = {
  84         .exit = iptable_security_net_exit,
  85 };
  86
  87 static int __init iptable_security_init(void)
  88 {
  89         int ret;
  90
  91         sectbl_ops = xt_hook_ops_alloc(&security_table, iptable_security_hook);
  92         if (IS_ERR(sectbl_ops))
  93                 return PTR_ERR(sectbl_ops);
  94
  95         ret = register_pernet_subsys(&iptable_security_net_ops);
  96         if (ret < 0) {
  97                 kfree(sectbl_ops);
  98                 return ret;
  99         }
 100
 101         ret = iptable_security_table_init(&init_net);
 102         if (ret) {
 103                 unregister_pernet_subsys(&iptable_security_net_ops);
 104                 kfree(sectbl_ops);
 105         }
 106
 107         return ret;
 108 }
 109
 110 static void __exit iptable_security_fini(void)
 111 {
 112         unregister_pernet_subsys(&iptable_security_net_ops);
 113         kfree(sectbl_ops);
 114 }
 115
 116 module_init(iptable_security_init);
 117 module_exit(iptable_security_fini);