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 const struct xt_table security_table = {
  32         .name           = "security",
  33         .valid_hooks    = SECURITY_VALID_HOOKS,
  34         .me             = THIS_MODULE,
  35         .af             = NFPROTO_IPV4,
  36         .priority       = NF_IP_PRI_SECURITY,
  37 };
  38
  39 static unsigned int
  40 iptable_security_hook(const struct nf_hook_ops *ops, struct sk_buff *skb,
  41                       const struct nf_hook_state *state)
  42 {
  43         if (ops->hooknum == NF_INET_LOCAL_OUT &&
  44             (skb->len < sizeof(struct iphdr) ||
  45              ip_hdrlen(skb) < sizeof(struct iphdr)))
  46                 /* Somebody is playing with raw sockets. */
  47                 return NF_ACCEPT;
  48
  49         return ipt_do_table(skb, ops->hooknum, state,
  50                             state->net->ipv4.iptable_security);
  51 }
  52
  53 static struct nf_hook_ops *sectbl_ops __read_mostly;
  54
  55 static int __net_init iptable_security_net_init(struct net *net)
  56 {
  57         struct ipt_replace *repl;
  58
  59         repl = ipt_alloc_initial_table(&security_table);
  60         if (repl == NULL)
  61                 return -ENOMEM;
  62         net->ipv4.iptable_security =
  63                 ipt_register_table(net, &security_table, repl);
  64         kfree(repl);
  65         return PTR_ERR_OR_ZERO(net->ipv4.iptable_security);
  66 }
  67
  68 static void __net_exit iptable_security_net_exit(struct net *net)
  69 {
  70         ipt_unregister_table(net, net->ipv4.iptable_security);
  71 }
  72
  73 static struct pernet_operations iptable_security_net_ops = {
  74         .init = iptable_security_net_init,
  75         .exit = iptable_security_net_exit,
  76 };
  77
  78 static int __init iptable_security_init(void)
  79 {
  80         int ret;
  81
  82         ret = register_pernet_subsys(&iptable_security_net_ops);
  83         if (ret < 0)
  84                 return ret;
  85
  86         sectbl_ops = xt_hook_link(&security_table, iptable_security_hook);
  87         if (IS_ERR(sectbl_ops)) {
  88                 ret = PTR_ERR(sectbl_ops);
  89                 goto cleanup_table;
  90         }
  91
  92         return ret;
  93
  94 cleanup_table:
  95         unregister_pernet_subsys(&iptable_security_net_ops);
  96         return ret;
  97 }
  98
  99 static void __exit iptable_security_fini(void)
 100 {
 101         xt_hook_unlink(&security_table, sectbl_ops);
 102         unregister_pernet_subsys(&iptable_security_net_ops);
 103 }
 104
 105 module_init(iptable_security_init);
 106 module_exit(iptable_security_fini);