kernel/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         const struct net *net;
  44
  45         if (ops->hooknum == NF_INET_LOCAL_OUT &&
  46             (skb->len < sizeof(struct iphdr) ||
  47              ip_hdrlen(skb) < sizeof(struct iphdr)))
  48                 /* Somebody is playing with raw sockets. */
  49                 return NF_ACCEPT;
  50
  51         net = dev_net(state->in ? state->in : state->out);
  52         return ipt_do_table(skb, ops->hooknum, state,
  53                             net->ipv4.iptable_security);
  54 }
  55
  56 static struct nf_hook_ops *sectbl_ops __read_mostly;
  57
  58 static int __net_init iptable_security_net_init(struct net *net)
  59 {
  60         struct ipt_replace *repl;
  61
  62         repl = ipt_alloc_initial_table(&security_table);
  63         if (repl == NULL)
  64                 return -ENOMEM;
  65         net->ipv4.iptable_security =
  66                 ipt_register_table(net, &security_table, repl);
  67         kfree(repl);
  68         return PTR_ERR_OR_ZERO(net->ipv4.iptable_security);
  69 }
  70
  71 static void __net_exit iptable_security_net_exit(struct net *net)
  72 {
  73         ipt_unregister_table(net, net->ipv4.iptable_security);
  74 }
  75
  76 static struct pernet_operations iptable_security_net_ops = {
  77         .init = iptable_security_net_init,
  78         .exit = iptable_security_net_exit,
  79 };
  80
  81 static int __init iptable_security_init(void)
  82 {
  83         int ret;
  84
  85         ret = register_pernet_subsys(&iptable_security_net_ops);
  86         if (ret < 0)
  87                 return ret;
  88
  89         sectbl_ops = xt_hook_link(&security_table, iptable_security_hook);
  90         if (IS_ERR(sectbl_ops)) {
  91                 ret = PTR_ERR(sectbl_ops);
  92                 goto cleanup_table;
  93         }
  94
  95         return ret;
  96
  97 cleanup_table:
  98         unregister_pernet_subsys(&iptable_security_net_ops);
  99         return ret;
 100 }
 101
 102 static void __exit iptable_security_fini(void)
 103 {
 104         xt_hook_unlink(&security_table, sectbl_ops);
 105         unregister_pernet_subsys(&iptable_security_net_ops);
 106 }
 107
 108 module_init(iptable_security_init);
 109 module_exit(iptable_security_fini);