LXR linux/net/ipv4/netfilter/iptable

   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
  23MODULE_LICENSE("GPL");
  24MODULE_AUTHOR("James Morris <jmorris <at> redhat.com>");
  25MODULE_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
  31static int __net_init iptable_security_table_init(struct net *net);
  32
  33static 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
  42static unsigned int
  43iptable_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
  55static struct nf_hook_ops *sectbl_ops __read_mostly;
  56
  57static 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
  74static 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
  83static struct pernet_operations iptable_security_net_ops = {
  84        .exit = iptable_security_net_exit,
  85};
  86
  87static 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
 110static void __exit iptable_security_fini(void)
 111{
 112        unregister_pernet_subsys(&iptable_security_net_ops);
 113        kfree(sectbl_ops);
 114}
 115
 116module_init(iptable_security_init);
 117module_exit(iptable_security_fini);
 118