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 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
  39static unsigned int
  40iptable_security_hook(const struct nf_hook_ops *ops, struct sk_buff *skb,
  41                      const struct net_device *in,
  42                      const struct net_device *out,
  43                      int (*okfn)(struct sk_buff *))
  44{
  45        const struct net *net;
  46
  47        if (ops->hooknum == NF_INET_LOCAL_OUT &&
  48            (skb->len < sizeof(struct iphdr) ||
  49             ip_hdrlen(skb) < sizeof(struct iphdr)))
  50                /* Somebody is playing with raw sockets. */
  51                return NF_ACCEPT;
  52
  53        net = dev_net((in != NULL) ? in : out);
  54        return ipt_do_table(skb, ops->hooknum, in, out,
  55                            net->ipv4.iptable_security);
  56}
  57
  58static struct nf_hook_ops *sectbl_ops __read_mostly;
  59
  60static int __net_init iptable_security_net_init(struct net *net)
  61{
  62        struct ipt_replace *repl;
  63
  64        repl = ipt_alloc_initial_table(&security_table);
  65        if (repl == NULL)
  66                return -ENOMEM;
  67        net->ipv4.iptable_security =
  68                ipt_register_table(net, &security_table, repl);
  69        kfree(repl);
  70        return PTR_ERR_OR_ZERO(net->ipv4.iptable_security);
  71}
  72
  73static void __net_exit iptable_security_net_exit(struct net *net)
  74{
  75        ipt_unregister_table(net, net->ipv4.iptable_security);
  76}
  77
  78static struct pernet_operations iptable_security_net_ops = {
  79        .init = iptable_security_net_init,
  80        .exit = iptable_security_net_exit,
  81};
  82
  83static int __init iptable_security_init(void)
  84{
  85        int ret;
  86
  87        ret = register_pernet_subsys(&iptable_security_net_ops);
  88        if (ret < 0)
  89                return ret;
  90
  91        sectbl_ops = xt_hook_link(&security_table, iptable_security_hook);
  92        if (IS_ERR(sectbl_ops)) {
  93                ret = PTR_ERR(sectbl_ops);
  94                goto cleanup_table;
  95        }
  96
  97        return ret;
  98
  99cleanup_table:
 100        unregister_pernet_subsys(&iptable_security_net_ops);
 101        return ret;
 102}
 103
 104static void __exit iptable_security_fini(void)
 105{
 106        xt_hook_unlink(&security_table, sectbl_ops);
 107        unregister_pernet_subsys(&iptable_security_net_ops);
 108}
 109
 110module_init(iptable_security_init);
 111module_exit(iptable_security_fini);
 112