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(unsigned int hook, 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 (hook == 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, hook, in, out, net->ipv4.iptable_security);
  55}
  56
  57static struct nf_hook_ops *sectbl_ops __read_mostly;
  58
  59static int __net_init iptable_security_net_init(struct net *net)
  60{
  61        struct ipt_replace *repl;
  62
  63        repl = ipt_alloc_initial_table(&security_table);
  64        if (repl == NULL)
  65                return -ENOMEM;
  66        net->ipv4.iptable_security =
  67                ipt_register_table(net, &security_table, repl);
  68        kfree(repl);
  69        return PTR_RET(net->ipv4.iptable_security);
  70}
  71
  72static void __net_exit iptable_security_net_exit(struct net *net)
  73{
  74        ipt_unregister_table(net, net->ipv4.iptable_security);
  75}
  76
  77static struct pernet_operations iptable_security_net_ops = {
  78        .init = iptable_security_net_init,
  79        .exit = iptable_security_net_exit,
  80};
  81
  82static int __init iptable_security_init(void)
  83{
  84        int ret;
  85
  86        ret = register_pernet_subsys(&iptable_security_net_ops);
  87        if (ret < 0)
  88                return ret;
  89
  90        sectbl_ops = xt_hook_link(&security_table, iptable_security_hook);
  91        if (IS_ERR(sectbl_ops)) {
  92                ret = PTR_ERR(sectbl_ops);
  93                goto cleanup_table;
  94        }
  95
  96        return ret;
  97
  98cleanup_table:
  99        unregister_pernet_subsys(&iptable_security_net_ops);
 100        return ret;
 101}
 102
 103static void __exit iptable_security_fini(void)
 104{
 105        xt_hook_unlink(&security_table, sectbl_ops);
 106        unregister_pernet_subsys(&iptable_security_net_ops);
 107}
 108
 109module_init(iptable_security_init);
 110module_exit(iptable_security_fini);
 111