root/net/ipv4/netfilter/iptable_security.c

DEFINITIONS

1. ipt_local_in_hook
2. ipt_forward_hook
3. ipt_local_out_hook
4. iptable_security_net_init
5. iptable_security_net_exit
6. iptable_security_init
7. iptable_security_fini

/*
 * "security" table
 *
 * This is for use by Mandatory Access Control (MAC) security models,
 * which need to be able to manage security policy in separate context
 * to DAC.
 *
 * Based on iptable_mangle.c
 *
 * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
 * Copyright (C) 2000-2004 Netfilter Core Team <coreteam <at> netfilter.org>
 * Copyright (C) 2008 Red Hat, Inc., James Morris <jmorris <at> redhat.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/module.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <net/ip.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("James Morris <jmorris <at> redhat.com>");
MODULE_DESCRIPTION("iptables security table, for MAC rules");

#define SECURITY_VALID_HOOKS    (1 << NF_INET_LOCAL_IN) | \
                                (1 << NF_INET_FORWARD) | \
                                (1 << NF_INET_LOCAL_OUT)

static struct
{
        struct ipt_replace repl;
        struct ipt_standard entries[3];
        struct ipt_error term;
} initial_table __net_initdata = {
        .repl = {
                .name = "security",
                .valid_hooks = SECURITY_VALID_HOOKS,
                .num_entries = 4,
                .size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
                .hook_entry = {
                        [NF_INET_LOCAL_IN]      = 0,
                        [NF_INET_FORWARD]       = sizeof(struct ipt_standard),
                        [NF_INET_LOCAL_OUT]     = sizeof(struct ipt_standard) * 2,
                },
                .underflow = {
                        [NF_INET_LOCAL_IN]      = 0,
                        [NF_INET_FORWARD]       = sizeof(struct ipt_standard),
                        [NF_INET_LOCAL_OUT]     = sizeof(struct ipt_standard) * 2,
                },
        },
        .entries = {
                IPT_STANDARD_INIT(NF_ACCEPT),   /* LOCAL_IN */
                IPT_STANDARD_INIT(NF_ACCEPT),   /* FORWARD */
                IPT_STANDARD_INIT(NF_ACCEPT),   /* LOCAL_OUT */
        },
        .term = IPT_ERROR_INIT,                 /* ERROR */
};

static struct xt_table security_table = {
        .name           = "security",
        .valid_hooks    = SECURITY_VALID_HOOKS,
        .lock           = __RW_LOCK_UNLOCKED(security_table.lock),
        .me             = THIS_MODULE,
        .af             = AF_INET,
};

static unsigned int
ipt_local_in_hook(unsigned int hook,
                  struct sk_buff *skb,
                  const struct net_device *in,
                  const struct net_device *out,
                  int (*okfn)(struct sk_buff *))
{
        return ipt_do_table(skb, hook, in, out,
                            dev_net(in)->ipv4.iptable_security);
}

static unsigned int
ipt_forward_hook(unsigned int hook,
                 struct sk_buff *skb,
                 const struct net_device *in,
                 const struct net_device *out,
                 int (*okfn)(struct sk_buff *))
{
        return ipt_do_table(skb, hook, in, out,
                            dev_net(in)->ipv4.iptable_security);
}

static unsigned int
ipt_local_out_hook(unsigned int hook,
                   struct sk_buff *skb,
                   const struct net_device *in,
                   const struct net_device *out,
                   int (*okfn)(struct sk_buff *))
{
        /* Somebody is playing with raw sockets. */
        if (skb->len < sizeof(struct iphdr)
            || ip_hdrlen(skb) < sizeof(struct iphdr)) {
                if (net_ratelimit())
                        printk(KERN_INFO "iptable_security: ignoring short "
                               "SOCK_RAW packet.\n");
                return NF_ACCEPT;
        }
        return ipt_do_table(skb, hook, in, out,
                            dev_net(out)->ipv4.iptable_security);
}

static struct nf_hook_ops ipt_ops[] __read_mostly = {
        {
                .hook           = ipt_local_in_hook,
                .owner          = THIS_MODULE,
                .pf             = PF_INET,
                .hooknum        = NF_INET_LOCAL_IN,
                .priority       = NF_IP_PRI_SECURITY,
        },
        {
                .hook           = ipt_forward_hook,
                .owner          = THIS_MODULE,
                .pf             = PF_INET,
                .hooknum        = NF_INET_FORWARD,
                .priority       = NF_IP_PRI_SECURITY,
        },
        {
                .hook           = ipt_local_out_hook,
                .owner          = THIS_MODULE,
                .pf             = PF_INET,
                .hooknum        = NF_INET_LOCAL_OUT,
                .priority       = NF_IP_PRI_SECURITY,
        },
};

static int __net_init iptable_security_net_init(struct net *net)
{
        net->ipv4.iptable_security =
                ipt_register_table(net, &security_table, &initial_table.repl);

        if (IS_ERR(net->ipv4.iptable_security))
                return PTR_ERR(net->ipv4.iptable_security);

        return 0;
}

static void __net_exit iptable_security_net_exit(struct net *net)
{
        ipt_unregister_table(net->ipv4.iptable_security);
}

static struct pernet_operations iptable_security_net_ops = {
        .init = iptable_security_net_init,
        .exit = iptable_security_net_exit,
};

static int __init iptable_security_init(void)
{
        int ret;

        ret = register_pernet_subsys(&iptable_security_net_ops);
        if (ret < 0)
                return ret;

        ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
        if (ret < 0)
                goto cleanup_table;

        return ret;

cleanup_table:
        unregister_pernet_subsys(&iptable_security_net_ops);
        return ret;
}

static void __exit iptable_security_fini(void)
{
        nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
        unregister_pernet_subsys(&iptable_security_net_ops);
}

module_init(iptable_security_init);
module_exit(iptable_security_fini);