[deliverable/linux.git] / net / ipv4 / netfilter / iptable_filter.c

/*
 * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
 *
 * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
 * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
 *
 * 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/moduleparam.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/slab.h>
#include <net/ip.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
MODULE_DESCRIPTION("iptables filter table");

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

static const struct xt_table packet_filter = {
	.name		= "filter",
	.valid_hooks	= FILTER_VALID_HOOKS,
	.me		= THIS_MODULE,
	.af		= NFPROTO_IPV4,
	.priority	= NF_IP_PRI_FILTER,
};

static unsigned int
iptable_filter_hook(const struct nf_hook_ops *ops, struct sk_buff *skb,
		    const struct nf_hook_state *state)
{
	if (state->hook == NF_INET_LOCAL_OUT &&
	    (skb->len < sizeof(struct iphdr) ||
	     ip_hdrlen(skb) < sizeof(struct iphdr)))
		/* root is playing with raw sockets. */
		return NF_ACCEPT;

	return ipt_do_table(skb, state, state->net->ipv4.iptable_filter);
}

static struct nf_hook_ops *filter_ops __read_mostly;

/* Default to forward because I got too much mail already. */
static bool forward = true;
module_param(forward, bool, 0000);

static int __net_init iptable_filter_net_init(struct net *net)
{
	struct ipt_replace *repl;

	repl = ipt_alloc_initial_table(&packet_filter);
	if (repl == NULL)
		return -ENOMEM;
	/* Entry 1 is the FORWARD hook */
	((struct ipt_standard *)repl->entries)[1].target.verdict =
		forward ? -NF_ACCEPT - 1 : -NF_DROP - 1;

	net->ipv4.iptable_filter =
		ipt_register_table(net, &packet_filter, repl);
	kfree(repl);
	return PTR_ERR_OR_ZERO(net->ipv4.iptable_filter);
}

static void __net_exit iptable_filter_net_exit(struct net *net)
{
	ipt_unregister_table(net, net->ipv4.iptable_filter);
}

static struct pernet_operations iptable_filter_net_ops = {
	.init = iptable_filter_net_init,
	.exit = iptable_filter_net_exit,
};

static int __init iptable_filter_init(void)
{
	int ret;

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

	/* Register hooks */
	filter_ops = xt_hook_link(&packet_filter, iptable_filter_hook);
	if (IS_ERR(filter_ops)) {
		ret = PTR_ERR(filter_ops);
		unregister_pernet_subsys(&iptable_filter_net_ops);
	}

	return ret;
}

static void __exit iptable_filter_fini(void)
{
	xt_hook_unlink(&packet_filter, filter_ops);
	unregister_pernet_subsys(&iptable_filter_net_ops);
}

module_init(iptable_filter_init);
module_exit(iptable_filter_fini);
Commit	Line	Data
	1	/*
	2	* This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
	3	*
	4	* Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
	5	* Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 as
	9	* published by the Free Software Foundation.
	10	*
	11	*/
	12
	13	#include <linux/module.h>
	14	#include <linux/moduleparam.h>
	15	#include <linux/netfilter_ipv4/ip_tables.h>
	16	#include <linux/slab.h>
	17	#include <net/ip.h>
	18
	19	MODULE_LICENSE("GPL");
	20	MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
	21	MODULE_DESCRIPTION("iptables filter table");
	22
	23	#define FILTER_VALID_HOOKS ((1 << NF_INET_LOCAL_IN) \| \
	24	(1 << NF_INET_FORWARD) \| \
	25	(1 << NF_INET_LOCAL_OUT))
	26
	27	static const struct xt_table packet_filter = {
	28	.name = "filter",
	29	.valid_hooks = FILTER_VALID_HOOKS,
	30	.me = THIS_MODULE,
	31	.af = NFPROTO_IPV4,
	32	.priority = NF_IP_PRI_FILTER,
	33	};
	34
	35	static unsigned int
	36	iptable_filter_hook(const struct nf_hook_ops ops, struct sk_buff skb,
	37	const struct nf_hook_state *state)
	38	{
	39	if (state->hook == NF_INET_LOCAL_OUT &&
	40	(skb->len < sizeof(struct iphdr) \|\|
	41	ip_hdrlen(skb) < sizeof(struct iphdr)))
	42	/* root is playing with raw sockets. */
	43	return NF_ACCEPT;
	44
	45	return ipt_do_table(skb, state, state->net->ipv4.iptable_filter);
	46	}
	47
	48	static struct nf_hook_ops *filter_ops __read_mostly;
	49
	50	/* Default to forward because I got too much mail already. */
	51	static bool forward = true;
	52	module_param(forward, bool, 0000);
	53
	54	static int __net_init iptable_filter_net_init(struct net *net)
	55	{
	56	struct ipt_replace *repl;
	57
	58	repl = ipt_alloc_initial_table(&packet_filter);
	59	if (repl == NULL)
	60	return -ENOMEM;
	61	/* Entry 1 is the FORWARD hook */
	62	((struct ipt_standard *)repl->entries)[1].target.verdict =
	63	forward ? -NF_ACCEPT - 1 : -NF_DROP - 1;
	64
	65	net->ipv4.iptable_filter =
	66	ipt_register_table(net, &packet_filter, repl);
	67	kfree(repl);
	68	return PTR_ERR_OR_ZERO(net->ipv4.iptable_filter);
	69	}
	70
	71	static void __net_exit iptable_filter_net_exit(struct net *net)
	72	{
	73	ipt_unregister_table(net, net->ipv4.iptable_filter);
	74	}
	75
	76	static struct pernet_operations iptable_filter_net_ops = {
	77	.init = iptable_filter_net_init,
	78	.exit = iptable_filter_net_exit,
	79	};
	80
	81	static int __init iptable_filter_init(void)
	82	{
	83	int ret;
	84
	85	ret = register_pernet_subsys(&iptable_filter_net_ops);
	86	if (ret < 0)
	87	return ret;
	88
	89	/* Register hooks */
	90	filter_ops = xt_hook_link(&packet_filter, iptable_filter_hook);
	91	if (IS_ERR(filter_ops)) {
	92	ret = PTR_ERR(filter_ops);
	93	unregister_pernet_subsys(&iptable_filter_net_ops);
	94	}
	95
	96	return ret;
	97	}
	98
	99	static void __exit iptable_filter_fini(void)
	100	{
	101	xt_hook_unlink(&packet_filter, filter_ops);
	102	unregister_pernet_subsys(&iptable_filter_net_ops);
	103	}
	104
	105	module_init(iptable_filter_init);
	106	module_exit(iptable_filter_fini);