/* * 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/netfilter_ipv4/ip_tables.h>MODULE_LICENSE("GPL");MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");MODULE_DESCRIPTION("iptables filter table");#define FILTER_VALID_HOOKS ((1 << NF_IP_LOCAL_IN) | (1 << NF_IP_FORWARD) | (1 << NF_IP_LOCAL_OUT))/* Standard entry. */struct ipt_standard{	struct ipt_entry entry;	struct ipt_standard_target target;};struct ipt_error_target{	struct ipt_entry_target target;	char errorname[IPT_FUNCTION_MAXNAMELEN];};struct ipt_error{	struct ipt_entry entry;	struct ipt_error_target target;};static struct{	struct ipt_replace repl;	struct ipt_standard entries[3];	struct ipt_error term;} initial_table __initdata= { { "filter", FILTER_VALID_HOOKS, 4,      sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),      { [NF_IP_LOCAL_IN] = 0,	[NF_IP_FORWARD] = sizeof(struct ipt_standard),	[NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 },      { [NF_IP_LOCAL_IN] = 0,	[NF_IP_FORWARD] = sizeof(struct ipt_standard),	[NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 },      0, NULL, { } },    {	    /* LOCAL_IN */	    { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },		0,		sizeof(struct ipt_entry),		sizeof(struct ipt_standard),		0, { 0, 0 }, { } },	      { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },		-NF_ACCEPT - 1 } },	    /* FORWARD */	    { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },		0,		sizeof(struct ipt_entry),		sizeof(struct ipt_standard),		0, { 0, 0 }, { } },	      { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },		-NF_ACCEPT - 1 } },	    /* LOCAL_OUT */	    { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },		0,		sizeof(struct ipt_entry),		sizeof(struct ipt_standard),		0, { 0, 0 }, { } },	      { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },		-NF_ACCEPT - 1 } }    },    /* ERROR */    { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },	0,	sizeof(struct ipt_entry),	sizeof(struct ipt_error),	0, { 0, 0 }, { } },      { { { { IPT_ALIGN(sizeof(struct ipt_error_target)), IPT_ERROR_TARGET } },	  { } },	"ERROR"      }    }};static struct ipt_table packet_filter = {	.name		= "filter",	.table		= &initial_table.repl,	.valid_hooks	= FILTER_VALID_HOOKS,	.lock		= RW_LOCK_UNLOCKED,	.me		= THIS_MODULE};/* The work comes in here from netfilter.c. */static unsigned intipt_hook(unsigned int hook,	 struct sk_buff **pskb,	 const struct net_device *in,	 const struct net_device *out,	 int (*okfn)(struct sk_buff *)){	return ipt_do_table(pskb, hook, in, out, &packet_filter, NULL);}static unsigned intipt_local_out_hook(unsigned int hook,		   struct sk_buff **pskb,		   const struct net_device *in,		   const struct net_device *out,		   int (*okfn)(struct sk_buff *)){	/* root is playing with raw sockets. */	if ((*pskb)->len < sizeof(struct iphdr)	    || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr)) {		if (net_ratelimit())			printk("ipt_hook: happy cracking.\n");		return NF_ACCEPT;	}	return ipt_do_table(pskb, hook, in, out, &packet_filter, NULL);}static struct nf_hook_ops ipt_ops[] = {	{		.hook		= ipt_hook,		.owner		= THIS_MODULE,		.pf		= PF_INET,		.hooknum	= NF_IP_LOCAL_IN,		.priority	= NF_IP_PRI_FILTER,	},	{		.hook		= ipt_hook,		.owner		= THIS_MODULE,		.pf		= PF_INET,		.hooknum	= NF_IP_FORWARD,		.priority	= NF_IP_PRI_FILTER,	},	{		.hook		= ipt_local_out_hook,		.owner		= THIS_MODULE,		.pf		= PF_INET,		.hooknum	= NF_IP_LOCAL_OUT,		.priority	= NF_IP_PRI_FILTER,	},};/* Default to forward because I got too much mail already. */static int forward = NF_ACCEPT;MODULE_PARM(forward, "i");static int __init init(void){	int ret;	if (forward < 0 || forward > NF_MAX_VERDICT) {		printk("iptables forward must be 0 or 1\n");		return -EINVAL;	}	/* Entry 1 is the FORWARD hook */	initial_table.entries[1].target.verdict = -forward - 1;	/* Register table */	ret = ipt_register_table(&packet_filter);	if (ret < 0)		return ret;	/* Register hooks */	ret = nf_register_hook(&ipt_ops[0]);	if (ret < 0)		goto cleanup_table;	ret = nf_register_hook(&ipt_ops[1]);	if (ret < 0)		goto cleanup_hook0;	ret = nf_register_hook(&ipt_ops[2]);	if (ret < 0)		goto cleanup_hook1;	return ret; cleanup_hook1:	nf_unregister_hook(&ipt_ops[1]); cleanup_hook0:	nf_unregister_hook(&ipt_ops[0]); cleanup_table:	ipt_unregister_table(&packet_filter);	return ret;}static void __exit fini(void){	unsigned int i;	for (i = 0; i < sizeof(ipt_ops)/sizeof(struct nf_hook_ops); i++)		nf_unregister_hook(&ipt_ops[i]);	ipt_unregister_table(&packet_filter);}module_init(init);module_exit(fini);