text: /*
   * 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_ipv6/ip6_tables.h>
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  MODULE_DESCRIPTION("ip6tables filter table");
  
  #define FILTER_VALID_HOOKS ((1 << NF_IP6_LOCAL_IN) | (1 << NF_IP6_FORWARD) | (1 << NF_IP6_LOCAL_OUT))
  
  static struct
  {
  	struct ip6t_replace repl;
  	struct ip6t_standard entries[3];
  	struct ip6t_error term;
  } initial_table __initdata = {
  	.repl = {
  		.name = "filter",
  		.valid_hooks = FILTER_VALID_HOOKS,
  		.num_entries = 4,
  		.size = sizeof(struct ip6t_standard) * 3 + sizeof(struct ip6t_error),
  		.hook_entry = {
  			[NF_IP6_LOCAL_IN] = 0,
  			[NF_IP6_FORWARD] = sizeof(struct ip6t_standard),
  			[NF_IP6_LOCAL_OUT] = sizeof(struct ip6t_standard) * 2
  		},
  		.underflow = {
  			[NF_IP6_LOCAL_IN] = 0,
  			[NF_IP6_FORWARD] = sizeof(struct ip6t_standard),
  			[NF_IP6_LOCAL_OUT] = sizeof(struct ip6t_standard) * 2
  		},
  	},
  	.entries = {
  		IP6T_STANDARD_INIT(NF_ACCEPT),	/* LOCAL_IN */
  		IP6T_STANDARD_INIT(NF_ACCEPT),	/* FORWARD */
  		IP6T_STANDARD_INIT(NF_ACCEPT),	/* LOCAL_OUT */
  	},
  	.term = IP6T_ERROR_INIT,		/* ERROR */
  };
  
  static struct xt_table packet_filter = {
  	.name		= "filter",
  	.valid_hooks	= FILTER_VALID_HOOKS,
  	.me		= THIS_MODULE,
  	.af		= AF_INET6,
  };
  
  /* The work comes in here from netfilter.c. */
  static unsigned int
  ip6t_hook(unsigned int hook,
  	 struct sk_buff *skb,
  	 const struct net_device *in,
  	 const struct net_device *out,
  	 int (*okfn)(struct sk_buff *))
  {
  	return ip6t_do_table(skb, hook, in, out, &packet_filter);
  }
  
  static unsigned int
  ip6t_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 *))
  {
  #if 0
  	/* root is playing with raw sockets. */
  	if (skb->len < sizeof(struct iphdr)
  	    || ip_hdrlen(skb) < sizeof(struct iphdr)) {
  		if (net_ratelimit())
  			printk("ip6t_hook: happy cracking.\n");
  		return NF_ACCEPT;
  	}
  #endif
  
  	return ip6t_do_table(skb, hook, in, out, &packet_filter);
  }
  
  static struct nf_hook_ops ip6t_ops[] = {
  	{
  		.hook		= ip6t_hook,
  		.owner		= THIS_MODULE,
  		.pf		= PF_INET6,
  		.hooknum	= NF_IP6_LOCAL_IN,
  		.priority	= NF_IP6_PRI_FILTER,
  	},
  	{
  		.hook		= ip6t_hook,
  		.owner		= THIS_MODULE,
  		.pf		= PF_INET6,
  		.hooknum	= NF_IP6_FORWARD,
  		.priority	= NF_IP6_PRI_FILTER,
  	},
  	{
  		.hook		= ip6t_local_out_hook,
  		.owner		= THIS_MODULE,
  		.pf		= PF_INET6,
  		.hooknum	= NF_IP6_LOCAL_OUT,
  		.priority	= NF_IP6_PRI_FILTER,
  	},
  };
  
  /* Default to forward because I got too much mail already. */
  static int forward = NF_ACCEPT;
  module_param(forward, bool, 0000);
  
  static int __init ip6table_filter_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 = ip6t_register_table(&packet_filter, &initial_table.repl);
  	if (ret < 0)
  		return ret;
  
  	/* Register hooks */
  	ret = nf_register_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
  	if (ret < 0)
  		goto cleanup_table;
  
  	return ret;
  
   cleanup_table:
  	ip6t_unregister_table(&packet_filter);
  	return ret;
  }
  
  static void __exit ip6table_filter_fini(void)
  {
  	nf_unregister_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
  	ip6t_unregister_table(&packet_filter);
  }
  
  module_init(ip6table_filter_init);
  module_exit(ip6table_filter_fini);
  