text: /*
   * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
   *
   * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
   */
  #include <linux/module.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))
  
  /* Standard entry. */
  struct ip6t_standard
  {
  	struct ip6t_entry entry;
  	struct ip6t_standard_target target;
  };
  
  struct ip6t_error_target
  {
  	struct ip6t_entry_target target;
  	char errorname[IP6T_FUNCTION_MAXNAMELEN];
  };
  
  struct ip6t_error
  {
  	struct ip6t_entry entry;
  	struct ip6t_error_target target;
  };
  
  static struct
  {
  	struct ip6t_replace repl;
  	struct ip6t_standard entries[3];
  	struct ip6t_error term;
  } initial_table __initdata
  = { { "filter", FILTER_VALID_HOOKS, 4,
        sizeof(struct ip6t_standard) * 3 + sizeof(struct ip6t_error),
        { [NF_IP6_LOCAL_IN] = 0,
  	[NF_IP6_FORWARD] = sizeof(struct ip6t_standard),
  	[NF_IP6_LOCAL_OUT] = sizeof(struct ip6t_standard) * 2 },
        { [NF_IP6_LOCAL_IN] = 0,
  	[NF_IP6_FORWARD] = sizeof(struct ip6t_standard),
  	[NF_IP6_LOCAL_OUT] = sizeof(struct ip6t_standard) * 2 },
        0, NULL, { } },
      {
  	    /* LOCAL_IN */
  	    { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  		0,
  		sizeof(struct ip6t_entry),
  		sizeof(struct ip6t_standard),
  		0, { 0, 0 }, { } },
  	      { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
  		-NF_ACCEPT - 1 } },
  	    /* FORWARD */
  	    { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  		0,
  		sizeof(struct ip6t_entry),
  		sizeof(struct ip6t_standard),
  		0, { 0, 0 }, { } },
  	      { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
  		-NF_ACCEPT - 1 } },
  	    /* LOCAL_OUT */
  	    { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  		0,
  		sizeof(struct ip6t_entry),
  		sizeof(struct ip6t_standard),
  		0, { 0, 0 }, { } },
  	      { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
  		-NF_ACCEPT - 1 } }
      },
      /* ERROR */
      { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  	0,
  	sizeof(struct ip6t_entry),
  	sizeof(struct ip6t_error),
  	0, { 0, 0 }, { } },
        { { { { IP6T_ALIGN(sizeof(struct ip6t_error_target)), IP6T_ERROR_TARGET } },
  	  { } },
  	"ERROR"
        }
      }
  };
  
  static struct ip6t_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 int
  ip6t_hook(unsigned int hook,
  	 struct sk_buff **pskb,
  	 const struct net_device *in,
  	 const struct net_device *out,
  	 int (*okfn)(struct sk_buff *))
  {
  	return ip6t_do_table(pskb, hook, in, out, &packet_filter, NULL);
  }
  
  static unsigned int
  ip6t_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 *))
  {
  #if 0
  	/* root is playing with raw sockets. */
  	if ((*pskb)->len < sizeof(struct iphdr)
  	    || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr)) {
  		if (net_ratelimit())
  			printk("ip6t_hook: happy cracking.\n");
  		return NF_ACCEPT;
  	}
  #endif
  
  	return ip6t_do_table(pskb, hook, in, out, &packet_filter, NULL);
  }
  
  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_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 = ip6t_register_table(&packet_filter);
  	if (ret < 0)
  		return ret;
  
  	/* Register hooks */
  	ret = nf_register_hook(&ip6t_ops[0]);
  	if (ret < 0)
  		goto cleanup_table;
  
  	ret = nf_register_hook(&ip6t_ops[1]);
  	if (ret < 0)
  		goto cleanup_hook0;
  
  	ret = nf_register_hook(&ip6t_ops[2]);
  	if (ret < 0)
  		goto cleanup_hook1;
  
  	return ret;
  
   cleanup_hook1:
  	nf_unregister_hook(&ip6t_ops[1]);
   cleanup_hook0:
  	nf_unregister_hook(&ip6t_ops[0]);
   cleanup_table:
  	ip6t_unregister_table(&packet_filter);
  
  	return ret;
  }
  
  static void __exit fini(void)
  {
  	unsigned int i;
  
  	for (i = 0; i < sizeof(ip6t_ops)/sizeof(struct nf_hook_ops); i++)
  		nf_unregister_hook(&ip6t_ops[i]);
  
  	ip6t_unregister_table(&packet_filter);
  }
  
  module_init(init);
  module_exit(fini);
  