// SPDX-License-Identifier: GPL-2.0-only

  /*
   * (C) 1999-2001 Paul `Rusty' Russell
   * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
   * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
   *

   * Based on Rusty Russell's IPv4 REDIRECT target. Development of IPv6
   * NAT funded by Astaro.
   */
  
  #include <linux/if.h>
  #include <linux/inetdevice.h>
  #include <linux/ip.h>
  #include <linux/kernel.h>

  #include <linux/netdevice.h>
  #include <linux/netfilter.h>
  #include <linux/types.h>
  #include <linux/netfilter_ipv4.h>

  #include <linux/netfilter_ipv6.h>

  #include <linux/netfilter/x_tables.h>
  #include <net/addrconf.h>
  #include <net/checksum.h>
  #include <net/protocol.h>
  #include <net/netfilter/nf_nat.h>

  #include <net/netfilter/nf_nat_redirect.h>

  
  unsigned int
  nf_nat_redirect_ipv4(struct sk_buff *skb,
  		     const struct nf_nat_ipv4_multi_range_compat *mr,
  		     unsigned int hooknum)
  {
  	struct nf_conn *ct;
  	enum ip_conntrack_info ctinfo;
  	__be32 newdst;

  	struct nf_nat_range2 newrange;

  	WARN_ON(hooknum != NF_INET_PRE_ROUTING &&
  		hooknum != NF_INET_LOCAL_OUT);

  
  	ct = nf_ct_get(skb, &ctinfo);

  	WARN_ON(!(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED)));

  
  	/* Local packets: make them go to loopback */
  	if (hooknum == NF_INET_LOCAL_OUT) {
  		newdst = htonl(0x7F000001);
  	} else {

  		const struct in_device *indev;

  
  		newdst = 0;

  		indev = __in_dev_get_rcu(skb->dev);

  		if (indev) {
  			const struct in_ifaddr *ifa;
  
  			ifa = rcu_dereference(indev->ifa_list);
  			if (ifa)
  				newdst = ifa->ifa_local;

  		}

  
  		if (!newdst)
  			return NF_DROP;
  	}
  
  	/* Transfer from original range. */
  	memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
  	memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
  	newrange.flags	     = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
  	newrange.min_addr.ip = newdst;
  	newrange.max_addr.ip = newdst;
  	newrange.min_proto   = mr->range[0].min;
  	newrange.max_proto   = mr->range[0].max;
  
  	/* Hand modified range to generic setup. */
  	return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST);
  }
  EXPORT_SYMBOL_GPL(nf_nat_redirect_ipv4);

  static const struct in6_addr loopback_addr = IN6ADDR_LOOPBACK_INIT;
  
  unsigned int

  nf_nat_redirect_ipv6(struct sk_buff *skb, const struct nf_nat_range2 *range,

  		     unsigned int hooknum)
  {

  	struct nf_nat_range2 newrange;

  	struct in6_addr newdst;
  	enum ip_conntrack_info ctinfo;
  	struct nf_conn *ct;
  
  	ct = nf_ct_get(skb, &ctinfo);
  	if (hooknum == NF_INET_LOCAL_OUT) {
  		newdst = loopback_addr;
  	} else {
  		struct inet6_dev *idev;
  		struct inet6_ifaddr *ifa;
  		bool addr = false;

  		idev = __in6_dev_get(skb->dev);
  		if (idev != NULL) {

  			read_lock_bh(&idev->lock);

  			list_for_each_entry(ifa, &idev->addr_list, if_list) {
  				newdst = ifa->addr;
  				addr = true;
  				break;
  			}

  			read_unlock_bh(&idev->lock);

  		}

  
  		if (!addr)
  			return NF_DROP;
  	}
  
  	newrange.flags		= range->flags | NF_NAT_RANGE_MAP_IPS;
  	newrange.min_addr.in6	= newdst;
  	newrange.max_addr.in6	= newdst;
  	newrange.min_proto	= range->min_proto;
  	newrange.max_proto	= range->max_proto;
  
  	return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST);
  }
  EXPORT_SYMBOL_GPL(nf_nat_redirect_ipv6);