/*

   *	IPv6 tunneling device

   *	Linux INET6 implementation
   *
   *	Authors:

   *	Ville Nuorvala		<vnuorval@tcs.hut.fi>

   *	Yasuyuki Kozakai	<kozakai@linux-ipv6.org>

   *

   *      Based on:

   *      linux/net/ipv6/sit.c and linux/net/ipv4/ipip.c

   *
   *      RFC 2473
   *
   *	This program is free software; you can redistribute it and/or
   *      modify it under the terms of the GNU General Public License
   *      as published by the Free Software Foundation; either version
   *      2 of the License, or (at your option) any later version.
   *
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/module.h>

  #include <linux/capability.h>

  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/sockios.h>

  #include <linux/icmp.h>

  #include <linux/if.h>
  #include <linux/in.h>
  #include <linux/ip.h>
  #include <linux/if_tunnel.h>
  #include <linux/net.h>
  #include <linux/in6.h>
  #include <linux/netdevice.h>
  #include <linux/if_arp.h>
  #include <linux/icmpv6.h>
  #include <linux/init.h>
  #include <linux/route.h>
  #include <linux/rtnetlink.h>
  #include <linux/netfilter_ipv6.h>

  #include <linux/slab.h>

  #include <linux/hash.h>

  
  #include <asm/uaccess.h>

  #include <linux/atomic.h>

  #include <net/icmp.h>

  #include <net/ip.h>

  #include <net/ip_tunnels.h>

  #include <net/ipv6.h>

  #include <net/ip6_route.h>
  #include <net/addrconf.h>
  #include <net/ip6_tunnel.h>
  #include <net/xfrm.h>
  #include <net/dsfield.h>
  #include <net/inet_ecn.h>

  #include <net/net_namespace.h>
  #include <net/netns/generic.h>

  
  MODULE_AUTHOR("Ville Nuorvala");

  MODULE_DESCRIPTION("IPv6 tunneling device");

  MODULE_LICENSE("GPL");

  MODULE_ALIAS_NETDEV("ip6tnl0");

  #ifdef IP6_TNL_DEBUG

  #define IP6_TNL_TRACE(x...) pr_debug("%s:" x "
  ", __func__)

  #else
  #define IP6_TNL_TRACE(x...) do {;} while(0)
  #endif
  
  #define IPV6_TCLASS_MASK (IPV6_FLOWINFO_MASK & ~IPV6_FLOWLABEL_MASK)

  #define IPV6_TCLASS_SHIFT 20

  #define HASH_SIZE_SHIFT  5
  #define HASH_SIZE (1 << HASH_SIZE_SHIFT)

  static bool log_ecn_error = true;
  module_param(log_ecn_error, bool, 0644);
  MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN");

  static u32 HASH(const struct in6_addr *addr1, const struct in6_addr *addr2)
  {
  	u32 hash = ipv6_addr_hash(addr1) ^ ipv6_addr_hash(addr2);
  
  	return hash_32(hash, HASH_SIZE_SHIFT);
  }

  static int ip6_tnl_dev_init(struct net_device *dev);

  static void ip6_tnl_dev_setup(struct net_device *dev);

  static struct rtnl_link_ops ip6_link_ops __read_mostly;

  static int ip6_tnl_net_id __read_mostly;

  struct ip6_tnl_net {

  	/* the IPv6 tunnel fallback device */
  	struct net_device *fb_tnl_dev;

  	/* lists for storing tunnels in use */

  	struct ip6_tnl __rcu *tnls_r_l[HASH_SIZE];
  	struct ip6_tnl __rcu *tnls_wc[1];
  	struct ip6_tnl __rcu **tnls[2];

  };

  static struct net_device_stats *ip6_get_stats(struct net_device *dev)
  {
  	struct pcpu_tstats sum = { 0 };
  	int i;
  
  	for_each_possible_cpu(i) {
  		const struct pcpu_tstats *tstats = per_cpu_ptr(dev->tstats, i);
  
  		sum.rx_packets += tstats->rx_packets;
  		sum.rx_bytes   += tstats->rx_bytes;
  		sum.tx_packets += tstats->tx_packets;
  		sum.tx_bytes   += tstats->tx_bytes;
  	}
  	dev->stats.rx_packets = sum.rx_packets;
  	dev->stats.rx_bytes   = sum.rx_bytes;
  	dev->stats.tx_packets = sum.tx_packets;
  	dev->stats.tx_bytes   = sum.tx_bytes;
  	return &dev->stats;
  }

  /*

   * Locking : hash tables are protected by RCU and RTNL

   */

  struct dst_entry *ip6_tnl_dst_check(struct ip6_tnl *t)

  {
  	struct dst_entry *dst = t->dst_cache;

  	if (dst && dst->obsolete &&

  	    dst->ops->check(dst, t->dst_cookie) == NULL) {
  		t->dst_cache = NULL;
  		dst_release(dst);
  		return NULL;
  	}
  
  	return dst;
  }

  EXPORT_SYMBOL_GPL(ip6_tnl_dst_check);

  void ip6_tnl_dst_reset(struct ip6_tnl *t)

  {
  	dst_release(t->dst_cache);
  	t->dst_cache = NULL;
  }

  EXPORT_SYMBOL_GPL(ip6_tnl_dst_reset);

  void ip6_tnl_dst_store(struct ip6_tnl *t, struct dst_entry *dst)

  {
  	struct rt6_info *rt = (struct rt6_info *) dst;
  	t->dst_cookie = rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0;
  	dst_release(t->dst_cache);
  	t->dst_cache = dst;
  }

  EXPORT_SYMBOL_GPL(ip6_tnl_dst_store);

  
  /**

   * ip6_tnl_lookup - fetch tunnel matching the end-point addresses

   *   @remote: the address of the tunnel exit-point
   *   @local: the address of the tunnel entry-point

   *

   * Return:

   *   tunnel matching given end-points if found,

   *   else fallback tunnel if its device is up,

   *   else %NULL
   **/

  #define for_each_ip6_tunnel_rcu(start) \
  	for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))

  static struct ip6_tnl *

  ip6_tnl_lookup(struct net *net, const struct in6_addr *remote, const struct in6_addr *local)

  {

  	unsigned int hash = HASH(remote, local);

  	struct ip6_tnl *t;

  	struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);

  	for_each_ip6_tunnel_rcu(ip6n->tnls_r_l[hash]) {

  		if (ipv6_addr_equal(local, &t->parms.laddr) &&
  		    ipv6_addr_equal(remote, &t->parms.raddr) &&
  		    (t->dev->flags & IFF_UP))
  			return t;
  	}

  	t = rcu_dereference(ip6n->tnls_wc[0]);
  	if (t && (t->dev->flags & IFF_UP))

  		return t;
  
  	return NULL;
  }
  
  /**

   * ip6_tnl_bucket - get head of list matching given tunnel parameters

   *   @p: parameters containing tunnel end-points

   *
   * Description:

   *   ip6_tnl_bucket() returns the head of the list matching the

   *   &struct in6_addr entries laddr and raddr in @p.
   *

   * Return: head of IPv6 tunnel list

   **/

  static struct ip6_tnl __rcu **

  ip6_tnl_bucket(struct ip6_tnl_net *ip6n, const struct __ip6_tnl_parm *p)

  {

  	const struct in6_addr *remote = &p->raddr;
  	const struct in6_addr *local = &p->laddr;

  	unsigned int h = 0;

  	int prio = 0;
  
  	if (!ipv6_addr_any(remote) || !ipv6_addr_any(local)) {
  		prio = 1;

  		h = HASH(remote, local);

  	}

  	return &ip6n->tnls[prio][h];

  }
  
  /**

   * ip6_tnl_link - add tunnel to hash table

   *   @t: tunnel to be added
   **/
  
  static void

  ip6_tnl_link(struct ip6_tnl_net *ip6n, struct ip6_tnl *t)

  {

  	struct ip6_tnl __rcu **tp = ip6_tnl_bucket(ip6n, &t->parms);

  	rcu_assign_pointer(t->next , rtnl_dereference(*tp));
  	rcu_assign_pointer(*tp, t);

  }
  
  /**

   * ip6_tnl_unlink - remove tunnel from hash table

   *   @t: tunnel to be removed
   **/
  
  static void

  ip6_tnl_unlink(struct ip6_tnl_net *ip6n, struct ip6_tnl *t)

  {

  	struct ip6_tnl __rcu **tp;
  	struct ip6_tnl *iter;
  
  	for (tp = ip6_tnl_bucket(ip6n, &t->parms);
  	     (iter = rtnl_dereference(*tp)) != NULL;
  	     tp = &iter->next) {
  		if (t == iter) {

  			rcu_assign_pointer(*tp, t->next);

  			break;
  		}
  	}
  }

  static void ip6_dev_free(struct net_device *dev)
  {
  	free_percpu(dev->tstats);
  	free_netdev(dev);
  }

  static int ip6_tnl_create2(struct net_device *dev)
  {
  	struct ip6_tnl *t = netdev_priv(dev);
  	struct net *net = dev_net(dev);
  	struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);
  	int err;
  
  	t = netdev_priv(dev);
  	err = ip6_tnl_dev_init(dev);
  	if (err < 0)
  		goto out;
  
  	err = register_netdevice(dev);
  	if (err < 0)
  		goto out;
  
  	strcpy(t->parms.name, dev->name);
  	dev->rtnl_link_ops = &ip6_link_ops;
  
  	dev_hold(dev);
  	ip6_tnl_link(ip6n, t);
  	return 0;
  
  out:
  	return err;
  }

  /**

   * ip6_tnl_create - create a new tunnel

   *   @p: tunnel parameters
   *   @pt: pointer to new tunnel
   *
   * Description:
   *   Create tunnel matching given parameters.

   *
   * Return:

   *   created tunnel or NULL

   **/

  static struct ip6_tnl *ip6_tnl_create(struct net *net, struct __ip6_tnl_parm *p)

  {
  	struct net_device *dev;
  	struct ip6_tnl *t;
  	char name[IFNAMSIZ];
  	int err;

  	if (p->name[0])

  		strlcpy(name, p->name, IFNAMSIZ);

  	else
  		sprintf(name, "ip6tnl%%d");

  	dev = alloc_netdev(sizeof (*t), name, ip6_tnl_dev_setup);

  	if (dev == NULL)

  		goto failed;

  	dev_net_set(dev, net);

  	t = netdev_priv(dev);

  	t->parms = *p;

  	err = ip6_tnl_create2(dev);

  	if (err < 0)
  		goto failed_free;

  	return t;

  
  failed_free:

  	ip6_dev_free(dev);

  failed:
  	return NULL;

  }
  
  /**

   * ip6_tnl_locate - find or create tunnel matching given parameters

   *   @p: tunnel parameters

   *   @create: != 0 if allowed to create new tunnel if no match found
   *
   * Description:

   *   ip6_tnl_locate() first tries to locate an existing tunnel

   *   based on @parms. If this is unsuccessful, but @create is set a new
   *   tunnel device is created and registered for use.
   *
   * Return:

   *   matching tunnel or NULL

   **/

  static struct ip6_tnl *ip6_tnl_locate(struct net *net,

  		struct __ip6_tnl_parm *p, int create)

  {

  	const struct in6_addr *remote = &p->raddr;
  	const struct in6_addr *local = &p->laddr;

  	struct ip6_tnl __rcu **tp;

  	struct ip6_tnl *t;

  	struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);

  	for (tp = ip6_tnl_bucket(ip6n, p);
  	     (t = rtnl_dereference(*tp)) != NULL;
  	     tp = &t->next) {

  		if (ipv6_addr_equal(local, &t->parms.laddr) &&

  		    ipv6_addr_equal(remote, &t->parms.raddr))
  			return t;

  	}
  	if (!create)

  		return NULL;

  	return ip6_tnl_create(net, p);

  }
  
  /**

   * ip6_tnl_dev_uninit - tunnel device uninitializer

   *   @dev: the device to be destroyed

   *

   * Description:

   *   ip6_tnl_dev_uninit() removes tunnel from its list

   **/
  
  static void

  ip6_tnl_dev_uninit(struct net_device *dev)

  {

  	struct ip6_tnl *t = netdev_priv(dev);

  	struct net *net = dev_net(dev);
  	struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);

  	if (dev == ip6n->fb_tnl_dev)

  		RCU_INIT_POINTER(ip6n->tnls_wc[0], NULL);

  	else

  		ip6_tnl_unlink(ip6n, t);

  	ip6_tnl_dst_reset(t);
  	dev_put(dev);
  }
  
  /**
   * parse_tvl_tnl_enc_lim - handle encapsulation limit option
   *   @skb: received socket buffer
   *

   * Return:
   *   0 if none was found,

   *   else index to encapsulation limit
   **/

  __u16 ip6_tnl_parse_tlv_enc_lim(struct sk_buff *skb, __u8 *raw)

  {

  	const struct ipv6hdr *ipv6h = (const struct ipv6hdr *) raw;

  	__u8 nexthdr = ipv6h->nexthdr;
  	__u16 off = sizeof (*ipv6h);
  
  	while (ipv6_ext_hdr(nexthdr) && nexthdr != NEXTHDR_NONE) {
  		__u16 optlen = 0;
  		struct ipv6_opt_hdr *hdr;
  		if (raw + off + sizeof (*hdr) > skb->data &&
  		    !pskb_may_pull(skb, raw - skb->data + off + sizeof (*hdr)))
  			break;
  
  		hdr = (struct ipv6_opt_hdr *) (raw + off);
  		if (nexthdr == NEXTHDR_FRAGMENT) {
  			struct frag_hdr *frag_hdr = (struct frag_hdr *) hdr;
  			if (frag_hdr->frag_off)
  				break;
  			optlen = 8;
  		} else if (nexthdr == NEXTHDR_AUTH) {
  			optlen = (hdr->hdrlen + 2) << 2;
  		} else {
  			optlen = ipv6_optlen(hdr);
  		}
  		if (nexthdr == NEXTHDR_DEST) {
  			__u16 i = off + 2;
  			while (1) {
  				struct ipv6_tlv_tnl_enc_lim *tel;
  
  				/* No more room for encapsulation limit */
  				if (i + sizeof (*tel) > off + optlen)
  					break;
  
  				tel = (struct ipv6_tlv_tnl_enc_lim *) &raw[i];
  				/* return index of option if found and valid */
  				if (tel->type == IPV6_TLV_TNL_ENCAP_LIMIT &&
  				    tel->length == 1)
  					return i;
  				/* else jump to next option */
  				if (tel->type)
  					i += tel->length + 2;
  				else
  					i++;
  			}
  		}
  		nexthdr = hdr->nexthdr;
  		off += optlen;
  	}
  	return 0;
  }

  EXPORT_SYMBOL(ip6_tnl_parse_tlv_enc_lim);

  
  /**

   * ip6_tnl_err - tunnel error handler

   *
   * Description:

   *   ip6_tnl_err() should handle errors in the tunnel according

   *   to the specifications in RFC 2473.
   **/

  static int

  ip6_tnl_err(struct sk_buff *skb, __u8 ipproto, struct inet6_skb_parm *opt,

  	    u8 *type, u8 *code, int *msg, __u32 *info, int offset)

  {

  	const struct ipv6hdr *ipv6h = (const struct ipv6hdr *) skb->data;

  	struct ip6_tnl *t;
  	int rel_msg = 0;

  	u8 rel_type = ICMPV6_DEST_UNREACH;
  	u8 rel_code = ICMPV6_ADDR_UNREACH;

  	__u32 rel_info = 0;
  	__u16 len;

  	int err = -ENOENT;

  	/* If the packet doesn't contain the original IPv6 header we are
  	   in trouble since we might need the source address for further

  	   processing of the error. */

  	rcu_read_lock();

  	if ((t = ip6_tnl_lookup(dev_net(skb->dev), &ipv6h->daddr,

  					&ipv6h->saddr)) == NULL)

  		goto out;

  	if (t->parms.proto != ipproto && t->parms.proto != 0)
  		goto out;

  	err = 0;

  	switch (*type) {

  		__u32 teli;
  		struct ipv6_tlv_tnl_enc_lim *tel;
  		__u32 mtu;
  	case ICMPV6_DEST_UNREACH:

  		net_warn_ratelimited("%s: Path to destination invalid or inactive!
  ",
  				     t->parms.name);

  		rel_msg = 1;
  		break;
  	case ICMPV6_TIME_EXCEED:

  		if ((*code) == ICMPV6_EXC_HOPLIMIT) {

  			net_warn_ratelimited("%s: Too small hop limit or routing loop in tunnel!
  ",
  					     t->parms.name);

  			rel_msg = 1;
  		}
  		break;
  	case ICMPV6_PARAMPROB:

  		teli = 0;

  		if ((*code) == ICMPV6_HDR_FIELD)

  			teli = ip6_tnl_parse_tlv_enc_lim(skb, skb->data);

  		if (teli && teli == *info - 2) {

  			tel = (struct ipv6_tlv_tnl_enc_lim *) &skb->data[teli];
  			if (tel->encap_limit == 0) {

  				net_warn_ratelimited("%s: Too small encapsulation limit or routing loop in tunnel!
  ",
  						     t->parms.name);

  				rel_msg = 1;
  			}

  		} else {
  			net_warn_ratelimited("%s: Recipient unable to parse tunneled packet!
  ",
  					     t->parms.name);

  		}
  		break;
  	case ICMPV6_PKT_TOOBIG:

  		mtu = *info - offset;

  		if (mtu < IPV6_MIN_MTU)
  			mtu = IPV6_MIN_MTU;
  		t->dev->mtu = mtu;

  		if ((len = sizeof (*ipv6h) + ntohs(ipv6h->payload_len)) > mtu) {

  			rel_type = ICMPV6_PKT_TOOBIG;
  			rel_code = 0;
  			rel_info = mtu;
  			rel_msg = 1;
  		}
  		break;
  	}

  
  	*type = rel_type;
  	*code = rel_code;
  	*info = rel_info;
  	*msg = rel_msg;
  
  out:

  	rcu_read_unlock();

  	return err;
  }
  
  static int

  ip4ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,

  	   u8 type, u8 code, int offset, __be32 info)

  {
  	int rel_msg = 0;

  	u8 rel_type = type;
  	u8 rel_code = code;

  	__u32 rel_info = ntohl(info);

  	int err;
  	struct sk_buff *skb2;

  	const struct iphdr *eiph;

  	struct rtable *rt;

  	struct flowi4 fl4;

  	err = ip6_tnl_err(skb, IPPROTO_IPIP, opt, &rel_type, &rel_code,
  			  &rel_msg, &rel_info, offset);

  	if (err < 0)
  		return err;
  
  	if (rel_msg == 0)
  		return 0;
  
  	switch (rel_type) {
  	case ICMPV6_DEST_UNREACH:
  		if (rel_code != ICMPV6_ADDR_UNREACH)
  			return 0;
  		rel_type = ICMP_DEST_UNREACH;
  		rel_code = ICMP_HOST_UNREACH;
  		break;
  	case ICMPV6_PKT_TOOBIG:
  		if (rel_code != 0)
  			return 0;
  		rel_type = ICMP_DEST_UNREACH;
  		rel_code = ICMP_FRAG_NEEDED;
  		break;

  	case NDISC_REDIRECT:
  		rel_type = ICMP_REDIRECT;
  		rel_code = ICMP_REDIR_HOST;

  	default:
  		return 0;
  	}
  
  	if (!pskb_may_pull(skb, offset + sizeof(struct iphdr)))
  		return 0;
  
  	skb2 = skb_clone(skb, GFP_ATOMIC);
  	if (!skb2)
  		return 0;

  	skb_dst_drop(skb2);

  	skb_pull(skb2, offset);

  	skb_reset_network_header(skb2);

  	eiph = ip_hdr(skb2);

  
  	/* Try to guess incoming interface */

  	rt = ip_route_output_ports(dev_net(skb->dev), &fl4, NULL,

  				   eiph->saddr, 0,
  				   0, 0,
  				   IPPROTO_IPIP, RT_TOS(eiph->tos), 0);

  	if (IS_ERR(rt))

  		goto out;

  	skb2->dev = rt->dst.dev;

  
  	/* route "incoming" packet */
  	if (rt->rt_flags & RTCF_LOCAL) {
  		ip_rt_put(rt);
  		rt = NULL;

  		rt = ip_route_output_ports(dev_net(skb->dev), &fl4, NULL,

  					   eiph->daddr, eiph->saddr,
  					   0, 0,
  					   IPPROTO_IPIP,
  					   RT_TOS(eiph->tos), 0);

  		if (IS_ERR(rt) ||

  		    rt->dst.dev->type != ARPHRD_TUNNEL) {

  			if (!IS_ERR(rt))
  				ip_rt_put(rt);

  			goto out;
  		}

  		skb_dst_set(skb2, &rt->dst);

  	} else {
  		ip_rt_put(rt);
  		if (ip_route_input(skb2, eiph->daddr, eiph->saddr, eiph->tos,
  				   skb2->dev) ||

  		    skb_dst(skb2)->dev->type != ARPHRD_TUNNEL)

  			goto out;
  	}
  
  	/* change mtu on this route */
  	if (rel_type == ICMP_DEST_UNREACH && rel_code == ICMP_FRAG_NEEDED) {

  		if (rel_info > dst_mtu(skb_dst(skb2)))

  			goto out;

  		skb_dst(skb2)->ops->update_pmtu(skb_dst(skb2), NULL, skb2, rel_info);

  	}

  	if (rel_type == ICMP_REDIRECT)

  		skb_dst(skb2)->ops->redirect(skb_dst(skb2), NULL, skb2);

  	icmp_send(skb2, rel_type, rel_code, htonl(rel_info));

  
  out:
  	kfree_skb(skb2);
  	return 0;
  }
  
  static int

  ip6ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,

  	   u8 type, u8 code, int offset, __be32 info)

  {
  	int rel_msg = 0;

  	u8 rel_type = type;
  	u8 rel_code = code;

  	__u32 rel_info = ntohl(info);

  	int err;

  	err = ip6_tnl_err(skb, IPPROTO_IPV6, opt, &rel_type, &rel_code,
  			  &rel_msg, &rel_info, offset);

  	if (err < 0)
  		return err;
  
  	if (rel_msg && pskb_may_pull(skb, offset + sizeof(struct ipv6hdr))) {

  		struct rt6_info *rt;
  		struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);

  		if (!skb2)

  			return 0;

  		skb_dst_drop(skb2);

  		skb_pull(skb2, offset);

  		skb_reset_network_header(skb2);

  
  		/* Try to guess incoming interface */

  		rt = rt6_lookup(dev_net(skb->dev), &ipv6_hdr(skb2)->saddr,
  				NULL, 0, 0);

  		if (rt && rt->dst.dev)
  			skb2->dev = rt->dst.dev;

  		icmpv6_send(skb2, rel_type, rel_code, rel_info);

  		ip6_rt_put(rt);

  
  		kfree_skb(skb2);
  	}

  
  	return 0;

  }

  static int ip4ip6_dscp_ecn_decapsulate(const struct ip6_tnl *t,
  				       const struct ipv6hdr *ipv6h,
  				       struct sk_buff *skb)

  {
  	__u8 dsfield = ipv6_get_dsfield(ipv6h) & ~INET_ECN_MASK;
  
  	if (t->parms.flags & IP6_TNL_F_RCV_DSCP_COPY)

  		ipv4_change_dsfield(ip_hdr(skb), INET_ECN_MASK, dsfield);

  	return IP6_ECN_decapsulate(ipv6h, skb);

  }

  static int ip6ip6_dscp_ecn_decapsulate(const struct ip6_tnl *t,
  				       const struct ipv6hdr *ipv6h,
  				       struct sk_buff *skb)

  {

  	if (t->parms.flags & IP6_TNL_F_RCV_DSCP_COPY)

  		ipv6_copy_dscp(ipv6_get_dsfield(ipv6h), ipv6_hdr(skb));

  	return IP6_ECN_decapsulate(ipv6h, skb);

  }

  __u32 ip6_tnl_get_cap(struct ip6_tnl *t,

  			     const struct in6_addr *laddr,
  			     const struct in6_addr *raddr)
  {

  	struct __ip6_tnl_parm *p = &t->parms;

  	int ltype = ipv6_addr_type(laddr);
  	int rtype = ipv6_addr_type(raddr);
  	__u32 flags = 0;
  
  	if (ltype == IPV6_ADDR_ANY || rtype == IPV6_ADDR_ANY) {
  		flags = IP6_TNL_F_CAP_PER_PACKET;
  	} else if (ltype & (IPV6_ADDR_UNICAST|IPV6_ADDR_MULTICAST) &&
  		   rtype & (IPV6_ADDR_UNICAST|IPV6_ADDR_MULTICAST) &&
  		   !((ltype|rtype) & IPV6_ADDR_LOOPBACK) &&
  		   (!((ltype|rtype) & IPV6_ADDR_LINKLOCAL) || p->link)) {
  		if (ltype&IPV6_ADDR_UNICAST)
  			flags |= IP6_TNL_F_CAP_XMIT;
  		if (rtype&IPV6_ADDR_UNICAST)
  			flags |= IP6_TNL_F_CAP_RCV;
  	}
  	return flags;
  }

  EXPORT_SYMBOL(ip6_tnl_get_cap);

  /* called with rcu_read_lock() */

  int ip6_tnl_rcv_ctl(struct ip6_tnl *t,

  				  const struct in6_addr *laddr,
  				  const struct in6_addr *raddr)

  {

  	struct __ip6_tnl_parm *p = &t->parms;

  	int ret = 0;

  	struct net *net = dev_net(t->dev);

  	if ((p->flags & IP6_TNL_F_CAP_RCV) ||
  	    ((p->flags & IP6_TNL_F_CAP_PER_PACKET) &&
  	     (ip6_tnl_get_cap(t, laddr, raddr) & IP6_TNL_F_CAP_RCV))) {

  		struct net_device *ldev = NULL;

  
  		if (p->link)

  			ldev = dev_get_by_index_rcu(net, p->link);

  		if ((ipv6_addr_is_multicast(laddr) ||
  		     likely(ipv6_chk_addr(net, laddr, ldev, 0))) &&
  		    likely(!ipv6_chk_addr(net, raddr, NULL, 0)))

  			ret = 1;

  	}
  	return ret;
  }

  EXPORT_SYMBOL_GPL(ip6_tnl_rcv_ctl);

  
  /**

   * ip6_tnl_rcv - decapsulate IPv6 packet and retransmit it locally

   *   @skb: received socket buffer

   *   @protocol: ethernet protocol ID
   *   @dscp_ecn_decapsulate: the function to decapsulate DSCP code and ECN

   *
   * Return: 0
   **/

  static int ip6_tnl_rcv(struct sk_buff *skb, __u16 protocol,

  		       __u8 ipproto,

  		       int (*dscp_ecn_decapsulate)(const struct ip6_tnl *t,
  						   const struct ipv6hdr *ipv6h,
  						   struct sk_buff *skb))

  {

  	struct ip6_tnl *t;

  	const struct ipv6hdr *ipv6h = ipv6_hdr(skb);

  	int err;

  	rcu_read_lock();

  	if ((t = ip6_tnl_lookup(dev_net(skb->dev), &ipv6h->saddr,

  					&ipv6h->daddr)) != NULL) {

  		struct pcpu_tstats *tstats;

  		if (t->parms.proto != ipproto && t->parms.proto != 0) {

  			rcu_read_unlock();

  			goto discard;
  		}

  		if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {

  			rcu_read_unlock();

  			goto discard;

  		}

  		if (!ip6_tnl_rcv_ctl(t, &ipv6h->daddr, &ipv6h->saddr)) {

  			t->dev->stats.rx_dropped++;

  			rcu_read_unlock();

  			goto discard;
  		}
  		secpath_reset(skb);

  		skb->mac_header = skb->network_header;

  		skb_reset_network_header(skb);

  		skb->protocol = htons(protocol);

  		skb->pkt_type = PACKET_HOST;
  		memset(skb->cb, 0, sizeof(struct inet6_skb_parm));

  		__skb_tunnel_rx(skb, t->dev);
  
  		err = dscp_ecn_decapsulate(t, ipv6h, skb);
  		if (unlikely(err)) {
  			if (log_ecn_error)
  				net_info_ratelimited("non-ECT from %pI6 with dsfield=%#x
  ",
  						     &ipv6h->saddr,
  						     ipv6_get_dsfield(ipv6h));
  			if (err > 1) {
  				++t->dev->stats.rx_frame_errors;
  				++t->dev->stats.rx_errors;
  				rcu_read_unlock();
  				goto discard;
  			}
  		}

  		tstats = this_cpu_ptr(t->dev->tstats);
  		tstats->rx_packets++;
  		tstats->rx_bytes += skb->len;

  		netif_rx(skb);

  		rcu_read_unlock();

  		return 0;
  	}

  	rcu_read_unlock();

  	return 1;

  
  discard:
  	kfree_skb(skb);
  	return 0;

  }

  static int ip4ip6_rcv(struct sk_buff *skb)
  {

  	return ip6_tnl_rcv(skb, ETH_P_IP, IPPROTO_IPIP,
  			   ip4ip6_dscp_ecn_decapsulate);

  }

  static int ip6ip6_rcv(struct sk_buff *skb)
  {

  	return ip6_tnl_rcv(skb, ETH_P_IPV6, IPPROTO_IPV6,
  			   ip6ip6_dscp_ecn_decapsulate);

  }

  struct ipv6_tel_txoption {
  	struct ipv6_txoptions ops;
  	__u8 dst_opt[8];
  };

  static void init_tel_txopt(struct ipv6_tel_txoption *opt, __u8 encap_limit)
  {
  	memset(opt, 0, sizeof(struct ipv6_tel_txoption));

  	opt->dst_opt[2] = IPV6_TLV_TNL_ENCAP_LIMIT;
  	opt->dst_opt[3] = 1;
  	opt->dst_opt[4] = encap_limit;
  	opt->dst_opt[5] = IPV6_TLV_PADN;
  	opt->dst_opt[6] = 1;

  	opt->ops.dst0opt = (struct ipv6_opt_hdr *) opt->dst_opt;
  	opt->ops.opt_nflen = 8;

  }
  
  /**

   * ip6_tnl_addr_conflict - compare packet addresses to tunnel's own

   *   @t: the outgoing tunnel device

   *   @hdr: IPv6 header from the incoming packet

   *
   * Description:

   *   Avoid trivial tunneling loop by checking that tunnel exit-point

   *   doesn't match source of incoming packet.
   *

   * Return:

   *   1 if conflict,
   *   0 else
   **/

  static inline bool

  ip6_tnl_addr_conflict(const struct ip6_tnl *t, const struct ipv6hdr *hdr)

  {
  	return ipv6_addr_equal(&t->parms.raddr, &hdr->saddr);
  }

  int ip6_tnl_xmit_ctl(struct ip6_tnl *t)

  {

  	struct __ip6_tnl_parm *p = &t->parms;

  	int ret = 0;

  	struct net *net = dev_net(t->dev);

  	if (p->flags & IP6_TNL_F_CAP_XMIT) {

  		struct net_device *ldev = NULL;

  		rcu_read_lock();

  		if (p->link)

  			ldev = dev_get_by_index_rcu(net, p->link);

  		if (unlikely(!ipv6_chk_addr(net, &p->laddr, ldev, 0)))

  			pr_warn("%s xmit: Local address not yet configured!
  ",
  				p->name);

  		else if (!ipv6_addr_is_multicast(&p->raddr) &&

  			 unlikely(ipv6_chk_addr(net, &p->raddr, NULL, 0)))

  			pr_warn("%s xmit: Routing loop! Remote address found on this node!
  ",
  				p->name);

  		else
  			ret = 1;

  		rcu_read_unlock();

  	}
  	return ret;
  }

  EXPORT_SYMBOL_GPL(ip6_tnl_xmit_ctl);

  /**

   * ip6_tnl_xmit2 - encapsulate packet and send

   *   @skb: the outgoing socket buffer

   *   @dev: the outgoing tunnel device

   *   @dsfield: dscp code for outer header
   *   @fl: flow of tunneled packet
   *   @encap_limit: encapsulation limit
   *   @pmtu: Path MTU is stored if packet is too big

   *
   * Description:
   *   Build new header and do some sanity checks on the packet before sending
   *   it.
   *

   * Return:

   *   0 on success

   *   -1 fail
   *   %-EMSGSIZE message too big. return mtu in this case.

   **/

  static int ip6_tnl_xmit2(struct sk_buff *skb,
  			 struct net_device *dev,
  			 __u8 dsfield,

  			 struct flowi6 *fl6,

  			 int encap_limit,
  			 __u32 *pmtu)

  {

  	struct net *net = dev_net(dev);

  	struct ip6_tnl *t = netdev_priv(dev);

  	struct net_device_stats *stats = &t->dev->stats;

  	struct ipv6hdr *ipv6h = ipv6_hdr(skb);

  	struct ipv6_tel_txoption opt;

  	struct dst_entry *dst = NULL, *ndst = NULL;

  	struct net_device *tdev;
  	int mtu;

  	unsigned int max_headroom = sizeof(struct ipv6hdr);

  	u8 proto;

  	int err = -1;

  	if (!fl6->flowi6_mark)
  		dst = ip6_tnl_dst_check(t);

  	if (!dst) {
  		ndst = ip6_route_output(net, NULL, fl6);

  		if (ndst->error)

  			goto tx_err_link_failure;

  		ndst = xfrm_lookup(net, ndst, flowi6_to_flowi(fl6), NULL, 0);
  		if (IS_ERR(ndst)) {
  			err = PTR_ERR(ndst);
  			ndst = NULL;

  			goto tx_err_link_failure;
  		}

  		dst = ndst;

  	}

  
  	tdev = dst->dev;
  
  	if (tdev == dev) {
  		stats->collisions++;

  		net_warn_ratelimited("%s: Local routing loop detected!
  ",
  				     t->parms.name);

  		goto tx_err_dst_release;
  	}
  	mtu = dst_mtu(dst) - sizeof (*ipv6h);

  	if (encap_limit >= 0) {

  		max_headroom += 8;
  		mtu -= 8;
  	}
  	if (mtu < IPV6_MIN_MTU)
  		mtu = IPV6_MIN_MTU;

  	if (skb_dst(skb))

  		skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);

  	if (skb->len > mtu) {

  		*pmtu = mtu;
  		err = -EMSGSIZE;

  		goto tx_err_dst_release;
  	}
  
  	/*
  	 * Okay, now see if we can stuff it in the buffer as-is.
  	 */
  	max_headroom += LL_RESERVED_SPACE(tdev);

  	if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
  	    (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {

  		struct sk_buff *new_skb;

  		if (!(new_skb = skb_realloc_headroom(skb, max_headroom)))
  			goto tx_err_dst_release;
  
  		if (skb->sk)
  			skb_set_owner_w(new_skb, skb->sk);

  		consume_skb(skb);

  		skb = new_skb;
  	}

  	skb_dst_drop(skb);

  	if (fl6->flowi6_mark) {
  		skb_dst_set(skb, dst);
  		ndst = NULL;
  	} else {
  		skb_dst_set_noref(skb, dst);
  	}

  	skb->transport_header = skb->network_header;

  	proto = fl6->flowi6_proto;

  	if (encap_limit >= 0) {
  		init_tel_txopt(&opt, encap_limit);
  		ipv6_push_nfrag_opts(skb, &opt.ops, &proto, NULL);
  	}

  	skb_push(skb, sizeof(struct ipv6hdr));
  	skb_reset_network_header(skb);

  	ipv6h = ipv6_hdr(skb);

  	ip6_flow_hdr(ipv6h, INET_ECN_encapsulate(0, dsfield), fl6->flowlabel);

  	ipv6h->hop_limit = t->parms.hop_limit;
  	ipv6h->nexthdr = proto;

  	ipv6h->saddr = fl6->saddr;
  	ipv6h->daddr = fl6->daddr;

  	ip6tunnel_xmit(skb, dev);

  	if (ndst)
  		ip6_tnl_dst_store(t, ndst);

  	return 0;
  tx_err_link_failure:
  	stats->tx_carrier_errors++;
  	dst_link_failure(skb);
  tx_err_dst_release:

  	dst_release(ndst);

  	return err;
  }
  
  static inline int

  ip4ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
  {
  	struct ip6_tnl *t = netdev_priv(dev);

  	const struct iphdr  *iph = ip_hdr(skb);

  	int encap_limit = -1;

  	struct flowi6 fl6;

  	__u8 dsfield;
  	__u32 mtu;
  	int err;

  	if ((t->parms.proto != IPPROTO_IPIP && t->parms.proto != 0) ||
  	    !ip6_tnl_xmit_ctl(t))

  		return -1;
  
  	if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
  		encap_limit = t->parms.encap_limit;

  	memcpy(&fl6, &t->fl.u.ip6, sizeof (fl6));
  	fl6.flowi6_proto = IPPROTO_IPIP;

  
  	dsfield = ipv4_get_dsfield(iph);

  	if (t->parms.flags & IP6_TNL_F_USE_ORIG_TCLASS)

  		fl6.flowlabel |= htonl((__u32)iph->tos << IPV6_TCLASS_SHIFT)

  					  & IPV6_TCLASS_MASK;

  	if (t->parms.flags & IP6_TNL_F_USE_ORIG_FWMARK)
  		fl6.flowi6_mark = skb->mark;

  	err = ip6_tnl_xmit2(skb, dev, dsfield, &fl6, encap_limit, &mtu);

  	if (err != 0) {
  		/* XXX: send ICMP error even if DF is not set. */
  		if (err == -EMSGSIZE)
  			icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
  				  htonl(mtu));
  		return -1;
  	}
  
  	return 0;
  }
  
  static inline int

  ip6ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
  {
  	struct ip6_tnl *t = netdev_priv(dev);

  	struct ipv6hdr *ipv6h = ipv6_hdr(skb);

  	int encap_limit = -1;
  	__u16 offset;

  	struct flowi6 fl6;

  	__u8 dsfield;
  	__u32 mtu;
  	int err;

  	if ((t->parms.proto != IPPROTO_IPV6 && t->parms.proto != 0) ||
  	    !ip6_tnl_xmit_ctl(t) || ip6_tnl_addr_conflict(t, ipv6h))

  		return -1;

  	offset = ip6_tnl_parse_tlv_enc_lim(skb, skb_network_header(skb));

  	if (offset > 0) {

  		struct ipv6_tlv_tnl_enc_lim *tel;

  		tel = (struct ipv6_tlv_tnl_enc_lim *)&skb_network_header(skb)[offset];

  		if (tel->encap_limit == 0) {
  			icmpv6_send(skb, ICMPV6_PARAMPROB,

  				    ICMPV6_HDR_FIELD, offset + 2);

  			return -1;
  		}
  		encap_limit = tel->encap_limit - 1;
  	} else if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
  		encap_limit = t->parms.encap_limit;

  	memcpy(&fl6, &t->fl.u.ip6, sizeof (fl6));
  	fl6.flowi6_proto = IPPROTO_IPV6;

  
  	dsfield = ipv6_get_dsfield(ipv6h);

  	if (t->parms.flags & IP6_TNL_F_USE_ORIG_TCLASS)

  		fl6.flowlabel |= (*(__be32 *) ipv6h & IPV6_TCLASS_MASK);

  	if (t->parms.flags & IP6_TNL_F_USE_ORIG_FLOWLABEL)

  		fl6.flowlabel |= (*(__be32 *) ipv6h & IPV6_FLOWLABEL_MASK);

  	if (t->parms.flags & IP6_TNL_F_USE_ORIG_FWMARK)
  		fl6.flowi6_mark = skb->mark;

  	err = ip6_tnl_xmit2(skb, dev, dsfield, &fl6, encap_limit, &mtu);

  	if (err != 0) {
  		if (err == -EMSGSIZE)

  			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);

  		return -1;
  	}
  
  	return 0;
  }

  static netdev_tx_t

  ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
  {
  	struct ip6_tnl *t = netdev_priv(dev);

  	struct net_device_stats *stats = &t->dev->stats;

  	int ret;

  	switch (skb->protocol) {

  	case htons(ETH_P_IP):

  		ret = ip4ip6_tnl_xmit(skb, dev);
  		break;

  	case htons(ETH_P_IPV6):

  		ret = ip6ip6_tnl_xmit(skb, dev);
  		break;
  	default:
  		goto tx_err;
  	}
  
  	if (ret < 0)
  		goto tx_err;

  	return NETDEV_TX_OK;

  tx_err:
  	stats->tx_errors++;
  	stats->tx_dropped++;
  	kfree_skb(skb);

  	return NETDEV_TX_OK;

  }

  static void ip6_tnl_link_config(struct ip6_tnl *t)

  {
  	struct net_device *dev = t->dev;

  	struct __ip6_tnl_parm *p = &t->parms;

  	struct flowi6 *fl6 = &t->fl.u.ip6;

  	memcpy(dev->dev_addr, &p->laddr, sizeof(struct in6_addr));
  	memcpy(dev->broadcast, &p->raddr, sizeof(struct in6_addr));

  
  	/* Set up flowi template */

  	fl6->saddr = p->laddr;
  	fl6->daddr = p->raddr;

  	fl6->flowi6_oif = p->link;
  	fl6->flowlabel = 0;

  
  	if (!(p->flags&IP6_TNL_F_USE_ORIG_TCLASS))

  		fl6->flowlabel |= IPV6_TCLASS_MASK & p->flowinfo;

  	if (!(p->flags&IP6_TNL_F_USE_ORIG_FLOWLABEL))

  		fl6->flowlabel |= IPV6_FLOWLABEL_MASK & p->flowinfo;

  	p->flags &= ~(IP6_TNL_F_CAP_XMIT|IP6_TNL_F_CAP_RCV|IP6_TNL_F_CAP_PER_PACKET);
  	p->flags |= ip6_tnl_get_cap(t, &p->laddr, &p->raddr);

  
  	if (p->flags&IP6_TNL_F_CAP_XMIT && p->flags&IP6_TNL_F_CAP_RCV)
  		dev->flags |= IFF_POINTOPOINT;
  	else
  		dev->flags &= ~IFF_POINTOPOINT;
  
  	dev->iflink = p->link;
  
  	if (p->flags & IP6_TNL_F_CAP_XMIT) {

  		int strict = (ipv6_addr_type(&p->raddr) &
  			      (IPV6_ADDR_MULTICAST|IPV6_ADDR_LINKLOCAL));

  		struct rt6_info *rt = rt6_lookup(dev_net(dev),
  						 &p->raddr, &p->laddr,

  						 p->link, strict);

  
  		if (rt == NULL)
  			return;

  		if (rt->dst.dev) {
  			dev->hard_header_len = rt->dst.dev->hard_header_len +

  				sizeof (struct ipv6hdr);

  			dev->mtu = rt->dst.dev->mtu - sizeof (struct ipv6hdr);

  			if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
  				dev->mtu-=8;

  
  			if (dev->mtu < IPV6_MIN_MTU)
  				dev->mtu = IPV6_MIN_MTU;
  		}

  		ip6_rt_put(rt);

  	}
  }
  
  /**

   * ip6_tnl_change - update the tunnel parameters

   *   @t: tunnel to be changed
   *   @p: tunnel configuration parameters

   *
   * Description:

   *   ip6_tnl_change() updates the tunnel parameters

   **/
  
  static int

  ip6_tnl_change(struct ip6_tnl *t, const struct __ip6_tnl_parm *p)

  {

  	t->parms.laddr = p->laddr;
  	t->parms.raddr = p->raddr;

  	t->parms.flags = p->flags;
  	t->parms.hop_limit = p->hop_limit;
  	t->parms.encap_limit = p->encap_limit;
  	t->parms.flowinfo = p->flowinfo;

  	t->parms.link = p->link;

  	t->parms.proto = p->proto;

  	ip6_tnl_dst_reset(t);

  	ip6_tnl_link_config(t);

  	return 0;
  }

  static int ip6_tnl_update(struct ip6_tnl *t, struct __ip6_tnl_parm *p)
  {
  	struct net *net = dev_net(t->dev);
  	struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);
  	int err;
  
  	ip6_tnl_unlink(ip6n, t);
  	synchronize_net();
  	err = ip6_tnl_change(t, p);
  	ip6_tnl_link(ip6n, t);
  	netdev_state_change(t->dev);
  	return err;
  }

  static void
  ip6_tnl_parm_from_user(struct __ip6_tnl_parm *p, const struct ip6_tnl_parm *u)
  {
  	p->laddr = u->laddr;
  	p->raddr = u->raddr;
  	p->flags = u->flags;
  	p->hop_limit = u->hop_limit;
  	p->encap_limit = u->encap_limit;
  	p->flowinfo = u->flowinfo;
  	p->link = u->link;
  	p->proto = u->proto;
  	memcpy(p->name, u->name, sizeof(u->name));
  }
  
  static void
  ip6_tnl_parm_to_user(struct ip6_tnl_parm *u, const struct __ip6_tnl_parm *p)
  {
  	u->laddr = p->laddr;
  	u->raddr = p->raddr;
  	u->flags = p->flags;
  	u->hop_limit = p->hop_limit;
  	u->encap_limit = p->encap_limit;
  	u->flowinfo = p->flowinfo;
  	u->link = p->link;
  	u->proto = p->proto;
  	memcpy(u->name, p->name, sizeof(u->name));
  }

  /**

   * ip6_tnl_ioctl - configure ipv6 tunnels from userspace

   *   @dev: virtual device associated with tunnel
   *   @ifr: parameters passed from userspace
   *   @cmd: command to be performed
   *
   * Description:

   *   ip6_tnl_ioctl() is used for managing IPv6 tunnels

   *   from userspace.

   *
   *   The possible commands are the following:
   *     %SIOCGETTUNNEL: get tunnel parameters for device
   *     %SIOCADDTUNNEL: add tunnel matching given tunnel parameters
   *     %SIOCCHGTUNNEL: change tunnel parameters to those given
   *     %SIOCDELTUNNEL: delete tunnel
   *

   *   The fallback device "ip6tnl0", created during module

   *   initialization, can be used for creating other tunnel devices.
   *
   * Return:
   *   0 on success,
   *   %-EFAULT if unable to copy data to or from userspace,
   *   %-EPERM if current process hasn't %CAP_NET_ADMIN set
   *   %-EINVAL if passed tunnel parameters are invalid,
   *   %-EEXIST if changing a tunnel's parameters would cause a conflict
   *   %-ENODEV if attempting to change or delete a nonexisting device
   **/
  
  static int

  ip6_tnl_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)

  {
  	int err = 0;

  	struct ip6_tnl_parm p;

  	struct __ip6_tnl_parm p1;

  	struct ip6_tnl *t = NULL;

  	struct net *net = dev_net(dev);
  	struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);

  
  	switch (cmd) {
  	case SIOCGETTUNNEL:

  		if (dev == ip6n->fb_tnl_dev) {

  			if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof (p))) {

  				err = -EFAULT;
  				break;
  			}

  			ip6_tnl_parm_from_user(&p1, &p);
  			t = ip6_tnl_locate(net, &p1, 0);

  		} else {
  			memset(&p, 0, sizeof(p));

  		}
  		if (t == NULL)

  			t = netdev_priv(dev);

  		ip6_tnl_parm_to_user(&p, &t->parms);

  		if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof (p))) {
  			err = -EFAULT;
  		}
  		break;
  	case SIOCADDTUNNEL:
  	case SIOCCHGTUNNEL:
  		err = -EPERM;

  		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))

  			break;

  		err = -EFAULT;
  		if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof (p)))

  			break;

  		err = -EINVAL;

  		if (p.proto != IPPROTO_IPV6 && p.proto != IPPROTO_IPIP &&
  		    p.proto != 0)

  			break;

  		ip6_tnl_parm_from_user(&p1, &p);
  		t = ip6_tnl_locate(net, &p1, cmd == SIOCADDTUNNEL);

  		if (dev != ip6n->fb_tnl_dev && cmd == SIOCCHGTUNNEL) {

  			if (t != NULL) {
  				if (t->dev != dev) {
  					err = -EEXIST;
  					break;
  				}
  			} else
  				t = netdev_priv(dev);

  			err = ip6_tnl_update(t, &p1);

  		}

  		if (t) {

  			err = 0;

  			ip6_tnl_parm_to_user(&p, &t->parms);
  			if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))

  				err = -EFAULT;
  
  		} else
  			err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);

  		break;
  	case SIOCDELTUNNEL:
  		err = -EPERM;

  		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))

  			break;

  		if (dev == ip6n->fb_tnl_dev) {

  			err = -EFAULT;
  			if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof (p)))

  				break;

  			err = -ENOENT;

  			ip6_tnl_parm_from_user(&p1, &p);
  			t = ip6_tnl_locate(net, &p1, 0);
  			if (t == NULL)

  				break;

  			err = -EPERM;

  			if (t->dev == ip6n->fb_tnl_dev)

  				break;

  			dev = t->dev;

  		}

  		err = 0;
  		unregister_netdevice(dev);

  		break;
  	default:
  		err = -EINVAL;
  	}
  	return err;
  }
  
  /**

   * ip6_tnl_change_mtu - change mtu manually for tunnel device

   *   @dev: virtual device associated with tunnel
   *   @new_mtu: the new mtu
   *
   * Return:
   *   0 on success,
   *   %-EINVAL if mtu too small
   **/
  
  static int