/*
   *	GRE over IPv6 protocol decoder.
   *
   *	Authors: Dmitry Kozlov (xeb@mail.ru)
   *
   *	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/capability.h>
  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/uaccess.h>
  #include <linux/skbuff.h>
  #include <linux/netdevice.h>
  #include <linux/in.h>
  #include <linux/tcp.h>
  #include <linux/udp.h>
  #include <linux/if_arp.h>

  #include <linux/init.h>
  #include <linux/in6.h>
  #include <linux/inetdevice.h>
  #include <linux/igmp.h>
  #include <linux/netfilter_ipv4.h>
  #include <linux/etherdevice.h>
  #include <linux/if_ether.h>
  #include <linux/hash.h>
  #include <linux/if_tunnel.h>
  #include <linux/ip6_tunnel.h>
  
  #include <net/sock.h>
  #include <net/ip.h>

  #include <net/ip_tunnels.h>

  #include <net/icmp.h>
  #include <net/protocol.h>
  #include <net/addrconf.h>
  #include <net/arp.h>
  #include <net/checksum.h>
  #include <net/dsfield.h>
  #include <net/inet_ecn.h>
  #include <net/xfrm.h>
  #include <net/net_namespace.h>
  #include <net/netns/generic.h>
  #include <net/rtnetlink.h>
  
  #include <net/ipv6.h>
  #include <net/ip6_fib.h>
  #include <net/ip6_route.h>
  #include <net/ip6_tunnel.h>

  #include <net/gre.h>

  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");

  #define IP6_GRE_HASH_SIZE_SHIFT  5
  #define IP6_GRE_HASH_SIZE (1 << IP6_GRE_HASH_SIZE_SHIFT)

  
  static int ip6gre_net_id __read_mostly;
  struct ip6gre_net {

  	struct ip6_tnl __rcu *tunnels[4][IP6_GRE_HASH_SIZE];

  
  	struct net_device *fb_tunnel_dev;
  };
  
  static struct rtnl_link_ops ip6gre_link_ops __read_mostly;

  static struct rtnl_link_ops ip6gre_tap_ops __read_mostly;

  static int ip6gre_tunnel_init(struct net_device *dev);
  static void ip6gre_tunnel_setup(struct net_device *dev);
  static void ip6gre_tunnel_link(struct ip6gre_net *ign, struct ip6_tnl *t);
  static void ip6gre_tnl_link_config(struct ip6_tnl *t, int set_mtu);
  
  /* Tunnel hash table */
  
  /*
     4 hash tables:
  
     3: (remote,local)
     2: (remote,*)
     1: (*,local)
     0: (*,*)
  
     We require exact key match i.e. if a key is present in packet
     it will match only tunnel with the same key; if it is not present,
     it will match only keyless tunnel.
  
     All keysless packets, if not matched configured keyless tunnels
     will match fallback tunnel.
   */

  #define HASH_KEY(key) (((__force u32)key^((__force u32)key>>4))&(IP6_GRE_HASH_SIZE - 1))

  static u32 HASH_ADDR(const struct in6_addr *addr)
  {
  	u32 hash = ipv6_addr_hash(addr);

  	return hash_32(hash, IP6_GRE_HASH_SIZE_SHIFT);

  }
  
  #define tunnels_r_l	tunnels[3]
  #define tunnels_r	tunnels[2]
  #define tunnels_l	tunnels[1]
  #define tunnels_wc	tunnels[0]

  /* Given src, dst and key, find appropriate for input tunnel. */
  
  static struct ip6_tnl *ip6gre_tunnel_lookup(struct net_device *dev,
  		const struct in6_addr *remote, const struct in6_addr *local,
  		__be32 key, __be16 gre_proto)
  {
  	struct net *net = dev_net(dev);
  	int link = dev->ifindex;
  	unsigned int h0 = HASH_ADDR(remote);
  	unsigned int h1 = HASH_KEY(key);
  	struct ip6_tnl *t, *cand = NULL;
  	struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
  	int dev_type = (gre_proto == htons(ETH_P_TEB)) ?
  		       ARPHRD_ETHER : ARPHRD_IP6GRE;
  	int score, cand_score = 4;

  	for_each_ip_tunnel_rcu(t, ign->tunnels_r_l[h0 ^ h1]) {

  		if (!ipv6_addr_equal(local, &t->parms.laddr) ||
  		    !ipv6_addr_equal(remote, &t->parms.raddr) ||
  		    key != t->parms.i_key ||
  		    !(t->dev->flags & IFF_UP))
  			continue;
  
  		if (t->dev->type != ARPHRD_IP6GRE &&
  		    t->dev->type != dev_type)
  			continue;
  
  		score = 0;
  		if (t->parms.link != link)
  			score |= 1;
  		if (t->dev->type != dev_type)
  			score |= 2;
  		if (score == 0)
  			return t;
  
  		if (score < cand_score) {
  			cand = t;
  			cand_score = score;
  		}
  	}

  	for_each_ip_tunnel_rcu(t, ign->tunnels_r[h0 ^ h1]) {

  		if (!ipv6_addr_equal(remote, &t->parms.raddr) ||
  		    key != t->parms.i_key ||
  		    !(t->dev->flags & IFF_UP))
  			continue;
  
  		if (t->dev->type != ARPHRD_IP6GRE &&
  		    t->dev->type != dev_type)
  			continue;
  
  		score = 0;
  		if (t->parms.link != link)
  			score |= 1;
  		if (t->dev->type != dev_type)
  			score |= 2;
  		if (score == 0)
  			return t;
  
  		if (score < cand_score) {
  			cand = t;
  			cand_score = score;
  		}
  	}

  	for_each_ip_tunnel_rcu(t, ign->tunnels_l[h1]) {

  		if ((!ipv6_addr_equal(local, &t->parms.laddr) &&
  			  (!ipv6_addr_equal(local, &t->parms.raddr) ||
  				 !ipv6_addr_is_multicast(local))) ||
  		    key != t->parms.i_key ||
  		    !(t->dev->flags & IFF_UP))
  			continue;
  
  		if (t->dev->type != ARPHRD_IP6GRE &&
  		    t->dev->type != dev_type)
  			continue;
  
  		score = 0;
  		if (t->parms.link != link)
  			score |= 1;
  		if (t->dev->type != dev_type)
  			score |= 2;
  		if (score == 0)
  			return t;
  
  		if (score < cand_score) {
  			cand = t;
  			cand_score = score;
  		}
  	}

  	for_each_ip_tunnel_rcu(t, ign->tunnels_wc[h1]) {

  		if (t->parms.i_key != key ||
  		    !(t->dev->flags & IFF_UP))
  			continue;
  
  		if (t->dev->type != ARPHRD_IP6GRE &&
  		    t->dev->type != dev_type)
  			continue;
  
  		score = 0;
  		if (t->parms.link != link)
  			score |= 1;
  		if (t->dev->type != dev_type)
  			score |= 2;
  		if (score == 0)
  			return t;
  
  		if (score < cand_score) {
  			cand = t;
  			cand_score = score;
  		}
  	}

  	if (cand)

  		return cand;
  
  	dev = ign->fb_tunnel_dev;
  	if (dev->flags & IFF_UP)
  		return netdev_priv(dev);
  
  	return NULL;
  }
  
  static struct ip6_tnl __rcu **__ip6gre_bucket(struct ip6gre_net *ign,
  		const struct __ip6_tnl_parm *p)
  {
  	const struct in6_addr *remote = &p->raddr;
  	const struct in6_addr *local = &p->laddr;
  	unsigned int h = HASH_KEY(p->i_key);
  	int prio = 0;
  
  	if (!ipv6_addr_any(local))
  		prio |= 1;
  	if (!ipv6_addr_any(remote) && !ipv6_addr_is_multicast(remote)) {
  		prio |= 2;
  		h ^= HASH_ADDR(remote);
  	}
  
  	return &ign->tunnels[prio][h];
  }
  
  static inline struct ip6_tnl __rcu **ip6gre_bucket(struct ip6gre_net *ign,
  		const struct ip6_tnl *t)
  {
  	return __ip6gre_bucket(ign, &t->parms);
  }
  
  static void ip6gre_tunnel_link(struct ip6gre_net *ign, struct ip6_tnl *t)
  {
  	struct ip6_tnl __rcu **tp = ip6gre_bucket(ign, t);
  
  	rcu_assign_pointer(t->next, rtnl_dereference(*tp));
  	rcu_assign_pointer(*tp, t);
  }
  
  static void ip6gre_tunnel_unlink(struct ip6gre_net *ign, struct ip6_tnl *t)
  {
  	struct ip6_tnl __rcu **tp;
  	struct ip6_tnl *iter;
  
  	for (tp = ip6gre_bucket(ign, t);
  	     (iter = rtnl_dereference(*tp)) != NULL;
  	     tp = &iter->next) {
  		if (t == iter) {
  			rcu_assign_pointer(*tp, t->next);
  			break;
  		}
  	}
  }
  
  static struct ip6_tnl *ip6gre_tunnel_find(struct net *net,
  					   const struct __ip6_tnl_parm *parms,
  					   int type)
  {
  	const struct in6_addr *remote = &parms->raddr;
  	const struct in6_addr *local = &parms->laddr;
  	__be32 key = parms->i_key;
  	int link = parms->link;
  	struct ip6_tnl *t;
  	struct ip6_tnl __rcu **tp;
  	struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
  
  	for (tp = __ip6gre_bucket(ign, parms);
  	     (t = rtnl_dereference(*tp)) != NULL;
  	     tp = &t->next)
  		if (ipv6_addr_equal(local, &t->parms.laddr) &&
  		    ipv6_addr_equal(remote, &t->parms.raddr) &&
  		    key == t->parms.i_key &&
  		    link == t->parms.link &&
  		    type == t->dev->type)
  			break;
  
  	return t;
  }
  
  static struct ip6_tnl *ip6gre_tunnel_locate(struct net *net,
  		const struct __ip6_tnl_parm *parms, int create)
  {
  	struct ip6_tnl *t, *nt;
  	struct net_device *dev;
  	char name[IFNAMSIZ];
  	struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
  
  	t = ip6gre_tunnel_find(net, parms, ARPHRD_IP6GRE);

  	if (t && create)
  		return NULL;

  	if (t || !create)
  		return t;
  
  	if (parms->name[0])
  		strlcpy(name, parms->name, IFNAMSIZ);
  	else
  		strcpy(name, "ip6gre%d");

  	dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN,
  			   ip6gre_tunnel_setup);

  	if (!dev)
  		return NULL;
  
  	dev_net_set(dev, net);
  
  	nt = netdev_priv(dev);
  	nt->parms = *parms;
  	dev->rtnl_link_ops = &ip6gre_link_ops;
  
  	nt->dev = dev;

  	nt->net = dev_net(dev);

  	ip6gre_tnl_link_config(nt, 1);
  
  	if (register_netdevice(dev) < 0)
  		goto failed_free;
  
  	/* Can use a lockless transmit, unless we generate output sequences */

  	if (!(nt->parms.o_flags & TUNNEL_SEQ))

  		dev->features |= NETIF_F_LLTX;
  
  	dev_hold(dev);
  	ip6gre_tunnel_link(ign, nt);
  	return nt;
  
  failed_free:
  	free_netdev(dev);
  	return NULL;
  }
  
  static void ip6gre_tunnel_uninit(struct net_device *dev)
  {

  	struct ip6_tnl *t = netdev_priv(dev);
  	struct ip6gre_net *ign = net_generic(t->net, ip6gre_net_id);

  	ip6gre_tunnel_unlink(ign, t);

  	dst_cache_reset(&t->dst_cache);

  	dev_put(dev);
  }
  
  
  static void ip6gre_err(struct sk_buff *skb, struct inet6_skb_parm *opt,

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

  {

  	const struct gre_base_hdr *greh;
  	const struct ipv6hdr *ipv6h;
  	int grehlen = sizeof(*greh);

  	struct ip6_tnl *t;

  	int key_off = 0;

  	__be16 flags;

  	__be32 key;

  	if (!pskb_may_pull(skb, offset + grehlen))
  		return;
  	greh = (const struct gre_base_hdr *)(skb->data + offset);
  	flags = greh->flags;
  	if (flags & (GRE_VERSION | GRE_ROUTING))
  		return;
  	if (flags & GRE_CSUM)
  		grehlen += 4;
  	if (flags & GRE_KEY) {
  		key_off = grehlen + offset;
  		grehlen += 4;

  	}

  	if (!pskb_may_pull(skb, offset + grehlen))

  		return;

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

  	greh = (const struct gre_base_hdr *)(skb->data + offset);
  	key = key_off ? *(__be32 *)(skb->data + key_off) : 0;

  	t = ip6gre_tunnel_lookup(skb->dev, &ipv6h->daddr, &ipv6h->saddr,

  				 key, greh->protocol);

  	if (!t)

  		return;

  
  	switch (type) {
  		__u32 teli;
  		struct ipv6_tlv_tnl_enc_lim *tel;
  		__u32 mtu;
  	case ICMPV6_DEST_UNREACH:

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

  		break;
  	case ICMPV6_TIME_EXCEED:
  		if (code == ICMPV6_EXC_HOPLIMIT) {

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

  		}
  		break;
  	case ICMPV6_PARAMPROB:
  		teli = 0;
  		if (code == ICMPV6_HDR_FIELD)
  			teli = ip6_tnl_parse_tlv_enc_lim(skb, skb->data);

  		if (teli && teli == be32_to_cpu(info) - 2) {

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

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

  			}
  		} else {

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

  		}
  		break;
  	case ICMPV6_PKT_TOOBIG:

  		mtu = be32_to_cpu(info) - offset;

  		if (mtu < IPV6_MIN_MTU)
  			mtu = IPV6_MIN_MTU;
  		t->dev->mtu = mtu;
  		break;
  	}
  
  	if (time_before(jiffies, t->err_time + IP6TUNNEL_ERR_TIMEO))
  		t->err_count++;
  	else
  		t->err_count = 1;
  	t->err_time = jiffies;

  }

  static int ip6gre_rcv(struct sk_buff *skb, const struct tnl_ptk_info *tpi)

  {
  	const struct ipv6hdr *ipv6h;

  	struct ip6_tnl *tunnel;

  
  	ipv6h = ipv6_hdr(skb);

  	tunnel = ip6gre_tunnel_lookup(skb->dev,

  				      &ipv6h->saddr, &ipv6h->daddr, tpi->key,
  				      tpi->proto);

  	if (tunnel) {

  		ip6_tnl_rcv(tunnel, skb, tpi, NULL, false);

  		return PACKET_RCVD;
  	}

  	return PACKET_REJECT;
  }

  static int gre_rcv(struct sk_buff *skb)
  {
  	struct tnl_ptk_info tpi;
  	bool csum_err = false;
  	int hdr_len;

  	hdr_len = gre_parse_header(skb, &tpi, &csum_err, htons(ETH_P_IPV6), 0);

  	if (hdr_len < 0)

  		goto drop;

  	if (iptunnel_pull_header(skb, hdr_len, tpi.proto, false))
  		goto drop;

  	if (ip6gre_rcv(skb, &tpi) == PACKET_RCVD)

  		return 0;

  	icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);

  drop:

  	kfree_skb(skb);
  	return 0;
  }
  
  struct ipv6_tel_txoption {
  	struct ipv6_txoptions ops;
  	__u8 dst_opt[8];
  };

  static int gre_handle_offloads(struct sk_buff *skb, bool csum)

  {

  	return iptunnel_handle_offloads(skb,
  					csum ? SKB_GSO_GRE_CSUM : SKB_GSO_GRE);

  }

  static netdev_tx_t __gre6_xmit(struct sk_buff *skb,
  			       struct net_device *dev, __u8 dsfield,
  			       struct flowi6 *fl6, int encap_limit,
  			       __u32 *pmtu, __be16 proto)

  {

  	struct ip6_tnl *tunnel = netdev_priv(dev);

  	__be16 protocol = (dev->type == ARPHRD_ETHER) ?
  			  htons(ETH_P_TEB) : proto;

  
  	if (dev->type == ARPHRD_ETHER)
  		IPCB(skb)->flags = 0;

  	if (dev->header_ops && dev->type == ARPHRD_IP6GRE)
  		fl6->daddr = ((struct ipv6hdr *)skb->data)->daddr;
  	else

  		fl6->daddr = tunnel->parms.raddr;

  	if (tunnel->parms.o_flags & TUNNEL_SEQ)
  		tunnel->o_seqno++;

  	/* Push GRE header. */
  	gre_build_header(skb, tunnel->tun_hlen, tunnel->parms.o_flags,
  			 protocol, tunnel->parms.o_key, htonl(tunnel->o_seqno));

  	return ip6_tnl_xmit(skb, dev, dsfield, fl6, encap_limit, pmtu,
  			    NEXTHDR_GRE);

  }
  
  static inline int ip6gre_xmit_ipv4(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;

  	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));

  	if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
  		encap_limit = t->parms.encap_limit;
  
  	memcpy(&fl6, &t->fl.u.ip6, sizeof(fl6));

  
  	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 = gre_handle_offloads(skb, !!(t->parms.o_flags & TUNNEL_CSUM));
  	if (err)
  		return -1;
  
  	err = __gre6_xmit(skb, dev, dsfield, &fl6, encap_limit, &mtu,
  			  skb->protocol);

  	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 ip6gre_xmit_ipv6(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 (ipv6_addr_equal(&t->parms.raddr, &ipv6h->saddr))
  		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));

  
  	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 |= ip6_flowlabel(ipv6h);

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

  	if (gre_handle_offloads(skb, !!(t->parms.o_flags & TUNNEL_CSUM)))
  		return -1;
  
  	err = __gre6_xmit(skb, dev, dsfield, &fl6, encap_limit,
  			  &mtu, skb->protocol);

  	if (err != 0) {
  		if (err == -EMSGSIZE)
  			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
  		return -1;
  	}
  
  	return 0;
  }
  
  /**
   * 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 ip6gre_tnl_addr_conflict(const struct ip6_tnl *t,
  	const struct ipv6hdr *hdr)
  {
  	return ipv6_addr_equal(&t->parms.raddr, &hdr->saddr);
  }
  
  static int ip6gre_xmit_other(struct sk_buff *skb, struct net_device *dev)
  {
  	struct ip6_tnl *t = netdev_priv(dev);
  	int encap_limit = -1;
  	struct flowi6 fl6;
  	__u32 mtu;
  	int err;
  
  	if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
  		encap_limit = t->parms.encap_limit;
  
  	memcpy(&fl6, &t->fl.u.ip6, sizeof(fl6));

  	err = gre_handle_offloads(skb, !!(t->parms.o_flags & TUNNEL_CSUM));
  	if (err)
  		return err;
  
  	err = __gre6_xmit(skb, dev, 0, &fl6, encap_limit, &mtu, skb->protocol);

  
  	return err;
  }
  
  static netdev_tx_t ip6gre_tunnel_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;

  	if (!ip6_tnl_xmit_ctl(t, &t->parms.laddr, &t->parms.raddr))

  		goto tx_err;

  
  	switch (skb->protocol) {
  	case htons(ETH_P_IP):
  		ret = ip6gre_xmit_ipv4(skb, dev);
  		break;
  	case htons(ETH_P_IPV6):
  		ret = ip6gre_xmit_ipv6(skb, dev);
  		break;
  	default:
  		ret = ip6gre_xmit_other(skb, dev);
  		break;
  	}
  
  	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 ip6gre_tnl_link_config(struct ip6_tnl *t, int set_mtu)
  {
  	struct net_device *dev = t->dev;
  	struct __ip6_tnl_parm *p = &t->parms;
  	struct flowi6 *fl6 = &t->fl.u.ip6;

  	int t_hlen;

  
  	if (dev->type != ARPHRD_ETHER) {
  		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;

  	fl6->flowi6_proto = IPPROTO_GRE;

  
  	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->type != ARPHRD_ETHER)
  		dev->flags |= IFF_POINTOPOINT;
  	else
  		dev->flags &= ~IFF_POINTOPOINT;

  	t->tun_hlen = gre_calc_hlen(t->parms.o_flags);

  	t->hlen = t->encap_hlen + t->tun_hlen;

  
  	t_hlen = t->hlen + sizeof(struct ipv6hdr);

  
  	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(t->net,

  						 &p->raddr, &p->laddr,
  						 p->link, strict);

  		if (!rt)

  			return;
  
  		if (rt->dst.dev) {

  			dev->hard_header_len = rt->dst.dev->hard_header_len +
  					       t_hlen;

  
  			if (set_mtu) {

  				dev->mtu = rt->dst.dev->mtu - t_hlen;

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

  				if (dev->type == ARPHRD_ETHER)
  					dev->mtu -= ETH_HLEN;

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

  		ip6_rt_put(rt);

  	}

  }
  
  static int ip6gre_tnl_change(struct ip6_tnl *t,
  	const struct __ip6_tnl_parm *p, int set_mtu)
  {
  	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;
  	t->parms.i_key = p->i_key;
  	t->parms.o_key = p->o_key;
  	t->parms.i_flags = p->i_flags;
  	t->parms.o_flags = p->o_flags;

  	dst_cache_reset(&t->dst_cache);

  	ip6gre_tnl_link_config(t, set_mtu);
  	return 0;
  }
  
  static void ip6gre_tnl_parm_from_user(struct __ip6_tnl_parm *p,
  	const struct ip6_tnl_parm2 *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->i_key = u->i_key;
  	p->o_key = u->o_key;

  	p->i_flags = gre_flags_to_tnl_flags(u->i_flags);
  	p->o_flags = gre_flags_to_tnl_flags(u->o_flags);

  	memcpy(p->name, u->name, sizeof(u->name));
  }
  
  static void ip6gre_tnl_parm_to_user(struct ip6_tnl_parm2 *u,
  	const struct __ip6_tnl_parm *p)
  {
  	u->proto = IPPROTO_GRE;
  	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->i_key = p->i_key;
  	u->o_key = p->o_key;

  	u->i_flags = gre_tnl_flags_to_gre_flags(p->i_flags);
  	u->o_flags = gre_tnl_flags_to_gre_flags(p->o_flags);

  	memcpy(u->name, p->name, sizeof(u->name));
  }
  
  static int ip6gre_tunnel_ioctl(struct net_device *dev,
  	struct ifreq *ifr, int cmd)
  {
  	int err = 0;
  	struct ip6_tnl_parm2 p;
  	struct __ip6_tnl_parm p1;

  	struct ip6_tnl *t = netdev_priv(dev);
  	struct net *net = t->net;

  	struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);

  	memset(&p1, 0, sizeof(p1));

  	switch (cmd) {
  	case SIOCGETTUNNEL:

  		if (dev == ign->fb_tunnel_dev) {
  			if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
  				err = -EFAULT;
  				break;
  			}
  			ip6gre_tnl_parm_from_user(&p1, &p);
  			t = ip6gre_tunnel_locate(net, &p1, 0);

  			if (!t)

  				t = netdev_priv(dev);

  		}

  		memset(&p, 0, sizeof(p));

  		ip6gre_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))

  			goto done;
  
  		err = -EFAULT;
  		if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
  			goto done;
  
  		err = -EINVAL;
  		if ((p.i_flags|p.o_flags)&(GRE_VERSION|GRE_ROUTING))
  			goto done;
  
  		if (!(p.i_flags&GRE_KEY))
  			p.i_key = 0;
  		if (!(p.o_flags&GRE_KEY))
  			p.o_key = 0;
  
  		ip6gre_tnl_parm_from_user(&p1, &p);
  		t = ip6gre_tunnel_locate(net, &p1, cmd == SIOCADDTUNNEL);
  
  		if (dev != ign->fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {

  			if (t) {

  				if (t->dev != dev) {
  					err = -EEXIST;
  					break;
  				}
  			} else {
  				t = netdev_priv(dev);
  
  				ip6gre_tunnel_unlink(ign, t);
  				synchronize_net();
  				ip6gre_tnl_change(t, &p1, 1);
  				ip6gre_tunnel_link(ign, t);
  				netdev_state_change(dev);
  			}
  		}
  
  		if (t) {
  			err = 0;

  			memset(&p, 0, sizeof(p));

  			ip6gre_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))

  			goto done;
  
  		if (dev == ign->fb_tunnel_dev) {
  			err = -EFAULT;
  			if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
  				goto done;
  			err = -ENOENT;
  			ip6gre_tnl_parm_from_user(&p1, &p);
  			t = ip6gre_tunnel_locate(net, &p1, 0);

  			if (!t)

  				goto done;
  			err = -EPERM;
  			if (t == netdev_priv(ign->fb_tunnel_dev))
  				goto done;
  			dev = t->dev;
  		}
  		unregister_netdevice(dev);
  		err = 0;
  		break;
  
  	default:
  		err = -EINVAL;
  	}
  
  done:
  	return err;
  }

  static int ip6gre_header(struct sk_buff *skb, struct net_device *dev,
  			unsigned short type,
  			const void *daddr, const void *saddr, unsigned int len)
  {
  	struct ip6_tnl *t = netdev_priv(dev);
  	struct ipv6hdr *ipv6h = (struct ipv6hdr *)skb_push(skb, t->hlen);
  	__be16 *p = (__be16 *)(ipv6h+1);

  	ip6_flow_hdr(ipv6h, 0,
  		     ip6_make_flowlabel(dev_net(dev), skb,

  					t->fl.u.ip6.flowlabel, true,

  					&t->fl.u.ip6));

  	ipv6h->hop_limit = t->parms.hop_limit;
  	ipv6h->nexthdr = NEXTHDR_GRE;
  	ipv6h->saddr = t->parms.laddr;
  	ipv6h->daddr = t->parms.raddr;
  
  	p[0]		= t->parms.o_flags;
  	p[1]		= htons(type);
  
  	/*
  	 *	Set the source hardware address.
  	 */
  
  	if (saddr)
  		memcpy(&ipv6h->saddr, saddr, sizeof(struct in6_addr));
  	if (daddr)
  		memcpy(&ipv6h->daddr, daddr, sizeof(struct in6_addr));
  	if (!ipv6_addr_any(&ipv6h->daddr))
  		return t->hlen;
  
  	return -t->hlen;
  }

  static const struct header_ops ip6gre_header_ops = {
  	.create	= ip6gre_header,

  };
  
  static const struct net_device_ops ip6gre_netdev_ops = {
  	.ndo_init		= ip6gre_tunnel_init,
  	.ndo_uninit		= ip6gre_tunnel_uninit,
  	.ndo_start_xmit		= ip6gre_tunnel_xmit,
  	.ndo_do_ioctl		= ip6gre_tunnel_ioctl,

  	.ndo_change_mtu		= ip6_tnl_change_mtu,

  	.ndo_get_stats64	= ip_tunnel_get_stats64,

  	.ndo_get_iflink		= ip6_tnl_get_iflink,

  };
  
  static void ip6gre_dev_free(struct net_device *dev)
  {

  	struct ip6_tnl *t = netdev_priv(dev);

  	dst_cache_destroy(&t->dst_cache);

  	free_percpu(dev->tstats);
  	free_netdev(dev);
  }
  
  static void ip6gre_tunnel_setup(struct net_device *dev)
  {

  	dev->netdev_ops = &ip6gre_netdev_ops;
  	dev->destructor = ip6gre_dev_free;
  
  	dev->type = ARPHRD_IP6GRE;

  	dev->flags |= IFF_NOARP;

  	dev->addr_len = sizeof(struct in6_addr);

  	netif_keep_dst(dev);

  }

  static int ip6gre_tunnel_init_common(struct net_device *dev)

  {
  	struct ip6_tnl *tunnel;

  	int ret;

  	int t_hlen;

  
  	tunnel = netdev_priv(dev);
  
  	tunnel->dev = dev;

  	tunnel->net = dev_net(dev);

  	strcpy(tunnel->parms.name, dev->name);

  	dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
  	if (!dev->tstats)
  		return -ENOMEM;

  	ret = dst_cache_init(&tunnel->dst_cache, GFP_KERNEL);

  	if (ret) {
  		free_percpu(dev->tstats);
  		dev->tstats = NULL;
  		return ret;
  	}

  	tunnel->tun_hlen = gre_calc_hlen(tunnel->parms.o_flags);

  	tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen;

  	t_hlen = tunnel->hlen + sizeof(struct ipv6hdr);

  	dev->hard_header_len = LL_MAX_HEADER + t_hlen;
  	dev->mtu = ETH_DATA_LEN - t_hlen;

  	if (dev->type == ARPHRD_ETHER)
  		dev->mtu -= ETH_HLEN;

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

  	return 0;
  }
  
  static int ip6gre_tunnel_init(struct net_device *dev)
  {
  	struct ip6_tnl *tunnel;
  	int ret;
  
  	ret = ip6gre_tunnel_init_common(dev);
  	if (ret)
  		return ret;
  
  	tunnel = netdev_priv(dev);

  	memcpy(dev->dev_addr, &tunnel->parms.laddr, sizeof(struct in6_addr));
  	memcpy(dev->broadcast, &tunnel->parms.raddr, sizeof(struct in6_addr));
  
  	if (ipv6_addr_any(&tunnel->parms.raddr))
  		dev->header_ops = &ip6gre_header_ops;

  	return 0;
  }
  
  static void ip6gre_fb_tunnel_init(struct net_device *dev)
  {
  	struct ip6_tnl *tunnel = netdev_priv(dev);
  
  	tunnel->dev = dev;

  	tunnel->net = dev_net(dev);

  	strcpy(tunnel->parms.name, dev->name);
  
  	tunnel->hlen		= sizeof(struct ipv6hdr) + 4;
  
  	dev_hold(dev);
  }
  
  
  static struct inet6_protocol ip6gre_protocol __read_mostly = {

  	.handler     = gre_rcv,

  	.err_handler = ip6gre_err,
  	.flags       = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
  };

  static void ip6gre_destroy_tunnels(struct net *net, struct list_head *head)

  {

  	struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
  	struct net_device *dev, *aux;

  	int prio;

  	for_each_netdev_safe(net, dev, aux)
  		if (dev->rtnl_link_ops == &ip6gre_link_ops ||
  		    dev->rtnl_link_ops == &ip6gre_tap_ops)
  			unregister_netdevice_queue(dev, head);

  	for (prio = 0; prio < 4; prio++) {
  		int h;

  		for (h = 0; h < IP6_GRE_HASH_SIZE; h++) {

  			struct ip6_tnl *t;
  
  			t = rtnl_dereference(ign->tunnels[prio][h]);

  			while (t) {

  				/* If dev is in the same netns, it has already
  				 * been added to the list by the previous loop.
  				 */
  				if (!net_eq(dev_net(t->dev), net))
  					unregister_netdevice_queue(t->dev,
  								   head);

  				t = rtnl_dereference(t->next);
  			}
  		}
  	}
  }
  
  static int __net_init ip6gre_init_net(struct net *net)
  {
  	struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
  	int err;
  
  	ign->fb_tunnel_dev = alloc_netdev(sizeof(struct ip6_tnl), "ip6gre0",

  					  NET_NAME_UNKNOWN,
  					  ip6gre_tunnel_setup);

  	if (!ign->fb_tunnel_dev) {
  		err = -ENOMEM;
  		goto err_alloc_dev;
  	}
  	dev_net_set(ign->fb_tunnel_dev, net);

  	/* FB netdevice is special: we have one, and only one per netns.
  	 * Allowing to move it to another netns is clearly unsafe.
  	 */
  	ign->fb_tunnel_dev->features |= NETIF_F_NETNS_LOCAL;

  
  	ip6gre_fb_tunnel_init(ign->fb_tunnel_dev);
  	ign->fb_tunnel_dev->rtnl_link_ops = &ip6gre_link_ops;
  
  	err = register_netdev(ign->fb_tunnel_dev);
  	if (err)
  		goto err_reg_dev;
  
  	rcu_assign_pointer(ign->tunnels_wc[0],
  			   netdev_priv(ign->fb_tunnel_dev));
  	return 0;
  
  err_reg_dev:
  	ip6gre_dev_free(ign->fb_tunnel_dev);
  err_alloc_dev:
  	return err;
  }
  
  static void __net_exit ip6gre_exit_net(struct net *net)
  {

  	LIST_HEAD(list);

  	rtnl_lock();

  	ip6gre_destroy_tunnels(net, &list);

  	unregister_netdevice_many(&list);
  	rtnl_unlock();
  }
  
  static struct pernet_operations ip6gre_net_ops = {
  	.init = ip6gre_init_net,
  	.exit = ip6gre_exit_net,
  	.id   = &ip6gre_net_id,
  	.size = sizeof(struct ip6gre_net),
  };
  
  static int ip6gre_tunnel_validate(struct nlattr *tb[], struct nlattr *data[])
  {
  	__be16 flags;
  
  	if (!data)
  		return 0;
  
  	flags = 0;
  	if (data[IFLA_GRE_IFLAGS])
  		flags |= nla_get_be16(data[IFLA_GRE_IFLAGS]);
  	if (data[IFLA_GRE_OFLAGS])
  		flags |= nla_get_be16(data[IFLA_GRE_OFLAGS]);
  	if (flags & (GRE_VERSION|GRE_ROUTING))
  		return -EINVAL;
  
  	return 0;
  }
  
  static int ip6gre_tap_validate(struct nlattr *tb[], struct nlattr *data[])
  {
  	struct in6_addr daddr;
  
  	if (tb[IFLA_ADDRESS]) {
  		if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
  			return -EINVAL;
  		if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
  			return -EADDRNOTAVAIL;
  	}
  
  	if (!data)
  		goto out;
  
  	if (data[IFLA_GRE_REMOTE]) {

  		daddr = nla_get_in6_addr(data[IFLA_GRE_REMOTE]);

  		if (ipv6_addr_any(&daddr))
  			return -EINVAL;
  	}
  
  out:
  	return ip6gre_tunnel_validate(tb, data);
  }
  
  
  static void ip6gre_netlink_parms(struct nlattr *data[],
  				struct __ip6_tnl_parm *parms)
  {
  	memset(parms, 0, sizeof(*parms));
  
  	if (!data)
  		return;
  
  	if (data[IFLA_GRE_LINK])
  		parms->link = nla_get_u32(data[IFLA_GRE_LINK]);
  
  	if (data[IFLA_GRE_IFLAGS])

  		parms->i_flags = gre_flags_to_tnl_flags(
  				nla_get_be16(data[IFLA_GRE_IFLAGS]));

  
  	if (data[IFLA_GRE_OFLAGS])

  		parms->o_flags = gre_flags_to_tnl_flags(
  				nla_get_be16(data[IFLA_GRE_OFLAGS]));

  
  	if (data[IFLA_GRE_IKEY])
  		parms->i_key = nla_get_be32(data[IFLA_GRE_IKEY]);
  
  	if (data[IFLA_GRE_OKEY])
  		parms->o_key = nla_get_be32(data[IFLA_GRE_OKEY]);
  
  	if (data[IFLA_GRE_LOCAL])

  		parms->laddr = nla_get_in6_addr(data[IFLA_GRE_LOCAL]);

  
  	if (data[IFLA_GRE_REMOTE])

  		parms->raddr = nla_get_in6_addr(data[IFLA_GRE_REMOTE]);

  
  	if (data[IFLA_GRE_TTL])
  		parms->hop_limit = nla_get_u8(data[IFLA_GRE_TTL]);
  
  	if (data[IFLA_GRE_ENCAP_LIMIT])
  		parms->encap_limit = nla_get_u8(data[IFLA_GRE_ENCAP_LIMIT]);
  
  	if (data[IFLA_GRE_FLOWINFO])

  		parms->flowinfo = nla_get_be32(data[IFLA_GRE_FLOWINFO]);

  
  	if (data[IFLA_GRE_FLAGS])
  		parms->flags = nla_get_u32(data[IFLA_GRE_FLAGS]);
  }
  
  static int ip6gre_tap_init(struct net_device *dev)
  {
  	struct ip6_tnl *tunnel;

  	int ret;

  	ret = ip6gre_tunnel_init_common(dev);
  	if (ret)
  		return ret;

  	dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;

  	tunnel = netdev_priv(dev);

  
  	ip6gre_tnl_link_config(tunnel, 1);

  	return 0;
  }
  
  static const struct net_device_ops ip6gre_tap_netdev_ops = {
  	.ndo_init = ip6gre_tap_init,
  	.ndo_uninit = ip6gre_tunnel_uninit,
  	.ndo_start_xmit = ip6gre_tunnel_xmit,
  	.ndo_set_mac_address = eth_mac_addr,
  	.ndo_validate_addr = eth_validate_addr,

  	.ndo_change_mtu = ip6_tnl_change_mtu,

  	.ndo_get_stats64 = ip_tunnel_get_stats64,

  	.ndo_get_iflink = ip6_tnl_get_iflink,

  };

  #define GRE6_FEATURES (NETIF_F_SG |		\
  		       NETIF_F_FRAGLIST |	\
  		       NETIF_F_HIGHDMA |		\
  		       NETIF_F_HW_CSUM)

  static void ip6gre_tap_setup(struct net_device *dev)
  {
  
  	ether_setup(dev);
  
  	dev->netdev_ops = &ip6gre_tap_netdev_ops;
  	dev->destructor = ip6gre_dev_free;

  	dev->features |= NETIF_F_NETNS_LOCAL;

  	dev->priv_flags &= ~IFF_TX_SKB_SHARING;

  	dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;

  }

  static bool ip6gre_netlink_encap_parms(struct nlattr *data[],
  				       struct ip_tunnel_encap *ipencap)
  {
  	bool ret = false;
  
  	memset(ipencap, 0, sizeof(*ipencap));
  
  	if (!data)
  		return ret;
  
  	if (data[IFLA_GRE_ENCAP_TYPE]) {
  		ret = true;
  		ipencap->type = nla_get_u16(data[IFLA_GRE_ENCAP_TYPE]);
  	}
  
  	if (data[IFLA_GRE_ENCAP_FLAGS]) {
  		ret = true;
  		ipencap->flags = nla_get_u16(data[IFLA_GRE_ENCAP_FLAGS]);
  	}
  
  	if (data[IFLA_GRE_ENCAP_SPORT]) {
  		ret = true;
  		ipencap->sport = nla_get_be16(data[IFLA_GRE_ENCAP_SPORT]);
  	}
  
  	if (data[IFLA_GRE_ENCAP_DPORT]) {
  		ret = true;
  		ipencap->dport = nla_get_be16(data[IFLA_GRE_ENCAP_DPORT]);
  	}
  
  	return ret;
  }

  static int ip6gre_newlink(struct net *src_net, struct net_device *dev,
  	struct nlattr *tb[], struct nlattr *data[])
  {
  	struct ip6_tnl *nt;
  	struct net *net = dev_net(dev);
  	struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);

  	struct ip_tunnel_encap ipencap;

  	int err;
  
  	nt = netdev_priv(dev);

  
  	if (ip6gre_netlink_encap_parms(data, &ipencap)) {
  		int err = ip6_tnl_encap_setup(nt, &ipencap);
  
  		if (err < 0)
  			return err;
  	}

  	ip6gre_netlink_parms(data, &nt->parms);
  
  	if (ip6gre_tunnel_find(net, &nt->parms, dev->type))
  		return -EEXIST;
  
  	if (dev->type == ARPHRD_ETHER && !tb[IFLA_ADDRESS])
  		eth_hw_addr_random(dev);
  
  	nt->dev = dev;

  	nt->net = dev_net(dev);

  	ip6gre_tnl_link_config(nt, !tb[IFLA_MTU]);

  	dev->features		|= GRE6_FEATURES;
  	dev->hw_features	|= GRE6_FEATURES;

  	if (!(nt->parms.o_flags & TUNNEL_SEQ)) {

  		/* TCP offload with GRE SEQ is not supported, nor
  		 * can we support 2 levels of outer headers requiring
  		 * an update.

  		 */

  		if (!(nt->parms.o_flags & TUNNEL_CSUM) ||
  		    (nt->encap.type == TUNNEL_ENCAP_NONE)) {
  			dev->features    |= NETIF_F_GSO_SOFTWARE;
  			dev->hw_features |= NETIF_F_GSO_SOFTWARE;
  		}

  
  		/* Can use a lockless transmit, unless we generate
  		 * output sequences
  		 */

  		dev->features |= NETIF_F_LLTX;

  	}

  
  	err = register_netdevice(dev);
  	if (err)
  		goto out;
  
  	dev_hold(dev);
  	ip6gre_tunnel_link(ign, nt);
  
  out:
  	return err;
  }
  
  static int ip6gre_changelink(struct net_device *dev, struct nlattr *tb[],
  			    struct nlattr *data[])
  {

  	struct ip6_tnl *t, *nt = netdev_priv(dev);
  	struct net *net = nt->net;

  	struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
  	struct __ip6_tnl_parm p;

  	struct ip_tunnel_encap ipencap;

  
  	if (dev == ign->fb_tunnel_dev)
  		return -EINVAL;

  	if (ip6gre_netlink_encap_parms(data, &ipencap)) {
  		int err = ip6_tnl_encap_setup(nt, &ipencap);
  
  		if (err < 0)
  			return err;
  	}

  	ip6gre_netlink_parms(data, &p);
  
  	t = ip6gre_tunnel_locate(net, &p, 0);
  
  	if (t) {
  		if (t->dev != dev)
  			return -EEXIST;
  	} else {
  		t = nt;

  	}

  	ip6gre_tunnel_unlink(ign, t);
  	ip6gre_tnl_change(t, &p, !tb[IFLA_MTU]);
  	ip6gre_tunnel_link(ign, t);

  	return 0;
  }

  static void ip6gre_dellink(struct net_device *dev, struct list_head *head)
  {
  	struct net *net = dev_net(dev);
  	struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
  
  	if (dev != ign->fb_tunnel_dev)
  		unregister_netdevice_queue(dev, head);
  }

  static size_t ip6gre_get_size(const struct net_device *dev)
  {
  	return
  		/* IFLA_GRE_LINK */
  		nla_total_size(4) +
  		/* IFLA_GRE_IFLAGS */
  		nla_total_size(2) +
  		/* IFLA_GRE_OFLAGS */
  		nla_total_size(2) +
  		/* IFLA_GRE_IKEY */
  		nla_total_size(4) +
  		/* IFLA_GRE_OKEY */
  		nla_total_size(4) +
  		/* IFLA_GRE_LOCAL */

  		nla_total_size(sizeof(struct in6_addr)) +

  		/* IFLA_GRE_REMOTE */

  		nla_total_size(sizeof(struct in6_addr)) +

  		/* IFLA_GRE_TTL */
  		nla_total_size(1) +

  		/* IFLA_GRE_ENCAP_LIMIT */
  		nla_total_size(1) +
  		/* IFLA_GRE_FLOWINFO */
  		nla_total_size(4) +
  		/* IFLA_GRE_FLAGS */
  		nla_total_size(4) +

  		/* IFLA_GRE_ENCAP_TYPE */
  		nla_total_size(2) +
  		/* IFLA_GRE_ENCAP_FLAGS */
  		nla_total_size(2) +
  		/* IFLA_GRE_ENCAP_SPORT */
  		nla_total_size(2) +
  		/* IFLA_GRE_ENCAP_DPORT */
  		nla_total_size(2) +

  		0;
  }
  
  static int ip6gre_fill_info(struct sk_buff *skb, const struct net_device *dev)
  {
  	struct ip6_tnl *t = netdev_priv(dev);
  	struct __ip6_tnl_parm *p = &t->parms;
  
  	if (nla_put_u32(skb, IFLA_GRE_LINK, p->link) ||

  	    nla_put_be16(skb, IFLA_GRE_IFLAGS,
  			 gre_tnl_flags_to_gre_flags(p->i_flags)) ||
  	    nla_put_be16(skb, IFLA_GRE_OFLAGS,
  			 gre_tnl_flags_to_gre_flags(p->o_flags)) ||

  	    nla_put_be32(skb, IFLA_GRE_IKEY, p->i_key) ||
  	    nla_put_be32(skb, IFLA_GRE_OKEY, p->o_key) ||

  	    nla_put_in6_addr(skb, IFLA_GRE_LOCAL, &p->laddr) ||
  	    nla_put_in6_addr(skb, IFLA_GRE_REMOTE, &p->raddr) ||

  	    nla_put_u8(skb, IFLA_GRE_TTL, p->hop_limit) ||

  	    nla_put_u8(skb, IFLA_GRE_ENCAP_LIMIT, p->encap_limit) ||
  	    nla_put_be32(skb, IFLA_GRE_FLOWINFO, p->flowinfo) ||
  	    nla_put_u32(skb, IFLA_GRE_FLAGS, p->flags))
  		goto nla_put_failure;

  
  	if (nla_put_u16(skb, IFLA_GRE_ENCAP_TYPE,
  			t->encap.type) ||
  	    nla_put_be16(skb, IFLA_GRE_ENCAP_SPORT,
  			 t->encap.sport) ||
  	    nla_put_be16(skb, IFLA_GRE_ENCAP_DPORT,
  			 t->encap.dport) ||
  	    nla_put_u16(skb, IFLA_GRE_ENCAP_FLAGS,
  			t->encap.flags))
  		goto nla_put_failure;

  	return 0;
  
  nla_put_failure:
  	return -EMSGSIZE;
  }
  
  static const struct nla_policy ip6gre_policy[IFLA_GRE_MAX + 1] = {
  	[IFLA_GRE_LINK]        = { .type = NLA_U32 },
  	[IFLA_GRE_IFLAGS]      = { .type = NLA_U16 },
  	[IFLA_GRE_OFLAGS]      = { .type = NLA_U16 },
  	[IFLA_GRE_IKEY]        = { .type = NLA_U32 },
  	[IFLA_GRE_OKEY]        = { .type = NLA_U32 },
  	[IFLA_GRE_LOCAL]       = { .len = FIELD_SIZEOF(struct ipv6hdr, saddr) },
  	[IFLA_GRE_REMOTE]      = { .len = FIELD_SIZEOF(struct ipv6hdr, daddr) },
  	[IFLA_GRE_TTL]         = { .type = NLA_U8 },
  	[IFLA_GRE_ENCAP_LIMIT] = { .type = NLA_U8 },
  	[IFLA_GRE_FLOWINFO]    = { .type = NLA_U32 },
  	[IFLA_GRE_FLAGS]       = { .type = NLA_U32 },

  	[IFLA_GRE_ENCAP_TYPE]   = { .type = NLA_U16 },
  	[IFLA_GRE_ENCAP_FLAGS]  = { .type = NLA_U16 },
  	[IFLA_GRE_ENCAP_SPORT]  = { .type = NLA_U16 },
  	[IFLA_GRE_ENCAP_DPORT]  = { .type = NLA_U16 },

  };
  
  static struct rtnl_link_ops ip6gre_link_ops __read_mostly = {
  	.kind		= "ip6gre",
  	.maxtype	= IFLA_GRE_MAX,
  	.policy		= ip6gre_policy,
  	.priv_size	= sizeof(struct ip6_tnl),
  	.setup		= ip6gre_tunnel_setup,
  	.validate	= ip6gre_tunnel_validate,
  	.newlink	= ip6gre_newlink,
  	.changelink	= ip6gre_changelink,

  	.dellink	= ip6gre_dellink,

  	.get_size	= ip6gre_get_size,
  	.fill_info	= ip6gre_fill_info,

  	.get_link_net	= ip6_tnl_get_link_net,

  };
  
  static struct rtnl_link_ops ip6gre_tap_ops __read_mostly = {
  	.kind		= "ip6gretap",
  	.maxtype	= IFLA_GRE_MAX,
  	.policy		= ip6gre_policy,
  	.priv_size	= sizeof(struct ip6_tnl),
  	.setup		= ip6gre_tap_setup,
  	.validate	= ip6gre_tap_validate,
  	.newlink	= ip6gre_newlink,
  	.changelink	= ip6gre_changelink,
  	.get_size	= ip6gre_get_size,
  	.fill_info	= ip6gre_fill_info,

  	.get_link_net	= ip6_tnl_get_link_net,

  };
  
  /*
   *	And now the modules code and kernel interface.
   */
  
  static int __init ip6gre_init(void)
  {
  	int err;
  
  	pr_info("GRE over IPv6 tunneling driver
  ");
  
  	err = register_pernet_device(&ip6gre_net_ops);
  	if (err < 0)
  		return err;
  
  	err = inet6_add_protocol(&ip6gre_protocol, IPPROTO_GRE);
  	if (err < 0) {
  		pr_info("%s: can't add protocol
  ", __func__);
  		goto add_proto_failed;
  	}
  
  	err = rtnl_link_register(&ip6gre_link_ops);
  	if (err < 0)
  		goto rtnl_link_failed;
  
  	err = rtnl_link_register(&ip6gre_tap_ops);
  	if (err < 0)
  		goto tap_ops_failed;
  
  out:
  	return err;
  
  tap_ops_failed:
  	rtnl_link_unregister(&ip6gre_link_ops);
  rtnl_link_failed:
  	inet6_del_protocol(&ip6gre_protocol, IPPROTO_GRE);
  add_proto_failed:
  	unregister_pernet_device(&ip6gre_net_ops);
  	goto out;
  }
  
  static void __exit ip6gre_fini(void)
  {
  	rtnl_link_unregister(&ip6gre_tap_ops);
  	rtnl_link_unregister(&ip6gre_link_ops);
  	inet6_del_protocol(&ip6gre_protocol, IPPROTO_GRE);
  	unregister_pernet_device(&ip6gre_net_ops);
  }
  
  module_init(ip6gre_init);
  module_exit(ip6gre_fini);
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
  MODULE_DESCRIPTION("GRE over IPv6 tunneling device");
  MODULE_ALIAS_RTNL_LINK("ip6gre");

  MODULE_ALIAS_RTNL_LINK("ip6gretap");

  MODULE_ALIAS_NETDEV("ip6gre0");