// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   *	IPv6 virtual tunneling interface
   *
   *	Copyright (C) 2013 secunet Security Networks AG
   *
   *	Author:
   *	Steffen Klassert <steffen.klassert@secunet.com>
   *
   *	Based on:
   *	net/ipv6/ip6_tunnel.c

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

  #include <linux/etherdevice.h>

  #define IP6_VTI_HASH_SIZE_SHIFT  5
  #define IP6_VTI_HASH_SIZE (1 << IP6_VTI_HASH_SIZE_SHIFT)

  
  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, IP6_VTI_HASH_SIZE_SHIFT);

  }
  
  static int vti6_dev_init(struct net_device *dev);
  static void vti6_dev_setup(struct net_device *dev);
  static struct rtnl_link_ops vti6_link_ops __read_mostly;

  static unsigned int vti6_net_id __read_mostly;

  struct vti6_net {
  	/* the vti6 tunnel fallback device */
  	struct net_device *fb_tnl_dev;
  	/* lists for storing tunnels in use */

  	struct ip6_tnl __rcu *tnls_r_l[IP6_VTI_HASH_SIZE];

  	struct ip6_tnl __rcu *tnls_wc[1];
  	struct ip6_tnl __rcu **tnls[2];
  };

  #define for_each_vti6_tunnel_rcu(start) \
  	for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))
  
  /**
   * vti6_tnl_lookup - fetch tunnel matching the end-point addresses
   *   @net: network namespace
   *   @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
   **/
  static struct ip6_tnl *
  vti6_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 vti6_net *ip6n = net_generic(net, vti6_net_id);

  	struct in6_addr any;

  
  	for_each_vti6_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;
  	}

  
  	memset(&any, 0, sizeof(any));
  	hash = HASH(&any, local);
  	for_each_vti6_tunnel_rcu(ip6n->tnls_r_l[hash]) {
  		if (ipv6_addr_equal(local, &t->parms.laddr) &&
  		    (t->dev->flags & IFF_UP))
  			return t;
  	}
  
  	hash = HASH(remote, &any);
  	for_each_vti6_tunnel_rcu(ip6n->tnls_r_l[hash]) {
  		if (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;
  }
  
  /**
   * vti6_tnl_bucket - get head of list matching given tunnel parameters
   *   @p: parameters containing tunnel end-points
   *
   * Description:
   *   vti6_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 **
  vti6_tnl_bucket(struct vti6_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];
  }
  
  static void
  vti6_tnl_link(struct vti6_net *ip6n, struct ip6_tnl *t)
  {
  	struct ip6_tnl __rcu **tp = vti6_tnl_bucket(ip6n, &t->parms);
  
  	rcu_assign_pointer(t->next , rtnl_dereference(*tp));
  	rcu_assign_pointer(*tp, t);
  }
  
  static void
  vti6_tnl_unlink(struct vti6_net *ip6n, struct ip6_tnl *t)
  {
  	struct ip6_tnl __rcu **tp;
  	struct ip6_tnl *iter;
  
  	for (tp = vti6_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 vti6_dev_free(struct net_device *dev)
  {
  	free_percpu(dev->tstats);

  }
  
  static int vti6_tnl_create2(struct net_device *dev)
  {
  	struct ip6_tnl *t = netdev_priv(dev);
  	struct net *net = dev_net(dev);
  	struct vti6_net *ip6n = net_generic(net, vti6_net_id);
  	int err;

  	dev->rtnl_link_ops = &vti6_link_ops;

  	err = register_netdevice(dev);
  	if (err < 0)
  		goto out;
  
  	strcpy(t->parms.name, dev->name);

  
  	dev_hold(dev);
  	vti6_tnl_link(ip6n, t);
  
  	return 0;
  
  out:
  	return err;
  }
  
  static struct ip6_tnl *vti6_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]) {
  		if (!dev_valid_name(p->name))
  			goto failed;

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

  	} else {

  		sprintf(name, "ip6_vti%%d");

  	}

  	dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN, vti6_dev_setup);

  	if (!dev)

  		goto failed;
  
  	dev_net_set(dev, net);
  
  	t = netdev_priv(dev);
  	t->parms = *p;
  	t->net = dev_net(dev);
  
  	err = vti6_tnl_create2(dev);
  	if (err < 0)
  		goto failed_free;
  
  	return t;
  
  failed_free:

  	free_netdev(dev);

  failed:
  	return NULL;
  }
  
  /**
   * vti6_locate - find or create tunnel matching given parameters
   *   @net: network namespace
   *   @p: tunnel parameters
   *   @create: != 0 if allowed to create new tunnel if no match found
   *
   * Description:
   *   vti6_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 *vti6_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 vti6_net *ip6n = net_generic(net, vti6_net_id);
  
  	for (tp = vti6_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)) {
  			if (create)
  				return NULL;

  			return t;

  		}

  	}
  	if (!create)
  		return NULL;
  	return vti6_tnl_create(net, p);
  }
  
  /**
   * vti6_dev_uninit - tunnel device uninitializer
   *   @dev: the device to be destroyed
   *
   * Description:
   *   vti6_dev_uninit() removes tunnel from its list
   **/
  static void vti6_dev_uninit(struct net_device *dev)
  {
  	struct ip6_tnl *t = netdev_priv(dev);

  	struct vti6_net *ip6n = net_generic(t->net, vti6_net_id);

  
  	if (dev == ip6n->fb_tnl_dev)
  		RCU_INIT_POINTER(ip6n->tnls_wc[0], NULL);
  	else
  		vti6_tnl_unlink(ip6n, t);

  	dev_put(dev);
  }

  static int vti6_input_proto(struct sk_buff *skb, int nexthdr, __be32 spi,
  			    int encap_type)

  {
  	struct ip6_tnl *t;
  	const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
  
  	rcu_read_lock();

  	t = vti6_tnl_lookup(dev_net(skb->dev), &ipv6h->saddr, &ipv6h->daddr);

  	if (t) {

  		if (t->parms.proto != IPPROTO_IPV6 && t->parms.proto != 0) {
  			rcu_read_unlock();
  			goto discard;
  		}
  
  		if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
  			rcu_read_unlock();

  			goto discard;

  		}

  		ipv6h = ipv6_hdr(skb);

  		if (!ip6_tnl_rcv_ctl(t, &ipv6h->daddr, &ipv6h->saddr)) {
  			t->dev->stats.rx_dropped++;
  			rcu_read_unlock();
  			goto discard;
  		}

  		rcu_read_unlock();

  		XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = t;
  		XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
  		XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
  		return xfrm_input(skb, nexthdr, spi, encap_type);

  	}
  	rcu_read_unlock();

  	return -EINVAL;

  discard:
  	kfree_skb(skb);
  	return 0;
  }

  static int vti6_rcv(struct sk_buff *skb)
  {
  	int nexthdr = skb_network_header(skb)[IP6CB(skb)->nhoff];
  
  	return vti6_input_proto(skb, nexthdr, 0, 0);
  }

  static int vti6_rcv_cb(struct sk_buff *skb, int err)
  {
  	unsigned short family;
  	struct net_device *dev;

  	struct xfrm_state *x;

  	const struct xfrm_mode *inner_mode;

  	struct ip6_tnl *t = XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6;

  	u32 orig_mark = skb->mark;
  	int ret;

  
  	if (!t)
  		return 1;
  
  	dev = t->dev;
  
  	if (err) {
  		dev->stats.rx_errors++;
  		dev->stats.rx_dropped++;
  
  		return 0;
  	}
  
  	x = xfrm_input_state(skb);

  	inner_mode = &x->inner_mode;

  
  	if (x->sel.family == AF_UNSPEC) {
  		inner_mode = xfrm_ip2inner_mode(x, XFRM_MODE_SKB_CB(skb)->protocol);
  		if (inner_mode == NULL) {
  			XFRM_INC_STATS(dev_net(skb->dev),
  				       LINUX_MIB_XFRMINSTATEMODEERROR);
  			return -EINVAL;
  		}
  	}

  	family = inner_mode->family;

  	skb->mark = be32_to_cpu(t->parms.i_key);
  	ret = xfrm_policy_check(NULL, XFRM_POLICY_IN, skb, family);
  	skb->mark = orig_mark;
  
  	if (!ret)

  		return -EPERM;
  
  	skb_scrub_packet(skb, !net_eq(t->net, dev_net(skb->dev)));
  	skb->dev = dev;

  	dev_sw_netstats_rx_add(dev, skb->len);

  
  	return 0;
  }

  /**
   * vti6_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
  vti6_addr_conflict(const struct ip6_tnl *t, const struct ipv6hdr *hdr)
  {
  	return ipv6_addr_equal(&t->parms.raddr, &hdr->saddr);
  }

  static bool vti6_state_check(const struct xfrm_state *x,
  			     const struct in6_addr *dst,
  			     const struct in6_addr *src)
  {
  	xfrm_address_t *daddr = (xfrm_address_t *)dst;
  	xfrm_address_t *saddr = (xfrm_address_t *)src;
  
  	/* if there is no transform then this tunnel is not functional.
  	 * Or if the xfrm is not mode tunnel.
  	 */
  	if (!x || x->props.mode != XFRM_MODE_TUNNEL ||
  	    x->props.family != AF_INET6)
  		return false;
  
  	if (ipv6_addr_any(dst))
  		return xfrm_addr_equal(saddr, &x->props.saddr, AF_INET6);
  
  	if (!xfrm_state_addr_check(x, daddr, saddr, AF_INET6))
  		return false;
  
  	return true;
  }

  /**
   * vti6_xmit - send a packet
   *   @skb: the outgoing socket buffer
   *   @dev: the outgoing tunnel device

   *   @fl: the flow informations for the xfrm_lookup

   **/

  static int
  vti6_xmit(struct sk_buff *skb, struct net_device *dev, struct flowi *fl)

  {

  	struct ip6_tnl *t = netdev_priv(dev);
  	struct net_device_stats *stats = &t->dev->stats;

  	struct dst_entry *dst = skb_dst(skb);

  	struct net_device *tdev;

  	struct xfrm_state *x;

  	int pkt_len = skb->len;

  	int err = -1;

  	int mtu;

  	if (!dst) {

  		switch (skb->protocol) {
  		case htons(ETH_P_IP): {
  			struct rtable *rt;
  
  			fl->u.ip4.flowi4_oif = dev->ifindex;
  			fl->u.ip4.flowi4_flags |= FLOWI_FLAG_ANYSRC;
  			rt = __ip_route_output_key(dev_net(dev), &fl->u.ip4);
  			if (IS_ERR(rt))
  				goto tx_err_link_failure;
  			dst = &rt->dst;
  			skb_dst_set(skb, dst);
  			break;
  		}
  		case htons(ETH_P_IPV6):
  			fl->u.ip6.flowi6_oif = dev->ifindex;
  			fl->u.ip6.flowi6_flags |= FLOWI_FLAG_ANYSRC;
  			dst = ip6_route_output(dev_net(dev), NULL, &fl->u.ip6);
  			if (dst->error) {
  				dst_release(dst);
  				dst = NULL;
  				goto tx_err_link_failure;
  			}
  			skb_dst_set(skb, dst);
  			break;
  		default:

  			goto tx_err_link_failure;
  		}

  	}

  	dst_hold(dst);

  	dst = xfrm_lookup_route(t->net, dst, fl, NULL, 0);

  	if (IS_ERR(dst)) {
  		err = PTR_ERR(dst);
  		dst = NULL;
  		goto tx_err_link_failure;

  	}

  	if (dst->flags & DST_XFRM_QUEUE)
  		goto queued;

  	x = dst->xfrm;
  	if (!vti6_state_check(x, &t->parms.raddr, &t->parms.laddr))
  		goto tx_err_link_failure;
  
  	if (!ip6_tnl_xmit_ctl(t, (const struct in6_addr *)&x->props.saddr,
  			      (const struct in6_addr *)&x->id.daddr))

  		goto tx_err_link_failure;
  
  	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);

  	if (skb->len > mtu) {

  		skb_dst_update_pmtu_no_confirm(skb, mtu);

  		if (skb->protocol == htons(ETH_P_IPV6)) {
  			if (mtu < IPV6_MIN_MTU)
  				mtu = IPV6_MIN_MTU;

  			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);

  		} else {

  			icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
  				  htonl(mtu));

  		}

  		err = -EMSGSIZE;
  		goto tx_err_dst_release;

  	}

  queued:

  	skb_scrub_packet(skb, !net_eq(t->net, dev_net(dev)));
  	skb_dst_set(skb, dst);
  	skb->dev = skb_dst(skb)->dev;

  	err = dst_output(t->net, skb->sk, skb);

  	if (net_xmit_eval(err) == 0)
  		err = pkt_len;
  	iptunnel_xmit_stats(dev, err);

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

  	dst_release(dst);

  	return err;
  }
  
  static netdev_tx_t
  vti6_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;

  	struct flowi fl;

  	int ret;

  	if (!pskb_inet_may_pull(skb))
  		goto tx_err;

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

  	switch (skb->protocol) {
  	case htons(ETH_P_IPV6):

  		if ((t->parms.proto != IPPROTO_IPV6 && t->parms.proto != 0) ||

  		    vti6_addr_conflict(t, ipv6_hdr(skb)))

  			goto tx_err;
  
  		xfrm_decode_session(skb, &fl, AF_INET6);
  		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
  		break;
  	case htons(ETH_P_IP):
  		xfrm_decode_session(skb, &fl, AF_INET);
  		memset(IPCB(skb), 0, sizeof(*IPCB(skb)));

  		break;
  	default:
  		goto tx_err;
  	}

  	/* override mark with tunnel output key */
  	fl.flowi_mark = be32_to_cpu(t->parms.o_key);

  	ret = vti6_xmit(skb, dev, &fl);

  	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 int vti6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
  		    u8 type, u8 code, int offset, __be32 info)
  {
  	__be32 spi;

  	__u32 mark;

  	struct xfrm_state *x;
  	struct ip6_tnl *t;
  	struct ip_esp_hdr *esph;
  	struct ip_auth_hdr *ah;
  	struct ip_comp_hdr *ipch;
  	struct net *net = dev_net(skb->dev);
  	const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data;
  	int protocol = iph->nexthdr;
  
  	t = vti6_tnl_lookup(dev_net(skb->dev), &iph->daddr, &iph->saddr);
  	if (!t)
  		return -1;

  	mark = be32_to_cpu(t->parms.o_key);

  	switch (protocol) {
  	case IPPROTO_ESP:
  		esph = (struct ip_esp_hdr *)(skb->data + offset);
  		spi = esph->spi;
  		break;
  	case IPPROTO_AH:
  		ah = (struct ip_auth_hdr *)(skb->data + offset);
  		spi = ah->spi;
  		break;
  	case IPPROTO_COMP:
  		ipch = (struct ip_comp_hdr *)(skb->data + offset);
  		spi = htonl(ntohs(ipch->cpi));
  		break;
  	default:
  		return 0;
  	}
  
  	if (type != ICMPV6_PKT_TOOBIG &&
  	    type != NDISC_REDIRECT)
  		return 0;

  	x = xfrm_state_lookup(net, mark, (const xfrm_address_t *)&iph->daddr,

  			      spi, protocol, AF_INET6);
  	if (!x)
  		return 0;
  
  	if (type == NDISC_REDIRECT)

  		ip6_redirect(skb, net, skb->dev->ifindex, 0,
  			     sock_net_uid(net, NULL));

  	else

  		ip6_update_pmtu(skb, net, info, 0, 0, sock_net_uid(net, NULL));

  	xfrm_state_put(x);
  
  	return 0;
  }

  static void vti6_link_config(struct ip6_tnl *t, bool keep_mtu)

  {

  	struct net_device *dev = t->dev;
  	struct __ip6_tnl_parm *p = &t->parms;

  	struct net_device *tdev = NULL;

  	int mtu;

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

  	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;

  	if (keep_mtu && dev->mtu) {
  		dev->mtu = clamp(dev->mtu, dev->min_mtu, dev->max_mtu);
  		return;
  	}

  	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, NULL, strict);

  
  		if (rt)
  			tdev = rt->dst.dev;
  		ip6_rt_put(rt);
  	}
  
  	if (!tdev && p->link)
  		tdev = __dev_get_by_index(t->net, p->link);
  
  	if (tdev)

  		mtu = tdev->mtu - sizeof(struct ipv6hdr);
  	else
  		mtu = ETH_DATA_LEN - LL_MAX_HEADER - sizeof(struct ipv6hdr);

  	dev->mtu = max_t(int, mtu, IPV4_MIN_MTU);

  }
  
  /**
   * vti6_tnl_change - update the tunnel parameters
   *   @t: tunnel to be changed
   *   @p: tunnel configuration parameters

   *   @keep_mtu: MTU was set from userspace, don't re-compute it

   *
   * Description:
   *   vti6_tnl_change() updates the tunnel parameters
   **/
  static int

  vti6_tnl_change(struct ip6_tnl *t, const struct __ip6_tnl_parm *p,
  		bool keep_mtu)

  {
  	t->parms.laddr = p->laddr;
  	t->parms.raddr = p->raddr;
  	t->parms.link = p->link;
  	t->parms.i_key = p->i_key;
  	t->parms.o_key = p->o_key;
  	t->parms.proto = p->proto;

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

  	dst_cache_reset(&t->dst_cache);

  	vti6_link_config(t, keep_mtu);

  	return 0;
  }

  static int vti6_update(struct ip6_tnl *t, struct __ip6_tnl_parm *p,
  		       bool keep_mtu)

  {
  	struct net *net = dev_net(t->dev);
  	struct vti6_net *ip6n = net_generic(net, vti6_net_id);
  	int err;
  
  	vti6_tnl_unlink(ip6n, t);
  	synchronize_net();

  	err = vti6_tnl_change(t, p, keep_mtu);

  	vti6_tnl_link(ip6n, t);
  	netdev_state_change(t->dev);
  	return err;
  }
  
  static void
  vti6_parm_from_user(struct __ip6_tnl_parm *p, const struct ip6_tnl_parm2 *u)
  {
  	p->laddr = u->laddr;
  	p->raddr = u->raddr;
  	p->link = u->link;
  	p->i_key = u->i_key;
  	p->o_key = u->o_key;
  	p->proto = u->proto;
  
  	memcpy(p->name, u->name, sizeof(u->name));
  }
  
  static void
  vti6_parm_to_user(struct ip6_tnl_parm2 *u, const struct __ip6_tnl_parm *p)
  {
  	u->laddr = p->laddr;
  	u->raddr = p->raddr;
  	u->link = p->link;
  	u->i_key = p->i_key;
  	u->o_key = p->o_key;

  	if (u->i_key)
  		u->i_flags |= GRE_KEY;
  	if (u->o_key)
  		u->o_flags |= GRE_KEY;

  	u->proto = p->proto;
  
  	memcpy(u->name, p->name, sizeof(u->name));
  }
  
  /**

   * vti6_ioctl - configure vti6 tunnels from userspace

   *   @dev: virtual device associated with tunnel
   *   @ifr: parameters passed from userspace
   *   @cmd: command to be performed
   *
   * Description:
   *   vti6_ioctl() is used for managing vti6 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 "ip6_vti0", 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
  vti6_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 = NULL;
  	struct net *net = dev_net(dev);
  	struct vti6_net *ip6n = net_generic(net, vti6_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;
  			}
  			vti6_parm_from_user(&p1, &p);
  			t = vti6_locate(net, &p1, 0);
  		} else {
  			memset(&p, 0, sizeof(p));
  		}

  		if (!t)

  			t = netdev_priv(dev);
  		vti6_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 != 0)
  			break;
  		vti6_parm_from_user(&p1, &p);
  		t = vti6_locate(net, &p1, cmd == SIOCADDTUNNEL);
  		if (dev != ip6n->fb_tnl_dev && cmd == SIOCCHGTUNNEL) {

  			if (t) {

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

  			err = vti6_update(t, &p1, false);

  		}
  		if (t) {
  			err = 0;
  			vti6_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;
  			vti6_parm_from_user(&p1, &p);
  			t = vti6_locate(net, &p1, 0);

  			if (!t)

  				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;
  }

  static const struct net_device_ops vti6_netdev_ops = {

  	.ndo_init	= vti6_dev_init,

  	.ndo_uninit	= vti6_dev_uninit,
  	.ndo_start_xmit = vti6_tnl_xmit,
  	.ndo_do_ioctl	= vti6_ioctl,

  	.ndo_get_stats64 = ip_tunnel_get_stats64,

  	.ndo_get_iflink = ip6_tnl_get_iflink,

  };
  
  /**
   * vti6_dev_setup - setup virtual tunnel device
   *   @dev: virtual device associated with tunnel
   *
   * Description:
   *   Initialize function pointers and device parameters
   **/
  static void vti6_dev_setup(struct net_device *dev)
  {

  	dev->netdev_ops = &vti6_netdev_ops;

  	dev->header_ops = &ip_tunnel_header_ops;

  	dev->needs_free_netdev = true;
  	dev->priv_destructor = vti6_dev_free;

  
  	dev->type = ARPHRD_TUNNEL6;

  	dev->min_mtu = IPV4_MIN_MTU;

  	dev->max_mtu = IP_MAX_MTU - sizeof(struct ipv6hdr);

  	dev->flags |= IFF_NOARP;
  	dev->addr_len = sizeof(struct in6_addr);

  	netif_keep_dst(dev);

  	/* This perm addr will be used as interface identifier by IPv6 */
  	dev->addr_assign_type = NET_ADDR_RANDOM;
  	eth_random_addr(dev->perm_addr);

  }
  
  /**
   * vti6_dev_init_gen - general initializer for all tunnel devices
   *   @dev: virtual device associated with tunnel
   **/
  static inline int vti6_dev_init_gen(struct net_device *dev)
  {
  	struct ip6_tnl *t = netdev_priv(dev);
  
  	t->dev = dev;
  	t->net = dev_net(dev);

  	dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);

  	if (!dev->tstats)
  		return -ENOMEM;
  	return 0;
  }
  
  /**
   * vti6_dev_init - initializer for all non fallback tunnel devices
   *   @dev: virtual device associated with tunnel
   **/
  static int vti6_dev_init(struct net_device *dev)
  {
  	struct ip6_tnl *t = netdev_priv(dev);
  	int err = vti6_dev_init_gen(dev);
  
  	if (err)
  		return err;

  	vti6_link_config(t, true);

  	return 0;
  }
  
  /**
   * vti6_fb_tnl_dev_init - initializer for fallback tunnel device
   *   @dev: fallback device
   *
   * Return: 0
   **/
  static int __net_init vti6_fb_tnl_dev_init(struct net_device *dev)
  {
  	struct ip6_tnl *t = netdev_priv(dev);
  	struct net *net = dev_net(dev);
  	struct vti6_net *ip6n = net_generic(net, vti6_net_id);

  
  	t->parms.proto = IPPROTO_IPV6;
  	dev_hold(dev);

  	rcu_assign_pointer(ip6n->tnls_wc[0], t);
  	return 0;
  }

  static int vti6_validate(struct nlattr *tb[], struct nlattr *data[],
  			 struct netlink_ext_ack *extack)

  {
  	return 0;
  }
  
  static void vti6_netlink_parms(struct nlattr *data[],
  			       struct __ip6_tnl_parm *parms)
  {
  	memset(parms, 0, sizeof(*parms));
  
  	if (!data)
  		return;
  
  	if (data[IFLA_VTI_LINK])
  		parms->link = nla_get_u32(data[IFLA_VTI_LINK]);
  
  	if (data[IFLA_VTI_LOCAL])

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

  
  	if (data[IFLA_VTI_REMOTE])

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

  
  	if (data[IFLA_VTI_IKEY])
  		parms->i_key = nla_get_be32(data[IFLA_VTI_IKEY]);
  
  	if (data[IFLA_VTI_OKEY])
  		parms->o_key = nla_get_be32(data[IFLA_VTI_OKEY]);

  
  	if (data[IFLA_VTI_FWMARK])
  		parms->fwmark = nla_get_u32(data[IFLA_VTI_FWMARK]);

  }
  
  static int vti6_newlink(struct net *src_net, struct net_device *dev,

  			struct nlattr *tb[], struct nlattr *data[],
  			struct netlink_ext_ack *extack)

  {
  	struct net *net = dev_net(dev);
  	struct ip6_tnl *nt;
  
  	nt = netdev_priv(dev);
  	vti6_netlink_parms(data, &nt->parms);
  
  	nt->parms.proto = IPPROTO_IPV6;
  
  	if (vti6_locate(net, &nt->parms, 0))
  		return -EEXIST;
  
  	return vti6_tnl_create2(dev);
  }

  static void vti6_dellink(struct net_device *dev, struct list_head *head)
  {
  	struct net *net = dev_net(dev);
  	struct vti6_net *ip6n = net_generic(net, vti6_net_id);
  
  	if (dev != ip6n->fb_tnl_dev)
  		unregister_netdevice_queue(dev, head);
  }

  static int vti6_changelink(struct net_device *dev, struct nlattr *tb[],

  			   struct nlattr *data[],
  			   struct netlink_ext_ack *extack)

  {
  	struct ip6_tnl *t;
  	struct __ip6_tnl_parm p;
  	struct net *net = dev_net(dev);
  	struct vti6_net *ip6n = net_generic(net, vti6_net_id);
  
  	if (dev == ip6n->fb_tnl_dev)
  		return -EINVAL;
  
  	vti6_netlink_parms(data, &p);
  
  	t = vti6_locate(net, &p, 0);
  
  	if (t) {
  		if (t->dev != dev)
  			return -EEXIST;
  	} else
  		t = netdev_priv(dev);

  	return vti6_update(t, &p, tb && tb[IFLA_MTU]);

  }
  
  static size_t vti6_get_size(const struct net_device *dev)
  {
  	return
  		/* IFLA_VTI_LINK */
  		nla_total_size(4) +
  		/* IFLA_VTI_LOCAL */
  		nla_total_size(sizeof(struct in6_addr)) +
  		/* IFLA_VTI_REMOTE */
  		nla_total_size(sizeof(struct in6_addr)) +
  		/* IFLA_VTI_IKEY */
  		nla_total_size(4) +
  		/* IFLA_VTI_OKEY */
  		nla_total_size(4) +

  		/* IFLA_VTI_FWMARK */
  		nla_total_size(4) +

  		0;
  }
  
  static int vti6_fill_info(struct sk_buff *skb, const struct net_device *dev)
  {
  	struct ip6_tnl *tunnel = netdev_priv(dev);
  	struct __ip6_tnl_parm *parm = &tunnel->parms;
  
  	if (nla_put_u32(skb, IFLA_VTI_LINK, parm->link) ||

  	    nla_put_in6_addr(skb, IFLA_VTI_LOCAL, &parm->laddr) ||
  	    nla_put_in6_addr(skb, IFLA_VTI_REMOTE, &parm->raddr) ||

  	    nla_put_be32(skb, IFLA_VTI_IKEY, parm->i_key) ||

  	    nla_put_be32(skb, IFLA_VTI_OKEY, parm->o_key) ||
  	    nla_put_u32(skb, IFLA_VTI_FWMARK, parm->fwmark))

  		goto nla_put_failure;
  	return 0;
  
  nla_put_failure:
  	return -EMSGSIZE;
  }
  
  static const struct nla_policy vti6_policy[IFLA_VTI_MAX + 1] = {
  	[IFLA_VTI_LINK]		= { .type = NLA_U32 },
  	[IFLA_VTI_LOCAL]	= { .len = sizeof(struct in6_addr) },
  	[IFLA_VTI_REMOTE]	= { .len = sizeof(struct in6_addr) },
  	[IFLA_VTI_IKEY]		= { .type = NLA_U32 },
  	[IFLA_VTI_OKEY]		= { .type = NLA_U32 },

  	[IFLA_VTI_FWMARK]	= { .type = NLA_U32 },

  };
  
  static struct rtnl_link_ops vti6_link_ops __read_mostly = {
  	.kind		= "vti6",
  	.maxtype	= IFLA_VTI_MAX,
  	.policy		= vti6_policy,
  	.priv_size	= sizeof(struct ip6_tnl),
  	.setup		= vti6_dev_setup,
  	.validate	= vti6_validate,
  	.newlink	= vti6_newlink,

  	.dellink	= vti6_dellink,

  	.changelink	= vti6_changelink,
  	.get_size	= vti6_get_size,
  	.fill_info	= vti6_fill_info,

  	.get_link_net	= ip6_tnl_get_link_net,

  };

  static void __net_exit vti6_destroy_tunnels(struct vti6_net *ip6n,
  					    struct list_head *list)

  {
  	int h;
  	struct ip6_tnl *t;

  	for (h = 0; h < IP6_VTI_HASH_SIZE; h++) {

  		t = rtnl_dereference(ip6n->tnls_r_l[h]);

  		while (t) {

  			unregister_netdevice_queue(t->dev, list);

  			t = rtnl_dereference(t->next);
  		}
  	}
  
  	t = rtnl_dereference(ip6n->tnls_wc[0]);

  	if (t)
  		unregister_netdevice_queue(t->dev, list);

  }
  
  static int __net_init vti6_init_net(struct net *net)
  {
  	struct vti6_net *ip6n = net_generic(net, vti6_net_id);
  	struct ip6_tnl *t = NULL;
  	int err;
  
  	ip6n->tnls[0] = ip6n->tnls_wc;
  	ip6n->tnls[1] = ip6n->tnls_r_l;

  	if (!net_has_fallback_tunnels(net))
  		return 0;

  	err = -ENOMEM;
  	ip6n->fb_tnl_dev = alloc_netdev(sizeof(struct ip6_tnl), "ip6_vti0",

  					NET_NAME_UNKNOWN, vti6_dev_setup);

  
  	if (!ip6n->fb_tnl_dev)
  		goto err_alloc_dev;
  	dev_net_set(ip6n->fb_tnl_dev, net);

  	ip6n->fb_tnl_dev->rtnl_link_ops = &vti6_link_ops;

  
  	err = vti6_fb_tnl_dev_init(ip6n->fb_tnl_dev);
  	if (err < 0)
  		goto err_register;
  
  	err = register_netdev(ip6n->fb_tnl_dev);
  	if (err < 0)
  		goto err_register;
  
  	t = netdev_priv(ip6n->fb_tnl_dev);
  
  	strcpy(t->parms.name, ip6n->fb_tnl_dev->name);
  	return 0;
  
  err_register:

  	free_netdev(ip6n->fb_tnl_dev);

  err_alloc_dev:
  	return err;
  }

  static void __net_exit vti6_exit_batch_net(struct list_head *net_list)

  {

  	struct vti6_net *ip6n;
  	struct net *net;
  	LIST_HEAD(list);

  
  	rtnl_lock();

  	list_for_each_entry(net, net_list, exit_list) {
  		ip6n = net_generic(net, vti6_net_id);
  		vti6_destroy_tunnels(ip6n, &list);
  	}
  	unregister_netdevice_many(&list);

  	rtnl_unlock();
  }
  
  static struct pernet_operations vti6_net_ops = {
  	.init = vti6_init_net,

  	.exit_batch = vti6_exit_batch_net,

  	.id   = &vti6_net_id,
  	.size = sizeof(struct vti6_net),
  };

  static struct xfrm6_protocol vti_esp6_protocol __read_mostly = {
  	.handler	=	vti6_rcv,

  	.input_handler	=	vti6_input_proto,

  	.cb_handler	=	vti6_rcv_cb,
  	.err_handler	=	vti6_err,
  	.priority	=	100,
  };
  
  static struct xfrm6_protocol vti_ah6_protocol __read_mostly = {
  	.handler	=	vti6_rcv,

  	.input_handler	=	vti6_input_proto,

  	.cb_handler	=	vti6_rcv_cb,
  	.err_handler	=	vti6_err,
  	.priority	=	100,
  };
  
  static struct xfrm6_protocol vti_ipcomp6_protocol __read_mostly = {
  	.handler	=	vti6_rcv,

  	.input_handler	=	vti6_input_proto,

  	.cb_handler	=	vti6_rcv_cb,
  	.err_handler	=	vti6_err,
  	.priority	=	100,
  };

  #if IS_REACHABLE(CONFIG_INET6_XFRM_TUNNEL)

  static int vti6_rcv_tunnel(struct sk_buff *skb)
  {
  	const xfrm_address_t *saddr;
  	__be32 spi;
  
  	saddr = (const xfrm_address_t *)&ipv6_hdr(skb)->saddr;
  	spi = xfrm6_tunnel_spi_lookup(dev_net(skb->dev), saddr);
  
  	return vti6_input_proto(skb, IPPROTO_IPV6, spi, 0);
  }
  
  static struct xfrm6_tunnel vti_ipv6_handler __read_mostly = {
  	.handler	=	vti6_rcv_tunnel,
  	.cb_handler	=	vti6_rcv_cb,
  	.err_handler	=	vti6_err,
  	.priority	=	0,
  };

  
  static struct xfrm6_tunnel vti_ip6ip_handler __read_mostly = {
  	.handler	=	vti6_rcv_tunnel,
  	.cb_handler	=	vti6_rcv_cb,
  	.err_handler	=	vti6_err,
  	.priority	=	0,
  };

  #endif

  /**
   * vti6_tunnel_init - register protocol and reserve needed resources
   *
   * Return: 0 on success
   **/
  static int __init vti6_tunnel_init(void)
  {

  	const char *msg;
  	int err;

  	msg = "tunnel device";

  	err = register_pernet_device(&vti6_net_ops);
  	if (err < 0)

  		goto pernet_dev_failed;

  	msg = "tunnel protocols";

  	err = xfrm6_protocol_register(&vti_esp6_protocol, IPPROTO_ESP);

  	if (err < 0)
  		goto xfrm_proto_esp_failed;

  	err = xfrm6_protocol_register(&vti_ah6_protocol, IPPROTO_AH);

  	if (err < 0)
  		goto xfrm_proto_ah_failed;

  	err = xfrm6_protocol_register(&vti_ipcomp6_protocol, IPPROTO_COMP);

  	if (err < 0)
  		goto xfrm_proto_comp_failed;

  #if IS_REACHABLE(CONFIG_INET6_XFRM_TUNNEL)

  	msg = "ipv6 tunnel";
  	err = xfrm6_tunnel_register(&vti_ipv6_handler, AF_INET6);
  	if (err < 0)

  		goto vti_tunnel_ipv6_failed;

  	err = xfrm6_tunnel_register(&vti_ip6ip_handler, AF_INET);

  	if (err < 0)
  		goto vti_tunnel_ip6ip_failed;

  #endif

  	msg = "netlink interface";

  	err = rtnl_link_register(&vti6_link_ops);
  	if (err < 0)
  		goto rtnl_link_failed;
  
  	return 0;
  
  rtnl_link_failed:

  #if IS_REACHABLE(CONFIG_INET6_XFRM_TUNNEL)

  	err = xfrm6_tunnel_deregister(&vti_ip6ip_handler, AF_INET);

  vti_tunnel_ip6ip_failed:

  	err = xfrm6_tunnel_deregister(&vti_ipv6_handler, AF_INET6);

  vti_tunnel_ipv6_failed:

  #endif

  	xfrm6_protocol_deregister(&vti_ipcomp6_protocol, IPPROTO_COMP);

  xfrm_proto_comp_failed:

  	xfrm6_protocol_deregister(&vti_ah6_protocol, IPPROTO_AH);

  xfrm_proto_ah_failed:

  	xfrm6_protocol_deregister(&vti_esp6_protocol, IPPROTO_ESP);

  xfrm_proto_esp_failed:

  	unregister_pernet_device(&vti6_net_ops);

  pernet_dev_failed:
  	pr_err("vti6 init: failed to register %s
  ", msg);

  	return err;
  }
  
  /**
   * vti6_tunnel_cleanup - free resources and unregister protocol
   **/
  static void __exit vti6_tunnel_cleanup(void)
  {
  	rtnl_link_unregister(&vti6_link_ops);

  #if IS_REACHABLE(CONFIG_INET6_XFRM_TUNNEL)

  	xfrm6_tunnel_deregister(&vti_ip6ip_handler, AF_INET);

  	xfrm6_tunnel_deregister(&vti_ipv6_handler, AF_INET6);
  #endif

  	xfrm6_protocol_deregister(&vti_ipcomp6_protocol, IPPROTO_COMP);
  	xfrm6_protocol_deregister(&vti_ah6_protocol, IPPROTO_AH);
  	xfrm6_protocol_deregister(&vti_esp6_protocol, IPPROTO_ESP);

  	unregister_pernet_device(&vti6_net_ops);
  }
  
  module_init(vti6_tunnel_init);
  module_exit(vti6_tunnel_cleanup);
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_RTNL_LINK("vti6");
  MODULE_ALIAS_NETDEV("ip6_vti0");
  MODULE_AUTHOR("Steffen Klassert");
  MODULE_DESCRIPTION("IPv6 virtual tunnel interface");