/*
 *	Linux NET3: IP/IP protocol decoder modified to support
 *		    virtual tunnel interface
 *
 *	Authors:
 *		Saurabh Mohan (saurabh.mohan@vyatta.com) 05/07/2012
 *
 *	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.
 *
 */

/*
   This version of net/ipv4/ip_vti.c is cloned of net/ipv4/ipip.c

   For comments look at net/ipv4/ip_gre.c --ANK
 */


#include <linux/capability.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.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/mroute.h>
#include <linux/init.h>
#include <linux/netfilter_ipv4.h>
#include <linux/if_ether.h>

#include <net/sock.h>
#include <net/ip.h>
#include <net/icmp.h>
#include <net/ip_tunnels.h>
#include <net/inet_ecn.h>
#include <net/xfrm.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>

#define HASH_SIZE  16
#define HASH(addr) (((__force u32)addr^((__force u32)addr>>4))&(HASH_SIZE-1))

static struct rtnl_link_ops vti_link_ops __read_mostly;

static int vti_net_id __read_mostly;
struct vti_net {
	struct ip_tunnel __rcu *tunnels_r_l[HASH_SIZE];
	struct ip_tunnel __rcu *tunnels_r[HASH_SIZE];
	struct ip_tunnel __rcu *tunnels_l[HASH_SIZE];
	struct ip_tunnel __rcu *tunnels_wc[1];
	struct ip_tunnel __rcu **tunnels[4];

	struct net_device *fb_tunnel_dev;
};

static int vti_fb_tunnel_init(struct net_device *dev);
static int vti_tunnel_init(struct net_device *dev);
static void vti_tunnel_setup(struct net_device *dev);
static void vti_dev_free(struct net_device *dev);
static int vti_tunnel_bind_dev(struct net_device *dev);

#define VTI_XMIT(stats1, stats2) do {				\
	int err;						\
	int pkt_len = skb->len;					\
	err = dst_output(skb);					\
	if (net_xmit_eval(err) == 0) {				\
		u64_stats_update_begin(&(stats1)->syncp);	\
		(stats1)->tx_bytes += pkt_len;			\
		(stats1)->tx_packets++;				\
		u64_stats_update_end(&(stats1)->syncp);		\
	} else {						\
		(stats2)->tx_errors++;				\
		(stats2)->tx_aborted_errors++;			\
	}							\
} while (0)


static struct ip_tunnel *vti_tunnel_lookup(struct net *net,
					   __be32 remote, __be32 local)
{
	unsigned h0 = HASH(remote);
	unsigned h1 = HASH(local);
	struct ip_tunnel *t;
	struct vti_net *ipn = net_generic(net, vti_net_id);

	for_each_ip_tunnel_rcu(t, ipn->tunnels_r_l[h0 ^ h1])
		if (local == t->parms.iph.saddr &&
		    remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
			return t;
	for_each_ip_tunnel_rcu(t, ipn->tunnels_r[h0])
		if (remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
			return t;

	for_each_ip_tunnel_rcu(t, ipn->tunnels_l[h1])
		if (local == t->parms.iph.saddr && (t->dev->flags&IFF_UP))
			return t;

	for_each_ip_tunnel_rcu(t, ipn->tunnels_wc[0])
		if (t && (t->dev->flags&IFF_UP))
			return t;
	return NULL;
}

static struct ip_tunnel __rcu **__vti_bucket(struct vti_net *ipn,
					     struct ip_tunnel_parm *parms)
{
	__be32 remote = parms->iph.daddr;
	__be32 local = parms->iph.saddr;
	unsigned h = 0;
	int prio = 0;

	if (remote) {
		prio |= 2;
		h ^= HASH(remote);
	}
	if (local) {
		prio |= 1;
		h ^= HASH(local);
	}
	return &ipn->tunnels[prio][h];
}

static inline struct ip_tunnel __rcu **vti_bucket(struct vti_net *ipn,
						  struct ip_tunnel *t)
{
	return __vti_bucket(ipn, &t->parms);
}

static void vti_tunnel_unlink(struct vti_net *ipn, struct ip_tunnel *t)
{
	struct ip_tunnel __rcu **tp;
	struct ip_tunnel *iter;

	for (tp = vti_bucket(ipn, t);
	     (iter = rtnl_dereference(*tp)) != NULL;
	     tp = &iter->next) {
		if (t == iter) {
			rcu_assign_pointer(*tp, t->next);
			break;
		}
	}
}

static void vti_tunnel_link(struct vti_net *ipn, struct ip_tunnel *t)
{
	struct ip_tunnel __rcu **tp = vti_bucket(ipn, t);

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

static struct ip_tunnel *vti_tunnel_locate(struct net *net,
					   struct ip_tunnel_parm *parms,
					   int create)
{
	__be32 remote = parms->iph.daddr;
	__be32 local = parms->iph.saddr;
	struct ip_tunnel *t, *nt;
	struct ip_tunnel __rcu **tp;
	struct net_device *dev;
	char name[IFNAMSIZ];
	struct vti_net *ipn = net_generic(net, vti_net_id);

	for (tp = __vti_bucket(ipn, parms);
	     (t = rtnl_dereference(*tp)) != NULL;
	     tp = &t->next) {
		if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr)
			return t;
	}
	if (!create)
		return NULL;

	if (parms->name[0])
		strlcpy(name, parms->name, IFNAMSIZ);
	else
		strcpy(name, "vti%d");

	dev = alloc_netdev(sizeof(*t), name, vti_tunnel_setup);
	if (dev == NULL)
		return NULL;

	dev_net_set(dev, net);

	nt = netdev_priv(dev);
	nt->parms = *parms;
	dev->rtnl_link_ops = &vti_link_ops;

	vti_tunnel_bind_dev(dev);

	if (register_netdevice(dev) < 0)
		goto failed_free;

	dev_hold(dev);
	vti_tunnel_link(ipn, nt);
	return nt;

failed_free:
	free_netdev(dev);
	return NULL;
}

static void vti_tunnel_uninit(struct net_device *dev)
{
	struct net *net = dev_net(dev);
	struct vti_net *ipn = net_generic(net, vti_net_id);

	vti_tunnel_unlink(ipn, netdev_priv(dev));
	dev_put(dev);
}

static int vti_err(struct sk_buff *skb, u32 info)
{

	/* All the routers (except for Linux) return only
	 * 8 bytes of packet payload. It means, that precise relaying of
	 * ICMP in the real Internet is absolutely infeasible.
	 */
	struct iphdr *iph = (struct iphdr *)skb->data;
	const int type = icmp_hdr(skb)->type;
	const int code = icmp_hdr(skb)->code;
	struct ip_tunnel *t;
	int err;

	switch (type) {
	default:
	case ICMP_PARAMETERPROB:
		return 0;

	case ICMP_DEST_UNREACH:
		switch (code) {
		case ICMP_SR_FAILED:
		case ICMP_PORT_UNREACH:
			/* Impossible event. */
			return 0;
		default:
			/* All others are translated to HOST_UNREACH. */
			break;
		}
		break;
	case ICMP_TIME_EXCEEDED:
		if (code != ICMP_EXC_TTL)
			return 0;
		break;
	}

	err = -ENOENT;

	t = vti_tunnel_lookup(dev_net(skb->dev), iph->daddr, iph->saddr);
	if (t == NULL)
		goto out;

	if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
		ipv4_update_pmtu(skb, dev_net(skb->dev), info,
				 t->parms.link, 0, IPPROTO_IPIP, 0);
		err = 0;
		goto out;
	}

	err = 0;
	if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
		goto out;

	if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO))
		t->err_count++;
	else
		t->err_count = 1;
	t->err_time = jiffies;
out:
	return err;
}

/* We dont digest the packet therefore let the packet pass */
static int vti_rcv(struct sk_buff *skb)
{
	struct ip_tunnel *tunnel;
	const struct iphdr *iph = ip_hdr(skb);

	tunnel = vti_tunnel_lookup(dev_net(skb->dev), iph->saddr, iph->daddr);
	if (tunnel != NULL) {
		struct pcpu_tstats *tstats;

		if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
			return -1;

		tstats = this_cpu_ptr(tunnel->dev->tstats);
		u64_stats_update_begin(&tstats->syncp);
		tstats->rx_packets++;
		tstats->rx_bytes += skb->len;
		u64_stats_update_end(&tstats->syncp);

		skb->mark = 0;
		secpath_reset(skb);
		skb->dev = tunnel->dev;
		return 1;
	}

	return -1;
}

/* This function assumes it is being called from dev_queue_xmit()
 * and that skb is filled properly by that function.
 */

static netdev_tx_t vti_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct ip_tunnel *tunnel = netdev_priv(dev);
	struct pcpu_tstats *tstats;
	struct iphdr  *tiph = &tunnel->parms.iph;
	u8     tos;
	struct rtable *rt;		/* Route to the other host */
	struct net_device *tdev;	/* Device to other host */
	struct iphdr  *old_iph = ip_hdr(skb);
	__be32 dst = tiph->daddr;
	struct flowi4 fl4;

	if (skb->protocol != htons(ETH_P_IP))
		goto tx_error;

	tos = old_iph->tos;

	memset(&fl4, 0, sizeof(fl4));
	flowi4_init_output(&fl4, tunnel->parms.link,
			   be32_to_cpu(tunnel->parms.i_key), RT_TOS(tos),
			   RT_SCOPE_UNIVERSE,
			   IPPROTO_IPIP, 0,
			   dst, tiph->saddr, 0, 0);
	rt = ip_route_output_key(dev_net(dev), &fl4);
	if (IS_ERR(rt)) {
		dev->stats.tx_carrier_errors++;
		goto tx_error_icmp;
	}
	/* if there is no transform then this tunnel is not functional.
	 * Or if the xfrm is not mode tunnel.
	 */
	if (!rt->dst.xfrm ||
	    rt->dst.xfrm->props.mode != XFRM_MODE_TUNNEL) {
		dev->stats.tx_carrier_errors++;
		goto tx_error_icmp;
	}
	tdev = rt->dst.dev;

	if (tdev == dev) {
		ip_rt_put(rt);
		dev->stats.collisions++;
		goto tx_error;
	}

	if (tunnel->err_count > 0) {
		if (time_before(jiffies,
				tunnel->err_time + IPTUNNEL_ERR_TIMEO)) {
			tunnel->err_count--;
			dst_link_failure(skb);
		} else
			tunnel->err_count = 0;
	}

	memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
	skb_dst_drop(skb);
	skb_dst_set(skb, &rt->dst);
	nf_reset(skb);
	skb->dev = skb_dst(skb)->dev;

	tstats = this_cpu_ptr(dev->tstats);
	VTI_XMIT(tstats, &dev->stats);
	return NETDEV_TX_OK;

tx_error_icmp:
	dst_link_failure(skb);
tx_error:
	dev->stats.tx_errors++;
	dev_kfree_skb(skb);
	return NETDEV_TX_OK;
}

static int vti_tunnel_bind_dev(struct net_device *dev)
{
	struct net_device *tdev = NULL;
	struct ip_tunnel *tunnel;
	struct iphdr *iph;

	tunnel = netdev_priv(dev);
	iph = &tunnel->parms.iph;

	if (iph->daddr) {
		struct rtable *rt;
		struct flowi4 fl4;
		memset(&fl4, 0, sizeof(fl4));
		flowi4_init_output(&fl4, tunnel->parms.link,
				   be32_to_cpu(tunnel->parms.i_key),
				   RT_TOS(iph->tos), RT_SCOPE_UNIVERSE,
				   IPPROTO_IPIP, 0,
				   iph->daddr, iph->saddr, 0, 0);
		rt = ip_route_output_key(dev_net(dev), &fl4);
		if (!IS_ERR(rt)) {
			tdev = rt->dst.dev;
			ip_rt_put(rt);
		}
		dev->flags |= IFF_POINTOPOINT;
	}

	if (!tdev && tunnel->parms.link)
		tdev = __dev_get_by_index(dev_net(dev), tunnel->parms.link);

	if (tdev) {
		dev->hard_header_len = tdev->hard_header_len +
				       sizeof(struct iphdr);
		dev->mtu = tdev->mtu;
	}
	dev->iflink = tunnel->parms.link;
	return dev->mtu;
}

static int
vti_tunnel_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
{
	int err = 0;
	struct ip_tunnel_parm p;
	struct ip_tunnel *t;
	struct net *net = dev_net(dev);
	struct vti_net *ipn = net_generic(net, vti_net_id);

	switch (cmd) {
	case SIOCGETTUNNEL:
		t = NULL;
		if (dev == ipn->fb_tunnel_dev) {
			if (copy_from_user(&p, ifr->ifr_ifru.ifru_data,
					   sizeof(p))) {
				err = -EFAULT;
				break;
			}
			t = vti_tunnel_locate(net, &p, 0);
		}
		if (t == NULL)
			t = netdev_priv(dev);
		memcpy(&p, &t->parms, sizeof(p));
		p.i_flags |= GRE_KEY | VTI_ISVTI;
		p.o_flags |= GRE_KEY;
		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.iph.version != 4 || p.iph.protocol != IPPROTO_IPIP ||
		    p.iph.ihl != 5)
			goto done;

		t = vti_tunnel_locate(net, &p, cmd == SIOCADDTUNNEL);

		if (dev != ipn->fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
			if (t != NULL) {
				if (t->dev != dev) {
					err = -EEXIST;
					break;
				}
			} else {
				if (((dev->flags&IFF_POINTOPOINT) &&
				    !p.iph.daddr) ||
				    (!(dev->flags&IFF_POINTOPOINT) &&
				    p.iph.daddr)) {
					err = -EINVAL;
					break;
				}
				t = netdev_priv(dev);
				vti_tunnel_unlink(ipn, t);
				synchronize_net();
				t->parms.iph.saddr = p.iph.saddr;
				t->parms.iph.daddr = p.iph.daddr;
				t->parms.i_key = p.i_key;
				t->parms.o_key = p.o_key;
				t->parms.iph.protocol = IPPROTO_IPIP;
				memcpy(dev->dev_addr, &p.iph.saddr, 4);
				memcpy(dev->broadcast, &p.iph.daddr, 4);
				vti_tunnel_link(ipn, t);
				netdev_state_change(dev);
			}
		}

		if (t) {
			err = 0;
			if (cmd == SIOCCHGTUNNEL) {
				t->parms.i_key = p.i_key;
				t->parms.o_key = p.o_key;
				if (t->parms.link != p.link) {
					t->parms.link = p.link;
					vti_tunnel_bind_dev(dev);
					netdev_state_change(dev);
				}
			}
			p.i_flags |= GRE_KEY | VTI_ISVTI;
			p.o_flags |= GRE_KEY;
			if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms,
					 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 == ipn->fb_tunnel_dev) {
			err = -EFAULT;
			if (copy_from_user(&p, ifr->ifr_ifru.ifru_data,
					   sizeof(p)))
				goto done;
			err = -ENOENT;

			t = vti_tunnel_locate(net, &p, 0);
			if (t == NULL)
				goto done;
			err = -EPERM;
			if (t->dev == ipn->fb_tunnel_dev)
				goto done;
			dev = t->dev;
		}
		unregister_netdevice(dev);
		err = 0;
		break;

	default:
		err = -EINVAL;
	}

done:
	return err;
}

static int vti_tunnel_change_mtu(struct net_device *dev, int new_mtu)
{
	if (new_mtu < 68 || new_mtu > 0xFFF8)
		return -EINVAL;
	dev->mtu = new_mtu;
	return 0;
}

static const struct net_device_ops vti_netdev_ops = {
	.ndo_init	= vti_tunnel_init,
	.ndo_uninit	= vti_tunnel_uninit,
	.ndo_start_xmit	= vti_tunnel_xmit,
	.ndo_do_ioctl	= vti_tunnel_ioctl,
	.ndo_change_mtu	= vti_tunnel_change_mtu,
	.ndo_get_stats64 = ip_tunnel_get_stats64,
};

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

static void vti_tunnel_setup(struct net_device *dev)
{
	dev->netdev_ops		= &vti_netdev_ops;
	dev->destructor		= vti_dev_free;

	dev->type		= ARPHRD_TUNNEL;
	dev->hard_header_len	= LL_MAX_HEADER + sizeof(struct iphdr);
	dev->mtu		= ETH_DATA_LEN;
	dev->flags		= IFF_NOARP;
	dev->iflink		= 0;
	dev->addr_len		= 4;
	dev->features		|= NETIF_F_NETNS_LOCAL;
	dev->features		|= NETIF_F_LLTX;
	dev->priv_flags		&= ~IFF_XMIT_DST_RELEASE;
}

static int vti_tunnel_init(struct net_device *dev)
{
	struct ip_tunnel *tunnel = netdev_priv(dev);

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

	memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
	memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);

	dev->tstats = alloc_percpu(struct pcpu_tstats);
	if (!dev->tstats)
		return -ENOMEM;

	return 0;
}

static int __net_init vti_fb_tunnel_init(struct net_device *dev)
{
	struct ip_tunnel *tunnel = netdev_priv(dev);
	struct iphdr *iph = &tunnel->parms.iph;
	struct vti_net *ipn = net_generic(dev_net(dev), vti_net_id);

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

	iph->version		= 4;
	iph->protocol		= IPPROTO_IPIP;
	iph->ihl		= 5;

	dev->tstats = alloc_percpu(struct pcpu_tstats);
	if (!dev->tstats)
		return -ENOMEM;

	dev_hold(dev);
	rcu_assign_pointer(ipn->tunnels_wc[0], tunnel);
	return 0;
}

static struct xfrm_tunnel vti_handler __read_mostly = {
	.handler	=	vti_rcv,
	.err_handler	=	vti_err,
	.priority	=	1,
};

static void vti_destroy_tunnels(struct vti_net *ipn, struct list_head *head)
{
	int prio;

	for (prio = 1; prio < 4; prio++) {
		int h;
		for (h = 0; h < HASH_SIZE; h++) {
			struct ip_tunnel *t;

			t = rtnl_dereference(ipn->tunnels[prio][h]);
			while (t != NULL) {
				unregister_netdevice_queue(t->dev, head);
				t = rtnl_dereference(t->next);
			}
		}
	}
}

static int __net_init vti_init_net(struct net *net)
{
	int err;
	struct vti_net *ipn = net_generic(net, vti_net_id);

	ipn->tunnels[0] = ipn->tunnels_wc;
	ipn->tunnels[1] = ipn->tunnels_l;
	ipn->tunnels[2] = ipn->tunnels_r;
	ipn->tunnels[3] = ipn->tunnels_r_l;

	ipn->fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel),
					  "ip_vti0",
					  vti_tunnel_setup);
	if (!ipn->fb_tunnel_dev) {
		err = -ENOMEM;
		goto err_alloc_dev;
	}
	dev_net_set(ipn->fb_tunnel_dev, net);

	err = vti_fb_tunnel_init(ipn->fb_tunnel_dev);
	if (err)
		goto err_reg_dev;
	ipn->fb_tunnel_dev->rtnl_link_ops = &vti_link_ops;

	err = register_netdev(ipn->fb_tunnel_dev);
	if (err)
		goto err_reg_dev;
	return 0;

err_reg_dev:
	vti_dev_free(ipn->fb_tunnel_dev);
err_alloc_dev:
	/* nothing */
	return err;
}

static void __net_exit vti_exit_net(struct net *net)
{
	struct vti_net *ipn = net_generic(net, vti_net_id);
	LIST_HEAD(list);

	rtnl_lock();
	vti_destroy_tunnels(ipn, &list);
	unregister_netdevice_many(&list);
	rtnl_unlock();
}

static struct pernet_operations vti_net_ops = {
	.init = vti_init_net,
	.exit = vti_exit_net,
	.id   = &vti_net_id,
	.size = sizeof(struct vti_net),
};

static int vti_tunnel_validate(struct nlattr *tb[], struct nlattr *data[])
{
	return 0;
}

static void vti_netlink_parms(struct nlattr *data[],
			      struct ip_tunnel_parm *parms)
{
	memset(parms, 0, sizeof(*parms));

	parms->iph.protocol = IPPROTO_IPIP;

	if (!data)
		return;

	if (data[IFLA_VTI_LINK])
		parms->link = nla_get_u32(data[IFLA_VTI_LINK]);

	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_LOCAL])
		parms->iph.saddr = nla_get_be32(data[IFLA_VTI_LOCAL]);

	if (data[IFLA_VTI_REMOTE])
		parms->iph.daddr = nla_get_be32(data[IFLA_VTI_REMOTE]);

}

static int vti_newlink(struct net *src_net, struct net_device *dev,
		       struct nlattr *tb[], struct nlattr *data[])
{
	struct ip_tunnel *nt;
	struct net *net = dev_net(dev);
	struct vti_net *ipn = net_generic(net, vti_net_id);
	int mtu;
	int err;

	nt = netdev_priv(dev);
	vti_netlink_parms(data, &nt->parms);

	if (vti_tunnel_locate(net, &nt->parms, 0))
		return -EEXIST;

	mtu = vti_tunnel_bind_dev(dev);
	if (!tb[IFLA_MTU])
		dev->mtu = mtu;

	err = register_netdevice(dev);
	if (err)
		goto out;

	dev_hold(dev);
	vti_tunnel_link(ipn, nt);

out:
	return err;
}

static int vti_changelink(struct net_device *dev, struct nlattr *tb[],
			  struct nlattr *data[])
{
	struct ip_tunnel *t, *nt;
	struct net *net = dev_net(dev);
	struct vti_net *ipn = net_generic(net, vti_net_id);
	struct ip_tunnel_parm p;
	int mtu;

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

	nt = netdev_priv(dev);
	vti_netlink_parms(data, &p);

	t = vti_tunnel_locate(net, &p, 0);

	if (t) {
		if (t->dev != dev)
			return -EEXIST;
	} else {
		t = nt;

		vti_tunnel_unlink(ipn, t);
		t->parms.iph.saddr = p.iph.saddr;
		t->parms.iph.daddr = p.iph.daddr;
		t->parms.i_key = p.i_key;
		t->parms.o_key = p.o_key;
		if (dev->type != ARPHRD_ETHER) {
			memcpy(dev->dev_addr, &p.iph.saddr, 4);
			memcpy(dev->broadcast, &p.iph.daddr, 4);
		}
		vti_tunnel_link(ipn, t);
		netdev_state_change(dev);
	}

	if (t->parms.link != p.link) {
		t->parms.link = p.link;
		mtu = vti_tunnel_bind_dev(dev);
		if (!tb[IFLA_MTU])
			dev->mtu = mtu;
		netdev_state_change(dev);
	}

	return 0;
}

static size_t vti_get_size(const struct net_device *dev)
{
	return
		/* IFLA_VTI_LINK */
		nla_total_size(4) +
		/* IFLA_VTI_IKEY */
		nla_total_size(4) +
		/* IFLA_VTI_OKEY */
		nla_total_size(4) +
		/* IFLA_VTI_LOCAL */
		nla_total_size(4) +
		/* IFLA_VTI_REMOTE */
		nla_total_size(4) +
		0;
}

static int vti_fill_info(struct sk_buff *skb, const struct net_device *dev)
{
	struct ip_tunnel *t = netdev_priv(dev);
	struct ip_tunnel_parm *p = &t->parms;

	nla_put_u32(skb, IFLA_VTI_LINK, p->link);
	nla_put_be32(skb, IFLA_VTI_IKEY, p->i_key);
	nla_put_be32(skb, IFLA_VTI_OKEY, p->o_key);
	nla_put_be32(skb, IFLA_VTI_LOCAL, p->iph.saddr);
	nla_put_be32(skb, IFLA_VTI_REMOTE, p->iph.daddr);

	return 0;
}

static const struct nla_policy vti_policy[IFLA_VTI_MAX + 1] = {
	[IFLA_VTI_LINK]		= { .type = NLA_U32 },
	[IFLA_VTI_IKEY]		= { .type = NLA_U32 },
	[IFLA_VTI_OKEY]		= { .type = NLA_U32 },
	[IFLA_VTI_LOCAL]	= { .len = FIELD_SIZEOF(struct iphdr, saddr) },
	[IFLA_VTI_REMOTE]	= { .len = FIELD_SIZEOF(struct iphdr, daddr) },
};

static struct rtnl_link_ops vti_link_ops __read_mostly = {
	.kind		= "vti",
	.maxtype	= IFLA_VTI_MAX,
	.policy		= vti_policy,
	.priv_size	= sizeof(struct ip_tunnel),
	.setup		= vti_tunnel_setup,
	.validate	= vti_tunnel_validate,
	.newlink	= vti_newlink,
	.changelink	= vti_changelink,
	.get_size	= vti_get_size,
	.fill_info	= vti_fill_info,
};

static int __init vti_init(void)
{
	int err;

	pr_info("IPv4 over IPSec tunneling driver\n");

	err = register_pernet_device(&vti_net_ops);
	if (err < 0)
		return err;
	err = xfrm4_mode_tunnel_input_register(&vti_handler);
	if (err < 0) {
		unregister_pernet_device(&vti_net_ops);
		pr_info(KERN_INFO "vti init: can't register tunnel\n");
	}

	err = rtnl_link_register(&vti_link_ops);
	if (err < 0)
		goto rtnl_link_failed;

	return err;

rtnl_link_failed:
	xfrm4_mode_tunnel_input_deregister(&vti_handler);
	unregister_pernet_device(&vti_net_ops);
	return err;
}

static void __exit vti_fini(void)
{
	rtnl_link_unregister(&vti_link_ops);
	if (xfrm4_mode_tunnel_input_deregister(&vti_handler))
		pr_info("vti close: can't deregister tunnel\n");

	unregister_pernet_device(&vti_net_ops);
}

module_init(vti_init);
module_exit(vti_fini);
MODULE_LICENSE("GPL");
MODULE_ALIAS_RTNL_LINK("vti");
MODULE_ALIAS_NETDEV("ip_vti0");