net/ipv4: VTI support new module for ip_vti.

New VTI tunnel kernel module, Kconfig and Makefile changes.

Signed-off-by: Saurabh Mohan <[e-mail]>
Reviewed-by: Stephen Hemminger <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/linux/if_tunnel.h

···
 
 #define IFLA_GRE_MAX	(__IFLA_GRE_MAX - 1)
 
+/* VTI-mode i_flags */
+#define VTI_ISVTI 0x0001
+
+enum {
+	IFLA_VTI_UNSPEC,
+	IFLA_VTI_LINK,
+	IFLA_VTI_IKEY,
+	IFLA_VTI_OKEY,
+	IFLA_VTI_LOCAL,
+	IFLA_VTI_REMOTE,
+	__IFLA_VTI_MAX,
+};
+
+#define IFLA_VTI_MAX	(__IFLA_VTI_MAX - 1)
 #endif /* _IF_TUNNEL_H_ */

net/ipv4/Kconfig

···
 
 	  If unsure, say N.
 
+config NET_IPVTI
+	tristate "Virtual (secure) IP: tunneling"
+	select INET_TUNNEL
+	depends on INET_XFRM_MODE_TUNNEL
+	---help---
+	  Tunneling means encapsulating data of one protocol type within
+	  another protocol and sending it over a channel that understands the
+	  encapsulating protocol. This can be used with xfrm mode tunnel to give
+	  the notion of a secure tunnel for IPSEC and then use routing protocol
+	  on top.
+
 config INET_AH
 	tristate "IP: AH transformation"
 	select XFRM_ALGO

net/ipv4/Makefile

···
 obj-$(CONFIG_NET_IPIP) += ipip.o
 obj-$(CONFIG_NET_IPGRE_DEMUX) += gre.o
 obj-$(CONFIG_NET_IPGRE) += ip_gre.o
+obj-$(CONFIG_NET_IPVTI) += ip_vti.o
 obj-$(CONFIG_SYN_COOKIES) += syncookies.o
 obj-$(CONFIG_INET_AH) += ah4.o
 obj-$(CONFIG_INET_ESP) += esp4.o

net/ipv4/ip_vti.c

···
+/*
+ *	Linux NET3: IP/IP protocol decoder modified to support
+ *		    virtual tunnel interface
+ *
+ *	Authors:
+ *		Saurabh Mohan ([e-mail]) 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/ipip.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 **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);
+
+/* Locking : hash tables are protected by RCU and RTNL */
+
+#define for_each_ip_tunnel_rcu(start) \
+	for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))
+
+/* often modified stats are per cpu, other are shared (netdev->stats) */
+struct pcpu_tstats {
+	u64	rx_packets;
+	u64	rx_bytes;
+	u64	tx_packets;
+	u64	tx_bytes;
+	struct	u64_stats_sync	syncp;
+};
+
+#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 rtnl_link_stats64 *vti_get_stats64(struct net_device *dev,
+						 struct rtnl_link_stats64 *tot)
+{
+	int i;
+
+	for_each_possible_cpu(i) {
+		const struct pcpu_tstats *tstats = per_cpu_ptr(dev->tstats, i);
+		u64 rx_packets, rx_bytes, tx_packets, tx_bytes;
+		unsigned int start;
+
+		do {
+			start = u64_stats_fetch_begin_bh(&tstats->syncp);
+			rx_packets = tstats->rx_packets;
+			tx_packets = tstats->tx_packets;
+			rx_bytes = tstats->rx_bytes;
+			tx_bytes = tstats->tx_bytes;
+		} while (u64_stats_fetch_retry_bh(&tstats->syncp, start));
+
+		tot->rx_packets += rx_packets;
+		tot->tx_packets += tx_packets;
+		tot->rx_bytes   += rx_bytes;
+		tot->tx_bytes   += tx_bytes;
+	}
+
+	tot->multicast = dev->stats.multicast;
+	tot->rx_crc_errors = dev->stats.rx_crc_errors;
+	tot->rx_fifo_errors = dev->stats.rx_fifo_errors;
+	tot->rx_length_errors = dev->stats.rx_length_errors;
+	tot->rx_errors = dev->stats.rx_errors;
+	tot->tx_fifo_errors = dev->stats.tx_fifo_errors;
+	tot->tx_carrier_errors = dev->stats.tx_carrier_errors;
+	tot->tx_dropped = dev->stats.tx_dropped;
+	tot->tx_aborted_errors = dev->stats.tx_aborted_errors;
+	tot->tx_errors = dev->stats.tx_errors;
+
+	return tot;
+}
+
+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(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(ipn->tunnels_r[h0])
+		if (remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
+			return t;
+
+	for_each_ip_tunnel_rcu(ipn->tunnels_l[h1])
+		if (local == t->parms.iph.saddr && (t->dev->flags&IFF_UP))
+			return t;
+
+	for_each_ip_tunnel_rcu(ipn->tunnels_wc[0])
+		if (t && (t->dev->flags&IFF_UP))
+			return t;
+	return NULL;
+}
+
+static struct ip_tunnel **__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 **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;
+
+	rcu_read_lock();
+	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:
+	rcu_read_unlock();
+	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);
+
+	rcu_read_lock();
+	tunnel = vti_tunnel_lookup(dev_net(skb->dev), iph->saddr, iph->daddr);
+	if (tunnel != NULL) {
+		struct pcpu_tstats *tstats;
+
+		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->dev = tunnel->dev;
+		rcu_read_unlock();
+		return 1;
+	}
+	rcu_read_unlock();
+
+	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,
+			   htonl(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;
+	}
+
+	IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
+			      IPSKB_REROUTED);
+	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,
+				   htonl(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 (!capable(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 (!capable(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 = vti_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");