Initial import

1 files changed, 2363 insertions, 0 deletions

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
new file mode 100644
index 000000000..e470ae59d
--- /dev/null
+++ b/drivers/net/tun.c
@@ -0,0 +1,2363 @@
+/*
+ *  TUN - Universal TUN/TAP device driver.
+ *  Copyright (C) 1999-2002 Maxim Krasnyansky <maxk@qualcomm.com>
+ *
+ *  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 program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ *  GNU General Public License for more details.
+ *
+ *  $Id: tun.c,v 1.15 2002/03/01 02:44:24 maxk Exp $
+ */
+
+/*
+ *  Changes:
+ *
+ *  Mike Kershaw <dragorn@kismetwireless.net> 2005/08/14
+ *    Add TUNSETLINK ioctl to set the link encapsulation
+ *
+ *  Mark Smith <markzzzsmith@yahoo.com.au>
+ *    Use eth_random_addr() for tap MAC address.
+ *
+ *  Harald Roelle <harald.roelle@ifi.lmu.de>  2004/04/20
+ *    Fixes in packet dropping, queue length setting and queue wakeup.
+ *    Increased default tx queue length.
+ *    Added ethtool API.
+ *    Minor cleanups
+ *
+ *  Daniel Podlejski <underley@underley.eu.org>
+ *    Modifications for 2.3.99-pre5 kernel.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#define DRV_NAME	"tun"
+#define DRV_VERSION	"1.6"
+#define DRV_DESCRIPTION	"Universal TUN/TAP device driver"
+#define DRV_COPYRIGHT	"(C) 1999-2004 Max Krasnyansky <maxk@qualcomm.com>"
+
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/major.h>
+#include <linux/slab.h>
+#include <linux/poll.h>
+#include <linux/fcntl.h>
+#include <linux/init.h>
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/miscdevice.h>
+#include <linux/ethtool.h>
+#include <linux/rtnetlink.h>
+#include <linux/compat.h>
+#include <linux/if.h>
+#include <linux/if_arp.h>
+#include <linux/if_ether.h>
+#include <linux/if_tun.h>
+#include <linux/if_vlan.h>
+#include <linux/crc32.h>
+#include <linux/nsproxy.h>
+#include <linux/virtio_net.h>
+#include <linux/rcupdate.h>
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
+#include <net/rtnetlink.h>
+#include <net/sock.h>
+#include <linux/seq_file.h>
+#include <linux/uio.h>
+
+#include <asm/uaccess.h>
+
+/* Uncomment to enable debugging */
+/* #define TUN_DEBUG 1 */
+
+#ifdef TUN_DEBUG
+static int debug;
+
+#define tun_debug(level, tun, fmt, args...)			\
+do {								\
+	if (tun->debug)						\
+		netdev_printk(level, tun->dev, fmt, ##args);	\
+} while (0)
+#define DBG1(level, fmt, args...)				\
+do {								\
+	if (debug == 2)						\
+		printk(level fmt, ##args);			\
+} while (0)
+#else
+#define tun_debug(level, tun, fmt, args...)			\
+do {								\
+	if (0)							\
+		netdev_printk(level, tun->dev, fmt, ##args);	\
+} while (0)
+#define DBG1(level, fmt, args...)				\
+do {								\
+	if (0)							\
+		printk(level fmt, ##args);			\
+} while (0)
+#endif
+
+/* TUN device flags */
+
+/* IFF_ATTACH_QUEUE is never stored in device flags,
+ * overload it to mean fasync when stored there.
+ */
+#define TUN_FASYNC	IFF_ATTACH_QUEUE
+/* High bits in flags field are unused. */
+#define TUN_VNET_LE     0x80000000
+
+#define TUN_FEATURES (IFF_NO_PI | IFF_ONE_QUEUE | IFF_VNET_HDR | \
+		      IFF_MULTI_QUEUE)
+#define GOODCOPY_LEN 128
+
+#define FLT_EXACT_COUNT 8
+struct tap_filter {
+	unsigned int    count;    /* Number of addrs. Zero means disabled */
+	u32             mask[2];  /* Mask of the hashed addrs */
+	unsigned char	addr[FLT_EXACT_COUNT][ETH_ALEN];
+};
+
+/* MAX_TAP_QUEUES 256 is chosen to allow rx/tx queues to be equal
+ * to max number of VCPUs in guest. */
+#define MAX_TAP_QUEUES 256
+#define MAX_TAP_FLOWS  4096
+
+#define TUN_FLOW_EXPIRE (3 * HZ)
+
+/* A tun_file connects an open character device to a tuntap netdevice. It
+ * also contains all socket related structures (except sock_fprog and tap_filter)
+ * to serve as one transmit queue for tuntap device. The sock_fprog and
+ * tap_filter were kept in tun_struct since they were used for filtering for the
+ * netdevice not for a specific queue (at least I didn't see the requirement for
+ * this).
+ *
+ * RCU usage:
+ * The tun_file and tun_struct are loosely coupled, the pointer from one to the
+ * other can only be read while rcu_read_lock or rtnl_lock is held.
+ */
+struct tun_file {
+	struct sock sk;
+	struct socket socket;
+	struct socket_wq wq;
+	struct tun_struct __rcu *tun;
+	struct net *net;
+	struct fasync_struct *fasync;
+	/* only used for fasnyc */
+	unsigned int flags;
+	union {
+		u16 queue_index;
+		unsigned int ifindex;
+	};
+	struct list_head next;
+	struct tun_struct *detached;
+};
+
+struct tun_flow_entry {
+	struct hlist_node hash_link;
+	struct rcu_head rcu;
+	struct tun_struct *tun;
+
+	u32 rxhash;
+	u32 rps_rxhash;
+	int queue_index;
+	unsigned long updated;
+};
+
+#define TUN_NUM_FLOW_ENTRIES 1024
+
+/* Since the socket were moved to tun_file, to preserve the behavior of persist
+ * device, socket filter, sndbuf and vnet header size were restore when the
+ * file were attached to a persist device.
+ */
+struct tun_struct {
+	struct tun_file __rcu	*tfiles[MAX_TAP_QUEUES];
+	unsigned int            numqueues;
+	unsigned int 		flags;
+	kuid_t			owner;
+	kgid_t			group;
+
+	struct net_device	*dev;
+	netdev_features_t	set_features;
+#define TUN_USER_FEATURES (NETIF_F_HW_CSUM|NETIF_F_TSO_ECN|NETIF_F_TSO| \
+			  NETIF_F_TSO6|NETIF_F_UFO)
+
+	int			vnet_hdr_sz;
+	int			sndbuf;
+	struct tap_filter	txflt;
+	struct sock_fprog	fprog;
+	/* protected by rtnl lock */
+	bool			filter_attached;
+#ifdef TUN_DEBUG
+	int debug;
+#endif
+	spinlock_t lock;
+	struct hlist_head flows[TUN_NUM_FLOW_ENTRIES];
+	struct timer_list flow_gc_timer;
+	unsigned long ageing_time;
+	unsigned int numdisabled;
+	struct list_head disabled;
+	void *security;
+	u32 flow_count;
+};
+
+static inline u16 tun16_to_cpu(struct tun_struct *tun, __virtio16 val)
+{
+	return __virtio16_to_cpu(tun->flags & TUN_VNET_LE, val);
+}
+
+static inline __virtio16 cpu_to_tun16(struct tun_struct *tun, u16 val)
+{
+	return __cpu_to_virtio16(tun->flags & TUN_VNET_LE, val);
+}
+
+static inline u32 tun_hashfn(u32 rxhash)
+{
+	return rxhash & 0x3ff;
+}
+
+static struct tun_flow_entry *tun_flow_find(struct hlist_head *head, u32 rxhash)
+{
+	struct tun_flow_entry *e;
+
+	hlist_for_each_entry_rcu(e, head, hash_link) {
+		if (e->rxhash == rxhash)
+			return e;
+	}
+	return NULL;
+}
+
+static struct tun_flow_entry *tun_flow_create(struct tun_struct *tun,
+					      struct hlist_head *head,
+					      u32 rxhash, u16 queue_index)
+{
+	struct tun_flow_entry *e = kmalloc(sizeof(*e), GFP_ATOMIC);
+
+	if (e) {
+		tun_debug(KERN_INFO, tun, "create flow: hash %u index %u\n",
+			  rxhash, queue_index);
+		e->updated = jiffies;
+		e->rxhash = rxhash;
+		e->rps_rxhash = 0;
+		e->queue_index = queue_index;
+		e->tun = tun;
+		hlist_add_head_rcu(&e->hash_link, head);
+		++tun->flow_count;
+	}
+	return e;
+}
+
+static void tun_flow_delete(struct tun_struct *tun, struct tun_flow_entry *e)
+{
+	tun_debug(KERN_INFO, tun, "delete flow: hash %u index %u\n",
+		  e->rxhash, e->queue_index);
+	hlist_del_rcu(&e->hash_link);
+	kfree_rcu(e, rcu);
+	--tun->flow_count;
+}
+
+static void tun_flow_flush(struct tun_struct *tun)
+{
+	int i;
+
+	spin_lock_bh(&tun->lock);
+	for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) {
+		struct tun_flow_entry *e;
+		struct hlist_node *n;
+
+		hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link)
+			tun_flow_delete(tun, e);
+	}
+	spin_unlock_bh(&tun->lock);
+}
+
+static void tun_flow_delete_by_queue(struct tun_struct *tun, u16 queue_index)
+{
+	int i;
+
+	spin_lock_bh(&tun->lock);
+	for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) {
+		struct tun_flow_entry *e;
+		struct hlist_node *n;
+
+		hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link) {
+			if (e->queue_index == queue_index)
+				tun_flow_delete(tun, e);
+		}
+	}
+	spin_unlock_bh(&tun->lock);
+}
+
+static void tun_flow_cleanup(unsigned long data)
+{
+	struct tun_struct *tun = (struct tun_struct *)data;
+	unsigned long delay = tun->ageing_time;
+	unsigned long next_timer = jiffies + delay;
+	unsigned long count = 0;
+	int i;
+
+	tun_debug(KERN_INFO, tun, "tun_flow_cleanup\n");
+
+	spin_lock_bh(&tun->lock);
+	for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) {
+		struct tun_flow_entry *e;
+		struct hlist_node *n;
+
+		hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link) {
+			unsigned long this_timer;
+			count++;
+			this_timer = e->updated + delay;
+			if (time_before_eq(this_timer, jiffies))
+				tun_flow_delete(tun, e);
+			else if (time_before(this_timer, next_timer))
+				next_timer = this_timer;
+		}
+	}
+
+	if (count)
+		mod_timer(&tun->flow_gc_timer, round_jiffies_up(next_timer));
+	spin_unlock_bh(&tun->lock);
+}
+
+static void tun_flow_update(struct tun_struct *tun, u32 rxhash,
+			    struct tun_file *tfile)
+{
+	struct hlist_head *head;
+	struct tun_flow_entry *e;
+	unsigned long delay = tun->ageing_time;
+	u16 queue_index = tfile->queue_index;
+
+	if (!rxhash)
+		return;
+	else
+		head = &tun->flows[tun_hashfn(rxhash)];
+
+	rcu_read_lock();
+
+	/* We may get a very small possibility of OOO during switching, not
+	 * worth to optimize.*/
+	if (tun->numqueues == 1 || tfile->detached)
+		goto unlock;
+
+	e = tun_flow_find(head, rxhash);
+	if (likely(e)) {
+		/* TODO: keep queueing to old queue until it's empty? */
+		e->queue_index = queue_index;
+		e->updated = jiffies;
+		sock_rps_record_flow_hash(e->rps_rxhash);
+	} else {
+		spin_lock_bh(&tun->lock);
+		if (!tun_flow_find(head, rxhash) &&
+		    tun->flow_count < MAX_TAP_FLOWS)
+			tun_flow_create(tun, head, rxhash, queue_index);
+
+		if (!timer_pending(&tun->flow_gc_timer))
+			mod_timer(&tun->flow_gc_timer,
+				  round_jiffies_up(jiffies + delay));
+		spin_unlock_bh(&tun->lock);
+	}
+
+unlock:
+	rcu_read_unlock();
+}
+
+/**
+ * Save the hash received in the stack receive path and update the
+ * flow_hash table accordingly.
+ */
+static inline void tun_flow_save_rps_rxhash(struct tun_flow_entry *e, u32 hash)
+{
+	if (unlikely(e->rps_rxhash != hash))
+		e->rps_rxhash = hash;
+}
+
+/* We try to identify a flow through its rxhash first. The reason that
+ * we do not check rxq no. is because some cards(e.g 82599), chooses
+ * the rxq based on the txq where the last packet of the flow comes. As
+ * the userspace application move between processors, we may get a
+ * different rxq no. here. If we could not get rxhash, then we would
+ * hope the rxq no. may help here.
+ */
+static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb,
+			    void *accel_priv, select_queue_fallback_t fallback)
+{
+	struct tun_struct *tun = netdev_priv(dev);
+	struct tun_flow_entry *e;
+	u32 txq = 0;
+	u32 numqueues = 0;
+
+	rcu_read_lock();
+	numqueues = ACCESS_ONCE(tun->numqueues);
+
+	txq = skb_get_hash(skb);
+	if (txq) {
+		e = tun_flow_find(&tun->flows[tun_hashfn(txq)], txq);
+		if (e) {
+			tun_flow_save_rps_rxhash(e, txq);
+			txq = e->queue_index;
+		} else
+			/* use multiply and shift instead of expensive divide */
+			txq = ((u64)txq * numqueues) >> 32;
+	} else if (likely(skb_rx_queue_recorded(skb))) {
+		txq = skb_get_rx_queue(skb);
+		while (unlikely(txq >= numqueues))
+			txq -= numqueues;
+	}
+
+	rcu_read_unlock();
+	return txq;
+}
+
+static inline bool tun_not_capable(struct tun_struct *tun)
+{
+	const struct cred *cred = current_cred();
+	struct net *net = dev_net(tun->dev);
+
+	return ((uid_valid(tun->owner) && !uid_eq(cred->euid, tun->owner)) ||
+		  (gid_valid(tun->group) && !in_egroup_p(tun->group))) &&
+		!ns_capable(net->user_ns, CAP_NET_ADMIN);
+}
+
+static void tun_set_real_num_queues(struct tun_struct *tun)
+{
+	netif_set_real_num_tx_queues(tun->dev, tun->numqueues);
+	netif_set_real_num_rx_queues(tun->dev, tun->numqueues);
+}
+
+static void tun_disable_queue(struct tun_struct *tun, struct tun_file *tfile)
+{
+	tfile->detached = tun;
+	list_add_tail(&tfile->next, &tun->disabled);
+	++tun->numdisabled;
+}
+
+static struct tun_struct *tun_enable_queue(struct tun_file *tfile)
+{
+	struct tun_struct *tun = tfile->detached;
+
+	tfile->detached = NULL;
+	list_del_init(&tfile->next);
+	--tun->numdisabled;
+	return tun;
+}
+
+static void tun_queue_purge(struct tun_file *tfile)
+{
+	skb_queue_purge(&tfile->sk.sk_receive_queue);
+	skb_queue_purge(&tfile->sk.sk_error_queue);
+}
+
+static void __tun_detach(struct tun_file *tfile, bool clean)
+{
+	struct tun_file *ntfile;
+	struct tun_struct *tun;
+
+	tun = rtnl_dereference(tfile->tun);
+
+	if (tun && !tfile->detached) {
+		u16 index = tfile->queue_index;
+		BUG_ON(index >= tun->numqueues);
+
+		rcu_assign_pointer(tun->tfiles[index],
+				   tun->tfiles[tun->numqueues - 1]);
+		ntfile = rtnl_dereference(tun->tfiles[index]);
+		ntfile->queue_index = index;
+
+		--tun->numqueues;
+		if (clean) {
+			RCU_INIT_POINTER(tfile->tun, NULL);
+			sock_put(&tfile->sk);
+		} else
+			tun_disable_queue(tun, tfile);
+
+		synchronize_net();
+		tun_flow_delete_by_queue(tun, tun->numqueues + 1);
+		/* Drop read queue */
+		tun_queue_purge(tfile);
+		tun_set_real_num_queues(tun);
+	} else if (tfile->detached && clean) {
+		tun = tun_enable_queue(tfile);
+		sock_put(&tfile->sk);
+	}
+
+	if (clean) {
+		if (tun && tun->numqueues == 0 && tun->numdisabled == 0) {
+			netif_carrier_off(tun->dev);
+
+			if (!(tun->flags & IFF_PERSIST) &&
+			    tun->dev->reg_state == NETREG_REGISTERED)
+				unregister_netdevice(tun->dev);
+		}
+
+		BUG_ON(!test_bit(SOCK_EXTERNALLY_ALLOCATED,
+				 &tfile->socket.flags));
+		sk_release_kernel(&tfile->sk);
+	}
+}
+
+static void tun_detach(struct tun_file *tfile, bool clean)
+{
+	rtnl_lock();
+	__tun_detach(tfile, clean);
+	rtnl_unlock();
+}
+
+static void tun_detach_all(struct net_device *dev)
+{
+	struct tun_struct *tun = netdev_priv(dev);
+	struct tun_file *tfile, *tmp;
+	int i, n = tun->numqueues;
+
+	for (i = 0; i < n; i++) {
+		tfile = rtnl_dereference(tun->tfiles[i]);
+		BUG_ON(!tfile);
+		tfile->socket.sk->sk_data_ready(tfile->socket.sk);
+		RCU_INIT_POINTER(tfile->tun, NULL);
+		--tun->numqueues;
+	}
+	list_for_each_entry(tfile, &tun->disabled, next) {
+		tfile->socket.sk->sk_data_ready(tfile->socket.sk);
+		RCU_INIT_POINTER(tfile->tun, NULL);
+	}
+	BUG_ON(tun->numqueues != 0);
+
+	synchronize_net();
+	for (i = 0; i < n; i++) {
+		tfile = rtnl_dereference(tun->tfiles[i]);
+		/* Drop read queue */
+		tun_queue_purge(tfile);
+		sock_put(&tfile->sk);
+	}
+	list_for_each_entry_safe(tfile, tmp, &tun->disabled, next) {
+		tun_enable_queue(tfile);
+		tun_queue_purge(tfile);
+		sock_put(&tfile->sk);
+	}
+	BUG_ON(tun->numdisabled != 0);
+
+	if (tun->flags & IFF_PERSIST)
+		module_put(THIS_MODULE);
+}
+
+static int tun_attach(struct tun_struct *tun, struct file *file, bool skip_filter)
+{
+	struct tun_file *tfile = file->private_data;
+	int err;
+
+	err = security_tun_dev_attach(tfile->socket.sk, tun->security);
+	if (err < 0)
+		goto out;
+
+	err = -EINVAL;
+	if (rtnl_dereference(tfile->tun) && !tfile->detached)
+		goto out;
+
+	err = -EBUSY;
+	if (!(tun->flags & IFF_MULTI_QUEUE) && tun->numqueues == 1)
+		goto out;
+
+	err = -E2BIG;
+	if (!tfile->detached &&
+	    tun->numqueues + tun->numdisabled == MAX_TAP_QUEUES)
+		goto out;
+
+	err = 0;
+
+	/* Re-attach the filter to persist device */
+	if (!skip_filter && (tun->filter_attached == true)) {
+		err = sk_attach_filter(&tun->fprog, tfile->socket.sk);
+		if (!err)
+			goto out;
+	}
+	tfile->queue_index = tun->numqueues;
+	rcu_assign_pointer(tfile->tun, tun);
+	rcu_assign_pointer(tun->tfiles[tun->numqueues], tfile);
+	tun->numqueues++;
+
+	if (tfile->detached)
+		tun_enable_queue(tfile);
+	else
+		sock_hold(&tfile->sk);
+
+	tun_set_real_num_queues(tun);
+
+	/* device is allowed to go away first, so no need to hold extra
+	 * refcnt.
+	 */
+
+out:
+	return err;
+}
+
+static struct tun_struct *__tun_get(struct tun_file *tfile)
+{
+	struct tun_struct *tun;
+
+	rcu_read_lock();
+	tun = rcu_dereference(tfile->tun);
+	if (tun)
+		dev_hold(tun->dev);
+	rcu_read_unlock();
+
+	return tun;
+}
+
+static struct tun_struct *tun_get(struct file *file)
+{
+	return __tun_get(file->private_data);
+}
+
+static void tun_put(struct tun_struct *tun)
+{
+	dev_put(tun->dev);
+}
+
+/* TAP filtering */
+static void addr_hash_set(u32 *mask, const u8 *addr)
+{
+	int n = ether_crc(ETH_ALEN, addr) >> 26;
+	mask[n >> 5] |= (1 << (n & 31));
+}
+
+static unsigned int addr_hash_test(const u32 *mask, const u8 *addr)
+{
+	int n = ether_crc(ETH_ALEN, addr) >> 26;
+	return mask[n >> 5] & (1 << (n & 31));
+}
+
+static int update_filter(struct tap_filter *filter, void __user *arg)
+{
+	struct { u8 u[ETH_ALEN]; } *addr;
+	struct tun_filter uf;
+	int err, alen, n, nexact;
+
+	if (copy_from_user(&uf, arg, sizeof(uf)))
+		return -EFAULT;
+
+	if (!uf.count) {
+		/* Disabled */
+		filter->count = 0;
+		return 0;
+	}
+
+	alen = ETH_ALEN * uf.count;
+	addr = kmalloc(alen, GFP_KERNEL);
+	if (!addr)
+		return -ENOMEM;
+
+	if (copy_from_user(addr, arg + sizeof(uf), alen)) {
+		err = -EFAULT;
+		goto done;
+	}
+
+	/* The filter is updated without holding any locks. Which is
+	 * perfectly safe. We disable it first and in the worst
+	 * case we'll accept a few undesired packets. */
+	filter->count = 0;
+	wmb();
+
+	/* Use first set of addresses as an exact filter */
+	for (n = 0; n < uf.count && n < FLT_EXACT_COUNT; n++)
+		memcpy(filter->addr[n], addr[n].u, ETH_ALEN);
+
+	nexact = n;
+
+	/* Remaining multicast addresses are hashed,
+	 * unicast will leave the filter disabled. */
+	memset(filter->mask, 0, sizeof(filter->mask));
+	for (; n < uf.count; n++) {
+		if (!is_multicast_ether_addr(addr[n].u)) {
+			err = 0; /* no filter */
+			goto done;
+		}
+		addr_hash_set(filter->mask, addr[n].u);
+	}
+
+	/* For ALLMULTI just set the mask to all ones.
+	 * This overrides the mask populated above. */
+	if ((uf.flags & TUN_FLT_ALLMULTI))
+		memset(filter->mask, ~0, sizeof(filter->mask));
+
+	/* Now enable the filter */
+	wmb();
+	filter->count = nexact;
+
+	/* Return the number of exact filters */
+	err = nexact;
+
+done:
+	kfree(addr);
+	return err;
+}
+
+/* Returns: 0 - drop, !=0 - accept */
+static int run_filter(struct tap_filter *filter, const struct sk_buff *skb)
+{
+	/* Cannot use eth_hdr(skb) here because skb_mac_hdr() is incorrect
+	 * at this point. */
+	struct ethhdr *eh = (struct ethhdr *) skb->data;
+	int i;
+
+	/* Exact match */
+	for (i = 0; i < filter->count; i++)
+		if (ether_addr_equal(eh->h_dest, filter->addr[i]))
+			return 1;
+
+	/* Inexact match (multicast only) */
+	if (is_multicast_ether_addr(eh->h_dest))
+		return addr_hash_test(filter->mask, eh->h_dest);
+
+	return 0;
+}
+
+/*
+ * Checks whether the packet is accepted or not.
+ * Returns: 0 - drop, !=0 - accept
+ */
+static int check_filter(struct tap_filter *filter, const struct sk_buff *skb)
+{
+	if (!filter->count)
+		return 1;
+
+	return run_filter(filter, skb);
+}
+
+/* Network device part of the driver */
+
+static const struct ethtool_ops tun_ethtool_ops;
+
+/* Net device detach from fd. */
+static void tun_net_uninit(struct net_device *dev)
+{
+	tun_detach_all(dev);
+}
+
+/* Net device open. */
+static int tun_net_open(struct net_device *dev)
+{
+	netif_tx_start_all_queues(dev);
+	return 0;
+}
+
+/* Net device close. */
+static int tun_net_close(struct net_device *dev)
+{
+	netif_tx_stop_all_queues(dev);
+	return 0;
+}
+
+/* Net device start xmit */
+static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct tun_struct *tun = netdev_priv(dev);
+	int txq = skb->queue_mapping;
+	struct tun_file *tfile;
+	u32 numqueues = 0;
+
+	rcu_read_lock();
+	tfile = rcu_dereference(tun->tfiles[txq]);
+	numqueues = ACCESS_ONCE(tun->numqueues);
+
+	/* Drop packet if interface is not attached */
+	if (txq >= numqueues)
+		goto drop;
+
+	if (numqueues == 1) {
+		/* Select queue was not called for the skbuff, so we extract the
+		 * RPS hash and save it into the flow_table here.
+		 */
+		__u32 rxhash;
+
+		rxhash = skb_get_hash(skb);
+		if (rxhash) {
+			struct tun_flow_entry *e;
+			e = tun_flow_find(&tun->flows[tun_hashfn(rxhash)],
+					rxhash);
+			if (e)
+				tun_flow_save_rps_rxhash(e, rxhash);
+		}
+	}
+
+	tun_debug(KERN_INFO, tun, "tun_net_xmit %d\n", skb->len);
+
+	BUG_ON(!tfile);
+
+	/* Drop if the filter does not like it.
+	 * This is a noop if the filter is disabled.
+	 * Filter can be enabled only for the TAP devices. */
+	if (!check_filter(&tun->txflt, skb))
+		goto drop;
+
+	if (tfile->socket.sk->sk_filter &&
+	    sk_filter(tfile->socket.sk, skb))
+		goto drop;
+
+	/* Limit the number of packets queued by dividing txq length with the
+	 * number of queues.
+	 */
+	if (skb_queue_len(&tfile->socket.sk->sk_receive_queue) * numqueues
+			  >= dev->tx_queue_len)
+		goto drop;
+
+	if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC)))
+		goto drop;
+
+	if (skb->sk) {
+		sock_tx_timestamp(skb->sk, &skb_shinfo(skb)->tx_flags);
+		sw_tx_timestamp(skb);
+	}
+
+	/* Orphan the skb - required as we might hang on to it
+	 * for indefinite time.
+	 */
+	skb_orphan(skb);
+
+	nf_reset(skb);
+
+	/* Enqueue packet */
+	skb_queue_tail(&tfile->socket.sk->sk_receive_queue, skb);
+
+	/* Notify and wake up reader process */
+	if (tfile->flags & TUN_FASYNC)
+		kill_fasync(&tfile->fasync, SIGIO, POLL_IN);
+	tfile->socket.sk->sk_data_ready(tfile->socket.sk);
+
+	rcu_read_unlock();
+	return NETDEV_TX_OK;
+
+drop:
+	dev->stats.tx_dropped++;
+	skb_tx_error(skb);
+	kfree_skb(skb);
+	rcu_read_unlock();
+	return NET_XMIT_DROP;
+}
+
+static void tun_net_mclist(struct net_device *dev)
+{
+	/*
+	 * This callback is supposed to deal with mc filter in
+	 * _rx_ path and has nothing to do with the _tx_ path.
+	 * In rx path we always accept everything userspace gives us.
+	 */
+}
+
+#define MIN_MTU 68
+#define MAX_MTU 65535
+
+static int
+tun_net_change_mtu(struct net_device *dev, int new_mtu)
+{
+	if (new_mtu < MIN_MTU || new_mtu + dev->hard_header_len > MAX_MTU)
+		return -EINVAL;
+	dev->mtu = new_mtu;
+	return 0;
+}
+
+static netdev_features_t tun_net_fix_features(struct net_device *dev,
+	netdev_features_t features)
+{
+	struct tun_struct *tun = netdev_priv(dev);
+
+	return (features & tun->set_features) | (features & ~TUN_USER_FEATURES);
+}
+#ifdef CONFIG_NET_POLL_CONTROLLER
+static void tun_poll_controller(struct net_device *dev)
+{
+	/*
+	 * Tun only receives frames when:
+	 * 1) the char device endpoint gets data from user space
+	 * 2) the tun socket gets a sendmsg call from user space
+	 * Since both of those are synchronous operations, we are guaranteed
+	 * never to have pending data when we poll for it
+	 * so there is nothing to do here but return.
+	 * We need this though so netpoll recognizes us as an interface that
+	 * supports polling, which enables bridge devices in virt setups to
+	 * still use netconsole
+	 */
+	return;
+}
+#endif
+static const struct net_device_ops tun_netdev_ops = {
+	.ndo_uninit		= tun_net_uninit,
+	.ndo_open		= tun_net_open,
+	.ndo_stop		= tun_net_close,
+	.ndo_start_xmit		= tun_net_xmit,
+	.ndo_change_mtu		= tun_net_change_mtu,
+	.ndo_fix_features	= tun_net_fix_features,
+	.ndo_select_queue	= tun_select_queue,
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	.ndo_poll_controller	= tun_poll_controller,
+#endif
+};
+
+static const struct net_device_ops tap_netdev_ops = {
+	.ndo_uninit		= tun_net_uninit,
+	.ndo_open		= tun_net_open,
+	.ndo_stop		= tun_net_close,
+	.ndo_start_xmit		= tun_net_xmit,
+	.ndo_change_mtu		= tun_net_change_mtu,
+	.ndo_fix_features	= tun_net_fix_features,
+	.ndo_set_rx_mode	= tun_net_mclist,
+	.ndo_set_mac_address	= eth_mac_addr,
+	.ndo_validate_addr	= eth_validate_addr,
+	.ndo_select_queue	= tun_select_queue,
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	.ndo_poll_controller	= tun_poll_controller,
+#endif
+};
+
+static void tun_flow_init(struct tun_struct *tun)
+{
+	int i;
+
+	for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++)
+		INIT_HLIST_HEAD(&tun->flows[i]);
+
+	tun->ageing_time = TUN_FLOW_EXPIRE;
+	setup_timer(&tun->flow_gc_timer, tun_flow_cleanup, (unsigned long)tun);
+	mod_timer(&tun->flow_gc_timer,
+		  round_jiffies_up(jiffies + tun->ageing_time));
+}
+
+static void tun_flow_uninit(struct tun_struct *tun)
+{
+	del_timer_sync(&tun->flow_gc_timer);
+	tun_flow_flush(tun);
+}
+
+/* Initialize net device. */
+static void tun_net_init(struct net_device *dev)
+{
+	struct tun_struct *tun = netdev_priv(dev);
+
+	switch (tun->flags & TUN_TYPE_MASK) {
+	case IFF_TUN:
+		dev->netdev_ops = &tun_netdev_ops;
+
+		/* Point-to-Point TUN Device */
+		dev->hard_header_len = 0;
+		dev->addr_len = 0;
+		dev->mtu = 1500;
+
+		/* Zero header length */
+		dev->type = ARPHRD_NONE;
+		dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
+		dev->tx_queue_len = TUN_READQ_SIZE;  /* We prefer our own queue length */
+		break;
+
+	case IFF_TAP:
+		dev->netdev_ops = &tap_netdev_ops;
+		/* Ethernet TAP Device */
+		ether_setup(dev);
+		dev->priv_flags &= ~IFF_TX_SKB_SHARING;
+		dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
+
+		eth_hw_addr_random(dev);
+
+		dev->tx_queue_len = TUN_READQ_SIZE;  /* We prefer our own queue length */
+		break;
+	}
+}
+
+/* Character device part */
+
+/* Poll */
+static unsigned int tun_chr_poll(struct file *file, poll_table *wait)
+{
+	struct tun_file *tfile = file->private_data;
+	struct tun_struct *tun = __tun_get(tfile);
+	struct sock *sk;
+	unsigned int mask = 0;
+
+	if (!tun)
+		return POLLERR;
+
+	sk = tfile->socket.sk;
+
+	tun_debug(KERN_INFO, tun, "tun_chr_poll\n");
+
+	poll_wait(file, sk_sleep(sk), wait);
+
+	if (!skb_queue_empty(&sk->sk_receive_queue))
+		mask |= POLLIN | POLLRDNORM;
+
+	if (sock_writeable(sk) ||
+	    (!test_and_set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags) &&
+	     sock_writeable(sk)))
+		mask |= POLLOUT | POLLWRNORM;
+
+	if (tun->dev->reg_state != NETREG_REGISTERED)
+		mask = POLLERR;
+
+	tun_put(tun);
+	return mask;
+}
+
+/* prepad is the amount to reserve at front.  len is length after that.
+ * linear is a hint as to how much to copy (usually headers). */
+static struct sk_buff *tun_alloc_skb(struct tun_file *tfile,
+				     size_t prepad, size_t len,
+				     size_t linear, int noblock)
+{
+	struct sock *sk = tfile->socket.sk;
+	struct sk_buff *skb;
+	int err;
+
+	/* Under a page?  Don't bother with paged skb. */
+	if (prepad + len < PAGE_SIZE || !linear)
+		linear = len;
+
+	skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
+				   &err, 0);
+	if (!skb)
+		return ERR_PTR(err);
+
+	skb_reserve(skb, prepad);
+	skb_put(skb, linear);
+	skb->data_len = len - linear;
+	skb->len += len - linear;
+
+	return skb;
+}
+
+/* Get packet from user space buffer */
+static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
+			    void *msg_control, struct iov_iter *from,
+			    int noblock)
+{
+	struct tun_pi pi = { 0, cpu_to_be16(ETH_P_IP) };
+	struct sk_buff *skb;
+	size_t total_len = iov_iter_count(from);
+	size_t len = total_len, align = NET_SKB_PAD, linear;
+	struct virtio_net_hdr gso = { 0 };
+	int good_linear;
+	int copylen;
+	bool zerocopy = false;
+	int err;
+	u32 rxhash;
+	ssize_t n;
+
+	if (!(tun->flags & IFF_NO_PI)) {
+		if (len < sizeof(pi))
+			return -EINVAL;
+		len -= sizeof(pi);
+
+		n = copy_from_iter(&pi, sizeof(pi), from);
+		if (n != sizeof(pi))
+			return -EFAULT;
+	}
+
+	if (tun->flags & IFF_VNET_HDR) {
+		if (len < tun->vnet_hdr_sz)
+			return -EINVAL;
+		len -= tun->vnet_hdr_sz;
+
+		n = copy_from_iter(&gso, sizeof(gso), from);
+		if (n != sizeof(gso))
+			return -EFAULT;
+
+		if ((gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
+		    tun16_to_cpu(tun, gso.csum_start) + tun16_to_cpu(tun, gso.csum_offset) + 2 > tun16_to_cpu(tun, gso.hdr_len))
+			gso.hdr_len = cpu_to_tun16(tun, tun16_to_cpu(tun, gso.csum_start) + tun16_to_cpu(tun, gso.csum_offset) + 2);
+
+		if (tun16_to_cpu(tun, gso.hdr_len) > len)
+			return -EINVAL;
+		iov_iter_advance(from, tun->vnet_hdr_sz - sizeof(gso));
+	}
+
+	if ((tun->flags & TUN_TYPE_MASK) == IFF_TAP) {
+		align += NET_IP_ALIGN;
+		if (unlikely(len < ETH_HLEN ||
+			     (gso.hdr_len && tun16_to_cpu(tun, gso.hdr_len) < ETH_HLEN)))
+			return -EINVAL;
+	}
+
+	good_linear = SKB_MAX_HEAD(align);
+
+	if (msg_control) {
+		struct iov_iter i = *from;
+
+		/* There are 256 bytes to be copied in skb, so there is
+		 * enough room for skb expand head in case it is used.
+		 * The rest of the buffer is mapped from userspace.
+		 */
+		copylen = gso.hdr_len ? tun16_to_cpu(tun, gso.hdr_len) : GOODCOPY_LEN;
+		if (copylen > good_linear)
+			copylen = good_linear;
+		linear = copylen;
+		iov_iter_advance(&i, copylen);
+		if (iov_iter_npages(&i, INT_MAX) <= MAX_SKB_FRAGS)
+			zerocopy = true;
+	}
+
+	if (!zerocopy) {
+		copylen = len;
+		if (tun16_to_cpu(tun, gso.hdr_len) > good_linear)
+			linear = good_linear;
+		else
+			linear = tun16_to_cpu(tun, gso.hdr_len);
+	}
+
+	skb = tun_alloc_skb(tfile, align, copylen, linear, noblock);
+	if (IS_ERR(skb)) {
+		if (PTR_ERR(skb) != -EAGAIN)
+			tun->dev->stats.rx_dropped++;
+		return PTR_ERR(skb);
+	}
+
+	if (zerocopy)
+		err = zerocopy_sg_from_iter(skb, from);
+	else {
+		err = skb_copy_datagram_from_iter(skb, 0, from, len);
+		if (!err && msg_control) {
+			struct ubuf_info *uarg = msg_control;
+			uarg->callback(uarg, false);
+		}
+	}
+
+	if (err) {
+		tun->dev->stats.rx_dropped++;
+		kfree_skb(skb);
+		return -EFAULT;
+	}
+
+	if (gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
+		if (!skb_partial_csum_set(skb, tun16_to_cpu(tun, gso.csum_start),
+					  tun16_to_cpu(tun, gso.csum_offset))) {
+			tun->dev->stats.rx_frame_errors++;
+			kfree_skb(skb);
+			return -EINVAL;
+		}
+	}
+
+	switch (tun->flags & TUN_TYPE_MASK) {
+	case IFF_TUN:
+		if (tun->flags & IFF_NO_PI) {
+			switch (skb->data[0] & 0xf0) {
+			case 0x40:
+				pi.proto = htons(ETH_P_IP);
+				break;
+			case 0x60:
+				pi.proto = htons(ETH_P_IPV6);
+				break;
+			default:
+				tun->dev->stats.rx_dropped++;
+				kfree_skb(skb);
+				return -EINVAL;
+			}
+		}
+
+		skb_reset_mac_header(skb);
+		skb->protocol = pi.proto;
+		skb->dev = tun->dev;
+		break;
+	case IFF_TAP:
+		skb->protocol = eth_type_trans(skb, tun->dev);
+		break;
+	}
+
+	if (gso.gso_type != VIRTIO_NET_HDR_GSO_NONE) {
+		pr_debug("GSO!\n");
+		switch (gso.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
+		case VIRTIO_NET_HDR_GSO_TCPV4:
+			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
+			break;
+		case VIRTIO_NET_HDR_GSO_TCPV6:
+			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
+			break;
+		case VIRTIO_NET_HDR_GSO_UDP:
+			skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
+			break;
+		default:
+			tun->dev->stats.rx_frame_errors++;
+			kfree_skb(skb);
+			return -EINVAL;
+		}
+
+		if (gso.gso_type & VIRTIO_NET_HDR_GSO_ECN)
+			skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
+
+		skb_shinfo(skb)->gso_size = tun16_to_cpu(tun, gso.gso_size);
+		if (skb_shinfo(skb)->gso_size == 0) {
+			tun->dev->stats.rx_frame_errors++;
+			kfree_skb(skb);
+			return -EINVAL;
+		}
+
+		/* Header must be checked, and gso_segs computed. */
+		skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
+		skb_shinfo(skb)->gso_segs = 0;
+	}
+
+	/* copy skb_ubuf_info for callback when skb has no error */
+	if (zerocopy) {
+		skb_shinfo(skb)->destructor_arg = msg_control;
+		skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
+		skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
+	}
+
+	skb_reset_network_header(skb);
+	skb_probe_transport_header(skb, 0);
+
+	rxhash = skb_get_hash(skb);
+	netif_rx_ni(skb);
+
+	tun->dev->stats.rx_packets++;
+	tun->dev->stats.rx_bytes += len;
+
+	tun_flow_update(tun, rxhash, tfile);
+	return total_len;
+}
+
+static ssize_t tun_chr_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct tun_struct *tun = tun_get(file);
+	struct tun_file *tfile = file->private_data;
+	ssize_t result;
+
+	if (!tun)
+		return -EBADFD;
+
+	result = tun_get_user(tun, tfile, NULL, from, file->f_flags & O_NONBLOCK);
+
+	tun_put(tun);
+	return result;
+}
+
+/* Put packet to the user space buffer */
+static ssize_t tun_put_user(struct tun_struct *tun,
+			    struct tun_file *tfile,
+			    struct sk_buff *skb,
+			    struct iov_iter *iter)
+{
+	struct tun_pi pi = { 0, skb->protocol };
+	ssize_t total;
+	int vlan_offset = 0;
+	int vlan_hlen = 0;
+	int vnet_hdr_sz = 0;
+
+	if (skb_vlan_tag_present(skb))
+		vlan_hlen = VLAN_HLEN;
+
+	if (tun->flags & IFF_VNET_HDR)
+		vnet_hdr_sz = tun->vnet_hdr_sz;
+
+	total = skb->len + vlan_hlen + vnet_hdr_sz;
+
+	if (!(tun->flags & IFF_NO_PI)) {
+		if (iov_iter_count(iter) < sizeof(pi))
+			return -EINVAL;
+
+		total += sizeof(pi);
+		if (iov_iter_count(iter) < total) {
+			/* Packet will be striped */
+			pi.flags |= TUN_PKT_STRIP;
+		}
+
+		if (copy_to_iter(&pi, sizeof(pi), iter) != sizeof(pi))
+			return -EFAULT;
+	}
+
+	if (vnet_hdr_sz) {
+		struct virtio_net_hdr gso = { 0 }; /* no info leak */
+		if (iov_iter_count(iter) < vnet_hdr_sz)
+			return -EINVAL;
+
+		if (skb_is_gso(skb)) {
+			struct skb_shared_info *sinfo = skb_shinfo(skb);
+
+			/* This is a hint as to how much should be linear. */
+			gso.hdr_len = cpu_to_tun16(tun, skb_headlen(skb));
+			gso.gso_size = cpu_to_tun16(tun, sinfo->gso_size);
+			if (sinfo->gso_type & SKB_GSO_TCPV4)
+				gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
+			else if (sinfo->gso_type & SKB_GSO_TCPV6)
+				gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
+			else if (sinfo->gso_type & SKB_GSO_UDP)
+				gso.gso_type = VIRTIO_NET_HDR_GSO_UDP;
+			else {
+				pr_err("unexpected GSO type: "
+				       "0x%x, gso_size %d, hdr_len %d\n",
+				       sinfo->gso_type, tun16_to_cpu(tun, gso.gso_size),
+				       tun16_to_cpu(tun, gso.hdr_len));
+				print_hex_dump(KERN_ERR, "tun: ",
+					       DUMP_PREFIX_NONE,
+					       16, 1, skb->head,
+					       min((int)tun16_to_cpu(tun, gso.hdr_len), 64), true);
+				WARN_ON_ONCE(1);
+				return -EINVAL;
+			}
+			if (sinfo->gso_type & SKB_GSO_TCP_ECN)
+				gso.gso_type |= VIRTIO_NET_HDR_GSO_ECN;
+		} else
+			gso.gso_type = VIRTIO_NET_HDR_GSO_NONE;
+
+		if (skb->ip_summed == CHECKSUM_PARTIAL) {
+			gso.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
+			gso.csum_start = cpu_to_tun16(tun, skb_checksum_start_offset(skb) +
+						      vlan_hlen);
+			gso.csum_offset = cpu_to_tun16(tun, skb->csum_offset);
+		} else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
+			gso.flags = VIRTIO_NET_HDR_F_DATA_VALID;
+		} /* else everything is zero */
+
+		if (copy_to_iter(&gso, sizeof(gso), iter) != sizeof(gso))
+			return -EFAULT;
+
+		iov_iter_advance(iter, vnet_hdr_sz - sizeof(gso));
+	}
+
+	if (vlan_hlen) {
+		int ret;
+		struct {
+			__be16 h_vlan_proto;
+			__be16 h_vlan_TCI;
+		} veth;
+
+		veth.h_vlan_proto = skb->vlan_proto;
+		veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
+
+		vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
+
+		ret = skb_copy_datagram_iter(skb, 0, iter, vlan_offset);
+		if (ret || !iov_iter_count(iter))
+			goto done;
+
+		ret = copy_to_iter(&veth, sizeof(veth), iter);
+		if (ret != sizeof(veth) || !iov_iter_count(iter))
+			goto done;
+	}
+
+	skb_copy_datagram_iter(skb, vlan_offset, iter, skb->len - vlan_offset);
+
+done:
+	tun->dev->stats.tx_packets++;
+	tun->dev->stats.tx_bytes += skb->len + vlan_hlen;
+
+	return total;
+}
+
+static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
+			   struct iov_iter *to,
+			   int noblock)
+{
+	struct sk_buff *skb;
+	ssize_t ret;
+	int peeked, err, off = 0;
+
+	tun_debug(KERN_INFO, tun, "tun_do_read\n");
+
+	if (!iov_iter_count(to))
+		return 0;
+
+	if (tun->dev->reg_state != NETREG_REGISTERED)
+		return -EIO;
+
+	/* Read frames from queue */
+	skb = __skb_recv_datagram(tfile->socket.sk, noblock ? MSG_DONTWAIT : 0,
+				  &peeked, &off, &err);
+	if (!skb)
+		return err;
+
+	ret = tun_put_user(tun, tfile, skb, to);
+	if (unlikely(ret < 0))
+		kfree_skb(skb);
+	else
+		consume_skb(skb);
+
+	return ret;
+}
+
+static ssize_t tun_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct file *file = iocb->ki_filp;
+	struct tun_file *tfile = file->private_data;
+	struct tun_struct *tun = __tun_get(tfile);
+	ssize_t len = iov_iter_count(to), ret;
+
+	if (!tun)
+		return -EBADFD;
+	ret = tun_do_read(tun, tfile, to, file->f_flags & O_NONBLOCK);
+	ret = min_t(ssize_t, ret, len);
+	if (ret > 0)
+		iocb->ki_pos = ret;
+	tun_put(tun);
+	return ret;
+}
+
+static void tun_free_netdev(struct net_device *dev)
+{
+	struct tun_struct *tun = netdev_priv(dev);
+
+	BUG_ON(!(list_empty(&tun->disabled)));
+	tun_flow_uninit(tun);
+	security_tun_dev_free_security(tun->security);
+	free_netdev(dev);
+}
+
+static void tun_setup(struct net_device *dev)
+{
+	struct tun_struct *tun = netdev_priv(dev);
+
+	tun->owner = INVALID_UID;
+	tun->group = INVALID_GID;
+
+	dev->ethtool_ops = &tun_ethtool_ops;
+	dev->destructor = tun_free_netdev;
+}
+
+/* Trivial set of netlink ops to allow deleting tun or tap
+ * device with netlink.
+ */
+static int tun_validate(struct nlattr *tb[], struct nlattr *data[])
+{
+	return -EINVAL;
+}
+
+static struct rtnl_link_ops tun_link_ops __read_mostly = {
+	.kind		= DRV_NAME,
+	.priv_size	= sizeof(struct tun_struct),
+	.setup		= tun_setup,
+	.validate	= tun_validate,
+};
+
+static void tun_sock_write_space(struct sock *sk)
+{
+	struct tun_file *tfile;
+	wait_queue_head_t *wqueue;
+
+	if (!sock_writeable(sk))
+		return;
+
+	if (!test_and_clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags))
+		return;
+
+	wqueue = sk_sleep(sk);
+	if (wqueue && waitqueue_active(wqueue))
+		wake_up_interruptible_sync_poll(wqueue, POLLOUT |
+						POLLWRNORM | POLLWRBAND);
+
+	tfile = container_of(sk, struct tun_file, sk);
+	kill_fasync(&tfile->fasync, SIGIO, POLL_OUT);
+}
+
+static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len)
+{
+	int ret;
+	struct tun_file *tfile = container_of(sock, struct tun_file, socket);
+	struct tun_struct *tun = __tun_get(tfile);
+
+	if (!tun)
+		return -EBADFD;
+
+	ret = tun_get_user(tun, tfile, m->msg_control, &m->msg_iter,
+			   m->msg_flags & MSG_DONTWAIT);
+	tun_put(tun);
+	return ret;
+}
+
+static int tun_recvmsg(struct socket *sock, struct msghdr *m, size_t total_len,
+		       int flags)
+{
+	struct tun_file *tfile = container_of(sock, struct tun_file, socket);
+	struct tun_struct *tun = __tun_get(tfile);
+	int ret;
+
+	if (!tun)
+		return -EBADFD;
+
+	if (flags & ~(MSG_DONTWAIT|MSG_TRUNC|MSG_ERRQUEUE)) {
+		ret = -EINVAL;
+		goto out;
+	}
+	if (flags & MSG_ERRQUEUE) {
+		ret = sock_recv_errqueue(sock->sk, m, total_len,
+					 SOL_PACKET, TUN_TX_TIMESTAMP);
+		goto out;
+	}
+	ret = tun_do_read(tun, tfile, &m->msg_iter, flags & MSG_DONTWAIT);
+	if (ret > (ssize_t)total_len) {
+		m->msg_flags |= MSG_TRUNC;
+		ret = flags & MSG_TRUNC ? ret : total_len;
+	}
+out:
+	tun_put(tun);
+	return ret;
+}
+
+static int tun_release(struct socket *sock)
+{
+	if (sock->sk)
+		sock_put(sock->sk);
+	return 0;
+}
+
+/* Ops structure to mimic raw sockets with tun */
+static const struct proto_ops tun_socket_ops = {
+	.sendmsg = tun_sendmsg,
+	.recvmsg = tun_recvmsg,
+	.release = tun_release,
+};
+
+static struct proto tun_proto = {
+	.name		= "tun",
+	.owner		= THIS_MODULE,
+	.obj_size	= sizeof(struct tun_file),
+};
+
+static int tun_flags(struct tun_struct *tun)
+{
+	return tun->flags & (TUN_FEATURES | IFF_PERSIST | IFF_TUN | IFF_TAP);
+}
+
+static ssize_t tun_show_flags(struct device *dev, struct device_attribute *attr,
+			      char *buf)
+{
+	struct tun_struct *tun = netdev_priv(to_net_dev(dev));
+	return sprintf(buf, "0x%x\n", tun_flags(tun));
+}
+
+static ssize_t tun_show_owner(struct device *dev, struct device_attribute *attr,
+			      char *buf)
+{
+	struct tun_struct *tun = netdev_priv(to_net_dev(dev));
+	return uid_valid(tun->owner)?
+		sprintf(buf, "%u\n",
+			from_kuid_munged(current_user_ns(), tun->owner)):
+		sprintf(buf, "-1\n");
+}
+
+static ssize_t tun_show_group(struct device *dev, struct device_attribute *attr,
+			      char *buf)
+{
+	struct tun_struct *tun = netdev_priv(to_net_dev(dev));
+	return gid_valid(tun->group) ?
+		sprintf(buf, "%u\n",
+			from_kgid_munged(current_user_ns(), tun->group)):
+		sprintf(buf, "-1\n");
+}
+
+static DEVICE_ATTR(tun_flags, 0444, tun_show_flags, NULL);
+static DEVICE_ATTR(owner, 0444, tun_show_owner, NULL);
+static DEVICE_ATTR(group, 0444, tun_show_group, NULL);
+
+static struct attribute *tun_dev_attrs[] = {
+	&dev_attr_tun_flags.attr,
+	&dev_attr_owner.attr,
+	&dev_attr_group.attr,
+	NULL
+};
+
+static const struct attribute_group tun_attr_group = {
+	.attrs = tun_dev_attrs
+};
+
+static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
+{
+	struct tun_struct *tun;
+	struct tun_file *tfile = file->private_data;
+	struct net_device *dev;
+	int err;
+
+	if (tfile->detached)
+		return -EINVAL;
+
+	dev = __dev_get_by_name(net, ifr->ifr_name);
+	if (dev) {
+		if (ifr->ifr_flags & IFF_TUN_EXCL)
+			return -EBUSY;
+		if ((ifr->ifr_flags & IFF_TUN) && dev->netdev_ops == &tun_netdev_ops)
+			tun = netdev_priv(dev);
+		else if ((ifr->ifr_flags & IFF_TAP) && dev->netdev_ops == &tap_netdev_ops)
+			tun = netdev_priv(dev);
+		else
+			return -EINVAL;
+
+		if (!!(ifr->ifr_flags & IFF_MULTI_QUEUE) !=
+		    !!(tun->flags & IFF_MULTI_QUEUE))
+			return -EINVAL;
+
+		if (tun_not_capable(tun))
+			return -EPERM;
+		err = security_tun_dev_open(tun->security);
+		if (err < 0)
+			return err;
+
+		err = tun_attach(tun, file, ifr->ifr_flags & IFF_NOFILTER);
+		if (err < 0)
+			return err;
+
+		if (tun->flags & IFF_MULTI_QUEUE &&
+		    (tun->numqueues + tun->numdisabled > 1)) {
+			/* One or more queue has already been attached, no need
+			 * to initialize the device again.
+			 */
+			return 0;
+		}
+	}
+	else {
+		char *name;
+		unsigned long flags = 0;
+		int queues = ifr->ifr_flags & IFF_MULTI_QUEUE ?
+			     MAX_TAP_QUEUES : 1;
+
+		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
+			return -EPERM;
+		err = security_tun_dev_create();
+		if (err < 0)
+			return err;
+
+		/* Set dev type */
+		if (ifr->ifr_flags & IFF_TUN) {
+			/* TUN device */
+			flags |= IFF_TUN;
+			name = "tun%d";
+		} else if (ifr->ifr_flags & IFF_TAP) {
+			/* TAP device */
+			flags |= IFF_TAP;
+			name = "tap%d";
+		} else
+			return -EINVAL;
+
+		if (*ifr->ifr_name)
+			name = ifr->ifr_name;
+
+		dev = alloc_netdev_mqs(sizeof(struct tun_struct), name,
+				       NET_NAME_UNKNOWN, tun_setup, queues,
+				       queues);
+
+		if (!dev)
+			return -ENOMEM;
+
+		dev_net_set(dev, net);
+		dev->rtnl_link_ops = &tun_link_ops;
+		dev->ifindex = tfile->ifindex;
+		dev->sysfs_groups[0] = &tun_attr_group;
+
+		tun = netdev_priv(dev);
+		tun->dev = dev;
+		tun->flags = flags;
+		tun->txflt.count = 0;
+		tun->vnet_hdr_sz = sizeof(struct virtio_net_hdr);
+
+		tun->filter_attached = false;
+		tun->sndbuf = tfile->socket.sk->sk_sndbuf;
+
+		spin_lock_init(&tun->lock);
+
+		err = security_tun_dev_alloc_security(&tun->security);
+		if (err < 0)
+			goto err_free_dev;
+
+		tun_net_init(dev);
+		tun_flow_init(tun);
+
+		dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST |
+				   TUN_USER_FEATURES | NETIF_F_HW_VLAN_CTAG_TX |
+				   NETIF_F_HW_VLAN_STAG_TX;
+		dev->features = dev->hw_features;
+		dev->vlan_features = dev->features &
+				     ~(NETIF_F_HW_VLAN_CTAG_TX |
+				       NETIF_F_HW_VLAN_STAG_TX);
+
+		INIT_LIST_HEAD(&tun->disabled);
+		err = tun_attach(tun, file, false);
+		if (err < 0)
+			goto err_free_flow;
+
+		err = register_netdevice(tun->dev);
+		if (err < 0)
+			goto err_detach;
+	}
+
+	netif_carrier_on(tun->dev);
+
+	tun_debug(KERN_INFO, tun, "tun_set_iff\n");
+
+	tun->flags = (tun->flags & ~TUN_FEATURES) |
+		(ifr->ifr_flags & TUN_FEATURES);
+
+	/* Make sure persistent devices do not get stuck in
+	 * xoff state.
+	 */
+	if (netif_running(tun->dev))
+		netif_tx_wake_all_queues(tun->dev);
+
+	strcpy(ifr->ifr_name, tun->dev->name);
+	return 0;
+
+err_detach:
+	tun_detach_all(dev);
+err_free_flow:
+	tun_flow_uninit(tun);
+	security_tun_dev_free_security(tun->security);
+err_free_dev:
+	free_netdev(dev);
+	return err;
+}
+
+static void tun_get_iff(struct net *net, struct tun_struct *tun,
+		       struct ifreq *ifr)
+{
+	tun_debug(KERN_INFO, tun, "tun_get_iff\n");
+
+	strcpy(ifr->ifr_name, tun->dev->name);
+
+	ifr->ifr_flags = tun_flags(tun);
+
+}
+
+/* This is like a cut-down ethtool ops, except done via tun fd so no
+ * privs required. */
+static int set_offload(struct tun_struct *tun, unsigned long arg)
+{
+	netdev_features_t features = 0;
+
+	if (arg & TUN_F_CSUM) {
+		features |= NETIF_F_HW_CSUM;
+		arg &= ~TUN_F_CSUM;
+
+		if (arg & (TUN_F_TSO4|TUN_F_TSO6)) {
+			if (arg & TUN_F_TSO_ECN) {
+				features |= NETIF_F_TSO_ECN;
+				arg &= ~TUN_F_TSO_ECN;
+			}
+			if (arg & TUN_F_TSO4)
+				features |= NETIF_F_TSO;
+			if (arg & TUN_F_TSO6)
+				features |= NETIF_F_TSO6;
+			arg &= ~(TUN_F_TSO4|TUN_F_TSO6);
+		}
+
+		if (arg & TUN_F_UFO) {
+			features |= NETIF_F_UFO;
+			arg &= ~TUN_F_UFO;
+		}
+	}
+
+	/* This gives the user a way to test for new features in future by
+	 * trying to set them. */
+	if (arg)
+		return -EINVAL;
+
+	tun->set_features = features;
+	netdev_update_features(tun->dev);
+
+	return 0;
+}
+
+static void tun_detach_filter(struct tun_struct *tun, int n)
+{
+	int i;
+	struct tun_file *tfile;
+
+	for (i = 0; i < n; i++) {
+		tfile = rtnl_dereference(tun->tfiles[i]);
+		sk_detach_filter(tfile->socket.sk);
+	}
+
+	tun->filter_attached = false;
+}
+
+static int tun_attach_filter(struct tun_struct *tun)
+{
+	int i, ret = 0;
+	struct tun_file *tfile;
+
+	for (i = 0; i < tun->numqueues; i++) {
+		tfile = rtnl_dereference(tun->tfiles[i]);
+		ret = sk_attach_filter(&tun->fprog, tfile->socket.sk);
+		if (ret) {
+			tun_detach_filter(tun, i);
+			return ret;
+		}
+	}
+
+	tun->filter_attached = true;
+	return ret;
+}
+
+static void tun_set_sndbuf(struct tun_struct *tun)
+{
+	struct tun_file *tfile;
+	int i;
+
+	for (i = 0; i < tun->numqueues; i++) {
+		tfile = rtnl_dereference(tun->tfiles[i]);
+		tfile->socket.sk->sk_sndbuf = tun->sndbuf;
+	}
+}
+
+static int tun_set_queue(struct file *file, struct ifreq *ifr)
+{
+	struct tun_file *tfile = file->private_data;
+	struct tun_struct *tun;
+	int ret = 0;
+
+	rtnl_lock();
+
+	if (ifr->ifr_flags & IFF_ATTACH_QUEUE) {
+		tun = tfile->detached;
+		if (!tun) {
+			ret = -EINVAL;
+			goto unlock;
+		}
+		ret = security_tun_dev_attach_queue(tun->security);
+		if (ret < 0)
+			goto unlock;
+		ret = tun_attach(tun, file, false);
+	} else if (ifr->ifr_flags & IFF_DETACH_QUEUE) {
+		tun = rtnl_dereference(tfile->tun);
+		if (!tun || !(tun->flags & IFF_MULTI_QUEUE) || tfile->detached)
+			ret = -EINVAL;
+		else
+			__tun_detach(tfile, false);
+	} else
+		ret = -EINVAL;
+
+unlock:
+	rtnl_unlock();
+	return ret;
+}
+
+static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
+			    unsigned long arg, int ifreq_len)
+{
+	struct tun_file *tfile = file->private_data;
+	struct tun_struct *tun;
+	void __user* argp = (void __user*)arg;
+	struct ifreq ifr;
+	kuid_t owner;
+	kgid_t group;
+	int sndbuf;
+	int vnet_hdr_sz;
+	unsigned int ifindex;
+	int le;
+	int ret;
+
+	if (cmd == TUNSETIFF || cmd == TUNSETQUEUE || _IOC_TYPE(cmd) == 0x89) {
+		if (copy_from_user(&ifr, argp, ifreq_len))
+			return -EFAULT;
+	} else {
+		memset(&ifr, 0, sizeof(ifr));
+	}
+	if (cmd == TUNGETFEATURES) {
+		/* Currently this just means: "what IFF flags are valid?".
+		 * This is needed because we never checked for invalid flags on
+		 * TUNSETIFF.
+		 */
+		return put_user(IFF_TUN | IFF_TAP | TUN_FEATURES,
+				(unsigned int __user*)argp);
+	} else if (cmd == TUNSETQUEUE)
+		return tun_set_queue(file, &ifr);
+
+	ret = 0;
+	rtnl_lock();
+
+	tun = __tun_get(tfile);
+	if (cmd == TUNSETIFF && !tun) {
+		ifr.ifr_name[IFNAMSIZ-1] = '\0';
+
+		ret = tun_set_iff(tfile->net, file, &ifr);
+
+		if (ret)
+			goto unlock;
+
+		if (copy_to_user(argp, &ifr, ifreq_len))
+			ret = -EFAULT;
+		goto unlock;
+	}
+	if (cmd == TUNSETIFINDEX) {
+		ret = -EPERM;
+		if (tun)
+			goto unlock;
+
+		ret = -EFAULT;
+		if (copy_from_user(&ifindex, argp, sizeof(ifindex)))
+			goto unlock;
+
+		ret = 0;
+		tfile->ifindex = ifindex;
+		goto unlock;
+	}
+
+	ret = -EBADFD;
+	if (!tun)
+		goto unlock;
+
+	tun_debug(KERN_INFO, tun, "tun_chr_ioctl cmd %u\n", cmd);
+
+	ret = 0;
+	switch (cmd) {
+	case TUNGETIFF:
+		tun_get_iff(current->nsproxy->net_ns, tun, &ifr);
+
+		if (tfile->detached)
+			ifr.ifr_flags |= IFF_DETACH_QUEUE;
+		if (!tfile->socket.sk->sk_filter)
+			ifr.ifr_flags |= IFF_NOFILTER;
+
+		if (copy_to_user(argp, &ifr, ifreq_len))
+			ret = -EFAULT;
+		break;
+
+	case TUNSETNOCSUM:
+		/* Disable/Enable checksum */
+
+		/* [unimplemented] */
+		tun_debug(KERN_INFO, tun, "ignored: set checksum %s\n",
+			  arg ? "disabled" : "enabled");
+		break;
+
+	case TUNSETPERSIST:
+		/* Disable/Enable persist mode. Keep an extra reference to the
+		 * module to prevent the module being unprobed.
+		 */
+		if (arg && !(tun->flags & IFF_PERSIST)) {
+			tun->flags |= IFF_PERSIST;
+			__module_get(THIS_MODULE);
+		}
+		if (!arg && (tun->flags & IFF_PERSIST)) {
+			tun->flags &= ~IFF_PERSIST;
+			module_put(THIS_MODULE);
+		}
+
+		tun_debug(KERN_INFO, tun, "persist %s\n",
+			  arg ? "enabled" : "disabled");
+		break;
+
+	case TUNSETOWNER:
+		/* Set owner of the device */
+		owner = make_kuid(current_user_ns(), arg);
+		if (!uid_valid(owner)) {
+			ret = -EINVAL;
+			break;
+		}
+		tun->owner = owner;
+		tun_debug(KERN_INFO, tun, "owner set to %u\n",
+			  from_kuid(&init_user_ns, tun->owner));
+		break;
+
+	case TUNSETGROUP:
+		/* Set group of the device */
+		group = make_kgid(current_user_ns(), arg);
+		if (!gid_valid(group)) {
+			ret = -EINVAL;
+			break;
+		}
+		tun->group = group;
+		tun_debug(KERN_INFO, tun, "group set to %u\n",
+			  from_kgid(&init_user_ns, tun->group));
+		break;
+
+	case TUNSETLINK:
+		/* Only allow setting the type when the interface is down */
+		if (tun->dev->flags & IFF_UP) {
+			tun_debug(KERN_INFO, tun,
+				  "Linktype set failed because interface is up\n");
+			ret = -EBUSY;
+		} else {
+			tun->dev->type = (int) arg;
+			tun_debug(KERN_INFO, tun, "linktype set to %d\n",
+				  tun->dev->type);
+			ret = 0;
+		}
+		break;
+
+#ifdef TUN_DEBUG
+	case TUNSETDEBUG:
+		tun->debug = arg;
+		break;
+#endif
+	case TUNSETOFFLOAD:
+		ret = set_offload(tun, arg);
+		break;
+
+	case TUNSETTXFILTER:
+		/* Can be set only for TAPs */
+		ret = -EINVAL;
+		if ((tun->flags & TUN_TYPE_MASK) != IFF_TAP)
+			break;
+		ret = update_filter(&tun->txflt, (void __user *)arg);
+		break;
+
+	case SIOCGIFHWADDR:
+		/* Get hw address */
+		memcpy(ifr.ifr_hwaddr.sa_data, tun->dev->dev_addr, ETH_ALEN);
+		ifr.ifr_hwaddr.sa_family = tun->dev->type;
+		if (copy_to_user(argp, &ifr, ifreq_len))
+			ret = -EFAULT;
+		break;
+
+	case SIOCSIFHWADDR:
+		/* Set hw address */
+		tun_debug(KERN_DEBUG, tun, "set hw address: %pM\n",
+			  ifr.ifr_hwaddr.sa_data);
+
+		ret = dev_set_mac_address(tun->dev, &ifr.ifr_hwaddr);
+		break;
+
+	case TUNGETSNDBUF:
+		sndbuf = tfile->socket.sk->sk_sndbuf;
+		if (copy_to_user(argp, &sndbuf, sizeof(sndbuf)))
+			ret = -EFAULT;
+		break;
+
+	case TUNSETSNDBUF:
+		if (copy_from_user(&sndbuf, argp, sizeof(sndbuf))) {
+			ret = -EFAULT;
+			break;
+		}
+
+		tun->sndbuf = sndbuf;
+		tun_set_sndbuf(tun);
+		break;
+
+	case TUNGETVNETHDRSZ:
+		vnet_hdr_sz = tun->vnet_hdr_sz;
+		if (copy_to_user(argp, &vnet_hdr_sz, sizeof(vnet_hdr_sz)))
+			ret = -EFAULT;
+		break;
+
+	case TUNSETVNETHDRSZ:
+		if (copy_from_user(&vnet_hdr_sz, argp, sizeof(vnet_hdr_sz))) {
+			ret = -EFAULT;
+			break;
+		}
+		if (vnet_hdr_sz < (int)sizeof(struct virtio_net_hdr)) {
+			ret = -EINVAL;
+			break;
+		}
+
+		tun->vnet_hdr_sz = vnet_hdr_sz;
+		break;
+
+	case TUNGETVNETLE:
+		le = !!(tun->flags & TUN_VNET_LE);
+		if (put_user(le, (int __user *)argp))
+			ret = -EFAULT;
+		break;
+
+	case TUNSETVNETLE:
+		if (get_user(le, (int __user *)argp)) {
+			ret = -EFAULT;
+			break;
+		}
+		if (le)
+			tun->flags |= TUN_VNET_LE;
+		else
+			tun->flags &= ~TUN_VNET_LE;
+		break;
+
+	case TUNATTACHFILTER:
+		/* Can be set only for TAPs */
+		ret = -EINVAL;
+		if ((tun->flags & TUN_TYPE_MASK) != IFF_TAP)
+			break;
+		ret = -EFAULT;
+		if (copy_from_user(&tun->fprog, argp, sizeof(tun->fprog)))
+			break;
+
+		ret = tun_attach_filter(tun);
+		break;
+
+	case TUNDETACHFILTER:
+		/* Can be set only for TAPs */
+		ret = -EINVAL;
+		if ((tun->flags & TUN_TYPE_MASK) != IFF_TAP)
+			break;
+		ret = 0;
+		tun_detach_filter(tun, tun->numqueues);
+		break;
+
+	case TUNGETFILTER:
+		ret = -EINVAL;
+		if ((tun->flags & TUN_TYPE_MASK) != IFF_TAP)
+			break;
+		ret = -EFAULT;
+		if (copy_to_user(argp, &tun->fprog, sizeof(tun->fprog)))
+			break;
+		ret = 0;
+		break;
+
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+unlock:
+	rtnl_unlock();
+	if (tun)
+		tun_put(tun);
+	return ret;
+}
+
+static long tun_chr_ioctl(struct file *file,
+			  unsigned int cmd, unsigned long arg)
+{
+	return __tun_chr_ioctl(file, cmd, arg, sizeof (struct ifreq));
+}
+
+#ifdef CONFIG_COMPAT
+static long tun_chr_compat_ioctl(struct file *file,
+			 unsigned int cmd, unsigned long arg)
+{
+	switch (cmd) {
+	case TUNSETIFF:
+	case TUNGETIFF:
+	case TUNSETTXFILTER:
+	case TUNGETSNDBUF:
+	case TUNSETSNDBUF:
+	case SIOCGIFHWADDR:
+	case SIOCSIFHWADDR:
+		arg = (unsigned long)compat_ptr(arg);
+		break;
+	default:
+		arg = (compat_ulong_t)arg;
+		break;
+	}
+
+	/*
+	 * compat_ifreq is shorter than ifreq, so we must not access beyond
+	 * the end of that structure. All fields that are used in this
+	 * driver are compatible though, we don't need to convert the
+	 * contents.
+	 */
+	return __tun_chr_ioctl(file, cmd, arg, sizeof(struct compat_ifreq));
+}
+#endif /* CONFIG_COMPAT */
+
+static int tun_chr_fasync(int fd, struct file *file, int on)
+{
+	struct tun_file *tfile = file->private_data;
+	int ret;
+
+	if ((ret = fasync_helper(fd, file, on, &tfile->fasync)) < 0)
+		goto out;
+
+	if (on) {
+		__f_setown(file, task_pid(current), PIDTYPE_PID, 0);
+		tfile->flags |= TUN_FASYNC;
+	} else
+		tfile->flags &= ~TUN_FASYNC;
+	ret = 0;
+out:
+	return ret;
+}
+
+static int tun_chr_open(struct inode *inode, struct file * file)
+{
+	struct tun_file *tfile;
+
+	DBG1(KERN_INFO, "tunX: tun_chr_open\n");
+
+	tfile = (struct tun_file *)sk_alloc(&init_net, AF_UNSPEC, GFP_KERNEL,
+					    &tun_proto);
+	if (!tfile)
+		return -ENOMEM;
+	RCU_INIT_POINTER(tfile->tun, NULL);
+	tfile->net = get_net(current->nsproxy->net_ns);
+	tfile->flags = 0;
+	tfile->ifindex = 0;
+
+	init_waitqueue_head(&tfile->wq.wait);
+	RCU_INIT_POINTER(tfile->socket.wq, &tfile->wq);
+
+	tfile->socket.file = file;
+	tfile->socket.ops = &tun_socket_ops;
+
+	sock_init_data(&tfile->socket, &tfile->sk);
+	sk_change_net(&tfile->sk, tfile->net);
+
+	tfile->sk.sk_write_space = tun_sock_write_space;
+	tfile->sk.sk_sndbuf = INT_MAX;
+
+	file->private_data = tfile;
+	set_bit(SOCK_EXTERNALLY_ALLOCATED, &tfile->socket.flags);
+	INIT_LIST_HEAD(&tfile->next);
+
+	sock_set_flag(&tfile->sk, SOCK_ZEROCOPY);
+
+	return 0;
+}
+
+static int tun_chr_close(struct inode *inode, struct file *file)
+{
+	struct tun_file *tfile = file->private_data;
+	struct net *net = tfile->net;
+
+	tun_detach(tfile, true);
+	put_net(net);
+
+	return 0;
+}
+
+#ifdef CONFIG_PROC_FS
+static void tun_chr_show_fdinfo(struct seq_file *m, struct file *f)
+{
+	struct tun_struct *tun;
+	struct ifreq ifr;
+
+	memset(&ifr, 0, sizeof(ifr));
+
+	rtnl_lock();
+	tun = tun_get(f);
+	if (tun)
+		tun_get_iff(current->nsproxy->net_ns, tun, &ifr);
+	rtnl_unlock();
+
+	if (tun)
+		tun_put(tun);
+
+	seq_printf(m, "iff:\t%s\n", ifr.ifr_name);
+}
+#endif
+
+static const struct file_operations tun_fops = {
+	.owner	= THIS_MODULE,
+	.llseek = no_llseek,
+	.read_iter  = tun_chr_read_iter,
+	.write_iter = tun_chr_write_iter,
+	.poll	= tun_chr_poll,
+	.unlocked_ioctl	= tun_chr_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl = tun_chr_compat_ioctl,
+#endif
+	.open	= tun_chr_open,
+	.release = tun_chr_close,
+	.fasync = tun_chr_fasync,
+#ifdef CONFIG_PROC_FS
+	.show_fdinfo = tun_chr_show_fdinfo,
+#endif
+};
+
+static struct miscdevice tun_miscdev = {
+	.minor = TUN_MINOR,
+	.name = "tun",
+	.nodename = "net/tun",
+	.fops = &tun_fops,
+};
+
+/* ethtool interface */
+
+static int tun_get_settings(struct net_device *dev, struct ethtool_cmd *cmd)
+{
+	cmd->supported		= 0;
+	cmd->advertising	= 0;
+	ethtool_cmd_speed_set(cmd, SPEED_10);
+	cmd->duplex		= DUPLEX_FULL;
+	cmd->port		= PORT_TP;
+	cmd->phy_address	= 0;
+	cmd->transceiver	= XCVR_INTERNAL;
+	cmd->autoneg		= AUTONEG_DISABLE;
+	cmd->maxtxpkt		= 0;
+	cmd->maxrxpkt		= 0;
+	return 0;
+}
+
+static void tun_get_drvinfo(struct net_device *dev, struct ethtool_drvinfo *info)
+{
+	struct tun_struct *tun = netdev_priv(dev);
+
+	strlcpy(info->driver, DRV_NAME, sizeof(info->driver));
+	strlcpy(info->version, DRV_VERSION, sizeof(info->version));
+
+	switch (tun->flags & TUN_TYPE_MASK) {
+	case IFF_TUN:
+		strlcpy(info->bus_info, "tun", sizeof(info->bus_info));
+		break;
+	case IFF_TAP:
+		strlcpy(info->bus_info, "tap", sizeof(info->bus_info));
+		break;
+	}
+}
+
+static u32 tun_get_msglevel(struct net_device *dev)
+{
+#ifdef TUN_DEBUG
+	struct tun_struct *tun = netdev_priv(dev);
+	return tun->debug;
+#else
+	return -EOPNOTSUPP;
+#endif
+}
+
+static void tun_set_msglevel(struct net_device *dev, u32 value)
+{
+#ifdef TUN_DEBUG
+	struct tun_struct *tun = netdev_priv(dev);
+	tun->debug = value;
+#endif
+}
+
+static const struct ethtool_ops tun_ethtool_ops = {
+	.get_settings	= tun_get_settings,
+	.get_drvinfo	= tun_get_drvinfo,
+	.get_msglevel	= tun_get_msglevel,
+	.set_msglevel	= tun_set_msglevel,
+	.get_link	= ethtool_op_get_link,
+	.get_ts_info	= ethtool_op_get_ts_info,
+};
+
+
+static int __init tun_init(void)
+{
+	int ret = 0;
+
+	pr_info("%s, %s\n", DRV_DESCRIPTION, DRV_VERSION);
+	pr_info("%s\n", DRV_COPYRIGHT);
+
+	ret = rtnl_link_register(&tun_link_ops);
+	if (ret) {
+		pr_err("Can't register link_ops\n");
+		goto err_linkops;
+	}
+
+	ret = misc_register(&tun_miscdev);
+	if (ret) {
+		pr_err("Can't register misc device %d\n", TUN_MINOR);
+		goto err_misc;
+	}
+	return  0;
+err_misc:
+	rtnl_link_unregister(&tun_link_ops);
+err_linkops:
+	return ret;
+}
+
+static void tun_cleanup(void)
+{
+	misc_deregister(&tun_miscdev);
+	rtnl_link_unregister(&tun_link_ops);
+}
+
+/* Get an underlying socket object from tun file.  Returns error unless file is
+ * attached to a device.  The returned object works like a packet socket, it
+ * can be used for sock_sendmsg/sock_recvmsg.  The caller is responsible for
+ * holding a reference to the file for as long as the socket is in use. */
+struct socket *tun_get_socket(struct file *file)
+{
+	struct tun_file *tfile;
+	if (file->f_op != &tun_fops)
+		return ERR_PTR(-EINVAL);
+	tfile = file->private_data;
+	if (!tfile)
+		return ERR_PTR(-EBADFD);
+	return &tfile->socket;
+}
+EXPORT_SYMBOL_GPL(tun_get_socket);
+
+module_init(tun_init);
+module_exit(tun_cleanup);
+MODULE_DESCRIPTION(DRV_DESCRIPTION);
+MODULE_AUTHOR(DRV_COPYRIGHT);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(TUN_MINOR);
+MODULE_ALIAS("devname:net/tun");