Revert "[PATCH] bcm43xx: Fix deviation from specifications in set_baseband_attenuation"

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / net / tun.c

/*
 *  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:
 *
 *  Brian Braunstein <linuxkernel@bristyle.com> 2007/03/23
 *    Fixed hw address handling.  Now net_device.dev_addr is kept consistent
 *    with tun.dev_addr when the address is set by this module.
 *
 *  Mike Kershaw <dragorn@kismetwireless.net> 2005/08/14
 *    Add TUNSETLINK ioctl to set the link encapsulation
 *
 *  Mark Smith <markzzzsmith@yahoo.com.au>
 *   Use random_ether_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 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/if.h>
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/if_tun.h>
#include <linux/crc32.h>

#include <asm/system.h>
#include <asm/uaccess.h>

#ifdef TUN_DEBUG
static int debug;
#endif

/* Network device part of the driver */

static LIST_HEAD(tun_dev_list);
static const struct ethtool_ops tun_ethtool_ops;

/* Net device open. */
static int tun_net_open(struct net_device *dev)
{
        netif_start_queue(dev);
        return 0;
}

/* Net device close. */
static int tun_net_close(struct net_device *dev)
{
        netif_stop_queue(dev);
        return 0;
}

/* Net device start xmit */
static int tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct tun_struct *tun = netdev_priv(dev);

        DBG(KERN_INFO "%s: tun_net_xmit %d\n", tun->dev->name, skb->len);

        /* Drop packet if interface is not attached */
        if (!tun->attached)
                goto drop;

        /* Packet dropping */
        if (skb_queue_len(&tun->readq) >= dev->tx_queue_len) {
                if (!(tun->flags & TUN_ONE_QUEUE)) {
                        /* Normal queueing mode. */
                        /* Packet scheduler handles dropping of further packets. */
                        netif_stop_queue(dev);

                        /* We won't see all dropped packets individually, so overrun
                         * error is more appropriate. */
                        tun->stats.tx_fifo_errors++;
                } else {
                        /* Single queue mode.
                         * Driver handles dropping of all packets itself. */
                        goto drop;
                }
        }

        /* Queue packet */
        skb_queue_tail(&tun->readq, skb);
        dev->trans_start = jiffies;

        /* Notify and wake up reader process */
        if (tun->flags & TUN_FASYNC)
                kill_fasync(&tun->fasync, SIGIO, POLL_IN);
        wake_up_interruptible(&tun->read_wait);
        return 0;

drop:
        tun->stats.tx_dropped++;
        kfree_skb(skb);
        return 0;
}

/** Add the specified Ethernet address to this multicast filter. */
static void
add_multi(u32* filter, const u8* addr)
{
        int bit_nr = ether_crc(ETH_ALEN, addr) >> 26;
        filter[bit_nr >> 5] |= 1 << (bit_nr & 31);
}

/** Remove the specified Ethernet addres from this multicast filter. */
static void
del_multi(u32* filter, const u8* addr)
{
        int bit_nr = ether_crc(ETH_ALEN, addr) >> 26;
        filter[bit_nr >> 5] &= ~(1 << (bit_nr & 31));
}

/** Update the list of multicast groups to which the network device belongs.
 * This list is used to filter packets being sent from the character device to
 * the network device. */
static void
tun_net_mclist(struct net_device *dev)
{
        struct tun_struct *tun = netdev_priv(dev);
        const struct dev_mc_list *mclist;
        int i;
        DBG(KERN_DEBUG "%s: tun_net_mclist: mc_count %d\n",
                        dev->name, dev->mc_count);
        memset(tun->chr_filter, 0, sizeof tun->chr_filter);
        for (i = 0, mclist = dev->mc_list; i < dev->mc_count && mclist != NULL;
                        i++, mclist = mclist->next) {
                add_multi(tun->net_filter, mclist->dmi_addr);
                DBG(KERN_DEBUG "%s: tun_net_mclist: %x:%x:%x:%x:%x:%x\n",
                                dev->name,
                                mclist->dmi_addr[0], mclist->dmi_addr[1], mclist->dmi_addr[2],
                                mclist->dmi_addr[3], mclist->dmi_addr[4], mclist->dmi_addr[5]);
        }
}

static struct net_device_stats *tun_net_stats(struct net_device *dev)
{
        struct tun_struct *tun = netdev_priv(dev);
        return &tun->stats;
}

/* 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 TUN_TUN_DEV:
                /* 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 TUN_TAP_DEV:
                /* Ethernet TAP Device */
                dev->set_multicast_list = tun_net_mclist;

                ether_setup(dev);

                /* random address already created for us by tun_set_iff, use it */
                memcpy(dev->dev_addr, tun->dev_addr, min(sizeof(tun->dev_addr), sizeof(dev->dev_addr)) );

                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_struct *tun = file->private_data;
        unsigned int mask = POLLOUT | POLLWRNORM;

        if (!tun)
                return -EBADFD;

        DBG(KERN_INFO "%s: tun_chr_poll\n", tun->dev->name);

        poll_wait(file, &tun->read_wait, wait);

        if (!skb_queue_empty(&tun->readq))
                mask |= POLLIN | POLLRDNORM;

        return mask;
}

/* Get packet from user space buffer */
static __inline__ ssize_t tun_get_user(struct tun_struct *tun, struct iovec *iv, size_t count)
{
        struct tun_pi pi = { 0, __constant_htons(ETH_P_IP) };
        struct sk_buff *skb;
        size_t len = count, align = 0;

        if (!(tun->flags & TUN_NO_PI)) {
                if ((len -= sizeof(pi)) > count)
                        return -EINVAL;

                if(memcpy_fromiovec((void *)&pi, iv, sizeof(pi)))
                        return -EFAULT;
        }

        if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV)
                align = NET_IP_ALIGN;

        if (!(skb = alloc_skb(len + align, GFP_KERNEL))) {
                tun->stats.rx_dropped++;
                return -ENOMEM;
        }

        if (align)
                skb_reserve(skb, align);
        if (memcpy_fromiovec(skb_put(skb, len), iv, len)) {
                tun->stats.rx_dropped++;
                kfree_skb(skb);
                return -EFAULT;
        }

        switch (tun->flags & TUN_TYPE_MASK) {
        case TUN_TUN_DEV:
                skb_reset_mac_header(skb);
                skb->protocol = pi.proto;
                skb->dev = tun->dev;
                break;
        case TUN_TAP_DEV:
                skb->protocol = eth_type_trans(skb, tun->dev);
                break;
        };

        if (tun->flags & TUN_NOCHECKSUM)
                skb->ip_summed = CHECKSUM_UNNECESSARY;

        netif_rx_ni(skb);
        tun->dev->last_rx = jiffies;

        tun->stats.rx_packets++;
        tun->stats.rx_bytes += len;

        return count;
}

static inline size_t iov_total(const struct iovec *iv, unsigned long count)
{
        unsigned long i;
        size_t len;

        for (i = 0, len = 0; i < count; i++)
                len += iv[i].iov_len;

        return len;
}

static ssize_t tun_chr_aio_write(struct kiocb *iocb, const struct iovec *iv,
                              unsigned long count, loff_t pos)
{
        struct tun_struct *tun = iocb->ki_filp->private_data;

        if (!tun)
                return -EBADFD;

        DBG(KERN_INFO "%s: tun_chr_write %ld\n", tun->dev->name, count);

        return tun_get_user(tun, (struct iovec *) iv, iov_total(iv, count));
}

/* Put packet to the user space buffer */
static __inline__ ssize_t tun_put_user(struct tun_struct *tun,
                                       struct sk_buff *skb,
                                       struct iovec *iv, int len)
{
        struct tun_pi pi = { 0, skb->protocol };
        ssize_t total = 0;

        if (!(tun->flags & TUN_NO_PI)) {
                if ((len -= sizeof(pi)) < 0)
                        return -EINVAL;

                if (len < skb->len) {
                        /* Packet will be striped */
                        pi.flags |= TUN_PKT_STRIP;
                }

                if (memcpy_toiovec(iv, (void *) &pi, sizeof(pi)))
                        return -EFAULT;
                total += sizeof(pi);
        }

        len = min_t(int, skb->len, len);

        skb_copy_datagram_iovec(skb, 0, iv, len);
        total += len;

        tun->stats.tx_packets++;
        tun->stats.tx_bytes += len;

        return total;
}

static ssize_t tun_chr_aio_read(struct kiocb *iocb, const struct iovec *iv,
                            unsigned long count, loff_t pos)
{
        struct file *file = iocb->ki_filp;
        struct tun_struct *tun = file->private_data;
        DECLARE_WAITQUEUE(wait, current);
        struct sk_buff *skb;
        ssize_t len, ret = 0;

        if (!tun)
                return -EBADFD;

        DBG(KERN_INFO "%s: tun_chr_read\n", tun->dev->name);

        len = iov_total(iv, count);
        if (len < 0)
                return -EINVAL;

        add_wait_queue(&tun->read_wait, &wait);
        while (len) {
                const u8 ones[ ETH_ALEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
                u8 addr[ ETH_ALEN];
                int bit_nr;

                current->state = TASK_INTERRUPTIBLE;

                /* Read frames from the queue */
                if (!(skb=skb_dequeue(&tun->readq))) {
                        if (file->f_flags & O_NONBLOCK) {
                                ret = -EAGAIN;
                                break;
                        }
                        if (signal_pending(current)) {
                                ret = -ERESTARTSYS;
                                break;
                        }

                        /* Nothing to read, let's sleep */
                        schedule();
                        continue;
                }
                netif_wake_queue(tun->dev);

                /** Decide whether to accept this packet. This code is designed to
                 * behave identically to an Ethernet interface. Accept the packet if
                 * - we are promiscuous.
                 * - the packet is addressed to us.
                 * - the packet is broadcast.
                 * - the packet is multicast and
                 *   - we are multicast promiscous.
                 *   - we belong to the multicast group.
                 */
                skb_copy_from_linear_data(skb, addr, min_t(size_t, sizeof addr,
                                                                   skb->len));
                bit_nr = ether_crc(sizeof addr, addr) >> 26;
                if ((tun->if_flags & IFF_PROMISC) ||
                                memcmp(addr, tun->dev_addr, sizeof addr) == 0 ||
                                memcmp(addr, ones, sizeof addr) == 0 ||
                                (((addr[0] == 1 && addr[1] == 0 && addr[2] == 0x5e) ||
                                  (addr[0] == 0x33 && addr[1] == 0x33)) &&
                                 ((tun->if_flags & IFF_ALLMULTI) ||
                                  (tun->chr_filter[bit_nr >> 5] & (1 << (bit_nr & 31)))))) {
                        DBG(KERN_DEBUG "%s: tun_chr_readv: accepted: %x:%x:%x:%x:%x:%x\n",
                                        tun->dev->name, addr[0], addr[1], addr[2],
                                        addr[3], addr[4], addr[5]);
                        ret = tun_put_user(tun, skb, (struct iovec *) iv, len);
                        kfree_skb(skb);
                        break;
                } else {
                        DBG(KERN_DEBUG "%s: tun_chr_readv: rejected: %x:%x:%x:%x:%x:%x\n",
                                        tun->dev->name, addr[0], addr[1], addr[2],
                                        addr[3], addr[4], addr[5]);
                        kfree_skb(skb);
                        continue;
                }
        }

        current->state = TASK_RUNNING;
        remove_wait_queue(&tun->read_wait, &wait);

        return ret;
}

static void tun_setup(struct net_device *dev)
{
        struct tun_struct *tun = netdev_priv(dev);

        skb_queue_head_init(&tun->readq);
        init_waitqueue_head(&tun->read_wait);

        tun->owner = -1;
        tun->group = -1;

        SET_MODULE_OWNER(dev);
        dev->open = tun_net_open;
        dev->hard_start_xmit = tun_net_xmit;
        dev->stop = tun_net_close;
        dev->get_stats = tun_net_stats;
        dev->ethtool_ops = &tun_ethtool_ops;
        dev->destructor = free_netdev;
}

static struct tun_struct *tun_get_by_name(const char *name)
{
        struct tun_struct *tun;

        ASSERT_RTNL();
        list_for_each_entry(tun, &tun_dev_list, list) {
                if (!strncmp(tun->dev->name, name, IFNAMSIZ))
                    return tun;
        }

        return NULL;
}

static int tun_set_iff(struct file *file, struct ifreq *ifr)
{
        struct tun_struct *tun;
        struct net_device *dev;
        int err;

        tun = tun_get_by_name(ifr->ifr_name);
        if (tun) {
                if (tun->attached)
                        return -EBUSY;

                /* Check permissions */
                if (((tun->owner != -1 &&
                      current->euid != tun->owner) ||
                     (tun->group != -1 &&
                      current->egid != tun->group)) &&
                     !capable(CAP_NET_ADMIN))
                        return -EPERM;
        }
        else if (__dev_get_by_name(ifr->ifr_name))
                return -EINVAL;
        else {
                char *name;
                unsigned long flags = 0;

                err = -EINVAL;

                if (!capable(CAP_NET_ADMIN))
                        return -EPERM;

                /* Set dev type */
                if (ifr->ifr_flags & IFF_TUN) {
                        /* TUN device */
                        flags |= TUN_TUN_DEV;
                        name = "tun%d";
                } else if (ifr->ifr_flags & IFF_TAP) {
                        /* TAP device */
                        flags |= TUN_TAP_DEV;
                        name = "tap%d";
                } else
                        goto failed;

                if (*ifr->ifr_name)
                        name = ifr->ifr_name;

                dev = alloc_netdev(sizeof(struct tun_struct), name,
                                   tun_setup);
                if (!dev)
                        return -ENOMEM;

                tun = netdev_priv(dev);
                tun->dev = dev;
                tun->flags = flags;
                /* Be promiscuous by default to maintain previous behaviour. */
                tun->if_flags = IFF_PROMISC;
                /* Generate random Ethernet address. */
                *(u16 *)tun->dev_addr = htons(0x00FF);
                get_random_bytes(tun->dev_addr + sizeof(u16), 4);
                memset(tun->chr_filter, 0, sizeof tun->chr_filter);

                tun_net_init(dev);

                if (strchr(dev->name, '%')) {
                        err = dev_alloc_name(dev, dev->name);
                        if (err < 0)
                                goto err_free_dev;
                }

                err = register_netdevice(tun->dev);
                if (err < 0)
                        goto err_free_dev;

                list_add(&tun->list, &tun_dev_list);
        }

        DBG(KERN_INFO "%s: tun_set_iff\n", tun->dev->name);

        if (ifr->ifr_flags & IFF_NO_PI)
                tun->flags |= TUN_NO_PI;

        if (ifr->ifr_flags & IFF_ONE_QUEUE)
                tun->flags |= TUN_ONE_QUEUE;

        file->private_data = tun;
        tun->attached = 1;

        strcpy(ifr->ifr_name, tun->dev->name);
        return 0;

 err_free_dev:
        free_netdev(dev);
 failed:
        return err;
}

static int tun_chr_ioctl(struct inode *inode, struct file *file,
                         unsigned int cmd, unsigned long arg)
{
        struct tun_struct *tun = file->private_data;
        void __user* argp = (void __user*)arg;
        struct ifreq ifr;

        if (cmd == TUNSETIFF || _IOC_TYPE(cmd) == 0x89)
                if (copy_from_user(&ifr, argp, sizeof ifr))
                        return -EFAULT;

        if (cmd == TUNSETIFF && !tun) {
                int err;

                ifr.ifr_name[IFNAMSIZ-1] = '\0';

                rtnl_lock();
                err = tun_set_iff(file, &ifr);
                rtnl_unlock();

                if (err)
                        return err;

                if (copy_to_user(argp, &ifr, sizeof(ifr)))
                        return -EFAULT;
                return 0;
        }

        if (!tun)
                return -EBADFD;

        DBG(KERN_INFO "%s: tun_chr_ioctl cmd %d\n", tun->dev->name, cmd);

        switch (cmd) {
        case TUNSETNOCSUM:
                /* Disable/Enable checksum */
                if (arg)
                        tun->flags |= TUN_NOCHECKSUM;
                else
                        tun->flags &= ~TUN_NOCHECKSUM;

                DBG(KERN_INFO "%s: checksum %s\n",
                    tun->dev->name, arg ? "disabled" : "enabled");
                break;

        case TUNSETPERSIST:
                /* Disable/Enable persist mode */
                if (arg)
                        tun->flags |= TUN_PERSIST;
                else
                        tun->flags &= ~TUN_PERSIST;

                DBG(KERN_INFO "%s: persist %s\n",
                    tun->dev->name, arg ? "disabled" : "enabled");
                break;

        case TUNSETOWNER:
                /* Set owner of the device */
                tun->owner = (uid_t) arg;

                DBG(KERN_INFO "%s: owner set to %d\n", tun->dev->name, tun->owner);
                break;

        case TUNSETGROUP:
                /* Set group of the device */
                tun->group= (gid_t) arg;

                DBG(KERN_INFO "%s: group set to %d\n", tun->dev->name, tun->group);
                break;

        case TUNSETLINK:
                /* Only allow setting the type when the interface is down */
                if (tun->dev->flags & IFF_UP) {
                        DBG(KERN_INFO "%s: Linktype set failed because interface is up\n",
                                tun->dev->name);
                        return -EBUSY;
                } else {
                        tun->dev->type = (int) arg;
                        DBG(KERN_INFO "%s: linktype set to %d\n", tun->dev->name, tun->dev->type);
                }
                break;

#ifdef TUN_DEBUG
        case TUNSETDEBUG:
                tun->debug = arg;
                break;
#endif

        case SIOCGIFFLAGS:
                ifr.ifr_flags = tun->if_flags;
                if (copy_to_user( argp, &ifr, sizeof ifr))
                        return -EFAULT;
                return 0;

        case SIOCSIFFLAGS:
                /** Set the character device's interface flags. Currently only
                 * IFF_PROMISC and IFF_ALLMULTI are used. */
                tun->if_flags = ifr.ifr_flags;
                DBG(KERN_INFO "%s: interface flags 0x%lx\n",
                                tun->dev->name, tun->if_flags);
                return 0;

        case SIOCGIFHWADDR:
                /* Note: the actual net device's address may be different */
                memcpy(ifr.ifr_hwaddr.sa_data, tun->dev_addr,
                                min(sizeof ifr.ifr_hwaddr.sa_data, sizeof tun->dev_addr));
                if (copy_to_user( argp, &ifr, sizeof ifr))
                        return -EFAULT;
                return 0;

        case SIOCSIFHWADDR:
        {
                /* try to set the actual net device's hw address */
                int ret = dev_set_mac_address(tun->dev, &ifr.ifr_hwaddr);

                if (ret == 0) {
                        /** Set the character device's hardware address. This is used when
                         * filtering packets being sent from the network device to the character
                         * device. */
                        memcpy(tun->dev_addr, ifr.ifr_hwaddr.sa_data,
                                        min(sizeof ifr.ifr_hwaddr.sa_data, sizeof tun->dev_addr));
                        DBG(KERN_DEBUG "%s: set hardware address: %x:%x:%x:%x:%x:%x\n",
                                        tun->dev->name,
                                        tun->dev_addr[0], tun->dev_addr[1], tun->dev_addr[2],
                                        tun->dev_addr[3], tun->dev_addr[4], tun->dev_addr[5]);
                }

                return  ret;
        }

        case SIOCADDMULTI:
                /** Add the specified group to the character device's multicast filter
                 * list. */
                add_multi(tun->chr_filter, ifr.ifr_hwaddr.sa_data);
                DBG(KERN_DEBUG "%s: add multi: %x:%x:%x:%x:%x:%x\n",
                                tun->dev->name,
                                (u8)ifr.ifr_hwaddr.sa_data[0], (u8)ifr.ifr_hwaddr.sa_data[1],
                                (u8)ifr.ifr_hwaddr.sa_data[2], (u8)ifr.ifr_hwaddr.sa_data[3],
                                (u8)ifr.ifr_hwaddr.sa_data[4], (u8)ifr.ifr_hwaddr.sa_data[5]);
                return 0;

        case SIOCDELMULTI:
                /** Remove the specified group from the character device's multicast
                 * filter list. */
                del_multi(tun->chr_filter, ifr.ifr_hwaddr.sa_data);
                DBG(KERN_DEBUG "%s: del multi: %x:%x:%x:%x:%x:%x\n",
                                tun->dev->name,
                                (u8)ifr.ifr_hwaddr.sa_data[0], (u8)ifr.ifr_hwaddr.sa_data[1],
                                (u8)ifr.ifr_hwaddr.sa_data[2], (u8)ifr.ifr_hwaddr.sa_data[3],
                                (u8)ifr.ifr_hwaddr.sa_data[4], (u8)ifr.ifr_hwaddr.sa_data[5]);
                return 0;

        default:
                return -EINVAL;
        };

        return 0;
}

static int tun_chr_fasync(int fd, struct file *file, int on)
{
        struct tun_struct *tun = file->private_data;
        int ret;

        if (!tun)
                return -EBADFD;

        DBG(KERN_INFO "%s: tun_chr_fasync %d\n", tun->dev->name, on);

        if ((ret = fasync_helper(fd, file, on, &tun->fasync)) < 0)
                return ret;

        if (on) {
                ret = __f_setown(file, task_pid(current), PIDTYPE_PID, 0);
                if (ret)
                        return ret;
                tun->flags |= TUN_FASYNC;
        } else
                tun->flags &= ~TUN_FASYNC;

        return 0;
}

static int tun_chr_open(struct inode *inode, struct file * file)
{
        DBG1(KERN_INFO "tunX: tun_chr_open\n");
        file->private_data = NULL;
        return 0;
}

static int tun_chr_close(struct inode *inode, struct file *file)
{
        struct tun_struct *tun = file->private_data;

        if (!tun)
                return 0;

        DBG(KERN_INFO "%s: tun_chr_close\n", tun->dev->name);

        tun_chr_fasync(-1, file, 0);

        rtnl_lock();

        /* Detach from net device */
        file->private_data = NULL;
        tun->attached = 0;

        /* Drop read queue */
        skb_queue_purge(&tun->readq);

        if (!(tun->flags & TUN_PERSIST)) {
                list_del(&tun->list);
                unregister_netdevice(tun->dev);
        }

        rtnl_unlock();

        return 0;
}

static const struct file_operations tun_fops = {
        .owner  = THIS_MODULE,
        .llseek = no_llseek,
        .read  = do_sync_read,
        .aio_read  = tun_chr_aio_read,
        .write = do_sync_write,
        .aio_write = tun_chr_aio_write,
        .poll   = tun_chr_poll,
        .ioctl  = tun_chr_ioctl,
        .open   = tun_chr_open,
        .release = tun_chr_close,
        .fasync = tun_chr_fasync
};

static struct miscdevice tun_miscdev = {
        .minor = TUN_MINOR,
        .name = "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;
        cmd->speed              = 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);

        strcpy(info->driver, DRV_NAME);
        strcpy(info->version, DRV_VERSION);
        strcpy(info->fw_version, "N/A");

        switch (tun->flags & TUN_TYPE_MASK) {
        case TUN_TUN_DEV:
                strcpy(info->bus_info, "tun");
                break;
        case TUN_TAP_DEV:
                strcpy(info->bus_info, "tap");
                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 u32 tun_get_link(struct net_device *dev)
{
        struct tun_struct *tun = netdev_priv(dev);
        return tun->attached;
}

static u32 tun_get_rx_csum(struct net_device *dev)
{
        struct tun_struct *tun = netdev_priv(dev);
        return (tun->flags & TUN_NOCHECKSUM) == 0;
}

static int tun_set_rx_csum(struct net_device *dev, u32 data)
{
        struct tun_struct *tun = netdev_priv(dev);
        if (data)
                tun->flags &= ~TUN_NOCHECKSUM;
        else
                tun->flags |= TUN_NOCHECKSUM;
        return 0;
}

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       = tun_get_link,
        .get_rx_csum    = tun_get_rx_csum,
        .set_rx_csum    = tun_set_rx_csum
};

static int __init tun_init(void)
{
        int ret = 0;

        printk(KERN_INFO "tun: %s, %s\n", DRV_DESCRIPTION, DRV_VERSION);
        printk(KERN_INFO "tun: %s\n", DRV_COPYRIGHT);

        ret = misc_register(&tun_miscdev);
        if (ret)
                printk(KERN_ERR "tun: Can't register misc device %d\n", TUN_MINOR);
        return ret;
}

static void tun_cleanup(void)
{
        struct tun_struct *tun, *nxt;

        misc_deregister(&tun_miscdev);

        rtnl_lock();
        list_for_each_entry_safe(tun, nxt, &tun_dev_list, list) {
                DBG(KERN_INFO "%s cleaned up\n", tun->dev->name);
                unregister_netdevice(tun->dev);
        }
        rtnl_unlock();

}

module_init(tun_init);
module_exit(tun_cleanup);
MODULE_DESCRIPTION(DRV_DESCRIPTION);
MODULE_AUTHOR(DRV_COPYRIGHT);
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(TUN_MINOR);