path: root/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/smp_lock.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 <linux/nsproxy.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>

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

/* Uncomment to enable debugging */
/* #define TUN_DEBUG 1 */

#ifdef TUN_DEBUG
static int debug;

#define DBG  if(tun->debug)printk
#define DBG1 if(debug==2)printk
#else
#define DBG( a... )
#define DBG1( a... )
#endif

struct tun_struct {
	struct list_head        list;
	unsigned long 		flags;
	int			attached;
	uid_t			owner;
	gid_t			group;

	wait_queue_head_t	read_wait;
	struct sk_buff_head	readq;

	struct net_device	*dev;

	struct fasync_struct    *fasync;

	unsigned long if_flags;
	u8 dev_addr[ETH_ALEN];
	u32 chr_filter[2];
	u32 net_filter[2];

#ifdef TUN_DEBUG
	int debug;
#endif
};

/* Network device part of the driver */

static unsigned int tun_net_id;
struct tun_net {
	struct list_head 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. */
			dev->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:
	dev->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;
	DECLARE_MAC_BUF(mac);