xref: /linux/drivers/net/tun.c (revision 14b42963f64b98ab61fa9723c03d71aa5ef4f862)
1 /*
2  *  TUN - Universal TUN/TAP device driver.
3  *  Copyright (C) 1999-2002 Maxim Krasnyansky <maxk@qualcomm.com>
4  *
5  *  This program is free software; you can redistribute it and/or modify
6  *  it under the terms of the GNU General Public License as published by
7  *  the Free Software Foundation; either version 2 of the License, or
8  *  (at your option) any later version.
9  *
10  *  This program is distributed in the hope that it will be useful,
11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13  *  GNU General Public License for more details.
14  *
15  *  $Id: tun.c,v 1.15 2002/03/01 02:44:24 maxk Exp $
16  */
17 
18 /*
19  *  Changes:
20  *
21  *  Mike Kershaw <dragorn@kismetwireless.net> 2005/08/14
22  *    Add TUNSETLINK ioctl to set the link encapsulation
23  *
24  *  Mark Smith <markzzzsmith@yahoo.com.au>
25  *   Use random_ether_addr() for tap MAC address.
26  *
27  *  Harald Roelle <harald.roelle@ifi.lmu.de>  2004/04/20
28  *    Fixes in packet dropping, queue length setting and queue wakeup.
29  *    Increased default tx queue length.
30  *    Added ethtool API.
31  *    Minor cleanups
32  *
33  *  Daniel Podlejski <underley@underley.eu.org>
34  *    Modifications for 2.3.99-pre5 kernel.
35  */
36 
37 #define DRV_NAME	"tun"
38 #define DRV_VERSION	"1.6"
39 #define DRV_DESCRIPTION	"Universal TUN/TAP device driver"
40 #define DRV_COPYRIGHT	"(C) 1999-2004 Max Krasnyansky <maxk@qualcomm.com>"
41 
42 #include <linux/module.h>
43 #include <linux/errno.h>
44 #include <linux/kernel.h>
45 #include <linux/major.h>
46 #include <linux/slab.h>
47 #include <linux/poll.h>
48 #include <linux/fcntl.h>
49 #include <linux/init.h>
50 #include <linux/skbuff.h>
51 #include <linux/netdevice.h>
52 #include <linux/etherdevice.h>
53 #include <linux/miscdevice.h>
54 #include <linux/ethtool.h>
55 #include <linux/rtnetlink.h>
56 #include <linux/if.h>
57 #include <linux/if_arp.h>
58 #include <linux/if_ether.h>
59 #include <linux/if_tun.h>
60 #include <linux/crc32.h>
61 
62 #include <asm/system.h>
63 #include <asm/uaccess.h>
64 
65 #ifdef TUN_DEBUG
66 static int debug;
67 #endif
68 
69 /* Network device part of the driver */
70 
71 static LIST_HEAD(tun_dev_list);
72 static struct ethtool_ops tun_ethtool_ops;
73 
74 /* Net device open. */
75 static int tun_net_open(struct net_device *dev)
76 {
77 	netif_start_queue(dev);
78 	return 0;
79 }
80 
81 /* Net device close. */
82 static int tun_net_close(struct net_device *dev)
83 {
84 	netif_stop_queue(dev);
85 	return 0;
86 }
87 
88 /* Net device start xmit */
89 static int tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
90 {
91 	struct tun_struct *tun = netdev_priv(dev);
92 
93 	DBG(KERN_INFO "%s: tun_net_xmit %d\n", tun->dev->name, skb->len);
94 
95 	/* Drop packet if interface is not attached */
96 	if (!tun->attached)
97 		goto drop;
98 
99 	/* Packet dropping */
100 	if (skb_queue_len(&tun->readq) >= dev->tx_queue_len) {
101 		if (!(tun->flags & TUN_ONE_QUEUE)) {
102 			/* Normal queueing mode. */
103 			/* Packet scheduler handles dropping of further packets. */
104 			netif_stop_queue(dev);
105 
106 			/* We won't see all dropped packets individually, so overrun
107 			 * error is more appropriate. */
108 			tun->stats.tx_fifo_errors++;
109 		} else {
110 			/* Single queue mode.
111 			 * Driver handles dropping of all packets itself. */
112 			goto drop;
113 		}
114 	}
115 
116 	/* Queue packet */
117 	skb_queue_tail(&tun->readq, skb);
118 	dev->trans_start = jiffies;
119 
120 	/* Notify and wake up reader process */
121 	if (tun->flags & TUN_FASYNC)
122 		kill_fasync(&tun->fasync, SIGIO, POLL_IN);
123 	wake_up_interruptible(&tun->read_wait);
124 	return 0;
125 
126 drop:
127 	tun->stats.tx_dropped++;
128 	kfree_skb(skb);
129 	return 0;
130 }
131 
132 /** Add the specified Ethernet address to this multicast filter. */
133 static void
134 add_multi(u32* filter, const u8* addr)
135 {
136 	int bit_nr = ether_crc(ETH_ALEN, addr) >> 26;
137 	filter[bit_nr >> 5] |= 1 << (bit_nr & 31);
138 }
139 
140 /** Remove the specified Ethernet addres from this multicast filter. */
141 static void
142 del_multi(u32* filter, const u8* addr)
143 {
144 	int bit_nr = ether_crc(ETH_ALEN, addr) >> 26;
145 	filter[bit_nr >> 5] &= ~(1 << (bit_nr & 31));
146 }
147 
148 /** Update the list of multicast groups to which the network device belongs.
149  * This list is used to filter packets being sent from the character device to
150  * the network device. */
151 static void
152 tun_net_mclist(struct net_device *dev)
153 {
154 	struct tun_struct *tun = netdev_priv(dev);
155 	const struct dev_mc_list *mclist;
156 	int i;
157 	DBG(KERN_DEBUG "%s: tun_net_mclist: mc_count %d\n",
158 			dev->name, dev->mc_count);
159 	memset(tun->chr_filter, 0, sizeof tun->chr_filter);
160 	for (i = 0, mclist = dev->mc_list; i < dev->mc_count && mclist != NULL;
161 			i++, mclist = mclist->next) {
162 		add_multi(tun->net_filter, mclist->dmi_addr);
163 		DBG(KERN_DEBUG "%s: tun_net_mclist: %x:%x:%x:%x:%x:%x\n",
164 				dev->name,
165 				mclist->dmi_addr[0], mclist->dmi_addr[1], mclist->dmi_addr[2],
166 				mclist->dmi_addr[3], mclist->dmi_addr[4], mclist->dmi_addr[5]);
167 	}
168 }
169 
170 static struct net_device_stats *tun_net_stats(struct net_device *dev)
171 {
172 	struct tun_struct *tun = netdev_priv(dev);
173 	return &tun->stats;
174 }
175 
176 /* Initialize net device. */
177 static void tun_net_init(struct net_device *dev)
178 {
179 	struct tun_struct *tun = netdev_priv(dev);
180 
181 	switch (tun->flags & TUN_TYPE_MASK) {
182 	case TUN_TUN_DEV:
183 		/* Point-to-Point TUN Device */
184 		dev->hard_header_len = 0;
185 		dev->addr_len = 0;
186 		dev->mtu = 1500;
187 
188 		/* Zero header length */
189 		dev->type = ARPHRD_NONE;
190 		dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
191 		dev->tx_queue_len = TUN_READQ_SIZE;  /* We prefer our own queue length */
192 		break;
193 
194 	case TUN_TAP_DEV:
195 		/* Ethernet TAP Device */
196 		dev->set_multicast_list = tun_net_mclist;
197 
198 		ether_setup(dev);
199 		random_ether_addr(dev->dev_addr);
200 		dev->tx_queue_len = TUN_READQ_SIZE;  /* We prefer our own queue length */
201 		break;
202 	}
203 }
204 
205 /* Character device part */
206 
207 /* Poll */
208 static unsigned int tun_chr_poll(struct file *file, poll_table * wait)
209 {
210 	struct tun_struct *tun = file->private_data;
211 	unsigned int mask = POLLOUT | POLLWRNORM;
212 
213 	if (!tun)
214 		return -EBADFD;
215 
216 	DBG(KERN_INFO "%s: tun_chr_poll\n", tun->dev->name);
217 
218 	poll_wait(file, &tun->read_wait, wait);
219 
220 	if (!skb_queue_empty(&tun->readq))
221 		mask |= POLLIN | POLLRDNORM;
222 
223 	return mask;
224 }
225 
226 /* Get packet from user space buffer */
227 static __inline__ ssize_t tun_get_user(struct tun_struct *tun, struct iovec *iv, size_t count)
228 {
229 	struct tun_pi pi = { 0, __constant_htons(ETH_P_IP) };
230 	struct sk_buff *skb;
231 	size_t len = count, align = 0;
232 
233 	if (!(tun->flags & TUN_NO_PI)) {
234 		if ((len -= sizeof(pi)) > count)
235 			return -EINVAL;
236 
237 		if(memcpy_fromiovec((void *)&pi, iv, sizeof(pi)))
238 			return -EFAULT;
239 	}
240 
241 	if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV)
242 		align = NET_IP_ALIGN;
243 
244 	if (!(skb = alloc_skb(len + align, GFP_KERNEL))) {
245 		tun->stats.rx_dropped++;
246 		return -ENOMEM;
247 	}
248 
249 	if (align)
250 		skb_reserve(skb, align);
251 	if (memcpy_fromiovec(skb_put(skb, len), iv, len)) {
252 		tun->stats.rx_dropped++;
253 		kfree_skb(skb);
254 		return -EFAULT;
255 	}
256 
257 	skb->dev = tun->dev;
258 	switch (tun->flags & TUN_TYPE_MASK) {
259 	case TUN_TUN_DEV:
260 		skb->mac.raw = skb->data;
261 		skb->protocol = pi.proto;
262 		break;
263 	case TUN_TAP_DEV:
264 		skb->protocol = eth_type_trans(skb, tun->dev);
265 		break;
266 	};
267 
268 	if (tun->flags & TUN_NOCHECKSUM)
269 		skb->ip_summed = CHECKSUM_UNNECESSARY;
270 
271 	netif_rx_ni(skb);
272 	tun->dev->last_rx = jiffies;
273 
274 	tun->stats.rx_packets++;
275 	tun->stats.rx_bytes += len;
276 
277 	return count;
278 }
279 
280 static inline size_t iov_total(const struct iovec *iv, unsigned long count)
281 {
282 	unsigned long i;
283 	size_t len;
284 
285 	for (i = 0, len = 0; i < count; i++)
286 		len += iv[i].iov_len;
287 
288 	return len;
289 }
290 
291 /* Writev */
292 static ssize_t tun_chr_writev(struct file * file, const struct iovec *iv,
293 			      unsigned long count, loff_t *pos)
294 {
295 	struct tun_struct *tun = file->private_data;
296 
297 	if (!tun)
298 		return -EBADFD;
299 
300 	DBG(KERN_INFO "%s: tun_chr_write %ld\n", tun->dev->name, count);
301 
302 	return tun_get_user(tun, (struct iovec *) iv, iov_total(iv, count));
303 }
304 
305 /* Write */
306 static ssize_t tun_chr_write(struct file * file, const char __user * buf,
307 			     size_t count, loff_t *pos)
308 {
309 	struct iovec iv = { (void __user *) buf, count };
310 	return tun_chr_writev(file, &iv, 1, pos);
311 }
312 
313 /* Put packet to the user space buffer */
314 static __inline__ ssize_t tun_put_user(struct tun_struct *tun,
315 				       struct sk_buff *skb,
316 				       struct iovec *iv, int len)
317 {
318 	struct tun_pi pi = { 0, skb->protocol };
319 	ssize_t total = 0;
320 
321 	if (!(tun->flags & TUN_NO_PI)) {
322 		if ((len -= sizeof(pi)) < 0)
323 			return -EINVAL;
324 
325 		if (len < skb->len) {
326 			/* Packet will be striped */
327 			pi.flags |= TUN_PKT_STRIP;
328 		}
329 
330 		if (memcpy_toiovec(iv, (void *) &pi, sizeof(pi)))
331 			return -EFAULT;
332 		total += sizeof(pi);
333 	}
334 
335 	len = min_t(int, skb->len, len);
336 
337 	skb_copy_datagram_iovec(skb, 0, iv, len);
338 	total += len;
339 
340 	tun->stats.tx_packets++;
341 	tun->stats.tx_bytes += len;
342 
343 	return total;
344 }
345 
346 /* Readv */
347 static ssize_t tun_chr_readv(struct file *file, const struct iovec *iv,
348 			    unsigned long count, loff_t *pos)
349 {
350 	struct tun_struct *tun = file->private_data;
351 	DECLARE_WAITQUEUE(wait, current);
352 	struct sk_buff *skb;
353 	ssize_t len, ret = 0;
354 
355 	if (!tun)
356 		return -EBADFD;
357 
358 	DBG(KERN_INFO "%s: tun_chr_read\n", tun->dev->name);
359 
360 	len = iov_total(iv, count);
361 	if (len < 0)
362 		return -EINVAL;
363 
364 	add_wait_queue(&tun->read_wait, &wait);
365 	while (len) {
366 		const u8 ones[ ETH_ALEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
367 		u8 addr[ ETH_ALEN];
368 		int bit_nr;
369 
370 		current->state = TASK_INTERRUPTIBLE;
371 
372 		/* Read frames from the queue */
373 		if (!(skb=skb_dequeue(&tun->readq))) {
374 			if (file->f_flags & O_NONBLOCK) {
375 				ret = -EAGAIN;
376 				break;
377 			}
378 			if (signal_pending(current)) {
379 				ret = -ERESTARTSYS;
380 				break;
381 			}
382 
383 			/* Nothing to read, let's sleep */
384 			schedule();
385 			continue;
386 		}
387 		netif_wake_queue(tun->dev);
388 
389 		/** Decide whether to accept this packet. This code is designed to
390 		 * behave identically to an Ethernet interface. Accept the packet if
391 		 * - we are promiscuous.
392 		 * - the packet is addressed to us.
393 		 * - the packet is broadcast.
394 		 * - the packet is multicast and
395 		 *   - we are multicast promiscous.
396 		 *   - we belong to the multicast group.
397 		 */
398 		memcpy(addr, skb->data,
399 		       min_t(size_t, sizeof addr, skb->len));
400 		bit_nr = ether_crc(sizeof addr, addr) >> 26;
401 		if ((tun->if_flags & IFF_PROMISC) ||
402 				memcmp(addr, tun->dev_addr, sizeof addr) == 0 ||
403 				memcmp(addr, ones, sizeof addr) == 0 ||
404 				(((addr[0] == 1 && addr[1] == 0 && addr[2] == 0x5e) ||
405 				  (addr[0] == 0x33 && addr[1] == 0x33)) &&
406 				 ((tun->if_flags & IFF_ALLMULTI) ||
407 				  (tun->chr_filter[bit_nr >> 5] & (1 << (bit_nr & 31)))))) {
408 			DBG(KERN_DEBUG "%s: tun_chr_readv: accepted: %x:%x:%x:%x:%x:%x\n",
409 					tun->dev->name, addr[0], addr[1], addr[2],
410 					addr[3], addr[4], addr[5]);
411 			ret = tun_put_user(tun, skb, (struct iovec *) iv, len);
412 			kfree_skb(skb);
413 			break;
414 		} else {
415 			DBG(KERN_DEBUG "%s: tun_chr_readv: rejected: %x:%x:%x:%x:%x:%x\n",
416 					tun->dev->name, addr[0], addr[1], addr[2],
417 					addr[3], addr[4], addr[5]);
418 			kfree_skb(skb);
419 			continue;
420 		}
421 	}
422 
423 	current->state = TASK_RUNNING;
424 	remove_wait_queue(&tun->read_wait, &wait);
425 
426 	return ret;
427 }
428 
429 /* Read */
430 static ssize_t tun_chr_read(struct file * file, char __user * buf,
431 			    size_t count, loff_t *pos)
432 {
433 	struct iovec iv = { buf, count };
434 	return tun_chr_readv(file, &iv, 1, pos);
435 }
436 
437 static void tun_setup(struct net_device *dev)
438 {
439 	struct tun_struct *tun = netdev_priv(dev);
440 
441 	skb_queue_head_init(&tun->readq);
442 	init_waitqueue_head(&tun->read_wait);
443 
444 	tun->owner = -1;
445 
446 	SET_MODULE_OWNER(dev);
447 	dev->open = tun_net_open;
448 	dev->hard_start_xmit = tun_net_xmit;
449 	dev->stop = tun_net_close;
450 	dev->get_stats = tun_net_stats;
451 	dev->ethtool_ops = &tun_ethtool_ops;
452 	dev->destructor = free_netdev;
453 }
454 
455 static struct tun_struct *tun_get_by_name(const char *name)
456 {
457 	struct tun_struct *tun;
458 
459 	ASSERT_RTNL();
460 	list_for_each_entry(tun, &tun_dev_list, list) {
461 		if (!strncmp(tun->dev->name, name, IFNAMSIZ))
462 		    return tun;
463 	}
464 
465 	return NULL;
466 }
467 
468 static int tun_set_iff(struct file *file, struct ifreq *ifr)
469 {
470 	struct tun_struct *tun;
471 	struct net_device *dev;
472 	int err;
473 
474 	tun = tun_get_by_name(ifr->ifr_name);
475 	if (tun) {
476 		if (tun->attached)
477 			return -EBUSY;
478 
479 		/* Check permissions */
480 		if (tun->owner != -1 &&
481 		    current->euid != tun->owner && !capable(CAP_NET_ADMIN))
482 			return -EPERM;
483 	}
484 	else if (__dev_get_by_name(ifr->ifr_name))
485 		return -EINVAL;
486 	else {
487 		char *name;
488 		unsigned long flags = 0;
489 
490 		err = -EINVAL;
491 
492 		if (!capable(CAP_NET_ADMIN))
493 			return -EPERM;
494 
495 		/* Set dev type */
496 		if (ifr->ifr_flags & IFF_TUN) {
497 			/* TUN device */
498 			flags |= TUN_TUN_DEV;
499 			name = "tun%d";
500 		} else if (ifr->ifr_flags & IFF_TAP) {
501 			/* TAP device */
502 			flags |= TUN_TAP_DEV;
503 			name = "tap%d";
504 		} else
505 			goto failed;
506 
507 		if (*ifr->ifr_name)
508 			name = ifr->ifr_name;
509 
510 		dev = alloc_netdev(sizeof(struct tun_struct), name,
511 				   tun_setup);
512 		if (!dev)
513 			return -ENOMEM;
514 
515 		tun = netdev_priv(dev);
516 		tun->dev = dev;
517 		tun->flags = flags;
518 		/* Be promiscuous by default to maintain previous behaviour. */
519 		tun->if_flags = IFF_PROMISC;
520 		/* Generate random Ethernet address. */
521 		*(u16 *)tun->dev_addr = htons(0x00FF);
522 		get_random_bytes(tun->dev_addr + sizeof(u16), 4);
523 		memset(tun->chr_filter, 0, sizeof tun->chr_filter);
524 
525 		tun_net_init(dev);
526 
527 		if (strchr(dev->name, '%')) {
528 			err = dev_alloc_name(dev, dev->name);
529 			if (err < 0)
530 				goto err_free_dev;
531 		}
532 
533 		err = register_netdevice(tun->dev);
534 		if (err < 0)
535 			goto err_free_dev;
536 
537 		list_add(&tun->list, &tun_dev_list);
538 	}
539 
540 	DBG(KERN_INFO "%s: tun_set_iff\n", tun->dev->name);
541 
542 	if (ifr->ifr_flags & IFF_NO_PI)
543 		tun->flags |= TUN_NO_PI;
544 
545 	if (ifr->ifr_flags & IFF_ONE_QUEUE)
546 		tun->flags |= TUN_ONE_QUEUE;
547 
548 	file->private_data = tun;
549 	tun->attached = 1;
550 
551 	strcpy(ifr->ifr_name, tun->dev->name);
552 	return 0;
553 
554  err_free_dev:
555 	free_netdev(dev);
556  failed:
557 	return err;
558 }
559 
560 static int tun_chr_ioctl(struct inode *inode, struct file *file,
561 			 unsigned int cmd, unsigned long arg)
562 {
563 	struct tun_struct *tun = file->private_data;
564 	void __user* argp = (void __user*)arg;
565 	struct ifreq ifr;
566 
567 	if (cmd == TUNSETIFF || _IOC_TYPE(cmd) == 0x89)
568 		if (copy_from_user(&ifr, argp, sizeof ifr))
569 			return -EFAULT;
570 
571 	if (cmd == TUNSETIFF && !tun) {
572 		int err;
573 
574 		ifr.ifr_name[IFNAMSIZ-1] = '\0';
575 
576 		rtnl_lock();
577 		err = tun_set_iff(file, &ifr);
578 		rtnl_unlock();
579 
580 		if (err)
581 			return err;
582 
583 		if (copy_to_user(argp, &ifr, sizeof(ifr)))
584 			return -EFAULT;
585 		return 0;
586 	}
587 
588 	if (!tun)
589 		return -EBADFD;
590 
591 	DBG(KERN_INFO "%s: tun_chr_ioctl cmd %d\n", tun->dev->name, cmd);
592 
593 	switch (cmd) {
594 	case TUNSETNOCSUM:
595 		/* Disable/Enable checksum */
596 		if (arg)
597 			tun->flags |= TUN_NOCHECKSUM;
598 		else
599 			tun->flags &= ~TUN_NOCHECKSUM;
600 
601 		DBG(KERN_INFO "%s: checksum %s\n",
602 		    tun->dev->name, arg ? "disabled" : "enabled");
603 		break;
604 
605 	case TUNSETPERSIST:
606 		/* Disable/Enable persist mode */
607 		if (arg)
608 			tun->flags |= TUN_PERSIST;
609 		else
610 			tun->flags &= ~TUN_PERSIST;
611 
612 		DBG(KERN_INFO "%s: persist %s\n",
613 		    tun->dev->name, arg ? "disabled" : "enabled");
614 		break;
615 
616 	case TUNSETOWNER:
617 		/* Set owner of the device */
618 		tun->owner = (uid_t) arg;
619 
620 		DBG(KERN_INFO "%s: owner set to %d\n", tun->dev->name, tun->owner);
621 		break;
622 
623 	case TUNSETLINK:
624 		/* Only allow setting the type when the interface is down */
625 		if (tun->dev->flags & IFF_UP) {
626 			DBG(KERN_INFO "%s: Linktype set failed because interface is up\n",
627 				tun->dev->name);
628 			return -EBUSY;
629 		} else {
630 			tun->dev->type = (int) arg;
631 			DBG(KERN_INFO "%s: linktype set to %d\n", tun->dev->name, tun->dev->type);
632 		}
633 		break;
634 
635 #ifdef TUN_DEBUG
636 	case TUNSETDEBUG:
637 		tun->debug = arg;
638 		break;
639 #endif
640 
641 	case SIOCGIFFLAGS:
642 		ifr.ifr_flags = tun->if_flags;
643 		if (copy_to_user( argp, &ifr, sizeof ifr))
644 			return -EFAULT;
645 		return 0;
646 
647 	case SIOCSIFFLAGS:
648 		/** Set the character device's interface flags. Currently only
649 		 * IFF_PROMISC and IFF_ALLMULTI are used. */
650 		tun->if_flags = ifr.ifr_flags;
651 		DBG(KERN_INFO "%s: interface flags 0x%lx\n",
652 				tun->dev->name, tun->if_flags);
653 		return 0;
654 
655 	case SIOCGIFHWADDR:
656 		memcpy(ifr.ifr_hwaddr.sa_data, tun->dev_addr,
657 				min(sizeof ifr.ifr_hwaddr.sa_data, sizeof tun->dev_addr));
658 		if (copy_to_user( argp, &ifr, sizeof ifr))
659 			return -EFAULT;
660 		return 0;
661 
662 	case SIOCSIFHWADDR:
663 		/** Set the character device's hardware address. This is used when
664 		 * filtering packets being sent from the network device to the character
665 		 * device. */
666 		memcpy(tun->dev_addr, ifr.ifr_hwaddr.sa_data,
667 				min(sizeof ifr.ifr_hwaddr.sa_data, sizeof tun->dev_addr));
668 		DBG(KERN_DEBUG "%s: set hardware address: %x:%x:%x:%x:%x:%x\n",
669 				tun->dev->name,
670 				tun->dev_addr[0], tun->dev_addr[1], tun->dev_addr[2],
671 				tun->dev_addr[3], tun->dev_addr[4], tun->dev_addr[5]);
672 		return 0;
673 
674 	case SIOCADDMULTI:
675 		/** Add the specified group to the character device's multicast filter
676 		 * list. */
677 		add_multi(tun->chr_filter, ifr.ifr_hwaddr.sa_data);
678 		DBG(KERN_DEBUG "%s: add multi: %x:%x:%x:%x:%x:%x\n",
679 				tun->dev->name,
680 				(u8)ifr.ifr_hwaddr.sa_data[0], (u8)ifr.ifr_hwaddr.sa_data[1],
681 				(u8)ifr.ifr_hwaddr.sa_data[2], (u8)ifr.ifr_hwaddr.sa_data[3],
682 				(u8)ifr.ifr_hwaddr.sa_data[4], (u8)ifr.ifr_hwaddr.sa_data[5]);
683 		return 0;
684 
685 	case SIOCDELMULTI:
686 		/** Remove the specified group from the character device's multicast
687 		 * filter list. */
688 		del_multi(tun->chr_filter, ifr.ifr_hwaddr.sa_data);
689 		DBG(KERN_DEBUG "%s: del multi: %x:%x:%x:%x:%x:%x\n",
690 				tun->dev->name,
691 				(u8)ifr.ifr_hwaddr.sa_data[0], (u8)ifr.ifr_hwaddr.sa_data[1],
692 				(u8)ifr.ifr_hwaddr.sa_data[2], (u8)ifr.ifr_hwaddr.sa_data[3],
693 				(u8)ifr.ifr_hwaddr.sa_data[4], (u8)ifr.ifr_hwaddr.sa_data[5]);
694 		return 0;
695 
696 	default:
697 		return -EINVAL;
698 	};
699 
700 	return 0;
701 }
702 
703 static int tun_chr_fasync(int fd, struct file *file, int on)
704 {
705 	struct tun_struct *tun = file->private_data;
706 	int ret;
707 
708 	if (!tun)
709 		return -EBADFD;
710 
711 	DBG(KERN_INFO "%s: tun_chr_fasync %d\n", tun->dev->name, on);
712 
713 	if ((ret = fasync_helper(fd, file, on, &tun->fasync)) < 0)
714 		return ret;
715 
716 	if (on) {
717 		ret = f_setown(file, current->pid, 0);
718 		if (ret)
719 			return ret;
720 		tun->flags |= TUN_FASYNC;
721 	} else
722 		tun->flags &= ~TUN_FASYNC;
723 
724 	return 0;
725 }
726 
727 static int tun_chr_open(struct inode *inode, struct file * file)
728 {
729 	DBG1(KERN_INFO "tunX: tun_chr_open\n");
730 	file->private_data = NULL;
731 	return 0;
732 }
733 
734 static int tun_chr_close(struct inode *inode, struct file *file)
735 {
736 	struct tun_struct *tun = file->private_data;
737 
738 	if (!tun)
739 		return 0;
740 
741 	DBG(KERN_INFO "%s: tun_chr_close\n", tun->dev->name);
742 
743 	tun_chr_fasync(-1, file, 0);
744 
745 	rtnl_lock();
746 
747 	/* Detach from net device */
748 	file->private_data = NULL;
749 	tun->attached = 0;
750 
751 	/* Drop read queue */
752 	skb_queue_purge(&tun->readq);
753 
754 	if (!(tun->flags & TUN_PERSIST)) {
755 		list_del(&tun->list);
756 		unregister_netdevice(tun->dev);
757 	}
758 
759 	rtnl_unlock();
760 
761 	return 0;
762 }
763 
764 static struct file_operations tun_fops = {
765 	.owner	= THIS_MODULE,
766 	.llseek = no_llseek,
767 	.read	= tun_chr_read,
768 	.readv	= tun_chr_readv,
769 	.write	= tun_chr_write,
770 	.writev = tun_chr_writev,
771 	.poll	= tun_chr_poll,
772 	.ioctl	= tun_chr_ioctl,
773 	.open	= tun_chr_open,
774 	.release = tun_chr_close,
775 	.fasync = tun_chr_fasync
776 };
777 
778 static struct miscdevice tun_miscdev = {
779 	.minor = TUN_MINOR,
780 	.name = "tun",
781 	.fops = &tun_fops,
782 };
783 
784 /* ethtool interface */
785 
786 static int tun_get_settings(struct net_device *dev, struct ethtool_cmd *cmd)
787 {
788 	cmd->supported		= 0;
789 	cmd->advertising	= 0;
790 	cmd->speed		= SPEED_10;
791 	cmd->duplex		= DUPLEX_FULL;
792 	cmd->port		= PORT_TP;
793 	cmd->phy_address	= 0;
794 	cmd->transceiver	= XCVR_INTERNAL;
795 	cmd->autoneg		= AUTONEG_DISABLE;
796 	cmd->maxtxpkt		= 0;
797 	cmd->maxrxpkt		= 0;
798 	return 0;
799 }
800 
801 static void tun_get_drvinfo(struct net_device *dev, struct ethtool_drvinfo *info)
802 {
803 	struct tun_struct *tun = netdev_priv(dev);
804 
805 	strcpy(info->driver, DRV_NAME);
806 	strcpy(info->version, DRV_VERSION);
807 	strcpy(info->fw_version, "N/A");
808 
809 	switch (tun->flags & TUN_TYPE_MASK) {
810 	case TUN_TUN_DEV:
811 		strcpy(info->bus_info, "tun");
812 		break;
813 	case TUN_TAP_DEV:
814 		strcpy(info->bus_info, "tap");
815 		break;
816 	}
817 }
818 
819 static u32 tun_get_msglevel(struct net_device *dev)
820 {
821 #ifdef TUN_DEBUG
822 	struct tun_struct *tun = netdev_priv(dev);
823 	return tun->debug;
824 #else
825 	return -EOPNOTSUPP;
826 #endif
827 }
828 
829 static void tun_set_msglevel(struct net_device *dev, u32 value)
830 {
831 #ifdef TUN_DEBUG
832 	struct tun_struct *tun = netdev_priv(dev);
833 	tun->debug = value;
834 #endif
835 }
836 
837 static u32 tun_get_link(struct net_device *dev)
838 {
839 	struct tun_struct *tun = netdev_priv(dev);
840 	return tun->attached;
841 }
842 
843 static u32 tun_get_rx_csum(struct net_device *dev)
844 {
845 	struct tun_struct *tun = netdev_priv(dev);
846 	return (tun->flags & TUN_NOCHECKSUM) == 0;
847 }
848 
849 static int tun_set_rx_csum(struct net_device *dev, u32 data)
850 {
851 	struct tun_struct *tun = netdev_priv(dev);
852 	if (data)
853 		tun->flags &= ~TUN_NOCHECKSUM;
854 	else
855 		tun->flags |= TUN_NOCHECKSUM;
856 	return 0;
857 }
858 
859 static struct ethtool_ops tun_ethtool_ops = {
860 	.get_settings	= tun_get_settings,
861 	.get_drvinfo	= tun_get_drvinfo,
862 	.get_msglevel	= tun_get_msglevel,
863 	.set_msglevel	= tun_set_msglevel,
864 	.get_link	= tun_get_link,
865 	.get_rx_csum	= tun_get_rx_csum,
866 	.set_rx_csum	= tun_set_rx_csum
867 };
868 
869 static int __init tun_init(void)
870 {
871 	int ret = 0;
872 
873 	printk(KERN_INFO "tun: %s, %s\n", DRV_DESCRIPTION, DRV_VERSION);
874 	printk(KERN_INFO "tun: %s\n", DRV_COPYRIGHT);
875 
876 	ret = misc_register(&tun_miscdev);
877 	if (ret)
878 		printk(KERN_ERR "tun: Can't register misc device %d\n", TUN_MINOR);
879 	return ret;
880 }
881 
882 static void tun_cleanup(void)
883 {
884 	struct tun_struct *tun, *nxt;
885 
886 	misc_deregister(&tun_miscdev);
887 
888 	rtnl_lock();
889 	list_for_each_entry_safe(tun, nxt, &tun_dev_list, list) {
890 		DBG(KERN_INFO "%s cleaned up\n", tun->dev->name);
891 		unregister_netdevice(tun->dev);
892 	}
893 	rtnl_unlock();
894 
895 }
896 
897 module_init(tun_init);
898 module_exit(tun_cleanup);
899 MODULE_DESCRIPTION(DRV_DESCRIPTION);
900 MODULE_AUTHOR(DRV_COPYRIGHT);
901 MODULE_LICENSE("GPL");
902 MODULE_ALIAS_MISCDEV(TUN_MINOR);
903