xref: /openbmc/linux/drivers/net/tun.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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/config.h>
43 #include <linux/module.h>
44 #include <linux/errno.h>
45 #include <linux/kernel.h>
46 #include <linux/major.h>
47 #include <linux/slab.h>
48 #include <linux/poll.h>
49 #include <linux/fcntl.h>
50 #include <linux/init.h>
51 #include <linux/skbuff.h>
52 #include <linux/netdevice.h>
53 #include <linux/etherdevice.h>
54 #include <linux/miscdevice.h>
55 #include <linux/ethtool.h>
56 #include <linux/rtnetlink.h>
57 #include <linux/if.h>
58 #include <linux/if_arp.h>
59 #include <linux/if_ether.h>
60 #include <linux/if_tun.h>
61 #include <linux/crc32.h>
62 
63 #include <asm/system.h>
64 #include <asm/uaccess.h>
65 
66 #ifdef TUN_DEBUG
67 static int debug;
68 #endif
69 
70 /* Network device part of the driver */
71 
72 static LIST_HEAD(tun_dev_list);
73 static struct ethtool_ops tun_ethtool_ops;
74 
75 /* Net device open. */
76 static int tun_net_open(struct net_device *dev)
77 {
78 	netif_start_queue(dev);
79 	return 0;
80 }
81 
82 /* Net device close. */
83 static int tun_net_close(struct net_device *dev)
84 {
85 	netif_stop_queue(dev);
86 	return 0;
87 }
88 
89 /* Net device start xmit */
90 static int tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
91 {
92 	struct tun_struct *tun = netdev_priv(dev);
93 
94 	DBG(KERN_INFO "%s: tun_net_xmit %d\n", tun->dev->name, skb->len);
95 
96 	/* Drop packet if interface is not attached */
97 	if (!tun->attached)
98 		goto drop;
99 
100 	/* Packet dropping */
101 	if (skb_queue_len(&tun->readq) >= dev->tx_queue_len) {
102 		if (!(tun->flags & TUN_ONE_QUEUE)) {
103 			/* Normal queueing mode. */
104 			/* Packet scheduler handles dropping of further packets. */
105 			netif_stop_queue(dev);
106 
107 			/* We won't see all dropped packets individually, so overrun
108 			 * error is more appropriate. */
109 			tun->stats.tx_fifo_errors++;
110 		} else {
111 			/* Single queue mode.
112 			 * Driver handles dropping of all packets itself. */
113 			goto drop;
114 		}
115 	}
116 
117 	/* Queue packet */
118 	skb_queue_tail(&tun->readq, skb);
119 	dev->trans_start = jiffies;
120 
121 	/* Notify and wake up reader process */
122 	if (tun->flags & TUN_FASYNC)
123 		kill_fasync(&tun->fasync, SIGIO, POLL_IN);
124 	wake_up_interruptible(&tun->read_wait);
125 	return 0;
126 
127 drop:
128 	tun->stats.tx_dropped++;
129 	kfree_skb(skb);
130 	return 0;
131 }
132 
133 /** Add the specified Ethernet address to this multicast filter. */
134 static void
135 add_multi(u32* filter, const u8* addr)
136 {
137 	int bit_nr = ether_crc(ETH_ALEN, addr) >> 26;
138 	filter[bit_nr >> 5] |= 1 << (bit_nr & 31);
139 }
140 
141 /** Remove the specified Ethernet addres from this multicast filter. */
142 static void
143 del_multi(u32* filter, const u8* addr)
144 {
145 	int bit_nr = ether_crc(ETH_ALEN, addr) >> 26;
146 	filter[bit_nr >> 5] &= ~(1 << (bit_nr & 31));
147 }
148 
149 /** Update the list of multicast groups to which the network device belongs.
150  * This list is used to filter packets being sent from the character device to
151  * the network device. */
152 static void
153 tun_net_mclist(struct net_device *dev)
154 {
155 	struct tun_struct *tun = netdev_priv(dev);
156 	const struct dev_mc_list *mclist;
157 	int i;
158 	DBG(KERN_DEBUG "%s: tun_net_mclist: mc_count %d\n",
159 			dev->name, dev->mc_count);
160 	memset(tun->chr_filter, 0, sizeof tun->chr_filter);
161 	for (i = 0, mclist = dev->mc_list; i < dev->mc_count && mclist != NULL;
162 			i++, mclist = mclist->next) {
163 		add_multi(tun->net_filter, mclist->dmi_addr);
164 		DBG(KERN_DEBUG "%s: tun_net_mclist: %x:%x:%x:%x:%x:%x\n",
165 				dev->name,
166 				mclist->dmi_addr[0], mclist->dmi_addr[1], mclist->dmi_addr[2],
167 				mclist->dmi_addr[3], mclist->dmi_addr[4], mclist->dmi_addr[5]);
168 	}
169 }
170 
171 static struct net_device_stats *tun_net_stats(struct net_device *dev)
172 {
173 	struct tun_struct *tun = netdev_priv(dev);
174 	return &tun->stats;
175 }
176 
177 /* Initialize net device. */
178 static void tun_net_init(struct net_device *dev)
179 {
180 	struct tun_struct *tun = netdev_priv(dev);
181 
182 	switch (tun->flags & TUN_TYPE_MASK) {
183 	case TUN_TUN_DEV:
184 		/* Point-to-Point TUN Device */
185 		dev->hard_header_len = 0;
186 		dev->addr_len = 0;
187 		dev->mtu = 1500;
188 
189 		/* Zero header length */
190 		dev->type = ARPHRD_NONE;
191 		dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
192 		dev->tx_queue_len = TUN_READQ_SIZE;  /* We prefer our own queue length */
193 		break;
194 
195 	case TUN_TAP_DEV:
196 		/* Ethernet TAP Device */
197 		dev->set_multicast_list = tun_net_mclist;
198 
199 		ether_setup(dev);
200 		random_ether_addr(dev->dev_addr);
201 		dev->tx_queue_len = TUN_READQ_SIZE;  /* We prefer our own queue length */
202 		break;
203 	}
204 }
205 
206 /* Character device part */
207 
208 /* Poll */
209 static unsigned int tun_chr_poll(struct file *file, poll_table * wait)
210 {
211 	struct tun_struct *tun = file->private_data;
212 	unsigned int mask = POLLOUT | POLLWRNORM;
213 
214 	if (!tun)
215 		return -EBADFD;
216 
217 	DBG(KERN_INFO "%s: tun_chr_poll\n", tun->dev->name);
218 
219 	poll_wait(file, &tun->read_wait, wait);
220 
221 	if (!skb_queue_empty(&tun->readq))
222 		mask |= POLLIN | POLLRDNORM;
223 
224 	return mask;
225 }
226 
227 /* Get packet from user space buffer */
228 static __inline__ ssize_t tun_get_user(struct tun_struct *tun, struct iovec *iv, size_t count)
229 {
230 	struct tun_pi pi = { 0, __constant_htons(ETH_P_IP) };
231 	struct sk_buff *skb;
232 	size_t len = count, align = 0;
233 
234 	if (!(tun->flags & TUN_NO_PI)) {
235 		if ((len -= sizeof(pi)) > count)
236 			return -EINVAL;
237 
238 		if(memcpy_fromiovec((void *)&pi, iv, sizeof(pi)))
239 			return -EFAULT;
240 	}
241 
242 	if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV)
243 		align = NET_IP_ALIGN;
244 
245 	if (!(skb = alloc_skb(len + align, GFP_KERNEL))) {
246 		tun->stats.rx_dropped++;
247 		return -ENOMEM;
248 	}
249 
250 	if (align)
251 		skb_reserve(skb, align);
252 	if (memcpy_fromiovec(skb_put(skb, len), iv, len))
253 		return -EFAULT;
254 
255 	skb->dev = tun->dev;
256 	switch (tun->flags & TUN_TYPE_MASK) {
257 	case TUN_TUN_DEV:
258 		skb->mac.raw = skb->data;
259 		skb->protocol = pi.proto;
260 		break;
261 	case TUN_TAP_DEV:
262 		skb->protocol = eth_type_trans(skb, tun->dev);
263 		break;
264 	};
265 
266 	if (tun->flags & TUN_NOCHECKSUM)
267 		skb->ip_summed = CHECKSUM_UNNECESSARY;
268 
269 	netif_rx_ni(skb);
270 	tun->dev->last_rx = jiffies;
271 
272 	tun->stats.rx_packets++;
273 	tun->stats.rx_bytes += len;
274 
275 	return count;
276 }
277 
278 static inline size_t iov_total(const struct iovec *iv, unsigned long count)
279 {
280 	unsigned long i;
281 	size_t len;
282 
283 	for (i = 0, len = 0; i < count; i++)
284 		len += iv[i].iov_len;
285 
286 	return len;
287 }
288 
289 /* Writev */
290 static ssize_t tun_chr_writev(struct file * file, const struct iovec *iv,
291 			      unsigned long count, loff_t *pos)
292 {
293 	struct tun_struct *tun = file->private_data;
294 
295 	if (!tun)
296 		return -EBADFD;
297 
298 	DBG(KERN_INFO "%s: tun_chr_write %ld\n", tun->dev->name, count);
299 
300 	return tun_get_user(tun, (struct iovec *) iv, iov_total(iv, count));
301 }
302 
303 /* Write */
304 static ssize_t tun_chr_write(struct file * file, const char __user * buf,
305 			     size_t count, loff_t *pos)
306 {
307 	struct iovec iv = { (void __user *) buf, count };
308 	return tun_chr_writev(file, &iv, 1, pos);
309 }
310 
311 /* Put packet to the user space buffer */
312 static __inline__ ssize_t tun_put_user(struct tun_struct *tun,
313 				       struct sk_buff *skb,
314 				       struct iovec *iv, int len)
315 {
316 	struct tun_pi pi = { 0, skb->protocol };
317 	ssize_t total = 0;
318 
319 	if (!(tun->flags & TUN_NO_PI)) {
320 		if ((len -= sizeof(pi)) < 0)
321 			return -EINVAL;
322 
323 		if (len < skb->len) {
324 			/* Packet will be striped */
325 			pi.flags |= TUN_PKT_STRIP;
326 		}
327 
328 		if (memcpy_toiovec(iv, (void *) &pi, sizeof(pi)))
329 			return -EFAULT;
330 		total += sizeof(pi);
331 	}
332 
333 	len = min_t(int, skb->len, len);
334 
335 	skb_copy_datagram_iovec(skb, 0, iv, len);
336 	total += len;
337 
338 	tun->stats.tx_packets++;
339 	tun->stats.tx_bytes += len;
340 
341 	return total;
342 }
343 
344 /* Readv */
345 static ssize_t tun_chr_readv(struct file *file, const struct iovec *iv,
346 			    unsigned long count, loff_t *pos)
347 {
348 	struct tun_struct *tun = file->private_data;
349 	DECLARE_WAITQUEUE(wait, current);
350 	struct sk_buff *skb;
351 	ssize_t len, ret = 0;
352 
353 	if (!tun)
354 		return -EBADFD;
355 
356 	DBG(KERN_INFO "%s: tun_chr_read\n", tun->dev->name);
357 
358 	len = iov_total(iv, count);
359 	if (len < 0)
360 		return -EINVAL;
361 
362 	add_wait_queue(&tun->read_wait, &wait);
363 	while (len) {
364 		const u8 ones[ ETH_ALEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
365 		u8 addr[ ETH_ALEN];
366 		int bit_nr;
367 
368 		current->state = TASK_INTERRUPTIBLE;
369 
370 		/* Read frames from the queue */
371 		if (!(skb=skb_dequeue(&tun->readq))) {
372 			if (file->f_flags & O_NONBLOCK) {
373 				ret = -EAGAIN;
374 				break;
375 			}
376 			if (signal_pending(current)) {
377 				ret = -ERESTARTSYS;
378 				break;
379 			}
380 
381 			/* Nothing to read, let's sleep */
382 			schedule();
383 			continue;
384 		}
385 		netif_wake_queue(tun->dev);
386 
387 		/** Decide whether to accept this packet. This code is designed to
388 		 * behave identically to an Ethernet interface. Accept the packet if
389 		 * - we are promiscuous.
390 		 * - the packet is addressed to us.
391 		 * - the packet is broadcast.
392 		 * - the packet is multicast and
393 		 *   - we are multicast promiscous.
394 		 *   - we belong to the multicast group.
395 		 */
396 		memcpy(addr, skb->data,
397 		       min_t(size_t, sizeof addr, skb->len));
398 		bit_nr = ether_crc(sizeof addr, addr) >> 26;
399 		if ((tun->if_flags & IFF_PROMISC) ||
400 				memcmp(addr, tun->dev_addr, sizeof addr) == 0 ||
401 				memcmp(addr, ones, sizeof addr) == 0 ||
402 				(((addr[0] == 1 && addr[1] == 0 && addr[2] == 0x5e) ||
403 				  (addr[0] == 0x33 && addr[1] == 0x33)) &&
404 				 ((tun->if_flags & IFF_ALLMULTI) ||
405 				  (tun->chr_filter[bit_nr >> 5] & (1 << (bit_nr & 31)))))) {
406 			DBG(KERN_DEBUG "%s: tun_chr_readv: accepted: %x:%x:%x:%x:%x:%x\n",
407 					tun->dev->name, addr[0], addr[1], addr[2],
408 					addr[3], addr[4], addr[5]);
409 			ret = tun_put_user(tun, skb, (struct iovec *) iv, len);
410 			kfree_skb(skb);
411 			break;
412 		} else {
413 			DBG(KERN_DEBUG "%s: tun_chr_readv: rejected: %x:%x:%x:%x:%x:%x\n",
414 					tun->dev->name, addr[0], addr[1], addr[2],
415 					addr[3], addr[4], addr[5]);
416 			kfree_skb(skb);
417 			continue;
418 		}
419 	}
420 
421 	current->state = TASK_RUNNING;
422 	remove_wait_queue(&tun->read_wait, &wait);
423 
424 	return ret;
425 }
426 
427 /* Read */
428 static ssize_t tun_chr_read(struct file * file, char __user * buf,
429 			    size_t count, loff_t *pos)
430 {
431 	struct iovec iv = { buf, count };
432 	return tun_chr_readv(file, &iv, 1, pos);
433 }
434 
435 static void tun_setup(struct net_device *dev)
436 {
437 	struct tun_struct *tun = netdev_priv(dev);
438 
439 	skb_queue_head_init(&tun->readq);
440 	init_waitqueue_head(&tun->read_wait);
441 
442 	tun->owner = -1;
443 
444 	SET_MODULE_OWNER(dev);
445 	dev->open = tun_net_open;
446 	dev->hard_start_xmit = tun_net_xmit;
447 	dev->stop = tun_net_close;
448 	dev->get_stats = tun_net_stats;
449 	dev->ethtool_ops = &tun_ethtool_ops;
450 	dev->destructor = free_netdev;
451 }
452 
453 static struct tun_struct *tun_get_by_name(const char *name)
454 {
455 	struct tun_struct *tun;
456 
457 	ASSERT_RTNL();
458 	list_for_each_entry(tun, &tun_dev_list, list) {
459 		if (!strncmp(tun->dev->name, name, IFNAMSIZ))
460 		    return tun;
461 	}
462 
463 	return NULL;
464 }
465 
466 static int tun_set_iff(struct file *file, struct ifreq *ifr)
467 {
468 	struct tun_struct *tun;
469 	struct net_device *dev;
470 	int err;
471 
472 	tun = tun_get_by_name(ifr->ifr_name);
473 	if (tun) {
474 		if (tun->attached)
475 			return -EBUSY;
476 
477 		/* Check permissions */
478 		if (tun->owner != -1 &&
479 		    current->euid != tun->owner && !capable(CAP_NET_ADMIN))
480 			return -EPERM;
481 	}
482 	else if (__dev_get_by_name(ifr->ifr_name))
483 		return -EINVAL;
484 	else {
485 		char *name;
486 		unsigned long flags = 0;
487 
488 		err = -EINVAL;
489 
490 		/* Set dev type */
491 		if (ifr->ifr_flags & IFF_TUN) {
492 			/* TUN device */
493 			flags |= TUN_TUN_DEV;
494 			name = "tun%d";
495 		} else if (ifr->ifr_flags & IFF_TAP) {
496 			/* TAP device */
497 			flags |= TUN_TAP_DEV;
498 			name = "tap%d";
499 		} else
500 			goto failed;
501 
502 		if (*ifr->ifr_name)
503 			name = ifr->ifr_name;
504 
505 		dev = alloc_netdev(sizeof(struct tun_struct), name,
506 				   tun_setup);
507 		if (!dev)
508 			return -ENOMEM;
509 
510 		tun = netdev_priv(dev);
511 		tun->dev = dev;
512 		tun->flags = flags;
513 		/* Be promiscuous by default to maintain previous behaviour. */
514 		tun->if_flags = IFF_PROMISC;
515 		/* Generate random Ethernet address. */
516 		*(u16 *)tun->dev_addr = htons(0x00FF);
517 		get_random_bytes(tun->dev_addr + sizeof(u16), 4);
518 		memset(tun->chr_filter, 0, sizeof tun->chr_filter);
519 
520 		tun_net_init(dev);
521 
522 		if (strchr(dev->name, '%')) {
523 			err = dev_alloc_name(dev, dev->name);
524 			if (err < 0)
525 				goto err_free_dev;
526 		}
527 
528 		err = register_netdevice(tun->dev);
529 		if (err < 0)
530 			goto err_free_dev;
531 
532 		list_add(&tun->list, &tun_dev_list);
533 	}
534 
535 	DBG(KERN_INFO "%s: tun_set_iff\n", tun->dev->name);
536 
537 	if (ifr->ifr_flags & IFF_NO_PI)
538 		tun->flags |= TUN_NO_PI;
539 
540 	if (ifr->ifr_flags & IFF_ONE_QUEUE)
541 		tun->flags |= TUN_ONE_QUEUE;
542 
543 	file->private_data = tun;
544 	tun->attached = 1;
545 
546 	strcpy(ifr->ifr_name, tun->dev->name);
547 	return 0;
548 
549  err_free_dev:
550 	free_netdev(dev);
551  failed:
552 	return err;
553 }
554 
555 static int tun_chr_ioctl(struct inode *inode, struct file *file,
556 			 unsigned int cmd, unsigned long arg)
557 {
558 	struct tun_struct *tun = file->private_data;
559 	void __user* argp = (void __user*)arg;
560 	struct ifreq ifr;
561 
562 	if (cmd == TUNSETIFF || _IOC_TYPE(cmd) == 0x89)
563 		if (copy_from_user(&ifr, argp, sizeof ifr))
564 			return -EFAULT;
565 
566 	if (cmd == TUNSETIFF && !tun) {
567 		int err;
568 
569 		ifr.ifr_name[IFNAMSIZ-1] = '\0';
570 
571 		rtnl_lock();
572 		err = tun_set_iff(file, &ifr);
573 		rtnl_unlock();
574 
575 		if (err)
576 			return err;
577 
578 		if (copy_to_user(argp, &ifr, sizeof(ifr)))
579 			return -EFAULT;
580 		return 0;
581 	}
582 
583 	if (!tun)
584 		return -EBADFD;
585 
586 	DBG(KERN_INFO "%s: tun_chr_ioctl cmd %d\n", tun->dev->name, cmd);
587 
588 	switch (cmd) {
589 	case TUNSETNOCSUM:
590 		/* Disable/Enable checksum */
591 		if (arg)
592 			tun->flags |= TUN_NOCHECKSUM;
593 		else
594 			tun->flags &= ~TUN_NOCHECKSUM;
595 
596 		DBG(KERN_INFO "%s: checksum %s\n",
597 		    tun->dev->name, arg ? "disabled" : "enabled");
598 		break;
599 
600 	case TUNSETPERSIST:
601 		/* Disable/Enable persist mode */
602 		if (arg)
603 			tun->flags |= TUN_PERSIST;
604 		else
605 			tun->flags &= ~TUN_PERSIST;
606 
607 		DBG(KERN_INFO "%s: persist %s\n",
608 		    tun->dev->name, arg ? "disabled" : "enabled");
609 		break;
610 
611 	case TUNSETOWNER:
612 		/* Set owner of the device */
613 		tun->owner = (uid_t) arg;
614 
615 		DBG(KERN_INFO "%s: owner set to %d\n", tun->dev->name, tun->owner);
616 		break;
617 
618 	case TUNSETLINK:
619 		/* Only allow setting the type when the interface is down */
620 		if (tun->dev->flags & IFF_UP) {
621 			DBG(KERN_INFO "%s: Linktype set failed because interface is up\n",
622 				tun->dev->name);
623 			return -EBUSY;
624 		} else {
625 			tun->dev->type = (int) arg;
626 			DBG(KERN_INFO "%s: linktype set to %d\n", tun->dev->name, tun->dev->type);
627 		}
628 		break;
629 
630 #ifdef TUN_DEBUG
631 	case TUNSETDEBUG:
632 		tun->debug = arg;
633 		break;
634 #endif
635 
636 	case SIOCGIFFLAGS:
637 		ifr.ifr_flags = tun->if_flags;
638 		if (copy_to_user( argp, &ifr, sizeof ifr))
639 			return -EFAULT;
640 		return 0;
641 
642 	case SIOCSIFFLAGS:
643 		/** Set the character device's interface flags. Currently only
644 		 * IFF_PROMISC and IFF_ALLMULTI are used. */
645 		tun->if_flags = ifr.ifr_flags;
646 		DBG(KERN_INFO "%s: interface flags 0x%lx\n",
647 				tun->dev->name, tun->if_flags);
648 		return 0;
649 
650 	case SIOCGIFHWADDR:
651 		memcpy(ifr.ifr_hwaddr.sa_data, tun->dev_addr,
652 				min(sizeof ifr.ifr_hwaddr.sa_data, sizeof tun->dev_addr));
653 		if (copy_to_user( argp, &ifr, sizeof ifr))
654 			return -EFAULT;
655 		return 0;
656 
657 	case SIOCSIFHWADDR:
658 		/** Set the character device's hardware address. This is used when
659 		 * filtering packets being sent from the network device to the character
660 		 * device. */
661 		memcpy(tun->dev_addr, ifr.ifr_hwaddr.sa_data,
662 				min(sizeof ifr.ifr_hwaddr.sa_data, sizeof tun->dev_addr));
663 		DBG(KERN_DEBUG "%s: set hardware address: %x:%x:%x:%x:%x:%x\n",
664 				tun->dev->name,
665 				tun->dev_addr[0], tun->dev_addr[1], tun->dev_addr[2],
666 				tun->dev_addr[3], tun->dev_addr[4], tun->dev_addr[5]);
667 		return 0;
668 
669 	case SIOCADDMULTI:
670 		/** Add the specified group to the character device's multicast filter
671 		 * list. */
672 		add_multi(tun->chr_filter, ifr.ifr_hwaddr.sa_data);
673 		DBG(KERN_DEBUG "%s: add multi: %x:%x:%x:%x:%x:%x\n",
674 				tun->dev->name,
675 				(u8)ifr.ifr_hwaddr.sa_data[0], (u8)ifr.ifr_hwaddr.sa_data[1],
676 				(u8)ifr.ifr_hwaddr.sa_data[2], (u8)ifr.ifr_hwaddr.sa_data[3],
677 				(u8)ifr.ifr_hwaddr.sa_data[4], (u8)ifr.ifr_hwaddr.sa_data[5]);
678 		return 0;
679 
680 	case SIOCDELMULTI:
681 		/** Remove the specified group from the character device's multicast
682 		 * filter list. */
683 		del_multi(tun->chr_filter, ifr.ifr_hwaddr.sa_data);
684 		DBG(KERN_DEBUG "%s: del multi: %x:%x:%x:%x:%x:%x\n",
685 				tun->dev->name,
686 				(u8)ifr.ifr_hwaddr.sa_data[0], (u8)ifr.ifr_hwaddr.sa_data[1],
687 				(u8)ifr.ifr_hwaddr.sa_data[2], (u8)ifr.ifr_hwaddr.sa_data[3],
688 				(u8)ifr.ifr_hwaddr.sa_data[4], (u8)ifr.ifr_hwaddr.sa_data[5]);
689 		return 0;
690 
691 	default:
692 		return -EINVAL;
693 	};
694 
695 	return 0;
696 }
697 
698 static int tun_chr_fasync(int fd, struct file *file, int on)
699 {
700 	struct tun_struct *tun = file->private_data;
701 	int ret;
702 
703 	if (!tun)
704 		return -EBADFD;
705 
706 	DBG(KERN_INFO "%s: tun_chr_fasync %d\n", tun->dev->name, on);
707 
708 	if ((ret = fasync_helper(fd, file, on, &tun->fasync)) < 0)
709 		return ret;
710 
711 	if (on) {
712 		ret = f_setown(file, current->pid, 0);
713 		if (ret)
714 			return ret;
715 		tun->flags |= TUN_FASYNC;
716 	} else
717 		tun->flags &= ~TUN_FASYNC;
718 
719 	return 0;
720 }
721 
722 static int tun_chr_open(struct inode *inode, struct file * file)
723 {
724 	DBG1(KERN_INFO "tunX: tun_chr_open\n");
725 	file->private_data = NULL;
726 	return 0;
727 }
728 
729 static int tun_chr_close(struct inode *inode, struct file *file)
730 {
731 	struct tun_struct *tun = file->private_data;
732 
733 	if (!tun)
734 		return 0;
735 
736 	DBG(KERN_INFO "%s: tun_chr_close\n", tun->dev->name);
737 
738 	tun_chr_fasync(-1, file, 0);
739 
740 	rtnl_lock();
741 
742 	/* Detach from net device */
743 	file->private_data = NULL;
744 	tun->attached = 0;
745 
746 	/* Drop read queue */
747 	skb_queue_purge(&tun->readq);
748 
749 	if (!(tun->flags & TUN_PERSIST)) {
750 		list_del(&tun->list);
751 		unregister_netdevice(tun->dev);
752 	}
753 
754 	rtnl_unlock();
755 
756 	return 0;
757 }
758 
759 static struct file_operations tun_fops = {
760 	.owner	= THIS_MODULE,
761 	.llseek = no_llseek,
762 	.read	= tun_chr_read,
763 	.readv	= tun_chr_readv,
764 	.write	= tun_chr_write,
765 	.writev = tun_chr_writev,
766 	.poll	= tun_chr_poll,
767 	.ioctl	= tun_chr_ioctl,
768 	.open	= tun_chr_open,
769 	.release = tun_chr_close,
770 	.fasync = tun_chr_fasync
771 };
772 
773 static struct miscdevice tun_miscdev = {
774 	.minor = TUN_MINOR,
775 	.name = "tun",
776 	.fops = &tun_fops,
777 	.devfs_name = "net/tun",
778 };
779 
780 /* ethtool interface */
781 
782 static int tun_get_settings(struct net_device *dev, struct ethtool_cmd *cmd)
783 {
784 	cmd->supported		= 0;
785 	cmd->advertising	= 0;
786 	cmd->speed		= SPEED_10;
787 	cmd->duplex		= DUPLEX_FULL;
788 	cmd->port		= PORT_TP;
789 	cmd->phy_address	= 0;
790 	cmd->transceiver	= XCVR_INTERNAL;
791 	cmd->autoneg		= AUTONEG_DISABLE;
792 	cmd->maxtxpkt		= 0;
793 	cmd->maxrxpkt		= 0;
794 	return 0;
795 }
796 
797 static void tun_get_drvinfo(struct net_device *dev, struct ethtool_drvinfo *info)
798 {
799 	struct tun_struct *tun = netdev_priv(dev);
800 
801 	strcpy(info->driver, DRV_NAME);
802 	strcpy(info->version, DRV_VERSION);
803 	strcpy(info->fw_version, "N/A");
804 
805 	switch (tun->flags & TUN_TYPE_MASK) {
806 	case TUN_TUN_DEV:
807 		strcpy(info->bus_info, "tun");
808 		break;
809 	case TUN_TAP_DEV:
810 		strcpy(info->bus_info, "tap");
811 		break;
812 	}
813 }
814 
815 static u32 tun_get_msglevel(struct net_device *dev)
816 {
817 #ifdef TUN_DEBUG
818 	struct tun_struct *tun = netdev_priv(dev);
819 	return tun->debug;
820 #else
821 	return -EOPNOTSUPP;
822 #endif
823 }
824 
825 static void tun_set_msglevel(struct net_device *dev, u32 value)
826 {
827 #ifdef TUN_DEBUG
828 	struct tun_struct *tun = netdev_priv(dev);
829 	tun->debug = value;
830 #endif
831 }
832 
833 static u32 tun_get_link(struct net_device *dev)
834 {
835 	struct tun_struct *tun = netdev_priv(dev);
836 	return tun->attached;
837 }
838 
839 static u32 tun_get_rx_csum(struct net_device *dev)
840 {
841 	struct tun_struct *tun = netdev_priv(dev);
842 	return (tun->flags & TUN_NOCHECKSUM) == 0;
843 }
844 
845 static int tun_set_rx_csum(struct net_device *dev, u32 data)
846 {
847 	struct tun_struct *tun = netdev_priv(dev);
848 	if (data)
849 		tun->flags &= ~TUN_NOCHECKSUM;
850 	else
851 		tun->flags |= TUN_NOCHECKSUM;
852 	return 0;
853 }
854 
855 static struct ethtool_ops tun_ethtool_ops = {
856 	.get_settings	= tun_get_settings,
857 	.get_drvinfo	= tun_get_drvinfo,
858 	.get_msglevel	= tun_get_msglevel,
859 	.set_msglevel	= tun_set_msglevel,
860 	.get_link	= tun_get_link,
861 	.get_rx_csum	= tun_get_rx_csum,
862 	.set_rx_csum	= tun_set_rx_csum
863 };
864 
865 static int __init tun_init(void)
866 {
867 	int ret = 0;
868 
869 	printk(KERN_INFO "tun: %s, %s\n", DRV_DESCRIPTION, DRV_VERSION);
870 	printk(KERN_INFO "tun: %s\n", DRV_COPYRIGHT);
871 
872 	ret = misc_register(&tun_miscdev);
873 	if (ret)
874 		printk(KERN_ERR "tun: Can't register misc device %d\n", TUN_MINOR);
875 	return ret;
876 }
877 
878 static void tun_cleanup(void)
879 {
880 	struct tun_struct *tun, *nxt;
881 
882 	misc_deregister(&tun_miscdev);
883 
884 	rtnl_lock();
885 	list_for_each_entry_safe(tun, nxt, &tun_dev_list, list) {
886 		DBG(KERN_INFO "%s cleaned up\n", tun->dev->name);
887 		unregister_netdevice(tun->dev);
888 	}
889 	rtnl_unlock();
890 
891 }
892 
893 module_init(tun_init);
894 module_exit(tun_cleanup);
895 MODULE_DESCRIPTION(DRV_DESCRIPTION);
896 MODULE_AUTHOR(DRV_COPYRIGHT);
897 MODULE_LICENSE("GPL");
898 MODULE_ALIAS_MISCDEV(TUN_MINOR);
899