Version:  2.0.40 2.2.26 2.4.37 2.6.39 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15

Linux/drivers/net/tun.c

  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 eth_random_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 pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 38 
 39 #define DRV_NAME        "tun"
 40 #define DRV_VERSION     "1.6"
 41 #define DRV_DESCRIPTION "Universal TUN/TAP device driver"
 42 #define DRV_COPYRIGHT   "(C) 1999-2004 Max Krasnyansky <maxk@qualcomm.com>"
 43 
 44 #include <linux/module.h>
 45 #include <linux/errno.h>
 46 #include <linux/kernel.h>
 47 #include <linux/major.h>
 48 #include <linux/slab.h>
 49 #include <linux/poll.h>
 50 #include <linux/fcntl.h>
 51 #include <linux/init.h>
 52 #include <linux/skbuff.h>
 53 #include <linux/netdevice.h>
 54 #include <linux/etherdevice.h>
 55 #include <linux/miscdevice.h>
 56 #include <linux/ethtool.h>
 57 #include <linux/rtnetlink.h>
 58 #include <linux/compat.h>
 59 #include <linux/if.h>
 60 #include <linux/if_arp.h>
 61 #include <linux/if_ether.h>
 62 #include <linux/if_tun.h>
 63 #include <linux/if_vlan.h>
 64 #include <linux/crc32.h>
 65 #include <linux/nsproxy.h>
 66 #include <linux/virtio_net.h>
 67 #include <linux/rcupdate.h>
 68 #include <net/net_namespace.h>
 69 #include <net/netns/generic.h>
 70 #include <net/rtnetlink.h>
 71 #include <net/sock.h>
 72 #include <linux/seq_file.h>
 73 
 74 #include <asm/uaccess.h>
 75 
 76 /* Uncomment to enable debugging */
 77 /* #define TUN_DEBUG 1 */
 78 
 79 #ifdef TUN_DEBUG
 80 static int debug;
 81 
 82 #define tun_debug(level, tun, fmt, args...)                     \
 83 do {                                                            \
 84         if (tun->debug)                                         \
 85                 netdev_printk(level, tun->dev, fmt, ##args);    \
 86 } while (0)
 87 #define DBG1(level, fmt, args...)                               \
 88 do {                                                            \
 89         if (debug == 2)                                         \
 90                 printk(level fmt, ##args);                      \
 91 } while (0)
 92 #else
 93 #define tun_debug(level, tun, fmt, args...)                     \
 94 do {                                                            \
 95         if (0)                                                  \
 96                 netdev_printk(level, tun->dev, fmt, ##args);    \
 97 } while (0)
 98 #define DBG1(level, fmt, args...)                               \
 99 do {                                                            \
100         if (0)                                                  \
101                 printk(level fmt, ##args);                      \
102 } while (0)
103 #endif
104 
105 #define GOODCOPY_LEN 128
106 
107 #define FLT_EXACT_COUNT 8
108 struct tap_filter {
109         unsigned int    count;    /* Number of addrs. Zero means disabled */
110         u32             mask[2];  /* Mask of the hashed addrs */
111         unsigned char   addr[FLT_EXACT_COUNT][ETH_ALEN];
112 };
113 
114 /* DEFAULT_MAX_NUM_RSS_QUEUES were chosen to let the rx/tx queues allocated for
115  * the netdevice to be fit in one page. So we can make sure the success of
116  * memory allocation. TODO: increase the limit. */
117 #define MAX_TAP_QUEUES DEFAULT_MAX_NUM_RSS_QUEUES
118 #define MAX_TAP_FLOWS  4096
119 
120 #define TUN_FLOW_EXPIRE (3 * HZ)
121 
122 /* A tun_file connects an open character device to a tuntap netdevice. It
123  * also contains all socket related structures (except sock_fprog and tap_filter)
124  * to serve as one transmit queue for tuntap device. The sock_fprog and
125  * tap_filter were kept in tun_struct since they were used for filtering for the
126  * netdevice not for a specific queue (at least I didn't see the requirement for
127  * this).
128  *
129  * RCU usage:
130  * The tun_file and tun_struct are loosely coupled, the pointer from one to the
131  * other can only be read while rcu_read_lock or rtnl_lock is held.
132  */
133 struct tun_file {
134         struct sock sk;
135         struct socket socket;
136         struct socket_wq wq;
137         struct tun_struct __rcu *tun;
138         struct net *net;
139         struct fasync_struct *fasync;
140         /* only used for fasnyc */
141         unsigned int flags;
142         union {
143                 u16 queue_index;
144                 unsigned int ifindex;
145         };
146         struct list_head next;
147         struct tun_struct *detached;
148 };
149 
150 struct tun_flow_entry {
151         struct hlist_node hash_link;
152         struct rcu_head rcu;
153         struct tun_struct *tun;
154 
155         u32 rxhash;
156         u32 rps_rxhash;
157         int queue_index;
158         unsigned long updated;
159 };
160 
161 #define TUN_NUM_FLOW_ENTRIES 1024
162 
163 /* Since the socket were moved to tun_file, to preserve the behavior of persist
164  * device, socket filter, sndbuf and vnet header size were restore when the
165  * file were attached to a persist device.
166  */
167 struct tun_struct {
168         struct tun_file __rcu   *tfiles[MAX_TAP_QUEUES];
169         unsigned int            numqueues;
170         unsigned int            flags;
171         kuid_t                  owner;
172         kgid_t                  group;
173 
174         struct net_device       *dev;
175         netdev_features_t       set_features;
176 #define TUN_USER_FEATURES (NETIF_F_HW_CSUM|NETIF_F_TSO_ECN|NETIF_F_TSO| \
177                           NETIF_F_TSO6|NETIF_F_UFO)
178 
179         int                     vnet_hdr_sz;
180         int                     sndbuf;
181         struct tap_filter       txflt;
182         struct sock_fprog       fprog;
183         /* protected by rtnl lock */
184         bool                    filter_attached;
185 #ifdef TUN_DEBUG
186         int debug;
187 #endif
188         spinlock_t lock;
189         struct hlist_head flows[TUN_NUM_FLOW_ENTRIES];
190         struct timer_list flow_gc_timer;
191         unsigned long ageing_time;
192         unsigned int numdisabled;
193         struct list_head disabled;
194         void *security;
195         u32 flow_count;
196 };
197 
198 static inline u32 tun_hashfn(u32 rxhash)
199 {
200         return rxhash & 0x3ff;
201 }
202 
203 static struct tun_flow_entry *tun_flow_find(struct hlist_head *head, u32 rxhash)
204 {
205         struct tun_flow_entry *e;
206 
207         hlist_for_each_entry_rcu(e, head, hash_link) {
208                 if (e->rxhash == rxhash)
209                         return e;
210         }
211         return NULL;
212 }
213 
214 static struct tun_flow_entry *tun_flow_create(struct tun_struct *tun,
215                                               struct hlist_head *head,
216                                               u32 rxhash, u16 queue_index)
217 {
218         struct tun_flow_entry *e = kmalloc(sizeof(*e), GFP_ATOMIC);
219 
220         if (e) {
221                 tun_debug(KERN_INFO, tun, "create flow: hash %u index %u\n",
222                           rxhash, queue_index);
223                 e->updated = jiffies;
224                 e->rxhash = rxhash;
225                 e->rps_rxhash = 0;
226                 e->queue_index = queue_index;
227                 e->tun = tun;
228                 hlist_add_head_rcu(&e->hash_link, head);
229                 ++tun->flow_count;
230         }
231         return e;
232 }
233 
234 static void tun_flow_delete(struct tun_struct *tun, struct tun_flow_entry *e)
235 {
236         tun_debug(KERN_INFO, tun, "delete flow: hash %u index %u\n",
237                   e->rxhash, e->queue_index);
238         sock_rps_reset_flow_hash(e->rps_rxhash);
239         hlist_del_rcu(&e->hash_link);
240         kfree_rcu(e, rcu);
241         --tun->flow_count;
242 }
243 
244 static void tun_flow_flush(struct tun_struct *tun)
245 {
246         int i;
247 
248         spin_lock_bh(&tun->lock);
249         for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) {
250                 struct tun_flow_entry *e;
251                 struct hlist_node *n;
252 
253                 hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link)
254                         tun_flow_delete(tun, e);
255         }
256         spin_unlock_bh(&tun->lock);
257 }
258 
259 static void tun_flow_delete_by_queue(struct tun_struct *tun, u16 queue_index)
260 {
261         int i;
262 
263         spin_lock_bh(&tun->lock);
264         for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) {
265                 struct tun_flow_entry *e;
266                 struct hlist_node *n;
267 
268                 hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link) {
269                         if (e->queue_index == queue_index)
270                                 tun_flow_delete(tun, e);
271                 }
272         }
273         spin_unlock_bh(&tun->lock);
274 }
275 
276 static void tun_flow_cleanup(unsigned long data)
277 {
278         struct tun_struct *tun = (struct tun_struct *)data;
279         unsigned long delay = tun->ageing_time;
280         unsigned long next_timer = jiffies + delay;
281         unsigned long count = 0;
282         int i;
283 
284         tun_debug(KERN_INFO, tun, "tun_flow_cleanup\n");
285 
286         spin_lock_bh(&tun->lock);
287         for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) {
288                 struct tun_flow_entry *e;
289                 struct hlist_node *n;
290 
291                 hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link) {
292                         unsigned long this_timer;
293                         count++;
294                         this_timer = e->updated + delay;
295                         if (time_before_eq(this_timer, jiffies))
296                                 tun_flow_delete(tun, e);
297                         else if (time_before(this_timer, next_timer))
298                                 next_timer = this_timer;
299                 }
300         }
301 
302         if (count)
303                 mod_timer(&tun->flow_gc_timer, round_jiffies_up(next_timer));
304         spin_unlock_bh(&tun->lock);
305 }
306 
307 static void tun_flow_update(struct tun_struct *tun, u32 rxhash,
308                             struct tun_file *tfile)
309 {
310         struct hlist_head *head;
311         struct tun_flow_entry *e;
312         unsigned long delay = tun->ageing_time;
313         u16 queue_index = tfile->queue_index;
314 
315         if (!rxhash)
316                 return;
317         else
318                 head = &tun->flows[tun_hashfn(rxhash)];
319 
320         rcu_read_lock();
321 
322         /* We may get a very small possibility of OOO during switching, not
323          * worth to optimize.*/
324         if (tun->numqueues == 1 || tfile->detached)
325                 goto unlock;
326 
327         e = tun_flow_find(head, rxhash);
328         if (likely(e)) {
329                 /* TODO: keep queueing to old queue until it's empty? */
330                 e->queue_index = queue_index;
331                 e->updated = jiffies;
332                 sock_rps_record_flow_hash(e->rps_rxhash);
333         } else {
334                 spin_lock_bh(&tun->lock);
335                 if (!tun_flow_find(head, rxhash) &&
336                     tun->flow_count < MAX_TAP_FLOWS)
337                         tun_flow_create(tun, head, rxhash, queue_index);
338 
339                 if (!timer_pending(&tun->flow_gc_timer))
340                         mod_timer(&tun->flow_gc_timer,
341                                   round_jiffies_up(jiffies + delay));
342                 spin_unlock_bh(&tun->lock);
343         }
344 
345 unlock:
346         rcu_read_unlock();
347 }
348 
349 /**
350  * Save the hash received in the stack receive path and update the
351  * flow_hash table accordingly.
352  */
353 static inline void tun_flow_save_rps_rxhash(struct tun_flow_entry *e, u32 hash)
354 {
355         if (unlikely(e->rps_rxhash != hash)) {
356                 sock_rps_reset_flow_hash(e->rps_rxhash);
357                 e->rps_rxhash = hash;
358         }
359 }
360 
361 /* We try to identify a flow through its rxhash first. The reason that
362  * we do not check rxq no. is because some cards(e.g 82599), chooses
363  * the rxq based on the txq where the last packet of the flow comes. As
364  * the userspace application move between processors, we may get a
365  * different rxq no. here. If we could not get rxhash, then we would
366  * hope the rxq no. may help here.
367  */
368 static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb,
369                             void *accel_priv, select_queue_fallback_t fallback)
370 {
371         struct tun_struct *tun = netdev_priv(dev);
372         struct tun_flow_entry *e;
373         u32 txq = 0;
374         u32 numqueues = 0;
375 
376         rcu_read_lock();
377         numqueues = ACCESS_ONCE(tun->numqueues);
378 
379         txq = skb_get_hash(skb);
380         if (txq) {
381                 e = tun_flow_find(&tun->flows[tun_hashfn(txq)], txq);
382                 if (e) {
383                         tun_flow_save_rps_rxhash(e, txq);
384                         txq = e->queue_index;
385                 } else
386                         /* use multiply and shift instead of expensive divide */
387                         txq = ((u64)txq * numqueues) >> 32;
388         } else if (likely(skb_rx_queue_recorded(skb))) {
389                 txq = skb_get_rx_queue(skb);
390                 while (unlikely(txq >= numqueues))
391                         txq -= numqueues;
392         }
393 
394         rcu_read_unlock();
395         return txq;
396 }
397 
398 static inline bool tun_not_capable(struct tun_struct *tun)
399 {
400         const struct cred *cred = current_cred();
401         struct net *net = dev_net(tun->dev);
402 
403         return ((uid_valid(tun->owner) && !uid_eq(cred->euid, tun->owner)) ||
404                   (gid_valid(tun->group) && !in_egroup_p(tun->group))) &&
405                 !ns_capable(net->user_ns, CAP_NET_ADMIN);
406 }
407 
408 static void tun_set_real_num_queues(struct tun_struct *tun)
409 {
410         netif_set_real_num_tx_queues(tun->dev, tun->numqueues);
411         netif_set_real_num_rx_queues(tun->dev, tun->numqueues);
412 }
413 
414 static void tun_disable_queue(struct tun_struct *tun, struct tun_file *tfile)
415 {
416         tfile->detached = tun;
417         list_add_tail(&tfile->next, &tun->disabled);
418         ++tun->numdisabled;
419 }
420 
421 static struct tun_struct *tun_enable_queue(struct tun_file *tfile)
422 {
423         struct tun_struct *tun = tfile->detached;
424 
425         tfile->detached = NULL;
426         list_del_init(&tfile->next);
427         --tun->numdisabled;
428         return tun;
429 }
430 
431 static void tun_queue_purge(struct tun_file *tfile)
432 {
433         skb_queue_purge(&tfile->sk.sk_receive_queue);
434         skb_queue_purge(&tfile->sk.sk_error_queue);
435 }
436 
437 static void __tun_detach(struct tun_file *tfile, bool clean)
438 {
439         struct tun_file *ntfile;
440         struct tun_struct *tun;
441 
442         tun = rtnl_dereference(tfile->tun);
443 
444         if (tun && !tfile->detached) {
445                 u16 index = tfile->queue_index;
446                 BUG_ON(index >= tun->numqueues);
447 
448                 rcu_assign_pointer(tun->tfiles[index],
449                                    tun->tfiles[tun->numqueues - 1]);
450                 ntfile = rtnl_dereference(tun->tfiles[index]);
451                 ntfile->queue_index = index;
452 
453                 --tun->numqueues;
454                 if (clean) {
455                         RCU_INIT_POINTER(tfile->tun, NULL);
456                         sock_put(&tfile->sk);
457                 } else
458                         tun_disable_queue(tun, tfile);
459 
460                 synchronize_net();
461                 tun_flow_delete_by_queue(tun, tun->numqueues + 1);
462                 /* Drop read queue */
463                 tun_queue_purge(tfile);
464                 tun_set_real_num_queues(tun);
465         } else if (tfile->detached && clean) {
466                 tun = tun_enable_queue(tfile);
467                 sock_put(&tfile->sk);
468         }
469 
470         if (clean) {
471                 if (tun && tun->numqueues == 0 && tun->numdisabled == 0) {
472                         netif_carrier_off(tun->dev);
473 
474                         if (!(tun->flags & TUN_PERSIST) &&
475                             tun->dev->reg_state == NETREG_REGISTERED)
476                                 unregister_netdevice(tun->dev);
477                 }
478 
479                 BUG_ON(!test_bit(SOCK_EXTERNALLY_ALLOCATED,
480                                  &tfile->socket.flags));
481                 sk_release_kernel(&tfile->sk);
482         }
483 }
484 
485 static void tun_detach(struct tun_file *tfile, bool clean)
486 {
487         rtnl_lock();
488         __tun_detach(tfile, clean);
489         rtnl_unlock();
490 }
491 
492 static void tun_detach_all(struct net_device *dev)
493 {
494         struct tun_struct *tun = netdev_priv(dev);
495         struct tun_file *tfile, *tmp;
496         int i, n = tun->numqueues;
497 
498         for (i = 0; i < n; i++) {
499                 tfile = rtnl_dereference(tun->tfiles[i]);
500                 BUG_ON(!tfile);
501                 wake_up_all(&tfile->wq.wait);
502                 RCU_INIT_POINTER(tfile->tun, NULL);
503                 --tun->numqueues;
504         }
505         list_for_each_entry(tfile, &tun->disabled, next) {
506                 wake_up_all(&tfile->wq.wait);
507                 RCU_INIT_POINTER(tfile->tun, NULL);
508         }
509         BUG_ON(tun->numqueues != 0);
510 
511         synchronize_net();
512         for (i = 0; i < n; i++) {
513                 tfile = rtnl_dereference(tun->tfiles[i]);
514                 /* Drop read queue */
515                 tun_queue_purge(tfile);
516                 sock_put(&tfile->sk);
517         }
518         list_for_each_entry_safe(tfile, tmp, &tun->disabled, next) {
519                 tun_enable_queue(tfile);
520                 tun_queue_purge(tfile);
521                 sock_put(&tfile->sk);
522         }
523         BUG_ON(tun->numdisabled != 0);
524 
525         if (tun->flags & TUN_PERSIST)
526                 module_put(THIS_MODULE);
527 }
528 
529 static int tun_attach(struct tun_struct *tun, struct file *file, bool skip_filter)
530 {
531         struct tun_file *tfile = file->private_data;
532         int err;
533 
534         err = security_tun_dev_attach(tfile->socket.sk, tun->security);
535         if (err < 0)
536                 goto out;
537 
538         err = -EINVAL;
539         if (rtnl_dereference(tfile->tun) && !tfile->detached)
540                 goto out;
541 
542         err = -EBUSY;
543         if (!(tun->flags & TUN_TAP_MQ) && tun->numqueues == 1)
544                 goto out;
545 
546         err = -E2BIG;
547         if (!tfile->detached &&
548             tun->numqueues + tun->numdisabled == MAX_TAP_QUEUES)
549                 goto out;
550 
551         err = 0;
552 
553         /* Re-attach the filter to persist device */
554         if (!skip_filter && (tun->filter_attached == true)) {
555                 err = sk_attach_filter(&tun->fprog, tfile->socket.sk);
556                 if (!err)
557                         goto out;
558         }
559         tfile->queue_index = tun->numqueues;
560         rcu_assign_pointer(tfile->tun, tun);
561         rcu_assign_pointer(tun->tfiles[tun->numqueues], tfile);
562         tun->numqueues++;
563 
564         if (tfile->detached)
565                 tun_enable_queue(tfile);
566         else
567                 sock_hold(&tfile->sk);
568 
569         tun_set_real_num_queues(tun);
570 
571         /* device is allowed to go away first, so no need to hold extra
572          * refcnt.
573          */
574 
575 out:
576         return err;
577 }
578 
579 static struct tun_struct *__tun_get(struct tun_file *tfile)
580 {
581         struct tun_struct *tun;
582 
583         rcu_read_lock();
584         tun = rcu_dereference(tfile->tun);
585         if (tun)
586                 dev_hold(tun->dev);
587         rcu_read_unlock();
588 
589         return tun;
590 }
591 
592 static struct tun_struct *tun_get(struct file *file)
593 {
594         return __tun_get(file->private_data);
595 }
596 
597 static void tun_put(struct tun_struct *tun)
598 {
599         dev_put(tun->dev);
600 }
601 
602 /* TAP filtering */
603 static void addr_hash_set(u32 *mask, const u8 *addr)
604 {
605         int n = ether_crc(ETH_ALEN, addr) >> 26;
606         mask[n >> 5] |= (1 << (n & 31));
607 }
608 
609 static unsigned int addr_hash_test(const u32 *mask, const u8 *addr)
610 {
611         int n = ether_crc(ETH_ALEN, addr) >> 26;
612         return mask[n >> 5] & (1 << (n & 31));
613 }
614 
615 static int update_filter(struct tap_filter *filter, void __user *arg)
616 {
617         struct { u8 u[ETH_ALEN]; } *addr;
618         struct tun_filter uf;
619         int err, alen, n, nexact;
620 
621         if (copy_from_user(&uf, arg, sizeof(uf)))
622                 return -EFAULT;
623 
624         if (!uf.count) {
625                 /* Disabled */
626                 filter->count = 0;
627                 return 0;
628         }
629 
630         alen = ETH_ALEN * uf.count;
631         addr = kmalloc(alen, GFP_KERNEL);
632         if (!addr)
633                 return -ENOMEM;
634 
635         if (copy_from_user(addr, arg + sizeof(uf), alen)) {
636                 err = -EFAULT;
637                 goto done;
638         }
639 
640         /* The filter is updated without holding any locks. Which is
641          * perfectly safe. We disable it first and in the worst
642          * case we'll accept a few undesired packets. */
643         filter->count = 0;
644         wmb();
645 
646         /* Use first set of addresses as an exact filter */
647         for (n = 0; n < uf.count && n < FLT_EXACT_COUNT; n++)
648                 memcpy(filter->addr[n], addr[n].u, ETH_ALEN);
649 
650         nexact = n;
651 
652         /* Remaining multicast addresses are hashed,
653          * unicast will leave the filter disabled. */
654         memset(filter->mask, 0, sizeof(filter->mask));
655         for (; n < uf.count; n++) {
656                 if (!is_multicast_ether_addr(addr[n].u)) {
657                         err = 0; /* no filter */
658                         goto done;
659                 }
660                 addr_hash_set(filter->mask, addr[n].u);
661         }
662 
663         /* For ALLMULTI just set the mask to all ones.
664          * This overrides the mask populated above. */
665         if ((uf.flags & TUN_FLT_ALLMULTI))
666                 memset(filter->mask, ~0, sizeof(filter->mask));
667 
668         /* Now enable the filter */
669         wmb();
670         filter->count = nexact;
671 
672         /* Return the number of exact filters */
673         err = nexact;
674 
675 done:
676         kfree(addr);
677         return err;
678 }
679 
680 /* Returns: 0 - drop, !=0 - accept */
681 static int run_filter(struct tap_filter *filter, const struct sk_buff *skb)
682 {
683         /* Cannot use eth_hdr(skb) here because skb_mac_hdr() is incorrect
684          * at this point. */
685         struct ethhdr *eh = (struct ethhdr *) skb->data;
686         int i;
687 
688         /* Exact match */
689         for (i = 0; i < filter->count; i++)
690                 if (ether_addr_equal(eh->h_dest, filter->addr[i]))
691                         return 1;
692 
693         /* Inexact match (multicast only) */
694         if (is_multicast_ether_addr(eh->h_dest))
695                 return addr_hash_test(filter->mask, eh->h_dest);
696 
697         return 0;
698 }
699 
700 /*
701  * Checks whether the packet is accepted or not.
702  * Returns: 0 - drop, !=0 - accept
703  */
704 static int check_filter(struct tap_filter *filter, const struct sk_buff *skb)
705 {
706         if (!filter->count)
707                 return 1;
708 
709         return run_filter(filter, skb);
710 }
711 
712 /* Network device part of the driver */
713 
714 static const struct ethtool_ops tun_ethtool_ops;
715 
716 /* Net device detach from fd. */
717 static void tun_net_uninit(struct net_device *dev)
718 {
719         tun_detach_all(dev);
720 }
721 
722 /* Net device open. */
723 static int tun_net_open(struct net_device *dev)
724 {
725         netif_tx_start_all_queues(dev);
726         return 0;
727 }
728 
729 /* Net device close. */
730 static int tun_net_close(struct net_device *dev)
731 {
732         netif_tx_stop_all_queues(dev);
733         return 0;
734 }
735 
736 /* Net device start xmit */
737 static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
738 {
739         struct tun_struct *tun = netdev_priv(dev);
740         int txq = skb->queue_mapping;
741         struct tun_file *tfile;
742         u32 numqueues = 0;
743 
744         rcu_read_lock();
745         tfile = rcu_dereference(tun->tfiles[txq]);
746         numqueues = ACCESS_ONCE(tun->numqueues);
747 
748         /* Drop packet if interface is not attached */
749         if (txq >= numqueues)
750                 goto drop;
751 
752         if (numqueues == 1) {
753                 /* Select queue was not called for the skbuff, so we extract the
754                  * RPS hash and save it into the flow_table here.
755                  */
756                 __u32 rxhash;
757 
758                 rxhash = skb_get_hash(skb);
759                 if (rxhash) {
760                         struct tun_flow_entry *e;
761                         e = tun_flow_find(&tun->flows[tun_hashfn(rxhash)],
762                                         rxhash);
763                         if (e)
764                                 tun_flow_save_rps_rxhash(e, rxhash);
765                 }
766         }
767 
768         tun_debug(KERN_INFO, tun, "tun_net_xmit %d\n", skb->len);
769 
770         BUG_ON(!tfile);
771 
772         /* Drop if the filter does not like it.
773          * This is a noop if the filter is disabled.
774          * Filter can be enabled only for the TAP devices. */
775         if (!check_filter(&tun->txflt, skb))
776                 goto drop;
777 
778         if (tfile->socket.sk->sk_filter &&
779             sk_filter(tfile->socket.sk, skb))
780                 goto drop;
781 
782         /* Limit the number of packets queued by dividing txq length with the
783          * number of queues.
784          */
785         if (skb_queue_len(&tfile->socket.sk->sk_receive_queue) * numqueues
786                           >= dev->tx_queue_len)
787                 goto drop;
788 
789         if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC)))
790                 goto drop;
791 
792         if (skb->sk) {
793                 sock_tx_timestamp(skb->sk, &skb_shinfo(skb)->tx_flags);
794                 sw_tx_timestamp(skb);
795         }
796 
797         /* Orphan the skb - required as we might hang on to it
798          * for indefinite time.
799          */
800         skb_orphan(skb);
801 
802         nf_reset(skb);
803 
804         /* Enqueue packet */
805         skb_queue_tail(&tfile->socket.sk->sk_receive_queue, skb);
806 
807         /* Notify and wake up reader process */
808         if (tfile->flags & TUN_FASYNC)
809                 kill_fasync(&tfile->fasync, SIGIO, POLL_IN);
810         wake_up_interruptible_poll(&tfile->wq.wait, POLLIN |
811                                    POLLRDNORM | POLLRDBAND);
812 
813         rcu_read_unlock();
814         return NETDEV_TX_OK;
815 
816 drop:
817         dev->stats.tx_dropped++;
818         skb_tx_error(skb);
819         kfree_skb(skb);
820         rcu_read_unlock();
821         return NETDEV_TX_OK;
822 }
823 
824 static void tun_net_mclist(struct net_device *dev)
825 {
826         /*
827          * This callback is supposed to deal with mc filter in
828          * _rx_ path and has nothing to do with the _tx_ path.
829          * In rx path we always accept everything userspace gives us.
830          */
831 }
832 
833 #define MIN_MTU 68
834 #define MAX_MTU 65535
835 
836 static int
837 tun_net_change_mtu(struct net_device *dev, int new_mtu)
838 {
839         if (new_mtu < MIN_MTU || new_mtu + dev->hard_header_len > MAX_MTU)
840                 return -EINVAL;
841         dev->mtu = new_mtu;
842         return 0;
843 }
844 
845 static netdev_features_t tun_net_fix_features(struct net_device *dev,
846         netdev_features_t features)
847 {
848         struct tun_struct *tun = netdev_priv(dev);
849 
850         return (features & tun->set_features) | (features & ~TUN_USER_FEATURES);
851 }
852 #ifdef CONFIG_NET_POLL_CONTROLLER
853 static void tun_poll_controller(struct net_device *dev)
854 {
855         /*
856          * Tun only receives frames when:
857          * 1) the char device endpoint gets data from user space
858          * 2) the tun socket gets a sendmsg call from user space
859          * Since both of those are synchronous operations, we are guaranteed
860          * never to have pending data when we poll for it
861          * so there is nothing to do here but return.
862          * We need this though so netpoll recognizes us as an interface that
863          * supports polling, which enables bridge devices in virt setups to
864          * still use netconsole
865          */
866         return;
867 }
868 #endif
869 static const struct net_device_ops tun_netdev_ops = {
870         .ndo_uninit             = tun_net_uninit,
871         .ndo_open               = tun_net_open,
872         .ndo_stop               = tun_net_close,
873         .ndo_start_xmit         = tun_net_xmit,
874         .ndo_change_mtu         = tun_net_change_mtu,
875         .ndo_fix_features       = tun_net_fix_features,
876         .ndo_select_queue       = tun_select_queue,
877 #ifdef CONFIG_NET_POLL_CONTROLLER
878         .ndo_poll_controller    = tun_poll_controller,
879 #endif
880 };
881 
882 static const struct net_device_ops tap_netdev_ops = {
883         .ndo_uninit             = tun_net_uninit,
884         .ndo_open               = tun_net_open,
885         .ndo_stop               = tun_net_close,
886         .ndo_start_xmit         = tun_net_xmit,
887         .ndo_change_mtu         = tun_net_change_mtu,
888         .ndo_fix_features       = tun_net_fix_features,
889         .ndo_set_rx_mode        = tun_net_mclist,
890         .ndo_set_mac_address    = eth_mac_addr,
891         .ndo_validate_addr      = eth_validate_addr,
892         .ndo_select_queue       = tun_select_queue,
893 #ifdef CONFIG_NET_POLL_CONTROLLER
894         .ndo_poll_controller    = tun_poll_controller,
895 #endif
896 };
897 
898 static void tun_flow_init(struct tun_struct *tun)
899 {
900         int i;
901 
902         for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++)
903                 INIT_HLIST_HEAD(&tun->flows[i]);
904 
905         tun->ageing_time = TUN_FLOW_EXPIRE;
906         setup_timer(&tun->flow_gc_timer, tun_flow_cleanup, (unsigned long)tun);
907         mod_timer(&tun->flow_gc_timer,
908                   round_jiffies_up(jiffies + tun->ageing_time));
909 }
910 
911 static void tun_flow_uninit(struct tun_struct *tun)
912 {
913         del_timer_sync(&tun->flow_gc_timer);
914         tun_flow_flush(tun);
915 }
916 
917 /* Initialize net device. */
918 static void tun_net_init(struct net_device *dev)
919 {
920         struct tun_struct *tun = netdev_priv(dev);
921 
922         switch (tun->flags & TUN_TYPE_MASK) {
923         case TUN_TUN_DEV:
924                 dev->netdev_ops = &tun_netdev_ops;
925 
926                 /* Point-to-Point TUN Device */
927                 dev->hard_header_len = 0;
928                 dev->addr_len = 0;
929                 dev->mtu = 1500;
930 
931                 /* Zero header length */
932                 dev->type = ARPHRD_NONE;
933                 dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
934                 dev->tx_queue_len = TUN_READQ_SIZE;  /* We prefer our own queue length */
935                 break;
936 
937         case TUN_TAP_DEV:
938                 dev->netdev_ops = &tap_netdev_ops;
939                 /* Ethernet TAP Device */
940                 ether_setup(dev);
941                 dev->priv_flags &= ~IFF_TX_SKB_SHARING;
942                 dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
943 
944                 eth_hw_addr_random(dev);
945 
946                 dev->tx_queue_len = TUN_READQ_SIZE;  /* We prefer our own queue length */
947                 break;
948         }
949 }
950 
951 /* Character device part */
952 
953 /* Poll */
954 static unsigned int tun_chr_poll(struct file *file, poll_table *wait)
955 {
956         struct tun_file *tfile = file->private_data;
957         struct tun_struct *tun = __tun_get(tfile);
958         struct sock *sk;
959         unsigned int mask = 0;
960 
961         if (!tun)
962                 return POLLERR;
963 
964         sk = tfile->socket.sk;
965 
966         tun_debug(KERN_INFO, tun, "tun_chr_poll\n");
967 
968         poll_wait(file, &tfile->wq.wait, wait);
969 
970         if (!skb_queue_empty(&sk->sk_receive_queue))
971                 mask |= POLLIN | POLLRDNORM;
972 
973         if (sock_writeable(sk) ||
974             (!test_and_set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags) &&
975              sock_writeable(sk)))
976                 mask |= POLLOUT | POLLWRNORM;
977 
978         if (tun->dev->reg_state != NETREG_REGISTERED)
979                 mask = POLLERR;
980 
981         tun_put(tun);
982         return mask;
983 }
984 
985 /* prepad is the amount to reserve at front.  len is length after that.
986  * linear is a hint as to how much to copy (usually headers). */
987 static struct sk_buff *tun_alloc_skb(struct tun_file *tfile,
988                                      size_t prepad, size_t len,
989                                      size_t linear, int noblock)
990 {
991         struct sock *sk = tfile->socket.sk;
992         struct sk_buff *skb;
993         int err;
994 
995         /* Under a page?  Don't bother with paged skb. */
996         if (prepad + len < PAGE_SIZE || !linear)
997                 linear = len;
998 
999         skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
1000                                    &err, 0);
1001         if (!skb)
1002                 return ERR_PTR(err);
1003 
1004         skb_reserve(skb, prepad);
1005         skb_put(skb, linear);
1006         skb->data_len = len - linear;
1007         skb->len += len - linear;
1008 
1009         return skb;
1010 }
1011 
1012 /* Get packet from user space buffer */
1013 static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
1014                             void *msg_control, const struct iovec *iv,
1015                             size_t total_len, size_t count, int noblock)
1016 {
1017         struct tun_pi pi = { 0, cpu_to_be16(ETH_P_IP) };
1018         struct sk_buff *skb;
1019         size_t len = total_len, align = NET_SKB_PAD, linear;
1020         struct virtio_net_hdr gso = { 0 };
1021         int good_linear;
1022         int offset = 0;
1023         int copylen;
1024         bool zerocopy = false;
1025         int err;
1026         u32 rxhash;
1027 
1028         if (!(tun->flags & TUN_NO_PI)) {
1029                 if (len < sizeof(pi))
1030                         return -EINVAL;
1031                 len -= sizeof(pi);
1032 
1033                 if (memcpy_fromiovecend((void *)&pi, iv, 0, sizeof(pi)))
1034                         return -EFAULT;
1035                 offset += sizeof(pi);
1036         }
1037 
1038         if (tun->flags & TUN_VNET_HDR) {
1039                 if (len < tun->vnet_hdr_sz)
1040                         return -EINVAL;
1041                 len -= tun->vnet_hdr_sz;
1042 
1043                 if (memcpy_fromiovecend((void *)&gso, iv, offset, sizeof(gso)))
1044                         return -EFAULT;
1045 
1046                 if ((gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
1047                     gso.csum_start + gso.csum_offset + 2 > gso.hdr_len)
1048                         gso.hdr_len = gso.csum_start + gso.csum_offset + 2;
1049 
1050                 if (gso.hdr_len > len)
1051                         return -EINVAL;
1052                 offset += tun->vnet_hdr_sz;
1053         }
1054 
1055         if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV) {
1056                 align += NET_IP_ALIGN;
1057                 if (unlikely(len < ETH_HLEN ||
1058                              (gso.hdr_len && gso.hdr_len < ETH_HLEN)))
1059                         return -EINVAL;
1060         }
1061 
1062         good_linear = SKB_MAX_HEAD(align);
1063 
1064         if (msg_control) {
1065                 /* There are 256 bytes to be copied in skb, so there is
1066                  * enough room for skb expand head in case it is used.
1067                  * The rest of the buffer is mapped from userspace.
1068                  */
1069                 copylen = gso.hdr_len ? gso.hdr_len : GOODCOPY_LEN;
1070                 if (copylen > good_linear)
1071                         copylen = good_linear;
1072                 linear = copylen;
1073                 if (iov_pages(iv, offset + copylen, count) <= MAX_SKB_FRAGS)
1074                         zerocopy = true;
1075         }
1076 
1077         if (!zerocopy) {
1078                 copylen = len;
1079                 if (gso.hdr_len > good_linear)
1080                         linear = good_linear;
1081                 else
1082                         linear = gso.hdr_len;
1083         }
1084 
1085         skb = tun_alloc_skb(tfile, align, copylen, linear, noblock);
1086         if (IS_ERR(skb)) {
1087                 if (PTR_ERR(skb) != -EAGAIN)
1088                         tun->dev->stats.rx_dropped++;
1089                 return PTR_ERR(skb);
1090         }
1091 
1092         if (zerocopy)
1093                 err = zerocopy_sg_from_iovec(skb, iv, offset, count);
1094         else {
1095                 err = skb_copy_datagram_from_iovec(skb, 0, iv, offset, len);
1096                 if (!err && msg_control) {
1097                         struct ubuf_info *uarg = msg_control;
1098                         uarg->callback(uarg, false);
1099                 }
1100         }
1101 
1102         if (err) {
1103                 tun->dev->stats.rx_dropped++;
1104                 kfree_skb(skb);
1105                 return -EFAULT;
1106         }
1107 
1108         if (gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
1109                 if (!skb_partial_csum_set(skb, gso.csum_start,
1110                                           gso.csum_offset)) {
1111                         tun->dev->stats.rx_frame_errors++;
1112                         kfree_skb(skb);
1113                         return -EINVAL;
1114                 }
1115         }
1116 
1117         switch (tun->flags & TUN_TYPE_MASK) {
1118         case TUN_TUN_DEV:
1119                 if (tun->flags & TUN_NO_PI) {
1120                         switch (skb->data[0] & 0xf0) {
1121                         case 0x40:
1122                                 pi.proto = htons(ETH_P_IP);
1123                                 break;
1124                         case 0x60:
1125                                 pi.proto = htons(ETH_P_IPV6);
1126                                 break;
1127                         default:
1128                                 tun->dev->stats.rx_dropped++;
1129                                 kfree_skb(skb);
1130                                 return -EINVAL;
1131                         }
1132                 }
1133 
1134                 skb_reset_mac_header(skb);
1135                 skb->protocol = pi.proto;
1136                 skb->dev = tun->dev;
1137                 break;
1138         case TUN_TAP_DEV:
1139                 skb->protocol = eth_type_trans(skb, tun->dev);
1140                 break;
1141         }
1142 
1143         if (gso.gso_type != VIRTIO_NET_HDR_GSO_NONE) {
1144                 pr_debug("GSO!\n");
1145                 switch (gso.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
1146                 case VIRTIO_NET_HDR_GSO_TCPV4:
1147                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
1148                         break;
1149                 case VIRTIO_NET_HDR_GSO_TCPV6:
1150                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
1151                         break;
1152                 case VIRTIO_NET_HDR_GSO_UDP:
1153                         skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1154                         break;
1155                 default:
1156                         tun->dev->stats.rx_frame_errors++;
1157                         kfree_skb(skb);
1158                         return -EINVAL;
1159                 }
1160 
1161                 if (gso.gso_type & VIRTIO_NET_HDR_GSO_ECN)
1162                         skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
1163 
1164                 skb_shinfo(skb)->gso_size = gso.gso_size;
1165                 if (skb_shinfo(skb)->gso_size == 0) {
1166                         tun->dev->stats.rx_frame_errors++;
1167                         kfree_skb(skb);
1168                         return -EINVAL;
1169                 }
1170 
1171                 /* Header must be checked, and gso_segs computed. */
1172                 skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
1173                 skb_shinfo(skb)->gso_segs = 0;
1174         }
1175 
1176         /* copy skb_ubuf_info for callback when skb has no error */
1177         if (zerocopy) {
1178                 skb_shinfo(skb)->destructor_arg = msg_control;
1179                 skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
1180                 skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
1181         }
1182 
1183         skb_reset_network_header(skb);
1184         skb_probe_transport_header(skb, 0);
1185 
1186         rxhash = skb_get_hash(skb);
1187         netif_rx_ni(skb);
1188 
1189         tun->dev->stats.rx_packets++;
1190         tun->dev->stats.rx_bytes += len;
1191 
1192         tun_flow_update(tun, rxhash, tfile);
1193         return total_len;
1194 }
1195 
1196 static ssize_t tun_chr_aio_write(struct kiocb *iocb, const struct iovec *iv,
1197                               unsigned long count, loff_t pos)
1198 {
1199         struct file *file = iocb->ki_filp;
1200         struct tun_struct *tun = tun_get(file);
1201         struct tun_file *tfile = file->private_data;
1202         ssize_t result;
1203 
1204         if (!tun)
1205                 return -EBADFD;
1206 
1207         tun_debug(KERN_INFO, tun, "tun_chr_write %ld\n", count);
1208 
1209         result = tun_get_user(tun, tfile, NULL, iv, iov_length(iv, count),
1210                               count, file->f_flags & O_NONBLOCK);
1211 
1212         tun_put(tun);
1213         return result;
1214 }
1215 
1216 /* Put packet to the user space buffer */
1217 static ssize_t tun_put_user(struct tun_struct *tun,
1218                             struct tun_file *tfile,
1219                             struct sk_buff *skb,
1220                             const struct iovec *iv, int len)
1221 {
1222         struct tun_pi pi = { 0, skb->protocol };
1223         ssize_t total = 0;
1224         int vlan_offset = 0, copied;
1225 
1226         if (!(tun->flags & TUN_NO_PI)) {
1227                 if ((len -= sizeof(pi)) < 0)
1228                         return -EINVAL;
1229 
1230                 if (len < skb->len) {
1231                         /* Packet will be striped */
1232                         pi.flags |= TUN_PKT_STRIP;
1233                 }
1234 
1235                 if (memcpy_toiovecend(iv, (void *) &pi, 0, sizeof(pi)))
1236                         return -EFAULT;
1237                 total += sizeof(pi);
1238         }
1239 
1240         if (tun->flags & TUN_VNET_HDR) {
1241                 struct virtio_net_hdr gso = { 0 }; /* no info leak */
1242                 if ((len -= tun->vnet_hdr_sz) < 0)
1243                         return -EINVAL;
1244 
1245                 if (skb_is_gso(skb)) {
1246                         struct skb_shared_info *sinfo = skb_shinfo(skb);
1247 
1248                         /* This is a hint as to how much should be linear. */
1249                         gso.hdr_len = skb_headlen(skb);
1250                         gso.gso_size = sinfo->gso_size;
1251                         if (sinfo->gso_type & SKB_GSO_TCPV4)
1252                                 gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
1253                         else if (sinfo->gso_type & SKB_GSO_TCPV6)
1254                                 gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
1255                         else if (sinfo->gso_type & SKB_GSO_UDP)
1256                                 gso.gso_type = VIRTIO_NET_HDR_GSO_UDP;
1257                         else {
1258                                 pr_err("unexpected GSO type: "
1259                                        "0x%x, gso_size %d, hdr_len %d\n",
1260                                        sinfo->gso_type, gso.gso_size,
1261                                        gso.hdr_len);
1262                                 print_hex_dump(KERN_ERR, "tun: ",
1263                                                DUMP_PREFIX_NONE,
1264                                                16, 1, skb->head,
1265                                                min((int)gso.hdr_len, 64), true);
1266                                 WARN_ON_ONCE(1);
1267                                 return -EINVAL;
1268                         }
1269                         if (sinfo->gso_type & SKB_GSO_TCP_ECN)
1270                                 gso.gso_type |= VIRTIO_NET_HDR_GSO_ECN;
1271                 } else
1272                         gso.gso_type = VIRTIO_NET_HDR_GSO_NONE;
1273 
1274                 if (skb->ip_summed == CHECKSUM_PARTIAL) {
1275                         gso.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
1276                         gso.csum_start = skb_checksum_start_offset(skb);
1277                         gso.csum_offset = skb->csum_offset;
1278                 } else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
1279                         gso.flags = VIRTIO_NET_HDR_F_DATA_VALID;
1280                 } /* else everything is zero */
1281 
1282                 if (unlikely(memcpy_toiovecend(iv, (void *)&gso, total,
1283                                                sizeof(gso))))
1284                         return -EFAULT;
1285                 total += tun->vnet_hdr_sz;
1286         }
1287 
1288         copied = total;
1289         total += skb->len;
1290         if (!vlan_tx_tag_present(skb)) {
1291                 len = min_t(int, skb->len, len);
1292         } else {
1293                 int copy, ret;
1294                 struct {
1295                         __be16 h_vlan_proto;
1296                         __be16 h_vlan_TCI;
1297                 } veth;
1298 
1299                 veth.h_vlan_proto = skb->vlan_proto;
1300                 veth.h_vlan_TCI = htons(vlan_tx_tag_get(skb));
1301 
1302                 vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
1303                 len = min_t(int, skb->len + VLAN_HLEN, len);
1304                 total += VLAN_HLEN;
1305 
1306                 copy = min_t(int, vlan_offset, len);
1307                 ret = skb_copy_datagram_const_iovec(skb, 0, iv, copied, copy);
1308                 len -= copy;
1309                 copied += copy;
1310                 if (ret || !len)
1311                         goto done;
1312 
1313                 copy = min_t(int, sizeof(veth), len);
1314                 ret = memcpy_toiovecend(iv, (void *)&veth, copied, copy);
1315                 len -= copy;
1316                 copied += copy;
1317                 if (ret || !len)
1318                         goto done;
1319         }
1320 
1321         skb_copy_datagram_const_iovec(skb, vlan_offset, iv, copied, len);
1322 
1323 done:
1324         tun->dev->stats.tx_packets++;
1325         tun->dev->stats.tx_bytes += len;
1326 
1327         return total;
1328 }
1329 
1330 static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
1331                            const struct iovec *iv, ssize_t len, int noblock)
1332 {
1333         DECLARE_WAITQUEUE(wait, current);
1334         struct sk_buff *skb;
1335         ssize_t ret = 0;
1336 
1337         tun_debug(KERN_INFO, tun, "tun_do_read\n");
1338 
1339         if (unlikely(!noblock))
1340                 add_wait_queue(&tfile->wq.wait, &wait);
1341         while (len) {
1342                 if (unlikely(!noblock))
1343                         current->state = TASK_INTERRUPTIBLE;
1344 
1345                 /* Read frames from the queue */
1346                 if (!(skb = skb_dequeue(&tfile->socket.sk->sk_receive_queue))) {
1347                         if (noblock) {
1348                                 ret = -EAGAIN;
1349                                 break;
1350                         }
1351                         if (signal_pending(current)) {
1352                                 ret = -ERESTARTSYS;
1353                                 break;
1354                         }
1355                         if (tun->dev->reg_state != NETREG_REGISTERED) {
1356                                 ret = -EIO;
1357                                 break;
1358                         }
1359 
1360                         /* Nothing to read, let's sleep */
1361                         schedule();
1362                         continue;
1363                 }
1364 
1365                 ret = tun_put_user(tun, tfile, skb, iv, len);
1366                 kfree_skb(skb);
1367                 break;
1368         }
1369 
1370         if (unlikely(!noblock)) {
1371                 current->state = TASK_RUNNING;
1372                 remove_wait_queue(&tfile->wq.wait, &wait);
1373         }
1374 
1375         return ret;
1376 }
1377 
1378 static ssize_t tun_chr_aio_read(struct kiocb *iocb, const struct iovec *iv,
1379                             unsigned long count, loff_t pos)
1380 {
1381         struct file *file = iocb->ki_filp;
1382         struct tun_file *tfile = file->private_data;
1383         struct tun_struct *tun = __tun_get(tfile);
1384         ssize_t len, ret;
1385 
1386         if (!tun)
1387                 return -EBADFD;
1388         len = iov_length(iv, count);
1389         if (len < 0) {
1390                 ret = -EINVAL;
1391                 goto out;
1392         }
1393 
1394         ret = tun_do_read(tun, tfile, iv, len,
1395                           file->f_flags & O_NONBLOCK);
1396         ret = min_t(ssize_t, ret, len);
1397         if (ret > 0)
1398                 iocb->ki_pos = ret;
1399 out:
1400         tun_put(tun);
1401         return ret;
1402 }
1403 
1404 static void tun_free_netdev(struct net_device *dev)
1405 {
1406         struct tun_struct *tun = netdev_priv(dev);
1407 
1408         BUG_ON(!(list_empty(&tun->disabled)));
1409         tun_flow_uninit(tun);
1410         security_tun_dev_free_security(tun->security);
1411         free_netdev(dev);
1412 }
1413 
1414 static void tun_setup(struct net_device *dev)
1415 {
1416         struct tun_struct *tun = netdev_priv(dev);
1417 
1418         tun->owner = INVALID_UID;
1419         tun->group = INVALID_GID;
1420 
1421         dev->ethtool_ops = &tun_ethtool_ops;
1422         dev->destructor = tun_free_netdev;
1423 }
1424 
1425 /* Trivial set of netlink ops to allow deleting tun or tap
1426  * device with netlink.
1427  */
1428 static int tun_validate(struct nlattr *tb[], struct nlattr *data[])
1429 {
1430         return -EINVAL;
1431 }
1432 
1433 static struct rtnl_link_ops tun_link_ops __read_mostly = {
1434         .kind           = DRV_NAME,
1435         .priv_size      = sizeof(struct tun_struct),
1436         .setup          = tun_setup,
1437         .validate       = tun_validate,
1438 };
1439 
1440 static void tun_sock_write_space(struct sock *sk)
1441 {
1442         struct tun_file *tfile;
1443         wait_queue_head_t *wqueue;
1444 
1445         if (!sock_writeable(sk))
1446                 return;
1447 
1448         if (!test_and_clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags))
1449                 return;
1450 
1451         wqueue = sk_sleep(sk);
1452         if (wqueue && waitqueue_active(wqueue))
1453                 wake_up_interruptible_sync_poll(wqueue, POLLOUT |
1454                                                 POLLWRNORM | POLLWRBAND);
1455 
1456         tfile = container_of(sk, struct tun_file, sk);
1457         kill_fasync(&tfile->fasync, SIGIO, POLL_OUT);
1458 }
1459 
1460 static int tun_sendmsg(struct kiocb *iocb, struct socket *sock,
1461                        struct msghdr *m, size_t total_len)
1462 {
1463         int ret;
1464         struct tun_file *tfile = container_of(sock, struct tun_file, socket);
1465         struct tun_struct *tun = __tun_get(tfile);
1466 
1467         if (!tun)
1468                 return -EBADFD;
1469         ret = tun_get_user(tun, tfile, m->msg_control, m->msg_iov, total_len,
1470                            m->msg_iovlen, m->msg_flags & MSG_DONTWAIT);
1471         tun_put(tun);
1472         return ret;
1473 }
1474 
1475 static int tun_recvmsg(struct kiocb *iocb, struct socket *sock,
1476                        struct msghdr *m, size_t total_len,
1477                        int flags)
1478 {
1479         struct tun_file *tfile = container_of(sock, struct tun_file, socket);
1480         struct tun_struct *tun = __tun_get(tfile);
1481         int ret;
1482 
1483         if (!tun)
1484                 return -EBADFD;
1485 
1486         if (flags & ~(MSG_DONTWAIT|MSG_TRUNC|MSG_ERRQUEUE)) {
1487                 ret = -EINVAL;
1488                 goto out;
1489         }
1490         if (flags & MSG_ERRQUEUE) {
1491                 ret = sock_recv_errqueue(sock->sk, m, total_len,
1492                                          SOL_PACKET, TUN_TX_TIMESTAMP);
1493                 goto out;
1494         }
1495         ret = tun_do_read(tun, tfile, m->msg_iov, total_len,
1496                           flags & MSG_DONTWAIT);
1497         if (ret > total_len) {
1498                 m->msg_flags |= MSG_TRUNC;
1499                 ret = flags & MSG_TRUNC ? ret : total_len;
1500         }
1501 out:
1502         tun_put(tun);
1503         return ret;
1504 }
1505 
1506 static int tun_release(struct socket *sock)
1507 {
1508         if (sock->sk)
1509                 sock_put(sock->sk);
1510         return 0;
1511 }
1512 
1513 /* Ops structure to mimic raw sockets with tun */
1514 static const struct proto_ops tun_socket_ops = {
1515         .sendmsg = tun_sendmsg,
1516         .recvmsg = tun_recvmsg,
1517         .release = tun_release,
1518 };
1519 
1520 static struct proto tun_proto = {
1521         .name           = "tun",
1522         .owner          = THIS_MODULE,
1523         .obj_size       = sizeof(struct tun_file),
1524 };
1525 
1526 static int tun_flags(struct tun_struct *tun)
1527 {
1528         int flags = 0;
1529 
1530         if (tun->flags & TUN_TUN_DEV)
1531                 flags |= IFF_TUN;
1532         else
1533                 flags |= IFF_TAP;
1534 
1535         if (tun->flags & TUN_NO_PI)
1536                 flags |= IFF_NO_PI;
1537 
1538         /* This flag has no real effect.  We track the value for backwards
1539          * compatibility.
1540          */
1541         if (tun->flags & TUN_ONE_QUEUE)
1542                 flags |= IFF_ONE_QUEUE;
1543 
1544         if (tun->flags & TUN_VNET_HDR)
1545                 flags |= IFF_VNET_HDR;
1546 
1547         if (tun->flags & TUN_TAP_MQ)
1548                 flags |= IFF_MULTI_QUEUE;
1549 
1550         if (tun->flags & TUN_PERSIST)
1551                 flags |= IFF_PERSIST;
1552 
1553         return flags;
1554 }
1555 
1556 static ssize_t tun_show_flags(struct device *dev, struct device_attribute *attr,
1557                               char *buf)
1558 {
1559         struct tun_struct *tun = netdev_priv(to_net_dev(dev));
1560         return sprintf(buf, "0x%x\n", tun_flags(tun));
1561 }
1562 
1563 static ssize_t tun_show_owner(struct device *dev, struct device_attribute *attr,
1564                               char *buf)
1565 {
1566         struct tun_struct *tun = netdev_priv(to_net_dev(dev));
1567         return uid_valid(tun->owner)?
1568                 sprintf(buf, "%u\n",
1569                         from_kuid_munged(current_user_ns(), tun->owner)):
1570                 sprintf(buf, "-1\n");
1571 }
1572 
1573 static ssize_t tun_show_group(struct device *dev, struct device_attribute *attr,
1574                               char *buf)
1575 {
1576         struct tun_struct *tun = netdev_priv(to_net_dev(dev));
1577         return gid_valid(tun->group) ?
1578                 sprintf(buf, "%u\n",
1579                         from_kgid_munged(current_user_ns(), tun->group)):
1580                 sprintf(buf, "-1\n");
1581 }
1582 
1583 static DEVICE_ATTR(tun_flags, 0444, tun_show_flags, NULL);
1584 static DEVICE_ATTR(owner, 0444, tun_show_owner, NULL);
1585 static DEVICE_ATTR(group, 0444, tun_show_group, NULL);
1586 
1587 static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
1588 {
1589         struct tun_struct *tun;
1590         struct tun_file *tfile = file->private_data;
1591         struct net_device *dev;
1592         int err;
1593 
1594         if (tfile->detached)
1595                 return -EINVAL;
1596 
1597         dev = __dev_get_by_name(net, ifr->ifr_name);
1598         if (dev) {
1599                 if (ifr->ifr_flags & IFF_TUN_EXCL)
1600                         return -EBUSY;
1601                 if ((ifr->ifr_flags & IFF_TUN) && dev->netdev_ops == &tun_netdev_ops)
1602                         tun = netdev_priv(dev);
1603                 else if ((ifr->ifr_flags & IFF_TAP) && dev->netdev_ops == &tap_netdev_ops)
1604                         tun = netdev_priv(dev);
1605                 else
1606                         return -EINVAL;
1607 
1608                 if (!!(ifr->ifr_flags & IFF_MULTI_QUEUE) !=
1609                     !!(tun->flags & TUN_TAP_MQ))
1610                         return -EINVAL;
1611 
1612                 if (tun_not_capable(tun))
1613                         return -EPERM;
1614                 err = security_tun_dev_open(tun->security);
1615                 if (err < 0)
1616                         return err;
1617 
1618                 err = tun_attach(tun, file, ifr->ifr_flags & IFF_NOFILTER);
1619                 if (err < 0)
1620                         return err;
1621 
1622                 if (tun->flags & TUN_TAP_MQ &&
1623                     (tun->numqueues + tun->numdisabled > 1)) {
1624                         /* One or more queue has already been attached, no need
1625                          * to initialize the device again.
1626                          */
1627                         return 0;
1628                 }
1629         }
1630         else {
1631                 char *name;
1632                 unsigned long flags = 0;
1633                 int queues = ifr->ifr_flags & IFF_MULTI_QUEUE ?
1634                              MAX_TAP_QUEUES : 1;
1635 
1636                 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1637                         return -EPERM;
1638                 err = security_tun_dev_create();
1639                 if (err < 0)
1640                         return err;
1641 
1642                 /* Set dev type */
1643                 if (ifr->ifr_flags & IFF_TUN) {
1644                         /* TUN device */
1645                         flags |= TUN_TUN_DEV;
1646                         name = "tun%d";
1647                 } else if (ifr->ifr_flags & IFF_TAP) {
1648                         /* TAP device */
1649                         flags |= TUN_TAP_DEV;
1650                         name = "tap%d";
1651                 } else
1652                         return -EINVAL;
1653 
1654                 if (*ifr->ifr_name)
1655                         name = ifr->ifr_name;
1656 
1657                 dev = alloc_netdev_mqs(sizeof(struct tun_struct), name,
1658                                        tun_setup, queues, queues);
1659 
1660                 if (!dev)
1661                         return -ENOMEM;
1662 
1663                 dev_net_set(dev, net);
1664                 dev->rtnl_link_ops = &tun_link_ops;
1665                 dev->ifindex = tfile->ifindex;
1666 
1667                 tun = netdev_priv(dev);
1668                 tun->dev = dev;
1669                 tun->flags = flags;
1670                 tun->txflt.count = 0;
1671                 tun->vnet_hdr_sz = sizeof(struct virtio_net_hdr);
1672 
1673                 tun->filter_attached = false;
1674                 tun->sndbuf = tfile->socket.sk->sk_sndbuf;
1675 
1676                 spin_lock_init(&tun->lock);
1677 
1678                 err = security_tun_dev_alloc_security(&tun->security);
1679                 if (err < 0)
1680                         goto err_free_dev;
1681 
1682                 tun_net_init(dev);
1683                 tun_flow_init(tun);
1684 
1685                 dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST |
1686                                    TUN_USER_FEATURES | NETIF_F_HW_VLAN_CTAG_TX |
1687                                    NETIF_F_HW_VLAN_STAG_TX;
1688                 dev->features = dev->hw_features;
1689                 dev->vlan_features = dev->features &
1690                                      ~(NETIF_F_HW_VLAN_CTAG_TX |
1691                                        NETIF_F_HW_VLAN_STAG_TX);
1692 
1693                 INIT_LIST_HEAD(&tun->disabled);
1694                 err = tun_attach(tun, file, false);
1695                 if (err < 0)
1696                         goto err_free_flow;
1697 
1698                 err = register_netdevice(tun->dev);
1699                 if (err < 0)
1700                         goto err_detach;
1701 
1702                 if (device_create_file(&tun->dev->dev, &dev_attr_tun_flags) ||
1703                     device_create_file(&tun->dev->dev, &dev_attr_owner) ||
1704                     device_create_file(&tun->dev->dev, &dev_attr_group))
1705                         pr_err("Failed to create tun sysfs files\n");
1706         }
1707 
1708         netif_carrier_on(tun->dev);
1709 
1710         tun_debug(KERN_INFO, tun, "tun_set_iff\n");
1711 
1712         if (ifr->ifr_flags & IFF_NO_PI)
1713                 tun->flags |= TUN_NO_PI;
1714         else
1715                 tun->flags &= ~TUN_NO_PI;
1716 
1717         /* This flag has no real effect.  We track the value for backwards
1718          * compatibility.
1719          */
1720         if (ifr->ifr_flags & IFF_ONE_QUEUE)
1721                 tun->flags |= TUN_ONE_QUEUE;
1722         else
1723                 tun->flags &= ~TUN_ONE_QUEUE;
1724 
1725         if (ifr->ifr_flags & IFF_VNET_HDR)
1726                 tun->flags |= TUN_VNET_HDR;
1727         else
1728                 tun->flags &= ~TUN_VNET_HDR;
1729 
1730         if (ifr->ifr_flags & IFF_MULTI_QUEUE)
1731                 tun->flags |= TUN_TAP_MQ;
1732         else
1733                 tun->flags &= ~TUN_TAP_MQ;
1734 
1735         /* Make sure persistent devices do not get stuck in
1736          * xoff state.
1737          */
1738         if (netif_running(tun->dev))
1739                 netif_tx_wake_all_queues(tun->dev);
1740 
1741         strcpy(ifr->ifr_name, tun->dev->name);
1742         return 0;
1743 
1744 err_detach:
1745         tun_detach_all(dev);
1746 err_free_flow:
1747         tun_flow_uninit(tun);
1748         security_tun_dev_free_security(tun->security);
1749 err_free_dev:
1750         free_netdev(dev);
1751         return err;
1752 }
1753 
1754 static void tun_get_iff(struct net *net, struct tun_struct *tun,
1755                        struct ifreq *ifr)
1756 {
1757         tun_debug(KERN_INFO, tun, "tun_get_iff\n");
1758 
1759         strcpy(ifr->ifr_name, tun->dev->name);
1760 
1761         ifr->ifr_flags = tun_flags(tun);
1762 
1763 }
1764 
1765 /* This is like a cut-down ethtool ops, except done via tun fd so no
1766  * privs required. */
1767 static int set_offload(struct tun_struct *tun, unsigned long arg)
1768 {
1769         netdev_features_t features = 0;
1770 
1771         if (arg & TUN_F_CSUM) {
1772                 features |= NETIF_F_HW_CSUM;
1773                 arg &= ~TUN_F_CSUM;
1774 
1775                 if (arg & (TUN_F_TSO4|TUN_F_TSO6)) {
1776                         if (arg & TUN_F_TSO_ECN) {
1777                                 features |= NETIF_F_TSO_ECN;
1778                                 arg &= ~TUN_F_TSO_ECN;
1779                         }
1780                         if (arg & TUN_F_TSO4)
1781                                 features |= NETIF_F_TSO;
1782                         if (arg & TUN_F_TSO6)
1783                                 features |= NETIF_F_TSO6;
1784                         arg &= ~(TUN_F_TSO4|TUN_F_TSO6);
1785                 }
1786 
1787                 if (arg & TUN_F_UFO) {
1788                         features |= NETIF_F_UFO;
1789                         arg &= ~TUN_F_UFO;
1790                 }
1791         }
1792 
1793         /* This gives the user a way to test for new features in future by
1794          * trying to set them. */
1795         if (arg)
1796                 return -EINVAL;
1797 
1798         tun->set_features = features;
1799         netdev_update_features(tun->dev);
1800 
1801         return 0;
1802 }
1803 
1804 static void tun_detach_filter(struct tun_struct *tun, int n)
1805 {
1806         int i;
1807         struct tun_file *tfile;
1808 
1809         for (i = 0; i < n; i++) {
1810                 tfile = rtnl_dereference(tun->tfiles[i]);
1811                 sk_detach_filter(tfile->socket.sk);
1812         }
1813 
1814         tun->filter_attached = false;
1815 }
1816 
1817 static int tun_attach_filter(struct tun_struct *tun)
1818 {
1819         int i, ret = 0;
1820         struct tun_file *tfile;
1821 
1822         for (i = 0; i < tun->numqueues; i++) {
1823                 tfile = rtnl_dereference(tun->tfiles[i]);
1824                 ret = sk_attach_filter(&tun->fprog, tfile->socket.sk);
1825                 if (ret) {
1826                         tun_detach_filter(tun, i);
1827                         return ret;
1828                 }
1829         }
1830 
1831         tun->filter_attached = true;
1832         return ret;
1833 }
1834 
1835 static void tun_set_sndbuf(struct tun_struct *tun)
1836 {
1837         struct tun_file *tfile;
1838         int i;
1839 
1840         for (i = 0; i < tun->numqueues; i++) {
1841                 tfile = rtnl_dereference(tun->tfiles[i]);
1842                 tfile->socket.sk->sk_sndbuf = tun->sndbuf;
1843         }
1844 }
1845 
1846 static int tun_set_queue(struct file *file, struct ifreq *ifr)
1847 {
1848         struct tun_file *tfile = file->private_data;
1849         struct tun_struct *tun;
1850         int ret = 0;
1851 
1852         rtnl_lock();
1853 
1854         if (ifr->ifr_flags & IFF_ATTACH_QUEUE) {
1855                 tun = tfile->detached;
1856                 if (!tun) {
1857                         ret = -EINVAL;
1858                         goto unlock;
1859                 }
1860                 ret = security_tun_dev_attach_queue(tun->security);
1861                 if (ret < 0)
1862                         goto unlock;
1863                 ret = tun_attach(tun, file, false);
1864         } else if (ifr->ifr_flags & IFF_DETACH_QUEUE) {
1865                 tun = rtnl_dereference(tfile->tun);
1866                 if (!tun || !(tun->flags & TUN_TAP_MQ) || tfile->detached)
1867                         ret = -EINVAL;
1868                 else
1869                         __tun_detach(tfile, false);
1870         } else
1871                 ret = -EINVAL;
1872 
1873 unlock:
1874         rtnl_unlock();
1875         return ret;
1876 }
1877 
1878 static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
1879                             unsigned long arg, int ifreq_len)
1880 {
1881         struct tun_file *tfile = file->private_data;
1882         struct tun_struct *tun;
1883         void __user* argp = (void __user*)arg;
1884         struct ifreq ifr;
1885         kuid_t owner;
1886         kgid_t group;
1887         int sndbuf;
1888         int vnet_hdr_sz;
1889         unsigned int ifindex;
1890         int ret;
1891 
1892         if (cmd == TUNSETIFF || cmd == TUNSETQUEUE || _IOC_TYPE(cmd) == 0x89) {
1893                 if (copy_from_user(&ifr, argp, ifreq_len))
1894                         return -EFAULT;
1895         } else {
1896                 memset(&ifr, 0, sizeof(ifr));
1897         }
1898         if (cmd == TUNGETFEATURES) {
1899                 /* Currently this just means: "what IFF flags are valid?".
1900                  * This is needed because we never checked for invalid flags on
1901                  * TUNSETIFF. */
1902                 return put_user(IFF_TUN | IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE |
1903                                 IFF_VNET_HDR | IFF_MULTI_QUEUE,
1904                                 (unsigned int __user*)argp);
1905         } else if (cmd == TUNSETQUEUE)
1906                 return tun_set_queue(file, &ifr);
1907 
1908         ret = 0;
1909         rtnl_lock();
1910 
1911         tun = __tun_get(tfile);
1912         if (cmd == TUNSETIFF && !tun) {
1913                 ifr.ifr_name[IFNAMSIZ-1] = '\0';
1914 
1915                 ret = tun_set_iff(tfile->net, file, &ifr);
1916 
1917                 if (ret)
1918                         goto unlock;
1919 
1920                 if (copy_to_user(argp, &ifr, ifreq_len))
1921                         ret = -EFAULT;
1922                 goto unlock;
1923         }
1924         if (cmd == TUNSETIFINDEX) {
1925                 ret = -EPERM;
1926                 if (tun)
1927                         goto unlock;
1928 
1929                 ret = -EFAULT;
1930                 if (copy_from_user(&ifindex, argp, sizeof(ifindex)))
1931                         goto unlock;
1932 
1933                 ret = 0;
1934                 tfile->ifindex = ifindex;
1935                 goto unlock;
1936         }
1937 
1938         ret = -EBADFD;
1939         if (!tun)
1940                 goto unlock;
1941 
1942         tun_debug(KERN_INFO, tun, "tun_chr_ioctl cmd %u\n", cmd);
1943 
1944         ret = 0;
1945         switch (cmd) {
1946         case TUNGETIFF:
1947                 tun_get_iff(current->nsproxy->net_ns, tun, &ifr);
1948 
1949                 if (tfile->detached)
1950                         ifr.ifr_flags |= IFF_DETACH_QUEUE;
1951                 if (!tfile->socket.sk->sk_filter)
1952                         ifr.ifr_flags |= IFF_NOFILTER;
1953 
1954                 if (copy_to_user(argp, &ifr, ifreq_len))
1955                         ret = -EFAULT;
1956                 break;
1957 
1958         case TUNSETNOCSUM:
1959                 /* Disable/Enable checksum */
1960 
1961                 /* [unimplemented] */
1962                 tun_debug(KERN_INFO, tun, "ignored: set checksum %s\n",
1963                           arg ? "disabled" : "enabled");
1964                 break;
1965 
1966         case TUNSETPERSIST:
1967                 /* Disable/Enable persist mode. Keep an extra reference to the
1968                  * module to prevent the module being unprobed.
1969                  */
1970                 if (arg && !(tun->flags & TUN_PERSIST)) {
1971                         tun->flags |= TUN_PERSIST;
1972                         __module_get(THIS_MODULE);
1973                 }
1974                 if (!arg && (tun->flags & TUN_PERSIST)) {
1975                         tun->flags &= ~TUN_PERSIST;
1976                         module_put(THIS_MODULE);
1977                 }
1978 
1979                 tun_debug(KERN_INFO, tun, "persist %s\n",
1980                           arg ? "enabled" : "disabled");
1981                 break;
1982 
1983         case TUNSETOWNER:
1984                 /* Set owner of the device */
1985                 owner = make_kuid(current_user_ns(), arg);
1986                 if (!uid_valid(owner)) {
1987                         ret = -EINVAL;
1988                         break;
1989                 }
1990                 tun->owner = owner;
1991                 tun_debug(KERN_INFO, tun, "owner set to %u\n",
1992                           from_kuid(&init_user_ns, tun->owner));
1993                 break;
1994 
1995         case TUNSETGROUP:
1996                 /* Set group of the device */
1997                 group = make_kgid(current_user_ns(), arg);
1998                 if (!gid_valid(group)) {
1999                         ret = -EINVAL;
2000                         break;
2001                 }
2002                 tun->group = group;
2003                 tun_debug(KERN_INFO, tun, "group set to %u\n",
2004                           from_kgid(&init_user_ns, tun->group));
2005                 break;
2006 
2007         case TUNSETLINK:
2008                 /* Only allow setting the type when the interface is down */
2009                 if (tun->dev->flags & IFF_UP) {
2010                         tun_debug(KERN_INFO, tun,
2011                                   "Linktype set failed because interface is up\n");
2012                         ret = -EBUSY;
2013                 } else {
2014                         tun->dev->type = (int) arg;
2015                         tun_debug(KERN_INFO, tun, "linktype set to %d\n",
2016                                   tun->dev->type);
2017                         ret = 0;
2018                 }
2019                 break;
2020 
2021 #ifdef TUN_DEBUG
2022         case TUNSETDEBUG:
2023                 tun->debug = arg;
2024                 break;
2025 #endif
2026         case TUNSETOFFLOAD:
2027                 ret = set_offload(tun, arg);
2028                 break;
2029 
2030         case TUNSETTXFILTER:
2031                 /* Can be set only for TAPs */
2032                 ret = -EINVAL;
2033                 if ((tun->flags & TUN_TYPE_MASK) != TUN_TAP_DEV)
2034                         break;
2035                 ret = update_filter(&tun->txflt, (void __user *)arg);
2036                 break;
2037 
2038         case SIOCGIFHWADDR:
2039                 /* Get hw address */
2040                 memcpy(ifr.ifr_hwaddr.sa_data, tun->dev->dev_addr, ETH_ALEN);
2041                 ifr.ifr_hwaddr.sa_family = tun->dev->type;
2042                 if (copy_to_user(argp, &ifr, ifreq_len))
2043                         ret = -EFAULT;
2044                 break;
2045 
2046         case SIOCSIFHWADDR:
2047                 /* Set hw address */
2048                 tun_debug(KERN_DEBUG, tun, "set hw address: %pM\n",
2049                           ifr.ifr_hwaddr.sa_data);
2050 
2051                 ret = dev_set_mac_address(tun->dev, &ifr.ifr_hwaddr);
2052                 break;
2053 
2054         case TUNGETSNDBUF:
2055                 sndbuf = tfile->socket.sk->sk_sndbuf;
2056                 if (copy_to_user(argp, &sndbuf, sizeof(sndbuf)))
2057                         ret = -EFAULT;
2058                 break;
2059 
2060         case TUNSETSNDBUF:
2061                 if (copy_from_user(&sndbuf, argp, sizeof(sndbuf))) {
2062                         ret = -EFAULT;
2063                         break;
2064                 }
2065 
2066                 tun->sndbuf = sndbuf;
2067                 tun_set_sndbuf(tun);
2068                 break;
2069 
2070         case TUNGETVNETHDRSZ:
2071                 vnet_hdr_sz = tun->vnet_hdr_sz;
2072                 if (copy_to_user(argp, &vnet_hdr_sz, sizeof(vnet_hdr_sz)))
2073                         ret = -EFAULT;
2074                 break;
2075 
2076         case TUNSETVNETHDRSZ:
2077                 if (copy_from_user(&vnet_hdr_sz, argp, sizeof(vnet_hdr_sz))) {
2078                         ret = -EFAULT;
2079                         break;
2080                 }
2081                 if (vnet_hdr_sz < (int)sizeof(struct virtio_net_hdr)) {
2082                         ret = -EINVAL;
2083                         break;
2084                 }
2085 
2086                 tun->vnet_hdr_sz = vnet_hdr_sz;
2087                 break;
2088 
2089         case TUNATTACHFILTER:
2090                 /* Can be set only for TAPs */
2091                 ret = -EINVAL;
2092                 if ((tun->flags & TUN_TYPE_MASK) != TUN_TAP_DEV)
2093                         break;
2094                 ret = -EFAULT;
2095                 if (copy_from_user(&tun->fprog, argp, sizeof(tun->fprog)))
2096                         break;
2097 
2098                 ret = tun_attach_filter(tun);
2099                 break;
2100 
2101         case TUNDETACHFILTER:
2102                 /* Can be set only for TAPs */
2103                 ret = -EINVAL;
2104                 if ((tun->flags & TUN_TYPE_MASK) != TUN_TAP_DEV)
2105                         break;
2106                 ret = 0;
2107                 tun_detach_filter(tun, tun->numqueues);
2108                 break;
2109 
2110         case TUNGETFILTER:
2111                 ret = -EINVAL;
2112                 if ((tun->flags & TUN_TYPE_MASK) != TUN_TAP_DEV)
2113                         break;
2114                 ret = -EFAULT;
2115                 if (copy_to_user(argp, &tun->fprog, sizeof(tun->fprog)))
2116                         break;
2117                 ret = 0;
2118                 break;
2119 
2120         default:
2121                 ret = -EINVAL;
2122                 break;
2123         }
2124 
2125 unlock:
2126         rtnl_unlock();
2127         if (tun)
2128                 tun_put(tun);
2129         return ret;
2130 }
2131 
2132 static long tun_chr_ioctl(struct file *file,
2133                           unsigned int cmd, unsigned long arg)
2134 {
2135         return __tun_chr_ioctl(file, cmd, arg, sizeof (struct ifreq));
2136 }
2137 
2138 #ifdef CONFIG_COMPAT
2139 static long tun_chr_compat_ioctl(struct file *file,
2140                          unsigned int cmd, unsigned long arg)
2141 {
2142         switch (cmd) {
2143         case TUNSETIFF:
2144         case TUNGETIFF:
2145         case TUNSETTXFILTER:
2146         case TUNGETSNDBUF:
2147         case TUNSETSNDBUF:
2148         case SIOCGIFHWADDR:
2149         case SIOCSIFHWADDR:
2150                 arg = (unsigned long)compat_ptr(arg);
2151                 break;
2152         default:
2153                 arg = (compat_ulong_t)arg;
2154                 break;
2155         }
2156 
2157         /*
2158          * compat_ifreq is shorter than ifreq, so we must not access beyond
2159          * the end of that structure. All fields that are used in this
2160          * driver are compatible though, we don't need to convert the
2161          * contents.
2162          */
2163         return __tun_chr_ioctl(file, cmd, arg, sizeof(struct compat_ifreq));
2164 }
2165 #endif /* CONFIG_COMPAT */
2166 
2167 static int tun_chr_fasync(int fd, struct file *file, int on)
2168 {
2169         struct tun_file *tfile = file->private_data;
2170         int ret;
2171 
2172         if ((ret = fasync_helper(fd, file, on, &tfile->fasync)) < 0)
2173                 goto out;
2174 
2175         if (on) {
2176                 ret = __f_setown(file, task_pid(current), PIDTYPE_PID, 0);
2177                 if (ret)
2178                         goto out;
2179                 tfile->flags |= TUN_FASYNC;
2180         } else
2181                 tfile->flags &= ~TUN_FASYNC;
2182         ret = 0;
2183 out:
2184         return ret;
2185 }
2186 
2187 static int tun_chr_open(struct inode *inode, struct file * file)
2188 {
2189         struct tun_file *tfile;
2190 
2191         DBG1(KERN_INFO, "tunX: tun_chr_open\n");
2192 
2193         tfile = (struct tun_file *)sk_alloc(&init_net, AF_UNSPEC, GFP_KERNEL,
2194                                             &tun_proto);
2195         if (!tfile)
2196                 return -ENOMEM;
2197         RCU_INIT_POINTER(tfile->tun, NULL);
2198         tfile->net = get_net(current->nsproxy->net_ns);
2199         tfile->flags = 0;
2200         tfile->ifindex = 0;
2201 
2202         rcu_assign_pointer(tfile->socket.wq, &tfile->wq);
2203         init_waitqueue_head(&tfile->wq.wait);
2204 
2205         tfile->socket.file = file;
2206         tfile->socket.ops = &tun_socket_ops;
2207 
2208         sock_init_data(&tfile->socket, &tfile->sk);
2209         sk_change_net(&tfile->sk, tfile->net);
2210 
2211         tfile->sk.sk_write_space = tun_sock_write_space;
2212         tfile->sk.sk_sndbuf = INT_MAX;
2213 
2214         file->private_data = tfile;
2215         set_bit(SOCK_EXTERNALLY_ALLOCATED, &tfile->socket.flags);
2216         INIT_LIST_HEAD(&tfile->next);
2217 
2218         sock_set_flag(&tfile->sk, SOCK_ZEROCOPY);
2219 
2220         return 0;
2221 }
2222 
2223 static int tun_chr_close(struct inode *inode, struct file *file)
2224 {
2225         struct tun_file *tfile = file->private_data;
2226         struct net *net = tfile->net;
2227 
2228         tun_detach(tfile, true);
2229         put_net(net);
2230 
2231         return 0;
2232 }
2233 
2234 #ifdef CONFIG_PROC_FS
2235 static int tun_chr_show_fdinfo(struct seq_file *m, struct file *f)
2236 {
2237         struct tun_struct *tun;
2238         struct ifreq ifr;
2239 
2240         memset(&ifr, 0, sizeof(ifr));
2241 
2242         rtnl_lock();
2243         tun = tun_get(f);
2244         if (tun)
2245                 tun_get_iff(current->nsproxy->net_ns, tun, &ifr);
2246         rtnl_unlock();
2247 
2248         if (tun)
2249                 tun_put(tun);
2250 
2251         return seq_printf(m, "iff:\t%s\n", ifr.ifr_name);
2252 }
2253 #endif
2254 
2255 static const struct file_operations tun_fops = {
2256         .owner  = THIS_MODULE,
2257         .llseek = no_llseek,
2258         .read  = do_sync_read,
2259         .aio_read  = tun_chr_aio_read,
2260         .write = do_sync_write,
2261         .aio_write = tun_chr_aio_write,
2262         .poll   = tun_chr_poll,
2263         .unlocked_ioctl = tun_chr_ioctl,
2264 #ifdef CONFIG_COMPAT
2265         .compat_ioctl = tun_chr_compat_ioctl,
2266 #endif
2267         .open   = tun_chr_open,
2268         .release = tun_chr_close,
2269         .fasync = tun_chr_fasync,
2270 #ifdef CONFIG_PROC_FS
2271         .show_fdinfo = tun_chr_show_fdinfo,
2272 #endif
2273 };
2274 
2275 static struct miscdevice tun_miscdev = {
2276         .minor = TUN_MINOR,
2277         .name = "tun",
2278         .nodename = "net/tun",
2279         .fops = &tun_fops,
2280 };
2281 
2282 /* ethtool interface */
2283 
2284 static int tun_get_settings(struct net_device *dev, struct ethtool_cmd *cmd)
2285 {
2286         cmd->supported          = 0;
2287         cmd->advertising        = 0;
2288         ethtool_cmd_speed_set(cmd, SPEED_10);
2289         cmd->duplex             = DUPLEX_FULL;
2290         cmd->port               = PORT_TP;
2291         cmd->phy_address        = 0;
2292         cmd->transceiver        = XCVR_INTERNAL;
2293         cmd->autoneg            = AUTONEG_DISABLE;
2294         cmd->maxtxpkt           = 0;
2295         cmd->maxrxpkt           = 0;
2296         return 0;
2297 }
2298 
2299 static void tun_get_drvinfo(struct net_device *dev, struct ethtool_drvinfo *info)
2300 {
2301         struct tun_struct *tun = netdev_priv(dev);
2302 
2303         strlcpy(info->driver, DRV_NAME, sizeof(info->driver));
2304         strlcpy(info->version, DRV_VERSION, sizeof(info->version));
2305 
2306         switch (tun->flags & TUN_TYPE_MASK) {
2307         case TUN_TUN_DEV:
2308                 strlcpy(info->bus_info, "tun", sizeof(info->bus_info));
2309                 break;
2310         case TUN_TAP_DEV:
2311                 strlcpy(info->bus_info, "tap", sizeof(info->bus_info));
2312                 break;
2313         }
2314 }
2315 
2316 static u32 tun_get_msglevel(struct net_device *dev)
2317 {
2318 #ifdef TUN_DEBUG
2319         struct tun_struct *tun = netdev_priv(dev);
2320         return tun->debug;
2321 #else
2322         return -EOPNOTSUPP;
2323 #endif
2324 }
2325 
2326 static void tun_set_msglevel(struct net_device *dev, u32 value)
2327 {
2328 #ifdef TUN_DEBUG
2329         struct tun_struct *tun = netdev_priv(dev);
2330         tun->debug = value;
2331 #endif
2332 }
2333 
2334 static const struct ethtool_ops tun_ethtool_ops = {
2335         .get_settings   = tun_get_settings,
2336         .get_drvinfo    = tun_get_drvinfo,
2337         .get_msglevel   = tun_get_msglevel,
2338         .set_msglevel   = tun_set_msglevel,
2339         .get_link       = ethtool_op_get_link,
2340         .get_ts_info    = ethtool_op_get_ts_info,
2341 };
2342 
2343 
2344 static int __init tun_init(void)
2345 {
2346         int ret = 0;
2347 
2348         pr_info("%s, %s\n", DRV_DESCRIPTION, DRV_VERSION);
2349         pr_info("%s\n", DRV_COPYRIGHT);
2350 
2351         ret = rtnl_link_register(&tun_link_ops);
2352         if (ret) {
2353                 pr_err("Can't register link_ops\n");
2354                 goto err_linkops;
2355         }
2356 
2357         ret = misc_register(&tun_miscdev);
2358         if (ret) {
2359                 pr_err("Can't register misc device %d\n", TUN_MINOR);
2360                 goto err_misc;
2361         }
2362         return  0;
2363 err_misc:
2364         rtnl_link_unregister(&tun_link_ops);
2365 err_linkops:
2366         return ret;
2367 }
2368 
2369 static void tun_cleanup(void)
2370 {
2371         misc_deregister(&tun_miscdev);
2372         rtnl_link_unregister(&tun_link_ops);
2373 }
2374 
2375 /* Get an underlying socket object from tun file.  Returns error unless file is
2376  * attached to a device.  The returned object works like a packet socket, it
2377  * can be used for sock_sendmsg/sock_recvmsg.  The caller is responsible for
2378  * holding a reference to the file for as long as the socket is in use. */
2379 struct socket *tun_get_socket(struct file *file)
2380 {
2381         struct tun_file *tfile;
2382         if (file->f_op != &tun_fops)
2383                 return ERR_PTR(-EINVAL);
2384         tfile = file->private_data;
2385         if (!tfile)
2386                 return ERR_PTR(-EBADFD);
2387         return &tfile->socket;
2388 }
2389 EXPORT_SYMBOL_GPL(tun_get_socket);
2390 
2391 module_init(tun_init);
2392 module_exit(tun_cleanup);
2393 MODULE_DESCRIPTION(DRV_DESCRIPTION);
2394 MODULE_AUTHOR(DRV_COPYRIGHT);
2395 MODULE_LICENSE("GPL");
2396 MODULE_ALIAS_MISCDEV(TUN_MINOR);
2397 MODULE_ALIAS("devname:net/tun");
2398 

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