Version:  2.0.40 2.2.26 2.4.37 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 3.16

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                 tfile->socket.sk->sk_data_ready(tfile->socket.sk);
502                 RCU_INIT_POINTER(tfile->tun, NULL);
503                 --tun->numqueues;
504         }
505         list_for_each_entry(tfile, &tun->disabled, next) {
506                 tfile->socket.sk->sk_data_ready(tfile->socket.sk);
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         tfile->socket.sk->sk_data_ready(tfile->socket.sk);
811 
812         rcu_read_unlock();
813         return NETDEV_TX_OK;
814 
815 drop:
816         dev->stats.tx_dropped++;
817         skb_tx_error(skb);
818         kfree_skb(skb);
819         rcu_read_unlock();
820         return NETDEV_TX_OK;
821 }
822 
823 static void tun_net_mclist(struct net_device *dev)
824 {
825         /*
826          * This callback is supposed to deal with mc filter in
827          * _rx_ path and has nothing to do with the _tx_ path.
828          * In rx path we always accept everything userspace gives us.
829          */
830 }
831 
832 #define MIN_MTU 68
833 #define MAX_MTU 65535
834 
835 static int
836 tun_net_change_mtu(struct net_device *dev, int new_mtu)
837 {
838         if (new_mtu < MIN_MTU || new_mtu + dev->hard_header_len > MAX_MTU)
839                 return -EINVAL;
840         dev->mtu = new_mtu;
841         return 0;
842 }
843 
844 static netdev_features_t tun_net_fix_features(struct net_device *dev,
845         netdev_features_t features)
846 {
847         struct tun_struct *tun = netdev_priv(dev);
848 
849         return (features & tun->set_features) | (features & ~TUN_USER_FEATURES);
850 }
851 #ifdef CONFIG_NET_POLL_CONTROLLER
852 static void tun_poll_controller(struct net_device *dev)
853 {
854         /*
855          * Tun only receives frames when:
856          * 1) the char device endpoint gets data from user space
857          * 2) the tun socket gets a sendmsg call from user space
858          * Since both of those are synchronous operations, we are guaranteed
859          * never to have pending data when we poll for it
860          * so there is nothing to do here but return.
861          * We need this though so netpoll recognizes us as an interface that
862          * supports polling, which enables bridge devices in virt setups to
863          * still use netconsole
864          */
865         return;
866 }
867 #endif
868 static const struct net_device_ops tun_netdev_ops = {
869         .ndo_uninit             = tun_net_uninit,
870         .ndo_open               = tun_net_open,
871         .ndo_stop               = tun_net_close,
872         .ndo_start_xmit         = tun_net_xmit,
873         .ndo_change_mtu         = tun_net_change_mtu,
874         .ndo_fix_features       = tun_net_fix_features,
875         .ndo_select_queue       = tun_select_queue,
876 #ifdef CONFIG_NET_POLL_CONTROLLER
877         .ndo_poll_controller    = tun_poll_controller,
878 #endif
879 };
880 
881 static const struct net_device_ops tap_netdev_ops = {
882         .ndo_uninit             = tun_net_uninit,
883         .ndo_open               = tun_net_open,
884         .ndo_stop               = tun_net_close,
885         .ndo_start_xmit         = tun_net_xmit,
886         .ndo_change_mtu         = tun_net_change_mtu,
887         .ndo_fix_features       = tun_net_fix_features,
888         .ndo_set_rx_mode        = tun_net_mclist,
889         .ndo_set_mac_address    = eth_mac_addr,
890         .ndo_validate_addr      = eth_validate_addr,
891         .ndo_select_queue       = tun_select_queue,
892 #ifdef CONFIG_NET_POLL_CONTROLLER
893         .ndo_poll_controller    = tun_poll_controller,
894 #endif
895 };
896 
897 static void tun_flow_init(struct tun_struct *tun)
898 {
899         int i;
900 
901         for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++)
902                 INIT_HLIST_HEAD(&tun->flows[i]);
903 
904         tun->ageing_time = TUN_FLOW_EXPIRE;
905         setup_timer(&tun->flow_gc_timer, tun_flow_cleanup, (unsigned long)tun);
906         mod_timer(&tun->flow_gc_timer,
907                   round_jiffies_up(jiffies + tun->ageing_time));
908 }
909 
910 static void tun_flow_uninit(struct tun_struct *tun)
911 {
912         del_timer_sync(&tun->flow_gc_timer);
913         tun_flow_flush(tun);
914 }
915 
916 /* Initialize net device. */
917 static void tun_net_init(struct net_device *dev)
918 {
919         struct tun_struct *tun = netdev_priv(dev);
920 
921         switch (tun->flags & TUN_TYPE_MASK) {
922         case TUN_TUN_DEV:
923                 dev->netdev_ops = &tun_netdev_ops;
924 
925                 /* Point-to-Point TUN Device */
926                 dev->hard_header_len = 0;
927                 dev->addr_len = 0;
928                 dev->mtu = 1500;
929 
930                 /* Zero header length */
931                 dev->type = ARPHRD_NONE;
932                 dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
933                 dev->tx_queue_len = TUN_READQ_SIZE;  /* We prefer our own queue length */
934                 break;
935 
936         case TUN_TAP_DEV:
937                 dev->netdev_ops = &tap_netdev_ops;
938                 /* Ethernet TAP Device */
939                 ether_setup(dev);
940                 dev->priv_flags &= ~IFF_TX_SKB_SHARING;
941                 dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
942 
943                 eth_hw_addr_random(dev);
944 
945                 dev->tx_queue_len = TUN_READQ_SIZE;  /* We prefer our own queue length */
946                 break;
947         }
948 }
949 
950 /* Character device part */
951 
952 /* Poll */
953 static unsigned int tun_chr_poll(struct file *file, poll_table *wait)
954 {
955         struct tun_file *tfile = file->private_data;
956         struct tun_struct *tun = __tun_get(tfile);
957         struct sock *sk;
958         unsigned int mask = 0;
959 
960         if (!tun)
961                 return POLLERR;
962 
963         sk = tfile->socket.sk;
964 
965         tun_debug(KERN_INFO, tun, "tun_chr_poll\n");
966 
967         poll_wait(file, sk_sleep(sk), wait);
968 
969         if (!skb_queue_empty(&sk->sk_receive_queue))
970                 mask |= POLLIN | POLLRDNORM;
971 
972         if (sock_writeable(sk) ||
973             (!test_and_set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags) &&
974              sock_writeable(sk)))
975                 mask |= POLLOUT | POLLWRNORM;
976 
977         if (tun->dev->reg_state != NETREG_REGISTERED)
978                 mask = POLLERR;
979 
980         tun_put(tun);
981         return mask;
982 }
983 
984 /* prepad is the amount to reserve at front.  len is length after that.
985  * linear is a hint as to how much to copy (usually headers). */
986 static struct sk_buff *tun_alloc_skb(struct tun_file *tfile,
987                                      size_t prepad, size_t len,
988                                      size_t linear, int noblock)
989 {
990         struct sock *sk = tfile->socket.sk;
991         struct sk_buff *skb;
992         int err;
993 
994         /* Under a page?  Don't bother with paged skb. */
995         if (prepad + len < PAGE_SIZE || !linear)
996                 linear = len;
997 
998         skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
999                                    &err, 0);
1000         if (!skb)
1001                 return ERR_PTR(err);
1002 
1003         skb_reserve(skb, prepad);
1004         skb_put(skb, linear);
1005         skb->data_len = len - linear;
1006         skb->len += len - linear;
1007 
1008         return skb;
1009 }
1010 
1011 /* Get packet from user space buffer */
1012 static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
1013                             void *msg_control, const struct iovec *iv,
1014                             size_t total_len, size_t count, int noblock)
1015 {
1016         struct tun_pi pi = { 0, cpu_to_be16(ETH_P_IP) };
1017         struct sk_buff *skb;
1018         size_t len = total_len, align = NET_SKB_PAD, linear;
1019         struct virtio_net_hdr gso = { 0 };
1020         int good_linear;
1021         int offset = 0;
1022         int copylen;
1023         bool zerocopy = false;
1024         int err;
1025         u32 rxhash;
1026 
1027         if (!(tun->flags & TUN_NO_PI)) {
1028                 if (len < sizeof(pi))
1029                         return -EINVAL;
1030                 len -= sizeof(pi);
1031 
1032                 if (memcpy_fromiovecend((void *)&pi, iv, 0, sizeof(pi)))
1033                         return -EFAULT;
1034                 offset += sizeof(pi);
1035         }
1036 
1037         if (tun->flags & TUN_VNET_HDR) {
1038                 if (len < tun->vnet_hdr_sz)
1039                         return -EINVAL;
1040                 len -= tun->vnet_hdr_sz;
1041 
1042                 if (memcpy_fromiovecend((void *)&gso, iv, offset, sizeof(gso)))
1043                         return -EFAULT;
1044 
1045                 if ((gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
1046                     gso.csum_start + gso.csum_offset + 2 > gso.hdr_len)
1047                         gso.hdr_len = gso.csum_start + gso.csum_offset + 2;
1048 
1049                 if (gso.hdr_len > len)
1050                         return -EINVAL;
1051                 offset += tun->vnet_hdr_sz;
1052         }
1053 
1054         if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV) {
1055                 align += NET_IP_ALIGN;
1056                 if (unlikely(len < ETH_HLEN ||
1057                              (gso.hdr_len && gso.hdr_len < ETH_HLEN)))
1058                         return -EINVAL;
1059         }
1060 
1061         good_linear = SKB_MAX_HEAD(align);
1062 
1063         if (msg_control) {
1064                 /* There are 256 bytes to be copied in skb, so there is
1065                  * enough room for skb expand head in case it is used.
1066                  * The rest of the buffer is mapped from userspace.
1067                  */
1068                 copylen = gso.hdr_len ? gso.hdr_len : GOODCOPY_LEN;
1069                 if (copylen > good_linear)
1070                         copylen = good_linear;
1071                 linear = copylen;
1072                 if (iov_pages(iv, offset + copylen, count) <= MAX_SKB_FRAGS)
1073                         zerocopy = true;
1074         }
1075 
1076         if (!zerocopy) {
1077                 copylen = len;
1078                 if (gso.hdr_len > good_linear)
1079                         linear = good_linear;
1080                 else
1081                         linear = gso.hdr_len;
1082         }
1083 
1084         skb = tun_alloc_skb(tfile, align, copylen, linear, noblock);
1085         if (IS_ERR(skb)) {
1086                 if (PTR_ERR(skb) != -EAGAIN)
1087                         tun->dev->stats.rx_dropped++;
1088                 return PTR_ERR(skb);
1089         }
1090 
1091         if (zerocopy)
1092                 err = zerocopy_sg_from_iovec(skb, iv, offset, count);
1093         else {
1094                 err = skb_copy_datagram_from_iovec(skb, 0, iv, offset, len);
1095                 if (!err && msg_control) {
1096                         struct ubuf_info *uarg = msg_control;
1097                         uarg->callback(uarg, false);
1098                 }
1099         }
1100 
1101         if (err) {
1102                 tun->dev->stats.rx_dropped++;
1103                 kfree_skb(skb);
1104                 return -EFAULT;
1105         }
1106 
1107         if (gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
1108                 if (!skb_partial_csum_set(skb, gso.csum_start,
1109                                           gso.csum_offset)) {
1110                         tun->dev->stats.rx_frame_errors++;
1111                         kfree_skb(skb);
1112                         return -EINVAL;
1113                 }
1114         }
1115 
1116         switch (tun->flags & TUN_TYPE_MASK) {
1117         case TUN_TUN_DEV:
1118                 if (tun->flags & TUN_NO_PI) {
1119                         switch (skb->data[0] & 0xf0) {
1120                         case 0x40:
1121                                 pi.proto = htons(ETH_P_IP);
1122                                 break;
1123                         case 0x60:
1124                                 pi.proto = htons(ETH_P_IPV6);
1125                                 break;
1126                         default:
1127                                 tun->dev->stats.rx_dropped++;
1128                                 kfree_skb(skb);
1129                                 return -EINVAL;
1130                         }
1131                 }
1132 
1133                 skb_reset_mac_header(skb);
1134                 skb->protocol = pi.proto;
1135                 skb->dev = tun->dev;
1136                 break;
1137         case TUN_TAP_DEV:
1138                 skb->protocol = eth_type_trans(skb, tun->dev);
1139                 break;
1140         }
1141 
1142         if (gso.gso_type != VIRTIO_NET_HDR_GSO_NONE) {
1143                 pr_debug("GSO!\n");
1144                 switch (gso.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
1145                 case VIRTIO_NET_HDR_GSO_TCPV4:
1146                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
1147                         break;
1148                 case VIRTIO_NET_HDR_GSO_TCPV6:
1149                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
1150                         break;
1151                 case VIRTIO_NET_HDR_GSO_UDP:
1152                         skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1153                         break;
1154                 default:
1155                         tun->dev->stats.rx_frame_errors++;
1156                         kfree_skb(skb);
1157                         return -EINVAL;
1158                 }
1159 
1160                 if (gso.gso_type & VIRTIO_NET_HDR_GSO_ECN)
1161                         skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
1162 
1163                 skb_shinfo(skb)->gso_size = gso.gso_size;
1164                 if (skb_shinfo(skb)->gso_size == 0) {
1165                         tun->dev->stats.rx_frame_errors++;
1166                         kfree_skb(skb);
1167                         return -EINVAL;
1168                 }
1169 
1170                 /* Header must be checked, and gso_segs computed. */
1171                 skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
1172                 skb_shinfo(skb)->gso_segs = 0;
1173         }
1174 
1175         /* copy skb_ubuf_info for callback when skb has no error */
1176         if (zerocopy) {
1177                 skb_shinfo(skb)->destructor_arg = msg_control;
1178                 skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
1179                 skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
1180         }
1181 
1182         skb_reset_network_header(skb);
1183         skb_probe_transport_header(skb, 0);
1184 
1185         rxhash = skb_get_hash(skb);
1186         netif_rx_ni(skb);
1187 
1188         tun->dev->stats.rx_packets++;
1189         tun->dev->stats.rx_bytes += len;
1190 
1191         tun_flow_update(tun, rxhash, tfile);
1192         return total_len;
1193 }
1194 
1195 static ssize_t tun_chr_aio_write(struct kiocb *iocb, const struct iovec *iv,
1196                               unsigned long count, loff_t pos)
1197 {
1198         struct file *file = iocb->ki_filp;
1199         struct tun_struct *tun = tun_get(file);
1200         struct tun_file *tfile = file->private_data;
1201         ssize_t result;
1202 
1203         if (!tun)
1204                 return -EBADFD;
1205 
1206         tun_debug(KERN_INFO, tun, "tun_chr_write %ld\n", count);
1207 
1208         result = tun_get_user(tun, tfile, NULL, iv, iov_length(iv, count),
1209                               count, file->f_flags & O_NONBLOCK);
1210 
1211         tun_put(tun);
1212         return result;
1213 }
1214 
1215 /* Put packet to the user space buffer */
1216 static ssize_t tun_put_user(struct tun_struct *tun,
1217                             struct tun_file *tfile,
1218                             struct sk_buff *skb,
1219                             const struct iovec *iv, int len)
1220 {
1221         struct tun_pi pi = { 0, skb->protocol };
1222         ssize_t total = 0;
1223         int vlan_offset = 0, copied;
1224 
1225         if (!(tun->flags & TUN_NO_PI)) {
1226                 if ((len -= sizeof(pi)) < 0)
1227                         return -EINVAL;
1228 
1229                 if (len < skb->len) {
1230                         /* Packet will be striped */
1231                         pi.flags |= TUN_PKT_STRIP;
1232                 }
1233 
1234                 if (memcpy_toiovecend(iv, (void *) &pi, 0, sizeof(pi)))
1235                         return -EFAULT;
1236                 total += sizeof(pi);
1237         }
1238 
1239         if (tun->flags & TUN_VNET_HDR) {
1240                 struct virtio_net_hdr gso = { 0 }; /* no info leak */
1241                 if ((len -= tun->vnet_hdr_sz) < 0)
1242                         return -EINVAL;
1243 
1244                 if (skb_is_gso(skb)) {
1245                         struct skb_shared_info *sinfo = skb_shinfo(skb);
1246 
1247                         /* This is a hint as to how much should be linear. */
1248                         gso.hdr_len = skb_headlen(skb);
1249                         gso.gso_size = sinfo->gso_size;
1250                         if (sinfo->gso_type & SKB_GSO_TCPV4)
1251                                 gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
1252                         else if (sinfo->gso_type & SKB_GSO_TCPV6)
1253                                 gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
1254                         else if (sinfo->gso_type & SKB_GSO_UDP)
1255                                 gso.gso_type = VIRTIO_NET_HDR_GSO_UDP;
1256                         else {
1257                                 pr_err("unexpected GSO type: "
1258                                        "0x%x, gso_size %d, hdr_len %d\n",
1259                                        sinfo->gso_type, gso.gso_size,
1260                                        gso.hdr_len);
1261                                 print_hex_dump(KERN_ERR, "tun: ",
1262                                                DUMP_PREFIX_NONE,
1263                                                16, 1, skb->head,
1264                                                min((int)gso.hdr_len, 64), true);
1265                                 WARN_ON_ONCE(1);
1266                                 return -EINVAL;
1267                         }
1268                         if (sinfo->gso_type & SKB_GSO_TCP_ECN)
1269                                 gso.gso_type |= VIRTIO_NET_HDR_GSO_ECN;
1270                 } else
1271                         gso.gso_type = VIRTIO_NET_HDR_GSO_NONE;
1272 
1273                 if (skb->ip_summed == CHECKSUM_PARTIAL) {
1274                         gso.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
1275                         gso.csum_start = skb_checksum_start_offset(skb);
1276                         gso.csum_offset = skb->csum_offset;
1277                 } else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
1278                         gso.flags = VIRTIO_NET_HDR_F_DATA_VALID;
1279                 } /* else everything is zero */
1280 
1281                 if (unlikely(memcpy_toiovecend(iv, (void *)&gso, total,
1282                                                sizeof(gso))))
1283                         return -EFAULT;
1284                 total += tun->vnet_hdr_sz;
1285         }
1286 
1287         copied = total;
1288         total += skb->len;
1289         if (!vlan_tx_tag_present(skb)) {
1290                 len = min_t(int, skb->len, len);
1291         } else {
1292                 int copy, ret;
1293                 struct {
1294                         __be16 h_vlan_proto;
1295                         __be16 h_vlan_TCI;
1296                 } veth;
1297 
1298                 veth.h_vlan_proto = skb->vlan_proto;
1299                 veth.h_vlan_TCI = htons(vlan_tx_tag_get(skb));
1300 
1301                 vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
1302                 len = min_t(int, skb->len + VLAN_HLEN, len);
1303                 total += VLAN_HLEN;
1304 
1305                 copy = min_t(int, vlan_offset, len);
1306                 ret = skb_copy_datagram_const_iovec(skb, 0, iv, copied, copy);
1307                 len -= copy;
1308                 copied += copy;
1309                 if (ret || !len)
1310                         goto done;
1311 
1312                 copy = min_t(int, sizeof(veth), len);
1313                 ret = memcpy_toiovecend(iv, (void *)&veth, copied, copy);
1314                 len -= copy;
1315                 copied += copy;
1316                 if (ret || !len)
1317                         goto done;
1318         }
1319 
1320         skb_copy_datagram_const_iovec(skb, vlan_offset, iv, copied, len);
1321 
1322 done:
1323         tun->dev->stats.tx_packets++;
1324         tun->dev->stats.tx_bytes += len;
1325 
1326         return total;
1327 }
1328 
1329 static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
1330                            const struct iovec *iv, ssize_t len, int noblock)
1331 {
1332         struct sk_buff *skb;
1333         ssize_t ret = 0;
1334         int peeked, err, off = 0;
1335 
1336         tun_debug(KERN_INFO, tun, "tun_do_read\n");
1337 
1338         if (!len)
1339                 return ret;
1340 
1341         if (tun->dev->reg_state != NETREG_REGISTERED)
1342                 return -EIO;
1343 
1344         /* Read frames from queue */
1345         skb = __skb_recv_datagram(tfile->socket.sk, noblock ? MSG_DONTWAIT : 0,
1346                                   &peeked, &off, &err);
1347         if (skb) {
1348                 ret = tun_put_user(tun, tfile, skb, iv, len);
1349                 kfree_skb(skb);
1350         } else
1351                 ret = err;
1352 
1353         return ret;
1354 }
1355 
1356 static ssize_t tun_chr_aio_read(struct kiocb *iocb, const struct iovec *iv,
1357                             unsigned long count, loff_t pos)
1358 {
1359         struct file *file = iocb->ki_filp;
1360         struct tun_file *tfile = file->private_data;
1361         struct tun_struct *tun = __tun_get(tfile);
1362         ssize_t len, ret;
1363 
1364         if (!tun)
1365                 return -EBADFD;
1366         len = iov_length(iv, count);
1367         if (len < 0) {
1368                 ret = -EINVAL;
1369                 goto out;
1370         }
1371 
1372         ret = tun_do_read(tun, tfile, iv, len,
1373                           file->f_flags & O_NONBLOCK);
1374         ret = min_t(ssize_t, ret, len);
1375         if (ret > 0)
1376                 iocb->ki_pos = ret;
1377 out:
1378         tun_put(tun);
1379         return ret;
1380 }
1381 
1382 static void tun_free_netdev(struct net_device *dev)
1383 {
1384         struct tun_struct *tun = netdev_priv(dev);
1385 
1386         BUG_ON(!(list_empty(&tun->disabled)));
1387         tun_flow_uninit(tun);
1388         security_tun_dev_free_security(tun->security);
1389         free_netdev(dev);
1390 }
1391 
1392 static void tun_setup(struct net_device *dev)
1393 {
1394         struct tun_struct *tun = netdev_priv(dev);
1395 
1396         tun->owner = INVALID_UID;
1397         tun->group = INVALID_GID;
1398 
1399         dev->ethtool_ops = &tun_ethtool_ops;
1400         dev->destructor = tun_free_netdev;
1401 }
1402 
1403 /* Trivial set of netlink ops to allow deleting tun or tap
1404  * device with netlink.
1405  */
1406 static int tun_validate(struct nlattr *tb[], struct nlattr *data[])
1407 {
1408         return -EINVAL;
1409 }
1410 
1411 static struct rtnl_link_ops tun_link_ops __read_mostly = {
1412         .kind           = DRV_NAME,
1413         .priv_size      = sizeof(struct tun_struct),
1414         .setup          = tun_setup,
1415         .validate       = tun_validate,
1416 };
1417 
1418 static void tun_sock_write_space(struct sock *sk)
1419 {
1420         struct tun_file *tfile;
1421         wait_queue_head_t *wqueue;
1422 
1423         if (!sock_writeable(sk))
1424                 return;
1425 
1426         if (!test_and_clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags))
1427                 return;
1428 
1429         wqueue = sk_sleep(sk);
1430         if (wqueue && waitqueue_active(wqueue))
1431                 wake_up_interruptible_sync_poll(wqueue, POLLOUT |
1432                                                 POLLWRNORM | POLLWRBAND);
1433 
1434         tfile = container_of(sk, struct tun_file, sk);
1435         kill_fasync(&tfile->fasync, SIGIO, POLL_OUT);
1436 }
1437 
1438 static int tun_sendmsg(struct kiocb *iocb, struct socket *sock,
1439                        struct msghdr *m, size_t total_len)
1440 {
1441         int ret;
1442         struct tun_file *tfile = container_of(sock, struct tun_file, socket);
1443         struct tun_struct *tun = __tun_get(tfile);
1444 
1445         if (!tun)
1446                 return -EBADFD;
1447         ret = tun_get_user(tun, tfile, m->msg_control, m->msg_iov, total_len,
1448                            m->msg_iovlen, m->msg_flags & MSG_DONTWAIT);
1449         tun_put(tun);
1450         return ret;
1451 }
1452 
1453 static int tun_recvmsg(struct kiocb *iocb, struct socket *sock,
1454                        struct msghdr *m, size_t total_len,
1455                        int flags)
1456 {
1457         struct tun_file *tfile = container_of(sock, struct tun_file, socket);
1458         struct tun_struct *tun = __tun_get(tfile);
1459         int ret;
1460 
1461         if (!tun)
1462                 return -EBADFD;
1463 
1464         if (flags & ~(MSG_DONTWAIT|MSG_TRUNC|MSG_ERRQUEUE)) {
1465                 ret = -EINVAL;
1466                 goto out;
1467         }
1468         if (flags & MSG_ERRQUEUE) {
1469                 ret = sock_recv_errqueue(sock->sk, m, total_len,
1470                                          SOL_PACKET, TUN_TX_TIMESTAMP);
1471                 goto out;
1472         }
1473         ret = tun_do_read(tun, tfile, m->msg_iov, total_len,
1474                           flags & MSG_DONTWAIT);
1475         if (ret > total_len) {
1476                 m->msg_flags |= MSG_TRUNC;
1477                 ret = flags & MSG_TRUNC ? ret : total_len;
1478         }
1479 out:
1480         tun_put(tun);
1481         return ret;
1482 }
1483 
1484 static int tun_release(struct socket *sock)
1485 {
1486         if (sock->sk)
1487                 sock_put(sock->sk);
1488         return 0;
1489 }
1490 
1491 /* Ops structure to mimic raw sockets with tun */
1492 static const struct proto_ops tun_socket_ops = {
1493         .sendmsg = tun_sendmsg,
1494         .recvmsg = tun_recvmsg,
1495         .release = tun_release,
1496 };
1497 
1498 static struct proto tun_proto = {
1499         .name           = "tun",
1500         .owner          = THIS_MODULE,
1501         .obj_size       = sizeof(struct tun_file),
1502 };
1503 
1504 static int tun_flags(struct tun_struct *tun)
1505 {
1506         int flags = 0;
1507 
1508         if (tun->flags & TUN_TUN_DEV)
1509                 flags |= IFF_TUN;
1510         else
1511                 flags |= IFF_TAP;
1512 
1513         if (tun->flags & TUN_NO_PI)
1514                 flags |= IFF_NO_PI;
1515 
1516         /* This flag has no real effect.  We track the value for backwards
1517          * compatibility.
1518          */
1519         if (tun->flags & TUN_ONE_QUEUE)
1520                 flags |= IFF_ONE_QUEUE;
1521 
1522         if (tun->flags & TUN_VNET_HDR)
1523                 flags |= IFF_VNET_HDR;
1524 
1525         if (tun->flags & TUN_TAP_MQ)
1526                 flags |= IFF_MULTI_QUEUE;
1527 
1528         if (tun->flags & TUN_PERSIST)
1529                 flags |= IFF_PERSIST;
1530 
1531         return flags;
1532 }
1533 
1534 static ssize_t tun_show_flags(struct device *dev, struct device_attribute *attr,
1535                               char *buf)
1536 {
1537         struct tun_struct *tun = netdev_priv(to_net_dev(dev));
1538         return sprintf(buf, "0x%x\n", tun_flags(tun));
1539 }
1540 
1541 static ssize_t tun_show_owner(struct device *dev, struct device_attribute *attr,
1542                               char *buf)
1543 {
1544         struct tun_struct *tun = netdev_priv(to_net_dev(dev));
1545         return uid_valid(tun->owner)?
1546                 sprintf(buf, "%u\n",
1547                         from_kuid_munged(current_user_ns(), tun->owner)):
1548                 sprintf(buf, "-1\n");
1549 }
1550 
1551 static ssize_t tun_show_group(struct device *dev, struct device_attribute *attr,
1552                               char *buf)
1553 {
1554         struct tun_struct *tun = netdev_priv(to_net_dev(dev));
1555         return gid_valid(tun->group) ?
1556                 sprintf(buf, "%u\n",
1557                         from_kgid_munged(current_user_ns(), tun->group)):
1558                 sprintf(buf, "-1\n");
1559 }
1560 
1561 static DEVICE_ATTR(tun_flags, 0444, tun_show_flags, NULL);
1562 static DEVICE_ATTR(owner, 0444, tun_show_owner, NULL);
1563 static DEVICE_ATTR(group, 0444, tun_show_group, NULL);
1564 
1565 static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
1566 {
1567         struct tun_struct *tun;
1568         struct tun_file *tfile = file->private_data;
1569         struct net_device *dev;
1570         int err;
1571 
1572         if (tfile->detached)
1573                 return -EINVAL;
1574 
1575         dev = __dev_get_by_name(net, ifr->ifr_name);
1576         if (dev) {
1577                 if (ifr->ifr_flags & IFF_TUN_EXCL)
1578                         return -EBUSY;
1579                 if ((ifr->ifr_flags & IFF_TUN) && dev->netdev_ops == &tun_netdev_ops)
1580                         tun = netdev_priv(dev);
1581                 else if ((ifr->ifr_flags & IFF_TAP) && dev->netdev_ops == &tap_netdev_ops)
1582                         tun = netdev_priv(dev);
1583                 else
1584                         return -EINVAL;
1585 
1586                 if (!!(ifr->ifr_flags & IFF_MULTI_QUEUE) !=
1587                     !!(tun->flags & TUN_TAP_MQ))
1588                         return -EINVAL;
1589 
1590                 if (tun_not_capable(tun))
1591                         return -EPERM;
1592                 err = security_tun_dev_open(tun->security);
1593                 if (err < 0)
1594                         return err;
1595 
1596                 err = tun_attach(tun, file, ifr->ifr_flags & IFF_NOFILTER);
1597                 if (err < 0)
1598                         return err;
1599 
1600                 if (tun->flags & TUN_TAP_MQ &&
1601                     (tun->numqueues + tun->numdisabled > 1)) {
1602                         /* One or more queue has already been attached, no need
1603                          * to initialize the device again.
1604                          */
1605                         return 0;
1606                 }
1607         }
1608         else {
1609                 char *name;
1610                 unsigned long flags = 0;
1611                 int queues = ifr->ifr_flags & IFF_MULTI_QUEUE ?
1612                              MAX_TAP_QUEUES : 1;
1613 
1614                 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1615                         return -EPERM;
1616                 err = security_tun_dev_create();
1617                 if (err < 0)
1618                         return err;
1619 
1620                 /* Set dev type */
1621                 if (ifr->ifr_flags & IFF_TUN) {
1622                         /* TUN device */
1623                         flags |= TUN_TUN_DEV;
1624                         name = "tun%d";
1625                 } else if (ifr->ifr_flags & IFF_TAP) {
1626                         /* TAP device */
1627                         flags |= TUN_TAP_DEV;
1628                         name = "tap%d";
1629                 } else
1630                         return -EINVAL;
1631 
1632                 if (*ifr->ifr_name)
1633                         name = ifr->ifr_name;
1634 
1635                 dev = alloc_netdev_mqs(sizeof(struct tun_struct), name,
1636                                        tun_setup, queues, queues);
1637 
1638                 if (!dev)
1639                         return -ENOMEM;
1640 
1641                 dev_net_set(dev, net);
1642                 dev->rtnl_link_ops = &tun_link_ops;
1643                 dev->ifindex = tfile->ifindex;
1644 
1645                 tun = netdev_priv(dev);
1646                 tun->dev = dev;
1647                 tun->flags = flags;
1648                 tun->txflt.count = 0;
1649                 tun->vnet_hdr_sz = sizeof(struct virtio_net_hdr);
1650 
1651                 tun->filter_attached = false;
1652                 tun->sndbuf = tfile->socket.sk->sk_sndbuf;
1653 
1654                 spin_lock_init(&tun->lock);
1655 
1656                 err = security_tun_dev_alloc_security(&tun->security);
1657                 if (err < 0)
1658                         goto err_free_dev;
1659 
1660                 tun_net_init(dev);
1661                 tun_flow_init(tun);
1662 
1663                 dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST |
1664                                    TUN_USER_FEATURES | NETIF_F_HW_VLAN_CTAG_TX |
1665                                    NETIF_F_HW_VLAN_STAG_TX;
1666                 dev->features = dev->hw_features;
1667                 dev->vlan_features = dev->features &
1668                                      ~(NETIF_F_HW_VLAN_CTAG_TX |
1669                                        NETIF_F_HW_VLAN_STAG_TX);
1670 
1671                 INIT_LIST_HEAD(&tun->disabled);
1672                 err = tun_attach(tun, file, false);
1673                 if (err < 0)
1674                         goto err_free_flow;
1675 
1676                 err = register_netdevice(tun->dev);
1677                 if (err < 0)
1678                         goto err_detach;
1679 
1680                 if (device_create_file(&tun->dev->dev, &dev_attr_tun_flags) ||
1681                     device_create_file(&tun->dev->dev, &dev_attr_owner) ||
1682                     device_create_file(&tun->dev->dev, &dev_attr_group))
1683                         pr_err("Failed to create tun sysfs files\n");
1684         }
1685 
1686         netif_carrier_on(tun->dev);
1687 
1688         tun_debug(KERN_INFO, tun, "tun_set_iff\n");
1689 
1690         if (ifr->ifr_flags & IFF_NO_PI)
1691                 tun->flags |= TUN_NO_PI;
1692         else
1693                 tun->flags &= ~TUN_NO_PI;
1694 
1695         /* This flag has no real effect.  We track the value for backwards
1696          * compatibility.
1697          */
1698         if (ifr->ifr_flags & IFF_ONE_QUEUE)
1699                 tun->flags |= TUN_ONE_QUEUE;
1700         else
1701                 tun->flags &= ~TUN_ONE_QUEUE;
1702 
1703         if (ifr->ifr_flags & IFF_VNET_HDR)
1704                 tun->flags |= TUN_VNET_HDR;
1705         else
1706                 tun->flags &= ~TUN_VNET_HDR;
1707 
1708         if (ifr->ifr_flags & IFF_MULTI_QUEUE)
1709                 tun->flags |= TUN_TAP_MQ;
1710         else
1711                 tun->flags &= ~TUN_TAP_MQ;
1712 
1713         /* Make sure persistent devices do not get stuck in
1714          * xoff state.
1715          */
1716         if (netif_running(tun->dev))
1717                 netif_tx_wake_all_queues(tun->dev);
1718 
1719         strcpy(ifr->ifr_name, tun->dev->name);
1720         return 0;
1721 
1722 err_detach:
1723         tun_detach_all(dev);
1724 err_free_flow:
1725         tun_flow_uninit(tun);
1726         security_tun_dev_free_security(tun->security);
1727 err_free_dev:
1728         free_netdev(dev);
1729         return err;
1730 }
1731 
1732 static void tun_get_iff(struct net *net, struct tun_struct *tun,
1733                        struct ifreq *ifr)
1734 {
1735         tun_debug(KERN_INFO, tun, "tun_get_iff\n");
1736 
1737         strcpy(ifr->ifr_name, tun->dev->name);
1738 
1739         ifr->ifr_flags = tun_flags(tun);
1740 
1741 }
1742 
1743 /* This is like a cut-down ethtool ops, except done via tun fd so no
1744  * privs required. */
1745 static int set_offload(struct tun_struct *tun, unsigned long arg)
1746 {
1747         netdev_features_t features = 0;
1748 
1749         if (arg & TUN_F_CSUM) {
1750                 features |= NETIF_F_HW_CSUM;
1751                 arg &= ~TUN_F_CSUM;
1752 
1753                 if (arg & (TUN_F_TSO4|TUN_F_TSO6)) {
1754                         if (arg & TUN_F_TSO_ECN) {
1755                                 features |= NETIF_F_TSO_ECN;
1756                                 arg &= ~TUN_F_TSO_ECN;
1757                         }
1758                         if (arg & TUN_F_TSO4)
1759                                 features |= NETIF_F_TSO;
1760                         if (arg & TUN_F_TSO6)
1761                                 features |= NETIF_F_TSO6;
1762                         arg &= ~(TUN_F_TSO4|TUN_F_TSO6);
1763                 }
1764 
1765                 if (arg & TUN_F_UFO) {
1766                         features |= NETIF_F_UFO;
1767                         arg &= ~TUN_F_UFO;
1768                 }
1769         }
1770 
1771         /* This gives the user a way to test for new features in future by
1772          * trying to set them. */
1773         if (arg)
1774                 return -EINVAL;
1775 
1776         tun->set_features = features;
1777         netdev_update_features(tun->dev);
1778 
1779         return 0;
1780 }
1781 
1782 static void tun_detach_filter(struct tun_struct *tun, int n)
1783 {
1784         int i;
1785         struct tun_file *tfile;
1786 
1787         for (i = 0; i < n; i++) {
1788                 tfile = rtnl_dereference(tun->tfiles[i]);
1789                 sk_detach_filter(tfile->socket.sk);
1790         }
1791 
1792         tun->filter_attached = false;
1793 }
1794 
1795 static int tun_attach_filter(struct tun_struct *tun)
1796 {
1797         int i, ret = 0;
1798         struct tun_file *tfile;
1799 
1800         for (i = 0; i < tun->numqueues; i++) {
1801                 tfile = rtnl_dereference(tun->tfiles[i]);
1802                 ret = sk_attach_filter(&tun->fprog, tfile->socket.sk);
1803                 if (ret) {
1804                         tun_detach_filter(tun, i);
1805                         return ret;
1806                 }
1807         }
1808 
1809         tun->filter_attached = true;
1810         return ret;
1811 }
1812 
1813 static void tun_set_sndbuf(struct tun_struct *tun)
1814 {
1815         struct tun_file *tfile;
1816         int i;
1817 
1818         for (i = 0; i < tun->numqueues; i++) {
1819                 tfile = rtnl_dereference(tun->tfiles[i]);
1820                 tfile->socket.sk->sk_sndbuf = tun->sndbuf;
1821         }
1822 }
1823 
1824 static int tun_set_queue(struct file *file, struct ifreq *ifr)
1825 {
1826         struct tun_file *tfile = file->private_data;
1827         struct tun_struct *tun;
1828         int ret = 0;
1829 
1830         rtnl_lock();
1831 
1832         if (ifr->ifr_flags & IFF_ATTACH_QUEUE) {
1833                 tun = tfile->detached;
1834                 if (!tun) {
1835                         ret = -EINVAL;
1836                         goto unlock;
1837                 }
1838                 ret = security_tun_dev_attach_queue(tun->security);
1839                 if (ret < 0)
1840                         goto unlock;
1841                 ret = tun_attach(tun, file, false);
1842         } else if (ifr->ifr_flags & IFF_DETACH_QUEUE) {
1843                 tun = rtnl_dereference(tfile->tun);
1844                 if (!tun || !(tun->flags & TUN_TAP_MQ) || tfile->detached)
1845                         ret = -EINVAL;
1846                 else
1847                         __tun_detach(tfile, false);
1848         } else
1849                 ret = -EINVAL;
1850 
1851 unlock:
1852         rtnl_unlock();
1853         return ret;
1854 }
1855 
1856 static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
1857                             unsigned long arg, int ifreq_len)
1858 {
1859         struct tun_file *tfile = file->private_data;
1860         struct tun_struct *tun;
1861         void __user* argp = (void __user*)arg;
1862         struct ifreq ifr;
1863         kuid_t owner;
1864         kgid_t group;
1865         int sndbuf;
1866         int vnet_hdr_sz;
1867         unsigned int ifindex;
1868         int ret;
1869 
1870         if (cmd == TUNSETIFF || cmd == TUNSETQUEUE || _IOC_TYPE(cmd) == 0x89) {
1871                 if (copy_from_user(&ifr, argp, ifreq_len))
1872                         return -EFAULT;
1873         } else {
1874                 memset(&ifr, 0, sizeof(ifr));
1875         }
1876         if (cmd == TUNGETFEATURES) {
1877                 /* Currently this just means: "what IFF flags are valid?".
1878                  * This is needed because we never checked for invalid flags on
1879                  * TUNSETIFF. */
1880                 return put_user(IFF_TUN | IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE |
1881                                 IFF_VNET_HDR | IFF_MULTI_QUEUE,
1882                                 (unsigned int __user*)argp);
1883         } else if (cmd == TUNSETQUEUE)
1884                 return tun_set_queue(file, &ifr);
1885 
1886         ret = 0;
1887         rtnl_lock();
1888 
1889         tun = __tun_get(tfile);
1890         if (cmd == TUNSETIFF && !tun) {
1891                 ifr.ifr_name[IFNAMSIZ-1] = '\0';
1892 
1893                 ret = tun_set_iff(tfile->net, file, &ifr);
1894 
1895                 if (ret)
1896                         goto unlock;
1897 
1898                 if (copy_to_user(argp, &ifr, ifreq_len))
1899                         ret = -EFAULT;
1900                 goto unlock;
1901         }
1902         if (cmd == TUNSETIFINDEX) {
1903                 ret = -EPERM;
1904                 if (tun)
1905                         goto unlock;
1906 
1907                 ret = -EFAULT;
1908                 if (copy_from_user(&ifindex, argp, sizeof(ifindex)))
1909                         goto unlock;
1910 
1911                 ret = 0;
1912                 tfile->ifindex = ifindex;
1913                 goto unlock;
1914         }
1915 
1916         ret = -EBADFD;
1917         if (!tun)
1918                 goto unlock;
1919 
1920         tun_debug(KERN_INFO, tun, "tun_chr_ioctl cmd %u\n", cmd);
1921 
1922         ret = 0;
1923         switch (cmd) {
1924         case TUNGETIFF:
1925                 tun_get_iff(current->nsproxy->net_ns, tun, &ifr);
1926 
1927                 if (tfile->detached)
1928                         ifr.ifr_flags |= IFF_DETACH_QUEUE;
1929                 if (!tfile->socket.sk->sk_filter)
1930                         ifr.ifr_flags |= IFF_NOFILTER;
1931 
1932                 if (copy_to_user(argp, &ifr, ifreq_len))
1933                         ret = -EFAULT;
1934                 break;
1935 
1936         case TUNSETNOCSUM:
1937                 /* Disable/Enable checksum */
1938 
1939                 /* [unimplemented] */
1940                 tun_debug(KERN_INFO, tun, "ignored: set checksum %s\n",
1941                           arg ? "disabled" : "enabled");
1942                 break;
1943 
1944         case TUNSETPERSIST:
1945                 /* Disable/Enable persist mode. Keep an extra reference to the
1946                  * module to prevent the module being unprobed.
1947                  */
1948                 if (arg && !(tun->flags & TUN_PERSIST)) {
1949                         tun->flags |= TUN_PERSIST;
1950                         __module_get(THIS_MODULE);
1951                 }
1952                 if (!arg && (tun->flags & TUN_PERSIST)) {
1953                         tun->flags &= ~TUN_PERSIST;
1954                         module_put(THIS_MODULE);
1955                 }
1956 
1957                 tun_debug(KERN_INFO, tun, "persist %s\n",
1958                           arg ? "enabled" : "disabled");
1959                 break;
1960 
1961         case TUNSETOWNER:
1962                 /* Set owner of the device */
1963                 owner = make_kuid(current_user_ns(), arg);
1964                 if (!uid_valid(owner)) {
1965                         ret = -EINVAL;
1966                         break;
1967                 }
1968                 tun->owner = owner;
1969                 tun_debug(KERN_INFO, tun, "owner set to %u\n",
1970                           from_kuid(&init_user_ns, tun->owner));
1971                 break;
1972 
1973         case TUNSETGROUP:
1974                 /* Set group of the device */
1975                 group = make_kgid(current_user_ns(), arg);
1976                 if (!gid_valid(group)) {
1977                         ret = -EINVAL;
1978                         break;
1979                 }
1980                 tun->group = group;
1981                 tun_debug(KERN_INFO, tun, "group set to %u\n",
1982                           from_kgid(&init_user_ns, tun->group));
1983                 break;
1984 
1985         case TUNSETLINK:
1986                 /* Only allow setting the type when the interface is down */
1987                 if (tun->dev->flags & IFF_UP) {
1988                         tun_debug(KERN_INFO, tun,
1989                                   "Linktype set failed because interface is up\n");
1990                         ret = -EBUSY;
1991                 } else {
1992                         tun->dev->type = (int) arg;
1993                         tun_debug(KERN_INFO, tun, "linktype set to %d\n",
1994                                   tun->dev->type);
1995                         ret = 0;
1996                 }
1997                 break;
1998 
1999 #ifdef TUN_DEBUG
2000         case TUNSETDEBUG:
2001                 tun->debug = arg;
2002                 break;
2003 #endif
2004         case TUNSETOFFLOAD:
2005                 ret = set_offload(tun, arg);
2006                 break;
2007 
2008         case TUNSETTXFILTER:
2009                 /* Can be set only for TAPs */
2010                 ret = -EINVAL;
2011                 if ((tun->flags & TUN_TYPE_MASK) != TUN_TAP_DEV)
2012                         break;
2013                 ret = update_filter(&tun->txflt, (void __user *)arg);
2014                 break;
2015 
2016         case SIOCGIFHWADDR:
2017                 /* Get hw address */
2018                 memcpy(ifr.ifr_hwaddr.sa_data, tun->dev->dev_addr, ETH_ALEN);
2019                 ifr.ifr_hwaddr.sa_family = tun->dev->type;
2020                 if (copy_to_user(argp, &ifr, ifreq_len))
2021                         ret = -EFAULT;
2022                 break;
2023 
2024         case SIOCSIFHWADDR:
2025                 /* Set hw address */
2026                 tun_debug(KERN_DEBUG, tun, "set hw address: %pM\n",
2027                           ifr.ifr_hwaddr.sa_data);
2028 
2029                 ret = dev_set_mac_address(tun->dev, &ifr.ifr_hwaddr);
2030                 break;
2031 
2032         case TUNGETSNDBUF:
2033                 sndbuf = tfile->socket.sk->sk_sndbuf;
2034                 if (copy_to_user(argp, &sndbuf, sizeof(sndbuf)))
2035                         ret = -EFAULT;
2036                 break;
2037 
2038         case TUNSETSNDBUF:
2039                 if (copy_from_user(&sndbuf, argp, sizeof(sndbuf))) {
2040                         ret = -EFAULT;
2041                         break;
2042                 }
2043 
2044                 tun->sndbuf = sndbuf;
2045                 tun_set_sndbuf(tun);
2046                 break;
2047 
2048         case TUNGETVNETHDRSZ:
2049                 vnet_hdr_sz = tun->vnet_hdr_sz;
2050                 if (copy_to_user(argp, &vnet_hdr_sz, sizeof(vnet_hdr_sz)))
2051                         ret = -EFAULT;
2052                 break;
2053 
2054         case TUNSETVNETHDRSZ:
2055                 if (copy_from_user(&vnet_hdr_sz, argp, sizeof(vnet_hdr_sz))) {
2056                         ret = -EFAULT;
2057                         break;
2058                 }
2059                 if (vnet_hdr_sz < (int)sizeof(struct virtio_net_hdr)) {
2060                         ret = -EINVAL;
2061                         break;
2062                 }
2063 
2064                 tun->vnet_hdr_sz = vnet_hdr_sz;
2065                 break;
2066 
2067         case TUNATTACHFILTER:
2068                 /* Can be set only for TAPs */
2069                 ret = -EINVAL;
2070                 if ((tun->flags & TUN_TYPE_MASK) != TUN_TAP_DEV)
2071                         break;
2072                 ret = -EFAULT;
2073                 if (copy_from_user(&tun->fprog, argp, sizeof(tun->fprog)))
2074                         break;
2075 
2076                 ret = tun_attach_filter(tun);
2077                 break;
2078 
2079         case TUNDETACHFILTER:
2080                 /* Can be set only for TAPs */
2081                 ret = -EINVAL;
2082                 if ((tun->flags & TUN_TYPE_MASK) != TUN_TAP_DEV)
2083                         break;
2084                 ret = 0;
2085                 tun_detach_filter(tun, tun->numqueues);
2086                 break;
2087 
2088         case TUNGETFILTER:
2089                 ret = -EINVAL;
2090                 if ((tun->flags & TUN_TYPE_MASK) != TUN_TAP_DEV)
2091                         break;
2092                 ret = -EFAULT;
2093                 if (copy_to_user(argp, &tun->fprog, sizeof(tun->fprog)))
2094                         break;
2095                 ret = 0;
2096                 break;
2097 
2098         default:
2099                 ret = -EINVAL;
2100                 break;
2101         }
2102 
2103 unlock:
2104         rtnl_unlock();
2105         if (tun)
2106                 tun_put(tun);
2107         return ret;
2108 }
2109 
2110 static long tun_chr_ioctl(struct file *file,
2111                           unsigned int cmd, unsigned long arg)
2112 {
2113         return __tun_chr_ioctl(file, cmd, arg, sizeof (struct ifreq));
2114 }
2115 
2116 #ifdef CONFIG_COMPAT
2117 static long tun_chr_compat_ioctl(struct file *file,
2118                          unsigned int cmd, unsigned long arg)
2119 {
2120         switch (cmd) {
2121         case TUNSETIFF:
2122         case TUNGETIFF:
2123         case TUNSETTXFILTER:
2124         case TUNGETSNDBUF:
2125         case TUNSETSNDBUF:
2126         case SIOCGIFHWADDR:
2127         case SIOCSIFHWADDR:
2128                 arg = (unsigned long)compat_ptr(arg);
2129                 break;
2130         default:
2131                 arg = (compat_ulong_t)arg;
2132                 break;
2133         }
2134 
2135         /*
2136          * compat_ifreq is shorter than ifreq, so we must not access beyond
2137          * the end of that structure. All fields that are used in this
2138          * driver are compatible though, we don't need to convert the
2139          * contents.
2140          */
2141         return __tun_chr_ioctl(file, cmd, arg, sizeof(struct compat_ifreq));
2142 }
2143 #endif /* CONFIG_COMPAT */
2144 
2145 static int tun_chr_fasync(int fd, struct file *file, int on)
2146 {
2147         struct tun_file *tfile = file->private_data;
2148         int ret;
2149 
2150         if ((ret = fasync_helper(fd, file, on, &tfile->fasync)) < 0)
2151                 goto out;
2152 
2153         if (on) {
2154                 ret = __f_setown(file, task_pid(current), PIDTYPE_PID, 0);
2155                 if (ret)
2156                         goto out;
2157                 tfile->flags |= TUN_FASYNC;
2158         } else
2159                 tfile->flags &= ~TUN_FASYNC;
2160         ret = 0;
2161 out:
2162         return ret;
2163 }
2164 
2165 static int tun_chr_open(struct inode *inode, struct file * file)
2166 {
2167         struct tun_file *tfile;
2168 
2169         DBG1(KERN_INFO, "tunX: tun_chr_open\n");
2170 
2171         tfile = (struct tun_file *)sk_alloc(&init_net, AF_UNSPEC, GFP_KERNEL,
2172                                             &tun_proto);
2173         if (!tfile)
2174                 return -ENOMEM;
2175         RCU_INIT_POINTER(tfile->tun, NULL);
2176         tfile->net = get_net(current->nsproxy->net_ns);
2177         tfile->flags = 0;
2178         tfile->ifindex = 0;
2179 
2180         init_waitqueue_head(&tfile->wq.wait);
2181         RCU_INIT_POINTER(tfile->socket.wq, &tfile->wq);
2182 
2183         tfile->socket.file = file;
2184         tfile->socket.ops = &tun_socket_ops;
2185 
2186         sock_init_data(&tfile->socket, &tfile->sk);
2187         sk_change_net(&tfile->sk, tfile->net);
2188 
2189         tfile->sk.sk_write_space = tun_sock_write_space;
2190         tfile->sk.sk_sndbuf = INT_MAX;
2191 
2192         file->private_data = tfile;
2193         set_bit(SOCK_EXTERNALLY_ALLOCATED, &tfile->socket.flags);
2194         INIT_LIST_HEAD(&tfile->next);
2195 
2196         sock_set_flag(&tfile->sk, SOCK_ZEROCOPY);
2197 
2198         return 0;
2199 }
2200 
2201 static int tun_chr_close(struct inode *inode, struct file *file)
2202 {
2203         struct tun_file *tfile = file->private_data;
2204         struct net *net = tfile->net;
2205 
2206         tun_detach(tfile, true);
2207         put_net(net);
2208 
2209         return 0;
2210 }
2211 
2212 #ifdef CONFIG_PROC_FS
2213 static int tun_chr_show_fdinfo(struct seq_file *m, struct file *f)
2214 {
2215         struct tun_struct *tun;
2216         struct ifreq ifr;
2217 
2218         memset(&ifr, 0, sizeof(ifr));
2219 
2220         rtnl_lock();
2221         tun = tun_get(f);
2222         if (tun)
2223                 tun_get_iff(current->nsproxy->net_ns, tun, &ifr);
2224         rtnl_unlock();
2225 
2226         if (tun)
2227                 tun_put(tun);
2228 
2229         return seq_printf(m, "iff:\t%s\n", ifr.ifr_name);
2230 }
2231 #endif
2232 
2233 static const struct file_operations tun_fops = {
2234         .owner  = THIS_MODULE,
2235         .llseek = no_llseek,
2236         .read  = do_sync_read,
2237         .aio_read  = tun_chr_aio_read,
2238         .write = do_sync_write,
2239         .aio_write = tun_chr_aio_write,
2240         .poll   = tun_chr_poll,
2241         .unlocked_ioctl = tun_chr_ioctl,
2242 #ifdef CONFIG_COMPAT
2243         .compat_ioctl = tun_chr_compat_ioctl,
2244 #endif
2245         .open   = tun_chr_open,
2246         .release = tun_chr_close,
2247         .fasync = tun_chr_fasync,
2248 #ifdef CONFIG_PROC_FS
2249         .show_fdinfo = tun_chr_show_fdinfo,
2250 #endif
2251 };
2252 
2253 static struct miscdevice tun_miscdev = {
2254         .minor = TUN_MINOR,
2255         .name = "tun",
2256         .nodename = "net/tun",
2257         .fops = &tun_fops,
2258 };
2259 
2260 /* ethtool interface */
2261 
2262 static int tun_get_settings(struct net_device *dev, struct ethtool_cmd *cmd)
2263 {
2264         cmd->supported          = 0;
2265         cmd->advertising        = 0;
2266         ethtool_cmd_speed_set(cmd, SPEED_10);
2267         cmd->duplex             = DUPLEX_FULL;
2268         cmd->port               = PORT_TP;
2269         cmd->phy_address        = 0;
2270         cmd->transceiver        = XCVR_INTERNAL;
2271         cmd->autoneg            = AUTONEG_DISABLE;
2272         cmd->maxtxpkt           = 0;
2273         cmd->maxrxpkt           = 0;
2274         return 0;
2275 }
2276 
2277 static void tun_get_drvinfo(struct net_device *dev, struct ethtool_drvinfo *info)
2278 {
2279         struct tun_struct *tun = netdev_priv(dev);
2280 
2281         strlcpy(info->driver, DRV_NAME, sizeof(info->driver));
2282         strlcpy(info->version, DRV_VERSION, sizeof(info->version));
2283 
2284         switch (tun->flags & TUN_TYPE_MASK) {
2285         case TUN_TUN_DEV:
2286                 strlcpy(info->bus_info, "tun", sizeof(info->bus_info));
2287                 break;
2288         case TUN_TAP_DEV:
2289                 strlcpy(info->bus_info, "tap", sizeof(info->bus_info));
2290                 break;
2291         }
2292 }
2293 
2294 static u32 tun_get_msglevel(struct net_device *dev)
2295 {
2296 #ifdef TUN_DEBUG
2297         struct tun_struct *tun = netdev_priv(dev);
2298         return tun->debug;
2299 #else
2300         return -EOPNOTSUPP;
2301 #endif
2302 }
2303 
2304 static void tun_set_msglevel(struct net_device *dev, u32 value)
2305 {
2306 #ifdef TUN_DEBUG
2307         struct tun_struct *tun = netdev_priv(dev);
2308         tun->debug = value;
2309 #endif
2310 }
2311 
2312 static const struct ethtool_ops tun_ethtool_ops = {
2313         .get_settings   = tun_get_settings,
2314         .get_drvinfo    = tun_get_drvinfo,
2315         .get_msglevel   = tun_get_msglevel,
2316         .set_msglevel   = tun_set_msglevel,
2317         .get_link       = ethtool_op_get_link,
2318         .get_ts_info    = ethtool_op_get_ts_info,
2319 };
2320 
2321 
2322 static int __init tun_init(void)
2323 {
2324         int ret = 0;
2325 
2326         pr_info("%s, %s\n", DRV_DESCRIPTION, DRV_VERSION);
2327         pr_info("%s\n", DRV_COPYRIGHT);
2328 
2329         ret = rtnl_link_register(&tun_link_ops);
2330         if (ret) {
2331                 pr_err("Can't register link_ops\n");
2332                 goto err_linkops;
2333         }
2334 
2335         ret = misc_register(&tun_miscdev);
2336         if (ret) {
2337                 pr_err("Can't register misc device %d\n", TUN_MINOR);
2338                 goto err_misc;
2339         }
2340         return  0;
2341 err_misc:
2342         rtnl_link_unregister(&tun_link_ops);
2343 err_linkops:
2344         return ret;
2345 }
2346 
2347 static void tun_cleanup(void)
2348 {
2349         misc_deregister(&tun_miscdev);
2350         rtnl_link_unregister(&tun_link_ops);
2351 }
2352 
2353 /* Get an underlying socket object from tun file.  Returns error unless file is
2354  * attached to a device.  The returned object works like a packet socket, it
2355  * can be used for sock_sendmsg/sock_recvmsg.  The caller is responsible for
2356  * holding a reference to the file for as long as the socket is in use. */
2357 struct socket *tun_get_socket(struct file *file)
2358 {
2359         struct tun_file *tfile;
2360         if (file->f_op != &tun_fops)
2361                 return ERR_PTR(-EINVAL);
2362         tfile = file->private_data;
2363         if (!tfile)
2364                 return ERR_PTR(-EBADFD);
2365         return &tfile->socket;
2366 }
2367 EXPORT_SYMBOL_GPL(tun_get_socket);
2368 
2369 module_init(tun_init);
2370 module_exit(tun_cleanup);
2371 MODULE_DESCRIPTION(DRV_DESCRIPTION);
2372 MODULE_AUTHOR(DRV_COPYRIGHT);
2373 MODULE_LICENSE("GPL");
2374 MODULE_ALIAS_MISCDEV(TUN_MINOR);
2375 MODULE_ALIAS("devname:net/tun");
2376 

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