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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 #include <linux/uio.h>
 74 #include <linux/skb_array.h>
 75 
 76 #include <linux/uaccess.h>
 77 
 78 /* Uncomment to enable debugging */
 79 /* #define TUN_DEBUG 1 */
 80 
 81 #ifdef TUN_DEBUG
 82 static int debug;
 83 
 84 #define tun_debug(level, tun, fmt, args...)                     \
 85 do {                                                            \
 86         if (tun->debug)                                         \
 87                 netdev_printk(level, tun->dev, fmt, ##args);    \
 88 } while (0)
 89 #define DBG1(level, fmt, args...)                               \
 90 do {                                                            \
 91         if (debug == 2)                                         \
 92                 printk(level fmt, ##args);                      \
 93 } while (0)
 94 #else
 95 #define tun_debug(level, tun, fmt, args...)                     \
 96 do {                                                            \
 97         if (0)                                                  \
 98                 netdev_printk(level, tun->dev, fmt, ##args);    \
 99 } while (0)
100 #define DBG1(level, fmt, args...)                               \
101 do {                                                            \
102         if (0)                                                  \
103                 printk(level fmt, ##args);                      \
104 } while (0)
105 #endif
106 
107 /* TUN device flags */
108 
109 /* IFF_ATTACH_QUEUE is never stored in device flags,
110  * overload it to mean fasync when stored there.
111  */
112 #define TUN_FASYNC      IFF_ATTACH_QUEUE
113 /* High bits in flags field are unused. */
114 #define TUN_VNET_LE     0x80000000
115 #define TUN_VNET_BE     0x40000000
116 
117 #define TUN_FEATURES (IFF_NO_PI | IFF_ONE_QUEUE | IFF_VNET_HDR | \
118                       IFF_MULTI_QUEUE)
119 #define GOODCOPY_LEN 128
120 
121 #define FLT_EXACT_COUNT 8
122 struct tap_filter {
123         unsigned int    count;    /* Number of addrs. Zero means disabled */
124         u32             mask[2];  /* Mask of the hashed addrs */
125         unsigned char   addr[FLT_EXACT_COUNT][ETH_ALEN];
126 };
127 
128 /* MAX_TAP_QUEUES 256 is chosen to allow rx/tx queues to be equal
129  * to max number of VCPUs in guest. */
130 #define MAX_TAP_QUEUES 256
131 #define MAX_TAP_FLOWS  4096
132 
133 #define TUN_FLOW_EXPIRE (3 * HZ)
134 
135 struct tun_pcpu_stats {
136         u64 rx_packets;
137         u64 rx_bytes;
138         u64 tx_packets;
139         u64 tx_bytes;
140         struct u64_stats_sync syncp;
141         u32 rx_dropped;
142         u32 tx_dropped;
143         u32 rx_frame_errors;
144 };
145 
146 /* A tun_file connects an open character device to a tuntap netdevice. It
147  * also contains all socket related structures (except sock_fprog and tap_filter)
148  * to serve as one transmit queue for tuntap device. The sock_fprog and
149  * tap_filter were kept in tun_struct since they were used for filtering for the
150  * netdevice not for a specific queue (at least I didn't see the requirement for
151  * this).
152  *
153  * RCU usage:
154  * The tun_file and tun_struct are loosely coupled, the pointer from one to the
155  * other can only be read while rcu_read_lock or rtnl_lock is held.
156  */
157 struct tun_file {
158         struct sock sk;
159         struct socket socket;
160         struct socket_wq wq;
161         struct tun_struct __rcu *tun;
162         struct fasync_struct *fasync;
163         /* only used for fasnyc */
164         unsigned int flags;
165         union {
166                 u16 queue_index;
167                 unsigned int ifindex;
168         };
169         struct list_head next;
170         struct tun_struct *detached;
171         struct skb_array tx_array;
172 };
173 
174 struct tun_flow_entry {
175         struct hlist_node hash_link;
176         struct rcu_head rcu;
177         struct tun_struct *tun;
178 
179         u32 rxhash;
180         u32 rps_rxhash;
181         int queue_index;
182         unsigned long updated;
183 };
184 
185 #define TUN_NUM_FLOW_ENTRIES 1024
186 
187 /* Since the socket were moved to tun_file, to preserve the behavior of persist
188  * device, socket filter, sndbuf and vnet header size were restore when the
189  * file were attached to a persist device.
190  */
191 struct tun_struct {
192         struct tun_file __rcu   *tfiles[MAX_TAP_QUEUES];
193         unsigned int            numqueues;
194         unsigned int            flags;
195         kuid_t                  owner;
196         kgid_t                  group;
197 
198         struct net_device       *dev;
199         netdev_features_t       set_features;
200 #define TUN_USER_FEATURES (NETIF_F_HW_CSUM|NETIF_F_TSO_ECN|NETIF_F_TSO| \
201                           NETIF_F_TSO6|NETIF_F_UFO)
202 
203         int                     align;
204         int                     vnet_hdr_sz;
205         int                     sndbuf;
206         struct tap_filter       txflt;
207         struct sock_fprog       fprog;
208         /* protected by rtnl lock */
209         bool                    filter_attached;
210 #ifdef TUN_DEBUG
211         int debug;
212 #endif
213         spinlock_t lock;
214         struct hlist_head flows[TUN_NUM_FLOW_ENTRIES];
215         struct timer_list flow_gc_timer;
216         unsigned long ageing_time;
217         unsigned int numdisabled;
218         struct list_head disabled;
219         void *security;
220         u32 flow_count;
221         struct tun_pcpu_stats __percpu *pcpu_stats;
222 };
223 
224 #ifdef CONFIG_TUN_VNET_CROSS_LE
225 static inline bool tun_legacy_is_little_endian(struct tun_struct *tun)
226 {
227         return tun->flags & TUN_VNET_BE ? false :
228                 virtio_legacy_is_little_endian();
229 }
230 
231 static long tun_get_vnet_be(struct tun_struct *tun, int __user *argp)
232 {
233         int be = !!(tun->flags & TUN_VNET_BE);
234 
235         if (put_user(be, argp))
236                 return -EFAULT;
237 
238         return 0;
239 }
240 
241 static long tun_set_vnet_be(struct tun_struct *tun, int __user *argp)
242 {
243         int be;
244 
245         if (get_user(be, argp))
246                 return -EFAULT;
247 
248         if (be)
249                 tun->flags |= TUN_VNET_BE;
250         else
251                 tun->flags &= ~TUN_VNET_BE;
252 
253         return 0;
254 }
255 #else
256 static inline bool tun_legacy_is_little_endian(struct tun_struct *tun)
257 {
258         return virtio_legacy_is_little_endian();
259 }
260 
261 static long tun_get_vnet_be(struct tun_struct *tun, int __user *argp)
262 {
263         return -EINVAL;
264 }
265 
266 static long tun_set_vnet_be(struct tun_struct *tun, int __user *argp)
267 {
268         return -EINVAL;
269 }
270 #endif /* CONFIG_TUN_VNET_CROSS_LE */
271 
272 static inline bool tun_is_little_endian(struct tun_struct *tun)
273 {
274         return tun->flags & TUN_VNET_LE ||
275                 tun_legacy_is_little_endian(tun);
276 }
277 
278 static inline u16 tun16_to_cpu(struct tun_struct *tun, __virtio16 val)
279 {
280         return __virtio16_to_cpu(tun_is_little_endian(tun), val);
281 }
282 
283 static inline __virtio16 cpu_to_tun16(struct tun_struct *tun, u16 val)
284 {
285         return __cpu_to_virtio16(tun_is_little_endian(tun), val);
286 }
287 
288 static inline u32 tun_hashfn(u32 rxhash)
289 {
290         return rxhash & 0x3ff;
291 }
292 
293 static struct tun_flow_entry *tun_flow_find(struct hlist_head *head, u32 rxhash)
294 {
295         struct tun_flow_entry *e;
296 
297         hlist_for_each_entry_rcu(e, head, hash_link) {
298                 if (e->rxhash == rxhash)
299                         return e;
300         }
301         return NULL;
302 }
303 
304 static struct tun_flow_entry *tun_flow_create(struct tun_struct *tun,
305                                               struct hlist_head *head,
306                                               u32 rxhash, u16 queue_index)
307 {
308         struct tun_flow_entry *e = kmalloc(sizeof(*e), GFP_ATOMIC);
309 
310         if (e) {
311                 tun_debug(KERN_INFO, tun, "create flow: hash %u index %u\n",
312                           rxhash, queue_index);
313                 e->updated = jiffies;
314                 e->rxhash = rxhash;
315                 e->rps_rxhash = 0;
316                 e->queue_index = queue_index;
317                 e->tun = tun;
318                 hlist_add_head_rcu(&e->hash_link, head);
319                 ++tun->flow_count;
320         }
321         return e;
322 }
323 
324 static void tun_flow_delete(struct tun_struct *tun, struct tun_flow_entry *e)
325 {
326         tun_debug(KERN_INFO, tun, "delete flow: hash %u index %u\n",
327                   e->rxhash, e->queue_index);
328         hlist_del_rcu(&e->hash_link);
329         kfree_rcu(e, rcu);
330         --tun->flow_count;
331 }
332 
333 static void tun_flow_flush(struct tun_struct *tun)
334 {
335         int i;
336 
337         spin_lock_bh(&tun->lock);
338         for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) {
339                 struct tun_flow_entry *e;
340                 struct hlist_node *n;
341 
342                 hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link)
343                         tun_flow_delete(tun, e);
344         }
345         spin_unlock_bh(&tun->lock);
346 }
347 
348 static void tun_flow_delete_by_queue(struct tun_struct *tun, u16 queue_index)
349 {
350         int i;
351 
352         spin_lock_bh(&tun->lock);
353         for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) {
354                 struct tun_flow_entry *e;
355                 struct hlist_node *n;
356 
357                 hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link) {
358                         if (e->queue_index == queue_index)
359                                 tun_flow_delete(tun, e);
360                 }
361         }
362         spin_unlock_bh(&tun->lock);
363 }
364 
365 static void tun_flow_cleanup(unsigned long data)
366 {
367         struct tun_struct *tun = (struct tun_struct *)data;
368         unsigned long delay = tun->ageing_time;
369         unsigned long next_timer = jiffies + delay;
370         unsigned long count = 0;
371         int i;
372 
373         tun_debug(KERN_INFO, tun, "tun_flow_cleanup\n");
374 
375         spin_lock_bh(&tun->lock);
376         for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) {
377                 struct tun_flow_entry *e;
378                 struct hlist_node *n;
379 
380                 hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link) {
381                         unsigned long this_timer;
382                         count++;
383                         this_timer = e->updated + delay;
384                         if (time_before_eq(this_timer, jiffies))
385                                 tun_flow_delete(tun, e);
386                         else if (time_before(this_timer, next_timer))
387                                 next_timer = this_timer;
388                 }
389         }
390 
391         if (count)
392                 mod_timer(&tun->flow_gc_timer, round_jiffies_up(next_timer));
393         spin_unlock_bh(&tun->lock);
394 }
395 
396 static void tun_flow_update(struct tun_struct *tun, u32 rxhash,
397                             struct tun_file *tfile)
398 {
399         struct hlist_head *head;
400         struct tun_flow_entry *e;
401         unsigned long delay = tun->ageing_time;
402         u16 queue_index = tfile->queue_index;
403 
404         if (!rxhash)
405                 return;
406         else
407                 head = &tun->flows[tun_hashfn(rxhash)];
408 
409         rcu_read_lock();
410 
411         /* We may get a very small possibility of OOO during switching, not
412          * worth to optimize.*/
413         if (tun->numqueues == 1 || tfile->detached)
414                 goto unlock;
415 
416         e = tun_flow_find(head, rxhash);
417         if (likely(e)) {
418                 /* TODO: keep queueing to old queue until it's empty? */
419                 e->queue_index = queue_index;
420                 e->updated = jiffies;
421                 sock_rps_record_flow_hash(e->rps_rxhash);
422         } else {
423                 spin_lock_bh(&tun->lock);
424                 if (!tun_flow_find(head, rxhash) &&
425                     tun->flow_count < MAX_TAP_FLOWS)
426                         tun_flow_create(tun, head, rxhash, queue_index);
427 
428                 if (!timer_pending(&tun->flow_gc_timer))
429                         mod_timer(&tun->flow_gc_timer,
430                                   round_jiffies_up(jiffies + delay));
431                 spin_unlock_bh(&tun->lock);
432         }
433 
434 unlock:
435         rcu_read_unlock();
436 }
437 
438 /**
439  * Save the hash received in the stack receive path and update the
440  * flow_hash table accordingly.
441  */
442 static inline void tun_flow_save_rps_rxhash(struct tun_flow_entry *e, u32 hash)
443 {
444         if (unlikely(e->rps_rxhash != hash))
445                 e->rps_rxhash = hash;
446 }
447 
448 /* We try to identify a flow through its rxhash first. The reason that
449  * we do not check rxq no. is because some cards(e.g 82599), chooses
450  * the rxq based on the txq where the last packet of the flow comes. As
451  * the userspace application move between processors, we may get a
452  * different rxq no. here. If we could not get rxhash, then we would
453  * hope the rxq no. may help here.
454  */
455 static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb,
456                             void *accel_priv, select_queue_fallback_t fallback)
457 {
458         struct tun_struct *tun = netdev_priv(dev);
459         struct tun_flow_entry *e;
460         u32 txq = 0;
461         u32 numqueues = 0;
462 
463         rcu_read_lock();
464         numqueues = ACCESS_ONCE(tun->numqueues);
465 
466         txq = skb_get_hash(skb);
467         if (txq) {
468                 e = tun_flow_find(&tun->flows[tun_hashfn(txq)], txq);
469                 if (e) {
470                         tun_flow_save_rps_rxhash(e, txq);
471                         txq = e->queue_index;
472                 } else
473                         /* use multiply and shift instead of expensive divide */
474                         txq = ((u64)txq * numqueues) >> 32;
475         } else if (likely(skb_rx_queue_recorded(skb))) {
476                 txq = skb_get_rx_queue(skb);
477                 while (unlikely(txq >= numqueues))
478                         txq -= numqueues;
479         }
480 
481         rcu_read_unlock();
482         return txq;
483 }
484 
485 static inline bool tun_not_capable(struct tun_struct *tun)
486 {
487         const struct cred *cred = current_cred();
488         struct net *net = dev_net(tun->dev);
489 
490         return ((uid_valid(tun->owner) && !uid_eq(cred->euid, tun->owner)) ||
491                   (gid_valid(tun->group) && !in_egroup_p(tun->group))) &&
492                 !ns_capable(net->user_ns, CAP_NET_ADMIN);
493 }
494 
495 static void tun_set_real_num_queues(struct tun_struct *tun)
496 {
497         netif_set_real_num_tx_queues(tun->dev, tun->numqueues);
498         netif_set_real_num_rx_queues(tun->dev, tun->numqueues);
499 }
500 
501 static void tun_disable_queue(struct tun_struct *tun, struct tun_file *tfile)
502 {
503         tfile->detached = tun;
504         list_add_tail(&tfile->next, &tun->disabled);
505         ++tun->numdisabled;
506 }
507 
508 static struct tun_struct *tun_enable_queue(struct tun_file *tfile)
509 {
510         struct tun_struct *tun = tfile->detached;
511 
512         tfile->detached = NULL;
513         list_del_init(&tfile->next);
514         --tun->numdisabled;
515         return tun;
516 }
517 
518 static void tun_queue_purge(struct tun_file *tfile)
519 {
520         struct sk_buff *skb;
521 
522         while ((skb = skb_array_consume(&tfile->tx_array)) != NULL)
523                 kfree_skb(skb);
524 
525         skb_queue_purge(&tfile->sk.sk_error_queue);
526 }
527 
528 static void __tun_detach(struct tun_file *tfile, bool clean)
529 {
530         struct tun_file *ntfile;
531         struct tun_struct *tun;
532 
533         tun = rtnl_dereference(tfile->tun);
534 
535         if (tun && !tfile->detached) {
536                 u16 index = tfile->queue_index;
537                 BUG_ON(index >= tun->numqueues);
538 
539                 rcu_assign_pointer(tun->tfiles[index],
540                                    tun->tfiles[tun->numqueues - 1]);
541                 ntfile = rtnl_dereference(tun->tfiles[index]);
542                 ntfile->queue_index = index;
543 
544                 --tun->numqueues;
545                 if (clean) {
546                         RCU_INIT_POINTER(tfile->tun, NULL);
547                         sock_put(&tfile->sk);
548                 } else
549                         tun_disable_queue(tun, tfile);
550 
551                 synchronize_net();
552                 tun_flow_delete_by_queue(tun, tun->numqueues + 1);
553                 /* Drop read queue */
554                 tun_queue_purge(tfile);
555                 tun_set_real_num_queues(tun);
556         } else if (tfile->detached && clean) {
557                 tun = tun_enable_queue(tfile);
558                 sock_put(&tfile->sk);
559         }
560 
561         if (clean) {
562                 if (tun && tun->numqueues == 0 && tun->numdisabled == 0) {
563                         netif_carrier_off(tun->dev);
564 
565                         if (!(tun->flags & IFF_PERSIST) &&
566                             tun->dev->reg_state == NETREG_REGISTERED)
567                                 unregister_netdevice(tun->dev);
568                 }
569                 if (tun)
570                         skb_array_cleanup(&tfile->tx_array);
571                 sock_put(&tfile->sk);
572         }
573 }
574 
575 static void tun_detach(struct tun_file *tfile, bool clean)
576 {
577         rtnl_lock();
578         __tun_detach(tfile, clean);
579         rtnl_unlock();
580 }
581 
582 static void tun_detach_all(struct net_device *dev)
583 {
584         struct tun_struct *tun = netdev_priv(dev);
585         struct tun_file *tfile, *tmp;
586         int i, n = tun->numqueues;
587 
588         for (i = 0; i < n; i++) {
589                 tfile = rtnl_dereference(tun->tfiles[i]);
590                 BUG_ON(!tfile);
591                 tfile->socket.sk->sk_shutdown = RCV_SHUTDOWN;
592                 tfile->socket.sk->sk_data_ready(tfile->socket.sk);
593                 RCU_INIT_POINTER(tfile->tun, NULL);
594                 --tun->numqueues;
595         }
596         list_for_each_entry(tfile, &tun->disabled, next) {
597                 tfile->socket.sk->sk_shutdown = RCV_SHUTDOWN;
598                 tfile->socket.sk->sk_data_ready(tfile->socket.sk);
599                 RCU_INIT_POINTER(tfile->tun, NULL);
600         }
601         BUG_ON(tun->numqueues != 0);
602 
603         synchronize_net();
604         for (i = 0; i < n; i++) {
605                 tfile = rtnl_dereference(tun->tfiles[i]);
606                 /* Drop read queue */
607                 tun_queue_purge(tfile);
608                 sock_put(&tfile->sk);
609         }
610         list_for_each_entry_safe(tfile, tmp, &tun->disabled, next) {
611                 tun_enable_queue(tfile);
612                 tun_queue_purge(tfile);
613                 sock_put(&tfile->sk);
614         }
615         BUG_ON(tun->numdisabled != 0);
616 
617         if (tun->flags & IFF_PERSIST)
618                 module_put(THIS_MODULE);
619 }
620 
621 static int tun_attach(struct tun_struct *tun, struct file *file, bool skip_filter)
622 {
623         struct tun_file *tfile = file->private_data;
624         struct net_device *dev = tun->dev;
625         int err;
626 
627         err = security_tun_dev_attach(tfile->socket.sk, tun->security);
628         if (err < 0)
629                 goto out;
630 
631         err = -EINVAL;
632         if (rtnl_dereference(tfile->tun) && !tfile->detached)
633                 goto out;
634 
635         err = -EBUSY;
636         if (!(tun->flags & IFF_MULTI_QUEUE) && tun->numqueues == 1)
637                 goto out;
638 
639         err = -E2BIG;
640         if (!tfile->detached &&
641             tun->numqueues + tun->numdisabled == MAX_TAP_QUEUES)
642                 goto out;
643 
644         err = 0;
645 
646         /* Re-attach the filter to persist device */
647         if (!skip_filter && (tun->filter_attached == true)) {
648                 lock_sock(tfile->socket.sk);
649                 err = sk_attach_filter(&tun->fprog, tfile->socket.sk);
650                 release_sock(tfile->socket.sk);
651                 if (!err)
652                         goto out;
653         }
654 
655         if (!tfile->detached &&
656             skb_array_init(&tfile->tx_array, dev->tx_queue_len, GFP_KERNEL)) {
657                 err = -ENOMEM;
658                 goto out;
659         }
660 
661         tfile->queue_index = tun->numqueues;
662         tfile->socket.sk->sk_shutdown &= ~RCV_SHUTDOWN;
663         rcu_assign_pointer(tfile->tun, tun);
664         rcu_assign_pointer(tun->tfiles[tun->numqueues], tfile);
665         tun->numqueues++;
666 
667         if (tfile->detached)
668                 tun_enable_queue(tfile);
669         else
670                 sock_hold(&tfile->sk);
671 
672         tun_set_real_num_queues(tun);
673 
674         /* device is allowed to go away first, so no need to hold extra
675          * refcnt.
676          */
677 
678 out:
679         return err;
680 }
681 
682 static struct tun_struct *__tun_get(struct tun_file *tfile)
683 {
684         struct tun_struct *tun;
685 
686         rcu_read_lock();
687         tun = rcu_dereference(tfile->tun);
688         if (tun)
689                 dev_hold(tun->dev);
690         rcu_read_unlock();
691 
692         return tun;
693 }
694 
695 static struct tun_struct *tun_get(struct file *file)
696 {
697         return __tun_get(file->private_data);
698 }
699 
700 static void tun_put(struct tun_struct *tun)
701 {
702         dev_put(tun->dev);
703 }
704 
705 /* TAP filtering */
706 static void addr_hash_set(u32 *mask, const u8 *addr)
707 {
708         int n = ether_crc(ETH_ALEN, addr) >> 26;
709         mask[n >> 5] |= (1 << (n & 31));
710 }
711 
712 static unsigned int addr_hash_test(const u32 *mask, const u8 *addr)
713 {
714         int n = ether_crc(ETH_ALEN, addr) >> 26;
715         return mask[n >> 5] & (1 << (n & 31));
716 }
717 
718 static int update_filter(struct tap_filter *filter, void __user *arg)
719 {
720         struct { u8 u[ETH_ALEN]; } *addr;
721         struct tun_filter uf;
722         int err, alen, n, nexact;
723 
724         if (copy_from_user(&uf, arg, sizeof(uf)))
725                 return -EFAULT;
726 
727         if (!uf.count) {
728                 /* Disabled */
729                 filter->count = 0;
730                 return 0;
731         }
732 
733         alen = ETH_ALEN * uf.count;
734         addr = memdup_user(arg + sizeof(uf), alen);
735         if (IS_ERR(addr))
736                 return PTR_ERR(addr);
737 
738         /* The filter is updated without holding any locks. Which is
739          * perfectly safe. We disable it first and in the worst
740          * case we'll accept a few undesired packets. */
741         filter->count = 0;
742         wmb();
743 
744         /* Use first set of addresses as an exact filter */
745         for (n = 0; n < uf.count && n < FLT_EXACT_COUNT; n++)
746                 memcpy(filter->addr[n], addr[n].u, ETH_ALEN);
747 
748         nexact = n;
749 
750         /* Remaining multicast addresses are hashed,
751          * unicast will leave the filter disabled. */
752         memset(filter->mask, 0, sizeof(filter->mask));
753         for (; n < uf.count; n++) {
754                 if (!is_multicast_ether_addr(addr[n].u)) {
755                         err = 0; /* no filter */
756                         goto free_addr;
757                 }
758                 addr_hash_set(filter->mask, addr[n].u);
759         }
760 
761         /* For ALLMULTI just set the mask to all ones.
762          * This overrides the mask populated above. */
763         if ((uf.flags & TUN_FLT_ALLMULTI))
764                 memset(filter->mask, ~0, sizeof(filter->mask));
765 
766         /* Now enable the filter */
767         wmb();
768         filter->count = nexact;
769 
770         /* Return the number of exact filters */
771         err = nexact;
772 free_addr:
773         kfree(addr);
774         return err;
775 }
776 
777 /* Returns: 0 - drop, !=0 - accept */
778 static int run_filter(struct tap_filter *filter, const struct sk_buff *skb)
779 {
780         /* Cannot use eth_hdr(skb) here because skb_mac_hdr() is incorrect
781          * at this point. */
782         struct ethhdr *eh = (struct ethhdr *) skb->data;
783         int i;
784 
785         /* Exact match */
786         for (i = 0; i < filter->count; i++)
787                 if (ether_addr_equal(eh->h_dest, filter->addr[i]))
788                         return 1;
789 
790         /* Inexact match (multicast only) */
791         if (is_multicast_ether_addr(eh->h_dest))
792                 return addr_hash_test(filter->mask, eh->h_dest);
793 
794         return 0;
795 }
796 
797 /*
798  * Checks whether the packet is accepted or not.
799  * Returns: 0 - drop, !=0 - accept
800  */
801 static int check_filter(struct tap_filter *filter, const struct sk_buff *skb)
802 {
803         if (!filter->count)
804                 return 1;
805 
806         return run_filter(filter, skb);
807 }
808 
809 /* Network device part of the driver */
810 
811 static const struct ethtool_ops tun_ethtool_ops;
812 
813 /* Net device detach from fd. */
814 static void tun_net_uninit(struct net_device *dev)
815 {
816         tun_detach_all(dev);
817 }
818 
819 /* Net device open. */
820 static int tun_net_open(struct net_device *dev)
821 {
822         netif_tx_start_all_queues(dev);
823         return 0;
824 }
825 
826 /* Net device close. */
827 static int tun_net_close(struct net_device *dev)
828 {
829         netif_tx_stop_all_queues(dev);
830         return 0;
831 }
832 
833 /* Net device start xmit */
834 static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
835 {
836         struct tun_struct *tun = netdev_priv(dev);
837         int txq = skb->queue_mapping;
838         struct tun_file *tfile;
839         u32 numqueues = 0;
840 
841         rcu_read_lock();
842         tfile = rcu_dereference(tun->tfiles[txq]);
843         numqueues = ACCESS_ONCE(tun->numqueues);
844 
845         /* Drop packet if interface is not attached */
846         if (txq >= numqueues)
847                 goto drop;
848 
849 #ifdef CONFIG_RPS
850         if (numqueues == 1 && static_key_false(&rps_needed)) {
851                 /* Select queue was not called for the skbuff, so we extract the
852                  * RPS hash and save it into the flow_table here.
853                  */
854                 __u32 rxhash;
855 
856                 rxhash = skb_get_hash(skb);
857                 if (rxhash) {
858                         struct tun_flow_entry *e;
859                         e = tun_flow_find(&tun->flows[tun_hashfn(rxhash)],
860                                         rxhash);
861                         if (e)
862                                 tun_flow_save_rps_rxhash(e, rxhash);
863                 }
864         }
865 #endif
866 
867         tun_debug(KERN_INFO, tun, "tun_net_xmit %d\n", skb->len);
868 
869         BUG_ON(!tfile);
870 
871         /* Drop if the filter does not like it.
872          * This is a noop if the filter is disabled.
873          * Filter can be enabled only for the TAP devices. */
874         if (!check_filter(&tun->txflt, skb))
875                 goto drop;
876 
877         if (tfile->socket.sk->sk_filter &&
878             sk_filter(tfile->socket.sk, skb))
879                 goto drop;
880 
881         if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC)))
882                 goto drop;
883 
884         skb_tx_timestamp(skb);
885 
886         /* Orphan the skb - required as we might hang on to it
887          * for indefinite time.
888          */
889         skb_orphan(skb);
890 
891         nf_reset(skb);
892 
893         if (skb_array_produce(&tfile->tx_array, skb))
894                 goto drop;
895 
896         /* Notify and wake up reader process */
897         if (tfile->flags & TUN_FASYNC)
898                 kill_fasync(&tfile->fasync, SIGIO, POLL_IN);
899         tfile->socket.sk->sk_data_ready(tfile->socket.sk);
900 
901         rcu_read_unlock();
902         return NETDEV_TX_OK;
903 
904 drop:
905         this_cpu_inc(tun->pcpu_stats->tx_dropped);
906         skb_tx_error(skb);
907         kfree_skb(skb);
908         rcu_read_unlock();
909         return NET_XMIT_DROP;
910 }
911 
912 static void tun_net_mclist(struct net_device *dev)
913 {
914         /*
915          * This callback is supposed to deal with mc filter in
916          * _rx_ path and has nothing to do with the _tx_ path.
917          * In rx path we always accept everything userspace gives us.
918          */
919 }
920 
921 static netdev_features_t tun_net_fix_features(struct net_device *dev,
922         netdev_features_t features)
923 {
924         struct tun_struct *tun = netdev_priv(dev);
925 
926         return (features & tun->set_features) | (features & ~TUN_USER_FEATURES);
927 }
928 #ifdef CONFIG_NET_POLL_CONTROLLER
929 static void tun_poll_controller(struct net_device *dev)
930 {
931         /*
932          * Tun only receives frames when:
933          * 1) the char device endpoint gets data from user space
934          * 2) the tun socket gets a sendmsg call from user space
935          * Since both of those are synchronous operations, we are guaranteed
936          * never to have pending data when we poll for it
937          * so there is nothing to do here but return.
938          * We need this though so netpoll recognizes us as an interface that
939          * supports polling, which enables bridge devices in virt setups to
940          * still use netconsole
941          */
942         return;
943 }
944 #endif
945 
946 static void tun_set_headroom(struct net_device *dev, int new_hr)
947 {
948         struct tun_struct *tun = netdev_priv(dev);
949 
950         if (new_hr < NET_SKB_PAD)
951                 new_hr = NET_SKB_PAD;
952 
953         tun->align = new_hr;
954 }
955 
956 static struct rtnl_link_stats64 *
957 tun_net_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
958 {
959         u32 rx_dropped = 0, tx_dropped = 0, rx_frame_errors = 0;
960         struct tun_struct *tun = netdev_priv(dev);
961         struct tun_pcpu_stats *p;
962         int i;
963 
964         for_each_possible_cpu(i) {
965                 u64 rxpackets, rxbytes, txpackets, txbytes;
966                 unsigned int start;
967 
968                 p = per_cpu_ptr(tun->pcpu_stats, i);
969                 do {
970                         start = u64_stats_fetch_begin(&p->syncp);
971                         rxpackets       = p->rx_packets;
972                         rxbytes         = p->rx_bytes;
973                         txpackets       = p->tx_packets;
974                         txbytes         = p->tx_bytes;
975                 } while (u64_stats_fetch_retry(&p->syncp, start));
976 
977                 stats->rx_packets       += rxpackets;
978                 stats->rx_bytes         += rxbytes;
979                 stats->tx_packets       += txpackets;
980                 stats->tx_bytes         += txbytes;
981 
982                 /* u32 counters */
983                 rx_dropped      += p->rx_dropped;
984                 rx_frame_errors += p->rx_frame_errors;
985                 tx_dropped      += p->tx_dropped;
986         }
987         stats->rx_dropped  = rx_dropped;
988         stats->rx_frame_errors = rx_frame_errors;
989         stats->tx_dropped = tx_dropped;
990         return stats;
991 }
992 
993 static const struct net_device_ops tun_netdev_ops = {
994         .ndo_uninit             = tun_net_uninit,
995         .ndo_open               = tun_net_open,
996         .ndo_stop               = tun_net_close,
997         .ndo_start_xmit         = tun_net_xmit,
998         .ndo_fix_features       = tun_net_fix_features,
999         .ndo_select_queue       = tun_select_queue,
1000 #ifdef CONFIG_NET_POLL_CONTROLLER
1001         .ndo_poll_controller    = tun_poll_controller,
1002 #endif
1003         .ndo_set_rx_headroom    = tun_set_headroom,
1004         .ndo_get_stats64        = tun_net_get_stats64,
1005 };
1006 
1007 static const struct net_device_ops tap_netdev_ops = {
1008         .ndo_uninit             = tun_net_uninit,
1009         .ndo_open               = tun_net_open,
1010         .ndo_stop               = tun_net_close,
1011         .ndo_start_xmit         = tun_net_xmit,
1012         .ndo_fix_features       = tun_net_fix_features,
1013         .ndo_set_rx_mode        = tun_net_mclist,
1014         .ndo_set_mac_address    = eth_mac_addr,
1015         .ndo_validate_addr      = eth_validate_addr,
1016         .ndo_select_queue       = tun_select_queue,
1017 #ifdef CONFIG_NET_POLL_CONTROLLER
1018         .ndo_poll_controller    = tun_poll_controller,
1019 #endif
1020         .ndo_features_check     = passthru_features_check,
1021         .ndo_set_rx_headroom    = tun_set_headroom,
1022         .ndo_get_stats64        = tun_net_get_stats64,
1023 };
1024 
1025 static void tun_flow_init(struct tun_struct *tun)
1026 {
1027         int i;
1028 
1029         for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++)
1030                 INIT_HLIST_HEAD(&tun->flows[i]);
1031 
1032         tun->ageing_time = TUN_FLOW_EXPIRE;
1033         setup_timer(&tun->flow_gc_timer, tun_flow_cleanup, (unsigned long)tun);
1034         mod_timer(&tun->flow_gc_timer,
1035                   round_jiffies_up(jiffies + tun->ageing_time));
1036 }
1037 
1038 static void tun_flow_uninit(struct tun_struct *tun)
1039 {
1040         del_timer_sync(&tun->flow_gc_timer);
1041         tun_flow_flush(tun);
1042 }
1043 
1044 #define MIN_MTU 68
1045 #define MAX_MTU 65535
1046 
1047 /* Initialize net device. */
1048 static void tun_net_init(struct net_device *dev)
1049 {
1050         struct tun_struct *tun = netdev_priv(dev);
1051 
1052         switch (tun->flags & TUN_TYPE_MASK) {
1053         case IFF_TUN:
1054                 dev->netdev_ops = &tun_netdev_ops;
1055 
1056                 /* Point-to-Point TUN Device */
1057                 dev->hard_header_len = 0;
1058                 dev->addr_len = 0;
1059                 dev->mtu = 1500;
1060 
1061                 /* Zero header length */
1062                 dev->type = ARPHRD_NONE;
1063                 dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
1064                 break;
1065 
1066         case IFF_TAP:
1067                 dev->netdev_ops = &tap_netdev_ops;
1068                 /* Ethernet TAP Device */
1069                 ether_setup(dev);
1070                 dev->priv_flags &= ~IFF_TX_SKB_SHARING;
1071                 dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
1072 
1073                 eth_hw_addr_random(dev);
1074 
1075                 break;
1076         }
1077 
1078         dev->min_mtu = MIN_MTU;
1079         dev->max_mtu = MAX_MTU - dev->hard_header_len;
1080 }
1081 
1082 /* Character device part */
1083 
1084 /* Poll */
1085 static unsigned int tun_chr_poll(struct file *file, poll_table *wait)
1086 {
1087         struct tun_file *tfile = file->private_data;
1088         struct tun_struct *tun = __tun_get(tfile);
1089         struct sock *sk;
1090         unsigned int mask = 0;
1091 
1092         if (!tun)
1093                 return POLLERR;
1094 
1095         sk = tfile->socket.sk;
1096 
1097         tun_debug(KERN_INFO, tun, "tun_chr_poll\n");
1098 
1099         poll_wait(file, sk_sleep(sk), wait);
1100 
1101         if (!skb_array_empty(&tfile->tx_array))
1102                 mask |= POLLIN | POLLRDNORM;
1103 
1104         if (sock_writeable(sk) ||
1105             (!test_and_set_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags) &&
1106              sock_writeable(sk)))
1107                 mask |= POLLOUT | POLLWRNORM;
1108 
1109         if (tun->dev->reg_state != NETREG_REGISTERED)
1110                 mask = POLLERR;
1111 
1112         tun_put(tun);
1113         return mask;
1114 }
1115 
1116 /* prepad is the amount to reserve at front.  len is length after that.
1117  * linear is a hint as to how much to copy (usually headers). */
1118 static struct sk_buff *tun_alloc_skb(struct tun_file *tfile,
1119                                      size_t prepad, size_t len,
1120                                      size_t linear, int noblock)
1121 {
1122         struct sock *sk = tfile->socket.sk;
1123         struct sk_buff *skb;
1124         int err;
1125 
1126         /* Under a page?  Don't bother with paged skb. */
1127         if (prepad + len < PAGE_SIZE || !linear)
1128                 linear = len;
1129 
1130         skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
1131                                    &err, 0);
1132         if (!skb)
1133                 return ERR_PTR(err);
1134 
1135         skb_reserve(skb, prepad);
1136         skb_put(skb, linear);
1137         skb->data_len = len - linear;
1138         skb->len += len - linear;
1139 
1140         return skb;
1141 }
1142 
1143 /* Get packet from user space buffer */
1144 static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
1145                             void *msg_control, struct iov_iter *from,
1146                             int noblock)
1147 {
1148         struct tun_pi pi = { 0, cpu_to_be16(ETH_P_IP) };
1149         struct sk_buff *skb;
1150         size_t total_len = iov_iter_count(from);
1151         size_t len = total_len, align = tun->align, linear;
1152         struct virtio_net_hdr gso = { 0 };
1153         struct tun_pcpu_stats *stats;
1154         int good_linear;
1155         int copylen;
1156         bool zerocopy = false;
1157         int err;
1158         u32 rxhash;
1159 
1160         if (!(tun->dev->flags & IFF_UP))
1161                 return -EIO;
1162 
1163         if (!(tun->flags & IFF_NO_PI)) {
1164                 if (len < sizeof(pi))
1165                         return -EINVAL;
1166                 len -= sizeof(pi);
1167 
1168                 if (!copy_from_iter_full(&pi, sizeof(pi), from))
1169                         return -EFAULT;
1170         }
1171 
1172         if (tun->flags & IFF_VNET_HDR) {
1173                 int vnet_hdr_sz = READ_ONCE(tun->vnet_hdr_sz);
1174 
1175                 if (len < vnet_hdr_sz)
1176                         return -EINVAL;
1177                 len -= vnet_hdr_sz;
1178 
1179                 if (!copy_from_iter_full(&gso, sizeof(gso), from))
1180                         return -EFAULT;
1181 
1182                 if ((gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
1183                     tun16_to_cpu(tun, gso.csum_start) + tun16_to_cpu(tun, gso.csum_offset) + 2 > tun16_to_cpu(tun, gso.hdr_len))
1184                         gso.hdr_len = cpu_to_tun16(tun, tun16_to_cpu(tun, gso.csum_start) + tun16_to_cpu(tun, gso.csum_offset) + 2);
1185 
1186                 if (tun16_to_cpu(tun, gso.hdr_len) > len)
1187                         return -EINVAL;
1188                 iov_iter_advance(from, vnet_hdr_sz - sizeof(gso));
1189         }
1190 
1191         if ((tun->flags & TUN_TYPE_MASK) == IFF_TAP) {
1192                 align += NET_IP_ALIGN;
1193                 if (unlikely(len < ETH_HLEN ||
1194                              (gso.hdr_len && tun16_to_cpu(tun, gso.hdr_len) < ETH_HLEN)))
1195                         return -EINVAL;
1196         }
1197 
1198         good_linear = SKB_MAX_HEAD(align);
1199 
1200         if (msg_control) {
1201                 struct iov_iter i = *from;
1202 
1203                 /* There are 256 bytes to be copied in skb, so there is
1204                  * enough room for skb expand head in case it is used.
1205                  * The rest of the buffer is mapped from userspace.
1206                  */
1207                 copylen = gso.hdr_len ? tun16_to_cpu(tun, gso.hdr_len) : GOODCOPY_LEN;
1208                 if (copylen > good_linear)
1209                         copylen = good_linear;
1210                 linear = copylen;
1211                 iov_iter_advance(&i, copylen);
1212                 if (iov_iter_npages(&i, INT_MAX) <= MAX_SKB_FRAGS)
1213                         zerocopy = true;
1214         }
1215 
1216         if (!zerocopy) {
1217                 copylen = len;
1218                 if (tun16_to_cpu(tun, gso.hdr_len) > good_linear)
1219                         linear = good_linear;
1220                 else
1221                         linear = tun16_to_cpu(tun, gso.hdr_len);
1222         }
1223 
1224         skb = tun_alloc_skb(tfile, align, copylen, linear, noblock);
1225         if (IS_ERR(skb)) {
1226                 if (PTR_ERR(skb) != -EAGAIN)
1227                         this_cpu_inc(tun->pcpu_stats->rx_dropped);
1228                 return PTR_ERR(skb);
1229         }
1230 
1231         if (zerocopy)
1232                 err = zerocopy_sg_from_iter(skb, from);
1233         else
1234                 err = skb_copy_datagram_from_iter(skb, 0, from, len);
1235 
1236         if (err) {
1237                 this_cpu_inc(tun->pcpu_stats->rx_dropped);
1238                 kfree_skb(skb);
1239                 return -EFAULT;
1240         }
1241 
1242         if (virtio_net_hdr_to_skb(skb, &gso, tun_is_little_endian(tun))) {
1243                 this_cpu_inc(tun->pcpu_stats->rx_frame_errors);
1244                 kfree_skb(skb);
1245                 return -EINVAL;
1246         }
1247 
1248         switch (tun->flags & TUN_TYPE_MASK) {
1249         case IFF_TUN:
1250                 if (tun->flags & IFF_NO_PI) {
1251                         switch (skb->data[0] & 0xf0) {
1252                         case 0x40:
1253                                 pi.proto = htons(ETH_P_IP);
1254                                 break;
1255                         case 0x60:
1256                                 pi.proto = htons(ETH_P_IPV6);
1257                                 break;
1258                         default:
1259                                 this_cpu_inc(tun->pcpu_stats->rx_dropped);
1260                                 kfree_skb(skb);
1261                                 return -EINVAL;
1262                         }
1263                 }
1264 
1265                 skb_reset_mac_header(skb);
1266                 skb->protocol = pi.proto;
1267                 skb->dev = tun->dev;
1268                 break;
1269         case IFF_TAP:
1270                 skb->protocol = eth_type_trans(skb, tun->dev);
1271                 break;
1272         }
1273 
1274         /* copy skb_ubuf_info for callback when skb has no error */
1275         if (zerocopy) {
1276                 skb_shinfo(skb)->destructor_arg = msg_control;
1277                 skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
1278                 skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
1279         } else if (msg_control) {
1280                 struct ubuf_info *uarg = msg_control;
1281                 uarg->callback(uarg, false);
1282         }
1283 
1284         skb_reset_network_header(skb);
1285         skb_probe_transport_header(skb, 0);
1286 
1287         rxhash = skb_get_hash(skb);
1288 #ifndef CONFIG_4KSTACKS
1289         local_bh_disable();
1290         netif_receive_skb(skb);
1291         local_bh_enable();
1292 #else
1293         netif_rx_ni(skb);
1294 #endif
1295 
1296         stats = get_cpu_ptr(tun->pcpu_stats);
1297         u64_stats_update_begin(&stats->syncp);
1298         stats->rx_packets++;
1299         stats->rx_bytes += len;
1300         u64_stats_update_end(&stats->syncp);
1301         put_cpu_ptr(stats);
1302 
1303         tun_flow_update(tun, rxhash, tfile);
1304         return total_len;
1305 }
1306 
1307 static ssize_t tun_chr_write_iter(struct kiocb *iocb, struct iov_iter *from)
1308 {
1309         struct file *file = iocb->ki_filp;
1310         struct tun_struct *tun = tun_get(file);
1311         struct tun_file *tfile = file->private_data;
1312         ssize_t result;
1313 
1314         if (!tun)
1315                 return -EBADFD;
1316 
1317         result = tun_get_user(tun, tfile, NULL, from, file->f_flags & O_NONBLOCK);
1318 
1319         tun_put(tun);
1320         return result;
1321 }
1322 
1323 /* Put packet to the user space buffer */
1324 static ssize_t tun_put_user(struct tun_struct *tun,
1325                             struct tun_file *tfile,
1326                             struct sk_buff *skb,
1327                             struct iov_iter *iter)
1328 {
1329         struct tun_pi pi = { 0, skb->protocol };
1330         struct tun_pcpu_stats *stats;
1331         ssize_t total;
1332         int vlan_offset = 0;
1333         int vlan_hlen = 0;
1334         int vnet_hdr_sz = 0;
1335 
1336         if (skb_vlan_tag_present(skb))
1337                 vlan_hlen = VLAN_HLEN;
1338 
1339         if (tun->flags & IFF_VNET_HDR)
1340                 vnet_hdr_sz = READ_ONCE(tun->vnet_hdr_sz);
1341 
1342         total = skb->len + vlan_hlen + vnet_hdr_sz;
1343 
1344         if (!(tun->flags & IFF_NO_PI)) {
1345                 if (iov_iter_count(iter) < sizeof(pi))
1346                         return -EINVAL;
1347 
1348                 total += sizeof(pi);
1349                 if (iov_iter_count(iter) < total) {
1350                         /* Packet will be striped */
1351                         pi.flags |= TUN_PKT_STRIP;
1352                 }
1353 
1354                 if (copy_to_iter(&pi, sizeof(pi), iter) != sizeof(pi))
1355                         return -EFAULT;
1356         }
1357 
1358         if (vnet_hdr_sz) {
1359                 struct virtio_net_hdr gso;
1360 
1361                 if (iov_iter_count(iter) < vnet_hdr_sz)
1362                         return -EINVAL;
1363 
1364                 if (virtio_net_hdr_from_skb(skb, &gso,
1365                                             tun_is_little_endian(tun), true)) {
1366                         struct skb_shared_info *sinfo = skb_shinfo(skb);
1367                         pr_err("unexpected GSO type: "
1368                                "0x%x, gso_size %d, hdr_len %d\n",
1369                                sinfo->gso_type, tun16_to_cpu(tun, gso.gso_size),
1370                                tun16_to_cpu(tun, gso.hdr_len));
1371                         print_hex_dump(KERN_ERR, "tun: ",
1372                                        DUMP_PREFIX_NONE,
1373                                        16, 1, skb->head,
1374                                        min((int)tun16_to_cpu(tun, gso.hdr_len), 64), true);
1375                         WARN_ON_ONCE(1);
1376                         return -EINVAL;
1377                 }
1378 
1379                 if (copy_to_iter(&gso, sizeof(gso), iter) != sizeof(gso))
1380                         return -EFAULT;
1381 
1382                 iov_iter_advance(iter, vnet_hdr_sz - sizeof(gso));
1383         }
1384 
1385         if (vlan_hlen) {
1386                 int ret;
1387                 struct {
1388                         __be16 h_vlan_proto;
1389                         __be16 h_vlan_TCI;
1390                 } veth;
1391 
1392                 veth.h_vlan_proto = skb->vlan_proto;
1393                 veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
1394 
1395                 vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
1396 
1397                 ret = skb_copy_datagram_iter(skb, 0, iter, vlan_offset);
1398                 if (ret || !iov_iter_count(iter))
1399                         goto done;
1400 
1401                 ret = copy_to_iter(&veth, sizeof(veth), iter);
1402                 if (ret != sizeof(veth) || !iov_iter_count(iter))
1403                         goto done;
1404         }
1405 
1406         skb_copy_datagram_iter(skb, vlan_offset, iter, skb->len - vlan_offset);
1407 
1408 done:
1409         /* caller is in process context, */
1410         stats = get_cpu_ptr(tun->pcpu_stats);
1411         u64_stats_update_begin(&stats->syncp);
1412         stats->tx_packets++;
1413         stats->tx_bytes += skb->len + vlan_hlen;
1414         u64_stats_update_end(&stats->syncp);
1415         put_cpu_ptr(tun->pcpu_stats);
1416 
1417         return total;
1418 }
1419 
1420 static struct sk_buff *tun_ring_recv(struct tun_file *tfile, int noblock,
1421                                      int *err)
1422 {
1423         DECLARE_WAITQUEUE(wait, current);
1424         struct sk_buff *skb = NULL;
1425         int error = 0;
1426 
1427         skb = skb_array_consume(&tfile->tx_array);
1428         if (skb)
1429                 goto out;
1430         if (noblock) {
1431                 error = -EAGAIN;
1432                 goto out;
1433         }
1434 
1435         add_wait_queue(&tfile->wq.wait, &wait);
1436         current->state = TASK_INTERRUPTIBLE;
1437 
1438         while (1) {
1439                 skb = skb_array_consume(&tfile->tx_array);
1440                 if (skb)
1441                         break;
1442                 if (signal_pending(current)) {
1443                         error = -ERESTARTSYS;
1444                         break;
1445                 }
1446                 if (tfile->socket.sk->sk_shutdown & RCV_SHUTDOWN) {
1447                         error = -EFAULT;
1448                         break;
1449                 }
1450 
1451                 schedule();
1452         }
1453 
1454         current->state = TASK_RUNNING;
1455         remove_wait_queue(&tfile->wq.wait, &wait);
1456 
1457 out:
1458         *err = error;
1459         return skb;
1460 }
1461 
1462 static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
1463                            struct iov_iter *to,
1464                            int noblock)
1465 {
1466         struct sk_buff *skb;
1467         ssize_t ret;
1468         int err;
1469 
1470         tun_debug(KERN_INFO, tun, "tun_do_read\n");
1471 
1472         if (!iov_iter_count(to))
1473                 return 0;
1474 
1475         /* Read frames from ring */
1476         skb = tun_ring_recv(tfile, noblock, &err);
1477         if (!skb)
1478                 return err;
1479 
1480         ret = tun_put_user(tun, tfile, skb, to);
1481         if (unlikely(ret < 0))
1482                 kfree_skb(skb);
1483         else
1484                 consume_skb(skb);
1485 
1486         return ret;
1487 }
1488 
1489 static ssize_t tun_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
1490 {
1491         struct file *file = iocb->ki_filp;
1492         struct tun_file *tfile = file->private_data;
1493         struct tun_struct *tun = __tun_get(tfile);
1494         ssize_t len = iov_iter_count(to), ret;
1495 
1496         if (!tun)
1497                 return -EBADFD;
1498         ret = tun_do_read(tun, tfile, to, file->f_flags & O_NONBLOCK);
1499         ret = min_t(ssize_t, ret, len);
1500         if (ret > 0)
1501                 iocb->ki_pos = ret;
1502         tun_put(tun);
1503         return ret;
1504 }
1505 
1506 static void tun_free_netdev(struct net_device *dev)
1507 {
1508         struct tun_struct *tun = netdev_priv(dev);
1509 
1510         BUG_ON(!(list_empty(&tun->disabled)));
1511         free_percpu(tun->pcpu_stats);
1512         tun_flow_uninit(tun);
1513         security_tun_dev_free_security(tun->security);
1514         free_netdev(dev);
1515 }
1516 
1517 static void tun_setup(struct net_device *dev)
1518 {
1519         struct tun_struct *tun = netdev_priv(dev);
1520 
1521         tun->owner = INVALID_UID;
1522         tun->group = INVALID_GID;
1523 
1524         dev->ethtool_ops = &tun_ethtool_ops;
1525         dev->destructor = tun_free_netdev;
1526         /* We prefer our own queue length */
1527         dev->tx_queue_len = TUN_READQ_SIZE;
1528 }
1529 
1530 /* Trivial set of netlink ops to allow deleting tun or tap
1531  * device with netlink.
1532  */
1533 static int tun_validate(struct nlattr *tb[], struct nlattr *data[])
1534 {
1535         return -EINVAL;
1536 }
1537 
1538 static struct rtnl_link_ops tun_link_ops __read_mostly = {
1539         .kind           = DRV_NAME,
1540         .priv_size      = sizeof(struct tun_struct),
1541         .setup          = tun_setup,
1542         .validate       = tun_validate,
1543 };
1544 
1545 static void tun_sock_write_space(struct sock *sk)
1546 {
1547         struct tun_file *tfile;
1548         wait_queue_head_t *wqueue;
1549 
1550         if (!sock_writeable(sk))
1551                 return;
1552 
1553         if (!test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags))
1554                 return;
1555 
1556         wqueue = sk_sleep(sk);
1557         if (wqueue && waitqueue_active(wqueue))
1558                 wake_up_interruptible_sync_poll(wqueue, POLLOUT |
1559                                                 POLLWRNORM | POLLWRBAND);
1560 
1561         tfile = container_of(sk, struct tun_file, sk);
1562         kill_fasync(&tfile->fasync, SIGIO, POLL_OUT);
1563 }
1564 
1565 static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len)
1566 {
1567         int ret;
1568         struct tun_file *tfile = container_of(sock, struct tun_file, socket);
1569         struct tun_struct *tun = __tun_get(tfile);
1570 
1571         if (!tun)
1572                 return -EBADFD;
1573 
1574         ret = tun_get_user(tun, tfile, m->msg_control, &m->msg_iter,
1575                            m->msg_flags & MSG_DONTWAIT);
1576         tun_put(tun);
1577         return ret;
1578 }
1579 
1580 static int tun_recvmsg(struct socket *sock, struct msghdr *m, size_t total_len,
1581                        int flags)
1582 {
1583         struct tun_file *tfile = container_of(sock, struct tun_file, socket);
1584         struct tun_struct *tun = __tun_get(tfile);
1585         int ret;
1586 
1587         if (!tun)
1588                 return -EBADFD;
1589 
1590         if (flags & ~(MSG_DONTWAIT|MSG_TRUNC|MSG_ERRQUEUE)) {
1591                 ret = -EINVAL;
1592                 goto out;
1593         }
1594         if (flags & MSG_ERRQUEUE) {
1595                 ret = sock_recv_errqueue(sock->sk, m, total_len,
1596                                          SOL_PACKET, TUN_TX_TIMESTAMP);
1597                 goto out;
1598         }
1599         ret = tun_do_read(tun, tfile, &m->msg_iter, flags & MSG_DONTWAIT);
1600         if (ret > (ssize_t)total_len) {
1601                 m->msg_flags |= MSG_TRUNC;
1602                 ret = flags & MSG_TRUNC ? ret : total_len;
1603         }
1604 out:
1605         tun_put(tun);
1606         return ret;
1607 }
1608 
1609 static int tun_peek_len(struct socket *sock)
1610 {
1611         struct tun_file *tfile = container_of(sock, struct tun_file, socket);
1612         struct tun_struct *tun;
1613         int ret = 0;
1614 
1615         tun = __tun_get(tfile);
1616         if (!tun)
1617                 return 0;
1618 
1619         ret = skb_array_peek_len(&tfile->tx_array);
1620         tun_put(tun);
1621 
1622         return ret;
1623 }
1624 
1625 /* Ops structure to mimic raw sockets with tun */
1626 static const struct proto_ops tun_socket_ops = {
1627         .peek_len = tun_peek_len,
1628         .sendmsg = tun_sendmsg,
1629         .recvmsg = tun_recvmsg,
1630 };
1631 
1632 static struct proto tun_proto = {
1633         .name           = "tun",
1634         .owner          = THIS_MODULE,
1635         .obj_size       = sizeof(struct tun_file),
1636 };
1637 
1638 static int tun_flags(struct tun_struct *tun)
1639 {
1640         return tun->flags & (TUN_FEATURES | IFF_PERSIST | IFF_TUN | IFF_TAP);
1641 }
1642 
1643 static ssize_t tun_show_flags(struct device *dev, struct device_attribute *attr,
1644                               char *buf)
1645 {
1646         struct tun_struct *tun = netdev_priv(to_net_dev(dev));
1647         return sprintf(buf, "0x%x\n", tun_flags(tun));
1648 }
1649 
1650 static ssize_t tun_show_owner(struct device *dev, struct device_attribute *attr,
1651                               char *buf)
1652 {
1653         struct tun_struct *tun = netdev_priv(to_net_dev(dev));
1654         return uid_valid(tun->owner)?
1655                 sprintf(buf, "%u\n",
1656                         from_kuid_munged(current_user_ns(), tun->owner)):
1657                 sprintf(buf, "-1\n");
1658 }
1659 
1660 static ssize_t tun_show_group(struct device *dev, struct device_attribute *attr,
1661                               char *buf)
1662 {
1663         struct tun_struct *tun = netdev_priv(to_net_dev(dev));
1664         return gid_valid(tun->group) ?
1665                 sprintf(buf, "%u\n",
1666                         from_kgid_munged(current_user_ns(), tun->group)):
1667                 sprintf(buf, "-1\n");
1668 }
1669 
1670 static DEVICE_ATTR(tun_flags, 0444, tun_show_flags, NULL);
1671 static DEVICE_ATTR(owner, 0444, tun_show_owner, NULL);
1672 static DEVICE_ATTR(group, 0444, tun_show_group, NULL);
1673 
1674 static struct attribute *tun_dev_attrs[] = {
1675         &dev_attr_tun_flags.attr,
1676         &dev_attr_owner.attr,
1677         &dev_attr_group.attr,
1678         NULL
1679 };
1680 
1681 static const struct attribute_group tun_attr_group = {
1682         .attrs = tun_dev_attrs
1683 };
1684 
1685 static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
1686 {
1687         struct tun_struct *tun;
1688         struct tun_file *tfile = file->private_data;
1689         struct net_device *dev;
1690         int err;
1691 
1692         if (tfile->detached)
1693                 return -EINVAL;
1694 
1695         dev = __dev_get_by_name(net, ifr->ifr_name);
1696         if (dev) {
1697                 if (ifr->ifr_flags & IFF_TUN_EXCL)
1698                         return -EBUSY;
1699                 if ((ifr->ifr_flags & IFF_TUN) && dev->netdev_ops == &tun_netdev_ops)
1700                         tun = netdev_priv(dev);
1701                 else if ((ifr->ifr_flags & IFF_TAP) && dev->netdev_ops == &tap_netdev_ops)
1702                         tun = netdev_priv(dev);
1703                 else
1704                         return -EINVAL;
1705 
1706                 if (!!(ifr->ifr_flags & IFF_MULTI_QUEUE) !=
1707                     !!(tun->flags & IFF_MULTI_QUEUE))
1708                         return -EINVAL;
1709 
1710                 if (tun_not_capable(tun))
1711                         return -EPERM;
1712                 err = security_tun_dev_open(tun->security);
1713                 if (err < 0)
1714                         return err;
1715 
1716                 err = tun_attach(tun, file, ifr->ifr_flags & IFF_NOFILTER);
1717                 if (err < 0)
1718                         return err;
1719 
1720                 if (tun->flags & IFF_MULTI_QUEUE &&
1721                     (tun->numqueues + tun->numdisabled > 1)) {
1722                         /* One or more queue has already been attached, no need
1723                          * to initialize the device again.
1724                          */
1725                         return 0;
1726                 }
1727         }
1728         else {
1729                 char *name;
1730                 unsigned long flags = 0;
1731                 int queues = ifr->ifr_flags & IFF_MULTI_QUEUE ?
1732                              MAX_TAP_QUEUES : 1;
1733 
1734                 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1735                         return -EPERM;
1736                 err = security_tun_dev_create();
1737                 if (err < 0)
1738                         return err;
1739 
1740                 /* Set dev type */
1741                 if (ifr->ifr_flags & IFF_TUN) {
1742                         /* TUN device */
1743                         flags |= IFF_TUN;
1744                         name = "tun%d";
1745                 } else if (ifr->ifr_flags & IFF_TAP) {
1746                         /* TAP device */
1747                         flags |= IFF_TAP;
1748                         name = "tap%d";
1749                 } else
1750                         return -EINVAL;
1751 
1752                 if (*ifr->ifr_name)
1753                         name = ifr->ifr_name;
1754 
1755                 dev = alloc_netdev_mqs(sizeof(struct tun_struct), name,
1756                                        NET_NAME_UNKNOWN, tun_setup, queues,
1757                                        queues);
1758 
1759                 if (!dev)
1760                         return -ENOMEM;
1761 
1762                 dev_net_set(dev, net);
1763                 dev->rtnl_link_ops = &tun_link_ops;
1764                 dev->ifindex = tfile->ifindex;
1765                 dev->sysfs_groups[0] = &tun_attr_group;
1766 
1767                 tun = netdev_priv(dev);
1768                 tun->dev = dev;
1769                 tun->flags = flags;
1770                 tun->txflt.count = 0;
1771                 tun->vnet_hdr_sz = sizeof(struct virtio_net_hdr);
1772 
1773                 tun->align = NET_SKB_PAD;
1774                 tun->filter_attached = false;
1775                 tun->sndbuf = tfile->socket.sk->sk_sndbuf;
1776 
1777                 tun->pcpu_stats = netdev_alloc_pcpu_stats(struct tun_pcpu_stats);
1778                 if (!tun->pcpu_stats) {
1779                         err = -ENOMEM;
1780                         goto err_free_dev;
1781                 }
1782 
1783                 spin_lock_init(&tun->lock);
1784 
1785                 err = security_tun_dev_alloc_security(&tun->security);
1786                 if (err < 0)
1787                         goto err_free_stat;
1788 
1789                 tun_net_init(dev);
1790                 tun_flow_init(tun);
1791 
1792                 dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST |
1793                                    TUN_USER_FEATURES | NETIF_F_HW_VLAN_CTAG_TX |
1794                                    NETIF_F_HW_VLAN_STAG_TX;
1795                 dev->features = dev->hw_features | NETIF_F_LLTX;
1796                 dev->vlan_features = dev->features &
1797                                      ~(NETIF_F_HW_VLAN_CTAG_TX |
1798                                        NETIF_F_HW_VLAN_STAG_TX);
1799 
1800                 INIT_LIST_HEAD(&tun->disabled);
1801                 err = tun_attach(tun, file, false);
1802                 if (err < 0)
1803                         goto err_free_flow;
1804 
1805                 err = register_netdevice(tun->dev);
1806                 if (err < 0)
1807                         goto err_detach;
1808         }
1809 
1810         netif_carrier_on(tun->dev);
1811 
1812         tun_debug(KERN_INFO, tun, "tun_set_iff\n");
1813 
1814         tun->flags = (tun->flags & ~TUN_FEATURES) |
1815                 (ifr->ifr_flags & TUN_FEATURES);
1816 
1817         /* Make sure persistent devices do not get stuck in
1818          * xoff state.
1819          */
1820         if (netif_running(tun->dev))
1821                 netif_tx_wake_all_queues(tun->dev);
1822 
1823         strcpy(ifr->ifr_name, tun->dev->name);
1824         return 0;
1825 
1826 err_detach:
1827         tun_detach_all(dev);
1828 err_free_flow:
1829         tun_flow_uninit(tun);
1830         security_tun_dev_free_security(tun->security);
1831 err_free_stat:
1832         free_percpu(tun->pcpu_stats);
1833 err_free_dev:
1834         free_netdev(dev);
1835         return err;
1836 }
1837 
1838 static void tun_get_iff(struct net *net, struct tun_struct *tun,
1839                        struct ifreq *ifr)
1840 {
1841         tun_debug(KERN_INFO, tun, "tun_get_iff\n");
1842 
1843         strcpy(ifr->ifr_name, tun->dev->name);
1844 
1845         ifr->ifr_flags = tun_flags(tun);
1846 
1847 }
1848 
1849 /* This is like a cut-down ethtool ops, except done via tun fd so no
1850  * privs required. */
1851 static int set_offload(struct tun_struct *tun, unsigned long arg)
1852 {
1853         netdev_features_t features = 0;
1854 
1855         if (arg & TUN_F_CSUM) {
1856                 features |= NETIF_F_HW_CSUM;
1857                 arg &= ~TUN_F_CSUM;
1858 
1859                 if (arg & (TUN_F_TSO4|TUN_F_TSO6)) {
1860                         if (arg & TUN_F_TSO_ECN) {
1861                                 features |= NETIF_F_TSO_ECN;
1862                                 arg &= ~TUN_F_TSO_ECN;
1863                         }
1864                         if (arg & TUN_F_TSO4)
1865                                 features |= NETIF_F_TSO;
1866                         if (arg & TUN_F_TSO6)
1867                                 features |= NETIF_F_TSO6;
1868                         arg &= ~(TUN_F_TSO4|TUN_F_TSO6);
1869                 }
1870 
1871                 if (arg & TUN_F_UFO) {
1872                         features |= NETIF_F_UFO;
1873                         arg &= ~TUN_F_UFO;
1874                 }
1875         }
1876 
1877         /* This gives the user a way to test for new features in future by
1878          * trying to set them. */
1879         if (arg)
1880                 return -EINVAL;
1881 
1882         tun->set_features = features;
1883         netdev_update_features(tun->dev);
1884 
1885         return 0;
1886 }
1887 
1888 static void tun_detach_filter(struct tun_struct *tun, int n)
1889 {
1890         int i;
1891         struct tun_file *tfile;
1892 
1893         for (i = 0; i < n; i++) {
1894                 tfile = rtnl_dereference(tun->tfiles[i]);
1895                 lock_sock(tfile->socket.sk);
1896                 sk_detach_filter(tfile->socket.sk);
1897                 release_sock(tfile->socket.sk);
1898         }
1899 
1900         tun->filter_attached = false;
1901 }
1902 
1903 static int tun_attach_filter(struct tun_struct *tun)
1904 {
1905         int i, ret = 0;
1906         struct tun_file *tfile;
1907 
1908         for (i = 0; i < tun->numqueues; i++) {
1909                 tfile = rtnl_dereference(tun->tfiles[i]);
1910                 lock_sock(tfile->socket.sk);
1911                 ret = sk_attach_filter(&tun->fprog, tfile->socket.sk);
1912                 release_sock(tfile->socket.sk);
1913                 if (ret) {
1914                         tun_detach_filter(tun, i);
1915                         return ret;
1916                 }
1917         }
1918 
1919         tun->filter_attached = true;
1920         return ret;
1921 }
1922 
1923 static void tun_set_sndbuf(struct tun_struct *tun)
1924 {
1925         struct tun_file *tfile;
1926         int i;
1927 
1928         for (i = 0; i < tun->numqueues; i++) {
1929                 tfile = rtnl_dereference(tun->tfiles[i]);
1930                 tfile->socket.sk->sk_sndbuf = tun->sndbuf;
1931         }
1932 }
1933 
1934 static int tun_set_queue(struct file *file, struct ifreq *ifr)
1935 {
1936         struct tun_file *tfile = file->private_data;
1937         struct tun_struct *tun;
1938         int ret = 0;
1939 
1940         rtnl_lock();
1941 
1942         if (ifr->ifr_flags & IFF_ATTACH_QUEUE) {
1943                 tun = tfile->detached;
1944                 if (!tun) {
1945                         ret = -EINVAL;
1946                         goto unlock;
1947                 }
1948                 ret = security_tun_dev_attach_queue(tun->security);
1949                 if (ret < 0)
1950                         goto unlock;
1951                 ret = tun_attach(tun, file, false);
1952         } else if (ifr->ifr_flags & IFF_DETACH_QUEUE) {
1953                 tun = rtnl_dereference(tfile->tun);
1954                 if (!tun || !(tun->flags & IFF_MULTI_QUEUE) || tfile->detached)
1955                         ret = -EINVAL;
1956                 else
1957                         __tun_detach(tfile, false);
1958         } else
1959                 ret = -EINVAL;
1960 
1961 unlock:
1962         rtnl_unlock();
1963         return ret;
1964 }
1965 
1966 static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
1967                             unsigned long arg, int ifreq_len)
1968 {
1969         struct tun_file *tfile = file->private_data;
1970         struct tun_struct *tun;
1971         void __user* argp = (void __user*)arg;
1972         struct ifreq ifr;
1973         kuid_t owner;
1974         kgid_t group;
1975         int sndbuf;
1976         int vnet_hdr_sz;
1977         unsigned int ifindex;
1978         int le;
1979         int ret;
1980 
1981         if (cmd == TUNSETIFF || cmd == TUNSETQUEUE || _IOC_TYPE(cmd) == SOCK_IOC_TYPE) {
1982                 if (copy_from_user(&ifr, argp, ifreq_len))
1983                         return -EFAULT;
1984         } else {
1985                 memset(&ifr, 0, sizeof(ifr));
1986         }
1987         if (cmd == TUNGETFEATURES) {
1988                 /* Currently this just means: "what IFF flags are valid?".
1989                  * This is needed because we never checked for invalid flags on
1990                  * TUNSETIFF.
1991                  */
1992                 return put_user(IFF_TUN | IFF_TAP | TUN_FEATURES,
1993                                 (unsigned int __user*)argp);
1994         } else if (cmd == TUNSETQUEUE)
1995                 return tun_set_queue(file, &ifr);
1996 
1997         ret = 0;
1998         rtnl_lock();
1999 
2000         tun = __tun_get(tfile);
2001         if (cmd == TUNSETIFF) {
2002                 ret = -EEXIST;
2003                 if (tun)
2004                         goto unlock;
2005 
2006                 ifr.ifr_name[IFNAMSIZ-1] = '\0';
2007 
2008                 ret = tun_set_iff(sock_net(&tfile->sk), file, &ifr);
2009 
2010                 if (ret)
2011                         goto unlock;
2012 
2013                 if (copy_to_user(argp, &ifr, ifreq_len))
2014                         ret = -EFAULT;
2015                 goto unlock;
2016         }
2017         if (cmd == TUNSETIFINDEX) {
2018                 ret = -EPERM;
2019                 if (tun)
2020                         goto unlock;
2021 
2022                 ret = -EFAULT;
2023                 if (copy_from_user(&ifindex, argp, sizeof(ifindex)))
2024                         goto unlock;
2025 
2026                 ret = 0;
2027                 tfile->ifindex = ifindex;
2028                 goto unlock;
2029         }
2030 
2031         ret = -EBADFD;
2032         if (!tun)
2033                 goto unlock;
2034 
2035         tun_debug(KERN_INFO, tun, "tun_chr_ioctl cmd %u\n", cmd);
2036 
2037         ret = 0;
2038         switch (cmd) {
2039         case TUNGETIFF:
2040                 tun_get_iff(current->nsproxy->net_ns, tun, &ifr);
2041 
2042                 if (tfile->detached)
2043                         ifr.ifr_flags |= IFF_DETACH_QUEUE;
2044                 if (!tfile->socket.sk->sk_filter)
2045                         ifr.ifr_flags |= IFF_NOFILTER;
2046 
2047                 if (copy_to_user(argp, &ifr, ifreq_len))
2048                         ret = -EFAULT;
2049                 break;
2050 
2051         case TUNSETNOCSUM:
2052                 /* Disable/Enable checksum */
2053 
2054                 /* [unimplemented] */
2055                 tun_debug(KERN_INFO, tun, "ignored: set checksum %s\n",
2056                           arg ? "disabled" : "enabled");
2057                 break;
2058 
2059         case TUNSETPERSIST:
2060                 /* Disable/Enable persist mode. Keep an extra reference to the
2061                  * module to prevent the module being unprobed.
2062                  */
2063                 if (arg && !(tun->flags & IFF_PERSIST)) {
2064                         tun->flags |= IFF_PERSIST;
2065                         __module_get(THIS_MODULE);
2066                 }
2067                 if (!arg && (tun->flags & IFF_PERSIST)) {
2068                         tun->flags &= ~IFF_PERSIST;
2069                         module_put(THIS_MODULE);
2070                 }
2071 
2072                 tun_debug(KERN_INFO, tun, "persist %s\n",
2073                           arg ? "enabled" : "disabled");
2074                 break;
2075 
2076         case TUNSETOWNER:
2077                 /* Set owner of the device */
2078                 owner = make_kuid(current_user_ns(), arg);
2079                 if (!uid_valid(owner)) {
2080                         ret = -EINVAL;
2081                         break;
2082                 }
2083                 tun->owner = owner;
2084                 tun_debug(KERN_INFO, tun, "owner set to %u\n",
2085                           from_kuid(&init_user_ns, tun->owner));
2086                 break;
2087 
2088         case TUNSETGROUP:
2089                 /* Set group of the device */
2090                 group = make_kgid(current_user_ns(), arg);
2091                 if (!gid_valid(group)) {
2092                         ret = -EINVAL;
2093                         break;
2094                 }
2095                 tun->group = group;
2096                 tun_debug(KERN_INFO, tun, "group set to %u\n",
2097                           from_kgid(&init_user_ns, tun->group));
2098                 break;
2099 
2100         case TUNSETLINK:
2101                 /* Only allow setting the type when the interface is down */
2102                 if (tun->dev->flags & IFF_UP) {
2103                         tun_debug(KERN_INFO, tun,
2104                                   "Linktype set failed because interface is up\n");
2105                         ret = -EBUSY;
2106                 } else {
2107                         tun->dev->type = (int) arg;
2108                         tun_debug(KERN_INFO, tun, "linktype set to %d\n",
2109                                   tun->dev->type);
2110                         ret = 0;
2111                 }
2112                 break;
2113 
2114 #ifdef TUN_DEBUG
2115         case TUNSETDEBUG:
2116                 tun->debug = arg;
2117                 break;
2118 #endif
2119         case TUNSETOFFLOAD:
2120                 ret = set_offload(tun, arg);
2121                 break;
2122 
2123         case TUNSETTXFILTER:
2124                 /* Can be set only for TAPs */
2125                 ret = -EINVAL;
2126                 if ((tun->flags & TUN_TYPE_MASK) != IFF_TAP)
2127                         break;
2128                 ret = update_filter(&tun->txflt, (void __user *)arg);
2129                 break;
2130 
2131         case SIOCGIFHWADDR:
2132                 /* Get hw address */
2133                 memcpy(ifr.ifr_hwaddr.sa_data, tun->dev->dev_addr, ETH_ALEN);
2134                 ifr.ifr_hwaddr.sa_family = tun->dev->type;
2135                 if (copy_to_user(argp, &ifr, ifreq_len))
2136                         ret = -EFAULT;
2137                 break;
2138 
2139         case SIOCSIFHWADDR:
2140                 /* Set hw address */
2141                 tun_debug(KERN_DEBUG, tun, "set hw address: %pM\n",
2142                           ifr.ifr_hwaddr.sa_data);
2143 
2144                 ret = dev_set_mac_address(tun->dev, &ifr.ifr_hwaddr);
2145                 break;
2146 
2147         case TUNGETSNDBUF:
2148                 sndbuf = tfile->socket.sk->sk_sndbuf;
2149                 if (copy_to_user(argp, &sndbuf, sizeof(sndbuf)))
2150                         ret = -EFAULT;
2151                 break;
2152 
2153         case TUNSETSNDBUF:
2154                 if (copy_from_user(&sndbuf, argp, sizeof(sndbuf))) {
2155                         ret = -EFAULT;
2156                         break;
2157                 }
2158 
2159                 tun->sndbuf = sndbuf;
2160                 tun_set_sndbuf(tun);
2161                 break;
2162 
2163         case TUNGETVNETHDRSZ:
2164                 vnet_hdr_sz = tun->vnet_hdr_sz;
2165                 if (copy_to_user(argp, &vnet_hdr_sz, sizeof(vnet_hdr_sz)))
2166                         ret = -EFAULT;
2167                 break;
2168 
2169         case TUNSETVNETHDRSZ:
2170                 if (copy_from_user(&vnet_hdr_sz, argp, sizeof(vnet_hdr_sz))) {
2171                         ret = -EFAULT;
2172                         break;
2173                 }
2174                 if (vnet_hdr_sz < (int)sizeof(struct virtio_net_hdr)) {
2175                         ret = -EINVAL;
2176                         break;
2177                 }
2178 
2179                 tun->vnet_hdr_sz = vnet_hdr_sz;
2180                 break;
2181 
2182         case TUNGETVNETLE:
2183                 le = !!(tun->flags & TUN_VNET_LE);
2184                 if (put_user(le, (int __user *)argp))
2185                         ret = -EFAULT;
2186                 break;
2187 
2188         case TUNSETVNETLE:
2189                 if (get_user(le, (int __user *)argp)) {
2190                         ret = -EFAULT;
2191                         break;
2192                 }
2193                 if (le)
2194                         tun->flags |= TUN_VNET_LE;
2195                 else
2196                         tun->flags &= ~TUN_VNET_LE;
2197                 break;
2198 
2199         case TUNGETVNETBE:
2200                 ret = tun_get_vnet_be(tun, argp);
2201                 break;
2202 
2203         case TUNSETVNETBE:
2204                 ret = tun_set_vnet_be(tun, argp);
2205                 break;
2206 
2207         case TUNATTACHFILTER:
2208                 /* Can be set only for TAPs */
2209                 ret = -EINVAL;
2210                 if ((tun->flags & TUN_TYPE_MASK) != IFF_TAP)
2211                         break;
2212                 ret = -EFAULT;
2213                 if (copy_from_user(&tun->fprog, argp, sizeof(tun->fprog)))
2214                         break;
2215 
2216                 ret = tun_attach_filter(tun);
2217                 break;
2218 
2219         case TUNDETACHFILTER:
2220                 /* Can be set only for TAPs */
2221                 ret = -EINVAL;
2222                 if ((tun->flags & TUN_TYPE_MASK) != IFF_TAP)
2223                         break;
2224                 ret = 0;
2225                 tun_detach_filter(tun, tun->numqueues);
2226                 break;
2227 
2228         case TUNGETFILTER:
2229                 ret = -EINVAL;
2230                 if ((tun->flags & TUN_TYPE_MASK) != IFF_TAP)
2231                         break;
2232                 ret = -EFAULT;
2233                 if (copy_to_user(argp, &tun->fprog, sizeof(tun->fprog)))
2234                         break;
2235                 ret = 0;
2236                 break;
2237 
2238         default:
2239                 ret = -EINVAL;
2240                 break;
2241         }
2242 
2243 unlock:
2244         rtnl_unlock();
2245         if (tun)
2246                 tun_put(tun);
2247         return ret;
2248 }
2249 
2250 static long tun_chr_ioctl(struct file *file,
2251                           unsigned int cmd, unsigned long arg)
2252 {
2253         return __tun_chr_ioctl(file, cmd, arg, sizeof (struct ifreq));
2254 }
2255 
2256 #ifdef CONFIG_COMPAT
2257 static long tun_chr_compat_ioctl(struct file *file,
2258                          unsigned int cmd, unsigned long arg)
2259 {
2260         switch (cmd) {
2261         case TUNSETIFF:
2262         case TUNGETIFF:
2263         case TUNSETTXFILTER:
2264         case TUNGETSNDBUF:
2265         case TUNSETSNDBUF:
2266         case SIOCGIFHWADDR:
2267         case SIOCSIFHWADDR:
2268                 arg = (unsigned long)compat_ptr(arg);
2269                 break;
2270         default:
2271                 arg = (compat_ulong_t)arg;
2272                 break;
2273         }
2274 
2275         /*
2276          * compat_ifreq is shorter than ifreq, so we must not access beyond
2277          * the end of that structure. All fields that are used in this
2278          * driver are compatible though, we don't need to convert the
2279          * contents.
2280          */
2281         return __tun_chr_ioctl(file, cmd, arg, sizeof(struct compat_ifreq));
2282 }
2283 #endif /* CONFIG_COMPAT */
2284 
2285 static int tun_chr_fasync(int fd, struct file *file, int on)
2286 {
2287         struct tun_file *tfile = file->private_data;
2288         int ret;
2289 
2290         if ((ret = fasync_helper(fd, file, on, &tfile->fasync)) < 0)
2291                 goto out;
2292 
2293         if (on) {
2294                 __f_setown(file, task_pid(current), PIDTYPE_PID, 0);
2295                 tfile->flags |= TUN_FASYNC;
2296         } else
2297                 tfile->flags &= ~TUN_FASYNC;
2298         ret = 0;
2299 out:
2300         return ret;
2301 }
2302 
2303 static int tun_chr_open(struct inode *inode, struct file * file)
2304 {
2305         struct net *net = current->nsproxy->net_ns;
2306         struct tun_file *tfile;
2307 
2308         DBG1(KERN_INFO, "tunX: tun_chr_open\n");
2309 
2310         tfile = (struct tun_file *)sk_alloc(net, AF_UNSPEC, GFP_KERNEL,
2311                                             &tun_proto, 0);
2312         if (!tfile)
2313                 return -ENOMEM;
2314         RCU_INIT_POINTER(tfile->tun, NULL);
2315         tfile->flags = 0;
2316         tfile->ifindex = 0;
2317 
2318         init_waitqueue_head(&tfile->wq.wait);
2319         RCU_INIT_POINTER(tfile->socket.wq, &tfile->wq);
2320 
2321         tfile->socket.file = file;
2322         tfile->socket.ops = &tun_socket_ops;
2323 
2324         sock_init_data(&tfile->socket, &tfile->sk);
2325 
2326         tfile->sk.sk_write_space = tun_sock_write_space;
2327         tfile->sk.sk_sndbuf = INT_MAX;
2328 
2329         file->private_data = tfile;
2330         INIT_LIST_HEAD(&tfile->next);
2331 
2332         sock_set_flag(&tfile->sk, SOCK_ZEROCOPY);
2333 
2334         return 0;
2335 }
2336 
2337 static int tun_chr_close(struct inode *inode, struct file *file)
2338 {
2339         struct tun_file *tfile = file->private_data;
2340 
2341         tun_detach(tfile, true);
2342 
2343         return 0;
2344 }
2345 
2346 #ifdef CONFIG_PROC_FS
2347 static void tun_chr_show_fdinfo(struct seq_file *m, struct file *f)
2348 {
2349         struct tun_struct *tun;
2350         struct ifreq ifr;
2351 
2352         memset(&ifr, 0, sizeof(ifr));
2353 
2354         rtnl_lock();
2355         tun = tun_get(f);
2356         if (tun)
2357                 tun_get_iff(current->nsproxy->net_ns, tun, &ifr);
2358         rtnl_unlock();
2359 
2360         if (tun)
2361                 tun_put(tun);
2362 
2363         seq_printf(m, "iff:\t%s\n", ifr.ifr_name);
2364 }
2365 #endif
2366 
2367 static const struct file_operations tun_fops = {
2368         .owner  = THIS_MODULE,
2369         .llseek = no_llseek,
2370         .read_iter  = tun_chr_read_iter,
2371         .write_iter = tun_chr_write_iter,
2372         .poll   = tun_chr_poll,
2373         .unlocked_ioctl = tun_chr_ioctl,
2374 #ifdef CONFIG_COMPAT
2375         .compat_ioctl = tun_chr_compat_ioctl,
2376 #endif
2377         .open   = tun_chr_open,
2378         .release = tun_chr_close,
2379         .fasync = tun_chr_fasync,
2380 #ifdef CONFIG_PROC_FS
2381         .show_fdinfo = tun_chr_show_fdinfo,
2382 #endif
2383 };
2384 
2385 static struct miscdevice tun_miscdev = {
2386         .minor = TUN_MINOR,
2387         .name = "tun",
2388         .nodename = "net/tun",
2389         .fops = &tun_fops,
2390 };
2391 
2392 /* ethtool interface */
2393 
2394 static int tun_get_settings(struct net_device *dev, struct ethtool_cmd *cmd)
2395 {
2396         cmd->supported          = 0;
2397         cmd->advertising        = 0;
2398         ethtool_cmd_speed_set(cmd, SPEED_10);
2399         cmd->duplex             = DUPLEX_FULL;
2400         cmd->port               = PORT_TP;
2401         cmd->phy_address        = 0;
2402         cmd->transceiver        = XCVR_INTERNAL;
2403         cmd->autoneg            = AUTONEG_DISABLE;
2404         cmd->maxtxpkt           = 0;
2405         cmd->maxrxpkt           = 0;
2406         return 0;
2407 }
2408 
2409 static void tun_get_drvinfo(struct net_device *dev, struct ethtool_drvinfo *info)
2410 {
2411         struct tun_struct *tun = netdev_priv(dev);
2412 
2413         strlcpy(info->driver, DRV_NAME, sizeof(info->driver));
2414         strlcpy(info->version, DRV_VERSION, sizeof(info->version));
2415 
2416         switch (tun->flags & TUN_TYPE_MASK) {
2417         case IFF_TUN:
2418                 strlcpy(info->bus_info, "tun", sizeof(info->bus_info));
2419                 break;
2420         case IFF_TAP:
2421                 strlcpy(info->bus_info, "tap", sizeof(info->bus_info));
2422                 break;
2423         }
2424 }
2425 
2426 static u32 tun_get_msglevel(struct net_device *dev)
2427 {
2428 #ifdef TUN_DEBUG
2429         struct tun_struct *tun = netdev_priv(dev);
2430         return tun->debug;
2431 #else
2432         return -EOPNOTSUPP;
2433 #endif
2434 }
2435 
2436 static void tun_set_msglevel(struct net_device *dev, u32 value)
2437 {
2438 #ifdef TUN_DEBUG
2439         struct tun_struct *tun = netdev_priv(dev);
2440         tun->debug = value;
2441 #endif
2442 }
2443 
2444 static const struct ethtool_ops tun_ethtool_ops = {
2445         .get_settings   = tun_get_settings,
2446         .get_drvinfo    = tun_get_drvinfo,
2447         .get_msglevel   = tun_get_msglevel,
2448         .set_msglevel   = tun_set_msglevel,
2449         .get_link       = ethtool_op_get_link,
2450         .get_ts_info    = ethtool_op_get_ts_info,
2451 };
2452 
2453 static int tun_queue_resize(struct tun_struct *tun)
2454 {
2455         struct net_device *dev = tun->dev;
2456         struct tun_file *tfile;
2457         struct skb_array **arrays;
2458         int n = tun->numqueues + tun->numdisabled;
2459         int ret, i;
2460 
2461         arrays = kmalloc(sizeof *arrays * n, GFP_KERNEL);
2462         if (!arrays)
2463                 return -ENOMEM;
2464 
2465         for (i = 0; i < tun->numqueues; i++) {
2466                 tfile = rtnl_dereference(tun->tfiles[i]);
2467                 arrays[i] = &tfile->tx_array;
2468         }
2469         list_for_each_entry(tfile, &tun->disabled, next)
2470                 arrays[i++] = &tfile->tx_array;
2471 
2472         ret = skb_array_resize_multiple(arrays, n,
2473                                         dev->tx_queue_len, GFP_KERNEL);
2474 
2475         kfree(arrays);
2476         return ret;
2477 }
2478 
2479 static int tun_device_event(struct notifier_block *unused,
2480                             unsigned long event, void *ptr)
2481 {
2482         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
2483         struct tun_struct *tun = netdev_priv(dev);
2484 
2485         if (dev->rtnl_link_ops != &tun_link_ops)
2486                 return NOTIFY_DONE;
2487 
2488         switch (event) {
2489         case NETDEV_CHANGE_TX_QUEUE_LEN:
2490                 if (tun_queue_resize(tun))
2491                         return NOTIFY_BAD;
2492                 break;
2493         default:
2494                 break;
2495         }
2496 
2497         return NOTIFY_DONE;
2498 }
2499 
2500 static struct notifier_block tun_notifier_block __read_mostly = {
2501         .notifier_call  = tun_device_event,
2502 };
2503 
2504 static int __init tun_init(void)
2505 {
2506         int ret = 0;
2507 
2508         pr_info("%s, %s\n", DRV_DESCRIPTION, DRV_VERSION);
2509         pr_info("%s\n", DRV_COPYRIGHT);
2510 
2511         ret = rtnl_link_register(&tun_link_ops);
2512         if (ret) {
2513                 pr_err("Can't register link_ops\n");
2514                 goto err_linkops;
2515         }
2516 
2517         ret = misc_register(&tun_miscdev);
2518         if (ret) {
2519                 pr_err("Can't register misc device %d\n", TUN_MINOR);
2520                 goto err_misc;
2521         }
2522 
2523         register_netdevice_notifier(&tun_notifier_block);
2524         return  0;
2525 err_misc:
2526         rtnl_link_unregister(&tun_link_ops);
2527 err_linkops:
2528         return ret;
2529 }
2530 
2531 static void tun_cleanup(void)
2532 {
2533         misc_deregister(&tun_miscdev);
2534         rtnl_link_unregister(&tun_link_ops);
2535         unregister_netdevice_notifier(&tun_notifier_block);
2536 }
2537 
2538 /* Get an underlying socket object from tun file.  Returns error unless file is
2539  * attached to a device.  The returned object works like a packet socket, it
2540  * can be used for sock_sendmsg/sock_recvmsg.  The caller is responsible for
2541  * holding a reference to the file for as long as the socket is in use. */
2542 struct socket *tun_get_socket(struct file *file)
2543 {
2544         struct tun_file *tfile;
2545         if (file->f_op != &tun_fops)
2546                 return ERR_PTR(-EINVAL);
2547         tfile = file->private_data;
2548         if (!tfile)
2549                 return ERR_PTR(-EBADFD);
2550         return &tfile->socket;
2551 }
2552 EXPORT_SYMBOL_GPL(tun_get_socket);
2553 
2554 module_init(tun_init);
2555 module_exit(tun_cleanup);
2556 MODULE_DESCRIPTION(DRV_DESCRIPTION);
2557 MODULE_AUTHOR(DRV_COPYRIGHT);
2558 MODULE_LICENSE("GPL");
2559 MODULE_ALIAS_MISCDEV(TUN_MINOR);
2560 MODULE_ALIAS("devname:net/tun");
2561 

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