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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/ipv6.h>
 69 #include <net/net_namespace.h>
 70 #include <net/netns/generic.h>
 71 #include <net/rtnetlink.h>
 72 #include <net/sock.h>
 73 #include <linux/seq_file.h>
 74 
 75 #include <asm/uaccess.h>
 76 
 77 /* Uncomment to enable debugging */
 78 /* #define TUN_DEBUG 1 */
 79 
 80 #ifdef TUN_DEBUG
 81 static int debug;
 82 
 83 #define tun_debug(level, tun, fmt, args...)                     \
 84 do {                                                            \
 85         if (tun->debug)                                         \
 86                 netdev_printk(level, tun->dev, fmt, ##args);    \
 87 } while (0)
 88 #define DBG1(level, fmt, args...)                               \
 89 do {                                                            \
 90         if (debug == 2)                                         \
 91                 printk(level fmt, ##args);                      \
 92 } while (0)
 93 #else
 94 #define tun_debug(level, tun, fmt, args...)                     \
 95 do {                                                            \
 96         if (0)                                                  \
 97                 netdev_printk(level, tun->dev, fmt, ##args);    \
 98 } while (0)
 99 #define DBG1(level, fmt, args...)                               \
100 do {                                                            \
101         if (0)                                                  \
102                 printk(level fmt, ##args);                      \
103 } while (0)
104 #endif
105 
106 #define GOODCOPY_LEN 128
107 
108 #define FLT_EXACT_COUNT 8
109 struct tap_filter {
110         unsigned int    count;    /* Number of addrs. Zero means disabled */
111         u32             mask[2];  /* Mask of the hashed addrs */
112         unsigned char   addr[FLT_EXACT_COUNT][ETH_ALEN];
113 };
114 
115 /* DEFAULT_MAX_NUM_RSS_QUEUES were chosen to let the rx/tx queues allocated for
116  * the netdevice to be fit in one page. So we can make sure the success of
117  * memory allocation. TODO: increase the limit. */
118 #define MAX_TAP_QUEUES DEFAULT_MAX_NUM_RSS_QUEUES
119 #define MAX_TAP_FLOWS  4096
120 
121 #define TUN_FLOW_EXPIRE (3 * HZ)
122 
123 /* A tun_file connects an open character device to a tuntap netdevice. It
124  * also contains all socket related structures (except sock_fprog and tap_filter)
125  * to serve as one transmit queue for tuntap device. The sock_fprog and
126  * tap_filter were kept in tun_struct since they were used for filtering for the
127  * netdevice not for a specific queue (at least I didn't see the requirement for
128  * this).
129  *
130  * RCU usage:
131  * The tun_file and tun_struct are loosely coupled, the pointer from one to the
132  * other can only be read while rcu_read_lock or rtnl_lock is held.
133  */
134 struct tun_file {
135         struct sock sk;
136         struct socket socket;
137         struct socket_wq wq;
138         struct tun_struct __rcu *tun;
139         struct net *net;
140         struct fasync_struct *fasync;
141         /* only used for fasnyc */
142         unsigned int flags;
143         union {
144                 u16 queue_index;
145                 unsigned int ifindex;
146         };
147         struct list_head next;
148         struct tun_struct *detached;
149 };
150 
151 struct tun_flow_entry {
152         struct hlist_node hash_link;
153         struct rcu_head rcu;
154         struct tun_struct *tun;
155 
156         u32 rxhash;
157         u32 rps_rxhash;
158         int queue_index;
159         unsigned long updated;
160 };
161 
162 #define TUN_NUM_FLOW_ENTRIES 1024
163 
164 /* Since the socket were moved to tun_file, to preserve the behavior of persist
165  * device, socket filter, sndbuf and vnet header size were restore when the
166  * file were attached to a persist device.
167  */
168 struct tun_struct {
169         struct tun_file __rcu   *tfiles[MAX_TAP_QUEUES];
170         unsigned int            numqueues;
171         unsigned int            flags;
172         kuid_t                  owner;
173         kgid_t                  group;
174 
175         struct net_device       *dev;
176         netdev_features_t       set_features;
177 #define TUN_USER_FEATURES (NETIF_F_HW_CSUM|NETIF_F_TSO_ECN|NETIF_F_TSO| \
178                           NETIF_F_TSO6)
179 
180         int                     vnet_hdr_sz;
181         int                     sndbuf;
182         struct tap_filter       txflt;
183         struct sock_fprog       fprog;
184         /* protected by rtnl lock */
185         bool                    filter_attached;
186 #ifdef TUN_DEBUG
187         int debug;
188 #endif
189         spinlock_t lock;
190         struct hlist_head flows[TUN_NUM_FLOW_ENTRIES];
191         struct timer_list flow_gc_timer;
192         unsigned long ageing_time;
193         unsigned int numdisabled;
194         struct list_head disabled;
195         void *security;
196         u32 flow_count;
197 };
198 
199 static inline u32 tun_hashfn(u32 rxhash)
200 {
201         return rxhash & 0x3ff;
202 }
203 
204 static struct tun_flow_entry *tun_flow_find(struct hlist_head *head, u32 rxhash)
205 {
206         struct tun_flow_entry *e;
207 
208         hlist_for_each_entry_rcu(e, head, hash_link) {
209                 if (e->rxhash == rxhash)
210                         return e;
211         }
212         return NULL;
213 }
214 
215 static struct tun_flow_entry *tun_flow_create(struct tun_struct *tun,
216                                               struct hlist_head *head,
217                                               u32 rxhash, u16 queue_index)
218 {
219         struct tun_flow_entry *e = kmalloc(sizeof(*e), GFP_ATOMIC);
220 
221         if (e) {
222                 tun_debug(KERN_INFO, tun, "create flow: hash %u index %u\n",
223                           rxhash, queue_index);
224                 e->updated = jiffies;
225                 e->rxhash = rxhash;
226                 e->rps_rxhash = 0;
227                 e->queue_index = queue_index;
228                 e->tun = tun;
229                 hlist_add_head_rcu(&e->hash_link, head);
230                 ++tun->flow_count;
231         }
232         return e;
233 }
234 
235 static void tun_flow_delete(struct tun_struct *tun, struct tun_flow_entry *e)
236 {
237         tun_debug(KERN_INFO, tun, "delete flow: hash %u index %u\n",
238                   e->rxhash, e->queue_index);
239         sock_rps_reset_flow_hash(e->rps_rxhash);
240         hlist_del_rcu(&e->hash_link);
241         kfree_rcu(e, rcu);
242         --tun->flow_count;
243 }
244 
245 static void tun_flow_flush(struct tun_struct *tun)
246 {
247         int i;
248 
249         spin_lock_bh(&tun->lock);
250         for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) {
251                 struct tun_flow_entry *e;
252                 struct hlist_node *n;
253 
254                 hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link)
255                         tun_flow_delete(tun, e);
256         }
257         spin_unlock_bh(&tun->lock);
258 }
259 
260 static void tun_flow_delete_by_queue(struct tun_struct *tun, u16 queue_index)
261 {
262         int i;
263 
264         spin_lock_bh(&tun->lock);
265         for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) {
266                 struct tun_flow_entry *e;
267                 struct hlist_node *n;
268 
269                 hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link) {
270                         if (e->queue_index == queue_index)
271                                 tun_flow_delete(tun, e);
272                 }
273         }
274         spin_unlock_bh(&tun->lock);
275 }
276 
277 static void tun_flow_cleanup(unsigned long data)
278 {
279         struct tun_struct *tun = (struct tun_struct *)data;
280         unsigned long delay = tun->ageing_time;
281         unsigned long next_timer = jiffies + delay;
282         unsigned long count = 0;
283         int i;
284 
285         tun_debug(KERN_INFO, tun, "tun_flow_cleanup\n");
286 
287         spin_lock_bh(&tun->lock);
288         for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) {
289                 struct tun_flow_entry *e;
290                 struct hlist_node *n;
291 
292                 hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link) {
293                         unsigned long this_timer;
294                         count++;
295                         this_timer = e->updated + delay;
296                         if (time_before_eq(this_timer, jiffies))
297                                 tun_flow_delete(tun, e);
298                         else if (time_before(this_timer, next_timer))
299                                 next_timer = this_timer;
300                 }
301         }
302 
303         if (count)
304                 mod_timer(&tun->flow_gc_timer, round_jiffies_up(next_timer));
305         spin_unlock_bh(&tun->lock);
306 }
307 
308 static void tun_flow_update(struct tun_struct *tun, u32 rxhash,
309                             struct tun_file *tfile)
310 {
311         struct hlist_head *head;
312         struct tun_flow_entry *e;
313         unsigned long delay = tun->ageing_time;
314         u16 queue_index = tfile->queue_index;
315 
316         if (!rxhash)
317                 return;
318         else
319                 head = &tun->flows[tun_hashfn(rxhash)];
320 
321         rcu_read_lock();
322 
323         /* We may get a very small possibility of OOO during switching, not
324          * worth to optimize.*/
325         if (tun->numqueues == 1 || tfile->detached)
326                 goto unlock;
327 
328         e = tun_flow_find(head, rxhash);
329         if (likely(e)) {
330                 /* TODO: keep queueing to old queue until it's empty? */
331                 e->queue_index = queue_index;
332                 e->updated = jiffies;
333                 sock_rps_record_flow_hash(e->rps_rxhash);
334         } else {
335                 spin_lock_bh(&tun->lock);
336                 if (!tun_flow_find(head, rxhash) &&
337                     tun->flow_count < MAX_TAP_FLOWS)
338                         tun_flow_create(tun, head, rxhash, queue_index);
339 
340                 if (!timer_pending(&tun->flow_gc_timer))
341                         mod_timer(&tun->flow_gc_timer,
342                                   round_jiffies_up(jiffies + delay));
343                 spin_unlock_bh(&tun->lock);
344         }
345 
346 unlock:
347         rcu_read_unlock();
348 }
349 
350 /**
351  * Save the hash received in the stack receive path and update the
352  * flow_hash table accordingly.
353  */
354 static inline void tun_flow_save_rps_rxhash(struct tun_flow_entry *e, u32 hash)
355 {
356         if (unlikely(e->rps_rxhash != hash)) {
357                 sock_rps_reset_flow_hash(e->rps_rxhash);
358                 e->rps_rxhash = hash;
359         }
360 }
361 
362 /* We try to identify a flow through its rxhash first. The reason that
363  * we do not check rxq no. is because some cards(e.g 82599), chooses
364  * the rxq based on the txq where the last packet of the flow comes. As
365  * the userspace application move between processors, we may get a
366  * different rxq no. here. If we could not get rxhash, then we would
367  * hope the rxq no. may help here.
368  */
369 static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb,
370                             void *accel_priv, select_queue_fallback_t fallback)
371 {
372         struct tun_struct *tun = netdev_priv(dev);
373         struct tun_flow_entry *e;
374         u32 txq = 0;
375         u32 numqueues = 0;
376 
377         rcu_read_lock();
378         numqueues = ACCESS_ONCE(tun->numqueues);
379 
380         txq = skb_get_hash(skb);
381         if (txq) {
382                 e = tun_flow_find(&tun->flows[tun_hashfn(txq)], txq);
383                 if (e) {
384                         tun_flow_save_rps_rxhash(e, txq);
385                         txq = e->queue_index;
386                 } else
387                         /* use multiply and shift instead of expensive divide */
388                         txq = ((u64)txq * numqueues) >> 32;
389         } else if (likely(skb_rx_queue_recorded(skb))) {
390                 txq = skb_get_rx_queue(skb);
391                 while (unlikely(txq >= numqueues))
392                         txq -= numqueues;
393         }
394 
395         rcu_read_unlock();
396         return txq;
397 }
398 
399 static inline bool tun_not_capable(struct tun_struct *tun)
400 {
401         const struct cred *cred = current_cred();
402         struct net *net = dev_net(tun->dev);
403 
404         return ((uid_valid(tun->owner) && !uid_eq(cred->euid, tun->owner)) ||
405                   (gid_valid(tun->group) && !in_egroup_p(tun->group))) &&
406                 !ns_capable(net->user_ns, CAP_NET_ADMIN);
407 }
408 
409 static void tun_set_real_num_queues(struct tun_struct *tun)
410 {
411         netif_set_real_num_tx_queues(tun->dev, tun->numqueues);
412         netif_set_real_num_rx_queues(tun->dev, tun->numqueues);
413 }
414 
415 static void tun_disable_queue(struct tun_struct *tun, struct tun_file *tfile)
416 {
417         tfile->detached = tun;
418         list_add_tail(&tfile->next, &tun->disabled);
419         ++tun->numdisabled;
420 }
421 
422 static struct tun_struct *tun_enable_queue(struct tun_file *tfile)
423 {
424         struct tun_struct *tun = tfile->detached;
425 
426         tfile->detached = NULL;
427         list_del_init(&tfile->next);
428         --tun->numdisabled;
429         return tun;
430 }
431 
432 static void tun_queue_purge(struct tun_file *tfile)
433 {
434         skb_queue_purge(&tfile->sk.sk_receive_queue);
435         skb_queue_purge(&tfile->sk.sk_error_queue);
436 }
437 
438 static void __tun_detach(struct tun_file *tfile, bool clean)
439 {
440         struct tun_file *ntfile;
441         struct tun_struct *tun;
442 
443         tun = rtnl_dereference(tfile->tun);
444 
445         if (tun && !tfile->detached) {
446                 u16 index = tfile->queue_index;
447                 BUG_ON(index >= tun->numqueues);
448 
449                 rcu_assign_pointer(tun->tfiles[index],
450                                    tun->tfiles[tun->numqueues - 1]);
451                 ntfile = rtnl_dereference(tun->tfiles[index]);
452                 ntfile->queue_index = index;
453 
454                 --tun->numqueues;
455                 if (clean) {
456                         RCU_INIT_POINTER(tfile->tun, NULL);
457                         sock_put(&tfile->sk);
458                 } else
459                         tun_disable_queue(tun, tfile);
460 
461                 synchronize_net();
462                 tun_flow_delete_by_queue(tun, tun->numqueues + 1);
463                 /* Drop read queue */
464                 tun_queue_purge(tfile);
465                 tun_set_real_num_queues(tun);
466         } else if (tfile->detached && clean) {
467                 tun = tun_enable_queue(tfile);
468                 sock_put(&tfile->sk);
469         }
470 
471         if (clean) {
472                 if (tun && tun->numqueues == 0 && tun->numdisabled == 0) {
473                         netif_carrier_off(tun->dev);
474 
475                         if (!(tun->flags & TUN_PERSIST) &&
476                             tun->dev->reg_state == NETREG_REGISTERED)
477                                 unregister_netdevice(tun->dev);
478                 }
479 
480                 BUG_ON(!test_bit(SOCK_EXTERNALLY_ALLOCATED,
481                                  &tfile->socket.flags));
482                 sk_release_kernel(&tfile->sk);
483         }
484 }
485 
486 static void tun_detach(struct tun_file *tfile, bool clean)
487 {
488         rtnl_lock();
489         __tun_detach(tfile, clean);
490         rtnl_unlock();
491 }
492 
493 static void tun_detach_all(struct net_device *dev)
494 {
495         struct tun_struct *tun = netdev_priv(dev);
496         struct tun_file *tfile, *tmp;
497         int i, n = tun->numqueues;
498 
499         for (i = 0; i < n; i++) {
500                 tfile = rtnl_dereference(tun->tfiles[i]);
501                 BUG_ON(!tfile);
502                 tfile->socket.sk->sk_data_ready(tfile->socket.sk);
503                 RCU_INIT_POINTER(tfile->tun, NULL);
504                 --tun->numqueues;
505         }
506         list_for_each_entry(tfile, &tun->disabled, next) {
507                 tfile->socket.sk->sk_data_ready(tfile->socket.sk);
508                 RCU_INIT_POINTER(tfile->tun, NULL);
509         }
510         BUG_ON(tun->numqueues != 0);
511 
512         synchronize_net();
513         for (i = 0; i < n; i++) {
514                 tfile = rtnl_dereference(tun->tfiles[i]);
515                 /* Drop read queue */
516                 tun_queue_purge(tfile);
517                 sock_put(&tfile->sk);
518         }
519         list_for_each_entry_safe(tfile, tmp, &tun->disabled, next) {
520                 tun_enable_queue(tfile);
521                 tun_queue_purge(tfile);
522                 sock_put(&tfile->sk);
523         }
524         BUG_ON(tun->numdisabled != 0);
525 
526         if (tun->flags & TUN_PERSIST)
527                 module_put(THIS_MODULE);
528 }
529 
530 static int tun_attach(struct tun_struct *tun, struct file *file, bool skip_filter)
531 {
532         struct tun_file *tfile = file->private_data;
533         int err;
534 
535         err = security_tun_dev_attach(tfile->socket.sk, tun->security);
536         if (err < 0)
537                 goto out;
538 
539         err = -EINVAL;
540         if (rtnl_dereference(tfile->tun) && !tfile->detached)
541                 goto out;
542 
543         err = -EBUSY;
544         if (!(tun->flags & TUN_TAP_MQ) && tun->numqueues == 1)
545                 goto out;
546 
547         err = -E2BIG;
548         if (!tfile->detached &&
549             tun->numqueues + tun->numdisabled == MAX_TAP_QUEUES)
550                 goto out;
551 
552         err = 0;
553 
554         /* Re-attach the filter to persist device */
555         if (!skip_filter && (tun->filter_attached == true)) {
556                 err = sk_attach_filter(&tun->fprog, tfile->socket.sk);
557                 if (!err)
558                         goto out;
559         }
560         tfile->queue_index = tun->numqueues;
561         rcu_assign_pointer(tfile->tun, tun);
562         rcu_assign_pointer(tun->tfiles[tun->numqueues], tfile);
563         tun->numqueues++;
564 
565         if (tfile->detached)
566                 tun_enable_queue(tfile);
567         else
568                 sock_hold(&tfile->sk);
569 
570         tun_set_real_num_queues(tun);
571 
572         /* device is allowed to go away first, so no need to hold extra
573          * refcnt.
574          */
575 
576 out:
577         return err;
578 }
579 
580 static struct tun_struct *__tun_get(struct tun_file *tfile)
581 {
582         struct tun_struct *tun;
583 
584         rcu_read_lock();
585         tun = rcu_dereference(tfile->tun);
586         if (tun)
587                 dev_hold(tun->dev);
588         rcu_read_unlock();
589 
590         return tun;
591 }
592 
593 static struct tun_struct *tun_get(struct file *file)
594 {
595         return __tun_get(file->private_data);
596 }
597 
598 static void tun_put(struct tun_struct *tun)
599 {
600         dev_put(tun->dev);
601 }
602 
603 /* TAP filtering */
604 static void addr_hash_set(u32 *mask, const u8 *addr)
605 {
606         int n = ether_crc(ETH_ALEN, addr) >> 26;
607         mask[n >> 5] |= (1 << (n & 31));
608 }
609 
610 static unsigned int addr_hash_test(const u32 *mask, const u8 *addr)
611 {
612         int n = ether_crc(ETH_ALEN, addr) >> 26;
613         return mask[n >> 5] & (1 << (n & 31));
614 }
615 
616 static int update_filter(struct tap_filter *filter, void __user *arg)
617 {
618         struct { u8 u[ETH_ALEN]; } *addr;
619         struct tun_filter uf;
620         int err, alen, n, nexact;
621 
622         if (copy_from_user(&uf, arg, sizeof(uf)))
623                 return -EFAULT;
624 
625         if (!uf.count) {
626                 /* Disabled */
627                 filter->count = 0;
628                 return 0;
629         }
630 
631         alen = ETH_ALEN * uf.count;
632         addr = kmalloc(alen, GFP_KERNEL);
633         if (!addr)
634                 return -ENOMEM;
635 
636         if (copy_from_user(addr, arg + sizeof(uf), alen)) {
637                 err = -EFAULT;
638                 goto done;
639         }
640 
641         /* The filter is updated without holding any locks. Which is
642          * perfectly safe. We disable it first and in the worst
643          * case we'll accept a few undesired packets. */
644         filter->count = 0;
645         wmb();
646 
647         /* Use first set of addresses as an exact filter */
648         for (n = 0; n < uf.count && n < FLT_EXACT_COUNT; n++)
649                 memcpy(filter->addr[n], addr[n].u, ETH_ALEN);
650 
651         nexact = n;
652 
653         /* Remaining multicast addresses are hashed,
654          * unicast will leave the filter disabled. */
655         memset(filter->mask, 0, sizeof(filter->mask));
656         for (; n < uf.count; n++) {
657                 if (!is_multicast_ether_addr(addr[n].u)) {
658                         err = 0; /* no filter */
659                         goto done;
660                 }
661                 addr_hash_set(filter->mask, addr[n].u);
662         }
663 
664         /* For ALLMULTI just set the mask to all ones.
665          * This overrides the mask populated above. */
666         if ((uf.flags & TUN_FLT_ALLMULTI))
667                 memset(filter->mask, ~0, sizeof(filter->mask));
668 
669         /* Now enable the filter */
670         wmb();
671         filter->count = nexact;
672 
673         /* Return the number of exact filters */
674         err = nexact;
675 
676 done:
677         kfree(addr);
678         return err;
679 }
680 
681 /* Returns: 0 - drop, !=0 - accept */
682 static int run_filter(struct tap_filter *filter, const struct sk_buff *skb)
683 {
684         /* Cannot use eth_hdr(skb) here because skb_mac_hdr() is incorrect
685          * at this point. */
686         struct ethhdr *eh = (struct ethhdr *) skb->data;
687         int i;
688 
689         /* Exact match */
690         for (i = 0; i < filter->count; i++)
691                 if (ether_addr_equal(eh->h_dest, filter->addr[i]))
692                         return 1;
693 
694         /* Inexact match (multicast only) */
695         if (is_multicast_ether_addr(eh->h_dest))
696                 return addr_hash_test(filter->mask, eh->h_dest);
697 
698         return 0;
699 }
700 
701 /*
702  * Checks whether the packet is accepted or not.
703  * Returns: 0 - drop, !=0 - accept
704  */
705 static int check_filter(struct tap_filter *filter, const struct sk_buff *skb)
706 {
707         if (!filter->count)
708                 return 1;
709 
710         return run_filter(filter, skb);
711 }
712 
713 /* Network device part of the driver */
714 
715 static const struct ethtool_ops tun_ethtool_ops;
716 
717 /* Net device detach from fd. */
718 static void tun_net_uninit(struct net_device *dev)
719 {
720         tun_detach_all(dev);
721 }
722 
723 /* Net device open. */
724 static int tun_net_open(struct net_device *dev)
725 {
726         netif_tx_start_all_queues(dev);
727         return 0;
728 }
729 
730 /* Net device close. */
731 static int tun_net_close(struct net_device *dev)
732 {
733         netif_tx_stop_all_queues(dev);
734         return 0;
735 }
736 
737 /* Net device start xmit */
738 static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
739 {
740         struct tun_struct *tun = netdev_priv(dev);
741         int txq = skb->queue_mapping;
742         struct tun_file *tfile;
743         u32 numqueues = 0;
744 
745         rcu_read_lock();
746         tfile = rcu_dereference(tun->tfiles[txq]);
747         numqueues = ACCESS_ONCE(tun->numqueues);
748 
749         /* Drop packet if interface is not attached */
750         if (txq >= numqueues)
751                 goto drop;
752 
753         if (numqueues == 1) {
754                 /* Select queue was not called for the skbuff, so we extract the
755                  * RPS hash and save it into the flow_table here.
756                  */
757                 __u32 rxhash;
758 
759                 rxhash = skb_get_hash(skb);
760                 if (rxhash) {
761                         struct tun_flow_entry *e;
762                         e = tun_flow_find(&tun->flows[tun_hashfn(rxhash)],
763                                         rxhash);
764                         if (e)
765                                 tun_flow_save_rps_rxhash(e, rxhash);
766                 }
767         }
768 
769         tun_debug(KERN_INFO, tun, "tun_net_xmit %d\n", skb->len);
770 
771         BUG_ON(!tfile);
772 
773         /* Drop if the filter does not like it.
774          * This is a noop if the filter is disabled.
775          * Filter can be enabled only for the TAP devices. */
776         if (!check_filter(&tun->txflt, skb))
777                 goto drop;
778 
779         if (tfile->socket.sk->sk_filter &&
780             sk_filter(tfile->socket.sk, skb))
781                 goto drop;
782 
783         /* Limit the number of packets queued by dividing txq length with the
784          * number of queues.
785          */
786         if (skb_queue_len(&tfile->socket.sk->sk_receive_queue) * numqueues
787                           >= dev->tx_queue_len)
788                 goto drop;
789 
790         if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC)))
791                 goto drop;
792 
793         if (skb->sk) {
794                 sock_tx_timestamp(skb->sk, &skb_shinfo(skb)->tx_flags);
795                 sw_tx_timestamp(skb);
796         }
797 
798         /* Orphan the skb - required as we might hang on to it
799          * for indefinite time.
800          */
801         skb_orphan(skb);
802 
803         nf_reset(skb);
804 
805         /* Enqueue packet */
806         skb_queue_tail(&tfile->socket.sk->sk_receive_queue, skb);
807 
808         /* Notify and wake up reader process */
809         if (tfile->flags & TUN_FASYNC)
810                 kill_fasync(&tfile->fasync, SIGIO, POLL_IN);
811         tfile->socket.sk->sk_data_ready(tfile->socket.sk);
812 
813         rcu_read_unlock();
814         return NETDEV_TX_OK;
815 
816 drop:
817         dev->stats.tx_dropped++;
818         skb_tx_error(skb);
819         kfree_skb(skb);
820         rcu_read_unlock();
821         return NETDEV_TX_OK;
822 }
823 
824 static void tun_net_mclist(struct net_device *dev)
825 {
826         /*
827          * This callback is supposed to deal with mc filter in
828          * _rx_ path and has nothing to do with the _tx_ path.
829          * In rx path we always accept everything userspace gives us.
830          */
831 }
832 
833 #define MIN_MTU 68
834 #define MAX_MTU 65535
835 
836 static int
837 tun_net_change_mtu(struct net_device *dev, int new_mtu)
838 {
839         if (new_mtu < MIN_MTU || new_mtu + dev->hard_header_len > MAX_MTU)
840                 return -EINVAL;
841         dev->mtu = new_mtu;
842         return 0;
843 }
844 
845 static netdev_features_t tun_net_fix_features(struct net_device *dev,
846         netdev_features_t features)
847 {
848         struct tun_struct *tun = netdev_priv(dev);
849 
850         return (features & tun->set_features) | (features & ~TUN_USER_FEATURES);
851 }
852 #ifdef CONFIG_NET_POLL_CONTROLLER
853 static void tun_poll_controller(struct net_device *dev)
854 {
855         /*
856          * Tun only receives frames when:
857          * 1) the char device endpoint gets data from user space
858          * 2) the tun socket gets a sendmsg call from user space
859          * Since both of those are synchronous operations, we are guaranteed
860          * never to have pending data when we poll for it
861          * so there is nothing to do here but return.
862          * We need this though so netpoll recognizes us as an interface that
863          * supports polling, which enables bridge devices in virt setups to
864          * still use netconsole
865          */
866         return;
867 }
868 #endif
869 static const struct net_device_ops tun_netdev_ops = {
870         .ndo_uninit             = tun_net_uninit,
871         .ndo_open               = tun_net_open,
872         .ndo_stop               = tun_net_close,
873         .ndo_start_xmit         = tun_net_xmit,
874         .ndo_change_mtu         = tun_net_change_mtu,
875         .ndo_fix_features       = tun_net_fix_features,
876         .ndo_select_queue       = tun_select_queue,
877 #ifdef CONFIG_NET_POLL_CONTROLLER
878         .ndo_poll_controller    = tun_poll_controller,
879 #endif
880 };
881 
882 static const struct net_device_ops tap_netdev_ops = {
883         .ndo_uninit             = tun_net_uninit,
884         .ndo_open               = tun_net_open,
885         .ndo_stop               = tun_net_close,
886         .ndo_start_xmit         = tun_net_xmit,
887         .ndo_change_mtu         = tun_net_change_mtu,
888         .ndo_fix_features       = tun_net_fix_features,
889         .ndo_set_rx_mode        = tun_net_mclist,
890         .ndo_set_mac_address    = eth_mac_addr,
891         .ndo_validate_addr      = eth_validate_addr,
892         .ndo_select_queue       = tun_select_queue,
893 #ifdef CONFIG_NET_POLL_CONTROLLER
894         .ndo_poll_controller    = tun_poll_controller,
895 #endif
896 };
897 
898 static void tun_flow_init(struct tun_struct *tun)
899 {
900         int i;
901 
902         for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++)
903                 INIT_HLIST_HEAD(&tun->flows[i]);
904 
905         tun->ageing_time = TUN_FLOW_EXPIRE;
906         setup_timer(&tun->flow_gc_timer, tun_flow_cleanup, (unsigned long)tun);
907         mod_timer(&tun->flow_gc_timer,
908                   round_jiffies_up(jiffies + tun->ageing_time));
909 }
910 
911 static void tun_flow_uninit(struct tun_struct *tun)
912 {
913         del_timer_sync(&tun->flow_gc_timer);
914         tun_flow_flush(tun);
915 }
916 
917 /* Initialize net device. */
918 static void tun_net_init(struct net_device *dev)
919 {
920         struct tun_struct *tun = netdev_priv(dev);
921 
922         switch (tun->flags & TUN_TYPE_MASK) {
923         case TUN_TUN_DEV:
924                 dev->netdev_ops = &tun_netdev_ops;
925 
926                 /* Point-to-Point TUN Device */
927                 dev->hard_header_len = 0;
928                 dev->addr_len = 0;
929                 dev->mtu = 1500;
930 
931                 /* Zero header length */
932                 dev->type = ARPHRD_NONE;
933                 dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
934                 dev->tx_queue_len = TUN_READQ_SIZE;  /* We prefer our own queue length */
935                 break;
936 
937         case TUN_TAP_DEV:
938                 dev->netdev_ops = &tap_netdev_ops;
939                 /* Ethernet TAP Device */
940                 ether_setup(dev);
941                 dev->priv_flags &= ~IFF_TX_SKB_SHARING;
942                 dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
943 
944                 eth_hw_addr_random(dev);
945 
946                 dev->tx_queue_len = TUN_READQ_SIZE;  /* We prefer our own queue length */
947                 break;
948         }
949 }
950 
951 /* Character device part */
952 
953 /* Poll */
954 static unsigned int tun_chr_poll(struct file *file, poll_table *wait)
955 {
956         struct tun_file *tfile = file->private_data;
957         struct tun_struct *tun = __tun_get(tfile);
958         struct sock *sk;
959         unsigned int mask = 0;
960 
961         if (!tun)
962                 return POLLERR;
963 
964         sk = tfile->socket.sk;
965 
966         tun_debug(KERN_INFO, tun, "tun_chr_poll\n");
967 
968         poll_wait(file, sk_sleep(sk), wait);
969 
970         if (!skb_queue_empty(&sk->sk_receive_queue))
971                 mask |= POLLIN | POLLRDNORM;
972 
973         if (sock_writeable(sk) ||
974             (!test_and_set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags) &&
975              sock_writeable(sk)))
976                 mask |= POLLOUT | POLLWRNORM;
977 
978         if (tun->dev->reg_state != NETREG_REGISTERED)
979                 mask = POLLERR;
980 
981         tun_put(tun);
982         return mask;
983 }
984 
985 /* prepad is the amount to reserve at front.  len is length after that.
986  * linear is a hint as to how much to copy (usually headers). */
987 static struct sk_buff *tun_alloc_skb(struct tun_file *tfile,
988                                      size_t prepad, size_t len,
989                                      size_t linear, int noblock)
990 {
991         struct sock *sk = tfile->socket.sk;
992         struct sk_buff *skb;
993         int err;
994 
995         /* Under a page?  Don't bother with paged skb. */
996         if (prepad + len < PAGE_SIZE || !linear)
997                 linear = len;
998 
999         skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
1000                                    &err, 0);
1001         if (!skb)
1002                 return ERR_PTR(err);
1003 
1004         skb_reserve(skb, prepad);
1005         skb_put(skb, linear);
1006         skb->data_len = len - linear;
1007         skb->len += len - linear;
1008 
1009         return skb;
1010 }
1011 
1012 /* Get packet from user space buffer */
1013 static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
1014                             void *msg_control, const struct iovec *iv,
1015                             size_t total_len, size_t count, int noblock)
1016 {
1017         struct tun_pi pi = { 0, cpu_to_be16(ETH_P_IP) };
1018         struct sk_buff *skb;
1019         size_t len = total_len, align = NET_SKB_PAD, linear;
1020         struct virtio_net_hdr gso = { 0 };
1021         int good_linear;
1022         int offset = 0;
1023         int copylen;
1024         bool zerocopy = false;
1025         int err;
1026         u32 rxhash;
1027 
1028         if (!(tun->flags & TUN_NO_PI)) {
1029                 if (len < sizeof(pi))
1030                         return -EINVAL;
1031                 len -= sizeof(pi);
1032 
1033                 if (memcpy_fromiovecend((void *)&pi, iv, 0, sizeof(pi)))
1034                         return -EFAULT;
1035                 offset += sizeof(pi);
1036         }
1037 
1038         if (tun->flags & TUN_VNET_HDR) {
1039                 if (len < tun->vnet_hdr_sz)
1040                         return -EINVAL;
1041                 len -= tun->vnet_hdr_sz;
1042 
1043                 if (memcpy_fromiovecend((void *)&gso, iv, offset, sizeof(gso)))
1044                         return -EFAULT;
1045 
1046                 if ((gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
1047                     gso.csum_start + gso.csum_offset + 2 > gso.hdr_len)
1048                         gso.hdr_len = gso.csum_start + gso.csum_offset + 2;
1049 
1050                 if (gso.hdr_len > len)
1051                         return -EINVAL;
1052                 offset += tun->vnet_hdr_sz;
1053         }
1054 
1055         if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV) {
1056                 align += NET_IP_ALIGN;
1057                 if (unlikely(len < ETH_HLEN ||
1058                              (gso.hdr_len && gso.hdr_len < ETH_HLEN)))
1059                         return -EINVAL;
1060         }
1061 
1062         good_linear = SKB_MAX_HEAD(align);
1063 
1064         if (msg_control) {
1065                 /* There are 256 bytes to be copied in skb, so there is
1066                  * enough room for skb expand head in case it is used.
1067                  * The rest of the buffer is mapped from userspace.
1068                  */
1069                 copylen = gso.hdr_len ? gso.hdr_len : GOODCOPY_LEN;
1070                 if (copylen > good_linear)
1071                         copylen = good_linear;
1072                 linear = copylen;
1073                 if (iov_pages(iv, offset + copylen, count) <= MAX_SKB_FRAGS)
1074                         zerocopy = true;
1075         }
1076 
1077         if (!zerocopy) {
1078                 copylen = len;
1079                 if (gso.hdr_len > good_linear)
1080                         linear = good_linear;
1081                 else
1082                         linear = gso.hdr_len;
1083         }
1084 
1085         skb = tun_alloc_skb(tfile, align, copylen, linear, noblock);
1086         if (IS_ERR(skb)) {
1087                 if (PTR_ERR(skb) != -EAGAIN)
1088                         tun->dev->stats.rx_dropped++;
1089                 return PTR_ERR(skb);
1090         }
1091 
1092         if (zerocopy)
1093                 err = zerocopy_sg_from_iovec(skb, iv, offset, count);
1094         else {
1095                 err = skb_copy_datagram_from_iovec(skb, 0, iv, offset, len);
1096                 if (!err && msg_control) {
1097                         struct ubuf_info *uarg = msg_control;
1098                         uarg->callback(uarg, false);
1099                 }
1100         }
1101 
1102         if (err) {
1103                 tun->dev->stats.rx_dropped++;
1104                 kfree_skb(skb);
1105                 return -EFAULT;
1106         }
1107 
1108         if (gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
1109                 if (!skb_partial_csum_set(skb, gso.csum_start,
1110                                           gso.csum_offset)) {
1111                         tun->dev->stats.rx_frame_errors++;
1112                         kfree_skb(skb);
1113                         return -EINVAL;
1114                 }
1115         }
1116 
1117         switch (tun->flags & TUN_TYPE_MASK) {
1118         case TUN_TUN_DEV:
1119                 if (tun->flags & TUN_NO_PI) {
1120                         switch (skb->data[0] & 0xf0) {
1121                         case 0x40:
1122                                 pi.proto = htons(ETH_P_IP);
1123                                 break;
1124                         case 0x60:
1125                                 pi.proto = htons(ETH_P_IPV6);
1126                                 break;
1127                         default:
1128                                 tun->dev->stats.rx_dropped++;
1129                                 kfree_skb(skb);
1130                                 return -EINVAL;
1131                         }
1132                 }
1133 
1134                 skb_reset_mac_header(skb);
1135                 skb->protocol = pi.proto;
1136                 skb->dev = tun->dev;
1137                 break;
1138         case TUN_TAP_DEV:
1139                 skb->protocol = eth_type_trans(skb, tun->dev);
1140                 break;
1141         }
1142 
1143         skb_reset_network_header(skb);
1144 
1145         if (gso.gso_type != VIRTIO_NET_HDR_GSO_NONE) {
1146                 pr_debug("GSO!\n");
1147                 switch (gso.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
1148                 case VIRTIO_NET_HDR_GSO_TCPV4:
1149                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
1150                         break;
1151                 case VIRTIO_NET_HDR_GSO_TCPV6:
1152                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
1153                         break;
1154                 case VIRTIO_NET_HDR_GSO_UDP:
1155                 {
1156                         static bool warned;
1157 
1158                         if (!warned) {
1159                                 warned = true;
1160                                 netdev_warn(tun->dev,
1161                                             "%s: using disabled UFO feature; please fix this program\n",
1162                                             current->comm);
1163                         }
1164                         skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1165                         if (skb->protocol == htons(ETH_P_IPV6))
1166                                 ipv6_proxy_select_ident(skb);
1167                         break;
1168                 }
1169                 default:
1170                         tun->dev->stats.rx_frame_errors++;
1171                         kfree_skb(skb);
1172                         return -EINVAL;
1173                 }
1174 
1175                 if (gso.gso_type & VIRTIO_NET_HDR_GSO_ECN)
1176                         skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
1177 
1178                 skb_shinfo(skb)->gso_size = gso.gso_size;
1179                 if (skb_shinfo(skb)->gso_size == 0) {
1180                         tun->dev->stats.rx_frame_errors++;
1181                         kfree_skb(skb);
1182                         return -EINVAL;
1183                 }
1184 
1185                 /* Header must be checked, and gso_segs computed. */
1186                 skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
1187                 skb_shinfo(skb)->gso_segs = 0;
1188         }
1189 
1190         /* copy skb_ubuf_info for callback when skb has no error */
1191         if (zerocopy) {
1192                 skb_shinfo(skb)->destructor_arg = msg_control;
1193                 skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
1194                 skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
1195         }
1196 
1197         skb_probe_transport_header(skb, 0);
1198 
1199         rxhash = skb_get_hash(skb);
1200         netif_rx_ni(skb);
1201 
1202         tun->dev->stats.rx_packets++;
1203         tun->dev->stats.rx_bytes += len;
1204 
1205         tun_flow_update(tun, rxhash, tfile);
1206         return total_len;
1207 }
1208 
1209 static ssize_t tun_chr_aio_write(struct kiocb *iocb, const struct iovec *iv,
1210                               unsigned long count, loff_t pos)
1211 {
1212         struct file *file = iocb->ki_filp;
1213         struct tun_struct *tun = tun_get(file);
1214         struct tun_file *tfile = file->private_data;
1215         ssize_t result;
1216 
1217         if (!tun)
1218                 return -EBADFD;
1219 
1220         tun_debug(KERN_INFO, tun, "tun_chr_write %ld\n", count);
1221 
1222         result = tun_get_user(tun, tfile, NULL, iv, iov_length(iv, count),
1223                               count, file->f_flags & O_NONBLOCK);
1224 
1225         tun_put(tun);
1226         return result;
1227 }
1228 
1229 /* Put packet to the user space buffer */
1230 static ssize_t tun_put_user(struct tun_struct *tun,
1231                             struct tun_file *tfile,
1232                             struct sk_buff *skb,
1233                             const struct iovec *iv, int len)
1234 {
1235         struct tun_pi pi = { 0, skb->protocol };
1236         ssize_t total = 0;
1237         int vlan_offset = 0, copied;
1238         int vlan_hlen = 0;
1239         int vnet_hdr_sz = 0;
1240 
1241         if (vlan_tx_tag_present(skb))
1242                 vlan_hlen = VLAN_HLEN;
1243 
1244         if (tun->flags & TUN_VNET_HDR)
1245                 vnet_hdr_sz = tun->vnet_hdr_sz;
1246 
1247         if (!(tun->flags & TUN_NO_PI)) {
1248                 if ((len -= sizeof(pi)) < 0)
1249                         return -EINVAL;
1250 
1251                 if (len < skb->len + vlan_hlen + vnet_hdr_sz) {
1252                         /* Packet will be striped */
1253                         pi.flags |= TUN_PKT_STRIP;
1254                 }
1255 
1256                 if (memcpy_toiovecend(iv, (void *) &pi, 0, sizeof(pi)))
1257                         return -EFAULT;
1258                 total += sizeof(pi);
1259         }
1260 
1261         if (vnet_hdr_sz) {
1262                 struct virtio_net_hdr gso = { 0 }; /* no info leak */
1263                 if ((len -= vnet_hdr_sz) < 0)
1264                         return -EINVAL;
1265 
1266                 if (skb_is_gso(skb)) {
1267                         struct skb_shared_info *sinfo = skb_shinfo(skb);
1268 
1269                         /* This is a hint as to how much should be linear. */
1270                         gso.hdr_len = skb_headlen(skb);
1271                         gso.gso_size = sinfo->gso_size;
1272                         if (sinfo->gso_type & SKB_GSO_TCPV4)
1273                                 gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
1274                         else if (sinfo->gso_type & SKB_GSO_TCPV6)
1275                                 gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
1276                         else {
1277                                 pr_err("unexpected GSO type: "
1278                                        "0x%x, gso_size %d, hdr_len %d\n",
1279                                        sinfo->gso_type, gso.gso_size,
1280                                        gso.hdr_len);
1281                                 print_hex_dump(KERN_ERR, "tun: ",
1282                                                DUMP_PREFIX_NONE,
1283                                                16, 1, skb->head,
1284                                                min((int)gso.hdr_len, 64), true);
1285                                 WARN_ON_ONCE(1);
1286                                 return -EINVAL;
1287                         }
1288                         if (sinfo->gso_type & SKB_GSO_TCP_ECN)
1289                                 gso.gso_type |= VIRTIO_NET_HDR_GSO_ECN;
1290                 } else
1291                         gso.gso_type = VIRTIO_NET_HDR_GSO_NONE;
1292 
1293                 if (skb->ip_summed == CHECKSUM_PARTIAL) {
1294                         gso.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
1295                         gso.csum_start = skb_checksum_start_offset(skb) +
1296                                          vlan_hlen;
1297                         gso.csum_offset = skb->csum_offset;
1298                 } else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
1299                         gso.flags = VIRTIO_NET_HDR_F_DATA_VALID;
1300                 } /* else everything is zero */
1301 
1302                 if (unlikely(memcpy_toiovecend(iv, (void *)&gso, total,
1303                                                sizeof(gso))))
1304                         return -EFAULT;
1305                 total += vnet_hdr_sz;
1306         }
1307 
1308         copied = total;
1309         len = min_t(int, skb->len + vlan_hlen, len);
1310         total += skb->len + vlan_hlen;
1311         if (vlan_hlen) {
1312                 int copy, ret;
1313                 struct {
1314                         __be16 h_vlan_proto;
1315                         __be16 h_vlan_TCI;
1316                 } veth;
1317 
1318                 veth.h_vlan_proto = skb->vlan_proto;
1319                 veth.h_vlan_TCI = htons(vlan_tx_tag_get(skb));
1320 
1321                 vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
1322 
1323                 copy = min_t(int, vlan_offset, len);
1324                 ret = skb_copy_datagram_const_iovec(skb, 0, iv, copied, copy);
1325                 len -= copy;
1326                 copied += copy;
1327                 if (ret || !len)
1328                         goto done;
1329 
1330                 copy = min_t(int, sizeof(veth), len);
1331                 ret = memcpy_toiovecend(iv, (void *)&veth, copied, copy);
1332                 len -= copy;
1333                 copied += copy;
1334                 if (ret || !len)
1335                         goto done;
1336         }
1337 
1338         skb_copy_datagram_const_iovec(skb, vlan_offset, iv, copied, len);
1339 
1340 done:
1341         tun->dev->stats.tx_packets++;
1342         tun->dev->stats.tx_bytes += len;
1343 
1344         return total;
1345 }
1346 
1347 static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
1348                            const struct iovec *iv, ssize_t len, int noblock)
1349 {
1350         struct sk_buff *skb;
1351         ssize_t ret = 0;
1352         int peeked, err, off = 0;
1353 
1354         tun_debug(KERN_INFO, tun, "tun_do_read\n");
1355 
1356         if (!len)
1357                 return ret;
1358 
1359         if (tun->dev->reg_state != NETREG_REGISTERED)
1360                 return -EIO;
1361 
1362         /* Read frames from queue */
1363         skb = __skb_recv_datagram(tfile->socket.sk, noblock ? MSG_DONTWAIT : 0,
1364                                   &peeked, &off, &err);
1365         if (skb) {
1366                 ret = tun_put_user(tun, tfile, skb, iv, len);
1367                 kfree_skb(skb);
1368         } else
1369                 ret = err;
1370 
1371         return ret;
1372 }
1373 
1374 static ssize_t tun_chr_aio_read(struct kiocb *iocb, const struct iovec *iv,
1375                             unsigned long count, loff_t pos)
1376 {
1377         struct file *file = iocb->ki_filp;
1378         struct tun_file *tfile = file->private_data;
1379         struct tun_struct *tun = __tun_get(tfile);
1380         ssize_t len, ret;
1381 
1382         if (!tun)
1383                 return -EBADFD;
1384         len = iov_length(iv, count);
1385         if (len < 0) {
1386                 ret = -EINVAL;
1387                 goto out;
1388         }
1389 
1390         ret = tun_do_read(tun, tfile, iv, len,
1391                           file->f_flags & O_NONBLOCK);
1392         ret = min_t(ssize_t, ret, len);
1393         if (ret > 0)
1394                 iocb->ki_pos = ret;
1395 out:
1396         tun_put(tun);
1397         return ret;
1398 }
1399 
1400 static void tun_free_netdev(struct net_device *dev)
1401 {
1402         struct tun_struct *tun = netdev_priv(dev);
1403 
1404         BUG_ON(!(list_empty(&tun->disabled)));
1405         tun_flow_uninit(tun);
1406         security_tun_dev_free_security(tun->security);
1407         free_netdev(dev);
1408 }
1409 
1410 static void tun_setup(struct net_device *dev)
1411 {
1412         struct tun_struct *tun = netdev_priv(dev);
1413 
1414         tun->owner = INVALID_UID;
1415         tun->group = INVALID_GID;
1416 
1417         dev->ethtool_ops = &tun_ethtool_ops;
1418         dev->destructor = tun_free_netdev;
1419 }
1420 
1421 /* Trivial set of netlink ops to allow deleting tun or tap
1422  * device with netlink.
1423  */
1424 static int tun_validate(struct nlattr *tb[], struct nlattr *data[])
1425 {
1426         return -EINVAL;
1427 }
1428 
1429 static struct rtnl_link_ops tun_link_ops __read_mostly = {
1430         .kind           = DRV_NAME,
1431         .priv_size      = sizeof(struct tun_struct),
1432         .setup          = tun_setup,
1433         .validate       = tun_validate,
1434 };
1435 
1436 static void tun_sock_write_space(struct sock *sk)
1437 {
1438         struct tun_file *tfile;
1439         wait_queue_head_t *wqueue;
1440 
1441         if (!sock_writeable(sk))
1442                 return;
1443 
1444         if (!test_and_clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags))
1445                 return;
1446 
1447         wqueue = sk_sleep(sk);
1448         if (wqueue && waitqueue_active(wqueue))
1449                 wake_up_interruptible_sync_poll(wqueue, POLLOUT |
1450                                                 POLLWRNORM | POLLWRBAND);
1451 
1452         tfile = container_of(sk, struct tun_file, sk);
1453         kill_fasync(&tfile->fasync, SIGIO, POLL_OUT);
1454 }
1455 
1456 static int tun_sendmsg(struct kiocb *iocb, struct socket *sock,
1457                        struct msghdr *m, size_t total_len)
1458 {
1459         int ret;
1460         struct tun_file *tfile = container_of(sock, struct tun_file, socket);
1461         struct tun_struct *tun = __tun_get(tfile);
1462 
1463         if (!tun)
1464                 return -EBADFD;
1465         ret = tun_get_user(tun, tfile, m->msg_control, m->msg_iov, total_len,
1466                            m->msg_iovlen, m->msg_flags & MSG_DONTWAIT);
1467         tun_put(tun);
1468         return ret;
1469 }
1470 
1471 static int tun_recvmsg(struct kiocb *iocb, struct socket *sock,
1472                        struct msghdr *m, size_t total_len,
1473                        int flags)
1474 {
1475         struct tun_file *tfile = container_of(sock, struct tun_file, socket);
1476         struct tun_struct *tun = __tun_get(tfile);
1477         int ret;
1478 
1479         if (!tun)
1480                 return -EBADFD;
1481 
1482         if (flags & ~(MSG_DONTWAIT|MSG_TRUNC|MSG_ERRQUEUE)) {
1483                 ret = -EINVAL;
1484                 goto out;
1485         }
1486         if (flags & MSG_ERRQUEUE) {
1487                 ret = sock_recv_errqueue(sock->sk, m, total_len,
1488                                          SOL_PACKET, TUN_TX_TIMESTAMP);
1489                 goto out;
1490         }
1491         ret = tun_do_read(tun, tfile, m->msg_iov, total_len,
1492                           flags & MSG_DONTWAIT);
1493         if (ret > total_len) {
1494                 m->msg_flags |= MSG_TRUNC;
1495                 ret = flags & MSG_TRUNC ? ret : total_len;
1496         }
1497 out:
1498         tun_put(tun);
1499         return ret;
1500 }
1501 
1502 static int tun_release(struct socket *sock)
1503 {
1504         if (sock->sk)
1505                 sock_put(sock->sk);
1506         return 0;
1507 }
1508 
1509 /* Ops structure to mimic raw sockets with tun */
1510 static const struct proto_ops tun_socket_ops = {
1511         .sendmsg = tun_sendmsg,
1512         .recvmsg = tun_recvmsg,
1513         .release = tun_release,
1514 };
1515 
1516 static struct proto tun_proto = {
1517         .name           = "tun",
1518         .owner          = THIS_MODULE,
1519         .obj_size       = sizeof(struct tun_file),
1520 };
1521 
1522 static int tun_flags(struct tun_struct *tun)
1523 {
1524         int flags = 0;
1525 
1526         if (tun->flags & TUN_TUN_DEV)
1527                 flags |= IFF_TUN;
1528         else
1529                 flags |= IFF_TAP;
1530 
1531         if (tun->flags & TUN_NO_PI)
1532                 flags |= IFF_NO_PI;
1533 
1534         /* This flag has no real effect.  We track the value for backwards
1535          * compatibility.
1536          */
1537         if (tun->flags & TUN_ONE_QUEUE)
1538                 flags |= IFF_ONE_QUEUE;
1539 
1540         if (tun->flags & TUN_VNET_HDR)
1541                 flags |= IFF_VNET_HDR;
1542 
1543         if (tun->flags & TUN_TAP_MQ)
1544                 flags |= IFF_MULTI_QUEUE;
1545 
1546         if (tun->flags & TUN_PERSIST)
1547                 flags |= IFF_PERSIST;
1548 
1549         return flags;
1550 }
1551 
1552 static ssize_t tun_show_flags(struct device *dev, struct device_attribute *attr,
1553                               char *buf)
1554 {
1555         struct tun_struct *tun = netdev_priv(to_net_dev(dev));
1556         return sprintf(buf, "0x%x\n", tun_flags(tun));
1557 }
1558 
1559 static ssize_t tun_show_owner(struct device *dev, struct device_attribute *attr,
1560                               char *buf)
1561 {
1562         struct tun_struct *tun = netdev_priv(to_net_dev(dev));
1563         return uid_valid(tun->owner)?
1564                 sprintf(buf, "%u\n",
1565                         from_kuid_munged(current_user_ns(), tun->owner)):
1566                 sprintf(buf, "-1\n");
1567 }
1568 
1569 static ssize_t tun_show_group(struct device *dev, struct device_attribute *attr,
1570                               char *buf)
1571 {
1572         struct tun_struct *tun = netdev_priv(to_net_dev(dev));
1573         return gid_valid(tun->group) ?
1574                 sprintf(buf, "%u\n",
1575                         from_kgid_munged(current_user_ns(), tun->group)):
1576                 sprintf(buf, "-1\n");
1577 }
1578 
1579 static DEVICE_ATTR(tun_flags, 0444, tun_show_flags, NULL);
1580 static DEVICE_ATTR(owner, 0444, tun_show_owner, NULL);
1581 static DEVICE_ATTR(group, 0444, tun_show_group, NULL);
1582 
1583 static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
1584 {
1585         struct tun_struct *tun;
1586         struct tun_file *tfile = file->private_data;
1587         struct net_device *dev;
1588         int err;
1589 
1590         if (tfile->detached)
1591                 return -EINVAL;
1592 
1593         dev = __dev_get_by_name(net, ifr->ifr_name);
1594         if (dev) {
1595                 if (ifr->ifr_flags & IFF_TUN_EXCL)
1596                         return -EBUSY;
1597                 if ((ifr->ifr_flags & IFF_TUN) && dev->netdev_ops == &tun_netdev_ops)
1598                         tun = netdev_priv(dev);
1599                 else if ((ifr->ifr_flags & IFF_TAP) && dev->netdev_ops == &tap_netdev_ops)
1600                         tun = netdev_priv(dev);
1601                 else
1602                         return -EINVAL;
1603 
1604                 if (!!(ifr->ifr_flags & IFF_MULTI_QUEUE) !=
1605                     !!(tun->flags & TUN_TAP_MQ))
1606                         return -EINVAL;
1607 
1608                 if (tun_not_capable(tun))
1609                         return -EPERM;
1610                 err = security_tun_dev_open(tun->security);
1611                 if (err < 0)
1612                         return err;
1613 
1614                 err = tun_attach(tun, file, ifr->ifr_flags & IFF_NOFILTER);
1615                 if (err < 0)
1616                         return err;
1617 
1618                 if (tun->flags & TUN_TAP_MQ &&
1619                     (tun->numqueues + tun->numdisabled > 1)) {
1620                         /* One or more queue has already been attached, no need
1621                          * to initialize the device again.
1622                          */
1623                         return 0;
1624                 }
1625         }
1626         else {
1627                 char *name;
1628                 unsigned long flags = 0;
1629                 int queues = ifr->ifr_flags & IFF_MULTI_QUEUE ?
1630                              MAX_TAP_QUEUES : 1;
1631 
1632                 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1633                         return -EPERM;
1634                 err = security_tun_dev_create();
1635                 if (err < 0)
1636                         return err;
1637 
1638                 /* Set dev type */
1639                 if (ifr->ifr_flags & IFF_TUN) {
1640                         /* TUN device */
1641                         flags |= TUN_TUN_DEV;
1642                         name = "tun%d";
1643                 } else if (ifr->ifr_flags & IFF_TAP) {
1644                         /* TAP device */
1645                         flags |= TUN_TAP_DEV;
1646                         name = "tap%d";
1647                 } else
1648                         return -EINVAL;
1649 
1650                 if (*ifr->ifr_name)
1651                         name = ifr->ifr_name;
1652 
1653                 dev = alloc_netdev_mqs(sizeof(struct tun_struct), name,
1654                                        NET_NAME_UNKNOWN, tun_setup, queues,
1655                                        queues);
1656 
1657                 if (!dev)
1658                         return -ENOMEM;
1659 
1660                 dev_net_set(dev, net);
1661                 dev->rtnl_link_ops = &tun_link_ops;
1662                 dev->ifindex = tfile->ifindex;
1663 
1664                 tun = netdev_priv(dev);
1665                 tun->dev = dev;
1666                 tun->flags = flags;
1667                 tun->txflt.count = 0;
1668                 tun->vnet_hdr_sz = sizeof(struct virtio_net_hdr);
1669 
1670                 tun->filter_attached = false;
1671                 tun->sndbuf = tfile->socket.sk->sk_sndbuf;
1672 
1673                 spin_lock_init(&tun->lock);
1674 
1675                 err = security_tun_dev_alloc_security(&tun->security);
1676                 if (err < 0)
1677                         goto err_free_dev;
1678 
1679                 tun_net_init(dev);
1680                 tun_flow_init(tun);
1681 
1682                 dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST |
1683                                    TUN_USER_FEATURES | NETIF_F_HW_VLAN_CTAG_TX |
1684                                    NETIF_F_HW_VLAN_STAG_TX;
1685                 dev->features = dev->hw_features;
1686                 dev->vlan_features = dev->features &
1687                                      ~(NETIF_F_HW_VLAN_CTAG_TX |
1688                                        NETIF_F_HW_VLAN_STAG_TX);
1689 
1690                 INIT_LIST_HEAD(&tun->disabled);
1691                 err = tun_attach(tun, file, false);
1692                 if (err < 0)
1693                         goto err_free_flow;
1694 
1695                 err = register_netdevice(tun->dev);
1696                 if (err < 0)
1697                         goto err_detach;
1698 
1699                 if (device_create_file(&tun->dev->dev, &dev_attr_tun_flags) ||
1700                     device_create_file(&tun->dev->dev, &dev_attr_owner) ||
1701                     device_create_file(&tun->dev->dev, &dev_attr_group))
1702                         pr_err("Failed to create tun sysfs files\n");
1703         }
1704 
1705         netif_carrier_on(tun->dev);
1706 
1707         tun_debug(KERN_INFO, tun, "tun_set_iff\n");
1708 
1709         if (ifr->ifr_flags & IFF_NO_PI)
1710                 tun->flags |= TUN_NO_PI;
1711         else
1712                 tun->flags &= ~TUN_NO_PI;
1713 
1714         /* This flag has no real effect.  We track the value for backwards
1715          * compatibility.
1716          */
1717         if (ifr->ifr_flags & IFF_ONE_QUEUE)
1718                 tun->flags |= TUN_ONE_QUEUE;
1719         else
1720                 tun->flags &= ~TUN_ONE_QUEUE;
1721 
1722         if (ifr->ifr_flags & IFF_VNET_HDR)
1723                 tun->flags |= TUN_VNET_HDR;
1724         else
1725                 tun->flags &= ~TUN_VNET_HDR;
1726 
1727         if (ifr->ifr_flags & IFF_MULTI_QUEUE)
1728                 tun->flags |= TUN_TAP_MQ;
1729         else
1730                 tun->flags &= ~TUN_TAP_MQ;
1731 
1732         /* Make sure persistent devices do not get stuck in
1733          * xoff state.
1734          */
1735         if (netif_running(tun->dev))
1736                 netif_tx_wake_all_queues(tun->dev);
1737 
1738         strcpy(ifr->ifr_name, tun->dev->name);
1739         return 0;
1740 
1741 err_detach:
1742         tun_detach_all(dev);
1743 err_free_flow:
1744         tun_flow_uninit(tun);
1745         security_tun_dev_free_security(tun->security);
1746 err_free_dev:
1747         free_netdev(dev);
1748         return err;
1749 }
1750 
1751 static void tun_get_iff(struct net *net, struct tun_struct *tun,
1752                        struct ifreq *ifr)
1753 {
1754         tun_debug(KERN_INFO, tun, "tun_get_iff\n");
1755 
1756         strcpy(ifr->ifr_name, tun->dev->name);
1757 
1758         ifr->ifr_flags = tun_flags(tun);
1759 
1760 }
1761 
1762 /* This is like a cut-down ethtool ops, except done via tun fd so no
1763  * privs required. */
1764 static int set_offload(struct tun_struct *tun, unsigned long arg)
1765 {
1766         netdev_features_t features = 0;
1767 
1768         if (arg & TUN_F_CSUM) {
1769                 features |= NETIF_F_HW_CSUM;
1770                 arg &= ~TUN_F_CSUM;
1771 
1772                 if (arg & (TUN_F_TSO4|TUN_F_TSO6)) {
1773                         if (arg & TUN_F_TSO_ECN) {
1774                                 features |= NETIF_F_TSO_ECN;
1775                                 arg &= ~TUN_F_TSO_ECN;
1776                         }
1777                         if (arg & TUN_F_TSO4)
1778                                 features |= NETIF_F_TSO;
1779                         if (arg & TUN_F_TSO6)
1780                                 features |= NETIF_F_TSO6;
1781                         arg &= ~(TUN_F_TSO4|TUN_F_TSO6);
1782                 }
1783         }
1784 
1785         /* This gives the user a way to test for new features in future by
1786          * trying to set them. */
1787         if (arg)
1788                 return -EINVAL;
1789 
1790         tun->set_features = features;
1791         netdev_update_features(tun->dev);
1792 
1793         return 0;
1794 }
1795 
1796 static void tun_detach_filter(struct tun_struct *tun, int n)
1797 {
1798         int i;
1799         struct tun_file *tfile;
1800 
1801         for (i = 0; i < n; i++) {
1802                 tfile = rtnl_dereference(tun->tfiles[i]);
1803                 sk_detach_filter(tfile->socket.sk);
1804         }
1805 
1806         tun->filter_attached = false;
1807 }
1808 
1809 static int tun_attach_filter(struct tun_struct *tun)
1810 {
1811         int i, ret = 0;
1812         struct tun_file *tfile;
1813 
1814         for (i = 0; i < tun->numqueues; i++) {
1815                 tfile = rtnl_dereference(tun->tfiles[i]);
1816                 ret = sk_attach_filter(&tun->fprog, tfile->socket.sk);
1817                 if (ret) {
1818                         tun_detach_filter(tun, i);
1819                         return ret;
1820                 }
1821         }
1822 
1823         tun->filter_attached = true;
1824         return ret;
1825 }
1826 
1827 static void tun_set_sndbuf(struct tun_struct *tun)
1828 {
1829         struct tun_file *tfile;
1830         int i;
1831 
1832         for (i = 0; i < tun->numqueues; i++) {
1833                 tfile = rtnl_dereference(tun->tfiles[i]);
1834                 tfile->socket.sk->sk_sndbuf = tun->sndbuf;
1835         }
1836 }
1837 
1838 static int tun_set_queue(struct file *file, struct ifreq *ifr)
1839 {
1840         struct tun_file *tfile = file->private_data;
1841         struct tun_struct *tun;
1842         int ret = 0;
1843 
1844         rtnl_lock();
1845 
1846         if (ifr->ifr_flags & IFF_ATTACH_QUEUE) {
1847                 tun = tfile->detached;
1848                 if (!tun) {
1849                         ret = -EINVAL;
1850                         goto unlock;
1851                 }
1852                 ret = security_tun_dev_attach_queue(tun->security);
1853                 if (ret < 0)
1854                         goto unlock;
1855                 ret = tun_attach(tun, file, false);
1856         } else if (ifr->ifr_flags & IFF_DETACH_QUEUE) {
1857                 tun = rtnl_dereference(tfile->tun);
1858                 if (!tun || !(tun->flags & TUN_TAP_MQ) || tfile->detached)
1859                         ret = -EINVAL;
1860                 else
1861                         __tun_detach(tfile, false);
1862         } else
1863                 ret = -EINVAL;
1864 
1865 unlock:
1866         rtnl_unlock();
1867         return ret;
1868 }
1869 
1870 static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
1871                             unsigned long arg, int ifreq_len)
1872 {
1873         struct tun_file *tfile = file->private_data;
1874         struct tun_struct *tun;
1875         void __user* argp = (void __user*)arg;
1876         struct ifreq ifr;
1877         kuid_t owner;
1878         kgid_t group;
1879         int sndbuf;
1880         int vnet_hdr_sz;
1881         unsigned int ifindex;
1882         int ret;
1883 
1884         if (cmd == TUNSETIFF || cmd == TUNSETQUEUE || _IOC_TYPE(cmd) == 0x89) {
1885                 if (copy_from_user(&ifr, argp, ifreq_len))
1886                         return -EFAULT;
1887         } else {
1888                 memset(&ifr, 0, sizeof(ifr));
1889         }
1890         if (cmd == TUNGETFEATURES) {
1891                 /* Currently this just means: "what IFF flags are valid?".
1892                  * This is needed because we never checked for invalid flags on
1893                  * TUNSETIFF. */
1894                 return put_user(IFF_TUN | IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE |
1895                                 IFF_VNET_HDR | IFF_MULTI_QUEUE,
1896                                 (unsigned int __user*)argp);
1897         } else if (cmd == TUNSETQUEUE)
1898                 return tun_set_queue(file, &ifr);
1899 
1900         ret = 0;
1901         rtnl_lock();
1902 
1903         tun = __tun_get(tfile);
1904         if (cmd == TUNSETIFF && !tun) {
1905                 ifr.ifr_name[IFNAMSIZ-1] = '\0';
1906 
1907                 ret = tun_set_iff(tfile->net, file, &ifr);
1908 
1909                 if (ret)
1910                         goto unlock;
1911 
1912                 if (copy_to_user(argp, &ifr, ifreq_len))
1913                         ret = -EFAULT;
1914                 goto unlock;
1915         }
1916         if (cmd == TUNSETIFINDEX) {
1917                 ret = -EPERM;
1918                 if (tun)
1919                         goto unlock;
1920 
1921                 ret = -EFAULT;
1922                 if (copy_from_user(&ifindex, argp, sizeof(ifindex)))
1923                         goto unlock;
1924 
1925                 ret = 0;
1926                 tfile->ifindex = ifindex;
1927                 goto unlock;
1928         }
1929 
1930         ret = -EBADFD;
1931         if (!tun)
1932                 goto unlock;
1933 
1934         tun_debug(KERN_INFO, tun, "tun_chr_ioctl cmd %u\n", cmd);
1935 
1936         ret = 0;
1937         switch (cmd) {
1938         case TUNGETIFF:
1939                 tun_get_iff(current->nsproxy->net_ns, tun, &ifr);
1940 
1941                 if (tfile->detached)
1942                         ifr.ifr_flags |= IFF_DETACH_QUEUE;
1943                 if (!tfile->socket.sk->sk_filter)
1944                         ifr.ifr_flags |= IFF_NOFILTER;
1945 
1946                 if (copy_to_user(argp, &ifr, ifreq_len))
1947                         ret = -EFAULT;
1948                 break;
1949 
1950         case TUNSETNOCSUM:
1951                 /* Disable/Enable checksum */
1952 
1953                 /* [unimplemented] */
1954                 tun_debug(KERN_INFO, tun, "ignored: set checksum %s\n",
1955                           arg ? "disabled" : "enabled");
1956                 break;
1957 
1958         case TUNSETPERSIST:
1959                 /* Disable/Enable persist mode. Keep an extra reference to the
1960                  * module to prevent the module being unprobed.
1961                  */
1962                 if (arg && !(tun->flags & TUN_PERSIST)) {
1963                         tun->flags |= TUN_PERSIST;
1964                         __module_get(THIS_MODULE);
1965                 }
1966                 if (!arg && (tun->flags & TUN_PERSIST)) {
1967                         tun->flags &= ~TUN_PERSIST;
1968                         module_put(THIS_MODULE);
1969                 }
1970 
1971                 tun_debug(KERN_INFO, tun, "persist %s\n",
1972                           arg ? "enabled" : "disabled");
1973                 break;
1974 
1975         case TUNSETOWNER:
1976                 /* Set owner of the device */
1977                 owner = make_kuid(current_user_ns(), arg);
1978                 if (!uid_valid(owner)) {
1979                         ret = -EINVAL;
1980                         break;
1981                 }
1982                 tun->owner = owner;
1983                 tun_debug(KERN_INFO, tun, "owner set to %u\n",
1984                           from_kuid(&init_user_ns, tun->owner));
1985                 break;
1986 
1987         case TUNSETGROUP:
1988                 /* Set group of the device */
1989                 group = make_kgid(current_user_ns(), arg);
1990                 if (!gid_valid(group)) {
1991                         ret = -EINVAL;
1992                         break;
1993                 }
1994                 tun->group = group;
1995                 tun_debug(KERN_INFO, tun, "group set to %u\n",
1996                           from_kgid(&init_user_ns, tun->group));
1997                 break;
1998 
1999         case TUNSETLINK:
2000                 /* Only allow setting the type when the interface is down */
2001                 if (tun->dev->flags & IFF_UP) {
2002                         tun_debug(KERN_INFO, tun,
2003                                   "Linktype set failed because interface is up\n");
2004                         ret = -EBUSY;
2005                 } else {
2006                         tun->dev->type = (int) arg;
2007                         tun_debug(KERN_INFO, tun, "linktype set to %d\n",
2008                                   tun->dev->type);
2009                         ret = 0;
2010                 }
2011                 break;
2012 
2013 #ifdef TUN_DEBUG
2014         case TUNSETDEBUG:
2015                 tun->debug = arg;
2016                 break;
2017 #endif
2018         case TUNSETOFFLOAD:
2019                 ret = set_offload(tun, arg);
2020                 break;
2021 
2022         case TUNSETTXFILTER:
2023                 /* Can be set only for TAPs */
2024                 ret = -EINVAL;
2025                 if ((tun->flags & TUN_TYPE_MASK) != TUN_TAP_DEV)
2026                         break;
2027                 ret = update_filter(&tun->txflt, (void __user *)arg);
2028                 break;
2029 
2030         case SIOCGIFHWADDR:
2031                 /* Get hw address */
2032                 memcpy(ifr.ifr_hwaddr.sa_data, tun->dev->dev_addr, ETH_ALEN);
2033                 ifr.ifr_hwaddr.sa_family = tun->dev->type;
2034                 if (copy_to_user(argp, &ifr, ifreq_len))
2035                         ret = -EFAULT;
2036                 break;
2037 
2038         case SIOCSIFHWADDR:
2039                 /* Set hw address */
2040                 tun_debug(KERN_DEBUG, tun, "set hw address: %pM\n",
2041                           ifr.ifr_hwaddr.sa_data);
2042 
2043                 ret = dev_set_mac_address(tun->dev, &ifr.ifr_hwaddr);
2044                 break;
2045 
2046         case TUNGETSNDBUF:
2047                 sndbuf = tfile->socket.sk->sk_sndbuf;
2048                 if (copy_to_user(argp, &sndbuf, sizeof(sndbuf)))
2049                         ret = -EFAULT;
2050                 break;
2051 
2052         case TUNSETSNDBUF:
2053                 if (copy_from_user(&sndbuf, argp, sizeof(sndbuf))) {
2054                         ret = -EFAULT;
2055                         break;
2056                 }
2057 
2058                 tun->sndbuf = sndbuf;
2059                 tun_set_sndbuf(tun);
2060                 break;
2061 
2062         case TUNGETVNETHDRSZ:
2063                 vnet_hdr_sz = tun->vnet_hdr_sz;
2064                 if (copy_to_user(argp, &vnet_hdr_sz, sizeof(vnet_hdr_sz)))
2065                         ret = -EFAULT;
2066                 break;
2067 
2068         case TUNSETVNETHDRSZ:
2069                 if (copy_from_user(&vnet_hdr_sz, argp, sizeof(vnet_hdr_sz))) {
2070                         ret = -EFAULT;
2071                         break;
2072                 }
2073                 if (vnet_hdr_sz < (int)sizeof(struct virtio_net_hdr)) {
2074                         ret = -EINVAL;
2075                         break;
2076                 }
2077 
2078                 tun->vnet_hdr_sz = vnet_hdr_sz;
2079                 break;
2080 
2081         case TUNATTACHFILTER:
2082                 /* Can be set only for TAPs */
2083                 ret = -EINVAL;
2084                 if ((tun->flags & TUN_TYPE_MASK) != TUN_TAP_DEV)
2085                         break;
2086                 ret = -EFAULT;
2087                 if (copy_from_user(&tun->fprog, argp, sizeof(tun->fprog)))
2088                         break;
2089 
2090                 ret = tun_attach_filter(tun);
2091                 break;
2092 
2093         case TUNDETACHFILTER:
2094                 /* Can be set only for TAPs */
2095                 ret = -EINVAL;
2096                 if ((tun->flags & TUN_TYPE_MASK) != TUN_TAP_DEV)
2097                         break;
2098                 ret = 0;
2099                 tun_detach_filter(tun, tun->numqueues);
2100                 break;
2101 
2102         case TUNGETFILTER:
2103                 ret = -EINVAL;
2104                 if ((tun->flags & TUN_TYPE_MASK) != TUN_TAP_DEV)
2105                         break;
2106                 ret = -EFAULT;
2107                 if (copy_to_user(argp, &tun->fprog, sizeof(tun->fprog)))
2108                         break;
2109                 ret = 0;
2110                 break;
2111 
2112         default:
2113                 ret = -EINVAL;
2114                 break;
2115         }
2116 
2117 unlock:
2118         rtnl_unlock();
2119         if (tun)
2120                 tun_put(tun);
2121         return ret;
2122 }
2123 
2124 static long tun_chr_ioctl(struct file *file,
2125                           unsigned int cmd, unsigned long arg)
2126 {
2127         return __tun_chr_ioctl(file, cmd, arg, sizeof (struct ifreq));
2128 }
2129 
2130 #ifdef CONFIG_COMPAT
2131 static long tun_chr_compat_ioctl(struct file *file,
2132                          unsigned int cmd, unsigned long arg)
2133 {
2134         switch (cmd) {
2135         case TUNSETIFF:
2136         case TUNGETIFF:
2137         case TUNSETTXFILTER:
2138         case TUNGETSNDBUF:
2139         case TUNSETSNDBUF:
2140         case SIOCGIFHWADDR:
2141         case SIOCSIFHWADDR:
2142                 arg = (unsigned long)compat_ptr(arg);
2143                 break;
2144         default:
2145                 arg = (compat_ulong_t)arg;
2146                 break;
2147         }
2148 
2149         /*
2150          * compat_ifreq is shorter than ifreq, so we must not access beyond
2151          * the end of that structure. All fields that are used in this
2152          * driver are compatible though, we don't need to convert the
2153          * contents.
2154          */
2155         return __tun_chr_ioctl(file, cmd, arg, sizeof(struct compat_ifreq));
2156 }
2157 #endif /* CONFIG_COMPAT */
2158 
2159 static int tun_chr_fasync(int fd, struct file *file, int on)
2160 {
2161         struct tun_file *tfile = file->private_data;
2162         int ret;
2163 
2164         if ((ret = fasync_helper(fd, file, on, &tfile->fasync)) < 0)
2165                 goto out;
2166 
2167         if (on) {
2168                 __f_setown(file, task_pid(current), PIDTYPE_PID, 0);
2169                 tfile->flags |= TUN_FASYNC;
2170         } else
2171                 tfile->flags &= ~TUN_FASYNC;
2172         ret = 0;
2173 out:
2174         return ret;
2175 }
2176 
2177 static int tun_chr_open(struct inode *inode, struct file * file)
2178 {
2179         struct tun_file *tfile;
2180 
2181         DBG1(KERN_INFO, "tunX: tun_chr_open\n");
2182 
2183         tfile = (struct tun_file *)sk_alloc(&init_net, AF_UNSPEC, GFP_KERNEL,
2184                                             &tun_proto);
2185         if (!tfile)
2186                 return -ENOMEM;
2187         RCU_INIT_POINTER(tfile->tun, NULL);
2188         tfile->net = get_net(current->nsproxy->net_ns);
2189         tfile->flags = 0;
2190         tfile->ifindex = 0;
2191 
2192         init_waitqueue_head(&tfile->wq.wait);
2193         RCU_INIT_POINTER(tfile->socket.wq, &tfile->wq);
2194 
2195         tfile->socket.file = file;
2196         tfile->socket.ops = &tun_socket_ops;
2197 
2198         sock_init_data(&tfile->socket, &tfile->sk);
2199         sk_change_net(&tfile->sk, tfile->net);
2200 
2201         tfile->sk.sk_write_space = tun_sock_write_space;
2202         tfile->sk.sk_sndbuf = INT_MAX;
2203 
2204         file->private_data = tfile;
2205         set_bit(SOCK_EXTERNALLY_ALLOCATED, &tfile->socket.flags);
2206         INIT_LIST_HEAD(&tfile->next);
2207 
2208         sock_set_flag(&tfile->sk, SOCK_ZEROCOPY);
2209 
2210         return 0;
2211 }
2212 
2213 static int tun_chr_close(struct inode *inode, struct file *file)
2214 {
2215         struct tun_file *tfile = file->private_data;
2216         struct net *net = tfile->net;
2217 
2218         tun_detach(tfile, true);
2219         put_net(net);
2220 
2221         return 0;
2222 }
2223 
2224 #ifdef CONFIG_PROC_FS
2225 static int tun_chr_show_fdinfo(struct seq_file *m, struct file *f)
2226 {
2227         struct tun_struct *tun;
2228         struct ifreq ifr;
2229 
2230         memset(&ifr, 0, sizeof(ifr));
2231 
2232         rtnl_lock();
2233         tun = tun_get(f);
2234         if (tun)
2235                 tun_get_iff(current->nsproxy->net_ns, tun, &ifr);
2236         rtnl_unlock();
2237 
2238         if (tun)
2239                 tun_put(tun);
2240 
2241         return seq_printf(m, "iff:\t%s\n", ifr.ifr_name);
2242 }
2243 #endif
2244 
2245 static const struct file_operations tun_fops = {
2246         .owner  = THIS_MODULE,
2247         .llseek = no_llseek,
2248         .read  = do_sync_read,
2249         .aio_read  = tun_chr_aio_read,
2250         .write = do_sync_write,
2251         .aio_write = tun_chr_aio_write,
2252         .poll   = tun_chr_poll,
2253         .unlocked_ioctl = tun_chr_ioctl,
2254 #ifdef CONFIG_COMPAT
2255         .compat_ioctl = tun_chr_compat_ioctl,
2256 #endif
2257         .open   = tun_chr_open,
2258         .release = tun_chr_close,
2259         .fasync = tun_chr_fasync,
2260 #ifdef CONFIG_PROC_FS
2261         .show_fdinfo = tun_chr_show_fdinfo,
2262 #endif
2263 };
2264 
2265 static struct miscdevice tun_miscdev = {
2266         .minor = TUN_MINOR,
2267         .name = "tun",
2268         .nodename = "net/tun",
2269         .fops = &tun_fops,
2270 };
2271 
2272 /* ethtool interface */
2273 
2274 static int tun_get_settings(struct net_device *dev, struct ethtool_cmd *cmd)
2275 {
2276         cmd->supported          = 0;
2277         cmd->advertising        = 0;
2278         ethtool_cmd_speed_set(cmd, SPEED_10);
2279         cmd->duplex             = DUPLEX_FULL;
2280         cmd->port               = PORT_TP;
2281         cmd->phy_address        = 0;
2282         cmd->transceiver        = XCVR_INTERNAL;
2283         cmd->autoneg            = AUTONEG_DISABLE;
2284         cmd->maxtxpkt           = 0;
2285         cmd->maxrxpkt           = 0;
2286         return 0;
2287 }
2288 
2289 static void tun_get_drvinfo(struct net_device *dev, struct ethtool_drvinfo *info)
2290 {
2291         struct tun_struct *tun = netdev_priv(dev);
2292 
2293         strlcpy(info->driver, DRV_NAME, sizeof(info->driver));
2294         strlcpy(info->version, DRV_VERSION, sizeof(info->version));
2295 
2296         switch (tun->flags & TUN_TYPE_MASK) {
2297         case TUN_TUN_DEV:
2298                 strlcpy(info->bus_info, "tun", sizeof(info->bus_info));
2299                 break;
2300         case TUN_TAP_DEV:
2301                 strlcpy(info->bus_info, "tap", sizeof(info->bus_info));
2302                 break;
2303         }
2304 }
2305 
2306 static u32 tun_get_msglevel(struct net_device *dev)
2307 {
2308 #ifdef TUN_DEBUG
2309         struct tun_struct *tun = netdev_priv(dev);
2310         return tun->debug;
2311 #else
2312         return -EOPNOTSUPP;
2313 #endif
2314 }
2315 
2316 static void tun_set_msglevel(struct net_device *dev, u32 value)
2317 {
2318 #ifdef TUN_DEBUG
2319         struct tun_struct *tun = netdev_priv(dev);
2320         tun->debug = value;
2321 #endif
2322 }
2323 
2324 static const struct ethtool_ops tun_ethtool_ops = {
2325         .get_settings   = tun_get_settings,
2326         .get_drvinfo    = tun_get_drvinfo,
2327         .get_msglevel   = tun_get_msglevel,
2328         .set_msglevel   = tun_set_msglevel,
2329         .get_link       = ethtool_op_get_link,
2330         .get_ts_info    = ethtool_op_get_ts_info,
2331 };
2332 
2333 
2334 static int __init tun_init(void)
2335 {
2336         int ret = 0;
2337 
2338         pr_info("%s, %s\n", DRV_DESCRIPTION, DRV_VERSION);
2339         pr_info("%s\n", DRV_COPYRIGHT);
2340 
2341         ret = rtnl_link_register(&tun_link_ops);
2342         if (ret) {
2343                 pr_err("Can't register link_ops\n");
2344                 goto err_linkops;
2345         }
2346 
2347         ret = misc_register(&tun_miscdev);
2348         if (ret) {
2349                 pr_err("Can't register misc device %d\n", TUN_MINOR);
2350                 goto err_misc;
2351         }
2352         return  0;
2353 err_misc:
2354         rtnl_link_unregister(&tun_link_ops);
2355 err_linkops:
2356         return ret;
2357 }
2358 
2359 static void tun_cleanup(void)
2360 {
2361         misc_deregister(&tun_miscdev);
2362         rtnl_link_unregister(&tun_link_ops);
2363 }
2364 
2365 /* Get an underlying socket object from tun file.  Returns error unless file is
2366  * attached to a device.  The returned object works like a packet socket, it
2367  * can be used for sock_sendmsg/sock_recvmsg.  The caller is responsible for
2368  * holding a reference to the file for as long as the socket is in use. */
2369 struct socket *tun_get_socket(struct file *file)
2370 {
2371         struct tun_file *tfile;
2372         if (file->f_op != &tun_fops)
2373                 return ERR_PTR(-EINVAL);
2374         tfile = file->private_data;
2375         if (!tfile)
2376                 return ERR_PTR(-EBADFD);
2377         return &tfile->socket;
2378 }
2379 EXPORT_SYMBOL_GPL(tun_get_socket);
2380 
2381 module_init(tun_init);
2382 module_exit(tun_cleanup);
2383 MODULE_DESCRIPTION(DRV_DESCRIPTION);
2384 MODULE_AUTHOR(DRV_COPYRIGHT);
2385 MODULE_LICENSE("GPL");
2386 MODULE_ALIAS_MISCDEV(TUN_MINOR);
2387 MODULE_ALIAS("devname:net/tun");
2388 

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