1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/etherdevice.h>
3 #include <linux/if_tap.h>
4 #include <linux/if_vlan.h>
5 #include <linux/interrupt.h>
6 #include <linux/nsproxy.h>
7 #include <linux/compat.h>
8 #include <linux/if_tun.h>
9 #include <linux/module.h>
10 #include <linux/skbuff.h>
11 #include <linux/cache.h>
12 #include <linux/sched/signal.h>
13 #include <linux/types.h>
14 #include <linux/slab.h>
15 #include <linux/wait.h>
16 #include <linux/cdev.h>
17 #include <linux/idr.h>
18 #include <linux/fs.h>
19 #include <linux/uio.h>
20
21 #include <net/gso.h>
22 #include <net/net_namespace.h>
23 #include <net/rtnetlink.h>
24 #include <net/sock.h>
25 #include <net/xdp.h>
26 #include <linux/virtio_net.h>
27 #include <linux/skb_array.h>
28
29 #define TAP_IFFEATURES (IFF_VNET_HDR | IFF_MULTI_QUEUE)
30
31 #define TAP_VNET_LE 0x80000000
32 #define TAP_VNET_BE 0x40000000
33
34 #ifdef CONFIG_TUN_VNET_CROSS_LE
tap_legacy_is_little_endian(struct tap_queue * q)35 static inline bool tap_legacy_is_little_endian(struct tap_queue *q)
36 {
37 return q->flags & TAP_VNET_BE ? false :
38 virtio_legacy_is_little_endian();
39 }
40
tap_get_vnet_be(struct tap_queue * q,int __user * sp)41 static long tap_get_vnet_be(struct tap_queue *q, int __user *sp)
42 {
43 int s = !!(q->flags & TAP_VNET_BE);
44
45 if (put_user(s, sp))
46 return -EFAULT;
47
48 return 0;
49 }
50
tap_set_vnet_be(struct tap_queue * q,int __user * sp)51 static long tap_set_vnet_be(struct tap_queue *q, int __user *sp)
52 {
53 int s;
54
55 if (get_user(s, sp))
56 return -EFAULT;
57
58 if (s)
59 q->flags |= TAP_VNET_BE;
60 else
61 q->flags &= ~TAP_VNET_BE;
62
63 return 0;
64 }
65 #else
tap_legacy_is_little_endian(struct tap_queue * q)66 static inline bool tap_legacy_is_little_endian(struct tap_queue *q)
67 {
68 return virtio_legacy_is_little_endian();
69 }
70
tap_get_vnet_be(struct tap_queue * q,int __user * argp)71 static long tap_get_vnet_be(struct tap_queue *q, int __user *argp)
72 {
73 return -EINVAL;
74 }
75
tap_set_vnet_be(struct tap_queue * q,int __user * argp)76 static long tap_set_vnet_be(struct tap_queue *q, int __user *argp)
77 {
78 return -EINVAL;
79 }
80 #endif /* CONFIG_TUN_VNET_CROSS_LE */
81
tap_is_little_endian(struct tap_queue * q)82 static inline bool tap_is_little_endian(struct tap_queue *q)
83 {
84 return q->flags & TAP_VNET_LE ||
85 tap_legacy_is_little_endian(q);
86 }
87
tap16_to_cpu(struct tap_queue * q,__virtio16 val)88 static inline u16 tap16_to_cpu(struct tap_queue *q, __virtio16 val)
89 {
90 return __virtio16_to_cpu(tap_is_little_endian(q), val);
91 }
92
cpu_to_tap16(struct tap_queue * q,u16 val)93 static inline __virtio16 cpu_to_tap16(struct tap_queue *q, u16 val)
94 {
95 return __cpu_to_virtio16(tap_is_little_endian(q), val);
96 }
97
98 static struct proto tap_proto = {
99 .name = "tap",
100 .owner = THIS_MODULE,
101 .obj_size = sizeof(struct tap_queue),
102 };
103
104 #define TAP_NUM_DEVS (1U << MINORBITS)
105
106 static LIST_HEAD(major_list);
107
108 struct major_info {
109 struct rcu_head rcu;
110 dev_t major;
111 struct idr minor_idr;
112 spinlock_t minor_lock;
113 const char *device_name;
114 struct list_head next;
115 };
116
117 #define GOODCOPY_LEN 128
118
119 static const struct proto_ops tap_socket_ops;
120
121 #define RX_OFFLOADS (NETIF_F_GRO | NETIF_F_LRO)
122 #define TAP_FEATURES (NETIF_F_GSO | NETIF_F_SG | NETIF_F_FRAGLIST)
123
tap_dev_get_rcu(const struct net_device * dev)124 static struct tap_dev *tap_dev_get_rcu(const struct net_device *dev)
125 {
126 return rcu_dereference(dev->rx_handler_data);
127 }
128
129 /*
130 * RCU usage:
131 * The tap_queue and the macvlan_dev are loosely coupled, the
132 * pointers from one to the other can only be read while rcu_read_lock
133 * or rtnl is held.
134 *
135 * Both the file and the macvlan_dev hold a reference on the tap_queue
136 * through sock_hold(&q->sk). When the macvlan_dev goes away first,
137 * q->vlan becomes inaccessible. When the files gets closed,
138 * tap_get_queue() fails.
139 *
140 * There may still be references to the struct sock inside of the
141 * queue from outbound SKBs, but these never reference back to the
142 * file or the dev. The data structure is freed through __sk_free
143 * when both our references and any pending SKBs are gone.
144 */
145
tap_enable_queue(struct tap_dev * tap,struct file * file,struct tap_queue * q)146 static int tap_enable_queue(struct tap_dev *tap, struct file *file,
147 struct tap_queue *q)
148 {
149 int err = -EINVAL;
150
151 ASSERT_RTNL();
152
153 if (q->enabled)
154 goto out;
155
156 err = 0;
157 rcu_assign_pointer(tap->taps[tap->numvtaps], q);
158 q->queue_index = tap->numvtaps;
159 q->enabled = true;
160
161 tap->numvtaps++;
162 out:
163 return err;
164 }
165
166 /* Requires RTNL */
tap_set_queue(struct tap_dev * tap,struct file * file,struct tap_queue * q)167 static int tap_set_queue(struct tap_dev *tap, struct file *file,
168 struct tap_queue *q)
169 {
170 if (tap->numqueues == MAX_TAP_QUEUES)
171 return -EBUSY;
172
173 rcu_assign_pointer(q->tap, tap);
174 rcu_assign_pointer(tap->taps[tap->numvtaps], q);
175 sock_hold(&q->sk);
176
177 q->file = file;
178 q->queue_index = tap->numvtaps;
179 q->enabled = true;
180 file->private_data = q;
181 list_add_tail(&q->next, &tap->queue_list);
182
183 tap->numvtaps++;
184 tap->numqueues++;
185
186 return 0;
187 }
188
tap_disable_queue(struct tap_queue * q)189 static int tap_disable_queue(struct tap_queue *q)
190 {
191 struct tap_dev *tap;
192 struct tap_queue *nq;
193
194 ASSERT_RTNL();
195 if (!q->enabled)
196 return -EINVAL;
197
198 tap = rtnl_dereference(q->tap);
199
200 if (tap) {
201 int index = q->queue_index;
202 BUG_ON(index >= tap->numvtaps);
203 nq = rtnl_dereference(tap->taps[tap->numvtaps - 1]);
204 nq->queue_index = index;
205
206 rcu_assign_pointer(tap->taps[index], nq);
207 RCU_INIT_POINTER(tap->taps[tap->numvtaps - 1], NULL);
208 q->enabled = false;
209
210 tap->numvtaps--;
211 }
212
213 return 0;
214 }
215
216 /*
217 * The file owning the queue got closed, give up both
218 * the reference that the files holds as well as the
219 * one from the macvlan_dev if that still exists.
220 *
221 * Using the spinlock makes sure that we don't get
222 * to the queue again after destroying it.
223 */
tap_put_queue(struct tap_queue * q)224 static void tap_put_queue(struct tap_queue *q)
225 {
226 struct tap_dev *tap;
227
228 rtnl_lock();
229 tap = rtnl_dereference(q->tap);
230
231 if (tap) {
232 if (q->enabled)
233 BUG_ON(tap_disable_queue(q));
234
235 tap->numqueues--;
236 RCU_INIT_POINTER(q->tap, NULL);
237 sock_put(&q->sk);
238 list_del_init(&q->next);
239 }
240
241 rtnl_unlock();
242
243 synchronize_rcu();
244 sock_put(&q->sk);
245 }
246
247 /*
248 * Select a queue based on the rxq of the device on which this packet
249 * arrived. If the incoming device is not mq, calculate a flow hash
250 * to select a queue. If all fails, find the first available queue.
251 * Cache vlan->numvtaps since it can become zero during the execution
252 * of this function.
253 */
tap_get_queue(struct tap_dev * tap,struct sk_buff * skb)254 static struct tap_queue *tap_get_queue(struct tap_dev *tap,
255 struct sk_buff *skb)
256 {
257 struct tap_queue *queue = NULL;
258 /* Access to taps array is protected by rcu, but access to numvtaps
259 * isn't. Below we use it to lookup a queue, but treat it as a hint
260 * and validate that the result isn't NULL - in case we are
261 * racing against queue removal.
262 */
263 int numvtaps = READ_ONCE(tap->numvtaps);
264 __u32 rxq;
265
266 if (!numvtaps)
267 goto out;
268
269 if (numvtaps == 1)
270 goto single;
271
272 /* Check if we can use flow to select a queue */
273 rxq = skb_get_hash(skb);
274 if (rxq) {
275 queue = rcu_dereference(tap->taps[rxq % numvtaps]);
276 goto out;
277 }
278
279 if (likely(skb_rx_queue_recorded(skb))) {
280 rxq = skb_get_rx_queue(skb);
281
282 while (unlikely(rxq >= numvtaps))
283 rxq -= numvtaps;
284
285 queue = rcu_dereference(tap->taps[rxq]);
286 goto out;
287 }
288
289 single:
290 queue = rcu_dereference(tap->taps[0]);
291 out:
292 return queue;
293 }
294
295 /*
296 * The net_device is going away, give up the reference
297 * that it holds on all queues and safely set the pointer
298 * from the queues to NULL.
299 */
tap_del_queues(struct tap_dev * tap)300 void tap_del_queues(struct tap_dev *tap)
301 {
302 struct tap_queue *q, *tmp;
303
304 ASSERT_RTNL();
305 list_for_each_entry_safe(q, tmp, &tap->queue_list, next) {
306 list_del_init(&q->next);
307 RCU_INIT_POINTER(q->tap, NULL);
308 if (q->enabled)
309 tap->numvtaps--;
310 tap->numqueues--;
311 sock_put(&q->sk);
312 }
313 BUG_ON(tap->numvtaps);
314 BUG_ON(tap->numqueues);
315 /* guarantee that any future tap_set_queue will fail */
316 tap->numvtaps = MAX_TAP_QUEUES;
317 }
318 EXPORT_SYMBOL_GPL(tap_del_queues);
319
tap_handle_frame(struct sk_buff ** pskb)320 rx_handler_result_t tap_handle_frame(struct sk_buff **pskb)
321 {
322 struct sk_buff *skb = *pskb;
323 struct net_device *dev = skb->dev;
324 struct tap_dev *tap;
325 struct tap_queue *q;
326 netdev_features_t features = TAP_FEATURES;
327 enum skb_drop_reason drop_reason;
328
329 tap = tap_dev_get_rcu(dev);
330 if (!tap)
331 return RX_HANDLER_PASS;
332
333 q = tap_get_queue(tap, skb);
334 if (!q)
335 return RX_HANDLER_PASS;
336
337 skb_push(skb, ETH_HLEN);
338
339 /* Apply the forward feature mask so that we perform segmentation
340 * according to users wishes. This only works if VNET_HDR is
341 * enabled.
342 */
343 if (q->flags & IFF_VNET_HDR)
344 features |= tap->tap_features;
345 if (netif_needs_gso(skb, features)) {
346 struct sk_buff *segs = __skb_gso_segment(skb, features, false);
347 struct sk_buff *next;
348
349 if (IS_ERR(segs)) {
350 drop_reason = SKB_DROP_REASON_SKB_GSO_SEG;
351 goto drop;
352 }
353
354 if (!segs) {
355 if (ptr_ring_produce(&q->ring, skb)) {
356 drop_reason = SKB_DROP_REASON_FULL_RING;
357 goto drop;
358 }
359 goto wake_up;
360 }
361
362 consume_skb(skb);
363 skb_list_walk_safe(segs, skb, next) {
364 skb_mark_not_on_list(skb);
365 if (ptr_ring_produce(&q->ring, skb)) {
366 drop_reason = SKB_DROP_REASON_FULL_RING;
367 kfree_skb_reason(skb, drop_reason);
368 kfree_skb_list_reason(next, drop_reason);
369 break;
370 }
371 }
372 } else {
373 /* If we receive a partial checksum and the tap side
374 * doesn't support checksum offload, compute the checksum.
375 * Note: it doesn't matter which checksum feature to
376 * check, we either support them all or none.
377 */
378 if (skb->ip_summed == CHECKSUM_PARTIAL &&
379 !(features & NETIF_F_CSUM_MASK) &&
380 skb_checksum_help(skb)) {
381 drop_reason = SKB_DROP_REASON_SKB_CSUM;
382 goto drop;
383 }
384 if (ptr_ring_produce(&q->ring, skb)) {
385 drop_reason = SKB_DROP_REASON_FULL_RING;
386 goto drop;
387 }
388 }
389
390 wake_up:
391 wake_up_interruptible_poll(sk_sleep(&q->sk), EPOLLIN | EPOLLRDNORM | EPOLLRDBAND);
392 return RX_HANDLER_CONSUMED;
393
394 drop:
395 /* Count errors/drops only here, thus don't care about args. */
396 if (tap->count_rx_dropped)
397 tap->count_rx_dropped(tap);
398 kfree_skb_reason(skb, drop_reason);
399 return RX_HANDLER_CONSUMED;
400 }
401 EXPORT_SYMBOL_GPL(tap_handle_frame);
402
tap_get_major(int major)403 static struct major_info *tap_get_major(int major)
404 {
405 struct major_info *tap_major;
406
407 list_for_each_entry_rcu(tap_major, &major_list, next) {
408 if (tap_major->major == major)
409 return tap_major;
410 }
411
412 return NULL;
413 }
414
tap_get_minor(dev_t major,struct tap_dev * tap)415 int tap_get_minor(dev_t major, struct tap_dev *tap)
416 {
417 int retval = -ENOMEM;
418 struct major_info *tap_major;
419
420 rcu_read_lock();
421 tap_major = tap_get_major(MAJOR(major));
422 if (!tap_major) {
423 retval = -EINVAL;
424 goto unlock;
425 }
426
427 spin_lock(&tap_major->minor_lock);
428 retval = idr_alloc(&tap_major->minor_idr, tap, 1, TAP_NUM_DEVS, GFP_ATOMIC);
429 if (retval >= 0) {
430 tap->minor = retval;
431 } else if (retval == -ENOSPC) {
432 netdev_err(tap->dev, "Too many tap devices\n");
433 retval = -EINVAL;
434 }
435 spin_unlock(&tap_major->minor_lock);
436
437 unlock:
438 rcu_read_unlock();
439 return retval < 0 ? retval : 0;
440 }
441 EXPORT_SYMBOL_GPL(tap_get_minor);
442
tap_free_minor(dev_t major,struct tap_dev * tap)443 void tap_free_minor(dev_t major, struct tap_dev *tap)
444 {
445 struct major_info *tap_major;
446
447 rcu_read_lock();
448 tap_major = tap_get_major(MAJOR(major));
449 if (!tap_major) {
450 goto unlock;
451 }
452
453 spin_lock(&tap_major->minor_lock);
454 if (tap->minor) {
455 idr_remove(&tap_major->minor_idr, tap->minor);
456 tap->minor = 0;
457 }
458 spin_unlock(&tap_major->minor_lock);
459
460 unlock:
461 rcu_read_unlock();
462 }
463 EXPORT_SYMBOL_GPL(tap_free_minor);
464
dev_get_by_tap_file(int major,int minor)465 static struct tap_dev *dev_get_by_tap_file(int major, int minor)
466 {
467 struct net_device *dev = NULL;
468 struct tap_dev *tap;
469 struct major_info *tap_major;
470
471 rcu_read_lock();
472 tap_major = tap_get_major(major);
473 if (!tap_major) {
474 tap = NULL;
475 goto unlock;
476 }
477
478 spin_lock(&tap_major->minor_lock);
479 tap = idr_find(&tap_major->minor_idr, minor);
480 if (tap) {
481 dev = tap->dev;
482 dev_hold(dev);
483 }
484 spin_unlock(&tap_major->minor_lock);
485
486 unlock:
487 rcu_read_unlock();
488 return tap;
489 }
490
tap_sock_write_space(struct sock * sk)491 static void tap_sock_write_space(struct sock *sk)
492 {
493 wait_queue_head_t *wqueue;
494
495 if (!sock_writeable(sk) ||
496 !test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags))
497 return;
498
499 wqueue = sk_sleep(sk);
500 if (wqueue && waitqueue_active(wqueue))
501 wake_up_interruptible_poll(wqueue, EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND);
502 }
503
tap_sock_destruct(struct sock * sk)504 static void tap_sock_destruct(struct sock *sk)
505 {
506 struct tap_queue *q = container_of(sk, struct tap_queue, sk);
507
508 ptr_ring_cleanup(&q->ring, __skb_array_destroy_skb);
509 }
510
tap_open(struct inode * inode,struct file * file)511 static int tap_open(struct inode *inode, struct file *file)
512 {
513 struct net *net = current->nsproxy->net_ns;
514 struct tap_dev *tap;
515 struct tap_queue *q;
516 int err = -ENODEV;
517
518 rtnl_lock();
519 tap = dev_get_by_tap_file(imajor(inode), iminor(inode));
520 if (!tap)
521 goto err;
522
523 err = -ENOMEM;
524 q = (struct tap_queue *)sk_alloc(net, AF_UNSPEC, GFP_KERNEL,
525 &tap_proto, 0);
526 if (!q)
527 goto err;
528 if (ptr_ring_init(&q->ring, tap->dev->tx_queue_len, GFP_KERNEL)) {
529 sk_free(&q->sk);
530 goto err;
531 }
532
533 init_waitqueue_head(&q->sock.wq.wait);
534 q->sock.type = SOCK_RAW;
535 q->sock.state = SS_CONNECTED;
536 q->sock.file = file;
537 q->sock.ops = &tap_socket_ops;
538 sock_init_data_uid(&q->sock, &q->sk, current_fsuid());
539 q->sk.sk_write_space = tap_sock_write_space;
540 q->sk.sk_destruct = tap_sock_destruct;
541 q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP;
542 q->vnet_hdr_sz = sizeof(struct virtio_net_hdr);
543
544 /*
545 * so far only KVM virtio_net uses tap, enable zero copy between
546 * guest kernel and host kernel when lower device supports zerocopy
547 *
548 * The macvlan supports zerocopy iff the lower device supports zero
549 * copy so we don't have to look at the lower device directly.
550 */
551 if ((tap->dev->features & NETIF_F_HIGHDMA) && (tap->dev->features & NETIF_F_SG))
552 sock_set_flag(&q->sk, SOCK_ZEROCOPY);
553
554 err = tap_set_queue(tap, file, q);
555 if (err) {
556 /* tap_sock_destruct() will take care of freeing ptr_ring */
557 goto err_put;
558 }
559
560 /* tap groks IOCB_NOWAIT just fine, mark it as such */
561 file->f_mode |= FMODE_NOWAIT;
562
563 dev_put(tap->dev);
564
565 rtnl_unlock();
566 return err;
567
568 err_put:
569 sock_put(&q->sk);
570 err:
571 if (tap)
572 dev_put(tap->dev);
573
574 rtnl_unlock();
575 return err;
576 }
577
tap_release(struct inode * inode,struct file * file)578 static int tap_release(struct inode *inode, struct file *file)
579 {
580 struct tap_queue *q = file->private_data;
581 tap_put_queue(q);
582 return 0;
583 }
584
tap_poll(struct file * file,poll_table * wait)585 static __poll_t tap_poll(struct file *file, poll_table *wait)
586 {
587 struct tap_queue *q = file->private_data;
588 __poll_t mask = EPOLLERR;
589
590 if (!q)
591 goto out;
592
593 mask = 0;
594 poll_wait(file, &q->sock.wq.wait, wait);
595
596 if (!ptr_ring_empty(&q->ring))
597 mask |= EPOLLIN | EPOLLRDNORM;
598
599 if (sock_writeable(&q->sk) ||
600 (!test_and_set_bit(SOCKWQ_ASYNC_NOSPACE, &q->sock.flags) &&
601 sock_writeable(&q->sk)))
602 mask |= EPOLLOUT | EPOLLWRNORM;
603
604 out:
605 return mask;
606 }
607
tap_alloc_skb(struct sock * sk,size_t prepad,size_t len,size_t linear,int noblock,int * err)608 static inline struct sk_buff *tap_alloc_skb(struct sock *sk, size_t prepad,
609 size_t len, size_t linear,
610 int noblock, int *err)
611 {
612 struct sk_buff *skb;
613
614 /* Under a page? Don't bother with paged skb. */
615 if (prepad + len < PAGE_SIZE || !linear)
616 linear = len;
617
618 if (len - linear > MAX_SKB_FRAGS * (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER))
619 linear = len - MAX_SKB_FRAGS * (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER);
620 skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
621 err, PAGE_ALLOC_COSTLY_ORDER);
622 if (!skb)
623 return NULL;
624
625 skb_reserve(skb, prepad);
626 skb_put(skb, linear);
627 skb->data_len = len - linear;
628 skb->len += len - linear;
629
630 return skb;
631 }
632
633 /* Neighbour code has some assumptions on HH_DATA_MOD alignment */
634 #define TAP_RESERVE HH_DATA_OFF(ETH_HLEN)
635
636 /* Get packet from user space buffer */
tap_get_user(struct tap_queue * q,void * msg_control,struct iov_iter * from,int noblock)637 static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,
638 struct iov_iter *from, int noblock)
639 {
640 int good_linear = SKB_MAX_HEAD(TAP_RESERVE);
641 struct sk_buff *skb;
642 struct tap_dev *tap;
643 unsigned long total_len = iov_iter_count(from);
644 unsigned long len = total_len;
645 int err;
646 struct virtio_net_hdr vnet_hdr = { 0 };
647 int vnet_hdr_len = 0;
648 int copylen = 0;
649 int depth;
650 bool zerocopy = false;
651 size_t linear;
652 enum skb_drop_reason drop_reason;
653
654 if (q->flags & IFF_VNET_HDR) {
655 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
656
657 err = -EINVAL;
658 if (len < vnet_hdr_len)
659 goto err;
660 len -= vnet_hdr_len;
661
662 err = -EFAULT;
663 if (!copy_from_iter_full(&vnet_hdr, sizeof(vnet_hdr), from))
664 goto err;
665 iov_iter_advance(from, vnet_hdr_len - sizeof(vnet_hdr));
666 if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
667 tap16_to_cpu(q, vnet_hdr.csum_start) +
668 tap16_to_cpu(q, vnet_hdr.csum_offset) + 2 >
669 tap16_to_cpu(q, vnet_hdr.hdr_len))
670 vnet_hdr.hdr_len = cpu_to_tap16(q,
671 tap16_to_cpu(q, vnet_hdr.csum_start) +
672 tap16_to_cpu(q, vnet_hdr.csum_offset) + 2);
673 err = -EINVAL;
674 if (tap16_to_cpu(q, vnet_hdr.hdr_len) > len)
675 goto err;
676 }
677
678 err = -EINVAL;
679 if (unlikely(len < ETH_HLEN))
680 goto err;
681
682 if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) {
683 struct iov_iter i;
684
685 copylen = vnet_hdr.hdr_len ?
686 tap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN;
687 if (copylen > good_linear)
688 copylen = good_linear;
689 else if (copylen < ETH_HLEN)
690 copylen = ETH_HLEN;
691 linear = copylen;
692 i = *from;
693 iov_iter_advance(&i, copylen);
694 if (iov_iter_npages(&i, INT_MAX) <= MAX_SKB_FRAGS)
695 zerocopy = true;
696 }
697
698 if (!zerocopy) {
699 copylen = len;
700 linear = tap16_to_cpu(q, vnet_hdr.hdr_len);
701 if (linear > good_linear)
702 linear = good_linear;
703 else if (linear < ETH_HLEN)
704 linear = ETH_HLEN;
705 }
706
707 skb = tap_alloc_skb(&q->sk, TAP_RESERVE, copylen,
708 linear, noblock, &err);
709 if (!skb)
710 goto err;
711
712 if (zerocopy)
713 err = zerocopy_sg_from_iter(skb, from);
714 else
715 err = skb_copy_datagram_from_iter(skb, 0, from, len);
716
717 if (err) {
718 drop_reason = SKB_DROP_REASON_SKB_UCOPY_FAULT;
719 goto err_kfree;
720 }
721
722 skb_set_network_header(skb, ETH_HLEN);
723 skb_reset_mac_header(skb);
724 skb->protocol = eth_hdr(skb)->h_proto;
725
726 rcu_read_lock();
727 tap = rcu_dereference(q->tap);
728 if (!tap) {
729 kfree_skb(skb);
730 rcu_read_unlock();
731 return total_len;
732 }
733 skb->dev = tap->dev;
734
735 if (vnet_hdr_len) {
736 err = virtio_net_hdr_to_skb(skb, &vnet_hdr,
737 tap_is_little_endian(q));
738 if (err) {
739 rcu_read_unlock();
740 drop_reason = SKB_DROP_REASON_DEV_HDR;
741 goto err_kfree;
742 }
743 }
744
745 skb_probe_transport_header(skb);
746
747 /* Move network header to the right position for VLAN tagged packets */
748 if (eth_type_vlan(skb->protocol) &&
749 vlan_get_protocol_and_depth(skb, skb->protocol, &depth) != 0)
750 skb_set_network_header(skb, depth);
751
752 /* copy skb_ubuf_info for callback when skb has no error */
753 if (zerocopy) {
754 skb_zcopy_init(skb, msg_control);
755 } else if (msg_control) {
756 struct ubuf_info *uarg = msg_control;
757 uarg->ops->complete(NULL, uarg, false);
758 }
759
760 dev_queue_xmit(skb);
761 rcu_read_unlock();
762 return total_len;
763
764 err_kfree:
765 kfree_skb_reason(skb, drop_reason);
766
767 err:
768 rcu_read_lock();
769 tap = rcu_dereference(q->tap);
770 if (tap && tap->count_tx_dropped)
771 tap->count_tx_dropped(tap);
772 rcu_read_unlock();
773
774 return err;
775 }
776
tap_write_iter(struct kiocb * iocb,struct iov_iter * from)777 static ssize_t tap_write_iter(struct kiocb *iocb, struct iov_iter *from)
778 {
779 struct file *file = iocb->ki_filp;
780 struct tap_queue *q = file->private_data;
781 int noblock = 0;
782
783 if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
784 noblock = 1;
785
786 return tap_get_user(q, NULL, from, noblock);
787 }
788
789 /* Put packet to the user space buffer */
tap_put_user(struct tap_queue * q,const struct sk_buff * skb,struct iov_iter * iter)790 static ssize_t tap_put_user(struct tap_queue *q,
791 const struct sk_buff *skb,
792 struct iov_iter *iter)
793 {
794 int ret;
795 int vnet_hdr_len = 0;
796 int vlan_offset = 0;
797 int total;
798
799 if (q->flags & IFF_VNET_HDR) {
800 int vlan_hlen = skb_vlan_tag_present(skb) ? VLAN_HLEN : 0;
801 struct virtio_net_hdr vnet_hdr;
802
803 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
804 if (iov_iter_count(iter) < vnet_hdr_len)
805 return -EINVAL;
806
807 if (virtio_net_hdr_from_skb(skb, &vnet_hdr,
808 tap_is_little_endian(q), true,
809 vlan_hlen))
810 BUG();
811
812 if (copy_to_iter(&vnet_hdr, sizeof(vnet_hdr), iter) !=
813 sizeof(vnet_hdr))
814 return -EFAULT;
815
816 iov_iter_advance(iter, vnet_hdr_len - sizeof(vnet_hdr));
817 }
818 total = vnet_hdr_len;
819 total += skb->len;
820
821 if (skb_vlan_tag_present(skb)) {
822 struct {
823 __be16 h_vlan_proto;
824 __be16 h_vlan_TCI;
825 } veth;
826 veth.h_vlan_proto = skb->vlan_proto;
827 veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
828
829 vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
830 total += VLAN_HLEN;
831
832 ret = skb_copy_datagram_iter(skb, 0, iter, vlan_offset);
833 if (ret || !iov_iter_count(iter))
834 goto done;
835
836 ret = copy_to_iter(&veth, sizeof(veth), iter);
837 if (ret != sizeof(veth) || !iov_iter_count(iter))
838 goto done;
839 }
840
841 ret = skb_copy_datagram_iter(skb, vlan_offset, iter,
842 skb->len - vlan_offset);
843
844 done:
845 return ret ? ret : total;
846 }
847
tap_do_read(struct tap_queue * q,struct iov_iter * to,int noblock,struct sk_buff * skb)848 static ssize_t tap_do_read(struct tap_queue *q,
849 struct iov_iter *to,
850 int noblock, struct sk_buff *skb)
851 {
852 DEFINE_WAIT(wait);
853 ssize_t ret = 0;
854
855 if (!iov_iter_count(to)) {
856 kfree_skb(skb);
857 return 0;
858 }
859
860 if (skb)
861 goto put;
862
863 while (1) {
864 if (!noblock)
865 prepare_to_wait(sk_sleep(&q->sk), &wait,
866 TASK_INTERRUPTIBLE);
867
868 /* Read frames from the queue */
869 skb = ptr_ring_consume(&q->ring);
870 if (skb)
871 break;
872 if (noblock) {
873 ret = -EAGAIN;
874 break;
875 }
876 if (signal_pending(current)) {
877 ret = -ERESTARTSYS;
878 break;
879 }
880 /* Nothing to read, let's sleep */
881 schedule();
882 }
883 if (!noblock)
884 finish_wait(sk_sleep(&q->sk), &wait);
885
886 put:
887 if (skb) {
888 ret = tap_put_user(q, skb, to);
889 if (unlikely(ret < 0))
890 kfree_skb(skb);
891 else
892 consume_skb(skb);
893 }
894 return ret;
895 }
896
tap_read_iter(struct kiocb * iocb,struct iov_iter * to)897 static ssize_t tap_read_iter(struct kiocb *iocb, struct iov_iter *to)
898 {
899 struct file *file = iocb->ki_filp;
900 struct tap_queue *q = file->private_data;
901 ssize_t len = iov_iter_count(to), ret;
902 int noblock = 0;
903
904 if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
905 noblock = 1;
906
907 ret = tap_do_read(q, to, noblock, NULL);
908 ret = min_t(ssize_t, ret, len);
909 if (ret > 0)
910 iocb->ki_pos = ret;
911 return ret;
912 }
913
tap_get_tap_dev(struct tap_queue * q)914 static struct tap_dev *tap_get_tap_dev(struct tap_queue *q)
915 {
916 struct tap_dev *tap;
917
918 ASSERT_RTNL();
919 tap = rtnl_dereference(q->tap);
920 if (tap)
921 dev_hold(tap->dev);
922
923 return tap;
924 }
925
tap_put_tap_dev(struct tap_dev * tap)926 static void tap_put_tap_dev(struct tap_dev *tap)
927 {
928 dev_put(tap->dev);
929 }
930
tap_ioctl_set_queue(struct file * file,unsigned int flags)931 static int tap_ioctl_set_queue(struct file *file, unsigned int flags)
932 {
933 struct tap_queue *q = file->private_data;
934 struct tap_dev *tap;
935 int ret;
936
937 tap = tap_get_tap_dev(q);
938 if (!tap)
939 return -EINVAL;
940
941 if (flags & IFF_ATTACH_QUEUE)
942 ret = tap_enable_queue(tap, file, q);
943 else if (flags & IFF_DETACH_QUEUE)
944 ret = tap_disable_queue(q);
945 else
946 ret = -EINVAL;
947
948 tap_put_tap_dev(tap);
949 return ret;
950 }
951
set_offload(struct tap_queue * q,unsigned long arg)952 static int set_offload(struct tap_queue *q, unsigned long arg)
953 {
954 struct tap_dev *tap;
955 netdev_features_t features;
956 netdev_features_t feature_mask = 0;
957
958 tap = rtnl_dereference(q->tap);
959 if (!tap)
960 return -ENOLINK;
961
962 features = tap->dev->features;
963
964 if (arg & TUN_F_CSUM) {
965 feature_mask = NETIF_F_HW_CSUM;
966
967 if (arg & (TUN_F_TSO4 | TUN_F_TSO6)) {
968 if (arg & TUN_F_TSO_ECN)
969 feature_mask |= NETIF_F_TSO_ECN;
970 if (arg & TUN_F_TSO4)
971 feature_mask |= NETIF_F_TSO;
972 if (arg & TUN_F_TSO6)
973 feature_mask |= NETIF_F_TSO6;
974 }
975
976 /* TODO: for now USO4 and USO6 should work simultaneously */
977 if ((arg & (TUN_F_USO4 | TUN_F_USO6)) == (TUN_F_USO4 | TUN_F_USO6))
978 features |= NETIF_F_GSO_UDP_L4;
979 }
980
981 /* tun/tap driver inverts the usage for TSO offloads, where
982 * setting the TSO bit means that the userspace wants to
983 * accept TSO frames and turning it off means that user space
984 * does not support TSO.
985 * For tap, we have to invert it to mean the same thing.
986 * When user space turns off TSO, we turn off GSO/LRO so that
987 * user-space will not receive TSO frames.
988 */
989 if (feature_mask & (NETIF_F_TSO | NETIF_F_TSO6) ||
990 (feature_mask & (TUN_F_USO4 | TUN_F_USO6)) == (TUN_F_USO4 | TUN_F_USO6))
991 features |= RX_OFFLOADS;
992 else
993 features &= ~RX_OFFLOADS;
994
995 /* tap_features are the same as features on tun/tap and
996 * reflect user expectations.
997 */
998 tap->tap_features = feature_mask;
999 if (tap->update_features)
1000 tap->update_features(tap, features);
1001
1002 return 0;
1003 }
1004
1005 /*
1006 * provide compatibility with generic tun/tap interface
1007 */
tap_ioctl(struct file * file,unsigned int cmd,unsigned long arg)1008 static long tap_ioctl(struct file *file, unsigned int cmd,
1009 unsigned long arg)
1010 {
1011 struct tap_queue *q = file->private_data;
1012 struct tap_dev *tap;
1013 void __user *argp = (void __user *)arg;
1014 struct ifreq __user *ifr = argp;
1015 unsigned int __user *up = argp;
1016 unsigned short u;
1017 int __user *sp = argp;
1018 struct sockaddr sa;
1019 int s;
1020 int ret;
1021
1022 switch (cmd) {
1023 case TUNSETIFF:
1024 /* ignore the name, just look at flags */
1025 if (get_user(u, &ifr->ifr_flags))
1026 return -EFAULT;
1027
1028 ret = 0;
1029 if ((u & ~TAP_IFFEATURES) != (IFF_NO_PI | IFF_TAP))
1030 ret = -EINVAL;
1031 else
1032 q->flags = (q->flags & ~TAP_IFFEATURES) | u;
1033
1034 return ret;
1035
1036 case TUNGETIFF:
1037 rtnl_lock();
1038 tap = tap_get_tap_dev(q);
1039 if (!tap) {
1040 rtnl_unlock();
1041 return -ENOLINK;
1042 }
1043
1044 ret = 0;
1045 u = q->flags;
1046 if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) ||
1047 put_user(u, &ifr->ifr_flags))
1048 ret = -EFAULT;
1049 tap_put_tap_dev(tap);
1050 rtnl_unlock();
1051 return ret;
1052
1053 case TUNSETQUEUE:
1054 if (get_user(u, &ifr->ifr_flags))
1055 return -EFAULT;
1056 rtnl_lock();
1057 ret = tap_ioctl_set_queue(file, u);
1058 rtnl_unlock();
1059 return ret;
1060
1061 case TUNGETFEATURES:
1062 if (put_user(IFF_TAP | IFF_NO_PI | TAP_IFFEATURES, up))
1063 return -EFAULT;
1064 return 0;
1065
1066 case TUNSETSNDBUF:
1067 if (get_user(s, sp))
1068 return -EFAULT;
1069 if (s <= 0)
1070 return -EINVAL;
1071
1072 q->sk.sk_sndbuf = s;
1073 return 0;
1074
1075 case TUNGETVNETHDRSZ:
1076 s = q->vnet_hdr_sz;
1077 if (put_user(s, sp))
1078 return -EFAULT;
1079 return 0;
1080
1081 case TUNSETVNETHDRSZ:
1082 if (get_user(s, sp))
1083 return -EFAULT;
1084 if (s < (int)sizeof(struct virtio_net_hdr))
1085 return -EINVAL;
1086
1087 q->vnet_hdr_sz = s;
1088 return 0;
1089
1090 case TUNGETVNETLE:
1091 s = !!(q->flags & TAP_VNET_LE);
1092 if (put_user(s, sp))
1093 return -EFAULT;
1094 return 0;
1095
1096 case TUNSETVNETLE:
1097 if (get_user(s, sp))
1098 return -EFAULT;
1099 if (s)
1100 q->flags |= TAP_VNET_LE;
1101 else
1102 q->flags &= ~TAP_VNET_LE;
1103 return 0;
1104
1105 case TUNGETVNETBE:
1106 return tap_get_vnet_be(q, sp);
1107
1108 case TUNSETVNETBE:
1109 return tap_set_vnet_be(q, sp);
1110
1111 case TUNSETOFFLOAD:
1112 /* let the user check for future flags */
1113 if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
1114 TUN_F_TSO_ECN | TUN_F_UFO |
1115 TUN_F_USO4 | TUN_F_USO6))
1116 return -EINVAL;
1117
1118 rtnl_lock();
1119 ret = set_offload(q, arg);
1120 rtnl_unlock();
1121 return ret;
1122
1123 case SIOCGIFHWADDR:
1124 rtnl_lock();
1125 tap = tap_get_tap_dev(q);
1126 if (!tap) {
1127 rtnl_unlock();
1128 return -ENOLINK;
1129 }
1130 ret = 0;
1131 dev_get_mac_address(&sa, dev_net(tap->dev), tap->dev->name);
1132 if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) ||
1133 copy_to_user(&ifr->ifr_hwaddr, &sa, sizeof(sa)))
1134 ret = -EFAULT;
1135 tap_put_tap_dev(tap);
1136 rtnl_unlock();
1137 return ret;
1138
1139 case SIOCSIFHWADDR:
1140 if (copy_from_user(&sa, &ifr->ifr_hwaddr, sizeof(sa)))
1141 return -EFAULT;
1142 rtnl_lock();
1143 tap = tap_get_tap_dev(q);
1144 if (!tap) {
1145 rtnl_unlock();
1146 return -ENOLINK;
1147 }
1148 ret = dev_set_mac_address_user(tap->dev, &sa, NULL);
1149 tap_put_tap_dev(tap);
1150 rtnl_unlock();
1151 return ret;
1152
1153 default:
1154 return -EINVAL;
1155 }
1156 }
1157
1158 static const struct file_operations tap_fops = {
1159 .owner = THIS_MODULE,
1160 .open = tap_open,
1161 .release = tap_release,
1162 .read_iter = tap_read_iter,
1163 .write_iter = tap_write_iter,
1164 .poll = tap_poll,
1165 .unlocked_ioctl = tap_ioctl,
1166 .compat_ioctl = compat_ptr_ioctl,
1167 };
1168
tap_get_user_xdp(struct tap_queue * q,struct xdp_buff * xdp)1169 static int tap_get_user_xdp(struct tap_queue *q, struct xdp_buff *xdp)
1170 {
1171 struct tun_xdp_hdr *hdr = xdp->data_hard_start;
1172 struct virtio_net_hdr *gso = &hdr->gso;
1173 int buflen = hdr->buflen;
1174 int vnet_hdr_len = 0;
1175 struct tap_dev *tap;
1176 struct sk_buff *skb;
1177 int err, depth;
1178
1179 if (unlikely(xdp->data_end - xdp->data < ETH_HLEN)) {
1180 err = -EINVAL;
1181 goto err;
1182 }
1183
1184 if (q->flags & IFF_VNET_HDR)
1185 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
1186
1187 skb = build_skb(xdp->data_hard_start, buflen);
1188 if (!skb) {
1189 err = -ENOMEM;
1190 goto err;
1191 }
1192
1193 skb_reserve(skb, xdp->data - xdp->data_hard_start);
1194 skb_put(skb, xdp->data_end - xdp->data);
1195
1196 skb_set_network_header(skb, ETH_HLEN);
1197 skb_reset_mac_header(skb);
1198 skb->protocol = eth_hdr(skb)->h_proto;
1199
1200 if (vnet_hdr_len) {
1201 err = virtio_net_hdr_to_skb(skb, gso, tap_is_little_endian(q));
1202 if (err)
1203 goto err_kfree;
1204 }
1205
1206 /* Move network header to the right position for VLAN tagged packets */
1207 if (eth_type_vlan(skb->protocol) &&
1208 vlan_get_protocol_and_depth(skb, skb->protocol, &depth) != 0)
1209 skb_set_network_header(skb, depth);
1210
1211 rcu_read_lock();
1212 tap = rcu_dereference(q->tap);
1213 if (tap) {
1214 skb->dev = tap->dev;
1215 skb_probe_transport_header(skb);
1216 dev_queue_xmit(skb);
1217 } else {
1218 kfree_skb(skb);
1219 }
1220 rcu_read_unlock();
1221
1222 return 0;
1223
1224 err_kfree:
1225 kfree_skb(skb);
1226 err:
1227 rcu_read_lock();
1228 tap = rcu_dereference(q->tap);
1229 if (tap && tap->count_tx_dropped)
1230 tap->count_tx_dropped(tap);
1231 rcu_read_unlock();
1232 return err;
1233 }
1234
tap_sendmsg(struct socket * sock,struct msghdr * m,size_t total_len)1235 static int tap_sendmsg(struct socket *sock, struct msghdr *m,
1236 size_t total_len)
1237 {
1238 struct tap_queue *q = container_of(sock, struct tap_queue, sock);
1239 struct tun_msg_ctl *ctl = m->msg_control;
1240 struct xdp_buff *xdp;
1241 int i;
1242
1243 if (m->msg_controllen == sizeof(struct tun_msg_ctl) &&
1244 ctl && ctl->type == TUN_MSG_PTR) {
1245 for (i = 0; i < ctl->num; i++) {
1246 xdp = &((struct xdp_buff *)ctl->ptr)[i];
1247 tap_get_user_xdp(q, xdp);
1248 }
1249 return 0;
1250 }
1251
1252 return tap_get_user(q, ctl ? ctl->ptr : NULL, &m->msg_iter,
1253 m->msg_flags & MSG_DONTWAIT);
1254 }
1255
tap_recvmsg(struct socket * sock,struct msghdr * m,size_t total_len,int flags)1256 static int tap_recvmsg(struct socket *sock, struct msghdr *m,
1257 size_t total_len, int flags)
1258 {
1259 struct tap_queue *q = container_of(sock, struct tap_queue, sock);
1260 struct sk_buff *skb = m->msg_control;
1261 int ret;
1262 if (flags & ~(MSG_DONTWAIT|MSG_TRUNC)) {
1263 kfree_skb(skb);
1264 return -EINVAL;
1265 }
1266 ret = tap_do_read(q, &m->msg_iter, flags & MSG_DONTWAIT, skb);
1267 if (ret > total_len) {
1268 m->msg_flags |= MSG_TRUNC;
1269 ret = flags & MSG_TRUNC ? ret : total_len;
1270 }
1271 return ret;
1272 }
1273
tap_peek_len(struct socket * sock)1274 static int tap_peek_len(struct socket *sock)
1275 {
1276 struct tap_queue *q = container_of(sock, struct tap_queue,
1277 sock);
1278 return PTR_RING_PEEK_CALL(&q->ring, __skb_array_len_with_tag);
1279 }
1280
1281 /* Ops structure to mimic raw sockets with tun */
1282 static const struct proto_ops tap_socket_ops = {
1283 .sendmsg = tap_sendmsg,
1284 .recvmsg = tap_recvmsg,
1285 .peek_len = tap_peek_len,
1286 };
1287
1288 /* Get an underlying socket object from tun file. Returns error unless file is
1289 * attached to a device. The returned object works like a packet socket, it
1290 * can be used for sock_sendmsg/sock_recvmsg. The caller is responsible for
1291 * holding a reference to the file for as long as the socket is in use. */
tap_get_socket(struct file * file)1292 struct socket *tap_get_socket(struct file *file)
1293 {
1294 struct tap_queue *q;
1295 if (file->f_op != &tap_fops)
1296 return ERR_PTR(-EINVAL);
1297 q = file->private_data;
1298 if (!q)
1299 return ERR_PTR(-EBADFD);
1300 return &q->sock;
1301 }
1302 EXPORT_SYMBOL_GPL(tap_get_socket);
1303
tap_get_ptr_ring(struct file * file)1304 struct ptr_ring *tap_get_ptr_ring(struct file *file)
1305 {
1306 struct tap_queue *q;
1307
1308 if (file->f_op != &tap_fops)
1309 return ERR_PTR(-EINVAL);
1310 q = file->private_data;
1311 if (!q)
1312 return ERR_PTR(-EBADFD);
1313 return &q->ring;
1314 }
1315 EXPORT_SYMBOL_GPL(tap_get_ptr_ring);
1316
tap_queue_resize(struct tap_dev * tap)1317 int tap_queue_resize(struct tap_dev *tap)
1318 {
1319 struct net_device *dev = tap->dev;
1320 struct tap_queue *q;
1321 struct ptr_ring **rings;
1322 int n = tap->numqueues;
1323 int ret, i = 0;
1324
1325 rings = kmalloc_array(n, sizeof(*rings), GFP_KERNEL);
1326 if (!rings)
1327 return -ENOMEM;
1328
1329 list_for_each_entry(q, &tap->queue_list, next)
1330 rings[i++] = &q->ring;
1331
1332 ret = ptr_ring_resize_multiple(rings, n,
1333 dev->tx_queue_len, GFP_KERNEL,
1334 __skb_array_destroy_skb);
1335
1336 kfree(rings);
1337 return ret;
1338 }
1339 EXPORT_SYMBOL_GPL(tap_queue_resize);
1340
tap_list_add(dev_t major,const char * device_name)1341 static int tap_list_add(dev_t major, const char *device_name)
1342 {
1343 struct major_info *tap_major;
1344
1345 tap_major = kzalloc(sizeof(*tap_major), GFP_ATOMIC);
1346 if (!tap_major)
1347 return -ENOMEM;
1348
1349 tap_major->major = MAJOR(major);
1350
1351 idr_init(&tap_major->minor_idr);
1352 spin_lock_init(&tap_major->minor_lock);
1353
1354 tap_major->device_name = device_name;
1355
1356 list_add_tail_rcu(&tap_major->next, &major_list);
1357 return 0;
1358 }
1359
tap_create_cdev(struct cdev * tap_cdev,dev_t * tap_major,const char * device_name,struct module * module)1360 int tap_create_cdev(struct cdev *tap_cdev, dev_t *tap_major,
1361 const char *device_name, struct module *module)
1362 {
1363 int err;
1364
1365 err = alloc_chrdev_region(tap_major, 0, TAP_NUM_DEVS, device_name);
1366 if (err)
1367 goto out1;
1368
1369 cdev_init(tap_cdev, &tap_fops);
1370 tap_cdev->owner = module;
1371 err = cdev_add(tap_cdev, *tap_major, TAP_NUM_DEVS);
1372 if (err)
1373 goto out2;
1374
1375 err = tap_list_add(*tap_major, device_name);
1376 if (err)
1377 goto out3;
1378
1379 return 0;
1380
1381 out3:
1382 cdev_del(tap_cdev);
1383 out2:
1384 unregister_chrdev_region(*tap_major, TAP_NUM_DEVS);
1385 out1:
1386 return err;
1387 }
1388 EXPORT_SYMBOL_GPL(tap_create_cdev);
1389
tap_destroy_cdev(dev_t major,struct cdev * tap_cdev)1390 void tap_destroy_cdev(dev_t major, struct cdev *tap_cdev)
1391 {
1392 struct major_info *tap_major, *tmp;
1393
1394 cdev_del(tap_cdev);
1395 unregister_chrdev_region(major, TAP_NUM_DEVS);
1396 list_for_each_entry_safe(tap_major, tmp, &major_list, next) {
1397 if (tap_major->major == MAJOR(major)) {
1398 idr_destroy(&tap_major->minor_idr);
1399 list_del_rcu(&tap_major->next);
1400 kfree_rcu(tap_major, rcu);
1401 }
1402 }
1403 }
1404 EXPORT_SYMBOL_GPL(tap_destroy_cdev);
1405
1406 MODULE_DESCRIPTION("Common library for drivers implementing the TAP interface");
1407 MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>");
1408 MODULE_AUTHOR("Sainath Grandhi <sainath.grandhi@intel.com>");
1409 MODULE_LICENSE("GPL");
1410