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