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Merge tag 'for-linus-20190706' of git://git.kernel.dk/linux-block
[linux/fpc-iii.git] / drivers / net / tap.c
blob8e01390c738e8ce0a01c16a6cca2865df02d6c04
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/net_namespace.h>
22 #include <net/rtnetlink.h>
23 #include <net/sock.h>
24 #include <linux/virtio_net.h>
25 #include <linux/skb_array.h>
26
27 #define TAP_IFFEATURES (IFF_VNET_HDR | IFF_MULTI_QUEUE)
28
29 #define TAP_VNET_LE 0x80000000
30 #define TAP_VNET_BE 0x40000000
31
32 #ifdef CONFIG_TUN_VNET_CROSS_LE
33 static inline bool tap_legacy_is_little_endian(struct tap_queue *q)
34 {
35 return q->flags & TAP_VNET_BE ? false :
36 virtio_legacy_is_little_endian();
37 }
38
39 static long tap_get_vnet_be(struct tap_queue *q, int __user *sp)
40 {
41 int s = !!(q->flags & TAP_VNET_BE);
42
43 if (put_user(s, sp))
44 return -EFAULT;
45
46 return 0;
47 }
48
49 static long tap_set_vnet_be(struct tap_queue *q, int __user *sp)
50 {
51 int s;
52
53 if (get_user(s, sp))
54 return -EFAULT;
55
56 if (s)
57 q->flags |= TAP_VNET_BE;
58 else
59 q->flags &= ~TAP_VNET_BE;
60
61 return 0;
62 }
63 #else
64 static inline bool tap_legacy_is_little_endian(struct tap_queue *q)
65 {
66 return virtio_legacy_is_little_endian();
67 }
68
69 static long tap_get_vnet_be(struct tap_queue *q, int __user *argp)
70 {
71 return -EINVAL;
72 }
73
74 static long tap_set_vnet_be(struct tap_queue *q, int __user *argp)
75 {
76 return -EINVAL;
77 }
78 #endif /* CONFIG_TUN_VNET_CROSS_LE */
79
80 static inline bool tap_is_little_endian(struct tap_queue *q)
81 {
82 return q->flags & TAP_VNET_LE ||
83 tap_legacy_is_little_endian(q);
84 }
85
86 static inline u16 tap16_to_cpu(struct tap_queue *q, __virtio16 val)
87 {
88 return __virtio16_to_cpu(tap_is_little_endian(q), val);
89 }
90
91 static inline __virtio16 cpu_to_tap16(struct tap_queue *q, u16 val)
92 {
93 return __cpu_to_virtio16(tap_is_little_endian(q), val);
94 }
95
96 static struct proto tap_proto = {
97 .name = "tap",
98 .owner = THIS_MODULE,
99 .obj_size = sizeof(struct tap_queue),
100 };
101
102 #define TAP_NUM_DEVS (1U << MINORBITS)
103
104 static LIST_HEAD(major_list);
105
106 struct major_info {
107 struct rcu_head rcu;
108 dev_t major;
109 struct idr minor_idr;
110 spinlock_t minor_lock;
111 const char *device_name;
112 struct list_head next;
113 };
114
115 #define GOODCOPY_LEN 128
116
117 static const struct proto_ops tap_socket_ops;
118
119 #define RX_OFFLOADS (NETIF_F_GRO | NETIF_F_LRO)
120 #define TAP_FEATURES (NETIF_F_GSO | NETIF_F_SG | NETIF_F_FRAGLIST)
121
122 static struct tap_dev *tap_dev_get_rcu(const struct net_device *dev)
123 {
124 return rcu_dereference(dev->rx_handler_data);
125 }
126
127 /*
128 * RCU usage:
129 * The tap_queue and the macvlan_dev are loosely coupled, the
130 * pointers from one to the other can only be read while rcu_read_lock
131 * or rtnl is held.
132 *
133 * Both the file and the macvlan_dev hold a reference on the tap_queue
134 * through sock_hold(&q->sk). When the macvlan_dev goes away first,
135 * q->vlan becomes inaccessible. When the files gets closed,
136 * tap_get_queue() fails.
137 *
138 * There may still be references to the struct sock inside of the
139 * queue from outbound SKBs, but these never reference back to the
140 * file or the dev. The data structure is freed through __sk_free
141 * when both our references and any pending SKBs are gone.
142 */
143
144 static int tap_enable_queue(struct tap_dev *tap, struct file *file,
145 struct tap_queue *q)
146 {
147 int err = -EINVAL;
148
149 ASSERT_RTNL();
150
151 if (q->enabled)
152 goto out;
153
154 err = 0;
155 rcu_assign_pointer(tap->taps[tap->numvtaps], q);
156 q->queue_index = tap->numvtaps;
157 q->enabled = true;
158
159 tap->numvtaps++;
160 out:
161 return err;
162 }
163
164 /* Requires RTNL */
165 static int tap_set_queue(struct tap_dev *tap, struct file *file,
166 struct tap_queue *q)
167 {
168 if (tap->numqueues == MAX_TAP_QUEUES)
169 return -EBUSY;
170
171 rcu_assign_pointer(q->tap, tap);
172 rcu_assign_pointer(tap->taps[tap->numvtaps], q);
173 sock_hold(&q->sk);
174
175 q->file = file;
176 q->queue_index = tap->numvtaps;
177 q->enabled = true;
178 file->private_data = q;
179 list_add_tail(&q->next, &tap->queue_list);
180
181 tap->numvtaps++;
182 tap->numqueues++;
183
184 return 0;
185 }
186
187 static int tap_disable_queue(struct tap_queue *q)
188 {
189 struct tap_dev *tap;
190 struct tap_queue *nq;
191
192 ASSERT_RTNL();
193 if (!q->enabled)
194 return -EINVAL;
195
196 tap = rtnl_dereference(q->tap);
197
198 if (tap) {
199 int index = q->queue_index;
200 BUG_ON(index >= tap->numvtaps);
201 nq = rtnl_dereference(tap->taps[tap->numvtaps - 1]);
202 nq->queue_index = index;
203
204 rcu_assign_pointer(tap->taps[index], nq);
205 RCU_INIT_POINTER(tap->taps[tap->numvtaps - 1], NULL);
206 q->enabled = false;
207
208 tap->numvtaps--;
209 }
210
211 return 0;
212 }
213
214 /*
215 * The file owning the queue got closed, give up both
216 * the reference that the files holds as well as the
217 * one from the macvlan_dev if that still exists.
218 *
219 * Using the spinlock makes sure that we don't get
220 * to the queue again after destroying it.
221 */
222 static void tap_put_queue(struct tap_queue *q)
223 {
224 struct tap_dev *tap;
225
226 rtnl_lock();
227 tap = rtnl_dereference(q->tap);
228
229 if (tap) {
230 if (q->enabled)
231 BUG_ON(tap_disable_queue(q));
232
233 tap->numqueues--;
234 RCU_INIT_POINTER(q->tap, NULL);
235 sock_put(&q->sk);
236 list_del_init(&q->next);
237 }
238
239 rtnl_unlock();
240
241 synchronize_rcu();
242 sock_put(&q->sk);
243 }
244
245 /*
246 * Select a queue based on the rxq of the device on which this packet
247 * arrived. If the incoming device is not mq, calculate a flow hash
248 * to select a queue. If all fails, find the first available queue.
249 * Cache vlan->numvtaps since it can become zero during the execution
250 * of this function.
251 */
252 static struct tap_queue *tap_get_queue(struct tap_dev *tap,
253 struct sk_buff *skb)
254 {
255 struct tap_queue *queue = NULL;
256 /* Access to taps array is protected by rcu, but access to numvtaps
257 * isn't. Below we use it to lookup a queue, but treat it as a hint
258 * and validate that the result isn't NULL - in case we are
259 * racing against queue removal.
260 */
261 int numvtaps = READ_ONCE(tap->numvtaps);
262 __u32 rxq;
263
264 if (!numvtaps)
265 goto out;
266
267 if (numvtaps == 1)
268 goto single;
269
270 /* Check if we can use flow to select a queue */
271 rxq = skb_get_hash(skb);
272 if (rxq) {
273 queue = rcu_dereference(tap->taps[rxq % numvtaps]);
274 goto out;
275 }
276
277 if (likely(skb_rx_queue_recorded(skb))) {
278 rxq = skb_get_rx_queue(skb);
279
280 while (unlikely(rxq >= numvtaps))
281 rxq -= numvtaps;
282
283 queue = rcu_dereference(tap->taps[rxq]);
284 goto out;
285 }
286
287 single:
288 queue = rcu_dereference(tap->taps[0]);
289 out:
290 return queue;
291 }
292
293 /*
294 * The net_device is going away, give up the reference
295 * that it holds on all queues and safely set the pointer
296 * from the queues to NULL.
297 */
298 void tap_del_queues(struct tap_dev *tap)
299 {
300 struct tap_queue *q, *tmp;
301
302 ASSERT_RTNL();
303 list_for_each_entry_safe(q, tmp, &tap->queue_list, next) {
304 list_del_init(&q->next);
305 RCU_INIT_POINTER(q->tap, NULL);
306 if (q->enabled)
307 tap->numvtaps--;
308 tap->numqueues--;
309 sock_put(&q->sk);
310 }
311 BUG_ON(tap->numvtaps);
312 BUG_ON(tap->numqueues);
313 /* guarantee that any future tap_set_queue will fail */
314 tap->numvtaps = MAX_TAP_QUEUES;
315 }
316 EXPORT_SYMBOL_GPL(tap_del_queues);
317
318 rx_handler_result_t tap_handle_frame(struct sk_buff **pskb)
319 {
320 struct sk_buff *skb = *pskb;
321 struct net_device *dev = skb->dev;
322 struct tap_dev *tap;
323 struct tap_queue *q;
324 netdev_features_t features = TAP_FEATURES;
325
326 tap = tap_dev_get_rcu(dev);
327 if (!tap)
328 return RX_HANDLER_PASS;
329
330 q = tap_get_queue(tap, skb);
331 if (!q)
332 return RX_HANDLER_PASS;
333
334 skb_push(skb, ETH_HLEN);
335
336 /* Apply the forward feature mask so that we perform segmentation
337 * according to users wishes. This only works if VNET_HDR is
338 * enabled.
339 */
340 if (q->flags & IFF_VNET_HDR)
341 features |= tap->tap_features;
342 if (netif_needs_gso(skb, features)) {
343 struct sk_buff *segs = __skb_gso_segment(skb, features, false);
344
345 if (IS_ERR(segs))
346 goto drop;
347
348 if (!segs) {
349 if (ptr_ring_produce(&q->ring, skb))
350 goto drop;
351 goto wake_up;
352 }
353
354 consume_skb(skb);
355 while (segs) {
356 struct sk_buff *nskb = segs->next;
357
358 segs->next = NULL;
359 if (ptr_ring_produce(&q->ring, segs)) {
360 kfree_skb(segs);
361 kfree_skb_list(nskb);
362 break;
363 }
364 segs = nskb;
365 }
366 } else {
367 /* If we receive a partial checksum and the tap side
368 * doesn't support checksum offload, compute the checksum.
369 * Note: it doesn't matter which checksum feature to
370 * check, we either support them all or none.
371 */
372 if (skb->ip_summed == CHECKSUM_PARTIAL &&
373 !(features & NETIF_F_CSUM_MASK) &&
374 skb_checksum_help(skb))
375 goto drop;
376 if (ptr_ring_produce(&q->ring, skb))
377 goto drop;
378 }
379
380 wake_up:
381 wake_up_interruptible_poll(sk_sleep(&q->sk), EPOLLIN | EPOLLRDNORM | EPOLLRDBAND);
382 return RX_HANDLER_CONSUMED;
383
384 drop:
385 /* Count errors/drops only here, thus don't care about args. */
386 if (tap->count_rx_dropped)
387 tap->count_rx_dropped(tap);
388 kfree_skb(skb);
389 return RX_HANDLER_CONSUMED;
390 }
391 EXPORT_SYMBOL_GPL(tap_handle_frame);
392
393 static struct major_info *tap_get_major(int major)
394 {
395 struct major_info *tap_major;
396
397 list_for_each_entry_rcu(tap_major, &major_list, next) {
398 if (tap_major->major == major)
399 return tap_major;
400 }
401
402 return NULL;
403 }
404
405 int tap_get_minor(dev_t major, struct tap_dev *tap)
406 {
407 int retval = -ENOMEM;
408 struct major_info *tap_major;
409
410 rcu_read_lock();
411 tap_major = tap_get_major(MAJOR(major));
412 if (!tap_major) {
413 retval = -EINVAL;
414 goto unlock;
415 }
416
417 spin_lock(&tap_major->minor_lock);
418 retval = idr_alloc(&tap_major->minor_idr, tap, 1, TAP_NUM_DEVS, GFP_ATOMIC);
419 if (retval >= 0) {
420 tap->minor = retval;
421 } else if (retval == -ENOSPC) {
422 netdev_err(tap->dev, "Too many tap devices\n");
423 retval = -EINVAL;
424 }
425 spin_unlock(&tap_major->minor_lock);
426
427 unlock:
428 rcu_read_unlock();
429 return retval < 0 ? retval : 0;
430 }
431 EXPORT_SYMBOL_GPL(tap_get_minor);
432
433 void tap_free_minor(dev_t major, struct tap_dev *tap)
434 {
435 struct major_info *tap_major;
436
437 rcu_read_lock();
438 tap_major = tap_get_major(MAJOR(major));
439 if (!tap_major) {
440 goto unlock;
441 }
442
443 spin_lock(&tap_major->minor_lock);
444 if (tap->minor) {
445 idr_remove(&tap_major->minor_idr, tap->minor);
446 tap->minor = 0;
447 }
448 spin_unlock(&tap_major->minor_lock);
449
450 unlock:
451 rcu_read_unlock();
452 }
453 EXPORT_SYMBOL_GPL(tap_free_minor);
454
455 static struct tap_dev *dev_get_by_tap_file(int major, int minor)
456 {
457 struct net_device *dev = NULL;
458 struct tap_dev *tap;
459 struct major_info *tap_major;
460
461 rcu_read_lock();
462 tap_major = tap_get_major(major);
463 if (!tap_major) {
464 tap = NULL;
465 goto unlock;
466 }
467
468 spin_lock(&tap_major->minor_lock);
469 tap = idr_find(&tap_major->minor_idr, minor);
470 if (tap) {
471 dev = tap->dev;
472 dev_hold(dev);
473 }
474 spin_unlock(&tap_major->minor_lock);
475
476 unlock:
477 rcu_read_unlock();
478 return tap;
479 }
480
481 static void tap_sock_write_space(struct sock *sk)
482 {
483 wait_queue_head_t *wqueue;
484
485 if (!sock_writeable(sk) ||
486 !test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags))
487 return;
488
489 wqueue = sk_sleep(sk);
490 if (wqueue && waitqueue_active(wqueue))
491 wake_up_interruptible_poll(wqueue, EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND);
492 }
493
494 static void tap_sock_destruct(struct sock *sk)
495 {
496 struct tap_queue *q = container_of(sk, struct tap_queue, sk);
497
498 ptr_ring_cleanup(&q->ring, __skb_array_destroy_skb);
499 }
500
501 static int tap_open(struct inode *inode, struct file *file)
502 {
503 struct net *net = current->nsproxy->net_ns;
504 struct tap_dev *tap;
505 struct tap_queue *q;
506 int err = -ENODEV;
507
508 rtnl_lock();
509 tap = dev_get_by_tap_file(imajor(inode), iminor(inode));
510 if (!tap)
511 goto err;
512
513 err = -ENOMEM;
514 q = (struct tap_queue *)sk_alloc(net, AF_UNSPEC, GFP_KERNEL,
515 &tap_proto, 0);
516 if (!q)
517 goto err;
518 if (ptr_ring_init(&q->ring, tap->dev->tx_queue_len, GFP_KERNEL)) {
519 sk_free(&q->sk);
520 goto err;
521 }
522
523 RCU_INIT_POINTER(q->sock.wq, &q->wq);
524 init_waitqueue_head(&q->wq.wait);
525 q->sock.type = SOCK_RAW;
526 q->sock.state = SS_CONNECTED;
527 q->sock.file = file;
528 q->sock.ops = &tap_socket_ops;
529 sock_init_data(&q->sock, &q->sk);
530 q->sk.sk_write_space = tap_sock_write_space;
531 q->sk.sk_destruct = tap_sock_destruct;
532 q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP;
533 q->vnet_hdr_sz = sizeof(struct virtio_net_hdr);
534
535 /*
536 * so far only KVM virtio_net uses tap, enable zero copy between
537 * guest kernel and host kernel when lower device supports zerocopy
538 *
539 * The macvlan supports zerocopy iff the lower device supports zero
540 * copy so we don't have to look at the lower device directly.
541 */
542 if ((tap->dev->features & NETIF_F_HIGHDMA) && (tap->dev->features & NETIF_F_SG))
543 sock_set_flag(&q->sk, SOCK_ZEROCOPY);
544
545 err = tap_set_queue(tap, file, q);
546 if (err) {
547 /* tap_sock_destruct() will take care of freeing ptr_ring */
548 goto err_put;
549 }
550
551 dev_put(tap->dev);
552
553 rtnl_unlock();
554 return err;
555
556 err_put:
557 sock_put(&q->sk);
558 err:
559 if (tap)
560 dev_put(tap->dev);
561
562 rtnl_unlock();
563 return err;
564 }
565
566 static int tap_release(struct inode *inode, struct file *file)
567 {
568 struct tap_queue *q = file->private_data;
569 tap_put_queue(q);
570 return 0;
571 }
572
573 static __poll_t tap_poll(struct file *file, poll_table *wait)
574 {
575 struct tap_queue *q = file->private_data;
576 __poll_t mask = EPOLLERR;
577
578 if (!q)
579 goto out;
580
581 mask = 0;
582 poll_wait(file, &q->wq.wait, wait);
583
584 if (!ptr_ring_empty(&q->ring))
585 mask |= EPOLLIN | EPOLLRDNORM;
586
587 if (sock_writeable(&q->sk) ||
588 (!test_and_set_bit(SOCKWQ_ASYNC_NOSPACE, &q->sock.flags) &&
589 sock_writeable(&q->sk)))
590 mask |= EPOLLOUT | EPOLLWRNORM;
591
592 out:
593 return mask;
594 }
595
596 static inline struct sk_buff *tap_alloc_skb(struct sock *sk, size_t prepad,
597 size_t len, size_t linear,
598 int noblock, int *err)
599 {
600 struct sk_buff *skb;
601
602 /* Under a page? Don't bother with paged skb. */
603 if (prepad + len < PAGE_SIZE || !linear)
604 linear = len;
605
606 skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
607 err, 0);
608 if (!skb)
609 return NULL;
610
611 skb_reserve(skb, prepad);
612 skb_put(skb, linear);
613 skb->data_len = len - linear;
614 skb->len += len - linear;
615
616 return skb;
617 }
618
619 /* Neighbour code has some assumptions on HH_DATA_MOD alignment */
620 #define TAP_RESERVE HH_DATA_OFF(ETH_HLEN)
621
622 /* Get packet from user space buffer */
623 static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,
624 struct iov_iter *from, int noblock)
625 {
626 int good_linear = SKB_MAX_HEAD(TAP_RESERVE);
627 struct sk_buff *skb;
628 struct tap_dev *tap;
629 unsigned long total_len = iov_iter_count(from);
630 unsigned long len = total_len;
631 int err;
632 struct virtio_net_hdr vnet_hdr = { 0 };
633 int vnet_hdr_len = 0;
634 int copylen = 0;
635 int depth;
636 bool zerocopy = false;
637 size_t linear;
638
639 if (q->flags & IFF_VNET_HDR) {
640 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
641
642 err = -EINVAL;
643 if (len < vnet_hdr_len)
644 goto err;
645 len -= vnet_hdr_len;
646
647 err = -EFAULT;
648 if (!copy_from_iter_full(&vnet_hdr, sizeof(vnet_hdr), from))
649 goto err;
650 iov_iter_advance(from, vnet_hdr_len - sizeof(vnet_hdr));
651 if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
652 tap16_to_cpu(q, vnet_hdr.csum_start) +
653 tap16_to_cpu(q, vnet_hdr.csum_offset) + 2 >
654 tap16_to_cpu(q, vnet_hdr.hdr_len))
655 vnet_hdr.hdr_len = cpu_to_tap16(q,
656 tap16_to_cpu(q, vnet_hdr.csum_start) +
657 tap16_to_cpu(q, vnet_hdr.csum_offset) + 2);
658 err = -EINVAL;
659 if (tap16_to_cpu(q, vnet_hdr.hdr_len) > len)
660 goto err;
661 }
662
663 err = -EINVAL;
664 if (unlikely(len < ETH_HLEN))
665 goto err;
666
667 if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) {
668 struct iov_iter i;
669
670 copylen = vnet_hdr.hdr_len ?
671 tap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN;
672 if (copylen > good_linear)
673 copylen = good_linear;
674 else if (copylen < ETH_HLEN)
675 copylen = ETH_HLEN;
676 linear = copylen;
677 i = *from;
678 iov_iter_advance(&i, copylen);
679 if (iov_iter_npages(&i, INT_MAX) <= MAX_SKB_FRAGS)
680 zerocopy = true;
681 }
682
683 if (!zerocopy) {
684 copylen = len;
685 linear = tap16_to_cpu(q, vnet_hdr.hdr_len);
686 if (linear > good_linear)
687 linear = good_linear;
688 else if (linear < ETH_HLEN)
689 linear = ETH_HLEN;
690 }
691
692 skb = tap_alloc_skb(&q->sk, TAP_RESERVE, copylen,
693 linear, noblock, &err);
694 if (!skb)
695 goto err;
696
697 if (zerocopy)
698 err = zerocopy_sg_from_iter(skb, from);
699 else
700 err = skb_copy_datagram_from_iter(skb, 0, from, len);
701
702 if (err)
703 goto err_kfree;
704
705 skb_set_network_header(skb, ETH_HLEN);
706 skb_reset_mac_header(skb);
707 skb->protocol = eth_hdr(skb)->h_proto;
708
709 if (vnet_hdr_len) {
710 err = virtio_net_hdr_to_skb(skb, &vnet_hdr,
711 tap_is_little_endian(q));
712 if (err)
713 goto err_kfree;
714 }
715
716 skb_probe_transport_header(skb);
717
718 /* Move network header to the right position for VLAN tagged packets */
719 if ((skb->protocol == htons(ETH_P_8021Q) ||
720 skb->protocol == htons(ETH_P_8021AD)) &&
721 __vlan_get_protocol(skb, skb->protocol, &depth) != 0)
722 skb_set_network_header(skb, depth);
723
724 rcu_read_lock();
725 tap = rcu_dereference(q->tap);
726 /* copy skb_ubuf_info for callback when skb has no error */
727 if (zerocopy) {
728 skb_shinfo(skb)->destructor_arg = msg_control;
729 skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
730 skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
731 } else if (msg_control) {
732 struct ubuf_info *uarg = msg_control;
733 uarg->callback(uarg, false);
734 }
735
736 if (tap) {
737 skb->dev = tap->dev;
738 dev_queue_xmit(skb);
739 } else {
740 kfree_skb(skb);
741 }
742 rcu_read_unlock();
743
744 return total_len;
745
746 err_kfree:
747 kfree_skb(skb);
748
749 err:
750 rcu_read_lock();
751 tap = rcu_dereference(q->tap);
752 if (tap && tap->count_tx_dropped)
753 tap->count_tx_dropped(tap);
754 rcu_read_unlock();
755
756 return err;
757 }
758
759 static ssize_t tap_write_iter(struct kiocb *iocb, struct iov_iter *from)
760 {
761 struct file *file = iocb->ki_filp;
762 struct tap_queue *q = file->private_data;
763
764 return tap_get_user(q, NULL, from, file->f_flags & O_NONBLOCK);
765 }
766
767 /* Put packet to the user space buffer */
768 static ssize_t tap_put_user(struct tap_queue *q,
769 const struct sk_buff *skb,
770 struct iov_iter *iter)
771 {
772 int ret;
773 int vnet_hdr_len = 0;
774 int vlan_offset = 0;
775 int total;
776
777 if (q->flags & IFF_VNET_HDR) {
778 int vlan_hlen = skb_vlan_tag_present(skb) ? VLAN_HLEN : 0;
779 struct virtio_net_hdr vnet_hdr;
780
781 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
782 if (iov_iter_count(iter) < vnet_hdr_len)
783 return -EINVAL;
784
785 if (virtio_net_hdr_from_skb(skb, &vnet_hdr,
786 tap_is_little_endian(q), true,
787 vlan_hlen))
788 BUG();
789
790 if (copy_to_iter(&vnet_hdr, sizeof(vnet_hdr), iter) !=
791 sizeof(vnet_hdr))
792 return -EFAULT;
793
794 iov_iter_advance(iter, vnet_hdr_len - sizeof(vnet_hdr));
795 }
796 total = vnet_hdr_len;
797 total += skb->len;
798
799 if (skb_vlan_tag_present(skb)) {
800 struct {
801 __be16 h_vlan_proto;
802 __be16 h_vlan_TCI;
803 } veth;
804 veth.h_vlan_proto = skb->vlan_proto;
805 veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
806
807 vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
808 total += VLAN_HLEN;
809
810 ret = skb_copy_datagram_iter(skb, 0, iter, vlan_offset);
811 if (ret || !iov_iter_count(iter))
812 goto done;
813
814 ret = copy_to_iter(&veth, sizeof(veth), iter);
815 if (ret != sizeof(veth) || !iov_iter_count(iter))
816 goto done;
817 }
818
819 ret = skb_copy_datagram_iter(skb, vlan_offset, iter,
820 skb->len - vlan_offset);
821
822 done:
823 return ret ? ret : total;
824 }
825
826 static ssize_t tap_do_read(struct tap_queue *q,
827 struct iov_iter *to,
828 int noblock, struct sk_buff *skb)
829 {
830 DEFINE_WAIT(wait);
831 ssize_t ret = 0;
832
833 if (!iov_iter_count(to)) {
834 kfree_skb(skb);
835 return 0;
836 }
837
838 if (skb)
839 goto put;
840
841 while (1) {
842 if (!noblock)
843 prepare_to_wait(sk_sleep(&q->sk), &wait,
844 TASK_INTERRUPTIBLE);
845
846 /* Read frames from the queue */
847 skb = ptr_ring_consume(&q->ring);
848 if (skb)
849 break;
850 if (noblock) {
851 ret = -EAGAIN;
852 break;
853 }
854 if (signal_pending(current)) {
855 ret = -ERESTARTSYS;
856 break;
857 }
858 /* Nothing to read, let's sleep */
859 schedule();
860 }
861 if (!noblock)
862 finish_wait(sk_sleep(&q->sk), &wait);
863
864 put:
865 if (skb) {
866 ret = tap_put_user(q, skb, to);
867 if (unlikely(ret < 0))
868 kfree_skb(skb);
869 else
870 consume_skb(skb);
871 }
872 return ret;
873 }
874
875 static ssize_t tap_read_iter(struct kiocb *iocb, struct iov_iter *to)
876 {
877 struct file *file = iocb->ki_filp;
878 struct tap_queue *q = file->private_data;
879 ssize_t len = iov_iter_count(to), ret;
880
881 ret = tap_do_read(q, to, file->f_flags & O_NONBLOCK, NULL);
882 ret = min_t(ssize_t, ret, len);
883 if (ret > 0)
884 iocb->ki_pos = ret;
885 return ret;
886 }
887
888 static struct tap_dev *tap_get_tap_dev(struct tap_queue *q)
889 {
890 struct tap_dev *tap;
891
892 ASSERT_RTNL();
893 tap = rtnl_dereference(q->tap);
894 if (tap)
895 dev_hold(tap->dev);
896
897 return tap;
898 }
899
900 static void tap_put_tap_dev(struct tap_dev *tap)
901 {
902 dev_put(tap->dev);
903 }
904
905 static int tap_ioctl_set_queue(struct file *file, unsigned int flags)
906 {
907 struct tap_queue *q = file->private_data;
908 struct tap_dev *tap;
909 int ret;
910
911 tap = tap_get_tap_dev(q);
912 if (!tap)
913 return -EINVAL;
914
915 if (flags & IFF_ATTACH_QUEUE)
916 ret = tap_enable_queue(tap, file, q);
917 else if (flags & IFF_DETACH_QUEUE)
918 ret = tap_disable_queue(q);
919 else
920 ret = -EINVAL;
921
922 tap_put_tap_dev(tap);
923 return ret;
924 }
925
926 static int set_offload(struct tap_queue *q, unsigned long arg)
927 {
928 struct tap_dev *tap;
929 netdev_features_t features;
930 netdev_features_t feature_mask = 0;
931
932 tap = rtnl_dereference(q->tap);
933 if (!tap)
934 return -ENOLINK;
935
936 features = tap->dev->features;
937
938 if (arg & TUN_F_CSUM) {
939 feature_mask = NETIF_F_HW_CSUM;
940
941 if (arg & (TUN_F_TSO4 | TUN_F_TSO6)) {
942 if (arg & TUN_F_TSO_ECN)
943 feature_mask |= NETIF_F_TSO_ECN;
944 if (arg & TUN_F_TSO4)
945 feature_mask |= NETIF_F_TSO;
946 if (arg & TUN_F_TSO6)
947 feature_mask |= NETIF_F_TSO6;
948 }
949 }
950
951 /* tun/tap driver inverts the usage for TSO offloads, where
952 * setting the TSO bit means that the userspace wants to
953 * accept TSO frames and turning it off means that user space
954 * does not support TSO.
955 * For tap, we have to invert it to mean the same thing.
956 * When user space turns off TSO, we turn off GSO/LRO so that
957 * user-space will not receive TSO frames.
958 */
959 if (feature_mask & (NETIF_F_TSO | NETIF_F_TSO6))
960 features |= RX_OFFLOADS;
961 else
962 features &= ~RX_OFFLOADS;
963
964 /* tap_features are the same as features on tun/tap and
965 * reflect user expectations.
966 */
967 tap->tap_features = feature_mask;
968 if (tap->update_features)
969 tap->update_features(tap, features);
970
971 return 0;
972 }
973
974 /*
975 * provide compatibility with generic tun/tap interface
976 */
977 static long tap_ioctl(struct file *file, unsigned int cmd,
978 unsigned long arg)
979 {
980 struct tap_queue *q = file->private_data;
981 struct tap_dev *tap;
982 void __user *argp = (void __user *)arg;
983 struct ifreq __user *ifr = argp;
984 unsigned int __user *up = argp;
985 unsigned short u;
986 int __user *sp = argp;
987 struct sockaddr sa;
988 int s;
989 int ret;
990
991 switch (cmd) {
992 case TUNSETIFF:
993 /* ignore the name, just look at flags */
994 if (get_user(u, &ifr->ifr_flags))
995 return -EFAULT;
996
997 ret = 0;
998 if ((u & ~TAP_IFFEATURES) != (IFF_NO_PI | IFF_TAP))
999 ret = -EINVAL;
1000 else
1001 q->flags = (q->flags & ~TAP_IFFEATURES) | u;
1002
1003 return ret;
1004
1005 case TUNGETIFF:
1006 rtnl_lock();
1007 tap = tap_get_tap_dev(q);
1008 if (!tap) {
1009 rtnl_unlock();
1010 return -ENOLINK;
1011 }
1012
1013 ret = 0;
1014 u = q->flags;
1015 if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) ||
1016 put_user(u, &ifr->ifr_flags))
1017 ret = -EFAULT;
1018 tap_put_tap_dev(tap);
1019 rtnl_unlock();
1020 return ret;
1021
1022 case TUNSETQUEUE:
1023 if (get_user(u, &ifr->ifr_flags))
1024 return -EFAULT;
1025 rtnl_lock();
1026 ret = tap_ioctl_set_queue(file, u);
1027 rtnl_unlock();
1028 return ret;
1029
1030 case TUNGETFEATURES:
1031 if (put_user(IFF_TAP | IFF_NO_PI | TAP_IFFEATURES, up))
1032 return -EFAULT;
1033 return 0;
1034
1035 case TUNSETSNDBUF:
1036 if (get_user(s, sp))
1037 return -EFAULT;
1038 if (s <= 0)
1039 return -EINVAL;
1040
1041 q->sk.sk_sndbuf = s;
1042 return 0;
1043
1044 case TUNGETVNETHDRSZ:
1045 s = q->vnet_hdr_sz;
1046 if (put_user(s, sp))
1047 return -EFAULT;
1048 return 0;
1049
1050 case TUNSETVNETHDRSZ:
1051 if (get_user(s, sp))
1052 return -EFAULT;
1053 if (s < (int)sizeof(struct virtio_net_hdr))
1054 return -EINVAL;
1055
1056 q->vnet_hdr_sz = s;
1057 return 0;
1058
1059 case TUNGETVNETLE:
1060 s = !!(q->flags & TAP_VNET_LE);
1061 if (put_user(s, sp))
1062 return -EFAULT;
1063 return 0;
1064
1065 case TUNSETVNETLE:
1066 if (get_user(s, sp))
1067 return -EFAULT;
1068 if (s)
1069 q->flags |= TAP_VNET_LE;
1070 else
1071 q->flags &= ~TAP_VNET_LE;
1072 return 0;
1073
1074 case TUNGETVNETBE:
1075 return tap_get_vnet_be(q, sp);
1076
1077 case TUNSETVNETBE:
1078 return tap_set_vnet_be(q, sp);
1079
1080 case TUNSETOFFLOAD:
1081 /* let the user check for future flags */
1082 if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
1083 TUN_F_TSO_ECN | TUN_F_UFO))
1084 return -EINVAL;
1085
1086 rtnl_lock();
1087 ret = set_offload(q, arg);
1088 rtnl_unlock();
1089 return ret;
1090
1091 case SIOCGIFHWADDR:
1092 rtnl_lock();
1093 tap = tap_get_tap_dev(q);
1094 if (!tap) {
1095 rtnl_unlock();
1096 return -ENOLINK;
1097 }
1098 ret = 0;
1099 u = tap->dev->type;
1100 if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) ||
1101 copy_to_user(&ifr->ifr_hwaddr.sa_data, tap->dev->dev_addr, ETH_ALEN) ||
1102 put_user(u, &ifr->ifr_hwaddr.sa_family))
1103 ret = -EFAULT;
1104 tap_put_tap_dev(tap);
1105 rtnl_unlock();
1106 return ret;
1107
1108 case SIOCSIFHWADDR:
1109 if (copy_from_user(&sa, &ifr->ifr_hwaddr, sizeof(sa)))
1110 return -EFAULT;
1111 rtnl_lock();
1112 tap = tap_get_tap_dev(q);
1113 if (!tap) {
1114 rtnl_unlock();
1115 return -ENOLINK;
1116 }
1117 ret = dev_set_mac_address(tap->dev, &sa, NULL);
1118 tap_put_tap_dev(tap);
1119 rtnl_unlock();
1120 return ret;
1121
1122 default:
1123 return -EINVAL;
1124 }
1125 }
1126
1127 #ifdef CONFIG_COMPAT
1128 static long tap_compat_ioctl(struct file *file, unsigned int cmd,
1129 unsigned long arg)
1130 {
1131 return tap_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
1132 }
1133 #endif
1134
1135 static const struct file_operations tap_fops = {
1136 .owner = THIS_MODULE,
1137 .open = tap_open,
1138 .release = tap_release,
1139 .read_iter = tap_read_iter,
1140 .write_iter = tap_write_iter,
1141 .poll = tap_poll,
1142 .llseek = no_llseek,
1143 .unlocked_ioctl = tap_ioctl,
1144 #ifdef CONFIG_COMPAT
1145 .compat_ioctl = tap_compat_ioctl,
1146 #endif
1147 };
1148
1149 static int tap_get_user_xdp(struct tap_queue *q, struct xdp_buff *xdp)
1150 {
1151 struct tun_xdp_hdr *hdr = xdp->data_hard_start;
1152 struct virtio_net_hdr *gso = &hdr->gso;
1153 int buflen = hdr->buflen;
1154 int vnet_hdr_len = 0;
1155 struct tap_dev *tap;
1156 struct sk_buff *skb;
1157 int err, depth;
1158
1159 if (q->flags & IFF_VNET_HDR)
1160 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
1161
1162 skb = build_skb(xdp->data_hard_start, buflen);
1163 if (!skb) {
1164 err = -ENOMEM;
1165 goto err;
1166 }
1167
1168 skb_reserve(skb, xdp->data - xdp->data_hard_start);
1169 skb_put(skb, xdp->data_end - xdp->data);
1170
1171 skb_set_network_header(skb, ETH_HLEN);
1172 skb_reset_mac_header(skb);
1173 skb->protocol = eth_hdr(skb)->h_proto;
1174
1175 if (vnet_hdr_len) {
1176 err = virtio_net_hdr_to_skb(skb, gso, tap_is_little_endian(q));
1177 if (err)
1178 goto err_kfree;
1179 }
1180
1181 /* Move network header to the right position for VLAN tagged packets */
1182 if ((skb->protocol == htons(ETH_P_8021Q) ||
1183 skb->protocol == htons(ETH_P_8021AD)) &&
1184 __vlan_get_protocol(skb, skb->protocol, &depth) != 0)
1185 skb_set_network_header(skb, depth);
1186
1187 rcu_read_lock();
1188 tap = rcu_dereference(q->tap);
1189 if (tap) {
1190 skb->dev = tap->dev;
1191 skb_probe_transport_header(skb);
1192 dev_queue_xmit(skb);
1193 } else {
1194 kfree_skb(skb);
1195 }
1196 rcu_read_unlock();
1197
1198 return 0;
1199
1200 err_kfree:
1201 kfree_skb(skb);
1202 err:
1203 rcu_read_lock();
1204 tap = rcu_dereference(q->tap);
1205 if (tap && tap->count_tx_dropped)
1206 tap->count_tx_dropped(tap);
1207 rcu_read_unlock();
1208 return err;
1209 }
1210
1211 static int tap_sendmsg(struct socket *sock, struct msghdr *m,
1212 size_t total_len)
1213 {
1214 struct tap_queue *q = container_of(sock, struct tap_queue, sock);
1215 struct tun_msg_ctl *ctl = m->msg_control;
1216 struct xdp_buff *xdp;
1217 int i;
1218
1219 if (ctl && (ctl->type == TUN_MSG_PTR)) {
1220 for (i = 0; i < ctl->num; i++) {
1221 xdp = &((struct xdp_buff *)ctl->ptr)[i];
1222 tap_get_user_xdp(q, xdp);
1223 }
1224 return 0;
1225 }
1226
1227 return tap_get_user(q, ctl ? ctl->ptr : NULL, &m->msg_iter,
1228 m->msg_flags & MSG_DONTWAIT);
1229 }
1230
1231 static int tap_recvmsg(struct socket *sock, struct msghdr *m,
1232 size_t total_len, int flags)
1233 {
1234 struct tap_queue *q = container_of(sock, struct tap_queue, sock);
1235 struct sk_buff *skb = m->msg_control;
1236 int ret;
1237 if (flags & ~(MSG_DONTWAIT|MSG_TRUNC)) {
1238 kfree_skb(skb);
1239 return -EINVAL;
1240 }
1241 ret = tap_do_read(q, &m->msg_iter, flags & MSG_DONTWAIT, skb);
1242 if (ret > total_len) {
1243 m->msg_flags |= MSG_TRUNC;
1244 ret = flags & MSG_TRUNC ? ret : total_len;
1245 }
1246 return ret;
1247 }
1248
1249 static int tap_peek_len(struct socket *sock)
1250 {
1251 struct tap_queue *q = container_of(sock, struct tap_queue,
1252 sock);
1253 return PTR_RING_PEEK_CALL(&q->ring, __skb_array_len_with_tag);
1254 }
1255
1256 /* Ops structure to mimic raw sockets with tun */
1257 static const struct proto_ops tap_socket_ops = {
1258 .sendmsg = tap_sendmsg,
1259 .recvmsg = tap_recvmsg,
1260 .peek_len = tap_peek_len,
1261 };
1262
1263 /* Get an underlying socket object from tun file. Returns error unless file is
1264 * attached to a device. The returned object works like a packet socket, it
1265 * can be used for sock_sendmsg/sock_recvmsg. The caller is responsible for
1266 * holding a reference to the file for as long as the socket is in use. */
1267 struct socket *tap_get_socket(struct file *file)
1268 {
1269 struct tap_queue *q;
1270 if (file->f_op != &tap_fops)
1271 return ERR_PTR(-EINVAL);
1272 q = file->private_data;
1273 if (!q)
1274 return ERR_PTR(-EBADFD);
1275 return &q->sock;
1276 }
1277 EXPORT_SYMBOL_GPL(tap_get_socket);
1278
1279 struct ptr_ring *tap_get_ptr_ring(struct file *file)
1280 {
1281 struct tap_queue *q;
1282
1283 if (file->f_op != &tap_fops)
1284 return ERR_PTR(-EINVAL);
1285 q = file->private_data;
1286 if (!q)
1287 return ERR_PTR(-EBADFD);
1288 return &q->ring;
1289 }
1290 EXPORT_SYMBOL_GPL(tap_get_ptr_ring);
1291
1292 int tap_queue_resize(struct tap_dev *tap)
1293 {
1294 struct net_device *dev = tap->dev;
1295 struct tap_queue *q;
1296 struct ptr_ring **rings;
1297 int n = tap->numqueues;
1298 int ret, i = 0;
1299
1300 rings = kmalloc_array(n, sizeof(*rings), GFP_KERNEL);
1301 if (!rings)
1302 return -ENOMEM;
1303
1304 list_for_each_entry(q, &tap->queue_list, next)
1305 rings[i++] = &q->ring;
1306
1307 ret = ptr_ring_resize_multiple(rings, n,
1308 dev->tx_queue_len, GFP_KERNEL,
1309 __skb_array_destroy_skb);
1310
1311 kfree(rings);
1312 return ret;
1313 }
1314 EXPORT_SYMBOL_GPL(tap_queue_resize);
1315
1316 static int tap_list_add(dev_t major, const char *device_name)
1317 {
1318 struct major_info *tap_major;
1319
1320 tap_major = kzalloc(sizeof(*tap_major), GFP_ATOMIC);
1321 if (!tap_major)
1322 return -ENOMEM;
1323
1324 tap_major->major = MAJOR(major);
1325
1326 idr_init(&tap_major->minor_idr);
1327 spin_lock_init(&tap_major->minor_lock);
1328
1329 tap_major->device_name = device_name;
1330
1331 list_add_tail_rcu(&tap_major->next, &major_list);
1332 return 0;
1333 }
1334
1335 int tap_create_cdev(struct cdev *tap_cdev, dev_t *tap_major,
1336 const char *device_name, struct module *module)
1337 {
1338 int err;
1339
1340 err = alloc_chrdev_region(tap_major, 0, TAP_NUM_DEVS, device_name);
1341 if (err)
1342 goto out1;
1343
1344 cdev_init(tap_cdev, &tap_fops);
1345 tap_cdev->owner = module;
1346 err = cdev_add(tap_cdev, *tap_major, TAP_NUM_DEVS);
1347 if (err)
1348 goto out2;
1349
1350 err = tap_list_add(*tap_major, device_name);
1351 if (err)
1352 goto out3;
1353
1354 return 0;
1355
1356 out3:
1357 cdev_del(tap_cdev);
1358 out2:
1359 unregister_chrdev_region(*tap_major, TAP_NUM_DEVS);
1360 out1:
1361 return err;
1362 }
1363 EXPORT_SYMBOL_GPL(tap_create_cdev);
1364
1365 void tap_destroy_cdev(dev_t major, struct cdev *tap_cdev)
1366 {
1367 struct major_info *tap_major, *tmp;
1368
1369 cdev_del(tap_cdev);
1370 unregister_chrdev_region(major, TAP_NUM_DEVS);
1371 list_for_each_entry_safe(tap_major, tmp, &major_list, next) {
1372 if (tap_major->major == MAJOR(major)) {
1373 idr_destroy(&tap_major->minor_idr);
1374 list_del_rcu(&tap_major->next);
1375 kfree_rcu(tap_major, rcu);
1376 }
1377 }
1378 }
1379 EXPORT_SYMBOL_GPL(tap_destroy_cdev);
1380
1381 MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>");
1382 MODULE_AUTHOR("Sainath Grandhi <sainath.grandhi@intel.com>");
1383 MODULE_LICENSE("GPL");
Linux with added FPC-III support