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