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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/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
33static 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
39static 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
49static 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
64static inline bool tap_legacy_is_little_endian(struct tap_queue *q)
65{
66 return virtio_legacy_is_little_endian();
67}
68
69static long tap_get_vnet_be(struct tap_queue *q, int __user *argp)
70{
71 return -EINVAL;
72}
73
74static 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
80static 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
86static 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
91static 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
96static 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
104static LIST_HEAD(major_list);
105
106struct 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
117static 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
122static 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
144static 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++;
160out:
161 return err;
162}
163
164/* Requires RTNL */
165static 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
187static 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 */
222static 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 */
252static 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
287single:
288 queue = rcu_dereference(tap->taps[0]);
289out:
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 */
298void 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}
316EXPORT_SYMBOL_GPL(tap_del_queues);
317
318rx_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
380wake_up:
381 wake_up_interruptible_poll(sk_sleep(&q->sk), EPOLLIN | EPOLLRDNORM | EPOLLRDBAND);
382 return RX_HANDLER_CONSUMED;
383
384drop:
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}
391EXPORT_SYMBOL_GPL(tap_handle_frame);
392
393static 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
405int 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
427unlock:
428 rcu_read_unlock();
429 return retval < 0 ? retval : 0;
430}
431EXPORT_SYMBOL_GPL(tap_get_minor);
432
433void 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
450unlock:
451 rcu_read_unlock();
452}
453EXPORT_SYMBOL_GPL(tap_free_minor);
454
455static 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
476unlock:
477 rcu_read_unlock();
478 return tap;
479}
480
481static 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
494static 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
501static 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 init_waitqueue_head(&q->sock.wq.wait);
524 q->sock.type = SOCK_RAW;
525 q->sock.state = SS_CONNECTED;
526 q->sock.file = file;
527 q->sock.ops = &tap_socket_ops;
528 sock_init_data(&q->sock, &q->sk);
529 q->sk.sk_write_space = tap_sock_write_space;
530 q->sk.sk_destruct = tap_sock_destruct;
531 q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP;
532 q->vnet_hdr_sz = sizeof(struct virtio_net_hdr);
533
534 /*
535 * so far only KVM virtio_net uses tap, enable zero copy between
536 * guest kernel and host kernel when lower device supports zerocopy
537 *
538 * The macvlan supports zerocopy iff the lower device supports zero
539 * copy so we don't have to look at the lower device directly.
540 */
541 if ((tap->dev->features & NETIF_F_HIGHDMA) && (tap->dev->features & NETIF_F_SG))
542 sock_set_flag(&q->sk, SOCK_ZEROCOPY);
543
544 err = tap_set_queue(tap, file, q);
545 if (err) {
546 /* tap_sock_destruct() will take care of freeing ptr_ring */
547 goto err_put;
548 }
549
550 dev_put(tap->dev);
551
552 rtnl_unlock();
553 return err;
554
555err_put:
556 sock_put(&q->sk);
557err:
558 if (tap)
559 dev_put(tap->dev);
560
561 rtnl_unlock();
562 return err;
563}
564
565static int tap_release(struct inode *inode, struct file *file)
566{
567 struct tap_queue *q = file->private_data;
568 tap_put_queue(q);
569 return 0;
570}
571
572static __poll_t tap_poll(struct file *file, poll_table *wait)
573{
574 struct tap_queue *q = file->private_data;
575 __poll_t mask = EPOLLERR;
576
577 if (!q)
578 goto out;
579
580 mask = 0;
581 poll_wait(file, &q->sock.wq.wait, wait);
582
583 if (!ptr_ring_empty(&q->ring))
584 mask |= EPOLLIN | EPOLLRDNORM;
585
586 if (sock_writeable(&q->sk) ||
587 (!test_and_set_bit(SOCKWQ_ASYNC_NOSPACE, &q->sock.flags) &&
588 sock_writeable(&q->sk)))
589 mask |= EPOLLOUT | EPOLLWRNORM;
590
591out:
592 return mask;
593}
594
595static inline struct sk_buff *tap_alloc_skb(struct sock *sk, size_t prepad,
596 size_t len, size_t linear,
597 int noblock, int *err)
598{
599 struct sk_buff *skb;
600
601 /* Under a page? Don't bother with paged skb. */
602 if (prepad + len < PAGE_SIZE || !linear)
603 linear = len;
604
605 skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
606 err, 0);
607 if (!skb)
608 return NULL;
609
610 skb_reserve(skb, prepad);
611 skb_put(skb, linear);
612 skb->data_len = len - linear;
613 skb->len += len - linear;
614
615 return skb;
616}
617
618/* Neighbour code has some assumptions on HH_DATA_MOD alignment */
619#define TAP_RESERVE HH_DATA_OFF(ETH_HLEN)
620
621/* Get packet from user space buffer */
622static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,
623 struct iov_iter *from, int noblock)
624{
625 int good_linear = SKB_MAX_HEAD(TAP_RESERVE);
626 struct sk_buff *skb;
627 struct tap_dev *tap;
628 unsigned long total_len = iov_iter_count(from);
629 unsigned long len = total_len;
630 int err;
631 struct virtio_net_hdr vnet_hdr = { 0 };
632 int vnet_hdr_len = 0;
633 int copylen = 0;
634 int depth;
635 bool zerocopy = false;
636 size_t linear;
637
638 if (q->flags & IFF_VNET_HDR) {
639 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
640
641 err = -EINVAL;
642 if (len < vnet_hdr_len)
643 goto err;
644 len -= vnet_hdr_len;
645
646 err = -EFAULT;
647 if (!copy_from_iter_full(&vnet_hdr, sizeof(vnet_hdr), from))
648 goto err;
649 iov_iter_advance(from, vnet_hdr_len - sizeof(vnet_hdr));
650 if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
651 tap16_to_cpu(q, vnet_hdr.csum_start) +
652 tap16_to_cpu(q, vnet_hdr.csum_offset) + 2 >
653 tap16_to_cpu(q, vnet_hdr.hdr_len))
654 vnet_hdr.hdr_len = cpu_to_tap16(q,
655 tap16_to_cpu(q, vnet_hdr.csum_start) +
656 tap16_to_cpu(q, vnet_hdr.csum_offset) + 2);
657 err = -EINVAL;
658 if (tap16_to_cpu(q, vnet_hdr.hdr_len) > len)
659 goto err;
660 }
661
662 err = -EINVAL;
663 if (unlikely(len < ETH_HLEN))
664 goto err;
665
666 if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) {
667 struct iov_iter i;
668
669 copylen = vnet_hdr.hdr_len ?
670 tap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN;
671 if (copylen > good_linear)
672 copylen = good_linear;
673 else if (copylen < ETH_HLEN)
674 copylen = ETH_HLEN;
675 linear = copylen;
676 i = *from;
677 iov_iter_advance(&i, copylen);
678 if (iov_iter_npages(&i, INT_MAX) <= MAX_SKB_FRAGS)
679 zerocopy = true;
680 }
681
682 if (!zerocopy) {
683 copylen = len;
684 linear = tap16_to_cpu(q, vnet_hdr.hdr_len);
685 if (linear > good_linear)
686 linear = good_linear;
687 else if (linear < ETH_HLEN)
688 linear = ETH_HLEN;
689 }
690
691 skb = tap_alloc_skb(&q->sk, TAP_RESERVE, copylen,
692 linear, noblock, &err);
693 if (!skb)
694 goto err;
695
696 if (zerocopy)
697 err = zerocopy_sg_from_iter(skb, from);
698 else
699 err = skb_copy_datagram_from_iter(skb, 0, from, len);
700
701 if (err)
702 goto err_kfree;
703
704 skb_set_network_header(skb, ETH_HLEN);
705 skb_reset_mac_header(skb);
706 skb->protocol = eth_hdr(skb)->h_proto;
707
708 if (vnet_hdr_len) {
709 err = virtio_net_hdr_to_skb(skb, &vnet_hdr,
710 tap_is_little_endian(q));
711 if (err)
712 goto err_kfree;
713 }
714
715 skb_probe_transport_header(skb);
716
717 /* Move network header to the right position for VLAN tagged packets */
718 if ((skb->protocol == htons(ETH_P_8021Q) ||
719 skb->protocol == htons(ETH_P_8021AD)) &&
720 __vlan_get_protocol(skb, skb->protocol, &depth) != 0)
721 skb_set_network_header(skb, depth);
722
723 rcu_read_lock();
724 tap = rcu_dereference(q->tap);
725 /* copy skb_ubuf_info for callback when skb has no error */
726 if (zerocopy) {
727 skb_shinfo(skb)->destructor_arg = msg_control;
728 skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
729 skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
730 } else if (msg_control) {
731 struct ubuf_info *uarg = msg_control;
732 uarg->callback(uarg, false);
733 }
734
735 if (tap) {
736 skb->dev = tap->dev;
737 dev_queue_xmit(skb);
738 } else {
739 kfree_skb(skb);
740 }
741 rcu_read_unlock();
742
743 return total_len;
744
745err_kfree:
746 kfree_skb(skb);
747
748err:
749 rcu_read_lock();
750 tap = rcu_dereference(q->tap);
751 if (tap && tap->count_tx_dropped)
752 tap->count_tx_dropped(tap);
753 rcu_read_unlock();
754
755 return err;
756}
757
758static ssize_t tap_write_iter(struct kiocb *iocb, struct iov_iter *from)
759{
760 struct file *file = iocb->ki_filp;
761 struct tap_queue *q = file->private_data;
762
763 return tap_get_user(q, NULL, from, file->f_flags & O_NONBLOCK);
764}
765
766/* Put packet to the user space buffer */
767static ssize_t tap_put_user(struct tap_queue *q,
768 const struct sk_buff *skb,
769 struct iov_iter *iter)
770{
771 int ret;
772 int vnet_hdr_len = 0;
773 int vlan_offset = 0;
774 int total;
775
776 if (q->flags & IFF_VNET_HDR) {
777 int vlan_hlen = skb_vlan_tag_present(skb) ? VLAN_HLEN : 0;
778 struct virtio_net_hdr vnet_hdr;
779
780 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
781 if (iov_iter_count(iter) < vnet_hdr_len)
782 return -EINVAL;
783
784 if (virtio_net_hdr_from_skb(skb, &vnet_hdr,
785 tap_is_little_endian(q), true,
786 vlan_hlen))
787 BUG();
788
789 if (copy_to_iter(&vnet_hdr, sizeof(vnet_hdr), iter) !=
790 sizeof(vnet_hdr))
791 return -EFAULT;
792
793 iov_iter_advance(iter, vnet_hdr_len - sizeof(vnet_hdr));
794 }
795 total = vnet_hdr_len;
796 total += skb->len;
797
798 if (skb_vlan_tag_present(skb)) {
799 struct {
800 __be16 h_vlan_proto;
801 __be16 h_vlan_TCI;
802 } veth;
803 veth.h_vlan_proto = skb->vlan_proto;
804 veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
805
806 vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
807 total += VLAN_HLEN;
808
809 ret = skb_copy_datagram_iter(skb, 0, iter, vlan_offset);
810 if (ret || !iov_iter_count(iter))
811 goto done;
812
813 ret = copy_to_iter(&veth, sizeof(veth), iter);
814 if (ret != sizeof(veth) || !iov_iter_count(iter))
815 goto done;
816 }
817
818 ret = skb_copy_datagram_iter(skb, vlan_offset, iter,
819 skb->len - vlan_offset);
820
821done:
822 return ret ? ret : total;
823}
824
825static ssize_t tap_do_read(struct tap_queue *q,
826 struct iov_iter *to,
827 int noblock, struct sk_buff *skb)
828{
829 DEFINE_WAIT(wait);
830 ssize_t ret = 0;
831
832 if (!iov_iter_count(to)) {
833 kfree_skb(skb);
834 return 0;
835 }
836
837 if (skb)
838 goto put;
839
840 while (1) {
841 if (!noblock)
842 prepare_to_wait(sk_sleep(&q->sk), &wait,
843 TASK_INTERRUPTIBLE);
844
845 /* Read frames from the queue */
846 skb = ptr_ring_consume(&q->ring);
847 if (skb)
848 break;
849 if (noblock) {
850 ret = -EAGAIN;
851 break;
852 }
853 if (signal_pending(current)) {
854 ret = -ERESTARTSYS;
855 break;
856 }
857 /* Nothing to read, let's sleep */
858 schedule();
859 }
860 if (!noblock)
861 finish_wait(sk_sleep(&q->sk), &wait);
862
863put:
864 if (skb) {
865 ret = tap_put_user(q, skb, to);
866 if (unlikely(ret < 0))
867 kfree_skb(skb);
868 else
869 consume_skb(skb);
870 }
871 return ret;
872}
873
874static ssize_t tap_read_iter(struct kiocb *iocb, struct iov_iter *to)
875{
876 struct file *file = iocb->ki_filp;
877 struct tap_queue *q = file->private_data;
878 ssize_t len = iov_iter_count(to), ret;
879
880 ret = tap_do_read(q, to, file->f_flags & O_NONBLOCK, NULL);
881 ret = min_t(ssize_t, ret, len);
882 if (ret > 0)
883 iocb->ki_pos = ret;
884 return ret;
885}
886
887static struct tap_dev *tap_get_tap_dev(struct tap_queue *q)
888{
889 struct tap_dev *tap;
890
891 ASSERT_RTNL();
892 tap = rtnl_dereference(q->tap);
893 if (tap)
894 dev_hold(tap->dev);
895
896 return tap;
897}
898
899static void tap_put_tap_dev(struct tap_dev *tap)
900{
901 dev_put(tap->dev);
902}
903
904static int tap_ioctl_set_queue(struct file *file, unsigned int flags)
905{
906 struct tap_queue *q = file->private_data;
907 struct tap_dev *tap;
908 int ret;
909
910 tap = tap_get_tap_dev(q);
911 if (!tap)
912 return -EINVAL;
913
914 if (flags & IFF_ATTACH_QUEUE)
915 ret = tap_enable_queue(tap, file, q);
916 else if (flags & IFF_DETACH_QUEUE)
917 ret = tap_disable_queue(q);
918 else
919 ret = -EINVAL;
920
921 tap_put_tap_dev(tap);
922 return ret;
923}
924
925static int set_offload(struct tap_queue *q, unsigned long arg)
926{
927 struct tap_dev *tap;
928 netdev_features_t features;
929 netdev_features_t feature_mask = 0;
930
931 tap = rtnl_dereference(q->tap);
932 if (!tap)
933 return -ENOLINK;
934
935 features = tap->dev->features;
936
937 if (arg & TUN_F_CSUM) {
938 feature_mask = NETIF_F_HW_CSUM;
939
940 if (arg & (TUN_F_TSO4 | TUN_F_TSO6)) {
941 if (arg & TUN_F_TSO_ECN)
942 feature_mask |= NETIF_F_TSO_ECN;
943 if (arg & TUN_F_TSO4)
944 feature_mask |= NETIF_F_TSO;
945 if (arg & TUN_F_TSO6)
946 feature_mask |= NETIF_F_TSO6;
947 }
948 }
949
950 /* tun/tap driver inverts the usage for TSO offloads, where
951 * setting the TSO bit means that the userspace wants to
952 * accept TSO frames and turning it off means that user space
953 * does not support TSO.
954 * For tap, we have to invert it to mean the same thing.
955 * When user space turns off TSO, we turn off GSO/LRO so that
956 * user-space will not receive TSO frames.
957 */
958 if (feature_mask & (NETIF_F_TSO | NETIF_F_TSO6))
959 features |= RX_OFFLOADS;
960 else
961 features &= ~RX_OFFLOADS;
962
963 /* tap_features are the same as features on tun/tap and
964 * reflect user expectations.
965 */
966 tap->tap_features = feature_mask;
967 if (tap->update_features)
968 tap->update_features(tap, features);
969
970 return 0;
971}
972
973/*
974 * provide compatibility with generic tun/tap interface
975 */
976static long tap_ioctl(struct file *file, unsigned int cmd,
977 unsigned long arg)
978{
979 struct tap_queue *q = file->private_data;
980 struct tap_dev *tap;
981 void __user *argp = (void __user *)arg;
982 struct ifreq __user *ifr = argp;
983 unsigned int __user *up = argp;
984 unsigned short u;
985 int __user *sp = argp;
986 struct sockaddr sa;
987 int s;
988 int ret;
989
990 switch (cmd) {
991 case TUNSETIFF:
992 /* ignore the name, just look at flags */
993 if (get_user(u, &ifr->ifr_flags))
994 return -EFAULT;
995
996 ret = 0;
997 if ((u & ~TAP_IFFEATURES) != (IFF_NO_PI | IFF_TAP))
998 ret = -EINVAL;
999 else
1000 q->flags = (q->flags & ~TAP_IFFEATURES) | u;
1001
1002 return ret;
1003
1004 case TUNGETIFF:
1005 rtnl_lock();
1006 tap = tap_get_tap_dev(q);
1007 if (!tap) {
1008 rtnl_unlock();
1009 return -ENOLINK;
1010 }
1011
1012 ret = 0;
1013 u = q->flags;
1014 if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) ||
1015 put_user(u, &ifr->ifr_flags))
1016 ret = -EFAULT;
1017 tap_put_tap_dev(tap);
1018 rtnl_unlock();
1019 return ret;
1020
1021 case TUNSETQUEUE:
1022 if (get_user(u, &ifr->ifr_flags))
1023 return -EFAULT;
1024 rtnl_lock();
1025 ret = tap_ioctl_set_queue(file, u);
1026 rtnl_unlock();
1027 return ret;
1028
1029 case TUNGETFEATURES:
1030 if (put_user(IFF_TAP | IFF_NO_PI | TAP_IFFEATURES, up))
1031 return -EFAULT;
1032 return 0;
1033
1034 case TUNSETSNDBUF:
1035 if (get_user(s, sp))
1036 return -EFAULT;
1037 if (s <= 0)
1038 return -EINVAL;
1039
1040 q->sk.sk_sndbuf = s;
1041 return 0;
1042
1043 case TUNGETVNETHDRSZ:
1044 s = q->vnet_hdr_sz;
1045 if (put_user(s, sp))
1046 return -EFAULT;
1047 return 0;
1048
1049 case TUNSETVNETHDRSZ:
1050 if (get_user(s, sp))
1051 return -EFAULT;
1052 if (s < (int)sizeof(struct virtio_net_hdr))
1053 return -EINVAL;
1054
1055 q->vnet_hdr_sz = s;
1056 return 0;
1057
1058 case TUNGETVNETLE:
1059 s = !!(q->flags & TAP_VNET_LE);
1060 if (put_user(s, sp))
1061 return -EFAULT;
1062 return 0;
1063
1064 case TUNSETVNETLE:
1065 if (get_user(s, sp))
1066 return -EFAULT;
1067 if (s)
1068 q->flags |= TAP_VNET_LE;
1069 else
1070 q->flags &= ~TAP_VNET_LE;
1071 return 0;
1072
1073 case TUNGETVNETBE:
1074 return tap_get_vnet_be(q, sp);
1075
1076 case TUNSETVNETBE:
1077 return tap_set_vnet_be(q, sp);
1078
1079 case TUNSETOFFLOAD:
1080 /* let the user check for future flags */
1081 if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
1082 TUN_F_TSO_ECN | TUN_F_UFO))
1083 return -EINVAL;
1084
1085 rtnl_lock();
1086 ret = set_offload(q, arg);
1087 rtnl_unlock();
1088 return ret;
1089
1090 case SIOCGIFHWADDR:
1091 rtnl_lock();
1092 tap = tap_get_tap_dev(q);
1093 if (!tap) {
1094 rtnl_unlock();
1095 return -ENOLINK;
1096 }
1097 ret = 0;
1098 u = tap->dev->type;
1099 if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) ||
1100 copy_to_user(&ifr->ifr_hwaddr.sa_data, tap->dev->dev_addr, ETH_ALEN) ||
1101 put_user(u, &ifr->ifr_hwaddr.sa_family))
1102 ret = -EFAULT;
1103 tap_put_tap_dev(tap);
1104 rtnl_unlock();
1105 return ret;
1106
1107 case SIOCSIFHWADDR:
1108 if (copy_from_user(&sa, &ifr->ifr_hwaddr, sizeof(sa)))
1109 return -EFAULT;
1110 rtnl_lock();
1111 tap = tap_get_tap_dev(q);
1112 if (!tap) {
1113 rtnl_unlock();
1114 return -ENOLINK;
1115 }
1116 ret = dev_set_mac_address(tap->dev, &sa, NULL);
1117 tap_put_tap_dev(tap);
1118 rtnl_unlock();
1119 return ret;
1120
1121 default:
1122 return -EINVAL;
1123 }
1124}
1125
1126#ifdef CONFIG_COMPAT
1127static long tap_compat_ioctl(struct file *file, unsigned int cmd,
1128 unsigned long arg)
1129{
1130 return tap_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
1131}
1132#endif
1133
1134static const struct file_operations tap_fops = {
1135 .owner = THIS_MODULE,
1136 .open = tap_open,
1137 .release = tap_release,
1138 .read_iter = tap_read_iter,
1139 .write_iter = tap_write_iter,
1140 .poll = tap_poll,
1141 .llseek = no_llseek,
1142 .unlocked_ioctl = tap_ioctl,
1143#ifdef CONFIG_COMPAT
1144 .compat_ioctl = tap_compat_ioctl,
1145#endif
1146};
1147
1148static int tap_get_user_xdp(struct tap_queue *q, struct xdp_buff *xdp)
1149{
1150 struct tun_xdp_hdr *hdr = xdp->data_hard_start;
1151 struct virtio_net_hdr *gso = &hdr->gso;
1152 int buflen = hdr->buflen;
1153 int vnet_hdr_len = 0;
1154 struct tap_dev *tap;
1155 struct sk_buff *skb;
1156 int err, depth;
1157
1158 if (q->flags & IFF_VNET_HDR)
1159 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
1160
1161 skb = build_skb(xdp->data_hard_start, buflen);
1162 if (!skb) {
1163 err = -ENOMEM;
1164 goto err;
1165 }
1166
1167 skb_reserve(skb, xdp->data - xdp->data_hard_start);
1168 skb_put(skb, xdp->data_end - xdp->data);
1169
1170 skb_set_network_header(skb, ETH_HLEN);
1171 skb_reset_mac_header(skb);
1172 skb->protocol = eth_hdr(skb)->h_proto;
1173
1174 if (vnet_hdr_len) {
1175 err = virtio_net_hdr_to_skb(skb, gso, tap_is_little_endian(q));
1176 if (err)
1177 goto err_kfree;
1178 }
1179
1180 /* Move network header to the right position for VLAN tagged packets */
1181 if ((skb->protocol == htons(ETH_P_8021Q) ||
1182 skb->protocol == htons(ETH_P_8021AD)) &&
1183 __vlan_get_protocol(skb, skb->protocol, &depth) != 0)
1184 skb_set_network_header(skb, depth);
1185
1186 rcu_read_lock();
1187 tap = rcu_dereference(q->tap);
1188 if (tap) {
1189 skb->dev = tap->dev;
1190 skb_probe_transport_header(skb);
1191 dev_queue_xmit(skb);
1192 } else {
1193 kfree_skb(skb);
1194 }
1195 rcu_read_unlock();
1196
1197 return 0;
1198
1199err_kfree:
1200 kfree_skb(skb);
1201err:
1202 rcu_read_lock();
1203 tap = rcu_dereference(q->tap);
1204 if (tap && tap->count_tx_dropped)
1205 tap->count_tx_dropped(tap);
1206 rcu_read_unlock();
1207 return err;
1208}
1209
1210static int tap_sendmsg(struct socket *sock, struct msghdr *m,
1211 size_t total_len)
1212{
1213 struct tap_queue *q = container_of(sock, struct tap_queue, sock);
1214 struct tun_msg_ctl *ctl = m->msg_control;
1215 struct xdp_buff *xdp;
1216 int i;
1217
1218 if (ctl && (ctl->type == TUN_MSG_PTR)) {
1219 for (i = 0; i < ctl->num; i++) {
1220 xdp = &((struct xdp_buff *)ctl->ptr)[i];
1221 tap_get_user_xdp(q, xdp);
1222 }
1223 return 0;
1224 }
1225
1226 return tap_get_user(q, ctl ? ctl->ptr : NULL, &m->msg_iter,
1227 m->msg_flags & MSG_DONTWAIT);
1228}
1229
1230static int tap_recvmsg(struct socket *sock, struct msghdr *m,
1231 size_t total_len, int flags)
1232{
1233 struct tap_queue *q = container_of(sock, struct tap_queue, sock);
1234 struct sk_buff *skb = m->msg_control;
1235 int ret;
1236 if (flags & ~(MSG_DONTWAIT|MSG_TRUNC)) {
1237 kfree_skb(skb);
1238 return -EINVAL;
1239 }
1240 ret = tap_do_read(q, &m->msg_iter, flags & MSG_DONTWAIT, skb);
1241 if (ret > total_len) {
1242 m->msg_flags |= MSG_TRUNC;
1243 ret = flags & MSG_TRUNC ? ret : total_len;
1244 }
1245 return ret;
1246}
1247
1248static int tap_peek_len(struct socket *sock)
1249{
1250 struct tap_queue *q = container_of(sock, struct tap_queue,
1251 sock);
1252 return PTR_RING_PEEK_CALL(&q->ring, __skb_array_len_with_tag);
1253}
1254
1255/* Ops structure to mimic raw sockets with tun */
1256static const struct proto_ops tap_socket_ops = {
1257 .sendmsg = tap_sendmsg,
1258 .recvmsg = tap_recvmsg,
1259 .peek_len = tap_peek_len,
1260};
1261
1262/* Get an underlying socket object from tun file. Returns error unless file is
1263 * attached to a device. The returned object works like a packet socket, it
1264 * can be used for sock_sendmsg/sock_recvmsg. The caller is responsible for
1265 * holding a reference to the file for as long as the socket is in use. */
1266struct socket *tap_get_socket(struct file *file)
1267{
1268 struct tap_queue *q;
1269 if (file->f_op != &tap_fops)
1270 return ERR_PTR(-EINVAL);
1271 q = file->private_data;
1272 if (!q)
1273 return ERR_PTR(-EBADFD);
1274 return &q->sock;
1275}
1276EXPORT_SYMBOL_GPL(tap_get_socket);
1277
1278struct ptr_ring *tap_get_ptr_ring(struct file *file)
1279{
1280 struct tap_queue *q;
1281
1282 if (file->f_op != &tap_fops)
1283 return ERR_PTR(-EINVAL);
1284 q = file->private_data;
1285 if (!q)
1286 return ERR_PTR(-EBADFD);
1287 return &q->ring;
1288}
1289EXPORT_SYMBOL_GPL(tap_get_ptr_ring);
1290
1291int tap_queue_resize(struct tap_dev *tap)
1292{
1293 struct net_device *dev = tap->dev;
1294 struct tap_queue *q;
1295 struct ptr_ring **rings;
1296 int n = tap->numqueues;
1297 int ret, i = 0;
1298
1299 rings = kmalloc_array(n, sizeof(*rings), GFP_KERNEL);
1300 if (!rings)
1301 return -ENOMEM;
1302
1303 list_for_each_entry(q, &tap->queue_list, next)
1304 rings[i++] = &q->ring;
1305
1306 ret = ptr_ring_resize_multiple(rings, n,
1307 dev->tx_queue_len, GFP_KERNEL,
1308 __skb_array_destroy_skb);
1309
1310 kfree(rings);
1311 return ret;
1312}
1313EXPORT_SYMBOL_GPL(tap_queue_resize);
1314
1315static int tap_list_add(dev_t major, const char *device_name)
1316{
1317 struct major_info *tap_major;
1318
1319 tap_major = kzalloc(sizeof(*tap_major), GFP_ATOMIC);
1320 if (!tap_major)
1321 return -ENOMEM;
1322
1323 tap_major->major = MAJOR(major);
1324
1325 idr_init(&tap_major->minor_idr);
1326 spin_lock_init(&tap_major->minor_lock);
1327
1328 tap_major->device_name = device_name;
1329
1330 list_add_tail_rcu(&tap_major->next, &major_list);
1331 return 0;
1332}
1333
1334int tap_create_cdev(struct cdev *tap_cdev, dev_t *tap_major,
1335 const char *device_name, struct module *module)
1336{
1337 int err;
1338
1339 err = alloc_chrdev_region(tap_major, 0, TAP_NUM_DEVS, device_name);
1340 if (err)
1341 goto out1;
1342
1343 cdev_init(tap_cdev, &tap_fops);
1344 tap_cdev->owner = module;
1345 err = cdev_add(tap_cdev, *tap_major, TAP_NUM_DEVS);
1346 if (err)
1347 goto out2;
1348
1349 err = tap_list_add(*tap_major, device_name);
1350 if (err)
1351 goto out3;
1352
1353 return 0;
1354
1355out3:
1356 cdev_del(tap_cdev);
1357out2:
1358 unregister_chrdev_region(*tap_major, TAP_NUM_DEVS);
1359out1:
1360 return err;
1361}
1362EXPORT_SYMBOL_GPL(tap_create_cdev);
1363
1364void tap_destroy_cdev(dev_t major, struct cdev *tap_cdev)
1365{
1366 struct major_info *tap_major, *tmp;
1367
1368 cdev_del(tap_cdev);
1369 unregister_chrdev_region(major, TAP_NUM_DEVS);
1370 list_for_each_entry_safe(tap_major, tmp, &major_list, next) {
1371 if (tap_major->major == MAJOR(major)) {
1372 idr_destroy(&tap_major->minor_idr);
1373 list_del_rcu(&tap_major->next);
1374 kfree_rcu(tap_major, rcu);
1375 }
1376 }
1377}
1378EXPORT_SYMBOL_GPL(tap_destroy_cdev);
1379
1380MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>");
1381MODULE_AUTHOR("Sainath Grandhi <sainath.grandhi@intel.com>");
1382MODULE_LICENSE("GPL");