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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 struct sk_buff *next;
345
346 if (IS_ERR(segs))
347 goto drop;
348
349 if (!segs) {
350 if (ptr_ring_produce(&q->ring, skb))
351 goto drop;
352 goto wake_up;
353 }
354
355 consume_skb(skb);
356 skb_list_walk_safe(segs, skb, next) {
357 skb_mark_not_on_list(skb);
358 if (ptr_ring_produce(&q->ring, skb)) {
359 kfree_skb(skb);
360 kfree_skb_list(next);
361 break;
362 }
363 }
364 } else {
365 /* If we receive a partial checksum and the tap side
366 * doesn't support checksum offload, compute the checksum.
367 * Note: it doesn't matter which checksum feature to
368 * check, we either support them all or none.
369 */
370 if (skb->ip_summed == CHECKSUM_PARTIAL &&
371 !(features & NETIF_F_CSUM_MASK) &&
372 skb_checksum_help(skb))
373 goto drop;
374 if (ptr_ring_produce(&q->ring, skb))
375 goto drop;
376 }
377
378wake_up:
379 wake_up_interruptible_poll(sk_sleep(&q->sk), EPOLLIN | EPOLLRDNORM | EPOLLRDBAND);
380 return RX_HANDLER_CONSUMED;
381
382drop:
383 /* Count errors/drops only here, thus don't care about args. */
384 if (tap->count_rx_dropped)
385 tap->count_rx_dropped(tap);
386 kfree_skb(skb);
387 return RX_HANDLER_CONSUMED;
388}
389EXPORT_SYMBOL_GPL(tap_handle_frame);
390
391static struct major_info *tap_get_major(int major)
392{
393 struct major_info *tap_major;
394
395 list_for_each_entry_rcu(tap_major, &major_list, next) {
396 if (tap_major->major == major)
397 return tap_major;
398 }
399
400 return NULL;
401}
402
403int tap_get_minor(dev_t major, struct tap_dev *tap)
404{
405 int retval = -ENOMEM;
406 struct major_info *tap_major;
407
408 rcu_read_lock();
409 tap_major = tap_get_major(MAJOR(major));
410 if (!tap_major) {
411 retval = -EINVAL;
412 goto unlock;
413 }
414
415 spin_lock(&tap_major->minor_lock);
416 retval = idr_alloc(&tap_major->minor_idr, tap, 1, TAP_NUM_DEVS, GFP_ATOMIC);
417 if (retval >= 0) {
418 tap->minor = retval;
419 } else if (retval == -ENOSPC) {
420 netdev_err(tap->dev, "Too many tap devices\n");
421 retval = -EINVAL;
422 }
423 spin_unlock(&tap_major->minor_lock);
424
425unlock:
426 rcu_read_unlock();
427 return retval < 0 ? retval : 0;
428}
429EXPORT_SYMBOL_GPL(tap_get_minor);
430
431void tap_free_minor(dev_t major, struct tap_dev *tap)
432{
433 struct major_info *tap_major;
434
435 rcu_read_lock();
436 tap_major = tap_get_major(MAJOR(major));
437 if (!tap_major) {
438 goto unlock;
439 }
440
441 spin_lock(&tap_major->minor_lock);
442 if (tap->minor) {
443 idr_remove(&tap_major->minor_idr, tap->minor);
444 tap->minor = 0;
445 }
446 spin_unlock(&tap_major->minor_lock);
447
448unlock:
449 rcu_read_unlock();
450}
451EXPORT_SYMBOL_GPL(tap_free_minor);
452
453static struct tap_dev *dev_get_by_tap_file(int major, int minor)
454{
455 struct net_device *dev = NULL;
456 struct tap_dev *tap;
457 struct major_info *tap_major;
458
459 rcu_read_lock();
460 tap_major = tap_get_major(major);
461 if (!tap_major) {
462 tap = NULL;
463 goto unlock;
464 }
465
466 spin_lock(&tap_major->minor_lock);
467 tap = idr_find(&tap_major->minor_idr, minor);
468 if (tap) {
469 dev = tap->dev;
470 dev_hold(dev);
471 }
472 spin_unlock(&tap_major->minor_lock);
473
474unlock:
475 rcu_read_unlock();
476 return tap;
477}
478
479static void tap_sock_write_space(struct sock *sk)
480{
481 wait_queue_head_t *wqueue;
482
483 if (!sock_writeable(sk) ||
484 !test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags))
485 return;
486
487 wqueue = sk_sleep(sk);
488 if (wqueue && waitqueue_active(wqueue))
489 wake_up_interruptible_poll(wqueue, EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND);
490}
491
492static void tap_sock_destruct(struct sock *sk)
493{
494 struct tap_queue *q = container_of(sk, struct tap_queue, sk);
495
496 ptr_ring_cleanup(&q->ring, __skb_array_destroy_skb);
497}
498
499static int tap_open(struct inode *inode, struct file *file)
500{
501 struct net *net = current->nsproxy->net_ns;
502 struct tap_dev *tap;
503 struct tap_queue *q;
504 int err = -ENODEV;
505
506 rtnl_lock();
507 tap = dev_get_by_tap_file(imajor(inode), iminor(inode));
508 if (!tap)
509 goto err;
510
511 err = -ENOMEM;
512 q = (struct tap_queue *)sk_alloc(net, AF_UNSPEC, GFP_KERNEL,
513 &tap_proto, 0);
514 if (!q)
515 goto err;
516 if (ptr_ring_init(&q->ring, tap->dev->tx_queue_len, GFP_KERNEL)) {
517 sk_free(&q->sk);
518 goto err;
519 }
520
521 init_waitqueue_head(&q->sock.wq.wait);
522 q->sock.type = SOCK_RAW;
523 q->sock.state = SS_CONNECTED;
524 q->sock.file = file;
525 q->sock.ops = &tap_socket_ops;
526 sock_init_data(&q->sock, &q->sk);
527 q->sk.sk_write_space = tap_sock_write_space;
528 q->sk.sk_destruct = tap_sock_destruct;
529 q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP;
530 q->vnet_hdr_sz = sizeof(struct virtio_net_hdr);
531
532 /*
533 * so far only KVM virtio_net uses tap, enable zero copy between
534 * guest kernel and host kernel when lower device supports zerocopy
535 *
536 * The macvlan supports zerocopy iff the lower device supports zero
537 * copy so we don't have to look at the lower device directly.
538 */
539 if ((tap->dev->features & NETIF_F_HIGHDMA) && (tap->dev->features & NETIF_F_SG))
540 sock_set_flag(&q->sk, SOCK_ZEROCOPY);
541
542 err = tap_set_queue(tap, file, q);
543 if (err) {
544 /* tap_sock_destruct() will take care of freeing ptr_ring */
545 goto err_put;
546 }
547
548 dev_put(tap->dev);
549
550 rtnl_unlock();
551 return err;
552
553err_put:
554 sock_put(&q->sk);
555err:
556 if (tap)
557 dev_put(tap->dev);
558
559 rtnl_unlock();
560 return err;
561}
562
563static int tap_release(struct inode *inode, struct file *file)
564{
565 struct tap_queue *q = file->private_data;
566 tap_put_queue(q);
567 return 0;
568}
569
570static __poll_t tap_poll(struct file *file, poll_table *wait)
571{
572 struct tap_queue *q = file->private_data;
573 __poll_t mask = EPOLLERR;
574
575 if (!q)
576 goto out;
577
578 mask = 0;
579 poll_wait(file, &q->sock.wq.wait, wait);
580
581 if (!ptr_ring_empty(&q->ring))
582 mask |= EPOLLIN | EPOLLRDNORM;
583
584 if (sock_writeable(&q->sk) ||
585 (!test_and_set_bit(SOCKWQ_ASYNC_NOSPACE, &q->sock.flags) &&
586 sock_writeable(&q->sk)))
587 mask |= EPOLLOUT | EPOLLWRNORM;
588
589out:
590 return mask;
591}
592
593static inline struct sk_buff *tap_alloc_skb(struct sock *sk, size_t prepad,
594 size_t len, size_t linear,
595 int noblock, int *err)
596{
597 struct sk_buff *skb;
598
599 /* Under a page? Don't bother with paged skb. */
600 if (prepad + len < PAGE_SIZE || !linear)
601 linear = len;
602
603 skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
604 err, 0);
605 if (!skb)
606 return NULL;
607
608 skb_reserve(skb, prepad);
609 skb_put(skb, linear);
610 skb->data_len = len - linear;
611 skb->len += len - linear;
612
613 return skb;
614}
615
616/* Neighbour code has some assumptions on HH_DATA_MOD alignment */
617#define TAP_RESERVE HH_DATA_OFF(ETH_HLEN)
618
619/* Get packet from user space buffer */
620static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,
621 struct iov_iter *from, int noblock)
622{
623 int good_linear = SKB_MAX_HEAD(TAP_RESERVE);
624 struct sk_buff *skb;
625 struct tap_dev *tap;
626 unsigned long total_len = iov_iter_count(from);
627 unsigned long len = total_len;
628 int err;
629 struct virtio_net_hdr vnet_hdr = { 0 };
630 int vnet_hdr_len = 0;
631 int copylen = 0;
632 int depth;
633 bool zerocopy = false;
634 size_t linear;
635
636 if (q->flags & IFF_VNET_HDR) {
637 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
638
639 err = -EINVAL;
640 if (len < vnet_hdr_len)
641 goto err;
642 len -= vnet_hdr_len;
643
644 err = -EFAULT;
645 if (!copy_from_iter_full(&vnet_hdr, sizeof(vnet_hdr), from))
646 goto err;
647 iov_iter_advance(from, vnet_hdr_len - sizeof(vnet_hdr));
648 if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
649 tap16_to_cpu(q, vnet_hdr.csum_start) +
650 tap16_to_cpu(q, vnet_hdr.csum_offset) + 2 >
651 tap16_to_cpu(q, vnet_hdr.hdr_len))
652 vnet_hdr.hdr_len = cpu_to_tap16(q,
653 tap16_to_cpu(q, vnet_hdr.csum_start) +
654 tap16_to_cpu(q, vnet_hdr.csum_offset) + 2);
655 err = -EINVAL;
656 if (tap16_to_cpu(q, vnet_hdr.hdr_len) > len)
657 goto err;
658 }
659
660 err = -EINVAL;
661 if (unlikely(len < ETH_HLEN))
662 goto err;
663
664 if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) {
665 struct iov_iter i;
666
667 copylen = vnet_hdr.hdr_len ?
668 tap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN;
669 if (copylen > good_linear)
670 copylen = good_linear;
671 else if (copylen < ETH_HLEN)
672 copylen = ETH_HLEN;
673 linear = copylen;
674 i = *from;
675 iov_iter_advance(&i, copylen);
676 if (iov_iter_npages(&i, INT_MAX) <= MAX_SKB_FRAGS)
677 zerocopy = true;
678 }
679
680 if (!zerocopy) {
681 copylen = len;
682 linear = tap16_to_cpu(q, vnet_hdr.hdr_len);
683 if (linear > good_linear)
684 linear = good_linear;
685 else if (linear < ETH_HLEN)
686 linear = ETH_HLEN;
687 }
688
689 skb = tap_alloc_skb(&q->sk, TAP_RESERVE, copylen,
690 linear, noblock, &err);
691 if (!skb)
692 goto err;
693
694 if (zerocopy)
695 err = zerocopy_sg_from_iter(skb, from);
696 else
697 err = skb_copy_datagram_from_iter(skb, 0, from, len);
698
699 if (err)
700 goto err_kfree;
701
702 skb_set_network_header(skb, ETH_HLEN);
703 skb_reset_mac_header(skb);
704 skb->protocol = eth_hdr(skb)->h_proto;
705
706 if (vnet_hdr_len) {
707 err = virtio_net_hdr_to_skb(skb, &vnet_hdr,
708 tap_is_little_endian(q));
709 if (err)
710 goto err_kfree;
711 }
712
713 skb_probe_transport_header(skb);
714
715 /* Move network header to the right position for VLAN tagged packets */
716 if ((skb->protocol == htons(ETH_P_8021Q) ||
717 skb->protocol == htons(ETH_P_8021AD)) &&
718 __vlan_get_protocol(skb, skb->protocol, &depth) != 0)
719 skb_set_network_header(skb, depth);
720
721 rcu_read_lock();
722 tap = rcu_dereference(q->tap);
723 /* copy skb_ubuf_info for callback when skb has no error */
724 if (zerocopy) {
725 skb_shinfo(skb)->destructor_arg = msg_control;
726 skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
727 skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
728 } else if (msg_control) {
729 struct ubuf_info *uarg = msg_control;
730 uarg->callback(uarg, false);
731 }
732
733 if (tap) {
734 skb->dev = tap->dev;
735 dev_queue_xmit(skb);
736 } else {
737 kfree_skb(skb);
738 }
739 rcu_read_unlock();
740
741 return total_len;
742
743err_kfree:
744 kfree_skb(skb);
745
746err:
747 rcu_read_lock();
748 tap = rcu_dereference(q->tap);
749 if (tap && tap->count_tx_dropped)
750 tap->count_tx_dropped(tap);
751 rcu_read_unlock();
752
753 return err;
754}
755
756static ssize_t tap_write_iter(struct kiocb *iocb, struct iov_iter *from)
757{
758 struct file *file = iocb->ki_filp;
759 struct tap_queue *q = file->private_data;
760
761 return tap_get_user(q, NULL, from, file->f_flags & O_NONBLOCK);
762}
763
764/* Put packet to the user space buffer */
765static ssize_t tap_put_user(struct tap_queue *q,
766 const struct sk_buff *skb,
767 struct iov_iter *iter)
768{
769 int ret;
770 int vnet_hdr_len = 0;
771 int vlan_offset = 0;
772 int total;
773
774 if (q->flags & IFF_VNET_HDR) {
775 int vlan_hlen = skb_vlan_tag_present(skb) ? VLAN_HLEN : 0;
776 struct virtio_net_hdr vnet_hdr;
777
778 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
779 if (iov_iter_count(iter) < vnet_hdr_len)
780 return -EINVAL;
781
782 if (virtio_net_hdr_from_skb(skb, &vnet_hdr,
783 tap_is_little_endian(q), true,
784 vlan_hlen))
785 BUG();
786
787 if (copy_to_iter(&vnet_hdr, sizeof(vnet_hdr), iter) !=
788 sizeof(vnet_hdr))
789 return -EFAULT;
790
791 iov_iter_advance(iter, vnet_hdr_len - sizeof(vnet_hdr));
792 }
793 total = vnet_hdr_len;
794 total += skb->len;
795
796 if (skb_vlan_tag_present(skb)) {
797 struct {
798 __be16 h_vlan_proto;
799 __be16 h_vlan_TCI;
800 } veth;
801 veth.h_vlan_proto = skb->vlan_proto;
802 veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
803
804 vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
805 total += VLAN_HLEN;
806
807 ret = skb_copy_datagram_iter(skb, 0, iter, vlan_offset);
808 if (ret || !iov_iter_count(iter))
809 goto done;
810
811 ret = copy_to_iter(&veth, sizeof(veth), iter);
812 if (ret != sizeof(veth) || !iov_iter_count(iter))
813 goto done;
814 }
815
816 ret = skb_copy_datagram_iter(skb, vlan_offset, iter,
817 skb->len - vlan_offset);
818
819done:
820 return ret ? ret : total;
821}
822
823static ssize_t tap_do_read(struct tap_queue *q,
824 struct iov_iter *to,
825 int noblock, struct sk_buff *skb)
826{
827 DEFINE_WAIT(wait);
828 ssize_t ret = 0;
829
830 if (!iov_iter_count(to)) {
831 kfree_skb(skb);
832 return 0;
833 }
834
835 if (skb)
836 goto put;
837
838 while (1) {
839 if (!noblock)
840 prepare_to_wait(sk_sleep(&q->sk), &wait,
841 TASK_INTERRUPTIBLE);
842
843 /* Read frames from the queue */
844 skb = ptr_ring_consume(&q->ring);
845 if (skb)
846 break;
847 if (noblock) {
848 ret = -EAGAIN;
849 break;
850 }
851 if (signal_pending(current)) {
852 ret = -ERESTARTSYS;
853 break;
854 }
855 /* Nothing to read, let's sleep */
856 schedule();
857 }
858 if (!noblock)
859 finish_wait(sk_sleep(&q->sk), &wait);
860
861put:
862 if (skb) {
863 ret = tap_put_user(q, skb, to);
864 if (unlikely(ret < 0))
865 kfree_skb(skb);
866 else
867 consume_skb(skb);
868 }
869 return ret;
870}
871
872static ssize_t tap_read_iter(struct kiocb *iocb, struct iov_iter *to)
873{
874 struct file *file = iocb->ki_filp;
875 struct tap_queue *q = file->private_data;
876 ssize_t len = iov_iter_count(to), ret;
877
878 ret = tap_do_read(q, to, file->f_flags & O_NONBLOCK, NULL);
879 ret = min_t(ssize_t, ret, len);
880 if (ret > 0)
881 iocb->ki_pos = ret;
882 return ret;
883}
884
885static struct tap_dev *tap_get_tap_dev(struct tap_queue *q)
886{
887 struct tap_dev *tap;
888
889 ASSERT_RTNL();
890 tap = rtnl_dereference(q->tap);
891 if (tap)
892 dev_hold(tap->dev);
893
894 return tap;
895}
896
897static void tap_put_tap_dev(struct tap_dev *tap)
898{
899 dev_put(tap->dev);
900}
901
902static int tap_ioctl_set_queue(struct file *file, unsigned int flags)
903{
904 struct tap_queue *q = file->private_data;
905 struct tap_dev *tap;
906 int ret;
907
908 tap = tap_get_tap_dev(q);
909 if (!tap)
910 return -EINVAL;
911
912 if (flags & IFF_ATTACH_QUEUE)
913 ret = tap_enable_queue(tap, file, q);
914 else if (flags & IFF_DETACH_QUEUE)
915 ret = tap_disable_queue(q);
916 else
917 ret = -EINVAL;
918
919 tap_put_tap_dev(tap);
920 return ret;
921}
922
923static int set_offload(struct tap_queue *q, unsigned long arg)
924{
925 struct tap_dev *tap;
926 netdev_features_t features;
927 netdev_features_t feature_mask = 0;
928
929 tap = rtnl_dereference(q->tap);
930 if (!tap)
931 return -ENOLINK;
932
933 features = tap->dev->features;
934
935 if (arg & TUN_F_CSUM) {
936 feature_mask = NETIF_F_HW_CSUM;
937
938 if (arg & (TUN_F_TSO4 | TUN_F_TSO6)) {
939 if (arg & TUN_F_TSO_ECN)
940 feature_mask |= NETIF_F_TSO_ECN;
941 if (arg & TUN_F_TSO4)
942 feature_mask |= NETIF_F_TSO;
943 if (arg & TUN_F_TSO6)
944 feature_mask |= NETIF_F_TSO6;
945 }
946 }
947
948 /* tun/tap driver inverts the usage for TSO offloads, where
949 * setting the TSO bit means that the userspace wants to
950 * accept TSO frames and turning it off means that user space
951 * does not support TSO.
952 * For tap, we have to invert it to mean the same thing.
953 * When user space turns off TSO, we turn off GSO/LRO so that
954 * user-space will not receive TSO frames.
955 */
956 if (feature_mask & (NETIF_F_TSO | NETIF_F_TSO6))
957 features |= RX_OFFLOADS;
958 else
959 features &= ~RX_OFFLOADS;
960
961 /* tap_features are the same as features on tun/tap and
962 * reflect user expectations.
963 */
964 tap->tap_features = feature_mask;
965 if (tap->update_features)
966 tap->update_features(tap, features);
967
968 return 0;
969}
970
971/*
972 * provide compatibility with generic tun/tap interface
973 */
974static long tap_ioctl(struct file *file, unsigned int cmd,
975 unsigned long arg)
976{
977 struct tap_queue *q = file->private_data;
978 struct tap_dev *tap;
979 void __user *argp = (void __user *)arg;
980 struct ifreq __user *ifr = argp;
981 unsigned int __user *up = argp;
982 unsigned short u;
983 int __user *sp = argp;
984 struct sockaddr sa;
985 int s;
986 int ret;
987
988 switch (cmd) {
989 case TUNSETIFF:
990 /* ignore the name, just look at flags */
991 if (get_user(u, &ifr->ifr_flags))
992 return -EFAULT;
993
994 ret = 0;
995 if ((u & ~TAP_IFFEATURES) != (IFF_NO_PI | IFF_TAP))
996 ret = -EINVAL;
997 else
998 q->flags = (q->flags & ~TAP_IFFEATURES) | u;
999
1000 return ret;
1001
1002 case TUNGETIFF:
1003 rtnl_lock();
1004 tap = tap_get_tap_dev(q);
1005 if (!tap) {
1006 rtnl_unlock();
1007 return -ENOLINK;
1008 }
1009
1010 ret = 0;
1011 u = q->flags;
1012 if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) ||
1013 put_user(u, &ifr->ifr_flags))
1014 ret = -EFAULT;
1015 tap_put_tap_dev(tap);
1016 rtnl_unlock();
1017 return ret;
1018
1019 case TUNSETQUEUE:
1020 if (get_user(u, &ifr->ifr_flags))
1021 return -EFAULT;
1022 rtnl_lock();
1023 ret = tap_ioctl_set_queue(file, u);
1024 rtnl_unlock();
1025 return ret;
1026
1027 case TUNGETFEATURES:
1028 if (put_user(IFF_TAP | IFF_NO_PI | TAP_IFFEATURES, up))
1029 return -EFAULT;
1030 return 0;
1031
1032 case TUNSETSNDBUF:
1033 if (get_user(s, sp))
1034 return -EFAULT;
1035 if (s <= 0)
1036 return -EINVAL;
1037
1038 q->sk.sk_sndbuf = s;
1039 return 0;
1040
1041 case TUNGETVNETHDRSZ:
1042 s = q->vnet_hdr_sz;
1043 if (put_user(s, sp))
1044 return -EFAULT;
1045 return 0;
1046
1047 case TUNSETVNETHDRSZ:
1048 if (get_user(s, sp))
1049 return -EFAULT;
1050 if (s < (int)sizeof(struct virtio_net_hdr))
1051 return -EINVAL;
1052
1053 q->vnet_hdr_sz = s;
1054 return 0;
1055
1056 case TUNGETVNETLE:
1057 s = !!(q->flags & TAP_VNET_LE);
1058 if (put_user(s, sp))
1059 return -EFAULT;
1060 return 0;
1061
1062 case TUNSETVNETLE:
1063 if (get_user(s, sp))
1064 return -EFAULT;
1065 if (s)
1066 q->flags |= TAP_VNET_LE;
1067 else
1068 q->flags &= ~TAP_VNET_LE;
1069 return 0;
1070
1071 case TUNGETVNETBE:
1072 return tap_get_vnet_be(q, sp);
1073
1074 case TUNSETVNETBE:
1075 return tap_set_vnet_be(q, sp);
1076
1077 case TUNSETOFFLOAD:
1078 /* let the user check for future flags */
1079 if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
1080 TUN_F_TSO_ECN | TUN_F_UFO))
1081 return -EINVAL;
1082
1083 rtnl_lock();
1084 ret = set_offload(q, arg);
1085 rtnl_unlock();
1086 return ret;
1087
1088 case SIOCGIFHWADDR:
1089 rtnl_lock();
1090 tap = tap_get_tap_dev(q);
1091 if (!tap) {
1092 rtnl_unlock();
1093 return -ENOLINK;
1094 }
1095 ret = 0;
1096 u = tap->dev->type;
1097 if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) ||
1098 copy_to_user(&ifr->ifr_hwaddr.sa_data, tap->dev->dev_addr, ETH_ALEN) ||
1099 put_user(u, &ifr->ifr_hwaddr.sa_family))
1100 ret = -EFAULT;
1101 tap_put_tap_dev(tap);
1102 rtnl_unlock();
1103 return ret;
1104
1105 case SIOCSIFHWADDR:
1106 if (copy_from_user(&sa, &ifr->ifr_hwaddr, sizeof(sa)))
1107 return -EFAULT;
1108 rtnl_lock();
1109 tap = tap_get_tap_dev(q);
1110 if (!tap) {
1111 rtnl_unlock();
1112 return -ENOLINK;
1113 }
1114 ret = dev_set_mac_address(tap->dev, &sa, NULL);
1115 tap_put_tap_dev(tap);
1116 rtnl_unlock();
1117 return ret;
1118
1119 default:
1120 return -EINVAL;
1121 }
1122}
1123
1124static const struct file_operations tap_fops = {
1125 .owner = THIS_MODULE,
1126 .open = tap_open,
1127 .release = tap_release,
1128 .read_iter = tap_read_iter,
1129 .write_iter = tap_write_iter,
1130 .poll = tap_poll,
1131 .llseek = no_llseek,
1132 .unlocked_ioctl = tap_ioctl,
1133 .compat_ioctl = compat_ptr_ioctl,
1134};
1135
1136static int tap_get_user_xdp(struct tap_queue *q, struct xdp_buff *xdp)
1137{
1138 struct tun_xdp_hdr *hdr = xdp->data_hard_start;
1139 struct virtio_net_hdr *gso = &hdr->gso;
1140 int buflen = hdr->buflen;
1141 int vnet_hdr_len = 0;
1142 struct tap_dev *tap;
1143 struct sk_buff *skb;
1144 int err, depth;
1145
1146 if (q->flags & IFF_VNET_HDR)
1147 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
1148
1149 skb = build_skb(xdp->data_hard_start, buflen);
1150 if (!skb) {
1151 err = -ENOMEM;
1152 goto err;
1153 }
1154
1155 skb_reserve(skb, xdp->data - xdp->data_hard_start);
1156 skb_put(skb, xdp->data_end - xdp->data);
1157
1158 skb_set_network_header(skb, ETH_HLEN);
1159 skb_reset_mac_header(skb);
1160 skb->protocol = eth_hdr(skb)->h_proto;
1161
1162 if (vnet_hdr_len) {
1163 err = virtio_net_hdr_to_skb(skb, gso, tap_is_little_endian(q));
1164 if (err)
1165 goto err_kfree;
1166 }
1167
1168 /* Move network header to the right position for VLAN tagged packets */
1169 if ((skb->protocol == htons(ETH_P_8021Q) ||
1170 skb->protocol == htons(ETH_P_8021AD)) &&
1171 __vlan_get_protocol(skb, skb->protocol, &depth) != 0)
1172 skb_set_network_header(skb, depth);
1173
1174 rcu_read_lock();
1175 tap = rcu_dereference(q->tap);
1176 if (tap) {
1177 skb->dev = tap->dev;
1178 skb_probe_transport_header(skb);
1179 dev_queue_xmit(skb);
1180 } else {
1181 kfree_skb(skb);
1182 }
1183 rcu_read_unlock();
1184
1185 return 0;
1186
1187err_kfree:
1188 kfree_skb(skb);
1189err:
1190 rcu_read_lock();
1191 tap = rcu_dereference(q->tap);
1192 if (tap && tap->count_tx_dropped)
1193 tap->count_tx_dropped(tap);
1194 rcu_read_unlock();
1195 return err;
1196}
1197
1198static int tap_sendmsg(struct socket *sock, struct msghdr *m,
1199 size_t total_len)
1200{
1201 struct tap_queue *q = container_of(sock, struct tap_queue, sock);
1202 struct tun_msg_ctl *ctl = m->msg_control;
1203 struct xdp_buff *xdp;
1204 int i;
1205
1206 if (ctl && (ctl->type == TUN_MSG_PTR)) {
1207 for (i = 0; i < ctl->num; i++) {
1208 xdp = &((struct xdp_buff *)ctl->ptr)[i];
1209 tap_get_user_xdp(q, xdp);
1210 }
1211 return 0;
1212 }
1213
1214 return tap_get_user(q, ctl ? ctl->ptr : NULL, &m->msg_iter,
1215 m->msg_flags & MSG_DONTWAIT);
1216}
1217
1218static int tap_recvmsg(struct socket *sock, struct msghdr *m,
1219 size_t total_len, int flags)
1220{
1221 struct tap_queue *q = container_of(sock, struct tap_queue, sock);
1222 struct sk_buff *skb = m->msg_control;
1223 int ret;
1224 if (flags & ~(MSG_DONTWAIT|MSG_TRUNC)) {
1225 kfree_skb(skb);
1226 return -EINVAL;
1227 }
1228 ret = tap_do_read(q, &m->msg_iter, flags & MSG_DONTWAIT, skb);
1229 if (ret > total_len) {
1230 m->msg_flags |= MSG_TRUNC;
1231 ret = flags & MSG_TRUNC ? ret : total_len;
1232 }
1233 return ret;
1234}
1235
1236static int tap_peek_len(struct socket *sock)
1237{
1238 struct tap_queue *q = container_of(sock, struct tap_queue,
1239 sock);
1240 return PTR_RING_PEEK_CALL(&q->ring, __skb_array_len_with_tag);
1241}
1242
1243/* Ops structure to mimic raw sockets with tun */
1244static const struct proto_ops tap_socket_ops = {
1245 .sendmsg = tap_sendmsg,
1246 .recvmsg = tap_recvmsg,
1247 .peek_len = tap_peek_len,
1248};
1249
1250/* Get an underlying socket object from tun file. Returns error unless file is
1251 * attached to a device. The returned object works like a packet socket, it
1252 * can be used for sock_sendmsg/sock_recvmsg. The caller is responsible for
1253 * holding a reference to the file for as long as the socket is in use. */
1254struct socket *tap_get_socket(struct file *file)
1255{
1256 struct tap_queue *q;
1257 if (file->f_op != &tap_fops)
1258 return ERR_PTR(-EINVAL);
1259 q = file->private_data;
1260 if (!q)
1261 return ERR_PTR(-EBADFD);
1262 return &q->sock;
1263}
1264EXPORT_SYMBOL_GPL(tap_get_socket);
1265
1266struct ptr_ring *tap_get_ptr_ring(struct file *file)
1267{
1268 struct tap_queue *q;
1269
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->ring;
1276}
1277EXPORT_SYMBOL_GPL(tap_get_ptr_ring);
1278
1279int tap_queue_resize(struct tap_dev *tap)
1280{
1281 struct net_device *dev = tap->dev;
1282 struct tap_queue *q;
1283 struct ptr_ring **rings;
1284 int n = tap->numqueues;
1285 int ret, i = 0;
1286
1287 rings = kmalloc_array(n, sizeof(*rings), GFP_KERNEL);
1288 if (!rings)
1289 return -ENOMEM;
1290
1291 list_for_each_entry(q, &tap->queue_list, next)
1292 rings[i++] = &q->ring;
1293
1294 ret = ptr_ring_resize_multiple(rings, n,
1295 dev->tx_queue_len, GFP_KERNEL,
1296 __skb_array_destroy_skb);
1297
1298 kfree(rings);
1299 return ret;
1300}
1301EXPORT_SYMBOL_GPL(tap_queue_resize);
1302
1303static int tap_list_add(dev_t major, const char *device_name)
1304{
1305 struct major_info *tap_major;
1306
1307 tap_major = kzalloc(sizeof(*tap_major), GFP_ATOMIC);
1308 if (!tap_major)
1309 return -ENOMEM;
1310
1311 tap_major->major = MAJOR(major);
1312
1313 idr_init(&tap_major->minor_idr);
1314 spin_lock_init(&tap_major->minor_lock);
1315
1316 tap_major->device_name = device_name;
1317
1318 list_add_tail_rcu(&tap_major->next, &major_list);
1319 return 0;
1320}
1321
1322int tap_create_cdev(struct cdev *tap_cdev, dev_t *tap_major,
1323 const char *device_name, struct module *module)
1324{
1325 int err;
1326
1327 err = alloc_chrdev_region(tap_major, 0, TAP_NUM_DEVS, device_name);
1328 if (err)
1329 goto out1;
1330
1331 cdev_init(tap_cdev, &tap_fops);
1332 tap_cdev->owner = module;
1333 err = cdev_add(tap_cdev, *tap_major, TAP_NUM_DEVS);
1334 if (err)
1335 goto out2;
1336
1337 err = tap_list_add(*tap_major, device_name);
1338 if (err)
1339 goto out3;
1340
1341 return 0;
1342
1343out3:
1344 cdev_del(tap_cdev);
1345out2:
1346 unregister_chrdev_region(*tap_major, TAP_NUM_DEVS);
1347out1:
1348 return err;
1349}
1350EXPORT_SYMBOL_GPL(tap_create_cdev);
1351
1352void tap_destroy_cdev(dev_t major, struct cdev *tap_cdev)
1353{
1354 struct major_info *tap_major, *tmp;
1355
1356 cdev_del(tap_cdev);
1357 unregister_chrdev_region(major, TAP_NUM_DEVS);
1358 list_for_each_entry_safe(tap_major, tmp, &major_list, next) {
1359 if (tap_major->major == MAJOR(major)) {
1360 idr_destroy(&tap_major->minor_idr);
1361 list_del_rcu(&tap_major->next);
1362 kfree_rcu(tap_major, rcu);
1363 }
1364 }
1365}
1366EXPORT_SYMBOL_GPL(tap_destroy_cdev);
1367
1368MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>");
1369MODULE_AUTHOR("Sainath Grandhi <sainath.grandhi@intel.com>");
1370MODULE_LICENSE("GPL");