1 #include <linux/etherdevice.h> 2 #include <linux/if_tap.h> 3 #include <linux/if_vlan.h> 4 #include <linux/interrupt.h> 5 #include <linux/nsproxy.h> 6 #include <linux/compat.h> 7 #include <linux/if_tun.h> 8 #include <linux/module.h> 9 #include <linux/skbuff.h> 10 #include <linux/cache.h> 11 #include <linux/sched/signal.h> 12 #include <linux/types.h> 13 #include <linux/slab.h> 14 #include <linux/wait.h> 15 #include <linux/cdev.h> 16 #include <linux/idr.h> 17 #include <linux/fs.h> 18 #include <linux/uio.h> 19 20 #include <net/net_namespace.h> 21 #include <net/rtnetlink.h> 22 #include <net/sock.h> 23 #include <linux/virtio_net.h> 24 #include <linux/skb_array.h> 25 26 #define TAP_IFFEATURES (IFF_VNET_HDR | IFF_MULTI_QUEUE) 27 28 #define TAP_VNET_LE 0x80000000 29 #define TAP_VNET_BE 0x40000000 30 31 #ifdef CONFIG_TUN_VNET_CROSS_LE 32 static inline bool tap_legacy_is_little_endian(struct tap_queue *q) 33 { 34 return q->flags & TAP_VNET_BE ? false : 35 virtio_legacy_is_little_endian(); 36 } 37 38 static long tap_get_vnet_be(struct tap_queue *q, int __user *sp) 39 { 40 int s = !!(q->flags & TAP_VNET_BE); 41 42 if (put_user(s, sp)) 43 return -EFAULT; 44 45 return 0; 46 } 47 48 static long tap_set_vnet_be(struct tap_queue *q, int __user *sp) 49 { 50 int s; 51 52 if (get_user(s, sp)) 53 return -EFAULT; 54 55 if (s) 56 q->flags |= TAP_VNET_BE; 57 else 58 q->flags &= ~TAP_VNET_BE; 59 60 return 0; 61 } 62 #else 63 static inline bool tap_legacy_is_little_endian(struct tap_queue *q) 64 { 65 return virtio_legacy_is_little_endian(); 66 } 67 68 static long tap_get_vnet_be(struct tap_queue *q, int __user *argp) 69 { 70 return -EINVAL; 71 } 72 73 static long tap_set_vnet_be(struct tap_queue *q, int __user *argp) 74 { 75 return -EINVAL; 76 } 77 #endif /* CONFIG_TUN_VNET_CROSS_LE */ 78 79 static inline bool tap_is_little_endian(struct tap_queue *q) 80 { 81 return q->flags & TAP_VNET_LE || 82 tap_legacy_is_little_endian(q); 83 } 84 85 static inline u16 tap16_to_cpu(struct tap_queue *q, __virtio16 val) 86 { 87 return __virtio16_to_cpu(tap_is_little_endian(q), val); 88 } 89 90 static inline __virtio16 cpu_to_tap16(struct tap_queue *q, u16 val) 91 { 92 return __cpu_to_virtio16(tap_is_little_endian(q), val); 93 } 94 95 static struct proto tap_proto = { 96 .name = "tap", 97 .owner = THIS_MODULE, 98 .obj_size = sizeof(struct tap_queue), 99 }; 100 101 #define TAP_NUM_DEVS (1U << MINORBITS) 102 103 static LIST_HEAD(major_list); 104 105 struct major_info { 106 struct rcu_head rcu; 107 dev_t major; 108 struct idr minor_idr; 109 struct mutex minor_lock; 110 const char *device_name; 111 struct list_head next; 112 }; 113 114 #define GOODCOPY_LEN 128 115 116 static const struct proto_ops tap_socket_ops; 117 118 #define RX_OFFLOADS (NETIF_F_GRO | NETIF_F_LRO) 119 #define TAP_FEATURES (NETIF_F_GSO | NETIF_F_SG | NETIF_F_FRAGLIST) 120 121 static struct tap_dev *tap_dev_get_rcu(const struct net_device *dev) 122 { 123 return rcu_dereference(dev->rx_handler_data); 124 } 125 126 /* 127 * RCU usage: 128 * The tap_queue and the macvlan_dev are loosely coupled, the 129 * pointers from one to the other can only be read while rcu_read_lock 130 * or rtnl is held. 131 * 132 * Both the file and the macvlan_dev hold a reference on the tap_queue 133 * through sock_hold(&q->sk). When the macvlan_dev goes away first, 134 * q->vlan becomes inaccessible. When the files gets closed, 135 * tap_get_queue() fails. 136 * 137 * There may still be references to the struct sock inside of the 138 * queue from outbound SKBs, but these never reference back to the 139 * file or the dev. The data structure is freed through __sk_free 140 * when both our references and any pending SKBs are gone. 141 */ 142 143 static int tap_enable_queue(struct tap_dev *tap, struct file *file, 144 struct tap_queue *q) 145 { 146 int err = -EINVAL; 147 148 ASSERT_RTNL(); 149 150 if (q->enabled) 151 goto out; 152 153 err = 0; 154 rcu_assign_pointer(tap->taps[tap->numvtaps], q); 155 q->queue_index = tap->numvtaps; 156 q->enabled = true; 157 158 tap->numvtaps++; 159 out: 160 return err; 161 } 162 163 /* Requires RTNL */ 164 static int tap_set_queue(struct tap_dev *tap, struct file *file, 165 struct tap_queue *q) 166 { 167 if (tap->numqueues == MAX_TAP_QUEUES) 168 return -EBUSY; 169 170 rcu_assign_pointer(q->tap, tap); 171 rcu_assign_pointer(tap->taps[tap->numvtaps], q); 172 sock_hold(&q->sk); 173 174 q->file = file; 175 q->queue_index = tap->numvtaps; 176 q->enabled = true; 177 file->private_data = q; 178 list_add_tail(&q->next, &tap->queue_list); 179 180 tap->numvtaps++; 181 tap->numqueues++; 182 183 return 0; 184 } 185 186 static int tap_disable_queue(struct tap_queue *q) 187 { 188 struct tap_dev *tap; 189 struct tap_queue *nq; 190 191 ASSERT_RTNL(); 192 if (!q->enabled) 193 return -EINVAL; 194 195 tap = rtnl_dereference(q->tap); 196 197 if (tap) { 198 int index = q->queue_index; 199 BUG_ON(index >= tap->numvtaps); 200 nq = rtnl_dereference(tap->taps[tap->numvtaps - 1]); 201 nq->queue_index = index; 202 203 rcu_assign_pointer(tap->taps[index], nq); 204 RCU_INIT_POINTER(tap->taps[tap->numvtaps - 1], NULL); 205 q->enabled = false; 206 207 tap->numvtaps--; 208 } 209 210 return 0; 211 } 212 213 /* 214 * The file owning the queue got closed, give up both 215 * the reference that the files holds as well as the 216 * one from the macvlan_dev if that still exists. 217 * 218 * Using the spinlock makes sure that we don't get 219 * to the queue again after destroying it. 220 */ 221 static void tap_put_queue(struct tap_queue *q) 222 { 223 struct tap_dev *tap; 224 225 rtnl_lock(); 226 tap = rtnl_dereference(q->tap); 227 228 if (tap) { 229 if (q->enabled) 230 BUG_ON(tap_disable_queue(q)); 231 232 tap->numqueues--; 233 RCU_INIT_POINTER(q->tap, NULL); 234 sock_put(&q->sk); 235 list_del_init(&q->next); 236 } 237 238 rtnl_unlock(); 239 240 synchronize_rcu(); 241 sock_put(&q->sk); 242 } 243 244 /* 245 * Select a queue based on the rxq of the device on which this packet 246 * arrived. If the incoming device is not mq, calculate a flow hash 247 * to select a queue. If all fails, find the first available queue. 248 * Cache vlan->numvtaps since it can become zero during the execution 249 * of this function. 250 */ 251 static struct tap_queue *tap_get_queue(struct tap_dev *tap, 252 struct sk_buff *skb) 253 { 254 struct tap_queue *queue = NULL; 255 /* Access to taps array is protected by rcu, but access to numvtaps 256 * isn't. Below we use it to lookup a queue, but treat it as a hint 257 * and validate that the result isn't NULL - in case we are 258 * racing against queue removal. 259 */ 260 int numvtaps = ACCESS_ONCE(tap->numvtaps); 261 __u32 rxq; 262 263 if (!numvtaps) 264 goto out; 265 266 if (numvtaps == 1) 267 goto single; 268 269 /* Check if we can use flow to select a queue */ 270 rxq = skb_get_hash(skb); 271 if (rxq) { 272 queue = rcu_dereference(tap->taps[rxq % numvtaps]); 273 goto out; 274 } 275 276 if (likely(skb_rx_queue_recorded(skb))) { 277 rxq = skb_get_rx_queue(skb); 278 279 while (unlikely(rxq >= numvtaps)) 280 rxq -= numvtaps; 281 282 queue = rcu_dereference(tap->taps[rxq]); 283 goto out; 284 } 285 286 single: 287 queue = rcu_dereference(tap->taps[0]); 288 out: 289 return queue; 290 } 291 292 /* 293 * The net_device is going away, give up the reference 294 * that it holds on all queues and safely set the pointer 295 * from the queues to NULL. 296 */ 297 void tap_del_queues(struct tap_dev *tap) 298 { 299 struct tap_queue *q, *tmp; 300 301 ASSERT_RTNL(); 302 list_for_each_entry_safe(q, tmp, &tap->queue_list, next) { 303 list_del_init(&q->next); 304 RCU_INIT_POINTER(q->tap, NULL); 305 if (q->enabled) 306 tap->numvtaps--; 307 tap->numqueues--; 308 sock_put(&q->sk); 309 } 310 BUG_ON(tap->numvtaps); 311 BUG_ON(tap->numqueues); 312 /* guarantee that any future tap_set_queue will fail */ 313 tap->numvtaps = MAX_TAP_QUEUES; 314 } 315 EXPORT_SYMBOL_GPL(tap_del_queues); 316 317 rx_handler_result_t tap_handle_frame(struct sk_buff **pskb) 318 { 319 struct sk_buff *skb = *pskb; 320 struct net_device *dev = skb->dev; 321 struct tap_dev *tap; 322 struct tap_queue *q; 323 netdev_features_t features = TAP_FEATURES; 324 325 tap = tap_dev_get_rcu(dev); 326 if (!tap) 327 return RX_HANDLER_PASS; 328 329 q = tap_get_queue(tap, skb); 330 if (!q) 331 return RX_HANDLER_PASS; 332 333 if (__skb_array_full(&q->skb_array)) 334 goto drop; 335 336 skb_push(skb, ETH_HLEN); 337 338 /* Apply the forward feature mask so that we perform segmentation 339 * according to users wishes. This only works if VNET_HDR is 340 * enabled. 341 */ 342 if (q->flags & IFF_VNET_HDR) 343 features |= tap->tap_features; 344 if (netif_needs_gso(skb, features)) { 345 struct sk_buff *segs = __skb_gso_segment(skb, features, false); 346 347 if (IS_ERR(segs)) 348 goto drop; 349 350 if (!segs) { 351 if (skb_array_produce(&q->skb_array, skb)) 352 goto drop; 353 goto wake_up; 354 } 355 356 consume_skb(skb); 357 while (segs) { 358 struct sk_buff *nskb = segs->next; 359 360 segs->next = NULL; 361 if (skb_array_produce(&q->skb_array, segs)) { 362 kfree_skb(segs); 363 kfree_skb_list(nskb); 364 break; 365 } 366 segs = nskb; 367 } 368 } else { 369 /* If we receive a partial checksum and the tap side 370 * doesn't support checksum offload, compute the checksum. 371 * Note: it doesn't matter which checksum feature to 372 * check, we either support them all or none. 373 */ 374 if (skb->ip_summed == CHECKSUM_PARTIAL && 375 !(features & NETIF_F_CSUM_MASK) && 376 skb_checksum_help(skb)) 377 goto drop; 378 if (skb_array_produce(&q->skb_array, skb)) 379 goto drop; 380 } 381 382 wake_up: 383 wake_up_interruptible_poll(sk_sleep(&q->sk), POLLIN | POLLRDNORM | POLLRDBAND); 384 return RX_HANDLER_CONSUMED; 385 386 drop: 387 /* Count errors/drops only here, thus don't care about args. */ 388 if (tap->count_rx_dropped) 389 tap->count_rx_dropped(tap); 390 kfree_skb(skb); 391 return RX_HANDLER_CONSUMED; 392 } 393 EXPORT_SYMBOL_GPL(tap_handle_frame); 394 395 static struct major_info *tap_get_major(int major) 396 { 397 struct major_info *tap_major; 398 399 list_for_each_entry_rcu(tap_major, &major_list, next) { 400 if (tap_major->major == major) 401 return tap_major; 402 } 403 404 return NULL; 405 } 406 407 int tap_get_minor(dev_t major, struct tap_dev *tap) 408 { 409 int retval = -ENOMEM; 410 struct major_info *tap_major; 411 412 rcu_read_lock(); 413 tap_major = tap_get_major(MAJOR(major)); 414 if (!tap_major) { 415 retval = -EINVAL; 416 goto unlock; 417 } 418 419 mutex_lock(&tap_major->minor_lock); 420 retval = idr_alloc(&tap_major->minor_idr, tap, 1, TAP_NUM_DEVS, GFP_KERNEL); 421 if (retval >= 0) { 422 tap->minor = retval; 423 } else if (retval == -ENOSPC) { 424 netdev_err(tap->dev, "Too many tap devices\n"); 425 retval = -EINVAL; 426 } 427 mutex_unlock(&tap_major->minor_lock); 428 429 unlock: 430 rcu_read_unlock(); 431 return retval < 0 ? retval : 0; 432 } 433 EXPORT_SYMBOL_GPL(tap_get_minor); 434 435 void tap_free_minor(dev_t major, struct tap_dev *tap) 436 { 437 struct major_info *tap_major; 438 439 rcu_read_lock(); 440 tap_major = tap_get_major(MAJOR(major)); 441 if (!tap_major) { 442 goto unlock; 443 } 444 445 mutex_lock(&tap_major->minor_lock); 446 if (tap->minor) { 447 idr_remove(&tap_major->minor_idr, tap->minor); 448 tap->minor = 0; 449 } 450 mutex_unlock(&tap_major->minor_lock); 451 452 unlock: 453 rcu_read_unlock(); 454 } 455 EXPORT_SYMBOL_GPL(tap_free_minor); 456 457 static struct tap_dev *dev_get_by_tap_file(int major, int minor) 458 { 459 struct net_device *dev = NULL; 460 struct tap_dev *tap; 461 struct major_info *tap_major; 462 463 rcu_read_lock(); 464 tap_major = tap_get_major(major); 465 if (!tap_major) { 466 tap = NULL; 467 goto unlock; 468 } 469 470 mutex_lock(&tap_major->minor_lock); 471 tap = idr_find(&tap_major->minor_idr, minor); 472 if (tap) { 473 dev = tap->dev; 474 dev_hold(dev); 475 } 476 mutex_unlock(&tap_major->minor_lock); 477 478 unlock: 479 rcu_read_unlock(); 480 return tap; 481 } 482 483 static void tap_sock_write_space(struct sock *sk) 484 { 485 wait_queue_head_t *wqueue; 486 487 if (!sock_writeable(sk) || 488 !test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags)) 489 return; 490 491 wqueue = sk_sleep(sk); 492 if (wqueue && waitqueue_active(wqueue)) 493 wake_up_interruptible_poll(wqueue, POLLOUT | POLLWRNORM | POLLWRBAND); 494 } 495 496 static void tap_sock_destruct(struct sock *sk) 497 { 498 struct tap_queue *q = container_of(sk, struct tap_queue, sk); 499 500 skb_array_cleanup(&q->skb_array); 501 } 502 503 static int tap_open(struct inode *inode, struct file *file) 504 { 505 struct net *net = current->nsproxy->net_ns; 506 struct tap_dev *tap; 507 struct tap_queue *q; 508 int err = -ENODEV; 509 510 rtnl_lock(); 511 tap = dev_get_by_tap_file(imajor(inode), iminor(inode)); 512 if (!tap) 513 goto err; 514 515 err = -ENOMEM; 516 q = (struct tap_queue *)sk_alloc(net, AF_UNSPEC, GFP_KERNEL, 517 &tap_proto, 0); 518 if (!q) 519 goto err; 520 521 RCU_INIT_POINTER(q->sock.wq, &q->wq); 522 init_waitqueue_head(&q->wq.wait); 523 q->sock.type = SOCK_RAW; 524 q->sock.state = SS_CONNECTED; 525 q->sock.file = file; 526 q->sock.ops = &tap_socket_ops; 527 sock_init_data(&q->sock, &q->sk); 528 q->sk.sk_write_space = tap_sock_write_space; 529 q->sk.sk_destruct = tap_sock_destruct; 530 q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP; 531 q->vnet_hdr_sz = sizeof(struct virtio_net_hdr); 532 533 /* 534 * so far only KVM virtio_net uses tap, enable zero copy between 535 * guest kernel and host kernel when lower device supports zerocopy 536 * 537 * The macvlan supports zerocopy iff the lower device supports zero 538 * copy so we don't have to look at the lower device directly. 539 */ 540 if ((tap->dev->features & NETIF_F_HIGHDMA) && (tap->dev->features & NETIF_F_SG)) 541 sock_set_flag(&q->sk, SOCK_ZEROCOPY); 542 543 err = -ENOMEM; 544 if (skb_array_init(&q->skb_array, tap->dev->tx_queue_len, GFP_KERNEL)) 545 goto err_array; 546 547 err = tap_set_queue(tap, file, q); 548 if (err) 549 goto err_queue; 550 551 dev_put(tap->dev); 552 553 rtnl_unlock(); 554 return err; 555 556 err_queue: 557 skb_array_cleanup(&q->skb_array); 558 err_array: 559 sock_put(&q->sk); 560 err: 561 if (tap) 562 dev_put(tap->dev); 563 564 rtnl_unlock(); 565 return err; 566 } 567 568 static int tap_release(struct inode *inode, struct file *file) 569 { 570 struct tap_queue *q = file->private_data; 571 tap_put_queue(q); 572 return 0; 573 } 574 575 static unsigned int tap_poll(struct file *file, poll_table *wait) 576 { 577 struct tap_queue *q = file->private_data; 578 unsigned int mask = POLLERR; 579 580 if (!q) 581 goto out; 582 583 mask = 0; 584 poll_wait(file, &q->wq.wait, wait); 585 586 if (!skb_array_empty(&q->skb_array)) 587 mask |= POLLIN | POLLRDNORM; 588 589 if (sock_writeable(&q->sk) || 590 (!test_and_set_bit(SOCKWQ_ASYNC_NOSPACE, &q->sock.flags) && 591 sock_writeable(&q->sk))) 592 mask |= POLLOUT | POLLWRNORM; 593 594 out: 595 return mask; 596 } 597 598 static inline struct sk_buff *tap_alloc_skb(struct sock *sk, size_t prepad, 599 size_t len, size_t linear, 600 int noblock, int *err) 601 { 602 struct sk_buff *skb; 603 604 /* Under a page? Don't bother with paged skb. */ 605 if (prepad + len < PAGE_SIZE || !linear) 606 linear = len; 607 608 skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock, 609 err, 0); 610 if (!skb) 611 return NULL; 612 613 skb_reserve(skb, prepad); 614 skb_put(skb, linear); 615 skb->data_len = len - linear; 616 skb->len += len - linear; 617 618 return skb; 619 } 620 621 /* Neighbour code has some assumptions on HH_DATA_MOD alignment */ 622 #define TAP_RESERVE HH_DATA_OFF(ETH_HLEN) 623 624 /* Get packet from user space buffer */ 625 static ssize_t tap_get_user(struct tap_queue *q, struct msghdr *m, 626 struct iov_iter *from, int noblock) 627 { 628 int good_linear = SKB_MAX_HEAD(TAP_RESERVE); 629 struct sk_buff *skb; 630 struct tap_dev *tap; 631 unsigned long total_len = iov_iter_count(from); 632 unsigned long len = total_len; 633 int err; 634 struct virtio_net_hdr vnet_hdr = { 0 }; 635 int vnet_hdr_len = 0; 636 int copylen = 0; 637 int depth; 638 bool zerocopy = false; 639 size_t linear; 640 641 if (q->flags & IFF_VNET_HDR) { 642 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz); 643 644 err = -EINVAL; 645 if (len < vnet_hdr_len) 646 goto err; 647 len -= vnet_hdr_len; 648 649 err = -EFAULT; 650 if (!copy_from_iter_full(&vnet_hdr, sizeof(vnet_hdr), from)) 651 goto err; 652 iov_iter_advance(from, vnet_hdr_len - sizeof(vnet_hdr)); 653 if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) && 654 tap16_to_cpu(q, vnet_hdr.csum_start) + 655 tap16_to_cpu(q, vnet_hdr.csum_offset) + 2 > 656 tap16_to_cpu(q, vnet_hdr.hdr_len)) 657 vnet_hdr.hdr_len = cpu_to_tap16(q, 658 tap16_to_cpu(q, vnet_hdr.csum_start) + 659 tap16_to_cpu(q, vnet_hdr.csum_offset) + 2); 660 err = -EINVAL; 661 if (tap16_to_cpu(q, vnet_hdr.hdr_len) > len) 662 goto err; 663 } 664 665 err = -EINVAL; 666 if (unlikely(len < ETH_HLEN)) 667 goto err; 668 669 if (m && m->msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) { 670 struct iov_iter i; 671 672 copylen = vnet_hdr.hdr_len ? 673 tap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN; 674 if (copylen > good_linear) 675 copylen = good_linear; 676 else if (copylen < ETH_HLEN) 677 copylen = ETH_HLEN; 678 linear = copylen; 679 i = *from; 680 iov_iter_advance(&i, copylen); 681 if (iov_iter_npages(&i, INT_MAX) <= MAX_SKB_FRAGS) 682 zerocopy = true; 683 } 684 685 if (!zerocopy) { 686 copylen = len; 687 linear = tap16_to_cpu(q, vnet_hdr.hdr_len); 688 if (linear > good_linear) 689 linear = good_linear; 690 else if (linear < ETH_HLEN) 691 linear = ETH_HLEN; 692 } 693 694 skb = tap_alloc_skb(&q->sk, TAP_RESERVE, copylen, 695 linear, noblock, &err); 696 if (!skb) 697 goto err; 698 699 if (zerocopy) 700 err = zerocopy_sg_from_iter(skb, from); 701 else 702 err = skb_copy_datagram_from_iter(skb, 0, from, len); 703 704 if (err) 705 goto err_kfree; 706 707 skb_set_network_header(skb, ETH_HLEN); 708 skb_reset_mac_header(skb); 709 skb->protocol = eth_hdr(skb)->h_proto; 710 711 if (vnet_hdr_len) { 712 err = virtio_net_hdr_to_skb(skb, &vnet_hdr, 713 tap_is_little_endian(q)); 714 if (err) 715 goto err_kfree; 716 } 717 718 skb_probe_transport_header(skb, ETH_HLEN); 719 720 /* Move network header to the right position for VLAN tagged packets */ 721 if ((skb->protocol == htons(ETH_P_8021Q) || 722 skb->protocol == htons(ETH_P_8021AD)) && 723 __vlan_get_protocol(skb, skb->protocol, &depth) != 0) 724 skb_set_network_header(skb, depth); 725 726 rcu_read_lock(); 727 tap = rcu_dereference(q->tap); 728 /* copy skb_ubuf_info for callback when skb has no error */ 729 if (zerocopy) { 730 skb_shinfo(skb)->destructor_arg = m->msg_control; 731 skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY; 732 skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG; 733 } else if (m && m->msg_control) { 734 struct ubuf_info *uarg = m->msg_control; 735 uarg->callback(uarg, false); 736 } 737 738 if (tap) { 739 skb->dev = tap->dev; 740 dev_queue_xmit(skb); 741 } else { 742 kfree_skb(skb); 743 } 744 rcu_read_unlock(); 745 746 return total_len; 747 748 err_kfree: 749 kfree_skb(skb); 750 751 err: 752 rcu_read_lock(); 753 tap = rcu_dereference(q->tap); 754 if (tap && tap->count_tx_dropped) 755 tap->count_tx_dropped(tap); 756 rcu_read_unlock(); 757 758 return err; 759 } 760 761 static ssize_t tap_write_iter(struct kiocb *iocb, struct iov_iter *from) 762 { 763 struct file *file = iocb->ki_filp; 764 struct tap_queue *q = file->private_data; 765 766 return tap_get_user(q, NULL, from, file->f_flags & O_NONBLOCK); 767 } 768 769 /* Put packet to the user space buffer */ 770 static ssize_t tap_put_user(struct tap_queue *q, 771 const struct sk_buff *skb, 772 struct iov_iter *iter) 773 { 774 int ret; 775 int vnet_hdr_len = 0; 776 int vlan_offset = 0; 777 int total; 778 779 if (q->flags & IFF_VNET_HDR) { 780 struct virtio_net_hdr vnet_hdr; 781 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz); 782 if (iov_iter_count(iter) < vnet_hdr_len) 783 return -EINVAL; 784 785 if (virtio_net_hdr_from_skb(skb, &vnet_hdr, 786 tap_is_little_endian(q), true)) 787 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); 820 821 done: 822 return ret ? ret : total; 823 } 824 825 static ssize_t tap_do_read(struct tap_queue *q, 826 struct iov_iter *to, 827 int noblock) 828 { 829 DEFINE_WAIT(wait); 830 struct sk_buff *skb; 831 ssize_t ret = 0; 832 833 if (!iov_iter_count(to)) 834 return 0; 835 836 while (1) { 837 if (!noblock) 838 prepare_to_wait(sk_sleep(&q->sk), &wait, 839 TASK_INTERRUPTIBLE); 840 841 /* Read frames from the queue */ 842 skb = skb_array_consume(&q->skb_array); 843 if (skb) 844 break; 845 if (noblock) { 846 ret = -EAGAIN; 847 break; 848 } 849 if (signal_pending(current)) { 850 ret = -ERESTARTSYS; 851 break; 852 } 853 /* Nothing to read, let's sleep */ 854 schedule(); 855 } 856 if (!noblock) 857 finish_wait(sk_sleep(&q->sk), &wait); 858 859 if (skb) { 860 ret = tap_put_user(q, skb, to); 861 if (unlikely(ret < 0)) 862 kfree_skb(skb); 863 else 864 consume_skb(skb); 865 } 866 return ret; 867 } 868 869 static ssize_t tap_read_iter(struct kiocb *iocb, struct iov_iter *to) 870 { 871 struct file *file = iocb->ki_filp; 872 struct tap_queue *q = file->private_data; 873 ssize_t len = iov_iter_count(to), ret; 874 875 ret = tap_do_read(q, to, file->f_flags & O_NONBLOCK); 876 ret = min_t(ssize_t, ret, len); 877 if (ret > 0) 878 iocb->ki_pos = ret; 879 return ret; 880 } 881 882 static struct tap_dev *tap_get_tap_dev(struct tap_queue *q) 883 { 884 struct tap_dev *tap; 885 886 ASSERT_RTNL(); 887 tap = rtnl_dereference(q->tap); 888 if (tap) 889 dev_hold(tap->dev); 890 891 return tap; 892 } 893 894 static void tap_put_tap_dev(struct tap_dev *tap) 895 { 896 dev_put(tap->dev); 897 } 898 899 static int tap_ioctl_set_queue(struct file *file, unsigned int flags) 900 { 901 struct tap_queue *q = file->private_data; 902 struct tap_dev *tap; 903 int ret; 904 905 tap = tap_get_tap_dev(q); 906 if (!tap) 907 return -EINVAL; 908 909 if (flags & IFF_ATTACH_QUEUE) 910 ret = tap_enable_queue(tap, file, q); 911 else if (flags & IFF_DETACH_QUEUE) 912 ret = tap_disable_queue(q); 913 else 914 ret = -EINVAL; 915 916 tap_put_tap_dev(tap); 917 return ret; 918 } 919 920 static int set_offload(struct tap_queue *q, unsigned long arg) 921 { 922 struct tap_dev *tap; 923 netdev_features_t features; 924 netdev_features_t feature_mask = 0; 925 926 tap = rtnl_dereference(q->tap); 927 if (!tap) 928 return -ENOLINK; 929 930 features = tap->dev->features; 931 932 if (arg & TUN_F_CSUM) { 933 feature_mask = NETIF_F_HW_CSUM; 934 935 if (arg & (TUN_F_TSO4 | TUN_F_TSO6)) { 936 if (arg & TUN_F_TSO_ECN) 937 feature_mask |= NETIF_F_TSO_ECN; 938 if (arg & TUN_F_TSO4) 939 feature_mask |= NETIF_F_TSO; 940 if (arg & TUN_F_TSO6) 941 feature_mask |= NETIF_F_TSO6; 942 } 943 944 if (arg & TUN_F_UFO) 945 feature_mask |= NETIF_F_UFO; 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 | NETIF_F_UFO)) 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 */ 974 static 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 1036 q->sk.sk_sndbuf = s; 1037 return 0; 1038 1039 case TUNGETVNETHDRSZ: 1040 s = q->vnet_hdr_sz; 1041 if (put_user(s, sp)) 1042 return -EFAULT; 1043 return 0; 1044 1045 case TUNSETVNETHDRSZ: 1046 if (get_user(s, sp)) 1047 return -EFAULT; 1048 if (s < (int)sizeof(struct virtio_net_hdr)) 1049 return -EINVAL; 1050 1051 q->vnet_hdr_sz = s; 1052 return 0; 1053 1054 case TUNGETVNETLE: 1055 s = !!(q->flags & TAP_VNET_LE); 1056 if (put_user(s, sp)) 1057 return -EFAULT; 1058 return 0; 1059 1060 case TUNSETVNETLE: 1061 if (get_user(s, sp)) 1062 return -EFAULT; 1063 if (s) 1064 q->flags |= TAP_VNET_LE; 1065 else 1066 q->flags &= ~TAP_VNET_LE; 1067 return 0; 1068 1069 case TUNGETVNETBE: 1070 return tap_get_vnet_be(q, sp); 1071 1072 case TUNSETVNETBE: 1073 return tap_set_vnet_be(q, sp); 1074 1075 case TUNSETOFFLOAD: 1076 /* let the user check for future flags */ 1077 if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 | 1078 TUN_F_TSO_ECN | TUN_F_UFO)) 1079 return -EINVAL; 1080 1081 rtnl_lock(); 1082 ret = set_offload(q, arg); 1083 rtnl_unlock(); 1084 return ret; 1085 1086 case SIOCGIFHWADDR: 1087 rtnl_lock(); 1088 tap = tap_get_tap_dev(q); 1089 if (!tap) { 1090 rtnl_unlock(); 1091 return -ENOLINK; 1092 } 1093 ret = 0; 1094 u = tap->dev->type; 1095 if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) || 1096 copy_to_user(&ifr->ifr_hwaddr.sa_data, tap->dev->dev_addr, ETH_ALEN) || 1097 put_user(u, &ifr->ifr_hwaddr.sa_family)) 1098 ret = -EFAULT; 1099 tap_put_tap_dev(tap); 1100 rtnl_unlock(); 1101 return ret; 1102 1103 case SIOCSIFHWADDR: 1104 if (copy_from_user(&sa, &ifr->ifr_hwaddr, sizeof(sa))) 1105 return -EFAULT; 1106 rtnl_lock(); 1107 tap = tap_get_tap_dev(q); 1108 if (!tap) { 1109 rtnl_unlock(); 1110 return -ENOLINK; 1111 } 1112 ret = dev_set_mac_address(tap->dev, &sa); 1113 tap_put_tap_dev(tap); 1114 rtnl_unlock(); 1115 return ret; 1116 1117 default: 1118 return -EINVAL; 1119 } 1120 } 1121 1122 #ifdef CONFIG_COMPAT 1123 static long tap_compat_ioctl(struct file *file, unsigned int cmd, 1124 unsigned long arg) 1125 { 1126 return tap_ioctl(file, cmd, (unsigned long)compat_ptr(arg)); 1127 } 1128 #endif 1129 1130 const struct file_operations tap_fops = { 1131 .owner = THIS_MODULE, 1132 .open = tap_open, 1133 .release = tap_release, 1134 .read_iter = tap_read_iter, 1135 .write_iter = tap_write_iter, 1136 .poll = tap_poll, 1137 .llseek = no_llseek, 1138 .unlocked_ioctl = tap_ioctl, 1139 #ifdef CONFIG_COMPAT 1140 .compat_ioctl = tap_compat_ioctl, 1141 #endif 1142 }; 1143 1144 static int tap_sendmsg(struct socket *sock, struct msghdr *m, 1145 size_t total_len) 1146 { 1147 struct tap_queue *q = container_of(sock, struct tap_queue, sock); 1148 return tap_get_user(q, m, &m->msg_iter, m->msg_flags & MSG_DONTWAIT); 1149 } 1150 1151 static int tap_recvmsg(struct socket *sock, struct msghdr *m, 1152 size_t total_len, int flags) 1153 { 1154 struct tap_queue *q = container_of(sock, struct tap_queue, sock); 1155 int ret; 1156 if (flags & ~(MSG_DONTWAIT|MSG_TRUNC)) 1157 return -EINVAL; 1158 ret = tap_do_read(q, &m->msg_iter, flags & MSG_DONTWAIT); 1159 if (ret > total_len) { 1160 m->msg_flags |= MSG_TRUNC; 1161 ret = flags & MSG_TRUNC ? ret : total_len; 1162 } 1163 return ret; 1164 } 1165 1166 static int tap_peek_len(struct socket *sock) 1167 { 1168 struct tap_queue *q = container_of(sock, struct tap_queue, 1169 sock); 1170 return skb_array_peek_len(&q->skb_array); 1171 } 1172 1173 /* Ops structure to mimic raw sockets with tun */ 1174 static const struct proto_ops tap_socket_ops = { 1175 .sendmsg = tap_sendmsg, 1176 .recvmsg = tap_recvmsg, 1177 .peek_len = tap_peek_len, 1178 }; 1179 1180 /* Get an underlying socket object from tun file. Returns error unless file is 1181 * attached to a device. The returned object works like a packet socket, it 1182 * can be used for sock_sendmsg/sock_recvmsg. The caller is responsible for 1183 * holding a reference to the file for as long as the socket is in use. */ 1184 struct socket *tap_get_socket(struct file *file) 1185 { 1186 struct tap_queue *q; 1187 if (file->f_op != &tap_fops) 1188 return ERR_PTR(-EINVAL); 1189 q = file->private_data; 1190 if (!q) 1191 return ERR_PTR(-EBADFD); 1192 return &q->sock; 1193 } 1194 EXPORT_SYMBOL_GPL(tap_get_socket); 1195 1196 int tap_queue_resize(struct tap_dev *tap) 1197 { 1198 struct net_device *dev = tap->dev; 1199 struct tap_queue *q; 1200 struct skb_array **arrays; 1201 int n = tap->numqueues; 1202 int ret, i = 0; 1203 1204 arrays = kmalloc(sizeof *arrays * n, GFP_KERNEL); 1205 if (!arrays) 1206 return -ENOMEM; 1207 1208 list_for_each_entry(q, &tap->queue_list, next) 1209 arrays[i++] = &q->skb_array; 1210 1211 ret = skb_array_resize_multiple(arrays, n, 1212 dev->tx_queue_len, GFP_KERNEL); 1213 1214 kfree(arrays); 1215 return ret; 1216 } 1217 EXPORT_SYMBOL_GPL(tap_queue_resize); 1218 1219 static int tap_list_add(dev_t major, const char *device_name) 1220 { 1221 struct major_info *tap_major; 1222 1223 tap_major = kzalloc(sizeof(*tap_major), GFP_ATOMIC); 1224 if (!tap_major) 1225 return -ENOMEM; 1226 1227 tap_major->major = MAJOR(major); 1228 1229 idr_init(&tap_major->minor_idr); 1230 mutex_init(&tap_major->minor_lock); 1231 1232 tap_major->device_name = device_name; 1233 1234 list_add_tail_rcu(&tap_major->next, &major_list); 1235 return 0; 1236 } 1237 1238 int tap_create_cdev(struct cdev *tap_cdev, 1239 dev_t *tap_major, const char *device_name) 1240 { 1241 int err; 1242 1243 err = alloc_chrdev_region(tap_major, 0, TAP_NUM_DEVS, device_name); 1244 if (err) 1245 goto out1; 1246 1247 cdev_init(tap_cdev, &tap_fops); 1248 err = cdev_add(tap_cdev, *tap_major, TAP_NUM_DEVS); 1249 if (err) 1250 goto out2; 1251 1252 err = tap_list_add(*tap_major, device_name); 1253 if (err) 1254 goto out3; 1255 1256 return 0; 1257 1258 out3: 1259 cdev_del(tap_cdev); 1260 out2: 1261 unregister_chrdev_region(*tap_major, TAP_NUM_DEVS); 1262 out1: 1263 return err; 1264 } 1265 EXPORT_SYMBOL_GPL(tap_create_cdev); 1266 1267 void tap_destroy_cdev(dev_t major, struct cdev *tap_cdev) 1268 { 1269 struct major_info *tap_major, *tmp; 1270 1271 cdev_del(tap_cdev); 1272 unregister_chrdev_region(major, TAP_NUM_DEVS); 1273 list_for_each_entry_safe(tap_major, tmp, &major_list, next) { 1274 if (tap_major->major == MAJOR(major)) { 1275 idr_destroy(&tap_major->minor_idr); 1276 list_del_rcu(&tap_major->next); 1277 kfree_rcu(tap_major, rcu); 1278 } 1279 } 1280 } 1281 EXPORT_SYMBOL_GPL(tap_destroy_cdev); 1282 1283 MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>"); 1284 MODULE_AUTHOR("Sainath Grandhi <sainath.grandhi@intel.com>"); 1285 MODULE_LICENSE("GPL"); 1286