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 spinlock_t 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 = READ_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 spin_lock(&tap_major->minor_lock); 420 retval = idr_alloc(&tap_major->minor_idr, tap, 1, TAP_NUM_DEVS, GFP_ATOMIC); 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 spin_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 spin_lock(&tap_major->minor_lock); 446 if (tap->minor) { 447 idr_remove(&tap_major->minor_idr, tap->minor); 448 tap->minor = 0; 449 } 450 spin_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 spin_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 spin_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 if (skb_array_init(&q->skb_array, tap->dev->tx_queue_len, GFP_KERNEL)) { 521 sk_free(&q->sk); 522 goto err; 523 } 524 525 RCU_INIT_POINTER(q->sock.wq, &q->wq); 526 init_waitqueue_head(&q->wq.wait); 527 q->sock.type = SOCK_RAW; 528 q->sock.state = SS_CONNECTED; 529 q->sock.file = file; 530 q->sock.ops = &tap_socket_ops; 531 sock_init_data(&q->sock, &q->sk); 532 q->sk.sk_write_space = tap_sock_write_space; 533 q->sk.sk_destruct = tap_sock_destruct; 534 q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP; 535 q->vnet_hdr_sz = sizeof(struct virtio_net_hdr); 536 537 /* 538 * so far only KVM virtio_net uses tap, enable zero copy between 539 * guest kernel and host kernel when lower device supports zerocopy 540 * 541 * The macvlan supports zerocopy iff the lower device supports zero 542 * copy so we don't have to look at the lower device directly. 543 */ 544 if ((tap->dev->features & NETIF_F_HIGHDMA) && (tap->dev->features & NETIF_F_SG)) 545 sock_set_flag(&q->sk, SOCK_ZEROCOPY); 546 547 err = tap_set_queue(tap, file, q); 548 if (err) { 549 /* tap_sock_destruct() will take care of freeing skb_array */ 550 goto err_put; 551 } 552 553 dev_put(tap->dev); 554 555 rtnl_unlock(); 556 return err; 557 558 err_put: 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, struct sk_buff *skb) 828 { 829 DEFINE_WAIT(wait); 830 ssize_t ret = 0; 831 832 if (!iov_iter_count(to)) { 833 if (skb) 834 kfree_skb(skb); 835 return 0; 836 } 837 838 if (skb) 839 goto put; 840 841 while (1) { 842 if (!noblock) 843 prepare_to_wait(sk_sleep(&q->sk), &wait, 844 TASK_INTERRUPTIBLE); 845 846 /* Read frames from the queue */ 847 skb = skb_array_consume(&q->skb_array); 848 if (skb) 849 break; 850 if (noblock) { 851 ret = -EAGAIN; 852 break; 853 } 854 if (signal_pending(current)) { 855 ret = -ERESTARTSYS; 856 break; 857 } 858 /* Nothing to read, let's sleep */ 859 schedule(); 860 } 861 if (!noblock) 862 finish_wait(sk_sleep(&q->sk), &wait); 863 864 put: 865 if (skb) { 866 ret = tap_put_user(q, skb, to); 867 if (unlikely(ret < 0)) 868 kfree_skb(skb); 869 else 870 consume_skb(skb); 871 } 872 return ret; 873 } 874 875 static ssize_t tap_read_iter(struct kiocb *iocb, struct iov_iter *to) 876 { 877 struct file *file = iocb->ki_filp; 878 struct tap_queue *q = file->private_data; 879 ssize_t len = iov_iter_count(to), ret; 880 881 ret = tap_do_read(q, to, file->f_flags & O_NONBLOCK, NULL); 882 ret = min_t(ssize_t, ret, len); 883 if (ret > 0) 884 iocb->ki_pos = ret; 885 return ret; 886 } 887 888 static struct tap_dev *tap_get_tap_dev(struct tap_queue *q) 889 { 890 struct tap_dev *tap; 891 892 ASSERT_RTNL(); 893 tap = rtnl_dereference(q->tap); 894 if (tap) 895 dev_hold(tap->dev); 896 897 return tap; 898 } 899 900 static void tap_put_tap_dev(struct tap_dev *tap) 901 { 902 dev_put(tap->dev); 903 } 904 905 static int tap_ioctl_set_queue(struct file *file, unsigned int flags) 906 { 907 struct tap_queue *q = file->private_data; 908 struct tap_dev *tap; 909 int ret; 910 911 tap = tap_get_tap_dev(q); 912 if (!tap) 913 return -EINVAL; 914 915 if (flags & IFF_ATTACH_QUEUE) 916 ret = tap_enable_queue(tap, file, q); 917 else if (flags & IFF_DETACH_QUEUE) 918 ret = tap_disable_queue(q); 919 else 920 ret = -EINVAL; 921 922 tap_put_tap_dev(tap); 923 return ret; 924 } 925 926 static int set_offload(struct tap_queue *q, unsigned long arg) 927 { 928 struct tap_dev *tap; 929 netdev_features_t features; 930 netdev_features_t feature_mask = 0; 931 932 tap = rtnl_dereference(q->tap); 933 if (!tap) 934 return -ENOLINK; 935 936 features = tap->dev->features; 937 938 if (arg & TUN_F_CSUM) { 939 feature_mask = NETIF_F_HW_CSUM; 940 941 if (arg & (TUN_F_TSO4 | TUN_F_TSO6)) { 942 if (arg & TUN_F_TSO_ECN) 943 feature_mask |= NETIF_F_TSO_ECN; 944 if (arg & TUN_F_TSO4) 945 feature_mask |= NETIF_F_TSO; 946 if (arg & TUN_F_TSO6) 947 feature_mask |= NETIF_F_TSO6; 948 } 949 } 950 951 /* tun/tap driver inverts the usage for TSO offloads, where 952 * setting the TSO bit means that the userspace wants to 953 * accept TSO frames and turning it off means that user space 954 * does not support TSO. 955 * For tap, we have to invert it to mean the same thing. 956 * When user space turns off TSO, we turn off GSO/LRO so that 957 * user-space will not receive TSO frames. 958 */ 959 if (feature_mask & (NETIF_F_TSO | NETIF_F_TSO6)) 960 features |= RX_OFFLOADS; 961 else 962 features &= ~RX_OFFLOADS; 963 964 /* tap_features are the same as features on tun/tap and 965 * reflect user expectations. 966 */ 967 tap->tap_features = feature_mask; 968 if (tap->update_features) 969 tap->update_features(tap, features); 970 971 return 0; 972 } 973 974 /* 975 * provide compatibility with generic tun/tap interface 976 */ 977 static long tap_ioctl(struct file *file, unsigned int cmd, 978 unsigned long arg) 979 { 980 struct tap_queue *q = file->private_data; 981 struct tap_dev *tap; 982 void __user *argp = (void __user *)arg; 983 struct ifreq __user *ifr = argp; 984 unsigned int __user *up = argp; 985 unsigned short u; 986 int __user *sp = argp; 987 struct sockaddr sa; 988 int s; 989 int ret; 990 991 switch (cmd) { 992 case TUNSETIFF: 993 /* ignore the name, just look at flags */ 994 if (get_user(u, &ifr->ifr_flags)) 995 return -EFAULT; 996 997 ret = 0; 998 if ((u & ~TAP_IFFEATURES) != (IFF_NO_PI | IFF_TAP)) 999 ret = -EINVAL; 1000 else 1001 q->flags = (q->flags & ~TAP_IFFEATURES) | u; 1002 1003 return ret; 1004 1005 case TUNGETIFF: 1006 rtnl_lock(); 1007 tap = tap_get_tap_dev(q); 1008 if (!tap) { 1009 rtnl_unlock(); 1010 return -ENOLINK; 1011 } 1012 1013 ret = 0; 1014 u = q->flags; 1015 if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) || 1016 put_user(u, &ifr->ifr_flags)) 1017 ret = -EFAULT; 1018 tap_put_tap_dev(tap); 1019 rtnl_unlock(); 1020 return ret; 1021 1022 case TUNSETQUEUE: 1023 if (get_user(u, &ifr->ifr_flags)) 1024 return -EFAULT; 1025 rtnl_lock(); 1026 ret = tap_ioctl_set_queue(file, u); 1027 rtnl_unlock(); 1028 return ret; 1029 1030 case TUNGETFEATURES: 1031 if (put_user(IFF_TAP | IFF_NO_PI | TAP_IFFEATURES, up)) 1032 return -EFAULT; 1033 return 0; 1034 1035 case TUNSETSNDBUF: 1036 if (get_user(s, sp)) 1037 return -EFAULT; 1038 if (s <= 0) 1039 return -EINVAL; 1040 1041 q->sk.sk_sndbuf = s; 1042 return 0; 1043 1044 case TUNGETVNETHDRSZ: 1045 s = q->vnet_hdr_sz; 1046 if (put_user(s, sp)) 1047 return -EFAULT; 1048 return 0; 1049 1050 case TUNSETVNETHDRSZ: 1051 if (get_user(s, sp)) 1052 return -EFAULT; 1053 if (s < (int)sizeof(struct virtio_net_hdr)) 1054 return -EINVAL; 1055 1056 q->vnet_hdr_sz = s; 1057 return 0; 1058 1059 case TUNGETVNETLE: 1060 s = !!(q->flags & TAP_VNET_LE); 1061 if (put_user(s, sp)) 1062 return -EFAULT; 1063 return 0; 1064 1065 case TUNSETVNETLE: 1066 if (get_user(s, sp)) 1067 return -EFAULT; 1068 if (s) 1069 q->flags |= TAP_VNET_LE; 1070 else 1071 q->flags &= ~TAP_VNET_LE; 1072 return 0; 1073 1074 case TUNGETVNETBE: 1075 return tap_get_vnet_be(q, sp); 1076 1077 case TUNSETVNETBE: 1078 return tap_set_vnet_be(q, sp); 1079 1080 case TUNSETOFFLOAD: 1081 /* let the user check for future flags */ 1082 if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 | 1083 TUN_F_TSO_ECN | TUN_F_UFO)) 1084 return -EINVAL; 1085 1086 rtnl_lock(); 1087 ret = set_offload(q, arg); 1088 rtnl_unlock(); 1089 return ret; 1090 1091 case SIOCGIFHWADDR: 1092 rtnl_lock(); 1093 tap = tap_get_tap_dev(q); 1094 if (!tap) { 1095 rtnl_unlock(); 1096 return -ENOLINK; 1097 } 1098 ret = 0; 1099 u = tap->dev->type; 1100 if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) || 1101 copy_to_user(&ifr->ifr_hwaddr.sa_data, tap->dev->dev_addr, ETH_ALEN) || 1102 put_user(u, &ifr->ifr_hwaddr.sa_family)) 1103 ret = -EFAULT; 1104 tap_put_tap_dev(tap); 1105 rtnl_unlock(); 1106 return ret; 1107 1108 case SIOCSIFHWADDR: 1109 if (copy_from_user(&sa, &ifr->ifr_hwaddr, sizeof(sa))) 1110 return -EFAULT; 1111 rtnl_lock(); 1112 tap = tap_get_tap_dev(q); 1113 if (!tap) { 1114 rtnl_unlock(); 1115 return -ENOLINK; 1116 } 1117 ret = dev_set_mac_address(tap->dev, &sa); 1118 tap_put_tap_dev(tap); 1119 rtnl_unlock(); 1120 return ret; 1121 1122 default: 1123 return -EINVAL; 1124 } 1125 } 1126 1127 #ifdef CONFIG_COMPAT 1128 static long tap_compat_ioctl(struct file *file, unsigned int cmd, 1129 unsigned long arg) 1130 { 1131 return tap_ioctl(file, cmd, (unsigned long)compat_ptr(arg)); 1132 } 1133 #endif 1134 1135 static const struct file_operations tap_fops = { 1136 .owner = THIS_MODULE, 1137 .open = tap_open, 1138 .release = tap_release, 1139 .read_iter = tap_read_iter, 1140 .write_iter = tap_write_iter, 1141 .poll = tap_poll, 1142 .llseek = no_llseek, 1143 .unlocked_ioctl = tap_ioctl, 1144 #ifdef CONFIG_COMPAT 1145 .compat_ioctl = tap_compat_ioctl, 1146 #endif 1147 }; 1148 1149 static int tap_sendmsg(struct socket *sock, struct msghdr *m, 1150 size_t total_len) 1151 { 1152 struct tap_queue *q = container_of(sock, struct tap_queue, sock); 1153 return tap_get_user(q, m, &m->msg_iter, m->msg_flags & MSG_DONTWAIT); 1154 } 1155 1156 static int tap_recvmsg(struct socket *sock, struct msghdr *m, 1157 size_t total_len, int flags) 1158 { 1159 struct tap_queue *q = container_of(sock, struct tap_queue, sock); 1160 struct sk_buff *skb = m->msg_control; 1161 int ret; 1162 if (flags & ~(MSG_DONTWAIT|MSG_TRUNC)) { 1163 if (skb) 1164 kfree_skb(skb); 1165 return -EINVAL; 1166 } 1167 ret = tap_do_read(q, &m->msg_iter, flags & MSG_DONTWAIT, skb); 1168 if (ret > total_len) { 1169 m->msg_flags |= MSG_TRUNC; 1170 ret = flags & MSG_TRUNC ? ret : total_len; 1171 } 1172 return ret; 1173 } 1174 1175 static int tap_peek_len(struct socket *sock) 1176 { 1177 struct tap_queue *q = container_of(sock, struct tap_queue, 1178 sock); 1179 return skb_array_peek_len(&q->skb_array); 1180 } 1181 1182 /* Ops structure to mimic raw sockets with tun */ 1183 static const struct proto_ops tap_socket_ops = { 1184 .sendmsg = tap_sendmsg, 1185 .recvmsg = tap_recvmsg, 1186 .peek_len = tap_peek_len, 1187 }; 1188 1189 /* Get an underlying socket object from tun file. Returns error unless file is 1190 * attached to a device. The returned object works like a packet socket, it 1191 * can be used for sock_sendmsg/sock_recvmsg. The caller is responsible for 1192 * holding a reference to the file for as long as the socket is in use. */ 1193 struct socket *tap_get_socket(struct file *file) 1194 { 1195 struct tap_queue *q; 1196 if (file->f_op != &tap_fops) 1197 return ERR_PTR(-EINVAL); 1198 q = file->private_data; 1199 if (!q) 1200 return ERR_PTR(-EBADFD); 1201 return &q->sock; 1202 } 1203 EXPORT_SYMBOL_GPL(tap_get_socket); 1204 1205 struct skb_array *tap_get_skb_array(struct file *file) 1206 { 1207 struct tap_queue *q; 1208 1209 if (file->f_op != &tap_fops) 1210 return ERR_PTR(-EINVAL); 1211 q = file->private_data; 1212 if (!q) 1213 return ERR_PTR(-EBADFD); 1214 return &q->skb_array; 1215 } 1216 EXPORT_SYMBOL_GPL(tap_get_skb_array); 1217 1218 int tap_queue_resize(struct tap_dev *tap) 1219 { 1220 struct net_device *dev = tap->dev; 1221 struct tap_queue *q; 1222 struct skb_array **arrays; 1223 int n = tap->numqueues; 1224 int ret, i = 0; 1225 1226 arrays = kmalloc_array(n, sizeof(*arrays), GFP_KERNEL); 1227 if (!arrays) 1228 return -ENOMEM; 1229 1230 list_for_each_entry(q, &tap->queue_list, next) 1231 arrays[i++] = &q->skb_array; 1232 1233 ret = skb_array_resize_multiple(arrays, n, 1234 dev->tx_queue_len, GFP_KERNEL); 1235 1236 kfree(arrays); 1237 return ret; 1238 } 1239 EXPORT_SYMBOL_GPL(tap_queue_resize); 1240 1241 static int tap_list_add(dev_t major, const char *device_name) 1242 { 1243 struct major_info *tap_major; 1244 1245 tap_major = kzalloc(sizeof(*tap_major), GFP_ATOMIC); 1246 if (!tap_major) 1247 return -ENOMEM; 1248 1249 tap_major->major = MAJOR(major); 1250 1251 idr_init(&tap_major->minor_idr); 1252 spin_lock_init(&tap_major->minor_lock); 1253 1254 tap_major->device_name = device_name; 1255 1256 list_add_tail_rcu(&tap_major->next, &major_list); 1257 return 0; 1258 } 1259 1260 int tap_create_cdev(struct cdev *tap_cdev, dev_t *tap_major, 1261 const char *device_name, struct module *module) 1262 { 1263 int err; 1264 1265 err = alloc_chrdev_region(tap_major, 0, TAP_NUM_DEVS, device_name); 1266 if (err) 1267 goto out1; 1268 1269 cdev_init(tap_cdev, &tap_fops); 1270 tap_cdev->owner = module; 1271 err = cdev_add(tap_cdev, *tap_major, TAP_NUM_DEVS); 1272 if (err) 1273 goto out2; 1274 1275 err = tap_list_add(*tap_major, device_name); 1276 if (err) 1277 goto out3; 1278 1279 return 0; 1280 1281 out3: 1282 cdev_del(tap_cdev); 1283 out2: 1284 unregister_chrdev_region(*tap_major, TAP_NUM_DEVS); 1285 out1: 1286 return err; 1287 } 1288 EXPORT_SYMBOL_GPL(tap_create_cdev); 1289 1290 void tap_destroy_cdev(dev_t major, struct cdev *tap_cdev) 1291 { 1292 struct major_info *tap_major, *tmp; 1293 1294 cdev_del(tap_cdev); 1295 unregister_chrdev_region(major, TAP_NUM_DEVS); 1296 list_for_each_entry_safe(tap_major, tmp, &major_list, next) { 1297 if (tap_major->major == MAJOR(major)) { 1298 idr_destroy(&tap_major->minor_idr); 1299 list_del_rcu(&tap_major->next); 1300 kfree_rcu(tap_major, rcu); 1301 } 1302 } 1303 } 1304 EXPORT_SYMBOL_GPL(tap_destroy_cdev); 1305 1306 MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>"); 1307 MODULE_AUTHOR("Sainath Grandhi <sainath.grandhi@intel.com>"); 1308 MODULE_LICENSE("GPL"); 1309