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 33 static 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 39 static 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 49 static 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 64 static inline bool tap_legacy_is_little_endian(struct tap_queue *q) 65 { 66 return virtio_legacy_is_little_endian(); 67 } 68 69 static long tap_get_vnet_be(struct tap_queue *q, int __user *argp) 70 { 71 return -EINVAL; 72 } 73 74 static 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 80 static 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 86 static 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 91 static 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 96 static 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) 103 104 static LIST_HEAD(major_list); 105 106 struct 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 128 116 117 static 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) 121 122 static 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 */ 143 144 static 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++; 160 out: 161 return err; 162 } 163 164 /* Requires RTNL */ 165 static 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 } 186 187 static 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 */ 222 static 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 */ 252 static 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 } 286 287 single: 288 queue = rcu_dereference(tap->taps[0]); 289 out: 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 */ 298 void 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 } 316 EXPORT_SYMBOL_GPL(tap_del_queues); 317 318 rx_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 enum skb_drop_reason drop_reason; 326 327 tap = tap_dev_get_rcu(dev); 328 if (!tap) 329 return RX_HANDLER_PASS; 330 331 q = tap_get_queue(tap, skb); 332 if (!q) 333 return RX_HANDLER_PASS; 334 335 skb_push(skb, ETH_HLEN); 336 337 /* Apply the forward feature mask so that we perform segmentation 338 * according to users wishes. This only works if VNET_HDR is 339 * enabled. 340 */ 341 if (q->flags & IFF_VNET_HDR) 342 features |= tap->tap_features; 343 if (netif_needs_gso(skb, features)) { 344 struct sk_buff *segs = __skb_gso_segment(skb, features, false); 345 struct sk_buff *next; 346 347 if (IS_ERR(segs)) { 348 drop_reason = SKB_DROP_REASON_SKB_GSO_SEG; 349 goto drop; 350 } 351 352 if (!segs) { 353 if (ptr_ring_produce(&q->ring, skb)) { 354 drop_reason = SKB_DROP_REASON_FULL_RING; 355 goto drop; 356 } 357 goto wake_up; 358 } 359 360 consume_skb(skb); 361 skb_list_walk_safe(segs, skb, next) { 362 skb_mark_not_on_list(skb); 363 if (ptr_ring_produce(&q->ring, skb)) { 364 drop_reason = SKB_DROP_REASON_FULL_RING; 365 kfree_skb_reason(skb, drop_reason); 366 kfree_skb_list_reason(next, drop_reason); 367 break; 368 } 369 } 370 } else { 371 /* If we receive a partial checksum and the tap side 372 * doesn't support checksum offload, compute the checksum. 373 * Note: it doesn't matter which checksum feature to 374 * check, we either support them all or none. 375 */ 376 if (skb->ip_summed == CHECKSUM_PARTIAL && 377 !(features & NETIF_F_CSUM_MASK) && 378 skb_checksum_help(skb)) { 379 drop_reason = SKB_DROP_REASON_SKB_CSUM; 380 goto drop; 381 } 382 if (ptr_ring_produce(&q->ring, skb)) { 383 drop_reason = SKB_DROP_REASON_FULL_RING; 384 goto drop; 385 } 386 } 387 388 wake_up: 389 wake_up_interruptible_poll(sk_sleep(&q->sk), EPOLLIN | EPOLLRDNORM | EPOLLRDBAND); 390 return RX_HANDLER_CONSUMED; 391 392 drop: 393 /* Count errors/drops only here, thus don't care about args. */ 394 if (tap->count_rx_dropped) 395 tap->count_rx_dropped(tap); 396 kfree_skb_reason(skb, drop_reason); 397 return RX_HANDLER_CONSUMED; 398 } 399 EXPORT_SYMBOL_GPL(tap_handle_frame); 400 401 static struct major_info *tap_get_major(int major) 402 { 403 struct major_info *tap_major; 404 405 list_for_each_entry_rcu(tap_major, &major_list, next) { 406 if (tap_major->major == major) 407 return tap_major; 408 } 409 410 return NULL; 411 } 412 413 int tap_get_minor(dev_t major, struct tap_dev *tap) 414 { 415 int retval = -ENOMEM; 416 struct major_info *tap_major; 417 418 rcu_read_lock(); 419 tap_major = tap_get_major(MAJOR(major)); 420 if (!tap_major) { 421 retval = -EINVAL; 422 goto unlock; 423 } 424 425 spin_lock(&tap_major->minor_lock); 426 retval = idr_alloc(&tap_major->minor_idr, tap, 1, TAP_NUM_DEVS, GFP_ATOMIC); 427 if (retval >= 0) { 428 tap->minor = retval; 429 } else if (retval == -ENOSPC) { 430 netdev_err(tap->dev, "Too many tap devices\n"); 431 retval = -EINVAL; 432 } 433 spin_unlock(&tap_major->minor_lock); 434 435 unlock: 436 rcu_read_unlock(); 437 return retval < 0 ? retval : 0; 438 } 439 EXPORT_SYMBOL_GPL(tap_get_minor); 440 441 void tap_free_minor(dev_t major, struct tap_dev *tap) 442 { 443 struct major_info *tap_major; 444 445 rcu_read_lock(); 446 tap_major = tap_get_major(MAJOR(major)); 447 if (!tap_major) { 448 goto unlock; 449 } 450 451 spin_lock(&tap_major->minor_lock); 452 if (tap->minor) { 453 idr_remove(&tap_major->minor_idr, tap->minor); 454 tap->minor = 0; 455 } 456 spin_unlock(&tap_major->minor_lock); 457 458 unlock: 459 rcu_read_unlock(); 460 } 461 EXPORT_SYMBOL_GPL(tap_free_minor); 462 463 static struct tap_dev *dev_get_by_tap_file(int major, int minor) 464 { 465 struct net_device *dev = NULL; 466 struct tap_dev *tap; 467 struct major_info *tap_major; 468 469 rcu_read_lock(); 470 tap_major = tap_get_major(major); 471 if (!tap_major) { 472 tap = NULL; 473 goto unlock; 474 } 475 476 spin_lock(&tap_major->minor_lock); 477 tap = idr_find(&tap_major->minor_idr, minor); 478 if (tap) { 479 dev = tap->dev; 480 dev_hold(dev); 481 } 482 spin_unlock(&tap_major->minor_lock); 483 484 unlock: 485 rcu_read_unlock(); 486 return tap; 487 } 488 489 static void tap_sock_write_space(struct sock *sk) 490 { 491 wait_queue_head_t *wqueue; 492 493 if (!sock_writeable(sk) || 494 !test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags)) 495 return; 496 497 wqueue = sk_sleep(sk); 498 if (wqueue && waitqueue_active(wqueue)) 499 wake_up_interruptible_poll(wqueue, EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND); 500 } 501 502 static void tap_sock_destruct(struct sock *sk) 503 { 504 struct tap_queue *q = container_of(sk, struct tap_queue, sk); 505 506 ptr_ring_cleanup(&q->ring, __skb_array_destroy_skb); 507 } 508 509 static int tap_open(struct inode *inode, struct file *file) 510 { 511 struct net *net = current->nsproxy->net_ns; 512 struct tap_dev *tap; 513 struct tap_queue *q; 514 int err = -ENODEV; 515 516 rtnl_lock(); 517 tap = dev_get_by_tap_file(imajor(inode), iminor(inode)); 518 if (!tap) 519 goto err; 520 521 err = -ENOMEM; 522 q = (struct tap_queue *)sk_alloc(net, AF_UNSPEC, GFP_KERNEL, 523 &tap_proto, 0); 524 if (!q) 525 goto err; 526 if (ptr_ring_init(&q->ring, tap->dev->tx_queue_len, GFP_KERNEL)) { 527 sk_free(&q->sk); 528 goto err; 529 } 530 531 init_waitqueue_head(&q->sock.wq.wait); 532 q->sock.type = SOCK_RAW; 533 q->sock.state = SS_CONNECTED; 534 q->sock.file = file; 535 q->sock.ops = &tap_socket_ops; 536 sock_init_data(&q->sock, &q->sk); 537 q->sk.sk_write_space = tap_sock_write_space; 538 q->sk.sk_destruct = tap_sock_destruct; 539 q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP; 540 q->vnet_hdr_sz = sizeof(struct virtio_net_hdr); 541 542 /* 543 * so far only KVM virtio_net uses tap, enable zero copy between 544 * guest kernel and host kernel when lower device supports zerocopy 545 * 546 * The macvlan supports zerocopy iff the lower device supports zero 547 * copy so we don't have to look at the lower device directly. 548 */ 549 if ((tap->dev->features & NETIF_F_HIGHDMA) && (tap->dev->features & NETIF_F_SG)) 550 sock_set_flag(&q->sk, SOCK_ZEROCOPY); 551 552 err = tap_set_queue(tap, file, q); 553 if (err) { 554 /* tap_sock_destruct() will take care of freeing ptr_ring */ 555 goto err_put; 556 } 557 558 dev_put(tap->dev); 559 560 rtnl_unlock(); 561 return err; 562 563 err_put: 564 sock_put(&q->sk); 565 err: 566 if (tap) 567 dev_put(tap->dev); 568 569 rtnl_unlock(); 570 return err; 571 } 572 573 static int tap_release(struct inode *inode, struct file *file) 574 { 575 struct tap_queue *q = file->private_data; 576 tap_put_queue(q); 577 return 0; 578 } 579 580 static __poll_t tap_poll(struct file *file, poll_table *wait) 581 { 582 struct tap_queue *q = file->private_data; 583 __poll_t mask = EPOLLERR; 584 585 if (!q) 586 goto out; 587 588 mask = 0; 589 poll_wait(file, &q->sock.wq.wait, wait); 590 591 if (!ptr_ring_empty(&q->ring)) 592 mask |= EPOLLIN | EPOLLRDNORM; 593 594 if (sock_writeable(&q->sk) || 595 (!test_and_set_bit(SOCKWQ_ASYNC_NOSPACE, &q->sock.flags) && 596 sock_writeable(&q->sk))) 597 mask |= EPOLLOUT | EPOLLWRNORM; 598 599 out: 600 return mask; 601 } 602 603 static inline struct sk_buff *tap_alloc_skb(struct sock *sk, size_t prepad, 604 size_t len, size_t linear, 605 int noblock, int *err) 606 { 607 struct sk_buff *skb; 608 609 /* Under a page? Don't bother with paged skb. */ 610 if (prepad + len < PAGE_SIZE || !linear) 611 linear = len; 612 613 skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock, 614 err, 0); 615 if (!skb) 616 return NULL; 617 618 skb_reserve(skb, prepad); 619 skb_put(skb, linear); 620 skb->data_len = len - linear; 621 skb->len += len - linear; 622 623 return skb; 624 } 625 626 /* Neighbour code has some assumptions on HH_DATA_MOD alignment */ 627 #define TAP_RESERVE HH_DATA_OFF(ETH_HLEN) 628 629 /* Get packet from user space buffer */ 630 static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, 631 struct iov_iter *from, int noblock) 632 { 633 int good_linear = SKB_MAX_HEAD(TAP_RESERVE); 634 struct sk_buff *skb; 635 struct tap_dev *tap; 636 unsigned long total_len = iov_iter_count(from); 637 unsigned long len = total_len; 638 int err; 639 struct virtio_net_hdr vnet_hdr = { 0 }; 640 int vnet_hdr_len = 0; 641 int copylen = 0; 642 int depth; 643 bool zerocopy = false; 644 size_t linear; 645 enum skb_drop_reason drop_reason; 646 647 if (q->flags & IFF_VNET_HDR) { 648 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz); 649 650 err = -EINVAL; 651 if (len < vnet_hdr_len) 652 goto err; 653 len -= vnet_hdr_len; 654 655 err = -EFAULT; 656 if (!copy_from_iter_full(&vnet_hdr, sizeof(vnet_hdr), from)) 657 goto err; 658 iov_iter_advance(from, vnet_hdr_len - sizeof(vnet_hdr)); 659 if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) && 660 tap16_to_cpu(q, vnet_hdr.csum_start) + 661 tap16_to_cpu(q, vnet_hdr.csum_offset) + 2 > 662 tap16_to_cpu(q, vnet_hdr.hdr_len)) 663 vnet_hdr.hdr_len = cpu_to_tap16(q, 664 tap16_to_cpu(q, vnet_hdr.csum_start) + 665 tap16_to_cpu(q, vnet_hdr.csum_offset) + 2); 666 err = -EINVAL; 667 if (tap16_to_cpu(q, vnet_hdr.hdr_len) > len) 668 goto err; 669 } 670 671 err = -EINVAL; 672 if (unlikely(len < ETH_HLEN)) 673 goto err; 674 675 if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) { 676 struct iov_iter i; 677 678 copylen = vnet_hdr.hdr_len ? 679 tap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN; 680 if (copylen > good_linear) 681 copylen = good_linear; 682 else if (copylen < ETH_HLEN) 683 copylen = ETH_HLEN; 684 linear = copylen; 685 i = *from; 686 iov_iter_advance(&i, copylen); 687 if (iov_iter_npages(&i, INT_MAX) <= MAX_SKB_FRAGS) 688 zerocopy = true; 689 } 690 691 if (!zerocopy) { 692 copylen = len; 693 linear = tap16_to_cpu(q, vnet_hdr.hdr_len); 694 if (linear > good_linear) 695 linear = good_linear; 696 else if (linear < ETH_HLEN) 697 linear = ETH_HLEN; 698 } 699 700 skb = tap_alloc_skb(&q->sk, TAP_RESERVE, copylen, 701 linear, noblock, &err); 702 if (!skb) 703 goto err; 704 705 if (zerocopy) 706 err = zerocopy_sg_from_iter(skb, from); 707 else 708 err = skb_copy_datagram_from_iter(skb, 0, from, len); 709 710 if (err) { 711 drop_reason = SKB_DROP_REASON_SKB_UCOPY_FAULT; 712 goto err_kfree; 713 } 714 715 skb_set_network_header(skb, ETH_HLEN); 716 skb_reset_mac_header(skb); 717 skb->protocol = eth_hdr(skb)->h_proto; 718 719 if (vnet_hdr_len) { 720 err = virtio_net_hdr_to_skb(skb, &vnet_hdr, 721 tap_is_little_endian(q)); 722 if (err) { 723 drop_reason = SKB_DROP_REASON_DEV_HDR; 724 goto err_kfree; 725 } 726 } 727 728 skb_probe_transport_header(skb); 729 730 /* Move network header to the right position for VLAN tagged packets */ 731 if (eth_type_vlan(skb->protocol) && 732 __vlan_get_protocol(skb, skb->protocol, &depth) != 0) 733 skb_set_network_header(skb, depth); 734 735 rcu_read_lock(); 736 tap = rcu_dereference(q->tap); 737 /* copy skb_ubuf_info for callback when skb has no error */ 738 if (zerocopy) { 739 skb_zcopy_init(skb, msg_control); 740 } else if (msg_control) { 741 struct ubuf_info *uarg = msg_control; 742 uarg->callback(NULL, uarg, false); 743 } 744 745 if (tap) { 746 skb->dev = tap->dev; 747 dev_queue_xmit(skb); 748 } else { 749 kfree_skb(skb); 750 } 751 rcu_read_unlock(); 752 753 return total_len; 754 755 err_kfree: 756 kfree_skb_reason(skb, drop_reason); 757 758 err: 759 rcu_read_lock(); 760 tap = rcu_dereference(q->tap); 761 if (tap && tap->count_tx_dropped) 762 tap->count_tx_dropped(tap); 763 rcu_read_unlock(); 764 765 return err; 766 } 767 768 static ssize_t tap_write_iter(struct kiocb *iocb, struct iov_iter *from) 769 { 770 struct file *file = iocb->ki_filp; 771 struct tap_queue *q = file->private_data; 772 773 return tap_get_user(q, NULL, from, file->f_flags & O_NONBLOCK); 774 } 775 776 /* Put packet to the user space buffer */ 777 static ssize_t tap_put_user(struct tap_queue *q, 778 const struct sk_buff *skb, 779 struct iov_iter *iter) 780 { 781 int ret; 782 int vnet_hdr_len = 0; 783 int vlan_offset = 0; 784 int total; 785 786 if (q->flags & IFF_VNET_HDR) { 787 int vlan_hlen = skb_vlan_tag_present(skb) ? VLAN_HLEN : 0; 788 struct virtio_net_hdr vnet_hdr; 789 790 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz); 791 if (iov_iter_count(iter) < vnet_hdr_len) 792 return -EINVAL; 793 794 if (virtio_net_hdr_from_skb(skb, &vnet_hdr, 795 tap_is_little_endian(q), true, 796 vlan_hlen)) 797 BUG(); 798 799 if (copy_to_iter(&vnet_hdr, sizeof(vnet_hdr), iter) != 800 sizeof(vnet_hdr)) 801 return -EFAULT; 802 803 iov_iter_advance(iter, vnet_hdr_len - sizeof(vnet_hdr)); 804 } 805 total = vnet_hdr_len; 806 total += skb->len; 807 808 if (skb_vlan_tag_present(skb)) { 809 struct { 810 __be16 h_vlan_proto; 811 __be16 h_vlan_TCI; 812 } veth; 813 veth.h_vlan_proto = skb->vlan_proto; 814 veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb)); 815 816 vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto); 817 total += VLAN_HLEN; 818 819 ret = skb_copy_datagram_iter(skb, 0, iter, vlan_offset); 820 if (ret || !iov_iter_count(iter)) 821 goto done; 822 823 ret = copy_to_iter(&veth, sizeof(veth), iter); 824 if (ret != sizeof(veth) || !iov_iter_count(iter)) 825 goto done; 826 } 827 828 ret = skb_copy_datagram_iter(skb, vlan_offset, iter, 829 skb->len - vlan_offset); 830 831 done: 832 return ret ? ret : total; 833 } 834 835 static ssize_t tap_do_read(struct tap_queue *q, 836 struct iov_iter *to, 837 int noblock, struct sk_buff *skb) 838 { 839 DEFINE_WAIT(wait); 840 ssize_t ret = 0; 841 842 if (!iov_iter_count(to)) { 843 kfree_skb(skb); 844 return 0; 845 } 846 847 if (skb) 848 goto put; 849 850 while (1) { 851 if (!noblock) 852 prepare_to_wait(sk_sleep(&q->sk), &wait, 853 TASK_INTERRUPTIBLE); 854 855 /* Read frames from the queue */ 856 skb = ptr_ring_consume(&q->ring); 857 if (skb) 858 break; 859 if (noblock) { 860 ret = -EAGAIN; 861 break; 862 } 863 if (signal_pending(current)) { 864 ret = -ERESTARTSYS; 865 break; 866 } 867 /* Nothing to read, let's sleep */ 868 schedule(); 869 } 870 if (!noblock) 871 finish_wait(sk_sleep(&q->sk), &wait); 872 873 put: 874 if (skb) { 875 ret = tap_put_user(q, skb, to); 876 if (unlikely(ret < 0)) 877 kfree_skb(skb); 878 else 879 consume_skb(skb); 880 } 881 return ret; 882 } 883 884 static ssize_t tap_read_iter(struct kiocb *iocb, struct iov_iter *to) 885 { 886 struct file *file = iocb->ki_filp; 887 struct tap_queue *q = file->private_data; 888 ssize_t len = iov_iter_count(to), ret; 889 890 ret = tap_do_read(q, to, file->f_flags & O_NONBLOCK, NULL); 891 ret = min_t(ssize_t, ret, len); 892 if (ret > 0) 893 iocb->ki_pos = ret; 894 return ret; 895 } 896 897 static struct tap_dev *tap_get_tap_dev(struct tap_queue *q) 898 { 899 struct tap_dev *tap; 900 901 ASSERT_RTNL(); 902 tap = rtnl_dereference(q->tap); 903 if (tap) 904 dev_hold(tap->dev); 905 906 return tap; 907 } 908 909 static void tap_put_tap_dev(struct tap_dev *tap) 910 { 911 dev_put(tap->dev); 912 } 913 914 static int tap_ioctl_set_queue(struct file *file, unsigned int flags) 915 { 916 struct tap_queue *q = file->private_data; 917 struct tap_dev *tap; 918 int ret; 919 920 tap = tap_get_tap_dev(q); 921 if (!tap) 922 return -EINVAL; 923 924 if (flags & IFF_ATTACH_QUEUE) 925 ret = tap_enable_queue(tap, file, q); 926 else if (flags & IFF_DETACH_QUEUE) 927 ret = tap_disable_queue(q); 928 else 929 ret = -EINVAL; 930 931 tap_put_tap_dev(tap); 932 return ret; 933 } 934 935 static int set_offload(struct tap_queue *q, unsigned long arg) 936 { 937 struct tap_dev *tap; 938 netdev_features_t features; 939 netdev_features_t feature_mask = 0; 940 941 tap = rtnl_dereference(q->tap); 942 if (!tap) 943 return -ENOLINK; 944 945 features = tap->dev->features; 946 947 if (arg & TUN_F_CSUM) { 948 feature_mask = NETIF_F_HW_CSUM; 949 950 if (arg & (TUN_F_TSO4 | TUN_F_TSO6)) { 951 if (arg & TUN_F_TSO_ECN) 952 feature_mask |= NETIF_F_TSO_ECN; 953 if (arg & TUN_F_TSO4) 954 feature_mask |= NETIF_F_TSO; 955 if (arg & TUN_F_TSO6) 956 feature_mask |= NETIF_F_TSO6; 957 } 958 } 959 960 /* tun/tap driver inverts the usage for TSO offloads, where 961 * setting the TSO bit means that the userspace wants to 962 * accept TSO frames and turning it off means that user space 963 * does not support TSO. 964 * For tap, we have to invert it to mean the same thing. 965 * When user space turns off TSO, we turn off GSO/LRO so that 966 * user-space will not receive TSO frames. 967 */ 968 if (feature_mask & (NETIF_F_TSO | NETIF_F_TSO6)) 969 features |= RX_OFFLOADS; 970 else 971 features &= ~RX_OFFLOADS; 972 973 /* tap_features are the same as features on tun/tap and 974 * reflect user expectations. 975 */ 976 tap->tap_features = feature_mask; 977 if (tap->update_features) 978 tap->update_features(tap, features); 979 980 return 0; 981 } 982 983 /* 984 * provide compatibility with generic tun/tap interface 985 */ 986 static long tap_ioctl(struct file *file, unsigned int cmd, 987 unsigned long arg) 988 { 989 struct tap_queue *q = file->private_data; 990 struct tap_dev *tap; 991 void __user *argp = (void __user *)arg; 992 struct ifreq __user *ifr = argp; 993 unsigned int __user *up = argp; 994 unsigned short u; 995 int __user *sp = argp; 996 struct sockaddr sa; 997 int s; 998 int ret; 999 1000 switch (cmd) { 1001 case TUNSETIFF: 1002 /* ignore the name, just look at flags */ 1003 if (get_user(u, &ifr->ifr_flags)) 1004 return -EFAULT; 1005 1006 ret = 0; 1007 if ((u & ~TAP_IFFEATURES) != (IFF_NO_PI | IFF_TAP)) 1008 ret = -EINVAL; 1009 else 1010 q->flags = (q->flags & ~TAP_IFFEATURES) | u; 1011 1012 return ret; 1013 1014 case TUNGETIFF: 1015 rtnl_lock(); 1016 tap = tap_get_tap_dev(q); 1017 if (!tap) { 1018 rtnl_unlock(); 1019 return -ENOLINK; 1020 } 1021 1022 ret = 0; 1023 u = q->flags; 1024 if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) || 1025 put_user(u, &ifr->ifr_flags)) 1026 ret = -EFAULT; 1027 tap_put_tap_dev(tap); 1028 rtnl_unlock(); 1029 return ret; 1030 1031 case TUNSETQUEUE: 1032 if (get_user(u, &ifr->ifr_flags)) 1033 return -EFAULT; 1034 rtnl_lock(); 1035 ret = tap_ioctl_set_queue(file, u); 1036 rtnl_unlock(); 1037 return ret; 1038 1039 case TUNGETFEATURES: 1040 if (put_user(IFF_TAP | IFF_NO_PI | TAP_IFFEATURES, up)) 1041 return -EFAULT; 1042 return 0; 1043 1044 case TUNSETSNDBUF: 1045 if (get_user(s, sp)) 1046 return -EFAULT; 1047 if (s <= 0) 1048 return -EINVAL; 1049 1050 q->sk.sk_sndbuf = s; 1051 return 0; 1052 1053 case TUNGETVNETHDRSZ: 1054 s = q->vnet_hdr_sz; 1055 if (put_user(s, sp)) 1056 return -EFAULT; 1057 return 0; 1058 1059 case TUNSETVNETHDRSZ: 1060 if (get_user(s, sp)) 1061 return -EFAULT; 1062 if (s < (int)sizeof(struct virtio_net_hdr)) 1063 return -EINVAL; 1064 1065 q->vnet_hdr_sz = s; 1066 return 0; 1067 1068 case TUNGETVNETLE: 1069 s = !!(q->flags & TAP_VNET_LE); 1070 if (put_user(s, sp)) 1071 return -EFAULT; 1072 return 0; 1073 1074 case TUNSETVNETLE: 1075 if (get_user(s, sp)) 1076 return -EFAULT; 1077 if (s) 1078 q->flags |= TAP_VNET_LE; 1079 else 1080 q->flags &= ~TAP_VNET_LE; 1081 return 0; 1082 1083 case TUNGETVNETBE: 1084 return tap_get_vnet_be(q, sp); 1085 1086 case TUNSETVNETBE: 1087 return tap_set_vnet_be(q, sp); 1088 1089 case TUNSETOFFLOAD: 1090 /* let the user check for future flags */ 1091 if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 | 1092 TUN_F_TSO_ECN | TUN_F_UFO)) 1093 return -EINVAL; 1094 1095 rtnl_lock(); 1096 ret = set_offload(q, arg); 1097 rtnl_unlock(); 1098 return ret; 1099 1100 case SIOCGIFHWADDR: 1101 rtnl_lock(); 1102 tap = tap_get_tap_dev(q); 1103 if (!tap) { 1104 rtnl_unlock(); 1105 return -ENOLINK; 1106 } 1107 ret = 0; 1108 dev_get_mac_address(&sa, dev_net(tap->dev), tap->dev->name); 1109 if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) || 1110 copy_to_user(&ifr->ifr_hwaddr, &sa, sizeof(sa))) 1111 ret = -EFAULT; 1112 tap_put_tap_dev(tap); 1113 rtnl_unlock(); 1114 return ret; 1115 1116 case SIOCSIFHWADDR: 1117 if (copy_from_user(&sa, &ifr->ifr_hwaddr, sizeof(sa))) 1118 return -EFAULT; 1119 rtnl_lock(); 1120 tap = tap_get_tap_dev(q); 1121 if (!tap) { 1122 rtnl_unlock(); 1123 return -ENOLINK; 1124 } 1125 ret = dev_set_mac_address_user(tap->dev, &sa, NULL); 1126 tap_put_tap_dev(tap); 1127 rtnl_unlock(); 1128 return ret; 1129 1130 default: 1131 return -EINVAL; 1132 } 1133 } 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 .compat_ioctl = compat_ptr_ioctl, 1145 }; 1146 1147 static int tap_get_user_xdp(struct tap_queue *q, struct xdp_buff *xdp) 1148 { 1149 struct tun_xdp_hdr *hdr = xdp->data_hard_start; 1150 struct virtio_net_hdr *gso = &hdr->gso; 1151 int buflen = hdr->buflen; 1152 int vnet_hdr_len = 0; 1153 struct tap_dev *tap; 1154 struct sk_buff *skb; 1155 int err, depth; 1156 1157 if (q->flags & IFF_VNET_HDR) 1158 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz); 1159 1160 skb = build_skb(xdp->data_hard_start, buflen); 1161 if (!skb) { 1162 err = -ENOMEM; 1163 goto err; 1164 } 1165 1166 skb_reserve(skb, xdp->data - xdp->data_hard_start); 1167 skb_put(skb, xdp->data_end - xdp->data); 1168 1169 skb_set_network_header(skb, ETH_HLEN); 1170 skb_reset_mac_header(skb); 1171 skb->protocol = eth_hdr(skb)->h_proto; 1172 1173 if (vnet_hdr_len) { 1174 err = virtio_net_hdr_to_skb(skb, gso, tap_is_little_endian(q)); 1175 if (err) 1176 goto err_kfree; 1177 } 1178 1179 /* Move network header to the right position for VLAN tagged packets */ 1180 if (eth_type_vlan(skb->protocol) && 1181 __vlan_get_protocol(skb, skb->protocol, &depth) != 0) 1182 skb_set_network_header(skb, depth); 1183 1184 rcu_read_lock(); 1185 tap = rcu_dereference(q->tap); 1186 if (tap) { 1187 skb->dev = tap->dev; 1188 skb_probe_transport_header(skb); 1189 dev_queue_xmit(skb); 1190 } else { 1191 kfree_skb(skb); 1192 } 1193 rcu_read_unlock(); 1194 1195 return 0; 1196 1197 err_kfree: 1198 kfree_skb(skb); 1199 err: 1200 rcu_read_lock(); 1201 tap = rcu_dereference(q->tap); 1202 if (tap && tap->count_tx_dropped) 1203 tap->count_tx_dropped(tap); 1204 rcu_read_unlock(); 1205 return err; 1206 } 1207 1208 static int tap_sendmsg(struct socket *sock, struct msghdr *m, 1209 size_t total_len) 1210 { 1211 struct tap_queue *q = container_of(sock, struct tap_queue, sock); 1212 struct tun_msg_ctl *ctl = m->msg_control; 1213 struct xdp_buff *xdp; 1214 int i; 1215 1216 if (m->msg_controllen == sizeof(struct tun_msg_ctl) && 1217 ctl && ctl->type == TUN_MSG_PTR) { 1218 for (i = 0; i < ctl->num; i++) { 1219 xdp = &((struct xdp_buff *)ctl->ptr)[i]; 1220 tap_get_user_xdp(q, xdp); 1221 } 1222 return 0; 1223 } 1224 1225 return tap_get_user(q, ctl ? ctl->ptr : NULL, &m->msg_iter, 1226 m->msg_flags & MSG_DONTWAIT); 1227 } 1228 1229 static int tap_recvmsg(struct socket *sock, struct msghdr *m, 1230 size_t total_len, int flags) 1231 { 1232 struct tap_queue *q = container_of(sock, struct tap_queue, sock); 1233 struct sk_buff *skb = m->msg_control; 1234 int ret; 1235 if (flags & ~(MSG_DONTWAIT|MSG_TRUNC)) { 1236 kfree_skb(skb); 1237 return -EINVAL; 1238 } 1239 ret = tap_do_read(q, &m->msg_iter, flags & MSG_DONTWAIT, skb); 1240 if (ret > total_len) { 1241 m->msg_flags |= MSG_TRUNC; 1242 ret = flags & MSG_TRUNC ? ret : total_len; 1243 } 1244 return ret; 1245 } 1246 1247 static int tap_peek_len(struct socket *sock) 1248 { 1249 struct tap_queue *q = container_of(sock, struct tap_queue, 1250 sock); 1251 return PTR_RING_PEEK_CALL(&q->ring, __skb_array_len_with_tag); 1252 } 1253 1254 /* Ops structure to mimic raw sockets with tun */ 1255 static const struct proto_ops tap_socket_ops = { 1256 .sendmsg = tap_sendmsg, 1257 .recvmsg = tap_recvmsg, 1258 .peek_len = tap_peek_len, 1259 }; 1260 1261 /* Get an underlying socket object from tun file. Returns error unless file is 1262 * attached to a device. The returned object works like a packet socket, it 1263 * can be used for sock_sendmsg/sock_recvmsg. The caller is responsible for 1264 * holding a reference to the file for as long as the socket is in use. */ 1265 struct socket *tap_get_socket(struct file *file) 1266 { 1267 struct tap_queue *q; 1268 if (file->f_op != &tap_fops) 1269 return ERR_PTR(-EINVAL); 1270 q = file->private_data; 1271 if (!q) 1272 return ERR_PTR(-EBADFD); 1273 return &q->sock; 1274 } 1275 EXPORT_SYMBOL_GPL(tap_get_socket); 1276 1277 struct ptr_ring *tap_get_ptr_ring(struct file *file) 1278 { 1279 struct tap_queue *q; 1280 1281 if (file->f_op != &tap_fops) 1282 return ERR_PTR(-EINVAL); 1283 q = file->private_data; 1284 if (!q) 1285 return ERR_PTR(-EBADFD); 1286 return &q->ring; 1287 } 1288 EXPORT_SYMBOL_GPL(tap_get_ptr_ring); 1289 1290 int tap_queue_resize(struct tap_dev *tap) 1291 { 1292 struct net_device *dev = tap->dev; 1293 struct tap_queue *q; 1294 struct ptr_ring **rings; 1295 int n = tap->numqueues; 1296 int ret, i = 0; 1297 1298 rings = kmalloc_array(n, sizeof(*rings), GFP_KERNEL); 1299 if (!rings) 1300 return -ENOMEM; 1301 1302 list_for_each_entry(q, &tap->queue_list, next) 1303 rings[i++] = &q->ring; 1304 1305 ret = ptr_ring_resize_multiple(rings, n, 1306 dev->tx_queue_len, GFP_KERNEL, 1307 __skb_array_destroy_skb); 1308 1309 kfree(rings); 1310 return ret; 1311 } 1312 EXPORT_SYMBOL_GPL(tap_queue_resize); 1313 1314 static int tap_list_add(dev_t major, const char *device_name) 1315 { 1316 struct major_info *tap_major; 1317 1318 tap_major = kzalloc(sizeof(*tap_major), GFP_ATOMIC); 1319 if (!tap_major) 1320 return -ENOMEM; 1321 1322 tap_major->major = MAJOR(major); 1323 1324 idr_init(&tap_major->minor_idr); 1325 spin_lock_init(&tap_major->minor_lock); 1326 1327 tap_major->device_name = device_name; 1328 1329 list_add_tail_rcu(&tap_major->next, &major_list); 1330 return 0; 1331 } 1332 1333 int tap_create_cdev(struct cdev *tap_cdev, dev_t *tap_major, 1334 const char *device_name, struct module *module) 1335 { 1336 int err; 1337 1338 err = alloc_chrdev_region(tap_major, 0, TAP_NUM_DEVS, device_name); 1339 if (err) 1340 goto out1; 1341 1342 cdev_init(tap_cdev, &tap_fops); 1343 tap_cdev->owner = module; 1344 err = cdev_add(tap_cdev, *tap_major, TAP_NUM_DEVS); 1345 if (err) 1346 goto out2; 1347 1348 err = tap_list_add(*tap_major, device_name); 1349 if (err) 1350 goto out3; 1351 1352 return 0; 1353 1354 out3: 1355 cdev_del(tap_cdev); 1356 out2: 1357 unregister_chrdev_region(*tap_major, TAP_NUM_DEVS); 1358 out1: 1359 return err; 1360 } 1361 EXPORT_SYMBOL_GPL(tap_create_cdev); 1362 1363 void tap_destroy_cdev(dev_t major, struct cdev *tap_cdev) 1364 { 1365 struct major_info *tap_major, *tmp; 1366 1367 cdev_del(tap_cdev); 1368 unregister_chrdev_region(major, TAP_NUM_DEVS); 1369 list_for_each_entry_safe(tap_major, tmp, &major_list, next) { 1370 if (tap_major->major == MAJOR(major)) { 1371 idr_destroy(&tap_major->minor_idr); 1372 list_del_rcu(&tap_major->next); 1373 kfree_rcu(tap_major, rcu); 1374 } 1375 } 1376 } 1377 EXPORT_SYMBOL_GPL(tap_destroy_cdev); 1378 1379 MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>"); 1380 MODULE_AUTHOR("Sainath Grandhi <sainath.grandhi@intel.com>"); 1381 MODULE_LICENSE("GPL"); 1382