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; 325 326 tap = tap_dev_get_rcu(dev); 327 if (!tap) 328 return RX_HANDLER_PASS; 329 330 q = tap_get_queue(tap, skb); 331 if (!q) 332 return RX_HANDLER_PASS; 333 334 skb_push(skb, ETH_HLEN); 335 336 /* Apply the forward feature mask so that we perform segmentation 337 * according to users wishes. This only works if VNET_HDR is 338 * enabled. 339 */ 340 if (q->flags & IFF_VNET_HDR) 341 features |= tap->tap_features; 342 if (netif_needs_gso(skb, features)) { 343 struct sk_buff *segs = __skb_gso_segment(skb, features, false); 344 345 if (IS_ERR(segs)) 346 goto drop; 347 348 if (!segs) { 349 if (ptr_ring_produce(&q->ring, skb)) 350 goto drop; 351 goto wake_up; 352 } 353 354 consume_skb(skb); 355 while (segs) { 356 struct sk_buff *nskb = segs->next; 357 358 segs->next = NULL; 359 if (ptr_ring_produce(&q->ring, segs)) { 360 kfree_skb(segs); 361 kfree_skb_list(nskb); 362 break; 363 } 364 segs = nskb; 365 } 366 } else { 367 /* If we receive a partial checksum and the tap side 368 * doesn't support checksum offload, compute the checksum. 369 * Note: it doesn't matter which checksum feature to 370 * check, we either support them all or none. 371 */ 372 if (skb->ip_summed == CHECKSUM_PARTIAL && 373 !(features & NETIF_F_CSUM_MASK) && 374 skb_checksum_help(skb)) 375 goto drop; 376 if (ptr_ring_produce(&q->ring, skb)) 377 goto drop; 378 } 379 380 wake_up: 381 wake_up_interruptible_poll(sk_sleep(&q->sk), EPOLLIN | EPOLLRDNORM | EPOLLRDBAND); 382 return RX_HANDLER_CONSUMED; 383 384 drop: 385 /* Count errors/drops only here, thus don't care about args. */ 386 if (tap->count_rx_dropped) 387 tap->count_rx_dropped(tap); 388 kfree_skb(skb); 389 return RX_HANDLER_CONSUMED; 390 } 391 EXPORT_SYMBOL_GPL(tap_handle_frame); 392 393 static struct major_info *tap_get_major(int major) 394 { 395 struct major_info *tap_major; 396 397 list_for_each_entry_rcu(tap_major, &major_list, next) { 398 if (tap_major->major == major) 399 return tap_major; 400 } 401 402 return NULL; 403 } 404 405 int tap_get_minor(dev_t major, struct tap_dev *tap) 406 { 407 int retval = -ENOMEM; 408 struct major_info *tap_major; 409 410 rcu_read_lock(); 411 tap_major = tap_get_major(MAJOR(major)); 412 if (!tap_major) { 413 retval = -EINVAL; 414 goto unlock; 415 } 416 417 spin_lock(&tap_major->minor_lock); 418 retval = idr_alloc(&tap_major->minor_idr, tap, 1, TAP_NUM_DEVS, GFP_ATOMIC); 419 if (retval >= 0) { 420 tap->minor = retval; 421 } else if (retval == -ENOSPC) { 422 netdev_err(tap->dev, "Too many tap devices\n"); 423 retval = -EINVAL; 424 } 425 spin_unlock(&tap_major->minor_lock); 426 427 unlock: 428 rcu_read_unlock(); 429 return retval < 0 ? retval : 0; 430 } 431 EXPORT_SYMBOL_GPL(tap_get_minor); 432 433 void tap_free_minor(dev_t major, struct tap_dev *tap) 434 { 435 struct major_info *tap_major; 436 437 rcu_read_lock(); 438 tap_major = tap_get_major(MAJOR(major)); 439 if (!tap_major) { 440 goto unlock; 441 } 442 443 spin_lock(&tap_major->minor_lock); 444 if (tap->minor) { 445 idr_remove(&tap_major->minor_idr, tap->minor); 446 tap->minor = 0; 447 } 448 spin_unlock(&tap_major->minor_lock); 449 450 unlock: 451 rcu_read_unlock(); 452 } 453 EXPORT_SYMBOL_GPL(tap_free_minor); 454 455 static struct tap_dev *dev_get_by_tap_file(int major, int minor) 456 { 457 struct net_device *dev = NULL; 458 struct tap_dev *tap; 459 struct major_info *tap_major; 460 461 rcu_read_lock(); 462 tap_major = tap_get_major(major); 463 if (!tap_major) { 464 tap = NULL; 465 goto unlock; 466 } 467 468 spin_lock(&tap_major->minor_lock); 469 tap = idr_find(&tap_major->minor_idr, minor); 470 if (tap) { 471 dev = tap->dev; 472 dev_hold(dev); 473 } 474 spin_unlock(&tap_major->minor_lock); 475 476 unlock: 477 rcu_read_unlock(); 478 return tap; 479 } 480 481 static void tap_sock_write_space(struct sock *sk) 482 { 483 wait_queue_head_t *wqueue; 484 485 if (!sock_writeable(sk) || 486 !test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags)) 487 return; 488 489 wqueue = sk_sleep(sk); 490 if (wqueue && waitqueue_active(wqueue)) 491 wake_up_interruptible_poll(wqueue, EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND); 492 } 493 494 static void tap_sock_destruct(struct sock *sk) 495 { 496 struct tap_queue *q = container_of(sk, struct tap_queue, sk); 497 498 ptr_ring_cleanup(&q->ring, __skb_array_destroy_skb); 499 } 500 501 static int tap_open(struct inode *inode, struct file *file) 502 { 503 struct net *net = current->nsproxy->net_ns; 504 struct tap_dev *tap; 505 struct tap_queue *q; 506 int err = -ENODEV; 507 508 rtnl_lock(); 509 tap = dev_get_by_tap_file(imajor(inode), iminor(inode)); 510 if (!tap) 511 goto err; 512 513 err = -ENOMEM; 514 q = (struct tap_queue *)sk_alloc(net, AF_UNSPEC, GFP_KERNEL, 515 &tap_proto, 0); 516 if (!q) 517 goto err; 518 if (ptr_ring_init(&q->ring, tap->dev->tx_queue_len, GFP_KERNEL)) { 519 sk_free(&q->sk); 520 goto err; 521 } 522 523 RCU_INIT_POINTER(q->sock.wq, &q->wq); 524 init_waitqueue_head(&q->wq.wait); 525 q->sock.type = SOCK_RAW; 526 q->sock.state = SS_CONNECTED; 527 q->sock.file = file; 528 q->sock.ops = &tap_socket_ops; 529 sock_init_data(&q->sock, &q->sk); 530 q->sk.sk_write_space = tap_sock_write_space; 531 q->sk.sk_destruct = tap_sock_destruct; 532 q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP; 533 q->vnet_hdr_sz = sizeof(struct virtio_net_hdr); 534 535 /* 536 * so far only KVM virtio_net uses tap, enable zero copy between 537 * guest kernel and host kernel when lower device supports zerocopy 538 * 539 * The macvlan supports zerocopy iff the lower device supports zero 540 * copy so we don't have to look at the lower device directly. 541 */ 542 if ((tap->dev->features & NETIF_F_HIGHDMA) && (tap->dev->features & NETIF_F_SG)) 543 sock_set_flag(&q->sk, SOCK_ZEROCOPY); 544 545 err = tap_set_queue(tap, file, q); 546 if (err) { 547 /* tap_sock_destruct() will take care of freeing ptr_ring */ 548 goto err_put; 549 } 550 551 dev_put(tap->dev); 552 553 rtnl_unlock(); 554 return err; 555 556 err_put: 557 sock_put(&q->sk); 558 err: 559 if (tap) 560 dev_put(tap->dev); 561 562 rtnl_unlock(); 563 return err; 564 } 565 566 static int tap_release(struct inode *inode, struct file *file) 567 { 568 struct tap_queue *q = file->private_data; 569 tap_put_queue(q); 570 return 0; 571 } 572 573 static __poll_t tap_poll(struct file *file, poll_table *wait) 574 { 575 struct tap_queue *q = file->private_data; 576 __poll_t mask = EPOLLERR; 577 578 if (!q) 579 goto out; 580 581 mask = 0; 582 poll_wait(file, &q->wq.wait, wait); 583 584 if (!ptr_ring_empty(&q->ring)) 585 mask |= EPOLLIN | EPOLLRDNORM; 586 587 if (sock_writeable(&q->sk) || 588 (!test_and_set_bit(SOCKWQ_ASYNC_NOSPACE, &q->sock.flags) && 589 sock_writeable(&q->sk))) 590 mask |= EPOLLOUT | EPOLLWRNORM; 591 592 out: 593 return mask; 594 } 595 596 static inline struct sk_buff *tap_alloc_skb(struct sock *sk, size_t prepad, 597 size_t len, size_t linear, 598 int noblock, int *err) 599 { 600 struct sk_buff *skb; 601 602 /* Under a page? Don't bother with paged skb. */ 603 if (prepad + len < PAGE_SIZE || !linear) 604 linear = len; 605 606 skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock, 607 err, 0); 608 if (!skb) 609 return NULL; 610 611 skb_reserve(skb, prepad); 612 skb_put(skb, linear); 613 skb->data_len = len - linear; 614 skb->len += len - linear; 615 616 return skb; 617 } 618 619 /* Neighbour code has some assumptions on HH_DATA_MOD alignment */ 620 #define TAP_RESERVE HH_DATA_OFF(ETH_HLEN) 621 622 /* Get packet from user space buffer */ 623 static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, 624 struct iov_iter *from, int noblock) 625 { 626 int good_linear = SKB_MAX_HEAD(TAP_RESERVE); 627 struct sk_buff *skb; 628 struct tap_dev *tap; 629 unsigned long total_len = iov_iter_count(from); 630 unsigned long len = total_len; 631 int err; 632 struct virtio_net_hdr vnet_hdr = { 0 }; 633 int vnet_hdr_len = 0; 634 int copylen = 0; 635 int depth; 636 bool zerocopy = false; 637 size_t linear; 638 639 if (q->flags & IFF_VNET_HDR) { 640 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz); 641 642 err = -EINVAL; 643 if (len < vnet_hdr_len) 644 goto err; 645 len -= vnet_hdr_len; 646 647 err = -EFAULT; 648 if (!copy_from_iter_full(&vnet_hdr, sizeof(vnet_hdr), from)) 649 goto err; 650 iov_iter_advance(from, vnet_hdr_len - sizeof(vnet_hdr)); 651 if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) && 652 tap16_to_cpu(q, vnet_hdr.csum_start) + 653 tap16_to_cpu(q, vnet_hdr.csum_offset) + 2 > 654 tap16_to_cpu(q, vnet_hdr.hdr_len)) 655 vnet_hdr.hdr_len = cpu_to_tap16(q, 656 tap16_to_cpu(q, vnet_hdr.csum_start) + 657 tap16_to_cpu(q, vnet_hdr.csum_offset) + 2); 658 err = -EINVAL; 659 if (tap16_to_cpu(q, vnet_hdr.hdr_len) > len) 660 goto err; 661 } 662 663 err = -EINVAL; 664 if (unlikely(len < ETH_HLEN)) 665 goto err; 666 667 if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) { 668 struct iov_iter i; 669 670 copylen = vnet_hdr.hdr_len ? 671 tap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN; 672 if (copylen > good_linear) 673 copylen = good_linear; 674 else if (copylen < ETH_HLEN) 675 copylen = ETH_HLEN; 676 linear = copylen; 677 i = *from; 678 iov_iter_advance(&i, copylen); 679 if (iov_iter_npages(&i, INT_MAX) <= MAX_SKB_FRAGS) 680 zerocopy = true; 681 } 682 683 if (!zerocopy) { 684 copylen = len; 685 linear = tap16_to_cpu(q, vnet_hdr.hdr_len); 686 if (linear > good_linear) 687 linear = good_linear; 688 else if (linear < ETH_HLEN) 689 linear = ETH_HLEN; 690 } 691 692 skb = tap_alloc_skb(&q->sk, TAP_RESERVE, copylen, 693 linear, noblock, &err); 694 if (!skb) 695 goto err; 696 697 if (zerocopy) 698 err = zerocopy_sg_from_iter(skb, from); 699 else 700 err = skb_copy_datagram_from_iter(skb, 0, from, len); 701 702 if (err) 703 goto err_kfree; 704 705 skb_set_network_header(skb, ETH_HLEN); 706 skb_reset_mac_header(skb); 707 skb->protocol = eth_hdr(skb)->h_proto; 708 709 if (vnet_hdr_len) { 710 err = virtio_net_hdr_to_skb(skb, &vnet_hdr, 711 tap_is_little_endian(q)); 712 if (err) 713 goto err_kfree; 714 } 715 716 skb_probe_transport_header(skb); 717 718 /* Move network header to the right position for VLAN tagged packets */ 719 if ((skb->protocol == htons(ETH_P_8021Q) || 720 skb->protocol == htons(ETH_P_8021AD)) && 721 __vlan_get_protocol(skb, skb->protocol, &depth) != 0) 722 skb_set_network_header(skb, depth); 723 724 rcu_read_lock(); 725 tap = rcu_dereference(q->tap); 726 /* copy skb_ubuf_info for callback when skb has no error */ 727 if (zerocopy) { 728 skb_shinfo(skb)->destructor_arg = msg_control; 729 skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY; 730 skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG; 731 } else if (msg_control) { 732 struct ubuf_info *uarg = msg_control; 733 uarg->callback(uarg, false); 734 } 735 736 if (tap) { 737 skb->dev = tap->dev; 738 dev_queue_xmit(skb); 739 } else { 740 kfree_skb(skb); 741 } 742 rcu_read_unlock(); 743 744 return total_len; 745 746 err_kfree: 747 kfree_skb(skb); 748 749 err: 750 rcu_read_lock(); 751 tap = rcu_dereference(q->tap); 752 if (tap && tap->count_tx_dropped) 753 tap->count_tx_dropped(tap); 754 rcu_read_unlock(); 755 756 return err; 757 } 758 759 static ssize_t tap_write_iter(struct kiocb *iocb, struct iov_iter *from) 760 { 761 struct file *file = iocb->ki_filp; 762 struct tap_queue *q = file->private_data; 763 764 return tap_get_user(q, NULL, from, file->f_flags & O_NONBLOCK); 765 } 766 767 /* Put packet to the user space buffer */ 768 static ssize_t tap_put_user(struct tap_queue *q, 769 const struct sk_buff *skb, 770 struct iov_iter *iter) 771 { 772 int ret; 773 int vnet_hdr_len = 0; 774 int vlan_offset = 0; 775 int total; 776 777 if (q->flags & IFF_VNET_HDR) { 778 int vlan_hlen = skb_vlan_tag_present(skb) ? VLAN_HLEN : 0; 779 struct virtio_net_hdr vnet_hdr; 780 781 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 vlan_hlen)) 788 BUG(); 789 790 if (copy_to_iter(&vnet_hdr, sizeof(vnet_hdr), iter) != 791 sizeof(vnet_hdr)) 792 return -EFAULT; 793 794 iov_iter_advance(iter, vnet_hdr_len - sizeof(vnet_hdr)); 795 } 796 total = vnet_hdr_len; 797 total += skb->len; 798 799 if (skb_vlan_tag_present(skb)) { 800 struct { 801 __be16 h_vlan_proto; 802 __be16 h_vlan_TCI; 803 } veth; 804 veth.h_vlan_proto = skb->vlan_proto; 805 veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb)); 806 807 vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto); 808 total += VLAN_HLEN; 809 810 ret = skb_copy_datagram_iter(skb, 0, iter, vlan_offset); 811 if (ret || !iov_iter_count(iter)) 812 goto done; 813 814 ret = copy_to_iter(&veth, sizeof(veth), iter); 815 if (ret != sizeof(veth) || !iov_iter_count(iter)) 816 goto done; 817 } 818 819 ret = skb_copy_datagram_iter(skb, vlan_offset, iter, 820 skb->len - vlan_offset); 821 822 done: 823 return ret ? ret : total; 824 } 825 826 static ssize_t tap_do_read(struct tap_queue *q, 827 struct iov_iter *to, 828 int noblock, struct sk_buff *skb) 829 { 830 DEFINE_WAIT(wait); 831 ssize_t ret = 0; 832 833 if (!iov_iter_count(to)) { 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 = ptr_ring_consume(&q->ring); 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, NULL); 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_get_user_xdp(struct tap_queue *q, struct xdp_buff *xdp) 1150 { 1151 struct tun_xdp_hdr *hdr = xdp->data_hard_start; 1152 struct virtio_net_hdr *gso = &hdr->gso; 1153 int buflen = hdr->buflen; 1154 int vnet_hdr_len = 0; 1155 struct tap_dev *tap; 1156 struct sk_buff *skb; 1157 int err, depth; 1158 1159 if (q->flags & IFF_VNET_HDR) 1160 vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz); 1161 1162 skb = build_skb(xdp->data_hard_start, buflen); 1163 if (!skb) { 1164 err = -ENOMEM; 1165 goto err; 1166 } 1167 1168 skb_reserve(skb, xdp->data - xdp->data_hard_start); 1169 skb_put(skb, xdp->data_end - xdp->data); 1170 1171 skb_set_network_header(skb, ETH_HLEN); 1172 skb_reset_mac_header(skb); 1173 skb->protocol = eth_hdr(skb)->h_proto; 1174 1175 if (vnet_hdr_len) { 1176 err = virtio_net_hdr_to_skb(skb, gso, tap_is_little_endian(q)); 1177 if (err) 1178 goto err_kfree; 1179 } 1180 1181 /* Move network header to the right position for VLAN tagged packets */ 1182 if ((skb->protocol == htons(ETH_P_8021Q) || 1183 skb->protocol == htons(ETH_P_8021AD)) && 1184 __vlan_get_protocol(skb, skb->protocol, &depth) != 0) 1185 skb_set_network_header(skb, depth); 1186 1187 rcu_read_lock(); 1188 tap = rcu_dereference(q->tap); 1189 if (tap) { 1190 skb->dev = tap->dev; 1191 skb_probe_transport_header(skb); 1192 dev_queue_xmit(skb); 1193 } else { 1194 kfree_skb(skb); 1195 } 1196 rcu_read_unlock(); 1197 1198 return 0; 1199 1200 err_kfree: 1201 kfree_skb(skb); 1202 err: 1203 rcu_read_lock(); 1204 tap = rcu_dereference(q->tap); 1205 if (tap && tap->count_tx_dropped) 1206 tap->count_tx_dropped(tap); 1207 rcu_read_unlock(); 1208 return err; 1209 } 1210 1211 static int tap_sendmsg(struct socket *sock, struct msghdr *m, 1212 size_t total_len) 1213 { 1214 struct tap_queue *q = container_of(sock, struct tap_queue, sock); 1215 struct tun_msg_ctl *ctl = m->msg_control; 1216 struct xdp_buff *xdp; 1217 int i; 1218 1219 if (ctl && (ctl->type == TUN_MSG_PTR)) { 1220 for (i = 0; i < ctl->num; i++) { 1221 xdp = &((struct xdp_buff *)ctl->ptr)[i]; 1222 tap_get_user_xdp(q, xdp); 1223 } 1224 return 0; 1225 } 1226 1227 return tap_get_user(q, ctl ? ctl->ptr : NULL, &m->msg_iter, 1228 m->msg_flags & MSG_DONTWAIT); 1229 } 1230 1231 static int tap_recvmsg(struct socket *sock, struct msghdr *m, 1232 size_t total_len, int flags) 1233 { 1234 struct tap_queue *q = container_of(sock, struct tap_queue, sock); 1235 struct sk_buff *skb = m->msg_control; 1236 int ret; 1237 if (flags & ~(MSG_DONTWAIT|MSG_TRUNC)) { 1238 kfree_skb(skb); 1239 return -EINVAL; 1240 } 1241 ret = tap_do_read(q, &m->msg_iter, flags & MSG_DONTWAIT, skb); 1242 if (ret > total_len) { 1243 m->msg_flags |= MSG_TRUNC; 1244 ret = flags & MSG_TRUNC ? ret : total_len; 1245 } 1246 return ret; 1247 } 1248 1249 static int tap_peek_len(struct socket *sock) 1250 { 1251 struct tap_queue *q = container_of(sock, struct tap_queue, 1252 sock); 1253 return PTR_RING_PEEK_CALL(&q->ring, __skb_array_len_with_tag); 1254 } 1255 1256 /* Ops structure to mimic raw sockets with tun */ 1257 static const struct proto_ops tap_socket_ops = { 1258 .sendmsg = tap_sendmsg, 1259 .recvmsg = tap_recvmsg, 1260 .peek_len = tap_peek_len, 1261 }; 1262 1263 /* Get an underlying socket object from tun file. Returns error unless file is 1264 * attached to a device. The returned object works like a packet socket, it 1265 * can be used for sock_sendmsg/sock_recvmsg. The caller is responsible for 1266 * holding a reference to the file for as long as the socket is in use. */ 1267 struct socket *tap_get_socket(struct file *file) 1268 { 1269 struct tap_queue *q; 1270 if (file->f_op != &tap_fops) 1271 return ERR_PTR(-EINVAL); 1272 q = file->private_data; 1273 if (!q) 1274 return ERR_PTR(-EBADFD); 1275 return &q->sock; 1276 } 1277 EXPORT_SYMBOL_GPL(tap_get_socket); 1278 1279 struct ptr_ring *tap_get_ptr_ring(struct file *file) 1280 { 1281 struct tap_queue *q; 1282 1283 if (file->f_op != &tap_fops) 1284 return ERR_PTR(-EINVAL); 1285 q = file->private_data; 1286 if (!q) 1287 return ERR_PTR(-EBADFD); 1288 return &q->ring; 1289 } 1290 EXPORT_SYMBOL_GPL(tap_get_ptr_ring); 1291 1292 int tap_queue_resize(struct tap_dev *tap) 1293 { 1294 struct net_device *dev = tap->dev; 1295 struct tap_queue *q; 1296 struct ptr_ring **rings; 1297 int n = tap->numqueues; 1298 int ret, i = 0; 1299 1300 rings = kmalloc_array(n, sizeof(*rings), GFP_KERNEL); 1301 if (!rings) 1302 return -ENOMEM; 1303 1304 list_for_each_entry(q, &tap->queue_list, next) 1305 rings[i++] = &q->ring; 1306 1307 ret = ptr_ring_resize_multiple(rings, n, 1308 dev->tx_queue_len, GFP_KERNEL, 1309 __skb_array_destroy_skb); 1310 1311 kfree(rings); 1312 return ret; 1313 } 1314 EXPORT_SYMBOL_GPL(tap_queue_resize); 1315 1316 static int tap_list_add(dev_t major, const char *device_name) 1317 { 1318 struct major_info *tap_major; 1319 1320 tap_major = kzalloc(sizeof(*tap_major), GFP_ATOMIC); 1321 if (!tap_major) 1322 return -ENOMEM; 1323 1324 tap_major->major = MAJOR(major); 1325 1326 idr_init(&tap_major->minor_idr); 1327 spin_lock_init(&tap_major->minor_lock); 1328 1329 tap_major->device_name = device_name; 1330 1331 list_add_tail_rcu(&tap_major->next, &major_list); 1332 return 0; 1333 } 1334 1335 int tap_create_cdev(struct cdev *tap_cdev, dev_t *tap_major, 1336 const char *device_name, struct module *module) 1337 { 1338 int err; 1339 1340 err = alloc_chrdev_region(tap_major, 0, TAP_NUM_DEVS, device_name); 1341 if (err) 1342 goto out1; 1343 1344 cdev_init(tap_cdev, &tap_fops); 1345 tap_cdev->owner = module; 1346 err = cdev_add(tap_cdev, *tap_major, TAP_NUM_DEVS); 1347 if (err) 1348 goto out2; 1349 1350 err = tap_list_add(*tap_major, device_name); 1351 if (err) 1352 goto out3; 1353 1354 return 0; 1355 1356 out3: 1357 cdev_del(tap_cdev); 1358 out2: 1359 unregister_chrdev_region(*tap_major, TAP_NUM_DEVS); 1360 out1: 1361 return err; 1362 } 1363 EXPORT_SYMBOL_GPL(tap_create_cdev); 1364 1365 void tap_destroy_cdev(dev_t major, struct cdev *tap_cdev) 1366 { 1367 struct major_info *tap_major, *tmp; 1368 1369 cdev_del(tap_cdev); 1370 unregister_chrdev_region(major, TAP_NUM_DEVS); 1371 list_for_each_entry_safe(tap_major, tmp, &major_list, next) { 1372 if (tap_major->major == MAJOR(major)) { 1373 idr_destroy(&tap_major->minor_idr); 1374 list_del_rcu(&tap_major->next); 1375 kfree_rcu(tap_major, rcu); 1376 } 1377 } 1378 } 1379 EXPORT_SYMBOL_GPL(tap_destroy_cdev); 1380 1381 MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>"); 1382 MODULE_AUTHOR("Sainath Grandhi <sainath.grandhi@intel.com>"); 1383 MODULE_LICENSE("GPL"); 1384