drivers/net/macvtap.c

   1 #include <linux/etherdevice.h>
   2 #include <linux/if_macvlan.h>
   3 #include <linux/interrupt.h>
   4 #include <linux/nsproxy.h>
   5 #include <linux/compat.h>
   6 #include <linux/if_tun.h>
   7 #include <linux/module.h>
   8 #include <linux/skbuff.h>
   9 #include <linux/cache.h>
  10 #include <linux/sched.h>
  11 #include <linux/types.h>
  12 #include <linux/slab.h>
  13 #include <linux/init.h>
  14 #include <linux/wait.h>
  15 #include <linux/cdev.h>
  16 #include <linux/fs.h>
  17
  18 #include <net/net_namespace.h>
  19 #include <net/rtnetlink.h>
  20 #include <net/sock.h>
  21 #include <linux/virtio_net.h>
  22
  23 /*
  24  * A macvtap queue is the central object of this driver, it connects
  25  * an open character device to a macvlan interface. There can be
  26  * multiple queues on one interface, which map back to queues
  27  * implemented in hardware on the underlying device.
  28  *
  29  * macvtap_proto is used to allocate queues through the sock allocation
  30  * mechanism.
  31  *
  32  * TODO: multiqueue support is currently not implemented, even though
  33  * macvtap is basically prepared for that. We will need to add this
  34  * here as well as in virtio-net and qemu to get line rate on 10gbit
  35  * adapters from a guest.
  36  */
  37 struct macvtap_queue {
  38         struct sock sk;
  39         struct socket sock;
  40         struct socket_wq wq;
  41         int vnet_hdr_sz;
  42         struct macvlan_dev *vlan;
  43         struct file *file;
  44         unsigned int flags;
  45 };
  46
  47 static struct proto macvtap_proto = {
  48         .name = "macvtap",
  49         .owner = THIS_MODULE,
  50         .obj_size = sizeof (struct macvtap_queue),
  51 };
  52
  53 /*
  54  * Minor number matches netdev->ifindex, so need a potentially
  55  * large value. This also makes it possible to split the
  56  * tap functionality out again in the future by offering it
  57  * from other drivers besides macvtap. As long as every device
  58  * only has one tap, the interface numbers assure that the
  59  * device nodes are unique.
  60  */
  61 static dev_t macvtap_major;
  62 #define MACVTAP_NUM_DEVS 65536
  63 static struct class *macvtap_class;
  64 static struct cdev macvtap_cdev;
  65
  66 static const struct proto_ops macvtap_socket_ops;
  67
  68 /*
  69  * RCU usage:
  70  * The macvtap_queue and the macvlan_dev are loosely coupled, the
  71  * pointers from one to the other can only be read while rcu_read_lock
  72  * or macvtap_lock is held.
  73  *
  74  * Both the file and the macvlan_dev hold a reference on the macvtap_queue
  75  * through sock_hold(&q->sk). When the macvlan_dev goes away first,
  76  * q->vlan becomes inaccessible. When the files gets closed,
  77  * macvtap_get_queue() fails.
  78  *
  79  * There may still be references to the struct sock inside of the
  80  * queue from outbound SKBs, but these never reference back to the
  81  * file or the dev. The data structure is freed through __sk_free
  82  * when both our references and any pending SKBs are gone.
  83  */
  84 static DEFINE_SPINLOCK(macvtap_lock);
  85
  86 /*
  87  * get_slot: return a [unused/occupied] slot in vlan->taps[]:
  88  *      - if 'q' is NULL, return the first empty slot;
  89  *      - otherwise, return the slot this pointer occupies.
  90  */
  91 static int get_slot(struct macvlan_dev *vlan, struct macvtap_queue *q)
  92 {
  93         int i;
  94
  95         for (i = 0; i < MAX_MACVTAP_QUEUES; i++) {
  96                 if (rcu_dereference(vlan->taps[i]) == q)
  97                         return i;
  98         }
  99
 100         /* Should never happen */
 101         BUG_ON(1);
 102 }
 103
 104 static int macvtap_set_queue(struct net_device *dev, struct file *file,
 105                                 struct macvtap_queue *q)
 106 {
 107         struct macvlan_dev *vlan = netdev_priv(dev);
 108         int index;
 109         int err = -EBUSY;
 110
 111         spin_lock(&macvtap_lock);
 112         if (vlan->numvtaps == MAX_MACVTAP_QUEUES)
 113                 goto out;
 114
 115         err = 0;
 116         index = get_slot(vlan, NULL);
 117         rcu_assign_pointer(q->vlan, vlan);
 118         rcu_assign_pointer(vlan->taps[index], q);
 119         sock_hold(&q->sk);
 120
 121         q->file = file;
 122         file->private_data = q;
 123
 124         vlan->numvtaps++;
 125
 126 out:
 127         spin_unlock(&macvtap_lock);
 128         return err;
 129 }
 130
 131 /*
 132  * The file owning the queue got closed, give up both
 133  * the reference that the files holds as well as the
 134  * one from the macvlan_dev if that still exists.
 135  *
 136  * Using the spinlock makes sure that we don't get
 137  * to the queue again after destroying it.
 138  */
 139 static void macvtap_put_queue(struct macvtap_queue *q)
 140 {
 141         struct macvlan_dev *vlan;
 142
 143         spin_lock(&macvtap_lock);
 144         vlan = rcu_dereference(q->vlan);
 145         if (vlan) {
 146                 int index = get_slot(vlan, q);
 147
 148                 rcu_assign_pointer(vlan->taps[index], NULL);
 149                 rcu_assign_pointer(q->vlan, NULL);
 150                 sock_put(&q->sk);
 151                 --vlan->numvtaps;
 152         }
 153
 154         spin_unlock(&macvtap_lock);
 155
 156         synchronize_rcu();
 157         sock_put(&q->sk);
 158 }
 159
 160 /*
 161  * Select a queue based on the rxq of the device on which this packet
 162  * arrived. If the incoming device is not mq, calculate a flow hash
 163  * to select a queue. If all fails, find the first available queue.
 164  * Cache vlan->numvtaps since it can become zero during the execution
 165  * of this function.
 166  */
 167 static struct macvtap_queue *macvtap_get_queue(struct net_device *dev,
 168                                                struct sk_buff *skb)
 169 {
 170         struct macvlan_dev *vlan = netdev_priv(dev);
 171         struct macvtap_queue *tap = NULL;
 172         int numvtaps = vlan->numvtaps;
 173         __u32 rxq;
 174
 175         if (!numvtaps)
 176                 goto out;
 177
 178         if (likely(skb_rx_queue_recorded(skb))) {
 179                 rxq = skb_get_rx_queue(skb);
 180
 181                 while (unlikely(rxq >= numvtaps))
 182                         rxq -= numvtaps;
 183
 184                 tap = rcu_dereference(vlan->taps[rxq]);
 185                 if (tap)
 186                         goto out;
 187         }
 188
 189         /* Check if we can use flow to select a queue */
 190         rxq = skb_get_rxhash(skb);
 191         if (rxq) {
 192                 tap = rcu_dereference(vlan->taps[rxq % numvtaps]);
 193                 if (tap)
 194                         goto out;
 195         }
 196
 197         /* Everything failed - find first available queue */
 198         for (rxq = 0; rxq < MAX_MACVTAP_QUEUES; rxq++) {
 199                 tap = rcu_dereference(vlan->taps[rxq]);
 200                 if (tap)
 201                         break;
 202         }
 203
 204 out:
 205         return tap;
 206 }
 207
 208 /*
 209  * The net_device is going away, give up the reference
 210  * that it holds on all queues and safely set the pointer
 211  * from the queues to NULL.
 212  */
 213 static void macvtap_del_queues(struct net_device *dev)
 214 {
 215         struct macvlan_dev *vlan = netdev_priv(dev);
 216         struct macvtap_queue *q, *qlist[MAX_MACVTAP_QUEUES];
 217         int i, j = 0;
 218
 219         /* macvtap_put_queue can free some slots, so go through all slots */
 220         spin_lock(&macvtap_lock);
 221         for (i = 0; i < MAX_MACVTAP_QUEUES && vlan->numvtaps; i++) {
 222                 q = rcu_dereference(vlan->taps[i]);
 223                 if (q) {
 224                         qlist[j++] = q;
 225                         rcu_assign_pointer(vlan->taps[i], NULL);
 226                         rcu_assign_pointer(q->vlan, NULL);
 227                         vlan->numvtaps--;
 228                 }
 229         }
 230         BUG_ON(vlan->numvtaps != 0);
 231         spin_unlock(&macvtap_lock);
 232
 233         synchronize_rcu();
 234
 235         for (--j; j >= 0; j--)
 236                 sock_put(&qlist[j]->sk);
 237 }
 238
 239 /*
 240  * Forward happens for data that gets sent from one macvlan
 241  * endpoint to another one in bridge mode. We just take
 242  * the skb and put it into the receive queue.
 243  */
 244 static int macvtap_forward(struct net_device *dev, struct sk_buff *skb)
 245 {
 246         struct macvtap_queue *q = macvtap_get_queue(dev, skb);
 247         if (!q)
 248                 goto drop;
 249
 250         if (skb_queue_len(&q->sk.sk_receive_queue) >= dev->tx_queue_len)
 251                 goto drop;
 252
 253         skb_queue_tail(&q->sk.sk_receive_queue, skb);
 254         wake_up_interruptible_poll(sk_sleep(&q->sk), POLLIN | POLLRDNORM | POLLRDBAND);
 255         return NET_RX_SUCCESS;
 256
 257 drop:
 258         kfree_skb(skb);
 259         return NET_RX_DROP;
 260 }
 261
 262 /*
 263  * Receive is for data from the external interface (lowerdev),
 264  * in case of macvtap, we can treat that the same way as
 265  * forward, which macvlan cannot.
 266  */
 267 static int macvtap_receive(struct sk_buff *skb)
 268 {
 269         skb_push(skb, ETH_HLEN);
 270         return macvtap_forward(skb->dev, skb);
 271 }
 272
 273 static int macvtap_newlink(struct net *src_net,
 274                            struct net_device *dev,
 275                            struct nlattr *tb[],
 276                            struct nlattr *data[])
 277 {
 278         struct device *classdev;
 279         dev_t devt;
 280         int err;
 281
 282         err = macvlan_common_newlink(src_net, dev, tb, data,
 283                                      macvtap_receive, macvtap_forward);
 284         if (err)
 285                 goto out;
 286
 287         devt = MKDEV(MAJOR(macvtap_major), dev->ifindex);
 288
 289         classdev = device_create(macvtap_class, &dev->dev, devt,
 290                                  dev, "tap%d", dev->ifindex);
 291         if (IS_ERR(classdev)) {
 292                 err = PTR_ERR(classdev);
 293                 macvtap_del_queues(dev);
 294         }
 295
 296 out:
 297         return err;
 298 }
 299
 300 static void macvtap_dellink(struct net_device *dev,
 301                             struct list_head *head)
 302 {
 303         device_destroy(macvtap_class,
 304                        MKDEV(MAJOR(macvtap_major), dev->ifindex));
 305
 306         macvtap_del_queues(dev);
 307         macvlan_dellink(dev, head);
 308 }
 309
 310 static void macvtap_setup(struct net_device *dev)
 311 {
 312         macvlan_common_setup(dev);
 313         dev->tx_queue_len = TUN_READQ_SIZE;
 314 }
 315
 316 static struct rtnl_link_ops macvtap_link_ops __read_mostly = {
 317         .kind           = "macvtap",
 318         .setup          = macvtap_setup,
 319         .newlink        = macvtap_newlink,
 320         .dellink        = macvtap_dellink,
 321 };
 322
 323
 324 static void macvtap_sock_write_space(struct sock *sk)
 325 {
 326         wait_queue_head_t *wqueue;
 327
 328         if (!sock_writeable(sk) ||
 329             !test_and_clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags))
 330                 return;
 331
 332         wqueue = sk_sleep(sk);
 333         if (wqueue && waitqueue_active(wqueue))
 334                 wake_up_interruptible_poll(wqueue, POLLOUT | POLLWRNORM | POLLWRBAND);
 335 }
 336
 337 static int macvtap_open(struct inode *inode, struct file *file)
 338 {
 339         struct net *net = current->nsproxy->net_ns;
 340         struct net_device *dev = dev_get_by_index(net, iminor(inode));
 341         struct macvtap_queue *q;
 342         int err;
 343
 344         err = -ENODEV;
 345         if (!dev)
 346                 goto out;
 347
 348         /* check if this is a macvtap device */
 349         err = -EINVAL;
 350         if (dev->rtnl_link_ops != &macvtap_link_ops)
 351                 goto out;
 352
 353         err = -ENOMEM;
 354         q = (struct macvtap_queue *)sk_alloc(net, AF_UNSPEC, GFP_KERNEL,
 355                                              &macvtap_proto);
 356         if (!q)
 357                 goto out;
 358
 359         q->sock.wq = &q->wq;
 360         init_waitqueue_head(&q->wq.wait);
 361         q->sock.type = SOCK_RAW;
 362         q->sock.state = SS_CONNECTED;
 363         q->sock.file = file;
 364         q->sock.ops = &macvtap_socket_ops;
 365         sock_init_data(&q->sock, &q->sk);
 366         q->sk.sk_write_space = macvtap_sock_write_space;
 367         q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP;
 368         q->vnet_hdr_sz = sizeof(struct virtio_net_hdr);
 369
 370         err = macvtap_set_queue(dev, file, q);
 371         if (err)
 372                 sock_put(&q->sk);
 373
 374 out:
 375         if (dev)
 376                 dev_put(dev);
 377
 378         return err;
 379 }
 380
 381 static int macvtap_release(struct inode *inode, struct file *file)
 382 {
 383         struct macvtap_queue *q = file->private_data;
 384         macvtap_put_queue(q);
 385         return 0;
 386 }
 387
 388 static unsigned int macvtap_poll(struct file *file, poll_table * wait)
 389 {
 390         struct macvtap_queue *q = file->private_data;
 391         unsigned int mask = POLLERR;
 392
 393         if (!q)
 394                 goto out;
 395
 396         mask = 0;
 397         poll_wait(file, &q->wq.wait, wait);
 398
 399         if (!skb_queue_empty(&q->sk.sk_receive_queue))
 400                 mask |= POLLIN | POLLRDNORM;
 401
 402         if (sock_writeable(&q->sk) ||
 403             (!test_and_set_bit(SOCK_ASYNC_NOSPACE, &q->sock.flags) &&
 404              sock_writeable(&q->sk)))
 405                 mask |= POLLOUT | POLLWRNORM;
 406
 407 out:
 408         return mask;
 409 }
 410
 411 static inline struct sk_buff *macvtap_alloc_skb(struct sock *sk, size_t prepad,
 412                                                 size_t len, size_t linear,
 413                                                 int noblock, int *err)
 414 {
 415         struct sk_buff *skb;
 416
 417         /* Under a page?  Don't bother with paged skb. */
 418         if (prepad + len < PAGE_SIZE || !linear)
 419                 linear = len;
 420
 421         skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
 422                                    err);
 423         if (!skb)
 424                 return NULL;
 425
 426         skb_reserve(skb, prepad);
 427         skb_put(skb, linear);
 428         skb->data_len = len - linear;
 429         skb->len += len - linear;
 430
 431         return skb;
 432 }
 433
 434 /*
 435  * macvtap_skb_from_vnet_hdr and macvtap_skb_to_vnet_hdr should
 436  * be shared with the tun/tap driver.
 437  */
 438 static int macvtap_skb_from_vnet_hdr(struct sk_buff *skb,
 439                                      struct virtio_net_hdr *vnet_hdr)
 440 {
 441         unsigned short gso_type = 0;
 442         if (vnet_hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
 443                 switch (vnet_hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
 444                 case VIRTIO_NET_HDR_GSO_TCPV4:
 445                         gso_type = SKB_GSO_TCPV4;
 446                         break;
 447                 case VIRTIO_NET_HDR_GSO_TCPV6:
 448                         gso_type = SKB_GSO_TCPV6;
 449                         break;
 450                 case VIRTIO_NET_HDR_GSO_UDP:
 451                         gso_type = SKB_GSO_UDP;
 452                         break;
 453                 default:
 454                         return -EINVAL;
 455                 }
 456
 457                 if (vnet_hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
 458                         gso_type |= SKB_GSO_TCP_ECN;
 459
 460                 if (vnet_hdr->gso_size == 0)
 461                         return -EINVAL;
 462         }
 463
 464         if (vnet_hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
 465                 if (!skb_partial_csum_set(skb, vnet_hdr->csum_start,
 466                                           vnet_hdr->csum_offset))
 467                         return -EINVAL;
 468         }
 469
 470         if (vnet_hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
 471                 skb_shinfo(skb)->gso_size = vnet_hdr->gso_size;
 472                 skb_shinfo(skb)->gso_type = gso_type;
 473
 474                 /* Header must be checked, and gso_segs computed. */
 475                 skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
 476                 skb_shinfo(skb)->gso_segs = 0;
 477         }
 478         return 0;
 479 }
 480
 481 static int macvtap_skb_to_vnet_hdr(const struct sk_buff *skb,
 482                                    struct virtio_net_hdr *vnet_hdr)
 483 {
 484         memset(vnet_hdr, 0, sizeof(*vnet_hdr));
 485
 486         if (skb_is_gso(skb)) {
 487                 struct skb_shared_info *sinfo = skb_shinfo(skb);
 488
 489                 /* This is a hint as to how much should be linear. */
 490                 vnet_hdr->hdr_len = skb_headlen(skb);
 491                 vnet_hdr->gso_size = sinfo->gso_size;
 492                 if (sinfo->gso_type & SKB_GSO_TCPV4)
 493                         vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
 494                 else if (sinfo->gso_type & SKB_GSO_TCPV6)
 495                         vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
 496                 else if (sinfo->gso_type & SKB_GSO_UDP)
 497                         vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
 498                 else
 499                         BUG();
 500                 if (sinfo->gso_type & SKB_GSO_TCP_ECN)
 501                         vnet_hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
 502         } else
 503                 vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
 504
 505         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 506                 vnet_hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
 507                 vnet_hdr->csum_start = skb_checksum_start_offset(skb);
 508                 vnet_hdr->csum_offset = skb->csum_offset;
 509         } /* else everything is zero */
 510
 511         return 0;
 512 }
 513
 514
 515 /* Get packet from user space buffer */
 516 static ssize_t macvtap_get_user(struct macvtap_queue *q,
 517                                 const struct iovec *iv, size_t count,
 518                                 int noblock)
 519 {
 520         struct sk_buff *skb;
 521         struct macvlan_dev *vlan;
 522         size_t len = count;
 523         int err;
 524         struct virtio_net_hdr vnet_hdr = { 0 };
 525         int vnet_hdr_len = 0;
 526
 527         if (q->flags & IFF_VNET_HDR) {
 528                 vnet_hdr_len = q->vnet_hdr_sz;
 529
 530                 err = -EINVAL;
 531                 if ((len -= vnet_hdr_len) < 0)
 532                         goto err;
 533
 534                 err = memcpy_fromiovecend((void *)&vnet_hdr, iv, 0,
 535                                            sizeof(vnet_hdr));
 536                 if (err < 0)
 537                         goto err;
 538                 if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
 539                      vnet_hdr.csum_start + vnet_hdr.csum_offset + 2 >
 540                                                         vnet_hdr.hdr_len)
 541                         vnet_hdr.hdr_len = vnet_hdr.csum_start +
 542                                                 vnet_hdr.csum_offset + 2;
 543                 err = -EINVAL;
 544                 if (vnet_hdr.hdr_len > len)
 545                         goto err;
 546         }
 547
 548         err = -EINVAL;
 549         if (unlikely(len < ETH_HLEN))
 550                 goto err;
 551
 552         skb = macvtap_alloc_skb(&q->sk, NET_IP_ALIGN, len, vnet_hdr.hdr_len,
 553                                 noblock, &err);
 554         if (!skb)
 555                 goto err;
 556
 557         err = skb_copy_datagram_from_iovec(skb, 0, iv, vnet_hdr_len, len);
 558         if (err)
 559                 goto err_kfree;
 560
 561         skb_set_network_header(skb, ETH_HLEN);
 562         skb_reset_mac_header(skb);
 563         skb->protocol = eth_hdr(skb)->h_proto;
 564
 565         if (vnet_hdr_len) {
 566                 err = macvtap_skb_from_vnet_hdr(skb, &vnet_hdr);
 567                 if (err)
 568                         goto err_kfree;
 569         }
 570
 571         rcu_read_lock_bh();
 572         vlan = rcu_dereference(q->vlan);
 573         if (vlan)
 574                 macvlan_start_xmit(skb, vlan->dev);
 575         else
 576                 kfree_skb(skb);
 577         rcu_read_unlock_bh();
 578
 579         return count;
 580
 581 err_kfree:
 582         kfree_skb(skb);
 583
 584 err:
 585         rcu_read_lock_bh();
 586         vlan = rcu_dereference(q->vlan);
 587         if (vlan)
 588                 netdev_get_tx_queue(vlan->dev, 0)->tx_dropped++;
 589         rcu_read_unlock_bh();
 590
 591         return err;
 592 }
 593
 594 static ssize_t macvtap_aio_write(struct kiocb *iocb, const struct iovec *iv,
 595                                  unsigned long count, loff_t pos)
 596 {
 597         struct file *file = iocb->ki_filp;
 598         ssize_t result = -ENOLINK;
 599         struct macvtap_queue *q = file->private_data;
 600
 601         result = macvtap_get_user(q, iv, iov_length(iv, count),
 602                               file->f_flags & O_NONBLOCK);
 603         return result;
 604 }
 605
 606 /* Put packet to the user space buffer */
 607 static ssize_t macvtap_put_user(struct macvtap_queue *q,
 608                                 const struct sk_buff *skb,
 609                                 const struct iovec *iv, int len)
 610 {
 611         struct macvlan_dev *vlan;
 612         int ret;
 613         int vnet_hdr_len = 0;
 614
 615         if (q->flags & IFF_VNET_HDR) {
 616                 struct virtio_net_hdr vnet_hdr;
 617                 vnet_hdr_len = q->vnet_hdr_sz;
 618                 if ((len -= vnet_hdr_len) < 0)
 619                         return -EINVAL;
 620
 621                 ret = macvtap_skb_to_vnet_hdr(skb, &vnet_hdr);
 622                 if (ret)
 623                         return ret;
 624
 625                 if (memcpy_toiovecend(iv, (void *)&vnet_hdr, 0, sizeof(vnet_hdr)))
 626                         return -EFAULT;
 627         }
 628
 629         len = min_t(int, skb->len, len);
 630
 631         ret = skb_copy_datagram_const_iovec(skb, 0, iv, vnet_hdr_len, len);
 632
 633         rcu_read_lock_bh();
 634         vlan = rcu_dereference(q->vlan);
 635         if (vlan)
 636                 macvlan_count_rx(vlan, len, ret == 0, 0);
 637         rcu_read_unlock_bh();
 638
 639         return ret ? ret : (len + vnet_hdr_len);
 640 }
 641
 642 static ssize_t macvtap_do_read(struct macvtap_queue *q, struct kiocb *iocb,
 643                                const struct iovec *iv, unsigned long len,
 644                                int noblock)
 645 {
 646         DECLARE_WAITQUEUE(wait, current);
 647         struct sk_buff *skb;
 648         ssize_t ret = 0;
 649
 650         add_wait_queue(sk_sleep(&q->sk), &wait);
 651         while (len) {
 652                 current->state = TASK_INTERRUPTIBLE;
 653
 654                 /* Read frames from the queue */
 655                 skb = skb_dequeue(&q->sk.sk_receive_queue);
 656                 if (!skb) {
 657                         if (noblock) {
 658                                 ret = -EAGAIN;
 659                                 break;
 660                         }
 661                         if (signal_pending(current)) {
 662                                 ret = -ERESTARTSYS;
 663                                 break;
 664                         }
 665                         /* Nothing to read, let's sleep */
 666                         schedule();
 667                         continue;
 668                 }
 669                 ret = macvtap_put_user(q, skb, iv, len);
 670                 kfree_skb(skb);
 671                 break;
 672         }
 673
 674         current->state = TASK_RUNNING;
 675         remove_wait_queue(sk_sleep(&q->sk), &wait);
 676         return ret;
 677 }
 678
 679 static ssize_t macvtap_aio_read(struct kiocb *iocb, const struct iovec *iv,
 680                                 unsigned long count, loff_t pos)
 681 {
 682         struct file *file = iocb->ki_filp;
 683         struct macvtap_queue *q = file->private_data;
 684         ssize_t len, ret = 0;
 685
 686         len = iov_length(iv, count);
 687         if (len < 0) {
 688                 ret = -EINVAL;
 689                 goto out;
 690         }
 691
 692         ret = macvtap_do_read(q, iocb, iv, len, file->f_flags & O_NONBLOCK);
 693         ret = min_t(ssize_t, ret, len); /* XXX copied from tun.c. Why? */
 694 out:
 695         return ret;
 696 }
 697
 698 /*
 699  * provide compatibility with generic tun/tap interface
 700  */
 701 static long macvtap_ioctl(struct file *file, unsigned int cmd,
 702                           unsigned long arg)
 703 {
 704         struct macvtap_queue *q = file->private_data;
 705         struct macvlan_dev *vlan;
 706         void __user *argp = (void __user *)arg;
 707         struct ifreq __user *ifr = argp;
 708         unsigned int __user *up = argp;
 709         unsigned int u;
 710         int __user *sp = argp;
 711         int s;
 712         int ret;
 713
 714         switch (cmd) {
 715         case TUNSETIFF:
 716                 /* ignore the name, just look at flags */
 717                 if (get_user(u, &ifr->ifr_flags))
 718                         return -EFAULT;
 719
 720                 ret = 0;
 721                 if ((u & ~IFF_VNET_HDR) != (IFF_NO_PI | IFF_TAP))
 722                         ret = -EINVAL;
 723                 else
 724                         q->flags = u;
 725
 726                 return ret;
 727
 728         case TUNGETIFF:
 729                 rcu_read_lock_bh();
 730                 vlan = rcu_dereference(q->vlan);
 731                 if (vlan)
 732                         dev_hold(vlan->dev);
 733                 rcu_read_unlock_bh();
 734
 735                 if (!vlan)
 736                         return -ENOLINK;
 737
 738                 ret = 0;
 739                 if (copy_to_user(&ifr->ifr_name, q->vlan->dev->name, IFNAMSIZ) ||
 740                     put_user(q->flags, &ifr->ifr_flags))
 741                         ret = -EFAULT;
 742                 dev_put(vlan->dev);
 743                 return ret;
 744
 745         case TUNGETFEATURES:
 746                 if (put_user(IFF_TAP | IFF_NO_PI | IFF_VNET_HDR, up))
 747                         return -EFAULT;
 748                 return 0;
 749
 750         case TUNSETSNDBUF:
 751                 if (get_user(u, up))
 752                         return -EFAULT;
 753
 754                 q->sk.sk_sndbuf = u;
 755                 return 0;
 756
 757         case TUNGETVNETHDRSZ:
 758                 s = q->vnet_hdr_sz;
 759                 if (put_user(s, sp))
 760                         return -EFAULT;
 761                 return 0;
 762
 763         case TUNSETVNETHDRSZ:
 764                 if (get_user(s, sp))
 765                         return -EFAULT;
 766                 if (s < (int)sizeof(struct virtio_net_hdr))
 767                         return -EINVAL;
 768
 769                 q->vnet_hdr_sz = s;
 770                 return 0;
 771
 772         case TUNSETOFFLOAD:
 773                 /* let the user check for future flags */
 774                 if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
 775                             TUN_F_TSO_ECN | TUN_F_UFO))
 776                         return -EINVAL;
 777
 778                 /* TODO: only accept frames with the features that
 779                          got enabled for forwarded frames */
 780                 if (!(q->flags & IFF_VNET_HDR))
 781                         return  -EINVAL;
 782                 return 0;
 783
 784         default:
 785                 return -EINVAL;
 786         }
 787 }
 788
 789 #ifdef CONFIG_COMPAT
 790 static long macvtap_compat_ioctl(struct file *file, unsigned int cmd,
 791                                  unsigned long arg)
 792 {
 793         return macvtap_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
 794 }
 795 #endif
 796
 797 static const struct file_operations macvtap_fops = {
 798         .owner          = THIS_MODULE,
 799         .open           = macvtap_open,
 800         .release        = macvtap_release,
 801         .aio_read       = macvtap_aio_read,
 802         .aio_write      = macvtap_aio_write,
 803         .poll           = macvtap_poll,
 804         .llseek         = no_llseek,
 805         .unlocked_ioctl = macvtap_ioctl,
 806 #ifdef CONFIG_COMPAT
 807         .compat_ioctl   = macvtap_compat_ioctl,
 808 #endif
 809 };
 810
 811 static int macvtap_sendmsg(struct kiocb *iocb, struct socket *sock,
 812                            struct msghdr *m, size_t total_len)
 813 {
 814         struct macvtap_queue *q = container_of(sock, struct macvtap_queue, sock);
 815         return macvtap_get_user(q, m->msg_iov, total_len,
 816                             m->msg_flags & MSG_DONTWAIT);
 817 }
 818
 819 static int macvtap_recvmsg(struct kiocb *iocb, struct socket *sock,
 820                            struct msghdr *m, size_t total_len,
 821                            int flags)
 822 {
 823         struct macvtap_queue *q = container_of(sock, struct macvtap_queue, sock);
 824         int ret;
 825         if (flags & ~(MSG_DONTWAIT|MSG_TRUNC))
 826                 return -EINVAL;
 827         ret = macvtap_do_read(q, iocb, m->msg_iov, total_len,
 828                           flags & MSG_DONTWAIT);
 829         if (ret > total_len) {
 830                 m->msg_flags |= MSG_TRUNC;
 831                 ret = flags & MSG_TRUNC ? ret : total_len;
 832         }
 833         return ret;
 834 }
 835
 836 /* Ops structure to mimic raw sockets with tun */
 837 static const struct proto_ops macvtap_socket_ops = {
 838         .sendmsg = macvtap_sendmsg,
 839         .recvmsg = macvtap_recvmsg,
 840 };
 841
 842 /* Get an underlying socket object from tun file.  Returns error unless file is
 843  * attached to a device.  The returned object works like a packet socket, it
 844  * can be used for sock_sendmsg/sock_recvmsg.  The caller is responsible for
 845  * holding a reference to the file for as long as the socket is in use. */
 846 struct socket *macvtap_get_socket(struct file *file)
 847 {
 848         struct macvtap_queue *q;
 849         if (file->f_op != &macvtap_fops)
 850                 return ERR_PTR(-EINVAL);
 851         q = file->private_data;
 852         if (!q)
 853                 return ERR_PTR(-EBADFD);
 854         return &q->sock;
 855 }
 856 EXPORT_SYMBOL_GPL(macvtap_get_socket);
 857
 858 static int macvtap_init(void)
 859 {
 860         int err;
 861
 862         err = alloc_chrdev_region(&macvtap_major, 0,
 863                                 MACVTAP_NUM_DEVS, "macvtap");
 864         if (err)
 865                 goto out1;
 866
 867         cdev_init(&macvtap_cdev, &macvtap_fops);
 868         err = cdev_add(&macvtap_cdev, macvtap_major, MACVTAP_NUM_DEVS);
 869         if (err)
 870                 goto out2;
 871
 872         macvtap_class = class_create(THIS_MODULE, "macvtap");
 873         if (IS_ERR(macvtap_class)) {
 874                 err = PTR_ERR(macvtap_class);
 875                 goto out3;
 876         }
 877
 878         err = macvlan_link_register(&macvtap_link_ops);
 879         if (err)
 880                 goto out4;
 881
 882         return 0;
 883
 884 out4:
 885         class_unregister(macvtap_class);
 886 out3:
 887         cdev_del(&macvtap_cdev);
 888 out2:
 889         unregister_chrdev_region(macvtap_major, MACVTAP_NUM_DEVS);
 890 out1:
 891         return err;
 892 }
 893 module_init(macvtap_init);
 894
 895 static void macvtap_exit(void)
 896 {
 897         rtnl_link_unregister(&macvtap_link_ops);
 898         class_unregister(macvtap_class);
 899         cdev_del(&macvtap_cdev);
 900         unregister_chrdev_region(macvtap_major, MACVTAP_NUM_DEVS);
 901 }
 902 module_exit(macvtap_exit);
 903
 904 MODULE_ALIAS_RTNL_LINK("macvtap");
 905 MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>");
 906 MODULE_LICENSE("GPL");