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