nbd/server.c

   1 /*
   2  *  Copyright (C) 2005  Anthony Liguori <anthony@codemonkey.ws>
   3  *
   4  *  Network Block Device Server Side
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; under version 2 of the License.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include "qemu/osdep.h"
  20 #include "qapi/error.h"
  21 #include "nbd-internal.h"
  22
  23 static int system_errno_to_nbd_errno(int err)
  24 {
  25     switch (err) {
  26     case 0:
  27         return NBD_SUCCESS;
  28     case EPERM:
  29     case EROFS:
  30         return NBD_EPERM;
  31     case EIO:
  32         return NBD_EIO;
  33     case ENOMEM:
  34         return NBD_ENOMEM;
  35 #ifdef EDQUOT
  36     case EDQUOT:
  37 #endif
  38     case EFBIG:
  39     case ENOSPC:
  40         return NBD_ENOSPC;
  41     case EINVAL:
  42     default:
  43         return NBD_EINVAL;
  44     }
  45 }
  46
  47 /* Definitions for opaque data types */
  48
  49 typedef struct NBDRequest NBDRequest;
  50
  51 struct NBDRequest {
  52     QSIMPLEQ_ENTRY(NBDRequest) entry;
  53     NBDClient *client;
  54     uint8_t *data;
  55 };
  56
  57 struct NBDExport {
  58     int refcount;
  59     void (*close)(NBDExport *exp);
  60
  61     BlockBackend *blk;
  62     char *name;
  63     off_t dev_offset;
  64     off_t size;
  65     uint32_t nbdflags;
  66     QTAILQ_HEAD(, NBDClient) clients;
  67     QTAILQ_ENTRY(NBDExport) next;
  68
  69     AioContext *ctx;
  70
  71     Notifier eject_notifier;
  72 };
  73
  74 static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
  75
  76 struct NBDClient {
  77     int refcount;
  78     void (*close)(NBDClient *client);
  79
  80     NBDExport *exp;
  81     QCryptoTLSCreds *tlscreds;
  82     char *tlsaclname;
  83     QIOChannelSocket *sioc; /* The underlying data channel */
  84     QIOChannel *ioc; /* The current I/O channel which may differ (eg TLS) */
  85
  86     Coroutine *recv_coroutine;
  87
  88     CoMutex send_lock;
  89     Coroutine *send_coroutine;
  90
  91     bool can_read;
  92
  93     QTAILQ_ENTRY(NBDClient) next;
  94     int nb_requests;
  95     bool closing;
  96 };
  97
  98 /* That's all folks */
  99
 100 static void nbd_set_handlers(NBDClient *client);
 101 static void nbd_unset_handlers(NBDClient *client);
 102 static void nbd_update_can_read(NBDClient *client);
 103
 104 static gboolean nbd_negotiate_continue(QIOChannel *ioc,
 105                                        GIOCondition condition,
 106                                        void *opaque)
 107 {
 108     qemu_coroutine_enter(opaque, NULL);
 109     return TRUE;
 110 }
 111
 112 static ssize_t nbd_negotiate_read(QIOChannel *ioc, void *buffer, size_t size)
 113 {
 114     ssize_t ret;
 115     guint watch;
 116
 117     assert(qemu_in_coroutine());
 118     /* Negotiation are always in main loop. */
 119     watch = qio_channel_add_watch(ioc,
 120                                   G_IO_IN,
 121                                   nbd_negotiate_continue,
 122                                   qemu_coroutine_self(),
 123                                   NULL);
 124     ret = read_sync(ioc, buffer, size);
 125     g_source_remove(watch);
 126     return ret;
 127
 128 }
 129
 130 static ssize_t nbd_negotiate_write(QIOChannel *ioc, void *buffer, size_t size)
 131 {
 132     ssize_t ret;
 133     guint watch;
 134
 135     assert(qemu_in_coroutine());
 136     /* Negotiation are always in main loop. */
 137     watch = qio_channel_add_watch(ioc,
 138                                   G_IO_OUT,
 139                                   nbd_negotiate_continue,
 140                                   qemu_coroutine_self(),
 141                                   NULL);
 142     ret = write_sync(ioc, buffer, size);
 143     g_source_remove(watch);
 144     return ret;
 145 }
 146
 147 static ssize_t nbd_negotiate_drop_sync(QIOChannel *ioc, size_t size)
 148 {
 149     ssize_t ret, dropped = size;
 150     uint8_t *buffer = g_malloc(MIN(65536, size));
 151
 152     while (size > 0) {
 153         ret = nbd_negotiate_read(ioc, buffer, MIN(65536, size));
 154         if (ret < 0) {
 155             g_free(buffer);
 156             return ret;
 157         }
 158
 159         assert(ret <= size);
 160         size -= ret;
 161     }
 162
 163     g_free(buffer);
 164     return dropped;
 165 }
 166
 167 /* Basic flow for negotiation
 168
 169    Server         Client
 170    Negotiate
 171
 172    or
 173
 174    Server         Client
 175    Negotiate #1
 176                   Option
 177    Negotiate #2
 178
 179    ----
 180
 181    followed by
 182
 183    Server         Client
 184                   Request
 185    Response
 186                   Request
 187    Response
 188                   ...
 189    ...
 190                   Request (type == 2)
 191
 192 */
 193
 194 static int nbd_negotiate_send_rep(QIOChannel *ioc, uint32_t type, uint32_t opt)
 195 {
 196     uint64_t magic;
 197     uint32_t len;
 198
 199     TRACE("Reply opt=%x type=%x", type, opt);
 200
 201     magic = cpu_to_be64(NBD_REP_MAGIC);
 202     if (nbd_negotiate_write(ioc, &magic, sizeof(magic)) != sizeof(magic)) {
 203         LOG("write failed (rep magic)");
 204         return -EINVAL;
 205     }
 206     opt = cpu_to_be32(opt);
 207     if (nbd_negotiate_write(ioc, &opt, sizeof(opt)) != sizeof(opt)) {
 208         LOG("write failed (rep opt)");
 209         return -EINVAL;
 210     }
 211     type = cpu_to_be32(type);
 212     if (nbd_negotiate_write(ioc, &type, sizeof(type)) != sizeof(type)) {
 213         LOG("write failed (rep type)");
 214         return -EINVAL;
 215     }
 216     len = cpu_to_be32(0);
 217     if (nbd_negotiate_write(ioc, &len, sizeof(len)) != sizeof(len)) {
 218         LOG("write failed (rep data length)");
 219         return -EINVAL;
 220     }
 221     return 0;
 222 }
 223
 224 static int nbd_negotiate_send_rep_list(QIOChannel *ioc, NBDExport *exp)
 225 {
 226     uint64_t magic, name_len;
 227     uint32_t opt, type, len;
 228
 229     TRACE("Advertizing export name '%s'", exp->name ? exp->name : "");
 230     name_len = strlen(exp->name);
 231     magic = cpu_to_be64(NBD_REP_MAGIC);
 232     if (nbd_negotiate_write(ioc, &magic, sizeof(magic)) != sizeof(magic)) {
 233         LOG("write failed (magic)");
 234         return -EINVAL;
 235      }
 236     opt = cpu_to_be32(NBD_OPT_LIST);
 237     if (nbd_negotiate_write(ioc, &opt, sizeof(opt)) != sizeof(opt)) {
 238         LOG("write failed (opt)");
 239         return -EINVAL;
 240     }
 241     type = cpu_to_be32(NBD_REP_SERVER);
 242     if (nbd_negotiate_write(ioc, &type, sizeof(type)) != sizeof(type)) {
 243         LOG("write failed (reply type)");
 244         return -EINVAL;
 245     }
 246     len = cpu_to_be32(name_len + sizeof(len));
 247     if (nbd_negotiate_write(ioc, &len, sizeof(len)) != sizeof(len)) {
 248         LOG("write failed (length)");
 249         return -EINVAL;
 250     }
 251     len = cpu_to_be32(name_len);
 252     if (nbd_negotiate_write(ioc, &len, sizeof(len)) != sizeof(len)) {
 253         LOG("write failed (length)");
 254         return -EINVAL;
 255     }
 256     if (nbd_negotiate_write(ioc, exp->name, name_len) != name_len) {
 257         LOG("write failed (buffer)");
 258         return -EINVAL;
 259     }
 260     return 0;
 261 }
 262
 263 static int nbd_negotiate_handle_list(NBDClient *client, uint32_t length)
 264 {
 265     NBDExport *exp;
 266
 267     if (length) {
 268         if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
 269             return -EIO;
 270         }
 271         return nbd_negotiate_send_rep(client->ioc,
 272                                       NBD_REP_ERR_INVALID, NBD_OPT_LIST);
 273     }
 274
 275     /* For each export, send a NBD_REP_SERVER reply. */
 276     QTAILQ_FOREACH(exp, &exports, next) {
 277         if (nbd_negotiate_send_rep_list(client->ioc, exp)) {
 278             return -EINVAL;
 279         }
 280     }
 281     /* Finish with a NBD_REP_ACK. */
 282     return nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, NBD_OPT_LIST);
 283 }
 284
 285 static int nbd_negotiate_handle_export_name(NBDClient *client, uint32_t length)
 286 {
 287     int rc = -EINVAL;
 288     char name[256];
 289
 290     /* Client sends:
 291         [20 ..  xx]   export name (length bytes)
 292      */
 293     TRACE("Checking length");
 294     if (length > 255) {
 295         LOG("Bad length received");
 296         goto fail;
 297     }
 298     if (nbd_negotiate_read(client->ioc, name, length) != length) {
 299         LOG("read failed");
 300         goto fail;
 301     }
 302     name[length] = '\0';
 303
 304     TRACE("Client requested export '%s'", name);
 305
 306     client->exp = nbd_export_find(name);
 307     if (!client->exp) {
 308         LOG("export not found");
 309         goto fail;
 310     }
 311
 312     QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
 313     nbd_export_get(client->exp);
 314     rc = 0;
 315 fail:
 316     return rc;
 317 }
 318
 319
 320 static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client,
 321                                                  uint32_t length)
 322 {
 323     QIOChannel *ioc;
 324     QIOChannelTLS *tioc;
 325     struct NBDTLSHandshakeData data = { 0 };
 326
 327     TRACE("Setting up TLS");
 328     ioc = client->ioc;
 329     if (length) {
 330         if (nbd_negotiate_drop_sync(ioc, length) != length) {
 331             return NULL;
 332         }
 333         nbd_negotiate_send_rep(ioc, NBD_REP_ERR_INVALID, NBD_OPT_STARTTLS);
 334         return NULL;
 335     }
 336
 337     nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, NBD_OPT_STARTTLS);
 338
 339     tioc = qio_channel_tls_new_server(ioc,
 340                                       client->tlscreds,
 341                                       client->tlsaclname,
 342                                       NULL);
 343     if (!tioc) {
 344         return NULL;
 345     }
 346
 347     TRACE("Starting TLS handshake");
 348     data.loop = g_main_loop_new(g_main_context_default(), FALSE);
 349     qio_channel_tls_handshake(tioc,
 350                               nbd_tls_handshake,
 351                               &data,
 352                               NULL);
 353
 354     if (!data.complete) {
 355         g_main_loop_run(data.loop);
 356     }
 357     g_main_loop_unref(data.loop);
 358     if (data.error) {
 359         object_unref(OBJECT(tioc));
 360         error_free(data.error);
 361         return NULL;
 362     }
 363
 364     return QIO_CHANNEL(tioc);
 365 }
 366
 367
 368 static int nbd_negotiate_options(NBDClient *client)
 369 {
 370     uint32_t flags;
 371     bool fixedNewstyle = false;
 372
 373     /* Client sends:
 374         [ 0 ..   3]   client flags
 375
 376         [ 0 ..   7]   NBD_OPTS_MAGIC
 377         [ 8 ..  11]   NBD option
 378         [12 ..  15]   Data length
 379         ...           Rest of request
 380
 381         [ 0 ..   7]   NBD_OPTS_MAGIC
 382         [ 8 ..  11]   Second NBD option
 383         [12 ..  15]   Data length
 384         ...           Rest of request
 385     */
 386
 387     if (nbd_negotiate_read(client->ioc, &flags, sizeof(flags)) !=
 388         sizeof(flags)) {
 389         LOG("read failed");
 390         return -EIO;
 391     }
 392     TRACE("Checking client flags");
 393     be32_to_cpus(&flags);
 394     if (flags & NBD_FLAG_C_FIXED_NEWSTYLE) {
 395         TRACE("Support supports fixed newstyle handshake");
 396         fixedNewstyle = true;
 397         flags &= ~NBD_FLAG_C_FIXED_NEWSTYLE;
 398     }
 399     if (flags != 0) {
 400         TRACE("Unknown client flags 0x%x received", flags);
 401         return -EIO;
 402     }
 403
 404     while (1) {
 405         int ret;
 406         uint32_t clientflags, length;
 407         uint64_t magic;
 408
 409         if (nbd_negotiate_read(client->ioc, &magic, sizeof(magic)) !=
 410             sizeof(magic)) {
 411             LOG("read failed");
 412             return -EINVAL;
 413         }
 414         TRACE("Checking opts magic");
 415         if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) {
 416             LOG("Bad magic received");
 417             return -EINVAL;
 418         }
 419
 420         if (nbd_negotiate_read(client->ioc, &clientflags,
 421                                sizeof(clientflags)) != sizeof(clientflags)) {
 422             LOG("read failed");
 423             return -EINVAL;
 424         }
 425         clientflags = be32_to_cpu(clientflags);
 426
 427         if (nbd_negotiate_read(client->ioc, &length, sizeof(length)) !=
 428             sizeof(length)) {
 429             LOG("read failed");
 430             return -EINVAL;
 431         }
 432         length = be32_to_cpu(length);
 433
 434         TRACE("Checking option 0x%x", clientflags);
 435         if (client->tlscreds &&
 436             client->ioc == (QIOChannel *)client->sioc) {
 437             QIOChannel *tioc;
 438             if (!fixedNewstyle) {
 439                 TRACE("Unsupported option 0x%x", clientflags);
 440                 return -EINVAL;
 441             }
 442             switch (clientflags) {
 443             case NBD_OPT_STARTTLS:
 444                 tioc = nbd_negotiate_handle_starttls(client, length);
 445                 if (!tioc) {
 446                     return -EIO;
 447                 }
 448                 object_unref(OBJECT(client->ioc));
 449                 client->ioc = QIO_CHANNEL(tioc);
 450                 break;
 451
 452             default:
 453                 TRACE("Option 0x%x not permitted before TLS", clientflags);
 454                 nbd_negotiate_send_rep(client->ioc, NBD_REP_ERR_TLS_REQD,
 455                                        clientflags);
 456                 return -EINVAL;
 457             }
 458         } else if (fixedNewstyle) {
 459             switch (clientflags) {
 460             case NBD_OPT_LIST:
 461                 ret = nbd_negotiate_handle_list(client, length);
 462                 if (ret < 0) {
 463                     return ret;
 464                 }
 465                 break;
 466
 467             case NBD_OPT_ABORT:
 468                 return -EINVAL;
 469
 470             case NBD_OPT_EXPORT_NAME:
 471                 return nbd_negotiate_handle_export_name(client, length);
 472
 473             case NBD_OPT_STARTTLS:
 474                 if (client->tlscreds) {
 475                     TRACE("TLS already enabled");
 476                     nbd_negotiate_send_rep(client->ioc, NBD_REP_ERR_INVALID,
 477                                            clientflags);
 478                 } else {
 479                     TRACE("TLS not configured");
 480                     nbd_negotiate_send_rep(client->ioc, NBD_REP_ERR_POLICY,
 481                                            clientflags);
 482                 }
 483                 return -EINVAL;
 484             default:
 485                 TRACE("Unsupported option 0x%x", clientflags);
 486                 if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
 487                     return -EIO;
 488                 }
 489                 nbd_negotiate_send_rep(client->ioc, NBD_REP_ERR_UNSUP,
 490                                        clientflags);
 491                 break;
 492             }
 493         } else {
 494             /*
 495              * If broken new-style we should drop the connection
 496              * for anything except NBD_OPT_EXPORT_NAME
 497              */
 498             switch (clientflags) {
 499             case NBD_OPT_EXPORT_NAME:
 500                 return nbd_negotiate_handle_export_name(client, length);
 501
 502             default:
 503                 TRACE("Unsupported option 0x%x", clientflags);
 504                 return -EINVAL;
 505             }
 506         }
 507     }
 508 }
 509
 510 typedef struct {
 511     NBDClient *client;
 512     Coroutine *co;
 513 } NBDClientNewData;
 514
 515 static coroutine_fn int nbd_negotiate(NBDClientNewData *data)
 516 {
 517     NBDClient *client = data->client;
 518     char buf[8 + 8 + 8 + 128];
 519     int rc;
 520     const int myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM |
 521                          NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA);
 522     bool oldStyle;
 523
 524     /* Old style negotiation header without options
 525         [ 0 ..   7]   passwd       ("NBDMAGIC")
 526         [ 8 ..  15]   magic        (NBD_CLIENT_MAGIC)
 527         [16 ..  23]   size
 528         [24 ..  25]   server flags (0)
 529         [26 ..  27]   export flags
 530         [28 .. 151]   reserved     (0)
 531
 532        New style negotiation header with options
 533         [ 0 ..   7]   passwd       ("NBDMAGIC")
 534         [ 8 ..  15]   magic        (NBD_OPTS_MAGIC)
 535         [16 ..  17]   server flags (0)
 536         ....options sent....
 537         [18 ..  25]   size
 538         [26 ..  27]   export flags
 539         [28 .. 151]   reserved     (0)
 540      */
 541
 542     qio_channel_set_blocking(client->ioc, false, NULL);
 543     rc = -EINVAL;
 544
 545     TRACE("Beginning negotiation.");
 546     memset(buf, 0, sizeof(buf));
 547     memcpy(buf, "NBDMAGIC", 8);
 548
 549     oldStyle = client->exp != NULL && !client->tlscreds;
 550     if (oldStyle) {
 551         assert ((client->exp->nbdflags & ~65535) == 0);
 552         stq_be_p(buf + 8, NBD_CLIENT_MAGIC);
 553         stq_be_p(buf + 16, client->exp->size);
 554         stw_be_p(buf + 26, client->exp->nbdflags | myflags);
 555     } else {
 556         stq_be_p(buf + 8, NBD_OPTS_MAGIC);
 557         stw_be_p(buf + 16, NBD_FLAG_FIXED_NEWSTYLE);
 558     }
 559
 560     if (oldStyle) {
 561         if (client->tlscreds) {
 562             TRACE("TLS cannot be enabled with oldstyle protocol");
 563             goto fail;
 564         }
 565         if (nbd_negotiate_write(client->ioc, buf, sizeof(buf)) != sizeof(buf)) {
 566             LOG("write failed");
 567             goto fail;
 568         }
 569     } else {
 570         if (nbd_negotiate_write(client->ioc, buf, 18) != 18) {
 571             LOG("write failed");
 572             goto fail;
 573         }
 574         rc = nbd_negotiate_options(client);
 575         if (rc != 0) {
 576             LOG("option negotiation failed");
 577             goto fail;
 578         }
 579
 580         assert ((client->exp->nbdflags & ~65535) == 0);
 581         stq_be_p(buf + 18, client->exp->size);
 582         stw_be_p(buf + 26, client->exp->nbdflags | myflags);
 583         if (nbd_negotiate_write(client->ioc, buf + 18, sizeof(buf) - 18) !=
 584             sizeof(buf) - 18) {
 585             LOG("write failed");
 586             goto fail;
 587         }
 588     }
 589
 590     TRACE("Negotiation succeeded.");
 591     rc = 0;
 592 fail:
 593     return rc;
 594 }
 595
 596 #ifdef __linux__
 597
 598 int nbd_disconnect(int fd)
 599 {
 600     ioctl(fd, NBD_CLEAR_QUE);
 601     ioctl(fd, NBD_DISCONNECT);
 602     ioctl(fd, NBD_CLEAR_SOCK);
 603     return 0;
 604 }
 605
 606 #else
 607
 608 int nbd_disconnect(int fd)
 609 {
 610     return -ENOTSUP;
 611 }
 612 #endif
 613
 614 static ssize_t nbd_receive_request(QIOChannel *ioc, struct nbd_request *request)
 615 {
 616     uint8_t buf[NBD_REQUEST_SIZE];
 617     uint32_t magic;
 618     ssize_t ret;
 619
 620     ret = read_sync(ioc, buf, sizeof(buf));
 621     if (ret < 0) {
 622         return ret;
 623     }
 624
 625     if (ret != sizeof(buf)) {
 626         LOG("read failed");
 627         return -EINVAL;
 628     }
 629
 630     /* Request
 631        [ 0 ..  3]   magic   (NBD_REQUEST_MAGIC)
 632        [ 4 ..  7]   type    (0 == READ, 1 == WRITE)
 633        [ 8 .. 15]   handle
 634        [16 .. 23]   from
 635        [24 .. 27]   len
 636      */
 637
 638     magic = be32_to_cpup((uint32_t*)buf);
 639     request->type  = be32_to_cpup((uint32_t*)(buf + 4));
 640     request->handle = be64_to_cpup((uint64_t*)(buf + 8));
 641     request->from  = be64_to_cpup((uint64_t*)(buf + 16));
 642     request->len   = be32_to_cpup((uint32_t*)(buf + 24));
 643
 644     TRACE("Got request: "
 645           "{ magic = 0x%x, .type = %d, from = %" PRIu64" , len = %u }",
 646           magic, request->type, request->from, request->len);
 647
 648     if (magic != NBD_REQUEST_MAGIC) {
 649         LOG("invalid magic (got 0x%x)", magic);
 650         return -EINVAL;
 651     }
 652     return 0;
 653 }
 654
 655 static ssize_t nbd_send_reply(QIOChannel *ioc, struct nbd_reply *reply)
 656 {
 657     uint8_t buf[NBD_REPLY_SIZE];
 658     ssize_t ret;
 659
 660     reply->error = system_errno_to_nbd_errno(reply->error);
 661
 662     TRACE("Sending response to client: { .error = %d, handle = %" PRIu64 " }",
 663           reply->error, reply->handle);
 664
 665     /* Reply
 666        [ 0 ..  3]    magic   (NBD_REPLY_MAGIC)
 667        [ 4 ..  7]    error   (0 == no error)
 668        [ 7 .. 15]    handle
 669      */
 670     stl_be_p(buf, NBD_REPLY_MAGIC);
 671     stl_be_p(buf + 4, reply->error);
 672     stq_be_p(buf + 8, reply->handle);
 673
 674     ret = write_sync(ioc, buf, sizeof(buf));
 675     if (ret < 0) {
 676         return ret;
 677     }
 678
 679     if (ret != sizeof(buf)) {
 680         LOG("writing to socket failed");
 681         return -EINVAL;
 682     }
 683     return 0;
 684 }
 685
 686 #define MAX_NBD_REQUESTS 16
 687
 688 void nbd_client_get(NBDClient *client)
 689 {
 690     client->refcount++;
 691 }
 692
 693 void nbd_client_put(NBDClient *client)
 694 {
 695     if (--client->refcount == 0) {
 696         /* The last reference should be dropped by client->close,
 697          * which is called by client_close.
 698          */
 699         assert(client->closing);
 700
 701         nbd_unset_handlers(client);
 702         object_unref(OBJECT(client->sioc));
 703         object_unref(OBJECT(client->ioc));
 704         if (client->tlscreds) {
 705             object_unref(OBJECT(client->tlscreds));
 706         }
 707         g_free(client->tlsaclname);
 708         if (client->exp) {
 709             QTAILQ_REMOVE(&client->exp->clients, client, next);
 710             nbd_export_put(client->exp);
 711         }
 712         g_free(client);
 713     }
 714 }
 715
 716 static void client_close(NBDClient *client)
 717 {
 718     if (client->closing) {
 719         return;
 720     }
 721
 722     client->closing = true;
 723
 724     /* Force requests to finish.  They will drop their own references,
 725      * then we'll close the socket and free the NBDClient.
 726      */
 727     qio_channel_shutdown(client->ioc, QIO_CHANNEL_SHUTDOWN_BOTH,
 728                          NULL);
 729
 730     /* Also tell the client, so that they release their reference.  */
 731     if (client->close) {
 732         client->close(client);
 733     }
 734 }
 735
 736 static NBDRequest *nbd_request_get(NBDClient *client)
 737 {
 738     NBDRequest *req;
 739
 740     assert(client->nb_requests <= MAX_NBD_REQUESTS - 1);
 741     client->nb_requests++;
 742     nbd_update_can_read(client);
 743
 744     req = g_new0(NBDRequest, 1);
 745     nbd_client_get(client);
 746     req->client = client;
 747     return req;
 748 }
 749
 750 static void nbd_request_put(NBDRequest *req)
 751 {
 752     NBDClient *client = req->client;
 753
 754     if (req->data) {
 755         qemu_vfree(req->data);
 756     }
 757     g_free(req);
 758
 759     client->nb_requests--;
 760     nbd_update_can_read(client);
 761     nbd_client_put(client);
 762 }
 763
 764 static void blk_aio_attached(AioContext *ctx, void *opaque)
 765 {
 766     NBDExport *exp = opaque;
 767     NBDClient *client;
 768
 769     TRACE("Export %s: Attaching clients to AIO context %p\n", exp->name, ctx);
 770
 771     exp->ctx = ctx;
 772
 773     QTAILQ_FOREACH(client, &exp->clients, next) {
 774         nbd_set_handlers(client);
 775     }
 776 }
 777
 778 static void blk_aio_detach(void *opaque)
 779 {
 780     NBDExport *exp = opaque;
 781     NBDClient *client;
 782
 783     TRACE("Export %s: Detaching clients from AIO context %p\n", exp->name, exp->ctx);
 784
 785     QTAILQ_FOREACH(client, &exp->clients, next) {
 786         nbd_unset_handlers(client);
 787     }
 788
 789     exp->ctx = NULL;
 790 }
 791
 792 static void nbd_eject_notifier(Notifier *n, void *data)
 793 {
 794     NBDExport *exp = container_of(n, NBDExport, eject_notifier);
 795     nbd_export_close(exp);
 796 }
 797
 798 NBDExport *nbd_export_new(BlockBackend *blk, off_t dev_offset, off_t size,
 799                           uint32_t nbdflags, void (*close)(NBDExport *),
 800                           Error **errp)
 801 {
 802     NBDExport *exp = g_malloc0(sizeof(NBDExport));
 803     exp->refcount = 1;
 804     QTAILQ_INIT(&exp->clients);
 805     exp->blk = blk;
 806     exp->dev_offset = dev_offset;
 807     exp->nbdflags = nbdflags;
 808     exp->size = size < 0 ? blk_getlength(blk) : size;
 809     if (exp->size < 0) {
 810         error_setg_errno(errp, -exp->size,
 811                          "Failed to determine the NBD export's length");
 812         goto fail;
 813     }
 814     exp->size -= exp->size % BDRV_SECTOR_SIZE;
 815
 816     exp->close = close;
 817     exp->ctx = blk_get_aio_context(blk);
 818     blk_ref(blk);
 819     blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
 820
 821     exp->eject_notifier.notify = nbd_eject_notifier;
 822     blk_add_remove_bs_notifier(blk, &exp->eject_notifier);
 823
 824     /*
 825      * NBD exports are used for non-shared storage migration.  Make sure
 826      * that BDRV_O_INACTIVE is cleared and the image is ready for write
 827      * access since the export could be available before migration handover.
 828      */
 829     aio_context_acquire(exp->ctx);
 830     blk_invalidate_cache(blk, NULL);
 831     aio_context_release(exp->ctx);
 832     return exp;
 833
 834 fail:
 835     g_free(exp);
 836     return NULL;
 837 }
 838
 839 NBDExport *nbd_export_find(const char *name)
 840 {
 841     NBDExport *exp;
 842     QTAILQ_FOREACH(exp, &exports, next) {
 843         if (strcmp(name, exp->name) == 0) {
 844             return exp;
 845         }
 846     }
 847
 848     return NULL;
 849 }
 850
 851 void nbd_export_set_name(NBDExport *exp, const char *name)
 852 {
 853     if (exp->name == name) {
 854         return;
 855     }
 856
 857     nbd_export_get(exp);
 858     if (exp->name != NULL) {
 859         g_free(exp->name);
 860         exp->name = NULL;
 861         QTAILQ_REMOVE(&exports, exp, next);
 862         nbd_export_put(exp);
 863     }
 864     if (name != NULL) {
 865         nbd_export_get(exp);
 866         exp->name = g_strdup(name);
 867         QTAILQ_INSERT_TAIL(&exports, exp, next);
 868     }
 869     nbd_export_put(exp);
 870 }
 871
 872 void nbd_export_close(NBDExport *exp)
 873 {
 874     NBDClient *client, *next;
 875
 876     nbd_export_get(exp);
 877     QTAILQ_FOREACH_SAFE(client, &exp->clients, next, next) {
 878         client_close(client);
 879     }
 880     nbd_export_set_name(exp, NULL);
 881     nbd_export_put(exp);
 882 }
 883
 884 void nbd_export_get(NBDExport *exp)
 885 {
 886     assert(exp->refcount > 0);
 887     exp->refcount++;
 888 }
 889
 890 void nbd_export_put(NBDExport *exp)
 891 {
 892     assert(exp->refcount > 0);
 893     if (exp->refcount == 1) {
 894         nbd_export_close(exp);
 895     }
 896
 897     if (--exp->refcount == 0) {
 898         assert(exp->name == NULL);
 899
 900         if (exp->close) {
 901             exp->close(exp);
 902         }
 903
 904         if (exp->blk) {
 905             notifier_remove(&exp->eject_notifier);
 906             blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
 907                                             blk_aio_detach, exp);
 908             blk_unref(exp->blk);
 909             exp->blk = NULL;
 910         }
 911
 912         g_free(exp);
 913     }
 914 }
 915
 916 BlockBackend *nbd_export_get_blockdev(NBDExport *exp)
 917 {
 918     return exp->blk;
 919 }
 920
 921 void nbd_export_close_all(void)
 922 {
 923     NBDExport *exp, *next;
 924
 925     QTAILQ_FOREACH_SAFE(exp, &exports, next, next) {
 926         nbd_export_close(exp);
 927     }
 928 }
 929
 930 static ssize_t nbd_co_send_reply(NBDRequest *req, struct nbd_reply *reply,
 931                                  int len)
 932 {
 933     NBDClient *client = req->client;
 934     ssize_t rc, ret;
 935
 936     g_assert(qemu_in_coroutine());
 937     qemu_co_mutex_lock(&client->send_lock);
 938     client->send_coroutine = qemu_coroutine_self();
 939     nbd_set_handlers(client);
 940
 941     if (!len) {
 942         rc = nbd_send_reply(client->ioc, reply);
 943     } else {
 944         qio_channel_set_cork(client->ioc, true);
 945         rc = nbd_send_reply(client->ioc, reply);
 946         if (rc >= 0) {
 947             ret = write_sync(client->ioc, req->data, len);
 948             if (ret != len) {
 949                 rc = -EIO;
 950             }
 951         }
 952         qio_channel_set_cork(client->ioc, false);
 953     }
 954
 955     client->send_coroutine = NULL;
 956     nbd_set_handlers(client);
 957     qemu_co_mutex_unlock(&client->send_lock);
 958     return rc;
 959 }
 960
 961 static ssize_t nbd_co_receive_request(NBDRequest *req, struct nbd_request *request)
 962 {
 963     NBDClient *client = req->client;
 964     uint32_t command;
 965     ssize_t rc;
 966
 967     g_assert(qemu_in_coroutine());
 968     client->recv_coroutine = qemu_coroutine_self();
 969     nbd_update_can_read(client);
 970
 971     rc = nbd_receive_request(client->ioc, request);
 972     if (rc < 0) {
 973         if (rc != -EAGAIN) {
 974             rc = -EIO;
 975         }
 976         goto out;
 977     }
 978
 979     if ((request->from + request->len) < request->from) {
 980         LOG("integer overflow detected! "
 981             "you're probably being attacked");
 982         rc = -EINVAL;
 983         goto out;
 984     }
 985
 986     TRACE("Decoding type");
 987
 988     command = request->type & NBD_CMD_MASK_COMMAND;
 989     if (command == NBD_CMD_READ || command == NBD_CMD_WRITE) {
 990         if (request->len > NBD_MAX_BUFFER_SIZE) {
 991             LOG("len (%u) is larger than max len (%u)",
 992                 request->len, NBD_MAX_BUFFER_SIZE);
 993             rc = -EINVAL;
 994             goto out;
 995         }
 996
 997         req->data = blk_try_blockalign(client->exp->blk, request->len);
 998         if (req->data == NULL) {
 999             rc = -ENOMEM;
1000             goto out;
1001         }
1002     }
1003     if (command == NBD_CMD_WRITE) {
1004         TRACE("Reading %u byte(s)", request->len);
1005
1006         if (read_sync(client->ioc, req->data, request->len) != request->len) {
1007             LOG("reading from socket failed");
1008             rc = -EIO;
1009             goto out;
1010         }
1011     }
1012     rc = 0;
1013
1014 out:
1015     client->recv_coroutine = NULL;
1016     nbd_update_can_read(client);
1017
1018     return rc;
1019 }
1020
1021 static void nbd_trip(void *opaque)
1022 {
1023     NBDClient *client = opaque;
1024     NBDExport *exp = client->exp;
1025     NBDRequest *req;
1026     struct nbd_request request;
1027     struct nbd_reply reply;
1028     ssize_t ret;
1029     uint32_t command;
1030
1031     TRACE("Reading request.");
1032     if (client->closing) {
1033         return;
1034     }
1035
1036     req = nbd_request_get(client);
1037     ret = nbd_co_receive_request(req, &request);
1038     if (ret == -EAGAIN) {
1039         goto done;
1040     }
1041     if (ret == -EIO) {
1042         goto out;
1043     }
1044
1045     reply.handle = request.handle;
1046     reply.error = 0;
1047
1048     if (ret < 0) {
1049         reply.error = -ret;
1050         goto error_reply;
1051     }
1052     command = request.type & NBD_CMD_MASK_COMMAND;
1053     if (command != NBD_CMD_DISC && (request.from + request.len) > exp->size) {
1054             LOG("From: %" PRIu64 ", Len: %u, Size: %" PRIu64
1055             ", Offset: %" PRIu64 "\n",
1056                     request.from, request.len,
1057                     (uint64_t)exp->size, (uint64_t)exp->dev_offset);
1058         LOG("requested operation past EOF--bad client?");
1059         goto invalid_request;
1060     }
1061
1062     if (client->closing) {
1063         /*
1064          * The client may be closed when we are blocked in
1065          * nbd_co_receive_request()
1066          */
1067         goto done;
1068     }
1069
1070     switch (command) {
1071     case NBD_CMD_READ:
1072         TRACE("Request type is READ");
1073
1074         if (request.type & NBD_CMD_FLAG_FUA) {
1075             ret = blk_co_flush(exp->blk);
1076             if (ret < 0) {
1077                 LOG("flush failed");
1078                 reply.error = -ret;
1079                 goto error_reply;
1080             }
1081         }
1082
1083         ret = blk_read(exp->blk,
1084                        (request.from + exp->dev_offset) / BDRV_SECTOR_SIZE,
1085                        req->data, request.len / BDRV_SECTOR_SIZE);
1086         if (ret < 0) {
1087             LOG("reading from file failed");
1088             reply.error = -ret;
1089             goto error_reply;
1090         }
1091
1092         TRACE("Read %u byte(s)", request.len);
1093         if (nbd_co_send_reply(req, &reply, request.len) < 0)
1094             goto out;
1095         break;
1096     case NBD_CMD_WRITE:
1097         TRACE("Request type is WRITE");
1098
1099         if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
1100             TRACE("Server is read-only, return error");
1101             reply.error = EROFS;
1102             goto error_reply;
1103         }
1104
1105         TRACE("Writing to device");
1106
1107         ret = blk_write(exp->blk,
1108                         (request.from + exp->dev_offset) / BDRV_SECTOR_SIZE,
1109                         req->data, request.len / BDRV_SECTOR_SIZE);
1110         if (ret < 0) {
1111             LOG("writing to file failed");
1112             reply.error = -ret;
1113             goto error_reply;
1114         }
1115
1116         if (request.type & NBD_CMD_FLAG_FUA) {
1117             ret = blk_co_flush(exp->blk);
1118             if (ret < 0) {
1119                 LOG("flush failed");
1120                 reply.error = -ret;
1121                 goto error_reply;
1122             }
1123         }
1124
1125         if (nbd_co_send_reply(req, &reply, 0) < 0) {
1126             goto out;
1127         }
1128         break;
1129     case NBD_CMD_DISC:
1130         TRACE("Request type is DISCONNECT");
1131         errno = 0;
1132         goto out;
1133     case NBD_CMD_FLUSH:
1134         TRACE("Request type is FLUSH");
1135
1136         ret = blk_co_flush(exp->blk);
1137         if (ret < 0) {
1138             LOG("flush failed");
1139             reply.error = -ret;
1140         }
1141         if (nbd_co_send_reply(req, &reply, 0) < 0) {
1142             goto out;
1143         }
1144         break;
1145     case NBD_CMD_TRIM:
1146         TRACE("Request type is TRIM");
1147         ret = blk_co_discard(exp->blk, (request.from + exp->dev_offset)
1148                                        / BDRV_SECTOR_SIZE,
1149                              request.len / BDRV_SECTOR_SIZE);
1150         if (ret < 0) {
1151             LOG("discard failed");
1152             reply.error = -ret;
1153         }
1154         if (nbd_co_send_reply(req, &reply, 0) < 0) {
1155             goto out;
1156         }
1157         break;
1158     default:
1159         LOG("invalid request type (%u) received", request.type);
1160     invalid_request:
1161         reply.error = EINVAL;
1162     error_reply:
1163         if (nbd_co_send_reply(req, &reply, 0) < 0) {
1164             goto out;
1165         }
1166         break;
1167     }
1168
1169     TRACE("Request/Reply complete");
1170
1171 done:
1172     nbd_request_put(req);
1173     return;
1174
1175 out:
1176     nbd_request_put(req);
1177     client_close(client);
1178 }
1179
1180 static void nbd_read(void *opaque)
1181 {
1182     NBDClient *client = opaque;
1183
1184     if (client->recv_coroutine) {
1185         qemu_coroutine_enter(client->recv_coroutine, NULL);
1186     } else {
1187         qemu_coroutine_enter(qemu_coroutine_create(nbd_trip), client);
1188     }
1189 }
1190
1191 static void nbd_restart_write(void *opaque)
1192 {
1193     NBDClient *client = opaque;
1194
1195     qemu_coroutine_enter(client->send_coroutine, NULL);
1196 }
1197
1198 static void nbd_set_handlers(NBDClient *client)
1199 {
1200     if (client->exp && client->exp->ctx) {
1201         aio_set_fd_handler(client->exp->ctx, client->sioc->fd,
1202                            true,
1203                            client->can_read ? nbd_read : NULL,
1204                            client->send_coroutine ? nbd_restart_write : NULL,
1205                            client);
1206     }
1207 }
1208
1209 static void nbd_unset_handlers(NBDClient *client)
1210 {
1211     if (client->exp && client->exp->ctx) {
1212         aio_set_fd_handler(client->exp->ctx, client->sioc->fd,
1213                            true, NULL, NULL, NULL);
1214     }
1215 }
1216
1217 static void nbd_update_can_read(NBDClient *client)
1218 {
1219     bool can_read = client->recv_coroutine ||
1220                     client->nb_requests < MAX_NBD_REQUESTS;
1221
1222     if (can_read != client->can_read) {
1223         client->can_read = can_read;
1224         nbd_set_handlers(client);
1225
1226         /* There is no need to invoke aio_notify(), since aio_set_fd_handler()
1227          * in nbd_set_handlers() will have taken care of that */
1228     }
1229 }
1230
1231 static coroutine_fn void nbd_co_client_start(void *opaque)
1232 {
1233     NBDClientNewData *data = opaque;
1234     NBDClient *client = data->client;
1235     NBDExport *exp = client->exp;
1236
1237     if (exp) {
1238         nbd_export_get(exp);
1239     }
1240     if (nbd_negotiate(data)) {
1241         client_close(client);
1242         goto out;
1243     }
1244     qemu_co_mutex_init(&client->send_lock);
1245     nbd_set_handlers(client);
1246
1247     if (exp) {
1248         QTAILQ_INSERT_TAIL(&exp->clients, client, next);
1249     }
1250 out:
1251     g_free(data);
1252 }
1253
1254 void nbd_client_new(NBDExport *exp,
1255                     QIOChannelSocket *sioc,
1256                     QCryptoTLSCreds *tlscreds,
1257                     const char *tlsaclname,
1258                     void (*close_fn)(NBDClient *))
1259 {
1260     NBDClient *client;
1261     NBDClientNewData *data = g_new(NBDClientNewData, 1);
1262
1263     client = g_malloc0(sizeof(NBDClient));
1264     client->refcount = 1;
1265     client->exp = exp;
1266     client->tlscreds = tlscreds;
1267     if (tlscreds) {
1268         object_ref(OBJECT(client->tlscreds));
1269     }
1270     client->tlsaclname = g_strdup(tlsaclname);
1271     client->sioc = sioc;
1272     object_ref(OBJECT(client->sioc));
1273     client->ioc = QIO_CHANNEL(sioc);
1274     object_ref(OBJECT(client->ioc));
1275     client->can_read = true;
1276     client->close = close_fn;
1277
1278     data->client = client;
1279     data->co = qemu_coroutine_create(nbd_co_client_start);
1280     qemu_coroutine_enter(data->co, data);
1281 }