nbd/server.c

   1 /*
   2  *  Copyright (C) 2016 Red Hat, Inc.
   3  *  Copyright (C) 2005  Anthony Liguori <anthony@codemonkey.ws>
   4  *
   5  *  Network Block Device Server Side
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License as published by
   9  *  the Free Software Foundation; under version 2 of the License.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include "qemu/osdep.h"
  21 #include "qapi/error.h"
  22 #include "nbd-internal.h"
  23
  24 static int system_errno_to_nbd_errno(int err)
  25 {
  26     switch (err) {
  27     case 0:
  28         return NBD_SUCCESS;
  29     case EPERM:
  30     case EROFS:
  31         return NBD_EPERM;
  32     case EIO:
  33         return NBD_EIO;
  34     case ENOMEM:
  35         return NBD_ENOMEM;
  36 #ifdef EDQUOT
  37     case EDQUOT:
  38 #endif
  39     case EFBIG:
  40     case ENOSPC:
  41         return NBD_ENOSPC;
  42     case ESHUTDOWN:
  43         return NBD_ESHUTDOWN;
  44     case EINVAL:
  45     default:
  46         return NBD_EINVAL;
  47     }
  48 }
  49
  50 /* Definitions for opaque data types */
  51
  52 typedef struct NBDRequestData NBDRequestData;
  53
  54 struct NBDRequestData {
  55     QSIMPLEQ_ENTRY(NBDRequestData) entry;
  56     NBDClient *client;
  57     uint8_t *data;
  58     bool complete;
  59 };
  60
  61 struct NBDExport {
  62     int refcount;
  63     void (*close)(NBDExport *exp);
  64
  65     BlockBackend *blk;
  66     char *name;
  67     char *description;
  68     off_t dev_offset;
  69     off_t size;
  70     uint16_t nbdflags;
  71     QTAILQ_HEAD(, NBDClient) clients;
  72     QTAILQ_ENTRY(NBDExport) next;
  73
  74     AioContext *ctx;
  75
  76     BlockBackend *eject_notifier_blk;
  77     Notifier eject_notifier;
  78 };
  79
  80 static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
  81
  82 struct NBDClient {
  83     int refcount;
  84     void (*close_fn)(NBDClient *client, bool negotiated);
  85
  86     bool no_zeroes;
  87     NBDExport *exp;
  88     QCryptoTLSCreds *tlscreds;
  89     char *tlsaclname;
  90     QIOChannelSocket *sioc; /* The underlying data channel */
  91     QIOChannel *ioc; /* The current I/O channel which may differ (eg TLS) */
  92
  93     Coroutine *recv_coroutine;
  94
  95     CoMutex send_lock;
  96     Coroutine *send_coroutine;
  97
  98     QTAILQ_ENTRY(NBDClient) next;
  99     int nb_requests;
 100     bool closing;
 101 };
 102
 103 /* That's all folks */
 104
 105 static void nbd_client_receive_next_request(NBDClient *client);
 106
 107 /* Basic flow for negotiation
 108
 109    Server         Client
 110    Negotiate
 111
 112    or
 113
 114    Server         Client
 115    Negotiate #1
 116                   Option
 117    Negotiate #2
 118
 119    ----
 120
 121    followed by
 122
 123    Server         Client
 124                   Request
 125    Response
 126                   Request
 127    Response
 128                   ...
 129    ...
 130                   Request (type == 2)
 131
 132 */
 133
 134 /* Send a reply header, including length, but no payload.
 135  * Return -errno on error, 0 on success. */
 136 static int nbd_negotiate_send_rep_len(QIOChannel *ioc, uint32_t type,
 137                                       uint32_t opt, uint32_t len)
 138 {
 139     uint64_t magic;
 140
 141     TRACE("Reply opt=%" PRIx32 " type=%" PRIx32 " len=%" PRIu32,
 142           type, opt, len);
 143
 144     magic = cpu_to_be64(NBD_REP_MAGIC);
 145     if (nbd_write(ioc, &magic, sizeof(magic), NULL) < 0) {
 146         LOG("write failed (rep magic)");
 147         return -EINVAL;
 148     }
 149     opt = cpu_to_be32(opt);
 150     if (nbd_write(ioc, &opt, sizeof(opt), NULL) < 0) {
 151         LOG("write failed (rep opt)");
 152         return -EINVAL;
 153     }
 154     type = cpu_to_be32(type);
 155     if (nbd_write(ioc, &type, sizeof(type), NULL) < 0) {
 156         LOG("write failed (rep type)");
 157         return -EINVAL;
 158     }
 159     len = cpu_to_be32(len);
 160     if (nbd_write(ioc, &len, sizeof(len), NULL) < 0) {
 161         LOG("write failed (rep data length)");
 162         return -EINVAL;
 163     }
 164     return 0;
 165 }
 166
 167 /* Send a reply header with default 0 length.
 168  * Return -errno on error, 0 on success. */
 169 static int nbd_negotiate_send_rep(QIOChannel *ioc, uint32_t type, uint32_t opt)
 170 {
 171     return nbd_negotiate_send_rep_len(ioc, type, opt, 0);
 172 }
 173
 174 /* Send an error reply.
 175  * Return -errno on error, 0 on success. */
 176 static int GCC_FMT_ATTR(4, 5)
 177 nbd_negotiate_send_rep_err(QIOChannel *ioc, uint32_t type,
 178                            uint32_t opt, const char *fmt, ...)
 179 {
 180     va_list va;
 181     char *msg;
 182     int ret;
 183     size_t len;
 184
 185     va_start(va, fmt);
 186     msg = g_strdup_vprintf(fmt, va);
 187     va_end(va);
 188     len = strlen(msg);
 189     assert(len < 4096);
 190     TRACE("sending error message \"%s\"", msg);
 191     ret = nbd_negotiate_send_rep_len(ioc, type, opt, len);
 192     if (ret < 0) {
 193         goto out;
 194     }
 195     if (nbd_write(ioc, msg, len, NULL) < 0) {
 196         LOG("write failed (error message)");
 197         ret = -EIO;
 198     } else {
 199         ret = 0;
 200     }
 201 out:
 202     g_free(msg);
 203     return ret;
 204 }
 205
 206 /* Send a single NBD_REP_SERVER reply to NBD_OPT_LIST, including payload.
 207  * Return -errno on error, 0 on success. */
 208 static int nbd_negotiate_send_rep_list(QIOChannel *ioc, NBDExport *exp)
 209 {
 210     size_t name_len, desc_len;
 211     uint32_t len;
 212     const char *name = exp->name ? exp->name : "";
 213     const char *desc = exp->description ? exp->description : "";
 214     int ret;
 215
 216     TRACE("Advertising export name '%s' description '%s'", name, desc);
 217     name_len = strlen(name);
 218     desc_len = strlen(desc);
 219     len = name_len + desc_len + sizeof(len);
 220     ret = nbd_negotiate_send_rep_len(ioc, NBD_REP_SERVER, NBD_OPT_LIST, len);
 221     if (ret < 0) {
 222         return ret;
 223     }
 224
 225     len = cpu_to_be32(name_len);
 226     if (nbd_write(ioc, &len, sizeof(len), NULL) < 0) {
 227         LOG("write failed (name length)");
 228         return -EINVAL;
 229     }
 230     if (nbd_write(ioc, name, name_len, NULL) < 0) {
 231         LOG("write failed (name buffer)");
 232         return -EINVAL;
 233     }
 234     if (nbd_write(ioc, desc, desc_len, NULL) < 0) {
 235         LOG("write failed (description buffer)");
 236         return -EINVAL;
 237     }
 238     return 0;
 239 }
 240
 241 /* Process the NBD_OPT_LIST command, with a potential series of replies.
 242  * Return -errno on error, 0 on success. */
 243 static int nbd_negotiate_handle_list(NBDClient *client, uint32_t length)
 244 {
 245     NBDExport *exp;
 246
 247     if (length) {
 248         if (nbd_drop(client->ioc, length, NULL) < 0) {
 249             return -EIO;
 250         }
 251         return nbd_negotiate_send_rep_err(client->ioc,
 252                                           NBD_REP_ERR_INVALID, NBD_OPT_LIST,
 253                                           "OPT_LIST should not have length");
 254     }
 255
 256     /* For each export, send a NBD_REP_SERVER reply. */
 257     QTAILQ_FOREACH(exp, &exports, next) {
 258         if (nbd_negotiate_send_rep_list(client->ioc, exp)) {
 259             return -EINVAL;
 260         }
 261     }
 262     /* Finish with a NBD_REP_ACK. */
 263     return nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, NBD_OPT_LIST);
 264 }
 265
 266 static int nbd_negotiate_handle_export_name(NBDClient *client, uint32_t length)
 267 {
 268     char name[NBD_MAX_NAME_SIZE + 1];
 269
 270     /* Client sends:
 271         [20 ..  xx]   export name (length bytes)
 272      */
 273     TRACE("Checking length");
 274     if (length >= sizeof(name)) {
 275         LOG("Bad length received");
 276         return -EINVAL;
 277     }
 278     if (nbd_read(client->ioc, name, length, NULL) < 0) {
 279         LOG("read failed");
 280         return -EINVAL;
 281     }
 282     name[length] = '\0';
 283
 284     TRACE("Client requested export '%s'", name);
 285
 286     client->exp = nbd_export_find(name);
 287     if (!client->exp) {
 288         LOG("export not found");
 289         return -EINVAL;
 290     }
 291
 292     QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
 293     nbd_export_get(client->exp);
 294
 295     return 0;
 296 }
 297
 298 /* Handle NBD_OPT_STARTTLS. Return NULL to drop connection, or else the
 299  * new channel for all further (now-encrypted) communication. */
 300 static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client,
 301                                                  uint32_t length)
 302 {
 303     QIOChannel *ioc;
 304     QIOChannelTLS *tioc;
 305     struct NBDTLSHandshakeData data = { 0 };
 306
 307     TRACE("Setting up TLS");
 308     ioc = client->ioc;
 309     if (length) {
 310         if (nbd_drop(ioc, length, NULL) < 0) {
 311             return NULL;
 312         }
 313         nbd_negotiate_send_rep_err(ioc, NBD_REP_ERR_INVALID, NBD_OPT_STARTTLS,
 314                                    "OPT_STARTTLS should not have length");
 315         return NULL;
 316     }
 317
 318     if (nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK,
 319                                NBD_OPT_STARTTLS) < 0) {
 320         return NULL;
 321     }
 322
 323     tioc = qio_channel_tls_new_server(ioc,
 324                                       client->tlscreds,
 325                                       client->tlsaclname,
 326                                       NULL);
 327     if (!tioc) {
 328         return NULL;
 329     }
 330
 331     qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-server-tls");
 332     TRACE("Starting TLS handshake");
 333     data.loop = g_main_loop_new(g_main_context_default(), FALSE);
 334     qio_channel_tls_handshake(tioc,
 335                               nbd_tls_handshake,
 336                               &data,
 337                               NULL);
 338
 339     if (!data.complete) {
 340         g_main_loop_run(data.loop);
 341     }
 342     g_main_loop_unref(data.loop);
 343     if (data.error) {
 344         object_unref(OBJECT(tioc));
 345         error_free(data.error);
 346         return NULL;
 347     }
 348
 349     return QIO_CHANNEL(tioc);
 350 }
 351
 352
 353 /* Process all NBD_OPT_* client option commands.
 354  * Return -errno on error, 0 on success. */
 355 static int nbd_negotiate_options(NBDClient *client)
 356 {
 357     uint32_t flags;
 358     bool fixedNewstyle = false;
 359
 360     /* Client sends:
 361         [ 0 ..   3]   client flags
 362
 363         [ 0 ..   7]   NBD_OPTS_MAGIC
 364         [ 8 ..  11]   NBD option
 365         [12 ..  15]   Data length
 366         ...           Rest of request
 367
 368         [ 0 ..   7]   NBD_OPTS_MAGIC
 369         [ 8 ..  11]   Second NBD option
 370         [12 ..  15]   Data length
 371         ...           Rest of request
 372     */
 373
 374     if (nbd_read(client->ioc, &flags, sizeof(flags), NULL) < 0) {
 375         LOG("read failed");
 376         return -EIO;
 377     }
 378     TRACE("Checking client flags");
 379     be32_to_cpus(&flags);
 380     if (flags & NBD_FLAG_C_FIXED_NEWSTYLE) {
 381         TRACE("Client supports fixed newstyle handshake");
 382         fixedNewstyle = true;
 383         flags &= ~NBD_FLAG_C_FIXED_NEWSTYLE;
 384     }
 385     if (flags & NBD_FLAG_C_NO_ZEROES) {
 386         TRACE("Client supports no zeroes at handshake end");
 387         client->no_zeroes = true;
 388         flags &= ~NBD_FLAG_C_NO_ZEROES;
 389     }
 390     if (flags != 0) {
 391         TRACE("Unknown client flags 0x%" PRIx32 " received", flags);
 392         return -EIO;
 393     }
 394
 395     while (1) {
 396         int ret;
 397         uint32_t clientflags, length;
 398         uint64_t magic;
 399
 400         if (nbd_read(client->ioc, &magic, sizeof(magic), NULL) < 0) {
 401             LOG("read failed");
 402             return -EINVAL;
 403         }
 404         TRACE("Checking opts magic");
 405         if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) {
 406             LOG("Bad magic received");
 407             return -EINVAL;
 408         }
 409
 410         if (nbd_read(client->ioc, &clientflags,
 411                       sizeof(clientflags), NULL) < 0)
 412         {
 413             LOG("read failed");
 414             return -EINVAL;
 415         }
 416         clientflags = be32_to_cpu(clientflags);
 417
 418         if (nbd_read(client->ioc, &length, sizeof(length), NULL) < 0) {
 419             LOG("read failed");
 420             return -EINVAL;
 421         }
 422         length = be32_to_cpu(length);
 423
 424         TRACE("Checking option 0x%" PRIx32, clientflags);
 425         if (client->tlscreds &&
 426             client->ioc == (QIOChannel *)client->sioc) {
 427             QIOChannel *tioc;
 428             if (!fixedNewstyle) {
 429                 TRACE("Unsupported option 0x%" PRIx32, clientflags);
 430                 return -EINVAL;
 431             }
 432             switch (clientflags) {
 433             case NBD_OPT_STARTTLS:
 434                 tioc = nbd_negotiate_handle_starttls(client, length);
 435                 if (!tioc) {
 436                     return -EIO;
 437                 }
 438                 object_unref(OBJECT(client->ioc));
 439                 client->ioc = QIO_CHANNEL(tioc);
 440                 break;
 441
 442             case NBD_OPT_EXPORT_NAME:
 443                 /* No way to return an error to client, so drop connection */
 444                 TRACE("Option 0x%x not permitted before TLS", clientflags);
 445                 return -EINVAL;
 446
 447             default:
 448                 if (nbd_drop(client->ioc, length, NULL) < 0) {
 449                     return -EIO;
 450                 }
 451                 ret = nbd_negotiate_send_rep_err(client->ioc,
 452                                                  NBD_REP_ERR_TLS_REQD,
 453                                                  clientflags,
 454                                                  "Option 0x%" PRIx32
 455                                                  "not permitted before TLS",
 456                                                  clientflags);
 457                 if (ret < 0) {
 458                     return ret;
 459                 }
 460                 /* Let the client keep trying, unless they asked to quit */
 461                 if (clientflags == NBD_OPT_ABORT) {
 462                     return -EINVAL;
 463                 }
 464                 break;
 465             }
 466         } else if (fixedNewstyle) {
 467             switch (clientflags) {
 468             case NBD_OPT_LIST:
 469                 ret = nbd_negotiate_handle_list(client, length);
 470                 if (ret < 0) {
 471                     return ret;
 472                 }
 473                 break;
 474
 475             case NBD_OPT_ABORT:
 476                 /* NBD spec says we must try to reply before
 477                  * disconnecting, but that we must also tolerate
 478                  * guests that don't wait for our reply. */
 479                 nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, clientflags);
 480                 return -EINVAL;
 481
 482             case NBD_OPT_EXPORT_NAME:
 483                 return nbd_negotiate_handle_export_name(client, length);
 484
 485             case NBD_OPT_STARTTLS:
 486                 if (nbd_drop(client->ioc, length, NULL) < 0) {
 487                     return -EIO;
 488                 }
 489                 if (client->tlscreds) {
 490                     ret = nbd_negotiate_send_rep_err(client->ioc,
 491                                                      NBD_REP_ERR_INVALID,
 492                                                      clientflags,
 493                                                      "TLS already enabled");
 494                 } else {
 495                     ret = nbd_negotiate_send_rep_err(client->ioc,
 496                                                      NBD_REP_ERR_POLICY,
 497                                                      clientflags,
 498                                                      "TLS not configured");
 499                 }
 500                 if (ret < 0) {
 501                     return ret;
 502                 }
 503                 break;
 504             default:
 505                 if (nbd_drop(client->ioc, length, NULL) < 0) {
 506                     return -EIO;
 507                 }
 508                 ret = nbd_negotiate_send_rep_err(client->ioc,
 509                                                  NBD_REP_ERR_UNSUP,
 510                                                  clientflags,
 511                                                  "Unsupported option 0x%"
 512                                                  PRIx32,
 513                                                  clientflags);
 514                 if (ret < 0) {
 515                     return ret;
 516                 }
 517                 break;
 518             }
 519         } else {
 520             /*
 521              * If broken new-style we should drop the connection
 522              * for anything except NBD_OPT_EXPORT_NAME
 523              */
 524             switch (clientflags) {
 525             case NBD_OPT_EXPORT_NAME:
 526                 return nbd_negotiate_handle_export_name(client, length);
 527
 528             default:
 529                 TRACE("Unsupported option 0x%" PRIx32, clientflags);
 530                 return -EINVAL;
 531             }
 532         }
 533     }
 534 }
 535
 536 static coroutine_fn int nbd_negotiate(NBDClient *client)
 537 {
 538     char buf[8 + 8 + 8 + 128];
 539     int ret;
 540     const uint16_t myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM |
 541                               NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA |
 542                               NBD_FLAG_SEND_WRITE_ZEROES);
 543     bool oldStyle;
 544     size_t len;
 545
 546     /* Old style negotiation header without options
 547         [ 0 ..   7]   passwd       ("NBDMAGIC")
 548         [ 8 ..  15]   magic        (NBD_CLIENT_MAGIC)
 549         [16 ..  23]   size
 550         [24 ..  25]   server flags (0)
 551         [26 ..  27]   export flags
 552         [28 .. 151]   reserved     (0)
 553
 554        New style negotiation header with options
 555         [ 0 ..   7]   passwd       ("NBDMAGIC")
 556         [ 8 ..  15]   magic        (NBD_OPTS_MAGIC)
 557         [16 ..  17]   server flags (0)
 558         ....options sent....
 559         [18 ..  25]   size
 560         [26 ..  27]   export flags
 561         [28 .. 151]   reserved     (0, omit if no_zeroes)
 562      */
 563
 564     qio_channel_set_blocking(client->ioc, false, NULL);
 565
 566     TRACE("Beginning negotiation.");
 567     memset(buf, 0, sizeof(buf));
 568     memcpy(buf, "NBDMAGIC", 8);
 569
 570     oldStyle = client->exp != NULL && !client->tlscreds;
 571     if (oldStyle) {
 572         TRACE("advertising size %" PRIu64 " and flags %x",
 573               client->exp->size, client->exp->nbdflags | myflags);
 574         stq_be_p(buf + 8, NBD_CLIENT_MAGIC);
 575         stq_be_p(buf + 16, client->exp->size);
 576         stw_be_p(buf + 26, client->exp->nbdflags | myflags);
 577     } else {
 578         stq_be_p(buf + 8, NBD_OPTS_MAGIC);
 579         stw_be_p(buf + 16, NBD_FLAG_FIXED_NEWSTYLE | NBD_FLAG_NO_ZEROES);
 580     }
 581
 582     if (oldStyle) {
 583         if (client->tlscreds) {
 584             TRACE("TLS cannot be enabled with oldstyle protocol");
 585             return -EINVAL;
 586         }
 587         if (nbd_write(client->ioc, buf, sizeof(buf), NULL) < 0) {
 588             LOG("write failed");
 589             return -EINVAL;
 590         }
 591     } else {
 592         if (nbd_write(client->ioc, buf, 18, NULL) < 0) {
 593             LOG("write failed");
 594             return -EINVAL;
 595         }
 596         ret = nbd_negotiate_options(client);
 597         if (ret != 0) {
 598             LOG("option negotiation failed");
 599             return ret;
 600         }
 601
 602         TRACE("advertising size %" PRIu64 " and flags %x",
 603               client->exp->size, client->exp->nbdflags | myflags);
 604         stq_be_p(buf + 18, client->exp->size);
 605         stw_be_p(buf + 26, client->exp->nbdflags | myflags);
 606         len = client->no_zeroes ? 10 : sizeof(buf) - 18;
 607         ret = nbd_write(client->ioc, buf + 18, len, NULL);
 608         if (ret < 0) {
 609             LOG("write failed");
 610             return ret;
 611         }
 612     }
 613
 614     TRACE("Negotiation succeeded.");
 615
 616     return 0;
 617 }
 618
 619 static int nbd_receive_request(QIOChannel *ioc, NBDRequest *request)
 620 {
 621     uint8_t buf[NBD_REQUEST_SIZE];
 622     uint32_t magic;
 623     int ret;
 624
 625     ret = nbd_read(ioc, buf, sizeof(buf), NULL);
 626     if (ret < 0) {
 627         return ret;
 628     }
 629
 630     /* Request
 631        [ 0 ..  3]   magic   (NBD_REQUEST_MAGIC)
 632        [ 4 ..  5]   flags   (NBD_CMD_FLAG_FUA, ...)
 633        [ 6 ..  7]   type    (NBD_CMD_READ, ...)
 634        [ 8 .. 15]   handle
 635        [16 .. 23]   from
 636        [24 .. 27]   len
 637      */
 638
 639     magic = ldl_be_p(buf);
 640     request->flags  = lduw_be_p(buf + 4);
 641     request->type   = lduw_be_p(buf + 6);
 642     request->handle = ldq_be_p(buf + 8);
 643     request->from   = ldq_be_p(buf + 16);
 644     request->len    = ldl_be_p(buf + 24);
 645
 646     TRACE("Got request: { magic = 0x%" PRIx32 ", .flags = %" PRIx16
 647           ", .type = %" PRIx16 ", from = %" PRIu64 ", len = %" PRIu32 " }",
 648           magic, request->flags, request->type, request->from, request->len);
 649
 650     if (magic != NBD_REQUEST_MAGIC) {
 651         LOG("invalid magic (got 0x%" PRIx32 ")", magic);
 652         return -EINVAL;
 653     }
 654     return 0;
 655 }
 656
 657 static int nbd_send_reply(QIOChannel *ioc, NBDReply *reply)
 658 {
 659     uint8_t buf[NBD_REPLY_SIZE];
 660
 661     reply->error = system_errno_to_nbd_errno(reply->error);
 662
 663     TRACE("Sending response to client: { .error = %" PRId32
 664           ", handle = %" PRIu64 " }",
 665           reply->error, reply->handle);
 666
 667     /* Reply
 668        [ 0 ..  3]    magic   (NBD_REPLY_MAGIC)
 669        [ 4 ..  7]    error   (0 == no error)
 670        [ 7 .. 15]    handle
 671      */
 672     stl_be_p(buf, NBD_REPLY_MAGIC);
 673     stl_be_p(buf + 4, reply->error);
 674     stq_be_p(buf + 8, reply->handle);
 675
 676     return nbd_write(ioc, buf, sizeof(buf), NULL);
 677 }
 678
 679 #define MAX_NBD_REQUESTS 16
 680
 681 void nbd_client_get(NBDClient *client)
 682 {
 683     client->refcount++;
 684 }
 685
 686 void nbd_client_put(NBDClient *client)
 687 {
 688     if (--client->refcount == 0) {
 689         /* The last reference should be dropped by client->close,
 690          * which is called by client_close.
 691          */
 692         assert(client->closing);
 693
 694         qio_channel_detach_aio_context(client->ioc);
 695         object_unref(OBJECT(client->sioc));
 696         object_unref(OBJECT(client->ioc));
 697         if (client->tlscreds) {
 698             object_unref(OBJECT(client->tlscreds));
 699         }
 700         g_free(client->tlsaclname);
 701         if (client->exp) {
 702             QTAILQ_REMOVE(&client->exp->clients, client, next);
 703             nbd_export_put(client->exp);
 704         }
 705         g_free(client);
 706     }
 707 }
 708
 709 static void client_close(NBDClient *client, bool negotiated)
 710 {
 711     if (client->closing) {
 712         return;
 713     }
 714
 715     client->closing = true;
 716
 717     /* Force requests to finish.  They will drop their own references,
 718      * then we'll close the socket and free the NBDClient.
 719      */
 720     qio_channel_shutdown(client->ioc, QIO_CHANNEL_SHUTDOWN_BOTH,
 721                          NULL);
 722
 723     /* Also tell the client, so that they release their reference.  */
 724     if (client->close_fn) {
 725         client->close_fn(client, negotiated);
 726     }
 727 }
 728
 729 static NBDRequestData *nbd_request_get(NBDClient *client)
 730 {
 731     NBDRequestData *req;
 732
 733     assert(client->nb_requests <= MAX_NBD_REQUESTS - 1);
 734     client->nb_requests++;
 735
 736     req = g_new0(NBDRequestData, 1);
 737     nbd_client_get(client);
 738     req->client = client;
 739     return req;
 740 }
 741
 742 static void nbd_request_put(NBDRequestData *req)
 743 {
 744     NBDClient *client = req->client;
 745
 746     if (req->data) {
 747         qemu_vfree(req->data);
 748     }
 749     g_free(req);
 750
 751     client->nb_requests--;
 752     nbd_client_receive_next_request(client);
 753
 754     nbd_client_put(client);
 755 }
 756
 757 static void blk_aio_attached(AioContext *ctx, void *opaque)
 758 {
 759     NBDExport *exp = opaque;
 760     NBDClient *client;
 761
 762     TRACE("Export %s: Attaching clients to AIO context %p\n", exp->name, ctx);
 763
 764     exp->ctx = ctx;
 765
 766     QTAILQ_FOREACH(client, &exp->clients, next) {
 767         qio_channel_attach_aio_context(client->ioc, ctx);
 768         if (client->recv_coroutine) {
 769             aio_co_schedule(ctx, client->recv_coroutine);
 770         }
 771         if (client->send_coroutine) {
 772             aio_co_schedule(ctx, client->send_coroutine);
 773         }
 774     }
 775 }
 776
 777 static void blk_aio_detach(void *opaque)
 778 {
 779     NBDExport *exp = opaque;
 780     NBDClient *client;
 781
 782     TRACE("Export %s: Detaching clients from AIO context %p\n", exp->name, exp->ctx);
 783
 784     QTAILQ_FOREACH(client, &exp->clients, next) {
 785         qio_channel_detach_aio_context(client->ioc);
 786     }
 787
 788     exp->ctx = NULL;
 789 }
 790
 791 static void nbd_eject_notifier(Notifier *n, void *data)
 792 {
 793     NBDExport *exp = container_of(n, NBDExport, eject_notifier);
 794     nbd_export_close(exp);
 795 }
 796
 797 NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset, off_t size,
 798                           uint16_t nbdflags, void (*close)(NBDExport *),
 799                           bool writethrough, BlockBackend *on_eject_blk,
 800                           Error **errp)
 801 {
 802     BlockBackend *blk;
 803     NBDExport *exp = g_malloc0(sizeof(NBDExport));
 804     uint64_t perm;
 805     int ret;
 806
 807     /* Don't allow resize while the NBD server is running, otherwise we don't
 808      * care what happens with the node. */
 809     perm = BLK_PERM_CONSISTENT_READ;
 810     if ((nbdflags & NBD_FLAG_READ_ONLY) == 0) {
 811         perm |= BLK_PERM_WRITE;
 812     }
 813     blk = blk_new(perm, BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
 814                         BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD);
 815     ret = blk_insert_bs(blk, bs, errp);
 816     if (ret < 0) {
 817         goto fail;
 818     }
 819     blk_set_enable_write_cache(blk, !writethrough);
 820
 821     exp->refcount = 1;
 822     QTAILQ_INIT(&exp->clients);
 823     exp->blk = blk;
 824     exp->dev_offset = dev_offset;
 825     exp->nbdflags = nbdflags;
 826     exp->size = size < 0 ? blk_getlength(blk) : size;
 827     if (exp->size < 0) {
 828         error_setg_errno(errp, -exp->size,
 829                          "Failed to determine the NBD export's length");
 830         goto fail;
 831     }
 832     exp->size -= exp->size % BDRV_SECTOR_SIZE;
 833
 834     exp->close = close;
 835     exp->ctx = blk_get_aio_context(blk);
 836     blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
 837
 838     if (on_eject_blk) {
 839         blk_ref(on_eject_blk);
 840         exp->eject_notifier_blk = on_eject_blk;
 841         exp->eject_notifier.notify = nbd_eject_notifier;
 842         blk_add_remove_bs_notifier(on_eject_blk, &exp->eject_notifier);
 843     }
 844
 845     /*
 846      * NBD exports are used for non-shared storage migration.  Make sure
 847      * that BDRV_O_INACTIVE is cleared and the image is ready for write
 848      * access since the export could be available before migration handover.
 849      */
 850     aio_context_acquire(exp->ctx);
 851     blk_invalidate_cache(blk, NULL);
 852     aio_context_release(exp->ctx);
 853     return exp;
 854
 855 fail:
 856     blk_unref(blk);
 857     g_free(exp);
 858     return NULL;
 859 }
 860
 861 NBDExport *nbd_export_find(const char *name)
 862 {
 863     NBDExport *exp;
 864     QTAILQ_FOREACH(exp, &exports, next) {
 865         if (strcmp(name, exp->name) == 0) {
 866             return exp;
 867         }
 868     }
 869
 870     return NULL;
 871 }
 872
 873 void nbd_export_set_name(NBDExport *exp, const char *name)
 874 {
 875     if (exp->name == name) {
 876         return;
 877     }
 878
 879     nbd_export_get(exp);
 880     if (exp->name != NULL) {
 881         g_free(exp->name);
 882         exp->name = NULL;
 883         QTAILQ_REMOVE(&exports, exp, next);
 884         nbd_export_put(exp);
 885     }
 886     if (name != NULL) {
 887         nbd_export_get(exp);
 888         exp->name = g_strdup(name);
 889         QTAILQ_INSERT_TAIL(&exports, exp, next);
 890     }
 891     nbd_export_put(exp);
 892 }
 893
 894 void nbd_export_set_description(NBDExport *exp, const char *description)
 895 {
 896     g_free(exp->description);
 897     exp->description = g_strdup(description);
 898 }
 899
 900 void nbd_export_close(NBDExport *exp)
 901 {
 902     NBDClient *client, *next;
 903
 904     nbd_export_get(exp);
 905     QTAILQ_FOREACH_SAFE(client, &exp->clients, next, next) {
 906         client_close(client, true);
 907     }
 908     nbd_export_set_name(exp, NULL);
 909     nbd_export_set_description(exp, NULL);
 910     nbd_export_put(exp);
 911 }
 912
 913 void nbd_export_get(NBDExport *exp)
 914 {
 915     assert(exp->refcount > 0);
 916     exp->refcount++;
 917 }
 918
 919 void nbd_export_put(NBDExport *exp)
 920 {
 921     assert(exp->refcount > 0);
 922     if (exp->refcount == 1) {
 923         nbd_export_close(exp);
 924     }
 925
 926     if (--exp->refcount == 0) {
 927         assert(exp->name == NULL);
 928         assert(exp->description == NULL);
 929
 930         if (exp->close) {
 931             exp->close(exp);
 932         }
 933
 934         if (exp->blk) {
 935             if (exp->eject_notifier_blk) {
 936                 notifier_remove(&exp->eject_notifier);
 937                 blk_unref(exp->eject_notifier_blk);
 938             }
 939             blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
 940                                             blk_aio_detach, exp);
 941             blk_unref(exp->blk);
 942             exp->blk = NULL;
 943         }
 944
 945         g_free(exp);
 946     }
 947 }
 948
 949 BlockBackend *nbd_export_get_blockdev(NBDExport *exp)
 950 {
 951     return exp->blk;
 952 }
 953
 954 void nbd_export_close_all(void)
 955 {
 956     NBDExport *exp, *next;
 957
 958     QTAILQ_FOREACH_SAFE(exp, &exports, next, next) {
 959         nbd_export_close(exp);
 960     }
 961 }
 962
 963 static int nbd_co_send_reply(NBDRequestData *req, NBDReply *reply, int len)
 964 {
 965     NBDClient *client = req->client;
 966     int ret;
 967
 968     g_assert(qemu_in_coroutine());
 969     qemu_co_mutex_lock(&client->send_lock);
 970     client->send_coroutine = qemu_coroutine_self();
 971
 972     if (!len) {
 973         ret = nbd_send_reply(client->ioc, reply);
 974     } else {
 975         qio_channel_set_cork(client->ioc, true);
 976         ret = nbd_send_reply(client->ioc, reply);
 977         if (ret == 0) {
 978             ret = nbd_write(client->ioc, req->data, len, NULL);
 979             if (ret < 0) {
 980                 ret = -EIO;
 981             }
 982         }
 983         qio_channel_set_cork(client->ioc, false);
 984     }
 985
 986     client->send_coroutine = NULL;
 987     qemu_co_mutex_unlock(&client->send_lock);
 988     return ret;
 989 }
 990
 991 /* nbd_co_receive_request
 992  * Collect a client request. Return 0 if request looks valid, -EIO to drop
 993  * connection right away, and any other negative value to report an error to
 994  * the client (although the caller may still need to disconnect after reporting
 995  * the error).
 996  */
 997 static int nbd_co_receive_request(NBDRequestData *req, NBDRequest *request)
 998 {
 999     NBDClient *client = req->client;
1000
1001     g_assert(qemu_in_coroutine());
1002     assert(client->recv_coroutine == qemu_coroutine_self());
1003     if (nbd_receive_request(client->ioc, request) < 0) {
1004         return -EIO;
1005     }
1006
1007     TRACE("Decoding type");
1008
1009     if (request->type != NBD_CMD_WRITE) {
1010         /* No payload, we are ready to read the next request.  */
1011         req->complete = true;
1012     }
1013
1014     if (request->type == NBD_CMD_DISC) {
1015         /* Special case: we're going to disconnect without a reply,
1016          * whether or not flags, from, or len are bogus */
1017         TRACE("Request type is DISCONNECT");
1018         return -EIO;
1019     }
1020
1021     /* Check for sanity in the parameters, part 1.  Defer as many
1022      * checks as possible until after reading any NBD_CMD_WRITE
1023      * payload, so we can try and keep the connection alive.  */
1024     if ((request->from + request->len) < request->from) {
1025         LOG("integer overflow detected, you're probably being attacked");
1026         return -EINVAL;
1027     }
1028
1029     if (request->type == NBD_CMD_READ || request->type == NBD_CMD_WRITE) {
1030         if (request->len > NBD_MAX_BUFFER_SIZE) {
1031             LOG("len (%" PRIu32" ) is larger than max len (%u)",
1032                 request->len, NBD_MAX_BUFFER_SIZE);
1033             return -EINVAL;
1034         }
1035
1036         req->data = blk_try_blockalign(client->exp->blk, request->len);
1037         if (req->data == NULL) {
1038             return -ENOMEM;
1039         }
1040     }
1041     if (request->type == NBD_CMD_WRITE) {
1042         TRACE("Reading %" PRIu32 " byte(s)", request->len);
1043
1044         if (nbd_read(client->ioc, req->data, request->len, NULL) < 0) {
1045             LOG("reading from socket failed");
1046             return -EIO;
1047         }
1048         req->complete = true;
1049     }
1050
1051     /* Sanity checks, part 2. */
1052     if (request->from + request->len > client->exp->size) {
1053         LOG("operation past EOF; From: %" PRIu64 ", Len: %" PRIu32
1054             ", Size: %" PRIu64, request->from, request->len,
1055             (uint64_t)client->exp->size);
1056         return request->type == NBD_CMD_WRITE ? -ENOSPC : -EINVAL;
1057     }
1058     if (request->flags & ~(NBD_CMD_FLAG_FUA | NBD_CMD_FLAG_NO_HOLE)) {
1059         LOG("unsupported flags (got 0x%x)", request->flags);
1060         return -EINVAL;
1061     }
1062     if (request->type != NBD_CMD_WRITE_ZEROES &&
1063         (request->flags & NBD_CMD_FLAG_NO_HOLE)) {
1064         LOG("unexpected flags (got 0x%x)", request->flags);
1065         return -EINVAL;
1066     }
1067
1068     return 0;
1069 }
1070
1071 /* Owns a reference to the NBDClient passed as opaque.  */
1072 static coroutine_fn void nbd_trip(void *opaque)
1073 {
1074     NBDClient *client = opaque;
1075     NBDExport *exp = client->exp;
1076     NBDRequestData *req;
1077     NBDRequest request = { 0 };    /* GCC thinks it can be used uninitialized */
1078     NBDReply reply;
1079     int ret;
1080     int flags;
1081     int reply_data_len = 0;
1082
1083     TRACE("Reading request.");
1084     if (client->closing) {
1085         nbd_client_put(client);
1086         return;
1087     }
1088
1089     req = nbd_request_get(client);
1090     ret = nbd_co_receive_request(req, &request);
1091     client->recv_coroutine = NULL;
1092     nbd_client_receive_next_request(client);
1093     if (ret == -EIO) {
1094         goto disconnect;
1095     }
1096
1097     reply.handle = request.handle;
1098     reply.error = 0;
1099
1100     if (ret < 0) {
1101         reply.error = -ret;
1102         goto reply;
1103     }
1104
1105     if (client->closing) {
1106         /*
1107          * The client may be closed when we are blocked in
1108          * nbd_co_receive_request()
1109          */
1110         goto done;
1111     }
1112
1113     switch (request.type) {
1114     case NBD_CMD_READ:
1115         TRACE("Request type is READ");
1116
1117         /* XXX: NBD Protocol only documents use of FUA with WRITE */
1118         if (request.flags & NBD_CMD_FLAG_FUA) {
1119             ret = blk_co_flush(exp->blk);
1120             if (ret < 0) {
1121                 LOG("flush failed");
1122                 reply.error = -ret;
1123                 break;
1124             }
1125         }
1126
1127         ret = blk_pread(exp->blk, request.from + exp->dev_offset,
1128                         req->data, request.len);
1129         if (ret < 0) {
1130             LOG("reading from file failed");
1131             reply.error = -ret;
1132             break;
1133         }
1134
1135         reply_data_len = request.len;
1136         TRACE("Read %" PRIu32" byte(s)", request.len);
1137
1138         break;
1139     case NBD_CMD_WRITE:
1140         TRACE("Request type is WRITE");
1141
1142         if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
1143             TRACE("Server is read-only, return error");
1144             reply.error = EROFS;
1145             break;
1146         }
1147
1148         TRACE("Writing to device");
1149
1150         flags = 0;
1151         if (request.flags & NBD_CMD_FLAG_FUA) {
1152             flags |= BDRV_REQ_FUA;
1153         }
1154         ret = blk_pwrite(exp->blk, request.from + exp->dev_offset,
1155                          req->data, request.len, flags);
1156         if (ret < 0) {
1157             LOG("writing to file failed");
1158             reply.error = -ret;
1159         }
1160
1161         break;
1162     case NBD_CMD_WRITE_ZEROES:
1163         TRACE("Request type is WRITE_ZEROES");
1164
1165         if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
1166             TRACE("Server is read-only, return error");
1167             reply.error = EROFS;
1168             break;
1169         }
1170
1171         TRACE("Writing to device");
1172
1173         flags = 0;
1174         if (request.flags & NBD_CMD_FLAG_FUA) {
1175             flags |= BDRV_REQ_FUA;
1176         }
1177         if (!(request.flags & NBD_CMD_FLAG_NO_HOLE)) {
1178             flags |= BDRV_REQ_MAY_UNMAP;
1179         }
1180         ret = blk_pwrite_zeroes(exp->blk, request.from + exp->dev_offset,
1181                                 request.len, flags);
1182         if (ret < 0) {
1183             LOG("writing to file failed");
1184             reply.error = -ret;
1185         }
1186
1187         break;
1188     case NBD_CMD_DISC:
1189         /* unreachable, thanks to special case in nbd_co_receive_request() */
1190         abort();
1191
1192     case NBD_CMD_FLUSH:
1193         TRACE("Request type is FLUSH");
1194
1195         ret = blk_co_flush(exp->blk);
1196         if (ret < 0) {
1197             LOG("flush failed");
1198             reply.error = -ret;
1199         }
1200
1201         break;
1202     case NBD_CMD_TRIM:
1203         TRACE("Request type is TRIM");
1204         ret = blk_co_pdiscard(exp->blk, request.from + exp->dev_offset,
1205                               request.len);
1206         if (ret < 0) {
1207             LOG("discard failed");
1208             reply.error = -ret;
1209         }
1210
1211         break;
1212     default:
1213         LOG("invalid request type (%" PRIu32 ") received", request.type);
1214         reply.error = EINVAL;
1215     }
1216
1217 reply:
1218     /* We must disconnect after NBD_CMD_WRITE if we did not
1219      * read the payload.
1220      */
1221     if (nbd_co_send_reply(req, &reply, reply_data_len) < 0 || !req->complete) {
1222         goto disconnect;
1223     }
1224
1225     TRACE("Request/Reply complete");
1226
1227 done:
1228     nbd_request_put(req);
1229     nbd_client_put(client);
1230     return;
1231
1232 disconnect:
1233     nbd_request_put(req);
1234     client_close(client, true);
1235     nbd_client_put(client);
1236 }
1237
1238 static void nbd_client_receive_next_request(NBDClient *client)
1239 {
1240     if (!client->recv_coroutine && client->nb_requests < MAX_NBD_REQUESTS) {
1241         nbd_client_get(client);
1242         client->recv_coroutine = qemu_coroutine_create(nbd_trip, client);
1243         aio_co_schedule(client->exp->ctx, client->recv_coroutine);
1244     }
1245 }
1246
1247 static coroutine_fn void nbd_co_client_start(void *opaque)
1248 {
1249     NBDClient *client = opaque;
1250     NBDExport *exp = client->exp;
1251
1252     if (exp) {
1253         nbd_export_get(exp);
1254         QTAILQ_INSERT_TAIL(&exp->clients, client, next);
1255     }
1256     qemu_co_mutex_init(&client->send_lock);
1257
1258     if (nbd_negotiate(client)) {
1259         client_close(client, false);
1260         return;
1261     }
1262
1263     nbd_client_receive_next_request(client);
1264 }
1265
1266 /*
1267  * Create a new client listener on the given export @exp, using the
1268  * given channel @sioc.  Begin servicing it in a coroutine.  When the
1269  * connection closes, call @close_fn with an indication of whether the
1270  * client completed negotiation.
1271  */
1272 void nbd_client_new(NBDExport *exp,
1273                     QIOChannelSocket *sioc,
1274                     QCryptoTLSCreds *tlscreds,
1275                     const char *tlsaclname,
1276                     void (*close_fn)(NBDClient *, bool))
1277 {
1278     NBDClient *client;
1279     Coroutine *co;
1280
1281     client = g_malloc0(sizeof(NBDClient));
1282     client->refcount = 1;
1283     client->exp = exp;
1284     client->tlscreds = tlscreds;
1285     if (tlscreds) {
1286         object_ref(OBJECT(client->tlscreds));
1287     }
1288     client->tlsaclname = g_strdup(tlsaclname);
1289     client->sioc = sioc;
1290     object_ref(OBJECT(client->sioc));
1291     client->ioc = QIO_CHANNEL(sioc);
1292     object_ref(OBJECT(client->ioc));
1293     client->close_fn = close_fn;
1294
1295     co = qemu_coroutine_create(nbd_co_client_start, client);
1296     qemu_coroutine_enter(co);
1297 }