nbd/server.c

   1 /*
   2  *  Copyright (C) 2016-2017 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 "trace.h"
  23 #include "nbd-internal.h"
  24
  25 static int system_errno_to_nbd_errno(int err)
  26 {
  27     switch (err) {
  28     case 0:
  29         return NBD_SUCCESS;
  30     case EPERM:
  31     case EROFS:
  32         return NBD_EPERM;
  33     case EIO:
  34         return NBD_EIO;
  35     case ENOMEM:
  36         return NBD_ENOMEM;
  37 #ifdef EDQUOT
  38     case EDQUOT:
  39 #endif
  40     case EFBIG:
  41     case ENOSPC:
  42         return NBD_ENOSPC;
  43     case ESHUTDOWN:
  44         return NBD_ESHUTDOWN;
  45     case EINVAL:
  46     default:
  47         return NBD_EINVAL;
  48     }
  49 }
  50
  51 /* Definitions for opaque data types */
  52
  53 typedef struct NBDRequestData NBDRequestData;
  54
  55 struct NBDRequestData {
  56     QSIMPLEQ_ENTRY(NBDRequestData) entry;
  57     NBDClient *client;
  58     uint8_t *data;
  59     bool complete;
  60 };
  61
  62 struct NBDExport {
  63     int refcount;
  64     void (*close)(NBDExport *exp);
  65
  66     BlockBackend *blk;
  67     char *name;
  68     char *description;
  69     off_t dev_offset;
  70     off_t size;
  71     uint16_t nbdflags;
  72     QTAILQ_HEAD(, NBDClient) clients;
  73     QTAILQ_ENTRY(NBDExport) next;
  74
  75     AioContext *ctx;
  76
  77     BlockBackend *eject_notifier_blk;
  78     Notifier eject_notifier;
  79 };
  80
  81 static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
  82
  83 struct NBDClient {
  84     int refcount;
  85     void (*close_fn)(NBDClient *client, bool negotiated);
  86
  87     bool no_zeroes;
  88     NBDExport *exp;
  89     QCryptoTLSCreds *tlscreds;
  90     char *tlsaclname;
  91     QIOChannelSocket *sioc; /* The underlying data channel */
  92     QIOChannel *ioc; /* The current I/O channel which may differ (eg TLS) */
  93
  94     Coroutine *recv_coroutine;
  95
  96     CoMutex send_lock;
  97     Coroutine *send_coroutine;
  98
  99     QTAILQ_ENTRY(NBDClient) next;
 100     int nb_requests;
 101     bool closing;
 102 };
 103
 104 /* That's all folks */
 105
 106 static void nbd_client_receive_next_request(NBDClient *client);
 107
 108 /* Basic flow for negotiation
 109
 110    Server         Client
 111    Negotiate
 112
 113    or
 114
 115    Server         Client
 116    Negotiate #1
 117                   Option
 118    Negotiate #2
 119
 120    ----
 121
 122    followed by
 123
 124    Server         Client
 125                   Request
 126    Response
 127                   Request
 128    Response
 129                   ...
 130    ...
 131                   Request (type == 2)
 132
 133 */
 134
 135 /* Send a reply header, including length, but no payload.
 136  * Return -errno on error, 0 on success. */
 137 static int nbd_negotiate_send_rep_len(QIOChannel *ioc, uint32_t type,
 138                                       uint32_t opt, uint32_t len, Error **errp)
 139 {
 140     uint64_t magic;
 141
 142     trace_nbd_negotiate_send_rep_len(opt, nbd_opt_lookup(opt),
 143                                      type, nbd_rep_lookup(type), len);
 144
 145     magic = cpu_to_be64(NBD_REP_MAGIC);
 146     if (nbd_write(ioc, &magic, sizeof(magic), errp) < 0) {
 147         error_prepend(errp, "write failed (rep magic): ");
 148         return -EINVAL;
 149     }
 150
 151     opt = cpu_to_be32(opt);
 152     if (nbd_write(ioc, &opt, sizeof(opt), errp) < 0) {
 153         error_prepend(errp, "write failed (rep opt): ");
 154         return -EINVAL;
 155     }
 156
 157     type = cpu_to_be32(type);
 158     if (nbd_write(ioc, &type, sizeof(type), errp) < 0) {
 159         error_prepend(errp, "write failed (rep type): ");
 160         return -EINVAL;
 161     }
 162
 163     len = cpu_to_be32(len);
 164     if (nbd_write(ioc, &len, sizeof(len), errp) < 0) {
 165         error_prepend(errp, "write failed (rep data length): ");
 166         return -EINVAL;
 167     }
 168     return 0;
 169 }
 170
 171 /* Send a reply header with default 0 length.
 172  * Return -errno on error, 0 on success. */
 173 static int nbd_negotiate_send_rep(QIOChannel *ioc, uint32_t type, uint32_t opt,
 174                                   Error **errp)
 175 {
 176     return nbd_negotiate_send_rep_len(ioc, type, opt, 0, errp);
 177 }
 178
 179 /* Send an error reply.
 180  * Return -errno on error, 0 on success. */
 181 static int GCC_FMT_ATTR(5, 6)
 182 nbd_negotiate_send_rep_err(QIOChannel *ioc, uint32_t type,
 183                            uint32_t opt, Error **errp, const char *fmt, ...)
 184 {
 185     va_list va;
 186     char *msg;
 187     int ret;
 188     size_t len;
 189
 190     va_start(va, fmt);
 191     msg = g_strdup_vprintf(fmt, va);
 192     va_end(va);
 193     len = strlen(msg);
 194     assert(len < 4096);
 195     trace_nbd_negotiate_send_rep_err(msg);
 196     ret = nbd_negotiate_send_rep_len(ioc, type, opt, len, errp);
 197     if (ret < 0) {
 198         goto out;
 199     }
 200     if (nbd_write(ioc, msg, len, errp) < 0) {
 201         error_prepend(errp, "write failed (error message): ");
 202         ret = -EIO;
 203     } else {
 204         ret = 0;
 205     }
 206
 207 out:
 208     g_free(msg);
 209     return ret;
 210 }
 211
 212 /* Send a single NBD_REP_SERVER reply to NBD_OPT_LIST, including payload.
 213  * Return -errno on error, 0 on success. */
 214 static int nbd_negotiate_send_rep_list(QIOChannel *ioc, NBDExport *exp,
 215                                        Error **errp)
 216 {
 217     size_t name_len, desc_len;
 218     uint32_t len;
 219     const char *name = exp->name ? exp->name : "";
 220     const char *desc = exp->description ? exp->description : "";
 221     int ret;
 222
 223     trace_nbd_negotiate_send_rep_list(name, desc);
 224     name_len = strlen(name);
 225     desc_len = strlen(desc);
 226     len = name_len + desc_len + sizeof(len);
 227     ret = nbd_negotiate_send_rep_len(ioc, NBD_REP_SERVER, NBD_OPT_LIST, len,
 228                                      errp);
 229     if (ret < 0) {
 230         return ret;
 231     }
 232
 233     len = cpu_to_be32(name_len);
 234     if (nbd_write(ioc, &len, sizeof(len), errp) < 0) {
 235         error_prepend(errp, "write failed (name length): ");
 236         return -EINVAL;
 237     }
 238
 239     if (nbd_write(ioc, name, name_len, errp) < 0) {
 240         error_prepend(errp, "write failed (name buffer): ");
 241         return -EINVAL;
 242     }
 243
 244     if (nbd_write(ioc, desc, desc_len, errp) < 0) {
 245         error_prepend(errp, "write failed (description buffer): ");
 246         return -EINVAL;
 247     }
 248
 249     return 0;
 250 }
 251
 252 /* Process the NBD_OPT_LIST command, with a potential series of replies.
 253  * Return -errno on error, 0 on success. */
 254 static int nbd_negotiate_handle_list(NBDClient *client, uint32_t length,
 255                                      Error **errp)
 256 {
 257     NBDExport *exp;
 258
 259     if (length) {
 260         if (nbd_drop(client->ioc, length, errp) < 0) {
 261             return -EIO;
 262         }
 263         return nbd_negotiate_send_rep_err(client->ioc,
 264                                           NBD_REP_ERR_INVALID, NBD_OPT_LIST,
 265                                           errp,
 266                                           "OPT_LIST should not have length");
 267     }
 268
 269     /* For each export, send a NBD_REP_SERVER reply. */
 270     QTAILQ_FOREACH(exp, &exports, next) {
 271         if (nbd_negotiate_send_rep_list(client->ioc, exp, errp)) {
 272             return -EINVAL;
 273         }
 274     }
 275     /* Finish with a NBD_REP_ACK. */
 276     return nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, NBD_OPT_LIST, errp);
 277 }
 278
 279 static int nbd_negotiate_handle_export_name(NBDClient *client, uint32_t length,
 280                                             Error **errp)
 281 {
 282     char name[NBD_MAX_NAME_SIZE + 1];
 283
 284     /* Client sends:
 285         [20 ..  xx]   export name (length bytes)
 286      */
 287     trace_nbd_negotiate_handle_export_name();
 288     if (length >= sizeof(name)) {
 289         error_setg(errp, "Bad length received");
 290         return -EINVAL;
 291     }
 292     if (nbd_read(client->ioc, name, length, errp) < 0) {
 293         error_prepend(errp, "read failed: ");
 294         return -EINVAL;
 295     }
 296     name[length] = '\0';
 297
 298     trace_nbd_negotiate_handle_export_name_request(name);
 299
 300     client->exp = nbd_export_find(name);
 301     if (!client->exp) {
 302         error_setg(errp, "export not found");
 303         return -EINVAL;
 304     }
 305
 306     QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
 307     nbd_export_get(client->exp);
 308
 309     return 0;
 310 }
 311
 312 /* Handle NBD_OPT_STARTTLS. Return NULL to drop connection, or else the
 313  * new channel for all further (now-encrypted) communication. */
 314 static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client,
 315                                                  uint32_t length,
 316                                                  Error **errp)
 317 {
 318     QIOChannel *ioc;
 319     QIOChannelTLS *tioc;
 320     struct NBDTLSHandshakeData data = { 0 };
 321
 322     trace_nbd_negotiate_handle_starttls();
 323     ioc = client->ioc;
 324     if (length) {
 325         if (nbd_drop(ioc, length, errp) < 0) {
 326             return NULL;
 327         }
 328         nbd_negotiate_send_rep_err(ioc, NBD_REP_ERR_INVALID, NBD_OPT_STARTTLS,
 329                                    errp,
 330                                    "OPT_STARTTLS should not have length");
 331         return NULL;
 332     }
 333
 334     if (nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK,
 335                                NBD_OPT_STARTTLS, errp) < 0) {
 336         return NULL;
 337     }
 338
 339     tioc = qio_channel_tls_new_server(ioc,
 340                                       client->tlscreds,
 341                                       client->tlsaclname,
 342                                       errp);
 343     if (!tioc) {
 344         return NULL;
 345     }
 346
 347     qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-server-tls");
 348     trace_nbd_negotiate_handle_starttls_handshake();
 349     data.loop = g_main_loop_new(g_main_context_default(), FALSE);
 350     qio_channel_tls_handshake(tioc,
 351                               nbd_tls_handshake,
 352                               &data,
 353                               NULL);
 354
 355     if (!data.complete) {
 356         g_main_loop_run(data.loop);
 357     }
 358     g_main_loop_unref(data.loop);
 359     if (data.error) {
 360         object_unref(OBJECT(tioc));
 361         error_propagate(errp, data.error);
 362         return NULL;
 363     }
 364
 365     return QIO_CHANNEL(tioc);
 366 }
 367
 368 /* nbd_negotiate_options
 369  * Process all NBD_OPT_* client option commands.
 370  * Return:
 371  * -errno  on error, errp is set
 372  * 0       on successful negotiation, errp is not set
 373  * 1       if client sent NBD_OPT_ABORT, i.e. on valid disconnect,
 374  *         errp is not set
 375  */
 376 static int nbd_negotiate_options(NBDClient *client, Error **errp)
 377 {
 378     uint32_t flags;
 379     bool fixedNewstyle = false;
 380
 381     /* Client sends:
 382         [ 0 ..   3]   client flags
 383
 384         [ 0 ..   7]   NBD_OPTS_MAGIC
 385         [ 8 ..  11]   NBD option
 386         [12 ..  15]   Data length
 387         ...           Rest of request
 388
 389         [ 0 ..   7]   NBD_OPTS_MAGIC
 390         [ 8 ..  11]   Second NBD option
 391         [12 ..  15]   Data length
 392         ...           Rest of request
 393     */
 394
 395     if (nbd_read(client->ioc, &flags, sizeof(flags), errp) < 0) {
 396         error_prepend(errp, "read failed: ");
 397         return -EIO;
 398     }
 399     trace_nbd_negotiate_options_flags();
 400     be32_to_cpus(&flags);
 401     if (flags & NBD_FLAG_C_FIXED_NEWSTYLE) {
 402         trace_nbd_negotiate_options_newstyle();
 403         fixedNewstyle = true;
 404         flags &= ~NBD_FLAG_C_FIXED_NEWSTYLE;
 405     }
 406     if (flags & NBD_FLAG_C_NO_ZEROES) {
 407         trace_nbd_negotiate_options_no_zeroes();
 408         client->no_zeroes = true;
 409         flags &= ~NBD_FLAG_C_NO_ZEROES;
 410     }
 411     if (flags != 0) {
 412         error_setg(errp, "Unknown client flags 0x%" PRIx32 " received", flags);
 413         return -EIO;
 414     }
 415
 416     while (1) {
 417         int ret;
 418         uint32_t option, length;
 419         uint64_t magic;
 420
 421         if (nbd_read(client->ioc, &magic, sizeof(magic), errp) < 0) {
 422             error_prepend(errp, "read failed: ");
 423             return -EINVAL;
 424         }
 425         magic = be64_to_cpu(magic);
 426         trace_nbd_negotiate_options_check_magic(magic);
 427         if (magic != NBD_OPTS_MAGIC) {
 428             error_setg(errp, "Bad magic received");
 429             return -EINVAL;
 430         }
 431
 432         if (nbd_read(client->ioc, &option,
 433                      sizeof(option), errp) < 0) {
 434             error_prepend(errp, "read failed: ");
 435             return -EINVAL;
 436         }
 437         option = be32_to_cpu(option);
 438
 439         if (nbd_read(client->ioc, &length, sizeof(length), errp) < 0) {
 440             error_prepend(errp, "read failed: ");
 441             return -EINVAL;
 442         }
 443         length = be32_to_cpu(length);
 444
 445         trace_nbd_negotiate_options_check_option(option,
 446                                                  nbd_opt_lookup(option));
 447         if (client->tlscreds &&
 448             client->ioc == (QIOChannel *)client->sioc) {
 449             QIOChannel *tioc;
 450             if (!fixedNewstyle) {
 451                 error_setg(errp, "Unsupported option 0x%" PRIx32, option);
 452                 return -EINVAL;
 453             }
 454             switch (option) {
 455             case NBD_OPT_STARTTLS:
 456                 tioc = nbd_negotiate_handle_starttls(client, length, errp);
 457                 if (!tioc) {
 458                     return -EIO;
 459                 }
 460                 object_unref(OBJECT(client->ioc));
 461                 client->ioc = QIO_CHANNEL(tioc);
 462                 break;
 463
 464             case NBD_OPT_EXPORT_NAME:
 465                 /* No way to return an error to client, so drop connection */
 466                 error_setg(errp, "Option 0x%x not permitted before TLS",
 467                            option);
 468                 return -EINVAL;
 469
 470             default:
 471                 if (nbd_drop(client->ioc, length, errp) < 0) {
 472                     return -EIO;
 473                 }
 474                 ret = nbd_negotiate_send_rep_err(client->ioc,
 475                                                  NBD_REP_ERR_TLS_REQD,
 476                                                  option, errp,
 477                                                  "Option 0x%" PRIx32
 478                                                  "not permitted before TLS",
 479                                                  option);
 480                 if (ret < 0) {
 481                     return ret;
 482                 }
 483                 /* Let the client keep trying, unless they asked to
 484                  * quit. In this mode, we've already sent an error, so
 485                  * we can't ack the abort.  */
 486                 if (option == NBD_OPT_ABORT) {
 487                     return 1;
 488                 }
 489                 break;
 490             }
 491         } else if (fixedNewstyle) {
 492             switch (option) {
 493             case NBD_OPT_LIST:
 494                 ret = nbd_negotiate_handle_list(client, length, errp);
 495                 if (ret < 0) {
 496                     return ret;
 497                 }
 498                 break;
 499
 500             case NBD_OPT_ABORT:
 501                 /* NBD spec says we must try to reply before
 502                  * disconnecting, but that we must also tolerate
 503                  * guests that don't wait for our reply. */
 504                 nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, option, NULL);
 505                 return 1;
 506
 507             case NBD_OPT_EXPORT_NAME:
 508                 return nbd_negotiate_handle_export_name(client, length, errp);
 509
 510             case NBD_OPT_STARTTLS:
 511                 if (nbd_drop(client->ioc, length, errp) < 0) {
 512                     return -EIO;
 513                 }
 514                 if (client->tlscreds) {
 515                     ret = nbd_negotiate_send_rep_err(client->ioc,
 516                                                      NBD_REP_ERR_INVALID,
 517                                                      option, errp,
 518                                                      "TLS already enabled");
 519                 } else {
 520                     ret = nbd_negotiate_send_rep_err(client->ioc,
 521                                                      NBD_REP_ERR_POLICY,
 522                                                      option, errp,
 523                                                      "TLS not configured");
 524                 }
 525                 if (ret < 0) {
 526                     return ret;
 527                 }
 528                 break;
 529             default:
 530                 if (nbd_drop(client->ioc, length, errp) < 0) {
 531                     return -EIO;
 532                 }
 533                 ret = nbd_negotiate_send_rep_err(client->ioc,
 534                                                  NBD_REP_ERR_UNSUP,
 535                                                  option, errp,
 536                                                  "Unsupported option 0x%"
 537                                                  PRIx32 " (%s)", option,
 538                                                  nbd_opt_lookup(option));
 539                 if (ret < 0) {
 540                     return ret;
 541                 }
 542                 break;
 543             }
 544         } else {
 545             /*
 546              * If broken new-style we should drop the connection
 547              * for anything except NBD_OPT_EXPORT_NAME
 548              */
 549             switch (option) {
 550             case NBD_OPT_EXPORT_NAME:
 551                 return nbd_negotiate_handle_export_name(client, length, errp);
 552
 553             default:
 554                 error_setg(errp, "Unsupported option 0x%" PRIx32 " (%s)",
 555                            option, nbd_opt_lookup(option));
 556                 return -EINVAL;
 557             }
 558         }
 559     }
 560 }
 561
 562 /* nbd_negotiate
 563  * Return:
 564  * -errno  on error, errp is set
 565  * 0       on successful negotiation, errp is not set
 566  * 1       if client sent NBD_OPT_ABORT, i.e. on valid disconnect,
 567  *         errp is not set
 568  */
 569 static coroutine_fn int nbd_negotiate(NBDClient *client, Error **errp)
 570 {
 571     char buf[8 + 8 + 8 + 128];
 572     int ret;
 573     const uint16_t myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM |
 574                               NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA |
 575                               NBD_FLAG_SEND_WRITE_ZEROES);
 576     bool oldStyle;
 577     size_t len;
 578
 579     /* Old style negotiation header without options
 580         [ 0 ..   7]   passwd       ("NBDMAGIC")
 581         [ 8 ..  15]   magic        (NBD_CLIENT_MAGIC)
 582         [16 ..  23]   size
 583         [24 ..  25]   server flags (0)
 584         [26 ..  27]   export flags
 585         [28 .. 151]   reserved     (0)
 586
 587        New style negotiation header with options
 588         [ 0 ..   7]   passwd       ("NBDMAGIC")
 589         [ 8 ..  15]   magic        (NBD_OPTS_MAGIC)
 590         [16 ..  17]   server flags (0)
 591         ....options sent....
 592         [18 ..  25]   size
 593         [26 ..  27]   export flags
 594         [28 .. 151]   reserved     (0, omit if no_zeroes)
 595      */
 596
 597     qio_channel_set_blocking(client->ioc, false, NULL);
 598
 599     trace_nbd_negotiate_begin();
 600     memset(buf, 0, sizeof(buf));
 601     memcpy(buf, "NBDMAGIC", 8);
 602
 603     oldStyle = client->exp != NULL && !client->tlscreds;
 604     if (oldStyle) {
 605         trace_nbd_negotiate_old_style(client->exp->size,
 606                                       client->exp->nbdflags | myflags);
 607         stq_be_p(buf + 8, NBD_CLIENT_MAGIC);
 608         stq_be_p(buf + 16, client->exp->size);
 609         stw_be_p(buf + 26, client->exp->nbdflags | myflags);
 610
 611         if (nbd_write(client->ioc, buf, sizeof(buf), errp) < 0) {
 612             error_prepend(errp, "write failed: ");
 613             return -EINVAL;
 614         }
 615     } else {
 616         stq_be_p(buf + 8, NBD_OPTS_MAGIC);
 617         stw_be_p(buf + 16, NBD_FLAG_FIXED_NEWSTYLE | NBD_FLAG_NO_ZEROES);
 618
 619         if (nbd_write(client->ioc, buf, 18, errp) < 0) {
 620             error_prepend(errp, "write failed: ");
 621             return -EINVAL;
 622         }
 623         ret = nbd_negotiate_options(client, errp);
 624         if (ret != 0) {
 625             if (ret < 0) {
 626                 error_prepend(errp, "option negotiation failed: ");
 627             }
 628             return ret;
 629         }
 630
 631         trace_nbd_negotiate_new_style_size_flags(
 632             client->exp->size, client->exp->nbdflags | myflags);
 633         stq_be_p(buf + 18, client->exp->size);
 634         stw_be_p(buf + 26, client->exp->nbdflags | myflags);
 635         len = client->no_zeroes ? 10 : sizeof(buf) - 18;
 636         ret = nbd_write(client->ioc, buf + 18, len, errp);
 637         if (ret < 0) {
 638             error_prepend(errp, "write failed: ");
 639             return ret;
 640         }
 641     }
 642
 643     trace_nbd_negotiate_success();
 644
 645     return 0;
 646 }
 647
 648 static int nbd_receive_request(QIOChannel *ioc, NBDRequest *request,
 649                                Error **errp)
 650 {
 651     uint8_t buf[NBD_REQUEST_SIZE];
 652     uint32_t magic;
 653     int ret;
 654
 655     ret = nbd_read(ioc, buf, sizeof(buf), errp);
 656     if (ret < 0) {
 657         return ret;
 658     }
 659
 660     /* Request
 661        [ 0 ..  3]   magic   (NBD_REQUEST_MAGIC)
 662        [ 4 ..  5]   flags   (NBD_CMD_FLAG_FUA, ...)
 663        [ 6 ..  7]   type    (NBD_CMD_READ, ...)
 664        [ 8 .. 15]   handle
 665        [16 .. 23]   from
 666        [24 .. 27]   len
 667      */
 668
 669     magic = ldl_be_p(buf);
 670     request->flags  = lduw_be_p(buf + 4);
 671     request->type   = lduw_be_p(buf + 6);
 672     request->handle = ldq_be_p(buf + 8);
 673     request->from   = ldq_be_p(buf + 16);
 674     request->len    = ldl_be_p(buf + 24);
 675
 676     trace_nbd_receive_request(magic, request->flags, request->type,
 677                               request->from, request->len);
 678
 679     if (magic != NBD_REQUEST_MAGIC) {
 680         error_setg(errp, "invalid magic (got 0x%" PRIx32 ")", magic);
 681         return -EINVAL;
 682     }
 683     return 0;
 684 }
 685
 686 static int nbd_send_reply(QIOChannel *ioc, NBDReply *reply, Error **errp)
 687 {
 688     uint8_t buf[NBD_REPLY_SIZE];
 689
 690     reply->error = system_errno_to_nbd_errno(reply->error);
 691
 692     trace_nbd_send_reply(reply->error, reply->handle);
 693
 694     /* Reply
 695        [ 0 ..  3]    magic   (NBD_REPLY_MAGIC)
 696        [ 4 ..  7]    error   (0 == no error)
 697        [ 7 .. 15]    handle
 698      */
 699     stl_be_p(buf, NBD_REPLY_MAGIC);
 700     stl_be_p(buf + 4, reply->error);
 701     stq_be_p(buf + 8, reply->handle);
 702
 703     return nbd_write(ioc, buf, sizeof(buf), errp);
 704 }
 705
 706 #define MAX_NBD_REQUESTS 16
 707
 708 void nbd_client_get(NBDClient *client)
 709 {
 710     client->refcount++;
 711 }
 712
 713 void nbd_client_put(NBDClient *client)
 714 {
 715     if (--client->refcount == 0) {
 716         /* The last reference should be dropped by client->close,
 717          * which is called by client_close.
 718          */
 719         assert(client->closing);
 720
 721         qio_channel_detach_aio_context(client->ioc);
 722         object_unref(OBJECT(client->sioc));
 723         object_unref(OBJECT(client->ioc));
 724         if (client->tlscreds) {
 725             object_unref(OBJECT(client->tlscreds));
 726         }
 727         g_free(client->tlsaclname);
 728         if (client->exp) {
 729             QTAILQ_REMOVE(&client->exp->clients, client, next);
 730             nbd_export_put(client->exp);
 731         }
 732         g_free(client);
 733     }
 734 }
 735
 736 static void client_close(NBDClient *client, bool negotiated)
 737 {
 738     if (client->closing) {
 739         return;
 740     }
 741
 742     client->closing = true;
 743
 744     /* Force requests to finish.  They will drop their own references,
 745      * then we'll close the socket and free the NBDClient.
 746      */
 747     qio_channel_shutdown(client->ioc, QIO_CHANNEL_SHUTDOWN_BOTH,
 748                          NULL);
 749
 750     /* Also tell the client, so that they release their reference.  */
 751     if (client->close_fn) {
 752         client->close_fn(client, negotiated);
 753     }
 754 }
 755
 756 static NBDRequestData *nbd_request_get(NBDClient *client)
 757 {
 758     NBDRequestData *req;
 759
 760     assert(client->nb_requests <= MAX_NBD_REQUESTS - 1);
 761     client->nb_requests++;
 762
 763     req = g_new0(NBDRequestData, 1);
 764     nbd_client_get(client);
 765     req->client = client;
 766     return req;
 767 }
 768
 769 static void nbd_request_put(NBDRequestData *req)
 770 {
 771     NBDClient *client = req->client;
 772
 773     if (req->data) {
 774         qemu_vfree(req->data);
 775     }
 776     g_free(req);
 777
 778     client->nb_requests--;
 779     nbd_client_receive_next_request(client);
 780
 781     nbd_client_put(client);
 782 }
 783
 784 static void blk_aio_attached(AioContext *ctx, void *opaque)
 785 {
 786     NBDExport *exp = opaque;
 787     NBDClient *client;
 788
 789     trace_nbd_blk_aio_attached(exp->name, ctx);
 790
 791     exp->ctx = ctx;
 792
 793     QTAILQ_FOREACH(client, &exp->clients, next) {
 794         qio_channel_attach_aio_context(client->ioc, ctx);
 795         if (client->recv_coroutine) {
 796             aio_co_schedule(ctx, client->recv_coroutine);
 797         }
 798         if (client->send_coroutine) {
 799             aio_co_schedule(ctx, client->send_coroutine);
 800         }
 801     }
 802 }
 803
 804 static void blk_aio_detach(void *opaque)
 805 {
 806     NBDExport *exp = opaque;
 807     NBDClient *client;
 808
 809     trace_nbd_blk_aio_detach(exp->name, exp->ctx);
 810
 811     QTAILQ_FOREACH(client, &exp->clients, next) {
 812         qio_channel_detach_aio_context(client->ioc);
 813     }
 814
 815     exp->ctx = NULL;
 816 }
 817
 818 static void nbd_eject_notifier(Notifier *n, void *data)
 819 {
 820     NBDExport *exp = container_of(n, NBDExport, eject_notifier);
 821     nbd_export_close(exp);
 822 }
 823
 824 NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset, off_t size,
 825                           uint16_t nbdflags, void (*close)(NBDExport *),
 826                           bool writethrough, BlockBackend *on_eject_blk,
 827                           Error **errp)
 828 {
 829     BlockBackend *blk;
 830     NBDExport *exp = g_malloc0(sizeof(NBDExport));
 831     uint64_t perm;
 832     int ret;
 833
 834     /* Don't allow resize while the NBD server is running, otherwise we don't
 835      * care what happens with the node. */
 836     perm = BLK_PERM_CONSISTENT_READ;
 837     if ((nbdflags & NBD_FLAG_READ_ONLY) == 0) {
 838         perm |= BLK_PERM_WRITE;
 839     }
 840     blk = blk_new(perm, BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
 841                         BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD);
 842     ret = blk_insert_bs(blk, bs, errp);
 843     if (ret < 0) {
 844         goto fail;
 845     }
 846     blk_set_enable_write_cache(blk, !writethrough);
 847
 848     exp->refcount = 1;
 849     QTAILQ_INIT(&exp->clients);
 850     exp->blk = blk;
 851     exp->dev_offset = dev_offset;
 852     exp->nbdflags = nbdflags;
 853     exp->size = size < 0 ? blk_getlength(blk) : size;
 854     if (exp->size < 0) {
 855         error_setg_errno(errp, -exp->size,
 856                          "Failed to determine the NBD export's length");
 857         goto fail;
 858     }
 859     exp->size -= exp->size % BDRV_SECTOR_SIZE;
 860
 861     exp->close = close;
 862     exp->ctx = blk_get_aio_context(blk);
 863     blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
 864
 865     if (on_eject_blk) {
 866         blk_ref(on_eject_blk);
 867         exp->eject_notifier_blk = on_eject_blk;
 868         exp->eject_notifier.notify = nbd_eject_notifier;
 869         blk_add_remove_bs_notifier(on_eject_blk, &exp->eject_notifier);
 870     }
 871
 872     /*
 873      * NBD exports are used for non-shared storage migration.  Make sure
 874      * that BDRV_O_INACTIVE is cleared and the image is ready for write
 875      * access since the export could be available before migration handover.
 876      */
 877     aio_context_acquire(exp->ctx);
 878     blk_invalidate_cache(blk, NULL);
 879     aio_context_release(exp->ctx);
 880     return exp;
 881
 882 fail:
 883     blk_unref(blk);
 884     g_free(exp);
 885     return NULL;
 886 }
 887
 888 NBDExport *nbd_export_find(const char *name)
 889 {
 890     NBDExport *exp;
 891     QTAILQ_FOREACH(exp, &exports, next) {
 892         if (strcmp(name, exp->name) == 0) {
 893             return exp;
 894         }
 895     }
 896
 897     return NULL;
 898 }
 899
 900 void nbd_export_set_name(NBDExport *exp, const char *name)
 901 {
 902     if (exp->name == name) {
 903         return;
 904     }
 905
 906     nbd_export_get(exp);
 907     if (exp->name != NULL) {
 908         g_free(exp->name);
 909         exp->name = NULL;
 910         QTAILQ_REMOVE(&exports, exp, next);
 911         nbd_export_put(exp);
 912     }
 913     if (name != NULL) {
 914         nbd_export_get(exp);
 915         exp->name = g_strdup(name);
 916         QTAILQ_INSERT_TAIL(&exports, exp, next);
 917     }
 918     nbd_export_put(exp);
 919 }
 920
 921 void nbd_export_set_description(NBDExport *exp, const char *description)
 922 {
 923     g_free(exp->description);
 924     exp->description = g_strdup(description);
 925 }
 926
 927 void nbd_export_close(NBDExport *exp)
 928 {
 929     NBDClient *client, *next;
 930
 931     nbd_export_get(exp);
 932     QTAILQ_FOREACH_SAFE(client, &exp->clients, next, next) {
 933         client_close(client, true);
 934     }
 935     nbd_export_set_name(exp, NULL);
 936     nbd_export_set_description(exp, NULL);
 937     nbd_export_put(exp);
 938 }
 939
 940 void nbd_export_get(NBDExport *exp)
 941 {
 942     assert(exp->refcount > 0);
 943     exp->refcount++;
 944 }
 945
 946 void nbd_export_put(NBDExport *exp)
 947 {
 948     assert(exp->refcount > 0);
 949     if (exp->refcount == 1) {
 950         nbd_export_close(exp);
 951     }
 952
 953     if (--exp->refcount == 0) {
 954         assert(exp->name == NULL);
 955         assert(exp->description == NULL);
 956
 957         if (exp->close) {
 958             exp->close(exp);
 959         }
 960
 961         if (exp->blk) {
 962             if (exp->eject_notifier_blk) {
 963                 notifier_remove(&exp->eject_notifier);
 964                 blk_unref(exp->eject_notifier_blk);
 965             }
 966             blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
 967                                             blk_aio_detach, exp);
 968             blk_unref(exp->blk);
 969             exp->blk = NULL;
 970         }
 971
 972         g_free(exp);
 973     }
 974 }
 975
 976 BlockBackend *nbd_export_get_blockdev(NBDExport *exp)
 977 {
 978     return exp->blk;
 979 }
 980
 981 void nbd_export_close_all(void)
 982 {
 983     NBDExport *exp, *next;
 984
 985     QTAILQ_FOREACH_SAFE(exp, &exports, next, next) {
 986         nbd_export_close(exp);
 987     }
 988 }
 989
 990 static int nbd_co_send_reply(NBDRequestData *req, NBDReply *reply, int len,
 991                              Error **errp)
 992 {
 993     NBDClient *client = req->client;
 994     int ret;
 995
 996     g_assert(qemu_in_coroutine());
 997
 998     trace_nbd_co_send_reply(reply->handle, reply->error, len);
 999
1000     qemu_co_mutex_lock(&client->send_lock);
1001     client->send_coroutine = qemu_coroutine_self();
1002
1003     if (!len) {
1004         ret = nbd_send_reply(client->ioc, reply, errp);
1005     } else {
1006         qio_channel_set_cork(client->ioc, true);
1007         ret = nbd_send_reply(client->ioc, reply, errp);
1008         if (ret == 0) {
1009             ret = nbd_write(client->ioc, req->data, len, errp);
1010             if (ret < 0) {
1011                 ret = -EIO;
1012             }
1013         }
1014         qio_channel_set_cork(client->ioc, false);
1015     }
1016
1017     client->send_coroutine = NULL;
1018     qemu_co_mutex_unlock(&client->send_lock);
1019     return ret;
1020 }
1021
1022 /* nbd_co_receive_request
1023  * Collect a client request. Return 0 if request looks valid, -EIO to drop
1024  * connection right away, and any other negative value to report an error to
1025  * the client (although the caller may still need to disconnect after reporting
1026  * the error).
1027  */
1028 static int nbd_co_receive_request(NBDRequestData *req, NBDRequest *request,
1029                                   Error **errp)
1030 {
1031     NBDClient *client = req->client;
1032
1033     g_assert(qemu_in_coroutine());
1034     assert(client->recv_coroutine == qemu_coroutine_self());
1035     if (nbd_receive_request(client->ioc, request, errp) < 0) {
1036         return -EIO;
1037     }
1038
1039     trace_nbd_co_receive_request_decode_type(request->handle, request->type,
1040                                              nbd_cmd_lookup(request->type));
1041
1042     if (request->type != NBD_CMD_WRITE) {
1043         /* No payload, we are ready to read the next request.  */
1044         req->complete = true;
1045     }
1046
1047     if (request->type == NBD_CMD_DISC) {
1048         /* Special case: we're going to disconnect without a reply,
1049          * whether or not flags, from, or len are bogus */
1050         return -EIO;
1051     }
1052
1053     /* Check for sanity in the parameters, part 1.  Defer as many
1054      * checks as possible until after reading any NBD_CMD_WRITE
1055      * payload, so we can try and keep the connection alive.  */
1056     if ((request->from + request->len) < request->from) {
1057         error_setg(errp,
1058                    "integer overflow detected, you're probably being attacked");
1059         return -EINVAL;
1060     }
1061
1062     if (request->type == NBD_CMD_READ || request->type == NBD_CMD_WRITE) {
1063         if (request->len > NBD_MAX_BUFFER_SIZE) {
1064             error_setg(errp, "len (%" PRIu32" ) is larger than max len (%u)",
1065                        request->len, NBD_MAX_BUFFER_SIZE);
1066             return -EINVAL;
1067         }
1068
1069         req->data = blk_try_blockalign(client->exp->blk, request->len);
1070         if (req->data == NULL) {
1071             error_setg(errp, "No memory");
1072             return -ENOMEM;
1073         }
1074     }
1075     if (request->type == NBD_CMD_WRITE) {
1076         if (nbd_read(client->ioc, req->data, request->len, errp) < 0) {
1077             error_prepend(errp, "reading from socket failed: ");
1078             return -EIO;
1079         }
1080         req->complete = true;
1081
1082         trace_nbd_co_receive_request_payload_received(request->handle,
1083                                                       request->len);
1084     }
1085
1086     /* Sanity checks, part 2. */
1087     if (request->from + request->len > client->exp->size) {
1088         error_setg(errp, "operation past EOF; From: %" PRIu64 ", Len: %" PRIu32
1089                    ", Size: %" PRIu64, request->from, request->len,
1090                    (uint64_t)client->exp->size);
1091         return request->type == NBD_CMD_WRITE ? -ENOSPC : -EINVAL;
1092     }
1093     if (request->flags & ~(NBD_CMD_FLAG_FUA | NBD_CMD_FLAG_NO_HOLE)) {
1094         error_setg(errp, "unsupported flags (got 0x%x)", request->flags);
1095         return -EINVAL;
1096     }
1097     if (request->type != NBD_CMD_WRITE_ZEROES &&
1098         (request->flags & NBD_CMD_FLAG_NO_HOLE)) {
1099         error_setg(errp, "unexpected flags (got 0x%x)", request->flags);
1100         return -EINVAL;
1101     }
1102
1103     return 0;
1104 }
1105
1106 /* Owns a reference to the NBDClient passed as opaque.  */
1107 static coroutine_fn void nbd_trip(void *opaque)
1108 {
1109     NBDClient *client = opaque;
1110     NBDExport *exp = client->exp;
1111     NBDRequestData *req;
1112     NBDRequest request = { 0 };    /* GCC thinks it can be used uninitialized */
1113     NBDReply reply;
1114     int ret;
1115     int flags;
1116     int reply_data_len = 0;
1117     Error *local_err = NULL;
1118
1119     trace_nbd_trip();
1120     if (client->closing) {
1121         nbd_client_put(client);
1122         return;
1123     }
1124
1125     req = nbd_request_get(client);
1126     ret = nbd_co_receive_request(req, &request, &local_err);
1127     client->recv_coroutine = NULL;
1128     nbd_client_receive_next_request(client);
1129     if (ret == -EIO) {
1130         goto disconnect;
1131     }
1132
1133     reply.handle = request.handle;
1134     reply.error = 0;
1135
1136     if (ret < 0) {
1137         reply.error = -ret;
1138         goto reply;
1139     }
1140
1141     if (client->closing) {
1142         /*
1143          * The client may be closed when we are blocked in
1144          * nbd_co_receive_request()
1145          */
1146         goto done;
1147     }
1148
1149     switch (request.type) {
1150     case NBD_CMD_READ:
1151         /* XXX: NBD Protocol only documents use of FUA with WRITE */
1152         if (request.flags & NBD_CMD_FLAG_FUA) {
1153             ret = blk_co_flush(exp->blk);
1154             if (ret < 0) {
1155                 error_setg_errno(&local_err, -ret, "flush failed");
1156                 reply.error = -ret;
1157                 break;
1158             }
1159         }
1160
1161         ret = blk_pread(exp->blk, request.from + exp->dev_offset,
1162                         req->data, request.len);
1163         if (ret < 0) {
1164             error_setg_errno(&local_err, -ret, "reading from file failed");
1165             reply.error = -ret;
1166             break;
1167         }
1168
1169         reply_data_len = request.len;
1170
1171         break;
1172     case NBD_CMD_WRITE:
1173         if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
1174             reply.error = EROFS;
1175             break;
1176         }
1177
1178         flags = 0;
1179         if (request.flags & NBD_CMD_FLAG_FUA) {
1180             flags |= BDRV_REQ_FUA;
1181         }
1182         ret = blk_pwrite(exp->blk, request.from + exp->dev_offset,
1183                          req->data, request.len, flags);
1184         if (ret < 0) {
1185             error_setg_errno(&local_err, -ret, "writing to file failed");
1186             reply.error = -ret;
1187         }
1188
1189         break;
1190     case NBD_CMD_WRITE_ZEROES:
1191         if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
1192             error_setg(&local_err, "Server is read-only, return error");
1193             reply.error = EROFS;
1194             break;
1195         }
1196
1197         flags = 0;
1198         if (request.flags & NBD_CMD_FLAG_FUA) {
1199             flags |= BDRV_REQ_FUA;
1200         }
1201         if (!(request.flags & NBD_CMD_FLAG_NO_HOLE)) {
1202             flags |= BDRV_REQ_MAY_UNMAP;
1203         }
1204         ret = blk_pwrite_zeroes(exp->blk, request.from + exp->dev_offset,
1205                                 request.len, flags);
1206         if (ret < 0) {
1207             error_setg_errno(&local_err, -ret, "writing to file failed");
1208             reply.error = -ret;
1209         }
1210
1211         break;
1212     case NBD_CMD_DISC:
1213         /* unreachable, thanks to special case in nbd_co_receive_request() */
1214         abort();
1215
1216     case NBD_CMD_FLUSH:
1217         ret = blk_co_flush(exp->blk);
1218         if (ret < 0) {
1219             error_setg_errno(&local_err, -ret, "flush failed");
1220             reply.error = -ret;
1221         }
1222
1223         break;
1224     case NBD_CMD_TRIM:
1225         ret = blk_co_pdiscard(exp->blk, request.from + exp->dev_offset,
1226                               request.len);
1227         if (ret < 0) {
1228             error_setg_errno(&local_err, -ret, "discard failed");
1229             reply.error = -ret;
1230         }
1231
1232         break;
1233     default:
1234         error_setg(&local_err, "invalid request type (%" PRIu32 ") received",
1235                    request.type);
1236         reply.error = EINVAL;
1237     }
1238
1239 reply:
1240     if (local_err) {
1241         /* If we are here local_err is not fatal error, already stored in
1242          * reply.error */
1243         error_report_err(local_err);
1244         local_err = NULL;
1245     }
1246
1247     if (nbd_co_send_reply(req, &reply, reply_data_len, &local_err) < 0) {
1248         error_prepend(&local_err, "Failed to send reply: ");
1249         goto disconnect;
1250     }
1251
1252     /* We must disconnect after NBD_CMD_WRITE if we did not
1253      * read the payload.
1254      */
1255     if (!req->complete) {
1256         error_setg(&local_err, "Request handling failed in intermediate state");
1257         goto disconnect;
1258     }
1259
1260 done:
1261     nbd_request_put(req);
1262     nbd_client_put(client);
1263     return;
1264
1265 disconnect:
1266     if (local_err) {
1267         error_reportf_err(local_err, "Disconnect client, due to: ");
1268     }
1269     nbd_request_put(req);
1270     client_close(client, true);
1271     nbd_client_put(client);
1272 }
1273
1274 static void nbd_client_receive_next_request(NBDClient *client)
1275 {
1276     if (!client->recv_coroutine && client->nb_requests < MAX_NBD_REQUESTS) {
1277         nbd_client_get(client);
1278         client->recv_coroutine = qemu_coroutine_create(nbd_trip, client);
1279         aio_co_schedule(client->exp->ctx, client->recv_coroutine);
1280     }
1281 }
1282
1283 static coroutine_fn void nbd_co_client_start(void *opaque)
1284 {
1285     NBDClient *client = opaque;
1286     NBDExport *exp = client->exp;
1287     Error *local_err = NULL;
1288
1289     if (exp) {
1290         nbd_export_get(exp);
1291         QTAILQ_INSERT_TAIL(&exp->clients, client, next);
1292     }
1293     qemu_co_mutex_init(&client->send_lock);
1294
1295     if (nbd_negotiate(client, &local_err)) {
1296         if (local_err) {
1297             error_report_err(local_err);
1298         }
1299         client_close(client, false);
1300         return;
1301     }
1302
1303     nbd_client_receive_next_request(client);
1304 }
1305
1306 /*
1307  * Create a new client listener on the given export @exp, using the
1308  * given channel @sioc.  Begin servicing it in a coroutine.  When the
1309  * connection closes, call @close_fn with an indication of whether the
1310  * client completed negotiation.
1311  */
1312 void nbd_client_new(NBDExport *exp,
1313                     QIOChannelSocket *sioc,
1314                     QCryptoTLSCreds *tlscreds,
1315                     const char *tlsaclname,
1316                     void (*close_fn)(NBDClient *, bool))
1317 {
1318     NBDClient *client;
1319     Coroutine *co;
1320
1321     client = g_malloc0(sizeof(NBDClient));
1322     client->refcount = 1;
1323     client->exp = exp;
1324     client->tlscreds = tlscreds;
1325     if (tlscreds) {
1326         object_ref(OBJECT(client->tlscreds));
1327     }
1328     client->tlsaclname = g_strdup(tlsaclname);
1329     client->sioc = sioc;
1330     object_ref(OBJECT(client->sioc));
1331     client->ioc = QIO_CHANNEL(sioc);
1332     object_ref(OBJECT(client->ioc));
1333     client->close_fn = close_fn;
1334
1335     co = qemu_coroutine_create(nbd_co_client_start, client);
1336     qemu_coroutine_enter(co);
1337 }