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)(NBDClient *client);
  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 static gboolean nbd_negotiate_continue(QIOChannel *ioc,
 108                                        GIOCondition condition,
 109                                        void *opaque)
 110 {
 111     qemu_coroutine_enter(opaque);
 112     return TRUE;
 113 }
 114
 115 static ssize_t nbd_negotiate_read(QIOChannel *ioc, void *buffer, size_t size)
 116 {
 117     ssize_t ret;
 118     guint watch;
 119
 120     assert(qemu_in_coroutine());
 121     /* Negotiation are always in main loop. */
 122     watch = qio_channel_add_watch(ioc,
 123                                   G_IO_IN,
 124                                   nbd_negotiate_continue,
 125                                   qemu_coroutine_self(),
 126                                   NULL);
 127     ret = read_sync(ioc, buffer, size);
 128     g_source_remove(watch);
 129     return ret;
 130
 131 }
 132
 133 static ssize_t nbd_negotiate_write(QIOChannel *ioc, const void *buffer,
 134                                    size_t size)
 135 {
 136     ssize_t ret;
 137     guint watch;
 138
 139     assert(qemu_in_coroutine());
 140     /* Negotiation are always in main loop. */
 141     watch = qio_channel_add_watch(ioc,
 142                                   G_IO_OUT,
 143                                   nbd_negotiate_continue,
 144                                   qemu_coroutine_self(),
 145                                   NULL);
 146     ret = write_sync(ioc, buffer, size);
 147     g_source_remove(watch);
 148     return ret;
 149 }
 150
 151 static ssize_t nbd_negotiate_drop_sync(QIOChannel *ioc, size_t size)
 152 {
 153     ssize_t ret, dropped = size;
 154     uint8_t *buffer = g_malloc(MIN(65536, size));
 155
 156     while (size > 0) {
 157         ret = nbd_negotiate_read(ioc, buffer, MIN(65536, size));
 158         if (ret < 0) {
 159             g_free(buffer);
 160             return ret;
 161         }
 162
 163         assert(ret <= size);
 164         size -= ret;
 165     }
 166
 167     g_free(buffer);
 168     return dropped;
 169 }
 170
 171 /* Basic flow for negotiation
 172
 173    Server         Client
 174    Negotiate
 175
 176    or
 177
 178    Server         Client
 179    Negotiate #1
 180                   Option
 181    Negotiate #2
 182
 183    ----
 184
 185    followed by
 186
 187    Server         Client
 188                   Request
 189    Response
 190                   Request
 191    Response
 192                   ...
 193    ...
 194                   Request (type == 2)
 195
 196 */
 197
 198 /* Send a reply header, including length, but no payload.
 199  * Return -errno on error, 0 on success. */
 200 static int nbd_negotiate_send_rep_len(QIOChannel *ioc, uint32_t type,
 201                                       uint32_t opt, uint32_t len)
 202 {
 203     uint64_t magic;
 204
 205     TRACE("Reply opt=%" PRIx32 " type=%" PRIx32 " len=%" PRIu32,
 206           type, opt, len);
 207
 208     magic = cpu_to_be64(NBD_REP_MAGIC);
 209     if (nbd_negotiate_write(ioc, &magic, sizeof(magic)) != sizeof(magic)) {
 210         LOG("write failed (rep magic)");
 211         return -EINVAL;
 212     }
 213     opt = cpu_to_be32(opt);
 214     if (nbd_negotiate_write(ioc, &opt, sizeof(opt)) != sizeof(opt)) {
 215         LOG("write failed (rep opt)");
 216         return -EINVAL;
 217     }
 218     type = cpu_to_be32(type);
 219     if (nbd_negotiate_write(ioc, &type, sizeof(type)) != sizeof(type)) {
 220         LOG("write failed (rep type)");
 221         return -EINVAL;
 222     }
 223     len = cpu_to_be32(len);
 224     if (nbd_negotiate_write(ioc, &len, sizeof(len)) != sizeof(len)) {
 225         LOG("write failed (rep data length)");
 226         return -EINVAL;
 227     }
 228     return 0;
 229 }
 230
 231 /* Send a reply header with default 0 length.
 232  * Return -errno on error, 0 on success. */
 233 static int nbd_negotiate_send_rep(QIOChannel *ioc, uint32_t type, uint32_t opt)
 234 {
 235     return nbd_negotiate_send_rep_len(ioc, type, opt, 0);
 236 }
 237
 238 /* Send an error reply.
 239  * Return -errno on error, 0 on success. */
 240 static int GCC_FMT_ATTR(4, 5)
 241 nbd_negotiate_send_rep_err(QIOChannel *ioc, uint32_t type,
 242                            uint32_t opt, const char *fmt, ...)
 243 {
 244     va_list va;
 245     char *msg;
 246     int ret;
 247     size_t len;
 248
 249     va_start(va, fmt);
 250     msg = g_strdup_vprintf(fmt, va);
 251     va_end(va);
 252     len = strlen(msg);
 253     assert(len < 4096);
 254     TRACE("sending error message \"%s\"", msg);
 255     ret = nbd_negotiate_send_rep_len(ioc, type, opt, len);
 256     if (ret < 0) {
 257         goto out;
 258     }
 259     if (nbd_negotiate_write(ioc, msg, len) != len) {
 260         LOG("write failed (error message)");
 261         ret = -EIO;
 262     } else {
 263         ret = 0;
 264     }
 265 out:
 266     g_free(msg);
 267     return ret;
 268 }
 269
 270 /* Send a single NBD_REP_SERVER reply to NBD_OPT_LIST, including payload.
 271  * Return -errno on error, 0 on success. */
 272 static int nbd_negotiate_send_rep_list(QIOChannel *ioc, NBDExport *exp)
 273 {
 274     size_t name_len, desc_len;
 275     uint32_t len;
 276     const char *name = exp->name ? exp->name : "";
 277     const char *desc = exp->description ? exp->description : "";
 278     int rc;
 279
 280     TRACE("Advertising export name '%s' description '%s'", name, desc);
 281     name_len = strlen(name);
 282     desc_len = strlen(desc);
 283     len = name_len + desc_len + sizeof(len);
 284     rc = nbd_negotiate_send_rep_len(ioc, NBD_REP_SERVER, NBD_OPT_LIST, len);
 285     if (rc < 0) {
 286         return rc;
 287     }
 288
 289     len = cpu_to_be32(name_len);
 290     if (nbd_negotiate_write(ioc, &len, sizeof(len)) != sizeof(len)) {
 291         LOG("write failed (name length)");
 292         return -EINVAL;
 293     }
 294     if (nbd_negotiate_write(ioc, name, name_len) != name_len) {
 295         LOG("write failed (name buffer)");
 296         return -EINVAL;
 297     }
 298     if (nbd_negotiate_write(ioc, desc, desc_len) != desc_len) {
 299         LOG("write failed (description buffer)");
 300         return -EINVAL;
 301     }
 302     return 0;
 303 }
 304
 305 /* Process the NBD_OPT_LIST command, with a potential series of replies.
 306  * Return -errno on error, 0 on success. */
 307 static int nbd_negotiate_handle_list(NBDClient *client, uint32_t length)
 308 {
 309     NBDExport *exp;
 310
 311     if (length) {
 312         if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
 313             return -EIO;
 314         }
 315         return nbd_negotiate_send_rep_err(client->ioc,
 316                                           NBD_REP_ERR_INVALID, NBD_OPT_LIST,
 317                                           "OPT_LIST should not have length");
 318     }
 319
 320     /* For each export, send a NBD_REP_SERVER reply. */
 321     QTAILQ_FOREACH(exp, &exports, next) {
 322         if (nbd_negotiate_send_rep_list(client->ioc, exp)) {
 323             return -EINVAL;
 324         }
 325     }
 326     /* Finish with a NBD_REP_ACK. */
 327     return nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, NBD_OPT_LIST);
 328 }
 329
 330 static int nbd_negotiate_handle_export_name(NBDClient *client, uint32_t length)
 331 {
 332     int rc = -EINVAL;
 333     char name[NBD_MAX_NAME_SIZE + 1];
 334
 335     /* Client sends:
 336         [20 ..  xx]   export name (length bytes)
 337      */
 338     TRACE("Checking length");
 339     if (length >= sizeof(name)) {
 340         LOG("Bad length received");
 341         goto fail;
 342     }
 343     if (nbd_negotiate_read(client->ioc, name, length) != length) {
 344         LOG("read failed");
 345         goto fail;
 346     }
 347     name[length] = '\0';
 348
 349     TRACE("Client requested export '%s'", name);
 350
 351     client->exp = nbd_export_find(name);
 352     if (!client->exp) {
 353         LOG("export not found");
 354         goto fail;
 355     }
 356
 357     QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
 358     nbd_export_get(client->exp);
 359     rc = 0;
 360 fail:
 361     return rc;
 362 }
 363
 364 /* Handle NBD_OPT_STARTTLS. Return NULL to drop connection, or else the
 365  * new channel for all further (now-encrypted) communication. */
 366 static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client,
 367                                                  uint32_t length)
 368 {
 369     QIOChannel *ioc;
 370     QIOChannelTLS *tioc;
 371     struct NBDTLSHandshakeData data = { 0 };
 372
 373     TRACE("Setting up TLS");
 374     ioc = client->ioc;
 375     if (length) {
 376         if (nbd_negotiate_drop_sync(ioc, length) != length) {
 377             return NULL;
 378         }
 379         nbd_negotiate_send_rep_err(ioc, NBD_REP_ERR_INVALID, NBD_OPT_STARTTLS,
 380                                    "OPT_STARTTLS should not have length");
 381         return NULL;
 382     }
 383
 384     if (nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK,
 385                                NBD_OPT_STARTTLS) < 0) {
 386         return NULL;
 387     }
 388
 389     tioc = qio_channel_tls_new_server(ioc,
 390                                       client->tlscreds,
 391                                       client->tlsaclname,
 392                                       NULL);
 393     if (!tioc) {
 394         return NULL;
 395     }
 396
 397     qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-server-tls");
 398     TRACE("Starting TLS handshake");
 399     data.loop = g_main_loop_new(g_main_context_default(), FALSE);
 400     qio_channel_tls_handshake(tioc,
 401                               nbd_tls_handshake,
 402                               &data,
 403                               NULL);
 404
 405     if (!data.complete) {
 406         g_main_loop_run(data.loop);
 407     }
 408     g_main_loop_unref(data.loop);
 409     if (data.error) {
 410         object_unref(OBJECT(tioc));
 411         error_free(data.error);
 412         return NULL;
 413     }
 414
 415     return QIO_CHANNEL(tioc);
 416 }
 417
 418
 419 /* Process all NBD_OPT_* client option commands.
 420  * Return -errno on error, 0 on success. */
 421 static int nbd_negotiate_options(NBDClient *client)
 422 {
 423     uint32_t flags;
 424     bool fixedNewstyle = false;
 425
 426     /* Client sends:
 427         [ 0 ..   3]   client flags
 428
 429         [ 0 ..   7]   NBD_OPTS_MAGIC
 430         [ 8 ..  11]   NBD option
 431         [12 ..  15]   Data length
 432         ...           Rest of request
 433
 434         [ 0 ..   7]   NBD_OPTS_MAGIC
 435         [ 8 ..  11]   Second NBD option
 436         [12 ..  15]   Data length
 437         ...           Rest of request
 438     */
 439
 440     if (nbd_negotiate_read(client->ioc, &flags, sizeof(flags)) !=
 441         sizeof(flags)) {
 442         LOG("read failed");
 443         return -EIO;
 444     }
 445     TRACE("Checking client flags");
 446     be32_to_cpus(&flags);
 447     if (flags & NBD_FLAG_C_FIXED_NEWSTYLE) {
 448         TRACE("Client supports fixed newstyle handshake");
 449         fixedNewstyle = true;
 450         flags &= ~NBD_FLAG_C_FIXED_NEWSTYLE;
 451     }
 452     if (flags & NBD_FLAG_C_NO_ZEROES) {
 453         TRACE("Client supports no zeroes at handshake end");
 454         client->no_zeroes = true;
 455         flags &= ~NBD_FLAG_C_NO_ZEROES;
 456     }
 457     if (flags != 0) {
 458         TRACE("Unknown client flags 0x%" PRIx32 " received", flags);
 459         return -EIO;
 460     }
 461
 462     while (1) {
 463         int ret;
 464         uint32_t clientflags, length;
 465         uint64_t magic;
 466
 467         if (nbd_negotiate_read(client->ioc, &magic, sizeof(magic)) !=
 468             sizeof(magic)) {
 469             LOG("read failed");
 470             return -EINVAL;
 471         }
 472         TRACE("Checking opts magic");
 473         if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) {
 474             LOG("Bad magic received");
 475             return -EINVAL;
 476         }
 477
 478         if (nbd_negotiate_read(client->ioc, &clientflags,
 479                                sizeof(clientflags)) != sizeof(clientflags)) {
 480             LOG("read failed");
 481             return -EINVAL;
 482         }
 483         clientflags = be32_to_cpu(clientflags);
 484
 485         if (nbd_negotiate_read(client->ioc, &length, sizeof(length)) !=
 486             sizeof(length)) {
 487             LOG("read failed");
 488             return -EINVAL;
 489         }
 490         length = be32_to_cpu(length);
 491
 492         TRACE("Checking option 0x%" PRIx32, clientflags);
 493         if (client->tlscreds &&
 494             client->ioc == (QIOChannel *)client->sioc) {
 495             QIOChannel *tioc;
 496             if (!fixedNewstyle) {
 497                 TRACE("Unsupported option 0x%" PRIx32, clientflags);
 498                 return -EINVAL;
 499             }
 500             switch (clientflags) {
 501             case NBD_OPT_STARTTLS:
 502                 tioc = nbd_negotiate_handle_starttls(client, length);
 503                 if (!tioc) {
 504                     return -EIO;
 505                 }
 506                 object_unref(OBJECT(client->ioc));
 507                 client->ioc = QIO_CHANNEL(tioc);
 508                 break;
 509
 510             case NBD_OPT_EXPORT_NAME:
 511                 /* No way to return an error to client, so drop connection */
 512                 TRACE("Option 0x%x not permitted before TLS", clientflags);
 513                 return -EINVAL;
 514
 515             default:
 516                 if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
 517                     return -EIO;
 518                 }
 519                 ret = nbd_negotiate_send_rep_err(client->ioc,
 520                                                  NBD_REP_ERR_TLS_REQD,
 521                                                  clientflags,
 522                                                  "Option 0x%" PRIx32
 523                                                  "not permitted before TLS",
 524                                                  clientflags);
 525                 if (ret < 0) {
 526                     return ret;
 527                 }
 528                 /* Let the client keep trying, unless they asked to quit */
 529                 if (clientflags == NBD_OPT_ABORT) {
 530                     return -EINVAL;
 531                 }
 532                 break;
 533             }
 534         } else if (fixedNewstyle) {
 535             switch (clientflags) {
 536             case NBD_OPT_LIST:
 537                 ret = nbd_negotiate_handle_list(client, length);
 538                 if (ret < 0) {
 539                     return ret;
 540                 }
 541                 break;
 542
 543             case NBD_OPT_ABORT:
 544                 /* NBD spec says we must try to reply before
 545                  * disconnecting, but that we must also tolerate
 546                  * guests that don't wait for our reply. */
 547                 nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, clientflags);
 548                 return -EINVAL;
 549
 550             case NBD_OPT_EXPORT_NAME:
 551                 return nbd_negotiate_handle_export_name(client, length);
 552
 553             case NBD_OPT_STARTTLS:
 554                 if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
 555                     return -EIO;
 556                 }
 557                 if (client->tlscreds) {
 558                     ret = nbd_negotiate_send_rep_err(client->ioc,
 559                                                      NBD_REP_ERR_INVALID,
 560                                                      clientflags,
 561                                                      "TLS already enabled");
 562                 } else {
 563                     ret = nbd_negotiate_send_rep_err(client->ioc,
 564                                                      NBD_REP_ERR_POLICY,
 565                                                      clientflags,
 566                                                      "TLS not configured");
 567                 }
 568                 if (ret < 0) {
 569                     return ret;
 570                 }
 571                 break;
 572             default:
 573                 if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
 574                     return -EIO;
 575                 }
 576                 ret = nbd_negotiate_send_rep_err(client->ioc,
 577                                                  NBD_REP_ERR_UNSUP,
 578                                                  clientflags,
 579                                                  "Unsupported option 0x%"
 580                                                  PRIx32,
 581                                                  clientflags);
 582                 if (ret < 0) {
 583                     return ret;
 584                 }
 585                 break;
 586             }
 587         } else {
 588             /*
 589              * If broken new-style we should drop the connection
 590              * for anything except NBD_OPT_EXPORT_NAME
 591              */
 592             switch (clientflags) {
 593             case NBD_OPT_EXPORT_NAME:
 594                 return nbd_negotiate_handle_export_name(client, length);
 595
 596             default:
 597                 TRACE("Unsupported option 0x%" PRIx32, clientflags);
 598                 return -EINVAL;
 599             }
 600         }
 601     }
 602 }
 603
 604 typedef struct {
 605     NBDClient *client;
 606     Coroutine *co;
 607 } NBDClientNewData;
 608
 609 static coroutine_fn int nbd_negotiate(NBDClientNewData *data)
 610 {
 611     NBDClient *client = data->client;
 612     char buf[8 + 8 + 8 + 128];
 613     int rc;
 614     const uint16_t myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM |
 615                               NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA |
 616                               NBD_FLAG_SEND_WRITE_ZEROES);
 617     bool oldStyle;
 618     size_t len;
 619
 620     /* Old style negotiation header without options
 621         [ 0 ..   7]   passwd       ("NBDMAGIC")
 622         [ 8 ..  15]   magic        (NBD_CLIENT_MAGIC)
 623         [16 ..  23]   size
 624         [24 ..  25]   server flags (0)
 625         [26 ..  27]   export flags
 626         [28 .. 151]   reserved     (0)
 627
 628        New style negotiation header with options
 629         [ 0 ..   7]   passwd       ("NBDMAGIC")
 630         [ 8 ..  15]   magic        (NBD_OPTS_MAGIC)
 631         [16 ..  17]   server flags (0)
 632         ....options sent....
 633         [18 ..  25]   size
 634         [26 ..  27]   export flags
 635         [28 .. 151]   reserved     (0, omit if no_zeroes)
 636      */
 637
 638     qio_channel_set_blocking(client->ioc, false, NULL);
 639     rc = -EINVAL;
 640
 641     TRACE("Beginning negotiation.");
 642     memset(buf, 0, sizeof(buf));
 643     memcpy(buf, "NBDMAGIC", 8);
 644
 645     oldStyle = client->exp != NULL && !client->tlscreds;
 646     if (oldStyle) {
 647         TRACE("advertising size %" PRIu64 " and flags %x",
 648               client->exp->size, client->exp->nbdflags | myflags);
 649         stq_be_p(buf + 8, NBD_CLIENT_MAGIC);
 650         stq_be_p(buf + 16, client->exp->size);
 651         stw_be_p(buf + 26, client->exp->nbdflags | myflags);
 652     } else {
 653         stq_be_p(buf + 8, NBD_OPTS_MAGIC);
 654         stw_be_p(buf + 16, NBD_FLAG_FIXED_NEWSTYLE | NBD_FLAG_NO_ZEROES);
 655     }
 656
 657     if (oldStyle) {
 658         if (client->tlscreds) {
 659             TRACE("TLS cannot be enabled with oldstyle protocol");
 660             goto fail;
 661         }
 662         if (nbd_negotiate_write(client->ioc, buf, sizeof(buf)) != sizeof(buf)) {
 663             LOG("write failed");
 664             goto fail;
 665         }
 666     } else {
 667         if (nbd_negotiate_write(client->ioc, buf, 18) != 18) {
 668             LOG("write failed");
 669             goto fail;
 670         }
 671         rc = nbd_negotiate_options(client);
 672         if (rc != 0) {
 673             LOG("option negotiation failed");
 674             goto fail;
 675         }
 676
 677         TRACE("advertising size %" PRIu64 " and flags %x",
 678               client->exp->size, client->exp->nbdflags | myflags);
 679         stq_be_p(buf + 18, client->exp->size);
 680         stw_be_p(buf + 26, client->exp->nbdflags | myflags);
 681         len = client->no_zeroes ? 10 : sizeof(buf) - 18;
 682         if (nbd_negotiate_write(client->ioc, buf + 18, len) != len) {
 683             LOG("write failed");
 684             goto fail;
 685         }
 686     }
 687
 688     TRACE("Negotiation succeeded.");
 689     rc = 0;
 690 fail:
 691     return rc;
 692 }
 693
 694 static ssize_t nbd_receive_request(QIOChannel *ioc, NBDRequest *request)
 695 {
 696     uint8_t buf[NBD_REQUEST_SIZE];
 697     uint32_t magic;
 698     ssize_t ret;
 699
 700     ret = read_sync(ioc, buf, sizeof(buf));
 701     if (ret < 0) {
 702         return ret;
 703     }
 704
 705     if (ret != sizeof(buf)) {
 706         LOG("read failed");
 707         return -EINVAL;
 708     }
 709
 710     /* Request
 711        [ 0 ..  3]   magic   (NBD_REQUEST_MAGIC)
 712        [ 4 ..  5]   flags   (NBD_CMD_FLAG_FUA, ...)
 713        [ 6 ..  7]   type    (NBD_CMD_READ, ...)
 714        [ 8 .. 15]   handle
 715        [16 .. 23]   from
 716        [24 .. 27]   len
 717      */
 718
 719     magic = ldl_be_p(buf);
 720     request->flags  = lduw_be_p(buf + 4);
 721     request->type   = lduw_be_p(buf + 6);
 722     request->handle = ldq_be_p(buf + 8);
 723     request->from   = ldq_be_p(buf + 16);
 724     request->len    = ldl_be_p(buf + 24);
 725
 726     TRACE("Got request: { magic = 0x%" PRIx32 ", .flags = %" PRIx16
 727           ", .type = %" PRIx16 ", from = %" PRIu64 ", len = %" PRIu32 " }",
 728           magic, request->flags, request->type, request->from, request->len);
 729
 730     if (magic != NBD_REQUEST_MAGIC) {
 731         LOG("invalid magic (got 0x%" PRIx32 ")", magic);
 732         return -EINVAL;
 733     }
 734     return 0;
 735 }
 736
 737 static ssize_t nbd_send_reply(QIOChannel *ioc, NBDReply *reply)
 738 {
 739     uint8_t buf[NBD_REPLY_SIZE];
 740     ssize_t ret;
 741
 742     reply->error = system_errno_to_nbd_errno(reply->error);
 743
 744     TRACE("Sending response to client: { .error = %" PRId32
 745           ", handle = %" PRIu64 " }",
 746           reply->error, reply->handle);
 747
 748     /* Reply
 749        [ 0 ..  3]    magic   (NBD_REPLY_MAGIC)
 750        [ 4 ..  7]    error   (0 == no error)
 751        [ 7 .. 15]    handle
 752      */
 753     stl_be_p(buf, NBD_REPLY_MAGIC);
 754     stl_be_p(buf + 4, reply->error);
 755     stq_be_p(buf + 8, reply->handle);
 756
 757     ret = write_sync(ioc, buf, sizeof(buf));
 758     if (ret < 0) {
 759         return ret;
 760     }
 761
 762     if (ret != sizeof(buf)) {
 763         LOG("writing to socket failed");
 764         return -EINVAL;
 765     }
 766     return 0;
 767 }
 768
 769 #define MAX_NBD_REQUESTS 16
 770
 771 void nbd_client_get(NBDClient *client)
 772 {
 773     client->refcount++;
 774 }
 775
 776 void nbd_client_put(NBDClient *client)
 777 {
 778     if (--client->refcount == 0) {
 779         /* The last reference should be dropped by client->close,
 780          * which is called by client_close.
 781          */
 782         assert(client->closing);
 783
 784         qio_channel_detach_aio_context(client->ioc);
 785         object_unref(OBJECT(client->sioc));
 786         object_unref(OBJECT(client->ioc));
 787         if (client->tlscreds) {
 788             object_unref(OBJECT(client->tlscreds));
 789         }
 790         g_free(client->tlsaclname);
 791         if (client->exp) {
 792             QTAILQ_REMOVE(&client->exp->clients, client, next);
 793             nbd_export_put(client->exp);
 794         }
 795         g_free(client);
 796     }
 797 }
 798
 799 static void client_close(NBDClient *client)
 800 {
 801     if (client->closing) {
 802         return;
 803     }
 804
 805     client->closing = true;
 806
 807     /* Force requests to finish.  They will drop their own references,
 808      * then we'll close the socket and free the NBDClient.
 809      */
 810     qio_channel_shutdown(client->ioc, QIO_CHANNEL_SHUTDOWN_BOTH,
 811                          NULL);
 812
 813     /* Also tell the client, so that they release their reference.  */
 814     if (client->close) {
 815         client->close(client);
 816     }
 817 }
 818
 819 static NBDRequestData *nbd_request_get(NBDClient *client)
 820 {
 821     NBDRequestData *req;
 822
 823     assert(client->nb_requests <= MAX_NBD_REQUESTS - 1);
 824     client->nb_requests++;
 825
 826     req = g_new0(NBDRequestData, 1);
 827     nbd_client_get(client);
 828     req->client = client;
 829     return req;
 830 }
 831
 832 static void nbd_request_put(NBDRequestData *req)
 833 {
 834     NBDClient *client = req->client;
 835
 836     if (req->data) {
 837         qemu_vfree(req->data);
 838     }
 839     g_free(req);
 840
 841     client->nb_requests--;
 842     nbd_client_receive_next_request(client);
 843
 844     nbd_client_put(client);
 845 }
 846
 847 static void blk_aio_attached(AioContext *ctx, void *opaque)
 848 {
 849     NBDExport *exp = opaque;
 850     NBDClient *client;
 851
 852     TRACE("Export %s: Attaching clients to AIO context %p\n", exp->name, ctx);
 853
 854     exp->ctx = ctx;
 855
 856     QTAILQ_FOREACH(client, &exp->clients, next) {
 857         qio_channel_attach_aio_context(client->ioc, ctx);
 858         if (client->recv_coroutine) {
 859             aio_co_schedule(ctx, client->recv_coroutine);
 860         }
 861         if (client->send_coroutine) {
 862             aio_co_schedule(ctx, client->send_coroutine);
 863         }
 864     }
 865 }
 866
 867 static void blk_aio_detach(void *opaque)
 868 {
 869     NBDExport *exp = opaque;
 870     NBDClient *client;
 871
 872     TRACE("Export %s: Detaching clients from AIO context %p\n", exp->name, exp->ctx);
 873
 874     QTAILQ_FOREACH(client, &exp->clients, next) {
 875         qio_channel_detach_aio_context(client->ioc);
 876     }
 877
 878     exp->ctx = NULL;
 879 }
 880
 881 static void nbd_eject_notifier(Notifier *n, void *data)
 882 {
 883     NBDExport *exp = container_of(n, NBDExport, eject_notifier);
 884     nbd_export_close(exp);
 885 }
 886
 887 NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset, off_t size,
 888                           uint16_t nbdflags, void (*close)(NBDExport *),
 889                           bool writethrough, BlockBackend *on_eject_blk,
 890                           Error **errp)
 891 {
 892     BlockBackend *blk;
 893     NBDExport *exp = g_malloc0(sizeof(NBDExport));
 894     int ret;
 895
 896     /* FIXME Use real permissions */
 897     blk = blk_new(0, BLK_PERM_ALL);
 898     ret = blk_insert_bs(blk, bs, errp);
 899     if (ret < 0) {
 900         goto fail;
 901     }
 902     blk_set_enable_write_cache(blk, !writethrough);
 903
 904     exp->refcount = 1;
 905     QTAILQ_INIT(&exp->clients);
 906     exp->blk = blk;
 907     exp->dev_offset = dev_offset;
 908     exp->nbdflags = nbdflags;
 909     exp->size = size < 0 ? blk_getlength(blk) : size;
 910     if (exp->size < 0) {
 911         error_setg_errno(errp, -exp->size,
 912                          "Failed to determine the NBD export's length");
 913         goto fail;
 914     }
 915     exp->size -= exp->size % BDRV_SECTOR_SIZE;
 916
 917     exp->close = close;
 918     exp->ctx = blk_get_aio_context(blk);
 919     blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
 920
 921     if (on_eject_blk) {
 922         blk_ref(on_eject_blk);
 923         exp->eject_notifier_blk = on_eject_blk;
 924         exp->eject_notifier.notify = nbd_eject_notifier;
 925         blk_add_remove_bs_notifier(on_eject_blk, &exp->eject_notifier);
 926     }
 927
 928     /*
 929      * NBD exports are used for non-shared storage migration.  Make sure
 930      * that BDRV_O_INACTIVE is cleared and the image is ready for write
 931      * access since the export could be available before migration handover.
 932      */
 933     aio_context_acquire(exp->ctx);
 934     blk_invalidate_cache(blk, NULL);
 935     aio_context_release(exp->ctx);
 936     return exp;
 937
 938 fail:
 939     blk_unref(blk);
 940     g_free(exp);
 941     return NULL;
 942 }
 943
 944 NBDExport *nbd_export_find(const char *name)
 945 {
 946     NBDExport *exp;
 947     QTAILQ_FOREACH(exp, &exports, next) {
 948         if (strcmp(name, exp->name) == 0) {
 949             return exp;
 950         }
 951     }
 952
 953     return NULL;
 954 }
 955
 956 void nbd_export_set_name(NBDExport *exp, const char *name)
 957 {
 958     if (exp->name == name) {
 959         return;
 960     }
 961
 962     nbd_export_get(exp);
 963     if (exp->name != NULL) {
 964         g_free(exp->name);
 965         exp->name = NULL;
 966         QTAILQ_REMOVE(&exports, exp, next);
 967         nbd_export_put(exp);
 968     }
 969     if (name != NULL) {
 970         nbd_export_get(exp);
 971         exp->name = g_strdup(name);
 972         QTAILQ_INSERT_TAIL(&exports, exp, next);
 973     }
 974     nbd_export_put(exp);
 975 }
 976
 977 void nbd_export_set_description(NBDExport *exp, const char *description)
 978 {
 979     g_free(exp->description);
 980     exp->description = g_strdup(description);
 981 }
 982
 983 void nbd_export_close(NBDExport *exp)
 984 {
 985     NBDClient *client, *next;
 986
 987     nbd_export_get(exp);
 988     QTAILQ_FOREACH_SAFE(client, &exp->clients, next, next) {
 989         client_close(client);
 990     }
 991     nbd_export_set_name(exp, NULL);
 992     nbd_export_set_description(exp, NULL);
 993     nbd_export_put(exp);
 994 }
 995
 996 void nbd_export_get(NBDExport *exp)
 997 {
 998     assert(exp->refcount > 0);
 999     exp->refcount++;
1000 }
1001
1002 void nbd_export_put(NBDExport *exp)
1003 {
1004     assert(exp->refcount > 0);
1005     if (exp->refcount == 1) {
1006         nbd_export_close(exp);
1007     }
1008
1009     if (--exp->refcount == 0) {
1010         assert(exp->name == NULL);
1011         assert(exp->description == NULL);
1012
1013         if (exp->close) {
1014             exp->close(exp);
1015         }
1016
1017         if (exp->blk) {
1018             if (exp->eject_notifier_blk) {
1019                 notifier_remove(&exp->eject_notifier);
1020                 blk_unref(exp->eject_notifier_blk);
1021             }
1022             blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
1023                                             blk_aio_detach, exp);
1024             blk_unref(exp->blk);
1025             exp->blk = NULL;
1026         }
1027
1028         g_free(exp);
1029     }
1030 }
1031
1032 BlockBackend *nbd_export_get_blockdev(NBDExport *exp)
1033 {
1034     return exp->blk;
1035 }
1036
1037 void nbd_export_close_all(void)
1038 {
1039     NBDExport *exp, *next;
1040
1041     QTAILQ_FOREACH_SAFE(exp, &exports, next, next) {
1042         nbd_export_close(exp);
1043     }
1044 }
1045
1046 static ssize_t nbd_co_send_reply(NBDRequestData *req, NBDReply *reply,
1047                                  int len)
1048 {
1049     NBDClient *client = req->client;
1050     ssize_t rc, ret;
1051
1052     g_assert(qemu_in_coroutine());
1053     qemu_co_mutex_lock(&client->send_lock);
1054     client->send_coroutine = qemu_coroutine_self();
1055
1056     if (!len) {
1057         rc = nbd_send_reply(client->ioc, reply);
1058     } else {
1059         qio_channel_set_cork(client->ioc, true);
1060         rc = nbd_send_reply(client->ioc, reply);
1061         if (rc >= 0) {
1062             ret = write_sync(client->ioc, req->data, len);
1063             if (ret != len) {
1064                 rc = -EIO;
1065             }
1066         }
1067         qio_channel_set_cork(client->ioc, false);
1068     }
1069
1070     client->send_coroutine = NULL;
1071     qemu_co_mutex_unlock(&client->send_lock);
1072     return rc;
1073 }
1074
1075 /* Collect a client request.  Return 0 if request looks valid, -EAGAIN
1076  * to keep trying the collection, -EIO to drop connection right away,
1077  * and any other negative value to report an error to the client
1078  * (although the caller may still need to disconnect after reporting
1079  * the error).  */
1080 static ssize_t nbd_co_receive_request(NBDRequestData *req,
1081                                       NBDRequest *request)
1082 {
1083     NBDClient *client = req->client;
1084     ssize_t rc;
1085
1086     g_assert(qemu_in_coroutine());
1087     assert(client->recv_coroutine == qemu_coroutine_self());
1088     rc = nbd_receive_request(client->ioc, request);
1089     if (rc < 0) {
1090         if (rc != -EAGAIN) {
1091             rc = -EIO;
1092         }
1093         goto out;
1094     }
1095
1096     TRACE("Decoding type");
1097
1098     if (request->type != NBD_CMD_WRITE) {
1099         /* No payload, we are ready to read the next request.  */
1100         req->complete = true;
1101     }
1102
1103     if (request->type == NBD_CMD_DISC) {
1104         /* Special case: we're going to disconnect without a reply,
1105          * whether or not flags, from, or len are bogus */
1106         TRACE("Request type is DISCONNECT");
1107         rc = -EIO;
1108         goto out;
1109     }
1110
1111     /* Check for sanity in the parameters, part 1.  Defer as many
1112      * checks as possible until after reading any NBD_CMD_WRITE
1113      * payload, so we can try and keep the connection alive.  */
1114     if ((request->from + request->len) < request->from) {
1115         LOG("integer overflow detected, you're probably being attacked");
1116         rc = -EINVAL;
1117         goto out;
1118     }
1119
1120     if (request->type == NBD_CMD_READ || request->type == NBD_CMD_WRITE) {
1121         if (request->len > NBD_MAX_BUFFER_SIZE) {
1122             LOG("len (%" PRIu32" ) is larger than max len (%u)",
1123                 request->len, NBD_MAX_BUFFER_SIZE);
1124             rc = -EINVAL;
1125             goto out;
1126         }
1127
1128         req->data = blk_try_blockalign(client->exp->blk, request->len);
1129         if (req->data == NULL) {
1130             rc = -ENOMEM;
1131             goto out;
1132         }
1133     }
1134     if (request->type == NBD_CMD_WRITE) {
1135         TRACE("Reading %" PRIu32 " byte(s)", request->len);
1136
1137         if (read_sync(client->ioc, req->data, request->len) != request->len) {
1138             LOG("reading from socket failed");
1139             rc = -EIO;
1140             goto out;
1141         }
1142         req->complete = true;
1143     }
1144
1145     /* Sanity checks, part 2. */
1146     if (request->from + request->len > client->exp->size) {
1147         LOG("operation past EOF; From: %" PRIu64 ", Len: %" PRIu32
1148             ", Size: %" PRIu64, request->from, request->len,
1149             (uint64_t)client->exp->size);
1150         rc = request->type == NBD_CMD_WRITE ? -ENOSPC : -EINVAL;
1151         goto out;
1152     }
1153     if (request->flags & ~(NBD_CMD_FLAG_FUA | NBD_CMD_FLAG_NO_HOLE)) {
1154         LOG("unsupported flags (got 0x%x)", request->flags);
1155         rc = -EINVAL;
1156         goto out;
1157     }
1158     if (request->type != NBD_CMD_WRITE_ZEROES &&
1159         (request->flags & NBD_CMD_FLAG_NO_HOLE)) {
1160         LOG("unexpected flags (got 0x%x)", request->flags);
1161         rc = -EINVAL;
1162         goto out;
1163     }
1164
1165     rc = 0;
1166
1167 out:
1168     client->recv_coroutine = NULL;
1169     nbd_client_receive_next_request(client);
1170
1171     return rc;
1172 }
1173
1174 /* Owns a reference to the NBDClient passed as opaque.  */
1175 static coroutine_fn void nbd_trip(void *opaque)
1176 {
1177     NBDClient *client = opaque;
1178     NBDExport *exp = client->exp;
1179     NBDRequestData *req;
1180     NBDRequest request = { 0 };    /* GCC thinks it can be used uninitialized */
1181     NBDReply reply;
1182     ssize_t ret;
1183     int flags;
1184
1185     TRACE("Reading request.");
1186     if (client->closing) {
1187         nbd_client_put(client);
1188         return;
1189     }
1190
1191     req = nbd_request_get(client);
1192     ret = nbd_co_receive_request(req, &request);
1193     if (ret == -EAGAIN) {
1194         goto done;
1195     }
1196     if (ret == -EIO) {
1197         goto out;
1198     }
1199
1200     reply.handle = request.handle;
1201     reply.error = 0;
1202
1203     if (ret < 0) {
1204         reply.error = -ret;
1205         goto error_reply;
1206     }
1207
1208     if (client->closing) {
1209         /*
1210          * The client may be closed when we are blocked in
1211          * nbd_co_receive_request()
1212          */
1213         goto done;
1214     }
1215
1216     switch (request.type) {
1217     case NBD_CMD_READ:
1218         TRACE("Request type is READ");
1219
1220         /* XXX: NBD Protocol only documents use of FUA with WRITE */
1221         if (request.flags & NBD_CMD_FLAG_FUA) {
1222             ret = blk_co_flush(exp->blk);
1223             if (ret < 0) {
1224                 LOG("flush failed");
1225                 reply.error = -ret;
1226                 goto error_reply;
1227             }
1228         }
1229
1230         ret = blk_pread(exp->blk, request.from + exp->dev_offset,
1231                         req->data, request.len);
1232         if (ret < 0) {
1233             LOG("reading from file failed");
1234             reply.error = -ret;
1235             goto error_reply;
1236         }
1237
1238         TRACE("Read %" PRIu32" byte(s)", request.len);
1239         if (nbd_co_send_reply(req, &reply, request.len) < 0)
1240             goto out;
1241         break;
1242     case NBD_CMD_WRITE:
1243         TRACE("Request type is WRITE");
1244
1245         if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
1246             TRACE("Server is read-only, return error");
1247             reply.error = EROFS;
1248             goto error_reply;
1249         }
1250
1251         TRACE("Writing to device");
1252
1253         flags = 0;
1254         if (request.flags & NBD_CMD_FLAG_FUA) {
1255             flags |= BDRV_REQ_FUA;
1256         }
1257         ret = blk_pwrite(exp->blk, request.from + exp->dev_offset,
1258                          req->data, request.len, flags);
1259         if (ret < 0) {
1260             LOG("writing to file failed");
1261             reply.error = -ret;
1262             goto error_reply;
1263         }
1264
1265         if (nbd_co_send_reply(req, &reply, 0) < 0) {
1266             goto out;
1267         }
1268         break;
1269
1270     case NBD_CMD_WRITE_ZEROES:
1271         TRACE("Request type is WRITE_ZEROES");
1272
1273         if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
1274             TRACE("Server is read-only, return error");
1275             reply.error = EROFS;
1276             goto error_reply;
1277         }
1278
1279         TRACE("Writing to device");
1280
1281         flags = 0;
1282         if (request.flags & NBD_CMD_FLAG_FUA) {
1283             flags |= BDRV_REQ_FUA;
1284         }
1285         if (!(request.flags & NBD_CMD_FLAG_NO_HOLE)) {
1286             flags |= BDRV_REQ_MAY_UNMAP;
1287         }
1288         ret = blk_pwrite_zeroes(exp->blk, request.from + exp->dev_offset,
1289                                 request.len, flags);
1290         if (ret < 0) {
1291             LOG("writing to file failed");
1292             reply.error = -ret;
1293             goto error_reply;
1294         }
1295
1296         if (nbd_co_send_reply(req, &reply, 0) < 0) {
1297             goto out;
1298         }
1299         break;
1300
1301     case NBD_CMD_DISC:
1302         /* unreachable, thanks to special case in nbd_co_receive_request() */
1303         abort();
1304
1305     case NBD_CMD_FLUSH:
1306         TRACE("Request type is FLUSH");
1307
1308         ret = blk_co_flush(exp->blk);
1309         if (ret < 0) {
1310             LOG("flush failed");
1311             reply.error = -ret;
1312         }
1313         if (nbd_co_send_reply(req, &reply, 0) < 0) {
1314             goto out;
1315         }
1316         break;
1317     case NBD_CMD_TRIM:
1318         TRACE("Request type is TRIM");
1319         ret = blk_co_pdiscard(exp->blk, request.from + exp->dev_offset,
1320                               request.len);
1321         if (ret < 0) {
1322             LOG("discard failed");
1323             reply.error = -ret;
1324         }
1325         if (nbd_co_send_reply(req, &reply, 0) < 0) {
1326             goto out;
1327         }
1328         break;
1329     default:
1330         LOG("invalid request type (%" PRIu32 ") received", request.type);
1331         reply.error = EINVAL;
1332     error_reply:
1333         /* We must disconnect after NBD_CMD_WRITE if we did not
1334          * read the payload.
1335          */
1336         if (nbd_co_send_reply(req, &reply, 0) < 0 || !req->complete) {
1337             goto out;
1338         }
1339         break;
1340     }
1341
1342     TRACE("Request/Reply complete");
1343
1344 done:
1345     nbd_request_put(req);
1346     nbd_client_put(client);
1347     return;
1348
1349 out:
1350     nbd_request_put(req);
1351     client_close(client);
1352     nbd_client_put(client);
1353 }
1354
1355 static void nbd_client_receive_next_request(NBDClient *client)
1356 {
1357     if (!client->recv_coroutine && client->nb_requests < MAX_NBD_REQUESTS) {
1358         nbd_client_get(client);
1359         client->recv_coroutine = qemu_coroutine_create(nbd_trip, client);
1360         aio_co_schedule(client->exp->ctx, client->recv_coroutine);
1361     }
1362 }
1363
1364 static coroutine_fn void nbd_co_client_start(void *opaque)
1365 {
1366     NBDClientNewData *data = opaque;
1367     NBDClient *client = data->client;
1368     NBDExport *exp = client->exp;
1369
1370     if (exp) {
1371         nbd_export_get(exp);
1372     }
1373     if (nbd_negotiate(data)) {
1374         client_close(client);
1375         goto out;
1376     }
1377     qemu_co_mutex_init(&client->send_lock);
1378
1379     if (exp) {
1380         QTAILQ_INSERT_TAIL(&exp->clients, client, next);
1381     }
1382
1383     nbd_client_receive_next_request(client);
1384
1385 out:
1386     g_free(data);
1387 }
1388
1389 void nbd_client_new(NBDExport *exp,
1390                     QIOChannelSocket *sioc,
1391                     QCryptoTLSCreds *tlscreds,
1392                     const char *tlsaclname,
1393                     void (*close_fn)(NBDClient *))
1394 {
1395     NBDClient *client;
1396     NBDClientNewData *data = g_new(NBDClientNewData, 1);
1397
1398     client = g_malloc0(sizeof(NBDClient));
1399     client->refcount = 1;
1400     client->exp = exp;
1401     client->tlscreds = tlscreds;
1402     if (tlscreds) {
1403         object_ref(OBJECT(client->tlscreds));
1404     }
1405     client->tlsaclname = g_strdup(tlsaclname);
1406     client->sioc = sioc;
1407     object_ref(OBJECT(client->sioc));
1408     client->ioc = QIO_CHANNEL(sioc);
1409     object_ref(OBJECT(client->ioc));
1410     client->close = close_fn;
1411
1412     data->client = client;
1413     data->co = qemu_coroutine_create(nbd_co_client_start, data);
1414     qemu_coroutine_enter(data->co);
1415 }