1 /* 2 * Copyright (C) 2016-2019 Red Hat, Inc. 3 * Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws> 4 * 5 * Network Block Device Client 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 "qemu/queue.h" 23 #include "trace.h" 24 #include "nbd-internal.h" 25 #include "qemu/cutils.h" 26 27 /* Definitions for opaque data types */ 28 29 static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports); 30 31 /* That's all folks */ 32 33 /* Basic flow for negotiation 34 35 Server Client 36 Negotiate 37 38 or 39 40 Server Client 41 Negotiate #1 42 Option 43 Negotiate #2 44 45 ---- 46 47 followed by 48 49 Server Client 50 Request 51 Response 52 Request 53 Response 54 ... 55 ... 56 Request (type == 2) 57 58 */ 59 60 /* Send an option request. 61 * 62 * The request is for option @opt, with @data containing @len bytes of 63 * additional payload for the request (@len may be -1 to treat @data as 64 * a C string; and @data may be NULL if @len is 0). 65 * Return 0 if successful, -1 with errp set if it is impossible to 66 * continue. */ 67 static int nbd_send_option_request(QIOChannel *ioc, uint32_t opt, 68 uint32_t len, const char *data, 69 Error **errp) 70 { 71 NBDOption req; 72 QEMU_BUILD_BUG_ON(sizeof(req) != 16); 73 74 if (len == -1) { 75 req.length = len = strlen(data); 76 } 77 trace_nbd_send_option_request(opt, nbd_opt_lookup(opt), len); 78 79 stq_be_p(&req.magic, NBD_OPTS_MAGIC); 80 stl_be_p(&req.option, opt); 81 stl_be_p(&req.length, len); 82 83 if (nbd_write(ioc, &req, sizeof(req), errp) < 0) { 84 error_prepend(errp, "Failed to send option request header: "); 85 return -1; 86 } 87 88 if (len && nbd_write(ioc, (char *) data, len, errp) < 0) { 89 error_prepend(errp, "Failed to send option request data: "); 90 return -1; 91 } 92 93 return 0; 94 } 95 96 /* Send NBD_OPT_ABORT as a courtesy to let the server know that we are 97 * not going to attempt further negotiation. */ 98 static void nbd_send_opt_abort(QIOChannel *ioc) 99 { 100 /* Technically, a compliant server is supposed to reply to us; but 101 * older servers disconnected instead. At any rate, we're allowed 102 * to disconnect without waiting for the server reply, so we don't 103 * even care if the request makes it to the server, let alone 104 * waiting around for whether the server replies. */ 105 nbd_send_option_request(ioc, NBD_OPT_ABORT, 0, NULL, NULL); 106 } 107 108 109 /* Receive the header of an option reply, which should match the given 110 * opt. Read through the length field, but NOT the length bytes of 111 * payload. Return 0 if successful, -1 with errp set if it is 112 * impossible to continue. */ 113 static int nbd_receive_option_reply(QIOChannel *ioc, uint32_t opt, 114 NBDOptionReply *reply, Error **errp) 115 { 116 QEMU_BUILD_BUG_ON(sizeof(*reply) != 20); 117 if (nbd_read(ioc, reply, sizeof(*reply), "option reply", errp) < 0) { 118 nbd_send_opt_abort(ioc); 119 return -1; 120 } 121 reply->magic = be64_to_cpu(reply->magic); 122 reply->option = be32_to_cpu(reply->option); 123 reply->type = be32_to_cpu(reply->type); 124 reply->length = be32_to_cpu(reply->length); 125 126 trace_nbd_receive_option_reply(reply->option, nbd_opt_lookup(reply->option), 127 reply->type, nbd_rep_lookup(reply->type), 128 reply->length); 129 130 if (reply->magic != NBD_REP_MAGIC) { 131 error_setg(errp, "Unexpected option reply magic"); 132 nbd_send_opt_abort(ioc); 133 return -1; 134 } 135 if (reply->option != opt) { 136 error_setg(errp, "Unexpected option type %u (%s), expected %u (%s)", 137 reply->option, nbd_opt_lookup(reply->option), 138 opt, nbd_opt_lookup(opt)); 139 nbd_send_opt_abort(ioc); 140 return -1; 141 } 142 return 0; 143 } 144 145 /* 146 * If reply represents success, return 1 without further action. If 147 * reply represents an error, consume the optional payload of the 148 * packet on ioc. Then return 0 for unsupported (so the client can 149 * fall back to other approaches), where @strict determines if only 150 * ERR_UNSUP or all errors fit that category, or -1 with errp set for 151 * other errors. 152 */ 153 static int nbd_handle_reply_err(QIOChannel *ioc, NBDOptionReply *reply, 154 bool strict, Error **errp) 155 { 156 g_autofree char *msg = NULL; 157 158 if (!(reply->type & (1 << 31))) { 159 return 1; 160 } 161 162 if (reply->length) { 163 if (reply->length > NBD_MAX_BUFFER_SIZE) { 164 error_setg(errp, "server error %" PRIu32 165 " (%s) message is too long", 166 reply->type, nbd_rep_lookup(reply->type)); 167 goto err; 168 } 169 msg = g_malloc(reply->length + 1); 170 if (nbd_read(ioc, msg, reply->length, NULL, errp) < 0) { 171 error_prepend(errp, "Failed to read option error %" PRIu32 172 " (%s) message: ", 173 reply->type, nbd_rep_lookup(reply->type)); 174 goto err; 175 } 176 msg[reply->length] = '\0'; 177 trace_nbd_server_error_msg(reply->type, 178 nbd_reply_type_lookup(reply->type), msg); 179 } 180 181 if (reply->type == NBD_REP_ERR_UNSUP || !strict) { 182 trace_nbd_reply_err_ignored(reply->option, 183 nbd_opt_lookup(reply->option), 184 reply->type, nbd_rep_lookup(reply->type)); 185 return 0; 186 } 187 188 switch (reply->type) { 189 case NBD_REP_ERR_POLICY: 190 error_setg(errp, "Denied by server for option %" PRIu32 " (%s)", 191 reply->option, nbd_opt_lookup(reply->option)); 192 break; 193 194 case NBD_REP_ERR_INVALID: 195 error_setg(errp, "Invalid parameters for option %" PRIu32 " (%s)", 196 reply->option, nbd_opt_lookup(reply->option)); 197 break; 198 199 case NBD_REP_ERR_PLATFORM: 200 error_setg(errp, "Server lacks support for option %" PRIu32 " (%s)", 201 reply->option, nbd_opt_lookup(reply->option)); 202 break; 203 204 case NBD_REP_ERR_TLS_REQD: 205 error_setg(errp, "TLS negotiation required before option %" PRIu32 206 " (%s)", reply->option, nbd_opt_lookup(reply->option)); 207 error_append_hint(errp, "Did you forget a valid tls-creds?\n"); 208 break; 209 210 case NBD_REP_ERR_UNKNOWN: 211 error_setg(errp, "Requested export not available"); 212 break; 213 214 case NBD_REP_ERR_SHUTDOWN: 215 error_setg(errp, "Server shutting down before option %" PRIu32 " (%s)", 216 reply->option, nbd_opt_lookup(reply->option)); 217 break; 218 219 case NBD_REP_ERR_BLOCK_SIZE_REQD: 220 error_setg(errp, "Server requires INFO_BLOCK_SIZE for option %" PRIu32 221 " (%s)", reply->option, nbd_opt_lookup(reply->option)); 222 break; 223 224 default: 225 error_setg(errp, "Unknown error code when asking for option %" PRIu32 226 " (%s)", reply->option, nbd_opt_lookup(reply->option)); 227 break; 228 } 229 230 if (msg) { 231 error_append_hint(errp, "server reported: %s\n", msg); 232 } 233 234 err: 235 nbd_send_opt_abort(ioc); 236 return -1; 237 } 238 239 /* nbd_receive_list: 240 * Process another portion of the NBD_OPT_LIST reply, populating any 241 * name received into *@name. If @description is non-NULL, and the 242 * server provided a description, that is also populated. The caller 243 * must eventually call g_free() on success. 244 * Returns 1 if name and description were set and iteration must continue, 245 * 0 if iteration is complete (including if OPT_LIST unsupported), 246 * -1 with @errp set if an unrecoverable error occurred. 247 */ 248 static int nbd_receive_list(QIOChannel *ioc, char **name, char **description, 249 Error **errp) 250 { 251 NBDOptionReply reply; 252 uint32_t len; 253 uint32_t namelen; 254 g_autofree char *local_name = NULL; 255 g_autofree char *local_desc = NULL; 256 int error; 257 258 if (nbd_receive_option_reply(ioc, NBD_OPT_LIST, &reply, errp) < 0) { 259 return -1; 260 } 261 error = nbd_handle_reply_err(ioc, &reply, true, errp); 262 if (error <= 0) { 263 return error; 264 } 265 len = reply.length; 266 267 if (reply.type == NBD_REP_ACK) { 268 if (len != 0) { 269 error_setg(errp, "length too long for option end"); 270 nbd_send_opt_abort(ioc); 271 return -1; 272 } 273 return 0; 274 } else if (reply.type != NBD_REP_SERVER) { 275 error_setg(errp, "Unexpected reply type %u (%s), expected %u (%s)", 276 reply.type, nbd_rep_lookup(reply.type), 277 NBD_REP_SERVER, nbd_rep_lookup(NBD_REP_SERVER)); 278 nbd_send_opt_abort(ioc); 279 return -1; 280 } 281 282 if (len < sizeof(namelen) || len > NBD_MAX_BUFFER_SIZE) { 283 error_setg(errp, "incorrect option length %" PRIu32, len); 284 nbd_send_opt_abort(ioc); 285 return -1; 286 } 287 if (nbd_read32(ioc, &namelen, "option name length", errp) < 0) { 288 nbd_send_opt_abort(ioc); 289 return -1; 290 } 291 len -= sizeof(namelen); 292 if (len < namelen || namelen > NBD_MAX_STRING_SIZE) { 293 error_setg(errp, "incorrect name length in server's list response"); 294 nbd_send_opt_abort(ioc); 295 return -1; 296 } 297 298 local_name = g_malloc(namelen + 1); 299 if (nbd_read(ioc, local_name, namelen, "export name", errp) < 0) { 300 nbd_send_opt_abort(ioc); 301 return -1; 302 } 303 local_name[namelen] = '\0'; 304 len -= namelen; 305 if (len) { 306 if (len > NBD_MAX_STRING_SIZE) { 307 error_setg(errp, "incorrect description length in server's " 308 "list response"); 309 nbd_send_opt_abort(ioc); 310 return -1; 311 } 312 local_desc = g_malloc(len + 1); 313 if (nbd_read(ioc, local_desc, len, "export description", errp) < 0) { 314 nbd_send_opt_abort(ioc); 315 return -1; 316 } 317 local_desc[len] = '\0'; 318 } 319 320 trace_nbd_receive_list(local_name, local_desc ?: ""); 321 *name = g_steal_pointer(&local_name); 322 if (description) { 323 *description = g_steal_pointer(&local_desc); 324 } 325 return 1; 326 } 327 328 329 /* 330 * nbd_opt_info_or_go: 331 * Send option for NBD_OPT_INFO or NBD_OPT_GO and parse the reply. 332 * Returns -1 if the option proves the export @info->name cannot be 333 * used, 0 if the option is unsupported (fall back to NBD_OPT_LIST and 334 * NBD_OPT_EXPORT_NAME in that case), and > 0 if the export is good to 335 * go (with the rest of @info populated). 336 */ 337 static int nbd_opt_info_or_go(QIOChannel *ioc, uint32_t opt, 338 NBDExportInfo *info, Error **errp) 339 { 340 NBDOptionReply reply; 341 uint32_t len = strlen(info->name); 342 uint16_t type; 343 int error; 344 char *buf; 345 346 /* The protocol requires that the server send NBD_INFO_EXPORT with 347 * a non-zero flags (at least NBD_FLAG_HAS_FLAGS must be set); so 348 * flags still 0 is a witness of a broken server. */ 349 info->flags = 0; 350 351 assert(opt == NBD_OPT_GO || opt == NBD_OPT_INFO); 352 trace_nbd_opt_info_go_start(nbd_opt_lookup(opt), info->name); 353 buf = g_malloc(4 + len + 2 + 2 * info->request_sizes + 1); 354 stl_be_p(buf, len); 355 memcpy(buf + 4, info->name, len); 356 /* At most one request, everything else up to server */ 357 stw_be_p(buf + 4 + len, info->request_sizes); 358 if (info->request_sizes) { 359 stw_be_p(buf + 4 + len + 2, NBD_INFO_BLOCK_SIZE); 360 } 361 error = nbd_send_option_request(ioc, opt, 362 4 + len + 2 + 2 * info->request_sizes, 363 buf, errp); 364 g_free(buf); 365 if (error < 0) { 366 return -1; 367 } 368 369 while (1) { 370 if (nbd_receive_option_reply(ioc, opt, &reply, errp) < 0) { 371 return -1; 372 } 373 error = nbd_handle_reply_err(ioc, &reply, true, errp); 374 if (error <= 0) { 375 return error; 376 } 377 len = reply.length; 378 379 if (reply.type == NBD_REP_ACK) { 380 /* 381 * Server is done sending info, and moved into transmission 382 * phase for NBD_OPT_GO, but make sure it sent flags 383 */ 384 if (len) { 385 error_setg(errp, "server sent invalid NBD_REP_ACK"); 386 return -1; 387 } 388 if (!info->flags) { 389 error_setg(errp, "broken server omitted NBD_INFO_EXPORT"); 390 return -1; 391 } 392 trace_nbd_opt_info_go_success(nbd_opt_lookup(opt)); 393 return 1; 394 } 395 if (reply.type != NBD_REP_INFO) { 396 error_setg(errp, "unexpected reply type %u (%s), expected %u (%s)", 397 reply.type, nbd_rep_lookup(reply.type), 398 NBD_REP_INFO, nbd_rep_lookup(NBD_REP_INFO)); 399 nbd_send_opt_abort(ioc); 400 return -1; 401 } 402 if (len < sizeof(type)) { 403 error_setg(errp, "NBD_REP_INFO length %" PRIu32 " is too short", 404 len); 405 nbd_send_opt_abort(ioc); 406 return -1; 407 } 408 if (nbd_read16(ioc, &type, "info type", errp) < 0) { 409 nbd_send_opt_abort(ioc); 410 return -1; 411 } 412 len -= sizeof(type); 413 switch (type) { 414 case NBD_INFO_EXPORT: 415 if (len != sizeof(info->size) + sizeof(info->flags)) { 416 error_setg(errp, "remaining export info len %" PRIu32 417 " is unexpected size", len); 418 nbd_send_opt_abort(ioc); 419 return -1; 420 } 421 if (nbd_read64(ioc, &info->size, "info size", errp) < 0) { 422 nbd_send_opt_abort(ioc); 423 return -1; 424 } 425 if (nbd_read16(ioc, &info->flags, "info flags", errp) < 0) { 426 nbd_send_opt_abort(ioc); 427 return -1; 428 } 429 if (info->min_block && 430 !QEMU_IS_ALIGNED(info->size, info->min_block)) { 431 error_setg(errp, "export size %" PRIu64 " is not multiple of " 432 "minimum block size %" PRIu32, info->size, 433 info->min_block); 434 nbd_send_opt_abort(ioc); 435 return -1; 436 } 437 trace_nbd_receive_negotiate_size_flags(info->size, info->flags); 438 break; 439 440 case NBD_INFO_BLOCK_SIZE: 441 if (len != sizeof(info->min_block) * 3) { 442 error_setg(errp, "remaining export info len %" PRIu32 443 " is unexpected size", len); 444 nbd_send_opt_abort(ioc); 445 return -1; 446 } 447 if (nbd_read32(ioc, &info->min_block, "info minimum block size", 448 errp) < 0) { 449 nbd_send_opt_abort(ioc); 450 return -1; 451 } 452 if (!is_power_of_2(info->min_block)) { 453 error_setg(errp, "server minimum block size %" PRIu32 454 " is not a power of two", info->min_block); 455 nbd_send_opt_abort(ioc); 456 return -1; 457 } 458 if (nbd_read32(ioc, &info->opt_block, "info preferred block size", 459 errp) < 0) 460 { 461 nbd_send_opt_abort(ioc); 462 return -1; 463 } 464 if (!is_power_of_2(info->opt_block) || 465 info->opt_block < info->min_block) { 466 error_setg(errp, "server preferred block size %" PRIu32 467 " is not valid", info->opt_block); 468 nbd_send_opt_abort(ioc); 469 return -1; 470 } 471 if (nbd_read32(ioc, &info->max_block, "info maximum block size", 472 errp) < 0) 473 { 474 nbd_send_opt_abort(ioc); 475 return -1; 476 } 477 if (info->max_block < info->min_block) { 478 error_setg(errp, "server maximum block size %" PRIu32 479 " is not valid", info->max_block); 480 nbd_send_opt_abort(ioc); 481 return -1; 482 } 483 trace_nbd_opt_info_block_size(info->min_block, info->opt_block, 484 info->max_block); 485 break; 486 487 default: 488 /* 489 * Not worth the bother to check if NBD_INFO_NAME or 490 * NBD_INFO_DESCRIPTION exceed NBD_MAX_STRING_SIZE. 491 */ 492 trace_nbd_opt_info_unknown(type, nbd_info_lookup(type)); 493 if (nbd_drop(ioc, len, errp) < 0) { 494 error_prepend(errp, "Failed to read info payload: "); 495 nbd_send_opt_abort(ioc); 496 return -1; 497 } 498 break; 499 } 500 } 501 } 502 503 /* Return -1 on failure, 0 if wantname is an available export. */ 504 static int nbd_receive_query_exports(QIOChannel *ioc, 505 const char *wantname, 506 Error **errp) 507 { 508 bool list_empty = true; 509 bool found_export = false; 510 511 trace_nbd_receive_query_exports_start(wantname); 512 if (nbd_send_option_request(ioc, NBD_OPT_LIST, 0, NULL, errp) < 0) { 513 return -1; 514 } 515 516 while (1) { 517 char *name; 518 int ret = nbd_receive_list(ioc, &name, NULL, errp); 519 520 if (ret < 0) { 521 /* Server gave unexpected reply */ 522 return -1; 523 } else if (ret == 0) { 524 /* Done iterating. */ 525 if (list_empty) { 526 /* 527 * We don't have enough context to tell a server that 528 * sent an empty list apart from a server that does 529 * not support the list command; but as this function 530 * is just used to trigger a nicer error message 531 * before trying NBD_OPT_EXPORT_NAME, assume the 532 * export is available. 533 */ 534 return 0; 535 } else if (!found_export) { 536 error_setg(errp, "No export with name '%s' available", 537 wantname); 538 nbd_send_opt_abort(ioc); 539 return -1; 540 } 541 trace_nbd_receive_query_exports_success(wantname); 542 return 0; 543 } 544 list_empty = false; 545 if (!strcmp(name, wantname)) { 546 found_export = true; 547 } 548 g_free(name); 549 } 550 } 551 552 /* 553 * nbd_request_simple_option: Send an option request, and parse the reply. 554 * @strict controls whether ERR_UNSUP or all errors produce 0 status. 555 * return 1 for successful negotiation, 556 * 0 if operation is unsupported, 557 * -1 with errp set for any other error 558 */ 559 static int nbd_request_simple_option(QIOChannel *ioc, int opt, bool strict, 560 Error **errp) 561 { 562 NBDOptionReply reply; 563 int error; 564 565 if (nbd_send_option_request(ioc, opt, 0, NULL, errp) < 0) { 566 return -1; 567 } 568 569 if (nbd_receive_option_reply(ioc, opt, &reply, errp) < 0) { 570 return -1; 571 } 572 error = nbd_handle_reply_err(ioc, &reply, strict, errp); 573 if (error <= 0) { 574 return error; 575 } 576 577 if (reply.type != NBD_REP_ACK) { 578 error_setg(errp, "Server answered option %d (%s) with unexpected " 579 "reply %" PRIu32 " (%s)", opt, nbd_opt_lookup(opt), 580 reply.type, nbd_rep_lookup(reply.type)); 581 nbd_send_opt_abort(ioc); 582 return -1; 583 } 584 585 if (reply.length != 0) { 586 error_setg(errp, "Option %d ('%s') response length is %" PRIu32 587 " (it should be zero)", opt, nbd_opt_lookup(opt), 588 reply.length); 589 nbd_send_opt_abort(ioc); 590 return -1; 591 } 592 593 return 1; 594 } 595 596 static QIOChannel *nbd_receive_starttls(QIOChannel *ioc, 597 QCryptoTLSCreds *tlscreds, 598 const char *hostname, Error **errp) 599 { 600 int ret; 601 QIOChannelTLS *tioc; 602 struct NBDTLSHandshakeData data = { 0 }; 603 604 ret = nbd_request_simple_option(ioc, NBD_OPT_STARTTLS, true, errp); 605 if (ret <= 0) { 606 if (ret == 0) { 607 error_setg(errp, "Server don't support STARTTLS option"); 608 nbd_send_opt_abort(ioc); 609 } 610 return NULL; 611 } 612 613 trace_nbd_receive_starttls_new_client(); 614 tioc = qio_channel_tls_new_client(ioc, tlscreds, hostname, errp); 615 if (!tioc) { 616 return NULL; 617 } 618 qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-client-tls"); 619 data.loop = g_main_loop_new(g_main_context_default(), FALSE); 620 trace_nbd_receive_starttls_tls_handshake(); 621 qio_channel_tls_handshake(tioc, 622 nbd_tls_handshake, 623 &data, 624 NULL, 625 NULL); 626 627 if (!data.complete) { 628 g_main_loop_run(data.loop); 629 } 630 g_main_loop_unref(data.loop); 631 if (data.error) { 632 error_propagate(errp, data.error); 633 object_unref(OBJECT(tioc)); 634 return NULL; 635 } 636 637 return QIO_CHANNEL(tioc); 638 } 639 640 /* 641 * nbd_send_meta_query: 642 * Send 0 or 1 set/list meta context queries. 643 * Return 0 on success, -1 with errp set for any error 644 */ 645 static int nbd_send_meta_query(QIOChannel *ioc, uint32_t opt, 646 const char *export, const char *query, 647 Error **errp) 648 { 649 int ret; 650 uint32_t export_len = strlen(export); 651 uint32_t queries = !!query; 652 uint32_t query_len = 0; 653 uint32_t data_len; 654 char *data; 655 char *p; 656 657 data_len = sizeof(export_len) + export_len + sizeof(queries); 658 assert(export_len <= NBD_MAX_STRING_SIZE); 659 if (query) { 660 query_len = strlen(query); 661 data_len += sizeof(query_len) + query_len; 662 assert(query_len <= NBD_MAX_STRING_SIZE); 663 } else { 664 assert(opt == NBD_OPT_LIST_META_CONTEXT); 665 } 666 p = data = g_malloc(data_len); 667 668 trace_nbd_opt_meta_request(nbd_opt_lookup(opt), query ?: "(all)", export); 669 stl_be_p(p, export_len); 670 memcpy(p += sizeof(export_len), export, export_len); 671 stl_be_p(p += export_len, queries); 672 if (query) { 673 stl_be_p(p += sizeof(queries), query_len); 674 memcpy(p += sizeof(query_len), query, query_len); 675 } 676 677 ret = nbd_send_option_request(ioc, opt, data_len, data, errp); 678 g_free(data); 679 return ret; 680 } 681 682 /* 683 * nbd_receive_one_meta_context: 684 * Called in a loop to receive and trace one set/list meta context reply. 685 * Pass non-NULL @name or @id to collect results back to the caller, which 686 * must eventually call g_free(). 687 * return 1 if name is set and iteration must continue, 688 * 0 if iteration is complete (including if option is unsupported), 689 * -1 with errp set for any error 690 */ 691 static int nbd_receive_one_meta_context(QIOChannel *ioc, 692 uint32_t opt, 693 char **name, 694 uint32_t *id, 695 Error **errp) 696 { 697 int ret; 698 NBDOptionReply reply; 699 char *local_name = NULL; 700 uint32_t local_id; 701 702 if (nbd_receive_option_reply(ioc, opt, &reply, errp) < 0) { 703 return -1; 704 } 705 706 ret = nbd_handle_reply_err(ioc, &reply, false, errp); 707 if (ret <= 0) { 708 return ret; 709 } 710 711 if (reply.type == NBD_REP_ACK) { 712 if (reply.length != 0) { 713 error_setg(errp, "Unexpected length to ACK response"); 714 nbd_send_opt_abort(ioc); 715 return -1; 716 } 717 return 0; 718 } else if (reply.type != NBD_REP_META_CONTEXT) { 719 error_setg(errp, "Unexpected reply type %u (%s), expected %u (%s)", 720 reply.type, nbd_rep_lookup(reply.type), 721 NBD_REP_META_CONTEXT, nbd_rep_lookup(NBD_REP_META_CONTEXT)); 722 nbd_send_opt_abort(ioc); 723 return -1; 724 } 725 726 if (reply.length <= sizeof(local_id) || 727 reply.length > NBD_MAX_BUFFER_SIZE) { 728 error_setg(errp, "Failed to negotiate meta context, server " 729 "answered with unexpected length %" PRIu32, 730 reply.length); 731 nbd_send_opt_abort(ioc); 732 return -1; 733 } 734 735 if (nbd_read32(ioc, &local_id, "context id", errp) < 0) { 736 return -1; 737 } 738 739 reply.length -= sizeof(local_id); 740 local_name = g_malloc(reply.length + 1); 741 if (nbd_read(ioc, local_name, reply.length, "context name", errp) < 0) { 742 g_free(local_name); 743 return -1; 744 } 745 local_name[reply.length] = '\0'; 746 trace_nbd_opt_meta_reply(nbd_opt_lookup(opt), local_name, local_id); 747 748 if (name) { 749 *name = local_name; 750 } else { 751 g_free(local_name); 752 } 753 if (id) { 754 *id = local_id; 755 } 756 return 1; 757 } 758 759 /* 760 * nbd_negotiate_simple_meta_context: 761 * Request the server to set the meta context for export @info->name 762 * using @info->x_dirty_bitmap with a fallback to "base:allocation", 763 * setting @info->context_id to the resulting id. Fail if the server 764 * responds with more than one context or with a context different 765 * than the query. 766 * return 1 for successful negotiation, 767 * 0 if operation is unsupported, 768 * -1 with errp set for any other error 769 */ 770 static int nbd_negotiate_simple_meta_context(QIOChannel *ioc, 771 NBDExportInfo *info, 772 Error **errp) 773 { 774 /* 775 * TODO: Removing the x_dirty_bitmap hack will mean refactoring 776 * this function to request and store ids for multiple contexts 777 * (both base:allocation and a dirty bitmap), at which point this 778 * function should lose the term _simple. 779 */ 780 int ret; 781 const char *context = info->x_dirty_bitmap ?: "base:allocation"; 782 bool received = false; 783 char *name = NULL; 784 785 if (nbd_send_meta_query(ioc, NBD_OPT_SET_META_CONTEXT, 786 info->name, context, errp) < 0) { 787 return -1; 788 } 789 790 ret = nbd_receive_one_meta_context(ioc, NBD_OPT_SET_META_CONTEXT, 791 &name, &info->context_id, errp); 792 if (ret < 0) { 793 return -1; 794 } 795 if (ret == 1) { 796 if (strcmp(context, name)) { 797 error_setg(errp, "Failed to negotiate meta context '%s', server " 798 "answered with different context '%s'", context, 799 name); 800 g_free(name); 801 nbd_send_opt_abort(ioc); 802 return -1; 803 } 804 g_free(name); 805 received = true; 806 807 ret = nbd_receive_one_meta_context(ioc, NBD_OPT_SET_META_CONTEXT, 808 NULL, NULL, errp); 809 if (ret < 0) { 810 return -1; 811 } 812 } 813 if (ret != 0) { 814 error_setg(errp, "Server answered with more than one context"); 815 nbd_send_opt_abort(ioc); 816 return -1; 817 } 818 return received; 819 } 820 821 /* 822 * nbd_list_meta_contexts: 823 * Request the server to list all meta contexts for export @info->name. 824 * return 0 if list is complete (even if empty), 825 * -1 with errp set for any error 826 */ 827 static int nbd_list_meta_contexts(QIOChannel *ioc, 828 NBDExportInfo *info, 829 Error **errp) 830 { 831 int ret; 832 int seen_any = false; 833 int seen_qemu = false; 834 835 if (nbd_send_meta_query(ioc, NBD_OPT_LIST_META_CONTEXT, 836 info->name, NULL, errp) < 0) { 837 return -1; 838 } 839 840 while (1) { 841 char *context; 842 843 ret = nbd_receive_one_meta_context(ioc, NBD_OPT_LIST_META_CONTEXT, 844 &context, NULL, errp); 845 if (ret == 0 && seen_any && !seen_qemu) { 846 /* 847 * Work around qemu 3.0 bug: the server forgot to send 848 * "qemu:" replies to 0 queries. If we saw at least one 849 * reply (probably base:allocation), but none of them were 850 * qemu:, then run a more specific query to make sure. 851 */ 852 seen_qemu = true; 853 if (nbd_send_meta_query(ioc, NBD_OPT_LIST_META_CONTEXT, 854 info->name, "qemu:", errp) < 0) { 855 return -1; 856 } 857 continue; 858 } 859 if (ret <= 0) { 860 return ret; 861 } 862 seen_any = true; 863 seen_qemu |= strstart(context, "qemu:", NULL); 864 info->contexts = g_renew(char *, info->contexts, ++info->n_contexts); 865 info->contexts[info->n_contexts - 1] = context; 866 } 867 } 868 869 /* 870 * nbd_start_negotiate: 871 * Start the handshake to the server. After a positive return, the server 872 * is ready to accept additional NBD_OPT requests. 873 * Returns: negative errno: failure talking to server 874 * 0: server is oldstyle, must call nbd_negotiate_finish_oldstyle 875 * 1: server is newstyle, but can only accept EXPORT_NAME 876 * 2: server is newstyle, but lacks structured replies 877 * 3: server is newstyle and set up for structured replies 878 */ 879 static int nbd_start_negotiate(AioContext *aio_context, QIOChannel *ioc, 880 QCryptoTLSCreds *tlscreds, 881 const char *hostname, QIOChannel **outioc, 882 bool structured_reply, bool *zeroes, 883 Error **errp) 884 { 885 uint64_t magic; 886 887 trace_nbd_start_negotiate(tlscreds, hostname ? hostname : "<null>"); 888 889 if (zeroes) { 890 *zeroes = true; 891 } 892 if (outioc) { 893 *outioc = NULL; 894 } 895 if (tlscreds && !outioc) { 896 error_setg(errp, "Output I/O channel required for TLS"); 897 return -EINVAL; 898 } 899 900 if (nbd_read64(ioc, &magic, "initial magic", errp) < 0) { 901 return -EINVAL; 902 } 903 trace_nbd_receive_negotiate_magic(magic); 904 905 if (magic != NBD_INIT_MAGIC) { 906 error_setg(errp, "Bad initial magic received: 0x%" PRIx64, magic); 907 return -EINVAL; 908 } 909 910 if (nbd_read64(ioc, &magic, "server magic", errp) < 0) { 911 return -EINVAL; 912 } 913 trace_nbd_receive_negotiate_magic(magic); 914 915 if (magic == NBD_OPTS_MAGIC) { 916 uint32_t clientflags = 0; 917 uint16_t globalflags; 918 bool fixedNewStyle = false; 919 920 if (nbd_read16(ioc, &globalflags, "server flags", errp) < 0) { 921 return -EINVAL; 922 } 923 trace_nbd_receive_negotiate_server_flags(globalflags); 924 if (globalflags & NBD_FLAG_FIXED_NEWSTYLE) { 925 fixedNewStyle = true; 926 clientflags |= NBD_FLAG_C_FIXED_NEWSTYLE; 927 } 928 if (globalflags & NBD_FLAG_NO_ZEROES) { 929 if (zeroes) { 930 *zeroes = false; 931 } 932 clientflags |= NBD_FLAG_C_NO_ZEROES; 933 } 934 /* client requested flags */ 935 clientflags = cpu_to_be32(clientflags); 936 if (nbd_write(ioc, &clientflags, sizeof(clientflags), errp) < 0) { 937 error_prepend(errp, "Failed to send clientflags field: "); 938 return -EINVAL; 939 } 940 if (tlscreds) { 941 if (fixedNewStyle) { 942 *outioc = nbd_receive_starttls(ioc, tlscreds, hostname, errp); 943 if (!*outioc) { 944 return -EINVAL; 945 } 946 ioc = *outioc; 947 if (aio_context) { 948 qio_channel_set_blocking(ioc, false, NULL); 949 qio_channel_attach_aio_context(ioc, aio_context); 950 } 951 } else { 952 error_setg(errp, "Server does not support STARTTLS"); 953 return -EINVAL; 954 } 955 } 956 if (fixedNewStyle) { 957 int result = 0; 958 959 if (structured_reply) { 960 result = nbd_request_simple_option(ioc, 961 NBD_OPT_STRUCTURED_REPLY, 962 false, errp); 963 if (result < 0) { 964 return -EINVAL; 965 } 966 } 967 return 2 + result; 968 } else { 969 return 1; 970 } 971 } else if (magic == NBD_CLIENT_MAGIC) { 972 if (tlscreds) { 973 error_setg(errp, "Server does not support STARTTLS"); 974 return -EINVAL; 975 } 976 return 0; 977 } else { 978 error_setg(errp, "Bad server magic received: 0x%" PRIx64, magic); 979 return -EINVAL; 980 } 981 } 982 983 /* 984 * nbd_negotiate_finish_oldstyle: 985 * Populate @info with the size and export flags from an oldstyle server, 986 * but does not consume 124 bytes of reserved zero padding. 987 * Returns 0 on success, -1 with @errp set on failure 988 */ 989 static int nbd_negotiate_finish_oldstyle(QIOChannel *ioc, NBDExportInfo *info, 990 Error **errp) 991 { 992 uint32_t oldflags; 993 994 if (nbd_read64(ioc, &info->size, "export length", errp) < 0) { 995 return -EINVAL; 996 } 997 998 if (nbd_read32(ioc, &oldflags, "export flags", errp) < 0) { 999 return -EINVAL; 1000 } 1001 if (oldflags & ~0xffff) { 1002 error_setg(errp, "Unexpected export flags %0x" PRIx32, oldflags); 1003 return -EINVAL; 1004 } 1005 info->flags = oldflags; 1006 return 0; 1007 } 1008 1009 /* 1010 * nbd_receive_negotiate: 1011 * Connect to server, complete negotiation, and move into transmission phase. 1012 * Returns: negative errno: failure talking to server 1013 * 0: server is connected 1014 */ 1015 int nbd_receive_negotiate(AioContext *aio_context, QIOChannel *ioc, 1016 QCryptoTLSCreds *tlscreds, 1017 const char *hostname, QIOChannel **outioc, 1018 NBDExportInfo *info, Error **errp) 1019 { 1020 int result; 1021 bool zeroes; 1022 bool base_allocation = info->base_allocation; 1023 1024 assert(info->name && strlen(info->name) <= NBD_MAX_STRING_SIZE); 1025 trace_nbd_receive_negotiate_name(info->name); 1026 1027 result = nbd_start_negotiate(aio_context, ioc, tlscreds, hostname, outioc, 1028 info->structured_reply, &zeroes, errp); 1029 1030 info->structured_reply = false; 1031 info->base_allocation = false; 1032 if (tlscreds && *outioc) { 1033 ioc = *outioc; 1034 } 1035 1036 switch (result) { 1037 case 3: /* newstyle, with structured replies */ 1038 info->structured_reply = true; 1039 if (base_allocation) { 1040 result = nbd_negotiate_simple_meta_context(ioc, info, errp); 1041 if (result < 0) { 1042 return -EINVAL; 1043 } 1044 info->base_allocation = result == 1; 1045 } 1046 /* fall through */ 1047 case 2: /* newstyle, try OPT_GO */ 1048 /* Try NBD_OPT_GO first - if it works, we are done (it 1049 * also gives us a good message if the server requires 1050 * TLS). If it is not available, fall back to 1051 * NBD_OPT_LIST for nicer error messages about a missing 1052 * export, then use NBD_OPT_EXPORT_NAME. */ 1053 result = nbd_opt_info_or_go(ioc, NBD_OPT_GO, info, errp); 1054 if (result < 0) { 1055 return -EINVAL; 1056 } 1057 if (result > 0) { 1058 return 0; 1059 } 1060 /* Check our desired export is present in the 1061 * server export list. Since NBD_OPT_EXPORT_NAME 1062 * cannot return an error message, running this 1063 * query gives us better error reporting if the 1064 * export name is not available. 1065 */ 1066 if (nbd_receive_query_exports(ioc, info->name, errp) < 0) { 1067 return -EINVAL; 1068 } 1069 /* fall through */ 1070 case 1: /* newstyle, but limited to EXPORT_NAME */ 1071 /* write the export name request */ 1072 if (nbd_send_option_request(ioc, NBD_OPT_EXPORT_NAME, -1, info->name, 1073 errp) < 0) { 1074 return -EINVAL; 1075 } 1076 1077 /* Read the response */ 1078 if (nbd_read64(ioc, &info->size, "export length", errp) < 0) { 1079 return -EINVAL; 1080 } 1081 1082 if (nbd_read16(ioc, &info->flags, "export flags", errp) < 0) { 1083 return -EINVAL; 1084 } 1085 break; 1086 case 0: /* oldstyle, parse length and flags */ 1087 if (*info->name) { 1088 error_setg(errp, "Server does not support non-empty export names"); 1089 return -EINVAL; 1090 } 1091 if (nbd_negotiate_finish_oldstyle(ioc, info, errp) < 0) { 1092 return -EINVAL; 1093 } 1094 break; 1095 default: 1096 return result; 1097 } 1098 1099 trace_nbd_receive_negotiate_size_flags(info->size, info->flags); 1100 if (zeroes && nbd_drop(ioc, 124, errp) < 0) { 1101 error_prepend(errp, "Failed to read reserved block: "); 1102 return -EINVAL; 1103 } 1104 return 0; 1105 } 1106 1107 /* Clean up result of nbd_receive_export_list */ 1108 void nbd_free_export_list(NBDExportInfo *info, int count) 1109 { 1110 int i, j; 1111 1112 if (!info) { 1113 return; 1114 } 1115 1116 for (i = 0; i < count; i++) { 1117 g_free(info[i].name); 1118 g_free(info[i].description); 1119 for (j = 0; j < info[i].n_contexts; j++) { 1120 g_free(info[i].contexts[j]); 1121 } 1122 g_free(info[i].contexts); 1123 } 1124 g_free(info); 1125 } 1126 1127 /* 1128 * nbd_receive_export_list: 1129 * Query details about a server's exports, then disconnect without 1130 * going into transmission phase. Return a count of the exports listed 1131 * in @info by the server, or -1 on error. Caller must free @info using 1132 * nbd_free_export_list(). 1133 */ 1134 int nbd_receive_export_list(QIOChannel *ioc, QCryptoTLSCreds *tlscreds, 1135 const char *hostname, NBDExportInfo **info, 1136 Error **errp) 1137 { 1138 int result; 1139 int count = 0; 1140 int i; 1141 int rc; 1142 int ret = -1; 1143 NBDExportInfo *array = NULL; 1144 QIOChannel *sioc = NULL; 1145 1146 *info = NULL; 1147 result = nbd_start_negotiate(NULL, ioc, tlscreds, hostname, &sioc, true, 1148 NULL, errp); 1149 if (tlscreds && sioc) { 1150 ioc = sioc; 1151 } 1152 1153 switch (result) { 1154 case 2: 1155 case 3: 1156 /* newstyle - use NBD_OPT_LIST to populate array, then try 1157 * NBD_OPT_INFO on each array member. If structured replies 1158 * are enabled, also try NBD_OPT_LIST_META_CONTEXT. */ 1159 if (nbd_send_option_request(ioc, NBD_OPT_LIST, 0, NULL, errp) < 0) { 1160 goto out; 1161 } 1162 while (1) { 1163 char *name; 1164 char *desc; 1165 1166 rc = nbd_receive_list(ioc, &name, &desc, errp); 1167 if (rc < 0) { 1168 goto out; 1169 } else if (rc == 0) { 1170 break; 1171 } 1172 array = g_renew(NBDExportInfo, array, ++count); 1173 memset(&array[count - 1], 0, sizeof(*array)); 1174 array[count - 1].name = name; 1175 array[count - 1].description = desc; 1176 array[count - 1].structured_reply = result == 3; 1177 } 1178 1179 for (i = 0; i < count; i++) { 1180 array[i].request_sizes = true; 1181 rc = nbd_opt_info_or_go(ioc, NBD_OPT_INFO, &array[i], errp); 1182 if (rc < 0) { 1183 goto out; 1184 } else if (rc == 0) { 1185 /* 1186 * Pointless to try rest of loop. If OPT_INFO doesn't work, 1187 * it's unlikely that meta contexts work either 1188 */ 1189 break; 1190 } 1191 1192 if (result == 3 && 1193 nbd_list_meta_contexts(ioc, &array[i], errp) < 0) { 1194 goto out; 1195 } 1196 } 1197 1198 /* Send NBD_OPT_ABORT as a courtesy before hanging up */ 1199 nbd_send_opt_abort(ioc); 1200 break; 1201 case 1: /* newstyle, but limited to EXPORT_NAME */ 1202 error_setg(errp, "Server does not support export lists"); 1203 /* We can't even send NBD_OPT_ABORT, so merely hang up */ 1204 goto out; 1205 case 0: /* oldstyle, parse length and flags */ 1206 array = g_new0(NBDExportInfo, 1); 1207 array->name = g_strdup(""); 1208 count = 1; 1209 1210 if (nbd_negotiate_finish_oldstyle(ioc, array, errp) < 0) { 1211 goto out; 1212 } 1213 1214 /* Send NBD_CMD_DISC as a courtesy to the server, but ignore all 1215 * errors now that we have the information we wanted. */ 1216 if (nbd_drop(ioc, 124, NULL) == 0) { 1217 NBDRequest request = { .type = NBD_CMD_DISC }; 1218 1219 nbd_send_request(ioc, &request); 1220 } 1221 break; 1222 default: 1223 goto out; 1224 } 1225 1226 *info = array; 1227 array = NULL; 1228 ret = count; 1229 1230 out: 1231 qio_channel_shutdown(ioc, QIO_CHANNEL_SHUTDOWN_BOTH, NULL); 1232 qio_channel_close(ioc, NULL); 1233 object_unref(OBJECT(sioc)); 1234 nbd_free_export_list(array, count); 1235 return ret; 1236 } 1237 1238 #ifdef __linux__ 1239 int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info, 1240 Error **errp) 1241 { 1242 unsigned long sector_size = MAX(BDRV_SECTOR_SIZE, info->min_block); 1243 unsigned long sectors = info->size / sector_size; 1244 1245 /* FIXME: Once the kernel module is patched to honor block sizes, 1246 * and to advertise that fact to user space, we should update the 1247 * hand-off to the kernel to use any block sizes we learned. */ 1248 assert(!info->request_sizes); 1249 if (info->size / sector_size != sectors) { 1250 error_setg(errp, "Export size %" PRIu64 " too large for 32-bit kernel", 1251 info->size); 1252 return -E2BIG; 1253 } 1254 1255 trace_nbd_init_set_socket(); 1256 1257 if (ioctl(fd, NBD_SET_SOCK, (unsigned long) sioc->fd) < 0) { 1258 int serrno = errno; 1259 error_setg(errp, "Failed to set NBD socket"); 1260 return -serrno; 1261 } 1262 1263 trace_nbd_init_set_block_size(sector_size); 1264 1265 if (ioctl(fd, NBD_SET_BLKSIZE, sector_size) < 0) { 1266 int serrno = errno; 1267 error_setg(errp, "Failed setting NBD block size"); 1268 return -serrno; 1269 } 1270 1271 trace_nbd_init_set_size(sectors); 1272 if (info->size % sector_size) { 1273 trace_nbd_init_trailing_bytes(info->size % sector_size); 1274 } 1275 1276 if (ioctl(fd, NBD_SET_SIZE_BLOCKS, sectors) < 0) { 1277 int serrno = errno; 1278 error_setg(errp, "Failed setting size (in blocks)"); 1279 return -serrno; 1280 } 1281 1282 if (ioctl(fd, NBD_SET_FLAGS, (unsigned long) info->flags) < 0) { 1283 if (errno == ENOTTY) { 1284 int read_only = (info->flags & NBD_FLAG_READ_ONLY) != 0; 1285 trace_nbd_init_set_readonly(); 1286 1287 if (ioctl(fd, BLKROSET, (unsigned long) &read_only) < 0) { 1288 int serrno = errno; 1289 error_setg(errp, "Failed setting read-only attribute"); 1290 return -serrno; 1291 } 1292 } else { 1293 int serrno = errno; 1294 error_setg(errp, "Failed setting flags"); 1295 return -serrno; 1296 } 1297 } 1298 1299 trace_nbd_init_finish(); 1300 1301 return 0; 1302 } 1303 1304 int nbd_client(int fd) 1305 { 1306 int ret; 1307 int serrno; 1308 1309 trace_nbd_client_loop(); 1310 1311 ret = ioctl(fd, NBD_DO_IT); 1312 if (ret < 0 && errno == EPIPE) { 1313 /* NBD_DO_IT normally returns EPIPE when someone has disconnected 1314 * the socket via NBD_DISCONNECT. We do not want to return 1 in 1315 * that case. 1316 */ 1317 ret = 0; 1318 } 1319 serrno = errno; 1320 1321 trace_nbd_client_loop_ret(ret, strerror(serrno)); 1322 1323 trace_nbd_client_clear_queue(); 1324 ioctl(fd, NBD_CLEAR_QUE); 1325 1326 trace_nbd_client_clear_socket(); 1327 ioctl(fd, NBD_CLEAR_SOCK); 1328 1329 errno = serrno; 1330 return ret; 1331 } 1332 1333 int nbd_disconnect(int fd) 1334 { 1335 ioctl(fd, NBD_CLEAR_QUE); 1336 ioctl(fd, NBD_DISCONNECT); 1337 ioctl(fd, NBD_CLEAR_SOCK); 1338 return 0; 1339 } 1340 1341 #endif /* __linux__ */ 1342 1343 int nbd_send_request(QIOChannel *ioc, NBDRequest *request) 1344 { 1345 uint8_t buf[NBD_REQUEST_SIZE]; 1346 1347 trace_nbd_send_request(request->from, request->len, request->handle, 1348 request->flags, request->type, 1349 nbd_cmd_lookup(request->type)); 1350 1351 stl_be_p(buf, NBD_REQUEST_MAGIC); 1352 stw_be_p(buf + 4, request->flags); 1353 stw_be_p(buf + 6, request->type); 1354 stq_be_p(buf + 8, request->handle); 1355 stq_be_p(buf + 16, request->from); 1356 stl_be_p(buf + 24, request->len); 1357 1358 return nbd_write(ioc, buf, sizeof(buf), NULL); 1359 } 1360 1361 /* nbd_receive_simple_reply 1362 * Read simple reply except magic field (which should be already read). 1363 * Payload is not read (payload is possible for CMD_READ, but here we even 1364 * don't know whether it take place or not). 1365 */ 1366 static int nbd_receive_simple_reply(QIOChannel *ioc, NBDSimpleReply *reply, 1367 Error **errp) 1368 { 1369 int ret; 1370 1371 assert(reply->magic == NBD_SIMPLE_REPLY_MAGIC); 1372 1373 ret = nbd_read(ioc, (uint8_t *)reply + sizeof(reply->magic), 1374 sizeof(*reply) - sizeof(reply->magic), "reply", errp); 1375 if (ret < 0) { 1376 return ret; 1377 } 1378 1379 reply->error = be32_to_cpu(reply->error); 1380 reply->handle = be64_to_cpu(reply->handle); 1381 1382 return 0; 1383 } 1384 1385 /* nbd_receive_structured_reply_chunk 1386 * Read structured reply chunk except magic field (which should be already 1387 * read). 1388 * Payload is not read. 1389 */ 1390 static int nbd_receive_structured_reply_chunk(QIOChannel *ioc, 1391 NBDStructuredReplyChunk *chunk, 1392 Error **errp) 1393 { 1394 int ret; 1395 1396 assert(chunk->magic == NBD_STRUCTURED_REPLY_MAGIC); 1397 1398 ret = nbd_read(ioc, (uint8_t *)chunk + sizeof(chunk->magic), 1399 sizeof(*chunk) - sizeof(chunk->magic), "structured chunk", 1400 errp); 1401 if (ret < 0) { 1402 return ret; 1403 } 1404 1405 chunk->flags = be16_to_cpu(chunk->flags); 1406 chunk->type = be16_to_cpu(chunk->type); 1407 chunk->handle = be64_to_cpu(chunk->handle); 1408 chunk->length = be32_to_cpu(chunk->length); 1409 1410 return 0; 1411 } 1412 1413 /* nbd_read_eof 1414 * Tries to read @size bytes from @ioc. 1415 * Returns 1 on success 1416 * 0 on eof, when no data was read (errp is not set) 1417 * negative errno on failure (errp is set) 1418 */ 1419 static inline int coroutine_fn 1420 nbd_read_eof(BlockDriverState *bs, QIOChannel *ioc, void *buffer, size_t size, 1421 Error **errp) 1422 { 1423 bool partial = false; 1424 1425 assert(size); 1426 while (size > 0) { 1427 struct iovec iov = { .iov_base = buffer, .iov_len = size }; 1428 ssize_t len; 1429 1430 len = qio_channel_readv(ioc, &iov, 1, errp); 1431 if (len == QIO_CHANNEL_ERR_BLOCK) { 1432 bdrv_dec_in_flight(bs); 1433 qio_channel_yield(ioc, G_IO_IN); 1434 bdrv_inc_in_flight(bs); 1435 continue; 1436 } else if (len < 0) { 1437 return -EIO; 1438 } else if (len == 0) { 1439 if (partial) { 1440 error_setg(errp, 1441 "Unexpected end-of-file before all bytes were read"); 1442 return -EIO; 1443 } else { 1444 return 0; 1445 } 1446 } 1447 1448 partial = true; 1449 size -= len; 1450 buffer = (uint8_t*) buffer + len; 1451 } 1452 return 1; 1453 } 1454 1455 /* nbd_receive_reply 1456 * 1457 * Decreases bs->in_flight while waiting for a new reply. This yield is where 1458 * we wait indefinitely and the coroutine must be able to be safely reentered 1459 * for nbd_client_attach_aio_context(). 1460 * 1461 * Returns 1 on success 1462 * 0 on eof, when no data was read (errp is not set) 1463 * negative errno on failure (errp is set) 1464 */ 1465 int coroutine_fn nbd_receive_reply(BlockDriverState *bs, QIOChannel *ioc, 1466 NBDReply *reply, Error **errp) 1467 { 1468 int ret; 1469 const char *type; 1470 1471 ret = nbd_read_eof(bs, ioc, &reply->magic, sizeof(reply->magic), errp); 1472 if (ret <= 0) { 1473 return ret; 1474 } 1475 1476 reply->magic = be32_to_cpu(reply->magic); 1477 1478 switch (reply->magic) { 1479 case NBD_SIMPLE_REPLY_MAGIC: 1480 ret = nbd_receive_simple_reply(ioc, &reply->simple, errp); 1481 if (ret < 0) { 1482 break; 1483 } 1484 trace_nbd_receive_simple_reply(reply->simple.error, 1485 nbd_err_lookup(reply->simple.error), 1486 reply->handle); 1487 break; 1488 case NBD_STRUCTURED_REPLY_MAGIC: 1489 ret = nbd_receive_structured_reply_chunk(ioc, &reply->structured, errp); 1490 if (ret < 0) { 1491 break; 1492 } 1493 type = nbd_reply_type_lookup(reply->structured.type); 1494 trace_nbd_receive_structured_reply_chunk(reply->structured.flags, 1495 reply->structured.type, type, 1496 reply->structured.handle, 1497 reply->structured.length); 1498 break; 1499 default: 1500 error_setg(errp, "invalid magic (got 0x%" PRIx32 ")", reply->magic); 1501 return -EINVAL; 1502 } 1503 if (ret < 0) { 1504 return ret; 1505 } 1506 1507 return 1; 1508 } 1509 1510