1 /* 2 * Secure Shell (ssh) backend for QEMU. 3 * 4 * Copyright (C) 2013 Red Hat Inc., Richard W.M. Jones <rjones@redhat.com> 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a copy 7 * of this software and associated documentation files (the "Software"), to deal 8 * in the Software without restriction, including without limitation the rights 9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 10 * copies of the Software, and to permit persons to whom the Software is 11 * furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 22 * THE SOFTWARE. 23 */ 24 25 #include "qemu/osdep.h" 26 27 #include <libssh/libssh.h> 28 #include <libssh/sftp.h> 29 30 #include "block/block_int.h" 31 #include "block/qdict.h" 32 #include "qapi/error.h" 33 #include "qemu/error-report.h" 34 #include "qemu/module.h" 35 #include "qemu/option.h" 36 #include "qemu/ctype.h" 37 #include "qemu/cutils.h" 38 #include "qemu/sockets.h" 39 #include "qemu/uri.h" 40 #include "qapi/qapi-visit-sockets.h" 41 #include "qapi/qapi-visit-block-core.h" 42 #include "qapi/qmp/qdict.h" 43 #include "qapi/qmp/qstring.h" 44 #include "qapi/qobject-input-visitor.h" 45 #include "qapi/qobject-output-visitor.h" 46 #include "trace.h" 47 48 /* 49 * TRACE_LIBSSH=<level> enables tracing in libssh itself. 50 * The meaning of <level> is described here: 51 * http://api.libssh.org/master/group__libssh__log.html 52 */ 53 #define TRACE_LIBSSH 0 /* see: SSH_LOG_* */ 54 55 typedef struct BDRVSSHState { 56 /* Coroutine. */ 57 CoMutex lock; 58 59 /* SSH connection. */ 60 int sock; /* socket */ 61 ssh_session session; /* ssh session */ 62 sftp_session sftp; /* sftp session */ 63 sftp_file sftp_handle; /* sftp remote file handle */ 64 65 /* 66 * File attributes at open. We try to keep the .size field 67 * updated if it changes (eg by writing at the end of the file). 68 */ 69 sftp_attributes attrs; 70 71 InetSocketAddress *inet; 72 73 /* Used to warn if 'flush' is not supported. */ 74 bool unsafe_flush_warning; 75 76 /* 77 * Store the user name for ssh_refresh_filename() because the 78 * default depends on the system you are on -- therefore, when we 79 * generate a filename, it should always contain the user name we 80 * are actually using. 81 */ 82 char *user; 83 } BDRVSSHState; 84 85 static void ssh_state_init(BDRVSSHState *s) 86 { 87 memset(s, 0, sizeof *s); 88 s->sock = -1; 89 qemu_co_mutex_init(&s->lock); 90 } 91 92 static void ssh_state_free(BDRVSSHState *s) 93 { 94 g_free(s->user); 95 96 if (s->attrs) { 97 sftp_attributes_free(s->attrs); 98 } 99 if (s->sftp_handle) { 100 sftp_close(s->sftp_handle); 101 } 102 if (s->sftp) { 103 sftp_free(s->sftp); 104 } 105 if (s->session) { 106 ssh_disconnect(s->session); 107 ssh_free(s->session); /* This frees s->sock */ 108 } 109 } 110 111 static void GCC_FMT_ATTR(3, 4) 112 session_error_setg(Error **errp, BDRVSSHState *s, const char *fs, ...) 113 { 114 va_list args; 115 char *msg; 116 117 va_start(args, fs); 118 msg = g_strdup_vprintf(fs, args); 119 va_end(args); 120 121 if (s->session) { 122 const char *ssh_err; 123 int ssh_err_code; 124 125 /* This is not an errno. See <libssh/libssh.h>. */ 126 ssh_err = ssh_get_error(s->session); 127 ssh_err_code = ssh_get_error_code(s->session); 128 error_setg(errp, "%s: %s (libssh error code: %d)", 129 msg, ssh_err, ssh_err_code); 130 } else { 131 error_setg(errp, "%s", msg); 132 } 133 g_free(msg); 134 } 135 136 static void GCC_FMT_ATTR(3, 4) 137 sftp_error_setg(Error **errp, BDRVSSHState *s, const char *fs, ...) 138 { 139 va_list args; 140 char *msg; 141 142 va_start(args, fs); 143 msg = g_strdup_vprintf(fs, args); 144 va_end(args); 145 146 if (s->sftp) { 147 const char *ssh_err; 148 int ssh_err_code; 149 int sftp_err_code; 150 151 /* This is not an errno. See <libssh/libssh.h>. */ 152 ssh_err = ssh_get_error(s->session); 153 ssh_err_code = ssh_get_error_code(s->session); 154 /* See <libssh/sftp.h>. */ 155 sftp_err_code = sftp_get_error(s->sftp); 156 157 error_setg(errp, 158 "%s: %s (libssh error code: %d, sftp error code: %d)", 159 msg, ssh_err, ssh_err_code, sftp_err_code); 160 } else { 161 error_setg(errp, "%s", msg); 162 } 163 g_free(msg); 164 } 165 166 static void sftp_error_trace(BDRVSSHState *s, const char *op) 167 { 168 const char *ssh_err; 169 int ssh_err_code; 170 int sftp_err_code; 171 172 /* This is not an errno. See <libssh/libssh.h>. */ 173 ssh_err = ssh_get_error(s->session); 174 ssh_err_code = ssh_get_error_code(s->session); 175 /* See <libssh/sftp.h>. */ 176 sftp_err_code = sftp_get_error(s->sftp); 177 178 trace_sftp_error(op, ssh_err, ssh_err_code, sftp_err_code); 179 } 180 181 static int parse_uri(const char *filename, QDict *options, Error **errp) 182 { 183 URI *uri = NULL; 184 QueryParams *qp; 185 char *port_str; 186 int i; 187 188 uri = uri_parse(filename); 189 if (!uri) { 190 return -EINVAL; 191 } 192 193 if (g_strcmp0(uri->scheme, "ssh") != 0) { 194 error_setg(errp, "URI scheme must be 'ssh'"); 195 goto err; 196 } 197 198 if (!uri->server || strcmp(uri->server, "") == 0) { 199 error_setg(errp, "missing hostname in URI"); 200 goto err; 201 } 202 203 if (!uri->path || strcmp(uri->path, "") == 0) { 204 error_setg(errp, "missing remote path in URI"); 205 goto err; 206 } 207 208 qp = query_params_parse(uri->query); 209 if (!qp) { 210 error_setg(errp, "could not parse query parameters"); 211 goto err; 212 } 213 214 if(uri->user && strcmp(uri->user, "") != 0) { 215 qdict_put_str(options, "user", uri->user); 216 } 217 218 qdict_put_str(options, "server.host", uri->server); 219 220 port_str = g_strdup_printf("%d", uri->port ?: 22); 221 qdict_put_str(options, "server.port", port_str); 222 g_free(port_str); 223 224 qdict_put_str(options, "path", uri->path); 225 226 /* Pick out any query parameters that we understand, and ignore 227 * the rest. 228 */ 229 for (i = 0; i < qp->n; ++i) { 230 if (strcmp(qp->p[i].name, "host_key_check") == 0) { 231 qdict_put_str(options, "host_key_check", qp->p[i].value); 232 } 233 } 234 235 query_params_free(qp); 236 uri_free(uri); 237 return 0; 238 239 err: 240 if (uri) { 241 uri_free(uri); 242 } 243 return -EINVAL; 244 } 245 246 static bool ssh_has_filename_options_conflict(QDict *options, Error **errp) 247 { 248 const QDictEntry *qe; 249 250 for (qe = qdict_first(options); qe; qe = qdict_next(options, qe)) { 251 if (!strcmp(qe->key, "host") || 252 !strcmp(qe->key, "port") || 253 !strcmp(qe->key, "path") || 254 !strcmp(qe->key, "user") || 255 !strcmp(qe->key, "host_key_check") || 256 strstart(qe->key, "server.", NULL)) 257 { 258 error_setg(errp, "Option '%s' cannot be used with a file name", 259 qe->key); 260 return true; 261 } 262 } 263 264 return false; 265 } 266 267 static void ssh_parse_filename(const char *filename, QDict *options, 268 Error **errp) 269 { 270 if (ssh_has_filename_options_conflict(options, errp)) { 271 return; 272 } 273 274 parse_uri(filename, options, errp); 275 } 276 277 static int check_host_key_knownhosts(BDRVSSHState *s, Error **errp) 278 { 279 int ret; 280 enum ssh_known_hosts_e state; 281 int r; 282 ssh_key pubkey; 283 enum ssh_keytypes_e pubkey_type; 284 unsigned char *server_hash = NULL; 285 size_t server_hash_len; 286 char *fingerprint = NULL; 287 288 state = ssh_session_is_known_server(s->session); 289 trace_ssh_server_status(state); 290 291 switch (state) { 292 case SSH_KNOWN_HOSTS_OK: 293 /* OK */ 294 trace_ssh_check_host_key_knownhosts(); 295 break; 296 case SSH_KNOWN_HOSTS_CHANGED: 297 ret = -EINVAL; 298 r = ssh_get_server_publickey(s->session, &pubkey); 299 if (r == 0) { 300 r = ssh_get_publickey_hash(pubkey, SSH_PUBLICKEY_HASH_SHA256, 301 &server_hash, &server_hash_len); 302 pubkey_type = ssh_key_type(pubkey); 303 ssh_key_free(pubkey); 304 } 305 if (r == 0) { 306 fingerprint = ssh_get_fingerprint_hash(SSH_PUBLICKEY_HASH_SHA256, 307 server_hash, 308 server_hash_len); 309 ssh_clean_pubkey_hash(&server_hash); 310 } 311 if (fingerprint) { 312 error_setg(errp, 313 "host key (%s key with fingerprint %s) does not match " 314 "the one in known_hosts; this may be a possible attack", 315 ssh_key_type_to_char(pubkey_type), fingerprint); 316 ssh_string_free_char(fingerprint); 317 } else { 318 error_setg(errp, 319 "host key does not match the one in known_hosts; this " 320 "may be a possible attack"); 321 } 322 goto out; 323 case SSH_KNOWN_HOSTS_OTHER: 324 ret = -EINVAL; 325 error_setg(errp, 326 "host key for this server not found, another type exists"); 327 goto out; 328 case SSH_KNOWN_HOSTS_UNKNOWN: 329 ret = -EINVAL; 330 error_setg(errp, "no host key was found in known_hosts"); 331 goto out; 332 case SSH_KNOWN_HOSTS_NOT_FOUND: 333 ret = -ENOENT; 334 error_setg(errp, "known_hosts file not found"); 335 goto out; 336 case SSH_KNOWN_HOSTS_ERROR: 337 ret = -EINVAL; 338 error_setg(errp, "error while checking the host"); 339 goto out; 340 default: 341 ret = -EINVAL; 342 error_setg(errp, "error while checking for known server (%d)", state); 343 goto out; 344 } 345 346 /* known_hosts checking successful. */ 347 ret = 0; 348 349 out: 350 return ret; 351 } 352 353 static unsigned hex2decimal(char ch) 354 { 355 if (ch >= '0' && ch <= '9') { 356 return (ch - '0'); 357 } else if (ch >= 'a' && ch <= 'f') { 358 return 10 + (ch - 'a'); 359 } else if (ch >= 'A' && ch <= 'F') { 360 return 10 + (ch - 'A'); 361 } 362 363 return -1; 364 } 365 366 /* Compare the binary fingerprint (hash of host key) with the 367 * host_key_check parameter. 368 */ 369 static int compare_fingerprint(const unsigned char *fingerprint, size_t len, 370 const char *host_key_check) 371 { 372 unsigned c; 373 374 while (len > 0) { 375 while (*host_key_check == ':') 376 host_key_check++; 377 if (!qemu_isxdigit(host_key_check[0]) || 378 !qemu_isxdigit(host_key_check[1])) 379 return 1; 380 c = hex2decimal(host_key_check[0]) * 16 + 381 hex2decimal(host_key_check[1]); 382 if (c - *fingerprint != 0) 383 return c - *fingerprint; 384 fingerprint++; 385 len--; 386 host_key_check += 2; 387 } 388 return *host_key_check - '\0'; 389 } 390 391 static int 392 check_host_key_hash(BDRVSSHState *s, const char *hash, 393 enum ssh_publickey_hash_type type, Error **errp) 394 { 395 int r; 396 ssh_key pubkey; 397 unsigned char *server_hash; 398 size_t server_hash_len; 399 400 r = ssh_get_server_publickey(s->session, &pubkey); 401 if (r != SSH_OK) { 402 session_error_setg(errp, s, "failed to read remote host key"); 403 return -EINVAL; 404 } 405 406 r = ssh_get_publickey_hash(pubkey, type, &server_hash, &server_hash_len); 407 ssh_key_free(pubkey); 408 if (r != 0) { 409 session_error_setg(errp, s, 410 "failed reading the hash of the server SSH key"); 411 return -EINVAL; 412 } 413 414 r = compare_fingerprint(server_hash, server_hash_len, hash); 415 ssh_clean_pubkey_hash(&server_hash); 416 if (r != 0) { 417 error_setg(errp, "remote host key does not match host_key_check '%s'", 418 hash); 419 return -EPERM; 420 } 421 422 return 0; 423 } 424 425 static int check_host_key(BDRVSSHState *s, SshHostKeyCheck *hkc, Error **errp) 426 { 427 SshHostKeyCheckMode mode; 428 429 if (hkc) { 430 mode = hkc->mode; 431 } else { 432 mode = SSH_HOST_KEY_CHECK_MODE_KNOWN_HOSTS; 433 } 434 435 switch (mode) { 436 case SSH_HOST_KEY_CHECK_MODE_NONE: 437 return 0; 438 case SSH_HOST_KEY_CHECK_MODE_HASH: 439 if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_MD5) { 440 return check_host_key_hash(s, hkc->u.hash.hash, 441 SSH_PUBLICKEY_HASH_MD5, errp); 442 } else if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_SHA1) { 443 return check_host_key_hash(s, hkc->u.hash.hash, 444 SSH_PUBLICKEY_HASH_SHA1, errp); 445 } else if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_SHA256) { 446 return check_host_key_hash(s, hkc->u.hash.hash, 447 SSH_PUBLICKEY_HASH_SHA256, errp); 448 } 449 g_assert_not_reached(); 450 break; 451 case SSH_HOST_KEY_CHECK_MODE_KNOWN_HOSTS: 452 return check_host_key_knownhosts(s, errp); 453 default: 454 g_assert_not_reached(); 455 } 456 457 return -EINVAL; 458 } 459 460 static int authenticate(BDRVSSHState *s, Error **errp) 461 { 462 int r, ret; 463 int method; 464 465 /* Try to authenticate with the "none" method. */ 466 r = ssh_userauth_none(s->session, NULL); 467 if (r == SSH_AUTH_ERROR) { 468 ret = -EPERM; 469 session_error_setg(errp, s, "failed to authenticate using none " 470 "authentication"); 471 goto out; 472 } else if (r == SSH_AUTH_SUCCESS) { 473 /* Authenticated! */ 474 ret = 0; 475 goto out; 476 } 477 478 method = ssh_userauth_list(s->session, NULL); 479 trace_ssh_auth_methods(method); 480 481 /* 482 * Try to authenticate with publickey, using the ssh-agent 483 * if available. 484 */ 485 if (method & SSH_AUTH_METHOD_PUBLICKEY) { 486 r = ssh_userauth_publickey_auto(s->session, NULL, NULL); 487 if (r == SSH_AUTH_ERROR) { 488 ret = -EINVAL; 489 session_error_setg(errp, s, "failed to authenticate using " 490 "publickey authentication"); 491 goto out; 492 } else if (r == SSH_AUTH_SUCCESS) { 493 /* Authenticated! */ 494 ret = 0; 495 goto out; 496 } 497 } 498 499 ret = -EPERM; 500 error_setg(errp, "failed to authenticate using publickey authentication " 501 "and the identities held by your ssh-agent"); 502 503 out: 504 return ret; 505 } 506 507 static QemuOptsList ssh_runtime_opts = { 508 .name = "ssh", 509 .head = QTAILQ_HEAD_INITIALIZER(ssh_runtime_opts.head), 510 .desc = { 511 { 512 .name = "host", 513 .type = QEMU_OPT_STRING, 514 .help = "Host to connect to", 515 }, 516 { 517 .name = "port", 518 .type = QEMU_OPT_NUMBER, 519 .help = "Port to connect to", 520 }, 521 { 522 .name = "host_key_check", 523 .type = QEMU_OPT_STRING, 524 .help = "Defines how and what to check the host key against", 525 }, 526 { /* end of list */ } 527 }, 528 }; 529 530 static bool ssh_process_legacy_options(QDict *output_opts, 531 QemuOpts *legacy_opts, 532 Error **errp) 533 { 534 const char *host = qemu_opt_get(legacy_opts, "host"); 535 const char *port = qemu_opt_get(legacy_opts, "port"); 536 const char *host_key_check = qemu_opt_get(legacy_opts, "host_key_check"); 537 538 if (!host && port) { 539 error_setg(errp, "port may not be used without host"); 540 return false; 541 } 542 543 if (host) { 544 qdict_put_str(output_opts, "server.host", host); 545 qdict_put_str(output_opts, "server.port", port ?: stringify(22)); 546 } 547 548 if (host_key_check) { 549 if (strcmp(host_key_check, "no") == 0) { 550 qdict_put_str(output_opts, "host-key-check.mode", "none"); 551 } else if (strncmp(host_key_check, "md5:", 4) == 0) { 552 qdict_put_str(output_opts, "host-key-check.mode", "hash"); 553 qdict_put_str(output_opts, "host-key-check.type", "md5"); 554 qdict_put_str(output_opts, "host-key-check.hash", 555 &host_key_check[4]); 556 } else if (strncmp(host_key_check, "sha1:", 5) == 0) { 557 qdict_put_str(output_opts, "host-key-check.mode", "hash"); 558 qdict_put_str(output_opts, "host-key-check.type", "sha1"); 559 qdict_put_str(output_opts, "host-key-check.hash", 560 &host_key_check[5]); 561 } else if (strcmp(host_key_check, "yes") == 0) { 562 qdict_put_str(output_opts, "host-key-check.mode", "known_hosts"); 563 } else { 564 error_setg(errp, "unknown host_key_check setting (%s)", 565 host_key_check); 566 return false; 567 } 568 } 569 570 return true; 571 } 572 573 static BlockdevOptionsSsh *ssh_parse_options(QDict *options, Error **errp) 574 { 575 BlockdevOptionsSsh *result = NULL; 576 QemuOpts *opts = NULL; 577 const QDictEntry *e; 578 Visitor *v; 579 580 /* Translate legacy options */ 581 opts = qemu_opts_create(&ssh_runtime_opts, NULL, 0, &error_abort); 582 if (!qemu_opts_absorb_qdict(opts, options, errp)) { 583 goto fail; 584 } 585 586 if (!ssh_process_legacy_options(options, opts, errp)) { 587 goto fail; 588 } 589 590 /* Create the QAPI object */ 591 v = qobject_input_visitor_new_flat_confused(options, errp); 592 if (!v) { 593 goto fail; 594 } 595 596 visit_type_BlockdevOptionsSsh(v, NULL, &result, errp); 597 visit_free(v); 598 if (!result) { 599 goto fail; 600 } 601 602 /* Remove the processed options from the QDict (the visitor processes 603 * _all_ options in the QDict) */ 604 while ((e = qdict_first(options))) { 605 qdict_del(options, e->key); 606 } 607 608 fail: 609 qemu_opts_del(opts); 610 return result; 611 } 612 613 static int connect_to_ssh(BDRVSSHState *s, BlockdevOptionsSsh *opts, 614 int ssh_flags, int creat_mode, Error **errp) 615 { 616 int r, ret; 617 unsigned int port = 0; 618 int new_sock = -1; 619 620 if (opts->has_user) { 621 s->user = g_strdup(opts->user); 622 } else { 623 s->user = g_strdup(g_get_user_name()); 624 if (!s->user) { 625 error_setg_errno(errp, errno, "Can't get user name"); 626 ret = -errno; 627 goto err; 628 } 629 } 630 631 /* Pop the config into our state object, Exit if invalid */ 632 s->inet = opts->server; 633 opts->server = NULL; 634 635 if (qemu_strtoui(s->inet->port, NULL, 10, &port) < 0) { 636 error_setg(errp, "Use only numeric port value"); 637 ret = -EINVAL; 638 goto err; 639 } 640 641 /* Open the socket and connect. */ 642 new_sock = inet_connect_saddr(s->inet, errp); 643 if (new_sock < 0) { 644 ret = -EIO; 645 goto err; 646 } 647 648 /* 649 * Try to disable the Nagle algorithm on TCP sockets to reduce latency, 650 * but do not fail if it cannot be disabled. 651 */ 652 r = socket_set_nodelay(new_sock); 653 if (r < 0) { 654 warn_report("can't set TCP_NODELAY for the ssh server %s: %s", 655 s->inet->host, strerror(errno)); 656 } 657 658 /* Create SSH session. */ 659 s->session = ssh_new(); 660 if (!s->session) { 661 ret = -EINVAL; 662 session_error_setg(errp, s, "failed to initialize libssh session"); 663 goto err; 664 } 665 666 /* 667 * Make sure we are in blocking mode during the connection and 668 * authentication phases. 669 */ 670 ssh_set_blocking(s->session, 1); 671 672 r = ssh_options_set(s->session, SSH_OPTIONS_USER, s->user); 673 if (r < 0) { 674 ret = -EINVAL; 675 session_error_setg(errp, s, 676 "failed to set the user in the libssh session"); 677 goto err; 678 } 679 680 r = ssh_options_set(s->session, SSH_OPTIONS_HOST, s->inet->host); 681 if (r < 0) { 682 ret = -EINVAL; 683 session_error_setg(errp, s, 684 "failed to set the host in the libssh session"); 685 goto err; 686 } 687 688 if (port > 0) { 689 r = ssh_options_set(s->session, SSH_OPTIONS_PORT, &port); 690 if (r < 0) { 691 ret = -EINVAL; 692 session_error_setg(errp, s, 693 "failed to set the port in the libssh session"); 694 goto err; 695 } 696 } 697 698 r = ssh_options_set(s->session, SSH_OPTIONS_COMPRESSION, "none"); 699 if (r < 0) { 700 ret = -EINVAL; 701 session_error_setg(errp, s, 702 "failed to disable the compression in the libssh " 703 "session"); 704 goto err; 705 } 706 707 /* Read ~/.ssh/config. */ 708 r = ssh_options_parse_config(s->session, NULL); 709 if (r < 0) { 710 ret = -EINVAL; 711 session_error_setg(errp, s, "failed to parse ~/.ssh/config"); 712 goto err; 713 } 714 715 r = ssh_options_set(s->session, SSH_OPTIONS_FD, &new_sock); 716 if (r < 0) { 717 ret = -EINVAL; 718 session_error_setg(errp, s, 719 "failed to set the socket in the libssh session"); 720 goto err; 721 } 722 /* libssh took ownership of the socket. */ 723 s->sock = new_sock; 724 new_sock = -1; 725 726 /* Connect. */ 727 r = ssh_connect(s->session); 728 if (r != SSH_OK) { 729 ret = -EINVAL; 730 session_error_setg(errp, s, "failed to establish SSH session"); 731 goto err; 732 } 733 734 /* Check the remote host's key against known_hosts. */ 735 ret = check_host_key(s, opts->host_key_check, errp); 736 if (ret < 0) { 737 goto err; 738 } 739 740 /* Authenticate. */ 741 ret = authenticate(s, errp); 742 if (ret < 0) { 743 goto err; 744 } 745 746 /* Start SFTP. */ 747 s->sftp = sftp_new(s->session); 748 if (!s->sftp) { 749 session_error_setg(errp, s, "failed to create sftp handle"); 750 ret = -EINVAL; 751 goto err; 752 } 753 754 r = sftp_init(s->sftp); 755 if (r < 0) { 756 sftp_error_setg(errp, s, "failed to initialize sftp handle"); 757 ret = -EINVAL; 758 goto err; 759 } 760 761 /* Open the remote file. */ 762 trace_ssh_connect_to_ssh(opts->path, ssh_flags, creat_mode); 763 s->sftp_handle = sftp_open(s->sftp, opts->path, ssh_flags, creat_mode); 764 if (!s->sftp_handle) { 765 sftp_error_setg(errp, s, "failed to open remote file '%s'", 766 opts->path); 767 ret = -EINVAL; 768 goto err; 769 } 770 771 /* Make sure the SFTP file is handled in blocking mode. */ 772 sftp_file_set_blocking(s->sftp_handle); 773 774 s->attrs = sftp_fstat(s->sftp_handle); 775 if (!s->attrs) { 776 sftp_error_setg(errp, s, "failed to read file attributes"); 777 return -EINVAL; 778 } 779 780 return 0; 781 782 err: 783 if (s->attrs) { 784 sftp_attributes_free(s->attrs); 785 } 786 s->attrs = NULL; 787 if (s->sftp_handle) { 788 sftp_close(s->sftp_handle); 789 } 790 s->sftp_handle = NULL; 791 if (s->sftp) { 792 sftp_free(s->sftp); 793 } 794 s->sftp = NULL; 795 if (s->session) { 796 ssh_disconnect(s->session); 797 ssh_free(s->session); 798 } 799 s->session = NULL; 800 s->sock = -1; 801 if (new_sock >= 0) { 802 close(new_sock); 803 } 804 805 return ret; 806 } 807 808 static int ssh_file_open(BlockDriverState *bs, QDict *options, int bdrv_flags, 809 Error **errp) 810 { 811 BDRVSSHState *s = bs->opaque; 812 BlockdevOptionsSsh *opts; 813 int ret; 814 int ssh_flags; 815 816 ssh_state_init(s); 817 818 ssh_flags = 0; 819 if (bdrv_flags & BDRV_O_RDWR) { 820 ssh_flags |= O_RDWR; 821 } else { 822 ssh_flags |= O_RDONLY; 823 } 824 825 opts = ssh_parse_options(options, errp); 826 if (opts == NULL) { 827 return -EINVAL; 828 } 829 830 /* Start up SSH. */ 831 ret = connect_to_ssh(s, opts, ssh_flags, 0, errp); 832 if (ret < 0) { 833 goto err; 834 } 835 836 /* Go non-blocking. */ 837 ssh_set_blocking(s->session, 0); 838 839 if (s->attrs->type == SSH_FILEXFER_TYPE_REGULAR) { 840 bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE; 841 } 842 843 qapi_free_BlockdevOptionsSsh(opts); 844 845 return 0; 846 847 err: 848 qapi_free_BlockdevOptionsSsh(opts); 849 850 return ret; 851 } 852 853 /* Note: This is a blocking operation */ 854 static int ssh_grow_file(BDRVSSHState *s, int64_t offset, Error **errp) 855 { 856 ssize_t ret; 857 char c[1] = { '\0' }; 858 int was_blocking = ssh_is_blocking(s->session); 859 860 /* offset must be strictly greater than the current size so we do 861 * not overwrite anything */ 862 assert(offset > 0 && offset > s->attrs->size); 863 864 ssh_set_blocking(s->session, 1); 865 866 sftp_seek64(s->sftp_handle, offset - 1); 867 ret = sftp_write(s->sftp_handle, c, 1); 868 869 ssh_set_blocking(s->session, was_blocking); 870 871 if (ret < 0) { 872 sftp_error_setg(errp, s, "Failed to grow file"); 873 return -EIO; 874 } 875 876 s->attrs->size = offset; 877 return 0; 878 } 879 880 static QemuOptsList ssh_create_opts = { 881 .name = "ssh-create-opts", 882 .head = QTAILQ_HEAD_INITIALIZER(ssh_create_opts.head), 883 .desc = { 884 { 885 .name = BLOCK_OPT_SIZE, 886 .type = QEMU_OPT_SIZE, 887 .help = "Virtual disk size" 888 }, 889 { /* end of list */ } 890 } 891 }; 892 893 static int ssh_co_create(BlockdevCreateOptions *options, Error **errp) 894 { 895 BlockdevCreateOptionsSsh *opts = &options->u.ssh; 896 BDRVSSHState s; 897 int ret; 898 899 assert(options->driver == BLOCKDEV_DRIVER_SSH); 900 901 ssh_state_init(&s); 902 903 ret = connect_to_ssh(&s, opts->location, 904 O_RDWR | O_CREAT | O_TRUNC, 905 0644, errp); 906 if (ret < 0) { 907 goto fail; 908 } 909 910 if (opts->size > 0) { 911 ret = ssh_grow_file(&s, opts->size, errp); 912 if (ret < 0) { 913 goto fail; 914 } 915 } 916 917 ret = 0; 918 fail: 919 ssh_state_free(&s); 920 return ret; 921 } 922 923 static int coroutine_fn ssh_co_create_opts(BlockDriver *drv, 924 const char *filename, 925 QemuOpts *opts, 926 Error **errp) 927 { 928 BlockdevCreateOptions *create_options; 929 BlockdevCreateOptionsSsh *ssh_opts; 930 int ret; 931 QDict *uri_options = NULL; 932 933 create_options = g_new0(BlockdevCreateOptions, 1); 934 create_options->driver = BLOCKDEV_DRIVER_SSH; 935 ssh_opts = &create_options->u.ssh; 936 937 /* Get desired file size. */ 938 ssh_opts->size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0), 939 BDRV_SECTOR_SIZE); 940 trace_ssh_co_create_opts(ssh_opts->size); 941 942 uri_options = qdict_new(); 943 ret = parse_uri(filename, uri_options, errp); 944 if (ret < 0) { 945 goto out; 946 } 947 948 ssh_opts->location = ssh_parse_options(uri_options, errp); 949 if (ssh_opts->location == NULL) { 950 ret = -EINVAL; 951 goto out; 952 } 953 954 ret = ssh_co_create(create_options, errp); 955 956 out: 957 qobject_unref(uri_options); 958 qapi_free_BlockdevCreateOptions(create_options); 959 return ret; 960 } 961 962 static void ssh_close(BlockDriverState *bs) 963 { 964 BDRVSSHState *s = bs->opaque; 965 966 ssh_state_free(s); 967 } 968 969 static int ssh_has_zero_init(BlockDriverState *bs) 970 { 971 BDRVSSHState *s = bs->opaque; 972 /* Assume false, unless we can positively prove it's true. */ 973 int has_zero_init = 0; 974 975 if (s->attrs->type == SSH_FILEXFER_TYPE_REGULAR) { 976 has_zero_init = 1; 977 } 978 979 return has_zero_init; 980 } 981 982 typedef struct BDRVSSHRestart { 983 BlockDriverState *bs; 984 Coroutine *co; 985 } BDRVSSHRestart; 986 987 static void restart_coroutine(void *opaque) 988 { 989 BDRVSSHRestart *restart = opaque; 990 BlockDriverState *bs = restart->bs; 991 BDRVSSHState *s = bs->opaque; 992 AioContext *ctx = bdrv_get_aio_context(bs); 993 994 trace_ssh_restart_coroutine(restart->co); 995 aio_set_fd_handler(ctx, s->sock, false, NULL, NULL, NULL, NULL); 996 997 aio_co_wake(restart->co); 998 } 999 1000 /* A non-blocking call returned EAGAIN, so yield, ensuring the 1001 * handlers are set up so that we'll be rescheduled when there is an 1002 * interesting event on the socket. 1003 */ 1004 static coroutine_fn void co_yield(BDRVSSHState *s, BlockDriverState *bs) 1005 { 1006 int r; 1007 IOHandler *rd_handler = NULL, *wr_handler = NULL; 1008 BDRVSSHRestart restart = { 1009 .bs = bs, 1010 .co = qemu_coroutine_self() 1011 }; 1012 1013 r = ssh_get_poll_flags(s->session); 1014 1015 if (r & SSH_READ_PENDING) { 1016 rd_handler = restart_coroutine; 1017 } 1018 if (r & SSH_WRITE_PENDING) { 1019 wr_handler = restart_coroutine; 1020 } 1021 1022 trace_ssh_co_yield(s->sock, rd_handler, wr_handler); 1023 1024 aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock, 1025 false, rd_handler, wr_handler, NULL, &restart); 1026 qemu_coroutine_yield(); 1027 trace_ssh_co_yield_back(s->sock); 1028 } 1029 1030 static coroutine_fn int ssh_read(BDRVSSHState *s, BlockDriverState *bs, 1031 int64_t offset, size_t size, 1032 QEMUIOVector *qiov) 1033 { 1034 ssize_t r; 1035 size_t got; 1036 char *buf, *end_of_vec; 1037 struct iovec *i; 1038 1039 trace_ssh_read(offset, size); 1040 1041 trace_ssh_seek(offset); 1042 sftp_seek64(s->sftp_handle, offset); 1043 1044 /* This keeps track of the current iovec element ('i'), where we 1045 * will write to next ('buf'), and the end of the current iovec 1046 * ('end_of_vec'). 1047 */ 1048 i = &qiov->iov[0]; 1049 buf = i->iov_base; 1050 end_of_vec = i->iov_base + i->iov_len; 1051 1052 for (got = 0; got < size; ) { 1053 size_t request_read_size; 1054 again: 1055 /* 1056 * The size of SFTP packets is limited to 32K bytes, so limit 1057 * the amount of data requested to 16K, as libssh currently 1058 * does not handle multiple requests on its own. 1059 */ 1060 request_read_size = MIN(end_of_vec - buf, 16384); 1061 trace_ssh_read_buf(buf, end_of_vec - buf, request_read_size); 1062 r = sftp_read(s->sftp_handle, buf, request_read_size); 1063 trace_ssh_read_return(r, sftp_get_error(s->sftp)); 1064 1065 if (r == SSH_AGAIN) { 1066 co_yield(s, bs); 1067 goto again; 1068 } 1069 if (r == SSH_EOF || (r == 0 && sftp_get_error(s->sftp) == SSH_FX_EOF)) { 1070 /* EOF: Short read so pad the buffer with zeroes and return it. */ 1071 qemu_iovec_memset(qiov, got, 0, size - got); 1072 return 0; 1073 } 1074 if (r <= 0) { 1075 sftp_error_trace(s, "read"); 1076 return -EIO; 1077 } 1078 1079 got += r; 1080 buf += r; 1081 if (buf >= end_of_vec && got < size) { 1082 i++; 1083 buf = i->iov_base; 1084 end_of_vec = i->iov_base + i->iov_len; 1085 } 1086 } 1087 1088 return 0; 1089 } 1090 1091 static coroutine_fn int ssh_co_readv(BlockDriverState *bs, 1092 int64_t sector_num, 1093 int nb_sectors, QEMUIOVector *qiov) 1094 { 1095 BDRVSSHState *s = bs->opaque; 1096 int ret; 1097 1098 qemu_co_mutex_lock(&s->lock); 1099 ret = ssh_read(s, bs, sector_num * BDRV_SECTOR_SIZE, 1100 nb_sectors * BDRV_SECTOR_SIZE, qiov); 1101 qemu_co_mutex_unlock(&s->lock); 1102 1103 return ret; 1104 } 1105 1106 static int ssh_write(BDRVSSHState *s, BlockDriverState *bs, 1107 int64_t offset, size_t size, 1108 QEMUIOVector *qiov) 1109 { 1110 ssize_t r; 1111 size_t written; 1112 char *buf, *end_of_vec; 1113 struct iovec *i; 1114 1115 trace_ssh_write(offset, size); 1116 1117 trace_ssh_seek(offset); 1118 sftp_seek64(s->sftp_handle, offset); 1119 1120 /* This keeps track of the current iovec element ('i'), where we 1121 * will read from next ('buf'), and the end of the current iovec 1122 * ('end_of_vec'). 1123 */ 1124 i = &qiov->iov[0]; 1125 buf = i->iov_base; 1126 end_of_vec = i->iov_base + i->iov_len; 1127 1128 for (written = 0; written < size; ) { 1129 size_t request_write_size; 1130 again: 1131 /* 1132 * Avoid too large data packets, as libssh currently does not 1133 * handle multiple requests on its own. 1134 */ 1135 request_write_size = MIN(end_of_vec - buf, 131072); 1136 trace_ssh_write_buf(buf, end_of_vec - buf, request_write_size); 1137 r = sftp_write(s->sftp_handle, buf, request_write_size); 1138 trace_ssh_write_return(r, sftp_get_error(s->sftp)); 1139 1140 if (r == SSH_AGAIN) { 1141 co_yield(s, bs); 1142 goto again; 1143 } 1144 if (r < 0) { 1145 sftp_error_trace(s, "write"); 1146 return -EIO; 1147 } 1148 1149 written += r; 1150 buf += r; 1151 if (buf >= end_of_vec && written < size) { 1152 i++; 1153 buf = i->iov_base; 1154 end_of_vec = i->iov_base + i->iov_len; 1155 } 1156 1157 if (offset + written > s->attrs->size) { 1158 s->attrs->size = offset + written; 1159 } 1160 } 1161 1162 return 0; 1163 } 1164 1165 static coroutine_fn int ssh_co_writev(BlockDriverState *bs, 1166 int64_t sector_num, 1167 int nb_sectors, QEMUIOVector *qiov, 1168 int flags) 1169 { 1170 BDRVSSHState *s = bs->opaque; 1171 int ret; 1172 1173 assert(!flags); 1174 qemu_co_mutex_lock(&s->lock); 1175 ret = ssh_write(s, bs, sector_num * BDRV_SECTOR_SIZE, 1176 nb_sectors * BDRV_SECTOR_SIZE, qiov); 1177 qemu_co_mutex_unlock(&s->lock); 1178 1179 return ret; 1180 } 1181 1182 static void unsafe_flush_warning(BDRVSSHState *s, const char *what) 1183 { 1184 if (!s->unsafe_flush_warning) { 1185 warn_report("ssh server %s does not support fsync", 1186 s->inet->host); 1187 if (what) { 1188 error_report("to support fsync, you need %s", what); 1189 } 1190 s->unsafe_flush_warning = true; 1191 } 1192 } 1193 1194 static coroutine_fn int ssh_flush(BDRVSSHState *s, BlockDriverState *bs) 1195 { 1196 int r; 1197 1198 trace_ssh_flush(); 1199 1200 if (!sftp_extension_supported(s->sftp, "fsync@openssh.com", "1")) { 1201 unsafe_flush_warning(s, "OpenSSH >= 6.3"); 1202 return 0; 1203 } 1204 again: 1205 r = sftp_fsync(s->sftp_handle); 1206 if (r == SSH_AGAIN) { 1207 co_yield(s, bs); 1208 goto again; 1209 } 1210 if (r < 0) { 1211 sftp_error_trace(s, "fsync"); 1212 return -EIO; 1213 } 1214 1215 return 0; 1216 } 1217 1218 static coroutine_fn int ssh_co_flush(BlockDriverState *bs) 1219 { 1220 BDRVSSHState *s = bs->opaque; 1221 int ret; 1222 1223 qemu_co_mutex_lock(&s->lock); 1224 ret = ssh_flush(s, bs); 1225 qemu_co_mutex_unlock(&s->lock); 1226 1227 return ret; 1228 } 1229 1230 static int64_t ssh_getlength(BlockDriverState *bs) 1231 { 1232 BDRVSSHState *s = bs->opaque; 1233 int64_t length; 1234 1235 /* Note we cannot make a libssh call here. */ 1236 length = (int64_t) s->attrs->size; 1237 trace_ssh_getlength(length); 1238 1239 return length; 1240 } 1241 1242 static int coroutine_fn ssh_co_truncate(BlockDriverState *bs, int64_t offset, 1243 bool exact, PreallocMode prealloc, 1244 BdrvRequestFlags flags, Error **errp) 1245 { 1246 BDRVSSHState *s = bs->opaque; 1247 1248 if (prealloc != PREALLOC_MODE_OFF) { 1249 error_setg(errp, "Unsupported preallocation mode '%s'", 1250 PreallocMode_str(prealloc)); 1251 return -ENOTSUP; 1252 } 1253 1254 if (offset < s->attrs->size) { 1255 error_setg(errp, "ssh driver does not support shrinking files"); 1256 return -ENOTSUP; 1257 } 1258 1259 if (offset == s->attrs->size) { 1260 return 0; 1261 } 1262 1263 return ssh_grow_file(s, offset, errp); 1264 } 1265 1266 static void ssh_refresh_filename(BlockDriverState *bs) 1267 { 1268 BDRVSSHState *s = bs->opaque; 1269 const char *path, *host_key_check; 1270 int ret; 1271 1272 /* 1273 * None of these options can be represented in a plain "host:port" 1274 * format, so if any was given, we have to abort. 1275 */ 1276 if (s->inet->has_ipv4 || s->inet->has_ipv6 || s->inet->has_to || 1277 s->inet->has_numeric) 1278 { 1279 return; 1280 } 1281 1282 path = qdict_get_try_str(bs->full_open_options, "path"); 1283 assert(path); /* mandatory option */ 1284 1285 host_key_check = qdict_get_try_str(bs->full_open_options, "host_key_check"); 1286 1287 ret = snprintf(bs->exact_filename, sizeof(bs->exact_filename), 1288 "ssh://%s@%s:%s%s%s%s", 1289 s->user, s->inet->host, s->inet->port, path, 1290 host_key_check ? "?host_key_check=" : "", 1291 host_key_check ?: ""); 1292 if (ret >= sizeof(bs->exact_filename)) { 1293 /* An overflow makes the filename unusable, so do not report any */ 1294 bs->exact_filename[0] = '\0'; 1295 } 1296 } 1297 1298 static char *ssh_bdrv_dirname(BlockDriverState *bs, Error **errp) 1299 { 1300 if (qdict_haskey(bs->full_open_options, "host_key_check")) { 1301 /* 1302 * We cannot generate a simple prefix if we would have to 1303 * append a query string. 1304 */ 1305 error_setg(errp, 1306 "Cannot generate a base directory with host_key_check set"); 1307 return NULL; 1308 } 1309 1310 if (bs->exact_filename[0] == '\0') { 1311 error_setg(errp, "Cannot generate a base directory for this ssh node"); 1312 return NULL; 1313 } 1314 1315 return path_combine(bs->exact_filename, ""); 1316 } 1317 1318 static const char *const ssh_strong_runtime_opts[] = { 1319 "host", 1320 "port", 1321 "path", 1322 "user", 1323 "host_key_check", 1324 "server.", 1325 1326 NULL 1327 }; 1328 1329 static BlockDriver bdrv_ssh = { 1330 .format_name = "ssh", 1331 .protocol_name = "ssh", 1332 .instance_size = sizeof(BDRVSSHState), 1333 .bdrv_parse_filename = ssh_parse_filename, 1334 .bdrv_file_open = ssh_file_open, 1335 .bdrv_co_create = ssh_co_create, 1336 .bdrv_co_create_opts = ssh_co_create_opts, 1337 .bdrv_close = ssh_close, 1338 .bdrv_has_zero_init = ssh_has_zero_init, 1339 .bdrv_co_readv = ssh_co_readv, 1340 .bdrv_co_writev = ssh_co_writev, 1341 .bdrv_getlength = ssh_getlength, 1342 .bdrv_co_truncate = ssh_co_truncate, 1343 .bdrv_co_flush_to_disk = ssh_co_flush, 1344 .bdrv_refresh_filename = ssh_refresh_filename, 1345 .bdrv_dirname = ssh_bdrv_dirname, 1346 .create_opts = &ssh_create_opts, 1347 .strong_runtime_opts = ssh_strong_runtime_opts, 1348 }; 1349 1350 static void bdrv_ssh_init(void) 1351 { 1352 int r; 1353 1354 r = ssh_init(); 1355 if (r != 0) { 1356 fprintf(stderr, "libssh initialization failed, %d\n", r); 1357 exit(EXIT_FAILURE); 1358 } 1359 1360 #if TRACE_LIBSSH != 0 1361 ssh_set_log_level(TRACE_LIBSSH); 1362 #endif 1363 1364 bdrv_register(&bdrv_ssh); 1365 } 1366 1367 block_init(bdrv_ssh_init); 1368