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