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 #ifdef HAVE_LIBSSH_0_8 281 enum ssh_known_hosts_e state; 282 int r; 283 ssh_key pubkey; 284 enum ssh_keytypes_e pubkey_type; 285 unsigned char *server_hash = NULL; 286 size_t server_hash_len; 287 char *fingerprint = NULL; 288 289 state = ssh_session_is_known_server(s->session); 290 trace_ssh_server_status(state); 291 292 switch (state) { 293 case SSH_KNOWN_HOSTS_OK: 294 /* OK */ 295 trace_ssh_check_host_key_knownhosts(); 296 break; 297 case SSH_KNOWN_HOSTS_CHANGED: 298 ret = -EINVAL; 299 r = ssh_get_server_publickey(s->session, &pubkey); 300 if (r == 0) { 301 r = ssh_get_publickey_hash(pubkey, SSH_PUBLICKEY_HASH_SHA256, 302 &server_hash, &server_hash_len); 303 pubkey_type = ssh_key_type(pubkey); 304 ssh_key_free(pubkey); 305 } 306 if (r == 0) { 307 fingerprint = ssh_get_fingerprint_hash(SSH_PUBLICKEY_HASH_SHA256, 308 server_hash, 309 server_hash_len); 310 ssh_clean_pubkey_hash(&server_hash); 311 } 312 if (fingerprint) { 313 error_setg(errp, 314 "host key (%s key with fingerprint %s) does not match " 315 "the one in known_hosts; this may be a possible attack", 316 ssh_key_type_to_char(pubkey_type), fingerprint); 317 ssh_string_free_char(fingerprint); 318 } else { 319 error_setg(errp, 320 "host key does not match the one in known_hosts; this " 321 "may be a possible attack"); 322 } 323 goto out; 324 case SSH_KNOWN_HOSTS_OTHER: 325 ret = -EINVAL; 326 error_setg(errp, 327 "host key for this server not found, another type exists"); 328 goto out; 329 case SSH_KNOWN_HOSTS_UNKNOWN: 330 ret = -EINVAL; 331 error_setg(errp, "no host key was found in known_hosts"); 332 goto out; 333 case SSH_KNOWN_HOSTS_NOT_FOUND: 334 ret = -ENOENT; 335 error_setg(errp, "known_hosts file not found"); 336 goto out; 337 case SSH_KNOWN_HOSTS_ERROR: 338 ret = -EINVAL; 339 error_setg(errp, "error while checking the host"); 340 goto out; 341 default: 342 ret = -EINVAL; 343 error_setg(errp, "error while checking for known server (%d)", state); 344 goto out; 345 } 346 #else /* !HAVE_LIBSSH_0_8 */ 347 int state; 348 349 state = ssh_is_server_known(s->session); 350 trace_ssh_server_status(state); 351 352 switch (state) { 353 case SSH_SERVER_KNOWN_OK: 354 /* OK */ 355 trace_ssh_check_host_key_knownhosts(); 356 break; 357 case SSH_SERVER_KNOWN_CHANGED: 358 ret = -EINVAL; 359 error_setg(errp, 360 "host key does not match the one in known_hosts; this " 361 "may be a possible attack"); 362 goto out; 363 case SSH_SERVER_FOUND_OTHER: 364 ret = -EINVAL; 365 error_setg(errp, 366 "host key for this server not found, another type exists"); 367 goto out; 368 case SSH_SERVER_FILE_NOT_FOUND: 369 ret = -ENOENT; 370 error_setg(errp, "known_hosts file not found"); 371 goto out; 372 case SSH_SERVER_NOT_KNOWN: 373 ret = -EINVAL; 374 error_setg(errp, "no host key was found in known_hosts"); 375 goto out; 376 case SSH_SERVER_ERROR: 377 ret = -EINVAL; 378 error_setg(errp, "server error"); 379 goto out; 380 default: 381 ret = -EINVAL; 382 error_setg(errp, "error while checking for known server (%d)", state); 383 goto out; 384 } 385 #endif /* !HAVE_LIBSSH_0_8 */ 386 387 /* known_hosts checking successful. */ 388 ret = 0; 389 390 out: 391 return ret; 392 } 393 394 static unsigned hex2decimal(char ch) 395 { 396 if (ch >= '0' && ch <= '9') { 397 return (ch - '0'); 398 } else if (ch >= 'a' && ch <= 'f') { 399 return 10 + (ch - 'a'); 400 } else if (ch >= 'A' && ch <= 'F') { 401 return 10 + (ch - 'A'); 402 } 403 404 return -1; 405 } 406 407 /* Compare the binary fingerprint (hash of host key) with the 408 * host_key_check parameter. 409 */ 410 static int compare_fingerprint(const unsigned char *fingerprint, size_t len, 411 const char *host_key_check) 412 { 413 unsigned c; 414 415 while (len > 0) { 416 while (*host_key_check == ':') 417 host_key_check++; 418 if (!qemu_isxdigit(host_key_check[0]) || 419 !qemu_isxdigit(host_key_check[1])) 420 return 1; 421 c = hex2decimal(host_key_check[0]) * 16 + 422 hex2decimal(host_key_check[1]); 423 if (c - *fingerprint != 0) 424 return c - *fingerprint; 425 fingerprint++; 426 len--; 427 host_key_check += 2; 428 } 429 return *host_key_check - '\0'; 430 } 431 432 static int 433 check_host_key_hash(BDRVSSHState *s, const char *hash, 434 enum ssh_publickey_hash_type type, Error **errp) 435 { 436 int r; 437 ssh_key pubkey; 438 unsigned char *server_hash; 439 size_t server_hash_len; 440 441 #ifdef HAVE_LIBSSH_0_8 442 r = ssh_get_server_publickey(s->session, &pubkey); 443 #else 444 r = ssh_get_publickey(s->session, &pubkey); 445 #endif 446 if (r != SSH_OK) { 447 session_error_setg(errp, s, "failed to read remote host key"); 448 return -EINVAL; 449 } 450 451 r = ssh_get_publickey_hash(pubkey, type, &server_hash, &server_hash_len); 452 ssh_key_free(pubkey); 453 if (r != 0) { 454 session_error_setg(errp, s, 455 "failed reading the hash of the server SSH key"); 456 return -EINVAL; 457 } 458 459 r = compare_fingerprint(server_hash, server_hash_len, hash); 460 ssh_clean_pubkey_hash(&server_hash); 461 if (r != 0) { 462 error_setg(errp, "remote host key does not match host_key_check '%s'", 463 hash); 464 return -EPERM; 465 } 466 467 return 0; 468 } 469 470 static int check_host_key(BDRVSSHState *s, SshHostKeyCheck *hkc, Error **errp) 471 { 472 SshHostKeyCheckMode mode; 473 474 if (hkc) { 475 mode = hkc->mode; 476 } else { 477 mode = SSH_HOST_KEY_CHECK_MODE_KNOWN_HOSTS; 478 } 479 480 switch (mode) { 481 case SSH_HOST_KEY_CHECK_MODE_NONE: 482 return 0; 483 case SSH_HOST_KEY_CHECK_MODE_HASH: 484 if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_MD5) { 485 return check_host_key_hash(s, hkc->u.hash.hash, 486 SSH_PUBLICKEY_HASH_MD5, errp); 487 } else if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_SHA1) { 488 return check_host_key_hash(s, hkc->u.hash.hash, 489 SSH_PUBLICKEY_HASH_SHA1, errp); 490 } 491 g_assert_not_reached(); 492 break; 493 case SSH_HOST_KEY_CHECK_MODE_KNOWN_HOSTS: 494 return check_host_key_knownhosts(s, errp); 495 default: 496 g_assert_not_reached(); 497 } 498 499 return -EINVAL; 500 } 501 502 static int authenticate(BDRVSSHState *s, Error **errp) 503 { 504 int r, ret; 505 int method; 506 507 /* Try to authenticate with the "none" method. */ 508 r = ssh_userauth_none(s->session, NULL); 509 if (r == SSH_AUTH_ERROR) { 510 ret = -EPERM; 511 session_error_setg(errp, s, "failed to authenticate using none " 512 "authentication"); 513 goto out; 514 } else if (r == SSH_AUTH_SUCCESS) { 515 /* Authenticated! */ 516 ret = 0; 517 goto out; 518 } 519 520 method = ssh_userauth_list(s->session, NULL); 521 trace_ssh_auth_methods(method); 522 523 /* 524 * Try to authenticate with publickey, using the ssh-agent 525 * if available. 526 */ 527 if (method & SSH_AUTH_METHOD_PUBLICKEY) { 528 r = ssh_userauth_publickey_auto(s->session, NULL, NULL); 529 if (r == SSH_AUTH_ERROR) { 530 ret = -EINVAL; 531 session_error_setg(errp, s, "failed to authenticate using " 532 "publickey authentication"); 533 goto out; 534 } else if (r == SSH_AUTH_SUCCESS) { 535 /* Authenticated! */ 536 ret = 0; 537 goto out; 538 } 539 } 540 541 ret = -EPERM; 542 error_setg(errp, "failed to authenticate using publickey authentication " 543 "and the identities held by your ssh-agent"); 544 545 out: 546 return ret; 547 } 548 549 static QemuOptsList ssh_runtime_opts = { 550 .name = "ssh", 551 .head = QTAILQ_HEAD_INITIALIZER(ssh_runtime_opts.head), 552 .desc = { 553 { 554 .name = "host", 555 .type = QEMU_OPT_STRING, 556 .help = "Host to connect to", 557 }, 558 { 559 .name = "port", 560 .type = QEMU_OPT_NUMBER, 561 .help = "Port to connect to", 562 }, 563 { 564 .name = "host_key_check", 565 .type = QEMU_OPT_STRING, 566 .help = "Defines how and what to check the host key against", 567 }, 568 { /* end of list */ } 569 }, 570 }; 571 572 static bool ssh_process_legacy_options(QDict *output_opts, 573 QemuOpts *legacy_opts, 574 Error **errp) 575 { 576 const char *host = qemu_opt_get(legacy_opts, "host"); 577 const char *port = qemu_opt_get(legacy_opts, "port"); 578 const char *host_key_check = qemu_opt_get(legacy_opts, "host_key_check"); 579 580 if (!host && port) { 581 error_setg(errp, "port may not be used without host"); 582 return false; 583 } 584 585 if (host) { 586 qdict_put_str(output_opts, "server.host", host); 587 qdict_put_str(output_opts, "server.port", port ?: stringify(22)); 588 } 589 590 if (host_key_check) { 591 if (strcmp(host_key_check, "no") == 0) { 592 qdict_put_str(output_opts, "host-key-check.mode", "none"); 593 } else if (strncmp(host_key_check, "md5:", 4) == 0) { 594 qdict_put_str(output_opts, "host-key-check.mode", "hash"); 595 qdict_put_str(output_opts, "host-key-check.type", "md5"); 596 qdict_put_str(output_opts, "host-key-check.hash", 597 &host_key_check[4]); 598 } else if (strncmp(host_key_check, "sha1:", 5) == 0) { 599 qdict_put_str(output_opts, "host-key-check.mode", "hash"); 600 qdict_put_str(output_opts, "host-key-check.type", "sha1"); 601 qdict_put_str(output_opts, "host-key-check.hash", 602 &host_key_check[5]); 603 } else if (strcmp(host_key_check, "yes") == 0) { 604 qdict_put_str(output_opts, "host-key-check.mode", "known_hosts"); 605 } else { 606 error_setg(errp, "unknown host_key_check setting (%s)", 607 host_key_check); 608 return false; 609 } 610 } 611 612 return true; 613 } 614 615 static BlockdevOptionsSsh *ssh_parse_options(QDict *options, Error **errp) 616 { 617 BlockdevOptionsSsh *result = NULL; 618 QemuOpts *opts = NULL; 619 Error *local_err = NULL; 620 const QDictEntry *e; 621 Visitor *v; 622 623 /* Translate legacy options */ 624 opts = qemu_opts_create(&ssh_runtime_opts, NULL, 0, &error_abort); 625 qemu_opts_absorb_qdict(opts, options, &local_err); 626 if (local_err) { 627 error_propagate(errp, local_err); 628 goto fail; 629 } 630 631 if (!ssh_process_legacy_options(options, opts, errp)) { 632 goto fail; 633 } 634 635 /* Create the QAPI object */ 636 v = qobject_input_visitor_new_flat_confused(options, errp); 637 if (!v) { 638 goto fail; 639 } 640 641 visit_type_BlockdevOptionsSsh(v, NULL, &result, &local_err); 642 visit_free(v); 643 644 if (local_err) { 645 error_propagate(errp, local_err); 646 goto fail; 647 } 648 649 /* Remove the processed options from the QDict (the visitor processes 650 * _all_ options in the QDict) */ 651 while ((e = qdict_first(options))) { 652 qdict_del(options, e->key); 653 } 654 655 fail: 656 qemu_opts_del(opts); 657 return result; 658 } 659 660 static int connect_to_ssh(BDRVSSHState *s, BlockdevOptionsSsh *opts, 661 int ssh_flags, int creat_mode, Error **errp) 662 { 663 int r, ret; 664 unsigned int port = 0; 665 int new_sock = -1; 666 667 if (opts->has_user) { 668 s->user = g_strdup(opts->user); 669 } else { 670 s->user = g_strdup(g_get_user_name()); 671 if (!s->user) { 672 error_setg_errno(errp, errno, "Can't get user name"); 673 ret = -errno; 674 goto err; 675 } 676 } 677 678 /* Pop the config into our state object, Exit if invalid */ 679 s->inet = opts->server; 680 opts->server = NULL; 681 682 if (qemu_strtoui(s->inet->port, NULL, 10, &port) < 0) { 683 error_setg(errp, "Use only numeric port value"); 684 ret = -EINVAL; 685 goto err; 686 } 687 688 /* Open the socket and connect. */ 689 new_sock = inet_connect_saddr(s->inet, errp); 690 if (new_sock < 0) { 691 ret = -EIO; 692 goto err; 693 } 694 695 /* 696 * Try to disable the Nagle algorithm on TCP sockets to reduce latency, 697 * but do not fail if it cannot be disabled. 698 */ 699 r = socket_set_nodelay(new_sock); 700 if (r < 0) { 701 warn_report("can't set TCP_NODELAY for the ssh server %s: %s", 702 s->inet->host, strerror(errno)); 703 } 704 705 /* Create SSH session. */ 706 s->session = ssh_new(); 707 if (!s->session) { 708 ret = -EINVAL; 709 session_error_setg(errp, s, "failed to initialize libssh session"); 710 goto err; 711 } 712 713 /* 714 * Make sure we are in blocking mode during the connection and 715 * authentication phases. 716 */ 717 ssh_set_blocking(s->session, 1); 718 719 r = ssh_options_set(s->session, SSH_OPTIONS_USER, s->user); 720 if (r < 0) { 721 ret = -EINVAL; 722 session_error_setg(errp, s, 723 "failed to set the user in the libssh session"); 724 goto err; 725 } 726 727 r = ssh_options_set(s->session, SSH_OPTIONS_HOST, s->inet->host); 728 if (r < 0) { 729 ret = -EINVAL; 730 session_error_setg(errp, s, 731 "failed to set the host in the libssh session"); 732 goto err; 733 } 734 735 if (port > 0) { 736 r = ssh_options_set(s->session, SSH_OPTIONS_PORT, &port); 737 if (r < 0) { 738 ret = -EINVAL; 739 session_error_setg(errp, s, 740 "failed to set the port in the libssh session"); 741 goto err; 742 } 743 } 744 745 r = ssh_options_set(s->session, SSH_OPTIONS_COMPRESSION, "none"); 746 if (r < 0) { 747 ret = -EINVAL; 748 session_error_setg(errp, s, 749 "failed to disable the compression in the libssh " 750 "session"); 751 goto err; 752 } 753 754 /* Read ~/.ssh/config. */ 755 r = ssh_options_parse_config(s->session, NULL); 756 if (r < 0) { 757 ret = -EINVAL; 758 session_error_setg(errp, s, "failed to parse ~/.ssh/config"); 759 goto err; 760 } 761 762 r = ssh_options_set(s->session, SSH_OPTIONS_FD, &new_sock); 763 if (r < 0) { 764 ret = -EINVAL; 765 session_error_setg(errp, s, 766 "failed to set the socket in the libssh session"); 767 goto err; 768 } 769 /* libssh took ownership of the socket. */ 770 s->sock = new_sock; 771 new_sock = -1; 772 773 /* Connect. */ 774 r = ssh_connect(s->session); 775 if (r != SSH_OK) { 776 ret = -EINVAL; 777 session_error_setg(errp, s, "failed to establish SSH session"); 778 goto err; 779 } 780 781 /* Check the remote host's key against known_hosts. */ 782 ret = check_host_key(s, opts->host_key_check, errp); 783 if (ret < 0) { 784 goto err; 785 } 786 787 /* Authenticate. */ 788 ret = authenticate(s, errp); 789 if (ret < 0) { 790 goto err; 791 } 792 793 /* Start SFTP. */ 794 s->sftp = sftp_new(s->session); 795 if (!s->sftp) { 796 session_error_setg(errp, s, "failed to create sftp handle"); 797 ret = -EINVAL; 798 goto err; 799 } 800 801 r = sftp_init(s->sftp); 802 if (r < 0) { 803 sftp_error_setg(errp, s, "failed to initialize sftp handle"); 804 ret = -EINVAL; 805 goto err; 806 } 807 808 /* Open the remote file. */ 809 trace_ssh_connect_to_ssh(opts->path, ssh_flags, creat_mode); 810 s->sftp_handle = sftp_open(s->sftp, opts->path, ssh_flags, creat_mode); 811 if (!s->sftp_handle) { 812 sftp_error_setg(errp, s, "failed to open remote file '%s'", 813 opts->path); 814 ret = -EINVAL; 815 goto err; 816 } 817 818 /* Make sure the SFTP file is handled in blocking mode. */ 819 sftp_file_set_blocking(s->sftp_handle); 820 821 s->attrs = sftp_fstat(s->sftp_handle); 822 if (!s->attrs) { 823 sftp_error_setg(errp, s, "failed to read file attributes"); 824 return -EINVAL; 825 } 826 827 return 0; 828 829 err: 830 if (s->attrs) { 831 sftp_attributes_free(s->attrs); 832 } 833 s->attrs = NULL; 834 if (s->sftp_handle) { 835 sftp_close(s->sftp_handle); 836 } 837 s->sftp_handle = NULL; 838 if (s->sftp) { 839 sftp_free(s->sftp); 840 } 841 s->sftp = NULL; 842 if (s->session) { 843 ssh_disconnect(s->session); 844 ssh_free(s->session); 845 } 846 s->session = NULL; 847 s->sock = -1; 848 if (new_sock >= 0) { 849 close(new_sock); 850 } 851 852 return ret; 853 } 854 855 static int ssh_file_open(BlockDriverState *bs, QDict *options, int bdrv_flags, 856 Error **errp) 857 { 858 BDRVSSHState *s = bs->opaque; 859 BlockdevOptionsSsh *opts; 860 int ret; 861 int ssh_flags; 862 863 ssh_state_init(s); 864 865 ssh_flags = 0; 866 if (bdrv_flags & BDRV_O_RDWR) { 867 ssh_flags |= O_RDWR; 868 } else { 869 ssh_flags |= O_RDONLY; 870 } 871 872 opts = ssh_parse_options(options, errp); 873 if (opts == NULL) { 874 return -EINVAL; 875 } 876 877 /* Start up SSH. */ 878 ret = connect_to_ssh(s, opts, ssh_flags, 0, errp); 879 if (ret < 0) { 880 goto err; 881 } 882 883 /* Go non-blocking. */ 884 ssh_set_blocking(s->session, 0); 885 886 qapi_free_BlockdevOptionsSsh(opts); 887 888 return 0; 889 890 err: 891 qapi_free_BlockdevOptionsSsh(opts); 892 893 return ret; 894 } 895 896 /* Note: This is a blocking operation */ 897 static int ssh_grow_file(BDRVSSHState *s, int64_t offset, Error **errp) 898 { 899 ssize_t ret; 900 char c[1] = { '\0' }; 901 int was_blocking = ssh_is_blocking(s->session); 902 903 /* offset must be strictly greater than the current size so we do 904 * not overwrite anything */ 905 assert(offset > 0 && offset > s->attrs->size); 906 907 ssh_set_blocking(s->session, 1); 908 909 sftp_seek64(s->sftp_handle, offset - 1); 910 ret = sftp_write(s->sftp_handle, c, 1); 911 912 ssh_set_blocking(s->session, was_blocking); 913 914 if (ret < 0) { 915 sftp_error_setg(errp, s, "Failed to grow file"); 916 return -EIO; 917 } 918 919 s->attrs->size = offset; 920 return 0; 921 } 922 923 static QemuOptsList ssh_create_opts = { 924 .name = "ssh-create-opts", 925 .head = QTAILQ_HEAD_INITIALIZER(ssh_create_opts.head), 926 .desc = { 927 { 928 .name = BLOCK_OPT_SIZE, 929 .type = QEMU_OPT_SIZE, 930 .help = "Virtual disk size" 931 }, 932 { /* end of list */ } 933 } 934 }; 935 936 static int ssh_co_create(BlockdevCreateOptions *options, Error **errp) 937 { 938 BlockdevCreateOptionsSsh *opts = &options->u.ssh; 939 BDRVSSHState s; 940 int ret; 941 942 assert(options->driver == BLOCKDEV_DRIVER_SSH); 943 944 ssh_state_init(&s); 945 946 ret = connect_to_ssh(&s, opts->location, 947 O_RDWR | O_CREAT | O_TRUNC, 948 0644, errp); 949 if (ret < 0) { 950 goto fail; 951 } 952 953 if (opts->size > 0) { 954 ret = ssh_grow_file(&s, opts->size, errp); 955 if (ret < 0) { 956 goto fail; 957 } 958 } 959 960 ret = 0; 961 fail: 962 ssh_state_free(&s); 963 return ret; 964 } 965 966 static int coroutine_fn ssh_co_create_opts(const char *filename, QemuOpts *opts, 967 Error **errp) 968 { 969 BlockdevCreateOptions *create_options; 970 BlockdevCreateOptionsSsh *ssh_opts; 971 int ret; 972 QDict *uri_options = NULL; 973 974 create_options = g_new0(BlockdevCreateOptions, 1); 975 create_options->driver = BLOCKDEV_DRIVER_SSH; 976 ssh_opts = &create_options->u.ssh; 977 978 /* Get desired file size. */ 979 ssh_opts->size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0), 980 BDRV_SECTOR_SIZE); 981 trace_ssh_co_create_opts(ssh_opts->size); 982 983 uri_options = qdict_new(); 984 ret = parse_uri(filename, uri_options, errp); 985 if (ret < 0) { 986 goto out; 987 } 988 989 ssh_opts->location = ssh_parse_options(uri_options, errp); 990 if (ssh_opts->location == NULL) { 991 ret = -EINVAL; 992 goto out; 993 } 994 995 ret = ssh_co_create(create_options, errp); 996 997 out: 998 qobject_unref(uri_options); 999 qapi_free_BlockdevCreateOptions(create_options); 1000 return ret; 1001 } 1002 1003 static void ssh_close(BlockDriverState *bs) 1004 { 1005 BDRVSSHState *s = bs->opaque; 1006 1007 ssh_state_free(s); 1008 } 1009 1010 static int ssh_has_zero_init(BlockDriverState *bs) 1011 { 1012 BDRVSSHState *s = bs->opaque; 1013 /* Assume false, unless we can positively prove it's true. */ 1014 int has_zero_init = 0; 1015 1016 if (s->attrs->type == SSH_FILEXFER_TYPE_REGULAR) { 1017 has_zero_init = 1; 1018 } 1019 1020 return has_zero_init; 1021 } 1022 1023 typedef struct BDRVSSHRestart { 1024 BlockDriverState *bs; 1025 Coroutine *co; 1026 } BDRVSSHRestart; 1027 1028 static void restart_coroutine(void *opaque) 1029 { 1030 BDRVSSHRestart *restart = opaque; 1031 BlockDriverState *bs = restart->bs; 1032 BDRVSSHState *s = bs->opaque; 1033 AioContext *ctx = bdrv_get_aio_context(bs); 1034 1035 trace_ssh_restart_coroutine(restart->co); 1036 aio_set_fd_handler(ctx, s->sock, false, NULL, NULL, NULL, NULL); 1037 1038 aio_co_wake(restart->co); 1039 } 1040 1041 /* A non-blocking call returned EAGAIN, so yield, ensuring the 1042 * handlers are set up so that we'll be rescheduled when there is an 1043 * interesting event on the socket. 1044 */ 1045 static coroutine_fn void co_yield(BDRVSSHState *s, BlockDriverState *bs) 1046 { 1047 int r; 1048 IOHandler *rd_handler = NULL, *wr_handler = NULL; 1049 BDRVSSHRestart restart = { 1050 .bs = bs, 1051 .co = qemu_coroutine_self() 1052 }; 1053 1054 r = ssh_get_poll_flags(s->session); 1055 1056 if (r & SSH_READ_PENDING) { 1057 rd_handler = restart_coroutine; 1058 } 1059 if (r & SSH_WRITE_PENDING) { 1060 wr_handler = restart_coroutine; 1061 } 1062 1063 trace_ssh_co_yield(s->sock, rd_handler, wr_handler); 1064 1065 aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock, 1066 false, rd_handler, wr_handler, NULL, &restart); 1067 qemu_coroutine_yield(); 1068 trace_ssh_co_yield_back(s->sock); 1069 } 1070 1071 static coroutine_fn int ssh_read(BDRVSSHState *s, BlockDriverState *bs, 1072 int64_t offset, size_t size, 1073 QEMUIOVector *qiov) 1074 { 1075 ssize_t r; 1076 size_t got; 1077 char *buf, *end_of_vec; 1078 struct iovec *i; 1079 1080 trace_ssh_read(offset, size); 1081 1082 trace_ssh_seek(offset); 1083 sftp_seek64(s->sftp_handle, offset); 1084 1085 /* This keeps track of the current iovec element ('i'), where we 1086 * will write to next ('buf'), and the end of the current iovec 1087 * ('end_of_vec'). 1088 */ 1089 i = &qiov->iov[0]; 1090 buf = i->iov_base; 1091 end_of_vec = i->iov_base + i->iov_len; 1092 1093 for (got = 0; got < size; ) { 1094 size_t request_read_size; 1095 again: 1096 /* 1097 * The size of SFTP packets is limited to 32K bytes, so limit 1098 * the amount of data requested to 16K, as libssh currently 1099 * does not handle multiple requests on its own. 1100 */ 1101 request_read_size = MIN(end_of_vec - buf, 16384); 1102 trace_ssh_read_buf(buf, end_of_vec - buf, request_read_size); 1103 r = sftp_read(s->sftp_handle, buf, request_read_size); 1104 trace_ssh_read_return(r, sftp_get_error(s->sftp)); 1105 1106 if (r == SSH_AGAIN) { 1107 co_yield(s, bs); 1108 goto again; 1109 } 1110 if (r == SSH_EOF || (r == 0 && sftp_get_error(s->sftp) == SSH_FX_EOF)) { 1111 /* EOF: Short read so pad the buffer with zeroes and return it. */ 1112 qemu_iovec_memset(qiov, got, 0, size - got); 1113 return 0; 1114 } 1115 if (r <= 0) { 1116 sftp_error_trace(s, "read"); 1117 return -EIO; 1118 } 1119 1120 got += r; 1121 buf += r; 1122 if (buf >= end_of_vec && got < size) { 1123 i++; 1124 buf = i->iov_base; 1125 end_of_vec = i->iov_base + i->iov_len; 1126 } 1127 } 1128 1129 return 0; 1130 } 1131 1132 static coroutine_fn int ssh_co_readv(BlockDriverState *bs, 1133 int64_t sector_num, 1134 int nb_sectors, QEMUIOVector *qiov) 1135 { 1136 BDRVSSHState *s = bs->opaque; 1137 int ret; 1138 1139 qemu_co_mutex_lock(&s->lock); 1140 ret = ssh_read(s, bs, sector_num * BDRV_SECTOR_SIZE, 1141 nb_sectors * BDRV_SECTOR_SIZE, qiov); 1142 qemu_co_mutex_unlock(&s->lock); 1143 1144 return ret; 1145 } 1146 1147 static int ssh_write(BDRVSSHState *s, BlockDriverState *bs, 1148 int64_t offset, size_t size, 1149 QEMUIOVector *qiov) 1150 { 1151 ssize_t r; 1152 size_t written; 1153 char *buf, *end_of_vec; 1154 struct iovec *i; 1155 1156 trace_ssh_write(offset, size); 1157 1158 trace_ssh_seek(offset); 1159 sftp_seek64(s->sftp_handle, offset); 1160 1161 /* This keeps track of the current iovec element ('i'), where we 1162 * will read from next ('buf'), and the end of the current iovec 1163 * ('end_of_vec'). 1164 */ 1165 i = &qiov->iov[0]; 1166 buf = i->iov_base; 1167 end_of_vec = i->iov_base + i->iov_len; 1168 1169 for (written = 0; written < size; ) { 1170 size_t request_write_size; 1171 again: 1172 /* 1173 * Avoid too large data packets, as libssh currently does not 1174 * handle multiple requests on its own. 1175 */ 1176 request_write_size = MIN(end_of_vec - buf, 131072); 1177 trace_ssh_write_buf(buf, end_of_vec - buf, request_write_size); 1178 r = sftp_write(s->sftp_handle, buf, request_write_size); 1179 trace_ssh_write_return(r, sftp_get_error(s->sftp)); 1180 1181 if (r == SSH_AGAIN) { 1182 co_yield(s, bs); 1183 goto again; 1184 } 1185 if (r < 0) { 1186 sftp_error_trace(s, "write"); 1187 return -EIO; 1188 } 1189 1190 written += r; 1191 buf += r; 1192 if (buf >= end_of_vec && written < size) { 1193 i++; 1194 buf = i->iov_base; 1195 end_of_vec = i->iov_base + i->iov_len; 1196 } 1197 1198 if (offset + written > s->attrs->size) { 1199 s->attrs->size = offset + written; 1200 } 1201 } 1202 1203 return 0; 1204 } 1205 1206 static coroutine_fn int ssh_co_writev(BlockDriverState *bs, 1207 int64_t sector_num, 1208 int nb_sectors, QEMUIOVector *qiov, 1209 int flags) 1210 { 1211 BDRVSSHState *s = bs->opaque; 1212 int ret; 1213 1214 assert(!flags); 1215 qemu_co_mutex_lock(&s->lock); 1216 ret = ssh_write(s, bs, sector_num * BDRV_SECTOR_SIZE, 1217 nb_sectors * BDRV_SECTOR_SIZE, qiov); 1218 qemu_co_mutex_unlock(&s->lock); 1219 1220 return ret; 1221 } 1222 1223 static void unsafe_flush_warning(BDRVSSHState *s, const char *what) 1224 { 1225 if (!s->unsafe_flush_warning) { 1226 warn_report("ssh server %s does not support fsync", 1227 s->inet->host); 1228 if (what) { 1229 error_report("to support fsync, you need %s", what); 1230 } 1231 s->unsafe_flush_warning = true; 1232 } 1233 } 1234 1235 #ifdef HAVE_LIBSSH_0_8 1236 1237 static coroutine_fn int ssh_flush(BDRVSSHState *s, BlockDriverState *bs) 1238 { 1239 int r; 1240 1241 trace_ssh_flush(); 1242 1243 if (!sftp_extension_supported(s->sftp, "fsync@openssh.com", "1")) { 1244 unsafe_flush_warning(s, "OpenSSH >= 6.3"); 1245 return 0; 1246 } 1247 again: 1248 r = sftp_fsync(s->sftp_handle); 1249 if (r == SSH_AGAIN) { 1250 co_yield(s, bs); 1251 goto again; 1252 } 1253 if (r < 0) { 1254 sftp_error_trace(s, "fsync"); 1255 return -EIO; 1256 } 1257 1258 return 0; 1259 } 1260 1261 static coroutine_fn int ssh_co_flush(BlockDriverState *bs) 1262 { 1263 BDRVSSHState *s = bs->opaque; 1264 int ret; 1265 1266 qemu_co_mutex_lock(&s->lock); 1267 ret = ssh_flush(s, bs); 1268 qemu_co_mutex_unlock(&s->lock); 1269 1270 return ret; 1271 } 1272 1273 #else /* !HAVE_LIBSSH_0_8 */ 1274 1275 static coroutine_fn int ssh_co_flush(BlockDriverState *bs) 1276 { 1277 BDRVSSHState *s = bs->opaque; 1278 1279 unsafe_flush_warning(s, "libssh >= 0.8.0"); 1280 return 0; 1281 } 1282 1283 #endif /* !HAVE_LIBSSH_0_8 */ 1284 1285 static int64_t ssh_getlength(BlockDriverState *bs) 1286 { 1287 BDRVSSHState *s = bs->opaque; 1288 int64_t length; 1289 1290 /* Note we cannot make a libssh call here. */ 1291 length = (int64_t) s->attrs->size; 1292 trace_ssh_getlength(length); 1293 1294 return length; 1295 } 1296 1297 static int coroutine_fn ssh_co_truncate(BlockDriverState *bs, int64_t offset, 1298 PreallocMode prealloc, Error **errp) 1299 { 1300 BDRVSSHState *s = bs->opaque; 1301 1302 if (prealloc != PREALLOC_MODE_OFF) { 1303 error_setg(errp, "Unsupported preallocation mode '%s'", 1304 PreallocMode_str(prealloc)); 1305 return -ENOTSUP; 1306 } 1307 1308 if (offset < s->attrs->size) { 1309 error_setg(errp, "ssh driver does not support shrinking files"); 1310 return -ENOTSUP; 1311 } 1312 1313 if (offset == s->attrs->size) { 1314 return 0; 1315 } 1316 1317 return ssh_grow_file(s, offset, errp); 1318 } 1319 1320 static void ssh_refresh_filename(BlockDriverState *bs) 1321 { 1322 BDRVSSHState *s = bs->opaque; 1323 const char *path, *host_key_check; 1324 int ret; 1325 1326 /* 1327 * None of these options can be represented in a plain "host:port" 1328 * format, so if any was given, we have to abort. 1329 */ 1330 if (s->inet->has_ipv4 || s->inet->has_ipv6 || s->inet->has_to || 1331 s->inet->has_numeric) 1332 { 1333 return; 1334 } 1335 1336 path = qdict_get_try_str(bs->full_open_options, "path"); 1337 assert(path); /* mandatory option */ 1338 1339 host_key_check = qdict_get_try_str(bs->full_open_options, "host_key_check"); 1340 1341 ret = snprintf(bs->exact_filename, sizeof(bs->exact_filename), 1342 "ssh://%s@%s:%s%s%s%s", 1343 s->user, s->inet->host, s->inet->port, path, 1344 host_key_check ? "?host_key_check=" : "", 1345 host_key_check ?: ""); 1346 if (ret >= sizeof(bs->exact_filename)) { 1347 /* An overflow makes the filename unusable, so do not report any */ 1348 bs->exact_filename[0] = '\0'; 1349 } 1350 } 1351 1352 static char *ssh_bdrv_dirname(BlockDriverState *bs, Error **errp) 1353 { 1354 if (qdict_haskey(bs->full_open_options, "host_key_check")) { 1355 /* 1356 * We cannot generate a simple prefix if we would have to 1357 * append a query string. 1358 */ 1359 error_setg(errp, 1360 "Cannot generate a base directory with host_key_check set"); 1361 return NULL; 1362 } 1363 1364 if (bs->exact_filename[0] == '\0') { 1365 error_setg(errp, "Cannot generate a base directory for this ssh node"); 1366 return NULL; 1367 } 1368 1369 return path_combine(bs->exact_filename, ""); 1370 } 1371 1372 static const char *const ssh_strong_runtime_opts[] = { 1373 "host", 1374 "port", 1375 "path", 1376 "user", 1377 "host_key_check", 1378 "server.", 1379 1380 NULL 1381 }; 1382 1383 static BlockDriver bdrv_ssh = { 1384 .format_name = "ssh", 1385 .protocol_name = "ssh", 1386 .instance_size = sizeof(BDRVSSHState), 1387 .bdrv_parse_filename = ssh_parse_filename, 1388 .bdrv_file_open = ssh_file_open, 1389 .bdrv_co_create = ssh_co_create, 1390 .bdrv_co_create_opts = ssh_co_create_opts, 1391 .bdrv_close = ssh_close, 1392 .bdrv_has_zero_init = ssh_has_zero_init, 1393 .bdrv_has_zero_init_truncate = ssh_has_zero_init, 1394 .bdrv_co_readv = ssh_co_readv, 1395 .bdrv_co_writev = ssh_co_writev, 1396 .bdrv_getlength = ssh_getlength, 1397 .bdrv_co_truncate = ssh_co_truncate, 1398 .bdrv_co_flush_to_disk = ssh_co_flush, 1399 .bdrv_refresh_filename = ssh_refresh_filename, 1400 .bdrv_dirname = ssh_bdrv_dirname, 1401 .create_opts = &ssh_create_opts, 1402 .strong_runtime_opts = ssh_strong_runtime_opts, 1403 }; 1404 1405 static void bdrv_ssh_init(void) 1406 { 1407 int r; 1408 1409 r = ssh_init(); 1410 if (r != 0) { 1411 fprintf(stderr, "libssh initialization failed, %d\n", r); 1412 exit(EXIT_FAILURE); 1413 } 1414 1415 #if TRACE_LIBSSH != 0 1416 ssh_set_log_level(TRACE_LIBSSH); 1417 #endif 1418 1419 bdrv_register(&bdrv_ssh); 1420 } 1421 1422 block_init(bdrv_ssh_init); 1423