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 const QDictEntry *e; 620 Visitor *v; 621 622 /* Translate legacy options */ 623 opts = qemu_opts_create(&ssh_runtime_opts, NULL, 0, &error_abort); 624 if (!qemu_opts_absorb_qdict(opts, options, errp)) { 625 goto fail; 626 } 627 628 if (!ssh_process_legacy_options(options, opts, errp)) { 629 goto fail; 630 } 631 632 /* Create the QAPI object */ 633 v = qobject_input_visitor_new_flat_confused(options, errp); 634 if (!v) { 635 goto fail; 636 } 637 638 visit_type_BlockdevOptionsSsh(v, NULL, &result, errp); 639 visit_free(v); 640 if (!result) { 641 goto fail; 642 } 643 644 /* Remove the processed options from the QDict (the visitor processes 645 * _all_ options in the QDict) */ 646 while ((e = qdict_first(options))) { 647 qdict_del(options, e->key); 648 } 649 650 fail: 651 qemu_opts_del(opts); 652 return result; 653 } 654 655 static int connect_to_ssh(BDRVSSHState *s, BlockdevOptionsSsh *opts, 656 int ssh_flags, int creat_mode, Error **errp) 657 { 658 int r, ret; 659 unsigned int port = 0; 660 int new_sock = -1; 661 662 if (opts->has_user) { 663 s->user = g_strdup(opts->user); 664 } else { 665 s->user = g_strdup(g_get_user_name()); 666 if (!s->user) { 667 error_setg_errno(errp, errno, "Can't get user name"); 668 ret = -errno; 669 goto err; 670 } 671 } 672 673 /* Pop the config into our state object, Exit if invalid */ 674 s->inet = opts->server; 675 opts->server = NULL; 676 677 if (qemu_strtoui(s->inet->port, NULL, 10, &port) < 0) { 678 error_setg(errp, "Use only numeric port value"); 679 ret = -EINVAL; 680 goto err; 681 } 682 683 /* Open the socket and connect. */ 684 new_sock = inet_connect_saddr(s->inet, errp); 685 if (new_sock < 0) { 686 ret = -EIO; 687 goto err; 688 } 689 690 /* 691 * Try to disable the Nagle algorithm on TCP sockets to reduce latency, 692 * but do not fail if it cannot be disabled. 693 */ 694 r = socket_set_nodelay(new_sock); 695 if (r < 0) { 696 warn_report("can't set TCP_NODELAY for the ssh server %s: %s", 697 s->inet->host, strerror(errno)); 698 } 699 700 /* Create SSH session. */ 701 s->session = ssh_new(); 702 if (!s->session) { 703 ret = -EINVAL; 704 session_error_setg(errp, s, "failed to initialize libssh session"); 705 goto err; 706 } 707 708 /* 709 * Make sure we are in blocking mode during the connection and 710 * authentication phases. 711 */ 712 ssh_set_blocking(s->session, 1); 713 714 r = ssh_options_set(s->session, SSH_OPTIONS_USER, s->user); 715 if (r < 0) { 716 ret = -EINVAL; 717 session_error_setg(errp, s, 718 "failed to set the user in the libssh session"); 719 goto err; 720 } 721 722 r = ssh_options_set(s->session, SSH_OPTIONS_HOST, s->inet->host); 723 if (r < 0) { 724 ret = -EINVAL; 725 session_error_setg(errp, s, 726 "failed to set the host in the libssh session"); 727 goto err; 728 } 729 730 if (port > 0) { 731 r = ssh_options_set(s->session, SSH_OPTIONS_PORT, &port); 732 if (r < 0) { 733 ret = -EINVAL; 734 session_error_setg(errp, s, 735 "failed to set the port in the libssh session"); 736 goto err; 737 } 738 } 739 740 r = ssh_options_set(s->session, SSH_OPTIONS_COMPRESSION, "none"); 741 if (r < 0) { 742 ret = -EINVAL; 743 session_error_setg(errp, s, 744 "failed to disable the compression in the libssh " 745 "session"); 746 goto err; 747 } 748 749 /* Read ~/.ssh/config. */ 750 r = ssh_options_parse_config(s->session, NULL); 751 if (r < 0) { 752 ret = -EINVAL; 753 session_error_setg(errp, s, "failed to parse ~/.ssh/config"); 754 goto err; 755 } 756 757 r = ssh_options_set(s->session, SSH_OPTIONS_FD, &new_sock); 758 if (r < 0) { 759 ret = -EINVAL; 760 session_error_setg(errp, s, 761 "failed to set the socket in the libssh session"); 762 goto err; 763 } 764 /* libssh took ownership of the socket. */ 765 s->sock = new_sock; 766 new_sock = -1; 767 768 /* Connect. */ 769 r = ssh_connect(s->session); 770 if (r != SSH_OK) { 771 ret = -EINVAL; 772 session_error_setg(errp, s, "failed to establish SSH session"); 773 goto err; 774 } 775 776 /* Check the remote host's key against known_hosts. */ 777 ret = check_host_key(s, opts->host_key_check, errp); 778 if (ret < 0) { 779 goto err; 780 } 781 782 /* Authenticate. */ 783 ret = authenticate(s, errp); 784 if (ret < 0) { 785 goto err; 786 } 787 788 /* Start SFTP. */ 789 s->sftp = sftp_new(s->session); 790 if (!s->sftp) { 791 session_error_setg(errp, s, "failed to create sftp handle"); 792 ret = -EINVAL; 793 goto err; 794 } 795 796 r = sftp_init(s->sftp); 797 if (r < 0) { 798 sftp_error_setg(errp, s, "failed to initialize sftp handle"); 799 ret = -EINVAL; 800 goto err; 801 } 802 803 /* Open the remote file. */ 804 trace_ssh_connect_to_ssh(opts->path, ssh_flags, creat_mode); 805 s->sftp_handle = sftp_open(s->sftp, opts->path, ssh_flags, creat_mode); 806 if (!s->sftp_handle) { 807 sftp_error_setg(errp, s, "failed to open remote file '%s'", 808 opts->path); 809 ret = -EINVAL; 810 goto err; 811 } 812 813 /* Make sure the SFTP file is handled in blocking mode. */ 814 sftp_file_set_blocking(s->sftp_handle); 815 816 s->attrs = sftp_fstat(s->sftp_handle); 817 if (!s->attrs) { 818 sftp_error_setg(errp, s, "failed to read file attributes"); 819 return -EINVAL; 820 } 821 822 return 0; 823 824 err: 825 if (s->attrs) { 826 sftp_attributes_free(s->attrs); 827 } 828 s->attrs = NULL; 829 if (s->sftp_handle) { 830 sftp_close(s->sftp_handle); 831 } 832 s->sftp_handle = NULL; 833 if (s->sftp) { 834 sftp_free(s->sftp); 835 } 836 s->sftp = NULL; 837 if (s->session) { 838 ssh_disconnect(s->session); 839 ssh_free(s->session); 840 } 841 s->session = NULL; 842 s->sock = -1; 843 if (new_sock >= 0) { 844 close(new_sock); 845 } 846 847 return ret; 848 } 849 850 static int ssh_file_open(BlockDriverState *bs, QDict *options, int bdrv_flags, 851 Error **errp) 852 { 853 BDRVSSHState *s = bs->opaque; 854 BlockdevOptionsSsh *opts; 855 int ret; 856 int ssh_flags; 857 858 ssh_state_init(s); 859 860 ssh_flags = 0; 861 if (bdrv_flags & BDRV_O_RDWR) { 862 ssh_flags |= O_RDWR; 863 } else { 864 ssh_flags |= O_RDONLY; 865 } 866 867 opts = ssh_parse_options(options, errp); 868 if (opts == NULL) { 869 return -EINVAL; 870 } 871 872 /* Start up SSH. */ 873 ret = connect_to_ssh(s, opts, ssh_flags, 0, errp); 874 if (ret < 0) { 875 goto err; 876 } 877 878 /* Go non-blocking. */ 879 ssh_set_blocking(s->session, 0); 880 881 if (s->attrs->type == SSH_FILEXFER_TYPE_REGULAR) { 882 bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE; 883 } 884 885 qapi_free_BlockdevOptionsSsh(opts); 886 887 return 0; 888 889 err: 890 qapi_free_BlockdevOptionsSsh(opts); 891 892 return ret; 893 } 894 895 /* Note: This is a blocking operation */ 896 static int ssh_grow_file(BDRVSSHState *s, int64_t offset, Error **errp) 897 { 898 ssize_t ret; 899 char c[1] = { '\0' }; 900 int was_blocking = ssh_is_blocking(s->session); 901 902 /* offset must be strictly greater than the current size so we do 903 * not overwrite anything */ 904 assert(offset > 0 && offset > s->attrs->size); 905 906 ssh_set_blocking(s->session, 1); 907 908 sftp_seek64(s->sftp_handle, offset - 1); 909 ret = sftp_write(s->sftp_handle, c, 1); 910 911 ssh_set_blocking(s->session, was_blocking); 912 913 if (ret < 0) { 914 sftp_error_setg(errp, s, "Failed to grow file"); 915 return -EIO; 916 } 917 918 s->attrs->size = offset; 919 return 0; 920 } 921 922 static QemuOptsList ssh_create_opts = { 923 .name = "ssh-create-opts", 924 .head = QTAILQ_HEAD_INITIALIZER(ssh_create_opts.head), 925 .desc = { 926 { 927 .name = BLOCK_OPT_SIZE, 928 .type = QEMU_OPT_SIZE, 929 .help = "Virtual disk size" 930 }, 931 { /* end of list */ } 932 } 933 }; 934 935 static int ssh_co_create(BlockdevCreateOptions *options, Error **errp) 936 { 937 BlockdevCreateOptionsSsh *opts = &options->u.ssh; 938 BDRVSSHState s; 939 int ret; 940 941 assert(options->driver == BLOCKDEV_DRIVER_SSH); 942 943 ssh_state_init(&s); 944 945 ret = connect_to_ssh(&s, opts->location, 946 O_RDWR | O_CREAT | O_TRUNC, 947 0644, errp); 948 if (ret < 0) { 949 goto fail; 950 } 951 952 if (opts->size > 0) { 953 ret = ssh_grow_file(&s, opts->size, errp); 954 if (ret < 0) { 955 goto fail; 956 } 957 } 958 959 ret = 0; 960 fail: 961 ssh_state_free(&s); 962 return ret; 963 } 964 965 static int coroutine_fn ssh_co_create_opts(BlockDriver *drv, 966 const char *filename, 967 QemuOpts *opts, 968 Error **errp) 969 { 970 BlockdevCreateOptions *create_options; 971 BlockdevCreateOptionsSsh *ssh_opts; 972 int ret; 973 QDict *uri_options = NULL; 974 975 create_options = g_new0(BlockdevCreateOptions, 1); 976 create_options->driver = BLOCKDEV_DRIVER_SSH; 977 ssh_opts = &create_options->u.ssh; 978 979 /* Get desired file size. */ 980 ssh_opts->size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0), 981 BDRV_SECTOR_SIZE); 982 trace_ssh_co_create_opts(ssh_opts->size); 983 984 uri_options = qdict_new(); 985 ret = parse_uri(filename, uri_options, errp); 986 if (ret < 0) { 987 goto out; 988 } 989 990 ssh_opts->location = ssh_parse_options(uri_options, errp); 991 if (ssh_opts->location == NULL) { 992 ret = -EINVAL; 993 goto out; 994 } 995 996 ret = ssh_co_create(create_options, errp); 997 998 out: 999 qobject_unref(uri_options); 1000 qapi_free_BlockdevCreateOptions(create_options); 1001 return ret; 1002 } 1003 1004 static void ssh_close(BlockDriverState *bs) 1005 { 1006 BDRVSSHState *s = bs->opaque; 1007 1008 ssh_state_free(s); 1009 } 1010 1011 static int ssh_has_zero_init(BlockDriverState *bs) 1012 { 1013 BDRVSSHState *s = bs->opaque; 1014 /* Assume false, unless we can positively prove it's true. */ 1015 int has_zero_init = 0; 1016 1017 if (s->attrs->type == SSH_FILEXFER_TYPE_REGULAR) { 1018 has_zero_init = 1; 1019 } 1020 1021 return has_zero_init; 1022 } 1023 1024 typedef struct BDRVSSHRestart { 1025 BlockDriverState *bs; 1026 Coroutine *co; 1027 } BDRVSSHRestart; 1028 1029 static void restart_coroutine(void *opaque) 1030 { 1031 BDRVSSHRestart *restart = opaque; 1032 BlockDriverState *bs = restart->bs; 1033 BDRVSSHState *s = bs->opaque; 1034 AioContext *ctx = bdrv_get_aio_context(bs); 1035 1036 trace_ssh_restart_coroutine(restart->co); 1037 aio_set_fd_handler(ctx, s->sock, false, NULL, NULL, NULL, NULL); 1038 1039 aio_co_wake(restart->co); 1040 } 1041 1042 /* A non-blocking call returned EAGAIN, so yield, ensuring the 1043 * handlers are set up so that we'll be rescheduled when there is an 1044 * interesting event on the socket. 1045 */ 1046 static coroutine_fn void co_yield(BDRVSSHState *s, BlockDriverState *bs) 1047 { 1048 int r; 1049 IOHandler *rd_handler = NULL, *wr_handler = NULL; 1050 BDRVSSHRestart restart = { 1051 .bs = bs, 1052 .co = qemu_coroutine_self() 1053 }; 1054 1055 r = ssh_get_poll_flags(s->session); 1056 1057 if (r & SSH_READ_PENDING) { 1058 rd_handler = restart_coroutine; 1059 } 1060 if (r & SSH_WRITE_PENDING) { 1061 wr_handler = restart_coroutine; 1062 } 1063 1064 trace_ssh_co_yield(s->sock, rd_handler, wr_handler); 1065 1066 aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock, 1067 false, rd_handler, wr_handler, NULL, &restart); 1068 qemu_coroutine_yield(); 1069 trace_ssh_co_yield_back(s->sock); 1070 } 1071 1072 static coroutine_fn int ssh_read(BDRVSSHState *s, BlockDriverState *bs, 1073 int64_t offset, size_t size, 1074 QEMUIOVector *qiov) 1075 { 1076 ssize_t r; 1077 size_t got; 1078 char *buf, *end_of_vec; 1079 struct iovec *i; 1080 1081 trace_ssh_read(offset, size); 1082 1083 trace_ssh_seek(offset); 1084 sftp_seek64(s->sftp_handle, offset); 1085 1086 /* This keeps track of the current iovec element ('i'), where we 1087 * will write to next ('buf'), and the end of the current iovec 1088 * ('end_of_vec'). 1089 */ 1090 i = &qiov->iov[0]; 1091 buf = i->iov_base; 1092 end_of_vec = i->iov_base + i->iov_len; 1093 1094 for (got = 0; got < size; ) { 1095 size_t request_read_size; 1096 again: 1097 /* 1098 * The size of SFTP packets is limited to 32K bytes, so limit 1099 * the amount of data requested to 16K, as libssh currently 1100 * does not handle multiple requests on its own. 1101 */ 1102 request_read_size = MIN(end_of_vec - buf, 16384); 1103 trace_ssh_read_buf(buf, end_of_vec - buf, request_read_size); 1104 r = sftp_read(s->sftp_handle, buf, request_read_size); 1105 trace_ssh_read_return(r, sftp_get_error(s->sftp)); 1106 1107 if (r == SSH_AGAIN) { 1108 co_yield(s, bs); 1109 goto again; 1110 } 1111 if (r == SSH_EOF || (r == 0 && sftp_get_error(s->sftp) == SSH_FX_EOF)) { 1112 /* EOF: Short read so pad the buffer with zeroes and return it. */ 1113 qemu_iovec_memset(qiov, got, 0, size - got); 1114 return 0; 1115 } 1116 if (r <= 0) { 1117 sftp_error_trace(s, "read"); 1118 return -EIO; 1119 } 1120 1121 got += r; 1122 buf += r; 1123 if (buf >= end_of_vec && got < size) { 1124 i++; 1125 buf = i->iov_base; 1126 end_of_vec = i->iov_base + i->iov_len; 1127 } 1128 } 1129 1130 return 0; 1131 } 1132 1133 static coroutine_fn int ssh_co_readv(BlockDriverState *bs, 1134 int64_t sector_num, 1135 int nb_sectors, QEMUIOVector *qiov) 1136 { 1137 BDRVSSHState *s = bs->opaque; 1138 int ret; 1139 1140 qemu_co_mutex_lock(&s->lock); 1141 ret = ssh_read(s, bs, sector_num * BDRV_SECTOR_SIZE, 1142 nb_sectors * BDRV_SECTOR_SIZE, qiov); 1143 qemu_co_mutex_unlock(&s->lock); 1144 1145 return ret; 1146 } 1147 1148 static int ssh_write(BDRVSSHState *s, BlockDriverState *bs, 1149 int64_t offset, size_t size, 1150 QEMUIOVector *qiov) 1151 { 1152 ssize_t r; 1153 size_t written; 1154 char *buf, *end_of_vec; 1155 struct iovec *i; 1156 1157 trace_ssh_write(offset, size); 1158 1159 trace_ssh_seek(offset); 1160 sftp_seek64(s->sftp_handle, offset); 1161 1162 /* This keeps track of the current iovec element ('i'), where we 1163 * will read from next ('buf'), and the end of the current iovec 1164 * ('end_of_vec'). 1165 */ 1166 i = &qiov->iov[0]; 1167 buf = i->iov_base; 1168 end_of_vec = i->iov_base + i->iov_len; 1169 1170 for (written = 0; written < size; ) { 1171 size_t request_write_size; 1172 again: 1173 /* 1174 * Avoid too large data packets, as libssh currently does not 1175 * handle multiple requests on its own. 1176 */ 1177 request_write_size = MIN(end_of_vec - buf, 131072); 1178 trace_ssh_write_buf(buf, end_of_vec - buf, request_write_size); 1179 r = sftp_write(s->sftp_handle, buf, request_write_size); 1180 trace_ssh_write_return(r, sftp_get_error(s->sftp)); 1181 1182 if (r == SSH_AGAIN) { 1183 co_yield(s, bs); 1184 goto again; 1185 } 1186 if (r < 0) { 1187 sftp_error_trace(s, "write"); 1188 return -EIO; 1189 } 1190 1191 written += r; 1192 buf += r; 1193 if (buf >= end_of_vec && written < size) { 1194 i++; 1195 buf = i->iov_base; 1196 end_of_vec = i->iov_base + i->iov_len; 1197 } 1198 1199 if (offset + written > s->attrs->size) { 1200 s->attrs->size = offset + written; 1201 } 1202 } 1203 1204 return 0; 1205 } 1206 1207 static coroutine_fn int ssh_co_writev(BlockDriverState *bs, 1208 int64_t sector_num, 1209 int nb_sectors, QEMUIOVector *qiov, 1210 int flags) 1211 { 1212 BDRVSSHState *s = bs->opaque; 1213 int ret; 1214 1215 assert(!flags); 1216 qemu_co_mutex_lock(&s->lock); 1217 ret = ssh_write(s, bs, sector_num * BDRV_SECTOR_SIZE, 1218 nb_sectors * BDRV_SECTOR_SIZE, qiov); 1219 qemu_co_mutex_unlock(&s->lock); 1220 1221 return ret; 1222 } 1223 1224 static void unsafe_flush_warning(BDRVSSHState *s, const char *what) 1225 { 1226 if (!s->unsafe_flush_warning) { 1227 warn_report("ssh server %s does not support fsync", 1228 s->inet->host); 1229 if (what) { 1230 error_report("to support fsync, you need %s", what); 1231 } 1232 s->unsafe_flush_warning = true; 1233 } 1234 } 1235 1236 #ifdef HAVE_LIBSSH_0_8 1237 1238 static coroutine_fn int ssh_flush(BDRVSSHState *s, BlockDriverState *bs) 1239 { 1240 int r; 1241 1242 trace_ssh_flush(); 1243 1244 if (!sftp_extension_supported(s->sftp, "fsync@openssh.com", "1")) { 1245 unsafe_flush_warning(s, "OpenSSH >= 6.3"); 1246 return 0; 1247 } 1248 again: 1249 r = sftp_fsync(s->sftp_handle); 1250 if (r == SSH_AGAIN) { 1251 co_yield(s, bs); 1252 goto again; 1253 } 1254 if (r < 0) { 1255 sftp_error_trace(s, "fsync"); 1256 return -EIO; 1257 } 1258 1259 return 0; 1260 } 1261 1262 static coroutine_fn int ssh_co_flush(BlockDriverState *bs) 1263 { 1264 BDRVSSHState *s = bs->opaque; 1265 int ret; 1266 1267 qemu_co_mutex_lock(&s->lock); 1268 ret = ssh_flush(s, bs); 1269 qemu_co_mutex_unlock(&s->lock); 1270 1271 return ret; 1272 } 1273 1274 #else /* !HAVE_LIBSSH_0_8 */ 1275 1276 static coroutine_fn int ssh_co_flush(BlockDriverState *bs) 1277 { 1278 BDRVSSHState *s = bs->opaque; 1279 1280 unsafe_flush_warning(s, "libssh >= 0.8.0"); 1281 return 0; 1282 } 1283 1284 #endif /* !HAVE_LIBSSH_0_8 */ 1285 1286 static int64_t ssh_getlength(BlockDriverState *bs) 1287 { 1288 BDRVSSHState *s = bs->opaque; 1289 int64_t length; 1290 1291 /* Note we cannot make a libssh call here. */ 1292 length = (int64_t) s->attrs->size; 1293 trace_ssh_getlength(length); 1294 1295 return length; 1296 } 1297 1298 static int coroutine_fn ssh_co_truncate(BlockDriverState *bs, int64_t offset, 1299 bool exact, PreallocMode prealloc, 1300 BdrvRequestFlags flags, Error **errp) 1301 { 1302 BDRVSSHState *s = bs->opaque; 1303 1304 if (prealloc != PREALLOC_MODE_OFF) { 1305 error_setg(errp, "Unsupported preallocation mode '%s'", 1306 PreallocMode_str(prealloc)); 1307 return -ENOTSUP; 1308 } 1309 1310 if (offset < s->attrs->size) { 1311 error_setg(errp, "ssh driver does not support shrinking files"); 1312 return -ENOTSUP; 1313 } 1314 1315 if (offset == s->attrs->size) { 1316 return 0; 1317 } 1318 1319 return ssh_grow_file(s, offset, errp); 1320 } 1321 1322 static void ssh_refresh_filename(BlockDriverState *bs) 1323 { 1324 BDRVSSHState *s = bs->opaque; 1325 const char *path, *host_key_check; 1326 int ret; 1327 1328 /* 1329 * None of these options can be represented in a plain "host:port" 1330 * format, so if any was given, we have to abort. 1331 */ 1332 if (s->inet->has_ipv4 || s->inet->has_ipv6 || s->inet->has_to || 1333 s->inet->has_numeric) 1334 { 1335 return; 1336 } 1337 1338 path = qdict_get_try_str(bs->full_open_options, "path"); 1339 assert(path); /* mandatory option */ 1340 1341 host_key_check = qdict_get_try_str(bs->full_open_options, "host_key_check"); 1342 1343 ret = snprintf(bs->exact_filename, sizeof(bs->exact_filename), 1344 "ssh://%s@%s:%s%s%s%s", 1345 s->user, s->inet->host, s->inet->port, path, 1346 host_key_check ? "?host_key_check=" : "", 1347 host_key_check ?: ""); 1348 if (ret >= sizeof(bs->exact_filename)) { 1349 /* An overflow makes the filename unusable, so do not report any */ 1350 bs->exact_filename[0] = '\0'; 1351 } 1352 } 1353 1354 static char *ssh_bdrv_dirname(BlockDriverState *bs, Error **errp) 1355 { 1356 if (qdict_haskey(bs->full_open_options, "host_key_check")) { 1357 /* 1358 * We cannot generate a simple prefix if we would have to 1359 * append a query string. 1360 */ 1361 error_setg(errp, 1362 "Cannot generate a base directory with host_key_check set"); 1363 return NULL; 1364 } 1365 1366 if (bs->exact_filename[0] == '\0') { 1367 error_setg(errp, "Cannot generate a base directory for this ssh node"); 1368 return NULL; 1369 } 1370 1371 return path_combine(bs->exact_filename, ""); 1372 } 1373 1374 static const char *const ssh_strong_runtime_opts[] = { 1375 "host", 1376 "port", 1377 "path", 1378 "user", 1379 "host_key_check", 1380 "server.", 1381 1382 NULL 1383 }; 1384 1385 static BlockDriver bdrv_ssh = { 1386 .format_name = "ssh", 1387 .protocol_name = "ssh", 1388 .instance_size = sizeof(BDRVSSHState), 1389 .bdrv_parse_filename = ssh_parse_filename, 1390 .bdrv_file_open = ssh_file_open, 1391 .bdrv_co_create = ssh_co_create, 1392 .bdrv_co_create_opts = ssh_co_create_opts, 1393 .bdrv_close = ssh_close, 1394 .bdrv_has_zero_init = ssh_has_zero_init, 1395 .bdrv_co_readv = ssh_co_readv, 1396 .bdrv_co_writev = ssh_co_writev, 1397 .bdrv_getlength = ssh_getlength, 1398 .bdrv_co_truncate = ssh_co_truncate, 1399 .bdrv_co_flush_to_disk = ssh_co_flush, 1400 .bdrv_refresh_filename = ssh_refresh_filename, 1401 .bdrv_dirname = ssh_bdrv_dirname, 1402 .create_opts = &ssh_create_opts, 1403 .strong_runtime_opts = ssh_strong_runtime_opts, 1404 }; 1405 1406 static void bdrv_ssh_init(void) 1407 { 1408 int r; 1409 1410 r = ssh_init(); 1411 if (r != 0) { 1412 fprintf(stderr, "libssh initialization failed, %d\n", r); 1413 exit(EXIT_FAILURE); 1414 } 1415 1416 #if TRACE_LIBSSH != 0 1417 ssh_set_log_level(TRACE_LIBSSH); 1418 #endif 1419 1420 bdrv_register(&bdrv_ssh); 1421 } 1422 1423 block_init(bdrv_ssh_init); 1424