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-io.h" 31 #include "block/block_int.h" 32 #include "block/qdict.h" 33 #include "qapi/error.h" 34 #include "qemu/error-report.h" 35 #include "qemu/module.h" 36 #include "qemu/option.h" 37 #include "qemu/ctype.h" 38 #include "qemu/cutils.h" 39 #include "qemu/sockets.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 G_GNUC_PRINTF(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 G_GNUC_PRINTF(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 g_autoptr(GUri) uri = g_uri_parse(filename, G_URI_FLAGS_NONE, NULL); 184 const char *uri_host, *uri_path, *uri_user, *uri_query; 185 char *port_str; 186 int port; 187 g_autoptr(GError) gerror = NULL; 188 char *qp_name, *qp_value; 189 GUriParamsIter qp; 190 191 if (!uri) { 192 return -EINVAL; 193 } 194 195 if (g_strcmp0(g_uri_get_scheme(uri), "ssh") != 0) { 196 error_setg(errp, "URI scheme must be 'ssh'"); 197 return -EINVAL; 198 } 199 200 uri_host = g_uri_get_host(uri); 201 if (!uri_host || g_str_equal(uri_host, "")) { 202 error_setg(errp, "missing hostname in URI"); 203 return -EINVAL; 204 } 205 206 uri_path = g_uri_get_path(uri); 207 if (!uri_path || g_str_equal(uri_path, "")) { 208 error_setg(errp, "missing remote path in URI"); 209 return -EINVAL; 210 } 211 212 uri_user = g_uri_get_user(uri); 213 if (uri_user && !g_str_equal(uri_user, "")) { 214 qdict_put_str(options, "user", uri_user); 215 } 216 217 qdict_put_str(options, "server.host", uri_host); 218 219 port = g_uri_get_port(uri); 220 port_str = g_strdup_printf("%d", port > 0 ? 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 uri_query = g_uri_get_query(uri); 227 if (uri_query) { 228 g_uri_params_iter_init(&qp, uri_query, -1, "&", G_URI_PARAMS_NONE); 229 while (g_uri_params_iter_next(&qp, &qp_name, &qp_value, &gerror)) { 230 if (!qp_name || !qp_value || gerror) { 231 warn_report("Failed to parse SSH URI parameters '%s'", 232 uri_query); 233 break; 234 } 235 /* 236 * Pick out the query parameters that we understand, and ignore 237 * (or rather warn about) the rest. 238 */ 239 if (g_str_equal(qp_name, "host_key_check")) { 240 qdict_put_str(options, "host_key_check", qp_value); 241 } else { 242 warn_report("Unsupported parameter '%s' in URI", qp_name); 243 } 244 } 245 } 246 247 return 0; 248 } 249 250 static bool ssh_has_filename_options_conflict(QDict *options, Error **errp) 251 { 252 const QDictEntry *qe; 253 254 for (qe = qdict_first(options); qe; qe = qdict_next(options, qe)) { 255 if (!strcmp(qe->key, "host") || 256 !strcmp(qe->key, "port") || 257 !strcmp(qe->key, "path") || 258 !strcmp(qe->key, "user") || 259 !strcmp(qe->key, "host_key_check") || 260 strstart(qe->key, "server.", NULL)) 261 { 262 error_setg(errp, "Option '%s' cannot be used with a file name", 263 qe->key); 264 return true; 265 } 266 } 267 268 return false; 269 } 270 271 static void ssh_parse_filename(const char *filename, QDict *options, 272 Error **errp) 273 { 274 if (ssh_has_filename_options_conflict(options, errp)) { 275 return; 276 } 277 278 parse_uri(filename, options, errp); 279 } 280 281 static int check_host_key_knownhosts(BDRVSSHState *s, Error **errp) 282 { 283 int ret; 284 enum ssh_known_hosts_e state; 285 int r; 286 ssh_key pubkey; 287 enum ssh_keytypes_e pubkey_type; 288 unsigned char *server_hash = NULL; 289 size_t server_hash_len; 290 char *fingerprint = NULL; 291 292 state = ssh_session_is_known_server(s->session); 293 trace_ssh_server_status(state); 294 295 switch (state) { 296 case SSH_KNOWN_HOSTS_OK: 297 /* OK */ 298 trace_ssh_check_host_key_knownhosts(); 299 break; 300 case SSH_KNOWN_HOSTS_CHANGED: 301 ret = -EINVAL; 302 r = ssh_get_server_publickey(s->session, &pubkey); 303 if (r == 0) { 304 r = ssh_get_publickey_hash(pubkey, SSH_PUBLICKEY_HASH_SHA256, 305 &server_hash, &server_hash_len); 306 pubkey_type = ssh_key_type(pubkey); 307 ssh_key_free(pubkey); 308 } 309 if (r == 0) { 310 fingerprint = ssh_get_fingerprint_hash(SSH_PUBLICKEY_HASH_SHA256, 311 server_hash, 312 server_hash_len); 313 ssh_clean_pubkey_hash(&server_hash); 314 } 315 if (fingerprint) { 316 error_setg(errp, 317 "host key (%s key with fingerprint %s) does not match " 318 "the one in known_hosts; this may be a possible attack", 319 ssh_key_type_to_char(pubkey_type), fingerprint); 320 ssh_string_free_char(fingerprint); 321 } else { 322 error_setg(errp, 323 "host key does not match the one in known_hosts; this " 324 "may be a possible attack"); 325 } 326 goto out; 327 case SSH_KNOWN_HOSTS_OTHER: 328 ret = -EINVAL; 329 error_setg(errp, 330 "host key for this server not found, another type exists"); 331 goto out; 332 case SSH_KNOWN_HOSTS_UNKNOWN: 333 ret = -EINVAL; 334 error_setg(errp, "no host key was found in known_hosts"); 335 goto out; 336 case SSH_KNOWN_HOSTS_NOT_FOUND: 337 ret = -ENOENT; 338 error_setg(errp, "known_hosts file not found"); 339 goto out; 340 case SSH_KNOWN_HOSTS_ERROR: 341 ret = -EINVAL; 342 error_setg(errp, "error while checking the host"); 343 goto out; 344 default: 345 ret = -EINVAL; 346 error_setg(errp, "error while checking for known server (%d)", state); 347 goto out; 348 } 349 350 /* known_hosts checking successful. */ 351 ret = 0; 352 353 out: 354 return ret; 355 } 356 357 static unsigned hex2decimal(char ch) 358 { 359 if (ch >= '0' && ch <= '9') { 360 return (ch - '0'); 361 } else if (ch >= 'a' && ch <= 'f') { 362 return 10 + (ch - 'a'); 363 } else if (ch >= 'A' && ch <= 'F') { 364 return 10 + (ch - 'A'); 365 } 366 367 return -1; 368 } 369 370 /* Compare the binary fingerprint (hash of host key) with the 371 * host_key_check parameter. 372 */ 373 static int compare_fingerprint(const unsigned char *fingerprint, size_t len, 374 const char *host_key_check) 375 { 376 unsigned c; 377 378 while (len > 0) { 379 while (*host_key_check == ':') 380 host_key_check++; 381 if (!qemu_isxdigit(host_key_check[0]) || 382 !qemu_isxdigit(host_key_check[1])) 383 return 1; 384 c = hex2decimal(host_key_check[0]) * 16 + 385 hex2decimal(host_key_check[1]); 386 if (c - *fingerprint != 0) 387 return c - *fingerprint; 388 fingerprint++; 389 len--; 390 host_key_check += 2; 391 } 392 return *host_key_check - '\0'; 393 } 394 395 static char *format_fingerprint(const unsigned char *fingerprint, size_t len) 396 { 397 static const char *hex = "0123456789abcdef"; 398 char *ret = g_new0(char, (len * 2) + 1); 399 for (size_t i = 0; i < len; i++) { 400 ret[i * 2] = hex[((fingerprint[i] >> 4) & 0xf)]; 401 ret[(i * 2) + 1] = hex[(fingerprint[i] & 0xf)]; 402 } 403 ret[len * 2] = '\0'; 404 return ret; 405 } 406 407 static int 408 check_host_key_hash(BDRVSSHState *s, const char *hash, 409 enum ssh_publickey_hash_type type, const char *typestr, 410 Error **errp) 411 { 412 int r; 413 ssh_key pubkey; 414 unsigned char *server_hash; 415 size_t server_hash_len; 416 const char *keytype; 417 418 r = ssh_get_server_publickey(s->session, &pubkey); 419 if (r != SSH_OK) { 420 session_error_setg(errp, s, "failed to read remote host key"); 421 return -EINVAL; 422 } 423 424 keytype = ssh_key_type_to_char(ssh_key_type(pubkey)); 425 426 r = ssh_get_publickey_hash(pubkey, type, &server_hash, &server_hash_len); 427 ssh_key_free(pubkey); 428 if (r != 0) { 429 session_error_setg(errp, s, 430 "failed reading the hash of the server SSH key"); 431 return -EINVAL; 432 } 433 434 r = compare_fingerprint(server_hash, server_hash_len, hash); 435 if (r != 0) { 436 g_autofree char *server_fp = format_fingerprint(server_hash, 437 server_hash_len); 438 error_setg(errp, "remote host %s key fingerprint '%s:%s' " 439 "does not match host_key_check '%s:%s'", 440 keytype, typestr, server_fp, typestr, hash); 441 ssh_clean_pubkey_hash(&server_hash); 442 return -EPERM; 443 } 444 ssh_clean_pubkey_hash(&server_hash); 445 446 return 0; 447 } 448 449 static int check_host_key(BDRVSSHState *s, SshHostKeyCheck *hkc, Error **errp) 450 { 451 SshHostKeyCheckMode mode; 452 453 if (hkc) { 454 mode = hkc->mode; 455 } else { 456 mode = SSH_HOST_KEY_CHECK_MODE_KNOWN_HOSTS; 457 } 458 459 switch (mode) { 460 case SSH_HOST_KEY_CHECK_MODE_NONE: 461 return 0; 462 case SSH_HOST_KEY_CHECK_MODE_HASH: 463 if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_MD5) { 464 return check_host_key_hash(s, hkc->u.hash.hash, 465 SSH_PUBLICKEY_HASH_MD5, "md5", 466 errp); 467 } else if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_SHA1) { 468 return check_host_key_hash(s, hkc->u.hash.hash, 469 SSH_PUBLICKEY_HASH_SHA1, "sha1", 470 errp); 471 } else if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_SHA256) { 472 return check_host_key_hash(s, hkc->u.hash.hash, 473 SSH_PUBLICKEY_HASH_SHA256, "sha256", 474 errp); 475 } 476 g_assert_not_reached(); 477 case SSH_HOST_KEY_CHECK_MODE_KNOWN_HOSTS: 478 return check_host_key_knownhosts(s, errp); 479 default: 480 g_assert_not_reached(); 481 } 482 483 return -EINVAL; 484 } 485 486 static int authenticate(BDRVSSHState *s, Error **errp) 487 { 488 int r, ret; 489 int method; 490 491 /* Try to authenticate with the "none" method. */ 492 r = ssh_userauth_none(s->session, NULL); 493 if (r == SSH_AUTH_ERROR) { 494 ret = -EPERM; 495 session_error_setg(errp, s, "failed to authenticate using none " 496 "authentication"); 497 goto out; 498 } else if (r == SSH_AUTH_SUCCESS) { 499 /* Authenticated! */ 500 ret = 0; 501 goto out; 502 } 503 504 method = ssh_userauth_list(s->session, NULL); 505 trace_ssh_auth_methods(method); 506 507 /* 508 * Try to authenticate with publickey, using the ssh-agent 509 * if available. 510 */ 511 if (method & SSH_AUTH_METHOD_PUBLICKEY) { 512 r = ssh_userauth_publickey_auto(s->session, NULL, NULL); 513 if (r == SSH_AUTH_ERROR) { 514 ret = -EINVAL; 515 session_error_setg(errp, s, "failed to authenticate using " 516 "publickey authentication"); 517 goto out; 518 } else if (r == SSH_AUTH_SUCCESS) { 519 /* Authenticated! */ 520 ret = 0; 521 goto out; 522 } 523 } 524 525 ret = -EPERM; 526 error_setg(errp, "failed to authenticate using publickey authentication " 527 "and the identities held by your ssh-agent"); 528 529 out: 530 return ret; 531 } 532 533 static QemuOptsList ssh_runtime_opts = { 534 .name = "ssh", 535 .head = QTAILQ_HEAD_INITIALIZER(ssh_runtime_opts.head), 536 .desc = { 537 { 538 .name = "host", 539 .type = QEMU_OPT_STRING, 540 .help = "Host to connect to", 541 }, 542 { 543 .name = "port", 544 .type = QEMU_OPT_NUMBER, 545 .help = "Port to connect to", 546 }, 547 { 548 .name = "host_key_check", 549 .type = QEMU_OPT_STRING, 550 .help = "Defines how and what to check the host key against", 551 }, 552 { /* end of list */ } 553 }, 554 }; 555 556 static bool ssh_process_legacy_options(QDict *output_opts, 557 QemuOpts *legacy_opts, 558 Error **errp) 559 { 560 const char *host = qemu_opt_get(legacy_opts, "host"); 561 const char *port = qemu_opt_get(legacy_opts, "port"); 562 const char *host_key_check = qemu_opt_get(legacy_opts, "host_key_check"); 563 564 if (!host && port) { 565 error_setg(errp, "port may not be used without host"); 566 return false; 567 } 568 569 if (host) { 570 qdict_put_str(output_opts, "server.host", host); 571 qdict_put_str(output_opts, "server.port", port ?: stringify(22)); 572 } 573 574 if (host_key_check) { 575 if (strcmp(host_key_check, "no") == 0) { 576 qdict_put_str(output_opts, "host-key-check.mode", "none"); 577 } else if (strncmp(host_key_check, "md5:", 4) == 0) { 578 qdict_put_str(output_opts, "host-key-check.mode", "hash"); 579 qdict_put_str(output_opts, "host-key-check.type", "md5"); 580 qdict_put_str(output_opts, "host-key-check.hash", 581 &host_key_check[4]); 582 } else if (strncmp(host_key_check, "sha1:", 5) == 0) { 583 qdict_put_str(output_opts, "host-key-check.mode", "hash"); 584 qdict_put_str(output_opts, "host-key-check.type", "sha1"); 585 qdict_put_str(output_opts, "host-key-check.hash", 586 &host_key_check[5]); 587 } else if (strncmp(host_key_check, "sha256:", 7) == 0) { 588 qdict_put_str(output_opts, "host-key-check.mode", "hash"); 589 qdict_put_str(output_opts, "host-key-check.type", "sha256"); 590 qdict_put_str(output_opts, "host-key-check.hash", 591 &host_key_check[7]); 592 } else if (strcmp(host_key_check, "yes") == 0) { 593 qdict_put_str(output_opts, "host-key-check.mode", "known_hosts"); 594 } else { 595 error_setg(errp, "unknown host_key_check setting (%s)", 596 host_key_check); 597 return false; 598 } 599 } 600 601 return true; 602 } 603 604 static BlockdevOptionsSsh *ssh_parse_options(QDict *options, Error **errp) 605 { 606 BlockdevOptionsSsh *result = NULL; 607 QemuOpts *opts = NULL; 608 const QDictEntry *e; 609 Visitor *v; 610 611 /* Translate legacy options */ 612 opts = qemu_opts_create(&ssh_runtime_opts, NULL, 0, &error_abort); 613 if (!qemu_opts_absorb_qdict(opts, options, errp)) { 614 goto fail; 615 } 616 617 if (!ssh_process_legacy_options(options, opts, errp)) { 618 goto fail; 619 } 620 621 /* Create the QAPI object */ 622 v = qobject_input_visitor_new_flat_confused(options, errp); 623 if (!v) { 624 goto fail; 625 } 626 627 visit_type_BlockdevOptionsSsh(v, NULL, &result, errp); 628 visit_free(v); 629 if (!result) { 630 goto fail; 631 } 632 633 /* Remove the processed options from the QDict (the visitor processes 634 * _all_ options in the QDict) */ 635 while ((e = qdict_first(options))) { 636 qdict_del(options, e->key); 637 } 638 639 fail: 640 qemu_opts_del(opts); 641 return result; 642 } 643 644 static int connect_to_ssh(BDRVSSHState *s, BlockdevOptionsSsh *opts, 645 int ssh_flags, int creat_mode, Error **errp) 646 { 647 int r, ret; 648 unsigned int port = 0; 649 int new_sock = -1; 650 651 if (opts->user) { 652 s->user = g_strdup(opts->user); 653 } else { 654 s->user = g_strdup(g_get_user_name()); 655 if (!s->user) { 656 error_setg_errno(errp, errno, "Can't get user name"); 657 ret = -errno; 658 goto err; 659 } 660 } 661 662 /* Pop the config into our state object, Exit if invalid */ 663 s->inet = opts->server; 664 opts->server = NULL; 665 666 if (qemu_strtoui(s->inet->port, NULL, 10, &port) < 0) { 667 error_setg(errp, "Use only numeric port value"); 668 ret = -EINVAL; 669 goto err; 670 } 671 672 /* Open the socket and connect. */ 673 new_sock = inet_connect_saddr(s->inet, errp); 674 if (new_sock < 0) { 675 ret = -EIO; 676 goto err; 677 } 678 679 /* 680 * Try to disable the Nagle algorithm on TCP sockets to reduce latency, 681 * but do not fail if it cannot be disabled. 682 */ 683 r = socket_set_nodelay(new_sock); 684 if (r < 0) { 685 warn_report("can't set TCP_NODELAY for the ssh server %s: %s", 686 s->inet->host, strerror(errno)); 687 } 688 689 /* Create SSH session. */ 690 s->session = ssh_new(); 691 if (!s->session) { 692 ret = -EINVAL; 693 session_error_setg(errp, s, "failed to initialize libssh session"); 694 goto err; 695 } 696 697 /* 698 * Make sure we are in blocking mode during the connection and 699 * authentication phases. 700 */ 701 ssh_set_blocking(s->session, 1); 702 703 r = ssh_options_set(s->session, SSH_OPTIONS_USER, s->user); 704 if (r < 0) { 705 ret = -EINVAL; 706 session_error_setg(errp, s, 707 "failed to set the user in the libssh session"); 708 goto err; 709 } 710 711 r = ssh_options_set(s->session, SSH_OPTIONS_HOST, s->inet->host); 712 if (r < 0) { 713 ret = -EINVAL; 714 session_error_setg(errp, s, 715 "failed to set the host in the libssh session"); 716 goto err; 717 } 718 719 if (port > 0) { 720 r = ssh_options_set(s->session, SSH_OPTIONS_PORT, &port); 721 if (r < 0) { 722 ret = -EINVAL; 723 session_error_setg(errp, s, 724 "failed to set the port in the libssh session"); 725 goto err; 726 } 727 } 728 729 r = ssh_options_set(s->session, SSH_OPTIONS_COMPRESSION, "none"); 730 if (r < 0) { 731 ret = -EINVAL; 732 session_error_setg(errp, s, 733 "failed to disable the compression in the libssh " 734 "session"); 735 goto err; 736 } 737 738 /* Read ~/.ssh/config. */ 739 r = ssh_options_parse_config(s->session, NULL); 740 if (r < 0) { 741 ret = -EINVAL; 742 session_error_setg(errp, s, "failed to parse ~/.ssh/config"); 743 goto err; 744 } 745 746 r = ssh_options_set(s->session, SSH_OPTIONS_FD, &new_sock); 747 if (r < 0) { 748 ret = -EINVAL; 749 session_error_setg(errp, s, 750 "failed to set the socket in the libssh session"); 751 goto err; 752 } 753 /* libssh took ownership of the socket. */ 754 s->sock = new_sock; 755 new_sock = -1; 756 757 /* Connect. */ 758 r = ssh_connect(s->session); 759 if (r != SSH_OK) { 760 ret = -EINVAL; 761 session_error_setg(errp, s, "failed to establish SSH session"); 762 goto err; 763 } 764 765 /* Check the remote host's key against known_hosts. */ 766 ret = check_host_key(s, opts->host_key_check, errp); 767 if (ret < 0) { 768 goto err; 769 } 770 771 /* Authenticate. */ 772 ret = authenticate(s, errp); 773 if (ret < 0) { 774 goto err; 775 } 776 777 /* Start SFTP. */ 778 s->sftp = sftp_new(s->session); 779 if (!s->sftp) { 780 session_error_setg(errp, s, "failed to create sftp handle"); 781 ret = -EINVAL; 782 goto err; 783 } 784 785 r = sftp_init(s->sftp); 786 if (r < 0) { 787 sftp_error_setg(errp, s, "failed to initialize sftp handle"); 788 ret = -EINVAL; 789 goto err; 790 } 791 792 /* Open the remote file. */ 793 trace_ssh_connect_to_ssh(opts->path, ssh_flags, creat_mode); 794 s->sftp_handle = sftp_open(s->sftp, opts->path, ssh_flags, creat_mode); 795 if (!s->sftp_handle) { 796 sftp_error_setg(errp, s, "failed to open remote file '%s'", 797 opts->path); 798 ret = -EINVAL; 799 goto err; 800 } 801 802 /* Make sure the SFTP file is handled in blocking mode. */ 803 sftp_file_set_blocking(s->sftp_handle); 804 805 s->attrs = sftp_fstat(s->sftp_handle); 806 if (!s->attrs) { 807 sftp_error_setg(errp, s, "failed to read file attributes"); 808 return -EINVAL; 809 } 810 811 return 0; 812 813 err: 814 if (s->attrs) { 815 sftp_attributes_free(s->attrs); 816 } 817 s->attrs = NULL; 818 if (s->sftp_handle) { 819 sftp_close(s->sftp_handle); 820 } 821 s->sftp_handle = NULL; 822 if (s->sftp) { 823 sftp_free(s->sftp); 824 } 825 s->sftp = NULL; 826 if (s->session) { 827 ssh_disconnect(s->session); 828 ssh_free(s->session); 829 } 830 s->session = NULL; 831 s->sock = -1; 832 if (new_sock >= 0) { 833 close(new_sock); 834 } 835 836 return ret; 837 } 838 839 static int ssh_open(BlockDriverState *bs, QDict *options, int bdrv_flags, 840 Error **errp) 841 { 842 BDRVSSHState *s = bs->opaque; 843 BlockdevOptionsSsh *opts; 844 int ret; 845 int ssh_flags; 846 847 ssh_state_init(s); 848 849 ssh_flags = 0; 850 if (bdrv_flags & BDRV_O_RDWR) { 851 ssh_flags |= O_RDWR; 852 } else { 853 ssh_flags |= O_RDONLY; 854 } 855 856 opts = ssh_parse_options(options, errp); 857 if (opts == NULL) { 858 return -EINVAL; 859 } 860 861 /* Start up SSH. */ 862 ret = connect_to_ssh(s, opts, ssh_flags, 0, errp); 863 if (ret < 0) { 864 goto err; 865 } 866 867 /* Go non-blocking. */ 868 ssh_set_blocking(s->session, 0); 869 870 if (s->attrs->type == SSH_FILEXFER_TYPE_REGULAR) { 871 bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE; 872 } 873 874 qapi_free_BlockdevOptionsSsh(opts); 875 876 return 0; 877 878 err: 879 qapi_free_BlockdevOptionsSsh(opts); 880 881 return ret; 882 } 883 884 /* Note: This is a blocking operation */ 885 static int ssh_grow_file(BDRVSSHState *s, int64_t offset, Error **errp) 886 { 887 ssize_t ret; 888 char c[1] = { '\0' }; 889 int was_blocking = ssh_is_blocking(s->session); 890 891 /* offset must be strictly greater than the current size so we do 892 * not overwrite anything */ 893 assert(offset > 0 && offset > s->attrs->size); 894 895 ssh_set_blocking(s->session, 1); 896 897 sftp_seek64(s->sftp_handle, offset - 1); 898 ret = sftp_write(s->sftp_handle, c, 1); 899 900 ssh_set_blocking(s->session, was_blocking); 901 902 if (ret < 0) { 903 sftp_error_setg(errp, s, "Failed to grow file"); 904 return -EIO; 905 } 906 907 s->attrs->size = offset; 908 return 0; 909 } 910 911 static QemuOptsList ssh_create_opts = { 912 .name = "ssh-create-opts", 913 .head = QTAILQ_HEAD_INITIALIZER(ssh_create_opts.head), 914 .desc = { 915 { 916 .name = BLOCK_OPT_SIZE, 917 .type = QEMU_OPT_SIZE, 918 .help = "Virtual disk size" 919 }, 920 { /* end of list */ } 921 } 922 }; 923 924 static int ssh_co_create(BlockdevCreateOptions *options, Error **errp) 925 { 926 BlockdevCreateOptionsSsh *opts = &options->u.ssh; 927 BDRVSSHState s; 928 int ret; 929 930 assert(options->driver == BLOCKDEV_DRIVER_SSH); 931 932 ssh_state_init(&s); 933 934 ret = connect_to_ssh(&s, opts->location, 935 O_RDWR | O_CREAT | O_TRUNC, 936 0644, errp); 937 if (ret < 0) { 938 goto fail; 939 } 940 941 if (opts->size > 0) { 942 ret = ssh_grow_file(&s, opts->size, errp); 943 if (ret < 0) { 944 goto fail; 945 } 946 } 947 948 ret = 0; 949 fail: 950 ssh_state_free(&s); 951 return ret; 952 } 953 954 static int coroutine_fn ssh_co_create_opts(BlockDriver *drv, 955 const char *filename, 956 QemuOpts *opts, 957 Error **errp) 958 { 959 BlockdevCreateOptions *create_options; 960 BlockdevCreateOptionsSsh *ssh_opts; 961 int ret; 962 QDict *uri_options = NULL; 963 964 create_options = g_new0(BlockdevCreateOptions, 1); 965 create_options->driver = BLOCKDEV_DRIVER_SSH; 966 ssh_opts = &create_options->u.ssh; 967 968 /* Get desired file size. */ 969 ssh_opts->size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0), 970 BDRV_SECTOR_SIZE); 971 trace_ssh_co_create_opts(ssh_opts->size); 972 973 uri_options = qdict_new(); 974 ret = parse_uri(filename, uri_options, errp); 975 if (ret < 0) { 976 goto out; 977 } 978 979 ssh_opts->location = ssh_parse_options(uri_options, errp); 980 if (ssh_opts->location == NULL) { 981 ret = -EINVAL; 982 goto out; 983 } 984 985 ret = ssh_co_create(create_options, errp); 986 987 out: 988 qobject_unref(uri_options); 989 qapi_free_BlockdevCreateOptions(create_options); 990 return ret; 991 } 992 993 static void ssh_close(BlockDriverState *bs) 994 { 995 BDRVSSHState *s = bs->opaque; 996 997 ssh_state_free(s); 998 } 999 1000 static int ssh_has_zero_init(BlockDriverState *bs) 1001 { 1002 BDRVSSHState *s = bs->opaque; 1003 /* Assume false, unless we can positively prove it's true. */ 1004 int has_zero_init = 0; 1005 1006 if (s->attrs->type == SSH_FILEXFER_TYPE_REGULAR) { 1007 has_zero_init = 1; 1008 } 1009 1010 return has_zero_init; 1011 } 1012 1013 typedef struct BDRVSSHRestart { 1014 BlockDriverState *bs; 1015 Coroutine *co; 1016 } BDRVSSHRestart; 1017 1018 static void restart_coroutine(void *opaque) 1019 { 1020 BDRVSSHRestart *restart = opaque; 1021 BlockDriverState *bs = restart->bs; 1022 BDRVSSHState *s = bs->opaque; 1023 AioContext *ctx = bdrv_get_aio_context(bs); 1024 1025 trace_ssh_restart_coroutine(restart->co); 1026 aio_set_fd_handler(ctx, s->sock, NULL, NULL, NULL, NULL, NULL); 1027 1028 aio_co_wake(restart->co); 1029 } 1030 1031 /* A non-blocking call returned EAGAIN, so yield, ensuring the 1032 * handlers are set up so that we'll be rescheduled when there is an 1033 * interesting event on the socket. 1034 */ 1035 static coroutine_fn void co_yield(BDRVSSHState *s, BlockDriverState *bs) 1036 { 1037 int r; 1038 IOHandler *rd_handler = NULL, *wr_handler = NULL; 1039 BDRVSSHRestart restart = { 1040 .bs = bs, 1041 .co = qemu_coroutine_self() 1042 }; 1043 1044 r = ssh_get_poll_flags(s->session); 1045 1046 if (r & SSH_READ_PENDING) { 1047 rd_handler = restart_coroutine; 1048 } 1049 if (r & SSH_WRITE_PENDING) { 1050 wr_handler = restart_coroutine; 1051 } 1052 1053 trace_ssh_co_yield(s->sock, rd_handler, wr_handler); 1054 1055 aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock, 1056 rd_handler, wr_handler, NULL, NULL, &restart); 1057 qemu_coroutine_yield(); 1058 trace_ssh_co_yield_back(s->sock); 1059 } 1060 1061 static coroutine_fn int ssh_read(BDRVSSHState *s, BlockDriverState *bs, 1062 int64_t offset, size_t size, 1063 QEMUIOVector *qiov) 1064 { 1065 ssize_t r; 1066 size_t got; 1067 char *buf, *end_of_vec; 1068 struct iovec *i; 1069 1070 trace_ssh_read(offset, size); 1071 1072 trace_ssh_seek(offset); 1073 sftp_seek64(s->sftp_handle, offset); 1074 1075 /* This keeps track of the current iovec element ('i'), where we 1076 * will write to next ('buf'), and the end of the current iovec 1077 * ('end_of_vec'). 1078 */ 1079 i = &qiov->iov[0]; 1080 buf = i->iov_base; 1081 end_of_vec = i->iov_base + i->iov_len; 1082 1083 for (got = 0; got < size; ) { 1084 size_t request_read_size; 1085 again: 1086 /* 1087 * The size of SFTP packets is limited to 32K bytes, so limit 1088 * the amount of data requested to 16K, as libssh currently 1089 * does not handle multiple requests on its own. 1090 */ 1091 request_read_size = MIN(end_of_vec - buf, 16384); 1092 trace_ssh_read_buf(buf, end_of_vec - buf, request_read_size); 1093 r = sftp_read(s->sftp_handle, buf, request_read_size); 1094 trace_ssh_read_return(r, sftp_get_error(s->sftp)); 1095 1096 if (r == SSH_AGAIN) { 1097 co_yield(s, bs); 1098 goto again; 1099 } 1100 if (r == SSH_EOF || (r == 0 && sftp_get_error(s->sftp) == SSH_FX_EOF)) { 1101 /* EOF: Short read so pad the buffer with zeroes and return it. */ 1102 qemu_iovec_memset(qiov, got, 0, size - got); 1103 return 0; 1104 } 1105 if (r <= 0) { 1106 sftp_error_trace(s, "read"); 1107 return -EIO; 1108 } 1109 1110 got += r; 1111 buf += r; 1112 if (buf >= end_of_vec && got < size) { 1113 i++; 1114 buf = i->iov_base; 1115 end_of_vec = i->iov_base + i->iov_len; 1116 } 1117 } 1118 1119 return 0; 1120 } 1121 1122 static coroutine_fn int ssh_co_readv(BlockDriverState *bs, 1123 int64_t sector_num, 1124 int nb_sectors, QEMUIOVector *qiov) 1125 { 1126 BDRVSSHState *s = bs->opaque; 1127 int ret; 1128 1129 qemu_co_mutex_lock(&s->lock); 1130 ret = ssh_read(s, bs, sector_num * BDRV_SECTOR_SIZE, 1131 nb_sectors * BDRV_SECTOR_SIZE, qiov); 1132 qemu_co_mutex_unlock(&s->lock); 1133 1134 return ret; 1135 } 1136 1137 static coroutine_fn int ssh_write(BDRVSSHState *s, BlockDriverState *bs, 1138 int64_t offset, size_t size, 1139 QEMUIOVector *qiov) 1140 { 1141 ssize_t r; 1142 size_t written; 1143 char *buf, *end_of_vec; 1144 struct iovec *i; 1145 1146 trace_ssh_write(offset, size); 1147 1148 trace_ssh_seek(offset); 1149 sftp_seek64(s->sftp_handle, offset); 1150 1151 /* This keeps track of the current iovec element ('i'), where we 1152 * will read from next ('buf'), and the end of the current iovec 1153 * ('end_of_vec'). 1154 */ 1155 i = &qiov->iov[0]; 1156 buf = i->iov_base; 1157 end_of_vec = i->iov_base + i->iov_len; 1158 1159 for (written = 0; written < size; ) { 1160 size_t request_write_size; 1161 again: 1162 /* 1163 * Avoid too large data packets, as libssh currently does not 1164 * handle multiple requests on its own. 1165 */ 1166 request_write_size = MIN(end_of_vec - buf, 131072); 1167 trace_ssh_write_buf(buf, end_of_vec - buf, request_write_size); 1168 r = sftp_write(s->sftp_handle, buf, request_write_size); 1169 trace_ssh_write_return(r, sftp_get_error(s->sftp)); 1170 1171 if (r == SSH_AGAIN) { 1172 co_yield(s, bs); 1173 goto again; 1174 } 1175 if (r < 0) { 1176 sftp_error_trace(s, "write"); 1177 return -EIO; 1178 } 1179 1180 written += r; 1181 buf += r; 1182 if (buf >= end_of_vec && written < size) { 1183 i++; 1184 buf = i->iov_base; 1185 end_of_vec = i->iov_base + i->iov_len; 1186 } 1187 1188 if (offset + written > s->attrs->size) { 1189 s->attrs->size = offset + written; 1190 } 1191 } 1192 1193 return 0; 1194 } 1195 1196 static coroutine_fn int ssh_co_writev(BlockDriverState *bs, 1197 int64_t sector_num, 1198 int nb_sectors, QEMUIOVector *qiov, 1199 int flags) 1200 { 1201 BDRVSSHState *s = bs->opaque; 1202 int ret; 1203 1204 qemu_co_mutex_lock(&s->lock); 1205 ret = ssh_write(s, bs, sector_num * BDRV_SECTOR_SIZE, 1206 nb_sectors * BDRV_SECTOR_SIZE, qiov); 1207 qemu_co_mutex_unlock(&s->lock); 1208 1209 return ret; 1210 } 1211 1212 static void unsafe_flush_warning(BDRVSSHState *s, const char *what) 1213 { 1214 if (!s->unsafe_flush_warning) { 1215 warn_report("ssh server %s does not support fsync", 1216 s->inet->host); 1217 if (what) { 1218 error_report("to support fsync, you need %s", what); 1219 } 1220 s->unsafe_flush_warning = true; 1221 } 1222 } 1223 1224 static coroutine_fn int ssh_flush(BDRVSSHState *s, BlockDriverState *bs) 1225 { 1226 int r; 1227 1228 trace_ssh_flush(); 1229 1230 if (!sftp_extension_supported(s->sftp, "fsync@openssh.com", "1")) { 1231 unsafe_flush_warning(s, "OpenSSH >= 6.3"); 1232 return 0; 1233 } 1234 again: 1235 r = sftp_fsync(s->sftp_handle); 1236 if (r == SSH_AGAIN) { 1237 co_yield(s, bs); 1238 goto again; 1239 } 1240 if (r < 0) { 1241 sftp_error_trace(s, "fsync"); 1242 return -EIO; 1243 } 1244 1245 return 0; 1246 } 1247 1248 static coroutine_fn int ssh_co_flush(BlockDriverState *bs) 1249 { 1250 BDRVSSHState *s = bs->opaque; 1251 int ret; 1252 1253 qemu_co_mutex_lock(&s->lock); 1254 ret = ssh_flush(s, bs); 1255 qemu_co_mutex_unlock(&s->lock); 1256 1257 return ret; 1258 } 1259 1260 static int64_t coroutine_fn ssh_co_getlength(BlockDriverState *bs) 1261 { 1262 BDRVSSHState *s = bs->opaque; 1263 int64_t length; 1264 1265 /* Note we cannot make a libssh call here. */ 1266 length = (int64_t) s->attrs->size; 1267 trace_ssh_getlength(length); 1268 1269 return length; 1270 } 1271 1272 static int coroutine_fn ssh_co_truncate(BlockDriverState *bs, int64_t offset, 1273 bool exact, PreallocMode prealloc, 1274 BdrvRequestFlags flags, Error **errp) 1275 { 1276 BDRVSSHState *s = bs->opaque; 1277 1278 if (prealloc != PREALLOC_MODE_OFF) { 1279 error_setg(errp, "Unsupported preallocation mode '%s'", 1280 PreallocMode_str(prealloc)); 1281 return -ENOTSUP; 1282 } 1283 1284 if (offset < s->attrs->size) { 1285 error_setg(errp, "ssh driver does not support shrinking files"); 1286 return -ENOTSUP; 1287 } 1288 1289 if (offset == s->attrs->size) { 1290 return 0; 1291 } 1292 1293 return ssh_grow_file(s, offset, errp); 1294 } 1295 1296 static void ssh_refresh_filename(BlockDriverState *bs) 1297 { 1298 BDRVSSHState *s = bs->opaque; 1299 const char *path, *host_key_check; 1300 int ret; 1301 1302 /* 1303 * None of these options can be represented in a plain "host:port" 1304 * format, so if any was given, we have to abort. 1305 */ 1306 if (s->inet->has_ipv4 || s->inet->has_ipv6 || s->inet->has_to || 1307 s->inet->has_numeric) 1308 { 1309 return; 1310 } 1311 1312 path = qdict_get_try_str(bs->full_open_options, "path"); 1313 assert(path); /* mandatory option */ 1314 1315 host_key_check = qdict_get_try_str(bs->full_open_options, "host_key_check"); 1316 1317 ret = snprintf(bs->exact_filename, sizeof(bs->exact_filename), 1318 "ssh://%s@%s:%s%s%s%s", 1319 s->user, s->inet->host, s->inet->port, path, 1320 host_key_check ? "?host_key_check=" : "", 1321 host_key_check ?: ""); 1322 if (ret >= sizeof(bs->exact_filename)) { 1323 /* An overflow makes the filename unusable, so do not report any */ 1324 bs->exact_filename[0] = '\0'; 1325 } 1326 } 1327 1328 static char *ssh_bdrv_dirname(BlockDriverState *bs, Error **errp) 1329 { 1330 if (qdict_haskey(bs->full_open_options, "host_key_check")) { 1331 /* 1332 * We cannot generate a simple prefix if we would have to 1333 * append a query string. 1334 */ 1335 error_setg(errp, 1336 "Cannot generate a base directory with host_key_check set"); 1337 return NULL; 1338 } 1339 1340 if (bs->exact_filename[0] == '\0') { 1341 error_setg(errp, "Cannot generate a base directory for this ssh node"); 1342 return NULL; 1343 } 1344 1345 return path_combine(bs->exact_filename, ""); 1346 } 1347 1348 static const char *const ssh_strong_runtime_opts[] = { 1349 "host", 1350 "port", 1351 "path", 1352 "user", 1353 "host_key_check", 1354 "server.", 1355 1356 NULL 1357 }; 1358 1359 static BlockDriver bdrv_ssh = { 1360 .format_name = "ssh", 1361 .protocol_name = "ssh", 1362 .instance_size = sizeof(BDRVSSHState), 1363 .bdrv_parse_filename = ssh_parse_filename, 1364 .bdrv_open = ssh_open, 1365 .bdrv_co_create = ssh_co_create, 1366 .bdrv_co_create_opts = ssh_co_create_opts, 1367 .bdrv_close = ssh_close, 1368 .bdrv_has_zero_init = ssh_has_zero_init, 1369 .bdrv_co_readv = ssh_co_readv, 1370 .bdrv_co_writev = ssh_co_writev, 1371 .bdrv_co_getlength = ssh_co_getlength, 1372 .bdrv_co_truncate = ssh_co_truncate, 1373 .bdrv_co_flush_to_disk = ssh_co_flush, 1374 .bdrv_refresh_filename = ssh_refresh_filename, 1375 .bdrv_dirname = ssh_bdrv_dirname, 1376 .create_opts = &ssh_create_opts, 1377 .strong_runtime_opts = ssh_strong_runtime_opts, 1378 }; 1379 1380 static void bdrv_ssh_init(void) 1381 { 1382 int r; 1383 1384 r = ssh_init(); 1385 if (r != 0) { 1386 fprintf(stderr, "libssh initialization failed, %d\n", r); 1387 exit(EXIT_FAILURE); 1388 } 1389 1390 #if TRACE_LIBSSH != 0 1391 ssh_set_log_level(TRACE_LIBSSH); 1392 #endif 1393 1394 bdrv_register(&bdrv_ssh); 1395 } 1396 1397 block_init(bdrv_ssh_init); 1398