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 UINT_MAX; 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 unsigned c0, c1; 380 while (*host_key_check == ':') 381 host_key_check++; 382 c0 = hex2decimal(host_key_check[0]); 383 c1 = hex2decimal(host_key_check[1]); 384 if (c0 > 0xf || c1 > 0xf) { 385 return 1; 386 } 387 c = c0 * 16 + c1; 388 if (c - *fingerprint != 0) 389 return c - *fingerprint; 390 fingerprint++; 391 len--; 392 host_key_check += 2; 393 } 394 return *host_key_check - '\0'; 395 } 396 397 static char *format_fingerprint(const unsigned char *fingerprint, size_t len) 398 { 399 static const char *hex = "0123456789abcdef"; 400 char *ret = g_new0(char, (len * 2) + 1); 401 for (size_t i = 0; i < len; i++) { 402 ret[i * 2] = hex[((fingerprint[i] >> 4) & 0xf)]; 403 ret[(i * 2) + 1] = hex[(fingerprint[i] & 0xf)]; 404 } 405 ret[len * 2] = '\0'; 406 return ret; 407 } 408 409 static int 410 check_host_key_hash(BDRVSSHState *s, const char *hash, 411 enum ssh_publickey_hash_type type, const char *typestr, 412 Error **errp) 413 { 414 int r; 415 ssh_key pubkey; 416 unsigned char *server_hash; 417 size_t server_hash_len; 418 const char *keytype; 419 420 r = ssh_get_server_publickey(s->session, &pubkey); 421 if (r != SSH_OK) { 422 session_error_setg(errp, s, "failed to read remote host key"); 423 return -EINVAL; 424 } 425 426 keytype = ssh_key_type_to_char(ssh_key_type(pubkey)); 427 428 r = ssh_get_publickey_hash(pubkey, type, &server_hash, &server_hash_len); 429 ssh_key_free(pubkey); 430 if (r != 0) { 431 session_error_setg(errp, s, 432 "failed reading the hash of the server SSH key"); 433 return -EINVAL; 434 } 435 436 r = compare_fingerprint(server_hash, server_hash_len, hash); 437 if (r != 0) { 438 g_autofree char *server_fp = format_fingerprint(server_hash, 439 server_hash_len); 440 error_setg(errp, "remote host %s key fingerprint '%s:%s' " 441 "does not match host_key_check '%s:%s'", 442 keytype, typestr, server_fp, typestr, hash); 443 ssh_clean_pubkey_hash(&server_hash); 444 return -EPERM; 445 } 446 ssh_clean_pubkey_hash(&server_hash); 447 448 return 0; 449 } 450 451 static int check_host_key(BDRVSSHState *s, SshHostKeyCheck *hkc, Error **errp) 452 { 453 SshHostKeyCheckMode mode; 454 455 if (hkc) { 456 mode = hkc->mode; 457 } else { 458 mode = SSH_HOST_KEY_CHECK_MODE_KNOWN_HOSTS; 459 } 460 461 switch (mode) { 462 case SSH_HOST_KEY_CHECK_MODE_NONE: 463 return 0; 464 case SSH_HOST_KEY_CHECK_MODE_HASH: 465 if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_MD5) { 466 return check_host_key_hash(s, hkc->u.hash.hash, 467 SSH_PUBLICKEY_HASH_MD5, "md5", 468 errp); 469 } else if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_SHA1) { 470 return check_host_key_hash(s, hkc->u.hash.hash, 471 SSH_PUBLICKEY_HASH_SHA1, "sha1", 472 errp); 473 } else if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_SHA256) { 474 return check_host_key_hash(s, hkc->u.hash.hash, 475 SSH_PUBLICKEY_HASH_SHA256, "sha256", 476 errp); 477 } 478 g_assert_not_reached(); 479 case SSH_HOST_KEY_CHECK_MODE_KNOWN_HOSTS: 480 return check_host_key_knownhosts(s, errp); 481 default: 482 g_assert_not_reached(); 483 } 484 485 return -EINVAL; 486 } 487 488 static int authenticate(BDRVSSHState *s, Error **errp) 489 { 490 int r, ret; 491 int method; 492 493 /* Try to authenticate with the "none" method. */ 494 r = ssh_userauth_none(s->session, NULL); 495 if (r == SSH_AUTH_ERROR) { 496 ret = -EPERM; 497 session_error_setg(errp, s, "failed to authenticate using none " 498 "authentication"); 499 goto out; 500 } else if (r == SSH_AUTH_SUCCESS) { 501 /* Authenticated! */ 502 ret = 0; 503 goto out; 504 } 505 506 method = ssh_userauth_list(s->session, NULL); 507 trace_ssh_auth_methods(method); 508 509 /* 510 * Try to authenticate with publickey, using the ssh-agent 511 * if available. 512 */ 513 if (method & SSH_AUTH_METHOD_PUBLICKEY) { 514 r = ssh_userauth_publickey_auto(s->session, NULL, NULL); 515 if (r == SSH_AUTH_ERROR) { 516 ret = -EINVAL; 517 session_error_setg(errp, s, "failed to authenticate using " 518 "publickey authentication"); 519 goto out; 520 } else if (r == SSH_AUTH_SUCCESS) { 521 /* Authenticated! */ 522 ret = 0; 523 goto out; 524 } 525 } 526 527 ret = -EPERM; 528 error_setg(errp, "failed to authenticate using publickey authentication " 529 "and the identities held by your ssh-agent"); 530 531 out: 532 return ret; 533 } 534 535 static QemuOptsList ssh_runtime_opts = { 536 .name = "ssh", 537 .head = QTAILQ_HEAD_INITIALIZER(ssh_runtime_opts.head), 538 .desc = { 539 { 540 .name = "host", 541 .type = QEMU_OPT_STRING, 542 .help = "Host to connect to", 543 }, 544 { 545 .name = "port", 546 .type = QEMU_OPT_NUMBER, 547 .help = "Port to connect to", 548 }, 549 { 550 .name = "host_key_check", 551 .type = QEMU_OPT_STRING, 552 .help = "Defines how and what to check the host key against", 553 }, 554 { /* end of list */ } 555 }, 556 }; 557 558 static bool ssh_process_legacy_options(QDict *output_opts, 559 QemuOpts *legacy_opts, 560 Error **errp) 561 { 562 const char *host = qemu_opt_get(legacy_opts, "host"); 563 const char *port = qemu_opt_get(legacy_opts, "port"); 564 const char *host_key_check = qemu_opt_get(legacy_opts, "host_key_check"); 565 566 if (!host && port) { 567 error_setg(errp, "port may not be used without host"); 568 return false; 569 } 570 571 if (host) { 572 qdict_put_str(output_opts, "server.host", host); 573 qdict_put_str(output_opts, "server.port", port ?: stringify(22)); 574 } 575 576 if (host_key_check) { 577 if (strcmp(host_key_check, "no") == 0) { 578 qdict_put_str(output_opts, "host-key-check.mode", "none"); 579 } else if (strncmp(host_key_check, "md5:", 4) == 0) { 580 qdict_put_str(output_opts, "host-key-check.mode", "hash"); 581 qdict_put_str(output_opts, "host-key-check.type", "md5"); 582 qdict_put_str(output_opts, "host-key-check.hash", 583 &host_key_check[4]); 584 } else if (strncmp(host_key_check, "sha1:", 5) == 0) { 585 qdict_put_str(output_opts, "host-key-check.mode", "hash"); 586 qdict_put_str(output_opts, "host-key-check.type", "sha1"); 587 qdict_put_str(output_opts, "host-key-check.hash", 588 &host_key_check[5]); 589 } else if (strncmp(host_key_check, "sha256:", 7) == 0) { 590 qdict_put_str(output_opts, "host-key-check.mode", "hash"); 591 qdict_put_str(output_opts, "host-key-check.type", "sha256"); 592 qdict_put_str(output_opts, "host-key-check.hash", 593 &host_key_check[7]); 594 } else if (strcmp(host_key_check, "yes") == 0) { 595 qdict_put_str(output_opts, "host-key-check.mode", "known_hosts"); 596 } else { 597 error_setg(errp, "unknown host_key_check setting (%s)", 598 host_key_check); 599 return false; 600 } 601 } 602 603 return true; 604 } 605 606 static BlockdevOptionsSsh *ssh_parse_options(QDict *options, Error **errp) 607 { 608 BlockdevOptionsSsh *result = NULL; 609 QemuOpts *opts = NULL; 610 const QDictEntry *e; 611 Visitor *v; 612 613 /* Translate legacy options */ 614 opts = qemu_opts_create(&ssh_runtime_opts, NULL, 0, &error_abort); 615 if (!qemu_opts_absorb_qdict(opts, options, errp)) { 616 goto fail; 617 } 618 619 if (!ssh_process_legacy_options(options, opts, errp)) { 620 goto fail; 621 } 622 623 /* Create the QAPI object */ 624 v = qobject_input_visitor_new_flat_confused(options, errp); 625 if (!v) { 626 goto fail; 627 } 628 629 visit_type_BlockdevOptionsSsh(v, NULL, &result, errp); 630 visit_free(v); 631 if (!result) { 632 goto fail; 633 } 634 635 /* Remove the processed options from the QDict (the visitor processes 636 * _all_ options in the QDict) */ 637 while ((e = qdict_first(options))) { 638 qdict_del(options, e->key); 639 } 640 641 fail: 642 qemu_opts_del(opts); 643 return result; 644 } 645 646 static int connect_to_ssh(BDRVSSHState *s, BlockdevOptionsSsh *opts, 647 int ssh_flags, int creat_mode, Error **errp) 648 { 649 int r, ret; 650 unsigned int port = 0; 651 int new_sock = -1; 652 653 if (opts->user) { 654 s->user = g_strdup(opts->user); 655 } else { 656 s->user = g_strdup(g_get_user_name()); 657 if (!s->user) { 658 error_setg_errno(errp, errno, "Can't get user name"); 659 ret = -errno; 660 goto err; 661 } 662 } 663 664 /* Pop the config into our state object, Exit if invalid */ 665 s->inet = opts->server; 666 opts->server = NULL; 667 668 if (qemu_strtoui(s->inet->port, NULL, 10, &port) < 0) { 669 error_setg(errp, "Use only numeric port value"); 670 ret = -EINVAL; 671 goto err; 672 } 673 674 /* Open the socket and connect. */ 675 new_sock = inet_connect_saddr(s->inet, errp); 676 if (new_sock < 0) { 677 ret = -EIO; 678 goto err; 679 } 680 681 /* 682 * Try to disable the Nagle algorithm on TCP sockets to reduce latency, 683 * but do not fail if it cannot be disabled. 684 */ 685 r = socket_set_nodelay(new_sock); 686 if (r < 0) { 687 warn_report("can't set TCP_NODELAY for the ssh server %s: %s", 688 s->inet->host, strerror(errno)); 689 } 690 691 /* Create SSH session. */ 692 s->session = ssh_new(); 693 if (!s->session) { 694 ret = -EINVAL; 695 session_error_setg(errp, s, "failed to initialize libssh session"); 696 goto err; 697 } 698 699 /* 700 * Make sure we are in blocking mode during the connection and 701 * authentication phases. 702 */ 703 ssh_set_blocking(s->session, 1); 704 705 r = ssh_options_set(s->session, SSH_OPTIONS_USER, s->user); 706 if (r < 0) { 707 ret = -EINVAL; 708 session_error_setg(errp, s, 709 "failed to set the user in the libssh session"); 710 goto err; 711 } 712 713 r = ssh_options_set(s->session, SSH_OPTIONS_HOST, s->inet->host); 714 if (r < 0) { 715 ret = -EINVAL; 716 session_error_setg(errp, s, 717 "failed to set the host in the libssh session"); 718 goto err; 719 } 720 721 if (port > 0) { 722 r = ssh_options_set(s->session, SSH_OPTIONS_PORT, &port); 723 if (r < 0) { 724 ret = -EINVAL; 725 session_error_setg(errp, s, 726 "failed to set the port in the libssh session"); 727 goto err; 728 } 729 } 730 731 r = ssh_options_set(s->session, SSH_OPTIONS_COMPRESSION, "none"); 732 if (r < 0) { 733 ret = -EINVAL; 734 session_error_setg(errp, s, 735 "failed to disable the compression in the libssh " 736 "session"); 737 goto err; 738 } 739 740 /* Read ~/.ssh/config. */ 741 r = ssh_options_parse_config(s->session, NULL); 742 if (r < 0) { 743 ret = -EINVAL; 744 session_error_setg(errp, s, "failed to parse ~/.ssh/config"); 745 goto err; 746 } 747 748 r = ssh_options_set(s->session, SSH_OPTIONS_FD, &new_sock); 749 if (r < 0) { 750 ret = -EINVAL; 751 session_error_setg(errp, s, 752 "failed to set the socket in the libssh session"); 753 goto err; 754 } 755 /* libssh took ownership of the socket. */ 756 s->sock = new_sock; 757 new_sock = -1; 758 759 /* Connect. */ 760 r = ssh_connect(s->session); 761 if (r != SSH_OK) { 762 ret = -EINVAL; 763 session_error_setg(errp, s, "failed to establish SSH session"); 764 goto err; 765 } 766 767 /* Check the remote host's key against known_hosts. */ 768 ret = check_host_key(s, opts->host_key_check, errp); 769 if (ret < 0) { 770 goto err; 771 } 772 773 /* Authenticate. */ 774 ret = authenticate(s, errp); 775 if (ret < 0) { 776 goto err; 777 } 778 779 /* Start SFTP. */ 780 s->sftp = sftp_new(s->session); 781 if (!s->sftp) { 782 session_error_setg(errp, s, "failed to create sftp handle"); 783 ret = -EINVAL; 784 goto err; 785 } 786 787 r = sftp_init(s->sftp); 788 if (r < 0) { 789 sftp_error_setg(errp, s, "failed to initialize sftp handle"); 790 ret = -EINVAL; 791 goto err; 792 } 793 794 /* Open the remote file. */ 795 trace_ssh_connect_to_ssh(opts->path, ssh_flags, creat_mode); 796 s->sftp_handle = sftp_open(s->sftp, opts->path, ssh_flags, creat_mode); 797 if (!s->sftp_handle) { 798 sftp_error_setg(errp, s, "failed to open remote file '%s'", 799 opts->path); 800 ret = -EINVAL; 801 goto err; 802 } 803 804 /* Make sure the SFTP file is handled in blocking mode. */ 805 sftp_file_set_blocking(s->sftp_handle); 806 807 s->attrs = sftp_fstat(s->sftp_handle); 808 if (!s->attrs) { 809 sftp_error_setg(errp, s, "failed to read file attributes"); 810 return -EINVAL; 811 } 812 813 return 0; 814 815 err: 816 if (s->attrs) { 817 sftp_attributes_free(s->attrs); 818 } 819 s->attrs = NULL; 820 if (s->sftp_handle) { 821 sftp_close(s->sftp_handle); 822 } 823 s->sftp_handle = NULL; 824 if (s->sftp) { 825 sftp_free(s->sftp); 826 } 827 s->sftp = NULL; 828 if (s->session) { 829 ssh_disconnect(s->session); 830 ssh_free(s->session); 831 } 832 s->session = NULL; 833 s->sock = -1; 834 if (new_sock >= 0) { 835 close(new_sock); 836 } 837 838 return ret; 839 } 840 841 static int ssh_open(BlockDriverState *bs, QDict *options, int bdrv_flags, 842 Error **errp) 843 { 844 BDRVSSHState *s = bs->opaque; 845 BlockdevOptionsSsh *opts; 846 int ret; 847 int ssh_flags; 848 849 ssh_state_init(s); 850 851 ssh_flags = 0; 852 if (bdrv_flags & BDRV_O_RDWR) { 853 ssh_flags |= O_RDWR; 854 } else { 855 ssh_flags |= O_RDONLY; 856 } 857 858 opts = ssh_parse_options(options, errp); 859 if (opts == NULL) { 860 return -EINVAL; 861 } 862 863 /* Start up SSH. */ 864 ret = connect_to_ssh(s, opts, ssh_flags, 0, errp); 865 if (ret < 0) { 866 goto err; 867 } 868 869 /* Go non-blocking. */ 870 ssh_set_blocking(s->session, 0); 871 872 if (s->attrs->type == SSH_FILEXFER_TYPE_REGULAR) { 873 bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE; 874 } 875 876 qapi_free_BlockdevOptionsSsh(opts); 877 878 return 0; 879 880 err: 881 qapi_free_BlockdevOptionsSsh(opts); 882 883 return ret; 884 } 885 886 /* Note: This is a blocking operation */ 887 static int ssh_grow_file(BDRVSSHState *s, int64_t offset, Error **errp) 888 { 889 ssize_t ret; 890 char c[1] = { '\0' }; 891 int was_blocking = ssh_is_blocking(s->session); 892 893 /* offset must be strictly greater than the current size so we do 894 * not overwrite anything */ 895 assert(offset > 0 && offset > s->attrs->size); 896 897 ssh_set_blocking(s->session, 1); 898 899 sftp_seek64(s->sftp_handle, offset - 1); 900 ret = sftp_write(s->sftp_handle, c, 1); 901 902 ssh_set_blocking(s->session, was_blocking); 903 904 if (ret < 0) { 905 sftp_error_setg(errp, s, "Failed to grow file"); 906 return -EIO; 907 } 908 909 s->attrs->size = offset; 910 return 0; 911 } 912 913 static QemuOptsList ssh_create_opts = { 914 .name = "ssh-create-opts", 915 .head = QTAILQ_HEAD_INITIALIZER(ssh_create_opts.head), 916 .desc = { 917 { 918 .name = BLOCK_OPT_SIZE, 919 .type = QEMU_OPT_SIZE, 920 .help = "Virtual disk size" 921 }, 922 { /* end of list */ } 923 } 924 }; 925 926 static int ssh_co_create(BlockdevCreateOptions *options, Error **errp) 927 { 928 BlockdevCreateOptionsSsh *opts = &options->u.ssh; 929 BDRVSSHState s; 930 int ret; 931 932 assert(options->driver == BLOCKDEV_DRIVER_SSH); 933 934 ssh_state_init(&s); 935 936 ret = connect_to_ssh(&s, opts->location, 937 O_RDWR | O_CREAT | O_TRUNC, 938 0644, errp); 939 if (ret < 0) { 940 goto fail; 941 } 942 943 if (opts->size > 0) { 944 ret = ssh_grow_file(&s, opts->size, errp); 945 if (ret < 0) { 946 goto fail; 947 } 948 } 949 950 ret = 0; 951 fail: 952 ssh_state_free(&s); 953 return ret; 954 } 955 956 static int coroutine_fn ssh_co_create_opts(BlockDriver *drv, 957 const char *filename, 958 QemuOpts *opts, 959 Error **errp) 960 { 961 BlockdevCreateOptions *create_options; 962 BlockdevCreateOptionsSsh *ssh_opts; 963 int ret; 964 QDict *uri_options = NULL; 965 966 create_options = g_new0(BlockdevCreateOptions, 1); 967 create_options->driver = BLOCKDEV_DRIVER_SSH; 968 ssh_opts = &create_options->u.ssh; 969 970 /* Get desired file size. */ 971 ssh_opts->size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0), 972 BDRV_SECTOR_SIZE); 973 trace_ssh_co_create_opts(ssh_opts->size); 974 975 uri_options = qdict_new(); 976 ret = parse_uri(filename, uri_options, errp); 977 if (ret < 0) { 978 goto out; 979 } 980 981 ssh_opts->location = ssh_parse_options(uri_options, errp); 982 if (ssh_opts->location == NULL) { 983 ret = -EINVAL; 984 goto out; 985 } 986 987 ret = ssh_co_create(create_options, errp); 988 989 out: 990 qobject_unref(uri_options); 991 qapi_free_BlockdevCreateOptions(create_options); 992 return ret; 993 } 994 995 static void ssh_close(BlockDriverState *bs) 996 { 997 BDRVSSHState *s = bs->opaque; 998 999 ssh_state_free(s); 1000 } 1001 1002 static int ssh_has_zero_init(BlockDriverState *bs) 1003 { 1004 BDRVSSHState *s = bs->opaque; 1005 /* Assume false, unless we can positively prove it's true. */ 1006 int has_zero_init = 0; 1007 1008 if (s->attrs->type == SSH_FILEXFER_TYPE_REGULAR) { 1009 has_zero_init = 1; 1010 } 1011 1012 return has_zero_init; 1013 } 1014 1015 typedef struct BDRVSSHRestart { 1016 BlockDriverState *bs; 1017 Coroutine *co; 1018 } BDRVSSHRestart; 1019 1020 static void restart_coroutine(void *opaque) 1021 { 1022 BDRVSSHRestart *restart = opaque; 1023 BlockDriverState *bs = restart->bs; 1024 BDRVSSHState *s = bs->opaque; 1025 AioContext *ctx = bdrv_get_aio_context(bs); 1026 1027 trace_ssh_restart_coroutine(restart->co); 1028 aio_set_fd_handler(ctx, s->sock, NULL, NULL, NULL, NULL, NULL); 1029 1030 aio_co_wake(restart->co); 1031 } 1032 1033 /* A non-blocking call returned EAGAIN, so yield, ensuring the 1034 * handlers are set up so that we'll be rescheduled when there is an 1035 * interesting event on the socket. 1036 */ 1037 static coroutine_fn void co_yield(BDRVSSHState *s, BlockDriverState *bs) 1038 { 1039 int r; 1040 IOHandler *rd_handler = NULL, *wr_handler = NULL; 1041 BDRVSSHRestart restart = { 1042 .bs = bs, 1043 .co = qemu_coroutine_self() 1044 }; 1045 1046 r = ssh_get_poll_flags(s->session); 1047 1048 if (r & SSH_READ_PENDING) { 1049 rd_handler = restart_coroutine; 1050 } 1051 if (r & SSH_WRITE_PENDING) { 1052 wr_handler = restart_coroutine; 1053 } 1054 1055 trace_ssh_co_yield(s->sock, rd_handler, wr_handler); 1056 1057 aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock, 1058 rd_handler, wr_handler, NULL, NULL, &restart); 1059 qemu_coroutine_yield(); 1060 trace_ssh_co_yield_back(s->sock); 1061 } 1062 1063 static coroutine_fn int ssh_read(BDRVSSHState *s, BlockDriverState *bs, 1064 int64_t offset, size_t size, 1065 QEMUIOVector *qiov) 1066 { 1067 ssize_t r; 1068 size_t got; 1069 char *buf, *end_of_vec; 1070 struct iovec *i; 1071 1072 trace_ssh_read(offset, size); 1073 1074 trace_ssh_seek(offset); 1075 sftp_seek64(s->sftp_handle, offset); 1076 1077 /* This keeps track of the current iovec element ('i'), where we 1078 * will write to next ('buf'), and the end of the current iovec 1079 * ('end_of_vec'). 1080 */ 1081 i = &qiov->iov[0]; 1082 buf = i->iov_base; 1083 end_of_vec = i->iov_base + i->iov_len; 1084 1085 for (got = 0; got < size; ) { 1086 size_t request_read_size; 1087 again: 1088 /* 1089 * The size of SFTP packets is limited to 32K bytes, so limit 1090 * the amount of data requested to 16K, as libssh currently 1091 * does not handle multiple requests on its own. 1092 */ 1093 request_read_size = MIN(end_of_vec - buf, 16384); 1094 trace_ssh_read_buf(buf, end_of_vec - buf, request_read_size); 1095 r = sftp_read(s->sftp_handle, buf, request_read_size); 1096 trace_ssh_read_return(r, sftp_get_error(s->sftp)); 1097 1098 if (r == SSH_AGAIN) { 1099 co_yield(s, bs); 1100 goto again; 1101 } 1102 if (r == SSH_EOF || (r == 0 && sftp_get_error(s->sftp) == SSH_FX_EOF)) { 1103 /* EOF: Short read so pad the buffer with zeroes and return it. */ 1104 qemu_iovec_memset(qiov, got, 0, size - got); 1105 return 0; 1106 } 1107 if (r <= 0) { 1108 sftp_error_trace(s, "read"); 1109 return -EIO; 1110 } 1111 1112 got += r; 1113 buf += r; 1114 if (buf >= end_of_vec && got < size) { 1115 i++; 1116 buf = i->iov_base; 1117 end_of_vec = i->iov_base + i->iov_len; 1118 } 1119 } 1120 1121 return 0; 1122 } 1123 1124 static coroutine_fn int ssh_co_readv(BlockDriverState *bs, 1125 int64_t sector_num, 1126 int nb_sectors, QEMUIOVector *qiov) 1127 { 1128 BDRVSSHState *s = bs->opaque; 1129 int ret; 1130 1131 qemu_co_mutex_lock(&s->lock); 1132 ret = ssh_read(s, bs, sector_num * BDRV_SECTOR_SIZE, 1133 nb_sectors * BDRV_SECTOR_SIZE, qiov); 1134 qemu_co_mutex_unlock(&s->lock); 1135 1136 return ret; 1137 } 1138 1139 static coroutine_fn int ssh_write(BDRVSSHState *s, BlockDriverState *bs, 1140 int64_t offset, size_t size, 1141 QEMUIOVector *qiov) 1142 { 1143 ssize_t r; 1144 size_t written; 1145 char *buf, *end_of_vec; 1146 struct iovec *i; 1147 1148 trace_ssh_write(offset, size); 1149 1150 trace_ssh_seek(offset); 1151 sftp_seek64(s->sftp_handle, offset); 1152 1153 /* This keeps track of the current iovec element ('i'), where we 1154 * will read from next ('buf'), and the end of the current iovec 1155 * ('end_of_vec'). 1156 */ 1157 i = &qiov->iov[0]; 1158 buf = i->iov_base; 1159 end_of_vec = i->iov_base + i->iov_len; 1160 1161 for (written = 0; written < size; ) { 1162 size_t request_write_size; 1163 again: 1164 /* 1165 * Avoid too large data packets, as libssh currently does not 1166 * handle multiple requests on its own. 1167 */ 1168 request_write_size = MIN(end_of_vec - buf, 131072); 1169 trace_ssh_write_buf(buf, end_of_vec - buf, request_write_size); 1170 r = sftp_write(s->sftp_handle, buf, request_write_size); 1171 trace_ssh_write_return(r, sftp_get_error(s->sftp)); 1172 1173 if (r == SSH_AGAIN) { 1174 co_yield(s, bs); 1175 goto again; 1176 } 1177 if (r < 0) { 1178 sftp_error_trace(s, "write"); 1179 return -EIO; 1180 } 1181 1182 written += r; 1183 buf += r; 1184 if (buf >= end_of_vec && written < size) { 1185 i++; 1186 buf = i->iov_base; 1187 end_of_vec = i->iov_base + i->iov_len; 1188 } 1189 1190 if (offset + written > s->attrs->size) { 1191 s->attrs->size = offset + written; 1192 } 1193 } 1194 1195 return 0; 1196 } 1197 1198 static coroutine_fn int ssh_co_writev(BlockDriverState *bs, 1199 int64_t sector_num, 1200 int nb_sectors, QEMUIOVector *qiov, 1201 int flags) 1202 { 1203 BDRVSSHState *s = bs->opaque; 1204 int ret; 1205 1206 qemu_co_mutex_lock(&s->lock); 1207 ret = ssh_write(s, bs, sector_num * BDRV_SECTOR_SIZE, 1208 nb_sectors * BDRV_SECTOR_SIZE, qiov); 1209 qemu_co_mutex_unlock(&s->lock); 1210 1211 return ret; 1212 } 1213 1214 static void unsafe_flush_warning(BDRVSSHState *s, const char *what) 1215 { 1216 if (!s->unsafe_flush_warning) { 1217 warn_report("ssh server %s does not support fsync", 1218 s->inet->host); 1219 if (what) { 1220 error_report("to support fsync, you need %s", what); 1221 } 1222 s->unsafe_flush_warning = true; 1223 } 1224 } 1225 1226 static coroutine_fn int ssh_flush(BDRVSSHState *s, BlockDriverState *bs) 1227 { 1228 int r; 1229 1230 trace_ssh_flush(); 1231 1232 if (!sftp_extension_supported(s->sftp, "fsync@openssh.com", "1")) { 1233 unsafe_flush_warning(s, "OpenSSH >= 6.3"); 1234 return 0; 1235 } 1236 again: 1237 r = sftp_fsync(s->sftp_handle); 1238 if (r == SSH_AGAIN) { 1239 co_yield(s, bs); 1240 goto again; 1241 } 1242 if (r < 0) { 1243 sftp_error_trace(s, "fsync"); 1244 return -EIO; 1245 } 1246 1247 return 0; 1248 } 1249 1250 static coroutine_fn int ssh_co_flush(BlockDriverState *bs) 1251 { 1252 BDRVSSHState *s = bs->opaque; 1253 int ret; 1254 1255 qemu_co_mutex_lock(&s->lock); 1256 ret = ssh_flush(s, bs); 1257 qemu_co_mutex_unlock(&s->lock); 1258 1259 return ret; 1260 } 1261 1262 static int64_t coroutine_fn ssh_co_getlength(BlockDriverState *bs) 1263 { 1264 BDRVSSHState *s = bs->opaque; 1265 int64_t length; 1266 1267 /* Note we cannot make a libssh call here. */ 1268 length = (int64_t) s->attrs->size; 1269 trace_ssh_getlength(length); 1270 1271 return length; 1272 } 1273 1274 static int coroutine_fn ssh_co_truncate(BlockDriverState *bs, int64_t offset, 1275 bool exact, PreallocMode prealloc, 1276 BdrvRequestFlags flags, Error **errp) 1277 { 1278 BDRVSSHState *s = bs->opaque; 1279 1280 if (prealloc != PREALLOC_MODE_OFF) { 1281 error_setg(errp, "Unsupported preallocation mode '%s'", 1282 PreallocMode_str(prealloc)); 1283 return -ENOTSUP; 1284 } 1285 1286 if (offset < s->attrs->size) { 1287 error_setg(errp, "ssh driver does not support shrinking files"); 1288 return -ENOTSUP; 1289 } 1290 1291 if (offset == s->attrs->size) { 1292 return 0; 1293 } 1294 1295 return ssh_grow_file(s, offset, errp); 1296 } 1297 1298 static void ssh_refresh_filename(BlockDriverState *bs) 1299 { 1300 BDRVSSHState *s = bs->opaque; 1301 const char *path, *host_key_check; 1302 int ret; 1303 1304 /* 1305 * None of these options can be represented in a plain "host:port" 1306 * format, so if any was given, we have to abort. 1307 */ 1308 if (s->inet->has_ipv4 || s->inet->has_ipv6 || s->inet->has_to || 1309 s->inet->has_numeric) 1310 { 1311 return; 1312 } 1313 1314 path = qdict_get_try_str(bs->full_open_options, "path"); 1315 assert(path); /* mandatory option */ 1316 1317 host_key_check = qdict_get_try_str(bs->full_open_options, "host_key_check"); 1318 1319 ret = snprintf(bs->exact_filename, sizeof(bs->exact_filename), 1320 "ssh://%s@%s:%s%s%s%s", 1321 s->user, s->inet->host, s->inet->port, path, 1322 host_key_check ? "?host_key_check=" : "", 1323 host_key_check ?: ""); 1324 if (ret >= sizeof(bs->exact_filename)) { 1325 /* An overflow makes the filename unusable, so do not report any */ 1326 bs->exact_filename[0] = '\0'; 1327 } 1328 } 1329 1330 static char *ssh_bdrv_dirname(BlockDriverState *bs, Error **errp) 1331 { 1332 if (qdict_haskey(bs->full_open_options, "host_key_check")) { 1333 /* 1334 * We cannot generate a simple prefix if we would have to 1335 * append a query string. 1336 */ 1337 error_setg(errp, 1338 "Cannot generate a base directory with host_key_check set"); 1339 return NULL; 1340 } 1341 1342 if (bs->exact_filename[0] == '\0') { 1343 error_setg(errp, "Cannot generate a base directory for this ssh node"); 1344 return NULL; 1345 } 1346 1347 return path_combine(bs->exact_filename, ""); 1348 } 1349 1350 static const char *const ssh_strong_runtime_opts[] = { 1351 "host", 1352 "port", 1353 "path", 1354 "user", 1355 "host_key_check", 1356 "server.", 1357 1358 NULL 1359 }; 1360 1361 static BlockDriver bdrv_ssh = { 1362 .format_name = "ssh", 1363 .protocol_name = "ssh", 1364 .instance_size = sizeof(BDRVSSHState), 1365 .bdrv_parse_filename = ssh_parse_filename, 1366 .bdrv_open = ssh_open, 1367 .bdrv_co_create = ssh_co_create, 1368 .bdrv_co_create_opts = ssh_co_create_opts, 1369 .bdrv_close = ssh_close, 1370 .bdrv_has_zero_init = ssh_has_zero_init, 1371 .bdrv_co_readv = ssh_co_readv, 1372 .bdrv_co_writev = ssh_co_writev, 1373 .bdrv_co_getlength = ssh_co_getlength, 1374 .bdrv_co_truncate = ssh_co_truncate, 1375 .bdrv_co_flush_to_disk = ssh_co_flush, 1376 .bdrv_refresh_filename = ssh_refresh_filename, 1377 .bdrv_dirname = ssh_bdrv_dirname, 1378 .create_opts = &ssh_create_opts, 1379 .strong_runtime_opts = ssh_strong_runtime_opts, 1380 }; 1381 1382 static void bdrv_ssh_init(void) 1383 { 1384 int r; 1385 1386 r = ssh_init(); 1387 if (r != 0) { 1388 fprintf(stderr, "libssh initialization failed, %d\n", r); 1389 exit(EXIT_FAILURE); 1390 } 1391 1392 #if TRACE_LIBSSH != 0 1393 ssh_set_log_level(TRACE_LIBSSH); 1394 #endif 1395 1396 bdrv_register(&bdrv_ssh); 1397 } 1398 1399 block_init(bdrv_ssh_init); 1400