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