1 /* 2 * Secure Shell (ssh) backend for QEMU. 3 * 4 * Copyright (C) 2013 Red Hat Inc., Richard W.M. Jones <rjones@redhat.com> 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a copy 7 * of this software and associated documentation files (the "Software"), to deal 8 * in the Software without restriction, including without limitation the rights 9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 10 * copies of the Software, and to permit persons to whom the Software is 11 * furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 22 * THE SOFTWARE. 23 */ 24 25 #include "qemu/osdep.h" 26 27 #include <libssh/libssh.h> 28 #include <libssh/sftp.h> 29 30 #include "block/block_int.h" 31 #include "block/qdict.h" 32 #include "qapi/error.h" 33 #include "qemu/error-report.h" 34 #include "qemu/module.h" 35 #include "qemu/option.h" 36 #include "qemu/ctype.h" 37 #include "qemu/cutils.h" 38 #include "qemu/sockets.h" 39 #include "qemu/uri.h" 40 #include "qapi/qapi-visit-sockets.h" 41 #include "qapi/qapi-visit-block-core.h" 42 #include "qapi/qmp/qdict.h" 43 #include "qapi/qmp/qstring.h" 44 #include "qapi/qobject-input-visitor.h" 45 #include "qapi/qobject-output-visitor.h" 46 #include "trace.h" 47 48 /* 49 * TRACE_LIBSSH=<level> enables tracing in libssh itself. 50 * The meaning of <level> is described here: 51 * http://api.libssh.org/master/group__libssh__log.html 52 */ 53 #define TRACE_LIBSSH 0 /* see: SSH_LOG_* */ 54 55 typedef struct BDRVSSHState { 56 /* Coroutine. */ 57 CoMutex lock; 58 59 /* SSH connection. */ 60 int sock; /* socket */ 61 ssh_session session; /* ssh session */ 62 sftp_session sftp; /* sftp session */ 63 sftp_file sftp_handle; /* sftp remote file handle */ 64 65 /* 66 * File attributes at open. We try to keep the .size field 67 * updated if it changes (eg by writing at the end of the file). 68 */ 69 sftp_attributes attrs; 70 71 InetSocketAddress *inet; 72 73 /* Used to warn if 'flush' is not supported. */ 74 bool unsafe_flush_warning; 75 76 /* 77 * Store the user name for ssh_refresh_filename() because the 78 * default depends on the system you are on -- therefore, when we 79 * generate a filename, it should always contain the user name we 80 * are actually using. 81 */ 82 char *user; 83 } BDRVSSHState; 84 85 static void ssh_state_init(BDRVSSHState *s) 86 { 87 memset(s, 0, sizeof *s); 88 s->sock = -1; 89 qemu_co_mutex_init(&s->lock); 90 } 91 92 static void ssh_state_free(BDRVSSHState *s) 93 { 94 g_free(s->user); 95 96 if (s->attrs) { 97 sftp_attributes_free(s->attrs); 98 } 99 if (s->sftp_handle) { 100 sftp_close(s->sftp_handle); 101 } 102 if (s->sftp) { 103 sftp_free(s->sftp); 104 } 105 if (s->session) { 106 ssh_disconnect(s->session); 107 ssh_free(s->session); /* This frees s->sock */ 108 } 109 } 110 111 static void 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 URI *uri = NULL; 184 QueryParams *qp; 185 char *port_str; 186 int i; 187 188 uri = uri_parse(filename); 189 if (!uri) { 190 return -EINVAL; 191 } 192 193 if (g_strcmp0(uri->scheme, "ssh") != 0) { 194 error_setg(errp, "URI scheme must be 'ssh'"); 195 goto err; 196 } 197 198 if (!uri->server || strcmp(uri->server, "") == 0) { 199 error_setg(errp, "missing hostname in URI"); 200 goto err; 201 } 202 203 if (!uri->path || strcmp(uri->path, "") == 0) { 204 error_setg(errp, "missing remote path in URI"); 205 goto err; 206 } 207 208 qp = query_params_parse(uri->query); 209 if (!qp) { 210 error_setg(errp, "could not parse query parameters"); 211 goto err; 212 } 213 214 if(uri->user && strcmp(uri->user, "") != 0) { 215 qdict_put_str(options, "user", uri->user); 216 } 217 218 qdict_put_str(options, "server.host", uri->server); 219 220 port_str = g_strdup_printf("%d", uri->port ?: 22); 221 qdict_put_str(options, "server.port", port_str); 222 g_free(port_str); 223 224 qdict_put_str(options, "path", uri->path); 225 226 /* Pick out any query parameters that we understand, and ignore 227 * the rest. 228 */ 229 for (i = 0; i < qp->n; ++i) { 230 if (strcmp(qp->p[i].name, "host_key_check") == 0) { 231 qdict_put_str(options, "host_key_check", qp->p[i].value); 232 } 233 } 234 235 query_params_free(qp); 236 uri_free(uri); 237 return 0; 238 239 err: 240 uri_free(uri); 241 return -EINVAL; 242 } 243 244 static bool ssh_has_filename_options_conflict(QDict *options, Error **errp) 245 { 246 const QDictEntry *qe; 247 248 for (qe = qdict_first(options); qe; qe = qdict_next(options, qe)) { 249 if (!strcmp(qe->key, "host") || 250 !strcmp(qe->key, "port") || 251 !strcmp(qe->key, "path") || 252 !strcmp(qe->key, "user") || 253 !strcmp(qe->key, "host_key_check") || 254 strstart(qe->key, "server.", NULL)) 255 { 256 error_setg(errp, "Option '%s' cannot be used with a file name", 257 qe->key); 258 return true; 259 } 260 } 261 262 return false; 263 } 264 265 static void ssh_parse_filename(const char *filename, QDict *options, 266 Error **errp) 267 { 268 if (ssh_has_filename_options_conflict(options, errp)) { 269 return; 270 } 271 272 parse_uri(filename, options, errp); 273 } 274 275 static int check_host_key_knownhosts(BDRVSSHState *s, Error **errp) 276 { 277 int ret; 278 enum ssh_known_hosts_e state; 279 int r; 280 ssh_key pubkey; 281 enum ssh_keytypes_e pubkey_type; 282 unsigned char *server_hash = NULL; 283 size_t server_hash_len; 284 char *fingerprint = NULL; 285 286 state = ssh_session_is_known_server(s->session); 287 trace_ssh_server_status(state); 288 289 switch (state) { 290 case SSH_KNOWN_HOSTS_OK: 291 /* OK */ 292 trace_ssh_check_host_key_knownhosts(); 293 break; 294 case SSH_KNOWN_HOSTS_CHANGED: 295 ret = -EINVAL; 296 r = ssh_get_server_publickey(s->session, &pubkey); 297 if (r == 0) { 298 r = ssh_get_publickey_hash(pubkey, SSH_PUBLICKEY_HASH_SHA256, 299 &server_hash, &server_hash_len); 300 pubkey_type = ssh_key_type(pubkey); 301 ssh_key_free(pubkey); 302 } 303 if (r == 0) { 304 fingerprint = ssh_get_fingerprint_hash(SSH_PUBLICKEY_HASH_SHA256, 305 server_hash, 306 server_hash_len); 307 ssh_clean_pubkey_hash(&server_hash); 308 } 309 if (fingerprint) { 310 error_setg(errp, 311 "host key (%s key with fingerprint %s) does not match " 312 "the one in known_hosts; this may be a possible attack", 313 ssh_key_type_to_char(pubkey_type), fingerprint); 314 ssh_string_free_char(fingerprint); 315 } else { 316 error_setg(errp, 317 "host key does not match the one in known_hosts; this " 318 "may be a possible attack"); 319 } 320 goto out; 321 case SSH_KNOWN_HOSTS_OTHER: 322 ret = -EINVAL; 323 error_setg(errp, 324 "host key for this server not found, another type exists"); 325 goto out; 326 case SSH_KNOWN_HOSTS_UNKNOWN: 327 ret = -EINVAL; 328 error_setg(errp, "no host key was found in known_hosts"); 329 goto out; 330 case SSH_KNOWN_HOSTS_NOT_FOUND: 331 ret = -ENOENT; 332 error_setg(errp, "known_hosts file not found"); 333 goto out; 334 case SSH_KNOWN_HOSTS_ERROR: 335 ret = -EINVAL; 336 error_setg(errp, "error while checking the host"); 337 goto out; 338 default: 339 ret = -EINVAL; 340 error_setg(errp, "error while checking for known server (%d)", state); 341 goto out; 342 } 343 344 /* known_hosts checking successful. */ 345 ret = 0; 346 347 out: 348 return ret; 349 } 350 351 static unsigned hex2decimal(char ch) 352 { 353 if (ch >= '0' && ch <= '9') { 354 return (ch - '0'); 355 } else if (ch >= 'a' && ch <= 'f') { 356 return 10 + (ch - 'a'); 357 } else if (ch >= 'A' && ch <= 'F') { 358 return 10 + (ch - 'A'); 359 } 360 361 return -1; 362 } 363 364 /* Compare the binary fingerprint (hash of host key) with the 365 * host_key_check parameter. 366 */ 367 static int compare_fingerprint(const unsigned char *fingerprint, size_t len, 368 const char *host_key_check) 369 { 370 unsigned c; 371 372 while (len > 0) { 373 while (*host_key_check == ':') 374 host_key_check++; 375 if (!qemu_isxdigit(host_key_check[0]) || 376 !qemu_isxdigit(host_key_check[1])) 377 return 1; 378 c = hex2decimal(host_key_check[0]) * 16 + 379 hex2decimal(host_key_check[1]); 380 if (c - *fingerprint != 0) 381 return c - *fingerprint; 382 fingerprint++; 383 len--; 384 host_key_check += 2; 385 } 386 return *host_key_check - '\0'; 387 } 388 389 static char *format_fingerprint(const unsigned char *fingerprint, size_t len) 390 { 391 static const char *hex = "0123456789abcdef"; 392 char *ret = g_new0(char, (len * 2) + 1); 393 for (size_t i = 0; i < len; i++) { 394 ret[i * 2] = hex[((fingerprint[i] >> 4) & 0xf)]; 395 ret[(i * 2) + 1] = hex[(fingerprint[i] & 0xf)]; 396 } 397 ret[len * 2] = '\0'; 398 return ret; 399 } 400 401 static int 402 check_host_key_hash(BDRVSSHState *s, const char *hash, 403 enum ssh_publickey_hash_type type, const char *typestr, 404 Error **errp) 405 { 406 int r; 407 ssh_key pubkey; 408 unsigned char *server_hash; 409 size_t server_hash_len; 410 const char *keytype; 411 412 r = ssh_get_server_publickey(s->session, &pubkey); 413 if (r != SSH_OK) { 414 session_error_setg(errp, s, "failed to read remote host key"); 415 return -EINVAL; 416 } 417 418 keytype = ssh_key_type_to_char(ssh_key_type(pubkey)); 419 420 r = ssh_get_publickey_hash(pubkey, type, &server_hash, &server_hash_len); 421 ssh_key_free(pubkey); 422 if (r != 0) { 423 session_error_setg(errp, s, 424 "failed reading the hash of the server SSH key"); 425 return -EINVAL; 426 } 427 428 r = compare_fingerprint(server_hash, server_hash_len, hash); 429 if (r != 0) { 430 g_autofree char *server_fp = format_fingerprint(server_hash, 431 server_hash_len); 432 error_setg(errp, "remote host %s key fingerprint '%s:%s' " 433 "does not match host_key_check '%s:%s'", 434 keytype, typestr, server_fp, typestr, hash); 435 ssh_clean_pubkey_hash(&server_hash); 436 return -EPERM; 437 } 438 ssh_clean_pubkey_hash(&server_hash); 439 440 return 0; 441 } 442 443 static int check_host_key(BDRVSSHState *s, SshHostKeyCheck *hkc, Error **errp) 444 { 445 SshHostKeyCheckMode mode; 446 447 if (hkc) { 448 mode = hkc->mode; 449 } else { 450 mode = SSH_HOST_KEY_CHECK_MODE_KNOWN_HOSTS; 451 } 452 453 switch (mode) { 454 case SSH_HOST_KEY_CHECK_MODE_NONE: 455 return 0; 456 case SSH_HOST_KEY_CHECK_MODE_HASH: 457 if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_MD5) { 458 return check_host_key_hash(s, hkc->u.hash.hash, 459 SSH_PUBLICKEY_HASH_MD5, "md5", 460 errp); 461 } else if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_SHA1) { 462 return check_host_key_hash(s, hkc->u.hash.hash, 463 SSH_PUBLICKEY_HASH_SHA1, "sha1", 464 errp); 465 } else if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_SHA256) { 466 return check_host_key_hash(s, hkc->u.hash.hash, 467 SSH_PUBLICKEY_HASH_SHA256, "sha256", 468 errp); 469 } 470 g_assert_not_reached(); 471 break; 472 case SSH_HOST_KEY_CHECK_MODE_KNOWN_HOSTS: 473 return check_host_key_knownhosts(s, errp); 474 default: 475 g_assert_not_reached(); 476 } 477 478 return -EINVAL; 479 } 480 481 static int authenticate(BDRVSSHState *s, Error **errp) 482 { 483 int r, ret; 484 int method; 485 486 /* Try to authenticate with the "none" method. */ 487 r = ssh_userauth_none(s->session, NULL); 488 if (r == SSH_AUTH_ERROR) { 489 ret = -EPERM; 490 session_error_setg(errp, s, "failed to authenticate using none " 491 "authentication"); 492 goto out; 493 } else if (r == SSH_AUTH_SUCCESS) { 494 /* Authenticated! */ 495 ret = 0; 496 goto out; 497 } 498 499 method = ssh_userauth_list(s->session, NULL); 500 trace_ssh_auth_methods(method); 501 502 /* 503 * Try to authenticate with publickey, using the ssh-agent 504 * if available. 505 */ 506 if (method & SSH_AUTH_METHOD_PUBLICKEY) { 507 r = ssh_userauth_publickey_auto(s->session, NULL, NULL); 508 if (r == SSH_AUTH_ERROR) { 509 ret = -EINVAL; 510 session_error_setg(errp, s, "failed to authenticate using " 511 "publickey authentication"); 512 goto out; 513 } else if (r == SSH_AUTH_SUCCESS) { 514 /* Authenticated! */ 515 ret = 0; 516 goto out; 517 } 518 } 519 520 ret = -EPERM; 521 error_setg(errp, "failed to authenticate using publickey authentication " 522 "and the identities held by your ssh-agent"); 523 524 out: 525 return ret; 526 } 527 528 static QemuOptsList ssh_runtime_opts = { 529 .name = "ssh", 530 .head = QTAILQ_HEAD_INITIALIZER(ssh_runtime_opts.head), 531 .desc = { 532 { 533 .name = "host", 534 .type = QEMU_OPT_STRING, 535 .help = "Host to connect to", 536 }, 537 { 538 .name = "port", 539 .type = QEMU_OPT_NUMBER, 540 .help = "Port to connect to", 541 }, 542 { 543 .name = "host_key_check", 544 .type = QEMU_OPT_STRING, 545 .help = "Defines how and what to check the host key against", 546 }, 547 { /* end of list */ } 548 }, 549 }; 550 551 static bool ssh_process_legacy_options(QDict *output_opts, 552 QemuOpts *legacy_opts, 553 Error **errp) 554 { 555 const char *host = qemu_opt_get(legacy_opts, "host"); 556 const char *port = qemu_opt_get(legacy_opts, "port"); 557 const char *host_key_check = qemu_opt_get(legacy_opts, "host_key_check"); 558 559 if (!host && port) { 560 error_setg(errp, "port may not be used without host"); 561 return false; 562 } 563 564 if (host) { 565 qdict_put_str(output_opts, "server.host", host); 566 qdict_put_str(output_opts, "server.port", port ?: stringify(22)); 567 } 568 569 if (host_key_check) { 570 if (strcmp(host_key_check, "no") == 0) { 571 qdict_put_str(output_opts, "host-key-check.mode", "none"); 572 } else if (strncmp(host_key_check, "md5:", 4) == 0) { 573 qdict_put_str(output_opts, "host-key-check.mode", "hash"); 574 qdict_put_str(output_opts, "host-key-check.type", "md5"); 575 qdict_put_str(output_opts, "host-key-check.hash", 576 &host_key_check[4]); 577 } else if (strncmp(host_key_check, "sha1:", 5) == 0) { 578 qdict_put_str(output_opts, "host-key-check.mode", "hash"); 579 qdict_put_str(output_opts, "host-key-check.type", "sha1"); 580 qdict_put_str(output_opts, "host-key-check.hash", 581 &host_key_check[5]); 582 } else if (strncmp(host_key_check, "sha256:", 7) == 0) { 583 qdict_put_str(output_opts, "host-key-check.mode", "hash"); 584 qdict_put_str(output_opts, "host-key-check.type", "sha256"); 585 qdict_put_str(output_opts, "host-key-check.hash", 586 &host_key_check[7]); 587 } else if (strcmp(host_key_check, "yes") == 0) { 588 qdict_put_str(output_opts, "host-key-check.mode", "known_hosts"); 589 } else { 590 error_setg(errp, "unknown host_key_check setting (%s)", 591 host_key_check); 592 return false; 593 } 594 } 595 596 return true; 597 } 598 599 static BlockdevOptionsSsh *ssh_parse_options(QDict *options, Error **errp) 600 { 601 BlockdevOptionsSsh *result = NULL; 602 QemuOpts *opts = NULL; 603 const QDictEntry *e; 604 Visitor *v; 605 606 /* Translate legacy options */ 607 opts = qemu_opts_create(&ssh_runtime_opts, NULL, 0, &error_abort); 608 if (!qemu_opts_absorb_qdict(opts, options, errp)) { 609 goto fail; 610 } 611 612 if (!ssh_process_legacy_options(options, opts, errp)) { 613 goto fail; 614 } 615 616 /* Create the QAPI object */ 617 v = qobject_input_visitor_new_flat_confused(options, errp); 618 if (!v) { 619 goto fail; 620 } 621 622 visit_type_BlockdevOptionsSsh(v, NULL, &result, errp); 623 visit_free(v); 624 if (!result) { 625 goto fail; 626 } 627 628 /* Remove the processed options from the QDict (the visitor processes 629 * _all_ options in the QDict) */ 630 while ((e = qdict_first(options))) { 631 qdict_del(options, e->key); 632 } 633 634 fail: 635 qemu_opts_del(opts); 636 return result; 637 } 638 639 static int connect_to_ssh(BDRVSSHState *s, BlockdevOptionsSsh *opts, 640 int ssh_flags, int creat_mode, Error **errp) 641 { 642 int r, ret; 643 unsigned int port = 0; 644 int new_sock = -1; 645 646 if (opts->has_user) { 647 s->user = g_strdup(opts->user); 648 } else { 649 s->user = g_strdup(g_get_user_name()); 650 if (!s->user) { 651 error_setg_errno(errp, errno, "Can't get user name"); 652 ret = -errno; 653 goto err; 654 } 655 } 656 657 /* Pop the config into our state object, Exit if invalid */ 658 s->inet = opts->server; 659 opts->server = NULL; 660 661 if (qemu_strtoui(s->inet->port, NULL, 10, &port) < 0) { 662 error_setg(errp, "Use only numeric port value"); 663 ret = -EINVAL; 664 goto err; 665 } 666 667 /* Open the socket and connect. */ 668 new_sock = inet_connect_saddr(s->inet, errp); 669 if (new_sock < 0) { 670 ret = -EIO; 671 goto err; 672 } 673 674 /* 675 * Try to disable the Nagle algorithm on TCP sockets to reduce latency, 676 * but do not fail if it cannot be disabled. 677 */ 678 r = socket_set_nodelay(new_sock); 679 if (r < 0) { 680 warn_report("can't set TCP_NODELAY for the ssh server %s: %s", 681 s->inet->host, strerror(errno)); 682 } 683 684 /* Create SSH session. */ 685 s->session = ssh_new(); 686 if (!s->session) { 687 ret = -EINVAL; 688 session_error_setg(errp, s, "failed to initialize libssh session"); 689 goto err; 690 } 691 692 /* 693 * Make sure we are in blocking mode during the connection and 694 * authentication phases. 695 */ 696 ssh_set_blocking(s->session, 1); 697 698 r = ssh_options_set(s->session, SSH_OPTIONS_USER, s->user); 699 if (r < 0) { 700 ret = -EINVAL; 701 session_error_setg(errp, s, 702 "failed to set the user in the libssh session"); 703 goto err; 704 } 705 706 r = ssh_options_set(s->session, SSH_OPTIONS_HOST, s->inet->host); 707 if (r < 0) { 708 ret = -EINVAL; 709 session_error_setg(errp, s, 710 "failed to set the host in the libssh session"); 711 goto err; 712 } 713 714 if (port > 0) { 715 r = ssh_options_set(s->session, SSH_OPTIONS_PORT, &port); 716 if (r < 0) { 717 ret = -EINVAL; 718 session_error_setg(errp, s, 719 "failed to set the port in the libssh session"); 720 goto err; 721 } 722 } 723 724 r = ssh_options_set(s->session, SSH_OPTIONS_COMPRESSION, "none"); 725 if (r < 0) { 726 ret = -EINVAL; 727 session_error_setg(errp, s, 728 "failed to disable the compression in the libssh " 729 "session"); 730 goto err; 731 } 732 733 /* Read ~/.ssh/config. */ 734 r = ssh_options_parse_config(s->session, NULL); 735 if (r < 0) { 736 ret = -EINVAL; 737 session_error_setg(errp, s, "failed to parse ~/.ssh/config"); 738 goto err; 739 } 740 741 r = ssh_options_set(s->session, SSH_OPTIONS_FD, &new_sock); 742 if (r < 0) { 743 ret = -EINVAL; 744 session_error_setg(errp, s, 745 "failed to set the socket in the libssh session"); 746 goto err; 747 } 748 /* libssh took ownership of the socket. */ 749 s->sock = new_sock; 750 new_sock = -1; 751 752 /* Connect. */ 753 r = ssh_connect(s->session); 754 if (r != SSH_OK) { 755 ret = -EINVAL; 756 session_error_setg(errp, s, "failed to establish SSH session"); 757 goto err; 758 } 759 760 /* Check the remote host's key against known_hosts. */ 761 ret = check_host_key(s, opts->host_key_check, errp); 762 if (ret < 0) { 763 goto err; 764 } 765 766 /* Authenticate. */ 767 ret = authenticate(s, errp); 768 if (ret < 0) { 769 goto err; 770 } 771 772 /* Start SFTP. */ 773 s->sftp = sftp_new(s->session); 774 if (!s->sftp) { 775 session_error_setg(errp, s, "failed to create sftp handle"); 776 ret = -EINVAL; 777 goto err; 778 } 779 780 r = sftp_init(s->sftp); 781 if (r < 0) { 782 sftp_error_setg(errp, s, "failed to initialize sftp handle"); 783 ret = -EINVAL; 784 goto err; 785 } 786 787 /* Open the remote file. */ 788 trace_ssh_connect_to_ssh(opts->path, ssh_flags, creat_mode); 789 s->sftp_handle = sftp_open(s->sftp, opts->path, ssh_flags, creat_mode); 790 if (!s->sftp_handle) { 791 sftp_error_setg(errp, s, "failed to open remote file '%s'", 792 opts->path); 793 ret = -EINVAL; 794 goto err; 795 } 796 797 /* Make sure the SFTP file is handled in blocking mode. */ 798 sftp_file_set_blocking(s->sftp_handle); 799 800 s->attrs = sftp_fstat(s->sftp_handle); 801 if (!s->attrs) { 802 sftp_error_setg(errp, s, "failed to read file attributes"); 803 return -EINVAL; 804 } 805 806 return 0; 807 808 err: 809 if (s->attrs) { 810 sftp_attributes_free(s->attrs); 811 } 812 s->attrs = NULL; 813 if (s->sftp_handle) { 814 sftp_close(s->sftp_handle); 815 } 816 s->sftp_handle = NULL; 817 if (s->sftp) { 818 sftp_free(s->sftp); 819 } 820 s->sftp = NULL; 821 if (s->session) { 822 ssh_disconnect(s->session); 823 ssh_free(s->session); 824 } 825 s->session = NULL; 826 s->sock = -1; 827 if (new_sock >= 0) { 828 close(new_sock); 829 } 830 831 return ret; 832 } 833 834 static int ssh_file_open(BlockDriverState *bs, QDict *options, int bdrv_flags, 835 Error **errp) 836 { 837 BDRVSSHState *s = bs->opaque; 838 BlockdevOptionsSsh *opts; 839 int ret; 840 int ssh_flags; 841 842 ssh_state_init(s); 843 844 ssh_flags = 0; 845 if (bdrv_flags & BDRV_O_RDWR) { 846 ssh_flags |= O_RDWR; 847 } else { 848 ssh_flags |= O_RDONLY; 849 } 850 851 opts = ssh_parse_options(options, errp); 852 if (opts == NULL) { 853 return -EINVAL; 854 } 855 856 /* Start up SSH. */ 857 ret = connect_to_ssh(s, opts, ssh_flags, 0, errp); 858 if (ret < 0) { 859 goto err; 860 } 861 862 /* Go non-blocking. */ 863 ssh_set_blocking(s->session, 0); 864 865 if (s->attrs->type == SSH_FILEXFER_TYPE_REGULAR) { 866 bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE; 867 } 868 869 qapi_free_BlockdevOptionsSsh(opts); 870 871 return 0; 872 873 err: 874 qapi_free_BlockdevOptionsSsh(opts); 875 876 return ret; 877 } 878 879 /* Note: This is a blocking operation */ 880 static int ssh_grow_file(BDRVSSHState *s, int64_t offset, Error **errp) 881 { 882 ssize_t ret; 883 char c[1] = { '\0' }; 884 int was_blocking = ssh_is_blocking(s->session); 885 886 /* offset must be strictly greater than the current size so we do 887 * not overwrite anything */ 888 assert(offset > 0 && offset > s->attrs->size); 889 890 ssh_set_blocking(s->session, 1); 891 892 sftp_seek64(s->sftp_handle, offset - 1); 893 ret = sftp_write(s->sftp_handle, c, 1); 894 895 ssh_set_blocking(s->session, was_blocking); 896 897 if (ret < 0) { 898 sftp_error_setg(errp, s, "Failed to grow file"); 899 return -EIO; 900 } 901 902 s->attrs->size = offset; 903 return 0; 904 } 905 906 static QemuOptsList ssh_create_opts = { 907 .name = "ssh-create-opts", 908 .head = QTAILQ_HEAD_INITIALIZER(ssh_create_opts.head), 909 .desc = { 910 { 911 .name = BLOCK_OPT_SIZE, 912 .type = QEMU_OPT_SIZE, 913 .help = "Virtual disk size" 914 }, 915 { /* end of list */ } 916 } 917 }; 918 919 static int ssh_co_create(BlockdevCreateOptions *options, Error **errp) 920 { 921 BlockdevCreateOptionsSsh *opts = &options->u.ssh; 922 BDRVSSHState s; 923 int ret; 924 925 assert(options->driver == BLOCKDEV_DRIVER_SSH); 926 927 ssh_state_init(&s); 928 929 ret = connect_to_ssh(&s, opts->location, 930 O_RDWR | O_CREAT | O_TRUNC, 931 0644, errp); 932 if (ret < 0) { 933 goto fail; 934 } 935 936 if (opts->size > 0) { 937 ret = ssh_grow_file(&s, opts->size, errp); 938 if (ret < 0) { 939 goto fail; 940 } 941 } 942 943 ret = 0; 944 fail: 945 ssh_state_free(&s); 946 return ret; 947 } 948 949 static int coroutine_fn ssh_co_create_opts(BlockDriver *drv, 950 const char *filename, 951 QemuOpts *opts, 952 Error **errp) 953 { 954 BlockdevCreateOptions *create_options; 955 BlockdevCreateOptionsSsh *ssh_opts; 956 int ret; 957 QDict *uri_options = NULL; 958 959 create_options = g_new0(BlockdevCreateOptions, 1); 960 create_options->driver = BLOCKDEV_DRIVER_SSH; 961 ssh_opts = &create_options->u.ssh; 962 963 /* Get desired file size. */ 964 ssh_opts->size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0), 965 BDRV_SECTOR_SIZE); 966 trace_ssh_co_create_opts(ssh_opts->size); 967 968 uri_options = qdict_new(); 969 ret = parse_uri(filename, uri_options, errp); 970 if (ret < 0) { 971 goto out; 972 } 973 974 ssh_opts->location = ssh_parse_options(uri_options, errp); 975 if (ssh_opts->location == NULL) { 976 ret = -EINVAL; 977 goto out; 978 } 979 980 ret = ssh_co_create(create_options, errp); 981 982 out: 983 qobject_unref(uri_options); 984 qapi_free_BlockdevCreateOptions(create_options); 985 return ret; 986 } 987 988 static void ssh_close(BlockDriverState *bs) 989 { 990 BDRVSSHState *s = bs->opaque; 991 992 ssh_state_free(s); 993 } 994 995 static int ssh_has_zero_init(BlockDriverState *bs) 996 { 997 BDRVSSHState *s = bs->opaque; 998 /* Assume false, unless we can positively prove it's true. */ 999 int has_zero_init = 0; 1000 1001 if (s->attrs->type == SSH_FILEXFER_TYPE_REGULAR) { 1002 has_zero_init = 1; 1003 } 1004 1005 return has_zero_init; 1006 } 1007 1008 typedef struct BDRVSSHRestart { 1009 BlockDriverState *bs; 1010 Coroutine *co; 1011 } BDRVSSHRestart; 1012 1013 static void restart_coroutine(void *opaque) 1014 { 1015 BDRVSSHRestart *restart = opaque; 1016 BlockDriverState *bs = restart->bs; 1017 BDRVSSHState *s = bs->opaque; 1018 AioContext *ctx = bdrv_get_aio_context(bs); 1019 1020 trace_ssh_restart_coroutine(restart->co); 1021 aio_set_fd_handler(ctx, s->sock, false, NULL, NULL, NULL, NULL, NULL); 1022 1023 aio_co_wake(restart->co); 1024 } 1025 1026 /* A non-blocking call returned EAGAIN, so yield, ensuring the 1027 * handlers are set up so that we'll be rescheduled when there is an 1028 * interesting event on the socket. 1029 */ 1030 static coroutine_fn void co_yield(BDRVSSHState *s, BlockDriverState *bs) 1031 { 1032 int r; 1033 IOHandler *rd_handler = NULL, *wr_handler = NULL; 1034 BDRVSSHRestart restart = { 1035 .bs = bs, 1036 .co = qemu_coroutine_self() 1037 }; 1038 1039 r = ssh_get_poll_flags(s->session); 1040 1041 if (r & SSH_READ_PENDING) { 1042 rd_handler = restart_coroutine; 1043 } 1044 if (r & SSH_WRITE_PENDING) { 1045 wr_handler = restart_coroutine; 1046 } 1047 1048 trace_ssh_co_yield(s->sock, rd_handler, wr_handler); 1049 1050 aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock, 1051 false, rd_handler, wr_handler, NULL, NULL, &restart); 1052 qemu_coroutine_yield(); 1053 trace_ssh_co_yield_back(s->sock); 1054 } 1055 1056 static coroutine_fn int ssh_read(BDRVSSHState *s, BlockDriverState *bs, 1057 int64_t offset, size_t size, 1058 QEMUIOVector *qiov) 1059 { 1060 ssize_t r; 1061 size_t got; 1062 char *buf, *end_of_vec; 1063 struct iovec *i; 1064 1065 trace_ssh_read(offset, size); 1066 1067 trace_ssh_seek(offset); 1068 sftp_seek64(s->sftp_handle, offset); 1069 1070 /* This keeps track of the current iovec element ('i'), where we 1071 * will write to next ('buf'), and the end of the current iovec 1072 * ('end_of_vec'). 1073 */ 1074 i = &qiov->iov[0]; 1075 buf = i->iov_base; 1076 end_of_vec = i->iov_base + i->iov_len; 1077 1078 for (got = 0; got < size; ) { 1079 size_t request_read_size; 1080 again: 1081 /* 1082 * The size of SFTP packets is limited to 32K bytes, so limit 1083 * the amount of data requested to 16K, as libssh currently 1084 * does not handle multiple requests on its own. 1085 */ 1086 request_read_size = MIN(end_of_vec - buf, 16384); 1087 trace_ssh_read_buf(buf, end_of_vec - buf, request_read_size); 1088 r = sftp_read(s->sftp_handle, buf, request_read_size); 1089 trace_ssh_read_return(r, sftp_get_error(s->sftp)); 1090 1091 if (r == SSH_AGAIN) { 1092 co_yield(s, bs); 1093 goto again; 1094 } 1095 if (r == SSH_EOF || (r == 0 && sftp_get_error(s->sftp) == SSH_FX_EOF)) { 1096 /* EOF: Short read so pad the buffer with zeroes and return it. */ 1097 qemu_iovec_memset(qiov, got, 0, size - got); 1098 return 0; 1099 } 1100 if (r <= 0) { 1101 sftp_error_trace(s, "read"); 1102 return -EIO; 1103 } 1104 1105 got += r; 1106 buf += r; 1107 if (buf >= end_of_vec && got < size) { 1108 i++; 1109 buf = i->iov_base; 1110 end_of_vec = i->iov_base + i->iov_len; 1111 } 1112 } 1113 1114 return 0; 1115 } 1116 1117 static coroutine_fn int ssh_co_readv(BlockDriverState *bs, 1118 int64_t sector_num, 1119 int nb_sectors, QEMUIOVector *qiov) 1120 { 1121 BDRVSSHState *s = bs->opaque; 1122 int ret; 1123 1124 qemu_co_mutex_lock(&s->lock); 1125 ret = ssh_read(s, bs, sector_num * BDRV_SECTOR_SIZE, 1126 nb_sectors * BDRV_SECTOR_SIZE, qiov); 1127 qemu_co_mutex_unlock(&s->lock); 1128 1129 return ret; 1130 } 1131 1132 static int ssh_write(BDRVSSHState *s, BlockDriverState *bs, 1133 int64_t offset, size_t size, 1134 QEMUIOVector *qiov) 1135 { 1136 ssize_t r; 1137 size_t written; 1138 char *buf, *end_of_vec; 1139 struct iovec *i; 1140 1141 trace_ssh_write(offset, size); 1142 1143 trace_ssh_seek(offset); 1144 sftp_seek64(s->sftp_handle, offset); 1145 1146 /* This keeps track of the current iovec element ('i'), where we 1147 * will read from next ('buf'), and the end of the current iovec 1148 * ('end_of_vec'). 1149 */ 1150 i = &qiov->iov[0]; 1151 buf = i->iov_base; 1152 end_of_vec = i->iov_base + i->iov_len; 1153 1154 for (written = 0; written < size; ) { 1155 size_t request_write_size; 1156 again: 1157 /* 1158 * Avoid too large data packets, as libssh currently does not 1159 * handle multiple requests on its own. 1160 */ 1161 request_write_size = MIN(end_of_vec - buf, 131072); 1162 trace_ssh_write_buf(buf, end_of_vec - buf, request_write_size); 1163 r = sftp_write(s->sftp_handle, buf, request_write_size); 1164 trace_ssh_write_return(r, sftp_get_error(s->sftp)); 1165 1166 if (r == SSH_AGAIN) { 1167 co_yield(s, bs); 1168 goto again; 1169 } 1170 if (r < 0) { 1171 sftp_error_trace(s, "write"); 1172 return -EIO; 1173 } 1174 1175 written += r; 1176 buf += r; 1177 if (buf >= end_of_vec && written < size) { 1178 i++; 1179 buf = i->iov_base; 1180 end_of_vec = i->iov_base + i->iov_len; 1181 } 1182 1183 if (offset + written > s->attrs->size) { 1184 s->attrs->size = offset + written; 1185 } 1186 } 1187 1188 return 0; 1189 } 1190 1191 static coroutine_fn int ssh_co_writev(BlockDriverState *bs, 1192 int64_t sector_num, 1193 int nb_sectors, QEMUIOVector *qiov, 1194 int flags) 1195 { 1196 BDRVSSHState *s = bs->opaque; 1197 int ret; 1198 1199 assert(!flags); 1200 qemu_co_mutex_lock(&s->lock); 1201 ret = ssh_write(s, bs, sector_num * BDRV_SECTOR_SIZE, 1202 nb_sectors * BDRV_SECTOR_SIZE, qiov); 1203 qemu_co_mutex_unlock(&s->lock); 1204 1205 return ret; 1206 } 1207 1208 static void unsafe_flush_warning(BDRVSSHState *s, const char *what) 1209 { 1210 if (!s->unsafe_flush_warning) { 1211 warn_report("ssh server %s does not support fsync", 1212 s->inet->host); 1213 if (what) { 1214 error_report("to support fsync, you need %s", what); 1215 } 1216 s->unsafe_flush_warning = true; 1217 } 1218 } 1219 1220 static coroutine_fn int ssh_flush(BDRVSSHState *s, BlockDriverState *bs) 1221 { 1222 int r; 1223 1224 trace_ssh_flush(); 1225 1226 if (!sftp_extension_supported(s->sftp, "fsync@openssh.com", "1")) { 1227 unsafe_flush_warning(s, "OpenSSH >= 6.3"); 1228 return 0; 1229 } 1230 again: 1231 r = sftp_fsync(s->sftp_handle); 1232 if (r == SSH_AGAIN) { 1233 co_yield(s, bs); 1234 goto again; 1235 } 1236 if (r < 0) { 1237 sftp_error_trace(s, "fsync"); 1238 return -EIO; 1239 } 1240 1241 return 0; 1242 } 1243 1244 static coroutine_fn int ssh_co_flush(BlockDriverState *bs) 1245 { 1246 BDRVSSHState *s = bs->opaque; 1247 int ret; 1248 1249 qemu_co_mutex_lock(&s->lock); 1250 ret = ssh_flush(s, bs); 1251 qemu_co_mutex_unlock(&s->lock); 1252 1253 return ret; 1254 } 1255 1256 static int64_t ssh_getlength(BlockDriverState *bs) 1257 { 1258 BDRVSSHState *s = bs->opaque; 1259 int64_t length; 1260 1261 /* Note we cannot make a libssh call here. */ 1262 length = (int64_t) s->attrs->size; 1263 trace_ssh_getlength(length); 1264 1265 return length; 1266 } 1267 1268 static int coroutine_fn ssh_co_truncate(BlockDriverState *bs, int64_t offset, 1269 bool exact, PreallocMode prealloc, 1270 BdrvRequestFlags flags, Error **errp) 1271 { 1272 BDRVSSHState *s = bs->opaque; 1273 1274 if (prealloc != PREALLOC_MODE_OFF) { 1275 error_setg(errp, "Unsupported preallocation mode '%s'", 1276 PreallocMode_str(prealloc)); 1277 return -ENOTSUP; 1278 } 1279 1280 if (offset < s->attrs->size) { 1281 error_setg(errp, "ssh driver does not support shrinking files"); 1282 return -ENOTSUP; 1283 } 1284 1285 if (offset == s->attrs->size) { 1286 return 0; 1287 } 1288 1289 return ssh_grow_file(s, offset, errp); 1290 } 1291 1292 static void ssh_refresh_filename(BlockDriverState *bs) 1293 { 1294 BDRVSSHState *s = bs->opaque; 1295 const char *path, *host_key_check; 1296 int ret; 1297 1298 /* 1299 * None of these options can be represented in a plain "host:port" 1300 * format, so if any was given, we have to abort. 1301 */ 1302 if (s->inet->has_ipv4 || s->inet->has_ipv6 || s->inet->has_to || 1303 s->inet->has_numeric) 1304 { 1305 return; 1306 } 1307 1308 path = qdict_get_try_str(bs->full_open_options, "path"); 1309 assert(path); /* mandatory option */ 1310 1311 host_key_check = qdict_get_try_str(bs->full_open_options, "host_key_check"); 1312 1313 ret = snprintf(bs->exact_filename, sizeof(bs->exact_filename), 1314 "ssh://%s@%s:%s%s%s%s", 1315 s->user, s->inet->host, s->inet->port, path, 1316 host_key_check ? "?host_key_check=" : "", 1317 host_key_check ?: ""); 1318 if (ret >= sizeof(bs->exact_filename)) { 1319 /* An overflow makes the filename unusable, so do not report any */ 1320 bs->exact_filename[0] = '\0'; 1321 } 1322 } 1323 1324 static char *ssh_bdrv_dirname(BlockDriverState *bs, Error **errp) 1325 { 1326 if (qdict_haskey(bs->full_open_options, "host_key_check")) { 1327 /* 1328 * We cannot generate a simple prefix if we would have to 1329 * append a query string. 1330 */ 1331 error_setg(errp, 1332 "Cannot generate a base directory with host_key_check set"); 1333 return NULL; 1334 } 1335 1336 if (bs->exact_filename[0] == '\0') { 1337 error_setg(errp, "Cannot generate a base directory for this ssh node"); 1338 return NULL; 1339 } 1340 1341 return path_combine(bs->exact_filename, ""); 1342 } 1343 1344 static const char *const ssh_strong_runtime_opts[] = { 1345 "host", 1346 "port", 1347 "path", 1348 "user", 1349 "host_key_check", 1350 "server.", 1351 1352 NULL 1353 }; 1354 1355 static BlockDriver bdrv_ssh = { 1356 .format_name = "ssh", 1357 .protocol_name = "ssh", 1358 .instance_size = sizeof(BDRVSSHState), 1359 .bdrv_parse_filename = ssh_parse_filename, 1360 .bdrv_file_open = ssh_file_open, 1361 .bdrv_co_create = ssh_co_create, 1362 .bdrv_co_create_opts = ssh_co_create_opts, 1363 .bdrv_close = ssh_close, 1364 .bdrv_has_zero_init = ssh_has_zero_init, 1365 .bdrv_co_readv = ssh_co_readv, 1366 .bdrv_co_writev = ssh_co_writev, 1367 .bdrv_getlength = ssh_getlength, 1368 .bdrv_co_truncate = ssh_co_truncate, 1369 .bdrv_co_flush_to_disk = ssh_co_flush, 1370 .bdrv_refresh_filename = ssh_refresh_filename, 1371 .bdrv_dirname = ssh_bdrv_dirname, 1372 .create_opts = &ssh_create_opts, 1373 .strong_runtime_opts = ssh_strong_runtime_opts, 1374 }; 1375 1376 static void bdrv_ssh_init(void) 1377 { 1378 int r; 1379 1380 r = ssh_init(); 1381 if (r != 0) { 1382 fprintf(stderr, "libssh initialization failed, %d\n", r); 1383 exit(EXIT_FAILURE); 1384 } 1385 1386 #if TRACE_LIBSSH != 0 1387 ssh_set_log_level(TRACE_LIBSSH); 1388 #endif 1389 1390 bdrv_register(&bdrv_ssh); 1391 } 1392 1393 block_init(bdrv_ssh_init); 1394