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 "qemu/uri.h" 41 #include "qapi/qapi-visit-sockets.h" 42 #include "qapi/qapi-visit-block-core.h" 43 #include "qapi/qmp/qdict.h" 44 #include "qapi/qmp/qstring.h" 45 #include "qapi/qobject-input-visitor.h" 46 #include "qapi/qobject-output-visitor.h" 47 #include "trace.h" 48 49 /* 50 * TRACE_LIBSSH=<level> enables tracing in libssh itself. 51 * The meaning of <level> is described here: 52 * http://api.libssh.org/master/group__libssh__log.html 53 */ 54 #define TRACE_LIBSSH 0 /* see: SSH_LOG_* */ 55 56 typedef struct BDRVSSHState { 57 /* Coroutine. */ 58 CoMutex lock; 59 60 /* SSH connection. */ 61 int sock; /* socket */ 62 ssh_session session; /* ssh session */ 63 sftp_session sftp; /* sftp session */ 64 sftp_file sftp_handle; /* sftp remote file handle */ 65 66 /* 67 * File attributes at open. We try to keep the .size field 68 * updated if it changes (eg by writing at the end of the file). 69 */ 70 sftp_attributes attrs; 71 72 InetSocketAddress *inet; 73 74 /* Used to warn if 'flush' is not supported. */ 75 bool unsafe_flush_warning; 76 77 /* 78 * Store the user name for ssh_refresh_filename() because the 79 * default depends on the system you are on -- therefore, when we 80 * generate a filename, it should always contain the user name we 81 * are actually using. 82 */ 83 char *user; 84 } BDRVSSHState; 85 86 static void ssh_state_init(BDRVSSHState *s) 87 { 88 memset(s, 0, sizeof *s); 89 s->sock = -1; 90 qemu_co_mutex_init(&s->lock); 91 } 92 93 static void ssh_state_free(BDRVSSHState *s) 94 { 95 g_free(s->user); 96 97 if (s->attrs) { 98 sftp_attributes_free(s->attrs); 99 } 100 if (s->sftp_handle) { 101 sftp_close(s->sftp_handle); 102 } 103 if (s->sftp) { 104 sftp_free(s->sftp); 105 } 106 if (s->session) { 107 ssh_disconnect(s->session); 108 ssh_free(s->session); /* This frees s->sock */ 109 } 110 } 111 112 static void G_GNUC_PRINTF(3, 4) 113 session_error_setg(Error **errp, BDRVSSHState *s, const char *fs, ...) 114 { 115 va_list args; 116 char *msg; 117 118 va_start(args, fs); 119 msg = g_strdup_vprintf(fs, args); 120 va_end(args); 121 122 if (s->session) { 123 const char *ssh_err; 124 int ssh_err_code; 125 126 /* This is not an errno. See <libssh/libssh.h>. */ 127 ssh_err = ssh_get_error(s->session); 128 ssh_err_code = ssh_get_error_code(s->session); 129 error_setg(errp, "%s: %s (libssh error code: %d)", 130 msg, ssh_err, ssh_err_code); 131 } else { 132 error_setg(errp, "%s", msg); 133 } 134 g_free(msg); 135 } 136 137 static void G_GNUC_PRINTF(3, 4) 138 sftp_error_setg(Error **errp, BDRVSSHState *s, const char *fs, ...) 139 { 140 va_list args; 141 char *msg; 142 143 va_start(args, fs); 144 msg = g_strdup_vprintf(fs, args); 145 va_end(args); 146 147 if (s->sftp) { 148 const char *ssh_err; 149 int ssh_err_code; 150 int sftp_err_code; 151 152 /* This is not an errno. See <libssh/libssh.h>. */ 153 ssh_err = ssh_get_error(s->session); 154 ssh_err_code = ssh_get_error_code(s->session); 155 /* See <libssh/sftp.h>. */ 156 sftp_err_code = sftp_get_error(s->sftp); 157 158 error_setg(errp, 159 "%s: %s (libssh error code: %d, sftp error code: %d)", 160 msg, ssh_err, ssh_err_code, sftp_err_code); 161 } else { 162 error_setg(errp, "%s", msg); 163 } 164 g_free(msg); 165 } 166 167 static void sftp_error_trace(BDRVSSHState *s, const char *op) 168 { 169 const char *ssh_err; 170 int ssh_err_code; 171 int sftp_err_code; 172 173 /* This is not an errno. See <libssh/libssh.h>. */ 174 ssh_err = ssh_get_error(s->session); 175 ssh_err_code = ssh_get_error_code(s->session); 176 /* See <libssh/sftp.h>. */ 177 sftp_err_code = sftp_get_error(s->sftp); 178 179 trace_sftp_error(op, ssh_err, ssh_err_code, sftp_err_code); 180 } 181 182 static int parse_uri(const char *filename, QDict *options, Error **errp) 183 { 184 URI *uri = NULL; 185 QueryParams *qp; 186 char *port_str; 187 int i; 188 189 uri = uri_parse(filename); 190 if (!uri) { 191 return -EINVAL; 192 } 193 194 if (g_strcmp0(uri->scheme, "ssh") != 0) { 195 error_setg(errp, "URI scheme must be 'ssh'"); 196 goto err; 197 } 198 199 if (!uri->server || strcmp(uri->server, "") == 0) { 200 error_setg(errp, "missing hostname in URI"); 201 goto err; 202 } 203 204 if (!uri->path || strcmp(uri->path, "") == 0) { 205 error_setg(errp, "missing remote path in URI"); 206 goto err; 207 } 208 209 qp = query_params_parse(uri->query); 210 if (!qp) { 211 error_setg(errp, "could not parse query parameters"); 212 goto err; 213 } 214 215 if(uri->user && strcmp(uri->user, "") != 0) { 216 qdict_put_str(options, "user", uri->user); 217 } 218 219 qdict_put_str(options, "server.host", uri->server); 220 221 port_str = g_strdup_printf("%d", uri->port ?: 22); 222 qdict_put_str(options, "server.port", port_str); 223 g_free(port_str); 224 225 qdict_put_str(options, "path", uri->path); 226 227 /* Pick out any query parameters that we understand, and ignore 228 * the rest. 229 */ 230 for (i = 0; i < qp->n; ++i) { 231 if (strcmp(qp->p[i].name, "host_key_check") == 0) { 232 qdict_put_str(options, "host_key_check", qp->p[i].value); 233 } 234 } 235 236 query_params_free(qp); 237 uri_free(uri); 238 return 0; 239 240 err: 241 uri_free(uri); 242 return -EINVAL; 243 } 244 245 static bool ssh_has_filename_options_conflict(QDict *options, Error **errp) 246 { 247 const QDictEntry *qe; 248 249 for (qe = qdict_first(options); qe; qe = qdict_next(options, qe)) { 250 if (!strcmp(qe->key, "host") || 251 !strcmp(qe->key, "port") || 252 !strcmp(qe->key, "path") || 253 !strcmp(qe->key, "user") || 254 !strcmp(qe->key, "host_key_check") || 255 strstart(qe->key, "server.", NULL)) 256 { 257 error_setg(errp, "Option '%s' cannot be used with a file name", 258 qe->key); 259 return true; 260 } 261 } 262 263 return false; 264 } 265 266 static void ssh_parse_filename(const char *filename, QDict *options, 267 Error **errp) 268 { 269 if (ssh_has_filename_options_conflict(options, errp)) { 270 return; 271 } 272 273 parse_uri(filename, options, errp); 274 } 275 276 static int check_host_key_knownhosts(BDRVSSHState *s, Error **errp) 277 { 278 int ret; 279 enum ssh_known_hosts_e state; 280 int r; 281 ssh_key pubkey; 282 enum ssh_keytypes_e pubkey_type; 283 unsigned char *server_hash = NULL; 284 size_t server_hash_len; 285 char *fingerprint = NULL; 286 287 state = ssh_session_is_known_server(s->session); 288 trace_ssh_server_status(state); 289 290 switch (state) { 291 case SSH_KNOWN_HOSTS_OK: 292 /* OK */ 293 trace_ssh_check_host_key_knownhosts(); 294 break; 295 case SSH_KNOWN_HOSTS_CHANGED: 296 ret = -EINVAL; 297 r = ssh_get_server_publickey(s->session, &pubkey); 298 if (r == 0) { 299 r = ssh_get_publickey_hash(pubkey, SSH_PUBLICKEY_HASH_SHA256, 300 &server_hash, &server_hash_len); 301 pubkey_type = ssh_key_type(pubkey); 302 ssh_key_free(pubkey); 303 } 304 if (r == 0) { 305 fingerprint = ssh_get_fingerprint_hash(SSH_PUBLICKEY_HASH_SHA256, 306 server_hash, 307 server_hash_len); 308 ssh_clean_pubkey_hash(&server_hash); 309 } 310 if (fingerprint) { 311 error_setg(errp, 312 "host key (%s key with fingerprint %s) does not match " 313 "the one in known_hosts; this may be a possible attack", 314 ssh_key_type_to_char(pubkey_type), fingerprint); 315 ssh_string_free_char(fingerprint); 316 } else { 317 error_setg(errp, 318 "host key does not match the one in known_hosts; this " 319 "may be a possible attack"); 320 } 321 goto out; 322 case SSH_KNOWN_HOSTS_OTHER: 323 ret = -EINVAL; 324 error_setg(errp, 325 "host key for this server not found, another type exists"); 326 goto out; 327 case SSH_KNOWN_HOSTS_UNKNOWN: 328 ret = -EINVAL; 329 error_setg(errp, "no host key was found in known_hosts"); 330 goto out; 331 case SSH_KNOWN_HOSTS_NOT_FOUND: 332 ret = -ENOENT; 333 error_setg(errp, "known_hosts file not found"); 334 goto out; 335 case SSH_KNOWN_HOSTS_ERROR: 336 ret = -EINVAL; 337 error_setg(errp, "error while checking the host"); 338 goto out; 339 default: 340 ret = -EINVAL; 341 error_setg(errp, "error while checking for known server (%d)", state); 342 goto out; 343 } 344 345 /* known_hosts checking successful. */ 346 ret = 0; 347 348 out: 349 return ret; 350 } 351 352 static unsigned hex2decimal(char ch) 353 { 354 if (ch >= '0' && ch <= '9') { 355 return (ch - '0'); 356 } else if (ch >= 'a' && ch <= 'f') { 357 return 10 + (ch - 'a'); 358 } else if (ch >= 'A' && ch <= 'F') { 359 return 10 + (ch - 'A'); 360 } 361 362 return -1; 363 } 364 365 /* Compare the binary fingerprint (hash of host key) with the 366 * host_key_check parameter. 367 */ 368 static int compare_fingerprint(const unsigned char *fingerprint, size_t len, 369 const char *host_key_check) 370 { 371 unsigned c; 372 373 while (len > 0) { 374 while (*host_key_check == ':') 375 host_key_check++; 376 if (!qemu_isxdigit(host_key_check[0]) || 377 !qemu_isxdigit(host_key_check[1])) 378 return 1; 379 c = hex2decimal(host_key_check[0]) * 16 + 380 hex2decimal(host_key_check[1]); 381 if (c - *fingerprint != 0) 382 return c - *fingerprint; 383 fingerprint++; 384 len--; 385 host_key_check += 2; 386 } 387 return *host_key_check - '\0'; 388 } 389 390 static char *format_fingerprint(const unsigned char *fingerprint, size_t len) 391 { 392 static const char *hex = "0123456789abcdef"; 393 char *ret = g_new0(char, (len * 2) + 1); 394 for (size_t i = 0; i < len; i++) { 395 ret[i * 2] = hex[((fingerprint[i] >> 4) & 0xf)]; 396 ret[(i * 2) + 1] = hex[(fingerprint[i] & 0xf)]; 397 } 398 ret[len * 2] = '\0'; 399 return ret; 400 } 401 402 static int 403 check_host_key_hash(BDRVSSHState *s, const char *hash, 404 enum ssh_publickey_hash_type type, const char *typestr, 405 Error **errp) 406 { 407 int r; 408 ssh_key pubkey; 409 unsigned char *server_hash; 410 size_t server_hash_len; 411 const char *keytype; 412 413 r = ssh_get_server_publickey(s->session, &pubkey); 414 if (r != SSH_OK) { 415 session_error_setg(errp, s, "failed to read remote host key"); 416 return -EINVAL; 417 } 418 419 keytype = ssh_key_type_to_char(ssh_key_type(pubkey)); 420 421 r = ssh_get_publickey_hash(pubkey, type, &server_hash, &server_hash_len); 422 ssh_key_free(pubkey); 423 if (r != 0) { 424 session_error_setg(errp, s, 425 "failed reading the hash of the server SSH key"); 426 return -EINVAL; 427 } 428 429 r = compare_fingerprint(server_hash, server_hash_len, hash); 430 if (r != 0) { 431 g_autofree char *server_fp = format_fingerprint(server_hash, 432 server_hash_len); 433 error_setg(errp, "remote host %s key fingerprint '%s:%s' " 434 "does not match host_key_check '%s:%s'", 435 keytype, typestr, server_fp, typestr, hash); 436 ssh_clean_pubkey_hash(&server_hash); 437 return -EPERM; 438 } 439 ssh_clean_pubkey_hash(&server_hash); 440 441 return 0; 442 } 443 444 static int check_host_key(BDRVSSHState *s, SshHostKeyCheck *hkc, Error **errp) 445 { 446 SshHostKeyCheckMode mode; 447 448 if (hkc) { 449 mode = hkc->mode; 450 } else { 451 mode = SSH_HOST_KEY_CHECK_MODE_KNOWN_HOSTS; 452 } 453 454 switch (mode) { 455 case SSH_HOST_KEY_CHECK_MODE_NONE: 456 return 0; 457 case SSH_HOST_KEY_CHECK_MODE_HASH: 458 if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_MD5) { 459 return check_host_key_hash(s, hkc->u.hash.hash, 460 SSH_PUBLICKEY_HASH_MD5, "md5", 461 errp); 462 } else if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_SHA1) { 463 return check_host_key_hash(s, hkc->u.hash.hash, 464 SSH_PUBLICKEY_HASH_SHA1, "sha1", 465 errp); 466 } else if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_SHA256) { 467 return check_host_key_hash(s, hkc->u.hash.hash, 468 SSH_PUBLICKEY_HASH_SHA256, "sha256", 469 errp); 470 } 471 g_assert_not_reached(); 472 break; 473 case SSH_HOST_KEY_CHECK_MODE_KNOWN_HOSTS: 474 return check_host_key_knownhosts(s, errp); 475 default: 476 g_assert_not_reached(); 477 } 478 479 return -EINVAL; 480 } 481 482 static int authenticate(BDRVSSHState *s, Error **errp) 483 { 484 int r, ret; 485 int method; 486 487 /* Try to authenticate with the "none" method. */ 488 r = ssh_userauth_none(s->session, NULL); 489 if (r == SSH_AUTH_ERROR) { 490 ret = -EPERM; 491 session_error_setg(errp, s, "failed to authenticate using none " 492 "authentication"); 493 goto out; 494 } else if (r == SSH_AUTH_SUCCESS) { 495 /* Authenticated! */ 496 ret = 0; 497 goto out; 498 } 499 500 method = ssh_userauth_list(s->session, NULL); 501 trace_ssh_auth_methods(method); 502 503 /* 504 * Try to authenticate with publickey, using the ssh-agent 505 * if available. 506 */ 507 if (method & SSH_AUTH_METHOD_PUBLICKEY) { 508 r = ssh_userauth_publickey_auto(s->session, NULL, NULL); 509 if (r == SSH_AUTH_ERROR) { 510 ret = -EINVAL; 511 session_error_setg(errp, s, "failed to authenticate using " 512 "publickey authentication"); 513 goto out; 514 } else if (r == SSH_AUTH_SUCCESS) { 515 /* Authenticated! */ 516 ret = 0; 517 goto out; 518 } 519 } 520 521 ret = -EPERM; 522 error_setg(errp, "failed to authenticate using publickey authentication " 523 "and the identities held by your ssh-agent"); 524 525 out: 526 return ret; 527 } 528 529 static QemuOptsList ssh_runtime_opts = { 530 .name = "ssh", 531 .head = QTAILQ_HEAD_INITIALIZER(ssh_runtime_opts.head), 532 .desc = { 533 { 534 .name = "host", 535 .type = QEMU_OPT_STRING, 536 .help = "Host to connect to", 537 }, 538 { 539 .name = "port", 540 .type = QEMU_OPT_NUMBER, 541 .help = "Port to connect to", 542 }, 543 { 544 .name = "host_key_check", 545 .type = QEMU_OPT_STRING, 546 .help = "Defines how and what to check the host key against", 547 }, 548 { /* end of list */ } 549 }, 550 }; 551 552 static bool ssh_process_legacy_options(QDict *output_opts, 553 QemuOpts *legacy_opts, 554 Error **errp) 555 { 556 const char *host = qemu_opt_get(legacy_opts, "host"); 557 const char *port = qemu_opt_get(legacy_opts, "port"); 558 const char *host_key_check = qemu_opt_get(legacy_opts, "host_key_check"); 559 560 if (!host && port) { 561 error_setg(errp, "port may not be used without host"); 562 return false; 563 } 564 565 if (host) { 566 qdict_put_str(output_opts, "server.host", host); 567 qdict_put_str(output_opts, "server.port", port ?: stringify(22)); 568 } 569 570 if (host_key_check) { 571 if (strcmp(host_key_check, "no") == 0) { 572 qdict_put_str(output_opts, "host-key-check.mode", "none"); 573 } else if (strncmp(host_key_check, "md5:", 4) == 0) { 574 qdict_put_str(output_opts, "host-key-check.mode", "hash"); 575 qdict_put_str(output_opts, "host-key-check.type", "md5"); 576 qdict_put_str(output_opts, "host-key-check.hash", 577 &host_key_check[4]); 578 } else if (strncmp(host_key_check, "sha1:", 5) == 0) { 579 qdict_put_str(output_opts, "host-key-check.mode", "hash"); 580 qdict_put_str(output_opts, "host-key-check.type", "sha1"); 581 qdict_put_str(output_opts, "host-key-check.hash", 582 &host_key_check[5]); 583 } else if (strncmp(host_key_check, "sha256:", 7) == 0) { 584 qdict_put_str(output_opts, "host-key-check.mode", "hash"); 585 qdict_put_str(output_opts, "host-key-check.type", "sha256"); 586 qdict_put_str(output_opts, "host-key-check.hash", 587 &host_key_check[7]); 588 } else if (strcmp(host_key_check, "yes") == 0) { 589 qdict_put_str(output_opts, "host-key-check.mode", "known_hosts"); 590 } else { 591 error_setg(errp, "unknown host_key_check setting (%s)", 592 host_key_check); 593 return false; 594 } 595 } 596 597 return true; 598 } 599 600 static BlockdevOptionsSsh *ssh_parse_options(QDict *options, Error **errp) 601 { 602 BlockdevOptionsSsh *result = NULL; 603 QemuOpts *opts = NULL; 604 const QDictEntry *e; 605 Visitor *v; 606 607 /* Translate legacy options */ 608 opts = qemu_opts_create(&ssh_runtime_opts, NULL, 0, &error_abort); 609 if (!qemu_opts_absorb_qdict(opts, options, errp)) { 610 goto fail; 611 } 612 613 if (!ssh_process_legacy_options(options, opts, errp)) { 614 goto fail; 615 } 616 617 /* Create the QAPI object */ 618 v = qobject_input_visitor_new_flat_confused(options, errp); 619 if (!v) { 620 goto fail; 621 } 622 623 visit_type_BlockdevOptionsSsh(v, NULL, &result, errp); 624 visit_free(v); 625 if (!result) { 626 goto fail; 627 } 628 629 /* Remove the processed options from the QDict (the visitor processes 630 * _all_ options in the QDict) */ 631 while ((e = qdict_first(options))) { 632 qdict_del(options, e->key); 633 } 634 635 fail: 636 qemu_opts_del(opts); 637 return result; 638 } 639 640 static int connect_to_ssh(BDRVSSHState *s, BlockdevOptionsSsh *opts, 641 int ssh_flags, int creat_mode, Error **errp) 642 { 643 int r, ret; 644 unsigned int port = 0; 645 int new_sock = -1; 646 647 if (opts->user) { 648 s->user = g_strdup(opts->user); 649 } else { 650 s->user = g_strdup(g_get_user_name()); 651 if (!s->user) { 652 error_setg_errno(errp, errno, "Can't get user name"); 653 ret = -errno; 654 goto err; 655 } 656 } 657 658 /* Pop the config into our state object, Exit if invalid */ 659 s->inet = opts->server; 660 opts->server = NULL; 661 662 if (qemu_strtoui(s->inet->port, NULL, 10, &port) < 0) { 663 error_setg(errp, "Use only numeric port value"); 664 ret = -EINVAL; 665 goto err; 666 } 667 668 /* Open the socket and connect. */ 669 new_sock = inet_connect_saddr(s->inet, errp); 670 if (new_sock < 0) { 671 ret = -EIO; 672 goto err; 673 } 674 675 /* 676 * Try to disable the Nagle algorithm on TCP sockets to reduce latency, 677 * but do not fail if it cannot be disabled. 678 */ 679 r = socket_set_nodelay(new_sock); 680 if (r < 0) { 681 warn_report("can't set TCP_NODELAY for the ssh server %s: %s", 682 s->inet->host, strerror(errno)); 683 } 684 685 /* Create SSH session. */ 686 s->session = ssh_new(); 687 if (!s->session) { 688 ret = -EINVAL; 689 session_error_setg(errp, s, "failed to initialize libssh session"); 690 goto err; 691 } 692 693 /* 694 * Make sure we are in blocking mode during the connection and 695 * authentication phases. 696 */ 697 ssh_set_blocking(s->session, 1); 698 699 r = ssh_options_set(s->session, SSH_OPTIONS_USER, s->user); 700 if (r < 0) { 701 ret = -EINVAL; 702 session_error_setg(errp, s, 703 "failed to set the user in the libssh session"); 704 goto err; 705 } 706 707 r = ssh_options_set(s->session, SSH_OPTIONS_HOST, s->inet->host); 708 if (r < 0) { 709 ret = -EINVAL; 710 session_error_setg(errp, s, 711 "failed to set the host in the libssh session"); 712 goto err; 713 } 714 715 if (port > 0) { 716 r = ssh_options_set(s->session, SSH_OPTIONS_PORT, &port); 717 if (r < 0) { 718 ret = -EINVAL; 719 session_error_setg(errp, s, 720 "failed to set the port in the libssh session"); 721 goto err; 722 } 723 } 724 725 r = ssh_options_set(s->session, SSH_OPTIONS_COMPRESSION, "none"); 726 if (r < 0) { 727 ret = -EINVAL; 728 session_error_setg(errp, s, 729 "failed to disable the compression in the libssh " 730 "session"); 731 goto err; 732 } 733 734 /* Read ~/.ssh/config. */ 735 r = ssh_options_parse_config(s->session, NULL); 736 if (r < 0) { 737 ret = -EINVAL; 738 session_error_setg(errp, s, "failed to parse ~/.ssh/config"); 739 goto err; 740 } 741 742 r = ssh_options_set(s->session, SSH_OPTIONS_FD, &new_sock); 743 if (r < 0) { 744 ret = -EINVAL; 745 session_error_setg(errp, s, 746 "failed to set the socket in the libssh session"); 747 goto err; 748 } 749 /* libssh took ownership of the socket. */ 750 s->sock = new_sock; 751 new_sock = -1; 752 753 /* Connect. */ 754 r = ssh_connect(s->session); 755 if (r != SSH_OK) { 756 ret = -EINVAL; 757 session_error_setg(errp, s, "failed to establish SSH session"); 758 goto err; 759 } 760 761 /* Check the remote host's key against known_hosts. */ 762 ret = check_host_key(s, opts->host_key_check, errp); 763 if (ret < 0) { 764 goto err; 765 } 766 767 /* Authenticate. */ 768 ret = authenticate(s, errp); 769 if (ret < 0) { 770 goto err; 771 } 772 773 /* Start SFTP. */ 774 s->sftp = sftp_new(s->session); 775 if (!s->sftp) { 776 session_error_setg(errp, s, "failed to create sftp handle"); 777 ret = -EINVAL; 778 goto err; 779 } 780 781 r = sftp_init(s->sftp); 782 if (r < 0) { 783 sftp_error_setg(errp, s, "failed to initialize sftp handle"); 784 ret = -EINVAL; 785 goto err; 786 } 787 788 /* Open the remote file. */ 789 trace_ssh_connect_to_ssh(opts->path, ssh_flags, creat_mode); 790 s->sftp_handle = sftp_open(s->sftp, opts->path, ssh_flags, creat_mode); 791 if (!s->sftp_handle) { 792 sftp_error_setg(errp, s, "failed to open remote file '%s'", 793 opts->path); 794 ret = -EINVAL; 795 goto err; 796 } 797 798 /* Make sure the SFTP file is handled in blocking mode. */ 799 sftp_file_set_blocking(s->sftp_handle); 800 801 s->attrs = sftp_fstat(s->sftp_handle); 802 if (!s->attrs) { 803 sftp_error_setg(errp, s, "failed to read file attributes"); 804 return -EINVAL; 805 } 806 807 return 0; 808 809 err: 810 if (s->attrs) { 811 sftp_attributes_free(s->attrs); 812 } 813 s->attrs = NULL; 814 if (s->sftp_handle) { 815 sftp_close(s->sftp_handle); 816 } 817 s->sftp_handle = NULL; 818 if (s->sftp) { 819 sftp_free(s->sftp); 820 } 821 s->sftp = NULL; 822 if (s->session) { 823 ssh_disconnect(s->session); 824 ssh_free(s->session); 825 } 826 s->session = NULL; 827 s->sock = -1; 828 if (new_sock >= 0) { 829 close(new_sock); 830 } 831 832 return ret; 833 } 834 835 static int ssh_file_open(BlockDriverState *bs, QDict *options, int bdrv_flags, 836 Error **errp) 837 { 838 BDRVSSHState *s = bs->opaque; 839 BlockdevOptionsSsh *opts; 840 int ret; 841 int ssh_flags; 842 843 ssh_state_init(s); 844 845 ssh_flags = 0; 846 if (bdrv_flags & BDRV_O_RDWR) { 847 ssh_flags |= O_RDWR; 848 } else { 849 ssh_flags |= O_RDONLY; 850 } 851 852 opts = ssh_parse_options(options, errp); 853 if (opts == NULL) { 854 return -EINVAL; 855 } 856 857 /* Start up SSH. */ 858 ret = connect_to_ssh(s, opts, ssh_flags, 0, errp); 859 if (ret < 0) { 860 goto err; 861 } 862 863 /* Go non-blocking. */ 864 ssh_set_blocking(s->session, 0); 865 866 if (s->attrs->type == SSH_FILEXFER_TYPE_REGULAR) { 867 bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE; 868 } 869 870 qapi_free_BlockdevOptionsSsh(opts); 871 872 return 0; 873 874 err: 875 qapi_free_BlockdevOptionsSsh(opts); 876 877 return ret; 878 } 879 880 /* Note: This is a blocking operation */ 881 static int ssh_grow_file(BDRVSSHState *s, int64_t offset, Error **errp) 882 { 883 ssize_t ret; 884 char c[1] = { '\0' }; 885 int was_blocking = ssh_is_blocking(s->session); 886 887 /* offset must be strictly greater than the current size so we do 888 * not overwrite anything */ 889 assert(offset > 0 && offset > s->attrs->size); 890 891 ssh_set_blocking(s->session, 1); 892 893 sftp_seek64(s->sftp_handle, offset - 1); 894 ret = sftp_write(s->sftp_handle, c, 1); 895 896 ssh_set_blocking(s->session, was_blocking); 897 898 if (ret < 0) { 899 sftp_error_setg(errp, s, "Failed to grow file"); 900 return -EIO; 901 } 902 903 s->attrs->size = offset; 904 return 0; 905 } 906 907 static QemuOptsList ssh_create_opts = { 908 .name = "ssh-create-opts", 909 .head = QTAILQ_HEAD_INITIALIZER(ssh_create_opts.head), 910 .desc = { 911 { 912 .name = BLOCK_OPT_SIZE, 913 .type = QEMU_OPT_SIZE, 914 .help = "Virtual disk size" 915 }, 916 { /* end of list */ } 917 } 918 }; 919 920 static int ssh_co_create(BlockdevCreateOptions *options, Error **errp) 921 { 922 BlockdevCreateOptionsSsh *opts = &options->u.ssh; 923 BDRVSSHState s; 924 int ret; 925 926 assert(options->driver == BLOCKDEV_DRIVER_SSH); 927 928 ssh_state_init(&s); 929 930 ret = connect_to_ssh(&s, opts->location, 931 O_RDWR | O_CREAT | O_TRUNC, 932 0644, errp); 933 if (ret < 0) { 934 goto fail; 935 } 936 937 if (opts->size > 0) { 938 ret = ssh_grow_file(&s, opts->size, errp); 939 if (ret < 0) { 940 goto fail; 941 } 942 } 943 944 ret = 0; 945 fail: 946 ssh_state_free(&s); 947 return ret; 948 } 949 950 static int coroutine_fn ssh_co_create_opts(BlockDriver *drv, 951 const char *filename, 952 QemuOpts *opts, 953 Error **errp) 954 { 955 BlockdevCreateOptions *create_options; 956 BlockdevCreateOptionsSsh *ssh_opts; 957 int ret; 958 QDict *uri_options = NULL; 959 960 create_options = g_new0(BlockdevCreateOptions, 1); 961 create_options->driver = BLOCKDEV_DRIVER_SSH; 962 ssh_opts = &create_options->u.ssh; 963 964 /* Get desired file size. */ 965 ssh_opts->size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0), 966 BDRV_SECTOR_SIZE); 967 trace_ssh_co_create_opts(ssh_opts->size); 968 969 uri_options = qdict_new(); 970 ret = parse_uri(filename, uri_options, errp); 971 if (ret < 0) { 972 goto out; 973 } 974 975 ssh_opts->location = ssh_parse_options(uri_options, errp); 976 if (ssh_opts->location == NULL) { 977 ret = -EINVAL; 978 goto out; 979 } 980 981 ret = ssh_co_create(create_options, errp); 982 983 out: 984 qobject_unref(uri_options); 985 qapi_free_BlockdevCreateOptions(create_options); 986 return ret; 987 } 988 989 static void ssh_close(BlockDriverState *bs) 990 { 991 BDRVSSHState *s = bs->opaque; 992 993 ssh_state_free(s); 994 } 995 996 static int ssh_has_zero_init(BlockDriverState *bs) 997 { 998 BDRVSSHState *s = bs->opaque; 999 /* Assume false, unless we can positively prove it's true. */ 1000 int has_zero_init = 0; 1001 1002 if (s->attrs->type == SSH_FILEXFER_TYPE_REGULAR) { 1003 has_zero_init = 1; 1004 } 1005 1006 return has_zero_init; 1007 } 1008 1009 typedef struct BDRVSSHRestart { 1010 BlockDriverState *bs; 1011 Coroutine *co; 1012 } BDRVSSHRestart; 1013 1014 static void restart_coroutine(void *opaque) 1015 { 1016 BDRVSSHRestart *restart = opaque; 1017 BlockDriverState *bs = restart->bs; 1018 BDRVSSHState *s = bs->opaque; 1019 AioContext *ctx = bdrv_get_aio_context(bs); 1020 1021 trace_ssh_restart_coroutine(restart->co); 1022 aio_set_fd_handler(ctx, s->sock, NULL, NULL, NULL, NULL, NULL); 1023 1024 aio_co_wake(restart->co); 1025 } 1026 1027 /* A non-blocking call returned EAGAIN, so yield, ensuring the 1028 * handlers are set up so that we'll be rescheduled when there is an 1029 * interesting event on the socket. 1030 */ 1031 static coroutine_fn void co_yield(BDRVSSHState *s, BlockDriverState *bs) 1032 { 1033 int r; 1034 IOHandler *rd_handler = NULL, *wr_handler = NULL; 1035 BDRVSSHRestart restart = { 1036 .bs = bs, 1037 .co = qemu_coroutine_self() 1038 }; 1039 1040 r = ssh_get_poll_flags(s->session); 1041 1042 if (r & SSH_READ_PENDING) { 1043 rd_handler = restart_coroutine; 1044 } 1045 if (r & SSH_WRITE_PENDING) { 1046 wr_handler = restart_coroutine; 1047 } 1048 1049 trace_ssh_co_yield(s->sock, rd_handler, wr_handler); 1050 1051 aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock, 1052 rd_handler, wr_handler, NULL, NULL, &restart); 1053 qemu_coroutine_yield(); 1054 trace_ssh_co_yield_back(s->sock); 1055 } 1056 1057 static coroutine_fn int ssh_read(BDRVSSHState *s, BlockDriverState *bs, 1058 int64_t offset, size_t size, 1059 QEMUIOVector *qiov) 1060 { 1061 ssize_t r; 1062 size_t got; 1063 char *buf, *end_of_vec; 1064 struct iovec *i; 1065 1066 trace_ssh_read(offset, size); 1067 1068 trace_ssh_seek(offset); 1069 sftp_seek64(s->sftp_handle, offset); 1070 1071 /* This keeps track of the current iovec element ('i'), where we 1072 * will write to next ('buf'), and the end of the current iovec 1073 * ('end_of_vec'). 1074 */ 1075 i = &qiov->iov[0]; 1076 buf = i->iov_base; 1077 end_of_vec = i->iov_base + i->iov_len; 1078 1079 for (got = 0; got < size; ) { 1080 size_t request_read_size; 1081 again: 1082 /* 1083 * The size of SFTP packets is limited to 32K bytes, so limit 1084 * the amount of data requested to 16K, as libssh currently 1085 * does not handle multiple requests on its own. 1086 */ 1087 request_read_size = MIN(end_of_vec - buf, 16384); 1088 trace_ssh_read_buf(buf, end_of_vec - buf, request_read_size); 1089 r = sftp_read(s->sftp_handle, buf, request_read_size); 1090 trace_ssh_read_return(r, sftp_get_error(s->sftp)); 1091 1092 if (r == SSH_AGAIN) { 1093 co_yield(s, bs); 1094 goto again; 1095 } 1096 if (r == SSH_EOF || (r == 0 && sftp_get_error(s->sftp) == SSH_FX_EOF)) { 1097 /* EOF: Short read so pad the buffer with zeroes and return it. */ 1098 qemu_iovec_memset(qiov, got, 0, size - got); 1099 return 0; 1100 } 1101 if (r <= 0) { 1102 sftp_error_trace(s, "read"); 1103 return -EIO; 1104 } 1105 1106 got += r; 1107 buf += r; 1108 if (buf >= end_of_vec && got < size) { 1109 i++; 1110 buf = i->iov_base; 1111 end_of_vec = i->iov_base + i->iov_len; 1112 } 1113 } 1114 1115 return 0; 1116 } 1117 1118 static coroutine_fn int ssh_co_readv(BlockDriverState *bs, 1119 int64_t sector_num, 1120 int nb_sectors, QEMUIOVector *qiov) 1121 { 1122 BDRVSSHState *s = bs->opaque; 1123 int ret; 1124 1125 qemu_co_mutex_lock(&s->lock); 1126 ret = ssh_read(s, bs, sector_num * BDRV_SECTOR_SIZE, 1127 nb_sectors * BDRV_SECTOR_SIZE, qiov); 1128 qemu_co_mutex_unlock(&s->lock); 1129 1130 return ret; 1131 } 1132 1133 static coroutine_fn int ssh_write(BDRVSSHState *s, BlockDriverState *bs, 1134 int64_t offset, size_t size, 1135 QEMUIOVector *qiov) 1136 { 1137 ssize_t r; 1138 size_t written; 1139 char *buf, *end_of_vec; 1140 struct iovec *i; 1141 1142 trace_ssh_write(offset, size); 1143 1144 trace_ssh_seek(offset); 1145 sftp_seek64(s->sftp_handle, offset); 1146 1147 /* This keeps track of the current iovec element ('i'), where we 1148 * will read from next ('buf'), and the end of the current iovec 1149 * ('end_of_vec'). 1150 */ 1151 i = &qiov->iov[0]; 1152 buf = i->iov_base; 1153 end_of_vec = i->iov_base + i->iov_len; 1154 1155 for (written = 0; written < size; ) { 1156 size_t request_write_size; 1157 again: 1158 /* 1159 * Avoid too large data packets, as libssh currently does not 1160 * handle multiple requests on its own. 1161 */ 1162 request_write_size = MIN(end_of_vec - buf, 131072); 1163 trace_ssh_write_buf(buf, end_of_vec - buf, request_write_size); 1164 r = sftp_write(s->sftp_handle, buf, request_write_size); 1165 trace_ssh_write_return(r, sftp_get_error(s->sftp)); 1166 1167 if (r == SSH_AGAIN) { 1168 co_yield(s, bs); 1169 goto again; 1170 } 1171 if (r < 0) { 1172 sftp_error_trace(s, "write"); 1173 return -EIO; 1174 } 1175 1176 written += r; 1177 buf += r; 1178 if (buf >= end_of_vec && written < size) { 1179 i++; 1180 buf = i->iov_base; 1181 end_of_vec = i->iov_base + i->iov_len; 1182 } 1183 1184 if (offset + written > s->attrs->size) { 1185 s->attrs->size = offset + written; 1186 } 1187 } 1188 1189 return 0; 1190 } 1191 1192 static coroutine_fn int ssh_co_writev(BlockDriverState *bs, 1193 int64_t sector_num, 1194 int nb_sectors, QEMUIOVector *qiov, 1195 int flags) 1196 { 1197 BDRVSSHState *s = bs->opaque; 1198 int ret; 1199 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 coroutine_fn ssh_co_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_co_getlength = ssh_co_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