Richard W.M. Jones | 0a12ec8 | 2013-04-09 15:30:53 +0100 | [diff] [blame^] | 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 <stdio.h> |
| 26 | #include <stdlib.h> |
| 27 | #include <stdarg.h> |
| 28 | |
| 29 | #include <libssh2.h> |
| 30 | #include <libssh2_sftp.h> |
| 31 | |
| 32 | #include "block/block_int.h" |
| 33 | #include "qemu/sockets.h" |
| 34 | #include "qemu/uri.h" |
| 35 | #include "qapi/qmp/qint.h" |
| 36 | |
| 37 | /* DEBUG_SSH=1 enables the DPRINTF (debugging printf) statements in |
| 38 | * this block driver code. |
| 39 | * |
| 40 | * TRACE_LIBSSH2=<bitmask> enables tracing in libssh2 itself. Note |
| 41 | * that this requires that libssh2 was specially compiled with the |
| 42 | * `./configure --enable-debug' option, so most likely you will have |
| 43 | * to compile it yourself. The meaning of <bitmask> is described |
| 44 | * here: http://www.libssh2.org/libssh2_trace.html |
| 45 | */ |
| 46 | #define DEBUG_SSH 0 |
| 47 | #define TRACE_LIBSSH2 0 /* or try: LIBSSH2_TRACE_SFTP */ |
| 48 | |
| 49 | #define DPRINTF(fmt, ...) \ |
| 50 | do { \ |
| 51 | if (DEBUG_SSH) { \ |
| 52 | fprintf(stderr, "ssh: %-15s " fmt "\n", \ |
| 53 | __func__, ##__VA_ARGS__); \ |
| 54 | } \ |
| 55 | } while (0) |
| 56 | |
| 57 | typedef struct BDRVSSHState { |
| 58 | /* Coroutine. */ |
| 59 | CoMutex lock; |
| 60 | |
| 61 | /* SSH connection. */ |
| 62 | int sock; /* socket */ |
| 63 | LIBSSH2_SESSION *session; /* ssh session */ |
| 64 | LIBSSH2_SFTP *sftp; /* sftp session */ |
| 65 | LIBSSH2_SFTP_HANDLE *sftp_handle; /* sftp remote file handle */ |
| 66 | |
| 67 | /* See ssh_seek() function below. */ |
| 68 | int64_t offset; |
| 69 | bool offset_op_read; |
| 70 | |
| 71 | /* File attributes at open. We try to keep the .filesize field |
| 72 | * updated if it changes (eg by writing at the end of the file). |
| 73 | */ |
| 74 | LIBSSH2_SFTP_ATTRIBUTES attrs; |
| 75 | } BDRVSSHState; |
| 76 | |
| 77 | static void ssh_state_init(BDRVSSHState *s) |
| 78 | { |
| 79 | memset(s, 0, sizeof *s); |
| 80 | s->sock = -1; |
| 81 | s->offset = -1; |
| 82 | qemu_co_mutex_init(&s->lock); |
| 83 | } |
| 84 | |
| 85 | static void ssh_state_free(BDRVSSHState *s) |
| 86 | { |
| 87 | if (s->sftp_handle) { |
| 88 | libssh2_sftp_close(s->sftp_handle); |
| 89 | } |
| 90 | if (s->sftp) { |
| 91 | libssh2_sftp_shutdown(s->sftp); |
| 92 | } |
| 93 | if (s->session) { |
| 94 | libssh2_session_disconnect(s->session, |
| 95 | "from qemu ssh client: " |
| 96 | "user closed the connection"); |
| 97 | libssh2_session_free(s->session); |
| 98 | } |
| 99 | if (s->sock >= 0) { |
| 100 | close(s->sock); |
| 101 | } |
| 102 | } |
| 103 | |
| 104 | /* Wrappers around error_report which make sure to dump as much |
| 105 | * information from libssh2 as possible. |
| 106 | */ |
| 107 | static void |
| 108 | session_error_report(BDRVSSHState *s, const char *fs, ...) |
| 109 | { |
| 110 | va_list args; |
| 111 | |
| 112 | va_start(args, fs); |
| 113 | error_vprintf(fs, args); |
| 114 | |
| 115 | if ((s)->session) { |
| 116 | char *ssh_err; |
| 117 | int ssh_err_code; |
| 118 | |
| 119 | libssh2_session_last_error((s)->session, &ssh_err, NULL, 0); |
| 120 | /* This is not an errno. See <libssh2.h>. */ |
| 121 | ssh_err_code = libssh2_session_last_errno((s)->session); |
| 122 | |
| 123 | error_printf(": %s (libssh2 error code: %d)", ssh_err, ssh_err_code); |
| 124 | } |
| 125 | |
| 126 | va_end(args); |
| 127 | error_printf("\n"); |
| 128 | } |
| 129 | |
| 130 | static void |
| 131 | sftp_error_report(BDRVSSHState *s, const char *fs, ...) |
| 132 | { |
| 133 | va_list args; |
| 134 | |
| 135 | va_start(args, fs); |
| 136 | error_vprintf(fs, args); |
| 137 | |
| 138 | if ((s)->sftp) { |
| 139 | char *ssh_err; |
| 140 | int ssh_err_code; |
| 141 | unsigned long sftp_err_code; |
| 142 | |
| 143 | libssh2_session_last_error((s)->session, &ssh_err, NULL, 0); |
| 144 | /* This is not an errno. See <libssh2.h>. */ |
| 145 | ssh_err_code = libssh2_session_last_errno((s)->session); |
| 146 | /* See <libssh2_sftp.h>. */ |
| 147 | sftp_err_code = libssh2_sftp_last_error((s)->sftp); |
| 148 | |
| 149 | error_printf(": %s (libssh2 error code: %d, sftp error code: %lu)", |
| 150 | ssh_err, ssh_err_code, sftp_err_code); |
| 151 | } |
| 152 | |
| 153 | va_end(args); |
| 154 | error_printf("\n"); |
| 155 | } |
| 156 | |
| 157 | static int parse_uri(const char *filename, QDict *options, Error **errp) |
| 158 | { |
| 159 | URI *uri = NULL; |
| 160 | QueryParams *qp = NULL; |
| 161 | int i; |
| 162 | |
| 163 | uri = uri_parse(filename); |
| 164 | if (!uri) { |
| 165 | return -EINVAL; |
| 166 | } |
| 167 | |
| 168 | if (strcmp(uri->scheme, "ssh") != 0) { |
| 169 | error_setg(errp, "URI scheme must be 'ssh'"); |
| 170 | goto err; |
| 171 | } |
| 172 | |
| 173 | if (!uri->server || strcmp(uri->server, "") == 0) { |
| 174 | error_setg(errp, "missing hostname in URI"); |
| 175 | goto err; |
| 176 | } |
| 177 | |
| 178 | if (!uri->path || strcmp(uri->path, "") == 0) { |
| 179 | error_setg(errp, "missing remote path in URI"); |
| 180 | goto err; |
| 181 | } |
| 182 | |
| 183 | qp = query_params_parse(uri->query); |
| 184 | if (!qp) { |
| 185 | error_setg(errp, "could not parse query parameters"); |
| 186 | goto err; |
| 187 | } |
| 188 | |
| 189 | if(uri->user && strcmp(uri->user, "") != 0) { |
| 190 | qdict_put(options, "user", qstring_from_str(uri->user)); |
| 191 | } |
| 192 | |
| 193 | qdict_put(options, "host", qstring_from_str(uri->server)); |
| 194 | |
| 195 | if (uri->port) { |
| 196 | qdict_put(options, "port", qint_from_int(uri->port)); |
| 197 | } |
| 198 | |
| 199 | qdict_put(options, "path", qstring_from_str(uri->path)); |
| 200 | |
| 201 | /* Pick out any query parameters that we understand, and ignore |
| 202 | * the rest. |
| 203 | */ |
| 204 | for (i = 0; i < qp->n; ++i) { |
| 205 | if (strcmp(qp->p[i].name, "host_key_check") == 0) { |
| 206 | qdict_put(options, "host_key_check", |
| 207 | qstring_from_str(qp->p[i].value)); |
| 208 | } |
| 209 | } |
| 210 | |
| 211 | query_params_free(qp); |
| 212 | uri_free(uri); |
| 213 | return 0; |
| 214 | |
| 215 | err: |
| 216 | if (qp) { |
| 217 | query_params_free(qp); |
| 218 | } |
| 219 | if (uri) { |
| 220 | uri_free(uri); |
| 221 | } |
| 222 | return -EINVAL; |
| 223 | } |
| 224 | |
| 225 | static void ssh_parse_filename(const char *filename, QDict *options, |
| 226 | Error **errp) |
| 227 | { |
| 228 | if (qdict_haskey(options, "user") || |
| 229 | qdict_haskey(options, "host") || |
| 230 | qdict_haskey(options, "port") || |
| 231 | qdict_haskey(options, "path") || |
| 232 | qdict_haskey(options, "host_key_check")) { |
| 233 | error_setg(errp, "user, host, port, path, host_key_check cannot be used at the same time as a file option"); |
| 234 | return; |
| 235 | } |
| 236 | |
| 237 | parse_uri(filename, options, errp); |
| 238 | } |
| 239 | |
| 240 | static int check_host_key_knownhosts(BDRVSSHState *s, |
| 241 | const char *host, int port) |
| 242 | { |
| 243 | const char *home; |
| 244 | char *knh_file = NULL; |
| 245 | LIBSSH2_KNOWNHOSTS *knh = NULL; |
| 246 | struct libssh2_knownhost *found; |
| 247 | int ret, r; |
| 248 | const char *hostkey; |
| 249 | size_t len; |
| 250 | int type; |
| 251 | |
| 252 | hostkey = libssh2_session_hostkey(s->session, &len, &type); |
| 253 | if (!hostkey) { |
| 254 | ret = -EINVAL; |
| 255 | session_error_report(s, "failed to read remote host key"); |
| 256 | goto out; |
| 257 | } |
| 258 | |
| 259 | knh = libssh2_knownhost_init(s->session); |
| 260 | if (!knh) { |
| 261 | ret = -EINVAL; |
| 262 | session_error_report(s, "failed to initialize known hosts support"); |
| 263 | goto out; |
| 264 | } |
| 265 | |
| 266 | home = getenv("HOME"); |
| 267 | if (home) { |
| 268 | knh_file = g_strdup_printf("%s/.ssh/known_hosts", home); |
| 269 | } else { |
| 270 | knh_file = g_strdup_printf("/root/.ssh/known_hosts"); |
| 271 | } |
| 272 | |
| 273 | /* Read all known hosts from OpenSSH-style known_hosts file. */ |
| 274 | libssh2_knownhost_readfile(knh, knh_file, LIBSSH2_KNOWNHOST_FILE_OPENSSH); |
| 275 | |
| 276 | r = libssh2_knownhost_checkp(knh, host, port, hostkey, len, |
| 277 | LIBSSH2_KNOWNHOST_TYPE_PLAIN| |
| 278 | LIBSSH2_KNOWNHOST_KEYENC_RAW, |
| 279 | &found); |
| 280 | switch (r) { |
| 281 | case LIBSSH2_KNOWNHOST_CHECK_MATCH: |
| 282 | /* OK */ |
| 283 | DPRINTF("host key OK: %s", found->key); |
| 284 | break; |
| 285 | case LIBSSH2_KNOWNHOST_CHECK_MISMATCH: |
| 286 | ret = -EINVAL; |
| 287 | session_error_report(s, "host key does not match the one in known_hosts (found key %s)", |
| 288 | found->key); |
| 289 | goto out; |
| 290 | case LIBSSH2_KNOWNHOST_CHECK_NOTFOUND: |
| 291 | ret = -EINVAL; |
| 292 | session_error_report(s, "no host key was found in known_hosts"); |
| 293 | goto out; |
| 294 | case LIBSSH2_KNOWNHOST_CHECK_FAILURE: |
| 295 | ret = -EINVAL; |
| 296 | session_error_report(s, "failure matching the host key with known_hosts"); |
| 297 | goto out; |
| 298 | default: |
| 299 | ret = -EINVAL; |
| 300 | session_error_report(s, "unknown error matching the host key with known_hosts (%d)", |
| 301 | r); |
| 302 | goto out; |
| 303 | } |
| 304 | |
| 305 | /* known_hosts checking successful. */ |
| 306 | ret = 0; |
| 307 | |
| 308 | out: |
| 309 | if (knh != NULL) { |
| 310 | libssh2_knownhost_free(knh); |
| 311 | } |
| 312 | g_free(knh_file); |
| 313 | return ret; |
| 314 | } |
| 315 | |
| 316 | static unsigned hex2decimal(char ch) |
| 317 | { |
| 318 | if (ch >= '0' && ch <= '9') { |
| 319 | return (ch - '0'); |
| 320 | } else if (ch >= 'a' && ch <= 'f') { |
| 321 | return 10 + (ch - 'a'); |
| 322 | } else if (ch >= 'A' && ch <= 'F') { |
| 323 | return 10 + (ch - 'A'); |
| 324 | } |
| 325 | |
| 326 | return -1; |
| 327 | } |
| 328 | |
| 329 | /* Compare the binary fingerprint (hash of host key) with the |
| 330 | * host_key_check parameter. |
| 331 | */ |
| 332 | static int compare_fingerprint(const unsigned char *fingerprint, size_t len, |
| 333 | const char *host_key_check) |
| 334 | { |
| 335 | unsigned c; |
| 336 | |
| 337 | while (len > 0) { |
| 338 | while (*host_key_check == ':') |
| 339 | host_key_check++; |
| 340 | if (!qemu_isxdigit(host_key_check[0]) || |
| 341 | !qemu_isxdigit(host_key_check[1])) |
| 342 | return 1; |
| 343 | c = hex2decimal(host_key_check[0]) * 16 + |
| 344 | hex2decimal(host_key_check[1]); |
| 345 | if (c - *fingerprint != 0) |
| 346 | return c - *fingerprint; |
| 347 | fingerprint++; |
| 348 | len--; |
| 349 | host_key_check += 2; |
| 350 | } |
| 351 | return *host_key_check - '\0'; |
| 352 | } |
| 353 | |
| 354 | static int |
| 355 | check_host_key_hash(BDRVSSHState *s, const char *hash, |
| 356 | int hash_type, size_t fingerprint_len) |
| 357 | { |
| 358 | const char *fingerprint; |
| 359 | |
| 360 | fingerprint = libssh2_hostkey_hash(s->session, hash_type); |
| 361 | if (!fingerprint) { |
| 362 | session_error_report(s, "failed to read remote host key"); |
| 363 | return -EINVAL; |
| 364 | } |
| 365 | |
| 366 | if(compare_fingerprint((unsigned char *) fingerprint, fingerprint_len, |
| 367 | hash) != 0) { |
| 368 | error_report("remote host key does not match host_key_check '%s'", |
| 369 | hash); |
| 370 | return -EPERM; |
| 371 | } |
| 372 | |
| 373 | return 0; |
| 374 | } |
| 375 | |
| 376 | static int check_host_key(BDRVSSHState *s, const char *host, int port, |
| 377 | const char *host_key_check) |
| 378 | { |
| 379 | /* host_key_check=no */ |
| 380 | if (strcmp(host_key_check, "no") == 0) { |
| 381 | return 0; |
| 382 | } |
| 383 | |
| 384 | /* host_key_check=md5:xx:yy:zz:... */ |
| 385 | if (strlen(host_key_check) >= 4 && |
| 386 | strncmp(host_key_check, "md5:", 4) == 0) { |
| 387 | return check_host_key_hash(s, &host_key_check[4], |
| 388 | LIBSSH2_HOSTKEY_HASH_MD5, 16); |
| 389 | } |
| 390 | |
| 391 | /* host_key_check=sha1:xx:yy:zz:... */ |
| 392 | if (strlen(host_key_check) >= 5 && |
| 393 | strncmp(host_key_check, "sha1:", 5) == 0) { |
| 394 | return check_host_key_hash(s, &host_key_check[5], |
| 395 | LIBSSH2_HOSTKEY_HASH_SHA1, 20); |
| 396 | } |
| 397 | |
| 398 | /* host_key_check=yes */ |
| 399 | if (strcmp(host_key_check, "yes") == 0) { |
| 400 | return check_host_key_knownhosts(s, host, port); |
| 401 | } |
| 402 | |
| 403 | error_report("unknown host_key_check setting (%s)", host_key_check); |
| 404 | return -EINVAL; |
| 405 | } |
| 406 | |
| 407 | static int authenticate(BDRVSSHState *s, const char *user) |
| 408 | { |
| 409 | int r, ret; |
| 410 | const char *userauthlist; |
| 411 | LIBSSH2_AGENT *agent = NULL; |
| 412 | struct libssh2_agent_publickey *identity; |
| 413 | struct libssh2_agent_publickey *prev_identity = NULL; |
| 414 | |
| 415 | userauthlist = libssh2_userauth_list(s->session, user, strlen(user)); |
| 416 | if (strstr(userauthlist, "publickey") == NULL) { |
| 417 | ret = -EPERM; |
| 418 | error_report("remote server does not support \"publickey\" authentication"); |
| 419 | goto out; |
| 420 | } |
| 421 | |
| 422 | /* Connect to ssh-agent and try each identity in turn. */ |
| 423 | agent = libssh2_agent_init(s->session); |
| 424 | if (!agent) { |
| 425 | ret = -EINVAL; |
| 426 | session_error_report(s, "failed to initialize ssh-agent support"); |
| 427 | goto out; |
| 428 | } |
| 429 | if (libssh2_agent_connect(agent)) { |
| 430 | ret = -ECONNREFUSED; |
| 431 | session_error_report(s, "failed to connect to ssh-agent"); |
| 432 | goto out; |
| 433 | } |
| 434 | if (libssh2_agent_list_identities(agent)) { |
| 435 | ret = -EINVAL; |
| 436 | session_error_report(s, "failed requesting identities from ssh-agent"); |
| 437 | goto out; |
| 438 | } |
| 439 | |
| 440 | for(;;) { |
| 441 | r = libssh2_agent_get_identity(agent, &identity, prev_identity); |
| 442 | if (r == 1) { /* end of list */ |
| 443 | break; |
| 444 | } |
| 445 | if (r < 0) { |
| 446 | ret = -EINVAL; |
| 447 | session_error_report(s, "failed to obtain identity from ssh-agent"); |
| 448 | goto out; |
| 449 | } |
| 450 | r = libssh2_agent_userauth(agent, user, identity); |
| 451 | if (r == 0) { |
| 452 | /* Authenticated! */ |
| 453 | ret = 0; |
| 454 | goto out; |
| 455 | } |
| 456 | /* Failed to authenticate with this identity, try the next one. */ |
| 457 | prev_identity = identity; |
| 458 | } |
| 459 | |
| 460 | ret = -EPERM; |
| 461 | error_report("failed to authenticate using publickey authentication " |
| 462 | "and the identities held by your ssh-agent"); |
| 463 | |
| 464 | out: |
| 465 | if (agent != NULL) { |
| 466 | /* Note: libssh2 implementation implicitly calls |
| 467 | * libssh2_agent_disconnect if necessary. |
| 468 | */ |
| 469 | libssh2_agent_free(agent); |
| 470 | } |
| 471 | |
| 472 | return ret; |
| 473 | } |
| 474 | |
| 475 | static int connect_to_ssh(BDRVSSHState *s, QDict *options, |
| 476 | int ssh_flags, int creat_mode) |
| 477 | { |
| 478 | int r, ret; |
| 479 | Error *err = NULL; |
| 480 | const char *host, *user, *path, *host_key_check; |
| 481 | int port; |
| 482 | char *hostport = NULL; |
| 483 | |
| 484 | host = qdict_get_str(options, "host"); |
| 485 | |
| 486 | if (qdict_haskey(options, "port")) { |
| 487 | port = qdict_get_int(options, "port"); |
| 488 | } else { |
| 489 | port = 22; |
| 490 | } |
| 491 | |
| 492 | path = qdict_get_str(options, "path"); |
| 493 | |
| 494 | if (qdict_haskey(options, "user")) { |
| 495 | user = qdict_get_str(options, "user"); |
| 496 | } else { |
| 497 | user = g_get_user_name(); |
| 498 | if (!user) { |
| 499 | ret = -errno; |
| 500 | goto err; |
| 501 | } |
| 502 | } |
| 503 | |
| 504 | if (qdict_haskey(options, "host_key_check")) { |
| 505 | host_key_check = qdict_get_str(options, "host_key_check"); |
| 506 | } else { |
| 507 | host_key_check = "yes"; |
| 508 | } |
| 509 | |
| 510 | /* Open the socket and connect. */ |
| 511 | hostport = g_strdup_printf("%s:%d", host, port); |
| 512 | s->sock = inet_connect(hostport, &err); |
| 513 | if (err != NULL) { |
| 514 | ret = -errno; |
| 515 | qerror_report_err(err); |
| 516 | error_free(err); |
| 517 | goto err; |
| 518 | } |
| 519 | |
| 520 | /* Create SSH session. */ |
| 521 | s->session = libssh2_session_init(); |
| 522 | if (!s->session) { |
| 523 | ret = -EINVAL; |
| 524 | session_error_report(s, "failed to initialize libssh2 session"); |
| 525 | goto err; |
| 526 | } |
| 527 | |
| 528 | #if TRACE_LIBSSH2 != 0 |
| 529 | libssh2_trace(s->session, TRACE_LIBSSH2); |
| 530 | #endif |
| 531 | |
| 532 | r = libssh2_session_handshake(s->session, s->sock); |
| 533 | if (r != 0) { |
| 534 | ret = -EINVAL; |
| 535 | session_error_report(s, "failed to establish SSH session"); |
| 536 | goto err; |
| 537 | } |
| 538 | |
| 539 | /* Check the remote host's key against known_hosts. */ |
| 540 | ret = check_host_key(s, host, port, host_key_check); |
| 541 | if (ret < 0) { |
| 542 | goto err; |
| 543 | } |
| 544 | |
| 545 | /* Authenticate. */ |
| 546 | ret = authenticate(s, user); |
| 547 | if (ret < 0) { |
| 548 | goto err; |
| 549 | } |
| 550 | |
| 551 | /* Start SFTP. */ |
| 552 | s->sftp = libssh2_sftp_init(s->session); |
| 553 | if (!s->sftp) { |
| 554 | session_error_report(s, "failed to initialize sftp handle"); |
| 555 | ret = -EINVAL; |
| 556 | goto err; |
| 557 | } |
| 558 | |
| 559 | /* Open the remote file. */ |
| 560 | DPRINTF("opening file %s flags=0x%x creat_mode=0%o", |
| 561 | path, ssh_flags, creat_mode); |
| 562 | s->sftp_handle = libssh2_sftp_open(s->sftp, path, ssh_flags, creat_mode); |
| 563 | if (!s->sftp_handle) { |
| 564 | session_error_report(s, "failed to open remote file '%s'", path); |
| 565 | ret = -EINVAL; |
| 566 | goto err; |
| 567 | } |
| 568 | |
| 569 | r = libssh2_sftp_fstat(s->sftp_handle, &s->attrs); |
| 570 | if (r < 0) { |
| 571 | sftp_error_report(s, "failed to read file attributes"); |
| 572 | return -EINVAL; |
| 573 | } |
| 574 | |
| 575 | /* Delete the options we've used; any not deleted will cause the |
| 576 | * block layer to give an error about unused options. |
| 577 | */ |
| 578 | qdict_del(options, "host"); |
| 579 | qdict_del(options, "port"); |
| 580 | qdict_del(options, "user"); |
| 581 | qdict_del(options, "path"); |
| 582 | qdict_del(options, "host_key_check"); |
| 583 | |
| 584 | g_free(hostport); |
| 585 | return 0; |
| 586 | |
| 587 | err: |
| 588 | if (s->sftp_handle) { |
| 589 | libssh2_sftp_close(s->sftp_handle); |
| 590 | } |
| 591 | s->sftp_handle = NULL; |
| 592 | if (s->sftp) { |
| 593 | libssh2_sftp_shutdown(s->sftp); |
| 594 | } |
| 595 | s->sftp = NULL; |
| 596 | if (s->session) { |
| 597 | libssh2_session_disconnect(s->session, |
| 598 | "from qemu ssh client: " |
| 599 | "error opening connection"); |
| 600 | libssh2_session_free(s->session); |
| 601 | } |
| 602 | s->session = NULL; |
| 603 | g_free(hostport); |
| 604 | |
| 605 | return ret; |
| 606 | } |
| 607 | |
| 608 | static int ssh_file_open(BlockDriverState *bs, const char *filename, |
| 609 | QDict *options, int bdrv_flags) |
| 610 | { |
| 611 | BDRVSSHState *s = bs->opaque; |
| 612 | int ret; |
| 613 | int ssh_flags; |
| 614 | |
| 615 | ssh_state_init(s); |
| 616 | |
| 617 | ssh_flags = LIBSSH2_FXF_READ; |
| 618 | if (bdrv_flags & BDRV_O_RDWR) { |
| 619 | ssh_flags |= LIBSSH2_FXF_WRITE; |
| 620 | } |
| 621 | |
| 622 | /* Start up SSH. */ |
| 623 | ret = connect_to_ssh(s, options, ssh_flags, 0); |
| 624 | if (ret < 0) { |
| 625 | goto err; |
| 626 | } |
| 627 | |
| 628 | /* Go non-blocking. */ |
| 629 | libssh2_session_set_blocking(s->session, 0); |
| 630 | |
| 631 | return 0; |
| 632 | |
| 633 | err: |
| 634 | if (s->sock >= 0) { |
| 635 | close(s->sock); |
| 636 | } |
| 637 | s->sock = -1; |
| 638 | |
| 639 | return ret; |
| 640 | } |
| 641 | |
| 642 | static QEMUOptionParameter ssh_create_options[] = { |
| 643 | { |
| 644 | .name = BLOCK_OPT_SIZE, |
| 645 | .type = OPT_SIZE, |
| 646 | .help = "Virtual disk size" |
| 647 | }, |
| 648 | { NULL } |
| 649 | }; |
| 650 | |
| 651 | static int ssh_create(const char *filename, QEMUOptionParameter *options) |
| 652 | { |
| 653 | int r, ret; |
| 654 | Error *local_err = NULL; |
| 655 | int64_t total_size = 0; |
| 656 | QDict *uri_options = NULL; |
| 657 | BDRVSSHState s; |
| 658 | ssize_t r2; |
| 659 | char c[1] = { '\0' }; |
| 660 | |
| 661 | ssh_state_init(&s); |
| 662 | |
| 663 | /* Get desired file size. */ |
| 664 | while (options && options->name) { |
| 665 | if (!strcmp(options->name, BLOCK_OPT_SIZE)) { |
| 666 | total_size = options->value.n; |
| 667 | } |
| 668 | options++; |
| 669 | } |
| 670 | DPRINTF("total_size=%" PRIi64, total_size); |
| 671 | |
| 672 | uri_options = qdict_new(); |
| 673 | r = parse_uri(filename, uri_options, &local_err); |
| 674 | if (r < 0) { |
| 675 | qerror_report_err(local_err); |
| 676 | error_free(local_err); |
| 677 | ret = r; |
| 678 | goto out; |
| 679 | } |
| 680 | |
| 681 | r = connect_to_ssh(&s, uri_options, |
| 682 | LIBSSH2_FXF_READ|LIBSSH2_FXF_WRITE| |
| 683 | LIBSSH2_FXF_CREAT|LIBSSH2_FXF_TRUNC, 0644); |
| 684 | if (r < 0) { |
| 685 | ret = r; |
| 686 | goto out; |
| 687 | } |
| 688 | |
| 689 | if (total_size > 0) { |
| 690 | libssh2_sftp_seek64(s.sftp_handle, total_size-1); |
| 691 | r2 = libssh2_sftp_write(s.sftp_handle, c, 1); |
| 692 | if (r2 < 0) { |
| 693 | sftp_error_report(&s, "truncate failed"); |
| 694 | ret = -EINVAL; |
| 695 | goto out; |
| 696 | } |
| 697 | s.attrs.filesize = total_size; |
| 698 | } |
| 699 | |
| 700 | ret = 0; |
| 701 | |
| 702 | out: |
| 703 | ssh_state_free(&s); |
| 704 | if (uri_options != NULL) { |
| 705 | QDECREF(uri_options); |
| 706 | } |
| 707 | return ret; |
| 708 | } |
| 709 | |
| 710 | static void ssh_close(BlockDriverState *bs) |
| 711 | { |
| 712 | BDRVSSHState *s = bs->opaque; |
| 713 | |
| 714 | ssh_state_free(s); |
| 715 | } |
| 716 | |
| 717 | static void restart_coroutine(void *opaque) |
| 718 | { |
| 719 | Coroutine *co = opaque; |
| 720 | |
| 721 | DPRINTF("co=%p", co); |
| 722 | |
| 723 | qemu_coroutine_enter(co, NULL); |
| 724 | } |
| 725 | |
| 726 | /* Always true because when we have called set_fd_handler there is |
| 727 | * always a request being processed. |
| 728 | */ |
| 729 | static int return_true(void *opaque) |
| 730 | { |
| 731 | return 1; |
| 732 | } |
| 733 | |
| 734 | static coroutine_fn void set_fd_handler(BDRVSSHState *s) |
| 735 | { |
| 736 | int r; |
| 737 | IOHandler *rd_handler = NULL, *wr_handler = NULL; |
| 738 | Coroutine *co = qemu_coroutine_self(); |
| 739 | |
| 740 | r = libssh2_session_block_directions(s->session); |
| 741 | |
| 742 | if (r & LIBSSH2_SESSION_BLOCK_INBOUND) { |
| 743 | rd_handler = restart_coroutine; |
| 744 | } |
| 745 | if (r & LIBSSH2_SESSION_BLOCK_OUTBOUND) { |
| 746 | wr_handler = restart_coroutine; |
| 747 | } |
| 748 | |
| 749 | DPRINTF("s->sock=%d rd_handler=%p wr_handler=%p", s->sock, |
| 750 | rd_handler, wr_handler); |
| 751 | |
| 752 | qemu_aio_set_fd_handler(s->sock, rd_handler, wr_handler, return_true, co); |
| 753 | } |
| 754 | |
| 755 | static coroutine_fn void clear_fd_handler(BDRVSSHState *s) |
| 756 | { |
| 757 | DPRINTF("s->sock=%d", s->sock); |
| 758 | qemu_aio_set_fd_handler(s->sock, NULL, NULL, NULL, NULL); |
| 759 | } |
| 760 | |
| 761 | /* A non-blocking call returned EAGAIN, so yield, ensuring the |
| 762 | * handlers are set up so that we'll be rescheduled when there is an |
| 763 | * interesting event on the socket. |
| 764 | */ |
| 765 | static coroutine_fn void co_yield(BDRVSSHState *s) |
| 766 | { |
| 767 | set_fd_handler(s); |
| 768 | qemu_coroutine_yield(); |
| 769 | clear_fd_handler(s); |
| 770 | } |
| 771 | |
| 772 | /* SFTP has a function `libssh2_sftp_seek64' which seeks to a position |
| 773 | * in the remote file. Notice that it just updates a field in the |
| 774 | * sftp_handle structure, so there is no network traffic and it cannot |
| 775 | * fail. |
| 776 | * |
| 777 | * However, `libssh2_sftp_seek64' does have a catastrophic effect on |
| 778 | * performance since it causes the handle to throw away all in-flight |
| 779 | * reads and buffered readahead data. Therefore this function tries |
| 780 | * to be intelligent about when to call the underlying libssh2 function. |
| 781 | */ |
| 782 | #define SSH_SEEK_WRITE 0 |
| 783 | #define SSH_SEEK_READ 1 |
| 784 | #define SSH_SEEK_FORCE 2 |
| 785 | |
| 786 | static void ssh_seek(BDRVSSHState *s, int64_t offset, int flags) |
| 787 | { |
| 788 | bool op_read = (flags & SSH_SEEK_READ) != 0; |
| 789 | bool force = (flags & SSH_SEEK_FORCE) != 0; |
| 790 | |
| 791 | if (force || op_read != s->offset_op_read || offset != s->offset) { |
| 792 | DPRINTF("seeking to offset=%" PRIi64, offset); |
| 793 | libssh2_sftp_seek64(s->sftp_handle, offset); |
| 794 | s->offset = offset; |
| 795 | s->offset_op_read = op_read; |
| 796 | } |
| 797 | } |
| 798 | |
| 799 | static coroutine_fn int ssh_read(BDRVSSHState *s, |
| 800 | int64_t offset, size_t size, |
| 801 | QEMUIOVector *qiov) |
| 802 | { |
| 803 | ssize_t r; |
| 804 | size_t got; |
| 805 | char *buf, *end_of_vec; |
| 806 | struct iovec *i; |
| 807 | |
| 808 | DPRINTF("offset=%" PRIi64 " size=%zu", offset, size); |
| 809 | |
| 810 | ssh_seek(s, offset, SSH_SEEK_READ); |
| 811 | |
| 812 | /* This keeps track of the current iovec element ('i'), where we |
| 813 | * will write to next ('buf'), and the end of the current iovec |
| 814 | * ('end_of_vec'). |
| 815 | */ |
| 816 | i = &qiov->iov[0]; |
| 817 | buf = i->iov_base; |
| 818 | end_of_vec = i->iov_base + i->iov_len; |
| 819 | |
| 820 | /* libssh2 has a hard-coded limit of 2000 bytes per request, |
| 821 | * although it will also do readahead behind our backs. Therefore |
| 822 | * we may have to do repeated reads here until we have read 'size' |
| 823 | * bytes. |
| 824 | */ |
| 825 | for (got = 0; got < size; ) { |
| 826 | again: |
| 827 | DPRINTF("sftp_read buf=%p size=%zu", buf, end_of_vec - buf); |
| 828 | r = libssh2_sftp_read(s->sftp_handle, buf, end_of_vec - buf); |
| 829 | DPRINTF("sftp_read returned %zd", r); |
| 830 | |
| 831 | if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) { |
| 832 | co_yield(s); |
| 833 | goto again; |
| 834 | } |
| 835 | if (r < 0) { |
| 836 | sftp_error_report(s, "read failed"); |
| 837 | s->offset = -1; |
| 838 | return -EIO; |
| 839 | } |
| 840 | if (r == 0) { |
| 841 | /* EOF: Short read so pad the buffer with zeroes and return it. */ |
| 842 | qemu_iovec_memset(qiov, got, 0, size - got); |
| 843 | return 0; |
| 844 | } |
| 845 | |
| 846 | got += r; |
| 847 | buf += r; |
| 848 | s->offset += r; |
| 849 | if (buf >= end_of_vec && got < size) { |
| 850 | i++; |
| 851 | buf = i->iov_base; |
| 852 | end_of_vec = i->iov_base + i->iov_len; |
| 853 | } |
| 854 | } |
| 855 | |
| 856 | return 0; |
| 857 | } |
| 858 | |
| 859 | static coroutine_fn int ssh_co_readv(BlockDriverState *bs, |
| 860 | int64_t sector_num, |
| 861 | int nb_sectors, QEMUIOVector *qiov) |
| 862 | { |
| 863 | BDRVSSHState *s = bs->opaque; |
| 864 | int ret; |
| 865 | |
| 866 | qemu_co_mutex_lock(&s->lock); |
| 867 | ret = ssh_read(s, sector_num * BDRV_SECTOR_SIZE, |
| 868 | nb_sectors * BDRV_SECTOR_SIZE, qiov); |
| 869 | qemu_co_mutex_unlock(&s->lock); |
| 870 | |
| 871 | return ret; |
| 872 | } |
| 873 | |
| 874 | static int ssh_write(BDRVSSHState *s, |
| 875 | int64_t offset, size_t size, |
| 876 | QEMUIOVector *qiov) |
| 877 | { |
| 878 | ssize_t r; |
| 879 | size_t written; |
| 880 | char *buf, *end_of_vec; |
| 881 | struct iovec *i; |
| 882 | |
| 883 | DPRINTF("offset=%" PRIi64 " size=%zu", offset, size); |
| 884 | |
| 885 | ssh_seek(s, offset, SSH_SEEK_WRITE); |
| 886 | |
| 887 | /* This keeps track of the current iovec element ('i'), where we |
| 888 | * will read from next ('buf'), and the end of the current iovec |
| 889 | * ('end_of_vec'). |
| 890 | */ |
| 891 | i = &qiov->iov[0]; |
| 892 | buf = i->iov_base; |
| 893 | end_of_vec = i->iov_base + i->iov_len; |
| 894 | |
| 895 | for (written = 0; written < size; ) { |
| 896 | again: |
| 897 | DPRINTF("sftp_write buf=%p size=%zu", buf, end_of_vec - buf); |
| 898 | r = libssh2_sftp_write(s->sftp_handle, buf, end_of_vec - buf); |
| 899 | DPRINTF("sftp_write returned %zd", r); |
| 900 | |
| 901 | if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) { |
| 902 | co_yield(s); |
| 903 | goto again; |
| 904 | } |
| 905 | if (r < 0) { |
| 906 | sftp_error_report(s, "write failed"); |
| 907 | s->offset = -1; |
| 908 | return -EIO; |
| 909 | } |
| 910 | /* The libssh2 API is very unclear about this. A comment in |
| 911 | * the code says "nothing was acked, and no EAGAIN was |
| 912 | * received!" which apparently means that no data got sent |
| 913 | * out, and the underlying channel didn't return any EAGAIN |
| 914 | * indication. I think this is a bug in either libssh2 or |
| 915 | * OpenSSH (server-side). In any case, forcing a seek (to |
| 916 | * discard libssh2 internal buffers), and then trying again |
| 917 | * works for me. |
| 918 | */ |
| 919 | if (r == 0) { |
| 920 | ssh_seek(s, offset + written, SSH_SEEK_WRITE|SSH_SEEK_FORCE); |
| 921 | co_yield(s); |
| 922 | goto again; |
| 923 | } |
| 924 | |
| 925 | written += r; |
| 926 | buf += r; |
| 927 | s->offset += r; |
| 928 | if (buf >= end_of_vec && written < size) { |
| 929 | i++; |
| 930 | buf = i->iov_base; |
| 931 | end_of_vec = i->iov_base + i->iov_len; |
| 932 | } |
| 933 | |
| 934 | if (offset + written > s->attrs.filesize) |
| 935 | s->attrs.filesize = offset + written; |
| 936 | } |
| 937 | |
| 938 | return 0; |
| 939 | } |
| 940 | |
| 941 | static coroutine_fn int ssh_co_writev(BlockDriverState *bs, |
| 942 | int64_t sector_num, |
| 943 | int nb_sectors, QEMUIOVector *qiov) |
| 944 | { |
| 945 | BDRVSSHState *s = bs->opaque; |
| 946 | int ret; |
| 947 | |
| 948 | qemu_co_mutex_lock(&s->lock); |
| 949 | ret = ssh_write(s, sector_num * BDRV_SECTOR_SIZE, |
| 950 | nb_sectors * BDRV_SECTOR_SIZE, qiov); |
| 951 | qemu_co_mutex_unlock(&s->lock); |
| 952 | |
| 953 | return ret; |
| 954 | } |
| 955 | |
| 956 | static int64_t ssh_getlength(BlockDriverState *bs) |
| 957 | { |
| 958 | BDRVSSHState *s = bs->opaque; |
| 959 | int64_t length; |
| 960 | |
| 961 | /* Note we cannot make a libssh2 call here. */ |
| 962 | length = (int64_t) s->attrs.filesize; |
| 963 | DPRINTF("length=%" PRIi64, length); |
| 964 | |
| 965 | return length; |
| 966 | } |
| 967 | |
| 968 | static BlockDriver bdrv_ssh = { |
| 969 | .format_name = "ssh", |
| 970 | .protocol_name = "ssh", |
| 971 | .instance_size = sizeof(BDRVSSHState), |
| 972 | .bdrv_parse_filename = ssh_parse_filename, |
| 973 | .bdrv_file_open = ssh_file_open, |
| 974 | .bdrv_create = ssh_create, |
| 975 | .bdrv_close = ssh_close, |
| 976 | .bdrv_co_readv = ssh_co_readv, |
| 977 | .bdrv_co_writev = ssh_co_writev, |
| 978 | .bdrv_getlength = ssh_getlength, |
| 979 | .create_options = ssh_create_options, |
| 980 | }; |
| 981 | |
| 982 | static void bdrv_ssh_init(void) |
| 983 | { |
| 984 | int r; |
| 985 | |
| 986 | r = libssh2_init(0); |
| 987 | if (r != 0) { |
| 988 | fprintf(stderr, "libssh2 initialization failed, %d\n", r); |
| 989 | exit(EXIT_FAILURE); |
| 990 | } |
| 991 | |
| 992 | bdrv_register(&bdrv_ssh); |
| 993 | } |
| 994 | |
| 995 | block_init(bdrv_ssh_init); |