tcg: add CONFIG_TCG guards in headers
[qemu/ar7.git] / block / ssh.c
blob52964416da23646b019639c4a2ffa66f9524c7f6
1 /*
2 * Secure Shell (ssh) backend for QEMU.
4 * Copyright (C) 2013 Red Hat Inc., Richard W.M. Jones <rjones@redhat.com>
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:
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
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.
25 #include "qemu/osdep.h"
27 #include <libssh2.h>
28 #include <libssh2_sftp.h>
30 #include "block/block_int.h"
31 #include "qapi/error.h"
32 #include "qemu/error-report.h"
33 #include "qemu/cutils.h"
34 #include "qemu/sockets.h"
35 #include "qemu/uri.h"
36 #include "qapi-visit.h"
37 #include "qapi/qmp/qstring.h"
38 #include "qapi/qobject-input-visitor.h"
39 #include "qapi/qobject-output-visitor.h"
41 /* DEBUG_SSH=1 enables the DPRINTF (debugging printf) statements in
42 * this block driver code.
44 * TRACE_LIBSSH2=<bitmask> enables tracing in libssh2 itself. Note
45 * that this requires that libssh2 was specially compiled with the
46 * `./configure --enable-debug' option, so most likely you will have
47 * to compile it yourself. The meaning of <bitmask> is described
48 * here: http://www.libssh2.org/libssh2_trace.html
50 #define DEBUG_SSH 0
51 #define TRACE_LIBSSH2 0 /* or try: LIBSSH2_TRACE_SFTP */
53 #define DPRINTF(fmt, ...) \
54 do { \
55 if (DEBUG_SSH) { \
56 fprintf(stderr, "ssh: %-15s " fmt "\n", \
57 __func__, ##__VA_ARGS__); \
58 } \
59 } while (0)
61 typedef struct BDRVSSHState {
62 /* Coroutine. */
63 CoMutex lock;
65 /* SSH connection. */
66 int sock; /* socket */
67 LIBSSH2_SESSION *session; /* ssh session */
68 LIBSSH2_SFTP *sftp; /* sftp session */
69 LIBSSH2_SFTP_HANDLE *sftp_handle; /* sftp remote file handle */
71 /* See ssh_seek() function below. */
72 int64_t offset;
73 bool offset_op_read;
75 /* File attributes at open. We try to keep the .filesize field
76 * updated if it changes (eg by writing at the end of the file).
78 LIBSSH2_SFTP_ATTRIBUTES attrs;
80 InetSocketAddress *inet;
82 /* Used to warn if 'flush' is not supported. */
83 bool unsafe_flush_warning;
84 } BDRVSSHState;
86 static void ssh_state_init(BDRVSSHState *s)
88 memset(s, 0, sizeof *s);
89 s->sock = -1;
90 s->offset = -1;
91 qemu_co_mutex_init(&s->lock);
94 static void ssh_state_free(BDRVSSHState *s)
96 if (s->sftp_handle) {
97 libssh2_sftp_close(s->sftp_handle);
99 if (s->sftp) {
100 libssh2_sftp_shutdown(s->sftp);
102 if (s->session) {
103 libssh2_session_disconnect(s->session,
104 "from qemu ssh client: "
105 "user closed the connection");
106 libssh2_session_free(s->session);
108 if (s->sock >= 0) {
109 close(s->sock);
113 static void GCC_FMT_ATTR(3, 4)
114 session_error_setg(Error **errp, BDRVSSHState *s, const char *fs, ...)
116 va_list args;
117 char *msg;
119 va_start(args, fs);
120 msg = g_strdup_vprintf(fs, args);
121 va_end(args);
123 if (s->session) {
124 char *ssh_err;
125 int ssh_err_code;
127 /* This is not an errno. See <libssh2.h>. */
128 ssh_err_code = libssh2_session_last_error(s->session,
129 &ssh_err, NULL, 0);
130 error_setg(errp, "%s: %s (libssh2 error code: %d)",
131 msg, ssh_err, ssh_err_code);
132 } else {
133 error_setg(errp, "%s", msg);
135 g_free(msg);
138 static void GCC_FMT_ATTR(3, 4)
139 sftp_error_setg(Error **errp, BDRVSSHState *s, const char *fs, ...)
141 va_list args;
142 char *msg;
144 va_start(args, fs);
145 msg = g_strdup_vprintf(fs, args);
146 va_end(args);
148 if (s->sftp) {
149 char *ssh_err;
150 int ssh_err_code;
151 unsigned long sftp_err_code;
153 /* This is not an errno. See <libssh2.h>. */
154 ssh_err_code = libssh2_session_last_error(s->session,
155 &ssh_err, NULL, 0);
156 /* See <libssh2_sftp.h>. */
157 sftp_err_code = libssh2_sftp_last_error((s)->sftp);
159 error_setg(errp,
160 "%s: %s (libssh2 error code: %d, sftp error code: %lu)",
161 msg, ssh_err, ssh_err_code, sftp_err_code);
162 } else {
163 error_setg(errp, "%s", msg);
165 g_free(msg);
168 static void GCC_FMT_ATTR(2, 3)
169 sftp_error_report(BDRVSSHState *s, const char *fs, ...)
171 va_list args;
173 va_start(args, fs);
174 error_vprintf(fs, args);
176 if ((s)->sftp) {
177 char *ssh_err;
178 int ssh_err_code;
179 unsigned long sftp_err_code;
181 /* This is not an errno. See <libssh2.h>. */
182 ssh_err_code = libssh2_session_last_error(s->session,
183 &ssh_err, NULL, 0);
184 /* See <libssh2_sftp.h>. */
185 sftp_err_code = libssh2_sftp_last_error((s)->sftp);
187 error_printf(": %s (libssh2 error code: %d, sftp error code: %lu)",
188 ssh_err, ssh_err_code, sftp_err_code);
191 va_end(args);
192 error_printf("\n");
195 static int parse_uri(const char *filename, QDict *options, Error **errp)
197 URI *uri = NULL;
198 QueryParams *qp;
199 char *port_str;
200 int i;
202 uri = uri_parse(filename);
203 if (!uri) {
204 return -EINVAL;
207 if (g_strcmp0(uri->scheme, "ssh") != 0) {
208 error_setg(errp, "URI scheme must be 'ssh'");
209 goto err;
212 if (!uri->server || strcmp(uri->server, "") == 0) {
213 error_setg(errp, "missing hostname in URI");
214 goto err;
217 if (!uri->path || strcmp(uri->path, "") == 0) {
218 error_setg(errp, "missing remote path in URI");
219 goto err;
222 qp = query_params_parse(uri->query);
223 if (!qp) {
224 error_setg(errp, "could not parse query parameters");
225 goto err;
228 if(uri->user && strcmp(uri->user, "") != 0) {
229 qdict_put_str(options, "user", uri->user);
232 qdict_put_str(options, "server.host", uri->server);
234 port_str = g_strdup_printf("%d", uri->port ?: 22);
235 qdict_put_str(options, "server.port", port_str);
236 g_free(port_str);
238 qdict_put_str(options, "path", uri->path);
240 /* Pick out any query parameters that we understand, and ignore
241 * the rest.
243 for (i = 0; i < qp->n; ++i) {
244 if (strcmp(qp->p[i].name, "host_key_check") == 0) {
245 qdict_put_str(options, "host_key_check", qp->p[i].value);
249 query_params_free(qp);
250 uri_free(uri);
251 return 0;
253 err:
254 if (uri) {
255 uri_free(uri);
257 return -EINVAL;
260 static bool ssh_has_filename_options_conflict(QDict *options, Error **errp)
262 const QDictEntry *qe;
264 for (qe = qdict_first(options); qe; qe = qdict_next(options, qe)) {
265 if (!strcmp(qe->key, "host") ||
266 !strcmp(qe->key, "port") ||
267 !strcmp(qe->key, "path") ||
268 !strcmp(qe->key, "user") ||
269 !strcmp(qe->key, "host_key_check") ||
270 strstart(qe->key, "server.", NULL))
272 error_setg(errp, "Option '%s' cannot be used with a file name",
273 qe->key);
274 return true;
278 return false;
281 static void ssh_parse_filename(const char *filename, QDict *options,
282 Error **errp)
284 if (ssh_has_filename_options_conflict(options, errp)) {
285 return;
288 parse_uri(filename, options, errp);
291 static int check_host_key_knownhosts(BDRVSSHState *s,
292 const char *host, int port, Error **errp)
294 const char *home;
295 char *knh_file = NULL;
296 LIBSSH2_KNOWNHOSTS *knh = NULL;
297 struct libssh2_knownhost *found;
298 int ret, r;
299 const char *hostkey;
300 size_t len;
301 int type;
303 hostkey = libssh2_session_hostkey(s->session, &len, &type);
304 if (!hostkey) {
305 ret = -EINVAL;
306 session_error_setg(errp, s, "failed to read remote host key");
307 goto out;
310 knh = libssh2_knownhost_init(s->session);
311 if (!knh) {
312 ret = -EINVAL;
313 session_error_setg(errp, s,
314 "failed to initialize known hosts support");
315 goto out;
318 home = getenv("HOME");
319 if (home) {
320 knh_file = g_strdup_printf("%s/.ssh/known_hosts", home);
321 } else {
322 knh_file = g_strdup_printf("/root/.ssh/known_hosts");
325 /* Read all known hosts from OpenSSH-style known_hosts file. */
326 libssh2_knownhost_readfile(knh, knh_file, LIBSSH2_KNOWNHOST_FILE_OPENSSH);
328 r = libssh2_knownhost_checkp(knh, host, port, hostkey, len,
329 LIBSSH2_KNOWNHOST_TYPE_PLAIN|
330 LIBSSH2_KNOWNHOST_KEYENC_RAW,
331 &found);
332 switch (r) {
333 case LIBSSH2_KNOWNHOST_CHECK_MATCH:
334 /* OK */
335 DPRINTF("host key OK: %s", found->key);
336 break;
337 case LIBSSH2_KNOWNHOST_CHECK_MISMATCH:
338 ret = -EINVAL;
339 session_error_setg(errp, s,
340 "host key does not match the one in known_hosts"
341 " (found key %s)", found->key);
342 goto out;
343 case LIBSSH2_KNOWNHOST_CHECK_NOTFOUND:
344 ret = -EINVAL;
345 session_error_setg(errp, s, "no host key was found in known_hosts");
346 goto out;
347 case LIBSSH2_KNOWNHOST_CHECK_FAILURE:
348 ret = -EINVAL;
349 session_error_setg(errp, s,
350 "failure matching the host key with known_hosts");
351 goto out;
352 default:
353 ret = -EINVAL;
354 session_error_setg(errp, s, "unknown error matching the host key"
355 " with known_hosts (%d)", r);
356 goto out;
359 /* known_hosts checking successful. */
360 ret = 0;
362 out:
363 if (knh != NULL) {
364 libssh2_knownhost_free(knh);
366 g_free(knh_file);
367 return ret;
370 static unsigned hex2decimal(char ch)
372 if (ch >= '0' && ch <= '9') {
373 return (ch - '0');
374 } else if (ch >= 'a' && ch <= 'f') {
375 return 10 + (ch - 'a');
376 } else if (ch >= 'A' && ch <= 'F') {
377 return 10 + (ch - 'A');
380 return -1;
383 /* Compare the binary fingerprint (hash of host key) with the
384 * host_key_check parameter.
386 static int compare_fingerprint(const unsigned char *fingerprint, size_t len,
387 const char *host_key_check)
389 unsigned c;
391 while (len > 0) {
392 while (*host_key_check == ':')
393 host_key_check++;
394 if (!qemu_isxdigit(host_key_check[0]) ||
395 !qemu_isxdigit(host_key_check[1]))
396 return 1;
397 c = hex2decimal(host_key_check[0]) * 16 +
398 hex2decimal(host_key_check[1]);
399 if (c - *fingerprint != 0)
400 return c - *fingerprint;
401 fingerprint++;
402 len--;
403 host_key_check += 2;
405 return *host_key_check - '\0';
408 static int
409 check_host_key_hash(BDRVSSHState *s, const char *hash,
410 int hash_type, size_t fingerprint_len, Error **errp)
412 const char *fingerprint;
414 fingerprint = libssh2_hostkey_hash(s->session, hash_type);
415 if (!fingerprint) {
416 session_error_setg(errp, s, "failed to read remote host key");
417 return -EINVAL;
420 if(compare_fingerprint((unsigned char *) fingerprint, fingerprint_len,
421 hash) != 0) {
422 error_setg(errp, "remote host key does not match host_key_check '%s'",
423 hash);
424 return -EPERM;
427 return 0;
430 static int check_host_key(BDRVSSHState *s, const char *host, int port,
431 const char *host_key_check, Error **errp)
433 /* host_key_check=no */
434 if (strcmp(host_key_check, "no") == 0) {
435 return 0;
438 /* host_key_check=md5:xx:yy:zz:... */
439 if (strncmp(host_key_check, "md5:", 4) == 0) {
440 return check_host_key_hash(s, &host_key_check[4],
441 LIBSSH2_HOSTKEY_HASH_MD5, 16, errp);
444 /* host_key_check=sha1:xx:yy:zz:... */
445 if (strncmp(host_key_check, "sha1:", 5) == 0) {
446 return check_host_key_hash(s, &host_key_check[5],
447 LIBSSH2_HOSTKEY_HASH_SHA1, 20, errp);
450 /* host_key_check=yes */
451 if (strcmp(host_key_check, "yes") == 0) {
452 return check_host_key_knownhosts(s, host, port, errp);
455 error_setg(errp, "unknown host_key_check setting (%s)", host_key_check);
456 return -EINVAL;
459 static int authenticate(BDRVSSHState *s, const char *user, Error **errp)
461 int r, ret;
462 const char *userauthlist;
463 LIBSSH2_AGENT *agent = NULL;
464 struct libssh2_agent_publickey *identity;
465 struct libssh2_agent_publickey *prev_identity = NULL;
467 userauthlist = libssh2_userauth_list(s->session, user, strlen(user));
468 if (strstr(userauthlist, "publickey") == NULL) {
469 ret = -EPERM;
470 error_setg(errp,
471 "remote server does not support \"publickey\" authentication");
472 goto out;
475 /* Connect to ssh-agent and try each identity in turn. */
476 agent = libssh2_agent_init(s->session);
477 if (!agent) {
478 ret = -EINVAL;
479 session_error_setg(errp, s, "failed to initialize ssh-agent support");
480 goto out;
482 if (libssh2_agent_connect(agent)) {
483 ret = -ECONNREFUSED;
484 session_error_setg(errp, s, "failed to connect to ssh-agent");
485 goto out;
487 if (libssh2_agent_list_identities(agent)) {
488 ret = -EINVAL;
489 session_error_setg(errp, s,
490 "failed requesting identities from ssh-agent");
491 goto out;
494 for(;;) {
495 r = libssh2_agent_get_identity(agent, &identity, prev_identity);
496 if (r == 1) { /* end of list */
497 break;
499 if (r < 0) {
500 ret = -EINVAL;
501 session_error_setg(errp, s,
502 "failed to obtain identity from ssh-agent");
503 goto out;
505 r = libssh2_agent_userauth(agent, user, identity);
506 if (r == 0) {
507 /* Authenticated! */
508 ret = 0;
509 goto out;
511 /* Failed to authenticate with this identity, try the next one. */
512 prev_identity = identity;
515 ret = -EPERM;
516 error_setg(errp, "failed to authenticate using publickey authentication "
517 "and the identities held by your ssh-agent");
519 out:
520 if (agent != NULL) {
521 /* Note: libssh2 implementation implicitly calls
522 * libssh2_agent_disconnect if necessary.
524 libssh2_agent_free(agent);
527 return ret;
530 static QemuOptsList ssh_runtime_opts = {
531 .name = "ssh",
532 .head = QTAILQ_HEAD_INITIALIZER(ssh_runtime_opts.head),
533 .desc = {
535 .name = "host",
536 .type = QEMU_OPT_STRING,
537 .help = "Host to connect to",
540 .name = "port",
541 .type = QEMU_OPT_NUMBER,
542 .help = "Port to connect to",
545 .name = "path",
546 .type = QEMU_OPT_STRING,
547 .help = "Path of the image on the host",
550 .name = "user",
551 .type = QEMU_OPT_STRING,
552 .help = "User as which to connect",
555 .name = "host_key_check",
556 .type = QEMU_OPT_STRING,
557 .help = "Defines how and what to check the host key against",
562 static bool ssh_process_legacy_socket_options(QDict *output_opts,
563 QemuOpts *legacy_opts,
564 Error **errp)
566 const char *host = qemu_opt_get(legacy_opts, "host");
567 const char *port = qemu_opt_get(legacy_opts, "port");
569 if (!host && port) {
570 error_setg(errp, "port may not be used without host");
571 return false;
574 if (host) {
575 qdict_put_str(output_opts, "server.host", host);
576 qdict_put_str(output_opts, "server.port", port ?: stringify(22));
579 return true;
582 static InetSocketAddress *ssh_config(QDict *options, Error **errp)
584 InetSocketAddress *inet = NULL;
585 QDict *addr = NULL;
586 QObject *crumpled_addr = NULL;
587 Visitor *iv = NULL;
588 Error *local_error = NULL;
590 qdict_extract_subqdict(options, &addr, "server.");
591 if (!qdict_size(addr)) {
592 error_setg(errp, "SSH server address missing");
593 goto out;
596 crumpled_addr = qdict_crumple(addr, errp);
597 if (!crumpled_addr) {
598 goto out;
602 * FIXME .numeric, .to, .ipv4 or .ipv6 don't work with -drive.
603 * .to doesn't matter, it's ignored anyway.
604 * That's because when @options come from -blockdev or
605 * blockdev_add, members are typed according to the QAPI schema,
606 * but when they come from -drive, they're all QString. The
607 * visitor expects the former.
609 iv = qobject_input_visitor_new(crumpled_addr);
610 visit_type_InetSocketAddress(iv, NULL, &inet, &local_error);
611 if (local_error) {
612 error_propagate(errp, local_error);
613 goto out;
616 out:
617 QDECREF(addr);
618 qobject_decref(crumpled_addr);
619 visit_free(iv);
620 return inet;
623 static int connect_to_ssh(BDRVSSHState *s, QDict *options,
624 int ssh_flags, int creat_mode, Error **errp)
626 int r, ret;
627 QemuOpts *opts = NULL;
628 Error *local_err = NULL;
629 const char *user, *path, *host_key_check;
630 long port = 0;
632 opts = qemu_opts_create(&ssh_runtime_opts, NULL, 0, &error_abort);
633 qemu_opts_absorb_qdict(opts, options, &local_err);
634 if (local_err) {
635 ret = -EINVAL;
636 error_propagate(errp, local_err);
637 goto err;
640 if (!ssh_process_legacy_socket_options(options, opts, errp)) {
641 ret = -EINVAL;
642 goto err;
645 path = qemu_opt_get(opts, "path");
646 if (!path) {
647 ret = -EINVAL;
648 error_setg(errp, "No path was specified");
649 goto err;
652 user = qemu_opt_get(opts, "user");
653 if (!user) {
654 user = g_get_user_name();
655 if (!user) {
656 error_setg_errno(errp, errno, "Can't get user name");
657 ret = -errno;
658 goto err;
662 host_key_check = qemu_opt_get(opts, "host_key_check");
663 if (!host_key_check) {
664 host_key_check = "yes";
667 /* Pop the config into our state object, Exit if invalid */
668 s->inet = ssh_config(options, errp);
669 if (!s->inet) {
670 ret = -EINVAL;
671 goto err;
674 if (qemu_strtol(s->inet->port, NULL, 10, &port) < 0) {
675 error_setg(errp, "Use only numeric port value");
676 ret = -EINVAL;
677 goto err;
680 /* Open the socket and connect. */
681 s->sock = inet_connect_saddr(s->inet, NULL, NULL, errp);
682 if (s->sock < 0) {
683 ret = -EIO;
684 goto err;
687 /* Create SSH session. */
688 s->session = libssh2_session_init();
689 if (!s->session) {
690 ret = -EINVAL;
691 session_error_setg(errp, s, "failed to initialize libssh2 session");
692 goto err;
695 #if TRACE_LIBSSH2 != 0
696 libssh2_trace(s->session, TRACE_LIBSSH2);
697 #endif
699 r = libssh2_session_handshake(s->session, s->sock);
700 if (r != 0) {
701 ret = -EINVAL;
702 session_error_setg(errp, s, "failed to establish SSH session");
703 goto err;
706 /* Check the remote host's key against known_hosts. */
707 ret = check_host_key(s, s->inet->host, port, host_key_check,
708 errp);
709 if (ret < 0) {
710 goto err;
713 /* Authenticate. */
714 ret = authenticate(s, user, errp);
715 if (ret < 0) {
716 goto err;
719 /* Start SFTP. */
720 s->sftp = libssh2_sftp_init(s->session);
721 if (!s->sftp) {
722 session_error_setg(errp, s, "failed to initialize sftp handle");
723 ret = -EINVAL;
724 goto err;
727 /* Open the remote file. */
728 DPRINTF("opening file %s flags=0x%x creat_mode=0%o",
729 path, ssh_flags, creat_mode);
730 s->sftp_handle = libssh2_sftp_open(s->sftp, path, ssh_flags, creat_mode);
731 if (!s->sftp_handle) {
732 session_error_setg(errp, s, "failed to open remote file '%s'", path);
733 ret = -EINVAL;
734 goto err;
737 qemu_opts_del(opts);
739 r = libssh2_sftp_fstat(s->sftp_handle, &s->attrs);
740 if (r < 0) {
741 sftp_error_setg(errp, s, "failed to read file attributes");
742 return -EINVAL;
745 return 0;
747 err:
748 if (s->sftp_handle) {
749 libssh2_sftp_close(s->sftp_handle);
751 s->sftp_handle = NULL;
752 if (s->sftp) {
753 libssh2_sftp_shutdown(s->sftp);
755 s->sftp = NULL;
756 if (s->session) {
757 libssh2_session_disconnect(s->session,
758 "from qemu ssh client: "
759 "error opening connection");
760 libssh2_session_free(s->session);
762 s->session = NULL;
764 qemu_opts_del(opts);
766 return ret;
769 static int ssh_file_open(BlockDriverState *bs, QDict *options, int bdrv_flags,
770 Error **errp)
772 BDRVSSHState *s = bs->opaque;
773 int ret;
774 int ssh_flags;
776 ssh_state_init(s);
778 ssh_flags = LIBSSH2_FXF_READ;
779 if (bdrv_flags & BDRV_O_RDWR) {
780 ssh_flags |= LIBSSH2_FXF_WRITE;
783 /* Start up SSH. */
784 ret = connect_to_ssh(s, options, ssh_flags, 0, errp);
785 if (ret < 0) {
786 goto err;
789 /* Go non-blocking. */
790 libssh2_session_set_blocking(s->session, 0);
792 return 0;
794 err:
795 if (s->sock >= 0) {
796 close(s->sock);
798 s->sock = -1;
800 return ret;
803 static QemuOptsList ssh_create_opts = {
804 .name = "ssh-create-opts",
805 .head = QTAILQ_HEAD_INITIALIZER(ssh_create_opts.head),
806 .desc = {
808 .name = BLOCK_OPT_SIZE,
809 .type = QEMU_OPT_SIZE,
810 .help = "Virtual disk size"
812 { /* end of list */ }
816 static int ssh_create(const char *filename, QemuOpts *opts, Error **errp)
818 int r, ret;
819 int64_t total_size = 0;
820 QDict *uri_options = NULL;
821 BDRVSSHState s;
822 ssize_t r2;
823 char c[1] = { '\0' };
825 ssh_state_init(&s);
827 /* Get desired file size. */
828 total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
829 BDRV_SECTOR_SIZE);
830 DPRINTF("total_size=%" PRIi64, total_size);
832 uri_options = qdict_new();
833 r = parse_uri(filename, uri_options, errp);
834 if (r < 0) {
835 ret = r;
836 goto out;
839 r = connect_to_ssh(&s, uri_options,
840 LIBSSH2_FXF_READ|LIBSSH2_FXF_WRITE|
841 LIBSSH2_FXF_CREAT|LIBSSH2_FXF_TRUNC,
842 0644, errp);
843 if (r < 0) {
844 ret = r;
845 goto out;
848 if (total_size > 0) {
849 libssh2_sftp_seek64(s.sftp_handle, total_size-1);
850 r2 = libssh2_sftp_write(s.sftp_handle, c, 1);
851 if (r2 < 0) {
852 sftp_error_setg(errp, &s, "truncate failed");
853 ret = -EINVAL;
854 goto out;
856 s.attrs.filesize = total_size;
859 ret = 0;
861 out:
862 ssh_state_free(&s);
863 if (uri_options != NULL) {
864 QDECREF(uri_options);
866 return ret;
869 static void ssh_close(BlockDriverState *bs)
871 BDRVSSHState *s = bs->opaque;
873 ssh_state_free(s);
876 static int ssh_has_zero_init(BlockDriverState *bs)
878 BDRVSSHState *s = bs->opaque;
879 /* Assume false, unless we can positively prove it's true. */
880 int has_zero_init = 0;
882 if (s->attrs.flags & LIBSSH2_SFTP_ATTR_PERMISSIONS) {
883 if (s->attrs.permissions & LIBSSH2_SFTP_S_IFREG) {
884 has_zero_init = 1;
888 return has_zero_init;
891 static void restart_coroutine(void *opaque)
893 Coroutine *co = opaque;
895 DPRINTF("co=%p", co);
897 aio_co_wake(co);
900 /* A non-blocking call returned EAGAIN, so yield, ensuring the
901 * handlers are set up so that we'll be rescheduled when there is an
902 * interesting event on the socket.
904 static coroutine_fn void co_yield(BDRVSSHState *s, BlockDriverState *bs)
906 int r;
907 IOHandler *rd_handler = NULL, *wr_handler = NULL;
908 Coroutine *co = qemu_coroutine_self();
910 r = libssh2_session_block_directions(s->session);
912 if (r & LIBSSH2_SESSION_BLOCK_INBOUND) {
913 rd_handler = restart_coroutine;
915 if (r & LIBSSH2_SESSION_BLOCK_OUTBOUND) {
916 wr_handler = restart_coroutine;
919 DPRINTF("s->sock=%d rd_handler=%p wr_handler=%p", s->sock,
920 rd_handler, wr_handler);
922 aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock,
923 false, rd_handler, wr_handler, NULL, co);
924 qemu_coroutine_yield();
925 DPRINTF("s->sock=%d - back", s->sock);
926 aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock, false,
927 NULL, NULL, NULL, NULL);
930 /* SFTP has a function `libssh2_sftp_seek64' which seeks to a position
931 * in the remote file. Notice that it just updates a field in the
932 * sftp_handle structure, so there is no network traffic and it cannot
933 * fail.
935 * However, `libssh2_sftp_seek64' does have a catastrophic effect on
936 * performance since it causes the handle to throw away all in-flight
937 * reads and buffered readahead data. Therefore this function tries
938 * to be intelligent about when to call the underlying libssh2 function.
940 #define SSH_SEEK_WRITE 0
941 #define SSH_SEEK_READ 1
942 #define SSH_SEEK_FORCE 2
944 static void ssh_seek(BDRVSSHState *s, int64_t offset, int flags)
946 bool op_read = (flags & SSH_SEEK_READ) != 0;
947 bool force = (flags & SSH_SEEK_FORCE) != 0;
949 if (force || op_read != s->offset_op_read || offset != s->offset) {
950 DPRINTF("seeking to offset=%" PRIi64, offset);
951 libssh2_sftp_seek64(s->sftp_handle, offset);
952 s->offset = offset;
953 s->offset_op_read = op_read;
957 static coroutine_fn int ssh_read(BDRVSSHState *s, BlockDriverState *bs,
958 int64_t offset, size_t size,
959 QEMUIOVector *qiov)
961 ssize_t r;
962 size_t got;
963 char *buf, *end_of_vec;
964 struct iovec *i;
966 DPRINTF("offset=%" PRIi64 " size=%zu", offset, size);
968 ssh_seek(s, offset, SSH_SEEK_READ);
970 /* This keeps track of the current iovec element ('i'), where we
971 * will write to next ('buf'), and the end of the current iovec
972 * ('end_of_vec').
974 i = &qiov->iov[0];
975 buf = i->iov_base;
976 end_of_vec = i->iov_base + i->iov_len;
978 /* libssh2 has a hard-coded limit of 2000 bytes per request,
979 * although it will also do readahead behind our backs. Therefore
980 * we may have to do repeated reads here until we have read 'size'
981 * bytes.
983 for (got = 0; got < size; ) {
984 again:
985 DPRINTF("sftp_read buf=%p size=%zu", buf, end_of_vec - buf);
986 r = libssh2_sftp_read(s->sftp_handle, buf, end_of_vec - buf);
987 DPRINTF("sftp_read returned %zd", r);
989 if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
990 co_yield(s, bs);
991 goto again;
993 if (r < 0) {
994 sftp_error_report(s, "read failed");
995 s->offset = -1;
996 return -EIO;
998 if (r == 0) {
999 /* EOF: Short read so pad the buffer with zeroes and return it. */
1000 qemu_iovec_memset(qiov, got, 0, size - got);
1001 return 0;
1004 got += r;
1005 buf += r;
1006 s->offset += r;
1007 if (buf >= end_of_vec && got < size) {
1008 i++;
1009 buf = i->iov_base;
1010 end_of_vec = i->iov_base + i->iov_len;
1014 return 0;
1017 static coroutine_fn int ssh_co_readv(BlockDriverState *bs,
1018 int64_t sector_num,
1019 int nb_sectors, QEMUIOVector *qiov)
1021 BDRVSSHState *s = bs->opaque;
1022 int ret;
1024 qemu_co_mutex_lock(&s->lock);
1025 ret = ssh_read(s, bs, sector_num * BDRV_SECTOR_SIZE,
1026 nb_sectors * BDRV_SECTOR_SIZE, qiov);
1027 qemu_co_mutex_unlock(&s->lock);
1029 return ret;
1032 static int ssh_write(BDRVSSHState *s, BlockDriverState *bs,
1033 int64_t offset, size_t size,
1034 QEMUIOVector *qiov)
1036 ssize_t r;
1037 size_t written;
1038 char *buf, *end_of_vec;
1039 struct iovec *i;
1041 DPRINTF("offset=%" PRIi64 " size=%zu", offset, size);
1043 ssh_seek(s, offset, SSH_SEEK_WRITE);
1045 /* This keeps track of the current iovec element ('i'), where we
1046 * will read from next ('buf'), and the end of the current iovec
1047 * ('end_of_vec').
1049 i = &qiov->iov[0];
1050 buf = i->iov_base;
1051 end_of_vec = i->iov_base + i->iov_len;
1053 for (written = 0; written < size; ) {
1054 again:
1055 DPRINTF("sftp_write buf=%p size=%zu", buf, end_of_vec - buf);
1056 r = libssh2_sftp_write(s->sftp_handle, buf, end_of_vec - buf);
1057 DPRINTF("sftp_write returned %zd", r);
1059 if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
1060 co_yield(s, bs);
1061 goto again;
1063 if (r < 0) {
1064 sftp_error_report(s, "write failed");
1065 s->offset = -1;
1066 return -EIO;
1068 /* The libssh2 API is very unclear about this. A comment in
1069 * the code says "nothing was acked, and no EAGAIN was
1070 * received!" which apparently means that no data got sent
1071 * out, and the underlying channel didn't return any EAGAIN
1072 * indication. I think this is a bug in either libssh2 or
1073 * OpenSSH (server-side). In any case, forcing a seek (to
1074 * discard libssh2 internal buffers), and then trying again
1075 * works for me.
1077 if (r == 0) {
1078 ssh_seek(s, offset + written, SSH_SEEK_WRITE|SSH_SEEK_FORCE);
1079 co_yield(s, bs);
1080 goto again;
1083 written += r;
1084 buf += r;
1085 s->offset += r;
1086 if (buf >= end_of_vec && written < size) {
1087 i++;
1088 buf = i->iov_base;
1089 end_of_vec = i->iov_base + i->iov_len;
1092 if (offset + written > s->attrs.filesize)
1093 s->attrs.filesize = offset + written;
1096 return 0;
1099 static coroutine_fn int ssh_co_writev(BlockDriverState *bs,
1100 int64_t sector_num,
1101 int nb_sectors, QEMUIOVector *qiov)
1103 BDRVSSHState *s = bs->opaque;
1104 int ret;
1106 qemu_co_mutex_lock(&s->lock);
1107 ret = ssh_write(s, bs, sector_num * BDRV_SECTOR_SIZE,
1108 nb_sectors * BDRV_SECTOR_SIZE, qiov);
1109 qemu_co_mutex_unlock(&s->lock);
1111 return ret;
1114 static void unsafe_flush_warning(BDRVSSHState *s, const char *what)
1116 if (!s->unsafe_flush_warning) {
1117 error_report("warning: ssh server %s does not support fsync",
1118 s->inet->host);
1119 if (what) {
1120 error_report("to support fsync, you need %s", what);
1122 s->unsafe_flush_warning = true;
1126 #ifdef HAS_LIBSSH2_SFTP_FSYNC
1128 static coroutine_fn int ssh_flush(BDRVSSHState *s, BlockDriverState *bs)
1130 int r;
1132 DPRINTF("fsync");
1133 again:
1134 r = libssh2_sftp_fsync(s->sftp_handle);
1135 if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
1136 co_yield(s, bs);
1137 goto again;
1139 if (r == LIBSSH2_ERROR_SFTP_PROTOCOL &&
1140 libssh2_sftp_last_error(s->sftp) == LIBSSH2_FX_OP_UNSUPPORTED) {
1141 unsafe_flush_warning(s, "OpenSSH >= 6.3");
1142 return 0;
1144 if (r < 0) {
1145 sftp_error_report(s, "fsync failed");
1146 return -EIO;
1149 return 0;
1152 static coroutine_fn int ssh_co_flush(BlockDriverState *bs)
1154 BDRVSSHState *s = bs->opaque;
1155 int ret;
1157 qemu_co_mutex_lock(&s->lock);
1158 ret = ssh_flush(s, bs);
1159 qemu_co_mutex_unlock(&s->lock);
1161 return ret;
1164 #else /* !HAS_LIBSSH2_SFTP_FSYNC */
1166 static coroutine_fn int ssh_co_flush(BlockDriverState *bs)
1168 BDRVSSHState *s = bs->opaque;
1170 unsafe_flush_warning(s, "libssh2 >= 1.4.4");
1171 return 0;
1174 #endif /* !HAS_LIBSSH2_SFTP_FSYNC */
1176 static int64_t ssh_getlength(BlockDriverState *bs)
1178 BDRVSSHState *s = bs->opaque;
1179 int64_t length;
1181 /* Note we cannot make a libssh2 call here. */
1182 length = (int64_t) s->attrs.filesize;
1183 DPRINTF("length=%" PRIi64, length);
1185 return length;
1188 static BlockDriver bdrv_ssh = {
1189 .format_name = "ssh",
1190 .protocol_name = "ssh",
1191 .instance_size = sizeof(BDRVSSHState),
1192 .bdrv_parse_filename = ssh_parse_filename,
1193 .bdrv_file_open = ssh_file_open,
1194 .bdrv_create = ssh_create,
1195 .bdrv_close = ssh_close,
1196 .bdrv_has_zero_init = ssh_has_zero_init,
1197 .bdrv_co_readv = ssh_co_readv,
1198 .bdrv_co_writev = ssh_co_writev,
1199 .bdrv_getlength = ssh_getlength,
1200 .bdrv_co_flush_to_disk = ssh_co_flush,
1201 .create_opts = &ssh_create_opts,
1204 static void bdrv_ssh_init(void)
1206 int r;
1208 r = libssh2_init(0);
1209 if (r != 0) {
1210 fprintf(stderr, "libssh2 initialization failed, %d\n", r);
1211 exit(EXIT_FAILURE);
1214 bdrv_register(&bdrv_ssh);
1217 block_init(bdrv_ssh_init);