target-arm: A64: Fix a typo when declaring TLBI ops
[qemu.git] / block / ssh.c
blobaa63c9d20ee3eedd6714c1bcdba7285c6a3fc366
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 <stdio.h>
26 #include <stdlib.h>
27 #include <stdarg.h>
29 #include <libssh2.h>
30 #include <libssh2_sftp.h>
32 #include "block/block_int.h"
33 #include "qemu/sockets.h"
34 #include "qemu/uri.h"
35 #include "qapi/qmp/qint.h"
37 /* DEBUG_SSH=1 enables the DPRINTF (debugging printf) statements in
38 * this block driver code.
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
46 #define DEBUG_SSH 0
47 #define TRACE_LIBSSH2 0 /* or try: LIBSSH2_TRACE_SFTP */
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)
57 typedef struct BDRVSSHState {
58 /* Coroutine. */
59 CoMutex lock;
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 */
67 /* See ssh_seek() function below. */
68 int64_t offset;
69 bool offset_op_read;
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).
74 LIBSSH2_SFTP_ATTRIBUTES attrs;
76 /* Used to warn if 'flush' is not supported. */
77 char *hostport;
78 bool unsafe_flush_warning;
79 } BDRVSSHState;
81 static void ssh_state_init(BDRVSSHState *s)
83 memset(s, 0, sizeof *s);
84 s->sock = -1;
85 s->offset = -1;
86 qemu_co_mutex_init(&s->lock);
89 static void ssh_state_free(BDRVSSHState *s)
91 g_free(s->hostport);
92 if (s->sftp_handle) {
93 libssh2_sftp_close(s->sftp_handle);
95 if (s->sftp) {
96 libssh2_sftp_shutdown(s->sftp);
98 if (s->session) {
99 libssh2_session_disconnect(s->session,
100 "from qemu ssh client: "
101 "user closed the connection");
102 libssh2_session_free(s->session);
104 if (s->sock >= 0) {
105 close(s->sock);
109 /* Wrappers around error_report which make sure to dump as much
110 * information from libssh2 as possible.
112 static void GCC_FMT_ATTR(2, 3)
113 session_error_report(BDRVSSHState *s, const char *fs, ...)
115 va_list args;
117 va_start(args, fs);
118 error_vprintf(fs, args);
120 if ((s)->session) {
121 char *ssh_err;
122 int ssh_err_code;
124 libssh2_session_last_error((s)->session, &ssh_err, NULL, 0);
125 /* This is not an errno. See <libssh2.h>. */
126 ssh_err_code = libssh2_session_last_errno((s)->session);
128 error_printf(": %s (libssh2 error code: %d)", ssh_err, ssh_err_code);
131 va_end(args);
132 error_printf("\n");
135 static void GCC_FMT_ATTR(2, 3)
136 sftp_error_report(BDRVSSHState *s, const char *fs, ...)
138 va_list args;
140 va_start(args, fs);
141 error_vprintf(fs, args);
143 if ((s)->sftp) {
144 char *ssh_err;
145 int ssh_err_code;
146 unsigned long sftp_err_code;
148 libssh2_session_last_error((s)->session, &ssh_err, NULL, 0);
149 /* This is not an errno. See <libssh2.h>. */
150 ssh_err_code = libssh2_session_last_errno((s)->session);
151 /* See <libssh2_sftp.h>. */
152 sftp_err_code = libssh2_sftp_last_error((s)->sftp);
154 error_printf(": %s (libssh2 error code: %d, sftp error code: %lu)",
155 ssh_err, ssh_err_code, sftp_err_code);
158 va_end(args);
159 error_printf("\n");
162 static int parse_uri(const char *filename, QDict *options, Error **errp)
164 URI *uri = NULL;
165 QueryParams *qp = NULL;
166 int i;
168 uri = uri_parse(filename);
169 if (!uri) {
170 return -EINVAL;
173 if (strcmp(uri->scheme, "ssh") != 0) {
174 error_setg(errp, "URI scheme must be 'ssh'");
175 goto err;
178 if (!uri->server || strcmp(uri->server, "") == 0) {
179 error_setg(errp, "missing hostname in URI");
180 goto err;
183 if (!uri->path || strcmp(uri->path, "") == 0) {
184 error_setg(errp, "missing remote path in URI");
185 goto err;
188 qp = query_params_parse(uri->query);
189 if (!qp) {
190 error_setg(errp, "could not parse query parameters");
191 goto err;
194 if(uri->user && strcmp(uri->user, "") != 0) {
195 qdict_put(options, "user", qstring_from_str(uri->user));
198 qdict_put(options, "host", qstring_from_str(uri->server));
200 if (uri->port) {
201 qdict_put(options, "port", qint_from_int(uri->port));
204 qdict_put(options, "path", qstring_from_str(uri->path));
206 /* Pick out any query parameters that we understand, and ignore
207 * the rest.
209 for (i = 0; i < qp->n; ++i) {
210 if (strcmp(qp->p[i].name, "host_key_check") == 0) {
211 qdict_put(options, "host_key_check",
212 qstring_from_str(qp->p[i].value));
216 query_params_free(qp);
217 uri_free(uri);
218 return 0;
220 err:
221 if (qp) {
222 query_params_free(qp);
224 if (uri) {
225 uri_free(uri);
227 return -EINVAL;
230 static void ssh_parse_filename(const char *filename, QDict *options,
231 Error **errp)
233 if (qdict_haskey(options, "user") ||
234 qdict_haskey(options, "host") ||
235 qdict_haskey(options, "port") ||
236 qdict_haskey(options, "path") ||
237 qdict_haskey(options, "host_key_check")) {
238 error_setg(errp, "user, host, port, path, host_key_check cannot be used at the same time as a file option");
239 return;
242 parse_uri(filename, options, errp);
245 static int check_host_key_knownhosts(BDRVSSHState *s,
246 const char *host, int port)
248 const char *home;
249 char *knh_file = NULL;
250 LIBSSH2_KNOWNHOSTS *knh = NULL;
251 struct libssh2_knownhost *found;
252 int ret, r;
253 const char *hostkey;
254 size_t len;
255 int type;
257 hostkey = libssh2_session_hostkey(s->session, &len, &type);
258 if (!hostkey) {
259 ret = -EINVAL;
260 session_error_report(s, "failed to read remote host key");
261 goto out;
264 knh = libssh2_knownhost_init(s->session);
265 if (!knh) {
266 ret = -EINVAL;
267 session_error_report(s, "failed to initialize known hosts support");
268 goto out;
271 home = getenv("HOME");
272 if (home) {
273 knh_file = g_strdup_printf("%s/.ssh/known_hosts", home);
274 } else {
275 knh_file = g_strdup_printf("/root/.ssh/known_hosts");
278 /* Read all known hosts from OpenSSH-style known_hosts file. */
279 libssh2_knownhost_readfile(knh, knh_file, LIBSSH2_KNOWNHOST_FILE_OPENSSH);
281 r = libssh2_knownhost_checkp(knh, host, port, hostkey, len,
282 LIBSSH2_KNOWNHOST_TYPE_PLAIN|
283 LIBSSH2_KNOWNHOST_KEYENC_RAW,
284 &found);
285 switch (r) {
286 case LIBSSH2_KNOWNHOST_CHECK_MATCH:
287 /* OK */
288 DPRINTF("host key OK: %s", found->key);
289 break;
290 case LIBSSH2_KNOWNHOST_CHECK_MISMATCH:
291 ret = -EINVAL;
292 session_error_report(s, "host key does not match the one in known_hosts (found key %s)",
293 found->key);
294 goto out;
295 case LIBSSH2_KNOWNHOST_CHECK_NOTFOUND:
296 ret = -EINVAL;
297 session_error_report(s, "no host key was found in known_hosts");
298 goto out;
299 case LIBSSH2_KNOWNHOST_CHECK_FAILURE:
300 ret = -EINVAL;
301 session_error_report(s, "failure matching the host key with known_hosts");
302 goto out;
303 default:
304 ret = -EINVAL;
305 session_error_report(s, "unknown error matching the host key with known_hosts (%d)",
307 goto out;
310 /* known_hosts checking successful. */
311 ret = 0;
313 out:
314 if (knh != NULL) {
315 libssh2_knownhost_free(knh);
317 g_free(knh_file);
318 return ret;
321 static unsigned hex2decimal(char ch)
323 if (ch >= '0' && ch <= '9') {
324 return (ch - '0');
325 } else if (ch >= 'a' && ch <= 'f') {
326 return 10 + (ch - 'a');
327 } else if (ch >= 'A' && ch <= 'F') {
328 return 10 + (ch - 'A');
331 return -1;
334 /* Compare the binary fingerprint (hash of host key) with the
335 * host_key_check parameter.
337 static int compare_fingerprint(const unsigned char *fingerprint, size_t len,
338 const char *host_key_check)
340 unsigned c;
342 while (len > 0) {
343 while (*host_key_check == ':')
344 host_key_check++;
345 if (!qemu_isxdigit(host_key_check[0]) ||
346 !qemu_isxdigit(host_key_check[1]))
347 return 1;
348 c = hex2decimal(host_key_check[0]) * 16 +
349 hex2decimal(host_key_check[1]);
350 if (c - *fingerprint != 0)
351 return c - *fingerprint;
352 fingerprint++;
353 len--;
354 host_key_check += 2;
356 return *host_key_check - '\0';
359 static int
360 check_host_key_hash(BDRVSSHState *s, const char *hash,
361 int hash_type, size_t fingerprint_len)
363 const char *fingerprint;
365 fingerprint = libssh2_hostkey_hash(s->session, hash_type);
366 if (!fingerprint) {
367 session_error_report(s, "failed to read remote host key");
368 return -EINVAL;
371 if(compare_fingerprint((unsigned char *) fingerprint, fingerprint_len,
372 hash) != 0) {
373 error_report("remote host key does not match host_key_check '%s'",
374 hash);
375 return -EPERM;
378 return 0;
381 static int check_host_key(BDRVSSHState *s, const char *host, int port,
382 const char *host_key_check)
384 /* host_key_check=no */
385 if (strcmp(host_key_check, "no") == 0) {
386 return 0;
389 /* host_key_check=md5:xx:yy:zz:... */
390 if (strncmp(host_key_check, "md5:", 4) == 0) {
391 return check_host_key_hash(s, &host_key_check[4],
392 LIBSSH2_HOSTKEY_HASH_MD5, 16);
395 /* host_key_check=sha1:xx:yy:zz:... */
396 if (strncmp(host_key_check, "sha1:", 5) == 0) {
397 return check_host_key_hash(s, &host_key_check[5],
398 LIBSSH2_HOSTKEY_HASH_SHA1, 20);
401 /* host_key_check=yes */
402 if (strcmp(host_key_check, "yes") == 0) {
403 return check_host_key_knownhosts(s, host, port);
406 error_report("unknown host_key_check setting (%s)", host_key_check);
407 return -EINVAL;
410 static int authenticate(BDRVSSHState *s, const char *user)
412 int r, ret;
413 const char *userauthlist;
414 LIBSSH2_AGENT *agent = NULL;
415 struct libssh2_agent_publickey *identity;
416 struct libssh2_agent_publickey *prev_identity = NULL;
418 userauthlist = libssh2_userauth_list(s->session, user, strlen(user));
419 if (strstr(userauthlist, "publickey") == NULL) {
420 ret = -EPERM;
421 error_report("remote server does not support \"publickey\" authentication");
422 goto out;
425 /* Connect to ssh-agent and try each identity in turn. */
426 agent = libssh2_agent_init(s->session);
427 if (!agent) {
428 ret = -EINVAL;
429 session_error_report(s, "failed to initialize ssh-agent support");
430 goto out;
432 if (libssh2_agent_connect(agent)) {
433 ret = -ECONNREFUSED;
434 session_error_report(s, "failed to connect to ssh-agent");
435 goto out;
437 if (libssh2_agent_list_identities(agent)) {
438 ret = -EINVAL;
439 session_error_report(s, "failed requesting identities from ssh-agent");
440 goto out;
443 for(;;) {
444 r = libssh2_agent_get_identity(agent, &identity, prev_identity);
445 if (r == 1) { /* end of list */
446 break;
448 if (r < 0) {
449 ret = -EINVAL;
450 session_error_report(s, "failed to obtain identity from ssh-agent");
451 goto out;
453 r = libssh2_agent_userauth(agent, user, identity);
454 if (r == 0) {
455 /* Authenticated! */
456 ret = 0;
457 goto out;
459 /* Failed to authenticate with this identity, try the next one. */
460 prev_identity = identity;
463 ret = -EPERM;
464 error_report("failed to authenticate using publickey authentication "
465 "and the identities held by your ssh-agent");
467 out:
468 if (agent != NULL) {
469 /* Note: libssh2 implementation implicitly calls
470 * libssh2_agent_disconnect if necessary.
472 libssh2_agent_free(agent);
475 return ret;
478 static int connect_to_ssh(BDRVSSHState *s, QDict *options,
479 int ssh_flags, int creat_mode)
481 int r, ret;
482 Error *err = NULL;
483 const char *host, *user, *path, *host_key_check;
484 int port;
486 host = qdict_get_str(options, "host");
488 if (qdict_haskey(options, "port")) {
489 port = qdict_get_int(options, "port");
490 } else {
491 port = 22;
494 path = qdict_get_str(options, "path");
496 if (qdict_haskey(options, "user")) {
497 user = qdict_get_str(options, "user");
498 } else {
499 user = g_get_user_name();
500 if (!user) {
501 ret = -errno;
502 goto err;
506 if (qdict_haskey(options, "host_key_check")) {
507 host_key_check = qdict_get_str(options, "host_key_check");
508 } else {
509 host_key_check = "yes";
512 /* Construct the host:port name for inet_connect. */
513 g_free(s->hostport);
514 s->hostport = g_strdup_printf("%s:%d", host, port);
516 /* Open the socket and connect. */
517 s->sock = inet_connect(s->hostport, &err);
518 if (err != NULL) {
519 ret = -errno;
520 qerror_report_err(err);
521 error_free(err);
522 goto err;
525 /* Create SSH session. */
526 s->session = libssh2_session_init();
527 if (!s->session) {
528 ret = -EINVAL;
529 session_error_report(s, "failed to initialize libssh2 session");
530 goto err;
533 #if TRACE_LIBSSH2 != 0
534 libssh2_trace(s->session, TRACE_LIBSSH2);
535 #endif
537 r = libssh2_session_handshake(s->session, s->sock);
538 if (r != 0) {
539 ret = -EINVAL;
540 session_error_report(s, "failed to establish SSH session");
541 goto err;
544 /* Check the remote host's key against known_hosts. */
545 ret = check_host_key(s, host, port, host_key_check);
546 if (ret < 0) {
547 goto err;
550 /* Authenticate. */
551 ret = authenticate(s, user);
552 if (ret < 0) {
553 goto err;
556 /* Start SFTP. */
557 s->sftp = libssh2_sftp_init(s->session);
558 if (!s->sftp) {
559 session_error_report(s, "failed to initialize sftp handle");
560 ret = -EINVAL;
561 goto err;
564 /* Open the remote file. */
565 DPRINTF("opening file %s flags=0x%x creat_mode=0%o",
566 path, ssh_flags, creat_mode);
567 s->sftp_handle = libssh2_sftp_open(s->sftp, path, ssh_flags, creat_mode);
568 if (!s->sftp_handle) {
569 session_error_report(s, "failed to open remote file '%s'", path);
570 ret = -EINVAL;
571 goto err;
574 r = libssh2_sftp_fstat(s->sftp_handle, &s->attrs);
575 if (r < 0) {
576 sftp_error_report(s, "failed to read file attributes");
577 return -EINVAL;
580 /* Delete the options we've used; any not deleted will cause the
581 * block layer to give an error about unused options.
583 qdict_del(options, "host");
584 qdict_del(options, "port");
585 qdict_del(options, "user");
586 qdict_del(options, "path");
587 qdict_del(options, "host_key_check");
589 return 0;
591 err:
592 if (s->sftp_handle) {
593 libssh2_sftp_close(s->sftp_handle);
595 s->sftp_handle = NULL;
596 if (s->sftp) {
597 libssh2_sftp_shutdown(s->sftp);
599 s->sftp = NULL;
600 if (s->session) {
601 libssh2_session_disconnect(s->session,
602 "from qemu ssh client: "
603 "error opening connection");
604 libssh2_session_free(s->session);
606 s->session = NULL;
608 return ret;
611 static int ssh_file_open(BlockDriverState *bs, QDict *options, int bdrv_flags,
612 Error **errp)
614 BDRVSSHState *s = bs->opaque;
615 int ret;
616 int ssh_flags;
618 ssh_state_init(s);
620 ssh_flags = LIBSSH2_FXF_READ;
621 if (bdrv_flags & BDRV_O_RDWR) {
622 ssh_flags |= LIBSSH2_FXF_WRITE;
625 /* Start up SSH. */
626 ret = connect_to_ssh(s, options, ssh_flags, 0);
627 if (ret < 0) {
628 goto err;
631 /* Go non-blocking. */
632 libssh2_session_set_blocking(s->session, 0);
634 return 0;
636 err:
637 if (s->sock >= 0) {
638 close(s->sock);
640 s->sock = -1;
642 return ret;
645 static QEMUOptionParameter ssh_create_options[] = {
647 .name = BLOCK_OPT_SIZE,
648 .type = OPT_SIZE,
649 .help = "Virtual disk size"
651 { NULL }
654 static int ssh_create(const char *filename, QEMUOptionParameter *options,
655 Error **errp)
657 int r, ret;
658 Error *local_err = NULL;
659 int64_t total_size = 0;
660 QDict *uri_options = NULL;
661 BDRVSSHState s;
662 ssize_t r2;
663 char c[1] = { '\0' };
665 ssh_state_init(&s);
667 /* Get desired file size. */
668 while (options && options->name) {
669 if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
670 total_size = options->value.n;
672 options++;
674 DPRINTF("total_size=%" PRIi64, total_size);
676 uri_options = qdict_new();
677 r = parse_uri(filename, uri_options, &local_err);
678 if (r < 0) {
679 qerror_report_err(local_err);
680 error_free(local_err);
681 ret = r;
682 goto out;
685 r = connect_to_ssh(&s, uri_options,
686 LIBSSH2_FXF_READ|LIBSSH2_FXF_WRITE|
687 LIBSSH2_FXF_CREAT|LIBSSH2_FXF_TRUNC, 0644);
688 if (r < 0) {
689 ret = r;
690 goto out;
693 if (total_size > 0) {
694 libssh2_sftp_seek64(s.sftp_handle, total_size-1);
695 r2 = libssh2_sftp_write(s.sftp_handle, c, 1);
696 if (r2 < 0) {
697 sftp_error_report(&s, "truncate failed");
698 ret = -EINVAL;
699 goto out;
701 s.attrs.filesize = total_size;
704 ret = 0;
706 out:
707 ssh_state_free(&s);
708 if (uri_options != NULL) {
709 QDECREF(uri_options);
711 return ret;
714 static void ssh_close(BlockDriverState *bs)
716 BDRVSSHState *s = bs->opaque;
718 ssh_state_free(s);
721 static int ssh_has_zero_init(BlockDriverState *bs)
723 BDRVSSHState *s = bs->opaque;
724 /* Assume false, unless we can positively prove it's true. */
725 int has_zero_init = 0;
727 if (s->attrs.flags & LIBSSH2_SFTP_ATTR_PERMISSIONS) {
728 if (s->attrs.permissions & LIBSSH2_SFTP_S_IFREG) {
729 has_zero_init = 1;
733 return has_zero_init;
736 static void restart_coroutine(void *opaque)
738 Coroutine *co = opaque;
740 DPRINTF("co=%p", co);
742 qemu_coroutine_enter(co, NULL);
745 static coroutine_fn void set_fd_handler(BDRVSSHState *s)
747 int r;
748 IOHandler *rd_handler = NULL, *wr_handler = NULL;
749 Coroutine *co = qemu_coroutine_self();
751 r = libssh2_session_block_directions(s->session);
753 if (r & LIBSSH2_SESSION_BLOCK_INBOUND) {
754 rd_handler = restart_coroutine;
756 if (r & LIBSSH2_SESSION_BLOCK_OUTBOUND) {
757 wr_handler = restart_coroutine;
760 DPRINTF("s->sock=%d rd_handler=%p wr_handler=%p", s->sock,
761 rd_handler, wr_handler);
763 qemu_aio_set_fd_handler(s->sock, rd_handler, wr_handler, co);
766 static coroutine_fn void clear_fd_handler(BDRVSSHState *s)
768 DPRINTF("s->sock=%d", s->sock);
769 qemu_aio_set_fd_handler(s->sock, NULL, NULL, NULL);
772 /* A non-blocking call returned EAGAIN, so yield, ensuring the
773 * handlers are set up so that we'll be rescheduled when there is an
774 * interesting event on the socket.
776 static coroutine_fn void co_yield(BDRVSSHState *s)
778 set_fd_handler(s);
779 qemu_coroutine_yield();
780 clear_fd_handler(s);
783 /* SFTP has a function `libssh2_sftp_seek64' which seeks to a position
784 * in the remote file. Notice that it just updates a field in the
785 * sftp_handle structure, so there is no network traffic and it cannot
786 * fail.
788 * However, `libssh2_sftp_seek64' does have a catastrophic effect on
789 * performance since it causes the handle to throw away all in-flight
790 * reads and buffered readahead data. Therefore this function tries
791 * to be intelligent about when to call the underlying libssh2 function.
793 #define SSH_SEEK_WRITE 0
794 #define SSH_SEEK_READ 1
795 #define SSH_SEEK_FORCE 2
797 static void ssh_seek(BDRVSSHState *s, int64_t offset, int flags)
799 bool op_read = (flags & SSH_SEEK_READ) != 0;
800 bool force = (flags & SSH_SEEK_FORCE) != 0;
802 if (force || op_read != s->offset_op_read || offset != s->offset) {
803 DPRINTF("seeking to offset=%" PRIi64, offset);
804 libssh2_sftp_seek64(s->sftp_handle, offset);
805 s->offset = offset;
806 s->offset_op_read = op_read;
810 static coroutine_fn int ssh_read(BDRVSSHState *s,
811 int64_t offset, size_t size,
812 QEMUIOVector *qiov)
814 ssize_t r;
815 size_t got;
816 char *buf, *end_of_vec;
817 struct iovec *i;
819 DPRINTF("offset=%" PRIi64 " size=%zu", offset, size);
821 ssh_seek(s, offset, SSH_SEEK_READ);
823 /* This keeps track of the current iovec element ('i'), where we
824 * will write to next ('buf'), and the end of the current iovec
825 * ('end_of_vec').
827 i = &qiov->iov[0];
828 buf = i->iov_base;
829 end_of_vec = i->iov_base + i->iov_len;
831 /* libssh2 has a hard-coded limit of 2000 bytes per request,
832 * although it will also do readahead behind our backs. Therefore
833 * we may have to do repeated reads here until we have read 'size'
834 * bytes.
836 for (got = 0; got < size; ) {
837 again:
838 DPRINTF("sftp_read buf=%p size=%zu", buf, end_of_vec - buf);
839 r = libssh2_sftp_read(s->sftp_handle, buf, end_of_vec - buf);
840 DPRINTF("sftp_read returned %zd", r);
842 if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
843 co_yield(s);
844 goto again;
846 if (r < 0) {
847 sftp_error_report(s, "read failed");
848 s->offset = -1;
849 return -EIO;
851 if (r == 0) {
852 /* EOF: Short read so pad the buffer with zeroes and return it. */
853 qemu_iovec_memset(qiov, got, 0, size - got);
854 return 0;
857 got += r;
858 buf += r;
859 s->offset += r;
860 if (buf >= end_of_vec && got < size) {
861 i++;
862 buf = i->iov_base;
863 end_of_vec = i->iov_base + i->iov_len;
867 return 0;
870 static coroutine_fn int ssh_co_readv(BlockDriverState *bs,
871 int64_t sector_num,
872 int nb_sectors, QEMUIOVector *qiov)
874 BDRVSSHState *s = bs->opaque;
875 int ret;
877 qemu_co_mutex_lock(&s->lock);
878 ret = ssh_read(s, sector_num * BDRV_SECTOR_SIZE,
879 nb_sectors * BDRV_SECTOR_SIZE, qiov);
880 qemu_co_mutex_unlock(&s->lock);
882 return ret;
885 static int ssh_write(BDRVSSHState *s,
886 int64_t offset, size_t size,
887 QEMUIOVector *qiov)
889 ssize_t r;
890 size_t written;
891 char *buf, *end_of_vec;
892 struct iovec *i;
894 DPRINTF("offset=%" PRIi64 " size=%zu", offset, size);
896 ssh_seek(s, offset, SSH_SEEK_WRITE);
898 /* This keeps track of the current iovec element ('i'), where we
899 * will read from next ('buf'), and the end of the current iovec
900 * ('end_of_vec').
902 i = &qiov->iov[0];
903 buf = i->iov_base;
904 end_of_vec = i->iov_base + i->iov_len;
906 for (written = 0; written < size; ) {
907 again:
908 DPRINTF("sftp_write buf=%p size=%zu", buf, end_of_vec - buf);
909 r = libssh2_sftp_write(s->sftp_handle, buf, end_of_vec - buf);
910 DPRINTF("sftp_write returned %zd", r);
912 if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
913 co_yield(s);
914 goto again;
916 if (r < 0) {
917 sftp_error_report(s, "write failed");
918 s->offset = -1;
919 return -EIO;
921 /* The libssh2 API is very unclear about this. A comment in
922 * the code says "nothing was acked, and no EAGAIN was
923 * received!" which apparently means that no data got sent
924 * out, and the underlying channel didn't return any EAGAIN
925 * indication. I think this is a bug in either libssh2 or
926 * OpenSSH (server-side). In any case, forcing a seek (to
927 * discard libssh2 internal buffers), and then trying again
928 * works for me.
930 if (r == 0) {
931 ssh_seek(s, offset + written, SSH_SEEK_WRITE|SSH_SEEK_FORCE);
932 co_yield(s);
933 goto again;
936 written += r;
937 buf += r;
938 s->offset += r;
939 if (buf >= end_of_vec && written < size) {
940 i++;
941 buf = i->iov_base;
942 end_of_vec = i->iov_base + i->iov_len;
945 if (offset + written > s->attrs.filesize)
946 s->attrs.filesize = offset + written;
949 return 0;
952 static coroutine_fn int ssh_co_writev(BlockDriverState *bs,
953 int64_t sector_num,
954 int nb_sectors, QEMUIOVector *qiov)
956 BDRVSSHState *s = bs->opaque;
957 int ret;
959 qemu_co_mutex_lock(&s->lock);
960 ret = ssh_write(s, sector_num * BDRV_SECTOR_SIZE,
961 nb_sectors * BDRV_SECTOR_SIZE, qiov);
962 qemu_co_mutex_unlock(&s->lock);
964 return ret;
967 static void unsafe_flush_warning(BDRVSSHState *s, const char *what)
969 if (!s->unsafe_flush_warning) {
970 error_report("warning: ssh server %s does not support fsync",
971 s->hostport);
972 if (what) {
973 error_report("to support fsync, you need %s", what);
975 s->unsafe_flush_warning = true;
979 #ifdef HAS_LIBSSH2_SFTP_FSYNC
981 static coroutine_fn int ssh_flush(BDRVSSHState *s)
983 int r;
985 DPRINTF("fsync");
986 again:
987 r = libssh2_sftp_fsync(s->sftp_handle);
988 if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
989 co_yield(s);
990 goto again;
992 if (r == LIBSSH2_ERROR_SFTP_PROTOCOL &&
993 libssh2_sftp_last_error(s->sftp) == LIBSSH2_FX_OP_UNSUPPORTED) {
994 unsafe_flush_warning(s, "OpenSSH >= 6.3");
995 return 0;
997 if (r < 0) {
998 sftp_error_report(s, "fsync failed");
999 return -EIO;
1002 return 0;
1005 static coroutine_fn int ssh_co_flush(BlockDriverState *bs)
1007 BDRVSSHState *s = bs->opaque;
1008 int ret;
1010 qemu_co_mutex_lock(&s->lock);
1011 ret = ssh_flush(s);
1012 qemu_co_mutex_unlock(&s->lock);
1014 return ret;
1017 #else /* !HAS_LIBSSH2_SFTP_FSYNC */
1019 static coroutine_fn int ssh_co_flush(BlockDriverState *bs)
1021 BDRVSSHState *s = bs->opaque;
1023 unsafe_flush_warning(s, "libssh2 >= 1.4.4");
1024 return 0;
1027 #endif /* !HAS_LIBSSH2_SFTP_FSYNC */
1029 static int64_t ssh_getlength(BlockDriverState *bs)
1031 BDRVSSHState *s = bs->opaque;
1032 int64_t length;
1034 /* Note we cannot make a libssh2 call here. */
1035 length = (int64_t) s->attrs.filesize;
1036 DPRINTF("length=%" PRIi64, length);
1038 return length;
1041 static BlockDriver bdrv_ssh = {
1042 .format_name = "ssh",
1043 .protocol_name = "ssh",
1044 .instance_size = sizeof(BDRVSSHState),
1045 .bdrv_parse_filename = ssh_parse_filename,
1046 .bdrv_file_open = ssh_file_open,
1047 .bdrv_create = ssh_create,
1048 .bdrv_close = ssh_close,
1049 .bdrv_has_zero_init = ssh_has_zero_init,
1050 .bdrv_co_readv = ssh_co_readv,
1051 .bdrv_co_writev = ssh_co_writev,
1052 .bdrv_getlength = ssh_getlength,
1053 .bdrv_co_flush_to_disk = ssh_co_flush,
1054 .create_options = ssh_create_options,
1057 static void bdrv_ssh_init(void)
1059 int r;
1061 r = libssh2_init(0);
1062 if (r != 0) {
1063 fprintf(stderr, "libssh2 initialization failed, %d\n", r);
1064 exit(EXIT_FAILURE);
1067 bdrv_register(&bdrv_ssh);
1070 block_init(bdrv_ssh_init);