vmxnet3: Drop net_vmxnet3_info.can_receive
[qemu.git] / block / ssh.c
blob8d0673903d37847b4827e4dabc1ad74a169a6cef
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/error-report.h"
34 #include "qemu/sockets.h"
35 #include "qemu/uri.h"
36 #include "qapi/qmp/qint.h"
37 #include "qapi/qmp/qstring.h"
39 /* DEBUG_SSH=1 enables the DPRINTF (debugging printf) statements in
40 * this block driver code.
42 * TRACE_LIBSSH2=<bitmask> enables tracing in libssh2 itself. Note
43 * that this requires that libssh2 was specially compiled with the
44 * `./configure --enable-debug' option, so most likely you will have
45 * to compile it yourself. The meaning of <bitmask> is described
46 * here: http://www.libssh2.org/libssh2_trace.html
48 #define DEBUG_SSH 0
49 #define TRACE_LIBSSH2 0 /* or try: LIBSSH2_TRACE_SFTP */
51 #define DPRINTF(fmt, ...) \
52 do { \
53 if (DEBUG_SSH) { \
54 fprintf(stderr, "ssh: %-15s " fmt "\n", \
55 __func__, ##__VA_ARGS__); \
56 } \
57 } while (0)
59 typedef struct BDRVSSHState {
60 /* Coroutine. */
61 CoMutex lock;
63 /* SSH connection. */
64 int sock; /* socket */
65 LIBSSH2_SESSION *session; /* ssh session */
66 LIBSSH2_SFTP *sftp; /* sftp session */
67 LIBSSH2_SFTP_HANDLE *sftp_handle; /* sftp remote file handle */
69 /* See ssh_seek() function below. */
70 int64_t offset;
71 bool offset_op_read;
73 /* File attributes at open. We try to keep the .filesize field
74 * updated if it changes (eg by writing at the end of the file).
76 LIBSSH2_SFTP_ATTRIBUTES attrs;
78 /* Used to warn if 'flush' is not supported. */
79 char *hostport;
80 bool unsafe_flush_warning;
81 } BDRVSSHState;
83 static void ssh_state_init(BDRVSSHState *s)
85 memset(s, 0, sizeof *s);
86 s->sock = -1;
87 s->offset = -1;
88 qemu_co_mutex_init(&s->lock);
91 static void ssh_state_free(BDRVSSHState *s)
93 g_free(s->hostport);
94 if (s->sftp_handle) {
95 libssh2_sftp_close(s->sftp_handle);
97 if (s->sftp) {
98 libssh2_sftp_shutdown(s->sftp);
100 if (s->session) {
101 libssh2_session_disconnect(s->session,
102 "from qemu ssh client: "
103 "user closed the connection");
104 libssh2_session_free(s->session);
106 if (s->sock >= 0) {
107 close(s->sock);
111 static void GCC_FMT_ATTR(3, 4)
112 session_error_setg(Error **errp, BDRVSSHState *s, const char *fs, ...)
114 va_list args;
115 char *msg;
117 va_start(args, fs);
118 msg = g_strdup_vprintf(fs, args);
119 va_end(args);
121 if (s->session) {
122 char *ssh_err;
123 int ssh_err_code;
125 /* This is not an errno. See <libssh2.h>. */
126 ssh_err_code = libssh2_session_last_error(s->session,
127 &ssh_err, NULL, 0);
128 error_setg(errp, "%s: %s (libssh2 error code: %d)",
129 msg, ssh_err, ssh_err_code);
130 } else {
131 error_setg(errp, "%s", msg);
133 g_free(msg);
136 static void GCC_FMT_ATTR(3, 4)
137 sftp_error_setg(Error **errp, BDRVSSHState *s, const char *fs, ...)
139 va_list args;
140 char *msg;
142 va_start(args, fs);
143 msg = g_strdup_vprintf(fs, args);
144 va_end(args);
146 if (s->sftp) {
147 char *ssh_err;
148 int ssh_err_code;
149 unsigned long sftp_err_code;
151 /* This is not an errno. See <libssh2.h>. */
152 ssh_err_code = libssh2_session_last_error(s->session,
153 &ssh_err, NULL, 0);
154 /* See <libssh2_sftp.h>. */
155 sftp_err_code = libssh2_sftp_last_error((s)->sftp);
157 error_setg(errp,
158 "%s: %s (libssh2 error code: %d, sftp error code: %lu)",
159 msg, ssh_err, ssh_err_code, sftp_err_code);
160 } else {
161 error_setg(errp, "%s", msg);
163 g_free(msg);
166 static void GCC_FMT_ATTR(2, 3)
167 sftp_error_report(BDRVSSHState *s, const char *fs, ...)
169 va_list args;
171 va_start(args, fs);
172 error_vprintf(fs, args);
174 if ((s)->sftp) {
175 char *ssh_err;
176 int ssh_err_code;
177 unsigned long sftp_err_code;
179 /* This is not an errno. See <libssh2.h>. */
180 ssh_err_code = libssh2_session_last_error(s->session,
181 &ssh_err, NULL, 0);
182 /* See <libssh2_sftp.h>. */
183 sftp_err_code = libssh2_sftp_last_error((s)->sftp);
185 error_printf(": %s (libssh2 error code: %d, sftp error code: %lu)",
186 ssh_err, ssh_err_code, sftp_err_code);
189 va_end(args);
190 error_printf("\n");
193 static int parse_uri(const char *filename, QDict *options, Error **errp)
195 URI *uri = NULL;
196 QueryParams *qp = NULL;
197 int i;
199 uri = uri_parse(filename);
200 if (!uri) {
201 return -EINVAL;
204 if (strcmp(uri->scheme, "ssh") != 0) {
205 error_setg(errp, "URI scheme must be 'ssh'");
206 goto err;
209 if (!uri->server || strcmp(uri->server, "") == 0) {
210 error_setg(errp, "missing hostname in URI");
211 goto err;
214 if (!uri->path || strcmp(uri->path, "") == 0) {
215 error_setg(errp, "missing remote path in URI");
216 goto err;
219 qp = query_params_parse(uri->query);
220 if (!qp) {
221 error_setg(errp, "could not parse query parameters");
222 goto err;
225 if(uri->user && strcmp(uri->user, "") != 0) {
226 qdict_put(options, "user", qstring_from_str(uri->user));
229 qdict_put(options, "host", qstring_from_str(uri->server));
231 if (uri->port) {
232 qdict_put(options, "port", qint_from_int(uri->port));
235 qdict_put(options, "path", qstring_from_str(uri->path));
237 /* Pick out any query parameters that we understand, and ignore
238 * the rest.
240 for (i = 0; i < qp->n; ++i) {
241 if (strcmp(qp->p[i].name, "host_key_check") == 0) {
242 qdict_put(options, "host_key_check",
243 qstring_from_str(qp->p[i].value));
247 query_params_free(qp);
248 uri_free(uri);
249 return 0;
251 err:
252 if (qp) {
253 query_params_free(qp);
255 if (uri) {
256 uri_free(uri);
258 return -EINVAL;
261 static void ssh_parse_filename(const char *filename, QDict *options,
262 Error **errp)
264 if (qdict_haskey(options, "user") ||
265 qdict_haskey(options, "host") ||
266 qdict_haskey(options, "port") ||
267 qdict_haskey(options, "path") ||
268 qdict_haskey(options, "host_key_check")) {
269 error_setg(errp, "user, host, port, path, host_key_check cannot be used at the same time as a file option");
270 return;
273 parse_uri(filename, options, errp);
276 static int check_host_key_knownhosts(BDRVSSHState *s,
277 const char *host, int port, Error **errp)
279 const char *home;
280 char *knh_file = NULL;
281 LIBSSH2_KNOWNHOSTS *knh = NULL;
282 struct libssh2_knownhost *found;
283 int ret, r;
284 const char *hostkey;
285 size_t len;
286 int type;
288 hostkey = libssh2_session_hostkey(s->session, &len, &type);
289 if (!hostkey) {
290 ret = -EINVAL;
291 session_error_setg(errp, s, "failed to read remote host key");
292 goto out;
295 knh = libssh2_knownhost_init(s->session);
296 if (!knh) {
297 ret = -EINVAL;
298 session_error_setg(errp, s,
299 "failed to initialize known hosts support");
300 goto out;
303 home = getenv("HOME");
304 if (home) {
305 knh_file = g_strdup_printf("%s/.ssh/known_hosts", home);
306 } else {
307 knh_file = g_strdup_printf("/root/.ssh/known_hosts");
310 /* Read all known hosts from OpenSSH-style known_hosts file. */
311 libssh2_knownhost_readfile(knh, knh_file, LIBSSH2_KNOWNHOST_FILE_OPENSSH);
313 r = libssh2_knownhost_checkp(knh, host, port, hostkey, len,
314 LIBSSH2_KNOWNHOST_TYPE_PLAIN|
315 LIBSSH2_KNOWNHOST_KEYENC_RAW,
316 &found);
317 switch (r) {
318 case LIBSSH2_KNOWNHOST_CHECK_MATCH:
319 /* OK */
320 DPRINTF("host key OK: %s", found->key);
321 break;
322 case LIBSSH2_KNOWNHOST_CHECK_MISMATCH:
323 ret = -EINVAL;
324 session_error_setg(errp, s,
325 "host key does not match the one in known_hosts"
326 " (found key %s)", found->key);
327 goto out;
328 case LIBSSH2_KNOWNHOST_CHECK_NOTFOUND:
329 ret = -EINVAL;
330 session_error_setg(errp, s, "no host key was found in known_hosts");
331 goto out;
332 case LIBSSH2_KNOWNHOST_CHECK_FAILURE:
333 ret = -EINVAL;
334 session_error_setg(errp, s,
335 "failure matching the host key with known_hosts");
336 goto out;
337 default:
338 ret = -EINVAL;
339 session_error_setg(errp, s, "unknown error matching the host key"
340 " with known_hosts (%d)", r);
341 goto out;
344 /* known_hosts checking successful. */
345 ret = 0;
347 out:
348 if (knh != NULL) {
349 libssh2_knownhost_free(knh);
351 g_free(knh_file);
352 return ret;
355 static unsigned hex2decimal(char ch)
357 if (ch >= '0' && ch <= '9') {
358 return (ch - '0');
359 } else if (ch >= 'a' && ch <= 'f') {
360 return 10 + (ch - 'a');
361 } else if (ch >= 'A' && ch <= 'F') {
362 return 10 + (ch - 'A');
365 return -1;
368 /* Compare the binary fingerprint (hash of host key) with the
369 * host_key_check parameter.
371 static int compare_fingerprint(const unsigned char *fingerprint, size_t len,
372 const char *host_key_check)
374 unsigned c;
376 while (len > 0) {
377 while (*host_key_check == ':')
378 host_key_check++;
379 if (!qemu_isxdigit(host_key_check[0]) ||
380 !qemu_isxdigit(host_key_check[1]))
381 return 1;
382 c = hex2decimal(host_key_check[0]) * 16 +
383 hex2decimal(host_key_check[1]);
384 if (c - *fingerprint != 0)
385 return c - *fingerprint;
386 fingerprint++;
387 len--;
388 host_key_check += 2;
390 return *host_key_check - '\0';
393 static int
394 check_host_key_hash(BDRVSSHState *s, const char *hash,
395 int hash_type, size_t fingerprint_len, Error **errp)
397 const char *fingerprint;
399 fingerprint = libssh2_hostkey_hash(s->session, hash_type);
400 if (!fingerprint) {
401 session_error_setg(errp, s, "failed to read remote host key");
402 return -EINVAL;
405 if(compare_fingerprint((unsigned char *) fingerprint, fingerprint_len,
406 hash) != 0) {
407 error_setg(errp, "remote host key does not match host_key_check '%s'",
408 hash);
409 return -EPERM;
412 return 0;
415 static int check_host_key(BDRVSSHState *s, const char *host, int port,
416 const char *host_key_check, Error **errp)
418 /* host_key_check=no */
419 if (strcmp(host_key_check, "no") == 0) {
420 return 0;
423 /* host_key_check=md5:xx:yy:zz:... */
424 if (strncmp(host_key_check, "md5:", 4) == 0) {
425 return check_host_key_hash(s, &host_key_check[4],
426 LIBSSH2_HOSTKEY_HASH_MD5, 16, errp);
429 /* host_key_check=sha1:xx:yy:zz:... */
430 if (strncmp(host_key_check, "sha1:", 5) == 0) {
431 return check_host_key_hash(s, &host_key_check[5],
432 LIBSSH2_HOSTKEY_HASH_SHA1, 20, errp);
435 /* host_key_check=yes */
436 if (strcmp(host_key_check, "yes") == 0) {
437 return check_host_key_knownhosts(s, host, port, errp);
440 error_setg(errp, "unknown host_key_check setting (%s)", host_key_check);
441 return -EINVAL;
444 static int authenticate(BDRVSSHState *s, const char *user, Error **errp)
446 int r, ret;
447 const char *userauthlist;
448 LIBSSH2_AGENT *agent = NULL;
449 struct libssh2_agent_publickey *identity;
450 struct libssh2_agent_publickey *prev_identity = NULL;
452 userauthlist = libssh2_userauth_list(s->session, user, strlen(user));
453 if (strstr(userauthlist, "publickey") == NULL) {
454 ret = -EPERM;
455 error_setg(errp,
456 "remote server does not support \"publickey\" authentication");
457 goto out;
460 /* Connect to ssh-agent and try each identity in turn. */
461 agent = libssh2_agent_init(s->session);
462 if (!agent) {
463 ret = -EINVAL;
464 session_error_setg(errp, s, "failed to initialize ssh-agent support");
465 goto out;
467 if (libssh2_agent_connect(agent)) {
468 ret = -ECONNREFUSED;
469 session_error_setg(errp, s, "failed to connect to ssh-agent");
470 goto out;
472 if (libssh2_agent_list_identities(agent)) {
473 ret = -EINVAL;
474 session_error_setg(errp, s,
475 "failed requesting identities from ssh-agent");
476 goto out;
479 for(;;) {
480 r = libssh2_agent_get_identity(agent, &identity, prev_identity);
481 if (r == 1) { /* end of list */
482 break;
484 if (r < 0) {
485 ret = -EINVAL;
486 session_error_setg(errp, s,
487 "failed to obtain identity from ssh-agent");
488 goto out;
490 r = libssh2_agent_userauth(agent, user, identity);
491 if (r == 0) {
492 /* Authenticated! */
493 ret = 0;
494 goto out;
496 /* Failed to authenticate with this identity, try the next one. */
497 prev_identity = identity;
500 ret = -EPERM;
501 error_setg(errp, "failed to authenticate using publickey authentication "
502 "and the identities held by your ssh-agent");
504 out:
505 if (agent != NULL) {
506 /* Note: libssh2 implementation implicitly calls
507 * libssh2_agent_disconnect if necessary.
509 libssh2_agent_free(agent);
512 return ret;
515 static int connect_to_ssh(BDRVSSHState *s, QDict *options,
516 int ssh_flags, int creat_mode, Error **errp)
518 int r, ret;
519 const char *host, *user, *path, *host_key_check;
520 int port;
522 if (!qdict_haskey(options, "host")) {
523 ret = -EINVAL;
524 error_setg(errp, "No hostname was specified");
525 goto err;
527 host = qdict_get_str(options, "host");
529 if (qdict_haskey(options, "port")) {
530 port = qdict_get_int(options, "port");
531 } else {
532 port = 22;
535 if (!qdict_haskey(options, "path")) {
536 ret = -EINVAL;
537 error_setg(errp, "No path was specified");
538 goto err;
540 path = qdict_get_str(options, "path");
542 if (qdict_haskey(options, "user")) {
543 user = qdict_get_str(options, "user");
544 } else {
545 user = g_get_user_name();
546 if (!user) {
547 error_setg_errno(errp, errno, "Can't get user name");
548 ret = -errno;
549 goto err;
553 if (qdict_haskey(options, "host_key_check")) {
554 host_key_check = qdict_get_str(options, "host_key_check");
555 } else {
556 host_key_check = "yes";
559 /* Construct the host:port name for inet_connect. */
560 g_free(s->hostport);
561 s->hostport = g_strdup_printf("%s:%d", host, port);
563 /* Open the socket and connect. */
564 s->sock = inet_connect(s->hostport, errp);
565 if (s->sock < 0) {
566 ret = -EIO;
567 goto err;
570 /* Create SSH session. */
571 s->session = libssh2_session_init();
572 if (!s->session) {
573 ret = -EINVAL;
574 session_error_setg(errp, s, "failed to initialize libssh2 session");
575 goto err;
578 #if TRACE_LIBSSH2 != 0
579 libssh2_trace(s->session, TRACE_LIBSSH2);
580 #endif
582 r = libssh2_session_handshake(s->session, s->sock);
583 if (r != 0) {
584 ret = -EINVAL;
585 session_error_setg(errp, s, "failed to establish SSH session");
586 goto err;
589 /* Check the remote host's key against known_hosts. */
590 ret = check_host_key(s, host, port, host_key_check, errp);
591 if (ret < 0) {
592 goto err;
595 /* Authenticate. */
596 ret = authenticate(s, user, errp);
597 if (ret < 0) {
598 goto err;
601 /* Start SFTP. */
602 s->sftp = libssh2_sftp_init(s->session);
603 if (!s->sftp) {
604 session_error_setg(errp, s, "failed to initialize sftp handle");
605 ret = -EINVAL;
606 goto err;
609 /* Open the remote file. */
610 DPRINTF("opening file %s flags=0x%x creat_mode=0%o",
611 path, ssh_flags, creat_mode);
612 s->sftp_handle = libssh2_sftp_open(s->sftp, path, ssh_flags, creat_mode);
613 if (!s->sftp_handle) {
614 session_error_setg(errp, s, "failed to open remote file '%s'", path);
615 ret = -EINVAL;
616 goto err;
619 r = libssh2_sftp_fstat(s->sftp_handle, &s->attrs);
620 if (r < 0) {
621 sftp_error_setg(errp, s, "failed to read file attributes");
622 return -EINVAL;
625 /* Delete the options we've used; any not deleted will cause the
626 * block layer to give an error about unused options.
628 qdict_del(options, "host");
629 qdict_del(options, "port");
630 qdict_del(options, "user");
631 qdict_del(options, "path");
632 qdict_del(options, "host_key_check");
634 return 0;
636 err:
637 if (s->sftp_handle) {
638 libssh2_sftp_close(s->sftp_handle);
640 s->sftp_handle = NULL;
641 if (s->sftp) {
642 libssh2_sftp_shutdown(s->sftp);
644 s->sftp = NULL;
645 if (s->session) {
646 libssh2_session_disconnect(s->session,
647 "from qemu ssh client: "
648 "error opening connection");
649 libssh2_session_free(s->session);
651 s->session = NULL;
653 return ret;
656 static int ssh_file_open(BlockDriverState *bs, QDict *options, int bdrv_flags,
657 Error **errp)
659 BDRVSSHState *s = bs->opaque;
660 int ret;
661 int ssh_flags;
663 ssh_state_init(s);
665 ssh_flags = LIBSSH2_FXF_READ;
666 if (bdrv_flags & BDRV_O_RDWR) {
667 ssh_flags |= LIBSSH2_FXF_WRITE;
670 /* Start up SSH. */
671 ret = connect_to_ssh(s, options, ssh_flags, 0, errp);
672 if (ret < 0) {
673 goto err;
676 /* Go non-blocking. */
677 libssh2_session_set_blocking(s->session, 0);
679 return 0;
681 err:
682 if (s->sock >= 0) {
683 close(s->sock);
685 s->sock = -1;
687 return ret;
690 static QemuOptsList ssh_create_opts = {
691 .name = "ssh-create-opts",
692 .head = QTAILQ_HEAD_INITIALIZER(ssh_create_opts.head),
693 .desc = {
695 .name = BLOCK_OPT_SIZE,
696 .type = QEMU_OPT_SIZE,
697 .help = "Virtual disk size"
699 { /* end of list */ }
703 static int ssh_create(const char *filename, QemuOpts *opts, Error **errp)
705 int r, ret;
706 int64_t total_size = 0;
707 QDict *uri_options = NULL;
708 BDRVSSHState s;
709 ssize_t r2;
710 char c[1] = { '\0' };
712 ssh_state_init(&s);
714 /* Get desired file size. */
715 total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
716 BDRV_SECTOR_SIZE);
717 DPRINTF("total_size=%" PRIi64, total_size);
719 uri_options = qdict_new();
720 r = parse_uri(filename, uri_options, errp);
721 if (r < 0) {
722 ret = r;
723 goto out;
726 r = connect_to_ssh(&s, uri_options,
727 LIBSSH2_FXF_READ|LIBSSH2_FXF_WRITE|
728 LIBSSH2_FXF_CREAT|LIBSSH2_FXF_TRUNC,
729 0644, errp);
730 if (r < 0) {
731 ret = r;
732 goto out;
735 if (total_size > 0) {
736 libssh2_sftp_seek64(s.sftp_handle, total_size-1);
737 r2 = libssh2_sftp_write(s.sftp_handle, c, 1);
738 if (r2 < 0) {
739 sftp_error_setg(errp, &s, "truncate failed");
740 ret = -EINVAL;
741 goto out;
743 s.attrs.filesize = total_size;
746 ret = 0;
748 out:
749 ssh_state_free(&s);
750 if (uri_options != NULL) {
751 QDECREF(uri_options);
753 return ret;
756 static void ssh_close(BlockDriverState *bs)
758 BDRVSSHState *s = bs->opaque;
760 ssh_state_free(s);
763 static int ssh_has_zero_init(BlockDriverState *bs)
765 BDRVSSHState *s = bs->opaque;
766 /* Assume false, unless we can positively prove it's true. */
767 int has_zero_init = 0;
769 if (s->attrs.flags & LIBSSH2_SFTP_ATTR_PERMISSIONS) {
770 if (s->attrs.permissions & LIBSSH2_SFTP_S_IFREG) {
771 has_zero_init = 1;
775 return has_zero_init;
778 static void restart_coroutine(void *opaque)
780 Coroutine *co = opaque;
782 DPRINTF("co=%p", co);
784 qemu_coroutine_enter(co, NULL);
787 static coroutine_fn void set_fd_handler(BDRVSSHState *s, BlockDriverState *bs)
789 int r;
790 IOHandler *rd_handler = NULL, *wr_handler = NULL;
791 Coroutine *co = qemu_coroutine_self();
793 r = libssh2_session_block_directions(s->session);
795 if (r & LIBSSH2_SESSION_BLOCK_INBOUND) {
796 rd_handler = restart_coroutine;
798 if (r & LIBSSH2_SESSION_BLOCK_OUTBOUND) {
799 wr_handler = restart_coroutine;
802 DPRINTF("s->sock=%d rd_handler=%p wr_handler=%p", s->sock,
803 rd_handler, wr_handler);
805 aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock,
806 rd_handler, wr_handler, co);
809 static coroutine_fn void clear_fd_handler(BDRVSSHState *s,
810 BlockDriverState *bs)
812 DPRINTF("s->sock=%d", s->sock);
813 aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock, NULL, NULL, NULL);
816 /* A non-blocking call returned EAGAIN, so yield, ensuring the
817 * handlers are set up so that we'll be rescheduled when there is an
818 * interesting event on the socket.
820 static coroutine_fn void co_yield(BDRVSSHState *s, BlockDriverState *bs)
822 set_fd_handler(s, bs);
823 qemu_coroutine_yield();
824 clear_fd_handler(s, bs);
827 /* SFTP has a function `libssh2_sftp_seek64' which seeks to a position
828 * in the remote file. Notice that it just updates a field in the
829 * sftp_handle structure, so there is no network traffic and it cannot
830 * fail.
832 * However, `libssh2_sftp_seek64' does have a catastrophic effect on
833 * performance since it causes the handle to throw away all in-flight
834 * reads and buffered readahead data. Therefore this function tries
835 * to be intelligent about when to call the underlying libssh2 function.
837 #define SSH_SEEK_WRITE 0
838 #define SSH_SEEK_READ 1
839 #define SSH_SEEK_FORCE 2
841 static void ssh_seek(BDRVSSHState *s, int64_t offset, int flags)
843 bool op_read = (flags & SSH_SEEK_READ) != 0;
844 bool force = (flags & SSH_SEEK_FORCE) != 0;
846 if (force || op_read != s->offset_op_read || offset != s->offset) {
847 DPRINTF("seeking to offset=%" PRIi64, offset);
848 libssh2_sftp_seek64(s->sftp_handle, offset);
849 s->offset = offset;
850 s->offset_op_read = op_read;
854 static coroutine_fn int ssh_read(BDRVSSHState *s, BlockDriverState *bs,
855 int64_t offset, size_t size,
856 QEMUIOVector *qiov)
858 ssize_t r;
859 size_t got;
860 char *buf, *end_of_vec;
861 struct iovec *i;
863 DPRINTF("offset=%" PRIi64 " size=%zu", offset, size);
865 ssh_seek(s, offset, SSH_SEEK_READ);
867 /* This keeps track of the current iovec element ('i'), where we
868 * will write to next ('buf'), and the end of the current iovec
869 * ('end_of_vec').
871 i = &qiov->iov[0];
872 buf = i->iov_base;
873 end_of_vec = i->iov_base + i->iov_len;
875 /* libssh2 has a hard-coded limit of 2000 bytes per request,
876 * although it will also do readahead behind our backs. Therefore
877 * we may have to do repeated reads here until we have read 'size'
878 * bytes.
880 for (got = 0; got < size; ) {
881 again:
882 DPRINTF("sftp_read buf=%p size=%zu", buf, end_of_vec - buf);
883 r = libssh2_sftp_read(s->sftp_handle, buf, end_of_vec - buf);
884 DPRINTF("sftp_read returned %zd", r);
886 if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
887 co_yield(s, bs);
888 goto again;
890 if (r < 0) {
891 sftp_error_report(s, "read failed");
892 s->offset = -1;
893 return -EIO;
895 if (r == 0) {
896 /* EOF: Short read so pad the buffer with zeroes and return it. */
897 qemu_iovec_memset(qiov, got, 0, size - got);
898 return 0;
901 got += r;
902 buf += r;
903 s->offset += r;
904 if (buf >= end_of_vec && got < size) {
905 i++;
906 buf = i->iov_base;
907 end_of_vec = i->iov_base + i->iov_len;
911 return 0;
914 static coroutine_fn int ssh_co_readv(BlockDriverState *bs,
915 int64_t sector_num,
916 int nb_sectors, QEMUIOVector *qiov)
918 BDRVSSHState *s = bs->opaque;
919 int ret;
921 qemu_co_mutex_lock(&s->lock);
922 ret = ssh_read(s, bs, sector_num * BDRV_SECTOR_SIZE,
923 nb_sectors * BDRV_SECTOR_SIZE, qiov);
924 qemu_co_mutex_unlock(&s->lock);
926 return ret;
929 static int ssh_write(BDRVSSHState *s, BlockDriverState *bs,
930 int64_t offset, size_t size,
931 QEMUIOVector *qiov)
933 ssize_t r;
934 size_t written;
935 char *buf, *end_of_vec;
936 struct iovec *i;
938 DPRINTF("offset=%" PRIi64 " size=%zu", offset, size);
940 ssh_seek(s, offset, SSH_SEEK_WRITE);
942 /* This keeps track of the current iovec element ('i'), where we
943 * will read from next ('buf'), and the end of the current iovec
944 * ('end_of_vec').
946 i = &qiov->iov[0];
947 buf = i->iov_base;
948 end_of_vec = i->iov_base + i->iov_len;
950 for (written = 0; written < size; ) {
951 again:
952 DPRINTF("sftp_write buf=%p size=%zu", buf, end_of_vec - buf);
953 r = libssh2_sftp_write(s->sftp_handle, buf, end_of_vec - buf);
954 DPRINTF("sftp_write returned %zd", r);
956 if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
957 co_yield(s, bs);
958 goto again;
960 if (r < 0) {
961 sftp_error_report(s, "write failed");
962 s->offset = -1;
963 return -EIO;
965 /* The libssh2 API is very unclear about this. A comment in
966 * the code says "nothing was acked, and no EAGAIN was
967 * received!" which apparently means that no data got sent
968 * out, and the underlying channel didn't return any EAGAIN
969 * indication. I think this is a bug in either libssh2 or
970 * OpenSSH (server-side). In any case, forcing a seek (to
971 * discard libssh2 internal buffers), and then trying again
972 * works for me.
974 if (r == 0) {
975 ssh_seek(s, offset + written, SSH_SEEK_WRITE|SSH_SEEK_FORCE);
976 co_yield(s, bs);
977 goto again;
980 written += r;
981 buf += r;
982 s->offset += r;
983 if (buf >= end_of_vec && written < size) {
984 i++;
985 buf = i->iov_base;
986 end_of_vec = i->iov_base + i->iov_len;
989 if (offset + written > s->attrs.filesize)
990 s->attrs.filesize = offset + written;
993 return 0;
996 static coroutine_fn int ssh_co_writev(BlockDriverState *bs,
997 int64_t sector_num,
998 int nb_sectors, QEMUIOVector *qiov)
1000 BDRVSSHState *s = bs->opaque;
1001 int ret;
1003 qemu_co_mutex_lock(&s->lock);
1004 ret = ssh_write(s, bs, sector_num * BDRV_SECTOR_SIZE,
1005 nb_sectors * BDRV_SECTOR_SIZE, qiov);
1006 qemu_co_mutex_unlock(&s->lock);
1008 return ret;
1011 static void unsafe_flush_warning(BDRVSSHState *s, const char *what)
1013 if (!s->unsafe_flush_warning) {
1014 error_report("warning: ssh server %s does not support fsync",
1015 s->hostport);
1016 if (what) {
1017 error_report("to support fsync, you need %s", what);
1019 s->unsafe_flush_warning = true;
1023 #ifdef HAS_LIBSSH2_SFTP_FSYNC
1025 static coroutine_fn int ssh_flush(BDRVSSHState *s, BlockDriverState *bs)
1027 int r;
1029 DPRINTF("fsync");
1030 again:
1031 r = libssh2_sftp_fsync(s->sftp_handle);
1032 if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
1033 co_yield(s, bs);
1034 goto again;
1036 if (r == LIBSSH2_ERROR_SFTP_PROTOCOL &&
1037 libssh2_sftp_last_error(s->sftp) == LIBSSH2_FX_OP_UNSUPPORTED) {
1038 unsafe_flush_warning(s, "OpenSSH >= 6.3");
1039 return 0;
1041 if (r < 0) {
1042 sftp_error_report(s, "fsync failed");
1043 return -EIO;
1046 return 0;
1049 static coroutine_fn int ssh_co_flush(BlockDriverState *bs)
1051 BDRVSSHState *s = bs->opaque;
1052 int ret;
1054 qemu_co_mutex_lock(&s->lock);
1055 ret = ssh_flush(s, bs);
1056 qemu_co_mutex_unlock(&s->lock);
1058 return ret;
1061 #else /* !HAS_LIBSSH2_SFTP_FSYNC */
1063 static coroutine_fn int ssh_co_flush(BlockDriverState *bs)
1065 BDRVSSHState *s = bs->opaque;
1067 unsafe_flush_warning(s, "libssh2 >= 1.4.4");
1068 return 0;
1071 #endif /* !HAS_LIBSSH2_SFTP_FSYNC */
1073 static int64_t ssh_getlength(BlockDriverState *bs)
1075 BDRVSSHState *s = bs->opaque;
1076 int64_t length;
1078 /* Note we cannot make a libssh2 call here. */
1079 length = (int64_t) s->attrs.filesize;
1080 DPRINTF("length=%" PRIi64, length);
1082 return length;
1085 static BlockDriver bdrv_ssh = {
1086 .format_name = "ssh",
1087 .protocol_name = "ssh",
1088 .instance_size = sizeof(BDRVSSHState),
1089 .bdrv_parse_filename = ssh_parse_filename,
1090 .bdrv_file_open = ssh_file_open,
1091 .bdrv_create = ssh_create,
1092 .bdrv_close = ssh_close,
1093 .bdrv_has_zero_init = ssh_has_zero_init,
1094 .bdrv_co_readv = ssh_co_readv,
1095 .bdrv_co_writev = ssh_co_writev,
1096 .bdrv_getlength = ssh_getlength,
1097 .bdrv_co_flush_to_disk = ssh_co_flush,
1098 .create_opts = &ssh_create_opts,
1101 static void bdrv_ssh_init(void)
1103 int r;
1105 r = libssh2_init(0);
1106 if (r != 0) {
1107 fprintf(stderr, "libssh2 initialization failed, %d\n", r);
1108 exit(EXIT_FAILURE);
1111 bdrv_register(&bdrv_ssh);
1114 block_init(bdrv_ssh_init);