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0a12ec87
RJ
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
57typedef 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;
9a2d462e
RJ
75
76 /* Used to warn if 'flush' is not supported. */
77 char *hostport;
78 bool unsafe_flush_warning;
0a12ec87
RJ
79} BDRVSSHState;
80
81static void ssh_state_init(BDRVSSHState *s)
82{
83 memset(s, 0, sizeof *s);
84 s->sock = -1;
85 s->offset = -1;
86 qemu_co_mutex_init(&s->lock);
87}
88
89static void ssh_state_free(BDRVSSHState *s)
90{
9a2d462e 91 g_free(s->hostport);
0a12ec87
RJ
92 if (s->sftp_handle) {
93 libssh2_sftp_close(s->sftp_handle);
94 }
95 if (s->sftp) {
96 libssh2_sftp_shutdown(s->sftp);
97 }
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);
103 }
104 if (s->sock >= 0) {
105 close(s->sock);
106 }
107}
108
01c2b265
MA
109static void GCC_FMT_ATTR(3, 4)
110session_error_setg(Error **errp, BDRVSSHState *s, const char *fs, ...)
111{
112 va_list args;
113 char *msg;
114
115 va_start(args, fs);
116 msg = g_strdup_vprintf(fs, args);
117 va_end(args);
118
119 if (s->session) {
120 char *ssh_err;
121 int ssh_err_code;
122
123 /* This is not an errno. See <libssh2.h>. */
124 ssh_err_code = libssh2_session_last_error(s->session,
125 &ssh_err, NULL, 0);
126 error_setg(errp, "%s: %s (libssh2 error code: %d)",
127 msg, ssh_err, ssh_err_code);
128 } else {
129 error_setg(errp, "%s", msg);
130 }
131 g_free(msg);
132}
133
5496fb1a
MA
134static void GCC_FMT_ATTR(3, 4)
135sftp_error_setg(Error **errp, BDRVSSHState *s, const char *fs, ...)
0a12ec87
RJ
136{
137 va_list args;
5496fb1a 138 char *msg;
0a12ec87
RJ
139
140 va_start(args, fs);
5496fb1a
MA
141 msg = g_strdup_vprintf(fs, args);
142 va_end(args);
0a12ec87 143
5496fb1a 144 if (s->sftp) {
0a12ec87
RJ
145 char *ssh_err;
146 int ssh_err_code;
5496fb1a 147 unsigned long sftp_err_code;
0a12ec87 148
0a12ec87 149 /* This is not an errno. See <libssh2.h>. */
04bc7c0e
MA
150 ssh_err_code = libssh2_session_last_error(s->session,
151 &ssh_err, NULL, 0);
5496fb1a
MA
152 /* See <libssh2_sftp.h>. */
153 sftp_err_code = libssh2_sftp_last_error((s)->sftp);
0a12ec87 154
5496fb1a
MA
155 error_setg(errp,
156 "%s: %s (libssh2 error code: %d, sftp error code: %lu)",
157 msg, ssh_err, ssh_err_code, sftp_err_code);
158 } else {
159 error_setg(errp, "%s", msg);
160 }
161 g_free(msg);
0a12ec87
RJ
162}
163
6ae7d660 164static void GCC_FMT_ATTR(2, 3)
0a12ec87
RJ
165sftp_error_report(BDRVSSHState *s, const char *fs, ...)
166{
167 va_list args;
168
169 va_start(args, fs);
170 error_vprintf(fs, args);
171
172 if ((s)->sftp) {
173 char *ssh_err;
174 int ssh_err_code;
175 unsigned long sftp_err_code;
176
0a12ec87 177 /* This is not an errno. See <libssh2.h>. */
04bc7c0e
MA
178 ssh_err_code = libssh2_session_last_error(s->session,
179 &ssh_err, NULL, 0);
0a12ec87
RJ
180 /* See <libssh2_sftp.h>. */
181 sftp_err_code = libssh2_sftp_last_error((s)->sftp);
182
183 error_printf(": %s (libssh2 error code: %d, sftp error code: %lu)",
184 ssh_err, ssh_err_code, sftp_err_code);
185 }
186
187 va_end(args);
188 error_printf("\n");
189}
190
191static int parse_uri(const char *filename, QDict *options, Error **errp)
192{
193 URI *uri = NULL;
194 QueryParams *qp = NULL;
195 int i;
196
197 uri = uri_parse(filename);
198 if (!uri) {
199 return -EINVAL;
200 }
201
202 if (strcmp(uri->scheme, "ssh") != 0) {
203 error_setg(errp, "URI scheme must be 'ssh'");
204 goto err;
205 }
206
207 if (!uri->server || strcmp(uri->server, "") == 0) {
208 error_setg(errp, "missing hostname in URI");
209 goto err;
210 }
211
212 if (!uri->path || strcmp(uri->path, "") == 0) {
213 error_setg(errp, "missing remote path in URI");
214 goto err;
215 }
216
217 qp = query_params_parse(uri->query);
218 if (!qp) {
219 error_setg(errp, "could not parse query parameters");
220 goto err;
221 }
222
223 if(uri->user && strcmp(uri->user, "") != 0) {
224 qdict_put(options, "user", qstring_from_str(uri->user));
225 }
226
227 qdict_put(options, "host", qstring_from_str(uri->server));
228
229 if (uri->port) {
230 qdict_put(options, "port", qint_from_int(uri->port));
231 }
232
233 qdict_put(options, "path", qstring_from_str(uri->path));
234
235 /* Pick out any query parameters that we understand, and ignore
236 * the rest.
237 */
238 for (i = 0; i < qp->n; ++i) {
239 if (strcmp(qp->p[i].name, "host_key_check") == 0) {
240 qdict_put(options, "host_key_check",
241 qstring_from_str(qp->p[i].value));
242 }
243 }
244
245 query_params_free(qp);
246 uri_free(uri);
247 return 0;
248
249 err:
250 if (qp) {
251 query_params_free(qp);
252 }
253 if (uri) {
254 uri_free(uri);
255 }
256 return -EINVAL;
257}
258
259static void ssh_parse_filename(const char *filename, QDict *options,
260 Error **errp)
261{
262 if (qdict_haskey(options, "user") ||
263 qdict_haskey(options, "host") ||
264 qdict_haskey(options, "port") ||
265 qdict_haskey(options, "path") ||
266 qdict_haskey(options, "host_key_check")) {
267 error_setg(errp, "user, host, port, path, host_key_check cannot be used at the same time as a file option");
268 return;
269 }
270
271 parse_uri(filename, options, errp);
272}
273
274static int check_host_key_knownhosts(BDRVSSHState *s,
01c2b265 275 const char *host, int port, Error **errp)
0a12ec87
RJ
276{
277 const char *home;
278 char *knh_file = NULL;
279 LIBSSH2_KNOWNHOSTS *knh = NULL;
280 struct libssh2_knownhost *found;
281 int ret, r;
282 const char *hostkey;
283 size_t len;
284 int type;
285
286 hostkey = libssh2_session_hostkey(s->session, &len, &type);
287 if (!hostkey) {
288 ret = -EINVAL;
01c2b265 289 session_error_setg(errp, s, "failed to read remote host key");
0a12ec87
RJ
290 goto out;
291 }
292
293 knh = libssh2_knownhost_init(s->session);
294 if (!knh) {
295 ret = -EINVAL;
01c2b265
MA
296 session_error_setg(errp, s,
297 "failed to initialize known hosts support");
0a12ec87
RJ
298 goto out;
299 }
300
301 home = getenv("HOME");
302 if (home) {
303 knh_file = g_strdup_printf("%s/.ssh/known_hosts", home);
304 } else {
305 knh_file = g_strdup_printf("/root/.ssh/known_hosts");
306 }
307
308 /* Read all known hosts from OpenSSH-style known_hosts file. */
309 libssh2_knownhost_readfile(knh, knh_file, LIBSSH2_KNOWNHOST_FILE_OPENSSH);
310
311 r = libssh2_knownhost_checkp(knh, host, port, hostkey, len,
312 LIBSSH2_KNOWNHOST_TYPE_PLAIN|
313 LIBSSH2_KNOWNHOST_KEYENC_RAW,
314 &found);
315 switch (r) {
316 case LIBSSH2_KNOWNHOST_CHECK_MATCH:
317 /* OK */
318 DPRINTF("host key OK: %s", found->key);
319 break;
320 case LIBSSH2_KNOWNHOST_CHECK_MISMATCH:
321 ret = -EINVAL;
01c2b265
MA
322 session_error_setg(errp, s,
323 "host key does not match the one in known_hosts"
324 " (found key %s)", found->key);
0a12ec87
RJ
325 goto out;
326 case LIBSSH2_KNOWNHOST_CHECK_NOTFOUND:
327 ret = -EINVAL;
01c2b265 328 session_error_setg(errp, s, "no host key was found in known_hosts");
0a12ec87
RJ
329 goto out;
330 case LIBSSH2_KNOWNHOST_CHECK_FAILURE:
331 ret = -EINVAL;
01c2b265
MA
332 session_error_setg(errp, s,
333 "failure matching the host key with known_hosts");
0a12ec87
RJ
334 goto out;
335 default:
336 ret = -EINVAL;
01c2b265
MA
337 session_error_setg(errp, s, "unknown error matching the host key"
338 " with known_hosts (%d)", r);
0a12ec87
RJ
339 goto out;
340 }
341
342 /* known_hosts checking successful. */
343 ret = 0;
344
345 out:
346 if (knh != NULL) {
347 libssh2_knownhost_free(knh);
348 }
349 g_free(knh_file);
350 return ret;
351}
352
353static unsigned hex2decimal(char ch)
354{
355 if (ch >= '0' && ch <= '9') {
356 return (ch - '0');
357 } else if (ch >= 'a' && ch <= 'f') {
358 return 10 + (ch - 'a');
359 } else if (ch >= 'A' && ch <= 'F') {
360 return 10 + (ch - 'A');
361 }
362
363 return -1;
364}
365
366/* Compare the binary fingerprint (hash of host key) with the
367 * host_key_check parameter.
368 */
369static int compare_fingerprint(const unsigned char *fingerprint, size_t len,
370 const char *host_key_check)
371{
372 unsigned c;
373
374 while (len > 0) {
375 while (*host_key_check == ':')
376 host_key_check++;
377 if (!qemu_isxdigit(host_key_check[0]) ||
378 !qemu_isxdigit(host_key_check[1]))
379 return 1;
380 c = hex2decimal(host_key_check[0]) * 16 +
381 hex2decimal(host_key_check[1]);
382 if (c - *fingerprint != 0)
383 return c - *fingerprint;
384 fingerprint++;
385 len--;
386 host_key_check += 2;
387 }
388 return *host_key_check - '\0';
389}
390
391static int
392check_host_key_hash(BDRVSSHState *s, const char *hash,
01c2b265 393 int hash_type, size_t fingerprint_len, Error **errp)
0a12ec87
RJ
394{
395 const char *fingerprint;
396
397 fingerprint = libssh2_hostkey_hash(s->session, hash_type);
398 if (!fingerprint) {
01c2b265 399 session_error_setg(errp, s, "failed to read remote host key");
0a12ec87
RJ
400 return -EINVAL;
401 }
402
403 if(compare_fingerprint((unsigned char *) fingerprint, fingerprint_len,
404 hash) != 0) {
01c2b265
MA
405 error_setg(errp, "remote host key does not match host_key_check '%s'",
406 hash);
0a12ec87
RJ
407 return -EPERM;
408 }
409
410 return 0;
411}
412
413static int check_host_key(BDRVSSHState *s, const char *host, int port,
01c2b265 414 const char *host_key_check, Error **errp)
0a12ec87
RJ
415{
416 /* host_key_check=no */
417 if (strcmp(host_key_check, "no") == 0) {
418 return 0;
419 }
420
421 /* host_key_check=md5:xx:yy:zz:... */
c7a101f5 422 if (strncmp(host_key_check, "md5:", 4) == 0) {
0a12ec87 423 return check_host_key_hash(s, &host_key_check[4],
01c2b265 424 LIBSSH2_HOSTKEY_HASH_MD5, 16, errp);
0a12ec87
RJ
425 }
426
427 /* host_key_check=sha1:xx:yy:zz:... */
c7a101f5 428 if (strncmp(host_key_check, "sha1:", 5) == 0) {
0a12ec87 429 return check_host_key_hash(s, &host_key_check[5],
01c2b265 430 LIBSSH2_HOSTKEY_HASH_SHA1, 20, errp);
0a12ec87
RJ
431 }
432
433 /* host_key_check=yes */
434 if (strcmp(host_key_check, "yes") == 0) {
01c2b265 435 return check_host_key_knownhosts(s, host, port, errp);
0a12ec87
RJ
436 }
437
01c2b265 438 error_setg(errp, "unknown host_key_check setting (%s)", host_key_check);
0a12ec87
RJ
439 return -EINVAL;
440}
441
4618e658 442static int authenticate(BDRVSSHState *s, const char *user, Error **errp)
0a12ec87
RJ
443{
444 int r, ret;
445 const char *userauthlist;
446 LIBSSH2_AGENT *agent = NULL;
447 struct libssh2_agent_publickey *identity;
448 struct libssh2_agent_publickey *prev_identity = NULL;
449
450 userauthlist = libssh2_userauth_list(s->session, user, strlen(user));
451 if (strstr(userauthlist, "publickey") == NULL) {
452 ret = -EPERM;
4618e658
MA
453 error_setg(errp,
454 "remote server does not support \"publickey\" authentication");
0a12ec87
RJ
455 goto out;
456 }
457
458 /* Connect to ssh-agent and try each identity in turn. */
459 agent = libssh2_agent_init(s->session);
460 if (!agent) {
461 ret = -EINVAL;
4618e658 462 session_error_setg(errp, s, "failed to initialize ssh-agent support");
0a12ec87
RJ
463 goto out;
464 }
465 if (libssh2_agent_connect(agent)) {
466 ret = -ECONNREFUSED;
4618e658 467 session_error_setg(errp, s, "failed to connect to ssh-agent");
0a12ec87
RJ
468 goto out;
469 }
470 if (libssh2_agent_list_identities(agent)) {
471 ret = -EINVAL;
4618e658
MA
472 session_error_setg(errp, s,
473 "failed requesting identities from ssh-agent");
0a12ec87
RJ
474 goto out;
475 }
476
477 for(;;) {
478 r = libssh2_agent_get_identity(agent, &identity, prev_identity);
479 if (r == 1) { /* end of list */
480 break;
481 }
482 if (r < 0) {
483 ret = -EINVAL;
4618e658
MA
484 session_error_setg(errp, s,
485 "failed to obtain identity from ssh-agent");
0a12ec87
RJ
486 goto out;
487 }
488 r = libssh2_agent_userauth(agent, user, identity);
489 if (r == 0) {
490 /* Authenticated! */
491 ret = 0;
492 goto out;
493 }
494 /* Failed to authenticate with this identity, try the next one. */
495 prev_identity = identity;
496 }
497
498 ret = -EPERM;
4618e658
MA
499 error_setg(errp, "failed to authenticate using publickey authentication "
500 "and the identities held by your ssh-agent");
0a12ec87
RJ
501
502 out:
503 if (agent != NULL) {
504 /* Note: libssh2 implementation implicitly calls
505 * libssh2_agent_disconnect if necessary.
506 */
507 libssh2_agent_free(agent);
508 }
509
510 return ret;
511}
512
513static int connect_to_ssh(BDRVSSHState *s, QDict *options,
5f0c39e5 514 int ssh_flags, int creat_mode, Error **errp)
0a12ec87
RJ
515{
516 int r, ret;
0a12ec87
RJ
517 const char *host, *user, *path, *host_key_check;
518 int port;
0a12ec87
RJ
519
520 host = qdict_get_str(options, "host");
521
522 if (qdict_haskey(options, "port")) {
523 port = qdict_get_int(options, "port");
524 } else {
525 port = 22;
526 }
527
528 path = qdict_get_str(options, "path");
529
530 if (qdict_haskey(options, "user")) {
531 user = qdict_get_str(options, "user");
532 } else {
533 user = g_get_user_name();
534 if (!user) {
5f0c39e5 535 error_setg_errno(errp, errno, "Can't get user name");
0a12ec87
RJ
536 ret = -errno;
537 goto err;
538 }
539 }
540
541 if (qdict_haskey(options, "host_key_check")) {
542 host_key_check = qdict_get_str(options, "host_key_check");
543 } else {
544 host_key_check = "yes";
545 }
546
9a2d462e
RJ
547 /* Construct the host:port name for inet_connect. */
548 g_free(s->hostport);
549 s->hostport = g_strdup_printf("%s:%d", host, port);
550
0a12ec87 551 /* Open the socket and connect. */
5f0c39e5
MA
552 s->sock = inet_connect(s->hostport, errp);
553 if (s->sock < 0) {
0a12ec87 554 ret = -errno;
0a12ec87
RJ
555 goto err;
556 }
557
558 /* Create SSH session. */
559 s->session = libssh2_session_init();
560 if (!s->session) {
561 ret = -EINVAL;
5f0c39e5 562 session_error_setg(errp, s, "failed to initialize libssh2 session");
0a12ec87
RJ
563 goto err;
564 }
565
566#if TRACE_LIBSSH2 != 0
567 libssh2_trace(s->session, TRACE_LIBSSH2);
568#endif
569
570 r = libssh2_session_handshake(s->session, s->sock);
571 if (r != 0) {
572 ret = -EINVAL;
5f0c39e5 573 session_error_setg(errp, s, "failed to establish SSH session");
0a12ec87
RJ
574 goto err;
575 }
576
577 /* Check the remote host's key against known_hosts. */
5f0c39e5 578 ret = check_host_key(s, host, port, host_key_check, errp);
0a12ec87
RJ
579 if (ret < 0) {
580 goto err;
581 }
582
583 /* Authenticate. */
5f0c39e5 584 ret = authenticate(s, user, errp);
0a12ec87
RJ
585 if (ret < 0) {
586 goto err;
587 }
588
589 /* Start SFTP. */
590 s->sftp = libssh2_sftp_init(s->session);
591 if (!s->sftp) {
5f0c39e5 592 session_error_setg(errp, s, "failed to initialize sftp handle");
0a12ec87
RJ
593 ret = -EINVAL;
594 goto err;
595 }
596
597 /* Open the remote file. */
598 DPRINTF("opening file %s flags=0x%x creat_mode=0%o",
599 path, ssh_flags, creat_mode);
600 s->sftp_handle = libssh2_sftp_open(s->sftp, path, ssh_flags, creat_mode);
601 if (!s->sftp_handle) {
5496fb1a 602 session_error_setg(errp, s, "failed to open remote file '%s'", path);
0a12ec87
RJ
603 ret = -EINVAL;
604 goto err;
605 }
606
607 r = libssh2_sftp_fstat(s->sftp_handle, &s->attrs);
608 if (r < 0) {
5496fb1a 609 sftp_error_setg(errp, s, "failed to read file attributes");
0a12ec87
RJ
610 return -EINVAL;
611 }
612
613 /* Delete the options we've used; any not deleted will cause the
614 * block layer to give an error about unused options.
615 */
616 qdict_del(options, "host");
617 qdict_del(options, "port");
618 qdict_del(options, "user");
619 qdict_del(options, "path");
620 qdict_del(options, "host_key_check");
621
0a12ec87
RJ
622 return 0;
623
624 err:
625 if (s->sftp_handle) {
626 libssh2_sftp_close(s->sftp_handle);
627 }
628 s->sftp_handle = NULL;
629 if (s->sftp) {
630 libssh2_sftp_shutdown(s->sftp);
631 }
632 s->sftp = NULL;
633 if (s->session) {
634 libssh2_session_disconnect(s->session,
635 "from qemu ssh client: "
636 "error opening connection");
637 libssh2_session_free(s->session);
638 }
639 s->session = NULL;
0a12ec87
RJ
640
641 return ret;
642}
643
015a1036
HR
644static int ssh_file_open(BlockDriverState *bs, QDict *options, int bdrv_flags,
645 Error **errp)
0a12ec87
RJ
646{
647 BDRVSSHState *s = bs->opaque;
648 int ret;
649 int ssh_flags;
650
651 ssh_state_init(s);
652
653 ssh_flags = LIBSSH2_FXF_READ;
654 if (bdrv_flags & BDRV_O_RDWR) {
655 ssh_flags |= LIBSSH2_FXF_WRITE;
656 }
657
658 /* Start up SSH. */
5496fb1a 659 ret = connect_to_ssh(s, options, ssh_flags, 0, errp);
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RJ
660 if (ret < 0) {
661 goto err;
662 }
663
664 /* Go non-blocking. */
665 libssh2_session_set_blocking(s->session, 0);
666
667 return 0;
668
669 err:
670 if (s->sock >= 0) {
671 close(s->sock);
672 }
673 s->sock = -1;
674
675 return ret;
676}
677
766181fe
CL
678static QemuOptsList ssh_create_opts = {
679 .name = "ssh-create-opts",
680 .head = QTAILQ_HEAD_INITIALIZER(ssh_create_opts.head),
681 .desc = {
682 {
683 .name = BLOCK_OPT_SIZE,
684 .type = QEMU_OPT_SIZE,
685 .help = "Virtual disk size"
686 },
687 { /* end of list */ }
688 }
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RJ
689};
690
766181fe 691static int ssh_create(const char *filename, QemuOpts *opts, Error **errp)
0a12ec87
RJ
692{
693 int r, ret;
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RJ
694 int64_t total_size = 0;
695 QDict *uri_options = NULL;
696 BDRVSSHState s;
697 ssize_t r2;
698 char c[1] = { '\0' };
699
700 ssh_state_init(&s);
701
702 /* Get desired file size. */
766181fe 703 total_size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
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RJ
704 DPRINTF("total_size=%" PRIi64, total_size);
705
706 uri_options = qdict_new();
5496fb1a 707 r = parse_uri(filename, uri_options, errp);
0a12ec87 708 if (r < 0) {
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RJ
709 ret = r;
710 goto out;
711 }
712
713 r = connect_to_ssh(&s, uri_options,
714 LIBSSH2_FXF_READ|LIBSSH2_FXF_WRITE|
5f0c39e5 715 LIBSSH2_FXF_CREAT|LIBSSH2_FXF_TRUNC,
5496fb1a 716 0644, errp);
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RJ
717 if (r < 0) {
718 ret = r;
719 goto out;
720 }
721
722 if (total_size > 0) {
723 libssh2_sftp_seek64(s.sftp_handle, total_size-1);
724 r2 = libssh2_sftp_write(s.sftp_handle, c, 1);
725 if (r2 < 0) {
5496fb1a 726 sftp_error_setg(errp, &s, "truncate failed");
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RJ
727 ret = -EINVAL;
728 goto out;
729 }
730 s.attrs.filesize = total_size;
731 }
732
733 ret = 0;
734
735 out:
736 ssh_state_free(&s);
737 if (uri_options != NULL) {
738 QDECREF(uri_options);
739 }
740 return ret;
741}
742
743static void ssh_close(BlockDriverState *bs)
744{
745 BDRVSSHState *s = bs->opaque;
746
747 ssh_state_free(s);
748}
749
0b3f21e6
RJ
750static int ssh_has_zero_init(BlockDriverState *bs)
751{
752 BDRVSSHState *s = bs->opaque;
753 /* Assume false, unless we can positively prove it's true. */
754 int has_zero_init = 0;
755
756 if (s->attrs.flags & LIBSSH2_SFTP_ATTR_PERMISSIONS) {
757 if (s->attrs.permissions & LIBSSH2_SFTP_S_IFREG) {
758 has_zero_init = 1;
759 }
760 }
761
762 return has_zero_init;
763}
764
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RJ
765static void restart_coroutine(void *opaque)
766{
767 Coroutine *co = opaque;
768
769 DPRINTF("co=%p", co);
770
771 qemu_coroutine_enter(co, NULL);
772}
773
2af0b200 774static coroutine_fn void set_fd_handler(BDRVSSHState *s, BlockDriverState *bs)
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RJ
775{
776 int r;
777 IOHandler *rd_handler = NULL, *wr_handler = NULL;
778 Coroutine *co = qemu_coroutine_self();
779
780 r = libssh2_session_block_directions(s->session);
781
782 if (r & LIBSSH2_SESSION_BLOCK_INBOUND) {
783 rd_handler = restart_coroutine;
784 }
785 if (r & LIBSSH2_SESSION_BLOCK_OUTBOUND) {
786 wr_handler = restart_coroutine;
787 }
788
789 DPRINTF("s->sock=%d rd_handler=%p wr_handler=%p", s->sock,
790 rd_handler, wr_handler);
791
2af0b200
SH
792 aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock,
793 rd_handler, wr_handler, co);
0a12ec87
RJ
794}
795
2af0b200
SH
796static coroutine_fn void clear_fd_handler(BDRVSSHState *s,
797 BlockDriverState *bs)
0a12ec87
RJ
798{
799 DPRINTF("s->sock=%d", s->sock);
2af0b200 800 aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock, NULL, NULL, NULL);
0a12ec87
RJ
801}
802
803/* A non-blocking call returned EAGAIN, so yield, ensuring the
804 * handlers are set up so that we'll be rescheduled when there is an
805 * interesting event on the socket.
806 */
2af0b200 807static coroutine_fn void co_yield(BDRVSSHState *s, BlockDriverState *bs)
0a12ec87 808{
2af0b200 809 set_fd_handler(s, bs);
0a12ec87 810 qemu_coroutine_yield();
2af0b200 811 clear_fd_handler(s, bs);
0a12ec87
RJ
812}
813
814/* SFTP has a function `libssh2_sftp_seek64' which seeks to a position
815 * in the remote file. Notice that it just updates a field in the
816 * sftp_handle structure, so there is no network traffic and it cannot
817 * fail.
818 *
819 * However, `libssh2_sftp_seek64' does have a catastrophic effect on
820 * performance since it causes the handle to throw away all in-flight
821 * reads and buffered readahead data. Therefore this function tries
822 * to be intelligent about when to call the underlying libssh2 function.
823 */
824#define SSH_SEEK_WRITE 0
825#define SSH_SEEK_READ 1
826#define SSH_SEEK_FORCE 2
827
828static void ssh_seek(BDRVSSHState *s, int64_t offset, int flags)
829{
830 bool op_read = (flags & SSH_SEEK_READ) != 0;
831 bool force = (flags & SSH_SEEK_FORCE) != 0;
832
833 if (force || op_read != s->offset_op_read || offset != s->offset) {
834 DPRINTF("seeking to offset=%" PRIi64, offset);
835 libssh2_sftp_seek64(s->sftp_handle, offset);
836 s->offset = offset;
837 s->offset_op_read = op_read;
838 }
839}
840
2af0b200 841static coroutine_fn int ssh_read(BDRVSSHState *s, BlockDriverState *bs,
0a12ec87
RJ
842 int64_t offset, size_t size,
843 QEMUIOVector *qiov)
844{
845 ssize_t r;
846 size_t got;
847 char *buf, *end_of_vec;
848 struct iovec *i;
849
850 DPRINTF("offset=%" PRIi64 " size=%zu", offset, size);
851
852 ssh_seek(s, offset, SSH_SEEK_READ);
853
854 /* This keeps track of the current iovec element ('i'), where we
855 * will write to next ('buf'), and the end of the current iovec
856 * ('end_of_vec').
857 */
858 i = &qiov->iov[0];
859 buf = i->iov_base;
860 end_of_vec = i->iov_base + i->iov_len;
861
862 /* libssh2 has a hard-coded limit of 2000 bytes per request,
863 * although it will also do readahead behind our backs. Therefore
864 * we may have to do repeated reads here until we have read 'size'
865 * bytes.
866 */
867 for (got = 0; got < size; ) {
868 again:
869 DPRINTF("sftp_read buf=%p size=%zu", buf, end_of_vec - buf);
870 r = libssh2_sftp_read(s->sftp_handle, buf, end_of_vec - buf);
871 DPRINTF("sftp_read returned %zd", r);
872
873 if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
2af0b200 874 co_yield(s, bs);
0a12ec87
RJ
875 goto again;
876 }
877 if (r < 0) {
878 sftp_error_report(s, "read failed");
879 s->offset = -1;
880 return -EIO;
881 }
882 if (r == 0) {
883 /* EOF: Short read so pad the buffer with zeroes and return it. */
884 qemu_iovec_memset(qiov, got, 0, size - got);
885 return 0;
886 }
887
888 got += r;
889 buf += r;
890 s->offset += r;
891 if (buf >= end_of_vec && got < size) {
892 i++;
893 buf = i->iov_base;
894 end_of_vec = i->iov_base + i->iov_len;
895 }
896 }
897
898 return 0;
899}
900
901static coroutine_fn int ssh_co_readv(BlockDriverState *bs,
902 int64_t sector_num,
903 int nb_sectors, QEMUIOVector *qiov)
904{
905 BDRVSSHState *s = bs->opaque;
906 int ret;
907
908 qemu_co_mutex_lock(&s->lock);
2af0b200 909 ret = ssh_read(s, bs, sector_num * BDRV_SECTOR_SIZE,
0a12ec87
RJ
910 nb_sectors * BDRV_SECTOR_SIZE, qiov);
911 qemu_co_mutex_unlock(&s->lock);
912
913 return ret;
914}
915
2af0b200 916static int ssh_write(BDRVSSHState *s, BlockDriverState *bs,
0a12ec87
RJ
917 int64_t offset, size_t size,
918 QEMUIOVector *qiov)
919{
920 ssize_t r;
921 size_t written;
922 char *buf, *end_of_vec;
923 struct iovec *i;
924
925 DPRINTF("offset=%" PRIi64 " size=%zu", offset, size);
926
927 ssh_seek(s, offset, SSH_SEEK_WRITE);
928
929 /* This keeps track of the current iovec element ('i'), where we
930 * will read from next ('buf'), and the end of the current iovec
931 * ('end_of_vec').
932 */
933 i = &qiov->iov[0];
934 buf = i->iov_base;
935 end_of_vec = i->iov_base + i->iov_len;
936
937 for (written = 0; written < size; ) {
938 again:
939 DPRINTF("sftp_write buf=%p size=%zu", buf, end_of_vec - buf);
940 r = libssh2_sftp_write(s->sftp_handle, buf, end_of_vec - buf);
941 DPRINTF("sftp_write returned %zd", r);
942
943 if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
2af0b200 944 co_yield(s, bs);
0a12ec87
RJ
945 goto again;
946 }
947 if (r < 0) {
948 sftp_error_report(s, "write failed");
949 s->offset = -1;
950 return -EIO;
951 }
952 /* The libssh2 API is very unclear about this. A comment in
953 * the code says "nothing was acked, and no EAGAIN was
954 * received!" which apparently means that no data got sent
955 * out, and the underlying channel didn't return any EAGAIN
956 * indication. I think this is a bug in either libssh2 or
957 * OpenSSH (server-side). In any case, forcing a seek (to
958 * discard libssh2 internal buffers), and then trying again
959 * works for me.
960 */
961 if (r == 0) {
962 ssh_seek(s, offset + written, SSH_SEEK_WRITE|SSH_SEEK_FORCE);
2af0b200 963 co_yield(s, bs);
0a12ec87
RJ
964 goto again;
965 }
966
967 written += r;
968 buf += r;
969 s->offset += r;
970 if (buf >= end_of_vec && written < size) {
971 i++;
972 buf = i->iov_base;
973 end_of_vec = i->iov_base + i->iov_len;
974 }
975
976 if (offset + written > s->attrs.filesize)
977 s->attrs.filesize = offset + written;
978 }
979
980 return 0;
981}
982
983static coroutine_fn int ssh_co_writev(BlockDriverState *bs,
984 int64_t sector_num,
985 int nb_sectors, QEMUIOVector *qiov)
986{
987 BDRVSSHState *s = bs->opaque;
988 int ret;
989
990 qemu_co_mutex_lock(&s->lock);
2af0b200 991 ret = ssh_write(s, bs, sector_num * BDRV_SECTOR_SIZE,
0a12ec87
RJ
992 nb_sectors * BDRV_SECTOR_SIZE, qiov);
993 qemu_co_mutex_unlock(&s->lock);
994
995 return ret;
996}
997
9a2d462e
RJ
998static void unsafe_flush_warning(BDRVSSHState *s, const char *what)
999{
1000 if (!s->unsafe_flush_warning) {
1001 error_report("warning: ssh server %s does not support fsync",
1002 s->hostport);
1003 if (what) {
1004 error_report("to support fsync, you need %s", what);
1005 }
1006 s->unsafe_flush_warning = true;
1007 }
1008}
1009
1010#ifdef HAS_LIBSSH2_SFTP_FSYNC
1011
2af0b200 1012static coroutine_fn int ssh_flush(BDRVSSHState *s, BlockDriverState *bs)
9a2d462e
RJ
1013{
1014 int r;
1015
1016 DPRINTF("fsync");
1017 again:
1018 r = libssh2_sftp_fsync(s->sftp_handle);
1019 if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
2af0b200 1020 co_yield(s, bs);
9a2d462e
RJ
1021 goto again;
1022 }
1023 if (r == LIBSSH2_ERROR_SFTP_PROTOCOL &&
1024 libssh2_sftp_last_error(s->sftp) == LIBSSH2_FX_OP_UNSUPPORTED) {
1025 unsafe_flush_warning(s, "OpenSSH >= 6.3");
1026 return 0;
1027 }
1028 if (r < 0) {
1029 sftp_error_report(s, "fsync failed");
1030 return -EIO;
1031 }
1032
1033 return 0;
1034}
1035
1036static coroutine_fn int ssh_co_flush(BlockDriverState *bs)
1037{
1038 BDRVSSHState *s = bs->opaque;
1039 int ret;
1040
1041 qemu_co_mutex_lock(&s->lock);
2af0b200 1042 ret = ssh_flush(s, bs);
9a2d462e
RJ
1043 qemu_co_mutex_unlock(&s->lock);
1044
1045 return ret;
1046}
1047
1048#else /* !HAS_LIBSSH2_SFTP_FSYNC */
1049
1050static coroutine_fn int ssh_co_flush(BlockDriverState *bs)
1051{
1052 BDRVSSHState *s = bs->opaque;
1053
1054 unsafe_flush_warning(s, "libssh2 >= 1.4.4");
1055 return 0;
1056}
1057
1058#endif /* !HAS_LIBSSH2_SFTP_FSYNC */
1059
0a12ec87
RJ
1060static int64_t ssh_getlength(BlockDriverState *bs)
1061{
1062 BDRVSSHState *s = bs->opaque;
1063 int64_t length;
1064
1065 /* Note we cannot make a libssh2 call here. */
1066 length = (int64_t) s->attrs.filesize;
1067 DPRINTF("length=%" PRIi64, length);
1068
1069 return length;
1070}
1071
1072static BlockDriver bdrv_ssh = {
1073 .format_name = "ssh",
1074 .protocol_name = "ssh",
1075 .instance_size = sizeof(BDRVSSHState),
1076 .bdrv_parse_filename = ssh_parse_filename,
1077 .bdrv_file_open = ssh_file_open,
c282e1fd 1078 .bdrv_create = ssh_create,
0a12ec87 1079 .bdrv_close = ssh_close,
0b3f21e6 1080 .bdrv_has_zero_init = ssh_has_zero_init,
0a12ec87
RJ
1081 .bdrv_co_readv = ssh_co_readv,
1082 .bdrv_co_writev = ssh_co_writev,
1083 .bdrv_getlength = ssh_getlength,
9a2d462e 1084 .bdrv_co_flush_to_disk = ssh_co_flush,
766181fe 1085 .create_opts = &ssh_create_opts,
0a12ec87
RJ
1086};
1087
1088static void bdrv_ssh_init(void)
1089{
1090 int r;
1091
1092 r = libssh2_init(0);
1093 if (r != 0) {
1094 fprintf(stderr, "libssh2 initialization failed, %d\n", r);
1095 exit(EXIT_FAILURE);
1096 }
1097
1098 bdrv_register(&bdrv_ssh);
1099}
1100
1101block_init(bdrv_ssh_init);