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[mirror_qemu.git] / nbd / client.c
1 /*
2 * Copyright (C) 2016-2017 Red Hat, Inc.
3 * Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws>
4 *
5 * Network Block Device Client Side
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; under version 2 of the License.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, see <http://www.gnu.org/licenses/>.
18 */
19
20 #include "qemu/osdep.h"
21 #include "qapi/error.h"
22 #include "trace.h"
23 #include "nbd-internal.h"
24
25 /* Definitions for opaque data types */
26
27 static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
28
29 /* That's all folks */
30
31 /* Basic flow for negotiation
32
33 Server Client
34 Negotiate
35
36 or
37
38 Server Client
39 Negotiate #1
40 Option
41 Negotiate #2
42
43 ----
44
45 followed by
46
47 Server Client
48 Request
49 Response
50 Request
51 Response
52 ...
53 ...
54 Request (type == 2)
55
56 */
57
58 /* Send an option request.
59 *
60 * The request is for option @opt, with @data containing @len bytes of
61 * additional payload for the request (@len may be -1 to treat @data as
62 * a C string; and @data may be NULL if @len is 0).
63 * Return 0 if successful, -1 with errp set if it is impossible to
64 * continue. */
65 static int nbd_send_option_request(QIOChannel *ioc, uint32_t opt,
66 uint32_t len, const char *data,
67 Error **errp)
68 {
69 NBDOption req;
70 QEMU_BUILD_BUG_ON(sizeof(req) != 16);
71
72 if (len == -1) {
73 req.length = len = strlen(data);
74 }
75 trace_nbd_send_option_request(opt, nbd_opt_lookup(opt), len);
76
77 stq_be_p(&req.magic, NBD_OPTS_MAGIC);
78 stl_be_p(&req.option, opt);
79 stl_be_p(&req.length, len);
80
81 if (nbd_write(ioc, &req, sizeof(req), errp) < 0) {
82 error_prepend(errp, "Failed to send option request header: ");
83 return -1;
84 }
85
86 if (len && nbd_write(ioc, (char *) data, len, errp) < 0) {
87 error_prepend(errp, "Failed to send option request data: ");
88 return -1;
89 }
90
91 return 0;
92 }
93
94 /* Send NBD_OPT_ABORT as a courtesy to let the server know that we are
95 * not going to attempt further negotiation. */
96 static void nbd_send_opt_abort(QIOChannel *ioc)
97 {
98 /* Technically, a compliant server is supposed to reply to us; but
99 * older servers disconnected instead. At any rate, we're allowed
100 * to disconnect without waiting for the server reply, so we don't
101 * even care if the request makes it to the server, let alone
102 * waiting around for whether the server replies. */
103 nbd_send_option_request(ioc, NBD_OPT_ABORT, 0, NULL, NULL);
104 }
105
106
107 /* Receive the header of an option reply, which should match the given
108 * opt. Read through the length field, but NOT the length bytes of
109 * payload. Return 0 if successful, -1 with errp set if it is
110 * impossible to continue. */
111 static int nbd_receive_option_reply(QIOChannel *ioc, uint32_t opt,
112 NBDOptionReply *reply, Error **errp)
113 {
114 QEMU_BUILD_BUG_ON(sizeof(*reply) != 20);
115 if (nbd_read(ioc, reply, sizeof(*reply), errp) < 0) {
116 error_prepend(errp, "failed to read option reply: ");
117 nbd_send_opt_abort(ioc);
118 return -1;
119 }
120 be64_to_cpus(&reply->magic);
121 be32_to_cpus(&reply->option);
122 be32_to_cpus(&reply->type);
123 be32_to_cpus(&reply->length);
124
125 trace_nbd_receive_option_reply(reply->option, nbd_opt_lookup(reply->option),
126 reply->type, nbd_rep_lookup(reply->type),
127 reply->length);
128
129 if (reply->magic != NBD_REP_MAGIC) {
130 error_setg(errp, "Unexpected option reply magic");
131 nbd_send_opt_abort(ioc);
132 return -1;
133 }
134 if (reply->option != opt) {
135 error_setg(errp, "Unexpected option type %x expected %x",
136 reply->option, opt);
137 nbd_send_opt_abort(ioc);
138 return -1;
139 }
140 return 0;
141 }
142
143 /* If reply represents success, return 1 without further action.
144 * If reply represents an error, consume the optional payload of
145 * the packet on ioc. Then return 0 for unsupported (so the client
146 * can fall back to other approaches), or -1 with errp set for other
147 * errors.
148 */
149 static int nbd_handle_reply_err(QIOChannel *ioc, NBDOptionReply *reply,
150 Error **errp)
151 {
152 char *msg = NULL;
153 int result = -1;
154
155 if (!(reply->type & (1 << 31))) {
156 return 1;
157 }
158
159 if (reply->length) {
160 if (reply->length > NBD_MAX_BUFFER_SIZE) {
161 error_setg(errp, "server error %" PRIu32
162 " (%s) message is too long",
163 reply->type, nbd_rep_lookup(reply->type));
164 goto cleanup;
165 }
166 msg = g_malloc(reply->length + 1);
167 if (nbd_read(ioc, msg, reply->length, errp) < 0) {
168 error_prepend(errp, "failed to read option error %" PRIu32
169 " (%s) message: ",
170 reply->type, nbd_rep_lookup(reply->type));
171 goto cleanup;
172 }
173 msg[reply->length] = '\0';
174 }
175
176 switch (reply->type) {
177 case NBD_REP_ERR_UNSUP:
178 trace_nbd_reply_err_unsup(reply->option, nbd_opt_lookup(reply->option));
179 result = 0;
180 goto cleanup;
181
182 case NBD_REP_ERR_POLICY:
183 error_setg(errp, "Denied by server for option %" PRIu32 " (%s)",
184 reply->option, nbd_opt_lookup(reply->option));
185 break;
186
187 case NBD_REP_ERR_INVALID:
188 error_setg(errp, "Invalid parameters for option %" PRIu32 " (%s)",
189 reply->option, nbd_opt_lookup(reply->option));
190 break;
191
192 case NBD_REP_ERR_PLATFORM:
193 error_setg(errp, "Server lacks support for option %" PRIu32 " (%s)",
194 reply->option, nbd_opt_lookup(reply->option));
195 break;
196
197 case NBD_REP_ERR_TLS_REQD:
198 error_setg(errp, "TLS negotiation required before option %" PRIu32
199 " (%s)", reply->option, nbd_opt_lookup(reply->option));
200 break;
201
202 case NBD_REP_ERR_UNKNOWN:
203 error_setg(errp, "Requested export not available");
204 break;
205
206 case NBD_REP_ERR_SHUTDOWN:
207 error_setg(errp, "Server shutting down before option %" PRIu32 " (%s)",
208 reply->option, nbd_opt_lookup(reply->option));
209 break;
210
211 case NBD_REP_ERR_BLOCK_SIZE_REQD:
212 error_setg(errp, "Server requires INFO_BLOCK_SIZE for option %" PRIu32
213 " (%s)", reply->option, nbd_opt_lookup(reply->option));
214 break;
215
216 default:
217 error_setg(errp, "Unknown error code when asking for option %" PRIu32
218 " (%s)", reply->option, nbd_opt_lookup(reply->option));
219 break;
220 }
221
222 if (msg) {
223 error_append_hint(errp, "server reported: %s\n", msg);
224 }
225
226 cleanup:
227 g_free(msg);
228 if (result < 0) {
229 nbd_send_opt_abort(ioc);
230 }
231 return result;
232 }
233
234 /* Process another portion of the NBD_OPT_LIST reply. Set *@match if
235 * the current reply matches @want or if the server does not support
236 * NBD_OPT_LIST, otherwise leave @match alone. Return 0 if iteration
237 * is complete, positive if more replies are expected, or negative
238 * with @errp set if an unrecoverable error occurred. */
239 static int nbd_receive_list(QIOChannel *ioc, const char *want, bool *match,
240 Error **errp)
241 {
242 NBDOptionReply reply;
243 uint32_t len;
244 uint32_t namelen;
245 char name[NBD_MAX_NAME_SIZE + 1];
246 int error;
247
248 if (nbd_receive_option_reply(ioc, NBD_OPT_LIST, &reply, errp) < 0) {
249 return -1;
250 }
251 error = nbd_handle_reply_err(ioc, &reply, errp);
252 if (error <= 0) {
253 /* The server did not support NBD_OPT_LIST, so set *match on
254 * the assumption that any name will be accepted. */
255 *match = true;
256 return error;
257 }
258 len = reply.length;
259
260 if (reply.type == NBD_REP_ACK) {
261 if (len != 0) {
262 error_setg(errp, "length too long for option end");
263 nbd_send_opt_abort(ioc);
264 return -1;
265 }
266 return 0;
267 } else if (reply.type != NBD_REP_SERVER) {
268 error_setg(errp, "Unexpected reply type %" PRIx32 " expected %x",
269 reply.type, NBD_REP_SERVER);
270 nbd_send_opt_abort(ioc);
271 return -1;
272 }
273
274 if (len < sizeof(namelen) || len > NBD_MAX_BUFFER_SIZE) {
275 error_setg(errp, "incorrect option length %" PRIu32, len);
276 nbd_send_opt_abort(ioc);
277 return -1;
278 }
279 if (nbd_read(ioc, &namelen, sizeof(namelen), errp) < 0) {
280 error_prepend(errp, "failed to read option name length: ");
281 nbd_send_opt_abort(ioc);
282 return -1;
283 }
284 namelen = be32_to_cpu(namelen);
285 len -= sizeof(namelen);
286 if (len < namelen) {
287 error_setg(errp, "incorrect option name length");
288 nbd_send_opt_abort(ioc);
289 return -1;
290 }
291 if (namelen != strlen(want)) {
292 if (nbd_drop(ioc, len, errp) < 0) {
293 error_prepend(errp,
294 "failed to skip export name with wrong length: ");
295 nbd_send_opt_abort(ioc);
296 return -1;
297 }
298 return 1;
299 }
300
301 assert(namelen < sizeof(name));
302 if (nbd_read(ioc, name, namelen, errp) < 0) {
303 error_prepend(errp, "failed to read export name: ");
304 nbd_send_opt_abort(ioc);
305 return -1;
306 }
307 name[namelen] = '\0';
308 len -= namelen;
309 if (nbd_drop(ioc, len, errp) < 0) {
310 error_prepend(errp, "failed to read export description: ");
311 nbd_send_opt_abort(ioc);
312 return -1;
313 }
314 if (!strcmp(name, want)) {
315 *match = true;
316 }
317 return 1;
318 }
319
320
321 /* Returns -1 if NBD_OPT_GO proves the export @wantname cannot be
322 * used, 0 if NBD_OPT_GO is unsupported (fall back to NBD_OPT_LIST and
323 * NBD_OPT_EXPORT_NAME in that case), and > 0 if the export is good to
324 * go (with @info populated). */
325 static int nbd_opt_go(QIOChannel *ioc, const char *wantname,
326 NBDExportInfo *info, Error **errp)
327 {
328 NBDOptionReply reply;
329 uint32_t len = strlen(wantname);
330 uint16_t type;
331 int error;
332 char *buf;
333
334 /* The protocol requires that the server send NBD_INFO_EXPORT with
335 * a non-zero flags (at least NBD_FLAG_HAS_FLAGS must be set); so
336 * flags still 0 is a witness of a broken server. */
337 info->flags = 0;
338
339 trace_nbd_opt_go_start(wantname);
340 buf = g_malloc(4 + len + 2 + 2 * info->request_sizes + 1);
341 stl_be_p(buf, len);
342 memcpy(buf + 4, wantname, len);
343 /* At most one request, everything else up to server */
344 stw_be_p(buf + 4 + len, info->request_sizes);
345 if (info->request_sizes) {
346 stw_be_p(buf + 4 + len + 2, NBD_INFO_BLOCK_SIZE);
347 }
348 error = nbd_send_option_request(ioc, NBD_OPT_GO,
349 4 + len + 2 + 2 * info->request_sizes,
350 buf, errp);
351 g_free(buf);
352 if (error < 0) {
353 return -1;
354 }
355
356 while (1) {
357 if (nbd_receive_option_reply(ioc, NBD_OPT_GO, &reply, errp) < 0) {
358 return -1;
359 }
360 error = nbd_handle_reply_err(ioc, &reply, errp);
361 if (error <= 0) {
362 return error;
363 }
364 len = reply.length;
365
366 if (reply.type == NBD_REP_ACK) {
367 /* Server is done sending info and moved into transmission
368 phase, but make sure it sent flags */
369 if (len) {
370 error_setg(errp, "server sent invalid NBD_REP_ACK");
371 return -1;
372 }
373 if (!info->flags) {
374 error_setg(errp, "broken server omitted NBD_INFO_EXPORT");
375 return -1;
376 }
377 trace_nbd_opt_go_success();
378 return 1;
379 }
380 if (reply.type != NBD_REP_INFO) {
381 error_setg(errp, "unexpected reply type %" PRIu32
382 " (%s), expected %u",
383 reply.type, nbd_rep_lookup(reply.type), NBD_REP_INFO);
384 nbd_send_opt_abort(ioc);
385 return -1;
386 }
387 if (len < sizeof(type)) {
388 error_setg(errp, "NBD_REP_INFO length %" PRIu32 " is too short",
389 len);
390 nbd_send_opt_abort(ioc);
391 return -1;
392 }
393 if (nbd_read(ioc, &type, sizeof(type), errp) < 0) {
394 error_prepend(errp, "failed to read info type: ");
395 nbd_send_opt_abort(ioc);
396 return -1;
397 }
398 len -= sizeof(type);
399 be16_to_cpus(&type);
400 switch (type) {
401 case NBD_INFO_EXPORT:
402 if (len != sizeof(info->size) + sizeof(info->flags)) {
403 error_setg(errp, "remaining export info len %" PRIu32
404 " is unexpected size", len);
405 nbd_send_opt_abort(ioc);
406 return -1;
407 }
408 if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
409 error_prepend(errp, "failed to read info size: ");
410 nbd_send_opt_abort(ioc);
411 return -1;
412 }
413 be64_to_cpus(&info->size);
414 if (nbd_read(ioc, &info->flags, sizeof(info->flags), errp) < 0) {
415 error_prepend(errp, "failed to read info flags: ");
416 nbd_send_opt_abort(ioc);
417 return -1;
418 }
419 be16_to_cpus(&info->flags);
420 trace_nbd_receive_negotiate_size_flags(info->size, info->flags);
421 break;
422
423 case NBD_INFO_BLOCK_SIZE:
424 if (len != sizeof(info->min_block) * 3) {
425 error_setg(errp, "remaining export info len %" PRIu32
426 " is unexpected size", len);
427 nbd_send_opt_abort(ioc);
428 return -1;
429 }
430 if (nbd_read(ioc, &info->min_block, sizeof(info->min_block),
431 errp) < 0) {
432 error_prepend(errp, "failed to read info minimum block size: ");
433 nbd_send_opt_abort(ioc);
434 return -1;
435 }
436 be32_to_cpus(&info->min_block);
437 if (!is_power_of_2(info->min_block)) {
438 error_setg(errp, "server minimum block size %" PRId32
439 "is not a power of two", info->min_block);
440 nbd_send_opt_abort(ioc);
441 return -1;
442 }
443 if (nbd_read(ioc, &info->opt_block, sizeof(info->opt_block),
444 errp) < 0) {
445 error_prepend(errp,
446 "failed to read info preferred block size: ");
447 nbd_send_opt_abort(ioc);
448 return -1;
449 }
450 be32_to_cpus(&info->opt_block);
451 if (!is_power_of_2(info->opt_block) ||
452 info->opt_block < info->min_block) {
453 error_setg(errp, "server preferred block size %" PRId32
454 "is not valid", info->opt_block);
455 nbd_send_opt_abort(ioc);
456 return -1;
457 }
458 if (nbd_read(ioc, &info->max_block, sizeof(info->max_block),
459 errp) < 0) {
460 error_prepend(errp, "failed to read info maximum block size: ");
461 nbd_send_opt_abort(ioc);
462 return -1;
463 }
464 be32_to_cpus(&info->max_block);
465 trace_nbd_opt_go_info_block_size(info->min_block, info->opt_block,
466 info->max_block);
467 break;
468
469 default:
470 trace_nbd_opt_go_info_unknown(type, nbd_info_lookup(type));
471 if (nbd_drop(ioc, len, errp) < 0) {
472 error_prepend(errp, "Failed to read info payload: ");
473 nbd_send_opt_abort(ioc);
474 return -1;
475 }
476 break;
477 }
478 }
479 }
480
481 /* Return -1 on failure, 0 if wantname is an available export. */
482 static int nbd_receive_query_exports(QIOChannel *ioc,
483 const char *wantname,
484 Error **errp)
485 {
486 bool foundExport = false;
487
488 trace_nbd_receive_query_exports_start(wantname);
489 if (nbd_send_option_request(ioc, NBD_OPT_LIST, 0, NULL, errp) < 0) {
490 return -1;
491 }
492
493 while (1) {
494 int ret = nbd_receive_list(ioc, wantname, &foundExport, errp);
495
496 if (ret < 0) {
497 /* Server gave unexpected reply */
498 return -1;
499 } else if (ret == 0) {
500 /* Done iterating. */
501 if (!foundExport) {
502 error_setg(errp, "No export with name '%s' available",
503 wantname);
504 nbd_send_opt_abort(ioc);
505 return -1;
506 }
507 trace_nbd_receive_query_exports_success(wantname);
508 return 0;
509 }
510 }
511 }
512
513 /* nbd_request_simple_option: Send an option request, and parse the reply
514 * return 1 for successful negotiation,
515 * 0 if operation is unsupported,
516 * -1 with errp set for any other error
517 */
518 static int nbd_request_simple_option(QIOChannel *ioc, int opt, Error **errp)
519 {
520 NBDOptionReply reply;
521 int error;
522
523 if (nbd_send_option_request(ioc, opt, 0, NULL, errp) < 0) {
524 return -1;
525 }
526
527 if (nbd_receive_option_reply(ioc, opt, &reply, errp) < 0) {
528 return -1;
529 }
530 error = nbd_handle_reply_err(ioc, &reply, errp);
531 if (error <= 0) {
532 return error;
533 }
534
535 if (reply.type != NBD_REP_ACK) {
536 error_setg(errp, "Server answered option %d (%s) with unexpected "
537 "reply %" PRIu32 " (%s)", opt, nbd_opt_lookup(opt),
538 reply.type, nbd_rep_lookup(reply.type));
539 nbd_send_opt_abort(ioc);
540 return -1;
541 }
542
543 if (reply.length != 0) {
544 error_setg(errp, "Option %d ('%s') response length is %" PRIu32
545 " (it should be zero)", opt, nbd_opt_lookup(opt),
546 reply.length);
547 nbd_send_opt_abort(ioc);
548 return -1;
549 }
550
551 return 1;
552 }
553
554 static QIOChannel *nbd_receive_starttls(QIOChannel *ioc,
555 QCryptoTLSCreds *tlscreds,
556 const char *hostname, Error **errp)
557 {
558 int ret;
559 QIOChannelTLS *tioc;
560 struct NBDTLSHandshakeData data = { 0 };
561
562 ret = nbd_request_simple_option(ioc, NBD_OPT_STARTTLS, errp);
563 if (ret <= 0) {
564 if (ret == 0) {
565 error_setg(errp, "Server don't support STARTTLS option");
566 nbd_send_opt_abort(ioc);
567 }
568 return NULL;
569 }
570
571 trace_nbd_receive_starttls_new_client();
572 tioc = qio_channel_tls_new_client(ioc, tlscreds, hostname, errp);
573 if (!tioc) {
574 return NULL;
575 }
576 qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-client-tls");
577 data.loop = g_main_loop_new(g_main_context_default(), FALSE);
578 trace_nbd_receive_starttls_tls_handshake();
579 qio_channel_tls_handshake(tioc,
580 nbd_tls_handshake,
581 &data,
582 NULL,
583 NULL);
584
585 if (!data.complete) {
586 g_main_loop_run(data.loop);
587 }
588 g_main_loop_unref(data.loop);
589 if (data.error) {
590 error_propagate(errp, data.error);
591 object_unref(OBJECT(tioc));
592 return NULL;
593 }
594
595 return QIO_CHANNEL(tioc);
596 }
597
598
599 int nbd_receive_negotiate(QIOChannel *ioc, const char *name,
600 QCryptoTLSCreds *tlscreds, const char *hostname,
601 QIOChannel **outioc, NBDExportInfo *info,
602 Error **errp)
603 {
604 char buf[256];
605 uint64_t magic;
606 int rc;
607 bool zeroes = true;
608 bool structured_reply = info->structured_reply;
609
610 trace_nbd_receive_negotiate(tlscreds, hostname ? hostname : "<null>");
611
612 info->structured_reply = false;
613 rc = -EINVAL;
614
615 if (outioc) {
616 *outioc = NULL;
617 }
618 if (tlscreds && !outioc) {
619 error_setg(errp, "Output I/O channel required for TLS");
620 goto fail;
621 }
622
623 if (nbd_read(ioc, buf, 8, errp) < 0) {
624 error_prepend(errp, "Failed to read data: ");
625 goto fail;
626 }
627
628 buf[8] = '\0';
629 if (strlen(buf) == 0) {
630 error_setg(errp, "Server connection closed unexpectedly");
631 goto fail;
632 }
633
634 magic = ldq_be_p(buf);
635 trace_nbd_receive_negotiate_magic(magic);
636
637 if (memcmp(buf, "NBDMAGIC", 8) != 0) {
638 error_setg(errp, "Invalid magic received");
639 goto fail;
640 }
641
642 if (nbd_read(ioc, &magic, sizeof(magic), errp) < 0) {
643 error_prepend(errp, "Failed to read magic: ");
644 goto fail;
645 }
646 magic = be64_to_cpu(magic);
647 trace_nbd_receive_negotiate_magic(magic);
648
649 if (magic == NBD_OPTS_MAGIC) {
650 uint32_t clientflags = 0;
651 uint16_t globalflags;
652 bool fixedNewStyle = false;
653
654 if (nbd_read(ioc, &globalflags, sizeof(globalflags), errp) < 0) {
655 error_prepend(errp, "Failed to read server flags: ");
656 goto fail;
657 }
658 globalflags = be16_to_cpu(globalflags);
659 trace_nbd_receive_negotiate_server_flags(globalflags);
660 if (globalflags & NBD_FLAG_FIXED_NEWSTYLE) {
661 fixedNewStyle = true;
662 clientflags |= NBD_FLAG_C_FIXED_NEWSTYLE;
663 }
664 if (globalflags & NBD_FLAG_NO_ZEROES) {
665 zeroes = false;
666 clientflags |= NBD_FLAG_C_NO_ZEROES;
667 }
668 /* client requested flags */
669 clientflags = cpu_to_be32(clientflags);
670 if (nbd_write(ioc, &clientflags, sizeof(clientflags), errp) < 0) {
671 error_prepend(errp, "Failed to send clientflags field: ");
672 goto fail;
673 }
674 if (tlscreds) {
675 if (fixedNewStyle) {
676 *outioc = nbd_receive_starttls(ioc, tlscreds, hostname, errp);
677 if (!*outioc) {
678 goto fail;
679 }
680 ioc = *outioc;
681 } else {
682 error_setg(errp, "Server does not support STARTTLS");
683 goto fail;
684 }
685 }
686 if (!name) {
687 trace_nbd_receive_negotiate_default_name();
688 name = "";
689 }
690 if (fixedNewStyle) {
691 int result;
692
693 if (structured_reply) {
694 result = nbd_request_simple_option(ioc,
695 NBD_OPT_STRUCTURED_REPLY,
696 errp);
697 if (result < 0) {
698 goto fail;
699 }
700 info->structured_reply = result == 1;
701 }
702
703 /* Try NBD_OPT_GO first - if it works, we are done (it
704 * also gives us a good message if the server requires
705 * TLS). If it is not available, fall back to
706 * NBD_OPT_LIST for nicer error messages about a missing
707 * export, then use NBD_OPT_EXPORT_NAME. */
708 result = nbd_opt_go(ioc, name, info, errp);
709 if (result < 0) {
710 goto fail;
711 }
712 if (result > 0) {
713 return 0;
714 }
715 /* Check our desired export is present in the
716 * server export list. Since NBD_OPT_EXPORT_NAME
717 * cannot return an error message, running this
718 * query gives us better error reporting if the
719 * export name is not available.
720 */
721 if (nbd_receive_query_exports(ioc, name, errp) < 0) {
722 goto fail;
723 }
724 }
725 /* write the export name request */
726 if (nbd_send_option_request(ioc, NBD_OPT_EXPORT_NAME, -1, name,
727 errp) < 0) {
728 goto fail;
729 }
730
731 /* Read the response */
732 if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
733 error_prepend(errp, "Failed to read export length: ");
734 goto fail;
735 }
736 be64_to_cpus(&info->size);
737
738 if (nbd_read(ioc, &info->flags, sizeof(info->flags), errp) < 0) {
739 error_prepend(errp, "Failed to read export flags: ");
740 goto fail;
741 }
742 be16_to_cpus(&info->flags);
743 } else if (magic == NBD_CLIENT_MAGIC) {
744 uint32_t oldflags;
745
746 if (name) {
747 error_setg(errp, "Server does not support export names");
748 goto fail;
749 }
750 if (tlscreds) {
751 error_setg(errp, "Server does not support STARTTLS");
752 goto fail;
753 }
754
755 if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
756 error_prepend(errp, "Failed to read export length: ");
757 goto fail;
758 }
759 be64_to_cpus(&info->size);
760
761 if (nbd_read(ioc, &oldflags, sizeof(oldflags), errp) < 0) {
762 error_prepend(errp, "Failed to read export flags: ");
763 goto fail;
764 }
765 be32_to_cpus(&oldflags);
766 if (oldflags & ~0xffff) {
767 error_setg(errp, "Unexpected export flags %0x" PRIx32, oldflags);
768 goto fail;
769 }
770 info->flags = oldflags;
771 } else {
772 error_setg(errp, "Bad magic received");
773 goto fail;
774 }
775
776 trace_nbd_receive_negotiate_size_flags(info->size, info->flags);
777 if (zeroes && nbd_drop(ioc, 124, errp) < 0) {
778 error_prepend(errp, "Failed to read reserved block: ");
779 goto fail;
780 }
781 rc = 0;
782
783 fail:
784 return rc;
785 }
786
787 #ifdef __linux__
788 int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info,
789 Error **errp)
790 {
791 unsigned long sector_size = MAX(BDRV_SECTOR_SIZE, info->min_block);
792 unsigned long sectors = info->size / sector_size;
793
794 /* FIXME: Once the kernel module is patched to honor block sizes,
795 * and to advertise that fact to user space, we should update the
796 * hand-off to the kernel to use any block sizes we learned. */
797 assert(!info->request_sizes);
798 if (info->size / sector_size != sectors) {
799 error_setg(errp, "Export size %" PRIu64 " too large for 32-bit kernel",
800 info->size);
801 return -E2BIG;
802 }
803
804 trace_nbd_init_set_socket();
805
806 if (ioctl(fd, NBD_SET_SOCK, (unsigned long) sioc->fd) < 0) {
807 int serrno = errno;
808 error_setg(errp, "Failed to set NBD socket");
809 return -serrno;
810 }
811
812 trace_nbd_init_set_block_size(sector_size);
813
814 if (ioctl(fd, NBD_SET_BLKSIZE, sector_size) < 0) {
815 int serrno = errno;
816 error_setg(errp, "Failed setting NBD block size");
817 return -serrno;
818 }
819
820 trace_nbd_init_set_size(sectors);
821 if (info->size % sector_size) {
822 trace_nbd_init_trailing_bytes(info->size % sector_size);
823 }
824
825 if (ioctl(fd, NBD_SET_SIZE_BLOCKS, sectors) < 0) {
826 int serrno = errno;
827 error_setg(errp, "Failed setting size (in blocks)");
828 return -serrno;
829 }
830
831 if (ioctl(fd, NBD_SET_FLAGS, (unsigned long) info->flags) < 0) {
832 if (errno == ENOTTY) {
833 int read_only = (info->flags & NBD_FLAG_READ_ONLY) != 0;
834 trace_nbd_init_set_readonly();
835
836 if (ioctl(fd, BLKROSET, (unsigned long) &read_only) < 0) {
837 int serrno = errno;
838 error_setg(errp, "Failed setting read-only attribute");
839 return -serrno;
840 }
841 } else {
842 int serrno = errno;
843 error_setg(errp, "Failed setting flags");
844 return -serrno;
845 }
846 }
847
848 trace_nbd_init_finish();
849
850 return 0;
851 }
852
853 int nbd_client(int fd)
854 {
855 int ret;
856 int serrno;
857
858 trace_nbd_client_loop();
859
860 ret = ioctl(fd, NBD_DO_IT);
861 if (ret < 0 && errno == EPIPE) {
862 /* NBD_DO_IT normally returns EPIPE when someone has disconnected
863 * the socket via NBD_DISCONNECT. We do not want to return 1 in
864 * that case.
865 */
866 ret = 0;
867 }
868 serrno = errno;
869
870 trace_nbd_client_loop_ret(ret, strerror(serrno));
871
872 trace_nbd_client_clear_queue();
873 ioctl(fd, NBD_CLEAR_QUE);
874
875 trace_nbd_client_clear_socket();
876 ioctl(fd, NBD_CLEAR_SOCK);
877
878 errno = serrno;
879 return ret;
880 }
881
882 int nbd_disconnect(int fd)
883 {
884 ioctl(fd, NBD_CLEAR_QUE);
885 ioctl(fd, NBD_DISCONNECT);
886 ioctl(fd, NBD_CLEAR_SOCK);
887 return 0;
888 }
889
890 #else
891 int nbd_init(int fd, QIOChannelSocket *ioc, NBDExportInfo *info,
892 Error **errp)
893 {
894 error_setg(errp, "nbd_init is only supported on Linux");
895 return -ENOTSUP;
896 }
897
898 int nbd_client(int fd)
899 {
900 return -ENOTSUP;
901 }
902 int nbd_disconnect(int fd)
903 {
904 return -ENOTSUP;
905 }
906 #endif
907
908 int nbd_send_request(QIOChannel *ioc, NBDRequest *request)
909 {
910 uint8_t buf[NBD_REQUEST_SIZE];
911
912 trace_nbd_send_request(request->from, request->len, request->handle,
913 request->flags, request->type,
914 nbd_cmd_lookup(request->type));
915
916 stl_be_p(buf, NBD_REQUEST_MAGIC);
917 stw_be_p(buf + 4, request->flags);
918 stw_be_p(buf + 6, request->type);
919 stq_be_p(buf + 8, request->handle);
920 stq_be_p(buf + 16, request->from);
921 stl_be_p(buf + 24, request->len);
922
923 return nbd_write(ioc, buf, sizeof(buf), NULL);
924 }
925
926 /* nbd_receive_simple_reply
927 * Read simple reply except magic field (which should be already read).
928 * Payload is not read (payload is possible for CMD_READ, but here we even
929 * don't know whether it take place or not).
930 */
931 static int nbd_receive_simple_reply(QIOChannel *ioc, NBDSimpleReply *reply,
932 Error **errp)
933 {
934 int ret;
935
936 assert(reply->magic == NBD_SIMPLE_REPLY_MAGIC);
937
938 ret = nbd_read(ioc, (uint8_t *)reply + sizeof(reply->magic),
939 sizeof(*reply) - sizeof(reply->magic), errp);
940 if (ret < 0) {
941 return ret;
942 }
943
944 be32_to_cpus(&reply->error);
945 be64_to_cpus(&reply->handle);
946
947 return 0;
948 }
949
950 /* nbd_receive_structured_reply_chunk
951 * Read structured reply chunk except magic field (which should be already
952 * read).
953 * Payload is not read.
954 */
955 static int nbd_receive_structured_reply_chunk(QIOChannel *ioc,
956 NBDStructuredReplyChunk *chunk,
957 Error **errp)
958 {
959 int ret;
960
961 assert(chunk->magic == NBD_STRUCTURED_REPLY_MAGIC);
962
963 ret = nbd_read(ioc, (uint8_t *)chunk + sizeof(chunk->magic),
964 sizeof(*chunk) - sizeof(chunk->magic), errp);
965 if (ret < 0) {
966 return ret;
967 }
968
969 be16_to_cpus(&chunk->flags);
970 be16_to_cpus(&chunk->type);
971 be64_to_cpus(&chunk->handle);
972 be32_to_cpus(&chunk->length);
973
974 return 0;
975 }
976
977 /* nbd_receive_reply
978 * Returns 1 on success
979 * 0 on eof, when no data was read (errp is not set)
980 * negative errno on failure (errp is set)
981 */
982 int nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp)
983 {
984 int ret;
985 const char *type;
986
987 ret = nbd_read_eof(ioc, &reply->magic, sizeof(reply->magic), errp);
988 if (ret <= 0) {
989 return ret;
990 }
991
992 be32_to_cpus(&reply->magic);
993
994 switch (reply->magic) {
995 case NBD_SIMPLE_REPLY_MAGIC:
996 ret = nbd_receive_simple_reply(ioc, &reply->simple, errp);
997 if (ret < 0) {
998 break;
999 }
1000 trace_nbd_receive_simple_reply(reply->simple.error,
1001 nbd_err_lookup(reply->simple.error),
1002 reply->handle);
1003 break;
1004 case NBD_STRUCTURED_REPLY_MAGIC:
1005 ret = nbd_receive_structured_reply_chunk(ioc, &reply->structured, errp);
1006 if (ret < 0) {
1007 break;
1008 }
1009 type = nbd_reply_type_lookup(reply->structured.type);
1010 trace_nbd_receive_structured_reply_chunk(reply->structured.flags,
1011 reply->structured.type, type,
1012 reply->structured.handle,
1013 reply->structured.length);
1014 break;
1015 default:
1016 error_setg(errp, "invalid magic (got 0x%" PRIx32 ")", reply->magic);
1017 return -EINVAL;
1018 }
1019 if (ret < 0) {
1020 return ret;
1021 }
1022
1023 return 1;
1024 }
1025