nbd: Avoid magic number for NBD max name size
[qemu.git] / nbd / server.c
1 /*
2 * Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws>
3 *
4 * Network Block Device Server Side
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; under version 2 of the License.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, see <http://www.gnu.org/licenses/>.
17 */
18
19 #include "qemu/osdep.h"
20 #include "qapi/error.h"
21 #include "nbd-internal.h"
22
23 static int system_errno_to_nbd_errno(int err)
24 {
25 switch (err) {
26 case 0:
27 return NBD_SUCCESS;
28 case EPERM:
29 case EROFS:
30 return NBD_EPERM;
31 case EIO:
32 return NBD_EIO;
33 case ENOMEM:
34 return NBD_ENOMEM;
35 #ifdef EDQUOT
36 case EDQUOT:
37 #endif
38 case EFBIG:
39 case ENOSPC:
40 return NBD_ENOSPC;
41 case EINVAL:
42 default:
43 return NBD_EINVAL;
44 }
45 }
46
47 /* Definitions for opaque data types */
48
49 typedef struct NBDRequest NBDRequest;
50
51 struct NBDRequest {
52 QSIMPLEQ_ENTRY(NBDRequest) entry;
53 NBDClient *client;
54 uint8_t *data;
55 bool complete;
56 };
57
58 struct NBDExport {
59 int refcount;
60 void (*close)(NBDExport *exp);
61
62 BlockBackend *blk;
63 char *name;
64 off_t dev_offset;
65 off_t size;
66 uint32_t nbdflags;
67 QTAILQ_HEAD(, NBDClient) clients;
68 QTAILQ_ENTRY(NBDExport) next;
69
70 AioContext *ctx;
71
72 Notifier eject_notifier;
73 };
74
75 static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
76
77 struct NBDClient {
78 int refcount;
79 void (*close)(NBDClient *client);
80
81 NBDExport *exp;
82 QCryptoTLSCreds *tlscreds;
83 char *tlsaclname;
84 QIOChannelSocket *sioc; /* The underlying data channel */
85 QIOChannel *ioc; /* The current I/O channel which may differ (eg TLS) */
86
87 Coroutine *recv_coroutine;
88
89 CoMutex send_lock;
90 Coroutine *send_coroutine;
91
92 bool can_read;
93
94 QTAILQ_ENTRY(NBDClient) next;
95 int nb_requests;
96 bool closing;
97 };
98
99 /* That's all folks */
100
101 static void nbd_set_handlers(NBDClient *client);
102 static void nbd_unset_handlers(NBDClient *client);
103 static void nbd_update_can_read(NBDClient *client);
104
105 static gboolean nbd_negotiate_continue(QIOChannel *ioc,
106 GIOCondition condition,
107 void *opaque)
108 {
109 qemu_coroutine_enter(opaque, NULL);
110 return TRUE;
111 }
112
113 static ssize_t nbd_negotiate_read(QIOChannel *ioc, void *buffer, size_t size)
114 {
115 ssize_t ret;
116 guint watch;
117
118 assert(qemu_in_coroutine());
119 /* Negotiation are always in main loop. */
120 watch = qio_channel_add_watch(ioc,
121 G_IO_IN,
122 nbd_negotiate_continue,
123 qemu_coroutine_self(),
124 NULL);
125 ret = read_sync(ioc, buffer, size);
126 g_source_remove(watch);
127 return ret;
128
129 }
130
131 static ssize_t nbd_negotiate_write(QIOChannel *ioc, void *buffer, size_t size)
132 {
133 ssize_t ret;
134 guint watch;
135
136 assert(qemu_in_coroutine());
137 /* Negotiation are always in main loop. */
138 watch = qio_channel_add_watch(ioc,
139 G_IO_OUT,
140 nbd_negotiate_continue,
141 qemu_coroutine_self(),
142 NULL);
143 ret = write_sync(ioc, buffer, size);
144 g_source_remove(watch);
145 return ret;
146 }
147
148 static ssize_t nbd_negotiate_drop_sync(QIOChannel *ioc, size_t size)
149 {
150 ssize_t ret, dropped = size;
151 uint8_t *buffer = g_malloc(MIN(65536, size));
152
153 while (size > 0) {
154 ret = nbd_negotiate_read(ioc, buffer, MIN(65536, size));
155 if (ret < 0) {
156 g_free(buffer);
157 return ret;
158 }
159
160 assert(ret <= size);
161 size -= ret;
162 }
163
164 g_free(buffer);
165 return dropped;
166 }
167
168 /* Basic flow for negotiation
169
170 Server Client
171 Negotiate
172
173 or
174
175 Server Client
176 Negotiate #1
177 Option
178 Negotiate #2
179
180 ----
181
182 followed by
183
184 Server Client
185 Request
186 Response
187 Request
188 Response
189 ...
190 ...
191 Request (type == 2)
192
193 */
194
195 static int nbd_negotiate_send_rep(QIOChannel *ioc, uint32_t type, uint32_t opt)
196 {
197 uint64_t magic;
198 uint32_t len;
199
200 TRACE("Reply opt=%" PRIx32 " type=%" PRIx32, type, opt);
201
202 magic = cpu_to_be64(NBD_REP_MAGIC);
203 if (nbd_negotiate_write(ioc, &magic, sizeof(magic)) != sizeof(magic)) {
204 LOG("write failed (rep magic)");
205 return -EINVAL;
206 }
207 opt = cpu_to_be32(opt);
208 if (nbd_negotiate_write(ioc, &opt, sizeof(opt)) != sizeof(opt)) {
209 LOG("write failed (rep opt)");
210 return -EINVAL;
211 }
212 type = cpu_to_be32(type);
213 if (nbd_negotiate_write(ioc, &type, sizeof(type)) != sizeof(type)) {
214 LOG("write failed (rep type)");
215 return -EINVAL;
216 }
217 len = cpu_to_be32(0);
218 if (nbd_negotiate_write(ioc, &len, sizeof(len)) != sizeof(len)) {
219 LOG("write failed (rep data length)");
220 return -EINVAL;
221 }
222 return 0;
223 }
224
225 static int nbd_negotiate_send_rep_list(QIOChannel *ioc, NBDExport *exp)
226 {
227 uint64_t magic, name_len;
228 uint32_t opt, type, len;
229
230 TRACE("Advertising export name '%s'", exp->name ? exp->name : "");
231 name_len = strlen(exp->name);
232 magic = cpu_to_be64(NBD_REP_MAGIC);
233 if (nbd_negotiate_write(ioc, &magic, sizeof(magic)) != sizeof(magic)) {
234 LOG("write failed (magic)");
235 return -EINVAL;
236 }
237 opt = cpu_to_be32(NBD_OPT_LIST);
238 if (nbd_negotiate_write(ioc, &opt, sizeof(opt)) != sizeof(opt)) {
239 LOG("write failed (opt)");
240 return -EINVAL;
241 }
242 type = cpu_to_be32(NBD_REP_SERVER);
243 if (nbd_negotiate_write(ioc, &type, sizeof(type)) != sizeof(type)) {
244 LOG("write failed (reply type)");
245 return -EINVAL;
246 }
247 len = cpu_to_be32(name_len + sizeof(len));
248 if (nbd_negotiate_write(ioc, &len, sizeof(len)) != sizeof(len)) {
249 LOG("write failed (length)");
250 return -EINVAL;
251 }
252 len = cpu_to_be32(name_len);
253 if (nbd_negotiate_write(ioc, &len, sizeof(len)) != sizeof(len)) {
254 LOG("write failed (length)");
255 return -EINVAL;
256 }
257 if (nbd_negotiate_write(ioc, exp->name, name_len) != name_len) {
258 LOG("write failed (buffer)");
259 return -EINVAL;
260 }
261 return 0;
262 }
263
264 static int nbd_negotiate_handle_list(NBDClient *client, uint32_t length)
265 {
266 NBDExport *exp;
267
268 if (length) {
269 if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
270 return -EIO;
271 }
272 return nbd_negotiate_send_rep(client->ioc,
273 NBD_REP_ERR_INVALID, NBD_OPT_LIST);
274 }
275
276 /* For each export, send a NBD_REP_SERVER reply. */
277 QTAILQ_FOREACH(exp, &exports, next) {
278 if (nbd_negotiate_send_rep_list(client->ioc, exp)) {
279 return -EINVAL;
280 }
281 }
282 /* Finish with a NBD_REP_ACK. */
283 return nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, NBD_OPT_LIST);
284 }
285
286 static int nbd_negotiate_handle_export_name(NBDClient *client, uint32_t length)
287 {
288 int rc = -EINVAL;
289 char name[NBD_MAX_NAME_SIZE + 1];
290
291 /* Client sends:
292 [20 .. xx] export name (length bytes)
293 */
294 TRACE("Checking length");
295 if (length >= sizeof(name)) {
296 LOG("Bad length received");
297 goto fail;
298 }
299 if (nbd_negotiate_read(client->ioc, name, length) != length) {
300 LOG("read failed");
301 goto fail;
302 }
303 name[length] = '\0';
304
305 TRACE("Client requested export '%s'", name);
306
307 client->exp = nbd_export_find(name);
308 if (!client->exp) {
309 LOG("export not found");
310 goto fail;
311 }
312
313 QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
314 nbd_export_get(client->exp);
315 rc = 0;
316 fail:
317 return rc;
318 }
319
320
321 static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client,
322 uint32_t length)
323 {
324 QIOChannel *ioc;
325 QIOChannelTLS *tioc;
326 struct NBDTLSHandshakeData data = { 0 };
327
328 TRACE("Setting up TLS");
329 ioc = client->ioc;
330 if (length) {
331 if (nbd_negotiate_drop_sync(ioc, length) != length) {
332 return NULL;
333 }
334 nbd_negotiate_send_rep(ioc, NBD_REP_ERR_INVALID, NBD_OPT_STARTTLS);
335 return NULL;
336 }
337
338 if (nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK,
339 NBD_OPT_STARTTLS) < 0) {
340 return NULL;
341 }
342
343 tioc = qio_channel_tls_new_server(ioc,
344 client->tlscreds,
345 client->tlsaclname,
346 NULL);
347 if (!tioc) {
348 return NULL;
349 }
350
351 TRACE("Starting TLS handshake");
352 data.loop = g_main_loop_new(g_main_context_default(), FALSE);
353 qio_channel_tls_handshake(tioc,
354 nbd_tls_handshake,
355 &data,
356 NULL);
357
358 if (!data.complete) {
359 g_main_loop_run(data.loop);
360 }
361 g_main_loop_unref(data.loop);
362 if (data.error) {
363 object_unref(OBJECT(tioc));
364 error_free(data.error);
365 return NULL;
366 }
367
368 return QIO_CHANNEL(tioc);
369 }
370
371
372 static int nbd_negotiate_options(NBDClient *client)
373 {
374 uint32_t flags;
375 bool fixedNewstyle = false;
376
377 /* Client sends:
378 [ 0 .. 3] client flags
379
380 [ 0 .. 7] NBD_OPTS_MAGIC
381 [ 8 .. 11] NBD option
382 [12 .. 15] Data length
383 ... Rest of request
384
385 [ 0 .. 7] NBD_OPTS_MAGIC
386 [ 8 .. 11] Second NBD option
387 [12 .. 15] Data length
388 ... Rest of request
389 */
390
391 if (nbd_negotiate_read(client->ioc, &flags, sizeof(flags)) !=
392 sizeof(flags)) {
393 LOG("read failed");
394 return -EIO;
395 }
396 TRACE("Checking client flags");
397 be32_to_cpus(&flags);
398 if (flags & NBD_FLAG_C_FIXED_NEWSTYLE) {
399 TRACE("Client supports fixed newstyle handshake");
400 fixedNewstyle = true;
401 flags &= ~NBD_FLAG_C_FIXED_NEWSTYLE;
402 }
403 if (flags != 0) {
404 TRACE("Unknown client flags 0x%" PRIx32 " received", flags);
405 return -EIO;
406 }
407
408 while (1) {
409 int ret;
410 uint32_t clientflags, length;
411 uint64_t magic;
412
413 if (nbd_negotiate_read(client->ioc, &magic, sizeof(magic)) !=
414 sizeof(magic)) {
415 LOG("read failed");
416 return -EINVAL;
417 }
418 TRACE("Checking opts magic");
419 if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) {
420 LOG("Bad magic received");
421 return -EINVAL;
422 }
423
424 if (nbd_negotiate_read(client->ioc, &clientflags,
425 sizeof(clientflags)) != sizeof(clientflags)) {
426 LOG("read failed");
427 return -EINVAL;
428 }
429 clientflags = be32_to_cpu(clientflags);
430
431 if (nbd_negotiate_read(client->ioc, &length, sizeof(length)) !=
432 sizeof(length)) {
433 LOG("read failed");
434 return -EINVAL;
435 }
436 length = be32_to_cpu(length);
437
438 TRACE("Checking option 0x%" PRIx32, clientflags);
439 if (client->tlscreds &&
440 client->ioc == (QIOChannel *)client->sioc) {
441 QIOChannel *tioc;
442 if (!fixedNewstyle) {
443 TRACE("Unsupported option 0x%" PRIx32, clientflags);
444 return -EINVAL;
445 }
446 switch (clientflags) {
447 case NBD_OPT_STARTTLS:
448 tioc = nbd_negotiate_handle_starttls(client, length);
449 if (!tioc) {
450 return -EIO;
451 }
452 object_unref(OBJECT(client->ioc));
453 client->ioc = QIO_CHANNEL(tioc);
454 break;
455
456 case NBD_OPT_EXPORT_NAME:
457 /* No way to return an error to client, so drop connection */
458 TRACE("Option 0x%x not permitted before TLS", clientflags);
459 return -EINVAL;
460
461 default:
462 TRACE("Option 0x%" PRIx32 " not permitted before TLS",
463 clientflags);
464 if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
465 return -EIO;
466 }
467 ret = nbd_negotiate_send_rep(client->ioc, NBD_REP_ERR_TLS_REQD,
468 clientflags);
469 if (ret < 0) {
470 return ret;
471 }
472 break;
473 }
474 } else if (fixedNewstyle) {
475 switch (clientflags) {
476 case NBD_OPT_LIST:
477 ret = nbd_negotiate_handle_list(client, length);
478 if (ret < 0) {
479 return ret;
480 }
481 break;
482
483 case NBD_OPT_ABORT:
484 return -EINVAL;
485
486 case NBD_OPT_EXPORT_NAME:
487 return nbd_negotiate_handle_export_name(client, length);
488
489 case NBD_OPT_STARTTLS:
490 if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
491 return -EIO;
492 }
493 if (client->tlscreds) {
494 TRACE("TLS already enabled");
495 ret = nbd_negotiate_send_rep(client->ioc,
496 NBD_REP_ERR_INVALID,
497 clientflags);
498 } else {
499 TRACE("TLS not configured");
500 ret = nbd_negotiate_send_rep(client->ioc,
501 NBD_REP_ERR_POLICY,
502 clientflags);
503 }
504 if (ret < 0) {
505 return ret;
506 }
507 break;
508 default:
509 TRACE("Unsupported option 0x%" PRIx32, clientflags);
510 if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
511 return -EIO;
512 }
513 ret = nbd_negotiate_send_rep(client->ioc, NBD_REP_ERR_UNSUP,
514 clientflags);
515 if (ret < 0) {
516 return ret;
517 }
518 break;
519 }
520 } else {
521 /*
522 * If broken new-style we should drop the connection
523 * for anything except NBD_OPT_EXPORT_NAME
524 */
525 switch (clientflags) {
526 case NBD_OPT_EXPORT_NAME:
527 return nbd_negotiate_handle_export_name(client, length);
528
529 default:
530 TRACE("Unsupported option 0x%" PRIx32, clientflags);
531 return -EINVAL;
532 }
533 }
534 }
535 }
536
537 typedef struct {
538 NBDClient *client;
539 Coroutine *co;
540 } NBDClientNewData;
541
542 static coroutine_fn int nbd_negotiate(NBDClientNewData *data)
543 {
544 NBDClient *client = data->client;
545 char buf[8 + 8 + 8 + 128];
546 int rc;
547 const int myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM |
548 NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA);
549 bool oldStyle;
550
551 /* Old style negotiation header without options
552 [ 0 .. 7] passwd ("NBDMAGIC")
553 [ 8 .. 15] magic (NBD_CLIENT_MAGIC)
554 [16 .. 23] size
555 [24 .. 25] server flags (0)
556 [26 .. 27] export flags
557 [28 .. 151] reserved (0)
558
559 New style negotiation header with options
560 [ 0 .. 7] passwd ("NBDMAGIC")
561 [ 8 .. 15] magic (NBD_OPTS_MAGIC)
562 [16 .. 17] server flags (0)
563 ....options sent....
564 [18 .. 25] size
565 [26 .. 27] export flags
566 [28 .. 151] reserved (0)
567 */
568
569 qio_channel_set_blocking(client->ioc, false, NULL);
570 rc = -EINVAL;
571
572 TRACE("Beginning negotiation.");
573 memset(buf, 0, sizeof(buf));
574 memcpy(buf, "NBDMAGIC", 8);
575
576 oldStyle = client->exp != NULL && !client->tlscreds;
577 if (oldStyle) {
578 assert ((client->exp->nbdflags & ~65535) == 0);
579 TRACE("advertising size %" PRIu64 " and flags %x",
580 client->exp->size, client->exp->nbdflags | myflags);
581 stq_be_p(buf + 8, NBD_CLIENT_MAGIC);
582 stq_be_p(buf + 16, client->exp->size);
583 stw_be_p(buf + 26, client->exp->nbdflags | myflags);
584 } else {
585 stq_be_p(buf + 8, NBD_OPTS_MAGIC);
586 stw_be_p(buf + 16, NBD_FLAG_FIXED_NEWSTYLE);
587 }
588
589 if (oldStyle) {
590 if (client->tlscreds) {
591 TRACE("TLS cannot be enabled with oldstyle protocol");
592 goto fail;
593 }
594 if (nbd_negotiate_write(client->ioc, buf, sizeof(buf)) != sizeof(buf)) {
595 LOG("write failed");
596 goto fail;
597 }
598 } else {
599 if (nbd_negotiate_write(client->ioc, buf, 18) != 18) {
600 LOG("write failed");
601 goto fail;
602 }
603 rc = nbd_negotiate_options(client);
604 if (rc != 0) {
605 LOG("option negotiation failed");
606 goto fail;
607 }
608
609 assert ((client->exp->nbdflags & ~65535) == 0);
610 TRACE("advertising size %" PRIu64 " and flags %x",
611 client->exp->size, client->exp->nbdflags | myflags);
612 stq_be_p(buf + 18, client->exp->size);
613 stw_be_p(buf + 26, client->exp->nbdflags | myflags);
614 if (nbd_negotiate_write(client->ioc, buf + 18, sizeof(buf) - 18) !=
615 sizeof(buf) - 18) {
616 LOG("write failed");
617 goto fail;
618 }
619 }
620
621 TRACE("Negotiation succeeded.");
622 rc = 0;
623 fail:
624 return rc;
625 }
626
627 static ssize_t nbd_receive_request(QIOChannel *ioc, struct nbd_request *request)
628 {
629 uint8_t buf[NBD_REQUEST_SIZE];
630 uint32_t magic;
631 ssize_t ret;
632
633 ret = read_sync(ioc, buf, sizeof(buf));
634 if (ret < 0) {
635 return ret;
636 }
637
638 if (ret != sizeof(buf)) {
639 LOG("read failed");
640 return -EINVAL;
641 }
642
643 /* Request
644 [ 0 .. 3] magic (NBD_REQUEST_MAGIC)
645 [ 4 .. 7] type (0 == READ, 1 == WRITE)
646 [ 8 .. 15] handle
647 [16 .. 23] from
648 [24 .. 27] len
649 */
650
651 magic = ldl_be_p(buf);
652 request->type = ldl_be_p(buf + 4);
653 request->handle = ldq_be_p(buf + 8);
654 request->from = ldq_be_p(buf + 16);
655 request->len = ldl_be_p(buf + 24);
656
657 TRACE("Got request: { magic = 0x%" PRIx32 ", .type = %" PRIx32
658 ", from = %" PRIu64 " , len = %" PRIu32 " }",
659 magic, request->type, request->from, request->len);
660
661 if (magic != NBD_REQUEST_MAGIC) {
662 LOG("invalid magic (got 0x%" PRIx32 ")", magic);
663 return -EINVAL;
664 }
665 return 0;
666 }
667
668 static ssize_t nbd_send_reply(QIOChannel *ioc, struct nbd_reply *reply)
669 {
670 uint8_t buf[NBD_REPLY_SIZE];
671 ssize_t ret;
672
673 reply->error = system_errno_to_nbd_errno(reply->error);
674
675 TRACE("Sending response to client: { .error = %" PRId32
676 ", handle = %" PRIu64 " }",
677 reply->error, reply->handle);
678
679 /* Reply
680 [ 0 .. 3] magic (NBD_REPLY_MAGIC)
681 [ 4 .. 7] error (0 == no error)
682 [ 7 .. 15] handle
683 */
684 stl_be_p(buf, NBD_REPLY_MAGIC);
685 stl_be_p(buf + 4, reply->error);
686 stq_be_p(buf + 8, reply->handle);
687
688 ret = write_sync(ioc, buf, sizeof(buf));
689 if (ret < 0) {
690 return ret;
691 }
692
693 if (ret != sizeof(buf)) {
694 LOG("writing to socket failed");
695 return -EINVAL;
696 }
697 return 0;
698 }
699
700 #define MAX_NBD_REQUESTS 16
701
702 void nbd_client_get(NBDClient *client)
703 {
704 client->refcount++;
705 }
706
707 void nbd_client_put(NBDClient *client)
708 {
709 if (--client->refcount == 0) {
710 /* The last reference should be dropped by client->close,
711 * which is called by client_close.
712 */
713 assert(client->closing);
714
715 nbd_unset_handlers(client);
716 object_unref(OBJECT(client->sioc));
717 object_unref(OBJECT(client->ioc));
718 if (client->tlscreds) {
719 object_unref(OBJECT(client->tlscreds));
720 }
721 g_free(client->tlsaclname);
722 if (client->exp) {
723 QTAILQ_REMOVE(&client->exp->clients, client, next);
724 nbd_export_put(client->exp);
725 }
726 g_free(client);
727 }
728 }
729
730 static void client_close(NBDClient *client)
731 {
732 if (client->closing) {
733 return;
734 }
735
736 client->closing = true;
737
738 /* Force requests to finish. They will drop their own references,
739 * then we'll close the socket and free the NBDClient.
740 */
741 qio_channel_shutdown(client->ioc, QIO_CHANNEL_SHUTDOWN_BOTH,
742 NULL);
743
744 /* Also tell the client, so that they release their reference. */
745 if (client->close) {
746 client->close(client);
747 }
748 }
749
750 static NBDRequest *nbd_request_get(NBDClient *client)
751 {
752 NBDRequest *req;
753
754 assert(client->nb_requests <= MAX_NBD_REQUESTS - 1);
755 client->nb_requests++;
756 nbd_update_can_read(client);
757
758 req = g_new0(NBDRequest, 1);
759 nbd_client_get(client);
760 req->client = client;
761 return req;
762 }
763
764 static void nbd_request_put(NBDRequest *req)
765 {
766 NBDClient *client = req->client;
767
768 if (req->data) {
769 qemu_vfree(req->data);
770 }
771 g_free(req);
772
773 client->nb_requests--;
774 nbd_update_can_read(client);
775 nbd_client_put(client);
776 }
777
778 static void blk_aio_attached(AioContext *ctx, void *opaque)
779 {
780 NBDExport *exp = opaque;
781 NBDClient *client;
782
783 TRACE("Export %s: Attaching clients to AIO context %p\n", exp->name, ctx);
784
785 exp->ctx = ctx;
786
787 QTAILQ_FOREACH(client, &exp->clients, next) {
788 nbd_set_handlers(client);
789 }
790 }
791
792 static void blk_aio_detach(void *opaque)
793 {
794 NBDExport *exp = opaque;
795 NBDClient *client;
796
797 TRACE("Export %s: Detaching clients from AIO context %p\n", exp->name, exp->ctx);
798
799 QTAILQ_FOREACH(client, &exp->clients, next) {
800 nbd_unset_handlers(client);
801 }
802
803 exp->ctx = NULL;
804 }
805
806 static void nbd_eject_notifier(Notifier *n, void *data)
807 {
808 NBDExport *exp = container_of(n, NBDExport, eject_notifier);
809 nbd_export_close(exp);
810 }
811
812 NBDExport *nbd_export_new(BlockBackend *blk, off_t dev_offset, off_t size,
813 uint32_t nbdflags, void (*close)(NBDExport *),
814 Error **errp)
815 {
816 NBDExport *exp = g_malloc0(sizeof(NBDExport));
817 exp->refcount = 1;
818 QTAILQ_INIT(&exp->clients);
819 exp->blk = blk;
820 exp->dev_offset = dev_offset;
821 exp->nbdflags = nbdflags;
822 exp->size = size < 0 ? blk_getlength(blk) : size;
823 if (exp->size < 0) {
824 error_setg_errno(errp, -exp->size,
825 "Failed to determine the NBD export's length");
826 goto fail;
827 }
828 exp->size -= exp->size % BDRV_SECTOR_SIZE;
829
830 exp->close = close;
831 exp->ctx = blk_get_aio_context(blk);
832 blk_ref(blk);
833 blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
834
835 exp->eject_notifier.notify = nbd_eject_notifier;
836 blk_add_remove_bs_notifier(blk, &exp->eject_notifier);
837
838 /*
839 * NBD exports are used for non-shared storage migration. Make sure
840 * that BDRV_O_INACTIVE is cleared and the image is ready for write
841 * access since the export could be available before migration handover.
842 */
843 aio_context_acquire(exp->ctx);
844 blk_invalidate_cache(blk, NULL);
845 aio_context_release(exp->ctx);
846 return exp;
847
848 fail:
849 g_free(exp);
850 return NULL;
851 }
852
853 NBDExport *nbd_export_find(const char *name)
854 {
855 NBDExport *exp;
856 QTAILQ_FOREACH(exp, &exports, next) {
857 if (strcmp(name, exp->name) == 0) {
858 return exp;
859 }
860 }
861
862 return NULL;
863 }
864
865 void nbd_export_set_name(NBDExport *exp, const char *name)
866 {
867 if (exp->name == name) {
868 return;
869 }
870
871 nbd_export_get(exp);
872 if (exp->name != NULL) {
873 g_free(exp->name);
874 exp->name = NULL;
875 QTAILQ_REMOVE(&exports, exp, next);
876 nbd_export_put(exp);
877 }
878 if (name != NULL) {
879 nbd_export_get(exp);
880 exp->name = g_strdup(name);
881 QTAILQ_INSERT_TAIL(&exports, exp, next);
882 }
883 nbd_export_put(exp);
884 }
885
886 void nbd_export_close(NBDExport *exp)
887 {
888 NBDClient *client, *next;
889
890 nbd_export_get(exp);
891 QTAILQ_FOREACH_SAFE(client, &exp->clients, next, next) {
892 client_close(client);
893 }
894 nbd_export_set_name(exp, NULL);
895 nbd_export_put(exp);
896 }
897
898 void nbd_export_get(NBDExport *exp)
899 {
900 assert(exp->refcount > 0);
901 exp->refcount++;
902 }
903
904 void nbd_export_put(NBDExport *exp)
905 {
906 assert(exp->refcount > 0);
907 if (exp->refcount == 1) {
908 nbd_export_close(exp);
909 }
910
911 if (--exp->refcount == 0) {
912 assert(exp->name == NULL);
913
914 if (exp->close) {
915 exp->close(exp);
916 }
917
918 if (exp->blk) {
919 notifier_remove(&exp->eject_notifier);
920 blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
921 blk_aio_detach, exp);
922 blk_unref(exp->blk);
923 exp->blk = NULL;
924 }
925
926 g_free(exp);
927 }
928 }
929
930 BlockBackend *nbd_export_get_blockdev(NBDExport *exp)
931 {
932 return exp->blk;
933 }
934
935 void nbd_export_close_all(void)
936 {
937 NBDExport *exp, *next;
938
939 QTAILQ_FOREACH_SAFE(exp, &exports, next, next) {
940 nbd_export_close(exp);
941 }
942 }
943
944 static ssize_t nbd_co_send_reply(NBDRequest *req, struct nbd_reply *reply,
945 int len)
946 {
947 NBDClient *client = req->client;
948 ssize_t rc, ret;
949
950 g_assert(qemu_in_coroutine());
951 qemu_co_mutex_lock(&client->send_lock);
952 client->send_coroutine = qemu_coroutine_self();
953 nbd_set_handlers(client);
954
955 if (!len) {
956 rc = nbd_send_reply(client->ioc, reply);
957 } else {
958 qio_channel_set_cork(client->ioc, true);
959 rc = nbd_send_reply(client->ioc, reply);
960 if (rc >= 0) {
961 ret = write_sync(client->ioc, req->data, len);
962 if (ret != len) {
963 rc = -EIO;
964 }
965 }
966 qio_channel_set_cork(client->ioc, false);
967 }
968
969 client->send_coroutine = NULL;
970 nbd_set_handlers(client);
971 qemu_co_mutex_unlock(&client->send_lock);
972 return rc;
973 }
974
975 /* Collect a client request. Return 0 if request looks valid, -EAGAIN
976 * to keep trying the collection, -EIO to drop connection right away,
977 * and any other negative value to report an error to the client
978 * (although the caller may still need to disconnect after reporting
979 * the error). */
980 static ssize_t nbd_co_receive_request(NBDRequest *req,
981 struct nbd_request *request)
982 {
983 NBDClient *client = req->client;
984 uint32_t command;
985 ssize_t rc;
986
987 g_assert(qemu_in_coroutine());
988 client->recv_coroutine = qemu_coroutine_self();
989 nbd_update_can_read(client);
990
991 rc = nbd_receive_request(client->ioc, request);
992 if (rc < 0) {
993 if (rc != -EAGAIN) {
994 rc = -EIO;
995 }
996 goto out;
997 }
998
999 TRACE("Decoding type");
1000
1001 command = request->type & NBD_CMD_MASK_COMMAND;
1002 if (command != NBD_CMD_WRITE) {
1003 /* No payload, we are ready to read the next request. */
1004 req->complete = true;
1005 }
1006
1007 if (command == NBD_CMD_DISC) {
1008 /* Special case: we're going to disconnect without a reply,
1009 * whether or not flags, from, or len are bogus */
1010 TRACE("Request type is DISCONNECT");
1011 rc = -EIO;
1012 goto out;
1013 }
1014
1015 /* Check for sanity in the parameters, part 1. Defer as many
1016 * checks as possible until after reading any NBD_CMD_WRITE
1017 * payload, so we can try and keep the connection alive. */
1018 if ((request->from + request->len) < request->from) {
1019 LOG("integer overflow detected, you're probably being attacked");
1020 rc = -EINVAL;
1021 goto out;
1022 }
1023
1024 if (command == NBD_CMD_READ || command == NBD_CMD_WRITE) {
1025 if (request->len > NBD_MAX_BUFFER_SIZE) {
1026 LOG("len (%" PRIu32" ) is larger than max len (%u)",
1027 request->len, NBD_MAX_BUFFER_SIZE);
1028 rc = -EINVAL;
1029 goto out;
1030 }
1031
1032 req->data = blk_try_blockalign(client->exp->blk, request->len);
1033 if (req->data == NULL) {
1034 rc = -ENOMEM;
1035 goto out;
1036 }
1037 }
1038 if (command == NBD_CMD_WRITE) {
1039 TRACE("Reading %" PRIu32 " byte(s)", request->len);
1040
1041 if (read_sync(client->ioc, req->data, request->len) != request->len) {
1042 LOG("reading from socket failed");
1043 rc = -EIO;
1044 goto out;
1045 }
1046 req->complete = true;
1047 }
1048
1049 /* Sanity checks, part 2. */
1050 if (request->from + request->len > client->exp->size) {
1051 LOG("operation past EOF; From: %" PRIu64 ", Len: %" PRIu32
1052 ", Size: %" PRIu64, request->from, request->len,
1053 (uint64_t)client->exp->size);
1054 rc = command == NBD_CMD_WRITE ? -ENOSPC : -EINVAL;
1055 goto out;
1056 }
1057 if (request->type & ~NBD_CMD_MASK_COMMAND & ~NBD_CMD_FLAG_FUA) {
1058 LOG("unsupported flags (got 0x%x)",
1059 request->type & ~NBD_CMD_MASK_COMMAND);
1060 return -EINVAL;
1061 }
1062
1063 rc = 0;
1064
1065 out:
1066 client->recv_coroutine = NULL;
1067 nbd_update_can_read(client);
1068
1069 return rc;
1070 }
1071
1072 static void nbd_trip(void *opaque)
1073 {
1074 NBDClient *client = opaque;
1075 NBDExport *exp = client->exp;
1076 NBDRequest *req;
1077 struct nbd_request request;
1078 struct nbd_reply reply;
1079 ssize_t ret;
1080 uint32_t command;
1081 int flags;
1082
1083 TRACE("Reading request.");
1084 if (client->closing) {
1085 return;
1086 }
1087
1088 req = nbd_request_get(client);
1089 ret = nbd_co_receive_request(req, &request);
1090 if (ret == -EAGAIN) {
1091 goto done;
1092 }
1093 if (ret == -EIO) {
1094 goto out;
1095 }
1096
1097 reply.handle = request.handle;
1098 reply.error = 0;
1099
1100 if (ret < 0) {
1101 reply.error = -ret;
1102 goto error_reply;
1103 }
1104 command = request.type & NBD_CMD_MASK_COMMAND;
1105
1106 if (client->closing) {
1107 /*
1108 * The client may be closed when we are blocked in
1109 * nbd_co_receive_request()
1110 */
1111 goto done;
1112 }
1113
1114 switch (command) {
1115 case NBD_CMD_READ:
1116 TRACE("Request type is READ");
1117
1118 if (request.type & NBD_CMD_FLAG_FUA) {
1119 ret = blk_co_flush(exp->blk);
1120 if (ret < 0) {
1121 LOG("flush failed");
1122 reply.error = -ret;
1123 goto error_reply;
1124 }
1125 }
1126
1127 ret = blk_pread(exp->blk, request.from + exp->dev_offset,
1128 req->data, request.len);
1129 if (ret < 0) {
1130 LOG("reading from file failed");
1131 reply.error = -ret;
1132 goto error_reply;
1133 }
1134
1135 TRACE("Read %" PRIu32" byte(s)", request.len);
1136 if (nbd_co_send_reply(req, &reply, request.len) < 0)
1137 goto out;
1138 break;
1139 case NBD_CMD_WRITE:
1140 TRACE("Request type is WRITE");
1141
1142 if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
1143 TRACE("Server is read-only, return error");
1144 reply.error = EROFS;
1145 goto error_reply;
1146 }
1147
1148 TRACE("Writing to device");
1149
1150 flags = 0;
1151 if (request.type & NBD_CMD_FLAG_FUA) {
1152 flags |= BDRV_REQ_FUA;
1153 }
1154 ret = blk_pwrite(exp->blk, request.from + exp->dev_offset,
1155 req->data, request.len, flags);
1156 if (ret < 0) {
1157 LOG("writing to file failed");
1158 reply.error = -ret;
1159 goto error_reply;
1160 }
1161
1162 if (nbd_co_send_reply(req, &reply, 0) < 0) {
1163 goto out;
1164 }
1165 break;
1166
1167 case NBD_CMD_DISC:
1168 /* unreachable, thanks to special case in nbd_co_receive_request() */
1169 abort();
1170
1171 case NBD_CMD_FLUSH:
1172 TRACE("Request type is FLUSH");
1173
1174 ret = blk_co_flush(exp->blk);
1175 if (ret < 0) {
1176 LOG("flush failed");
1177 reply.error = -ret;
1178 }
1179 if (nbd_co_send_reply(req, &reply, 0) < 0) {
1180 goto out;
1181 }
1182 break;
1183 case NBD_CMD_TRIM:
1184 TRACE("Request type is TRIM");
1185 /* Ignore unaligned head or tail, until block layer adds byte
1186 * interface */
1187 if (request.len >= BDRV_SECTOR_SIZE) {
1188 request.len -= (request.from + request.len) % BDRV_SECTOR_SIZE;
1189 ret = blk_co_discard(exp->blk,
1190 DIV_ROUND_UP(request.from + exp->dev_offset,
1191 BDRV_SECTOR_SIZE),
1192 request.len / BDRV_SECTOR_SIZE);
1193 if (ret < 0) {
1194 LOG("discard failed");
1195 reply.error = -ret;
1196 }
1197 } else {
1198 TRACE("trim request too small, ignoring");
1199 }
1200 if (nbd_co_send_reply(req, &reply, 0) < 0) {
1201 goto out;
1202 }
1203 break;
1204 default:
1205 LOG("invalid request type (%" PRIu32 ") received", request.type);
1206 reply.error = EINVAL;
1207 error_reply:
1208 /* We must disconnect after NBD_CMD_WRITE if we did not
1209 * read the payload.
1210 */
1211 if (nbd_co_send_reply(req, &reply, 0) < 0 || !req->complete) {
1212 goto out;
1213 }
1214 break;
1215 }
1216
1217 TRACE("Request/Reply complete");
1218
1219 done:
1220 nbd_request_put(req);
1221 return;
1222
1223 out:
1224 nbd_request_put(req);
1225 client_close(client);
1226 }
1227
1228 static void nbd_read(void *opaque)
1229 {
1230 NBDClient *client = opaque;
1231
1232 if (client->recv_coroutine) {
1233 qemu_coroutine_enter(client->recv_coroutine, NULL);
1234 } else {
1235 qemu_coroutine_enter(qemu_coroutine_create(nbd_trip), client);
1236 }
1237 }
1238
1239 static void nbd_restart_write(void *opaque)
1240 {
1241 NBDClient *client = opaque;
1242
1243 qemu_coroutine_enter(client->send_coroutine, NULL);
1244 }
1245
1246 static void nbd_set_handlers(NBDClient *client)
1247 {
1248 if (client->exp && client->exp->ctx) {
1249 aio_set_fd_handler(client->exp->ctx, client->sioc->fd,
1250 true,
1251 client->can_read ? nbd_read : NULL,
1252 client->send_coroutine ? nbd_restart_write : NULL,
1253 client);
1254 }
1255 }
1256
1257 static void nbd_unset_handlers(NBDClient *client)
1258 {
1259 if (client->exp && client->exp->ctx) {
1260 aio_set_fd_handler(client->exp->ctx, client->sioc->fd,
1261 true, NULL, NULL, NULL);
1262 }
1263 }
1264
1265 static void nbd_update_can_read(NBDClient *client)
1266 {
1267 bool can_read = client->recv_coroutine ||
1268 client->nb_requests < MAX_NBD_REQUESTS;
1269
1270 if (can_read != client->can_read) {
1271 client->can_read = can_read;
1272 nbd_set_handlers(client);
1273
1274 /* There is no need to invoke aio_notify(), since aio_set_fd_handler()
1275 * in nbd_set_handlers() will have taken care of that */
1276 }
1277 }
1278
1279 static coroutine_fn void nbd_co_client_start(void *opaque)
1280 {
1281 NBDClientNewData *data = opaque;
1282 NBDClient *client = data->client;
1283 NBDExport *exp = client->exp;
1284
1285 if (exp) {
1286 nbd_export_get(exp);
1287 }
1288 if (nbd_negotiate(data)) {
1289 client_close(client);
1290 goto out;
1291 }
1292 qemu_co_mutex_init(&client->send_lock);
1293 nbd_set_handlers(client);
1294
1295 if (exp) {
1296 QTAILQ_INSERT_TAIL(&exp->clients, client, next);
1297 }
1298 out:
1299 g_free(data);
1300 }
1301
1302 void nbd_client_new(NBDExport *exp,
1303 QIOChannelSocket *sioc,
1304 QCryptoTLSCreds *tlscreds,
1305 const char *tlsaclname,
1306 void (*close_fn)(NBDClient *))
1307 {
1308 NBDClient *client;
1309 NBDClientNewData *data = g_new(NBDClientNewData, 1);
1310
1311 client = g_malloc0(sizeof(NBDClient));
1312 client->refcount = 1;
1313 client->exp = exp;
1314 client->tlscreds = tlscreds;
1315 if (tlscreds) {
1316 object_ref(OBJECT(client->tlscreds));
1317 }
1318 client->tlsaclname = g_strdup(tlsaclname);
1319 client->sioc = sioc;
1320 object_ref(OBJECT(client->sioc));
1321 client->ioc = QIO_CHANNEL(sioc);
1322 object_ref(OBJECT(client->ioc));
1323 client->can_read = true;
1324 client->close = close_fn;
1325
1326 data->client = client;
1327 data->co = qemu_coroutine_create(nbd_co_client_start);
1328 qemu_coroutine_enter(data->co, data);
1329 }