nbd: Improve server handling of bogus commands
[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[256];
290
291 /* Client sends:
292 [20 .. xx] export name (length bytes)
293 */
294 TRACE("Checking length");
295 if (length > 255) {
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 #ifdef __linux__
628
629 int nbd_disconnect(int fd)
630 {
631 ioctl(fd, NBD_CLEAR_QUE);
632 ioctl(fd, NBD_DISCONNECT);
633 ioctl(fd, NBD_CLEAR_SOCK);
634 return 0;
635 }
636
637 #else
638
639 int nbd_disconnect(int fd)
640 {
641 return -ENOTSUP;
642 }
643 #endif
644
645 static ssize_t nbd_receive_request(QIOChannel *ioc, struct nbd_request *request)
646 {
647 uint8_t buf[NBD_REQUEST_SIZE];
648 uint32_t magic;
649 ssize_t ret;
650
651 ret = read_sync(ioc, buf, sizeof(buf));
652 if (ret < 0) {
653 return ret;
654 }
655
656 if (ret != sizeof(buf)) {
657 LOG("read failed");
658 return -EINVAL;
659 }
660
661 /* Request
662 [ 0 .. 3] magic (NBD_REQUEST_MAGIC)
663 [ 4 .. 7] type (0 == READ, 1 == WRITE)
664 [ 8 .. 15] handle
665 [16 .. 23] from
666 [24 .. 27] len
667 */
668
669 magic = ldl_be_p(buf);
670 request->type = ldl_be_p(buf + 4);
671 request->handle = ldq_be_p(buf + 8);
672 request->from = ldq_be_p(buf + 16);
673 request->len = ldl_be_p(buf + 24);
674
675 TRACE("Got request: { magic = 0x%" PRIx32 ", .type = %" PRIx32
676 ", from = %" PRIu64 " , len = %" PRIu32 " }",
677 magic, request->type, request->from, request->len);
678
679 if (magic != NBD_REQUEST_MAGIC) {
680 LOG("invalid magic (got 0x%" PRIx32 ")", magic);
681 return -EINVAL;
682 }
683 return 0;
684 }
685
686 static ssize_t nbd_send_reply(QIOChannel *ioc, struct nbd_reply *reply)
687 {
688 uint8_t buf[NBD_REPLY_SIZE];
689 ssize_t ret;
690
691 reply->error = system_errno_to_nbd_errno(reply->error);
692
693 TRACE("Sending response to client: { .error = %" PRId32
694 ", handle = %" PRIu64 " }",
695 reply->error, reply->handle);
696
697 /* Reply
698 [ 0 .. 3] magic (NBD_REPLY_MAGIC)
699 [ 4 .. 7] error (0 == no error)
700 [ 7 .. 15] handle
701 */
702 stl_be_p(buf, NBD_REPLY_MAGIC);
703 stl_be_p(buf + 4, reply->error);
704 stq_be_p(buf + 8, reply->handle);
705
706 ret = write_sync(ioc, buf, sizeof(buf));
707 if (ret < 0) {
708 return ret;
709 }
710
711 if (ret != sizeof(buf)) {
712 LOG("writing to socket failed");
713 return -EINVAL;
714 }
715 return 0;
716 }
717
718 #define MAX_NBD_REQUESTS 16
719
720 void nbd_client_get(NBDClient *client)
721 {
722 client->refcount++;
723 }
724
725 void nbd_client_put(NBDClient *client)
726 {
727 if (--client->refcount == 0) {
728 /* The last reference should be dropped by client->close,
729 * which is called by client_close.
730 */
731 assert(client->closing);
732
733 nbd_unset_handlers(client);
734 object_unref(OBJECT(client->sioc));
735 object_unref(OBJECT(client->ioc));
736 if (client->tlscreds) {
737 object_unref(OBJECT(client->tlscreds));
738 }
739 g_free(client->tlsaclname);
740 if (client->exp) {
741 QTAILQ_REMOVE(&client->exp->clients, client, next);
742 nbd_export_put(client->exp);
743 }
744 g_free(client);
745 }
746 }
747
748 static void client_close(NBDClient *client)
749 {
750 if (client->closing) {
751 return;
752 }
753
754 client->closing = true;
755
756 /* Force requests to finish. They will drop their own references,
757 * then we'll close the socket and free the NBDClient.
758 */
759 qio_channel_shutdown(client->ioc, QIO_CHANNEL_SHUTDOWN_BOTH,
760 NULL);
761
762 /* Also tell the client, so that they release their reference. */
763 if (client->close) {
764 client->close(client);
765 }
766 }
767
768 static NBDRequest *nbd_request_get(NBDClient *client)
769 {
770 NBDRequest *req;
771
772 assert(client->nb_requests <= MAX_NBD_REQUESTS - 1);
773 client->nb_requests++;
774 nbd_update_can_read(client);
775
776 req = g_new0(NBDRequest, 1);
777 nbd_client_get(client);
778 req->client = client;
779 return req;
780 }
781
782 static void nbd_request_put(NBDRequest *req)
783 {
784 NBDClient *client = req->client;
785
786 if (req->data) {
787 qemu_vfree(req->data);
788 }
789 g_free(req);
790
791 client->nb_requests--;
792 nbd_update_can_read(client);
793 nbd_client_put(client);
794 }
795
796 static void blk_aio_attached(AioContext *ctx, void *opaque)
797 {
798 NBDExport *exp = opaque;
799 NBDClient *client;
800
801 TRACE("Export %s: Attaching clients to AIO context %p\n", exp->name, ctx);
802
803 exp->ctx = ctx;
804
805 QTAILQ_FOREACH(client, &exp->clients, next) {
806 nbd_set_handlers(client);
807 }
808 }
809
810 static void blk_aio_detach(void *opaque)
811 {
812 NBDExport *exp = opaque;
813 NBDClient *client;
814
815 TRACE("Export %s: Detaching clients from AIO context %p\n", exp->name, exp->ctx);
816
817 QTAILQ_FOREACH(client, &exp->clients, next) {
818 nbd_unset_handlers(client);
819 }
820
821 exp->ctx = NULL;
822 }
823
824 static void nbd_eject_notifier(Notifier *n, void *data)
825 {
826 NBDExport *exp = container_of(n, NBDExport, eject_notifier);
827 nbd_export_close(exp);
828 }
829
830 NBDExport *nbd_export_new(BlockBackend *blk, off_t dev_offset, off_t size,
831 uint32_t nbdflags, void (*close)(NBDExport *),
832 Error **errp)
833 {
834 NBDExport *exp = g_malloc0(sizeof(NBDExport));
835 exp->refcount = 1;
836 QTAILQ_INIT(&exp->clients);
837 exp->blk = blk;
838 exp->dev_offset = dev_offset;
839 exp->nbdflags = nbdflags;
840 exp->size = size < 0 ? blk_getlength(blk) : size;
841 if (exp->size < 0) {
842 error_setg_errno(errp, -exp->size,
843 "Failed to determine the NBD export's length");
844 goto fail;
845 }
846 exp->size -= exp->size % BDRV_SECTOR_SIZE;
847
848 exp->close = close;
849 exp->ctx = blk_get_aio_context(blk);
850 blk_ref(blk);
851 blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
852
853 exp->eject_notifier.notify = nbd_eject_notifier;
854 blk_add_remove_bs_notifier(blk, &exp->eject_notifier);
855
856 /*
857 * NBD exports are used for non-shared storage migration. Make sure
858 * that BDRV_O_INACTIVE is cleared and the image is ready for write
859 * access since the export could be available before migration handover.
860 */
861 aio_context_acquire(exp->ctx);
862 blk_invalidate_cache(blk, NULL);
863 aio_context_release(exp->ctx);
864 return exp;
865
866 fail:
867 g_free(exp);
868 return NULL;
869 }
870
871 NBDExport *nbd_export_find(const char *name)
872 {
873 NBDExport *exp;
874 QTAILQ_FOREACH(exp, &exports, next) {
875 if (strcmp(name, exp->name) == 0) {
876 return exp;
877 }
878 }
879
880 return NULL;
881 }
882
883 void nbd_export_set_name(NBDExport *exp, const char *name)
884 {
885 if (exp->name == name) {
886 return;
887 }
888
889 nbd_export_get(exp);
890 if (exp->name != NULL) {
891 g_free(exp->name);
892 exp->name = NULL;
893 QTAILQ_REMOVE(&exports, exp, next);
894 nbd_export_put(exp);
895 }
896 if (name != NULL) {
897 nbd_export_get(exp);
898 exp->name = g_strdup(name);
899 QTAILQ_INSERT_TAIL(&exports, exp, next);
900 }
901 nbd_export_put(exp);
902 }
903
904 void nbd_export_close(NBDExport *exp)
905 {
906 NBDClient *client, *next;
907
908 nbd_export_get(exp);
909 QTAILQ_FOREACH_SAFE(client, &exp->clients, next, next) {
910 client_close(client);
911 }
912 nbd_export_set_name(exp, NULL);
913 nbd_export_put(exp);
914 }
915
916 void nbd_export_get(NBDExport *exp)
917 {
918 assert(exp->refcount > 0);
919 exp->refcount++;
920 }
921
922 void nbd_export_put(NBDExport *exp)
923 {
924 assert(exp->refcount > 0);
925 if (exp->refcount == 1) {
926 nbd_export_close(exp);
927 }
928
929 if (--exp->refcount == 0) {
930 assert(exp->name == NULL);
931
932 if (exp->close) {
933 exp->close(exp);
934 }
935
936 if (exp->blk) {
937 notifier_remove(&exp->eject_notifier);
938 blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
939 blk_aio_detach, exp);
940 blk_unref(exp->blk);
941 exp->blk = NULL;
942 }
943
944 g_free(exp);
945 }
946 }
947
948 BlockBackend *nbd_export_get_blockdev(NBDExport *exp)
949 {
950 return exp->blk;
951 }
952
953 void nbd_export_close_all(void)
954 {
955 NBDExport *exp, *next;
956
957 QTAILQ_FOREACH_SAFE(exp, &exports, next, next) {
958 nbd_export_close(exp);
959 }
960 }
961
962 static ssize_t nbd_co_send_reply(NBDRequest *req, struct nbd_reply *reply,
963 int len)
964 {
965 NBDClient *client = req->client;
966 ssize_t rc, ret;
967
968 g_assert(qemu_in_coroutine());
969 qemu_co_mutex_lock(&client->send_lock);
970 client->send_coroutine = qemu_coroutine_self();
971 nbd_set_handlers(client);
972
973 if (!len) {
974 rc = nbd_send_reply(client->ioc, reply);
975 } else {
976 qio_channel_set_cork(client->ioc, true);
977 rc = nbd_send_reply(client->ioc, reply);
978 if (rc >= 0) {
979 ret = write_sync(client->ioc, req->data, len);
980 if (ret != len) {
981 rc = -EIO;
982 }
983 }
984 qio_channel_set_cork(client->ioc, false);
985 }
986
987 client->send_coroutine = NULL;
988 nbd_set_handlers(client);
989 qemu_co_mutex_unlock(&client->send_lock);
990 return rc;
991 }
992
993 /* Collect a client request. Return 0 if request looks valid, -EAGAIN
994 * to keep trying the collection, -EIO to drop connection right away,
995 * and any other negative value to report an error to the client
996 * (although the caller may still need to disconnect after reporting
997 * the error). */
998 static ssize_t nbd_co_receive_request(NBDRequest *req,
999 struct nbd_request *request)
1000 {
1001 NBDClient *client = req->client;
1002 uint32_t command;
1003 ssize_t rc;
1004
1005 g_assert(qemu_in_coroutine());
1006 client->recv_coroutine = qemu_coroutine_self();
1007 nbd_update_can_read(client);
1008
1009 rc = nbd_receive_request(client->ioc, request);
1010 if (rc < 0) {
1011 if (rc != -EAGAIN) {
1012 rc = -EIO;
1013 }
1014 goto out;
1015 }
1016
1017 TRACE("Decoding type");
1018
1019 command = request->type & NBD_CMD_MASK_COMMAND;
1020 if (command != NBD_CMD_WRITE) {
1021 /* No payload, we are ready to read the next request. */
1022 req->complete = true;
1023 }
1024
1025 if (command == NBD_CMD_DISC) {
1026 /* Special case: we're going to disconnect without a reply,
1027 * whether or not flags, from, or len are bogus */
1028 TRACE("Request type is DISCONNECT");
1029 rc = -EIO;
1030 goto out;
1031 }
1032
1033 /* Check for sanity in the parameters, part 1. Defer as many
1034 * checks as possible until after reading any NBD_CMD_WRITE
1035 * payload, so we can try and keep the connection alive. */
1036 if ((request->from + request->len) < request->from) {
1037 LOG("integer overflow detected, you're probably being attacked");
1038 rc = -EINVAL;
1039 goto out;
1040 }
1041
1042 if (command == NBD_CMD_READ || command == NBD_CMD_WRITE) {
1043 if (request->len > NBD_MAX_BUFFER_SIZE) {
1044 LOG("len (%" PRIu32" ) is larger than max len (%u)",
1045 request->len, NBD_MAX_BUFFER_SIZE);
1046 rc = -EINVAL;
1047 goto out;
1048 }
1049
1050 req->data = blk_try_blockalign(client->exp->blk, request->len);
1051 if (req->data == NULL) {
1052 rc = -ENOMEM;
1053 goto out;
1054 }
1055 }
1056 if (command == NBD_CMD_WRITE) {
1057 TRACE("Reading %" PRIu32 " byte(s)", request->len);
1058
1059 if (read_sync(client->ioc, req->data, request->len) != request->len) {
1060 LOG("reading from socket failed");
1061 rc = -EIO;
1062 goto out;
1063 }
1064 req->complete = true;
1065 }
1066
1067 /* Sanity checks, part 2. */
1068 if (request->from + request->len > client->exp->size) {
1069 LOG("operation past EOF; From: %" PRIu64 ", Len: %" PRIu32
1070 ", Size: %" PRIu64, request->from, request->len,
1071 (uint64_t)client->exp->size);
1072 rc = command == NBD_CMD_WRITE ? -ENOSPC : -EINVAL;
1073 goto out;
1074 }
1075
1076 rc = 0;
1077
1078 out:
1079 client->recv_coroutine = NULL;
1080 nbd_update_can_read(client);
1081
1082 return rc;
1083 }
1084
1085 static void nbd_trip(void *opaque)
1086 {
1087 NBDClient *client = opaque;
1088 NBDExport *exp = client->exp;
1089 NBDRequest *req;
1090 struct nbd_request request;
1091 struct nbd_reply reply;
1092 ssize_t ret;
1093 uint32_t command;
1094 int flags;
1095
1096 TRACE("Reading request.");
1097 if (client->closing) {
1098 return;
1099 }
1100
1101 req = nbd_request_get(client);
1102 ret = nbd_co_receive_request(req, &request);
1103 if (ret == -EAGAIN) {
1104 goto done;
1105 }
1106 if (ret == -EIO) {
1107 goto out;
1108 }
1109
1110 reply.handle = request.handle;
1111 reply.error = 0;
1112
1113 if (ret < 0) {
1114 reply.error = -ret;
1115 goto error_reply;
1116 }
1117 command = request.type & NBD_CMD_MASK_COMMAND;
1118
1119 if (client->closing) {
1120 /*
1121 * The client may be closed when we are blocked in
1122 * nbd_co_receive_request()
1123 */
1124 goto done;
1125 }
1126
1127 switch (command) {
1128 case NBD_CMD_READ:
1129 TRACE("Request type is READ");
1130
1131 if (request.type & NBD_CMD_FLAG_FUA) {
1132 ret = blk_co_flush(exp->blk);
1133 if (ret < 0) {
1134 LOG("flush failed");
1135 reply.error = -ret;
1136 goto error_reply;
1137 }
1138 }
1139
1140 ret = blk_pread(exp->blk, request.from + exp->dev_offset,
1141 req->data, request.len);
1142 if (ret < 0) {
1143 LOG("reading from file failed");
1144 reply.error = -ret;
1145 goto error_reply;
1146 }
1147
1148 TRACE("Read %" PRIu32" byte(s)", request.len);
1149 if (nbd_co_send_reply(req, &reply, request.len) < 0)
1150 goto out;
1151 break;
1152 case NBD_CMD_WRITE:
1153 TRACE("Request type is WRITE");
1154
1155 if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
1156 TRACE("Server is read-only, return error");
1157 reply.error = EROFS;
1158 goto error_reply;
1159 }
1160
1161 TRACE("Writing to device");
1162
1163 flags = 0;
1164 if (request.type & NBD_CMD_FLAG_FUA) {
1165 flags |= BDRV_REQ_FUA;
1166 }
1167 ret = blk_pwrite(exp->blk, request.from + exp->dev_offset,
1168 req->data, request.len, flags);
1169 if (ret < 0) {
1170 LOG("writing to file failed");
1171 reply.error = -ret;
1172 goto error_reply;
1173 }
1174
1175 if (nbd_co_send_reply(req, &reply, 0) < 0) {
1176 goto out;
1177 }
1178 break;
1179
1180 case NBD_CMD_DISC:
1181 /* unreachable, thanks to special case in nbd_co_receive_request() */
1182 abort();
1183
1184 case NBD_CMD_FLUSH:
1185 TRACE("Request type is FLUSH");
1186
1187 ret = blk_co_flush(exp->blk);
1188 if (ret < 0) {
1189 LOG("flush failed");
1190 reply.error = -ret;
1191 }
1192 if (nbd_co_send_reply(req, &reply, 0) < 0) {
1193 goto out;
1194 }
1195 break;
1196 case NBD_CMD_TRIM:
1197 TRACE("Request type is TRIM");
1198 /* Ignore unaligned head or tail, until block layer adds byte
1199 * interface */
1200 if (request.len >= BDRV_SECTOR_SIZE) {
1201 request.len -= (request.from + request.len) % BDRV_SECTOR_SIZE;
1202 ret = blk_co_discard(exp->blk,
1203 DIV_ROUND_UP(request.from + exp->dev_offset,
1204 BDRV_SECTOR_SIZE),
1205 request.len / BDRV_SECTOR_SIZE);
1206 if (ret < 0) {
1207 LOG("discard failed");
1208 reply.error = -ret;
1209 }
1210 } else {
1211 TRACE("trim request too small, ignoring");
1212 }
1213 if (nbd_co_send_reply(req, &reply, 0) < 0) {
1214 goto out;
1215 }
1216 break;
1217 default:
1218 LOG("invalid request type (%" PRIu32 ") received", request.type);
1219 reply.error = EINVAL;
1220 error_reply:
1221 /* We must disconnect after NBD_CMD_WRITE if we did not
1222 * read the payload.
1223 */
1224 if (nbd_co_send_reply(req, &reply, 0) < 0 || !req->complete) {
1225 goto out;
1226 }
1227 break;
1228 }
1229
1230 TRACE("Request/Reply complete");
1231
1232 done:
1233 nbd_request_put(req);
1234 return;
1235
1236 out:
1237 nbd_request_put(req);
1238 client_close(client);
1239 }
1240
1241 static void nbd_read(void *opaque)
1242 {
1243 NBDClient *client = opaque;
1244
1245 if (client->recv_coroutine) {
1246 qemu_coroutine_enter(client->recv_coroutine, NULL);
1247 } else {
1248 qemu_coroutine_enter(qemu_coroutine_create(nbd_trip), client);
1249 }
1250 }
1251
1252 static void nbd_restart_write(void *opaque)
1253 {
1254 NBDClient *client = opaque;
1255
1256 qemu_coroutine_enter(client->send_coroutine, NULL);
1257 }
1258
1259 static void nbd_set_handlers(NBDClient *client)
1260 {
1261 if (client->exp && client->exp->ctx) {
1262 aio_set_fd_handler(client->exp->ctx, client->sioc->fd,
1263 true,
1264 client->can_read ? nbd_read : NULL,
1265 client->send_coroutine ? nbd_restart_write : NULL,
1266 client);
1267 }
1268 }
1269
1270 static void nbd_unset_handlers(NBDClient *client)
1271 {
1272 if (client->exp && client->exp->ctx) {
1273 aio_set_fd_handler(client->exp->ctx, client->sioc->fd,
1274 true, NULL, NULL, NULL);
1275 }
1276 }
1277
1278 static void nbd_update_can_read(NBDClient *client)
1279 {
1280 bool can_read = client->recv_coroutine ||
1281 client->nb_requests < MAX_NBD_REQUESTS;
1282
1283 if (can_read != client->can_read) {
1284 client->can_read = can_read;
1285 nbd_set_handlers(client);
1286
1287 /* There is no need to invoke aio_notify(), since aio_set_fd_handler()
1288 * in nbd_set_handlers() will have taken care of that */
1289 }
1290 }
1291
1292 static coroutine_fn void nbd_co_client_start(void *opaque)
1293 {
1294 NBDClientNewData *data = opaque;
1295 NBDClient *client = data->client;
1296 NBDExport *exp = client->exp;
1297
1298 if (exp) {
1299 nbd_export_get(exp);
1300 }
1301 if (nbd_negotiate(data)) {
1302 client_close(client);
1303 goto out;
1304 }
1305 qemu_co_mutex_init(&client->send_lock);
1306 nbd_set_handlers(client);
1307
1308 if (exp) {
1309 QTAILQ_INSERT_TAIL(&exp->clients, client, next);
1310 }
1311 out:
1312 g_free(data);
1313 }
1314
1315 void nbd_client_new(NBDExport *exp,
1316 QIOChannelSocket *sioc,
1317 QCryptoTLSCreds *tlscreds,
1318 const char *tlsaclname,
1319 void (*close_fn)(NBDClient *))
1320 {
1321 NBDClient *client;
1322 NBDClientNewData *data = g_new(NBDClientNewData, 1);
1323
1324 client = g_malloc0(sizeof(NBDClient));
1325 client->refcount = 1;
1326 client->exp = exp;
1327 client->tlscreds = tlscreds;
1328 if (tlscreds) {
1329 object_ref(OBJECT(client->tlscreds));
1330 }
1331 client->tlsaclname = g_strdup(tlsaclname);
1332 client->sioc = sioc;
1333 object_ref(OBJECT(client->sioc));
1334 client->ioc = QIO_CHANNEL(sioc);
1335 object_ref(OBJECT(client->ioc));
1336 client->can_read = true;
1337 client->close = close_fn;
1338
1339 data->client = client;
1340 data->co = qemu_coroutine_create(nbd_co_client_start);
1341 qemu_coroutine_enter(data->co, data);
1342 }