xref: /openbmc/qemu/nbd/server.c (revision 80adf54e)
1 /*
2  *  Copyright (C) 2016-2017 Red Hat, Inc.
3  *  Copyright (C) 2005  Anthony Liguori <anthony@codemonkey.ws>
4  *
5  *  Network Block Device Server 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 static int system_errno_to_nbd_errno(int err)
26 {
27     switch (err) {
28     case 0:
29         return NBD_SUCCESS;
30     case EPERM:
31     case EROFS:
32         return NBD_EPERM;
33     case EIO:
34         return NBD_EIO;
35     case ENOMEM:
36         return NBD_ENOMEM;
37 #ifdef EDQUOT
38     case EDQUOT:
39 #endif
40     case EFBIG:
41     case ENOSPC:
42         return NBD_ENOSPC;
43     case ESHUTDOWN:
44         return NBD_ESHUTDOWN;
45     case EINVAL:
46     default:
47         return NBD_EINVAL;
48     }
49 }
50 
51 /* Definitions for opaque data types */
52 
53 typedef struct NBDRequestData NBDRequestData;
54 
55 struct NBDRequestData {
56     QSIMPLEQ_ENTRY(NBDRequestData) entry;
57     NBDClient *client;
58     uint8_t *data;
59     bool complete;
60 };
61 
62 struct NBDExport {
63     int refcount;
64     void (*close)(NBDExport *exp);
65 
66     BlockBackend *blk;
67     char *name;
68     char *description;
69     off_t dev_offset;
70     off_t size;
71     uint16_t nbdflags;
72     QTAILQ_HEAD(, NBDClient) clients;
73     QTAILQ_ENTRY(NBDExport) next;
74 
75     AioContext *ctx;
76 
77     BlockBackend *eject_notifier_blk;
78     Notifier eject_notifier;
79 };
80 
81 static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
82 
83 struct NBDClient {
84     int refcount;
85     void (*close_fn)(NBDClient *client, bool negotiated);
86 
87     NBDExport *exp;
88     QCryptoTLSCreds *tlscreds;
89     char *tlsaclname;
90     QIOChannelSocket *sioc; /* The underlying data channel */
91     QIOChannel *ioc; /* The current I/O channel which may differ (eg TLS) */
92 
93     Coroutine *recv_coroutine;
94 
95     CoMutex send_lock;
96     Coroutine *send_coroutine;
97 
98     QTAILQ_ENTRY(NBDClient) next;
99     int nb_requests;
100     bool closing;
101 };
102 
103 /* That's all folks */
104 
105 static void nbd_client_receive_next_request(NBDClient *client);
106 
107 /* Basic flow for negotiation
108 
109    Server         Client
110    Negotiate
111 
112    or
113 
114    Server         Client
115    Negotiate #1
116                   Option
117    Negotiate #2
118 
119    ----
120 
121    followed by
122 
123    Server         Client
124                   Request
125    Response
126                   Request
127    Response
128                   ...
129    ...
130                   Request (type == 2)
131 
132 */
133 
134 /* Send a reply header, including length, but no payload.
135  * Return -errno on error, 0 on success. */
136 static int nbd_negotiate_send_rep_len(QIOChannel *ioc, uint32_t type,
137                                       uint32_t opt, uint32_t len, Error **errp)
138 {
139     uint64_t magic;
140 
141     trace_nbd_negotiate_send_rep_len(opt, nbd_opt_lookup(opt),
142                                      type, nbd_rep_lookup(type), len);
143 
144     assert(len < NBD_MAX_BUFFER_SIZE);
145     magic = cpu_to_be64(NBD_REP_MAGIC);
146     if (nbd_write(ioc, &magic, sizeof(magic), errp) < 0) {
147         error_prepend(errp, "write failed (rep magic): ");
148         return -EINVAL;
149     }
150 
151     opt = cpu_to_be32(opt);
152     if (nbd_write(ioc, &opt, sizeof(opt), errp) < 0) {
153         error_prepend(errp, "write failed (rep opt): ");
154         return -EINVAL;
155     }
156 
157     type = cpu_to_be32(type);
158     if (nbd_write(ioc, &type, sizeof(type), errp) < 0) {
159         error_prepend(errp, "write failed (rep type): ");
160         return -EINVAL;
161     }
162 
163     len = cpu_to_be32(len);
164     if (nbd_write(ioc, &len, sizeof(len), errp) < 0) {
165         error_prepend(errp, "write failed (rep data length): ");
166         return -EINVAL;
167     }
168     return 0;
169 }
170 
171 /* Send a reply header with default 0 length.
172  * Return -errno on error, 0 on success. */
173 static int nbd_negotiate_send_rep(QIOChannel *ioc, uint32_t type, uint32_t opt,
174                                   Error **errp)
175 {
176     return nbd_negotiate_send_rep_len(ioc, type, opt, 0, errp);
177 }
178 
179 /* Send an error reply.
180  * Return -errno on error, 0 on success. */
181 static int GCC_FMT_ATTR(5, 6)
182 nbd_negotiate_send_rep_err(QIOChannel *ioc, uint32_t type,
183                            uint32_t opt, Error **errp, const char *fmt, ...)
184 {
185     va_list va;
186     char *msg;
187     int ret;
188     size_t len;
189 
190     va_start(va, fmt);
191     msg = g_strdup_vprintf(fmt, va);
192     va_end(va);
193     len = strlen(msg);
194     assert(len < 4096);
195     trace_nbd_negotiate_send_rep_err(msg);
196     ret = nbd_negotiate_send_rep_len(ioc, type, opt, len, errp);
197     if (ret < 0) {
198         goto out;
199     }
200     if (nbd_write(ioc, msg, len, errp) < 0) {
201         error_prepend(errp, "write failed (error message): ");
202         ret = -EIO;
203     } else {
204         ret = 0;
205     }
206 
207 out:
208     g_free(msg);
209     return ret;
210 }
211 
212 /* Send a single NBD_REP_SERVER reply to NBD_OPT_LIST, including payload.
213  * Return -errno on error, 0 on success. */
214 static int nbd_negotiate_send_rep_list(QIOChannel *ioc, NBDExport *exp,
215                                        Error **errp)
216 {
217     size_t name_len, desc_len;
218     uint32_t len;
219     const char *name = exp->name ? exp->name : "";
220     const char *desc = exp->description ? exp->description : "";
221     int ret;
222 
223     trace_nbd_negotiate_send_rep_list(name, desc);
224     name_len = strlen(name);
225     desc_len = strlen(desc);
226     len = name_len + desc_len + sizeof(len);
227     ret = nbd_negotiate_send_rep_len(ioc, NBD_REP_SERVER, NBD_OPT_LIST, len,
228                                      errp);
229     if (ret < 0) {
230         return ret;
231     }
232 
233     len = cpu_to_be32(name_len);
234     if (nbd_write(ioc, &len, sizeof(len), errp) < 0) {
235         error_prepend(errp, "write failed (name length): ");
236         return -EINVAL;
237     }
238 
239     if (nbd_write(ioc, name, name_len, errp) < 0) {
240         error_prepend(errp, "write failed (name buffer): ");
241         return -EINVAL;
242     }
243 
244     if (nbd_write(ioc, desc, desc_len, errp) < 0) {
245         error_prepend(errp, "write failed (description buffer): ");
246         return -EINVAL;
247     }
248 
249     return 0;
250 }
251 
252 /* Process the NBD_OPT_LIST command, with a potential series of replies.
253  * Return -errno on error, 0 on success. */
254 static int nbd_negotiate_handle_list(NBDClient *client, uint32_t length,
255                                      Error **errp)
256 {
257     NBDExport *exp;
258 
259     if (length) {
260         if (nbd_drop(client->ioc, length, errp) < 0) {
261             return -EIO;
262         }
263         return nbd_negotiate_send_rep_err(client->ioc,
264                                           NBD_REP_ERR_INVALID, NBD_OPT_LIST,
265                                           errp,
266                                           "OPT_LIST should not have length");
267     }
268 
269     /* For each export, send a NBD_REP_SERVER reply. */
270     QTAILQ_FOREACH(exp, &exports, next) {
271         if (nbd_negotiate_send_rep_list(client->ioc, exp, errp)) {
272             return -EINVAL;
273         }
274     }
275     /* Finish with a NBD_REP_ACK. */
276     return nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, NBD_OPT_LIST, errp);
277 }
278 
279 /* Send a reply to NBD_OPT_EXPORT_NAME.
280  * Return -errno on error, 0 on success. */
281 static int nbd_negotiate_handle_export_name(NBDClient *client, uint32_t length,
282                                             uint16_t myflags, bool no_zeroes,
283                                             Error **errp)
284 {
285     char name[NBD_MAX_NAME_SIZE + 1];
286     char buf[NBD_REPLY_EXPORT_NAME_SIZE] = "";
287     size_t len;
288     int ret;
289 
290     /* Client sends:
291         [20 ..  xx]   export name (length bytes)
292        Server replies:
293         [ 0 ..   7]   size
294         [ 8 ..   9]   export flags
295         [10 .. 133]   reserved     (0) [unless no_zeroes]
296      */
297     trace_nbd_negotiate_handle_export_name();
298     if (length >= sizeof(name)) {
299         error_setg(errp, "Bad length received");
300         return -EINVAL;
301     }
302     if (nbd_read(client->ioc, name, length, errp) < 0) {
303         error_prepend(errp, "read failed: ");
304         return -EINVAL;
305     }
306     name[length] = '\0';
307 
308     trace_nbd_negotiate_handle_export_name_request(name);
309 
310     client->exp = nbd_export_find(name);
311     if (!client->exp) {
312         error_setg(errp, "export not found");
313         return -EINVAL;
314     }
315 
316     trace_nbd_negotiate_new_style_size_flags(client->exp->size,
317                                              client->exp->nbdflags | myflags);
318     stq_be_p(buf, client->exp->size);
319     stw_be_p(buf + 8, client->exp->nbdflags | myflags);
320     len = no_zeroes ? 10 : sizeof(buf);
321     ret = nbd_write(client->ioc, buf, len, errp);
322     if (ret < 0) {
323         error_prepend(errp, "write failed: ");
324         return ret;
325     }
326 
327     QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
328     nbd_export_get(client->exp);
329 
330     return 0;
331 }
332 
333 /* Send a single NBD_REP_INFO, with a buffer @buf of @length bytes.
334  * The buffer does NOT include the info type prefix.
335  * Return -errno on error, 0 if ready to send more. */
336 static int nbd_negotiate_send_info(NBDClient *client, uint32_t opt,
337                                    uint16_t info, uint32_t length, void *buf,
338                                    Error **errp)
339 {
340     int rc;
341 
342     trace_nbd_negotiate_send_info(info, nbd_info_lookup(info), length);
343     rc = nbd_negotiate_send_rep_len(client->ioc, NBD_REP_INFO, opt,
344                                     sizeof(info) + length, errp);
345     if (rc < 0) {
346         return rc;
347     }
348     cpu_to_be16s(&info);
349     if (nbd_write(client->ioc, &info, sizeof(info), errp) < 0) {
350         return -EIO;
351     }
352     if (nbd_write(client->ioc, buf, length, errp) < 0) {
353         return -EIO;
354     }
355     return 0;
356 }
357 
358 /* Handle NBD_OPT_INFO and NBD_OPT_GO.
359  * Return -errno on error, 0 if ready for next option, and 1 to move
360  * into transmission phase.  */
361 static int nbd_negotiate_handle_info(NBDClient *client, uint32_t length,
362                                      uint32_t opt, uint16_t myflags,
363                                      Error **errp)
364 {
365     int rc;
366     char name[NBD_MAX_NAME_SIZE + 1];
367     NBDExport *exp;
368     uint16_t requests;
369     uint16_t request;
370     uint32_t namelen;
371     bool sendname = false;
372     bool blocksize = false;
373     uint32_t sizes[3];
374     char buf[sizeof(uint64_t) + sizeof(uint16_t)];
375     const char *msg;
376 
377     /* Client sends:
378         4 bytes: L, name length (can be 0)
379         L bytes: export name
380         2 bytes: N, number of requests (can be 0)
381         N * 2 bytes: N requests
382     */
383     if (length < sizeof(namelen) + sizeof(requests)) {
384         msg = "overall request too short";
385         goto invalid;
386     }
387     if (nbd_read(client->ioc, &namelen, sizeof(namelen), errp) < 0) {
388         return -EIO;
389     }
390     be32_to_cpus(&namelen);
391     length -= sizeof(namelen);
392     if (namelen > length - sizeof(requests) || (length - namelen) % 2) {
393         msg = "name length is incorrect";
394         goto invalid;
395     }
396     if (nbd_read(client->ioc, name, namelen, errp) < 0) {
397         return -EIO;
398     }
399     name[namelen] = '\0';
400     length -= namelen;
401     trace_nbd_negotiate_handle_export_name_request(name);
402 
403     if (nbd_read(client->ioc, &requests, sizeof(requests), errp) < 0) {
404         return -EIO;
405     }
406     be16_to_cpus(&requests);
407     length -= sizeof(requests);
408     trace_nbd_negotiate_handle_info_requests(requests);
409     if (requests != length / sizeof(request)) {
410         msg = "incorrect number of  requests for overall length";
411         goto invalid;
412     }
413     while (requests--) {
414         if (nbd_read(client->ioc, &request, sizeof(request), errp) < 0) {
415             return -EIO;
416         }
417         be16_to_cpus(&request);
418         length -= sizeof(request);
419         trace_nbd_negotiate_handle_info_request(request,
420                                                 nbd_info_lookup(request));
421         /* We care about NBD_INFO_NAME and NBD_INFO_BLOCK_SIZE;
422          * everything else is either a request we don't know or
423          * something we send regardless of request */
424         switch (request) {
425         case NBD_INFO_NAME:
426             sendname = true;
427             break;
428         case NBD_INFO_BLOCK_SIZE:
429             blocksize = true;
430             break;
431         }
432     }
433 
434     exp = nbd_export_find(name);
435     if (!exp) {
436         return nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_UNKNOWN,
437                                           opt, errp, "export '%s' not present",
438                                           name);
439     }
440 
441     /* Don't bother sending NBD_INFO_NAME unless client requested it */
442     if (sendname) {
443         rc = nbd_negotiate_send_info(client, opt, NBD_INFO_NAME, length, name,
444                                      errp);
445         if (rc < 0) {
446             return rc;
447         }
448     }
449 
450     /* Send NBD_INFO_DESCRIPTION only if available, regardless of
451      * client request */
452     if (exp->description) {
453         size_t len = strlen(exp->description);
454 
455         rc = nbd_negotiate_send_info(client, opt, NBD_INFO_DESCRIPTION,
456                                      len, exp->description, errp);
457         if (rc < 0) {
458             return rc;
459         }
460     }
461 
462     /* Send NBD_INFO_BLOCK_SIZE always, but tweak the minimum size
463      * according to whether the client requested it, and according to
464      * whether this is OPT_INFO or OPT_GO. */
465     /* minimum - 1 for back-compat, or 512 if client is new enough.
466      * TODO: consult blk_bs(blk)->bl.request_alignment? */
467     sizes[0] = (opt == NBD_OPT_INFO || blocksize) ? BDRV_SECTOR_SIZE : 1;
468     /* preferred - Hard-code to 4096 for now.
469      * TODO: is blk_bs(blk)->bl.opt_transfer appropriate? */
470     sizes[1] = 4096;
471     /* maximum - At most 32M, but smaller as appropriate. */
472     sizes[2] = MIN(blk_get_max_transfer(exp->blk), NBD_MAX_BUFFER_SIZE);
473     trace_nbd_negotiate_handle_info_block_size(sizes[0], sizes[1], sizes[2]);
474     cpu_to_be32s(&sizes[0]);
475     cpu_to_be32s(&sizes[1]);
476     cpu_to_be32s(&sizes[2]);
477     rc = nbd_negotiate_send_info(client, opt, NBD_INFO_BLOCK_SIZE,
478                                  sizeof(sizes), sizes, errp);
479     if (rc < 0) {
480         return rc;
481     }
482 
483     /* Send NBD_INFO_EXPORT always */
484     trace_nbd_negotiate_new_style_size_flags(exp->size,
485                                              exp->nbdflags | myflags);
486     stq_be_p(buf, exp->size);
487     stw_be_p(buf + 8, exp->nbdflags | myflags);
488     rc = nbd_negotiate_send_info(client, opt, NBD_INFO_EXPORT,
489                                  sizeof(buf), buf, errp);
490     if (rc < 0) {
491         return rc;
492     }
493 
494     /* If the client is just asking for NBD_OPT_INFO, but forgot to
495      * request block sizes, return an error.
496      * TODO: consult blk_bs(blk)->request_align, and only error if it
497      * is not 1? */
498     if (opt == NBD_OPT_INFO && !blocksize) {
499         return nbd_negotiate_send_rep_err(client->ioc,
500                                           NBD_REP_ERR_BLOCK_SIZE_REQD, opt,
501                                           errp,
502                                           "request NBD_INFO_BLOCK_SIZE to "
503                                           "use this export");
504     }
505 
506     /* Final reply */
507     rc = nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, opt, errp);
508     if (rc < 0) {
509         return rc;
510     }
511 
512     if (opt == NBD_OPT_GO) {
513         client->exp = exp;
514         QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
515         nbd_export_get(client->exp);
516         rc = 1;
517     }
518     return rc;
519 
520  invalid:
521     if (nbd_drop(client->ioc, length, errp) < 0) {
522         return -EIO;
523     }
524     return nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_INVALID, opt,
525                                       errp, "%s", msg);
526 }
527 
528 
529 /* Handle NBD_OPT_STARTTLS. Return NULL to drop connection, or else the
530  * new channel for all further (now-encrypted) communication. */
531 static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client,
532                                                  uint32_t length,
533                                                  Error **errp)
534 {
535     QIOChannel *ioc;
536     QIOChannelTLS *tioc;
537     struct NBDTLSHandshakeData data = { 0 };
538 
539     trace_nbd_negotiate_handle_starttls();
540     ioc = client->ioc;
541     if (length) {
542         if (nbd_drop(ioc, length, errp) < 0) {
543             return NULL;
544         }
545         nbd_negotiate_send_rep_err(ioc, NBD_REP_ERR_INVALID, NBD_OPT_STARTTLS,
546                                    errp,
547                                    "OPT_STARTTLS should not have length");
548         return NULL;
549     }
550 
551     if (nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK,
552                                NBD_OPT_STARTTLS, errp) < 0) {
553         return NULL;
554     }
555 
556     tioc = qio_channel_tls_new_server(ioc,
557                                       client->tlscreds,
558                                       client->tlsaclname,
559                                       errp);
560     if (!tioc) {
561         return NULL;
562     }
563 
564     qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-server-tls");
565     trace_nbd_negotiate_handle_starttls_handshake();
566     data.loop = g_main_loop_new(g_main_context_default(), FALSE);
567     qio_channel_tls_handshake(tioc,
568                               nbd_tls_handshake,
569                               &data,
570                               NULL);
571 
572     if (!data.complete) {
573         g_main_loop_run(data.loop);
574     }
575     g_main_loop_unref(data.loop);
576     if (data.error) {
577         object_unref(OBJECT(tioc));
578         error_propagate(errp, data.error);
579         return NULL;
580     }
581 
582     return QIO_CHANNEL(tioc);
583 }
584 
585 /* nbd_negotiate_options
586  * Process all NBD_OPT_* client option commands, during fixed newstyle
587  * negotiation.
588  * Return:
589  * -errno  on error, errp is set
590  * 0       on successful negotiation, errp is not set
591  * 1       if client sent NBD_OPT_ABORT, i.e. on valid disconnect,
592  *         errp is not set
593  */
594 static int nbd_negotiate_options(NBDClient *client, uint16_t myflags,
595                                  Error **errp)
596 {
597     uint32_t flags;
598     bool fixedNewstyle = false;
599     bool no_zeroes = false;
600 
601     /* Client sends:
602         [ 0 ..   3]   client flags
603 
604        Then we loop until NBD_OPT_EXPORT_NAME or NBD_OPT_GO:
605         [ 0 ..   7]   NBD_OPTS_MAGIC
606         [ 8 ..  11]   NBD option
607         [12 ..  15]   Data length
608         ...           Rest of request
609 
610         [ 0 ..   7]   NBD_OPTS_MAGIC
611         [ 8 ..  11]   Second NBD option
612         [12 ..  15]   Data length
613         ...           Rest of request
614     */
615 
616     if (nbd_read(client->ioc, &flags, sizeof(flags), errp) < 0) {
617         error_prepend(errp, "read failed: ");
618         return -EIO;
619     }
620     be32_to_cpus(&flags);
621     trace_nbd_negotiate_options_flags(flags);
622     if (flags & NBD_FLAG_C_FIXED_NEWSTYLE) {
623         fixedNewstyle = true;
624         flags &= ~NBD_FLAG_C_FIXED_NEWSTYLE;
625     }
626     if (flags & NBD_FLAG_C_NO_ZEROES) {
627         no_zeroes = true;
628         flags &= ~NBD_FLAG_C_NO_ZEROES;
629     }
630     if (flags != 0) {
631         error_setg(errp, "Unknown client flags 0x%" PRIx32 " received", flags);
632         return -EINVAL;
633     }
634 
635     while (1) {
636         int ret;
637         uint32_t option, length;
638         uint64_t magic;
639 
640         if (nbd_read(client->ioc, &magic, sizeof(magic), errp) < 0) {
641             error_prepend(errp, "read failed: ");
642             return -EINVAL;
643         }
644         magic = be64_to_cpu(magic);
645         trace_nbd_negotiate_options_check_magic(magic);
646         if (magic != NBD_OPTS_MAGIC) {
647             error_setg(errp, "Bad magic received");
648             return -EINVAL;
649         }
650 
651         if (nbd_read(client->ioc, &option,
652                      sizeof(option), errp) < 0) {
653             error_prepend(errp, "read failed: ");
654             return -EINVAL;
655         }
656         option = be32_to_cpu(option);
657 
658         if (nbd_read(client->ioc, &length, sizeof(length), errp) < 0) {
659             error_prepend(errp, "read failed: ");
660             return -EINVAL;
661         }
662         length = be32_to_cpu(length);
663 
664         trace_nbd_negotiate_options_check_option(option,
665                                                  nbd_opt_lookup(option));
666         if (client->tlscreds &&
667             client->ioc == (QIOChannel *)client->sioc) {
668             QIOChannel *tioc;
669             if (!fixedNewstyle) {
670                 error_setg(errp, "Unsupported option 0x%" PRIx32, option);
671                 return -EINVAL;
672             }
673             switch (option) {
674             case NBD_OPT_STARTTLS:
675                 tioc = nbd_negotiate_handle_starttls(client, length, errp);
676                 if (!tioc) {
677                     return -EIO;
678                 }
679                 object_unref(OBJECT(client->ioc));
680                 client->ioc = QIO_CHANNEL(tioc);
681                 break;
682 
683             case NBD_OPT_EXPORT_NAME:
684                 /* No way to return an error to client, so drop connection */
685                 error_setg(errp, "Option 0x%x not permitted before TLS",
686                            option);
687                 return -EINVAL;
688 
689             default:
690                 if (nbd_drop(client->ioc, length, errp) < 0) {
691                     return -EIO;
692                 }
693                 ret = nbd_negotiate_send_rep_err(client->ioc,
694                                                  NBD_REP_ERR_TLS_REQD,
695                                                  option, errp,
696                                                  "Option 0x%" PRIx32
697                                                  "not permitted before TLS",
698                                                  option);
699                 if (ret < 0) {
700                     return ret;
701                 }
702                 /* Let the client keep trying, unless they asked to
703                  * quit. In this mode, we've already sent an error, so
704                  * we can't ack the abort.  */
705                 if (option == NBD_OPT_ABORT) {
706                     return 1;
707                 }
708                 break;
709             }
710         } else if (fixedNewstyle) {
711             switch (option) {
712             case NBD_OPT_LIST:
713                 ret = nbd_negotiate_handle_list(client, length, errp);
714                 if (ret < 0) {
715                     return ret;
716                 }
717                 break;
718 
719             case NBD_OPT_ABORT:
720                 /* NBD spec says we must try to reply before
721                  * disconnecting, but that we must also tolerate
722                  * guests that don't wait for our reply. */
723                 nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, option, NULL);
724                 return 1;
725 
726             case NBD_OPT_EXPORT_NAME:
727                 return nbd_negotiate_handle_export_name(client, length,
728                                                         myflags, no_zeroes,
729                                                         errp);
730 
731             case NBD_OPT_INFO:
732             case NBD_OPT_GO:
733                 ret = nbd_negotiate_handle_info(client, length, option,
734                                                 myflags, errp);
735                 if (ret == 1) {
736                     assert(option == NBD_OPT_GO);
737                     return 0;
738                 }
739                 if (ret) {
740                     return ret;
741                 }
742                 break;
743 
744             case NBD_OPT_STARTTLS:
745                 if (nbd_drop(client->ioc, length, errp) < 0) {
746                     return -EIO;
747                 }
748                 if (client->tlscreds) {
749                     ret = nbd_negotiate_send_rep_err(client->ioc,
750                                                      NBD_REP_ERR_INVALID,
751                                                      option, errp,
752                                                      "TLS already enabled");
753                 } else {
754                     ret = nbd_negotiate_send_rep_err(client->ioc,
755                                                      NBD_REP_ERR_POLICY,
756                                                      option, errp,
757                                                      "TLS not configured");
758                 }
759                 if (ret < 0) {
760                     return ret;
761                 }
762                 break;
763             default:
764                 if (nbd_drop(client->ioc, length, errp) < 0) {
765                     return -EIO;
766                 }
767                 ret = nbd_negotiate_send_rep_err(client->ioc,
768                                                  NBD_REP_ERR_UNSUP,
769                                                  option, errp,
770                                                  "Unsupported option 0x%"
771                                                  PRIx32 " (%s)", option,
772                                                  nbd_opt_lookup(option));
773                 if (ret < 0) {
774                     return ret;
775                 }
776                 break;
777             }
778         } else {
779             /*
780              * If broken new-style we should drop the connection
781              * for anything except NBD_OPT_EXPORT_NAME
782              */
783             switch (option) {
784             case NBD_OPT_EXPORT_NAME:
785                 return nbd_negotiate_handle_export_name(client, length,
786                                                         myflags, no_zeroes,
787                                                         errp);
788 
789             default:
790                 error_setg(errp, "Unsupported option 0x%" PRIx32 " (%s)",
791                            option, nbd_opt_lookup(option));
792                 return -EINVAL;
793             }
794         }
795     }
796 }
797 
798 /* nbd_negotiate
799  * Return:
800  * -errno  on error, errp is set
801  * 0       on successful negotiation, errp is not set
802  * 1       if client sent NBD_OPT_ABORT, i.e. on valid disconnect,
803  *         errp is not set
804  */
805 static coroutine_fn int nbd_negotiate(NBDClient *client, Error **errp)
806 {
807     char buf[NBD_OLDSTYLE_NEGOTIATE_SIZE] = "";
808     int ret;
809     const uint16_t myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM |
810                               NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA |
811                               NBD_FLAG_SEND_WRITE_ZEROES);
812     bool oldStyle;
813 
814     /* Old style negotiation header, no room for options
815         [ 0 ..   7]   passwd       ("NBDMAGIC")
816         [ 8 ..  15]   magic        (NBD_CLIENT_MAGIC)
817         [16 ..  23]   size
818         [24 ..  27]   export flags (zero-extended)
819         [28 .. 151]   reserved     (0)
820 
821        New style negotiation header, client can send options
822         [ 0 ..   7]   passwd       ("NBDMAGIC")
823         [ 8 ..  15]   magic        (NBD_OPTS_MAGIC)
824         [16 ..  17]   server flags (0)
825         ....options sent, ending in NBD_OPT_EXPORT_NAME or NBD_OPT_GO....
826      */
827 
828     qio_channel_set_blocking(client->ioc, false, NULL);
829 
830     trace_nbd_negotiate_begin();
831     memcpy(buf, "NBDMAGIC", 8);
832 
833     oldStyle = client->exp != NULL && !client->tlscreds;
834     if (oldStyle) {
835         trace_nbd_negotiate_old_style(client->exp->size,
836                                       client->exp->nbdflags | myflags);
837         stq_be_p(buf + 8, NBD_CLIENT_MAGIC);
838         stq_be_p(buf + 16, client->exp->size);
839         stl_be_p(buf + 24, client->exp->nbdflags | myflags);
840 
841         if (nbd_write(client->ioc, buf, sizeof(buf), errp) < 0) {
842             error_prepend(errp, "write failed: ");
843             return -EINVAL;
844         }
845     } else {
846         stq_be_p(buf + 8, NBD_OPTS_MAGIC);
847         stw_be_p(buf + 16, NBD_FLAG_FIXED_NEWSTYLE | NBD_FLAG_NO_ZEROES);
848 
849         if (nbd_write(client->ioc, buf, 18, errp) < 0) {
850             error_prepend(errp, "write failed: ");
851             return -EINVAL;
852         }
853         ret = nbd_negotiate_options(client, myflags, errp);
854         if (ret != 0) {
855             if (ret < 0) {
856                 error_prepend(errp, "option negotiation failed: ");
857             }
858             return ret;
859         }
860     }
861 
862     trace_nbd_negotiate_success();
863 
864     return 0;
865 }
866 
867 static int nbd_receive_request(QIOChannel *ioc, NBDRequest *request,
868                                Error **errp)
869 {
870     uint8_t buf[NBD_REQUEST_SIZE];
871     uint32_t magic;
872     int ret;
873 
874     ret = nbd_read(ioc, buf, sizeof(buf), errp);
875     if (ret < 0) {
876         return ret;
877     }
878 
879     /* Request
880        [ 0 ..  3]   magic   (NBD_REQUEST_MAGIC)
881        [ 4 ..  5]   flags   (NBD_CMD_FLAG_FUA, ...)
882        [ 6 ..  7]   type    (NBD_CMD_READ, ...)
883        [ 8 .. 15]   handle
884        [16 .. 23]   from
885        [24 .. 27]   len
886      */
887 
888     magic = ldl_be_p(buf);
889     request->flags  = lduw_be_p(buf + 4);
890     request->type   = lduw_be_p(buf + 6);
891     request->handle = ldq_be_p(buf + 8);
892     request->from   = ldq_be_p(buf + 16);
893     request->len    = ldl_be_p(buf + 24);
894 
895     trace_nbd_receive_request(magic, request->flags, request->type,
896                               request->from, request->len);
897 
898     if (magic != NBD_REQUEST_MAGIC) {
899         error_setg(errp, "invalid magic (got 0x%" PRIx32 ")", magic);
900         return -EINVAL;
901     }
902     return 0;
903 }
904 
905 static int nbd_send_reply(QIOChannel *ioc, NBDReply *reply, Error **errp)
906 {
907     uint8_t buf[NBD_REPLY_SIZE];
908 
909     reply->error = system_errno_to_nbd_errno(reply->error);
910 
911     trace_nbd_send_reply(reply->error, reply->handle);
912 
913     /* Reply
914        [ 0 ..  3]    magic   (NBD_REPLY_MAGIC)
915        [ 4 ..  7]    error   (0 == no error)
916        [ 7 .. 15]    handle
917      */
918     stl_be_p(buf, NBD_REPLY_MAGIC);
919     stl_be_p(buf + 4, reply->error);
920     stq_be_p(buf + 8, reply->handle);
921 
922     return nbd_write(ioc, buf, sizeof(buf), errp);
923 }
924 
925 #define MAX_NBD_REQUESTS 16
926 
927 void nbd_client_get(NBDClient *client)
928 {
929     client->refcount++;
930 }
931 
932 void nbd_client_put(NBDClient *client)
933 {
934     if (--client->refcount == 0) {
935         /* The last reference should be dropped by client->close,
936          * which is called by client_close.
937          */
938         assert(client->closing);
939 
940         qio_channel_detach_aio_context(client->ioc);
941         object_unref(OBJECT(client->sioc));
942         object_unref(OBJECT(client->ioc));
943         if (client->tlscreds) {
944             object_unref(OBJECT(client->tlscreds));
945         }
946         g_free(client->tlsaclname);
947         if (client->exp) {
948             QTAILQ_REMOVE(&client->exp->clients, client, next);
949             nbd_export_put(client->exp);
950         }
951         g_free(client);
952     }
953 }
954 
955 static void client_close(NBDClient *client, bool negotiated)
956 {
957     if (client->closing) {
958         return;
959     }
960 
961     client->closing = true;
962 
963     /* Force requests to finish.  They will drop their own references,
964      * then we'll close the socket and free the NBDClient.
965      */
966     qio_channel_shutdown(client->ioc, QIO_CHANNEL_SHUTDOWN_BOTH,
967                          NULL);
968 
969     /* Also tell the client, so that they release their reference.  */
970     if (client->close_fn) {
971         client->close_fn(client, negotiated);
972     }
973 }
974 
975 static NBDRequestData *nbd_request_get(NBDClient *client)
976 {
977     NBDRequestData *req;
978 
979     assert(client->nb_requests <= MAX_NBD_REQUESTS - 1);
980     client->nb_requests++;
981 
982     req = g_new0(NBDRequestData, 1);
983     nbd_client_get(client);
984     req->client = client;
985     return req;
986 }
987 
988 static void nbd_request_put(NBDRequestData *req)
989 {
990     NBDClient *client = req->client;
991 
992     if (req->data) {
993         qemu_vfree(req->data);
994     }
995     g_free(req);
996 
997     client->nb_requests--;
998     nbd_client_receive_next_request(client);
999 
1000     nbd_client_put(client);
1001 }
1002 
1003 static void blk_aio_attached(AioContext *ctx, void *opaque)
1004 {
1005     NBDExport *exp = opaque;
1006     NBDClient *client;
1007 
1008     trace_nbd_blk_aio_attached(exp->name, ctx);
1009 
1010     exp->ctx = ctx;
1011 
1012     QTAILQ_FOREACH(client, &exp->clients, next) {
1013         qio_channel_attach_aio_context(client->ioc, ctx);
1014         if (client->recv_coroutine) {
1015             aio_co_schedule(ctx, client->recv_coroutine);
1016         }
1017         if (client->send_coroutine) {
1018             aio_co_schedule(ctx, client->send_coroutine);
1019         }
1020     }
1021 }
1022 
1023 static void blk_aio_detach(void *opaque)
1024 {
1025     NBDExport *exp = opaque;
1026     NBDClient *client;
1027 
1028     trace_nbd_blk_aio_detach(exp->name, exp->ctx);
1029 
1030     QTAILQ_FOREACH(client, &exp->clients, next) {
1031         qio_channel_detach_aio_context(client->ioc);
1032     }
1033 
1034     exp->ctx = NULL;
1035 }
1036 
1037 static void nbd_eject_notifier(Notifier *n, void *data)
1038 {
1039     NBDExport *exp = container_of(n, NBDExport, eject_notifier);
1040     nbd_export_close(exp);
1041 }
1042 
1043 NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset, off_t size,
1044                           uint16_t nbdflags, void (*close)(NBDExport *),
1045                           bool writethrough, BlockBackend *on_eject_blk,
1046                           Error **errp)
1047 {
1048     BlockBackend *blk;
1049     NBDExport *exp = g_malloc0(sizeof(NBDExport));
1050     uint64_t perm;
1051     int ret;
1052 
1053     /* Don't allow resize while the NBD server is running, otherwise we don't
1054      * care what happens with the node. */
1055     perm = BLK_PERM_CONSISTENT_READ;
1056     if ((nbdflags & NBD_FLAG_READ_ONLY) == 0) {
1057         perm |= BLK_PERM_WRITE;
1058     }
1059     blk = blk_new(perm, BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
1060                         BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD);
1061     ret = blk_insert_bs(blk, bs, errp);
1062     if (ret < 0) {
1063         goto fail;
1064     }
1065     blk_set_enable_write_cache(blk, !writethrough);
1066 
1067     exp->refcount = 1;
1068     QTAILQ_INIT(&exp->clients);
1069     exp->blk = blk;
1070     exp->dev_offset = dev_offset;
1071     exp->nbdflags = nbdflags;
1072     exp->size = size < 0 ? blk_getlength(blk) : size;
1073     if (exp->size < 0) {
1074         error_setg_errno(errp, -exp->size,
1075                          "Failed to determine the NBD export's length");
1076         goto fail;
1077     }
1078     exp->size -= exp->size % BDRV_SECTOR_SIZE;
1079 
1080     exp->close = close;
1081     exp->ctx = blk_get_aio_context(blk);
1082     blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
1083 
1084     if (on_eject_blk) {
1085         blk_ref(on_eject_blk);
1086         exp->eject_notifier_blk = on_eject_blk;
1087         exp->eject_notifier.notify = nbd_eject_notifier;
1088         blk_add_remove_bs_notifier(on_eject_blk, &exp->eject_notifier);
1089     }
1090 
1091     /*
1092      * NBD exports are used for non-shared storage migration.  Make sure
1093      * that BDRV_O_INACTIVE is cleared and the image is ready for write
1094      * access since the export could be available before migration handover.
1095      */
1096     aio_context_acquire(exp->ctx);
1097     blk_invalidate_cache(blk, NULL);
1098     aio_context_release(exp->ctx);
1099     return exp;
1100 
1101 fail:
1102     blk_unref(blk);
1103     g_free(exp);
1104     return NULL;
1105 }
1106 
1107 NBDExport *nbd_export_find(const char *name)
1108 {
1109     NBDExport *exp;
1110     QTAILQ_FOREACH(exp, &exports, next) {
1111         if (strcmp(name, exp->name) == 0) {
1112             return exp;
1113         }
1114     }
1115 
1116     return NULL;
1117 }
1118 
1119 void nbd_export_set_name(NBDExport *exp, const char *name)
1120 {
1121     if (exp->name == name) {
1122         return;
1123     }
1124 
1125     nbd_export_get(exp);
1126     if (exp->name != NULL) {
1127         g_free(exp->name);
1128         exp->name = NULL;
1129         QTAILQ_REMOVE(&exports, exp, next);
1130         nbd_export_put(exp);
1131     }
1132     if (name != NULL) {
1133         nbd_export_get(exp);
1134         exp->name = g_strdup(name);
1135         QTAILQ_INSERT_TAIL(&exports, exp, next);
1136     }
1137     nbd_export_put(exp);
1138 }
1139 
1140 void nbd_export_set_description(NBDExport *exp, const char *description)
1141 {
1142     g_free(exp->description);
1143     exp->description = g_strdup(description);
1144 }
1145 
1146 void nbd_export_close(NBDExport *exp)
1147 {
1148     NBDClient *client, *next;
1149 
1150     nbd_export_get(exp);
1151     QTAILQ_FOREACH_SAFE(client, &exp->clients, next, next) {
1152         client_close(client, true);
1153     }
1154     nbd_export_set_name(exp, NULL);
1155     nbd_export_set_description(exp, NULL);
1156     nbd_export_put(exp);
1157 }
1158 
1159 void nbd_export_get(NBDExport *exp)
1160 {
1161     assert(exp->refcount > 0);
1162     exp->refcount++;
1163 }
1164 
1165 void nbd_export_put(NBDExport *exp)
1166 {
1167     assert(exp->refcount > 0);
1168     if (exp->refcount == 1) {
1169         nbd_export_close(exp);
1170     }
1171 
1172     if (--exp->refcount == 0) {
1173         assert(exp->name == NULL);
1174         assert(exp->description == NULL);
1175 
1176         if (exp->close) {
1177             exp->close(exp);
1178         }
1179 
1180         if (exp->blk) {
1181             if (exp->eject_notifier_blk) {
1182                 notifier_remove(&exp->eject_notifier);
1183                 blk_unref(exp->eject_notifier_blk);
1184             }
1185             blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
1186                                             blk_aio_detach, exp);
1187             blk_unref(exp->blk);
1188             exp->blk = NULL;
1189         }
1190 
1191         g_free(exp);
1192     }
1193 }
1194 
1195 BlockBackend *nbd_export_get_blockdev(NBDExport *exp)
1196 {
1197     return exp->blk;
1198 }
1199 
1200 void nbd_export_close_all(void)
1201 {
1202     NBDExport *exp, *next;
1203 
1204     QTAILQ_FOREACH_SAFE(exp, &exports, next, next) {
1205         nbd_export_close(exp);
1206     }
1207 }
1208 
1209 static int nbd_co_send_reply(NBDRequestData *req, NBDReply *reply, int len,
1210                              Error **errp)
1211 {
1212     NBDClient *client = req->client;
1213     int ret;
1214 
1215     g_assert(qemu_in_coroutine());
1216 
1217     trace_nbd_co_send_reply(reply->handle, reply->error, len);
1218 
1219     qemu_co_mutex_lock(&client->send_lock);
1220     client->send_coroutine = qemu_coroutine_self();
1221 
1222     if (!len) {
1223         ret = nbd_send_reply(client->ioc, reply, errp);
1224     } else {
1225         qio_channel_set_cork(client->ioc, true);
1226         ret = nbd_send_reply(client->ioc, reply, errp);
1227         if (ret == 0) {
1228             ret = nbd_write(client->ioc, req->data, len, errp);
1229             if (ret < 0) {
1230                 ret = -EIO;
1231             }
1232         }
1233         qio_channel_set_cork(client->ioc, false);
1234     }
1235 
1236     client->send_coroutine = NULL;
1237     qemu_co_mutex_unlock(&client->send_lock);
1238     return ret;
1239 }
1240 
1241 /* nbd_co_receive_request
1242  * Collect a client request. Return 0 if request looks valid, -EIO to drop
1243  * connection right away, and any other negative value to report an error to
1244  * the client (although the caller may still need to disconnect after reporting
1245  * the error).
1246  */
1247 static int nbd_co_receive_request(NBDRequestData *req, NBDRequest *request,
1248                                   Error **errp)
1249 {
1250     NBDClient *client = req->client;
1251 
1252     g_assert(qemu_in_coroutine());
1253     assert(client->recv_coroutine == qemu_coroutine_self());
1254     if (nbd_receive_request(client->ioc, request, errp) < 0) {
1255         return -EIO;
1256     }
1257 
1258     trace_nbd_co_receive_request_decode_type(request->handle, request->type,
1259                                              nbd_cmd_lookup(request->type));
1260 
1261     if (request->type != NBD_CMD_WRITE) {
1262         /* No payload, we are ready to read the next request.  */
1263         req->complete = true;
1264     }
1265 
1266     if (request->type == NBD_CMD_DISC) {
1267         /* Special case: we're going to disconnect without a reply,
1268          * whether or not flags, from, or len are bogus */
1269         return -EIO;
1270     }
1271 
1272     /* Check for sanity in the parameters, part 1.  Defer as many
1273      * checks as possible until after reading any NBD_CMD_WRITE
1274      * payload, so we can try and keep the connection alive.  */
1275     if ((request->from + request->len) < request->from) {
1276         error_setg(errp,
1277                    "integer overflow detected, you're probably being attacked");
1278         return -EINVAL;
1279     }
1280 
1281     if (request->type == NBD_CMD_READ || request->type == NBD_CMD_WRITE) {
1282         if (request->len > NBD_MAX_BUFFER_SIZE) {
1283             error_setg(errp, "len (%" PRIu32" ) is larger than max len (%u)",
1284                        request->len, NBD_MAX_BUFFER_SIZE);
1285             return -EINVAL;
1286         }
1287 
1288         req->data = blk_try_blockalign(client->exp->blk, request->len);
1289         if (req->data == NULL) {
1290             error_setg(errp, "No memory");
1291             return -ENOMEM;
1292         }
1293     }
1294     if (request->type == NBD_CMD_WRITE) {
1295         if (nbd_read(client->ioc, req->data, request->len, errp) < 0) {
1296             error_prepend(errp, "reading from socket failed: ");
1297             return -EIO;
1298         }
1299         req->complete = true;
1300 
1301         trace_nbd_co_receive_request_payload_received(request->handle,
1302                                                       request->len);
1303     }
1304 
1305     /* Sanity checks, part 2. */
1306     if (request->from + request->len > client->exp->size) {
1307         error_setg(errp, "operation past EOF; From: %" PRIu64 ", Len: %" PRIu32
1308                    ", Size: %" PRIu64, request->from, request->len,
1309                    (uint64_t)client->exp->size);
1310         return request->type == NBD_CMD_WRITE ? -ENOSPC : -EINVAL;
1311     }
1312     if (request->flags & ~(NBD_CMD_FLAG_FUA | NBD_CMD_FLAG_NO_HOLE)) {
1313         error_setg(errp, "unsupported flags (got 0x%x)", request->flags);
1314         return -EINVAL;
1315     }
1316     if (request->type != NBD_CMD_WRITE_ZEROES &&
1317         (request->flags & NBD_CMD_FLAG_NO_HOLE)) {
1318         error_setg(errp, "unexpected flags (got 0x%x)", request->flags);
1319         return -EINVAL;
1320     }
1321 
1322     return 0;
1323 }
1324 
1325 /* Owns a reference to the NBDClient passed as opaque.  */
1326 static coroutine_fn void nbd_trip(void *opaque)
1327 {
1328     NBDClient *client = opaque;
1329     NBDExport *exp = client->exp;
1330     NBDRequestData *req;
1331     NBDRequest request = { 0 };    /* GCC thinks it can be used uninitialized */
1332     NBDReply reply;
1333     int ret;
1334     int flags;
1335     int reply_data_len = 0;
1336     Error *local_err = NULL;
1337 
1338     trace_nbd_trip();
1339     if (client->closing) {
1340         nbd_client_put(client);
1341         return;
1342     }
1343 
1344     req = nbd_request_get(client);
1345     ret = nbd_co_receive_request(req, &request, &local_err);
1346     client->recv_coroutine = NULL;
1347     nbd_client_receive_next_request(client);
1348     if (ret == -EIO) {
1349         goto disconnect;
1350     }
1351 
1352     reply.handle = request.handle;
1353     reply.error = 0;
1354 
1355     if (ret < 0) {
1356         reply.error = -ret;
1357         goto reply;
1358     }
1359 
1360     if (client->closing) {
1361         /*
1362          * The client may be closed when we are blocked in
1363          * nbd_co_receive_request()
1364          */
1365         goto done;
1366     }
1367 
1368     switch (request.type) {
1369     case NBD_CMD_READ:
1370         /* XXX: NBD Protocol only documents use of FUA with WRITE */
1371         if (request.flags & NBD_CMD_FLAG_FUA) {
1372             ret = blk_co_flush(exp->blk);
1373             if (ret < 0) {
1374                 error_setg_errno(&local_err, -ret, "flush failed");
1375                 reply.error = -ret;
1376                 break;
1377             }
1378         }
1379 
1380         ret = blk_pread(exp->blk, request.from + exp->dev_offset,
1381                         req->data, request.len);
1382         if (ret < 0) {
1383             error_setg_errno(&local_err, -ret, "reading from file failed");
1384             reply.error = -ret;
1385             break;
1386         }
1387 
1388         reply_data_len = request.len;
1389 
1390         break;
1391     case NBD_CMD_WRITE:
1392         if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
1393             reply.error = EROFS;
1394             break;
1395         }
1396 
1397         flags = 0;
1398         if (request.flags & NBD_CMD_FLAG_FUA) {
1399             flags |= BDRV_REQ_FUA;
1400         }
1401         ret = blk_pwrite(exp->blk, request.from + exp->dev_offset,
1402                          req->data, request.len, flags);
1403         if (ret < 0) {
1404             error_setg_errno(&local_err, -ret, "writing to file failed");
1405             reply.error = -ret;
1406         }
1407 
1408         break;
1409     case NBD_CMD_WRITE_ZEROES:
1410         if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
1411             error_setg(&local_err, "Server is read-only, return error");
1412             reply.error = EROFS;
1413             break;
1414         }
1415 
1416         flags = 0;
1417         if (request.flags & NBD_CMD_FLAG_FUA) {
1418             flags |= BDRV_REQ_FUA;
1419         }
1420         if (!(request.flags & NBD_CMD_FLAG_NO_HOLE)) {
1421             flags |= BDRV_REQ_MAY_UNMAP;
1422         }
1423         ret = blk_pwrite_zeroes(exp->blk, request.from + exp->dev_offset,
1424                                 request.len, flags);
1425         if (ret < 0) {
1426             error_setg_errno(&local_err, -ret, "writing to file failed");
1427             reply.error = -ret;
1428         }
1429 
1430         break;
1431     case NBD_CMD_DISC:
1432         /* unreachable, thanks to special case in nbd_co_receive_request() */
1433         abort();
1434 
1435     case NBD_CMD_FLUSH:
1436         ret = blk_co_flush(exp->blk);
1437         if (ret < 0) {
1438             error_setg_errno(&local_err, -ret, "flush failed");
1439             reply.error = -ret;
1440         }
1441 
1442         break;
1443     case NBD_CMD_TRIM:
1444         ret = blk_co_pdiscard(exp->blk, request.from + exp->dev_offset,
1445                               request.len);
1446         if (ret < 0) {
1447             error_setg_errno(&local_err, -ret, "discard failed");
1448             reply.error = -ret;
1449         }
1450 
1451         break;
1452     default:
1453         error_setg(&local_err, "invalid request type (%" PRIu32 ") received",
1454                    request.type);
1455         reply.error = EINVAL;
1456     }
1457 
1458 reply:
1459     if (local_err) {
1460         /* If we are here local_err is not fatal error, already stored in
1461          * reply.error */
1462         error_report_err(local_err);
1463         local_err = NULL;
1464     }
1465 
1466     if (nbd_co_send_reply(req, &reply, reply_data_len, &local_err) < 0) {
1467         error_prepend(&local_err, "Failed to send reply: ");
1468         goto disconnect;
1469     }
1470 
1471     /* We must disconnect after NBD_CMD_WRITE if we did not
1472      * read the payload.
1473      */
1474     if (!req->complete) {
1475         error_setg(&local_err, "Request handling failed in intermediate state");
1476         goto disconnect;
1477     }
1478 
1479 done:
1480     nbd_request_put(req);
1481     nbd_client_put(client);
1482     return;
1483 
1484 disconnect:
1485     if (local_err) {
1486         error_reportf_err(local_err, "Disconnect client, due to: ");
1487     }
1488     nbd_request_put(req);
1489     client_close(client, true);
1490     nbd_client_put(client);
1491 }
1492 
1493 static void nbd_client_receive_next_request(NBDClient *client)
1494 {
1495     if (!client->recv_coroutine && client->nb_requests < MAX_NBD_REQUESTS) {
1496         nbd_client_get(client);
1497         client->recv_coroutine = qemu_coroutine_create(nbd_trip, client);
1498         aio_co_schedule(client->exp->ctx, client->recv_coroutine);
1499     }
1500 }
1501 
1502 static coroutine_fn void nbd_co_client_start(void *opaque)
1503 {
1504     NBDClient *client = opaque;
1505     NBDExport *exp = client->exp;
1506     Error *local_err = NULL;
1507 
1508     if (exp) {
1509         nbd_export_get(exp);
1510         QTAILQ_INSERT_TAIL(&exp->clients, client, next);
1511     }
1512     qemu_co_mutex_init(&client->send_lock);
1513 
1514     if (nbd_negotiate(client, &local_err)) {
1515         if (local_err) {
1516             error_report_err(local_err);
1517         }
1518         client_close(client, false);
1519         return;
1520     }
1521 
1522     nbd_client_receive_next_request(client);
1523 }
1524 
1525 /*
1526  * Create a new client listener on the given export @exp, using the
1527  * given channel @sioc.  Begin servicing it in a coroutine.  When the
1528  * connection closes, call @close_fn with an indication of whether the
1529  * client completed negotiation.
1530  */
1531 void nbd_client_new(NBDExport *exp,
1532                     QIOChannelSocket *sioc,
1533                     QCryptoTLSCreds *tlscreds,
1534                     const char *tlsaclname,
1535                     void (*close_fn)(NBDClient *, bool))
1536 {
1537     NBDClient *client;
1538     Coroutine *co;
1539 
1540     client = g_malloc0(sizeof(NBDClient));
1541     client->refcount = 1;
1542     client->exp = exp;
1543     client->tlscreds = tlscreds;
1544     if (tlscreds) {
1545         object_ref(OBJECT(client->tlscreds));
1546     }
1547     client->tlsaclname = g_strdup(tlsaclname);
1548     client->sioc = sioc;
1549     object_ref(OBJECT(client->sioc));
1550     client->ioc = QIO_CHANNEL(sioc);
1551     object_ref(OBJECT(client->ioc));
1552     client->close_fn = close_fn;
1553 
1554     co = qemu_coroutine_create(nbd_co_client_start, client);
1555     qemu_coroutine_enter(co);
1556 }
1557