xref: /qemu/include/block/nbd.h (revision e361a772) 
1 /*
2  *  Copyright (C) 2016-2019 Red Hat, Inc.
3  *  Copyright (C) 2005  Anthony Liguori <anthony@codemonkey.ws>
4  *
5  *  Network Block Device
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 #ifndef NBD_H
21 #define NBD_H
22 
23 #include "qapi/qapi-types-block.h"
24 #include "io/channel-socket.h"
25 #include "crypto/tlscreds.h"
26 
27 /* Handshake phase structs - this struct is passed on the wire */
28 
29 struct NBDOption {
30     uint64_t magic; /* NBD_OPTS_MAGIC */
31     uint32_t option; /* NBD_OPT_* */
32     uint32_t length;
33 } QEMU_PACKED;
34 typedef struct NBDOption NBDOption;
35 
36 struct NBDOptionReply {
37     uint64_t magic; /* NBD_REP_MAGIC */
38     uint32_t option; /* NBD_OPT_* */
39     uint32_t type; /* NBD_REP_* */
40     uint32_t length;
41 } QEMU_PACKED;
42 typedef struct NBDOptionReply NBDOptionReply;
43 
44 typedef struct NBDOptionReplyMetaContext {
45     NBDOptionReply h; /* h.type = NBD_REP_META_CONTEXT, h.length > 4 */
46     uint32_t context_id;
47     /* meta context name follows */
48 } QEMU_PACKED NBDOptionReplyMetaContext;
49 
50 /* Transmission phase structs
51  *
52  * Note: these are _NOT_ the same as the network representation of an NBD
53  * request and reply!
54  */
55 struct NBDRequest {
56     uint64_t handle;
57     uint64_t from;
58     uint32_t len;
59     uint16_t flags; /* NBD_CMD_FLAG_* */
60     uint16_t type; /* NBD_CMD_* */
61 };
62 typedef struct NBDRequest NBDRequest;
63 
64 typedef struct NBDSimpleReply {
65     uint32_t magic;  /* NBD_SIMPLE_REPLY_MAGIC */
66     uint32_t error;
67     uint64_t handle;
68 } QEMU_PACKED NBDSimpleReply;
69 
70 /* Header of all structured replies */
71 typedef struct NBDStructuredReplyChunk {
72     uint32_t magic;  /* NBD_STRUCTURED_REPLY_MAGIC */
73     uint16_t flags;  /* combination of NBD_REPLY_FLAG_* */
74     uint16_t type;   /* NBD_REPLY_TYPE_* */
75     uint64_t handle; /* request handle */
76     uint32_t length; /* length of payload */
77 } QEMU_PACKED NBDStructuredReplyChunk;
78 
79 typedef union NBDReply {
80     NBDSimpleReply simple;
81     NBDStructuredReplyChunk structured;
82     struct {
83         /* @magic and @handle fields have the same offset and size both in
84          * simple reply and structured reply chunk, so let them be accessible
85          * without ".simple." or ".structured." specification
86          */
87         uint32_t magic;
88         uint32_t _skip;
89         uint64_t handle;
90     } QEMU_PACKED;
91 } NBDReply;
92 
93 /* Header of chunk for NBD_REPLY_TYPE_OFFSET_DATA */
94 typedef struct NBDStructuredReadData {
95     NBDStructuredReplyChunk h; /* h.length >= 9 */
96     uint64_t offset;
97     /* At least one byte of data payload follows, calculated from h.length */
98 } QEMU_PACKED NBDStructuredReadData;
99 
100 /* Complete chunk for NBD_REPLY_TYPE_OFFSET_HOLE */
101 typedef struct NBDStructuredReadHole {
102     NBDStructuredReplyChunk h; /* h.length == 12 */
103     uint64_t offset;
104     uint32_t length;
105 } QEMU_PACKED NBDStructuredReadHole;
106 
107 /* Header of all NBD_REPLY_TYPE_ERROR* errors */
108 typedef struct NBDStructuredError {
109     NBDStructuredReplyChunk h; /* h.length >= 6 */
110     uint32_t error;
111     uint16_t message_length;
112 } QEMU_PACKED NBDStructuredError;
113 
114 /* Header of NBD_REPLY_TYPE_BLOCK_STATUS */
115 typedef struct NBDStructuredMeta {
116     NBDStructuredReplyChunk h; /* h.length >= 12 (at least one extent) */
117     uint32_t context_id;
118     /* extents follows */
119 } QEMU_PACKED NBDStructuredMeta;
120 
121 /* Extent chunk for NBD_REPLY_TYPE_BLOCK_STATUS */
122 typedef struct NBDExtent {
123     uint32_t length;
124     uint32_t flags; /* NBD_STATE_* */
125 } QEMU_PACKED NBDExtent;
126 
127 /* Transmission (export) flags: sent from server to client during handshake,
128    but describe what will happen during transmission */
129 #define NBD_FLAG_HAS_FLAGS         (1 << 0) /* Flags are there */
130 #define NBD_FLAG_READ_ONLY         (1 << 1) /* Device is read-only */
131 #define NBD_FLAG_SEND_FLUSH        (1 << 2) /* Send FLUSH */
132 #define NBD_FLAG_SEND_FUA          (1 << 3) /* Send FUA (Force Unit Access) */
133 #define NBD_FLAG_ROTATIONAL        (1 << 4) /* Use elevator algorithm -
134                                                rotational media */
135 #define NBD_FLAG_SEND_TRIM         (1 << 5) /* Send TRIM (discard) */
136 #define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6) /* Send WRITE_ZEROES */
137 #define NBD_FLAG_SEND_DF           (1 << 7) /* Send DF (Do not Fragment) */
138 #define NBD_FLAG_CAN_MULTI_CONN    (1 << 8) /* Multi-client cache consistent */
139 #define NBD_FLAG_SEND_RESIZE       (1 << 9) /* Send resize */
140 #define NBD_FLAG_SEND_CACHE        (1 << 10) /* Send CACHE (prefetch) */
141 
142 /* New-style handshake (global) flags, sent from server to client, and
143    control what will happen during handshake phase. */
144 #define NBD_FLAG_FIXED_NEWSTYLE   (1 << 0) /* Fixed newstyle protocol. */
145 #define NBD_FLAG_NO_ZEROES        (1 << 1) /* End handshake without zeroes. */
146 
147 /* New-style client flags, sent from client to server to control what happens
148    during handshake phase. */
149 #define NBD_FLAG_C_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */
150 #define NBD_FLAG_C_NO_ZEROES      (1 << 1) /* End handshake without zeroes. */
151 
152 /* Option requests. */
153 #define NBD_OPT_EXPORT_NAME       (1)
154 #define NBD_OPT_ABORT             (2)
155 #define NBD_OPT_LIST              (3)
156 /* #define NBD_OPT_PEEK_EXPORT    (4) not in use */
157 #define NBD_OPT_STARTTLS          (5)
158 #define NBD_OPT_INFO              (6)
159 #define NBD_OPT_GO                (7)
160 #define NBD_OPT_STRUCTURED_REPLY  (8)
161 #define NBD_OPT_LIST_META_CONTEXT (9)
162 #define NBD_OPT_SET_META_CONTEXT  (10)
163 
164 /* Option reply types. */
165 #define NBD_REP_ERR(value) ((UINT32_C(1) << 31) | (value))
166 
167 #define NBD_REP_ACK             (1)    /* Data sending finished. */
168 #define NBD_REP_SERVER          (2)    /* Export description. */
169 #define NBD_REP_INFO            (3)    /* NBD_OPT_INFO/GO. */
170 #define NBD_REP_META_CONTEXT    (4)    /* NBD_OPT_{LIST,SET}_META_CONTEXT */
171 
172 #define NBD_REP_ERR_UNSUP           NBD_REP_ERR(1)  /* Unknown option */
173 #define NBD_REP_ERR_POLICY          NBD_REP_ERR(2)  /* Server denied */
174 #define NBD_REP_ERR_INVALID         NBD_REP_ERR(3)  /* Invalid length */
175 #define NBD_REP_ERR_PLATFORM        NBD_REP_ERR(4)  /* Not compiled in */
176 #define NBD_REP_ERR_TLS_REQD        NBD_REP_ERR(5)  /* TLS required */
177 #define NBD_REP_ERR_UNKNOWN         NBD_REP_ERR(6)  /* Export unknown */
178 #define NBD_REP_ERR_SHUTDOWN        NBD_REP_ERR(7)  /* Server shutting down */
179 #define NBD_REP_ERR_BLOCK_SIZE_REQD NBD_REP_ERR(8)  /* Need INFO_BLOCK_SIZE */
180 
181 /* Info types, used during NBD_REP_INFO */
182 #define NBD_INFO_EXPORT         0
183 #define NBD_INFO_NAME           1
184 #define NBD_INFO_DESCRIPTION    2
185 #define NBD_INFO_BLOCK_SIZE     3
186 
187 /* Request flags, sent from client to server during transmission phase */
188 #define NBD_CMD_FLAG_FUA        (1 << 0) /* 'force unit access' during write */
189 #define NBD_CMD_FLAG_NO_HOLE    (1 << 1) /* don't punch hole on zero run */
190 #define NBD_CMD_FLAG_DF         (1 << 2) /* don't fragment structured read */
191 #define NBD_CMD_FLAG_REQ_ONE    (1 << 3) /* only one extent in BLOCK_STATUS
192                                           * reply chunk */
193 
194 /* Supported request types */
195 enum {
196     NBD_CMD_READ = 0,
197     NBD_CMD_WRITE = 1,
198     NBD_CMD_DISC = 2,
199     NBD_CMD_FLUSH = 3,
200     NBD_CMD_TRIM = 4,
201     NBD_CMD_CACHE = 5,
202     NBD_CMD_WRITE_ZEROES = 6,
203     NBD_CMD_BLOCK_STATUS = 7,
204 };
205 
206 #define NBD_DEFAULT_PORT	10809
207 
208 /* Maximum size of a single READ/WRITE data buffer */
209 #define NBD_MAX_BUFFER_SIZE (32 * 1024 * 1024)
210 
211 /* Maximum size of an export name. The NBD spec requires 256 and
212  * suggests that servers support up to 4096, but we stick to only the
213  * required size so that we can stack-allocate the names, and because
214  * going larger would require an audit of more code to make sure we
215  * aren't overflowing some other buffer. */
216 #define NBD_MAX_NAME_SIZE 256
217 
218 /* Two types of reply structures */
219 #define NBD_SIMPLE_REPLY_MAGIC      0x67446698
220 #define NBD_STRUCTURED_REPLY_MAGIC  0x668e33ef
221 
222 /* Structured reply flags */
223 #define NBD_REPLY_FLAG_DONE          (1 << 0) /* This reply-chunk is last */
224 
225 /* Structured reply types */
226 #define NBD_REPLY_ERR(value)         ((1 << 15) | (value))
227 
228 #define NBD_REPLY_TYPE_NONE          0
229 #define NBD_REPLY_TYPE_OFFSET_DATA   1
230 #define NBD_REPLY_TYPE_OFFSET_HOLE   2
231 #define NBD_REPLY_TYPE_BLOCK_STATUS  5
232 #define NBD_REPLY_TYPE_ERROR         NBD_REPLY_ERR(1)
233 #define NBD_REPLY_TYPE_ERROR_OFFSET  NBD_REPLY_ERR(2)
234 
235 /* Extent flags for base:allocation in NBD_REPLY_TYPE_BLOCK_STATUS */
236 #define NBD_STATE_HOLE (1 << 0)
237 #define NBD_STATE_ZERO (1 << 1)
238 
239 /* Extent flags for qemu:dirty-bitmap in NBD_REPLY_TYPE_BLOCK_STATUS */
240 #define NBD_STATE_DIRTY (1 << 0)
241 
242 static inline bool nbd_reply_type_is_error(int type)
243 {
244     return type & (1 << 15);
245 }
246 
247 /* NBD errors are based on errno numbers, so there is a 1:1 mapping,
248  * but only a limited set of errno values is specified in the protocol.
249  * Everything else is squashed to EINVAL.
250  */
251 #define NBD_SUCCESS    0
252 #define NBD_EPERM      1
253 #define NBD_EIO        5
254 #define NBD_ENOMEM     12
255 #define NBD_EINVAL     22
256 #define NBD_ENOSPC     28
257 #define NBD_EOVERFLOW  75
258 #define NBD_ESHUTDOWN  108
259 
260 /* Details collected by NBD_OPT_EXPORT_NAME and NBD_OPT_GO */
261 struct NBDExportInfo {
262     /* Set by client before nbd_receive_negotiate() */
263     bool request_sizes;
264     char *x_dirty_bitmap;
265 
266     /* Set by client before nbd_receive_negotiate(), or by server results
267      * during nbd_receive_export_list() */
268     char *name; /* must be non-NULL */
269 
270     /* In-out fields, set by client before nbd_receive_negotiate() and
271      * updated by server results during nbd_receive_negotiate() */
272     bool structured_reply;
273     bool base_allocation; /* base:allocation context for NBD_CMD_BLOCK_STATUS */
274 
275     /* Set by server results during nbd_receive_negotiate() and
276      * nbd_receive_export_list() */
277     uint64_t size;
278     uint16_t flags;
279     uint32_t min_block;
280     uint32_t opt_block;
281     uint32_t max_block;
282 
283     uint32_t context_id;
284 
285     /* Set by server results during nbd_receive_export_list() */
286     char *description;
287     int n_contexts;
288     char **contexts;
289 };
290 typedef struct NBDExportInfo NBDExportInfo;
291 
292 int nbd_receive_negotiate(QIOChannel *ioc, QCryptoTLSCreds *tlscreds,
293                           const char *hostname, QIOChannel **outioc,
294                           NBDExportInfo *info, Error **errp);
295 void nbd_free_export_list(NBDExportInfo *info, int count);
296 int nbd_receive_export_list(QIOChannel *ioc, QCryptoTLSCreds *tlscreds,
297                             const char *hostname, NBDExportInfo **info,
298                             Error **errp);
299 int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info,
300              Error **errp);
301 int nbd_send_request(QIOChannel *ioc, NBDRequest *request);
302 int nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp);
303 int nbd_client(int fd);
304 int nbd_disconnect(int fd);
305 int nbd_errno_to_system_errno(int err);
306 
307 typedef struct NBDExport NBDExport;
308 typedef struct NBDClient NBDClient;
309 
310 NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
311                           uint64_t size, const char *name, const char *desc,
312                           const char *bitmap, uint16_t nbdflags,
313                           void (*close)(NBDExport *), bool writethrough,
314                           BlockBackend *on_eject_blk, Error **errp);
315 void nbd_export_close(NBDExport *exp);
316 void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp);
317 void nbd_export_get(NBDExport *exp);
318 void nbd_export_put(NBDExport *exp);
319 
320 BlockBackend *nbd_export_get_blockdev(NBDExport *exp);
321 
322 NBDExport *nbd_export_find(const char *name);
323 void nbd_export_close_all(void);
324 
325 void nbd_client_new(QIOChannelSocket *sioc,
326                     QCryptoTLSCreds *tlscreds,
327                     const char *tlsaclname,
328                     void (*close_fn)(NBDClient *, bool));
329 void nbd_client_get(NBDClient *client);
330 void nbd_client_put(NBDClient *client);
331 
332 void nbd_server_start(SocketAddress *addr, const char *tls_creds,
333                       Error **errp);
334 
335 /* nbd_read
336  * Reads @size bytes from @ioc. Returns 0 on success.
337  */
338 static inline int nbd_read(QIOChannel *ioc, void *buffer, size_t size,
339                            Error **errp)
340 {
341     return qio_channel_read_all(ioc, buffer, size, errp) < 0 ? -EIO : 0;
342 }
343 
344 static inline bool nbd_reply_is_simple(NBDReply *reply)
345 {
346     return reply->magic == NBD_SIMPLE_REPLY_MAGIC;
347 }
348 
349 static inline bool nbd_reply_is_structured(NBDReply *reply)
350 {
351     return reply->magic == NBD_STRUCTURED_REPLY_MAGIC;
352 }
353 
354 const char *nbd_reply_type_lookup(uint16_t type);
355 const char *nbd_opt_lookup(uint32_t opt);
356 const char *nbd_rep_lookup(uint32_t rep);
357 const char *nbd_info_lookup(uint16_t info);
358 const char *nbd_cmd_lookup(uint16_t info);
359 const char *nbd_err_lookup(int err);
360 
361 #endif
362