xref: /openbmc/qemu/include/block/nbd.h (revision 57b3a7d8)
1 /*
2  *  Copyright (C) 2016-2020 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 "block/export.h"
24 #include "io/channel-socket.h"
25 #include "crypto/tlscreds.h"
26 #include "qapi/error.h"
27 
28 extern const BlockExportDriver blk_exp_nbd;
29 
30 /* Handshake phase structs - this struct is passed on the wire */
31 
32 struct NBDOption {
33     uint64_t magic; /* NBD_OPTS_MAGIC */
34     uint32_t option; /* NBD_OPT_* */
35     uint32_t length;
36 } QEMU_PACKED;
37 typedef struct NBDOption NBDOption;
38 
39 struct NBDOptionReply {
40     uint64_t magic; /* NBD_REP_MAGIC */
41     uint32_t option; /* NBD_OPT_* */
42     uint32_t type; /* NBD_REP_* */
43     uint32_t length;
44 } QEMU_PACKED;
45 typedef struct NBDOptionReply NBDOptionReply;
46 
47 typedef struct NBDOptionReplyMetaContext {
48     NBDOptionReply h; /* h.type = NBD_REP_META_CONTEXT, h.length > 4 */
49     uint32_t context_id;
50     /* metadata context name follows */
51 } QEMU_PACKED NBDOptionReplyMetaContext;
52 
53 /* Transmission phase structs
54  *
55  * Note: these are _NOT_ the same as the network representation of an NBD
56  * request and reply!
57  */
58 struct NBDRequest {
59     uint64_t handle;
60     uint64_t from;
61     uint32_t len;
62     uint16_t flags; /* NBD_CMD_FLAG_* */
63     uint16_t type; /* NBD_CMD_* */
64 };
65 typedef struct NBDRequest NBDRequest;
66 
67 typedef struct NBDSimpleReply {
68     uint32_t magic;  /* NBD_SIMPLE_REPLY_MAGIC */
69     uint32_t error;
70     uint64_t handle;
71 } QEMU_PACKED NBDSimpleReply;
72 
73 /* Header of all structured replies */
74 typedef struct NBDStructuredReplyChunk {
75     uint32_t magic;  /* NBD_STRUCTURED_REPLY_MAGIC */
76     uint16_t flags;  /* combination of NBD_REPLY_FLAG_* */
77     uint16_t type;   /* NBD_REPLY_TYPE_* */
78     uint64_t handle; /* request handle */
79     uint32_t length; /* length of payload */
80 } QEMU_PACKED NBDStructuredReplyChunk;
81 
82 typedef union NBDReply {
83     NBDSimpleReply simple;
84     NBDStructuredReplyChunk structured;
85     struct {
86         /* @magic and @handle fields have the same offset and size both in
87          * simple reply and structured reply chunk, so let them be accessible
88          * without ".simple." or ".structured." specification
89          */
90         uint32_t magic;
91         uint32_t _skip;
92         uint64_t handle;
93     } QEMU_PACKED;
94 } NBDReply;
95 
96 /* Header of chunk for NBD_REPLY_TYPE_OFFSET_DATA */
97 typedef struct NBDStructuredReadData {
98     NBDStructuredReplyChunk h; /* h.length >= 9 */
99     uint64_t offset;
100     /* At least one byte of data payload follows, calculated from h.length */
101 } QEMU_PACKED NBDStructuredReadData;
102 
103 /* Complete chunk for NBD_REPLY_TYPE_OFFSET_HOLE */
104 typedef struct NBDStructuredReadHole {
105     NBDStructuredReplyChunk h; /* h.length == 12 */
106     uint64_t offset;
107     uint32_t length;
108 } QEMU_PACKED NBDStructuredReadHole;
109 
110 /* Header of all NBD_REPLY_TYPE_ERROR* errors */
111 typedef struct NBDStructuredError {
112     NBDStructuredReplyChunk h; /* h.length >= 6 */
113     uint32_t error;
114     uint16_t message_length;
115 } QEMU_PACKED NBDStructuredError;
116 
117 /* Header of NBD_REPLY_TYPE_BLOCK_STATUS */
118 typedef struct NBDStructuredMeta {
119     NBDStructuredReplyChunk h; /* h.length >= 12 (at least one extent) */
120     uint32_t context_id;
121     /* extents follows */
122 } QEMU_PACKED NBDStructuredMeta;
123 
124 /* Extent chunk for NBD_REPLY_TYPE_BLOCK_STATUS */
125 typedef struct NBDExtent {
126     uint32_t length;
127     uint32_t flags; /* NBD_STATE_* */
128 } QEMU_PACKED NBDExtent;
129 
130 /* Transmission (export) flags: sent from server to client during handshake,
131    but describe what will happen during transmission */
132 enum {
133     NBD_FLAG_HAS_FLAGS_BIT          =  0, /* Flags are there */
134     NBD_FLAG_READ_ONLY_BIT          =  1, /* Device is read-only */
135     NBD_FLAG_SEND_FLUSH_BIT         =  2, /* Send FLUSH */
136     NBD_FLAG_SEND_FUA_BIT           =  3, /* Send FUA (Force Unit Access) */
137     NBD_FLAG_ROTATIONAL_BIT         =  4, /* Use elevator algorithm -
138                                              rotational media */
139     NBD_FLAG_SEND_TRIM_BIT          =  5, /* Send TRIM (discard) */
140     NBD_FLAG_SEND_WRITE_ZEROES_BIT  =  6, /* Send WRITE_ZEROES */
141     NBD_FLAG_SEND_DF_BIT            =  7, /* Send DF (Do not Fragment) */
142     NBD_FLAG_CAN_MULTI_CONN_BIT     =  8, /* Multi-client cache consistent */
143     NBD_FLAG_SEND_RESIZE_BIT        =  9, /* Send resize */
144     NBD_FLAG_SEND_CACHE_BIT         = 10, /* Send CACHE (prefetch) */
145     NBD_FLAG_SEND_FAST_ZERO_BIT     = 11, /* FAST_ZERO flag for WRITE_ZEROES */
146 };
147 
148 #define NBD_FLAG_HAS_FLAGS         (1 << NBD_FLAG_HAS_FLAGS_BIT)
149 #define NBD_FLAG_READ_ONLY         (1 << NBD_FLAG_READ_ONLY_BIT)
150 #define NBD_FLAG_SEND_FLUSH        (1 << NBD_FLAG_SEND_FLUSH_BIT)
151 #define NBD_FLAG_SEND_FUA          (1 << NBD_FLAG_SEND_FUA_BIT)
152 #define NBD_FLAG_ROTATIONAL        (1 << NBD_FLAG_ROTATIONAL_BIT)
153 #define NBD_FLAG_SEND_TRIM         (1 << NBD_FLAG_SEND_TRIM_BIT)
154 #define NBD_FLAG_SEND_WRITE_ZEROES (1 << NBD_FLAG_SEND_WRITE_ZEROES_BIT)
155 #define NBD_FLAG_SEND_DF           (1 << NBD_FLAG_SEND_DF_BIT)
156 #define NBD_FLAG_CAN_MULTI_CONN    (1 << NBD_FLAG_CAN_MULTI_CONN_BIT)
157 #define NBD_FLAG_SEND_RESIZE       (1 << NBD_FLAG_SEND_RESIZE_BIT)
158 #define NBD_FLAG_SEND_CACHE        (1 << NBD_FLAG_SEND_CACHE_BIT)
159 #define NBD_FLAG_SEND_FAST_ZERO    (1 << NBD_FLAG_SEND_FAST_ZERO_BIT)
160 
161 /* New-style handshake (global) flags, sent from server to client, and
162    control what will happen during handshake phase. */
163 #define NBD_FLAG_FIXED_NEWSTYLE   (1 << 0) /* Fixed newstyle protocol. */
164 #define NBD_FLAG_NO_ZEROES        (1 << 1) /* End handshake without zeroes. */
165 
166 /* New-style client flags, sent from client to server to control what happens
167    during handshake phase. */
168 #define NBD_FLAG_C_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */
169 #define NBD_FLAG_C_NO_ZEROES      (1 << 1) /* End handshake without zeroes. */
170 
171 /* Option requests. */
172 #define NBD_OPT_EXPORT_NAME       (1)
173 #define NBD_OPT_ABORT             (2)
174 #define NBD_OPT_LIST              (3)
175 /* #define NBD_OPT_PEEK_EXPORT    (4) not in use */
176 #define NBD_OPT_STARTTLS          (5)
177 #define NBD_OPT_INFO              (6)
178 #define NBD_OPT_GO                (7)
179 #define NBD_OPT_STRUCTURED_REPLY  (8)
180 #define NBD_OPT_LIST_META_CONTEXT (9)
181 #define NBD_OPT_SET_META_CONTEXT  (10)
182 
183 /* Option reply types. */
184 #define NBD_REP_ERR(value) ((UINT32_C(1) << 31) | (value))
185 
186 #define NBD_REP_ACK             (1)    /* Data sending finished. */
187 #define NBD_REP_SERVER          (2)    /* Export description. */
188 #define NBD_REP_INFO            (3)    /* NBD_OPT_INFO/GO. */
189 #define NBD_REP_META_CONTEXT    (4)    /* NBD_OPT_{LIST,SET}_META_CONTEXT */
190 
191 #define NBD_REP_ERR_UNSUP           NBD_REP_ERR(1)  /* Unknown option */
192 #define NBD_REP_ERR_POLICY          NBD_REP_ERR(2)  /* Server denied */
193 #define NBD_REP_ERR_INVALID         NBD_REP_ERR(3)  /* Invalid length */
194 #define NBD_REP_ERR_PLATFORM        NBD_REP_ERR(4)  /* Not compiled in */
195 #define NBD_REP_ERR_TLS_REQD        NBD_REP_ERR(5)  /* TLS required */
196 #define NBD_REP_ERR_UNKNOWN         NBD_REP_ERR(6)  /* Export unknown */
197 #define NBD_REP_ERR_SHUTDOWN        NBD_REP_ERR(7)  /* Server shutting down */
198 #define NBD_REP_ERR_BLOCK_SIZE_REQD NBD_REP_ERR(8)  /* Need INFO_BLOCK_SIZE */
199 
200 /* Info types, used during NBD_REP_INFO */
201 #define NBD_INFO_EXPORT         0
202 #define NBD_INFO_NAME           1
203 #define NBD_INFO_DESCRIPTION    2
204 #define NBD_INFO_BLOCK_SIZE     3
205 
206 /* Request flags, sent from client to server during transmission phase */
207 #define NBD_CMD_FLAG_FUA        (1 << 0) /* 'force unit access' during write */
208 #define NBD_CMD_FLAG_NO_HOLE    (1 << 1) /* don't punch hole on zero run */
209 #define NBD_CMD_FLAG_DF         (1 << 2) /* don't fragment structured read */
210 #define NBD_CMD_FLAG_REQ_ONE    (1 << 3) /* only one extent in BLOCK_STATUS
211                                           * reply chunk */
212 #define NBD_CMD_FLAG_FAST_ZERO  (1 << 4) /* fail if WRITE_ZEROES is not fast */
213 
214 /* Supported request types */
215 enum {
216     NBD_CMD_READ = 0,
217     NBD_CMD_WRITE = 1,
218     NBD_CMD_DISC = 2,
219     NBD_CMD_FLUSH = 3,
220     NBD_CMD_TRIM = 4,
221     NBD_CMD_CACHE = 5,
222     NBD_CMD_WRITE_ZEROES = 6,
223     NBD_CMD_BLOCK_STATUS = 7,
224 };
225 
226 #define NBD_DEFAULT_PORT	10809
227 
228 /* Maximum size of a single READ/WRITE data buffer */
229 #define NBD_MAX_BUFFER_SIZE (32 * 1024 * 1024)
230 
231 /*
232  * Maximum size of a protocol string (export name, metadata context name,
233  * etc.).  Use malloc rather than stack allocation for storage of a
234  * string.
235  */
236 #define NBD_MAX_STRING_SIZE 4096
237 
238 /* Two types of reply structures */
239 #define NBD_SIMPLE_REPLY_MAGIC      0x67446698
240 #define NBD_STRUCTURED_REPLY_MAGIC  0x668e33ef
241 
242 /* Structured reply flags */
243 #define NBD_REPLY_FLAG_DONE          (1 << 0) /* This reply-chunk is last */
244 
245 /* Structured reply types */
246 #define NBD_REPLY_ERR(value)         ((1 << 15) | (value))
247 
248 #define NBD_REPLY_TYPE_NONE          0
249 #define NBD_REPLY_TYPE_OFFSET_DATA   1
250 #define NBD_REPLY_TYPE_OFFSET_HOLE   2
251 #define NBD_REPLY_TYPE_BLOCK_STATUS  5
252 #define NBD_REPLY_TYPE_ERROR         NBD_REPLY_ERR(1)
253 #define NBD_REPLY_TYPE_ERROR_OFFSET  NBD_REPLY_ERR(2)
254 
255 /* Extent flags for base:allocation in NBD_REPLY_TYPE_BLOCK_STATUS */
256 #define NBD_STATE_HOLE (1 << 0)
257 #define NBD_STATE_ZERO (1 << 1)
258 
259 /* Extent flags for qemu:dirty-bitmap in NBD_REPLY_TYPE_BLOCK_STATUS */
260 #define NBD_STATE_DIRTY (1 << 0)
261 
262 /* No flags needed for qemu:allocation-depth in NBD_REPLY_TYPE_BLOCK_STATUS */
263 
264 static inline bool nbd_reply_type_is_error(int type)
265 {
266     return type & (1 << 15);
267 }
268 
269 /* NBD errors are based on errno numbers, so there is a 1:1 mapping,
270  * but only a limited set of errno values is specified in the protocol.
271  * Everything else is squashed to EINVAL.
272  */
273 #define NBD_SUCCESS    0
274 #define NBD_EPERM      1
275 #define NBD_EIO        5
276 #define NBD_ENOMEM     12
277 #define NBD_EINVAL     22
278 #define NBD_ENOSPC     28
279 #define NBD_EOVERFLOW  75
280 #define NBD_ENOTSUP    95
281 #define NBD_ESHUTDOWN  108
282 
283 /* Details collected by NBD_OPT_EXPORT_NAME and NBD_OPT_GO */
284 struct NBDExportInfo {
285     /* Set by client before nbd_receive_negotiate() */
286     bool request_sizes;
287     char *x_dirty_bitmap;
288 
289     /* Set by client before nbd_receive_negotiate(), or by server results
290      * during nbd_receive_export_list() */
291     char *name; /* must be non-NULL */
292 
293     /* In-out fields, set by client before nbd_receive_negotiate() and
294      * updated by server results during nbd_receive_negotiate() */
295     bool structured_reply;
296     bool base_allocation; /* base:allocation context for NBD_CMD_BLOCK_STATUS */
297 
298     /* Set by server results during nbd_receive_negotiate() and
299      * nbd_receive_export_list() */
300     uint64_t size;
301     uint16_t flags;
302     uint32_t min_block;
303     uint32_t opt_block;
304     uint32_t max_block;
305 
306     uint32_t context_id;
307 
308     /* Set by server results during nbd_receive_export_list() */
309     char *description;
310     int n_contexts;
311     char **contexts;
312 };
313 typedef struct NBDExportInfo NBDExportInfo;
314 
315 int nbd_receive_negotiate(AioContext *aio_context, QIOChannel *ioc,
316                           QCryptoTLSCreds *tlscreds,
317                           const char *hostname, QIOChannel **outioc,
318                           NBDExportInfo *info, Error **errp);
319 void nbd_free_export_list(NBDExportInfo *info, int count);
320 int nbd_receive_export_list(QIOChannel *ioc, QCryptoTLSCreds *tlscreds,
321                             const char *hostname, NBDExportInfo **info,
322                             Error **errp);
323 int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info,
324              Error **errp);
325 int nbd_send_request(QIOChannel *ioc, NBDRequest *request);
326 int coroutine_fn nbd_receive_reply(BlockDriverState *bs, QIOChannel *ioc,
327                                    NBDReply *reply, Error **errp);
328 int nbd_client(int fd);
329 int nbd_disconnect(int fd);
330 int nbd_errno_to_system_errno(int err);
331 
332 typedef struct NBDExport NBDExport;
333 typedef struct NBDClient NBDClient;
334 
335 void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk);
336 
337 AioContext *nbd_export_aio_context(NBDExport *exp);
338 NBDExport *nbd_export_find(const char *name);
339 
340 void nbd_client_new(QIOChannelSocket *sioc,
341                     QCryptoTLSCreds *tlscreds,
342                     const char *tlsauthz,
343                     void (*close_fn)(NBDClient *, bool));
344 void nbd_client_get(NBDClient *client);
345 void nbd_client_put(NBDClient *client);
346 
347 void nbd_server_is_qemu_nbd(bool value);
348 bool nbd_server_is_running(void);
349 void nbd_server_start(SocketAddress *addr, const char *tls_creds,
350                       const char *tls_authz, uint32_t max_connections,
351                       Error **errp);
352 void nbd_server_start_options(NbdServerOptions *arg, Error **errp);
353 
354 /* nbd_read
355  * Reads @size bytes from @ioc. Returns 0 on success.
356  */
357 static inline int nbd_read(QIOChannel *ioc, void *buffer, size_t size,
358                            const char *desc, Error **errp)
359 {
360     ERRP_GUARD();
361     int ret = qio_channel_read_all(ioc, buffer, size, errp) < 0 ? -EIO : 0;
362 
363     if (ret < 0) {
364         if (desc) {
365             error_prepend(errp, "Failed to read %s: ", desc);
366         }
367         return -1;
368     }
369 
370     return 0;
371 }
372 
373 #define DEF_NBD_READ_N(bits)                                            \
374 static inline int nbd_read##bits(QIOChannel *ioc,                       \
375                                  uint##bits##_t *val,                   \
376                                  const char *desc, Error **errp)        \
377 {                                                                       \
378     if (nbd_read(ioc, val, sizeof(*val), desc, errp) < 0) {             \
379         return -1;                                                      \
380     }                                                                   \
381     *val = be##bits##_to_cpu(*val);                                     \
382     return 0;                                                           \
383 }
384 
385 DEF_NBD_READ_N(16) /* Defines nbd_read16(). */
386 DEF_NBD_READ_N(32) /* Defines nbd_read32(). */
387 DEF_NBD_READ_N(64) /* Defines nbd_read64(). */
388 
389 #undef DEF_NBD_READ_N
390 
391 static inline bool nbd_reply_is_simple(NBDReply *reply)
392 {
393     return reply->magic == NBD_SIMPLE_REPLY_MAGIC;
394 }
395 
396 static inline bool nbd_reply_is_structured(NBDReply *reply)
397 {
398     return reply->magic == NBD_STRUCTURED_REPLY_MAGIC;
399 }
400 
401 const char *nbd_reply_type_lookup(uint16_t type);
402 const char *nbd_opt_lookup(uint32_t opt);
403 const char *nbd_rep_lookup(uint32_t rep);
404 const char *nbd_info_lookup(uint16_t info);
405 const char *nbd_cmd_lookup(uint16_t info);
406 const char *nbd_err_lookup(int err);
407 
408 #endif
409