include/block/nbd.h

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