include/block/nbd.h

   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 ret;
 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     int ret = nbd_read(ioc, val, sizeof(*val), desc, errp);             \
 379     if (ret < 0) {                                                      \
 380         return ret;                                                     \
 381     }                                                                   \
 382     *val = be##bits##_to_cpu(*val);                                     \
 383     return 0;                                                           \
 384 }
 385
 386 DEF_NBD_READ_N(16) /* Defines nbd_read16(). */
 387 DEF_NBD_READ_N(32) /* Defines nbd_read32(). */
 388 DEF_NBD_READ_N(64) /* Defines nbd_read64(). */
 389
 390 #undef DEF_NBD_READ_N
 391
 392 static inline bool nbd_reply_is_simple(NBDReply *reply)
 393 {
 394     return reply->magic == NBD_SIMPLE_REPLY_MAGIC;
 395 }
 396
 397 static inline bool nbd_reply_is_structured(NBDReply *reply)
 398 {
 399     return reply->magic == NBD_STRUCTURED_REPLY_MAGIC;
 400 }
 401
 402 const char *nbd_reply_type_lookup(uint16_t type);
 403 const char *nbd_opt_lookup(uint32_t opt);
 404 const char *nbd_rep_lookup(uint32_t rep);
 405 const char *nbd_info_lookup(uint16_t info);
 406 const char *nbd_cmd_lookup(uint16_t info);
 407 const char *nbd_err_lookup(int err);
 408
 409 #endif