include/block/nbd.h

   1 /*
   2  *  Copyright Red Hat
   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 #include "qemu/bswap.h"
  28
  29 typedef struct NBDExport NBDExport;
  30 typedef struct NBDClient NBDClient;
  31 typedef struct NBDClientConnection NBDClientConnection;
  32
  33 extern const BlockExportDriver blk_exp_nbd;
  34
  35 /* Handshake phase structs - this struct is passed on the wire */
  36
  37 typedef struct NBDOption {
  38     uint64_t magic; /* NBD_OPTS_MAGIC */
  39     uint32_t option; /* NBD_OPT_* */
  40     uint32_t length;
  41 } QEMU_PACKED NBDOption;
  42
  43 typedef struct NBDOptionReply {
  44     uint64_t magic; /* NBD_REP_MAGIC */
  45     uint32_t option; /* NBD_OPT_* */
  46     uint32_t type; /* NBD_REP_* */
  47     uint32_t length;
  48 } QEMU_PACKED NBDOptionReply;
  49
  50 typedef struct NBDOptionReplyMetaContext {
  51     NBDOptionReply h; /* h.type = NBD_REP_META_CONTEXT, h.length > 4 */
  52     uint32_t context_id;
  53     /* metadata context name follows */
  54 } QEMU_PACKED NBDOptionReplyMetaContext;
  55
  56 /* Track results of negotiation */
  57 typedef enum NBDMode {
  58     /* Keep this list in a continuum of increasing features. */
  59     NBD_MODE_OLDSTYLE,     /* server lacks newstyle negotiation */
  60     NBD_MODE_EXPORT_NAME,  /* newstyle but only OPT_EXPORT_NAME safe */
  61     NBD_MODE_SIMPLE,       /* newstyle but only simple replies */
  62     NBD_MODE_STRUCTURED,   /* newstyle, structured replies enabled */
  63     /* TODO add NBD_MODE_EXTENDED */
  64 } NBDMode;
  65
  66 /* Transmission phase structs */
  67
  68 /*
  69  * Note: NBDRequest is _NOT_ the same as the network representation of an NBD
  70  * request!
  71  */
  72 typedef struct NBDRequest {
  73     uint64_t cookie;
  74     uint64_t from;
  75     uint32_t len;
  76     uint16_t flags; /* NBD_CMD_FLAG_* */
  77     uint16_t type;  /* NBD_CMD_* */
  78     NBDMode mode;   /* Determines which network representation to use */
  79 } NBDRequest;
  80
  81 typedef struct NBDSimpleReply {
  82     uint32_t magic;  /* NBD_SIMPLE_REPLY_MAGIC */
  83     uint32_t error;
  84     uint64_t cookie;
  85 } QEMU_PACKED NBDSimpleReply;
  86
  87 /* Header of all structured replies */
  88 typedef struct NBDStructuredReplyChunk {
  89     uint32_t magic;  /* NBD_STRUCTURED_REPLY_MAGIC */
  90     uint16_t flags;  /* combination of NBD_REPLY_FLAG_* */
  91     uint16_t type;   /* NBD_REPLY_TYPE_* */
  92     uint64_t cookie; /* request handle */
  93     uint32_t length; /* length of payload */
  94 } QEMU_PACKED NBDStructuredReplyChunk;
  95
  96 typedef union NBDReply {
  97     NBDSimpleReply simple;
  98     NBDStructuredReplyChunk structured;
  99     struct {
 100         /*
 101          * @magic and @cookie fields have the same offset and size both in
 102          * simple reply and structured reply chunk, so let them be accessible
 103          * without ".simple." or ".structured." specification
 104          */
 105         uint32_t magic;
 106         uint32_t _skip;
 107         uint64_t cookie;
 108     } QEMU_PACKED;
 109 } NBDReply;
 110
 111 /* Header of chunk for NBD_REPLY_TYPE_OFFSET_DATA */
 112 typedef struct NBDStructuredReadData {
 113     /* header's .length >= 9 */
 114     uint64_t offset;
 115     /* At least one byte of data payload follows, calculated from h.length */
 116 } QEMU_PACKED NBDStructuredReadData;
 117
 118 /* Complete chunk for NBD_REPLY_TYPE_OFFSET_HOLE */
 119 typedef struct NBDStructuredReadHole {
 120     /* header's length == 12 */
 121     uint64_t offset;
 122     uint32_t length;
 123 } QEMU_PACKED NBDStructuredReadHole;
 124
 125 /* Header of all NBD_REPLY_TYPE_ERROR* errors */
 126 typedef struct NBDStructuredError {
 127     /* header's length >= 6 */
 128     uint32_t error;
 129     uint16_t message_length;
 130 } QEMU_PACKED NBDStructuredError;
 131
 132 /* Header of NBD_REPLY_TYPE_BLOCK_STATUS */
 133 typedef struct NBDStructuredMeta {
 134     /* header's length >= 12 (at least one extent) */
 135     uint32_t context_id;
 136     /* extents follows */
 137 } QEMU_PACKED NBDStructuredMeta;
 138
 139 /* Extent chunk for NBD_REPLY_TYPE_BLOCK_STATUS */
 140 typedef struct NBDExtent {
 141     uint32_t length;
 142     uint32_t flags; /* NBD_STATE_* */
 143 } QEMU_PACKED NBDExtent;
 144
 145 /* Transmission (export) flags: sent from server to client during handshake,
 146    but describe what will happen during transmission */
 147 enum {
 148     NBD_FLAG_HAS_FLAGS_BIT          =  0, /* Flags are there */
 149     NBD_FLAG_READ_ONLY_BIT          =  1, /* Device is read-only */
 150     NBD_FLAG_SEND_FLUSH_BIT         =  2, /* Send FLUSH */
 151     NBD_FLAG_SEND_FUA_BIT           =  3, /* Send FUA (Force Unit Access) */
 152     NBD_FLAG_ROTATIONAL_BIT         =  4, /* Use elevator algorithm -
 153                                              rotational media */
 154     NBD_FLAG_SEND_TRIM_BIT          =  5, /* Send TRIM (discard) */
 155     NBD_FLAG_SEND_WRITE_ZEROES_BIT  =  6, /* Send WRITE_ZEROES */
 156     NBD_FLAG_SEND_DF_BIT            =  7, /* Send DF (Do not Fragment) */
 157     NBD_FLAG_CAN_MULTI_CONN_BIT     =  8, /* Multi-client cache consistent */
 158     NBD_FLAG_SEND_RESIZE_BIT        =  9, /* Send resize */
 159     NBD_FLAG_SEND_CACHE_BIT         = 10, /* Send CACHE (prefetch) */
 160     NBD_FLAG_SEND_FAST_ZERO_BIT     = 11, /* FAST_ZERO flag for WRITE_ZEROES */
 161 };
 162
 163 #define NBD_FLAG_HAS_FLAGS         (1 << NBD_FLAG_HAS_FLAGS_BIT)
 164 #define NBD_FLAG_READ_ONLY         (1 << NBD_FLAG_READ_ONLY_BIT)
 165 #define NBD_FLAG_SEND_FLUSH        (1 << NBD_FLAG_SEND_FLUSH_BIT)
 166 #define NBD_FLAG_SEND_FUA          (1 << NBD_FLAG_SEND_FUA_BIT)
 167 #define NBD_FLAG_ROTATIONAL        (1 << NBD_FLAG_ROTATIONAL_BIT)
 168 #define NBD_FLAG_SEND_TRIM         (1 << NBD_FLAG_SEND_TRIM_BIT)
 169 #define NBD_FLAG_SEND_WRITE_ZEROES (1 << NBD_FLAG_SEND_WRITE_ZEROES_BIT)
 170 #define NBD_FLAG_SEND_DF           (1 << NBD_FLAG_SEND_DF_BIT)
 171 #define NBD_FLAG_CAN_MULTI_CONN    (1 << NBD_FLAG_CAN_MULTI_CONN_BIT)
 172 #define NBD_FLAG_SEND_RESIZE       (1 << NBD_FLAG_SEND_RESIZE_BIT)
 173 #define NBD_FLAG_SEND_CACHE        (1 << NBD_FLAG_SEND_CACHE_BIT)
 174 #define NBD_FLAG_SEND_FAST_ZERO    (1 << NBD_FLAG_SEND_FAST_ZERO_BIT)
 175
 176 /* New-style handshake (global) flags, sent from server to client, and
 177    control what will happen during handshake phase. */
 178 #define NBD_FLAG_FIXED_NEWSTYLE   (1 << 0) /* Fixed newstyle protocol. */
 179 #define NBD_FLAG_NO_ZEROES        (1 << 1) /* End handshake without zeroes. */
 180
 181 /* New-style client flags, sent from client to server to control what happens
 182    during handshake phase. */
 183 #define NBD_FLAG_C_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */
 184 #define NBD_FLAG_C_NO_ZEROES      (1 << 1) /* End handshake without zeroes. */
 185
 186 /* Option requests. */
 187 #define NBD_OPT_EXPORT_NAME       (1)
 188 #define NBD_OPT_ABORT             (2)
 189 #define NBD_OPT_LIST              (3)
 190 /* #define NBD_OPT_PEEK_EXPORT    (4) not in use */
 191 #define NBD_OPT_STARTTLS          (5)
 192 #define NBD_OPT_INFO              (6)
 193 #define NBD_OPT_GO                (7)
 194 #define NBD_OPT_STRUCTURED_REPLY  (8)
 195 #define NBD_OPT_LIST_META_CONTEXT (9)
 196 #define NBD_OPT_SET_META_CONTEXT  (10)
 197
 198 /* Option reply types. */
 199 #define NBD_REP_ERR(value) ((UINT32_C(1) << 31) | (value))
 200
 201 #define NBD_REP_ACK             (1)    /* Data sending finished. */
 202 #define NBD_REP_SERVER          (2)    /* Export description. */
 203 #define NBD_REP_INFO            (3)    /* NBD_OPT_INFO/GO. */
 204 #define NBD_REP_META_CONTEXT    (4)    /* NBD_OPT_{LIST,SET}_META_CONTEXT */
 205
 206 #define NBD_REP_ERR_UNSUP           NBD_REP_ERR(1)  /* Unknown option */
 207 #define NBD_REP_ERR_POLICY          NBD_REP_ERR(2)  /* Server denied */
 208 #define NBD_REP_ERR_INVALID         NBD_REP_ERR(3)  /* Invalid length */
 209 #define NBD_REP_ERR_PLATFORM        NBD_REP_ERR(4)  /* Not compiled in */
 210 #define NBD_REP_ERR_TLS_REQD        NBD_REP_ERR(5)  /* TLS required */
 211 #define NBD_REP_ERR_UNKNOWN         NBD_REP_ERR(6)  /* Export unknown */
 212 #define NBD_REP_ERR_SHUTDOWN        NBD_REP_ERR(7)  /* Server shutting down */
 213 #define NBD_REP_ERR_BLOCK_SIZE_REQD NBD_REP_ERR(8)  /* Need INFO_BLOCK_SIZE */
 214
 215 /* Info types, used during NBD_REP_INFO */
 216 #define NBD_INFO_EXPORT         0
 217 #define NBD_INFO_NAME           1
 218 #define NBD_INFO_DESCRIPTION    2
 219 #define NBD_INFO_BLOCK_SIZE     3
 220
 221 /* Request flags, sent from client to server during transmission phase */
 222 #define NBD_CMD_FLAG_FUA        (1 << 0) /* 'force unit access' during write */
 223 #define NBD_CMD_FLAG_NO_HOLE    (1 << 1) /* don't punch hole on zero run */
 224 #define NBD_CMD_FLAG_DF         (1 << 2) /* don't fragment structured read */
 225 #define NBD_CMD_FLAG_REQ_ONE    (1 << 3) /* only one extent in BLOCK_STATUS
 226                                           * reply chunk */
 227 #define NBD_CMD_FLAG_FAST_ZERO  (1 << 4) /* fail if WRITE_ZEROES is not fast */
 228
 229 /* Supported request types */
 230 enum {
 231     NBD_CMD_READ = 0,
 232     NBD_CMD_WRITE = 1,
 233     NBD_CMD_DISC = 2,
 234     NBD_CMD_FLUSH = 3,
 235     NBD_CMD_TRIM = 4,
 236     NBD_CMD_CACHE = 5,
 237     NBD_CMD_WRITE_ZEROES = 6,
 238     NBD_CMD_BLOCK_STATUS = 7,
 239 };
 240
 241 #define NBD_DEFAULT_PORT        10809
 242
 243 /* Maximum size of a single READ/WRITE data buffer */
 244 #define NBD_MAX_BUFFER_SIZE (32 * 1024 * 1024)
 245
 246 /*
 247  * Maximum size of a protocol string (export name, metadata context name,
 248  * etc.).  Use malloc rather than stack allocation for storage of a
 249  * string.
 250  */
 251 #define NBD_MAX_STRING_SIZE 4096
 252
 253 /* Two types of reply structures */
 254 #define NBD_SIMPLE_REPLY_MAGIC      0x67446698
 255 #define NBD_STRUCTURED_REPLY_MAGIC  0x668e33ef
 256
 257 /* Structured reply flags */
 258 #define NBD_REPLY_FLAG_DONE          (1 << 0) /* This reply-chunk is last */
 259
 260 /* Structured reply types */
 261 #define NBD_REPLY_ERR(value)         ((1 << 15) | (value))
 262
 263 #define NBD_REPLY_TYPE_NONE          0
 264 #define NBD_REPLY_TYPE_OFFSET_DATA   1
 265 #define NBD_REPLY_TYPE_OFFSET_HOLE   2
 266 #define NBD_REPLY_TYPE_BLOCK_STATUS  5
 267 #define NBD_REPLY_TYPE_ERROR         NBD_REPLY_ERR(1)
 268 #define NBD_REPLY_TYPE_ERROR_OFFSET  NBD_REPLY_ERR(2)
 269
 270 /* Extent flags for base:allocation in NBD_REPLY_TYPE_BLOCK_STATUS */
 271 #define NBD_STATE_HOLE (1 << 0)
 272 #define NBD_STATE_ZERO (1 << 1)
 273
 274 /* Extent flags for qemu:dirty-bitmap in NBD_REPLY_TYPE_BLOCK_STATUS */
 275 #define NBD_STATE_DIRTY (1 << 0)
 276
 277 /* No flags needed for qemu:allocation-depth in NBD_REPLY_TYPE_BLOCK_STATUS */
 278
 279 static inline bool nbd_reply_type_is_error(int type)
 280 {
 281     return type & (1 << 15);
 282 }
 283
 284 /* NBD errors are based on errno numbers, so there is a 1:1 mapping,
 285  * but only a limited set of errno values is specified in the protocol.
 286  * Everything else is squashed to EINVAL.
 287  */
 288 #define NBD_SUCCESS    0
 289 #define NBD_EPERM      1
 290 #define NBD_EIO        5
 291 #define NBD_ENOMEM     12
 292 #define NBD_EINVAL     22
 293 #define NBD_ENOSPC     28
 294 #define NBD_EOVERFLOW  75
 295 #define NBD_ENOTSUP    95
 296 #define NBD_ESHUTDOWN  108
 297
 298 /* Details collected by NBD_OPT_EXPORT_NAME and NBD_OPT_GO */
 299 typedef struct NBDExportInfo {
 300     /* Set by client before nbd_receive_negotiate() */
 301     bool request_sizes;
 302     char *x_dirty_bitmap;
 303
 304     /* Set by client before nbd_receive_negotiate(), or by server results
 305      * during nbd_receive_export_list() */
 306     char *name; /* must be non-NULL */
 307
 308     /* In-out fields, set by client before nbd_receive_negotiate() and
 309      * updated by server results during nbd_receive_negotiate() */
 310     NBDMode mode; /* input maximum mode tolerated; output actual mode chosen */
 311     bool base_allocation; /* base:allocation context for NBD_CMD_BLOCK_STATUS */
 312
 313     /* Set by server results during nbd_receive_negotiate() and
 314      * nbd_receive_export_list() */
 315     uint64_t size;
 316     uint16_t flags;
 317     uint32_t min_block;
 318     uint32_t opt_block;
 319     uint32_t max_block;
 320
 321     uint32_t context_id;
 322
 323     /* Set by server results during nbd_receive_export_list() */
 324     char *description;
 325     int n_contexts;
 326     char **contexts;
 327 } NBDExportInfo;
 328
 329 int nbd_receive_negotiate(AioContext *aio_context, QIOChannel *ioc,
 330                           QCryptoTLSCreds *tlscreds,
 331                           const char *hostname, QIOChannel **outioc,
 332                           NBDExportInfo *info, Error **errp);
 333 void nbd_free_export_list(NBDExportInfo *info, int count);
 334 int nbd_receive_export_list(QIOChannel *ioc, QCryptoTLSCreds *tlscreds,
 335                             const char *hostname, NBDExportInfo **info,
 336                             Error **errp);
 337 int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info,
 338              Error **errp);
 339 int nbd_send_request(QIOChannel *ioc, NBDRequest *request);
 340 int coroutine_fn nbd_receive_reply(BlockDriverState *bs, QIOChannel *ioc,
 341                                    NBDReply *reply, Error **errp);
 342 int nbd_client(int fd);
 343 int nbd_disconnect(int fd);
 344 int nbd_errno_to_system_errno(int err);
 345
 346 void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk);
 347
 348 AioContext *nbd_export_aio_context(NBDExport *exp);
 349 NBDExport *nbd_export_find(const char *name);
 350
 351 void nbd_client_new(QIOChannelSocket *sioc,
 352                     QCryptoTLSCreds *tlscreds,
 353                     const char *tlsauthz,
 354                     void (*close_fn)(NBDClient *, bool));
 355 void nbd_client_get(NBDClient *client);
 356 void nbd_client_put(NBDClient *client);
 357
 358 void nbd_server_is_qemu_nbd(int max_connections);
 359 bool nbd_server_is_running(void);
 360 int nbd_server_max_connections(void);
 361 void nbd_server_start(SocketAddress *addr, const char *tls_creds,
 362                       const char *tls_authz, uint32_t max_connections,
 363                       Error **errp);
 364 void nbd_server_start_options(NbdServerOptions *arg, Error **errp);
 365
 366 /* nbd_read
 367  * Reads @size bytes from @ioc. Returns 0 on success.
 368  */
 369 static inline int nbd_read(QIOChannel *ioc, void *buffer, size_t size,
 370                            const char *desc, Error **errp)
 371 {
 372     ERRP_GUARD();
 373     int ret = qio_channel_read_all(ioc, buffer, size, errp) < 0 ? -EIO : 0;
 374
 375     if (ret < 0) {
 376         if (desc) {
 377             error_prepend(errp, "Failed to read %s: ", desc);
 378         }
 379         return ret;
 380     }
 381
 382     return 0;
 383 }
 384
 385 #define DEF_NBD_READ_N(bits)                                            \
 386 static inline int nbd_read##bits(QIOChannel *ioc,                       \
 387                                  uint##bits##_t *val,                   \
 388                                  const char *desc, Error **errp)        \
 389 {                                                                       \
 390     int ret = nbd_read(ioc, val, sizeof(*val), desc, errp);             \
 391     if (ret < 0) {                                                      \
 392         return ret;                                                     \
 393     }                                                                   \
 394     *val = be##bits##_to_cpu(*val);                                     \
 395     return 0;                                                           \
 396 }
 397
 398 DEF_NBD_READ_N(16) /* Defines nbd_read16(). */
 399 DEF_NBD_READ_N(32) /* Defines nbd_read32(). */
 400 DEF_NBD_READ_N(64) /* Defines nbd_read64(). */
 401
 402 #undef DEF_NBD_READ_N
 403
 404 static inline bool nbd_reply_is_simple(NBDReply *reply)
 405 {
 406     return reply->magic == NBD_SIMPLE_REPLY_MAGIC;
 407 }
 408
 409 static inline bool nbd_reply_is_structured(NBDReply *reply)
 410 {
 411     return reply->magic == NBD_STRUCTURED_REPLY_MAGIC;
 412 }
 413
 414 const char *nbd_reply_type_lookup(uint16_t type);
 415 const char *nbd_opt_lookup(uint32_t opt);
 416 const char *nbd_rep_lookup(uint32_t rep);
 417 const char *nbd_info_lookup(uint16_t info);
 418 const char *nbd_cmd_lookup(uint16_t info);
 419 const char *nbd_err_lookup(int err);
 420 const char *nbd_mode_lookup(NBDMode mode);
 421
 422 /* nbd/client-connection.c */
 423 void nbd_client_connection_enable_retry(NBDClientConnection *conn);
 424
 425 NBDClientConnection *nbd_client_connection_new(const SocketAddress *saddr,
 426                                                bool do_negotiation,
 427                                                const char *export_name,
 428                                                const char *x_dirty_bitmap,
 429                                                QCryptoTLSCreds *tlscreds,
 430                                                const char *tlshostname);
 431 void nbd_client_connection_release(NBDClientConnection *conn);
 432
 433 QIOChannel *coroutine_fn
 434 nbd_co_establish_connection(NBDClientConnection *conn, NBDExportInfo *info,
 435                             bool blocking, Error **errp);
 436
 437 void nbd_co_establish_connection_cancel(NBDClientConnection *conn);
 438
 439 #endif