nbd.h (16069B)
1 /* 2 * Copyright (C) 2016-2022 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(int max_connections); 348 bool nbd_server_is_running(void); 349 int nbd_server_max_connections(void); 350 void nbd_server_start(SocketAddress *addr, const char *tls_creds, 351 const char *tls_authz, uint32_t max_connections, 352 Error **errp); 353 void nbd_server_start_options(NbdServerOptions *arg, Error **errp); 354 355 /* nbd_read 356 * Reads @size bytes from @ioc. Returns 0 on success. 357 */ 358 static inline int nbd_read(QIOChannel *ioc, void *buffer, size_t size, 359 const char *desc, Error **errp) 360 { 361 ERRP_GUARD(); 362 int ret = qio_channel_read_all(ioc, buffer, size, errp) < 0 ? -EIO : 0; 363 364 if (ret < 0) { 365 if (desc) { 366 error_prepend(errp, "Failed to read %s: ", desc); 367 } 368 return ret; 369 } 370 371 return 0; 372 } 373 374 #define DEF_NBD_READ_N(bits) \ 375 static inline int nbd_read##bits(QIOChannel *ioc, \ 376 uint##bits##_t *val, \ 377 const char *desc, Error **errp) \ 378 { \ 379 int ret = nbd_read(ioc, val, sizeof(*val), desc, errp); \ 380 if (ret < 0) { \ 381 return ret; \ 382 } \ 383 *val = be##bits##_to_cpu(*val); \ 384 return 0; \ 385 } 386 387 DEF_NBD_READ_N(16) /* Defines nbd_read16(). */ 388 DEF_NBD_READ_N(32) /* Defines nbd_read32(). */ 389 DEF_NBD_READ_N(64) /* Defines nbd_read64(). */ 390 391 #undef DEF_NBD_READ_N 392 393 static inline bool nbd_reply_is_simple(NBDReply *reply) 394 { 395 return reply->magic == NBD_SIMPLE_REPLY_MAGIC; 396 } 397 398 static inline bool nbd_reply_is_structured(NBDReply *reply) 399 { 400 return reply->magic == NBD_STRUCTURED_REPLY_MAGIC; 401 } 402 403 const char *nbd_reply_type_lookup(uint16_t type); 404 const char *nbd_opt_lookup(uint32_t opt); 405 const char *nbd_rep_lookup(uint32_t rep); 406 const char *nbd_info_lookup(uint16_t info); 407 const char *nbd_cmd_lookup(uint16_t info); 408 const char *nbd_err_lookup(int err); 409 410 /* nbd/client-connection.c */ 411 typedef struct NBDClientConnection NBDClientConnection; 412 413 void nbd_client_connection_enable_retry(NBDClientConnection *conn); 414 415 NBDClientConnection *nbd_client_connection_new(const SocketAddress *saddr, 416 bool do_negotiation, 417 const char *export_name, 418 const char *x_dirty_bitmap, 419 QCryptoTLSCreds *tlscreds, 420 const char *tlshostname); 421 void nbd_client_connection_release(NBDClientConnection *conn); 422 423 QIOChannel *coroutine_fn 424 nbd_co_establish_connection(NBDClientConnection *conn, NBDExportInfo *info, 425 bool blocking, Error **errp); 426 427 void nbd_co_establish_connection_cancel(NBDClientConnection *conn); 428 429 #endif