nbd.h (15963B)
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 28extern const BlockExportDriver blk_exp_nbd; 29 30/* Handshake phase structs - this struct is passed on the wire */ 31 32struct NBDOption { 33 uint64_t magic; /* NBD_OPTS_MAGIC */ 34 uint32_t option; /* NBD_OPT_* */ 35 uint32_t length; 36} QEMU_PACKED; 37typedef struct NBDOption NBDOption; 38 39struct 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; 45typedef struct NBDOptionReply NBDOptionReply; 46 47typedef 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 */ 58struct 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}; 65typedef struct NBDRequest NBDRequest; 66 67typedef 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 */ 74typedef 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 82typedef 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 */ 97typedef 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 */ 104typedef 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 */ 111typedef 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 */ 118typedef 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 */ 125typedef 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 */ 132enum { 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 */ 215enum { 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 264static 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 */ 284struct 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}; 313typedef struct NBDExportInfo NBDExportInfo; 314 315int nbd_receive_negotiate(AioContext *aio_context, QIOChannel *ioc, 316 QCryptoTLSCreds *tlscreds, 317 const char *hostname, QIOChannel **outioc, 318 NBDExportInfo *info, Error **errp); 319void nbd_free_export_list(NBDExportInfo *info, int count); 320int nbd_receive_export_list(QIOChannel *ioc, QCryptoTLSCreds *tlscreds, 321 const char *hostname, NBDExportInfo **info, 322 Error **errp); 323int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info, 324 Error **errp); 325int nbd_send_request(QIOChannel *ioc, NBDRequest *request); 326int coroutine_fn nbd_receive_reply(BlockDriverState *bs, QIOChannel *ioc, 327 NBDReply *reply, Error **errp); 328int nbd_client(int fd); 329int nbd_disconnect(int fd); 330int nbd_errno_to_system_errno(int err); 331 332typedef struct NBDExport NBDExport; 333typedef struct NBDClient NBDClient; 334 335void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk); 336 337AioContext *nbd_export_aio_context(NBDExport *exp); 338NBDExport *nbd_export_find(const char *name); 339 340void nbd_client_new(QIOChannelSocket *sioc, 341 QCryptoTLSCreds *tlscreds, 342 const char *tlsauthz, 343 void (*close_fn)(NBDClient *, bool)); 344void nbd_client_get(NBDClient *client); 345void nbd_client_put(NBDClient *client); 346 347void nbd_server_is_qemu_nbd(bool value); 348bool nbd_server_is_running(void); 349void nbd_server_start(SocketAddress *addr, const char *tls_creds, 350 const char *tls_authz, uint32_t max_connections, 351 Error **errp); 352void nbd_server_start_options(NbdServerOptions *arg, Error **errp); 353 354/* nbd_read 355 * Reads @size bytes from @ioc. Returns 0 on success. 356 */ 357static 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) \ 374static 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 386DEF_NBD_READ_N(16) /* Defines nbd_read16(). */ 387DEF_NBD_READ_N(32) /* Defines nbd_read32(). */ 388DEF_NBD_READ_N(64) /* Defines nbd_read64(). */ 389 390#undef DEF_NBD_READ_N 391 392static inline bool nbd_reply_is_simple(NBDReply *reply) 393{ 394 return reply->magic == NBD_SIMPLE_REPLY_MAGIC; 395} 396 397static inline bool nbd_reply_is_structured(NBDReply *reply) 398{ 399 return reply->magic == NBD_STRUCTURED_REPLY_MAGIC; 400} 401 402const char *nbd_reply_type_lookup(uint16_t type); 403const char *nbd_opt_lookup(uint32_t opt); 404const char *nbd_rep_lookup(uint32_t rep); 405const char *nbd_info_lookup(uint16_t info); 406const char *nbd_cmd_lookup(uint16_t info); 407const char *nbd_err_lookup(int err); 408 409/* nbd/client-connection.c */ 410typedef struct NBDClientConnection NBDClientConnection; 411 412void nbd_client_connection_enable_retry(NBDClientConnection *conn); 413 414NBDClientConnection *nbd_client_connection_new(const SocketAddress *saddr, 415 bool do_negotiation, 416 const char *export_name, 417 const char *x_dirty_bitmap, 418 QCryptoTLSCreds *tlscreds); 419void nbd_client_connection_release(NBDClientConnection *conn); 420 421QIOChannel *coroutine_fn 422nbd_co_establish_connection(NBDClientConnection *conn, NBDExportInfo *info, 423 bool blocking, Error **errp); 424 425void coroutine_fn nbd_co_establish_connection_cancel(NBDClientConnection *conn); 426 427#endif