1 /* 2 * Copyright (C) 2016-2017 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 24 #include "io/channel-socket.h" 25 #include "crypto/tlscreds.h" 26 27 /* Handshake phase structs - this struct is passed on the wire */ 28 29 struct NBDOption { 30 uint64_t magic; /* NBD_OPTS_MAGIC */ 31 uint32_t option; /* NBD_OPT_* */ 32 uint32_t length; 33 } QEMU_PACKED; 34 typedef struct NBDOption NBDOption; 35 36 struct NBDOptionReply { 37 uint64_t magic; /* NBD_REP_MAGIC */ 38 uint32_t option; /* NBD_OPT_* */ 39 uint32_t type; /* NBD_REP_* */ 40 uint32_t length; 41 } QEMU_PACKED; 42 typedef struct NBDOptionReply NBDOptionReply; 43 44 /* Transmission phase structs 45 * 46 * Note: these are _NOT_ the same as the network representation of an NBD 47 * request and reply! 48 */ 49 struct NBDRequest { 50 uint64_t handle; 51 uint64_t from; 52 uint32_t len; 53 uint16_t flags; /* NBD_CMD_FLAG_* */ 54 uint16_t type; /* NBD_CMD_* */ 55 }; 56 typedef struct NBDRequest NBDRequest; 57 58 typedef struct NBDSimpleReply { 59 uint32_t magic; /* NBD_SIMPLE_REPLY_MAGIC */ 60 uint32_t error; 61 uint64_t handle; 62 } QEMU_PACKED NBDSimpleReply; 63 64 /* Header of all structured replies */ 65 typedef struct NBDStructuredReplyChunk { 66 uint32_t magic; /* NBD_STRUCTURED_REPLY_MAGIC */ 67 uint16_t flags; /* combination of NBD_REPLY_FLAG_* */ 68 uint16_t type; /* NBD_REPLY_TYPE_* */ 69 uint64_t handle; /* request handle */ 70 uint32_t length; /* length of payload */ 71 } QEMU_PACKED NBDStructuredReplyChunk; 72 73 typedef union NBDReply { 74 NBDSimpleReply simple; 75 NBDStructuredReplyChunk structured; 76 struct { 77 /* @magic and @handle fields have the same offset and size both in 78 * simple reply and structured reply chunk, so let them be accessible 79 * without ".simple." or ".structured." specification 80 */ 81 uint32_t magic; 82 uint32_t _skip; 83 uint64_t handle; 84 } QEMU_PACKED; 85 } NBDReply; 86 87 /* Header of chunk for NBD_REPLY_TYPE_OFFSET_DATA */ 88 typedef struct NBDStructuredReadData { 89 NBDStructuredReplyChunk h; /* h.length >= 9 */ 90 uint64_t offset; 91 /* At least one byte of data payload follows, calculated from h.length */ 92 } QEMU_PACKED NBDStructuredReadData; 93 94 /* Complete chunk for NBD_REPLY_TYPE_OFFSET_HOLE */ 95 typedef struct NBDStructuredReadHole { 96 NBDStructuredReplyChunk h; /* h.length == 12 */ 97 uint64_t offset; 98 uint32_t length; 99 } QEMU_PACKED NBDStructuredReadHole; 100 101 /* Header of all NBD_REPLY_TYPE_ERROR* errors */ 102 typedef struct NBDStructuredError { 103 NBDStructuredReplyChunk h; /* h.length >= 6 */ 104 uint32_t error; 105 uint16_t message_length; 106 } QEMU_PACKED NBDStructuredError; 107 108 /* Transmission (export) flags: sent from server to client during handshake, 109 but describe what will happen during transmission */ 110 #define NBD_FLAG_HAS_FLAGS (1 << 0) /* Flags are there */ 111 #define NBD_FLAG_READ_ONLY (1 << 1) /* Device is read-only */ 112 #define NBD_FLAG_SEND_FLUSH (1 << 2) /* Send FLUSH */ 113 #define NBD_FLAG_SEND_FUA (1 << 3) /* Send FUA (Force Unit Access) */ 114 #define NBD_FLAG_ROTATIONAL (1 << 4) /* Use elevator algorithm - 115 rotational media */ 116 #define NBD_FLAG_SEND_TRIM (1 << 5) /* Send TRIM (discard) */ 117 #define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6) /* Send WRITE_ZEROES */ 118 #define NBD_FLAG_SEND_DF (1 << 7) /* Send DF (Do not Fragment) */ 119 120 /* New-style handshake (global) flags, sent from server to client, and 121 control what will happen during handshake phase. */ 122 #define NBD_FLAG_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */ 123 #define NBD_FLAG_NO_ZEROES (1 << 1) /* End handshake without zeroes. */ 124 125 /* New-style client flags, sent from client to server to control what happens 126 during handshake phase. */ 127 #define NBD_FLAG_C_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */ 128 #define NBD_FLAG_C_NO_ZEROES (1 << 1) /* End handshake without zeroes. */ 129 130 /* Option requests. */ 131 #define NBD_OPT_EXPORT_NAME (1) 132 #define NBD_OPT_ABORT (2) 133 #define NBD_OPT_LIST (3) 134 /* #define NBD_OPT_PEEK_EXPORT (4) not in use */ 135 #define NBD_OPT_STARTTLS (5) 136 #define NBD_OPT_INFO (6) 137 #define NBD_OPT_GO (7) 138 #define NBD_OPT_STRUCTURED_REPLY (8) 139 140 /* Option reply types. */ 141 #define NBD_REP_ERR(value) ((UINT32_C(1) << 31) | (value)) 142 143 #define NBD_REP_ACK (1) /* Data sending finished. */ 144 #define NBD_REP_SERVER (2) /* Export description. */ 145 #define NBD_REP_INFO (3) /* NBD_OPT_INFO/GO. */ 146 147 #define NBD_REP_ERR_UNSUP NBD_REP_ERR(1) /* Unknown option */ 148 #define NBD_REP_ERR_POLICY NBD_REP_ERR(2) /* Server denied */ 149 #define NBD_REP_ERR_INVALID NBD_REP_ERR(3) /* Invalid length */ 150 #define NBD_REP_ERR_PLATFORM NBD_REP_ERR(4) /* Not compiled in */ 151 #define NBD_REP_ERR_TLS_REQD NBD_REP_ERR(5) /* TLS required */ 152 #define NBD_REP_ERR_UNKNOWN NBD_REP_ERR(6) /* Export unknown */ 153 #define NBD_REP_ERR_SHUTDOWN NBD_REP_ERR(7) /* Server shutting down */ 154 #define NBD_REP_ERR_BLOCK_SIZE_REQD NBD_REP_ERR(8) /* Need INFO_BLOCK_SIZE */ 155 156 /* Info types, used during NBD_REP_INFO */ 157 #define NBD_INFO_EXPORT 0 158 #define NBD_INFO_NAME 1 159 #define NBD_INFO_DESCRIPTION 2 160 #define NBD_INFO_BLOCK_SIZE 3 161 162 /* Request flags, sent from client to server during transmission phase */ 163 #define NBD_CMD_FLAG_FUA (1 << 0) /* 'force unit access' during write */ 164 #define NBD_CMD_FLAG_NO_HOLE (1 << 1) /* don't punch hole on zero run */ 165 #define NBD_CMD_FLAG_DF (1 << 2) /* don't fragment structured read */ 166 167 /* Supported request types */ 168 enum { 169 NBD_CMD_READ = 0, 170 NBD_CMD_WRITE = 1, 171 NBD_CMD_DISC = 2, 172 NBD_CMD_FLUSH = 3, 173 NBD_CMD_TRIM = 4, 174 /* 5 reserved for failed experiment NBD_CMD_CACHE */ 175 NBD_CMD_WRITE_ZEROES = 6, 176 }; 177 178 #define NBD_DEFAULT_PORT 10809 179 180 /* Maximum size of a single READ/WRITE data buffer */ 181 #define NBD_MAX_BUFFER_SIZE (32 * 1024 * 1024) 182 183 /* Maximum size of an export name. The NBD spec requires 256 and 184 * suggests that servers support up to 4096, but we stick to only the 185 * required size so that we can stack-allocate the names, and because 186 * going larger would require an audit of more code to make sure we 187 * aren't overflowing some other buffer. */ 188 #define NBD_MAX_NAME_SIZE 256 189 190 /* Two types of reply structures */ 191 #define NBD_SIMPLE_REPLY_MAGIC 0x67446698 192 #define NBD_STRUCTURED_REPLY_MAGIC 0x668e33ef 193 194 /* Structured reply flags */ 195 #define NBD_REPLY_FLAG_DONE (1 << 0) /* This reply-chunk is last */ 196 197 /* Structured reply types */ 198 #define NBD_REPLY_ERR(value) ((1 << 15) | (value)) 199 200 #define NBD_REPLY_TYPE_NONE 0 201 #define NBD_REPLY_TYPE_OFFSET_DATA 1 202 #define NBD_REPLY_TYPE_OFFSET_HOLE 2 203 #define NBD_REPLY_TYPE_ERROR NBD_REPLY_ERR(1) 204 #define NBD_REPLY_TYPE_ERROR_OFFSET NBD_REPLY_ERR(2) 205 206 static inline bool nbd_reply_type_is_error(int type) 207 { 208 return type & (1 << 15); 209 } 210 211 /* NBD errors are based on errno numbers, so there is a 1:1 mapping, 212 * but only a limited set of errno values is specified in the protocol. 213 * Everything else is squashed to EINVAL. 214 */ 215 #define NBD_SUCCESS 0 216 #define NBD_EPERM 1 217 #define NBD_EIO 5 218 #define NBD_ENOMEM 12 219 #define NBD_EINVAL 22 220 #define NBD_ENOSPC 28 221 #define NBD_EOVERFLOW 75 222 #define NBD_ESHUTDOWN 108 223 224 /* Details collected by NBD_OPT_EXPORT_NAME and NBD_OPT_GO */ 225 struct NBDExportInfo { 226 /* Set by client before nbd_receive_negotiate() */ 227 bool request_sizes; 228 229 /* In-out fields, set by client before nbd_receive_negotiate() and 230 * updated by server results during nbd_receive_negotiate() */ 231 bool structured_reply; 232 233 /* Set by server results during nbd_receive_negotiate() */ 234 uint64_t size; 235 uint16_t flags; 236 uint32_t min_block; 237 uint32_t opt_block; 238 uint32_t max_block; 239 }; 240 typedef struct NBDExportInfo NBDExportInfo; 241 242 int nbd_receive_negotiate(QIOChannel *ioc, const char *name, 243 QCryptoTLSCreds *tlscreds, const char *hostname, 244 QIOChannel **outioc, NBDExportInfo *info, 245 Error **errp); 246 int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info, 247 Error **errp); 248 int nbd_send_request(QIOChannel *ioc, NBDRequest *request); 249 int nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp); 250 int nbd_client(int fd); 251 int nbd_disconnect(int fd); 252 int nbd_errno_to_system_errno(int err); 253 254 typedef struct NBDExport NBDExport; 255 typedef struct NBDClient NBDClient; 256 257 NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset, off_t size, 258 uint16_t nbdflags, void (*close)(NBDExport *), 259 bool writethrough, BlockBackend *on_eject_blk, 260 Error **errp); 261 void nbd_export_close(NBDExport *exp); 262 void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp); 263 void nbd_export_get(NBDExport *exp); 264 void nbd_export_put(NBDExport *exp); 265 266 BlockBackend *nbd_export_get_blockdev(NBDExport *exp); 267 268 NBDExport *nbd_export_find(const char *name); 269 void nbd_export_set_name(NBDExport *exp, const char *name); 270 void nbd_export_set_description(NBDExport *exp, const char *description); 271 void nbd_export_close_all(void); 272 273 void nbd_client_new(NBDExport *exp, 274 QIOChannelSocket *sioc, 275 QCryptoTLSCreds *tlscreds, 276 const char *tlsaclname, 277 void (*close_fn)(NBDClient *, bool)); 278 void nbd_client_get(NBDClient *client); 279 void nbd_client_put(NBDClient *client); 280 281 void nbd_server_start(SocketAddress *addr, const char *tls_creds, 282 Error **errp); 283 284 285 /* nbd_read 286 * Reads @size bytes from @ioc. Returns 0 on success. 287 */ 288 static inline int nbd_read(QIOChannel *ioc, void *buffer, size_t size, 289 Error **errp) 290 { 291 return qio_channel_read_all(ioc, buffer, size, errp) < 0 ? -EIO : 0; 292 } 293 294 static inline bool nbd_reply_is_simple(NBDReply *reply) 295 { 296 return reply->magic == NBD_SIMPLE_REPLY_MAGIC; 297 } 298 299 static inline bool nbd_reply_is_structured(NBDReply *reply) 300 { 301 return reply->magic == NBD_STRUCTURED_REPLY_MAGIC; 302 } 303 304 const char *nbd_reply_type_lookup(uint16_t type); 305 306 #endif 307