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 "qemu-common.h" 25 #include "qemu/option.h" 26 #include "io/channel-socket.h" 27 #include "crypto/tlscreds.h" 28 29 /* Handshake phase structs - this struct is passed on the wire */ 30 31 struct nbd_option { 32 uint64_t magic; /* NBD_OPTS_MAGIC */ 33 uint32_t option; /* NBD_OPT_* */ 34 uint32_t length; 35 } QEMU_PACKED; 36 typedef struct nbd_option nbd_option; 37 38 struct nbd_opt_reply { 39 uint64_t magic; /* NBD_REP_MAGIC */ 40 uint32_t option; /* NBD_OPT_* */ 41 uint32_t type; /* NBD_REP_* */ 42 uint32_t length; 43 } QEMU_PACKED; 44 typedef struct nbd_opt_reply nbd_opt_reply; 45 46 /* Transmission phase structs 47 * 48 * Note: these are _NOT_ the same as the network representation of an NBD 49 * request and reply! 50 */ 51 struct NBDRequest { 52 uint64_t handle; 53 uint64_t from; 54 uint32_t len; 55 uint16_t flags; /* NBD_CMD_FLAG_* */ 56 uint16_t type; /* NBD_CMD_* */ 57 }; 58 typedef struct NBDRequest NBDRequest; 59 60 typedef struct NBDSimpleReply { 61 uint32_t magic; /* NBD_SIMPLE_REPLY_MAGIC */ 62 uint32_t error; 63 uint64_t handle; 64 } QEMU_PACKED NBDSimpleReply; 65 66 /* Header of all structured replies */ 67 typedef struct NBDStructuredReplyChunk { 68 uint32_t magic; /* NBD_STRUCTURED_REPLY_MAGIC */ 69 uint16_t flags; /* combination of NBD_REPLY_FLAG_* */ 70 uint16_t type; /* NBD_REPLY_TYPE_* */ 71 uint64_t handle; /* request handle */ 72 uint32_t length; /* length of payload */ 73 } QEMU_PACKED NBDStructuredReplyChunk; 74 75 typedef union NBDReply { 76 NBDSimpleReply simple; 77 NBDStructuredReplyChunk structured; 78 struct { 79 /* @magic and @handle fields have the same offset and size both in 80 * simple reply and structured reply chunk, so let them be accessible 81 * without ".simple." or ".structured." specification 82 */ 83 uint32_t magic; 84 uint32_t _skip; 85 uint64_t handle; 86 } QEMU_PACKED; 87 } NBDReply; 88 89 /* Header of chunk for NBD_REPLY_TYPE_OFFSET_DATA */ 90 typedef struct NBDStructuredReadData { 91 NBDStructuredReplyChunk h; /* h.length >= 9 */ 92 uint64_t offset; 93 /* At least one byte of data payload follows, calculated from h.length */ 94 } QEMU_PACKED NBDStructuredReadData; 95 96 /* Complete chunk for NBD_REPLY_TYPE_OFFSET_HOLE */ 97 typedef struct NBDStructuredReadHole { 98 NBDStructuredReplyChunk h; /* h.length == 12 */ 99 uint64_t offset; 100 uint32_t length; 101 } QEMU_PACKED NBDStructuredReadHole; 102 103 /* Header of all NBD_REPLY_TYPE_ERROR* errors */ 104 typedef struct NBDStructuredError { 105 NBDStructuredReplyChunk h; /* h.length >= 6 */ 106 uint32_t error; 107 uint16_t message_length; 108 } QEMU_PACKED NBDStructuredError; 109 110 /* Transmission (export) flags: sent from server to client during handshake, 111 but describe what will happen during transmission */ 112 #define NBD_FLAG_HAS_FLAGS (1 << 0) /* Flags are there */ 113 #define NBD_FLAG_READ_ONLY (1 << 1) /* Device is read-only */ 114 #define NBD_FLAG_SEND_FLUSH (1 << 2) /* Send FLUSH */ 115 #define NBD_FLAG_SEND_FUA (1 << 3) /* Send FUA (Force Unit Access) */ 116 #define NBD_FLAG_ROTATIONAL (1 << 4) /* Use elevator algorithm - 117 rotational media */ 118 #define NBD_FLAG_SEND_TRIM (1 << 5) /* Send TRIM (discard) */ 119 #define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6) /* Send WRITE_ZEROES */ 120 #define NBD_FLAG_SEND_DF (1 << 7) /* Send DF (Do not Fragment) */ 121 122 /* New-style handshake (global) flags, sent from server to client, and 123 control what will happen during handshake phase. */ 124 #define NBD_FLAG_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */ 125 #define NBD_FLAG_NO_ZEROES (1 << 1) /* End handshake without zeroes. */ 126 127 /* New-style client flags, sent from client to server to control what happens 128 during handshake phase. */ 129 #define NBD_FLAG_C_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */ 130 #define NBD_FLAG_C_NO_ZEROES (1 << 1) /* End handshake without zeroes. */ 131 132 /* Option requests. */ 133 #define NBD_OPT_EXPORT_NAME (1) 134 #define NBD_OPT_ABORT (2) 135 #define NBD_OPT_LIST (3) 136 /* #define NBD_OPT_PEEK_EXPORT (4) not in use */ 137 #define NBD_OPT_STARTTLS (5) 138 #define NBD_OPT_INFO (6) 139 #define NBD_OPT_GO (7) 140 #define NBD_OPT_STRUCTURED_REPLY (8) 141 142 /* Option reply types. */ 143 #define NBD_REP_ERR(value) ((UINT32_C(1) << 31) | (value)) 144 145 #define NBD_REP_ACK (1) /* Data sending finished. */ 146 #define NBD_REP_SERVER (2) /* Export description. */ 147 #define NBD_REP_INFO (3) /* NBD_OPT_INFO/GO. */ 148 149 #define NBD_REP_ERR_UNSUP NBD_REP_ERR(1) /* Unknown option */ 150 #define NBD_REP_ERR_POLICY NBD_REP_ERR(2) /* Server denied */ 151 #define NBD_REP_ERR_INVALID NBD_REP_ERR(3) /* Invalid length */ 152 #define NBD_REP_ERR_PLATFORM NBD_REP_ERR(4) /* Not compiled in */ 153 #define NBD_REP_ERR_TLS_REQD NBD_REP_ERR(5) /* TLS required */ 154 #define NBD_REP_ERR_UNKNOWN NBD_REP_ERR(6) /* Export unknown */ 155 #define NBD_REP_ERR_SHUTDOWN NBD_REP_ERR(7) /* Server shutting down */ 156 #define NBD_REP_ERR_BLOCK_SIZE_REQD NBD_REP_ERR(8) /* Need INFO_BLOCK_SIZE */ 157 158 /* Info types, used during NBD_REP_INFO */ 159 #define NBD_INFO_EXPORT 0 160 #define NBD_INFO_NAME 1 161 #define NBD_INFO_DESCRIPTION 2 162 #define NBD_INFO_BLOCK_SIZE 3 163 164 /* Request flags, sent from client to server during transmission phase */ 165 #define NBD_CMD_FLAG_FUA (1 << 0) /* 'force unit access' during write */ 166 #define NBD_CMD_FLAG_NO_HOLE (1 << 1) /* don't punch hole on zero run */ 167 #define NBD_CMD_FLAG_DF (1 << 2) /* don't fragment structured read */ 168 169 /* Supported request types */ 170 enum { 171 NBD_CMD_READ = 0, 172 NBD_CMD_WRITE = 1, 173 NBD_CMD_DISC = 2, 174 NBD_CMD_FLUSH = 3, 175 NBD_CMD_TRIM = 4, 176 /* 5 reserved for failed experiment NBD_CMD_CACHE */ 177 NBD_CMD_WRITE_ZEROES = 6, 178 }; 179 180 #define NBD_DEFAULT_PORT 10809 181 182 /* Maximum size of a single READ/WRITE data buffer */ 183 #define NBD_MAX_BUFFER_SIZE (32 * 1024 * 1024) 184 185 /* Maximum size of an export name. The NBD spec requires 256 and 186 * suggests that servers support up to 4096, but we stick to only the 187 * required size so that we can stack-allocate the names, and because 188 * going larger would require an audit of more code to make sure we 189 * aren't overflowing some other buffer. */ 190 #define NBD_MAX_NAME_SIZE 256 191 192 /* Two types of reply structures */ 193 #define NBD_SIMPLE_REPLY_MAGIC 0x67446698 194 #define NBD_STRUCTURED_REPLY_MAGIC 0x668e33ef 195 196 /* Structured reply flags */ 197 #define NBD_REPLY_FLAG_DONE (1 << 0) /* This reply-chunk is last */ 198 199 /* Structured reply types */ 200 #define NBD_REPLY_ERR(value) ((1 << 15) | (value)) 201 202 #define NBD_REPLY_TYPE_NONE 0 203 #define NBD_REPLY_TYPE_OFFSET_DATA 1 204 #define NBD_REPLY_TYPE_OFFSET_HOLE 2 205 #define NBD_REPLY_TYPE_ERROR NBD_REPLY_ERR(1) 206 #define NBD_REPLY_TYPE_ERROR_OFFSET NBD_REPLY_ERR(2) 207 208 static inline bool nbd_reply_type_is_error(int type) 209 { 210 return type & (1 << 15); 211 } 212 213 /* NBD errors are based on errno numbers, so there is a 1:1 mapping, 214 * but only a limited set of errno values is specified in the protocol. 215 * Everything else is squashed to EINVAL. 216 */ 217 #define NBD_SUCCESS 0 218 #define NBD_EPERM 1 219 #define NBD_EIO 5 220 #define NBD_ENOMEM 12 221 #define NBD_EINVAL 22 222 #define NBD_ENOSPC 28 223 #define NBD_EOVERFLOW 75 224 #define NBD_ESHUTDOWN 108 225 226 /* Details collected by NBD_OPT_EXPORT_NAME and NBD_OPT_GO */ 227 struct NBDExportInfo { 228 /* Set by client before nbd_receive_negotiate() */ 229 bool request_sizes; 230 231 /* In-out fields, set by client before nbd_receive_negotiate() and 232 * updated by server results during nbd_receive_negotiate() */ 233 bool structured_reply; 234 235 /* Set by server results during nbd_receive_negotiate() */ 236 uint64_t size; 237 uint16_t flags; 238 uint32_t min_block; 239 uint32_t opt_block; 240 uint32_t max_block; 241 }; 242 typedef struct NBDExportInfo NBDExportInfo; 243 244 int nbd_receive_negotiate(QIOChannel *ioc, const char *name, 245 QCryptoTLSCreds *tlscreds, const char *hostname, 246 QIOChannel **outioc, NBDExportInfo *info, 247 Error **errp); 248 int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info, 249 Error **errp); 250 int nbd_send_request(QIOChannel *ioc, NBDRequest *request); 251 int nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp); 252 int nbd_client(int fd); 253 int nbd_disconnect(int fd); 254 int nbd_errno_to_system_errno(int err); 255 256 typedef struct NBDExport NBDExport; 257 typedef struct NBDClient NBDClient; 258 259 NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset, off_t size, 260 uint16_t nbdflags, void (*close)(NBDExport *), 261 bool writethrough, BlockBackend *on_eject_blk, 262 Error **errp); 263 void nbd_export_close(NBDExport *exp); 264 void nbd_export_get(NBDExport *exp); 265 void nbd_export_put(NBDExport *exp); 266 267 BlockBackend *nbd_export_get_blockdev(NBDExport *exp); 268 269 NBDExport *nbd_export_find(const char *name); 270 void nbd_export_set_name(NBDExport *exp, const char *name); 271 void nbd_export_set_description(NBDExport *exp, const char *description); 272 void nbd_export_close_all(void); 273 274 void nbd_client_new(NBDExport *exp, 275 QIOChannelSocket *sioc, 276 QCryptoTLSCreds *tlscreds, 277 const char *tlsaclname, 278 void (*close_fn)(NBDClient *, bool)); 279 void nbd_client_get(NBDClient *client); 280 void nbd_client_put(NBDClient *client); 281 282 void nbd_server_start(SocketAddress *addr, const char *tls_creds, 283 Error **errp); 284 285 286 /* nbd_read 287 * Reads @size bytes from @ioc. Returns 0 on success. 288 */ 289 static inline int nbd_read(QIOChannel *ioc, void *buffer, size_t size, 290 Error **errp) 291 { 292 return qio_channel_read_all(ioc, buffer, size, errp) < 0 ? -EIO : 0; 293 } 294 295 static inline bool nbd_reply_is_simple(NBDReply *reply) 296 { 297 return reply->magic == NBD_SIMPLE_REPLY_MAGIC; 298 } 299 300 static inline bool nbd_reply_is_structured(NBDReply *reply) 301 { 302 return reply->magic == NBD_STRUCTURED_REPLY_MAGIC; 303 } 304 305 const char *nbd_reply_type_lookup(uint16_t type); 306 307 #endif 308