LXR qemu/include/block/nbd.h

   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#include "qapi/qapi-types-block.h"
  24#include "io/channel-socket.h"
  25#include "crypto/tlscreds.h"
  26
  27/* Handshake phase structs - this struct is passed on the wire */
  28
  29struct NBDOption {
  30    uint64_t magic; /* NBD_OPTS_MAGIC */
  31    uint32_t option; /* NBD_OPT_* */
  32    uint32_t length;
  33} QEMU_PACKED;
  34typedef struct NBDOption NBDOption;
  35
  36struct 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;
  42typedef struct NBDOptionReply NBDOptionReply;
  43
  44typedef struct NBDOptionReplyMetaContext {
  45    NBDOptionReply h; /* h.type = NBD_REP_META_CONTEXT, h.length > 4 */
  46    uint32_t context_id;
  47    /* meta context name follows */
  48} QEMU_PACKED NBDOptionReplyMetaContext;
  49
  50/* Transmission phase structs
  51 *
  52 * Note: these are _NOT_ the same as the network representation of an NBD
  53 * request and reply!
  54 */
  55struct NBDRequest {
  56    uint64_t handle;
  57    uint64_t from;
  58    uint32_t len;
  59    uint16_t flags; /* NBD_CMD_FLAG_* */
  60    uint16_t type; /* NBD_CMD_* */
  61};
  62typedef struct NBDRequest NBDRequest;
  63
  64typedef struct NBDSimpleReply {
  65    uint32_t magic;  /* NBD_SIMPLE_REPLY_MAGIC */
  66    uint32_t error;
  67    uint64_t handle;
  68} QEMU_PACKED NBDSimpleReply;
  69
  70/* Header of all structured replies */
  71typedef struct NBDStructuredReplyChunk {
  72    uint32_t magic;  /* NBD_STRUCTURED_REPLY_MAGIC */
  73    uint16_t flags;  /* combination of NBD_REPLY_FLAG_* */
  74    uint16_t type;   /* NBD_REPLY_TYPE_* */
  75    uint64_t handle; /* request handle */
  76    uint32_t length; /* length of payload */
  77} QEMU_PACKED NBDStructuredReplyChunk;
  78
  79typedef union NBDReply {
  80    NBDSimpleReply simple;
  81    NBDStructuredReplyChunk structured;
  82    struct {
  83        /* @magic and @handle fields have the same offset and size both in
  84         * simple reply and structured reply chunk, so let them be accessible
  85         * without ".simple." or ".structured." specification
  86         */
  87        uint32_t magic;
  88        uint32_t _skip;
  89        uint64_t handle;
  90    } QEMU_PACKED;
  91} NBDReply;
  92
  93/* Header of chunk for NBD_REPLY_TYPE_OFFSET_DATA */
  94typedef struct NBDStructuredReadData {
  95    NBDStructuredReplyChunk h; /* h.length >= 9 */
  96    uint64_t offset;
  97    /* At least one byte of data payload follows, calculated from h.length */
  98} QEMU_PACKED NBDStructuredReadData;
  99
 100/* Complete chunk for NBD_REPLY_TYPE_OFFSET_HOLE */
 101typedef struct NBDStructuredReadHole {
 102    NBDStructuredReplyChunk h; /* h.length == 12 */
 103    uint64_t offset;
 104    uint32_t length;
 105} QEMU_PACKED NBDStructuredReadHole;
 106
 107/* Header of all NBD_REPLY_TYPE_ERROR* errors */
 108typedef struct NBDStructuredError {
 109    NBDStructuredReplyChunk h; /* h.length >= 6 */
 110    uint32_t error;
 111    uint16_t message_length;
 112} QEMU_PACKED NBDStructuredError;
 113
 114/* Header of NBD_REPLY_TYPE_BLOCK_STATUS */
 115typedef struct NBDStructuredMeta {
 116    NBDStructuredReplyChunk h; /* h.length >= 12 (at least one extent) */
 117    uint32_t context_id;
 118    /* extents follows */
 119} QEMU_PACKED NBDStructuredMeta;
 120
 121/* Extent chunk for NBD_REPLY_TYPE_BLOCK_STATUS */
 122typedef struct NBDExtent {
 123    uint32_t length;
 124    uint32_t flags; /* NBD_STATE_* */
 125} QEMU_PACKED NBDExtent;
 126
 127/* Transmission (export) flags: sent from server to client during handshake,
 128   but describe what will happen during transmission */
 129#define NBD_FLAG_HAS_FLAGS         (1 << 0) /* Flags are there */
 130#define NBD_FLAG_READ_ONLY         (1 << 1) /* Device is read-only */
 131#define NBD_FLAG_SEND_FLUSH        (1 << 2) /* Send FLUSH */
 132#define NBD_FLAG_SEND_FUA          (1 << 3) /* Send FUA (Force Unit Access) */
 133#define NBD_FLAG_ROTATIONAL        (1 << 4) /* Use elevator algorithm -
 134                                               rotational media */
 135#define NBD_FLAG_SEND_TRIM         (1 << 5) /* Send TRIM (discard) */
 136#define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6) /* Send WRITE_ZEROES */
 137#define NBD_FLAG_SEND_DF           (1 << 7) /* Send DF (Do not Fragment) */
 138#define NBD_FLAG_CAN_MULTI_CONN    (1 << 8) /* Multi-client cache consistent */
 139#define NBD_FLAG_SEND_RESIZE       (1 << 9) /* Send resize */
 140#define NBD_FLAG_SEND_CACHE        (1 << 10) /* Send CACHE (prefetch) */
 141
 142/* New-style handshake (global) flags, sent from server to client, and
 143   control what will happen during handshake phase. */
 144#define NBD_FLAG_FIXED_NEWSTYLE   (1 << 0) /* Fixed newstyle protocol. */
 145#define NBD_FLAG_NO_ZEROES        (1 << 1) /* End handshake without zeroes. */
 146
 147/* New-style client flags, sent from client to server to control what happens
 148   during handshake phase. */
 149#define NBD_FLAG_C_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */
 150#define NBD_FLAG_C_NO_ZEROES      (1 << 1) /* End handshake without zeroes. */
 151
 152/* Option requests. */
 153#define NBD_OPT_EXPORT_NAME       (1)
 154#define NBD_OPT_ABORT             (2)
 155#define NBD_OPT_LIST              (3)
 156/* #define NBD_OPT_PEEK_EXPORT    (4) not in use */
 157#define NBD_OPT_STARTTLS          (5)
 158#define NBD_OPT_INFO              (6)
 159#define NBD_OPT_GO                (7)
 160#define NBD_OPT_STRUCTURED_REPLY  (8)
 161#define NBD_OPT_LIST_META_CONTEXT (9)
 162#define NBD_OPT_SET_META_CONTEXT  (10)
 163
 164/* Option reply types. */
 165#define NBD_REP_ERR(value) ((UINT32_C(1) << 31) | (value))
 166
 167#define NBD_REP_ACK             (1)    /* Data sending finished. */
 168#define NBD_REP_SERVER          (2)    /* Export description. */
 169#define NBD_REP_INFO            (3)    /* NBD_OPT_INFO/GO. */
 170#define NBD_REP_META_CONTEXT    (4)    /* NBD_OPT_{LIST,SET}_META_CONTEXT */
 171
 172#define NBD_REP_ERR_UNSUP           NBD_REP_ERR(1)  /* Unknown option */
 173#define NBD_REP_ERR_POLICY          NBD_REP_ERR(2)  /* Server denied */
 174#define NBD_REP_ERR_INVALID         NBD_REP_ERR(3)  /* Invalid length */
 175#define NBD_REP_ERR_PLATFORM        NBD_REP_ERR(4)  /* Not compiled in */
 176#define NBD_REP_ERR_TLS_REQD        NBD_REP_ERR(5)  /* TLS required */
 177#define NBD_REP_ERR_UNKNOWN         NBD_REP_ERR(6)  /* Export unknown */
 178#define NBD_REP_ERR_SHUTDOWN        NBD_REP_ERR(7)  /* Server shutting down */
 179#define NBD_REP_ERR_BLOCK_SIZE_REQD NBD_REP_ERR(8)  /* Need INFO_BLOCK_SIZE */
 180
 181/* Info types, used during NBD_REP_INFO */
 182#define NBD_INFO_EXPORT         0
 183#define NBD_INFO_NAME           1
 184#define NBD_INFO_DESCRIPTION    2
 185#define NBD_INFO_BLOCK_SIZE     3
 186
 187/* Request flags, sent from client to server during transmission phase */
 188#define NBD_CMD_FLAG_FUA        (1 << 0) /* 'force unit access' during write */
 189#define NBD_CMD_FLAG_NO_HOLE    (1 << 1) /* don't punch hole on zero run */
 190#define NBD_CMD_FLAG_DF         (1 << 2) /* don't fragment structured read */
 191#define NBD_CMD_FLAG_REQ_ONE    (1 << 3) /* only one extent in BLOCK_STATUS
 192                                          * reply chunk */
 193
 194/* Supported request types */
 195enum {
 196    NBD_CMD_READ = 0,
 197    NBD_CMD_WRITE = 1,
 198    NBD_CMD_DISC = 2,
 199    NBD_CMD_FLUSH = 3,
 200    NBD_CMD_TRIM = 4,
 201    NBD_CMD_CACHE = 5,
 202    NBD_CMD_WRITE_ZEROES = 6,
 203    NBD_CMD_BLOCK_STATUS = 7,
 204};
 205
 206#define NBD_DEFAULT_PORT        10809
 207
 208/* Maximum size of a single READ/WRITE data buffer */
 209#define NBD_MAX_BUFFER_SIZE (32 * 1024 * 1024)
 210
 211/* Maximum size of an export name. The NBD spec requires 256 and
 212 * suggests that servers support up to 4096, but we stick to only the
 213 * required size so that we can stack-allocate the names, and because
 214 * going larger would require an audit of more code to make sure we
 215 * aren't overflowing some other buffer. */
 216#define NBD_MAX_NAME_SIZE 256
 217
 218/* Two types of reply structures */
 219#define NBD_SIMPLE_REPLY_MAGIC      0x67446698
 220#define NBD_STRUCTURED_REPLY_MAGIC  0x668e33ef
 221
 222/* Structured reply flags */
 223#define NBD_REPLY_FLAG_DONE          (1 << 0) /* This reply-chunk is last */
 224
 225/* Structured reply types */
 226#define NBD_REPLY_ERR(value)         ((1 << 15) | (value))
 227
 228#define NBD_REPLY_TYPE_NONE          0
 229#define NBD_REPLY_TYPE_OFFSET_DATA   1
 230#define NBD_REPLY_TYPE_OFFSET_HOLE   2
 231#define NBD_REPLY_TYPE_BLOCK_STATUS  5
 232#define NBD_REPLY_TYPE_ERROR         NBD_REPLY_ERR(1)
 233#define NBD_REPLY_TYPE_ERROR_OFFSET  NBD_REPLY_ERR(2)
 234
 235/* Extent flags for base:allocation in NBD_REPLY_TYPE_BLOCK_STATUS */
 236#define NBD_STATE_HOLE (1 << 0)
 237#define NBD_STATE_ZERO (1 << 1)
 238
 239/* Extent flags for qemu:dirty-bitmap in NBD_REPLY_TYPE_BLOCK_STATUS */
 240#define NBD_STATE_DIRTY (1 << 0)
 241
 242static inline bool nbd_reply_type_is_error(int type)
 243{
 244    return type & (1 << 15);
 245}
 246
 247/* NBD errors are based on errno numbers, so there is a 1:1 mapping,
 248 * but only a limited set of errno values is specified in the protocol.
 249 * Everything else is squashed to EINVAL.
 250 */
 251#define NBD_SUCCESS    0
 252#define NBD_EPERM      1
 253#define NBD_EIO        5
 254#define NBD_ENOMEM     12
 255#define NBD_EINVAL     22
 256#define NBD_ENOSPC     28
 257#define NBD_EOVERFLOW  75
 258#define NBD_ESHUTDOWN  108
 259
 260/* Details collected by NBD_OPT_EXPORT_NAME and NBD_OPT_GO */
 261struct NBDExportInfo {
 262    /* Set by client before nbd_receive_negotiate() */
 263    bool request_sizes;
 264    char *x_dirty_bitmap;
 265
 266    /* In-out fields, set by client before nbd_receive_negotiate() and
 267     * updated by server results during nbd_receive_negotiate() */
 268    bool structured_reply;
 269    bool base_allocation; /* base:allocation context for NBD_CMD_BLOCK_STATUS */
 270
 271    /* Set by server results during nbd_receive_negotiate() */
 272    uint64_t size;
 273    uint16_t flags;
 274    uint32_t min_block;
 275    uint32_t opt_block;
 276    uint32_t max_block;
 277
 278    uint32_t meta_base_allocation_id;
 279};
 280typedef struct NBDExportInfo NBDExportInfo;
 281
 282int nbd_receive_negotiate(QIOChannel *ioc, const char *name,
 283                          QCryptoTLSCreds *tlscreds, const char *hostname,
 284                          QIOChannel **outioc, NBDExportInfo *info,
 285                          Error **errp);
 286int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info,
 287             Error **errp);
 288int nbd_send_request(QIOChannel *ioc, NBDRequest *request);
 289int nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp);
 290int nbd_client(int fd);
 291int nbd_disconnect(int fd);
 292int nbd_errno_to_system_errno(int err);
 293
 294typedef struct NBDExport NBDExport;
 295typedef struct NBDClient NBDClient;
 296
 297NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset, off_t size,
 298                          uint16_t nbdflags, void (*close)(NBDExport *),
 299                          bool writethrough, BlockBackend *on_eject_blk,
 300                          Error **errp);
 301void nbd_export_close(NBDExport *exp);
 302void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp);
 303void nbd_export_get(NBDExport *exp);
 304void nbd_export_put(NBDExport *exp);
 305
 306BlockBackend *nbd_export_get_blockdev(NBDExport *exp);
 307
 308NBDExport *nbd_export_find(const char *name);
 309void nbd_export_set_name(NBDExport *exp, const char *name);
 310void nbd_export_set_description(NBDExport *exp, const char *description);
 311void nbd_export_close_all(void);
 312
 313void nbd_client_new(QIOChannelSocket *sioc,
 314                    QCryptoTLSCreds *tlscreds,
 315                    const char *tlsaclname,
 316                    void (*close_fn)(NBDClient *, bool));
 317void nbd_client_get(NBDClient *client);
 318void nbd_client_put(NBDClient *client);
 319
 320void nbd_server_start(SocketAddress *addr, const char *tls_creds,
 321                      Error **errp);
 322
 323void nbd_export_bitmap(NBDExport *exp, const char *bitmap,
 324                       const char *bitmap_export_name, Error **errp);
 325
 326/* nbd_read
 327 * Reads @size bytes from @ioc. Returns 0 on success.
 328 */
 329static inline int nbd_read(QIOChannel *ioc, void *buffer, size_t size,
 330                           Error **errp)
 331{
 332    return qio_channel_read_all(ioc, buffer, size, errp) < 0 ? -EIO : 0;
 333}
 334
 335static inline bool nbd_reply_is_simple(NBDReply *reply)
 336{
 337    return reply->magic == NBD_SIMPLE_REPLY_MAGIC;
 338}
 339
 340static inline bool nbd_reply_is_structured(NBDReply *reply)
 341{
 342    return reply->magic == NBD_STRUCTURED_REPLY_MAGIC;
 343}
 344
 345const char *nbd_reply_type_lookup(uint16_t type);
 346
 347#endif
 348