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
 139/* New-style handshake (global) flags, sent from server to client, and
 140   control what will happen during handshake phase. */
 141#define NBD_FLAG_FIXED_NEWSTYLE   (1 << 0) /* Fixed newstyle protocol. */
 142#define NBD_FLAG_NO_ZEROES        (1 << 1) /* End handshake without zeroes. */
 143
 144/* New-style client flags, sent from client to server to control what happens
 145   during handshake phase. */
 146#define NBD_FLAG_C_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */
 147#define NBD_FLAG_C_NO_ZEROES      (1 << 1) /* End handshake without zeroes. */
 148
 149/* Option requests. */
 150#define NBD_OPT_EXPORT_NAME       (1)
 151#define NBD_OPT_ABORT             (2)
 152#define NBD_OPT_LIST              (3)
 153/* #define NBD_OPT_PEEK_EXPORT    (4) not in use */
 154#define NBD_OPT_STARTTLS          (5)
 155#define NBD_OPT_INFO              (6)
 156#define NBD_OPT_GO                (7)
 157#define NBD_OPT_STRUCTURED_REPLY  (8)
 158#define NBD_OPT_LIST_META_CONTEXT (9)
 159#define NBD_OPT_SET_META_CONTEXT  (10)
 160
 161/* Option reply types. */
 162#define NBD_REP_ERR(value) ((UINT32_C(1) << 31) | (value))
 163
 164#define NBD_REP_ACK             (1)    /* Data sending finished. */
 165#define NBD_REP_SERVER          (2)    /* Export description. */
 166#define NBD_REP_INFO            (3)    /* NBD_OPT_INFO/GO. */
 167#define NBD_REP_META_CONTEXT    (4)    /* NBD_OPT_{LIST,SET}_META_CONTEXT */
 168
 169#define NBD_REP_ERR_UNSUP           NBD_REP_ERR(1)  /* Unknown option */
 170#define NBD_REP_ERR_POLICY          NBD_REP_ERR(2)  /* Server denied */
 171#define NBD_REP_ERR_INVALID         NBD_REP_ERR(3)  /* Invalid length */
 172#define NBD_REP_ERR_PLATFORM        NBD_REP_ERR(4)  /* Not compiled in */
 173#define NBD_REP_ERR_TLS_REQD        NBD_REP_ERR(5)  /* TLS required */
 174#define NBD_REP_ERR_UNKNOWN         NBD_REP_ERR(6)  /* Export unknown */
 175#define NBD_REP_ERR_SHUTDOWN        NBD_REP_ERR(7)  /* Server shutting down */
 176#define NBD_REP_ERR_BLOCK_SIZE_REQD NBD_REP_ERR(8)  /* Need INFO_BLOCK_SIZE */
 177
 178/* Info types, used during NBD_REP_INFO */
 179#define NBD_INFO_EXPORT         0
 180#define NBD_INFO_NAME           1
 181#define NBD_INFO_DESCRIPTION    2
 182#define NBD_INFO_BLOCK_SIZE     3
 183
 184/* Request flags, sent from client to server during transmission phase */
 185#define NBD_CMD_FLAG_FUA        (1 << 0) /* 'force unit access' during write */
 186#define NBD_CMD_FLAG_NO_HOLE    (1 << 1) /* don't punch hole on zero run */
 187#define NBD_CMD_FLAG_DF         (1 << 2) /* don't fragment structured read */
 188#define NBD_CMD_FLAG_REQ_ONE    (1 << 3) /* only one extent in BLOCK_STATUS
 189                                          * reply chunk */
 190
 191/* Supported request types */
 192enum {
 193    NBD_CMD_READ = 0,
 194    NBD_CMD_WRITE = 1,
 195    NBD_CMD_DISC = 2,
 196    NBD_CMD_FLUSH = 3,
 197    NBD_CMD_TRIM = 4,
 198    /* 5 reserved for failed experiment NBD_CMD_CACHE */
 199    NBD_CMD_WRITE_ZEROES = 6,
 200    NBD_CMD_BLOCK_STATUS = 7,
 201};
 202
 203#define NBD_DEFAULT_PORT        10809
 204
 205/* Maximum size of a single READ/WRITE data buffer */
 206#define NBD_MAX_BUFFER_SIZE (32 * 1024 * 1024)
 207
 208/* Maximum size of an export name. The NBD spec requires 256 and
 209 * suggests that servers support up to 4096, but we stick to only the
 210 * required size so that we can stack-allocate the names, and because
 211 * going larger would require an audit of more code to make sure we
 212 * aren't overflowing some other buffer. */
 213#define NBD_MAX_NAME_SIZE 256
 214
 215/* Two types of reply structures */
 216#define NBD_SIMPLE_REPLY_MAGIC      0x67446698
 217#define NBD_STRUCTURED_REPLY_MAGIC  0x668e33ef
 218
 219/* Structured reply flags */
 220#define NBD_REPLY_FLAG_DONE          (1 << 0) /* This reply-chunk is last */
 221
 222/* Structured reply types */
 223#define NBD_REPLY_ERR(value)         ((1 << 15) | (value))
 224
 225#define NBD_REPLY_TYPE_NONE          0
 226#define NBD_REPLY_TYPE_OFFSET_DATA   1
 227#define NBD_REPLY_TYPE_OFFSET_HOLE   2
 228#define NBD_REPLY_TYPE_BLOCK_STATUS  5
 229#define NBD_REPLY_TYPE_ERROR         NBD_REPLY_ERR(1)
 230#define NBD_REPLY_TYPE_ERROR_OFFSET  NBD_REPLY_ERR(2)
 231
 232/* Flags for extents (NBDExtent.flags) of NBD_REPLY_TYPE_BLOCK_STATUS,
 233 * for base:allocation meta context */
 234#define NBD_STATE_HOLE (1 << 0)
 235#define NBD_STATE_ZERO (1 << 1)
 236
 237static inline bool nbd_reply_type_is_error(int type)
 238{
 239    return type & (1 << 15);
 240}
 241
 242/* NBD errors are based on errno numbers, so there is a 1:1 mapping,
 243 * but only a limited set of errno values is specified in the protocol.
 244 * Everything else is squashed to EINVAL.
 245 */
 246#define NBD_SUCCESS    0
 247#define NBD_EPERM      1
 248#define NBD_EIO        5
 249#define NBD_ENOMEM     12
 250#define NBD_EINVAL     22
 251#define NBD_ENOSPC     28
 252#define NBD_EOVERFLOW  75
 253#define NBD_ESHUTDOWN  108
 254
 255/* Details collected by NBD_OPT_EXPORT_NAME and NBD_OPT_GO */
 256struct NBDExportInfo {
 257    /* Set by client before nbd_receive_negotiate() */
 258    bool request_sizes;
 259
 260    /* In-out fields, set by client before nbd_receive_negotiate() and
 261     * updated by server results during nbd_receive_negotiate() */
 262    bool structured_reply;
 263    bool base_allocation; /* base:allocation context for NBD_CMD_BLOCK_STATUS */
 264
 265    /* Set by server results during nbd_receive_negotiate() */
 266    uint64_t size;
 267    uint16_t flags;
 268    uint32_t min_block;
 269    uint32_t opt_block;
 270    uint32_t max_block;
 271
 272    uint32_t meta_base_allocation_id;
 273};
 274typedef struct NBDExportInfo NBDExportInfo;
 275
 276int nbd_receive_negotiate(QIOChannel *ioc, const char *name,
 277                          QCryptoTLSCreds *tlscreds, const char *hostname,
 278                          QIOChannel **outioc, NBDExportInfo *info,
 279                          Error **errp);
 280int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info,
 281             Error **errp);
 282int nbd_send_request(QIOChannel *ioc, NBDRequest *request);
 283int nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp);
 284int nbd_client(int fd);
 285int nbd_disconnect(int fd);
 286int nbd_errno_to_system_errno(int err);
 287
 288typedef struct NBDExport NBDExport;
 289typedef struct NBDClient NBDClient;
 290
 291NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset, off_t size,
 292                          uint16_t nbdflags, void (*close)(NBDExport *),
 293                          bool writethrough, BlockBackend *on_eject_blk,
 294                          Error **errp);
 295void nbd_export_close(NBDExport *exp);
 296void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp);
 297void nbd_export_get(NBDExport *exp);
 298void nbd_export_put(NBDExport *exp);
 299
 300BlockBackend *nbd_export_get_blockdev(NBDExport *exp);
 301
 302NBDExport *nbd_export_find(const char *name);
 303void nbd_export_set_name(NBDExport *exp, const char *name);
 304void nbd_export_set_description(NBDExport *exp, const char *description);
 305void nbd_export_close_all(void);
 306
 307void nbd_client_new(NBDExport *exp,
 308                    QIOChannelSocket *sioc,
 309                    QCryptoTLSCreds *tlscreds,
 310                    const char *tlsaclname,
 311                    void (*close_fn)(NBDClient *, bool));
 312void nbd_client_get(NBDClient *client);
 313void nbd_client_put(NBDClient *client);
 314
 315void nbd_server_start(SocketAddress *addr, const char *tls_creds,
 316                      Error **errp);
 317
 318
 319/* nbd_read
 320 * Reads @size bytes from @ioc. Returns 0 on success.
 321 */
 322static inline int nbd_read(QIOChannel *ioc, void *buffer, size_t size,
 323                           Error **errp)
 324{
 325    return qio_channel_read_all(ioc, buffer, size, errp) < 0 ? -EIO : 0;
 326}
 327
 328static inline bool nbd_reply_is_simple(NBDReply *reply)
 329{
 330    return reply->magic == NBD_SIMPLE_REPLY_MAGIC;
 331}
 332
 333static inline bool nbd_reply_is_structured(NBDReply *reply)
 334{
 335    return reply->magic == NBD_STRUCTURED_REPLY_MAGIC;
 336}
 337
 338const char *nbd_reply_type_lookup(uint16_t type);
 339
 340#endif
 341