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
  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 struct NBDReply {
  61     uint64_t handle;
  62     uint32_t error;
  63 };
  64 typedef struct NBDReply NBDReply;
  65
  66 typedef struct NBDSimpleReply {
  67     uint32_t magic;  /* NBD_SIMPLE_REPLY_MAGIC */
  68     uint32_t error;
  69     uint64_t handle;
  70 } QEMU_PACKED NBDSimpleReply;
  71
  72 /* Transmission (export) flags: sent from server to client during handshake,
  73    but describe what will happen during transmission */
  74 #define NBD_FLAG_HAS_FLAGS         (1 << 0) /* Flags are there */
  75 #define NBD_FLAG_READ_ONLY         (1 << 1) /* Device is read-only */
  76 #define NBD_FLAG_SEND_FLUSH        (1 << 2) /* Send FLUSH */
  77 #define NBD_FLAG_SEND_FUA          (1 << 3) /* Send FUA (Force Unit Access) */
  78 #define NBD_FLAG_ROTATIONAL        (1 << 4) /* Use elevator algorithm -
  79                                                rotational media */
  80 #define NBD_FLAG_SEND_TRIM         (1 << 5) /* Send TRIM (discard) */
  81 #define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6) /* Send WRITE_ZEROES */
  82
  83 /* New-style handshake (global) flags, sent from server to client, and
  84    control what will happen during handshake phase. */
  85 #define NBD_FLAG_FIXED_NEWSTYLE   (1 << 0) /* Fixed newstyle protocol. */
  86 #define NBD_FLAG_NO_ZEROES        (1 << 1) /* End handshake without zeroes. */
  87
  88 /* New-style client flags, sent from client to server to control what happens
  89    during handshake phase. */
  90 #define NBD_FLAG_C_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */
  91 #define NBD_FLAG_C_NO_ZEROES      (1 << 1) /* End handshake without zeroes. */
  92
  93 /* Option requests. */
  94 #define NBD_OPT_EXPORT_NAME      (1)
  95 #define NBD_OPT_ABORT            (2)
  96 #define NBD_OPT_LIST             (3)
  97 /* #define NBD_OPT_PEEK_EXPORT   (4) not in use */
  98 #define NBD_OPT_STARTTLS         (5)
  99 #define NBD_OPT_INFO             (6)
 100 #define NBD_OPT_GO               (7)
 101 #define NBD_OPT_STRUCTURED_REPLY (8)
 102
 103 /* Option reply types. */
 104 #define NBD_REP_ERR(value) ((UINT32_C(1) << 31) | (value))
 105
 106 #define NBD_REP_ACK             (1)             /* Data sending finished. */
 107 #define NBD_REP_SERVER          (2)             /* Export description. */
 108 #define NBD_REP_INFO            (3)             /* NBD_OPT_INFO/GO. */
 109
 110 #define NBD_REP_ERR_UNSUP           NBD_REP_ERR(1)  /* Unknown option */
 111 #define NBD_REP_ERR_POLICY          NBD_REP_ERR(2)  /* Server denied */
 112 #define NBD_REP_ERR_INVALID         NBD_REP_ERR(3)  /* Invalid length */
 113 #define NBD_REP_ERR_PLATFORM        NBD_REP_ERR(4)  /* Not compiled in */
 114 #define NBD_REP_ERR_TLS_REQD        NBD_REP_ERR(5)  /* TLS required */
 115 #define NBD_REP_ERR_UNKNOWN         NBD_REP_ERR(6)  /* Export unknown */
 116 #define NBD_REP_ERR_SHUTDOWN        NBD_REP_ERR(7)  /* Server shutting down */
 117 #define NBD_REP_ERR_BLOCK_SIZE_REQD NBD_REP_ERR(8)  /* Need INFO_BLOCK_SIZE */
 118
 119 /* Info types, used during NBD_REP_INFO */
 120 #define NBD_INFO_EXPORT         0
 121 #define NBD_INFO_NAME           1
 122 #define NBD_INFO_DESCRIPTION    2
 123 #define NBD_INFO_BLOCK_SIZE     3
 124
 125 /* Request flags, sent from client to server during transmission phase */
 126 #define NBD_CMD_FLAG_FUA        (1 << 0) /* 'force unit access' during write */
 127 #define NBD_CMD_FLAG_NO_HOLE    (1 << 1) /* don't punch hole on zero run */
 128
 129 /* Supported request types */
 130 enum {
 131     NBD_CMD_READ = 0,
 132     NBD_CMD_WRITE = 1,
 133     NBD_CMD_DISC = 2,
 134     NBD_CMD_FLUSH = 3,
 135     NBD_CMD_TRIM = 4,
 136     /* 5 reserved for failed experiment NBD_CMD_CACHE */
 137     NBD_CMD_WRITE_ZEROES = 6,
 138 };
 139
 140 #define NBD_DEFAULT_PORT        10809
 141
 142 /* Maximum size of a single READ/WRITE data buffer */
 143 #define NBD_MAX_BUFFER_SIZE (32 * 1024 * 1024)
 144
 145 /* Maximum size of an export name. The NBD spec requires 256 and
 146  * suggests that servers support up to 4096, but we stick to only the
 147  * required size so that we can stack-allocate the names, and because
 148  * going larger would require an audit of more code to make sure we
 149  * aren't overflowing some other buffer. */
 150 #define NBD_MAX_NAME_SIZE 256
 151
 152 /* NBD errors are based on errno numbers, so there is a 1:1 mapping,
 153  * but only a limited set of errno values is specified in the protocol.
 154  * Everything else is squashed to EINVAL.
 155  */
 156 #define NBD_SUCCESS    0
 157 #define NBD_EPERM      1
 158 #define NBD_EIO        5
 159 #define NBD_ENOMEM     12
 160 #define NBD_EINVAL     22
 161 #define NBD_ENOSPC     28
 162 #define NBD_ESHUTDOWN  108
 163
 164 /* Details collected by NBD_OPT_EXPORT_NAME and NBD_OPT_GO */
 165 struct NBDExportInfo {
 166     /* Set by client before nbd_receive_negotiate() */
 167     bool request_sizes;
 168     /* Set by server results during nbd_receive_negotiate() */
 169     uint64_t size;
 170     uint16_t flags;
 171     uint32_t min_block;
 172     uint32_t opt_block;
 173     uint32_t max_block;
 174 };
 175 typedef struct NBDExportInfo NBDExportInfo;
 176
 177 int nbd_receive_negotiate(QIOChannel *ioc, const char *name,
 178                           QCryptoTLSCreds *tlscreds, const char *hostname,
 179                           QIOChannel **outioc, NBDExportInfo *info,
 180                           Error **errp);
 181 int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info,
 182              Error **errp);
 183 int nbd_send_request(QIOChannel *ioc, NBDRequest *request);
 184 int nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp);
 185 int nbd_client(int fd);
 186 int nbd_disconnect(int fd);
 187 int nbd_errno_to_system_errno(int err);
 188
 189 typedef struct NBDExport NBDExport;
 190 typedef struct NBDClient NBDClient;
 191
 192 NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset, off_t size,
 193                           uint16_t nbdflags, void (*close)(NBDExport *),
 194                           bool writethrough, BlockBackend *on_eject_blk,
 195                           Error **errp);
 196 void nbd_export_close(NBDExport *exp);
 197 void nbd_export_get(NBDExport *exp);
 198 void nbd_export_put(NBDExport *exp);
 199
 200 BlockBackend *nbd_export_get_blockdev(NBDExport *exp);
 201
 202 NBDExport *nbd_export_find(const char *name);
 203 void nbd_export_set_name(NBDExport *exp, const char *name);
 204 void nbd_export_set_description(NBDExport *exp, const char *description);
 205 void nbd_export_close_all(void);
 206
 207 void nbd_client_new(NBDExport *exp,
 208                     QIOChannelSocket *sioc,
 209                     QCryptoTLSCreds *tlscreds,
 210                     const char *tlsaclname,
 211                     void (*close_fn)(NBDClient *, bool));
 212 void nbd_client_get(NBDClient *client);
 213 void nbd_client_put(NBDClient *client);
 214
 215 void nbd_server_start(SocketAddress *addr, const char *tls_creds,
 216                       Error **errp);
 217
 218 #endif