blockdev-nbd.c

   1 /*
   2  * Serving QEMU block devices via NBD
   3  *
   4  * Copyright (c) 2012 Red Hat, Inc.
   5  *
   6  * Author: Paolo Bonzini <pbonzini@redhat.com>
   7  *
   8  * This work is licensed under the terms of the GNU GPL, version 2 or
   9  * later.  See the COPYING file in the top-level directory.
  10  */
  11
  12 #include "qemu/osdep.h"
  13 #include "sysemu/blockdev.h"
  14 #include "sysemu/block-backend.h"
  15 #include "hw/block/block.h"
  16 #include "qapi/error.h"
  17 #include "qapi/qapi-commands-block-export.h"
  18 #include "block/nbd.h"
  19 #include "io/channel-socket.h"
  20 #include "io/net-listener.h"
  21
  22 typedef struct NBDServerData {
  23     QIONetListener *listener;
  24     QCryptoTLSCreds *tlscreds;
  25     char *tlsauthz;
  26     uint32_t max_connections;
  27     uint32_t connections;
  28 } NBDServerData;
  29
  30 static NBDServerData *nbd_server;
  31 static bool is_qemu_nbd;
  32
  33 static void nbd_update_server_watch(NBDServerData *s);
  34
  35 void nbd_server_is_qemu_nbd(bool value)
  36 {
  37     is_qemu_nbd = value;
  38 }
  39
  40 static void nbd_blockdev_client_closed(NBDClient *client, bool ignored)
  41 {
  42     nbd_client_put(client);
  43     assert(nbd_server->connections > 0);
  44     nbd_server->connections--;
  45     nbd_update_server_watch(nbd_server);
  46 }
  47
  48 static void nbd_accept(QIONetListener *listener, QIOChannelSocket *cioc,
  49                        gpointer opaque)
  50 {
  51     nbd_server->connections++;
  52     nbd_update_server_watch(nbd_server);
  53
  54     qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server");
  55     nbd_client_new(cioc, nbd_server->tlscreds, nbd_server->tlsauthz,
  56                    nbd_blockdev_client_closed);
  57 }
  58
  59 static void nbd_update_server_watch(NBDServerData *s)
  60 {
  61     if (!s->max_connections || s->connections < s->max_connections) {
  62         qio_net_listener_set_client_func(s->listener, nbd_accept, NULL, NULL);
  63     } else {
  64         qio_net_listener_set_client_func(s->listener, NULL, NULL, NULL);
  65     }
  66 }
  67
  68 static void nbd_server_free(NBDServerData *server)
  69 {
  70     if (!server) {
  71         return;
  72     }
  73
  74     qio_net_listener_disconnect(server->listener);
  75     object_unref(OBJECT(server->listener));
  76     if (server->tlscreds) {
  77         object_unref(OBJECT(server->tlscreds));
  78     }
  79     g_free(server->tlsauthz);
  80
  81     g_free(server);
  82 }
  83
  84 static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp)
  85 {
  86     Object *obj;
  87     QCryptoTLSCreds *creds;
  88
  89     obj = object_resolve_path_component(
  90         object_get_objects_root(), id);
  91     if (!obj) {
  92         error_setg(errp, "No TLS credentials with id '%s'",
  93                    id);
  94         return NULL;
  95     }
  96     creds = (QCryptoTLSCreds *)
  97         object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS);
  98     if (!creds) {
  99         error_setg(errp, "Object with id '%s' is not TLS credentials",
 100                    id);
 101         return NULL;
 102     }
 103
 104     if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
 105         error_setg(errp,
 106                    "Expecting TLS credentials with a server endpoint");
 107         return NULL;
 108     }
 109     object_ref(obj);
 110     return creds;
 111 }
 112
 113
 114 void nbd_server_start(SocketAddress *addr, const char *tls_creds,
 115                       const char *tls_authz, uint32_t max_connections,
 116                       Error **errp)
 117 {
 118     if (nbd_server) {
 119         error_setg(errp, "NBD server already running");
 120         return;
 121     }
 122
 123     nbd_server = g_new0(NBDServerData, 1);
 124     nbd_server->max_connections = max_connections;
 125     nbd_server->listener = qio_net_listener_new();
 126
 127     qio_net_listener_set_name(nbd_server->listener,
 128                               "nbd-listener");
 129
 130     if (qio_net_listener_open_sync(nbd_server->listener, addr, 1, errp) < 0) {
 131         goto error;
 132     }
 133
 134     if (tls_creds) {
 135         nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp);
 136         if (!nbd_server->tlscreds) {
 137             goto error;
 138         }
 139
 140         /* TODO SOCKET_ADDRESS_TYPE_FD where fd has AF_INET or AF_INET6 */
 141         if (addr->type != SOCKET_ADDRESS_TYPE_INET) {
 142             error_setg(errp, "TLS is only supported with IPv4/IPv6");
 143             goto error;
 144         }
 145     }
 146
 147     nbd_server->tlsauthz = g_strdup(tls_authz);
 148
 149     nbd_update_server_watch(nbd_server);
 150
 151     return;
 152
 153  error:
 154     nbd_server_free(nbd_server);
 155     nbd_server = NULL;
 156 }
 157
 158 void nbd_server_start_options(NbdServerOptions *arg, Error **errp)
 159 {
 160     nbd_server_start(arg->addr, arg->tls_creds, arg->tls_authz,
 161                      arg->max_connections, errp);
 162 }
 163
 164 void qmp_nbd_server_start(SocketAddressLegacy *addr,
 165                           bool has_tls_creds, const char *tls_creds,
 166                           bool has_tls_authz, const char *tls_authz,
 167                           bool has_max_connections, uint32_t max_connections,
 168                           Error **errp)
 169 {
 170     SocketAddress *addr_flat = socket_address_flatten(addr);
 171
 172     nbd_server_start(addr_flat, tls_creds, tls_authz, max_connections, errp);
 173     qapi_free_SocketAddress(addr_flat);
 174 }
 175
 176 int nbd_export_create(BlockExport *exp, BlockExportOptions *exp_args,
 177                       Error **errp)
 178 {
 179     BlockExportOptionsNbd *arg = &exp_args->u.nbd;
 180     BlockDriverState *bs = NULL;
 181     AioContext *aio_context;
 182     int ret;
 183
 184     assert(exp_args->type == BLOCK_EXPORT_TYPE_NBD);
 185
 186     if (!nbd_server && !is_qemu_nbd) {
 187         error_setg(errp, "NBD server not running");
 188         return -EINVAL;
 189     }
 190
 191     if (!arg->has_name) {
 192         arg->name = exp_args->node_name;
 193     }
 194
 195     if (strlen(arg->name) > NBD_MAX_STRING_SIZE) {
 196         error_setg(errp, "export name '%s' too long", arg->name);
 197         return -EINVAL;
 198     }
 199
 200     if (arg->description && strlen(arg->description) > NBD_MAX_STRING_SIZE) {
 201         error_setg(errp, "description '%s' too long", arg->description);
 202         return -EINVAL;
 203     }
 204
 205     if (nbd_export_find(arg->name)) {
 206         error_setg(errp, "NBD server already has export named '%s'", arg->name);
 207         return -EEXIST;
 208     }
 209
 210     bs = bdrv_lookup_bs(NULL, exp_args->node_name, errp);
 211     if (!bs) {
 212         return -ENOENT;
 213     }
 214
 215     aio_context = bdrv_get_aio_context(bs);
 216     aio_context_acquire(aio_context);
 217
 218     if (!arg->has_writable) {
 219         arg->writable = false;
 220     }
 221     if (bdrv_is_read_only(bs) && arg->writable) {
 222         ret = -EINVAL;
 223         error_setg(errp, "Cannot export read-only node as writable");
 224         goto out;
 225     }
 226
 227     if (!exp_args->has_writethrough) {
 228         exp_args->writethrough = false;
 229     }
 230
 231     ret = nbd_export_new(exp, bs, arg->name, arg->description, arg->bitmap,
 232                          !arg->writable, !arg->writable,
 233                          exp_args->writethrough, errp);
 234     if (ret < 0) {
 235         goto out;
 236     }
 237
 238     /* The list of named exports has a strong reference to this export now and
 239      * our only way of accessing it is through nbd_export_find(), so we can drop
 240      * the strong reference that is @exp. */
 241     blk_exp_unref(exp);
 242
 243     ret = 0;
 244  out:
 245     aio_context_release(aio_context);
 246     return ret;
 247 }
 248
 249 void qmp_nbd_server_add(NbdServerAddOptions *arg, Error **errp)
 250 {
 251     BlockExport *export;
 252     BlockDriverState *bs;
 253     BlockBackend *on_eject_blk;
 254     BlockExportOptions *export_opts;
 255
 256     bs = bdrv_lookup_bs(arg->device, arg->device, errp);
 257     if (!bs) {
 258         return;
 259     }
 260
 261     /*
 262      * block-export-add would default to the node-name, but we may have to use
 263      * the device name as a default here for compatibility.
 264      */
 265     if (!arg->has_name) {
 266         arg->name = arg->device;
 267     }
 268
 269     export_opts = g_new(BlockExportOptions, 1);
 270     *export_opts = (BlockExportOptions) {
 271         .type                   = BLOCK_EXPORT_TYPE_NBD,
 272         .node_name              = g_strdup(bdrv_get_node_name(bs)),
 273         .u.nbd = {
 274             .has_name           = true,
 275             .name               = g_strdup(arg->name),
 276             .has_description    = arg->has_description,
 277             .description        = g_strdup(arg->description),
 278             .has_writable       = arg->has_writable,
 279             .writable           = arg->writable,
 280             .has_bitmap         = arg->has_bitmap,
 281             .bitmap             = g_strdup(arg->bitmap),
 282         },
 283     };
 284
 285     /*
 286      * nbd-server-add doesn't complain when a read-only device should be
 287      * exported as writable, but simply downgrades it. This is an error with
 288      * block-export-add.
 289      */
 290     if (bdrv_is_read_only(bs)) {
 291         export_opts->u.nbd.has_writable = true;
 292         export_opts->u.nbd.writable = false;
 293     }
 294
 295     export = blk_exp_add(export_opts, errp);
 296     if (!export) {
 297         goto fail;
 298     }
 299
 300     /*
 301      * nbd-server-add removes the export when the named BlockBackend used for
 302      * @device goes away.
 303      */
 304     on_eject_blk = blk_by_name(arg->device);
 305     if (on_eject_blk) {
 306         nbd_export_set_on_eject_blk(export, on_eject_blk);
 307     }
 308
 309 fail:
 310     qapi_free_BlockExportOptions(export_opts);
 311 }
 312
 313 void qmp_nbd_server_remove(const char *name,
 314                            bool has_mode, NbdServerRemoveMode mode,
 315                            Error **errp)
 316 {
 317     NBDExport *exp;
 318     AioContext *aio_context;
 319
 320     if (!nbd_server) {
 321         error_setg(errp, "NBD server not running");
 322         return;
 323     }
 324
 325     exp = nbd_export_find(name);
 326     if (exp == NULL) {
 327         error_setg(errp, "Export '%s' is not found", name);
 328         return;
 329     }
 330
 331     if (!has_mode) {
 332         mode = NBD_SERVER_REMOVE_MODE_SAFE;
 333     }
 334
 335     aio_context = nbd_export_aio_context(exp);
 336     aio_context_acquire(aio_context);
 337     nbd_export_remove(exp, mode, errp);
 338     aio_context_release(aio_context);
 339 }
 340
 341 void qmp_nbd_server_stop(Error **errp)
 342 {
 343     if (!nbd_server) {
 344         error_setg(errp, "NBD server not running");
 345         return;
 346     }
 347
 348     nbd_export_close_all();
 349
 350     nbd_server_free(nbd_server);
 351     nbd_server = NULL;
 352 }