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 } NBDServerData;
  27
  28 static NBDServerData *nbd_server;
  29
  30 static void nbd_blockdev_client_closed(NBDClient *client, bool ignored)
  31 {
  32     nbd_client_put(client);
  33 }
  34
  35 static void nbd_accept(QIONetListener *listener, QIOChannelSocket *cioc,
  36                        gpointer opaque)
  37 {
  38     qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server");
  39     nbd_client_new(cioc, nbd_server->tlscreds, nbd_server->tlsauthz,
  40                    nbd_blockdev_client_closed);
  41 }
  42
  43
  44 static void nbd_server_free(NBDServerData *server)
  45 {
  46     if (!server) {
  47         return;
  48     }
  49
  50     qio_net_listener_disconnect(server->listener);
  51     object_unref(OBJECT(server->listener));
  52     if (server->tlscreds) {
  53         object_unref(OBJECT(server->tlscreds));
  54     }
  55     g_free(server->tlsauthz);
  56
  57     g_free(server);
  58 }
  59
  60 static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp)
  61 {
  62     Object *obj;
  63     QCryptoTLSCreds *creds;
  64
  65     obj = object_resolve_path_component(
  66         object_get_objects_root(), id);
  67     if (!obj) {
  68         error_setg(errp, "No TLS credentials with id '%s'",
  69                    id);
  70         return NULL;
  71     }
  72     creds = (QCryptoTLSCreds *)
  73         object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS);
  74     if (!creds) {
  75         error_setg(errp, "Object with id '%s' is not TLS credentials",
  76                    id);
  77         return NULL;
  78     }
  79
  80     if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
  81         error_setg(errp,
  82                    "Expecting TLS credentials with a server endpoint");
  83         return NULL;
  84     }
  85     object_ref(obj);
  86     return creds;
  87 }
  88
  89
  90 void nbd_server_start(SocketAddress *addr, const char *tls_creds,
  91                       const char *tls_authz, Error **errp)
  92 {
  93     if (nbd_server) {
  94         error_setg(errp, "NBD server already running");
  95         return;
  96     }
  97
  98     nbd_server = g_new0(NBDServerData, 1);
  99     nbd_server->listener = qio_net_listener_new();
 100
 101     qio_net_listener_set_name(nbd_server->listener,
 102                               "nbd-listener");
 103
 104     if (qio_net_listener_open_sync(nbd_server->listener, addr, 1, errp) < 0) {
 105         goto error;
 106     }
 107
 108     if (tls_creds) {
 109         nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp);
 110         if (!nbd_server->tlscreds) {
 111             goto error;
 112         }
 113
 114         /* TODO SOCKET_ADDRESS_TYPE_FD where fd has AF_INET or AF_INET6 */
 115         if (addr->type != SOCKET_ADDRESS_TYPE_INET) {
 116             error_setg(errp, "TLS is only supported with IPv4/IPv6");
 117             goto error;
 118         }
 119     }
 120
 121     nbd_server->tlsauthz = g_strdup(tls_authz);
 122
 123     qio_net_listener_set_client_func(nbd_server->listener,
 124                                      nbd_accept,
 125                                      NULL,
 126                                      NULL);
 127
 128     return;
 129
 130  error:
 131     nbd_server_free(nbd_server);
 132     nbd_server = NULL;
 133 }
 134
 135 void nbd_server_start_options(NbdServerOptions *arg, Error **errp)
 136 {
 137     nbd_server_start(arg->addr, arg->tls_creds, arg->tls_authz, errp);
 138 }
 139
 140 void qmp_nbd_server_start(SocketAddressLegacy *addr,
 141                           bool has_tls_creds, const char *tls_creds,
 142                           bool has_tls_authz, const char *tls_authz,
 143                           Error **errp)
 144 {
 145     SocketAddress *addr_flat = socket_address_flatten(addr);
 146
 147     nbd_server_start(addr_flat, tls_creds, tls_authz, errp);
 148     qapi_free_SocketAddress(addr_flat);
 149 }
 150
 151 BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
 152 {
 153     BlockExportOptionsNbd *arg = &exp_args->u.nbd;
 154     BlockDriverState *bs = NULL;
 155     NBDExport *exp = NULL;
 156     AioContext *aio_context;
 157
 158     assert(exp_args->type == BLOCK_EXPORT_TYPE_NBD);
 159
 160     if (!nbd_server) {
 161         error_setg(errp, "NBD server not running");
 162         return NULL;
 163     }
 164
 165     if (!arg->has_name) {
 166         arg->name = arg->device;
 167     }
 168
 169     if (strlen(arg->name) > NBD_MAX_STRING_SIZE) {
 170         error_setg(errp, "export name '%s' too long", arg->name);
 171         return NULL;
 172     }
 173
 174     if (arg->description && strlen(arg->description) > NBD_MAX_STRING_SIZE) {
 175         error_setg(errp, "description '%s' too long", arg->description);
 176         return NULL;
 177     }
 178
 179     if (nbd_export_find(arg->name)) {
 180         error_setg(errp, "NBD server already has export named '%s'", arg->name);
 181         return NULL;
 182     }
 183
 184     bs = bdrv_lookup_bs(arg->device, arg->device, errp);
 185     if (!bs) {
 186         return NULL;
 187     }
 188
 189     aio_context = bdrv_get_aio_context(bs);
 190     aio_context_acquire(aio_context);
 191
 192     if (!arg->has_writable) {
 193         arg->writable = false;
 194     }
 195     if (bdrv_is_read_only(bs) && arg->writable) {
 196         error_setg(errp, "Cannot export read-only node as writable");
 197         goto out;
 198     }
 199
 200     exp = nbd_export_new(bs, arg->name, arg->description, arg->bitmap,
 201                          !arg->writable, !arg->writable,
 202                          NULL, false, errp);
 203     if (!exp) {
 204         goto out;
 205     }
 206
 207     /* The list of named exports has a strong reference to this export now and
 208      * our only way of accessing it is through nbd_export_find(), so we can drop
 209      * the strong reference that is @exp. */
 210     nbd_export_put(exp);
 211
 212  out:
 213     aio_context_release(aio_context);
 214     /* TODO Remove the cast: nbd_export_new() will return a BlockExport. */
 215     return (BlockExport*) exp;
 216 }
 217
 218 void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
 219 {
 220     BlockExport *export;
 221     BlockDriverState *bs;
 222     BlockBackend *on_eject_blk;
 223     BlockExportOptions export_opts;
 224
 225     bs = bdrv_lookup_bs(arg->device, arg->device, errp);
 226     if (!bs) {
 227         return;
 228     }
 229
 230     export_opts = (BlockExportOptions) {
 231         .type = BLOCK_EXPORT_TYPE_NBD,
 232         .u.nbd = *arg,
 233     };
 234
 235     /*
 236      * nbd-server-add doesn't complain when a read-only device should be
 237      * exported as writable, but simply downgrades it. This is an error with
 238      * block-export-add.
 239      */
 240     if (bdrv_is_read_only(bs)) {
 241         export_opts.u.nbd.has_writable = true;
 242         export_opts.u.nbd.writable = false;
 243     }
 244
 245     export = blk_exp_add(&export_opts, errp);
 246     if (!export) {
 247         return;
 248     }
 249
 250     /*
 251      * nbd-server-add removes the export when the named BlockBackend used for
 252      * @device goes away.
 253      */
 254     on_eject_blk = blk_by_name(arg->device);
 255     if (on_eject_blk) {
 256         nbd_export_set_on_eject_blk(export, on_eject_blk);
 257     }
 258 }
 259
 260 void qmp_nbd_server_remove(const char *name,
 261                            bool has_mode, NbdServerRemoveMode mode,
 262                            Error **errp)
 263 {
 264     NBDExport *exp;
 265     AioContext *aio_context;
 266
 267     if (!nbd_server) {
 268         error_setg(errp, "NBD server not running");
 269         return;
 270     }
 271
 272     exp = nbd_export_find(name);
 273     if (exp == NULL) {
 274         error_setg(errp, "Export '%s' is not found", name);
 275         return;
 276     }
 277
 278     if (!has_mode) {
 279         mode = NBD_SERVER_REMOVE_MODE_SAFE;
 280     }
 281
 282     aio_context = nbd_export_aio_context(exp);
 283     aio_context_acquire(aio_context);
 284     nbd_export_remove(exp, mode, errp);
 285     aio_context_release(aio_context);
 286 }
 287
 288 void qmp_nbd_server_stop(Error **errp)
 289 {
 290     if (!nbd_server) {
 291         error_setg(errp, "NBD server not running");
 292         return;
 293     }
 294
 295     nbd_export_close_all();
 296
 297     nbd_server_free(nbd_server);
 298     nbd_server = NULL;
 299 }