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/clone-visitor.h"
  18 #include "qapi/qapi-visit-block-export.h"
  19 #include "qapi/qapi-commands-block-export.h"
  20 #include "block/nbd.h"
  21 #include "io/channel-socket.h"
  22 #include "io/net-listener.h"
  23
  24 typedef struct NBDServerData {
  25     QIONetListener *listener;
  26     QCryptoTLSCreds *tlscreds;
  27     char *tlsauthz;
  28     uint32_t max_connections;
  29     uint32_t connections;
  30 } NBDServerData;
  31
  32 static NBDServerData *nbd_server;
  33 static bool is_qemu_nbd;
  34
  35 static void nbd_update_server_watch(NBDServerData *s);
  36
  37 void nbd_server_is_qemu_nbd(bool value)
  38 {
  39     is_qemu_nbd = value;
  40 }
  41
  42 bool nbd_server_is_running(void)
  43 {
  44     return nbd_server || is_qemu_nbd;
  45 }
  46
  47 static void nbd_blockdev_client_closed(NBDClient *client, bool ignored)
  48 {
  49     nbd_client_put(client);
  50     assert(nbd_server->connections > 0);
  51     nbd_server->connections--;
  52     nbd_update_server_watch(nbd_server);
  53 }
  54
  55 static void nbd_accept(QIONetListener *listener, QIOChannelSocket *cioc,
  56                        gpointer opaque)
  57 {
  58     nbd_server->connections++;
  59     nbd_update_server_watch(nbd_server);
  60
  61     qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server");
  62     nbd_client_new(cioc, nbd_server->tlscreds, nbd_server->tlsauthz,
  63                    nbd_blockdev_client_closed);
  64 }
  65
  66 static void nbd_update_server_watch(NBDServerData *s)
  67 {
  68     if (!s->max_connections || s->connections < s->max_connections) {
  69         qio_net_listener_set_client_func(s->listener, nbd_accept, NULL, NULL);
  70     } else {
  71         qio_net_listener_set_client_func(s->listener, NULL, NULL, NULL);
  72     }
  73 }
  74
  75 static void nbd_server_free(NBDServerData *server)
  76 {
  77     if (!server) {
  78         return;
  79     }
  80
  81     qio_net_listener_disconnect(server->listener);
  82     object_unref(OBJECT(server->listener));
  83     if (server->tlscreds) {
  84         object_unref(OBJECT(server->tlscreds));
  85     }
  86     g_free(server->tlsauthz);
  87
  88     g_free(server);
  89 }
  90
  91 static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp)
  92 {
  93     Object *obj;
  94     QCryptoTLSCreds *creds;
  95
  96     obj = object_resolve_path_component(
  97         object_get_objects_root(), id);
  98     if (!obj) {
  99         error_setg(errp, "No TLS credentials with id '%s'",
 100                    id);
 101         return NULL;
 102     }
 103     creds = (QCryptoTLSCreds *)
 104         object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS);
 105     if (!creds) {
 106         error_setg(errp, "Object with id '%s' is not TLS credentials",
 107                    id);
 108         return NULL;
 109     }
 110
 111     if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
 112         error_setg(errp,
 113                    "Expecting TLS credentials with a server endpoint");
 114         return NULL;
 115     }
 116     object_ref(obj);
 117     return creds;
 118 }
 119
 120
 121 void nbd_server_start(SocketAddress *addr, const char *tls_creds,
 122                       const char *tls_authz, uint32_t max_connections,
 123                       Error **errp)
 124 {
 125     if (nbd_server) {
 126         error_setg(errp, "NBD server already running");
 127         return;
 128     }
 129
 130     nbd_server = g_new0(NBDServerData, 1);
 131     nbd_server->max_connections = max_connections;
 132     nbd_server->listener = qio_net_listener_new();
 133
 134     qio_net_listener_set_name(nbd_server->listener,
 135                               "nbd-listener");
 136
 137     /*
 138      * Because this server is persistent, a backlog of SOMAXCONN is
 139      * better than trying to size it to max_connections.
 140      */
 141     if (qio_net_listener_open_sync(nbd_server->listener, addr, SOMAXCONN,
 142                                    errp) < 0) {
 143         goto error;
 144     }
 145
 146     if (tls_creds) {
 147         nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp);
 148         if (!nbd_server->tlscreds) {
 149             goto error;
 150         }
 151
 152         /* TODO SOCKET_ADDRESS_TYPE_FD where fd has AF_INET or AF_INET6 */
 153         if (addr->type != SOCKET_ADDRESS_TYPE_INET) {
 154             error_setg(errp, "TLS is only supported with IPv4/IPv6");
 155             goto error;
 156         }
 157     }
 158
 159     nbd_server->tlsauthz = g_strdup(tls_authz);
 160
 161     nbd_update_server_watch(nbd_server);
 162
 163     return;
 164
 165  error:
 166     nbd_server_free(nbd_server);
 167     nbd_server = NULL;
 168 }
 169
 170 void nbd_server_start_options(NbdServerOptions *arg, Error **errp)
 171 {
 172     nbd_server_start(arg->addr, arg->tls_creds, arg->tls_authz,
 173                      arg->max_connections, errp);
 174 }
 175
 176 void qmp_nbd_server_start(SocketAddressLegacy *addr,
 177                           bool has_tls_creds, const char *tls_creds,
 178                           bool has_tls_authz, const char *tls_authz,
 179                           bool has_max_connections, uint32_t max_connections,
 180                           Error **errp)
 181 {
 182     SocketAddress *addr_flat = socket_address_flatten(addr);
 183
 184     nbd_server_start(addr_flat, tls_creds, tls_authz, max_connections, errp);
 185     qapi_free_SocketAddress(addr_flat);
 186 }
 187
 188 void qmp_nbd_server_add(NbdServerAddOptions *arg, Error **errp)
 189 {
 190     BlockExport *export;
 191     BlockDriverState *bs;
 192     BlockBackend *on_eject_blk;
 193     BlockExportOptions *export_opts;
 194
 195     bs = bdrv_lookup_bs(arg->device, arg->device, errp);
 196     if (!bs) {
 197         return;
 198     }
 199
 200     /*
 201      * block-export-add would default to the node-name, but we may have to use
 202      * the device name as a default here for compatibility.
 203      */
 204     if (!arg->has_name) {
 205         arg->has_name = true;
 206         arg->name = g_strdup(arg->device);
 207     }
 208
 209     export_opts = g_new(BlockExportOptions, 1);
 210     *export_opts = (BlockExportOptions) {
 211         .type                   = BLOCK_EXPORT_TYPE_NBD,
 212         .id                     = g_strdup(arg->name),
 213         .node_name              = g_strdup(bdrv_get_node_name(bs)),
 214         .has_writable           = arg->has_writable,
 215         .writable               = arg->writable,
 216     };
 217     QAPI_CLONE_MEMBERS(BlockExportOptionsNbdBase, &export_opts->u.nbd,
 218                        qapi_NbdServerAddOptions_base(arg));
 219     if (arg->has_bitmap) {
 220         export_opts->u.nbd.has_bitmaps = true;
 221         QAPI_LIST_PREPEND(export_opts->u.nbd.bitmaps, g_strdup(arg->bitmap));
 222     }
 223
 224     /*
 225      * nbd-server-add doesn't complain when a read-only device should be
 226      * exported as writable, but simply downgrades it. This is an error with
 227      * block-export-add.
 228      */
 229     if (bdrv_is_read_only(bs)) {
 230         export_opts->has_writable = true;
 231         export_opts->writable = false;
 232     }
 233
 234     export = blk_exp_add(export_opts, errp);
 235     if (!export) {
 236         goto fail;
 237     }
 238
 239     /*
 240      * nbd-server-add removes the export when the named BlockBackend used for
 241      * @device goes away.
 242      */
 243     on_eject_blk = blk_by_name(arg->device);
 244     if (on_eject_blk) {
 245         nbd_export_set_on_eject_blk(export, on_eject_blk);
 246     }
 247
 248 fail:
 249     qapi_free_BlockExportOptions(export_opts);
 250 }
 251
 252 void qmp_nbd_server_remove(const char *name,
 253                            bool has_mode, BlockExportRemoveMode mode,
 254                            Error **errp)
 255 {
 256     BlockExport *exp;
 257
 258     exp = blk_exp_find(name);
 259     if (exp && exp->drv->type != BLOCK_EXPORT_TYPE_NBD) {
 260         error_setg(errp, "Block export '%s' is not an NBD export", name);
 261         return;
 262     }
 263
 264     qmp_block_export_del(name, has_mode, mode, errp);
 265 }
 266
 267 void qmp_nbd_server_stop(Error **errp)
 268 {
 269     if (!nbd_server) {
 270         error_setg(errp, "NBD server not running");
 271         return;
 272     }
 273
 274     blk_exp_close_all_type(BLOCK_EXPORT_TYPE_NBD);
 275
 276     nbd_server_free(nbd_server);
 277     nbd_server = NULL;
 278 }