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 "system/blockdev.h" 14 #include "system/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 NBDConn { 25 QIOChannelSocket *cioc; 26 QLIST_ENTRY(NBDConn) next; 27 } NBDConn; 28 29 typedef struct NBDServerData { 30 QIONetListener *listener; 31 uint32_t handshake_max_secs; 32 QCryptoTLSCreds *tlscreds; 33 char *tlsauthz; 34 uint32_t max_connections; 35 uint32_t connections; 36 QLIST_HEAD(, NBDConn) conns; 37 } NBDServerData; 38 39 static NBDServerData *nbd_server; 40 static int qemu_nbd_connections = -1; /* Non-negative if this is qemu-nbd */ 41 42 static void nbd_update_server_watch(NBDServerData *s); 43 44 void nbd_server_is_qemu_nbd(int max_connections) 45 { 46 qemu_nbd_connections = max_connections; 47 } 48 49 bool nbd_server_is_running(void) 50 { 51 return nbd_server || qemu_nbd_connections >= 0; 52 } 53 54 int nbd_server_max_connections(void) 55 { 56 return nbd_server ? nbd_server->max_connections : qemu_nbd_connections; 57 } 58 59 static void nbd_blockdev_client_closed(NBDClient *client, bool ignored) 60 { 61 NBDConn *conn = nbd_client_owner(client); 62 63 assert(qemu_in_main_thread() && nbd_server); 64 65 object_unref(OBJECT(conn->cioc)); 66 QLIST_REMOVE(conn, next); 67 g_free(conn); 68 69 nbd_client_put(client); 70 assert(nbd_server->connections > 0); 71 nbd_server->connections--; 72 nbd_update_server_watch(nbd_server); 73 } 74 75 static void nbd_accept(QIONetListener *listener, QIOChannelSocket *cioc, 76 gpointer opaque) 77 { 78 NBDConn *conn = g_new0(NBDConn, 1); 79 80 assert(qemu_in_main_thread() && nbd_server); 81 nbd_server->connections++; 82 object_ref(OBJECT(cioc)); 83 conn->cioc = cioc; 84 QLIST_INSERT_HEAD(&nbd_server->conns, conn, next); 85 nbd_update_server_watch(nbd_server); 86 87 qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server"); 88 nbd_client_new(cioc, nbd_server->handshake_max_secs, 89 nbd_server->tlscreds, nbd_server->tlsauthz, 90 nbd_blockdev_client_closed, conn); 91 } 92 93 static void nbd_update_server_watch(NBDServerData *s) 94 { 95 if (s->listener) { 96 if (!s->max_connections || s->connections < s->max_connections) { 97 qio_net_listener_set_client_func(s->listener, nbd_accept, NULL, 98 NULL); 99 } else { 100 qio_net_listener_set_client_func(s->listener, NULL, NULL, NULL); 101 } 102 } 103 } 104 105 static void nbd_server_free(NBDServerData *server) 106 { 107 NBDConn *conn, *tmp; 108 109 if (!server) { 110 return; 111 } 112 113 /* 114 * Forcefully close the listener socket, and any clients that have 115 * not yet disconnected on their own. 116 */ 117 qio_net_listener_disconnect(server->listener); 118 object_unref(OBJECT(server->listener)); 119 server->listener = NULL; 120 QLIST_FOREACH_SAFE(conn, &server->conns, next, tmp) { 121 qio_channel_shutdown(QIO_CHANNEL(conn->cioc), QIO_CHANNEL_SHUTDOWN_BOTH, 122 NULL); 123 } 124 125 AIO_WAIT_WHILE_UNLOCKED(NULL, server->connections > 0); 126 127 if (server->tlscreds) { 128 object_unref(OBJECT(server->tlscreds)); 129 } 130 g_free(server->tlsauthz); 131 132 g_free(server); 133 } 134 135 static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp) 136 { 137 Object *obj; 138 QCryptoTLSCreds *creds; 139 140 obj = object_resolve_path_component( 141 object_get_objects_root(), id); 142 if (!obj) { 143 error_setg(errp, "No TLS credentials with id '%s'", 144 id); 145 return NULL; 146 } 147 creds = (QCryptoTLSCreds *) 148 object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS); 149 if (!creds) { 150 error_setg(errp, "Object with id '%s' is not TLS credentials", 151 id); 152 return NULL; 153 } 154 155 if (!qcrypto_tls_creds_check_endpoint(creds, 156 QCRYPTO_TLS_CREDS_ENDPOINT_SERVER, 157 errp)) { 158 return NULL; 159 } 160 object_ref(obj); 161 return creds; 162 } 163 164 165 void nbd_server_start(SocketAddress *addr, uint32_t handshake_max_secs, 166 const char *tls_creds, const char *tls_authz, 167 uint32_t max_connections, Error **errp) 168 { 169 if (nbd_server) { 170 error_setg(errp, "NBD server already running"); 171 return; 172 } 173 174 nbd_server = g_new0(NBDServerData, 1); 175 nbd_server->max_connections = max_connections; 176 nbd_server->handshake_max_secs = handshake_max_secs; 177 nbd_server->listener = qio_net_listener_new(); 178 179 qio_net_listener_set_name(nbd_server->listener, 180 "nbd-listener"); 181 182 /* 183 * Because this server is persistent, a backlog of SOMAXCONN is 184 * better than trying to size it to max_connections. 185 */ 186 if (qio_net_listener_open_sync(nbd_server->listener, addr, SOMAXCONN, 187 errp) < 0) { 188 goto error; 189 } 190 191 if (tls_creds) { 192 nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp); 193 if (!nbd_server->tlscreds) { 194 goto error; 195 } 196 } 197 198 nbd_server->tlsauthz = g_strdup(tls_authz); 199 200 nbd_update_server_watch(nbd_server); 201 202 return; 203 204 error: 205 nbd_server_free(nbd_server); 206 nbd_server = NULL; 207 } 208 209 void nbd_server_start_options(NbdServerOptions *arg, Error **errp) 210 { 211 if (!arg->has_max_connections) { 212 arg->max_connections = NBD_DEFAULT_MAX_CONNECTIONS; 213 } 214 if (!arg->has_handshake_max_seconds) { 215 arg->handshake_max_seconds = NBD_DEFAULT_HANDSHAKE_MAX_SECS; 216 } 217 218 nbd_server_start(arg->addr, arg->handshake_max_seconds, arg->tls_creds, 219 arg->tls_authz, arg->max_connections, errp); 220 } 221 222 void qmp_nbd_server_start(SocketAddressLegacy *addr, 223 bool has_handshake_max_secs, 224 uint32_t handshake_max_secs, 225 const char *tls_creds, 226 const char *tls_authz, 227 bool has_max_connections, uint32_t max_connections, 228 Error **errp) 229 { 230 SocketAddress *addr_flat = socket_address_flatten(addr); 231 232 if (!has_max_connections) { 233 max_connections = NBD_DEFAULT_MAX_CONNECTIONS; 234 } 235 if (!has_handshake_max_secs) { 236 handshake_max_secs = NBD_DEFAULT_HANDSHAKE_MAX_SECS; 237 } 238 239 nbd_server_start(addr_flat, handshake_max_secs, tls_creds, tls_authz, 240 max_connections, errp); 241 qapi_free_SocketAddress(addr_flat); 242 } 243 244 void qmp_nbd_server_add(NbdServerAddOptions *arg, Error **errp) 245 { 246 BlockExport *export; 247 BlockDriverState *bs; 248 BlockBackend *on_eject_blk; 249 BlockExportOptions *export_opts; 250 251 bs = bdrv_lookup_bs(arg->device, arg->device, errp); 252 if (!bs) { 253 return; 254 } 255 256 /* 257 * block-export-add would default to the node-name, but we may have to use 258 * the device name as a default here for compatibility. 259 */ 260 if (!arg->name) { 261 arg->name = g_strdup(arg->device); 262 } 263 264 export_opts = g_new(BlockExportOptions, 1); 265 *export_opts = (BlockExportOptions) { 266 .type = BLOCK_EXPORT_TYPE_NBD, 267 .id = g_strdup(arg->name), 268 .node_name = g_strdup(bdrv_get_node_name(bs)), 269 .has_writable = arg->has_writable, 270 .writable = arg->writable, 271 }; 272 QAPI_CLONE_MEMBERS(BlockExportOptionsNbdBase, &export_opts->u.nbd, 273 qapi_NbdServerAddOptions_base(arg)); 274 if (arg->bitmap) { 275 BlockDirtyBitmapOrStr *el = g_new(BlockDirtyBitmapOrStr, 1); 276 277 *el = (BlockDirtyBitmapOrStr) { 278 .type = QTYPE_QSTRING, 279 .u.local = g_strdup(arg->bitmap), 280 }; 281 export_opts->u.nbd.has_bitmaps = true; 282 QAPI_LIST_PREPEND(export_opts->u.nbd.bitmaps, el); 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->has_writable = true; 292 export_opts->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, BlockExportRemoveMode mode, 315 Error **errp) 316 { 317 BlockExport *exp; 318 319 exp = blk_exp_find(name); 320 if (exp && exp->drv->type != BLOCK_EXPORT_TYPE_NBD) { 321 error_setg(errp, "Block export '%s' is not an NBD export", name); 322 return; 323 } 324 325 qmp_block_export_del(name, has_mode, mode, errp); 326 } 327 328 void qmp_nbd_server_stop(Error **errp) 329 { 330 if (!nbd_server) { 331 error_setg(errp, "NBD server not running"); 332 return; 333 } 334 335 blk_exp_close_all_type(BLOCK_EXPORT_TYPE_NBD); 336 337 nbd_server_free(nbd_server); 338 nbd_server = NULL; 339 } 340