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 32 static void nbd_update_server_watch(NBDServerData *s); 33 34 static void nbd_blockdev_client_closed(NBDClient *client, bool ignored) 35 { 36 nbd_client_put(client); 37 assert(nbd_server->connections > 0); 38 nbd_server->connections--; 39 nbd_update_server_watch(nbd_server); 40 } 41 42 static void nbd_accept(QIONetListener *listener, QIOChannelSocket *cioc, 43 gpointer opaque) 44 { 45 nbd_server->connections++; 46 nbd_update_server_watch(nbd_server); 47 48 qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server"); 49 nbd_client_new(cioc, nbd_server->tlscreds, nbd_server->tlsauthz, 50 nbd_blockdev_client_closed); 51 } 52 53 static void nbd_update_server_watch(NBDServerData *s) 54 { 55 if (!s->max_connections || s->connections < s->max_connections) { 56 qio_net_listener_set_client_func(s->listener, nbd_accept, NULL, NULL); 57 } else { 58 qio_net_listener_set_client_func(s->listener, NULL, NULL, NULL); 59 } 60 } 61 62 static void nbd_server_free(NBDServerData *server) 63 { 64 if (!server) { 65 return; 66 } 67 68 qio_net_listener_disconnect(server->listener); 69 object_unref(OBJECT(server->listener)); 70 if (server->tlscreds) { 71 object_unref(OBJECT(server->tlscreds)); 72 } 73 g_free(server->tlsauthz); 74 75 g_free(server); 76 } 77 78 static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp) 79 { 80 Object *obj; 81 QCryptoTLSCreds *creds; 82 83 obj = object_resolve_path_component( 84 object_get_objects_root(), id); 85 if (!obj) { 86 error_setg(errp, "No TLS credentials with id '%s'", 87 id); 88 return NULL; 89 } 90 creds = (QCryptoTLSCreds *) 91 object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS); 92 if (!creds) { 93 error_setg(errp, "Object with id '%s' is not TLS credentials", 94 id); 95 return NULL; 96 } 97 98 if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) { 99 error_setg(errp, 100 "Expecting TLS credentials with a server endpoint"); 101 return NULL; 102 } 103 object_ref(obj); 104 return creds; 105 } 106 107 108 void nbd_server_start(SocketAddress *addr, const char *tls_creds, 109 const char *tls_authz, uint32_t max_connections, 110 Error **errp) 111 { 112 if (nbd_server) { 113 error_setg(errp, "NBD server already running"); 114 return; 115 } 116 117 nbd_server = g_new0(NBDServerData, 1); 118 nbd_server->max_connections = max_connections; 119 nbd_server->listener = qio_net_listener_new(); 120 121 qio_net_listener_set_name(nbd_server->listener, 122 "nbd-listener"); 123 124 if (qio_net_listener_open_sync(nbd_server->listener, addr, 1, errp) < 0) { 125 goto error; 126 } 127 128 if (tls_creds) { 129 nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp); 130 if (!nbd_server->tlscreds) { 131 goto error; 132 } 133 134 /* TODO SOCKET_ADDRESS_TYPE_FD where fd has AF_INET or AF_INET6 */ 135 if (addr->type != SOCKET_ADDRESS_TYPE_INET) { 136 error_setg(errp, "TLS is only supported with IPv4/IPv6"); 137 goto error; 138 } 139 } 140 141 nbd_server->tlsauthz = g_strdup(tls_authz); 142 143 nbd_update_server_watch(nbd_server); 144 145 return; 146 147 error: 148 nbd_server_free(nbd_server); 149 nbd_server = NULL; 150 } 151 152 void nbd_server_start_options(NbdServerOptions *arg, Error **errp) 153 { 154 nbd_server_start(arg->addr, arg->tls_creds, arg->tls_authz, 155 arg->max_connections, errp); 156 } 157 158 void qmp_nbd_server_start(SocketAddressLegacy *addr, 159 bool has_tls_creds, const char *tls_creds, 160 bool has_tls_authz, const char *tls_authz, 161 bool has_max_connections, uint32_t max_connections, 162 Error **errp) 163 { 164 SocketAddress *addr_flat = socket_address_flatten(addr); 165 166 nbd_server_start(addr_flat, tls_creds, tls_authz, max_connections, errp); 167 qapi_free_SocketAddress(addr_flat); 168 } 169 170 BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp) 171 { 172 BlockExportOptionsNbd *arg = &exp_args->u.nbd; 173 BlockDriverState *bs = NULL; 174 NBDExport *exp = NULL; 175 AioContext *aio_context; 176 177 assert(exp_args->type == BLOCK_EXPORT_TYPE_NBD); 178 179 if (!nbd_server) { 180 error_setg(errp, "NBD server not running"); 181 return NULL; 182 } 183 184 if (!arg->has_name) { 185 arg->name = arg->device; 186 } 187 188 if (strlen(arg->name) > NBD_MAX_STRING_SIZE) { 189 error_setg(errp, "export name '%s' too long", arg->name); 190 return NULL; 191 } 192 193 if (arg->description && strlen(arg->description) > NBD_MAX_STRING_SIZE) { 194 error_setg(errp, "description '%s' too long", arg->description); 195 return NULL; 196 } 197 198 if (nbd_export_find(arg->name)) { 199 error_setg(errp, "NBD server already has export named '%s'", arg->name); 200 return NULL; 201 } 202 203 bs = bdrv_lookup_bs(arg->device, arg->device, errp); 204 if (!bs) { 205 return NULL; 206 } 207 208 aio_context = bdrv_get_aio_context(bs); 209 aio_context_acquire(aio_context); 210 211 if (!arg->has_writable) { 212 arg->writable = false; 213 } 214 if (bdrv_is_read_only(bs) && arg->writable) { 215 error_setg(errp, "Cannot export read-only node as writable"); 216 goto out; 217 } 218 219 if (!exp_args->has_writethrough) { 220 exp_args->writethrough = false; 221 } 222 223 exp = nbd_export_new(bs, arg->name, arg->description, arg->bitmap, 224 !arg->writable, !arg->writable, 225 NULL, exp_args->writethrough, errp); 226 if (!exp) { 227 goto out; 228 } 229 230 /* The list of named exports has a strong reference to this export now and 231 * our only way of accessing it is through nbd_export_find(), so we can drop 232 * the strong reference that is @exp. */ 233 nbd_export_put(exp); 234 235 out: 236 aio_context_release(aio_context); 237 /* TODO Remove the cast: nbd_export_new() will return a BlockExport. */ 238 return (BlockExport*) exp; 239 } 240 241 void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp) 242 { 243 BlockExport *export; 244 BlockDriverState *bs; 245 BlockBackend *on_eject_blk; 246 BlockExportOptions export_opts; 247 248 bs = bdrv_lookup_bs(arg->device, arg->device, errp); 249 if (!bs) { 250 return; 251 } 252 253 export_opts = (BlockExportOptions) { 254 .type = BLOCK_EXPORT_TYPE_NBD, 255 .u.nbd = *arg, 256 }; 257 258 /* 259 * nbd-server-add doesn't complain when a read-only device should be 260 * exported as writable, but simply downgrades it. This is an error with 261 * block-export-add. 262 */ 263 if (bdrv_is_read_only(bs)) { 264 export_opts.u.nbd.has_writable = true; 265 export_opts.u.nbd.writable = false; 266 } 267 268 export = blk_exp_add(&export_opts, errp); 269 if (!export) { 270 return; 271 } 272 273 /* 274 * nbd-server-add removes the export when the named BlockBackend used for 275 * @device goes away. 276 */ 277 on_eject_blk = blk_by_name(arg->device); 278 if (on_eject_blk) { 279 nbd_export_set_on_eject_blk(export, on_eject_blk); 280 } 281 } 282 283 void qmp_nbd_server_remove(const char *name, 284 bool has_mode, NbdServerRemoveMode mode, 285 Error **errp) 286 { 287 NBDExport *exp; 288 AioContext *aio_context; 289 290 if (!nbd_server) { 291 error_setg(errp, "NBD server not running"); 292 return; 293 } 294 295 exp = nbd_export_find(name); 296 if (exp == NULL) { 297 error_setg(errp, "Export '%s' is not found", name); 298 return; 299 } 300 301 if (!has_mode) { 302 mode = NBD_SERVER_REMOVE_MODE_SAFE; 303 } 304 305 aio_context = nbd_export_aio_context(exp); 306 aio_context_acquire(aio_context); 307 nbd_export_remove(exp, mode, errp); 308 aio_context_release(aio_context); 309 } 310 311 void qmp_nbd_server_stop(Error **errp) 312 { 313 if (!nbd_server) { 314 error_setg(errp, "NBD server not running"); 315 return; 316 } 317 318 nbd_export_close_all(); 319 320 nbd_server_free(nbd_server); 321 nbd_server = NULL; 322 } 323