blockdev-nbd.c (7892B)
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 int qemu_nbd_connections = -1; /* Non-negative if this is qemu-nbd */ 34 35 static void nbd_update_server_watch(NBDServerData *s); 36 37 void nbd_server_is_qemu_nbd(int max_connections) 38 { 39 qemu_nbd_connections = max_connections; 40 } 41 42 bool nbd_server_is_running(void) 43 { 44 return nbd_server || qemu_nbd_connections >= 0; 45 } 46 47 int nbd_server_max_connections(void) 48 { 49 return nbd_server ? nbd_server->max_connections : qemu_nbd_connections; 50 } 51 52 static void nbd_blockdev_client_closed(NBDClient *client, bool ignored) 53 { 54 nbd_client_put(client); 55 assert(nbd_server->connections > 0); 56 nbd_server->connections--; 57 nbd_update_server_watch(nbd_server); 58 } 59 60 static void nbd_accept(QIONetListener *listener, QIOChannelSocket *cioc, 61 gpointer opaque) 62 { 63 nbd_server->connections++; 64 nbd_update_server_watch(nbd_server); 65 66 qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server"); 67 nbd_client_new(cioc, nbd_server->tlscreds, nbd_server->tlsauthz, 68 nbd_blockdev_client_closed); 69 } 70 71 static void nbd_update_server_watch(NBDServerData *s) 72 { 73 if (!s->max_connections || s->connections < s->max_connections) { 74 qio_net_listener_set_client_func(s->listener, nbd_accept, NULL, NULL); 75 } else { 76 qio_net_listener_set_client_func(s->listener, NULL, NULL, NULL); 77 } 78 } 79 80 static void nbd_server_free(NBDServerData *server) 81 { 82 if (!server) { 83 return; 84 } 85 86 qio_net_listener_disconnect(server->listener); 87 object_unref(OBJECT(server->listener)); 88 if (server->tlscreds) { 89 object_unref(OBJECT(server->tlscreds)); 90 } 91 g_free(server->tlsauthz); 92 93 g_free(server); 94 } 95 96 static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp) 97 { 98 Object *obj; 99 QCryptoTLSCreds *creds; 100 101 obj = object_resolve_path_component( 102 object_get_objects_root(), id); 103 if (!obj) { 104 error_setg(errp, "No TLS credentials with id '%s'", 105 id); 106 return NULL; 107 } 108 creds = (QCryptoTLSCreds *) 109 object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS); 110 if (!creds) { 111 error_setg(errp, "Object with id '%s' is not TLS credentials", 112 id); 113 return NULL; 114 } 115 116 if (!qcrypto_tls_creds_check_endpoint(creds, 117 QCRYPTO_TLS_CREDS_ENDPOINT_SERVER, 118 errp)) { 119 return NULL; 120 } 121 object_ref(obj); 122 return creds; 123 } 124 125 126 void nbd_server_start(SocketAddress *addr, const char *tls_creds, 127 const char *tls_authz, uint32_t max_connections, 128 Error **errp) 129 { 130 if (nbd_server) { 131 error_setg(errp, "NBD server already running"); 132 return; 133 } 134 135 nbd_server = g_new0(NBDServerData, 1); 136 nbd_server->max_connections = max_connections; 137 nbd_server->listener = qio_net_listener_new(); 138 139 qio_net_listener_set_name(nbd_server->listener, 140 "nbd-listener"); 141 142 /* 143 * Because this server is persistent, a backlog of SOMAXCONN is 144 * better than trying to size it to max_connections. 145 */ 146 if (qio_net_listener_open_sync(nbd_server->listener, addr, SOMAXCONN, 147 errp) < 0) { 148 goto error; 149 } 150 151 if (tls_creds) { 152 nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp); 153 if (!nbd_server->tlscreds) { 154 goto error; 155 } 156 } 157 158 nbd_server->tlsauthz = g_strdup(tls_authz); 159 160 nbd_update_server_watch(nbd_server); 161 162 return; 163 164 error: 165 nbd_server_free(nbd_server); 166 nbd_server = NULL; 167 } 168 169 void nbd_server_start_options(NbdServerOptions *arg, Error **errp) 170 { 171 nbd_server_start(arg->addr, arg->tls_creds, arg->tls_authz, 172 arg->max_connections, errp); 173 } 174 175 void qmp_nbd_server_start(SocketAddressLegacy *addr, 176 bool has_tls_creds, const char *tls_creds, 177 bool has_tls_authz, const char *tls_authz, 178 bool has_max_connections, uint32_t max_connections, 179 Error **errp) 180 { 181 SocketAddress *addr_flat = socket_address_flatten(addr); 182 183 nbd_server_start(addr_flat, tls_creds, tls_authz, max_connections, errp); 184 qapi_free_SocketAddress(addr_flat); 185 } 186 187 void qmp_nbd_server_add(NbdServerAddOptions *arg, Error **errp) 188 { 189 BlockExport *export; 190 BlockDriverState *bs; 191 BlockBackend *on_eject_blk; 192 BlockExportOptions *export_opts; 193 194 bs = bdrv_lookup_bs(arg->device, arg->device, errp); 195 if (!bs) { 196 return; 197 } 198 199 /* 200 * block-export-add would default to the node-name, but we may have to use 201 * the device name as a default here for compatibility. 202 */ 203 if (!arg->has_name) { 204 arg->has_name = true; 205 arg->name = g_strdup(arg->device); 206 } 207 208 export_opts = g_new(BlockExportOptions, 1); 209 *export_opts = (BlockExportOptions) { 210 .type = BLOCK_EXPORT_TYPE_NBD, 211 .id = g_strdup(arg->name), 212 .node_name = g_strdup(bdrv_get_node_name(bs)), 213 .has_writable = arg->has_writable, 214 .writable = arg->writable, 215 }; 216 QAPI_CLONE_MEMBERS(BlockExportOptionsNbdBase, &export_opts->u.nbd, 217 qapi_NbdServerAddOptions_base(arg)); 218 if (arg->has_bitmap) { 219 BlockDirtyBitmapOrStr *el = g_new(BlockDirtyBitmapOrStr, 1); 220 221 *el = (BlockDirtyBitmapOrStr) { 222 .type = QTYPE_QSTRING, 223 .u.local = g_strdup(arg->bitmap), 224 }; 225 export_opts->u.nbd.has_bitmaps = true; 226 QAPI_LIST_PREPEND(export_opts->u.nbd.bitmaps, el); 227 } 228 229 /* 230 * nbd-server-add doesn't complain when a read-only device should be 231 * exported as writable, but simply downgrades it. This is an error with 232 * block-export-add. 233 */ 234 if (bdrv_is_read_only(bs)) { 235 export_opts->has_writable = true; 236 export_opts->writable = false; 237 } 238 239 export = blk_exp_add(export_opts, errp); 240 if (!export) { 241 goto fail; 242 } 243 244 /* 245 * nbd-server-add removes the export when the named BlockBackend used for 246 * @device goes away. 247 */ 248 on_eject_blk = blk_by_name(arg->device); 249 if (on_eject_blk) { 250 nbd_export_set_on_eject_blk(export, on_eject_blk); 251 } 252 253 fail: 254 qapi_free_BlockExportOptions(export_opts); 255 } 256 257 void qmp_nbd_server_remove(const char *name, 258 bool has_mode, BlockExportRemoveMode mode, 259 Error **errp) 260 { 261 BlockExport *exp; 262 263 exp = blk_exp_find(name); 264 if (exp && exp->drv->type != BLOCK_EXPORT_TYPE_NBD) { 265 error_setg(errp, "Block export '%s' is not an NBD export", name); 266 return; 267 } 268 269 qmp_block_export_del(name, has_mode, mode, errp); 270 } 271 272 void qmp_nbd_server_stop(Error **errp) 273 { 274 if (!nbd_server) { 275 error_setg(errp, "NBD server not running"); 276 return; 277 } 278 279 blk_exp_close_all_type(BLOCK_EXPORT_TYPE_NBD); 280 281 nbd_server_free(nbd_server); 282 nbd_server = NULL; 283 }