/* * Serving QEMU block devices via NBD * * Copyright (c) 2012 Red Hat, Inc. * * Author: Paolo Bonzini <pbonzini@redhat.com> * * This work is licensed under the terms of the GNU GPL, version 2 or * later. See the COPYING file in the top-level directory. */ #include "qemu/osdep.h" #include "sysemu/blockdev.h" #include "sysemu/block-backend.h" #include "hw/block/block.h" #include "qapi/error.h" #include "qapi/clone-visitor.h" #include "qapi/qapi-visit-block-export.h" #include "qapi/qapi-commands-block-export.h" #include "block/nbd.h" #include "io/channel-socket.h" #include "io/net-listener.h" typedef struct NBDServerData { QIONetListener *listener; QCryptoTLSCreds *tlscreds; char *tlsauthz; uint32_t max_connections; uint32_t connections; } NBDServerData; static NBDServerData *nbd_server; static int qemu_nbd_connections = -1; /* Non-negative if this is qemu-nbd */ static void nbd_update_server_watch(NBDServerData *s); void nbd_server_is_qemu_nbd(int max_connections) { qemu_nbd_connections = max_connections; } bool nbd_server_is_running(void) { return nbd_server || qemu_nbd_connections >= 0; } int nbd_server_max_connections(void) { return nbd_server ? nbd_server->max_connections : qemu_nbd_connections; } static void nbd_blockdev_client_closed(NBDClient *client, bool ignored) { nbd_client_put(client); assert(nbd_server->connections > 0); nbd_server->connections--; nbd_update_server_watch(nbd_server); } static void nbd_accept(QIONetListener *listener, QIOChannelSocket *cioc, gpointer opaque) { nbd_server->connections++; nbd_update_server_watch(nbd_server); qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server"); nbd_client_new(cioc, nbd_server->tlscreds, nbd_server->tlsauthz, nbd_blockdev_client_closed); } static void nbd_update_server_watch(NBDServerData *s) { if (!s->max_connections || s->connections < s->max_connections) { qio_net_listener_set_client_func(s->listener, nbd_accept, NULL, NULL); } else { qio_net_listener_set_client_func(s->listener, NULL, NULL, NULL); } } static void nbd_server_free(NBDServerData *server) { if (!server) { return; } qio_net_listener_disconnect(server->listener); object_unref(OBJECT(server->listener)); if (server->tlscreds) { object_unref(OBJECT(server->tlscreds)); } g_free(server->tlsauthz); g_free(server); } static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp) { Object *obj; QCryptoTLSCreds *creds; obj = object_resolve_path_component( object_get_objects_root(), id); if (!obj) { error_setg(errp, "No TLS credentials with id '%s'", id); return NULL; } creds = (QCryptoTLSCreds *) object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS); if (!creds) { error_setg(errp, "Object with id '%s' is not TLS credentials", id); return NULL; } if (!qcrypto_tls_creds_check_endpoint(creds, QCRYPTO_TLS_CREDS_ENDPOINT_SERVER, errp)) { return NULL; } object_ref(obj); return creds; } void nbd_server_start(SocketAddress *addr, const char *tls_creds, const char *tls_authz, uint32_t max_connections, Error **errp) { if (nbd_server) { error_setg(errp, "NBD server already running"); return; } nbd_server = g_new0(NBDServerData, 1); nbd_server->max_connections = max_connections; nbd_server->listener = qio_net_listener_new(); qio_net_listener_set_name(nbd_server->listener, "nbd-listener"); /* * Because this server is persistent, a backlog of SOMAXCONN is * better than trying to size it to max_connections. */ if (qio_net_listener_open_sync(nbd_server->listener, addr, SOMAXCONN, errp) < 0) { goto error; } if (tls_creds) { nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp); if (!nbd_server->tlscreds) { goto error; } } nbd_server->tlsauthz = g_strdup(tls_authz); nbd_update_server_watch(nbd_server); return; error: nbd_server_free(nbd_server); nbd_server = NULL; } void nbd_server_start_options(NbdServerOptions *arg, Error **errp) { nbd_server_start(arg->addr, arg->tls_creds, arg->tls_authz, arg->max_connections, errp); } void qmp_nbd_server_start(SocketAddressLegacy *addr, const char *tls_creds, const char *tls_authz, bool has_max_connections, uint32_t max_connections, Error **errp) { SocketAddress *addr_flat = socket_address_flatten(addr); nbd_server_start(addr_flat, tls_creds, tls_authz, max_connections, errp); qapi_free_SocketAddress(addr_flat); } void qmp_nbd_server_add(NbdServerAddOptions *arg, Error **errp) { BlockExport *export; BlockDriverState *bs; BlockBackend *on_eject_blk; BlockExportOptions *export_opts; bs = bdrv_lookup_bs(arg->device, arg->device, errp); if (!bs) { return; } /* * block-export-add would default to the node-name, but we may have to use * the device name as a default here for compatibility. */ if (!arg->name) { arg->name = g_strdup(arg->device); } export_opts = g_new(BlockExportOptions, 1); *export_opts = (BlockExportOptions) { .type = BLOCK_EXPORT_TYPE_NBD, .id = g_strdup(arg->name), .node_name = g_strdup(bdrv_get_node_name(bs)), .has_writable = arg->has_writable, .writable = arg->writable, }; QAPI_CLONE_MEMBERS(BlockExportOptionsNbdBase, &export_opts->u.nbd, qapi_NbdServerAddOptions_base(arg)); if (arg->bitmap) { BlockDirtyBitmapOrStr *el = g_new(BlockDirtyBitmapOrStr, 1); *el = (BlockDirtyBitmapOrStr) { .type = QTYPE_QSTRING, .u.local = g_strdup(arg->bitmap), }; export_opts->u.nbd.has_bitmaps = true; QAPI_LIST_PREPEND(export_opts->u.nbd.bitmaps, el); } /* * nbd-server-add doesn't complain when a read-only device should be * exported as writable, but simply downgrades it. This is an error with * block-export-add. */ if (bdrv_is_read_only(bs)) { export_opts->has_writable = true; export_opts->writable = false; } export = blk_exp_add(export_opts, errp); if (!export) { goto fail; } /* * nbd-server-add removes the export when the named BlockBackend used for * @device goes away. */ on_eject_blk = blk_by_name(arg->device); if (on_eject_blk) { nbd_export_set_on_eject_blk(export, on_eject_blk); } fail: qapi_free_BlockExportOptions(export_opts); } void qmp_nbd_server_remove(const char *name, bool has_mode, BlockExportRemoveMode mode, Error **errp) { BlockExport *exp; exp = blk_exp_find(name); if (exp && exp->drv->type != BLOCK_EXPORT_TYPE_NBD) { error_setg(errp, "Block export '%s' is not an NBD export", name); return; } qmp_block_export_del(name, has_mode, mode, errp); } void qmp_nbd_server_stop(Error **errp) { if (!nbd_server) { error_setg(errp, "NBD server not running"); return; } blk_exp_close_all_type(BLOCK_EXPORT_TYPE_NBD); nbd_server_free(nbd_server); nbd_server = NULL; }