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