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/qmp/qerror.h"
  17 #include "sysemu/sysemu.h"
  18 #include "qmp-commands.h"
  19 #include "block/nbd.h"
  20 #include "io/channel-socket.h"
  21 #include "io/net-listener.h"
  22
  23 typedef struct NBDServerData {
  24     QIONetListener *listener;
  25     QCryptoTLSCreds *tlscreds;
  26 } NBDServerData;
  27
  28 static NBDServerData *nbd_server;
  29
  30 static void nbd_blockdev_client_closed(NBDClient *client, bool ignored)
  31 {
  32     nbd_client_put(client);
  33 }
  34
  35 static void nbd_accept(QIONetListener *listener, QIOChannelSocket *cioc,
  36                        gpointer opaque)
  37 {
  38     qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server");
  39     nbd_client_new(NULL, cioc,
  40                    nbd_server->tlscreds, NULL,
  41                    nbd_blockdev_client_closed);
  42 }
  43
  44
  45 static void nbd_server_free(NBDServerData *server)
  46 {
  47     if (!server) {
  48         return;
  49     }
  50
  51     qio_net_listener_disconnect(server->listener);
  52     object_unref(OBJECT(server->listener));
  53     if (server->tlscreds) {
  54         object_unref(OBJECT(server->tlscreds));
  55     }
  56
  57     g_free(server);
  58 }
  59
  60 static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp)
  61 {
  62     Object *obj;
  63     QCryptoTLSCreds *creds;
  64
  65     obj = object_resolve_path_component(
  66         object_get_objects_root(), id);
  67     if (!obj) {
  68         error_setg(errp, "No TLS credentials with id '%s'",
  69                    id);
  70         return NULL;
  71     }
  72     creds = (QCryptoTLSCreds *)
  73         object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS);
  74     if (!creds) {
  75         error_setg(errp, "Object with id '%s' is not TLS credentials",
  76                    id);
  77         return NULL;
  78     }
  79
  80     if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
  81         error_setg(errp,
  82                    "Expecting TLS credentials with a server endpoint");
  83         return NULL;
  84     }
  85     object_ref(obj);
  86     return creds;
  87 }
  88
  89
  90 void nbd_server_start(SocketAddress *addr, const char *tls_creds,
  91                       Error **errp)
  92 {
  93     if (nbd_server) {
  94         error_setg(errp, "NBD server already running");
  95         return;
  96     }
  97
  98     nbd_server = g_new0(NBDServerData, 1);
  99     nbd_server->listener = qio_net_listener_new();
 100
 101     qio_net_listener_set_name(nbd_server->listener,
 102                               "nbd-listener");
 103
 104     if (qio_net_listener_open_sync(nbd_server->listener, addr, errp) < 0) {
 105         goto error;
 106     }
 107
 108     if (tls_creds) {
 109         nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp);
 110         if (!nbd_server->tlscreds) {
 111             goto error;
 112         }
 113
 114         /* TODO SOCKET_ADDRESS_TYPE_FD where fd has AF_INET or AF_INET6 */
 115         if (addr->type != SOCKET_ADDRESS_TYPE_INET) {
 116             error_setg(errp, "TLS is only supported with IPv4/IPv6");
 117             goto error;
 118         }
 119     }
 120
 121     qio_net_listener_set_client_func(nbd_server->listener,
 122                                      nbd_accept,
 123                                      NULL,
 124                                      NULL);
 125
 126     return;
 127
 128  error:
 129     nbd_server_free(nbd_server);
 130     nbd_server = NULL;
 131 }
 132
 133 void qmp_nbd_server_start(SocketAddressLegacy *addr,
 134                           bool has_tls_creds, const char *tls_creds,
 135                           Error **errp)
 136 {
 137     SocketAddress *addr_flat = socket_address_flatten(addr);
 138
 139     nbd_server_start(addr_flat, tls_creds, errp);
 140     qapi_free_SocketAddress(addr_flat);
 141 }
 142
 143 void qmp_nbd_server_add(const char *device, bool has_writable, bool writable,
 144                         Error **errp)
 145 {
 146     BlockDriverState *bs = NULL;
 147     BlockBackend *on_eject_blk;
 148     NBDExport *exp;
 149
 150     if (!nbd_server) {
 151         error_setg(errp, "NBD server not running");
 152         return;
 153     }
 154
 155     if (nbd_export_find(device)) {
 156         error_setg(errp, "NBD server already exporting device '%s'", device);
 157         return;
 158     }
 159
 160     on_eject_blk = blk_by_name(device);
 161
 162     bs = bdrv_lookup_bs(device, device, errp);
 163     if (!bs) {
 164         return;
 165     }
 166
 167     if (!has_writable) {
 168         writable = false;
 169     }
 170     if (bdrv_is_read_only(bs)) {
 171         writable = false;
 172     }
 173
 174     exp = nbd_export_new(bs, 0, -1, writable ? 0 : NBD_FLAG_READ_ONLY,
 175                          NULL, false, on_eject_blk, errp);
 176     if (!exp) {
 177         return;
 178     }
 179
 180     nbd_export_set_name(exp, device);
 181
 182     /* The list of named exports has a strong reference to this export now and
 183      * our only way of accessing it is through nbd_export_find(), so we can drop
 184      * the strong reference that is @exp. */
 185     nbd_export_put(exp);
 186 }
 187
 188 void qmp_nbd_server_stop(Error **errp)
 189 {
 190     nbd_export_close_all();
 191
 192     nbd_server_free(nbd_server);
 193     nbd_server = NULL;
 194 }