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
  22 typedef struct NBDServerData {
  23     QIOChannelSocket *listen_ioc;
  24     int watch;
  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 gboolean nbd_accept(QIOChannel *ioc, GIOCondition condition,
  36                            gpointer opaque)
  37 {
  38     QIOChannelSocket *cioc;
  39
  40     if (!nbd_server) {
  41         return FALSE;
  42     }
  43
  44     cioc = qio_channel_socket_accept(QIO_CHANNEL_SOCKET(ioc),
  45                                      NULL);
  46     if (!cioc) {
  47         return TRUE;
  48     }
  49
  50     qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server");
  51     nbd_client_new(NULL, cioc,
  52                    nbd_server->tlscreds, NULL,
  53                    nbd_blockdev_client_closed);
  54     object_unref(OBJECT(cioc));
  55     return TRUE;
  56 }
  57
  58
  59 static void nbd_server_free(NBDServerData *server)
  60 {
  61     if (!server) {
  62         return;
  63     }
  64
  65     if (server->watch != -1) {
  66         g_source_remove(server->watch);
  67     }
  68     object_unref(OBJECT(server->listen_ioc));
  69     if (server->tlscreds) {
  70         object_unref(OBJECT(server->tlscreds));
  71     }
  72
  73     g_free(server);
  74 }
  75
  76 static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp)
  77 {
  78     Object *obj;
  79     QCryptoTLSCreds *creds;
  80
  81     obj = object_resolve_path_component(
  82         object_get_objects_root(), id);
  83     if (!obj) {
  84         error_setg(errp, "No TLS credentials with id '%s'",
  85                    id);
  86         return NULL;
  87     }
  88     creds = (QCryptoTLSCreds *)
  89         object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS);
  90     if (!creds) {
  91         error_setg(errp, "Object with id '%s' is not TLS credentials",
  92                    id);
  93         return NULL;
  94     }
  95
  96     if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
  97         error_setg(errp,
  98                    "Expecting TLS credentials with a server endpoint");
  99         return NULL;
 100     }
 101     object_ref(obj);
 102     return creds;
 103 }
 104
 105
 106 void qmp_nbd_server_start(SocketAddress *addr,
 107                           bool has_tls_creds, const char *tls_creds,
 108                           Error **errp)
 109 {
 110     if (nbd_server) {
 111         error_setg(errp, "NBD server already running");
 112         return;
 113     }
 114
 115     nbd_server = g_new0(NBDServerData, 1);
 116     nbd_server->watch = -1;
 117     nbd_server->listen_ioc = qio_channel_socket_new();
 118     qio_channel_set_name(QIO_CHANNEL(nbd_server->listen_ioc),
 119                          "nbd-listener");
 120     if (qio_channel_socket_listen_sync(
 121             nbd_server->listen_ioc, addr, errp) < 0) {
 122         goto error;
 123     }
 124
 125     if (has_tls_creds) {
 126         nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp);
 127         if (!nbd_server->tlscreds) {
 128             goto error;
 129         }
 130
 131         /* TODO SOCKET_ADDRESS_KIND_FD where fd has AF_INET or AF_INET6 */
 132         if (addr->type != SOCKET_ADDRESS_KIND_INET) {
 133             error_setg(errp, "TLS is only supported with IPv4/IPv6");
 134             goto error;
 135         }
 136     }
 137
 138     nbd_server->watch = qio_channel_add_watch(
 139         QIO_CHANNEL(nbd_server->listen_ioc),
 140         G_IO_IN,
 141         nbd_accept,
 142         NULL,
 143         NULL);
 144
 145     return;
 146
 147  error:
 148     nbd_server_free(nbd_server);
 149     nbd_server = NULL;
 150 }
 151
 152 void qmp_nbd_server_add(const char *device, bool has_writable, bool writable,
 153                         Error **errp)
 154 {
 155     BlockDriverState *bs = NULL;
 156     BlockBackend *on_eject_blk;
 157     NBDExport *exp;
 158
 159     if (!nbd_server) {
 160         error_setg(errp, "NBD server not running");
 161         return;
 162     }
 163
 164     if (nbd_export_find(device)) {
 165         error_setg(errp, "NBD server already exporting device '%s'", device);
 166         return;
 167     }
 168
 169     on_eject_blk = blk_by_name(device);
 170
 171     bs = bdrv_lookup_bs(device, device, errp);
 172     if (!bs) {
 173         return;
 174     }
 175
 176     if (!has_writable) {
 177         writable = false;
 178     }
 179     if (bdrv_is_read_only(bs)) {
 180         writable = false;
 181     }
 182
 183     exp = nbd_export_new(bs, 0, -1, writable ? 0 : NBD_FLAG_READ_ONLY,
 184                          NULL, false, on_eject_blk, errp);
 185     if (!exp) {
 186         return;
 187     }
 188
 189     nbd_export_set_name(exp, device);
 190
 191     /* The list of named exports has a strong reference to this export now and
 192      * our only way of accessing it is through nbd_export_find(), so we can drop
 193      * the strong reference that is @exp. */
 194     nbd_export_put(exp);
 195 }
 196
 197 void qmp_nbd_server_stop(Error **errp)
 198 {
 199     nbd_export_close_all();
 200
 201     nbd_server_free(nbd_server);
 202     nbd_server = NULL;
 203 }