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
  31 static gboolean nbd_accept(QIOChannel *ioc, GIOCondition condition,
  32                            gpointer opaque)
  33 {
  34     QIOChannelSocket *cioc;
  35
  36     if (!nbd_server) {
  37         return FALSE;
  38     }
  39
  40     cioc = qio_channel_socket_accept(QIO_CHANNEL_SOCKET(ioc),
  41                                      NULL);
  42     if (!cioc) {
  43         return TRUE;
  44     }
  45
  46     qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server");
  47     nbd_client_new(NULL, cioc,
  48                    nbd_server->tlscreds, NULL,
  49                    nbd_client_put);
  50     object_unref(OBJECT(cioc));
  51     return TRUE;
  52 }
  53
  54
  55 static void nbd_server_free(NBDServerData *server)
  56 {
  57     if (!server) {
  58         return;
  59     }
  60
  61     if (server->watch != -1) {
  62         g_source_remove(server->watch);
  63     }
  64     object_unref(OBJECT(server->listen_ioc));
  65     if (server->tlscreds) {
  66         object_unref(OBJECT(server->tlscreds));
  67     }
  68
  69     g_free(server);
  70 }
  71
  72 static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp)
  73 {
  74     Object *obj;
  75     QCryptoTLSCreds *creds;
  76
  77     obj = object_resolve_path_component(
  78         object_get_objects_root(), id);
  79     if (!obj) {
  80         error_setg(errp, "No TLS credentials with id '%s'",
  81                    id);
  82         return NULL;
  83     }
  84     creds = (QCryptoTLSCreds *)
  85         object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS);
  86     if (!creds) {
  87         error_setg(errp, "Object with id '%s' is not TLS credentials",
  88                    id);
  89         return NULL;
  90     }
  91
  92     if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
  93         error_setg(errp,
  94                    "Expecting TLS credentials with a server endpoint");
  95         return NULL;
  96     }
  97     object_ref(obj);
  98     return creds;
  99 }
 100
 101
 102 void qmp_nbd_server_start(SocketAddress *addr,
 103                           bool has_tls_creds, const char *tls_creds,
 104                           Error **errp)
 105 {
 106     if (nbd_server) {
 107         error_setg(errp, "NBD server already running");
 108         return;
 109     }
 110
 111     nbd_server = g_new0(NBDServerData, 1);
 112     nbd_server->watch = -1;
 113     nbd_server->listen_ioc = qio_channel_socket_new();
 114     qio_channel_set_name(QIO_CHANNEL(nbd_server->listen_ioc),
 115                          "nbd-listener");
 116     if (qio_channel_socket_listen_sync(
 117             nbd_server->listen_ioc, addr, errp) < 0) {
 118         goto error;
 119     }
 120
 121     if (has_tls_creds) {
 122         nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp);
 123         if (!nbd_server->tlscreds) {
 124             goto error;
 125         }
 126
 127         if (addr->type != SOCKET_ADDRESS_KIND_INET) {
 128             error_setg(errp, "TLS is only supported with IPv4/IPv6");
 129             goto error;
 130         }
 131     }
 132
 133     nbd_server->watch = qio_channel_add_watch(
 134         QIO_CHANNEL(nbd_server->listen_ioc),
 135         G_IO_IN,
 136         nbd_accept,
 137         NULL,
 138         NULL);
 139
 140     return;
 141
 142  error:
 143     nbd_server_free(nbd_server);
 144     nbd_server = NULL;
 145 }
 146
 147 void qmp_nbd_server_add(const char *device, bool has_writable, bool writable,
 148                         Error **errp)
 149 {
 150     BlockDriverState *bs = NULL;
 151     BlockBackend *on_eject_blk;
 152     NBDExport *exp;
 153
 154     if (!nbd_server) {
 155         error_setg(errp, "NBD server not running");
 156         return;
 157     }
 158
 159     if (nbd_export_find(device)) {
 160         error_setg(errp, "NBD server already exporting device '%s'", device);
 161         return;
 162     }
 163
 164     on_eject_blk = blk_by_name(device);
 165
 166     bs = bdrv_lookup_bs(device, device, errp);
 167     if (!bs) {
 168         return;
 169     }
 170
 171     if (!has_writable) {
 172         writable = false;
 173     }
 174     if (bdrv_is_read_only(bs)) {
 175         writable = false;
 176     }
 177
 178     exp = nbd_export_new(bs, 0, -1, writable ? 0 : NBD_FLAG_READ_ONLY,
 179                          NULL, false, on_eject_blk, errp);
 180     if (!exp) {
 181         return;
 182     }
 183
 184     nbd_export_set_name(exp, device);
 185
 186     /* The list of named exports has a strong reference to this export now and
 187      * our only way of accessing it is through nbd_export_find(), so we can drop
 188      * the strong reference that is @exp. */
 189     nbd_export_put(exp);
 190 }
 191
 192 void qmp_nbd_server_stop(Error **errp)
 193 {
 194     nbd_export_close_all();
 195
 196     nbd_server_free(nbd_server);
 197     nbd_server = NULL;
 198 }