LXR qemu/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 "trace.h"
  20#include "block/nbd.h"
  21#include "io/channel-socket.h"
  22
  23typedef struct NBDServerData {
  24    QIOChannelSocket *listen_ioc;
  25    int watch;
  26    QCryptoTLSCreds *tlscreds;
  27} NBDServerData;
  28
  29static NBDServerData *nbd_server;
  30
  31
  32static gboolean nbd_accept(QIOChannel *ioc, GIOCondition condition,
  33                           gpointer opaque)
  34{
  35    QIOChannelSocket *cioc;
  36
  37    if (!nbd_server) {
  38        return FALSE;
  39    }
  40
  41    cioc = qio_channel_socket_accept(QIO_CHANNEL_SOCKET(ioc),
  42                                     NULL);
  43    if (!cioc) {
  44        return TRUE;
  45    }
  46
  47    qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server");
  48    nbd_client_new(NULL, cioc,
  49                   nbd_server->tlscreds, NULL,
  50                   nbd_client_put);
  51    object_unref(OBJECT(cioc));
  52    return TRUE;
  53}
  54
  55
  56static void nbd_server_free(NBDServerData *server)
  57{
  58    if (!server) {
  59        return;
  60    }
  61
  62    if (server->watch != -1) {
  63        g_source_remove(server->watch);
  64    }
  65    object_unref(OBJECT(server->listen_ioc));
  66    if (server->tlscreds) {
  67        object_unref(OBJECT(server->tlscreds));
  68    }
  69
  70    g_free(server);
  71}
  72
  73static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp)
  74{
  75    Object *obj;
  76    QCryptoTLSCreds *creds;
  77
  78    obj = object_resolve_path_component(
  79        object_get_objects_root(), id);
  80    if (!obj) {
  81        error_setg(errp, "No TLS credentials with id '%s'",
  82                   id);
  83        return NULL;
  84    }
  85    creds = (QCryptoTLSCreds *)
  86        object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS);
  87    if (!creds) {
  88        error_setg(errp, "Object with id '%s' is not TLS credentials",
  89                   id);
  90        return NULL;
  91    }
  92
  93    if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
  94        error_setg(errp,
  95                   "Expecting TLS credentials with a server endpoint");
  96        return NULL;
  97    }
  98    object_ref(obj);
  99    return creds;
 100}
 101
 102
 103void qmp_nbd_server_start(SocketAddress *addr,
 104                          bool has_tls_creds, const char *tls_creds,
 105                          Error **errp)
 106{
 107    if (nbd_server) {
 108        error_setg(errp, "NBD server already running");
 109        return;
 110    }
 111
 112    nbd_server = g_new0(NBDServerData, 1);
 113    nbd_server->watch = -1;
 114    nbd_server->listen_ioc = qio_channel_socket_new();
 115    qio_channel_set_name(QIO_CHANNEL(nbd_server->listen_ioc),
 116                         "nbd-listener");
 117    if (qio_channel_socket_listen_sync(
 118            nbd_server->listen_ioc, addr, errp) < 0) {
 119        goto error;
 120    }
 121
 122    if (has_tls_creds) {
 123        nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp);
 124        if (!nbd_server->tlscreds) {
 125            goto error;
 126        }
 127
 128        if (addr->type != SOCKET_ADDRESS_KIND_INET) {
 129            error_setg(errp, "TLS is only supported with IPv4/IPv6");
 130            goto error;
 131        }
 132    }
 133
 134    nbd_server->watch = qio_channel_add_watch(
 135        QIO_CHANNEL(nbd_server->listen_ioc),
 136        G_IO_IN,
 137        nbd_accept,
 138        NULL,
 139        NULL);
 140
 141    return;
 142
 143 error:
 144    nbd_server_free(nbd_server);
 145    nbd_server = NULL;
 146}
 147
 148void qmp_nbd_server_add(const char *device, bool has_writable, bool writable,
 149                        Error **errp)
 150{
 151    BlockDriverState *bs = NULL;
 152    BlockBackend *on_eject_blk;
 153    NBDExport *exp;
 154
 155    if (!nbd_server) {
 156        error_setg(errp, "NBD server not running");
 157        return;
 158    }
 159
 160    if (nbd_export_find(device)) {
 161        error_setg(errp, "NBD server already exporting device '%s'", device);
 162        return;
 163    }
 164
 165    on_eject_blk = blk_by_name(device);
 166
 167    bs = bdrv_lookup_bs(device, device, errp);
 168    if (!bs) {
 169        return;
 170    }
 171
 172    if (!has_writable) {
 173        writable = false;
 174    }
 175    if (bdrv_is_read_only(bs)) {
 176        writable = false;
 177    }
 178
 179    exp = nbd_export_new(bs, 0, -1, writable ? 0 : NBD_FLAG_READ_ONLY,
 180                         NULL, false, on_eject_blk, errp);
 181    if (!exp) {
 182        return;
 183    }
 184
 185    nbd_export_set_name(exp, device);
 186
 187    /* The list of named exports has a strong reference to this export now and
 188     * our only way of accessing it is through nbd_export_find(), so we can drop
 189     * the strong reference that is @exp. */
 190    nbd_export_put(exp);
 191}
 192
 193void qmp_nbd_server_stop(Error **errp)
 194{
 195    nbd_export_close_all();
 196
 197    nbd_server_free(nbd_server);
 198    nbd_server = NULL;
 199}
 200