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    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
  55static 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
  72static 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
 102void 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    if (qio_channel_socket_listen_sync(
 115            nbd_server->listen_ioc, addr, errp) < 0) {
 116        goto error;
 117    }
 118
 119    if (has_tls_creds) {
 120        nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp);
 121        if (!nbd_server->tlscreds) {
 122            goto error;
 123        }
 124
 125        if (addr->type != SOCKET_ADDRESS_KIND_INET) {
 126            error_setg(errp, "TLS is only supported with IPv4/IPv6");
 127            goto error;
 128        }
 129    }
 130
 131    nbd_server->watch = qio_channel_add_watch(
 132        QIO_CHANNEL(nbd_server->listen_ioc),
 133        G_IO_IN,
 134        nbd_accept,
 135        NULL,
 136        NULL);
 137
 138    return;
 139
 140 error:
 141    nbd_server_free(nbd_server);
 142    nbd_server = NULL;
 143}
 144
 145void qmp_nbd_server_add(const char *device, bool has_writable, bool writable,
 146                        Error **errp)
 147{
 148    BlockBackend *blk;
 149    NBDExport *exp;
 150
 151    if (!nbd_server) {
 152        error_setg(errp, "NBD server not running");
 153        return;
 154    }
 155
 156    if (nbd_export_find(device)) {
 157        error_setg(errp, "NBD server already exporting device '%s'", device);
 158        return;
 159    }
 160
 161    blk = blk_by_name(device);
 162    if (!blk) {
 163        error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
 164                  "Device '%s' not found", device);
 165        return;
 166    }
 167    if (!blk_is_inserted(blk)) {
 168        error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, device);
 169        return;
 170    }
 171
 172    if (!has_writable) {
 173        writable = false;
 174    }
 175    if (blk_is_read_only(blk)) {
 176        writable = false;
 177    }
 178
 179    exp = nbd_export_new(blk, 0, -1, writable ? 0 : NBD_FLAG_READ_ONLY, NULL,
 180                         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