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/error.h"
  17 #include "qapi/qmp/qerror.h"
  18 #include "sysemu/sysemu.h"
  19 #include "qmp-commands.h"
  20 #include "block/nbd.h"
  21 #include "io/channel-socket.h"
  22 #include "io/net-listener.h"
  23
  24 typedef struct NBDServerData {
  25     QIONetListener *listener;
  26     QCryptoTLSCreds *tlscreds;
  27 } NBDServerData;
  28
  29 static NBDServerData *nbd_server;
  30
  31 static void nbd_blockdev_client_closed(NBDClient *client, bool ignored)
  32 {
  33     nbd_client_put(client);
  34 }
  35
  36 static void nbd_accept(QIONetListener *listener, QIOChannelSocket *cioc,
  37                        gpointer opaque)
  38 {
  39     qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server");
  40     nbd_client_new(NULL, cioc,
  41                    nbd_server->tlscreds, NULL,
  42                    nbd_blockdev_client_closed);
  43 }
  44
  45
  46 static void nbd_server_free(NBDServerData *server)
  47 {
  48     if (!server) {
  49         return;
  50     }
  51
  52     qio_net_listener_disconnect(server->listener);
  53     object_unref(OBJECT(server->listener));
  54     if (server->tlscreds) {
  55         object_unref(OBJECT(server->tlscreds));
  56     }
  57
  58     g_free(server);
  59 }
  60
  61 static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp)
  62 {
  63     Object *obj;
  64     QCryptoTLSCreds *creds;
  65
  66     obj = object_resolve_path_component(
  67         object_get_objects_root(), id);
  68     if (!obj) {
  69         error_setg(errp, "No TLS credentials with id '%s'",
  70                    id);
  71         return NULL;
  72     }
  73     creds = (QCryptoTLSCreds *)
  74         object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS);
  75     if (!creds) {
  76         error_setg(errp, "Object with id '%s' is not TLS credentials",
  77                    id);
  78         return NULL;
  79     }
  80
  81     if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
  82         error_setg(errp,
  83                    "Expecting TLS credentials with a server endpoint");
  84         return NULL;
  85     }
  86     object_ref(obj);
  87     return creds;
  88 }
  89
  90
  91 void nbd_server_start(SocketAddress *addr, const char *tls_creds,
  92                       Error **errp)
  93 {
  94     if (nbd_server) {
  95         error_setg(errp, "NBD server already running");
  96         return;
  97     }
  98
  99     nbd_server = g_new0(NBDServerData, 1);
 100     nbd_server->listener = qio_net_listener_new();
 101
 102     qio_net_listener_set_name(nbd_server->listener,
 103                               "nbd-listener");
 104
 105     if (qio_net_listener_open_sync(nbd_server->listener, addr, errp) < 0) {
 106         goto error;
 107     }
 108
 109     if (tls_creds) {
 110         nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp);
 111         if (!nbd_server->tlscreds) {
 112             goto error;
 113         }
 114
 115         /* TODO SOCKET_ADDRESS_TYPE_FD where fd has AF_INET or AF_INET6 */
 116         if (addr->type != SOCKET_ADDRESS_TYPE_INET) {
 117             error_setg(errp, "TLS is only supported with IPv4/IPv6");
 118             goto error;
 119         }
 120     }
 121
 122     qio_net_listener_set_client_func(nbd_server->listener,
 123                                      nbd_accept,
 124                                      NULL,
 125                                      NULL);
 126
 127     return;
 128
 129  error:
 130     nbd_server_free(nbd_server);
 131     nbd_server = NULL;
 132 }
 133
 134 void qmp_nbd_server_start(SocketAddressLegacy *addr,
 135                           bool has_tls_creds, const char *tls_creds,
 136                           Error **errp)
 137 {
 138     SocketAddress *addr_flat = socket_address_flatten(addr);
 139
 140     nbd_server_start(addr_flat, tls_creds, errp);
 141     qapi_free_SocketAddress(addr_flat);
 142 }
 143
 144 void qmp_nbd_server_add(const char *device, bool has_name, const char *name,
 145                         bool has_writable, bool writable, Error **errp)
 146 {
 147     BlockDriverState *bs = NULL;
 148     BlockBackend *on_eject_blk;
 149     NBDExport *exp;
 150
 151     if (!nbd_server) {
 152         error_setg(errp, "NBD server not running");
 153         return;
 154     }
 155
 156     if (!has_name) {
 157         name = device;
 158     }
 159
 160     if (nbd_export_find(name)) {
 161         error_setg(errp, "NBD server already has export named '%s'", name);
 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, name);
 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
 193 void qmp_nbd_server_remove(const char *name,
 194                            bool has_mode, NbdServerRemoveMode mode,
 195                            Error **errp)
 196 {
 197     NBDExport *exp;
 198
 199     if (!nbd_server) {
 200         error_setg(errp, "NBD server not running");
 201         return;
 202     }
 203
 204     exp = nbd_export_find(name);
 205     if (exp == NULL) {
 206         error_setg(errp, "Export '%s' is not found", name);
 207         return;
 208     }
 209
 210     if (!has_mode) {
 211         mode = NBD_SERVER_REMOVE_MODE_SAFE;
 212     }
 213
 214     nbd_export_remove(exp, mode, errp);
 215 }
 216
 217 void qmp_nbd_server_stop(Error **errp)
 218 {
 219     nbd_export_close_all();
 220
 221     nbd_server_free(nbd_server);
 222     nbd_server = NULL;
 223 }