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/qapi-commands-block.h"
  18 #include "sysemu/sysemu.h"
  19 #include "block/nbd.h"
  20 #include "io/channel-socket.h"
  21 #include "io/net-listener.h"
  22
  23 typedef struct NBDServerData {
  24     QIONetListener *listener;
  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 void nbd_accept(QIONetListener *listener, QIOChannelSocket *cioc,
  36                        gpointer opaque)
  37 {
  38     qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server");
  39     nbd_client_new(cioc, nbd_server->tlscreds, NULL,
  40                    nbd_blockdev_client_closed);
  41 }
  42
  43
  44 static void nbd_server_free(NBDServerData *server)
  45 {
  46     if (!server) {
  47         return;
  48     }
  49
  50     qio_net_listener_disconnect(server->listener);
  51     object_unref(OBJECT(server->listener));
  52     if (server->tlscreds) {
  53         object_unref(OBJECT(server->tlscreds));
  54     }
  55
  56     g_free(server);
  57 }
  58
  59 static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp)
  60 {
  61     Object *obj;
  62     QCryptoTLSCreds *creds;
  63
  64     obj = object_resolve_path_component(
  65         object_get_objects_root(), id);
  66     if (!obj) {
  67         error_setg(errp, "No TLS credentials with id '%s'",
  68                    id);
  69         return NULL;
  70     }
  71     creds = (QCryptoTLSCreds *)
  72         object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS);
  73     if (!creds) {
  74         error_setg(errp, "Object with id '%s' is not TLS credentials",
  75                    id);
  76         return NULL;
  77     }
  78
  79     if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
  80         error_setg(errp,
  81                    "Expecting TLS credentials with a server endpoint");
  82         return NULL;
  83     }
  84     object_ref(obj);
  85     return creds;
  86 }
  87
  88
  89 void nbd_server_start(SocketAddress *addr, const char *tls_creds,
  90                       Error **errp)
  91 {
  92     if (nbd_server) {
  93         error_setg(errp, "NBD server already running");
  94         return;
  95     }
  96
  97     nbd_server = g_new0(NBDServerData, 1);
  98     nbd_server->listener = qio_net_listener_new();
  99
 100     qio_net_listener_set_name(nbd_server->listener,
 101                               "nbd-listener");
 102
 103     if (qio_net_listener_open_sync(nbd_server->listener, addr, errp) < 0) {
 104         goto error;
 105     }
 106
 107     if (tls_creds) {
 108         nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp);
 109         if (!nbd_server->tlscreds) {
 110             goto error;
 111         }
 112
 113         /* TODO SOCKET_ADDRESS_TYPE_FD where fd has AF_INET or AF_INET6 */
 114         if (addr->type != SOCKET_ADDRESS_TYPE_INET) {
 115             error_setg(errp, "TLS is only supported with IPv4/IPv6");
 116             goto error;
 117         }
 118     }
 119
 120     qio_net_listener_set_client_func(nbd_server->listener,
 121                                      nbd_accept,
 122                                      NULL,
 123                                      NULL);
 124
 125     return;
 126
 127  error:
 128     nbd_server_free(nbd_server);
 129     nbd_server = NULL;
 130 }
 131
 132 void qmp_nbd_server_start(SocketAddressLegacy *addr,
 133                           bool has_tls_creds, const char *tls_creds,
 134                           Error **errp)
 135 {
 136     SocketAddress *addr_flat = socket_address_flatten(addr);
 137
 138     nbd_server_start(addr_flat, tls_creds, errp);
 139     qapi_free_SocketAddress(addr_flat);
 140 }
 141
 142 void qmp_nbd_server_add(const char *device, bool has_name, const char *name,
 143                         bool has_writable, bool writable,
 144                         bool has_bitmap, const char *bitmap, Error **errp)
 145 {
 146     BlockDriverState *bs = NULL;
 147     BlockBackend *on_eject_blk;
 148     NBDExport *exp;
 149     int64_t len;
 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     len = bdrv_getlength(bs);
 173     if (len < 0) {
 174         error_setg_errno(errp, -len,
 175                          "Failed to determine the NBD export's length");
 176         return;
 177     }
 178
 179     if (!has_writable) {
 180         writable = false;
 181     }
 182     if (bdrv_is_read_only(bs)) {
 183         writable = false;
 184     }
 185
 186     exp = nbd_export_new(bs, 0, len, name, NULL, bitmap,
 187                          writable ? 0 : NBD_FLAG_READ_ONLY,
 188                          NULL, false, on_eject_blk, errp);
 189     if (!exp) {
 190         return;
 191     }
 192
 193     /* The list of named exports has a strong reference to this export now and
 194      * our only way of accessing it is through nbd_export_find(), so we can drop
 195      * the strong reference that is @exp. */
 196     nbd_export_put(exp);
 197 }
 198
 199 void qmp_nbd_server_remove(const char *name,
 200                            bool has_mode, NbdServerRemoveMode mode,
 201                            Error **errp)
 202 {
 203     NBDExport *exp;
 204
 205     if (!nbd_server) {
 206         error_setg(errp, "NBD server not running");
 207         return;
 208     }
 209
 210     exp = nbd_export_find(name);
 211     if (exp == NULL) {
 212         error_setg(errp, "Export '%s' is not found", name);
 213         return;
 214     }
 215
 216     if (!has_mode) {
 217         mode = NBD_SERVER_REMOVE_MODE_SAFE;
 218     }
 219
 220     nbd_export_remove(exp, mode, errp);
 221 }
 222
 223 void qmp_nbd_server_stop(Error **errp)
 224 {
 225     if (!nbd_server) {
 226         error_setg(errp, "NBD server not running");
 227         return;
 228     }
 229
 230     nbd_export_close_all();
 231
 232     nbd_server_free(nbd_server);
 233     nbd_server = NULL;
 234 }