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
  23 typedef struct NBDServerData {
  24     QIOChannelSocket *listen_ioc;
  25     int watch;
  26     QCryptoTLSCreds *tlscreds;
  27 } NBDServerData;
  28
  29 static NBDServerData *nbd_server;
  30
  31
  32 static 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
  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     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
 145 void 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
 193 void qmp_nbd_server_stop(Error **errp)
 194 {
 195     nbd_export_close_all();
 196
 197     nbd_server_free(nbd_server);
 198     nbd_server = NULL;
 199 }