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     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
  56 static 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
  73 static 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
 103 void 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
 148 void 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
 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 }