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 "block/nbd.h"
  19 #include "io/channel-socket.h"
  20 #include "io/net-listener.h"
  21
  22 typedef struct NBDServerData {
  23     QIONetListener *listener;
  24     QCryptoTLSCreds *tlscreds;
  25     char *tlsauthz;
  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, nbd_server->tlsauthz,
  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     g_free(server->tlsauthz);
  56
  57     g_free(server);
  58 }
  59
  60 static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp)
  61 {
  62     Object *obj;
  63     QCryptoTLSCreds *creds;
  64
  65     obj = object_resolve_path_component(
  66         object_get_objects_root(), id);
  67     if (!obj) {
  68         error_setg(errp, "No TLS credentials with id '%s'",
  69                    id);
  70         return NULL;
  71     }
  72     creds = (QCryptoTLSCreds *)
  73         object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS);
  74     if (!creds) {
  75         error_setg(errp, "Object with id '%s' is not TLS credentials",
  76                    id);
  77         return NULL;
  78     }
  79
  80     if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
  81         error_setg(errp,
  82                    "Expecting TLS credentials with a server endpoint");
  83         return NULL;
  84     }
  85     object_ref(obj);
  86     return creds;
  87 }
  88
  89
  90 void nbd_server_start(SocketAddress *addr, const char *tls_creds,
  91                       const char *tls_authz, Error **errp)
  92 {
  93     if (nbd_server) {
  94         error_setg(errp, "NBD server already running");
  95         return;
  96     }
  97
  98     nbd_server = g_new0(NBDServerData, 1);
  99     nbd_server->listener = qio_net_listener_new();
 100
 101     qio_net_listener_set_name(nbd_server->listener,
 102                               "nbd-listener");
 103
 104     if (qio_net_listener_open_sync(nbd_server->listener, addr, 1, errp) < 0) {
 105         goto error;
 106     }
 107
 108     if (tls_creds) {
 109         nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp);
 110         if (!nbd_server->tlscreds) {
 111             goto error;
 112         }
 113
 114         /* TODO SOCKET_ADDRESS_TYPE_FD where fd has AF_INET or AF_INET6 */
 115         if (addr->type != SOCKET_ADDRESS_TYPE_INET) {
 116             error_setg(errp, "TLS is only supported with IPv4/IPv6");
 117             goto error;
 118         }
 119     }
 120
 121     nbd_server->tlsauthz = g_strdup(tls_authz);
 122
 123     qio_net_listener_set_client_func(nbd_server->listener,
 124                                      nbd_accept,
 125                                      NULL,
 126                                      NULL);
 127
 128     return;
 129
 130  error:
 131     nbd_server_free(nbd_server);
 132     nbd_server = NULL;
 133 }
 134
 135 void qmp_nbd_server_start(SocketAddressLegacy *addr,
 136                           bool has_tls_creds, const char *tls_creds,
 137                           bool has_tls_authz, const char *tls_authz,
 138                           Error **errp)
 139 {
 140     SocketAddress *addr_flat = socket_address_flatten(addr);
 141
 142     nbd_server_start(addr_flat, tls_creds, tls_authz, errp);
 143     qapi_free_SocketAddress(addr_flat);
 144 }
 145
 146 void qmp_nbd_server_add(const char *device, bool has_name, const char *name,
 147                         bool has_writable, bool writable,
 148                         bool has_bitmap, const char *bitmap, Error **errp)
 149 {
 150     BlockDriverState *bs = NULL;
 151     BlockBackend *on_eject_blk;
 152     NBDExport *exp;
 153     int64_t len;
 154     AioContext *aio_context;
 155
 156     if (!nbd_server) {
 157         error_setg(errp, "NBD server not running");
 158         return;
 159     }
 160
 161     if (!has_name) {
 162         name = device;
 163     }
 164
 165     if (strlen(name) > NBD_MAX_STRING_SIZE) {
 166         error_setg(errp, "export name '%s' too long", name);
 167         return;
 168     }
 169
 170     if (nbd_export_find(name)) {
 171         error_setg(errp, "NBD server already has export named '%s'", name);
 172         return;
 173     }
 174
 175     on_eject_blk = blk_by_name(device);
 176
 177     bs = bdrv_lookup_bs(device, device, errp);
 178     if (!bs) {
 179         return;
 180     }
 181
 182     aio_context = bdrv_get_aio_context(bs);
 183     aio_context_acquire(aio_context);
 184     len = bdrv_getlength(bs);
 185     if (len < 0) {
 186         error_setg_errno(errp, -len,
 187                          "Failed to determine the NBD export's length");
 188         goto out;
 189     }
 190
 191     if (!has_writable) {
 192         writable = false;
 193     }
 194     if (bdrv_is_read_only(bs)) {
 195         writable = false;
 196     }
 197
 198     exp = nbd_export_new(bs, 0, len, name, NULL, bitmap, !writable, !writable,
 199                          NULL, false, on_eject_blk, errp);
 200     if (!exp) {
 201         goto out;
 202     }
 203
 204     /* The list of named exports has a strong reference to this export now and
 205      * our only way of accessing it is through nbd_export_find(), so we can drop
 206      * the strong reference that is @exp. */
 207     nbd_export_put(exp);
 208
 209  out:
 210     aio_context_release(aio_context);
 211 }
 212
 213 void qmp_nbd_server_remove(const char *name,
 214                            bool has_mode, NbdServerRemoveMode mode,
 215                            Error **errp)
 216 {
 217     NBDExport *exp;
 218     AioContext *aio_context;
 219
 220     if (!nbd_server) {
 221         error_setg(errp, "NBD server not running");
 222         return;
 223     }
 224
 225     exp = nbd_export_find(name);
 226     if (exp == NULL) {
 227         error_setg(errp, "Export '%s' is not found", name);
 228         return;
 229     }
 230
 231     if (!has_mode) {
 232         mode = NBD_SERVER_REMOVE_MODE_SAFE;
 233     }
 234
 235     aio_context = nbd_export_aio_context(exp);
 236     aio_context_acquire(aio_context);
 237     nbd_export_remove(exp, mode, errp);
 238     aio_context_release(aio_context);
 239 }
 240
 241 void qmp_nbd_server_stop(Error **errp)
 242 {
 243     if (!nbd_server) {
 244         error_setg(errp, "NBD server not running");
 245         return;
 246     }
 247
 248     nbd_export_close_all();
 249
 250     nbd_server_free(nbd_server);
 251     nbd_server = NULL;
 252 }