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/clone-visitor.h"
18 #include "qapi/qapi-visit-block-export.h"
19 #include "qapi/qapi-commands-block-export.h"
20 #include "block/nbd.h"
21 #include "io/channel-socket.h"
22 #include "io/net-listener.h"
23
24 typedef struct NBDConn {
25 QIOChannelSocket *cioc;
26 QLIST_ENTRY(NBDConn) next;
27 } NBDConn;
28
29 typedef struct NBDServerData {
30 QIONetListener *listener;
31 QCryptoTLSCreds *tlscreds;
32 char *tlsauthz;
33 uint32_t max_connections;
34 uint32_t connections;
35 QLIST_HEAD(, NBDConn) conns;
36 } NBDServerData;
37
38 static NBDServerData *nbd_server;
39 static int qemu_nbd_connections = -1; /* Non-negative if this is qemu-nbd */
40
41 static void nbd_update_server_watch(NBDServerData *s);
42
nbd_server_is_qemu_nbd(int max_connections)43 void nbd_server_is_qemu_nbd(int max_connections)
44 {
45 qemu_nbd_connections = max_connections;
46 }
47
nbd_server_is_running(void)48 bool nbd_server_is_running(void)
49 {
50 return nbd_server || qemu_nbd_connections >= 0;
51 }
52
nbd_server_max_connections(void)53 int nbd_server_max_connections(void)
54 {
55 return nbd_server ? nbd_server->max_connections : qemu_nbd_connections;
56 }
57
nbd_blockdev_client_closed(NBDClient * client,bool ignored)58 static void nbd_blockdev_client_closed(NBDClient *client, bool ignored)
59 {
60 NBDConn *conn = nbd_client_owner(client);
61
62 assert(qemu_in_main_thread() && nbd_server);
63
64 object_unref(OBJECT(conn->cioc));
65 QLIST_REMOVE(conn, next);
66 g_free(conn);
67
68 nbd_client_put(client);
69 assert(nbd_server->connections > 0);
70 nbd_server->connections--;
71 nbd_update_server_watch(nbd_server);
72 }
73
nbd_accept(QIONetListener * listener,QIOChannelSocket * cioc,gpointer opaque)74 static void nbd_accept(QIONetListener *listener, QIOChannelSocket *cioc,
75 gpointer opaque)
76 {
77 NBDConn *conn = g_new0(NBDConn, 1);
78
79 assert(qemu_in_main_thread() && nbd_server);
80 nbd_server->connections++;
81 object_ref(OBJECT(cioc));
82 conn->cioc = cioc;
83 QLIST_INSERT_HEAD(&nbd_server->conns, conn, next);
84 nbd_update_server_watch(nbd_server);
85
86 qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server");
87 /* TODO - expose handshake timeout as QMP option */
88 nbd_client_new(cioc, NBD_DEFAULT_HANDSHAKE_MAX_SECS,
89 nbd_server->tlscreds, nbd_server->tlsauthz,
90 nbd_blockdev_client_closed, conn);
91 }
92
nbd_update_server_watch(NBDServerData * s)93 static void nbd_update_server_watch(NBDServerData *s)
94 {
95 if (s->listener) {
96 if (!s->max_connections || s->connections < s->max_connections) {
97 qio_net_listener_set_client_func(s->listener, nbd_accept, NULL,
98 NULL);
99 } else {
100 qio_net_listener_set_client_func(s->listener, NULL, NULL, NULL);
101 }
102 }
103 }
104
nbd_server_free(NBDServerData * server)105 static void nbd_server_free(NBDServerData *server)
106 {
107 NBDConn *conn, *tmp;
108
109 if (!server) {
110 return;
111 }
112
113 /*
114 * Forcefully close the listener socket, and any clients that have
115 * not yet disconnected on their own.
116 */
117 qio_net_listener_disconnect(server->listener);
118 object_unref(OBJECT(server->listener));
119 server->listener = NULL;
120 QLIST_FOREACH_SAFE(conn, &server->conns, next, tmp) {
121 qio_channel_shutdown(QIO_CHANNEL(conn->cioc), QIO_CHANNEL_SHUTDOWN_BOTH,
122 NULL);
123 }
124
125 AIO_WAIT_WHILE_UNLOCKED(NULL, server->connections > 0);
126
127 if (server->tlscreds) {
128 object_unref(OBJECT(server->tlscreds));
129 }
130 g_free(server->tlsauthz);
131
132 g_free(server);
133 }
134
nbd_get_tls_creds(const char * id,Error ** errp)135 static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp)
136 {
137 Object *obj;
138 QCryptoTLSCreds *creds;
139
140 obj = object_resolve_path_component(
141 object_get_objects_root(), id);
142 if (!obj) {
143 error_setg(errp, "No TLS credentials with id '%s'",
144 id);
145 return NULL;
146 }
147 creds = (QCryptoTLSCreds *)
148 object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS);
149 if (!creds) {
150 error_setg(errp, "Object with id '%s' is not TLS credentials",
151 id);
152 return NULL;
153 }
154
155 if (!qcrypto_tls_creds_check_endpoint(creds,
156 QCRYPTO_TLS_CREDS_ENDPOINT_SERVER,
157 errp)) {
158 return NULL;
159 }
160 object_ref(obj);
161 return creds;
162 }
163
164
nbd_server_start(SocketAddress * addr,const char * tls_creds,const char * tls_authz,uint32_t max_connections,Error ** errp)165 void nbd_server_start(SocketAddress *addr, const char *tls_creds,
166 const char *tls_authz, uint32_t max_connections,
167 Error **errp)
168 {
169 if (nbd_server) {
170 error_setg(errp, "NBD server already running");
171 return;
172 }
173
174 nbd_server = g_new0(NBDServerData, 1);
175 nbd_server->max_connections = max_connections;
176 nbd_server->listener = qio_net_listener_new();
177
178 qio_net_listener_set_name(nbd_server->listener,
179 "nbd-listener");
180
181 /*
182 * Because this server is persistent, a backlog of SOMAXCONN is
183 * better than trying to size it to max_connections.
184 */
185 if (qio_net_listener_open_sync(nbd_server->listener, addr, SOMAXCONN,
186 errp) < 0) {
187 goto error;
188 }
189
190 if (tls_creds) {
191 nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp);
192 if (!nbd_server->tlscreds) {
193 goto error;
194 }
195 }
196
197 nbd_server->tlsauthz = g_strdup(tls_authz);
198
199 nbd_update_server_watch(nbd_server);
200
201 return;
202
203 error:
204 nbd_server_free(nbd_server);
205 nbd_server = NULL;
206 }
207
nbd_server_start_options(NbdServerOptions * arg,Error ** errp)208 void nbd_server_start_options(NbdServerOptions *arg, Error **errp)
209 {
210 if (!arg->has_max_connections) {
211 arg->max_connections = NBD_DEFAULT_MAX_CONNECTIONS;
212 }
213
214 nbd_server_start(arg->addr, arg->tls_creds, arg->tls_authz,
215 arg->max_connections, errp);
216 }
217
qmp_nbd_server_start(SocketAddressLegacy * addr,const char * tls_creds,const char * tls_authz,bool has_max_connections,uint32_t max_connections,Error ** errp)218 void qmp_nbd_server_start(SocketAddressLegacy *addr,
219 const char *tls_creds,
220 const char *tls_authz,
221 bool has_max_connections, uint32_t max_connections,
222 Error **errp)
223 {
224 SocketAddress *addr_flat = socket_address_flatten(addr);
225
226 if (!has_max_connections) {
227 max_connections = NBD_DEFAULT_MAX_CONNECTIONS;
228 }
229
230 nbd_server_start(addr_flat, tls_creds, tls_authz, max_connections, errp);
231 qapi_free_SocketAddress(addr_flat);
232 }
233
qmp_nbd_server_add(NbdServerAddOptions * arg,Error ** errp)234 void qmp_nbd_server_add(NbdServerAddOptions *arg, Error **errp)
235 {
236 BlockExport *export;
237 BlockDriverState *bs;
238 BlockBackend *on_eject_blk;
239 BlockExportOptions *export_opts;
240
241 bs = bdrv_lookup_bs(arg->device, arg->device, errp);
242 if (!bs) {
243 return;
244 }
245
246 /*
247 * block-export-add would default to the node-name, but we may have to use
248 * the device name as a default here for compatibility.
249 */
250 if (!arg->name) {
251 arg->name = g_strdup(arg->device);
252 }
253
254 export_opts = g_new(BlockExportOptions, 1);
255 *export_opts = (BlockExportOptions) {
256 .type = BLOCK_EXPORT_TYPE_NBD,
257 .id = g_strdup(arg->name),
258 .node_name = g_strdup(bdrv_get_node_name(bs)),
259 .has_writable = arg->has_writable,
260 .writable = arg->writable,
261 };
262 QAPI_CLONE_MEMBERS(BlockExportOptionsNbdBase, &export_opts->u.nbd,
263 qapi_NbdServerAddOptions_base(arg));
264 if (arg->bitmap) {
265 BlockDirtyBitmapOrStr *el = g_new(BlockDirtyBitmapOrStr, 1);
266
267 *el = (BlockDirtyBitmapOrStr) {
268 .type = QTYPE_QSTRING,
269 .u.local = g_strdup(arg->bitmap),
270 };
271 export_opts->u.nbd.has_bitmaps = true;
272 QAPI_LIST_PREPEND(export_opts->u.nbd.bitmaps, el);
273 }
274
275 /*
276 * nbd-server-add doesn't complain when a read-only device should be
277 * exported as writable, but simply downgrades it. This is an error with
278 * block-export-add.
279 */
280 if (bdrv_is_read_only(bs)) {
281 export_opts->has_writable = true;
282 export_opts->writable = false;
283 }
284
285 export = blk_exp_add(export_opts, errp);
286 if (!export) {
287 goto fail;
288 }
289
290 /*
291 * nbd-server-add removes the export when the named BlockBackend used for
292 * @device goes away.
293 */
294 on_eject_blk = blk_by_name(arg->device);
295 if (on_eject_blk) {
296 nbd_export_set_on_eject_blk(export, on_eject_blk);
297 }
298
299 fail:
300 qapi_free_BlockExportOptions(export_opts);
301 }
302
qmp_nbd_server_remove(const char * name,bool has_mode,BlockExportRemoveMode mode,Error ** errp)303 void qmp_nbd_server_remove(const char *name,
304 bool has_mode, BlockExportRemoveMode mode,
305 Error **errp)
306 {
307 BlockExport *exp;
308
309 exp = blk_exp_find(name);
310 if (exp && exp->drv->type != BLOCK_EXPORT_TYPE_NBD) {
311 error_setg(errp, "Block export '%s' is not an NBD export", name);
312 return;
313 }
314
315 qmp_block_export_del(name, has_mode, mode, errp);
316 }
317
qmp_nbd_server_stop(Error ** errp)318 void qmp_nbd_server_stop(Error **errp)
319 {
320 if (!nbd_server) {
321 error_setg(errp, "NBD server not running");
322 return;
323 }
324
325 blk_exp_close_all_type(BLOCK_EXPORT_TYPE_NBD);
326
327 nbd_server_free(nbd_server);
328 nbd_server = NULL;
329 }
330