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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 "block/nbd.h"
20 #include "io/channel-socket.h"
21
22 typedef struct NBDServerData {
23 QIOChannelSocket *listen_ioc;
24 int watch;
25 QCryptoTLSCreds *tlscreds;
26 } NBDServerData;
27
28 static NBDServerData *nbd_server;
29
30
31 static gboolean nbd_accept(QIOChannel *ioc, GIOCondition condition,
32 gpointer opaque)
33 {
34 QIOChannelSocket *cioc;
35
36 if (!nbd_server) {
37 return FALSE;
38 }
39
40 cioc = qio_channel_socket_accept(QIO_CHANNEL_SOCKET(ioc),
41 NULL);
42 if (!cioc) {
43 return TRUE;
44 }
45
46 qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server");
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 qio_channel_set_name(QIO_CHANNEL(nbd_server->listen_ioc),
115 "nbd-listener");
116 if (qio_channel_socket_listen_sync(
117 nbd_server->listen_ioc, addr, errp) < 0) {
118 goto error;
119 }
120
121 if (has_tls_creds) {
122 nbd_server->tlscreds = nbd_get_tls_creds(tls_creds, errp);
123 if (!nbd_server->tlscreds) {
124 goto error;
125 }
126
127 if (addr->type != SOCKET_ADDRESS_KIND_INET) {
128 error_setg(errp, "TLS is only supported with IPv4/IPv6");
129 goto error;
130 }
131 }
132
133 nbd_server->watch = qio_channel_add_watch(
134 QIO_CHANNEL(nbd_server->listen_ioc),
135 G_IO_IN,
136 nbd_accept,
137 NULL,
138 NULL);
139
140 return;
141
142 error:
143 nbd_server_free(nbd_server);
144 nbd_server = NULL;
145 }
146
147 void qmp_nbd_server_add(const char *device, bool has_writable, bool writable,
148 Error **errp)
149 {
150 BlockDriverState *bs = NULL;
151 BlockBackend *on_eject_blk;
152 NBDExport *exp;
153
154 if (!nbd_server) {
155 error_setg(errp, "NBD server not running");
156 return;
157 }
158
159 if (nbd_export_find(device)) {
160 error_setg(errp, "NBD server already exporting device '%s'", device);
161 return;
162 }
163
164 on_eject_blk = blk_by_name(device);
165
166 bs = bdrv_lookup_bs(device, device, errp);
167 if (!bs) {
168 return;
169 }
170
171 if (!has_writable) {
172 writable = false;
173 }
174 if (bdrv_is_read_only(bs)) {
175 writable = false;
176 }
177
178 exp = nbd_export_new(bs, 0, -1, writable ? 0 : NBD_FLAG_READ_ONLY,
179 NULL, false, on_eject_blk, errp);
180 if (!exp) {
181 return;
182 }
183
184 nbd_export_set_name(exp, device);
185
186 /* The list of named exports has a strong reference to this export now and
187 * our only way of accessing it is through nbd_export_find(), so we can drop
188 * the strong reference that is @exp. */
189 nbd_export_put(exp);
190 }
191
192 void qmp_nbd_server_stop(Error **errp)
193 {
194 nbd_export_close_all();
195
196 nbd_server_free(nbd_server);
197 nbd_server = NULL;
198 }