crypto: introduce new module for TLS anonymous credentials

Introduce a QCryptoTLSCredsAnon class which is used to
manage anonymous TLS credentials. Use of this class is
generally discouraged since it does not offer strong
security, but it is required for backwards compatibility
with the current VNC server implementation.

Simple example CLI configuration:

 $QEMU -object tls-creds-anon,id=tls0,endpoint=server

Example using pre-created diffie-hellman parameters

 $QEMU -object tls-creds-anon,id=tls0,endpoint=server,\
               dir=/path/to/creds/dir

The 'id' value in the -object args will be used to associate the
credentials with the network services. For example, when the VNC
server is later converted it would use

 $QEMU -object tls-creds-anon,id=tls0,.... \
       -vnc 127.0.0.1:1,tls-creds=tls0

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

2 files changed, 224 insertions, 0 deletions

diff --git a/crypto/Makefile.objs b/crypto/Makefile.objs
index aef8dbb79d..283a68b62e 100644
--- a/crypto/Makefile.objs
+++ b/crypto/Makefile.objs
@@ -4,6 +4,7 @@ crypto-obj-y += aes.o
 crypto-obj-y += desrfb.o
 crypto-obj-y += cipher.o
 crypto-obj-y += tlscreds.o
+crypto-obj-y += tlscredsanon.o
 
 # Let the userspace emulators avoid linking gnutls/etc
 crypto-aes-obj-y = aes.o
diff --git a/crypto/tlscredsanon.c b/crypto/tlscredsanon.c
new file mode 100644
index 0000000000..c3fcdaff06
--- /dev/null
+++ b/crypto/tlscredsanon.c
@@ -0,0 +1,223 @@
+/*
+ * QEMU crypto TLS anonymous credential support
+ *
+ * Copyright (c) 2015 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "crypto/tlscredsanon.h"
+#include "crypto/tlscredspriv.h"
+#include "qom/object_interfaces.h"
+#include "trace.h"
+
+
+#ifdef CONFIG_GNUTLS
+
+
+static int
+qcrypto_tls_creds_anon_load(QCryptoTLSCredsAnon *creds,
+                            Error **errp)
+{
+    char *dhparams = NULL;
+    int ret;
+    int rv = -1;
+
+    trace_qcrypto_tls_creds_anon_load(creds,
+            creds->parent_obj.dir ? creds->parent_obj.dir : "<nodir>");
+
+    if (creds->parent_obj.endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
+        if (qcrypto_tls_creds_get_path(&creds->parent_obj,
+                                       QCRYPTO_TLS_CREDS_DH_PARAMS,
+                                       false, &dhparams, errp) < 0) {
+            goto cleanup;
+        }
+
+        ret = gnutls_anon_allocate_server_credentials(&creds->data.server);
+        if (ret < 0) {
+            error_setg(errp, "Cannot allocate credentials: %s",
+                       gnutls_strerror(ret));
+            goto cleanup;
+        }
+
+        if (qcrypto_tls_creds_get_dh_params_file(&creds->parent_obj, dhparams,
+                                                 &creds->parent_obj.dh_params,
+                                                 errp) < 0) {
+            goto cleanup;
+        }
+
+        gnutls_anon_set_server_dh_params(creds->data.server,
+                                         creds->parent_obj.dh_params);
+    } else {
+        ret = gnutls_anon_allocate_client_credentials(&creds->data.client);
+        if (ret < 0) {
+            error_setg(errp, "Cannot allocate credentials: %s",
+                       gnutls_strerror(ret));
+            goto cleanup;
+        }
+    }
+
+    rv = 0;
+ cleanup:
+    g_free(dhparams);
+    return rv;
+}
+
+
+static void
+qcrypto_tls_creds_anon_unload(QCryptoTLSCredsAnon *creds)
+{
+    if (creds->parent_obj.endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_CLIENT) {
+        if (creds->data.client) {
+            gnutls_anon_free_client_credentials(creds->data.client);
+            creds->data.client = NULL;
+        }
+    } else {
+        if (creds->data.server) {
+            gnutls_anon_free_server_credentials(creds->data.server);
+            creds->data.server = NULL;
+        }
+    }
+    if (creds->parent_obj.dh_params) {
+        gnutls_dh_params_deinit(creds->parent_obj.dh_params);
+        creds->parent_obj.dh_params = NULL;
+    }
+}
+
+#else /* ! CONFIG_GNUTLS */
+
+
+static void
+qcrypto_tls_creds_anon_load(QCryptoTLSCredsAnon *creds G_GNUC_UNUSED,
+                            Error **errp)
+{
+    error_setg(errp, "TLS credentials support requires GNUTLS");
+}
+
+
+static void
+qcrypto_tls_creds_anon_unload(QCryptoTLSCredsAnon *creds G_GNUC_UNUSED)
+{
+    /* nada */
+}
+
+
+#endif /* ! CONFIG_GNUTLS */
+
+
+static void
+qcrypto_tls_creds_anon_prop_set_loaded(Object *obj,
+                                       bool value,
+                                       Error **errp)
+{
+    QCryptoTLSCredsAnon *creds = QCRYPTO_TLS_CREDS_ANON(obj);
+
+    if (value) {
+        qcrypto_tls_creds_anon_load(creds, errp);
+    } else {
+        qcrypto_tls_creds_anon_unload(creds);
+    }
+}
+
+
+#ifdef CONFIG_GNUTLS
+
+
+static bool
+qcrypto_tls_creds_anon_prop_get_loaded(Object *obj,
+                                       Error **errp G_GNUC_UNUSED)
+{
+    QCryptoTLSCredsAnon *creds = QCRYPTO_TLS_CREDS_ANON(obj);
+
+    if (creds->parent_obj.endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
+        return creds->data.server != NULL;
+    } else {
+        return creds->data.client != NULL;
+    }
+}
+
+
+#else /* ! CONFIG_GNUTLS */
+
+
+static bool
+qcrypto_tls_creds_anon_prop_get_loaded(Object *obj G_GNUC_UNUSED,
+                                       Error **errp G_GNUC_UNUSED)
+{
+    return false;
+}
+
+
+#endif /* ! CONFIG_GNUTLS */
+
+
+static void
+qcrypto_tls_creds_anon_complete(UserCreatable *uc, Error **errp)
+{
+    object_property_set_bool(OBJECT(uc), true, "loaded", errp);
+}
+
+
+static void
+qcrypto_tls_creds_anon_init(Object *obj)
+{
+    object_property_add_bool(obj, "loaded",
+                             qcrypto_tls_creds_anon_prop_get_loaded,
+                             qcrypto_tls_creds_anon_prop_set_loaded,
+                             NULL);
+}
+
+
+static void
+qcrypto_tls_creds_anon_finalize(Object *obj)
+{
+    QCryptoTLSCredsAnon *creds = QCRYPTO_TLS_CREDS_ANON(obj);
+
+    qcrypto_tls_creds_anon_unload(creds);
+}
+
+
+static void
+qcrypto_tls_creds_anon_class_init(ObjectClass *oc, void *data)
+{
+    UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);
+
+    ucc->complete = qcrypto_tls_creds_anon_complete;
+}
+
+
+static const TypeInfo qcrypto_tls_creds_anon_info = {
+    .parent = TYPE_QCRYPTO_TLS_CREDS,
+    .name = TYPE_QCRYPTO_TLS_CREDS_ANON,
+    .instance_size = sizeof(QCryptoTLSCredsAnon),
+    .instance_init = qcrypto_tls_creds_anon_init,
+    .instance_finalize = qcrypto_tls_creds_anon_finalize,
+    .class_size = sizeof(QCryptoTLSCredsAnonClass),
+    .class_init = qcrypto_tls_creds_anon_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_USER_CREATABLE },
+        { }
+    }
+};
+
+
+static void
+qcrypto_tls_creds_anon_register_types(void)
+{
+    type_register_static(&qcrypto_tls_creds_anon_info);
+}
+
+
+type_init(qcrypto_tls_creds_anon_register_types);