qemu/crypto/tlscreds.c
Daniel P. Berrange 13f12430d4 crypto: add support for TLS priority string override
The gnutls default priority is either "NORMAL" (most historical
versions of gnutls) which is a built-in label in gnutls code,
or "@SYSTEM" (latest gnutls on Fedora at least) which refers
to an admin customizable entry in a gnutls config file.

Regardless of which default is used by a distro, they are both
global defaults applying to all applications using gnutls. If
a single application on the system needs to use a weaker set
of crypto priorities, this potentially forces the weakness onto
all applications. Or conversely if a single application wants a
strong default than all others, it can't do this via the global
config file.

This adds an extra parameter to the tls credential object which
allows the mgmt app / user to explicitly provide a priority
string to QEMU when configuring TLS.

For example, to use the "NORMAL" priority, but disable SSL 3.0
one can now configure QEMU thus:

  $QEMU -object tls-creds-x509,id=tls0,dir=/home/berrange/qemutls,\
                priority="NORMAL:-VERS-SSL3.0" \
        ..other args...

If creating tls-creds-anon, whatever priority the user specifies
will always have "+ANON-DH" appended to it, since that's mandatory
to make the anonymous credentials work.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2016-07-04 15:52:43 +01:00

286 lines
7.8 KiB
C

/*
* QEMU crypto TLS 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 "qemu/osdep.h"
#include "qapi/error.h"
#include "crypto/tlscredspriv.h"
#include "trace.h"
#define DH_BITS 2048
#ifdef CONFIG_GNUTLS
int
qcrypto_tls_creds_get_dh_params_file(QCryptoTLSCreds *creds,
const char *filename,
gnutls_dh_params_t *dh_params,
Error **errp)
{
int ret;
trace_qcrypto_tls_creds_load_dh(creds, filename ? filename : "<generated>");
if (filename == NULL) {
ret = gnutls_dh_params_init(dh_params);
if (ret < 0) {
error_setg(errp, "Unable to initialize DH parameters: %s",
gnutls_strerror(ret));
return -1;
}
ret = gnutls_dh_params_generate2(*dh_params, DH_BITS);
if (ret < 0) {
gnutls_dh_params_deinit(*dh_params);
*dh_params = NULL;
error_setg(errp, "Unable to generate DH parameters: %s",
gnutls_strerror(ret));
return -1;
}
} else {
GError *gerr = NULL;
gchar *contents;
gsize len;
gnutls_datum_t data;
if (!g_file_get_contents(filename,
&contents,
&len,
&gerr)) {
error_setg(errp, "%s", gerr->message);
g_error_free(gerr);
return -1;
}
data.data = (unsigned char *)contents;
data.size = len;
ret = gnutls_dh_params_init(dh_params);
if (ret < 0) {
g_free(contents);
error_setg(errp, "Unable to initialize DH parameters: %s",
gnutls_strerror(ret));
return -1;
}
ret = gnutls_dh_params_import_pkcs3(*dh_params,
&data,
GNUTLS_X509_FMT_PEM);
g_free(contents);
if (ret < 0) {
gnutls_dh_params_deinit(*dh_params);
*dh_params = NULL;
error_setg(errp, "Unable to load DH parameters from %s: %s",
filename, gnutls_strerror(ret));
return -1;
}
}
return 0;
}
int
qcrypto_tls_creds_get_path(QCryptoTLSCreds *creds,
const char *filename,
bool required,
char **cred,
Error **errp)
{
struct stat sb;
int ret = -1;
if (!creds->dir) {
if (required) {
error_setg(errp, "Missing 'dir' property value");
return -1;
} else {
return 0;
}
}
*cred = g_strdup_printf("%s/%s", creds->dir, filename);
if (stat(*cred, &sb) < 0) {
if (errno == ENOENT && !required) {
ret = 0;
} else {
error_setg_errno(errp, errno,
"Unable to access credentials %s",
*cred);
}
g_free(*cred);
*cred = NULL;
goto cleanup;
}
ret = 0;
cleanup:
trace_qcrypto_tls_creds_get_path(creds, filename,
*cred ? *cred : "<none>");
return ret;
}
#endif /* ! CONFIG_GNUTLS */
static void
qcrypto_tls_creds_prop_set_verify(Object *obj,
bool value,
Error **errp G_GNUC_UNUSED)
{
QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
creds->verifyPeer = value;
}
static bool
qcrypto_tls_creds_prop_get_verify(Object *obj,
Error **errp G_GNUC_UNUSED)
{
QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
return creds->verifyPeer;
}
static void
qcrypto_tls_creds_prop_set_dir(Object *obj,
const char *value,
Error **errp G_GNUC_UNUSED)
{
QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
creds->dir = g_strdup(value);
}
static char *
qcrypto_tls_creds_prop_get_dir(Object *obj,
Error **errp G_GNUC_UNUSED)
{
QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
return g_strdup(creds->dir);
}
static void
qcrypto_tls_creds_prop_set_priority(Object *obj,
const char *value,
Error **errp G_GNUC_UNUSED)
{
QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
creds->priority = g_strdup(value);
}
static char *
qcrypto_tls_creds_prop_get_priority(Object *obj,
Error **errp G_GNUC_UNUSED)
{
QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
return g_strdup(creds->priority);
}
static void
qcrypto_tls_creds_prop_set_endpoint(Object *obj,
int value,
Error **errp G_GNUC_UNUSED)
{
QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
creds->endpoint = value;
}
static int
qcrypto_tls_creds_prop_get_endpoint(Object *obj,
Error **errp G_GNUC_UNUSED)
{
QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
return creds->endpoint;
}
static void
qcrypto_tls_creds_class_init(ObjectClass *oc, void *data)
{
object_class_property_add_bool(oc, "verify-peer",
qcrypto_tls_creds_prop_get_verify,
qcrypto_tls_creds_prop_set_verify,
NULL);
object_class_property_add_str(oc, "dir",
qcrypto_tls_creds_prop_get_dir,
qcrypto_tls_creds_prop_set_dir,
NULL);
object_class_property_add_enum(oc, "endpoint",
"QCryptoTLSCredsEndpoint",
QCryptoTLSCredsEndpoint_lookup,
qcrypto_tls_creds_prop_get_endpoint,
qcrypto_tls_creds_prop_set_endpoint,
NULL);
object_class_property_add_str(oc, "priority",
qcrypto_tls_creds_prop_get_priority,
qcrypto_tls_creds_prop_set_priority,
NULL);
}
static void
qcrypto_tls_creds_init(Object *obj)
{
QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
creds->verifyPeer = true;
}
static void
qcrypto_tls_creds_finalize(Object *obj)
{
QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
g_free(creds->dir);
g_free(creds->priority);
}
static const TypeInfo qcrypto_tls_creds_info = {
.parent = TYPE_OBJECT,
.name = TYPE_QCRYPTO_TLS_CREDS,
.instance_size = sizeof(QCryptoTLSCreds),
.instance_init = qcrypto_tls_creds_init,
.instance_finalize = qcrypto_tls_creds_finalize,
.class_init = qcrypto_tls_creds_class_init,
.class_size = sizeof(QCryptoTLSCredsClass),
.abstract = true,
};
static void
qcrypto_tls_creds_register_types(void)
{
type_register_static(&qcrypto_tls_creds_info);
}
type_init(qcrypto_tls_creds_register_types);