Commit 13f12430 authored by Daniel P. Berrange's avatar Daniel P. Berrange

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: 's avatarDaniel P. Berrange <berrange@redhat.com>
parent 9164b897
......@@ -178,6 +178,27 @@ qcrypto_tls_creds_prop_get_dir(Object *obj,
}
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,
......@@ -216,6 +237,10 @@ qcrypto_tls_creds_class_init(ObjectClass *oc, void *data)
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);
}
......@@ -234,6 +259,7 @@ qcrypto_tls_creds_finalize(Object *obj)
QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
g_free(creds->dir);
g_free(creds->priority);
}
......
......@@ -132,14 +132,22 @@ qcrypto_tls_session_new(QCryptoTLSCreds *creds,
if (object_dynamic_cast(OBJECT(creds),
TYPE_QCRYPTO_TLS_CREDS_ANON)) {
QCryptoTLSCredsAnon *acreds = QCRYPTO_TLS_CREDS_ANON(creds);
char *prio;
ret = gnutls_priority_set_direct(session->handle,
"NORMAL:+ANON-DH", NULL);
if (creds->priority != NULL) {
prio = g_strdup_printf("%s:+ANON-DH", creds->priority);
} else {
prio = g_strdup("NORMAL:+ANON-DH");
}
ret = gnutls_priority_set_direct(session->handle, prio, NULL);
if (ret < 0) {
error_setg(errp, "Unable to set TLS session priority: %s",
gnutls_strerror(ret));
error_setg(errp, "Unable to set TLS session priority %s: %s",
prio, gnutls_strerror(ret));
g_free(prio);
goto error;
}
g_free(prio);
if (creds->endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
ret = gnutls_credentials_set(session->handle,
GNUTLS_CRD_ANON,
......@@ -157,11 +165,15 @@ qcrypto_tls_session_new(QCryptoTLSCreds *creds,
} else if (object_dynamic_cast(OBJECT(creds),
TYPE_QCRYPTO_TLS_CREDS_X509)) {
QCryptoTLSCredsX509 *tcreds = QCRYPTO_TLS_CREDS_X509(creds);
const char *prio = creds->priority;
if (!prio) {
prio = "NORMAL";
}
ret = gnutls_set_default_priority(session->handle);
ret = gnutls_priority_set_direct(session->handle, prio, NULL);
if (ret < 0) {
error_setg(errp, "Cannot set default TLS session priority: %s",
gnutls_strerror(ret));
error_setg(errp, "Cannot set default TLS session priority %s: %s",
prio, gnutls_strerror(ret));
goto error;
}
ret = gnutls_credentials_set(session->handle,
......
......@@ -54,6 +54,7 @@ struct QCryptoTLSCreds {
gnutls_dh_params_t dh_params;
#endif
bool verifyPeer;
char *priority;
};
......
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