Pre-Shared Keys (PSK) is a simpler mechanism for enabling TLS connections than using certificates. It requires only a simple secret key: $ mkdir -m 0700 /tmp/keys $ psktool -u rjones -p /tmp/keys/keys.psk $ cat /tmp/keys/keys.psk rjones:d543770c15ad93d76443fb56f501a31969235f47e999720ae8d2336f6a13fcbc The key can be secretly shared between clients and servers. Clients must specify the directory containing the "keys.psk" file and a username (defaults to "qemu"). Servers must specify only the directory. Example NBD client: $ qemu-img info \ --object tls-creds-psk,id=tls0,dir=/tmp/keys,username=rjones,endpoint=client \ --image-opts \ file.driver=nbd,file.host=localhost,file.port=10809,file.tls-creds=tls0,file.export=/ Example NBD server using qemu-nbd: $ qemu-nbd -t -x / \ --object tls-creds-psk,id=tls0,endpoint=server,dir=/tmp/keys \ --tls-creds tls0 \ image.qcow2 Example NBD server using nbdkit: $ nbdkit -n -e / -fv \ --tls=on --tls-psk=/tmp/keys/keys.psk \ file file=disk.img Signed-off-by: Richard W.M. Jones <rjones@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
647 lines
18 KiB
C
647 lines
18 KiB
C
/*
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* QEMU crypto TLS session support
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*
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* Copyright (c) 2015 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include "qemu/osdep.h"
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#include "crypto/tlssession.h"
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#include "crypto/tlscredsanon.h"
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#include "crypto/tlscredspsk.h"
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#include "crypto/tlscredsx509.h"
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#include "qapi/error.h"
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#include "qemu/acl.h"
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#include "trace.h"
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#ifdef CONFIG_GNUTLS
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#include <gnutls/x509.h>
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struct QCryptoTLSSession {
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QCryptoTLSCreds *creds;
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gnutls_session_t handle;
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char *hostname;
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char *aclname;
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bool handshakeComplete;
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QCryptoTLSSessionWriteFunc writeFunc;
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QCryptoTLSSessionReadFunc readFunc;
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void *opaque;
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char *peername;
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};
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void
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qcrypto_tls_session_free(QCryptoTLSSession *session)
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{
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if (!session) {
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return;
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}
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gnutls_deinit(session->handle);
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g_free(session->hostname);
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g_free(session->peername);
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g_free(session->aclname);
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object_unref(OBJECT(session->creds));
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g_free(session);
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}
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static ssize_t
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qcrypto_tls_session_push(void *opaque, const void *buf, size_t len)
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{
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QCryptoTLSSession *session = opaque;
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if (!session->writeFunc) {
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errno = EIO;
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return -1;
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};
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return session->writeFunc(buf, len, session->opaque);
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}
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static ssize_t
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qcrypto_tls_session_pull(void *opaque, void *buf, size_t len)
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{
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QCryptoTLSSession *session = opaque;
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if (!session->readFunc) {
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errno = EIO;
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return -1;
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};
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return session->readFunc(buf, len, session->opaque);
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}
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#define TLS_PRIORITY_ADDITIONAL_ANON "+ANON-DH"
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#if GNUTLS_VERSION_MAJOR >= 3
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#define TLS_ECDHE_PSK "+ECDHE-PSK:"
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#else
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#define TLS_ECDHE_PSK ""
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#endif
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#define TLS_PRIORITY_ADDITIONAL_PSK TLS_ECDHE_PSK "+DHE-PSK:+PSK"
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QCryptoTLSSession *
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qcrypto_tls_session_new(QCryptoTLSCreds *creds,
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const char *hostname,
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const char *aclname,
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QCryptoTLSCredsEndpoint endpoint,
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Error **errp)
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{
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QCryptoTLSSession *session;
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int ret;
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session = g_new0(QCryptoTLSSession, 1);
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trace_qcrypto_tls_session_new(
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session, creds, hostname ? hostname : "<none>",
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aclname ? aclname : "<none>", endpoint);
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if (hostname) {
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session->hostname = g_strdup(hostname);
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}
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if (aclname) {
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session->aclname = g_strdup(aclname);
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}
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session->creds = creds;
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object_ref(OBJECT(creds));
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if (creds->endpoint != endpoint) {
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error_setg(errp, "Credentials endpoint doesn't match session");
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goto error;
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}
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if (endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
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ret = gnutls_init(&session->handle, GNUTLS_SERVER);
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} else {
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ret = gnutls_init(&session->handle, GNUTLS_CLIENT);
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}
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if (ret < 0) {
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error_setg(errp, "Cannot initialize TLS session: %s",
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gnutls_strerror(ret));
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goto error;
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}
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if (object_dynamic_cast(OBJECT(creds),
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TYPE_QCRYPTO_TLS_CREDS_ANON)) {
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QCryptoTLSCredsAnon *acreds = QCRYPTO_TLS_CREDS_ANON(creds);
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char *prio;
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if (creds->priority != NULL) {
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prio = g_strdup_printf("%s:%s",
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creds->priority,
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TLS_PRIORITY_ADDITIONAL_ANON);
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} else {
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prio = g_strdup(CONFIG_TLS_PRIORITY ":"
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TLS_PRIORITY_ADDITIONAL_ANON);
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}
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ret = gnutls_priority_set_direct(session->handle, prio, NULL);
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if (ret < 0) {
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error_setg(errp, "Unable to set TLS session priority %s: %s",
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prio, gnutls_strerror(ret));
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g_free(prio);
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goto error;
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}
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g_free(prio);
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if (creds->endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
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ret = gnutls_credentials_set(session->handle,
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GNUTLS_CRD_ANON,
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acreds->data.server);
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} else {
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ret = gnutls_credentials_set(session->handle,
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GNUTLS_CRD_ANON,
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acreds->data.client);
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}
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if (ret < 0) {
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error_setg(errp, "Cannot set session credentials: %s",
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gnutls_strerror(ret));
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goto error;
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}
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} else if (object_dynamic_cast(OBJECT(creds),
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TYPE_QCRYPTO_TLS_CREDS_PSK)) {
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QCryptoTLSCredsPSK *pcreds = QCRYPTO_TLS_CREDS_PSK(creds);
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char *prio;
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if (creds->priority != NULL) {
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prio = g_strdup_printf("%s:%s",
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creds->priority,
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TLS_PRIORITY_ADDITIONAL_PSK);
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} else {
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prio = g_strdup(CONFIG_TLS_PRIORITY ":"
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TLS_PRIORITY_ADDITIONAL_PSK);
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}
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ret = gnutls_priority_set_direct(session->handle, prio, NULL);
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if (ret < 0) {
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error_setg(errp, "Unable to set TLS session priority %s: %s",
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prio, gnutls_strerror(ret));
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g_free(prio);
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goto error;
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}
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g_free(prio);
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if (creds->endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
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ret = gnutls_credentials_set(session->handle,
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GNUTLS_CRD_PSK,
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pcreds->data.server);
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} else {
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ret = gnutls_credentials_set(session->handle,
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GNUTLS_CRD_PSK,
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pcreds->data.client);
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}
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if (ret < 0) {
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error_setg(errp, "Cannot set session credentials: %s",
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gnutls_strerror(ret));
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goto error;
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}
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} else if (object_dynamic_cast(OBJECT(creds),
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TYPE_QCRYPTO_TLS_CREDS_X509)) {
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QCryptoTLSCredsX509 *tcreds = QCRYPTO_TLS_CREDS_X509(creds);
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const char *prio = creds->priority;
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if (!prio) {
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prio = CONFIG_TLS_PRIORITY;
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}
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ret = gnutls_priority_set_direct(session->handle, prio, NULL);
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if (ret < 0) {
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error_setg(errp, "Cannot set default TLS session priority %s: %s",
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prio, gnutls_strerror(ret));
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goto error;
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}
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ret = gnutls_credentials_set(session->handle,
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GNUTLS_CRD_CERTIFICATE,
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tcreds->data);
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if (ret < 0) {
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error_setg(errp, "Cannot set session credentials: %s",
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gnutls_strerror(ret));
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goto error;
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}
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if (creds->endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
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/* This requests, but does not enforce a client cert.
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* The cert checking code later does enforcement */
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gnutls_certificate_server_set_request(session->handle,
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GNUTLS_CERT_REQUEST);
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}
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} else {
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error_setg(errp, "Unsupported TLS credentials type %s",
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object_get_typename(OBJECT(creds)));
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goto error;
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}
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gnutls_transport_set_ptr(session->handle, session);
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gnutls_transport_set_push_function(session->handle,
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qcrypto_tls_session_push);
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gnutls_transport_set_pull_function(session->handle,
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qcrypto_tls_session_pull);
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return session;
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error:
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qcrypto_tls_session_free(session);
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return NULL;
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}
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static int
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qcrypto_tls_session_check_certificate(QCryptoTLSSession *session,
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Error **errp)
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{
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int ret;
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unsigned int status;
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const gnutls_datum_t *certs;
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unsigned int nCerts, i;
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time_t now;
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gnutls_x509_crt_t cert = NULL;
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now = time(NULL);
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if (now == ((time_t)-1)) {
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error_setg_errno(errp, errno, "Cannot get current time");
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return -1;
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}
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ret = gnutls_certificate_verify_peers2(session->handle, &status);
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if (ret < 0) {
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error_setg(errp, "Verify failed: %s", gnutls_strerror(ret));
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return -1;
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}
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if (status != 0) {
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const char *reason = "Invalid certificate";
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if (status & GNUTLS_CERT_INVALID) {
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reason = "The certificate is not trusted";
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}
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if (status & GNUTLS_CERT_SIGNER_NOT_FOUND) {
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reason = "The certificate hasn't got a known issuer";
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}
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if (status & GNUTLS_CERT_REVOKED) {
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reason = "The certificate has been revoked";
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}
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if (status & GNUTLS_CERT_INSECURE_ALGORITHM) {
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reason = "The certificate uses an insecure algorithm";
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}
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error_setg(errp, "%s", reason);
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return -1;
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}
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certs = gnutls_certificate_get_peers(session->handle, &nCerts);
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if (!certs) {
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error_setg(errp, "No certificate peers");
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return -1;
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}
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for (i = 0; i < nCerts; i++) {
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ret = gnutls_x509_crt_init(&cert);
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if (ret < 0) {
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error_setg(errp, "Cannot initialize certificate: %s",
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gnutls_strerror(ret));
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return -1;
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}
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ret = gnutls_x509_crt_import(cert, &certs[i], GNUTLS_X509_FMT_DER);
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if (ret < 0) {
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error_setg(errp, "Cannot import certificate: %s",
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gnutls_strerror(ret));
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goto error;
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}
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if (gnutls_x509_crt_get_expiration_time(cert) < now) {
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error_setg(errp, "The certificate has expired");
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goto error;
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}
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if (gnutls_x509_crt_get_activation_time(cert) > now) {
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error_setg(errp, "The certificate is not yet activated");
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goto error;
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}
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if (gnutls_x509_crt_get_activation_time(cert) > now) {
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error_setg(errp, "The certificate is not yet activated");
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goto error;
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}
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if (i == 0) {
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size_t dnameSize = 1024;
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session->peername = g_malloc(dnameSize);
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requery:
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ret = gnutls_x509_crt_get_dn(cert, session->peername, &dnameSize);
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if (ret < 0) {
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if (ret == GNUTLS_E_SHORT_MEMORY_BUFFER) {
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session->peername = g_realloc(session->peername,
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dnameSize);
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goto requery;
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}
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error_setg(errp, "Cannot get client distinguished name: %s",
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gnutls_strerror(ret));
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goto error;
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}
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if (session->aclname) {
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qemu_acl *acl = qemu_acl_find(session->aclname);
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int allow;
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if (!acl) {
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error_setg(errp, "Cannot find ACL %s",
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session->aclname);
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goto error;
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}
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allow = qemu_acl_party_is_allowed(acl, session->peername);
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if (!allow) {
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error_setg(errp, "TLS x509 ACL check for %s is denied",
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session->peername);
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goto error;
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}
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}
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if (session->hostname) {
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if (!gnutls_x509_crt_check_hostname(cert, session->hostname)) {
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error_setg(errp,
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"Certificate does not match the hostname %s",
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session->hostname);
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goto error;
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}
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}
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}
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gnutls_x509_crt_deinit(cert);
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}
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return 0;
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error:
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gnutls_x509_crt_deinit(cert);
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return -1;
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}
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int
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qcrypto_tls_session_check_credentials(QCryptoTLSSession *session,
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Error **errp)
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{
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if (object_dynamic_cast(OBJECT(session->creds),
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TYPE_QCRYPTO_TLS_CREDS_ANON)) {
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trace_qcrypto_tls_session_check_creds(session, "nop");
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return 0;
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} else if (object_dynamic_cast(OBJECT(session->creds),
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TYPE_QCRYPTO_TLS_CREDS_PSK)) {
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trace_qcrypto_tls_session_check_creds(session, "nop");
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return 0;
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} else if (object_dynamic_cast(OBJECT(session->creds),
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TYPE_QCRYPTO_TLS_CREDS_X509)) {
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if (session->creds->verifyPeer) {
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int ret = qcrypto_tls_session_check_certificate(session,
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errp);
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trace_qcrypto_tls_session_check_creds(session,
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ret == 0 ? "pass" : "fail");
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return ret;
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} else {
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trace_qcrypto_tls_session_check_creds(session, "skip");
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return 0;
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}
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} else {
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trace_qcrypto_tls_session_check_creds(session, "error");
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error_setg(errp, "Unexpected credential type %s",
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object_get_typename(OBJECT(session->creds)));
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return -1;
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}
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}
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void
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qcrypto_tls_session_set_callbacks(QCryptoTLSSession *session,
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QCryptoTLSSessionWriteFunc writeFunc,
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QCryptoTLSSessionReadFunc readFunc,
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void *opaque)
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{
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session->writeFunc = writeFunc;
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session->readFunc = readFunc;
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session->opaque = opaque;
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}
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|
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ssize_t
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qcrypto_tls_session_write(QCryptoTLSSession *session,
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const char *buf,
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size_t len)
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{
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ssize_t ret = gnutls_record_send(session->handle, buf, len);
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|
|
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if (ret < 0) {
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switch (ret) {
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case GNUTLS_E_AGAIN:
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errno = EAGAIN;
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break;
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case GNUTLS_E_INTERRUPTED:
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errno = EINTR;
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break;
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default:
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errno = EIO;
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break;
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}
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ret = -1;
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}
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return ret;
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|
}
|
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|
|
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ssize_t
|
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qcrypto_tls_session_read(QCryptoTLSSession *session,
|
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char *buf,
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size_t len)
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{
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ssize_t ret = gnutls_record_recv(session->handle, buf, len);
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|
|
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if (ret < 0) {
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switch (ret) {
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case GNUTLS_E_AGAIN:
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errno = EAGAIN;
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break;
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|
case GNUTLS_E_INTERRUPTED:
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errno = EINTR;
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break;
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|
default:
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errno = EIO;
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break;
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}
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ret = -1;
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}
|
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return ret;
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|
}
|
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|
|
|
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int
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qcrypto_tls_session_handshake(QCryptoTLSSession *session,
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Error **errp)
|
|
{
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|
int ret = gnutls_handshake(session->handle);
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if (ret == 0) {
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|
session->handshakeComplete = true;
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|
} else {
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if (ret == GNUTLS_E_INTERRUPTED ||
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ret == GNUTLS_E_AGAIN) {
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|
ret = 1;
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|
} else {
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error_setg(errp, "TLS handshake failed: %s",
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gnutls_strerror(ret));
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|
ret = -1;
|
|
}
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
|
|
QCryptoTLSSessionHandshakeStatus
|
|
qcrypto_tls_session_get_handshake_status(QCryptoTLSSession *session)
|
|
{
|
|
if (session->handshakeComplete) {
|
|
return QCRYPTO_TLS_HANDSHAKE_COMPLETE;
|
|
} else if (gnutls_record_get_direction(session->handle) == 0) {
|
|
return QCRYPTO_TLS_HANDSHAKE_RECVING;
|
|
} else {
|
|
return QCRYPTO_TLS_HANDSHAKE_SENDING;
|
|
}
|
|
}
|
|
|
|
|
|
int
|
|
qcrypto_tls_session_get_key_size(QCryptoTLSSession *session,
|
|
Error **errp)
|
|
{
|
|
gnutls_cipher_algorithm_t cipher;
|
|
int ssf;
|
|
|
|
cipher = gnutls_cipher_get(session->handle);
|
|
ssf = gnutls_cipher_get_key_size(cipher);
|
|
if (!ssf) {
|
|
error_setg(errp, "Cannot get TLS cipher key size");
|
|
return -1;
|
|
}
|
|
return ssf;
|
|
}
|
|
|
|
|
|
char *
|
|
qcrypto_tls_session_get_peer_name(QCryptoTLSSession *session)
|
|
{
|
|
if (session->peername) {
|
|
return g_strdup(session->peername);
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
|
|
#else /* ! CONFIG_GNUTLS */
|
|
|
|
|
|
QCryptoTLSSession *
|
|
qcrypto_tls_session_new(QCryptoTLSCreds *creds G_GNUC_UNUSED,
|
|
const char *hostname G_GNUC_UNUSED,
|
|
const char *aclname G_GNUC_UNUSED,
|
|
QCryptoTLSCredsEndpoint endpoint G_GNUC_UNUSED,
|
|
Error **errp)
|
|
{
|
|
error_setg(errp, "TLS requires GNUTLS support");
|
|
return NULL;
|
|
}
|
|
|
|
|
|
void
|
|
qcrypto_tls_session_free(QCryptoTLSSession *sess G_GNUC_UNUSED)
|
|
{
|
|
}
|
|
|
|
|
|
int
|
|
qcrypto_tls_session_check_credentials(QCryptoTLSSession *sess G_GNUC_UNUSED,
|
|
Error **errp)
|
|
{
|
|
error_setg(errp, "TLS requires GNUTLS support");
|
|
return -1;
|
|
}
|
|
|
|
|
|
void
|
|
qcrypto_tls_session_set_callbacks(
|
|
QCryptoTLSSession *sess G_GNUC_UNUSED,
|
|
QCryptoTLSSessionWriteFunc writeFunc G_GNUC_UNUSED,
|
|
QCryptoTLSSessionReadFunc readFunc G_GNUC_UNUSED,
|
|
void *opaque G_GNUC_UNUSED)
|
|
{
|
|
}
|
|
|
|
|
|
ssize_t
|
|
qcrypto_tls_session_write(QCryptoTLSSession *sess,
|
|
const char *buf,
|
|
size_t len)
|
|
{
|
|
errno = -EIO;
|
|
return -1;
|
|
}
|
|
|
|
|
|
ssize_t
|
|
qcrypto_tls_session_read(QCryptoTLSSession *sess,
|
|
char *buf,
|
|
size_t len)
|
|
{
|
|
errno = -EIO;
|
|
return -1;
|
|
}
|
|
|
|
|
|
int
|
|
qcrypto_tls_session_handshake(QCryptoTLSSession *sess,
|
|
Error **errp)
|
|
{
|
|
error_setg(errp, "TLS requires GNUTLS support");
|
|
return -1;
|
|
}
|
|
|
|
|
|
QCryptoTLSSessionHandshakeStatus
|
|
qcrypto_tls_session_get_handshake_status(QCryptoTLSSession *sess)
|
|
{
|
|
return QCRYPTO_TLS_HANDSHAKE_COMPLETE;
|
|
}
|
|
|
|
|
|
int
|
|
qcrypto_tls_session_get_key_size(QCryptoTLSSession *sess,
|
|
Error **errp)
|
|
{
|
|
error_setg(errp, "TLS requires GNUTLS support");
|
|
return -1;
|
|
}
|
|
|
|
|
|
char *
|
|
qcrypto_tls_session_get_peer_name(QCryptoTLSSession *sess)
|
|
{
|
|
return NULL;
|
|
}
|
|
|
|
#endif
|