mirror of
https://github.com/kasmtech/KasmVNC.git
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446 lines
13 KiB
C++
446 lines
13 KiB
C++
/*
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* Copyright (C) 2004 Red Hat Inc.
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* Copyright (C) 2005 Martin Koegler
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* Copyright (C) 2010 TigerVNC Team
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* Copyright (C) 2010 m-privacy GmbH
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*
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* This is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This software 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
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this software; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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* USA.
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#ifndef HAVE_GNUTLS
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#error "This header should not be compiled without HAVE_GNUTLS defined"
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#endif
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#include <stdlib.h>
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#ifndef WIN32
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#include <unistd.h>
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#endif
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#include <rfb/CSecurityTLS.h>
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#include <rfb/SSecurityVeNCrypt.h>
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#include <rfb/CConnection.h>
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#include <rfb/LogWriter.h>
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#include <rfb/Exception.h>
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#include <rfb/UserMsgBox.h>
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#include <rdr/TLSInStream.h>
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#include <rdr/TLSOutStream.h>
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#include <os/os.h>
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#include <gnutls/x509.h>
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/*
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* GNUTLS 2.6.5 and older didn't have some variables defined so don't use them.
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* GNUTLS 1.X.X defined LIBGNUTLS_VERSION_NUMBER so treat it as "old" gnutls as
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* well
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*/
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#if (defined(GNUTLS_VERSION_NUMBER) && GNUTLS_VERSION_NUMBER < 0x020606) || \
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defined(LIBGNUTLS_VERSION_NUMBER)
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#define WITHOUT_X509_TIMES
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#endif
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/* Ancient GNUTLS... */
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#if !defined(GNUTLS_VERSION_NUMBER) && !defined(LIBGNUTLS_VERSION_NUMBER)
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#define WITHOUT_X509_TIMES
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#endif
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using namespace rfb;
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StringParameter CSecurityTLS::X509CA("X509CA", "X509 CA certificate", "", ConfViewer);
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StringParameter CSecurityTLS::X509CRL("X509CRL", "X509 CRL file", "", ConfViewer);
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static LogWriter vlog("TLS");
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CSecurityTLS::CSecurityTLS(bool _anon) : session(0), anon_cred(0),
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anon(_anon), fis(0), fos(0)
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{
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cafile = X509CA.getData();
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crlfile = X509CRL.getData();
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if (gnutls_global_init() != GNUTLS_E_SUCCESS)
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throw AuthFailureException("gnutls_global_init failed");
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}
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void CSecurityTLS::setDefaults()
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{
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char* homeDir = NULL;
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if (getvnchomedir(&homeDir) == -1) {
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vlog.error("Could not obtain VNC home directory path");
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return;
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}
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int len = strlen(homeDir) + 1;
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CharArray caDefault(len + 11);
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CharArray crlDefault(len + 12);
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sprintf(caDefault.buf, "%sx509_ca.pem", homeDir);
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sprintf(crlDefault.buf, "%s509_crl.pem", homeDir);
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delete [] homeDir;
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if (!fileexists(caDefault.buf))
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X509CA.setDefaultStr(strdup(caDefault.buf));
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if (!fileexists(crlDefault.buf))
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X509CRL.setDefaultStr(strdup(crlDefault.buf));
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}
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void CSecurityTLS::shutdown(bool needbye)
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{
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if (session && needbye)
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if (gnutls_bye(session, GNUTLS_SHUT_RDWR) != GNUTLS_E_SUCCESS)
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vlog.error("gnutls_bye failed");
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if (anon_cred) {
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gnutls_anon_free_client_credentials(anon_cred);
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anon_cred = 0;
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}
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if (cert_cred) {
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gnutls_certificate_free_credentials(cert_cred);
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cert_cred = 0;
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}
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if (session) {
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gnutls_deinit(session);
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session = 0;
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}
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}
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CSecurityTLS::~CSecurityTLS()
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{
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shutdown(true);
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if (fis)
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delete fis;
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if (fos)
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delete fos;
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delete[] cafile;
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delete[] crlfile;
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gnutls_global_deinit();
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}
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bool CSecurityTLS::processMsg(CConnection* cc)
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{
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rdr::InStream* is = cc->getInStream();
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rdr::OutStream* os = cc->getOutStream();
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client = cc;
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if (!session) {
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if (!is->checkNoWait(1))
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return false;
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if (is->readU8() == 0) {
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rdr::U32 result = is->readU32();
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CharArray reason;
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if (result == secResultFailed || result == secResultTooMany)
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reason.buf = is->readString();
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else
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reason.buf = strDup("protocol error");
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throw AuthFailureException(reason.buf);
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}
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if (gnutls_init(&session, GNUTLS_CLIENT) != GNUTLS_E_SUCCESS)
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throw AuthFailureException("gnutls_init failed");
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if (gnutls_set_default_priority(session) != GNUTLS_E_SUCCESS)
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throw AuthFailureException("gnutls_set_default_priority failed");
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setParam();
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}
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rdr::TLSInStream *tlsis = new rdr::TLSInStream(is, session);
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rdr::TLSOutStream *tlsos = new rdr::TLSOutStream(os, session);
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int err;
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err = gnutls_handshake(session);
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if (err != GNUTLS_E_SUCCESS) {
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delete tlsis;
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delete tlsos;
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if (!gnutls_error_is_fatal(err))
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return false;
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vlog.error("TLS Handshake failed: %s\n", gnutls_strerror (err));
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shutdown(false);
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throw AuthFailureException("TLS Handshake failed");
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}
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checkSession();
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cc->setStreams(fis = tlsis, fos = tlsos);
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return true;
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}
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void CSecurityTLS::setParam()
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{
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static const char kx_anon_priority[] = ":+ANON-ECDH:+ANON-DH";
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int ret;
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char *prio;
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const char *err;
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prio = (char*)malloc(strlen(Security::GnuTLSPriority) +
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strlen(kx_anon_priority) + 1);
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if (prio == NULL)
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throw AuthFailureException("Not enough memory for GnuTLS priority string");
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strcpy(prio, Security::GnuTLSPriority);
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if (anon)
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strcat(prio, kx_anon_priority);
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ret = gnutls_priority_set_direct(session, prio, &err);
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free(prio);
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if (ret != GNUTLS_E_SUCCESS) {
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if (ret == GNUTLS_E_INVALID_REQUEST)
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vlog.error("GnuTLS priority syntax error at: %s", err);
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throw AuthFailureException("gnutls_set_priority_direct failed");
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}
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if (anon) {
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if (gnutls_anon_allocate_client_credentials(&anon_cred) != GNUTLS_E_SUCCESS)
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throw AuthFailureException("gnutls_anon_allocate_client_credentials failed");
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if (gnutls_credentials_set(session, GNUTLS_CRD_ANON, anon_cred) != GNUTLS_E_SUCCESS)
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throw AuthFailureException("gnutls_credentials_set failed");
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vlog.debug("Anonymous session has been set");
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} else {
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if (gnutls_certificate_allocate_credentials(&cert_cred) != GNUTLS_E_SUCCESS)
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throw AuthFailureException("gnutls_certificate_allocate_credentials failed");
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if (*cafile && gnutls_certificate_set_x509_trust_file(cert_cred,cafile,GNUTLS_X509_FMT_PEM) < 0)
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throw AuthFailureException("load of CA cert failed");
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/* Load previously saved certs */
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char *homeDir = NULL;
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int err;
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if (getvnchomedir(&homeDir) == -1)
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vlog.error("Could not obtain VNC home directory path");
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else {
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CharArray caSave(strlen(homeDir) + 19 + 1);
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sprintf(caSave.buf, "%sx509_savedcerts.pem", homeDir);
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delete [] homeDir;
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err = gnutls_certificate_set_x509_trust_file(cert_cred, caSave.buf,
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GNUTLS_X509_FMT_PEM);
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if (err < 0)
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vlog.debug("Failed to load saved server certificates from %s", caSave.buf);
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}
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if (*crlfile && gnutls_certificate_set_x509_crl_file(cert_cred,crlfile,GNUTLS_X509_FMT_PEM) < 0)
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throw AuthFailureException("load of CRL failed");
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if (gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE, cert_cred) != GNUTLS_E_SUCCESS)
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throw AuthFailureException("gnutls_credentials_set failed");
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if (gnutls_server_name_set(session, GNUTLS_NAME_DNS,
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client->getServerName(),
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strlen(client->getServerName())) != GNUTLS_E_SUCCESS)
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vlog.error("Failed to configure the server name for TLS handshake");
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vlog.debug("X509 session has been set");
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}
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}
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void CSecurityTLS::checkSession()
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{
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const unsigned allowed_errors = GNUTLS_CERT_INVALID |
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GNUTLS_CERT_SIGNER_NOT_FOUND |
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GNUTLS_CERT_SIGNER_NOT_CA;
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unsigned int status;
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const gnutls_datum_t *cert_list;
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unsigned int cert_list_size = 0;
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int err;
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gnutls_datum_t info;
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if (anon)
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return;
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if (gnutls_certificate_type_get(session) != GNUTLS_CRT_X509)
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throw AuthFailureException("unsupported certificate type");
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err = gnutls_certificate_verify_peers2(session, &status);
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if (err != 0) {
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vlog.error("server certificate verification failed: %s", gnutls_strerror(err));
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throw AuthFailureException("server certificate verification failed");
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}
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if (status & GNUTLS_CERT_REVOKED)
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throw AuthFailureException("server certificate has been revoked");
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#ifndef WITHOUT_X509_TIMES
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if (status & GNUTLS_CERT_NOT_ACTIVATED)
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throw AuthFailureException("server certificate has not been activated");
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if (status & GNUTLS_CERT_EXPIRED) {
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vlog.debug("server certificate has expired");
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if (!msg->showMsgBox(UserMsgBox::M_YESNO, "certificate has expired",
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"The certificate of the server has expired, "
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"do you want to continue?"))
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throw AuthFailureException("server certificate has expired");
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}
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#endif
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/* Process other errors later */
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cert_list = gnutls_certificate_get_peers(session, &cert_list_size);
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if (!cert_list_size)
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throw AuthFailureException("empty certificate chain");
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/* Process only server's certificate, not issuer's certificate */
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gnutls_x509_crt_t crt;
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gnutls_x509_crt_init(&crt);
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if (gnutls_x509_crt_import(crt, &cert_list[0], GNUTLS_X509_FMT_DER) < 0)
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throw AuthFailureException("decoding of certificate failed");
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if (gnutls_x509_crt_check_hostname(crt, client->getServerName()) == 0) {
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char buf[255];
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vlog.debug("hostname mismatch");
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snprintf(buf, sizeof(buf), "Hostname (%s) does not match any certificate, "
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"do you want to continue?", client->getServerName());
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buf[sizeof(buf) - 1] = '\0';
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if (!msg->showMsgBox(UserMsgBox::M_YESNO, "hostname mismatch", buf))
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throw AuthFailureException("hostname mismatch");
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}
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if (status == 0) {
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/* Everything is fine (hostname + verification) */
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gnutls_x509_crt_deinit(crt);
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return;
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}
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if (status & GNUTLS_CERT_INVALID)
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vlog.debug("server certificate invalid");
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if (status & GNUTLS_CERT_SIGNER_NOT_FOUND)
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vlog.debug("server cert signer not found");
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if (status & GNUTLS_CERT_SIGNER_NOT_CA)
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vlog.debug("server cert signer not CA");
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if (status & GNUTLS_CERT_INSECURE_ALGORITHM)
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throw AuthFailureException("The server certificate uses an insecure algorithm");
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if ((status & (~allowed_errors)) != 0) {
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/* No other errors are allowed */
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vlog.debug("GNUTLS status of certificate verification: %u", status);
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throw AuthFailureException("Invalid status of server certificate verification");
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}
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vlog.debug("Saved server certificates don't match");
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if (gnutls_x509_crt_print(crt, GNUTLS_CRT_PRINT_ONELINE, &info)) {
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/*
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* GNUTLS doesn't correctly export gnutls_free symbol which is
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* a function pointer. Linking with Visual Studio 2008 Express will
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* fail when you call gnutls_free().
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*/
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#if WIN32
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free(info.data);
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#else
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gnutls_free(info.data);
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#endif
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throw AuthFailureException("Could not find certificate to display");
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}
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size_t out_size = 0;
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char *out_buf = NULL;
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char *certinfo = NULL;
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int len = 0;
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vlog.debug("certificate issuer unknown");
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len = snprintf(NULL, 0, "This certificate has been signed by an unknown "
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"authority:\n\n%s\n\nDo you want to save it and "
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"continue?\n ", info.data);
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if (len < 0)
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AuthFailureException("certificate decoding error");
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vlog.debug("%s", info.data);
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certinfo = new char[len];
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if (certinfo == NULL)
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throw AuthFailureException("Out of memory");
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snprintf(certinfo, len, "This certificate has been signed by an unknown "
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"authority:\n\n%s\n\nDo you want to save it and "
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"continue? ", info.data);
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for (int i = 0; i < len - 1; i++)
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if (certinfo[i] == ',' && certinfo[i + 1] == ' ')
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certinfo[i] = '\n';
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if (!msg->showMsgBox(UserMsgBox::M_YESNO, "certificate issuer unknown",
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certinfo)) {
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delete [] certinfo;
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throw AuthFailureException("certificate issuer unknown");
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}
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delete [] certinfo;
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if (gnutls_x509_crt_export(crt, GNUTLS_X509_FMT_PEM, NULL, &out_size)
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== GNUTLS_E_SHORT_MEMORY_BUFFER)
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AuthFailureException("Out of memory");
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// Save cert
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out_buf = new char[out_size];
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if (out_buf == NULL)
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AuthFailureException("Out of memory");
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if (gnutls_x509_crt_export(crt, GNUTLS_X509_FMT_PEM, out_buf, &out_size) < 0)
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AuthFailureException("certificate issuer unknown, and certificate "
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"export failed");
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char *homeDir = NULL;
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if (getvnchomedir(&homeDir) == -1)
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vlog.error("Could not obtain VNC home directory path");
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else {
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FILE *f;
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CharArray caSave(strlen(homeDir) + 1 + 19);
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sprintf(caSave.buf, "%sx509_savedcerts.pem", homeDir);
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delete [] homeDir;
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f = fopen(caSave.buf, "a+");
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if (!f)
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msg->showMsgBox(UserMsgBox::M_OK, "certificate save failed",
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"Could not save the certificate");
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else {
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fprintf(f, "%s\n", out_buf);
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fclose(f);
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}
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}
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delete [] out_buf;
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gnutls_x509_crt_deinit(crt);
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/*
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* GNUTLS doesn't correctly export gnutls_free symbol which is
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* a function pointer. Linking with Visual Studio 2008 Express will
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* fail when you call gnutls_free().
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*/
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#if WIN32
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free(info.data);
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#else
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gnutls_free(info.data);
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#endif
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}
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