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497 lines
13 KiB
497 lines
13 KiB
/*
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* Copyright (C) 2009 Vic Lee.
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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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#include <rfb/rfbclient.h>
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#include <errno.h>
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#include "tls.h"
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#ifdef LIBVNCSERVER_WITH_CLIENT_TLS
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static const int rfbCertTypePriority[] = { GNUTLS_CRT_X509, 0 };
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static const int rfbProtoPriority[]= { GNUTLS_TLS1_1, GNUTLS_TLS1_0, GNUTLS_SSL3, 0 };
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static const int rfbKXPriority[] = {GNUTLS_KX_DHE_DSS, GNUTLS_KX_RSA, GNUTLS_KX_DHE_RSA, GNUTLS_KX_SRP, 0};
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static const int rfbKXAnon[] = {GNUTLS_KX_ANON_DH, 0};
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#define DH_BITS 1024
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static gnutls_dh_params_t rfbDHParams;
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static rfbBool rfbTLSInitialized = FALSE;
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static rfbBool
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InitializeTLS(void)
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{
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int ret;
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if (rfbTLSInitialized) return TRUE;
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if ((ret = gnutls_global_init()) < 0 ||
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(ret = gnutls_dh_params_init(&rfbDHParams)) < 0 ||
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(ret = gnutls_dh_params_generate2(rfbDHParams, DH_BITS)) < 0)
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{
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rfbClientLog("Failed to initialized GnuTLS: %s.\n", gnutls_strerror(ret));
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return FALSE;
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}
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rfbClientLog("GnuTLS initialized.\n");
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rfbTLSInitialized = TRUE;
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return TRUE;
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}
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static ssize_t
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PushTLS(gnutls_transport_ptr_t transport, const void *data, size_t len)
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{
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rfbClient *client = (rfbClient*)transport;
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int ret;
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while (1)
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{
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ret = write(client->sock, data, len);
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if (ret < 0)
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{
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if (errno == EINTR) continue;
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return -1;
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}
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return ret;
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}
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}
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static ssize_t
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PullTLS(gnutls_transport_ptr_t transport, void *data, size_t len)
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{
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rfbClient *client = (rfbClient*)transport;
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int ret;
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while (1)
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{
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ret = read(client->sock, data, len);
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if (ret < 0)
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{
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if (errno == EINTR) continue;
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return -1;
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}
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return ret;
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}
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}
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static rfbBool
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InitializeTLSSession(rfbClient* client, rfbBool anonTLS)
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{
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int ret;
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if (client->tlsSession) return TRUE;
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if ((ret = gnutls_init(&client->tlsSession, GNUTLS_CLIENT)) < 0)
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{
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rfbClientLog("Failed to initialized TLS session: %s.\n", gnutls_strerror(ret));
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return FALSE;
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}
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if ((ret = gnutls_set_default_priority(client->tlsSession)) < 0 ||
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(ret = gnutls_kx_set_priority(client->tlsSession, anonTLS ? rfbKXAnon : rfbKXPriority)) < 0 ||
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(ret = gnutls_certificate_type_set_priority(client->tlsSession, rfbCertTypePriority)) < 0 ||
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(ret = gnutls_protocol_set_priority(client->tlsSession, rfbProtoPriority)) < 0)
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{
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FreeTLS(client);
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rfbClientLog("Failed to set TLS priority: %s.\n", gnutls_strerror(ret));
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return FALSE;
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}
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gnutls_transport_set_ptr(client->tlsSession, (gnutls_transport_ptr_t)client);
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gnutls_transport_set_push_function(client->tlsSession, PushTLS);
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gnutls_transport_set_pull_function(client->tlsSession, PullTLS);
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rfbClientLog("TLS session initialized.\n");
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return TRUE;
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}
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static rfbBool
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SetTLSAnonCredential(rfbClient* client)
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{
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gnutls_anon_client_credentials anonCred;
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int ret;
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if ((ret = gnutls_anon_allocate_client_credentials(&anonCred)) < 0 ||
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(ret = gnutls_credentials_set(client->tlsSession, GNUTLS_CRD_ANON, anonCred)) < 0)
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{
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FreeTLS(client);
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rfbClientLog("Failed to create anonymous credentials: %s", gnutls_strerror(ret));
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return FALSE;
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}
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rfbClientLog("TLS anonymous credential created.\n");
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return TRUE;
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}
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static rfbBool
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HandshakeTLS(rfbClient* client)
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{
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int timeout = 15;
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int ret;
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while (timeout > 0 && (ret = gnutls_handshake(client->tlsSession)) < 0)
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{
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if (!gnutls_error_is_fatal(ret))
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{
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rfbClientLog("TLS handshake blocking.\n");
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sleep(1);
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timeout--;
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continue;
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}
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rfbClientLog("TLS handshake failed: %s.\n", gnutls_strerror(ret));
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FreeTLS(client);
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return FALSE;
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}
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if (timeout <= 0)
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{
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rfbClientLog("TLS handshake timeout.\n");
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FreeTLS(client);
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return FALSE;
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}
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rfbClientLog("TLS handshake done.\n");
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return TRUE;
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}
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/* VeNCrypt sub auth. 1 byte auth count, followed by count * 4 byte integers */
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static rfbBool
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ReadVeNCryptSecurityType(rfbClient* client, uint32_t *result)
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{
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uint8_t count=0;
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uint8_t loop=0;
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uint8_t flag=0;
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uint32_t tAuth[256], t;
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char buf1[500],buf2[10];
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uint32_t authScheme;
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if (!ReadFromRFBServer(client, (char *)&count, 1)) return FALSE;
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if (count==0)
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{
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rfbClientLog("List of security types is ZERO. Giving up.\n");
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return FALSE;
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}
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if (count>sizeof(tAuth))
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{
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rfbClientLog("%d security types are too many; maximum is %d\n", count, sizeof(tAuth));
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return FALSE;
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}
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rfbClientLog("We have %d security types to read\n", count);
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authScheme=0;
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/* now, we have a list of available security types to read ( uint8_t[] ) */
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for (loop=0;loop<count;loop++)
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{
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if (!ReadFromRFBServer(client, (char *)&tAuth[loop], 4)) return FALSE;
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t=rfbClientSwap32IfLE(tAuth[loop]);
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rfbClientLog("%d) Received security type %d\n", loop, t);
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if (flag) continue;
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if (t==rfbVeNCryptTLSNone ||
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t==rfbVeNCryptTLSVNC ||
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t==rfbVeNCryptTLSPlain ||
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t==rfbVeNCryptX509None ||
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t==rfbVeNCryptX509VNC ||
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t==rfbVeNCryptX509Plain)
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{
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flag++;
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authScheme=t;
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rfbClientLog("Selecting security type %d (%d/%d in the list)\n", authScheme, loop, count);
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/* send back 4 bytes (in original byte order!) indicating which security type to use */
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if (!WriteToRFBServer(client, (char *)&tAuth[loop], 4)) return FALSE;
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}
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tAuth[loop]=t;
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}
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if (authScheme==0)
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{
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memset(buf1, 0, sizeof(buf1));
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for (loop=0;loop<count;loop++)
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{
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if (strlen(buf1)>=sizeof(buf1)-1) break;
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snprintf(buf2, sizeof(buf2), (loop>0 ? ", %d" : "%d"), (int)tAuth[loop]);
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strncat(buf1, buf2, sizeof(buf1)-strlen(buf1)-1);
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}
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rfbClientLog("Unknown VeNCrypt authentication scheme from VNC server: %s\n",
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buf1);
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return FALSE;
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}
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*result = authScheme;
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return TRUE;
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}
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static void
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FreeX509Credential(rfbCredential *cred)
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{
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if (cred->x509Credential.x509CACertFile) free(cred->x509Credential.x509CACertFile);
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if (cred->x509Credential.x509CACrlFile) free(cred->x509Credential.x509CACrlFile);
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if (cred->x509Credential.x509ClientCertFile) free(cred->x509Credential.x509ClientCertFile);
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if (cred->x509Credential.x509ClientKeyFile) free(cred->x509Credential.x509ClientKeyFile);
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free(cred);
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}
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static gnutls_certificate_credentials_t
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CreateX509CertCredential(rfbCredential *cred)
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{
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gnutls_certificate_credentials_t x509_cred;
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int ret;
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if (!cred->x509Credential.x509CACertFile)
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{
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rfbClientLog("No CA certificate provided.\n");
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return NULL;
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}
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if ((ret = gnutls_certificate_allocate_credentials(&x509_cred)) < 0)
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{
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rfbClientLog("Cannot allocate credentials: %s.\n", gnutls_strerror(ret));
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return NULL;
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}
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if ((ret = gnutls_certificate_set_x509_trust_file(x509_cred,
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cred->x509Credential.x509CACertFile, GNUTLS_X509_FMT_PEM)) < 0)
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{
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rfbClientLog("Cannot load CA credentials: %s.\n", gnutls_strerror(ret));
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gnutls_certificate_free_credentials (x509_cred);
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return NULL;
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}
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if (cred->x509Credential.x509ClientCertFile && cred->x509Credential.x509ClientKeyFile)
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{
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if ((ret = gnutls_certificate_set_x509_key_file(x509_cred,
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cred->x509Credential.x509ClientCertFile, cred->x509Credential.x509ClientKeyFile,
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GNUTLS_X509_FMT_PEM)) < 0)
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{
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rfbClientLog("Cannot load client certificate or key: %s.\n", gnutls_strerror(ret));
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gnutls_certificate_free_credentials (x509_cred);
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return NULL;
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}
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} else
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{
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rfbClientLog("No client certificate or key provided.\n");
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}
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if (cred->x509Credential.x509CACrlFile)
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{
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if ((ret = gnutls_certificate_set_x509_crl_file(x509_cred,
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cred->x509Credential.x509CACrlFile, GNUTLS_X509_FMT_PEM)) < 0)
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{
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rfbClientLog("Cannot load CRL: %s.\n", gnutls_strerror(ret));
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gnutls_certificate_free_credentials (x509_cred);
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return NULL;
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}
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} else
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{
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rfbClientLog("No CRL provided.\n");
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}
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gnutls_certificate_set_dh_params (x509_cred, rfbDHParams);
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return x509_cred;
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}
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#endif
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rfbBool
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HandleAnonTLSAuth(rfbClient* client)
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{
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#ifdef LIBVNCSERVER_WITH_CLIENT_TLS
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if (!InitializeTLS() || !InitializeTLSSession(client, TRUE)) return FALSE;
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if (!SetTLSAnonCredential(client)) return FALSE;
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if (!HandshakeTLS(client)) return FALSE;
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return TRUE;
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#else
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rfbClientLog("TLS is not supported.\n");
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return FALSE;
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#endif
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}
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rfbBool
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HandleVeNCryptAuth(rfbClient* client)
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{
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#ifdef LIBVNCSERVER_WITH_CLIENT_TLS
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uint8_t major, minor, status;
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uint32_t authScheme;
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rfbBool anonTLS;
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gnutls_certificate_credentials_t x509_cred = NULL;
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int ret;
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if (!InitializeTLS()) return FALSE;
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/* Read VeNCrypt version */
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if (!ReadFromRFBServer(client, (char *)&major, 1) ||
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!ReadFromRFBServer(client, (char *)&minor, 1))
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{
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return FALSE;
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}
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rfbClientLog("Got VeNCrypt version %d.%d from server.\n", (int)major, (int)minor);
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if (major != 0 && minor != 2)
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{
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rfbClientLog("Unsupported VeNCrypt version.\n");
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return FALSE;
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}
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if (!WriteToRFBServer(client, (char *)&major, 1) ||
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!WriteToRFBServer(client, (char *)&minor, 1) ||
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!ReadFromRFBServer(client, (char *)&status, 1))
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{
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return FALSE;
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}
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if (status != 0)
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{
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rfbClientLog("Server refused VeNCrypt version %d.%d.\n", (int)major, (int)minor);
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return FALSE;
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}
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if (!ReadVeNCryptSecurityType(client, &authScheme)) return FALSE;
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if (!ReadFromRFBServer(client, (char *)&status, 1) || status != 1)
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{
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rfbClientLog("Server refused VeNCrypt authentication %d (%d).\n", authScheme, (int)status);
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return FALSE;
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}
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client->subAuthScheme = authScheme;
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/* Some VeNCrypt security types are anonymous TLS, others are X509 */
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switch (authScheme)
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{
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case rfbVeNCryptTLSNone:
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case rfbVeNCryptTLSVNC:
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case rfbVeNCryptTLSPlain:
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anonTLS = TRUE;
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break;
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default:
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anonTLS = FALSE;
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break;
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}
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/* Get X509 Credentials if it's not anonymous */
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if (!anonTLS)
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{
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rfbCredential *cred;
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if (!client->GetCredential)
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{
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rfbClientLog("GetCredential callback is not set.\n");
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return FALSE;
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}
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cred = client->GetCredential(client, rfbCredentialTypeX509);
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if (!cred)
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{
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rfbClientLog("Reading credential failed\n");
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return FALSE;
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}
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x509_cred = CreateX509CertCredential(cred);
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FreeX509Credential(cred);
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if (!x509_cred) return FALSE;
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}
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/* Start up the TLS session */
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if (!InitializeTLSSession(client, anonTLS)) return FALSE;
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if (anonTLS)
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{
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if (!SetTLSAnonCredential(client)) return FALSE;
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}
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else
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{
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if ((ret = gnutls_credentials_set(client->tlsSession, GNUTLS_CRD_CERTIFICATE, x509_cred)) < 0)
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{
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rfbClientLog("Cannot set x509 credential: %s.\n", gnutls_strerror(ret));
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FreeTLS(client);
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return FALSE;
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}
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}
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if (!HandshakeTLS(client)) return FALSE;
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/* TODO: validate certificate */
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/* We are done here. The caller should continue with client->subAuthScheme
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* to do actual sub authentication.
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*/
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return TRUE;
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#else
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rfbClientLog("TLS is not supported.\n");
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return FALSE;
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#endif
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}
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int
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ReadFromTLS(rfbClient* client, char *out, unsigned int n)
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{
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#ifdef LIBVNCSERVER_WITH_CLIENT_TLS
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ssize_t ret;
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ret = gnutls_record_recv(client->tlsSession, out, n);
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if (ret >= 0) return ret;
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if (ret == GNUTLS_E_REHANDSHAKE || ret == GNUTLS_E_AGAIN)
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{
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errno = EAGAIN;
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} else
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{
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rfbClientLog("Error reading from TLS: %s.\n", gnutls_strerror(ret));
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errno = EINTR;
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}
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return -1;
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#else
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rfbClientLog("TLS is not supported.\n");
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errno = EINTR;
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return -1;
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#endif
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}
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int
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WriteToTLS(rfbClient* client, char *buf, unsigned int n)
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{
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#ifdef LIBVNCSERVER_WITH_CLIENT_TLS
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unsigned int offset = 0;
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ssize_t ret;
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while (offset < n)
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{
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ret = gnutls_record_send(client->tlsSession, buf+offset, (size_t)(n-offset));
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if (ret == 0) continue;
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if (ret < 0)
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{
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if (ret == GNUTLS_E_AGAIN || ret == GNUTLS_E_INTERRUPTED) continue;
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rfbClientLog("Error writing to TLS: %s.\n", gnutls_strerror(ret));
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return -1;
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}
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offset += (unsigned int)ret;
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}
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return offset;
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#else
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rfbClientLog("TLS is not supported.\n");
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errno = EINTR;
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return -1;
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#endif
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}
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void FreeTLS(rfbClient* client)
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{
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#ifdef LIBVNCSERVER_WITH_CLIENT_TLS
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if (client->tlsSession)
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{
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gnutls_deinit(client->tlsSession);
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client->tlsSession = NULL;
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}
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#endif
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}
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