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libtdevnc/libvncclient/tls_openssl.c

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/*
* Copyright (C) 2012 Philip Van Hoof <philip@codeminded.be>
* Copyright (C) 2009 Vic Lee.
*
* This is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this software; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
* USA.
*/
#ifndef _MSC_VER
#define _XOPEN_SOURCE 500
#endif
#include <rfb/rfbclient.h>
#include <errno.h>
#include <openssl/err.h>
#include <openssl/ssl.h>
#include <openssl/x509.h>
#include <openssl/rand.h>
#include <openssl/x509.h>
#ifdef _MSC_VER
typedef CRITICAL_SECTION MUTEX_TYPE;
#define MUTEX_INIT(mutex) InitializeCriticalSection(&mutex)
#define MUTEX_FREE(mutex) DeleteCriticalSection(&mutex)
#define MUTEX_LOCK(mutex) EnterCriticalSection(&mutex)
#define MUTEX_UNLOCK(mutex) LeaveCriticalSection(&mutex)
#define CURRENT_THREAD_ID GetCurrentThreadId()
#else
typedef pthread_mutex_t MUTEX_TYPE;
#define MUTEX_INIT(mutex) {\
pthread_mutexattr_t mutexAttr;\
pthread_mutexattr_init(&mutexAttr);\
pthread_mutexattr_settype(&mutexAttr, PTHREAD_MUTEX_RECURSIVE);\
pthread_mutex_init(&mutex, &mutexAttr);\
}
#define MUTEX_FREE(mutex) pthread_mutex_destroy(&mutex)
#define MUTEX_LOCK(mutex) pthread_mutex_lock(&mutex)
#define MUTEX_UNLOCK(mutex) pthread_mutex_unlock(&mutex)
#define CURRENT_THREAD_ID pthread_self()
#endif
#ifndef _MSC_VER
#include <pthread.h>
#endif
#include "tls.h"
#ifdef _MSC_VER
#include <BaseTsd.h> // That's for SSIZE_T
typedef SSIZE_T ssize_t;
#define snprintf _snprintf
#endif
static rfbBool rfbTLSInitialized = FALSE;
static MUTEX_TYPE *mutex_buf = NULL;
struct CRYPTO_dynlock_value {
MUTEX_TYPE mutex;
};
static void locking_function(int mode, int n, const char *file, int line)
{
if (mode & CRYPTO_LOCK)
MUTEX_LOCK(mutex_buf[n]);
else
MUTEX_UNLOCK(mutex_buf[n]);
}
static unsigned long id_function(void)
{
return ((unsigned long) CURRENT_THREAD_ID);
}
static struct CRYPTO_dynlock_value *dyn_create_function(const char *file, int line)
{
struct CRYPTO_dynlock_value *value;
value = (struct CRYPTO_dynlock_value *)
malloc(sizeof(struct CRYPTO_dynlock_value));
if (!value)
goto err;
MUTEX_INIT(value->mutex);
return value;
err:
return (NULL);
}
static void dyn_lock_function (int mode, struct CRYPTO_dynlock_value *l, const char *file, int line)
{
if (mode & CRYPTO_LOCK)
MUTEX_LOCK(l->mutex);
else
MUTEX_UNLOCK(l->mutex);
}
static void
dyn_destroy_function(struct CRYPTO_dynlock_value *l, const char *file, int line)
{
MUTEX_FREE(l->mutex);
free(l);
}
static int
ssl_errno (SSL *ssl, int ret)
{
switch (SSL_get_error (ssl, ret)) {
case SSL_ERROR_NONE:
return 0;
case SSL_ERROR_ZERO_RETURN:
/* this one does not map well at all */
//d(printf ("ssl_errno: SSL_ERROR_ZERO_RETURN\n"));
return EINVAL;
case SSL_ERROR_WANT_READ: /* non-fatal; retry */
case SSL_ERROR_WANT_WRITE: /* non-fatal; retry */
//d(printf ("ssl_errno: SSL_ERROR_WANT_[READ,WRITE]\n"));
return EAGAIN;
case SSL_ERROR_SYSCALL:
//d(printf ("ssl_errno: SSL_ERROR_SYSCALL\n"));
return EINTR;
case SSL_ERROR_SSL:
//d(printf ("ssl_errno: SSL_ERROR_SSL <-- very useful error...riiiiight\n"));
return EINTR;
default:
//d(printf ("ssl_errno: default error\n"));
return EINTR;
}
}
static rfbBool
InitializeTLS(void)
{
int i;
if (rfbTLSInitialized) return TRUE;
mutex_buf = malloc(CRYPTO_num_locks() * sizeof(MUTEX_TYPE));
if (mutex_buf == NULL) {
rfbClientLog("Failed to initialized OpenSSL: memory.\n");
return (-1);
}
for (i = 0; i < CRYPTO_num_locks(); i++)
MUTEX_INIT(mutex_buf[i]);
CRYPTO_set_locking_callback(locking_function);
CRYPTO_set_id_callback(id_function);
CRYPTO_set_dynlock_create_callback(dyn_create_function);
CRYPTO_set_dynlock_lock_callback(dyn_lock_function);
CRYPTO_set_dynlock_destroy_callback(dyn_destroy_function);
SSL_load_error_strings();
SSLeay_add_ssl_algorithms();
RAND_load_file("/dev/urandom", 1024);
rfbClientLog("OpenSSL version %s initialized.\n", SSLeay_version(SSLEAY_VERSION));
rfbTLSInitialized = TRUE;
return TRUE;
}
static int sock_read_ready(SSL *ssl, uint32_t ms)
{
int r = 0;
fd_set fds;
struct timeval tv;
FD_ZERO(&fds);
FD_SET(SSL_get_fd(ssl), &fds);
tv.tv_sec = ms / 1000;
tv.tv_usec = (ms % 1000) * 1000;
r = select (SSL_get_fd(ssl) + 1, &fds, NULL, NULL, &tv);
return r;
}
static int wait_for_data(SSL *ssl, int ret, int timeout)
{
int err;
int retval = 1;
err = SSL_get_error(ssl, ret);
switch(err)
{
case SSL_ERROR_WANT_READ:
case SSL_ERROR_WANT_WRITE:
ret = sock_read_ready(ssl, timeout*1000);
if (ret == -1) {
retval = 2;
}
break;
default:
retval = 3;
long verify_res = SSL_get_verify_result(ssl);
if (verify_res != X509_V_OK)
rfbClientLog("Could not verify server certificate: %s.\n",
X509_verify_cert_error_string(verify_res));
break;
}
ERR_clear_error();
return retval;
}
static rfbBool
load_crls_from_file(char *file, SSL_CTX *ssl_ctx)
{
X509_STORE *st;
X509_CRL *crl;
int i;
int count = 0;
BIO *bio;
STACK_OF(X509_INFO) *xis = NULL;
X509_INFO *xi;
st = SSL_CTX_get_cert_store(ssl_ctx);
int rv = 0;
bio = BIO_new_file(file, "r");
if (bio == NULL)
return FALSE;
xis = PEM_X509_INFO_read_bio(bio, NULL, NULL, NULL);
BIO_free(bio);
for (i = 0; i < sk_X509_INFO_num(xis); i++)
{
xi = sk_X509_INFO_value(xis, i);
if (xi->crl)
{
X509_STORE_add_crl(st, xi->crl);
xi->crl = NULL;
count++;
}
}
sk_X509_INFO_pop_free(xis, X509_INFO_free);
if (count > 0)
return TRUE;
else
return FALSE;
}
static SSL *
open_ssl_connection (rfbClient *client, int sockfd, rfbBool anonTLS, rfbCredential *cred)
{
SSL_CTX *ssl_ctx = NULL;
SSL *ssl = NULL;
int n, finished = 0;
X509_VERIFY_PARAM *param;
uint8_t verify_crls = cred->x509Credential.x509CrlVerifyMode;
if (!(ssl_ctx = SSL_CTX_new(SSLv23_client_method())))
{
rfbClientLog("Could not create new SSL context.\n");
return NULL;
}
param = X509_VERIFY_PARAM_new();
/* Setup verification if not anonymous */
if (!anonTLS)
{
if (cred->x509Credential.x509CACertFile)
{
if (!SSL_CTX_load_verify_locations(ssl_ctx, cred->x509Credential.x509CACertFile, NULL))
{
rfbClientLog("Failed to load CA certificate from %s.\n",
cred->x509Credential.x509CACertFile);
goto error_free_ctx;
}
} else {
rfbClientLog("Using default paths for certificate verification.\n");
SSL_CTX_set_default_verify_paths (ssl_ctx);
}
if (cred->x509Credential.x509CACrlFile)
{
if (!load_crls_from_file(cred->x509Credential.x509CACrlFile, ssl_ctx))
{
rfbClientLog("CRLs could not be loaded.\n");
goto error_free_ctx;
}
if (verify_crls == rfbX509CrlVerifyNone) verify_crls = rfbX509CrlVerifyAll;
}
if (cred->x509Credential.x509ClientCertFile && cred->x509Credential.x509ClientKeyFile)
{
if (SSL_CTX_use_certificate_chain_file(ssl_ctx, cred->x509Credential.x509ClientCertFile) != 1)
{
rfbClientLog("Client certificate could not be loaded.\n");
goto error_free_ctx;
}
if (SSL_CTX_use_PrivateKey_file(ssl_ctx, cred->x509Credential.x509ClientKeyFile,
SSL_FILETYPE_PEM) != 1)
{
rfbClientLog("Client private key could not be loaded.\n");
goto error_free_ctx;
}
if (SSL_CTX_check_private_key(ssl_ctx) == 0) {
rfbClientLog("Client certificate and private key do not match.\n");
goto error_free_ctx;
}
}
SSL_CTX_set_verify(ssl_ctx, SSL_VERIFY_PEER, NULL);
if (verify_crls == rfbX509CrlVerifyClient)
X509_VERIFY_PARAM_set_flags(param, X509_V_FLAG_CRL_CHECK);
else if (verify_crls == rfbX509CrlVerifyAll)
X509_VERIFY_PARAM_set_flags(param, X509_V_FLAG_CRL_CHECK | X509_V_FLAG_CRL_CHECK_ALL);
if(!X509_VERIFY_PARAM_set1_host(param, client->serverHost, strlen(client->serverHost)))
{
rfbClientLog("Could not set server name for verification.\n");
goto error_free_ctx;
}
SSL_CTX_set1_param(ssl_ctx, param);
}
if (!(ssl = SSL_new (ssl_ctx)))
{
rfbClientLog("Could not create a new SSL session.\n");
goto error_free_ctx;
}
/* TODO: finetune this list, take into account anonTLS bool */
SSL_set_cipher_list(ssl, "ALL");
SSL_set_fd (ssl, sockfd);
SSL_CTX_set_app_data (ssl_ctx, client);
do
{
n = SSL_connect(ssl);
if (n != 1)
{
if (wait_for_data(ssl, n, 1) != 1)
{
finished = 1;
SSL_shutdown(ssl);
goto error_free_ssl;
}
}
} while( n != 1 && finished != 1 );
X509_VERIFY_PARAM_free(param);
return ssl;
error_free_ssl:
SSL_free(ssl);
error_free_ctx:
X509_VERIFY_PARAM_free(param);
SSL_CTX_free(ssl_ctx);
return NULL;
}
static rfbBool
InitializeTLSSession(rfbClient* client, rfbBool anonTLS, rfbCredential *cred)
{
if (client->tlsSession) return TRUE;
client->tlsSession = open_ssl_connection (client, client->sock, anonTLS, cred);
if (!client->tlsSession)
return FALSE;
rfbClientLog("TLS session initialized.\n");
return TRUE;
}
static rfbBool
HandshakeTLS(rfbClient* client)
{
int timeout = 15;
int ret;
return TRUE;
while (timeout > 0 && (ret = SSL_do_handshake(client->tlsSession)) < 0)
{
if (ret != -1)
{
rfbClientLog("TLS handshake blocking.\n");
#ifdef WIN32
Sleep(1000);
#else
sleep(1);
#endif
timeout--;
continue;
}
rfbClientLog("TLS handshake failed.\n");
FreeTLS(client);
return FALSE;
}
if (timeout <= 0)
{
rfbClientLog("TLS handshake timeout.\n");
FreeTLS(client);
return FALSE;
}
rfbClientLog("TLS handshake done.\n");
return TRUE;
}
/* VeNCrypt sub auth. 1 byte auth count, followed by count * 4 byte integers */
static rfbBool
ReadVeNCryptSecurityType(rfbClient* client, uint32_t *result)
{
uint8_t count=0;
uint8_t loop=0;
uint8_t flag=0;
uint32_t tAuth[256], t;
char buf1[500],buf2[10];
uint32_t authScheme;
if (!ReadFromRFBServer(client, (char *)&count, 1)) return FALSE;
if (count==0)
{
rfbClientLog("List of security types is ZERO. Giving up.\n");
return FALSE;
}
if (count>sizeof(tAuth))
{
rfbClientLog("%d security types are too many; maximum is %d\n", count, sizeof(tAuth));
return FALSE;
}
rfbClientLog("We have %d security types to read\n", count);
authScheme=0;
/* now, we have a list of available security types to read ( uint8_t[] ) */
for (loop=0;loop<count;loop++)
{
if (!ReadFromRFBServer(client, (char *)&tAuth[loop], 4)) return FALSE;
t=rfbClientSwap32IfLE(tAuth[loop]);
rfbClientLog("%d) Received security type %d\n", loop, t);
if (flag) continue;
if (t==rfbVeNCryptTLSNone ||
t==rfbVeNCryptTLSVNC ||
t==rfbVeNCryptTLSPlain ||
#ifdef LIBVNCSERVER_HAVE_SASL
t==rfbVeNCryptTLSSASL ||
t==rfbVeNCryptX509SASL ||
#endif /*LIBVNCSERVER_HAVE_SASL */
t==rfbVeNCryptX509None ||
t==rfbVeNCryptX509VNC ||
t==rfbVeNCryptX509Plain)
{
flag++;
authScheme=t;
rfbClientLog("Selecting security type %d (%d/%d in the list)\n", authScheme, loop, count);
/* send back 4 bytes (in original byte order!) indicating which security type to use */
if (!WriteToRFBServer(client, (char *)&tAuth[loop], 4)) return FALSE;
}
tAuth[loop]=t;
}
if (authScheme==0)
{
memset(buf1, 0, sizeof(buf1));
for (loop=0;loop<count;loop++)
{
if (strlen(buf1)>=sizeof(buf1)-1) break;
snprintf(buf2, sizeof(buf2), (loop>0 ? ", %d" : "%d"), (int)tAuth[loop]);
strncat(buf1, buf2, sizeof(buf1)-strlen(buf1)-1);
}
rfbClientLog("Unknown VeNCrypt authentication scheme from VNC server: %s\n",
buf1);
return FALSE;
}
*result = authScheme;
return TRUE;
}
rfbBool
HandleAnonTLSAuth(rfbClient* client)
{
if (!InitializeTLS() || !InitializeTLSSession(client, TRUE, NULL)) return FALSE;
if (!HandshakeTLS(client)) return FALSE;
return TRUE;
}
static void
FreeX509Credential(rfbCredential *cred)
{
if (cred->x509Credential.x509CACertFile) free(cred->x509Credential.x509CACertFile);
if (cred->x509Credential.x509CACrlFile) free(cred->x509Credential.x509CACrlFile);
if (cred->x509Credential.x509ClientCertFile) free(cred->x509Credential.x509ClientCertFile);
if (cred->x509Credential.x509ClientKeyFile) free(cred->x509Credential.x509ClientKeyFile);
free(cred);
}
rfbBool
HandleVeNCryptAuth(rfbClient* client)
{
uint8_t major, minor, status;
uint32_t authScheme;
rfbBool anonTLS;
rfbCredential *cred = NULL;
rfbBool result = TRUE;
if (!InitializeTLS()) return FALSE;
/* Read VeNCrypt version */
if (!ReadFromRFBServer(client, (char *)&major, 1) ||
!ReadFromRFBServer(client, (char *)&minor, 1))
{
return FALSE;
}
rfbClientLog("Got VeNCrypt version %d.%d from server.\n", (int)major, (int)minor);
if (major != 0 && minor != 2)
{
rfbClientLog("Unsupported VeNCrypt version.\n");
return FALSE;
}
if (!WriteToRFBServer(client, (char *)&major, 1) ||
!WriteToRFBServer(client, (char *)&minor, 1) ||
!ReadFromRFBServer(client, (char *)&status, 1))
{
return FALSE;
}
if (status != 0)
{
rfbClientLog("Server refused VeNCrypt version %d.%d.\n", (int)major, (int)minor);
return FALSE;
}
if (!ReadVeNCryptSecurityType(client, &authScheme)) return FALSE;
if (!ReadFromRFBServer(client, (char *)&status, 1) || status != 1)
{
rfbClientLog("Server refused VeNCrypt authentication %d (%d).\n", authScheme, (int)status);
return FALSE;
}
client->subAuthScheme = authScheme;
/* Some VeNCrypt security types are anonymous TLS, others are X509 */
switch (authScheme)
{
case rfbVeNCryptTLSNone:
case rfbVeNCryptTLSVNC:
case rfbVeNCryptTLSPlain:
#ifdef LIBVNCSERVER_HAVE_SASL
case rfbVeNCryptTLSSASL:
#endif /* LIBVNCSERVER_HAVE_SASL */
anonTLS = TRUE;
break;
default:
anonTLS = FALSE;
break;
}
/* Get X509 Credentials if it's not anonymous */
if (!anonTLS)
{
if (!client->GetCredential)
{
rfbClientLog("GetCredential callback is not set.\n");
return FALSE;
}
cred = client->GetCredential(client, rfbCredentialTypeX509);
if (!cred)
{
rfbClientLog("Reading credential failed\n");
return FALSE;
}
}
/* Start up the TLS session */
if (!InitializeTLSSession(client, anonTLS, cred)) result = FALSE;
if (!HandshakeTLS(client)) result = FALSE;
/* We are done here. The caller should continue with client->subAuthScheme
* to do actual sub authentication.
*/
if (cred) FreeX509Credential(cred);
return result;
}
int
ReadFromTLS(rfbClient* client, char *out, unsigned int n)
{
ssize_t ret;
ret = SSL_read (client->tlsSession, out, n);
if (ret >= 0)
return ret;
else {
errno = ssl_errno (client->tlsSession, ret);
if (errno != EAGAIN) {
rfbClientLog("Error reading from TLS: -.\n");
}
}
return -1;
}
int
WriteToTLS(rfbClient* client, const char *buf, unsigned int n)
{
unsigned int offset = 0;
ssize_t ret;
while (offset < n)
{
ret = SSL_write (client->tlsSession, buf + offset, (size_t)(n-offset));
if (ret < 0)
errno = ssl_errno (client->tlsSession, ret);
if (ret == 0) continue;
if (ret < 0)
{
if (errno == EAGAIN || errno == EWOULDBLOCK) continue;
rfbClientLog("Error writing to TLS: -\n");
return -1;
}
offset += (unsigned int)ret;
}
return offset;
}
void FreeTLS(rfbClient* client)
{
int i;
if (mutex_buf != NULL) {
CRYPTO_set_dynlock_create_callback(NULL);
CRYPTO_set_dynlock_lock_callback(NULL);
CRYPTO_set_dynlock_destroy_callback(NULL);
CRYPTO_set_locking_callback(NULL);
CRYPTO_set_id_callback(NULL);
for (i = 0; i < CRYPTO_num_locks(); i++)
MUTEX_FREE(mutex_buf[i]);
free(mutex_buf);
mutex_buf = NULL;
}
SSL_free(client->tlsSession);
}
#ifdef LIBVNCSERVER_HAVE_SASL
int GetTLSCipherBits(rfbClient* client)
{
SSL *ssl = (SSL *)(client->tlsSession);
const SSL_CIPHER *cipher = SSL_get_current_cipher(ssl);
return SSL_CIPHER_get_bits(cipher, NULL);
}
#endif /* LIBVNCSERVER_HAVE_SASL */
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