FreeRDP/libfreerdp/crypto/tls.c

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2011-07-04 01:29:09 +04:00
/**
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* FreeRDP: A Remote Desktop Protocol Implementation
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* Transport Layer Security
*
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* Copyright 2011-2012 Marc-Andre Moreau <marcandre.moreau@gmail.com>
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*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
2011-08-29 00:46:36 +04:00
* http://www.apache.org/licenses/LICENSE-2.0
2011-07-04 01:29:09 +04:00
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <assert.h>
#include <winpr/crt.h>
#include <winpr/sspi.h>
OpenSSL thread safety freerdp/winpr had the following issues: * The non reentrant SSL_library_init() was called concurrently (crash) * Missing code/api to set the eventually required OpenSSL static and dynamic locking callbacks * Missing code/api to free the application-global or thread-local OpenSSL data and tables This commit creates two new winpr functions: BOOL winpr_InitializeSSL(DWORD flags): Use the flag WINPR_SSL_INIT_ALREADY_INITIALIZED if you want to tell winpr that your application has already initialized OpenSSL. If required use the flag WINPR_SSL_INIT_ENABLE_LOCKING to tell winpr that it should set the OpenSSL static and dynamic locking callbacks. Otherwise just call it with the flag WINPR_SSL_INIT_DEFAULT. The recommended way is that your application calls this function once before any threads are created. However, in order to support lazy OpenSSL library initialization winpr_InitializeSSL() can also safely be called multiple times and concurrently because it uses the new InitOnceExecuteOnce() function to guarantee that the initialization is only performed successfully once during the life time of the calling process. BOOL winpr_CleanupSSL(DWORD flags): If you create a thread that uses SSL you should call this function before the thread returns using the flag WINPR_SSL_CLEANUP_THREAD in order to clean up the thread-local OpenSSL data and tables. Call the function with the flag WINPR_SSL_CLEANUP_GLOBAL before terminating your application. Note: This commit only replaced the current occurences of the SSL_load_error_strings(); SSL_library_init(); pairs in the freerdp source with winpr_InitializeSSL(). None of the server or client applications has been changed according to the recommended usage described above (TBDL).
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#include <winpr/ssl.h>
#include <winpr/stream.h>
#include <freerdp/utils/tcp.h>
#include <freerdp/utils/ringbuffer.h>
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#include <freerdp/log.h>
#include <freerdp/crypto/tls.h>
#include "../core/tcp.h"
#ifdef HAVE_POLL_H
#include <poll.h>
#endif
#define TAG FREERDP_TAG("crypto")
struct _BIO_RDP_TLS
{
SSL* ssl;
};
typedef struct _BIO_RDP_TLS BIO_RDP_TLS;
long bio_rdp_tls_callback(BIO* bio, int mode, const char* argp, int argi, long argl, long ret)
{
return 1;
}
static int bio_rdp_tls_write(BIO* bio, const char* buf, int size)
{
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int error;
int status;
BIO_RDP_TLS* tls = (BIO_RDP_TLS*) bio->ptr;
if (!buf || !tls)
return 0;
BIO_clear_flags(bio, BIO_FLAGS_WRITE | BIO_FLAGS_READ | BIO_FLAGS_IO_SPECIAL);
status = SSL_write(tls->ssl, buf, size);
if (status <= 0)
{
switch (SSL_get_error(tls->ssl, status))
{
case SSL_ERROR_NONE:
BIO_clear_flags(bio, BIO_FLAGS_SHOULD_RETRY);
break;
case SSL_ERROR_WANT_WRITE:
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BIO_set_flags(bio, BIO_FLAGS_WRITE | BIO_FLAGS_SHOULD_RETRY);
break;
case SSL_ERROR_WANT_READ:
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BIO_set_flags(bio, BIO_FLAGS_READ | BIO_FLAGS_SHOULD_RETRY);
break;
case SSL_ERROR_WANT_X509_LOOKUP:
BIO_set_flags(bio, BIO_FLAGS_IO_SPECIAL);
bio->retry_reason = BIO_RR_SSL_X509_LOOKUP;
break;
case SSL_ERROR_WANT_CONNECT:
BIO_set_flags(bio, BIO_FLAGS_IO_SPECIAL);
bio->retry_reason = BIO_RR_CONNECT;
break;
case SSL_ERROR_SYSCALL:
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error = WSAGetLastError();
if ((error == WSAEWOULDBLOCK) || (error == WSAEINTR) ||
(error == WSAEINPROGRESS) || (error == WSAEALREADY))
{
BIO_set_flags(bio, (BIO_FLAGS_WRITE | BIO_FLAGS_SHOULD_RETRY));
}
else
{
BIO_clear_flags(bio, BIO_FLAGS_SHOULD_RETRY);
}
break;
case SSL_ERROR_SSL:
BIO_clear_flags(bio, BIO_FLAGS_SHOULD_RETRY);
break;
}
}
return status;
}
static int bio_rdp_tls_read(BIO* bio, char* buf, int size)
{
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int error;
int status;
BIO_RDP_TLS* tls = (BIO_RDP_TLS*) bio->ptr;
if (!buf || !tls)
return 0;
BIO_clear_flags(bio, BIO_FLAGS_WRITE | BIO_FLAGS_READ | BIO_FLAGS_IO_SPECIAL);
status = SSL_read(tls->ssl, buf, size);
if (status <= 0)
{
switch (SSL_get_error(tls->ssl, status))
{
case SSL_ERROR_NONE:
BIO_clear_flags(bio, BIO_FLAGS_SHOULD_RETRY);
break;
case SSL_ERROR_WANT_READ:
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BIO_set_flags(bio, BIO_FLAGS_READ | BIO_FLAGS_SHOULD_RETRY);
break;
case SSL_ERROR_WANT_WRITE:
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BIO_set_flags(bio, BIO_FLAGS_WRITE | BIO_FLAGS_SHOULD_RETRY);
break;
case SSL_ERROR_WANT_X509_LOOKUP:
BIO_set_flags(bio, BIO_FLAGS_IO_SPECIAL);
bio->retry_reason = BIO_RR_SSL_X509_LOOKUP;
break;
case SSL_ERROR_WANT_ACCEPT:
BIO_set_flags(bio, BIO_FLAGS_IO_SPECIAL);
bio->retry_reason = BIO_RR_ACCEPT;
break;
case SSL_ERROR_WANT_CONNECT:
BIO_set_flags(bio, BIO_FLAGS_IO_SPECIAL);
bio->retry_reason = BIO_RR_CONNECT;
break;
case SSL_ERROR_SSL:
BIO_clear_flags(bio, BIO_FLAGS_SHOULD_RETRY);
break;
case SSL_ERROR_ZERO_RETURN:
BIO_clear_flags(bio, BIO_FLAGS_SHOULD_RETRY);
break;
case SSL_ERROR_SYSCALL:
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error = WSAGetLastError();
if ((error == WSAEWOULDBLOCK) || (error == WSAEINTR) ||
(error == WSAEINPROGRESS) || (error == WSAEALREADY) ||
(error == 0))
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{
BIO_set_flags(bio, (BIO_FLAGS_READ | BIO_FLAGS_SHOULD_RETRY));
}
else
{
BIO_clear_flags(bio, BIO_FLAGS_SHOULD_RETRY);
}
break;
}
}
return status;
}
static int bio_rdp_tls_puts(BIO* bio, const char* str)
{
int size;
int status;
if (!str)
return 0;
size = strlen(str);
status = BIO_write(bio, str, size);
return status;
}
static int bio_rdp_tls_gets(BIO* bio, char* str, int size)
{
return 1;
}
static long bio_rdp_tls_ctrl(BIO* bio, int cmd, long num, void* ptr)
{
BIO* rbio;
int status = -1;
BIO_RDP_TLS* tls = (BIO_RDP_TLS*) bio->ptr;
if (!tls)
return 0;
if (!tls->ssl && (cmd != BIO_C_SET_SSL))
return 0;
switch (cmd)
{
case BIO_CTRL_RESET:
SSL_shutdown(tls->ssl);
if (tls->ssl->handshake_func == tls->ssl->method->ssl_connect)
SSL_set_connect_state(tls->ssl);
else if (tls->ssl->handshake_func == tls->ssl->method->ssl_accept)
SSL_set_accept_state(tls->ssl);
SSL_clear(tls->ssl);
if (bio->next_bio)
status = BIO_ctrl(bio->next_bio, cmd, num, ptr);
else if (tls->ssl->rbio)
status = BIO_ctrl(tls->ssl->rbio, cmd, num, ptr);
else
status = 1;
break;
case BIO_C_GET_FD:
status = BIO_ctrl(tls->ssl->rbio, cmd, num, ptr);
break;
case BIO_CTRL_INFO:
status = 0;
break;
case BIO_CTRL_SET_CALLBACK:
status = 0;
break;
case BIO_CTRL_GET_CALLBACK:
*((ULONG_PTR*) ptr) = (ULONG_PTR) SSL_get_info_callback(tls->ssl);
status = 1;
break;
case BIO_C_SSL_MODE:
if (num)
SSL_set_connect_state(tls->ssl);
else
SSL_set_accept_state(tls->ssl);
status = 1;
break;
case BIO_CTRL_GET_CLOSE:
status = bio->shutdown;
break;
case BIO_CTRL_SET_CLOSE:
bio->shutdown = (int) num;
status = 1;
break;
case BIO_CTRL_WPENDING:
status = BIO_ctrl(tls->ssl->wbio, cmd, num, ptr);
break;
case BIO_CTRL_PENDING:
status = SSL_pending(tls->ssl);
if (status == 0)
status = BIO_pending(tls->ssl->rbio);
break;
case BIO_CTRL_FLUSH:
BIO_clear_retry_flags(bio);
status = BIO_ctrl(tls->ssl->wbio, cmd, num, ptr);
BIO_copy_next_retry(bio);
status = 1;
break;
case BIO_CTRL_PUSH:
if (bio->next_bio && (bio->next_bio != tls->ssl->rbio))
{
SSL_set_bio(tls->ssl, bio->next_bio, bio->next_bio);
CRYPTO_add(&(bio->next_bio->references), 1, CRYPTO_LOCK_BIO);
}
status = 1;
break;
case BIO_CTRL_POP:
if (bio == ptr)
{
if (tls->ssl->rbio != tls->ssl->wbio)
BIO_free_all(tls->ssl->wbio);
if (bio->next_bio)
CRYPTO_add(&(bio->next_bio->references), -1, CRYPTO_LOCK_BIO);
tls->ssl->wbio = tls->ssl->rbio = NULL;
}
status = 1;
break;
case BIO_C_GET_SSL:
if (ptr)
{
*((SSL**) ptr) = tls->ssl;
status = 1;
}
break;
case BIO_C_SET_SSL:
bio->shutdown = (int) num;
if (ptr)
tls->ssl = (SSL*) ptr;
rbio = SSL_get_rbio(tls->ssl);
if (rbio)
{
if (bio->next_bio)
BIO_push(rbio, bio->next_bio);
bio->next_bio = rbio;
CRYPTO_add(&(rbio->references), 1, CRYPTO_LOCK_BIO);
}
bio->init = 1;
status = 1;
break;
case BIO_C_DO_STATE_MACHINE:
BIO_clear_flags(bio, BIO_FLAGS_READ | BIO_FLAGS_WRITE | BIO_FLAGS_IO_SPECIAL);
bio->retry_reason = 0;
status = SSL_do_handshake(tls->ssl);
if (status <= 0)
{
switch (SSL_get_error(tls->ssl, status))
{
case SSL_ERROR_WANT_READ:
BIO_set_flags(bio, BIO_FLAGS_READ | BIO_FLAGS_SHOULD_RETRY);
break;
case SSL_ERROR_WANT_WRITE:
BIO_set_flags(bio, BIO_FLAGS_WRITE | BIO_FLAGS_SHOULD_RETRY);
break;
case SSL_ERROR_WANT_CONNECT:
BIO_set_flags(bio, BIO_FLAGS_IO_SPECIAL | BIO_FLAGS_SHOULD_RETRY);
bio->retry_reason = bio->next_bio->retry_reason;
break;
default:
BIO_clear_flags(bio, BIO_FLAGS_SHOULD_RETRY);
break;
}
}
break;
default:
status = BIO_ctrl(tls->ssl->rbio, cmd, num, ptr);
break;
}
return status;
}
static int bio_rdp_tls_new(BIO* bio)
{
BIO_RDP_TLS* tls;
bio->init = 0;
bio->num = 0;
bio->flags = BIO_FLAGS_SHOULD_RETRY;
bio->next_bio = NULL;
tls = calloc(1, sizeof(BIO_RDP_TLS));
if (!tls)
return 0;
bio->ptr = (void*) tls;
return 1;
}
static int bio_rdp_tls_free(BIO* bio)
{
BIO_RDP_TLS* tls;
if (!bio)
return 0;
tls = (BIO_RDP_TLS*) bio->ptr;
if (!tls)
return 0;
if (bio->shutdown)
{
if (bio->init && tls->ssl)
{
SSL_shutdown(tls->ssl);
SSL_free(tls->ssl);
}
bio->init = 0;
bio->flags = 0;
}
free(tls);
return 1;
}
static long bio_rdp_tls_callback_ctrl(BIO* bio, int cmd, bio_info_cb* fp)
{
int status = 0;
BIO_RDP_TLS* tls;
if (!bio)
return 0;
tls = (BIO_RDP_TLS*) bio->ptr;
if (!tls)
return 0;
switch (cmd)
{
case BIO_CTRL_SET_CALLBACK:
SSL_set_info_callback(tls->ssl, (void (*)(const SSL *, int, int)) fp);
status = 1;
break;
default:
status = BIO_callback_ctrl(tls->ssl->rbio, cmd, fp);
break;
}
return status;
}
#define BIO_TYPE_RDP_TLS 68
static BIO_METHOD bio_rdp_tls_methods =
{
BIO_TYPE_RDP_TLS,
"RdpTls",
bio_rdp_tls_write,
bio_rdp_tls_read,
bio_rdp_tls_puts,
bio_rdp_tls_gets,
bio_rdp_tls_ctrl,
bio_rdp_tls_new,
bio_rdp_tls_free,
bio_rdp_tls_callback_ctrl,
};
BIO_METHOD* BIO_s_rdp_tls(void)
{
return &bio_rdp_tls_methods;
}
BIO* BIO_new_rdp_tls(SSL_CTX* ctx, int client)
{
BIO* bio;
SSL* ssl;
bio = BIO_new(BIO_s_rdp_tls());
if (!bio)
return NULL;
ssl = SSL_new(ctx);
if (!ssl)
{
BIO_free(bio);
return NULL;
}
if (client)
SSL_set_connect_state(ssl);
else
SSL_set_accept_state(ssl);
BIO_set_ssl(bio, ssl, BIO_CLOSE);
return bio;
}
static CryptoCert tls_get_certificate(rdpTls* tls, BOOL peer)
{
CryptoCert cert;
X509* remote_cert;
if (peer)
remote_cert = SSL_get_peer_certificate(tls->ssl);
else
remote_cert = X509_dup( SSL_get_certificate(tls->ssl) );
if (!remote_cert)
{
WLog_ERR(TAG, "failed to get the server TLS certificate");
return NULL;
}
cert = malloc(sizeof(*cert));
if (!cert)
{
X509_free(remote_cert);
return NULL;
}
cert->px509 = remote_cert;
return cert;
}
static void tls_free_certificate(CryptoCert cert)
{
X509_free(cert->px509);
free(cert);
}
#define TLS_SERVER_END_POINT "tls-server-end-point:"
SecPkgContext_Bindings* tls_get_channel_bindings(X509* cert)
{
int PrefixLength;
BYTE CertificateHash[32];
UINT32 CertificateHashLength;
BYTE* ChannelBindingToken;
UINT32 ChannelBindingTokenLength;
SEC_CHANNEL_BINDINGS* ChannelBindings;
SecPkgContext_Bindings* ContextBindings;
ZeroMemory(CertificateHash, sizeof(CertificateHash));
X509_digest(cert, EVP_sha256(), CertificateHash, &CertificateHashLength);
PrefixLength = strlen(TLS_SERVER_END_POINT);
ChannelBindingTokenLength = PrefixLength + CertificateHashLength;
ContextBindings = (SecPkgContext_Bindings*) calloc(1, sizeof(SecPkgContext_Bindings));
if (!ContextBindings)
return NULL;
ContextBindings->BindingsLength = sizeof(SEC_CHANNEL_BINDINGS) + ChannelBindingTokenLength;
ChannelBindings = (SEC_CHANNEL_BINDINGS*) calloc(1, ContextBindings->BindingsLength);
if (!ChannelBindings)
goto out_free;
ContextBindings->Bindings = ChannelBindings;
ChannelBindings->cbApplicationDataLength = ChannelBindingTokenLength;
ChannelBindings->dwApplicationDataOffset = sizeof(SEC_CHANNEL_BINDINGS);
ChannelBindingToken = &((BYTE*) ChannelBindings)[ChannelBindings->dwApplicationDataOffset];
strcpy((char*) ChannelBindingToken, TLS_SERVER_END_POINT);
CopyMemory(&ChannelBindingToken[PrefixLength], CertificateHash, CertificateHashLength);
return ContextBindings;
out_free:
free(ContextBindings);
return NULL;
}
#if defined(__APPLE__)
BOOL tls_prepare(rdpTls* tls, BIO *underlying, SSL_METHOD *method, int options, BOOL clientMode)
#else
BOOL tls_prepare(rdpTls* tls, BIO *underlying, const SSL_METHOD *method, int options, BOOL clientMode)
#endif
{
tls->ctx = SSL_CTX_new(method);
if (!tls->ctx)
{
WLog_ERR(TAG, "SSL_CTX_new failed");
return FALSE;
}
SSL_CTX_set_mode(tls->ctx, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER | SSL_MODE_ENABLE_PARTIAL_WRITE);
SSL_CTX_set_options(tls->ctx, options);
SSL_CTX_set_read_ahead(tls->ctx, 1);
if (tls->settings->PermittedTLSCiphers) {
if(!SSL_CTX_set_cipher_list(tls->ctx, tls->settings->PermittedTLSCiphers)) {
WLog_ERR(TAG, "SSL_CTX_set_cipher_list %s failed", tls->settings->PermittedTLSCiphers);
return FALSE;
}
}
tls->bio = BIO_new_rdp_tls(tls->ctx, clientMode);
if (BIO_get_ssl(tls->bio, &tls->ssl) < 0)
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{
WLog_ERR(TAG, "unable to retrieve the SSL of the connection");
return FALSE;
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}
BIO_push(tls->bio, underlying);
return TRUE;
}
int tls_do_handshake(rdpTls* tls, BOOL clientMode)
{
CryptoCert cert;
int verify_status, status;
do
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{
#ifdef HAVE_POLL_H
struct pollfd pollfds;
#else
struct timeval tv;
fd_set rset;
#endif
int fd;
status = BIO_do_handshake(tls->bio);
if (status == 1)
break;
if (!BIO_should_retry(tls->bio))
return -1;
/* we select() only for read even if we should test both read and write
* depending of what have blocked */
fd = BIO_get_fd(tls->bio, NULL);
if (fd < 0)
{
WLog_ERR(TAG, "unable to retrieve BIO fd");
return -1;
}
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#ifdef HAVE_POLL_H
pollfds.fd = fd;
pollfds.events = POLLIN;
pollfds.revents = 0;
do
{
status = poll(&pollfds, 1, 10 * 1000);
}
while ((status < 0) && (errno == EINTR));
#else
FD_ZERO(&rset);
FD_SET(fd, &rset);
tv.tv_sec = 0;
tv.tv_usec = 10 * 1000; /* 10ms */
status = _select(fd + 1, &rset, NULL, NULL, &tv);
#endif
if (status < 0)
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{
WLog_ERR(TAG, "error during select()");
return -1;
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}
}
while (TRUE);
cert = tls_get_certificate(tls, clientMode);
if (!cert)
{
WLog_ERR(TAG, "tls_get_certificate failed to return the server certificate.");
return -1;
}
tls->Bindings = tls_get_channel_bindings(cert->px509);
if (!tls->Bindings)
{
WLog_ERR(TAG, "unable to retrieve bindings");
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verify_status = -1;
goto out;
}
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if (!crypto_cert_get_public_key(cert, &tls->PublicKey, &tls->PublicKeyLength))
{
WLog_ERR(TAG, "crypto_cert_get_public_key failed to return the server public key.");
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verify_status = -1;
goto out;
}
/* Note: server-side NLA needs public keys (keys from us, the server) but no
* certificate verify
*/
verify_status = 1;
if (clientMode)
{
verify_status = tls_verify_certificate(tls, cert, tls->hostname, tls->port);
if (verify_status < 1)
{
WLog_ERR(TAG, "certificate not trusted, aborting.");
tls_disconnect(tls);
verify_status = 0;
}
}
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out:
tls_free_certificate(cert);
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return verify_status;
}
int tls_connect(rdpTls* tls, BIO *underlying)
{
int options = 0;
/**
* SSL_OP_NO_COMPRESSION:
*
* The Microsoft RDP server does not advertise support
* for TLS compression, but alternative servers may support it.
* This was observed between early versions of the FreeRDP server
* and the FreeRDP client, and caused major performance issues,
* which is why we're disabling it.
*/
#ifdef SSL_OP_NO_COMPRESSION
options |= SSL_OP_NO_COMPRESSION;
#endif
/**
* SSL_OP_TLS_BLOCK_PADDING_BUG:
*
* The Microsoft RDP server does *not* support TLS padding.
* It absolutely needs to be disabled otherwise it won't work.
*/
options |= SSL_OP_TLS_BLOCK_PADDING_BUG;
/**
* SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS:
*
* Just like TLS padding, the Microsoft RDP server does not
* support empty fragments. This needs to be disabled.
*/
options |= SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS;
if (!tls_prepare(tls, underlying, TLSv1_client_method(), options, TRUE))
return FALSE;
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return tls_do_handshake(tls, TRUE);
}
BOOL tls_accept(rdpTls* tls, BIO *underlying, const char* cert_file, const char* privatekey_file)
{
long options = 0;
/**
* SSL_OP_NO_SSLv2:
*
* We only want SSLv3 and TLSv1, so disable SSLv2.
* SSLv3 is used by, eg. Microsoft RDC for Mac OS X.
*/
options |= SSL_OP_NO_SSLv2;
/**
* SSL_OP_NO_COMPRESSION:
*
* The Microsoft RDP server does not advertise support
* for TLS compression, but alternative servers may support it.
* This was observed between early versions of the FreeRDP server
* and the FreeRDP client, and caused major performance issues,
* which is why we're disabling it.
*/
#ifdef SSL_OP_NO_COMPRESSION
options |= SSL_OP_NO_COMPRESSION;
#endif
/**
* SSL_OP_TLS_BLOCK_PADDING_BUG:
*
* The Microsoft RDP server does *not* support TLS padding.
* It absolutely needs to be disabled otherwise it won't work.
*/
options |= SSL_OP_TLS_BLOCK_PADDING_BUG;
/**
* SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS:
*
* Just like TLS padding, the Microsoft RDP server does not
* support empty fragments. This needs to be disabled.
*/
options |= SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS;
if (!tls_prepare(tls, underlying, SSLv23_server_method(), options, FALSE))
return FALSE;
if (SSL_use_RSAPrivateKey_file(tls->ssl, privatekey_file, SSL_FILETYPE_PEM) <= 0)
{
WLog_ERR(TAG, "SSL_CTX_use_RSAPrivateKey_file failed");
WLog_ERR(TAG, "PrivateKeyFile: %s", privatekey_file);
return FALSE;
}
if (SSL_use_certificate_file(tls->ssl, cert_file, SSL_FILETYPE_PEM) <= 0)
{
WLog_ERR(TAG, "SSL_use_certificate_file failed");
return FALSE;
}
return tls_do_handshake(tls, FALSE) > 0;
}
BOOL tls_disconnect(rdpTls* tls)
{
if (!tls)
return FALSE;
if (!tls->ssl)
return TRUE;
if (tls->alertDescription != TLS_ALERT_DESCRIPTION_CLOSE_NOTIFY)
{
/**
* OpenSSL doesn't really expose an API for sending a TLS alert manually.
*
* The following code disables the sending of the default "close notify"
* and then proceeds to force sending a custom TLS alert before shutting down.
*
* Manually sending a TLS alert is necessary in certain cases,
* like when server-side NLA results in an authentication failure.
*/
SSL_set_quiet_shutdown(tls->ssl, 1);
if ((tls->alertLevel == TLS_ALERT_LEVEL_FATAL) && (tls->ssl->session))
SSL_CTX_remove_session(tls->ssl->ctx, tls->ssl->session);
tls->ssl->s3->alert_dispatch = 1;
tls->ssl->s3->send_alert[0] = tls->alertLevel;
tls->ssl->s3->send_alert[1] = tls->alertDescription;
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if (tls->ssl->s3->wbuf.left == 0)
tls->ssl->method->ssl_dispatch_alert(tls->ssl);
SSL_shutdown(tls->ssl);
}
else
{
SSL_shutdown(tls->ssl);
}
return TRUE;
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}
BIO *findBufferedBio(BIO *front)
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{
BIO *ret = front;
while (ret)
{
if (BIO_method_type(ret) == BIO_TYPE_BUFFERED)
return ret;
ret = ret->next_bio;
}
return ret;
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}
int tls_write_all(rdpTls* tls, const BYTE* data, int length)
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{
int status, nchunks, commitedBytes;
rdpTcp *tcp;
#ifdef HAVE_POLL_H
struct pollfd pollfds;
#else
fd_set rset, wset;
fd_set *rsetPtr, *wsetPtr;
struct timeval tv;
#endif
BIO* bio = tls->bio;
DataChunk chunks[2];
BIO* bufferedBio = findBufferedBio(bio);
if (!bufferedBio)
{
WLog_ERR(TAG, "error unable to retrieve the bufferedBio in the BIO chain");
return -1;
}
tcp = (rdpTcp*) bufferedBio->ptr;
do
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{
status = BIO_write(bio, data, length);
if (status > 0)
break;
if (!BIO_should_retry(bio))
return -1;
#ifdef HAVE_POLL_H
pollfds.fd = tcp->sockfd;
pollfds.revents = 0;
pollfds.events = 0;
if (tcp->writeBlocked)
{
pollfds.events |= POLLOUT;
}
else if (tcp->readBlocked)
{
pollfds.events |= POLLIN;
}
else
{
WLog_ERR(TAG, "weird we're blocked but the underlying is not read or write blocked !");
USleep(10);
continue;
}
do
{
status = poll(&pollfds, 1, 100);
}
while ((status < 0) && (errno == EINTR));
#else
/* we try to handle SSL want_read and want_write nicely */
rsetPtr = wsetPtr = NULL;
if (tcp->writeBlocked)
{
wsetPtr = &wset;
FD_ZERO(&wset);
FD_SET(tcp->sockfd, &wset);
}
else if (tcp->readBlocked)
{
rsetPtr = &rset;
FD_ZERO(&rset);
FD_SET(tcp->sockfd, &rset);
}
else
{
WLog_ERR(TAG, "weird we're blocked but the underlying is not read or write blocked !");
USleep(10);
continue;
}
tv.tv_sec = 0;
tv.tv_usec = 100 * 1000;
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status = _select(tcp->sockfd + 1, rsetPtr, wsetPtr, NULL, &tv);
#endif
if (status < 0)
return -1;
}
while (TRUE);
/* make sure the output buffer is empty */
commitedBytes = 0;
while ((nchunks = ringbuffer_peek(&tcp->xmitBuffer, chunks, ringbuffer_used(&tcp->xmitBuffer))))
{
int i;
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for (i = 0; i < nchunks; i++)
{
while (chunks[i].size)
{
status = BIO_write(tcp->socketBio, chunks[i].data, chunks[i].size);
if (status > 0)
{
chunks[i].size -= status;
chunks[i].data += status;
commitedBytes += status;
continue;
}
if (!BIO_should_retry(tcp->socketBio))
goto out_fail;
#ifdef HAVE_POLL_H
pollfds.fd = tcp->sockfd;
pollfds.events = POLLIN;
pollfds.revents = 0;
do
{
status = poll(&pollfds, 1, 100);
}
while ((status < 0) && (errno == EINTR));
#else
FD_ZERO(&rset);
FD_SET(tcp->sockfd, &rset);
tv.tv_sec = 0;
tv.tv_usec = 100 * 1000;
status = _select(tcp->sockfd + 1, &rset, NULL, NULL, &tv);
#endif
if (status < 0)
goto out_fail;
}
}
}
ringbuffer_commit_read_bytes(&tcp->xmitBuffer, commitedBytes);
return length;
out_fail:
ringbuffer_commit_read_bytes(&tcp->xmitBuffer, commitedBytes);
return -1;
}
int tls_set_alert_code(rdpTls* tls, int level, int description)
{
tls->alertLevel = level;
tls->alertDescription = description;
return 0;
}
BOOL tls_match_hostname(char *pattern, int pattern_length, char *hostname)
{
if (strlen(hostname) == pattern_length)
{
if (memcmp((void*) hostname, (void*) pattern, pattern_length) == 0)
return TRUE;
}
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if ((pattern_length > 2) && (pattern[0] == '*') && (pattern[1] == '.') && (((int) strlen(hostname)) >= pattern_length))
{
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char* check_hostname = &hostname[strlen(hostname) - pattern_length + 1];
if (memcmp((void*) check_hostname, (void*) &pattern[1], pattern_length - 1) == 0)
{
return TRUE;
}
}
return FALSE;
}
int tls_verify_certificate(rdpTls* tls, CryptoCert cert, char* hostname, int port)
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{
int match;
int index;
char* common_name = NULL;
int common_name_length = 0;
char** alt_names = NULL;
int alt_names_count = 0;
int* alt_names_lengths = NULL;
BOOL certificate_status;
BOOL hostname_match = FALSE;
BOOL verification_status = FALSE;
rdpCertificateData* certificate_data;
if (tls->settings->ExternalCertificateManagement)
{
BIO* bio;
int status;
int length;
int offset;
BYTE* pemCert;
freerdp* instance = (freerdp*) tls->settings->instance;
/**
* Don't manage certificates internally, leave it up entirely to the external client implementation
*/
bio = BIO_new(BIO_s_mem());
if (!bio)
{
WLog_ERR(TAG, "BIO_new() failure");
return -1;
}
status = PEM_write_bio_X509(bio, cert->px509);
if (status < 0)
{
WLog_ERR(TAG, "PEM_write_bio_X509 failure: %d", status);
return -1;
}
offset = 0;
length = 2048;
pemCert = (BYTE*) malloc(length + 1);
status = BIO_read(bio, pemCert, length);
if (status < 0)
{
WLog_ERR(TAG, "failed to read certificate");
return -1;
}
offset += status;
while (offset >= length)
{
length *= 2;
pemCert = (BYTE*) realloc(pemCert, length + 1);
status = BIO_read(bio, &pemCert[offset], length);
if (status < 0)
break;
offset += status;
}
if (status < 0)
{
WLog_ERR(TAG, "failed to read certificate");
return -1;
}
length = offset;
pemCert[length] = '\0';
status = -1;
if (instance->VerifyX509Certificate)
{
status = instance->VerifyX509Certificate(instance, pemCert, length, hostname, port, tls->isGatewayTransport);
}
WLog_ERR(TAG, "(length = %d) status: %d%s", length, status, pemCert);
free(pemCert);
BIO_free(bio);
if (status < 0)
return -1;
return (status == 0) ? 0 : 1;
}
/* ignore certificate verification if user explicitly required it (discouraged) */
if (tls->settings->IgnoreCertificate)
return 1; /* success! */
/* if user explicitly specified a certificate name, use it instead of the hostname */
if (tls->settings->CertificateName)
hostname = tls->settings->CertificateName;
/* attempt verification using OpenSSL and the ~/.freerdp/certs certificate store */
certificate_status = x509_verify_certificate(cert, tls->certificate_store->path);
/* verify certificate name match */
certificate_data = crypto_get_certificate_data(cert->px509, hostname);
/* extra common name and alternative names */
common_name = crypto_cert_subject_common_name(cert->px509, &common_name_length);
alt_names = crypto_cert_subject_alt_name(cert->px509, &alt_names_count, &alt_names_lengths);
/* compare against common name */
if (common_name)
{
if (tls_match_hostname(common_name, common_name_length, hostname))
hostname_match = TRUE;
}
/* compare against alternative names */
if (alt_names)
{
for (index = 0; index < alt_names_count; index++)
{
if (tls_match_hostname(alt_names[index], alt_names_lengths[index], hostname))
{
hostname_match = TRUE;
break;
}
}
}
/* if the certificate is valid and the certificate name matches, verification succeeds */
if (certificate_status && hostname_match)
{
if (common_name)
{
free(common_name);
common_name = NULL;
}
verification_status = TRUE; /* success! */
}
/* if the certificate is valid but the certificate name does not match, warn user, do not accept */
if (certificate_status && !hostname_match)
tls_print_certificate_name_mismatch_error(hostname, common_name, alt_names, alt_names_count);
/* verification could not succeed with OpenSSL, use known_hosts file and prompt user for manual verification */
if (!certificate_status)
{
char* issuer;
char* subject;
char* fingerprint;
freerdp* instance = (freerdp*) tls->settings->instance;
BOOL accept_certificate = FALSE;
issuer = crypto_cert_issuer(cert->px509);
subject = crypto_cert_subject(cert->px509);
fingerprint = crypto_cert_fingerprint(cert->px509);
/* search for matching entry in known_hosts file */
match = certificate_data_match(tls->certificate_store, certificate_data);
if (match == 1)
2011-08-29 00:46:36 +04:00
{
/* no entry was found in known_hosts file, prompt user for manual verification */
if (!hostname_match)
tls_print_certificate_name_mismatch_error(hostname, common_name, alt_names, alt_names_count);
if (instance->VerifyCertificate)
{
accept_certificate = instance->VerifyCertificate(instance, subject, issuer, fingerprint);
}
if (!accept_certificate)
{
/* user did not accept, abort and do not add entry in known_hosts file */
verification_status = FALSE; /* failure! */
}
else
{
/* user accepted certificate, add entry in known_hosts file */
certificate_data_print(tls->certificate_store, certificate_data);
verification_status = TRUE; /* success! */
}
2011-08-29 00:46:36 +04:00
}
else if (match == -1)
2011-08-29 00:46:36 +04:00
{
/* entry was found in known_hosts file, but fingerprint does not match. ask user to use it */
tls_print_certificate_error(hostname, fingerprint, tls->certificate_store->file);
if (instance->VerifyChangedCertificate)
{
accept_certificate = instance->VerifyChangedCertificate(instance, subject, issuer, fingerprint, "");
}
if (!accept_certificate)
{
/* user did not accept, abort and do not change known_hosts file */
verification_status = FALSE; /* failure! */
}
else
{
/* user accepted new certificate, add replace fingerprint for this host in known_hosts file */
certificate_data_replace(tls->certificate_store, certificate_data);
verification_status = TRUE; /* success! */
}
2011-08-29 00:46:36 +04:00
}
else if (match == 0)
{
verification_status = TRUE; /* success! */
}
free(issuer);
free(subject);
free(fingerprint);
}
if (certificate_data)
{
free(certificate_data->fingerprint);
free(certificate_data->hostname);
free(certificate_data);
2011-08-29 00:46:36 +04:00
}
2012-11-22 18:06:45 +04:00
#ifndef _WIN32
if (common_name)
free(common_name);
2012-11-22 18:06:45 +04:00
#endif
2013-08-28 19:10:58 +04:00
if (alt_names)
crypto_cert_subject_alt_name_free(alt_names_count, alt_names_lengths,
alt_names);
2013-08-28 19:10:58 +04:00
return (verification_status == 0) ? 0 : 1;
2011-08-29 00:46:36 +04:00
}
void tls_print_certificate_error(char* hostname, char* fingerprint, char *hosts_file)
{
WLog_ERR(TAG, "The host key for %s has changed", hostname);
WLog_ERR(TAG, "@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
WLog_ERR(TAG, "@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
WLog_ERR(TAG, "@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
WLog_ERR(TAG, "IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
WLog_ERR(TAG, "Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
WLog_ERR(TAG, "It is also possible that a host key has just been changed.");
WLog_ERR(TAG, "The fingerprint for the host key sent by the remote host is%s", fingerprint);
WLog_ERR(TAG, "Please contact your system administrator.");
WLog_ERR(TAG, "Add correct host key in %s to get rid of this message.", hosts_file);
WLog_ERR(TAG, "Host key for %s has changed and you have requested strict checking.", hostname);
WLog_ERR(TAG, "Host key verification failed.");
}
2011-07-04 01:29:09 +04:00
void tls_print_certificate_name_mismatch_error(char* hostname, char* common_name, char** alt_names, int alt_names_count)
{
int index;
assert(NULL != hostname);
WLog_ERR(TAG, "@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
WLog_ERR(TAG, "@ WARNING: CERTIFICATE NAME MISMATCH! @");
WLog_ERR(TAG, "@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
WLog_ERR(TAG, "The hostname used for this connection (%s) ", hostname);
WLog_ERR(TAG, "does not match %s given in the certificate:", alt_names_count < 1 ? "the name" : "any of the names");
WLog_ERR(TAG, "Common Name (CN):");
WLog_ERR(TAG, "\t%s", common_name ? common_name : "no CN found in certificate");
if (alt_names_count > 0)
{
assert(NULL != alt_names);
WLog_ERR(TAG, "Alternative names:");
for (index = 0; index < alt_names_count; index++)
{
assert(alt_names[index]);
WLog_ERR(TAG, "\t %s", alt_names[index]);
}
}
WLog_ERR(TAG, "A valid certificate for the wrong name should NOT be trusted!");
}
rdpTls* tls_new(rdpSettings* settings)
{
rdpTls* tls;
tls = (rdpTls*) calloc(1, sizeof(rdpTls));
if (!tls)
return NULL;
OpenSSL thread safety freerdp/winpr had the following issues: * The non reentrant SSL_library_init() was called concurrently (crash) * Missing code/api to set the eventually required OpenSSL static and dynamic locking callbacks * Missing code/api to free the application-global or thread-local OpenSSL data and tables This commit creates two new winpr functions: BOOL winpr_InitializeSSL(DWORD flags): Use the flag WINPR_SSL_INIT_ALREADY_INITIALIZED if you want to tell winpr that your application has already initialized OpenSSL. If required use the flag WINPR_SSL_INIT_ENABLE_LOCKING to tell winpr that it should set the OpenSSL static and dynamic locking callbacks. Otherwise just call it with the flag WINPR_SSL_INIT_DEFAULT. The recommended way is that your application calls this function once before any threads are created. However, in order to support lazy OpenSSL library initialization winpr_InitializeSSL() can also safely be called multiple times and concurrently because it uses the new InitOnceExecuteOnce() function to guarantee that the initialization is only performed successfully once during the life time of the calling process. BOOL winpr_CleanupSSL(DWORD flags): If you create a thread that uses SSL you should call this function before the thread returns using the flag WINPR_SSL_CLEANUP_THREAD in order to clean up the thread-local OpenSSL data and tables. Call the function with the flag WINPR_SSL_CLEANUP_GLOBAL before terminating your application. Note: This commit only replaced the current occurences of the SSL_load_error_strings(); SSL_library_init(); pairs in the freerdp source with winpr_InitializeSSL(). None of the server or client applications has been changed according to the recommended usage described above (TBDL).
2014-07-28 23:55:57 +04:00
winpr_InitializeSSL(WINPR_SSL_INIT_DEFAULT);
tls->settings = settings;
if (!settings->ServerMode)
{
tls->certificate_store = certificate_store_new(settings);
if (!tls->certificate_store)
goto out_free;
}
tls->alertLevel = TLS_ALERT_LEVEL_WARNING;
tls->alertDescription = TLS_ALERT_DESCRIPTION_CLOSE_NOTIFY;
return tls;
out_free:
free(tls);
return NULL;
}
void tls_free(rdpTls* tls)
2011-07-04 01:29:09 +04:00
{
if (!tls)
return;
if (tls->ctx)
{
SSL_CTX_free(tls->ctx);
tls->ctx = NULL;
}
if (tls->PublicKey)
{
free(tls->PublicKey);
tls->PublicKey = NULL;
}
if (tls->Bindings)
{
free(tls->Bindings->Bindings);
free(tls->Bindings);
tls->Bindings = NULL;
}
2013-01-26 02:52:37 +04:00
if (tls->certificate_store)
{
certificate_store_free(tls->certificate_store);
tls->certificate_store = NULL;
}
free(tls);
2011-07-04 01:29:09 +04:00
}