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FreeRDP/libfreerdp/crypto/tls.c

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/**
* FreeRDP: A Remote Desktop Protocol Implementation
* Transport Layer Security
*
* Copyright 2011-2012 Marc-Andre Moreau <marcandre.moreau@gmail.com>
* Copyright 2023 Armin Novak <anovak@thincast.com>
* Copyright 2023 Thincast Technologies GmbH
*
* 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
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* 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.
*/
#include <freerdp/config.h>
#include "../core/settings.h"
#include <winpr/assert.h>
#include <string.h>
#include <errno.h>
#include <winpr/crt.h>
#include <winpr/string.h>
#include <winpr/sspi.h>
#include <winpr/ssl.h>
#include <winpr/stream.h>
#include <freerdp/utils/ringbuffer.h>
#include <freerdp/crypto/certificate.h>
#include <freerdp/crypto/certificate_data.h>
#include <freerdp/log.h>
#include "../crypto/tls.h"
#include "../core/tcp.h"
#include "opensslcompat.h"
#include "certificate.h"
#include "privatekey.h"
#ifdef WINPR_HAVE_POLL_H
#include <poll.h>
#endif
#ifdef FREERDP_HAVE_VALGRIND_MEMCHECK_H
#include <valgrind/memcheck.h>
#endif
#define TAG FREERDP_TAG("crypto")
/**
* Earlier Microsoft iOS RDP clients have sent a null or even double null
* terminated hostname in the SNI TLS extension.
* If the length indicator does not equal the hostname strlen OpenSSL
* will abort (see openssl:ssl/t1_lib.c).
* Here is a tcpdump segment of Microsoft Remote Desktop Client Version
* 8.1.7 running on an iPhone 4 with iOS 7.1.2 showing the transmitted
* SNI hostname TLV blob when connection to server "abcd":
* 00 name_type 0x00 (host_name)
* 00 06 length_in_bytes 0x0006
* 61 62 63 64 00 00 host_name "abcd\0\0"
*
* Currently the only (runtime) workaround is setting an openssl tls
* extension debug callback that sets the SSL context's servername_done
* to 1 which effectively disables the parsing of that extension type.
*
* Nowadays this workaround is not required anymore but still can be
* activated by adding the following define:
*
* #define MICROSOFT_IOS_SNI_BUG
*/
typedef struct
{
SSL* ssl;
CRITICAL_SECTION lock;
} BIO_RDP_TLS;
static int tls_verify_certificate(rdpTls* tls, const rdpCertificate* cert, const char* hostname,
UINT16 port);
static void tls_print_certificate_name_mismatch_error(const char* hostname, UINT16 port,
const char* common_name, char** alt_names,
size_t alt_names_count);
static void tls_print_new_certificate_warn(rdpCertificateStore* store, const char* hostname,
UINT16 port, const char* fingerprint);
static void tls_print_certificate_error(rdpCertificateStore* store, rdpCertificateData* stored_data,
const char* hostname, UINT16 port, const char* fingerprint);
static void free_tls_public_key(rdpTls* tls)
{
WINPR_ASSERT(tls);
free(tls->PublicKey);
tls->PublicKey = NULL;
tls->PublicKeyLength = 0;
}
static void free_tls_bindings(rdpTls* tls)
{
WINPR_ASSERT(tls);
if (tls->Bindings)
free(tls->Bindings->Bindings);
free(tls->Bindings);
tls->Bindings = NULL;
}
static int bio_rdp_tls_write(BIO* bio, const char* buf, int size)
{
int error = 0;
int status = 0;
BIO_RDP_TLS* tls = (BIO_RDP_TLS*)BIO_get_data(bio);
if (!buf || !tls)
return 0;
BIO_clear_flags(bio, BIO_FLAGS_WRITE | BIO_FLAGS_READ | BIO_FLAGS_IO_SPECIAL);
EnterCriticalSection(&tls->lock);
status = SSL_write(tls->ssl, buf, size);
error = SSL_get_error(tls->ssl, status);
LeaveCriticalSection(&tls->lock);
if (status <= 0)
{
switch (error)
{
case SSL_ERROR_NONE:
BIO_clear_flags(bio, 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_READ:
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_set_retry_reason(bio, BIO_RR_SSL_X509_LOOKUP);
break;
case SSL_ERROR_WANT_CONNECT:
BIO_set_flags(bio, BIO_FLAGS_IO_SPECIAL);
BIO_set_retry_reason(bio, BIO_RR_CONNECT);
break;
case SSL_ERROR_SYSCALL:
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)
{
int error = 0;
int status = 0;
BIO_RDP_TLS* tls = (BIO_RDP_TLS*)BIO_get_data(bio);
if (!buf || !tls)
return 0;
BIO_clear_flags(bio, BIO_FLAGS_WRITE | BIO_FLAGS_READ | BIO_FLAGS_IO_SPECIAL);
EnterCriticalSection(&tls->lock);
status = SSL_read(tls->ssl, buf, size);
error = SSL_get_error(tls->ssl, status);
LeaveCriticalSection(&tls->lock);
if (status <= 0)
{
switch (error)
{
case SSL_ERROR_NONE:
BIO_clear_flags(bio, BIO_FLAGS_SHOULD_RETRY);
break;
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_X509_LOOKUP:
BIO_set_flags(bio, BIO_FLAGS_IO_SPECIAL);
BIO_set_retry_reason(bio, BIO_RR_SSL_X509_LOOKUP);
break;
case SSL_ERROR_WANT_ACCEPT:
BIO_set_flags(bio, BIO_FLAGS_IO_SPECIAL);
BIO_set_retry_reason(bio, BIO_RR_ACCEPT);
break;
case SSL_ERROR_WANT_CONNECT:
BIO_set_flags(bio, BIO_FLAGS_IO_SPECIAL);
BIO_set_retry_reason(bio, 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:
BIO_clear_flags(bio, BIO_FLAGS_SHOULD_RETRY);
break;
}
}
#ifdef FREERDP_HAVE_VALGRIND_MEMCHECK_H
if (status > 0)
{
VALGRIND_MAKE_MEM_DEFINED(buf, status);
}
#endif
return status;
}
static int bio_rdp_tls_puts(BIO* bio, const char* str)
{
size_t size = 0;
int status = 0;
if (!str)
return 0;
size = strlen(str);
ERR_clear_error();
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* ssl_rbio = NULL;
BIO* ssl_wbio = NULL;
BIO* next_bio = NULL;
int status = -1;
BIO_RDP_TLS* tls = (BIO_RDP_TLS*)BIO_get_data(bio);
if (!tls)
return 0;
if (!tls->ssl && (cmd != BIO_C_SET_SSL))
return 0;
next_bio = BIO_next(bio);
ssl_rbio = tls->ssl ? SSL_get_rbio(tls->ssl) : NULL;
ssl_wbio = tls->ssl ? SSL_get_wbio(tls->ssl) : NULL;
switch (cmd)
{
case BIO_CTRL_RESET:
SSL_shutdown(tls->ssl);
if (SSL_in_connect_init(tls->ssl))
SSL_set_connect_state(tls->ssl);
else if (SSL_in_accept_init(tls->ssl))
SSL_set_accept_state(tls->ssl);
SSL_clear(tls->ssl);
if (next_bio)
status = BIO_ctrl(next_bio, cmd, num, ptr);
else if (ssl_rbio)
status = BIO_ctrl(ssl_rbio, cmd, num, ptr);
else
status = 1;
break;
case BIO_C_GET_FD:
status = BIO_ctrl(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_get_shutdown(bio);
break;
case BIO_CTRL_SET_CLOSE:
BIO_set_shutdown(bio, (int)num);
status = 1;
break;
case BIO_CTRL_WPENDING:
status = BIO_ctrl(ssl_wbio, cmd, num, ptr);
break;
case BIO_CTRL_PENDING:
status = SSL_pending(tls->ssl);
if (status == 0)
status = BIO_pending(ssl_rbio);
break;
case BIO_CTRL_FLUSH:
BIO_clear_retry_flags(bio);
status = BIO_ctrl(ssl_wbio, cmd, num, ptr);
if (status != 1)
WLog_DBG(TAG, "BIO_ctrl returned %d", status);
BIO_copy_next_retry(bio);
status = 1;
break;
case BIO_CTRL_PUSH:
if (next_bio && (next_bio != ssl_rbio))
{
#if OPENSSL_VERSION_NUMBER < 0x10100000L || \
(defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x2070000fL)
SSL_set_bio(tls->ssl, next_bio, next_bio);
CRYPTO_add(&(bio->next_bio->references), 1, CRYPTO_LOCK_BIO);
#else
/*
* We are going to pass ownership of next to the SSL object...but
* we don't own a reference to pass yet - so up ref
*/
BIO_up_ref(next_bio);
SSL_set_bio(tls->ssl, next_bio, next_bio);
#endif
}
status = 1;
break;
case BIO_CTRL_POP:
/* Only detach if we are the BIO explicitly being popped */
if (bio == ptr)
{
if (ssl_rbio != ssl_wbio)
BIO_free_all(ssl_wbio);
#if OPENSSL_VERSION_NUMBER < 0x10100000L || \
(defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x2070000fL)
if (next_bio)
CRYPTO_add(&(bio->next_bio->references), -1, CRYPTO_LOCK_BIO);
tls->ssl->wbio = tls->ssl->rbio = NULL;
#else
/* OpenSSL 1.1: This will also clear the reference we obtained during push */
SSL_set_bio(tls->ssl, NULL, NULL);
#endif
}
status = 1;
break;
case BIO_C_GET_SSL:
if (ptr)
{
*((SSL**)ptr) = tls->ssl;
status = 1;
}
break;
case BIO_C_SET_SSL:
BIO_set_shutdown(bio, (int)num);
if (ptr)
{
tls->ssl = (SSL*)ptr;
ssl_rbio = SSL_get_rbio(tls->ssl);
}
if (ssl_rbio)
{
if (next_bio)
BIO_push(ssl_rbio, next_bio);
BIO_set_next(bio, ssl_rbio);
#if OPENSSL_VERSION_NUMBER < 0x10100000L || \
(defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x2070000fL)
CRYPTO_add(&(ssl_rbio->references), 1, CRYPTO_LOCK_BIO);
#else
BIO_up_ref(ssl_rbio);
#endif
}
BIO_set_init(bio, 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_set_retry_reason(bio, 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_set_retry_reason(bio, BIO_get_retry_reason(next_bio));
break;
default:
BIO_clear_flags(bio, BIO_FLAGS_SHOULD_RETRY);
break;
}
}
break;
default:
status = BIO_ctrl(ssl_rbio, cmd, num, ptr);
break;
}
return status;
}
static int bio_rdp_tls_new(BIO* bio)
{
BIO_RDP_TLS* tls = NULL;
BIO_set_flags(bio, BIO_FLAGS_SHOULD_RETRY);
if (!(tls = calloc(1, sizeof(BIO_RDP_TLS))))
return 0;
InitializeCriticalSectionAndSpinCount(&tls->lock, 4000);
BIO_set_data(bio, (void*)tls);
return 1;
}
static int bio_rdp_tls_free(BIO* bio)
{
BIO_RDP_TLS* tls = NULL;
if (!bio)
return 0;
tls = (BIO_RDP_TLS*)BIO_get_data(bio);
if (!tls)
return 0;
BIO_set_data(bio, NULL);
if (BIO_get_shutdown(bio))
{
if (BIO_get_init(bio) && tls->ssl)
{
SSL_shutdown(tls->ssl);
SSL_free(tls->ssl);
}
BIO_set_init(bio, 0);
BIO_set_flags(bio, 0);
}
DeleteCriticalSection(&tls->lock);
free(tls);
return 1;
}
static long bio_rdp_tls_callback_ctrl(BIO* bio, int cmd, bio_info_cb* fp)
{
long status = 0;
BIO_RDP_TLS* tls = NULL;
if (!bio)
return 0;
tls = (BIO_RDP_TLS*)BIO_get_data(bio);
if (!tls)
return 0;
switch (cmd)
{
case BIO_CTRL_SET_CALLBACK:
{
typedef void (*fkt_t)(const SSL*, int, int);
/* Documented since https://www.openssl.org/docs/man1.1.1/man3/BIO_set_callback.html
* the argument is not really of type bio_info_cb* and must be cast
* to the required type */
fkt_t fkt = (fkt_t)(void*)fp;
SSL_set_info_callback(tls->ssl, fkt);
status = 1;
}
break;
default:
status = BIO_callback_ctrl(SSL_get_rbio(tls->ssl), cmd, fp);
break;
}
return status;
}
#define BIO_TYPE_RDP_TLS 68
static BIO_METHOD* BIO_s_rdp_tls(void)
{
static BIO_METHOD* bio_methods = NULL;
if (bio_methods == NULL)
{
if (!(bio_methods = BIO_meth_new(BIO_TYPE_RDP_TLS, "RdpTls")))
return NULL;
BIO_meth_set_write(bio_methods, bio_rdp_tls_write);
BIO_meth_set_read(bio_methods, bio_rdp_tls_read);
BIO_meth_set_puts(bio_methods, bio_rdp_tls_puts);
BIO_meth_set_gets(bio_methods, bio_rdp_tls_gets);
BIO_meth_set_ctrl(bio_methods, bio_rdp_tls_ctrl);
BIO_meth_set_create(bio_methods, bio_rdp_tls_new);
BIO_meth_set_destroy(bio_methods, bio_rdp_tls_free);
BIO_meth_set_callback_ctrl(bio_methods, bio_rdp_tls_callback_ctrl);
}
return bio_methods;
}
static BIO* BIO_new_rdp_tls(SSL_CTX* ctx, int client)
{
BIO* bio = NULL;
SSL* ssl = NULL;
bio = BIO_new(BIO_s_rdp_tls());
if (!bio)
return NULL;
ssl = SSL_new(ctx);
if (!ssl)
{
BIO_free_all(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 rdpCertificate* tls_get_certificate(rdpTls* tls, BOOL peer)
{
X509* remote_cert = NULL;
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;
}
/* Get the peer's chain. If it does not exist, we're setting NULL (clean data either way) */
STACK_OF(X509)* chain = SSL_get_peer_cert_chain(tls->ssl);
rdpCertificate* cert = freerdp_certificate_new_from_x509(remote_cert, chain);
X509_free(remote_cert);
return cert;
}
static const char* tls_get_server_name(rdpTls* tls)
{
return tls->serverName ? tls->serverName : tls->hostname;
}
#define TLS_SERVER_END_POINT "tls-server-end-point:"
static SecPkgContext_Bindings* tls_get_channel_bindings(const rdpCertificate* cert)
{
size_t CertificateHashLength = 0;
BYTE* ChannelBindingToken = NULL;
UINT32 ChannelBindingTokenLength = 0;
SEC_CHANNEL_BINDINGS* ChannelBindings = NULL;
SecPkgContext_Bindings* ContextBindings = NULL;
const size_t PrefixLength = strnlen(TLS_SERVER_END_POINT, ARRAYSIZE(TLS_SERVER_END_POINT));
WINPR_ASSERT(cert);
/* See https://www.rfc-editor.org/rfc/rfc5929 for details about hashes */
WINPR_MD_TYPE alg = freerdp_certificate_get_signature_alg(cert);
const char* hash = NULL;
switch (alg)
{
case WINPR_MD_MD5:
case WINPR_MD_SHA1:
hash = winpr_md_type_to_string(WINPR_MD_SHA256);
break;
default:
hash = winpr_md_type_to_string(alg);
break;
}
if (!hash)
return NULL;
char* CertificateHash = freerdp_certificate_get_hash(cert, hash, &CertificateHashLength);
if (!CertificateHash)
return NULL;
ChannelBindingTokenLength = PrefixLength + CertificateHashLength;
ContextBindings = (SecPkgContext_Bindings*)calloc(1, sizeof(SecPkgContext_Bindings));
if (!ContextBindings)
goto out_free;
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];
memcpy(ChannelBindingToken, TLS_SERVER_END_POINT, PrefixLength);
memcpy(ChannelBindingToken + PrefixLength, CertificateHash, CertificateHashLength);
free(CertificateHash);
return ContextBindings;
out_free:
free(CertificateHash);
free(ContextBindings);
return NULL;
}
static INIT_ONCE secrets_file_idx_once = INIT_ONCE_STATIC_INIT;
static int secrets_file_idx = -1;
static BOOL CALLBACK secrets_file_init_cb(PINIT_ONCE once, PVOID param, PVOID* context)
{
secrets_file_idx = SSL_get_ex_new_index(0, NULL, NULL, NULL, NULL);
return (secrets_file_idx != -1);
}
static void SSLCTX_keylog_cb(const SSL* ssl, const char* line)
{
char* dfile = NULL;
if (secrets_file_idx == -1)
return;
dfile = SSL_get_ex_data(ssl, secrets_file_idx);
if (dfile)
{
FILE* f = winpr_fopen(dfile, "a+");
if (f)
{
(void)fwrite(line, strlen(line), 1, f);
(void)fwrite("\n", 1, 1, f);
(void)fclose(f);
}
}
}
static void tls_reset(rdpTls* tls)
{
WINPR_ASSERT(tls);
if (tls->ctx)
{
SSL_CTX_free(tls->ctx);
tls->ctx = NULL;
}
/* tls->underlying is a stacked BIO under tls->bio.
* BIO_free_all will free recursivly. */
if (tls->bio)
BIO_free_all(tls->bio);
else if (tls->underlying)
BIO_free_all(tls->underlying);
tls->bio = NULL;
tls->underlying = NULL;
free_tls_public_key(tls);
free_tls_bindings(tls);
}
#if OPENSSL_VERSION_NUMBER >= 0x010000000L
static BOOL tls_prepare(rdpTls* tls, BIO* underlying, const SSL_METHOD* method, int options,
BOOL clientMode)
#else
static BOOL tls_prepare(rdpTls* tls, BIO* underlying, SSL_METHOD* method, int options,
BOOL clientMode)
#endif
{
WINPR_ASSERT(tls);
rdpSettings* settings = tls->context->settings;
WINPR_ASSERT(settings);
tls_reset(tls);
tls->ctx = SSL_CTX_new(method);
tls->underlying = underlying;
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 OPENSSL_VERSION_NUMBER >= 0x10100000L || defined(LIBRESSL_VERSION_NUMBER)
UINT16 version = freerdp_settings_get_uint16(settings, FreeRDP_TLSMinVersion);
if (!SSL_CTX_set_min_proto_version(tls->ctx, version))
{
WLog_ERR(TAG, "SSL_CTX_set_min_proto_version %s failed", version);
return FALSE;
}
version = freerdp_settings_get_uint16(settings, FreeRDP_TLSMaxVersion);
if (!SSL_CTX_set_max_proto_version(tls->ctx, version))
{
WLog_ERR(TAG, "SSL_CTX_set_max_proto_version %s failed", version);
return FALSE;
}
#endif
#if OPENSSL_VERSION_NUMBER >= 0x10100000L && !defined(LIBRESSL_VERSION_NUMBER)
SSL_CTX_set_security_level(tls->ctx, settings->TlsSecLevel);
#endif
if (settings->AllowedTlsCiphers)
{
if (!SSL_CTX_set_cipher_list(tls->ctx, settings->AllowedTlsCiphers))
{
WLog_ERR(TAG, "SSL_CTX_set_cipher_list %s failed", settings->AllowedTlsCiphers);
return FALSE;
}
}
tls->bio = BIO_new_rdp_tls(tls->ctx, clientMode);
if (BIO_get_ssl(tls->bio, &tls->ssl) < 0)
{
WLog_ERR(TAG, "unable to retrieve the SSL of the connection");
return FALSE;
}
if (settings->TlsSecretsFile)
{
#if OPENSSL_VERSION_NUMBER >= 0x10101000L
InitOnceExecuteOnce(&secrets_file_idx_once, secrets_file_init_cb, NULL, NULL);
if (secrets_file_idx != -1)
{
SSL_set_ex_data(tls->ssl, secrets_file_idx, settings->TlsSecretsFile);
SSL_CTX_set_keylog_callback(tls->ctx, SSLCTX_keylog_cb);
}
#else
WLog_WARN(TAG, "Key-Logging not available - requires OpenSSL 1.1.1 or higher");
#endif
}
BIO_push(tls->bio, underlying);
return TRUE;
}
static void adjustSslOptions(int* options)
{
WINPR_ASSERT(options);
#if OPENSSL_VERSION_NUMBER < 0x10100000L || defined(LIBRESSL_VERSION_NUMBER)
*options |= SSL_OP_NO_SSLv2;
*options |= SSL_OP_NO_SSLv3;
#endif
}
const SSL_METHOD* freerdp_tls_get_ssl_method(BOOL isDtls, BOOL isClient)
{
if (isClient)
{
if (isDtls)
return DTLS_client_method();
#if OPENSSL_VERSION_NUMBER < 0x10100000L || defined(LIBRESSL_VERSION_NUMBER)
return SSLv23_client_method();
#else
return TLS_client_method();
#endif
}
if (isDtls)
return DTLS_server_method();
#if OPENSSL_VERSION_NUMBER < 0x10100000L || defined(LIBRESSL_VERSION_NUMBER)
return SSLv23_server_method();
#else
return TLS_server_method();
#endif
}
TlsHandshakeResult freerdp_tls_connect_ex(rdpTls* tls, BIO* underlying, const SSL_METHOD* methods)
{
WINPR_ASSERT(tls);
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;
tls->isClientMode = TRUE;
adjustSslOptions(&options);
if (!tls_prepare(tls, underlying, methods, options, TRUE))
return 0;
#if !defined(OPENSSL_NO_TLSEXT) && !defined(LIBRESSL_VERSION_NUMBER)
SSL_set_tlsext_host_name(tls->ssl, tls_get_server_name(tls));
#endif
return freerdp_tls_handshake(tls);
}
static int bio_err_print(const char* str, size_t len, void* u)
{
wLog* log = u;
WLog_Print(log, WLOG_ERROR, "[BIO_do_handshake] %s [%" PRIuz "]", str, len);
return 0;
}
TlsHandshakeResult freerdp_tls_handshake(rdpTls* tls)
{
TlsHandshakeResult ret = TLS_HANDSHAKE_ERROR;
WINPR_ASSERT(tls);
int status = BIO_do_handshake(tls->bio);
if (status != 1)
{
if (!BIO_should_retry(tls->bio))
{
wLog* log = WLog_Get(TAG);
WLog_Print(log, WLOG_ERROR, "BIO_do_handshake failed");
ERR_print_errors_cb(bio_err_print, log);
return TLS_HANDSHAKE_ERROR;
}
return TLS_HANDSHAKE_CONTINUE;
}
int verify_status = 0;
rdpCertificate* cert = tls_get_certificate(tls, tls->isClientMode);
if (!cert)
{
WLog_ERR(TAG, "tls_get_certificate failed to return the server certificate.");
return TLS_HANDSHAKE_ERROR;
}
do
{
free_tls_bindings(tls);
tls->Bindings = tls_get_channel_bindings(cert);
if (!tls->Bindings)
{
WLog_ERR(TAG, "unable to retrieve bindings");
break;
}
free_tls_public_key(tls);
if (!freerdp_certificate_get_public_key(cert, &tls->PublicKey, &tls->PublicKeyLength))
{
WLog_ERR(TAG,
"freerdp_certificate_get_public_key failed to return the server public key.");
break;
}
/* server-side NLA needs public keys (keys from us, the server) but no certificate verify */
ret = TLS_HANDSHAKE_SUCCESS;
if (tls->isClientMode)
{
verify_status = tls_verify_certificate(tls, cert, tls_get_server_name(tls), tls->port);
if (verify_status < 1)
{
WLog_ERR(TAG, "certificate not trusted, aborting.");
freerdp_tls_send_alert(tls);
ret = TLS_HANDSHAKE_VERIFY_ERROR;
}
}
} while (0);
freerdp_certificate_free(cert);
return ret;
}
static int pollAndHandshake(rdpTls* tls)
{
WINPR_ASSERT(tls);
do
{
HANDLE event = NULL;
DWORD status = 0;
if (BIO_get_event(tls->bio, &event) < 0)
{
WLog_ERR(TAG, "unable to retrieve BIO associated event");
return -1;
}
if (!event)
{
WLog_ERR(TAG, "unable to retrieve BIO event");
return -1;
}
status = WaitForSingleObjectEx(event, 50, TRUE);
switch (status)
{
case WAIT_OBJECT_0:
break;
case WAIT_TIMEOUT:
case WAIT_IO_COMPLETION:
continue;
default:
WLog_ERR(TAG, "error during WaitForSingleObject(): 0x%08" PRIX32 "", status);
return -1;
}
TlsHandshakeResult result = freerdp_tls_handshake(tls);
switch (result)
{
case TLS_HANDSHAKE_CONTINUE:
break;
case TLS_HANDSHAKE_SUCCESS:
return 1;
case TLS_HANDSHAKE_ERROR:
case TLS_HANDSHAKE_VERIFY_ERROR:
default:
return -1;
}
} while (TRUE);
}
int freerdp_tls_connect(rdpTls* tls, BIO* underlying)
{
const SSL_METHOD* method = freerdp_tls_get_ssl_method(FALSE, TRUE);
WINPR_ASSERT(tls);
TlsHandshakeResult result = freerdp_tls_connect_ex(tls, underlying, method);
switch (result)
{
case TLS_HANDSHAKE_SUCCESS:
return 1;
case TLS_HANDSHAKE_CONTINUE:
break;
case TLS_HANDSHAKE_ERROR:
case TLS_HANDSHAKE_VERIFY_ERROR:
return -1;
}
return pollAndHandshake(tls);
}
#if defined(MICROSOFT_IOS_SNI_BUG) && !defined(OPENSSL_NO_TLSEXT) && \
!defined(LIBRESSL_VERSION_NUMBER)
static void tls_openssl_tlsext_debug_callback(SSL* s, int client_server, int type,
unsigned char* data, int len, void* arg)
{
if (type == TLSEXT_TYPE_server_name)
{
WLog_DBG(TAG, "Client uses SNI (extension disabled)");
s->servername_done = 2;
}
}
#endif
BOOL freerdp_tls_accept(rdpTls* tls, BIO* underlying, rdpSettings* settings)
{
WINPR_ASSERT(tls);
TlsHandshakeResult res =
freerdp_tls_accept_ex(tls, underlying, settings, freerdp_tls_get_ssl_method(FALSE, FALSE));
switch (res)
{
case TLS_HANDSHAKE_SUCCESS:
return TRUE;
case TLS_HANDSHAKE_CONTINUE:
break;
case TLS_HANDSHAKE_ERROR:
case TLS_HANDSHAKE_VERIFY_ERROR:
default:
return FALSE;
}
return pollAndHandshake(tls) > 0;
}
TlsHandshakeResult freerdp_tls_accept_ex(rdpTls* tls, BIO* underlying, rdpSettings* settings,
const SSL_METHOD* methods)
{
WINPR_ASSERT(tls);
long options = 0;
int status = 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;
/**
* SSL_OP_NO_RENEGOTIATION
*
* Disable SSL client site renegotiation.
*/
#if (OPENSSL_VERSION_NUMBER >= 0x10101000L) && (OPENSSL_VERSION_NUMBER < 0x30000000L) && \
!defined(LIBRESSL_VERSION_NUMBER)
options |= SSL_OP_NO_RENEGOTIATION;
#endif
if (!tls_prepare(tls, underlying, methods, options, FALSE))
return TLS_HANDSHAKE_ERROR;
const rdpPrivateKey* key = freerdp_settings_get_pointer(settings, FreeRDP_RdpServerRsaKey);
if (!key)
{
WLog_ERR(TAG, "invalid private key");
return TLS_HANDSHAKE_ERROR;
}
EVP_PKEY* privkey = freerdp_key_get_evp_pkey(key);
if (!privkey)
{
WLog_ERR(TAG, "invalid private key");
return TLS_HANDSHAKE_ERROR;
}
status = SSL_use_PrivateKey(tls->ssl, privkey);
/* The local reference to the private key will anyway go out of
* scope; so the reference count should be decremented weither
* SSL_use_PrivateKey succeeds or fails.
*/
EVP_PKEY_free(privkey);
if (status <= 0)
{
WLog_ERR(TAG, "SSL_CTX_use_PrivateKey_file failed");
return TLS_HANDSHAKE_ERROR;
}
rdpCertificate* cert =
freerdp_settings_get_pointer_writable(settings, FreeRDP_RdpServerCertificate);
if (!cert)
{
WLog_ERR(TAG, "invalid certificate");
return TLS_HANDSHAKE_ERROR;
}
status = SSL_use_certificate(tls->ssl, freerdp_certificate_get_x509(cert));
if (status <= 0)
{
WLog_ERR(TAG, "SSL_use_certificate_file failed");
return TLS_HANDSHAKE_ERROR;
}
#if defined(MICROSOFT_IOS_SNI_BUG) && !defined(OPENSSL_NO_TLSEXT) && \
!defined(LIBRESSL_VERSION_NUMBER)
SSL_set_tlsext_debug_callback(tls->ssl, tls_openssl_tlsext_debug_callback);
#endif
return freerdp_tls_handshake(tls);
}
BOOL freerdp_tls_send_alert(rdpTls* tls)
{
WINPR_ASSERT(tls);
if (!tls)
return FALSE;
if (!tls->ssl)
return TRUE;
/**
* FIXME: The following code does not work on OpenSSL > 1.1.0 because the
* SSL struct is opaqe now
*/
#if (!defined(LIBRESSL_VERSION_NUMBER) && (OPENSSL_VERSION_NUMBER < 0x10100000L)) || \
(defined(LIBRESSL_VERSION_NUMBER) && (LIBRESSL_VERSION_NUMBER <= 0x2080300fL))
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_SESSION* ssl_session = SSL_get_session(tls->ssl);
SSL_CTX* ssl_ctx = SSL_get_SSL_CTX(tls->ssl);
SSL_set_quiet_shutdown(tls->ssl, 1);
if ((tls->alertLevel == TLS_ALERT_LEVEL_FATAL) && (ssl_session))
SSL_CTX_remove_session(ssl_ctx, ssl_session);
tls->ssl->s3->alert_dispatch = 1;
tls->ssl->s3->send_alert[0] = tls->alertLevel;
tls->ssl->s3->send_alert[1] = tls->alertDescription;
if (tls->ssl->s3->wbuf.left == 0)
tls->ssl->method->ssl_dispatch_alert(tls->ssl);
}
#endif
return TRUE;
}
int freerdp_tls_write_all(rdpTls* tls, const BYTE* data, int length)
{
WINPR_ASSERT(tls);
int status = 0;
int offset = 0;
BIO* bio = tls->bio;
while (offset < length)
{
ERR_clear_error();
status = BIO_write(bio, &data[offset], length - offset);
if (status > 0)
{
offset += status;
}
else
{
if (!BIO_should_retry(bio))
return -1;
if (BIO_write_blocked(bio))
status = BIO_wait_write(bio, 100);
else if (BIO_read_blocked(bio))
return -2; /* Abort write, there is data that must be read */
else
USleep(100);
if (status < 0)
return -1;
}
}
return length;
}
int freerdp_tls_set_alert_code(rdpTls* tls, int level, int description)
{
WINPR_ASSERT(tls);
tls->alertLevel = level;
tls->alertDescription = description;
return 0;
}
static BOOL tls_match_hostname(const char* pattern, const size_t pattern_length,
const char* hostname)
{
if (strlen(hostname) == pattern_length)
{
if (_strnicmp(hostname, pattern, pattern_length) == 0)
return TRUE;
}
if ((pattern_length > 2) && (pattern[0] == '*') && (pattern[1] == '.') &&
((strlen(hostname)) >= pattern_length))
{
const char* check_hostname = &hostname[strlen(hostname) - pattern_length + 1];
if (_strnicmp(check_hostname, &pattern[1], pattern_length - 1) == 0)
{
return TRUE;
}
}
return FALSE;
}
static BOOL is_redirected(rdpTls* tls)
{
rdpSettings* settings = tls->context->settings;
if (LB_NOREDIRECT & settings->RedirectionFlags)
return FALSE;
return settings->RedirectionFlags != 0;
}
static BOOL is_accepted(rdpTls* tls, const rdpCertificate* cert)
{
WINPR_ASSERT(tls);
WINPR_ASSERT(tls->context);
WINPR_ASSERT(cert);
rdpSettings* settings = tls->context->settings;
WINPR_ASSERT(settings);
FreeRDP_Settings_Keys_String keyAccepted = FreeRDP_AcceptedCert;
FreeRDP_Settings_Keys_UInt32 keyLength = FreeRDP_AcceptedCertLength;
if (tls->isGatewayTransport)
{
keyAccepted = FreeRDP_GatewayAcceptedCert;
keyLength = FreeRDP_GatewayAcceptedCertLength;
}
else if (is_redirected(tls))
{
keyAccepted = FreeRDP_RedirectionAcceptedCert;
keyLength = FreeRDP_RedirectionAcceptedCertLength;
}
const char* AcceptedKey = freerdp_settings_get_string(settings, keyAccepted);
const UINT32 AcceptedKeyLength = freerdp_settings_get_uint32(settings, keyLength);
if ((AcceptedKeyLength > 0) && AcceptedKey)
{
BOOL accepted = FALSE;
size_t pemLength = 0;
char* pem = freerdp_certificate_get_pem_ex(cert, &pemLength, FALSE);
if (pem && (AcceptedKeyLength == pemLength))
{
if (memcmp(AcceptedKey, pem, AcceptedKeyLength) == 0)
accepted = TRUE;
}
free(pem);
if (accepted)
return TRUE;
}
freerdp_settings_set_string(settings, keyAccepted, NULL);
freerdp_settings_set_uint32(settings, keyLength, 0);
return FALSE;
}
static BOOL compare_fingerprint(const char* fp, const char* hash, const rdpCertificate* cert,
BOOL separator)
{
BOOL equal = 0;
char* strhash = NULL;
WINPR_ASSERT(fp);
WINPR_ASSERT(hash);
WINPR_ASSERT(cert);
strhash = freerdp_certificate_get_fingerprint_by_hash_ex(cert, hash, separator);
if (!strhash)
return FALSE;
equal = (_stricmp(strhash, fp) == 0);
free(strhash);
return equal;
}
static BOOL compare_fingerprint_all(const char* fp, const char* hash, const rdpCertificate* cert)
{
WINPR_ASSERT(fp);
WINPR_ASSERT(hash);
WINPR_ASSERT(cert);
if (compare_fingerprint(fp, hash, cert, FALSE))
return TRUE;
if (compare_fingerprint(fp, hash, cert, TRUE))
return TRUE;
return FALSE;
}
static BOOL is_accepted_fingerprint(const rdpCertificate* cert,
const char* CertificateAcceptedFingerprints)
{
WINPR_ASSERT(cert);
BOOL rc = FALSE;
if (CertificateAcceptedFingerprints)
{
char* context = NULL;
char* copy = _strdup(CertificateAcceptedFingerprints);
char* cur = strtok_s(copy, ",", &context);
while (cur)
{
char* subcontext = NULL;
const char* h = strtok_s(cur, ":", &subcontext);
const char* fp = NULL;
if (!h)
goto next;
fp = h + strlen(h) + 1;
if (!fp)
goto next;
if (compare_fingerprint_all(fp, h, cert))
{
rc = TRUE;
break;
}
next:
cur = strtok_s(NULL, ",", &context);
}
free(copy);
}
return rc;
}
static BOOL accept_cert(rdpTls* tls, const rdpCertificate* cert)
{
WINPR_ASSERT(tls);
WINPR_ASSERT(tls->context);
WINPR_ASSERT(cert);
FreeRDP_Settings_Keys_String id = FreeRDP_AcceptedCert;
FreeRDP_Settings_Keys_UInt32 lid = FreeRDP_AcceptedCertLength;
rdpSettings* settings = tls->context->settings;
WINPR_ASSERT(settings);
if (tls->isGatewayTransport)
{
id = FreeRDP_GatewayAcceptedCert;
lid = FreeRDP_GatewayAcceptedCertLength;
}
else if (is_redirected(tls))
{
id = FreeRDP_RedirectionAcceptedCert;
lid = FreeRDP_RedirectionAcceptedCertLength;
}
size_t pemLength = 0;
char* pem = freerdp_certificate_get_pem_ex(cert, &pemLength, FALSE);
BOOL rc = FALSE;
if (freerdp_settings_set_string_len(settings, id, pem, pemLength))
rc = freerdp_settings_set_uint32(settings, lid, pemLength);
free(pem);
return rc;
}
static BOOL tls_extract_full_pem(const rdpCertificate* cert, BYTE** PublicKey,
size_t* PublicKeyLength)
{
if (!cert || !PublicKey)
return FALSE;
*PublicKey = (BYTE*)freerdp_certificate_get_pem(cert, PublicKeyLength);
return *PublicKey != NULL;
}
int tls_verify_certificate(rdpTls* tls, const rdpCertificate* cert, const char* hostname,
UINT16 port)
{
int match = 0;
size_t length = 0;
BOOL certificate_status = 0;
char* common_name = NULL;
size_t common_name_length = 0;
char** dns_names = 0;
size_t dns_names_count = 0;
size_t* dns_names_lengths = NULL;
int verification_status = -1;
BOOL hostname_match = FALSE;
rdpCertificateData* certificate_data = NULL;
BYTE* pemCert = NULL;
DWORD flags = VERIFY_CERT_FLAG_NONE;
freerdp* instance = NULL;
WINPR_ASSERT(tls);
WINPR_ASSERT(tls->context->settings);
instance = (freerdp*)tls->context->settings->instance;
WINPR_ASSERT(instance);
if (freerdp_shall_disconnect_context(instance->context))
return -1;
if (!tls_extract_full_pem(cert, &pemCert, &length))
goto end;
/* Check, if we already accepted this key. */
if (is_accepted(tls, cert))
{
verification_status = 1;
goto end;
}
if (is_accepted_fingerprint(cert, tls->context->settings->CertificateAcceptedFingerprints))
{
verification_status = 1;
goto end;
}
if (tls->isGatewayTransport || is_redirected(tls))
flags |= VERIFY_CERT_FLAG_LEGACY;
if (tls->isGatewayTransport)
flags |= VERIFY_CERT_FLAG_GATEWAY;
if (is_redirected(tls))
flags |= VERIFY_CERT_FLAG_REDIRECT;
/* Certificate management is done by the application */
if (tls->context->settings->ExternalCertificateManagement)
{
if (instance->VerifyX509Certificate)
verification_status =
instance->VerifyX509Certificate(instance, pemCert, length, hostname, port, flags);
else
WLog_ERR(TAG, "No VerifyX509Certificate callback registered!");
if (verification_status > 0)
accept_cert(tls, cert);
else if (verification_status < 0)
{
WLog_ERR(TAG, "VerifyX509Certificate failed: (length = %" PRIuz ") status: [%d] %s",
length, verification_status, pemCert);
goto end;
}
}
/* ignore certificate verification if user explicitly required it (discouraged) */
else if (tls->context->settings->IgnoreCertificate)
verification_status = 1; /* success! */
else if (!tls->isGatewayTransport && (tls->context->settings->AuthenticationLevel == 0))
verification_status = 1; /* success! */
else
{
/* if user explicitly specified a certificate name, use it instead of the hostname */
if (!tls->isGatewayTransport && tls->context->settings->CertificateName)
hostname = tls->context->settings->CertificateName;
/* attempt verification using OpenSSL and the ~/.freerdp/certs certificate store */
certificate_status = freerdp_certificate_verify(
cert, freerdp_certificate_store_get_certs_path(tls->certificate_store));
/* verify certificate name match */
certificate_data = freerdp_certificate_data_new(hostname, port, cert);
if (!certificate_data)
goto end;
/* extra common name and alternative names */
common_name = freerdp_certificate_get_common_name(cert, &common_name_length);
dns_names = freerdp_certificate_get_dns_names(cert, &dns_names_count, &dns_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 (dns_names)
{
for (size_t index = 0; index < dns_names_count; index++)
{
if (tls_match_hostname(dns_names[index], dns_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)
verification_status = 1; /* success! */
if (!hostname_match)
flags |= VERIFY_CERT_FLAG_MISMATCH;
/* verification could not succeed with OpenSSL, use known_hosts file and prompt user for
* manual verification */
if (!certificate_status || !hostname_match)
{
DWORD accept_certificate = 0;
size_t pem_length = 0;
char* issuer = freerdp_certificate_get_issuer(cert);
char* subject = freerdp_certificate_get_subject(cert);
char* pem = freerdp_certificate_get_pem(cert, &pem_length);
if (!pem)
goto end;
/* search for matching entry in known_hosts file */
match =
freerdp_certificate_store_contains_data(tls->certificate_store, certificate_data);
if (match == 1)
{
/* no entry was found in known_hosts file, prompt user for manual verification
*/
if (!hostname_match)
tls_print_certificate_name_mismatch_error(hostname, port, common_name,
dns_names, dns_names_count);
{
char* efp = freerdp_certificate_get_fingerprint(cert);
tls_print_new_certificate_warn(tls->certificate_store, hostname, port, efp);
free(efp);
}
/* Automatically accept certificate on first use */
if (tls->context->settings->AutoAcceptCertificate)
{
WLog_INFO(TAG, "No certificate stored, automatically accepting.");
accept_certificate = 1;
}
else if (tls->context->settings->AutoDenyCertificate)
{
WLog_INFO(TAG, "No certificate stored, automatically denying.");
accept_certificate = 0;
}
else if (instance->VerifyX509Certificate)
{
int rc = instance->VerifyX509Certificate(instance, pemCert, pem_length,
hostname, port, flags);
if (rc == 1)
accept_certificate = 1;
else if (rc > 1)
accept_certificate = 2;
else
accept_certificate = 0;
}
else if (instance->VerifyCertificateEx)
{
const BOOL use_pem = freerdp_settings_get_bool(
tls->context->settings, FreeRDP_CertificateCallbackPreferPEM);
char* fp = NULL;
DWORD cflags = flags;
if (use_pem)
{
cflags |= VERIFY_CERT_FLAG_FP_IS_PEM;
fp = pem;
}
else
fp = freerdp_certificate_get_fingerprint(cert);
accept_certificate = instance->VerifyCertificateEx(
instance, hostname, port, common_name, subject, issuer, fp, cflags);
if (!use_pem)
free(fp);
}
#if defined(WITH_FREERDP_DEPRECATED)
else if (instance->VerifyCertificate)
{
char* fp = freerdp_certificate_get_fingerprint(cert);
WLog_WARN(TAG, "The VerifyCertificate callback is deprecated, migrate your "
"application to VerifyCertificateEx");
accept_certificate = instance->VerifyCertificate(instance, common_name, subject,
issuer, fp, !hostname_match);
free(fp);
}
#endif
}
else if (match == -1)
{
rdpCertificateData* stored_data =
freerdp_certificate_store_load_data(tls->certificate_store, hostname, port);
/* entry was found in known_hosts file, but fingerprint does not match. ask user
* to use it */
{
char* efp = freerdp_certificate_get_fingerprint(cert);
tls_print_certificate_error(tls->certificate_store, stored_data, hostname, port,
efp);
free(efp);
}
if (!stored_data)
WLog_WARN(TAG, "Failed to get certificate entry for %s:%" PRIu16 "", hostname,
port);
if (tls->context->settings->AutoDenyCertificate)
{
WLog_INFO(TAG, "No certificate stored, automatically denying.");
accept_certificate = 0;
}
else if (instance->VerifyX509Certificate)
{
const int rc =
instance->VerifyX509Certificate(instance, pemCert, pem_length, hostname,
port, flags | VERIFY_CERT_FLAG_CHANGED);
if (rc == 1)
accept_certificate = 1;
else if (rc > 1)
accept_certificate = 2;
else
accept_certificate = 0;
}
else if (instance->VerifyChangedCertificateEx)
{
DWORD cflags = flags | VERIFY_CERT_FLAG_CHANGED;
const char* old_subject = freerdp_certificate_data_get_subject(stored_data);
const char* old_issuer = freerdp_certificate_data_get_issuer(stored_data);
const char* old_fp = freerdp_certificate_data_get_fingerprint(stored_data);
const char* old_pem = freerdp_certificate_data_get_pem(stored_data);
const BOOL fpIsAllocated =
!old_pem ||
!freerdp_settings_get_bool(tls->context->settings,
FreeRDP_CertificateCallbackPreferPEM);
char* fp = NULL;
if (!fpIsAllocated)
{
cflags |= VERIFY_CERT_FLAG_FP_IS_PEM;
fp = pem;
old_fp = old_pem;
}
else
{
fp = freerdp_certificate_get_fingerprint(cert);
}
accept_certificate = instance->VerifyChangedCertificateEx(
instance, hostname, port, common_name, subject, issuer, fp, old_subject,
old_issuer, old_fp, cflags);
if (fpIsAllocated)
free(fp);
}
#if defined(WITH_FREERDP_DEPRECATED)
else if (instance->VerifyChangedCertificate)
{
char* fp = freerdp_certificate_get_fingerprint(cert);
const char* old_subject = freerdp_certificate_data_get_subject(stored_data);
const char* old_issuer = freerdp_certificate_data_get_issuer(stored_data);
const char* old_fingerprint =
freerdp_certificate_data_get_fingerprint(stored_data);
WLog_WARN(TAG, "The VerifyChangedCertificate callback is deprecated, migrate "
"your application to VerifyChangedCertificateEx");
accept_certificate = instance->VerifyChangedCertificate(
instance, common_name, subject, issuer, fp, old_subject, old_issuer,
old_fingerprint);
free(fp);
}
#endif
freerdp_certificate_data_free(stored_data);
}
else if (match == 0)
accept_certificate = 2; /* success! */
/* Save certificate or do a simple accept / reject */
switch (accept_certificate)
{
case 1:
/* user accepted certificate, add entry in known_hosts file */
verification_status = freerdp_certificate_store_save_data(
tls->certificate_store, certificate_data)
? 1
: -1;
break;
case 2:
/* user did accept temporaty, do not add to known hosts file */
verification_status = 1;
break;
default:
/* user did not accept, abort and do not add entry in known_hosts file */
verification_status = -1; /* failure! */
break;
}
free(issuer);
free(subject);
free(pem);
}
if (verification_status > 0)
accept_cert(tls, cert);
}
end:
freerdp_certificate_data_free(certificate_data);
free(common_name);
freerdp_certificate_free_dns_names(dns_names_count, dns_names_lengths, dns_names);
free(pemCert);
return verification_status;
}
void tls_print_new_certificate_warn(rdpCertificateStore* store, const char* hostname, UINT16 port,
const char* fingerprint)
{
char* path = freerdp_certificate_store_get_cert_path(store, hostname, port);
WLog_ERR(TAG, "The host key for %s:%" PRIu16 " has changed", hostname, port);
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.", path);
WLog_ERR(TAG, "Host key for %s has changed and you have requested strict checking.", hostname);
WLog_ERR(TAG, "Host key verification failed.");
free(path);
}
void tls_print_certificate_error(rdpCertificateStore* store, rdpCertificateData* stored_data,
const char* hostname, UINT16 port, const char* fingerprint)
{
char* path = freerdp_certificate_store_get_cert_path(store, hostname, port);
WLog_ERR(TAG, "New host key for %s:%" PRIu16, hostname, port);
WLog_ERR(TAG, "@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
WLog_ERR(TAG, "@ WARNING: NEW HOST IDENTIFICATION! @");
WLog_ERR(TAG, "@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
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.", path);
free(path);
}
void tls_print_certificate_name_mismatch_error(const char* hostname, UINT16 port,
const char* common_name, char** alt_names,
size_t alt_names_count)
{
WINPR_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:%" PRIu16 ") ", hostname, port);
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)
{
WINPR_ASSERT(NULL != alt_names);
WLog_ERR(TAG, "Alternative names:");
for (size_t index = 0; index < alt_names_count; index++)
{
WINPR_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* freerdp_tls_new(rdpContext* context)
{
rdpTls* tls = NULL;
tls = (rdpTls*)calloc(1, sizeof(rdpTls));
if (!tls)
return NULL;
tls->context = context;
if (!freerdp_settings_get_bool(tls->context->settings, FreeRDP_ServerMode))
{
tls->certificate_store = freerdp_certificate_store_new(tls->context->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 freerdp_tls_free(rdpTls* tls)
{
if (!tls)
return;
tls_reset(tls);
if (tls->certificate_store)
{
freerdp_certificate_store_free(tls->certificate_store);
tls->certificate_store = NULL;
}
free(tls);
}
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