/* * barrier -- mouse and keyboard sharing utility * Copyright (C) 2015-2016 Symless Ltd. * * This package is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * found in the file LICENSE that should have accompanied this file. * * This package 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 program. If not, see . */ #include "SecureSocket.h" #include "SecureUtils.h" #include "net/TSocketMultiplexerMethodJob.h" #include "base/TMethodEventJob.h" #include "net/TCPSocket.h" #include "mt/Lock.h" #include "arch/XArch.h" #include "base/Log.h" #include "base/String.h" #include "common/DataDirectories.h" #include "io/filesystem.h" #include "net/FingerprintDatabase.h" #include #include #include #include #include #include #include // // SecureSocket // #define MAX_ERROR_SIZE 65535 static const std::size_t MAX_INPUT_BUFFER_SIZE = 1024 * 1024; static const float s_retryDelay = 0.01f; enum { kMsgSize = 128 }; struct Ssl { SSL_CTX* m_context; SSL* m_ssl; }; SecureSocket::SecureSocket(IEventQueue* events, SocketMultiplexer* socketMultiplexer, IArchNetwork::EAddressFamily family, ConnectionSecurityLevel security_level) : TCPSocket(events, socketMultiplexer, family), m_ssl(nullptr), m_secureReady(false), m_fatal(false), security_level_{security_level} { } SecureSocket::SecureSocket(IEventQueue* events, SocketMultiplexer* socketMultiplexer, ArchSocket socket, ConnectionSecurityLevel security_level) : TCPSocket(events, socketMultiplexer, socket), m_ssl(nullptr), m_secureReady(false), m_fatal(false), security_level_{security_level} { } SecureSocket::~SecureSocket() { isFatal(true); // take socket from multiplexer ASAP otherwise the race condition // could cause events to get called on a dead object. TCPSocket // will do this, too, but the double-call is harmless removeJob(); freeSSLResources(); // removing sleep() because I have no idea why you would want to do it // ... smells of trying to cover up a bug you don't understand //ARCH->sleep(1); delete m_ssl; } void SecureSocket::close() { isFatal(true); freeSSLResources(); TCPSocket::close(); } void SecureSocket::freeSSLResources() { std::lock_guard ssl_lock{ssl_mutex_}; if (m_ssl->m_ssl != NULL) { SSL_shutdown(m_ssl->m_ssl); SSL_free(m_ssl->m_ssl); m_ssl->m_ssl = NULL; } if (m_ssl->m_context != NULL) { SSL_CTX_free(m_ssl->m_context); m_ssl->m_context = NULL; } } void SecureSocket::connect(const NetworkAddress& addr) { m_events->adoptHandler(m_events->forIDataSocket().connected(), getEventTarget(), new TMethodEventJob(this, &SecureSocket::handleTCPConnected)); TCPSocket::connect(addr); } std::unique_ptr SecureSocket::newJob() { // after TCP connection is established, SecureSocket will pick up // connected event and do secureConnect if (m_connected && !m_secureReady) { return {}; } return TCPSocket::newJob(); } void SecureSocket::secureConnect() { setJob(std::make_unique([this](auto j, auto r, auto w, auto e) { return serviceConnect(j, r, w, e); }, getSocket(), isReadable(), isWritable())); } void SecureSocket::secureAccept() { setJob(std::make_unique([this](auto j, auto r, auto w, auto e) { return serviceAccept(j, r, w, e); }, getSocket(), isReadable(), isWritable())); } TCPSocket::EJobResult SecureSocket::doRead() { UInt8 buffer[4096]; memset(buffer, 0, sizeof(buffer)); int bytesRead = 0; int status = 0; if (isSecureReady()) { status = secureRead(buffer, sizeof(buffer), bytesRead); if (status < 0) { return kBreak; } else if (status == 0) { return kNew; } } else { return kRetry; } if (bytesRead > 0) { bool wasEmpty = (m_inputBuffer.getSize() == 0); // slurp up as much as possible do { m_inputBuffer.write(buffer, bytesRead); if (m_inputBuffer.getSize() > MAX_INPUT_BUFFER_SIZE) { break; } status = secureRead(buffer, sizeof(buffer), bytesRead); if (status < 0) { return kBreak; } } while (bytesRead > 0 || status > 0); // send input ready if input buffer was empty if (wasEmpty) { sendEvent(m_events->forIStream().inputReady()); } } else { // remote write end of stream hungup. our input side // has therefore shutdown but don't flush our buffer // since there's still data to be read. sendEvent(m_events->forIStream().inputShutdown()); if (!m_writable && m_inputBuffer.getSize() == 0) { sendEvent(m_events->forISocket().disconnected()); m_connected = false; } m_readable = false; return kNew; } return kRetry; } TCPSocket::EJobResult SecureSocket::doWrite() { // write data int bufferSize = 0; int bytesWrote = 0; int status = 0; if (!isSecureReady()) return kRetry; if (do_write_retry_) { bufferSize = do_write_retry_size_; } else { bufferSize = m_outputBuffer.getSize(); if (bufferSize > do_write_retry_buffer_size_) { do_write_retry_buffer_.reset(new char[bufferSize]); do_write_retry_buffer_size_ = bufferSize; } if (bufferSize > 0) { std::memcpy(do_write_retry_buffer_.get(), m_outputBuffer.peek(bufferSize), bufferSize); } } if (bufferSize == 0) { return kRetry; } status = secureWrite(do_write_retry_buffer_.get(), bufferSize, bytesWrote); if (status > 0) { do_write_retry_ = false; } else if (status < 0) { return kBreak; } else if (status == 0) { do_write_retry_ = true; do_write_retry_size_ = bufferSize; return kNew; } if (bytesWrote > 0) { discardWrittenData(bytesWrote); return kNew; } return kRetry; } int SecureSocket::secureRead(void* buffer, int size, int& read) { std::lock_guard ssl_lock{ssl_mutex_}; if (m_ssl->m_ssl != NULL) { LOG((CLOG_DEBUG2 "reading secure socket")); read = SSL_read(m_ssl->m_ssl, buffer, size); // Check result will cleanup the connection in the case of a fatal checkResult(read, secure_read_retry_); if (secure_read_retry_) { return 0; } if (isFatal()) { return -1; } } // According to SSL spec, the number of bytes read must not be negative and // not have an error code from SSL_get_error(). If this happens, it is // itself an error. Let the parent handle the case return read; } int SecureSocket::secureWrite(const void* buffer, int size, int& wrote) { std::lock_guard ssl_lock{ssl_mutex_}; if (m_ssl->m_ssl != NULL) { LOG((CLOG_DEBUG2 "writing secure socket:%p", this)); wrote = SSL_write(m_ssl->m_ssl, buffer, size); // Check result will cleanup the connection in the case of a fatal checkResult(wrote, secure_write_retry_); if (secure_write_retry_) { return 0; } if (isFatal()) { return -1; } } // According to SSL spec, r must not be negative and not have an error code // from SSL_get_error(). If this happens, it is itself an error. Let the // parent handle the case return wrote; } bool SecureSocket::isSecureReady() { return m_secureReady; } void SecureSocket::initSsl(bool server) { std::lock_guard ssl_lock{ssl_mutex_}; m_ssl = new Ssl(); m_ssl->m_context = NULL; m_ssl->m_ssl = NULL; initContext(server); } bool SecureSocket::load_certificates(const barrier::fs::path& path) { std::lock_guard ssl_lock{ssl_mutex_}; if (path.empty()) { showError("ssl certificate is not specified"); return false; } else { if (!barrier::fs::is_regular_file(path)) { showError("ssl certificate doesn't exist: " + path.u8string()); return false; } } int r = 0; r = SSL_CTX_use_certificate_file(m_ssl->m_context, path.u8string().c_str(), SSL_FILETYPE_PEM); if (r <= 0) { showError("could not use ssl certificate: " + path.u8string()); return false; } r = SSL_CTX_use_PrivateKey_file(m_ssl->m_context, path.u8string().c_str(), SSL_FILETYPE_PEM); if (r <= 0) { showError("could not use ssl private key: " + path.u8string()); return false; } r = SSL_CTX_check_private_key(m_ssl->m_context); if (!r) { showError("could not verify ssl private key: " + path.u8string()); return false; } return true; } static int cert_verify_ignore_callback(X509_STORE_CTX*, void*) { return 1; } void SecureSocket::initContext(bool server) { // ssl_mutex_ is assumed to be acquired SSL_library_init(); const SSL_METHOD* method; // load & register all cryptos, etc. OpenSSL_add_all_algorithms(); // load all error messages SSL_load_error_strings(); if (CLOG->getFilter() >= kINFO) { showSecureLibInfo(); } // SSLv23_method uses TLSv1, with the ability to fall back to SSLv3 if (server) { method = SSLv23_server_method(); } else { method = SSLv23_client_method(); } // create new context from method SSL_METHOD* m = const_cast(method); m_ssl->m_context = SSL_CTX_new(m); // drop SSLv3 support SSL_CTX_set_options(m_ssl->m_context, SSL_OP_NO_SSLv3); if (m_ssl->m_context == NULL) { showError(""); } if (security_level_ == ConnectionSecurityLevel::ENCRYPTED_AUTHENTICATED) { // We want to ask for peer certificate, but not verify it. If we don't ask for peer // certificate, e.g. client won't send it. SSL_CTX_set_verify(m_ssl->m_context, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT, nullptr); SSL_CTX_set_cert_verify_callback(m_ssl->m_context, cert_verify_ignore_callback, nullptr); } } void SecureSocket::createSSL() { // ssl_mutex_ is assumed to be acquired // I assume just one instance is needed // get new SSL state with context if (m_ssl->m_ssl == NULL) { assert(m_ssl->m_context != NULL); m_ssl->m_ssl = SSL_new(m_ssl->m_context); } } int SecureSocket::secureAccept(int socket) { std::lock_guard ssl_lock{ssl_mutex_}; createSSL(); // set connection socket to SSL state SSL_set_fd(m_ssl->m_ssl, socket); LOG((CLOG_DEBUG2 "accepting secure socket")); int r = SSL_accept(m_ssl->m_ssl); checkResult(r, secure_accept_retry_); if (isFatal()) { // tell user and sleep so the socket isn't hammered. LOG((CLOG_ERR "failed to accept secure socket")); LOG((CLOG_INFO "client connection may not be secure")); m_secureReady = false; ARCH->sleep(1); secure_accept_retry_ = 0; return -1; // Failed, error out } // If not fatal and no retry, state is good if (secure_accept_retry_ == 0) { if (security_level_ == ConnectionSecurityLevel::ENCRYPTED_AUTHENTICATED) { if (verify_cert_fingerprint( barrier::DataDirectories::trusted_clients_ssl_fingerprints_path())) { LOG((CLOG_INFO "accepted secure socket")); if (!ensure_peer_certificate()) { secure_accept_retry_ = 0; disconnect(); return -1;// Cert fail, error } } else { LOG((CLOG_ERR "failed to verify server certificate fingerprint")); secure_accept_retry_ = 0; disconnect(); return -1; // Fingerprint failed, error } } m_secureReady = true; LOG((CLOG_INFO "accepted secure socket")); if (CLOG->getFilter() >= kDEBUG1) { showSecureCipherInfo(); } showSecureConnectInfo(); return 1; } // If not fatal and retry is set, not ready, and return retry if (secure_accept_retry_ > 0) { LOG((CLOG_DEBUG2 "retry accepting secure socket")); m_secureReady = false; ARCH->sleep(s_retryDelay); return 0; } // no good state exists here LOG((CLOG_ERR "unexpected state attempting to accept connection")); return -1; } int SecureSocket::secureConnect(int socket) { // note that load_certificates acquires ssl_mutex_ if (!load_certificates(barrier::DataDirectories::ssl_certificate_path())) { LOG((CLOG_ERR "could not load client certificates")); // FIXME: this is fatal error, but we current don't disconnect because whole logic in this // function needs to be cleaned up } std::lock_guard ssl_lock{ssl_mutex_}; createSSL(); // attach the socket descriptor SSL_set_fd(m_ssl->m_ssl, socket); LOG((CLOG_DEBUG2 "connecting secure socket")); int r = SSL_connect(m_ssl->m_ssl); checkResult(r, secure_connect_retry_); if (isFatal()) { LOG((CLOG_ERR "failed to connect secure socket")); secure_connect_retry_ = 0; return -1; } // If we should retry, not ready and return 0 if (secure_connect_retry_ > 0) { LOG((CLOG_DEBUG2 "retry connect secure socket")); m_secureReady = false; ARCH->sleep(s_retryDelay); return 0; } secure_connect_retry_ = 0; // No error, set ready, process and return ok m_secureReady = true; if (verify_cert_fingerprint(barrier::DataDirectories::trusted_servers_ssl_fingerprints_path())) { LOG((CLOG_INFO "connected to secure socket")); if (!ensure_peer_certificate()) { disconnect(); return -1;// Cert fail, error } } else { LOG((CLOG_ERR "failed to verify server certificate fingerprint")); disconnect(); return -1; // Fingerprint failed, error } LOG((CLOG_DEBUG2 "connected secure socket")); if (CLOG->getFilter() >= kDEBUG1) { showSecureCipherInfo(); } showSecureConnectInfo(); return 1; } bool SecureSocket::ensure_peer_certificate() { // ssl_mutex_ is assumed to be acquired X509* cert; char* line; // get the server's certificate cert = SSL_get_peer_certificate(m_ssl->m_ssl); if (cert != NULL) { line = X509_NAME_oneline(X509_get_subject_name(cert), 0, 0); LOG((CLOG_INFO "peer ssl certificate info: %s", line)); OPENSSL_free(line); X509_free(cert); } else { showError("peer has no ssl certificate"); return false; } return true; } void SecureSocket::checkResult(int status, int& retry) { // ssl_mutex_ is assumed to be acquired // ssl errors are a little quirky. the "want" errors are normal and // should result in a retry. int errorCode = SSL_get_error(m_ssl->m_ssl, status); switch (errorCode) { case SSL_ERROR_NONE: retry = 0; // operation completed break; case SSL_ERROR_ZERO_RETURN: // connection closed isFatal(true); LOG((CLOG_DEBUG "ssl connection closed")); break; case SSL_ERROR_WANT_READ: retry++; LOG((CLOG_DEBUG2 "want to read, error=%d, attempt=%d", errorCode, retry)); break; case SSL_ERROR_WANT_WRITE: // Need to make sure the socket is known to be writable so the impending // select action actually triggers on a write. This isn't necessary for // m_readable because the socket logic is always readable m_writable = true; retry++; LOG((CLOG_DEBUG2 "want to write, error=%d, attempt=%d", errorCode, retry)); break; case SSL_ERROR_WANT_CONNECT: retry++; LOG((CLOG_DEBUG2 "want to connect, error=%d, attempt=%d", errorCode, retry)); break; case SSL_ERROR_WANT_ACCEPT: retry++; LOG((CLOG_DEBUG2 "want to accept, error=%d, attempt=%d", errorCode, retry)); break; case SSL_ERROR_SYSCALL: LOG((CLOG_ERR "ssl error occurred (system call failure)")); if (ERR_peek_error() == 0) { if (status == 0) { LOG((CLOG_ERR "eof violates ssl protocol")); } else if (status == -1) { // underlying socket I/O reproted an error try { ARCH->throwErrorOnSocket(getSocket()); } catch (XArchNetwork& e) { LOG((CLOG_ERR "%s", e.what())); } } } isFatal(true); break; case SSL_ERROR_SSL: LOG((CLOG_ERR "ssl error occurred (generic failure)")); isFatal(true); break; default: LOG((CLOG_ERR "ssl error occurred (unknown failure)")); isFatal(true); break; } if (isFatal()) { retry = 0; showError(""); disconnect(); } } void SecureSocket::showError(const std::string& reason) { if (!reason.empty()) { LOG((CLOG_ERR "%s", reason.c_str())); } std::string error = getError(); if (!error.empty()) { LOG((CLOG_ERR "%s", error.c_str())); } } std::string SecureSocket::getError() { unsigned long e = ERR_get_error(); if (e != 0) { char error[MAX_ERROR_SIZE]; ERR_error_string_n(e, error, MAX_ERROR_SIZE); return error; } else { return ""; } } void SecureSocket::disconnect() { sendEvent(getEvents()->forISocket().stopRetry()); sendEvent(getEvents()->forISocket().disconnected()); sendEvent(getEvents()->forIStream().inputShutdown()); } bool SecureSocket::verify_cert_fingerprint(const barrier::fs::path& fingerprint_db_path) { // ssl_mutex_ is assumed to be acquired // calculate received certificate fingerprint barrier::FingerprintData fingerprint_sha1, fingerprint_sha256; try { auto* cert = SSL_get_peer_certificate(m_ssl->m_ssl); fingerprint_sha1 = barrier::get_ssl_cert_fingerprint(cert, barrier::FingerprintType::SHA1); fingerprint_sha256 = barrier::get_ssl_cert_fingerprint(cert, barrier::FingerprintType::SHA256); } catch (const std::exception& e) { LOG((CLOG_ERR "%s", e.what())); return false; } // note: the GUI parses the following two lines of logs, don't change unnecessarily LOG((CLOG_NOTE "peer fingerprint (SHA1): %s (SHA256): %s", barrier::format_ssl_fingerprint(fingerprint_sha1.data).c_str(), barrier::format_ssl_fingerprint(fingerprint_sha256.data).c_str())); // Provide debug hint as to what file is being used to verify fingerprint trust LOG((CLOG_NOTE "fingerprint_db_path: %s", fingerprint_db_path.u8string().c_str())); barrier::FingerprintDatabase db; db.read(fingerprint_db_path); if (!db.fingerprints().empty()) { LOG((CLOG_NOTE "Read %d fingerprints from: %s", db.fingerprints().size(), fingerprint_db_path.u8string().c_str())); } else { LOG((CLOG_NOTE "Could not read fingerprints from: %s", fingerprint_db_path.u8string().c_str())); } if (db.is_trusted(fingerprint_sha256)) { LOG((CLOG_NOTE "Fingerprint matches trusted fingerprint")); return true; } else { LOG((CLOG_NOTE "Fingerprint does not match trusted fingerprint")); return false; } } MultiplexerJobStatus SecureSocket::serviceConnect(ISocketMultiplexerJob* job, bool read, bool write, bool error) { (void) read; Lock lock(&getMutex()); int status = 0; #ifdef SYSAPI_WIN32 status = secureConnect(static_cast(getSocket()->m_socket)); #elif SYSAPI_UNIX status = secureConnect(getSocket()->m_fd); #endif // If status < 0, error happened if (status < 0) { return {false, {}}; } // If status > 0, success if (status > 0) { sendEvent(m_events->forIDataSocket().secureConnected()); return newJobOrStopServicing(); } // Retry case return { true, std::make_unique([this](auto j, auto r, auto w, auto e) { return serviceConnect(j, r, w, e); }, getSocket(), isReadable(), isWritable()) }; } MultiplexerJobStatus SecureSocket::serviceAccept(ISocketMultiplexerJob* job, bool read, bool write, bool error) { (void) read; Lock lock(&getMutex()); int status = 0; #ifdef SYSAPI_WIN32 status = secureAccept(static_cast(getSocket()->m_socket)); #elif SYSAPI_UNIX status = secureAccept(getSocket()->m_fd); #endif // If status < 0, error happened if (status < 0) { return {false, {}}; } // If status > 0, success if (status > 0) { sendEvent(m_events->forClientListener().accepted()); return newJobOrStopServicing(); } // Retry case return { true, std::make_unique([this](auto j, auto r, auto w, auto e) { return serviceAccept(j, r, w, e); }, getSocket(), isReadable(), isWritable()) }; } void showCipherStackDesc(STACK_OF(SSL_CIPHER) * stack) { char msg[kMsgSize]; int i = 0; for ( ; i < sk_SSL_CIPHER_num(stack) ; i++) { const SSL_CIPHER * cipher = sk_SSL_CIPHER_value(stack,i); SSL_CIPHER_description(cipher, msg, kMsgSize); // Why does SSL put a newline in the description? int pos = (int)strlen(msg) - 1; if (msg[pos] == '\n') { msg[pos] = '\0'; } LOG((CLOG_DEBUG1 "%s",msg)); } } void SecureSocket::showSecureCipherInfo() { // ssl_mutex_ is assumed to be acquired STACK_OF(SSL_CIPHER) * sStack = SSL_get_ciphers(m_ssl->m_ssl); if (sStack == NULL) { LOG((CLOG_DEBUG1 "local cipher list not available")); } else { LOG((CLOG_DEBUG1 "available local ciphers:")); showCipherStackDesc(sStack); } #if OPENSSL_VERSION_NUMBER < 0x10100000L // m_ssl->m_ssl->session->ciphers is not forward compatible, // In future release of OpenSSL, it's not visible, STACK_OF(SSL_CIPHER) * cStack = m_ssl->m_ssl->session->ciphers; #else // Use SSL_get_client_ciphers() for newer versions STACK_OF(SSL_CIPHER) * cStack = SSL_get_client_ciphers(m_ssl->m_ssl); #endif if (cStack == NULL) { LOG((CLOG_DEBUG1 "remote cipher list not available")); } else { LOG((CLOG_DEBUG1 "available remote ciphers:")); showCipherStackDesc(cStack); } return; } void SecureSocket::showSecureLibInfo() { LOG((CLOG_INFO "%s",SSLeay_version(SSLEAY_VERSION))); LOG((CLOG_DEBUG1 "openSSL : %s",SSLeay_version(SSLEAY_CFLAGS))); LOG((CLOG_DEBUG1 "openSSL : %s",SSLeay_version(SSLEAY_BUILT_ON))); LOG((CLOG_DEBUG1 "openSSL : %s",SSLeay_version(SSLEAY_PLATFORM))); LOG((CLOG_DEBUG1 "%s",SSLeay_version(SSLEAY_DIR))); return; } void SecureSocket::showSecureConnectInfo() { // ssl_mutex_ is assumed to be acquired const SSL_CIPHER* cipher = SSL_get_current_cipher(m_ssl->m_ssl); if (cipher != NULL) { char msg[kMsgSize]; SSL_CIPHER_description(cipher, msg, kMsgSize); LOG((CLOG_INFO "%s", msg)); } return; } void SecureSocket::handleTCPConnected(const Event& event, void*) { if (getSocket() == nullptr) { LOG((CLOG_DEBUG "disregarding stale connect event")); return; } secureConnect(); }