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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#include "lecmaccalculator_p.h"
#include "bluez/bluez_data_p.h"
#include <QtCore/qbytearray.h>
#include <QtCore/qloggingcategory.h>
#include <QtCore/private/qcore_unix_p.h>
#include <cstring>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#ifdef CONFIG_LINUX_CRYPTO_API
#include <linux/if_alg.h>
#endif
QT_BEGIN_NAMESPACE
Q_DECLARE_LOGGING_CATEGORY(QT_BT_BLUEZ)
LeCmacCalculator::LeCmacCalculator()
{
#ifdef CONFIG_LINUX_CRYPTO_API
m_baseSocket = socket(AF_ALG, SOCK_SEQPACKET, 0);
if (m_baseSocket == -1) {
qCWarning(QT_BT_BLUEZ) << "failed to create first level crypto socket:"
<< strerror(errno);
return;
}
sockaddr_alg sa;
using namespace std;
memset(&sa, 0, sizeof sa);
sa.salg_family = AF_ALG;
strcpy(reinterpret_cast<char *>(sa.salg_type), "hash");
strcpy(reinterpret_cast<char *>(sa.salg_name), "cmac(aes)");
if (::bind(m_baseSocket, reinterpret_cast<sockaddr *>(&sa), sizeof sa) == -1) {
qCWarning(QT_BT_BLUEZ) << "bind() failed for crypto socket:" << strerror(errno);
return;
}
#else // CONFIG_LINUX_CRYPTO_API
qCWarning(QT_BT_BLUEZ) << "Linux crypto API not present, CMAC verification will fail.";
#endif
}
LeCmacCalculator::~LeCmacCalculator()
{
if (m_baseSocket != -1)
close(m_baseSocket);
}
QByteArray LeCmacCalculator::createFullMessage(const QByteArray &message, quint32 signCounter)
{
// Spec v4.2, Vol 3, Part H, 2.4.5
QByteArray fullMessage = message;
fullMessage.resize(fullMessage.size() + sizeof signCounter);
putBtData(signCounter, fullMessage.data() + message.size());
return fullMessage;
}
quint64 LeCmacCalculator::calculateMac(const QByteArray &message, QUuid::Id128Bytes csrk) const
{
#ifdef CONFIG_LINUX_CRYPTO_API
if (m_baseSocket == -1)
return false;
QUuid::Id128Bytes csrkMsb;
std::reverse_copy(std::begin(csrk.data), std::end(csrk.data), std::begin(csrkMsb.data));
qCDebug(QT_BT_BLUEZ) << "CSRK (MSB):" << QByteArray(reinterpret_cast<char *>(csrkMsb.data),
sizeof csrkMsb).toHex();
if (setsockopt(m_baseSocket, 279 /* SOL_ALG */, ALG_SET_KEY, csrkMsb.data, sizeof csrkMsb) == -1) {
qCWarning(QT_BT_BLUEZ) << "setsockopt() failed for crypto socket:" << strerror(errno);
return 0;
}
class SocketWrapper
{
public:
SocketWrapper(int socket) : m_socket(socket) {}
~SocketWrapper() {
if (m_socket != -1)
close(m_socket);
}
int value() const { return m_socket; }
private:
int m_socket;
};
SocketWrapper cryptoSocket(accept(m_baseSocket, nullptr, nullptr));
if (cryptoSocket.value() == -1) {
qCWarning(QT_BT_BLUEZ) << "accept() failed for crypto socket:" << strerror(errno);
return 0;
}
QByteArray messageSwapped(message.size(), Qt::Uninitialized);
std::reverse_copy(message.begin(), message.end(), messageSwapped.begin());
qint64 totalBytesWritten = 0;
do {
const qint64 bytesWritten = qt_safe_write(cryptoSocket.value(),
messageSwapped.constData() + totalBytesWritten,
messageSwapped.size() - totalBytesWritten);
if (bytesWritten == -1) {
qCWarning(QT_BT_BLUEZ) << "writing to crypto socket failed:" << strerror(errno);
return 0;
}
totalBytesWritten += bytesWritten;
} while (totalBytesWritten < messageSwapped.size());
quint64 mac;
quint8 * const macPtr = reinterpret_cast<quint8 *>(&mac);
qint64 totalBytesRead = 0;
do {
const qint64 bytesRead = qt_safe_read(cryptoSocket.value(), macPtr + totalBytesRead,
sizeof mac - totalBytesRead);
if (bytesRead == -1) {
qCWarning(QT_BT_BLUEZ) << "reading from crypto socket failed:" << strerror(errno);
return 0;
}
totalBytesRead += bytesRead;
} while (totalBytesRead < qint64(sizeof mac));
return qFromBigEndian(mac);
#else // CONFIG_LINUX_CRYPTO_API
Q_UNUSED(message);
Q_UNUSED(csrk);
qCWarning(QT_BT_BLUEZ) << "CMAC calculation failed due to missing Linux crypto API.";
return 0;
#endif
}
bool LeCmacCalculator::verify(const QByteArray &message, QUuid::Id128Bytes csrk,
quint64 expectedMac) const
{
#ifdef CONFIG_LINUX_CRYPTO_API
const quint64 actualMac = calculateMac(message, csrk);
if (actualMac != expectedMac) {
qCWarning(QT_BT_BLUEZ) << Qt::hex << "signature verification failed: calculated mac:"
<< actualMac << "expected mac:" << expectedMac;
return false;
}
return true;
#else // CONFIG_LINUX_CRYPTO_API
Q_UNUSED(message);
Q_UNUSED(csrk);
Q_UNUSED(expectedMac);
qCWarning(QT_BT_BLUEZ) << "CMAC verification failed due to missing Linux crypto API.";
return false;
#endif
}
QT_END_NAMESPACE
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