Use cryptographic nonce instead of counters.

src/plugins/sfdisk/sfdiskbackend.cpp

@@ -196,7 +196,6 @@ Device* SfdiskBackend::scanDevice(const QString& deviceNode)
 
         if (checkVG.run(-1) && checkVG.exitCode() == 0)
         {
-            qDebug() << "Trying to find LVM VG";
             QList<Device *> availableDevices = scanDevices();
 
             LvmDevice::scanSystemLVM(availableDevices);

src/util/externalcommand.cpp

@@ -57,7 +57,6 @@ struct ExternalCommandPrivate
     QProcess::ProcessChannelMode processChannelMode;
 };
 
-unsigned int ExternalCommand::counter = 0;
 KAuth::ExecuteJob* ExternalCommand::m_job;
 QCA::PrivateKey* ExternalCommand::privateKey;
 QCA::Initializer* ExternalCommand::init;
@@ -144,7 +143,7 @@ bool ExternalCommand::start(int timeout)
     if (iface.isValid()) {
         QByteArray request;
 
-        request.setNum(++counter);
+        request.setNum(getNonce(iface));
         request.append(cmd.toUtf8());
         for (const auto &argument : qAsConst(d->m_Args))
             request.append(argument.toUtf8());
@@ -204,7 +203,7 @@ bool ExternalCommand::copyBlocks(CopySource& source, CopyTarget& target)
     if (iface.isValid()) {
         QByteArray request;
 
-        request.setNum(++counter);
+        request.setNum(getNonce(iface));
         request.append(source.path().toUtf8());
         request.append(QByteArray::number(source.firstByte()));
         request.append(QByteArray::number(source.length()));
@@ -411,7 +410,7 @@ void ExternalCommand::stopHelper()
     QDBusInterface iface(QStringLiteral("org.kde.kpmcore.helperinterface"), QStringLiteral("/Helper"), QStringLiteral("org.kde.kpmcore.externalcommand"), QDBusConnection::systemBus());
     if (iface.isValid()) {
         QByteArray request;
-        request.setNum(++counter);
+        request.setNum(getNonce(iface));
         QByteArray hash = QCryptographicHash::hash(request, QCryptographicHash::Sha512);
         iface.call(QStringLiteral("exit"), privateKey->signMessage(hash, QCA::EMSA3_Raw));
     }
@@ -420,6 +419,29 @@ void ExternalCommand::stopHelper()
     delete init;
 }
 
+unsigned long long ExternalCommand::getNonce(QDBusInterface& iface)
+{
+        QDBusPendingCall pcall = iface.asyncCall(QStringLiteral("getNonce"));
+        QDBusPendingCallWatcher *watcher = new QDBusPendingCallWatcher(pcall);
+        QEventLoop loop;
+        unsigned long long rval = 0;
+
+        auto exitLoop = [&] (QDBusPendingCallWatcher *watcher) {
+            loop.exit();
+
+            if (watcher->isError())
+                qWarning() << watcher->error();
+            else {
+                QDBusPendingReply<unsigned long long> reply = *watcher;
+                rval = reply;
+            }
+        };
+
+        connect(watcher, &QDBusPendingCallWatcher::finished, exitLoop);
+        loop.exec();
+        return rval;
+}
+
 void DBusThread::run()
 {
     if (!QDBusConnection::systemBus().registerService(QStringLiteral("org.kde.kpmcore.applicationinterface"))) {

src/util/externalcommand.h

@@ -37,6 +37,7 @@ namespace QCA { class PrivateKey; class Initializer; }
 class Report;
 class CopySource;
 class CopyTarget;
+class QDBusInterface;
 struct ExternalCommandPrivate;
 
 class DBusThread : public QThread
@@ -129,12 +130,13 @@ private:
 
     void onFinished(int exitCode, QProcess::ExitStatus exitStatus);
     void onReadOutput();
+    static unsigned long long getNonce(QDBusInterface& iface);
 
 private:
     std::unique_ptr<ExternalCommandPrivate> d;
 
     // KAuth stuff
-    static unsigned int counter;
+    static unsigned long long m_Nonce;
     static KAuth::ExecuteJob *m_job;
     static QCA::Initializer *init;
     static QCA::PrivateKey *privateKey;

src/util/externalcommandhelper.cpp

@@ -61,7 +61,7 @@ ActionReply ExternalCommandHelper::init(const QVariantMap& args)
     }
 
     m_publicKey = QCA::PublicKey::fromDER(args[QStringLiteral("pubkey")].toByteArray());
-    m_Counter = 0;
+    m_Nonce = m_Generator.generate();
 
     HelperSupport::progressStep(QVariantMap());
     auto timeout = [this] () {
@@ -90,6 +90,15 @@ ActionReply ExternalCommandHelper::init(const QVariantMap& args)
     return reply;
 }
 
+/** Generates cryptographic nonce
+ *  @return nonce
+*/
+unsigned long long ExternalCommandHelper::getNonce()
+{
+    m_Nonce = m_Generator.generate();
+    return m_Nonce;
+}
+
 /** Reads the given number of bytes from the sourceDevice into the given buffer.
     @param sourceDevice device or file to read from
     @param buffer buffer to store the bytes read in
@@ -151,7 +160,7 @@ bool ExternalCommandHelper::copyblocks(const QByteArray& signature, const QStrin
 {
     QByteArray request;
 
-    request.setNum(++m_Counter);
+    request.setNum(m_Nonce);
     request.append(sourceDevice.toUtf8());
     request.append(QByteArray::number(sourceFirstByte));
     request.append(QByteArray::number(sourceLength));
@@ -248,9 +257,10 @@ QVariantMap ExternalCommandHelper::start(const QByteArray& signature, const QStr
 {
     QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF-8"));
     QVariantMap reply;
+    reply[QStringLiteral("success")] = true;
 
     QByteArray request;
-    request.setNum(++m_Counter);
+    request.setNum(m_Nonce);
     request.append(command.toUtf8());
     for (const auto &argument : arguments)
         request.append(argument.toUtf8());
@@ -281,7 +291,7 @@ QVariantMap ExternalCommandHelper::start(const QByteArray& signature, const QStr
 void ExternalCommandHelper::exit(const QByteArray& signature)
 {
     QByteArray request;
-    request.setNum(++m_Counter);
+    request.setNum(m_Nonce);
     QByteArray hash = QCryptographicHash::hash(request, QCryptographicHash::Sha512);
     if (!m_publicKey.verifyMessage(hash, signature, QCA::EMSA3_Raw)) {
         qCritical() << xi18n("Invalid cryptographic signature");

src/util/externalcommandhelper.h

@@ -21,6 +21,7 @@
 #include <KAuth>
 
 #include <QEventLoop>
+#include <QRandomGenerator64>
 #include <QString>
 #include <QProcess>
 
@@ -43,6 +44,7 @@ public:
 
 public Q_SLOTS:
     ActionReply init(const QVariantMap& args);
+    Q_SCRIPTABLE unsigned long long getNonce();
     Q_SCRIPTABLE QVariantMap start(const QByteArray& signature, const QString& command, const QStringList& arguments, const QByteArray& input, const int processChannelMode);
     Q_SCRIPTABLE bool copyblocks(const QByteArray& signature, const QString& sourceDevice, const qint64 sourceFirstByte, const qint64 sourceLength, const QString& targetDevice, const qint64 targetFirstByte, const qint64 blockSize);
     Q_SCRIPTABLE void exit(const QByteArray& signature);
@@ -53,7 +55,8 @@ private:
     QEventLoop m_loop;
     QCA::Initializer initializer;
     QCA::PublicKey m_publicKey;
-    unsigned int m_Counter;
+    QRandomGenerator64 m_Generator;
+    unsigned long long m_Nonce;
     QString m_command;
     QString m_sourceDevice;
     QProcess m_cmd;