Fix passing QDBusUnixFileDescriptors over peer-to-peer connections

Passing QDBusUnixFileDescriptors over peer-to-peer connections currently
does not work, because QDBusConnectionPrivate::setPeer() does not set
this->capabilities (unlike QDBusConnectionPrivate::setConnection()
which is executed for bus connections).

Keep track of whether the connection already has been authenticated, and
once the connection does get authenticated, update this->capabilities.

Note that sending a message directly after connecting (before any
message has been received from the peer) might still fail if the message
contains a QDBusUnixFileDescriptor.

Pick-to: 5.15
Fixes: QTBUG-85396
Change-Id: Ib83213ebcd3255fb091c6faefb3618745b8d736c
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

5 files changed, 41 insertions, 12 deletions

diff --git a/src/dbus/qdbus_symbols_p.h b/src/dbus/qdbus_symbols_p.h
index 7cce0d71aa..accaa4f5ed 100644
--- a/src/dbus/qdbus_symbols_p.h
+++ b/src/dbus/qdbus_symbols_p.h
@@ -213,6 +213,8 @@ DEFINEFUNC(DBusDispatchStatus , dbus_connection_dispatch,   (DBusConnection
            (connection), return)
 DEFINEFUNC(DBusDispatchStatus , dbus_connection_get_dispatch_status, (DBusConnection             *connection),
            (connection), return)
+DEFINEFUNC(dbus_bool_t, dbus_connection_get_is_authenticated, (DBusConnection * connection),
+           (connection), return )
 DEFINEFUNC(dbus_bool_t        , dbus_connection_get_is_connected, (DBusConnection             *connection),
            (connection), return)
 DEFINEFUNC(DBusConnection*    , dbus_connection_open_private, (const char                 *address,
diff --git a/src/dbus/qdbusconnection.cpp b/src/dbus/qdbusconnection.cpp
index f690e52247..329a539e23 100644
--- a/src/dbus/qdbusconnection.cpp
+++ b/src/dbus/qdbusconnection.cpp
@@ -1119,7 +1119,7 @@ QString QDBusConnection::name() const
 */
 QDBusConnection::ConnectionCapabilities QDBusConnection::connectionCapabilities() const
 {
-    return d ? d->capabilities : ConnectionCapabilities();
+    return d ? d->connectionCapabilities() : ConnectionCapabilities();
 }
 
 /*!
diff --git a/src/dbus/qdbusconnection_p.h b/src/dbus/qdbusconnection_p.h
index d3b46153cb..84c5aee3d7 100644
--- a/src/dbus/qdbusconnection_p.h
+++ b/src/dbus/qdbusconnection_p.h
@@ -277,6 +277,8 @@ private:
 
     void _q_newConnection(QDBusConnectionPrivate *newConnection);
 
+    void handleAuthentication();
+
 protected:
     void timerEvent(QTimerEvent *e) override;
 
@@ -309,7 +311,11 @@ signals:
 
 public:
     QAtomicInt ref;
-    QDBusConnection::ConnectionCapabilities capabilities;
+    QAtomicInt capabilities;
+    QDBusConnection::ConnectionCapabilities connectionCapabilities() const
+    {
+        return (QDBusConnection::ConnectionCapabilities)capabilities.loadRelaxed();
+    }
     QString name;               // this connection's name
     QString baseService;        // this connection's base service
     QStringList serverConnectionNames;
@@ -342,6 +348,7 @@ public:
 
     bool anonymousAuthenticationAllowed;
     bool dispatchEnabled;               // protected by the dispatch lock, not the main lock
+    bool isAuthenticated;
 
 public:
     // static methods
diff --git a/src/dbus/qdbusintegrator.cpp b/src/dbus/qdbusintegrator.cpp
index 32521c85e7..07816568e5 100644
--- a/src/dbus/qdbusintegrator.cpp
+++ b/src/dbus/qdbusintegrator.cpp
@@ -526,7 +526,7 @@ qDBusSignalFilter(DBusConnection *connection, DBusMessage *message, void *data)
     if (d->mode == QDBusConnectionPrivate::InvalidMode)
         return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
 
-    QDBusMessage amsg = QDBusMessagePrivate::fromDBusMessage(message, d->capabilities);
+    QDBusMessage amsg = QDBusMessagePrivate::fromDBusMessage(message, d->connectionCapabilities());
     qDBusDebug() << d << "got message (signal):" << amsg;
 
     return d->handleMessage(amsg) ?
@@ -1028,11 +1028,15 @@ void QDBusConnectionPrivate::deliverCall(QObject *object, int /*flags*/, const Q
 extern bool qDBusInitThreads();
 
 QDBusConnectionPrivate::QDBusConnectionPrivate(QObject *p)
-    : QObject(p), ref(1), mode(InvalidMode), busService(nullptr),
+    : QObject(p),
+      ref(1),
+      mode(InvalidMode),
+      busService(nullptr),
       connection(nullptr),
       rootNode(QString(QLatin1Char('/'))),
       anonymousAuthenticationAllowed(false),
-      dispatchEnabled(true)
+      dispatchEnabled(true),
+      isAuthenticated(false)
 {
     static const bool threads = q_dbus_threads_init_default();
     if (::isDebugging == -1)
@@ -1218,6 +1222,9 @@ void QDBusConnectionPrivate::socketRead(qintptr fd)
         }
         ++it;
     }
+    if ((mode == ClientMode || mode == PeerMode) && !isAuthenticated
+        && q_dbus_connection_get_is_authenticated(connection))
+        handleAuthentication();
     doDispatch();
 }
 
@@ -1232,6 +1239,9 @@ void QDBusConnectionPrivate::socketWrite(qintptr fd)
         }
         ++it;
     }
+    if ((mode == ClientMode || mode == PeerMode) && !isAuthenticated
+        && q_dbus_connection_get_is_authenticated(connection))
+        handleAuthentication();
 }
 
 void QDBusConnectionPrivate::objectDestroyed(QObject *obj)
@@ -1274,7 +1284,8 @@ void QDBusConnectionPrivate::relaySignal(QObject *obj, const QMetaObject *mo, in
     QDBusMessagePrivate::setParametersValidated(message, true);
     message.setArguments(args);
     QDBusError error;
-    DBusMessage *msg = QDBusMessagePrivate::toDBusMessage(message, capabilities, &error);
+    DBusMessage *msg =
+            QDBusMessagePrivate::toDBusMessage(message, connectionCapabilities(), &error);
     if (!msg) {
         qWarning("QDBusConnection: Could not emit signal %s.%s: %s", qPrintable(interface), memberName.constData(),
                  qPrintable(error.message()));
@@ -1794,6 +1805,12 @@ static QDBusConnection::ConnectionCapabilities connectionCapabilies(DBusConnecti
     return result;
 }
 
+void QDBusConnectionPrivate::handleAuthentication()
+{
+    capabilities.storeRelaxed(connectionCapabilies(connection));
+    isAuthenticated = true;
+}
+
 void QDBusConnectionPrivate::setConnection(DBusConnection *dbc, const QDBusErrorInternal &error)
 {
     mode = ClientMode;
@@ -1807,7 +1824,8 @@ void QDBusConnectionPrivate::setConnection(DBusConnection *dbc, const QDBusError
     const char *service = q_dbus_bus_get_unique_name(connection);
     Q_ASSERT(service);
     baseService = QString::fromUtf8(service);
-    capabilities = connectionCapabilies(connection);
+    // bus connections are already authenticated here because q_dbus_bus_register() has been called
+    handleAuthentication();
 
     q_dbus_connection_set_exit_on_disconnect(connection, false);
     q_dbus_connection_set_watch_functions(connection, qDBusAddWatch, qDBusRemoveWatch,
@@ -1876,7 +1894,7 @@ void QDBusConnectionPrivate::processFinishedCall(QDBusPendingCallPrivate *call)
         if (q_dbus_pending_call_get_completed(call->pending)) {
             // decode the message
             DBusMessage *reply = q_dbus_pending_call_steal_reply(call->pending);
-            msg = QDBusMessagePrivate::fromDBusMessage(reply, connection->capabilities);
+            msg = QDBusMessagePrivate::fromDBusMessage(reply, connection->connectionCapabilities());
             q_dbus_message_unref(reply);
         } else {
             msg = QDBusMessage::createError(QDBusError::Disconnected, QDBusUtil::disconnectedErrorMessage());
@@ -1930,7 +1948,8 @@ bool QDBusConnectionPrivate::send(const QDBusMessage& message)
                                 // through the d_ptr->localReply link
 
     QDBusError error;
-    DBusMessage *msg = QDBusMessagePrivate::toDBusMessage(message, capabilities, &error);
+    DBusMessage *msg =
+            QDBusMessagePrivate::toDBusMessage(message, connectionCapabilities(), &error);
     if (!msg) {
         if (message.type() == QDBusMessage::MethodCallMessage)
             qWarning("QDBusConnection: error: could not send message to service \"%s\" path \"%s\" interface \"%s\" member \"%s\": %s",
@@ -2144,7 +2163,8 @@ QDBusPendingCallPrivate *QDBusConnectionPrivate::sendWithReplyAsync(const QDBusM
     }
 
     QDBusError error;
-    DBusMessage *msg = QDBusMessagePrivate::toDBusMessage(message, capabilities, &error);
+    DBusMessage *msg =
+            QDBusMessagePrivate::toDBusMessage(message, connectionCapabilities(), &error);
     if (!msg) {
         qWarning("QDBusConnection: error: could not send message to service \"%s\" path \"%s\" interface \"%s\" member \"%s\": %s",
                  qPrintable(message.service()), qPrintable(message.path()),
diff --git a/src/dbus/qdbusmessage.cpp b/src/dbus/qdbusmessage.cpp
index 1625dcdfea..01d55280d6 100644
--- a/src/dbus/qdbusmessage.cpp
+++ b/src/dbus/qdbusmessage.cpp
@@ -282,7 +282,7 @@ QDBusMessage QDBusMessagePrivate::makeLocal(const QDBusConnectionPrivate &conn,
             // we must marshall and demarshall again so as to create QDBusArgument
             // entries for the complex types
             QDBusError error;
-            DBusMessage *message = toDBusMessage(asSent, conn.capabilities, &error);
+            DBusMessage *message = toDBusMessage(asSent, conn.connectionCapabilities(), &error);
             if (!message) {
                 // failed to marshall, so it's a call error
                 return QDBusMessage::createError(error);
@@ -290,7 +290,7 @@ QDBusMessage QDBusMessagePrivate::makeLocal(const QDBusConnectionPrivate &conn,
 
             q_dbus_message_set_sender(message, conn.baseService.toUtf8());
 
-            QDBusMessage retval = fromDBusMessage(message, conn.capabilities);
+            QDBusMessage retval = fromDBusMessage(message, conn.connectionCapabilities());
             retval.d_ptr->localMessage = true;
             q_dbus_message_unref(message);
             if (retval.d_ptr->service.isEmpty())