From 264e97625abe2e0334f97de17f6ffb52582888ab Mon Sep 17 00:00:00 2001
From: Albert Astals Cid <aacid@kde.org>
Date: Wed, 10 May 2017 10:06:07 +0200
Subject: Verify that whoever is calling us is actually who he says he is

CVE-2017-8422
---
 kdecore/auth/AuthBackend.cpp                       |  5 ++++
 kdecore/auth/AuthBackend.h                         |  7 ++++++
 kdecore/auth/backends/dbus/DBusHelperProxy.cpp     | 27 ++++++++++++++++++++--
 kdecore/auth/backends/dbus/DBusHelperProxy.h       |  6 ++++-
 .../auth/backends/policykit/PolicyKitBackend.cpp   |  5 ++++
 kdecore/auth/backends/policykit/PolicyKitBackend.h |  1 +
 kdecore/auth/backends/polkit-1/Polkit1Backend.cpp  |  5 ++++
 kdecore/auth/backends/polkit-1/Polkit1Backend.h    |  1 +
 8 files changed, 54 insertions(+), 3 deletions(-)

diff --git a/kdecore/auth/AuthBackend.cpp b/kdecore/auth/AuthBackend.cpp
index c953b81..0ba4650 100644
--- a/kdecore/auth/AuthBackend.cpp
+++ b/kdecore/auth/AuthBackend.cpp
@@ -54,6 +54,11 @@ void AuthBackend::setCapabilities(AuthBackend::Capabilities capabilities)
     d->capabilities = capabilities;
 }

+AuthBackend::ExtraCallerIDVerificationMethod AuthBackend::extraCallerIDVerificationMethod() const
+{
+    return NoExtraCallerIDVerificationMethod;
+}
+
 bool AuthBackend::actionExists(const QString& action)
 {
     Q_UNUSED(action);
diff --git a/kdecore/auth/AuthBackend.h b/kdecore/auth/AuthBackend.h
index a86732e..6f4b1bc 100644
--- a/kdecore/auth/AuthBackend.h
+++ b/kdecore/auth/AuthBackend.h
@@ -43,6 +43,12 @@ public:
     };
     Q_DECLARE_FLAGS(Capabilities, Capability)

+    enum ExtraCallerIDVerificationMethod {
+        NoExtraCallerIDVerificationMethod,
+        VerifyAgainstDBusServiceName,
+        VerifyAgainstDBusServicePid,
+    };
+
     AuthBackend();
     virtual ~AuthBackend();
     virtual void setupAction(const QString &action) = 0;
@@ -50,6 +56,7 @@ public:
     virtual Action::AuthStatus authorizeAction(const QString &action) = 0;
     virtual Action::AuthStatus actionStatus(const QString &action) = 0;
     virtual QByteArray callerID() const = 0;
+    virtual ExtraCallerIDVerificationMethod extraCallerIDVerificationMethod() const;
     virtual bool isCallerAuthorized(const QString &action, QByteArray callerID) = 0;
     virtual bool actionExists(const QString &action);

diff --git a/kdecore/auth/backends/dbus/DBusHelperProxy.cpp b/kdecore/auth/backends/dbus/DBusHelperProxy.cpp
index 9557a0f..ca59f1c 100644
--- a/kdecore/auth/backends/dbus/DBusHelperProxy.cpp
+++ b/kdecore/auth/backends/dbus/DBusHelperProxy.cpp
@@ -271,6 +271,29 @@ void DBusHelperProxy::performActions(QByteArray blob, const QByteArray &callerID
     }
 }

+bool DBusHelperProxy::isCallerAuthorized(const QString &action, const QByteArray &callerID)
+{
+    // Check the caller is really who it says it is
+    switch (BackendsManager::authBackend()->extraCallerIDVerificationMethod()) {
+        case AuthBackend::NoExtraCallerIDVerificationMethod:
+        break;
+
+        case AuthBackend::VerifyAgainstDBusServiceName:
+            if (message().service().toUtf8() != callerID) {
+                return false;
+            }
+        break;
+
+        case AuthBackend::VerifyAgainstDBusServicePid:
+            if (connection().interface()->servicePid(message().service()).value() != callerID.toUInt()) {
+                return false;
+            }
+        break;
+    }
+
+    return BackendsManager::authBackend()->isCallerAuthorized(action, callerID);
+}
+
 QByteArray DBusHelperProxy::performAction(const QString &action, const QByteArray &callerID, QByteArray arguments)
 {
     if (!responder) {
@@ -295,7 +318,7 @@ QByteArray DBusHelperProxy::performAction(const QString &action, const QByteArra
     QTimer *timer = responder->property("__KAuth_Helper_Shutdown_Timer").value<QTimer*>();
     timer->stop();

-    if (BackendsManager::authBackend()->isCallerAuthorized(action, callerID)) {
+    if (isCallerAuthorized(action, callerID)) {
         QString slotname = action;
         if (slotname.startsWith(m_name + QLatin1Char('.'))) {
             slotname = slotname.right(slotname.length() - m_name.length() - 1);
@@ -338,7 +361,7 @@ uint DBusHelperProxy::authorizeAction(const QString& action, const QByteArray& c
     QTimer *timer = responder->property("__KAuth_Helper_Shutdown_Timer").value<QTimer*>();
     timer->stop();

-    if (BackendsManager::authBackend()->isCallerAuthorized(action, callerID)) {
+    if (isCallerAuthorized(action, callerID)) {
         retVal = static_cast<uint>(Action::Authorized);
     } else {
         retVal = static_cast<uint>(Action::Denied);
diff --git a/kdecore/auth/backends/dbus/DBusHelperProxy.h b/kdecore/auth/backends/dbus/DBusHelperProxy.h
index 455cf51..264f6cc 100644
--- a/kdecore/auth/backends/dbus/DBusHelperProxy.h
+++ b/kdecore/auth/backends/dbus/DBusHelperProxy.h
@@ -21,6 +21,7 @@
 #ifndef DBUS_HELPER_PROXY_H
 #define DBUS_HELPER_PROXY_H

+#include <QDBusContext>
 #include <QVariant>
 #include "HelperProxy.h"
 #include "kauthactionreply.h"
@@ -28,7 +29,7 @@
 namespace KAuth
 {

-class DBusHelperProxy : public HelperProxy
+class DBusHelperProxy : public HelperProxy, protected QDBusContext
 {
     Q_OBJECT
     Q_INTERFACES(KAuth::HelperProxy)
@@ -73,6 +74,9 @@ signals:

 private slots:
     void remoteSignalReceived(int type, const QString &action, QByteArray blob);
+
+private:
+    bool isCallerAuthorized(const QString &action, const QByteArray &callerID);
 };

 } // namespace Auth
diff --git a/kdecore/auth/backends/policykit/PolicyKitBackend.cpp b/kdecore/auth/backends/policykit/PolicyKitBackend.cpp
index 3be97f2..9d041d1 100644
--- a/kdecore/auth/backends/policykit/PolicyKitBackend.cpp
+++ b/kdecore/auth/backends/policykit/PolicyKitBackend.cpp
@@ -78,6 +78,11 @@ QByteArray PolicyKitBackend::callerID() const
     return a;
 }

+AuthBackend::ExtraCallerIDVerificationMethod Polkit1Backend::extraCallerIDVerificationMethod() const
+{
+    return VerifyAgainstDBusServicePid;
+}
+
 bool PolicyKitBackend::isCallerAuthorized(const QString &action, QByteArray callerID)
 {
     QDataStream s(&callerID, QIODevice::ReadOnly);
diff --git a/kdecore/auth/backends/policykit/PolicyKitBackend.h b/kdecore/auth/backends/policykit/PolicyKitBackend.h
index 7154e93..0d3d8f9 100644
--- a/kdecore/auth/backends/policykit/PolicyKitBackend.h
+++ b/kdecore/auth/backends/policykit/PolicyKitBackend.h
@@ -40,6 +40,7 @@ public:
     virtual Action::AuthStatus authorizeAction(const QString&);
     virtual Action::AuthStatus actionStatus(const QString&);
     virtual QByteArray callerID() const;
+    virtual ExtraCallerIDVerificationMethod extraCallerIDVerificationMethod() const;
     virtual bool isCallerAuthorized(const QString &action, QByteArray callerID);

 private Q_SLOTS:
diff --git a/kdecore/auth/backends/polkit-1/Polkit1Backend.cpp b/kdecore/auth/backends/polkit-1/Polkit1Backend.cpp
index 732d2cb..63c0e1e 100644
--- a/kdecore/auth/backends/polkit-1/Polkit1Backend.cpp
+++ b/kdecore/auth/backends/polkit-1/Polkit1Backend.cpp
@@ -163,6 +163,11 @@ QByteArray Polkit1Backend::callerID() const
     return QDBusConnection::systemBus().baseService().toUtf8();
 }

+AuthBackend::ExtraCallerIDVerificationMethod Polkit1Backend::extraCallerIDVerificationMethod() const
+{
+    return VerifyAgainstDBusServiceName;
+}
+
 bool Polkit1Backend::isCallerAuthorized(const QString &action, QByteArray callerID)
 {
     PolkitQt1::SystemBusNameSubject subject(QString::fromUtf8(callerID));
diff --git a/kdecore/auth/backends/polkit-1/Polkit1Backend.h b/kdecore/auth/backends/polkit-1/Polkit1Backend.h
index 18ed1a2..d579da2 100644
--- a/kdecore/auth/backends/polkit-1/Polkit1Backend.h
+++ b/kdecore/auth/backends/polkit-1/Polkit1Backend.h
@@ -48,6 +48,7 @@ public:
     virtual Action::AuthStatus authorizeAction(const QString&);
     virtual Action::AuthStatus actionStatus(const QString&);
     virtual QByteArray callerID() const;
+    virtual ExtraCallerIDVerificationMethod extraCallerIDVerificationMethod() const;
     virtual bool isCallerAuthorized(const QString &action, QByteArray callerID);
     virtual bool actionExists(const QString& action);

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