1 files changed, 314 insertions, 0 deletions
diff --git a/src/input/pvsCheckPrivileges.cpp b/src/input/pvsCheckPrivileges.cpp
new file mode 100644
index 0000000..56073bc
--- /dev/null
+++ b/src/input/pvsCheckPrivileges.cpp
@@ -0,0 +1,314 @@
+/*
+ # Copyright (c) 2009 - OpenSLX Project, Computer Center University of Freiburg
+ #
+ # This program is free software distributed under the GPL version 2.
+ # See http://openslx.org/COPYING
+ #
+ # If you have any feedback please consult http://openslx.org/feedback and
+ # send your suggestions, praise, or complaints to feedback@openslx.org
+ #
+ # General information about OpenSLX can be found at http://openslx.org/
+ # --------------------------------------------------------------------------
+ # pvsCheckPrivileges.cpp:
+ #  - A small program that checks whether or not it is called from
+ #    a physical seat and conditionally executes the pvs input daemon.
+ #    Additional security-relevant conditions should be checked here.
+ #
+ #    The program is called with exactly one parameter, specifying the
+ #    number of the file descriptor which is to be passed to its child.
+ # --------------------------------------------------------------------------
+ */
+
+#include <unistd.h>
+#include <iostream>
+#include <cerrno>
+#include <cstdlib>
+#include <QCoreApplication>
+#include <QDir>
+#include <QFileInfo>
+#include <QTimer>
+#include <QtDBus/QDBusArgument>
+#include <QtDBus/QDBusConnection>
+#include <QtDBus/QDBusInterface>
+#include <QtDBus/QDBusMetaType>
+#include <QtDBus/QDBusReply>
+#include <QtGlobal>
+#include <QDebug>
+#include <QUuid>
+#include "pvsCheckPrivileges.h"
+
+using namespace std;
+
+#define TIMEOUT_VALUE 10000 /* Wait for max. 10 seconds */
+
+// We need these classes for PolicyKit access:
+struct PolKitSubject {
+	QString subject_kind;
+	QMap<QString, QVariant> subject_details;
+};
+Q_DECLARE_METATYPE(PolKitSubject);
+
+QDBusArgument& operator<<(QDBusArgument& arg, PolKitSubject const& subj)
+{
+	arg.beginStructure();
+	arg << subj.subject_kind << subj.subject_details;
+	arg.endStructure();
+	return arg;
+}
+
+QDBusArgument const& operator>>(QDBusArgument const& arg, PolKitSubject& subj)
+{
+	arg.beginStructure();
+	arg >> subj.subject_kind >> subj.subject_details;
+	arg.endStructure();
+	return arg;
+}
+
+struct PolKitAuthReply {
+	bool isAuthorized;
+	bool isChallenge;
+	QMap<QString, QString> details;
+};
+Q_DECLARE_METATYPE(PolKitAuthReply);
+
+QDBusArgument& operator<<(QDBusArgument& arg, PolKitAuthReply const& reply)
+{
+	arg.beginStructure();
+	arg << reply.isAuthorized << reply.isChallenge << reply.details;
+	arg.endStructure();
+	return arg;
+}
+
+QDBusArgument const& operator>>(QDBusArgument const& arg, PolKitAuthReply& reply)
+{
+	arg.beginStructure();
+	arg >> reply.isAuthorized >> reply.isChallenge >> reply.details;
+	arg.endStructure();
+	return arg;
+}
+
+// We need to pass QMap<QString, QString> to QVariant:
+typedef QMap<QString, QString> QStringStringMap;
+Q_DECLARE_METATYPE(QStringStringMap)
+
+PVSCheckPrivileges* PVSCheckPrivileges::instance()
+{
+	static PVSCheckPrivileges static_instance;
+	return &static_instance;
+}
+
+PVSCheckPrivileges::PVSCheckPrivileges()
+{
+}
+
+PVSCheckPrivileges::~PVSCheckPrivileges()
+{
+}
+
+QString PVSCheckPrivileges::getSessionReference(CachedInputContext const& sender)
+{
+	if(!sender.isValid())
+	{
+		return QString();
+	}
+
+	QString sessionReference = _savedConsoleKitSession.value(sender, QString());
+	if(sessionReference.isNull())
+	{
+		QDBusConnection conn = QDBusConnection::systemBus();
+		// Find the name of the current session:
+		QDBusInterface manager("org.freedesktop.ConsoleKit", "/org/freedesktop/ConsoleKit/Manager", "org.freedesktop.ConsoleKit.Manager", conn);
+		QDBusReply<QDBusObjectPath> replyGetSession = manager.call(QDBus::Block, "GetSessionForUnixProcess", (quint32)sender.pid);
+		if(!replyGetSession.isValid())
+		{
+			qWarning("Reply to GetSessionForUnixProcess is invalid: %s: %s", replyGetSession.error().name().toLocal8Bit().constData(), replyGetSession.error().message().toLocal8Bit().constData());
+			return QString();
+		}
+		_savedConsoleKitSession[sender] = sessionReference = replyGetSession.value().path();
+	}
+	return sessionReference;
+}
+
+PVSCheckPrivileges::SessionKind PVSCheckPrivileges::getSessionKind(CachedInputContext const& sender)
+{
+	if(!sender.isValid())
+	{
+		return SESSION_UNKNOWN;
+	}
+
+	// if the sender is root, we always suppose he works locally.
+	if(sender.uid == 0)
+	{
+		return SESSION_LOCAL;
+	}
+
+	QString sessionReference = getSessionReference(sender);
+	if(sessionReference.isNull())
+	{
+		return SESSION_LOOKUP_FAILURE;
+	}
+
+	QDBusConnection conn = QDBusConnection::systemBus();
+	QDBusInterface session("org.freedesktop.ConsoleKit", sessionReference, "org.freedesktop.ConsoleKit.Session", conn);
+	QDBusReply<bool> replyIsLocal = session.call(QDBus::Block, "IsLocal");
+
+	if(!replyIsLocal.isValid())
+	{
+		qWarning("Unable to find out whether the current session is local: %s: %s", replyIsLocal.error().name().toLocal8Bit().constData(), replyIsLocal.error().message().toLocal8Bit().constData());
+		return SESSION_LOOKUP_FAILURE;
+	}
+	return replyIsLocal.value() ? SESSION_LOCAL : SESSION_NONLOCAL;
+}
+
+PVSCheckPrivileges::UserPrivilege PVSCheckPrivileges::getUserPrivilege(CachedInputContext const& sender)
+{
+	// Always allow root:
+	if(sender.uid == 0)
+		return USER_PRIVILEGED;
+
+	// For PolKit, we need the start-time of the process.
+	// On Linux, we can get it from /proc:
+	QString procStat = QString("/proc/%1/stat").arg(sender.pid);
+	QFile procStatFile(procStat);
+	if(!procStatFile.exists())
+	{
+		qWarning("Could not look up any info on process %d, its %s file does not exist", sender.pid, procStat.toLocal8Bit().constData());
+		return USER_LOOKUP_FAILURE;
+	}
+	procStatFile.open(QIODevice::ReadOnly);
+	QByteArray procStatBytes = procStatFile.readAll();
+	qDebug() << "Read stat file: " << procStatBytes;
+	QString procStatLine = QString::fromLocal8Bit(procStatBytes.constData(), procStatBytes.length());
+	QStringList procStatFields = procStatLine.split(QRegExp("\\s+"));
+	qDebug() << "Found stat fields: " << procStatFields;
+	bool ok;
+	quint64 startTime = procStatFields[21].toULongLong(&ok);
+	if(!ok)
+	{
+		qWarning("Could not find out start time for process %d", (int)sender.pid);
+		return USER_LOOKUP_FAILURE;
+	}
+
+	// Okay, we got the startTime. Now ask PolicyKit:
+
+	QDBusConnection conn = QDBusConnection::systemBus();
+	QDBusInterface intf("org.freedesktop.PolicyKit1", "/org/freedesktop/PolicyKit1/Authority", "org.freedesktop.PolicyKit1.Authority", conn);
+	PolKitSubject subj;
+	subj.subject_kind = "unix-process";
+	subj.subject_details["pid"] = (quint32)sender.pid;
+	subj.subject_details["start-time"] = startTime;
+	QDBusReply<PolKitAuthReply> reply = intf.call(QDBus::Block,
+			QLatin1String("CheckAuthorization"),
+			QVariant::fromValue(subj),
+			"org.openslx.pvs.privilegedinput",
+			QVariant::fromValue(QMap<QString, QString>()) /* No details */,
+			(quint32)1 /* Allow Interaction */,
+			QUuid::createUuid().toString() /* Cancellation ID */);
+	if(!reply.isValid())
+	{
+		QDBusError err = reply.error();
+
+		qWarning("Reply to CheckAuthorization is invalid: %s: %s", err.name().toLocal8Bit().constData(), err.message().toLocal8Bit().constData());
+		return USER_LOOKUP_FAILURE;
+	}
+	return reply.value().isAuthorized ? USER_PRIVILEGED : USER_UNPRIVILEGED;
+}
+
+QString PVSCheckPrivileges::getX11SessionName(CachedInputContext const& sender)
+{
+    QString sessionReference = getSessionReference(sender);
+    if(sessionReference.isNull())
+    {
+    	return QString();
+    }
+
+	QDBusConnection conn = QDBusConnection::systemBus();
+    QDBusInterface intf("org.freedesktop.ConsoleKit", sessionReference, "org.freedesktop.ConsoleKit.Session", conn);
+	QDBusReply<QString> reply = intf.call(QDBus::Block, QLatin1String("GetX11Display"));
+	if(!reply.isValid())
+	{
+		QDBusError err = reply.error();
+
+		qWarning("Reply to GetX11Display is invalid: %s: %s", err.name().toLocal8Bit().constData(), err.message().toLocal8Bit().constData());
+		return QString();
+	}
+
+	return reply.value();
+}
+
+QString PVSCheckPrivileges::getX11DisplayDevice(CachedInputContext const& sender)
+{
+	QString sessionReference = getSessionReference(sender);
+	if(sessionReference.isNull())
+	{
+		return QString();
+	}
+
+	QDBusConnection conn = QDBusConnection::systemBus();
+	QDBusInterface intf("org.freedesktop.ConsoleKit", sessionReference, "org.freedesktop.ConsoleKit.Session", conn);
+	QDBusReply<QString> reply = intf.call(QDBus::Block, QLatin1String("GetX11DisplayDevice"));
+	if(!reply.isValid())
+	{
+		QDBusError err = reply.error();
+
+		qWarning("Reply to GetX11DisplayDevice is invalid: %s: %s", err.name().toLocal8Bit().constData(), err.message().toLocal8Bit().constData());
+		return QString();
+	}
+
+	return reply.value();
+}
+
+bool PVSCheckPrivileges::require(SessionKind sessionKind, CachedInputContext const& sender)
+{
+	SessionKind cachedSessionKind;
+
+	if(sessionKind < SESSION_NONLOCAL)
+	{
+		if((cachedSessionKind = _savedSessionKind.value(sender, SESSION_UNKNOWN)) == SESSION_UNKNOWN)
+		{
+			cachedSessionKind = getSessionKind(sender);
+			if(cachedSessionKind != SESSION_LOOKUP_FAILURE)
+				_savedSessionKind[sender] = cachedSessionKind;
+			qDebug("Got session kind: %s", toString(cachedSessionKind).toLocal8Bit().constData());
+		}
+		if(cachedSessionKind > sessionKind)
+			return false;
+	}
+
+	return true;
+}
+
+bool PVSCheckPrivileges::require(UserPrivilege userPrivilege, CachedInputContext const& sender)
+{
+	UserPrivilege cachedUserPrivilege;
+
+	if(userPrivilege < USER_UNPRIVILEGED)
+	{
+		if((cachedUserPrivilege = _savedUserPrivilege.value(sender, USER_UNKNOWN)) == USER_UNKNOWN)
+		{
+			cachedUserPrivilege = getUserPrivilege(sender);
+			if(cachedUserPrivilege != USER_LOOKUP_FAILURE)
+				_savedUserPrivilege[sender] = cachedUserPrivilege;
+			qDebug("Got user privilege: %s", toString(cachedUserPrivilege).toLocal8Bit().constData());
+		}
+		if(cachedUserPrivilege > userPrivilege)
+			return false;
+	}
+	return true;
+}
+
+bool PVSCheckPrivileges::require(SessionKind sessionKind,
+		UserPrivilege userPrivilege,
+		CachedInputContext const& sender)
+{
+	if(!require(sessionKind, sender))
+		return false;
+	if(!require(userPrivilege, sender))
+		return false;
+	return true;
+}
+
+uint qHash(CachedInputContext const& p)
+{
+	return qHash(qMakePair(p.pid, qMakePair(p.uid, p.gid)));
+}