Merge branch 'master' of openslx.org:pvs

Conflicts:
	CMakeLists.txt
	src/core/pvsConnectionManager.cpp
	src/pvs.cpp
	src/pvs.h

1 files changed, 550 insertions, 0 deletions

diff --git a/src/input/pvsCheckPrivileges.cpp b/src/input/pvsCheckPrivileges.cpp
new file mode 100644
index 0000000..2026c0a
--- /dev/null
+++ b/src/input/pvsCheckPrivileges.cpp
@@ -0,0 +1,550 @@
+/*
+ # 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 <sys/types.h>
+#include <pwd.h>
+#include <grp.h>
+#include <unistd.h>
+#include <iostream>
+#include <cerrno>
+#include <cstdlib>
+#include <cstring>
+#include <QCoreApplication>
+#include <QDir>
+#include <QFileInfo>
+#include <QFileSystemWatcher>
+#include <QSettings>
+#include <QTimer>
+#include <QtDBus/QDBusArgument>
+#include <QtDBus/QDBusConnection>
+#include <QtDBus/QDBusInterface>
+#include <QtDBus/QDBusMetaType>
+#include <QtDBus/QDBusReply>
+#include <QtGlobal>
+#include <QDebug>
+#include <QUuid>
+#include "pvsPrivInputSocket.h"
+#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 = 0;
+	if(!static_instance)
+	{
+		static_instance = new PVSCheckPrivileges();
+	}
+	return static_instance;
+}
+
+void PVSCheckPrivileges::deleteInstance()
+{
+	delete instance();
+}
+
+PVSCheckPrivileges::PVSCheckPrivileges(QObject* parent)
+	: QObject(parent)
+{
+	// initialise our cache:
+	updateCachedUserDatabase();
+	rereadConfiguration();
+
+	// and make it update itself:
+	QStringList paths;
+	paths << "/etc/passwd" << "/etc/group" << pvsPrivInputGetSettingsPath();
+	_watcher = new QFileSystemWatcher(paths, this);
+	connect(_watcher, SIGNAL(fileChanged(QString const&)), this, SLOT(updateCachedUserDatabase()));
+	connect(_watcher, SIGNAL(fileChanged(QString const&)), this, SLOT(rereadConfiguration()));
+}
+
+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;
+	}
+
+	// Or if the user is one of those enumerated in the privileged-users configuration value:
+	if(_privilegedUsers.contains(sender.uid))
+	{
+		return USER_PRIVILEGED;
+	}
+
+	// Or if the user is a member of one of the groups enumerated in the privileged-groups configuration value:
+	foreach(gid_t gid, _privilegedGroups)
+	{
+		if(_userGroupMap.contains(sender.uid, gid))
+		{
+			return USER_PRIVILEGED;
+		}
+	}
+
+	// User is not trivially privileged, so try to check with PolicyKit.
+#ifdef HAVE_POLKIT // but only if it is present
+	// 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;
+#else
+	return USER_UNPRIVILEGED;
+#endif
+}
+
+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)
+	{
+		// All sessions are at least non-local
+		return true;
+	}
+	else if(sessionKind == SESSION_LOCAL)
+	{
+		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());
+		}
+
+		switch(cachedSessionKind)
+		{
+		case SESSION_LOOKUP_FAILURE:
+		case SESSION_UNKNOWN:
+		{
+			// If we cannot find out the correct session kind, look up what we should do in
+			// the configuration:
+			QSettings* config = pvsPrivInputGetSettings();
+			QVariant assumeLocal = config->value("assume-session-local", false);
+			if(!assumeLocal.canConvert(QVariant::Bool))
+			{
+				qWarning("There is an assume-session-local setting, but cannot convert it to boolean");
+				return false;
+			}
+			return assumeLocal.toBool();
+		}
+		case SESSION_LOCAL:
+			return true;
+		case SESSION_NONLOCAL:
+			return false;
+		default:
+			qWarning("Internal error: Undefined session kind %d", (int)cachedSessionKind);
+			return false;
+		}
+	}
+	else
+	{
+		qWarning("Internal error: It does not make sense to require an unknown session or undefined session kind %d", (int)sessionKind);
+		return false;
+	}
+}
+
+bool PVSCheckPrivileges::require(UserPrivilege userPrivilege, CachedInputContext const& sender)
+{
+	UserPrivilege cachedUserPrivilege;
+
+	if(userPrivilege == USER_UNPRIVILEGED)
+	{
+		// All users are unprivileged
+		return true;
+	}
+	else if(userPrivilege == USER_PRIVILEGED)
+	{
+		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());
+		}
+
+		switch(cachedUserPrivilege)
+		{
+		case USER_LOOKUP_FAILURE:
+		case USER_UNKNOWN:
+		{
+			// If we cannot find out the correct user privilege level, look up what we should do in
+			// the configuration:
+			QSettings* config = pvsPrivInputGetSettings();
+			QVariant assumePrivileged = config->value("assume-user-privileged", false);
+			if(!assumePrivileged.canConvert(QVariant::Bool))
+			{
+				qWarning("There is an assume-session-local setting, but cannot convert it to boolean");
+				return false;
+			}
+			return assumePrivileged.toBool();
+		}
+		case USER_PRIVILEGED:
+			return true;
+		case USER_UNPRIVILEGED:
+			return false;
+		default:
+			qWarning("Internal error: Found undefined user privilege level %d", (int)cachedUserPrivilege);
+			_savedUserPrivilege.remove(sender);
+			return false;
+		}
+	}
+	else
+	{
+		qWarning("Internal error: It does not make sense to require an unknown or undefined user privilege level %d", (int)userPrivilege);
+		return false;
+	}
+}
+
+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)));
+}
+
+void PVSCheckPrivileges::updateCachedUserDatabase()
+{
+	QHash<QString, uid_t> userNames;
+
+	_userGroupMap.clear();
+
+	// assemble a list of known users and their primary groups:
+	setpwent();	// open the user database
+	struct passwd* userrec;
+	while((userrec = getpwent()))
+	{
+		userNames.insert(userrec->pw_name, userrec->pw_uid);
+		_userGroupMap.insert(userrec->pw_uid, userrec->pw_gid);
+	}
+	endpwent(); // close the database
+
+	// augment with secondary groups:
+	setgrent(); // open the group database
+	struct group* grouprec;
+	while((grouprec = getgrent()))
+	{
+		char** membername = grouprec->gr_mem;
+		while(*membername)
+		{
+			uid_t uid = userNames.value(*membername, (uid_t)-1);
+			if(uid != (uid_t)-1)
+			{
+				_userGroupMap.insert(uid, grouprec->gr_gid);
+			}
+			membername++;
+		}
+	}
+	endgrent();
+
+	// decisions may have changed, so clear the caches:
+	_savedUserPrivilege.clear();
+}
+
+void PVSCheckPrivileges::rereadConfiguration()
+{
+	QSettings* settings = pvsPrivInputReopenSettings();
+
+	_privilegedGroups.clear();
+	QVariant groupList = settings->value("privileged-groups");
+	if(groupList.isValid())
+	{
+		if(!groupList.canConvert(QVariant::StringList))
+		{
+			qWarning("There is a privileged-groups setting, but it cannot be converted to a list of strings.");
+			goto endGroupListScan;
+		}
+
+		QStringList groups = groupList.toStringList();
+		foreach(QString groupName, groups)
+		{
+			bool ok;
+			gid_t gid = groupName.toUInt(&ok);
+			if(ok)
+			{
+				_privilegedGroups.append(gid);
+			}
+			else
+			{
+				// lookup the name:
+				QByteArray groupNameBytes = groupName.toLocal8Bit();
+				struct group* group = getgrnam(groupNameBytes.constData());
+				if(group)
+				{
+					_privilegedGroups.append(group->gr_gid);
+				}
+				else
+				{
+					qWarning("privileged-groups setting contains %s which is neither a numeric GID "
+							"nor a valid group name. Skipping.",
+							groupNameBytes.constData());
+				}
+			}
+		}
+	}
+
+endGroupListScan:
+	_privilegedUsers.clear();
+	QVariant userList = settings->value("privileged-users");
+	if(userList.isValid())
+	{
+		if(!userList.canConvert(QVariant::StringList))
+		{
+			qWarning("There is a privileged-users setting, but it cannot be converted to a list of strings.");
+			goto endUserListScan;
+		}
+
+		QStringList users = userList.toStringList();
+		foreach(QString userName, users)
+		{
+			bool ok;
+			uid_t uid = userName.toUInt(&ok);
+			if(ok)
+			{
+				_privilegedUsers.append(uid);
+			}
+			else
+			{
+				// lookup the name:
+				QByteArray userNameBytes = userName.toLocal8Bit();
+				struct passwd* user = getpwnam(userNameBytes.constData());
+				if(user)
+				{
+					_privilegedUsers.append(user->pw_uid);
+				}
+				else
+				{
+					qWarning("privileged-users setting contains %s which is neither a numeric UID "
+							"nor a valid user name. Skipping.",
+							userNameBytes.constData());
+				}
+			}
+		}
+	}
+
+endUserListScan:
+	return;
+}