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// Copyright (C) 2021 The Qt Company Ltd.
// Copyright (C) 2019 Luxoft Sweden AB
// Copyright (C) 2018 Pelagicore AG
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
#include <QDebug>
#include <QFileInfo>
#include <QDBusConnection>
#include <QDBusConnectionInterface>
#include <QDBusMessage>
#include <QDBusContext>
#include <QDBusAbstractAdaptor>
#include <QMetaMethod>
#include <algorithm>
#include "utilities.h"
#include "exception.h"
#include "dbuspolicy.h"
#include "dbuscontextadaptor.h"
using namespace Qt::StringLiterals;
QT_BEGIN_NAMESPACE_AM
DBusPolicy *DBusPolicy::s_instance = nullptr;
DBusPolicy::~DBusPolicy()
{
Q_ASSERT(s_instance == this);
s_instance = nullptr;
}
DBusPolicy *DBusPolicy::instance()
{
return s_instance;
}
// This uses function pointers to avoid strict coupling between AM modules:
// * applicationIdsForPid normally maps to ApplicationManager::identifyAllApplications
// * capabilitiesForApplicationId normally maps to ApplicationManager::capabilities
DBusPolicy *DBusPolicy::createInstance(const std::function<QStringList (qint64)> &applicationIdsForPid,
const std::function<QStringList (const QString &)> &capabilitiesForApplicationId)
{
Q_ASSERT(!s_instance);
s_instance = new DBusPolicy();
s_instance->m_applicationIdsForPid = applicationIdsForPid;
s_instance->m_capabilitiesForApplicationId = capabilitiesForApplicationId;
return s_instance;
}
bool DBusPolicy::add(const QDBusAbstractAdaptor *dbusAdaptor, const QVariantMap &yamlFragment)
{
QMap<QByteArray, DBusPolicyEntry> result;
const QMetaObject *mo = dbusAdaptor->metaObject();
for (auto it = yamlFragment.cbegin(); it != yamlFragment.cend(); ++it) {
const QByteArray func = it.key().toLocal8Bit();
bool found = false;
for (int mi = mo->methodOffset(); mi < mo->methodCount(); ++mi) {
if (mo->method(mi).name() == func) {
found = true;
break;
}
}
if (!found)
return false;
const QVariantMap &policy = it->toMap();
DBusPolicyEntry dbp;
const QVariantList uidList = policy.value(u"uids"_s).toList();
for (const QVariant &v : uidList) {
bool ok;
if (uint uid = v.toUInt(&ok); ok)
dbp.m_uids << uid;
}
std::sort(dbp.m_uids.begin(), dbp.m_uids.end());
dbp.m_executables = variantToStringList(policy.value(u"executables"_s));
dbp.m_executables.sort();
dbp.m_capabilities = variantToStringList(policy.value(u"capabilities"_s));
dbp.m_capabilities.sort();
result.insert(func, dbp);
}
m_policies.insert(dbusAdaptor, result);
return true;
}
void DBusPolicy::check(const QDBusAbstractAdaptor *dbusAdaptor, const QByteArray &function)
{
#if !defined(Q_OS_UNIX)
Q_UNUSED(dbusAdaptor)
Q_UNUSED(function)
#else
Q_ASSERT(dbusAdaptor);
QDBusContext *dbusContext = dbusAdaptor ? qobject_cast<DBusContextAdaptor *>(dbusAdaptor->parent())
: nullptr;
Q_ASSERT(dbusContext);
if (!dbusAdaptor || !dbusContext || !dbusContext->calledFromDBus())
throw Exception("cannot evalutate policy without a valid D-Bus context");
auto ia = m_policies.constFind(dbusAdaptor);
if (ia == m_policies.cend())
return; // no policy for interface
auto ip = (*ia).find(function);
if (ip == (*ia).cend())
return; // no policy for the function
uint cachedCallerPid = 0;
auto callerPid = [&] {
if (!cachedCallerPid)
cachedCallerPid = dbusContext->connection().interface()->servicePid(dbusContext->message().service());
return cachedCallerPid;
};
int checksDone = 0; // the default is 'deny', so we need to keep track of 'allow' rules
if (!ip->m_capabilities.isEmpty()) {
Q_ASSERT(m_capabilitiesForApplicationId);
Q_ASSERT(m_applicationIdsForPid);
if (!m_capabilitiesForApplicationId || !m_applicationIdsForPid)
throw Exception("cannot evaluate capabilities policy without application manager integration");
const QStringList apps = m_applicationIdsForPid(callerPid());
if (apps.size() > 1)
throw Exception("multiple apps per pid (%1) are not supported").arg(callerPid());
const QString appId = !apps.isEmpty() ? apps.constFirst() : QString();
const QStringList appCaps = m_capabilitiesForApplicationId(appId);
bool match = false;
for (const QString &cap : ip->m_capabilities)
match = match && std::binary_search(appCaps.cbegin(), appCaps.cend(), cap);
if (!match)
throw Exception("application '%1' has insufficient capabilities").arg(appId);
++checksDone;
}
if (!ip->m_executables.isEmpty()) {
# if defined(Q_OS_LINUX)
QString executable = QFileInfo(u"/proc/"_s + QString::number(callerPid()) + u"/exe"_s).symLinkTarget();
if (executable.isEmpty())
throw Exception("cannot get executable for pid '%1'").arg(callerPid());
if (std::binary_search(ip->m_executables.cbegin(), ip->m_executables.cend(), executable))
throw Exception("executable '%1' is denied").arg(executable);
++checksDone;
# else
throw Exception("the executables policy is not supported on this platform");
# endif // defined(Q_OS_LINUX)
}
if (!ip->m_uids.isEmpty()) {
uint uid = dbusContext->connection().interface()->serviceUid(dbusContext->message().service());
if (std::binary_search(ip->m_uids.cbegin(), ip->m_uids.cend(), uid))
throw Exception("uid '%1' is denied").arg(uid);
++checksDone;
}
if (!checksDone)
throw Exception("denied");
#endif // !defined(Q_OS_UNIX)
}
QT_END_NAMESPACE_AM
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