494 lines
14 KiB
PHP
494 lines
14 KiB
PHP
<?php
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/**
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* @author Lukas Reschke <lukas@owncloud.com>
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*
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* @copyright Copyright (c) 2016, ownCloud, Inc.
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* @license AGPL-3.0
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*
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* This code is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License, version 3,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License, version 3,
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* along with this program. If not, see <http://www.gnu.org/licenses/>
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*
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*/
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namespace OC\IntegrityCheck;
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use OC\IntegrityCheck\Exceptions\InvalidSignatureException;
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use OC\IntegrityCheck\Helpers\AppLocator;
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use OC\IntegrityCheck\Helpers\EnvironmentHelper;
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use OC\IntegrityCheck\Helpers\FileAccessHelper;
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use OC\Integritycheck\Iterator\ExcludeFileByNameFilterIterator;
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use OC\IntegrityCheck\Iterator\ExcludeFoldersByPathFilterIterator;
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use OCP\App\IAppManager;
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use OCP\ICache;
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use OCP\ICacheFactory;
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use OCP\IConfig;
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use phpseclib\Crypt\RSA;
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use phpseclib\File\X509;
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/**
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* Class Checker handles the code signing using X.509 and RSA. ownCloud ships with
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* a public root certificate certificate that allows to issue new certificates that
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* will be trusted for signing code. The CN will be used to verify that a certificate
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* given to a third-party developer may not be used for other applications. For
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* example the author of the application "calendar" would only receive a certificate
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* only valid for this application.
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*
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* @package OC\IntegrityCheck
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*/
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class Checker {
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const CACHE_KEY = 'oc.integritycheck.checker';
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/** @var EnvironmentHelper */
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private $environmentHelper;
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/** @var AppLocator */
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private $appLocator;
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/** @var FileAccessHelper */
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private $fileAccessHelper;
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/** @var IConfig */
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private $config;
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/** @var ICache */
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private $cache;
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/** @var IAppManager */
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private $appManager;
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/**
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* @param EnvironmentHelper $environmentHelper
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* @param FileAccessHelper $fileAccessHelper
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* @param AppLocator $appLocator
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* @param IConfig $config
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* @param ICacheFactory $cacheFactory
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* @param IAppManager $appManager
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*/
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public function __construct(EnvironmentHelper $environmentHelper,
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FileAccessHelper $fileAccessHelper,
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AppLocator $appLocator,
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IConfig $config = null,
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ICacheFactory $cacheFactory,
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IAppManager $appManager = null) {
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$this->environmentHelper = $environmentHelper;
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$this->fileAccessHelper = $fileAccessHelper;
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$this->appLocator = $appLocator;
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$this->config = $config;
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$this->cache = $cacheFactory->create(self::CACHE_KEY);
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$this->appManager = $appManager;
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}
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/**
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* Whether code signing is enforced or not.
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*
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* @return bool
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*/
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public function isCodeCheckEnforced() {
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// FIXME: Once the signing server is instructed to sign daily, beta and
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// RCs as well these need to be included also.
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$signedChannels = [
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'stable',
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];
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if(!in_array($this->environmentHelper->getChannel(), $signedChannels, true)) {
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return false;
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}
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/**
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* This config option is undocumented and supposed to be so, it's only
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* applicable for very specific scenarios and we should not advertise it
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* too prominent. So please do not add it to config.sample.php.
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*/
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$isIntegrityCheckDisabled = $this->config->getSystemValue('integrity.check.disabled', false);
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if($isIntegrityCheckDisabled === true) {
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return false;
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}
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return true;
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}
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/**
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* Enumerates all files belonging to the folder. Sensible defaults are excluded.
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*
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* @param string $folderToIterate
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* @return \RecursiveIteratorIterator
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*/
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private function getFolderIterator($folderToIterate) {
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$dirItr = new \RecursiveDirectoryIterator(
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$folderToIterate,
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\RecursiveDirectoryIterator::SKIP_DOTS
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);
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$excludeGenericFilesIterator = new ExcludeFileByNameFilterIterator($dirItr);
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$excludeFoldersIterator = new ExcludeFoldersByPathFilterIterator($excludeGenericFilesIterator);
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return new \RecursiveIteratorIterator(
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$excludeFoldersIterator,
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\RecursiveIteratorIterator::SELF_FIRST
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);
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}
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/**
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* Returns an array of ['filename' => 'SHA512-hash-of-file'] for all files found
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* in the iterator.
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*
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* @param \RecursiveIteratorIterator $iterator
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* @param string $path
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* @return array Array of hashes.
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*/
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private function generateHashes(\RecursiveIteratorIterator $iterator,
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$path) {
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$hashes = [];
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$baseDirectoryLength = strlen($path);
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foreach($iterator as $filename => $data) {
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/** @var \DirectoryIterator $data */
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if($data->isDir()) {
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continue;
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}
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$relativeFileName = substr($filename, $baseDirectoryLength);
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// Exclude signature.json files in the appinfo and root folder
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if($relativeFileName === '/appinfo/signature.json') {
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continue;
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}
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// Exclude signature.json files in the appinfo and core folder
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if($relativeFileName === '/core/signature.json') {
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continue;
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}
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$hashes[$relativeFileName] = hash_file('sha512', $filename);
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}
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return $hashes;
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}
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/**
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* Creates the signature data
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*
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* @param array $hashes
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* @param X509 $certificate
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* @param RSA $privateKey
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* @return string
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*/
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private function createSignatureData(array $hashes,
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X509 $certificate,
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RSA $privateKey) {
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ksort($hashes);
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$privateKey->setSignatureMode(RSA::SIGNATURE_PSS);
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$privateKey->setMGFHash('sha512');
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$signature = $privateKey->sign(json_encode($hashes));
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return [
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'hashes' => $hashes,
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'signature' => base64_encode($signature),
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'certificate' => $certificate->saveX509($certificate->currentCert),
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];
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}
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/**
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* Write the signature of the specified app
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*
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* @param string $appId
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* @param X509 $certificate
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* @param RSA $privateKey
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* @throws \Exception
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*/
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public function writeAppSignature($appId,
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X509 $certificate,
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RSA $privateKey) {
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$path = $this->appLocator->getAppPath($appId);
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$iterator = $this->getFolderIterator($path);
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$hashes = $this->generateHashes($iterator, $path);
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$signature = $this->createSignatureData($hashes, $certificate, $privateKey);
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$this->fileAccessHelper->file_put_contents(
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$path . '/appinfo/signature.json',
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json_encode($signature, JSON_PRETTY_PRINT)
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);
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}
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/**
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* Write the signature of core
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*
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* @param X509 $certificate
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* @param RSA $rsa
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*/
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public function writeCoreSignature(X509 $certificate,
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RSA $rsa) {
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$iterator = $this->getFolderIterator($this->environmentHelper->getServerRoot());
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$hashes = $this->generateHashes($iterator, $this->environmentHelper->getServerRoot());
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$signatureData = $this->createSignatureData($hashes, $certificate, $rsa);
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$this->fileAccessHelper->file_put_contents(
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$this->environmentHelper->getServerRoot() . '/core/signature.json',
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json_encode($signatureData, JSON_PRETTY_PRINT)
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);
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}
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/**
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* Verifies the signature for the specified path.
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*
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* @param string $signaturePath
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* @param string $basePath
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* @param string $certificateCN
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* @return array
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* @throws InvalidSignatureException
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* @throws \Exception
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*/
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private function verify($signaturePath, $basePath, $certificateCN) {
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if(!$this->isCodeCheckEnforced()) {
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return [];
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}
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$signatureData = json_decode($this->fileAccessHelper->file_get_contents($signaturePath), true);
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if(!is_array($signatureData)) {
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throw new InvalidSignatureException('Signature data not found.');
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}
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$expectedHashes = $signatureData['hashes'];
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ksort($expectedHashes);
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$signature = base64_decode($signatureData['signature']);
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$certificate = $signatureData['certificate'];
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// Check if certificate is signed by ownCloud Root Authority
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$x509 = new \phpseclib\File\X509();
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$rootCertificatePublicKey = $this->fileAccessHelper->file_get_contents($this->environmentHelper->getServerRoot().'/resources/codesigning/root.crt');
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$x509->loadCA($rootCertificatePublicKey);
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$x509->loadX509($certificate);
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if(!$x509->validateSignature()) {
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throw new InvalidSignatureException('Certificate is not valid.');
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}
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// Verify if certificate has proper CN. "core" CN is always trusted.
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if($x509->getDN(X509::DN_OPENSSL)['CN'] !== $certificateCN && $x509->getDN(X509::DN_OPENSSL)['CN'] !== 'core') {
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throw new InvalidSignatureException(
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sprintf('Certificate is not valid for required scope. (Requested: %s, current: %s)', $certificateCN, $x509->getDN(true))
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);
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}
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// Check if the signature of the files is valid
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$rsa = new \phpseclib\Crypt\RSA();
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$rsa->loadKey($x509->currentCert['tbsCertificate']['subjectPublicKeyInfo']['subjectPublicKey']);
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$rsa->setSignatureMode(RSA::SIGNATURE_PSS);
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$rsa->setMGFHash('sha512');
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if(!$rsa->verify(json_encode($expectedHashes), $signature)) {
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throw new InvalidSignatureException('Signature could not get verified.');
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}
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// Compare the list of files which are not identical
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$currentInstanceHashes = $this->generateHashes($this->getFolderIterator($basePath), $basePath);
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$differencesA = array_diff($expectedHashes, $currentInstanceHashes);
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$differencesB = array_diff($currentInstanceHashes, $expectedHashes);
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$differences = array_unique(array_merge($differencesA, $differencesB));
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$differenceArray = [];
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foreach($differences as $filename => $hash) {
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// Check if file should not exist in the new signature table
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if(!array_key_exists($filename, $expectedHashes)) {
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$differenceArray['EXTRA_FILE'][$filename]['expected'] = '';
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$differenceArray['EXTRA_FILE'][$filename]['current'] = $hash;
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continue;
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}
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// Check if file is missing
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if(!array_key_exists($filename, $currentInstanceHashes)) {
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$differenceArray['FILE_MISSING'][$filename]['expected'] = $expectedHashes[$filename];
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$differenceArray['FILE_MISSING'][$filename]['current'] = '';
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continue;
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}
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// Check if hash does mismatch
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if($expectedHashes[$filename] !== $currentInstanceHashes[$filename]) {
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$differenceArray['INVALID_HASH'][$filename]['expected'] = $expectedHashes[$filename];
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$differenceArray['INVALID_HASH'][$filename]['current'] = $currentInstanceHashes[$filename];
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continue;
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}
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// Should never happen.
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throw new \Exception('Invalid behaviour in file hash comparison experienced. Please report this error to the developers.');
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}
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return $differenceArray;
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}
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/**
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* Whether the code integrity check has passed successful or not
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*
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* @return bool
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*/
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public function hasPassedCheck() {
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$results = $this->getResults();
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if(empty($results)) {
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return true;
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}
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return false;
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}
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/**
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* @return array
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*/
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public function getResults() {
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$cachedResults = $this->cache->get(self::CACHE_KEY);
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if(!is_null($cachedResults)) {
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return json_decode($cachedResults, true);
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}
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return json_decode($this->config->getAppValue('core', self::CACHE_KEY, '{}'), true);
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}
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/**
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* Stores the results in the app config as well as cache
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*
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* @param string $scope
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* @param array $result
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*/
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private function storeResults($scope, array $result) {
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$resultArray = $this->getResults();
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unset($resultArray[$scope]);
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if(!empty($result)) {
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$resultArray[$scope] = $result;
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}
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$this->config->setAppValue('core', self::CACHE_KEY, json_encode($resultArray));
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$this->cache->set(self::CACHE_KEY, json_encode($resultArray));
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}
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/**
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*
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* Clean previous results for a proper rescanning. Otherwise
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*/
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private function cleanResults() {
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$this->config->deleteAppValue('core', self::CACHE_KEY);
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$this->cache->remove(self::CACHE_KEY);
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}
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/**
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* Verify the signature of $appId. Returns an array with the following content:
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* [
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* 'FILE_MISSING' =>
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* [
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* 'filename' => [
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* 'expected' => 'expectedSHA512',
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* 'current' => 'currentSHA512',
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* ],
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* ],
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* 'EXTRA_FILE' =>
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* [
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* 'filename' => [
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* 'expected' => 'expectedSHA512',
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* 'current' => 'currentSHA512',
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* ],
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* ],
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* 'INVALID_HASH' =>
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* [
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* 'filename' => [
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* 'expected' => 'expectedSHA512',
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* 'current' => 'currentSHA512',
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* ],
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* ],
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* ]
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*
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* Array may be empty in case no problems have been found.
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*
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* @param string $appId
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* @param string $path Optional path. If none is given it will be guessed.
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* @return array
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*/
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public function verifyAppSignature($appId, $path = '') {
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try {
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if($path === '') {
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$path = $this->appLocator->getAppPath($appId);
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}
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$result = $this->verify(
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$path . '/appinfo/signature.json',
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$path,
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$appId
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);
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} catch (\Exception $e) {
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$result = [
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'EXCEPTION' => [
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'class' => get_class($e),
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'message' => $e->getMessage(),
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],
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];
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}
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$this->storeResults($appId, $result);
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return $result;
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}
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/**
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* Verify the signature of core. Returns an array with the following content:
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* [
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* 'FILE_MISSING' =>
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* [
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* 'filename' => [
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* 'expected' => 'expectedSHA512',
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* 'current' => 'currentSHA512',
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* ],
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* ],
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* 'EXTRA_FILE' =>
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* [
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* 'filename' => [
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* 'expected' => 'expectedSHA512',
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* 'current' => 'currentSHA512',
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* ],
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* ],
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* 'INVALID_HASH' =>
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* [
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* 'filename' => [
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* 'expected' => 'expectedSHA512',
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* 'current' => 'currentSHA512',
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* ],
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* ],
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* ]
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*
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* Array may be empty in case no problems have been found.
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*
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* @return array
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*/
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public function verifyCoreSignature() {
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try {
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$result = $this->verify(
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$this->environmentHelper->getServerRoot() . '/core/signature.json',
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$this->environmentHelper->getServerRoot(),
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'core'
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);
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} catch (\Exception $e) {
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$result = [
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'EXCEPTION' => [
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'class' => get_class($e),
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'message' => $e->getMessage(),
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],
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];
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}
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$this->storeResults('core', $result);
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return $result;
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}
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/**
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* Verify the core code of the instance as well as all applicable applications
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* and store the results.
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*/
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public function runInstanceVerification() {
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$this->cleanResults();
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$this->verifyCoreSignature();
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$appIds = $this->appLocator->getAllApps();
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foreach($appIds as $appId) {
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// If an application is shipped a valid signature is required
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$isShipped = $this->appManager->isShipped($appId);
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$appNeedsToBeChecked = false;
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if ($isShipped) {
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$appNeedsToBeChecked = true;
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} elseif ($this->fileAccessHelper->file_exists($this->appLocator->getAppPath($appId) . '/appinfo/signature.json')) {
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// Otherwise only if the application explicitly ships a signature.json file
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$appNeedsToBeChecked = true;
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}
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if($appNeedsToBeChecked) {
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$this->verifyAppSignature($appId);
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}
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}
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}
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}
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