cache = $cacheFactory->createDistributed(self::CACHE_KEY); } /** * Whether code signing is enforced or not. * * @return bool */ public function isCodeCheckEnforced(): bool { $notSignedChannels = [ '', 'git']; if (\in_array($this->serverVersion->getChannel(), $notSignedChannels, true)) { return false; } /** * This config option is undocumented and supposed to be so, it's only * applicable for very specific scenarios and we should not advertise it * too prominent. So please do not add it to config.sample.php. */ return !($this->config?->getSystemValueBool('integrity.check.disabled', false) ?? false); } /** * Enumerates all files belonging to the folder. Sensible defaults are excluded. * * @param string $folderToIterate * @param string $root * @return \RecursiveIteratorIterator * @throws \Exception */ private function getFolderIterator(string $folderToIterate, string $root = ''): \RecursiveIteratorIterator { $dirItr = new \RecursiveDirectoryIterator( $folderToIterate, \RecursiveDirectoryIterator::SKIP_DOTS ); if ($root === '') { $root = \OC::$SERVERROOT; } $root = rtrim($root, '/'); $excludeGenericFilesIterator = new ExcludeFileByNameFilterIterator($dirItr); $excludeFoldersIterator = new ExcludeFoldersByPathFilterIterator($excludeGenericFilesIterator, $root); return new \RecursiveIteratorIterator( $excludeFoldersIterator, \RecursiveIteratorIterator::SELF_FIRST ); } /** * Returns an array of ['filename' => 'SHA512-hash-of-file'] for all files found * in the iterator. * * @param \RecursiveIteratorIterator $iterator * @param string $path * @return array Array of hashes. */ private function generateHashes(\RecursiveIteratorIterator $iterator, string $path): array { $hashes = []; $baseDirectoryLength = \strlen($path); foreach ($iterator as $filename => $data) { /** @var \DirectoryIterator $data */ if ($data->isDir()) { continue; } $relativeFileName = substr($filename, $baseDirectoryLength); $relativeFileName = ltrim($relativeFileName, '/'); // Exclude signature.json files in the appinfo and root folder if ($relativeFileName === 'appinfo/signature.json') { continue; } // Exclude signature.json files in the appinfo and core folder if ($relativeFileName === 'core/signature.json') { continue; } // The .htaccess file in the root folder of ownCloud can contain // custom content after the installation due to the fact that dynamic // content is written into it at installation time as well. This // includes for example the 404 and 403 instructions. // Thus we ignore everything below the first occurrence of // "#### DO NOT CHANGE ANYTHING ABOVE THIS LINE ####" and have the // hash generated based on this. if ($filename === $this->environmentHelper->getServerRoot() . '/.htaccess') { $fileContent = file_get_contents($filename); $explodedArray = explode('#### DO NOT CHANGE ANYTHING ABOVE THIS LINE ####', $fileContent); if (\count($explodedArray) === 2) { $hashes[$relativeFileName] = hash('sha512', $explodedArray[0]); continue; } } if ($filename === $this->environmentHelper->getServerRoot() . '/core/js/mimetypelist.js') { $oldMimetypeList = new GenerateMimetypeFileBuilder(); $newFile = $oldMimetypeList->generateFile($this->mimeTypeDetector->getAllAliases()); $oldFile = $this->fileAccessHelper->file_get_contents($filename); if ($newFile === $oldFile) { $hashes[$relativeFileName] = hash('sha512', $oldMimetypeList->generateFile($this->mimeTypeDetector->getOnlyDefaultAliases())); continue; } } $hashes[$relativeFileName] = hash_file('sha512', $filename); } return $hashes; } /** * Creates the signature data * * @param array $hashes * @param X509 $certificate * @param RSA $privateKey * @return array */ private function createSignatureData(array $hashes, X509 $certificate, RSA $privateKey): array { ksort($hashes); $privateKey->setSignatureMode(RSA::SIGNATURE_PSS); $privateKey->setMGFHash('sha512'); // See https://tools.ietf.org/html/rfc3447#page-38 $privateKey->setSaltLength(0); $signature = $privateKey->sign(json_encode($hashes)); return [ 'hashes' => $hashes, 'signature' => base64_encode($signature), 'certificate' => $certificate->saveX509($certificate->currentCert), ]; } /** * Write the signature of the app in the specified folder * * @param string $path * @param X509 $certificate * @param RSA $privateKey * @throws \Exception */ public function writeAppSignature($path, X509 $certificate, RSA $privateKey) { $appInfoDir = $path . '/appinfo'; try { $this->fileAccessHelper->assertDirectoryExists($appInfoDir); $iterator = $this->getFolderIterator($path); $hashes = $this->generateHashes($iterator, $path); $signature = $this->createSignatureData($hashes, $certificate, $privateKey); $this->fileAccessHelper->file_put_contents( $appInfoDir . '/signature.json', json_encode($signature, JSON_PRETTY_PRINT) ); } catch (\Exception $e) { if (!$this->fileAccessHelper->is_writable($appInfoDir)) { throw new \Exception($appInfoDir . ' is not writable'); } throw $e; } } /** * Write the signature of core * * @param X509 $certificate * @param RSA $rsa * @param string $path * @throws \Exception */ public function writeCoreSignature(X509 $certificate, RSA $rsa, $path) { $coreDir = $path . '/core'; try { $this->fileAccessHelper->assertDirectoryExists($coreDir); $iterator = $this->getFolderIterator($path, $path); $hashes = $this->generateHashes($iterator, $path); $signatureData = $this->createSignatureData($hashes, $certificate, $rsa); $this->fileAccessHelper->file_put_contents( $coreDir . '/signature.json', json_encode($signatureData, JSON_PRETTY_PRINT) ); } catch (\Exception $e) { if (!$this->fileAccessHelper->is_writable($coreDir)) { throw new \Exception($coreDir . ' is not writable'); } throw $e; } } /** * Split the certificate file in individual certs * * @param string $cert * @return string[] */ private function splitCerts(string $cert): array { preg_match_all('([\-]{3,}[\S\ ]+?[\-]{3,}[\S\s]+?[\-]{3,}[\S\ ]+?[\-]{3,})', $cert, $matches); return $matches[0]; } /** * Verifies the signature for the specified path. * * @param string $signaturePath * @param string $basePath * @param string $certificateCN * @param bool $forceVerify * @return array * @throws InvalidSignatureException * @throws \Exception */ private function verify(string $signaturePath, string $basePath, string $certificateCN, bool $forceVerify = false): array { if (!$forceVerify && !$this->isCodeCheckEnforced()) { return []; } $content = $this->fileAccessHelper->file_get_contents($signaturePath); $signatureData = null; if (\is_string($content)) { $signatureData = json_decode($content, true); } if (!\is_array($signatureData)) { throw new InvalidSignatureException('Signature data not found.'); } $expectedHashes = $signatureData['hashes']; ksort($expectedHashes); $signature = base64_decode($signatureData['signature']); $certificate = $signatureData['certificate']; // Check if certificate is signed by Nextcloud Root Authority $x509 = new \phpseclib\File\X509(); $rootCertificatePublicKey = $this->fileAccessHelper->file_get_contents($this->environmentHelper->getServerRoot() . '/resources/codesigning/root.crt'); $rootCerts = $this->splitCerts($rootCertificatePublicKey); foreach ($rootCerts as $rootCert) { $x509->loadCA($rootCert); } $x509->loadX509($certificate); if (!$x509->validateSignature()) { throw new InvalidSignatureException('Certificate is not valid.'); } // Verify if certificate has proper CN. "core" CN is always trusted. if ($x509->getDN(X509::DN_OPENSSL)['CN'] !== $certificateCN && $x509->getDN(X509::DN_OPENSSL)['CN'] !== 'core') { throw new InvalidSignatureException( sprintf('Certificate is not valid for required scope. (Requested: %s, current: CN=%s)', $certificateCN, $x509->getDN(true)['CN']) ); } // Check if the signature of the files is valid $rsa = new \phpseclib\Crypt\RSA(); $rsa->loadKey($x509->currentCert['tbsCertificate']['subjectPublicKeyInfo']['subjectPublicKey']); $rsa->setSignatureMode(RSA::SIGNATURE_PSS); $rsa->setMGFHash('sha512'); // See https://tools.ietf.org/html/rfc3447#page-38 $rsa->setSaltLength(0); if (!$rsa->verify(json_encode($expectedHashes), $signature)) { throw new InvalidSignatureException('Signature could not get verified.'); } // Fixes for the updater as shipped with ownCloud 9.0.x: The updater is // replaced after the code integrity check is performed. // // Due to this reason we exclude the whole updater/ folder from the code // integrity check. if ($basePath === $this->environmentHelper->getServerRoot()) { foreach ($expectedHashes as $fileName => $hash) { if (str_starts_with($fileName, 'updater/')) { unset($expectedHashes[$fileName]); } } } // Compare the list of files which are not identical $currentInstanceHashes = $this->generateHashes($this->getFolderIterator($basePath), $basePath); $differencesA = array_diff($expectedHashes, $currentInstanceHashes); $differencesB = array_diff($currentInstanceHashes, $expectedHashes); $differences = array_unique(array_merge($differencesA, $differencesB)); $differenceArray = []; foreach ($differences as $filename => $hash) { // Check if file should not exist in the new signature table if (!array_key_exists($filename, $expectedHashes)) { $differenceArray['EXTRA_FILE'][$filename]['expected'] = ''; $differenceArray['EXTRA_FILE'][$filename]['current'] = $hash; continue; } // Check if file is missing if (!array_key_exists($filename, $currentInstanceHashes)) { $differenceArray['FILE_MISSING'][$filename]['expected'] = $expectedHashes[$filename]; $differenceArray['FILE_MISSING'][$filename]['current'] = ''; continue; } // Check if hash does mismatch if ($expectedHashes[$filename] !== $currentInstanceHashes[$filename]) { $differenceArray['INVALID_HASH'][$filename]['expected'] = $expectedHashes[$filename]; $differenceArray['INVALID_HASH'][$filename]['current'] = $currentInstanceHashes[$filename]; continue; } // Should never happen. throw new \Exception('Invalid behaviour in file hash comparison experienced. Please report this error to the developers.'); } return $differenceArray; } /** * Whether the code integrity check has passed successful or not * * @return bool */ public function hasPassedCheck(): bool { $results = $this->getResults(); if ($results !== null && empty($results)) { return true; } return false; } /** * @return array|null Either the results or null if no results available */ public function getResults(): ?array { $cachedResults = $this->cache->get(self::CACHE_KEY); if (!\is_null($cachedResults) and $cachedResults !== false) { return json_decode($cachedResults, true); } if ($this->appConfig?->hasKey('core', self::CACHE_KEY, lazy: true)) { return $this->appConfig->getValueArray('core', self::CACHE_KEY, lazy: true); } // No results available return null; } /** * Stores the results in the app config as well as cache * * @param string $scope * @param array $result */ private function storeResults(string $scope, array $result) { $resultArray = $this->getResults() ?? []; unset($resultArray[$scope]); if (!empty($result)) { $resultArray[$scope] = $result; } $this->appConfig?->setValueArray('core', self::CACHE_KEY, $resultArray, lazy: true); $this->cache->set(self::CACHE_KEY, json_encode($resultArray)); } /** * * Clean previous results for a proper rescanning. Otherwise */ private function cleanResults() { $this->appConfig->deleteKey('core', self::CACHE_KEY); $this->cache->remove(self::CACHE_KEY); } /** * Verify the signature of $appId. Returns an array with the following content: * [ * 'FILE_MISSING' => * [ * 'filename' => [ * 'expected' => 'expectedSHA512', * 'current' => 'currentSHA512', * ], * ], * 'EXTRA_FILE' => * [ * 'filename' => [ * 'expected' => 'expectedSHA512', * 'current' => 'currentSHA512', * ], * ], * 'INVALID_HASH' => * [ * 'filename' => [ * 'expected' => 'expectedSHA512', * 'current' => 'currentSHA512', * ], * ], * ] * * Array may be empty in case no problems have been found. * * @param string $appId * @param string $path Optional path. If none is given it will be guessed. * @param bool $forceVerify * @return array */ public function verifyAppSignature(string $appId, string $path = '', bool $forceVerify = false): array { try { if ($path === '') { $path = $this->appLocator->getAppPath($appId); } $result = $this->verify( $path . '/appinfo/signature.json', $path, $appId, $forceVerify ); } catch (\Exception $e) { $result = [ 'EXCEPTION' => [ 'class' => \get_class($e), 'message' => $e->getMessage(), ], ]; } $this->storeResults($appId, $result); return $result; } /** * Verify the signature of core. Returns an array with the following content: * [ * 'FILE_MISSING' => * [ * 'filename' => [ * 'expected' => 'expectedSHA512', * 'current' => 'currentSHA512', * ], * ], * 'EXTRA_FILE' => * [ * 'filename' => [ * 'expected' => 'expectedSHA512', * 'current' => 'currentSHA512', * ], * ], * 'INVALID_HASH' => * [ * 'filename' => [ * 'expected' => 'expectedSHA512', * 'current' => 'currentSHA512', * ], * ], * ] * * Array may be empty in case no problems have been found. * * @return array */ public function verifyCoreSignature(): array { try { $result = $this->verify( $this->environmentHelper->getServerRoot() . '/core/signature.json', $this->environmentHelper->getServerRoot(), 'core' ); } catch (\Exception $e) { $result = [ 'EXCEPTION' => [ 'class' => \get_class($e), 'message' => $e->getMessage(), ], ]; } $this->storeResults('core', $result); return $result; } /** * Verify the core code of the instance as well as all applicable applications * and store the results. */ public function runInstanceVerification() { $this->cleanResults(); $this->verifyCoreSignature(); $appIds = $this->appManager->getAllAppsInAppsFolders(); foreach ($appIds as $appId) { // If an application is shipped a valid signature is required $isShipped = $this->appManager->isShipped($appId); $appNeedsToBeChecked = false; if ($isShipped) { $appNeedsToBeChecked = true; } elseif ($this->fileAccessHelper->file_exists($this->appLocator->getAppPath($appId) . '/appinfo/signature.json')) { // Otherwise only if the application explicitly ships a signature.json file $appNeedsToBeChecked = true; } if ($appNeedsToBeChecked) { $this->verifyAppSignature($appId); } } } }