668 lines
19 KiB
PHP
668 lines
19 KiB
PHP
<?php
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/**
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* ownCloud
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*
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* @copyright (C) 2014 ownCloud, Inc.
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*
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* @author Bjoern Schiessle <schiessle@owncloud.com>
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* @author Robin Appelman <icewind@owncloud.com>
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* @author Sam Tuke <samtuke@owncloud.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
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* License as published by the Free Software Foundation; either
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* version 3 of the License, or any later version.
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*
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* This library 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
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* License along with this library. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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/**
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* transparently encrypted filestream
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*
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* you can use it as wrapper around an existing stream by setting CryptStream::$sourceStreams['foo']=array('path'=>$path,'stream'=>$stream)
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* and then fopen('crypt://streams/foo');
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*/
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namespace OCA\Files_Encryption;
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use OCA\Files_Encryption\Exception\EncryptionException;
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/**
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* Provides 'crypt://' stream wrapper protocol.
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* @note We use a stream wrapper because it is the most secure way to handle
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* decrypted content transfers. There is no safe way to decrypt the entire file
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* somewhere on the server, so we have to encrypt and decrypt blocks on the fly.
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* @note Paths used with this protocol MUST BE RELATIVE. Use URLs like:
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* crypt://filename, or crypt://subdirectory/filename, NOT
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* crypt:///home/user/owncloud/data. Otherwise keyfiles will be put in
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* [owncloud]/data/user/files_encryption/keyfiles/home/user/owncloud/data and
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* will not be accessible to other methods.
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* @note Data read and written must always be 8192 bytes long, as this is the
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* buffer size used internally by PHP. The encryption process makes the input
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* data longer, and input is chunked into smaller pieces in order to result in
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* a 8192 encrypted block size.
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* @note When files are deleted via webdav, or when they are updated and the
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* previous version deleted, this is handled by OC\Files\View, and thus the
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* encryption proxies are used and keyfiles deleted.
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*/
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class Stream {
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const PADDING_CHAR = '-';
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private $plainKey;
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private $encKeyfiles;
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private $rawPath; // The raw path relative to the data dir
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private $relPath; // rel path to users file dir
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private $userId;
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private $keyId;
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private $handle; // Resource returned by fopen
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private $meta = array(); // Header / meta for source stream
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private $writeCache;
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private $size;
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private $unencryptedSize;
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private $publicKey;
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private $encKeyfile;
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private $newFile; // helper var, we only need to write the keyfile for new files
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private $isLocalTmpFile = false; // do we operate on a local tmp file
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private $localTmpFile; // path of local tmp file
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private $headerWritten = false;
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private $containHeader = false; // the file contain a header
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private $cipher; // cipher used for encryption/decryption
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/** @var \OCA\Files_Encryption\Util */
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private $util;
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/**
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* @var \OC\Files\View
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*/
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private $rootView; // a fsview object set to '/'
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/**
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* @var \OCA\Files_Encryption\Session
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*/
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private $session;
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private $privateKey;
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/**
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* @param string $path raw path relative to data/
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* @param string $mode
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* @param int $options
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* @param string $opened_path
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* @return bool
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* @throw \OCA\Files_Encryption\Exception\EncryptionException
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*/
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public function stream_open($path, $mode, $options, &$opened_path) {
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// read default cipher from config
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$this->cipher = Helper::getCipher();
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// assume that the file already exist before we decide it finally in getKey()
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$this->newFile = false;
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$this->rootView = new \OC\Files\View('/');
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$this->session = new Session($this->rootView);
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$this->privateKey = $this->session->getPrivateKey();
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if ($this->privateKey === false) {
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throw new EncryptionException('Session does not contain a private key, maybe your login password changed?',
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EncryptionException::PRIVATE_KEY_MISSING);
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}
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$normalizedPath = \OC\Files\Filesystem::normalizePath(str_replace('crypt://', '', $path));
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$originalFile = Helper::getPathFromTmpFile($normalizedPath);
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if ($originalFile) {
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$this->rawPath = $originalFile;
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$this->isLocalTmpFile = true;
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$this->localTmpFile = $normalizedPath;
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} else {
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$this->rawPath = $normalizedPath;
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}
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$this->util = new Util($this->rootView, Helper::getUser($this->rawPath));
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// get the key ID which we want to use, can be the users key or the
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// public share key
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$this->keyId = $this->util->getKeyId();
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$fileType = Helper::detectFileType($this->rawPath);
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switch ($fileType) {
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case Util::FILE_TYPE_FILE:
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$this->relPath = Helper::stripUserFilesPath($this->rawPath);
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$user = \OC::$server->getUserSession()->getUser();
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$this->userId = $user ? $user->getUID() : Helper::getUserFromPath($this->rawPath);
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break;
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case Util::FILE_TYPE_VERSION:
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$this->relPath = Helper::getPathFromVersion($this->rawPath);
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$this->userId = Helper::getUserFromPath($this->rawPath);
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break;
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case Util::FILE_TYPE_CACHE:
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$this->relPath = Helper::getPathFromCachedFile($this->rawPath);
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Helper::mkdirr($this->rawPath, new \OC\Files\View('/'));
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$user = \OC::$server->getUserSession()->getUser();
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$this->userId = $user ? $user->getUID() : Helper::getUserFromPath($this->rawPath);
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break;
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default:
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\OCP\Util::writeLog('Encryption library', 'failed to open file "' . $this->rawPath . '" expecting a path to "files", "files_versions" or "cache"', \OCP\Util::ERROR);
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return false;
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}
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// Disable fileproxies so we can get the file size and open the source file without recursive encryption
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$proxyStatus = \OC_FileProxy::$enabled;
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\OC_FileProxy::$enabled = false;
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if (
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$mode === 'w'
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or $mode === 'w+'
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or $mode === 'wb'
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or $mode === 'wb+'
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) {
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// We're writing a new file so start write counter with 0 bytes
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$this->size = 0;
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$this->unencryptedSize = 0;
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} else {
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$this->size = $this->rootView->filesize($this->rawPath);
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$this->readHeader();
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}
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if ($this->isLocalTmpFile) {
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$this->handle = fopen($this->localTmpFile, $mode);
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} else {
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$this->handle = $this->rootView->fopen($this->rawPath, $mode);
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}
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\OC_FileProxy::$enabled = $proxyStatus;
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if (!is_resource($this->handle)) {
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\OCP\Util::writeLog('Encryption library', 'failed to open file "' . $this->rawPath . '"', \OCP\Util::ERROR);
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} else {
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$this->meta = stream_get_meta_data($this->handle);
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// sometimes fopen changes the mode, e.g. for a url "r" convert to "r+"
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// but we need to remember the original access type
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$this->meta['mode'] = $mode;
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}
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return is_resource($this->handle);
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}
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private function readHeader() {
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if ($this->isLocalTmpFile) {
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$handle = fopen($this->localTmpFile, 'r');
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} else {
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$handle = $this->rootView->fopen($this->rawPath, 'r');
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}
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if (is_resource($handle)) {
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$data = fread($handle, Crypt::BLOCKSIZE);
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$header = Crypt::parseHeader($data);
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$this->cipher = Crypt::getCipher($header);
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// remeber that we found a header
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if (!empty($header)) {
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$this->containHeader = true;
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}
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fclose($handle);
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}
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}
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/**
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* Returns the current position of the file pointer
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* @return int position of the file pointer
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*/
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public function stream_tell() {
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return ftell($this->handle);
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}
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/**
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* @param int $offset
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* @param int $whence
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* @return bool true if fseek was successful, otherwise false
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*/
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public function stream_seek($offset, $whence = SEEK_SET) {
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$this->flush();
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// ignore the header and just overstep it
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if ($this->containHeader) {
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$offset += Crypt::BLOCKSIZE;
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}
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// this wrapper needs to return "true" for success.
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// the fseek call itself returns 0 on succeess
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return !fseek($this->handle, $offset, $whence);
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}
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/**
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* @param int $count
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* @return bool|string
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* @throws \OCA\Files_Encryption\Exception\EncryptionException
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*/
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public function stream_read($count) {
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$this->writeCache = '';
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if ($count !== Crypt::BLOCKSIZE) {
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\OCP\Util::writeLog('Encryption library', 'PHP "bug" 21641 no longer holds, decryption system requires refactoring', \OCP\Util::FATAL);
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throw new EncryptionException('expected a blog size of 8192 byte', EncryptionException::UNEXPECTED_BLOG_SIZE);
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}
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// Get the data from the file handle
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$data = fread($this->handle, $count);
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// if this block contained the header we move on to the next block
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if (Crypt::isHeader($data)) {
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$data = fread($this->handle, $count);
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}
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$result = null;
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if (strlen($data)) {
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if (!$this->getKey()) {
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// Error! We don't have a key to decrypt the file with
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throw new \Exception(
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'Encryption key not found for "' . $this->rawPath . '" during attempted read via stream');
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} else {
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// Decrypt data
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$result = Crypt::symmetricDecryptFileContent($data, $this->plainKey, $this->cipher);
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}
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}
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return $result;
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}
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/**
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* Encrypt and pad data ready for writing to disk
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* @param string $plainData data to be encrypted
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* @param string $key key to use for encryption
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* @return string encrypted data on success, false on failure
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*/
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public function preWriteEncrypt($plainData, $key) {
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// Encrypt data to 'catfile', which includes IV
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if ($encrypted = Crypt::symmetricEncryptFileContent($plainData, $key, $this->cipher)) {
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return $encrypted;
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} else {
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return false;
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}
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}
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/**
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* Fetch the plain encryption key for the file and set it as plainKey property
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* @internal param bool $generate if true, a new key will be generated if none can be found
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* @return bool true on key found and set, false on key not found and new key generated and set
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*/
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public function getKey() {
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// Check if key is already set
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if (isset($this->plainKey) && isset($this->encKeyfile)) {
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return true;
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}
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$util = new Util($this->rootView, $this->userId);
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// Fetch and decrypt keyfile
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// Fetch existing keyfile
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$this->encKeyfile = Keymanager::getFileKey($this->rootView, $util, $this->relPath);
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// If a keyfile already exists
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if ($this->encKeyfile) {
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$shareKey = Keymanager::getShareKey($this->rootView, $this->keyId, $util, $this->relPath);
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// if there is no valid private key return false
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if ($this->privateKey === false) {
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// if private key is not valid redirect user to a error page
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Helper::redirectToErrorPage($this->session);
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return false;
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}
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if ($shareKey === false) {
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// if no share key is available redirect user to a error page
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Helper::redirectToErrorPage($this->session, Crypt::ENCRYPTION_NO_SHARE_KEY_FOUND);
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return false;
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}
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$this->plainKey = Crypt::multiKeyDecrypt($this->encKeyfile, $shareKey, $this->privateKey);
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return true;
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} else {
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$this->newFile = true;
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return false;
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}
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}
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/**
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* write header at beginning of encrypted file
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*
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* @throws \OCA\Files_Encryption\Exception\EncryptionException
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*/
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private function writeHeader() {
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$header = Crypt::generateHeader();
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if (strlen($header) > Crypt::BLOCKSIZE) {
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throw new EncryptionException('max header size exceeded', EncryptionException::ENCRYPTION_HEADER_TO_LARGE);
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}
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$paddedHeader = str_pad($header, Crypt::BLOCKSIZE, self::PADDING_CHAR, STR_PAD_RIGHT);
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fwrite($this->handle, $paddedHeader);
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$this->headerWritten = true;
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}
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/**
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* Handle plain data from the stream, and write it in 8192 byte blocks
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* @param string $data data to be written to disk
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* @note the data will be written to the path stored in the stream handle, set in stream_open()
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* @note $data is only ever be a maximum of 8192 bytes long. This is set by PHP internally. stream_write() is called multiple times in a loop on data larger than 8192 bytes
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* @note Because the encryption process used increases the length of $data, a writeCache is used to carry over data which would not fit in the required block size
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* @note Padding is added to each encrypted block to ensure that the resulting block is exactly 8192 bytes. This is removed during stream_read
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* @note PHP automatically updates the file pointer after writing data to reflect it's length. There is generally no need to update the poitner manually using fseek
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*/
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public function stream_write($data) {
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// if there is no valid private key return false
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if ($this->privateKey === false) {
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$this->size = 0;
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return strlen($data);
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}
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if ($this->headerWritten === false) {
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$this->writeHeader();
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}
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// Disable the file proxies so that encryption is not
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// automatically attempted when the file is written to disk -
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// we are handling that separately here and we don't want to
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// get into an infinite loop
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$proxyStatus = \OC_FileProxy::$enabled;
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\OC_FileProxy::$enabled = false;
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// Get the length of the unencrypted data that we are handling
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$length = strlen($data);
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// Find out where we are up to in the writing of data to the
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// file
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$pointer = ftell($this->handle);
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// Get / generate the keyfile for the file we're handling
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// If we're writing a new file (not overwriting an existing
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// one), save the newly generated keyfile
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if (!$this->getKey()) {
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$this->plainKey = Crypt::generateKey();
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}
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// If extra data is left over from the last round, make sure it
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// is integrated into the next 6126 / 8192 block
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if ($this->writeCache) {
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// Concat writeCache to start of $data
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$data = $this->writeCache . $data;
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// Clear the write cache, ready for reuse - it has been
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// flushed and its old contents processed
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$this->writeCache = '';
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}
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// While there still remains some data to be processed & written
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while (strlen($data) > 0) {
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// Remaining length for this iteration, not of the
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// entire file (may be greater than 8192 bytes)
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$remainingLength = strlen($data);
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// If data remaining to be written is less than the
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// size of 1 6126 byte block
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if ($remainingLength < 6126) {
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// Set writeCache to contents of $data
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// The writeCache will be carried over to the
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// next write round, and added to the start of
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// $data to ensure that written blocks are
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// always the correct length. If there is still
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// data in writeCache after the writing round
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// has finished, then the data will be written
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// to disk by $this->flush().
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$this->writeCache = $data;
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// Clear $data ready for next round
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$data = '';
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} else {
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// Read the chunk from the start of $data
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$chunk = substr($data, 0, 6126);
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$encrypted = $this->preWriteEncrypt($chunk, $this->plainKey);
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// Write the data chunk to disk. This will be
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// attended to the last data chunk if the file
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// being handled totals more than 6126 bytes
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fwrite($this->handle, $encrypted);
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// Remove the chunk we just processed from
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// $data, leaving only unprocessed data in $data
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// var, for handling on the next round
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$data = substr($data, 6126);
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}
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}
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$this->size = max($this->size, $pointer + $length);
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$this->unencryptedSize += $length;
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\OC_FileProxy::$enabled = $proxyStatus;
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return $length;
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}
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/**
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* @param int $option
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* @param int $arg1
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* @param int|null $arg2
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*/
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public function stream_set_option($option, $arg1, $arg2) {
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$return = false;
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switch ($option) {
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case STREAM_OPTION_BLOCKING:
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$return = stream_set_blocking($this->handle, $arg1);
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break;
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case STREAM_OPTION_READ_TIMEOUT:
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$return = stream_set_timeout($this->handle, $arg1, $arg2);
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break;
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case STREAM_OPTION_WRITE_BUFFER:
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$return = stream_set_write_buffer($this->handle, $arg1);
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}
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return $return;
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}
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/**
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* @return array
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*/
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public function stream_stat() {
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return fstat($this->handle);
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}
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/**
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* @param int $mode
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*/
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public function stream_lock($mode) {
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return flock($this->handle, $mode);
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}
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/**
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* @return bool
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*/
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public function stream_flush() {
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return fflush($this->handle);
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// Not a typo: http://php.net/manual/en/function.fflush.php
|
|
|
|
}
|
|
|
|
/**
|
|
* @return bool
|
|
*/
|
|
public function stream_eof() {
|
|
return feof($this->handle);
|
|
}
|
|
|
|
private function flush() {
|
|
|
|
if ($this->writeCache) {
|
|
|
|
// Set keyfile property for file in question
|
|
$this->getKey();
|
|
|
|
$encrypted = $this->preWriteEncrypt($this->writeCache, $this->plainKey);
|
|
|
|
fwrite($this->handle, $encrypted);
|
|
|
|
$this->writeCache = '';
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @return bool
|
|
*/
|
|
public function stream_close() {
|
|
|
|
$this->flush();
|
|
|
|
// if there is no valid private key return false
|
|
if ($this->privateKey === false) {
|
|
|
|
// cleanup
|
|
if ($this->meta['mode'] !== 'r' && $this->meta['mode'] !== 'rb' && !$this->isLocalTmpFile) {
|
|
|
|
// Disable encryption proxy to prevent recursive calls
|
|
$proxyStatus = \OC_FileProxy::$enabled;
|
|
\OC_FileProxy::$enabled = false;
|
|
|
|
if ($this->rootView->file_exists($this->rawPath) && $this->size === 0) {
|
|
fclose($this->handle);
|
|
$this->rootView->unlink($this->rawPath);
|
|
}
|
|
|
|
// Re-enable proxy - our work is done
|
|
\OC_FileProxy::$enabled = $proxyStatus;
|
|
}
|
|
|
|
// if private key is not valid redirect user to a error page
|
|
Helper::redirectToErrorPage($this->session);
|
|
}
|
|
|
|
if (
|
|
$this->meta['mode'] !== 'r' &&
|
|
$this->meta['mode'] !== 'rb' &&
|
|
$this->isLocalTmpFile === false &&
|
|
$this->size > 0 &&
|
|
$this->unencryptedSize > 0
|
|
) {
|
|
|
|
// only write keyfiles if it was a new file
|
|
if ($this->newFile === true) {
|
|
|
|
// Disable encryption proxy to prevent recursive calls
|
|
$proxyStatus = \OC_FileProxy::$enabled;
|
|
\OC_FileProxy::$enabled = false;
|
|
|
|
// Fetch user's public key
|
|
$this->publicKey = Keymanager::getPublicKey($this->rootView, $this->keyId);
|
|
|
|
// Check if OC sharing api is enabled
|
|
$sharingEnabled = \OCP\Share::isEnabled();
|
|
|
|
// Get all users sharing the file includes current user
|
|
$uniqueUserIds = $this->util->getSharingUsersArray($sharingEnabled, $this->relPath);
|
|
$checkedUserIds = $this->util->filterShareReadyUsers($uniqueUserIds);
|
|
|
|
// Fetch public keys for all sharing users
|
|
$publicKeys = Keymanager::getPublicKeys($this->rootView, $checkedUserIds['ready']);
|
|
|
|
// Encrypt enc key for all sharing users
|
|
$this->encKeyfiles = Crypt::multiKeyEncrypt($this->plainKey, $publicKeys);
|
|
|
|
// Save the new encrypted file key
|
|
Keymanager::setFileKey($this->rootView, $this->util, $this->relPath, $this->encKeyfiles['data']);
|
|
|
|
// Save the sharekeys
|
|
Keymanager::setShareKeys($this->rootView, $this->util, $this->relPath, $this->encKeyfiles['keys']);
|
|
|
|
// Re-enable proxy - our work is done
|
|
\OC_FileProxy::$enabled = $proxyStatus;
|
|
}
|
|
|
|
// we need to update the file info for the real file, not for the
|
|
// part file.
|
|
$path = Helper::stripPartialFileExtension($this->rawPath);
|
|
|
|
$fileInfo = array(
|
|
'mimetype' => $this->rootView->getMimeType($this->rawPath),
|
|
'encrypted' => true,
|
|
'unencrypted_size' => $this->unencryptedSize,
|
|
);
|
|
|
|
// if we write a part file we also store the unencrypted size for
|
|
// the part file so that it can be re-used later
|
|
$this->rootView->putFileInfo($this->rawPath, $fileInfo);
|
|
if ($path !== $this->rawPath) {
|
|
$this->rootView->putFileInfo($path, $fileInfo);
|
|
}
|
|
|
|
}
|
|
|
|
$result = fclose($this->handle);
|
|
|
|
if ($result === false) {
|
|
\OCP\Util::writeLog('Encryption library', 'Could not close stream, file could be corrupted', \OCP\Util::FATAL);
|
|
}
|
|
|
|
return $result;
|
|
|
|
}
|
|
|
|
}
|