nextcloud/apps/files_encryption/lib/proxy.php

<?php

/**
* ownCloud
*
* @author Sam Tuke, Robin Appelman
* @copyright 2012 Sam Tuke samtuke@owncloud.com, Robin Appelman 
* icewind1991@gmail.com
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
* License as published by the Free Software Foundation; either
* version 3 of the License, or any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU AFFERO GENERAL PUBLIC LICENSE for more details.
*
* You should have received a copy of the GNU Affero General Public
* License along with this library.  If not, see <http://www.gnu.org/licenses/>.
*
*/


/**
 * transparent encryption
 */

namespace OCA_Encryption;

class Proxy extends \OC_FileProxy {

	private static $blackList = null; //mimetypes blacklisted from encryption
	
	private static $enableEncryption = null;
	
	/**
	 * Check if a file requires encryption
	 * @param string $path
	 * @return bool
	 *
	 * Tests if encryption is enabled, and file is allowed by blacklists
	 */
	private static function shouldEncrypt( $path ) {
	
		if ( is_null( self::$enableEncryption ) ) {
		
			self::$enableEncryption = ( \OCP\Config::getAppValue( 'files_encryption', 'enable_encryption', 'true' ) == 'true' );
			
		}
		
		if( !self::$enableEncryption ) {
		
			return false;
			
		}
		
		if( is_null(self::$blackList ) ) {
		
			self::$blackList = explode(',', \OCP\Config::getAppValue( 'files_encryption','type_blacklist','jpg,png,jpeg,avi,mpg,mpeg,mkv,mp3,oga,ogv,ogg' ) );
			
		}
		
		if( Crypt::isEncryptedContent( $path ) ) {
		
			return true;
			
		}
		
		$extension = substr( $path, strrpos( $path,'.' ) +1 );
		
		if ( array_search( $extension, self::$blackList ) === false ){
		
			return true;
			
		}
		
		return false;
	}

	/**
	 * Check if a file is encrypted according to database file cache
	 * @param string $path
	 * @return bool
	 */
	private static function isEncrypted( $path ){
	
		// Fetch all file metadata from DB
		$metadata = \OC_FileCache_Cached::get( $path, '' );
		
		// Return encryption status
		return isset( $metadata['encrypted'] ) and ( bool )$metadata['encrypted'];
	
	}
	
	public function preFile_put_contents( $path, &$data ) {
		
		if ( self::shouldEncrypt( $path ) ) {
		
			if ( !is_resource( $data ) ) { //stream put contents should have been converter to fopen
			
				// Set the filesize for userland, before encrypting
				$size = strlen( $data );
				
				// Encrypt plain data and fetch key
				$encrypted = Crypt::symmetricEncryptFileContentKeyfile( $data, $_SESSION['enckey'] );
				
				// Replace plain content with encrypted content by reference
				$data = $encrypted['encrypted'];
				
				# TODO: check if file is in subdirectories, and if so, create those parent directories. Or else monitor creation of directories using hooks to ensure path will always exist (what about existing directories when encryption is enabled?)
				
				// Save keyfile for newly encrypted file in parallel directory
				Keymanager::setFileKey( \OCP\USER::getUser(), $path, $encrypted['key'] );
				
				// Update the file cache with file info
				\OC_FileCache::put( $path, array( 'encrypted'=>true, 'size' => $size ), '' );
				
			}
		}
	}
	
	public function postFile_get_contents( $path, $data ) {
	
		if ( Crypt::isEncryptedContent( $data ) ) {
		trigger_error('best');
			$cached = \OC_FileCache_Cached::get( $path, '' );
			
			$data = Crypt::symmetricDecryptFileContent( $data, $_SESSION['enckey'] );
		
		}
		
		return $data;
	}
	
	public function postFopen($path,&$result){
	
		if(!$result){
			return $result;
		}
		$meta=stream_get_meta_data($result);
		if(Crypt::isEncryptedContent($path)){
			fclose($result);
			$result=fopen('crypt://'.$path,$meta['mode']);
		}elseif(self::shouldEncrypt($path) and $meta['mode']!='r' and $meta['mode']!='rb'){
			if( \OC_Filesystem::file_exists( $path ) and \OC_Filesystem::filesize($path)>0){
				//first encrypt the target file so we don't end up with a half encrypted file
				\OCP\Util::writeLog('files_encryption','Decrypting '.$path.' before writing', \OCP\Util::DEBUG);
				$tmp=fopen('php://temp');
				\OCP\Files::streamCopy($result,$tmp);
				fclose($result);
				\OC_Filesystem::file_put_contents($path,$tmp);
				fclose($tmp);
			}
			$result=fopen('crypt://'.$path,$meta['mode']);
		}
		return $result;
	}

	public function postGetMimeType($path,$mime){
		if(Crypt::isEncryptedContent($path)){
			$mime = \OCP\Files::getMimeType('crypt://'.$path,'w');
		}
		return $mime;
	}

	public function postStat($path,$data){
		if(Crypt::isEncryptedContent($path)){
			$cached=  \OC_FileCache_Cached::get($path,'');
			$data['size']=$cached['size'];
		}
		return $data;
	}

	public function postFileSize($path,$size){
		if(Crypt::isEncryptedContent($path)){
			$cached = \OC_FileCache_Cached::get($path,'');
			return  $cached['size'];
		}else{
			return $size;
		}
	}
}