lib/private/Files/Stream/Encryption.php
<?php
/**
* @author Björn Schießle <bjoern@schiessle.org>
* @author jknockaert <jasper@knockaert.nl>
* @author Lukas Reschke <lukas@statuscode.ch>
* @author Roeland Jago Douma <rullzer@owncloud.com>
* @author Thomas Müller <thomas.mueller@tmit.eu>
* @author Vincent Petry <pvince81@owncloud.com>
*
* @copyright Copyright (c) 2018, ownCloud GmbH
* @license AGPL-3.0
*
* This code is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program 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, version 3,
* along with this program. If not, see <http://www.gnu.org/licenses/>
*
*/
namespace OC\Files\Stream;
use Icewind\Streams\Wrapper;
use OC\Encryption\Exceptions\EncryptionHeaderKeyExistsException;
class Encryption extends Wrapper {
/** @var \OC\Encryption\Util */
protected $util;
/** @var \OC\Encryption\File */
protected $file;
/** @var \OCP\Encryption\IEncryptionModule */
protected $encryptionModule;
/** @var \OC\Files\Storage\Storage */
protected $storage;
/** @var \OC\Files\Storage\Wrapper\Encryption */
protected $encryptionStorage;
/** @var string */
protected $internalPath;
/** @var string */
protected $cache;
/** @var integer */
protected $size;
/** @var integer */
protected $position;
/** @var integer */
protected $unencryptedSize;
/** @var integer */
protected $headerSize;
/** @var integer */
protected $unencryptedBlockSize;
/** @var array */
protected $header;
/** @var string */
protected $fullPath;
/** @var bool */
protected $signed;
/**
* header data returned by the encryption module, will be written to the file
* in case of a write operation
*
* @var array
*/
protected $newHeader;
/**
* user who perform the read/write operation null for public access
*
* @var string
*/
protected $uid;
/** @var bool */
protected $readOnly;
/** @var bool */
protected $writeFlag;
/** @var array */
protected $expectedContextProperties;
public function __construct() {
$this->expectedContextProperties = [
'source',
'storage',
'internalPath',
'fullPath',
'encryptionModule',
'header',
'uid',
'file',
'util',
'size',
'unencryptedSize',
'encryptionStorage',
'headerSize',
'signed',
'sourceFileOfRename'
];
}
/**
* Wraps a stream with the provided callbacks
*
* @param resource $source
* @param string $internalPath relative to mount point
* @param string $fullPath relative to data/
* @param array $header
* @param string $uid
* @param \OCP\Encryption\IEncryptionModule $encryptionModule
* @param \OC\Files\Storage\Storage $storage
* @param \OC\Files\Storage\Wrapper\Encryption $encStorage
* @param \OC\Encryption\Util $util
* @param \OC\Encryption\File $file
* @param string $mode
* @param int $size
* @param int $unencryptedSize
* @param int $headerSize
* @param bool $signed
* @param null|string $sourceFileOfRename
* @param string $wrapper stream wrapper class
* @return resource
*
* @throws \BadMethodCallException
*/
public static function wrap(
$source,
$internalPath,
$fullPath,
array $header,
$uid,
\OCP\Encryption\IEncryptionModule $encryptionModule,
\OC\Files\Storage\Storage $storage,
\OC\Files\Storage\Wrapper\Encryption $encStorage,
\OC\Encryption\Util $util,
\OC\Encryption\File $file,
$mode,
$size,
$unencryptedSize,
$headerSize,
$signed,
$sourceFileOfRename = null,
$wrapper = 'OC\Files\Stream\Encryption'
) {
$context = \stream_context_create([
'ocencryption' => [
'source' => $source,
'storage' => $storage,
'internalPath' => $internalPath,
'fullPath' => $fullPath,
'encryptionModule' => $encryptionModule,
'header' => $header,
'uid' => $uid,
'util' => $util,
'file' => $file,
'size' => $size,
'unencryptedSize' => $unencryptedSize,
'encryptionStorage' => $encStorage,
'headerSize' => $headerSize,
'signed' => $signed,
'sourceFileOfRename' => $sourceFileOfRename
]
]);
return self::wrapSource($source, $context, 'ocencryption', $wrapper, $mode);
}
/**
* add stream wrapper
*
* @param resource $source
* @param string $mode
* @param resource $context
* @param string $protocol
* @param string $class
* @return resource
* @throws \BadMethodCallException
*/
protected static function wrapSource($source, $context = [], $protocol = null, $class = null, $mode = 'r+') {
try {
\stream_wrapper_register($protocol, $class);
if (@\rewinddir($source) === false) {
$wrapped = \fopen($protocol . '://', $mode, false, $context);
} else {
$wrapped = \opendir($protocol . '://', $context);
}
} catch (\BadMethodCallException $e) {
\stream_wrapper_unregister($protocol);
throw $e;
}
\stream_wrapper_unregister($protocol);
return $wrapped;
}
/**
* Load the source from the stream context and return the context options
*
* @param string $name
* @return array
* @throws \BadMethodCallException
*/
protected function loadContext($name = null) {
$context = parent::loadContext($name);
foreach ($this->expectedContextProperties as $property) {
if (\array_key_exists($property, $context)) {
$this->{$property} = $context[$property];
} else {
throw new \BadMethodCallException('Invalid context, "' . $property . '" options not set');
}
}
return $context;
}
public function stream_open($path, $mode, $options, &$opened_path) {
$context = $this->loadContext('ocencryption');
$this->position = 0;
$this->cache = '';
$this->writeFlag = false;
if (
$mode === 'w'
|| $mode === 'w+'
|| $mode === 'wb'
|| $mode === 'wb+'
|| $mode === 'r+'
|| $mode === 'rb+'
) {
$this->readOnly = false;
} else {
$this->readOnly = true;
}
$sharePath = $this->fullPath;
if (!$this->storage->file_exists($this->internalPath)) {
$sharePath = \dirname($sharePath);
}
$accessList = $this->file->getAccessList($sharePath);
$this->newHeader = $this->encryptionModule->begin($this->fullPath, $this->uid, $mode, $this->header, $accessList, $context['sourceFileOfRename']);
$this->unencryptedBlockSize = $this->encryptionModule->getUnencryptedBlockSize($this->signed);
if (
$mode === 'w'
|| $mode === 'w+'
|| $mode === 'wb'
|| $mode === 'wb+'
) {
// We're writing a new file so start write counter with 0 bytes
$this->unencryptedSize = 0;
$this->writeHeader();
$this->headerSize = $this->util->getHeaderSize();
$this->size = $this->headerSize;
} else {
$this->skipHeader();
}
return true;
}
public function stream_eof() {
return $this->position >= $this->unencryptedSize;
}
public function stream_read($count) {
$result = '';
$count = \min($count, $this->unencryptedSize - $this->position);
while ($count > 0) {
$remainingLength = $count;
// update the cache of the current block
$this->readCache();
// determine the relative position in the current block
$blockPosition = ($this->position % $this->unencryptedBlockSize);
// if entire read inside current block then only position needs to be updated
if ($remainingLength < ($this->unencryptedBlockSize - $blockPosition)) {
$result .= \substr($this->cache, $blockPosition, $remainingLength);
$this->position += $remainingLength;
$count = 0;
// otherwise remainder of current block is fetched, the block is flushed and the position updated
} else {
$result .= \substr($this->cache, $blockPosition);
$this->flush();
$this->position += ($this->unencryptedBlockSize - $blockPosition);
$count -= ($this->unencryptedBlockSize - $blockPosition);
}
}
return $result;
}
/**
* stream_read wrapper to read a block of the requested size
* There is a problem with the underlying php functions not returning the requested amount of data in any case.
* Thus, this function will call the read mechanism of its parent until it has read the correct amount.
*/
private function stream_read_block($blockSize) {
$remaining = $blockSize;
$data = "";
do {
$chunk = parent::stream_read($remaining);
$chunk_len = \strlen($chunk);
$data .= $chunk;
$remaining -= $chunk_len;
} while (($remaining > 0) && ($chunk_len > 0));
return $data;
}
public function stream_write($data) {
$length = 0;
// loop over $data to fit it in 6126 sized unencrypted blocks
while (isset($data[0])) {
$remainingLength = \strlen($data);
// set the cache to the current 6126 block
$this->readCache();
// for seekable streams the pointer is moved back to the beginning of the encrypted block
// flush will start writing there when the position moves to another block
$positionInFile = (int)\floor($this->position / $this->unencryptedBlockSize) *
$this->util->getBlockSize() + $this->headerSize;
$resultFseek = $this->parentStreamSeek($positionInFile);
// only allow writes on seekable streams, or at the end of the encrypted stream
if (!($this->readOnly) && ($resultFseek || $positionInFile === $this->size)) {
// switch the writeFlag so flush() will write the block
$this->writeFlag = true;
// determine the relative position in the current block
$blockPosition = ($this->position % $this->unencryptedBlockSize);
// check if $data fits in current block
// if so, overwrite existing data (if any)
// update position and liberate $data
if ($remainingLength < ($this->unencryptedBlockSize - $blockPosition)) {
$this->cache = \substr($this->cache, 0, $blockPosition)
. $data . \substr($this->cache, $blockPosition + $remainingLength);
$this->position += $remainingLength;
$length += $remainingLength;
$data = '';
// if $data doesn't fit the current block, the fill the current block and reiterate
// after the block is filled, it is flushed and $data is updatedxxx
} else {
$this->cache = \substr($this->cache, 0, $blockPosition) .
\substr($data, 0, $this->unencryptedBlockSize - $blockPosition);
$this->flush();
$this->position += ($this->unencryptedBlockSize - $blockPosition);
$length += ($this->unencryptedBlockSize - $blockPosition);
$data = \substr($data, $this->unencryptedBlockSize - $blockPosition);
}
} else {
$data = '';
}
$this->unencryptedSize = \max($this->unencryptedSize, $this->position);
}
return $length;
}
public function stream_tell() {
return $this->position;
}
public function stream_seek($offset, $whence = SEEK_SET) {
$return = false;
switch ($whence) {
case SEEK_SET:
$newPosition = $offset;
break;
case SEEK_CUR:
$newPosition = $this->position + $offset;
break;
case SEEK_END:
$newPosition = $this->unencryptedSize + $offset;
break;
default:
return $return;
}
if ($newPosition > $this->unencryptedSize || $newPosition < 0) {
return $return;
}
$newFilePosition = \floor($newPosition / $this->unencryptedBlockSize)
* $this->util->getBlockSize() + $this->headerSize;
$oldFilePosition = parent::stream_tell();
if ($this->parentStreamSeek($newFilePosition)) {
$this->parentStreamSeek($oldFilePosition);
$this->flush();
$this->parentStreamSeek($newFilePosition);
$this->position = $newPosition;
$return = true;
}
return $return;
}
public function stream_close() {
$this->flush('end');
$position = (int)\floor($this->position/$this->unencryptedBlockSize);
$remainingData = $this->encryptionModule->end($this->fullPath, $position . 'end');
if ($this->readOnly === false) {
if (!empty($remainingData)) {
parent::stream_write($remainingData);
}
$this->encryptionStorage->updateUnencryptedSize($this->fullPath, $this->unencryptedSize);
}
return parent::stream_close();
}
/**
* write block to file
* @param string $positionPrefix
*/
protected function flush($positionPrefix = '') {
// write to disk only when writeFlag was set to 1
if ($this->writeFlag) {
// Disable the file proxies so that encryption is not
// automatically attempted when the file is written to disk -
// we are handling that separately here and we don't want to
// get into an infinite loop
$position = (int)\floor($this->position/$this->unencryptedBlockSize);
$encrypted = $this->encryptionModule->encrypt($this->cache, $position . $positionPrefix);
$bytesWritten = parent::stream_write($encrypted);
$this->writeFlag = false;
// Check whether the write concerns the last block
// If so then update the encrypted filesize
// Note that the unencrypted pointer and filesize are NOT yet updated when flush() is called
// We recalculate the encrypted filesize as we do not know the context of calling flush()
$completeBlocksInFile=(int)\floor($this->unencryptedSize/$this->unencryptedBlockSize);
if ($completeBlocksInFile === (int)\floor($this->position/$this->unencryptedBlockSize)) {
$this->size = $this->util->getBlockSize() * $completeBlocksInFile;
$this->size += $bytesWritten;
$this->size += $this->headerSize;
}
}
// always empty the cache (otherwise readCache() will not fill it with the new block)
$this->cache = '';
}
/**
* read block to file
*/
protected function readCache() {
// cache should always be empty string when this function is called
// don't try to fill the cache when trying to write at the end of the unencrypted file when it coincides with new block
if ($this->cache === '' && !($this->position === $this->unencryptedSize && ($this->position % $this->unencryptedBlockSize) === 0)) {
// Get the data from the file handle
$data = $this->stream_read_block($this->util->getBlockSize());
$this->cache = $this->encryptionModule->decrypt($data, $this->getPosition());
}
}
public function getPosition() {
$blockPosition = (int)\floor($this->position/$this->unencryptedBlockSize);
$numberOfChunks = (int)($this->unencryptedSize / $this->unencryptedBlockSize);
if ($numberOfChunks === $blockPosition) {
$blockPosition .= 'end';
}
return $blockPosition;
}
/**
* write header at beginning of encrypted file
*
* @return integer
* @throws EncryptionHeaderKeyExistsException if header key is already in use
*/
protected function writeHeader() {
$header = $this->util->createHeader($this->newHeader, $this->encryptionModule);
return parent::stream_write($header);
}
/**
* read first block to skip the header
*/
protected function skipHeader() {
$this->stream_read_block($this->headerSize);
}
/**
* call stream_seek() from parent class
*
* @param integer $position
* @return bool
*/
protected function parentStreamSeek($position) {
return parent::stream_seek($position);
}
/**
* @param string $path
* @param array $options
* @return bool
*/
public function dir_opendir($path, $options) {
return false;
}
}