nextcloud/lib/private/files/stream/encryption.php

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<?php
/**
* ownCloud - Encryption stream wrapper
*
* @copyright (C) 2015 ownCloud, Inc.
*
* @author Bjoern Schiessle <schiessle@owncloud.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/>.
*/
namespace OC\Files\Stream;
use Icewind\Streams\Wrapper;
use OC\Encryption\Exceptions\EncryptionHeaderKeyExistsException;
class Encryption extends Wrapper {
/** @var \OC\Encryption\Util */
protected $util;
/** @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 $unencryptedBlockSize;
/** @var array */
protected $header;
/** @var string */
protected $fullPath;
/**
* 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
*
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* @var string
*/
protected $uid;
/** @var bool */
protected $readOnly;
/** @var bool */
protected $writeFlag;
/** @var array */
protected $expectedContextProperties;
public function __construct() {
$this->expectedContextProperties = array(
'source',
'storage',
'internalPath',
'fullPath',
'encryptionModule',
'header',
'uid',
'util',
'size',
'unencryptedSize',
'encryptionStorage'
);
}
/**
* 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
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* @param string $uid
* @param \OCP\Encryption\IEncryptionModule $encryptionModule
* @param \OC\Files\Storage\Storage $storage
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* @param \OC\Files\Storage\Wrapper\Encryption $encStorage
* @param \OC\Encryption\Util $util
* @param string $mode
* @param int $size
* @param int $unencryptedSize
* @return resource
*
* @throws \BadMethodCallException
*/
public static function wrap($source, $internalPath, $fullPath, array $header,
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$uid,
\OCP\Encryption\IEncryptionModule $encryptionModule,
\OC\Files\Storage\Storage $storage,
\OC\Files\Storage\Wrapper\Encryption $encStorage,
\OC\Encryption\Util $util,
$mode,
$size,
$unencryptedSize) {
$context = stream_context_create(array(
'ocencryption' => array(
'source' => $source,
'storage' => $storage,
'internalPath' => $internalPath,
'fullPath' => $fullPath,
'encryptionModule' => $encryptionModule,
'header' => $header,
'uid' => $uid,
'util' => $util,
'size' => $size,
'unencryptedSize' => $unencryptedSize,
'encryptionStorage' => $encStorage
)
));
return self::wrapSource($source, $mode, $context, 'ocencryption', 'OC\Files\Stream\Encryption');
}
/**
* add stream wrapper
*
* @param resource $source
* @param string $mode
* @param array $context
* @param string $protocol
* @param string $class
* @return resource
* @throws \BadMethodCallException
*/
protected static function wrapSource($source, $mode, $context, $protocol, $class) {
try {
stream_wrapper_register($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) {
$context = parent::loadContext($name);
foreach ($this->expectedContextProperties as $property) {
if (isset($context[$property])) {
$this->{$property} = $context[$property];
} else {
throw new \BadMethodCallException('Invalid context, "' . $property . '" options not set');
}
}
return $context;
}
public function stream_open($path, $mode, $options, &$opened_path) {
$this->loadContext('ocencryption');
$this->position = 0;
$this->cache = '';
$this->writeFlag = false;
$this->unencryptedBlockSize = $this->encryptionModule->getUnencryptedBlockSize();
if (
$mode === 'w'
|| $mode === 'w+'
|| $mode === 'wb'
|| $mode === 'wb+'
) {
// We're writing a new file so start write counter with 0 bytes
// TODO can we remove this completely?
//$this->unencryptedSize = 0;
//$this->size = 0;
$this->readOnly = false;
} else {
$this->readOnly = true;
}
$sharePath = $this->fullPath;
if (!$this->storage->file_exists($this->internalPath)) {
$sharePath = dirname($path);
}
$accessList = $this->util->getSharingUsersArray($sharePath);
$this->newHeader = $this->encryptionModule->begin($this->fullPath, $this->uid, $this->header, $accessList);
return true;
}
public function stream_read($count) {
$result = '';
// skip the header if we read the file from the beginning
if ($this->position === 0 && !empty($this->header)) {
parent::stream_read($this->util->getBlockSize());
}
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;
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// 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 $result;
}
public function stream_write($data) {
if ($this->position === 0) {
$this->writeHeader();
$this->size+=$this->util->getHeaderSize();
}
$length = 0;
// loop over $data to fit it in 6126 sized unencrypted blocks
while (strlen($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
$positionInFile = floor($this->position / $this->unencryptedBlockSize) *
$this->util->getBlockSize() + $this->util->getHeaderSize();
$resultFseek = parent::stream_seek($positionInFile);
// only allow writes on seekable streams, or at the end of the encrypted stream
if (!($this->readOnly) && ($resultFseek || $positionInFile === $this->size)) {
// switch the writeFlag so flush() will write the block
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$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 = '';
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// 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:
if ($offset < $this->unencryptedSize && $offset >= 0) {
$newPosition = $offset;
}
break;
case SEEK_CUR:
if ($offset >= 0) {
$newPosition = $offset + $this->position;
}
break;
case SEEK_END:
if ($this->unencryptedSize + $offset >= 0) {
$newPosition = $this->unencryptedSize + $offset;
}
break;
default:
return $return;
}
$newFilePosition = floor($newPosition / $this->unencryptedBlockSize)
* $this->util->getBlockSize() + $this->util->getHeaderSize();
if (parent::stream_seek($newFilePosition)) {
$this->flush();
$this->position = $newPosition;
$return = true;
}
return $return;
}
public function stream_close() {
$this->flush();
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$remainingData = $this->encryptionModule->end($this->fullPath);
if ($this->readOnly === false) {
if(!empty($remainingData)) {
parent::stream_write($remainingData);
}
$this->encryptionStorage->updateUnencryptedSize($this->fullPath, $this->unencryptedSize);
}
return parent::stream_close();
}
/**
* write block to file
*/
protected function flush() {
// write to disk only when writeFlag was set to 1
if ($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
$encrypted = $this->encryptionModule->encrypt($this->cache);
parent::stream_write($encrypted);
$this->writeFlag = false;
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$this->size = max($this->size, parent::stream_tell());
}
// always empty the cache (otherwise readCache() will not fill it with the new block)
$this->cache = '';
}
/**
* read block to file
*/
protected function readCache() {
// cache should always be empty string when this function is called
// don't try to fill the cache when trying to write at the end of the unencrypted file when it coincides with new block
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if ($this->cache === '' && !($this->position === $this->unencryptedSize && ($this->position % $this->unencryptedBlockSize) === 0)) {
// Get the data from the file handle
$data = parent::stream_read($this->util->getBlockSize());
$this->cache = $this->encryptionModule->decrypt($data);
}
}
/**
* write header at beginning of encrypted file
*
* @return integer
* @throws EncryptionHeaderKeyExistsException if header key is already in use
*/
private function writeHeader() {
$header = $this->util->createHeader($this->newHeader, $this->encryptionModule);
return parent::stream_write($header);
}
}