nextcloud/apps/files_encryption/lib/keymanager.php

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<?php
/**
* ownCloud
*
* @author Bjoern Schiessle
* @copyright 2012 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 OCA\Encryption;
/**
* Class to manage storage and retrieval of encryption keys
* @note Where a method requires a view object, it's root must be '/'
*/
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class Keymanager {
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/**
* retrieve the ENCRYPTED private key from a user
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*
* @param \OC\Files\View $view
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* @param string $user
* @return string private key or false (hopefully)
* @note the key returned by this method must be decrypted before use
*/
public static function getPrivateKey(\OC\Files\View $view, $user) {
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$path = '/' . $user . '/' . 'files_encryption' . '/' . $user . '.private.key';
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$key = false;
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$proxyStatus = \OC_FileProxy::$enabled;
\OC_FileProxy::$enabled = false;
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if ($view->file_exists($path)) {
$key = $view->file_get_contents($path);
}
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\OC_FileProxy::$enabled = $proxyStatus;
return $key;
}
/**
* retrieve public key for a specified user
* @param \OC\Files\View $view
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* @param string $userId
* @return string public key or false
*/
public static function getPublicKey(\OC\Files\View $view, $userId) {
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$proxyStatus = \OC_FileProxy::$enabled;
\OC_FileProxy::$enabled = false;
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$result = $view->file_get_contents('/public-keys/' . $userId . '.public.key');
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\OC_FileProxy::$enabled = $proxyStatus;
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return $result;
}
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/**
* Retrieve a user's public and private key
* @param \OC\Files\View $view
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* @param string $userId
* @return array keys: privateKey, publicKey
*/
public static function getUserKeys(\OC\Files\View $view, $userId) {
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return array(
'publicKey' => self::getPublicKey($view, $userId),
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'privateKey' => self::getPrivateKey($view, $userId)
);
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}
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/**
* Retrieve public keys for given users
* @param \OC\Files\View $view
* @param array $userIds
* @return array of public keys for the specified users
*/
public static function getPublicKeys(\OC\Files\View $view, array $userIds) {
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$keys = array();
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foreach ($userIds as $userId) {
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$keys[$userId] = self::getPublicKey($view, $userId);
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}
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return $keys;
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}
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/**
* store file encryption key
*
* @param \OC\Files\View $view
* @param \OCA\Encryption\Util $util
* @param string $path relative path of the file, including filename
* @param string $catfile keyfile content
* @return bool true/false
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* @note The keyfile is not encrypted here. Client code must
* asymmetrically encrypt the keyfile before passing it to this method
*/
public static function setFileKey(\OC\Files\View $view, $util, $path, $catfile) {
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$proxyStatus = \OC_FileProxy::$enabled;
\OC_FileProxy::$enabled = false;
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list($owner, $filename) = $util->getUidAndFilename($path);
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// in case of system wide mount points the keys are stored directly in the data directory
if ($util->isSystemWideMountPoint($filename)) {
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$basePath = '/files_encryption/keyfiles';
} else {
$basePath = '/' . $owner . '/files_encryption/keyfiles';
}
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$targetPath = self::keySetPreparation($view, $filename, $basePath);
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// try reusing key file if part file
if (Helper::isPartialFilePath($targetPath)) {
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$result = $view->file_put_contents(
$basePath . '/' . Helper::stripPartialFileExtension($targetPath) . '.key', $catfile);
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} else {
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$result = $view->file_put_contents($basePath . '/' . $targetPath . '.key', $catfile);
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}
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\OC_FileProxy::$enabled = $proxyStatus;
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return $result;
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}
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/**
* retrieve keyfile for an encrypted file
* @param \OC\Files\View $view
* @param \OCA\Encryption\Util $util
* @param string|false $filePath
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* @internal param \OCA\Encryption\file $string name
* @return string file key or false
* @note The keyfile returned is asymmetrically encrypted. Decryption
* of the keyfile must be performed by client code
*/
public static function getFileKey($view, $util, $filePath) {
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list($owner, $filename) = $util->getUidAndFilename($filePath);
$filename = Helper::stripPartialFileExtension($filename);
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$filePath_f = ltrim($filename, '/');
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// in case of system wide mount points the keys are stored directly in the data directory
if ($util->isSystemWideMountPoint($filename)) {
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$keyfilePath = '/files_encryption/keyfiles/' . $filePath_f . '.key';
} else {
$keyfilePath = '/' . $owner . '/files_encryption/keyfiles/' . $filePath_f . '.key';
}
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$proxyStatus = \OC_FileProxy::$enabled;
\OC_FileProxy::$enabled = false;
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if ($view->file_exists($keyfilePath)) {
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$result = $view->file_get_contents($keyfilePath);
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} else {
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$result = false;
}
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\OC_FileProxy::$enabled = $proxyStatus;
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return $result;
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}
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/**
* Delete a keyfile
*
* @param \OC\Files\View $view
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* @param string $path path of the file the key belongs to
* @param string $userId the user to whom the file belongs
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* @return bool Outcome of unlink operation
* @note $path must be relative to data/user/files. e.g. mydoc.txt NOT
* /data/admin/files/mydoc.txt
*/
public static function deleteFileKey($view, $path, $userId=null) {
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$trimmed = ltrim($path, '/');
if ($trimmed === '') {
\OCP\Util::writeLog('Encryption library',
'Can\'t delete file-key empty path given!', \OCP\Util::ERROR);
return false;
}
if ($userId === null) {
$userId = Helper::getUser($path);
}
$util = new Util($view, $userId);
if($util->isSystemWideMountPoint($path)) {
$keyPath = '/files_encryption/keyfiles/' . $trimmed;
} else {
$keyPath = '/' . $userId . '/files_encryption/keyfiles/' . $trimmed;
}
$result = false;
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$fileExists = $view->file_exists('/' . $userId . '/files/' . $trimmed);
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if ($view->is_dir($keyPath) && !$fileExists) {
\OCP\Util::writeLog('files_encryption', 'deleteFileKey: delete file key: ' . $keyPath, \OCP\Util::DEBUG);
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$result = $view->unlink($keyPath);
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} elseif ($view->file_exists($keyPath . '.key') && !$fileExists) {
\OCP\Util::writeLog('files_encryption', 'deleteFileKey: delete file key: ' . $keyPath, \OCP\Util::DEBUG);
$result = $view->unlink($keyPath . '.key');
}
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if ($fileExists) {
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\OCP\Util::writeLog('Encryption library',
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'Did not delete the file key, file still exists: ' . '/' . $userId . '/files/' . $trimmed, \OCP\Util::ERROR);
} elseif (!$result) {
\OCP\Util::writeLog('Encryption library',
'Could not delete keyfile; does not exist: "' . $keyPath, \OCP\Util::ERROR);
}
return $result;
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}
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/**
* store private key from the user
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* @param string $key
* @return bool
* @note Encryption of the private key must be performed by client code
* as no encryption takes place here
*/
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public static function setPrivateKey($key) {
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$user = \OCP\User::getUser();
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$view = new \OC\Files\View('/' . $user . '/files_encryption');
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$proxyStatus = \OC_FileProxy::$enabled;
\OC_FileProxy::$enabled = false;
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if (!$view->file_exists('')) {
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$view->mkdir('');
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}
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$result = $view->file_put_contents($user . '.private.key', $key);
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\OC_FileProxy::$enabled = $proxyStatus;
return $result;
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}
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/**
* store share key
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*
* @param \OC\Files\View $view
* @param string $path where the share key is stored
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* @param string $shareKey
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* @return bool true/false
* @note The keyfile is not encrypted here. Client code must
* asymmetrically encrypt the keyfile before passing it to this method
*/
private static function setShareKey(\OC\Files\View $view, $path, $shareKey) {
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$proxyStatus = \OC_FileProxy::$enabled;
\OC_FileProxy::$enabled = false;
$result = $view->file_put_contents($path, $shareKey);
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\OC_FileProxy::$enabled = $proxyStatus;
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if (is_int($result) && $result > 0) {
return true;
} else {
return false;
}
}
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/**
* store multiple share keys for a single file
* @param \OC\Files\View $view
* @param \OCA\Encryption\Util $util
* @param string $path
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* @param array $shareKeys
* @return bool
*/
public static function setShareKeys(\OC\Files\View $view, $util, $path, array $shareKeys) {
// $shareKeys must be an array with the following format:
// [userId] => [encrypted key]
list($owner, $filename) = $util->getUidAndFilename($path);
// in case of system wide mount points the keys are stored directly in the data directory
if ($util->isSystemWideMountPoint($filename)) {
$basePath = '/files_encryption/share-keys';
} else {
$basePath = '/' . $owner . '/files_encryption/share-keys';
}
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$shareKeyPath = self::keySetPreparation($view, $filename, $basePath);
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$result = true;
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foreach ($shareKeys as $userId => $shareKey) {
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// try reusing key file if part file
if (Helper::isPartialFilePath($shareKeyPath)) {
$writePath = $basePath . '/' . Helper::stripPartialFileExtension($shareKeyPath) . '.' . $userId . '.shareKey';
} else {
$writePath = $basePath . '/' . $shareKeyPath . '.' . $userId . '.shareKey';
}
if (!self::setShareKey($view, $writePath, $shareKey)) {
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// If any of the keys are not set, flag false
$result = false;
}
}
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// Returns false if any of the keys weren't set
return $result;
}
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/**
* retrieve shareKey for an encrypted file
* @param \OC\Files\View $view
* @param string $userId
* @param \OCA\Encryption\Util $util
* @param string $filePath
* @return string file key or false
* @note The sharekey returned is encrypted. Decryption
* of the keyfile must be performed by client code
*/
public static function getShareKey(\OC\Files\View $view, $userId, $util, $filePath) {
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// try reusing key file if part file
$proxyStatus = \OC_FileProxy::$enabled;
\OC_FileProxy::$enabled = false;
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list($owner, $filename) = $util->getUidAndFilename($filePath);
$filename = Helper::stripPartialFileExtension($filename);
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// in case of system wide mount points the keys are stored directly in the data directory
if ($util->isSystemWideMountPoint($filename)) {
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$shareKeyPath = '/files_encryption/share-keys/' . $filename . '.' . $userId . '.shareKey';
} else {
$shareKeyPath = '/' . $owner . '/files_encryption/share-keys/' . $filename . '.' . $userId . '.shareKey';
}
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if ($view->file_exists($shareKeyPath)) {
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$result = $view->file_get_contents($shareKeyPath);
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} else {
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$result = false;
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}
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\OC_FileProxy::$enabled = $proxyStatus;
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return $result;
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}
/**
* delete all share keys of a given file
* @param \OC\Files\View $view
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* @param string $userId owner of the file
* @param string $filePath path to the file, relative to the owners file dir
*/
public static function delAllShareKeys($view, $userId, $filePath) {
$filePath = ltrim($filePath, '/');
if ($view->file_exists('/' . $userId . '/files/' . $filePath)) {
\OCP\Util::writeLog('Encryption library',
'File still exists, stop deleting share keys!', \OCP\Util::ERROR);
return false;
}
if ($filePath === '') {
\OCP\Util::writeLog('Encryption library',
'Can\'t delete share-keys empty path given!', \OCP\Util::ERROR);
return false;
}
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$util = new util($view, $userId);
if ($util->isSystemWideMountPoint($filePath)) {
$baseDir = '/files_encryption/share-keys/';
} else {
$baseDir = $userId . '/files_encryption/share-keys/';
}
$result = true;
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if ($view->is_dir($baseDir . $filePath)) {
\OCP\Util::writeLog('files_encryption', 'delAllShareKeys: delete share keys: ' . $baseDir . $filePath, \OCP\Util::DEBUG);
$result = $view->unlink($baseDir . $filePath);
} else {
$parentDir = dirname($baseDir . $filePath);
$filename = pathinfo($filePath, PATHINFO_BASENAME);
foreach($view->getDirectoryContent($parentDir) as $content) {
$path = $content['path'];
if (self::getFilenameFromShareKey($content['name']) === $filename) {
\OCP\Util::writeLog('files_encryption', 'dellAllShareKeys: delete share keys: ' . '/' . $userId . '/' . $path, \OCP\Util::DEBUG);
$result &= $view->unlink('/' . $userId . '/' . $path);
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}
}
}
return (bool)$result;
}
/**
* Delete a single user's shareKey for a single file
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*
* @param \OC\Files\View $view relative to data/
* @param array $userIds list of users we want to remove
* @param string $filename the owners name of the file for which we want to remove the users relative to data/user/files
* @param string $owner owner of the file
*/
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public static function delShareKey($view, $userIds, $filename, $owner) {
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$proxyStatus = \OC_FileProxy::$enabled;
\OC_FileProxy::$enabled = false;
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$util = new Util($view, $owner);
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if ($util->isSystemWideMountPoint($filename)) {
$shareKeyPath = \OC\Files\Filesystem::normalizePath('/files_encryption/share-keys/' . $filename);
} else {
$shareKeyPath = \OC\Files\Filesystem::normalizePath('/' . $owner . '/files_encryption/share-keys/' . $filename);
}
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if ($view->is_dir($shareKeyPath)) {
self::recursiveDelShareKeys($shareKeyPath, $userIds, $owner, $view);
} else {
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foreach ($userIds as $userId) {
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if ($userId === $owner && $view->file_exists('/' . $owner . '/files/' . $filename)) {
\OCP\Util::writeLog('files_encryption', 'Tried to delete owner key, but the file still exists!', \OCP\Util::FATAL);
continue;
}
$result = $view->unlink($shareKeyPath . '.' . $userId . '.shareKey');
\OCP\Util::writeLog('files_encryption', 'delShareKey: delete share key: ' . $shareKeyPath . '.' . $userId . '.shareKey' , \OCP\Util::DEBUG);
if (!$result) {
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\OCP\Util::writeLog('Encryption library',
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'Could not delete shareKey; does not exist: "' . $shareKeyPath . '.' . $userId
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. '.shareKey"', \OCP\Util::ERROR);
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}
}
}
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\OC_FileProxy::$enabled = $proxyStatus;
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}
/**
* recursively delete share keys from given users
*
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* @param string $dir directory
* @param array $userIds user ids for which the share keys should be deleted
* @param string $owner owner of the file
* @param \OC\Files\View $view view relative to data/
*/
private static function recursiveDelShareKeys($dir, $userIds, $owner, $view) {
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$dirContent = $view->opendir($dir);
$dirSlices = explode('/', ltrim($dir, '/'));
$realFileDir = '/' . $owner . '/files/' . implode('/', array_slice($dirSlices, 3)) . '/';
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if (is_resource($dirContent)) {
while (($file = readdir($dirContent)) !== false) {
if (!\OC\Files\Filesystem::isIgnoredDir($file)) {
if ($view->is_dir($dir . '/' . $file)) {
self::recursiveDelShareKeys($dir . '/' . $file, $userIds, $owner, $view);
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} else {
$realFile = $realFileDir . self::getFilenameFromShareKey($file);
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foreach ($userIds as $userId) {
if (preg_match("/(.*)." . $userId . ".shareKey/", $file)) {
if ($userId === $owner &&
$view->file_exists($realFile)) {
\OCP\Util::writeLog('files_encryption', 'original file still exists, keep owners share key!', \OCP\Util::ERROR);
continue;
}
\OCP\Util::writeLog('files_encryption', 'recursiveDelShareKey: delete share key: ' . $file, \OCP\Util::DEBUG);
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$view->unlink($dir . '/' . $file);
}
}
}
}
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}
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closedir($dirContent);
}
}
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/**
* Make preparations to vars and filesystem for saving a keyfile
* @param string|boolean $path
* @param string $basePath
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*/
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protected static function keySetPreparation(\OC\Files\View $view, $path, $basePath) {
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$targetPath = ltrim($path, '/');
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$path_parts = pathinfo($targetPath);
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// If the file resides within a subdirectory, create it
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if (
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isset($path_parts['dirname'])
&& !$view->file_exists($basePath . '/' . $path_parts['dirname'])
) {
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$sub_dirs = explode('/', $basePath . '/' . $path_parts['dirname']);
$dir = '';
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foreach ($sub_dirs as $sub_dir) {
$dir .= '/' . $sub_dir;
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if (!$view->is_dir($dir)) {
$view->mkdir($dir);
}
}
}
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return $targetPath;
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}
/**
* extract filename from share key name
* @param string $shareKey (filename.userid.sharekey)
* @return string|false filename or false
*/
protected static function getFilenameFromShareKey($shareKey) {
$parts = explode('.', $shareKey);
$filename = false;
if(count($parts) > 2) {
$filename = implode('.', array_slice($parts, 0, count($parts)-2));
}
return $filename;
}
}