nextcloud/apps/files_encryption/lib/keymanager.php

<?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;

/**
 * @brief Class to manage storage and retrieval of encryption keys
 * @note Where a method requires a view object, it's root must be '/'
 */
class Keymanager
{

	/**
	 * @brief retrieve the ENCRYPTED private key from a user
	 *
	 * @param \OC_FilesystemView $view
	 * @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_FilesystemView $view, $user ) {

		$path = '/' . $user . '/' . 'files_encryption' . '/' . $user . '.private.key';

		$proxyStatus = \OC_FileProxy::$enabled;
		\OC_FileProxy::$enabled = false;

		$key = $view->file_get_contents( $path );

		\OC_FileProxy::$enabled = $proxyStatus;

		return $key;
	}

	/**
	 * @brief retrieve public key for a specified user
	 * @param \OC_FilesystemView $view
	 * @param $userId
	 * @return string public key or false
	 */
	public static function getPublicKey( \OC_FilesystemView $view, $userId ) {

		$proxyStatus = \OC_FileProxy::$enabled;
		\OC_FileProxy::$enabled = false;

		$result = $view->file_get_contents( '/public-keys/' . $userId . '.public.key' );

		\OC_FileProxy::$enabled = $proxyStatus;

		return $result;

	}

	/**
	 * @brief Retrieve a user's public and private key
	 * @param \OC_FilesystemView $view
	 * @param $userId
	 * @return array keys: privateKey, publicKey
	 */
	public static function getUserKeys( \OC_FilesystemView $view, $userId ) {

		return array(
			'publicKey' => self::getPublicKey( $view, $userId )
		, 'privateKey' => self::getPrivateKey( $view, $userId )
		);

	}

	/**
	 * @brief Retrieve public keys for given users
	 * @param \OC_FilesystemView $view
	 * @param array $userIds
	 * @return array of public keys for the specified users
	 */
	public static function getPublicKeys( \OC_FilesystemView $view, array $userIds ) {

		$keys = array();

		foreach ( $userIds as $userId ) {

			$keys[$userId] = self::getPublicKey( $view, $userId );

		}

		return $keys;

	}

	/**
	 * @brief store file encryption key
	 *
	 * @param \OC_FilesystemView $view
	 * @param string $path relative path of the file, including filename
	 * @param $userId
	 * @param $catfile
	 * @internal param string $key
	 * @return bool true/false
	 * @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_FilesystemView $view, $path, $userId, $catfile ) {

		$proxyStatus = \OC_FileProxy::$enabled;
		\OC_FileProxy::$enabled = false;

		//here we need the currently logged in user, while userId can be a different user
		$util = new Util( $view, \OCP\User::getUser() );
		list( $owner, $filename ) = $util->getUidAndFilename( $path );

		$basePath = '/' . $owner . '/files_encryption/keyfiles';

		$targetPath = self::keySetPreparation( $view, $filename, $basePath, $owner );

		if ( !$view->is_dir( $basePath . '/' . $targetPath ) ) {

			// create all parent folders
			$info = pathinfo( $basePath . '/' . $targetPath );
			$keyfileFolderName = $view->getLocalFolder( $info['dirname'] );

			if ( !file_exists( $keyfileFolderName ) ) {

				mkdir( $keyfileFolderName, 0750, true );

			}
		}

		// try reusing key file if part file
		if ( self::isPartialFilePath( $targetPath ) ) {

			$result = $view->file_put_contents( $basePath . '/' . self::fixPartialFilePath( $targetPath ) . '.key', $catfile );

		} else {

			$result = $view->file_put_contents( $basePath . '/' . $targetPath . '.key', $catfile );

		}

		\OC_FileProxy::$enabled = $proxyStatus;

		return $result;

	}

	/**
	 * @brief Remove .path extension from a file path
	 * @param string $path Path that may identify a .part file
	 * @return string File path without .part extension
	 * @note this is needed for reusing keys
	 */
	public static function fixPartialFilePath( $path ) {

		if ( preg_match( '/\.part$/', $path ) ) {

			$newLength = strlen( $path ) - 5;
			$fPath = substr( $path, 0, $newLength );

			return $fPath;

		} else {

			return $path;

		}

	}

	/**
	 * @brief Check if a path is a .part file
	 * @param string $path Path that may identify a .part file
	 * @return bool
	 */
	public static function isPartialFilePath( $path ) {

		if ( preg_match( '/\.part$/', $path ) ) {

			return true;

		} else {

			return false;

		}

	}

	/**
	 * @brief retrieve keyfile for an encrypted file
	 * @param \OC_FilesystemView $view
	 * @param $userId
	 * @param $filePath
	 * @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( \OC_FilesystemView $view, $userId, $filePath ) {

		// try reusing key file if part file
		if ( self::isPartialFilePath( $filePath ) ) {

			$result = self::getFileKey( $view, $userId, self::fixPartialFilePath( $filePath ) );

			if ( $result ) {

				return $result;

			}

		}

		$util = new Util( $view, \OCP\User::getUser() );

		list( $owner, $filename ) = $util->getUidAndFilename( $filePath );
		$filePath_f = ltrim( $filename, '/' );

		$keyfilePath = '/' . $owner . '/files_encryption/keyfiles/' . $filePath_f . '.key';

		$proxyStatus = \OC_FileProxy::$enabled;
		\OC_FileProxy::$enabled = false;

		if ( $view->file_exists( $keyfilePath ) ) {

			$result = $view->file_get_contents( $keyfilePath );

		} else {

			$result = false;

		}

		\OC_FileProxy::$enabled = $proxyStatus;

		return $result;

	}

	/**
	 * @brief Delete a keyfile
	 *
	 * @param \OC_FilesystemView $view
	 * @param string $userId username
	 * @param string $path path of the file the key belongs to
	 * @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( \OC_FilesystemView $view, $userId, $path ) {

		$trimmed = ltrim( $path, '/' );
		$keyPath = '/' . $userId . '/files_encryption/keyfiles/' . $trimmed;

		$result = false;

		if ( $view->is_dir( $keyPath ) ) {

			$result = $view->unlink( $keyPath );

		} else if ( $view->file_exists( $keyPath . '.key' ) ) {

			$result = $view->unlink( $keyPath . '.key' );

		}

		if ( !$result ) {

			\OC_Log::write( 'Encryption library', 'Could not delete keyfile; does not exist: "' . $keyPath, \OC_Log::ERROR );

		}

		return $result;

	}

	/**
	 * @brief store private key from the user
	 * @param string $key
	 * @return bool
	 * @note Encryption of the private key must be performed by client code
	 * as no encryption takes place here
	 */
	public static function setPrivateKey( $key ) {

		$user = \OCP\User::getUser();

		$view = new \OC_FilesystemView( '/' . $user . '/files_encryption' );

		$proxyStatus = \OC_FileProxy::$enabled;
		\OC_FileProxy::$enabled = false;

		if ( !$view->file_exists( '' ) )
			$view->mkdir( '' );

		$result = $view->file_put_contents( $user . '.private.key', $key );

		\OC_FileProxy::$enabled = $proxyStatus;

		return $result;

	}

	/**
	 * @brief store share key
	 *
	 * @param \OC_FilesystemView $view
	 * @param string $path relative path of the file, including filename
	 * @param $userId
	 * @param $shareKey
	 * @internal param string $key
	 * @internal param string $dbClassName
	 * @return bool true/false
	 * @note The keyfile is not encrypted here. Client code must
	 * asymmetrically encrypt the keyfile before passing it to this method
	 */
	public static function setShareKey( \OC_FilesystemView $view, $path, $userId, $shareKey ) {

		// Here we need the currently logged in user, while userId can be a different user
		$util = new Util( $view, \OCP\User::getUser() );

		list( $owner, $filename ) = $util->getUidAndFilename( $path );

		$basePath = '/' . $owner . '/files_encryption/share-keys';

		$shareKeyPath = self::keySetPreparation( $view, $filename, $basePath, $owner );

		// try reusing key file if part file
		if ( self::isPartialFilePath( $shareKeyPath ) ) {

			$writePath = $basePath . '/' . self::fixPartialFilePath( $shareKeyPath ) . '.' . $userId . '.shareKey';

		} else {

			$writePath = $basePath . '/' . $shareKeyPath . '.' . $userId . '.shareKey';

		}

		$proxyStatus = \OC_FileProxy::$enabled;
		\OC_FileProxy::$enabled = false;

		$result = $view->file_put_contents( $writePath, $shareKey );

		\OC_FileProxy::$enabled = $proxyStatus;

		if (
			is_int( $result )
			&& $result > 0
		) {

			return true;

		} else {

			return false;

		}

	}

	/**
	 * @brief store multiple share keys for a single file
	 * @param \OC_FilesystemView $view
	 * @param $path
	 * @param array $shareKeys
	 * @return bool
	 */
	public static function setShareKeys( \OC_FilesystemView $view, $path, array $shareKeys ) {

		// $shareKeys must be  an array with the following format:
		// [userId] => [encrypted key]

		$result = true;

		foreach ( $shareKeys as $userId => $shareKey ) {

			if ( !self::setShareKey( $view, $path, $userId, $shareKey ) ) {

				// If any of the keys are not set, flag false
				$result = false;

			}

		}

		// Returns false if any of the keys weren't set
		return $result;

	}

	/**
	 * @brief retrieve shareKey for an encrypted file
	 * @param \OC_FilesystemView $view
	 * @param string $userId
	 * @param string $filePath
	 * @internal param \OCA\Encryption\file $string name
	 * @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_FilesystemView $view, $userId, $filePath ) {

		// try reusing key file if part file
		if ( self::isPartialFilePath( $filePath ) ) {

			$result = self::getShareKey( $view, $userId, self::fixPartialFilePath( $filePath ) );

			if ( $result ) {

				return $result;

			}

		}

		$proxyStatus = \OC_FileProxy::$enabled;
		\OC_FileProxy::$enabled = false;

		//here we need the currently logged in user, while userId can be a different user
		$util = new Util( $view, \OCP\User::getUser() );

		list( $owner, $filename ) = $util->getUidAndFilename( $filePath );
		$shareKeyPath = \OC\Files\Filesystem::normalizePath( '/' . $owner . '/files_encryption/share-keys/' . $filename . '.' . $userId . '.shareKey' );

		if ( $view->file_exists( $shareKeyPath ) ) {

			$result = $view->file_get_contents( $shareKeyPath );

		} else {

			$result = false;

		}

		\OC_FileProxy::$enabled = $proxyStatus;

		return $result;

	}

	/**
	 * @brief delete all share keys of a given file
	 * @param \OC_FilesystemView $view
	 * @param string $userId owner of the file
	 * @param string $filePath path to the file, relative to the owners file dir
	 */
	public static function delAllShareKeys( \OC_FilesystemView $view, $userId, $filePath ) {

		if ( $view->is_dir( $userId . '/files/' . $filePath ) ) {
			$view->unlink( $userId . '/files_encryption/share-keys/' . $filePath );
		} else {
			$localKeyPath = $view->getLocalFile( $userId . '/files_encryption/share-keys/' . $filePath );
			$matches = glob( preg_quote( $localKeyPath ) . '*.shareKey' );
			foreach ( $matches as $ma ) {
				$result = unlink( $ma );
				if ( !$result ) {
					\OC_Log::write( 'Encryption library', 'Keyfile or shareKey could not be deleted for file "' . $filePath . '"', \OC_Log::ERROR );
				}
			}
		}
	}

	/**
	 * @brief Delete a single user's shareKey for a single file
	 */
	public static function delShareKey( \OC_FilesystemView $view, $userIds, $filePath ) {

		$proxyStatus = \OC_FileProxy::$enabled;
		\OC_FileProxy::$enabled = false;

		//here we need the currently logged in user, while userId can be a different user
		$util = new Util( $view, \OCP\User::getUser() );

		list( $owner, $filename ) = $util->getUidAndFilename( $filePath );

		$shareKeyPath = \OC\Files\Filesystem::normalizePath( '/' . $owner . '/files_encryption/share-keys/' . $filename );

		if ( $view->is_dir( $shareKeyPath ) ) {

			$localPath = \OC\Files\Filesystem::normalizePath( $view->getLocalFolder( $shareKeyPath ) );
			self::recursiveDelShareKeys( $localPath, $userIds );

		} else {

			foreach ( $userIds as $userId ) {

				if ( !$view->unlink( $shareKeyPath . '.' . $userId . '.shareKey' ) ) {
					\OC_Log::write( 'Encryption library', 'Could not delete shareKey; does not exist: "' . $shareKeyPath . '.' . $userId . '.shareKey"', \OC_Log::ERROR );
				}

			}
		}

		\OC_FileProxy::$enabled = $proxyStatus;
	}

	/**
	 * @brief recursively delete share keys from given users
	 *
	 * @param string $dir directory
	 * @param array $userIds user ids for which the share keys should be deleted
	 */
	private static function recursiveDelShareKeys( $dir, $userIds ) {
		foreach ( $userIds as $userId ) {
			$matches = glob( preg_quote( $dir ) . '/*' . preg_quote( '.' . $userId . '.shareKey' ) );
		}
		/** @var $matches array */
		foreach ( $matches as $ma ) {
			if ( !unlink( $ma ) ) {
				\OC_Log::write( 'Encryption library', 'Could not delete shareKey; does not exist: "' . $ma . '"', \OC_Log::ERROR );
			}
		}
		$subdirs = $directories = glob( preg_quote( $dir ) . '/*', GLOB_ONLYDIR );
		foreach ( $subdirs as $subdir ) {
			self::recursiveDelShareKeys( $subdir, $userIds );
		}
	}

	/**
	 * @brief Make preparations to vars and filesystem for saving a keyfile
	 */
	public static function keySetPreparation( \OC_FilesystemView $view, $path, $basePath, $userId ) {

		$targetPath = ltrim( $path, '/' );

		$path_parts = pathinfo( $targetPath );

		// If the file resides within a subdirectory, create it
		if (
			isset( $path_parts['dirname'] )
			&& !$view->file_exists( $basePath . '/' . $path_parts['dirname'] )
		) {
			$sub_dirs = explode( DIRECTORY_SEPARATOR, $basePath . '/' . $path_parts['dirname'] );
			$dir = '';
			foreach ( $sub_dirs as $sub_dir ) {
				$dir .= '/' . $sub_dir;
				if ( !$view->is_dir( $dir ) ) {
					$view->mkdir( $dir );
				}
			}
		}

		return $targetPath;

	}
}