nextcloud/apps/files_encryption/hooks/hooks.php

<?php

/**
 * ownCloud
 *
 * @author Sam Tuke
 * @copyright 2012 Sam Tuke samtuke@owncloud.org
 *
 * 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;

use OC\Files\Filesystem;

/**
 * Class for hook specific logic
 */
class Hooks {

	// TODO: use passphrase for encrypting private key that is separate to 
	// the login password

	/**
	 * @brief Startup encryption backend upon user login
	 * @note This method should never be called for users using client side encryption
	 */
	public static function login( $params ) {
	
		// Manually initialise Filesystem{} singleton with correct 
		// fake root path, in order to avoid fatal webdav errors
        // NOTE: disabled because this give errors on webdav!
		//\OC\Files\Filesystem::init( $params['uid'], '/' . 'files' . '/' );
	
		$view = new \OC_FilesystemView( '/' );

		$util = new Util( $view, $params['uid'] );
		
		// Check files_encryption infrastructure is ready for action
		if ( ! $util->ready() ) {
			
			\OC_Log::write( 'Encryption library', 'User account "' . $params['uid'] . '" is not ready for encryption; configuration started', \OC_Log::DEBUG );
			
			if(!$util->setupServerSide( $params['password'] )) {
                return false;
            }

		}
	
		\OC_FileProxy::$enabled = false;
		
		$encryptedKey = Keymanager::getPrivateKey( $view, $params['uid'] );
		
		\OC_FileProxy::$enabled = true;
		
		$privateKey = Crypt::symmetricDecryptFileContent( $encryptedKey, $params['password'] );
		
		$session = new Session( $view );
		
		$session->setPrivateKey( $privateKey, $params['uid'] );
		
		// Check if first-run file migration has already been performed
		$migrationCompleted = $util->getMigrationStatus();
		
		// If migration not yet done
		if ( ! $migrationCompleted ) {
		
			$view1 = new \OC_FilesystemView( '/' . $params['uid'] );
			
			// Set legacy encryption key if it exists, to support 
			// depreciated encryption system
			if ( 
				$view1->file_exists( 'encryption.key' )
				&& $encLegacyKey = $view1->file_get_contents( 'encryption.key' ) 
			) {
			
				$plainLegacyKey = Crypt::legacyDecrypt( $encLegacyKey, $params['password'] );
				
				$session->setLegacyKey( $plainLegacyKey );
			
			}
			
			\OC_FileProxy::$enabled = false;
			
			$publicKey = Keymanager::getPublicKey( $view, $params['uid'] );
			
			\OC_FileProxy::$enabled = false;
			
			// Encrypt existing user files:
			// This serves to upgrade old versions of the encryption
			// app (see appinfo/spec.txt)
			if (
				$util->encryptAll( $publicKey,  '/' . $params['uid'] . '/' . 'files', $session->getLegacyKey(), $params['password'] )
			) {
				
				\OC_Log::write( 
					'Encryption library', 'Encryption of existing files belonging to "' . $params['uid'] . '" completed'
					, \OC_Log::INFO 
				);
			
			}
			
			// Register successful migration in DB
			$util->setMigrationStatus( 1 );
		
		}

		return true;

	}
	
	/**
	 * @brief Change a user's encryption passphrase
	 * @param array $params keys: uid, password
	 */
	public static function setPassphrase( $params ) {
		
		// Only attempt to change passphrase if server-side encryption
		// is in use (client-side encryption does not have access to 
		// the necessary keys)
		if ( Crypt::mode() == 'server' ) {

            $view = new \OC_FilesystemView( '/' );

			$session = new Session($view);
			
			// Get existing decrypted private key
			$privateKey = $session->getPrivateKey();
			
			// Encrypt private key with new user pwd as passphrase
			$encryptedPrivateKey = Crypt::symmetricEncryptFileContent( $privateKey, $params['password'] );
			
			// Save private key
			Keymanager::setPrivateKey( $encryptedPrivateKey );
			
			// NOTE: Session does not need to be updated as the 
			// private key has not changed, only the passphrase 
			// used to decrypt it has changed
			
		}
	
	}
	
	/**
	 * @brief update the encryption key of the file uploaded by the client
	 */
	public static function updateKeyfile( $params ) {
	
		if ( Crypt::mode() == 'client' ) {
			
			if ( isset( $params['properties']['key'] ) ) {
				
				$view = new \OC_FilesystemView( '/' );
				$userId = \OCP\User::getUser();
				
				Keymanager::setFileKey( $view, $params['path'], $userId, $params['properties']['key'] );
				
			} else {
				
				\OC_Log::write( 
					'Encryption library', "Client side encryption is enabled but the client doesn't provide a encryption key for the file!"
					, \OC_Log::ERROR 
				);
				
			}
			
		}
		
	}
	
	/**
	 * @brief 
	 */
	public static function preShared( $params ) {

		// NOTE: $params has keys:
		// [itemType] => file
		// itemSource -> int, filecache file ID
		// [parent] => 
		// [itemTarget] => /13
		// shareWith -> string, uid of user being shared to
		// fileTarget -> path of file being shared
		// uidOwner -> owner of the original file being shared
		// [shareType] => 0
		// [shareWith] => test1
		// [uidOwner] => admin
		// [permissions] => 17
		// [fileSource] => 13
		// [fileTarget] => /test8
		// [id] => 10
		// [token] =>
		// [run] => whether emitting script should continue to run
		// TODO: Should other kinds of item be encrypted too?
		
		if ( $params['itemType'] === 'file' || $params['itemType'] === 'folder' ) {

			$view = new \OC_FilesystemView( '/' );
			$session = new Session($view);
			$userId = \OCP\User::getUser();
			$util = new Util($view, $userId);
			$path = $util->fileIdToPath( $params['itemSource'] );

			//if parent is set, then this is a re-share action
			if( $params['parent'] ) {

				// get the parent from current share
				$parent = $util->getShareParent( $params['parent'] );

				// if parent is file the it is an 1:1 share
				if($parent['item_type'] === 'file') {

				// prefix path with Shared
				$path = '/Shared'.$parent['file_target'];

				} else {
				
					// NOTE: parent is folder but shared was a file!
					// we try to rebuild the missing path
					// some examples we face here
					// user1 share folder1 with user2 folder1 has 
					// the following structure 
					// /folder1/subfolder1/subsubfolder1/somefile.txt
					// user2 re-share subfolder2 with user3
					// user3 re-share somefile.txt user4
					// so our path should be 
					// /Shared/subfolder1/subsubfolder1/somefile.txt 
					// while user3 is sharing
					
					if ( $params['itemType'] === 'file' ) {
						// get target path
						$targetPath = $util->fileIdToPath( $params['fileSource'] );
						$targetPathSplit = array_reverse( explode( '/', $targetPath ) );

						// init values
						$path = '';
						$sharedPart = ltrim( $parent['file_target'], '/' );

						// rebuild path
						foreach ( $targetPathSplit as $pathPart ) {
						
							if ( $pathPart !== $sharedPart ) {
								
								$path = '/' . $pathPart . $path;
								
							} else {
							
								break;
								
							}
							
						}

						// prefix path with Shared
						$path = '/Shared'.$parent['file_target'].$path;

					} else {

						// prefix path with Shared
						$path = '/Shared'.$parent['file_target'].$params['fileTarget'];
					}
				}
			}

			$sharingEnabled = \OCP\Share::isEnabled();

			// if a folder was shared, get a list if all (sub-)folders
			if ( $params['itemType'] === 'folder' ) {
			
				$allFiles = $util->getAllFiles( $path );
				
			} else {
			
				$allFiles = array( $path );
				
			}
			
			// Set array for collecting paths which can't be shared
			$failed = array();

			foreach ( $allFiles as $path ) {
			
				$usersSharing = $util->getSharingUsersArray( $sharingEnabled, $path );

                // check if we share to a group
                if($params['shareType'] === \OCP\Share::SHARE_TYPE_GROUP) {
                    $usersSharing[] = reset(\OC_Group::usersInGroup($params['shareWith']));
                // check if we share with link
                } else if($params['shareType'] === \OCP\Share::SHARE_TYPE_LINK) {
                    $usersSharing[] = 'owncloud';
                } else {
                    // Because this is a pre_share hook, the user
                    // being shared to is not yet included; add them
                    $usersSharing[] = $params['shareWith'];
                }


				// Attempt to set shareKey
 				if ( ! $util->setSharedFileKeyfiles( $session, $usersSharing, $path ) ) {

					$failed[] = $path;
				}
			}
			
			// If some attempts to set keyfiles failed
			if ( ! empty( $failed ) ) {
				
				// Set flag var 'run' to notify emitting 
				// script that hook execution failed
				$params['run']->run = false;
                // TODO: Make sure files_sharing provides user
				// feedback on failed share
				
			}
		}
	}
	
	/**
	 * @brief 
	 */
	public static function postUnshare( $params ) {

		// NOTE: $params has keys:
		// [itemType] => file
		// [itemSource] => 13
		// [shareType] => 0
		// [shareWith] => test1
		// [itemParent] =>

		if ( $params['itemType'] === 'file' || $params['itemType'] === 'folder' ) {

			$view = new \OC_FilesystemView( '/' );
			$userId = \OCP\User::getUser();
			$util = new Util( $view, $userId);
			$path = $util->fileIdToPath( $params['itemSource'] );

			// check if this is a re-share
			if ( $params['itemParent'] ) {

				// get the parent from current share
				$parent = $util->getShareParent( $params['itemParent'] );

				// get target path
				$targetPath = $util->fileIdToPath( $params['itemSource'] );
				$targetPathSplit = array_reverse( explode( '/', $targetPath ) );

				// init values
				$path = '';
				$sharedPart = ltrim( $parent['file_target'], '/' );

				// rebuild path
				foreach ( $targetPathSplit as $pathPart ) {
				
					if ( $pathPart !== $sharedPart ) {
					
						$path = '/' . $pathPart . $path;
						
					} else {
					
						break;
						
					}
					
				}

				// prefix path with Shared
				$path = '/Shared' . $parent['file_target'] . $path;
			}

			// for group shares get a list of the group members
			if ( $params['shareType'] == \OCP\Share::SHARE_TYPE_GROUP ) {
			
				$userIds = \OC_Group::usersInGroup($params['shareWith']);
				
			} else {
			
				$userIds = array( $params['shareWith'] );
				
			}

			// if we unshare a folder we need a list of all (sub-)files
			if ( $params['itemType'] === 'folder' ) {
			
				$allFiles = $util->getAllFiles( $path );
				
			} else {
			
				$allFiles = array( $path );
			}

			foreach ( $allFiles as $path ) {

				// check if the user still has access to the file, otherwise delete share key
				$sharingUsers = $util->getSharingUsersArray( true, $path );

				// Unshare every user who no longer has access to the file
				$delUsers = array_diff( $userIds, $sharingUsers);
				
				if ( !Keymanager::delShareKey( $view, $delUsers, $path ) ) {
				
					$failed[] = $path;
				
				}

			}

			// If no attempts to set keyfiles failed
			if ( empty( $failed ) ) {
			
				return true;
				
			} else {
			
				return false;
				
			}
		}
	}
	
	/**
	 * @brief 
	 */
	public static function postUnshareAll( $params ) {

		// NOTE: It appears that this is never called for files, so 
		// we may not need to implement it
		
	}


    /**
     * @brief after a file is renamed, rename its keyfile and share-keys also fix the file size and fix also the sharing
     * @param array with oldpath and newpath
     *
     * This function is connected to the rename signal of OC_Filesystem and adjust the name and location
     * of the stored versions along the actual file
     */
    public static function postRename($params) {
        // Disable encryption proxy to prevent recursive calls
        $proxyStatus = \OC_FileProxy::$enabled;
        \OC_FileProxy::$enabled = false;

        $view = new \OC_FilesystemView('/');
        $session = new Session($view);
        $userId = \OCP\User::getUser();
        $util = new Util( $view, $userId );

        // Format paths to be relative to user files dir
        $oldKeyfilePath = $userId . '/' . 'files_encryption' . '/' . 'keyfiles' . '/' . $params['oldpath'];
        $newKeyfilePath = $userId . '/' . 'files_encryption' . '/' . 'keyfiles' . '/' . $params['newpath'];

        // add key ext if this is not an folder
        if (!$view->is_dir($oldKeyfilePath)) {
            $oldKeyfilePath .= '.key';
            $newKeyfilePath .= '.key';

            // handle share-keys
            $localKeyPath = $view->getLocalFile($userId.'/files_encryption/share-keys/'.$params['oldpath']);
            $matches = glob(preg_quote($localKeyPath).'*.shareKey');
            foreach ($matches as $src) {
                $dst = str_replace($params['oldpath'], $params['newpath'], $src);
                rename($src, $dst);
            }

        } else {
            // handle share-keys folders
            $oldShareKeyfilePath = $userId . '/' . 'files_encryption' . '/' . 'share-keys' . '/' . $params['oldpath'];
            $newShareKeyfilePath = $userId . '/' . 'files_encryption' . '/' . 'share-keys' . '/' . $params['newpath'];
            $view->rename($oldShareKeyfilePath, $newShareKeyfilePath);
        }

        // Rename keyfile so it isn't orphaned
        if($view->file_exists($oldKeyfilePath)) {
            $view->rename($oldKeyfilePath, $newKeyfilePath);
        }

        // build the path to the file
        $newPath = '/' . $userId . '/files' .$params['newpath'];
        $newPathRelative = $params['newpath'];

        if($util->fixFileSize($newPath)) {
            // get sharing app state
            $sharingEnabled = \OCP\Share::isEnabled();

            // get users
            $usersSharing = $util->getSharingUsersArray($sharingEnabled, $newPathRelative);

            // update sharing-keys
            $util->setSharedFileKeyfiles($session, $usersSharing, $newPathRelative);
        }

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