add migration for encryption keys in wrong location

Signed-off-by: Robin Appelman <robin@icewind.nl>

apps/encryption/appinfo/info.xml

@@ -46,6 +46,7 @@
 		<command>OCA\Encryption\Command\RecoverUser</command>
 		<command>OCA\Encryption\Command\ScanLegacyFormat</command>
 		<command>OCA\Encryption\Command\FixEncryptedVersion</command>
+		<command>OCA\Encryption\Command\FixKeyLocation</command>
 	</commands>
 
 	<settings>

apps/encryption/composer/composer/autoload_classmap.php

@@ -11,6 +11,7 @@ return array(
     'OCA\\Encryption\\Command\\DisableMasterKey' => $baseDir . '/../lib/Command/DisableMasterKey.php',
     'OCA\\Encryption\\Command\\EnableMasterKey' => $baseDir . '/../lib/Command/EnableMasterKey.php',
     'OCA\\Encryption\\Command\\FixEncryptedVersion' => $baseDir . '/../lib/Command/FixEncryptedVersion.php',
+    'OCA\\Encryption\\Command\\FixKeyLocation' => $baseDir . '/../lib/Command/FixKeyLocation.php',
     'OCA\\Encryption\\Command\\RecoverUser' => $baseDir . '/../lib/Command/RecoverUser.php',
     'OCA\\Encryption\\Command\\ScanLegacyFormat' => $baseDir . '/../lib/Command/ScanLegacyFormat.php',
     'OCA\\Encryption\\Controller\\RecoveryController' => $baseDir . '/../lib/Controller/RecoveryController.php',

apps/encryption/composer/composer/autoload_static.php

@@ -26,6 +26,7 @@ class ComposerStaticInitEncryption
         'OCA\\Encryption\\Command\\DisableMasterKey' => __DIR__ . '/..' . '/../lib/Command/DisableMasterKey.php',
         'OCA\\Encryption\\Command\\EnableMasterKey' => __DIR__ . '/..' . '/../lib/Command/EnableMasterKey.php',
         'OCA\\Encryption\\Command\\FixEncryptedVersion' => __DIR__ . '/..' . '/../lib/Command/FixEncryptedVersion.php',
+        'OCA\\Encryption\\Command\\FixKeyLocation' => __DIR__ . '/..' . '/../lib/Command/FixKeyLocation.php',
         'OCA\\Encryption\\Command\\RecoverUser' => __DIR__ . '/..' . '/../lib/Command/RecoverUser.php',
         'OCA\\Encryption\\Command\\ScanLegacyFormat' => __DIR__ . '/..' . '/../lib/Command/ScanLegacyFormat.php',
         'OCA\\Encryption\\Controller\\RecoveryController' => __DIR__ . '/..' . '/../lib/Controller/RecoveryController.php',

apps/encryption/lib/Command/FixKeyLocation.php

@@ -0,0 +1,186 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * @copyright Copyright (c) 2022 Robin Appelman <robin@icewind.nl>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * 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
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\Encryption\Command;
+
+use OC\Encryption\Util;
+use OC\Files\View;
+use OCP\Files\Config\ICachedMountInfo;
+use OCP\Files\Config\IUserMountCache;
+use OCP\Files\Folder;
+use OCP\Files\File;
+use OCP\Files\IRootFolder;
+use OCP\Files\Node;
+use OCP\IUser;
+use OCP\IUserManager;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+
+class FixKeyLocation extends Command {
+	private IUserManager $userManager;
+	private IUserMountCache $userMountCache;
+	private Util $encryptionUtil;
+	private IRootFolder $rootFolder;
+	private string $keyRootDirectory;
+	private View $rootView;
+
+	public function __construct(IUserManager $userManager, IUserMountCache $userMountCache, Util $encryptionUtil, IRootFolder $rootFolder) {
+		$this->userManager = $userManager;
+		$this->userMountCache = $userMountCache;
+		$this->encryptionUtil = $encryptionUtil;
+		$this->rootFolder = $rootFolder;
+		$this->keyRootDirectory = rtrim($this->encryptionUtil->getKeyStorageRoot(), '/');
+		$this->rootView = new View();
+
+		parent::__construct();
+	}
+
+
+	protected function configure(): void {
+		parent::configure();
+
+		$this
+			->setName('encryption:fix-key-location')
+			->setDescription('Fix the location of encryption keys for external storage')
+			->addOption('dry-run', null, InputOption::VALUE_NONE, "Only list files that require key migration, don't try to perform any migration")
+			->addArgument('user', InputArgument::REQUIRED, "User id to fix the key locations for");
+	}
+
+	protected function execute(InputInterface $input, OutputInterface $output): int {
+		$dryRun = $input->getOption('dry-run');
+		$userId = $input->getArgument('user');
+		$user = $this->userManager->get($userId);
+		if (!$user) {
+			$output->writeln("<error>User $userId not found</error>");
+			return 1;
+		}
+
+		\OC_Util::setupFS($user->getUID());
+
+		$mounts = $this->getSystemMountsForUser($user);
+		foreach ($mounts as $mount) {
+			$mountRootFolder = $this->rootFolder->get($mount->getMountPoint());
+			if (!$mountRootFolder instanceof Folder) {
+				$output->writeln("<error>System wide mount point is not a directory, skipping: " . $mount->getMountPoint() . "</error>");
+				continue;
+			}
+
+			$files = $this->getAllFiles($mountRootFolder);
+			foreach ($files as $file) {
+				if ($this->isKeyStoredForUser($user, $file)) {
+					if ($dryRun) {
+						$output->writeln("<info>" . $file->getPath() . "</info> needs migration");
+					} else {
+						$output->write("Migrating key for <info>" . $file->getPath() . "</info> ");
+						if ($this->copyKeyAndValidate($user, $file)) {
+							$output->writeln("<info>✓</info>");
+						} else {
+							$output->writeln("<fg=red>❌</>");
+							$output->writeln("  Failed to validate key for <error>" . $file->getPath() . "</error>, key will not be migrated");
+						}
+					}
+				}
+			}
+		}
+
+		return 0;
+	}
+
+	/**
+	 * @param IUser $user
+	 * @return ICachedMountInfo[]
+	 */
+	private function getSystemMountsForUser(IUser $user): array {
+		return array_filter($this->userMountCache->getMountsForUser($user), function(ICachedMountInfo $mount) use ($user) {
+			$mountPoint = substr($mount->getMountPoint(), strlen($user->getUID() . '/'));
+			return $this->encryptionUtil->isSystemWideMountPoint($mountPoint, $user->getUID());
+		});
+	}
+
+	/**
+	 * @param Folder $folder
+	 * @return \Generator<File>
+	 */
+	private function getAllFiles(Folder $folder) {
+		foreach ($folder->getDirectoryListing() as $child) {
+			if ($child instanceof Folder) {
+				yield from $this->getAllFiles($child);
+			} else {
+				yield $child;
+			}
+		}
+	}
+
+	/**
+	 * Check if the key for a file is stored in the user's keystore and not the system one
+	 *
+	 * @param IUser $user
+	 * @param Node $node
+	 * @return bool
+	 */
+	private function isKeyStoredForUser(IUser $user, Node $node): bool {
+		$path = trim(substr($node->getPath(), strlen($user->getUID()) + 1), '/');
+		$systemKeyPath = $this->keyRootDirectory . '/files_encryption/keys/' . $path . '/';
+		$userKeyPath = $this->keyRootDirectory . '/' . $user->getUID() . '/files_encryption/keys/' . $path . '/';
+
+		// this uses View instead of the RootFolder because the keys might not be in the cache
+		$systemKeyExists = $this->rootView->file_exists($systemKeyPath);
+		$userKeyExists = $this->rootView->file_exists($userKeyPath);
+		return $userKeyExists && !$systemKeyExists;
+	}
+
+	/**
+	 * Check that the user key stored for a file can decrypt the file
+	 *
+	 * @param IUser $user
+	 * @param File $node
+	 * @return bool
+	 */
+	private function copyKeyAndValidate(IUser $user, File $node): bool {
+		$path = trim(substr($node->getPath(), strlen($user->getUID()) + 1), '/');
+		$systemKeyPath = $this->keyRootDirectory . '/files_encryption/keys/' . $path . '/';
+		$userKeyPath = $this->keyRootDirectory . '/' . $user->getUID() . '/files_encryption/keys/' . $path . '/';
+
+		$this->rootView->copy($userKeyPath, $systemKeyPath);
+		try {
+			// check that the copied key is valid
+			$fh = $node->fopen('r');
+			// read a single chunk
+			$data = fread($fh, 8192);
+			if ($data === false) {
+				throw new \Exception("Read failed");
+			}
+
+			// cleanup wrong key location
+			$this->rootView->rmdir($userKeyPath);
+			return true;
+		} catch (\Exception $e) {
+			// remove the copied key if we know it's invalid
+			$this->rootView->rmdir($systemKeyPath);
+			return false;
+		}
+	}
+}