1 files changed, 206 insertions, 0 deletions
diff --git a/lib/private/Repair/RemoveLinkShares.php b/lib/private/Repair/RemoveLinkShares.php
new file mode 100644
index 00000000000..a07ebdb72c3
--- /dev/null
+++ b/lib/private/Repair/RemoveLinkShares.php
@@ -0,0 +1,206 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2019 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OC\Repair;
+
+use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\DB\IResult;
+use OCP\DB\QueryBuilder\IQueryBuilder;
+use OCP\IConfig;
+use OCP\IDBConnection;
+use OCP\IGroupManager;
+use OCP\Migration\IOutput;
+use OCP\Migration\IRepairStep;
+use OCP\Notification\IManager;
+
+class RemoveLinkShares implements IRepairStep {
+	/** @var string[] */
+	private $userToNotify = [];
+
+	public function __construct(
+		private IDBConnection $connection,
+		private IConfig $config,
+		private IGroupManager $groupManager,
+		private IManager $notificationManager,
+		private ITimeFactory $timeFactory,
+	) {
+	}
+
+	public function getName(): string {
+		return 'Remove potentially over exposing share links';
+	}
+
+	private function shouldRun(): bool {
+		$versionFromBeforeUpdate = $this->config->getSystemValueString('version', '0.0.0');
+
+		if (version_compare($versionFromBeforeUpdate, '14.0.11', '<')) {
+			return true;
+		}
+		if (version_compare($versionFromBeforeUpdate, '15.0.8', '<')) {
+			return true;
+		}
+		if (version_compare($versionFromBeforeUpdate, '16.0.0', '<=')) {
+			return true;
+		}
+
+		return false;
+	}
+
+	/**
+	 * Delete the share
+	 *
+	 * @param int $id
+	 */
+	private function deleteShare(int $id): void {
+		$qb = $this->connection->getQueryBuilder();
+		$qb->delete('share')
+			->where($qb->expr()->eq('id', $qb->createNamedParameter($id)));
+		$qb->executeStatement();
+	}
+
+	/**
+	 * Get the total of affected shares
+	 *
+	 * @return int
+	 */
+	private function getTotal(): int {
+		$subSubQuery = $this->connection->getQueryBuilder();
+		$subSubQuery->select('*')
+			->from('share')
+			->where($subSubQuery->expr()->isNotNull('parent'))
+			->andWhere($subSubQuery->expr()->eq('share_type', $subSubQuery->expr()->literal(3, IQueryBuilder::PARAM_INT)));
+
+		$subQuery = $this->connection->getQueryBuilder();
+		$subQuery->select('s1.id')
+			->from($subQuery->createFunction('(' . $subSubQuery->getSQL() . ')'), 's1')
+			->join(
+				's1', 'share', 's2',
+				$subQuery->expr()->eq('s1.parent', 's2.id')
+			)
+			->where($subQuery->expr()->orX(
+				$subQuery->expr()->eq('s2.share_type', $subQuery->expr()->literal(1, IQueryBuilder::PARAM_INT)),
+				$subQuery->expr()->eq('s2.share_type', $subQuery->expr()->literal(2, IQueryBuilder::PARAM_INT))
+			))
+			->andWhere($subQuery->expr()->eq('s1.item_source', 's2.item_source'));
+
+		$query = $this->connection->getQueryBuilder();
+		$query->select($query->func()->count('*', 'total'))
+			->from('share')
+			->where($query->expr()->in('id', $query->createFunction($subQuery->getSQL())));
+
+		$result = $query->executeQuery();
+		$data = $result->fetch();
+		$result->closeCursor();
+
+		return (int)$data['total'];
+	}
+
+	/**
+	 * Get the cursor to fetch all the shares
+	 */
+	private function getShares(): IResult {
+		$subQuery = $this->connection->getQueryBuilder();
+		$subQuery->select('*')
+			->from('share')
+			->where($subQuery->expr()->isNotNull('parent'))
+			->andWhere($subQuery->expr()->eq('share_type', $subQuery->expr()->literal(3, IQueryBuilder::PARAM_INT)));
+
+		$query = $this->connection->getQueryBuilder();
+		$query->select('s1.id', 's1.uid_owner', 's1.uid_initiator')
+			->from($query->createFunction('(' . $subQuery->getSQL() . ')'), 's1')
+			->join(
+				's1', 'share', 's2',
+				$query->expr()->eq('s1.parent', 's2.id')
+			)
+			->where($query->expr()->orX(
+				$query->expr()->eq('s2.share_type', $query->expr()->literal(1, IQueryBuilder::PARAM_INT)),
+				$query->expr()->eq('s2.share_type', $query->expr()->literal(2, IQueryBuilder::PARAM_INT))
+			))
+			->andWhere($query->expr()->eq('s1.item_source', 's2.item_source'));
+		/** @var IResult $result */
+		$result = $query->executeQuery();
+		return $result;
+	}
+
+	/**
+	 * Process a single share
+	 *
+	 * @param array $data
+	 */
+	private function processShare(array $data): void {
+		$id = $data['id'];
+
+		$this->addToNotify($data['uid_owner']);
+		$this->addToNotify($data['uid_initiator']);
+
+		$this->deleteShare((int)$id);
+	}
+
+	/**
+	 * Update list of users to notify
+	 *
+	 * @param string $uid
+	 */
+	private function addToNotify(string $uid): void {
+		if (!isset($this->userToNotify[$uid])) {
+			$this->userToNotify[$uid] = true;
+		}
+	}
+
+	/**
+	 * Send all notifications
+	 */
+	private function sendNotification(): void {
+		$time = $this->timeFactory->getDateTime();
+
+		$notification = $this->notificationManager->createNotification();
+		$notification->setApp('core')
+			->setDateTime($time)
+			->setObject('repair', 'exposing_links')
+			->setSubject('repair_exposing_links');
+
+		$users = array_keys($this->userToNotify);
+		foreach ($users as $user) {
+			$notification->setUser((string)$user);
+			$this->notificationManager->notify($notification);
+		}
+	}
+
+	private function repair(IOutput $output, int $total): void {
+		$output->startProgress($total);
+
+		$shareResult = $this->getShares();
+		while ($data = $shareResult->fetch()) {
+			$this->processShare($data);
+			$output->advance();
+		}
+		$output->finishProgress();
+		$shareResult->closeCursor();
+
+		// Notify all admins
+		$adminGroup = $this->groupManager->get('admin');
+		$adminUsers = $adminGroup->getUsers();
+		foreach ($adminUsers as $user) {
+			$this->addToNotify($user->getUID());
+		}
+
+		$output->info('Sending notifications to admins and affected users');
+		$this->sendNotification();
+	}
+
+	public function run(IOutput $output): void {
+		if ($this->shouldRun() === false || ($total = $this->getTotal()) === 0) {
+			$output->info('No need to remove link shares.');
+			return;
+		}
+
+		$output->info('Removing potentially over exposing link shares');
+		$this->repair($output, $total);
+		$output->info('Removed potentially over exposing link shares');
+	}
+}