Disable link shares of disabled users

Fixes #10869

Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>

Author: rullzer

apps/files_sharing/lib/Controller/ShareController.php

@@ -266,6 +266,18 @@ protected function emitAccessShareHook($share, $errorCode = 200, $errorMessage =
 	 * @return bool
 	 */
 	private function validateShare(\OCP\Share\IShare $share) {
+		// If the owner is disabled no access to the linke is granted
+		$owner = $this->userManager->get($share->getShareOwner());
+		if ($owner === null || !$owner->isEnabled()) {
+			return false;
+		}
+
+		// If the initiator of the share is disabled no access is granted
+		$initiator = $this->userManager->get($share->getSharedBy());
+		if ($initiator === null || !$initiator->isEnabled()) {
+			return false;
+		}
+
 		return $share->getNode()->isReadable() && $share->getNode()->isShareable();
 	}