MDL-36977 Be more picky when it comes to migrating files in moodle1 backups

backup/converter/moodle1/lib.php

@@ -642,7 +642,9 @@ class moodle1_converter extends base_converter {
         }
         foreach ($matches[2] as $match) {
             $file = str_replace(array('$@FILEPHP@$', '$@SLASH@$', '$@FORCEDOWNLOAD@$'), array('', '/', ''), $match);
-            $files[] = rawurldecode($file);
+            if ($file === clean_param($file, PARAM_PATH)) {
+                $files[] = rawurldecode($file);
+            }
         }
 
         return array_unique($files);
@@ -1210,6 +1212,10 @@ class moodle1_file_manager implements loggable {
 
         $sourcefullpath = $this->basepath.'/'.$sourcepath;
 
+        if ($sourcefullpath !== clean_param($sourcefullpath, PARAM_PATH)) {
+            throw new moodle1_convert_exception('file_invalid_path', $sourcefullpath);
+        }
+
         if (!is_readable($sourcefullpath)) {
             throw new moodle1_convert_exception('file_not_readable', $sourcefullpath);
         }