Only allow file upload in the Documents section of your drive

www/common/drive-ui.js

@@ -1775,6 +1775,13 @@ define([
                 target: e.target,
                 path: findDropPath(e.target)
             };
+
+            // Make sure we can only upload files in the Documents tree
+            var p = ev.path;
+            if (!Array.isArray(p) || !p.length || p[0] !== ROOT) {
+                return void UI.warn(Messages.error); // XXX new translation key? "~Can"t upload a file here"
+            }
+
             APP.FM.onFileDrop(file, ev);
         };
         var onDrop = function (ev) {