Mark drags starting in web content as tainted to avoid file path forgery

content/public/common/drop_data.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // A struct for managing data being dropped on a WebContents.  This represents
 // a union of all the types of data that can be dropped in a platform neutral
 // way.
 
 #ifndef CONTENT_PUBLIC_COMMON_DROP_DATA_H_
 #define CONTENT_PUBLIC_COMMON_DROP_DATA_H_
@@ skipping 17 matching lines @@
 
     // The path of the file.
     base::string16 path;
     // The display name of the file. This field is optional.
     base::string16 display_name;
   };
 
   DropData();
   ~DropData();
 
+  // Whether this drag originated from a renderer.
+  bool did_originate_from_renderer;
+
   // User is dragging a link into the webview.
   GURL url;
   base::string16 url_title;  // The title associated with |url|.
 
   // User is dragging a link out-of the webview.
   base::string16 download_metadata;
 
   // Referrer policy to use when dragging a link out of the webview results in
   // a download.
   blink::WebReferrerPolicy referrer_policy;
 
-  // User is dropping one or more files on the webview.
+  // User is dropping one or more files on the webview. This field is only
+  // populated if the drag is not renderer tainted, as this allows File access
+  // from web content.
   std::vector<FileInfo> filenames;
 
   // Isolated filesystem ID for the files being dragged on the webview.
   base::string16 filesystem_id;
 
   // User is dragging plain text into the webview.
   base::NullableString16 text;
 
   // User is dragging text/html into the webview (e.g., out of Firefox).
   // |html_base_url| is the URL that the html fragment is taken from (used to
   // resolve relative links).  It's ok for |html_base_url| to be empty.
   base::NullableString16 html;
   GURL html_base_url;
 
   // User is dragging data from the webview (e.g., an image).
   base::string16 file_description_filename;
   std::string file_contents;
 
   std::map<base::string16, base::string16> custom_data;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_COMMON_DROP_DATA_H_