1915653 - If custom data is on the clipboard, Content Analysis will run every time a clipboard event is fired

Status: RESOLVED DUPLICATE of bug 1915351

(Firefox :: Data Loss Prevention, enhancement)

Description

[Greg Stoll :gstoll]

When a clipboard event happens, DataTransfer::CacheExternalData() sets up the types of data that are in the clipboard without getting the actual data. However, for custom data, DataTransfer::FillInExternalCustomTypes() has to get the custom data to parse out what types are in there, and this triggers content analysis even if the website doesn't try to get the custom data.

Instead, we could add a way to get the clipboard contents bypassing content analysis, and adding a flag to DataTransferItem that indicates content analysis needs to be run before handing out the data to JS.

Comment 1

[Greg Stoll :gstoll]

Attachment: Bug 1915653 - don't run Content Analysis on custom data types in clipboard when they're created r=#dlp-reviewers!

Because the clipboard code has to read the data stored in kCustomTypesMime in order to
parse their real types/data, this was causing content analysis to be run on that data
(after bug 1913760; before that we weren't running content analysis on this data at all)
even if the JS never actually got that data. This change bypasses content analysis when
doing the parsing and only runs content analysis when something external calls to get the data.

Comment 2

[Greg Stoll :gstoll]

This is an extension of the problem in bug 1915351, and the fix to that bug will fix this.