Re: [webkit-dev] Request for position on import maps

[Thomas Steiner via webkit-dev]

Hi all,

I realized that there wasn’t a WebKit bug asking for import maps support

Re: [webkit-dev] Request for position on import maps

[Domenic Denicola]

Thanks for your response Ryosuke!

From: Ryosuke Niwa  

> How does this feature supposed to work with CSP subresource integrity?
>As far as I've read various specs and the proposal, it's not currently 
>possible to specify any integrity checks on modules loaded via import this. 
>This is a pretty serious downside because it would mean that any remote server 
>ever referenced by an import map becomes a security liability for a given 
>website. It's a lot worse compared to normal scripts > because of the 
>action-at-a-distance of import maps. There is no indication that a given 
>module import could involve access to cross-origin servers isn't obvious from 
>where the import statement appears.

Correct, this proposal does not change the status quo regarding models and CSP 
integrity integration. I can understand how import maps might increase the 
priority of improving CSP in that way for WebKit, and I imagine the webappsec 
group would welcome any collaboration on solving that. 

There are even proposals from community members to piggyback on the import 
map's 

Re: [webkit-dev] Request for position on import maps

[Ryosuke Niwa]

On Tue, Oct 27, 2020 at 2:23 PM Domenic Denicola  wrote:
>
> For the last couple of years myself some other Chrome folks have been working 
> on the import maps proposal. This allows controlling the behavior of 
> JavaScript import statements and import() expressions, in particular by 
> allowing the page to customize the translation of the module specifiers used 
> there into URLs. Developer reception of the feature has been very positive, 
> with continual prompting for when it'll be widely available in more browsers, 
> and a plethora of community-created tools and polyfills.
>
> Chrome is working toward shipping this in an imminent release, and we'd love 
> any thoughts or contributions from the WebKit community.

How does this feature supposed to work with CSP subresource integrity?
As far as I've read various specs and the proposal, it's not currently
possible to specify any integrity checks on modules loaded via import
this. This is a pretty serious downside because it would mean that any
remote server ever referenced by an import map becomes a security
liability for a given website. It's a lot worse compared to normal
scripts because of the action-at-a-distance of import maps. There is
no indication that a given module import could involve access to
cross-origin servers isn't obvious from where the import statement
appears.

- R. Niwa
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