On Monday, April 8, 2024 at 6:12:23 PM UTC+2 [email protected] wrote:

There is a huge demand for protecting data that's shared with users  Any 
help in strong binding data to origin and blocking sharing would a big win.


I believe that is a different problem from the one we're trying to solve 
with this API. Would you happen to have more details about the issue you're 
referring to?
 


thx ..Tom (mobile)

On Mon, Apr 8, 2024, 1:20 AM Yoav Weiss (@Shopify) <[email protected]> 
wrote:

This is very interesting!

Do I understand correctly and the main reason this would be easier to 
deploy is because embedded iframes and popups won't need to deploy COEP in 
this model?


Yes. They also wouldn't need to deploy COOP, and so would be able to 
interact with cross-origin popups.
 


On Fri, Apr 5, 2024 at 12:14 PM Camille Lamy <[email protected]> wrote:

Yes the user agent keying is deterministic, and we're adding reporting to 
warn developers if they end up having two same origin documents that could 
normally have DOM access but can't due to Document-Isolation-Policy.


I'm not sure same-origin isolation won't end up being a desired feature 
on its own. I heard developers asking for stronger isolation primitives on 
more than one occasion. I'll talk to folks and think about it some more.
 

Our recommendation would be to adopt the header on all documents of an 
origin, which removes the concerns around script access. As a followup, we 
might resurrect the Origin-Policy work to help with this issue.


Origin-Policy would definitely help avoid mistakes here..
 


For COOP and COEP, you're correct to note that they are not available due 
to the platform limitations on Android WebView. Because of this, the 
crossOriginIsolated spec already has a notion of crossOriginIsolation being 
either logical (ie no API access) or effective (ie API access). We're 
building on this existing notion.

In terms of platform support, our goal is to first release on desktop, in 
order to finally end the ungated SAB reverse Origin Trial. Then we'll 
extend to Android (but not Android WebView). For Android, the situation is 
a bit different from full Site Isolation, because here the isolation and 
resulting increase memory consumption is driven by the website as opposed 
to the platform. We might not implement full functionality on low-end 
Android, but then none of the developers interested in the API want to have 
it run on low-end Android. Basically, this gives access to 
SharedArrayBuffers, which are mostly useful to cut calculation time in 
heavy web apps, that wouldn't run on devices with limited hardware.

Hope that helps!
Camille

On Thursday, April 4, 2024 at 9:45:04 PM UTC+2 Charlie Reis wrote:

I seem to recall that Android Chrome is also limited here, but maybe that 
has changed and my knowledge is outdated.


Correct, we don't usually create out-of-process iframes on Android Chrome 
if the device has less than 2G of RAM.  Otherwise we allow it (e.g., for 
partial 
Site Isolation 
<https://chromium.googlesource.com/chromium/src/+/main/docs/process_model_and_site_isolation.md#Partial-Site-Isolation>).
  
I'm not sure if COOP+COEP has any restrictions on low-end Android devices, 
since that mode requires multiple processes but not out-of-process 
iframes.  For Document-Isolation-Policy, I believe there's some notes about 
low-end Android devices in the explainer, maybe suggesting that it's less 
needed on such devices?  I'll let Camille clarify.

Charlie 

On Thu, Apr 4, 2024 at 12:27 PM Vladimir Levin <[email protected]> wrote:



On Thu, Apr 4, 2024 at 12:11 PM Charlie Reis <[email protected]> wrote:

My understanding is that at least this behavior is deterministic, right? 
That is, either the same-origin frames will be able to script each other or 
they won't and this will happen consistently (based on the agent cluster 
key).


Yes, I think it would be deterministic based on the headers, so hopefully 
education via error messages would help.

An observation I had is that it seems that the Document-Isolation-Policy is 
still at the mercy of the platform having the resources to process-isolate 
frames.


Camille can probably confirm the details, but I believe that's right.  
COOP+COEP depends on the platform being able to open a new window in a 
different process, which I think all platforms but Android WebView can 
support at this point (?).  Document-Isolation-Policy would depend on 
out-of-process iframes, which wouldn't work on Android WebView or iOS, at 
least for the time being.  On platforms that do support out-of-process 
iframes, it would make crossOriginIsolated modes much easier to adopt, 
though.


I seem to recall that Android Chrome is also limited here, but maybe that 
has changed and my knowledge is outdated.
 


Also I'm not sure if it would be possible for 3p iframes to starve platform 
of such resources so that the top level frame would no longer be able to 
create 1p frames that have access to COI-gated APIs


IIUC, I think each origin is limited in the number of processes it could 
create in a given page (basically one with SAB access and one without), 
which helps.


Ah that makes sense. There may still be some possibility with just spamming 
3p iframes but that likely exists today anyway

Thanks!
Vlad
 


Charlie 

On Thu, Apr 4, 2024 at 8:05 AM Vladimir Levin <[email protected]> wrote:

This does sound a bit unfortunate. My understanding is that at least this 
behavior is deterministic, right? That is, either the same-origin frames 
will be able to script each other or they won't and this will happen 
consistently (based on the agent cluster key).

An observation I had is that it seems that the Document-Isolation-Policy is 
still at the mercy of the platform having the resources to process-isolate 
frames. It wasn't clear to me from the explainer whether this is already a 
limitation with the COOP and COEP approaches, however unwieldy those may 
be. This basically means that one of the listed use-case of authors 
maintaining two copies of their widgets -- one with SharedArrayBuffers, one 
without -- doesn't seem to be addressed. Also I'm not sure if it would be 
possible for 3p iframes to starve platform of such resources so that the 
top level frame would no longer be able to create 1p frames that have 
access to COI-gated APIs

(I also don't know what is the right forum in which to raise these issues)

Thanks,
Vlad

On Wed, Apr 3, 2024 at 1:54 PM Charlie Reis <[email protected]> wrote:

Thanks for sharing this.  I do think it's worth calling attention to this 
paragraph 
<https://github.com/explainers-by-googlers/document-isolation-policy?tab=readme-ov-file#browsing-context-group-switch-instead-of-agent-cluster-keying>
 
of the explainer, for one thing to consider about the proposal:

The Document-Isolation-Policy proposal relies on agent cluster keying to 
achieve isolation, instead of browsing context group switches. This means 
that it introduces a situation where two same-origin documents might find 
themselves in different agent clusters and be unable to have DOM access to 
each other. This is unprecedented in the HTML spec.


In other words, two same-origin frames within the same page (or anywhere in 
the same browsing context group) can end up in different processes, unable 
to script each other.  It could be that this is considered fine and might 
be outweighed by the benefits of the proposal, though it does have some 
implications for web developers and for the browser's implementation:

   - Web developers might be confused when some attempts to script a 
   same-origin frame fail, since this has always been possible within a given 
   browsing context group.  Maybe this can be mitigated with a different type 
   of error message in the DevTools console?
   - In Chromium's implementation, both the browser process and renderer 
   process make assumptions that same-origin frames within the same browsing 
   context group (also known as content::BrowsingInstance) must be in the same 
   process so that they can script each other.  Dividing that up based on 
   Document-Isolation-Policy seems like it should be possible, though it would 
   add some complexity and might require some auditing of process model 
   
<https://chromium.googlesource.com/chromium/src/+/main/docs/process_model_and_site_isolation.md>
 
   code.

Maybe this is a manageable risk?

Thanks,
Charlie


On Wed, Apr 3, 2024 at 5:41 AM Camille Lamy <[email protected]> wrote:

Contact [email protected]

Explainerhttps://github.com/explainers-by-googlers/document-isolation-policy

SpecificationNone

Summary

Document-Isolation-Policy allows a document to enable crossOriginIsolation 
for itself, without having to deploy COOP or COEP, and regardless of the 
crossOriginIsolation status of the page. The policy is backed by process 
isolation. Additionally, the document non-CORS cross-origin subresources 
will either be loaded without credentials or will need to have a CORP 
header.


Blink componentBlink>SecurityFeature 
<https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3ESecurityFeature>

Motivation

Developers want to build applications that are fast using 
SharedArrayBuffers (SAB), which can improve computation time by ~40%. But 
SharedArrayBuffers allow to create high-precision timers that can be 
exploited in a Spectre attack, allowing to leak cross-origin user data. To 
mitigate the risk, SharedArrayBuffers are gated behind crossOriginIsolation 
(COI). CrossOriginIsolation requires to deploy both 
Cross-Origin-Opener-Policy (COOP) and Cross-Origin-Embedder-Policy (COEP). 
Both have proven hard to deploy, COOP because it prevents communication 
with cross-origin popups, and COEP because it imposes restrictions on 
third-party embeds. Finally, the whole COOP + COEP model is focused on 
providing access to SharedArrayBuffers to the top-level frame. Cross-origin 
embeds can only use SABs if their embedder deploys crossOriginIsolation and 
delegates the permission to use COI-gated APIs, making the availability of 
SABs in third-party iframes very unreliable. Document-Isolation-Policy, is 
proposing to solve these deployment concerns by relying on the browser 
Out-of-Process-Iframe capability. It will provide a way to securely build 
fast applications using SharedArrayBuffers while maintaining communication 
with cross-origin popups and not requiring extra work to embed cross-origin 
iframes. Finally, it will be available for embedded widgets.


Initial public proposalhttps://github.com/WICG/proposals/issues/145

TAG reviewNone

TAG review statusPending

Risks


Interoperability and Compatibility

None


*Gecko*: No signal

*WebKit*: No signal

*Web developers*: No signals

*Other signals*:

WebView application risks

Does this intent deprecate or change behavior of existing APIs, such that 
it has potentially high risk for Android WebView-based applications?

None


Debuggability

None


Is this feature fully tested by web-platform-tests 
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>
?No

Flag name on chrome://flagsNone

Finch feature nameNone

Non-finch justificationNone

Requires code in //chrome?False

Estimated milestones

No milestones specified


Link to entry on the Chrome Platform Statushttps://chromestatus.com/
feature/5141940204208128?gate=5097535879512064

This intent message was generated by Chrome Platform Status 
<https://chromestatus.com/>.

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