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. 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.
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 has changed and my knowledge is outdated.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 <vmp...@chromium.org> > wrote: > >> >> >> On Thu, Apr 4, 2024 at 12:11 PM Charlie Reis <cr...@chromium.org> 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 <vmp...@chromium.org> >>> 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 <cr...@chromium.org> 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 <cl...@chromium.org> >>>>> wrote: >>>>> >>>>>> Contact emailscl...@google.com >>>>>> >>>>>> Explainer >>>>>> https://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 Status >>>>>> https://chromestatus.com/feature/5141940204208128?gate=5097535879512064 >>>>>> >>>>>> This intent message was generated by Chrome Platform Status >>>>>> <https://chromestatus.com/>. >>>>>> >>>>>> -- >>>>>> You received this message because you are subscribed to the Google >>>>>> Groups "blink-dev" group. >>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>> send an email to blink-dev+unsubscr...@chromium.org. >>>>>> To view this discussion on the web visit >>>>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAMKsNvp7Xcgz%3DcMXJ7%2B%2BBgwhO2wOKEkaMiDk_wUY1nprvPG4HQ%40mail.gmail.com >>>>>> >>>>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAMKsNvp7Xcgz%3DcMXJ7%2B%2BBgwhO2wOKEkaMiDk_wUY1nprvPG4HQ%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>>>> . >>>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "blink-dev" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to blink-dev+unsubscr...@chromium.org. >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAH%2B8MBZfpRCRsQMqvjy8NPmo9_v8WQcdu%3Ds06%2BVWb6a17dQ-jw%40mail.gmail.com >>>>> >>>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAH%2B8MBZfpRCRsQMqvjy8NPmo9_v8WQcdu%3Ds06%2BVWb6a17dQ-jw%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>>> . >>>>> >>>> -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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