LGTM1 to ship the ID assertion endpoint CORS requirements. On Wed, Mar 13, 2024 at 3:11 PM Nicolás Peña <n...@chromium.org> wrote:
> > On Wednesday, March 13, 2024 at 7:37:29 AM UTC-4 Yoav Weiss wrote: > > On Tuesday, March 12, 2024 at 3:11:24 PM UTC-4 Nicolás Peña wrote: > > Regarding risk: we are going to implement this and test the IDPs we know > are currently using FedCM, but we do not anticipate them to break since > they are currently already relying on using third-party cookies in iframes. > We also plan to have developer outreach/blogpost for this change so > developers currently testing out FedCM are not caught by surprise. > > Regarding vendor alignment: we have been working with Firefox and Apple to > align on the correct behavior of the FedCM fetches: see > https://github.com/fedidcg/FedCM/issues/320 and > https://github.com/fedidcg/FedCM/issues/428. This I2S is a result of a > lot of discussions, and the small addition was a result of a very recent > discussion occurring on our FedCM CORS breakout session > <https://www.w3.org/2024/03/breakouts-day-2024/#b-15220813-651d-4795-98ae-a17434c1e50f> > . > > Regarding spec, during our breakout Anne also mentioned that the small > addition is not possible to specify properly, as it depends on the ongoing > cookie layering work. I will add a note > <https://github.com/fedidcg/FedCM/pull/550> on the spec in that fetch so > IDPs know which cookies should be sent. > > Anyways, I understand it is a bit late to add something to this I2S so if > you prefer that we send a separate I2S/PSA for the SameSite change, we can > do that instead. > > > Is the accounts endpoint the same endpoint to which this intent applies? > Or is it different from the ID assertion endpoint? > If it's different, a separate I2S would be best. If it's the same, then I > think we can probably fold it into this intent. > > > This change is to the ID assertion endpoint, which is different from the > accounts endpoint. Then based on your comment, we will keep those two in > separate intents. Consider the small addition I suggested above removed. > > > > > > > On Tuesday, March 12, 2024 at 1:34:56 PM UTC-4 Mike Taylor wrote: > > On 3/12/24 11:33 AM, Nicolás Peña Moreno wrote: > > Thanks for the suggestion, Yoav! It seems something fetch experts have > some concerns about, so we do not plan to proceed with that suggestion at > the moment. > > Thanks for considering! Anne makes a good point that active defense here > (by filtering requests based on destination) would work better against > timing attacks than passive defense (where the responses are blocked by the > browser). Please make sure that IDPs are aware of the destination filtering > requirement, by having it emphasized in developer facing documentation. > > > Yes, we will work with devrel to continue ensuring IDP best practices are > easily discoverable. > > > > I'd like to append a small addition to this I2S (mainly to avoid having an > additional PSA since it is very related to this one): we would also like > approval to only send Same-Site=None cookies in the accounts endpoint, > instead of all cookies (so not Same-Site=Lax or Same-Site=Strict). This is > also a breaking change but we do not anticipate IDPs to break, and also > plan to work with them to ensure that they are aware of this change and are > not caught by surprise. > > To my non-FedCM expert brain, this doesn't feel like a small addition > (happy to be wrong!), beyond not understanding the scale of the risk, the > normal process questions come to mind i.e., is it specced, do we have > tests, what do other vendors think about it? > > > On Monday, March 11, 2024 at 6:39:14 AM UTC-4 Yoav Weiss wrote: > > <owner hat off> > I left a comment > <https://github.com/fedidcg/FedCM/issues/428#issuecomment-1980469172> around > potentially adding a CORS mode that would help IDP servers statically > protect themselves from destination-change attacks. I don't *think* it's a > blocker, but it's worth considering something along those lines to increase > the solution's robustness to configuration errors, and ensure it fails > closed. (and ask IDPs' security teams about their thoughts) > > On Wed, Mar 6, 2024 at 5:51 PM Nicolás Peña <n...@chromium.org> wrote: > > No, Sec-Fetch-Dest > <https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Sec-Fetch-Dest> > is not changing. Sec-Fetch-Mode > <https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Sec-Fetch-Mode> > is. > > On Wednesday, March 6, 2024 at 11:31:35 AM UTC-5 Chris Harrelson wrote: > > On Wed, Mar 6, 2024 at 8:28 AM Nicolás Peña <n...@chromium.org> wrote: > > > > On Wednesday, March 6, 2024 at 5:11:09 AM UTC-5 Yoav Weiss wrote: > > On Wed, Mar 6, 2024 at 10:21 AM Yoav Weiss (@Shopify) < > yoav...@chromium.org> wrote: > > > > On Mon, Mar 4, 2024 at 9:36 PM Mike Taylor <mike...@chromium.org> wrote: > > LGTM1 > On 3/4/24 1:33 PM, Nicolás Peña wrote: > > Contact emails > > n...@chromium.org > > Explainer > > https://github.com/fedidcg/FedCM/issues/428 > > > A few lines summarizing this issue would be most useful when evaluating > this and understanding what y'all want to ship. > In particular, it'd be useful to understand the request flow, what is the > request's origin (as IIUC, we're talking about requests issued from the > browser), and what is the request destination that we may want IDPs to > check. > > Examples of the checks IDPs would have to make would also be helpful. > > > Sure! From the spec > <https://fedidcg.github.io/FedCM/#idp-api-id-assertion-endpoint>, here is > a sample request: > > POST /fedcm_assertion_endpoint HTTP/1.1 > Host: idp.example > Origin: https://rp.example/ > Content-Type: application/x-www-form-urlencoded > Cookie: 0x23223 > Sec-Fetch-Dest: webidentity > account_id=123&client_id=client1234&nonce=Ct60bD&disclosure_ > text_shown=true > > With this change, Sec-Fetch-Mode will now be cors in this request and the > IDP is expected to return the following in the response (no preflight is > performed): > > > Do you mean Sec-Fetch-Dest? > > > > Access-Control-Allow-Origin: https://rp.example/ > Access-Control-Allow-Credentials: true > > > > Also, is the "identity assertion" endpoint the same as the token endpoint > <https://github.com/fedidcg/FedCM/blob/main/explainer.md#token_endpoint>? > > > Yea. I think that explainer doc is not super up to date. > > > > Specification > > https://github.com/fedidcg/FedCM/pull/547 > > Summary > > The fetches in the FedCM API are hard to reason about because of the > properties required of them. While there is ongoing discussion regarding > the accounts endpoint, there is broad consensus that the ID assertion > endpoint should use CORS. This aligns security properties of this fetch > more closely to other fetches in the web platform. > > Blink component > > Blink>Identity>FedCM > <https://g-issues.chromium.org/issues?q=status:open%20componentid:1456331&pli=1&authuser=0> > > TAG review > > Not requesting a TAG review. We have already had extensive discussions > with Fetch experts. > > TAG review status > > N/A > > Risks > > Interoperability and Compatibility > > This is a backwards incompatible feature, but one that is warranted due to > consensus reached by our security reviewers as well as other browser vendor > engineers. We have a manageable list of IDPs that we know are using the > FedCM API and we have reached out to all IDPs that are currently deploying > FedCM to make sure that they won’t break with this change. > > > Gecko: Positive based on TPAC discussions and https://github.com/fedidcg/ > FedCM/issues/428. Not filing a standards position request for small > additions at the explicit request from Firefox (they prefer PRs). > > WebKit: Positive based on TPAC discussions and https://github.com/fedidcg/ > FedCM/issues/428. Recently, standards position requests for smaller FedCM > features have been closed, pointing to the (unresolved) main FedCM one in > https://github.com/WebKit/standards-positions/issues/309 so not filing > one for this. > > Web developers: No signals > > Other signals: > > Ergonomics > > N/A > > > Activation > > N/A > > > Security > > By adding CORS, we add a check that the IDP explicitly agrees for the > browser to share the ID assertion response to the RP. In addition, having > this fetch align with most other credentialed fetches in the browser means > that any future protections are received by default, and we do not have to > special case this fetch. > > > 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 > > We surface errors when there is a network problem with the ID assertion > fetch. This will help developers understand when this feature introduces a > problem in their FedCM calls. > > > Will this feature be supported on all six Blink platforms (Windows, Mac, > Linux, ChromeOS, Android, and Android WebView)? > > No. FedCM is not supported on Android WebView. > > Is this feature fully tested by web-platform-tests > <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md> > ? > > https://wpt.fyi/results/credential-management/fedcm-identity > -assertion-nocors.https.html?label=experimental&label=master&aligned > (will pass on Chrome once we ship) > > Flag name on chrome://flags > > None > > Finch feature name > > FedCmIdAssertionCORS > > Requires code in //chrome? > > True (because FedCM API does) > > Tracking bug > > https://issues.chromium.org/issues/40284123 > > Estimated milestones > > DevTrial on desktop > > 120 > > > DevTrial on Android > > 120 > > We want to ship on M124 > > Anticipated spec changes > > Open questions about a feature may be a source of future web compat or > interop issues. Please list open issues (e.g. links to known github issues > in the project for the feature specification) whose resolution may > introduce web compat/interop risk (e.g., changing to naming or structure of > the API in a non-backward-compatible way). > > https://github.com/whatwg/fetch/issues/1637 > > Link to entry on the Chrome Platform Status > > https://chromestatus.com/feature/5094763339710464 > > 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/ch > romium.org/d/msgid/blink-dev/1814484e-4a0c-4210-b936-29ead46 > f32c5n%40chromium.org > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/1814484e-4a0c-4210-b936-29ead46f32c5n%40chromium.org?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/ch > romium.org/d/msgid/blink-dev/91c26d40-ccc9-4abe-bf97-38cd9e4 > 8f684%40chromium.org > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/91c26d40-ccc9-4abe-bf97-38cd9e48f684%40chromium.org?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+...@chromium.org. > > To view this discussion on the web visit https://groups.google.com/a/ch > romium.org/d/msgid/blink-dev/a349c863-9904-491f-9e9d-3122768 > 3d4ffn%40chromium.org > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/a349c863-9904-491f-9e9d-31227683d4ffn%40chromium.org?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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