LGTM1, but conditioned on the spec work landing before shipping anything.
On 6/25/25 1:00 a.m., Yoav Weiss (@Shopify) wrote:
On Wed, Jun 25, 2025 at 4:18 AM Vladimir Levin <vmp...@chromium.org> wrote:On Thursday, June 19, 2025 at 9:48:37 AM UTC-4 Yoav Weiss wrote: Contact emailsyoavwe...@chromium.org Explainer This will add the cookie name prefix `__Http-`. Cookies that would start with that prefix would only be able to be set using the `Set-Cookie` HTTP header and will have to have an `httpOnly` attribute. Adding that prefix to the cookie name will give site operators the guarantee that any such cookie they see was set by their server, and not be a malicious/compromised script. There are still ongoing discussions <https://github.com/httpwg/http-extensions/issues/3111#issuecomment-2986560222> about the exact spelling of a combination of this prefix with the `__Host-` prefix. I'd like this intent to cover both, but I'm not planning to ship the `__HostHttp` variant until the dust settles on the desired spelling. Specificationhttps://github.com/httpwg/http-extensions/pull/3110 <https://github.com/httpwg/http-extensions/pull/3110> Summary There are cases where it's important to distinguish on the server side between cookies that were set by the server and ones that were set by the client. One such case is cookies that are normally always set by the server, unless some unexpected code (an XSS exploit, a malicious extension, a commit from a confused developer, etc.) happens to set them on the client. This proposal adds a signal that would enable servers to make such a distinction. More specifically, it defines the __Http and __HostHttp prefixes, that make sure that a cookie is not set on the client side using script. What is the behavior if one attempts to set an `__Http`-prefixed cookie from script with this feature? Does it silently fail, or is there an error that is thrown?Similar to existing prefixes <https://github.com/web-platform-tests/wpt/blob/master/cookies/resources/cookie-helper.sub.js#L76>, when setting a cookie using `document.cookie`, the only way to know it failed is observing (on the server) it is not present in relevant requests. Setting such a cookie through the CookieStore API results in a Promise rejection <https://github.com/web-platform-tests/wpt/blob/master/cookie-store/cookieStore_special_names.https.any.js#L39>.Blink componentInternals>Network>Cookies <https://issues.chromium.org/issues?q=customfield1222907:%22Internals%3ENetwork%3ECookies%22> TAG reviewNone, as the TAG doesn't typically review HTTP features. TAG review statusNot applicable Risks Interoperability and Compatibility No particular compat issues, as we don't expect this prefix to already exist in the wild. In terms of interop, Mozilla and Apple folks are heavily involved in the discussions and haven't raised any concerns. I agree that the chance of there being __Http named cookies is very low, but I've been wrong about things like this before :) Do you have any metrics/code searches/etc to validate that this is safe from compat perspective?I don't have any metrics, and GH search seems to ignore the _ and - parts when searching for `__Http-`.. I agree there's a non-zero change that someone added such a prefix to a cookie (without it being httpOnly), but I think having a Finch flag to be able to turn the feature off in case that turns out to be the case is sufficient./Gecko/: No signal (https://github.com/mozilla/standards-positions/issues/1256 <https://github.com/mozilla/standards-positions/issues/1256>) /WebKit/: No signal (https://github.com/WebKit/standards-positions/issues/518 <https://github.com/WebKit/standards-positions/issues/518>) /Web developers/: Positive (https://lists.w3.org/Archives/Public/ietf-http-wg/2025JanMar/0146.html <https://lists.w3.org/Archives/Public/ietf-http-wg/2025JanMar/0146.html>) /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 Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?Yes Is this feature fully tested by web-platform-tests <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?Yes https://chromium-review.googlesource.com/c/chromium/src/+/6638647/15/third_party/blink/web_tests/external/wpt/cookies/prefix/__Http.https.html <https://chromium-review.googlesource.com/c/chromium/src/+/6638647/15/third_party/blink/web_tests/external/wpt/cookies/prefix/__Http.https.html> https://chromium-review.googlesource.com/c/chromium/src/+/6650996/2/third_party/blink/web_tests/external/wpt/cookies/prefix/__HostHttp.https.html <https://chromium-review.googlesource.com/c/chromium/src/+/6650996/2/third_party/blink/web_tests/external/wpt/cookies/prefix/__HostHttp.https.html> Flag name on about://flagsNone Finch feature namePrefixCookieHttp, PrefixCookieHostHttp Rollout planWill ship enabled for all users Requires code in //chrome?False Tracking bughttps://issues.chromium.org/issues/426096760 <https://issues.chromium.org/issues/426096760> Estimated milestonesShipping on desktop140Shipping on Android140Shipping on WebView140 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). None Link to entry on the Chrome Platform Statushttps://chromestatus.com/feature/5170139586363392?gate=5174068239925248 <https://chromestatus.com/feature/5170139586363392?gate=5174068239925248> 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. 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