On Wednesday, January 15, 2025 at 5:25:48 PM UTC+1 Chris Harrelson wrote: Please also fill out the various reviews in your chromestatus entry (privacy, security, enterprise, debuggability, testing).
On Tue, Jan 14, 2025 at 2:43 PM 'Liang Zhao (REDMOND)' via blink-dev <blink-dev@chromium.org<mailto:blink-dev@chromium.org>> wrote: From: Mike Taylor <miketa...@chromium.org<mailto:miketa...@chromium.org>> Sent: Tuesday, January 14, 2025 7:10 AM To: Liang Zhao (REDMOND) <liang.z...@microsoft.com<mailto:liang.z...@microsoft.com>>; blink-dev@chromium.org<mailto:blink-dev@chromium.org> Cc: hirosh...@chromium.org<mailto:hirosh...@chromium.org>; mk...@chromium.org<mailto:mk...@chromium.org> Subject: [EXTERNAL] Re: [blink-dev] Intent to Ship: Fire error event instead of throwing for CSP blocked worker You don't often get email from miketa...@chromium.org<mailto:miketa...@chromium.org>. Learn why this is important<https://aka.ms/LearnAboutSenderIdentification> On 1/13/25 5:19 PM, 'Liang Zhao (REDMOND)' via blink-dev wrote: Contact emails lz...@microsoft.com<mailto:lz...@microsoft.com> Explainer None I think an explainer (or even an inline text explaining the change, providing an example, etc) would have significantly helped folks understand what it is that you're trying to ship. Could you write something to that effect? When the url is blocked by Content Security Policy, script code “new Worker(url)” and “new SharedWorker(url)” currently throws exception. According to spec, the CSP check is done as part of fetch which happens asynchronously and the constructor should not throw. Instead an error event should fire after the object is returned. This feature aligns Chromium behavior with spec. Specification https://fetch.spec.whatwg.org/#concept-main-fetch This points at a relatively long algorithm. Can you point out the specific steps that are relevant here? Step 7 of the linked “main fetch” section. Updated the spec link in chromestatus to https://www.w3.org/TR/CSP3/#fetch-integration, which is a better place to understand that CSP check is part of fetch instead of details of how fetch is done in the fetch spec. Summary When blocked by CSP, Chromium currently throws SecurityError from constructor. Spec requires CSP to be checked as part of fetch and fires error event asynchronously. This aims to make Chromium spec conformant, which is not throwing during constructor and fires error event asynchronously. Which constructor? The constructor of Worker and SharedWorker objects. Also updated the chromestatus so that it is clear. An example demonstrating where developers need to catch those exceptions now would be helpful IMO. Before the change if developer wants to handle the worker being blocked failure, the code would be something like this: try { var worker = new Worker(url); … } catch (e) { // error handling code } After the change, the code would be something like this: var worker = new Worker(url); worker.addEventListener('error', function(event) { // error handling code }); … Blink component Blink>SecurityFeature>ContentSecurityPolicy<https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3ESecurityFeature%3EContentSecurityPolicy%22> TAG review None TAG review status Not applicable Risks Interoperability and Compatibility Are you able to expand on the compatibility implications for this change, i.e., do we know if Firefox has any site breakage as a result of their behavior? What scenarios might surprise developers who are relying on Chrome's current behavior, etc? We are not aware of any site breakage for Firefox due to its behavior. If a site has a worker that is blocked by CSP and has code after "new Worker()", those code currently does not run in Chrome or Safari, but runs in Firefox. After the change, those code would run in Chrome. Also, if sites are doing something as a result of catching a CSP failure exception, that would stop working (unless they shift to start listening to the relevant event), right? That is correct. If a site has code that runs upon catching SecurityError exception during new Worker()/SharedWorker(), those code would not run. Instead. if the site has error event listener, that event listener will run. Currently Firefox works as spec-ed while Safari works the same as Chrome. With the wrong test code in WPT tests, Firefox is failing the tests: https://wpt.fyi/results/content-security-policy/worker-src/dedicated-worker-src-child-fallback-blocked.sub.html?label=experimental&label=master&aligned https://wpt.fyi/results/content-security-policy/worker-src/shared-worker-src-child-fallback-blocked.sub.html?label=experimental&label=master&aligned After updating Chrome code and WPT tests, Firefox passes the tests while Safari fails the tests. Can you explain what you mean by wrong test code? The current WPT test code expects exception to throw, which is not what’s required by the spec. The test code has a TODO comment states that the test code is wrong with a link to https://crbug.com/663298, Gecko: Shipped/Shipping WebKit: No signal Have we asked for a signal from WebKit folks? Filed an issue at https://github.com/WebKit/standards-positions/issues/451. Web developers: No signals Other signals: This changes the behavior the same as Firefox. 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? Debuggability When worker is blocked by CSP, there is DevTools message logged about the blocking by CSP. This behavior is not changed. 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://wpt.fyi/results/content-security-policy/worker-src/dedicated-worker-src-child-fallback-blocked.sub.html?label=experimental&label=master&aligned https://wpt.fyi/results/content-security-policy/worker-src/shared-worker-src-child-fallback-blocked.sub.html?label=experimental&label=master&aligned Note that the test code currently has the wrong expectation and will be updated as part of this feature work. Flag name on about://flags None Finch feature name None Non-finch justification This is a simple change of behavior for uncommon scenario where worker is blocked by CSP, and the changed behavior is the same as Firefox and spec aligned. It is unlikely that a site depends on the current behavior of throwing exception for blocked worker. Can we back up "it is unlikely" with some data? Absent that, I would strongly suggest we put this behind a flag. Changed the plan to put this new behavior behind NoThrowForCSPBlockedWorker feature flag. Also updated the chromestatus. Requires code in //chrome? False Tracking bug https://issues.chromium.org/issues/41285169 Estimated milestones Shipping on desktop 134 DevTrial on desktop 134 Shipping on Android 134 DevTrial on Android 134 Shipping on WebView 134 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 Status https://chromestatus.com/feature/5177205656911872?gate=5108732671033344 -- 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<mailto:blink-dev+unsubscr...@chromium.org>. To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CO1PR00MB2285E0FC0FEC6768415E9F979E1F2%40CO1PR00MB2285.namprd00.prod.outlook.com<https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CO1PR00MB2285E0FC0FEC6768415E9F979E1F2%40CO1PR00MB2285.namprd00.prod.outlook.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<mailto:blink-dev+unsubscr...@chromium.org>. To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/BY1PR00MB2289751B22915D40E547832F9E182%40BY1PR00MB2289.namprd00.prod.outlook.com<https://groups.google.com/a/chromium.org/d/msgid/blink-dev/BY1PR00MB2289751B22915D40E547832F9E182%40BY1PR00MB2289.namprd00.prod.outlook.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 visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CO1PR00MB2285CDD0AF481085E4B4249C9E1B2%40CO1PR00MB2285.namprd00.prod.outlook.com.
