On Thu, Jun 19, 2025 at 12:10 AM Domenic Denicola <dome...@chromium.org> wrote:
> I believe this should be completely unobservable to web authors, right? > (Apart from maybe fewer or more network errors.) > > If so, I don't think this needs any LGTMs, as it fits well under the > Web-developer-facing > change to existing behavior > <https://www.chromium.org/blink/launching-features/#behavior-changes> > category. > (Which is... confusingly named > <https://github.com/GoogleChrome/chromium-dashboard/issues/5145>.) But, > in case it helps, LGTM1. > > On Thursday, June 19, 2025 at 12:12:34 AM UTC+9 Ari Chivukula wrote: > >> Contact emails >> >> aric...@chromium.org, awil...@chromium.org, miketa...@chromium.org >> Explainer >> >> None >> Specification >> >> None >> >> Summary >> >> This launch enables TCP port randomization on versions of Windows (2020 >> H1 or later) where we do not expect to see issues with re-use of prior >> ports occurring too fast (causing rejection due to timeouts on port >> re-use). The rapid port re-use issue arises from the Birthday problem >> <https://en.wikipedia.org/wiki/Birthday_problem>, where the probability >> of randomly re-picking a port already seen rapidly converges with 100% for >> each new port chosen when compared to port re-use in a sequential model. >> >> >> Blink component >> >> Blink>Network >> <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3ENetwork%22> >> >> TAG review >> >> None >> >> TAG review status >> >> Not applicable >> >> >> Motivation >> >> When port randomization is disabled (the default), sites are able to >> count the amount of connections opened by other tabs if they check the TCP >> port used for new connections before and after opening another window. This >> knowledge can be used to glean information about other sites like whether >> they are logged in or not. >> >> Risks >> >> Interoperability and Compatibility >> >> This launch only impacts Windows, and should not cause compatibility >> issues as Microsoft backported their port randomization fix >> <https://chromium-review.googlesource.com/c/chromium/src/+/5464674> to >> Windows 10, 2020 H1 and tested it in Edge. >> > Is it possible that we have users on versions >= 2020H1, < 2022H2 but who have not received the backported fix (e.g., because they have not installed the applicable update)? Would they encounter brokenness in Chrome? >> Chrome previously attempted to roll this out in 2021 but ran into (since >> resolved) issues where rapid port re-use caused network errors. >> >> Rollout on linux isn’t needed as port randomization is enabled by default >> while on macOS an issue similar to the one on Windows with rapid port >> re-use causing issues is still around. >> >> Gecko: Appears to inherit OS defaults >> <https://github.com/search?q=repo%3Amozilla-firefox%2Ffirefox+setsockopt&type=code&p=1> >> >> WebKit: Appears to inherit OS defaults >> <https://github.com/search?q=repo%3AWebKit%2FWebKit+setsockopt&type=code> >> >> Web developers: N/A >> >> Debuggability >> >> This will be gated behind the base::feature kTcpPortRandomizationWin, so >> if breakage is suspected that flag could be turned off to detect impact. >> For how to control feature flags, see this >> <https://source.chromium.org/chromium/chromium/src/+/main:base/feature_list.h;drc=159a65729cf8fca4d9f453d12d97ab6515360491;l=259> >> . >> >> Measurement >> >> The histogram Net.TCPSocket.PortReuseTimeWindows2.{IPType}.{Result} will >> be used to gauge whether port re-use timings fall too low, while >> Net.TcpConnectAttempt.Latency.{Result} will be used to detect increases in >> overall connection failure rates. >> >> Will this feature be supported on all six Blink platforms (Windows, Mac, >> Linux, ChromeOS, Android, and Android WebView)? >> >> No, just Windows >> >> Is this feature fully tested by web-platform-tests? >> >> No, as this is a blink networking focused change browser tests or unit >> tests are more likely. >> >> Flag name on about://flags >> >> None >> >> Finch feature name >> >> kTcpPortRandomizationWin >> >> Rollout plan >> >> This will be rolled out slowly to detect issues early and either change >> the version target or roll back. We don’t believe an experiment is needed >> or desired as the issues we saw before were not very prevalent, we likely >> need to go beyond 1% to get enough data on Windows to know if there’s still >> a problem. >> >> Requires code in //chrome? >> >> No >> >> Tracking bug >> >> https://crbug.com/40744069 >> >> Estimated milestones >> >> 139 >> >> Link to entry on the Chrome Platform Status >> >> https://chromestatus.com/feature/5106900286570496 >> >> -- > 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/5ac125fa-3adf-4193-a1ff-1bf28f2f6020n%40chromium.org > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/5ac125fa-3adf-4193-a1ff-1bf28f2f6020n%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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