LGTM3. Compat risk seems minimal (and yes likely below the bar needed for API owner approval, but more transparency doesn't hurt).
On Fri, Jun 20, 2025 at 12:25 AM 'Erik Anderson' via blink-dev < blink-dev@chromium.org> wrote: > There was no new API here and thus no API detection mechanism. It’s just a > bug fix that ensures sockets are not rapidly reused toward the beginning of > the available range. > > > > Even when the bug is present, most networks work fine; it’s stateful > off-device middleboxes that might not see that the connection got > terminated and then get confused by a new connection from the same source > port. The use of this port randomization flag was shipped before, even with > the Windows bug; it took a couple of major Chrome releases before it was > determined it should be turned back off. That was the right decision, but > that’s also an indication that the risk of extreme breakage is low. > > > > The bug fix shipped has shipped with the Windows monthly security update > at least as early as November 2023 (some releases earlier). At this point, > only a device that hasn’t taken a security update from Windows for 18+ > months would see the buggy behavior. I suppose if you wanted to be > extremely paranoid, you could look at the fourth version component on those > older versions to check for that update. Or just scoping to 22H2+ is > reasonable too. > > > > *From:* Ari Chivukula <aric...@chromium.org> > *Sent:* Thursday, June 19, 2025 6:50 PM > *To:* Will Harris <w...@chromium.org>; Erik Anderson < > erik.ander...@microsoft.com> > *Cc:* Jeremy Roman <jbro...@chromium.org>; Domenic Denicola < > dome...@chromium.org>; blink-dev <blink-dev@chromium.org>; Andrew > Williams <awil...@chromium.org>; Mike Taylor <miketa...@chromium.org> > *Subject:* [EXTERNAL] Re: [blink-dev] Re: Intent to Ship: Randomizing TCP > Port Allocation on Windows > > > > Not to my knowledge, but I'm adding @erik.ander...@microsoft.com > <erik.ander...@microsoft.com> in case there is something I missed. > > > > I'm fine with starting with 22H2+ only for now, and adding 20H1+ only if > there's a reliable way to detect the fix or metrics on fix rollout % that > are convincing. > > > > ~ Ari Chivukula (Their/There/They're) > > > > On Thu, Jun 19, 2025, 14:21 Will Harris <w...@chromium.org> wrote: > > in general, it's preferable to do a capability test via an OS API rather > than simply gate on Windows version. Does the new API that Microsoft added > (and backported) provide a way for the OS to signal that this > better/working API is available? > > > > Will > > > > On Thu, Jun 19, 2025 at 11:15 AM Ari Chivukula <aric...@chromium.org> > wrote: > > That's probably possible, though hopefully they have installed system > updates in the past year. We could just target 2022H2 and later if needed. > > > > ~ Ari Chivukula (Their/There/They're) > > > > > > On Thu, Jun 19, 2025 at 10:54 AM Jeremy Roman <jbro...@chromium.org> > wrote: > > > > > > 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. > 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/CAGpy5DJXMP6tCc8KFK_sC07jAbxuX7e%3Dz2sBS-L%2BPU790vafdg%40mail.gmail.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAGpy5DJXMP6tCc8KFK_sC07jAbxuX7e%3Dz2sBS-L%2BPU790vafdg%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 visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAGpy5DL_yey6QTmOv2mSx-uSyvTHebqDt3s3sm_KMxRZwKSqaA%40mail.gmail.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAGpy5DL_yey6QTmOv2mSx-uSyvTHebqDt3s3sm_KMxRZwKSqaA%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 visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CH3PR00MB2435EDBEB1E8700F82B37597F47CA%40CH3PR00MB2435.namprd00.prod.outlook.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CH3PR00MB2435EDBEB1E8700F82B37597F47CA%40CH3PR00MB2435.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. 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