On Fri, Sep 3, 2021 at 4:55 AM Yoav Weiss <yoavwe...@chromium.org> wrote:
> Hey Andrew, > > Given that the metrics are not a superset of what you're trying to > deprecate, could you please add CountDeprecation > <https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/core/frame/deprecation.cc;drc=f6f22e82bcd0d50f390b23ee9688c58de5ae0bdc;bpv=1;bpt=1;l=702?q=deprecation&ss=chromium> > metrics of the case you are intending to deprecate? That would ensure .e.g > deprecation reports are sent to folks that happen to have such cookies. > Even though you haven't really asked, from my perspective, it's also fine > to add a console deprecation message at this point, in parallel to the > metrics. > FYI, CountDeprecation will take care of adding that console message for you, as well as: - Generating a report object which can be seen with a ReportingObserver, - Sending that report to any configured endpoints for the document, and - Counting the usage for UMA, so that we can track the (hopefully) declining usage of the deprecated feature. Ian > Cheers :) > Yoav > > On Wednesday, September 1, 2021 at 5:05:44 PM UTC+2 Andrew Williams wrote: > >> Here is the percentage for the metric mentioned in my last email: over a >> 7 day period, 0.00004% of cookies seen in the stable version of Chrome had >> truncated names and/or values. >> >> Ultimately our plan is to ship this feature behind a kill switch that we >> could flip if major issues are reported. With that in mind, and given the >> low number of truncated cookie names/values observed via our existing >> metrics, would it make sense to implement and collect the new metrics in >> parallel with rolling out the changes described in this I2P&S? Or do you >> think taking the more cautious approach and implementing/collecting the new >> metrics before landing this change is a better way forward (despite taking >> more time)? >> >> -Andrew >> >> On Fri, Aug 27, 2021 at 1:45 PM Andrew Williams <awil...@chromium.org> >> wrote: >> >>> Thanks for the feedback/questions Yoav and Daniel. >>> >>> We have some metrics >>> <https://source.chromium.org/chromium/chromium/src/+/700dc7fe1578ab5e0e50a6304f2a1960005b8f8b:tools/metrics/histograms/metadata/cookie/histograms.xml;l=56;bpv=1;bpt=0> >>> on Chrome's existing behavior to truncate cookie lines containing \x00, >>> \x0d, and \x0a (specifically, in cases where the truncation affects the >>> cookie name or the cookie value). The percentage of cookies with truncated >>> names or values is quite low, although I'm still waiting on approval to >>> release the exact percentage. We don't have any metrics for cases where >>> truncation affected cookie attribute parsing (for example, the malicious >>> case this intent aims to address) or where truncation was harmless (for >>> example, a newline as the last character in the cookie line), though. >>> Especially for the latter case, it does seem plausible that certain sites >>> could be constructing cookie lines in such a way that control characters >>> slip in unnoticed. We will add new metrics to cover these cases so that we >>> can better predict the level of breakage that these changes may have. >>> >>> -Andrew >>> >>> On Thu, Aug 26, 2021 at 2:22 PM Daniel Bratell <bratel...@gmail.com> >>> wrote: >>> >>>> Even if browsers are currently slightly incompatible, it seems this >>>> change will short term make them more incompatible. As Yoav said, it would >>>> be good to have an idea about how common this is, i.e. how often will >>>> cookies that are today truncated instead be rejected? >>>> >>>> /Daniel >>>> >>>> On 2021-08-25 16:18, Yoav Weiss wrote: >>>> >>>> Hey Andrew! Thanks for working on this, this seems like a significant >>>> compatibility gap (with security implications) that would be great to >>>> close. >>>> >>>> On Tuesday, August 24, 2021 at 3:45:50 PM UTC+2 Andrew Williams wrote: >>>> >>>>> Contact emails awil...@chromium.org, miketa...@chromium.org Explainer >>>>> >>>>> https://github.com/httpwg/http-extensions/issues/1531 >>>>> >>>>> https://github.com/httpwg/http-extensions/pull/1589 >>>>> >>>>> Specification >>>>> >>>>> >>>>> https://github.com/httpwg/http-extensions/blob/main/draft-ietf-httpbis-rfc6265bis.md >>>>> >>>>> Summary >>>>> >>>>> Updates how control characters in cookie data are handled. >>>>> Specifically, the tab character is now permitted, but all other control >>>>> characters cause the entire cookie to be rejected (previously the \x00, >>>>> \x0D, and \x0A characters in a cookie line caused it to be truncated >>>>> instead of rejected entirely, which could have enabled malicious behavior >>>>> in certain circumstances). This behavior is also in line with the latest >>>>> drafts of RFC6265bis. >>>>> Blink component >>>>> >>>>> Internals>Network>Cookies >>>>> <https://bugs.chromium.org/p/chromium/issues/list?q=component:Internals%3ENetwork%3ECookies> >>>>> >>>>> Motivation >>>>> >>>>> In the case where attacker controlled data is used to set a new >>>>> cookie, having certain control characters truncate the cookie line could >>>>> result in security-related cookie attributes being ignored. This behavior >>>>> may also lead to cookie data corruption when control characters are >>>>> introduced, which may cause unpredictable behavior on the application side >>>>> (more so than cookies not being set, which is a case that applications >>>>> should already handle). Having control characters result in the whole >>>>> cookie being rejected helps mitigate these concerns and aligns Chrome with >>>>> RFC6265bis. For the tab character, although it falls in the control >>>>> character range (\x00 - \x1F, \x7F), it’s a printable character and >>>>> allowed >>>>> by other browsers. Treating it the same way that the space character is >>>>> treated makes sense intuitively, eliminates a potential fingerprinting >>>>> vector, and aligns Chrome with RFC6265bis. >>>>> >>>> >>>> In the past, moving to a stricter models that forbade certain >>>> characters resulted in at least some breakage of non-malicious content. I >>>> doubt this one would be significantly different. >>>> Do you have a sense of the resulting breakage? If not, I think it'd >>>> make sense to add metrics to our cookie parsing algorithm and see what that >>>> breakage would look like. >>>> >>>> >>>>> Initial public proposal TAG review >>>>> >>>>> N/A >>>>> <https://groups.google.com/a/chromium.org/g/blink-api-owners-discuss/c/uBxq9uCpKx0/m/A5LI0NbyAAAJ>: >>>>> this change is already specified in RFC 6265bis and is a relatively minor >>>>> change to what's already implemented in Chrome (to improve spec >>>>> compliance). >>>>> >>>> >>>> I agree that this change is in lower layers than those the TAG usually >>>> deals with. >>>> >>>> >>>>> TAG review status Not applicable >>>>> Risks >>>>> >>>>> N/A >>>>> Interoperability and Compatibility >>>>> >>>>> WebKit / Safari: >>>>> >>>>> - All control characters except the tab character cause the cookie to >>>>> be rejected if present in the name and cause the rest of the cookie line >>>>> to >>>>> be truncated if present in the value >>>>> >>>>> >>>>> >>>>> Gecko / Firefox: >>>>> >>>>> - 0x00 in the cookie value causes the rest of the value to be >>>>> truncated (but subsequent attributes are preserved) >>>>> >>>>> - 0x00 in the cookie name causes the rest of the name and the value >>>>> to be truncated (but subsequent attributes are preserved) >>>>> >>>>> - 0x0d and 0x0a cause the entire cookie line to be truncated >>>>> (attributes ignored) >>>>> >>>>> - 0x01 through 0x09 (the tab character), 0x0b through 0x0c, and 0x0e >>>>> through 0x1f cause the cookie to be rejected if they are present in the >>>>> name, but are allowed in the cookie value >>>>> >>>>> - 0x7f is allowed in the cookie name and cookie value >>>>> >>>>> >>>>> >>>>> The following issues exist reporting these differences: >>>>> >>>>> - >>>>> >>>>> Firefox - https://bugzilla.mozilla.org/show_bug.cgi?id=1702031#c1 >>>>> - >>>>> >>>>> WebKit - https://bugs.webkit.org/show_bug.cgi?id=229088 >>>>> >>>>> >>>>> >>>>> Allowing tab characters in cookie names aligns Chrome with Safari but >>>>> not Firefox, and allowing tabs in the cookie value aligns Chrome with >>>>> both. >>>>> >>>>> >>>>> >>>>> Regarding control characters (not including tab), what will change in >>>>> Chrome is the handling of 0x00, 0x0d, and 0x0a characters. Today, Chrome >>>>> truncates cookie lines when these characters are encountered, and this >>>>> intent proposes having these characters result in cookie rejection >>>>> instead. Rejecting cookie names containing these characters aligns Chrome >>>>> with Safari but not Firefox, but rejecting cookie values containing these >>>>> characters is inconsistent with existing Safari or Firefox behavior. >>>>> However, these changes unify Chrome’s control character handling behavior, >>>>> better align Chrome with RFC6265bis, and also help prevent a class of >>>>> cookie attribute removal attacks (when malicious input is used to build a >>>>> cookie line under certain conditions). >>>>> >>>>> >>>>> >>>>> Gecko: N/A - these changes seem too small to justify this effort WebKit: >>>>> N/A - these changes seem too small to justify this effort >>>>> >>>> >>>> I somewhat agree that asking for a position here would be an overkill, >>>> but would love to get a signal from both Mozilla and Safari on their >>>> intents to align with the RFC. (the former seems more likely than the >>>> latter, as this seems like a CFNetwork issue) >>>> At the same time, the issues seem sufficient for that purpose, assuming >>>> folks there respond. >>>> >>>> Web developers: N/A - these changes are relatively small and are in >>>>> alignment with the RFC, other browsers, and/or existing behavior >>>>> >>>> >>>> Yeah, developers are unlikely to be happy about this from a breakage >>>> perspective, even if it'd reduce compat issues. The main thing we can do >>>> about that is ensure breakage is minimal before shipping. >>>> >>>> >>>>> Debuggability >>>>> >>>>> DevTools debugging support will be implemented along with this change. >>>>> Rejected response cookies are already shown in DevTools in the Network >>>>> panel, with a status explaining why they were rejected. Another status >>>>> will >>>>> be added to annotate cookies rejected due to control characters. >>>>> >>>>> Is this feature fully tested by web-platform-tests >>>>> <https://chromium.googlesource.com/chromium/src/+/master/docs/testing/web_platform_tests.md> >>>>> ? >>>>> >>>>> In Progress - >>>>> https://chromium-review.googlesource.com/c/chromium/src/+/3084521 >>>>> Flag name >>>>> >>>>> UpdatedCookieControlCharacterChecks >>>>> Requires code in //chrome? >>>>> >>>>> False >>>>> Tracking bug >>>>> >>>>> https://bugs.chromium.org/p/chromium/issues/detail?id=1233602 >>>>> >>>>> Estimated milestones >>>>> >>>>> M96 >>>>> Link to entry on the Chrome Platform Status >>>>> >>>>> https://www.chromestatus.com/feature/5709264560586752 >>>>> >>>>> Requesting approval to ship? >>>>> >>>>> Yes >>>>> >>>>> This intent message was generated by Chrome Platform Status >>>>> <https://www.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/chromium.org/d/msgid/blink-dev/e2de8b96-8878-47fe-99e2-5497b96c9adcn%40chromium.org >>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/e2de8b96-8878-47fe-99e2-5497b96c9adcn%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/chromium.org/d/msgid/blink-dev/44805dc7-edd8-218d-dcbe-9c589509b633%40gmail.com >>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/44805dc7-edd8-218d-dcbe-9c589509b633%40gmail.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 on the web visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/fcb32661-cecb-4f5a-a29d-9f3cdfbc5395n%40chromium.org > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/fcb32661-cecb-4f5a-a29d-9f3cdfbc5395n%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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