- From: Emily Stark <estark@google.com>
- Date: Wed, 21 Nov 2018 14:04:16 -0800
- To: Eric Rescorla <ekr@rtfm.com>
- Cc: iesg@ietf.org, httpbis-chairs@ietf.org, Mark Nottingham <mnot@mnot.net>, draft-ietf-httpbis-expect-ct@ietf.org, httpbis <ietf-http-wg@w3.org>
- Message-ID: <CAPP_2Sa5U1PZ2W-jW4gq3W7D9-ayxW5dq8LQhh5SvcLLQgYDvA@mail.gmail.com>
Sorry for the delay. I'm on maternity leave but hope to have these addressed in the next couple weeks. On Wed, Nov 21, 2018 at 1:52 PM Eric Rescorla <ekr@rtfm.com> wrote: > Following up, I don't see any response to these comments. > > -Ekr > > > On Thu, Sep 13, 2018 at 7:22 AM Eric Rescorla <ekr@rtfm.com> wrote: > >> I have one other non-blocking comment: Why is this document Experimental? >> People are already deploying CT without this. It seems like PS would make >> more sense or Informational. >> >> Alexey, I leave it to you. >> -Ekr >> >> >> On Wed, Sep 12, 2018 at 4:12 PM, Eric Rescorla <ekr@rtfm.com> wrote: >> >>> Eric Rescorla has entered the following ballot position for >>> draft-ietf-httpbis-expect-ct-07: Discuss >>> >>> When responding, please keep the subject line intact and reply to all >>> email addresses included in the To and CC lines. (Feel free to cut this >>> introductory paragraph, however.) >>> >>> >>> Please refer to >>> https://www.ietf.org/iesg/statement/discuss-criteria.html >>> for more information about IESG DISCUSS and COMMENT positions. >>> >>> >>> The document, along with other ballot positions, can be found here: >>> https://datatracker.ietf.org/doc/draft-ietf-httpbis-expect-ct/ >>> >>> >>> >>> ---------------------------------------------------------------------- >>> DISCUSS: >>> ---------------------------------------------------------------------- >>> >>> Rich version of this review at: >>> https://mozphab-ietf.devsvcdev.mozaws.net/D4579 >>> >>> >>> This generally seems like a sound mechanism, but I believe there are >>> some points here that are sufficiently unclear they might create >>> interop problems,s o I am balloting DISCUSS. >>> >>> Most importantly, this document just says you support CT, but that >>> creates a potential interop problem if say 6962-tris had a different >>> way of delivering CT information or a different syntax. I'm not saying >>> you need a version here, but you need to indicate that it's not >>> forward-looking. >>> >>> Also, see below. >>> >>> DETAIL >>> S 2.4. >>> > beginning an HTTP conversation over the TLS channel. >>> > >>> > If a connection to a Known Expect-CT Host violates the UA's CT >>> policy >>> > (i.e., the connection is not CT-qualified), and if the Known >>> Expect- >>> > CT Host's Expect-CT metadata indicates an "enforce" configuration, >>> > the UA MUST treat the CT compliance failure as an error. >>> >>> Is this supposed to be a hard failure, as with HSTS. If not, how does >>> it interact with HSTS's hard failure reqs. >>> >>> >>> S 3.1. >>> > (This may differ from the value of the >>> "served-certificate-chain" >>> > key.) The value is provided as an array of strings, which MUST >>> > appear in the order matching the chain that the UA validated; >>> each >>> > string in the array is the Privacy-Enhanced Mail (PEM) >>> > representation of each X.509 certificate as described in >>> > [RFC7468]. >>> >>> What happens if you try to construct multiple paths? >>> >>> >>> S 3.1. >>> > does not have or does not trust the public key of the log >>> from >>> > which the SCT was issued), "valid" (indicating that the UA >>> > successfully validated the SCT as described in Section 5.2 >>> of >>> > [RFC6962] or Section 8.2.3 of >>> [I-D.ietf-trans-rfc6962-bis]), or >>> > "invalid" (indicating that the SCT validation failed because >>> > of, e.g., a bad signature). >>> >>> Is "invalid" anything other than the specific cases listed above? >>> >>> >>> ---------------------------------------------------------------------- >>> COMMENT: >>> ---------------------------------------------------------------------- >>> >>> >>> > allows web host operators to instruct user agents to expect valid >>> > Signed Certificate Timestamps (SCTs) to be served on connections >>> to >>> > these hosts. Expect-CT allows web host operators to discover >>> > misconfigurations in their Certificate Transparency deployments >>> and >>> > ensure that misissued certificates accepted by UAs are >>> discoverable >>> > in Certificate Transparency logs. >>> >>> I don't believe that it does this. Consider a client which simply did >>> not support CT, then it would (a) accept a misissued certificate that >>> (b) was not discoverable >>> >>> >>> S 2.1.1. >>> > >>> > Figure 2: Syntax of the report-uri directive value >>> > >>> > "absolute-URI" is defined in Section 4.3 of [RFC3986]. >>> > >>> > Hosts may set "report-uri"s that use HTTP or HTTPS. If the >>> scheme in >>> >>> Why are you allowing HTTP? >>> >>> >>> S 2.3.2. >>> > the "enforce", "max-age", or "report-uri" header field value >>> > directives convey information different from that already >>> > maintained by the UA. If the "max-age" directive has a value >>> of >>> > 0, the UA MUST remove its cached Expect-CT information if the >>> host >>> > was previously noted as a Known Expect-CT Host, and MUST NOT >>> note >>> > this host as a Known Expect-CT Host if it is not already noted. >>> >>> As noted above, I think you need to clear the cache when you upgrade >>> to a potentially incompatible CT version, or otherwise reconfigure the >>> client. >>> >>> >>> S 2.3.2.1. >>> > this host as a Known Expect-CT Host if it is not already noted. >>> > >>> > 2.3.2.1. Noting Expect-CT >>> > >>> > Upon receipt of the Expect-CT response header field over an error- >>> > free TLS connection (including the validation adding in Section >>> 2.4), >>> >>> s/adding/added/? >>> >>> >>> S 2.3.2.1. >>> > host's domain name and its associated Expect-CT directives in non- >>> > volatile storage. >>> > >>> > To note a host as a Known Expect-CT Host, the UA MUST set its >>> Expect- >>> > CT metadata given in the most recently received valid Expect-CT >>> > header field, as specified in Section 2.3.2.2. >>> >>> This seems ungrammatical. Set it where? >>> >>> >>> S 2.3.2.2. >>> > >>> > 2.3.2.2. Storage Model >>> > >>> > If the substring matching the host production from the Request-URI >>> > (of the message to which the host responded) does not congruently >>> > match an existing Known Expect-CT Host's domain name, per the >>> >>> I would say "exactly match" rather than "congruently match" unless >>> this ia term of art somewhere. >>> >>> >>> S 2.3.2.2. >>> > understands them, the UA MAY note them as well. >>> > >>> > UAs MAY set an upper limit on the value of max-age, so that UAs >>> that >>> > have noted erroneous Expect-CT hosts (whether by accident or due >>> to >>> > attack) have some chance of recovering over time. If the server >>> sets >>> > a max-age greater than the UA's upper limit, the UA MAY behave as >>> if >>> >>> This MAY seems out of place, given that you already said MAY. >>> >>> >>> S 2.4. >>> > >>> > When a UA connects to a Known Expect-CT Host using a TLS >>> connection, >>> > if the TLS connection has no errors, then the UA will apply an >>> > additional correctness check: compliance with a CT Policy. A UA >>> > should evaluate compliance with its CT Policy whenever connecting >>> to >>> > a Known Expect-CT Host, as soon as possible. However, the check >>> can >>> >>> What does "as soon as possible" mean? >>> >>> >>> S 2.4. >>> > terminates the connection due to an Expect-CT failure, this could >>> > cause the UA to skip subsequent correctness checks. When the CT >>> > compliance check is skipped or bypassed, Expect-CT reports >>> > (Section 3) will not be sent. >>> > >>> > When CT compliance is evaluted for a Known Expect-CT Host, the UA >>> >>> Nit: evaluated >>> >>> >>> S 2.4.1. >>> > "report-uri" (Section 3). >>> > >>> > 2.4.1. Skipping CT compliance checks >>> > >>> > It is acceptable for a UA to skip CT compliance checks for some >>> hosts >>> > according to local policy. For example, a UA may disable CT >>> >>> Should this be MAY? >>> >>> >>> S 3.1. >>> > >>> > o "scts": the value represents the SCTs (if any) that the UA >>> > received for the Expect-CT host and their validation statuses. >>> > The value is provided as an array of JSON objects. The SCTs >>> may >>> > appear in any order. Each JSON object in the array has the >>> > following keys: >>> >>> So these just apply to the EE cert? What about CT for the non-EE >>> certs? >>> >>> >>> >>> >>> S 3.1. >>> > of, e.g., a bad signature). >>> > >>> > * The "source" key, with a string value that indicates from >>> where >>> > the UA obtained the SCT, as defined in Section 3 of >>> [RFC6962] >>> > and Section 6 of [I-D.ietf-trans-rfc6962-bis]. The UA MUST >>> set >>> > the value to one of "tls-extension", "ocsp", or "embedded". >>> >>> What do these mean? They seem obvious, but you don't say. >>> >>> >>> >>
Received on Wednesday, 21 November 2018 22:04:51 UTC