> On 10 Mar 2022, at 01:46, Benjamin Kaduk via Datatracker <[email protected]> > wrote: > > Benjamin Kaduk has entered the following ballot position for > draft-ietf-dprive-dnsoquic-10: 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/about/groups/iesg/statements/handling-ballot-positions/ > for more information about how to handle DISCUSS and COMMENT positions. > > > The document, along with other ballot positions, can be found here: > https://datatracker.ietf.org/doc/draft-ietf-dprive-dnsoquic/ > >
Hi Ben, Many thanks for the comments and further feedback - please see the updates in version -11 which was just published, which we hope addresses your comments. The issue containing discussion of your comments is : https://github.com/huitema/dnsoquic/issues/156 and the PR with final changes and some further discussion is https://github.com/huitema/dnsoquic/pull/166. Best regards Sara. > > ---------------------------------------------------------------------- > DISCUSS: > ---------------------------------------------------------------------- > > I have a 0-RTT-related topic that I'd like to discuss, as the current > situation isn't entirely clear to me. In particular, TLS 1.3 provides > (and QUIC inherits) a mechanism for a server to advertise that it just > does not support 0-RTT at all, via the (absence of the) "early_data" > extension. This meshes nicely with the guidance in RFC 8446 that 0-RTT is > to only be used cautiously, and only with specific request from the > application. However, this specificiation diverges from that requirement > for application opt-in (per §9.1), and so when I read the directive in > §5.5 that "servers MUST adopt one of the following behaviors", I am forced > to wonder if the absence of a "abort the connection, because you do not > enable early data at all" option is intended to forbid a server from > taking that approach and thus require servers to implement and enable > 0-RTT at runtime. > I hope that the intent was just for the §5.5 listing to be predicated on > the server using 0-RTT at all, but it's hard to reach that conclusion from > the existing text, so I have to seek clarification. > > > ---------------------------------------------------------------------- > COMMENT: > ---------------------------------------------------------------------- > > Thanks to Phillip Hallam-Baker for the secdir review. I did want to > reiterate one of his comments, regarding the potential for harmful > interaction between use of DoQ (or really, any encrypted DNS transport) > and captive portals. While this would accordingly have been best placed > in something generic to DNS privacy mechanisms, such as RFC 9076 or RFC > 8932, I think there might still be room to mention it here. I could > attempt to craft some text, if there is interest. > > I made a pull request with some editorial suggestions at > https://github.com/huitema/dnsoquic/pull/154 > > Section 1 > > The specific non-goals of this document are: > [...] > 2. No attempt to support server-initiated transactions, which are > used only in DNS Stateful Operations (DSO) [RFC8490]. > > RFC 8490 is a proposed standard, so excluding it maybe is a bit in > conflict with claiming that this is a "general-purpose transport for DNS", > absent some other argument that DSO is a special-purpose tool. > > Section 5.1.2 > > DoQ connections MUST NOT use UDP port 53. This recommendation > against use of port 53 for DoQ is to avoid confusion between DoQ and > the use of DNS over UDP [RFC1035]. > > Just to clarify: this prohibition is intended to apply even if there would > otherwise be mutual agreement to use port 53? > > Section 5.2 > > DNS traffic follows a simple pattern in which the client sends a > query, and the server provides one or more responses (multiple > responses can occur in zone transfers). > > Is this true even for DSO server-initiated transactions? > > The client MUST select the next available client-initiated > bidirectional stream for each subsequent query on a QUIC connection, > in conformance with the QUIC transport specification [RFC9000]. > > Just to note: RFC 9000 does not require the client to *use* the "next > available" stream, instead saying that "a stream ID that is used out of > order results in all streams of that type with lower- numbered stream IDs > also being opened". So this "MUST select the next available" is a new > requirement for DoQ, and it's not entirely clear to me that it's required > for interop (though it is more efficient than any alternatives). > > Section 5.2.1 > > This has implications for proxying DoQ message to and from other > transports. For example, proxies may have to manage the fact that > DoQ can support a larger number of outstanding queries on a single > connection than e.g., DNS over TCP because DoQ is not limited by the > Message ID space. This issue already exists for DoH, where a Message > ID of 0 is recommended. > > I'm not sure how often this motivating text is relevant. The ID field > seems to be 16 bits, thus enabling 65k outstanding queries on a single > connection -- how often is there a need to have that many queries > outstanding at once? It looks like the motivation presented in RFC 8484 > for setting the ID to zero is to improve caching, as otherwise queries > identical at the DNS level would be cached as separate requests by HTTP. > I agree, of course, that the ID field is redundant with the QUIC stream ID > and that it should be set to zero, I am just not sure if the number of > outstanding queries is a relevant motivation for doing so. > > (It also looks like RFC 8484 refers to this value as the "DNS ID" rather than > "Message ID". I guess our options for consistent terminology are somewhat > limited, though.) > > Section 5.3 > > The following error codes are defined for use when abruptly > terminating streams, aborting reading of streams, or immediately > closing connections: > > Should we say that these are what QUIC calls "application error code"s? > (Subsequent occurrences of the phrase "error code" might be modified to > "application error code" as well.) > > Section 5.3.2 > > set to DOQ_INTERNAL_ERROR. [...] > > Is there any further guidance to give on when a DNS SERVFAIL response vs > QUIC RESET_STREAM is preferred (or is the guidance really always to issue > RESET_STREAM)? > > Section 5.3.3 > > It is noted that the restrictions on use of the above EDNS(0) options > has implications for proxying message from TCP/DoT/DoH over DoQ. > > Was it already rejeted to spend a sentence mentioning that such proxying > would involve translating the messages per the needs of the different > protocols on the different connections? > > Section 5.5 > > Servers MUST NOT execute non replayable transactions received in > 0-RTT data. Servers MUST adopt one of the following behaviors: > > I think we should clarify whether "execute" means "take any action in > response to" or just "send a response message for". (I think it needs to > be the former.) > > Section 6.4 > > Implementations MUST protect against the traffic analysis attacks > described in Section 9.5 by the judicious injection of padding. This > > I think this is already overtaken by events, but a MUST-level requirement > seems overbearing here. My understanding is that providing complete > protection against these types of attack is still an open research > question.... > > could be done either by padding individual DNS messages using the > EDNS(0) Padding Option [RFC7830] or by padding QUIC packets (see > Section 8.6 of [RFC9000], the QUIC transport specification. > > There is no Section 8.6 in RFC 9000. > > Section 6.5.2 > > Clients that want to maintain long duration DoQ connections SHOULD > use the idle timeout mechanisms defined in Section 10.1 of [RFC9000], > the QUIC transport specification. Clients and servers MUST NOT send > the edns-tcp-keepalive EDNS(0) Option [RFC7828] in any messages sent > on a DoQ connection (because it is specific to the use of TCP/TLS as > a transport). > > Should we make some statement (analogous to what RFC 7828 does) that if > such an option is received it MUST be ignored? In the absence of such > guidance I can imagine implementors feeling a need to enforce the "MUST > NOT send" on the receiving end. > > Section 6.7 > > [RFC9103] specifies zone transfer over TLS (XoT) and includes updates > to [RFC1995] (IXFR), [RFC5936] (AXFR) and [RFC7766]. [...] > > I note that there is currently no "Updates:" header to indicate this > relationship. > > * DoQ implementations SHOULD > > - use the same QUIC connection for both AXFR and IXFR requests to > the same primary > > - pipeline such requests (if they pipeline XFR requests in > general) and MAY intermingle them > > - send the response(s) for each request as soon as they are > available i.e. responses MAY be sent intermingled > > Given the "SHOULD use the same QUIC connection", what does MAY-level > guidance to "intermingle such requests" mean, in a QUIC context? Each DoQ > request is on a separate QUIC stream, so I do not see any opportunity for > intermingling other than by virtue of being in the same QUIC connection, > which is already a SHOULD. This is in contrast to a TCP or TLS situation, > where there is only a single data stream and intermingling has some > natural meaning (or meanings, for the response case specifically, where it > might apply to overall responses (composed of multiple response messages) > or individual response messages). > > Section 8 > > The discussion in §6.5.2 about resource management could be security > relevant at times, if we wanted to backreference it. > > The security considerations of DoQ should be comparable to those of > DoT [RFC7858]. DoT as specified in [RFC7858] only addresses the stub > > The security considerations section of RFC 7858 includes a MUST-level > requirement to adhere to the recommendations of BCP 195. Does such a > MUST-level requirement apply to DoQ as well? (I note that BCP 195 is > currently listed as only an informative reference, which would need to > change if a MUST-level requirement was added.) > > to recursive resolver scenario, but the considerations about person- > in-the-middle attacks, middleboxes and caching of data from clear > text connections also apply for DoQ to the resolver to authoritative > server scenario. [...] > > RFC 7858 also lists a fourth consideration, traffic analysis or > side-channel leaks. Do we want to forward-reference §9.5 for completeness > (or even take the secdir reviewer's suggestion of coalescing the privacy > considerations into the security considerations section as confidentiality > considerations)? > > Section 9.1 > > The prevention on allowing replayable transactions in 0-RTT data > expressed in Section 5.5 blocks the most obvious risks of replay > > Is the parity of negations correct here ("prevention on allowing")? I see > §5.5 prohibiting execution of non-replayable transactions in 0-RTT data, > i.e., allowing replayable ones. > > Section 10.4 > > Provisional reservations share the range of values larger than 0x3f > with some permanent registrations. This is by design, to enable > conversion of provisional registrations into permanent registrations > without requiring changes in deployed systems. (This design is > aligned with the principles set in Section 22 of [RFC9000].) > > Do we want to specifically call out the guidance on selecting specific > codepoints from §22.1.2 of RFC 9000? (Or is it seen as not applicable > here?) > > Section 12.1 > > We currently only specifically reference RFC 6891 in one place, to mention > that its provision for specifying maximum UDP message size is not relevant > for DoQ. However, since we do define and require (in some cases) use of a > new "Too Early" EDNS(0) error code, it seems that the solution should be > to reference it from more places, rather than to demote it to an > informative reference. > > Similarly, we only reference RFC 8914 in the IANA considerations where we > allocate the codepoint, and would likely benefit from sprinkling an > additional reference or two in the main body of the text. > > RFC 7828, on the other hand, seems to only be mentioned to say that you > MUST NOT use it, which would probably be fine as an informative reference. > > RFC 7873 is referenced for "similar to the DNS Cookies mechanism", which > also sounds solely informative. > > [I-D.ietf-dnsop-rfc8499bis] > Hoffman, P. and K. Fujiwara, "DNS Terminology", Work in > Progress, Internet-Draft, draft-ietf-dnsop-rfc8499bis-03, > > It's kind of surprising to see DoQ electing to take a normative dependency > on this draft that is not even in WGLC yet. Wouldn't that risk incurring > substantial (unbounded) delays? > > Section 12.2 > > A SHOULD-level requirement to implement the anti-replay mechanisms from > RFC 8446 seems to promote it to normative status, per > https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/ > > > > _______________________________________________ > dns-privacy mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/dns-privacy _______________________________________________ dns-privacy mailing list [email protected] https://www.ietf.org/mailman/listinfo/dns-privacy
