--- 1/draft-ietf-dnsop-extended-error-10.txt 2019-09-30 17:13:12.960147571 -0700 +++ 2/draft-ietf-dnsop-extended-error-11.txt 2019-09-30 17:13:12.996148481 -0700 @@ -1,25 +1,25 @@ Network Working Group W. Kumari Internet-Draft Google Intended status: Standards Track E. Hunt -Expires: March 30, 2020 ISC +Expires: April 2, 2020 ISC R. Arends ICANN W. Hardaker USC/ISI D. Lawrence Oracle + Dyn - September 27, 2019 + September 30, 2019 Extended DNS Errors - draft-ietf-dnsop-extended-error-10 + draft-ietf-dnsop-extended-error-11 Abstract This document defines an extensible method to return additional information about the cause of DNS errors. Though created primarily to extend SERVFAIL to provide additional information about the cause of DNS and DNSSEC failures, the Extended DNS Errors option defined in this document allows all response types to contain extended error information. Extended DNS Error information does not change the processing of RCODEs. @@ -32,21 +32,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on March 30, 2020. + This Internet-Draft will expire on April 2, 2020. Copyright Notice Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -70,29 +70,29 @@ 3.4. Extended DNS Error Code 3 - Stale Answer . . . . . . . . 5 3.5. Extended DNS Error Code 4 - Forged Answer . . . . . . . . 5 3.6. Extended DNS Error Code 5 - DNSSEC Indeterminate . . . . 6 3.7. Extended DNS Error Code 6 - DNSSEC Bogus . . . . . . . . 6 3.8. Extended DNS Error Code 7 - Signature Expired . . . . . . 6 3.9. Extended DNS Error Code 8 - Signature Not Yet Valid . . . 6 3.10. Extended DNS Error Code 9 - DNSKEY Missing . . . . . . . 6 3.11. Extended DNS Error Code 10 - RRSIGs Missing . . . . . . . 6 3.12. Extended DNS Error Code 11 - No Zone Key Bit Set . . . . 6 3.13. Extended DNS Error Code 12 - NSEC Missing . . . . . . . . 6 - 3.14. Extended DNS Error Code 13 - Cached Error . . . . . . . . 6 + 3.14. Extended DNS Error Code 13 - Cached Error . . . . . . . . 7 3.15. Extended DNS Error Code 14 - Not Ready . . . . . . . . . 7 3.16. Extended DNS Error Code 15 - Blocked . . . . . . . . . . 7 3.17. Extended DNS Error Code 16 - Censored . . . . . . . . . . 7 3.18. Extended DNS Error Code 17 - Filtered . . . . . . . . . . 7 - 3.19. Extended DNS Error Code 17 - Prohibited . . . . . . . . . 7 + 3.19. Extended DNS Error Code 18 - Prohibited . . . . . . . . . 7 3.20. Extended DNS Error Code 19 - Stale NXDOMAIN Answer . . . 7 - 3.21. Extended DNS Error Code 20 - Not Authoritative . . . . . 7 - 3.22. Extended DNS Error Code 21 - Deprecated . . . . . . . . . 8 + 3.21. Extended DNS Error Code 20 - Not Authoritative . . . . . 8 + 3.22. Extended DNS Error Code 21 - Not Supported . . . . . . . 8 3.23. Extended DNS Error Code 22 - No Reachable Authority . . . 8 3.24. Extended DNS Error Code 23 - Network Error . . . . . . . 8 3.25. Extended DNS Error Code 24 - Invalid Data . . . . . . . . 8 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 4.1. A New Extended DNS Error Code EDNS Option . . . . . . . . 8 4.2. New Registry Table for Extended DNS Error Codes . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 7.1. Normative References . . . . . . . . . . . . . . . . . . 12 @@ -103,21 +103,22 @@ There are many reasons that a DNS query may fail, some of them transient, some permanent; some can be resolved by querying another server, some are likely best handled by stopping resolution. Unfortunately, the error signals that a DNS server can return are very limited, and are not very expressive. This means that applications and resolvers often have to "guess" at what the issue is - e.g. was the answer marked REFUSED because of a lame delegation, or because the nameserver is still starting up and loading zones? Is a SERVFAIL a DNSSEC validation issue, or is the nameserver experiencing - some other failure? + some other failure? What error messages should be presented to the + user or logged under these conditions? A good example of issues that would benefit by additional error information are errors caused by DNSSEC validation issues. When a stub resolver queries a name which is DNSSEC bogus (using a validating resolver), the stub resolver receives only a SERVFAIL in response. Unfortunately, the SERVFAIL Response Code (RCODE) is used to signal many sorts of DNS errors, and so the stub resolvers only option is to ask the next configured DNS resolver. The result of trying the next resolver is one of two outcomes: either the next resolver also validates, and a SERVFAIL is returned again or the next @@ -135,23 +136,23 @@ and thus different systems (stub resolvers, recursive resolvers, and authoritative resolvers) might receive and use them. This document does not allow or prohibit any particular extended error codes and information to be matched with any particular RCODEs. Some combinations of extended error codes and RCODEs may seem nonsensical (such as resolver-specific extended error codes in responses from authoritative servers), so systems interpreting the extended error codes MUST NOT assume that a combination will make sense. Receivers MUST be able to accept EDE codes and EXTRA-TEXT in - all messages, including those with a NOERROR RCODE. Receivers MUST - NOT change the processing of RCODEs in messages based on extended - error codes. + all messages, including those with a NOERROR RCODE. Applications + MUST continue to follow requirements from applicable specs on how to + process RCODEs no matter what EDE values is also received 1.1. Requirements notation The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 2. Extended Error EDNS0 option format This draft uses an EDNS0 ([RFC2671]) option to include Extended DNS @@ -165,26 +166,27 @@ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ 2: | OPTION-LENGTH | +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ 4: | INFO-CODE | +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ 6: / EXTRA-TEXT ... / +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ Field definition details: - o OPTION-CODE, 2 octets (defined in [RFC6891]]), for EDE is TBD. - [RFC Editor: change TBD to the proper code once assigned by IANA.] - o OPTION-LENGTH, 2 octets ((defined in [RFC6891]]) contains the - length of the payload (everything after OPTION-LENGTH) in octets - and should be 4 plus the length of the EXTRA-TEXT section (which - may be a zero-length string). + o OPTION-CODE, 2-octets/16-bits (defined in [RFC6891]]), for EDE is + TBD. [RFC Editor: change TBD to the proper code once assigned by + IANA.] + o OPTION-LENGTH, 2-octets/16-bits ((defined in [RFC6891]]) contains + the length of the payload (everything after OPTION-LENGTH) in + octets and should be 4 plus the length of the EXTRA-TEXT section + (which may be a zero-length string). o INFO-CODE, 16-bits, which is the principal contribution of this document. This 16-bit value, encoded in network (MSB) byte order, provides the additional context for the RESPONSE-CODE of the DNS message. The INFO-CODE serves as an index into the "Extended DNS Errors" registry Section 4.1. o EXTRA-TEXT, a variable length, UTF-8 encoded, text field that may hold additional textual information. Note: EXTRA-TEXT may be zero octets in length, indicating there is no EXTRA-TEXT included. Care should be taken not to leak private information that an observer would not otherwise have access to, such as account @@ -243,27 +245,27 @@ The resolver attempted to perform DNSSEC validation, but validation ended in the Indeterminate state [RFC4035]. 3.7. Extended DNS Error Code 6 - DNSSEC Bogus The resolver attempted to perform DNSSEC validation, but validation ended in the Bogus state. 3.8. Extended DNS Error Code 7 - Signature Expired - The resolver attempted to perform DNSSEC validation, but all - signatures in an RRset in the validation chain were expired. + The resolver attempted to perform DNSSEC validation, but no + signatures are presently valid and some (often all) are expired. 3.9. Extended DNS Error Code 8 - Signature Not Yet Valid - The resolver attempted to perform DNSSEC validation, but all the - signatures received were not yet valid. + The resolver attempted to perform DNSSEC validation, but but no + signatures are presently valid and at least some are not yet valid. 3.10. Extended DNS Error Code 9 - DNSKEY Missing A DS record existed at a parent, but no supported matching DNSKEY record could be found for the child. 3.11. Extended DNS Error Code 10 - RRSIGs Missing The resolver attempted to perform DNSSEC validation, but no RRSIGs could be found for at least one RRset where RRSIGs were expected. @@ -274,21 +276,21 @@ Bit was set in a DNSKEY. 3.13. Extended DNS Error Code 12 - NSEC Missing The resolver attempted to perform DNSSEC validation, but the requested data was missing and a covering NSEC or NSEC3 was not provided. 3.14. Extended DNS Error Code 13 - Cached Error - The resolver has Cached SERVFAIL for this query. + The resolver is returning the SERVFAIL RCODE from its cache. 3.15. Extended DNS Error Code 14 - Not Ready The server is unable to answer the query as it is not fully functional (yet). 3.16. Extended DNS Error Code 15 - Blocked The server is unable to respond to the request because the domain is blacklisted due to an internal security policy imposed by the @@ -300,45 +302,45 @@ blacklisted by a security policy imposed upon the server being talked to by an external requirement. Note that how the imposed policy is applied is irrelevant (in-band DNS filtering, court order, etc). 3.18. Extended DNS Error Code 17 - Filtered The server is unable to respond to the request because the domain is blacklisted as requested by the client. Functionally, this amounts to "you requested that we filter domains like this one." -3.19. Extended DNS Error Code 17 - Prohibited +3.19. Extended DNS Error Code 18 - Prohibited An authoritative or recursive resolver that receives a query from an "unauthorized" client can annotate its REFUSED message with this code. Examples of "unauthorized" clients are recursive queries from IP addresses outside the network, blacklisted IP addresses, local policy, etc. 3.20. Extended DNS Error Code 19 - Stale NXDOMAIN Answer The resolver was unable to resolve an answer within its configured time limits and decided to answer with a previously cached NXDOMAIN - answer instead of answering with an error. This is typically caused - by problems communicating with an authoritative server, possibly as - result of a DoS attack against another network. + answer instead of answering with an error. This is may be caused, + for example, by problems communicating with an authoritative server, + possibly as result of a DoS attack against another network. 3.21. Extended DNS Error Code 20 - Not Authoritative An authoritative server that receives a query (with the RD bit clear, or when not configured for recursion) for a domain for which it is not authoritative SHOULD include this EDE code in the REFUSED response. A resolver that receives a query (with the RD bit clear) SHOULD include this EDE code in the REFUSED response. -3.22. Extended DNS Error Code 21 - Deprecated +3.22. Extended DNS Error Code 21 - Not Supported The requested operation or query is not supported as its use has been deprecated. 3.23. Extended DNS Error Code 22 - No Reachable Authority The resolver could not reach any of the authoritative name servers (or they refused to reply). 3.24. Extended DNS Error Code 23 - Network Error @@ -459,21 +461,21 @@ INFO-CODE: 19 Purpose: Stale NXDomain Answer Reference: Section 3.20 INFO-CODE: 20 Purpose: Not Authoritative Reference: Section 3.21 INFO-CODE: 21 - Purpose: Deprecated + Purpose: Not Supported Reference: Section 3.22 INFO-CODE: 22 Purpose: No Reachable Authority Reference: Section 3.23 INFO-CODE: 23 Purpose: Network Error Reference: Section 3.24 @@ -496,30 +498,30 @@ would not trust any unauthenticated information, but until we live in an era where all DNS answers are authenticated via DNSSEC or other mechanisms [RFC2845] [RFC8094], there are some tradeoffs. As an example, an attacker who is able to insert the DNSSEC Bogus Extended Error into a packet could instead simply reply with a fictitious address (A or AAAA) record. Note that DNS Response Codes also contain no authentication and can be just as easily manipulated. 6. Acknowledgements - The authors wish to thank Joe Abley, Mark Andrews, Vittorio Bertola, - Stephane Bortzmeyer, Vladimir Cunat, Ralph Dolmans, Peter DeVries, - Peter van Dijk, Mats Dufberg, Donald Eastlake, Bob Harold, Paul - Hoffman, Geoff Huston, Shane Kerr, Edward Lewis, Carlos M. Martinez, - George Michelson, Eric Orth, Michael Sheldon, Puneet Sood, Petr - Spacek, Ondrej Sury, John Todd, Loganaden Velvindron, and Paul Vixie. - They also vaguely remember discussing this with a number of people - over the years, but have forgotten who all they were -- if you were - one of them, and are not listed, please let us know and we'll - acknowledge you. + The authors wish to thank Joe Abley, Mark Andrews, Tim April, + Vittorio Bertola, Stephane Bortzmeyer, Vladimir Cunat, Ralph Dolmans, + Peter DeVries, Peter van Dijk, Mats Dufberg, Donald Eastlake, Bob + Harold, Paul Hoffman, Geoff Huston, Shane Kerr, Edward Lewis, Carlos + M. Martinez, George Michelson, Eric Orth, Michael Sheldon, Puneet + Sood, Petr Spacek, Ondrej Sury, John Todd, Loganaden Velvindron, and + Paul Vixie. They also vaguely remember discussing this with a number + of people over the years, but have forgotten who all they were -- if + you were one of them, and are not listed, please let us know and + we'll acknowledge you. One author also wants to thank the band "Infected Mushroom" for providing a good background soundtrack (and to see if he can get away with this in an RFC!) Another author would like to thank the band "Mushroom Infectors". This was funny at the time we wrote it, but we cannot remember why... 7. References 7.1. Normative References