DS Algorithms for Securing NS and Glue
draft-dickson-dnsop-ds-hack-00

DNSOP Working Group                                          . B Dickson
Internet-Draft                                                   GoDaddy
Intended status: Informational                            11 August 2021
Expires: 12 February 2022

                 DS Algorithms for Securing NS and Glue
                     draft-dickson-dnsop-ds-hack-00

Abstract

   This Internet Draft proposes a mechanism to encode relevant data for
   NS records (and optionally A and AAAA records) on the parental side
   of a zone cut, by encoding them in new DS algorithms.

   Since DS records are signed by the parent, this creates a method for
   validation of the otherwise unsigned delegation and glue records.

   This is beneficial if the name server _names_ are in a DNSSEC signed
   zone.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   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 https://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 12 February 2022.

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   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   Please review these documents carefully, as they describe your rights
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   extracted from this document must include Simplified BSD License text
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   3
   3.  Background  . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  New DNSKEY Algorithms . . . . . . . . . . . . . . . . . . . .   3
     4.1.  Algorithm {TBD1}  . . . . . . . . . . . . . . . . . . . .   3
       4.1.1.  Example . . . . . . . . . . . . . . . . . . . . . . .   4
     4.2.  Algorithm {TBD2}  . . . . . . . . . . . . . . . . . . . .   4
       4.2.1.  Example . . . . . . . . . . . . . . . . . . . . . . .   5
     4.3.  Algorithm {TBD3}  . . . . . . . . . . . . . . . . . . . .   5
       4.3.1.  Example . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Validation Using These DS Records . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   There are new privacy goals and DNS server capability discovery
   goals, which cannot be met without the ability to validate the name
   of the name servers for a given domain at the delegation point.

   Specifically, a query for NS records over an unprotected transport
   path returns results which do not have protection from tampering by
   an active on-path attacker, or against successful cache poisoning
   attackes.

   This is true regardless of the DNSSEC status of the domain containing
   the authoritative information for the name servers for the queried
   domain.

   For example, querying for the NS records for "example.com", at the
   name servers for the "com" TLD, where the published com zone has
   "example.com NS ns1.example.net", is not protected against MITM
   attacks, even if the domain "example.net" (the domain serving records
   for "ns1.example.net") is DNSSEC signed.

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   More infomation can be found in [I-D.nottingham-for-the-users].  (An
   exmple of an informative reference to a draft in the middle of text.
   Note that referencing an Internet draft involves replacing "draft-"
   in the name with "I-D.")

2.  Conventions and Definitions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Background

   The methods developed for adding security to the Domain Name System,
   collectively refered to as DNSSEC, had as a primary requirement that
   they be backward compatible.  The original specifications for DNS
   used the same Resourc Record Type (RRTYPE) on both the parent and
   child side of a zone cut (the NS record).  The main goal of DNSSEC
   was to ensure data integrity by using cryptographic signatures.
   However, owing to this overlap in the NS record type where the
   records above and below the zone cut have the same owner name created
   an inherent conflict, as only the child zone is authoritative for
   these records.

   The result is that the parental side of the zone cut has records
   needed for DNS resolution which are not signed and not validatable.

   This has no impact on DNS zones which are fully DNSSEC signed
   (anchored at the IANA DNS Trust Anchor), but does impact unsigned
   zones regardless of where the transition from secure to insecure
   occurs.

4.  New DNSKEY Algorithms

   These new DNSKEY algorithms conform to the structure requirements
   from [RFC4034], but are not themselves used as actual DNSKEY
   algorithms.  They are assigned values from the DNSKEY algorithm
   table.  No DNSKEY records are published with these algorithms.

   They are used only as the input to the corresponding DS hashes
   published in the parent zone.

4.1.  Algorithm {TBD1}

   This algorithm is used to validate the NS records of the delegation
   for the owner name.

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   The NS records are canonicalized and sorted according to the DNSSEC
   signing process [RFC4034] section 6, including removing any label
   compression, and normalizing the character cases to lower case.  The
   RDATA fields of the records are concatenated, and the result is
   hashed using the selected digest algorithm(s), e.g.  SHA2-256 for DS
   digest algorithm 1.

4.1.1.  Example

   Consider the delegation in the COM zone: example.com NS
   ns1.example.net example.com NS ns2.example.net

   These two records have RDATA, which after canonicalization and
   sorting, would be ns1.example.net ns2.example.net

   The input to the digest is the concatenation of those values in wire
   format.  For example, if the NS set's RDATA are "ns1.example.net" and
   "ns2.example.net", the wire format would be

   0x03
   ns1
   0x07
   example
   0x03
   net
   0x00
   0x03
   ns2
   0x07
   example
   0x03
   net
   0x00

   The Key Tag is calculated per [RFC4034] using this value as the
   RDATA.

   The resulting DS record is

   example.com DS KeyTag=0 Algorithm={TBD1} DigestType=2 \
   Digest=sha2-256()

4.2.  Algorithm {TBD2}

   This algorithm is used to validate the glue A records required as
   glue for the delegation NS set associated with the owner name.

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   The glue A records are canonicalized and sorted according to the
   DNSSEC signing process [RFC4034], including removing any label
   compression, and normalizing the character cases.  The entirety of
   the records are concatenated, and the result is hashed using the
   selected hash type(s), e.g.  SHA2-256 for DS type 2.

4.2.1.  Example

   For example, if the original "glue" (unsigned) A records are:

   ns1.example.net IN 3600 A standard-example-ip-1
   ns2.example.net IN 3600 A standard-example-ip-2

   There would be one DS record for each of the glue "A" records, with
   the canonicalized wire format of the entire record provided as input
   to the hash function.

   FIXME replace 0xfffffffx with real example IP addresses
   (per IANA table of example IPs)
   First A record's DS record:
   wire_format(ns1.example.net) 0x01 0x01 3600 0xfffffff0
   Second A record's DS record:
   wire_format(ns2.example.net) 0x01 0x01 3600 0xfffffff1

   Then the resulting DS record is

   FIXME - who is the right owner to use here?
   (The glue owner name, or the zone owner name (bailiwick only)?)
   example.net DS KeyTag=0 Algorithm={TBD2} DigestType=2 \
   Digest=sha2-256()
   example.net DS KeyTag=0 Algorithm={TBD2} DigestType=2 \
   Digest=sha2-256()

4.3.  Algorithm {TBD3}

   This algorithm is used to validate the glue AAAA records required as
   glue for the delegation NS set associated with the owner name.

   The glue AAAA records are canonicalized and sorted according to the
   DNSSEC signing process [RFC4034], including removing any label
   compression, and normalizing the character cases.  The entirety of
   the records are concatenated, and the result is hashed using the
   selected hash type(s), e.g.  SHA2-256 for DS type 2.

4.3.1.  Example

   For example, if the original "glue" (unsigned) AAAA records are:

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   ns1.example.net IN 3600 AAAA standard-example-ip6-1
   ns2.example.net IN 3600 AAAA standard-example-ip6-2

   There would be one DS record for each of the glue "A" records, with
   the canonicalized wire format of the entire record provided as input
   to the hash function.

   FIXME replace 0xfffffffx with real example IP addresses
   (per IANA table of example IPs)
   First A record's DS record:
   wire_format(ns1.example.net) 0x01 0xXX 3600 0x32-hex-digits
   Second A record's DS record:
   wire_format(ns2.example.net) 0x01 0xXX 3600 0x32-hex-digits

   Then the resulting DS record is

   FIXME - who is the right owner to use here?
   (The glue owner name, or the zone owner name (bailiwick only)?)
   example.net DS KeyTag=0 Algorithm={TBD2} DigestType=2 \
   Digest=sha2-256()
   example.net DS KeyTag=0 Algorithm={TBD2} DigestType=2 \
   Digest=sha2-256()

5.  Validation Using These DS Records

   These new DS records are used to validate corresponding delegation
   records and glue, as follows: - NS records are validated using {TBD1}
   - Glue A records (if present) are validated using {TBD2} - Glue AAAA
   records (if present) are validated using {TBD3}

   The same method used for constructing the DS records, is used to
   validate their contents.  The algorithm is replicated with the
   corresponding inputs, and the hash compared to the published DS
   record(s).

6.  Security Considerations

   As outlined above, there could be security issues in various use
   cases.

7.  IANA Considerations

   This document has no IANA actions.  (Well, actually, TBD1, TBD2, and
   TBD3 need to be assigned from the DNSSEC DNSKEY Algorithm Table.)

8.  References

8.1.  Normative References

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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC4034]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Resource Records for the DNS Security Extensions",
              RFC 4034, DOI 10.17487/RFC4034, March 2005,
              <https://www.rfc-editor.org/info/rfc4034>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

8.2.  Informative References

   [I-D.nottingham-for-the-users]
              Nottingham, M., "The Internet is for End Users", Work in
              Progress, Internet-Draft, draft-nottingham-for-the-users-
              09, 22 July 2019, <https://www.ietf.org/archive/id/draft-
              nottingham-for-the-users-09.txt>.

Acknowledgments

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   Thanks to YOUR NAME HERE for contributions, reviews, etc.

Author's Address

   Brian Dickson
   GoDaddy

   Email: brian.peter.dickson@gmail.com

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