DNS-over-TLS for insecure delegations
draft-bretelle-dprive-dot-for-insecure-delegations-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Expired".
|
|
|---|---|---|---|
| Author | Manu Bretelle | ||
| Last updated | 2018-09-27 | ||
| RFC stream | (None) | ||
| Formats | |||
| Additional resources | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-bretelle-dprive-dot-for-insecure-delegations-00
Network Working Group M. Bretelle
Internet-Draft Facebook
Intended status: Standards Track September 27, 2018
Expires: March 31, 2019
DNS-over-TLS for insecure delegations
draft-bretelle-dprive-dot-for-insecure-delegations-00
Abstract
This document describes an alternate mechanism to DANE ([RFC6698]) in
order to authenticate a DNS-over-TLS (DoT [RFC7858]) authoritative
server by not making DNSSEC a hard requirement, making DoT server
authentication available for insecure delegations.
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 March 31, 2019.
Copyright Notice
Copyright (c) 2018 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
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Bretelle Expires March 31, 2019 [Page 1]
Internet-Draft dot-for-insecure-delegations September 2018
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Authenticating an insecure delegation . . . . . . . . . . . . 3
3.1. Public Key Infranstructure (PKIX) . . . . . . . . . . . . 3
3.2. Simple Public-Key Infrastructure (SPKI) . . . . . . . . . 3
3.3. Authenticating from the parent . . . . . . . . . . . . . 4
3.3.1. Example . . . . . . . . . . . . . . . . . . . . . . . 4
4. DSPKI Resource Record . . . . . . . . . . . . . . . . . . . . 5
4.1. DSPKI RDATA Format . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Normative References . . . . . . . . . . . . . . . . . . . . 5
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
This document describes an alternate mechanism to [RFC6698] as
described in [I-D.bortzmeyer-dprive-resolver-to-auth] Section 2
extending the authentication of DoT [RFC7858] to insecure delegations
and therefore enabling the onboarding of DoT authoritative servers
without the requirement for the authorities to support DNSSEC
([RFC4033], [RFC4034], and [RFC4035]). To do so, this document
introduce the Delegation SPKI (DSPKI) resource record, its purpose,
usage and format.
2. Terminology
A server that supports DNS-over-TLS is called a "DoT server" to
differentiate it from a "DNS Server" (one that provides DNS service
over any other protocol), likewise, a client that supports this
protocol is called a "DoT client"
A secure delegation ([RFC4956] Section 2) is a signed name containing
a delegation (NS RRset), and a signed DS RRset, signifying a
delegation to a signed zone.
An insecure delegation ([RFC4956] Section 2) is a signed name
containing a delegation (NS RRset), but lacking a DS RRset,
signifying a delegation to an unsigned subzone.
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.
Bretelle Expires March 31, 2019 [Page 2]
Internet-Draft dot-for-insecure-delegations September 2018
3. Authenticating an insecure delegation
To authenticate a DoT server of a secure delegation, it is possible
to use the TLSA resource record [RFC6698] of the nameserver as
decribed in [I-D.bortzmeyer-dprive-resolver-to-auth] Section 2, while
this method is valid, the absence of support of DNSSEC for such
delegations precludes the onboarding and discovery of nameservers
serving those zones as DoT servers.
Without the use of DNSSEC, a delegation is not able to authenticate
itself as the chain of trust cannot be followed, however other
mechanisms exist to have a server authenticate itself, such as Public
Key Infrastructure (PKIX [RFC6125]) , SPKI, which have their own pros
and cons.
3.1. Public Key Infranstructure (PKIX)
It would be possible to authenticate the nameservers of the insecure
delegation using PKIX, relying on an existing trust model and trust
anchors.
While simple, a single trusted CA that breaks said trust (voluntarily
or involuntarily), can issue certificate for any domains, allowing an
attacker to potentially impersonate both the application and the DoT
server.
Another issue that rises is that the DoT servers may use an identity
which belong to the same origin as application servers, which could
permit personal information (such as cookies) to be leaked to the DoT
servers.
3.2. Simple Public-Key Infrastructure (SPKI)
SPKI on the other hand does not have the same issues than PKIX, the
certificates can be generated by the authority itself, adding a
separation of privileges between the PKIX infrastructure and the DNS
one.
The problem is now on how to advertise/distribute the delegation's
public key.
This is in essence what TLSA records solve, but with the use of
DNSSEC enabled and functional for the queried zone. For insecure
delegations, simply advertising the public key would be subject to
interception and mangling.
Bretelle Expires March 31, 2019 [Page 3]
Internet-Draft dot-for-insecure-delegations September 2018
3.3. Authenticating from the parent
While a delegation is not secured, the DNS core infrastructure
already support DNSSEC, meaning that if the owner of an insecure
delegation could set the public key to authenticate the DoT servers
against, such key could be authenticated using DNSSEC at the parent
level, which would then permit trusting the DoT servers providing
their certificate validates against the ( then validated) public key
provided by the parent.
From this stage, the "formerly" insecure delegation can be
authenticated, and therefore considered secure, allowing delegating
to other zones which can be authenticated by either DNSSEC or TLS.
In order to provide its public key to the DoT clients, an insecure
would set the DSPKI RRset at the parent with the content of its
extracted SPKI, which the parent then sign.
A DoT client which is about to talk with a DoT server can obtain and
validate the DSPKI RRset from the parent and authenticate the DoT
server, without needing the DoT server to serve a secure delegation.
3.3.1. Example
example.com is an insecure delegation from .com which has set the
DSPKI RRset.
A DoT client looking for records under example.com will learn from
.com that example.com is delegated to
example.com 172800 NS ns1.example.com
example.com 172800 NS ns2.example.com
example.com 86400 DSPKI h0KPxSKAPTEGXnvOPPA/5HUJZjHl4Hu9eg/eYMTPJcc=
ns1.example.com 172800 AAAA 2001:db8:abcd:12:1:2:3:4
ns2.example.com 172800 AAAA 2001:db8:abcd:ab:1:2:3:4
with the accompanying signature.
The DSPKI RRset signals that the nameservers are able to support DNS-
over-TLS and the DoT client can authenticate them using the provided
public key,
If subzone.example.com is a delegation from example.com, example.com
can provide the DSPKI RRSet of the delegation. While example.com is
not a secured delegation, because it has been authenticated using
TLS, it is also able to be part of the chain of trust and provide
either a DS or DSPKI RRset for subzone.example.com
Bretelle Expires March 31, 2019 [Page 4]
Internet-Draft dot-for-insecure-delegations September 2018
4. DSPKI Resource Record
There may be 0 or more DSPKI served by the parent of the delegation.
0 would mean that DSPKI is not supported, therefore the DoT client
could try other alternatives. 1 or multiple public keys can be
distributed to let the DoT client validate multiple public keys,
which can be useful while doing certificate rotation or when willing
to provide different secret keys to different providers that may
serve the delegated zone.
4.1. DSPKI RDATA Format
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
/ PUBKEY /
/ /
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
Where PUBKEY: A base64 encoded string of the sha256sum of the public
key, as generated by: ~~~~ openssl x509 -in cert.pem -pubkey -noout |
openssl pkey -pubin -outform der | \ openssl dgst -sha256 -binary |
openssl enc -base64 ~~~~
*FIXME*: consider * format that can evolve over time, e.g 1 byte
specifying hashing algorithm. * no need for base64, raw bytes are
fine. * alternate URI to support DoT (host, port, spki), DoH (host,
port, URL template), DNS-over-QUIC... would rather be an ALTNS type
of record * CDSPKI a la CDS, CDNSKEY
5. Security Considerations
TODO Security
6. IANA Considerations
TODO: This document requires IANA actions (new RR type).
7. Normative References
[I-D.bortzmeyer-dprive-resolver-to-auth]
Bortzmeyer, S., "Encryption and authentication of the DNS
resolver-to-authoritative communication", draft-
bortzmeyer-dprive-resolver-to-auth-01 (work in progress),
March 2018.
[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>.
Bretelle Expires March 31, 2019 [Page 5]
Internet-Draft dot-for-insecure-delegations September 2018
[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "DNS Security Introduction and Requirements",
RFC 4033, DOI 10.17487/RFC4033, March 2005,
<https://www.rfc-editor.org/info/rfc4033>.
[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>.
[RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Protocol Modifications for the DNS Security
Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005,
<https://www.rfc-editor.org/info/rfc4035>.
[RFC4956] Arends, R., Kosters, M., and D. Blacka, "DNS Security
(DNSSEC) Opt-In", RFC 4956, DOI 10.17487/RFC4956, July
2007, <https://www.rfc-editor.org/info/rfc4956>.
[RFC6125] Saint-Andre, P. and J. Hodges, "Representation and
Verification of Domain-Based Application Service Identity
within Internet Public Key Infrastructure Using X.509
(PKIX) Certificates in the Context of Transport Layer
Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March
2011, <https://www.rfc-editor.org/info/rfc6125>.
[RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
of Named Entities (DANE) Transport Layer Security (TLS)
Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August
2012, <https://www.rfc-editor.org/info/rfc6698>.
[RFC7250] Wouters, P., Ed., Tschofenig, H., Ed., Gilmore, J.,
Weiler, S., and T. Kivinen, "Using Raw Public Keys in
Transport Layer Security (TLS) and Datagram Transport
Layer Security (DTLS)", RFC 7250, DOI 10.17487/RFC7250,
June 2014, <https://www.rfc-editor.org/info/rfc7250>.
[RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D.,
and P. Hoffman, "Specification for DNS over Transport
Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May
2016, <https://www.rfc-editor.org/info/rfc7858>.
[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>.
Bretelle Expires March 31, 2019 [Page 6]
Internet-Draft dot-for-insecure-delegations September 2018
Acknowledgments
TODO acknowledge.
Author's Address
Emmanuel Bretelle
Facebook
Email: chantra@fb.com
Bretelle Expires March 31, 2019 [Page 7]