wdiff rfc7410.original rfc7410.txt

Individual submission
Internet Engineering Task Force (IETF) M. Kucherawy
Request for Comments: 7410
Updates: 7001 (if approved)
Intended status: December 2014
Category: Standards Track
Expires: April 3, 2015
ISSN: 2070-1721

A Property Types Registry for the Authentication-Results Header Field
draft-ietf-appsawg-authres-ptypes-registry-04

Abstract

This document updates RFC7001 RFC 7001 by creating a registry for property
types in the Authentication-Results header field, used in email
authentication work, rather than limiting participants to using the
original, small set of fixed values.

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 an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force
(IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list It represents the consensus of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid the IETF community. It has
received public review and has been approved for a maximum publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.

Information about the current status of six months this document, any errata,
and how to provide feedback on it may be updated, replaced, or obsoleted by other documents obtained 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 April 3, 2015.
http://www.rfc-editor.org/info/rfc7410.

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
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.

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2
2. Updated 'ptype' "ptype" Definition . . . . . . . . . . . . . . . . . . 3 2
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 4
5. Normative References . . . . . . . . . . . . . . . . . . . . . 5
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . . 5 6

1. Introduction

[RFC7001] defines the email Authentication-Results header field that
presents the results of an authentication effort in a machine-
readable format. The header field creates a place to collect the
output from authentication processes that are disjoint from later
processes that might use the output, such as analysis, filtering filtering, or
sorting mechanisms.

The specification in that document enumerated a small set of types of
properties that can be reported using this mechanism. There has
emerged a desire to report types of properties about a message
through this mechanism. Accordingly, this document updates the
specification to allow for additional property types ("ptypes")
beyond the original set, set and creates a registry where new ones can be
listed and their defining documents referenced.

2. Updated 'ptype' "ptype" Definition

Advanced Backus Naur Form (ABNF) is defined in [RFC5234].

The ABNF in Section 2.2 of [RFC7001] is updated as follows:

ptype = Keyword
; indicates whether the property being evaluated was
; a parameter to an [SMTP] command, was a value taken
; from a message header field, was some property of
; the message body, or was some other property evaluated by
; the receiving Message Transfer Agent (MTA)

The ABNF token "Keyword" is defined in Section 4.1.2 of [RFC5321].

Legal values of "ptype" are as defined in the IANA "Email
Authentication Property Types" registry (see Section 3). The initial
values are as follows, matching those defined in [RFC7001]:

body: Indicates information that was extracted from the body of the
message. This might be an arbitrary string of bytes, a hash of a
string of bytes, a Uniform Resource Identifier, or some other
content of interest.

header: Indicates information that was extracted from the header of
the message. This might be the value of a header field or some
portion of a header field.

policy: A local policy mechanism was applied that augments or
overrides the result returned by the authentication mechanism.
See Section 2.3 of [RFC7001].

smtp: Indicates information that was extracted from an SMTP command
that was used to relay the message.

When a consumer of this header field encounters a ptype "ptype" that it
does not understand, it ignores the result reported with that ptype.
"ptype".

3. IANA Considerations

IANA is requested to create has created the Email "Email Authentication Property Types
sub-registry Types" sub-
registry within the existing Email "Email Authentication Parameters Parameters"
registry. Entries in this registry are subject to the Expert Review
rules as described in [RFC5226]. Each entry in the registry requires
the following values:

o The "ptype" token to be registered, which must fit within the ABNF
described in Section 2.

o A brief description of what sort of information this "ptype" is
meant to cover.

o An optional reference to the defining document. This is
recomended,
recommended, but not required.

The initial entries in this table are as follows, taken from
[RFC7001]:

For new entries, the Designated Expert needs to assure that the
description provided for the new entry adequately describes the
intended use. An example would be helpful to include in the entry's
defining document, if any, although entries in the Email "Email
Authentication Methods Methods" registry or the Email "Email Authentication Result
Names
Names" registry might also serve as examples of intended use.

4. Security Considerations

It is unknown how legacy code, which expects one of a fixed set of
"ptype" tokens, will handle new tokens as they begin to appear.
There are typically two options: prevent delivery of the message, or
ignore those portions of the field that use unknown "ptype" tokens
and allow processing of the message to continue.

The choice comes down to whether the consumer considers it a threat
when there are unknown "ptypes" present. The semantics of the report
are unknown; the report might be indicating the message is authentic,
fraudulent, or that a test failed to complete. The report itself is
not actionable because it cannot be understood, and only its presence
is certain.

Generally, the advice in this situation is to ignore unknown
"ptypes". It is anticipated that a new property type evaluated by
earlier handling agents would also result in the filtering of
messages by those agents until consumers can be updated to interpret
them.

5. Normative References

[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008. 2008, <http://www.rfc-editor.org/info/rfc5226>.

[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008. 2008,
<http://www.rfc-editor.org/info/rfc5234>.

[RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
October 2008. 2008, <http://www.rfc-editor.org/info/rfc5321>.

[RFC7001] Kucherawy, M., "Message Header Field for Indicating
Message Authentication Status", RFC 7001, September 2013. 2013,
<http://www.rfc-editor.org/info/rfc7001>.

Appendix A. Acknowledgements

The author wishes to acknowledge the following for their review and
constructive criticism of this update: Dave Crocker, Tim Draegen,
Scott Kitterman, and Franck Martin.

Author's Address

Murray S. Kucherawy
270 Upland Drive
San Francisco, CA 94127
US
United States

EMail: superuser@gmail.com