User Names for HTTP Resources
draft-vanrein-http-unauth-user-03
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 | Rick van Rein | ||
| Last updated | 2020-01-26 | ||
| RFC stream | (None) | ||
| Formats | |||
| 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-vanrein-http-unauth-user-03
Network Working Group R. Van Rein
Internet-Draft InternetWide.org
Intended status: Standards Track January 26, 2020
Expires: July 29, 2020
User Names for HTTP Resources
draft-vanrein-http-unauth-user-03
Abstract
Most protocols support users under domain names, but HTTP does not.
Usage patterns in the wild do suggest a desire to have this facility.
This specification defines a header for user names, orthogonal to any
authentication or authorisation concerns.
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 July 29, 2020.
Copyright Notice
Copyright (c) 2020 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.
Van Rein Expires July 29, 2020 [Page 1]
Internet-Draft HTTP user@ January 2020
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. The HTTP User Header . . . . . . . . . . . . . . . . . . . . 2
3. Protocol Handling of HTTP User . . . . . . . . . . . . . . . 3
4. Orthogonality of Authentication (Example) . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. Normative References . . . . . . . . . . . . . . . . . . . . 6
Appendix A. HTTP User Environment Variable . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Most protocols support Network Access Identifiers [RFC7542] like
john@example.com to identify users like john under domains such as
example.com. The URI format for HTTP can express [Section 2.7.1 of
[RFC7230]] such authority sections, and many online applications seem
to want to address individual users, but HTTP URIs do not usually
express user names. This specification therefore introduces a header
"User", in close parallel to the "Host" header.
Historically, user names have been coupled to (Basic and Digest)
authentication. This is not generally correct; the user name in the
URI specifies a resource name space, not an (authenticated) client
identity. By using a new header field, this specification allows
authentication to be orthogonal to resource name space selection.
Some user agents have supported (Basic and Digest) authentication
with a "user:password" format in the authority section of URIs. This
has now been deprecated [Section 3.2.1 of [RFC3986]] but the form
with just "user" and no ":password" continues to be acceptable.
Various HTTP clients have different handling for this form, sometimes
flagging it incorrectly as a security hazard, which also motivates a
specification for proper handling.
The purpose of this specification is to define clear meaning for HTTP
URIs with a user name.
2. The HTTP User Header
The "User" header field provides an aspect of the desired resource
name scope. The value is usually taken from the authority section
[Section 3.2 of [RFC3986]] of the target URI and MUST NOT include a
":" colon (U+003a) character.
The User header value holds precisely one value with the following
ABNF grammar:
Van Rein Expires July 29, 2020 [Page 2]
Internet-Draft HTTP user@ January 2020
User = 1*( unreserved / pct-encoded / sub-delims )
The referenced non-terminals are as for URIs [RFC3986] and can be
directly included in the quoted-string form; a plain token cannot
express "(", ")", "=", ";" and "," without escaping [Section 3.2.6 of
[RFC7230]].
3. Protocol Handling of HTTP User
User agents SHOULD render user names in authority sections whenever
they render host names, though it may be helpful if it stands out
graphically [Section 7.6 of [RFC3986]]. User agents SHOULD NOT
remove user names from the target URI. User agents MAY remove the
"@" (U+0040) symbol from a URI when the preceding user name is empty.
User agents MUST reject userinfo sections containing a colon ":"
(U+003a) or URI syntax errors and MAY warn about potential security
problems when they contain a dot "." (U+002e), but SHOULD accept and
pass all other non-empty userinfo sections that conform to URI syntax
in a User header.
The User header MAY appear in requests and MUST NOT occur in
responses.
When sending it, the user agent SHOULD generate User as the next
header field after Host. Transparent intermediates such as proxies
and caches MUST NOT add, remove or modify the User header. The
CONNECT method and Host header both exclude this information, and the
User header completes it.
Servers MAY ignore the User header [Section 3.2.1 of [RFC7230]].
When they use it, the Effective Request URI [Section 5.5 of
[RFC7230]] is constructed with the userinfo and the at "@" delimiter
(U+0040) prefixed to the host name and optional port. Although
authentication is orthogonal to resource selection, the scope of a
realm is scoped under the authority section [Section 2.2 of
[RFC7235]] and so the userinfo partitions realms.
HTTP caches [RFC7234] derive no privacy or security concerns from the
User header, but they do need to to differentiate requests based on
it. To accommodate that, the Vary header [Section 7.1.4 of
[RFC7231]] MUST be generated by the server in the matching response,
and the header MUST either be a single "*" star (U+002a) or list the
"user" name, for all responses whose processing was influenced by the
User header. This requirement has no bearing on server software and
configurations that ignore the User header.
Van Rein Expires July 29, 2020 [Page 3]
Internet-Draft HTTP user@ January 2020
During redirects or other traversals to (relative) HTTP URIs, the
user name MUST be overwritten when the new URI specifies an authority
component, and it MUST be kept otherwise. User agents MUST refuse
URIs with non-empty userinfo sub-component that do not conform to the
User header grammar; user agents MUST send any other non-empty
userinfo sub-components as the value of the User header in requests
for the target URI.
4. Orthogonality of Authentication (Example)
The user name in a URI refines the resource selection process on a
host, but it is easily confused with the orthogonal concept of
authentication. Below is an example to demonstrate how these
concepts relate intuitively, but only as the result of access
control, which is a local choice on the server but not a
specification-driven connection. By demonstrating group access, the
example shows a less restrictive model that derives from this
orthogonality of concepts.
The remainder of this section is informative.
John and Mary both work at the Sales department of Example, Inc. John
has written a document and wants Mary to review it. Mary opens a
link to the document name space under the sales account at
https://sales@example.com/docs and her user agent sends:
GET /docs HTTP/1.1
Host: example.com
User: sales
The server redirects to add a slash, and when this is specific to the
sales account, it must inform caches about this with the Vary header:
HTTP/1.1 301 Moved Permanently
Location: /docs/
Vary: User
Since the new location lacks an authority component, this part is
retained from the referring URI, and the user agent redirects to
https://sales@example.com/docs/ and sends:
GET /docs/ HTTP/1.1
Host: example.com
User: sales
By this time, the server runs into access control, and decides that
it needs an authenticated client identity. To this end, it responds
with a challenge to the Documents realm:
Van Rein Expires July 29, 2020 [Page 4]
Internet-Draft HTTP user@ January 2020
HTTP/1.1 401 Unauthorized
WWW-Authenticate: Knock realm="Documents"
Vary: User
Mary's user agent needs to collect credentials, and may hint at the
user name "sales" from the URI but, this being the name of a shared
resource, Mary has no credentials and instead authenticates as
"mary":
GET /docs/ HTTP/1.1
Host: example.com
User: sales
Authorization: Knock realm="Documents", user="mary", ...
At some point, the server accepts Mary's authentication and proceeds
to access control. This phase checks if user "mary" may access realm
"Documents" of "https://sales@example.com" by checking that Mary
works for the Sales department. Once this is assured, the server
returns the requested document list:
HTTP/1.1 200 OK
Vary: User
Content-Type: text/html
...
<a href="/docs/review.cgi?docid=123">Review 123 now</a>
...
Mary clicks on the link to /docs/review.cgi?docid=123 and her user
agent sees a relative reference with no authority component, so this
is again used from the referring URI. The new URI therefore becomes
https://sales@example.com/docs/review.cgi?docid=123 for which the
user agent sends:
GET /docs/review.cgi?docid=123 HTTP/1.1
Host: example.com
User: sales
Authorization: Knock realm="Documents", user="mary", ...
After access control, the server starts the CGI script with
environment variables LOCAL_USER=sales and REMOTE_USER=mary of which
only the latter is an authenticated result. The script interprets
the LOCAL_USER as a group account and the REMOTE_USER as the acting
group member, and returns a page for review of the document and Mary
can get to work.
Van Rein Expires July 29, 2020 [Page 5]
Internet-Draft HTTP user@ January 2020
5. IANA Considerations
IANA adds the following entry to the Message Headers registry:
Header Field Name Template Protocol Status Reference
------------------ --------- --------- ------- ----------
User http TBD TBD:THIS_SPEC
6. Security Considerations
The User header field as defined herein is orthogonal to issues of
authentication or authorisation, and adds no security concerns.
7. Normative References
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/info/rfc7230>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014,
<https://www.rfc-editor.org/info/rfc7231>.
[RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
RFC 7234, DOI 10.17487/RFC7234, June 2014,
<https://www.rfc-editor.org/info/rfc7234>.
[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Authentication", RFC 7235,
DOI 10.17487/RFC7235, June 2014,
<https://www.rfc-editor.org/info/rfc7235>.
[RFC7542] DeKok, A., "The Network Access Identifier", RFC 7542,
DOI 10.17487/RFC7542, May 2015,
<https://www.rfc-editor.org/info/rfc7542>.
Van Rein Expires July 29, 2020 [Page 6]
Internet-Draft HTTP user@ January 2020
Appendix A. HTTP User Environment Variable
The following variable SHOULD be passed up to applications that run
on top of the HTTP stack in a server:
LOCAL_USER gives the HTTP User header value after grammar checking
and percent-decoding. Like the customary variables HTTP_HOST
and PATH_INFO, this specifies the resource being requested.
The HTTP_USER header does not describe the identity of the HTTP
client, which usually lands in REMOTE_USER after
authentication.
Author's Address
Rick van Rein
InternetWide.org
Haarlebrink 5
Enschede, Overijssel 7544 WP
The Netherlands
Email: rick@openfortress.nl
Van Rein Expires July 29, 2020 [Page 7]