RAP Working Group L-N. Hamer
Internet Draft B. Kosinski
Expires September 31, 2001 B. Gage
Nortel Networks
April 2001
Session Authorization for RSVP
draft-ietf-rap-rsvp-authsession-00.txt
Status of this Memo
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2001. Please send comments to the authors.
Copyright Notice
Copyright (C) The Internet Society (2001). All Rights Reserved.
Abstract
This document describes the representation of session authorization
information in the POLICY_DATA object [POL-EXT] for supporting
policy-based per-session authorization and admission control in
RSVP. The goal of session authorization is to allow the exchange
of information between network elements in order to authorize the
use of resources for a service and to co-ordinate actions between
the signaling and transport planes. This document describes how a
process on a system authorizes the reservation of resources by a
host and then provides that host with a session authorization
policy element which can be inserted into the RSVP PATH message to
facilitate proper and secure reservation of those resources within
the network. We describe the encoding of media authorization
information as RSVP policy elements and provide details relating to
operations, processing rules and error scenarios.
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1. Conventions used in this document
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 [RFC-2119].
2. Introduction
RSVP [RFC-2205] is a resource reservation setup protocol designed
for an integrated services [RFC-1633] or DiffEdge [RFC-2998]
Internet. The RSVP protocol is used by a host to request specific
qualities of service from the network for particular application
data streams or flows. RSVP is also used by routers to deliver
quality-of-service (QoS) requests to all nodes along the path(s) of
the flows and to establish and maintain state to provide the
requested service. RSVP requests will generally result in
resources being reserved in each node along the data path. RSVP
allows users to obtain preferential access to network resources,
under the control of an admission control mechanism. Such
admission control is often based on user or application identity
[I-REP], however, it is also valuable to provide the ability for
per-session admission control.
In order to allow for per-session admission control, it is necessary
to provide a mechanism for ensuring an RSVP request from a host has
been properly pre-authorized before allowing the reservation of
resources. In order to meet this requirement, there must be
information in the RSVP message which may be used to verify the
validity of the RSVP request. This may be done by providing the host
with a token upon authorization which may be inserted into the RSVP
PATH message and verified by the network.
We describe the session authorization element (AUTH_SESSION)
contained in the POLICY_DATA object. The user process must obtain an
AUTH_SESSION object from an authorizing entity, which it may then
pass to the RSVP process (service) on the originating host. The RSVP
service then inserts the AUTH_SESSION object into the RSVP PATH
message to allow verification of the network resource request.
Network elements, such as routers, verify the request and then admit
the RSVP message based on admission policy.
[S-AUTH] describes a framework in which a session authorization
policy element may be utilized to contain information relevant to
the network's decision to grant a reservation request.
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3. Policy Element for Session Authorization Data
3.1 Policy Data Object Format
POLICY_DATA objects contain policy information and are carried by
RSVP messages. A detail description of the format of POLICY_DATA
object can be found in "RSVP Extensions for Policy Control" [POL-
EXT].
3.2 Session Authorization Data Policy Element
In this section we describe a policy element (PE) called session
authorization data (AUTH_SESSION). The AUTH_SESSION policy element
contains a list of fields which describe the session, along with
other attributes.
+-------------+-------------+-------------+-------------+
| Length | P-Type = AUTH_SESSION |
+-------------+-------------+-------------+-------------+
// Session Authorization Attribute List //
+-------------------------------------------------------+
Length
The length of the policy element (including the Length and
P-Type) is in number of octets (MUST be in multiples of 4) and
indicates the end of the session authorization information
block.
P-Type (Session Authorization Type)
The Policy element type (P-type) of this element. The
Internet Assigned Numbers Authority (IANA) acts as a registry
for policy element types for identity as described in
[POL-EXT]. The definition for AUTH_SESSION is currently to be
defined.
Session Authorization Attribute List
The session authorization attribute list is a collection of
objects which describes the session and provides other
information necessary to verify the RSVP request.
3.3 Session Authorization Attributes
A session authorization attribute may contain a variety of
information and has both an attribute type and subtype. The
attribute itself MUST be a multiple of 4 octets in length, and any
attributes that are not a multiple of 4 octets long MUST be padded
to a 4-octet boundary.
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+--------+--------+--------+--------+
| Length | S-Type |SubType |
+--------+--------+--------+--------+
| Value ...
+--------+--------+--------+--------+
Length
The length field is two octets and indicates the actual length
of the attribute (including Length, S-Type and SubType fields)
in number of octets. The length does NOT include any bytes
padding to the value field to make the attribute a multiple of
4 octets long.
S-Type
Session authorization attribute type (S-Type) field is one
octet. IANA SHALL act as a registry for S-Types as described
in section 7, IANA Considerations. Initially, the registry
contains the following S-Types:
1 AUTH_ENT_ID The unique identifier of the entity
which authorized the session.
2 AUTH_ENT_CRED The credentials of the authorizing
entity, such as a digital
certificate.
3 SESSION_ID Unique identifier for this session.
4 SOURCE_ADDR Address specification for the
session originator.
5 DEST_ADDR Address specification for the
session end-point.
6 START_TIME The starting time for the session.
7 END_TIME The end time for the session.
8 RESOURCES The resources which the user is
authorized to request.
9 DIGITAL_SIGNATURE Digital signature of the session
authorization policy element.
SubType
Session authorization attribute sub-type is one octet in
length. The value of the SubType depends on the S-Type.
Value
The attribute specific information.
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3.3.1 Authorizing Entity Identifier
AUTH_ENT_ID is used to identify the entity which authorized the
initial service request and generated the session authorization
policy element. The AUTH_ENT_ID may be represented in various
formats, and the SubType is used to define the format for the ID.
The format for AUTH_ENT_ID is as follows:
+-------+-------+-------+-------+
| Length |S-Type |SubType|
+-------+-------+-------+-------+
| OctetString ...
+-------+-------+-------+-------+
Length
Length of the attribute, which MUST be >= 4.
S-Type
AUTH_ENT_ID
SubType
The following sub-types for AUTH_ENT_ID are defined. IANA
SHALL act as a registry for AUTH_ENT_ID sub-types as described
in section 7, IANA Considerations. Initially, the registry
contains the following sub-types of AUTH_ENT_ID:
1 IPV4_ADDRESS IPv4 address
2 IPV6_ADDRESS IPv6 address
3 FQDN Fully Qualified Domain Name
4 ASCII_DN X.500 Distinguished name as defined
in RFC-1779 as an ASCII string.
5 UNICODE_DN X.500 Distinguished name as defined
in RFC-1779 as a UNICODE string.
6 URI Universal Resource Identifier, as
defined in RFC-2396.
7 KRB_PRINCIPAL Kerberos principal name as defined in
RFC-1510.
OctetString
Contains the authorizing entity identifier.
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3.3.2 Authorizing Entity Credentials
AUTH_ENT_CRED contains the credentials of the authorizing entity,
which can then be used by the network to ensure that the entity
which generated this session authorization policy element is a
valid trusted entity.
+-------+-------+-------+-------+
| Length |S-Type |SubType|
+-------+-------+-------+-------+
| OctetString ...
+-------+-------+-------+-------+
Length
Length of the attribute, which MUST be >= 4.
S-Type
AUTH_ENT_CRED
SubType
The type of credentials contained in this attribute. IANA
SHALL act as a registry for AUTH_ENT_CRED sub-types as
described in section 7, IANA Considerations. Initially, the
registry contains the following sub-types:
1 ASCII_ID The authorizing entity identification in a
plain ASCII text string.
2 UNICODE_ID The authorizing entity identification in a
plain UNICODE text string.
3 X509_V3_CERT A chain of authorizing entity's X.509 V3
digital certificates.
4 PGP_CERT The PGP digital certificate of the
authorizing entity.
OctetString
Contains the authorizing entity credentials.
3.3.3 Session Identifier
SESSION_ID is a unique identifier for this session. It may be used
for a number of purposes, including replay detection, or even
mapping this request to a policy decision entry made by the
authorizing entity.
+-------+-------+-------+-------+
| Length |S-Type |SubType|
+-------+-------+-------+-------+
| OctetString ...
+-------+-------+-------+-------+
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Length
Length of the attribute, which MUST be >= 4.
S-Type
SESSION_ID
SubType
The following sub-types for SESSION_ID are defined. IANA
SHALL act as a registry for SESSION_ID sub-types as described
in section 7, IANA Considerations. Initially, the registry
contains the following sub-types of SESSION_ID:
1 ASCII_ID Simple plain ASCII string identifier.
2 UNICODE_ID Simple plain UNICODE string identifier.
3 OCTET_ID Raw octet string identifier.
OctetString
Contains the actual session identifier.
3.3.4 Source Address
SOURCE_ADDR is used to identify the source address specification of
the authorized session. This S-Type MAY be useful in some scenarios
to make sure the resource request has been authorized for that
particular source IP address and/or port.
+-------+-------+-------+-------+
| Length |S-Type |SubType|
+-------+-------+-------+-------+
| OctetString ...
+-------+-------+-------+-------+
Length
Length of the attribute, which MUST be >= 4.
S-Type
SOURCE_ADDR
SubType
The following sub types for SOURCE_ADDR are defined. IANA
SHALL act as a registry for SOURCE_ADDR sub-types as
described in section 7, IANA Considerations. Initially, the
registry contains the following sub types for SOURCE_ADDR:
1 IPV4_ADDRESS IPv4 address
2 IPV6_ADDRESS IPv6 address
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3 UDP_PORT UDP port specification
4 TCP_PORT TCP port specification
OctetString
The OctetString contains the source address information.
3.3.5 Destination Address
DEST_ADDR is used to identify the destination address of the
authorized session. This S-Type MAY be useful in some scenarios to
make sure the resource request has been authorized for that
particular destination IP address and/or port.
+-------+-------+-------+-------+
| Length |S-Type |SubType|
+-------+-------+-------+-------+
| OctetString ...
+-------+-------+-------+-------+
Length
Length of the attribute, which MUST be >= 4.
S-Type
DEST_ADDR
SubType
The following sub types for DEST_ADDR are defined. IANA SHALL
act as a registry for DEST_ADDR sub-types as described in
section 7, IANA Considerations. Initially, the registry
contains the following sub types for DEST_ADDR:
1 IPV4_ADDRESS IPv4 address
2 IPV6_ADDRESS IPv6 address
3 UDP_PORT UDP port specification
4 TCP_PORT TCP port specification
OctetString
The OctetString contains the destination address specification.
3.3.6 Start time
START_TIME is used to identify the start time of the authorized
session. This S-Type MAY be useful in some scenarios to specify a
start time for the authorized session.
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+-------+-------+-------+-------+
| Length |S-Type |SubType|
+-------+-------+-------+-------+
| OctetString ...
+-------+-------+-------+-------+
Length
Length of the attribute, which MUST be >= 4.
S-Type
START_TIME
SubType
The following sub types for START_TIME are defined. IANA SHALL
act as a registry for START_TIME sub-types as described in
section 7, IANA Considerations. Initially, the registry
contains the following sub types for START_TIME:
1 NTP_TIMESTAMP NTP Timestamp Format as defined in
RFC-1305.
OctetString
The OctetString contains the start time.
3.3.7 End time
END_TIME is used to identify the end time of the authorized
session. This S-Type MAY be useful in some scenarios to specify a
end time for the authorized session.
+-------+-------+-------+-------+
| Length |S-Type |SubType|
+-------+-------+-------+-------+
| OctetString ...
+-------+-------+-------+-------+
Length
Length of the attribute, which MUST be >= 4.
S-Type
END_TIME
SubType
The following sub types for END_TIME are defined. IANA SHALL
act as a registry for END_TIME sub-types as described in
section 7, IANA Considerations. Initially, the registry
contains the following sub types for END_TIME:
1 NTP_TIMESTAMP NTP Timestamp Format as defined in
RFC-1305.
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OctetString
The OctetString contains the end time.
3.3.8 Resources Authorized
RESOURCES is used to define the characteristics of the authorized
session. This S-Type MAY be useful in some scenarios to specify the
specific resources authorized to ensure the request fits the
authorized specifications.
+-------+-------+-------+-------+
| Length |S-Type |SubType|
+-------+-------+-------+-------+
| OctetString ...
+-------+-------+-------+-------+
Length
Length of the attribute, which MUST be >= 4.
S-Type
RESOURCES
SubType
The following sub-types for RESOURCES are defined. IANA SHALL
act as a registry for RESOURCES sub-types as described in
section 7, IANA Considerations. Initially, the registry
contains the following sub types for RESOURCES:
1 BANDWIDTH Maximum bandwidth (kbps) authorized.
2 FLOW_SPEC Flow spec specification as defined in
RFC-2205.
3 SDP SDP Media Descriptor as defined in
RFC-2327.
4 DSCP Differentiated services codepoint as
defined in RFC-2474.
OctetString
The OctetString contains the resources specification.
3.3.9 Digital Signature
The DIGITAL_SIGNATURE attribute contains the digital signature of
the AUTH_SESSION policy element and signs all the data in the
policy element up to the DIGITAL_SIGNATURE. If the
DIGITAL_SIGNATURE attribute has been included in the AUTH_SESSION
policy element, it MUST be the last attribute in the list.
A summary of DIGITAL_SIGNATURE attribute format is described below.
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+-------+-------+-------+-------+
| Length |S-Type |SubType|
+-------+-------+-------+-------+
| OctetString ...
+-------+-------+-------+-------+
Length
Length of the attribute, which MUST be >= 4.
S-Type
DIGITAL_SIGNATURE
SubType
The following sub-types for DIGITAL_SIGNATURE are
defined. IANA SHALL act as a registry for DIGITAL_SIGNATURE
sub-types as described in section 7, IANA
Considerations. Initially, the registry contains the following
sub types for DIGITAL_SIGNATURE:
1 DSA_SHA1 DSA signature using SHA1 [X.509].
2 RSA_SHA1 RSA signature using SHA1 [X.509].
3 RSA_MD5 RSA signature using MD5 [X.509].
4 HMAC_SHA1 HMAC with SHA1 [RFC 2104].
5 HMAC_MD5 HMAC with MD5 [RFC 2104].
OctetString
OctetString contains the digital signature of the AUTH_SESSION.
4. Framework
[S-AUTH] describes a framework in which the session authorization
policy element may be utilized to transport information for use in
authorizing resource reservation for media flows.
5. Message Processing Rules
5.1 Message Generation (RSVP Host)
An RSVP message is created as specified in [RFC-2205] with following
modifications.
1. RSVP message MUST contain at most one AUTH_SESSION policy element.
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2. A Session Authorization policy element (AUTH_SESSION) is created
and the IdentityType field is set to indicate the identity type
in the policy element. Only the required Session Authorization
attributes are added.
3. POLICY_DATA object (containing the AUTH_SESSION policy element)
is inserted in the RSVP message in the appropriate place.
5.2 Message Reception (Router)
RSVP message is processed as specified in [RFC-2205] with following
modifications.
1. If router is policy aware then it SHOULD send the RSVP
message to the PDP and wait for response. If the router is
policy unaware then it ignores the policy data objects and
continues processing the RSVP message.
2. Reject the message if the response from the PDP is negative.
3. Continue processing the RSVP message.
5.3 Authorization (Router/PDP)
1. Retrieve the AUTH_SESSION policy element. Check the PE type
field and return an error if the identity type is not supported.
2. Verify the authorizing entity credentials and message integrity.
- Pre-shared key authentication: Get entity ID, identify
appropriate pre-shared key for the authorizing entity, and
validate signature.
- Public Key: Validate the certificate chain against
trusted Certificate Authority (CA) and valide the
message signature using the public key.
- Kerberos Ticket: Request a ticket for the authorizing entity
from the local KDC. Use the ticket to access the authorizing
entity and obtain authentication data for the message (e.g.
the signing key) or the data itself.
3. Verify the requested QoS does not exceed the authorized QoS.
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6. Error Signaling
If PDP fails to verify the AUTH_SESSION policy element then it MUST
return policy control failure (Error Code = 02) to the PEP. The
error values are described in [RFC-2205] and [POL-EXT]. Also PDP
SHOULD supply a policy data object containing an AUTH_DATA
Policy Element with A-Type=POLICY_ERROR_CODE containing more
details on the Policy Control failure [I-REP]. The PEP
will include this Policy Data object in the outgoing RSVP Error
message.
7. IANA Considerations
Following the policies outlined in [IANA-CONSIDERATIONS], session
authorization attribute types (S-Type)in the range 0-127 are
allocated through an IETF Consensus action, S-Type values between
128-255 are reserved for Private Use and are not assigned by IANA.
Following the policies outlined in [IANA-CONSIDERATIONS],
AUTH_ENT_ID, AUTH_ENT_CRED, SESSION_ID, START_TIME, STOP_TIME,
SOURCE_IP, DEST_IP, RESOURCES and DIGITAL_SIGNATURE SubType values
in the range 0-127 are allocated through an IETF Consensus action,
SubType values between 128-255 are reserved for Private Use and are
not assigned by IANA.
8. Security Considerations
The purpose of this draft is to describe a mechanism for media
authorization to prevent theft of service. It does not cover other
possible security breaches such as IP spoofing.
9. Acknowledgments
We would like to thank Francois Audet, Don Wade, Hamid Syed, Matt
Broda, and many others for their valuable comments.
In addition, we would like to thank S. Yadav, et al, for their
efforts on RFC 2752, as this document borrows heavily from their
work.
10. References
[I-REP] S. Yadav et al, "Identity Representation for
RSVP", Internet-draft,
draft-ietf-rap-rsvp-newidentity-01.txt,
January 2000
[S-AUTH] Hamer, L-N. and Gage, B, "Framework for
session setup with media authorization",
Internet-Draft,
draft-hamer-rap-session-auth-00.txt,
February 2001.
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[ASCII] Coded Character Set -- 7-Bit American Standard
Code for Information Interchange, ANSI X3.4-
1986.
[IANA-CONSIDERATIONS] Alvestrand, H. and T. Narten, "Guidelines for
Writing an IANA Considerations Section in
RFCs", BCP 26, RFC 2434, October 1998.
[POL-EXT] Herzog, S., "RSVP Extensions for Policy
Control", RFC 2750, January 2000.
[POL-FRAME] Yavatkar, R., Pendarakis, D. and R. Guerin, "A
Framework for Policy-based Admission Control
RSVP", RFC 2753, January 2000.
[RFC-1305] Mills, David L., "Network Time Protocol
(Version 3) Specification, Implementation, and
Analysis", RFC 1305, March 1992.
[RFC-1510] Kohl, J. and C. Neuman, "The Kerberos Network
Authentication Service (V5)", RFC 1510,
September 1993.
[RFC-1633] Braden, R., Clark, D., Shenker, S.,
"Integrated Services in the Internet
Architecture: An Overview", RFC 1633,
June 1994.
[RFC-1779] Killie, S., "A String Representation of
Distinguished Names", RFC 1779, March 1995.
[RFC-2205] Braden, R., Zhang, L., Berson, S., Herzog, S.
and S. Jamin, "Resource ReSerVation Protocol
(RSVP) - Version 1 Functional Specification",
RFC 2205, September 1997.
[RFC-2209] Braden, R. and L. Zhang, "Resource ReSerVation
Protocol (RSVP) - Version 1 Message Processing
Rules", RFC 2209, September 1997.
[RFC-2327] Handley, M., Jacobson, V., "SDP: Session
Description Protocol", RFC 2327, April 1998.
[RFC-2396] Berners-Lee, T., Fielding, R., Irvine, U.C.,
Masinter, L., "Uniform Resource Identifiers
(URI): Generic Syntax", RFC 2396, August 1998.
[RFC-2474] Nichols, K., Blake, S., Baker, F., Black, D.,
"Definition of the Differentiated Services
Field (DS Field) in the IPv4 and IPv6
Headers", RFC 2474, December 1998.
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[RFC-2998] Bernet, Y., Ford, P., Yavatkar, R., Baker, F.,
Zhang, L., Speer, M., Braden, R., Davie, B.,
Wroclawski, J., Felstaine, E., "A Framework
for Integrated Services Operation over
Diffserv Networks", RFC 2998, November 2000.
[UNICODE] The Unicode Consortium, "The Unicode Standard,
Version 2.0", Addison-Wesley, Reading, MA,
1996.
[X.509] Housley, R., Ford, W., Polk, W. and D. Solo,
"Internet X.509 Public Key Infrastructure
Certificate and CRL Profile", RFC 2459, January
1999.
[X.509-ITU] ITU-T (formerly CCITT) Information technology -
Open Systems Interconnection - The Directory:
Authentication Framework Recommendation X.509
ISO/IEC 9594-8
11. Author Information
Louis-Nicolas Hamer
Nortel Networks
Ottawa, Canada
EMail: nhamer@nortelnetworks.com
Brett Kosinski
Nortel Networks
Ottawa, Canada
EMail: brettk@nortelnetworks.com
Bill Gage
Nortel Networks
Ottawa, Canada
EMail: gageb@nortelnetworks.com
12. Full Copyright Statement
Copyright (C) The Internet Society (2001). All Rights Reserved. This
document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph
are included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organisations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into.
Expiration Date
This memo is filed as <draft-ietf-rap-rsvp-authsession-00.txt>, and
expires September 31, 2001.
Expires September 2001 [Page 15]
