One document matched: draft-ietf-rap-rsvp-identity-02.txt
Differences from draft-ietf-rap-rsvp-identity-01.txt
Internet Draft Satyendra Yadav
File: <draft-ietf-rap-rsvp-identity-02.txt> Raj Yavatkar
Intel
Ramesh Pabbati
Peter Ford
Tim Moore
Microsoft
Shai Herzog
IPHighway
Identity Representation for RSVP
January 1999
Status of this Memo
This document is an Internet Draft. Internet Drafts are working
documents of the Internet Engineering Task Force (IETF), its Areas,
and its Working Groups. Note that other groups may also distribute
working documents as Internet Drafts.
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"working draft" or "work in progress".
To view the list Internet-Draft Shadow Directories, see
http://www.ietf.org/shadow.html.
A Revised Version of this draft document will be submitted to the
RFC editor as a Proposed Standard for the Internet Community.
Discussion and suggestions for improvement are requested. This
document will expire in July 1999. Distribution of this draft is
unlimited.
Copyright Notice
Copyright (C) The Internet Society (1999). All Rights Reserved.
1. Abstract
This document describes the representation of identity information
in POLICY_DATA object [POL-EXT] for supporting policy based
admission control in RSVP. The goal of identity representation is to
allow a process on a system to securely identify the owner and the
application of the communicating process (e.g. user id) and convey
this information in RSVP messages (PATH or RESV) in a secure manner.
We describe the encoding of identities as RSVP policy element. We
describe the processing rules to generate identity policy elements
for multicast merged flows. Subsequently, we describe
representations of user identities for Kerberos and Public Key based
user authentication mechanisms. In summary we describe the use of
this identity information in an operational setting.
2. 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].
3. Introduction
RSVP [RFC 2205] is a resource reservation setup protocol designed
for an integrated services Internet [RFC 1633]. RSVP is used by a
host to request specific quality of service (QoS) from the network
for particular application data streams or flows. RSVP is also used
by routers to deliver 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
particular users to obtain preferential access to network resources,
under the control of an admission control mechanism. Permission to
make a reservation is based both upon the availability of the
requested resources along the path of the data and upon satisfaction
of policy rules. Providing policy based admission control mechanism
based on user identity or application is one of the prime
requirements.
In order to solve these problems and implement user based policy
control it is required to identify the user making an RSVP request.
This document proposes a mechanism for sending identification
information in the RSVP messages and enables authorization decisions
based on policy and identity of the user requesting resources from
the network.
We describe the authentication policy element (AUTH_DATA) contained
in the POLICY_DATA object. User process can generates an AUTH_DATA
policy element and gives it to RSVP process (service) on the
originating host. RSVP service inserts AUTH_DATA into the RSVP
message to identify the owner (user) making the request for network
resources. Network elements, such as routers, authenticate user
using the credentials presented in the AUTH_DATA and admit the RSVP
message based on admission policy. After a request has been
authenticated, first hop router installs the RSVP state and forwards
the new policy element returned by the Policy Decision Point (PDP)
[POL-FRAME].
4. Policy Element for Authentication Data
4.1 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].
4.2 Authentication Data Policy Element
In this section, we describe a policy element (PE) called
authentication data (AUTH_DATA). AUTH_DATA policy element contains a
list of authentication attributes. Policy object containing
AUTH_DATA must be protected against replay attacks using INTEGRITY
object option as described in the [POL-EXT].
+-------------+-------------+-------------+-------------+
| Length | P-Type = Identity Type |
+-------------+-------------+-------------+-------------+
// Authentication Attribute List //
| |
+-------------------------------------------------------+
Length
The length of the policy element (including the Length and P-
Type) is in number of octets (must be a multiple of 4) and
indicates the end of the authentication attribute list.
Identity Type
Type of identity information contained in this Policy Element
supplied as the Policy element type (P-type). The Internet
Assigned Numbers Authority (IANA) acts as a registry for
identity types as described in the section 10, IANA
Considerations. Initially, the registry contains the following
identity types:
2 AUTH_USER authentication scheme to identify users
3 AUTH_APP authentication scheme to identify
applications
Reserved
Must be set to 0.
Authentication Attribute List
Authentication attributes contain information specific to
authentication method and type of AUTH DATA. The policy element
provides the mechanism for grouping a collection of
authentication attributes.
4.3 Authentication Attributes
Authentication attributes must be encoded as a multiple of 4 octets,
attributes that are not a multiple of 4 octets long must be padded
to a 4-octet boundary.
+--------+--------+--------+--------+
| Length | A-Type |SubType |
+--------+--------+--------+--------+
| Value à
+--------+--------+--------+--------+
Length
The length field is two octets and indicates the actual length
of the attribute (including the Length and A-Type fields) in
number of octets. The length does not include any bytes padding
the attribute to make it multiple of 4 octets long.
A-Type
Authentication attribute type (A-Type) field is one octet. IANA
acts as a registry for A-Types as described in the section 10,
IANA Considerations. Initially, the registry contains the
following A-Types:
1 POLICY_LOCATOR Unique string for locating the
admission policy (such as X.500 DN
described in [RFC 1779]).
2 CREDENTIAL User credential such as Kerberos
ticket, or digital certificate.
Application credential such as
application ID.
3 DIGITAL_SIGNATURE Digital signature of the
authentication data policy element.
4 POLICY_ERROR_OBJECT Detailed information on policy
failures.
SubType
Authentication attribute sub-type field is one octet. Value of
SubType depends on A-type.
Value:
The value field contains 0-65351 octets.
4.3.1 Policy Locator
POLICY_LOCATOR is used to locate the admission policy for the user
or application. Distinguished Name (DN) is unique for each User or
application hence a DN is used as policy locator.
+-------+-------+-------+-------+
| Length |A-Type |SubType|
+-------+-------+-------+-------+
| OctetString à
+-------+-------+-------+--------
Length
> 4
A-Type
POLICY_LOCATOR
SubType
Following sub types for POLICY_LOCATOR are defined.IANA acts as
a registry for POLICY_LOCATOR sub types as described in the
section 10, IANA Considerations. Initially, the registry
contains the following sub types for POLICY_LOCATOR:
1 ASCII DN OctetString contains the X.500 DN as described
in the RFC 1779 as an ASCII string.
2 UNICODE_DN OctetString contains the X.500 DN described in
the RFC 1779 as an UNICODE string.
3 ASCII_DN_ENCRYPT OctetString contains the encrypted X.500
DN. The Kerberos session key or digital
certificate private key is used for encryption.
For Kerberos encryption the format is the same
as returned from gss_seal [RFC 1509].
4 UNICODE_DN_ENCRYPT OctetString contains the encrypted
UNICODE X.500 DN. The Kerberos session key or
digital certificate private key is used for
encryption. For Kerberos encryption the format
is the same as returned from gss_seal [RFC
1509].
OctetString
The OctetString field contains the DN.
4.3.2 Credential
CREDENTIAL indicates the credential of the user or application to be
authenticated. For Kerberos authentication method the CREDENTIAL
object contains the Kerberos session ticket. For public key based
authentication this field contains a digital certificate.
A summary of the CREDENTIAL attribute format is shown below. The
fields are transmitted from left to right.
+-------+-------+-------+-------+
| Length |A-Type |SubType|
+-------+-------+-------+-------+
| OctetString à
+-------+-------+-------+--------
Length
> 4
A-Type
CREDENTIAL
SubType
IANA acts as a registry for CREDENTIAL sub types as described in
the section 10, IANA Considerations. Initially, the registry
contains the following sub types for CREDENTIAL:
1 ASCII_ID OctetString contains user or application
identification in plain ASCII text string.
2 UNICODE_ID OctetString contains user or application
identification in plain UNICODE text string.
3 KERBEROS_TKT OctetString contains Kerberos ticket.
4 X509_V3_CERT OctetString contains X.509 V3 digital
certificate [X.509].
5 PGP_CERT OctetString contains PGP digital certificate.
OctetString
The OctetString contains the user or application credential.
4.3.3 Digital Signature
The DIGITAL_SIGNATURE attribute must be the last attribute in the
attribute list and contains the digital signature of the AUTH_DATA
policy element. The digital signature signs all data in the
AUTH_DATA policy element up to the DIGITAL_SIGNATURE. The algorithm
used to compute the digital signature depends on the authentication
method specified by the CREDENTIAL SubType field.
A summary of DIGITAL_SIGNATURE attribute format is described below.
+-------+-------+-------+-------+
| Length |A-Type |SubType|
+-------+-------+-------+-------+
| OctetString à
+-------+-------+-------+--------
Length
> 4
A-Type
DIGITAL_SIGNATURE
SubType
No sub types for DIGITAL_SIGNATURE are currently defined. This
field must be set to 0.
OctetString
OctetString contains the digital signature of the AUTH_DATA.
4.3.4 Policy Error Object
This attribute is used to specify any errors associated with the
policy element. When a RSVP policy node (local policy decision point
or remote PDP) encounters a request that fails policy control due to
its Authentication Policy Element, it may add a POLICY_ERROR_CODE
containing additional information about the reason the failure
occurred into the policy element. This will then cause an
appropriate PATH_ERROR or RESV_ERROR message to be generated with
the policy element and appropriate RSVP error code in the message,
which is returned to the request's source.
The AUTH DATA policy element in the PATH or RSVP message does not
contain the POLICY_ERROR_OBJECT attribute.
+-------+-------+-------+-------+
| Length |A-Type | 0 |
+-------+-------+-------+-------+
| 0 (Reserved) |Error value |
+-------+-------+-------+-------+
| OctetString
+-------+-------+-------+--------
Length
>= 8
A-Type
POLICY_ERROR_CODE
Error Value
A 32-bit bit code containing the reason that the policy
decision point failed to process the policy element. The
standard values are
ERROR_NO_MORE_INFO 1 no information is available
UNKNOWN_CREDENTIAL 2 the credentials are unknown
NO_PRIVILEGES 3 the credential has no privilege
EXPIRED_CREDENTIAL 4 the credential has expired
IDENTITY_CHANGED 5 identity has changed
OctetString
The OctetString field contains information from the policy
decision point that may contain additional information about
the failure. For example
"MSFT", DEF_SUBNET FLOW_RATE, CONTROLLED LOAD, 10000, 10000,
1000, 0, 0, 1000, 1000
This example contains an identification string for the policy
decision point, more information about why the policy decision
point failed. In this case, the subnet default policy on Token
bucket rate failed and the flow spec that caused the failure is
also returned.
5. Authentication Data Formats
Authentication attributes are grouped in a policy element to
represent the identity credentials.
5.1 Simple User Authentication
In simple user authentication method the user login ID (in plain
ASCII or UNICODE text) is encoded as CREDENTIAL attribute. A summary
of the simple user AUTH_DATA policy element is shown below.
+--------------+--------------+--------------+--------------+
| Length | P-type = AUTH_USER |
+--------------+--------------+--------------+--------------+
| Length |POLICY_LOCATOR| SubType |
+--------------+--------------+--------------+--------------+
| OctetString (User's Distinguished Name) à
+--------------+--------------+--------------+--------------+
| Length |CREDENTIAL | ASCII_ID |
+--------------+--------------+--------------+--------------+
| OctetString (User's login ID) à
+--------------+--------------+--------------+--------------+
5.2 Kerberos User Authentication
Kerberos [RFC 1510] authentication uses a trusted third party (the
Kerberos Distribution Center û KDC) to provide for authentication of
the user to a network server. It is assumed that a KDC is present
and both host and verifier of authentication information (router or
PDP) implement Kerberos authentication.
A summary of the Kerberos AUTH_DATA policy element is shown below.
+--------------+--------------+--------------+--------------+
| Length | P-type (AUTH_USER) |
+--------------+--------------+--------------+--------------+
| Length |POLICY_LOCATOR| SubType |
+--------------+--------------+--------------+--------------+
| OctetString (User's Distinguished Name) à
+--------------+--------------+--------------+--------------+
| Length | CREDENTIAL | KERBEROS_TKT |
+--------------+--------------+--------------+--------------+
| OctetString (Kerberos Session Ticket) à
+--------------+--------------+--------------+--------------+
5.2.1. Operational Setting using Kerberos Identities
An RSVP enabled host is configured to construct and insert AUTH_DATA
policy element into RSVP messages that designate use of the Kerberos
authentication method (KERBEROS_TKT). Upon RSVP session
initialization, the user application contacts the KDC to obtain a
Kerberos ticket for the next network node or its PDP. A router when
generating a RSVP message contacts the KDC to obtain a Kerberos
ticket for the next hop network node or its PDP. The identity of the
PDP or next network hop can be statically configured, learned via
DHCP or maintained in a directory service. The Kerberos ticket is
sent to the next network node (which may be a router or host) in a
RSVP message. The KDC is used to validate the ticket and
authentication the user sending RSVP message.
5.3 Public Key based User Authentication
In public key based user authentication method digital certificate
is encoded as user credentials. The digital signature is used for
authenticating the user. A summary of the public key user AUTH_DATA
policy element is shown below.
+--------------+--------------+--------------+--------------+
| Length | P-type (AUTH_USER) |
+--------------+--------------+--------------+--------------+
| Length |POLICY_LOCATOR| SubType |
+--------------+--------------+--------------+--------------+
| OctetString (User's Distinguished Name) à
+--------------+--------------+--------------+--------------+
| Length | CREDENTIAL | SubType |
+--------------+--------------+--------------+--------------+
| OctetString (User's Digital Certificate)à
+--------------+--------------+--------------+--------------+
| Length |DIGITAL_SIGN. | 0 |
+--------------+--------------+--------------+--------------+
| OctetString (Digital signature) à
+--------------+--------------+--------------+--------------+
5.3.1. Operational Setting for public key based authentication
Public key based authentication assumes following:
- RSVP service requestors have a pair of keys (private key and
public key).
- Private key is secured with the user.
- Public keys are stored in digital certificates and a trusted
party, certificate authority (CA) issues these digital
certificates.
- The verifier (PDP or router) has the ability to verify the
digital certificate.
RSVP requestor uses its private key to generate DIGITAL_SIGNATURE.
User Authenticators (router, PDP) use the user's public key (stored
in the digital certificate) to verify the signature and authenticate
the user.
5.4 Simple Application Authentication
The application authentication method encodes the application
identification such as an executable filename as plain ASCII or
UNICODE text.
+----------------+--------------+--------------+--------------+
| Length | P-type = AUTH_APP |
+----------------+--------------+--------------+--------------+
| Length |POLICY_LOCATOR| SubType |
+----------------+--------------+--------------+--------------+
| OctetString (Application Distinguished Name) à
+----------------+--------------+--------------+--------------+
| Length | CREDENTIAL | ASCII_ID |
+----------------+--------------+--------------+--------------+
| OctetString (Application Id û ex: vic.exe)
+----------------+--------------+--------------+--------------+
6. Operation
+-----+ +-----+
| PDP |-------+ | PDP |
+-----+ | ààààààààààààà.àà. +-----+
| : : |
+--------+ : Transit : +-------+
+----| Router |------: Network : -------| Router|--+
| +--------+ : : +-------+ |
| | :àààààààààààààà...: | |
| | | |
Host A B C D
Figure 1: User and Application Authentication using AUTH_DATA PE
Network nodes (hosts/routers) generate AUTH_DATA policy elements,
contents of which are depends on the identity type used and the
authentication method used. But generally contains authentication
credentials (Kerberos ticket or digital certificate) and policy
locators (which can be the X.500 Distinguished Name of the user or
network node or application names). Network nodes generate AUTH_DATA
policy element containing the authentication identity when making the
RSVP request or forwarding an RSVP message.
Network nodes generate user AUTH_DATA policy element using the
following rules
1. For unicast sessions the user policy locator is the copied from
the previous hop. The authentication credentials are for the
current network node identity.
2. For multicast messages the user policy locator is for the current
network node identity. The authentication credentials are for the
current network node.
Network nodes generate application AUTH_DATA policy element using the
following rules:
1. For unicast sessions the application AUTH_DATA is the copied from
the previous hop.
2. For multicast messages the application AUTH_DATA is either the
first application AUTH_DATA in the message or chosen by the PDP.
7. Message Processing Rules
7.1 Message Generation (RSVP Host)
An RSVP message is created as specified in [RFC2205] with following
modifications.
1. RSVP message may contain multiple AUTH_DATA policy elements.
2. Authentication policy element (AUTH_DATA) is created and the
IdentityType field is set to indicate the identity type in the
policy element.
DN is inserted as POLICY_LOCATOR attribute.
Credentials such as Kerberos ticket or digital certificate are
inserted as the CREDENTIAL attribute.
3. POLICY_DATA object (containing the AUTH DATA policy element) is
inserted in the RSVP message in appropriate place. If INTEGRITY
object is not computed for the RSVP message then an INTEGRITY
object must be computed for this POLICY_DATA object, as described
in the [POL_EXT], and must be inserted as an Policy Data option.
7.2 Message Reception (Router)
RSVP message is processed as specified in [RFC2205] with following
modifications.
1. If router is not 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.
7.3 Authentication (Router/PDP)
1. Retrieve the AUTH_DATA policy element. Check the PE type field
and return an error if the identity type is not supported.
2. Verify user credential
- Simple authentication: e.g. Get user ID and validate it, or
get executable name and validate it.
- Kerberos: Send the Kerberos ticket to the KDC to obtain the
session key. Using the session key authenticate the user.
- Public Key: Validate the certificate that it was issued by a
trusted Certificate Authority (CA) and authenticate the user
or application by verifying the digital signature.
8. Error Signaling
If PDP fails to verify the AUTH_DATA policy element then it must
return Policy control failure (Error Code = 02) to PEP. The error
values are described in [RFC 2205] and [POL-EXT]. Also PDP must
supply a policy data object containing the AUTH DATA Policy Element
with more details on the Policy Control failures in the policy error
object attribute. The PEP will include this Policy Data object in
the outgoing RSVP Error message.
9. IANA Considerations
Following the policies outlined in [IANA-CONSIDERATIONS],
authentication attribute types (A-Type)in the range 0-127 are
allocated an IETF Consensus action, A-Type values between 128-255
are reserved for Private Use and are not assigned by IANA.
Following the policies outlined in [IANA-CONSIDERATIONS],
POLICY_LOCATOR SubType values in the range 0-127 are allocated an
IETF Consensus action, POLICY_LOCATOR SubType values between 128-255
are reserved for Private Use and are not assigned by IANA.
Following the policies outlined in [IANA-CONSIDERATIONS],
CREDENTIAL SubType values in the range 0-127 are allocated an IETF
Consensus action, CREDENTIAL SubType values between 128-255 are
reserved for Private Use and are not assigned by IANA.
10. Security Considerations
The purpose of this draft is to describe a mechanism to authenticate
RSVP requests based on user identity in a secure manner. RSVP
INTEGRITY object is used to protect the policy object containing
user identity information from security (replay) attacks. Combining
the AUTH_DATA policy element and the INTEGRITY object results in a
secure access control that enforces authentication based on both the
identity of the user and the identity of the originating node.
Simple authentication does not contain credential that can be
securely authenticated and is inherently less secured.
The Kerberos authentication mechanism is reasonably well secured.
User authentication using a public key certificate is known to
provide the strongest security.
11. Acknowledgments
We would like to thank Andrew Smith, Bob Lindell and many others for
their valuable comments on this draft.
12. References
[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."
Internet-Draft, draft-ietf-rap-policy-ext-02.txt,
January 1999.
[POL-FRAME] Yavatkar, R., et.al. "A Framework for Policy-based
Admission Control RSVP." Internet-Draft, draft-ietf-rap-
framework-01.txt, November 1998.
[RFC 1510] The Kerberos Network Authentication Service (V5). Kohl
J., Neuman, C. RFC 1510.
[RFC 1704] On Internet Authentication. Haller, N, Atkinson, R.,
RFC 1704.
[RFC 1779] A String Representation of Distinguished Names. S.
Kille. RFC 1779
[RFC 2205] Braden, R., et. al., "Resource ReSerVation Protocol
(RSVP) û Version 1 Functional Specification." RFC 2205.
[RFC 2209] Braden, R., Zhang, L., "Resource ReSerVation Protocol
(RSVP) - Version 1 Message Processing Rules." RFC 2209.
[UNICODE] The Unicode Consortium, "The Unicode Standard, Version
2.0", Addison-Wesley, Reading, MA, 1996.
[X.509] R. Housley, et. al., "Internet X.509 Public Key
Infrastructure Certificate and CRL Profile", Internet-
Draft, draft-ietf-pkix-ipki-part1-11.txt, September
1998.
[X.509-ITU] ITU-T (formerly CCITT) Information technology û Open
Systems Interconnection û The Directory: Authentication
Framework Recommendation X.509 ISO/IEC 9594-8
13. Author Information
Satyendra Yadav
Intel, JF3-206
2111 NE 25th Avenue
Hillsboro, OR 97124
Satyendra.Yadav@intel.com
Raj Yavatkar
Intel, JF3-206
2111 NE 25th Avenue
Hillsboro, OR 97124
Raj.Yavatkar@intel.com
Ramesh Pabbati
Microsoft
1 Microsoft Way
Redmond, WA 98054
rameshpa@microsoft.com
Peter Ford
Microsoft
1 Microsoft Way
Redmond, WA 98054
peterf@microsoft.com
Tim Moore
Microsoft
1 Microsoft Way
Redmond, WA 98054
timmoore@microsoft.com
Shai Herzog
IPHighway
2055 Gateway Pl., Suite 400
San Jose, CA 95110
herzog@iphighway.com
14. Full Copyright Statement
Copyright (C) The Internet Society (1999). 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 organizations, 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 languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."
Internet Draft Identity Representation for RSVP January 1999
Yadav, et al. 3
Yadav, et al. 1
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