GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools

Problem, Formatting or Query -  Send Feedback

Was this page helpful?-10+1


rfc:rfc7569

Internet Engineering Task Force (IETF) D. Quigley Request for Comments: 7569 Category: Standards Track J. Lu ISSN: 2070-1721 Oracle

                                                             T. Haynes
                                                          Primary Data
                                                             July 2015
     Registry Specification for Mandatory Access Control (MAC)
                       Security Label Formats

Abstract

 In the past, Mandatory Access Control (MAC) systems have used very
 rigid policies that were implemented in particular protocols and
 platforms.  As MAC systems become more widely deployed, additional
 flexibility in mechanism and policy will be required.  While
 traditional trusted systems implemented Multi-Level Security (MLS)
 and integrity models, modern systems have expanded to include such
 technologies as type enforcement.  Due to the wide range of policies
 and mechanisms that need to be accommodated, it is unlikely that the
 use of a single security label format and model will be viable.
 To allow multiple MAC mechanisms and label formats to co-exist in a
 network, this document creates a registry of label format
 specifications.  This registry contains label format identifiers and
 provides for the association of each such identifier with a
 corresponding extensive document outlining the exact syntax and use
 of the particular label format.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for 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 this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc7569.

Quigley, et al. Standards Track [Page 1] RFC 7569 Labeled NFS Registry July 2015

Copyright Notice

 Copyright (c) 2015 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
 (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. Definitions .....................................................4
 3. Existing Label Format Specifications ............................4
    3.1. IP Security Option (IPSO), Basic Security Option (BSO) .....4
    3.2. Commercial IP Security Option (CIPSO) ......................5
    3.3. Common Architecture Label IPv6 Security Option (CALIPSO) ...5
    3.4. Flux Advanced Security Kernel (FLASK) ......................5
 4. Security Considerations .........................................5
 5. IANA Considerations .............................................5
    5.1. Initial Registry ...........................................6
    5.2. Adding a New Entry to the Registry .........................7
    5.3. Obsoleting a Label Format Specifier ........................8
    5.4. Modifying an Existing Entry in the Registry ................8
 6. References ......................................................9
    6.1. Normative References .......................................9
    6.2. Informative References .....................................9
 Acknowledgments ...................................................10
 Authors' Addresses ................................................10

Quigley, et al. Standards Track [Page 2] RFC 7569 Labeled NFS Registry July 2015

1. Introduction

  With the acceptance of security labels in several mainstream
  operating systems, the need to communicate labels between these
  systems becomes more important.  In a typical client-and-server
  scenario, the client request to the server acts as a subject trying
  to access an object on the server [RFC7204].  Unfortunately, these
  systems are diverse enough that attempts at establishing one common
  label format have been unsuccessful.  This is because systems
  implement different Mandatory Access Control (MAC) models, which
  typically do not share any common ground.
  One solution might be to define a single label format that consists
  of the union of the requirements of all MAC models/implementations,
  known at a given time.  This approach is not desirable, because it
  introduces an environment where either (1) many MAC models would
  have blank fields for many of the label's components or (2) many
  implementations would ignore altogether many of the values that are
  present.  The resulting complexity would be likely to result in a
  confusing situation in which the interaction of fields that are
  derived from different MAC models is never clearly specified and the
  addition of new models or extensions of existing models is unduly
  difficult.
  An additional consideration is that if a policy authority or
  identifier field is specified in the label format, it would require
  a robust description that would encompass multiple MAC models where
  an implementation would lock policy administration into the
  described model.
  Ideally, a mechanism to address this problem should allow the most
  flexibility possible in terms of policy administration while
  providing a specification that is sufficient to allow for
  implementation of the label format and understanding of the
  semantics of the label.  This means that the label format
  specification would ideally contain a syntactic description of the
  label format and a description of the semantics for each component
  in the label.  This allows protocols to specify the type of label
  and label semantics that it requires while leaving policy and policy
  administration to the individual organizations using the protocol in
  their environment.
  Policy administration within an organization is a difficult problem.
  This should not be made even more difficult by having to request
  permission from external entities when crafting new policy or just
  making department specific modifications to existing policies.  The
  policy authority field would allow a label format specification to
  specify a scheme for policy administration without forcing it on all

Quigley, et al. Standards Track [Page 3] RFC 7569 Labeled NFS Registry July 2015

  users of security labels.  However, by agreeing to implement a
  particular label format specification, the protocol agrees to that
  policy administration mechanism when processing labels of that type.
  This document creates a registry of label format specifications to
  allow multiple MAC mechanisms and label formats to co-exist in a
  network.  While the initial use of this registry is for the Network
  File System (NFS) protocol, it might also be referenced and used by
  other IETF protocols in the future.

2. Definitions

 Label Format Specifier:  an identifier used by the client to
    establish the syntactic format of the security label and the
    semantic meaning of its components.
 Label Format Specification:  a reference to a stable, public document
    that specifies the label format.
 Multi-Level Security (MLS):  a traditional model where subjects are
    given a security level (Unclassified, Secret, Top Secret, etc.)
    and objects are given security labels that mandate the access of
    the subject to the object (see [BL73] and [RFC2401]).
    (Although RFC 2401 has been obsoleted by RFC 4301, RFC 2401 is
    still the definitive reference for MLS as discussed in this
    document.)
 object:  a passive resource within the system that we wish to
    protect.  Objects can be entities such as files, directories,
    pipes, sockets, and many other system resources relevant to the
    protection of the system state.
 subject:  an active entity, usually a process, user, or client, that
    is requesting access to an object.

3. Existing Label Format Specifications

3.1. IP Security Option (IPSO), Basic Security Option (BSO)

 The "IP Security Option (IPSO)" label format is defined in [RFC1108].
 IANA has assigned IPv4 Option 130 to the IPSO Basic Security Option
 (BSO).  IPSO is the only IPv4 sensitivity label option implemented in
 commercial IP routers.  IPSO BSO continues to have widespread
 implementation in hosts, and widespread deployment.  For the purposes
 of this document, only the BSO labels in Table 1 on Page 3 of
 [RFC1108] are used.

Quigley, et al. Standards Track [Page 4] RFC 7569 Labeled NFS Registry July 2015

 In some locales, the BSO value "(Reserved 2)" is used for marking
 information that is considered "Restricted" by local policy, where
 "Restricted" is less sensitive than "Confidential" but more sensitive
 than "Unclassified".

3.2. Commercial IP Security Option (CIPSO)

 The "Commercial IP Security Option (CIPSO)" label format is
 documented in [CIPSO] and in [FIPS-188].  While [CIPSO] is long
 expired, it is widely supported in deployed MLS systems that support
 IPv4.  IANA has assigned IPv4 option number 134 to CIPSO.  CIPSO is
 defined ONLY as an IPv4 option.  IANA has never assigned any IPv6
 option value to CIPSO.

3.3. Common Architecture Label IPv6 Security Option (CALIPSO)

 The "Common Architecture Label IPv6 Security Option (CALIPSO)" label
 format is specified in [RFC5570] and is defined for IPv6.  As noted
 in Section 10 of [RFC5570], CALIPSO is a direct derivative of the
 IPv4 "Son of IPSO" (SIPSO); therefore, CALIPSO is NOT derived from
 CIPSO in any way.

3.4. Flux Advanced Security Kernel (FLASK)

 The Flux Advanced Security Kernel (FLASK) [FLASK99] is an
 implementation of an architecture to provide flexible support for
 security policies.  Section 2.1 of [FLASK99b] summarizes the
 architecture of FLASK and describes:
 1.  the interactions between a subsystem that enforces security
     policy decisions and a subsystem that makes those decisions.
 2.  the requirements on the components within each subsystem.

4. Security Considerations

 This document defines a mechanism to associate the Label Format
 Specifier identifier with a document outlining the syntax and format
 of a label.  There are no security considerations for such an
 association.  The label specification documents referenced by each
 registration entry should state security considerations for the label
 mechanism it specifies.

5. IANA Considerations

 This section provides guidance to the Internet Assigned Numbers
 Authority (IANA) regarding the creation of a new registry in
 accordance with [RFC5226].

Quigley, et al. Standards Track [Page 5] RFC 7569 Labeled NFS Registry July 2015

 Per this document, IANA has created a new registry called "Security
 Label Format Selection Registry".  The new registry has the following
 fields:
 Label Format Specifier:  An integer that maps to a particular label
    format, e.g., the CALIPSO label format defined by [RFC5570].  The
    namespace of this identifier has the range of 0..65535.
 Label Description:  A human-readable ASCII [RFC20] text string that
    describes the label format, e.g., "Common Architecture Label IPv6
    Security Option (CALIPSO)".  The length of this field is limited
    to 128 bytes.
 Status:  A short ASCII text string indicating the status of an entry
    in the registry.  The status field for most entries should have
    the value "active".  In the case where a label format selection
    entry is obsolete, the status field of the obsoleted entry should
    be "obsoleted by entry NNN".
 Label Format Specification:  A reference to a stable, public document
    that specifies the label format, e.g., a URL to [RFC5570].

5.1. Initial Registry

 The initial assignments of the registry are as follows:
 +---------------+---------------------+--------+--------------------+
 | Label Format  | Description         | Status | Reference          |
 | Specifier     |                     |        |                    |
 +---------------+---------------------+--------+--------------------+
 | 0             | Reserved            | -      | -                  |
 | 1 - 127       | Private Use         | -      | -                  |
 | 128 - 255     | Experimental Use    | -      | -                  |
 | 256           | CIPSO (tag type #1) | active | [FIPS-188]         |
 | 257           | CALIPSO [RFC5570]   | active | [RFC5570]          |
 | 258           | FLASK Security      | active | [FLASK99]          |
 |               | Context             |        |                    |
 | 259           | IPSO                | active | [RFC1108]          |
 | 260 - 65535   | Available for IANA  | -      | -                  |
 |               | Assignment          |        |                    |
 +---------------+---------------------+--------+--------------------+
                     Label Format Specifier Ranges
                                Table 1

Quigley, et al. Standards Track [Page 6] RFC 7569 Labeled NFS Registry July 2015

5.2. Adding a New Entry to the Registry

 A label format specification document is required to add a new entry
 to the "Security Label Format Selection Registry".  If the label
 format document is inside the RFC path, then the IANA Considerations
 section of the label format document should clearly reference the
 "Security Label Format Selection Registry" and request allocation of
 a new entry.  The well-known IANA policy Specification Required, as
 defined in Section 4.1 of [RFC5226], will be used to handle such
 requests.  Note that the "Specification Required" policy implies that
 this process requires a Designated Expert, i.e., adding a new entry
 to this registry requires both a published label format specification
 and a Designated Expert review.
 In reviewing the published label format specification, the Designated
 Expert should consider whether or not the specification provides
 sufficient semantics for the object and subject labels to enforce the
 MAC model and policy administration when deployed within an
 organization.  Another consideration is if the label format allows a
 correct and complete implementation of the protocol to process and
 enforce labels as a policy administration mechanism.  Finally, to
 reduce interoperability issues, the reviewer must determine if the
 new label format specification has clearly defined syntax and
 semantics for the proposed new labels.

Quigley, et al. Standards Track [Page 7] RFC 7569 Labeled NFS Registry July 2015

5.3. Obsoleting a Label Format Specifier

 In the case where a label format selector number is assigned to a
 label format and the label format specification is changed later, a
 new selector assignment should be requested.  The same Specification
 Required IANA policy applies to such requests.  The IANA
 Considerations section of the updated label format specification
 should be explicit regarding which old label selector assignment it
 obsoletes.  Below is an example of an obsoleted entry in the
 registry:
 +--------------+--------------------+-----------+-------------------+
 | Label Format | Description        | Status    | Reference         |
 | Specifier    |                    |           |                   |
 +--------------+--------------------+-----------+-------------------+
 | 0            | Reserved           | -         | -                 |
 | 1 - 127      | Private Use        | -         | -                 |
 | 128 - 255    | Experimental Use   | -         | -                 |
 | 256          | CIPSO (tag type    | active    | [FIPS-188]        |
 |              | #1)                |           |                   |
 | 257          | CALIPSO [RFC5570]  | active    | [RFC5570]         |
 | 258          | FLASK Security     | obsoleted | [FLASK99]         |
 |              | Context            | by 263    |                   |
 | ...          |                    |           |                   |
 | 263          | FLASK Security     | active    | [new spec URL]    |
 |              | Context (v2)       |           |                   |
 | 264 - 65535  | Available for IANA | -         | -                 |
 |              | Assignment         |           |                   |
 +--------------+--------------------+-----------+-------------------+
             Example Label Format Specifier Updated Ranges
                                Table 2

5.4. Modifying an Existing Entry in the Registry

 A request to modify either the Description or the published label
 format specification will also require the Specification Required
 IANA policy to be applied.  The Designated Expert reviewer will need
 to determine if the published label format specification either
 obsoletes the Label Format Specifier or updates the label syntax and/
 or model.  If the Label Format Specifier is obsoleted, then the
 reviewer will follow the process defined in Section 5.3.  Otherwise,
 for the update of the label syntax and/or the model, the reviewer
 will approve the change.

Quigley, et al. Standards Track [Page 8] RFC 7569 Labeled NFS Registry July 2015

6. References

6.1. Normative References

 [RFC20]    Cerf, V., "ASCII format for network interchange", STD 80,
            RFC 20, DOI 10.17487/RFC0020, October 1969,
            <http://www.rfc-editor.org/info/rfc20>.
 [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
            IANA Considerations Section in RFCs", BCP 26, RFC 5226,
            DOI 10.17487/RFC5226, May 2008,
            <http://www.rfc-editor.org/info/rfc5226>.

6.2. Informative References

 [BL73]     Bell, D. and L. LaPadula, "Secure Computer Systems:
            Mathematical Foundations and Model", Technical Report
            M74-244, The MITRE Corporation, Bedford, MA, May 1973.
 [CIPSO]    IETF CIPSO Working Group, "Commercial IP Security Option
            (CIPSO 2.2)", Work in Progress,
            draft-ietf-cipso-ipsecurity-01, July 1992.
 [FIPS-188] US National Institute of Standards and Technology,
            "Standard Security Labels for Information Transfer",
            Federal Information Processing Standards (FIPS) 188,
            September 1994, <http://csrc.nist.gov/publications/
            fips/fips188/fips188.pdf>.
 [FLASK99]  Spencer, R., Smalley, S., Loscocco, P., Hibler, M.,
            Andersen, D., and J. Lepreau, "The Flask Security
            Architecture: System Support for Diverse Security
            Policies", In Proceedings of the Eighth USENIX
            Security Symposium, pages 123-139, August 1999,
            <https://www.cs.cmu.edu/~dga/papers/
            flask-usenixsec99.pdf>.
 [FLASK99b] Secure Computing Corporation, "Assurance in the Fluke
            Microkernel Formal Security Policy Model", Document
            00-0930896A001 Rev B, 17 Feb 1999, Secure Computing
            Corporation, Roseville, MN, USA, February 1999,
            <http://www.cs.utah.edu/flux/fluke/html/fspm.ps.gz>.
 [RFC1108]  Kent, S., "U.S. Department of Defense Security Options for
            the Internet Protocol", RFC 1108, DOI 10.17487/RFC1108,
            November 1991, <http://www.rfc-editor.org/info/rfc1108>.

Quigley, et al. Standards Track [Page 9] RFC 7569 Labeled NFS Registry July 2015

 [RFC2401]  Kent, S. and R. Atkinson, "Security Architecture for the
            Internet Protocol", RFC 2401, DOI 10.17487/RFC2401,
            November 1998, <http://www.rfc-editor.org/info/rfc2401>.
 [RFC5570]  StJohns, M., Atkinson, R., and G. Thomas, "Common
            Architecture Label IPv6 Security Option (CALIPSO)", RFC
            5570, DOI 10.17487/RFC5570, July 2009,
            <http://www.rfc-editor.org/info/rfc5570>.
 [RFC7204]  Haynes, T., "Requirements for Labeled NFS", RFC 7204, DOI
            10.17487/RFC7204, April 2014,
            <http://www.rfc-editor.org/info/rfc7204>.

Acknowledgments

 Ran Atkinson contributed the text for IPSO.
 Dave Noveck helped detangle the terminology.
 Alexey Melnikov caught that a process was needed for modifying
 entries in the registry.

Authors' Addresses

 David P. Quigley
 Email: dpquigl@davequigley.com
 Jarrett Lu
 Oracle
 Email: jarrett.lu@oracle.com
 Thomas Haynes
 Primary Data, Inc.
 4300 El Camino Real Ste 100
 Los Altos, CA  94022
 United States
 Phone: +1 408 215 1519
 Email: thomas.haynes@primarydata.com

Quigley, et al. Standards Track [Page 10]

/data/webs/external/dokuwiki/data/pages/rfc/rfc7569.txt · Last modified: 2015/07/15 05:33 (external edit)