Internet DRAFT - draft-findlay-ldap-groupofentries

draft-findlay-ldap-groupofentries






Network Working Group                                         A. Findlay
Internet-Draft                                            Skills 1st Ltd
Expires: March 16, 2008                               September 13, 2007


                  The LDAP groupOfEntries object class
                  draft-findlay-ldap-groupofentries-00

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Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   This memo describes the LDAP groupOfEntries object class which is a
   replacement for the existing groupOfNames class.  The new class
   permits the creation of empty groups.

   If approved as a Standards Track document, this document will update
   RFC4519 [2]

Document Intent

   This document is intended to be, after appropriate review and
   revision, submitted to the RFC Editor as a Standards Track document.
   Distribution of this memo is unlimited.  Technical discussion of this
   document will take place on the IETF LDAP Extensions mailing list
   <ldapext@ietf.org>.  Please send editorial comments directly to the
   author <andrew.findlay@skills-1st.co.uk>


1.  Introduction

   A groupOfNames object class has existed since the earliest X.521 [1]
   standard.  It has an identical definition in LDAP (RFC4519 [2]).  The
   class is used to define entries holding DN-valued member attributes,
   each value pointing to an entry that represents a single member of
   the group being described, or to another entry of type groupOfNames.

   groupOfNames is a structural object class, so it is often the only
   class used in the definition of group objects.

   Experience has shown that the definition of groupOfNames causes
   difficulties in practice.  In particular, the fact that 'member' is a
   mandatory attribute means that it is not possible to create an empty
   group or to delete the last member from a group.  This leads to
   artificial tricks such as making every group a member of itself, or
   adding a dummy member to every group when it is created.  These
   tricks in turn make the management of groups more complex and prone
   to error.  Groups are commonly used to control access to resources,
   so management errors can lead to security risks.

   There does not appear to be any good reason for the 'member'
   attribute to be mandatory.  This memo describes a new object class
   called groupOfEntries that is equivalent to groupOfNames in all other
   respects but which makes 'member' an optional attribute.


2.  The existing groupOfNames object class

   RFC4519 [2] contains this definition:

   The 'groupOfNames' object class is the basis of an entry that
   represents a set of named objects including information related to
   the purpose or maintenance of the set.  (Source: X.521 [1])

         ( 2.5.6.9 NAME 'groupOfNames'
            SUP top
            STRUCTURAL
            MUST ( member $
                  cn )
            MAY ( businessCategory $
                  seeAlso $
                  owner $
                  ou $
                  o $
                  description ) )

   The inclusion of 'member' in the 'MUST' section of the definition
   prevents empty groups from being created.


3.  The groupOfEntries object class

   The 'groupOfEntries' object class is the basis of an entry that
   represents a set of named objects including information related to
   the purpose or maintenance of the set.  It should be used in
   preference to the 'groupOfNames' object class.

         ( 1.2.826.0.1.3458854.2.1.1.1 NAME 'groupOfEntries'
            SUP top
            STRUCTURAL
            MUST ( cn )
            MAY ( member $
                  businessCategory $
                  seeAlso $
                  owner $
                  ou $
                  o $
                  description ) )

   This object class allows groups to be empty.  In all other respects
   it behaves like the groupOfNames object class.

   The OID assigned to this object class is delegated by Skills 1st Ltd.


4.  Effect on other documents

   This draft deprecates the use of the groupOfNames object class in
   RFC4519 [2] and replaces it with the groupOfEntries class.


5.  IANA considerations

   It is requested that IANA register upon Standards Action the
   groupOfEntries Object Identifier Descriptor and its associated OID.


6.  Security considerations

   Groups are commonly used to define access permissions to directory
   entries and resources in other services.  Allowing for empty groups
   avoids the risks associated with leaving a dummy placeholder member
   in group entries, so security is improved.


Appendix A.  Acknowledgements

   The author gratefully acknowledges the contributions of Michael
   Stroeder to the first draft of this document.


7.  Informative References

   [1]  "The Directory: Selected Object Classes", ITU-T
        Recommendation X.521, March 1988.

   [2]  "LDAP: Schema for User Applications", RFC 4519, June 2006.


Author's Address

   Andrew Findlay
   Skills 1st Ltd
   2 Cedar Chase
   Taplow
   Maidenhead  SL6 0EU
   GB

   Phone: +44 1628 782565
   Email: andrew.findlay@skills-1st.co.uk
   URI:   http://www.skills-1st.co.uk/


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