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rfc:rfc3744

Network Working Group G. Clemm Request for Comments: 3744 IBM Category: Standards Track J. Reschke

                                                            greenbytes
                                                             E. Sedlar
                                                    Oracle Corporation
                                                          J. Whitehead
                                                       U.C. Santa Cruz
                                                              May 2004
         Web Distributed Authoring and Versioning (WebDAV)
                      Access Control Protocol

Status of this Memo

 This document specifies an Internet standards track protocol for the
 Internet community, and requests discussion and suggestions for
 improvements.  Please refer to the current edition of the "Internet
 Official Protocol Standards" (STD 1) for the standardization state
 and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (2004).  All Rights Reserved.

Abstract

 This document specifies a set of methods, headers, message bodies,
 properties, and reports that define Access Control extensions to the
 WebDAV Distributed Authoring Protocol.  This protocol permits a
 client to read and modify access control lists that instruct a server
 whether to allow or deny operations upon a resource (such as
 HyperText Transfer Protocol (HTTP) method invocations) by a given
 principal.  A lightweight representation of principals as Web
 resources supports integration of a wide range of user management
 repositories.  Search operations allow discovery and manipulation of
 principals using human names.

Clemm, et al. Standards Track [Page 1] RFC 3744 WebDAV Access Control Protocol May 2004

Table of Contents

 1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Terms. . . . . . . . . . . . . . . . . . . . . . . . . .  6
     1.2.  Notational Conventions . . . . . . . . . . . . . . . . .  8
 2.  Principals . . . . . . . . . . . . . . . . . . . . . . . . . .  8
 3.  Privileges . . . . . . . . . . . . . . . . . . . . . . . . . .  8
     3.1.  DAV:read Privilege . . . . . . . . . . . . . . . . . . . 10
     3.2.  DAV:write Privilege. . . . . . . . . . . . . . . . . . . 10
     3.3.  DAV:write-properties Privilege . . . . . . . . . . . . . 10
     3.4.  DAV:write-content Privilege. . . . . . . . . . . . . . . 11
     3.5.  DAV:unlock Privilege . . . . . . . . . . . . . . . . . . 11
     3.6.  DAV:read-acl Privilege . . . . . . . . . . . . . . . . . 11
     3.7.  DAV:read-current-user-privilege-set Privilege. . . . . . 12
     3.8.  DAV:write-acl Privilege. . . . . . . . . . . . . . . . . 12
     3.9.  DAV:bind Privilege . . . . . . . . . . . . . . . . . . . 12
     3.10. DAV:unbind Privilege . . . . . . . . . . . . . . . . . . 12
     3.11. DAV:all Privilege. . . . . . . . . . . . . . . . . . . . 13
     3.12. Aggregation of Predefined Privileges . . . . . . . . . . 13
 4.  Principal Properties . . . . . . . . . . . . . . . . . . . . . 13
     4.1.  DAV:alternate-URI-set. . . . . . . . . . . . . . . . . . 14
     4.2.  DAV:principal-URL. . . . . . . . . . . . . . . . . . . . 14
     4.3.  DAV:group-member-set . . . . . . . . . . . . . . . . . . 14
     4.4.  DAV:group-membership . . . . . . . . . . . . . . . . . . 14
 5.  Access Control Properties. . . . . . . . . . . . . . . . . . . 15
     5.1.  DAV:owner. . . . . . . . . . . . . . . . . . . . . . . . 15
           5.1.1. Example: Retrieving DAV:owner . . . . . . . . . . 15
           5.1.2. Example: An Attempt to Set DAV:owner. . . . . . . 16
     5.2.  DAV:group. . . . . . . . . . . . . . . . . . . . . . . . 18
     5.3.  DAV:supported-privilege-set. . . . . . . . . . . . . . . 18
           5.3.1. Example: Retrieving a List of Privileges
                  Supported on a Resource . . . . . . . . . . . . . 19
     5.4.  DAV:current-user-privilege-set . . . . . . . . . . . . . 21
           5.4.1. Example: Retrieving the User's Current Set of
                  Assigned Privileges . . . . . . . . . . . . . . . 22
     5.5.  DAV:acl. . . . . . . . . . . . . . . . . . . . . . . . . 23
           5.5.1. ACE Principal . . . . . . . . . . . . . . . . . . 23
           5.5.2. ACE Grant and Deny. . . . . . . . . . . . . . . . 25
           5.5.3. ACE Protection. . . . . . . . . . . . . . . . . . 25
           5.5.4. ACE Inheritance . . . . . . . . . . . . . . . . . 25
           5.5.5. Example: Retrieving a Resource's Access Control
                  List. . . . . . . . . . . . . . . . . . . . . . . 25
     5.6.  DAV:acl-restrictions . . . . . . . . . . . . . . . . . . 27
           5.6.1. DAV:grant-only. . . . . . . . . . . . . . . . . . 27
           5.6.2. DAV:no-invert ACE Constraint. . . . . . . . . . . 28
           5.6.3. DAV:deny-before-grant . . . . . . . . . . . . . . 28
           5.6.4. Required Principals . . . . . . . . . . . . . . . 28
           5.6.5. Example: Retrieving DAV:acl-restrictions. . . . . 28

Clemm, et al. Standards Track [Page 2] RFC 3744 WebDAV Access Control Protocol May 2004

     5.7.  DAV:inherited-acl-set. . . . . . . . . . . . . . . . . . 29
     5.8.  DAV:principal-collection-set . . . . . . . . . . . . . . 30
           5.8.1. Example: Retrieving DAV:principal-collection-set. 30
     5.9.  Example: PROPFIND to retrieve access control properties. 32
 6.  ACL Evaluation . . . . . . . . . . . . . . . . . . . . . . . . 36
 7.  Access Control and existing methods. . . . . . . . . . . . . . 37
     7.1.  Any HTTP method. . . . . . . . . . . . . . . . . . . . . 37
           7.1.1. Error Handling. . . . . . . . . . . . . . . . . . 37
     7.2.  OPTIONS. . . . . . . . . . . . . . . . . . . . . . . . . 38
           7.2.1. Example - OPTIONS . . . . . . . . . . . . . . . . 39
     7.3.  MOVE . . . . . . . . . . . . . . . . . . . . . . . . . . 39
     7.4.  COPY . . . . . . . . . . . . . . . . . . . . . . . . . . 39
     7.5.  LOCK . . . . . . . . . . . . . . . . . . . . . . . . . . 39
 8.  Access Control Methods . . . . . . . . . . . . . . . . . . . . 40
     8.1.  ACL. . . . . . . . . . . . . . . . . . . . . . . . . . . 40
           8.1.1. ACL Preconditions . . . . . . . . . . . . . . . . 40
           8.1.2. Example: the ACL method . . . . . . . . . . . . . 42
           8.1.3. Example: ACL method failure due to protected
                  ACE conflict. . . . . . . . . . . . . . . . . . . 43
           8.1.4. Example: ACL method failure due to an
                  inherited ACE conflict. . . . . . . . . . . . . . 44
           8.1.5. Example: ACL method failure due to an attempt
                  to set grant and deny in a single ACE . . . . . . 45
 9.  Access Control Reports . . . . . . . . . . . . . . . . . . . . 46
     9.1.  REPORT Method. . . . . . . . . . . . . . . . . . . . . . 46
     9.2.  DAV:acl-principal-prop-set Report. . . . . . . . . . . . 47
           9.2.1. Example: DAV:acl-principal-prop-set Report. . . . 48
     9.3.  DAV:principal-match REPORT . . . . . . . . . . . . . . . 49
           9.3.1. Example: DAV:principal-match REPORT . . . . . . . 50
     9.4.  DAV:principal-property-search REPORT . . . . . . . . . . 51
           9.4.1. Matching. . . . . . . . . . . . . . . . . . . . . 53
           9.4.2. Example: successful DAV:principal-property-search
                  REPORT. . . . . . . . . . . . . . . . . . . . . . 54
     9.5.  DAV:principal-search-property-set REPORT . . . . . . . . 56
           9.5.1. Example: DAV:principal-search-property-set
                  REPORT. . . . . . . . . . . . . . . . . . . . . . 58
 10. XML Processing . . . . . . . . . . . . . . . . . . . . . . . . 59
 11. Internationalization Considerations. . . . . . . . . . . . . . 59
 12. Security Considerations. . . . . . . . . . . . . . . . . . . . 60
     12.1. Increased Risk of Compromised Users. . . . . . . . . . . 60
     12.2. Risks of the DAV:read-acl and
           DAV:current-user-privilege-set Privileges. . . . . . . . 60
     12.3. No Foreknowledge of Initial ACL. . . . . . . . . . . . . 61
 13. Authentication . . . . . . . . . . . . . . . . . . . . . . . . 61
 14. IANA Considerations. . . . . . . . . . . . . . . . . . . . . . 62
 15. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 62

Clemm, et al. Standards Track [Page 3] RFC 3744 WebDAV Access Control Protocol May 2004

 16. References . . . . . . . . . . . . . . . . . . . . . . . . . . 62
     16.1. Normative References . . . . . . . . . . . . . . . . . . 62
     16.2. Informative References . . . . . . . . . . . . . . . . . 63
 Appendices
 A.  WebDAV XML Document Type Definition Addendum . . . . . . . . . 64
 B.  WebDAV Method Privilege Table (Normative). . . . . . . . . . . 67
 Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 71
 Full Copyright Statement. . . . . . . . . . . . .  . . . . . . . . 72

1. Introduction

 The goal of the WebDAV access control extensions is to provide an
 interoperable mechanism for handling discretionary access control for
 content and metadata managed by WebDAV servers.  WebDAV access
 control can be implemented on content repositories with security as
 simple as that of a UNIX file system, as well as more sophisticated
 models.  The underlying principle of access control is that who you
 are determines what operations you can perform on a resource.  The
 "who you are" is defined by a "principal" identifier; users, client
 software, servers, and groups of the previous have principal
 identifiers.  The "operations you can perform" are determined by a
 single "access control list" (ACL) associated with a resource.  An
 ACL contains a set of "access control entries" (ACEs), where each ACE
 specifies a principal and a set of privileges that are either granted
 or denied to that principal.  When a principal submits an operation
 (such as an HTTP or WebDAV method) to a resource for execution, the
 server evaluates the ACEs in the ACL to determine if the principal
 has permission for that operation.
 Since every ACE contains the identifier of a principal, client
 software operated by a human must provide a mechanism for selecting
 this principal.  This specification uses http(s) scheme URLs to
 identify principals, which are represented as WebDAV-capable
 resources.  There is no guarantee that the URLs identifying
 principals will be meaningful to a human.  For example,
 http://www.example.com/u/256432 and
 http://www.example.com/people/Greg.Stein are both valid URLs that
 could be used to identify the same principal.  To remedy this, every
 principal resource has the DAV:displayname property containing a
 human-readable name for the principal.
 Since a principal can be identified by multiple URLs, it raises the
 problem of determining exactly which principal is being referenced in
 a given ACE.  It is impossible for a client to determine that an ACE
 granting the read privilege to http://www.example.com/people/
 Greg.Stein also affects the principal at http://www.example.com/u/
 256432.  That is, a client has no mechanism for determining that two

Clemm, et al. Standards Track [Page 4] RFC 3744 WebDAV Access Control Protocol May 2004

 URLs identify the same principal resource.  As a result, this
 specification requires clients to use just one of the many possible
 URLs for a principal when creating ACEs.  A client can discover which
 URL to use by retrieving the DAV:principal-URL property (Section 4.2)
 from a principal resource.  No matter which of the principal's URLs
 is used with PROPFIND, the property always returns the same URL.
 With a system having hundreds to thousands of principals, the problem
 arises of how to allow a human operator of client software to select
 just one of these principals.  One approach is to use broad
 collection hierarchies to spread the principals over a large number
 of collections, yielding few principals per collection.  An example
 of this is a two level hierarchy with the first level containing 36
 collections (a-z, 0-9), and the second level being another 36,
 creating collections /a/a/, /a/b/, ..., /a/z/, such that a principal
 with last name "Stein" would appear at /s/t/Stein.  In effect, this
 pre-computes a common query, search on last name, and encodes it into
 a hierarchy.  The drawback with this scheme is that it handles only a
 small set of predefined queries, and drilling down through the
 collection hierarchy adds unnecessary steps (navigate down/up) when
 the user already knows the principal's name.  While organizing
 principal URLs into a hierarchy is a valid namespace organization,
 users should not be forced to navigate this hierarchy to select a
 principal.
 This specification provides the capability to perform substring
 searches over a small set of properties on the resources representing
 principals.  This permits searches based on last name, first name,
 user name, job title, etc.  Two separate searches are supported, both
 via the REPORT method, one to search principal resources
 (DAV:principal-property-search, Section 9.4), the other to determine
 which properties may be searched at all (DAV:principal-search-
 property-set, Section 9.5).
 Once a principal has been identified in an ACE, a server evaluating
 that ACE must know the identity of the principal making a protocol
 request, and must validate that that principal is who they claim to
 be, a process known as authentication.  This specification
 intentionally omits discussion of authentication, as the HTTP
 protocol already has a number of authentication mechanisms [RFC2617].
 Some authentication mechanism (such as HTTP Digest Authentication,
 which all WebDAV compliant implementations are required to support)
 must be available to validate the identity of a principal.

Clemm, et al. Standards Track [Page 5] RFC 3744 WebDAV Access Control Protocol May 2004

 The following issues are out of scope for this document:
 o  Access control that applies only to a particular property on a
    resource (excepting the access control properties DAV:acl and
    DAV:current-user-privilege-set), rather than the entire resource,
 o  Role-based security (where a role can be seen as a dynamically
    defined group of principals),
 o  Specification of the ways an ACL on a resource is initialized,
 o  Specification of an ACL that applies globally to all resources,
    rather than to a particular resource.
 o  Creation and maintenance of resources representing people or
    computational agents (principals), and groups of these.
 This specification is organized as follows.  Section 1.1 defines key
 concepts used throughout the specification, and is followed by a more
 in-depth discussion of principals (Section 2), and privileges
 (Section 3).  Properties defined on principals are specified in
 Section 4, and access control properties for content resources are
 specified in Section 5.  The ways ACLs are to be evaluated is
 described in Section 6.  Client discovery of access control
 capability using OPTIONS is described in Section 7.2.  Interactions
 between access control functionality and existing HTTP and WebDAV
 methods are described in the remainder of Section 7.  The access
 control setting method, ACL, is specified in Section 8.  Four reports
 that provide limited server-side searching capabilities are described
 in Section 9.  Sections on XML processing (Section 10),
 Internationalization considerations (Section 11), security
 considerations (Section 12), and authentication (Section 13) round
 out the specification.  An appendix (Appendix A) provides an XML
 Document Type Definition (DTD) for the XML elements defined in the
 specification.

1.1. Terms

 This document uses the terms defined in HTTP [RFC2616] and WebDAV
 [RFC2518].  In addition, the following terms are defined:
 principal
    A "principal" is a distinct human or computational actor that
    initiates access to network resources.  In this protocol, a
    principal is an HTTP resource that represents such an actor.

Clemm, et al. Standards Track [Page 6] RFC 3744 WebDAV Access Control Protocol May 2004

 group
    A "group" is a principal that represents a set of other
    principals.
 privilege
    A "privilege" controls access to a particular set of HTTP
    operations on a resource.
 aggregate privilege
    An "aggregate privilege" is a privilege that contains a set of
    other privileges.
 abstract privilege
    The modifier "abstract", when applied to a privilege on a
    resource, means the privilege cannot be set in an access control
    element (ACE) on that resource.
 access control list (ACL)
    An "ACL" is a list of access control elements that define access
    control to a particular resource.
 access control element (ACE)
    An "ACE" either grants or denies a particular set of (non-
    abstract) privileges for a particular principal.
 inherited ACE
    An "inherited ACE" is an ACE that is dynamically shared from the
    ACL of another resource.  When a shared ACE changes on the primary
    resource, it is also changed on inheriting resources.
 protected property
    A "protected property" is one whose value cannot be updated except
    by a method explicitly defined as updating that specific property.
    In particular, a protected property cannot be updated with a
    PROPPATCH request.

Clemm, et al. Standards Track [Page 7] RFC 3744 WebDAV Access Control Protocol May 2004

1.2. Notational Conventions

 The augmented BNF used by this document to describe protocol elements
 is described in Section 2.1 of [RFC2616].  Because this augmented BNF
 uses the basic production rules provided in Section 2.2 of [RFC2616],
 those rules apply to this document as well.
 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 [RFC2119].
 Definitions of XML elements in this document use XML element type
 declarations (as found in XML Document Type Declarations), described
 in Section 3.2 of [REC-XML].  When an XML element type in the "DAV:"
 namespace is referenced in this document outside of the context of an
 XML fragment, the string "DAV:" will be prefixed to the element name.

2. Principals

 A principal is a network resource that represents a distinct human or
 computational actor that initiates access to network resources.
 Users and groups are represented as principals in many
 implementations; other types of principals are also possible.  A URI
 of any scheme MAY be used to identify a principal resource.  However,
 servers implementing this specification MUST expose principal
 resources at an http(s) URL, which is a privileged scheme that points
 to resources that have additional properties, as described in Section
 4.  So, a principal resource can have multiple URIs, one of which has
 to be an http(s) scheme URL.  Although an implementation SHOULD
 support PROPFIND and MAY support PROPPATCH to access and modify
 information about a principal, it is not required to do so.
 A principal resource may be a group, where a group is a principal
 that represents a set of other principals, called the members of the
 group.  If a person or computational agent matches a principal
 resource that is a member of a group, they also match the group.
 Membership in a group is recursive, so if a principal is a member of
 group GRPA, and GRPA is a member of group GRPB, then the principal is
 also a member of GRPB.

3. Privileges

 Ability to perform a given method on a resource MUST be controlled by
 one or more privileges.  Authors of protocol extensions that define
 new HTTP methods SHOULD specify which privileges (by defining new
 privileges, or mapping to ones below) are required to perform the
 method.  A principal with no privileges to a resource MUST be denied
 any HTTP access to that resource, unless the principal matches an ACE

Clemm, et al. Standards Track [Page 8] RFC 3744 WebDAV Access Control Protocol May 2004

 constructed using the DAV:all, DAV:authenticated, or
 DAV:unauthenticated pseudo-principals (see Section 5.5.1).  Servers
 MUST report a 403 "Forbidden" error if access is denied, except in
 the case where the privilege restricts the ability to know the
 resource exists, in which case 404 "Not Found" may be returned.
 Privileges may be containers of other privileges, in which case they
 are termed "aggregate privileges".  If a principal is granted or
 denied an aggregate privilege, it is semantically equivalent to
 granting or denying each of the aggregated privileges individually.
 For example, an implementation may define add-member and remove-
 member privileges that control the ability to add and remove a member
 of a group.  Since these privileges control the ability to update the
 state of a group, these privileges would be aggregated by the
 DAV:write privilege on a group, and granting the DAV:write privilege
 on a group would also grant the add-member and remove-member
 privileges.
 Privileges may be declared to be "abstract" for a given resource, in
 which case they cannot be set in an ACE on that resource.  Aggregate
 and non-aggregate privileges are both capable of being abstract.
 Abstract privileges are useful for modeling privileges that otherwise
 would not be exposed via the protocol.  Abstract privileges also
 provide server implementations with flexibility in implementing the
 privileges defined in this specification.  For example, if a server
 is incapable of separating the read resource capability from the read
 ACL capability, it can still model the DAV:read and DAV:read-acl
 privileges defined in this specification by declaring them abstract,
 and containing them within a non-abstract aggregate privilege (say,
 read-all) that holds DAV:read, and DAV:read-acl.  In this way, it is
 possible to set the aggregate privilege, read-all, thus coupling the
 setting of DAV:read and DAV:read-acl, but it is not possible to set
 DAV:read, or DAV:read-acl individually.  Since aggregate privileges
 can be abstract, it is also possible to use abstract privileges to
 group or organize non-abstract privileges.  Privilege containment
 loops are not allowed; therefore, a privilege MUST NOT contain
 itself.  For example, DAV:read cannot contain DAV:read.
 The set of privileges that apply to a particular resource may vary
 with the DAV:resourcetype of the resource, as well as between
 different server implementations.  To promote interoperability,
 however, this specification defines a set of well-known privileges
 (e.g., DAV:read, DAV:write, DAV:read-acl, DAV:write-acl, DAV:read-
 current-user-privilege-set, and DAV:all), which can at least be used
 to classify the other privileges defined on a particular resource.
 The access permissions on null resources (defined in [RFC2518],
 Section 3) are solely those they inherit (if any), and they are not
 discoverable (i.e., the access control properties specified in

Clemm, et al. Standards Track [Page 9] RFC 3744 WebDAV Access Control Protocol May 2004

 Section 5 are not defined on null resources).  On the transition from
 null to stateful resource, the initial access control list is set by
 the server's default ACL value policy (if any).
 Server implementations MAY define new privileges beyond those defined
 in this specification.  Privileges defined by individual
 implementations MUST NOT use the DAV: namespace, and instead should
 use a namespace that they control, such as an http scheme URL.

3.1. DAV:read Privilege

 The read privilege controls methods that return information about the
 state of the resource, including the resource's properties.  Affected
 methods include GET and PROPFIND.  Any implementation-defined
 privilege that also controls access to GET and PROPFIND must be
 aggregated under DAV:read - if an ACL grants access to DAV:read, the
 client may expect that no other privilege needs to be granted to have
 access to GET and PROPFIND.  Additionally, the read privilege MUST
 control the OPTIONS method.
 <!ELEMENT read EMPTY>

3.2. DAV:write Privilege

 The write privilege controls methods that lock a resource or modify
 the content, dead properties, or (in the case of a collection)
 membership of the resource, such as PUT and PROPPATCH.  Note that
 state modification is also controlled via locking (see section 5.3 of
 [RFC2518]), so effective write access requires that both write
 privileges and write locking requirements are satisfied.  Any
 implementation-defined privilege that also controls access to methods
 modifying content, dead properties or collection membership must be
 aggregated under DAV:write, e.g., if an ACL grants access to
 DAV:write, the client may expect that no other privilege needs to be
 granted to have access to PUT and PROPPATCH.
 <!ELEMENT write EMPTY>

3.3. DAV:write-properties Privilege

 The DAV:write-properties privilege controls methods that modify the
 dead properties of the resource, such as PROPPATCH.  Whether this
 privilege may be used to control access to any live properties is
 determined by the implementation.  Any implementation-defined
 privilege that also controls access to methods modifying dead
 properties must be aggregated under DAV:write-properties - e.g., if

Clemm, et al. Standards Track [Page 10] RFC 3744 WebDAV Access Control Protocol May 2004

 an ACL grants access to DAV:write-properties, the client can safely
 expect that no other privilege needs to be granted to have access to
 PROPPATCH.
 <!ELEMENT write-properties EMPTY>

3.4. DAV:write-content Privilege

 The DAV:write-content privilege controls methods that modify the
 content of an existing resource, such as PUT.  Any implementation-
 defined privilege that also controls access to content must be
 aggregated under DAV:write-content - e.g., if an ACL grants access to
 DAV:write-content, the client can safely expect that no other
 privilege needs to be granted to have access to PUT.  Note that PUT -
 when applied to an unmapped URI - creates a new resource and
 therefore is controlled by the DAV:bind privilege on the parent
 collection.
 <!ELEMENT write-content EMPTY>

3.5. DAV:unlock Privilege

 The DAV:unlock privilege controls the use of the UNLOCK method by a
 principal other than the lock owner (the principal that created a
 lock can always perform an UNLOCK).  While the set of users who may
 lock a resource is most commonly the same set of users who may modify
 a resource, servers may allow various kinds of administrators to
 unlock resources locked by others.  Any privilege controlling access
 by non-lock owners to UNLOCK MUST be aggregated under DAV:unlock.
 A lock owner can always remove a lock by issuing an UNLOCK with the
 correct lock token and authentication credentials.  That is, even if
 a principal does not have DAV:unlock privilege, they can still remove
 locks they own.  Principals other than the lock owner can remove a
 lock only if they have DAV:unlock privilege and they issue an UNLOCK
 with the correct lock token.  Lock timeout is not affected by the
 DAV:unlock privilege.
 <!ELEMENT unlock EMPTY>

3.6. DAV:read-acl Privilege

 The DAV:read-acl privilege controls the use of PROPFIND to retrieve
 the DAV:acl property of the resource.
 <!ELEMENT read-acl EMPTY>

Clemm, et al. Standards Track [Page 11] RFC 3744 WebDAV Access Control Protocol May 2004

3.7. DAV:read-current-user-privilege-set Privilege

 The DAV:read-current-user-privilege-set privilege controls the use of
 PROPFIND to retrieve the DAV:current-user-privilege-set property of
 the resource.
 Clients are intended to use this property to visually indicate in
 their UI items that are dependent on the permissions of a resource,
 for example, by graying out resources that are not writable.
 This privilege is separate from DAV:read-acl because there is a need
 to allow most users access to the privileges permitted the current
 user (due to its use in creating the UI), while the full ACL contains
 information that may not be appropriate for the current authenticated
 user.  As a result, the set of users who can view the full ACL is
 expected to be much smaller than those who can read the current user
 privilege set, and hence distinct privileges are needed for each.
 <!ELEMENT read-current-user-privilege-set EMPTY>

3.8. DAV:write-acl Privilege

 The DAV:write-acl privilege controls use of the ACL method to modify
 the DAV:acl property of the resource.
 <!ELEMENT write-acl EMPTY>

3.9. DAV:bind Privilege

 The DAV:bind privilege allows a method to add a new member URL to the
 specified collection (for example via PUT or MKCOL).  It is ignored
 for resources that are not collections.
 <!ELEMENT bind EMPTY>

3.10. DAV:unbind Privilege

 The DAV:unbind privilege allows a method to remove a member URL from
 the specified collection (for example via DELETE or MOVE).  It is
 ignored for resources that are not collections.
 <!ELEMENT unbind EMPTY>

Clemm, et al. Standards Track [Page 12] RFC 3744 WebDAV Access Control Protocol May 2004

3.11. DAV:all Privilege

 DAV:all is an aggregate privilege that contains the entire set of
 privileges that can be applied to the resource.
 <!ELEMENT all EMPTY>

3.12. Aggregation of Predefined Privileges

 Server implementations are free to aggregate the predefined
 privileges (defined above in Sections 3.1-3.10) subject to the
 following limitations:
 DAV:read-acl MUST NOT contain DAV:read, DAV:write, DAV:write-acl,
 DAV:write-properties, DAV:write-content, or DAV:read-current-user-
 privilege-set.
 DAV:write-acl MUST NOT contain DAV:write, DAV:read, DAV:read-acl, or
 DAV:read-current-user-privilege-set.
 DAV:read-current-user-privilege-set MUST NOT contain DAV:write,
 DAV:read, DAV:read-acl, or DAV:write-acl.
 DAV:write MUST NOT contain DAV:read, DAV:read-acl, or DAV:read-
 current-user-privilege-set.
 DAV:read MUST NOT contain DAV:write, DAV:write-acl, DAV:write-
 properties, or DAV:write-content.
 DAV:write MUST contain DAV:bind, DAV:unbind, DAV:write-properties and
 DAV:write-content.

4. Principal Properties

 Principals are manifested to clients as a WebDAV resource, identified
 by a URL.  A principal MUST have a non-empty DAV:displayname property
 (defined in Section 13.2 of [RFC2518]), and a DAV:resourcetype
 property (defined in Section 13.9 of [RFC2518]).  Additionally, a
 principal MUST report the DAV:principal XML element in the value of
 the DAV:resourcetype property.  The element type declaration for
 DAV:principal is:
 <!ELEMENT principal EMPTY>

Clemm, et al. Standards Track [Page 13] RFC 3744 WebDAV Access Control Protocol May 2004

 This protocol defines the following additional properties for a
 principal.  Since it can be expensive for a server to retrieve access
 control information, the name and value of these properties SHOULD
 NOT be returned by a PROPFIND allprop request (as defined in Section
 12.14.1 of [RFC2518]).

4.1. DAV:alternate-URI-set

 This protected property, if non-empty, contains the URIs of network
 resources with additional descriptive information about the
 principal.  This property identifies additional network resources
 (i.e., it contains one or more URIs) that may be consulted by a
 client to gain additional knowledge concerning a principal.  One
 expected use for this property is the storage of an LDAP [RFC2255]
 scheme URL.  A user-agent encountering an LDAP URL could use LDAP
 [RFC2251] to retrieve additional machine-readable directory
 information about the principal, and display that information in its
 user interface.  Support for this property is REQUIRED, and the value
 is empty if no alternate URI exists for the principal.
 <!ELEMENT alternate-URI-set (href*)>

4.2. DAV:principal-URL

 A principal may have many URLs, but there must be one "principal URL"
 that clients can use to uniquely identify a principal.  This
 protected property contains the URL that MUST be used to identify
 this principal in an ACL request.  Support for this property is
 REQUIRED.
 <!ELEMENT principal-URL (href)>

4.3. DAV:group-member-set

 This property of a group principal identifies the principals that are
 direct members of this group.  Since a group may be a member of
 another group, a group may also have indirect members (i.e., the
 members of its direct members).  A URL in the DAV:group-member-set
 for a principal MUST be the DAV:principal-URL of that principal.
 <!ELEMENT group-member-set (href*)>

4.4. DAV:group-membership

 This protected property identifies the groups in which the principal
 is directly a member.  Note that a server may allow a group to be a
 member of another group, in which case the DAV:group-membership of

Clemm, et al. Standards Track [Page 14] RFC 3744 WebDAV Access Control Protocol May 2004

 those other groups would need to be queried in order to determine the
 groups in which the principal is indirectly a member.  Support for
 this property is REQUIRED.
 <!ELEMENT group-membership (href*)>

5. Access Control Properties

 This specification defines a number of new properties for WebDAV
 resources.  Access control properties may be retrieved just like
 other WebDAV properties, using the PROPFIND method.  Since it is
 expensive, for many servers, to retrieve access control information,
 a PROPFIND allprop request (as defined in Section 12.14.1 of
 [RFC2518]) SHOULD NOT return the names and values of the properties
 defined in this section.
 Access control properties (especially DAV:acl and DAV:inherited-acl-
 set) are defined on the resource identified by the Request-URI of a
 PROPFIND request.  A direct consequence is that if the resource is
 accessible via multiple URI, the value of access control properties
 is the same across these URI.
 HTTP resources that support the WebDAV Access Control Protocol MUST
 contain the following properties.  Null resources (described in
 Section 3 of [RFC2518]) MUST NOT contain the following properties.

5.1. DAV:owner

 This  property identifies a particular principal as being the "owner"
 of the resource.  Since the owner of a resource often has special
 access control capabilities (e.g., the owner frequently has permanent
 DAV:write-acl privilege), clients might display the resource owner in
 their user interface.
 Servers MAY implement DAV:owner as protected property and MAY return
 an empty DAV:owner element as property value in case no owner
 information is available.
 <!ELEMENT owner (href?)>

5.1.1. Example: Retrieving DAV:owner

 This example shows a client request for the value of the DAV:owner
 property from a collection resource with URL http://www.example.com/
 papers/.  The principal making the request is authenticated using
 Digest authentication.  The value of DAV:owner is the URL http://
 www.example.com/acl/users/gstein, wrapped in the DAV:href XML
 element.

Clemm, et al. Standards Track [Page 15] RFC 3744 WebDAV Access Control Protocol May 2004

 >> Request <<
 PROPFIND /papers/ HTTP/1.1
 Host: www.example.com
 Content-type: text/xml; charset="utf-8"
 Content-Length: xxx
 Depth: 0
 Authorization: Digest username="jim",
   realm="users@example.com", nonce="...",
   uri="/papers/", response="...", opaque="..."
 <?xml version="1.0" encoding="utf-8" ?>
 <D:propfind xmlns:D="DAV:">
   <D:prop>
     <D:owner/>
   </D:prop>
 </D:propfind>
 >> Response <<
 HTTP/1.1 207 Multi-Status
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxx
 <?xml version="1.0" encoding="utf-8" ?>
 <D:multistatus xmlns:D="DAV:">
   <D:response>
     <D:href>http://www.example.com/papers/</D:href>
     <D:propstat>
       <D:prop>
         <D:owner>
           <D:href>http://www.example.com/acl/users/gstein</D:href>
         </D:owner>
       </D:prop>
       <D:status>HTTP/1.1 200 OK</D:status>
     </D:propstat>
   </D:response>
 </D:multistatus>

5.1.2. Example: An Attempt to Set DAV:owner

 The following example shows a client request to modify the value of
 the DAV:owner property on the resource with URL <http://
 www.example.com/papers>.  Since DAV:owner is a protected property on
 this particular server, it responds with a 207 (Multi-Status)
 response that contains a 403 (Forbidden) status code for the act of
 setting DAV:owner.  Section 8.2.1 of [RFC2518] describes PROPPATCH
 status code information,  Section 11 of [RFC2518] describes the

Clemm, et al. Standards Track [Page 16] RFC 3744 WebDAV Access Control Protocol May 2004

 Multi-Status response and Sections 1.6 and 3.12 of [RFC3253] describe
 additional error marshaling for PROPPATCH attempts on protected
 properties.
 >> Request <<
 PROPPATCH /papers/ HTTP/1.1
 Host: www.example.com
 Content-type: text/xml; charset="utf-8"
 Content-Length: xxx
 Depth: 0
 Authorization: Digest username="jim",
   realm="users@example.com", nonce="...",
   uri="/papers/", response="...", opaque="..."
 <?xml version="1.0" encoding="utf-8" ?>
 <D:propertyupdate xmlns:D="DAV:">
   <D:set>
     <D:prop>
       <D:owner>
         <D:href>http://www.example.com/acl/users/jim</D:href>
       </D:owner>
     </D:prop>
   </D:set>
 </D:propertyupdate>
 >> Response <<
 HTTP/1.1 207 Multi-Status
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxx
 <?xml version="1.0" encoding="utf-8" ?>
 <D:multistatus xmlns:D="DAV:">
   <D:response>
     <D:href>http://www.example.com/papers/</D:href>
     <D:propstat>
       <D:prop><D:owner/></D:prop>
       <D:status>HTTP/1.1 403 Forbidden</D:status>
       <D:responsedescription>
         <D:error><D:cannot-modify-protected-property/></D:error>
         Failure to set protected property (DAV:owner)
       </D:responsedescription>
     </D:propstat>
   </D:response>
 </D:multistatus>

Clemm, et al. Standards Track [Page 17] RFC 3744 WebDAV Access Control Protocol May 2004

5.2. DAV:group

 This property identifies a particular principal as being the "group"
 of the resource.  This property is commonly found on repositories
 that implement the Unix privileges model.
 Servers MAY implement DAV:group as protected property and MAY return
 an empty DAV:group element as property value in case no group
 information is available.
 <!ELEMENT group (href?)>

5.3. DAV:supported-privilege-set

 This is a protected property that identifies the privileges defined
 for the resource.
 <!ELEMENT supported-privilege-set (supported-privilege*)>
 Each privilege appears as an XML element, where aggregate privileges
 list as sub-elements all of the privileges that they aggregate.
 <!ELEMENT supported-privilege
  (privilege, abstract?, description, supported-privilege*)>
 <!ELEMENT privilege ANY>
 An abstract privilege MUST NOT be used in an ACE for that resource.
 Servers MUST fail an attempt to set an abstract privilege.
 <!ELEMENT abstract EMPTY>
 A description is a human-readable description of what this privilege
 controls access to.  Servers MUST indicate the human language of the
 description using the xml:lang attribute and SHOULD consider the HTTP
 Accept-Language request header when selecting one of multiple
 available languages.
 <!ELEMENT description #PCDATA>
 It is envisioned that a WebDAV ACL-aware administrative client would
 list the supported privileges in a dialog box, and allow the user to
 choose non-abstract privileges to apply in an ACE.  The privileges
 tree is useful programmatically to map well-known privileges (defined
 by WebDAV or other standards groups) into privileges that are
 supported by any particular server implementation.  The privilege
 tree also serves to hide complexity in implementations allowing large
 number of privileges to be defined by displaying aggregates to the
 user.

Clemm, et al. Standards Track [Page 18] RFC 3744 WebDAV Access Control Protocol May 2004

5.3.1. Example: Retrieving a List of Privileges Supported on a Resource

 This example shows a client request for the DAV:supported-privilege-
 set property on the resource http://www.example.com/papers/.  The
 value of the DAV:supported-privilege-set property is a tree of
 supported privileges (using "[XML Namespace , localname]" to identify
 each privilege):
 [DAV:, all] (aggregate, abstract)
    |
    +-- [DAV:, read] (aggregate)
           |
           +-- [DAV:, read-acl] (abstract)
           +-- [DAV:, read-current-user-privilege-set] (abstract)
    |
    +-- [DAV:, write] (aggregate)
           |
           +-- [DAV:, write-acl] (abstract)
           +-- [DAV:, write-properties]
           +-- [DAV:, write-content]
    |
    +-- [DAV:, unlock]
 This privilege tree is not normative (except that it reflects the
 normative aggregation rules given in Section 3.12), and many possible
 privilege trees are possible.
 >> Request <<
 PROPFIND /papers/ HTTP/1.1
 Host: www.example.com
 Content-type: text/xml; charset="utf-8"
 Content-Length: xxx
 Depth: 0
 Authorization: Digest username="gclemm",
   realm="users@example.com", nonce="...",
   uri="/papers/", response="...", opaque="..."
 <?xml version="1.0" encoding="utf-8" ?>
 <D:propfind xmlns:D="DAV:">
   <D:prop>
     <D:supported-privilege-set/>
   </D:prop>
 </D:propfind>

Clemm, et al. Standards Track [Page 19] RFC 3744 WebDAV Access Control Protocol May 2004

 >> Response <<
 HTTP/1.1 207 Multi-Status
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxx
 <?xml version="1.0" encoding="utf-8" ?>
 <D:multistatus xmlns:D="DAV:">
   <D:response>
     <D:href>http://www.example.com/papers/</D:href>
     <D:propstat>
       <D:prop>
         <D:supported-privilege-set>
           <D:supported-privilege>
             <D:privilege><D:all/></D:privilege>
            <D:abstract/>
             <D:description xml:lang="en">
               Any operation
             </D:description>
             <D:supported-privilege>
               <D:privilege><D:read/></D:privilege>
               <D:description xml:lang="en">
                 Read any object
               </D:description>
               <D:supported-privilege>
                 <D:privilege><D:read-acl/></D:privilege>
                 <D:abstract/>
                 <D:description xml:lang="en">Read ACL</D:description>
               </D:supported-privilege>
               <D:supported-privilege>
                 <D:privilege>
                   <D:read-current-user-privilege-set/>
                 </D:privilege>
                 <D:abstract/>
                 <D:description xml:lang="en">
                   Read current user privilege set property
                 </D:description>
               </D:supported-privilege>
             </D:supported-privilege>
             <D:supported-privilege>
               <D:privilege><D:write/></D:privilege>
               <D:description xml:lang="en">
                 Write any object
               </D:description>
               <D:supported-privilege>
                 <D:privilege><D:write-acl/></D:privilege>
                 <D:description xml:lang="en">

Clemm, et al. Standards Track [Page 20] RFC 3744 WebDAV Access Control Protocol May 2004

                   Write ACL
                 </D:description>
                 <D:abstract/>
               </D:supported-privilege>
               <D:supported-privilege>
                 <D:privilege><D:write-properties/></D:privilege>
                 <D:description xml:lang="en">
                   Write properties
                 </D:description>
               </D:supported-privilege>
               <D:supported-privilege>
                 <D:privilege><D:write-content/></D:privilege>
                 <D:description xml:lang="en">
                   Write resource content
                 </D:description>
               </D:supported-privilege>
             </D:supported-privilege>
             <D:supported-privilege>
               <D:privilege><D:unlock/></D:privilege>
               <D:description xml:lang="en">
                 Unlock resource
               </D:description>
             </D:supported-privilege>
           </D:supported-privilege>
         </D:supported-privilege-set>
       </D:prop>
       <D:status>HTTP/1.1 200 OK</D:status>
     </D:propstat>
   </D:response>
 </D:multistatus>

5.4. DAV:current-user-privilege-set

 DAV:current-user-privilege-set is a protected property containing the
 exact set of privileges (as computed by the server) granted to the
 currently authenticated HTTP user.  Aggregate privileges and their
 contained privileges are listed.  A user-agent can use the value of
 this property to adjust its user interface to make actions
 inaccessible (e.g., by graying out a menu item or button) for which
 the current principal does not have permission.  This property is
 also useful for determining what operations the current principal can
 perform, without having to actually execute an operation.
 <!ELEMENT current-user-privilege-set (privilege*)>
 <!ELEMENT privilege ANY>

Clemm, et al. Standards Track [Page 21] RFC 3744 WebDAV Access Control Protocol May 2004

 If the current user is granted a specific privilege, that privilege
 must belong to the set of privileges that may be set on this
 resource.  Therefore, each element in the DAV:current-user-
 privilege-set property MUST identify a non-abstract privilege from
 the DAV:supported-privilege-set property.

5.4.1. Example: Retrieving the User's Current Set of Assigned

      Privileges
 Continuing the example from Section 5.3.1, this example shows a
 client requesting the DAV:current-user-privilege-set property from
 the resource with URL http://www.example.com/papers/.  The username
 of the principal making the request is "khare", and Digest
 authentication is used in the request.  The principal with username
 "khare" has been granted the DAV:read privilege.  Since the DAV:read
 privilege contains the DAV:read-acl and DAV:read-current-user-
 privilege-set privileges (see Section 5.3.1), the principal with
 username "khare" can read the ACL property, and the DAV:current-
 user-privilege-set property.  However, the DAV:all, DAV:read-acl,
 DAV:write-acl and DAV:read-current-user-privilege-set privileges are
 not listed in the value of DAV:current-user-privilege-set, since (for
 this example) they are abstract privileges.  DAV:write is not listed
 since the principal with username "khare" is not listed in an ACE
 granting that principal write permission.
 >> Request <<
 PROPFIND /papers/ HTTP/1.1
 Host: www.example.com
 Content-type: text/xml; charset="utf-8"
 Content-Length: xxx
 Depth: 0
 Authorization: Digest username="khare",
   realm="users@example.com", nonce="...",
   uri="/papers/", response="...", opaque="..."
 <?xml version="1.0" encoding="utf-8" ?>
 <D:propfind xmlns:D="DAV:">
   <D:prop>
     <D:current-user-privilege-set/>
   </D:prop>
 </D:propfind>

Clemm, et al. Standards Track [Page 22] RFC 3744 WebDAV Access Control Protocol May 2004

 >> Response <<
 HTTP/1.1 207 Multi-Status
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxx
 <?xml version="1.0" encoding="utf-8" ?>
 <D:multistatus xmlns:D="DAV:">
   <D:response>
   <D:href>http://www.example.com/papers/</D:href>
   <D:propstat>
     <D:prop>
       <D:current-user-privilege-set>
         <D:privilege><D:read/></D:privilege>
       </D:current-user-privilege-set>
     </D:prop>
     <D:status>HTTP/1.1 200 OK</D:status>
   </D:propstat>
   </D:response>
 </D:multistatus>

5.5. DAV:acl

 This is a protected property that specifies the list of access
 control entries (ACEs), which define what principals are to get what
 privileges for this resource.
 <!ELEMENT acl (ace*) >
 Each DAV:ace element specifies the set of privileges to be either
 granted or denied to a single principal.  If the DAV:acl property is
 empty, no principal is granted any privilege.
 <!ELEMENT ace ((principal | invert), (grant|deny), protected?,
                inherited?)>

5.5.1. ACE Principal

 The DAV:principal element identifies the principal to which this ACE
 applies.
 <!ELEMENT principal (href | all | authenticated | unauthenticated
  | property | self)>
 The current user matches DAV:href only if that user is authenticated
 as being (or being a member of) the principal identified by the URL
 contained by that DAV:href.

Clemm, et al. Standards Track [Page 23] RFC 3744 WebDAV Access Control Protocol May 2004

 The current user always matches DAV:all.
 <!ELEMENT all EMPTY>
 The current user matches DAV:authenticated only if authenticated.
 <!ELEMENT authenticated EMPTY>
 The current user matches DAV:unauthenticated only if not
 authenticated.
 <!ELEMENT unauthenticated EMPTY>
 DAV:all is the union of DAV:authenticated, and DAV:unauthenticated.
 For a given request, the user matches either DAV:authenticated, or
 DAV:unauthenticated, but not both (that is, DAV:authenticated and
 DAV:unauthenticated are disjoint sets).
 The current user matches a DAV:property principal in a DAV:acl
 property of a resource only if the value of the identified property
 of that resource contains at most one DAV:href XML element, the URI
 value of DAV:href identifies a principal, and the current user is
 authenticated as being (or being a member of) that principal.  For
 example, if the DAV:property element contained <DAV:owner/>, the
 current user would match the DAV:property principal only if the
 current user is authenticated as matching the principal identified by
 the DAV:owner property of the resource.
 <!ELEMENT property ANY>
 The current user matches DAV:self in a DAV:acl property of the
 resource only if that resource is a principal and that principal
 matches the current user or, if the principal is a group, a member of
 that group matches the current user.
 <!ELEMENT self EMPTY>
 Some servers may support ACEs applying to those users NOT matching
 the current principal, e.g., all users not in a particular group.
 This can be done by wrapping the DAV:principal element with
 DAV:invert.
 <!ELEMENT invert principal>

Clemm, et al. Standards Track [Page 24] RFC 3744 WebDAV Access Control Protocol May 2004

5.5.2. ACE Grant and Deny

 Each DAV:grant or DAV:deny element specifies the set of privileges to
 be either granted or denied to the specified principal.  A DAV:grant
 or DAV:deny element of the DAV:acl of a resource MUST only contain
 non-abstract elements specified in the DAV:supported-privilege-set of
 that resource.
 <!ELEMENT grant (privilege+)>
 <!ELEMENT deny (privilege+)>
 <!ELEMENT privilege ANY>

5.5.3. ACE Protection

 A server indicates an ACE is protected by including the DAV:protected
 element in the ACE.  If the ACL of a resource contains an ACE with a
 DAV:protected element, an attempt to remove that ACE from the ACL
 MUST fail.
 <!ELEMENT protected EMPTY>

5.5.4. ACE Inheritance

 The presence of a DAV:inherited element indicates that this ACE is
 inherited from another resource that is identified by the URL
 contained in a DAV:href element.  An inherited ACE cannot be modified
 directly, but instead the ACL on the resource from which it is
 inherited must be modified.
 Note that ACE inheritance is not the same as ACL initialization.  ACL
 initialization defines the ACL that a newly created resource will use
 (if not specified).  ACE inheritance refers to an ACE that is
 logically shared - where an update to the resource containing an ACE
 will affect the ACE of each resource that inherits that ACE.  The
 method by which ACLs are initialized or by which ACEs are inherited
 is not defined by this document.
 <!ELEMENT inherited (href)>

5.5.5. Example: Retrieving a Resource's Access Control List

 Continuing the example from Sections 5.3.1 and 5.4.1, this example
 shows a client requesting the DAV:acl property from the resource with
 URL http://www.example.com/papers/.  There are two ACEs defined in
 this ACL:

Clemm, et al. Standards Track [Page 25] RFC 3744 WebDAV Access Control Protocol May 2004

 ACE #1: The group identified by URL http://www.example.com/acl/
 groups/maintainers (the group of site maintainers) is granted
 DAV:write privilege.  Since (for this example) DAV:write contains the
 DAV:write-acl privilege (see Section 5.3.1), this means the
 "maintainers" group can also modify the access control list.
 ACE #2: All principals (DAV:all) are granted the DAV:read privilege.
 Since (for this example) DAV:read contains DAV:read-acl and
 DAV:read-current-user-privilege-set, this means all users (including
 all members of the "maintainers" group) can read the DAV:acl property
 and the DAV:current-user-privilege-set property.
 >> Request <<
 PROPFIND /papers/ HTTP/1.1
 Host: www.example.com
 Content-type: text/xml; charset="utf-8"
 Content-Length: xxx
 Depth: 0
 Authorization: Digest username="masinter",
   realm="users@example.com", nonce="...",
   uri="/papers/", response="...", opaque="..."
 <D:propfind xmlns:D="DAV:">
   <D:prop>
     <D:acl/>
   </D:prop>
 </D:propfind>
 >> Response <<
 HTTP/1.1 207 Multi-Status
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxx
 <D:multistatus xmlns:D="DAV:">
   <D:response>
     <D:href>http://www.example.com/papers/</D:href>
     <D:propstat>
       <D:prop>
         <D:acl>
         <D:ace>
           <D:principal>
             <D:href
             >http://www.example.com/acl/groups/maintainers</D:href>
           </D:principal>
           <D:grant>
             <D:privilege><D:write/></D:privilege>

Clemm, et al. Standards Track [Page 26] RFC 3744 WebDAV Access Control Protocol May 2004

           </D:grant>
         </D:ace>
         <D:ace>
           <D:principal>
             <D:all/>
           </D:principal>
           <D:grant>
             <D:privilege><D:read/></D:privilege>
           </D:grant>
         </D:ace>
       </D:acl>
       </D:prop>
       <D:status>HTTP/1.1 200 OK</D:status>
     </D:propstat>
   </D:response>
 </D:multistatus>

5.6. DAV:acl-restrictions

 This protected property defines the types of ACLs supported by this
 server, to avoid clients needlessly getting errors.  When a client
 tries to set an ACL via the ACL method, the server may reject the
 attempt to set the ACL as specified.  The following properties
 indicate the restrictions the client must observe before setting an
 ACL:
 <grant-only> Deny ACEs are not supported
 <no-invert> Inverted ACEs are not supported
 <deny-before-grant> All deny ACEs must occur before any grant ACEs
 <required-principal> Indicates which principals are required to be
    present
 <!ELEMENT acl-restrictions (grant-only?, no-invert?,
                             deny-before-grant?,
                             required-principal?)>

5.6.1. DAV:grant-only

 This element indicates that ACEs with deny clauses are not allowed.
 <!ELEMENT grant-only EMPTY>

Clemm, et al. Standards Track [Page 27] RFC 3744 WebDAV Access Control Protocol May 2004

5.6.2. DAV:no-invert ACE Constraint

 This element indicates that ACEs with the <invert> element are not
 allowed.
 <!ELEMENT no-invert EMPTY>

5.6.3. DAV:deny-before-grant

 This element indicates that all deny ACEs must precede all grant
 ACEs.
 <!ELEMENT deny-before-grant EMPTY>

5.6.4. Required Principals

 The required principal elements identify which principals must have
 an ACE defined in the ACL.
 <!ELEMENT required-principal
   (all? | authenticated? | unauthenticated? | self? | href* |
    property*)>
 For example, the following element requires that the ACL contain a
 DAV:owner property ACE:
 <D:required-principal xmlns:D="DAV:">
   <D:property><D:owner/></D:property>
 </D:required-principal>

5.6.5. Example: Retrieving DAV:acl-restrictions

 In this example, the client requests the value of the DAV:acl-
 restrictions property.  Digest authentication provides credentials
 for the principal operating the client.
 >> Request <<
 PROPFIND /papers/ HTTP/1.1
 Host: www.example.com
 Content-type: text/xml; charset="utf-8"
 Content-Length: xxx
 Depth: 0
 Authorization: Digest username="srcarter",
   realm="users@example.com", nonce="...",
   uri="/papers/", response="...", opaque="..."

Clemm, et al. Standards Track [Page 28] RFC 3744 WebDAV Access Control Protocol May 2004

 <?xml version="1.0" encoding="utf-8" ?>
 <D:propfind xmlns:D="DAV:">
   <D:prop>
     <D:acl-restrictions/>
   </D:prop>
 </D:propfind>
 >> Response <<
 HTTP/1.1 207 Multi-Status
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxx
 <?xml version="1.0" encoding="utf-8" ?>
 <D:multistatus xmlns:D="DAV:">
   <D:response>
     <D:href>http://www.example.com/papers/</D:href>
     <D:propstat>
       <D:prop>
         <D:acl-restrictions>
           <D:grant-only/>
           <D:required-principal>
             <D:all/>
           </D:required-principal>
         </D:acl-restrictions>
       </D:prop>
       <D:status>HTTP/1.1 200 OK</D:status>
     </D:propstat>
   </D:response>
 </D:multistatus>

5.7. DAV:inherited-acl-set

 This protected property contains a set of URLs that identify other
 resources that also control the access to this resource.  To have a
 privilege on a resource, not only must the ACL on that resource
 (specified in the DAV:acl property of that resource) grant the
 privilege, but so must the ACL of each resource identified in the
 DAV:inherited-acl-set property of that resource.  Effectively, the
 privileges granted by the current ACL are ANDed with the privileges
 granted by each inherited ACL.
 <!ELEMENT inherited-acl-set (href*)>

Clemm, et al. Standards Track [Page 29] RFC 3744 WebDAV Access Control Protocol May 2004

5.8. DAV:principal-collection-set

 This protected property of a resource contains a set of URLs that
 identify the root collections that contain the principals that are
 available on the server that implements this resource.  A WebDAV
 Access Control Protocol user agent could use the contents of
 DAV:principal-collection-set to retrieve the DAV:displayname property
 (specified in Section 13.2 of [RFC2518]) of all principals on that
 server, thereby yielding human-readable names for each principal that
 could be displayed in a user interface.
 <!ELEMENT principal-collection-set (href*)>
 Since different servers can control different parts of the URL
 namespace, different resources on the same host MAY have different
 DAV:principal-collection-set values.  The collections specified in
 the DAV:principal-collection-set MAY be located on different hosts
 from the resource. The URLs in DAV:principal-collection-set SHOULD be
 http or https scheme URLs.  For security and scalability reasons, a
 server MAY report only a subset of the entire set of known principal
 collections, and therefore clients should not assume they have
 retrieved an exhaustive listing.  Additionally, a server MAY elect to
 report none of the principal collections it knows about, in which
 case the property value would be empty.
 The value of DAV:principal-collection-set gives the scope of the
 DAV:principal-property-search REPORT (defined in Section 9.4).
 Clients use the DAV:principal-property-search REPORT to populate
 their user interface with a list of principals.  Therefore, servers
 that limit a client's ability to obtain principal information will
 interfere with the client's ability to manipulate access control
 lists, due to the difficulty of getting the URL of a principal for
 use in an ACE.

5.8.1. Example: Retrieving DAV:principal-collection-set

 In this example, the client requests the value of the DAV:principal-
 collection-set property on the collection resource identified by URL
 http://www.example.com/papers/.  The property contains the two URLs,
 http://www.example.com/acl/users/ and http://
 www.example.com/acl/groups/, both wrapped in DAV:href XML elements.
 Digest authentication provides credentials for the principal
 operating the client.

Clemm, et al. Standards Track [Page 30] RFC 3744 WebDAV Access Control Protocol May 2004

 The client might reasonably follow this request with two separate
 PROPFIND requests to retrieve the DAV:displayname property of the
 members of the two collections (/acl/users and /acl/groups).  This
 information could be used when displaying a user interface for
 creating access control entries.
 >> Request <<
 PROPFIND /papers/ HTTP/1.1
 Host: www.example.com
 Content-type: text/xml; charset="utf-8"
 Content-Length: xxx
 Depth: 0
 Authorization: Digest username="yarong",
   realm="users@example.com", nonce="...",
   uri="/papers/", response="...", opaque="..."
 <?xml version="1.0" encoding="utf-8" ?>
 <D:propfind xmlns:D="DAV:">
   <D:prop>
     <D:principal-collection-set/>
   </D:prop>
 </D:propfind>
 >> Response <<
 HTTP/1.1 207 Multi-Status
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxx
 <?xml version="1.0" encoding="utf-8" ?>
 <D:multistatus xmlns:D="DAV:">
   <D:response>
     <D:href>http://www.example.com/papers/</D:href>
     <D:propstat>
       <D:prop>
         <D:principal-collection-set>
           <D:href>http://www.example.com/acl/users/</D:href>
           <D:href>http://www.example.com/acl/groups/</D:href>
         </D:principal-collection-set>
       </D:prop>
     <D:status>HTTP/1.1 200 OK</D:status>
     </D:propstat>
   </D:response>
 </D:multistatus>

Clemm, et al. Standards Track [Page 31] RFC 3744 WebDAV Access Control Protocol May 2004

5.9. Example: PROPFIND to retrieve access control properties

 The following example shows how access control information can be
 retrieved by using the PROPFIND method to fetch the values of the
 DAV:owner, DAV:supported-privilege-set, DAV:current-user-privilege-
 set, and DAV:acl properties.
 >> Request <<
 PROPFIND /top/container/ HTTP/1.1
 Host: www.example.com
 Content-type: text/xml; charset="utf-8"
 Content-Length: xxx
 Depth: 0
 Authorization: Digest username="ejw",
   realm="users@example.com", nonce="...",
   uri="/top/container/", response="...", opaque="..."
 <?xml version="1.0" encoding="utf-8" ?>
 <D:propfind xmlns:D="DAV:">
   <D:prop>
     <D:owner/>
     <D:supported-privilege-set/>
     <D:current-user-privilege-set/>
     <D:acl/>
   </D:prop>
 </D:propfind>
 >> Response <<
 HTTP/1.1 207 Multi-Status
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxx
 <?xml version="1.0" encoding="utf-8" ?>
 <D:multistatus xmlns:D="DAV:"
                xmlns:A="http://www.example.com/acl/">
   <D:response>
     <D:href>http://www.example.com/top/container/</D:href>
     <D:propstat>
       <D:prop>
         <D:owner>
           <D:href>http://www.example.com/users/gclemm</D:href>
         </D:owner>
         <D:supported-privilege-set>
           <D:supported-privilege>
             <D:privilege><D:all/></D:privilege>
             <D:abstract/>

Clemm, et al. Standards Track [Page 32] RFC 3744 WebDAV Access Control Protocol May 2004

             <D:description xml:lang="en">
               Any operation
             </D:description>
             <D:supported-privilege>
               <D:privilege><D:read/></D:privilege>
               <D:description xml:lang="en">
                 Read any object
               </D:description>
             </D:supported-privilege>
             <D:supported-privilege>
               <D:privilege><D:write/></D:privilege>
               <D:abstract/>
               <D:description xml:lang="en">
                 Write any object
               </D:description>
               <D:supported-privilege>
                 <D:privilege><A:create/></D:privilege>
                 <D:description xml:lang="en">
                   Create an object
                 </D:description>
               </D:supported-privilege>
               <D:supported-privilege>
                 <D:privilege><A:update/></D:privilege>
                 <D:description xml:lang="en">
                   Update an object
                 </D:description>
               </D:supported-privilege>
             </D:supported-privilege>
             <D:supported-privilege>
               <D:privilege><A:delete/></D:privilege>
               <D:description xml:lang="en">
                 Delete an object
               </D:description>
             </D:supported-privilege>
             <D:supported-privilege>
               <D:privilege><D:read-acl/></D:privilege>
               <D:description xml:lang="en">
                 Read the ACL
               </D:description>
             </D:supported-privilege>
             <D:supported-privilege>
               <D:privilege><D:write-acl/></D:privilege>
               <D:description xml:lang="en">
                 Write the ACL
               </D:description>
             </D:supported-privilege>
           </D:supported-privilege>
         </D:supported-privilege-set>

Clemm, et al. Standards Track [Page 33] RFC 3744 WebDAV Access Control Protocol May 2004

         <D:current-user-privilege-set>
           <D:privilege><D:read/></D:privilege>
           <D:privilege><D:read-acl/></D:privilege>
         </D:current-user-privilege-set>
         <D:acl>
           <D:ace>
             <D:principal>
               <D:href>http://www.example.com/users/esedlar</D:href>
             </D:principal>
             <D:grant>
               <D:privilege><D:read/></D:privilege>
               <D:privilege><D:write/></D:privilege>
               <D:privilege><D:read-acl/></D:privilege>
             </D:grant>
           </D:ace>
           <D:ace>
             <D:principal>
               <D:href>http://www.example.com/groups/mrktng</D:href>
             </D:principal>
             <D:deny>
               <D:privilege><D:read/></D:privilege>
             </D:deny>
           </D:ace>
           <D:ace>
             <D:principal>
               <D:property><D:owner/></D:property>
             </D:principal>
             <D:grant>
               <D:privilege><D:read-acl/></D:privilege>
               <D:privilege><D:write-acl/></D:privilege>
             </D:grant>
           </D:ace>
           <D:ace>
             <D:principal><D:all/></D:principal>
             <D:grant>
               <D:privilege><D:read/></D:privilege>
             </D:grant>
             <D:inherited>
               <D:href>http://www.example.com/top</D:href>
             </D:inherited>
           </D:ace>
         </D:acl>
       </D:prop>
       <D:status>HTTP/1.1 200 OK</D:status>
     </D:propstat>
   </D:response>
 </D:multistatus>

Clemm, et al. Standards Track [Page 34] RFC 3744 WebDAV Access Control Protocol May 2004

 The value of the DAV:owner property is a single DAV:href XML element
 containing the URL of the principal that owns this resource.
 The value of the DAV:supported-privilege-set property is a tree of
 supported privileges (using "[XML Namespace , localname]" to identify
 each privilege):
 [DAV:, all] (aggregate, abstract)
    |
    +-- [DAV:, read]
    +-- [DAV:, write] (aggregate, abstract)
           |
           +-- [http://www.example.com/acl, create]
           +-- [http://www.example.com/acl, update]
           +-- [http://www.example.com/acl, delete]
    +-- [DAV:, read-acl]
    +-- [DAV:, write-acl]
 The DAV:current-user-privilege-set property contains two privileges,
 DAV:read, and DAV:read-acl.  This indicates that the current
 authenticated user only has the ability to read the resource, and
 read the DAV:acl property on the resource.  The DAV:acl property
 contains a set of four ACEs:
 ACE #1: The principal identified by the URL http://www.example.com/
 users/esedlar is granted the DAV:read, DAV:write, and DAV:read-acl
 privileges.
 ACE #2: The principals identified by the URL http://www.example.com/
 groups/mrktng are denied the DAV:read privilege.  In this example,
 the principal URL identifies a group.
 ACE #3: In this ACE, the principal is a property principal,
 specifically the DAV:owner property.  When evaluating this ACE, the
 value of the DAV:owner property is retrieved, and is examined to see
 if it contains a DAV:href XML element.  If so, the URL within the
 DAV:href element is read, and identifies a principal.  In this ACE,
 the owner is granted DAV:read-acl, and DAV:write-acl privileges.
 ACE #4: This ACE grants the DAV:all principal (all users) the
 DAV:read privilege.  This ACE is inherited from the resource http://
 www.example.com/top, the parent collection of this resource.

Clemm, et al. Standards Track [Page 35] RFC 3744 WebDAV Access Control Protocol May 2004

6. ACL Evaluation

 WebDAV ACLs are evaluated in similar manner as ACLs on Windows NT and
 in NFSv4 [RFC3530]).  An ACL is evaluated to determine whether or not
 access will be granted for a WebDAV request.  ACEs are maintained in
 a particular order, and are evaluated until all of the permissions
 required by the current request have been granted, at which point the
 ACL evaluation is terminated and access is granted.  If, during ACL
 evaluation, a <deny> ACE (matching the current user) is encountered
 for a privilege which has not yet been granted, the ACL evaluation is
 terminated and access is denied.  Failure to have all required
 privileges granted results in access being denied.
 Note that the semantics of many other existing ACL systems may be
 represented via this mechanism, by mixing deny and grant ACEs.  For
 example, consider the standard "rwx" privilege scheme used by UNIX.
 In this scheme, if the current user is the owner of the file, access
 is granted if the corresponding privilege bit is set and denied if
 not set, regardless of the permissions set on the file's group and
 for the world.  An ACL for UNIX permissions of "r--rw-r--" might be
 constructed like:
 <D:acl>
   <D:ace>
     <D:principal>
       <D:property><D:owner/></D:property>
     </D:principal>
     <D:grant>
       <D:privilege><D:read/></D:privilege>
     </D:grant>
   </D:ace>
   <D:ace>
     <D:principal>
       <D:property><D:owner/></D:property>
     </D:principal>
     <D:deny>
       <D:privilege><D:all/></D:privilege>
     </D:deny>
   </D:ace>
   <D:ace>
     <D:principal>
       <D:property><D:group/></D:property>
     </D:principal>
     <D:grant>
       <D:privilege><D:read/></D:privilege>
       <D:privilege><D:write/></D:privilege>
     </D:grant>
   </D:ace>

Clemm, et al. Standards Track [Page 36] RFC 3744 WebDAV Access Control Protocol May 2004

   <D:ace>
     <D:principal>
       <D:property><D:group/></D:property>
     </D:principal>
     <D:deny>
       <D:privilege><D:all/></D:privilege>
     </D:deny>
   </D:ace>
   <D:ace>
     <D:principal><D:all></D:principal>
     <D:grant>
       <D:privilege><D:read/></D:privilege>
     </D:grant>
   </D:ace>
 </D:acl>
 and the <acl-restrictions> would be defined as:
 <D:no-invert/>
 <D:required-principal>
   <D:all/>
   <D:property><D:owner/></D:property>
   <D:property><D:group/><D:group/>
 </D:required-principal>
 Note that the client can still get errors from a UNIX server in spite
 of obeying the <acl-restrictions>, including <D:allowed-principal>
 (adding an ACE specifying a principal other than the ones in the ACL
 above) or <D:ace-conflict> (by trying to reorder the ACEs in the
 example above), as these particular implementation semantics are too
 complex to be captured with the simple (but general) declarative
 restrictions.

7. Access Control and existing methods

 This section defines the impact of access control functionality on
 existing methods.

7.1. Any HTTP method

7.1.1. Error Handling

 The WebDAV ACL mechanism requires the usage of HTTP method
 "preconditions" as described in section 1.6 of RFC3253 for ALL HTTP
 methods.  All HTTP methods have an additional precondition called
 DAV:need-privileges.  If an HTTP method fails due to insufficient
 privileges, the response body to the "403 Forbidden" error MUST
 contain the <DAV:error> element, which in turn contains the

Clemm, et al. Standards Track [Page 37] RFC 3744 WebDAV Access Control Protocol May 2004

 <DAV:need-privileges> element, which contains one or more
 <DAV:resource> elements indicating which resource had insufficient
 privileges, and what the lacking privileges were:
 <!ELEMENT need-privileges (resource)* >
 <!ELEMENT resource ( href , privilege ) >
 Since some methods require multiple permissions on multiple
 resources, this information is needed to resolve any ambiguity.
 There is no requirement that all privilege violations be reported -
 for implementation reasons, some servers may only report the first
 privilege violation.  For example:
 >> Request <<
 MOVE /a/b/ HTTP/1.1
 Host: www.example.com
 Destination: http://www.example.com/c/d
 >> Response <<
 HTTP/1.1 403 Forbidden
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxx
 <D:error xmlns:D="DAV:">
   <D:need-privileges>
     <D:resource>
       <D:href>/a</D:href>
       <D:privilege><D:unbind/></D:privilege>
     </D:resource>
     <D:resource>
       <D:href>/c</D:href>
       <D:privilege><D:bind/></D:privilege>
     </D:resource>
   </D:need-privileges>
 </D:error>

7.2. OPTIONS

 If the server supports access control, it MUST return "access-
 control" as a field in the DAV response header from an OPTIONS
 request on any resource implemented by that server.  A value of
 "access-control" in the DAV header MUST indicate that the server
 supports all MUST level requirements and REQUIRED features specified
 in this document.

Clemm, et al. Standards Track [Page 38] RFC 3744 WebDAV Access Control Protocol May 2004

7.2.1. Example - OPTIONS

 >> Request <<
 OPTIONS /foo.html HTTP/1.1
 Host: www.example.com
 Content-Length: 0
 >> Response <<
 HTTP/1.1 200 OK
 DAV: 1, 2, access-control
 Allow: OPTIONS, GET, PUT, PROPFIND, PROPPATCH, ACL
 In this example, the OPTIONS response indicates that the server
 supports access control and that /foo.html can have its access
 control list modified by the ACL method.

7.3. MOVE

 When a resource is moved from one location to another due to a MOVE
 request, the non-inherited and non-protected ACEs in the DAV:acl
 property of the resource MUST NOT be modified, or the MOVE request
 fails.  Handling of inherited and protected ACEs is intentionally
 undefined to give server implementations flexibility in how they
 implement ACE inheritance and protection.

7.4. COPY

 The DAV:acl property on the resource at the destination of a COPY
 MUST be the same as if the resource was created by an individual
 resource creation request (e.g., MKCOL, PUT).  Clients wishing to
 preserve the DAV:acl property across a copy need to read the DAV:acl
 property prior to the COPY, then perform an ACL operation on the new
 resource at the destination to restore, insofar as this is possible,
 the original access control list.

7.5. LOCK

 A lock on a resource ensures that only the lock owner can modify ACEs
 that are not inherited and not protected  (these are the only ACEs
 that a client can modify with an ACL request).  A lock does not
 protect inherited or protected ACEs, since a client cannot modify
 them with an ACL request on that resource.

Clemm, et al. Standards Track [Page 39] RFC 3744 WebDAV Access Control Protocol May 2004

8. Access Control Methods

8.1. ACL

 The ACL method modifies the access control list (which can be read
 via the DAV:acl property) of a resource.  Specifically, the ACL
 method only permits modification to ACEs that are not inherited, and
 are not protected.  An ACL method invocation modifies all non-
 inherited and non-protected ACEs in a resource's access control list
 to exactly match the ACEs contained within in the DAV:acl XML element
 (specified in Section 5.5) of the request body.  An ACL request body
 MUST contain only one DAV:acl XML element.  Unless the non-inherited
 and non-protected ACEs of the DAV:acl property of the resource can be
 updated to be exactly the value specified in the ACL request, the ACL
 request MUST fail.
 It is possible that the ACEs visible to the current user in the
 DAV:acl property may only be a portion of the complete set of ACEs on
 that resource.  If this is the case, an ACL request only modifies the
 set of ACEs visible to the current user, and does not affect any
 non-visible ACE.
 In order to avoid overwriting DAV:acl changes by another client, a
 client SHOULD acquire a WebDAV lock on the resource before retrieving
 the DAV:acl property of a resource that it intends on updating.
    Implementation Note: Two common operations are to add or remove an
    ACE from an existing access control list.  To accomplish this, a
    client uses the PROPFIND method to retrieve the value of the
    DAV:acl property, then parses the returned access control list to
    remove all inherited and protected ACEs (these ACEs are tagged
    with the DAV:inherited and DAV:protected XML elements).  In the
    remaining set of non-inherited, non-protected ACEs, the client can
    add or remove one or more ACEs before submitting the final ACE set
    in the request body of the ACL method.

8.1.1. ACL Preconditions

 An implementation MUST enforce the following constraints on an ACL
 request.  If the constraint is violated, a 403 (Forbidden) or 409
 (Conflict) response MUST be returned and the indicated XML element
 MUST be returned as a child of a top level DAV:error element in an
 XML response body.
 Though these status elements are generally expressed as empty XML
 elements (and are defined as EMPTY in the DTD), implementations MAY
 return additional descriptive XML elements as children of the status

Clemm, et al. Standards Track [Page 40] RFC 3744 WebDAV Access Control Protocol May 2004

 element.  Clients MUST be able to accept children of these status
 elements.  Clients that do not understand the additional XML elements
 should ignore them.
 (DAV:no-ace-conflict): The ACEs submitted in the ACL request MUST NOT
 conflict with each other.  This is a catchall error code indicating
 that an implementation-specific ACL restriction has been violated.
 (DAV:no-protected-ace-conflict): The ACEs submitted in the ACL
 request MUST NOT conflict with the protected ACEs on the resource.
 For example, if the resource has a protected ACE granting DAV:write
 to a given principal, then it would not be consistent if the ACL
 request submitted an ACE denying DAV:write to the same principal.
 (DAV:no-inherited-ace-conflict): The ACEs submitted in the ACL
 request MUST NOT conflict with the inherited ACEs on the resource.
 For example, if the resource inherits an ACE from its parent
 collection granting DAV:write to a given principal, then it would not
 be consistent if the ACL request submitted an ACE denying DAV:write
 to the same principal.  Note that reporting of this error will be
 implementation-dependent.  Implementations MUST either report this
 error or allow the ACE to be set, and then let normal ACE evaluation
 rules determine whether the new ACE has any impact on the privileges
 available to a specific principal.
 (DAV:limited-number-of-aces): The number of ACEs submitted in the ACL
 request MUST NOT exceed the number of ACEs allowed on that resource.
 However, ACL-compliant servers MUST support at least one ACE granting
 privileges to a single principal, and one ACE granting privileges to
 a group.
 (DAV:deny-before-grant): All non-inherited deny ACEs MUST precede all
 non-inherited grant ACEs.
 (DAV:grant-only): The ACEs submitted in the ACL request MUST NOT
 include a deny ACE.  This precondition applies only when the ACL
 restrictions of the resource include the DAV:grant-only constraint
 (defined in Section 5.6.1).
 (DAV:no-invert):  The ACL request MUST NOT include a DAV:invert
 element.  This precondition applies only when the ACL semantics of
 the resource includes the DAV:no-invert constraint (defined in
 Section 5.6.2).
 (DAV:no-abstract): The ACL request MUST NOT attempt to grant or deny
 an abstract privilege (see Section 5.3).

Clemm, et al. Standards Track [Page 41] RFC 3744 WebDAV Access Control Protocol May 2004

 (DAV:not-supported-privilege): The ACEs submitted in the ACL request
 MUST be supported by the resource.
 (DAV:missing-required-principal): The result of the ACL request MUST
 have at least one ACE for each principal identified in a
 DAV:required-principal XML element in the ACL semantics of that
 resource (see Section 5.5).
 (DAV:recognized-principal): Every principal URL in the ACL request
 MUST identify a principal resource.
 (DAV:allowed-principal): The principals specified in the ACEs
 submitted in the ACL request MUST be allowed as principals for the
 resource.  For example, a server where only authenticated principals
 can access resources would not allow the DAV:all or
 DAV:unauthenticated principals to be used in an ACE, since these
 would allow unauthenticated access to resources.

8.1.2. Example: the ACL method

 In the following example, user "fielding", authenticated by
 information in the Authorization header, grants the principal
 identified by the URL http://www.example.com/users/esedlar (i.e., the
 user "esedlar") read and write privileges, grants the owner of the
 resource read-acl and write-acl privileges, and grants everyone read
 privileges.
 >> Request <<
 ACL /top/container/ HTTP/1.1
 Host: www.example.com
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxxx
 Authorization: Digest username="fielding",
   realm="users@example.com", nonce="...",
   uri="/top/container/", response="...", opaque="..."
 <?xml version="1.0" encoding="utf-8" ?>
 <D:acl xmlns:D="DAV:">
   <D:ace>
     <D:principal>
       <D:href>http://www.example.com/users/esedlar</D:href>
     </D:principal>
     <D:grant>
       <D:privilege><D:read/></D:privilege>
       <D:privilege><D:write/></D:privilege>
     </D:grant>
   </D:ace>

Clemm, et al. Standards Track [Page 42] RFC 3744 WebDAV Access Control Protocol May 2004

   <D:ace>
     <D:principal>
       <D:property><D:owner/></D:property>
     </D:principal>
     <D:grant>
       <D:privilege><D:read-acl/></D:privilege>
       <D:privilege><D:write-acl/></D:privilege>
     </D:grant>
   </D:ace>
   <D:ace>
     <D:principal><D:all/></D:principal>
     <D:grant>
       <D:privilege><D:read/></D:privilege>
     </D:grant>
   </D:ace>
 </D:acl>
 >> Response <<
 HTTP/1.1 200 OK

8.1.3. Example: ACL method failure due to protected ACE conflict

 In the following request, user "fielding", authenticated by
 information in the Authorization header, attempts to deny the
 principal identified by the URL http://www.example.com/users/esedlar
 (i.e., the user "esedlar") write privileges.  Prior to the request,
 the DAV:acl property on the resource contained a protected ACE (see
 Section 5.5.3) granting DAV:owner the DAV:read and DAV:write
 privileges.  The principal identified by URL http://www.example.com/
 users/esedlar is the owner of the resource.  The ACL method
 invocation fails because the submitted ACE conflicts with the
 protected ACE, thus violating the semantics of ACE protection.
 >> Request <<
 ACL /top/container/ HTTP/1.1
 Host: www.example.com
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxxx
 Authorization: Digest username="fielding",
   realm="users@example.com", nonce="...",
   uri="/top/container/", response="...", opaque="..."
 <?xml version="1.0" encoding="utf-8" ?>
 <D:acl xmlns:D="DAV:">
   <D:ace>
     <D:principal>

Clemm, et al. Standards Track [Page 43] RFC 3744 WebDAV Access Control Protocol May 2004

       <D:href>http://www.example.com/users/esedlar</D:href>
     </D:principal>
     <D:deny>
       <D:privilege><D:write/></D:privilege>
     </D:deny>
   </D:ace>
 </D:acl>
 >> Response <<
 HTTP/1.1 403 Forbidden
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxx
 <?xml version="1.0" encoding="utf-8" ?>
 <D:error xmlns:D="DAV:">
   <D:no-protected-ace-conflict/>
 </D:error>

8.1.4. Example: ACL method failure due to an inherited ACE conflict

 In the following request, user "ejw", authenticated by information in
 the Authorization header, tries to change the access control list on
 the resource http://www.example.com/top/index.html.  This resource
 has two inherited ACEs.
 Inherited ACE #1 grants the principal identified by URL http://
 www.example.com/users/ejw (i.e., the user "ejw") http://
 www.example.com/privs/write-all and DAV:read-acl privileges.  On this
 server, http://www.example.com/privs/write-all is an aggregate
 privilege containing DAV:write, and DAV:write-acl.
 Inherited ACE #2 grants principal DAV:all the DAV:read privilege.
 The request attempts to set a (non-inherited) ACE, denying the
 principal identified by the URL http://www.example.com/users/ejw
 (i.e., the user "ejw") DAV:write permission.  This conflicts with
 inherited ACE #1.  Note that the decision to report an inherited ACE
 conflict is specific to this server implementation.  Another server
 implementation could have allowed the new ACE to be set, and then
 used normal ACE evaluation rules to determine whether the new ACE has
 any impact on the privileges available to a principal.

Clemm, et al. Standards Track [Page 44] RFC 3744 WebDAV Access Control Protocol May 2004

 >> Request <<
 ACL /top/index.html HTTP/1.1
 Host: www.example.com
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxxx
 Authorization: Digest username="ejw",
   realm="users@example.com", nonce="...",
   uri="/top/index.html", response="...", opaque="..."
 <?xml version="1.0" encoding="utf-8" ?>
 <D:acl xmlns:D="DAV:" xmlns:F="http://www.example.com/privs/">
   <D:ace>
     <D:principal>
        <D:href>http://www.example.com/users/ejw</D:href>
     </D:principal>
     <D:grant><D:write/></D:grant>
   </D:ace>
 </D:acl>
 >> Response <<
 HTTP/1.1 403 Forbidden
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxx
 <?xml version="1.0" encoding="utf-8" ?>
 <D:error xmlns:D="DAV:">
   <D:no-inherited-ace-conflict/>
 </D:error>

8.1.5. Example: ACL method failure due to an attempt to set grant and

      deny in a single ACE
 In this example, user "ygoland", authenticated by information in the
 Authorization header, tries to change the access control list on the
 resource http://www.example.com/diamond/engagement-ring.gif.  The ACL
 request includes a single, syntactically and semantically incorrect
 ACE, which attempts to grant the group identified by the URL http://
 www.example.com/users/friends DAV:read privilege and deny the
 principal identified by URL http://www.example.com/users/ygoland-so
 (i.e., the user "ygoland-so") DAV:read privilege.  However, it is
 illegal to have multiple principal elements, as well as both a grant
 and deny element in the same ACE, so the request fails due to poor
 syntax.

Clemm, et al. Standards Track [Page 45] RFC 3744 WebDAV Access Control Protocol May 2004

 >> Request <<
 ACL /diamond/engagement-ring.gif HTTP/1.1
 Host: www.example.com
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxxx
 Authorization: Digest username="ygoland",
   realm="users@example.com", nonce="...",
   uri="/diamond/engagement-ring.gif", response="...",
   opaque="..."
 <?xml version="1.0" encoding="utf-8" ?>
 <D:acl xmlns:D="DAV:">
   <D:ace>
     <D:principal>
       <D:href>http://www.example.com/users/friends</D:href>
     </D:principal>
     <D:grant><D:read/></D:grant>
     <D:principal>
       <D:href>http://www.example.com/users/ygoland-so</D:href>
     </D:principal>
     <D:deny><D:read/></D:deny>
   </D:ace>
 </D:acl>
 >> Response <<
 HTTP/1.1 400 Bad Request
 Content-Length: 0
 Note that if the request had been divided into two ACEs, one to
 grant, and one to deny, the request would have been syntactically
 well formed.

9. Access Control Reports

9.1. REPORT Method

 The REPORT method (defined in Section 3.6 of [RFC3253]) provides an
 extensible mechanism for obtaining information about a resource.
 Unlike the PROPFIND method, which returns the value of one or more
 named properties, the REPORT method can involve more complex
 processing.  REPORT is valuable in cases where the server has access
 to all of the information needed to perform the complex request (such
 as a query), and where it would require multiple requests for the
 client to retrieve the information needed to perform the same
 request.

Clemm, et al. Standards Track [Page 46] RFC 3744 WebDAV Access Control Protocol May 2004

 A server that supports the WebDAV Access Control Protocol MUST
 support the DAV:expand-property report (defined in Section 3.8 of
 [RFC3253]).

9.2. DAV:acl-principal-prop-set Report

 The DAV:acl-principal-prop-set report returns, for all principals in
 the DAV:acl property (of the Request-URI) that are identified by
 http(s) URLs or by a DAV:property principal, the value of the
 properties specified in the REPORT request body.  In the case where a
 principal URL appears multiple times, the DAV:acl-principal-prop-set
 report MUST return the properties for that principal only once.
 Support for this report is REQUIRED.
 One expected use of this report is to retrieve the human readable
 name (found in the DAV:displayname property) of each principal found
 in an ACL.  This is useful for constructing user interfaces that show
 each ACE in a human readable form.
 Marshalling
    The request body MUST be a DAV:acl-principal-prop-set XML element.
    <!ELEMENT acl-principal-prop-set ANY>
    ANY value: a sequence of one or more elements, with at most one
               DAV:prop element.
    prop: see RFC 2518, Section 12.11
    This report is only defined when the Depth header has value "0";
    other values result in a 400 (Bad Request) error response.  Note
    that [RFC3253], Section 3.6, states that if the Depth header is
    not present, it defaults to a value of "0".
    The response body for a successful request MUST be a
    DAV:multistatus XML element (i.e., the response uses the same
    format as the response for PROPFIND).  In the case where there are
    no response elements, the returned multistatus XML element is
    empty.
    multistatus: see RFC 2518, Section 12.9
    The response body for a successful DAV:acl-principal-prop-set
    REPORT request MUST contain a DAV:response element for each
    principal identified by an http(s) URL listed in a DAV:principal
    XML element of an ACE within the DAV:acl property of the resource
    identified by the Request-URI.

Clemm, et al. Standards Track [Page 47] RFC 3744 WebDAV Access Control Protocol May 2004

 Postconditions:
    (DAV:number-of-matches-within-limits): The number of matching
    principals must fall within server-specific, predefined limits.
    For example, this condition might be triggered if a search
    specification would cause the return of an extremely large number
    of responses.

9.2.1. Example: DAV:acl-principal-prop-set Report

 Resource http://www.example.com/index.html has an ACL with three
 ACEs:
 ACE #1: All principals (DAV:all) have DAV:read and DAV:read-current-
 user-privilege-set access.
 ACE #2: The principal identified by http://www.example.com/people/
 gstein (the user "gstein") is granted DAV:write,  DAV:write-acl,
 DAV:read-acl privileges.
 ACE #3: The group identified by http://www.example.com/groups/authors
 (the "authors" group) is granted DAV:write and DAV:read-acl
 privileges.
 The following example shows a DAV:acl-principal-prop-set report
 requesting the DAV:displayname property.  It returns the value of
 DAV:displayname for resources http://www.example.com/people/gstein
 and http://www.example.com/groups/authors , but not for DAV:all,
 since this is not an http(s) URL.
 >> Request <<
 REPORT /index.html HTTP/1.1
 Host: www.example.com
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxxx
 Depth: 0
 <?xml version="1.0" encoding="utf-8" ?>
 <D:acl-principal-prop-set xmlns:D="DAV:">
   <D:prop>
     <D:displayname/>
   </D:prop>
 </D:acl-principal-prop-set>

Clemm, et al. Standards Track [Page 48] RFC 3744 WebDAV Access Control Protocol May 2004

 >> Response <<
 HTTP/1.1 207 Multi-Status
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxxx
 <?xml version="1.0" encoding="utf-8" ?>
 <D:multistatus xmlns:D="DAV:">
   <D:response>
     <D:href>http://www.example.com/people/gstein</D:href>
     <D:propstat>
       <D:prop>
         <D:displayname>Greg Stein</D:displayname>
       </D:prop>
       <D:status>HTTP/1.1 200 OK</D:status>
     </D:propstat>
   </D:response>
   <D:response>
     <D:href>http://www.example.com/groups/authors</D:href>
     <D:propstat>
       <D:prop>
         <D:displayname>Site authors</D:displayname>
       </D:prop>
       <D:status>HTTP/1.1 200 OK</D:status>
     </D:propstat>
   </D:response>
 </D:multistatus>

9.3. DAV:principal-match REPORT

 The DAV:principal-match REPORT is used to identify all members (at
 any depth) of the collection identified by the Request-URI that are
 principals and that match the current user.  In particular, if the
 collection contains principals, the report can be used to identify
 all members of the collection that match the current user.
 Alternatively, if the collection contains resources that have a
 property that identifies a principal (e.g., DAV:owner), the report
 can be used to identify all members of the collection whose property
 identifies a principal that matches the current user.  For example,
 this report can return all of the resources in a collection hierarchy
 that are owned by the current user.  Support for this report is
 REQUIRED.
 Marshalling:
    The request body MUST be a DAV:principal-match XML element.
    <!ELEMENT principal-match ((principal-property | self), prop?)>
    <!ELEMENT principal-property ANY>

Clemm, et al. Standards Track [Page 49] RFC 3744 WebDAV Access Control Protocol May 2004

    ANY value: an element whose value identifies a property.  The
    expectation is the value of the named property typically contains
    an href element that contains the URI of a principal
    <!ELEMENT self EMPTY>
    prop: see RFC 2518, Section 12.11
    This report is only defined when the Depth header has value "0";
    other values result in a 400 (Bad Request) error response.  Note
    that [RFC3253], Section 3.6, states that if the Depth header is
    not present, it defaults to a value of "0".  The response body for
    a successful request MUST be a DAV:multistatus XML element.  In
    the case where there are no response elements, the returned
    multistatus XML element is empty.
    multistatus: see RFC 2518, Section 12.9
    The response body for a successful DAV:principal-match REPORT
    request MUST contain a DAV:response element for each member of the
    collection that matches the current user.  When the
    DAV:principal-property element is used, a match occurs if the
    current user is matched by the principal identified by the URI
    found in the DAV:href element of the property identified by the
    DAV:principal-property element.  When the DAV:self element is used
    in a DAV:principal-match report issued against a group, it matches
    the group if a member identifies the same principal as the current
    user.
    If DAV:prop is specified in the request body, the properties
    specified in the DAV:prop element MUST be reported in the
    DAV:response elements.

9.3.1. Example: DAV:principal-match REPORT

 The following example identifies the members of the collection
 identified by the URL http://www.example.com/doc that are owned by
 the current user.  The current user ("gclemm") is authenticated using
 Digest authentication.
 >> Request <<
 REPORT /doc/ HTTP/1.1
 Host: www.example.com
 Authorization: Digest username="gclemm",
   realm="users@example.com", nonce="...",
   uri="/papers/", response="...", opaque="..."
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxxx
 Depth: 0

Clemm, et al. Standards Track [Page 50] RFC 3744 WebDAV Access Control Protocol May 2004

 <?xml version="1.0" encoding="utf-8" ?>
 <D:principal-match xmlns:D="DAV:">
   <D:principal-property>
     <D:owner/>
   </D:principal-property>
 </D:principal-match>
 >> Response <<
 HTTP/1.1 207 Multi-Status
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxxx
 <?xml version="1.0" encoding="utf-8" ?>
 <D:multistatus xmlns:D="DAV:">
   <D:response>
     <D:href>http://www.example.com/doc/foo.html</D:href>
     <D:status>HTTP/1.1 200 OK</D:status>
   </D:response>
   <D:response>
     <D:href>http://www.example.com/doc/img/bar.gif</D:href>
     <D:status>HTTP/1.1 200 OK</D:status>
   </D:response>
 </D:multistatus>

9.4. DAV:principal-property-search REPORT

 The DAV:principal-property-search REPORT performs a search for all
 principals whose properties contain character data that matches the
 search criteria specified in the request.  One expected use of this
 report is to discover the URL of a principal associated with a given
 person or group by searching for them by name.  This is done by
 searching over DAV:displayname, which is defined on all principals.
 The actual search method (exact matching vs. substring matching vs,
 prefix-matching, case-sensitivity) deliberately is left to the server
 implementation to allow implementation on a wide set of possible user
 management systems.  In cases where the implementation of
 DAV:principal-property-search is not constrained by the semantics of
 an underlying user management repository, preferred default semantics
 are caseless substring matches.
 For implementation efficiency, servers do not typically support
 searching on all properties.  A search requesting properties that are
 not searchable for a particular principal will not match that
 principal.
 Support for the DAV:principal-property-search report is REQUIRED.

Clemm, et al. Standards Track [Page 51] RFC 3744 WebDAV Access Control Protocol May 2004

    Implementation Note: The value of a WebDAV property is a sequence
    of well-formed XML, and hence can include any character in the
    Unicode/ISO-10646 standard, that is, most known characters in
    human languages.  Due to the idiosyncrasies of case mapping across
    human languages, implementation of case-insensitive matching is
    non-trivial.  Implementors of servers that do perform substring
    matching are strongly encouraged to consult "The Unicode Standard"
    [UNICODE4], especially Section 5.18, Subsection "Caseless
    Matching", for guidance when implementing their case-insensitive
    matching algorithms.
    Implementation Note: Some implementations of this protocol will
    use an LDAP repository for storage of principal metadata.  The
    schema describing each attribute (akin to a WebDAV property) in an
    LDAP repository specifies whether it supports case-sensitive or
    caseless searching.  One of the benefits of leaving the search
    method to the discretion of the server implementation is the
    default LDAP attribute search behavior can be used when
    implementing the DAV:principal-property-search report.
 Marshalling:
    The request body MUST be a DAV:principal-property-search XML
    element containing a search specification and an optional list of
    properties.  For every principal that matches the search
    specification, the response will contain the value of the
    requested properties on that principal.
    <!ELEMENT principal-property-search
     ((property-search+), prop?, apply-to-principal-collection-set?) >
    By default, the report searches all members (at any depth) of the
    collection identified by the Request-URI.  If DAV:apply-to-
    principal-collection-set is specified in the request body, the
    request is applied instead to each collection identified by the
    DAV:principal-collection-set property of the resource identified
    by the Request-URI.
    The DAV:property-search element contains a prop element
    enumerating the properties to be searched and a match element,
    containing the search string.
    <!ELEMENT property-search (prop, match) >
    prop: see RFC 2518, Section 12.11
    <!ELEMENT match #PCDATA >

Clemm, et al. Standards Track [Page 52] RFC 3744 WebDAV Access Control Protocol May 2004

    Multiple property-search elements or multiple elements within a
    DAV:prop element will be interpreted with a logical AND.
    This report is only defined when the Depth header has value "0";
    other values result in a 400 (Bad Request) error response.  Note
    that [RFC3253], Section 3.6, states that if the Depth header is
    not present, it defaults to a value of "0".
    The response body for a successful request MUST be a
    DAV:multistatus XML element.  In the case where there are no
    response elements, the returned multistatus XML element is empty.
    multistatus: see RFC 2518, Section 12.9
    The response body for a successful DAV:principal-property-search
    REPORT request MUST contain  a DAV:response element for each
    principal whose property values satisfy the search specification
    given in DAV:principal-property-search.
    If DAV:prop is specified in the request body, the properties
    specified in the DAV:prop element MUST be reported in the
    DAV:response elements.
 Preconditions:
    None
 Postconditions:
    (DAV:number-of-matches-within-limits): The number of matching
    principals must fall within server-specific, predefined limits.
    For example, this condition might be triggered if a search
    specification would cause the return of an extremely large number
    of responses.

9.4.1. Matching

 There are several cases to consider when matching strings.  The
 easiest case is when a property value is "simple" and has only
 character information item content (see [REC-XML-INFOSET]).  For
 example, the search string "julian" would match the DAV:displayname
 property with value "Julian Reschke".  Note that the on-the-wire
 marshaling of DAV:displayname in this case is:
 <D:displayname xmlns:D="DAV:">Julian Reschke</D:displayname>

Clemm, et al. Standards Track [Page 53] RFC 3744 WebDAV Access Control Protocol May 2004

 The name of the property is encoded into the XML element information
 item, and the character information item content of the property is
 "Julian Reschke".
 A more complicated case occurs when properties have mixed content
 (that is, compound values consisting of multiple child element items,
 other types of information items, and character information item
 content).  Consider the property "aprop" in the namespace "http://
 www.example.com/props/", marshaled as:
 <W:aprop xmlns:W="http://www.example.com/props/">
   {cdata 0}<W:elem1>{cdata 1}</W:elem1>
   <W:elem2>{cdata 2}</W:elem2>{cdata 3}
 </W:aprop>
 In this case, matching is performed on each individual contiguous
 sequence of character information items.  In the example above, a
 search string would be compared to the four following strings:
 {cdata 0}
 {cdata 1}
 {cdata 2}
 {cdata 3}
 That is, four individual matches would be performed, one each for
 {cdata 0}, {cdata 1}, {cdata 2}, and {cdata 3}.

9.4.2. Example: successful DAV:principal-property-search REPORT

 In this example, the client requests the principal URLs of all users
 whose DAV:displayname property contains the substring "doE" and whose
 "title" property in the namespace "http://BigCorp.com/ns/" (that is,
 their professional title) contains "Sales".  In addition, the client
 requests five properties to be returned with the matching principals:
 In the DAV: namespace: displayname
 In the http://www.example.com/ns/ namespace: department, phone,
 office, salary

Clemm, et al. Standards Track [Page 54] RFC 3744 WebDAV Access Control Protocol May 2004

 The response shows that two principal resources meet the search
 specification, "John Doe" and "Zygdoebert Smith".  The property
 "salary" in namespace "http://www.example.com/ns/" is not returned,
 since the principal making the request does not have sufficient
 access permissions to read this property.
 >> Request <<
 REPORT /users/ HTTP/1.1
 Host: www.example.com
 Content-Type: text/xml; charset=utf-8
 Content-Length: xxxx
 Depth: 0
 <?xml version="1.0" encoding="utf-8" ?>
 <D:principal-property-search xmlns:D="DAV:">
   <D:property-search>
     <D:prop>
       <D:displayname/>
     </D:prop>
     <D:match>doE</D:match>
   </D:property-search>
   <D:property-search>
     <D:prop xmlns:B="http://www.example.com/ns/">
       <B:title/>
     </D:prop>
     <D:match>Sales</D:match>
   </D:property-search>
   <D:prop xmlns:B="http://www.example.com/ns/">
     <D:displayname/>
     <B:department/>
     <B:phone/>
     <B:office/>
     <B:salary/>
   </D:prop>
 </D:principal-property-search>
 >> Response <<
 HTTP/1.1 207 Multi-Status
 Content-Type: text/xml; charset=utf-8
 Content-Length: xxxx
 <?xml version="1.0" encoding="utf-8" ?>
 <D:multistatus xmlns:D="DAV:" xmlns:B="http://BigCorp.com/ns/">
   <D:response>
     <D:href>http://www.example.com/users/jdoe</D:href>
     <D:propstat>

Clemm, et al. Standards Track [Page 55] RFC 3744 WebDAV Access Control Protocol May 2004

       <D:prop>
         <D:displayname>John Doe</D:displayname>
         <B:department>Widget Sales</B:department>
         <B:phone>234-4567</B:phone>
         <B:office>209</B:office>
       </D:prop>
       <D:status>HTTP/1.1 200 OK</D:status>
     </D:propstat>
     <D:propstat>
       <D:prop>
         <B:salary/>
       </D:prop>
       <D:status>HTTP/1.1 403 Forbidden</D:status>
     </D:propstat>
   </D:response>
   <D:response>
     <D:href>http://www.example.com/users/zsmith</D:href>
     <D:propstat>
       <D:prop>
         <D:displayname>Zygdoebert Smith</D:displayname>
         <B:department>Gadget Sales</B:department>
         <B:phone>234-7654</B:phone>
         <B:office>114</B:office>
       </D:prop>
       <D:status>HTTP/1.1 200 OK</D:status>
     </D:propstat>
     <D:propstat>
       <D:prop>
         <B:salary/>
       </D:prop>
       <D:status>HTTP/1.1 403 Forbidden</D:status>
     </D:propstat>
   </D:response>
 </D:multistatus>

9.5. DAV:principal-search-property-set REPORT

 The DAV:principal-search-property-set REPORT identifies those
 properties that may be searched using the DAV:principal-property-
 search REPORT (defined in Section 9.4).
 Servers MUST support the DAV:principal-search-property-set REPORT on
 all collections identified in the value of a DAV:principal-
 collection-set property.
 An access control protocol user agent could use the results of the
 DAV:principal-search-property-set REPORT to present a query interface
 to the user for retrieving principals.

Clemm, et al. Standards Track [Page 56] RFC 3744 WebDAV Access Control Protocol May 2004

 Support for this report is REQUIRED.
    Implementation Note: Some clients will have only limited screen
    real estate for the display of lists of searchable properties.  In
    this case, a user might appreciate having the most frequently
    searched properties be displayed on-screen, rather than having to
    scroll through a long list of searchable properties.  One
    mechanism for signaling the most frequently searched properties is
    to return them towards the start of a list of properties.  A
    client can then preferentially display the list of properties in
    order, increasing the likelihood that the most frequently searched
    properties will appear on-screen, and will not require scrolling
    for their selection.
 Marshalling:
    The request body MUST be an empty DAV:principal-search-property-
    set XML element.
    This report is only defined when the Depth header has value "0";
    other values result in a 400 (Bad Request) error response.  Note
    that [RFC3253], Section 3.6, states that if the Depth header is
    not present, it defaults to a value of "0".
    The response body MUST be  a DAV:principal-search-property-set XML
    element, containing a DAV:principal-search-property XML element
    for each property that may be searched with the DAV:principal-
    property-search REPORT.  A server MAY limit its response to just a
    subset of the searchable properties, such as those likely to be
    useful to an interactive access control client.
    <!ELEMENT principal-search-property-set
     (principal-search-property*) >
    Each DAV:principal-search-property XML element contains exactly
    one searchable property, and a description of the property.
    <!ELEMENT principal-search-property (prop, description) >
    The DAV:prop element contains one principal property on which the
    server is able to perform a DAV:principal-property-search REPORT.
    prop: see RFC 2518, Section 12.11

Clemm, et al. Standards Track [Page 57] RFC 3744 WebDAV Access Control Protocol May 2004

    The description element is a human-readable description of what
    information this property represents.  Servers MUST indicate the
    human language of the description using the xml:lang attribute and
    SHOULD consider the HTTP Accept-Language request header when
    selecting one of multiple available languages.
    <!ELEMENT description #PCDATA >

9.5.1. Example: DAV:principal-search-property-set REPORT

 In this example, the client determines the set of searchable
 principal properties by requesting the DAV:principal-search-
 property-set REPORT on the root of the server's principal URL
 collection set, identified by http://www.example.com/users/.
 >> Request <<
 REPORT /users/ HTTP/1.1
 Host: www.example.com
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxx
 Accept-Language: en, de
 Authorization: BASIC d2FubmFtYWs6cGFzc3dvcmQ=
 Depth: 0
 <?xml version="1.0" encoding="utf-8" ?>
 <D:principal-search-property-set xmlns:D="DAV:"/>
 >> Response <<
 HTTP/1.1 200 OK
 Content-Type: text/xml; charset="utf-8"
 Content-Length: xxx
 <?xml version="1.0" encoding="utf-8" ?>
 <D:principal-search-property-set xmlns:D="DAV:">
   <D:principal-search-property>
     <D:prop>
       <D:displayname/>
     </D:prop>
     <D:description xml:lang="en">Full name</D:description>
   </D:principal-search-property>
   <D:principal-search-property>
     <D:prop xmlns:B="http://BigCorp.com/ns/">
       <B:title/>

Clemm, et al. Standards Track [Page 58] RFC 3744 WebDAV Access Control Protocol May 2004

     </D:prop>
     <D:description xml:lang="en">Job title</D:description>
   </D:principal-search-property>
 </D:principal-search-property-set>

10. XML Processing

 Implementations of this specification MUST support the XML element
 ignore rule, as specified in Section 23.3.2 of [RFC2518], and the XML
 Namespace recommendation [REC-XML-NAMES].
 Note that use of the DAV namespace is reserved for XML elements and
 property names defined in a standards-track or Experimental IETF RFC.

11. Internationalization Considerations

 In this specification, the only human-readable content can be found
 in the description XML element, found within the DAV:supported-
 privilege-set property.  This element contains a human-readable
 description of the capabilities controlled by a privilege.  As a
 result, the description element must be capable of representing
 descriptions in multiple character sets.  Since the description
 element is found within a WebDAV property, it is represented on the
 wire as XML [REC-XML], and hence can leverage XML's language tagging
 and character set encoding capabilities.  Specifically, XML
 processors at minimum must be able to read XML elements encoded using
 the UTF-8 [RFC3629] encoding of the ISO 10646 multilingual plane.
 XML examples in this specification demonstrate use of the charset
 parameter of the Content-Type header, as defined in [RFC3023], as
 well as the XML "encoding" attribute, which together provide charset
 identification information for MIME and XML processors.  Furthermore,
 this specification requires server implementations to tag description
 fields with the xml:lang attribute (see Section 2.12 of [REC-XML]),
 which specifies the human language of the description.  Additionally,
 server implementations should take into account the value of the
 Accept-Language HTTP header to determine which description string to
 return.
 For XML elements other than the description element, it is expected
 that implementations will treat the property names, privilege names,
 and values as tokens, and convert these tokens into human-readable
 text in the user's language and character set when displayed to a
 person.  Only a generic WebDAV property display utility would display
 these values in their raw form to a human user.
 For error reporting, we follow the convention of HTTP/1.1 status
 codes, including with each status code a short, English description
 of the code (e.g., 200 (OK)).  While the possibility exists that a

Clemm, et al. Standards Track [Page 59] RFC 3744 WebDAV Access Control Protocol May 2004

 poorly crafted user agent would display this message to a user,
 internationalized applications will ignore this message, and display
 an appropriate message in the user's language and character set.
 Further internationalization considerations for this protocol are
 described in the WebDAV Distributed Authoring protocol specification
 [RFC2518].

12. Security Considerations

 Applications and users of this access control protocol should be
 aware of several security considerations, detailed below.  In
 addition to the discussion in this document, the security
 considerations detailed in the HTTP/1.1 specification [RFC2616], the
 WebDAV Distributed Authoring Protocol specification [RFC2518], and
 the XML Media Types specification [RFC3023] should be considered in a
 security analysis of this protocol.

12.1. Increased Risk of Compromised Users

 In the absence of a mechanism for remotely manipulating access
 control lists, if a single user's authentication credentials are
 compromised, only those resources for which the user has access
 permission can be read, modified, moved, or deleted.  With the
 introduction of this access control protocol, if a single compromised
 user has the ability to change ACLs for a broad range of other users
 (e.g., a super-user), the number of resources that could be altered
 by a single compromised user increases.  This risk can be mitigated
 by limiting the number of people who have write-acl privileges across
 a broad range of resources.

12.2. Risks of the DAV:read-acl and DAV:current-user-privilege-set

     Privileges
 The ability to read the access privileges (stored in the DAV:acl
 property), or the privileges permitted the currently authenticated
 user (stored in the DAV:current-user-privilege-set property) on a
 resource may seem innocuous, since reading an ACL cannot possibly
 affect the resource's state.  However, if all resources have world-
 readable ACLs, it is possible to perform an exhaustive search for
 those resources that have inadvertently left themselves in a
 vulnerable state, such as being world-writable.  In particular, the
 property retrieval method PROPFIND, executed with Depth infinity on
 an entire hierarchy, is a very efficient way to retrieve the DAV:acl
 or DAV:current-user-privilege-set properties.  Once found, this
 vulnerability can be exploited by a denial of service attack in which
 the open resource is repeatedly overwritten.  Alternately, writable
 resources can be modified in undesirable ways.

Clemm, et al. Standards Track [Page 60] RFC 3744 WebDAV Access Control Protocol May 2004

 To reduce this risk, read-acl privileges should not be granted to
 unauthenticated principals, and restrictions on read-acl and read-
 current-user-privilege-set privileges for authenticated principals
 should be carefully analyzed when deploying this protocol.  Access to
 the current-user-privilege-set property will involve a tradeoff of
 usability versus security.  When the current-user-privilege-set is
 visible, user interfaces are expected to provide enhanced information
 concerning permitted and restricted operations, yet this information
 may also indicate a vulnerability that could be exploited.
 Deployment of this protocol will need to evaluate this tradeoff in
 light of the requirements of the deployment environment.

12.3. No Foreknowledge of Initial ACL

 In an effort to reduce protocol complexity, this protocol
 specification intentionally does not address the issue of how to
 manage or discover the initial ACL that is placed upon a resource
 when it is created.  The only way to discover the initial ACL is to
 create a new resource, then retrieve the value of the DAV:acl
 property.  This assumes the principal creating the resource also has
 been granted the DAV:read-acl privilege.
 As a result, it is possible that a principal could create a resource,
 and then discover that its ACL grants privileges that are
 undesirable.  Furthermore, this protocol makes it possible (though
 unlikely) that the creating principal could be unable to modify the
 ACL, or even delete the resource.  Even when the ACL can be modified,
 there will be a short period of time when the resource exists with
 the initial ACL before its new ACL can be set.
 Several factors mitigate this risk.  Human principals are often aware
 of the default access permissions in their editing environments and
 take this into account when writing information.  Furthermore,
 default privilege policies are usually very conservative, limiting
 the privileges granted by the initial ACL.

13. Authentication

 Authentication mechanisms defined for use with HTTP and WebDAV also
 apply to this WebDAV Access Control Protocol, in particular the Basic
 and Digest authentication mechanisms defined in [RFC2617].
 Implementation of the ACL spec requires that Basic authentication, if
 used, MUST only be supported over secure transport such as TLS.

Clemm, et al. Standards Track [Page 61] RFC 3744 WebDAV Access Control Protocol May 2004

14. IANA Considerations

 This document uses the namespace defined by [RFC2518] for XML
 elements.  That is, this specification uses the "DAV:" URI namespace,
 previously registered in the URI schemes registry.  All other IANA
 considerations mentioned in [RFC2518] are also applicable to this
 specification.

15. Acknowledgements

 This protocol is the collaborative product of the WebDAV ACL design
 team: Bernard Chester, Geoff Clemm, Anne Hopkins, Barry Lind, Sean
 Lyndersay, Eric Sedlar, Greg Stein, and Jim Whitehead.  The authors
 are grateful for the detailed review and comments provided by Jim
 Amsden, Dylan Barrell, Gino Basso, Murthy Chintalapati, Lisa
 Dusseault, Stefan Eissing, Tim Ellison, Yaron Goland, Dennis
 Hamilton, Laurie Harper, Eckehard Hermann, Ron Jacobs, Chris Knight,
 Remy Maucherat, Larry Masinter, Joe Orton, Peter Raymond, and Keith
 Wannamaker.  We thank Keith Wannamaker for the initial text of the
 principal property search sections.  Prior work on WebDAV access
 control protocols has been performed by Yaron Goland, Paul Leach,
 Lisa Dusseault, Howard Palmer, and Jon Radoff.  We would like to
 acknowledge the foundation laid for us by the authors of the DeltaV,
 WebDAV and HTTP protocols upon which this protocol is layered, and
 the invaluable feedback from the WebDAV working group.

16. References

16.1. Normative References

 [REC-XML]         Bray, T., Paoli, J., Sperberg-McQueen, C. and E.
                   Maler, "Extensible Markup Language (XML) 1.0
                   ((Third ed)", W3C REC REC-xml-20040204, February
                   2004, <http://www.w3.org/TR/2004/REC-xml-20040204>.
 [REC-XML-INFOSET] Cowan, J. and R. Tobin, "XML Information Set
                   (Second Edition)", W3C REC REC-xml-infoset-
                   20040204, February 2004,
                   <http://www.w3.org/TR/2004/REC-xml-infoset-
                   20040204/>.
 [REC-XML-NAMES]   Bray, T., Hollander, D. and A. Layman, "Namespaces
                   in XML", W3C REC REC-xml-names-19990114, January
                   1999, <http://www.w3.org/TR/1999/REC-xml-names-
                   19990114>.
 [RFC2119]         Bradner, S., "Key words for use in RFCs to Indicate
                   Requirement Levels", BCP 14, RFC 2119, March 1997.

Clemm, et al. Standards Track [Page 62] RFC 3744 WebDAV Access Control Protocol May 2004

 [RFC2518]         Goland, Y., Whitehead, E., Faizi, A., Carter, S.
                   and D. Jensen, "HTTP Extensions for Distributed
                   Authoring -- WEBDAV", RFC 2518, February 1999.
 [RFC2616]         Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
                   Masinter, L., Leach, P. and T. Berners-Lee,
                   "Hypertext Transfer Protocol -- HTTP/1.1", RFC
                   2616, June 1999.
 [RFC2617]         Franks, J., Hallam-Baker, P., Hostetler, J.,
                   Lawrence, S., Leach, P., Luotonen, A. and L.
                   Stewart, "HTTP Authentication: Basic and Digest
                   Access Authentication", RFC 2617, June 1999.
 [RFC3023]         Murata, M., St.Laurent, S. and D. Kohn, "XML Media
                   Types", RFC 3023, January 2001.
 [RFC3253]         Clemm, G., Amsden, J., Ellison, T., Kaler, C. and
                   J. Whitehead, "Versioning Extensions to WebDAV",
                   RFC 3253, March 2002.
 [RFC3530]         Shepler, S., Ed., Callaghan, B., Robinson, D.,
                   Thurlow, R., Beame, C., Eisler, M. and D. Noveck,
                   "Network File System (NFS) version 4 Protocol", RFC
                   3530, April 2003.
 [RFC3629]         Yergeau, F., "UTF-8, a transformation format of ISO
                   10646", STD 63, RFC 3629 November 2003.

16.2. Informative References

 [RFC2251]         Wahl, M., Howes, T. and S. Kille, "Lightweight
                   Directory Access Protocol (v3)", RFC 2251, December
                   1997.
 [RFC2255]         Howes, T. and M. Smith, "The LDAP URL Format", RFC
                   2255, December 1997.
 [UNICODE4]        The Unicode Consortium, "The Unicode Standard -
                   Version 4.0", Addison-Wesley , August 2003,
                   <http://www.unicode.org/versions/Unicode4.0.0/>.
                   ISBN 0321185781.

Clemm, et al. Standards Track [Page 63] RFC 3744 WebDAV Access Control Protocol May 2004

Appendix A. WebDAV XML Document Type Definition Addendum

 All XML elements defined in this Document Type Definition (DTD)
 belong to the DAV namespace. This DTD should be viewed as an addendum
 to the DTD provided in [RFC2518], section 23.1.
 <!-- Privileges -- (Section 3)>
 <!ELEMENT read EMPTY>
 <!ELEMENT write EMPTY>
 <!ELEMENT write-properties EMPTY>
 <!ELEMENT write-content EMPTY>
 <!ELEMENT unlock EMPTY>
 <!ELEMENT read-acl EMPTY>
 <!ELEMENT read-current-user-privilege-set EMPTY>
 <!ELEMENT write-acl EMPTY>
 <!ELEMENT bind EMPTY>
 <!ELEMENT unbind EMPTY>
 <!ELEMENT all EMPTY>
 <!-- Principal Properties (Section 4) -->
 <!ELEMENT principal EMPTY>
 <!ELEMENT alternate-URI-set (href*)>
 <!ELEMENT principal-URL (href)>
 <!ELEMENT group-member-set (href*)>
 <!ELEMENT group-membership (href*)>
 <!-- Access Control Properties (Section 5) -->
 <!-- DAV:owner Property (Section 5.1) -->
 <!ELEMENT owner (href?)>
 <!-- DAV:group Property (Section 5.2) -->
 <!ELEMENT group (href?)>
 <!-- DAV:supported-privilege-set Property (Section 5.3) -->
 <!ELEMENT supported-privilege-set (supported-privilege*)>
 <!ELEMENT supported-privilege
  (privilege, abstract?, description, supported-privilege*)>
 <!ELEMENT privilege ANY>
 <!ELEMENT abstract EMPTY>
 <!ELEMENT description #PCDATA>

Clemm, et al. Standards Track [Page 64] RFC 3744 WebDAV Access Control Protocol May 2004

 <!-- DAV:current-user-privilege-set Property (Section 5.4) -->
 <!ELEMENT current-user-privilege-set (privilege*)>
 <!-- DAV:acl Property (Section 5.5) -->
 <!ELEMENT acl (ace)* >
 <!ELEMENT ace ((principal | invert), (grant|deny), protected?,
  inherited?)>
 <!ELEMENT principal (href)
  | all | authenticated | unauthenticated
  | property | self)>
 <!ELEMENT all EMPTY>
 <!ELEMENT authenticated EMPTY>
 <!ELEMENT unauthenticated EMPTY>
 <!ELEMENT property ANY>
 <!ELEMENT self EMPTY>
 <!ELEMENT invert principal>
 <!ELEMENT grant (privilege+)>
 <!ELEMENT deny (privilege+)>
 <!ELEMENT privilege ANY>
 <!ELEMENT protected EMPTY>
 <!ELEMENT inherited (href)>
 <!-- DAV:acl-restrictions Property (Section 5.6) -->
 <!ELEMENT acl-restrictions (grant-only?, no-invert?,
  deny-before-grant?, required-principal?)>
 <!ELEMENT grant-only EMPTY>
 <!ELEMENT no-invert EMPTY>
 <!ELEMENT deny-before-grant EMPTY>
 <!ELEMENT required-principal
  (all? | authenticated? | unauthenticated? | self? | href*
  |property*)>
 <!-- DAV:inherited-acl-set Property (Section 5.7) -->
 <!ELEMENT inherited-acl-set (href*)>
 <!-- DAV:principal-collection-set Property (Section 5.8) -->

Clemm, et al. Standards Track [Page 65] RFC 3744 WebDAV Access Control Protocol May 2004

 <!ELEMENT principal-collection-set (href*)>
 <!-- Access Control and Existing Methods (Section 7) -->
 <!ELEMENT need-privileges (resource)* >
 <!ELEMENT resource ( href, privilege )
 <!-- ACL method preconditions (Section 8.1.1) -->
 <!ELEMENT no-ace-conflict EMPTY>
 <!ELEMENT no-protected-ace-conflict EMPTY>
 <!ELEMENT no-inherited-ace-conflict EMPTY>
 <!ELEMENT limited-number-of-aces EMPTY>
 <!ELEMENT grant-only EMPTY>
 <!ELEMENT no-invert EMPTY>
 <!ELEMENT deny-before-grant EMPTY>
 <!ELEMENT no-abstract EMPTY>
 <!ELEMENT not-supported-privilege EMPTY>
 <!ELEMENT missing-required-principal EMPTY>
 <!ELEMENT recognized-principal EMPTY>
 <!ELEMENT allowed-principal EMPTY>
 <!-- REPORTs (Section 9) -->
 <!ELEMENT acl-principal-prop-set ANY>
 ANY value: a sequence of one or more elements, with at most one
 DAV:prop element.
 <!ELEMENT principal-match ((principal-property | self), prop?)>
 <!ELEMENT principal-property ANY>
 ANY value: an element whose value identifies a property. The
 expectation is the value of the named property typically contains
 an href element that contains the URI of a principal
 <!ELEMENT self EMPTY>
 <!ELEMENT principal-property-search ((property-search+), prop?) >
 <!ELEMENT property-search (prop, match) >
 <!ELEMENT match #PCDATA >
 <!ELEMENT principal-search-property-set (
  principal-search-property*) >
 <!ELEMENT principal-search-property (prop, description) >
 <!ELEMENT description #PCDATA >

Clemm, et al. Standards Track [Page 66] RFC 3744 WebDAV Access Control Protocol May 2004

Appendix B. WebDAV Method Privilege Table (Normative)

 The following table of WebDAV methods (as defined in RFC 2518, 2616,
 and 3253) clarifies which privileges are required for access for each
 method.  Note that the privileges listed, if denied, MUST cause
 access to be denied.  However, given that a specific implementation
 MAY define an additional custom privilege to control access to
 existing methods, having all of the indicated privileges does not
 mean that access will be granted.  Note that lack of the indicated
 privileges does not imply that access will be denied, since a
 particular implementation may use a sub-privilege aggregated under
 the indicated privilege to control access.  Privileges required refer
 to the current resource being processed unless otherwise specified.

Clemm, et al. Standards Track [Page 67] RFC 3744 WebDAV Access Control Protocol May 2004

 +---------------------------------+---------------------------------+
 | METHOD                          | PRIVILEGES                      |
 +---------------------------------+---------------------------------+
 | GET                             | <D:read>                        |
 | HEAD                            | <D:read>                        |
 | OPTIONS                         | <D:read>                        |
 | PUT (target exists)             | <D:write-content> on target     |
 |                                 | resource                        |
 | PUT (no target exists)          | <D:bind> on parent collection   |
 |                                 | of target                       |
 | PROPPATCH                       | <D:write-properties>            |
 | ACL                             | <D:write-acl>                   |
 | PROPFIND                        | <D:read> (plus <D:read-acl> and |
 |                                 | <D:read-current-user-privilege- |
 |                                 | set> as needed)                 |
 | COPY (target exists)            | <D:read>, <D:write-content> and |
 |                                 | <D:write-properties> on target  |
 |                                 | resource                        |
 | COPY (no target exists)         | <D:read>, <D:bind> on target    |
 |                                 | collection                      |
 | MOVE (no target exists)         | <D:unbind> on source collection |
 |                                 | and <D:bind> on target          |
 |                                 | collection                      |
 | MOVE (target exists)            | As above, plus <D:unbind> on    |
 |                                 | the target collection           |
 | DELETE                          | <D:unbind> on parent collection |
 | LOCK (target exists)            | <D:write-content>               |
 | LOCK (no target exists)         | <D:bind> on parent collection   |
 | MKCOL                           | <D:bind> on parent collection   |
 | UNLOCK                          | <D:unlock>                      |
 | CHECKOUT                        | <D:write-properties>            |
 | CHECKIN                         | <D:write-properties>            |
 | REPORT                          | <D:read> (on all referenced     |
 |                                 | resources)                      |
 | VERSION-CONTROL                 | <D:write-properties>            |
 | MERGE                           | <D:write-content>               |
 | MKWORKSPACE                     | <D:write-content> on parent     |
 |                                 | collection                      |
 | BASELINE-CONTROL                | <D:write-properties> and        |
 |                                 | <D:write-content>               |
 | MKACTIVITY                      | <D:write-content> on parent     |
 |                                 | collection                      |
 +---------------------------------+---------------------------------+

Clemm, et al. Standards Track [Page 68] RFC 3744 WebDAV Access Control Protocol May 2004

Index

 A
    ACL method  40
 C
    Condition Names
       DAV:allowed-principal (pre)  42
       DAV:deny-before-grant (pre)  41
       DAV:grant-only (pre)  41
       DAV:limited-number-of-aces (pre)  41
       DAV:missing-required-principal (pre)  42
       DAV:no-abstract (pre)  41
       DAV:no-ace-conflict (pre)  41
       DAV:no-inherited-ace-conflict (pre)  41
       DAV:no-invert (pre)  41
       DAV:no-protected-ace-conflict (pre)  41
       DAV:not-supported-privilege (pre)  42
       DAV:number-of-matches-within-limits (post)  48, 53
       DAV:recognized-principal (pre)  42
 D
    DAV header
       compliance class 'access-control'  38
    DAV:acl property  23
    DAV:acl-principal-prop-set report  48
    DAV:acl-restrictions property  27
    DAV:all privilege  13
    DAV:allowed-principal precondition  42
    DAV:alternate-URI-set property  14
    DAV:bind privilege  12
    DAV:current-user-privilege-set property  21
    DAV:deny-before-grant precondition  41
    DAV:grant-only precondition  41
    DAV:group property  18
    DAV:group-member-set property  14
    DAV:group-membership property  14
    DAV:inherited-acl-set property  29
    DAV:limited-number-of-aces precondition  41
    DAV:missing-required-principal precondition  42
    DAV:no-abstract precondition  41
    DAV:no-ace-conflict precondition  41
    DAV:no-inherited-ace-conflict precondition  41
    DAV:no-invert precondition  41
    DAV:no-protected-ace-conflict precondition  41
    DAV:not-supported-privilege precondition  42
    DAV:number-of-matches-within-limits postcondition  48, 53
    DAV:owner property  15

Clemm, et al. Standards Track [Page 69] RFC 3744 WebDAV Access Control Protocol May 2004

    DAV:principal resource type  13
    DAV:principal-collection-set property  30
    DAV:principal-match report  50
    DAV:principal-property-search  51
    DAV:principal-search-property-set  56
    DAV:principal-URL property  14
    DAV:read privilege  10
    DAV:read-acl privilege  11
    DAV:read-current-user-privilege-set privilege  12
    DAV:recognized-principal precondition  42
    DAV:supported-privilege-set property  18
    DAV:unbind privilege  12
    DAV:unlock privilege  11
    DAV:write privilege  10
    DAV:write-acl privilege  12
    DAV:write-content privilege  10
    DAV:write-properties privilege  10
 M
    Methods
       ACL  40
 P
    Privileges
       DAV:all  13
       DAV:bind  12
       DAV:read  10
       DAV:read-acl  11
       DAV:read-current-user-privilege-set  12
       DAV:unbind  12
       DAV:unlock  11
       DAV:write  10
       DAV:write-acl  12
       DAV:write-content  11
       DAV:write-properties  10
    Properties
       DAV:acl  23
       DAV:acl-restrictions  27
       DAV:alternate-URI-set  14
       DAV:current-user-privilege-set  21
       DAV:group  18
       DAV:group-member-set  14
       DAV:group-membership  14
       DAV:inherited-acl-set  29
       DAV:owner  15
       DAV:principal-collection-set  30
       DAV:principal-URL  14
       DAV:supported-privilege-set  18

Clemm, et al. Standards Track [Page 70] RFC 3744 WebDAV Access Control Protocol May 2004

 R
    Reports
       DAV:acl-principal-prop-set  47
       DAV:principal-match  49
       DAV:principal-property-search  51
       DAV:principal-search-property-set  56
    Resource Types
       DAV:principal  13

Authors' Addresses

 Geoffrey Clemm
 IBM
 20 Maguire Road
 Lexington, MA  02421
 EMail: geoffrey.clemm@us.ibm.com
 Julian F. Reschke
 greenbytes GmbH
 Salzmannstrasse 152
 Muenster, NW  48159
 Germany
 EMail: julian.reschke@greenbytes.de
 Eric Sedlar
 Oracle Corporation
 500 Oracle Parkway
 Redwood Shores, CA  94065
 EMail: eric.sedlar@oracle.com
 Jim Whitehead
 U.C. Santa Cruz, Dept. of Computer Science
 1156 High Street
 Santa Cruz, CA  95064
 EMail: ejw@cse.ucsc.edu

Clemm, et al. Standards Track [Page 71] RFC 3744 WebDAV Access Control Protocol May 2004

Full Copyright Statement

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 to the rights, licenses and restrictions contained in BCP 78, and
 except as set forth therein, the authors retain all their rights.
 This document and the information contained herein are provided on an
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 Copies of IPR disclosures made to the IETF Secretariat and any
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 The IETF invites any interested party to bring to its attention
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Acknowledgement

 Funding for the RFC Editor function is currently provided by the
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Clemm, et al. Standards Track [Page 72]

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