One document matched: draft-ietf-webdav-acl-05.txt
Differences from draft-ietf-webdav-acl-04.txt
INTERNET-DRAFT Geoffrey Clemm, Rational Software
draft-ietf-webdav-acl-05 Anne Hopkins, Microsoft Corporation
Eric Sedlar, Oracle Corporation
Jim Whitehead, U.C. Santa Cruz
Expires July 21, 2001 April 23, 2001
WebDAV Access Control Protocol
Status of this Memo
This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups. Note that other groups
may also distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet- Drafts as reference material
or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
Abstract
This document specifies a set of methods, headers, and message bodies
that define the WebDAV Access Control extensions to the HTTP/1.1
protocol. This protocol permits a client to remotely read and modify
access control lists that instruct a server whether to grant or deny
operations upon a resource (such as HTTP method invocations) by a given
principal.
This document is a product of the Web Distributed Authoring and
Versioning (WebDAV) working group of the Internet Engineering Task
Force. Comments on this draft are welcomed, and should be addressed to
the acl@webdav.org mailing list. Other related documents can be found at
http://www.webdav.org/acl/, and http://www.ics.uci.edu/pub/ietf/webdav/.
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Table of Contents
1 INTRODUCTION......................................................4
1.1 Terms...........................................................5
1.2 Notational Conventions..........................................6
2 PRINCIPALS........................................................6
3 PRIVILEGES........................................................6
3.1 DAV:read Privilege..............................................7
3.2 DAV:write Privilege.............................................7
3.3 DAV:read-acl Privilege..........................................8
3.4 DAV:read-cuprivset Privilege....................................8
3.5 DAV:write-acl Privilege.........................................8
3.6 DAV:all Privilege...............................................8
4 PRINCIPAL PROPERTIES..............................................8
4.1 DAV:is-principal................................................9
4.2 DAV:alternate-URL...............................................9
5 ACCESS CONTROL PROPERTIES.........................................9
5.1 DAV:owner.......................................................9
5.2 DAV:supported-privilege-set....................................10
5.3 DAV:current-user-privilege-set.................................11
5.4 DAV:acl........................................................11
5.4.1 ACE Principal...............................................11
5.4.2 ACE Grant and Deny..........................................13
5.4.3 ACE Protection..............................................13
5.4.4 ACE Inheritance.............................................13
5.5 DAV:acl-semantics..............................................13
5.6 DAV:principal-collection-set...................................14
5.7 Example: PROPFIND to retrieve access control properties........14
6 ACL SEMANTICS....................................................17
6.1 ACE Combination................................................17
6.1.1 DAV:first-match ACE Combination.............................18
6.1.2 DAV:all-grant-before-any-deny ACE Combination...............18
6.1.3 DAV:specific-deny-overrides-grant ACE Combination...........18
6.2 ACE Ordering...................................................18
6.2.1 DAV:deny-before-grant ACE Ordering..........................18
6.3 Required Principals............................................18
7 ACCESS CONTROL AND EXISTING METHODS..............................19
7.1 OPTIONS........................................................19
7.1.1 Example - OPTIONS...........................................19
8 ACCESS CONTROL METHODS...........................................19
8.1 ACL............................................................19
8.1.1 ACL Preconditions...........................................20
8.1.2 Example: the ACL method.....................................20
8.1.3 Example: ACL method failure due to omission of protected ACE21
8.1.4 Example: ACL method failure due to inherited ACEs preceding
non-inherited ACEs................................................22
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8.1.5 Example: ACL method failure due to an attempt to set grant and
deny in a single ACE..............................................23
9 INTERNATIONALIZATION CONSIDERATIONS..............................24
10 SECURITY CONSIDERATIONS........................................25
10.1 Increased Risk of Compromised Users...........................25
10.2 Risks of the read-acl and cuprivset Privileges................25
11 AUTHENTICATION.................................................26
12 IANA CONSIDERATIONS............................................26
13 INTELLECTUAL PROPERTY..........................................26
14 ACKNOWLEDGEMENTS...............................................26
15 REFERENCES.....................................................27
15.1 Normative References..........................................27
15.2 Informational References......................................28
16 AUTHORS' ADDRESSES.............................................28
17 APPENDICIES....................................................28
17.1 XML Document Type Definition..................................28
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1 INTRODUCTION
The goal of the WebDAV access control extensions is to provide an
interoperable mechanism for handling discretionary access control
for content in 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 how you can access 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
"how" is 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.
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.
In the interests of timeliness, the following set of security
mechanisms are not addressed by this document:
* 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,
* Role-based security (where a role can be seen as a dynamically
defined collection of principals),
* Specification of the ways an ACL on a resource is initialized,
* Specification of an ACL that applies globally to a method,
rather than to a particular resource.
This specification is organized as follows. Section 1.1 defines key
concepts used throughout the specification, and is followed by 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 semantics of access control lists are
described in Section 6, including sections on ACE combination
(Section 6.1), ACE ordering (Section 6.2), and principals required
to be present in an ACE (Section 6.3). Client discovery of access
control capability using OPTIONS is described in Section 7.1, and
the access control setting method, ACL, is specified in Section 8.
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Internationalization considerations (Section 9) and security
considerations (Section 10) round out the specification. An
appendix (Section 17.1) provides an XML Document Type Definition
(DTD) for the XML elements defined in the specification.
1.1 Terms
This draft 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.
principal collection
A "principal collection" is a group of principals, and is
represented in this protocol by a WebDAV collection containing HTTP
resources that represent principals, and principal collections.
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 an atomic or aggregate
privilege, means the privilege cannot be set in an access control
element (ace).
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 shared from the acl of another
resource.
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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].
2 PRINCIPALS
A principal is a network resource that represents a distinct human
or computational actor that initiates access to network resources.
On many implementations, users and groups are represented as
principals; other types of principals are also possible. A URL of
any scheme MAY be used to identify a principal resource. However,
servers implementing this specification SHOULD 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. Although an implementation SHOULD support PROPFIND
and PROPPATCH to access and modify information about a principal,
it is not required to do so.
A principal resource may or may not be a collection. A collection
principal may only contain other principals (not other types of
resources). Servers that support aggregation of principals (e.g.
groups of users or other groups) MUST manifest them as collection
principals. The WebDAV methods for examining and maintaining
collections (e.g. DELETE, PROPFIND) MAY be used to maintain
collection principals. Membership in a collection principal is
recursive, so a principal in a collection principal GRPA contained
by collection principal GRPB is a member of both GRPA and GRPB.
Implementations not supporting recursive membership in principal
collections can return an error if the client attempts to bind
collection principals into other collection principals.
3 PRIVILEGES
Ability to perform a given method on a resource SHOULD 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 SHOULD be denied any HTTP access to that resource.
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 an
internal member of a collection. Since these privileges control
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the ability to update the state of a collection, these privileges
would be aggregated by the DAV:write privilege on a collection, and
granting the DAV:write privilege on a collection would also grant
the add-member and remove-member privileges.
Privileges may have the quality of being abstract, in which case
they cannot be set in an ACE. Aggregate and atomic 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
and classify non-abstract privileges.
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, WebDAV defines a set of well-known privileges (e.g.
DAV:read and DAV:write), which can at least be used to classify the
other privileges defined on a particular resource. The access
permissions on null and lock-null resources are solely those they
inherit (if any), and they are not discoverable (i.e., the ACL
properties specified in Section 5 are not defined on null and lock-
null resources). On the transition from null or lock-null to a
stateful resource, the initial access control list is set by the
server's default ACL value policy (if any).
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. Additionally, the read
privilege MAY control the OPTIONS method.
<!ELEMENT read EMPTY>
3.2 DAV:write Privilege
The write privilege controls methods that modify the state of the
resource, such as PUT and PROPPATCH. Note that state modification
is also controlled via locking (see section 5.3 of [WEBDAV]), so
effective write access requires that both write privileges and
write locking requirements are satisfied.
<!ELEMENT write EMPTY>
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3.3 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>
3.4 DAV:read-cuprivset Privilege
The DAV:read-cuprivset 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 writeable.
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-cuprivset EMPTY>
3.5 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>
3.6 DAV:all Privilege
DAV:all is an aggregate privilege that contains all privileges on
the resource.
<!ELEMENT all EMPTY>
4 PRINCIPAL PROPERTIES
Principals are manifested to clients as an HTTP resource,
identified by a URL. A principal MUST have a DAV:displayname
property. This protocol defines the following additional
properties for a principal. The name and value of these properties
SHOULD NOT be returned by PROPFIND allprop request (as defined in
Section 12.14.1 of [RFC2518]). In the descriptions below, a read-
only property is defined as a property that MUST NOT be writeable
using PROPPATCH.
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4.1 DAV:is-principal
This is a read-only property that indicates whether this resource
is a principal. A resource MUST have a non-empty DAV:is-principal
property if and only if it is a principal resource.
<!ELEMENT is-principal (#PCDATA)>
PCDATA value: "true" - resource is a principal, "false" - resource
is not a principal (note that in cases where the "F" value might be
used, this specification requires the property not be present at
all).
4.2 DAV:alternate-URL
This read-only property, if present, contains the URL of a network
resource with additional descriptive information about the
principal. This property identifies one or more additional network
resources (i.e., it contains one or more URLs) that may be
consulted by a client to gain additional knowledge concerning a
principal. Two potential uses for this property are to store an
ldap [RFC2255] or mailto [RFC2368] scheme URL. Support for this
property is OPTIONAL.
<!ELEMENT alternate-URL (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. Some access
control properties (such as DAV:owner) MAY be updated with the
PROPPATCH method. In the descriptions below, a read-only property
is defined as a property that MUST NOT be writeable using
PROPPATCH. 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.
HTTP resources that support the WebDAV Access Control Protocol MUST
contain the following properties. Null, and lock-null resources
(described in Section 7.4 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 write-ACL privilege), clients might display the resource
owner in their user interface.
<!ELEMENT owner (href prop?)>
<!ELEMENT prop (see [RFC2518], section 12.11)>
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An implementation MAY include a list of selected properties of that
principal resource. Which properties (if any) are included is
implementation defined, but might reasonably include properties
such as DAV:displayname, which is useful for the construction of
access control user interfaces on the client. A server might
support this capability if it wished to save the client the
additional network round-trip delay required to retrieve this
information using a PROPFIND request on the principal URL in the
href element. Servers that do not directly support PROPFIND on
principal resources might also support this feature, since it
allows them to return a server-controlled subset of the properties
on the principal resource.
An implementation MAY allow the use of PROPPATCH to update the
DAV:owner field. If the DAV:owner property is writeable, clients
MUST NOT submit the prop element; only the href element can be
modified by the client. The purpose of this restriction is to limit
the scope of effect of a PROPPATCH to just the owner property's
resource; setting the prop element would additionally require
modification to properties of the principal resource identified by
the href element.
5.2 DAV:supported-privilege-set
This is a read-only 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 of a resource 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.
<!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
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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.
5.3 DAV:current-user-privilege-set
DAV:current-user-privilege-set is a read-only 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 is
particularly useful for an access control user interface, which can
be constructed without knowing the ACE combining semantics of the
server. 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>
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 DAV:acl
This is a read-only 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, (grant|deny), protected?, inherited?)>
5.4.1 ACE Principal
The DAV:principal element identifies the principal to which this
ACE applies.
<!ELEMENT principal ((href, prop?)
| all | authenticated | unauthenticated
| property | self)>
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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. An implementation
MAY include a DAV:prop element after the DAV:href element,
containing a list of selected properties of that principal
resource. Which properties (if any) are included in the DAV:prop
element is implementation defined. The DAV:prop element can be used
by servers that do not support PROPFIND requests on principal
resources to return principal-related information (such as the
value of the DAV:displayname property) that a client would find
useful in the creation of an access control user interface. A
server might also support this capability if it wished to save the
client the additional network round-trip delays required to
retrieve this information via a series of PROPFIND requests on each
principal URL in the ACL. In the worst case, this is one additional
PROPFIND per ACE.
<!ELEMENT prop (see [RFC2518], section 12.11)>
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.
The current user matches a DAV:property principal in a DAV:acl
property of a resource only if the identified property of that
resource contains a DAV:href that 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 object and the
current user is authenticated as being that principal.
<!ELEMENT self EMPTY>
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5.4.2 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>
5.4.3 ACE Protection
If an ACE contains a DAV:protected element, an ACL request without
that ACE MUST fail.
<!ELEMENT protected EMPTY>
5.4.4 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 DAV:acl-semantics
This is a read-only property that defines the ACL semantics. These
semantics define how multiple ACEs that match the current user are
combined, what are the constraints on how ACEs can be ordered, and
which principals must have an ACE. A client user interface could
use the value of this property to provide feedback to a human
operator concerning the impact of proposed changes to an ACL.
Alternately, a client could use this property to determine exactly,
before submitting an ACL method invocation, what ACL changes it
needs to make to accomplish a specific goal (or whether that goal
is even achievable on this server).
Since it is not practical to require all implementations to use the
same ACL semantics, the DAV:acl-semantics property is used to
identify the ACL semantics for a particular resource. The DAV:acl-
semantics element is defined in section 6.
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5.6 DAV:principal-collection-set
This read-only property contains zero, one, or more URLs that
identify a collection principal. It is expected that
implementations of this protocol will typically employ a relatively
small number of locations in the URL namespace for principal, and
collection principals. In cases where this assumption holds, the
DAV:principal-collection-set property will contain a small set of
URLs identifying the top of collection hierarchy containing
multiple principals and collection principals. An access control
protocol user agent could use the contents of DAV:principal-
collection-set to query 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
collection principals, and therefore clients should not assume they
have retrieved an exhaustive listing. Additionally, a server MAY
elect to report none of the collection principals it knows about.
5.7 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.foo.org
Content-type: text/xml; charset="utf-8"
Content-Length: xxx
Depth: 0
Authorization: Digest username="ejw",
realm="users@foo.org", nonce="...",
uri="/top/container/", response="...", opaque="..."
<?xml version="1.0" encoding="utf-8" ?>
<D:propfind xmlns:D="DAV:">
<D:owner/>
<D:supported-privilege-set/>
<D:current-user-privilege-set/>
<D:acl/>
</D:propfind>
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>> 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.webdav.org/acl/"> <D:response> <D:propstat>
<D:status>HTTP/1.1 200 OK</D:status>
<D:prop>
<D:owner>
<D:href>http://www.foo.org/users/gclemm</D:href> </D:owner>
<D:supported-privilege-set>
<D:supported-privilege>
<D:privilege> <D:all/> </D:privilege>
<D:abstract/>
<D:description>Any operation</D:description>
<D:supported-privilege>
<D:privilege> <D:read/> </D:privilege>
<D:description>Read any object</D:description>
</D:supported-privilege>
<D:supported-privilege>
<D:privilege> <D:write/> </D:privilege>
<D:abstract/>
<D:description>Write any object</D:description>
<D:supported-privilege>
<D:privilege> <A:create/> </D:privilege>
<D:description>Create an object</D:description>
</D:supported-privilege>
<D:supported-privilege>
<D:privilege> <A:update/> </D:privilege>
<D:description>Update an object</D:description>
</D:supported-privilege>
<D:supported-privilege>
<D:privilege> <A:delete/> </D:privilege>
<D:description>Delete an object</D:description>
</D:supported-privilege>
</D:supported-privilege>
<D:supported-privilege>
<D:privilege> <D:read-acl/> </D:privilege>
<D:description>Read the ACL</D:description>
</D:supported-privilege>
<D:supported-privilege>
<D:privilege> <D:write-acl/> </D:privilege>
<D:description>Write the ACL</D:description>
</D:supported-privilege>
</D:supported-privilege>
</D:supported-privilege-set>
<D:current-user-privilege-set>
<D:privilege> <D:read/> </D:privilege>
<D:privilege> <D:read-acl/> </D:privilege>
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</D:current-user-privilege-set>
<D:acl>
<D:ace>
<D:principal>
<D:href>http://www.foo.org/users/esedlar</D:href>
<D:prop>
<D:displayname>Eric Sedlar</D:displayname>
</D:prop> </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.foo.org/groups/marketing/</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.foo.org/top/</D:href> </D:inherited>
</D:ace> </D:acl>
</D:prop>
</D:propstat> </D:response> </D:multistatus>
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:
DAV:all (aggregate, abstract)
|
+-- DAV:read
+-- DAV:write (aggregate, abstract)
|
+-- http://www.webdav.org/acl/create
+-- http://www.webdav.org/acl/update
+-- http://www.webdav.org/acl/delete
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+-- 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.foo.org/users/esedlar is granted the DAV:read,
DAV:write, and DAV:read-acl privileges.
ACE #2: The principals identified by the URL
http://www.foo.org/groups/marketing/ are denied the DAV:read
privilege. In this example, the principal URL identifies a group,
which is represented by a collection principal.
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.foo.org/top/, the parent collection of this resource.
6 ACL SEMANTICS
The ACL semantics define how multiple ACEs that match the current
user are combined, what are the constraints on how ACEs can be
ordered, and which principals must have an ACE.
<!ELEMENT acl-semantics acl-sem*>
<!ELEMENT acl-sem (ace-combination, ace-ordering, required-
principal*)>
6.1 ACE Combination
The DAV:ace-combination element defines how privileges from
multiple ACEs that match the current user will be combined to
determine the access privileges for that user. Multiple ACEs may
match the same user because the same principal can appear in
multiple ACEs, because multiple principals can identify the same
user, and because one principal can be a member of another
principal.
<!ELEMENT ace-combination
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(first-match | all-grant-before-any-deny | specific-deny-
overrides-grant)>
6.1.1 DAV:first-match ACE Combination
The ACEs are evaluated in the order in which they appear in the
ACL. If the first ACE that matches the current user does not grant
all the privileges needed for the request, the request MUST fail.
<!ELEMENT first-match EMPTY>
6.1.2 DAV:all-grant-before-any-deny ACE Combination
The ACEs are evaluated in the order in which they appear in the
ACL. If an evaluated ACE denies a privilege needed for the
request, the request MUST fail. If all ACEs have been evaluated
without the user being granted all privileges needed for the
request, the request MUST fail.
<!ELEMENT all-grant-before-any-deny EMPTY>
6.1.3 DAV:specific-deny-overrides-grant ACE Combination
All ACEs in the ACL are evaluated. An "individual ACE" is one
whose principal identifies the current user. A "group ACE" is one
whose principal is a collection that contains a principal that
identifies the current user. A privilege is granted if it is
granted by an individual ACE and not denied by an individual ACE,
or if it is granted by a group ACE and not denied by an individual
or group ACE. A request MUST fail if any of its needed privileges
are not granted.
<!ELEMENT specific-deny-overrides-grant EMPTY>
6.2 ACE Ordering
The DAV:ace-ordering element defines a constraint on how the ACEs
can be ordered in the ACL.
<!ELEMENT ace-ordering (deny-before-grant)? >
6.2.1 DAV:deny-before-grant ACE Ordering
This element indicates that all deny ACEs must precede all grant
ACEs.
<!ELEMENT deny-before-grant EMPTY>
6.3 Required Principals
The required principal elements identify which principals must have
an ACE defined in the ACL.
<!ELEMENT required-principal
(href | all | authenticated | unauthenticated | property | self)>
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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>
7 ACCESS CONTROL AND EXISTING METHODS
This section defines the impact of access control functionality on
existing methods.
7.1 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.
7.1.1 Example - OPTIONS
>> Request <<
OPTIONS /foo.html HTTP/1.1
Host: www.webdav.org
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.
8 ACCESS CONTROL METHODS
8.1 ACL
The ACL method modifies the DAV:acl property of a resource. A new
DAV:acl value must be written in its entirety, including any
inherited ACEs. Unless 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. If a server restricts the set of ACEs
visible to the current user via the DAV:acl property, then the ACL
request would only replace the set of ACEs visible to the current
user, and would not affect any ACE that was not visible.
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.
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When submitting ACEs, clients MUST NOT include the optional prop
element (a child of the principal element). The purpose of this
restriction is to limit the scope of effect of the ACL method to
just the resource identified by the Request-URI; setting the prop
element would additionally require property modification for one or
more principal resources.
8.1.1 ACL Preconditions
An implementation MAY enforce one or more of the following
constraints on an ACL request. If the constraint is violated, a
403 (Forbidden) response MUST be returned and the indicated XML
element MUST be returned in the response body.
<DAV:protected/>: An implementation MAY protect an ACE from
modification or deletion. For example, some implementations
implicitly grant the DAV:owner of a resource DAV:read-acl and
DAV:write-acl privileges, and this cannot be changed by a client.
<DAV:too-many-aces/>: An implementation MAY limit the number of
ACEs in an ACL. However, ACL-compliant servers MUST support at
least one ACE granting privileges to a single principal, and one
ACE granting privileges to a collection principal.
<DAV:non-inherited-must-precede-inherited/>: All non-inherited ACEs
MUST precede all inherited ACEs.
<DAV:deny-must-precede-grant/>: All non-inherited deny ACEs MUST
precede all non-inherited grant ACEs.
If the following precondition is not met, the server MUST return a
409 (Conflict) response, and the indicated XML element MUST be
returned in the response body:
<DAV:inhereted-exist-parent>: Inherited ACEs MUST exist on a parent
resource.
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.foo.org/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 inherited from the parent collection
http://www.foo.bar/top/.
>> Request <<
ACL /top/container/ HTTP/1.1
Host: www.foo.org
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
Authorization: Digest username="fielding",
realm="users@foo.org", nonce="...",
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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.foo.org/users/esedlar</D:href>
</D:principal>
<D:grant>
<D:privilege> <D:read/> </D:privilege>
<D:privilege> <D:write/> </D:privilege> </D:grant>
</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.foo.org/top/</D:href> </D:inherited>
</D:ace> </D:acl>
>> Response <<
HTTP/1.1 200 OK
8.1.3 Example: ACL method failure due to omission of protected ACE
In the following request, user "fielding", authenticated by
information in the Authorization header, attempts to grant the
principal identified by the URL http://www.foo.org/users/esedlar
(i.e., the user "esedlar") read privileges. Prior to the request,
the DAV:acl property on the resource contained a protected ACE (see
Section 5.4.3) granting DAV:owner the DAV:read-acl and DAV:write-
acl privileges. The ACL method invocation fails because this
protected ACE is omitted, thus violating the semantics of ACE
protection..
>> Request <<
ACL /top/container/ HTTP/1.1
Host: www.foo.org
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
Authorization: Digest username="fielding",
realm="users@foo.org", nonce="...",
uri="/top/container/", response="...", opaque="..."
<?xml version="1.0" encoding="utf-8" ?>
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<D:acl xmlns:D="DAV:">
<D:ace>
<D:principal>
<D:href>http://www.foo.org/users/esedlar</D:href>
</D:principal>
<D:grant>
<D:privilege> <D:read/> </D:privilege> </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" ?>
<DAV:protected/>
8.1.4 Example: ACL method failure due to inherited ACEs preceding non-
inherited ACEs
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.foo.org/top/index.html. This
resource has two inherited ACEs.
Inherited ACE #1 grants the principal identified by URL
http://www.foo.org/users/ejw (i.e., the user "ejw")
http://www.foo.org/privs/write-all and DAV:read-acl privileges. On
this server, http://www.foo.org/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 add a third ACE, granting the principal
identified by the URL http://www.foo.org/users/gclemm (i.e., the
user ôgclemmö) DAV:write permission, but in the request places the
inherited ACEs before the non-inherited ACEs, causing an error on
this specific server implementation. Note that on a different
implementation, this request might be accepted.
>> Request <<
ACL /top/index.html HTTP/1.1
Host: www.foo.org
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
Authorization: Digest username="ejw",
realm="users@foo.org", nonce="...",
uri="/top/index.html", response="...", opaque="..."
<?xml version="1.0" encoding="utf-8" ?>
<D:acl xmlns:D="DAV:" xmlns:F="http://www.foo.org/privs/">
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<D:ace>
<D:principal>
<D:href>http://www.foo.org/users/ejw</D:href>
</D:principal>
<D:grant>
<D:privilege><F:write-all/></D:privilege>
<D:privilege><D:read-acl/></D:privilege>
</D:grant>
<D:inherited/>
</D:ace>
<D:ace>
<D:principal><D:all/></D:principal>
<D:grant><D:read/></D:grant>
<D:inherited/>
</D:ace>
<D:ace>
<D:principal>
<D:href>http://www.foo.org/users/gclemm</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" ?>
<DAV:non-inherited-must-precede-inherited/>
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.foo.org/diamond/engagement-ring.gif. The
ACL request includes a single, syntactically and semantically
incorrect ACE, which attempts to grant the collection principal
identified by the URL http://www.foo.org/users/friends/ DAV:read
privilege and deny the principal identified by URL
http://www.foo.org/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.
>> Request <<
ACL /diamond/engagement-ring.gif HTTP/1.1
Host: www.foo.org
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
Authorization: Digest username="ygoland",
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realm="users@foo.org", 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.foo.org/users/friends/</D:href>
</D:principal>
<D:grant><D:read/></D:grant>
<D:principal>
<D:href>http://www.foo.org/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 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 must, at minimum, be able to read XML elements encoded
using the UTF-8 [UTF-8] 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.
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.
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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
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].
10 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.
10.1 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.
10.2 Risks of the read-acl and cuprivset 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-writeable. 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,
writeable resources can be modified in undesirable ways.
To reduce this risk, read-acl privileges should not be granted to
unauthenticated principals, and restrictions on read-acl and
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cuprivset 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.
11 AUTHENTICATION
Authentication mechanisms defined in WebDAV also apply to this
WebDAV Access Control Protocol, in particular the Basic and Digest
authentication mechanisms defined in [RFC2617].
12 IANA CONSIDERATIONS
This document uses the namespace defined by [RFC2518] for XML
elements. All other IANA considerations mentioned in [RFC2518]
also applicable to WebDAV ACL.
13 INTELLECTUAL PROPERTY
The following notice is copied from RFC 2026, section 10.4, and
describes the position of the IETF concerning intellectual property
claims made against this document.
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use other technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on
the IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances
of licenses to be made available, or the result of an attempt made
to obtain a general license or permission for the use of such
proprietary rights by implementers or users of this specification
can be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to practice
this standard. Please address the information to the IETF
Executive Director.
14 ACKNOWLEDGEMENTS
This protocol is the collaborative product of the WebDAV ACL design
team: Bernard Chester, Geoff Clemm (Rational), Anne Hopkins
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INTERNET-DRAFT WebDAV ACL April 23, 2001
(Microsoft), Barry Lind (Xythos), Sean Lyndersay (Microsoft), Eric
Sedlar (Oracle), Greg Stein (Apache.org), and Jim Whitehead (UC
Santa Cruz). The authors are grateful for the detailed review and
comments provided by Jim Amsden, Gino Basso, Murthy Chintalapati,
Dennis Hamilton, Laurie Harper, Ron Jacobs, Chris Knight, and Remy
Maucherat. 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 WebDAV and HTTP protocols upon
which this protocol is layered, and the invaluable feedback from
the WebDAV working group.
15 REFERENCES
15.1 Normative References
[RFC2119] S.Bradner, "Key words for use in RFCs to Indicate
Requirement Levels." RFC 2119, BCP 14, Harvard, March, 1997.
[REC-XML] T. Bray, J. Paoli, C.M. Sperberg-McQueen, "Extensible
Markup Language (XML)." World Wide Web Consortium Recommendation
REC-xml-19980210. http://www.w3.org/TR/REC-xml-19980210.
[RFC2616] R. Fielding, J. Gettys, J. C. Mogul, H. Frystyk, L.
Masinter, P. Leach, and T. Berners-Lee, "Hypertext Transfer
Protocol -- HTTP/1.1." RFC 2616. U.C.Irvine, Compaq, Xerox,
Microsoft, MIT/LCS, June, 1999.
[RFC2617] J. Franks, P. Hallam-Baker, J. Hostetler, S. Lawrence, P.
Leach, A. Luotonen, L. Stewart, "HTTP Authentication: Basic and
Digest Access Authentication. " RFC 2617. Northwestern University,
Verisign, AbiSource, Agranat, Microsoft, Netscape, Open Market,
June, 1999.
[RFC2518] Y. Goland, E. Whitehead, A. Faizi, S. R. Carter, D.
Jensen, "HTTP Extensions for Distributed Authoring -- WEBDAV." RFC
2518. Microsoft, U.C.Irvine, Netscape, Novell, February, 1999.
[RFC2368] P. Hoffman, L. Masinter, J. Zawinski, "The mailto URL
scheme." RFC 2368. Internet Mail Consortium, Xerox, Netscape, July,
1998.
[RFC2255] T. Howes, M. Smith, "The LDAP URL Format." RFC 2255.
Netscape, December, 1997.
[RFC3023] M. Murata, S. St.Laurent, D. Kohn, "XML Media Types." RFC
3023. IBM Tokyo Research Laboratory, simonstl.com, Skymoon
Ventures, January, 2001.
[UTF-8] F. Yergeau, "UTF-8, a transformation format of Unicode and
ISO 10646." RFC 2279. Alis Technologies. January, 1998.
Clemm, Hopkins, Sedlar, Whitehead [Page 27]
INTERNET-DRAFT WebDAV ACL April 23, 2001
15.2 Informational References
[RFC2026] S.Bradner, "The Internet Standards Process -- Revision 3."
RFC 2026, BCP 9. Harvard, October, 1996.
16 AUTHORS' ADDRESSES
Geoffrey Clemm
Rational Software
20 Maguire Road
Lexington, MA 02421
Email: geoffrey.clemm@rational.com
Anne Hopkins
Microsoft Corporation
One Microsoft Way
Redmond, WA 98052
Email: annehop@microsoft.com
Eric Sedlar
Oracle Corporation
500 Oracle Parkway
Redwood Shores, CA 94065
Email: esedlar@us.oracle.com
Jim Whitehead
U.C. Santa Cruz
Dept. of Computer Science
Baskin Engineering
1156 High Street
Santa Cruz, CA 95064
Email: ejw@cse.ucsc.edu
17 APPENDICIES
17.1 XML Document Type Definition
<!-- Privileges -->
<!ELEMENT read EMPTY>
<!ELEMENT write EMPTY>
<!ELEMENT read-acl EMPTY>
<!ELEMENT read-cuprivset EMPTY>
<!ELEMENT write-acl EMPTY>
<!ELEMENT all EMPTY>
<!-- Principal Properties (Section 4) -->
<!ELEMENT is-principal (#PCDATA)>
<!ELEMENT alternate-URL (href*)>
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<!-- Access Control Properties (Section 5) -->
<!-- DAV:owner Property (Section 5.1) -->
<!ELEMENT owner (href prop?)>
<!ELEMENT prop (see [RFC2518], section 12.11)>
<!-- DAV:supported-privilege-set Property (Section 5.2) -->
<!ELEMENT supported-privilege-set (supported-privilege*)>
<!ELEMENT supported-privilege
(privilege, abstract?, description, supported-privilege*)>
<!ELEMENT privilege ANY>
<!ELEMENT abstract EMPTY>
<!ELEMENT description #PCDATA>
<!ELEMENT privilege ANY>
<!-- DAV:current-user-privilege-set Property (Section 5.3) -->
<!ELEMENT current-user-privilege-set (privilege*)>
<!-- DAV:acl Property (Section 5.4) -->
<!ELEMENT acl (ace*)>
<!ELEMENT ace (principal, (grant|deny), protected?, inherited?)>
<!ELEMENT principal ((href, prop?)
| all | authenticated | unauthenticated
| property | self)>
<!ELEMENT prop (see [RFC2518], section 12.11)>
<!ELEMENT all EMPTY>
<!ELEMENT authenticated EMPTY>
<!ELEMENT unauthenticated EMPTY>
<!ELEMENT property ANY>
<!ELEMENT self EMPTY>
<!ELEMENT grant (privilege+)>
<!ELEMENT deny (privilege+)>
<!ELEMENT privilege ANY>
<!ELEMENT protected EMPTY>
<!ELEMENT inherited (href)>
<!-- DAV:principal-collection-set Property (Section 5.6) -->
<!ELEMENT principal-collection-set (href*)>
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<!-- DAV:acl-semantics Property (Section 6) -->
<!ELEMENT acl-semantics acl-sem*>
<!ELEMENT acl-sem (ace-combination, ace-ordering, required-
principal*)>
<!ELEMENT ace-combination
(first-match | all-grant-before-any-deny | specific-deny-
overrides-grant)>
<!ELEMENT first-match EMPTY>
<!ELEMENT all-grant-before-any-deny EMPTY>
<!ELEMENT specific-deny-overrides-grant EMPTY>
<!ELEMENT ace-ordering (deny-before-grant)? >
<!ELEMENT deny-before-grant EMPTY>
<!ELEMENT required-principal
(href | all | authenticated | unauthenticated | property | self)>
<!-- ACL method preconditions (Section 8.1.1) -->
<!ELEMENT protected EMPTY>
<!ELEMENT too-many-aces EMPTY>
<!ELEMENT non-inherited-must-precede-inherited EMPTY>
<!ELEMENT deny-must-precede-grant EMPTY>
<!ELEMENT acl-requires-lock-token EMPTY>
<!ELEMENT inherited-exist-parent EMPTY>
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