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Revert unpublished XEP 258 changes 

This patch reverts changes to XEP 258 originally committed with:
    c1173e8cf7a40a936e68a873069e191b846c7182

The previous two commits should be a no-op (I mistakenly hit
'push' instead of 'commit' when trying to construct this patch,
and then reverted that mistake.)
This commit is contained in:
Kurt Zeilenga 2010-10-17 13:02:58 -07:00
parent 560b05f8a9
commit c3cd0f554b
1 changed files with 396 additions and 411 deletions
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807
xep-0258.xml
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@ -12,113 +12,94 @@
]>
<?xml-stylesheet type='text/xsl' href='xep.xsl'?>
<xep>
<header>
<title>Security Labels in XMPP</title>
<abstract>This document describes the use of security labels in XMPP. The document specifies
how security label metadata is carried in XMPP, when this metadata should or should not
be provided, and how the metadata is to be processed.</abstract>
&LEGALNOTICE;
<number>0258</number>
<status>Experimental</status>
<type>Standards Track</type>
<sig>Standards</sig>
<approver>Council</approver>
<dependencies>
<spec>XMPP Core</spec>
<spec>XEP-0001</spec>
<spec>XEP-0285</spec>
</dependencies>
<supersedes/>
<supersededby/>
<shortname>sec-label</shortname>
&kdz;
<revision>
<version>0.7</version>
<date>2010-09-29</date>
<initials>kdz</initials>
<remark>
<p>Add initial support for secure binding of labels (digital signatures).</p>
</remark>
</revision>
<revision>
<version>0.6</version>
<date>2010-07-30</date>
<initials>kdz</initials>
<remark>
<p>Extend catalog handling. Minor editorial changes.</p>
</remark>
</revision>
<revision>
<version>0.5</version>
<date>2009-07-27</date>
<initials>kdz</initials>
<remark>
<p>Remove &LABEL;/&EQUIVALENTLABEL; type= attribute. Clarify label catalog
discovery. Clarify syntax of selector= attribute.</p>
</remark>
</revision>
<revision>
<version>0.4</version>
<date>2009-07-23</date>
<initials>kdz</initials>
<remark>
<p>Update label catalogs to include user input selector.</p>
</remark>
</revision>
<revision>
<version>0.3</version>
<date>2009-03-20</date>
<initials>kdz</initials>
<remark>
<p>Add text regarding default bg/fg colors. Correct examples.</p>
</remark>
</revision>
<revision>
<version>0.2</version>
<date>2009-03-10</date>
<initials>kdz</initials>
<remark>
<p>Reworked discovery and various updates.</p>
</remark>
</revision>
<revision>
<version>0.1</version>
<date>2009-01-05</date>
<initials>psa</initials>
<remark>
<p>Initial published version.</p>
</remark>
</revision>
<revision>
<version>0.0.081203</version>
<date>2008-12-03</date>
<initials>kdz</initials>
<remark>
<p>Initial draft.</p>
</remark>
</revision>
</header>
<header>
<title>Security Labels in XMPP</title>
<abstract>This document describes the use of security labels in XMPP. The document
specifies how security label metadata is carried in XMPP, when this metadata
should or should not be provided, and how the metadata is to be processed.</abstract>
&LEGALNOTICE;
<number>0258</number>
<status>Experimental</status>
<type>Standards Track</type>
<sig>Standards</sig>
<approver>Council</approver>
<dependencies>
<spec>XMPP Core</spec>
<spec>XEP-0001</spec>
</dependencies>
<supersedes/>
<supersededby/>
<shortname>sec-label</shortname>
<author>
<firstname>Kurt</firstname>
<surname>Zeilenga</surname>
<email>Kurt.Zeilenga@Isode.COM</email>
<jid>Kurt.Zeilenga@Isode.COM</jid>
</author>
<revision>
<version>0.6</version>
<date>2010-07-30</date>
<initials>kdz</initials>
<remark><p>Extend catalog handling. Minor editorial changes.</p></remark>
</revision>
<revision>
<version>0.5</version>
<date>2009-07-27</date>
<initials>kdz</initials>
<remark><p>Remove &LABEL;/&EQUIVALENTLABEL; type= attribute. Clarify label catalog discovery. Clarify syntax of selector= attribute.</p></remark>
</revision>
<revision>
<version>0.4</version>
<date>2009-07-23</date>
<initials>kdz</initials>
<remark><p>Update label catalogs to include user input selector.</p></remark>
</revision>
<revision>
<version>0.3</version>
<date>2009-03-20</date>
<initials>kdz</initials>
<remark><p>Add text regarding default bg/fg colors. Correct examples.</p></remark>
</revision>
<revision>
<version>0.2</version>
<date>2009-03-10</date>
<initials>kdz</initials>
<remark><p>Reworked discovery and various updates.</p></remark>
</revision>
<revision>
<version>0.1</version>
<date>2009-01-05</date>
<initials>psa</initials>
<remark><p>Initial published version.</p></remark>
</revision>
<revision>
<version>0.0.081203</version>
<date>2008-12-03</date>
<initials>kdz</initials>
<remark><p>Initial draft.</p></remark>
</revision>
</header>
<section1 topic="Introduction" anchor="intro">
<p>A security label, sometimes referred to as a confidentiality label, is a structured
representation of the sensitivity of a piece of information. A security label is used in
conjunction with a clearance, a structured representation of what information
sensitivities a person (or other entity) is authorized to access, and a security policy
to control access to each piece of information. For instance, message could be labeled
as "SECRET", and hence requiring the sender and the receiver to have a clearance
granting access to "SECRET" information. &X.841; provides a discussion of security
labels, clearances, and security policy.</p>
<p>Sensitivity-based authorization is used in networks which operate under a set of
information classification rules, such as in government military agency networks. The
standardized formats for security labels, clearances, and security policy are
generalized and do have application in non-government networks.</p>
<p>This document describes the use of security labels in &xmpp;. The document specifies how
security label metadata is carried in XMPP. It standardizes a mechanism for carrying ESS
Security Labels in XMPP, as well as provides for use of other label formats. ESS
Security Labels are specified in &rfc2634;. ESS Security Labels are commonly used in
conjunction with &X.500; clearances and either X.841 or &SDN.801c; security
policies.</p>
<example caption="Message with ESS Security Label"><![CDATA[
<section1 topic='Introduction' anchor='intro'>
<p>A security label, sometimes referred to as a confidentiality label, is
a structured representation of the sensitivity of a piece of information. A security
label is used in conjunction with a clearance, a structured representation of what
information sensitivities a person (or other entity) is authorized to access, and a security
policy to control access to each piece of information. For instance, message could be
labeled as "SECRET", and hence requiring the sender and the receiver to have a
clearance granting access to "SECRET" information. &X.841; provides a discussion of
security labels, clearances, and security policy.</p>
<p>Sensitivity-based authorization is used in networks which operate under a set of
information classification rules, such as in government military agency networks. The
standardized formats for security labels, clearances, and security policy are
generalized and do have application in non-government networks.</p>
<p>This document describes the use of security labels in &xmpp;. The document specifies
how security label metadata is carried in XMPP. It standardizes a mechanism for
carrying ESS Security Labels in XMPP, as well as provides for use of other label
formats. ESS Security Labels are specified in &rfc2634;. ESS Security Labels are
commonly used in conjunction with &X.500; clearances and either X.841 or &SDN.801c;
security policies.</p>
<example caption="Message with ESS Security Label"><![CDATA[
<message to='romeo@example.net' from='juliet@example.com/balcony'>
<body>This content is classified.</body>
<securitylabel xmlns='urn:xmpp:sec-label:0'>
@ -129,7 +110,7 @@
</securitylabel>
</message>
]]></example>
<example caption="Message with IC-ISM Label"><![CDATA[
<example caption="Message with IC-ISM Label"><![CDATA[
<message to='romeo@example.net' from='juliet@example.com/balcony'>
<body>This content is classified.</body>
<securitylabel xmlns='urn:xmpp:sec-label:0'>
@ -139,67 +120,37 @@
</securitylabel>
</message>
]]></example>
<p>Note: The &IC-ISM; label example is for <em>illustrative purposes only</em>.</p>
<p>To securely bind the security label to the message, &xep0285; can be used as detailed below.</p>
<example caption="Message with Securely bound ESS Security Label"><![CDATA[
<message to='romeo@example.net' from='juliet@example.com/balcony'>
<signed xmlns="urn:xmpp:signed:0">
<signature algorithm="RSA-SHA1">To-be-computed
</signature>
<data>
PG1lc3NhZ2UgdG89J3JvbWVvQGV4YW1wbGUubmV0JyBmcm9tPSdqdWxpZXRAZXhhbXBsZS5jb20v
YmFsY29ueSc+CiAgICA8Ym9keT5UaGlzIGNvbnRlbnQgaXMgY2xhc3NpZmllZC48L2JvZHk+CiAg
ICA8c2VjdXJpdHlsYWJlbCB4bWxucz0ndXJuOnhtcHA6c2VjLWxhYmVsOjAnPgogICAgICAgIDxk
aXNwbGF5bWFya2luZyBmZ2NvbG9yPSdibGFjaycgYmdjb2xvcj0ncmVkJz5TRUNSRVQ8L2Rpc3Bs
YXltYXJraW5nPgogICAgICAgIDxsYWJlbD48aWNpc21sYWJlbCB4bWxucz0naHR0cDovL2V4YW1w
bGUuZ292L0lDLUlTTS8wJyBjbGFzc2lmaWNhdGlvbj0nUycKICAgICAgICAgICAgb3duZXJQcm9k
dWNlcj0nVVNBJy8+PC9sYWJlbD4KICAgIDwvc2VjdXJpdHlsYWJlbD4KPC9tZXNzYWdlPgo=
</data>
</message>
]]>
</example>
<p>The document details when security label metadata should or should not be provided, and
how this metadata is to be processed.</p>
<p>Note: The &IC-ISM; label example is for <em>illustrative purposes only</em>.</p>
<p>The document details when security label metadata should or should not be provided, and how
this metadata is to be processed.</p>
<p>This document does <em>not</em> provide:
<ul>
<li>any mechanism for a client might discover the security policy enforce at its
home server, or any other server;</li>
<li>any mechanism for a client to discover the user's clearance, or the clearance of
associated with any resource; nor</li>
<li>any administrative mechanism for a client to configure configure policy,
clearance, and labels of any resource.</li>
</ul>
Such mechanisms may be introduced in subsequent documents.</p>
</section1>
<p>This document does <em>not</em> provide:
<ul>
<li>any mechanism for a client might discover the security policy
enforce at its home server, or any other server;</li>
<li>any mechanism for a client to discover the user's clearance,
or the clearance of associated with any resource; nor</li>
<li>any administrative mechanism for a client to configure
configure policy, clearance, and labels of any resource.</li>
</ul>
<section1 topic="Discovering Feature Support" anchor="disco">
<p>If an entity supports the XMPP Security Label protocol, it MUST report that fact by
including a service discovery feature of "<tt>urn:xmpp:sec-label:0</tt>" in response to
a &xep0030; information request. Clients wishing to include a XMPP Security Label
element in any stanza they generate SHOULD determine if their server supports the XMPP
Security Label protocol. If their server does not support XMPP Security Label, the
client SHOULD NOT generate XMPP Security Labels as the server not supporting this
protocol will generally ignore XMPP Security Labels as they would any other unrecognized
element.</p>
<p>If an entity supports secure binding of the XMPP Security Label using &xmppdsig;, it MUST
report the fact by including a service discover feature of
"<tt>urn:xmpp:sec-label:dsig:0</tt>"" in response to a &xep0030; information request.
Clients wishing to include a securely bound XMPP Security Label element in any stanza
they generate SHOULD determine if their server supports the XMPP Security Label
protocol. If their server does not support securely bound XMPP Security Label, the
client SHOULD NOT generate securely bound XMPP Security Labels as the server not
supporting this protocol will generally ignore securely bound XMPP Security Labels as
they would any other unrecognized element. Note that the client here is signing
the stanzas for the benifit of its server. Its server will determine what content,
if any, to forward to other entities. Hence, the sending client need determine whether
any of the intended receipents supports XMPP Digital Signatures.</p>
<p>As each service domain may have different support for security labels, servers should
advertise and clients should perform appropriate discovery lookups on a per service
basis.</p>
<example caption="Service Discovery information request"><![CDATA[
Such mechanisms may be introduced in subsequent documents.</p>
</section1>
<section1 topic='Discovering Feature Support' anchor='disco'>
<p>If an entity supports the XMPP Security Label protocol, it MUST report that fact
by including a service discovery feature of "<tt>urn:xmpp:sec-label:0</tt>" in
response to a &xep0030; information request. Clients wishing to include a XMPP
Security Label element in any stanza they generate SHOULD determine if their
server supports the XMPP Security Label protocol. If their server does not
support XMPP Security Label, the client SHOULD NOT generate XMPP Security Labels
as the server not supporting this protocol will generally ignore XMPP Security
Labels as they would any other unrecognized element.</p>
<p>As each service domain may have different support for security labels, servers
should advertise and clients should perform appropriate discovery lookups on a
per service basis.</p>
<example caption="Service Discovery information request"><![CDATA[
<iq type='get'
from='user@example.com/Work'
to='example.com'
@ -207,7 +158,7 @@
<query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>
]]></example>
<example caption="Service Discovery information response"><![CDATA[
<example caption="Service Discovery information response"><![CDATA[
<iq type='result'
from='example.com'
to='user@example.com/Work'
@ -215,22 +166,21 @@
<query xmlns='http://jabber.org/protocol/disco#info'>
...
<feature var='urn:xmpp:sec-label:0'/>
<feature var='urn:xmpp:sec-label:dsig:0'/>
...
</query>
</iq>
]]></example>
<!--
<!--
<p>A server should only include &IDENTITY; elements in the response for services
the user is cleared to use.</p>
-->
</section1>
</section1>
<section1 topic="Protocol" anchor="protocol">
<p>An element, &SECURITYLABEL;, is defined to carry security label metadata. This metadata
includes a security label, zero or more equivalent security labels, and optionally
display marking data.</p>
<example caption="Labeled Message"><![CDATA[
<section1 topic='Protocol' anchor='protocol'>
<p>An element, &SECURITYLABEL;, is defined to carry security label metadata. This metadata
includes a security label, zero or more equivalent security labels, and optionally display
marking data.</p>
<example caption="Labeled Message"><![CDATA[
<message to='romeo@example.net' from='juliet@example.com/balcony'>
<body>This content is classified.</body>
<securitylabel xmlns='urn:xmpp:sec-label:0'>
@ -246,77 +196,93 @@
</securitylabel>
</message>
]]></example>
<p>The security label metadata is carried in an &SECURITYLABEL; element. The &SECURITYLABEL;
element which contains one and only one &LABEL; element, zero or more &EQUIVALENTLABEL;
elements, and an optional &DISPLAYMARKING; element.</p>
<p>The &LABEL; provides the primary security label. It is commonly issued by the sender
under the security policy of that they and their home server operating under. The
&LABEL; contains either a single element representing the primary security label or is
empty to indicate use of a default.</p>
<p>Each &EQUIVALENTLABEL; represents an equivalent security label under other policies. Each
&EQUIVALENTLABEL; contains a single element representing the equivalent label. This
element might be used when a recepient is known to hold a clearance under a different
policy than the sender.</p>
<p>The &DISPLAYMARKING; element contains a display string for use by implementations which
are unable to utilize the applicable security policy to generate display markings. The
element may optionally contain two attributes, <tt>fgcolor=</tt> and <tt>bgcolor=</tt>,
whose values are HTML color strings (e.g., '<tt>red</tt>' or '<tt>#ff0000</tt>'), for
use in colorizing the display marking. The <tt>fgcolor=</tt> default is <tt>black</tt>.
The <tt>bgcolor=</tt> default is <tt>white</tt>. </p>
</section1>
<p>The security label metadata is carried in an &SECURITYLABEL; element.
The &SECURITYLABEL; element which contains one and only one &LABEL; element,
zero or more &EQUIVALENTLABEL; elements, and an optional &DISPLAYMARKING; element.</p>
<p>The &LABEL; provides the primary security label. It is commonly issued
by the sender under the security policy of that they and their home
server operating under. The &LABEL; contains either a single element
representing the primary security label or is empty to indicate use of
a default.</p>
<p>Each &EQUIVALENTLABEL; represents an equivalent security label under
other policies. Each &EQUIVALENTLABEL; contains a single element
representing the equivalent label. This element might be used when
a recepient is known to hold a clearance under a different policy
than the sender.</p>
<p>The &DISPLAYMARKING; element contains a display string for use by
implementations which are unable to utilize the applicable security policy
to generate display markings. The element may optionally contain two
attributes, <tt>fgcolor=</tt> and <tt>bgcolor=</tt>, whose values are HTML
color strings (e.g., '<tt>red</tt>' or '<tt>#ff0000</tt>'), for use in
colorizing the display marking. The <tt>fgcolor=</tt> default is <tt>black</tt>.
The <tt>bgcolor=</tt> default is <tt>white</tt>.
</p>
</section1>
<section1 topic="Label Catalog Discovery" anchor="label-catalog">
<p>A client can request a catalog for a particular JID by sending a catalog discovery
request to the client's server. Where the JID is hosted by some other server, the
client's server is expected to produce a suitable catalog (or fail the request). The
client's server may, as needed, query catalogs from other servers in order to fulfill
the client's request.</p>
<p>While this specification does not preclude a client from directing a catalog request
elsewhere, it is noted that catalog returned by a party other than its server may not be
directly useable by the client. For instance, the client's server might require a
particular only-locally-known label be used in messages to a particular remote JID.</p>
<p>It is RECOMMENDED the server publish catalogs of security label for use by clients.</p>
<p>If catalog is restrictive, as indicated by the restrictive attribute with value of true,
the client SHOULD use one of the labels (or no label) offered by the catalog.</p>
<p>One and only one of the items may have a default attribute with value of true. The client
should default to this item in cases where the user has not selected an item.</p>
<p>An item may have no label. Such an item offers a choice of sending a stanza without a
label.</p>
<p>Each catalog provided should only contain labels for which the client is allowed to use
(based upon the user's authorization) in a particular context (such as in chatroom). A
catalog may not be include the complete set of labels available for the use by the
client in the context.</p>
<blockquote>Note: the single catalog per context approach used here is likely inadequate in
enviroments where there are a large number of labels in use. It is expected that a more
sophisticated approach will be introduced in a subsequent revision of this
specification.</blockquote>
<p>As each service domain may have different support for security labels, servers should
advertise and clients should perform appropriate discovery lookups on a per service
basis.</p>
<p>To indicate the support for label catalog discovery, a server advertises the
<tt>urn:xmpp:sec-label:catalog:2</tt> feature. The following pair of examples
illustrates this feature discovery.</p>
<p>Each item in the catalog may contain a selector attribute. The value of this attribute
represents the item's placement in a hierarchical organization of the items. The value
of the selector attribute conforms to the selector-value ABNF production: <blockquote>
<![CDATA[
<section1 topic='Label Catalog Discovery' anchor='label-catalog'>
<p>A client can request a catalog for a particular JID by sending
a catalog discovery request to the client's server. Where the JID
is hosted by some other server, the client's server is expected to
produce a suitable catalog (or fail the request). The client's server
may, as needed, query catalogs from other servers in order to
fulfill the client's request.</p>
<p>While this specification does not preclude a client from directing
a catalog request elsewhere, it is noted that catalog returned by
a party other than its server may not be directly useable by the
client. For instance, the client's server might require a particular
only-locally-known label be used in messages to a particular remote
JID.</p>
<p>It is RECOMMENDED the server publish catalogs of security label
for use by clients.</p>
<p>If catalog is restrictive, as indicated by the restrictive attribute
with value of true, the client SHOULD use one of the labels
(or no label) offered by the catalog.</p>
<p>One and only one of the items may have a default attribute with
value of true. The client should default to this item in cases
where the user has not selected an item.</p>
<p>An item may have no label. Such an item offers a choice of
sending a stanza without a label.</p>
<p>Each catalog provided should only contain labels for which the client
is allowed to use (based upon the user's authorization) in a particular
context (such as in chatroom). A catalog may not be include the
complete set of labels available for the use by the client in the
context.</p>
<blockquote>Note: the single catalog per context approach used here
is likely inadequate in enviroments where there are a large number
of labels in use. It is expected that a more sophisticated approach
will be introduced in a subsequent revision of this
specification.</blockquote>
<p>As each service domain may have different support for security labels,
servers should advertise and clients should perform appropriate
discovery lookups on a per service basis.</p>
<p>To indicate the support for label catalog discovery, a server
advertises the <tt>urn:xmpp:sec-label:catalog:2</tt> feature.
The following pair of examples illustrates this feature discovery.</p>
<p>Each item in the catalog may contain a selector attribute. The
value of this attribute represents the item's placement in a
hierarchical organization of the items. The value of the selector
attribute conforms to the selector-value ABNF production:
<blockquote>
<![CDATA[
selector-value = (<item>"|")*<item>
]]>
</blockquote>
</p>
<p>where &lt;item&gt; is a sequence of characters not including "|".</p>
<p>A value of "X|Y|Z" indicates that this item is "Z" in the the "Y" subset of the "X"
subset of items. This information may be used, for instance, in generating label
selection menus in graphical user interfaces.</p>
<blockquote>Note: use of unnecessarily deep hierarchies should be avoided.</blockquote>
<example caption="Label Catalog Feature Discovery request"><![CDATA[
</blockquote>
</p>
<p>where &lt;item&gt; is a sequence of characters not including "|".</p>
<p>A value of "X|Y|Z" indicates that this item is "Z" in the
the "Y" subset of the "X" subset of items. This information may
be used, for instance, in generating label selection menus in
graphical user interfaces.</p>
<blockquote>Note: use of unnecessarily deep hierarchies should be
avoided.</blockquote>
<example caption="Label Catalog Feature Discovery request"><![CDATA[
<iq type='get'
from='user@example.com/Work'
id='disco1'>
<query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>
]]></example>
<example caption="Label Information Feature Discovery response"><![CDATA[
<example caption="Label Information Feature Discovery response"><![CDATA[
<iq type='result'
from='example.com'
to='user@example.com/Work'
@ -328,18 +294,16 @@ selector-value = (<item>"|")*<item>
</query>
</iq>
]]></example>
<p>The following example pair illustrates catalog discovery. Note that client directs the &IQ; to its server regardless of which catalog it requests (via the to= attribute of in &CATALOG; element).</p>
<p>The following example pair illustrates catalog discovery. Note that client directs the
&IQ; to its server regardless of which catalog it requests (via the to= attribute of in
&CATALOG; element).</p>
<example caption="Label Catalog request"><![CDATA[
<example caption="Label Catalog request"><![CDATA[
<iq type='get' id='cat1'>
<catalog xmlns='urn:xmpp:sec-label:catalog:2' to='example.com'/>
</iq>
]]></example>
<example caption="Label Catalog Get response"><![CDATA[
<example caption="Label Catalog Get response"><![CDATA[
<iq type='result' to='user@example.com/Work' id='cat1'>
<catalog xmlns='urn:xmpp:sec-label:catalog:2'
to='example.com' name='Default'
@ -376,113 +340,122 @@ selector-value = (<item>"|")*<item>
</catalog>
</iq>
]]></example>
</section1>
</section1>
<section1 topic="Use in XMPP" anchor="xmpp-use">
<p>The sensitivity-based access control decisions discussed herein are to be made
independently of other access control decisions or other facilities. That is, the
sensitivity-based access control decisions are not conditional on other factors.</p>
<p>It is intended that &SECURITYLABEL; elements are only used as prescribed by this
document, or other formal specifications. Any other use of &SECURITYLABEL; SHOULD be
viewed as a protocol violation. The stanza SHOULD be discarded with, if approrpriate, an
error response. Such error responses SHOULD NOT include content from the violating
stanza, excepting that necessary to well-formed error responses.</p>
<p>When use of a &SECURITYLABEL; element is prescribed, that use is RECOMMENDED. Absence of
a &SECURITYLABEL; element implies the stanza has the default label as specified in the
governing security policy. Given that the governing policy may not specify a default
label, hence denying access to the stanza, supporting clients SHOULD provide a
&SECURITYLABEL; element where prescribed.</p>
<p>Typically, a client would allow the user to choose populate the &SECURITYLABEL; from one
of from a small set of security labels selections known to it (through configuration
and/or discovery and/or other means), such as from a pull-down menu. That selection
would include appropriate values for the &LABEL;, &DISPLAYMARKING;, and
&EQUIVALENTLABEL; elements.</p>
<p>A policy-aware client may provide the user with an interface allowing the user to produce
custom labeling data for inclusion in this set. A policy-aware client SHOULD preclude
the user from producing &LABEL; values which the user's own clearance does not grant
access to, and SHOULD preclude sending any label which the user's own clearance does not
grant access to. Each &EQUIVALENTLABEL; value, if any, MUST be equivalent under an
equivalent policy to the &LABEL;. The &DISPLAYMARKING; element SHOULD be set the display
marking prescribed for the &LABEL; under the governing policy, or, if the governing
policy prescribes no display marking for the &LABEL;, absent.</p>
<p>A client which receives a stanza with &SECURITYLABEL; element is to promiently display
the &DISPLAYMARKING; value. A policy-aware may alternatively promiently display the
marking for the &LABEL; prescribed by the governing policy.</p>
<p>Each server is expected to make a number of sensitivity-based authorization decisions.
Each decision is made by evaluating an Access Control Decision Function (ACDF) with a
governing policy, a clearance, and a security label. The ACDF yields either
<em>Grant</em> or <em>Deny</em>.</p>
<p>If the user holds a valid clearance (known to the server) under the governing policy, the
clearance input is the user's clearance. Otherwise, if the governing policy provides a
default clearance, the clearance input is the default clearance. Otherwise, the
clearance input is the nil clearance. The nil clearance is a clearance for which the
ACDF always returns Deny when given as the clearance input.</p>
<p>If the stanza contains a &SECURITYLABEL; element and the either the &LABEL; element or
one of the &EQUIVALENTLABEL; elements contain an appropriate label, that label input is
that label. Otherwise, the label input is the default label provided the governing
policy or, if no default label is provided, the nil label. The nil label is a label for
which the ACDF always returns Deny when given as the label input.</p>
<p>The term "effective clearance" and "effective label" refer, respectively, to the
clearance and label provided as input to the ACDF.</p>
<p>Not all sensitivity-based authorization decisions an XMPP server might make involve a
user clearance and/or stanza label. A server may only provide service to users which
hold an appropriate clearance as determined by calling the ACDF with the user's
clearance and a label associated with the service. A clearance might also be associated
with the service to restrict the set of labels may be used in labeling stanzas. Labels
and clearances can also be associated with network interfaces, remote servers,
chatrooms, pubsub notes.</p>
<section2 topic="Use in Instant Messaging" anchor="im-use">
<p>A client may provide a &SECURITYLABEL; element in any &MESSAGE; it sends.</p>
<!--
<section1 topic='Use in XMPP' anchor='xmpp-use'>
<p>The sensitivity-based access control decisions discussed herein are to be
made independently of other access control decisions or other facilities.
That is, the sensitivity-based access control decisions are not conditional
on other factors.</p>
<p>It is intended that &SECURITYLABEL; elements are only used as prescribed by
this document, or other formal specifications. Any other use of
&SECURITYLABEL; SHOULD be viewed as a protocol violation. The stanza SHOULD
be discarded with, if approrpriate, an error response. Such error responses
SHOULD NOT include content from the violating stanza, excepting that
necessary to well-formed error responses.</p>
<p>When use of a &SECURITYLABEL; element is prescribed, that use is RECOMMENDED.
Absence of a &SECURITYLABEL; element implies the stanza has the default label
as specified in the governing security policy. Given that the governing
policy may not specify a default label, hence denying access to the stanza,
supporting clients SHOULD provide a &SECURITYLABEL; element where prescribed.</p>
<p>Typically, a client would allow the user to choose populate the
&SECURITYLABEL; from one of from a small set of security labels selections
known to it (through configuration and/or discovery and/or other means),
such as from a pull-down menu. That selection would include appropriate
values for the &LABEL;, &DISPLAYMARKING;, and &EQUIVALENTLABEL; elements.</p>
<p>A policy-aware client may provide the user with an interface allowing the
user to produce custom labeling data for inclusion in this set. A
policy-aware client SHOULD preclude the user from producing &LABEL; values
which the user's own clearance does not grant access to, and SHOULD preclude
sending any label which the user's own clearance does not grant access to.
Each &EQUIVALENTLABEL; value, if any, MUST be equivalent under an equivalent
policy to the &LABEL;. The &DISPLAYMARKING; element SHOULD be set the
display marking prescribed for the &LABEL; under the governing policy, or,
if the governing policy prescribes no display marking for the &LABEL;,
absent.</p>
<p>A client which receives a stanza with &SECURITYLABEL; element is to promiently
display the &DISPLAYMARKING; value. A policy-aware may alternatively
promiently display the marking for the &LABEL; prescribed by the governing
policy.</p>
<p>Each server is expected to make a number of sensitivity-based authorization
decisions. Each decision is made by evaluating an Access Control Decision
Function (ACDF) with a governing policy, a clearance, and a security label.
The ACDF yields either <em>Grant</em> or <em>Deny</em>.</p>
<p>If the user holds a valid clearance (known to the server) under the
governing policy, the clearance input is the user's clearance. Otherwise,
if the governing policy provides a default clearance, the clearance input
is the default clearance. Otherwise, the clearance input is the nil clearance.
The nil clearance is a clearance for which the ACDF always returns Deny when
given as the clearance input.</p>
<p>If the stanza contains a &SECURITYLABEL; element and the either the &LABEL;
element or one of the &EQUIVALENTLABEL; elements contain an appropriate label,
that label input is that label. Otherwise, the label input is the default
label provided the governing policy or, if no default label is provided,
the nil label. The nil label is a label for which the ACDF always returns
Deny when given as the label input.</p>
<p>The term "effective clearance" and "effective label" refer, respectively,
to the clearance and label provided as input to the ACDF.</p>
<p>Not all sensitivity-based authorization decisions an XMPP server might make
involve a user clearance and/or stanza label. A server may only provide
service to users which hold an appropriate clearance as determined by calling
the ACDF with the user's clearance and a label associated with the service.
A clearance might also be associated with the service to restrict the set
of labels may be used in labeling stanzas. Labels and clearances can also
be associated with network interfaces, remote servers, chatrooms, pubsub
notes.</p>
<section2 topic='Use in Instant Messaging' anchor='im-use'>
<p>A client may provide a &SECURITYLABEL; element in any &MESSAGE; it sends.</p>
<!--
<p>The server will make, at a minimum, the following accessing control decisions:
<ul>
<li>TBD</li>
</ul>
</p>
-->
</section2>
<section2 topic="Use in Group Chat and Multi-User Chat" anchor="muc-use">
<p>A client may provide a &SECURITYLABEL; element in &MESSAGE; stanzas.</p>
<section3 topic="Discovery" anchor="muc-disco">
<p>A server SHOULD provide a label feature and information discovery for the
room.</p>
<p>Clients SHOULD discover label feature and information on a per room basis.</p>
</section3>
<section3 topic="Sending Messages" anchor="muc-send">
<p>Sending groupchat messages is similiar to sending normal messages, however their
are a few differences.</p>
<p>Groupchat messages are addressed to the room. The room clearance must be suitable
for the message label, else it should be rejected.</p>
<p>The room's clearance may allow a variety of labels to be used. Not all partipants
may be cleared for all labels allowed in the room. The server MUST only deliver
messages to partipants for which they are cleared to receive.</p>
</section3>
<section3 topic="Private Messages" anchor="muc-private">
<p>Private messages are treated as discussed in the "Use in Instant Messaging"
section. (Should private messages be restricted by room's configuration?)</p>
</section3>
<section3 topic="Invitations" anchor="muc-invite">
<p>Invitations may be labeled.</p>
</section3>
<section3 topic="Changing Subject" anchor="muc-subject">
<p>This section discusses semantics of &SECURITYLABEL; elements contained in
&MESSAGE; stanzas containing a &SUBJECT; element.</p>
<p>The presence of a &SECURITYLABEL; element indicates a request to change the
room's label, either to the provided label or, if the element is empty, to unset
the room's label. The server is to refuse the request if the requestor is not
authorized to change the subject, not cleared for the requested label, or if the
server is otherwise unwilling or unable to make the change. If the label change
is refused, so must the accompanied subject change. Likewise, if the subject
change is refused, so must the accompanied label change.</p>
<p>Upon change of the room's label, the server MUST immediately remove from the room
all members whom are not cleared for that label.</p>
<p>In absence of a &SECURITYLABEL; element, the label associated with the room is
unchanged.</p>
<p>The room's label can also be changed through room configuration (to be discussed
in later revision of this document).</p>
</section3>
<!--
</section2>
<section2 topic='Use in Group Chat and Multi-User Chat' anchor='muc-use'>
<p>A client may provide a &SECURITYLABEL; element in &MESSAGE; stanzas.</p>
<section3 topic='Discovery' anchor='muc-disco'>
<p>A server SHOULD provide a label feature and information discovery for the room.</p>
<p>Clients SHOULD discover label feature and information on a per room basis.</p>
</section3>
<section3 topic='Sending Messages' anchor='muc-send'>
<p>Sending groupchat messages is similiar to sending normal messages, however
their are a few differences.</p>
<p>Groupchat messages are addressed to the room. The room clearance must
be suitable for the message label, else it should be rejected.</p>
<p>The room's clearance may allow a variety of labels to be used. Not all
partipants may be cleared for all labels allowed in the room. The server
MUST only deliver messages to partipants for which they are cleared to
receive.</p>
</section3>
<section3 topic='Private Messages' anchor='muc-private'>
<p>Private messages are treated as discussed in the "Use in Instant Messaging"
section. (Should private messages be restricted by room's configuration?)</p>
</section3>
<section3 topic='Invitations' anchor='muc-invite'>
<p>Invitations may be labeled.</p>
</section3>
<section3 topic='Changing Subject' anchor='muc-subject'>
<p>This section discusses semantics of &SECURITYLABEL; elements contained
in &MESSAGE; stanzas containing a &SUBJECT; element.</p>
<p>The presence of a &SECURITYLABEL; element indicates a request to change
the room's label, either to the provided label or, if the element is empty,
to unset the room's label. The server is to refuse the request if the
requestor is not authorized to change the subject, not cleared for the
requested label, or if the server is otherwise unwilling or unable to make
the change. If the label change is refused, so must the accompanied
subject change. Likewise, if the subject change is refused, so must the
accompanied label change.</p>
<p>Upon change of the room's label, the server MUST immediately remove from
the room all members whom are not cleared for that label.</p>
<p>In absence of a &SECURITYLABEL; element, the label associated with the
room is unchanged.</p>
<p>The room's label can also be changed through room configuration (to be
discussed in later revision of this document).</p>
</section3>
<!--
<section3 topic='Room Configuration' anchor='muc-config'>
<p>The server may allow for configuration of security label parameters
via room configuration mechanisms. The approach is intended to be
@ -555,23 +528,23 @@ selector-value = (<item>"|")*<item>
]]></example>
</section3>
-->
</section2>
<section2 topic="Use in Presence" anchor="presence-use">
<p>&SECURITYLABEL; elements are not to appear in &PRESENCE; stanzas. Server SHALL treat
any &PRESENCE; stanza that contains a &SECURITYLABEL; as a protocol violation.</p>
<p>Presence information is subject to sensitivity-base authorization decisions, however
these decisions are made are made using a label associated with the presence
resource, such as a chatroom's label.</p>
</section2>
<section2 topic="Use in PubSub" anchor="pubsub-use">
<section3 topic="Discovery" anchor="pubsub-disco">
<p>A server SHOULD provide a label feature and information discovery for each
node.</p>
<p>Clients SHOULD discover label feature and information on a per node basis.</p>
</section3>
<section3 topic="Publishing items with Security Labels" anchor="muc-send">
<p>Each item may be individually labeled.</p>
<example caption="Publishing with a Security Label"><![CDATA[
</section2>
<section2 topic='Use in Presence' anchor='presence-use'>
<p>&SECURITYLABEL; elements are not to appear in &PRESENCE; stanzas. Server
SHALL treat any &PRESENCE; stanza that contains a &SECURITYLABEL; as a
protocol violation.</p>
<p>Presence information is subject to sensitivity-base authorization decisions,
however these decisions are made are made using a label associated with the
presence resource, such as a chatroom's label.</p>
</section2>
<section2 topic='Use in PubSub' anchor='pubsub-use'>
<section3 topic='Discovery' anchor='pubsub-disco'>
<p>A server SHOULD provide a label feature and information discovery for each node.</p>
<p>Clients SHOULD discover label feature and information on a per node basis.</p>
</section3>
<section3 topic='Publishing items with Security Labels' anchor='muc-send'>
<p>Each item may be individually labeled.</p>
<example caption="Publishing with a Security Label"><![CDATA[
<iq type='set'
from='hamlet@denmark.lit/blogbot'
to='pubsub.shakespeare.lit'
@ -605,8 +578,8 @@ And by opposing end them?
</pubsub>
</iq>
]]></example>
<p>The service then notifies appropriately cleared subscribers.</p>
<example caption="Publishing with a Security Label"><![CDATA[
<p>The service then notifies appropriately cleared subscribers.</p>
<example caption="Publishing with a Security Label"><![CDATA[
<message from='pubsub.shakespeare.lit' to='francisco@denmark.lit' id='foo'>
<event xmlns='http://jabber.org/protocol/pubsub#event'>
<items node=princely_musings'>
@ -637,42 +610,45 @@ And by opposing end them?
</event>
</iq>
]]></example>
</section3>
</section2>
</section1>
</section3>
</section2>
</section1>
<section1 topic="Extension Considerations" anchor="exts">
<p> This extension is itself is extensible. In particular, the &LABEL; and &EQUIVALENTLABEL;
elements are designed to hold a range of security labels formats. XML namespaces SHOULD
be used to avoid name clashes. </p>
</section1>
<section1 topic='Extension Considerations' anchor='exts'>
<p>
This extension is itself is extensible. In particular, the &LABEL; and &EQUIVALENTLABEL;
elements are designed to hold a range of security labels formats. XML namespaces SHOULD
be used to avoid name clashes.
</p>
</section1>
<!--
<!--
<section1 topic='Implementation Notes' anchor='impl'>
<p>OPTIONAL.</p>
</section1>
-->
<section1 topic="Security Considerations" anchor="security">
<p>This document is all about authorization, a key aspect of security. Hence, security
considerations are discussed through this document.</p>
<p>Security labels generally should be securely bound to the object. This may be
accomplished through use of &xmppdsig; as discussed in Appendix A.</p>
<p>Certain XMPP stanzas, such as &PRESENCE; stanzas, are not themselves subject to any
sensitity-based authorization decisions, and may be forwarded throughout the XMPP
network. The content of these stanzas should not contain information requiring
sensitivity-based dissemination controls.</p>
</section1>
<section1 topic="IANA Considerations" anchor="iana">
<p>This document requires no interaction with &IANA;.</p>
</section1>
<section1 topic="XMPP Registrar Considerations" anchor="registrar">
<p>It is requested the &REGISTRAR; add the extension's namespaces and schemas to appropriate
XMPP registries.</p>
</section1>
<section1 topic="XML Schemas" anchor="schema">
<section2 topic="Extension Schema" anchor="schema-sl">
<p>
<code><![CDATA[
<section1 topic='Security Considerations' anchor='security'>
<p>This document is all about authorization, a key aspect of security. Hence,
security considerations are discussed through this document.</p>
<p>Security labels generally should be securely bound to the object. This may be
accomplished through use of &xmppe2e; signing, or possibly other signing
mechanisms.</p>
<p>Certain XMPP stanzas, such as &PRESENCE; stanzas, are not themselves subject
to any sensitity-based authorization decisions, and may be forwarded throughout
the XMPP network. The content of these stanzas should not contain information
requiring sensitivity-based dissemination controls.</p>
</section1>
<section1 topic='IANA Considerations' anchor='iana'>
<p>This document requires no interaction with &IANA;.</p>
</section1>
<section1 topic='XMPP Registrar Considerations' anchor='registrar'>
<p>It is requested the &REGISTRAR; add the extension's namespaces
and schemas to appropriate XMPP registries.</p>
</section1>
<section1 topic='XML Schemas' anchor='schema'>
<section2 topic='Extension Schema' anchor='schema-sl'>
<p>
<code><![CDATA[
<?xml version='1.0' encoding='UTF-8'?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="urn:xmpp:sec-label:0"
xmlns="urn:xmpp:sec-label:0" elementFormDefault="qualified">
@ -769,13 +745,16 @@ And by opposing end them?
</xs:complexType>
</xs:element>
</xs:schema>
]]></code> A copy of this schema is available at <link
url="http://www.xmpp.org/schemas/sec-label.xsd">
http://www.xmpp.org/schemas/sec-label.xsd</link>. </p>
</section2>
<section2 topic="&lt;catalog/&gt; schema" anchor="schema-catalog">
<p>
<code><![CDATA[
]]></code>
A copy of this schema is available at
<link url='http://www.xmpp.org/schemas/sec-label.xsd'>
http://www.xmpp.org/schemas/sec-label.xsd</link>.
</p>
</section2>
<section2 topic='&lt;catalog/&gt; schema' anchor='schema-catalog'>
<p>
<code><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:sl="urn:xmpp:sec-label:0"
xmlns="urn:xmpp:sec-label:catalog:2" targetNamespace="urn:xmpp:sec-label:catalog:1"
@ -863,13 +842,16 @@ And by opposing end them?
</xs:complexType>
</xs:element>
</xs:schema>
]]></code> A copy of this schema is available at <link
url="http://www.xmpp.org/schemas/sec-label-catalog.xsd">
http://www.xmpp.org/schemas/sec-label-catalog.xsd</link>. </p>
</section2>
<section2 topic="&lt;esssecuritylabel/&gt; schema" anchor="schema-ess">
<p>
<code><![CDATA[
]]></code>
A copy of this schema is available at
<link url='http://www.xmpp.org/schemas/sec-label-catalog.xsd'>
http://www.xmpp.org/schemas/sec-label-catalog.xsd</link>.
</p>
</section2>
<section2 topic='&lt;esssecuritylabel/&gt; schema' anchor='schema-ess'>
<p>
<code><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="urn:xmpp:sec-label:ess:0"
xmlns="urn:xmpp:sec-label:ess:0" elementFormDefault="qualified">
@ -885,9 +867,12 @@ And by opposing end them?
</xs:annotation>
</xs:element>
</xs:schema>
]]></code> A copy of this schema is available at <link
url="http://www.xmpp.org/schemas/sec-label-ess.xsd">
http://www.xmpp.org/schemas/sec-label-ess.xsd</link>. </p>
</section2>
</section1>
]]></code>
A copy of this schema is available at
<link url='http://www.xmpp.org/schemas/sec-label-ess.xsd'>
http://www.xmpp.org/schemas/sec-label-ess.xsd</link>.
</p>
</section2>
</section1>
</xep>