OASIS eXtensible Access Control Markup Language (XACML) TC

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Re: [xacml] Comment on hierarchical Resource

  • 1.  Re: [xacml] Comment on hierarchical Resource

    Posted 06-02-2004 14:41
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    Subject: Re: [xacml] Comment on hierarchical Resource


    
    
    
    
    Hi, Anne
    
    >I agree with this.
    >The most recent working draft attached to
    >http://lists.oasis-open.org/archives/xacml/200405/msg00104.html
    >does not attempt to re-define xpath-node-match.  It merely refers
    >to the existing definition.
    
    OK. I am not clear on the sentence that "This function MAY be used with the
    higher-order bag functions described in Appendix A.3.12". In my
    understanding, this function only returns Boolean and nothing to do with
    bag. Or I miss something?
    
    
    >It seems straightforward to implement, would need to be
    >calculated only if the policy actually uses one of these
    >Attributes, and would allow XACML implementations that do not
    >support XPath expressions to express some useful policies with
    >respect to XML documents.
    
    This slipped out of my head. So you want to specify policy for XML
    documents without XPath support. Correct?
    If so, resource-ancestor etc. would be useful.
    
    >Would it be OK if I define a new Resource AttributeId for this
    >called "document-id" with type anyURI?  This new Attribute would
    >be specified as containing the URI of the entire document of
    >which the requested resource is a part.  This seems more clear to me.
    
    Since "http://medico.com/medicalrec/Bert"; is meta info of the embedded XML
    doc, then it might be appropriate to create a new attribute for this like
    "document-id" as you wrote. I reconsider this.
    
    >You did not describe "anyURI-path-match" above.  Why can't this
    >function be part of "anyURI-match" with Tim's proposed "*"
    >wildcard character?
    
    I did not read Tim's proposal. I will comment after I read it.
    
    Best,
    Michiharu
    
    
                                                                               
                 Anne Anderson                                                 
                 <Anne.Anderson@Su                                             
                 n.COM>                                                     To 
                                           XACML TC                            
                 2004/06/02 02:49          <xacml@lists.oasis-open.org>        
                                                                            cc 
                                                                               
                 Please respond to                                     Subject 
                   Anne.Anderson           Re: [xacml] Comment on hierarchical 
                                           Resource                            
                                                                               
                                                                               
                                                                               
                                                                               
                                                                               
                                                                               
    
    
    
    
    On 2 June, Michiharu Kudoh writes: [xacml] Comment on hierarchical Resource
     > The following is my comment on hierarchical resource.
     >
     > - 7.13.2 xpath-node-match function
     >
     > While the definition of this function in 1.0 is that the input is two
    xpath
     > expressions and the output is boolean value, the definition in the
    working
     > draft on hierarchical resources for XACML 2.0 is that the input is one
     > xpath expression and the output is applied node(s). I would prefer the
     > original definition. I want to avoid to deal with "node" as a primitive
     > data type of XACML because it is an implemenation-specific data type. It
    is
     > different from other data types like integer and URI. If we remains the
     > function definition as is, XACML spec does not have to worry about how
    to
     > define node of XML documents.
    
    I agree with this.
    
    The most recent working draft attached to
    http://lists.oasis-open.org/archives/xacml/200405/msg00104.html
    does not attempt to re-define xpath-node-match.  It merely refers
    to the existing definition.
    
     > - 7.13.2 resource-ancestor and resource-parent
     >
     > Resource-ancestor and resource-parent will not be used in the case of
    XML
     > document.
    
    Why not?
    
    It seems straightforward to implement, would need to be
    calculated only if the policy actually uses one of these
    Attributes, and would allow XACML implementations that do not
    support XPath expressions to express some useful policies with
    respect to XML documents.
    
     > - resource-id
     >
     > As I wrote in my previous email, I would prefer to specify two
    resource-id
     > attribute with different data types in one request context in the case
    of
     > XML document. For example, if the user accesses of BoD element
     > (/md:record/md:patient/md:BoD) of XML document of
     > http://medico.com/medicalrec/Bert, the request context would have the
     > following two resource-id attributes:
     >
     > resource-id of http://medico.com/medicalrec/Bert with datatype anyURI
     > (optional)
     > resource-id of /md:record/md:patient/md:BoD with datatype
    xpath-expression
     >
     > The corresponding policy would be:
     >
     > if resource-id of anyURI data type is "http://medico.com/medicalrec/Bert
    "
     > and resource-id of xpath-expression data type matches to
     > "/md:record/md:patient" the access is allowed.
     >
     > Resource-id with any URI data type can be omitted as I wrote before. For
     > example, if policy does not need to check URI, then xpath-expression
    match
     > checking is enough. The combination of anyURI and xpath still means that
     > the target resource is a single node.
     >
     > Therefore, the request context can have two or more resource-ids if they
     > have different data types. (There is a way of passing them to PDP in one
     > string using XPointer (as specified in 1.0) though.)
     >
     > It may contradict the description of 7.[A] requests for multiple
    resources.
     > Thus, in the case of XML document, I think "scope" attribute should be
     > applied to resource-id of xpath-expression data type. It is clear enough
    if
     > this semantics is specified in the profile document.
    
    If the request is for only a portion of the XML document
    http://medico.com/medicalrec/Bert, then it seems incorrect to me
    to say the resource-id is "http://medico.com/medicalrec/Bert"; -
    that resource-id identifies the entire XML document and not just
    the requested portion of it.
    
    Would it be OK if I define a new Resource AttributeId for this
    called "document-id" with type anyURI?  This new Attribute would
    be specified as containing the URI of the entire document of
    which the requested resource is a part.  This seems more clear to
    me.
    
     > - 7.13.2 anyURI-equal/match function
     >
     > I would like to see the definition of anyURI-match function that
    receives
     > two anyURI values and returns true
     > if "scheme" exists, then the scheme of the first argument and the scheme
    of
     > the second argument must be the same
     > if "authority" exists, then the authority of the first argument and the
     > authority of the second argument must be the same
     > if "path" exists, then the path of the first argument must be equal or
    the
     > subset of the second argument.
     >
     > For example,
     > anyURI-match(http://abc, http://abc) SHALL return true
     > anyURI-match(//abc, //abc) SHALL return true
     > anyURI-match(/x/y/z, /x/y/z) SHALL return true
     > anyURI-match(http://abc, //abc) SHALL return false
     > anyURI-match(//abc, /x/y/z) SHALL return false
     >
    I do not see any conflict between these semantics and rfc2396
    (URI Generic Syntax), so I support extending "anyURI-equal" and
    "anyURI-match" as above.  Partly, this involves supporting
    matching of relative URIs as well as absolute URIs.
    
     > anyURI-path-match(/x/y, /x/y/z) SHALL return true
     > anyURI-path-match(/x/z, /x/y) SHALL return false
    
    You did not describe "anyURI-path-match" above.  Why can't this
    function be part of "anyURI-match" with Tim's proposed "*"
    wildcard character?
    
    If relative URIs are supported, then using his proposal:
    
       anyURI-match(/x/y/*, /x/y/z) SHALL return true
       anyURI-match(/x/z, /x/y) SHALL return false
    
     > Any comments are welcome.
     >
     > Best,
     > Michiharu
    
    Thank you for your comments.  Additional comments are welcome.
    
    Anne
    --
    Anne H. Anderson             Email: Anne.Anderson@Sun.COM
    Sun Microsystems Laboratories
    1 Network Drive,UBUR02-311     Tel: 781/442-0928
    Burlington, MA 01803-0902 USA  Fax: 781/442-1692
    
    
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