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From Colm O hEigeartaigh <cohei...@apache.org>
Subject Re: XML Security Java 1.5.0-RC1 available
Date Tue, 20 Dec 2011 16:36:41 GMT
What we could do is add some functionality that checks that each
(local) Reference URI in a Signature is in the document tree and is
unique. The retrieved element could be set on IdResolver. This way,
the tree is only walked once, instead of each time IdResolver is
called when resolving a reference, as is the case for 1.4.x. This
behaviour could be controlled by a property, possibly defaulting to
true.
It would not check for duplicate Ids in other namespaces (e.g.
wsu:Id), or support retrieving elements in these namespaces - it would
be up to the calling code to support this.

Would this address your concerns?

Colm.

On Tue, Dec 20, 2011 at 4:21 PM, Cantor, Scott <cantor.2@osu.edu> wrote:
> On 12/20/11 11:12 AM, "Sean Mullan" <sean.mullan@oracle.com> wrote:
>>
>>The code does still call DOM Document.getElementById, but how does that
>>make it possible to do an attack?
>
> If you mark "known" ID attributes as IDs by calling setIdAtribute, Xerces
> will allow duplicates. If you insist that the application do a tree walk
> to prevent duplicates, then you're telling us that every app should
> implement the thing you claim is too slow for Santuario to implement.
>
> Additionally, parsers have bugs enforcing uniqueness on IDs during schema
> validation. Xerces-C for example has a nasty one involving wildcards and
> lax schemas. All because they allow something that shouldn't ever be legal
> in the first place, duplicates in the Document's ID map. Fix that, in one
> place, and all of this goes away.
>
> Thus my point. The Xerces team is wrong. Somebody needs to explain that to
> them, somebody they'll listen to.
>
>> The trusted validation code should be
>>creating the Document and registering the IDs. If you are letting
>>untrusted code create the Document for you and register arbitrary IDs,
>>then that is a bug.
>
> If you claim schema validation is "one way", then the parser has to be
> trusted. Alternatively, the application can't just register the IDs, but
> must also track and search for duplicates, or it can't rely on
> setIdAttributeNS to register them.
>
> That's why I'm asking about the algorithm. You're basically duplicating
> the DOM3 ID API in Santuario. So my advice is to stop relying on the
> original. Since I don't think that's really a good thing either, I
> continue to argue that the fix belongs in the parser.
>
> -- Scott
>



-- 
Colm O hEigeartaigh

Talend Community Coder
http://coders.talend.com

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