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Re: query by reference

From: Steve Harris <S.W.Harris@ecs.soton.ac.uk>
Date: Wed, 16 Nov 2005 09:25:05 +0000
To: dawg mailing list <public-rdf-dawg@w3.org>
Message-ID: <20051116092505.GC9735@login.ecs.soton.ac.uk>

On Tue, Nov 15, 2005 at 04:43:42PM -0500, Kendall Clark wrote:
> I'd like to propose adding that back to the protocol design.  
> Basically we're talking about adding another parameter (in HTTP),  
> "query-uri", the value of which would be a URI which, when  
> dereferenced, would return a representation of a SPARQL query  
> resource. That would add a third way to "convey a query" to a SPARQL  
> query service:

Sounds good to me.
 
> a. POSTing a urlencoded query in the body of an HTTP request
> b. serializing a query in a URI (in the 'query' parameter)
> c. 'pointing' at a query on the Web and asking the service to deref  
> and execute it
> 
> I don't believe this opens any additional security or implementation  
> burdens since:
> 
> - we already allow arbitrary URIs to be deref'd to load data
> 
> - whatever sanity checks one would implement (or specify) re:  
> executing an arbitrary SPARQL query conveyed via (a) or (b) also  
> apply to (c), and I don't believe (c) adds any additional constraints  
> or holes (but I'm *not* a security expert)...

I agree, but its not that simple. My understanding is that is OK by the
spec. for services not to treat FROM etc. as an instruction to load, and I
hope that publically accessible sites will, whereas a complaint impl.
would have to dereference the query-uri to find what it had to run.
However, if there is a limit of one query-uri paramter then there is a 1:1
trade in requests, which is not too much of a security issue (the attacker
may as well have issued the request to the third party itsself, it just
adds a bit of obfuscation).

PS incase anyone wonders why I'm so bothered about this, I have a vision
   of the future where SPARQL's FROM becomes the most popular vector for
   denial of service attacks... people'd really love us then.

- Steve (also *not* a security expert)
Received on Wednesday, 16 November 2005 09:25:21 GMT

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