[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] Re: Xen Security meeting summary
David Lie wrote: > This was an interesting discussion. I must be missing something > though: > > - page mapping visibility: several people said that they felt > uncomfortable with the global visibility of mappings from machine to > physical address in a guest as this provides a lot of information to > an attacker. > > How does letting an attacker know the physical to machine mappings > benefit an attacker? I assume the attacker still would not have > read/write access to pages that do not belong to the compromised > domain. Is there a concrete attack that people are aware of, or is > this just a precautionary measure? > > Thanks, > > David Lie The concern here was that we not give an attacker any more information than necessary for the proper functioning of the system. As you correctly noted, each domain's pages are protected from access by other domains (modulo a small number of shared pages). However, should there be a bug in this protection that did allow some unauthorized cross-domain access, knowing the physical pages used by other domains would increase the capabilities of an attacker (over random page scribbling). And though it wasn't the motivation for the concern, removing such global visibility also has the benefit of limiting one type of covert channel. So the thinking was that if we could remove these other domain mappings without significant changes or disruptions then it is beneficial to do so. Joseph Cihula (Linux) Software Security Architect Intel Corp. *** These opinions are not necessarily those of my employer *** ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_ide95&alloc_id396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/xen-devel
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