From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hopwood Subject: Re: Module loading in unpriveledged domains Date: Tue, 23 Nov 2004 01:53:15 +0000 Message-ID: <41A2980B.8090506@blueyonder.co.uk> References: Reply-To: david.nospam.hopwood@blueyonder.co.uk Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: xen-devel-admin@lists.sourceforge.net Errors-To: xen-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: xen-devel@lists.sourceforge.net List-Id: xen-devel@lists.xenproject.org Ian Pratt wrote: >>Ian Pratt wrote: >> >>>>Is there any security risk in enabling loadable module support in the linux >>>>kernel used for the unpriveledged domains? I ask this question in the context of >>>>a virtual private server hosting provider. >>> >>>There shouldn't be any security risk at all -- Xen should provide >>>all the isolation you need (modulo any bugs). >> >>So the answer to the original question is, "yes, enabling loadable module >>support will increase your exposure to security risks due to any weaknesses >>in Xen's isolation." Xen hasn't had particularly extensive security review >>yet. > > I don't think that preventing loadable module support is going to > buy you anything. If your users have root they can write to the > domain's memory image and hence in practice do anything that they > could if they had kernel modules. True, unless there are bugs that cause different behaviour depending on whether a module is compiled-in or loaded (such as ). Nevertheless enabling loadable modules may allow a greater proportion of script kiddies to be capable of exploiting any given bug. This is all the same as in standard Linux, so perhaps I should have said: enable loadable modules iff you would do so in standard Linux. > Xen has been designed to provide secure isolation between > guests. It has undergone code review by a bunch of different > people. It may have security bugs, but at least they're > relatively obscure... I remain skeptical. -- David Hopwood ------------------------------------------------------- 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://productguide.itmanagersjournal.com/