On 06/10/2010 08:50 PM, Herbert Poetzl wrote: >> Essentially - if it is not safe to do this between the host and >> a guest, how come it is safe to do between guests? > > because the host (context) has all priviledges and > can manipulate all the guests (and usually their filesystem > without any restriction) > > so, the danger is not that the guest will modify a host > binary and use that for some kind of exploit, the danger > is more that you accidentially drop the required security > mechanisms while accessing those files (from the host) > and the guest could exploit this to mess with the host > binaries ... or it could simply mess up the guest by > involuntarily changing guest files (along with host changes) What exactly are you referring to with "security mechanisms" in this context? > the guests are all limited in their capabilities and will > not be able to do such things, but the host context is not > limited at all, i.e. everything goes :) I get that, I'm just curious how sharing a hard-link between host and guest could be used to compromise the host. At the moment, I cannot quite see the attack vector. > besides that, having a few hundred megabytes of host > files/binaries are usually acceptable ... A few hundred MB of disk space isn't a big issue. A few hundred MB of RAM, however, is - I'm trying to implement something on a very low power machine (N450 Atom, has to be passively cooled) which is limited to 2GB of RAM, and I need to deploy about 3-4VMs in it. Hence why I am trying to scrape a bit more off the bottom of the barrel. :) Gordan