On Tue, Jul 3, 2018 at 6:15 AM, Andrea Arcangeli <aarca...@redhat.com> wrote: > Hello, > > On Mon, Jul 02, 2018 at 09:52:08PM +0800, Peng Tao wrote: >> I think we can write some host generated random seeds to guest's >> urandom device, when cloning VMs from the same template before handing >> it to users. Is it enough or do you think there are more to do w/ >> re-randomizing? > > That may be enough, but it's critically important to get > right. Reusing the same /dev/urandom number just twice on two > different operations, can lead to leak of the entire private key even > if the reused random number itself is not predictable. > > You may want to look into the upstream random number generator that > can be configured at build time to printk() a warning if it's being > used at boot before it had its "shutdown" state restored. It would > sound safer if you could re-trigger such warning post vmrestore of a > cloned image if userland uses random number before the random number > has been re-seeded post vmrestore. With a full loaded userland running > immediately post vmrestore, an userland race condition would otherwise > risk to go unnoticed. > Good point! Thanks a lot!
Cheers, Tao