On Dec 24, 2013, at 2:53 PM, Xin Li <[email protected]> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA512 > > On 12/24/13 14:36, Paul Hoffman wrote: >> On Dec 24, 2013, at 12:44 PM, Xin Li <[email protected]> wrote: >> >>> I think we shouldn't save entropy inside jails, as the data is >>> not going to be used by rc script (pjd@126744). If there is no >>> objections, I will commit this changeset on January 1, 2014. >> >> Even if it is not used by an rc script, it might be used by some >> userland program (running as root, of course) that knows about the >> directory and wants some fresh entropy for its own use. > > Why a userland application would want to use these? Would you mind > elaborating what kind of use that would be? I don't have a specific application in mind, and certainly not one for a jail. However, I'm not sure what the value in removing a feature for a jail if we don't know if anyone is using that feature. Thus, my question. > My understanding is that the saved entropy is used for bootstraping > the system only: any applications that wants good random numbers > should just use /dev/random because relying on something saved on disk > is the worst way for someone who wants more entropy. Quite true. Note, however, that we don't delete the saved entropy after booting and add it just before shutdown: we leave it there for some reason. I'm not sure why a jail is so different of an environment that it should be treated differently than a normal (non-jail) environment. Maybe there is a reason, but I'm not seeing it. >> Is there a problem with saving the directory in jails? It >> certainly isn't taking up much space. > > No, it's not about space. What I am concerned is that it may have > wasted entropy: each time (every */11 minute) the system would get > 2048 bytes out from /dev/random per jail. This deterministic behavior > may trigger reseeds earlier than wanted. I did not understand this. What changes in the system does removing /var/db/entropy cause? (If this is answered in a longer article, a pointer to it would be useful to me (and maybe others).) --Paul Hoffman _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-security To unsubscribe, send any mail to "[email protected]"