On Fri, Jul 11, 2014 at 8:44 AM, Jason Cooper <jason@xxxxxxxxxxxxxx> wrote: > On Fri, Jul 11, 2014 at 06:56:26PM +0530, Amit Shah wrote: >> On (Wed) 09 Jul 2014 [12:07:25], Jason Cooper wrote: >> > Amit, Kees, >> >> (snip) >> >> > I'm cooling to the idea of the init function for virtio-rng, and it >> > might be best just to admit that there's no way to seed the entropy pool >> > from the virtio-rng at probe time. After all, once userspace is up, the >> > system should take advantage of /dev/hwrng for the generation of >> > long-term keys. Either via rngd feeding /dev/random, or directly. >> > >> > As for the follow-on patch you asked about, I think that's fine. More >> > entropy can't hurt. >> > >> > The below patch might be worth considering so that the user of a system >> > with only virtio-rng can kick the entropy pool as they see fit. It's >> > probably not too kosher as is, but if the idea is liked, I could clean >> > it up and submit. >> > >> > The advantage is that users don't need to have rngd installed and >> > running on the system in order to jump-start the entropy pool. >> >> ... so a udev rule that looks for the new sysfs file, and asks the >> kernel to do its thing? > > Or, as simple as: > > [ -e /sys/.../rng_seed_kernel ] && echo "0" >/sys/.../rng_seed_kernel > > in the initrd. It needs to run *before* any init scripts which may create > keys. > >> And maybe even a patch to rngd that looks for this file and does a >> similar thing? > > I'm not opposed to that, but it doesn't fit the problem I'm trying to > solve. Basically, average systems, not trying to be Ft Knox-secure, but > needing to generate long-term keys at first boot. These systems won't > have an hwrng installed, but should use one if available. eg > virtio-rng, or any of the on-die SoC hwrngs. > >> There's also the option to use a delayed workqueue item, that will >> succeed if probe has finished. This method doesn't have userspace >> dependencies. > > Hmm, I like that idea better. No ABI change to maintain, no userspace > changes... You obviously know virtio-rng better than I do, care to take > a crack at it? I like this idea too. It's much nicer to just have the kernel Do The Right Thing automatically. :) -Kees -- Kees Cook Chrome OS Security _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
