[PATCH v1 1/2] random-bits: Factor out entropy generating function

[Jason A. Donenfeld]

Hi Christian,

Thanks for looping me into this thread.

On Wed, Mar 30, 2022 at 3:38 PM Cristian Rodríguez
<crrodriguez@opensuse.org> wrote:
>
> On Wed, Mar 30, 2022 at 1:30 PM Noah Goldstein via Libc-alpha
> <libc-alpha@sourceware.org> wrote:
>
> > Thanks, I can add patches for sparc/powerpc64le/ia64. Still feel that
> > since it takes testing and there are optimization cases that we mayf
> > want to make it's still best to have a seperate file.
>
> What is really needed is to get some sort of randomness function
> exposed through the VDSO, so there is no syscall overhead and all this
> magic can be dropped. I'm not even sure if that is possible.  that or
> a reliable prng usable even by the dynamic linker.

Can someone provide some context on this? I've actually looked into
having some megafast userspace RNG component in the vDSO, and I'm not
fundamentally opposed to the idea. I think there's interesting
potential there and something worth considering. But what's the
context of you asking for this now? Under what circumstances are you
finding that calling getrandom(0) or similar is too high overhead or
otherwise problematic?

Jason