Re: [PATCH 1/1] arm64: syscall: Direct PRNG kstack randomization

[Kees Cook]

On Thu, Mar 07, 2024 at 12:10:34PM +0100, Arnd Bergmann wrote:
> For the strength, we have at least four options:
> 
> - strong rng, most expensive
> - your new prng, less strong but somewhat cheaper and/or more
>   predictable overhead
> - cycle counter, cheap but probably even less strong,
>   needs architecture code.

Are the low bits of a cycler counter really less safe than a
deterministic pRNG?

> - no rng, no overhead and no protection.

For the pRNG, why not just add a reseed timer or something that'll
happen outside the syscall window, if that's the concern about reseeding
delay? (In which case, why not continue to use the strong rng?)

-- 
Kees Cook