Re: [PATCH 2/3] random: rng-seed source is utf-8

From: Theodore Y. Ts'o
Date: Tue Feb 18 2020 - 12:17:01 EST

On Tue, Feb 18, 2020 at 08:01:51AM -0800, Mark Salyzyn wrote:
> I am additionally concerned about add_bootloader_randomness() because it is
> possible for it to sleep because of add_hwgenerator_randomness() as once it
> hits the entropy threshold. As-is it can not be used inside start_kernel()
> because the sleep would result in a kernel panic, and I suspect its use
> inside early_init_dt_scan_chosen() for the commit "fdt: add support for
> rng-seed" might also be problematic since it is effectively called
> underneath start_kernel() is it not?
> If add_bootloader_randomness was rewritten to call add_device_randomness()
> always, and when trusted also called the functionality of the new
> credit_trusted_entropy_bits (no longer needing to be exported if so), then
> the function could be used in both start_kernel() and
> early_init_dt_scan_chosen().

That's a good point, and it's a bug in add_bootloader_randomness().
That should be easily fixed by simply having it call mix_pool_bytes()
and credit_entropy_bits() directly. I'll create a patch...

- Ted