Re: [PATCH v10 2/7] KEYS: trusted: allow use of kernel RNG for key material

Ahmad Fatoum
2022-05-17T17:53:38Z

Hello Jason,

On 17.05.22 19:27, Jason A. Donenfeld wrote:
> On Fri, May 13, 2022 at 04:57:00PM +0200, Ahmad Fatoum wrote:
>> + trusted.rng= [KEYS]
>> + Format: <string>
>> + The RNG used to generate key material for trusted keys.
>> + Can be one of:
>> + - "kernel"
>> + - the same value as trusted.source: "tpm" or "tee"
>> + - "default"
>> + If not specified, "default" is used. In this case,
>> + the RNG's choice is left to each individual trust source.
>> +
>
> As a general mechanism, I object to this. The kernel's RNG must be
> trusted in the first place for key material. That's the whole point of
> it.
>
> However, it sounds like you're not proposing a general mechanism, but
> just something particular to this "trusted keys" business.

The two currently upstream trust sources (trusted key backends) each provide
their own RNG callback. This series adds a third backend that uses kernel RNG
and additionally provides users of the two existing trust sources the option
to benefit from kernel RNG as well.

> this should be a module flag, and thus not documented here, but rather
> some place namespaced to your trusted keys stuff. "trusted_keys.preferred_rng={whatever}"

The trusted keys module is trusted.ko and directly before my added lines is
the trusted.source= documentation, so I think this is already at the correct place.

Thanks,
Ahmad

>
> Jason
>

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