Re: [PATCH] tpm: Salt tpm_get_random() result with get_random_bytes()

From: Jason Gunthorpe
Date: Tue Oct 15 2019 - 13:04:56 EST


On Tue, Oct 15, 2019 at 03:47:02PM +0300, Jarkko Sakkinen wrote:
> Salt the result that comes from the TPM RNG with random bytes from the
> kernel RNG. This will allow to use tpm_get_random() as a substitute for
> get_random_bytes(). TPM could have a bug (making results predicatable),
> backdoor or even an inteposer in the bus. Salting gives protections
> against these concerns.

Seems like a dangerous use case, why would any kernel user that cared
about quality of randomness ever call a tpm_* API to get quality
random data?

Jason