From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: linux-integrity@vger.kernel.org,
David Safford <david.safford@ge.com>,
Pascal Van Leeuwen <pvanleeuwen@verimatrix.com>,
James Bottomley <James.Bottomley@HansenPartnership.com>,
Peter Huewe <peterhuewe@gmx.de>, Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] tpm: Salt tpm_get_random() result with get_random_bytes()
Date: Wed, 16 Oct 2019 13:38:05 +0300 [thread overview]
Message-ID: <20191016103805.GA10184@linux.intel.com> (raw)
In-Reply-To: <20191015170450.GB5444@ziepe.ca>
On Tue, Oct 15, 2019 at 02:04:50PM -0300, Jason Gunthorpe wrote:
> 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?
This is related to this discussion:
https://lore.kernel.org/linux-integrity/CAE=NcrY3BTvD-L2XP6bsO=9oAJLtSD0wYpUymVkAGAnYObsPzQ@mail.gmail.com/T/#t
I could also move this to the call site.
/Jarkko
next prev parent reply other threads:[~2019-10-16 10:38 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-15 12:47 [PATCH] tpm: Salt tpm_get_random() result with get_random_bytes() Jarkko Sakkinen
2019-10-15 17:04 ` Jason Gunthorpe
2019-10-16 10:38 ` Jarkko Sakkinen [this message]
2019-10-16 10:43 ` Jarkko Sakkinen
2019-10-16 16:09 ` Jason Gunthorpe
2019-10-17 16:21 ` Jarkko Sakkinen
2019-10-16 7:02 ` Janne Karhunen
2019-10-16 10:41 ` Jarkko Sakkinen
2019-10-16 11:16 ` Janne Karhunen
2019-10-16 16:23 ` Jarkko Sakkinen
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