Re: TPM selftest failure in 4.15

Jarkko Sakkinen
2018-02-15T12:12:42Z

On Fri, Feb 09, 2018 at 12:47:10PM +0100, Alexander Steffen wrote:
> On 09.02.2018 11:02, Jarkko Sakkinen wrote:
> > On Thu, Feb 08, 2018 at 09:02:00AM -0800, James Bottomley wrote:
> > > There is an identified regression: the TPM driver will now periodically
> > > fail to attach. However, there's no point reviewing until we agree
> > > what the fix is. I was just waiting to verify this fixed my problem
> > > (which means seeing the messages it spits out proving the TPM has
> > > remained in self test). I have now seen this and the driver still
> > > works, so I can submit a formal patch.
> >
> > For the self-test the duration falls down to 2 seconds as the specs do
> > not contain any well-defined duration for it, or at least I haven't
> > found it.
> >
> > I see three alternative ways the fix the self-test:
> >
> > 1. Execute self-test with fullTest = YES.
>
> I had proposed some fixes in this direction last year:
> https://patchwork.kernel.org/patch/10105483/
> https://patchwork.kernel.org/patch/10130535/
>
> Those combine the fast test execution with fullTest = NO for spec-compliant
> TPMs with a fallback to fullTest = YES.

The first was accepted.

The 2nd wasn't accpeted mainly for reasons that for me only acceptable
dependency is:

1. Patch that is part of the same patch set.
2. A merged commit.

I didn't event look at the code for the second one at that point because
it was formally done wrong.

What it is doing would be acceptable for me. I still think that TPM
should be fully tested before letting IMA for example to use it.

/Jarkko