Re: [PATCH] KEYS: trusted: allow module init if TPM is inactive or deactivated

[Roberto Sassu]

On 7/11/2019 9:48 PM, Jarkko Sakkinen wrote:
> On Fri, Jul 05, 2019 at 06:37:35PM +0200, Roberto Sassu wrote:
> > Commit c78719203fc6 ("KEYS: trusted: allow trusted.ko to initialize w/o a
> > TPM") allows the trusted module to be loaded even a TPM is not found to
> > avoid module dependency problems.
> >
> > Unfortunately, this does not completely solve the issue, as there could be
> > a case where a TPM is found but is not functional (the TPM commands return
> > an error). Specifically, after the tpm_chip structure is returned by
> > tpm_default_chip() in init_trusted(), the execution terminates after
> > init_digests() returns -EFAULT (due to the fact that tpm_get_random()
> > returns a positive value, but less than TPM_MAX_DIGEST_SIZE).
> >
> > This patch fixes the issue by ignoring the TPM_ERR_DEACTIVATED and
> > TPM_ERR_DISABLED errors.
>
> Why allow trusted module to initialize if TPM is not functional?

According to the bug report at https://bugs.archlinux.org/task/62678,
the trusted module is a dependency of the ecryptfs module. We should
load the trusted module even if the TPM is inactive or deactivated.

Given that commit 782779b60faa ("tpm: Actually fail on TPM errors during
"get random"") changes the return code of tpm_get_random(), the patch
should be modified to ignore the -EIO error. I will send a new version.

Roberto

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