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Subject: Re: [PATCH] security: Fix IMA Kconfig for dependencies on ARM64
From:   Mimi Zohar <zohar@linux.vnet.ibm.com>
To:     Jason Gunthorpe <jgg@ziepe.ca>, Jiandi An <anjiandi@codeaurora.org>
Cc:     dmitry.kasatkin@gmail.com, jmorris@namei.org, serge@hallyn.com,
        linux-integrity@vger.kernel.org,
        linux-ima-devel@lists.sourceforge.net,
        linux-ima-user@lists.sourceforge.net,
        linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Wed, 07 Mar 2018 13:55:53 -0500
In-Reply-To: <20180307185132.GA30102@ziepe.ca>
References: <1520400386-17674-1-git-send-email-anjiandi@codeaurora.org>
         <20180307185132.GA30102@ziepe.ca>
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On Wed, 2018-03-07 at 11:51 -0700, Jason Gunthorpe wrote:
> On Tue, Mar 06, 2018 at 11:26:26PM -0600, Jiandi An wrote:
> > TPM_CRB driver is the TPM support for ARM64.  If it
> > is built as module, TPM chip is registered after IMA
> > init.  tpm_pcr_read() in IMA driver would fail and
> > display the following message even though eventually
> > there is TPM chip on the system:
> > 
> > ima: No TPM chip found, activating TPM-bypass! (rc=-19)
> > 
> > Fix IMA Kconfig to select TPM_CRB so TPM_CRB driver is
> > built in kernel and initializes before IMA driver.
> > 
> > Signed-off-by: Jiandi An <anjiandi@codeaurora.org>
> >  security/integrity/ima/Kconfig | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
> > index 35ef693..6a8f677 100644
> > +++ b/security/integrity/ima/Kconfig
> > @@ -10,6 +10,7 @@ config IMA
> >  	select CRYPTO_HASH_INFO
> >  	select TCG_TPM if HAS_IOMEM && !UML
> >  	select TCG_TIS if TCG_TPM && X86
> > +	select TCG_CRB if TCG_TPM && ACPI
> >  	select TCG_IBMVTPM if TCG_TPM && PPC_PSERIES
> >  	help
> >  	  The Trusted Computing Group(TCG) runtime Integrity
> 
> This seems really weird, why are any specific TPM drivers linked to
> IMA config, we have lots of drivers..
> 
> I don't think I've ever seen this pattern in Kconfig before?

As you've seen by the current discussions, the TPM driver needs to be
initialized prior to IMA.  Otherwise IMA goes into TPM-bypass mode.
 That implies that the TPM must be builtin to the kernel, and not as a
kernel module.

Mimi