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Subject: Re: [PATCH v2] ima: add a new CONFIG for loading arch-specific
 policies
From:   Mimi Zohar <zohar@linux.ibm.com>
To:     James Bottomley <James.Bottomley@HansenPartnership.com>,
        Nayna Jain <nayna@linux.ibm.com>,
        linux-integrity@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-efi@vger.kernel.org, linux-s390@vger.kernel.org
Cc:     Ard Biesheuvel <ardb@kernel.org>,
        Philipp Rudo <prudo@linux.ibm.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        linux-kernel@vger.kernel.org
Date:   Wed, 04 Mar 2020 07:35:09 -0500
In-Reply-To: <1583307813.3907.4.camel@HansenPartnership.com>
References: <1583289211-5420-1-git-send-email-nayna@linux.ibm.com>
         <1583307813.3907.4.camel@HansenPartnership.com>
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On Tue, 2020-03-03 at 23:43 -0800, James Bottomley wrote:
> On Tue, 2020-03-03 at 21:33 -0500, Nayna Jain wrote:

> > diff --git a/security/integrity/ima/Kconfig
> > b/security/integrity/ima/Kconfig
> > index 3f3ee4e2eb0d..d17972aa413a 100644
> > --- a/security/integrity/ima/Kconfig
> > +++ b/security/integrity/ima/Kconfig
> > @@ -327,3 +327,12 @@ config IMA_QUEUE_EARLY_BOOT_KEYS
> >  	depends on IMA_MEASURE_ASYMMETRIC_KEYS
> >  	depends on SYSTEM_TRUSTED_KEYRING
> >  	default y
> > +
> > +config IMA_SECURE_AND_OR_TRUSTED_BOOT
> > +	bool
> > +	depends on IMA
> > +	depends on IMA_ARCH_POLICY
> > +	default n
> 
> You can't do this: a symbol designed to be selected can't depend on
> other symbols because Kconfig doesn't see the dependencies during
> select.  We even have a doc for this now:
> 
> Documentation/kbuild/Kconfig.select-break

The document is discussing a circular dependency, where C selects B.
 IMA_SECURE_AND_OR_TRUSTED_BOOT is not selecting anything, but is
being selected.  All of the Kconfig's are now dependent on
IMA_ARCH_POLICY being enabled before selecting
IMA_SECURE_AND_OR_TRUSTED_BOOT.

As Ard pointed out, both IMA and IMA_ARCH_POLICY are not needed, as
IMA_ARCH_POLICY is already dependent on IMA.

Mimi