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Subject: Re: [PATCH] x86/ima: require signed kernel modules
From:   Mimi Zohar <zohar@linux.ibm.com>
To:     Seth Forshee <seth.forshee@canonical.com>
Cc:     linux-integrity@vger.kernel.org,
        linux-security-module@vger.kernel.org,
        linux-kernel@vger.kernel.org, Jessica Yu <jeyu@kernel.org>,
        Luis Chamberlain <mcgrof@kernel.org>,
        David Howells <dhowells@redhat.com>,
        Justin Forbes <jforbes@redhat.com>,
        Matthew Garrett <mjg59@google.com>
Date:   Tue, 05 Feb 2019 13:52:21 -0500
In-Reply-To: <20190205183201.GA3218@ubuntu-xps13>
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         <20190205151859.GD16362@ubuntu-xps13>
         <1549385244.4146.148.camel@linux.ibm.com>
         <20190205183201.GA3218@ubuntu-xps13>
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On Tue, 2019-02-05 at 12:32 -0600, Seth Forshee wrote:
> On Tue, Feb 05, 2019 at 11:47:24AM -0500, Mimi Zohar wrote:
> > Hi Seth,
> > 
> > On Tue, 2019-02-05 at 09:18 -0600, Seth Forshee wrote:
> > > On Thu, Jan 31, 2019 at 02:18:59PM -0500, Mimi Zohar wrote:
> > > > Require signed kernel modules on systems with secure boot mode enabled.
> > > > 
> > > > To coordinate between appended kernel module signatures and IMA
> > > > signatures, only define an IMA MODULE_CHECK policy rule if
> > > > CONFIG_MODULE_SIG is not enabled.
> > > > 
> > > > This patch defines a function named set_module_sig_required() and renames
> > > > is_module_sig_enforced() to is_module_sig_enforced_or_required().  The
> > > > call to set_module_sig_required() is dependent on CONFIG_IMA_ARCH_POLICY
> > > > being enabled.
> > > > 
> > > > Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
> > > 
> > > With respect to interactions with the kernel lockdown patches, this
> > > looks better than the patches I saw previously. I don't feel like I know
> > > enough about what's going on with IMA to ack the patch, but I feel
> > > confident that it's at least not going to break signature enforcement
> > > for us.
> > 
> > Thank you for testing!  Could this be translated into a "tested-by"
> > "(for w/lockdown patches)"?
> 
> Yeah, that's fine. To be clear about what I tested, I've confirmed that
> it doesn't interfere with requiring signed modules under lockdown with
> CONFIG_IMA_ARCH_POLICY=n and IMA appraisal enabled.
> 
> Tested-by: Seth Forshee <seth.forshee@canonical.com>

Oh!  You've disabled the coordination of the two signature
verification methods.  Any chance you could test with
"CONFIG_IMA_ARCH_POLICY" enabled?

Mimi