linux-kernel - Re: [PATCH] x86/ima: require signed kernel modules

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Message-ID: <20190205183201.GA3218@ubuntu-xps13>
Date:   Tue, 5 Feb 2019 12:32:01 -0600
From:   Seth Forshee <seth.forshee@...onical.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>
Cc:     linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, Jessica Yu <jeyu@...nel.org>,
        Luis Chamberlain <mcgrof@...nel.org>,
        David Howells <dhowells@...hat.com>,
        Justin Forbes <jforbes@...hat.com>,
        Matthew Garrett <mjg59@...gle.com>
Subject: Re: [PATCH] x86/ima: require signed kernel modules

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@...ux.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@...onical.com>