linux-kernel - Re: [PATCH 03/27] Enforce module signatures if the kernel is locked down

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Message-Id: <1509385936.3583.170.camel@linux.vnet.ibm.com>
Date:   Mon, 30 Oct 2017 13:52:16 -0400
From:   Mimi Zohar <zohar@...ux.vnet.ibm.com>
To:     David Howells <dhowells@...hat.com>
Cc:     linux-security-module@...r.kernel.org, gnomes@...rguk.ukuu.org.uk,
        linux-efi@...r.kernel.org, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org, jforbes@...hat.com,
        Matthew Garrett <mjg59@...gle.com>,
        "Bruno E. O. Meneguele" <brdeoliv@...hat.com>
Subject: Re: [PATCH 03/27] Enforce module signatures if the kernel is locked
 down

[Corrected Matthew Garrett's email address.  Cc'ed Bruno Meneguele]

On Mon, 2017-10-30 at 17:00 +0000, David Howells wrote:
> Mimi Zohar <zohar@...ux.vnet.ibm.com> wrote:
> 
> > This kernel_is_locked_down() check is being called for both the
> > original and new module_load syscalls.  We need to be able
> > differentiate them.  This is fine for the original syscall, but for
> > the new syscall we would need an additional IMA check -
> > !is_ima_appraise_enabled().
> 
> IMA can only be used with finit_module()?

Yes, without the file descriptor, IMA-appraisal can't access the
xattrs. 

You should really look at Bruno's patches, which are in my next
branch:

8168913c50d5 "ima: check signature enforcement against cmdline param instead of CONFIG"
404090509894 module: export module signature enforcement status

Can we get an Ack on the module one?

Mimi