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Subject: Re: [PATCH] kexec_buffer measure
From:   Mimi Zohar <zohar@linux.ibm.com>
To:     Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
        Casey Schaufler <casey@schaufler-ca.com>,
        prakhar srivastava <prsriva02@gmail.com>
Cc:     linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-security-module <linux-security-module@vger.kernel.org>,
        Paul Moore <paul@paul-moore.com>,
        John Johansen <john.johansen@canonical.com>
Date:   Fri, 03 May 2019 10:24:49 -0400
In-Reply-To: <5490e443-b3ea-876e-a6b3-6a91005afe61@I-love.SAKURA.ne.jp>
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On Fri, 2019-05-03 at 09:53 +0900, Tetsuo Handa wrote:
> On 2019/05/03 1:28, Casey Schaufler wrote:
> > On 5/2/2019 8:48 AM, Mimi Zohar wrote:
> >> [Cc'ing Paul, John, Casey]
> >>
> >> On Mon, 2019-04-22 at 20:18 -0400, Mimi Zohar wrote:
> >>> [Cc'ing LSM mailing list]
> >>>
> >>> On Fri, 2019-04-19 at 17:30 -0700, prakhar srivastava wrote:
> >>>
> >>>> 2) Adding a LSM hook
> >>>> We are doing both the command line and kernel version measurement in IMA.
> >>>> Can you please elaborate on how this can be used outside of the scenario?
> >>>> That will help me come back with a better design and code. I am
> >>>> neutral about this.
> >>> As I said previously, initially you might want to only measure the
> >>> kexec boot command line, but will you ever want to verify or audit log
> >>> the boot command line hash? Perhaps LSMs would be interested in the
> >>> boot command line. Should this be an LSM hook?
> >>   From an LSM perspective, is there any interest in the boot command line?
> > 
> > I can imagine an LSM that cares about the command line,
> > but I don't have interest in it for any work I have in progress.
> > 
> 
> Since the kernel command line controls which LSMs to enable, I doubt that
> an LSM which cares about the command line can detect that the kernel command
> line was tampered when the kernel command line was tampered...

As the subject line indicates, this is the kexec boot command line.

This wouldn't be any different than the existing
kernel_read_file_from_fd() and security_kernel_load_data() calls in
kernel/kexec_file.c and  kernel/kexec.c, which provides the LSMs an
opportunity to comment on the kexec image and initramfs.

Mimi