From: Matt Parnell <mparnell@gmail.com>
To: Matthew Garrett <mjg59@google.com>
Cc: Kees Cook <keescook@chromium.org>,
LSM List <linux-security-module@vger.kernel.org>,
David Howells <dhowells@redhat.com>,
matthew.garrett@nebula.com
Subject: Re: [PATCH] Kernel Lockdown: Add an option to allow raw MSR access even, in confidentiality mode.
Date: Mon, 2 Dec 2019 20:50:45 -0600 [thread overview]
Message-ID: <b887b039-ebf6-5ef1-429e-04792f3cd664@gmail.com> (raw)
In-Reply-To: <80b97dca-6eec-b008-81aa-74eb4f14ea0b@gmail.com>
Correction: I'm out of caffeine, tired, and it has made me an idiot.
That message triggers regardless, it seems. I apologize.
On 12/2/19 8:24 PM, Matt Parnell wrote:
> For what it is worth, this doesn't happen with lockdown disabled.
>
> That message and the code that checks for mitigations is in
> arch/x86/kvm/vmx/vmx.c - for some reason locking down the MSRs is even
> making the kernel think that the MSR for the mitigation isn't there,
> meaning that it is also likely not mitigating the bug.
>
> On 12/2/19 8:16 PM, Matthew Garrett wrote:
>> On Mon, Dec 2, 2019 at 6:01 PM Matt Parnell <mparnell@gmail.com> wrote:
>>> I should also mention the kernel itself thinks it is vulnerable with the
>>> MSRs locked down:
>>>
>>> [ 7.367922] L1TF CPU bug present and SMT on, data leak possible. See
>>> CVE-2018-3646 and
>>> https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html for
>>> details.
>> The lockdown code doesn't touch any of the codepaths the kernel uses
>> to access MSRs itself (a *lot* would break in that case), so if the
>> kernel is asserting this inappropriately then that seems like a kernel
>> bug.
next prev parent reply other threads:[~2019-12-03 2:39 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-30 6:49 [PATCH] Kernel Lockdown: Add an option to allow raw MSR access even, in confidentiality mode Matt Parnell
2019-11-30 18:36 ` Kees Cook
2019-11-30 19:09 ` Matt Parnell
2019-12-01 20:53 ` Matt Parnell
2019-12-02 18:29 ` Matt Parnell
2019-12-02 22:55 ` Jordan Glover
2019-12-02 23:13 ` Matt Parnell
2019-12-02 23:29 ` Matthew Garrett
2019-12-02 23:31 ` Matt Parnell
2019-12-03 2:13 ` Matt Parnell
2019-12-03 2:16 ` Matthew Garrett
2019-12-03 2:24 ` Matt Parnell
2019-12-03 2:50 ` Matt Parnell [this message]
2019-12-03 3:57 ` Matt Parnell
2019-12-02 19:43 ` Matthew Garrett
2019-12-02 20:39 ` Matt Parnell
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