From: Nathan Lynch <nathanl@linux.ibm.com>
To: Andrew Donnellan <ajd@linux.ibm.com>
Cc: paul@paul-moore.com, nayna@linux.ibm.com, jmorris@namei.org,
linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org, gcwilson@linux.ibm.com,
linuxppc-dev@lists.ozlabs.org, serge@hallyn.com
Subject: Re: [PATCH v2 2/2] powerpc/rtas: block error injection when locked down
Date: Wed, 28 Sep 2022 11:23:08 -0500 [thread overview]
Message-ID: <87y1u3pixf.fsf@linux.ibm.com> (raw)
In-Reply-To: <591a3e016605181e119496992027ae21700a2c3b.camel@linux.ibm.com>
Andrew Donnellan <ajd@linux.ibm.com> writes:
> On Mon, 2022-09-26 at 08:16 -0500, Nathan Lynch wrote:
>> The error injection facility on pseries VMs allows corruption of
>> arbitrary guest memory, potentially enabling a sufficiently
>> privileged
>> user to disable lockdown or perform other modifications of the
>> running
>> kernel via the rtas syscall.
>>
>> Block the PAPR error injection facility from being opened or called
>> when locked down.
>>
>> Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
>
> Is there any circumstance (short of arbitrary code execution etc) where
> the rtas_call() check will actually trigger rather than the sys_rtas()
> check? (Not that it matters, defence in depth is good.)
Fair question! There are no in-kernel users of rtas_call() that pass the
error injection tokens as far as I could tell. Nor am I aware of any
out-of-tree users, for that matter. But rtas_call() is the likely most
appropriate place to have the lockdown gate should that situation change
(as it might, see https://github.com/ibm-power-utilities/librtas/issues/29).
next prev parent reply other threads:[~2022-09-28 16:24 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-26 13:16 [PATCH v2 0/2] powerpc/pseries: restrict error injection and DT changes when locked down Nathan Lynch
2022-09-26 13:16 ` [PATCH v2 1/2] powerpc/pseries: block untrusted device tree " Nathan Lynch
2022-09-26 22:39 ` Paul Moore
2022-09-28 9:51 ` Andrew Donnellan
2022-09-26 13:16 ` [PATCH v2 2/2] powerpc/rtas: block error injection " Nathan Lynch
2022-09-26 22:41 ` Paul Moore
2022-09-28 10:02 ` Andrew Donnellan
2022-09-28 16:23 ` Nathan Lynch [this message]
2022-10-04 13:25 ` [PATCH v2 0/2] powerpc/pseries: restrict error injection and DT changes " Michael Ellerman
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