linux-kernel - Re: RFC: default to spec_store_bypass_disable=prctl spectre_v2

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Message-ID: <202011041411.AD961737EA@keescook>
Date:   Wed, 4 Nov 2020 14:14:07 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Andrea Arcangeli <aarcange@...hat.com>
Cc:     YiFei Zhu <zhuyifei1999@...il.com>,
        Linux Containers <containers@...ts.linux-foundation.org>,
        YiFei Zhu <yifeifz2@...inois.edu>, bpf <bpf@...r.kernel.org>,
        kernel list <linux-kernel@...r.kernel.org>,
        Aleksa Sarai <cyphar@...har.com>,
        Andy Lutomirski <luto@...capital.net>,
        David Laight <David.Laight@...lab.com>,
        Dimitrios Skarlatos <dskarlat@...cmu.edu>,
        Giuseppe Scrivano <gscrivan@...hat.com>,
        Hubertus Franke <frankeh@...ibm.com>,
        Jack Chen <jianyan2@...inois.edu>,
        Jann Horn <jannh@...gle.com>,
        Josep Torrellas <torrella@...inois.edu>,
        Tianyin Xu <tyxu@...inois.edu>,
        Tobin Feldman-Fitzthum <tobin@....com>,
        Tycho Andersen <tycho@...ho.pizza>,
        Valentin Rothberg <vrothber@...hat.com>,
        Will Drewry <wad@...omium.org>, Jiri Kosina <jikos@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Waiman Long <longman@...hat.com>
Subject: Re: RFC: default to spec_store_bypass_disable=prctl
 spectre_v2_user=prctl

On Wed, Nov 04, 2020 at 04:57:02PM -0500, Andrea Arcangeli wrote:
> Switch the kernel default of SSBD and STIBP to the ones with
> CONFIG_SECCOMP=n (i.e. spec_store_bypass_disable=prctl
> spectre_v2_user=prctl) even if CONFIG_SECCOMP=y.

Agreed. I think this is the right time to flip this switch. I agree with
the (very well described) rationales. :)

Fundamentally, likely everyone who is interested in manipulating the
mitigations are doing so now, and it doesn't make sense (on many fronts)
to tie some to seccomp mode any more (which was intended as a temporary
defense to gain coverage while sysadmins absorbed what the best
practices should be).

Thanks for sending this!

Acked-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook