linux-kernel - Re: [patch V2 27/28] x86/speculation: Add seccomp Spectre v2 user space protection mode

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Message-ID: <6b6f1cdc-6751-a286-3c52-740efc90192f@infradead.org>
Date:   Sun, 25 Nov 2018 11:35:35 -0800
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Jiri Kosina <jkosina@...e.cz>,
        Tom Lendacky <thomas.lendacky@....com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Casey Schaufler <casey.schaufler@...el.com>,
        Asit Mallick <asit.k.mallick@...el.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Jon Masters <jcm@...hat.com>,
        Waiman Long <longman9394@...il.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Dave Stewart <david.c.stewart@...el.com>,
        Kees Cook <keescook@...omium.org>
Subject: Re: [patch V2 27/28] x86/speculation: Add seccomp Spectre v2 user
 space protection mode

Hi,

Can you alter this without publishing a v3?
(see below)

On 11/25/18 10:33 AM, Thomas Gleixner wrote:
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -4241,9 +4241,16 @@
>  				  per thread.  The mitigation control state
>  				  is inherited on fork.
>  
> +			seccomp
> +				- Same as "prctl" above, but all seccomp
> +				  threads will enable the mitigation unless
> +				  they explicitly opt out.
> +
>  			auto    - Kernel selects the mitigation depending on
>  				  the available CPU features and vulnerability.
> -				  Default is prctl.
> +
> +			Default mitigation:
> +			If CONFIG_SECCOMP=y "seccomp", otherwise "prctl"

			If CONFIG_SECCOMP=y then "seccomp", otherwise "prctl".

>  
>  			Not specifying this option is equivalent to
>  			spectre_v2_user=auto.

g'day.
-- 
~Randy