linux-kernel - Re: [kernel-hardening] Re: [PATCH v3 3/3] SROP mitigation: Add sysctl to disable SROP protection.

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Message-ID: <CAGXu5j+QSn1bWB41xN8OM+dg+oGeJM9bKb92x9WdsX7tk1kANw@mail.gmail.com>
Date:	Wed, 9 Mar 2016 22:36:21 -0800
From:	Kees Cook <keescook@...omium.org>
To:	"kernel-hardening@...ts.openwall.com" 
	<kernel-hardening@...ts.openwall.com>
Cc:	Scott Bauer <sbauer@....utah.edu>,
	LKML <linux-kernel@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>, wmealing@...hat.com,
	Andi Kleen <ak@...ux.intel.com>,
	Andy Lutomirski <luto@...capital.net>,
	Abhiram Balasubramanian <abhiram@...utah.edu>
Subject: Re: [kernel-hardening] Re: [PATCH v3 3/3] SROP mitigation: Add sysctl
 to disable SROP protection.

On Tue, Mar 8, 2016 at 1:00 PM, One Thousand Gnomes
<gnomes@...rguk.ukuu.org.uk> wrote:
> On Tue,  8 Mar 2016 13:47:55 -0700
> Scott Bauer <sbauer@....utah.edu> wrote:
>
>> This patch adds a sysctl argument to disable SROP protection.
>
> Shouldn't it be a sysctl to enable it irrevocably, otherwise if I have DAC
> capability I can turn off SROP and attack something to get to higher
> capability levels ?
>
> (The way almost all distros are set up its kind of academic but for a
> properly secured system it might matter).

Perhaps use proc_dointvec_minmax_sysadmin instead to tie changes
strictly to CAP_SYS_ADMIN?

-Kees

>
> Alan



-- 
Kees Cook
Chrome OS & Brillo Security