linux-kernel - Re: [PATCH 5/5] Documentation/x86: Add CET description

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Date:   Fri, 8 Jun 2018 17:10:13 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Yu-cheng Yu <yu-cheng.yu@...el.com>, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-mm@...ck.org,
        linux-arch@...r.kernel.org, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H.J. Lu" <hjl.tools@...il.com>,
        Vedvyas Shanbhogue <vedvyas.shanbhogue@...el.com>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...capital.net>,
        Jonathan Corbet <corbet@....net>,
        Oleg Nesterov <oleg@...hat.com>, Arnd Bergmann <arnd@...db.de>,
        Mike Kravetz <mike.kravetz@...cle.com>
Subject: Re: [PATCH 5/5] Documentation/x86: Add CET description

On 06/07/2018 07:35 AM, Yu-cheng Yu wrote:
> Explain how CET works and the noshstk/noibt kernel parameters.
> 
> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@...el.com>
> ---
>  Documentation/admin-guide/kernel-parameters.txt |   6 +
>  Documentation/x86/intel_cet.txt                 | 161 ++++++++++++++++++++++++
>  2 files changed, 167 insertions(+)
>  create mode 100644 Documentation/x86/intel_cet.txt
> 

> diff --git a/Documentation/x86/intel_cet.txt b/Documentation/x86/intel_cet.txt
> new file mode 100644
> index 000000000000..1b902a6c49f4
> --- /dev/null
> +++ b/Documentation/x86/intel_cet.txt
> @@ -0,0 +1,161 @@
> +-----------------------------------------
> +Control Flow Enforcement Technology (CET)
> +-----------------------------------------
> +
> +[1] Overview
> +
> +Control Flow Enforcement Technology (CET) provides protection against
> +return/jump-oriented programing (ROP) attacks.  It can be implemented to

                        programming

> +protect both the kernel and applications.  In the first phase, only the
> +user-mode protection is implemented for the 64-bit kernel.  Thirty-two bit
> +applications are supported under the compatibility mode.
> +
> +CET includes shadow stack (SHSTK) and indirect branch tracking (IBT) and
> +they are enabled from two kernel configuration options:
> +
> +  INTEL_X86_SHADOW_STACK_USER, and

no comma.

> +  INTEL_X86_BRANCH_TRACKING_USER.
> +
> +There are two command-line options for disabling CET features:
> +
> +  noshstk - disables shadow stack, and
> +  noibt - disables indirect branch tracking.
> +
> +At run time, /proc/cpuinfo shows the availability of SHSTK and IBT.
> +

[snip]


thanks,
-- 
~Randy