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Subject: Re: [PATCH v12 1/8] x86/cet/ibt: Add Kconfig option for user-mode
 Indirect Branch Tracking
To:     Yu-cheng Yu <yu-cheng.yu@intel.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org, linux-mm@kvack.org,
        linux-arch@vger.kernel.org, linux-api@vger.kernel.org,
        Arnd Bergmann <arnd@arndb.de>,
        Andy Lutomirski <luto@kernel.org>,
        Balbir Singh <bsingharora@gmail.com>,
        Borislav Petkov <bp@alien8.de>,
        Cyrill Gorcunov <gorcunov@gmail.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Eugene Syromiatnikov <esyr@redhat.com>,
        Florian Weimer <fweimer@redhat.com>,
        "H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Kees Cook <keescook@chromium.org>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Nadav Amit <nadav.amit@gmail.com>,
        Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
        Peter Zijlstra <peterz@infradead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
        Dave Martin <Dave.Martin@arm.com>,
        Weijiang Yang <weijiang.yang@intel.com>
References: <20200918192312.25978-1-yu-cheng.yu@intel.com>
 <20200918192312.25978-2-yu-cheng.yu@intel.com>
From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <ce2524cc-081b-aec9-177a-11c7431cb20d@infradead.org>
Date:   Fri, 18 Sep 2020 13:24:13 -0700
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Hi,

If you do another version of this:

On 9/18/20 12:23 PM, Yu-cheng Yu wrote:
> Introduce Kconfig option X86_INTEL_BRANCH_TRACKING_USER.
> 
> Indirect Branch Tracking (IBT) provides protection against CALL-/JMP-
> oriented programming attacks.  It is active when the kernel has this
> feature enabled, and the processor and the application support it.
> When this feature is enabled, legacy non-IBT applications continue to
> work, but without IBT protection.
> 
> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
> ---
> v10:
> - Change build-time CET check to config depends on.
> 
>  arch/x86/Kconfig | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 6b6dad011763..b047e0a8d1c2 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1963,6 +1963,22 @@ config X86_INTEL_SHADOW_STACK_USER
>  
>  	  If unsure, say y.
>  
> +config X86_INTEL_BRANCH_TRACKING_USER
> +	prompt "Intel Indirect Branch Tracking for user-mode"
> +	def_bool n
> +	depends on CPU_SUP_INTEL && X86_64
> +	depends on $(cc-option,-fcf-protection)
> +	select X86_INTEL_CET
> +	help
> +	  Indirect Branch Tracking (IBT) provides protection against
> +	  CALL-/JMP-oriented programming attacks.  It is active when
> +	  the kernel has this feature enabled, and the processor and
> +	  the application support it.  When this feature is enabled,
> +	  legacy non-IBT applications continue to work, but without
> +	  IBT protection.
> +
> +	  If unsure, say y

	  If unsure, say y.

> +
>  config EFI
>  	bool "EFI runtime service support"
>  	depends on ACPI
> 


-- 
~Randy