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From: mark.rutland@arm.com (Mark Rutland)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 7/7] arm64: Enable CONFIG_ARM64_TTBR0_PAN
Date: Fri, 2 Sep 2016 16:47:17 +0100	[thread overview]
Message-ID: <20160902154716.GA17347@leverpostej> (raw)
In-Reply-To: <1472828533-28197-8-git-send-email-catalin.marinas@arm.com>

On Fri, Sep 02, 2016 at 04:02:13PM +0100, Catalin Marinas wrote:
> This patch adds the Kconfig option to enable support for TTBR0 PAN. The
> option is default off because of a slight performance hit when enabled,
> caused by the additional TTBR0_EL1 switching during user access
> operations or exception entry/exit code.
> 
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: James Morse <james.morse@arm.com>
> Cc: Kees Cook <keescook@chromium.org>
> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
> ---
>  arch/arm64/Kconfig | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index bc3f00f586f1..3fb9a6ce464d 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -785,6 +785,14 @@ config SETEND_EMULATION
>  	  If unsure, say Y
>  endif
>  
> +config ARM64_TTBR0_PAN
> +	bool "Priviledged Access Never using TTBR0_EL1 switching"

Minor nit/bikeshed, but could we follow the example of arch/arm's
SW_DOMAIN_PAN and call this ARM64_SW_TTRBR0_PAN, prepending "Emulate "
to the dsecription?

That makes it very clear that this is a SW feature, rather than using
the real PAN, but only on TTBR0.

Thanks,
Mark.

> +	help
> +	  Enabling this option prevents the kernel from accessing
> +	  user-space memory directly by pointing TTBR0_EL1 to a reserved
> +	  zeroed area and reserved ASID. The user access routines
> +	  restore the valid TTBR0_EL1 temporarily.
> +
>  menu "ARMv8.1 architectural features"
>  
>  config ARM64_HW_AFDBM
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

WARNING: multiple messages have this Message-ID (diff)
From: Mark Rutland <mark.rutland@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
	AKASHI Takahiro <takahiro.akashi@linaro.org>,
	Will Deacon <will.deacon@arm.com>,
	James Morse <james.morse@arm.com>,
	Kees Cook <keescook@chromium.org>,
	kernel-hardening@lists.openwall.com
Subject: [kernel-hardening] Re: [PATCH v2 7/7] arm64: Enable CONFIG_ARM64_TTBR0_PAN
Date: Fri, 2 Sep 2016 16:47:17 +0100	[thread overview]
Message-ID: <20160902154716.GA17347@leverpostej> (raw)
In-Reply-To: <1472828533-28197-8-git-send-email-catalin.marinas@arm.com>

On Fri, Sep 02, 2016 at 04:02:13PM +0100, Catalin Marinas wrote:
> This patch adds the Kconfig option to enable support for TTBR0 PAN. The
> option is default off because of a slight performance hit when enabled,
> caused by the additional TTBR0_EL1 switching during user access
> operations or exception entry/exit code.
> 
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: James Morse <james.morse@arm.com>
> Cc: Kees Cook <keescook@chromium.org>
> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
> ---
>  arch/arm64/Kconfig | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index bc3f00f586f1..3fb9a6ce464d 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -785,6 +785,14 @@ config SETEND_EMULATION
>  	  If unsure, say Y
>  endif
>  
> +config ARM64_TTBR0_PAN
> +	bool "Priviledged Access Never using TTBR0_EL1 switching"

Minor nit/bikeshed, but could we follow the example of arch/arm's
SW_DOMAIN_PAN and call this ARM64_SW_TTRBR0_PAN, prepending "Emulate "
to the dsecription?

That makes it very clear that this is a SW feature, rather than using
the real PAN, but only on TTBR0.

Thanks,
Mark.

> +	help
> +	  Enabling this option prevents the kernel from accessing
> +	  user-space memory directly by pointing TTBR0_EL1 to a reserved
> +	  zeroed area and reserved ASID. The user access routines
> +	  restore the valid TTBR0_EL1 temporarily.
> +
>  menu "ARMv8.1 architectural features"
>  
>  config ARM64_HW_AFDBM
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

  reply	other threads:[~2016-09-02 15:47 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-02 15:02 [PATCH v2 0/7] arm64: Privileged Access Never using TTBR0_EL1 switching Catalin Marinas
2016-09-02 15:02 ` [kernel-hardening] " Catalin Marinas
2016-09-02 15:02 ` [PATCH v2 1/7] arm64: Factor out PAN enabling/disabling into separate uaccess_* macros Catalin Marinas
2016-09-02 15:02   ` [kernel-hardening] " Catalin Marinas
2016-09-05 15:38   ` Mark Rutland
2016-09-05 15:38     ` [kernel-hardening] " Mark Rutland
2016-09-12 14:52     ` Catalin Marinas
2016-09-12 14:52       ` [kernel-hardening] " Catalin Marinas
2016-09-12 15:09       ` Mark Rutland
2016-09-12 15:09         ` [kernel-hardening] " Mark Rutland
2016-09-12 16:26         ` Catalin Marinas
2016-09-12 16:26           ` [kernel-hardening] " Catalin Marinas
2016-09-02 15:02 ` [PATCH v2 2/7] arm64: Factor out TTBR0_EL1 post-update workaround into a specific asm macro Catalin Marinas
2016-09-02 15:02   ` [kernel-hardening] " Catalin Marinas
2016-09-05 16:11   ` Mark Rutland
2016-09-05 16:11     ` [kernel-hardening] " Mark Rutland
2016-09-02 15:02 ` [PATCH v2 3/7] arm64: Introduce uaccess_{disable, enable} functionality based on TTBR0_EL1 Catalin Marinas
2016-09-02 15:02   ` [kernel-hardening] [PATCH v2 3/7] arm64: Introduce uaccess_{disable,enable} " Catalin Marinas
2016-09-05 17:20   ` [PATCH v2 3/7] arm64: Introduce uaccess_{disable, enable} " Mark Rutland
2016-09-05 17:20     ` [kernel-hardening] " Mark Rutland
2016-09-06 10:27     ` Catalin Marinas
2016-09-06 10:27       ` [kernel-hardening] " Catalin Marinas
2016-09-06 10:45       ` Mark Rutland
2016-09-06 10:45         ` [kernel-hardening] " Mark Rutland
2016-09-11 13:55         ` Ard Biesheuvel
2016-09-11 13:55           ` Ard Biesheuvel
2016-09-12  9:32           ` Catalin Marinas
2016-09-12  9:32             ` Catalin Marinas
2016-09-09 17:15   ` Catalin Marinas
2016-09-09 17:15     ` [kernel-hardening] " Catalin Marinas
2016-09-02 15:02 ` [PATCH v2 4/7] arm64: Disable TTBR0_EL1 during normal kernel execution Catalin Marinas
2016-09-02 15:02   ` [kernel-hardening] " Catalin Marinas
2016-09-06 17:31   ` Mark Rutland
2016-09-06 17:31     ` [kernel-hardening] " Mark Rutland
2016-09-02 15:02 ` [PATCH v2 5/7] arm64: Handle faults caused by inadvertent user access with PAN enabled Catalin Marinas
2016-09-02 15:02   ` [kernel-hardening] " Catalin Marinas
2016-09-02 15:02 ` [PATCH v2 6/7] arm64: xen: Enable user access before a privcmd hvc call Catalin Marinas
2016-09-02 15:02   ` [kernel-hardening] " Catalin Marinas
2016-09-02 15:02 ` [PATCH v2 7/7] arm64: Enable CONFIG_ARM64_TTBR0_PAN Catalin Marinas
2016-09-02 15:02   ` [kernel-hardening] " Catalin Marinas
2016-09-02 15:47   ` Mark Rutland [this message]
2016-09-02 15:47     ` [kernel-hardening] " Mark Rutland
2016-09-07 23:20 ` [PATCH v2 0/7] arm64: Privileged Access Never using TTBR0_EL1 switching Kees Cook
2016-09-07 23:20   ` [kernel-hardening] " Kees Cook
2016-09-08 12:51   ` Catalin Marinas
2016-09-08 12:51     ` [kernel-hardening] " Catalin Marinas
2016-09-08 15:50     ` Kees Cook
2016-09-08 15:50       ` [kernel-hardening] " Kees Cook
2016-09-09 16:31     ` Mark Rutland
2016-09-09 16:31       ` [kernel-hardening] " Mark Rutland
2016-09-09 18:24       ` Kees Cook
2016-09-09 18:24         ` [kernel-hardening] " Kees Cook
2016-09-09 23:40 ` [kernel-hardening] " David Brown
2016-09-09 23:40   ` David Brown
2016-09-10  9:51 ` Catalin Marinas
2016-09-10  9:51   ` [kernel-hardening] " Catalin Marinas
2016-09-10 10:56   ` Ard Biesheuvel
2016-09-10 10:56     ` [kernel-hardening] " Ard Biesheuvel
2016-09-11 12:16     ` Catalin Marinas
2016-09-11 12:16       ` [kernel-hardening] " Catalin Marinas

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