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References: <20240227153132.2611499-1-jens.wiklander@linaro.org> <20240227153132.2611499-2-jens.wiklander@linaro.org>
In-Reply-To: <20240227153132.2611499-2-jens.wiklander@linaro.org>
From: Linus Walleij <linus.walleij@linaro.org>
Date: Tue, 5 Mar 2024 13:24:02 +0100
Message-ID: <CACRpkdZBWBio8kvKuVzj2CknCb4eS=VB2EqUsAK-vf4e328icg@mail.gmail.com>
Subject: Re: [PATCH v3 1/3] rpmb: add Replay Protected Memory Block (RPMB) subsystem
To: Jens Wiklander <jens.wiklander@linaro.org>
Cc: linux-kernel@vger.kernel.org, linux-mmc@vger.kernel.org, 
	op-tee@lists.trustedfirmware.org, 
	Shyam Saini <shyamsaini@linux.microsoft.com>, Ulf Hansson <ulf.hansson@linaro.org>, 
	Jerome Forissier <jerome.forissier@linaro.org>, Sumit Garg <sumit.garg@linaro.org>, 
	Ilias Apalodimas <ilias.apalodimas@linaro.org>, Bart Van Assche <bvanassche@acm.org>, 
	Randy Dunlap <rdunlap@infradead.org>, Ard Biesheuvel <ardb@kernel.org>, Arnd Bergmann <arnd@arndb.de>, 
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Tomas Winkler <tomas.winkler@intel.com>, 
	=?UTF-8?B?QWxleCBCZW5uw6ll?= <alex.bennee@linaro.org>
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Hi Jens,

thanks for your patch!

On Tue, Feb 27, 2024 at 4:31=E2=80=AFPM Jens Wiklander
<jens.wiklander@linaro.org> wrote:

> A number of storage technologies support a specialised hardware
> partition designed to be resistant to replay attacks. The underlying
> HW protocols differ but the operations are common. The RPMB partition
> cannot be accessed via standard block layer, but by a set of specific
> RPMB commands: WRITE, READ, GET_WRITE_COUNTER, and PROGRAM_KEY. Such a
> partition provides authenticated and replay protected access, hence
> suitable as a secure storage.
>
> The initial aim of this patch is to provide a simple RPMB driver
> interface which can be accessed by the optee driver to facilitate early
> RPMB access to OP-TEE OS (secure OS) during the boot time.
>
> A TEE device driver can claim the RPMB interface, for example, via
> rpmb_interface_register() or rpmb_dev_find_device(). The RPMB driver
> provides a callback to route RPMB frames to the RPMB device accessible
> via rpmb_route_frames().
>
> The detailed operation of implementing the access is left to the TEE
> device driver itself.
>
> Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
> Signed-off-by: Alex Benn=C3=A9e <alex.bennee@linaro.org>
> Signed-off-by: Shyam Saini <shyamsaini@linux.microsoft.com>
> Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

I would mention in the commit that the subsystem is currently
only used with eMMC but is designed to be used also by UFS
and NVME. Nevertheless, no big deal so:
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

> +config RPMB
> +       tristate "RPMB partition interface"
> +       depends on MMC

depends on MMC || SCSI_UFSHCD || NVME_CORE
?

Or do we want to hold it off until we implement the backends?

Yours,
Linus Walleij