Re: [PATCH v5 2/2] misc: open-dice: Add driver to expose DICE data to userspace

[Rob Herring <robh@kernel.org>]

On Tue, Dec 21, 2021 at 05:45:02PM +0000, David Brazdil wrote:
> Open Profile for DICE is an open protocol for measured boot compatible
> with the Trusted Computing Group's Device Identifier Composition
> Engine (DICE) specification. The generated Compound Device Identifier
> (CDI) certificates represent the hardware/software combination measured
> by DICE, and can be used for remote attestation and sealing.
> 
> Add a driver that exposes reserved memory regions populated by firmware
> with DICE CDIs and exposes them to userspace via a character device.
> 
> Userspace obtains the memory region's size from read() and calls mmap()
> to create a mapping of the memory region in its address space. The
> mapping is not allowed to be write+shared, giving userspace a guarantee
> that the data were not overwritten by another process.
> 
> Userspace can also call write(), which triggers a wipe of the DICE data
> by the driver. Because both the kernel and userspace mappings use
> write-combine semantics, all clients observe the memory as zeroed after
> the syscall has returned.
> 
> Cc: Andrew Scull <ascull@google.com>
> Cc: Will Deacon <will@kernel.org>
> Signed-off-by: David Brazdil <dbrazdil@google.com>
> ---
>  drivers/misc/Kconfig     |  12 +++
>  drivers/misc/Makefile    |   1 +
>  drivers/misc/open-dice.c | 188 +++++++++++++++++++++++++++++++++++++++
>  drivers/of/platform.c    |   1 +

Acked-by: Rob Herring <robh@kernel.org>

>  4 files changed, 202 insertions(+)
>  create mode 100644 drivers/misc/open-dice.c