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.
Acked-by: Rob Herring <robh@kernel.org>
Cc: Andrew Scull <ascull@google.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: David Brazdil <dbrazdil@google.com>
Link: https://lore.kernel.org/r/20220126231237.529308-3-dbrazdil@google.com
[dbrazdil@: Fixed context conflicts in reserved_mem_matches[] and Makefile]
Bug: 198197082
Change-Id: Iabd65f4d20036bb452e4103c7722f220c2273c81
(cherry picked from commit 8941930d125c97e7d22fb24eb10b431fad4436f4)
784db42db8