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    SubjectRe: [PATCH v2 0/3] Replay Protected Memory Block (RPMB) subsystem
    Hi Sumit,

    On Fri, Feb 2, 2024 at 10:59 AM Sumit Garg <sumit.garg@linaro.org> wrote:
    >
    > Hi Jens,
    >
    > On Wed, 31 Jan 2024 at 23:14, Jens Wiklander <jens.wiklander@linaro.org> wrote:
    > >
    > > Hi,
    > >
    > > It's been a while since Shyam posted the last version [1] of this patch
    > > set. I've pinged Shyam, but so far I've had no reply so I'm trying to make
    > > another attempt with the RPMB subsystem. If Shyam has other changes in mind
    > > than what I'm adding here I hope we'll find a way to cover that too. I'm
    > > calling it version two of the patchset since I'm trying to address all
    > > feedback on the previous version even if I'm starting a new thread.
    > >
    > > This patch set introduces a new RPMB subsystem, based on patches from [1],
    > > [2], and [3]. The RPMB subsystem aims at providing access to RPMB
    > > partitions to other kernel drivers, in particular the OP-TEE driver. A new
    > > user space ABI isn't needed, we can instead continue using the already
    > > present ABI when writing the RPMB key during production.
    > >
    > > I've added and removed things to keep only what is needed by the OP-TEE
    > > driver. Since the posting of [3], there has been major changes in the MMC
    > > subsystem so "mmc: block: register RPMB partition with the RPMB subsystem"
    > > is in practice completely rewritten.
    > >
    > > With this OP-TEE can access RPMB during early boot instead of having to
    > > wait for user space to become available as in the current design [4].
    > > This will benefit the efi variables [5] since we wont rely on userspace as
    > > well as some TPM issues [6] that were solved.
    > >
    > > The OP-TEE driver finds the correct RPMB device to interact with by
    > > iterating over available devices until one is found with a programmed
    > > authentication matching the one OP-TEE is using. This enables coexisting
    > > users of other RPMBs since the owner can be determined by who knows the
    > > authentication key.
    > >
    > > I've put myself as a maintainer for the RPMB subsystem as I have an
    > > interest in the OP-TEE driver to keep this in good shape. However, if you'd
    > > rather see someone else taking the maintainership that's fine too. I'll
    > > help keep the subsystem updated regardless.
    > >
    > > [1] https://lore.kernel.org/lkml/20230722014037.42647-1-shyamsaini@linux.microsoft.com/
    > > [2] https://lore.kernel.org/lkml/20220405093759.1126835-2-alex.bennee@linaro.org/
    > > [3] https://lore.kernel.org/linux-mmc/1478548394-8184-2-git-send-email-tomas.winkler@intel.com/
    > > [4] https://optee.readthedocs.io/en/latest/architecture/secure_storage.html#rpmb-secure-storage
    > > [5] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c44b6be62e8dd4ee0a308c36a70620613e6fc55f
    > > [6] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7269cba53d906cf257c139d3b3a53ad272176bca
    > >
    > > Thanks,
    > > Jens
    > >
    > > Changes since Shyam's RFC:
    > > * Removed the remaining leftover rpmb_cdev_*() function calls
    > > * Refactored the struct rpmb_ops with all the previous ops replaced, in
    > > some sense closer to [3] with the route_frames() op
    > > * Added rpmb_route_frames()
    > > * Added struct rpmb_frame, enum rpmb_op_result, and enum rpmb_type from [3]
    > > * Removed all functions not needed in the OP-TEE use case
    > > * Added "mmc: block: register RPMB partition with the RPMB subsystem", based
    > > on the commit with the same name in [3]
    > > * Added "optee: probe RPMB device using RPMB subsystem" for integration
    > > with OP-TEE
    > > * Moved the RPMB driver into drivers/misc/rpmb-core.c
    > > * Added my name to MODULE_AUTHOR() in rpmb-core.c
    > > * Added an rpmb_mutex to serialize access to the IDA
    > > * Removed the target parameter from all rpmb_*() functions since it's
    > > currently unused
    > >
    >
    > Thanks for working on this. This is a huge step towards supporting TEE
    > kernel client drivers. IIRC you mentioned offline to test it with
    > virtio RPMB on Qemu. If it works then I would be happy to try it out
    > as well.

    I'm sorry, I didn't get far enough with that. I've been testing on a
    HiKey 620 with a removable HardKernel eMMC. So I have two RPMBs to
    test with.

    >
    > Along with that can you point me to the corresponding OP-TEE OS
    > changes? I suppose as you are just adding 3 new RPC calls in patch#3,
    > so we should be fine ABI wise although people have to uprev both
    > OP-TEE and Linux kernel to get this feature enabled. However, OP-TEE
    > should gate those RPCs behind a config flag or can just fallback to
    > user-space supplicant if those aren't supported?

    Here are the OP-TEE OS patches
    https://github.com/jenswi-linaro/optee_os/tree/rpmb_probe .
    Yes, there's automatic fallback to the user-space supplicant if the
    kernel reports that the new RPCs aren't supported and the kernel will
    not use the in-kernel driver unless the new RPCs have been used.

    Cheers,
    Jens

    >
    > -Sumit
    >
    > >
    > >
    > > Jens Wiklander (3):
    > > rpmb: add Replay Protected Memory Block (RPMB) subsystem
    > > mmc: block: register RPMB partition with the RPMB subsystem
    > > optee: probe RPMB device using RPMB subsystem
    > >
    > > MAINTAINERS | 7 +
    > > drivers/misc/Kconfig | 9 ++
    > > drivers/misc/Makefile | 1 +
    > > drivers/misc/rpmb-core.c | 247 ++++++++++++++++++++++++++++++
    > > drivers/mmc/core/block.c | 177 +++++++++++++++++++++
    > > drivers/tee/optee/core.c | 1 +
    > > drivers/tee/optee/ffa_abi.c | 2 +
    > > drivers/tee/optee/optee_private.h | 6 +
    > > drivers/tee/optee/optee_rpc_cmd.h | 33 ++++
    > > drivers/tee/optee/rpc.c | 221 ++++++++++++++++++++++++++
    > > drivers/tee/optee/smc_abi.c | 2 +
    > > include/linux/rpmb.h | 184 ++++++++++++++++++++++
    > > 12 files changed, 890 insertions(+)
    > > create mode 100644 drivers/misc/rpmb-core.c
    > > create mode 100644 include/linux/rpmb.h
    > >
    > >
    > > base-commit: 41bccc98fb7931d63d03f326a746ac4d429c1dd3
    > > --
    > > 2.34.1
    > >

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