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.microso... [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.win... [4] https://optee.readthedocs.io/en/latest/architecture/secure_storage.html#rpmb... [5] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... [6] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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