On Wed, 23 Aug 2023 at 00:29, Shyam Saini <shyamsaini@xxxxxxxxxxxxxxxxxxx> wrote: > > > Hi Sumit, > > > On Mon, 21 Aug 2023 at 15:19, Jerome Forissier > > <jerome.forissier@xxxxxxxxxx> wrote: > >> > >> > >> > >> On 8/17/23 01:31, Shyam Saini wrote: > >>> > >>> Hi Ulf, > >>> > >>>> On Sat, 22 Jul 2023 at 03:41, Shyam Saini > >>>> <shyamsaini@xxxxxxxxxxxxxxxxxxx> wrote: > >>>>> > >>>>> From: Alex Bennée <alex.bennee@xxxxxxxxxx> > >>>>> > >>>>> [This is patch 1 from [1] Alex's submission and this RPMB layer was > >>>>> originally proposed by [2]Thomas Winkler ] > >>>>> > >>>>> 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 > >>>>> 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 which > >>>>> can be accessed by Linux's optee driver to facilitate fast-path for > >>>>> RPMB access to optee OS(secure OS) during the boot time. [1] Currently, > >>>>> Optee OS relies on user-tee supplicant to access eMMC RPMB partition. > >>>>> > >>>>> A TEE device driver can claim the RPMB interface, for example, via > >>>>> class_interface_register(). The RPMB driver provides a series of > >>>>> operations for interacting with the device. > >>>> > >>>> I don't quite follow this. More exactly, how will the TEE driver know > >>>> what RPMB device it should use? > >>> > >>> I don't have complete code to for this yet, but i think OP-TEE driver > >>> should register with RPMB subsystem and then we can have eMMC/UFS/NVMe > >>> specific implementation for RPMB operations. > >>> > >>> Linux optee driver can handle RPMB frames and pass it to RPMB subsystem > >>> > > > > It would be better to have this OP-TEE use case fully implemented. So > > that we can justify it as a valid user for this proposed RPMB > > subsystem. If you are looking for any further suggestions then please > > let us know. > > I was looking into UFS/NVMe user-space utils, it seems we may have to > adapt rpmb frame data structure in optee-os to to handle NVMe/UFS > specific bits. > > For nvme rpmb data frame, I think we would need an extra "target" member > in rpmb data frame structure, > as NVMe can support upto 7 RPMB units, see [1] "struct rpmb_data_frame_t" > UFS may support upto 3 or 4 RPMB regions. > > So even if we use CID to uniquely identify RPMB device either from > eMMC/NVMe/UFS, we still need identify which RPMB target/unit in case > if the device is NVMe, and which RPMB region if the device UFS. > > Also both NVMe/UFS utils have two extra RPMB operations implemented, > Although new request/response operation than eMMC spec: > 1) Authenticated Device Configuration Block Write > 2) Authenticated Device Configuration Block Read > > see [2] enum rpmb_request/response_type and [3]enum rpmb_op_type > > do we need those implemented as well ? IMO, we should start with eMMC RPMB support first with OP-TEE. This is what OP-TEE currently supports. And later on we can extend that framework for UFS and NVMe RPMB. We need to put extra care here regarding the eMMC RPMB ABI among OP-TEE and Linux kernel. It should be designed in a way that it is future compatible for UFS/NMVe. IOW, the bits that you have already discovered above. Also, we have to be backwards compatible with eMMC RPMB ABI towards u-boot too since OP-TEE would use the same ABI whether it is towards Linux or u-boot. -Sumit > > Please let me know what you think about these. > > [1] https://github.com/linux-nvme/nvme-cli/blob/master/nvme-rpmb.c#L252 > [2] https://github.com/linux-nvme/nvme-cli/blob/master/nvme-rpmb.c#L230 > [3] https://github.com/westerndigitalcorporation/ufs-utils/blob/dev/ufs_rpmb.c#L27 > > >>> [1] U-Boot has mmc specific implementation > >>> > >>> I think OPTEE-OS has CFG_RPMB_FS_DEV_ID option > >>> CFG_RPMB_FS_DEV_ID=1 for /dev/mmcblk1rpmb, > >> > >> Correct. Note that tee-supplicant will ignore this device ID if --rmb-cid > >> is given and use the specified RPMB instead (the CID is a non-ambiguous way > >> to identify a RPMB device). > >> > >>> but in case if a > >>> system has multiple RPMB devices such as UFS/eMMC/NVMe, one them > >>> should be declared as secure storage and optee should access that one only. > >> > >> Indeed, that would be an equivalent of tee-supplicant's --rpmb-cid. > >> > >>> Sumit, do you have suggestions for this ? > >> > > > > I would suggest having an OP-TEE secure DT property that would provide > > the RPMB CID which is allocated to the secure world. > > > > -Sumit > > > >> > >> -- > >> Jerome > >
