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 > > [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 ? -- Jerome
