Messages in this thread | | | Date | Tue, 22 Aug 2023 11:47:54 -0700 (PDT) | From | Shyam Saini <> | Subject | Re: [RFC, PATCH 1/1] rpmb: add Replay Protected Memory Block (RPMB) driver |
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Hi Jerome,
> > > On 8/17/23 01:31, Shyam Saini wrote: >> >> Hi Ulf, >> >>> On Sat, 22 Jul 2023 at 03:41, Shyam Saini >>> <shyamsaini@linux.microsoft.com> wrote: >>>> >>>> From: Alex Bennée <alex.bennee@linaro.org> >>>> >>>> [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).
Thanks, but we may still need to address with multiple RPMB targets/regions in case of UFS/NVMe.
>> 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 ?
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