RE: [PATCH v2 0/4] rpmb subsystem, uapi and virtio-rpmb driver

Zhu, Bing
2023-06-01T01:03:53Z

As an alternative, Is it possible to change ftpm design not to depend on RPMB access at the earlier/boot stage? Because to my understanding, typically PCRs don't require persistent/NV storage (for example, before RPMB or tee-supplicant is ready, use TEE memory instead as temporary storage)

Bing

IPAS Security Brown Belt (https://www.credly.com/badges/69ea809f-3a96-4bc7-bb2f-442c1b17af26)
System Software Engineering
Software and Advanced Technology Group
Zizhu Science Park, Shanghai, China

-----Original Message-----
From: Shyam Saini <shyamsaini@linux.microsoft.com>
Sent: Thursday, June 1, 2023 3:10 AM
To: alex.bennee@linaro.org
Cc: code@tyhicks.com; Matti.Moell@opensynergy.com; arnd@linaro.org; Zhu, Bing <bing.zhu@intel.com>; hmo@opensynergy.com; ilias.apalodimas@linaro.org; joakim.bech@linaro.org; linux-kernel@vger.kernel.org; linux-mmc@vger.kernel.org; linux-scsi@vger.kernel.org; maxim.uvarov@linaro.org; ruchika.gupta@linaro.org; Winkler, Tomas <tomas.winkler@intel.com>; ulf.hansson@linaro.org; Huang, Yang <yang.huang@intel.com>; sumit.garg@linaro.org; jens.wiklander@linaro.org; op-tee@lists.trustedfirmware.org
Subject: [PATCH v2 0/4] rpmb subsystem, uapi and virtio-rpmb driver

Hi Alex,

[ Resending, Sorry for the noise ]

Are you still working on it or planning to resubmit it ?

[1] The current optee tee kernel driver implementation doesn't work when IMA is used with optee implemented ftpm.

The ftpm has dependency on tee-supplicant which comes once the user space is up and running and IMA attestation happens at boot time and it requires to extend ftpm PCRs.

But IMA can't use PCRs if ftpm use secure emmc RPMB partition. As optee can only access RPMB via tee-supplicant(user space). So, there should be a fast path to allow optee os to access the RPMB parititon without waiting for user-space tee supplicant.

To achieve this fast path linux optee driver and mmc driver needs some work and finally it will need RPMB driver which you posted.

Please let me know what's your plan on this.

[1] https://optee.readthedocs.io/en/latest/architecture/secure_storage.html

Best Regards,
Shyam