On Thu, 1 Jun 2023 at 11:02, Ilias Apalodimas ilias.apalodimas@linaro.org wrote:
Hi Bing
On Thu, 1 Jun 2023 at 04:03, Zhu, Bing bing.zhu@intel.com wrote:
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)
I am not entirely sure this will solve our problem here. You are right that we shouldn't depend on the supplicant to extend PCRs. But what happens if an object is sealed against certain PCR values? We are back to the same problem
+1
Temporary storage may be a stop gap solution for some use-cases but having a fast path access to RPMB via kernel should be our final goal. I would suggest we start small with the MMC subsystem to expose RPMB access APIs for OP-TEE driver rather than a complete RPMB subsystem.
-Sumit
Thanks /Ilias
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