On Thu, 1 Jun 2023 at 08:49, Sumit Garg <sumit.garg@xxxxxxxxxx> wrote: > > On Thu, 1 Jun 2023 at 11:02, Ilias Apalodimas > <ilias.apalodimas@xxxxxxxxxx> wrote: > > > > Hi Bing > > > > On Thu, 1 Jun 2023 at 04:03, Zhu, Bing <bing.zhu@xxxxxxxxx> 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. I discussed with the OP-TEE maintainers about adding parts of the supplicant in the kernel. The supplicant 'just' sends an ioctl to store/read stuff anyway. So it would make sense to have a closer and see if that looks reasonable. Thanks /Ilias > > -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@xxxxxxxxxxxxxxxxxxx> > > > Sent: Thursday, June 1, 2023 3:10 AM > > > To: alex.bennee@xxxxxxxxxx > > > Cc: code@xxxxxxxxxxx; Matti.Moell@xxxxxxxxxxxxxxx; arnd@xxxxxxxxxx; Zhu, Bing <bing.zhu@xxxxxxxxx>; hmo@xxxxxxxxxxxxxxx; ilias.apalodimas@xxxxxxxxxx; joakim.bech@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-mmc@xxxxxxxxxxxxxxx; linux-scsi@xxxxxxxxxxxxxxx; maxim.uvarov@xxxxxxxxxx; ruchika.gupta@xxxxxxxxxx; Winkler, Tomas <tomas.winkler@xxxxxxxxx>; ulf.hansson@xxxxxxxxxx; Huang, Yang <yang.huang@xxxxxxxxx>; sumit.garg@xxxxxxxxxx; jens.wiklander@xxxxxxxxxx; op-tee@xxxxxxxxxxxxxxxxxxxxxxxxx > > > 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
