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

Jens Wiklander
2023-06-12T17:07:08Z

Hi Alex,

On Fri, Jun 2, 2023 at 10:26 AM Ilias Apalodimas
<ilias.apalodimas@linaro.org> wrote:
>
> On Thu, 1 Jun 2023 at 08:49, Sumit Garg <sumit.garg@linaro.org> wrote:
> >
> > 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.
>
> 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

I was trying to create a setup to test this. I've added the kernel
patches on top of https://github.com/linaro-swg/linux/tree/optee. The
QEMU branch is a bit dated and I had to add
3a845a214b42 target/arm: allow setting SCR_EL3.EnTP2 when FEAT_SME is
implemented
d4a7b0ef1a03 hw/arm/boot: set CPTR_EL3.ESM and SCR_EL3.EnTP2 when
booting Linux with EL3
9745a003f878 hw/intc/arm_gicv3: fix prio masking on pmr write
beeec926d24a target/arm: mark SP_EL1 with ARM_CP_EL3_NO_EL2_KEEP
on top of that branch to be able to boot to the Linux kernel.

I have the vhost-user-rpmb process running and connected with QEMU,
but around (guessing really) when the RPMB subsystem is initializing
the process dies with:
================ Vhost user message ================
Request: VHOST_USER_SET_VRING_ADDR (9)
Flags: 0x1
Size: 40
vhost-user-rpmb-INFO: 18:58:08.312: vrpmb_process_msg: msg
VHOST_USER_SET_VRING_ADDR(9)
vhost_vring_addr:
index: 0
flags: 0
desc_user_addr: 0x00007ff15fa91000
used_user_addr: 0x00007ff15fa91080
avail_user_addr: 0x00007ff15fa91040
log_guest_addr: 0x0000000041c91080
Setting virtq addresses:
vring_desc at (nil)
vring_used at (nil)
vring_avail at (nil)

(vhost-user-rpmb:3236474): vhost-user-rpmb-CRITICAL **: 18:58:08.312:
Invalid vring_addr message

Among other options, I'm starting QEMU with -machine
virt,secure=on,mte=off,gic-version=3,virtualization=false to enable
the secure world.

Do you have an idea of what might be wrong? Where should I start looking?

Thanks,
Jens

>
> /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@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