Re: PKCS#11 TA needs userland supplicant?

Hi,

On Fri, Apr 10, 2026 at 11:27 AM Jan Kiszka <[email protected]> wrote:
>
> On 10.04.26 10:36, Jan Kiszka wrote:
> > On 10.04.26 09:59, Jan Kiszka wrote:
> >> On 10.04.26 07:45, Jan Kiszka wrote:
> >>> On 10.04.26 07:37, Jens Wiklander wrote:
> >>>> Hi,
> >>>>
> >>>> On Thu, Apr 9, 2026 at 7:41 PM Jan Kiszka via OP-TEE
> >>>> <[email protected]> wrote:
> >>>>>
> >>>>> Hi all,
> >>>>>
> >>>>> to avoid that I'm debugging further this error I get during boot with
> >>>>> CONFIG_RPMB=y in the kernel and CFG_IN_TREE_EARLY_TAS=pkcs11/fd02c9da...:
> >>>>>
> >>>>> [    0.359372] mmcblk0boot0: mmc0:0001 QEMU!! 4.00 MiB
> >>>>> [    0.361779] mmcblk0boot1: mmc0:0001 QEMU!! 4.00 MiB
> >>>>> [    0.363761] mmcblk0rpmb: mmc0:0001 QEMU!! 2.00 MiB, chardev (248:0)
> >>>>> D/TC:? 0 tee_ta_init_session_with_context:569 Re-open trusted service 7011a688-ddde-4053-a5a9-7b3c4ddf13b8
> >>>>> D/TC:? 0 legacy_rpmb_init:1143 Trying legacy RPMB init
> >>>>
> >>>> The in-kernel routing didn't initialize as expected, so OP-TEE is
> >>>> falling back to the tee-supplicant based RPMB communication.
> >>>>
> >>>>
> >>>>> E/TC:? 0 get_rpc_alloc_res:646 RPC allocation failed. Non-secure world result: ret=0xffff000c ret_origin=0x2
> >>>>> D/TC:? 0 tee_ta_invoke_command:830 Error: f0100003 of 4
> >>>>> D/TC:? 0 tee_ta_close_session:469 csess 0xc0210910 id 1
> >>>>> D/TC:? 0 tee_ta_close_session:488 Destroy session
> >>>>>
> >>>>> Is it possible at all to run the PKCS#11 TA without userland tee-
> >>>>> supplicant? I thought it only needs the supplicant for RPMB, thus should
> >>>>> be fine with the in-kernel routing (which is active), but maybe that is
> >>>>> not true.
> >>>>
> >>>> Yes, I think so. I haven't tried it myself, though. Anyway, the log
> >>>> tells that OP-TEE isn't using in-kernel routing. You can also check
> >>>> /sys/class/tee/teepriv0/rpmb_routing_model to see what the driver has
> >>>> negotiated.
> >>>>
> >>>
> >>> # cat /sys/class/tee/teepriv0/rpmb_routing_model
> >>> kernel
> >>>
> >>> And if I build optee as module and load it later, then call "pkcs1-tool
> >>> --module /usr/lib/libckteec.so.0 -I", it also waits for userspace tee here:
> >>>
> >>> ...
> >>> F/TC:? 0 trace_syscall:147 syscall #8 (syscall_check_access_rights)
> >>> F/TC:? 0 trace_syscall:147 syscall #41 (syscall_storage_obj_open)
> >>> D/TC:? 0 legacy_rpmb_init:1143 Trying legacy RPMB init
> >>> I/TC: thread_rpc_alloc 0, arg->ret ffff0000
> >>> I/TC: get_rpc_alloc_res: bt 0 size 8192
> >>>
> >>
> >> I instrumented further, and I'm getting an OPTEE_RPC_CMD_SHM_ALLOC with
> >> OPTEE_RPC_SHM_TYPE_APPL, not OPTEE_RPC_SHM_TYPE_KERNEL - this is where
> >> things are failing or blocking.
> >>
> >
> > I think I'm getting closer: We have key-writing enabled for the QEMU
> > target (key is not persisted there yet), and that seems to enforce
> > legacy init all the time:
> >
> > https://github.com/OP-TEE/optee_os/blob/15bbaa331fb6d69466c4880a1af1e8e9580c95f1/core/tee/tee_rpmb_fs.c#L1248
> >
> > If I got it right, legacy_rpmb_init requires a userspace supplicant,
> > doesn't it?
> >

Yes

>
> Things start to make sense: The QEMU image we assemble in isar-cip-core
> [1] does the first RPMB access and the key writing already via U-Boot,
> and U-Boot's supplicant does not differentiate between the two
> RPC_SHM_TYPEs - how should it? So, RPMB initialization is already done
> when the kernel later on loads its optee driver and starts to communicate.

Yes, but I was expecting tee_rpmb_reinit() to be called from the
Device PTA when the kernel has discovered the RPMB device.
tee_rpmb_reinit() causes the RPMB driver in OP-TEE to restart probing
and should switch from the legacy setup.

>
> In the setup above, though, we do not have a U-Boot, we directly boot
> from TF-A into the Linux. And that seems to send us into the error /
> blocking on tee-supplicant from userspace.

Without a key programmed into RPMB?

>
> Can / should this be changed?

It sounds like the problem could be RPMB key programming. I'm testing
in-kernel RPMB routing where the key is already programmed for each
release.

We want to move away from OP-TEE programming the RPMB key, so a more
advanced combination with that seems the wrong direction.

Cheers,
Jens