Re: [PATCH v10 0/5] introduce tee-based EFI Runtime Variable Service

[Masahisa Kojima]

Hi Ilias,

On Tue, 7 Nov 2023 at 20:02, Ilias Apalodimas
<ilias.apalodimas@xxxxxxxxxx> wrote:
>
> Kojima-san
>
> patch #5 wasn't applying correctly. I guess this is based on efi-next?

Yes, my series is based on efi-next.

>
> On Tue, 7 Nov 2023 at 07:41, Masahisa Kojima <masahisa.kojima@xxxxxxxxxx> wrote:
> >
> > This series introduces the tee-based EFI Runtime Variable Service.
> >
> > The eMMC device is typically owned by the non-secure world(linux in
> > this case). There is an existing solution utilizing eMMC RPMB partition
> > for EFI Variables, it is implemented by interacting with
> > OP-TEE, StandaloneMM(as EFI Variable Service Pseudo TA), eMMC driver
> > and tee-supplicant. The last piece is the tee-based variable access
> > driver to interact with OP-TEE and StandaloneMM.
> >
> > This driver depends on the tee-supplicant. When the tee-supplicant
> > stops, this driver needs to be unbound from user-space script or tool,
> > relevant patch is posted[1].
> >
> > [1] https://lore.kernel.org/all/20231102073056.174480-2-sumit.garg@xxxxxxxxxx/
>
> I managed to test with Sumit's patch on top. Unbinding the device
> works nicely and mounts the efivarfs as RO.
>
> Reading and writing authenticated and non authenticated variables
> works as well.  The only 'problem' I found was this sequence
>
> efi-updatevar -f PK.auth PK
> efivar -w -n 8be4df61-93ca-11d2-aa0d-00e098032b8c-PK -f noPK.auth
> efivar -w -n 8be4df61-93ca-11d2-aa0d-00e098032b8c-PK -f noPK.auth
> efi-updatevar -f PK.auth PK
>
> For some reason this leaves an empty 'PK' in the database.  But that
> PK only appears in Linux not in the firmware and if you reboot, it's
> gone.  I am pretty sure this isn't related to this patchset
>
> Doing
> efi-updatevar -f PK.auth PK
> efivar -w -n 8be4df61-93ca-11d2-aa0d-00e098032b8c-PK -f noPK.auth
> efi-updatevar -f PK.auth PK
>
> works fine.
>
> For the series
> Tested-by: Ilias Apalodimas <ilias.apalodimas@xxxxxxxxxx>

Thank you for testing.

Regards,
Masahisa Kojima

>
>
> >
> > Changelog:
> > v9 -> v10
> > - patch #6 "tee: optee: restore efivars ops when tee-supplicant stops"
> >   is removed
> >
> > v8 -> v9
> > - patch #6 "tee: optee: restore efivars ops when tee-supplicant stops"
> >   is newly added
> > - remove !EFI_VARS_PSTORE Kconfig dependency, we have added a non-blocking
> >   set_variable and it just returns EFI_UNSUPPORTED.
> > - remove obvious comments
> >
> > v7 -> v8
> > Only patch #3 "efi: Add tee-based EFI variable driver" is updated.
> > - fix typos
> > - refactor error handling, direct return if applicable
> > - use devm_add_action_or_reset() for closing of tee context/session
> > - remove obvious comment
> >
> > v6 -> v7
> > Patch #1-#4 are not updated.
> > Patch #5 is added into this series, original patch is here:
> > https://lore.kernel.org/all/20230609094532.562934-1-ilias.apalodimas@xxxxxxxxxx/
> >
> > There are two issues in the v6 series and v7 series addresses those.
> >
> > 1) efivar ops is not restored when the tee-supplicant daemon terminates.
> >  -> As the following patch says, user must remove the device before
> >     terminating tee-supplicant daemon.
> >     https://lore.kernel.org/all/20230728134832.326467-1-sumit.garg@xxxxxxxxxx/
> >
> > 2) cause panic when someone remounts the efivarfs as RW even if
> > SetVariable is not supported
> >  -> The fifth patch addresses this issue.
> >    "[PATCH v7 5/5] efivarfs: force RO when remounting if SetVariable is
> >     not supported"
> >
> > v5 -> v6
> > - new patch #4 is added in this series, #1-#3 patches are unchanged.
> >   automatically update super block flag when the efivarops support
> >   SetVariable runtime service, so that user does not need to manually
> >   remount the efivarfs as RW.
> >
> > v4 -> v5
> > - rebase to efi-next based on v6.4-rc1
> > - set generic_ops.query_variable_info, it works as expected as follows.
> > $ df -h /sys/firmware/efi/efivars/
> > Filesystem      Size  Used Avail Use% Mounted on
> > efivarfs         16K  1.3K   15K   8% /sys/firmware/efi/efivars
> >
> > v3 -> v4:
> > - replace the reference from EDK2 to PI Specification
> > - remove EDK2 source code reference comments
> > - prepare nonblocking variant of set_variable, it just returns
> >   EFI_UNSUPPORTED
> > - remove redundant buffer size check
> > - argument name change in mm_communicate
> > - function interface changes in setup_mm_hdr to remove (void **) cast
> >
> > v2 -> v3:
> > - add CONFIG_EFI dependency to TEE_STMM_EFI
> > - add missing return code check for tee_client_invoke_func()
> > - directly call efivars_register/unregister from tee_stmm_efi.c
> >
> > rfc v1 -> v2:
> > - split patch into three patches, one for drivers/tee,
> >   one for include/linux/efi.h, and one for the driver/firmware/efi/stmm
> > - context/session management into probe() and remove() same as other tee
> > client driver
> > - StMM variable driver is moved from driver/tee/optee to driver/firmware/efi
> > - use "tee" prefix instead of "optee" in driver/firmware/efi/stmm/tee_stmm_efi.c,
> >   this file does not contain op-tee specific code, abstracted by tee layer and
> >   StMM variable driver will work on other tee implementation.
> > - PTA_STMM_CMD_COMMUNICATE -> PTA_STMM_CMD_COMMUNICATE
> > - implement query_variable_store() but currently not used
> > - no use of TEEC_SUCCESS, it is defined in driver/tee/optee/optee_private.h.
> >   Other tee client drivers use 0 instead of using TEEC_SUCCESS
> > - remove TEEC_ERROR_EXCESS_DATA status, it is referred just to output
> > error message
> >
> > Ilias Apalodimas (1):
> >   efivarfs: force RO when remounting if SetVariable is not supported
> >
> > Masahisa Kojima (4):
> >   efi: expose efivar generic ops register function
> >   efi: Add EFI_ACCESS_DENIED status code
> >   efi: Add tee-based EFI variable driver
> >   efivarfs: automatically update super block flag
> >
> >  drivers/firmware/efi/Kconfig                 |  15 +
> >  drivers/firmware/efi/Makefile                |   1 +
> >  drivers/firmware/efi/efi.c                   |  18 +
> >  drivers/firmware/efi/stmm/mm_communication.h | 236 +++++++
> >  drivers/firmware/efi/stmm/tee_stmm_efi.c     | 616 +++++++++++++++++++
> >  drivers/firmware/efi/vars.c                  |   8 +
> >  fs/efivarfs/super.c                          |  45 ++
> >  include/linux/efi.h                          |  12 +
> >  8 files changed, 951 insertions(+)
> >  create mode 100644 drivers/firmware/efi/stmm/mm_communication.h
> >  create mode 100644 drivers/firmware/efi/stmm/tee_stmm_efi.c
> >
> >
> > base-commit: 5329aa5101f73c451bcd48deaf3f296685849d9c
> > --
> > 2.39.2
> >