Messages in this thread | | | Date | Wed, 18 Oct 2023 14:35:09 +0300 | From | Ilias Apalodimas <> | Subject | Re: [PATCH v9 0/6] introduce tee-based EFI Runtime Variable Service |
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Kojima-san,
I found some time to do some extended testing here's what I found
Switching the permissions from RO->RW when the supplicant is started works correctly # mount | grep efiv efivarfs on /sys/firmware/efi/efivars type efivarfs (ro,nosuid,nodev,noexec,relatime) # tee-supplicant -d [ 77.374878] efivars: Unregistered efivars operations [ 77.381604] Use tee-based EFI runtime variable services [ 77.386862] efivars: Registered efivars operations # mount | grep efiv efivarfs on /sys/firmware/efi/efivars type efivarfs (rw,nosuid,nodev,noexec,relatime) I didn't test unbinding yet, but I assume it's going to work fine and remove the efivar ops.
Reading an writing non-authenticated EFI variables seems to work fine. I verified this with U-Boot and the BootOrder changed correctly. # efibootmgr -o 0001,0002,0000 BootCurrent: 0002 BootOrder: 0001,0002,0000 Boot0000* nvme 0:1 Boot0001* nvme 0:2 Boot0002* debian # efibootmgr -o 0002,0000,0001 BootCurrent: 0002 BootOrder: 0002,0000,0001 Boot0000* nvme 0:1 Boot0001* nvme 0:2 Boot0002* debian
Writing authenticated EFI variables works the first time. I also dumped those variables from both Linux and U-Boot and they matched # efi-updatevar -f PK.auth PK # efi-updatevar -f KEK.auth KEK # efi-updatevar -f db.auth db
But removing the PK at runtime fails. # efi-updatevar -f noPK.auth PK # Failed to update PK: Operation not permitted My guess is that the EDK2 code prohibits that, but we need to check why this is happening. I also got similar failures trying to update KEK and db.
But the most worrying thing is this. From Linux program KEK and db # efi-updatevar -f KEK.auth KEK # efi-updatevar -f db.auth db
Reboot the machine and U-Boot complains when it tries to populate the runtime vars with: Loading Linux 6.6.0-rc2-00654-g82a013b37495 ... Loading initial ramdisk ... EFI stub: Booting Linux Kernel... EFI stub: Using DTB from configuration table EFI stub: Exiting boot services... Can't populate EFI variables. No runtime variables will be available <-- This
If you rewrite those vars from the U-Boot shell everything seems to come back to normal => tftp $loadaddr 192.168.49.5:noKEK.auth && setenv -e -nv -bs -rt -at -i $loadaddr:$filesize KEK => tftp $loadaddr 192.168.49.5:nodb.auth && setenv -e -nv -bs -rt -at -i $loadaddr:$filesize db => tftp $loadaddr 192.168.49.5:KEK.auth && setenv -e -nv -bs -rt -at -i $loadaddr:$filesize KEK => tftp $loadaddr 192.168.49.5:db.auth && setenv -e -nv -bs -rt -at -i $loadaddr:$filesize db
Loading Linux 6.6.0-rc2-00654-g82a013b37495 ... Loading initial ramdisk ... EFI stub: Booting Linux Kernel... EFI stub: Using DTB from configuration table EFI stub: Exiting boot services...
Let me know if you need any more information
Regards /Ilias On Fri, Oct 13, 2023 at 04:45:33PM +0900, Masahisa Kojima 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. > > Changelog: > 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@linaro.org/ > > 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@linaro.org/ > > 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 (5): > 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 > tee: optee: restore efivars ops when tee-supplicant stops > > 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 | 617 +++++++++++++++++++ > drivers/firmware/efi/vars.c | 8 + > drivers/tee/optee/supp.c | 4 + > fs/efivarfs/super.c | 45 ++ > include/linux/efi.h | 13 + > 9 files changed, 957 insertions(+) > create mode 100644 drivers/firmware/efi/stmm/mm_communication.h > create mode 100644 drivers/firmware/efi/stmm/tee_stmm_efi.c > > > base-commit: b691118f2c44d16b84fc65b8147b33620eb18cac > -- > 2.30.2 >
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