Messages in this thread | | | From | Masahisa Kojima <> | Date | Fri, 27 Oct 2023 16:26:50 +0900 | Subject | Re: [PATCH v9 0/6] introduce tee-based EFI Runtime Variable Service |
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Hi Ilias,
On Wed, 18 Oct 2023 at 20:35, Ilias Apalodimas <ilias.apalodimas@linaro.org> wrote: > > 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.
"# efi-updatevar -f noPK.auth PK" does not reach the kernel efivarfs code. With strace, error occurs when efi-updatevar tries to open /sys/firmware/efi/efivars/KEK-*** file. I guess O_TRUNC option in open() is not required?
openat(AT_FDCWD, "/sys/firmware/efi/efivars/KEK-8be4df61-93ca-11d2-aa0d-00e098032b8c", O_RDWR|O_CREAT|O_TRUNC, 0644) = -1 EPERM (Operation not permitted) write(2, "Failed to update KEK: ", 22Failed to update KEK: ) = 22 write(2, "Operation not permitted\n", 24Operation not permitted ) = 24 exit_group(1) = ? +++ exited with 1 +++
We can use "efivar" instead to remove the keys. It also works for KEK and db. # efi-updatevar -f PK.auth PK # efi-updatevar -f noPK.auth PK <--- it does not work # efivar -w -n 8be4df61-93ca-11d2-aa0d-00e098032b8c-PK -f noPK.auth <--- it works
> > 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
I could not reproduce this issue. I tried the following command then reboot the board. Linux boots fine. # efi-updatevar -f KEK.auth KEK # efi-updatevar -f db.auth db
I also enroll the PK, then UEFI secure boot works. Signed grub and signed kernel boot in UEFI secure boot enabled.
Are there any additional steps to reproduce?
Thanks, Masahisa Kojima
> > 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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