[PATCH v3 00/24] pSeries dynamic secure boot secvar interface + platform keyring loading

Andrew Donnellan
2023-01-18T06:35:21Z

This series exposes an interface to userspace for reading and writing
secure variables contained within the PowerVM LPAR Platform KeyStore
(PLPKS) for the purpose of configuring dynamic secure boot, and adds
the glue required to load keys from the PLPKS into the platform keyring.

This series builds on past work by Nayna Jain[0] in exposing PLPKS
variables to userspace. Rather than being a generic interface for
interacting with the keystore, however, we use the existing powerpc
secvar infrastructure to only expose objects in the keystore used
for dynamic secure boot. This has the benefit of leveraging an
existing interface and making the implementation relatively minimal.

This series integrates a previous series to fix some bugs in PLPKS
and implement support for signed updates[1], and a cleanup patch from
Michael Ellerman[2].

There are a few relevant details to note about the implementation:

* New additions to the secvar API: format(), max_size(), config_attrs,
var_names

* New optional sysfs directory "config/" for arbitrary ASCII variables

* Some OPAL-specific code has been relocated from secvar-sysfs.c to
powernv platform code. Would appreciate any powernv testing!

* Variable names are fixed and only those used for secure boot are
exposed. This is not a generic PLPKS interface, but also doesn't
preclude one being added in future.

With this series, both powernv and pseries platforms support dynamic
secure boot through the same interface.

[0]: https://lore.kernel.org/linuxppc-dev/20221106210744.603240-1-nayna@linux.ibm.com/
[1]: https://lore.kernel.org/linuxppc-dev/20221220071626.1426786-1-ajd@linux.ibm.com/
[2]: https://lore.kernel.org/linuxppc-dev/20230112023819.1692452-1-mpe@ellerman.id.au/

v1: https://lore.kernel.org/linuxppc-dev/20221228072943.429266-1-ruscur@russell.cc/
v2: https://lore.kernel.org/linuxppc-dev/20221230042014.154483-1-ruscur@russell.cc/

=================

Changes in v3:

Integrate Andrew's PLPKS bugfixes and enhancements series and Michael
Ellerman's u64 cleanup patch into this series (and update the other
patches to use u64)

New patches to load keys from the PLPKS into the kernel's platform
keyring (ruscur)

New patches to pass PLPKS password to new kernels when kexecing
(ruscur)

Improve handling of format strings (ruscur)

Clean up secvar error messages (ajd)

Merge config attributes into secvar_operations (mpe)

Add a new static variable names API rather than (ab)using get_next()
(ajd/mpe)

Warning message when PAGE_SIZE is smaller than the max object size
(ajd)

Move plpks.h to the include directory, and move a bunch of constants
in there with a consistent naming scheme

Refresh PLPKS config values whenever plpks_get_usedspace() is called
(ajd)

Extra validation on PLPKS config values (ruscur)

Return maxobjlabelsize to userspace as is without subtracting overhead (ruscur)

Fix error code handling in plpks_confirm_object_flushed() (ruscur)

Pass plpks_var struct to plpks_signed_update_var() by reference (mpe)

Make the data buffer in plpks_read_var() caller-allocated to reduce
number of allocations/copies (mpe)

Rework the Kconfig options so that PSERIES_PLPKS is a hidden option,
turned on by enabling PPC_SECURE_BOOT, and the PLPKS secvar code is
activated by PPC_SECVAR_SYSFS to match powernv (ajd)

Use machine_arch_initcall() rather than device_initcall() so we don't
break powernv (mpe)

Improve ABI documentation (mpe)

Return -EIO on most read errors (mpe)

Add "grubdbx" variable (Sudhakar)

Use utf8s_to_utf16s() rather than our own "UCS-2" conversion code (mpe)

Fix SB_VERSION data length (ruscur)

Stop prepending policy data on read (ruscur)

Don't print errors to the kernel log when reading non-existent
variables (Sudhakar)

Miscellaneous code style, checkpatch cleanups

Changes in v2:

Remove unnecessary config vars from sysfs and document the others,
thanks to review from Greg. If we end up needing to expose more, we
can add them later and update the docs.

Use sysfs_emit() instead of sprintf() for all sysfs strings

Change the size of the sysfs binary attributes to include the 8-byte
flags header, preventing truncation of large writes.

Andrew Donnellan (8):
powerpc/secvar: Clean up init error messages
powerpc/secvar: Allow backend to populate static list of variable
names
powerpc/secvar: Warn when PAGE_SIZE is smaller than max object size
powerpc/secvar: Don't print error on ENOENT when reading variables
powerpc/pseries: Fix handling of PLPKS object flushing timeout
powerpc/pseries: Fix alignment of PLPKS structures and buffers
powerpc/pseries: Make caller pass buffer to plpks_read_var()
powerpc/pseries: Turn PSERIES_PLPKS into a hidden option

Michael Ellerman (1):
powerpc/secvar: Use u64 in secvar_operations

Nayna Jain (2):
powerpc/pseries: Expose PLPKS config values, support additional fields
powerpc/pseries: Implement signed update for PLPKS objects

Russell Currey (13):
powerpc/secvar: WARN_ON_ONCE() if multiple secvar ops are set
powerpc/secvar: Use sysfs_emit() instead of sprintf()
powerpc/secvar: Handle format string in the consumer
powerpc/secvar: Handle max object size in the consumer
powerpc/secvar: Extend sysfs to include config vars
powerpc/pseries: Move plpks.h to include directory
powerpc/pseries: Move PLPKS constants to header file
powerpc/pseries: Log hcall return codes for PLPKS debug
powerpc/pseries: Add helpers to get PLPKS password
powerpc/pseries: Pass PLPKS password on kexec
powerpc/pseries: Implement secvars for dynamic secure boot
integrity/powerpc: Improve error handling & reporting when loading
certs
integrity/powerpc: Support loading keys from pseries secvar

Documentation/ABI/testing/sysfs-secvar | 75 +++-
arch/powerpc/Kconfig | 1 +
arch/powerpc/include/asm/hvcall.h | 3 +-
arch/powerpc/include/asm/plpks.h | 187 ++++++++++
arch/powerpc/include/asm/secvar.h | 19 +-
arch/powerpc/kernel/secvar-ops.c | 4 +-
arch/powerpc/kernel/secvar-sysfs.c | 168 +++++----
arch/powerpc/kexec/file_load_64.c | 17 +-
arch/powerpc/platforms/powernv/opal-secvar.c | 53 ++-
arch/powerpc/platforms/pseries/Kconfig | 11 +-
arch/powerpc/platforms/pseries/Makefile | 4 +-
arch/powerpc/platforms/pseries/plpks-secvar.c | 214 +++++++++++
arch/powerpc/platforms/pseries/plpks.c | 338 ++++++++++++++----
arch/powerpc/platforms/pseries/plpks.h | 71 ----
.../integrity/platform_certs/load_powerpc.c | 47 ++-
15 files changed, 965 insertions(+), 247 deletions(-)
create mode 100644 arch/powerpc/include/asm/plpks.h
create mode 100644 arch/powerpc/platforms/pseries/plpks-secvar.c
delete mode 100644 arch/powerpc/platforms/pseries/plpks.h

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2.39.0