[PATCH v5 0/4] powerpc: expose secure variables to the kernel and userspace

From: Nayna Jain
Date: Thu Oct 24 2019 - 20:47:46 EST

In order to verify the OS kernel on PowerNV systems, secure boot requires
X.509 certificates trusted by the platform. These are stored in secure
variables controlled by OPAL, called OPAL secure variables. In order to
enable users to manage the keys, the secure variables need to be exposed
to userspace.

OPAL provides the runtime services for the kernel to be able to access the
secure variables[1]. This patchset defines the kernel interface for the
OPAL APIs. These APIs are used by the hooks, which load these variables
to the keyring and expose them to the userspace for reading/writing.

The previous version[2] of the patchset added support only for the sysfs
interface. This patch adds two more patches that involves loading of
the firmware trusted keys to the kernel keyring.

Overall, this patchset adds the following support:

* expose secure variables to the kernel via OPAL Runtime API interface
* expose secure variables to the userspace via kernel sysfs interface
* load kernel verification and revocation keys to .platform and
.blacklist keyring respectively.

The secure variables can be read/written using simple linux utilities

For example:
Path to the secure variables is:

Each secure variable is listed as directory.
$ ls -l
total 0
drwxr-xr-x. 2 root root 0 Aug 20 21:20 db
drwxr-xr-x. 2 root root 0 Aug 20 21:20 KEK
drwxr-xr-x. 2 root root 0 Aug 20 21:20 PK

The attributes of each of the secure variables are(for example: PK):
[db]$ ls -l
total 0
-r--r--r--. 1 root root 4096 Oct 1 15:10 data
-r--r--r--. 1 root root 65536 Oct 1 15:10 size
--w-------. 1 root root 4096 Oct 1 15:12 update

The "data" is used to read the existing variable value using hexdump. The
data is stored in ESL format.
The "update" is used to write a new value using cat. The update is
to be submitted as AUTH file.

[1] Depends on skiboot OPAL API changes which removes metadata from
the API. https://lists.ozlabs.org/pipermail/skiboot/2019-September/015203.html.
[2] https://lkml.org/lkml/2019/6/13/1644

* rebased to v5.4-rc3
* includes Oliver's feedbacks
* changed OPAL API as platform driver
* sysfs are made default enabled and dependent on PPC_SECURE_BOOT
* fixed code specific changes in both OPAL API and sysfs
* reading size of the "data" and "update" file from device-tree.
* fixed sysfs documentation to also reflect the data and update file
size interpretation
* This patchset is no more dependent on ima-arch/blacklist patchset

* rebased to v5.4-rc1
* uses __BIN_ATTR_WO macro to create binary attribute as suggested by
* removed email id from the file header
* renamed argument keysize to keybufsize in get_next() function
* updated default binary file sizes to 0, as firmware handles checking
against the maximum size
* fixed minor formatting issues in Patch 4/4
* added Greg's and Mimi's Reviewed-by and Ack-by

* includes Greg's feedbacks:
* fixes in Patch 2/4
* updates the Documentation.
* fixes code feedbacks
* adds SYSFS Kconfig dependency for SECVAR_SYSFS
* fixes mixed tabs and spaces
* removes "name" attribute for each of the variable name based
* fixes using __ATTR_RO() and __BIN_ATTR_RO() and statics and const
* fixes the racing issue by using kobj_type default groups. Also,
fixes the kobject leakage.
* removes extra print messages
* updates patch description for Patch 3/4
* removes file name from Patch 4/4 file header comment and removed
def_bool y from the LOAD_PPC_KEYS Kconfig

* includes Oliver's feedbacks:
* fixes Patch 1/2
* moves OPAL API wrappers after opal_nx_proc_init(), fixed the
naming, types and removed extern.
* fixes spaces
* renames get_variable() to get(), get_next_variable() to get_next()
and set_variable() to set()
* removed get_secvar_ops() and defined secvar_ops as global
* fixes consts and statics
* removes generic secvar_init() and defined platform specific
* updates opal_secvar_supported() to check for secvar support even
before checking the OPAL APIs support and also fixed the error codes.
* addes function that converts OPAL return codes to linux errno
* moves secvar check support in the opal_secvar_init() and defined its
prototype in opal.h
* fixes Patch 2/2
* fixes static/const
* defines macro for max name size
* replaces OPAL error codes with linux errno and also updated error
* moves secvar support check before creating sysfs kobjects in
* fixes spaces

* removes complete efi-sms from the sysfs implementation and is simplified
* includes Greg's and Oliver's feedbacks:
* adds sysfs documentation
* moves sysfs code to arch/powerpc
* other code related feedbacks.
* adds two new patches to load keys to .platform and .blacklist keyring.
These patches are added to this series as they are also dependent on

Nayna Jain (4):
powerpc/powernv: Add OPAL API interface to access secure variable
powerpc: expose secure variables to userspace via sysfs
x86/efi: move common keyring handler functions to new file
powerpc: load firmware trusted keys/hashes into kernel keyring

Documentation/ABI/testing/sysfs-secvar | 39 +++
arch/powerpc/Kconfig | 12 +
arch/powerpc/include/asm/opal-api.h | 5 +-
arch/powerpc/include/asm/opal.h | 7 +
arch/powerpc/include/asm/secvar.h | 35 +++
arch/powerpc/kernel/Makefile | 3 +-
arch/powerpc/kernel/secvar-ops.c | 16 ++
arch/powerpc/kernel/secvar-sysfs.c | 228 ++++++++++++++++++
arch/powerpc/platforms/powernv/Makefile | 2 +-
arch/powerpc/platforms/powernv/opal-call.c | 3 +
arch/powerpc/platforms/powernv/opal-secvar.c | 140 +++++++++++
arch/powerpc/platforms/powernv/opal.c | 3 +
security/integrity/Kconfig | 8 +
security/integrity/Makefile | 7 +-
.../platform_certs/keyring_handler.c | 80 ++++++
.../platform_certs/keyring_handler.h | 32 +++
.../integrity/platform_certs/load_powerpc.c | 86 +++++++
security/integrity/platform_certs/load_uefi.c | 67 +----
18 files changed, 702 insertions(+), 71 deletions(-)
create mode 100644 Documentation/ABI/testing/sysfs-secvar
create mode 100644 arch/powerpc/include/asm/secvar.h
create mode 100644 arch/powerpc/kernel/secvar-ops.c
create mode 100644 arch/powerpc/kernel/secvar-sysfs.c
create mode 100644 arch/powerpc/platforms/powernv/opal-secvar.c
create mode 100644 security/integrity/platform_certs/keyring_handler.c
create mode 100644 security/integrity/platform_certs/keyring_handler.h
create mode 100644 security/integrity/platform_certs/load_powerpc.c