[PATCH v6 0/9] powerpc: Enabling IMA arch specific secure boot policies

Nayna Jain
2019-09-27T14:26:22Z

This patchset extends the previous version of the patchset[1] by adding
the support for checking against the binary blacklisted hashes.

IMA subsystem supports custom, built-in, arch-specific policies to define
the files to be measured and appraised. These policies are honored based
on the priority where arch-specific policies is the highest and custom
is the lowest.

PowerNV systems uses the linux based bootloader and kexec the Host OS.
It rely on IMA for signature verification of the kernel before doing the
kexec. This patchset adds support for powerpc arch specific ima policies
that are defined based on system's OS secureboot and trustedboot state.
The OS secureboot and trustedboot state are determined via device-tree
properties.

The verification needs to be done only for the binaries which are not
blacklisted. The kernel currently checks against the blacklisted keys.
However that results in blacklisting all the binaries that are signed by
that key. In order to prevent single binary from loading, it is required
to support checking against blacklisting of the binary hash. This patchset
adds the support in IMA to check against blacklisted hashes for the files
signed by appended signature.

[1] http://patchwork.ozlabs.org/cover/1149262/

Changelog:
v6:
* includes feedbacks from Michael Ellerman on the patchset v5
* removed email ids from comments
* add the doc for the device-tree
* renames the secboot.c to secure_boot.c and secboot.h to secure_boot.h
* other code specific fixes
* split the patches to differentiate between secureboot and trustedboot
state of the system
* adds the patches to support the blacklisting of the binary hash.

v5:
* secureboot state is now read via device tree entry rather than OPAL
secure variables
* ima arch policies are updated to use policy based template for
measurement rules

v4:
* Fixed the build issue as reported by Satheesh Rajendran.

v3:
* OPAL APIs in Patch 1 are updated to provide generic interface based on
key/keylen. This patchset updates kernel OPAL APIs to be compatible with
generic interface.
* Patch 2 is cleaned up to use new OPAL APIs.
* Since OPAL can support different types of backend which can vary in the
variable interpretation, the Patch 2 is updated to add a check for the
backend version
* OPAL API now expects consumer to first check the supported backend version
before calling other secvar OPAL APIs. This check is now added in patch 2.
* IMA policies in Patch 3 is updated to specify appended signature and
per policy template.
* The patches now are free of any EFIisms.

v2:

* Removed Patch 1: powerpc/include: Override unneeded early ioremap
functions
* Updated Subject line and patch description of the Patch 1 of this series
* Removed dependency of OPAL_SECVAR on EFI, CPU_BIG_ENDIAN and UCS2_STRING
* Changed OPAL APIs from static to non-static. Added opal-secvar.h for the
same
* Removed EFI hooks from opal_secvar.c
* Removed opal_secvar_get_next(), opal_secvar_enqueue() and
opal_query_variable_info() function
* get_powerpc_sb_mode() in secboot.c now directly calls OPAL Runtime API
rather than via EFI hooks.
* Fixed log messages in get_powerpc_sb_mode() function.
* Added dependency for PPC_SECURE_BOOT on configs PPC64 and OPAL_SECVAR
* Replaced obj-$(CONFIG_IMA) with obj-$(CONFIG_PPC_SECURE_BOOT) in
arch/powerpc/kernel/Makefile

Nayna Jain (9):
dt-bindings: ibm,secureboot: secure boot specific properties for
PowerNV
powerpc: detect the secure boot mode of the system
powerpc: add support to initialize ima policy rules
powerpc: detect the trusted boot state of the system
powerpc/ima: add measurement rules to ima arch specific policy
ima: make process_buffer_measurement() non-static
ima: check against blacklisted hashes for files with modsig
ima: deprecate permit_directio, instead use appraise_flag
powerpc/ima: update ima arch policy to check for blacklist

Documentation/ABI/testing/ima_policy | 3 +-
.../bindings/powerpc/ibm,secureboot.rst | 76 +++++++++++++++
.../devicetree/bindings/powerpc/secvar.rst | 89 +++++++++++++++++
arch/powerpc/Kconfig | 12 +++
arch/powerpc/include/asm/secure_boot.h | 37 +++++++
arch/powerpc/kernel/Makefile | 2 +
arch/powerpc/kernel/ima_arch.c | 71 ++++++++++++++
arch/powerpc/kernel/secure_boot.c | 96 +++++++++++++++++++
include/linux/ima.h | 3 +-
security/integrity/ima/ima.h | 15 +++
security/integrity/ima/ima_appraise.c | 35 +++++++
security/integrity/ima/ima_main.c | 37 +++----
security/integrity/ima/ima_policy.c | 12 ++-
security/integrity/integrity.h | 1 +
14 files changed, 468 insertions(+), 21 deletions(-)
create mode 100644 Documentation/devicetree/bindings/powerpc/ibm,secureboot.rst
create mode 100644 Documentation/devicetree/bindings/powerpc/secvar.rst
create mode 100644 arch/powerpc/include/asm/secure_boot.h
create mode 100644 arch/powerpc/kernel/ima_arch.c
create mode 100644 arch/powerpc/kernel/secure_boot.c

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2.20.1