Hello,

This is a refresh of the KEXEC_SIG series.

This adds KEXEC_SIG support on powerpc and deduplicates the code dealing
with appended signatures in the kernel.

powerpc supports IMA_KEXEC but that's an exception rather than the norm.
On the other hand, KEXEC_SIG is portable across platforms.

For distributions to have uniform security features across platforms one
option should be used on all platforms.

Thanks

Michal

Previous revision: https://lore.kernel.org/linuxppc-dev/cover.1637862358.git.msuchanek@suse.de/
Patched kernel tree: https://github.com/hramrach/kernel/tree/kexec_sig

Michal Suchanek (6):
  s390/kexec_file: Don't opencode appended signature check.
  powerpc/kexec_file: Add KEXEC_SIG support.
  kexec_file: Don't opencode appended signature verification.
  module: strip the signature marker in the verification function.
  module: Use key_being_used_for for log messages in
    verify_appended_signature
  module: Move duplicate mod_check_sig users code to mod_parse_sig

 arch/powerpc/Kconfig                     | 16 +++++++
 arch/powerpc/kexec/elf_64.c              | 12 +++++
 arch/s390/Kconfig                        |  2 +-
 arch/s390/kernel/machine_kexec_file.c    | 41 +----------------
 crypto/asymmetric_keys/asymmetric_type.c |  1 +
 include/linux/module_signature.h         |  4 +-
 include/linux/verification.h             |  5 ++
 kernel/module-internal.h                 |  2 -
 kernel/module.c                          | 12 ++---
 kernel/module_signature.c                | 58 +++++++++++++++++++++++-
 kernel/module_signing.c                  | 34 ++++++--------
 security/integrity/ima/ima_modsig.c      | 22 ++-------
 12 files changed, 119 insertions(+), 90 deletions(-)

-- 
2.31.1

Hi Michal,

On Tue, 2022-01-11 at 12:37 +0100, Michal Suchanek wrote:
> Hello,
> 
> This is a refresh of the KEXEC_SIG series.

> This adds KEXEC_SIG support on powerpc and deduplicates the code dealing
> with appended signatures in the kernel.
> 
> powerpc supports IMA_KEXEC but that's an exception rather than the norm.
> On the other hand, KEXEC_SIG is portable across platforms.

This Kconfig carries the IMA measurement list across kexec.  This has
nothing to do with appended signatures.

config IMA_KEXEC
        bool "Enable carrying the IMA measurement list across a soft
boot"
        depends on IMA && TCG_TPM && HAVE_IMA_KEXEC

In addition to powerpc, arm64 sets HAVE_IMA_KEXEC.

Even prior to the kexec appended signature support, like all other
files, the kexec kernel image signature could be stored in
security.ima.

> 
> For distributions to have uniform security features across platforms one
> option should be used on all platforms.

The kexec kernel image measurement will not be included in the BIOS
event log.  Even if the measurement is included in the IMA measurement
list, without the IMA_KEXEC Kconfig the measurement list will not be
carried across kexec.  For those not interested in "trusted boot" or
those who do not need it for compliance, the simplification should be
fine.

-- 
thanks,

Mimi

[Cc'ing  Nageswara R Sastry]

Hi Michal,

On Tue, 2022-01-11 at 12:37 +0100, Michal Suchanek wrote:
> Hello,
> 
> This is a refresh of the KEXEC_SIG series.
> 
> This adds KEXEC_SIG support on powerpc and deduplicates the code dealing
> with appended signatures in the kernel.

tools/testing/selftests/kexec/test_kexec_file_load.sh probably needs to
be updated to reflect the new Kconfig support.

FYI, commit 65e38e32a959 ("selftests/kexec: Enable secureboot tests for
PowerPC") recently was upstreamed.

-- 
thanks,

Mimi