[PATCHC v7 00/10] ima: carry the measurement list across kexec

Mimi Zohar zohar at linux.vnet.ibm.com
Fri Nov 11 01:56:10 AEDT 2016

[Posting with abbreviated Cc list.]

The TPM PCRs are only reset on a hard reboot.  In order to validate a
TPM's quote after a soft reboot (eg. kexec -e), the IMA measurement list
of the running kernel must be saved and then restored on the subsequent
boot, possibly of a different architecture.

The existing securityfs binary_runtime_measurements file conveniently
provides a serialized format of the IMA measurement list. This patch
set serializes the measurement list in this format and restores it.

Up to now, the binary_runtime_measurements was defined as architecture
native format.  The assumption being that userspace could and would
handle any architecture conversions.  With the ability of carrying the
measurement list across kexec, possibly from one architecture to a
different one, the per boot architecture information is lost and with it
the ability of recalculating the template digest hash.  To resolve this
problem, without breaking the existing ABI, this patch set introduces
the boot command line option "ima_canonical_fmt", which is arbitrarily
defined as little endian.

The need for this boot command line option will be limited to the
existing version 1 format of the binary_runtime_measurements.
Subsequent formats will be defined as canonical format (eg. TPM 2.0
support for larger digests).

A simplified method of Thiago Bauermann's "kexec buffer handover" patch
series for carrying the IMA measurement list across kexec is included
in this patch set.  The simplified method requires all file measurements
be taken prior to executing the kexec load, as subsequent measurements
will not be carried across the kexec and restored.

These patches can also be found in the next-kexec-restore branch of:

Changelog v7:
- Updated to reflect Dmitry Kasatkin's patch review
- Rebased on top of "next-fixes" branch

Andreas Steffen (1):
  ima: platform-independent hash value

Mimi Zohar (7):
  ima: on soft reboot, restore the measurement list
  ima: permit duplicate measurement list entries
  ima: maintain memory size needed for serializing the measurement list
  ima: on soft reboot, save the measurement list
  ima: store the builtin/custom template definitions in a list
  ima: support restoring multiple template formats
  ima: define a canonical binary_runtime_measurements list format

Thiago Jung Bauermann (2):
  powerpc: ima: Get the kexec buffer passed by the previous kernel
  powerpc: ima: Send the kexec buffer to the next kernel

 Documentation/kernel-parameters.txt         |   4 +
 arch/Kconfig                                |   3 +
 arch/powerpc/Kconfig                        |   1 +
 arch/powerpc/include/asm/ima.h              |  29 +++
 arch/powerpc/include/asm/kexec.h            |  15 +-
 arch/powerpc/kernel/Makefile                |   4 +
 arch/powerpc/kernel/ima_kexec.c             | 223 +++++++++++++++++++++
 arch/powerpc/kernel/kexec_elf_64.c          |   2 +-
 arch/powerpc/kernel/machine_kexec_file_64.c |  15 +-
 include/linux/ima.h                         |  12 ++
 kernel/kexec_file.c                         |   4 +
 security/integrity/ima/Kconfig              |  12 ++
 security/integrity/ima/Makefile             |   1 +
 security/integrity/ima/ima.h                |  31 +++
 security/integrity/ima/ima_crypto.c         |   6 +-
 security/integrity/ima/ima_fs.c             |  30 ++-
 security/integrity/ima/ima_init.c           |   2 +
 security/integrity/ima/ima_kexec.c          | 168 ++++++++++++++++
 security/integrity/ima/ima_main.c           |   1 +
 security/integrity/ima/ima_queue.c          |  77 +++++++-
 security/integrity/ima/ima_template.c       | 297 ++++++++++++++++++++++++++--
 security/integrity/ima/ima_template_lib.c   |   7 +-
 22 files changed, 906 insertions(+), 38 deletions(-)
 create mode 100644 arch/powerpc/include/asm/ima.h
 create mode 100644 arch/powerpc/kernel/ima_kexec.c
 create mode 100644 security/integrity/ima/ima_kexec.c


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