[RFC,v4,0/2] Restrict xmon when kernel is locked down

Message

Christopher M. Riedl Aug. 15, 2019, 5:06 a.m. UTC

Xmon should be either fully or partially disabled depending on the
kernel lockdown state.

Put xmon into read-only mode for lockdown=integrity and completely
disable xmon when lockdown=confidentiality. Since this can occur
dynamically, there may be pre-existing, active breakpoints in xmon when
transitioning into read-only mode. These breakpoints will still trigger,
so allow them to be listed, but not cleared or altered, using xmon.

Changes since v3:
 - Allow active breakpoints to be shown/listed in read-only mode

Changes since v2:
 - Rebased onto v36 of https://patchwork.kernel.org/cover/11049461/
   (based on: f632a8170a6b667ee4e3f552087588f0fe13c4bb)
 - Do not clear existing breakpoints when transitioning from
   lockdown=none to lockdown=integrity
 - Remove line continuation and dangling quote (confuses checkpatch.pl)
   from the xmon command help/usage string

Christopher M. Riedl (2):
  powerpc/xmon: Allow listing active breakpoints in read-only mode
  powerpc/xmon: Restrict when kernel is locked down

 arch/powerpc/xmon/xmon.c     | 78 ++++++++++++++++++++++++++++++++----
 include/linux/security.h     |  2 +
 security/lockdown/lockdown.c |  2 +
 3 files changed, 74 insertions(+), 8 deletions(-)