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Message-Id: <20190907061124.1947-1-cmr@informatik.wtf>
Date: Sat, 7 Sep 2019 01:11:22 -0500
From: "Christopher M. Riedl" <cmr@...ormatik.wtf>
To: linuxppc-dev@...abs.org,
kernel-hardening@...ts.openwall.com
Cc: ajd@...ux.ibm.com,
dja@...ens.net
Subject: [PATCH v7 0/2] Restrict xmon when kernel is locked down
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 and cleared using xmon.
Changes since v6:
- Add lockdown check in sysrq-trigger to prevent entry into xmon_core
- Add lockdown check during init xmon setup for the case when booting
with compile-time or cmdline lockdown=confidentialiaty
Changes since v5:
- Do not spam print messages when attempting to enter xmon when
lockdown=confidentiality
Changes since v4:
- Move lockdown state checks into xmon_core
- Allow clearing of breakpoints in xmon read-only mode
- Test simple scenarios (combinations of xmon and lockdown cmdline
options, setting breakpoints and changing lockdown state, etc) in
QEMU and on an actual POWER8 VM
- Rebase onto security/next-lockdown
b602614a81078bf29c82b2671bb96a63488f68d6
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 and clearing breakpoints in read-only mode
powerpc/xmon: Restrict when kernel is locked down
arch/powerpc/xmon/xmon.c | 119 +++++++++++++++++++++++++++--------
include/linux/security.h | 2 +
security/lockdown/lockdown.c | 2 +
3 files changed, 97 insertions(+), 26 deletions(-)
--
2.23.0
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