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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