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Merge branch 'madaidan-kernel-hardening'

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Patrick Schleizer 2019-12-23 03:38:04 -05:00
commit b05669accf
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2 changed files with 43 additions and 9 deletions
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12
debian/control vendored
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@ -56,7 +56,9 @@ Description: enhances misc security settings
* Slab merging is disabled as sometimes a slab can be used in a vulnerable
way which an attacker can exploit.
.
* Sanity checks, redzoning, and memory poisoning are enabled.
* Sanity checks and redzoning are enabled.
.
* Memory zeroing at allocation and free time is enabled.
.
* Machine checks (MCE) are disabled which makes the kernel panic
on uncorrectable errors in ECC memory that could be exploited.
@ -106,6 +108,14 @@ Description: enhances misc security settings
.
* The MSR kernel module is blacklisted to prevent CPU MSRs from being
abused to write to arbitrary memory.
.
* Vsyscalls are disabled as they are obsolete, are at fixed addresses and are
a target for ROP.
.
* Page allocator freelist randomization is enabled.
.
* Kernel lockdown is enabled.
.
.
Improve Entropy Collection
.

40
etc/default/grub.d/40_kernel_hardening.cfg
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@ -1,18 +1,29 @@
## Copyright (C) 2019 - 2019 ENCRYPTED SUPPORT LP <adrelanos@riseup.net>
## See the file COPYING for copying conditions.
## Disables the merging of slabs of similar sizes. Sometimes a slab can be used in a vulnerable way which an attacker can exploit.
kver="$(uname -r)"
## Disables the merging of slabs of similar sizes.
## Sometimes a slab can be used in a vulnerable way which an attacker can exploit.
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX slab_nomerge"
## Enables sanity checks (F), redzoning (Z) and poisoning (P).
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX slub_debug=FZP"
## Enables sanity checks (F) and redzoning (Z).
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX slub_debug=FZ"
if command -v "qubesdb-read" >/dev/null 2>&1 ; then
## https://github.com/QubesOS/qubes-issues/issues/5212#issuecomment-533873012
true "skip adding page_poison=1 in Qubes"
## Zero memory at allocation and free time.
if dpkg --compare-versions "${kver}" ge "5.3"; then
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX init_on_alloc=1 init_on_free=1"
else
## Wipes free memory so it can't leak in various ways and prevents some use-after-free vulnerabilites.
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX page_poison=1"
## SLUB poisoning and page poisoning is used if the kernel
## does not yet support init_on_{,alloc,free}.
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX slub_debug=P"
if command -v "qubesdb-read" >/dev/null 2>&1 ; then
## https://github.com/QubesOS/qubes-issues/issues/5212#issuecomment-533873012
true "skip adding page_poison=1 in Qubes"
else
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX page_poison=1"
fi
fi
## Makes the kernel panic on uncorrectable errors in ECC memory that an attacker could exploit.
@ -24,3 +35,16 @@ GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX pti=on"
## Enables all mitigations for the MDS vulnerability.
## Disables smt which can be used to exploit the MDS vulnerability.
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX mds=full,nosmt"
## Vsyscalls are obsolete, are at fixed addresses and are a target for ROP.
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX vsyscall=none"
## Enables page allocator freelist randomization.
if dpkg --compare-versions "${kver}" ge "5.2"; then
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX page_alloc.shuffle=1"
fi
## Enables kernel lockdown.
if dpkg --compare-versions "${kver}" ge "5.4"; then
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX lockdown=confidentiality"
fi