[PATCH] prevent kernel address space leak via dmesg or /proc files

["Peter Müller" <peter.mueller@link38.eu>]

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Enable runtime sysctl hardening in order to avoid kernel
addresses being disclosed via dmesg (in case it was built
in without restrictions) or various /proc files.

See https://kernsec.org/wiki/index.php/Kernel_Self_Protection_Project/Recommended_Settings
for further information.

Signed-off-by: Peter Müller <peter.mueller(a)ipfire.org>
---
 setup/setup.nm                     | 2 ++
 setup/sysctl/kernel-hardening.conf | 6 ++++++
 2 files changed, 8 insertions(+)
 create mode 100644 setup/sysctl/kernel-hardening.conf

diff --git a/setup/setup.nm b/setup/setup.nm
index 78d1a5df3..f1dd3c177 100644
--- a/setup/setup.nm
+++ b/setup/setup.nm
@@ -53,6 +53,8 @@ build
 			%{BUILDROOT}%{sysconfdir}/sysctl.d/printk.conf
 		install -m 644 %{DIR_APP}/sysctl/swappiness.conf \
 			%{BUILDROOT}%{sysconfdir}/sysctl.d/swappiness.conf
+		install -m 644 %{DIR_APP}/sysctl/kernel-hardening.conf \
+			%{BUILDROOT}%{sysconfdir}/sysctl.d/kernel-hardening.conf
 	end
 end
 
diff --git a/setup/sysctl/kernel-hardening.conf b/setup/sysctl/kernel-hardening.conf
new file mode 100644
index 000000000..6751bbef6
--- /dev/null
+++ b/setup/sysctl/kernel-hardening.conf
@@ -0,0 +1,6 @@
+# Try to keep kernel address exposures out of various /proc files (kallsyms, modules, etc).
+kernel.kptr_restrict = 1
+
+# Avoid kernel memory address exposures via dmesg.
+kernel.dmesg_restrict = 1
+
-- 
2.16.4