Add auditd package and systemd unit

This includes the `auditd` binary and systemd unit as part of the
distro. While journald is also able to handle logs from the linux audit
subsystem, auditd provides audit-specific capabilities that are
necessary in deployments subject to regulatory compliance.

For one, an administrator is able to configure audit log writing policy
to ensure that logs land on disk and nothing is missed (`flush`). We
wouldn't want such policy through journald as it woudl sync and ensure
all logs which might be undesirable and too resource intensive. In
short, this allows us to configure different management policies for
audit logs compared to general logs.

It allows us to explicitly configure the node's reaction to errors such
as the disk beign full, the disk having other issues or space constraints.

While Flatcar is not Common Criteria certified which would require the
system to shut down if audit logs present issues (not written or
collected), some FedRAMP environments do require actions such as
notifications (which could be achieved via syslog). This can be
explicitly done with auditd as well.

Co-authored-by: Kai Lüke <pothos@users.noreply.github.com>

sdk_container/src/third_party/coreos-overlay/sys-process/audit/audit-3.0.6.ebuild

@@ -42,17 +42,13 @@ src_prepare() {
 	# Disable installing sample rules so they can be installed as docs.
 	echo -e '%:\n\t:' | tee rules/Makefile.{am,in} >/dev/null
 
-	# Flatcar: Do not build daemon stuff.
-	sed -e '/^SUBDIRS =/s/audisp//' \
-		-i Makefile.am || die
 	# Flatcar: Some legacy stuff is being installed when systemd
 	# is enabled. Drop all the lines that try doing it.
 	sed -e '/${DESTDIR}${initdir}/d' \
 		-e '/${DESTDIR}${legacydir}/d' \
 		-i init.d/Makefile.am || die
 	# Flatcar: Do not build daemon stuff.
-	sed -e '/^sbin_PROGRAMS =/s/auditd//' \
-		-e '/^sbin_PROGRAMS =/s/aureport//' \
+	sed -e '/^sbin_PROGRAMS =/s/aureport//' \
 		-e '/^sbin_PROGRAMS =/s/ausearch//' \
 		-i src/Makefile.am || die
 
@@ -144,6 +140,11 @@ multilib_src_install_all() {
 	# newinitd "${FILESDIR}"/auditd-init.d-2.4.3 auditd
 	# newconfd "${FILESDIR}"/auditd-conf.d-2.1.3 auditd
 
+	# Flatcar: install sample configuration
+	insinto /usr/share/auditd
+	doins "${S}"/init.d/auditd.conf
+
+
 	# Flatcar: We are not installing audisp too.
 	# [ -f "${ED}"/sbin/audisp-remote ] && \
 	# dodir /usr/sbin && \
@@ -151,7 +152,6 @@ multilib_src_install_all() {
 
 	# Flatcar: Do not install gentoo rules.
 	# Gentoo rules
-	# insinto /etc/audit
 	# newins "${FILESDIR}"/audit.rules-2.1.3 audit.rules
 	# Flatcar: We are installing our own rules.
 	insinto /usr/share/audit/rules.d
@@ -160,15 +160,16 @@ multilib_src_install_all() {
 	# doins "${FILESDIR}"/audit.rules.stop*
 
 	# audit logs go here
-	# Flatcar: This is where auditd puts its logs. We don't have
-	# the daemon, so get rid of the unnecessary directory.
-	# keepdir /var/log/audit
+	keepdir /var/log/audit
 
 	find "${ED}" -type f -name '*.la' -delete || die
 
 	# Security
 	lockdown_perms "${ED}"
 
+	# Flatcar: We add the systemd unit but don't enable it.
+	systemd_dounit init.d/auditd.service
+
 	# Flatcar: Our systemd stuff.
 	newtmpfiles "${FILESDIR}"/audit-rules.tmpfiles audit-rules.conf
 	systemd_dounit "${FILESDIR}"/audit-rules.service
@@ -182,11 +183,13 @@ pkg_postinst() {
 lockdown_perms() {
 	# Upstream wants these to have restrictive perms.
 	# Should not || die as not all paths may exist.
-	# Flatcar: No lockdown of permissions - it's probably only
-	# related to auditd.
-	# local basedir="${1}"
+	# Flatcar: We don't include ausearch and aureport
+	# so they're removed from the hardening list
+	local basedir="${1}"
 	# chmod 0750 "${basedir}"/sbin/au{ditctl,ditd,report,search,trace} 2>/dev/null
-	# chmod 0750 "${basedir}"/var/log/audit 2>/dev/null
+	chmod 0750 "${basedir}"/sbin/au{ditctl,ditd,trace} 2>/dev/null
+	chmod 0750 "${basedir}"/var/log/audit 2>/dev/null
 	# chmod 0640 "${basedir}"/etc/audit/{auditd.conf,audit*.rules*} 2>/dev/null
+	rm -f  "${basedir}"/etc/audit/auditd.conf 2>/dev/null
 	:
 }

sdk_container/src/third_party/coreos-overlay/sys-process/audit/files/audit-rules.tmpfiles

@@ -1,5 +1,6 @@
-d   /etc/audit                          -   -   -   -   -
-d   /etc/audit/rules.d                  -   -   -   -   -
-L   /etc/audit/rules.d/00-clear.rules   -   -   -   -   /usr/share/audit/rules.d/00-clear.rules
-L   /etc/audit/rules.d/80-selinux.rules -   -   -   -   /usr/share/audit/rules.d/80-selinux.rules
-L   /etc/audit/rules.d/99-default.rules -   -   -   -   /usr/share/audit/rules.d/99-default.rules
+d   /etc/audit                          750   -   -   -   -
+C   /etc/audit/auditd.conf              640  -   -   -   /usr/share/auditd/auditd.conf
+d   /etc/audit/rules.d                  750   -   -   -   -
+L   /etc/audit/rules.d/00-clear.rules   640   -   -   -   /usr/share/audit/rules.d/00-clear.rules
+L   /etc/audit/rules.d/80-selinux.rules 640   -   -   -   /usr/share/audit/rules.d/80-selinux.rules
+L   /etc/audit/rules.d/99-default.rules 640   -   -   -   /usr/share/audit/rules.d/99-default.rules