configure: Add option to link against libselinux

configure.ac

@@ -321,6 +321,7 @@ ARG_ENABL_SET([python-eggs],    [enable build of provided python eggs.])
 ARG_ENABL_SET([python-eggs-install],[enable installation of provided python eggs.])
 ARG_ENABL_SET([perl-cpan],      [enable build of provided perl CPAN module.])
 ARG_ENABL_SET([perl-cpan-install],[enable installation of provided CPAN module.])
+ARG_ENABL_SET([selinux],        [enable SELinux support for labeled IPsec.])
 ARG_ENABL_SET([tss-trousers],   [enable the use of the TrouSerS Trusted Software Stack])
 ARG_ENABL_SET([tss-tss2],       [enable the use of the TSS 2.0 Trusted Software Stack])
 
@@ -1248,6 +1249,13 @@ if test x$capabilities = xlibcap; then
 	AC_DEFINE([CAPABILITIES_LIBCAP], [], [have libpcap library])
 fi
 
+if test x$selinux = xtrue; then
+	PKG_CHECK_MODULES(selinux, [libselinux])
+	AC_SUBST(selinux_CFLAGS)
+	AC_SUBST(selinux_LIBS)
+	AC_DEFINE([USE_SELINUX], [], [build with support for SELinux])
+fi
+
 if test x$integrity_test = xtrue; then
 	AC_MSG_CHECKING([for dladdr()])
 	AC_COMPILE_IFELSE(

scripts/test.sh

@@ -171,7 +171,8 @@ all|coverage|sonarcloud)
 	DEPS="$DEPS libcurl4-gnutls-dev libsoup2.4-dev libunbound-dev libldns-dev
 		  libmysqlclient-dev libsqlite3-dev clearsilver-dev libfcgi-dev
 		  libldap2-dev libpcsclite-dev libpam0g-dev binutils-dev libnm-dev
-		  libgcrypt20-dev libjson-c-dev python3-pip libtspi-dev libsystemd-dev"
+		  libgcrypt20-dev libjson-c-dev python3-pip libtspi-dev libsystemd-dev
+		  libselinux1-dev"
 	if [ "$ID" = "ubuntu" -a "$VERSION_ID" = "20.04" ]; then
 		DEPS="$DEPS libiptc-dev"
 	else

src/libstrongswan/Makefile.am

@@ -132,7 +132,8 @@ library.lo :	$(top_builddir)/config.status
 
 libstrongswan_la_LIBADD = \
 	$(DLLIB) $(ATOMICLIB)  $(BTLIB) $(SOCKLIB) \
-	$(RTLIB) $(BFDLIB) $(UNWINDLIB)
+	$(RTLIB) $(BFDLIB) $(UNWINDLIB) \
+	$(selinux_LIBS)
 
 AM_CPPFLAGS = \
 	-I$(top_srcdir)/src/libstrongswan \
@@ -142,6 +143,7 @@ AM_CPPFLAGS = \
 	-DSTRONGSWAN_CONF=\"${strongswan_conf}\"
 
 AM_CFLAGS = \
+	$(selinux_CFLAGS) \
 	@COVERAGE_CFLAGS@
 
 AM_LDFLAGS = \