Add relro and now to hardening cflags, if available

Check ld for availability of relro and now flags and add them to the
hardening cflags if available.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>

diff --git a/configure.ac b/configure.ac
index 6fb4995e35da68d11c77ca6a65bca51df2eccfc2..f3b8a675a518d3c82f4f7c20eed5b5dea7dd19f2 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -135,7 +135,14 @@ AC_C_INLINE
 AC_TYPE_SIZE_T
 
 HARDENING_CFLAGS="-fstack-protector-strong -Wstack-protector "
-HARDENING_CFLAGS+="-D_FORTIFY_SOURCE=2"
+HARDENING_CFLAGS+="-D_FORTIFY_SOURCE=2 "
+dnl Check ld for 'relro' and 'now'
+if $LD --help 2>&1 | $GREP '\-z relro ' > /dev/null; then
+  HARDENING_CFLAGS+="-Wl,-z,relro "
+fi
+if $LD --help 2>&1 | $GREP '\-z now ' > /dev/null; then
+  HARDENING_CFLAGS+="-Wl,-z,now "
+fi
 AC_SUBST([HARDENING_CFLAGS])
 
 CFLAGS="$CFLAGS -Wall -Werror -Wreturn-type -Wsign-compare"