Enable gcc's -fstack-protector-all by default?

[Darren Tucker]

Hi all.

For a while, gcc has supported a stack protection mechanism
(-fstack-protector and friends, available in gcc 4.1.2 and up).

Can anyone think of a good reason not to enable it if the compiler
supports it?  A quick test here shows minimal difference in runtime over
a full regress pass (~10sec over 8.5 minutes, and since the machine is
not entirely idle that could be experimental error).

Index: configure.ac
===================================================================
RCS file: /usr/local/src/security/openssh/cvs/openssh/configure.ac,v
retrieving revision 1.386
diff -u -p -r1.386 configure.ac
--- configure.ac	26 Sep 2007 21:03:20 -0000	1.386
+++ configure.ac	26 Nov 2007 09:30:15 -0000
@@ -105,6 +105,15 @@ if test "$GCC" = "yes" || test "$GCC" = 
 		*) ;;
 	esac
 
+	AC_MSG_CHECKING(if $GCC understands -fstack-protector-all)
+	saved_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS -fstack-protector-all"
+	AC_TRY_COMPILE([], [ int main(void){return 0;} ],
+	    [ AC_MSG_RESULT(yes) ],
+	    [ AC_MSG_RESULT(no)
+	      CFLAGS="$saved_CFLAGS" ]
+	)
+
 	if test -z "$have_llong_max"; then
 		# retry LLONG_MAX with -std=gnu99, needed on some Linuxes
 		unset ac_cv_have_decl_LLONG_MAX

-- 
Darren Tucker (dtucker at zip.com.au)
GPG key 8FF4FA69 / D9A3 86E9 7EEE AF4B B2D4  37C9 C982 80C7 8FF4 FA69
    Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.