From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:39355) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RPy9c-0004O7-WC for qemu-devel@nongnu.org; Mon, 14 Nov 2011 10:09:02 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RPy9b-0006eC-Jq for qemu-devel@nongnu.org; Mon, 14 Nov 2011 10:09:00 -0500 Received: from mail-yw0-f45.google.com ([209.85.213.45]:58507) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RPy9b-0006e2-A5 for qemu-devel@nongnu.org; Mon, 14 Nov 2011 10:08:59 -0500 Received: by ywa17 with SMTP id 17so2834689ywa.4 for ; Mon, 14 Nov 2011 07:08:58 -0800 (PST) Message-ID: <4EC12F07.7020801@codemonkey.ws> Date: Mon, 14 Nov 2011 09:08:55 -0600 From: Anthony Liguori MIME-Version: 1.0 References: <1321281869-4280-1-git-send-email-avi@redhat.com> In-Reply-To: <1321281869-4280-1-git-send-email-avi@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 1.0] configure: build position independent executables across the board, by default List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: Blue Swirl , Paul Moore , qemu-devel@nongnu.org On 11/14/2011 08:44 AM, Avi Kivity wrote: > Change the default to building PIE (position independent executables); instead > of restricting the option to user-only targets, apply it to all targets. > > In addition, set the relocation sections to read-only (relro) when available; > this reduces the attack surface by disallowing changes to relocation tables > at runtime. > > While PIE reduces performance and relro increases load time, it greatly > improves security, with the potential to reduce a code execution vulnerability > to a self denial of service. > > Signed-off-by: Avi Kivity > --- > > v2: improves description to include relro > > While we are past the feature freeze, I feel this deserves an exception. I'm inclined to agree. I don't want to put this in -rc2 since there's not enough time to test it, but I'll start testing it tomorrow and we can try to do it by -rc3. Regards, Anthony Liguori > I'd > much rather see "CVE-2012-wxyz QEMU Self denial of service" than > "CVE-2012-wxyz QEMU code execution". The fact that the option is available > for user targets implies that it is compatible with TCG, and some light testing > agrees. > > configure | 35 +++++++++++++++++------------------ > 1 files changed, 17 insertions(+), 18 deletions(-) > > diff --git a/configure b/configure > index 6c77fbb..7436361 100755 > --- a/configure > +++ b/configure > @@ -172,7 +172,7 @@ aix="no" > blobs="yes" > pkgversion="" > check_utests="" > -user_pie="no" > +pie="yes" > zero_malloc="" > trace_backend="nop" > trace_file="trace" > @@ -701,9 +701,9 @@ for opt do > ;; > --disable-guest-base) guest_base="no" > ;; > - --enable-user-pie) user_pie="yes" > + --enable-pie) pie="yes" > ;; > - --disable-user-pie) user_pie="no" > + --disable-pie) pie="no" > ;; > --enable-uname-release=*) uname_release="$optarg" > ;; > @@ -1031,8 +1031,8 @@ echo " --disable-bsd-user disable all BSD usermode emulation targets" > echo " --enable-guest-base enable GUEST_BASE support for usermode" > echo " emulation targets" > echo " --disable-guest-base disable GUEST_BASE support" > -echo " --enable-user-pie build usermode emulation targets as PIE" > -echo " --disable-user-pie do not build usermode emulation targets as PIE" > +echo " --enable-pie build Position Independent Executables" > +echo " --disable-pie do not build Position Independent Executables" > echo " --fmod-lib path to FMOD library" > echo " --fmod-inc path to FMOD includes" > echo " --oss-lib path to OSS library" > @@ -1099,6 +1099,17 @@ for flag in $gcc_flags; do > fi > done > > +if test "$pie" = "yes" ; then > + QEMU_CFLAGS="-fPIE -DPIE $QEMU_CFLAGS" > + LDFLAGS="-Wl,-pie $LDFLAGS" > + cat> $TMPC<< EOF > +int main(void) { return 0; } > +EOF > + if compile_prog "-fPIE -DPIE" "-Wl,-pie -Wl,-z,relro -Wl,-z,now"; then > + LDFLAGS="-Wl,-z,relro -Wl,-z,now $LDFLAGS" > + fi > +fi > + > # > # Solaris specific configure tool chain decisions > # > @@ -2765,7 +2776,7 @@ echo "Documentation $docs" > echo "uname -r $uname_release" > echo "NPTL support $nptl" > echo "GUEST_BASE $guest_base" > -echo "PIE user targets $user_pie" > +echo "PIE $pie" > echo "vde support $vde" > echo "Linux AIO support $linux_aio" > echo "ATTR/XATTR support $attr" > @@ -3225,9 +3236,6 @@ for d in libdis libdis-user; do > symlink $source_path/Makefile.dis $d/Makefile > echo> $d/config.mak > done > -if test "$static" = "no" -a "$user_pie" = "yes" ; then > - echo "QEMU_CFLAGS+=-fpie"> libdis-user/config.mak > -fi > > for target in $target_list; do > target_dir="$target" > @@ -3646,12 +3654,6 @@ if test "$target_softmmu" = "yes" ; then > esac > fi > > -if test "$target_user_only" = "yes" -a "$static" = "no" -a \ > - "$user_pie" = "yes" ; then > - cflags="-fpie $cflags" > - ldflags="-pie $ldflags" > -fi > - > if test "$target_softmmu" = "yes" -a \( \ > "$TARGET_ARCH" = "microblaze" -o \ > "$TARGET_ARCH" = "cris" \) ; then > @@ -3775,9 +3777,6 @@ d=libuser > mkdir -p $d > mkdir -p $d/trace > symlink $source_path/Makefile.user $d/Makefile > -if test "$static" = "no" -a "$user_pie" = "yes" ; then > - echo "QEMU_CFLAGS+=-fpie"> $d/config.mak > -fi > > if test "$docs" = "yes" ; then > mkdir -p QMP