From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:57069) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RSeNn-0004PV-Uu for qemu-devel@nongnu.org; Mon, 21 Nov 2011 19:38:45 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RSe8B-00030u-Hw for qemu-devel@nongnu.org; Mon, 21 Nov 2011 19:22:43 -0500 Received: from mail-gy0-f173.google.com ([209.85.160.173]:46676) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RSe8B-0002zy-DL for qemu-devel@nongnu.org; Mon, 21 Nov 2011 19:22:35 -0500 Received: by ghbg19 with SMTP id g19so3015965ghb.4 for ; Mon, 21 Nov 2011 16:22:16 -0800 (PST) Message-ID: <4ECAEB36.2020601@codemonkey.ws> Date: Mon, 21 Nov 2011 18:22:14 -0600 From: Anthony Liguori MIME-Version: 1.0 References: <1321380737-23007-1-git-send-email-avi@redhat.com> In-Reply-To: <1321380737-23007-1-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 v8 1.0] configure: build position independent executables on x86-Linux hosts List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: Blue Swirl , Paul Moore , qemu-devel@nongnu.org, Peter Maydell On 11/15/2011 12:12 PM, Avi Kivity wrote: > Change the default on x86 Linux hosts 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. > > Non-x86 are not changed, as they require TCG changes; neither are > non-Linux, due to lack of test coverage. > > Signed-off-by: Avi Kivity Applied. Thanks. Regards, Anthony Liguori > --- > > v8: restrict further to Linux hosts > use linker option '-pie' instead of '-Wl,-pie'; fixes link on x86_64 > > v7: avoid 'test -a' > optimize relro/now linker flag test > fail if toolchain doesn't support pie while the user explicitly asked for it > > v6: fix subject line. sigh. > > v5: fix typos; only default enable for x86; mutually exclusive with -static > > v4: say it's v4 and for 1.0 > > v3: detect toolchain support for PIE at configure time > > v2: improve description to include relro > > configure | 65 ++++++++++++++++++++++++++++++++++++++++++++---------------- > 1 files changed, 47 insertions(+), 18 deletions(-) > > diff --git a/configure b/configure > index 6c77fbb..75e1f10 100755 > --- a/configure > +++ b/configure > @@ -172,7 +172,7 @@ aix="no" > blobs="yes" > pkgversion="" > check_utests="" > -user_pie="no" > +pie="" > 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 +1099,47 @@ for flag in $gcc_flags; do > fi > done > > +if test "$static" = "yes" ; then > + if test "$pie" = "yes" ; then > + echo "static and pie are mutually incompatible" > + exit 1 > + else > + pie="no" > + fi > +fi > + > +if test "$pie" = ""; then > + case "$cpu-$targetos" in > + i386-Linux|x86_64-Linux) > + ;; > + *) > + pie="no" > + ;; > + esac > +fi > + > +if test "$pie" != "no" ; then > + cat> $TMPC<< EOF > +int main(void) { return 0; } > +EOF > + if compile_prog "-fPIE -DPIE" "-pie"; then > + QEMU_CFLAGS="-fPIE -DPIE $QEMU_CFLAGS" > + LDFLAGS="-pie $LDFLAGS" > + pie="yes" > + if compile_prog "" "-Wl,-z,relro -Wl,-z,now" ; then > + LDFLAGS="-Wl,-z,relro -Wl,-z,now $LDFLAGS" > + fi > + else > + if test "$pie" = "yes"; then > + echo "PIE not available due to missing toolchain support" > + exit 1 > + else > + echo "Disabling PIE due to missing toolchain support" > + pie="no" > + fi > + fi > +fi > + > # > # Solaris specific configure tool chain decisions > # > @@ -2765,7 +2806,7 @@ 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 +3266,6 @@ 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 +3684,6 @@ 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 +3807,6 @@ 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