From 36362544fb039599c0eb58d839e90ffb5410ad27 Mon Sep 17 00:00:00 2001 From: Marek Polacek Date: Wed, 9 Feb 2022 15:18:43 -0500 Subject: [PATCH] configure: Implement --enable-host-bind-now As promised in the --enable-host-pie patch, this patch adds another configure option, --enable-host-bind-now, which adds -z now when linking the compiler executables in order to extend hardening. BIND_NOW with RELRO allows the GOT to be marked RO; this prevents GOT modification attacks. This option does not affect linking of target libraries; you can use LDFLAGS_FOR_TARGET=-Wl,-z,relro,-z,now to enable RELRO/BIND_NOW. Bootstrapped/regtested on x86_64-pc-linux-gnu (with the option enabled vs not enabled). I suppose this is GCC 13 material, but maybe I'll get some comments anyway. c++tools/ChangeLog: * configure.ac (--enable-host-bind-now): New check. * configure: Regenerate. gcc/ChangeLog: * configure.ac (--enable-host-bind-now): New check. Add -Wl,-z,now to LD_PICFLAG if --enable-host-bind-now. * configure: Regenerate. * doc/install.texi: Document --enable-host-bind-now. lto-plugin/ChangeLog: * configure.ac (--enable-host-bind-now): New check. Link with -z,now. * configure: Regenerate. --- c++tools/configure | 11 +++++++++++ c++tools/configure.ac | 7 +++++++ gcc/configure | 20 ++++++++++++++++++-- gcc/configure.ac | 13 ++++++++++++- gcc/doc/install.texi | 6 ++++++ lto-plugin/configure | 20 ++++++++++++++++++-- lto-plugin/configure.ac | 11 +++++++++++ 7 files changed, 83 insertions(+), 5 deletions(-) diff --git a/c++tools/configure b/c++tools/configure index c1aceb8404a..25432b5040d 100755 --- a/c++tools/configure +++ b/c++tools/configure @@ -631,6 +631,7 @@ ac_ct_CC GREP CXXCPP LD_PICFLAG +enable_host_bind_now PICFLAG MAINTAINER CXX_AUX_TOOLS @@ -704,6 +705,7 @@ enable_c___tools enable_checking enable_default_pie enable_host_pie +enable_host_bind_now with_gcc_major_version_only ' ac_precious_vars='build_alias @@ -1336,6 +1338,7 @@ Optional Features: yes,no,all,none,release. --enable-default-pie enable Position Independent Executable as default --enable-host-pie build host code as PIE + --enable-host-bind-now link host code as BIND_NOW Optional Packages: --with-PACKAGE[=ARG] use PACKAGE [ARG=yes] @@ -3009,6 +3012,14 @@ fi +# Enable --enable-host-bind-now +# Check whether --enable-host-bind-now was given. +if test "${enable_host_bind_now+set}" = set; then : + enableval=$enable_host_bind_now; LD_PICFLAG="$LD_PICFLAG -Wl,-z,now" +fi + + + # Check if O_CLOEXEC is defined by fcntl diff --git a/c++tools/configure.ac b/c++tools/configure.ac index 1e42689f2eb..d3f23f66f00 100644 --- a/c++tools/configure.ac +++ b/c++tools/configure.ac @@ -110,6 +110,13 @@ AC_ARG_ENABLE(host-pie, [build host code as PIE])], [PICFLAG=-fPIE; LD_PICFLAG=-pie], []) AC_SUBST(PICFLAG) + +# Enable --enable-host-bind-now +AC_ARG_ENABLE(host-bind-now, +[AS_HELP_STRING([--enable-host-bind-now], + [link host code as BIND_NOW])], +[LD_PICFLAG="$LD_PICFLAG -Wl,-z,now"], []) +AC_SUBST(enable_host_bind_now) AC_SUBST(LD_PICFLAG) # Check if O_CLOEXEC is defined by fcntl diff --git a/gcc/configure b/gcc/configure index 2ded5d4c50b..5671dc7dcf4 100755 --- a/gcc/configure +++ b/gcc/configure @@ -635,6 +635,7 @@ CET_HOST_FLAGS LD_PICFLAG PICFLAG enable_default_pie +enable_host_bind_now enable_host_pie enable_host_shared enable_plugin @@ -1023,6 +1024,7 @@ enable_version_specific_runtime_libs enable_plugin enable_host_shared enable_host_pie +enable_host_bind_now enable_libquadmath_support with_linker_hash_style with_diagnostics_color @@ -1786,6 +1788,7 @@ Optional Features: --enable-plugin enable plugin support --enable-host-shared build host code as shared libraries --enable-host-pie build host code as PIE + --enable-host-bind-now link host code as BIND_NOW --disable-libquadmath-support disable libquadmath support for Fortran --enable-default-pie enable Position Independent Executable as default @@ -32109,6 +32112,14 @@ fi +# Enable --enable-host-bind-now +# Check whether --enable-host-bind-now was given. +if test "${enable_host_bind_now+set}" = set; then : + enableval=$enable_host_bind_now; +fi + + + # Check whether --enable-libquadmath-support was given. if test "${enable_libquadmath_support+set}" = set; then : enableval=$enable_libquadmath_support; ENABLE_LIBQUADMATH_SUPPORT=$enableval @@ -32295,6 +32306,8 @@ else PICFLAG= fi + + if test x$enable_host_pie = xyes; then LD_PICFLAG=-pie elif test x$gcc_cv_no_pie = xyes; then @@ -32303,6 +32316,9 @@ else LD_PICFLAG= fi +if test x$enable_host_bind_now = xyes; then + LD_PICFLAG="$LD_PICFLAG -Wl,-z,now" +fi diff --git a/gcc/configure.ac b/gcc/configure.ac index dca995aeec7..6017bcbc8c6 100644 --- a/gcc/configure.ac +++ b/gcc/configure.ac @@ -7497,6 +7497,12 @@ AC_ARG_ENABLE(host-pie, [build host code as PIE])]) AC_SUBST(enable_host_pie) +# Enable --enable-host-bind-now +AC_ARG_ENABLE(host-bind-now, +[AS_HELP_STRING([--enable-host-bind-now], + [link host code as BIND_NOW])]) +AC_SUBST(enable_host_bind_now) + AC_ARG_ENABLE(libquadmath-support, [AS_HELP_STRING([--disable-libquadmath-support], [disable libquadmath support for Fortran])], @@ -7638,6 +7644,8 @@ else PICFLAG= fi +AC_SUBST([PICFLAG]) + if test x$enable_host_pie = xyes; then LD_PICFLAG=-pie elif test x$gcc_cv_no_pie = xyes; then @@ -7646,7 +7654,10 @@ else LD_PICFLAG= fi -AC_SUBST([PICFLAG]) +if test x$enable_host_bind_now = xyes; then + LD_PICFLAG="$LD_PICFLAG -Wl,-z,now" +fi + AC_SUBST([LD_PICFLAG]) # Enable Intel CET on Intel CET enabled host if jit is enabled. diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi index 9747f832a75..b59af198d3e 100644 --- a/gcc/doc/install.texi +++ b/gcc/doc/install.texi @@ -1041,6 +1041,12 @@ protection against Return Oriented Programming (ROP) attacks. in which case @option{-fPIC} is used when compiling, and @option{-pie} when linking. +@item --enable-host-bind-now +Specify that the @emph{host} executables should be linked with the option +@option{-Wl,-z,now}, which means that the dynamic linker will resolve all +symbols when the executables are started, and that in turn allows RELRO to +mark the GOT read-only, resulting in better security. + @item @anchor{with-gnu-as}--with-gnu-as Specify that the compiler should assume that the assembler it finds is the GNU assembler. However, this does not modify diff --git a/lto-plugin/configure b/lto-plugin/configure index baa84adbb6c..669ccaede52 100755 --- a/lto-plugin/configure +++ b/lto-plugin/configure @@ -656,6 +656,7 @@ accel_dir_suffix gcc_build_dir CET_HOST_FLAGS ac_lto_plugin_ldflags +enable_host_bind_now ac_lto_plugin_warn_cflags EGREP GREP @@ -771,6 +772,7 @@ enable_maintainer_mode with_libiberty enable_dependency_tracking enable_largefile +enable_host_bind_now enable_cet with_gcc_major_version_only enable_shared @@ -1418,6 +1420,7 @@ Optional Features: --disable-dependency-tracking speeds up one-time build --disable-largefile omit support for large files + --enable-host-bind-now link host code as BIND_NOW --enable-cet enable Intel CET in host libraries [default=auto] --enable-shared[=PKGS] build shared libraries [default=yes] --enable-static[=PKGS] build static libraries [default=yes] @@ -5662,6 +5665,19 @@ if test "x$have_static_libgcc" = xyes; then ac_lto_plugin_ldflags="-Wc,-static-libgcc" fi +# Enable --enable-host-bind-now +# Check whether --enable-host-bind-now was given. +if test "${enable_host_bind_now+set}" = set; then : + enableval=$enable_host_bind_now; +fi + + + +if test x$enable_host_bind_now = xyes; then + ac_lto_plugin_ldflags="$ac_lto_plugin_ldflags -Wl,-z,now" +fi + + # Check whether --enable-cet was given. if test "${enable_cet+set}" = set; then : diff --git a/lto-plugin/configure.ac b/lto-plugin/configure.ac index 7e6f729e9dc..5d5fea8fe70 100644 --- a/lto-plugin/configure.ac +++ b/lto-plugin/configure.ac @@ -25,6 +25,17 @@ LDFLAGS="$saved_LDFLAGS" if test "x$have_static_libgcc" = xyes; then ac_lto_plugin_ldflags="-Wc,-static-libgcc" fi + +# Enable --enable-host-bind-now +AC_ARG_ENABLE(host-bind-now, +[AS_HELP_STRING([--enable-host-bind-now], + [link host code as BIND_NOW])]) +AC_SUBST(enable_host_bind_now) + +if test x$enable_host_bind_now = xyes; then + ac_lto_plugin_ldflags="$ac_lto_plugin_ldflags -Wl,-z,now" +fi + AC_SUBST(ac_lto_plugin_ldflags) GCC_CET_HOST_FLAGS(CET_HOST_FLAGS) base-commit: bf799d3409cb9a189114a6c9ff5b7cd123915764 -- 2.34.1