gcc/gcc11-bind-now.patch

From 36362544fb039599c0eb58d839e90ffb5410ad27 Mon Sep 17 00:00:00 2001
From: Marek Polacek <polacek@redhat.com>
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