commit 0e69ae88923133dca88f9818671e65957d9f244c Author: Jacob Appelbaum <jacob@appelbaum.net> Date: Mon Feb 13 17:43:01 2012 -0500 Add check for gcc and ld hardening flags. This adds a new one shot automake macro AX_ENABLE_HARDENING and it attempts to add the various security hardening flags we'd like to see if they're available. When they are not available, we simply skip adding the option. This should ensure that we have everything we could possibly have without adding incompatible flags or having to add a lot of weird cruft to the configure.ac file. --- configure.ac | 3 ++ m4/ax_build_hardening.m4 | 63 +++++++++++++++++++++++++++++++++++++ m4/ax_check_compile_flag.m4 | 72 +++++++++++++++++++++++++++++++++++++++++++ m4/ax_check_link_flag.m4 | 71 ++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 209 insertions(+), 0 deletions(-) diff --git a/configure.ac b/configure.ac index cf5bd43..34beb81 100644 --- a/configure.ac +++ b/configure.ac @@ -23,6 +23,9 @@ AC_CHECK_HEADERS([sys/socket.h]) AC_CHECK_HEADERS([sys/types.h]) AC_CHECK_HEADERS([netinet/in.h]) +### Compiler Hardening ### +AX_ENABLE_HARDENING + ### Libraries ### PKG_CHECK_MODULES([libevent], [libevent >= 2.0]) diff --git a/m4/ax_build_hardening.m4 b/m4/ax_build_hardening.m4 new file mode 100644 index 0000000..590a00d --- /dev/null +++ b/m4/ax_build_hardening.m4 @@ -0,0 +1,63 @@ + +# +# SYNOPSIS +# +# AX_ENABLE_HARDENING() +# +# DESCRIPTION +# +# Attempt to enable various gcc compile time and linker security hardening +# options. +# +# LICENSE +# +# Copyright (c) 2012 Jacob Appelbaum <jacob@appelbaum.net> +# +# This program is free software: you can redistribute it and/or modify it +# under the terms of the GNU General Public License as published by the +# Free Software Foundation, either version 3 of the License, or (at your +# option) any later version. +# +# This program is distributed in the hope that it will be useful, but +# WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General +# Public License for more details. +# +# You should have received a copy of the GNU General Public License along +# with this program. If not, see <http://www.gnu.org/licenses/>. +# +# As a special exception, the respective Autoconf Macro's copyright owner +# gives unlimited permission to copy, distribute and modify the configure +# scripts that are the output of Autoconf when processing the Macro. You +# need not follow the terms of the GNU General Public License when using +# or distributing such scripts, even though portions of the text of the +# Macro appear in them. The GNU General Public License (GPL) does govern +# all other use of the material that constitutes the Autoconf Macro. +# +# This special exception to the GPL applies to versions of the Autoconf +# Macro released by the Autoconf Archive. When you make and distribute a +# modified version of the Autoconf Macro, you may extend this special +# exception to the GPL to apply to your modified version as well. + +#serial 2 + +dnl This macro depends on AX_CHECK_COMPILE_FLAG and AX_CHECK_LINKER_FLAG +AC_DEFUN_ONCE([AX_ENABLE_HARDENING], [ + +### Compiler Hardening ### +# This requires ax_check_compile_flag.m4 +AX_CHECK_COMPILE_FLAG([-D_FORTIFY_SOURCE=2], [CFLAGS="$CFLAGS -D_FORTIFY_SOURCE=2"]) +AX_CHECK_COMPILE_FLAG([-fstack-protector-all], [CFLAGS="$CFLAGS -fstack-protector-all"]) +AX_CHECK_COMPILE_FLAG([-fwrapv], [CFLAGS="$CFLAGS -fwrapv"]) +AX_CHECK_COMPILE_FLAG([-fPIE], [CFLAGS="$CFLAGS -fPIE"]) +AX_CHECK_COMPILE_FLAG([--param ssp-buffer-size=1], [CFLAGS="$CFLAGS --param ssp-buffer-size=1"]) +AX_CHECK_COMPILE_FLAG([-fno-strict-aliasing], [CFLAGS="$CFLAGS -fno-strict-aliasing"]) +AX_CHECK_COMPILE_FLAG([-fno-strict-overflow], [CFLAGS="$CFLAGS -fno-strict-overflow"]) + +### Linker Hardening ### +# This requires ax_check_link_flag.m4 +AX_CHECK_LINK_FLAG([-pie], [LDFLAGS="$LDFLAGS -pie"]) +AX_CHECK_LINK_FLAG([-z relro], [LDFLAGS="$LDFLAGS -z relro"]) +AX_CHECK_LINK_FLAG([-z now], [LDFLAGS="$LDFLAGS -z now"]) + +]) diff --git a/m4/ax_check_compile_flag.m4 b/m4/ax_check_compile_flag.m4 new file mode 100644 index 0000000..c3a8d69 --- /dev/null +++ b/m4/ax_check_compile_flag.m4 @@ -0,0 +1,72 @@ +# =========================================================================== +# http://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html +# =========================================================================== +# +# SYNOPSIS +# +# AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS]) +# +# DESCRIPTION +# +# Check whether the given FLAG works with the current language's compiler +# or gives an error. (Warnings, however, are ignored) +# +# ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on +# success/failure. +# +# If EXTRA-FLAGS is defined, it is added to the current language's default +# flags (e.g. CFLAGS) when the check is done. The check is thus made with +# the flags: "CFLAGS EXTRA-FLAGS FLAG". This can for example be used to +# force the compiler to issue an error when a bad flag is given. +# +# NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this +# macro in sync with AX_CHECK_{PREPROC,LINK}_FLAG. +# +# LICENSE +# +# Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de> +# Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com> +# +# This program is free software: you can redistribute it and/or modify it +# under the terms of the GNU General Public License as published by the +# Free Software Foundation, either version 3 of the License, or (at your +# option) any later version. +# +# This program is distributed in the hope that it will be useful, but +# WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General +# Public License for more details. +# +# You should have received a copy of the GNU General Public License along +# with this program. If not, see <http://www.gnu.org/licenses/>. +# +# As a special exception, the respective Autoconf Macro's copyright owner +# gives unlimited permission to copy, distribute and modify the configure +# scripts that are the output of Autoconf when processing the Macro. You +# need not follow the terms of the GNU General Public License when using +# or distributing such scripts, even though portions of the text of the +# Macro appear in them. The GNU General Public License (GPL) does govern +# all other use of the material that constitutes the Autoconf Macro. +# +# This special exception to the GPL applies to versions of the Autoconf +# Macro released by the Autoconf Archive. When you make and distribute a +# modified version of the Autoconf Macro, you may extend this special +# exception to the GPL to apply to your modified version as well. + +#serial 2 + +AC_DEFUN([AX_CHECK_COMPILE_FLAG], +[AC_PREREQ(2.59)dnl for _AC_LANG_PREFIX +AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl +AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [ + ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS + _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1" + AC_COMPILE_IFELSE([AC_LANG_PROGRAM()], + [AS_VAR_SET(CACHEVAR,[yes])], + [AS_VAR_SET(CACHEVAR,[no])]) + _AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags]) +AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes], + [m4_default([$2], :)], + [m4_default([$3], :)]) +AS_VAR_POPDEF([CACHEVAR])dnl +])dnl AX_CHECK_COMPILE_FLAGS diff --git a/m4/ax_check_link_flag.m4 b/m4/ax_check_link_flag.m4 new file mode 100644 index 0000000..e2d0d36 --- /dev/null +++ b/m4/ax_check_link_flag.m4 @@ -0,0 +1,71 @@ +# =========================================================================== +# http://www.gnu.org/software/autoconf-archive/ax_check_link_flag.html +# =========================================================================== +# +# SYNOPSIS +# +# AX_CHECK_LINK_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS]) +# +# DESCRIPTION +# +# Check whether the given FLAG works with the linker or gives an error. +# (Warnings, however, are ignored) +# +# ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on +# success/failure. +# +# If EXTRA-FLAGS is defined, it is added to the linker's default flags +# when the check is done. The check is thus made with the flags: "LDFLAGS +# EXTRA-FLAGS FLAG". This can for example be used to force the linker to +# issue an error when a bad flag is given. +# +# NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this +# macro in sync with AX_CHECK_{PREPROC,COMPILE}_FLAG. +# +# LICENSE +# +# Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de> +# Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com> +# +# This program is free software: you can redistribute it and/or modify it +# under the terms of the GNU General Public License as published by the +# Free Software Foundation, either version 3 of the License, or (at your +# option) any later version. +# +# This program is distributed in the hope that it will be useful, but +# WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General +# Public License for more details. +# +# You should have received a copy of the GNU General Public License along +# with this program. If not, see <http://www.gnu.org/licenses/>. +# +# As a special exception, the respective Autoconf Macro's copyright owner +# gives unlimited permission to copy, distribute and modify the configure +# scripts that are the output of Autoconf when processing the Macro. You +# need not follow the terms of the GNU General Public License when using +# or distributing such scripts, even though portions of the text of the +# Macro appear in them. The GNU General Public License (GPL) does govern +# all other use of the material that constitutes the Autoconf Macro. +# +# This special exception to the GPL applies to versions of the Autoconf +# Macro released by the Autoconf Archive. When you make and distribute a +# modified version of the Autoconf Macro, you may extend this special +# exception to the GPL to apply to your modified version as well. + +#serial 2 + +AC_DEFUN([AX_CHECK_LINK_FLAG], +[AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_ldflags_$4_$1])dnl +AC_CACHE_CHECK([whether the linker accepts $1], CACHEVAR, [ + ax_check_save_flags=$LDFLAGS + LDFLAGS="$LDFLAGS $4 $1" + AC_LINK_IFELSE([AC_LANG_PROGRAM()], + [AS_VAR_SET(CACHEVAR,[yes])], + [AS_VAR_SET(CACHEVAR,[no])]) + LDFLAGS=$ax_check_save_flags]) +AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes], + [m4_default([$2], :)], + [m4_default([$3], :)]) +AS_VAR_POPDEF([CACHEVAR])dnl +])dnl AX_CHECK_LINK_FLAGS