dnl * Adds GCC_STACK_PROTECT_LIB to add -lssp to LDFLAGS as necessary
dnl * Caches all results
dnl * Uses macros to ensure correct ouput in quiet/silent mode
+dnl 1.2 - April 2007 - Ted Percival <ted@midg3t.net>
+dnl * Added GCC_STACK_PROTECTOR macro for simpler (one-line) invocation
+dnl * GCC_STACK_PROTECT_LIB now adds -lssp to LIBS rather than LDFLAGS
dnl
dnl About ssp:
dnl GCC extension for protecting applications from stack-smashing attacks
dnl http://www.research.ibm.com/trl/projects/security/ssp/
dnl
dnl Usage:
-dnl Call GCC_STACK_PROTECT_LIB to determine if the library implementing SSP is
-dnl available, then the appropriate C or C++ language's test. If you are using
-dnl both C and C++ you will need to use AC_LANG_PUSH and AC_LANG_POP to ensure
-dnl the right language is being used for each test.
+dnl Most people will simply call GCC_STACK_PROTECTOR.
+dnl If you only use one of C or C++, you can save time by only calling the
+dnl macro appropriate for that language. In that case you should also call
+dnl GCC_STACK_PROTECT_LIB first.
dnl
-dnl GCC_STACK_PROTECT_LIB
-dnl adds libssp to the LDFLAGS if it is available
+dnl GCC_STACK_PROTECTOR
+dnl Tries to turn on stack protection for C and C++ by calling the following
+dnl three macros with the right languages.
dnl
dnl GCC_STACK_PROTECT_CC
dnl checks -fstack-protector with the C compiler, if it exists then updates
dnl checks -fstack-protector with the C++ compiler, if it exists then updates
dnl CXXFLAGS and defines ENABLE_SSP_CXX
dnl
+dnl GCC_STACK_PROTECT_LIB
+dnl adds -lssp to LIBS if it is available
+dnl ssp is usually provided as part of libc, but was previously a separate lib
+dnl It does not hurt to add -lssp even if libc provides SSP - in that case
+dnl libssp will simply be ignored.
+dnl
AC_DEFUN([GCC_STACK_PROTECT_LIB],[
AC_CACHE_CHECK([whether libssp exists], ssp_cv_lib,
- [ssp_old_ldflags="$LDFLAGS"
- LDFLAGS="$LDFLAGS -lssp"
+ [ssp_old_libs="$LIBS"
+ LIBS="$LIBS -lssp"
AC_TRY_LINK(,, ssp_cv_lib=yes, ssp_cv_lib=no)
- LDFLAGS="$ssp_old_ldflags"
+ LIBS="$ssp_old_libs"
])
if test $ssp_cv_lib = yes; then
- LDFLAGS="$LDFLAGS -lssp"
+ LIBS="$LIBS -lssp"
fi
])
AC_CACHE_CHECK([whether ${CC} accepts -fstack-protector],
ssp_cv_cc,
[ssp_old_cflags="$CFLAGS"
- CFLAGS="$CFLAGS -fstack-protector"
+ CFLAGS="$CFLAGS -fstack-protector -Werror"
AC_TRY_COMPILE(,, ssp_cv_cc=yes, ssp_cv_cc=no)
CFLAGS="$ssp_old_cflags"
])
AC_CACHE_CHECK([whether ${CXX} accepts -fstack-protector],
ssp_cv_cxx,
[ssp_old_cxxflags="$CXXFLAGS"
- CXXFLAGS="$CXXFLAGS -fstack-protector"
+ CXXFLAGS="$CXXFLAGS -fstack-protector -Werror"
AC_TRY_COMPILE(,, ssp_cv_cxx=yes, ssp_cv_cxx=no)
CXXFLAGS="$ssp_old_cxxflags"
])
fi
])
+AC_DEFUN([GCC_STACK_PROTECTOR],[
+ GCC_STACK_PROTECT_LIB
+
+ AC_LANG_PUSH([C])
+ GCC_STACK_PROTECT_CC
+ AC_LANG_POP([C])
+
+ AC_LANG_PUSH([C++])
+ GCC_STACK_PROTECT_CXX
+ AC_LANG_POP([C++])
+])
+