Enable stack protection by default for gcc versions that support it.

2008-09-05 18:46:08 +00:00
parent 36164fa8fa
commit cff22138ac
2 changed files with 101 additions and 0 deletions
@@ -30,6 +30,8 @@ AC_ISC_POSIX
 AC_HEADER_STDC
 AC_C_BIGENDIAN

+GCC_STACK_PROTECTOR
+
 # Check taken from glib
 AC_MSG_CHECKING(for the suffix of shared libraries)
 case "$host_os" in
@@ -0,0 +1,99 @@
+dnl
+dnl Useful macros for autoconf to check for ssp-patched gcc
+dnl 1.0 - September 2003 - Tiago Sousa <mirage@kaotik.org>
+dnl 1.1 - August 2006 - Ted Percival <ted@midg3t.net>
+dnl     * Stricter language checking (C or C++)
+dnl     * Adds GCC_STACK_PROTECT_LIB to add -lssp to LDFLAGS as necessary
+dnl     * Caches all results
+dnl     * Uses macros to ensure correct ouput in quiet/silent mode
+dnl 1.2 - April 2007 - Ted Percival <ted@midg3t.net>
+dnl     * Added GCC_STACK_PROTECTOR macro for simpler (one-line) invocation
+dnl     * GCC_STACK_PROTECT_LIB now adds -lssp to LIBS rather than LDFLAGS
+dnl
+dnl About ssp:
+dnl GCC extension for protecting applications from stack-smashing attacks
+dnl http://www.research.ibm.com/trl/projects/security/ssp/
+dnl
+dnl Usage:
+dnl Most people will simply call GCC_STACK_PROTECTOR.
+dnl If you only use one of C or C++, you can save time by only calling the
+dnl macro appropriate for that language. In that case you should also call
+dnl GCC_STACK_PROTECT_LIB first.
+dnl
+dnl GCC_STACK_PROTECTOR
+dnl Tries to turn on stack protection for C and C++ by calling the following
+dnl three macros with the right languages.
+dnl
+dnl GCC_STACK_PROTECT_CC
+dnl checks -fstack-protector with the C compiler, if it exists then updates
+dnl CFLAGS and defines ENABLE_SSP_CC
+dnl
+dnl GCC_STACK_PROTECT_CXX
+dnl checks -fstack-protector with the C++ compiler, if it exists then updates
+dnl CXXFLAGS and defines ENABLE_SSP_CXX
+dnl
+dnl GCC_STACK_PROTECT_LIB
+dnl adds -lssp to LIBS if it is available
+dnl ssp is usually provided as part of libc, but was previously a separate lib
+dnl It does not hurt to add -lssp even if libc provides SSP - in that case
+dnl libssp will simply be ignored.
+dnl
+
+AC_DEFUN([GCC_STACK_PROTECT_LIB],[
+  AC_CACHE_CHECK([whether libssp exists], ssp_cv_lib,
+    [ssp_old_libs="$LIBS"
+     LIBS="$LIBS -lssp"
+     AC_TRY_LINK(,, ssp_cv_lib=yes, ssp_cv_lib=no)
+     LIBS="$ssp_old_libs"
+    ])
+  if test $ssp_cv_lib = yes; then
+    LIBS="$LIBS -lssp"
+  fi
+])
+
+AC_DEFUN([GCC_STACK_PROTECT_CC],[
+  AC_LANG_ASSERT(C)
+  if test "X$CC" != "X"; then
+    AC_CACHE_CHECK([whether ${CC} accepts -fstack-protector],
+      ssp_cv_cc,
+      [ssp_old_cflags="$CFLAGS"
+       CFLAGS="$CFLAGS -fstack-protector"
+       AC_TRY_COMPILE(,, ssp_cv_cc=yes, ssp_cv_cc=no)
+       CFLAGS="$ssp_old_cflags"
+      ])
+    if test $ssp_cv_cc = yes; then
+      CFLAGS="$CFLAGS -fstack-protector"
+      AC_DEFINE([ENABLE_SSP_CC], 1, [Define if SSP C support is enabled.])
+    fi
+  fi
+])
+
+AC_DEFUN([GCC_STACK_PROTECT_CXX],[
+  AC_LANG_ASSERT(C++)
+  if test "X$CXX" != "X"; then
+    AC_CACHE_CHECK([whether ${CXX} accepts -fstack-protector],
+      ssp_cv_cxx,
+      [ssp_old_cxxflags="$CXXFLAGS"
+       CXXFLAGS="$CXXFLAGS -fstack-protector"
+       AC_TRY_COMPILE(,, ssp_cv_cxx=yes, ssp_cv_cxx=no)
+       CXXFLAGS="$ssp_old_cxxflags"
+      ])
+    if test $ssp_cv_cxx = yes; then
+      CXXFLAGS="$CXXFLAGS -fstack-protector"
+      AC_DEFINE([ENABLE_SSP_CXX], 1, [Define if SSP C++ support is enabled.])
+    fi
+  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++])
+])
+