Part 1 of 2 of security patch for KDM [CVE-2010-0436]

git-svn-id: svn://anonsvn.kde.org/home/kde/branches/trinity/kde-common/admin@1117040 283d02a7-25f6-0310-bc7c-ecb5cbfe19da

acinclude.m4.in

@@ -4741,6 +4741,61 @@ else
 fi
 ])
 
+AC_DEFUN([KDE_CHECK_HONORS_SOCKET_PERMS],
+[
+AC_MSG_CHECKING([if underlying system honors socket permissions])
+AC_CACHE_VAL(ac_cv_honors_socket_perms,
+[
+AC_LANG_SAVE
+AC_LANG_C
+ac_save_LIBS="$LIBS"
+ac_save_CPPFLAGS="$CPPFLAGS"
+LIBS="$all_libraries"
+CPPFLAGS="$CPPFLAGS $all_includes"
+AC_TRY_RUN(dnl
+[
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+int main()
+{
+    int fd, fd2;
+    struct sockaddr_un sa;
+
+    if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
+        return 2;
+    sa.sun_family = AF_UNIX;
+    strcpy(sa.sun_path, "testsock");
+    unlink(sa.sun_path);
+    if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)))
+        return 2;
+    chmod(sa.sun_path, 0);
+    setuid(getuid() + 1000);
+    if ((fd2 = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
+        return 2;
+    connect(fd2, (struct sockaddr *)&sa, sizeof(sa));
+    return errno != EACCES;
+}
+],
+            ac_cv_honors_socket_perms=yes,
+            ac_cv_honors_socket_perms=no,
+	    ac_cv_honors_socket_perms=no)
+LIBS="$ac_save_LIBS"
+CPPFLAGS="$ac_save_CPPFLAGS"
+AC_LANG_RESTORE
+])dnl
+if eval "test \"`echo $ac_cv_honors_socket_perms`\" = yes"; then
+  AC_MSG_RESULT(yes)
+  AC_DEFINE_UNQUOTED(HONORS_SOCKET_PERMS, 1, [Defined if the underlying system honors socket permissions])
+else
+  AC_MSG_RESULT(no)
+fi
+])
+
 AC_DEFUN([AM_DISABLE_LIBRARIES],
 [
     AC_PROVIDE([AM_ENABLE_STATIC])