some kernel don't have this. for post-1.4.2
#include <linux/keyctl.h>],
[#ifdef CONFIG_KEYS
request_key(NULL, NULL, NULL);
-#if !defined(KEY_POS_VIEW) || !defined(KEY_POS_SEARCH)
-#error "Your linux/key.h does not contain KEY_POS_VIEW or KEY_POS_SEARCH"
+#if !defined(KEY_POS_VIEW) || !defined(KEY_POS_SEARCH) || !defined(KEY_POS_SETATTR)
+#error "Your linux/key.h does not contain KEY_POS_VIEW or KEY_POS_SEARCH or KEY_POS_SETATTR"
#endif
#else
#error rebuild your kernel with CONFIG_KEYS