Kernel inspects and sets sender id instead of userspace.

Modified ipc handling so that from now on the kernel inspects and sets
the sender id if the receiver is receiving from L4_ANYTHREAD. This posed
a security problem since the receiver could not trust the sender for
sender information.

include/l4/api/kip.h

@@ -95,4 +95,5 @@ struct kip {
 extern struct kip kip;
 #endif /* __KERNEL__ */
 
+
 #endif /* __KIP_H__ */

include/l4/glue/arm/utcb.h

@@ -8,6 +8,10 @@
 
 #define MR_TOTAL		6
 
+#define	MR_TAG		0
+#define MR_SENDER	1
+#define MR_UNUSED_START	2
+
 /* Compact utcb for now! 8-) */
 struct utcb {
 	u32 mr[MR_TOTAL];