getCallingSid: get calling security context

This call gets the security context of the calling process when
requested.

Bug: 121035042
Test: boot

Change-Id: Ia8a4c0cb4a9c86dcc0d3b7583014237f879a3074
Merged-In: Ia8a4c0cb4a9c86dcc0d3b7583014237f879a3074
diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp
index ca6a97d..9f8c408 100644
--- a/libs/binder/Parcel.cpp
+++ b/libs/binder/Parcel.cpp
@@ -215,7 +215,7 @@
     }
 
     if (binder != nullptr) {
-        IBinder *local = binder->localBinder();
+        BBinder *local = binder->localBinder();
         if (!local) {
             BpBinder *proxy = binder->remoteBinder();
             if (proxy == nullptr) {
@@ -227,6 +227,9 @@
             obj.handle = handle;
             obj.cookie = 0;
         } else {
+            if (local->isRequestingSid()) {
+                obj.flags |= FLAT_BINDER_FLAG_TXN_SECURITY_CTX;
+            }
             obj.hdr.type = BINDER_TYPE_BINDER;
             obj.binder = reinterpret_cast<uintptr_t>(local->getWeakRefs());
             obj.cookie = reinterpret_cast<uintptr_t>(local);