DO NOT MERGE: Context#startInstrumentation could be started from SHELL only now.

Or, if an instrumentation starts another instrumentation and so on,
and the original instrumentation is started from SHELL, allow all
Context#startInstrumentation calls in this chain.

Otherwise, it'll throw a SecurityException.

Bug: 237766679
Test: atest CtsAppTestCases:InstrumentationTest
Merged-In: Ia08f225c21a3933067d066a578ea4af9c23e7d4c
Merged-In: I1b76f61c5fd6c9f7e738978592260945a606f40c
Merged-In: I3ea7aa27bd776fec546908a37f667f680da9c892
Change-Id: I7ca7345b064e8e74f7037b8fa3ed45bb6423e406

services/core/java/com/android/server/am/ActivityManagerService.java

@@ -16927,6 +16927,17 @@ public class ActivityManagerService extends IActivityManager.Stub
                 reportStartInstrumentationFailureLocked(watcher, className, msg);
                 throw new SecurityException(msg);
             }
+            if (!Build.IS_DEBUGGABLE && callingUid != ROOT_UID && callingUid != SHELL_UID
+                    && callingUid != SYSTEM_UID && !hasActiveInstrumentationLocked(callingPid)) {
+                // If it's not debug build and not called from root/shell/system uid, reject it.
+                final String msg = "Permission Denial: instrumentation test "
+                        + className + " from pid=" + callingPid + ", uid=" + callingUid
+                        + ", pkgName=" + getPackageNameByPid(callingPid)
+                        + " not allowed because it's not started from SHELL";
+                Slog.wtfQuiet(TAG, msg);
+                reportStartInstrumentationFailureLocked(watcher, className, msg);
+                throw new SecurityException(msg);
+            }
 
             ActiveInstrumentation activeInstr = new ActiveInstrumentation(this);
             activeInstr.mClass = className;
@@ -16995,6 +17006,29 @@ public class ActivityManagerService extends IActivityManager.Stub
         return true;
     }
 
+    @GuardedBy("this")
+    private boolean hasActiveInstrumentationLocked(int pid) {
+        if (pid == 0) {
+            return false;
+        }
+        synchronized (mPidsSelfLocked) {
+            ProcessRecord process = mPidsSelfLocked.get(pid);
+            return process != null && process.getActiveInstrumentation() != null;
+        }
+    }
+
+    private String getPackageNameByPid(int pid) {
+        synchronized (mPidsSelfLocked) {
+            final ProcessRecord app = mPidsSelfLocked.get(pid);
+
+            if (app != null && app.info != null) {
+                return app.info.packageName;
+            }
+
+            return null;
+        }
+    }
+
     private boolean isCallerShell() {
         final int callingUid = Binder.getCallingUid();
         return callingUid == SHELL_UID || callingUid == ROOT_UID;