Bind Android ChildProcessServices to a specific client PID.

content/public/android/java/src/org/chromium/content/app/ChildProcessServiceImpl.java

Index: content/public/android/java/src/org/chromium/content/app/ChildProcessServiceImpl.java
diff --git a/content/public/android/java/src/org/chromium/content/app/ChildProcessServiceImpl.java b/content/public/android/java/src/org/chromium/content/app/ChildProcessServiceImpl.java
index fde50c8f4b2427b5b341b8026ae88bbb11505a8f..0c02ad8aa4c20fc8fd5ba0fa598b8977c9cadbba 100644
--- a/content/public/android/java/src/org/chromium/content/app/ChildProcessServiceImpl.java
+++ b/content/public/android/java/src/org/chromium/content/app/ChildProcessServiceImpl.java
@@ -67,6 +67,8 @@ public class ChildProcessServiceImpl {
     private ChromiumLinkerParams mLinkerParams;
     // Child library process type.
     private int mLibraryProcessType;
+    // PID of the client of this service, set in bindToCaller().
+    private int mBoundCallingPid;
 
     private static AtomicReference<Context> sContext = new AtomicReference<>(null);
     private boolean mLibraryInitialized;
@@ -97,7 +99,27 @@ public class ChildProcessServiceImpl {
     private final IChildProcessService.Stub mBinder = new IChildProcessService.Stub() {
         // NOTE: Implement any IChildProcessService methods here.
         @Override
+        public boolean bindToCaller() {
+            int callingPid = Binder.getCallingPid();
+            if (mBoundCallingPid == 0) {
+                mBoundCallingPid = callingPid;
+            } else if (mBoundCallingPid != callingPid) {
+                Log.e(TAG, "This service is already bound by pid %d, cannot bind for pid %d",
+                        mBoundCallingPid, callingPid);
+                return false;
+            }
+            return true;
+        }
+
+        @Override
         public int setupConnection(Bundle args, IChildProcessCallback callback) {
+            int callingPid = Binder.getCallingPid();
+            if (mBoundCallingPid != callingPid) {
+                Log.e(TAG, "Client pid %d does not match the bound pid %d", callingPid,

[Tobias Sargeant, 2017/01/14 23:24:57]

Maybe log a different message if mBoundCallingPid is zero, so that it's clear
that bindToCaller wasn't called?

Do accesses to mBoundCallingPid need a lock?

[Torne, 2017/01/16 12:44:43]

Yeah, this isn't threadsafe right now I think (there's more than one binder
thread). It either needs a lock, or to be an atomic we can test-and-set.

[Robert Sesek, 2017/01/17 19:51:22]

Done.

[Robert Sesek, 2017/01/17 19:51:22]

Added a lock. Also mCallback was already not-thread-safe, so protected that too.

+                        mBoundCallingPid);
+                return -1;
+            }
+
             mCallback = callback;
             getServiceInfo(args);
             return Process.myPid();