[DO NOT MERGE] Impose a threshold on the number of attributed op entries returned in a binder call am: 8e7990cecc

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/31593362

Change-Id: Ia45bcc644822f9692a50a0048e4ba82b204f1f1f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

1 files changed, 26 insertions, 2 deletions

diff --git a/services/core/java/com/android/server/appop/AppOpsService.java b/services/core/java/com/android/server/appop/AppOpsService.java
index 2e48b24eb25c..82b99fb8986d 100644
--- a/services/core/java/com/android/server/appop/AppOpsService.java
+++ b/services/core/java/com/android/server/appop/AppOpsService.java
@@ -231,6 +231,12 @@ public class AppOpsService extends IAppOpsService.Stub {
      *  {@link #upgradeLocked(int)} below. The first version was 1 */
     private static final int CURRENT_VERSION = 1;
 
+    /**
+     * The upper limit of total number of attributed op entries that can be returned in a binder
+     * transaction to avoid TransactionTooLargeException
+     */
+    private static final int NUM_ATTRIBUTED_OP_ENTRY_THRESHOLD = 2000;
+
     // Write at most every 30 minutes.
     static final long WRITE_DELAY = DEBUG ? 1000 : 30*60*1000;
 
@@ -2190,6 +2196,8 @@ public class AppOpsService extends IAppOpsService.Stub {
                 Manifest.permission.GET_APP_OPS_STATS,
                 Binder.getCallingPid(), Binder.getCallingUid())
                 == PackageManager.PERMISSION_GRANTED;
+        int totalAttributedOpEntryCount = 0;
+
         if (ops == null) {
             resOps = new ArrayList<>();
             for (int j = 0; j < pkgOps.size(); j++) {
@@ -2197,7 +2205,12 @@ public class AppOpsService extends IAppOpsService.Stub {
                 if (opRestrictsRead(curOp.op) && !shouldReturnRestrictedAppOps) {
                     continue;
                 }
-                resOps.add(getOpEntryForResult(curOp, elapsedNow));
+                if (totalAttributedOpEntryCount > NUM_ATTRIBUTED_OP_ENTRY_THRESHOLD) {
+                    break;
+                }
+                OpEntry opEntry = getOpEntryForResult(curOp, elapsedNow);
+                resOps.add(opEntry);
+                totalAttributedOpEntryCount += opEntry.getAttributedOpEntries().size();
             }
         } else {
             for (int j = 0; j < ops.length; j++) {
@@ -2209,10 +2222,21 @@ public class AppOpsService extends IAppOpsService.Stub {
                     if (resOps == null) {
                         resOps = new ArrayList<>();
                     }
-                    resOps.add(getOpEntryForResult(curOp, elapsedNow));
+                    if (totalAttributedOpEntryCount > NUM_ATTRIBUTED_OP_ENTRY_THRESHOLD) {
+                        break;
+                    }
+                    OpEntry opEntry = getOpEntryForResult(curOp, elapsedNow);
+                    resOps.add(opEntry);
+                    totalAttributedOpEntryCount += opEntry.getAttributedOpEntries().size();
                 }
             }
         }
+
+        if (totalAttributedOpEntryCount > NUM_ATTRIBUTED_OP_ENTRY_THRESHOLD) {
+            Slog.w(TAG, "The number of attributed op entries has exceeded the threshold. This "
+                    + "could be due to DoS attack from malicious apps. The result is throttled.");
+        }
+
         return resOps;
     }