From 59836e143c55c56a413630fe86846a22268e0f6a Mon Sep 17 00:00:00 2001
From: Enginex0 <enginex0@users.noreply.github.com>
Date: Tue, 19 May 2026 13:05:36 +0100
Subject: [PATCH] feat(intercept): inject SSE on non-AEAD updateAad

Real MediaTek mt6768 KeyMint silently returns OK on non-AEAD
updateAad, contradicting AOSP's mandate at
system/keymint/ta/src/operation.rs:430-446 to throw InvalidTag
when aad_allowed is false. Duck-detector flags this divergence
as "updateAad mismatch" in OperationErrorPathProbe.

Wire UPDATE_AAD into OperationInterceptor and inject
ServiceSpecificException(INVALID_TAG) when create params
indicate non-AEAD. AEAD (BlockMode.GCM) passes through to real
KeyMint untouched so AES-GCM round-trips remain valid.
---
 .../keystore/shim/KeyMintSecurityLevelInterceptor.kt      | 3 ++-
 .../interception/keystore/shim/OperationInterceptor.kt    | 8 +++++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/app/src/main/java/org/matrix/TEESimulator/interception/keystore/shim/KeyMintSecurityLevelInterceptor.kt b/app/src/main/java/org/matrix/TEESimulator/interception/keystore/shim/KeyMintSecurityLevelInterceptor.kt
index 8e57f01..6a9ea1c 100644
--- a/app/src/main/java/org/matrix/TEESimulator/interception/keystore/shim/KeyMintSecurityLevelInterceptor.kt
+++ b/app/src/main/java/org/matrix/TEESimulator/interception/keystore/shim/KeyMintSecurityLevelInterceptor.kt
@@ -194,7 +194,8 @@ class KeyMintSecurityLevelInterceptor(
                     SystemLogger.info("Found new IKeystoreOperation. Registering interceptor...")
                     val backdoor = getBackdoor(target)
                     if (backdoor != null) {
-                        val interceptor = OperationInterceptor(operation, backdoor)
+                        val isAead = parsedParams.blockMode.firstOrNull() == BlockMode.GCM
+                        val interceptor = OperationInterceptor(operation, backdoor, isAead)
                         register(backdoor, operationBinder, interceptor, OperationInterceptor.INTERCEPTED_CODES)
                         interceptedOperations[operationBinder] = interceptor
                     } else {
diff --git a/app/src/main/java/org/matrix/TEESimulator/interception/keystore/shim/OperationInterceptor.kt b/app/src/main/java/org/matrix/TEESimulator/interception/keystore/shim/OperationInterceptor.kt
index c8236a3..b8051ac 100644
--- a/app/src/main/java/org/matrix/TEESimulator/interception/keystore/shim/OperationInterceptor.kt
+++ b/app/src/main/java/org/matrix/TEESimulator/interception/keystore/shim/OperationInterceptor.kt
@@ -13,6 +13,7 @@ import org.matrix.TEESimulator.interception.keystore.InterceptorUtils
 class OperationInterceptor(
     private val original: IKeystoreOperation,
     private val backdoor: IBinder,
+    private val isAead: Boolean,
 ) : BinderInterceptor() {
 
     override fun onPreTransact(
@@ -27,6 +28,10 @@ class OperationInterceptor(
         val methodName = transactionNames[code] ?: "unknown code=$code"
         logTransaction(txId, methodName, callingUid, callingPid, true)
 
+        if (code == UPDATE_AAD_TRANSACTION && !isAead) {
+            return InterceptorUtils.createServiceSpecificErrorReply(KeystoreErrorCodes.invalidTag)
+        }
+
         if (code == FINISH_TRANSACTION || code == ABORT_TRANSACTION) {
             KeyMintSecurityLevelInterceptor.removeOperationInterceptor(target, backdoor)
         }
@@ -44,7 +49,8 @@ class OperationInterceptor(
         private val ABORT_TRANSACTION =
             InterceptorUtils.getTransactCode(IKeystoreOperation.Stub::class.java, "abort")
 
-        val INTERCEPTED_CODES = intArrayOf(FINISH_TRANSACTION, ABORT_TRANSACTION)
+        val INTERCEPTED_CODES =
+            intArrayOf(UPDATE_AAD_TRANSACTION, FINISH_TRANSACTION, ABORT_TRANSACTION)
 
         private val transactionNames: Map<Int, String> by lazy {
             IKeystoreOperation.Stub::class