Mitigate the security vulnerability by sanitizing the transaction flags.

- This is part of fix of commit
  Id9d9012d4ede9c8330f0ce1096bcb78e51b7c5df for backporting.
- Part of commit Id9d9012d4ede9c8330f0ce1096bcb78e51b7c5df which
  sanitizes the transaction flags from DisplayState instead.
- In rvc, we only have ACCESS_SURFACE_FLINGER permission check passed as
  `privileged` argument in SF::applyTransactionState. We can directly
  utilize it for sanitization in DiaplyState.
- In rvc code base, SF::setTransactionState pass a const array of
  displayState objects and then call SF::applyTransactionState. To
  successfully sanitize the flags for each displayState object, we
  convert this const array into non-const one before calling
  SF::applyTransactionState.

Bug: 248031255
Test: test using displaytoken app manually on the phone, test shell
screenrecord during using displaytoken; atest
android.hardware.camera2.cts.FastBasicsTest

Change-Id: Id9d9012d4ede9c8330f0ce1096bcb78e51b7c5df
Merged-In: Id9d9012d4ede9c8330f0ce1096bcb78e51b7c5df

4 files changed, 34 insertions, 7 deletions

diff --git a/libs/gui/LayerState.cpp b/libs/gui/LayerState.cpp
index dfcef8fe7a..a76a21c5c4 100644
--- a/libs/gui/LayerState.cpp
+++ b/libs/gui/LayerState.cpp
@@ -276,6 +276,27 @@ void DisplayState::merge(const DisplayState& other) {
     }
 }
 
+void DisplayState::sanitize(bool privileged) {
+    if (what & DisplayState::eLayerStackChanged) {
+        if (!privileged) {
+            what &= ~DisplayState::eLayerStackChanged;
+            ALOGE("Stripped attempt to set eLayerStackChanged in sanitize");
+        }
+    }
+    if (what & DisplayState::eDisplayProjectionChanged) {
+        if (!privileged) {
+            what &= ~DisplayState::eDisplayProjectionChanged;
+            ALOGE("Stripped attempt to set eDisplayProjectionChanged in sanitize");
+        }
+    }
+    if (what & DisplayState::eSurfaceChanged) {
+        if (!privileged) {
+            what &= ~DisplayState::eSurfaceChanged;
+            ALOGE("Stripped attempt to set eSurfaceChanged in sanitize");
+        }
+    }
+}
+
 void layer_state_t::merge(const layer_state_t& other) {
     if (other.what & ePositionChanged) {
         what |= ePositionChanged;
diff --git a/libs/gui/include/gui/LayerState.h b/libs/gui/include/gui/LayerState.h
index 39dbe9e035..b73bb89791 100644
--- a/libs/gui/include/gui/LayerState.h
+++ b/libs/gui/include/gui/LayerState.h
@@ -267,6 +267,7 @@ struct DisplayState {
 
     DisplayState();
     void merge(const DisplayState& other);
+    void sanitize(bool privileged);
 
     uint32_t what;
     sp<IBinder> token;
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 4165df9ae5..14da0c5daa 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -3273,7 +3273,7 @@ bool SurfaceFlinger::flushTransactionQueues() {
             auto& [applyToken, transactionQueue] = *it;
 
             while (!transactionQueue.empty()) {
-                const auto& transaction = transactionQueue.front();
+                auto& transaction = transactionQueue.front();
                 if (!transactionIsReadyToBeApplied(transaction.desiredPresentTime,
                                                    transaction.states)) {
                     setTransactionFlags(eTransactionFlushNeeded);
@@ -3372,13 +3372,18 @@ void SurfaceFlinger::setTransactionState(
         return;
     }
 
-    applyTransactionState(states, displays, flags, inputWindowCommands, desiredPresentTime,
+    Vector<DisplayState> displaysList;
+    for (auto& d : displays) {
+        displaysList.add(d);
+    }
+
+    applyTransactionState(states, displaysList, flags, inputWindowCommands, desiredPresentTime,
                           uncacheBuffer, postTime, privileged, hasListenerCallbacks,
                           listenerCallbacks);
 }
 
 void SurfaceFlinger::applyTransactionState(
-        const Vector<ComposerState>& states, const Vector<DisplayState>& displays, uint32_t flags,
+        const Vector<ComposerState>& states, Vector<DisplayState>& displays, uint32_t flags,
         const InputWindowCommands& inputWindowCommands, const int64_t desiredPresentTime,
         const client_cache_t& uncacheBuffer, const int64_t postTime, bool privileged,
         bool hasListenerCallbacks, const std::vector<ListenerCallbacks>& listenerCallbacks,
@@ -3401,7 +3406,8 @@ void SurfaceFlinger::applyTransactionState(
         }
     }
 
-    for (const DisplayState& display : displays) {
+    for (DisplayState& display : displays) {
+        display.sanitize(privileged);
         transactionFlags |= setDisplayStateLocked(display);
     }
 
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index ccaeb2d858..913158f386 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -618,9 +618,8 @@ private:
     /* ------------------------------------------------------------------------
      * Transactions
      */
-    void applyTransactionState(const Vector<ComposerState>& state,
-                               const Vector<DisplayState>& displays, uint32_t flags,
-                               const InputWindowCommands& inputWindowCommands,
+    void applyTransactionState(const Vector<ComposerState>& state, Vector<DisplayState>& displays,
+                               uint32_t flags, const InputWindowCommands& inputWindowCommands,
                                const int64_t desiredPresentTime,
                                const client_cache_t& uncacheBuffer, const int64_t postTime,
                                bool privileged, bool hasListenerCallbacks,