commit 6bb12824db3c540775b2b737331ed3f448a50e2e
author Sally Qi <sallyqi@google.com> Wed Oct 05 11:42:30 2022 -0700
committer Alec Mouri <alecmouri@google.com> Wed Dec 07 20:07:42 2022 +0000
tree 80fe473715979ca49138c3666479db15586700d1
parent a84abc85435e3b3519e77cbebf396bf3e2d14d6e

Add security check to getPhysicalDisplayToken binder function.

- There is a possible way to take over the screen display and swap the
  display content due to a missing permission check.
- Add a short-term fix for WCG checking failure because of new
  permission check added to SF::getPhysicalDisplayToken: change two
  function signatures (getStaticDisplayInfo and getDynamicDisplayInfo).
- To make short-term fix workable, split getDynamicDisplayInfo binder
  call into two, one is to take display id, one is to take display token
  as old codes show to avoid huge modification on other callees.

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

services/surfaceflinger/SurfaceFlinger.h

diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 6ddcfbc..e265939 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -512,10 +512,13 @@
     status_t getDisplayStats(const sp<IBinder>& displayToken, DisplayStatInfo* stats);
     status_t getDisplayState(const sp<IBinder>& displayToken, ui::DisplayState*)
             EXCLUDES(mStateLock);
-    status_t getStaticDisplayInfo(const sp<IBinder>& displayToken, ui::StaticDisplayInfo*)
+    status_t getStaticDisplayInfo(int64_t displayId, ui::StaticDisplayInfo*) EXCLUDES(mStateLock);
+    status_t getDynamicDisplayInfoFromId(int64_t displayId, ui::DynamicDisplayInfo*)
             EXCLUDES(mStateLock);
-    status_t getDynamicDisplayInfo(const sp<IBinder>& displayToken, ui::DynamicDisplayInfo*)
-            EXCLUDES(mStateLock);
+    status_t getDynamicDisplayInfoFromToken(const sp<IBinder>& displayToken,
+                                            ui::DynamicDisplayInfo*) EXCLUDES(mStateLock);
+    void getDynamicDisplayInfoInternal(ui::DynamicDisplayInfo*&, const sp<DisplayDevice>&,
+                                       const display::DisplaySnapshot&);
     status_t getDisplayNativePrimaries(const sp<IBinder>& displayToken, ui::DisplayPrimaries&);
     status_t setActiveColorMode(const sp<IBinder>& displayToken, ui::ColorMode colorMode);
     status_t getBootDisplayModeSupport(bool* outSupport) const;
@@ -702,7 +705,7 @@
      */
     bool applyTransactionState(const FrameTimelineInfo& info,
                                std::vector<ResolvedComposerState>& state,
-                               const Vector<DisplayState>& displays, uint32_t flags,
+                               Vector<DisplayState>& displays, uint32_t flags,
                                const InputWindowCommands& inputWindowCommands,
                                const int64_t desiredPresentTime, bool isAutoTimestamp,
                                const client_cache_t& uncacheBuffer, const int64_t postTime,
@@ -1401,10 +1404,12 @@
                                    gui::DisplayStatInfo* outStatInfo) override;
     binder::Status getDisplayState(const sp<IBinder>& display,
                                    gui::DisplayState* outState) override;
-    binder::Status getStaticDisplayInfo(const sp<IBinder>& display,
+    binder::Status getStaticDisplayInfo(int64_t displayId,
                                         gui::StaticDisplayInfo* outInfo) override;
-    binder::Status getDynamicDisplayInfo(const sp<IBinder>& display,
-                                         gui::DynamicDisplayInfo* outInfo) override;
+    binder::Status getDynamicDisplayInfoFromId(int64_t displayId,
+                                               gui::DynamicDisplayInfo* outInfo) override;
+    binder::Status getDynamicDisplayInfoFromToken(const sp<IBinder>& display,
+                                                  gui::DynamicDisplayInfo* outInfo) override;
     binder::Status getDisplayNativePrimaries(const sp<IBinder>& display,
                                              gui::DisplayPrimaries* outPrimaries) override;
     binder::Status setActiveColorMode(const sp<IBinder>& display, int colorMode) override;
@@ -1489,6 +1494,8 @@
     status_t checkAccessPermission(bool usePermissionCache = kUsePermissionCache);
     status_t checkControlDisplayBrightnessPermission();
     status_t checkReadFrameBufferPermission();
+    static void getDynamicDisplayInfoInternal(ui::DynamicDisplayInfo& info,
+                                              gui::DynamicDisplayInfo*& outInfo);
 
 private:
     sp<SurfaceFlinger> mFlinger;