Merge "SurfaceFlinger: Fixes around rotation and cropping." into pi-dev

3 files changed, 55 insertions, 17 deletions

diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 2595ec1a05..6d5a598e89 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -345,20 +345,25 @@ FloatRect Layer::computeBounds(const Region& activeTransparentRegion) const {
         win.intersect(s.crop, &win);
     }
 
-    Rect bounds = win;
     const auto& p = mDrawingParent.promote();
+    FloatRect floatWin = win.toFloatRect();
+    FloatRect parentBounds = floatWin;
     if (p != nullptr) {
-        // Look in computeScreenBounds recursive call for explanation of
-        // why we pass false here.
-        bounds = p->computeScreenBounds(false /* reduceTransparentRegion */);
+        // We pass an empty Region here for reasons mirroring that of the case described in
+        // the computeScreenBounds reduceTransparentRegion=false case.
+        parentBounds = p->computeBounds(Region());
     }
 
-    Transform t = getTransform();
+    Transform t = s.active.transform;
 
-    FloatRect floatWin = win.toFloatRect();
-    if (p != nullptr) {
+
+    if (p != nullptr || !s.finalCrop.isEmpty()) {
         floatWin = t.transform(floatWin);
-        floatWin = floatWin.intersect(bounds.toFloatRect());
+        floatWin = floatWin.intersect(parentBounds);
+
+        if (!s.finalCrop.isEmpty()) {
+            floatWin = floatWin.intersect(s.finalCrop.toFloatRect());
+        }
         floatWin = t.inverse().transform(floatWin);
     }
 
@@ -1249,7 +1254,15 @@ bool Layer::setColor(const half3& color) {
     return true;
 }
 
-bool Layer::setMatrix(const layer_state_t::matrix22_t& matrix) {
+bool Layer::setMatrix(const layer_state_t::matrix22_t& matrix,
+        bool allowNonRectPreservingTransforms) {
+    Transform t;
+    t.set(matrix.dsdx, matrix.dtdy, matrix.dtdx, matrix.dsdy);
+
+    if (!allowNonRectPreservingTransforms && !t.preserveRects()) {
+        ALOGW("Attempt to set rotation matrix without permission ACCESS_SURFACE_FLINGER ignored");
+        return false;
+    }
     mCurrentState.sequence++;
     mCurrentState.requested.transform.set(matrix.dsdx, matrix.dtdy, matrix.dtdx, matrix.dsdy);
     mCurrentState.modified = true;
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 34811fb152..f4ae21aad5 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -258,7 +258,7 @@ public:
     // Set a 2x2 transformation matrix on the layer. This transform
     // will be applied after parent transforms, but before any final
     // producer specified transform.
-    bool setMatrix(const layer_state_t::matrix22_t& matrix);
+    bool setMatrix(const layer_state_t::matrix22_t& matrix, bool allowNonRectPreservingTransforms);
 
     // This second set of geometry attributes are controlled by
     // setGeometryAppliesWithResize, and their default mode is to be
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 66b41f5c76..787bbd2fcc 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -3342,6 +3342,18 @@ uint32_t SurfaceFlinger::setDisplayStateLocked(const DisplayState& s)
     return flags;
 }
 
+bool callingThreadHasUnscopedSurfaceFlingerAccess() {
+    IPCThreadState* ipc = IPCThreadState::self();
+    const int pid = ipc->getCallingPid();
+    const int uid = ipc->getCallingUid();
+
+    if ((uid != AID_GRAPHICS && uid != AID_SYSTEM) &&
+            !PermissionCache::checkPermission(sAccessSurfaceFlinger, pid, uid)) {
+        return false;
+    }
+    return true;
+}
+
 uint32_t SurfaceFlinger::setClientStateLocked(const ComposerState& composerState) {
     const layer_state_t& s = composerState.state;
     sp<Client> client(static_cast<Client*>(composerState.client.get()));
@@ -3423,7 +3435,22 @@ uint32_t SurfaceFlinger::setClientStateLocked(const ComposerState& composerState
             flags |= eTraversalNeeded;
     }
     if (what & layer_state_t::eMatrixChanged) {
-        if (layer->setMatrix(s.matrix))
+        // TODO: b/109894387
+        //
+        // SurfaceFlinger's renderer is not prepared to handle cropping in the face of arbitrary
+        // rotation. To see the problem observe that if we have a square parent, and a child
+        // of the same size, then we rotate the child 45 degrees around it's center, the child
+        // must now be cropped to a non rectangular 8 sided region.
+        //
+        // Of course we can fix this in the future. For now, we are lucky, SurfaceControl is
+        // private API, and the WindowManager only uses rotation in one case, which is on a top
+        // level layer in which cropping is not an issue.
+        //
+        // However given that abuse of rotation matrices could lead to surfaces extending outside
+        // of cropped areas, we need to prevent non-root clients without permission ACCESS_SURFACE_FLINGER
+        // (a.k.a. everyone except WindowManager and tests) from setting non rectangle preserving
+        // transformations.
+        if (layer->setMatrix(s.matrix, callingThreadHasUnscopedSurfaceFlingerAccess()))
             flags |= eTraversalNeeded;
     }
     if (what & layer_state_t::eTransparentRegionChanged) {
@@ -4440,12 +4467,10 @@ status_t SurfaceFlinger::CheckTransactCodeCredentials(uint32_t code) {
         case INJECT_VSYNC:
         {
             // codes that require permission check
-            IPCThreadState* ipc = IPCThreadState::self();
-            const int pid = ipc->getCallingPid();
-            const int uid = ipc->getCallingUid();
-            if ((uid != AID_GRAPHICS && uid != AID_SYSTEM) &&
-                    !PermissionCache::checkPermission(sAccessSurfaceFlinger, pid, uid)) {
-                ALOGE("Permission Denial: can't access SurfaceFlinger pid=%d, uid=%d", pid, uid);
+            if (!callingThreadHasUnscopedSurfaceFlingerAccess()) {
+                IPCThreadState* ipc = IPCThreadState::self();
+                ALOGE("Permission Denial: can't access SurfaceFlinger pid=%d, uid=%d",
+                        ipc->getCallingPid(), ipc->getCallingUid());
                 return PERMISSION_DENIED;
             }
             break;