diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index bf5c28e..337f89d 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -1091,15 +1091,6 @@
 
 status_t SurfaceFlinger::getLayerDebugInfo(std::vector<LayerDebugInfo>* outLayers) const
         NO_THREAD_SAFETY_ANALYSIS {
-    IPCThreadState* ipc = IPCThreadState::self();
-    const int pid = ipc->getCallingPid();
-    const int uid = ipc->getCallingUid();
-    if ((uid != AID_SHELL) &&
-            !PermissionCache::checkPermission(sDump, pid, uid)) {
-        ALOGE("Layer debug info permission denied for pid=%d, uid=%d", pid, uid);
-        return PERMISSION_DENIED;
-    }
-
     // Try to acquire a lock for 1s, fail gracefully
     const status_t err = mStateLock.timedLock(s2ns(1));
     const bool locked = (err == NO_ERROR);
@@ -3258,9 +3249,8 @@
     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)) {
+        !PermissionCache::checkPermission(sAccessSurfaceFlinger, pid, uid)) {
         return false;
     }
     return true;
@@ -4446,51 +4436,64 @@
 }
 
 status_t SurfaceFlinger::CheckTransactCodeCredentials(uint32_t code) {
-    switch (code) {
-        case CREATE_CONNECTION:
-        case CREATE_DISPLAY:
+#pragma clang diagnostic push
+#pragma clang diagnostic error "-Wswitch-enum"
+    switch (static_cast<ISurfaceComposerTag>(code)) {
+        // These methods should at minimum make sure that the client requested
+        // access to SF.
         case BOOT_FINISHED:
         case CLEAR_ANIMATION_FRAME_STATS:
-        case GET_ANIMATION_FRAME_STATS:
-        case SET_POWER_MODE:
-        case GET_HDR_CAPABILITIES:
+        case CREATE_CONNECTION:
+        case CREATE_DISPLAY:
+        case DESTROY_DISPLAY:
         case ENABLE_VSYNC_INJECTIONS:
+        case GET_ACTIVE_COLOR_MODE:
+        case GET_ANIMATION_FRAME_STATS:
+        case GET_HDR_CAPABILITIES:
+        case SET_ACTIVE_CONFIG:
+        case SET_ACTIVE_COLOR_MODE:
         case INJECT_VSYNC:
-        {
-            // codes that require permission check
+        case SET_POWER_MODE: {
             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;
-        }
-        /*
-         * Calling setTransactionState is safe, because you need to have been
-         * granted a reference to Client* and Handle* to do anything with it.
-         *
-         * Creating a scoped connection is safe, as per discussion in ISurfaceComposer.h
-         */
-        case SET_TRANSACTION_STATE:
-        case CREATE_SCOPED_CONNECTION:
-        {
             return OK;
         }
-        case CAPTURE_SCREEN:
-        {
-            // codes that require permission check
+        case GET_LAYER_DEBUG_INFO: {
             IPCThreadState* ipc = IPCThreadState::self();
             const int pid = ipc->getCallingPid();
             const int uid = ipc->getCallingUid();
-            if ((uid != AID_GRAPHICS) &&
-                    !PermissionCache::checkPermission(sReadFramebuffer, pid, uid)) {
-                ALOGE("Permission Denial: can't read framebuffer pid=%d, uid=%d", pid, uid);
+            if ((uid != AID_SHELL) && !PermissionCache::checkPermission(sDump, pid, uid)) {
+                ALOGE("Layer debug info permission denied for pid=%d, uid=%d", pid, uid);
                 return PERMISSION_DENIED;
             }
-            break;
+            return OK;
         }
-        case CAPTURE_LAYERS: {
+        // Used by apps to hook Choreographer to SurfaceFlinger.
+        case CREATE_DISPLAY_EVENT_CONNECTION:
+        // The following calls are currently used by clients that do not
+        // request necessary permissions. However, they do not expose any secret
+        // information, so it is OK to pass them.
+        case AUTHENTICATE_SURFACE:
+        case GET_ACTIVE_CONFIG:
+        case GET_BUILT_IN_DISPLAY:
+        case GET_DISPLAY_COLOR_MODES:
+        case GET_DISPLAY_CONFIGS:
+        case GET_DISPLAY_STATS:
+        case GET_SUPPORTED_FRAME_TIMESTAMPS:
+        // Calling setTransactionState is safe, because you need to have been
+        // granted a reference to Client* and Handle* to do anything with it.
+        case SET_TRANSACTION_STATE:
+        // Creating a scoped connection is safe, as per discussion in ISurfaceComposer.h
+        case CREATE_SCOPED_CONNECTION: {
+            return OK;
+        }
+        case CAPTURE_LAYERS:
+        case CAPTURE_SCREEN: {
+            // codes that require permission check
             IPCThreadState* ipc = IPCThreadState::self();
             const int pid = ipc->getCallingPid();
             const int uid = ipc->getCallingUid();
@@ -4499,15 +4502,37 @@
                 ALOGE("Permission Denial: can't read framebuffer pid=%d, uid=%d", pid, uid);
                 return PERMISSION_DENIED;
             }
-            break;
+            return OK;
+        }
+        // The following codes are deprecated and should never be allowed to access SF.
+        case CONNECT_DISPLAY_UNUSED:
+        case CREATE_GRAPHIC_BUFFER_ALLOC_UNUSED: {
+            ALOGE("Attempting to access SurfaceFlinger with unused code: %u", code);
+            return PERMISSION_DENIED;
         }
     }
-    return OK;
+
+    // These codes are used for the IBinder protocol to either interrogate the recipient
+    // side of the transaction for its canonical interface descriptor or to dump its state.
+    // We let them pass by default.
+    if (code == IBinder::INTERFACE_TRANSACTION || code == IBinder::DUMP_TRANSACTION ||
+        code == IBinder::PING_TRANSACTION || code == IBinder::SHELL_COMMAND_TRANSACTION ||
+        code == IBinder::SYSPROPS_TRANSACTION) {
+        return OK;
+    }
+    // Numbers from 1000 to 1029 are currently use for backdoors. The code
+    // in onTransact verifies that the user is root, and has access to use SF.
+    if (code >= 1000 && code <= 1029) {
+        ALOGV("Accessing SurfaceFlinger through backdoor code: %u", code);
+        return OK;
+    }
+    ALOGE("Permission Denial: SurfaceFlinger did not recognize request code: %u", code);
+    return PERMISSION_DENIED;
+#pragma clang diagnostic pop
 }
 
-status_t SurfaceFlinger::onTransact(
-    uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags)
-{
+status_t SurfaceFlinger::onTransact(uint32_t code, const Parcel& data, Parcel* reply,
+                                    uint32_t flags) {
     status_t credentialCheck = CheckTransactCodeCredentials(code);
     if (credentialCheck != OK) {
         return credentialCheck;
diff --git a/services/surfaceflinger/tests/Android.bp b/services/surfaceflinger/tests/Android.bp
index c511c5e..604aa7d 100644
--- a/services/surfaceflinger/tests/Android.bp
+++ b/services/surfaceflinger/tests/Android.bp
@@ -17,6 +17,7 @@
     defaults: ["surfaceflinger_defaults"],
     test_suites: ["device-tests"],
     srcs: [
+        "Credentials_test.cpp",
         "Stress_test.cpp",
         "SurfaceInterceptor_test.cpp",
         "Transaction_test.cpp",
diff --git a/services/surfaceflinger/tests/Credentials_test.cpp b/services/surfaceflinger/tests/Credentials_test.cpp
new file mode 100644
index 0000000..8e23eb8e
--- /dev/null
+++ b/services/surfaceflinger/tests/Credentials_test.cpp
@@ -0,0 +1,331 @@
+#include <algorithm>
+#include <functional>
+#include <limits>
+#include <ostream>
+
+#include <gtest/gtest.h>
+
+#include <gui/ISurfaceComposer.h>
+#include <gui/LayerDebugInfo.h>
+#include <gui/Surface.h>
+#include <gui/SurfaceComposerClient.h>
+
+#include <private/android_filesystem_config.h>
+#include <private/gui/ComposerService.h>
+
+#include <ui/DisplayInfo.h>
+#include <utils/String8.h>
+
+namespace android {
+
+using Transaction = SurfaceComposerClient::Transaction;
+
+namespace {
+const String8 DISPLAY_NAME("Credentials Display Test");
+const String8 SURFACE_NAME("Test Surface Name");
+const int32_t MIN_LAYER_Z = 0;
+const int32_t MAX_LAYER_Z = std::numeric_limits<int32_t>::max();
+const uint32_t ROTATION = 0;
+const float FRAME_SCALE = 1.0f;
+} // namespace
+
+/**
+ * This class tests the CheckCredentials method in SurfaceFlinger.
+ * Methods like EnableVsyncInjections and InjectVsync are not tested since they do not
+ * return anything meaningful.
+ */
+class CredentialsTest : public ::testing::Test {
+protected:
+    void SetUp() override {
+        // Start the tests as root.
+        seteuid(AID_ROOT);
+
+        ASSERT_NO_FATAL_FAILURE(initClient());
+    }
+
+    void TearDown() override {
+        mComposerClient->dispose();
+        mBGSurfaceControl.clear();
+        mComposerClient.clear();
+        // Finish the tests as root.
+        seteuid(AID_ROOT);
+    }
+
+    sp<IBinder> mDisplay;
+    sp<IBinder> mVirtualDisplay;
+    sp<SurfaceComposerClient> mComposerClient;
+    sp<SurfaceControl> mBGSurfaceControl;
+    sp<SurfaceControl> mVirtualSurfaceControl;
+
+    void initClient() {
+        mComposerClient = new SurfaceComposerClient;
+        ASSERT_EQ(NO_ERROR, mComposerClient->initCheck());
+    }
+
+    void setupBackgroundSurface() {
+        mDisplay = SurfaceComposerClient::getBuiltInDisplay(ISurfaceComposer::eDisplayIdMain);
+        DisplayInfo info;
+        SurfaceComposerClient::getDisplayInfo(mDisplay, &info);
+        const ssize_t displayWidth = info.w;
+        const ssize_t displayHeight = info.h;
+
+        // Background surface
+        mBGSurfaceControl =
+                mComposerClient->createSurface(SURFACE_NAME, displayWidth, displayHeight,
+                                               PIXEL_FORMAT_RGBA_8888, 0);
+        ASSERT_TRUE(mBGSurfaceControl != nullptr);
+        ASSERT_TRUE(mBGSurfaceControl->isValid());
+
+        Transaction t;
+        t.setDisplayLayerStack(mDisplay, 0);
+        ASSERT_EQ(NO_ERROR,
+                  t.setLayer(mBGSurfaceControl, INT_MAX - 3).show(mBGSurfaceControl).apply());
+    }
+
+    void setupVirtualDisplay() {
+        mVirtualDisplay = SurfaceComposerClient::createDisplay(DISPLAY_NAME, true);
+        const ssize_t displayWidth = 100;
+        const ssize_t displayHeight = 100;
+
+        // Background surface
+        mVirtualSurfaceControl =
+                mComposerClient->createSurface(SURFACE_NAME, displayWidth, displayHeight,
+                                               PIXEL_FORMAT_RGBA_8888, 0);
+        ASSERT_TRUE(mVirtualSurfaceControl != nullptr);
+        ASSERT_TRUE(mVirtualSurfaceControl->isValid());
+
+        Transaction t;
+        t.setDisplayLayerStack(mVirtualDisplay, 0);
+        ASSERT_EQ(NO_ERROR,
+                  t.setLayer(mVirtualSurfaceControl, INT_MAX - 3)
+                          .show(mVirtualSurfaceControl)
+                          .apply());
+    }
+
+    /**
+     * Sets UID to imitate Graphic's process.
+     */
+    void setGraphicsUID() {
+        seteuid(AID_ROOT);
+        seteuid(AID_GRAPHICS);
+    }
+
+    /**
+     * Sets UID to imitate System's process.
+     */
+    void setSystemUID() {
+        seteuid(AID_ROOT);
+        seteuid(AID_SYSTEM);
+    }
+
+    /**
+     * Sets UID to imitate a process that doesn't have any special privileges in
+     * our code.
+     */
+    void setBinUID() {
+        seteuid(AID_ROOT);
+        seteuid(AID_BIN);
+    }
+
+    /**
+     * Template function the check a condition for different types of users: root
+     * graphics, system, and non-supported user. Root, graphics, and system should
+     * always equal privilegedValue, and non-supported user should equal unprivilegedValue.
+     */
+    template <typename T>
+    void checkWithPrivileges(std::function<T()> condition, T privilegedValue, T unprivilegedValue) {
+        // Check with root.
+        seteuid(AID_ROOT);
+        ASSERT_EQ(privilegedValue, condition());
+
+        // Check as a Graphics user.
+        setGraphicsUID();
+        ASSERT_EQ(privilegedValue, condition());
+
+        // Check as a system user.
+        setSystemUID();
+        ASSERT_EQ(privilegedValue, condition());
+
+        // Check as a non-supported user.
+        setBinUID();
+        ASSERT_EQ(unprivilegedValue, condition());
+    }
+};
+
+TEST_F(CredentialsTest, ClientInitTest) {
+    // Root can init can init the client.
+    ASSERT_NO_FATAL_FAILURE(initClient());
+
+    // Graphics can init the client.
+    setGraphicsUID();
+    ASSERT_NO_FATAL_FAILURE(initClient());
+
+    // System can init the client.
+    setSystemUID();
+    ASSERT_NO_FATAL_FAILURE(initClient());
+
+    // No one else can init the client.
+    setBinUID();
+    mComposerClient = new SurfaceComposerClient;
+    ASSERT_EQ(NO_INIT, mComposerClient->initCheck());
+}
+
+TEST_F(CredentialsTest, GetBuiltInDisplayAccessTest) {
+    std::function<bool()> condition = [=]() {
+        sp<IBinder> display(
+                SurfaceComposerClient::getBuiltInDisplay(ISurfaceComposer::eDisplayIdMain));
+        return (display != nullptr);
+    };
+    // Anyone can access display information.
+    ASSERT_NO_FATAL_FAILURE(checkWithPrivileges(condition, true, true));
+}
+
+TEST_F(CredentialsTest, AllowedGetterMethodsTest) {
+    // The following methods are tested with a UID that is not root, graphics,
+    // or system, to show that anyone can access them.
+    setBinUID();
+    sp<IBinder> display(SurfaceComposerClient::getBuiltInDisplay(ISurfaceComposer::eDisplayIdMain));
+    ASSERT_TRUE(display != nullptr);
+
+    DisplayInfo info;
+    ASSERT_EQ(NO_ERROR, SurfaceComposerClient::getDisplayInfo(display, &info));
+
+    Vector<DisplayInfo> configs;
+    ASSERT_EQ(NO_ERROR, SurfaceComposerClient::getDisplayConfigs(display, &configs));
+
+    ASSERT_EQ(NO_ERROR, SurfaceComposerClient::getActiveConfig(display));
+
+    ASSERT_NE(static_cast<ui::ColorMode>(BAD_VALUE),
+              SurfaceComposerClient::getActiveColorMode(display));
+}
+
+TEST_F(CredentialsTest, GetDisplayColorModesTest) {
+    sp<IBinder> display(SurfaceComposerClient::getBuiltInDisplay(ISurfaceComposer::eDisplayIdMain));
+    std::function<status_t()> condition = [=]() {
+        Vector<ui::ColorMode> outColorModes;
+        return SurfaceComposerClient::getDisplayColorModes(display, &outColorModes);
+    };
+    ASSERT_NO_FATAL_FAILURE(checkWithPrivileges<status_t>(condition, NO_ERROR, NO_ERROR));
+}
+
+TEST_F(CredentialsTest, SetActiveConfigTest) {
+    sp<IBinder> display(SurfaceComposerClient::getBuiltInDisplay(ISurfaceComposer::eDisplayIdMain));
+    std::function<status_t()> condition = [=]() {
+        return SurfaceComposerClient::setActiveConfig(display, 0);
+    };
+    ASSERT_NO_FATAL_FAILURE(checkWithPrivileges<status_t>(condition, NO_ERROR, PERMISSION_DENIED));
+}
+
+TEST_F(CredentialsTest, SetActiveColorModeTest) {
+    sp<IBinder> display(SurfaceComposerClient::getBuiltInDisplay(ISurfaceComposer::eDisplayIdMain));
+    std::function<status_t()> condition = [=]() {
+        return SurfaceComposerClient::setActiveColorMode(display, ui::ColorMode::NATIVE);
+    };
+    ASSERT_NO_FATAL_FAILURE(checkWithPrivileges<status_t>(condition, NO_ERROR, PERMISSION_DENIED));
+}
+
+TEST_F(CredentialsTest, CreateSurfaceTest) {
+    sp<IBinder> display(SurfaceComposerClient::getBuiltInDisplay(ISurfaceComposer::eDisplayIdMain));
+    DisplayInfo info;
+    SurfaceComposerClient::getDisplayInfo(display, &info);
+    const ssize_t displayWidth = info.w;
+    const ssize_t displayHeight = info.h;
+
+    std::function<bool()> condition = [=]() {
+        mBGSurfaceControl =
+                mComposerClient->createSurface(SURFACE_NAME, displayWidth, displayHeight,
+                                               PIXEL_FORMAT_RGBA_8888, 0);
+        return mBGSurfaceControl != nullptr && mBGSurfaceControl->isValid();
+    };
+    ASSERT_NO_FATAL_FAILURE(checkWithPrivileges(condition, true, false));
+}
+
+TEST_F(CredentialsTest, CreateDisplayTest) {
+    std::function<bool()> condition = [=]() {
+        sp<IBinder> testDisplay = SurfaceComposerClient::createDisplay(DISPLAY_NAME, true);
+        return testDisplay.get() != nullptr;
+    };
+    ASSERT_NO_FATAL_FAILURE(checkWithPrivileges(condition, true, false));
+
+    condition = [=]() {
+        sp<IBinder> testDisplay = SurfaceComposerClient::createDisplay(DISPLAY_NAME, false);
+        return testDisplay.get() != nullptr;
+    };
+    ASSERT_NO_FATAL_FAILURE(checkWithPrivileges(condition, true, false));
+}
+
+TEST_F(CredentialsTest, DISABLED_DestroyDisplayTest) {
+    setupVirtualDisplay();
+
+    DisplayInfo info;
+    ASSERT_EQ(NO_ERROR, SurfaceComposerClient::getDisplayInfo(mVirtualDisplay, &info));
+    SurfaceComposerClient::destroyDisplay(mVirtualDisplay);
+    // This test currently fails. TODO(b/112002626): Find a way to properly create
+    // a display in the test environment, so that destroy display can remove it.
+    ASSERT_EQ(NAME_NOT_FOUND, SurfaceComposerClient::getDisplayInfo(mVirtualDisplay, &info));
+}
+
+TEST_F(CredentialsTest, CaptureTest) {
+    sp<IBinder> display(SurfaceComposerClient::getBuiltInDisplay(ISurfaceComposer::eDisplayIdMain));
+    std::function<status_t()> condition = [=]() {
+        sp<GraphicBuffer> outBuffer;
+        return ScreenshotClient::capture(display, Rect(), 0 /*reqWidth*/, 0 /*reqHeight*/,
+                                         MIN_LAYER_Z, MAX_LAYER_Z, false, ROTATION, &outBuffer);
+    };
+    ASSERT_NO_FATAL_FAILURE(checkWithPrivileges<status_t>(condition, NO_ERROR, PERMISSION_DENIED));
+}
+
+TEST_F(CredentialsTest, CaptureLayersTest) {
+    setupBackgroundSurface();
+    sp<GraphicBuffer> outBuffer;
+    std::function<status_t()> condition = [=]() {
+        sp<GraphicBuffer> outBuffer;
+        return ScreenshotClient::captureLayers(mBGSurfaceControl->getHandle(), Rect(), FRAME_SCALE,
+                                               &outBuffer);
+    };
+    ASSERT_NO_FATAL_FAILURE(checkWithPrivileges<status_t>(condition, NO_ERROR, PERMISSION_DENIED));
+}
+
+/**
+ * The following tests are for methods accessible directly through SurfaceFlinger.
+ */
+
+/**
+ * An app can pass a buffer queue to the media server and ask the media server to decode a DRM video
+ * to that buffer queue. The media server is the buffer producer in this case. Because the app may create
+ * its own buffer queue and act as the buffer consumer, the media server wants to be careful to avoid
+ * sending decoded video frames to the app. This is where authenticateSurfaceTexture call comes in, to check
+ * the consumer of a buffer queue is SurfaceFlinger.
+ */
+TEST_F(CredentialsTest, AuthenticateSurfaceTextureTest) {
+    setupBackgroundSurface();
+    sp<IGraphicBufferProducer> producer =
+            mBGSurfaceControl->getSurface()->getIGraphicBufferProducer();
+    sp<ISurfaceComposer> sf(ComposerService::getComposerService());
+
+    std::function<bool()> condition = [=]() { return sf->authenticateSurfaceTexture(producer); };
+    // Anyone should be able to check if the consumer of the buffer queue is SF.
+    ASSERT_NO_FATAL_FAILURE(checkWithPrivileges(condition, true, true));
+}
+
+TEST_F(CredentialsTest, GetLayerDebugInfo) {
+    setupBackgroundSurface();
+    sp<ISurfaceComposer> sf(ComposerService::getComposerService());
+
+    // Historically, only root and shell can access the getLayerDebugInfo which
+    // is called when we call dumpsys. I don't see a reason why we should change this.
+    std::vector<LayerDebugInfo> outLayers;
+    // Check with root.
+    seteuid(AID_ROOT);
+    ASSERT_EQ(NO_ERROR, sf->getLayerDebugInfo(&outLayers));
+
+    // Check as a shell.
+    seteuid(AID_SHELL);
+    ASSERT_EQ(NO_ERROR, sf->getLayerDebugInfo(&outLayers));
+
+    // Check as anyone else.
+    seteuid(AID_ROOT);
+    seteuid(AID_BIN);
+    ASSERT_EQ(PERMISSION_DENIED, sf->getLayerDebugInfo(&outLayers));
+}
+} // namespace android
diff --git a/services/surfaceflinger/tests/SurfaceFlinger_test.filter b/services/surfaceflinger/tests/SurfaceFlinger_test.filter
index 731e628..1319e12 100644
--- a/services/surfaceflinger/tests/SurfaceFlinger_test.filter
+++ b/services/surfaceflinger/tests/SurfaceFlinger_test.filter
@@ -1,5 +1,5 @@
 {
         "presubmit": {
-            "filter": "LayerTransactionTest.*:LayerUpdateTest.*:ChildLayerTest.*:SurfaceFlingerStress.*:CropLatchingTest.*:GeometryLatchingTest.*:ScreenCaptureTest.*:DereferenceSurfaceControlTest.*:SurfaceInterceptorTest.*:-CropLatchingTest.FinalCropLatchingBufferOldSize"
+            "filter": "CredentialsTest.*:LayerTransactionTest.*:LayerUpdateTest.*:ChildLayerTest.*:SurfaceFlingerStress.*:CropLatchingTest.*:GeometryLatchingTest.*:ScreenCaptureTest.*:DereferenceSurfaceControlTest.*:SurfaceInterceptorTest.*:-CropLatchingTest.FinalCropLatchingBufferOldSize"
         }
 }