cameraserver: Enforce system only camera permissions in camera1 api.

In camera1 api
- getNumberOfCameras won't count hidden secure cameras.
- getNumberOfCameras will return public non system cameras or public
  cameras depending on whether the client has SYSTEM_CAMERA and CAMERA
  permissions or not.
- getCameraInfo checks for SYSTEM_CAMERA and CAMERA permissions in case
  the info is requested for a system camera.

Bug: 140243224

Test: Harcode all cameras as SYSTEM_ONLY_CAMERA; cts camera1 tests
      get 0 on calling getNumberOfCameras() without using
      adoptShellPermissionIdentity().

Test: Harcode all cameras as SYSTEM_ONLY_CAMERA; cts camera1 tests
      get a finite number on calling getNumberOfCameras() when
      adoptShellPermissionIdentity() is used.

Test: Harcode all cameras as HIDDEN_CAMERA; cts camera1 tests
      get 0 when calling getNumberOfCameras.

Change-Id: I9d1721fd5e94fa7f692c3da52aa667ae9247d368
Signed-off-by: Jayant Chowdhary <jchowdhary@google.com>
diff --git a/services/camera/libcameraservice/CameraService.cpp b/services/camera/libcameraservice/CameraService.cpp
index a503838..b662a4d 100644
--- a/services/camera/libcameraservice/CameraService.cpp
+++ b/services/camera/libcameraservice/CameraService.cpp
@@ -135,6 +135,7 @@
 CameraService::CameraService() :
         mEventLog(DEFAULT_EVENT_LOG_LENGTH),
         mNumberOfCameras(0),
+        mNumberOfCamerasWithoutSystemCamera(0),
         mSoundRef(0), mInitialized(false),
         mAudioRestriction(hardware::camera2::ICameraDeviceUser::AUDIO_RESTRICTION_NONE) {
     ALOGI("CameraService started (pid=%d)", getpid());
@@ -260,11 +261,32 @@
     enumerateProviders();
 }
 
+void CameraService::filterAPI1SystemCameraLocked(
+        const std::vector<std::string> &normalDeviceIds) {
+    mNormalDeviceIdsWithoutSystemCamera.clear();
+    for (auto &deviceId : normalDeviceIds) {
+        if (getSystemCameraKind(String8(deviceId.c_str())) ==
+                SystemCameraKind::SYSTEM_ONLY_CAMERA) {
+            // All system camera ids will necessarily come after public camera
+            // device ids as per the HAL interface contract.
+            break;
+        }
+        mNormalDeviceIdsWithoutSystemCamera.push_back(deviceId);
+    }
+    ALOGV("%s: number of API1 compatible public cameras is %zu", __FUNCTION__,
+              mNormalDeviceIdsWithoutSystemCamera.size());
+}
+
 void CameraService::updateCameraNumAndIds() {
     Mutex::Autolock l(mServiceLock);
-    mNumberOfCameras = mCameraProviderManager->getCameraCount();
+    std::pair<int, int> systemAndNonSystemCameras = mCameraProviderManager->getCameraCount();
+    // Excludes hidden secure cameras
+    mNumberOfCameras =
+            systemAndNonSystemCameras.first + systemAndNonSystemCameras.second;
+    mNumberOfCamerasWithoutSystemCamera = systemAndNonSystemCameras.second;
     mNormalDeviceIds =
             mCameraProviderManager->getAPI1CompatibleCameraDeviceIds();
+    filterAPI1SystemCameraLocked(mNormalDeviceIds);
 }
 
 void CameraService::addStates(const String8 id) {
@@ -446,15 +468,31 @@
     broadcastTorchModeStatus(cameraId, newStatus);
 }
 
+static bool hasPermissionsForSystemCamera(int callingPid, int callingUid) {
+    return checkPermission(sSystemCameraPermission, callingPid, callingUid) &&
+            checkPermission(sCameraPermission, callingPid, callingUid);
+}
+
 Status CameraService::getNumberOfCameras(int32_t type, int32_t* numCameras) {
     ATRACE_CALL();
     Mutex::Autolock l(mServiceLock);
+    bool hasSystemCameraPermissions =
+            hasPermissionsForSystemCamera(CameraThreadState::getCallingPid(),
+                    CameraThreadState::getCallingUid());
     switch (type) {
         case CAMERA_TYPE_BACKWARD_COMPATIBLE:
-            *numCameras = static_cast<int>(mNormalDeviceIds.size());
+            if (hasSystemCameraPermissions) {
+                *numCameras = static_cast<int>(mNormalDeviceIds.size());
+            } else {
+                *numCameras = static_cast<int>(mNormalDeviceIdsWithoutSystemCamera.size());
+            }
             break;
         case CAMERA_TYPE_ALL:
-            *numCameras = mNumberOfCameras;
+            if (hasSystemCameraPermissions) {
+                *numCameras = mNumberOfCameras;
+            } else {
+                *numCameras = mNumberOfCamerasWithoutSystemCamera;
+            }
             break;
         default:
             ALOGW("%s: Unknown camera type %d",
@@ -469,20 +507,31 @@
         CameraInfo* cameraInfo) {
     ATRACE_CALL();
     Mutex::Autolock l(mServiceLock);
+    std::string cameraIdStr = cameraIdIntToStrLocked(cameraId);
+    if (shouldRejectSystemCameraConnection(String8(cameraIdStr.c_str()))) {
+        return STATUS_ERROR_FMT(ERROR_INVALID_OPERATION, "Unable to retrieve camera"
+                "characteristics for system only device %s: ", cameraIdStr.c_str());
+    }
 
     if (!mInitialized) {
         return STATUS_ERROR(ERROR_DISCONNECTED,
                 "Camera subsystem is not available");
     }
-
-    if (cameraId < 0 || cameraId >= mNumberOfCameras) {
+    bool hasSystemCameraPermissions =
+            hasPermissionsForSystemCamera(CameraThreadState::getCallingPid(),
+                    CameraThreadState::getCallingUid());
+    int cameraIdBound = mNumberOfCamerasWithoutSystemCamera;
+    if (hasSystemCameraPermissions) {
+        cameraIdBound = mNumberOfCameras;
+    }
+    if (cameraId < 0 || cameraId >= cameraIdBound) {
         return STATUS_ERROR(ERROR_ILLEGAL_ARGUMENT,
                 "CameraId is not valid");
     }
 
     Status ret = Status::ok();
     status_t err = mCameraProviderManager->getCameraInfo(
-            cameraIdIntToStrLocked(cameraId), cameraInfo);
+            cameraIdStr.c_str(), cameraInfo);
     if (err != OK) {
         ret = STATUS_ERROR_FMT(ERROR_INVALID_OPERATION,
                 "Error retrieving camera info from device %d: %s (%d)", cameraId,
@@ -493,13 +542,20 @@
 }
 
 std::string CameraService::cameraIdIntToStrLocked(int cameraIdInt) {
-    if (cameraIdInt < 0 || cameraIdInt >= static_cast<int>(mNormalDeviceIds.size())) {
+    const std::vector<std::string> *deviceIds = &mNormalDeviceIdsWithoutSystemCamera;
+    auto callingPid = CameraThreadState::getCallingPid();
+    auto callingUid = CameraThreadState::getCallingUid();
+    if (checkPermission(sSystemCameraPermission, callingPid, callingUid) ||
+            getpid() == callingPid) {
+        deviceIds = &mNormalDeviceIds;
+    }
+    if (cameraIdInt < 0 || cameraIdInt >= static_cast<int>(deviceIds->size())) {
         ALOGE("%s: input id %d invalid: valid range  (0, %zu)",
-                __FUNCTION__, cameraIdInt, mNormalDeviceIds.size());
+                __FUNCTION__, cameraIdInt, deviceIds->size());
         return std::string{};
     }
 
-    return mNormalDeviceIds[cameraIdInt];
+    return (*deviceIds)[cameraIdInt];
 }
 
 String8 CameraService::cameraIdIntToStr(int cameraIdInt) {
@@ -1348,11 +1404,6 @@
     return ret;
 }
 
-static bool hasPermissionsForSystemCamera(int callingPid, int callingUid) {
-    return checkPermission(sSystemCameraPermission, callingPid, callingUid) &&
-            checkPermission(sCameraPermission, callingPid, callingUid);
-}
-
 bool CameraService::shouldSkipStatusUpdates(const String8& cameraId, bool isVendorListener,
         int clientPid, int clientUid) const {
     SystemCameraKind systemCameraKind = getSystemCameraKind(cameraId);
@@ -3151,6 +3202,8 @@
     dprintf(fd, "\n== Service global info: ==\n\n");
     dprintf(fd, "Number of camera devices: %d\n", mNumberOfCameras);
     dprintf(fd, "Number of normal camera devices: %zu\n", mNormalDeviceIds.size());
+    dprintf(fd, "Number of public camera devices visible to API1: %zu\n",
+            mNormalDeviceIdsWithoutSystemCamera.size());
     for (size_t i = 0; i < mNormalDeviceIds.size(); i++) {
         dprintf(fd, "    Device %zu maps to \"%s\"\n", i, mNormalDeviceIds[i].c_str());
     }