First Publicly Shared Version of ODKiTEE v15

serialization/api_support.c

@@ -0,0 +1,123 @@
+/*
+ * Copyright 2020 Google LLC. All Rights Reserved. This file and proprietary
+ * source code may only be used and distributed under the Widevine Master
+ * License Agreement.
+ */
+
+/*
+ * Support functions for the OEMCrypto API functions, related to
+ * message handling
+ */
+
+#include "OEMCryptoCENC.h"
+#include "api_support.h"
+#include "bump_allocator.h"
+#include "message.h"
+#include "shared_memory_allocator.h"
+#include "shared_memory_interface.h"
+#include "special_cases.h"
+#include "transport_interface.h"
+
+/*
+ * If true, the system has been invalidated due to a communications
+ * breakdown with the TEE.  This is a persistent condition and will
+ * cause OEMCrypto_ERROR_SYSTEM_INVALIDATED to be returned from any
+ * function that returns an OEMCryptoResult until the transport
+ * interface is reinitialized.
+*/
+static bool system_invalidated;
+
+/*
+ * This is the result code to be returned from any function that
+ * returns OEMCryptoResult code.
+ */
+OEMCryptoResult api_result;
+
+/*
+ * odkitee OEMCrypto API is single threaded
+ */
+pthread_mutex_t api_lock;
+
+/*
+ * Called at the beginning of every API function. Checks configuration
+ * state and if it is okay allocates a request message. Sets
+ * api_result based on the status of the operations, which will be
+ * returned from any API function that returns an OEMCryptoResult
+ * code. On exit, if api_result is not OEMCrypto_SUCCESS or NULL is
+ * returned, then any allocated messages will have been deallocated
+ * prior to returning.
+ */
+Message *API_InitializeRequest(void) {
+  api_result = OEMCrypto_SUCCESS;
+
+  SharedMemory_Reset();
+  BumpAllocator_Reset();
+  Message* request = ODK_Transport_AllocateMessage();
+  if (request == NULL) {
+    api_result = OEMCrypto_ERROR_INSUFFICIENT_RESOURCES;
+  } else if (GetStatus(request) != MESSAGE_STATUS_OK) {
+    /* The transport allocator must return initialized messages */
+    api_result = OEMCrypto_ERROR_SYSTEM_INVALIDATED;
+  }
+  if (api_result != OEMCrypto_SUCCESS) {
+    if (request != NULL) {
+      ODK_Transport_DeallocateMessage(request);
+      request = NULL;
+    }
+  }
+  return request;
+}
+
+/*
+ * Called to send the request message to the TEE and receive the
+ * response. Sets api_result based on the status of the
+ * operations. Returns either a valid response message or NULL. If
+ * NULL is returned or api_result != OEMCrypto_SUCCESS then any
+ * allocated messages will have been deallocated prior to returning.
+ */
+Message *API_Transact(Message* request) {
+  if (api_result != OEMCrypto_SUCCESS || request == NULL) {
+    return NULL;
+  }
+  ODK_Transport_Status transport_status = ODK_Transport_SendMessage(request);
+  Message* response = NULL;
+  if (transport_status == ODK_TRANSPORT_STATUS_IO_ERROR) {
+    api_result = OEMCrypto_ERROR_SYSTEM_INVALIDATED;
+  } else {
+    transport_status = ODK_Transport_ReceiveMessage(&response);
+    if (transport_status == ODK_TRANSPORT_STATUS_IO_ERROR || response == NULL) {
+      api_result = OEMCrypto_ERROR_SYSTEM_INVALIDATED;
+    } else if (GetStatus(response) != MESSAGE_STATUS_OK) {
+      api_result = OEMCrypto_ERROR_UNKNOWN_FAILURE;
+    }
+  }
+  if (api_result != OEMCrypto_SUCCESS) {
+    if (response) {
+      ODK_Transport_DeallocateMessage(response);
+      response = NULL;
+    }
+  }
+  return response;
+}
+
+/*
+ * Called at the end of every API function. Sets system_invalidated if
+ * the local api_result indicates a failure in the current
+ * function. Once system_invalidated is set, it will persist until
+ * reset by the next OEMCrypto_Inititalize/OEMCrypto_Terminate.
+ */
+OEMCryptoResult API_CheckResult(OEMCryptoResult unpacked_result) {
+  if (api_result == OEMCrypto_ERROR_SYSTEM_INVALIDATED) {
+    system_invalidated = true;
+  } else if (api_result == OEMCrypto_SUCCESS) {
+    api_result = unpacked_result;
+  }
+  return api_result;
+}
+
+/*
+ * Called by OEMCrypto_Terminate
+ */
+void API_Terminate(void) {
+  system_invalidated = false;
+}