ODK: forward compatibility and nonce-free offline license support am: 8dc1d7a11d

Original change: https://googleplex-android-review.googlesource.com/c/platform/vendor/widevine/+/11688972

Change-Id: I61a70e52e875c017a706f1337d75405f19748dfa

libwvdrmengine/oemcrypto/odk/include/odk_structs.h

@@ -14,6 +14,12 @@
 #define ODK_MAJOR_VERSION 16
 #define ODK_MINOR_VERSION 2
 
+/* ODK Version string. Date changed automatically on each release. */
+#define ODK_RELEASE_DATE "ODK v16.2 2020-05-30"
+
+/* The  lowest version number for an ODK message. */
+#define ODK_FIRST_VERSION 16
+
 /* Some useful constants. */
 #define ODK_DEVICE_ID_LEN_MAX 64
 #define ODK_SHA256_HASH_SIZE 32

libwvdrmengine/oemcrypto/odk/src/core_message_deserialize.cpp

@@ -19,9 +19,6 @@ namespace oemcrypto_core_message {
 namespace deserialize {
 namespace {
 
-constexpr int EARLIEST_OEMCRYPTO_VERSION_WITH_ODK = 16;
-constexpr int LATEST_OEMCRYPTO_VERSION = 16;
-
 /**
  * Template for parsing requests
  *
@@ -59,21 +56,19 @@ bool ParseRequest(uint32_t message_type,
   core_request->session_id = core_message.nonce_values.session_id;
   // Verify that the minor version matches the released version for the given
   // major version.
-  if ((core_request->api_major_version < EARLIEST_OEMCRYPTO_VERSION_WITH_ODK) ||
+  if (core_request->api_major_version < ODK_FIRST_VERSION) {
-      (core_request->api_major_version > LATEST_OEMCRYPTO_VERSION)) {
+    // Non existing versions are not supported.
-    // Non existing and future versions are not supported.
     return false;
   } else if (core_request->api_major_version == 16) {
     // For version 16, we demand a minor version of at least 2.
+    // We accept 16.2, 16.3, or higher.
     if (core_request->api_major_version < 2) return false;
   } else {
     // Other versions do not (yet) have a restriction on minor number.
+    // In particular, future versions are accepted for forward compatibility.
   }
   return core_message.message_type == message_type &&
-         core_message.message_length == GetOffset(msg) &&
+         core_message.message_length == GetOffset(msg);
-         core_request->api_major_version >=
-             EARLIEST_OEMCRYPTO_VERSION_WITH_ODK &&
-         core_request->api_major_version <= LATEST_OEMCRYPTO_VERSION;
 }
 
 }  // namespace

libwvdrmengine/oemcrypto/odk/src/core_message_serialize.cpp

@@ -41,6 +41,12 @@ bool CreateResponse(uint32_t message_type, const S& core_request,
   header->nonce_values.api_minor_version = core_request.api_minor_version;
   header->nonce_values.nonce = core_request.nonce;
   header->nonce_values.session_id = core_request.session_id;
+  // The message API version for the response is the minimum of our version and
+  // the request's version.
+  if (core_request.api_major_version > ODK_MAJOR_VERSION) {
+    header->nonce_values.api_major_version = ODK_MAJOR_VERSION;
+    header->nonce_values.api_minor_version = ODK_MINOR_VERSION;
+  }
 
   static constexpr size_t BUF_CAPACITY = 2048;
   std::vector<uint8_t> buf(BUF_CAPACITY, 0);

libwvdrmengine/oemcrypto/odk/src/odk.c

@@ -190,9 +190,9 @@ OEMCryptoResult ODK_PrepareCoreRenewalRequest(uint8_t* message,
    * renewal. All releases use v15. */
   if (clock_values->timer_status == ODK_CLOCK_TIMER_STATUS_LICENSE_NOT_LOADED ||
       clock_values->timer_status == ODK_CLOCK_TIMER_STATUS_LICENSE_INACTIVE) {
-    nonce_values->api_major_version = 15;
+    nonce_values->api_major_version = ODK_FIRST_VERSION - 1;
   }
-  if (nonce_values->api_major_version < 16) {
+  if (nonce_values->api_major_version < ODK_FIRST_VERSION) {
     *core_message_size = 0;
     return OEMCrypto_SUCCESS;
   }
@@ -270,12 +270,28 @@ OEMCryptoResult ODK_ParseLicense(
     return err;
   }
 
-  /* This function should not be used for legacy licenses. */
+  /* We do not support future API version. Also, this function should not be
-  if (license_response.request.core_message.nonce_values.api_major_version !=
+   * used for legacy licenses. */
-      ODK_MAJOR_VERSION) {
+  if (license_response.request.core_message.nonce_values.api_major_version >
+          ODK_MAJOR_VERSION ||
+      license_response.request.core_message.nonce_values.api_major_version <
+          ODK_FIRST_VERSION) {
     return ODK_UNSUPPORTED_API;
   }
 
+  /* If the server sent us an older format, record the license's API version. */
+  if (nonce_values->api_major_version >
+      license_response.request.core_message.nonce_values.api_major_version) {
+    nonce_values->api_major_version =
+        license_response.request.core_message.nonce_values.api_major_version;
+    nonce_values->api_minor_version =
+        license_response.request.core_message.nonce_values.api_minor_version;
+  } else if (nonce_values->api_minor_version >
+             license_response.request.core_message.nonce_values
+                 .api_minor_version) {
+    nonce_values->api_minor_version =
+        license_response.request.core_message.nonce_values.api_minor_version;
+  }
   /* If the license has a provider session token (pst), then OEMCrypto should
    * have a usage entry loaded. The opposite is also an error.  */
   if ((usage_entry_present && parsed_license->pst.length == 0) ||
@@ -302,7 +318,7 @@ OEMCryptoResult ODK_ParseLicense(
    * OEMCrypto stores a hash of the core license request and only signs the
    * message body. Here, when we process the license response, we verify that
    * the server has the same hash of the core request.  */
-  if (initial_license_load &&
+  if (initial_license_load && parsed_license->nonce_required &&
       crypto_memcmp(request_hash, license_response.request_hash,
                     ODK_SHA256_HASH_SIZE)) {
     return ODK_ERROR_CORE_MESSAGE;