common: return standard CEL event log instead of encoded ones (#117)

Author: Ruoyu-y

common/python/cctrusted_base/eventlog.py

@@ -40,9 +40,10 @@ class TcgEventLog:
     """
 
     TCG_FORMAT_PCCLIENT = 0
-    TCG_FORMAT_CEL_TLV = 1
-    TCG_FORMAT_CEL_JSON = 2
-    TCG_FORMAT_CEL_CBOR = 3
+    TCG_FORMAT_CEL = 1
+    TCG_FORMAT_CEL_TLV = 2
+    TCG_FORMAT_CEL_JSON = 3
+    TCG_FORMAT_CEL_CBOR = 4
 
     def __init__(self, rec_num:int, imr_index:int, event_type:TcgEventType, digests:list[TcgDigest],
                  event_size:int, event:bytes, extra_info=None) -> None:
@@ -59,9 +60,8 @@ def format_event_log(self, parse_format:str):
         if parse_format == self.TCG_FORMAT_PCCLIENT:
             return self._to_tcg_pcclient_format()
 
-        if parse_format in (self.TCG_FORMAT_CEL_JSON, self.TCG_FORMAT_CEL_CBOR,
-                            self.TCG_FORMAT_CEL_TLV) :
-            return self._to_tcg_canonical_format(parse_format)
+        if parse_format == self.TCG_FORMAT_CEL :
+            return self._to_tcg_canonical_format()
 
         return None
 
@@ -79,7 +79,7 @@ def _to_tcg_pcclient_format(self):
         return TcgImrEvent(self._imr_index, self._event_type, self._digests, self._event_size,
                                self._event)
 
-    def _to_tcg_canonical_format(self, encoding:str=None):
+    def _to_tcg_canonical_format(self):
         """The function to convert event log data into event log following
            Canonical Eventlog Spec.
         """
@@ -101,8 +101,9 @@ def _to_tcg_canonical_format(self, encoding:str=None):
                                 None,
                                 content_data)
 
-        # switch encoding according to user input
-        return TcgTpmsCelEvent.encode(event, encoding)
+        # return basic CEL event
+        # can switch encoding by calling the TcgTpmsCelEvent.encoding()
+        return event
 
 class EventLogs:
     """EventLogs class.
@@ -251,7 +252,7 @@ def _parse(self) -> None:
         for event in self._runtime_data.splitlines():
             event_log = self._parse_ima_event_log(event)
             self._event_logs.append(
-                event_log.format_event_log(TcgEventLog.TCG_FORMAT_CEL_TLV))
+                event_log.format_event_log(TcgEventLog.TCG_FORMAT_CEL))
             self._count += 1
 
     def _parse_spec_id_event_log(self, data:bytes) -> (TcgEventLog, int):
@@ -452,22 +453,21 @@ def replay(event_logs:list) -> dict:
             # TODO: consider CEL-JSON/CEL-CBOR encoding later
             # extract common attributes from different formats, only consider TLV encoding for now
             if isinstance(event, TcgTpmsCelEvent):
-                content_type = event.content.type
+                content_type = event.content_type
                 # Align the Canonical types with TCG PCClient Event types
                 match content_type:
                     case TcgCelTypes.CEL_IMA_TEMPLATE:
                         event_type = TcgEventType.IMA_MEASUREMENT_EVENT
                     case TcgCelTypes.CEL_PCCLIENT_STD:
                         # For PCClient_STD event,
                         # the event type is store within the content attribute
-                        event_type = event.content.value[0].value
+                        # event_type = event.content.value[0].value
+                        event_type = event.content.event_type
 
                 # TODO: consider the NV_INDEX case later
-                imr_index = event.index.value
+                imr_index = event.index
 
-                digests = []
-                for d in event.digests.value:
-                    digests.append(TcgDigest(d.type, d.value))
+                digests = event.digests
             else:
                 event_type = event.event_type
                 # Skip EV_NO_ACTION event during replay as

common/python/cctrusted_base/tcgcel.py

@@ -5,6 +5,8 @@
 from abc import abstractmethod
 from cctrusted_base.tcg import TcgDigest
 from cctrusted_base.tcg import TcgAlgorithmRegistry
+from cctrusted_base.tcg import TcgEventType
+from cctrusted_base.eventlog import TcgImrEvent
 from cctrusted_base.binaryblob import BinaryBlob
 
 LOG = logging.getLogger(__name__)
@@ -83,33 +85,50 @@ def set_digests(self, digests):
 
     @property
     def content(self):
-        """Content of the event.a"""
+        """Content of the event."""
         return self._content
 
     def set_content(self, content):
         """Set formatted value for content."""
         self._content = content
 
+    @property
+    def content_type(self):
+        """Content type of event."""
+        return self._content_type
+
     def encoding(self):
         """Get the encoding format of the event"""
         return self._encoding
 
+    def to_pcclient_format(self):
+        """Convert CEL event log to PCClient format"""
+        if self._content_type == TcgCelTypes.CEL_IMA_TEMPLATE:
+            event = self.content.template_data
+            return TcgImrEvent(self._imr, TcgEventType.IMA_MEASUREMENT_EVENT,
+                               self._digests, len(event), event)
+        if self._content_type == TcgCelTypes.CEL_PCCLIENT_STD:
+            return TcgImrEvent(self._imr, self.content.event_type, self._digests,
+                               len(self.content.event_data), self.content.event_data)
+        LOG.error("Unsupported content to parse into TCG PCClient format.")
+        return None
+
     @staticmethod
-    def encode(obj, encoding:int=1):
+    def encode(obj, encoding:int=2):
         """Encode the CEL record in certain format"""
         match encoding:
-            # TCG_FORMAT_CEL_TLV = 1
-            case 1:
+            # TcgEventLog.TCG_FORMAT_CEL_TLV = 2
+            case 2:
                 # pylint: disable-next=w0212
                 obj._encoding = "TLV"
                 return TcgTpmsCelEvent._encoded_in_tlv(obj)
-            # TCG_FORMAT_CEL_JSON = 2
-            case 2:
+            # TcgEventLog.TCG_FORMAT_CEL_JSON = 3
+            case 3:
                 # pylint: disable-next=w0212
                 obj._encoding = "JSON"
                 return TcgTpmsCelEvent._encoded_in_json(obj)
-            # TCG_FORMAT_CEL_CBOR = 3
-            case 3:
+            # TcgEventLog.TCG_FORMAT_CEL_JSON = 4
+            case 4:
                 # pylint: disable-next=w0212
                 obj._encoding = "CBOR"
                 return TcgTpmsCelEvent._encoded_in_cbor(obj)