libstb/trustedboot: Introduce new eventlog implementation

This new implementation uses the recently introduced standard TSS library,
reducing maintenance burden in skiboot side.
We have yet to switch over this new implementation and to remove the old
one in future commits.

Signed-off-by: Mauro S. M. Rodrigues <maurosr@linux.vnet.ibm.com>
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>

2 files changed, 156 insertions, 0 deletions

diff --git a/libstb/tss2/eventlog.c b/libstb/tss2/eventlog.c
new file mode 100644
index 0000000..f69db4b
--- /dev/null
+++ b/libstb/tss2/eventlog.c
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+/* Copyright 2020 IBM Corp. */
+
+#include <skiboot.h>
+
+#include <eventlog.h>
+#include <eventlib.h>
+#include <ibmtss/tssmarshal.h>
+
+
+int load_eventlog(TpmLogMgr *logmgr, uint8_t *eventlog_ptr,
+		  uint32_t eventlog_size)
+{
+	TCG_PCR_EVENT2 *event2 = NULL;
+	TCG_PCR_EVENT *event = NULL;
+	uint8_t *log_ptr, *ptr;
+	uint32_t size;
+	int rc = 0;
+
+	event = zalloc(sizeof(TCG_PCR_EVENT));
+	if(!event){
+		rc = 1;
+		goto cleanup;
+	}
+
+	event2 = zalloc(sizeof(TCG_PCR_EVENT2));
+	if(!event2){
+		rc = 1;
+		goto cleanup;
+	}
+
+	logmgr->logMaxSize = eventlog_size;
+	logmgr->eventLogInMem = eventlog_ptr;
+	logmgr->logSize = 0;
+
+	log_ptr = logmgr->eventLogInMem;
+	size = sizeof(TCG_PCR_EVENT);
+
+	//first event in the log is a header
+	rc = TSS_EVENT_Line_LE_Unmarshal(event, &log_ptr, &size);
+	if(rc)
+	{
+		prlog(PR_INFO, "Couldn't read event log header event, rc=%d",
+		      rc);
+		rc = 1;
+		goto cleanup;
+	}
+	//now iterate through all events
+	ptr = log_ptr;
+	do {
+		size = sizeof(TCG_PCR_EVENT2);
+		rc = TSS_EVENT2_Line_LE_Unmarshal(event2, &ptr, &size);
+		/* something went wrong in parsing (invalid values) or
+		 * digest.count is 0 - which doesn't make sense - we stop.
+		 */
+		if (rc || event2->digests.count == 0 )
+			break;
+		log_ptr = ptr;
+	} while(1);
+	logmgr->logSize = log_ptr - logmgr->eventLogInMem;
+	logmgr->newEventPtr = log_ptr;
+
+cleanup:
+	free(event);
+	free(event2);
+	return rc;
+}
+
+int add_to_eventlog(TpmLogMgr *logmgr, TCG_PCR_EVENT2 *event)
+{
+	uint32_t size = sizeof(TCG_PCR_EVENT2), rc = 0;
+	uint16_t written = 0, ev_size =0;
+
+	/* Calling Marshal function with a NULL buffer to obtain the event size.
+	 * It's a well known and safe pattern used in TSS code.
+	 * Then check if an event that larger will fit in evenlog buffer, and
+	 * only after success here marshal it to eventlog buffer pointed by
+	 * logmgr->newEventPtr.
+	 */
+	TSS_EVENT2_Line_LE_Marshal(event, &ev_size, NULL, &size);
+	if(logmgr->logSize + ev_size > logmgr->logMaxSize){
+		return 1;
+	}
+	rc = TSS_EVENT2_Line_LE_Marshal(event, &written,
+				     &(logmgr->newEventPtr), &size);
+	if(rc)
+		return rc;
+	logmgr->logSize += ev_size;
+
+	return rc;
+}
+
+int build_event(TCG_PCR_EVENT2 *event, TPMI_DH_PCR pcrHandle,
+		TPMI_ALG_HASH *hashes, uint8_t hashes_len,
+		const uint8_t **digests, uint32_t event_type,
+		const char* logmsg, uint32_t logmsg_len)
+{
+       uint16_t alg_digest_size;
+       uint32_t size;
+
+	memset(event, 0, sizeof(TCG_PCR_EVENT2));
+	event->pcrIndex = pcrHandle;
+	event->eventType = event_type;
+	event->digests.count = hashes_len;
+
+	size = sizeof(TPMI_ALG_HASH);
+	for (int i=0; i < event->digests.count; i++){
+		event->digests.digests[i].hashAlg = hashes[i];
+
+		TSS_TPMI_ALG_HASH_Marshalu(hashes+i, &alg_digest_size, NULL, &size);
+
+		if (alg_digest_size == 0)
+			return 1;
+		memcpy(&(event->digests.digests[i].digest), digests[i],
+		       strlen(digests[i]) > alg_digest_size ?
+				strlen(digests[i]) : alg_digest_size);
+
+	}
+
+	event->eventSize = logmsg_len;
+	memset(&(event->event), 0, sizeof(event->event));
+	memcpy(&(event->event), logmsg,
+	       event->eventSize > TCG_EVENT_LEN_MAX ?
+			TCG_EVENT_LEN_MAX - 1: event->eventSize);
+	return 0;
+}
diff --git a/libstb/tss2/eventlog.h b/libstb/tss2/eventlog.h
new file mode 100644
index 0000000..dd4a1d7
--- /dev/null
+++ b/libstb/tss2/eventlog.h
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+/* Copyright 2020 IBM Corp. */
+
+#ifndef __EVENTLOG_H
+#define __EVENTLOG_H
+
+#include <ibmtss/TPM_Types.h>
+#include <eventlib.h>
+
+#define MAX_TPM_LOG_MSG 128
+#define MAX_VENDOR_INFO_LEN 255
+
+struct _TpmLogMgr
+{
+	uint32_t logSize;
+	uint32_t logMaxSize;
+	uint8_t* newEventPtr;
+	uint8_t* eventLogInMem;
+};
+typedef struct _TpmLogMgr TpmLogMgr;
+
+
+int load_eventlog(TpmLogMgr *logmgr, uint8_t* eventlog_ptr,
+		  uint32_t eventlog_size);
+int add_to_eventlog(TpmLogMgr *logmgr, TCG_PCR_EVENT2 *event);
+int build_event(TCG_PCR_EVENT2 *event, TPMI_DH_PCR pcrHandle,
+                TPMI_ALG_HASH *hashes, uint8_t hashes_len,
+		const uint8_t **digests, uint32_t event_type,
+		const char* logmsg, uint32_t logmsg_len);
+#endif //__EVENTLOG_H