tpm2: add marshaling/unmarshaling layer

TPM commands need to be serialized (marshaled) to be sent to the
device, and the responses need to be de-serialized (unmarshaled) to be
properly interpreted by upper layers.

This layer does not exist in TPM1.2 coreboot implementation, all TPM
commands used there were hardcoded as binary arrays. Availability of
the marshaling/unmarshaling layer makes it much easier to add new TPM
commands to the code.

Command and response structures used in these functions are defined in
Parts 2 and 3 of the TCG issued document

   Trusted Platform Module Library
   Family "2.0"
   Level 00 Revision 01.16
   October 30, 2014

BRANCH=none
BUG=chrome-os-partner:50645
TEST=with the rest of the patches applied it is possible to
     successfully initialize firmware and kernel TPM spaces.

Change-Id: I80b3f971e347bb30ea08f820ec3dd27e1656c060
Signed-off-by: Martin Roth <martinroth@chromium.org>
Original-Commit-Id: 0782d9d452efb732e85d1503fccfcb4bf9f69a68
Original-Change-Id: I202276ef9a43c28b5f304f901ac5b91048878b76
Original-Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/353915
Original-Reviewed-by: Bill Richardson <wfrichar@chromium.org>
Original-Reviewed-by: Darren Krahn <dkrahn@chromium.org>
Reviewed-on: https://review.coreboot.org/15570
Tested-by: build bot (Jenkins)
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@googlemail.com>

1 files changed, 49 insertions, 0 deletions

diff --git a/src/lib/tpm2_marshaling.h b/src/lib/tpm2_marshaling.h
new file mode 100644
index 0000000000..69a345d731
--- /dev/null
+++ b/src/lib/tpm2_marshaling.h
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2016 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#ifndef __SRC_LIB_TPM2_MARSHALING_H
+#define __SRC_LIB_TPM2_MARSHALING_H
+
+#include "tpm2_tlcl_structures.h"
+
+/* The below functions are used to serialize/deserialize TPM2 commands. */
+
+/**
+ * tpm_marshal_command
+ *
+ * Given a structure containing a TPM2 command, serialize the structure for
+ * sending it to the TPM.
+ *
+ * @command: code of the TPM2 command to marshal
+ * @tpm_command_body: a pointer to the command specific structure
+ * @buffer: buffer where command is marshaled to
+ * @buffer_size: size of the buffer
+ *
+ * Returns number of bytes placed in the buffer, or -1 on error.
+ *
+ */
+int tpm_marshal_command(TPM_CC command, void *tpm_command_body,
+			void *buffer, int buffer_size);
+
+/**
+ * tpm_unmarshal_response
+ *
+ * Given a buffer received from the TPM in response to a certain command,
+ * deserialize the buffer into the expeced response structure.
+ *
+ * struct tpm2_response is a union of all possible responses.
+ *
+ * @command: code of the TPM2 command for which a response is unmarshaled
+ * @response_body: buffer containing the serialized response.
+ * @response_size: number of bytes in the buffer containing response
+ *
+ * Returns a pointer to the deserialized response or NULL in case of
+ * unmarshaling problems.
+ */
+struct tpm2_response *tpm_unmarshal_response(TPM_CC command,
+					     void *response_body,
+					     int response_size);
+
+#endif // __SRC_LIB_TPM2_MARSHALING_H