From 0f31ae47d76b9c8258e493cfd85ab58f3d925309 Mon Sep 17 00:00:00 2001
From: Tom Roeder <tmroeder@google.com>
Date: Fri, 26 Apr 2019 17:14:19 -0700
Subject: [PATCH] Add a tpm-startup example.

This is used in setting up a software TPM emulator for testing. It sends
the startup command, which is normally not needed for user-level
libraries.
---
 examples/tpm-startup/startup.go | 41 +++++++++++++++++++++++++++++++++
 tpm/constants.go                | 11 +++++++++
 tpm/tpm.go                      |  6 +++++
 tpm/tpm_test.go                 | 13 +++++++++++
 4 files changed, 71 insertions(+)
 create mode 100644 examples/tpm-startup/startup.go

diff --git a/examples/tpm-startup/startup.go b/examples/tpm-startup/startup.go
new file mode 100644
index 00000000..ada470de
--- /dev/null
+++ b/examples/tpm-startup/startup.go
@@ -0,0 +1,41 @@
+// Copyright (c) 2019, Google LLC. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+
+	"github.com/google/go-tpm/tpm"
+)
+
+func main() {
+	var tpmname = flag.String("tpm", "/dev/tpm0", "The path to the TPM device to use")
+	flag.Parse()
+
+	rwc, err := tpm.OpenTPM(*tpmname)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Couldn't open the TPM file %s: %s\n", *tpmname, err)
+		return
+	}
+
+	if err := tpm.Startup(rwc, tpm.StartupClear); err != nil {
+		fmt.Fprintf(os.Stderr, "Couldn't start up the TPM: %s\n", err)
+		return
+	}
+
+	return
+}
diff --git a/tpm/constants.go b/tpm/constants.go
index 3b5b4f5f..fad3b7eb 100644
--- a/tpm/constants.go
+++ b/tpm/constants.go
@@ -50,6 +50,7 @@ const (
 	ordMakeIdentity         uint32 = 0x00000079
 	ordActivateIdentity     uint32 = 0x0000007A
 	ordReadPubEK            uint32 = 0x0000007C
+	ordStartup              uint32 = 0x00000099
 	ordOwnerReadInternalPub uint32 = 0x00000081
 	ordFlushSpecific        uint32 = 0x000000BA
 	ordPcrReset             uint32 = 0x000000C8
@@ -162,6 +163,16 @@ const (
 	authPrivUseOnly byte = 0x03
 )
 
+type StartupMode uint16
+
+// The startup modes for the Startup command.
+const (
+	_ StartupMode = iota
+	StartupClear
+	StartupWithState
+	StartupDeactivated
+)
+
 // fixedQuote is the fixed constant string used in quoteInfo.
 var fixedQuote = [4]byte{byte('Q'), byte('U'), byte('O'), byte('T')}
 
diff --git a/tpm/tpm.go b/tpm/tpm.go
index 2ab9dc5d..26591307 100644
--- a/tpm/tpm.go
+++ b/tpm/tpm.go
@@ -1254,6 +1254,12 @@ func ForceClear(rw io.ReadWriter) error {
 	in := []interface{}{}
 	out := []interface{}{}
 	_, err := submitTPMRequest(rw, tagRQUCommand, ordForceClear, in, out)
+	return err
+}
 
+// Startup starts a TPM. This is not necessary for hardware TPMs, but it is
+// sometimes needed for software emulators.
+func Startup(rw io.ReadWriter, mode StartupMode) error {
+	_, err := submitTPMRequest(rw, tagRQUCommand, ordStartup, []interface{}{mode}, nil)
 	return err
 }
diff --git a/tpm/tpm_test.go b/tpm/tpm_test.go
index fdfb18e9..9b7ca21d 100644
--- a/tpm/tpm_test.go
+++ b/tpm/tpm_test.go
@@ -554,3 +554,16 @@ func TestForceClear(t *testing.T) {
 		t.Fatal("Couldn't clear the TPM without owner auth in physical presence mode:", err)
 	}
 }
+
+func TestStartup(t *testing.T) {
+	// This only works if startup has not yet been performed. On TPM 1.2
+	// hardware, this happens at a lower level in the stack. However, this
+	// can be tested against emulators.
+	t.Skip()
+	rwc := openTPMOrSkip(t)
+	defer rwc.Close()
+
+	if err := Startup(rwc, StartupClear); err != nil {
+		t.Fatal("Couldn't start the TPM")
+	}
+}