1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
|
// Copyright (c) 2018, 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 tpmutil
import (
"io"
"github.com/google/go-tpm/tpmutil/tbs"
)
// winTPMBuffer is a ReadWriteCloser to access the TPM in Windows.
type winTPMBuffer struct {
context tbs.Context
outBuffer []byte
}
// Executes the TPM command specified by commandBuffer (at Normal Priority), returning the number
// of bytes in the command and any error code returned by executing the TPM command. Command
// response can be read by calling Read().
func (rwc *winTPMBuffer) Write(commandBuffer []byte) (int, error) {
// TPM spec defines longest possible response to be maxTPMResponse.
rwc.outBuffer = rwc.outBuffer[:maxTPMResponse]
outBufferLen, err := rwc.context.SubmitCommand(
tbs.NormalPriority,
commandBuffer,
rwc.outBuffer,
)
if err != nil {
rwc.outBuffer = rwc.outBuffer[:0]
return 0, err
}
// Shrink outBuffer so it is length of response.
rwc.outBuffer = rwc.outBuffer[:outBufferLen]
return len(commandBuffer), nil
}
// Provides TPM response from the command called in the last Write call.
func (rwc *winTPMBuffer) Read(responseBuffer []byte) (int, error) {
if len(rwc.outBuffer) == 0 {
return 0, io.EOF
}
lenCopied := copy(responseBuffer, rwc.outBuffer)
// Cut out the piece of slice which was just read out, maintaining original slice capacity.
rwc.outBuffer = append(rwc.outBuffer[:0], rwc.outBuffer[lenCopied:]...)
return lenCopied, nil
}
func (rwc *winTPMBuffer) Close() error {
return rwc.context.Close()
}
// OpenTPM creates a new instance of a ReadWriteCloser which can interact with a
// Windows TPM.
func OpenTPM() (io.ReadWriteCloser, error) {
tpmContext, err := tbs.CreateContext(tbs.TPMVersion20, tbs.IncludeTPM12|tbs.IncludeTPM20)
rwc := &winTPMBuffer{
context: tpmContext,
outBuffer: make([]byte, 0, maxTPMResponse),
}
return rwc, err
}
// FromContext creates a new instance of a ReadWriteCloser which can
// interact with a Windows TPM, using the specified TBS handle.
func FromContext(ctx tbs.Context) io.ReadWriteCloser {
return &winTPMBuffer{
context: ctx,
outBuffer: make([]byte, 0, maxTPMResponse),
}
}
|
