mirror of https://github.com/kubernetes/kops.git
112 lines
3.2 KiB
Go
112 lines
3.2 KiB
Go
// +build !windows
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// Copyright (c) 2018, Google LLC All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package tpmutil
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import (
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"fmt"
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"io"
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"net"
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"os"
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)
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// OpenTPM opens a channel to the TPM at the given path. If the file is a
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// device, then it treats it like a normal TPM device, and if the file is a
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// Unix domain socket, then it opens a connection to the socket.
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func OpenTPM(path string) (io.ReadWriteCloser, error) {
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// If it's a regular file, then open it
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var rwc io.ReadWriteCloser
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fi, err := os.Stat(path)
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if err != nil {
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return nil, err
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}
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if fi.Mode()&os.ModeDevice != 0 {
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var f *os.File
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f, err = os.OpenFile(path, os.O_RDWR, 0600)
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if err != nil {
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return nil, err
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}
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rwc = io.ReadWriteCloser(f)
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} else if fi.Mode()&os.ModeSocket != 0 {
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rwc = NewEmulatorReadWriteCloser(path)
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} else {
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return nil, fmt.Errorf("unsupported TPM file mode %s", fi.Mode().String())
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}
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return rwc, nil
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}
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// dialer abstracts the net.Dial call so test code can provide its own net.Conn
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// implementation.
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type dialer func(network, path string) (net.Conn, error)
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// EmulatorReadWriteCloser manages connections with a TPM emulator over a Unix
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// domain socket. These emulators often operate in a write/read/disconnect
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// sequence, so the Write method always connects, and the Read method always
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// closes. EmulatorReadWriteCloser is not thread safe.
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type EmulatorReadWriteCloser struct {
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path string
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conn net.Conn
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dialer dialer
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}
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// NewEmulatorReadWriteCloser stores information about a Unix domain socket to
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// write to and read from.
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func NewEmulatorReadWriteCloser(path string) *EmulatorReadWriteCloser {
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return &EmulatorReadWriteCloser{
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path: path,
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dialer: net.Dial,
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}
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}
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// Read implements io.Reader by reading from the Unix domain socket and closing
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// it.
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func (erw *EmulatorReadWriteCloser) Read(p []byte) (int, error) {
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// Read is always the second operation in a Write/Read sequence.
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if erw.conn == nil {
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return 0, fmt.Errorf("must call Write then Read in an alternating sequence")
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}
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n, err := erw.conn.Read(p)
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erw.conn.Close()
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erw.conn = nil
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return n, err
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}
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// Write implements io.Writer by connecting to the Unix domain socket and
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// writing.
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func (erw *EmulatorReadWriteCloser) Write(p []byte) (int, error) {
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if erw.conn != nil {
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return 0, fmt.Errorf("must call Write then Read in an alternating sequence")
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}
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var err error
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erw.conn, err = erw.dialer("unix", erw.path)
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if err != nil {
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return 0, err
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}
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return erw.conn.Write(p)
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}
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// Close implements io.Closer by closing the Unix domain socket if one is open.
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func (erw *EmulatorReadWriteCloser) Close() error {
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if erw.conn == nil {
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return fmt.Errorf("cannot call Close when no connection is open")
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}
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err := erw.conn.Close()
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erw.conn = nil
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return err
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}
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