cloudflared-mirror/sshserver/host_keys.go

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//+build !windows
package sshserver
import (
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"encoding/pem"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"github.com/gliderlabs/ssh"
"github.com/pkg/errors"
)
const (
rsaFilename = "ssh_host_rsa_key"
ecdsaFilename = "ssh_host_ecdsa_key"
)
func (s *SSHServer) configureHostKeys() error {
if _, err := os.Stat(systemConfigPath); os.IsNotExist(err) {
if err := os.MkdirAll(systemConfigPath, 0755); err != nil {
return errors.Wrap(err, fmt.Sprintf("Error creating %s directory", systemConfigPath))
}
}
if err := s.configureHostKey(s.ensureECDSAKeyExists); err != nil {
return err
}
if err := s.configureHostKey(s.ensureRSAKeyExists); err != nil {
return err
}
return nil
}
func (s *SSHServer) configureHostKey(keyFunc func() (string, error)) error {
path, err := keyFunc()
if err != nil {
return err
}
if err := s.SetOption(ssh.HostKeyFile(path)); err != nil {
return errors.Wrap(err, "Could not set SSH host key")
}
return nil
}
func (s *SSHServer) ensureRSAKeyExists() (string, error) {
keyPath := filepath.Join(systemConfigPath, rsaFilename)
if _, err := os.Stat(keyPath); os.IsNotExist(err) {
key, err := rsa.GenerateKey(rand.Reader, 2048)
if err != nil {
return "", errors.Wrap(err, "Error generating RSA host key")
}
privateKey := &pem.Block{
Type: "RSA PRIVATE KEY",
Bytes: x509.MarshalPKCS1PrivateKey(key),
}
if err = writePrivateKey(keyPath, privateKey); err != nil {
return "", err
}
s.logger.Debug("Created new RSA SSH host key: ", keyPath)
}
return keyPath, nil
}
func (s *SSHServer) ensureECDSAKeyExists() (string, error) {
keyPath := filepath.Join(systemConfigPath, ecdsaFilename)
if _, err := os.Stat(keyPath); os.IsNotExist(err) {
key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
if err != nil {
return "", errors.Wrap(err, "Error generating ECDSA host key")
}
keyBytes, err := x509.MarshalECPrivateKey(key)
if err != nil {
return "", errors.Wrap(err, "Error marshalling ECDSA key")
}
privateKey := &pem.Block{
Type: "EC PRIVATE KEY",
Bytes: keyBytes,
}
if err = writePrivateKey(keyPath, privateKey); err != nil {
return "", err
}
s.logger.Debug("Created new ECDSA SSH host key: ", keyPath)
}
return keyPath, nil
}
func writePrivateKey(keyPath string, privateKey *pem.Block) error {
if err := ioutil.WriteFile(keyPath, pem.EncodeToMemory(privateKey), 0600); err != nil {
return errors.Wrap(err, fmt.Sprintf("Error writing host key to %s", keyPath))
}
return nil
}