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"
)
var defaultHostKeyDir = filepath.Join(".cloudflared", "host_keys")
func (s *SSHProxy) configureHostKeys(hostKeyDir string) error {
if hostKeyDir == "" {
homeDir, err := os.UserHomeDir()
if err != nil {
return err
}
hostKeyDir = filepath.Join(homeDir, defaultHostKeyDir)
}
if _, err := os.Stat(hostKeyDir); os.IsNotExist(err) {
if err := os.MkdirAll(hostKeyDir, 0755); err != nil {
return errors.Wrap(err, fmt.Sprintf("Error creating %s directory", hostKeyDir))
}
}
if err := s.configureECDSAKey(hostKeyDir); err != nil {
return err
}
if err := s.configureRSAKey(hostKeyDir); err != nil {
return err
}
return nil
}
func (s *SSHProxy) configureRSAKey(basePath string) error {
keyPath := filepath.Join(basePath, 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.Debugf("Created new RSA SSH host key: %s", keyPath)
}
if err := s.SetOption(ssh.HostKeyFile(keyPath)); err != nil {
return errors.Wrap(err, "Could not set SSH RSA host key")
}
return nil
}
func (s *SSHProxy) configureECDSAKey(basePath string) error {
keyPath := filepath.Join(basePath, 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.Debugf("Created new ECDSA SSH host key: %s", keyPath)
}
if err := s.SetOption(ssh.HostKeyFile(keyPath)); err != nil {
return errors.Wrap(err, "Could not set SSH ECDSA host key")
}
return 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
}