107 lines
2.1 KiB
Go
107 lines
2.1 KiB
Go
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package main
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import (
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"fmt"
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"io"
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"io/ioutil"
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"os"
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"path/filepath"
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"sync"
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"github.com/gliderlabs/ssh"
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"github.com/sirupsen/logrus"
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gossh "golang.org/x/crypto/ssh"
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)
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type ServerConfig struct {
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ListenPort int
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KeysPath string
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HostKeyPath string
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}
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type Server struct {
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cfg *ServerConfig
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publicKeys []ssh.PublicKey
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mu *sync.Mutex
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}
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func NewServer(cfg *ServerConfig) (*Server, error) {
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if cfg.ListenPort == 0 {
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cfg.ListenPort = 2222
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}
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return &Server{
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cfg: cfg,
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mu: &sync.Mutex{},
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}, nil
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}
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func (s *Server) loadKeys() error {
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s.mu.Lock()
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defer s.mu.Unlock()
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if s.cfg.KeysPath == "" {
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return nil
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}
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keys, err := ioutil.ReadDir(s.cfg.KeysPath)
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if err != nil {
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return err
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}
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pubKeys := []ssh.PublicKey{}
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for _, k := range keys {
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logrus.Debugf("loading public key %s", k.Name())
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p := filepath.Join(s.cfg.KeysPath, k.Name())
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data, err := ioutil.ReadFile(p)
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if err != nil {
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return err
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}
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k, _, _, _, err := ssh.ParseAuthorizedKey(data)
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if err != nil {
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return err
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}
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pubKeys = append(pubKeys, k)
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}
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s.publicKeys = pubKeys
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return nil
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}
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func (s *Server) Run() error {
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if err := s.loadKeys(); err != nil {
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return err
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}
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ssh.Handle(func(s ssh.Session) {
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authorizedKey := gossh.MarshalAuthorizedKey(s.PublicKey())
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io.WriteString(s, fmt.Sprintf("pub key used by %s\n", s.User()))
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s.Write(authorizedKey)
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})
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pubKeyOption := ssh.PublicKeyAuth(func(ctx ssh.Context, key ssh.PublicKey) bool {
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return s.isAuthorized(ctx, key)
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})
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logrus.Infof("starting ssh server on port %d", s.cfg.ListenPort)
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opts := []ssh.Option{
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pubKeyOption,
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}
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if _, err := os.Stat(s.cfg.HostKeyPath); err == nil {
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opts = append(opts, ssh.HostKeyFile(s.cfg.HostKeyPath))
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}
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return ssh.ListenAndServe(fmt.Sprintf(":%d", s.cfg.ListenPort), nil, pubKeyOption)
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}
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func (s *Server) isAuthorized(ctx ssh.Context, key ssh.PublicKey) bool {
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for _, k := range s.publicKeys {
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if ssh.KeysEqual(key, k) {
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return true
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}
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}
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logrus.WithFields(logrus.Fields{
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"user": ctx.User(),
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"addr": ctx.RemoteAddr(),
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}).Warn("access denied")
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return false
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}
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