enable auth agent forward on server

console_unix.go

@@ -9,6 +9,7 @@ import (
 	"os/signal"
 	"os/user"
 	"strconv"
+	"strings"
 	"syscall"
 
 	"github.com/containerd/console"
@@ -109,13 +110,29 @@ func setUserEnv(_cmd *exec.Cmd, u *user.User, attr *syscall.SysProcAttr) {
 	}
 	_uid, _ := strconv.ParseUint(u.Uid, 10, 32)
 	_gid, _ := strconv.ParseUint(u.Gid, 10, 32)
+
+	_cmd.Env = append(_cmd.Env, fmt.Sprintf("HOME=%s", u.HomeDir))
+	_cmd.Env = append(_cmd.Env, fmt.Sprintf("LOGNAME=%s", u.Name))
+	_cmd.Dir = u.HomeDir
+
+	if os.Getuid() != 0 {
+		return
+	}
+
 	if attr.Credential == nil {
 		attr.Credential = &syscall.Credential{}
 	}
+
 	attr.Credential.Uid = uint32(_uid)
 	attr.Credential.Gid = uint32(_gid)
+	for _, _env := range _cmd.Env {
+		ss := strings.Split(_env, "=")
+		if ss[0] == "SSH_AUTH_SOCK" {
+			os.Chown(ss[1], int(_uid), int(_gid))
+		}
+		if ss[0] == "SSH_TTY" {
+			os.Chown(ss[1], int(_uid), 0)
+		}
+	}
 
-	_cmd.Env = append(_cmd.Env, fmt.Sprintf("HOME=%s", u.HomeDir))
-	_cmd.Env = append(_cmd.Env, fmt.Sprintf("LOGNAME=%s", u.Name))
-	_cmd.Dir = u.HomeDir
 }

obfscp/scp.go

@@ -102,13 +102,7 @@ func createSFTPConn(host, user string, cfg *options) (*sftp.Client, error) {
 	if cfg.Passwd == "" && cfg.PrivateKey == "" {
 		var pkeys []ssh.Signer
 		if aconn, err := net.Dial("unix", os.Getenv("SSH_AUTH_SOCK")); err == nil {
-			//auths = append(auths, ssh.PublicKeysCallback(agent.NewClient(aconn).Signers))
-			if signers, err := agent.NewClient(aconn).Signers(); err == nil {
-				log.Debugf("add private key from agent")
-				pkeys = append(pkeys, signers...)
-			} else {
-				log.Debugf("get key from agent failed: %s", err)
-			}
+			auths = append(auths, ssh.PublicKeysCallback(agent.NewClient(aconn).Signers))
 		} else {
 			log.Debugf("dial to agent failed: %s", err)
 		}

obfssh/ssh.go

@@ -117,13 +117,7 @@ func main() {
 			defer agentConn.Close()
 			log.Debugf("add auth method with agent %s", os.Getenv("SSH_AUTH_SOCK"))
 			agentClient = agent.NewClient(agentConn)
-			//auth = append(auth, ssh.PublicKeysCallback(agentClient.Signers))
-			signers, err := agentClient.Signers()
-			if err == nil {
-				pkeys = append(pkeys, signers...)
-			} else {
-				log.Debugf("get key from agent failed: %s", err)
-			}
+			auth = append(auth, ssh.PublicKeysCallback(agentClient.Signers))
 		} else {
 			log.Debugf("connect to agent failed")
 		}

server.go

@@ -4,6 +4,7 @@ import (
 	"encoding/binary"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"net"
 	"os"
 	"os/exec"
@@ -322,6 +323,50 @@ func (s *session) handleWindowChange(payload []byte) bool {
 	return true
 }
 
+func (sc *Server) handleAuthAgentForward(sess *session) bool {
+	f, err := ioutil.TempFile("", "agent-")
+	if err != nil {
+		log.Errorln(err)
+		return false
+	}
+
+	p := f.Name()
+	f.Close()
+	os.Remove(p)
+
+	l, err := net.Listen("unix", p)
+	if err != nil {
+		log.Errorln(err)
+		return false
+	}
+
+	sess.env = append(sess.env, fmt.Sprintf("SSH_AUTH_SOCK=%s", p))
+
+	sc.forwardedPorts[p] = l
+
+	go func() {
+		defer os.Remove(p)
+		for {
+			c, err := l.Accept()
+			if err != nil {
+				log.Errorln(err)
+				break
+			}
+			go func(c net.Conn) {
+				ch, req, err := sc.sshConn.OpenChannel("auth-agent@openssh.com", nil)
+				if err != nil {
+					c.Close()
+					log.Errorln(err)
+					return
+				}
+				go ssh.DiscardRequests(req)
+				PipeAndClose(ch, c)
+			}(c)
+		}
+	}()
+	return true
+}
+
 func (sc *Server) handleSession(newch ssh.NewChannel) {
 	ch, req, err := newch.Accept()
 	if err != nil {
@@ -346,6 +391,8 @@ func (sc *Server) handleSession(newch ssh.NewChannel) {
 			ret = sess.handleEnv(r.Payload)
 		case "window-change":
 			ret = sess.handleWindowChange(r.Payload)
+		case "auth-agent-req@openssh.com":
+			ret = sc.handleAuthAgentForward(sess)
 		case "signal":
 			log.Debugln("got signal")
 			ret = true