func (s *server) handleChanReq(chanReq ssh.NewChannel, authInfo map[string]string) {
if chanReq.ChannelType() != "session" {
chanReq.Reject(ssh.Prohibited, "channel type is not a session")
return
}
ch, reqs, err := chanReq.Accept()
if err != nil {
log.Errorf("fail to accept channel request %v", err)
return
}
for {
req := <-reqs
switch req.Type {
case "env":
case "exec":
s.handleExec(ch, req, authInfo)
return
default:
ch.Write([]byte(fmt.Sprintf("request type %q not allowed\r\n", req.Type)))
ch.Close()
return
}
}
}
/* logChannel returns a logger which can be used to log channel activities to a
file in the directory ldir. The logger as well as the filename are
returned. */
func logChannel(
ldir string,
nc ssh.NewChannel,
) (*log.Logger, *os.File, string, error) {
/* Log file is named after the channel time and type */
logName := filepath.Join(
ldir,
time.Now().Format(LOGFORMAT)+"-"+nc.ChannelType(),
)
/* Open the file */
lf, err := os.OpenFile(
logName,
os.O_WRONLY|os.O_APPEND|os.O_CREATE|os.O_EXCL,
0600,
)
if nil != err {
return nil, nil, "", err
}
return log.New(
//lf,
io.MultiWriter(lf, os.Stderr), /* DEBUG */
"",
log.LstdFlags|log.Lmicroseconds,
), lf, logName, nil
}
func handleChannel(chanRequest ssh.NewChannel) {
handle, err := NewHandle(chanRequest.ChannelType())
if err != nil {
config.Log.Debug("wrong handler %v", err)
chanRequest.Reject(ssh.UnknownChannelType, err.Error())
return
}
ch, reqs, err := chanRequest.Accept()
if err != nil {
config.Log.Debug("fail to accept channel request %v", err)
return
}
defer ch.Close()
for req := range reqs {
done, err := handle.Request(ch, req)
if err != nil {
config.Log.Debug("request errored out %v", err)
_, err := ch.Write([]byte(fmt.Sprintf("%v\r\n", err)))
if err != nil {
config.Log.Debug(err.Error())
}
}
if done {
return
}
}
}
// HandleChannel handles one SSH channel
func (c *Client) HandleChannel(newChannel ssh.NewChannel) error {
if newChannel.ChannelType() != "session" {
log.Debugf("Unknown channel type: %s", newChannel.ChannelType())
newChannel.Reject(ssh.UnknownChannelType, "unknown channel type")
return nil
}
channel, requests, err := newChannel.Accept()
if err != nil {
log.Errorf("newChannel.Accept failed: %v", err)
return err
}
c.ChannelIdx++
log.Debugf("HandleChannel.channel (client=%d channel=%d)", c.Idx, c.ChannelIdx)
log.Debug("Creating pty...")
c.Pty, c.Tty, err = pty.Open()
if err != nil {
log.Errorf("pty.Open failed: %v", err)
return nil
}
c.HandleChannelRequests(channel, requests)
return nil
}
func (s *Session) HandleDirectChannel(newChannel ssh.NewChannel) (bool, ssh.RejectionReason) {
data, err := UnmarshalTunnelData(newChannel.ExtraData())
if err != nil {
return false, ssh.UnknownChannelType
}
// look up session by name
session, host, port := s.Gateway().LookupSessionService(data.Host, uint16(data.Port))
if session == nil {
return false, ssh.ConnectionFailed
}
// found the service, attempt to open a channel
data.Host = host
data.Port = uint32(port)
c2, err := session.OpenChannel("forwarded-tcpip", MarshalTunnelData(data))
if err != nil {
return false, ssh.ConnectionFailed
}
defer func() {
if c2 != nil {
c2.Close()
}
}()
// accept the channel
channel, requests, err := newChannel.Accept()
if err != nil {
return false, ssh.ResourceShortage
}
// cannot return false from this point on
// also need to accepted close the channel
defer func() {
if channel != nil {
if err := channel.Close(); err != nil {
glog.Warningf("failed to close accepted channel: %s", err)
}
}
}()
c, err := NewChannel(s, channel, newChannel.ChannelType(), newChannel.ExtraData())
if err != nil {
glog.Errorf("failed to create accepted channel: %s", err)
return true, 0
}
s.AddChannel(c)
// no failure
go c.HandleRequests(requests)
go c.HandleTunnelChannel(c2)
// do not close channel on exit
channel = nil
c2 = nil
return true, 0
}
func sshHandleChannel(conn net.Conn, newChannel ssh.NewChannel) {
// Channels have a type, depending on the application level protocol
// intended. In the case of a shell, the type is "session" and ServerShell
// may be used to present a simple terminal interface.
if newChannel.ChannelType() != "session" {
newChannel.Reject(ssh.UnknownChannelType, "unknown channel type")
return
}
channel, requests, err := newChannel.Accept()
if err != nil {
log.Errorln(err)
return
}
// Sessions have out-of-band requests such as "shell", "pty-req" and "env".
// Here we handle only the "shell" request.
go func(in <-chan *ssh.Request) {
for req := range in {
ok := false
switch req.Type {
case "shell":
ok = true
if len(req.Payload) > 0 {
// We don't accept any commands, only the default shell.
ok = false
}
case "pty-req":
ok = true
}
req.Reply(ok, nil)
}
}(requests)
term := terminal.NewTerminal(channel, "> ")
go func() {
defer channel.Close()
for {
line, err := term.ReadLine()
start := time.Now().UnixNano()
if err != nil {
if err != io.EOF {
log.Errorln(err)
}
return
}
sshReportChan <- uint64(len(line))
// just echo the message
log.Debugln("ssh received: ", line)
term.Write([]byte(line))
term.Write([]byte{'\r', '\n'})
stop := time.Now().UnixNano()
log.Info("ssh %v %vns", conn.RemoteAddr(), uint64(stop-start))
}
}()
}
func (sshClient *sshClient) rejectNewChannel(newChannel ssh.NewChannel, reason ssh.RejectionReason, message string) {
// TODO: log more details?
log.WithContextFields(
LogFields{
"channelType": newChannel.ChannelType(),
"rejectMessage": message,
"rejectReason": reason,
}).Warning("reject new channel")
newChannel.Reject(reason, message)
}
func (s *Server) HandleNewChannel(session *Session, newChannel ssh.NewChannel) {
log.Printf("New Channel: %s", newChannel)
switch newChannel.ChannelType() {
case "direct-tcpip":
s.ChannelForward(session, newChannel)
default:
log.Printf("Unknown SSH channel type: %s", newChannel.ChannelType())
newChannel.Reject(ssh.UnknownChannelType, "connection flow not supported by sshmux")
}
}
func (server *SshServer) handleChannel(user string, newChannel ssh.NewChannel) {
if t := newChannel.ChannelType(); t != "session" {
newChannel.Reject(ssh.UnknownChannelType, fmt.Sprintf("unknown channel type: %s", t))
return
}
connection, requests, err := newChannel.Accept()
if err != nil {
fmt.Printf("Could not accept channel (%s)", err)
return
}
defer connection.Close()
logfile, err := os.Create(fmt.Sprintf("%s_%s", user, storyLogFilename(server.story)))
if err != nil {
panic(err)
}
defer logfile.Close()
logger := log.New(logfile, "", log.LstdFlags)
terminal := terminal.NewTerminal(connection, "")
zsshterm := &gork.ZSshTerminal{Term: terminal}
zm, err := gork.NewZMachine(server.mem, server.header, zsshterm, logger)
if err != nil {
fmt.Println(err)
return
}
go func() {
for req := range requests {
switch req.Type {
case "shell":
if len(req.Payload) == 0 {
req.Reply(true, nil)
}
case "pty-req":
termLen := req.Payload[3]
w, h := parseDims(req.Payload[termLen+4:])
terminal.SetSize(w, h)
case "window-change":
w, h := parseDims(req.Payload)
terminal.SetSize(w, h)
}
}
}()
defer func() {
recover()
}()
zm.InterpretAll()
}
func handleChannel(c ssh.NewChannel) {
if t := c.ChannelType(); t != "session" {
log.Println("rejected unknown channel type:", t)
c.Reject(ssh.UnknownChannelType, "unknown channel type")
}
connection, requests, err := c.Accept()
if err != nil {
log.Println("channel not accepted:", err)
return
}
bash := exec.Command("/bin/bash")
close := func() {
connection.Close()
_, err := bash.Process.Wait()
if err != nil {
log.Println("bash not exited:", err)
}
log.Println("session closed")
}
bashf, err := pty.Start(bash)
if err != nil {
log.Println("pty not started:", err)
close()
return
}
var once sync.Once
go func() {
io.Copy(connection, bashf)
once.Do(close)
}()
go func() {
io.Copy(bashf, connection)
once.Do(close)
}()
go func() {
for req := range requests {
log.Println("got request:", req.Type, "want reply:", req.WantReply)
switch req.Type {
case "shell":
if len(req.Payload) == 0 {
req.Reply(true, nil)
}
case "pty-req":
termLen := req.Payload[3]
w, h := parseDims(req.Payload[termLen+4:])
SetWinsize(bashf.Fd(), w, h)
req.Reply(true, nil)
case "window-change":
w, h := parseDims(req.Payload)
SetWinsize(bashf.Fd(), w, h)
}
}
}()
}
func (u *UrlDispatcher) Dispatch(c context.Context, conn *ssh.ServerConn, ch ssh.NewChannel) {
defer conn.Close()
// Get channel type
chType := ch.ChannelType()
// Parse channel URI
uri, err := url.ParseRequestURI(chType)
if err != nil {
u.Logger.Warn("Error parsing channel type", "type", chType, "err", err)
ch.Reject(InvalidChannelType, "invalid channel URI")
return
} else if reject(chType, uri, ch, u.Logger) {
return
}
chType = uri.Path
// Parse query params
values, err := url.ParseQuery(uri.RawQuery)
if err != nil {
u.Logger.Warn("Error parsing query params", "values", values, "err", err)
ch.Reject(InvalidQueryParams, "invalid query params in channel type")
return
}
// Determine if channel is acceptable (has a registered handler)
if !u.Router.HasRoute(chType) {
u.Logger.Info("UnknownChannelType", "type", chType)
ch.Reject(ssh.UnknownChannelType, chType)
return
}
// Otherwise, accept the channel
channel, requests, err := ch.Accept()
if err != nil {
u.Logger.Warn("Error creating channel", "type", chType, "err", err)
ch.Reject(ChannelAcceptError, chType)
return
}
// Handle the channel
err = u.Router.Handle(&router.UrlContext{
Path: uri.Path,
Context: c,
Values: values,
Channel: channel,
Requests: requests,
})
if err != nil {
u.Logger.Warn("Error handling channel", "type", chType, "err", err)
ch.Reject(ChannelHandleError, fmt.Sprintf("error handling channel: %s", err.Error()))
return
}
}
func (s *sshServer) handleChannel(newChannel ssh.NewChannel) error {
if newChannel.ChannelType() != "session" {
newChannel.Reject(ssh.UnknownChannelType, "unknown channel type")
return nil
}
channel, requests, err := newChannel.Accept()
if err != nil {
log.Println("newChannel accept failed: ", err)
return nil
}
return s.handleRequests(channel, requests)
}
func handleChanReq(chanReq ssh.NewChannel) {
if chanReq.ChannelType() != "session" {
chanReq.Reject(ssh.UnknownChannelType, "unknown channel type")
return
}
channel, requests, err := chanReq.Accept()
if err != nil {
return
}
exitloop := false
for {
select {
case req := <-requests:
if req == nil {
continue
}
if req.Type == "exec" {
handleExec(channel, req)
if req.WantReply {
req.Reply(true, nil)
}
exitloop = true
}
req.Reply(false, nil)
case <-time.After(3 * time.Second):
log.Println("no exec chanreq received, time out")
exitloop = true
break
}
if exitloop {
break
}
}
/*
todo: return exit status:
byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel
string "exit-status"
boolean FALSE
uint32 exit_status
*/
channel.Close()
}
func (svr *sshServer) handleChanReq(chanReq ssh.NewChannel) {
fmt.Fprintf(sshServerDebugStream, "channel request: %v, extra: '%v'\n", chanReq.ChannelType(), hex.EncodeToString(chanReq.ExtraData()))
switch chanReq.ChannelType() {
case "session":
if ch, reqs, err := chanReq.Accept(); err != nil {
fmt.Fprintf(sshServerDebugStream, "fail to accept channel request: %v\n", err)
chanReq.Reject(ssh.ResourceShortage, "channel accept failure")
} else {
chsvr := &sshSessionChannelServer{
sshChannelServer: &sshChannelServer{svr, chanReq, ch, reqs},
env: append([]string{}, os.Environ()...),
}
chsvr.handle()
}
default:
chanReq.Reject(ssh.UnknownChannelType, "channel type is not a session")
}
}
func (server *Server) handleChannel(newChannel ssh.NewChannel, conn *ssh.ServerConn) {
channelType := newChannel.ChannelType()
if channelType != "session" {
newChannel.Reject(ssh.UnknownChannelType,
fmt.Sprintf("Unknown SSH Channel Type: %s, only `session` is supported", channelType))
server.Logger.Errorf("Rejected SSH Channel Request from %s due to unknown channel type: %s",
conn.RemoteAddr().String(), newChannel.ChannelType())
return
}
channel, requests, err := newChannel.Accept()
if err != nil {
newChannel.Reject(ssh.ConnectionFailed, "Failed to accept SSH Channel Request, developers are working on it.")
server.Logger.Errorf("Rejected SSH Channel Request from %s due to accept request failure: %s",
conn.RemoteAddr().String(), err)
return
}
server.Logger.Debugf("Accepted new SSH Channel Request from %s", conn.RemoteAddr().String())
server.handleRequest(channel, requests, conn)
}
func (s *Session) HandleChannel(newChannel ssh.NewChannel) {
glog.V(9).Infof("new channel: type = %s, data = %v", newChannel.ChannelType(), newChannel.ExtraData())
ok := false
rejection := ssh.UnknownChannelType
switch newChannel.ChannelType() {
case "session":
ok, rejection = s.HandleSessionChannel(newChannel)
case "direct-tcpip":
ok, rejection = s.HandleDirectChannel(newChannel)
}
if !ok {
// reject the channel
if err := newChannel.Reject(rejection, ""); err != nil {
glog.Warningf("failed to reject channel: %s", err)
}
}
}
func handleChanReq(chanReq ssh.NewChannel) {
if chanReq.ChannelType() != "session" {
chanReq.Reject(ssh.Prohibited, "channel type is not a session")
return
}
ch, reqs, err := chanReq.Accept()
if err != nil {
log.Println("fail to accept channel request", err)
return
}
req := <-reqs
if req.Type != "exec" {
ch.Write([]byte("request type '" + req.Type + "' is not 'exec'\r\n"))
ch.Close()
return
}
handleExec(ch, req)
}
func (u *SimpleDispatcher) Dispatch(c context.Context, conn *ssh.ServerConn, ch ssh.NewChannel) {
defer conn.Close()
var ctx *Context
if u.PanicHandler != nil {
if rcv := recover(); rcv != nil {
u.PanicHandler.Handle(ctx, rcv)
}
}
// Get channel type
chType := ch.ChannelType()
handler, ok := u.Handlers[chType]
if !ok {
return
}
// Otherwise, accept the channel
channel, requests, err := ch.Accept()
if err != nil {
u.Logger.Warn("Error creating channel", "type", chType, "err", err)
ch.Reject(ChannelAcceptError, chType)
return
}
// Handle the channel
ctx = &Context{
Context: c,
Channel: channel,
Requests: requests,
}
err = handler.Handle(ctx)
if err != nil {
u.Logger.Warn("Error handling channel", "type", chType, "err", err)
ch.Reject(ChannelHandleError, fmt.Sprintf("error handling channel: %s", err.Error()))
return
}
}
func handleChannel(newChannel ssh.NewChannel) {
// Since we're handling a shell, we expect a
// channel type of "session". The also describes
// "x11", "direct-tcpip" and "forwarded-tcpip"
// channel types.
if t := newChannel.ChannelType(); t != "session" {
newChannel.Reject(ssh.UnknownChannelType, fmt.Sprintf("unknown channel type: %s", t))
return
}
// At this point, we have the opportunity to reject the client's
// request for another logical connection
connection, _, err := newChannel.Accept()
if err != nil {
log.Printf("Could not accept channel (%s)", err)
return
}
defer connection.Close()
connection.Write([]byte("Hello!\n"))
}
func (s *SSHServer) handleChannel(newChannel ssh.NewChannel) {
defer GinkgoRecover()
Expect(newChannel.ChannelType()).To(Equal("session"))
if s.RejectSession {
Expect(newChannel.Reject(ssh.ConnectionFailed, "session rejected")).To(Succeed())
return
}
channel, requests, err := newChannel.Accept()
Expect(err).NotTo(HaveOccurred())
go func() {
defer GinkgoRecover()
for request := range requests {
switch request.Type {
case "exec":
payloadLen := binary.BigEndian.Uint32(request.Payload[:4])
Expect(request.Payload).To(HaveLen(int(payloadLen) + 4))
s.CommandChan <- string(request.Payload[4:])
Expect(request.Reply(true, nil)).To(Succeed())
_, err := channel.SendRequest("exit-status", false, []byte{0, 0, 0, s.CommandExitStatus})
Expect(err).To(Succeed())
channel.Close()
break
}
}
}()
go func() {
defer GinkgoRecover()
io.Copy(s.Data, channel)
}()
}
// Make new terminal from a session channel
func NewTerminal(conn *ssh.ServerConn, ch ssh.NewChannel) (*Terminal, error) {
if ch.ChannelType() != "session" {
return nil, errors.New("terminal requires session channel")
}
channel, requests, err := ch.Accept()
if err != nil {
return nil, err
}
term := Terminal{
*terminal.NewTerminal(channel, "Connecting..."),
sshConn{conn},
channel,
}
go term.listen(requests)
go func() {
// FIXME: Is this necessary?
conn.Wait()
channel.Close()
}()
return &term, nil
}
func (s *Session) HandleSessionChannel(newChannel ssh.NewChannel) (bool, ssh.RejectionReason) {
if len(newChannel.ExtraData()) > 0 {
// do not accept extra data in session channel request
return false, ssh.Prohibited
}
// accept the channel
channel, requests, err := newChannel.Accept()
if err != nil {
return false, ssh.ResourceShortage
}
// cannot return false from this point on
// also need to accepted close the channel
defer func() {
if channel != nil {
if err := channel.Close(); err != nil {
glog.Warningf("failed to close accepted channel: %s", err)
}
}
}()
c, err := NewChannel(s, channel, newChannel.ChannelType(), newChannel.ExtraData())
if err != nil {
glog.Errorf("failed to create accepted channel: %s", err)
return true, 0
}
s.AddChannel(c)
// no failure
go c.HandleRequests(requests)
go c.HandleSessionChannel()
// do not close channel on exit
channel = nil
return true, 0
}
func (s *Server) handleChannel(ch ssh.NewChannel) {
id := rand.Int()
s.Debug("Handling Channel", "id", id, "chan", ch.ChannelType())
if ch.ChannelType() != "session" {
s.Info("Received unknown channel type", "chan", ch.ChannelType())
ch.Reject(ssh.UnknownChannelType, "unknown channel type")
return
}
channel, requests, err := ch.Accept()
if err != nil {
s.Error("Failed to accept channe", "err", err)
return
}
var closer sync.Once
closeChannel := func() {
s.Debug("Closed Channel", "id", id)
channel.Close()
}
defer closer.Do(closeChannel)
for req := range requests {
spew.Dump(req.Type)
switch req.Type {
case "exec":
// Let it through
case "env":
if req.WantReply {
if err = req.Reply(true, nil); err != nil {
s.Error("Failed to ignore env command", "err", err)
}
}
continue
default:
s.Info("Received unhandled request type", "type", req.Type)
continue
}
r := &scpRequest{db: s.DB}
processors := []processor{
r.ParseSCPRequest, r.DownloadFile, r.EndConnectionGracefully,
}
for _, proc := range processors {
if err := proc(channel, req); err != nil {
fmt.Fprintln(channel, "failed to process request:", err.Error())
// log.Printf("%+v", err)
break
}
}
closer.Do(closeChannel)
}
}
/* rejectChannel tells the attacker the channel's been rejected by the real
server. It requires the error from the channel request to the real server, the
channel request log string, the channel request from the attacker, and the
logger for the connection. */
func rejectChannel(nce error, crl string, nc ssh.NewChannel, lg *log.Logger) {
/* Values to return to the attacker */
reason := ssh.Prohibited
message := nce.Error()
/* Try and get the real story */
if oce, ok := nce.(*ssh.OpenChannelError); ok {
reason = oce.Reason
message = oce.Message
}
lg.Printf(
"Channel Rejection %v Reason:%v Message:%q",
crl,
reason,
message,
)
/* Send the rejection */
if err := nc.Reject(reason, message); nil != err {
lg.Printf(
"Unable to respond to channel request of type %q: %v",
nc.ChannelType(),
err,
)
}
}
func handleChannel(newChannel ssh.NewChannel, rClient *ssh.Client) {
if newChannel.ChannelType() != "session" {
newChannel.Reject(ssh.UnknownChannelType, "unknown channel type: "+newChannel.ChannelType())
return
}
psChannel, psRequests, err := newChannel.Accept()
if err != nil {
panic("could not accept channel.")
}
sChannel, sRequests, err := rClient.OpenChannel(newChannel.ChannelType(), nil)
if err != nil {
panic("Failed to create session: " + err.Error())
}
go pipeRequests(psChannel, sChannel, psRequests, sRequests)
time.Sleep(50 * time.Millisecond)
go pipe(sChannel, psChannel)
go pipe(psChannel, sChannel)
}
// SessionForward performs a regular forward, providing the user with an
// interactive remote host selection if necessary. This forwarding type
// requires agent forwarding in order to work.
func (s *Server) SessionForward(session *Session, newChannel ssh.NewChannel, chans <-chan ssh.NewChannel) {
// Okay, we're handling this as a regular session
sesschan, sessReqs, err := newChannel.Accept()
if err != nil {
return
}
stderr := sesschan.Stderr()
remote := ""
switch len(session.Remotes) {
case 0:
sesschan.Close()
return
case 1:
remote = session.Remotes[0]
default:
comm := rw{Reader: sesschan, Writer: stderr}
if s.Interactive == nil {
remote, err = DefaultInteractive(comm, session)
} else {
remote, err = s.Interactive(comm, session)
}
if err != nil {
sesschan.Close()
return
}
}
fmt.Fprintf(stderr, "Connecting to %s\r\n", remote)
// Set up the agent
agentChan, agentReqs, err := session.Conn.OpenChannel("*****@*****.**", nil)
if err != nil {
fmt.Fprintf(stderr, "\r\n====== sshmux ======\r\n")
fmt.Fprintf(stderr, "sshmux requires either agent forwarding or secure channel forwarding.\r\n")
fmt.Fprintf(stderr, "Either enable agent forwarding (-A), or use a ssh -W proxy command.\r\n")
fmt.Fprintf(stderr, "For more info, see the sshmux wiki.\r\n")
sesschan.Close()
return
}
defer agentChan.Close()
go ssh.DiscardRequests(agentReqs)
// Set up the client
ag := agent.NewClient(agentChan)
clientConfig := &ssh.ClientConfig{
User: session.Conn.User(),
Auth: []ssh.AuthMethod{
ssh.PublicKeysCallback(ag.Signers),
},
}
client, err := ssh.Dial("tcp", remote, clientConfig)
if err != nil {
fmt.Fprintf(stderr, "Connect failed: %v\r\n", err)
sesschan.Close()
return
}
// Handle all incoming channel requests
go func() {
for newChannel = range chans {
if newChannel == nil {
return
}
channel2, reqs2, err := client.OpenChannel(newChannel.ChannelType(), newChannel.ExtraData())
if err != nil {
x, ok := err.(*ssh.OpenChannelError)
if ok {
newChannel.Reject(x.Reason, x.Message)
} else {
newChannel.Reject(ssh.Prohibited, "remote server denied channel request")
}
continue
}
channel, reqs, err := newChannel.Accept()
if err != nil {
channel2.Close()
continue
}
go proxy(reqs, reqs2, channel, channel2)
}
}()
// Forward the session channel
channel2, reqs2, err := client.OpenChannel("session", []byte{})
if err != nil {
fmt.Fprintf(stderr, "Remote session setup failed: %v\r\n", err)
sesschan.Close()
return
}
// Proxy the channel and its requests
maskedReqs := make(chan *ssh.Request, 1)
go func() {
for req := range sessReqs {
if req.Type == "*****@*****.**" {
continue
}
maskedReqs <- req
}
}()
proxy(maskedReqs, reqs2, sesschan, channel2)
}
func proxyChannel(c *ConnInsight, mcha ssh.Channel, mreq <-chan *ssh.Request, master ssh.NewChannel, client *SSHClient, killer <-chan struct{}) error {
do := new(sync.Once)
cochan, coreq, err := client.OpenChannel(master.ChannelType(), master.ExtraData())
checkError(err, fmt.Sprintf("Creating Client Channel for %s", client.RemoteAddr().String()))
if err != nil {
return err
}
stop := make(chan struct{})
endClose := func() { close(stop) }
flux.GoDefer("proxyChannelCopy", func() {
defer cochan.Close()
defer mcha.Close()
func() {
ploop:
for {
select {
case <-stop:
break ploop
case <-killer:
break ploop
case slx, ok := <-coreq:
if !ok {
return
}
Reply(slx, mcha, c)
switch slx.Type {
case "exit-status":
break ploop
}
case mlx, ok := <-mreq:
if !ok {
return
}
Reply(mlx, cochan, c)
switch mlx.Type {
case "exit-status":
break ploop
}
}
}
}()
})
mastercloser := io.ReadCloser(mcha)
slavecloser := io.ReadCloser(cochan)
wrapmaster := io.MultiWriter(mcha, c.Out())
wrapsl := io.MultiWriter(cochan, c.In())
flux.GoDefer("CopyToSlave", func() {
defer do.Do(endClose)
io.Copy(wrapsl, mastercloser)
})
flux.GoDefer("CopyToMaster", func() {
defer do.Do(endClose)
io.Copy(wrapmaster, slavecloser)
})
flux.GoDefer("CopyCloser", func() {
defer c.Close()
<-stop
mx := mastercloser.Close()
checkError(mx, "Master Writer Closer")
sx := slavecloser.Close()
checkError(sx, "Slave Writer Closer")
ex := client.Close()
checkError(ex, "Client Writer Closer")
})
return nil
}
func handleChannel(newChannel ssh.NewChannel, config *SSHTestServer) {
if t := newChannel.ChannelType(); t != "session" {
newChannel.Reject(ssh.UnknownChannelType, fmt.Sprintf("unknown channel type: %s", t))
return
}
connection, requests, err := newChannel.Accept()
if err != nil {
lo.G.Info("Could not accept channel (%s)", err)
return
}
bash := exec.Command("bash")
close := func() {
connection.Close()
_, err := bash.Process.Wait()
if err != nil {
lo.G.Info("Failed to exit bash (%s)", err)
}
lo.G.Info("Session closed")
}
lo.G.Info("Creating pty...")
bashf, err := pty.Start(bash)
if err != nil {
lo.G.Info("Could not start pty (%s)", err)
close()
return
}
var once sync.Once
var cmdBuffer = bytes.NewBufferString("")
multiBashf := io.MultiWriter(cmdBuffer, bashf)
go func() {
io.Copy(multiBashf, connection)
lo.G.Debug("done reading executor")
once.Do(close)
}()
go func() {
for {
if strings.Contains(cmdBuffer.String(), config.SSHCommandMatch) {
io.Copy(connection, bytes.NewBuffer(config.FakeResponseBytes))
cmdBuffer.Reset()
}
}
}()
go func() {
io.Copy(cmdBuffer, bashf)
once.Do(close)
}()
go func() {
for req := range requests {
switch req.Type {
case "shell":
// We only accept the default shell
// (i.e. no command in the Payload)
if len(req.Payload) == 0 {
req.Reply(true, nil)
}
case "pty-req":
termLen := req.Payload[3]
w, h := parseDims(req.Payload[termLen+4:])
SetWinsize(bashf.Fd(), w, h)
// Responding true (OK) here will let the client
// know we have a pty ready for input
req.Reply(true, nil)
case "window-change":
w, h := parseDims(req.Payload)
SetWinsize(bashf.Fd(), w, h)
}
}
}()
}
/* handleChan handles a single channel request from sc, proxying it to the
client. General logging messages will be written to lg, and channel-specific
data and messages will be written to a new file in ldir. */
func handleChan(
nc ssh.NewChannel,
client ssh.Conn,
ldir string,
lg *log.Logger,
direction string,
) {
/* Log the channel request */
crl := fmt.Sprintf(
"Type:%q Data:%q Direction:%q",
nc.ChannelType(),
nc.ExtraData(),
direction,
)
/* Pass to server */
cc, creqs, err := client.OpenChannel(
nc.ChannelType(),
nc.ExtraData(),
)
if nil != err {
go rejectChannel(err, crl, nc, lg)
return
}
defer cc.Close()
/* Make channel to attacker, defer close */
ac, areqs, err := nc.Accept()
if nil != err {
lg.Printf(
"Unable to accept channel request of type %q: %v",
nc.ChannelType(),
err,
)
return
}
defer ac.Close()
/* Channel worked, make a logger for it */
clg, lf, clgn, err := logChannel(ldir, nc)
if nil != err {
lg.Printf(
"Unable to open log file for channel of type %q:%v",
nc.ChannelType(),
err,
)
return
}
defer lf.Close()
clg.Printf("Start of log")
/* Proxy requests on channels */
go handleReqs(areqs, Channel{oc: cc}, clg, "attacker->server")
go handleReqs(creqs, Channel{oc: ac}, clg, "server->attacker")
/* Log the channel */
lg.Printf("Channel %s Log:%q", crl, clgn)
/* Proxy comms */
wg := make(chan int, 4)
go ProxyChannel(
ac,
cc,
clg,
"server->attacker",
wg,
1,
)
go ProxyChannel(
cc,
ac,
clg,
"attacker->server",
wg,
1,
)
go ProxyChannel(
cc.Stderr(),
ac.Stderr(),
clg,
"attacker-(err)->server",
wg,
0,
)
go ProxyChannel(
ac.Stderr(),
cc.Stderr(),
clg,
"server-(err)->attacker",
wg,
0,
)
sum := 0
for i := range wg {
sum += i
if 2 <= sum {
break
}
}
/* TODO: Proxy comms */
}
func handleChannel(newChannel ssh.NewChannel) {
// Since we're handling a shell, we expect a
// channel type of "session". The also describes
// "x11", "direct-tcpip" and "forwarded-tcpip"
// channel types.
if t := newChannel.ChannelType(); t != "session" {
newChannel.Reject(ssh.UnknownChannelType, fmt.Sprintf("unknown channel type: %s", t))
return
}
// At this point, we have the opportunity to reject the client's
// request for another logical connection
connection, requests, err := newChannel.Accept()
if err != nil {
log.Printf("Could not accept channel (%s)", err)
return
}
// Fire up bash for this session
bash := exec.Command("bash")
// Prepare teardown function
close := func() {
connection.Close()
_, err := bash.Process.Wait()
if err != nil {
log.Printf("Failed to exit bash (%s)", err)
}
log.Printf("Session closed")
}
// Allocate a terminal for this channel
log.Print("Creating pty...")
bashf, err := pty.Start(bash)
if err != nil {
log.Printf("Could not start pty (%s)", err)
close()
return
}
//pipe session to bash and visa-versa
var once sync.Once
go func() {
io.Copy(connection, bashf)
once.Do(close)
}()
go func() {
io.Copy(bashf, connection)
once.Do(close)
}()
// Sessions have out-of-band requests such as "shell", "pty-req" and "env"
go func() {
for req := range requests {
switch req.Type {
case "shell":
// We only accept the default shell
// (i.e. no command in the Payload)
if len(req.Payload) == 0 {
req.Reply(true, nil)
}
case "pty-req":
termLen := req.Payload[3]
w, h := parseDims(req.Payload[termLen+4:])
SetWinsize(bashf.Fd(), w, h)
// Responding true (OK) here will let the client
// know we have a pty ready for input
req.Reply(true, nil)
case "window-change":
w, h := parseDims(req.Payload)
SetWinsize(bashf.Fd(), w, h)
}
}
}()
}