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Tunnel rough work-in-progress; data sent (wrong length) and CSOTunClose handling needs work, but it's a start...

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This commit is contained in:
Russ Magee 2018-10-28 19:17:47 -07:00
parent 1e6da733a2
commit 632f24354b
3 changed files with 42 additions and 53 deletions
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11
hkexnet/consts.go
View file

@ -33,8 +33,8 @@ type KEXAlg uint8
// Extended exit status codes - indicate comm/pty issues
// rather than remote end normal UNIX exit codes
const (
CSENone = 1024 + iota
CSEBadAuth // Failed login password
CSENone = 1024 + iota
//CSEBadAuth // Failed login password
CSETruncCSO // No CSOExitStatus in payload
CSEStillOpen // Channel closed unexpectedly
CSEExecFail // cmd.Start() (exec) failed
@ -50,8 +50,11 @@ const (
CSONone = iota // No error, normal packet
CSOHmacInvalid // HMAC mismatch detected on remote end
CSOTermSize // set term size (rows:cols)
CSOTunReq // client tunnel open request (dstport)
CSOTunAck // server tunnel open ack (tunport)
CSOTunReq // client tunnel open request (dstport)
CSOTunAck // server tunnel open ack (tunport)
CSOTunData // packet contains [rport:data]
CSOTunClose // request to close connection (tunnel stays open)
CSOTunRefused // tunnel has died or could not be established to rport
CSOExitStatus // Remote cmd exit status
CSOChaff // Dummy packet, do not pass beyond decryption
)

59
hkexnet/hkexnet.go
View file

@ -73,30 +73,6 @@ type (
szMax uint // max size in bytes
}
// Tunnels
// --
// 1. client is given (lport, remhost, rport) by local user
// 2. client sends [CSOTunReq:rport] to server
// client=> [CSOTunReq:rport] =>remhost
// t := TunEndpoint{dataPort: lport, peer: remhost}
//
// remhost allocates dynamic (Tport)
// t := TunEndpoint{dataPort: rport, peer: client, tunPort: Tport}
//
// remhost spawns goroutine forwarding data between (Tport,rport)
// client<= [CSOTunAck:Tport] <=remhost
// t.tunPort = Tport
//
// client spawns goroutine forwarding data between (lport,Tport)
// --
// TunEndpoint [securePort:peer:dataPort]
TunEndpoint struct {
TunPort uint16
Peer string //net.Addr
DataPort uint16
}
// Conn is a connection wrapping net.Conn with KEX & session state
Conn struct {
kex KEXAlg // KEX/KEM propsal (client -> server)
@ -109,8 +85,7 @@ type (
Cols uint16
chaff ChaffConfig
tuns []TunEndpoint
tuns map[uint16]chan []byte
closeStat *CSOType // close status (CSOExitStatus)
r cipher.Stream //read cipherStream
@ -127,7 +102,7 @@ var (
// Return string (suitable as map key) for a tunnel endpoint
func (t *TunEndpoint) String() string {
return fmt.Sprintf("[%d:%s:%d]", t.DataPort, t.Peer, t.TunPort)
return fmt.Sprintf("[%d:%s:%d]", t.Lport, t.Peer, t.Rport)
}
func _initLogging(d bool, c string, f logger.Priority) {
@ -261,12 +236,6 @@ func _new(kexAlg KEXAlg, conn *net.Conn) (hc *Conn, e error) {
}
func (hc *Conn) applyConnExtensions(extensions ...string) {
//fmt.Printf("CSENone:%d CSEBadAuth:%d CSETruncCSO:%d CSEStillOpen:%d CSEExecFail:%d CSEPtyExecFail:%d\n",
// CSENone, CSEBadAuth, CSETruncCSO, CSEStillOpen, CSEExecFail, CSEPtyExecFail)
//fmt.Printf("CSONone:%d CSOHmacInvalid:%d CSOTermSize:%d CSOExitStatus:%d CSOChaff:%d\n",
// CSONone, CSOHmacInvalid, CSOTermSize, CSOExitStatus, CSOChaff)
for _, s := range extensions {
switch s {
case "C_AES_256":
@ -821,16 +790,20 @@ func (hc Conn) Read(b []byte) (n int, err error) {
}
hc.Close()
} else if ctrlStatOp == CSOTunReq {
// This should ONLY be sent from client -> server!
// TODO: Hmm. should this package (hkexnet) take a 'server'/'client' context
// in order to know how to handle mis-uses?
addrs, _ := net.InterfaceAddrs()
t := TunEndpoint{Peer: addrs[0].String()}
t.TunPort = binary.BigEndian.Uint16(payloadBytes)
//fmt.Sscanf(string(payloadBytes), "%d", &t.tunPort)
Log.Notice(fmt.Sprintf("[TODO: Client Tunnel Open Request - traffic for server %s, port %d]\n", t.Peer, t.TunPort))
} else if ctrlStatOp == CSOTunAck {
Log.Notice("[Server Tunnel Open Ack - TODO]\n")
// Client wants a tunnel set up - args [lport:rport]
lport := binary.BigEndian.Uint16(payloadBytes)
rport := binary.BigEndian.Uint16(payloadBytes[2:4])
startServerTunnel(&hc, lport, rport)
} else if ctrlStatOp == CSOTunData {
lport := binary.BigEndian.Uint16(payloadBytes)
rport := binary.BigEndian.Uint16(payloadBytes[2:4])
fmt.Printf("[Got CSOTunData: [lport %d:rport %d] data:%v\n", lport, rport, payloadBytes[4:])
hc.tuns[rport] <- payloadBytes[4:]
} else if ctrlStatOp == CSOTunClose {
lport := binary.BigEndian.Uint16(payloadBytes)
rport := binary.BigEndian.Uint16(payloadBytes[2:4])
fmt.Printf("[Got CSOTunClose: [lport %d:rport %d]\n", lport, rport)
hc.tuns[rport] = nil
} else {
hc.dBuf.Write(payloadBytes)
//log.Printf("hc.dBuf: %s\n", hex.Dump(hc.dBuf.Bytes()))

25
hkexsh/hkexsh.go
View file

@ -337,12 +337,27 @@ func rejectUserMsg() string {
return "Begone, " + spinsult.GetSentence() + "\r\n"
}
func requestTunnel(c *hkexnet.Conn, dp uint16, p string /*net.Addr*/, tp uint16) (t hkexnet.TunEndpoint) {
t = hkexnet.TunEndpoint{DataPort: dp, Peer: p, TunPort: tp}
// Transmit request to server for it to set up the remote end of a tunnel
//
// Server responds with [CSOTunAck:rport] or [CSOTunRefused:rport]
func requestTunnel(hc *hkexnet.Conn, lp uint16, p string /*net.Addr*/, rp uint16) (t hkexnet.TunEndpoint) {
var bTmp bytes.Buffer
binary.Write(&bTmp, binary.BigEndian, t.DataPort)
c.WritePacket(bTmp.Bytes(), hkexnet.CSOTunReq)
binary.Write(&bTmp, binary.BigEndian, lp)
binary.Write(&bTmp, binary.BigEndian, rp)
hc.WritePacket(bTmp.Bytes(), hkexnet.CSOTunReq)
// Server should reply immediately with success (lport:rport) or
// refusal (lport:0)
var lportReply, rportReply uint16
errL := binary.Read(hc, binary.BigEndian, &lportReply)
errR := binary.Read(hc, binary.BigEndian, &rportReply)
if errL == nil && errR == nil {
fmt.Printf("Server established tunnel [%d:%d]\n", lportReply, rportReply)
hkexnet.StartClientTunnel(hc, lp, rp)
} else {
fmt.Println("FAILED reading remPort")
}
t = hkexnet.TunEndpoint{Lport: lportReply, Peer: p, Rport: rportReply}
return
}
@ -631,8 +646,6 @@ func main() {
}
if shellMode {
// TODO: tunnel setup would be here or within doShellMode()
// TESTING - tunnel
remAddrs, _ := net.LookupHost(remoteHost)
t := requestTunnel(&conn, 6001, remAddrs[0], 7001)