mirror of
https://gogs.blitter.com/RLabs/xs
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975 lines
27 KiB
Go
975 lines
27 KiB
Go
// hkexnet.go - net.Conn compatible channel setup with encrypted/HMAC
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// negotiation
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// Copyright (c) 2017-2018 Russell Magee
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// Licensed under the terms of the MIT license (see LICENSE.mit in this
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// distribution)
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//
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// golang implementation by Russ Magee (rmagee_at_gmail.com)
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package hkexnet
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// TODO:
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// If key exchange algs other than the experimental HerraduraKEx are to
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// be supported, the Dial() and Accept() methods should take a kex param,
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// specifying which to use; and the client/server negotiation must then
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// prefix the channel setup with this param over the wire in order to decide
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// which is in use.
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//
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// DESIGN PRINCIPLE: There shall be no protocol features which enable
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// downgrade attacks. The server shall have final authority to accept or
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// reject any and all proposed KEx and connection parameters proposed by
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// clients at setup. Action on denial shall be a simple server disconnect
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// with possibly a status code sent so client can determine why connection
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// was denied (compare to how failed auth is communicated to client).
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// Implementation of HKEx-wrapped versions of the golang standard
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// net package interfaces, allowing clients and servers to simply replace
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// 'net.Dial' and 'net.Listen' with 'hkex.Dial' and 'hkex.Listen'
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// (though some extra methods are implemented and must be used
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// for things outside of the scope of plain sockets).
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import (
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"bytes"
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"crypto/cipher"
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"encoding/binary"
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"encoding/hex"
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"errors"
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"fmt"
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"hash"
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"io"
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"io/ioutil"
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"log"
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"log/syslog"
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"math/big"
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"math/rand"
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"net"
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"strings"
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"sync"
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"time"
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"blitter.com/go/hkexsh/herradurakex"
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kyber "git.schwanenlied.me/yawning/kyber.git"
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)
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/*---------------------------------------------------------------------*/
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const PAD_SZ = 32 // max size of padding applied to each packet
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const HMAC_CHK_SZ = 4 // leading bytes of HMAC to xmit for verification
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type (
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WinSize struct {
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Rows uint16
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Cols uint16
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}
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// chaffconfig captures attributes used to send chaff packets betwixt
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// client and server connections, to obscure true traffic timing and
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// patterns
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// see: https://en.wikipedia.org/wiki/chaff_(countermeasure)
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ChaffConfig struct {
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shutdown bool //set to inform chaffHelper to shut down
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enabled bool
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msecsMin uint //msecs min interval
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msecsMax uint //msecs max interval
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szMax uint // max size in bytes
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}
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//h *hkex.HerraduraKEx // TODO: make an interface?
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// Conn is a connection wrapping net.Conn with KEX & session state
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Conn struct {
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kex KEXAlg // KEX/KEM propsal (client -> server)
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m *sync.Mutex // (internal)
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c *net.Conn // which also implements io.Reader, io.Writer, ...
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cipheropts uint32 // post-KEx cipher/hmac options
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opts uint32 // post-KEx protocol options (caller-defined)
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WinCh chan WinSize
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Rows uint16
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Cols uint16
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chaff ChaffConfig
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closeStat *CSOType // close status (CSOExitStatus)
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r cipher.Stream //read cipherStream
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rm hash.Hash
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w cipher.Stream //write cipherStream
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wm hash.Hash
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dBuf *bytes.Buffer //decrypt buffer for Read()
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}
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)
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var (
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Log *syslog.Writer // reg. syslog output (no -d)
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)
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func _initLogging(d bool, c string, f syslog.Priority) {
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if Log == nil {
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Log, _ = syslog.New(f, fmt.Sprintf("%s:hkexnet", c))
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}
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if d {
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log.SetFlags(0) // syslog will have date,time
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log.SetOutput(Log)
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} else {
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log.SetOutput(ioutil.Discard)
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}
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}
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func Init(d bool, c string, f syslog.Priority) {
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_initLogging(d, c, f)
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}
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func (hc Conn) GetStatus() CSOType {
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return *hc.closeStat
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}
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func (hc *Conn) SetStatus(stat CSOType) {
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*hc.closeStat = stat
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log.Println("closeStat:", *hc.closeStat)
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}
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// ConnOpts returns the cipher/hmac options value, which is sent to the
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// peer but is not itself part of the KEx.
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//
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// (Used for protocol-level negotiations after KEx such as
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// cipher/HMAC algorithm options etc.)
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func (hc Conn) ConnOpts() uint32 {
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return hc.cipheropts
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}
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// SetConnOpts sets the cipher/hmac options value, which is sent to the
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// peer as part of KEx but not part of the KEx itself.
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//
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// opts - bitfields for cipher and hmac alg. to use after KEx
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func (hc *Conn) SetConnOpts(copts uint32) {
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hc.cipheropts = copts
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}
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// Opts returns the protocol options value, which is sent to the peer
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// but is not itself part of the KEx or connection (cipher/hmac) setup.
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//
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// Consumers of this lib may use this for protocol-level options not part
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// of the KEx or encryption info used by the connection.
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func (hc Conn) Opts() uint32 {
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return hc.opts
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}
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// SetOpts sets the protocol options value, which is sent to the peer
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// but is not itself part of the KEx or connection (cipher/hmac) setup.
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//
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// Consumers of this lib may use this for protocol-level options not part
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// of the KEx of encryption info used by the connection.
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//
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// opts - a uint32, caller-defined
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func (hc *Conn) SetOpts(opts uint32) {
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hc.opts = opts
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}
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func getkexalgnum(extensions ...string) (k KEXAlg) {
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k = KEX_HERRADURA256 // default
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for _, s := range extensions {
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switch s {
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case "KEX_HERRADURA256":
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k = KEX_HERRADURA256
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break //out of for
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case "KEX_HERRADURA512":
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k = KEX_HERRADURA512
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break //out of for
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case "KEX_HERRADURA1024":
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k = KEX_HERRADURA1024
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break //out of for
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case "KEX_HERRADURA2048":
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k = KEX_HERRADURA2048
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break //out of for
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case "KEX_KYBER512":
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k = KEX_KYBER512
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break //out of for
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case "KEX_KYBER768":
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k = KEX_KYBER768
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break //out of for
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case "KEX_KYBER1024":
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k = KEX_KYBER1024
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break //out of for
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}
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}
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return
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}
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// Return a new hkexnet.Conn
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//
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// Note this is internal: use Dial() or Accept()
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func _new(kexAlg KEXAlg, conn *net.Conn) (hc *Conn, e error) {
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// Set up stuff common to all KEx/KEM types
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hc = &Conn{kex: kexAlg,
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m: &sync.Mutex{},
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c: conn,
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closeStat: new(CSOType),
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WinCh: make(chan WinSize, 1),
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dBuf: new(bytes.Buffer)}
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*hc.closeStat = CSEStillOpen // open or prematurely-closed status
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// Set up KEx/KEM-specifics
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switch kexAlg {
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case KEX_HERRADURA256:
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fallthrough
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case KEX_HERRADURA512:
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fallthrough
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case KEX_HERRADURA1024:
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fallthrough
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case KEX_HERRADURA2048:
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log.Printf("[KEx alg %d accepted]\n", kexAlg)
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case KEX_KYBER512:
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fallthrough
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case KEX_KYBER768:
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fallthrough
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case KEX_KYBER1024:
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log.Printf("[KEx alg %d accepted]\n", kexAlg)
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default:
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// UNREACHABLE: _getkexalgnum() guarantees a valid KEX value
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hc.kex = KEX_HERRADURA256
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log.Printf("[KEx alg %d ?? defaults to %d]\n", kexAlg, hc.kex)
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}
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return
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}
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func (hc *Conn) applyConnExtensions(extensions ...string) {
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//fmt.Printf("CSENone:%d CSEBadAuth:%d CSETruncCSO:%d CSEStillOpen:%d CSEExecFail:%d CSEPtyExecFail:%d\n",
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// CSENone, CSEBadAuth, CSETruncCSO, CSEStillOpen, CSEExecFail, CSEPtyExecFail)
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//fmt.Printf("CSONone:%d CSOHmacInvalid:%d CSOTermSize:%d CSOExitStatus:%d CSOChaff:%d\n",
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// CSONone, CSOHmacInvalid, CSOTermSize, CSOExitStatus, CSOChaff)
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for _, s := range extensions {
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switch s {
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case "C_AES_256":
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log.Println("[extension arg = C_AES_256]")
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hc.cipheropts &= (0xFFFFFF00)
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hc.cipheropts |= CAlgAES256
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case "C_TWOFISH_128":
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log.Println("[extension arg = C_TWOFISH_128]")
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hc.cipheropts &= (0xFFFFFF00)
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hc.cipheropts |= CAlgTwofish128
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case "C_BLOWFISH_64":
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log.Println("[extension arg = C_BLOWFISH_64]")
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hc.cipheropts &= (0xFFFFFF00)
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hc.cipheropts |= CAlgBlowfish64
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case "C_CRYPTMT1":
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log.Println("[extension arg = C_CRYPTMT1]")
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hc.cipheropts &= (0xFFFFFF00)
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hc.cipheropts |= CAlgCryptMT1
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case "H_SHA256":
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log.Println("[extension arg = H_SHA256]")
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hc.cipheropts &= (0xFFFF00FF)
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hc.cipheropts |= (HmacSHA256 << 8)
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case "H_SHA512":
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log.Println("[extension arg = H_SHA512]")
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hc.cipheropts &= (0xFFFF00FF)
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hc.cipheropts |= (HmacSHA512 << 8)
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//default:
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// log.Printf("[Dial ext \"%s\" ignored]\n", s)
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}
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}
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}
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// randReader wraps rand.Read() in a struct that implements io.Reader
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// for use by the Kyber KEM methods.
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type randReader struct {
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}
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func (r randReader) Read(b []byte) (n int, e error) {
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n, e = rand.Read(b)
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return
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}
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func KyberDialSetup(c net.Conn, hc *Conn) (err error) {
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// Send hkexnet.Conn parameters to remote side
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// Alice, step 1: Generate a key pair.
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r := new(randReader)
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var alicePublicKey *kyber.PublicKey
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var alicePrivateKey *kyber.PrivateKey
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switch hc.kex {
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case KEX_KYBER512:
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alicePublicKey, alicePrivateKey, err = kyber.Kyber512.GenerateKeyPair(r)
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case KEX_KYBER768:
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alicePublicKey, alicePrivateKey, err = kyber.Kyber768.GenerateKeyPair(r)
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case KEX_KYBER1024:
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alicePublicKey, alicePrivateKey, err = kyber.Kyber1024.GenerateKeyPair(r)
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default:
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alicePublicKey, alicePrivateKey, err = kyber.Kyber768.GenerateKeyPair(r)
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}
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if err != nil {
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panic(err)
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}
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// Alice, step 2: Send the public key to Bob
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fmt.Fprintf(c, "0x%x\n0x%x:0x%x\n", alicePublicKey.Bytes(),
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hc.cipheropts, hc.opts)
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// [Bob, step 1-3], from which we read cipher text
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cipherB := make([]byte, 4096)
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fmt.Fscanf(c, "0x%x\n", &cipherB)
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//if err != nil {
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// return err
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//}
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log.Printf("[Got server ciphertext[]:%v]\n", cipherB)
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// Read cipheropts, session opts
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_, err = fmt.Fscanf(c, "0x%x:0x%x\n",
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&hc.cipheropts, &hc.opts)
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if err != nil {
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return err
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}
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// Alice, step 3: Decrypt the KEM cipher text.
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aliceSharedSecret := alicePrivateKey.KEMDecrypt(cipherB)
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log.Printf("[Derived sharedSecret:0x%x]\n", aliceSharedSecret)
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hc.r, hc.rm, err = hc.getStream(aliceSharedSecret)
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hc.w, hc.wm, err = hc.getStream(aliceSharedSecret)
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return
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}
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func HKExDialSetup(c net.Conn, hc *Conn) (err error) {
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var h *hkex.HerraduraKEx
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switch hc.kex {
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case KEX_HERRADURA256:
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h = hkex.New(256, 64)
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case KEX_HERRADURA512:
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h = hkex.New(512, 128)
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case KEX_HERRADURA1024:
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h = hkex.New(1024, 256)
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case KEX_HERRADURA2048:
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h = hkex.New(2048, 512)
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default:
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h = hkex.New(256, 64)
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}
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// Send hkexnet.Conn parameters to remote side
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// d is value for Herradura key exchange
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fmt.Fprintf(c, "0x%s\n0x%x:0x%x\n", h.D().Text(16),
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hc.cipheropts, hc.opts)
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// Read peer D over net.Conn (c)
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d := big.NewInt(0)
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_, err = fmt.Fscanln(c, d)
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if err != nil {
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return err
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}
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_, err = fmt.Fscanf(c, "0x%x:0x%x\n",
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&hc.cipheropts, &hc.opts)
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if err != nil {
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return err
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}
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h.SetPeerD(d)
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log.Printf("** local D:%s\n", h.D().Text(16))
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log.Printf("**(c)** peer D:%s\n", h.PeerD().Text(16))
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h.ComputeFA()
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log.Printf("**(c)** FA:%s\n", h.FA())
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hc.r, hc.rm, err = hc.getStream(h.FA().Bytes())
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hc.w, hc.wm, err = hc.getStream(h.FA().Bytes())
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return
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}
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func KyberAcceptSetup(c *net.Conn, hc *Conn) (err error) {
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// Bob, step 1: Deserialize Alice's public key from the binary encoding.
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alicePublicKey := big.NewInt(0)
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_, err = fmt.Fscanln(*c, alicePublicKey)
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log.Printf("[Got client pubKey:0x%x\n]", alicePublicKey)
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if err != nil {
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return err
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}
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_, err = fmt.Fscanf(*c, "0x%x:0x%x\n",
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&hc.cipheropts, &hc.opts)
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log.Printf("[Got cipheropts, opts:%v, %v]", hc.cipheropts, hc.opts)
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if err != nil {
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return err
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}
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var peerPublicKey *kyber.PublicKey
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switch hc.kex {
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case KEX_KYBER512:
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peerPublicKey, err = kyber.Kyber512.PublicKeyFromBytes(alicePublicKey.Bytes())
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case KEX_KYBER768:
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peerPublicKey, err = kyber.Kyber768.PublicKeyFromBytes(alicePublicKey.Bytes())
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case KEX_KYBER1024:
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peerPublicKey, err = kyber.Kyber1024.PublicKeyFromBytes(alicePublicKey.Bytes())
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default:
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peerPublicKey, err = kyber.Kyber768.PublicKeyFromBytes(alicePublicKey.Bytes())
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}
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if err != nil {
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panic(err)
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}
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// Bob, step 2: Generate the KEM cipher text and shared secret.
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r := new(randReader)
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cipherText, bobSharedSecret, err := peerPublicKey.KEMEncrypt(r)
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if err != nil {
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panic(err)
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}
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// Bob, step 3: Send the cipher text to Alice.
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//fmt.Println("cipherText:",cipherText)
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fmt.Fprintf(*c, "0x%x\n0x%x:0x%x\n", cipherText,
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hc.cipheropts, hc.opts)
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log.Printf("[Derived sharedSecret:0x%x]\n", bobSharedSecret)
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hc.r, hc.rm, err = hc.getStream(bobSharedSecret)
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hc.w, hc.wm, err = hc.getStream(bobSharedSecret)
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return
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}
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func HKExAcceptSetup(c *net.Conn, hc *Conn) (err error) {
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var h *hkex.HerraduraKEx
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switch hc.kex {
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case KEX_HERRADURA256:
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h = hkex.New(256, 64)
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case KEX_HERRADURA512:
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h = hkex.New(512, 128)
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case KEX_HERRADURA1024:
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h = hkex.New(1024, 256)
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case KEX_HERRADURA2048:
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h = hkex.New(2048, 512)
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default:
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h = hkex.New(256, 64)
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}
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// Read in hkexnet.Conn parameters over raw Conn c
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// d is value for Herradura key exchange
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d := big.NewInt(0)
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_, err = fmt.Fscanln(*c, d)
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log.Printf("[Got d:%v]", d)
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if err != nil {
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return err
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}
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_, err = fmt.Fscanf(*c, "0x%x:0x%x\n",
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&hc.cipheropts, &hc.opts)
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log.Printf("[Got cipheropts, opts:%v, %v]", hc.cipheropts, hc.opts)
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if err != nil {
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return err
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}
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h.SetPeerD(d)
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log.Printf("** D:%s\n", h.D().Text(16))
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log.Printf("**(s)** peerD:%s\n", h.PeerD().Text(16))
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h.ComputeFA()
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log.Printf("**(s)** FA:%s\n", h.FA())
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// Send D and cipheropts/conn_opts to peer
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fmt.Fprintf(*c, "0x%s\n0x%x:0x%x\n", h.D().Text(16),
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hc.cipheropts, hc.opts)
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hc.r, hc.rm, err = hc.getStream(h.FA().Bytes())
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hc.w, hc.wm, err = hc.getStream(h.FA().Bytes())
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return
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}
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|
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// Dial as net.Dial(), but with implicit key exchange to set up secure
|
|
// channel on connect
|
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//
|
|
// Can be called like net.Dial(), defaulting to C_AES_256/H_SHA256,
|
|
// or additional option arguments can be passed amongst the following:
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//
|
|
// "C_AES_256" | "C_TWOFISH_128"
|
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//
|
|
// "H_SHA256"
|
|
func Dial(protocol string, ipport string, extensions ...string) (hc Conn, err error) {
|
|
if Log == nil {
|
|
Init(false, "client", syslog.LOG_DAEMON|syslog.LOG_DEBUG)
|
|
}
|
|
|
|
// Open raw Conn c
|
|
c, err := net.Dial(protocol, ipport)
|
|
if err != nil {
|
|
return Conn{}, err
|
|
}
|
|
|
|
// Init hkexnet.Conn hc over net.Conn c
|
|
ret, err := _new(getkexalgnum(extensions...), &c)
|
|
if err != nil {
|
|
return Conn{}, err
|
|
}
|
|
hc = *ret
|
|
|
|
// Client has full control over Conn extensions. It's the server's
|
|
// responsibility to accept or reject the proposed parameters.
|
|
hc.applyConnExtensions(extensions...)
|
|
|
|
// Perform Key Exchange according to client-request algorithm
|
|
fmt.Fprintf(c, "%02x\n", hc.kex)
|
|
switch hc.kex {
|
|
case KEX_HERRADURA256:
|
|
fallthrough
|
|
case KEX_HERRADURA512:
|
|
fallthrough
|
|
case KEX_HERRADURA1024:
|
|
fallthrough
|
|
case KEX_HERRADURA2048:
|
|
log.Printf("[Setting up for KEX_HERRADURA %d]\n", hc.kex)
|
|
if HKExDialSetup(c, &hc) != nil {
|
|
return Conn{}, nil
|
|
}
|
|
case KEX_KYBER512:
|
|
fallthrough
|
|
case KEX_KYBER768:
|
|
fallthrough
|
|
case KEX_KYBER1024:
|
|
log.Printf("[Setting up for KEX_KYBER %d]\n", hc.kex)
|
|
if KyberDialSetup(c, &hc) != nil {
|
|
return Conn{}, nil
|
|
}
|
|
default:
|
|
return Conn{}, err
|
|
}
|
|
return
|
|
}
|
|
|
|
// Close a hkex.Conn
|
|
func (hc *Conn) Close() (err error) {
|
|
hc.DisableChaff()
|
|
s := make([]byte, 4)
|
|
binary.BigEndian.PutUint32(s, uint32(*hc.closeStat))
|
|
log.Printf("** Writing closeStat %d at Close()\n", *hc.closeStat)
|
|
hc.WritePacket(s, CSOExitStatus)
|
|
err = (*hc.c).Close()
|
|
Log.Notice(fmt.Sprintln("[Conn Closing]"))
|
|
return
|
|
}
|
|
|
|
// LocalAddr returns the local network address.
|
|
func (hc *Conn) LocalAddr() net.Addr {
|
|
return (*hc.c).LocalAddr()
|
|
}
|
|
|
|
// RemoteAddr returns the remote network address.
|
|
func (hc *Conn) RemoteAddr() net.Addr {
|
|
return (*hc.c).RemoteAddr()
|
|
}
|
|
|
|
// SetDeadline sets the read and write deadlines associated
|
|
// with the connection. It is equivalent to calling both
|
|
// SetReadDeadline and SetWriteDeadline.
|
|
//
|
|
// A deadline is an absolute time after which I/O operations
|
|
// fail with a timeout (see type Error) instead of
|
|
// blocking. The deadline applies to all future and pending
|
|
// I/O, not just the immediately following call to Read or
|
|
// Write. After a deadline has been exceeded, the connection
|
|
// can be refreshed by setting a deadline in the future.
|
|
//
|
|
// An idle timeout can be implemented by repeatedly extending
|
|
// the deadline after successful Read or Write calls.
|
|
//
|
|
// A zero value for t means I/O operations will not time out.
|
|
func (hc *Conn) SetDeadline(t time.Time) error {
|
|
return (*hc.c).SetDeadline(t)
|
|
}
|
|
|
|
// SetWriteDeadline sets the deadline for future Write calls
|
|
// and any currently-blocked Write call.
|
|
// Even if write times out, it may return n > 0, indicating that
|
|
// some of the data was successfully written.
|
|
// A zero value for t means Write will not time out.
|
|
func (hc *Conn) SetWriteDeadline(t time.Time) error {
|
|
return (*hc.c).SetWriteDeadline(t)
|
|
}
|
|
|
|
// SetReadDeadline sets the deadline for future Read calls
|
|
// and any currently-blocked Read call.
|
|
// A zero value for t means Read will not time out.
|
|
func (hc *Conn) SetReadDeadline(t time.Time) error {
|
|
return (*hc.c).SetReadDeadline(t)
|
|
}
|
|
|
|
/*---------------------------------------------------------------------*/
|
|
|
|
// HKExListener is a Listener conforming to net.Listener
|
|
//
|
|
// See go doc net.Listener
|
|
type HKExListener struct {
|
|
l net.Listener
|
|
}
|
|
|
|
// Listen for a connection
|
|
//
|
|
// See go doc net.Listen
|
|
func Listen(protocol string, ipport string) (hl HKExListener, e error) {
|
|
if Log == nil {
|
|
Init(false, "server", syslog.LOG_DAEMON|syslog.LOG_DEBUG)
|
|
}
|
|
|
|
l, err := net.Listen(protocol, ipport)
|
|
if err != nil {
|
|
return HKExListener{nil}, err
|
|
}
|
|
Log.Notice(fmt.Sprintf("[Listening on %s]\n", ipport))
|
|
hl.l = l
|
|
return
|
|
}
|
|
|
|
// Close a hkex Listener - closes the Listener.
|
|
// Any blocked Accept operations will be unblocked and return errors.
|
|
//
|
|
// See go doc net.Listener.Close
|
|
func (hl HKExListener) Close() error {
|
|
Log.Notice(fmt.Sprintln("[Listener Closed]"))
|
|
return hl.l.Close()
|
|
}
|
|
|
|
// Addr returns a the listener's network address.
|
|
//
|
|
// See go doc net.Listener.Addr
|
|
func (hl HKExListener) Addr() net.Addr {
|
|
return hl.l.Addr()
|
|
}
|
|
|
|
// Accept a client connection, conforming to net.Listener.Accept()
|
|
//
|
|
// See go doc net.Listener.Accept
|
|
func (hl *HKExListener) Accept() (hc Conn, err error) {
|
|
// Open raw Conn c
|
|
c, err := hl.l.Accept()
|
|
if err != nil {
|
|
return Conn{}, err
|
|
}
|
|
Log.Notice(fmt.Sprintln("[net.Listener Accepted]"))
|
|
|
|
// Read KEx alg proposed by client
|
|
var kexAlg KEXAlg
|
|
//! NB. Was using fmt.FScanln() here, but integers with a leading zero
|
|
// were being mis-scanned? (is it an octal thing? Investigate.)
|
|
_, err = fmt.Fscanf(c, "%02x\n", &kexAlg)
|
|
if err != nil {
|
|
return Conn{}, err
|
|
}
|
|
log.Printf("[Client proposed KEx alg: %v]\n", kexAlg)
|
|
// --
|
|
|
|
ret, err := _new(kexAlg, &c)
|
|
if err != nil {
|
|
return Conn{}, err
|
|
}
|
|
hc = *ret
|
|
|
|
switch hc.kex {
|
|
case KEX_HERRADURA256:
|
|
fallthrough
|
|
case KEX_HERRADURA512:
|
|
fallthrough
|
|
case KEX_HERRADURA1024:
|
|
fallthrough
|
|
case KEX_HERRADURA2048:
|
|
log.Printf("[Setting up for KEX_HERRADURA %d]\n", hc.kex)
|
|
if HKExAcceptSetup(&c, &hc) != nil {
|
|
return Conn{}, err
|
|
}
|
|
case KEX_KYBER512:
|
|
fallthrough
|
|
case KEX_KYBER768:
|
|
fallthrough
|
|
case KEX_KYBER1024:
|
|
log.Printf("[Setting up for KEX_KYBER %d]\n", hc.kex)
|
|
if KyberAcceptSetup(&c, &hc) != nil {
|
|
return Conn{}, err
|
|
}
|
|
default:
|
|
return Conn{}, err
|
|
}
|
|
log.Println("[hc.Accept successful]")
|
|
return
|
|
}
|
|
|
|
/*---------------------------------------------------------------------*/
|
|
|
|
// Read into a byte slice
|
|
//
|
|
// See go doc io.Reader
|
|
func (hc Conn) Read(b []byte) (n int, err error) {
|
|
//log.Printf("[Decrypting...]\r\n")
|
|
for {
|
|
//log.Printf("hc.dBuf.Len(): %d\n", hc.dBuf.Len())
|
|
if hc.dBuf.Len() > 0 /* len(b) */ {
|
|
break
|
|
}
|
|
|
|
var ctrlStatOp uint8
|
|
var hmacIn [HMAC_CHK_SZ]uint8
|
|
var payloadLen uint32
|
|
|
|
// Read ctrl/status opcode (CSOHmacInvalid on hmac mismatch)
|
|
err = binary.Read(*hc.c, binary.BigEndian, &ctrlStatOp)
|
|
log.Printf("[ctrlStatOp: %v]\n", ctrlStatOp)
|
|
if ctrlStatOp == CSOHmacInvalid {
|
|
// Other side indicated channel tampering, close channel
|
|
hc.Close()
|
|
return 1, errors.New("** ALERT - remote end detected HMAC mismatch - possible channel tampering **")
|
|
}
|
|
|
|
// Read the hmac and payload len first
|
|
err = binary.Read(*hc.c, binary.BigEndian, &hmacIn)
|
|
// Normal client 'exit' from interactive session will cause
|
|
// (on server side) err.Error() == "<iface/addr info ...>: use of closed network connection"
|
|
if err != nil {
|
|
if err == io.EOF || strings.HasSuffix(err.Error(), "use of closed network connection") {
|
|
Log.Notice(fmt.Sprintln("[Client hung up]"))
|
|
} else {
|
|
log.Println(err)
|
|
}
|
|
return 0, err
|
|
}
|
|
|
|
err = binary.Read(*hc.c, binary.BigEndian, &payloadLen)
|
|
if err != nil {
|
|
if err.Error() != "EOF" {
|
|
Log.Err(fmt.Sprintln("[2]unexpected Read() err:", err))
|
|
}
|
|
}
|
|
|
|
if payloadLen > MAX_PAYLOAD_LEN {
|
|
Log.Err(fmt.Sprintf("[Insane payloadLen:%v]\n", payloadLen))
|
|
hc.Close()
|
|
return 1, errors.New("Insane payloadLen")
|
|
}
|
|
|
|
var payloadBytes = make([]byte, payloadLen)
|
|
n, err = io.ReadFull(*hc.c, payloadBytes)
|
|
|
|
// Normal client 'exit' from interactive session will cause
|
|
// (on server side) err.Error() == "<iface/addr info ...>: use of closed network connection"
|
|
if err != nil && err.Error() != "EOF" {
|
|
if !strings.HasSuffix(err.Error(), "use of closed network connection") {
|
|
Log.Err(fmt.Sprintln("[3]unexpected Read() err:", err))
|
|
} else {
|
|
Log.Notice(fmt.Sprintln("[Client hung up]"))
|
|
}
|
|
}
|
|
|
|
log.Printf(" <:ctext:\r\n%s\r\n", hex.Dump(payloadBytes[:n]))
|
|
|
|
db := bytes.NewBuffer(payloadBytes[:n]) //copying payloadBytes to db
|
|
// The StreamReader acts like a pipe, decrypting
|
|
// whatever is available and forwarding the result
|
|
// to the parameter of Read() as a normal io.Reader
|
|
rs := &cipher.StreamReader{S: hc.r, R: db}
|
|
// The caller isn't necessarily reading the full payload so we need
|
|
// to decrypt to an intermediate buffer, draining it on demand of caller
|
|
decryptN, err := rs.Read(payloadBytes)
|
|
log.Printf(" <-ptext:\r\n%s\r\n", hex.Dump(payloadBytes[:n]))
|
|
if err != nil {
|
|
log.Println("hkexnet.Read():", err)
|
|
//panic(err)
|
|
} else {
|
|
hc.rm.Write(payloadBytes) // Calc hmac on received data
|
|
// Padding: Read padSide, padLen, (padding | d) or (d | padding)
|
|
padSide := payloadBytes[0]
|
|
padLen := payloadBytes[1]
|
|
|
|
payloadBytes = payloadBytes[2:]
|
|
if padSide == 0 {
|
|
payloadBytes = payloadBytes[padLen:]
|
|
} else {
|
|
payloadBytes = payloadBytes[0 : len(payloadBytes)-int(padLen)]
|
|
}
|
|
|
|
//fmt.Printf("padSide:%d padLen:%d payloadBytes:%s\n",
|
|
// padSide, padLen, hex.Dump(payloadBytes))
|
|
|
|
// Throw away pkt if it's chaff (ie., caller to Read() won't see this data)
|
|
if ctrlStatOp == CSOChaff {
|
|
log.Printf("[Chaff pkt, discarded (len %d)]\n", decryptN)
|
|
} else if ctrlStatOp == CSOTermSize {
|
|
fmt.Sscanf(string(payloadBytes), "%d %d", &hc.Rows, &hc.Cols)
|
|
log.Printf("[TermSize pkt: rows %v cols %v]\n", hc.Rows, hc.Cols)
|
|
hc.WinCh <- WinSize{hc.Rows, hc.Cols}
|
|
} else if ctrlStatOp == CSOExitStatus {
|
|
if len(payloadBytes) > 0 {
|
|
hc.SetStatus(CSOType(binary.BigEndian.Uint32(payloadBytes)))
|
|
} else {
|
|
Log.Err(fmt.Sprintln("[truncated payload, cannot determine CSOExitStatus]"))
|
|
hc.SetStatus(CSETruncCSO)
|
|
}
|
|
hc.Close()
|
|
} else {
|
|
hc.dBuf.Write(payloadBytes)
|
|
//log.Printf("hc.dBuf: %s\n", hex.Dump(hc.dBuf.Bytes()))
|
|
}
|
|
|
|
hTmp := hc.rm.Sum(nil)[0:HMAC_CHK_SZ]
|
|
log.Printf("<%04x) HMAC:(i)%s (c)%02x\r\n", decryptN, hex.EncodeToString([]byte(hmacIn[0:])), hTmp)
|
|
|
|
if *hc.closeStat == CSETruncCSO {
|
|
Log.Err(fmt.Sprintln("[cannot verify HMAC]"))
|
|
} else {
|
|
// Log alert if hmac didn't match, corrupted channel
|
|
if !bytes.Equal(hTmp, []byte(hmacIn[0:])) /*|| hmacIn[0] > 0xf8*/ {
|
|
Log.Err(fmt.Sprintln("** ALERT - detected HMAC mismatch, possible channel tampering **"))
|
|
_, _ = (*hc.c).Write([]byte{CSOHmacInvalid})
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
retN := hc.dBuf.Len()
|
|
if retN > len(b) {
|
|
retN = len(b)
|
|
}
|
|
|
|
log.Printf("Read() got %d bytes\n", retN)
|
|
copy(b, hc.dBuf.Next(retN))
|
|
return retN, nil
|
|
}
|
|
|
|
// Write a byte slice
|
|
//
|
|
// See go doc io.Writer
|
|
func (hc Conn) Write(b []byte) (n int, err error) {
|
|
//fmt.Printf("WRITE(%d)\n", len(b))
|
|
n, err = hc.WritePacket(b, CSONone)
|
|
//fmt.Printf("WROTE(%d)\n", n)
|
|
return n, err
|
|
}
|
|
|
|
// Write a byte slice with specified ctrlStatusOp byte
|
|
func (hc *Conn) WritePacket(b []byte, op byte) (n int, err error) {
|
|
//log.Printf("[Encrypting...]\r\n")
|
|
var hmacOut []uint8
|
|
var payloadLen uint32
|
|
|
|
if hc.m == nil || hc.wm == nil {
|
|
return 0, errors.New("Secure chan not ready for writing")
|
|
}
|
|
|
|
//Padding
|
|
padSz := (rand.Intn(PAD_SZ) / 2) + (PAD_SZ / 2)
|
|
padLen := padSz - ((len(b) + padSz) % padSz)
|
|
if padLen == padSz {
|
|
// No padding required
|
|
padLen = 0
|
|
}
|
|
padBytes := make([]byte, padLen)
|
|
rand.Read(padBytes)
|
|
// For a little more confusion let's support padding either before
|
|
// or after the payload.
|
|
padSide := rand.Intn(2)
|
|
//fmt.Printf("--\n")
|
|
//fmt.Printf("PRE_PADDING:%s\r\n", hex.Dump(b))
|
|
//fmt.Printf("padSide:%d padLen:%d\r\n", padSide, padLen)
|
|
if padSide == 0 {
|
|
b = append([]byte{byte(padSide)}, append([]byte{byte(padLen)}, append(padBytes, b...)...)...)
|
|
} else {
|
|
b = append([]byte{byte(padSide)}, append([]byte{byte(padLen)}, append(b, padBytes...)...)...)
|
|
}
|
|
//fmt.Printf("POST_PADDING:%s\r\n", hex.Dump(b))
|
|
//fmt.Printf("--\r\n")
|
|
|
|
// N.B. Originally this Lock() surrounded only the
|
|
// calls to binary.Write(hc.c ..) however there appears
|
|
// to be some other unshareable state in the Conn
|
|
// struct that must be protected to serialize main and
|
|
// chaff data written to it.
|
|
//
|
|
// Would be nice to determine if the mutex scope
|
|
// could be tightened.
|
|
hc.m.Lock()
|
|
payloadLen = uint32(len(b))
|
|
//!fmt.Printf(" --== payloadLen:%d\n", payloadLen)
|
|
log.Printf(" :>ptext:\r\n%s\r\n", hex.Dump(b[0:payloadLen]))
|
|
|
|
// Calculate hmac on payload
|
|
hc.wm.Write(b[0:payloadLen])
|
|
hmacOut = hc.wm.Sum(nil)[0:HMAC_CHK_SZ]
|
|
|
|
log.Printf(" (%04x> HMAC(o):%s\r\n", payloadLen, hex.EncodeToString(hmacOut))
|
|
|
|
var wb bytes.Buffer
|
|
// The StreamWriter acts like a pipe, forwarding whatever is
|
|
// written to it through the cipher, encrypting as it goes
|
|
ws := &cipher.StreamWriter{S: hc.w, W: &wb}
|
|
_, err = ws.Write(b[0:payloadLen])
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
log.Printf(" ->ctext:\r\n%s\r\n", hex.Dump(wb.Bytes()))
|
|
|
|
ctrlStatOp := op
|
|
err = binary.Write(*hc.c, binary.BigEndian, &ctrlStatOp)
|
|
if err == nil {
|
|
// Write hmac LSB, payloadLen followed by payload
|
|
err = binary.Write(*hc.c, binary.BigEndian, hmacOut)
|
|
if err == nil {
|
|
err = binary.Write(*hc.c, binary.BigEndian, payloadLen)
|
|
if err == nil {
|
|
n, err = (*hc.c).Write(wb.Bytes())
|
|
} else {
|
|
//fmt.Println("[c]WriteError!")
|
|
}
|
|
} else {
|
|
//fmt.Println("[b]WriteError!")
|
|
}
|
|
} else {
|
|
//fmt.Println("[a]WriteError!")
|
|
}
|
|
hc.m.Unlock()
|
|
|
|
if err != nil {
|
|
log.Println(err)
|
|
}
|
|
|
|
// We must 'lie' to caller indicating the length of THEIR
|
|
// data written (ie., not including the padding and padding headers)
|
|
return n - 2 - int(padLen), err
|
|
}
|
|
|
|
func (hc *Conn) EnableChaff() {
|
|
hc.chaff.shutdown = false
|
|
hc.chaff.enabled = true
|
|
log.Println("Chaffing ENABLED")
|
|
hc.chaffHelper()
|
|
}
|
|
|
|
func (hc *Conn) DisableChaff() {
|
|
hc.chaff.enabled = false
|
|
log.Println("Chaffing DISABLED")
|
|
}
|
|
|
|
func (hc *Conn) ShutdownChaff() {
|
|
hc.chaff.shutdown = true
|
|
log.Println("Chaffing SHUTDOWN")
|
|
}
|
|
|
|
func (hc *Conn) SetupChaff(msecsMin uint, msecsMax uint, szMax uint) {
|
|
hc.chaff.msecsMin = msecsMin //move these to params of chaffHelper() ?
|
|
hc.chaff.msecsMax = msecsMax
|
|
hc.chaff.szMax = szMax
|
|
}
|
|
|
|
// Helper routine to spawn a chaffing goroutine for each Conn
|
|
func (hc *Conn) chaffHelper() {
|
|
go func() {
|
|
for {
|
|
var nextDuration int
|
|
if hc.chaff.enabled {
|
|
var bufTmp []byte
|
|
bufTmp = make([]byte, rand.Intn(int(hc.chaff.szMax)))
|
|
min := int(hc.chaff.msecsMin)
|
|
nextDuration = rand.Intn(int(hc.chaff.msecsMax)-min) + min
|
|
_, _ = rand.Read(bufTmp)
|
|
_, err := hc.WritePacket(bufTmp, CSOChaff)
|
|
if err != nil {
|
|
log.Println("[ *** error - chaffHelper quitting *** ]")
|
|
hc.chaff.enabled = false
|
|
break
|
|
}
|
|
}
|
|
time.Sleep(time.Duration(nextDuration) * time.Millisecond)
|
|
if hc.chaff.shutdown {
|
|
log.Println("*** chaffHelper shutting down")
|
|
break
|
|
}
|
|
|
|
}
|
|
}()
|
|
}
|