From 6250f0b93c5c4cb7d4df074813d510e59100eaaea1afea45a0409dc8798c482c Mon Sep 17 00:00:00 2001 From: Sergey Matveev Date: Wed, 18 Oct 2023 22:50:00 +0300 Subject: [PATCH] v2 --- COPYING | 674 +++++++++++++++++++++++++++++++++++++++++++++++ INSTALL | 1 + PROTOCOL | 48 ++-- README | 34 +-- USAGE | 22 ++ build | 5 + cmd/init/main.go | 291 ++++++++++++++++++++ cmd/resp/main.go | 258 ++++++++++++++++++ crypto.go | 138 ++++++++++ go.mod | 12 +- go.sum | 9 +- main.go | 307 --------------------- utils.go | 53 ++++ x509.go | 103 ++++++++ 14 files changed, 1596 insertions(+), 359 deletions(-) create mode 100644 COPYING create mode 100644 INSTALL create mode 100644 USAGE create mode 100755 build create mode 100644 cmd/init/main.go create mode 100644 cmd/resp/main.go create mode 100644 crypto.go delete mode 100644 main.go create mode 100644 utils.go create mode 100644 x509.go diff --git a/COPYING b/COPYING new file mode 100644 index 0000000..58f2b48 --- /dev/null +++ b/COPYING @@ -0,0 +1,674 @@ + GNU GENERAL PUBLIC LICENSE + Version 3, 29 June 2007 + + Copyright (C) 2007 Free Software Foundation, Inc. + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. + + Preamble + + The GNU General Public License is a free, copyleft license for +software and other kinds of works. + + The licenses for most software and other practical works are designed +to take away your freedom to share and change the works. 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If not, see . + +Also add information on how to contact you by electronic and paper mail. + + If the program does terminal interaction, make it output a short +notice like this when it starts in an interactive mode: + + Copyright (C) + This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. + This is free software, and you are welcome to redistribute it + under certain conditions; type `show c' for details. + +The hypothetical commands `show w' and `show c' should show the appropriate +parts of the General Public License. Of course, your program's commands +might be different; for a GUI interface, you would use an "about box". + + You should also get your employer (if you work as a programmer) or school, +if any, to sign a "copyright disclaimer" for the program, if necessary. +For more information on this, and how to apply and follow the GNU GPL, see +. + + The GNU General Public License does not permit incorporating your program +into proprietary programs. If your program is a subroutine library, you +may consider it more useful to permit linking proprietary applications with +the library. If this is what you want to do, use the GNU Lesser General +Public License instead of this License. But first, please read +. diff --git a/INSTALL b/INSTALL new file mode 100644 index 0000000..6178352 --- /dev/null +++ b/INSTALL @@ -0,0 +1 @@ +Compile udpobfs-init and udpobfs-resp commands with ./build diff --git a/PROTOCOL b/PROTOCOL index 257eacd..fe2574f 100644 --- a/PROTOCOL +++ b/PROTOCOL @@ -1,29 +1,27 @@ -Protocol is trivial. Both peers have shared 256-bit key. -SHA3 is used to derive four more keys from it: +After TLS 1.3 handshake is finished, 512-bit keying material is +exported. Various 256-bit keys are derived from it: - SHAKE128("go.cypherpunks.ru/udpobfs" || key) -> - 256-bit InitiatorEncryptionKey || - 256-bit InitiatorObfuscationKey || - 256-bit ResponderEncryptionKey || - 256-bit ResponderObfuscationKey + InitEncKey = BLAKE3-DeriveKey(seed, "go.cypherpunks.ru/udpobfs/v2 init enc") + InitMACKey = BLAKE3-DeriveKey(seed, "go.cypherpunks.ru/udpobfs/v2 init mac") + InitObfsKey = BLAKE3-DeriveKey(seed, "go.cypherpunks.ru/udpobfs/v2 init obfs") + RespEncKey = BLAKE3-DeriveKey(seed, "go.cypherpunks.ru/udpobfs/v2 resp enc") + RespMACKey = BLAKE3-DeriveKey(seed, "go.cypherpunks.ru/udpobfs/v2 resp mac") + RespObfsKey = BLAKE3-DeriveKey(seed, "go.cypherpunks.ru/udpobfs/v2 resp obfs") -Each side has big-endian 64-bit packet number counter, that is used as a -nonce. That counter is kept in memory and only its lower 24 bits are -sent. When remote side receives 24-bit counter with lower value, then it -increments in-memory counter's remaining part. Completely the same as -Extended Sequence Numbers are done in IPsec's ESP. +Each peer has 64-bit packet sequence counter. It is fed to +BLAKE3(len=256, key=*EncKey) and then its XOF output is XORed with +plaintext packet. Then BLAKE3(len=48, key=*MACKey) is taken over the +sequence counter concatenated with the ciphertext. That MAC, lower +16-bits of the sequence counter are encrypted with Blowfish(key=*ObfsKey) +and prepended to the ciphertext. -ChaCha20 is initialised with corresponding EncryptionKey and nonce equal -to the full sequence number value. Its first 256-bit of output will be -Poly1305's one-time key. Next 256-bits are ignored. Further ones are -XORed with the plaintext (UDP's payload). Poly1305 is calculated over -the full 64-bit sequence number value and the whole ciphertext. Higher -40-bits of the resulting tag with lower 24-bits of the sequence number -are prepended to the ciphertext, encrypted with Blowfish: + ciphertext = BLAKE3(len=256, key=*EncKey)(SeqNum).XOF(len=len(plaintext)) + ciphertext = ciphertext XOR plaintext + mac = BLAKE3(len=48, key=*MACKey)(SeqNum || ciphertext) + send(Blowfish(key=*ObfsKey)(mac || SeqNum[6:]) || ciphertext) - Blowfish(Seq || MAC) || Ciphertext - -Blowfish is initialized with ObfuscationKey. 40-bit MAC is rather weak, -but enough for obfuscation purposes. 24-bit part of sequence number is -enough for medium data-rate transmission where reordering or packets -drops may occur. +All of that gives only 8-byte overhead, providing at least some 48-bit +authentication and invisibility of cleartext nonces/sequences. BLAKE3 is +pretty fast algorithm, however ChaCha20-Poly1305 can be faster for small +messages -- so performance depends on message sizes. Blowfish is just +the fastest (serious) cipher with 64-bit blocksize in the Go's library. diff --git a/README b/README index 94dcb52..39018a8 100644 --- a/README +++ b/README @@ -1,30 +1,20 @@ udpobfs -- simple point-to-point UDP obfuscation proxy This is trivial UDP proxy, that obfuscates UDP traffic between two UDP -ports. It does no handshaking, no key agreement, no peer authentication, -weak replay protection. Key setup/renew must be made for example through -OpenSSH, TLS or similar channels. udpobfs's purpose is to obfuscate UDP -traffic between two WireGuard peers with minimal CPU and traffic overhead. +ports. Aimed to generate fully pseudorandom traffic indistinguishable +from the noise from the point of the third party observer. -Assume that WG was running peered with [2001:db8::dc]:1194. -You can run two udpobfs instances to obfuscate traffic between them: +It initiates TLS 1.3 connection between the peers to mutually +authenticate them and agree on shared keying material. After that it +passes traffic on the same port numbers for UDP. There could be multiple +simultaneous sessions alive. - # udpobfs -keygen > key.txt - - wg0# wg set endpoint [::1]:4911 - wg0# udpobfs -bind [::1]:4911 -dst [2001:db8::ac]:1194 < key.txt - - wg1# wg set listen-port 21194 - wg1# udpobfs -bind [2001:db8::ac]:1194 -dst [::1]:21194 -responder < key.txt - -One of the instances is responder -- it awaits when initiator starts -talking. If UDP binded connection is lost, daemon exits. So it is -advisable to run it under process supervisor. - -udpobfs continuously reads Base32-encoded 256-bit keys from stdin -- you -can renew them without restarting the daemons. Of course there is some -time window when key knowledge differs on both peers and they will loose -the traffic. Not a big deal. +It assures that at least single packet is passed on ten second +intervals. If no (real) traffic is passed for two minutes, then +connections (both TCP and UDP) are closed. Every minute ping/pong +occurs over the TLS channel to keep it alive. Obfuscated packet is 8 bytes longer, so you have to slightly lower your MTU in VPN tunnel. + +udpobfs is free software: see the file COPYING for copying conditions. diff --git a/USAGE b/USAGE new file mode 100644 index 0000000..070a6b9 --- /dev/null +++ b/USAGE @@ -0,0 +1,22 @@ +Prepare X.509 keypair for both server and client, with CA certificate +able to authenticate both peers. For example with zeasypki +(http://www.git.stargrave.org/?p=zeasypki.git;a=blob;f=README): + + $ zeasypki ca eddsa udpobfs-ca + $ zeasypki new ee/eddsa/udpobfs-ca/server-name + $ zeasypki new ee/eddsa/udpobfs-ca/client + $ zeasypki keypair ee/eddsa/udpobfs-ca/server-name > server.pem + $ zeasypki keypair ee/eddsa/udpobfs-ca/client > client.pem + $ cp ca/eddsa/udpobfs-ca/cer.pem ca.pem + $ zeasypki dane ee/eddsa/udpobfs-ca/server-name > server.hash + +Assume that WireGuard was running peered with [2001:db8::dc]:1194. +Run udpobfs instances to obfuscate traffic between them: + + wg0# wg set endpoint [::1]:4911 + wg0# udpobfs-init -bind [::1]:4911 -dst [2001:db8::ac]:1194 \ + -ca ca.pem -keypair client.pem -name server-name -hash `cat server.hash` + + wg1# wg set listen-port 21194 + wg1# udpobfs-resp -bind [2001:db8::ac]:1194 -dst [::1]:21194 \ + -ca ca.pem -keypair server.pem diff --git a/build b/build new file mode 100755 index 0000000..9fc8341 --- /dev/null +++ b/build @@ -0,0 +1,5 @@ +#!/bin/sh -e + +for cmd in init resp ; do + go build -C cmd/$cmd -o ../../udpobfs-$cmd -ldflags=-s +done diff --git a/cmd/init/main.go b/cmd/init/main.go new file mode 100644 index 0000000..77b8213 --- /dev/null +++ b/cmd/init/main.go @@ -0,0 +1,291 @@ +/* +udpobfs -- simple point-to-point UDP obfuscation proxy +Copyright (C) 2023 Sergey Matveev + +This program is free software: you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation, version 3 of the License. + +This program is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with this program. If not, see . +*/ + +package main + +import ( + "bytes" + "crypto/rand" + "crypto/sha256" + "crypto/tls" + "crypto/x509" + "encoding/hex" + "errors" + "flag" + "io" + "log" + "log/slog" + "net" + "os" + "sync" + "time" + + "go.cypherpunks.ru/udpobfs/v2" + "lukechampine.com/blake3" +) + +var ( + DstAddrUDP *net.UDPAddr + DstAddrTCP *net.TCPAddr + TLSConfig *tls.Config + LnUDP *net.UDPConn + Peers = make(map[string]chan udpobfs.Buf) + Bufs = sync.Pool{New: func() any { return new([udpobfs.BufLen]byte) }} +) + +func newPeer(localAddr net.Addr, dataInitial []byte) { + logger := slog.With("remote", localAddr.String()) + logger.Info("connected") + conn, err := net.DialTCP("tcp", nil, DstAddrTCP) + if err != nil { + slog.Warn(err.Error()) + return + } + defer conn.Close() + srcAddr, err := net.ResolveUDPAddr("udp", conn.LocalAddr().String()) + if err != nil { + log.Fatal(err) + } + logger = logger.With("local", srcAddr.String()) + connTLS := tls.Client(conn, TLSConfig) + err = connTLS.Handshake() + if err != nil { + logger.Error(err.Error()) + return + } + defer connTLS.Close() + tlsState := connTLS.ConnectionState() + logger = logger.With("cn", tlsState.PeerCertificates[0].Subject.CommonName) + logger.Info("authenticated") + seed, err := tlsState.ExportKeyingMaterial(udpobfs.App, nil, udpobfs.SeedLen) + if err != nil { + logger.Error(err.Error()) + return + } + connUDP, err := net.ListenUDP("udp", srcAddr) + if err != nil { + logger.Error(err.Error()) + return + } + cryptoState := udpobfs.NewCryptoState(seed, true) + txs := make(chan udpobfs.Buf) + rxFinished := make(chan struct{}) + var rxPkts, txPkts, rxBytes, txBytes int64 + go func() { + var n int + var err error + rx := make([]byte, udpobfs.BufLen) + tx := make([]byte, udpobfs.BufLen) + var got []byte + for { + connUDP.SetReadDeadline(time.Now().Add(2 * udpobfs.LifetimeDuration)) + n, err = connUDP.Read(rx) + if n == 0 { + if err != nil { + break + } + continue + } + if n < udpobfs.SeqLen { + logger.Warn("too short") + continue + } + got = cryptoState.Rx(tx[:n], rx[:n]) + if got == nil { + logger.Warn("bad MAC") + continue + } + if len(got) != 0 { + rxPkts++ + rxBytes += int64(len(got)) + LnUDP.WriteTo(got, localAddr) + } + if err != nil { + break + } + } + close(rxFinished) + }() + go func() { + buf := make([]byte, udpobfs.BufLen) + var tx udpobfs.Buf + ticker := time.NewTicker(udpobfs.PingDuration) + defer ticker.Stop() + now := time.Now() + lastPing := now + last := now + var got []byte + for { + select { + case <-ticker.C: + now = time.Now() + if now.Sub(last) > 2*udpobfs.LifetimeDuration { + connUDP.Close() + return + } + if now.Sub(lastPing) > udpobfs.PingDuration { + _, err = connUDP.WriteTo( + cryptoState.Tx(buf[:udpobfs.SeqLen], nil), DstAddrUDP) + lastPing = now + } + case tx = <-txs: + if tx.Buf == nil { + return + } + got = cryptoState.Tx(buf[:udpobfs.SeqLen+tx.N], (*tx.Buf)[:tx.N]) + Bufs.Put(tx.Buf) + connUDP.WriteTo(got, DstAddrUDP) + txPkts++ + txBytes += int64(len(got)) + lastPing = time.Now() + last = lastPing + } + } + }() + Peers[localAddr.String()] = txs + { + txPkts++ + txBytes += int64(len(dataInitial)) + tmp := make([]byte, udpobfs.SeqLen+len(dataInitial)) + connUDP.WriteTo(cryptoState.Tx(tmp, dataInitial), DstAddrUDP) + } + go func() { + defer connUDP.Close() + ticker := time.NewTicker(udpobfs.LifetimeDuration) + defer ticker.Stop() + our := make([]byte, 8) + their := make([]byte, 8) + key := make([]byte, 32) + if _, err = io.ReadFull(rand.Reader, key); err != nil { + log.Fatal(err) + } + rnd := blake3.New(32, key).XOF() + var err error + for { + select { + case <-ticker.C: + if _, err = io.ReadFull(rnd, our); err != nil { + log.Fatal(err) + } + if _, err = connTLS.Write(our); err != nil { + return + } + if _, err = io.ReadFull(connTLS, their); err != nil { + return + } + if !bytes.Equal(our, their) { + logger.Error("pong mismatch") + return + } + case <-rxFinished: + return + } + } + }() + <-rxFinished + logger.Info("finishing", + "rxPkts", rxPkts, + "rxBytes", rxBytes, + "txPkts", txPkts, + "txBytes", txBytes) + delete(Peers, localAddr.String()) + txs <- udpobfs.Buf{Buf: nil} + go func() { + for range txs { + } + }() +} + +func main() { + bind := flag.String("bind", "[::]:1194", "Address to bind to") + dst := flag.String("dst", "[2001:db8::1234]:1194", "Address to connect to") + keypairPath := flag.String("keypair", "keypair.pem", "X.509 keypair") + caPath := flag.String("ca", "ca.pem", "CA certificate") + serverHash := flag.String("hash", "", "Expected server's SPKI SHA256 fingerprint") + serverName := flag.String("name", "example.com", "Expected server's hostname") + flag.Parse() + log.SetFlags(log.Lshortfile) + slog.SetDefault(slog.New(slog.NewTextHandler(os.Stderr, nil))) + + crtRaw, _, err := udpobfs.CertificateFromFile(*keypairPath) + if err != nil { + log.Fatal(err) + } + prv, err := udpobfs.PrivateKeyFromFile(*keypairPath) + if err != nil { + log.Fatal(err) + } + TLSConfig = &tls.Config{ + MinVersion: tls.VersionTLS13, + Certificates: []tls.Certificate{{ + Certificate: [][]byte{crtRaw}, + PrivateKey: prv, + }}, + ServerName: *serverName, + } + _, TLSConfig.RootCAs, err = udpobfs.CertPoolFromFile(*caPath) + if err != nil { + log.Fatalln(err) + } + + if *serverHash != "" { + hshOur, err := hex.DecodeString(*serverHash) + if err != nil { + log.Fatal(err) + } + TLSConfig.VerifyPeerCertificate = func( + rawCerts [][]byte, + verifiedChains [][]*x509.Certificate, + ) error { + spki := verifiedChains[0][0].RawSubjectPublicKeyInfo + hshTheir := sha256.Sum256(spki) + if !bytes.Equal(hshOur, hshTheir[:]) { + return errors.New("server certificate's SPKI hash mismatch") + } + return nil + } + } + + DstAddrUDP = udpobfs.MustResolveUDPAddr(*dst) + DstAddrTCP = udpobfs.MustResolveTCPAddr(*dst) + LnUDP, err = net.ListenUDP("udp", udpobfs.MustResolveUDPAddr(*bind)) + if err != nil { + log.Fatal(err) + } + + var n int + var from net.Addr + var txs chan udpobfs.Buf + var buf *[udpobfs.BufLen]byte + for { + buf = Bufs.Get().(*[udpobfs.BufLen]byte) + n, from, _ = LnUDP.ReadFrom((*buf)[:]) + if n == 0 { + continue + } + txs = Peers[from.String()] + if txs != nil { + txs <- udpobfs.Buf{Buf: buf, N: n} + } + if txs == nil { + neu := make([]byte, n) + copy(neu, (*buf)[:n]) + Bufs.Put(buf) + go newPeer(from, neu) + } + } +} diff --git a/cmd/resp/main.go b/cmd/resp/main.go new file mode 100644 index 0000000..cc97336 --- /dev/null +++ b/cmd/resp/main.go @@ -0,0 +1,258 @@ +/* +udpobfs -- simple point-to-point UDP obfuscation proxy +Copyright (C) 2023 Sergey Matveev + +This program is free software: you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation, version 3 of the License. + +This program is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with this program. If not, see . +*/ + +package main + +import ( + "crypto/tls" + "flag" + "io" + "log" + "log/slog" + "net" + "os" + "sync" + "time" + + "go.cypherpunks.ru/udpobfs/v2" +) + +var ( + DstAddrUDP *net.UDPAddr + TLSConfig *tls.Config + LnUDP *net.UDPConn + LnTCP *net.TCPListener + Peers = make(map[string]chan udpobfs.Buf) + Bufs = sync.Pool{New: func() any { return new([udpobfs.BufLen]byte) }} +) + +func newPeer(conn net.Conn) { + logger := slog.With("remote", conn.RemoteAddr().String()) + logger.Info("connected") + defer conn.Close() + remoteAddr := udpobfs.MustResolveUDPAddr(conn.RemoteAddr().String()) + localUDP, err := net.DialUDP("udp", nil, DstAddrUDP) + if err != nil { + log.Fatal(err) + } + logger = logger.With("local", localUDP.LocalAddr().String()) + connTLS := tls.Server(conn, TLSConfig) + err = connTLS.Handshake() + if err != nil { + logger.Error(err.Error()) + return + } + defer connTLS.Close() + tlsState := connTLS.ConnectionState() + logger = logger.With("cn", tlsState.PeerCertificates[0].Subject.CommonName) + logger.Info("authenticated") + seed, err := tlsState.ExportKeyingMaterial(udpobfs.App, nil, udpobfs.SeedLen) + if err != nil { + logger.Error(err.Error()) + return + } + cryptoState := udpobfs.NewCryptoState(seed, false) + txs := make(chan udpobfs.Buf) + txFinished := make(chan struct{}) + var rxPkts, txPkts, rxBytes, txBytes int64 + go func() { + pkts := make(chan []byte) + pktRead := make(chan struct{}) + go func() { + var n int + var err error + rx := make([]byte, udpobfs.BufLen) + for { + localUDP.SetReadDeadline(time.Now().Add(time.Minute)) + n, err = localUDP.Read(rx) + if n != 0 { + pkts <- rx[:n] + <-pktRead + } + if err != nil { + break + } + } + close(pkts) + }() + ticker := time.NewTicker(udpobfs.PingDuration) + defer ticker.Stop() + var pkt []byte + var ok bool + tx := make([]byte, udpobfs.BufLen) + now := time.Now() + lastPing := now + var got []byte + for { + select { + case <-ticker.C: + now = time.Now() + if now.Sub(lastPing) > udpobfs.PingDuration { + LnUDP.WriteTo( + cryptoState.Tx(tx[:udpobfs.SeqLen], nil), remoteAddr) + lastPing = now + } + case pkt, ok = <-pkts: + if !ok { + close(txFinished) + return + } + got = cryptoState.Tx(tx[:udpobfs.SeqLen+len(pkt)], pkt) + pktRead <- struct{}{} + LnUDP.WriteTo(got, remoteAddr) + txPkts++ + txBytes += int64(len(pkt)) + lastPing = time.Now() + } + } + }() + go func() { + ticker := time.NewTicker(2 * udpobfs.LifetimeDuration) + defer ticker.Stop() + now := time.Now() + last := now + buf := make([]byte, udpobfs.BufLen) + var tx udpobfs.Buf + var got []byte + for { + select { + case <-txFinished: + return + case <-ticker.C: + now = time.Now() + if now.Sub(last) > 2*udpobfs.LifetimeDuration { + localUDP.Close() + return + } + case tx = <-txs: + if tx.Buf == nil { + break + } + if tx.N < udpobfs.SeqLen { + logger.Warn("too short") + Bufs.Put(tx.Buf) + continue + } + got = cryptoState.Rx(buf[:tx.N], (*tx.Buf)[:tx.N]) + Bufs.Put(tx.Buf) + if got == nil { + logger.Warn("bad MAC") + continue + } + if len(got) != 0 { + rxPkts++ + rxBytes += int64(len(got)) + localUDP.Write(got) + } + last = time.Now() + } + } + }() + Peers[remoteAddr.String()] = txs + go func() { + buf := make([]byte, 8) + for { + connTLS.SetReadDeadline(time.Now().Add(2 * udpobfs.LifetimeDuration)) + if _, err = io.ReadFull(connTLS, buf); err != nil { + break + } + if _, err = connTLS.Write(buf); err != nil { + break + } + } + }() + <-txFinished + logger.Info("finishing", + "rxPkts", rxPkts, + "rxBytes", rxBytes, + "txPkts", txPkts, + "txBytes", txBytes) + delete(Peers, remoteAddr.String()) + txs <- udpobfs.Buf{Buf: nil} + go func() { + for range txs { + } + }() +} + +func main() { + bind := flag.String("bind", "[::]:1194", "Address to bind to") + dst := flag.String("dst", "[2001:db8::1234]:1194", "Address to connect to") + keypairPath := flag.String("keypair", "keypair.pem", "X.509 keypair") + caPath := flag.String("ca", "ca.pem", "CA certificate") + flag.Parse() + log.SetFlags(log.Lshortfile) + slog.SetDefault(slog.New(slog.NewTextHandler(os.Stderr, nil))) + + crtRaw, _, err := udpobfs.CertificateFromFile(*keypairPath) + if err != nil { + log.Fatal(err) + } + prv, err := udpobfs.PrivateKeyFromFile(*keypairPath) + if err != nil { + log.Fatal(err) + } + TLSConfig = &tls.Config{ + MinVersion: tls.VersionTLS13, + ClientAuth: tls.RequireAndVerifyClientCert, + Certificates: []tls.Certificate{{ + Certificate: [][]byte{crtRaw}, + PrivateKey: prv, + }}, + } + _, TLSConfig.ClientCAs, err = udpobfs.CertPoolFromFile(*caPath) + if err != nil { + log.Fatalln(err) + } + + DstAddrUDP = udpobfs.MustResolveUDPAddr(*dst) + LnUDP, err = net.ListenUDP("udp", udpobfs.MustResolveUDPAddr(*bind)) + if err != nil { + log.Fatal(err) + } + LnTCP, err = net.ListenTCP("tcp", udpobfs.MustResolveTCPAddr(*bind)) + if err != nil { + log.Fatal(err) + } + + go func() { + var n int + var from net.Addr + var txs chan udpobfs.Buf + var buf *[udpobfs.BufLen]byte + for { + buf = Bufs.Get().(*[udpobfs.BufLen]byte) + n, from, _ = LnUDP.ReadFrom((*buf)[:]) + if n == 0 { + continue + } + txs = Peers[from.String()] + if txs != nil { + txs <- udpobfs.Buf{Buf: buf, N: n} + } + } + }() + + for { + conn, err := LnTCP.Accept() + if err != nil { + slog.Error(err.Error()) + continue + } + go newPeer(conn) + } +} diff --git a/crypto.go b/crypto.go new file mode 100644 index 0000000..0905689 --- /dev/null +++ b/crypto.go @@ -0,0 +1,138 @@ +/* +udpobfs -- simple point-to-point UDP obfuscation proxy +Copyright (C) 2023 Sergey Matveev + +This program is free software: you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation, version 3 of the License. + +This program is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with this program. If not, see . +*/ + +package udpobfs + +import ( + "crypto/subtle" + "io" + "log" + + "golang.org/x/crypto/blowfish" + "lukechampine.com/blake3" +) + +const ( + App = "go.cypherpunks.ru/udpobfs/v2" + MACLen = 6 + SeqLen = 8 + SeedLen = 64 +) + +func MustNewBlowfish(key []byte) *blowfish.Cipher { + ciph, err := blowfish.NewCipher(key) + if err != nil { + log.Fatal(err) + } + return ciph +} + +type CryptoState struct { + rxEnc, rxMAC *blake3.Hasher + txEnc, txMAC *blake3.Hasher + rxObfs, txObfs *blowfish.Cipher + rxSeq, txSeq [SeqLen]byte +} + +func NewCryptoState(seed []byte, isInit bool) *CryptoState { + var hInitEncKey, hInitMACKey [32]byte + var hRespEncKey, hRespMACKey [32]byte + var obfsInitKey, obfsRespKey [32]byte + blake3.DeriveKey(hInitEncKey[:], App+" init enc", seed) + blake3.DeriveKey(hInitMACKey[:], App+" init mac", seed) + blake3.DeriveKey(hRespEncKey[:], App+" resp enc", seed) + blake3.DeriveKey(hRespMACKey[:], App+" resp mac", seed) + blake3.DeriveKey(obfsInitKey[:], App+" init obfs", seed) + blake3.DeriveKey(obfsRespKey[:], App+" resp obfs", seed) + hInitEnc := blake3.New(32, hInitEncKey[:]) + hInitMAC := blake3.New(MACLen, hInitMACKey[:]) + hRespEnc := blake3.New(32, hRespEncKey[:]) + hRespMAC := blake3.New(MACLen, hRespMACKey[:]) + obfsInit := MustNewBlowfish(obfsInitKey[:]) + obfsResp := MustNewBlowfish(obfsRespKey[:]) + state := CryptoState{} + if isInit { + state.rxEnc = hRespEnc + state.rxMAC = hRespMAC + state.rxObfs = obfsResp + state.txEnc = hInitEnc + state.txMAC = hInitMAC + state.txObfs = obfsInit + } else { + state.rxEnc = hInitEnc + state.rxMAC = hInitMAC + state.rxObfs = obfsInit + state.txEnc = hRespEnc + state.txMAC = hRespMAC + state.txObfs = obfsResp + } + return &state +} + +func (state *CryptoState) Tx(dst, src []byte) []byte { + if len(dst) != SeqLen+len(src) { + log.Fatal("unexpected dst len") + } + if Incr(state.txSeq[MACLen:]) { + Incr(state.txSeq[:MACLen]) + } + copy(dst, state.txSeq[:]) + state.txEnc.Reset() + MustWrite(state.txEnc, state.txSeq[:]) + if _, err := io.ReadFull(state.txEnc.XOF(), dst[SeqLen:]); err != nil { + log.Fatal(err) + } + subtle.XORBytes(dst[SeqLen:], dst[SeqLen:], src) + state.txMAC.Reset() + MustWrite(state.txMAC, dst) + state.txMAC.Sum(dst[:0]) + state.txObfs.Encrypt(dst[:SeqLen], dst[:SeqLen]) + return dst[:len(src)+SeqLen] +} + +func (state *CryptoState) Rx(dst, src []byte) []byte { + if len(dst) != len(src) { + log.Fatal("unexpected dst len") + } + state.rxObfs.Decrypt(dst[:SeqLen], src[:SeqLen]) + var theirMAC [MACLen]byte + copy(theirMAC[:], dst) + copy(dst, state.rxSeq[:MACLen]) + state.rxMAC.Reset() + MustWrite(state.rxMAC, dst[:SeqLen]) + MustWrite(state.rxMAC, src[SeqLen:]) + var ourMAC [MACLen]byte + state.rxMAC.Sum(ourMAC[:0]) + if subtle.ConstantTimeCompare(ourMAC[:], theirMAC[:]) != 1 { + Incr(dst[:MACLen]) + state.rxMAC.Reset() + MustWrite(state.rxMAC, dst[:SeqLen]) + MustWrite(state.rxMAC, src[SeqLen:]) + state.rxMAC.Sum(ourMAC[:0]) + if subtle.ConstantTimeCompare(ourMAC[:], theirMAC[:]) != 1 { + return nil + } + } + copy(state.rxSeq[:], dst) + state.rxEnc.Reset() + MustWrite(state.rxEnc, dst[:SeqLen]) + if _, err := io.ReadFull(state.rxEnc.XOF(), dst); err != nil { + log.Fatal(err) + } + subtle.XORBytes(dst, dst, src[SeqLen:]) + return dst[:len(src)-SeqLen] +} diff --git a/go.mod b/go.mod index 4f795b6..65fd70d 100644 --- a/go.mod +++ b/go.mod @@ -1,7 +1,13 @@ -module go.cypherpunks.ru/udpobfs +module go.cypherpunks.ru/udpobfs/v2 go 1.21 -require golang.org/x/crypto v0.12.0 +require ( + golang.org/x/crypto v0.12.0 + lukechampine.com/blake3 v1.2.1 +) -require golang.org/x/sys v0.11.0 // indirect +require ( + github.com/klauspost/cpuid/v2 v2.2.5 // indirect + golang.org/x/sys v0.13.0 // indirect +) diff --git a/go.sum b/go.sum index 51b556d..6c98117 100644 --- a/go.sum +++ b/go.sum @@ -1,4 +1,9 @@ +github.com/klauspost/cpuid/v2 v2.2.5 h1:0E5MSMDEoAulmXNFquVs//DdoomxaoTY1kUhbc/qbZg= +github.com/klauspost/cpuid/v2 v2.2.5/go.mod h1:Lcz8mBdAVJIBVzewtcLocK12l3Y+JytZYpaMropDUws= golang.org/x/crypto v0.12.0 h1:tFM/ta59kqch6LlvYnPa0yx5a83cL2nHflFhYKvv9Yk= golang.org/x/crypto v0.12.0/go.mod h1:NF0Gs7EO5K4qLn+Ylc+fih8BSTeIjAP05siRnAh98yw= -golang.org/x/sys v0.11.0 h1:eG7RXZHdqOJ1i+0lgLgCpSXAp6M3LYlAo6osgSi0xOM= -golang.org/x/sys v0.11.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg= +golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg= +golang.org/x/sys v0.13.0 h1:Af8nKPmuFypiUBjVoU9V20FiaFXOcuZI21p0ycVYYGE= +golang.org/x/sys v0.13.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg= +lukechampine.com/blake3 v1.2.1 h1:YuqqRuaqsGV71BV/nm9xlI0MKUv4QC54jQnBChWbGnI= +lukechampine.com/blake3 v1.2.1/go.mod h1:0OFRp7fBtAylGVCO40o87sbupkyIGgbpv1+M1k1LM6k= diff --git a/main.go b/main.go deleted file mode 100644 index b4c317e..0000000 --- a/main.go +++ /dev/null @@ -1,307 +0,0 @@ -/* -udpobfs -- simple point-to-point UDP obfuscation proxy -Copyright (C) 2023 Sergey Matveev - -This program is free software: you can redistribute it and/or modify -it under the terms of the GNU General Public License as published by -the Free Software Foundation, version 3 of the License. - -This program is distributed in the hope that it will be useful, -but WITHOUT ANY WARRANTY; without even the implied warranty of -MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -GNU General Public License for more details. - -You should have received a copy of the GNU General Public License -along with this program. If not, see . -*/ - -package main - -import ( - "bufio" - "crypto/rand" - "crypto/subtle" - "encoding/base32" - "flag" - "fmt" - "io" - "log" - "net" - "os" - "os/signal" - "syscall" - - "golang.org/x/crypto/blowfish" - "golang.org/x/crypto/chacha20" - "golang.org/x/crypto/poly1305" - "golang.org/x/crypto/sha3" -) - -const KeyLen = 32 - -func mustWrite(w io.Writer, data []byte) { - if n, err := w.Write(data); err != nil || n != len(data) { - log.Fatal("non full write") - } -} - -func incr(buf []byte) (overflow bool) { - for i := len(buf) - 1; i >= 0; i-- { - buf[i]++ - if buf[i] != 0 { - return - } - } - overflow = true - return -} - -type State struct { - ourKey, theirKey []byte - ourObfs, theirObfs *blowfish.Cipher - ourNonce, theirNonce []byte - ourSeq, theirSeq []byte -} - -var Base32Codec *base32.Encoding = base32.StdEncoding.WithPadding(base32.NoPadding) - -func main() { - keygen := flag.Bool("keygen", false, "Generate random key") - responder := flag.Bool("responder", false, "Are we responder?") - bind := flag.String("bind", "[::]:1194", "Address to bind to") - dst := flag.String("dst", "[2001:db8::1234]::1194", "Address to connect to") - flag.Parse() - log.SetFlags(log.Ldate | log.Lmicroseconds | log.Lshortfile) - - if *keygen { - key := make([]byte, KeyLen) - if _, err := io.ReadFull(rand.Reader, key); err != nil { - log.Fatal(err) - } - fmt.Println(Base32Codec.EncodeToString(key)) - return - } - - var state *State - stateReady := make(chan struct{}) - go func() { - first := true - s := bufio.NewScanner(os.Stdin) - h := sha3.NewShake128() - for s.Scan() { - key, err := Base32Codec.DecodeString(s.Text()) - if err != nil { - log.Fatal(err) - } - if len(key) != KeyLen { - log.Fatal("wrong key length") - } - h.Reset() - mustWrite(h, []byte("go.cypherpunks.ru/udpobfs")) - mustWrite(h, key) - iEncKey := make([]byte, chacha20.KeySize) - iBlkKey := make([]byte, 32) - rEncKey := make([]byte, chacha20.KeySize) - rBlkKey := make([]byte, 32) - if _, err := io.ReadFull(h, iEncKey); err != nil { - log.Fatal(err) - } - if _, err := io.ReadFull(h, iBlkKey); err != nil { - log.Fatal(err) - } - if _, err := io.ReadFull(h, rEncKey); err != nil { - log.Fatal(err) - } - if _, err := io.ReadFull(h, rBlkKey); err != nil { - log.Fatal(err) - } - iObfs, err := blowfish.NewCipher(iBlkKey) - if err != nil { - log.Fatal(err) - } - rObfs, err := blowfish.NewCipher(rBlkKey) - if err != nil { - log.Fatal(err) - } - var newState State - if *responder { - newState = State{ - ourKey: rEncKey, - theirKey: iEncKey, - ourObfs: rObfs, - theirObfs: iObfs, - ourNonce: make([]byte, chacha20.NonceSize), - theirNonce: make([]byte, chacha20.NonceSize), - } - } else { - newState = State{ - ourKey: iEncKey, - theirKey: rEncKey, - ourObfs: iObfs, - theirObfs: rObfs, - ourNonce: make([]byte, chacha20.NonceSize), - theirNonce: make([]byte, chacha20.NonceSize), - } - } - newState.ourSeq = newState.ourNonce[4:] - newState.theirSeq = newState.theirNonce[4:] - state = &newState - if first { - close(stateReady) - first = false - } - } - if s.Err() != nil { - log.Fatal(s.Err()) - } - }() - <-stateReady - - addr, err := net.ResolveUDPAddr("udp", *bind) - if err != nil { - log.Fatal(err) - } - connBind, err := net.ListenUDP("udp", addr) - if err != nil { - log.Fatal(err) - } - - var connLocal *net.UDPConn - var connRemote *net.UDPConn - var addrLocal *net.UDPAddr - var addrRemote *net.UDPAddr - addr, err = net.ResolveUDPAddr("udp", *dst) - if err != nil { - log.Fatal(err) - } - if *responder { - connLocal, err = net.DialUDP("udp", nil, addr) - } else { - connRemote, err = net.DialUDP("udp", nil, addr) - } - if err != nil { - log.Fatal(err) - } - log.Println(*bind, "->", *dst) - - go func() { - rx := make([]byte, 1<<14) - tx := make([]byte, 1<<14) - var n int - var polyKey [32]byte - var s *chacha20.Cipher - var p *poly1305.MAC - tag := make([]byte, poly1305.TagSize) - var from *net.UDPAddr - for { - if *responder { - n, err = connLocal.Read(rx) - } else { - n, from, err = connBind.ReadFromUDP(rx) - } - if err != nil { - log.Fatal(err) - } - if *responder && addrRemote == nil { - continue - } - if !*responder && (addrLocal == nil || - from.Port != addrLocal.Port || !from.IP.Equal(addrLocal.IP)) { - addrLocal = from - } - if incr(state.ourSeq[5:]) { - incr(state.ourSeq[:5]) - } - copy(tx, state.ourSeq[5:]) - s, err = chacha20.NewUnauthenticatedCipher(state.ourKey, state.ourNonce) - if err != nil { - log.Fatal(err) - } - clear(polyKey[:]) - s.XORKeyStream(polyKey[:], polyKey[:]) - s.SetCounter(1) - s.XORKeyStream(tx[8:], rx[:n]) - p = poly1305.New(&polyKey) - mustWrite(p, state.ourSeq) - mustWrite(p, tx[8:8+n]) - p.Sum(tag[:0]) - copy(tx[3:8], tag) - state.ourObfs.Encrypt(tx[:8], tx[:8]) - if *responder { - connBind.WriteTo(tx[:8+n], addrRemote) - } else { - connRemote.Write(tx[:8+n]) - } - } - }() - go func(state **State) { - rx := make([]byte, 1<<14) - tx := make([]byte, 1<<14) - var n int - var polyKey [32]byte - var s *chacha20.Cipher - var p *poly1305.MAC - var from *net.UDPAddr - tag := make([]byte, poly1305.TagSize) - nonce := make([]byte, chacha20.NonceSize) - seq := nonce[4:] - var seqOur, seqTheir uint32 - for { - if *responder { - n, from, err = connBind.ReadFromUDP(rx) - } else { - n, err = connRemote.Read(rx) - } - if err != nil { - log.Fatal(err) - } - if n < 8 { - log.Println("too short") - continue - } - if *responder && (addrRemote == nil || - from.Port != addrRemote.Port || !from.IP.Equal(addrRemote.IP)) { - addrRemote = from - } - (*state).theirObfs.Decrypt(rx[:8], rx[:8]) - seqOur = uint32((*state).theirSeq[0])<<16 | - uint32((*state).theirSeq[1])<<8 | - uint32((*state).theirSeq[2]) - seqTheir = uint32(rx[0])<<16 | uint32(rx[1])<<8 | uint32(rx[2]) - if seqOur == seqTheir { - log.Println("replay") - continue - } - copy(seq, (*state).theirNonce[:5]) - copy(seq[5:], rx[:3]) - if seqTheir < seqOur && incr(seq[:5]) { - log.Fatal("seq is overflowed") - } - s, err = chacha20.NewUnauthenticatedCipher((*state).theirKey, nonce) - if err != nil { - log.Fatal(err) - } - clear(polyKey[:]) - s.XORKeyStream(polyKey[:], polyKey[:]) - s.SetCounter(1) - p = poly1305.New(&polyKey) - mustWrite(p, seq) - mustWrite(p, rx[8:n]) - p.Sum(tag[:0]) - if subtle.ConstantTimeCompare(tag[:5], rx[3:8]) != 1 { - log.Print("bad MAC") - continue - } - copy((*state).theirSeq, seq) - s.XORKeyStream(tx, rx[8:n]) - if *responder { - connLocal.Write(tx[:n-8]) - } else { - connBind.WriteTo(tx[:n-8], addrLocal) - } - } - }(&state) - exit := make(chan os.Signal, 1) - signal.Notify(exit, syscall.SIGTERM, syscall.SIGINT) - <-exit -} diff --git a/utils.go b/utils.go new file mode 100644 index 0000000..83e27ac --- /dev/null +++ b/utils.go @@ -0,0 +1,53 @@ +package udpobfs + +import ( + "io" + "log" + "net" + "time" +) + +const BufLen = 1 << 14 + +var ( + PingDuration = 10 * time.Second + LifetimeDuration = time.Minute +) + +func MustWrite(w io.Writer, data []byte) { + if n, err := w.Write(data); err != nil || n != len(data) { + log.Fatal("non full write") + } +} + +func Incr(buf []byte) (overflow bool) { + for i := len(buf) - 1; i >= 0; i-- { + buf[i]++ + if buf[i] != 0 { + return + } + } + overflow = true + return +} + +func MustResolveUDPAddr(addr string) *net.UDPAddr { + a, err := net.ResolveUDPAddr("udp", addr) + if err != nil { + log.Fatal(err) + } + return a +} + +func MustResolveTCPAddr(addr string) *net.TCPAddr { + a, err := net.ResolveTCPAddr("tcp", addr) + if err != nil { + log.Fatal(err) + } + return a +} + +type Buf struct { + Buf *[BufLen]byte + N int +} diff --git a/x509.go b/x509.go new file mode 100644 index 0000000..c79db00 --- /dev/null +++ b/x509.go @@ -0,0 +1,103 @@ +/* +udpobfs -- simple point-to-point UDP obfuscation proxy +Copyright (C) 2023 Sergey Matveev + +This program is free software: you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation, version 3 of the License. + +This program is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with this program. If not, see . +*/ + +package udpobfs + +import ( + "crypto/x509" + "encoding/pem" + "errors" + "os" +) + +func CertificateFromFile(p string) (b []byte, c *x509.Certificate, err error) { + var data []byte + data, err = os.ReadFile(p) + if err != nil { + return + } + var block *pem.Block + for len(data) > 0 { + block, data = pem.Decode(data) + if block == nil { + continue + } + if block.Type == "CERTIFICATE" { + b = block.Bytes + c, err = x509.ParseCertificate(b) + return + } + } + err = errors.New("no CERTIFICATE found in PEM") + return +} + +func PrivateKeyFromFile(p string) (prv interface{}, err error) { + var data []byte + data, err = os.ReadFile(p) + if err != nil { + return + } + var block *pem.Block + for len(data) > 0 { + block, data = pem.Decode(data) + if block == nil { + continue + } + switch block.Type { + case "PRIVATE KEY": + prv, err = x509.ParsePKCS8PrivateKey(block.Bytes) + return + case "EC PRIVATE KEY": + prv, err = x509.ParseECPrivateKey(block.Bytes) + return + } + } + err = errors.New("no PRIVATE KEY found in PEM") + return +} + +func CertPoolFromFile(p string) ( + certs []*x509.Certificate, pool *x509.CertPool, err error, +) { + var data []byte + data, err = os.ReadFile(p) + if err != nil { + return + } + pool = x509.NewCertPool() + var block *pem.Block + for len(data) > 0 { + block, data = pem.Decode(data) + if block == nil { + err = errors.New("can not decode PEM") + return + } + if block.Type != "CERTIFICATE" { + err = errors.New("non CERTIFICATE found in PEM") + return + } + var ca *x509.Certificate + ca, err = x509.ParseCertificate(block.Bytes) + if err != nil { + return + } + certs = append(certs, ca) + pool.AddCert(ca) + } + return +} -- 2.44.0