| 1 | package sdk |
| 2 | |
| 3 | import ( |
| 4 | "bufio" |
| 5 | "bytes" |
| 6 | "context" |
| 7 | "crypto/rand" |
| 8 | "crypto/tls" |
| 9 | "encoding/hex" |
| 10 | "errors" |
| 11 | "fmt" |
| 12 | "io" |
| 13 | "net" |
| 14 | "net/url" |
| 15 | "sync" |
| 16 | "time" |
| 17 | |
| 18 | "github.com/rs/zerolog/log" |
| 19 | |
| 20 | "github.com/gosuda/portal-tunnel/v2/portal/keyless" |
| 21 | "github.com/gosuda/portal-tunnel/v2/types" |
| 22 | "github.com/gosuda/portal-tunnel/v2/utils" |
| 23 | ) |
| 24 | |
| 25 | const ( |
| 26 | mitmProbeExporterLabel = "Portal-MITM-Probe-v1" |
| 27 | mitmProbePeekTimeout = 100 * time.Millisecond |
| 28 | mitmProbePaddingMin = 96 |
| 29 | mitmProbePaddingMax = 320 |
| 30 | |
| 31 | defaultMITMProbeCooldown = 30 * time.Second |
| 32 | defaultMITMProbeTimeout = 5 * time.Second |
| 33 | ) |
| 34 | |
| 35 | type MITMProbeReport struct { |
| 36 | RelayURL string |
| 37 | PublicURL string |
| 38 | Address string |
| 39 | ECHAccepted bool |
| 40 | Detected bool |
| 41 | Reason string |
| 42 | } |
| 43 | |
| 44 | type mitmProbePending struct { |
| 45 | expected []byte |
| 46 | resultCh chan string |
| 47 | } |
| 48 | |
| 49 | type mitmManager struct { |
| 50 | ctx context.Context |
| 51 | listener *listener |
| 52 | ban bool |
| 53 | |
| 54 | mu sync.Mutex |
| 55 | pending map[string]*mitmProbePending |
| 56 | inFlight bool |
| 57 | lastAt time.Time |
| 58 | } |
| 59 | |
| 60 | func newMITMManager(ctx context.Context, listener *listener, ban bool) *mitmManager { |
| 61 | return &mitmManager{ |
| 62 | ctx: ctx, |
| 63 | ban: ban, |
| 64 | listener: listener, |
| 65 | pending: make(map[string]*mitmProbePending), |
| 66 | } |
| 67 | } |
| 68 | |
| 69 | func (m *mitmManager) reset() { |
| 70 | m.mu.Lock() |
| 71 | clear(m.pending) |
| 72 | m.inFlight = false |
| 73 | m.lastAt = time.Time{} |
| 74 | m.mu.Unlock() |
| 75 | } |
| 76 | |
| 77 | func (m *mitmManager) probeTLSPassthrough(ctx context.Context) (MITMProbeReport, error) { |
| 78 | l := m.listener |
| 79 | if l == nil || l.relayURL == nil { |
| 80 | return MITMProbeReport{}, errors.New("listener is not ready") |
| 81 | } |
| 82 | |
| 83 | lease, ok := l.leaseSnapshot() |
| 84 | if !ok { |
| 85 | return MITMProbeReport{}, errors.New("listener is not registered") |
| 86 | } |
| 87 | if lease.hostname == "" { |
| 88 | return MITMProbeReport{}, errors.New("listener hostname is unavailable") |
| 89 | } |
| 90 | |
| 91 | publicURL := l.publicURLForLease(lease) |
| 92 | if publicURL == "" { |
| 93 | return MITMProbeReport{}, errors.New("listener is not registered") |
| 94 | } |
| 95 | |
| 96 | report := MITMProbeReport{ |
| 97 | RelayURL: l.relayURL.String(), |
| 98 | PublicURL: publicURL, |
| 99 | Address: l.identity.Address, |
| 100 | } |
| 101 | |
| 102 | probeCtx, cancel := context.WithTimeout(ctx, defaultMITMProbeTimeout) |
| 103 | defer cancel() |
| 104 | |
| 105 | nonceRaw := make([]byte, 16) |
| 106 | if _, err := io.ReadFull(rand.Reader, nonceRaw); err != nil { |
| 107 | return report, fmt.Errorf("generate probe nonce: %w", err) |
| 108 | } |
| 109 | nonceHex := hex.EncodeToString(nonceRaw) |
| 110 | |
| 111 | dialAddr, err := m.probeDialAddress(publicURL) |
| 112 | if err != nil { |
| 113 | return report, err |
| 114 | } |
| 115 | |
| 116 | probeTLSConf := &tls.Config{ |
| 117 | ServerName: lease.hostname, |
| 118 | InsecureSkipVerify: true, |
| 119 | MinVersion: keyless.MinTLSVersion(len(lease.echConfigList) > 0), |
| 120 | EncryptedClientHelloConfigList: bytes.Clone(lease.echConfigList), |
| 121 | } |
| 122 | |
| 123 | dialer := &tls.Dialer{ |
| 124 | NetDialer: &net.Dialer{Timeout: l.dialTimeout}, |
| 125 | Config: probeTLSConf, |
| 126 | } |
| 127 | conn, err := dialer.DialContext(probeCtx, "tcp", dialAddr) |
| 128 | if err != nil { |
| 129 | return report, fmt.Errorf("dial mitm probe: %w", err) |
| 130 | } |
| 131 | defer conn.Close() |
| 132 | |
| 133 | tlsConn, ok := conn.(*tls.Conn) |
| 134 | if !ok { |
| 135 | return report, errors.New("mitm probe connection is not tls") |
| 136 | } |
| 137 | |
| 138 | clientState := tlsConn.ConnectionState() |
| 139 | report.ECHAccepted = clientState.ECHAccepted |
| 140 | expected, err := (&clientState).ExportKeyingMaterial(mitmProbeExporterLabel, nil, 32) |
| 141 | if err != nil { |
| 142 | return report, fmt.Errorf("export client probe keying material: %w", err) |
| 143 | } |
| 144 | resultCh, cleanupProbe := m.startProbe(nonceHex, expected) |
| 145 | defer cleanupProbe() |
| 146 | |
| 147 | paddingLen := mitmProbePaddingMin |
| 148 | if paddingRange := mitmProbePaddingMax - mitmProbePaddingMin; paddingRange > 0 { |
| 149 | var paddingSeed [1]byte |
| 150 | if _, err := io.ReadFull(rand.Reader, paddingSeed[:]); err != nil { |
| 151 | return report, fmt.Errorf("generate probe padding length: %w", err) |
| 152 | } |
| 153 | paddingLen += int(paddingSeed[0]) % (paddingRange + 1) |
| 154 | } |
| 155 | |
| 156 | frame := make([]byte, len(nonceRaw)+paddingLen) |
| 157 | if _, err := io.ReadFull(rand.Reader, frame); err != nil { |
| 158 | return report, fmt.Errorf("generate probe frame: %w", err) |
| 159 | } |
| 160 | copy(frame, nonceRaw) |
| 161 | if _, err := conn.Write(frame); err != nil { |
| 162 | return report, fmt.Errorf("write mitm probe: %w", err) |
| 163 | } |
| 164 | |
| 165 | select { |
| 166 | case reason := <-resultCh: |
| 167 | report.Detected = reason != "" |
| 168 | report.Reason = reason |
| 169 | case <-probeCtx.Done(): |
| 170 | report.Reason = types.MITMProbeReasonProbeTimeout |
| 171 | if !errors.Is(probeCtx.Err(), context.DeadlineExceeded) { |
| 172 | return report, probeCtx.Err() |
| 173 | } |
| 174 | } |
| 175 | return report, nil |
| 176 | } |
| 177 | |
| 178 | func (m *mitmManager) probeDialAddress(publicURL string) (string, error) { |
| 179 | l := m.listener |
| 180 | if l == nil || l.relayURL == nil { |
| 181 | return "", errors.New("listener is not ready") |
| 182 | } |
| 183 | parsedURL, err := url.Parse(publicURL) |
| 184 | if err != nil { |
| 185 | return "", fmt.Errorf("parse public url: %w", err) |
| 186 | } |
| 187 | |
| 188 | dialHost := parsedURL.Host |
| 189 | if utils.IsLocalRelayHost(l.relayURL.Hostname()) { |
| 190 | dialHost = l.relayURL.Host |
| 191 | } |
| 192 | return utils.EnsurePort(dialHost), nil |
| 193 | } |
| 194 | |
| 195 | func (m *mitmManager) maybeStart() { |
| 196 | l := m.listener |
| 197 | select { |
| 198 | case <-l.doneCh: |
| 199 | return |
| 200 | default: |
| 201 | } |
| 202 | |
| 203 | m.mu.Lock() |
| 204 | if m.inFlight || !m.lastAt.IsZero() && time.Since(m.lastAt) < defaultMITMProbeCooldown { |
| 205 | m.mu.Unlock() |
| 206 | return |
| 207 | } |
| 208 | m.inFlight = true |
| 209 | m.mu.Unlock() |
| 210 | |
| 211 | go func() { |
| 212 | report, err := m.probeTLSPassthrough(m.ctx) |
| 213 | success := err == nil && report.Reason != types.MITMProbeReasonProbeTimeout |
| 214 | m.mu.Lock() |
| 215 | m.inFlight = false |
| 216 | if success { |
| 217 | m.lastAt = time.Now() |
| 218 | } |
| 219 | m.mu.Unlock() |
| 220 | m.logResult(report, err) |
| 221 | }() |
| 222 | } |
| 223 | |
| 224 | func (m *mitmManager) logResult(report MITMProbeReport, err error) { |
| 225 | l := m.listener |
| 226 | if l == nil { |
| 227 | return |
| 228 | } |
| 229 | closed := false |
| 230 | select { |
| 231 | case <-l.doneCh: |
| 232 | closed = true |
| 233 | default: |
| 234 | } |
| 235 | relayURL := "" |
| 236 | if l.relayURL != nil { |
| 237 | relayURL = l.relayURL.String() |
| 238 | } |
| 239 | switch { |
| 240 | case closed: |
| 241 | return |
| 242 | case err != nil: |
| 243 | if errors.Is(err, context.Canceled) || errors.Is(err, net.ErrClosed) { |
| 244 | return |
| 245 | } |
| 246 | log.Warn(). |
| 247 | Err(err). |
| 248 | Bool("ech_accepted", report.ECHAccepted). |
| 249 | Str("relay_url", relayURL). |
| 250 | Str("address", l.identity.Address). |
| 251 | Msg("tls passthrough self-probe failed") |
| 252 | case report.Reason == types.MITMProbeReasonProbeTimeout: |
| 253 | log.Warn(). |
| 254 | Bool("ech_accepted", report.ECHAccepted). |
| 255 | Str("relay_url", report.RelayURL). |
| 256 | Str("public_url", report.PublicURL). |
| 257 | Str("address", report.Address). |
| 258 | Msg("tls self-probe timed out before passthrough could be verified") |
| 259 | case report.Detected: |
| 260 | event := log.Warn(). |
| 261 | Bool("ban_mitm", m.ban). |
| 262 | Bool("ech_accepted", report.ECHAccepted). |
| 263 | Str("reason", report.Reason). |
| 264 | Str("relay_url", report.RelayURL). |
| 265 | Str("public_url", report.PublicURL). |
| 266 | Str("address", report.Address) |
| 267 | if m.ban { |
| 268 | event.Msg("tls termination suspected by self-probe; banning relay") |
| 269 | if l.relaySet != nil && report.RelayURL != "" { |
| 270 | l.relaySet.UnconfirmRelayURL(report.RelayURL) |
| 271 | l.relaySet.BanRelayURL(report.RelayURL) |
| 272 | } |
| 273 | _ = l.Close() |
| 274 | return |
| 275 | } |
| 276 | event.Msg("tls termination suspected by self-probe") |
| 277 | default: |
| 278 | log.Debug(). |
| 279 | Bool("ech_accepted", report.ECHAccepted). |
| 280 | Str("relay_url", report.RelayURL). |
| 281 | Str("public_url", report.PublicURL). |
| 282 | Str("address", report.Address). |
| 283 | Msg("tls passthrough self-probe passed") |
| 284 | } |
| 285 | } |
| 286 | |
| 287 | func (m *mitmManager) maybeHandleConn(conn net.Conn) (net.Conn, bool, error) { |
| 288 | if conn == nil { |
| 289 | return conn, false, nil |
| 290 | } |
| 291 | |
| 292 | m.mu.Lock() |
| 293 | hasPending := len(m.pending) > 0 |
| 294 | m.mu.Unlock() |
| 295 | if !hasPending { |
| 296 | return conn, false, nil |
| 297 | } |
| 298 | |
| 299 | tlsConn, ok := conn.(*tls.Conn) |
| 300 | if !ok { |
| 301 | return conn, false, nil |
| 302 | } |
| 303 | |
| 304 | frameSize := 16 |
| 305 | reader := bufio.NewReaderSize(conn, frameSize) |
| 306 | _ = conn.SetReadDeadline(time.Now().Add(mitmProbePeekTimeout)) |
| 307 | peeked, err := reader.Peek(frameSize) |
| 308 | defer conn.SetReadDeadline(time.Time{}) |
| 309 | if err != nil { |
| 310 | return wrapBufferedConn(conn, reader), false, nil |
| 311 | } |
| 312 | |
| 313 | nonceHex := hex.EncodeToString(peeked[:frameSize]) |
| 314 | m.mu.Lock() |
| 315 | _, ok = m.pending[nonceHex] |
| 316 | m.mu.Unlock() |
| 317 | if !ok { |
| 318 | return wrapBufferedConn(conn, reader), false, nil |
| 319 | } |
| 320 | |
| 321 | defer conn.Close() |
| 322 | |
| 323 | frame := make([]byte, frameSize) |
| 324 | if _, err := io.ReadFull(reader, frame); err != nil { |
| 325 | return nil, true, fmt.Errorf("read mitm probe frame: %w", err) |
| 326 | } |
| 327 | |
| 328 | serverState := tlsConn.ConnectionState() |
| 329 | actual, err := (&serverState).ExportKeyingMaterial(mitmProbeExporterLabel, nil, 32) |
| 330 | if err != nil { |
| 331 | return nil, true, fmt.Errorf("export server probe keying material: %w", err) |
| 332 | } |
| 333 | |
| 334 | m.completeProbe(nonceHex, actual) |
| 335 | return nil, true, nil |
| 336 | } |
| 337 | |
| 338 | func (m *mitmManager) startProbe(nonce string, expected []byte) (<-chan string, func()) { |
| 339 | m.mu.Lock() |
| 340 | state := &mitmProbePending{ |
| 341 | expected: bytes.Clone(expected), |
| 342 | resultCh: make(chan string, 1), |
| 343 | } |
| 344 | m.pending[nonce] = state |
| 345 | m.mu.Unlock() |
| 346 | |
| 347 | return state.resultCh, func() { |
| 348 | m.mu.Lock() |
| 349 | delete(m.pending, nonce) |
| 350 | m.mu.Unlock() |
| 351 | } |
| 352 | } |
| 353 | |
| 354 | func (m *mitmManager) completeProbe(nonce string, actual []byte) { |
| 355 | m.mu.Lock() |
| 356 | state := m.pending[nonce] |
| 357 | m.mu.Unlock() |
| 358 | if state == nil { |
| 359 | return |
| 360 | } |
| 361 | |
| 362 | reason := "" |
| 363 | if !bytes.Equal(state.expected, actual) { |
| 364 | reason = types.MITMProbeReasonExporterMismatch |
| 365 | } |
| 366 | |
| 367 | select { |
| 368 | case state.resultCh <- reason: |
| 369 | default: |
| 370 | } |
| 371 | } |
| 372 | |
| 373 | type mitmProbeConn struct { |
| 374 | net.Conn |
| 375 | manager *mitmManager |
| 376 | startOnce sync.Once |
| 377 | } |
| 378 | |
| 379 | func (c *mitmProbeConn) Read(p []byte) (int, error) { |
| 380 | n, err := c.Conn.Read(p) |
| 381 | if n > 0 { |
| 382 | c.startOnce.Do(func() { |
| 383 | c.manager.maybeStart() |
| 384 | }) |
| 385 | } |
| 386 | return n, err |
| 387 | } |
| 388 | |
| 389 | func (c *mitmProbeConn) Write(p []byte) (int, error) { |
| 390 | n, err := c.Conn.Write(p) |
| 391 | if n > 0 { |
| 392 | c.startOnce.Do(func() { |
| 393 | c.manager.maybeStart() |
| 394 | }) |
| 395 | } |
| 396 | return n, err |
| 397 | } |