-
-
Notifications
You must be signed in to change notification settings - Fork 692
/
server.go
440 lines (407 loc) · 16.3 KB
/
server.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
// Copyright (C) 2019 Nicola Murino
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, version 3.
//
// 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
package ftpd
import (
"crypto/tls"
"crypto/x509"
"errors"
"fmt"
"net"
"os"
"path/filepath"
ftpserver "github.com/fclairamb/ftpserverlib"
"github.com/sftpgo/sdk/plugin/notifier"
"github.com/drakkan/sftpgo/v2/internal/common"
"github.com/drakkan/sftpgo/v2/internal/dataprovider"
"github.com/drakkan/sftpgo/v2/internal/logger"
"github.com/drakkan/sftpgo/v2/internal/metric"
"github.com/drakkan/sftpgo/v2/internal/plugin"
"github.com/drakkan/sftpgo/v2/internal/util"
"github.com/drakkan/sftpgo/v2/internal/version"
)
// Server implements the ftpserverlib MainDriver interface
type Server struct {
ID int
config *Configuration
initialMsg string
statusBanner string
binding Binding
tlsConfig *tls.Config
}
// NewServer returns a new FTP server driver
func NewServer(config *Configuration, configDir string, binding Binding, id int) *Server {
binding.setCiphers()
vers := version.GetServerVersion("_", false)
server := &Server{
config: config,
initialMsg: vers,
statusBanner: fmt.Sprintf("%s FTP Server", vers),
binding: binding,
ID: id,
}
if config.BannerFile != "" {
bannerFilePath := config.BannerFile
if !filepath.IsAbs(bannerFilePath) {
bannerFilePath = filepath.Join(configDir, bannerFilePath)
}
bannerContent, err := os.ReadFile(bannerFilePath)
if err == nil {
server.initialMsg = util.BytesToString(bannerContent)
} else {
logger.WarnToConsole("unable to read FTPD banner file: %v", err)
logger.Warn(logSender, "", "unable to read banner file: %v", err)
}
}
server.buildTLSConfig()
return server
}
// GetSettings returns FTP server settings
func (s *Server) GetSettings() (*ftpserver.Settings, error) {
if err := s.binding.checkPassiveIP(); err != nil {
return nil, err
}
if err := s.binding.checkSecuritySettings(); err != nil {
return nil, err
}
var portRange *ftpserver.PortRange
if s.config.PassivePortRange.Start > 0 && s.config.PassivePortRange.End > s.config.PassivePortRange.Start {
portRange = &ftpserver.PortRange{
Start: s.config.PassivePortRange.Start,
End: s.config.PassivePortRange.End,
}
}
var ftpListener net.Listener
if s.binding.HasProxy() {
listener, err := net.Listen("tcp", s.binding.GetAddress())
if err != nil {
logger.Warn(logSender, "", "error starting listener on address %v: %v", s.binding.GetAddress(), err)
return nil, err
}
ftpListener, err = common.Config.GetProxyListener(listener)
if err != nil {
logger.Warn(logSender, "", "error enabling proxy listener: %v", err)
return nil, err
}
if s.binding.TLSMode == 2 && s.tlsConfig != nil {
ftpListener = tls.NewListener(ftpListener, s.tlsConfig)
}
}
if !s.binding.isTLSModeValid() {
return nil, fmt.Errorf("unsupported TLS mode: %d", s.binding.TLSMode)
}
if !s.binding.isTLSSessionReuseValid() {
return nil, fmt.Errorf("unsupported TLS reuse mode %d", s.binding.TLSSessionReuse)
}
if (s.binding.TLSMode > 0 || s.binding.TLSSessionReuse > 0) && certMgr == nil {
return nil, errors.New("to enable TLS you need to provide a certificate")
}
return &ftpserver.Settings{
Listener: ftpListener,
ListenAddr: s.binding.GetAddress(),
PublicIPResolver: s.binding.passiveIPResolver,
PassiveTransferPortRange: portRange,
ActiveTransferPortNon20: s.config.ActiveTransfersPortNon20,
IdleTimeout: -1,
ConnectionTimeout: 20,
Banner: s.statusBanner,
TLSRequired: ftpserver.TLSRequirement(s.binding.TLSMode),
TLSSessionReuse: ftpserver.TLSSessionReuse(s.binding.TLSSessionReuse),
DisableSite: !s.config.EnableSite,
DisableActiveMode: s.config.DisableActiveMode,
EnableHASH: s.config.HASHSupport > 0,
EnableCOMB: s.config.CombineSupport > 0,
DefaultTransferType: ftpserver.TransferTypeBinary,
IgnoreASCIITranferType: s.binding.IgnoreASCIITransferType == 1,
ActiveConnectionsCheck: ftpserver.DataConnectionRequirement(s.binding.ActiveConnectionsSecurity),
PasvConnectionsCheck: ftpserver.DataConnectionRequirement(s.binding.PassiveConnectionsSecurity),
}, nil
}
// ClientConnected is called to send the very first welcome message
func (s *Server) ClientConnected(cc ftpserver.ClientContext) (string, error) {
cc.SetDebug(s.binding.Debug)
ipAddr := util.GetIPFromRemoteAddress(cc.RemoteAddr().String())
common.Connections.AddClientConnection(ipAddr)
if common.IsBanned(ipAddr, common.ProtocolFTP) {
logger.Log(logger.LevelDebug, common.ProtocolFTP, "", "connection refused, ip %q is banned", ipAddr)
return "Access denied: banned client IP", common.ErrConnectionDenied
}
if err := common.Connections.IsNewConnectionAllowed(ipAddr, common.ProtocolFTP); err != nil {
logger.Log(logger.LevelDebug, common.ProtocolFTP, "", "connection not allowed from ip %q: %v", ipAddr, err)
return "Access denied", err
}
_, err := common.LimitRate(common.ProtocolFTP, ipAddr)
if err != nil {
return fmt.Sprintf("Access denied: %v", err.Error()), err
}
if err := common.Config.ExecutePostConnectHook(ipAddr, common.ProtocolFTP); err != nil {
return "Access denied", err
}
connID := fmt.Sprintf("%v_%v", s.ID, cc.ID())
user := dataprovider.User{}
connection := &Connection{
BaseConnection: common.NewBaseConnection(connID, common.ProtocolFTP, cc.LocalAddr().String(),
cc.RemoteAddr().String(), user),
clientContext: cc,
}
err = common.Connections.Add(connection)
return s.initialMsg, err
}
// ClientDisconnected is called when the user disconnects, even if he never authenticated
func (s *Server) ClientDisconnected(cc ftpserver.ClientContext) {
connID := fmt.Sprintf("%v_%v_%v", common.ProtocolFTP, s.ID, cc.ID())
common.Connections.Remove(connID)
common.Connections.RemoveClientConnection(util.GetIPFromRemoteAddress(cc.RemoteAddr().String()))
}
// AuthUser authenticates the user and selects an handling driver
func (s *Server) AuthUser(cc ftpserver.ClientContext, username, password string) (ftpserver.ClientDriver, error) {
loginMethod := dataprovider.LoginMethodPassword
if verified, ok := cc.Extra().(bool); ok && verified {
loginMethod = dataprovider.LoginMethodTLSCertificateAndPwd
}
ipAddr := util.GetIPFromRemoteAddress(cc.RemoteAddr().String())
user, err := dataprovider.CheckUserAndPass(username, password, ipAddr, common.ProtocolFTP)
if err != nil {
user.Username = username
updateLoginMetrics(&user, ipAddr, loginMethod, err)
return nil, dataprovider.ErrInvalidCredentials
}
connection, err := s.validateUser(user, cc, loginMethod)
defer updateLoginMetrics(&user, ipAddr, loginMethod, err)
if err != nil {
return nil, err
}
setStartDirectory(user.Filters.StartDirectory, cc)
connection.Log(logger.LevelInfo, "User %q logged in with %q from ip %q, TLS enabled? %t",
user.Username, loginMethod, ipAddr, cc.HasTLSForControl())
dataprovider.UpdateLastLogin(&user)
return connection, nil
}
// PreAuthUser implements the MainDriverExtensionUserVerifier interface
func (s *Server) PreAuthUser(cc ftpserver.ClientContext, username string) error {
if s.binding.TLSMode == 0 && s.tlsConfig != nil {
user, err := dataprovider.GetFTPPreAuthUser(username, util.GetIPFromRemoteAddress(cc.RemoteAddr().String()))
if err == nil {
if user.Filters.FTPSecurity == 1 {
return cc.SetTLSRequirement(ftpserver.MandatoryEncryption)
}
return nil
}
if !errors.Is(err, util.ErrNotFound) {
logger.Error(logSender, fmt.Sprintf("%v_%v_%v", common.ProtocolFTP, s.ID, cc.ID()),
"unable to get user on pre auth: %v", err)
return common.ErrInternalFailure
}
}
return nil
}
// WrapPassiveListener implements the MainDriverExtensionPassiveWrapper interface
func (s *Server) WrapPassiveListener(listener net.Listener) (net.Listener, error) {
if s.binding.HasProxy() {
return common.Config.GetProxyListener(listener)
}
return listener, nil
}
// VerifyConnection checks whether a user should be authenticated using a client certificate without prompting for a password
func (s *Server) VerifyConnection(cc ftpserver.ClientContext, user string, tlsConn *tls.Conn) (ftpserver.ClientDriver, error) {
if !s.binding.isMutualTLSEnabled() {
return nil, nil
}
cc.SetExtra(false)
if tlsConn != nil {
state := tlsConn.ConnectionState()
if len(state.PeerCertificates) > 0 {
ipAddr := util.GetIPFromRemoteAddress(cc.RemoteAddr().String())
dbUser, err := dataprovider.CheckUserBeforeTLSAuth(user, ipAddr, common.ProtocolFTP, state.PeerCertificates[0])
if err != nil {
dbUser.Username = user
updateLoginMetrics(&dbUser, ipAddr, dataprovider.LoginMethodTLSCertificate, err)
return nil, dataprovider.ErrInvalidCredentials
}
if dbUser.IsTLSVerificationEnabled() {
dbUser, err = dataprovider.CheckUserAndTLSCert(user, ipAddr, common.ProtocolFTP, state.PeerCertificates[0])
if err != nil {
return nil, err
}
cc.SetExtra(true)
if dbUser.IsLoginMethodAllowed(dataprovider.LoginMethodTLSCertificate, common.ProtocolFTP) {
connection, err := s.validateUser(dbUser, cc, dataprovider.LoginMethodTLSCertificate)
defer updateLoginMetrics(&dbUser, ipAddr, dataprovider.LoginMethodTLSCertificate, err)
if err != nil {
return nil, err
}
setStartDirectory(dbUser.Filters.StartDirectory, cc)
connection.Log(logger.LevelInfo, "User id: %d, logged in with FTP using a TLS certificate, username: %q, home_dir: %q remote addr: %q",
dbUser.ID, dbUser.Username, dbUser.HomeDir, ipAddr)
dataprovider.UpdateLastLogin(&dbUser)
return connection, nil
}
}
}
}
return nil, nil
}
func (s *Server) buildTLSConfig() {
if certMgr != nil {
certID := common.DefaultTLSKeyPaidID
if getConfigPath(s.binding.CertificateFile, "") != "" && getConfigPath(s.binding.CertificateKeyFile, "") != "" {
certID = s.binding.GetAddress()
}
if !certMgr.HasCertificate(certID) {
return
}
s.tlsConfig = &tls.Config{
GetCertificate: certMgr.GetCertificateFunc(certID),
MinVersion: util.GetTLSVersion(s.binding.MinTLSVersion),
CipherSuites: s.binding.ciphers,
}
logger.Debug(logSender, "", "configured TLS cipher suites for binding %q: %v, certID: %v",
s.binding.GetAddress(), s.binding.ciphers, certID)
if s.binding.isMutualTLSEnabled() {
s.tlsConfig.ClientCAs = certMgr.GetRootCAs()
if s.binding.TLSSessionReuse != int(ftpserver.TLSSessionReuseRequired) {
s.tlsConfig.VerifyConnection = s.verifyTLSConnection
}
switch s.binding.ClientAuthType {
case 1:
s.tlsConfig.ClientAuth = tls.RequireAndVerifyClientCert
case 2:
s.tlsConfig.ClientAuth = tls.VerifyClientCertIfGiven
}
}
}
}
// GetTLSConfig returns the TLS configuration for this server
func (s *Server) GetTLSConfig() (*tls.Config, error) {
if s.tlsConfig != nil {
return s.tlsConfig, nil
}
return nil, errors.New("no TLS certificate configured")
}
// VerifyTLSConnectionState implements the MainDriverExtensionTLSConnectionStateVerifier extension
func (s *Server) VerifyTLSConnectionState(_ ftpserver.ClientContext, cs tls.ConnectionState) error {
if !s.binding.isMutualTLSEnabled() {
return nil
}
return s.verifyTLSConnection(cs)
}
func (s *Server) verifyTLSConnection(state tls.ConnectionState) error {
if certMgr != nil {
var clientCrt *x509.Certificate
var clientCrtName string
if len(state.PeerCertificates) > 0 {
clientCrt = state.PeerCertificates[0]
clientCrtName = clientCrt.Subject.String()
}
if len(state.VerifiedChains) == 0 {
if s.binding.ClientAuthType == 2 {
return nil
}
logger.Warn(logSender, "", "TLS connection cannot be verified: unable to get verification chain")
return errors.New("TLS connection cannot be verified: unable to get verification chain")
}
for _, verifiedChain := range state.VerifiedChains {
var caCrt *x509.Certificate
if len(verifiedChain) > 0 {
caCrt = verifiedChain[len(verifiedChain)-1]
}
if certMgr.IsRevoked(clientCrt, caCrt) {
logger.Debug(logSender, "", "tls handshake error, client certificate %q has beed revoked", clientCrtName)
return common.ErrCrtRevoked
}
}
}
return nil
}
func (s *Server) validateUser(user dataprovider.User, cc ftpserver.ClientContext, loginMethod string) (*Connection, error) {
connectionID := fmt.Sprintf("%v_%v_%v", common.ProtocolFTP, s.ID, cc.ID())
if !filepath.IsAbs(user.HomeDir) {
logger.Warn(logSender, connectionID, "user %q has an invalid home dir: %q. Home dir must be an absolute path, login not allowed",
user.Username, user.HomeDir)
return nil, fmt.Errorf("cannot login user with invalid home dir: %q", user.HomeDir)
}
if util.Contains(user.Filters.DeniedProtocols, common.ProtocolFTP) {
logger.Info(logSender, connectionID, "cannot login user %q, protocol FTP is not allowed", user.Username)
return nil, fmt.Errorf("protocol FTP is not allowed for user %q", user.Username)
}
if !user.IsLoginMethodAllowed(loginMethod, common.ProtocolFTP) {
logger.Info(logSender, connectionID, "cannot login user %q, %v login method is not allowed",
user.Username, loginMethod)
return nil, fmt.Errorf("login method %v is not allowed for user %q", loginMethod, user.Username)
}
if user.MustSetSecondFactorForProtocol(common.ProtocolFTP) {
logger.Info(logSender, connectionID, "cannot login user %q, second factor authentication is not set",
user.Username)
return nil, fmt.Errorf("second factor authentication is not set for user %q", user.Username)
}
if user.MaxSessions > 0 {
activeSessions := common.Connections.GetActiveSessions(user.Username)
if activeSessions >= user.MaxSessions {
logger.Info(logSender, connectionID, "authentication refused for user: %q, too many open sessions: %v/%v",
user.Username, activeSessions, user.MaxSessions)
return nil, fmt.Errorf("too many open sessions: %v", activeSessions)
}
}
remoteAddr := cc.RemoteAddr().String()
if !user.IsLoginFromAddrAllowed(remoteAddr) {
logger.Info(logSender, connectionID, "cannot login user %q, remote address is not allowed: %v",
user.Username, remoteAddr)
return nil, fmt.Errorf("login for user %q is not allowed from this address: %v", user.Username, remoteAddr)
}
err := user.CheckFsRoot(connectionID)
if err != nil {
errClose := user.CloseFs()
logger.Warn(logSender, connectionID, "unable to check fs root: %v close fs error: %v", err, errClose)
return nil, common.ErrInternalFailure
}
connection := &Connection{
BaseConnection: common.NewBaseConnection(fmt.Sprintf("%v_%v", s.ID, cc.ID()), common.ProtocolFTP,
cc.LocalAddr().String(), remoteAddr, user),
clientContext: cc,
}
err = common.Connections.Swap(connection)
if err != nil {
errClose := user.CloseFs()
logger.Warn(logSender, connectionID, "unable to swap connection: %v, close fs error: %v", err, errClose)
return nil, err
}
return connection, nil
}
func setStartDirectory(startDirectory string, cc ftpserver.ClientContext) {
if startDirectory == "" {
return
}
cc.SetPath(startDirectory)
}
func updateLoginMetrics(user *dataprovider.User, ip, loginMethod string, err error) {
metric.AddLoginAttempt(loginMethod)
if err == nil {
plugin.Handler.NotifyLogEvent(notifier.LogEventTypeLoginOK, common.ProtocolFTP, user.Username, ip, "", nil)
common.DelayLogin(nil)
} else if err != common.ErrInternalFailure {
logger.ConnectionFailedLog(user.Username, ip, loginMethod, common.ProtocolFTP, err.Error())
event := common.HostEventLoginFailed
logEv := notifier.LogEventTypeLoginFailed
if errors.Is(err, util.ErrNotFound) {
event = common.HostEventUserNotFound
logEv = notifier.LogEventTypeLoginNoUser
}
common.AddDefenderEvent(ip, common.ProtocolFTP, event)
plugin.Handler.NotifyLogEvent(logEv, common.ProtocolFTP, user.Username, ip, "", err)
if loginMethod != dataprovider.LoginMethodTLSCertificate {
common.DelayLogin(err)
}
}
metric.AddLoginResult(loginMethod, err)
dataprovider.ExecutePostLoginHook(user, loginMethod, ip, common.ProtocolFTP, err)
}