forked from juanfont/headscale
-
Notifications
You must be signed in to change notification settings - Fork 2
/
oidc.go
772 lines (669 loc) · 19.6 KB
/
oidc.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
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
package headscale
import (
"bytes"
"context"
"crypto/rand"
"encoding/hex"
"errors"
"fmt"
"html/template"
"net/http"
"strings"
"time"
"github.com/coreos/go-oidc/v3/oidc"
"github.com/gorilla/mux"
"github.com/rs/zerolog/log"
"golang.org/x/oauth2"
"tailscale.com/types/key"
)
const (
randomByteSize = 16
errEmptyOIDCCallbackParams = Error("empty OIDC callback params")
errNoOIDCIDToken = Error("could not extract ID Token for OIDC callback")
errOIDCAllowedDomains = Error("authenticated principal does not match any allowed domain")
errOIDCAllowedGroups = Error("authenticated principal is not in any allowed group")
errOIDCAllowedUsers = Error("authenticated principal does not match any allowed user")
errOIDCInvalidMachineState = Error(
"requested machine state key expired before authorisation completed",
)
errOIDCNodeKeyMissing = Error("could not get node key from cache")
)
type IDTokenClaims struct {
Name string `json:"name,omitempty"`
Groups []string `json:"groups,omitempty"`
Email string `json:"email,omitempty"`
Phone string `json:"phone_number"`
Username string `json:"preferred_username,omitempty"`
}
func (h *Headscale) initOIDC() error {
var err error
// grab oidc config if it hasn't been already
if h.oauth2Config == nil {
h.oidcProvider, err = oidc.NewProvider(context.Background(), h.cfg.OIDC.Issuer)
if err != nil {
log.Error().
Err(err).
Caller().
Msgf("Could not retrieve OIDC Config: %s", err.Error())
return err
}
h.oauth2Config = &oauth2.Config{
ClientID: h.cfg.OIDC.ClientID,
ClientSecret: h.cfg.OIDC.ClientSecret,
Endpoint: h.oidcProvider.Endpoint(),
RedirectURL: fmt.Sprintf(
"%s/oidc/callback",
strings.TrimSuffix(h.cfg.ServerURL, "/"),
),
Scopes: h.cfg.OIDC.Scope,
}
}
return nil
}
func (h *Headscale) determineTokenExpiration(idTokenExpiration time.Time) time.Time {
if h.cfg.OIDC.UseExpiryFromToken {
return idTokenExpiration
}
return time.Now().Add(h.cfg.OIDC.Expiry)
}
// RegisterOIDC redirects to the OIDC provider for authentication
// Puts NodeKey in cache so the callback can retrieve it using the oidc state param
// Listens in /oidc/register/:nKey.
func (h *Headscale) RegisterOIDC(
writer http.ResponseWriter,
req *http.Request,
) {
vars := mux.Vars(req)
nodeKeyStr, ok := vars["nkey"]
log.Debug().
Caller().
Str("node_key", nodeKeyStr).
Bool("ok", ok).
Msg("Received oidc register call")
if !NodePublicKeyRegex.Match([]byte(nodeKeyStr)) {
log.Warn().Str("node_key", nodeKeyStr).Msg("Invalid node key passed to registration url")
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusUnauthorized)
_, err := writer.Write([]byte("Unauthorized"))
if err != nil {
log.Error().
Caller().
Err(err).
Msg("Failed to write response")
}
return
}
// We need to make sure we dont open for XSS style injections, if the parameter that
// is passed as a key is not parsable/validated as a NodePublic key, then fail to render
// the template and log an error.
var nodeKey key.NodePublic
err := nodeKey.UnmarshalText(
[]byte(NodePublicKeyEnsurePrefix(nodeKeyStr)),
)
if !ok || nodeKeyStr == "" || err != nil {
log.Warn().
Err(err).
Msg("Failed to parse incoming nodekey in OIDC registration")
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusBadRequest)
_, err := writer.Write([]byte("Wrong params"))
if err != nil {
log.Error().
Caller().
Err(err).
Msg("Failed to write response")
}
return
}
randomBlob := make([]byte, randomByteSize)
if _, err := rand.Read(randomBlob); err != nil {
log.Error().
Caller().
Msg("could not read 16 bytes from rand")
http.Error(writer, "Internal server error", http.StatusInternalServerError)
return
}
stateStr := hex.EncodeToString(randomBlob)[:32]
// place the node key into the state cache, so it can be retrieved later
h.registrationCache.Set(stateStr, NodePublicKeyStripPrefix(nodeKey), registerCacheExpiration)
// Add any extra parameter provided in the configuration to the Authorize Endpoint request
extras := make([]oauth2.AuthCodeOption, 0, len(h.cfg.OIDC.ExtraParams))
for k, v := range h.cfg.OIDC.ExtraParams {
extras = append(extras, oauth2.SetAuthURLParam(k, v))
}
authURL := h.oauth2Config.AuthCodeURL(stateStr, extras...)
log.Debug().Msgf("Redirecting to %s for authentication", authURL)
http.Redirect(writer, req, authURL, http.StatusFound)
}
type oidcCallbackTemplateConfig struct {
User string
Verb string
}
var oidcCallbackTemplate = template.Must(
template.New("oidccallback").Parse(`<html>
<body>
<h1>蜃境</h1>
<p>
{{.Verb}} 用户身份:{{.User}},你现在可关闭这个窗口了。
</p>
</body>
</html>`),
)
// OIDCCallback handles the callback from the OIDC endpoint
// Retrieves the nkey from the state cache and adds the machine to the users email user
// TODO: A confirmation page for new machines should be added to avoid phishing vulnerabilities
// TODO: Add groups information from OIDC tokens into machine HostInfo
// Listens in /oidc/callback.
func (h *Headscale) OIDCCallback(
writer http.ResponseWriter,
req *http.Request,
) {
code, state, err := validateOIDCCallbackParams(writer, req)
if err != nil {
return
}
rawIDToken, err := h.getIDTokenForOIDCCallback(req.Context(), writer, code, state)
if err != nil {
return
}
idToken, err := h.verifyIDTokenForOIDCCallback(req.Context(), writer, rawIDToken)
if err != nil {
return
}
idTokenExpiry := h.determineTokenExpiration(idToken.Expiry)
// TODO: we can use userinfo at some point to grab additional information about the user (groups membership, etc)
// userInfo, err := oidcProvider.UserInfo(context.Background(), oauth2.StaticTokenSource(oauth2Token))
// if err != nil {
// c.String(http.StatusBadRequest, fmt.Sprintf("Failed to retrieve userinfo"))
// return
// }
claims, err := extractIDTokenClaims(writer, idToken)
if err != nil {
return
}
/* cgao6: temp unused part
if err := validateOIDCAllowedDomains(writer, h.cfg.OIDC.AllowedDomains, claims); err != nil {
return
}
if err := validateOIDCAllowedGroups(writer, h.cfg.OIDC.AllowedGroups, claims); err != nil {
return
}
if err := validateOIDCAllowedUsers(writer, h.cfg.OIDC.AllowedUsers, claims); err != nil {
return
}
*/
nodeKey, machineExists, err := h.validateMachineForOIDCCallback(
writer,
state,
claims,
idTokenExpiry,
)
if err != nil || machineExists {
return
}
userName, UID, userDisName, err := getUserName(writer, claims, h.cfg.OIDC.StripEmaildomain)
if err != nil {
return
}
// register the machine if it's new
log.Debug().Msg("Registering new machine (or replace old one) after successful callback")
user, err := h.findOrCreateNewUserForOIDCCallback(writer, userName, UID, userDisName)
if err != nil {
return
}
if err := h.registerMachineForOIDCCallback(writer, user, nodeKey, idTokenExpiry); err != nil {
return
}
content, err := renderOIDCCallbackTemplate(writer, claims)
if err != nil {
return
}
writer.Header().Set("Content-Type", "text/html; charset=utf-8")
writer.WriteHeader(http.StatusOK)
if _, err := writer.Write(content.Bytes()); err != nil {
log.Error().
Caller().
Err(err).
Msg("Failed to write response")
}
}
func validateOIDCCallbackParams(
writer http.ResponseWriter,
req *http.Request,
) (string, string, error) {
code := req.URL.Query().Get("code")
state := req.URL.Query().Get("state")
if code == "" || state == "" {
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusBadRequest)
_, err := writer.Write([]byte("Wrong params"))
if err != nil {
log.Error().
Caller().
Err(err).
Msg("Failed to write response")
}
return "", "", errEmptyOIDCCallbackParams
}
return code, state, nil
}
func (h *Headscale) getIDTokenForOIDCCallback(
ctx context.Context,
writer http.ResponseWriter,
code, state string,
) (string, error) {
oauth2Token, err := h.oauth2Config.Exchange(ctx, code)
if err != nil {
log.Error().
Err(err).
Caller().
Msg("Could not exchange code for token")
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusBadRequest)
_, werr := writer.Write([]byte("Could not exchange code for token"))
if werr != nil {
log.Error().
Caller().
Err(werr).
Msg("Failed to write response")
}
return "", err
}
log.Trace().
Caller().
Str("code", code).
Str("state", state).
Msg("Got oidc callback")
rawIDToken, rawIDTokenOK := oauth2Token.Extra("id_token").(string)
if !rawIDTokenOK {
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusBadRequest)
_, err := writer.Write([]byte("Could not extract ID Token"))
if err != nil {
log.Error().
Caller().
Err(err).
Msg("Failed to write response")
}
return "", errNoOIDCIDToken
}
return rawIDToken, nil
}
func (h *Headscale) verifyIDTokenForOIDCCallback(
ctx context.Context,
writer http.ResponseWriter,
rawIDToken string,
) (*oidc.IDToken, error) {
verifier := h.oidcProvider.Verifier(&oidc.Config{ClientID: h.cfg.OIDC.ClientID})
idToken, err := verifier.Verify(ctx, rawIDToken)
if err != nil {
log.Error().
Err(err).
Caller().
Msg("failed to verify id token")
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusBadRequest)
_, werr := writer.Write([]byte("Failed to verify id token"))
if werr != nil {
log.Error().
Caller().
Err(werr).
Msg("Failed to write response")
}
return nil, err
}
return idToken, nil
}
func extractIDTokenClaims(
writer http.ResponseWriter,
idToken *oidc.IDToken,
) (*IDTokenClaims, error) {
var claims IDTokenClaims
if err := idToken.Claims(&claims); err != nil {
log.Error().
Err(err).
Caller().
Msg("Failed to decode id token claims")
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusBadRequest)
_, werr := writer.Write([]byte("Failed to decode id token claims"))
if werr != nil {
log.Error().
Caller().
Err(werr).
Msg("Failed to write response")
}
return nil, err
}
return &claims, nil
}
// validateOIDCAllowedDomains checks that if AllowedDomains is provided,
// that the authenticated principal ends with @<alloweddomain>.
func validateOIDCAllowedDomains(
writer http.ResponseWriter,
allowedDomains []string,
claims *IDTokenClaims,
) error {
if len(allowedDomains) > 0 {
if at := strings.LastIndex(claims.Email, "@"); at < 0 ||
!IsStringInSlice(allowedDomains, claims.Email[at+1:]) {
log.Error().Msg("authenticated principal does not match any allowed domain")
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusBadRequest)
_, err := writer.Write([]byte("unauthorized principal (domain mismatch)"))
if err != nil {
log.Error().
Caller().
Err(err).
Msg("Failed to write response")
}
return errOIDCAllowedDomains
}
}
return nil
}
// validateOIDCAllowedGroups checks if AllowedGroups is provided,
// and that the user has one group in the list.
// claims.Groups can be populated by adding a client scope named
// 'groups' that contains group membership.
func validateOIDCAllowedGroups(
writer http.ResponseWriter,
allowedGroups []string,
claims *IDTokenClaims,
) error {
if len(allowedGroups) > 0 {
for _, group := range allowedGroups {
if IsStringInSlice(claims.Groups, group) {
return nil
}
}
log.Error().Msg("authenticated principal not in any allowed groups")
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusBadRequest)
_, err := writer.Write([]byte("unauthorized principal (allowed groups)"))
if err != nil {
log.Error().
Caller().
Err(err).
Msg("Failed to write response")
}
return errOIDCAllowedGroups
}
return nil
}
// validateOIDCAllowedUsers checks that if AllowedUsers is provided,
// that the authenticated principal is part of that list.
func validateOIDCAllowedUsers(
writer http.ResponseWriter,
allowedUsers []string,
claims *IDTokenClaims,
) error {
if len(allowedUsers) > 0 &&
!IsStringInSlice(allowedUsers, claims.Email) {
log.Error().Msg("authenticated principal does not match any allowed user")
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusBadRequest)
_, err := writer.Write([]byte("unauthorized principal (user mismatch)"))
if err != nil {
log.Error().
Caller().
Err(err).
Msg("Failed to write response")
}
return errOIDCAllowedUsers
}
return nil
}
// validateMachine retrieves machine information if it exist
// The error is not important, because if it does not
// exist, then this is a new machine and we will move
// on to registration.
func (h *Headscale) validateMachineForOIDCCallback(
writer http.ResponseWriter,
state string,
claims *IDTokenClaims,
expiry time.Time,
) (*key.NodePublic, bool, error) {
// retrieve machinekey from state cache
nodeKeyIf, nodeKeyFound := h.registrationCache.Get(state)
if !nodeKeyFound {
log.Error().
Msg("requested machine state key expired before authorisation completed")
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusBadRequest)
_, err := writer.Write([]byte("state has expired"))
if err != nil {
log.Error().
Caller().
Err(err).
Msg("Failed to write response")
}
return nil, false, errOIDCNodeKeyMissing
}
var nodeKey key.NodePublic
nodeKeyFromCache, nodeKeyOK := nodeKeyIf.(string)
if !nodeKeyOK {
log.Error().
Msg("requested machine state key is not a string")
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusBadRequest)
_, err := writer.Write([]byte("state is invalid"))
if err != nil {
log.Error().
Caller().
Err(err).
Msg("Failed to write response")
}
return nil, false, errOIDCInvalidMachineState
}
err := nodeKey.UnmarshalText(
[]byte(NodePublicKeyEnsurePrefix(nodeKeyFromCache)),
)
if err != nil {
log.Error().
Str("nodeKey", nodeKeyFromCache).
Bool("nodeKeyOK", nodeKeyOK).
Msg("could not parse node public key")
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusBadRequest)
_, werr := writer.Write([]byte("could not parse node public key"))
if werr != nil {
log.Error().
Caller().
Err(werr).
Msg("Failed to write response")
}
return nil, false, err
}
// retrieve machine information if it exist
// The error is not important, because if it does not
// exist, then this is a new machine and we will move
// on to registration.
machine, _ := h.GetMachineByNodeKey(nodeKey)
if machine != nil {
log.Trace().
Caller().
Str("machine", machine.Hostname).
Msg("machine already registered, reauthenticating")
/* cgao6: we'd like to set the expiry from admin console better than due to idtoken
err := h.RefreshMachine(machine, expiry)
if err != nil {
log.Error().
Caller().
Err(err).
Msg("Failed to refresh machine")
http.Error(
writer,
"Failed to refresh machine",
http.StatusInternalServerError,
)
return nil, true, err
}
log.Debug().
Str("machine", machine.Hostname).
Str("expiresAt", fmt.Sprintf("%v", expiry)).
Msg("successfully refreshed machine")
*/
var content bytes.Buffer
if err := oidcCallbackTemplate.Execute(&content, oidcCallbackTemplateConfig{
User: claims.Name,
Verb: "已重认证",
}); err != nil {
log.Error().
Str("func", "OIDCCallback").
Str("type", "reauthenticate").
Err(err).
Msg("Could not render OIDC callback template")
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusInternalServerError)
_, werr := writer.Write([]byte("Could not render OIDC callback template"))
if werr != nil {
log.Error().
Caller().
Err(werr).
Msg("Failed to write response")
}
return nil, true, err
}
writer.Header().Set("Content-Type", "text/html; charset=utf-8")
writer.WriteHeader(http.StatusOK)
_, err = writer.Write(content.Bytes())
if err != nil {
log.Error().
Caller().
Err(err).
Msg("Failed to write response")
}
return nil, true, nil
}
return &nodeKey, false, nil
}
func getUserName(
writer http.ResponseWriter,
claims *IDTokenClaims,
stripEmaildomain bool,
) (string, string, string, error) {
/* cgao6 change to use phone
userName, err := NormalizeToFQDNRules(
claims.Email,
stripEmaildomain,
)
if err != nil {
log.Error().Err(err).Caller().Msgf("couldn't normalize email")
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusInternalServerError)
_, werr := writer.Write([]byte("couldn't normalize email"))
if werr != nil {
log.Error().
Caller().
Err(werr).
Msg("Failed to write response")
}
return "", err
}
*/
userName := strings.ReplaceAll(strings.TrimPrefix(claims.Phone, "+86"), " ", "")
UID := claims.Username
userDisName := claims.Name
return userName, UID, userDisName, nil
}
func (h *Headscale) findOrCreateNewUserForOIDCCallback(
writer http.ResponseWriter,
userName string,
UID string,
userDisName string,
) (*User, error) {
user, err := h.GetUser(userName)
if errors.Is(err, ErrUserNotFound) {
user, err = h.CreateUser(userName, UID, userDisName)
if err != nil {
log.Error().
Err(err).
Caller().
Msgf("could not create new user '%s'", userName)
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusInternalServerError)
_, werr := writer.Write([]byte("could not create user"))
if werr != nil {
log.Error().
Caller().
Err(werr).
Msg("Failed to write response")
}
return nil, err
}
} else if err != nil {
log.Error().
Caller().
Err(err).
Str("user", userName).
Msg("could not find or create user")
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusInternalServerError)
_, werr := writer.Write([]byte("could not find or create user"))
if werr != nil {
log.Error().
Caller().
Err(werr).
Msg("Failed to write response")
}
return nil, err
}
return user, nil
}
func (h *Headscale) registerMachineForOIDCCallback(
writer http.ResponseWriter,
user *User,
nodeKey *key.NodePublic,
expiry time.Time,
) error {
if _, err := h.RegisterMachineFromAuthCallback(
nodeKey.String(),
user.Name,
&expiry,
RegisterMethodOIDC,
); err != nil {
log.Error().
Caller().
Err(err).
Msg("could not register machine")
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusInternalServerError)
_, werr := writer.Write([]byte("could not register machine"))
if werr != nil {
log.Error().
Caller().
Err(werr).
Msg("Failed to write response")
}
return err
}
return nil
}
func renderOIDCCallbackTemplate(
writer http.ResponseWriter,
claims *IDTokenClaims,
) (*bytes.Buffer, error) {
var content bytes.Buffer
if err := oidcCallbackTemplate.Execute(&content, oidcCallbackTemplateConfig{
User: claims.Name,
Verb: "已认证",
}); err != nil {
log.Error().
Str("func", "OIDCCallback").
Str("type", "authenticate").
Err(err).
Msg("Could not render OIDC callback template")
writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
writer.WriteHeader(http.StatusInternalServerError)
_, werr := writer.Write([]byte("Could not render OIDC callback template"))
if werr != nil {
log.Error().
Caller().
Err(werr).
Msg("Failed to write response")
}
return nil, err
}
return &content, nil
}