-
Notifications
You must be signed in to change notification settings - Fork 1.8k
/
auth-pam.c
1391 lines (1246 loc) · 36.2 KB
/
auth-pam.c
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
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/*-
* Copyright (c) 2002 Networks Associates Technology, Inc.
* All rights reserved.
*
* This software was developed for the FreeBSD Project by ThinkSec AS and
* NAI Labs, the Security Research Division of Network Associates, Inc.
* under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
* DARPA CHATS research program.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* Copyright (c) 2003,2004 Damien Miller <djm@mindrot.org>
* Copyright (c) 2003,2004 Darren Tucker <dtucker@zip.com.au>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/* Based on FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des */
#include "includes.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <errno.h>
#include <signal.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifdef USE_PAM
#if defined(HAVE_SECURITY_PAM_APPL_H)
#include <security/pam_appl.h>
#elif defined (HAVE_PAM_PAM_APPL_H)
#include <pam/pam_appl.h>
#endif
#if !defined(SSHD_PAM_SERVICE)
extern char *__progname;
# define SSHD_PAM_SERVICE __progname
#endif
/* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */
#ifdef PAM_SUN_CODEBASE
# define sshpam_const /* Solaris, HP-UX, SunOS */
#else
# define sshpam_const const /* LinuxPAM, OpenPAM, AIX */
#endif
/* Ambiguity in spec: is it an array of pointers or a pointer to an array? */
#ifdef PAM_SUN_CODEBASE
# define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member)
#else
# define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member)
#endif
#include "xmalloc.h"
#include "sshbuf.h"
#include "ssherr.h"
#include "hostfile.h"
#include "auth.h"
#include "auth-pam.h"
#include "canohost.h"
#include "log.h"
#include "msg.h"
#include "packet.h"
#include "misc.h"
#include "servconf.h"
#include "ssh2.h"
#include "auth-options.h"
#include "misc.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
#include "monitor_wrap.h"
extern ServerOptions options;
extern struct sshbuf *loginmsg;
extern u_int utmp_len;
/* so we don't silently change behaviour */
#ifdef USE_POSIX_THREADS
# error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
#endif
/*
* Formerly known as USE_POSIX_THREADS, using this is completely unsupported
* and generally a bad idea. Use at own risk and do not expect support if
* this breaks.
*/
#ifdef UNSUPPORTED_POSIX_THREADS_HACK
#include <pthread.h>
/*
* Avoid namespace clash when *not* using pthreads for systems *with*
* pthreads, which unconditionally define pthread_t via sys/types.h
* (e.g. Linux)
*/
typedef pthread_t sp_pthread_t;
#else
typedef pid_t sp_pthread_t;
#define pthread_exit fake_pthread_exit
#define pthread_create fake_pthread_create
#define pthread_cancel fake_pthread_cancel
#define pthread_join fake_pthread_join
#endif
struct pam_ctxt {
sp_pthread_t pam_thread;
int pam_psock;
int pam_csock;
int pam_done;
};
static void sshpam_free_ctx(void *);
static struct pam_ctxt *cleanup_ctxt;
#ifndef UNSUPPORTED_POSIX_THREADS_HACK
/*
* Simulate threads with processes.
*/
static int sshpam_thread_status = -1;
static sshsig_t sshpam_oldsig;
static void
sshpam_sigchld_handler(int sig)
{
ssh_signal(SIGCHLD, SIG_DFL);
if (cleanup_ctxt == NULL)
return; /* handler called after PAM cleanup, shouldn't happen */
if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
<= 0) {
/* PAM thread has not exitted, privsep slave must have */
kill(cleanup_ctxt->pam_thread, SIGTERM);
while (waitpid(cleanup_ctxt->pam_thread,
&sshpam_thread_status, 0) == -1) {
if (errno == EINTR)
continue;
return;
}
}
if (WIFSIGNALED(sshpam_thread_status) &&
WTERMSIG(sshpam_thread_status) == SIGTERM)
return; /* terminated by pthread_cancel */
if (!WIFEXITED(sshpam_thread_status))
sigdie("PAM: authentication thread exited unexpectedly");
if (WEXITSTATUS(sshpam_thread_status) != 0)
sigdie("PAM: authentication thread exited uncleanly");
}
/* ARGSUSED */
static void
pthread_exit(void *value)
{
_exit(0);
}
/* ARGSUSED */
static int
pthread_create(sp_pthread_t *thread, const void *attr,
void *(*thread_start)(void *), void *arg)
{
pid_t pid;
struct pam_ctxt *ctx = arg;
sshpam_thread_status = -1;
switch ((pid = fork())) {
case -1:
error("fork(): %s", strerror(errno));
return errno;
case 0:
close(ctx->pam_psock);
ctx->pam_psock = -1;
thread_start(arg);
_exit(1);
default:
*thread = pid;
close(ctx->pam_csock);
ctx->pam_csock = -1;
sshpam_oldsig = ssh_signal(SIGCHLD, sshpam_sigchld_handler);
return (0);
}
}
static int
pthread_cancel(sp_pthread_t thread)
{
ssh_signal(SIGCHLD, sshpam_oldsig);
return (kill(thread, SIGTERM));
}
/* ARGSUSED */
static int
pthread_join(sp_pthread_t thread, void **value)
{
int status;
if (sshpam_thread_status != -1)
return (sshpam_thread_status);
ssh_signal(SIGCHLD, sshpam_oldsig);
while (waitpid(thread, &status, 0) == -1) {
if (errno == EINTR)
continue;
fatal("%s: waitpid: %s", __func__, strerror(errno));
}
return (status);
}
#endif
static pam_handle_t *sshpam_handle = NULL;
static int sshpam_err = 0;
static int sshpam_authenticated = 0;
static int sshpam_session_open = 0;
static int sshpam_cred_established = 0;
static int sshpam_account_status = -1;
static int sshpam_maxtries_reached = 0;
static char **sshpam_env = NULL;
static Authctxt *sshpam_authctxt = NULL;
static const char *sshpam_password = NULL;
static char *sshpam_rhost = NULL;
static char *sshpam_laddr = NULL;
static char *sshpam_conninfo = NULL;
/* Some PAM implementations don't implement this */
#ifndef HAVE_PAM_GETENVLIST
static char **
pam_getenvlist(pam_handle_t *pamh)
{
/*
* XXX - If necessary, we can still support environment passing
* for platforms without pam_getenvlist by searching for known
* env vars (e.g. KRB5CCNAME) from the PAM environment.
*/
return NULL;
}
#endif
#ifndef HAVE_PAM_PUTENV
static int
pam_putenv(pam_handle_t *pamh, const char *name_value)
{
return PAM_SUCCESS;
}
#endif /* HAVE_PAM_PUTENV */
/*
* Some platforms, notably Solaris, do not enforce password complexity
* rules during pam_chauthtok() if the real uid of the calling process
* is 0, on the assumption that it's being called by "passwd" run by root.
* This wraps pam_chauthtok and sets/restore the real uid so PAM will do
* the right thing.
*/
#ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
static int
sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
{
int result;
if (sshpam_authctxt == NULL)
fatal("PAM: sshpam_authctxt not initialized");
if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
fatal("%s: setreuid failed: %s", __func__, strerror(errno));
result = pam_chauthtok(pamh, flags);
if (setreuid(0, -1) == -1)
fatal("%s: setreuid failed: %s", __func__, strerror(errno));
return result;
}
# define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b)))
#endif
static void
sshpam_password_change_required(int reqd)
{
extern struct sshauthopt *auth_opts;
static int saved_port, saved_agent, saved_x11;
debug3("%s %d", __func__, reqd);
if (sshpam_authctxt == NULL)
fatal("%s: PAM authctxt not initialized", __func__);
sshpam_authctxt->force_pwchange = reqd;
if (reqd) {
saved_port = auth_opts->permit_port_forwarding_flag;
saved_agent = auth_opts->permit_agent_forwarding_flag;
saved_x11 = auth_opts->permit_x11_forwarding_flag;
auth_opts->permit_port_forwarding_flag = 0;
auth_opts->permit_agent_forwarding_flag = 0;
auth_opts->permit_x11_forwarding_flag = 0;
} else {
if (saved_port)
auth_opts->permit_port_forwarding_flag = saved_port;
if (saved_agent)
auth_opts->permit_agent_forwarding_flag = saved_agent;
if (saved_x11)
auth_opts->permit_x11_forwarding_flag = saved_x11;
}
}
/* Import regular and PAM environment from subprocess */
static void
import_environments(struct sshbuf *b)
{
char *env;
u_int n, i, num_env;
int r;
debug3("PAM: %s entering", __func__);
#ifndef UNSUPPORTED_POSIX_THREADS_HACK
/* Import variables set by do_pam_account */
if ((r = sshbuf_get_u32(b, &n)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (n > INT_MAX)
fatal("%s: invalid PAM account status %u", __func__, n);
sshpam_account_status = (int)n;
if ((r = sshbuf_get_u32(b, &n)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
sshpam_password_change_required(n != 0);
/* Import environment from subprocess */
if ((r = sshbuf_get_u32(b, &num_env)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (num_env > 1024)
fatal("%s: received %u environment variables, expected <= 1024",
__func__, num_env);
sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env));
debug3("PAM: num env strings %d", num_env);
for(i = 0; i < num_env; i++) {
if ((r = sshbuf_get_cstring(b, &(sshpam_env[i]), NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
sshpam_env[num_env] = NULL;
/* Import PAM environment from subprocess */
if ((r = sshbuf_get_u32(b, &num_env)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
debug("PAM: num PAM env strings %d", num_env);
for (i = 0; i < num_env; i++) {
if ((r = sshbuf_get_cstring(b, &env, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
/* Errors are not fatal here */
if ((r = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
error("PAM: pam_putenv: %s",
pam_strerror(sshpam_handle, r));
}
/*
* XXX this possibly leaks env because it is not documented
* what pam_putenv() does with it. Does it copy it? Does it
* take ownweship? We don't know, so it's safest just to leak.
*/
}
#endif
}
/*
* Conversation function for authentication thread.
*/
static int
sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
struct pam_response **resp, void *data)
{
struct sshbuf *buffer;
struct pam_ctxt *ctxt;
struct pam_response *reply;
int r, i;
u_char status;
debug3("PAM: %s entering, %d messages", __func__, n);
*resp = NULL;
if (data == NULL) {
error("PAM: conversation function passed a null context");
return (PAM_CONV_ERR);
}
ctxt = data;
if (n <= 0 || n > PAM_MAX_NUM_MSG)
return (PAM_CONV_ERR);
if ((reply = calloc(n, sizeof(*reply))) == NULL)
return PAM_CONV_ERR;
if ((buffer = sshbuf_new()) == NULL) {
free(reply);
return PAM_CONV_ERR;
}
for (i = 0; i < n; ++i) {
switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
case PAM_PROMPT_ECHO_OFF:
case PAM_PROMPT_ECHO_ON:
if ((r = sshbuf_put_cstring(buffer,
PAM_MSG_MEMBER(msg, i, msg))) != 0)
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
if (ssh_msg_send(ctxt->pam_csock,
PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1)
goto fail;
if (ssh_msg_recv(ctxt->pam_csock, buffer) == -1)
goto fail;
if ((r = sshbuf_get_u8(buffer, &status)) != 0)
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
if (status != PAM_AUTHTOK)
goto fail;
if ((r = sshbuf_get_cstring(buffer,
&reply[i].resp, NULL)) != 0)
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
break;
case PAM_ERROR_MSG:
case PAM_TEXT_INFO:
if ((r = sshbuf_put_cstring(buffer,
PAM_MSG_MEMBER(msg, i, msg))) != 0)
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
if (ssh_msg_send(ctxt->pam_csock,
PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1)
goto fail;
break;
default:
goto fail;
}
sshbuf_reset(buffer);
}
sshbuf_free(buffer);
*resp = reply;
return (PAM_SUCCESS);
fail:
for(i = 0; i < n; i++) {
free(reply[i].resp);
}
free(reply);
sshbuf_free(buffer);
return (PAM_CONV_ERR);
}
/*
* Authentication thread.
*/
static void *
sshpam_thread(void *ctxtp)
{
struct pam_ctxt *ctxt = ctxtp;
struct sshbuf *buffer = NULL;
struct pam_conv sshpam_conv;
int r, flags = (options.permit_empty_passwd == 0 ?
PAM_DISALLOW_NULL_AUTHTOK : 0);
#ifndef UNSUPPORTED_POSIX_THREADS_HACK
extern char **environ;
char **env_from_pam;
u_int i;
const char *pam_user;
const char **ptr_pam_user = &pam_user;
char *tz = getenv("TZ");
sshpam_err = pam_get_item(sshpam_handle, PAM_USER,
(sshpam_const void **)ptr_pam_user);
if (sshpam_err != PAM_SUCCESS)
goto auth_fail;
environ[0] = NULL;
if (tz != NULL)
if (setenv("TZ", tz, 1) == -1)
error("PAM: could not set TZ environment: %s",
strerror(errno));
if (sshpam_authctxt != NULL) {
setproctitle("%s [pam]",
sshpam_authctxt->valid ? pam_user : "unknown");
}
#endif
sshpam_conv.conv = sshpam_thread_conv;
sshpam_conv.appdata_ptr = ctxt;
if (sshpam_authctxt == NULL)
fatal("%s: PAM authctxt not initialized", __func__);
if ((buffer = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
(const void *)&sshpam_conv);
if (sshpam_err != PAM_SUCCESS)
goto auth_fail;
sshpam_err = pam_authenticate(sshpam_handle, flags);
if (sshpam_err == PAM_MAXTRIES)
sshpam_set_maxtries_reached(1);
if (sshpam_err != PAM_SUCCESS)
goto auth_fail;
if (!do_pam_account()) {
sshpam_err = PAM_ACCT_EXPIRED;
goto auth_fail;
}
if (sshpam_authctxt->force_pwchange) {
sshpam_err = pam_chauthtok(sshpam_handle,
PAM_CHANGE_EXPIRED_AUTHTOK);
if (sshpam_err != PAM_SUCCESS)
goto auth_fail;
sshpam_password_change_required(0);
}
if ((r = sshbuf_put_cstring(buffer, "OK")) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
#ifndef UNSUPPORTED_POSIX_THREADS_HACK
/* Export variables set by do_pam_account */
if ((r = sshbuf_put_u32(buffer, sshpam_account_status)) != 0 ||
(r = sshbuf_put_u32(buffer, sshpam_authctxt->force_pwchange)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
/* Export any environment strings set in child */
for (i = 0; environ[i] != NULL; i++) {
/* Count */
if (i > INT_MAX)
fatal("%s: too many environment strings", __func__);
}
if ((r = sshbuf_put_u32(buffer, i)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
for (i = 0; environ[i] != NULL; i++) {
if ((r = sshbuf_put_cstring(buffer, environ[i])) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
/* Export any environment strings set by PAM in child */
env_from_pam = pam_getenvlist(sshpam_handle);
for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) {
/* Count */
if (i > INT_MAX)
fatal("%s: too many PAM environment strings", __func__);
}
if ((r = sshbuf_put_u32(buffer, i)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) {
if ((r = sshbuf_put_cstring(buffer, env_from_pam[i])) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
#endif /* UNSUPPORTED_POSIX_THREADS_HACK */
/* XXX - can't do much about an error here */
ssh_msg_send(ctxt->pam_csock, sshpam_err, buffer);
sshbuf_free(buffer);
pthread_exit(NULL);
auth_fail:
if ((r = sshbuf_put_cstring(buffer,
pam_strerror(sshpam_handle, sshpam_err))) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
/* XXX - can't do much about an error here */
if (sshpam_err == PAM_ACCT_EXPIRED)
ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, buffer);
else if (sshpam_maxtries_reached)
ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, buffer);
else
ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, buffer);
sshbuf_free(buffer);
pthread_exit(NULL);
return (NULL); /* Avoid warning for non-pthread case */
}
void
sshpam_thread_cleanup(void)
{
struct pam_ctxt *ctxt = cleanup_ctxt;
debug3("PAM: %s entering", __func__);
if (ctxt != NULL && ctxt->pam_thread != 0) {
pthread_cancel(ctxt->pam_thread);
pthread_join(ctxt->pam_thread, NULL);
close(ctxt->pam_psock);
close(ctxt->pam_csock);
memset(ctxt, 0, sizeof(*ctxt));
cleanup_ctxt = NULL;
}
}
static int
sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
struct pam_response **resp, void *data)
{
debug3("PAM: %s entering, %d messages", __func__, n);
return (PAM_CONV_ERR);
}
static struct pam_conv null_conv = { sshpam_null_conv, NULL };
static int
sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
struct pam_response **resp, void *data)
{
struct pam_response *reply;
int r, i;
debug3("PAM: %s called with %d messages", __func__, n);
*resp = NULL;
if (n <= 0 || n > PAM_MAX_NUM_MSG)
return (PAM_CONV_ERR);
if ((reply = calloc(n, sizeof(*reply))) == NULL)
return (PAM_CONV_ERR);
for (i = 0; i < n; ++i) {
switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
case PAM_ERROR_MSG:
case PAM_TEXT_INFO:
if ((r = sshbuf_putf(loginmsg, "%s\n",
PAM_MSG_MEMBER(msg, i, msg))) != 0)
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
reply[i].resp_retcode = PAM_SUCCESS;
break;
default:
goto fail;
}
}
*resp = reply;
return (PAM_SUCCESS);
fail:
for(i = 0; i < n; i++) {
free(reply[i].resp);
}
free(reply);
return (PAM_CONV_ERR);
}
static struct pam_conv store_conv = { sshpam_store_conv, NULL };
void
sshpam_cleanup(void)
{
if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor()))
return;
debug("PAM: cleanup");
pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
if (sshpam_session_open) {
debug("PAM: closing session");
pam_close_session(sshpam_handle, PAM_SILENT);
sshpam_session_open = 0;
}
if (sshpam_cred_established) {
debug("PAM: deleting credentials");
pam_setcred(sshpam_handle, PAM_DELETE_CRED);
sshpam_cred_established = 0;
}
sshpam_authenticated = 0;
pam_end(sshpam_handle, sshpam_err);
sshpam_handle = NULL;
}
static int
sshpam_init(struct ssh *ssh, Authctxt *authctxt)
{
const char *pam_user, *user = authctxt->user;
const char **ptr_pam_user = &pam_user;
if (sshpam_handle == NULL) {
if (ssh == NULL) {
fatal("%s: called initially with no "
"packet context", __func__);
}
} if (sshpam_handle != NULL) {
/* We already have a PAM context; check if the user matches */
sshpam_err = pam_get_item(sshpam_handle,
PAM_USER, (sshpam_const void **)ptr_pam_user);
if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
return (0);
pam_end(sshpam_handle, sshpam_err);
sshpam_handle = NULL;
}
debug("PAM: initializing for \"%s\"", user);
sshpam_err =
pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
sshpam_authctxt = authctxt;
if (sshpam_err != PAM_SUCCESS) {
pam_end(sshpam_handle, sshpam_err);
sshpam_handle = NULL;
return (-1);
}
if (ssh != NULL && sshpam_rhost == NULL) {
/*
* We need to cache these as we don't have packet context
* during the kbdint flow.
*/
sshpam_rhost = xstrdup(auth_get_canonical_hostname(ssh,
options.use_dns));
sshpam_laddr = get_local_ipaddr(
ssh_packet_get_connection_in(ssh));
xasprintf(&sshpam_conninfo, "SSH_CONNECTION=%.50s %d %.50s %d",
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
sshpam_laddr, ssh_local_port(ssh));
}
if (sshpam_rhost != NULL) {
debug("PAM: setting PAM_RHOST to \"%s\"", sshpam_rhost);
sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST,
sshpam_rhost);
if (sshpam_err != PAM_SUCCESS) {
pam_end(sshpam_handle, sshpam_err);
sshpam_handle = NULL;
return (-1);
}
/* Put SSH_CONNECTION in the PAM environment too */
pam_putenv(sshpam_handle, sshpam_conninfo);
}
#ifdef PAM_TTY_KLUDGE
/*
* Some silly PAM modules (e.g. pam_time) require a TTY to operate.
* sshd doesn't set the tty until too late in the auth process and
* may not even set one (for tty-less connections)
*/
debug("PAM: setting PAM_TTY to \"ssh\"");
sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
if (sshpam_err != PAM_SUCCESS) {
pam_end(sshpam_handle, sshpam_err);
sshpam_handle = NULL;
return (-1);
}
#endif
return (0);
}
static void
expose_authinfo(const char *caller)
{
char *auth_info;
/*
* Expose authentication information to PAM.
* The environment variable is versioned. Please increment the
* version suffix if the format of session_info changes.
*/
if (sshpam_authctxt->session_info == NULL)
auth_info = xstrdup("");
else if ((auth_info = sshbuf_dup_string(
sshpam_authctxt->session_info)) == NULL)
fatal("%s: sshbuf_dup_string failed", __func__);
debug2("%s: auth information in SSH_AUTH_INFO_0", caller);
do_pam_putenv("SSH_AUTH_INFO_0", auth_info);
free(auth_info);
}
static void *
sshpam_init_ctx(Authctxt *authctxt)
{
struct pam_ctxt *ctxt;
int result, socks[2];
debug3("PAM: %s entering", __func__);
/*
* Refuse to start if we don't have PAM enabled or do_pam_account
* has previously failed.
*/
if (!options.use_pam || sshpam_account_status == 0)
return NULL;
/* Initialize PAM */
if (sshpam_init(NULL, authctxt) == -1) {
error("PAM: initialization failed");
return (NULL);
}
expose_authinfo(__func__);
ctxt = xcalloc(1, sizeof *ctxt);
/* Start the authentication thread */
if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
error("PAM: failed create sockets: %s", strerror(errno));
free(ctxt);
return (NULL);
}
ctxt->pam_psock = socks[0];
ctxt->pam_csock = socks[1];
result = pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt);
if (result != 0) {
error("PAM: failed to start authentication thread: %s",
strerror(result));
close(socks[0]);
close(socks[1]);
free(ctxt);
return (NULL);
}
cleanup_ctxt = ctxt;
return (ctxt);
}
static int
sshpam_query(void *ctx, char **name, char **info,
u_int *num, char ***prompts, u_int **echo_on)
{
struct sshbuf *buffer;
struct pam_ctxt *ctxt = ctx;
size_t plen;
u_char type;
char *msg;
size_t len, mlen;
int r;
debug3("PAM: %s entering", __func__);
if ((buffer = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
*name = xstrdup("");
*info = xstrdup("");
*prompts = xmalloc(sizeof(char *));
**prompts = NULL;
plen = 0;
*echo_on = xmalloc(sizeof(u_int));
while (ssh_msg_recv(ctxt->pam_psock, buffer) == 0) {
if ((r = sshbuf_get_u8(buffer, &type)) != 0 ||
(r = sshbuf_get_cstring(buffer, &msg, &mlen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
switch (type) {
case PAM_PROMPT_ECHO_ON:
case PAM_PROMPT_ECHO_OFF:
*num = 1;
len = plen + mlen + 1;
**prompts = xreallocarray(**prompts, 1, len);
strlcpy(**prompts + plen, msg, len - plen);
plen += mlen;
**echo_on = (type == PAM_PROMPT_ECHO_ON);
free(msg);
sshbuf_free(buffer);
return (0);
case PAM_ERROR_MSG:
case PAM_TEXT_INFO:
/* accumulate messages */
len = plen + mlen + 2;
**prompts = xreallocarray(**prompts, 1, len);
strlcpy(**prompts + plen, msg, len - plen);
plen += mlen;
strlcat(**prompts + plen, "\n", len - plen);
plen++;
free(msg);
break;
case PAM_ACCT_EXPIRED:
case PAM_MAXTRIES:
if (type == PAM_ACCT_EXPIRED)
sshpam_account_status = 0;
if (type == PAM_MAXTRIES)
sshpam_set_maxtries_reached(1);
/* FALLTHROUGH */
case PAM_AUTH_ERR:
debug3("PAM: %s", pam_strerror(sshpam_handle, type));
if (**prompts != NULL && strlen(**prompts) != 0) {
*info = **prompts;
**prompts = NULL;
*num = 0;
**echo_on = 0;
ctxt->pam_done = -1;
free(msg);
sshbuf_free(buffer);
return 0;
}
/* FALLTHROUGH */
case PAM_SUCCESS:
if (**prompts != NULL) {
/* drain any accumulated messages */
debug("PAM: %s", **prompts);
if ((r = sshbuf_put(loginmsg, **prompts,
strlen(**prompts))) != 0)
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
free(**prompts);
**prompts = NULL;
}
if (type == PAM_SUCCESS) {
if (!sshpam_authctxt->valid ||
(sshpam_authctxt->pw->pw_uid == 0 &&
options.permit_root_login != PERMIT_YES))
fatal("Internal error: PAM auth "
"succeeded when it should have "
"failed");
import_environments(buffer);
*num = 0;
**echo_on = 0;
ctxt->pam_done = 1;
free(msg);
sshbuf_free(buffer);
return (0);
}
error("PAM: %s for %s%.100s from %.100s", msg,
sshpam_authctxt->valid ? "" : "illegal user ",
sshpam_authctxt->user, sshpam_rhost);
/* FALLTHROUGH */
default:
*num = 0;
**echo_on = 0;
free(msg);
ctxt->pam_done = -1;
sshbuf_free(buffer);
return (-1);
}
}
sshbuf_free(buffer);
return (-1);
}
/*
* Returns a junk password of identical length to that the user supplied.
* Used to mitigate timing attacks against crypt(3)/PAM stacks that
* vary processing time in proportion to password length.
*/
static char *
fake_password(const char *wire_password)
{
const char junk[] = "\b\n\r\177INCORRECT";
char *ret = NULL;
size_t i, l = wire_password != NULL ? strlen(wire_password) : 0;
if (l >= INT_MAX)
fatal("%s: password length too long: %zu", __func__, l);
ret = malloc(l + 1);
if (ret == NULL)
return NULL;
for (i = 0; i < l; i++)
ret[i] = junk[i % (sizeof(junk) - 1)];
ret[i] = '\0';
return ret;
}
/* XXX - see also comment in auth-chall.c:verify_response */
static int
sshpam_respond(void *ctx, u_int num, char **resp)
{
struct sshbuf *buffer;
struct pam_ctxt *ctxt = ctx;
char *fake;
int r;
debug2("PAM: %s entering, %u responses", __func__, num);
switch (ctxt->pam_done) {
case 1:
sshpam_authenticated = 1;
return (0);
case 0:
break;
default:
return (-1);
}
if (num != 1) {
error("PAM: expected one response, got %u", num);
return (-1);
}
if ((buffer = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if (sshpam_authctxt->valid &&
(sshpam_authctxt->pw->pw_uid != 0 ||
options.permit_root_login == PERMIT_YES)) {
if ((r = sshbuf_put_cstring(buffer, *resp)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
} else {
fake = fake_password(*resp);
if ((r = sshbuf_put_cstring(buffer, fake)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
free(fake);
}
if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, buffer) == -1) {
sshbuf_free(buffer);
return (-1);
}
sshbuf_free(buffer);