OpenSSH: Revert few local modifications.
[dragonfly.git] / crypto / openssh / auth-pam.c
CommitLineData
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1/*-
2 * Copyright (c) 2002 Networks Associates Technology, Inc.
3 * All rights reserved.
4 *
5 * This software was developed for the FreeBSD Project by ThinkSec AS and
6 * NAI Labs, the Security Research Division of Network Associates, Inc.
7 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
8 * DARPA CHATS research program.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31/*
32 * Copyright (c) 2003,2004 Damien Miller <djm@mindrot.org>
33 * Copyright (c) 2003,2004 Darren Tucker <dtucker@zip.com.au>
34 *
35 * Permission to use, copy, modify, and distribute this software for any
36 * purpose with or without fee is hereby granted, provided that the above
37 * copyright notice and this permission notice appear in all copies.
38 *
39 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
40 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
41 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
42 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
43 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
44 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
45 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
46 */
47
e9778795
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48/* Based on FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des */
49
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50#include "includes.h"
51
52#include <sys/types.h>
53#include <sys/stat.h>
54#include <sys/wait.h>
55
56#include <errno.h>
57#include <signal.h>
58#include <stdarg.h>
59#include <string.h>
60#include <unistd.h>
61
62#ifdef USE_PAM
63#if defined(HAVE_SECURITY_PAM_APPL_H)
64#include <security/pam_appl.h>
65#elif defined (HAVE_PAM_PAM_APPL_H)
66#include <pam/pam_appl.h>
67#endif
68
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69#if !defined(SSHD_PAM_SERVICE)
70extern char *__progname;
71# define SSHD_PAM_SERVICE __progname
72#endif
73
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74/* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */
75#ifdef PAM_SUN_CODEBASE
e9778795 76# define sshpam_const /* Solaris, HP-UX, SunOS */
16c343f1 77#else
e9778795 78# define sshpam_const const /* LinuxPAM, OpenPAM, AIX */
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79#endif
80
81/* Ambiguity in spec: is it an array of pointers or a pointer to an array? */
82#ifdef PAM_SUN_CODEBASE
83# define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member)
84#else
85# define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member)
86#endif
87
88#include "xmalloc.h"
89#include "buffer.h"
90#include "key.h"
91#include "hostfile.h"
92#include "auth.h"
93#include "auth-pam.h"
94#include "canohost.h"
95#include "log.h"
96#include "msg.h"
97#include "packet.h"
98#include "misc.h"
99#include "servconf.h"
100#include "ssh2.h"
101#include "auth-options.h"
102#ifdef GSSAPI
103#include "ssh-gss.h"
104#endif
105#include "monitor_wrap.h"
106
107extern ServerOptions options;
108extern Buffer loginmsg;
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109extern u_int utmp_len;
110
111/* so we don't silently change behaviour */
112#ifdef USE_POSIX_THREADS
113# error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
114#endif
115
116/*
117 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
118 * and generally a bad idea. Use at own risk and do not expect support if
119 * this breaks.
120 */
121#ifdef UNSUPPORTED_POSIX_THREADS_HACK
122#include <pthread.h>
123/*
124 * Avoid namespace clash when *not* using pthreads for systems *with*
125 * pthreads, which unconditionally define pthread_t via sys/types.h
126 * (e.g. Linux)
127 */
128typedef pthread_t sp_pthread_t;
129#else
130typedef pid_t sp_pthread_t;
131#endif
132
133struct pam_ctxt {
134 sp_pthread_t pam_thread;
135 int pam_psock;
136 int pam_csock;
137 int pam_done;
138};
139
140static void sshpam_free_ctx(void *);
141static struct pam_ctxt *cleanup_ctxt;
142
143#ifndef UNSUPPORTED_POSIX_THREADS_HACK
144/*
145 * Simulate threads with processes.
146 */
147
148static int sshpam_thread_status = -1;
149static mysig_t sshpam_oldsig;
150
151static void
152sshpam_sigchld_handler(int sig)
153{
154 signal(SIGCHLD, SIG_DFL);
155 if (cleanup_ctxt == NULL)
156 return; /* handler called after PAM cleanup, shouldn't happen */
157 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
158 <= 0) {
159 /* PAM thread has not exitted, privsep slave must have */
160 kill(cleanup_ctxt->pam_thread, SIGTERM);
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161 while (waitpid(cleanup_ctxt->pam_thread,
162 &sshpam_thread_status, 0) == -1) {
163 if (errno == EINTR)
164 continue;
165 return;
166 }
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167 }
168 if (WIFSIGNALED(sshpam_thread_status) &&
169 WTERMSIG(sshpam_thread_status) == SIGTERM)
170 return; /* terminated by pthread_cancel */
171 if (!WIFEXITED(sshpam_thread_status))
172 sigdie("PAM: authentication thread exited unexpectedly");
173 if (WEXITSTATUS(sshpam_thread_status) != 0)
174 sigdie("PAM: authentication thread exited uncleanly");
175}
176
177/* ARGSUSED */
178static void
179pthread_exit(void *value)
180{
181 _exit(0);
182}
183
184/* ARGSUSED */
185static int
186pthread_create(sp_pthread_t *thread, const void *attr,
187 void *(*thread_start)(void *), void *arg)
188{
189 pid_t pid;
190 struct pam_ctxt *ctx = arg;
191
192 sshpam_thread_status = -1;
193 switch ((pid = fork())) {
194 case -1:
195 error("fork(): %s", strerror(errno));
196 return (-1);
197 case 0:
198 close(ctx->pam_psock);
199 ctx->pam_psock = -1;
200 thread_start(arg);
201 _exit(1);
202 default:
203 *thread = pid;
204 close(ctx->pam_csock);
205 ctx->pam_csock = -1;
206 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
207 return (0);
208 }
209}
210
211static int
212pthread_cancel(sp_pthread_t thread)
213{
214 signal(SIGCHLD, sshpam_oldsig);
215 return (kill(thread, SIGTERM));
216}
217
218/* ARGSUSED */
219static int
220pthread_join(sp_pthread_t thread, void **value)
221{
222 int status;
223
224 if (sshpam_thread_status != -1)
225 return (sshpam_thread_status);
226 signal(SIGCHLD, sshpam_oldsig);
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227 while (waitpid(thread, &status, 0) == -1) {
228 if (errno == EINTR)
229 continue;
230 fatal("%s: waitpid: %s", __func__, strerror(errno));
231 }
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232 return (status);
233}
234#endif
235
236
237static pam_handle_t *sshpam_handle = NULL;
238static int sshpam_err = 0;
239static int sshpam_authenticated = 0;
240static int sshpam_session_open = 0;
241static int sshpam_cred_established = 0;
242static int sshpam_account_status = -1;
e9778795 243static int sshpam_maxtries_reached = 0;
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244static char **sshpam_env = NULL;
245static Authctxt *sshpam_authctxt = NULL;
246static const char *sshpam_password = NULL;
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247
248/* Some PAM implementations don't implement this */
249#ifndef HAVE_PAM_GETENVLIST
250static char **
251pam_getenvlist(pam_handle_t *pamh)
252{
253 /*
254 * XXX - If necessary, we can still support envrionment passing
255 * for platforms without pam_getenvlist by searching for known
256 * env vars (e.g. KRB5CCNAME) from the PAM environment.
257 */
258 return NULL;
259}
260#endif
261
262/*
263 * Some platforms, notably Solaris, do not enforce password complexity
264 * rules during pam_chauthtok() if the real uid of the calling process
265 * is 0, on the assumption that it's being called by "passwd" run by root.
266 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
267 * the right thing.
268 */
269#ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
270static int
271sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
272{
273 int result;
274
275 if (sshpam_authctxt == NULL)
276 fatal("PAM: sshpam_authctxt not initialized");
277 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
278 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
279 result = pam_chauthtok(pamh, flags);
280 if (setreuid(0, -1) == -1)
281 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
282 return result;
283}
284# define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b)))
285#endif
286
a4a3adb1 287void
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288sshpam_password_change_required(int reqd)
289{
290 debug3("%s %d", __func__, reqd);
291 if (sshpam_authctxt == NULL)
292 fatal("%s: PAM authctxt not initialized", __func__);
293 sshpam_authctxt->force_pwchange = reqd;
294 if (reqd) {
295 no_port_forwarding_flag |= 2;
296 no_agent_forwarding_flag |= 2;
297 no_x11_forwarding_flag |= 2;
298 } else {
299 no_port_forwarding_flag &= ~2;
300 no_agent_forwarding_flag &= ~2;
301 no_x11_forwarding_flag &= ~2;
302 }
303}
304
305/* Import regular and PAM environment from subprocess */
306static void
307import_environments(Buffer *b)
308{
309 char *env;
310 u_int i, num_env;
311 int err;
312
313 debug3("PAM: %s entering", __func__);
314
315#ifndef UNSUPPORTED_POSIX_THREADS_HACK
316 /* Import variables set by do_pam_account */
317 sshpam_account_status = buffer_get_int(b);
318 sshpam_password_change_required(buffer_get_int(b));
319
320 /* Import environment from subprocess */
321 num_env = buffer_get_int(b);
322 if (num_env > 1024)
323 fatal("%s: received %u environment variables, expected <= 1024",
324 __func__, num_env);
325 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env));
326 debug3("PAM: num env strings %d", num_env);
327 for(i = 0; i < num_env; i++)
328 sshpam_env[i] = buffer_get_string(b, NULL);
329
330 sshpam_env[num_env] = NULL;
331
332 /* Import PAM environment from subprocess */
333 num_env = buffer_get_int(b);
334 debug("PAM: num PAM env strings %d", num_env);
335 for(i = 0; i < num_env; i++) {
336 env = buffer_get_string(b, NULL);
337
338#ifdef HAVE_PAM_PUTENV
339 /* Errors are not fatal here */
340 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
341 error("PAM: pam_putenv: %s",
342 pam_strerror(sshpam_handle, sshpam_err));
343 }
344#endif
345 }
346#endif
347}
348
349/*
350 * Conversation function for authentication thread.
351 */
352static int
353sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
354 struct pam_response **resp, void *data)
355{
356 Buffer buffer;
357 struct pam_ctxt *ctxt;
358 struct pam_response *reply;
359 int i;
360
361 debug3("PAM: %s entering, %d messages", __func__, n);
362 *resp = NULL;
363
364 if (data == NULL) {
365 error("PAM: conversation function passed a null context");
366 return (PAM_CONV_ERR);
367 }
368 ctxt = data;
369 if (n <= 0 || n > PAM_MAX_NUM_MSG)
370 return (PAM_CONV_ERR);
371
372 if ((reply = calloc(n, sizeof(*reply))) == NULL)
373 return (PAM_CONV_ERR);
374
375 buffer_init(&buffer);
376 for (i = 0; i < n; ++i) {
377 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
378 case PAM_PROMPT_ECHO_OFF:
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379 case PAM_PROMPT_ECHO_ON:
380 buffer_put_cstring(&buffer,
381 PAM_MSG_MEMBER(msg, i, msg));
382 if (ssh_msg_send(ctxt->pam_csock,
383 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
384 goto fail;
385 if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
386 goto fail;
387 if (buffer_get_char(&buffer) != PAM_AUTHTOK)
388 goto fail;
389 reply[i].resp = buffer_get_string(&buffer, NULL);
390 break;
391 case PAM_ERROR_MSG:
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392 case PAM_TEXT_INFO:
393 buffer_put_cstring(&buffer,
394 PAM_MSG_MEMBER(msg, i, msg));
395 if (ssh_msg_send(ctxt->pam_csock,
396 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
397 goto fail;
398 break;
399 default:
400 goto fail;
401 }
402 buffer_clear(&buffer);
403 }
404 buffer_free(&buffer);
405 *resp = reply;
406 return (PAM_SUCCESS);
407
408 fail:
409 for(i = 0; i < n; i++) {
36e94dc5 410 free(reply[i].resp);
16c343f1 411 }
36e94dc5 412 free(reply);
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PA
413 buffer_free(&buffer);
414 return (PAM_CONV_ERR);
415}
416
417/*
418 * Authentication thread.
419 */
420static void *
421sshpam_thread(void *ctxtp)
422{
423 struct pam_ctxt *ctxt = ctxtp;
424 Buffer buffer;
425 struct pam_conv sshpam_conv;
426 int flags = (options.permit_empty_passwd == 0 ?
427 PAM_DISALLOW_NULL_AUTHTOK : 0);
428#ifndef UNSUPPORTED_POSIX_THREADS_HACK
429 extern char **environ;
430 char **env_from_pam;
431 u_int i;
432 const char *pam_user;
433 const char **ptr_pam_user = &pam_user;
434 char *tz = getenv("TZ");
435
36e94dc5 436 sshpam_err = pam_get_item(sshpam_handle, PAM_USER,
16c343f1 437 (sshpam_const void **)ptr_pam_user);
36e94dc5
PA
438 if (sshpam_err != PAM_SUCCESS)
439 goto auth_fail;
16c343f1
PA
440
441 environ[0] = NULL;
442 if (tz != NULL)
443 if (setenv("TZ", tz, 1) == -1)
444 error("PAM: could not set TZ environment: %s",
445 strerror(errno));
446
447 if (sshpam_authctxt != NULL) {
448 setproctitle("%s [pam]",
449 sshpam_authctxt->valid ? pam_user : "unknown");
450 }
451#endif
452
453 sshpam_conv.conv = sshpam_thread_conv;
454 sshpam_conv.appdata_ptr = ctxt;
455
456 if (sshpam_authctxt == NULL)
457 fatal("%s: PAM authctxt not initialized", __func__);
458
459 buffer_init(&buffer);
460 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
461 (const void *)&sshpam_conv);
462 if (sshpam_err != PAM_SUCCESS)
463 goto auth_fail;
464 sshpam_err = pam_authenticate(sshpam_handle, flags);
e9778795
PA
465 if (sshpam_err == PAM_MAXTRIES)
466 sshpam_set_maxtries_reached(1);
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PA
467 if (sshpam_err != PAM_SUCCESS)
468 goto auth_fail;
469
2c9c1408
MD
470 if (!do_pam_account()) {
471 sshpam_err = PAM_ACCT_EXPIRED;
472 goto auth_fail;
473 }
474 if (sshpam_authctxt->force_pwchange) {
475 sshpam_err = pam_chauthtok(sshpam_handle,
476 PAM_CHANGE_EXPIRED_AUTHTOK);
477 if (sshpam_err != PAM_SUCCESS)
16c343f1 478 goto auth_fail;
2c9c1408 479 sshpam_password_change_required(0);
16c343f1
PA
480 }
481
482 buffer_put_cstring(&buffer, "OK");
483
484#ifndef UNSUPPORTED_POSIX_THREADS_HACK
485 /* Export variables set by do_pam_account */
486 buffer_put_int(&buffer, sshpam_account_status);
487 buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);
488
489 /* Export any environment strings set in child */
490 for(i = 0; environ[i] != NULL; i++)
491 ; /* Count */
492 buffer_put_int(&buffer, i);
493 for(i = 0; environ[i] != NULL; i++)
494 buffer_put_cstring(&buffer, environ[i]);
495
496 /* Export any environment strings set by PAM in child */
497 env_from_pam = pam_getenvlist(sshpam_handle);
498 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
499 ; /* Count */
500 buffer_put_int(&buffer, i);
501 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
502 buffer_put_cstring(&buffer, env_from_pam[i]);
503#endif /* UNSUPPORTED_POSIX_THREADS_HACK */
504
505 /* XXX - can't do much about an error here */
506 ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
507 buffer_free(&buffer);
508 pthread_exit(NULL);
509
510 auth_fail:
511 buffer_put_cstring(&buffer,
512 pam_strerror(sshpam_handle, sshpam_err));
513 /* XXX - can't do much about an error here */
514 if (sshpam_err == PAM_ACCT_EXPIRED)
515 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, &buffer);
e9778795
PA
516 else if (sshpam_maxtries_reached)
517 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, &buffer);
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518 else
519 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
520 buffer_free(&buffer);
521 pthread_exit(NULL);
522
523 return (NULL); /* Avoid warning for non-pthread case */
524}
525
526void
527sshpam_thread_cleanup(void)
528{
529 struct pam_ctxt *ctxt = cleanup_ctxt;
530
531 debug3("PAM: %s entering", __func__);
532 if (ctxt != NULL && ctxt->pam_thread != 0) {
533 pthread_cancel(ctxt->pam_thread);
534 pthread_join(ctxt->pam_thread, NULL);
535 close(ctxt->pam_psock);
536 close(ctxt->pam_csock);
537 memset(ctxt, 0, sizeof(*ctxt));
538 cleanup_ctxt = NULL;
539 }
540}
541
542static int
543sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
544 struct pam_response **resp, void *data)
545{
546 debug3("PAM: %s entering, %d messages", __func__, n);
547 return (PAM_CONV_ERR);
548}
549
550static struct pam_conv null_conv = { sshpam_null_conv, NULL };
551
552static int
553sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
554 struct pam_response **resp, void *data)
555{
556 struct pam_response *reply;
557 int i;
558 size_t len;
559
560 debug3("PAM: %s called with %d messages", __func__, n);
561 *resp = NULL;
562
563 if (n <= 0 || n > PAM_MAX_NUM_MSG)
564 return (PAM_CONV_ERR);
565
566 if ((reply = calloc(n, sizeof(*reply))) == NULL)
567 return (PAM_CONV_ERR);
568
569 for (i = 0; i < n; ++i) {
570 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
571 case PAM_ERROR_MSG:
572 case PAM_TEXT_INFO:
573 len = strlen(PAM_MSG_MEMBER(msg, i, msg));
574 buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
575 buffer_append(&loginmsg, "\n", 1 );
576 reply[i].resp_retcode = PAM_SUCCESS;
577 break;
578 default:
579 goto fail;
580 }
581 }
582 *resp = reply;
583 return (PAM_SUCCESS);
584
585 fail:
586 for(i = 0; i < n; i++) {
36e94dc5 587 free(reply[i].resp);
16c343f1 588 }
36e94dc5 589 free(reply);
16c343f1
PA
590 return (PAM_CONV_ERR);
591}
592
593static struct pam_conv store_conv = { sshpam_store_conv, NULL };
594
595void
596sshpam_cleanup(void)
597{
598 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor()))
599 return;
600 debug("PAM: cleanup");
601 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
16c343f1
PA
602 if (sshpam_session_open) {
603 debug("PAM: closing session");
604 pam_close_session(sshpam_handle, PAM_SILENT);
605 sshpam_session_open = 0;
606 }
40c002af
PA
607 if (sshpam_cred_established) {
608 debug("PAM: deleting credentials");
609 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
610 sshpam_cred_established = 0;
611 }
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612 sshpam_authenticated = 0;
613 pam_end(sshpam_handle, sshpam_err);
614 sshpam_handle = NULL;
615}
616
617static int
618sshpam_init(Authctxt *authctxt)
619{
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620 const char *pam_rhost, *pam_user, *user = authctxt->user;
621 const char **ptr_pam_user = &pam_user;
e9778795 622 struct ssh *ssh = active_state; /* XXX */
16c343f1
PA
623
624 if (sshpam_handle != NULL) {
625 /* We already have a PAM context; check if the user matches */
626 sshpam_err = pam_get_item(sshpam_handle,
627 PAM_USER, (sshpam_const void **)ptr_pam_user);
628 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
629 return (0);
630 pam_end(sshpam_handle, sshpam_err);
631 sshpam_handle = NULL;
632 }
633 debug("PAM: initializing for \"%s\"", user);
634 sshpam_err =
635 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
636 sshpam_authctxt = authctxt;
637
638 if (sshpam_err != PAM_SUCCESS) {
639 pam_end(sshpam_handle, sshpam_err);
640 sshpam_handle = NULL;
641 return (-1);
642 }
e9778795 643 pam_rhost = auth_get_canonical_hostname(ssh, options.use_dns);
16c343f1
PA
644 debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
645 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
646 if (sshpam_err != PAM_SUCCESS) {
647 pam_end(sshpam_handle, sshpam_err);
648 sshpam_handle = NULL;
649 return (-1);
650 }
651#ifdef PAM_TTY_KLUDGE
652 /*
653 * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
654 * sshd doesn't set the tty until too late in the auth process and
655 * may not even set one (for tty-less connections)
656 */
657 debug("PAM: setting PAM_TTY to \"ssh\"");
658 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
659 if (sshpam_err != PAM_SUCCESS) {
660 pam_end(sshpam_handle, sshpam_err);
661 sshpam_handle = NULL;
662 return (-1);
663 }
664#endif
665 return (0);
666}
667
668static void *
669sshpam_init_ctx(Authctxt *authctxt)
670{
671 struct pam_ctxt *ctxt;
672 int socks[2];
673
674 debug3("PAM: %s entering", __func__);
675 /*
676 * Refuse to start if we don't have PAM enabled or do_pam_account
677 * has previously failed.
678 */
679 if (!options.use_pam || sshpam_account_status == 0)
680 return NULL;
681
682 /* Initialize PAM */
683 if (sshpam_init(authctxt) == -1) {
684 error("PAM: initialization failed");
685 return (NULL);
686 }
687
688 ctxt = xcalloc(1, sizeof *ctxt);
689
690 /* Start the authentication thread */
691 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
692 error("PAM: failed create sockets: %s", strerror(errno));
36e94dc5 693 free(ctxt);
16c343f1
PA
694 return (NULL);
695 }
696 ctxt->pam_psock = socks[0];
697 ctxt->pam_csock = socks[1];
698 if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
699 error("PAM: failed to start authentication thread: %s",
700 strerror(errno));
701 close(socks[0]);
702 close(socks[1]);
36e94dc5 703 free(ctxt);
16c343f1
PA
704 return (NULL);
705 }
706 cleanup_ctxt = ctxt;
707 return (ctxt);
708}
709
710static int
711sshpam_query(void *ctx, char **name, char **info,
712 u_int *num, char ***prompts, u_int **echo_on)
713{
e9778795 714 struct ssh *ssh = active_state; /* XXX */
16c343f1
PA
715 Buffer buffer;
716 struct pam_ctxt *ctxt = ctx;
717 size_t plen;
718 u_char type;
719 char *msg;
720 size_t len, mlen;
721
722 debug3("PAM: %s entering", __func__);
723 buffer_init(&buffer);
724 *name = xstrdup("");
725 *info = xstrdup("");
726 *prompts = xmalloc(sizeof(char *));
727 **prompts = NULL;
728 plen = 0;
729 *echo_on = xmalloc(sizeof(u_int));
730 while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
731 type = buffer_get_char(&buffer);
732 msg = buffer_get_string(&buffer, NULL);
733 mlen = strlen(msg);
734 switch (type) {
735 case PAM_PROMPT_ECHO_ON:
736 case PAM_PROMPT_ECHO_OFF:
737 *num = 1;
738 len = plen + mlen + 1;
e9778795 739 **prompts = xreallocarray(**prompts, 1, len);
16c343f1
PA
740 strlcpy(**prompts + plen, msg, len - plen);
741 plen += mlen;
742 **echo_on = (type == PAM_PROMPT_ECHO_ON);
36e94dc5 743 free(msg);
16c343f1
PA
744 return (0);
745 case PAM_ERROR_MSG:
746 case PAM_TEXT_INFO:
747 /* accumulate messages */
748 len = plen + mlen + 2;
e9778795 749 **prompts = xreallocarray(**prompts, 1, len);
16c343f1
PA
750 strlcpy(**prompts + plen, msg, len - plen);
751 plen += mlen;
752 strlcat(**prompts + plen, "\n", len - plen);
753 plen++;
36e94dc5 754 free(msg);
16c343f1
PA
755 break;
756 case PAM_ACCT_EXPIRED:
e9778795
PA
757 case PAM_MAXTRIES:
758 if (type == PAM_ACCT_EXPIRED)
759 sshpam_account_status = 0;
760 if (type == PAM_MAXTRIES)
761 sshpam_set_maxtries_reached(1);
16c343f1
PA
762 /* FALLTHROUGH */
763 case PAM_AUTH_ERR:
764 debug3("PAM: %s", pam_strerror(sshpam_handle, type));
765 if (**prompts != NULL && strlen(**prompts) != 0) {
766 *info = **prompts;
767 **prompts = NULL;
768 *num = 0;
769 **echo_on = 0;
770 ctxt->pam_done = -1;
36e94dc5 771 free(msg);
16c343f1
PA
772 return 0;
773 }
774 /* FALLTHROUGH */
775 case PAM_SUCCESS:
776 if (**prompts != NULL) {
777 /* drain any accumulated messages */
778 debug("PAM: %s", **prompts);
779 buffer_append(&loginmsg, **prompts,
780 strlen(**prompts));
36e94dc5 781 free(**prompts);
16c343f1
PA
782 **prompts = NULL;
783 }
784 if (type == PAM_SUCCESS) {
785 if (!sshpam_authctxt->valid ||
786 (sshpam_authctxt->pw->pw_uid == 0 &&
787 options.permit_root_login != PERMIT_YES))
788 fatal("Internal error: PAM auth "
789 "succeeded when it should have "
790 "failed");
791 import_environments(&buffer);
792 *num = 0;
793 **echo_on = 0;
794 ctxt->pam_done = 1;
36e94dc5 795 free(msg);
16c343f1
PA
796 return (0);
797 }
798 error("PAM: %s for %s%.100s from %.100s", msg,
799 sshpam_authctxt->valid ? "" : "illegal user ",
800 sshpam_authctxt->user,
e9778795 801 auth_get_canonical_hostname(ssh, options.use_dns));
16c343f1
PA
802 /* FALLTHROUGH */
803 default:
804 *num = 0;
805 **echo_on = 0;
36e94dc5 806 free(msg);
16c343f1
PA
807 ctxt->pam_done = -1;
808 return (-1);
809 }
810 }
811 return (-1);
812}
813
e9778795
PA
814/*
815 * Returns a junk password of identical length to that the user supplied.
816 * Used to mitigate timing attacks against crypt(3)/PAM stacks that
817 * vary processing time in proportion to password length.
818 */
819static char *
820fake_password(const char *wire_password)
821{
822 const char junk[] = "\b\n\r\177INCORRECT";
823 char *ret = NULL;
824 size_t i, l = wire_password != NULL ? strlen(wire_password) : 0;
825
826 if (l >= INT_MAX)
827 fatal("%s: password length too long: %zu", __func__, l);
828
829 ret = malloc(l + 1);
2c9c1408
MD
830 if (ret == NULL)
831 return NULL;
e9778795
PA
832 for (i = 0; i < l; i++)
833 ret[i] = junk[i % (sizeof(junk) - 1)];
834 ret[i] = '\0';
835 return ret;
836}
837
16c343f1
PA
838/* XXX - see also comment in auth-chall.c:verify_response */
839static int
840sshpam_respond(void *ctx, u_int num, char **resp)
841{
842 Buffer buffer;
843 struct pam_ctxt *ctxt = ctx;
e9778795 844 char *fake;
16c343f1
PA
845
846 debug2("PAM: %s entering, %u responses", __func__, num);
847 switch (ctxt->pam_done) {
848 case 1:
849 sshpam_authenticated = 1;
850 return (0);
851 case 0:
852 break;
853 default:
854 return (-1);
855 }
856 if (num != 1) {
857 error("PAM: expected one response, got %u", num);
858 return (-1);
859 }
860 buffer_init(&buffer);
861 if (sshpam_authctxt->valid &&
862 (sshpam_authctxt->pw->pw_uid != 0 ||
863 options.permit_root_login == PERMIT_YES))
864 buffer_put_cstring(&buffer, *resp);
e9778795
PA
865 else {
866 fake = fake_password(*resp);
867 buffer_put_cstring(&buffer, fake);
868 free(fake);
869 }
16c343f1
PA
870 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
871 buffer_free(&buffer);
872 return (-1);
873 }
874 buffer_free(&buffer);
875 return (1);
876}
877
878static void
879sshpam_free_ctx(void *ctxtp)
880{
881 struct pam_ctxt *ctxt = ctxtp;
882
883 debug3("PAM: %s entering", __func__);
884 sshpam_thread_cleanup();
36e94dc5 885 free(ctxt);
16c343f1
PA
886 /*
887 * We don't call sshpam_cleanup() here because we may need the PAM
888 * handle at a later stage, e.g. when setting up a session. It's
889 * still on the cleanup list, so pam_end() *will* be called before
890 * the server process terminates.
891 */
892}
893
894KbdintDevice sshpam_device = {
895 "pam",
896 sshpam_init_ctx,
897 sshpam_query,
898 sshpam_respond,
899 sshpam_free_ctx
900};
901
902KbdintDevice mm_sshpam_device = {
903 "pam",
904 mm_sshpam_init_ctx,
905 mm_sshpam_query,
906 mm_sshpam_respond,
907 mm_sshpam_free_ctx
908};
909
910/*
911 * This replaces auth-pam.c
912 */
913void
914start_pam(Authctxt *authctxt)
915{
916 if (!options.use_pam)
917 fatal("PAM: initialisation requested when UsePAM=no");
918
919 if (sshpam_init(authctxt) == -1)
920 fatal("PAM: initialisation failed");
921}
922
923void
924finish_pam(void)
925{
926 sshpam_cleanup();
927}
928
2c9c1408
MD
929static void
930expose_authinfo(const char *caller)
931{
932 char *auth_info;
933
934 /*
935 * Expose authentication information to PAM.
936 * The enviornment variable is versioned. Please increment the
937 * version suffix if the format of session_info changes.
938 */
939 if (sshpam_authctxt->session_info == NULL)
940 auth_info = xstrdup("");
941 else if ((auth_info = sshbuf_dup_string(
942 sshpam_authctxt->session_info)) == NULL)
943 fatal("%s: sshbuf_dup_string failed", __func__);
944
945 debug2("%s: auth information in SSH_AUTH_INFO_0", caller);
946 do_pam_putenv("SSH_AUTH_INFO_0", auth_info);
947 free(auth_info);
948}
949
16c343f1
PA
950u_int
951do_pam_account(void)
952{
953 debug("%s: called", __func__);
954 if (sshpam_account_status != -1)
955 return (sshpam_account_status);
956
2c9c1408
MD
957 expose_authinfo(__func__);
958
16c343f1
PA
959 sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
960 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
961 pam_strerror(sshpam_handle, sshpam_err));
962
963 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
964 sshpam_account_status = 0;
965 return (sshpam_account_status);
966 }
967
968 if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
969 sshpam_password_change_required(1);
970
971 sshpam_account_status = 1;
972 return (sshpam_account_status);
973}
974
16c343f1
PA
975void
976do_pam_setcred(int init)
977{
978 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
979 (const void *)&store_conv);
980 if (sshpam_err != PAM_SUCCESS)
981 fatal("PAM: failed to set PAM_CONV: %s",
982 pam_strerror(sshpam_handle, sshpam_err));
983 if (init) {
984 debug("PAM: establishing credentials");
985 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
986 } else {
987 debug("PAM: reinitializing credentials");
988 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
989 }
990 if (sshpam_err == PAM_SUCCESS) {
991 sshpam_cred_established = 1;
992 return;
993 }
994 if (sshpam_authenticated)
995 fatal("PAM: pam_setcred(): %s",
996 pam_strerror(sshpam_handle, sshpam_err));
997 else
998 debug("PAM: pam_setcred(): %s",
999 pam_strerror(sshpam_handle, sshpam_err));
1000}
1001
1002static int
1003sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
1004 struct pam_response **resp, void *data)
1005{
1006 char input[PAM_MAX_MSG_SIZE];
1007 struct pam_response *reply;
1008 int i;
1009
1010 debug3("PAM: %s called with %d messages", __func__, n);
1011
1012 *resp = NULL;
1013
1014 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
1015 return (PAM_CONV_ERR);
1016
1017 if ((reply = calloc(n, sizeof(*reply))) == NULL)
1018 return (PAM_CONV_ERR);
1019
1020 for (i = 0; i < n; ++i) {
1021 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1022 case PAM_PROMPT_ECHO_OFF:
1023 reply[i].resp =
1024 read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
1025 RP_ALLOW_STDIN);
1026 reply[i].resp_retcode = PAM_SUCCESS;
1027 break;
1028 case PAM_PROMPT_ECHO_ON:
1029 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1030 if (fgets(input, sizeof input, stdin) == NULL)
1031 input[0] = '\0';
1032 if ((reply[i].resp = strdup(input)) == NULL)
1033 goto fail;
1034 reply[i].resp_retcode = PAM_SUCCESS;
1035 break;
1036 case PAM_ERROR_MSG:
1037 case PAM_TEXT_INFO:
1038 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1039 reply[i].resp_retcode = PAM_SUCCESS;
1040 break;
1041 default:
1042 goto fail;
1043 }
1044 }
1045 *resp = reply;
1046 return (PAM_SUCCESS);
1047
1048 fail:
1049 for(i = 0; i < n; i++) {
36e94dc5 1050 free(reply[i].resp);
16c343f1 1051 }
36e94dc5 1052 free(reply);
16c343f1
PA
1053 return (PAM_CONV_ERR);
1054}
1055
1056static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
1057
1058/*
1059 * XXX this should be done in the authentication phase, but ssh1 doesn't
1060 * support that
1061 */
1062void
1063do_pam_chauthtok(void)
1064{
1065 if (use_privsep)
1066 fatal("Password expired (unable to change with privsep)");
1067 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1068 (const void *)&tty_conv);
1069 if (sshpam_err != PAM_SUCCESS)
1070 fatal("PAM: failed to set PAM_CONV: %s",
1071 pam_strerror(sshpam_handle, sshpam_err));
1072 debug("PAM: changing password");
1073 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
1074 if (sshpam_err != PAM_SUCCESS)
1075 fatal("PAM: pam_chauthtok(): %s",
1076 pam_strerror(sshpam_handle, sshpam_err));
1077}
1078
1079void
1080do_pam_session(void)
1081{
1082 debug3("PAM: opening session");
2c9c1408
MD
1083
1084 expose_authinfo(__func__);
1085
16c343f1
PA
1086 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1087 (const void *)&store_conv);
1088 if (sshpam_err != PAM_SUCCESS)
1089 fatal("PAM: failed to set PAM_CONV: %s",
1090 pam_strerror(sshpam_handle, sshpam_err));
1091 sshpam_err = pam_open_session(sshpam_handle, 0);
1092 if (sshpam_err == PAM_SUCCESS)
1093 sshpam_session_open = 1;
1094 else {
1095 sshpam_session_open = 0;
1096 disable_forwarding();
1097 error("PAM: pam_open_session(): %s",
1098 pam_strerror(sshpam_handle, sshpam_err));
1099 }
1100
1101}
1102
1103int
1104is_pam_session_open(void)
1105{
1106 return sshpam_session_open;
1107}
1108
1109/*
1110 * Set a PAM environment string. We need to do this so that the session
1111 * modules can handle things like Kerberos/GSI credentials that appear
1112 * during the ssh authentication process.
1113 */
1114int
1115do_pam_putenv(char *name, char *value)
1116{
1117 int ret = 1;
1118#ifdef HAVE_PAM_PUTENV
1119 char *compound;
1120 size_t len;
1121
1122 len = strlen(name) + strlen(value) + 2;
1123 compound = xmalloc(len);
1124
1125 snprintf(compound, len, "%s=%s", name, value);
1126 ret = pam_putenv(sshpam_handle, compound);
36e94dc5 1127 free(compound);
16c343f1
PA
1128#endif
1129
1130 return (ret);
1131}
1132
1133char **
1134fetch_pam_child_environment(void)
1135{
1136 return sshpam_env;
1137}
1138
1139char **
1140fetch_pam_environment(void)
1141{
1142 return (pam_getenvlist(sshpam_handle));
1143}
1144
1145void
1146free_pam_environment(char **env)
1147{
1148 char **envp;
1149
1150 if (env == NULL)
1151 return;
1152
1153 for (envp = env; *envp; envp++)
36e94dc5
PA
1154 free(*envp);
1155 free(env);
16c343f1
PA
1156}
1157
1158/*
1159 * "Blind" conversation function for password authentication. Assumes that
1160 * echo-off prompts are for the password and stores messages for later
1161 * display.
1162 */
1163static int
1164sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1165 struct pam_response **resp, void *data)
1166{
1167 struct pam_response *reply;
1168 int i;
1169 size_t len;
1170
1171 debug3("PAM: %s called with %d messages", __func__, n);
1172
1173 *resp = NULL;
1174
1175 if (n <= 0 || n > PAM_MAX_NUM_MSG)
1176 return (PAM_CONV_ERR);
1177
1178 if ((reply = calloc(n, sizeof(*reply))) == NULL)
1179 return (PAM_CONV_ERR);
1180
1181 for (i = 0; i < n; ++i) {
1182 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1183 case PAM_PROMPT_ECHO_OFF:
1184 if (sshpam_password == NULL)
1185 goto fail;
1186 if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1187 goto fail;
1188 reply[i].resp_retcode = PAM_SUCCESS;
1189 break;
1190 case PAM_ERROR_MSG:
1191 case PAM_TEXT_INFO:
1192 len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1193 if (len > 0) {
1194 buffer_append(&loginmsg,
1195 PAM_MSG_MEMBER(msg, i, msg), len);
1196 buffer_append(&loginmsg, "\n", 1);
1197 }
1198 if ((reply[i].resp = strdup("")) == NULL)
1199 goto fail;
1200 reply[i].resp_retcode = PAM_SUCCESS;
1201 break;
1202 default:
1203 goto fail;
1204 }
1205 }
1206 *resp = reply;
1207 return (PAM_SUCCESS);
1208
1209 fail:
1210 for(i = 0; i < n; i++) {
36e94dc5 1211 free(reply[i].resp);
16c343f1 1212 }
36e94dc5 1213 free(reply);
16c343f1
PA
1214 return (PAM_CONV_ERR);
1215}
1216
1217static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1218
1219/*
1220 * Attempt password authentication via PAM
1221 */
1222int
1223sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1224{
1225 int flags = (options.permit_empty_passwd == 0 ?
1226 PAM_DISALLOW_NULL_AUTHTOK : 0);
e9778795 1227 char *fake = NULL;
16c343f1
PA
1228
1229 if (!options.use_pam || sshpam_handle == NULL)
1230 fatal("PAM: %s called when PAM disabled or failed to "
1231 "initialise.", __func__);
1232
1233 sshpam_password = password;
1234 sshpam_authctxt = authctxt;
1235
1236 /*
1237 * If the user logging in is invalid, or is root but is not permitted
1238 * by PermitRootLogin, use an invalid password to prevent leaking
1239 * information via timing (eg if the PAM config has a delay on fail).
1240 */
1241 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1242 options.permit_root_login != PERMIT_YES))
e9778795 1243 sshpam_password = fake = fake_password(password);
16c343f1
PA
1244
1245 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1246 (const void *)&passwd_conv);
1247 if (sshpam_err != PAM_SUCCESS)
1248 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1249 pam_strerror(sshpam_handle, sshpam_err));
1250
1251 sshpam_err = pam_authenticate(sshpam_handle, flags);
1252 sshpam_password = NULL;
e9778795
PA
1253 free(fake);
1254 if (sshpam_err == PAM_MAXTRIES)
1255 sshpam_set_maxtries_reached(1);
16c343f1
PA
1256 if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1257 debug("PAM: password authentication accepted for %.100s",
1258 authctxt->user);
1259 return 1;
1260 } else {
1261 debug("PAM: password authentication failed for %.100s: %s",
1262 authctxt->valid ? authctxt->user : "an illegal user",
1263 pam_strerror(sshpam_handle, sshpam_err));
1264 return 0;
1265 }
1266}
e9778795
PA
1267
1268int
1269sshpam_get_maxtries_reached(void)
1270{
1271 return sshpam_maxtries_reached;
1272}
1273
1274void
1275sshpam_set_maxtries_reached(int reached)
1276{
1277 if (reached == 0 || sshpam_maxtries_reached)
1278 return;
1279 sshpam_maxtries_reached = 1;
1280 options.password_authentication = 0;
1281 options.kbd_interactive_authentication = 0;
1282 options.challenge_response_authentication = 0;
1283}
16c343f1 1284#endif /* USE_PAM */