bde0a8f561f24a27bfb3201ed34257d2a57bc706
[dragonfly.git] / crypto / openssh / auth-pam.c
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
48 /* Based on FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des */
49
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
69 #if !defined(SSHD_PAM_SERVICE)
70 extern char *__progname;
71 # define SSHD_PAM_SERVICE               __progname
72 #endif
73
74 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */
75 #ifdef PAM_SUN_CODEBASE
76 # define sshpam_const           /* Solaris, HP-UX, SunOS */
77 #else
78 # define sshpam_const   const   /* LinuxPAM, OpenPAM, AIX */
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 "sshbuf.h"
90 #include "ssherr.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
107 extern ServerOptions options;
108 extern struct sshbuf *loginmsg;
109 extern 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  */
128 typedef pthread_t sp_pthread_t;
129 #else
130 typedef pid_t sp_pthread_t;
131 #define pthread_exit    fake_pthread_exit
132 #define pthread_create  fake_pthread_create
133 #define pthread_cancel  fake_pthread_cancel
134 #define pthread_join    fake_pthread_join
135 #endif
136
137 struct pam_ctxt {
138         sp_pthread_t     pam_thread;
139         int              pam_psock;
140         int              pam_csock;
141         int              pam_done;
142 };
143
144 static void sshpam_free_ctx(void *);
145 static struct pam_ctxt *cleanup_ctxt;
146
147 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
148 /*
149  * Simulate threads with processes.
150  */
151
152 static int sshpam_thread_status = -1;
153 static mysig_t sshpam_oldsig;
154
155 static void
156 sshpam_sigchld_handler(int sig)
157 {
158         signal(SIGCHLD, SIG_DFL);
159         if (cleanup_ctxt == NULL)
160                 return; /* handler called after PAM cleanup, shouldn't happen */
161         if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
162             <= 0) {
163                 /* PAM thread has not exitted, privsep slave must have */
164                 kill(cleanup_ctxt->pam_thread, SIGTERM);
165                 while (waitpid(cleanup_ctxt->pam_thread,
166                     &sshpam_thread_status, 0) == -1) {
167                         if (errno == EINTR)
168                                 continue;
169                         return;
170                 }
171         }
172         if (WIFSIGNALED(sshpam_thread_status) &&
173             WTERMSIG(sshpam_thread_status) == SIGTERM)
174                 return; /* terminated by pthread_cancel */
175         if (!WIFEXITED(sshpam_thread_status))
176                 sigdie("PAM: authentication thread exited unexpectedly");
177         if (WEXITSTATUS(sshpam_thread_status) != 0)
178                 sigdie("PAM: authentication thread exited uncleanly");
179 }
180
181 /* ARGSUSED */
182 static void
183 pthread_exit(void *value)
184 {
185         _exit(0);
186 }
187
188 /* ARGSUSED */
189 static int
190 pthread_create(sp_pthread_t *thread, const void *attr,
191     void *(*thread_start)(void *), void *arg)
192 {
193         pid_t pid;
194         struct pam_ctxt *ctx = arg;
195
196         sshpam_thread_status = -1;
197         switch ((pid = fork())) {
198         case -1:
199                 error("fork(): %s", strerror(errno));
200                 return (-1);
201         case 0:
202                 close(ctx->pam_psock);
203                 ctx->pam_psock = -1;
204                 thread_start(arg);
205                 _exit(1);
206         default:
207                 *thread = pid;
208                 close(ctx->pam_csock);
209                 ctx->pam_csock = -1;
210                 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
211                 return (0);
212         }
213 }
214
215 static int
216 pthread_cancel(sp_pthread_t thread)
217 {
218         signal(SIGCHLD, sshpam_oldsig);
219         return (kill(thread, SIGTERM));
220 }
221
222 /* ARGSUSED */
223 static int
224 pthread_join(sp_pthread_t thread, void **value)
225 {
226         int status;
227
228         if (sshpam_thread_status != -1)
229                 return (sshpam_thread_status);
230         signal(SIGCHLD, sshpam_oldsig);
231         while (waitpid(thread, &status, 0) == -1) {
232                 if (errno == EINTR)
233                         continue;
234                 fatal("%s: waitpid: %s", __func__, strerror(errno));
235         }
236         return (status);
237 }
238 #endif
239
240
241 static pam_handle_t *sshpam_handle = NULL;
242 static int sshpam_err = 0;
243 static int sshpam_authenticated = 0;
244 static int sshpam_session_open = 0;
245 static int sshpam_cred_established = 0;
246 static int sshpam_account_status = -1;
247 static int sshpam_maxtries_reached = 0;
248 static char **sshpam_env = NULL;
249 static Authctxt *sshpam_authctxt = NULL;
250 static const char *sshpam_password = NULL;
251 static char *sshpam_rhost = NULL;
252 static char *sshpam_laddr = NULL;
253 static char *sshpam_conninfo = NULL;
254
255 /* Some PAM implementations don't implement this */
256 #ifndef HAVE_PAM_GETENVLIST
257 static char **
258 pam_getenvlist(pam_handle_t *pamh)
259 {
260         /*
261          * XXX - If necessary, we can still support envrionment passing
262          * for platforms without pam_getenvlist by searching for known
263          * env vars (e.g. KRB5CCNAME) from the PAM environment.
264          */
265          return NULL;
266 }
267 #endif
268
269 /*
270  * Some platforms, notably Solaris, do not enforce password complexity
271  * rules during pam_chauthtok() if the real uid of the calling process
272  * is 0, on the assumption that it's being called by "passwd" run by root.
273  * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
274  * the right thing.
275  */
276 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
277 static int
278 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
279 {
280         int result;
281
282         if (sshpam_authctxt == NULL)
283                 fatal("PAM: sshpam_authctxt not initialized");
284         if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
285                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
286         result = pam_chauthtok(pamh, flags);
287         if (setreuid(0, -1) == -1)
288                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
289         return result;
290 }
291 # define pam_chauthtok(a,b)     (sshpam_chauthtok_ruid((a), (b)))
292 #endif
293
294 void
295 sshpam_password_change_required(int reqd)
296 {
297         extern struct sshauthopt *auth_opts;
298         static int saved_port, saved_agent, saved_x11;
299
300         debug3("%s %d", __func__, reqd);
301         if (sshpam_authctxt == NULL)
302                 fatal("%s: PAM authctxt not initialized", __func__);
303         sshpam_authctxt->force_pwchange = reqd;
304         if (reqd) {
305                 saved_port = auth_opts->permit_port_forwarding_flag;
306                 saved_agent = auth_opts->permit_agent_forwarding_flag;
307                 saved_x11 = auth_opts->permit_x11_forwarding_flag;
308                 auth_opts->permit_port_forwarding_flag = 0;
309                 auth_opts->permit_agent_forwarding_flag = 0;
310                 auth_opts->permit_x11_forwarding_flag = 0;
311         } else {
312                 if (saved_port)
313                         auth_opts->permit_port_forwarding_flag = saved_port;
314                 if (saved_agent)
315                         auth_opts->permit_agent_forwarding_flag = saved_agent;
316                 if (saved_x11)
317                         auth_opts->permit_x11_forwarding_flag = saved_x11;
318         }
319 }
320
321 /* Import regular and PAM environment from subprocess */
322 static void
323 import_environments(struct sshbuf *b)
324 {
325         char *env;
326         u_int n, i, num_env;
327         int r;
328
329         debug3("PAM: %s entering", __func__);
330
331 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
332         /* Import variables set by do_pam_account */
333         if ((r = sshbuf_get_u32(b, &n)) != 0)
334                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
335         if (n > INT_MAX)
336                 fatal("%s: invalid PAM account status %u", __func__, n);
337         sshpam_account_status = (int)n;
338         if ((r = sshbuf_get_u32(b, &n)) != 0)
339                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
340         sshpam_password_change_required(n != 0);
341
342         /* Import environment from subprocess */
343         if ((r = sshbuf_get_u32(b, &num_env)) != 0)
344                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
345         if (num_env > 1024)
346                 fatal("%s: received %u environment variables, expected <= 1024",
347                     __func__, num_env);
348         sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env));
349         debug3("PAM: num env strings %d", num_env);
350         for(i = 0; i < num_env; i++) {
351                 if ((r = sshbuf_get_cstring(b, &(sshpam_env[i]), NULL)) != 0)
352                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
353         }
354         sshpam_env[num_env] = NULL;
355
356         /* Import PAM environment from subprocess */
357         if ((r = sshbuf_get_u32(b, &num_env)) != 0)
358                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
359         debug("PAM: num PAM env strings %d", num_env);
360         for (i = 0; i < num_env; i++) {
361                 if ((r = sshbuf_get_cstring(b, &env, NULL)) != 0)
362                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
363 #ifdef HAVE_PAM_PUTENV
364                 /* Errors are not fatal here */
365                 if ((r = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
366                         error("PAM: pam_putenv: %s",
367                             pam_strerror(sshpam_handle, r));
368                 }
369 #endif
370                 /* XXX leak env? */
371         }
372 #endif
373 }
374
375 /*
376  * Conversation function for authentication thread.
377  */
378 static int
379 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
380     struct pam_response **resp, void *data)
381 {
382         struct sshbuf *buffer;
383         struct pam_ctxt *ctxt;
384         struct pam_response *reply;
385         int r, i;
386         u_char status;
387
388         debug3("PAM: %s entering, %d messages", __func__, n);
389         *resp = NULL;
390
391         if (data == NULL) {
392                 error("PAM: conversation function passed a null context");
393                 return (PAM_CONV_ERR);
394         }
395         ctxt = data;
396         if (n <= 0 || n > PAM_MAX_NUM_MSG)
397                 return (PAM_CONV_ERR);
398
399         if ((reply = calloc(n, sizeof(*reply))) == NULL)
400                 return PAM_CONV_ERR;
401         if ((buffer = sshbuf_new()) == NULL) {
402                 free(reply);
403                 return PAM_CONV_ERR;
404         }
405
406         for (i = 0; i < n; ++i) {
407                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
408                 case PAM_PROMPT_ECHO_OFF:
409                 case PAM_PROMPT_ECHO_ON:
410                         if ((r = sshbuf_put_cstring(buffer,
411                             PAM_MSG_MEMBER(msg, i, msg))) != 0)
412                                 fatal("%s: buffer error: %s",
413                                     __func__, ssh_err(r));
414                         if (ssh_msg_send(ctxt->pam_csock,
415                             PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1)
416                                 goto fail;
417
418                         if (ssh_msg_recv(ctxt->pam_csock, buffer) == -1)
419                                 goto fail;
420                         if ((r = sshbuf_get_u8(buffer, &status)) != 0)
421                                 fatal("%s: buffer error: %s",
422                                     __func__, ssh_err(r));
423                         if (status != PAM_AUTHTOK)
424                                 goto fail;
425                         if ((r = sshbuf_get_cstring(buffer,
426                             &reply[i].resp, NULL)) != 0)
427                                 fatal("%s: buffer error: %s",
428                                     __func__, ssh_err(r));
429                         break;
430                 case PAM_ERROR_MSG:
431                 case PAM_TEXT_INFO:
432                         if ((r = sshbuf_put_cstring(buffer,
433                             PAM_MSG_MEMBER(msg, i, msg))) != 0)
434                                 fatal("%s: buffer error: %s",
435                                     __func__, ssh_err(r));
436                         if (ssh_msg_send(ctxt->pam_csock,
437                             PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1)
438                                 goto fail;
439                         break;
440                 default:
441                         goto fail;
442                 }
443                 sshbuf_reset(buffer);
444         }
445         sshbuf_free(buffer);
446         *resp = reply;
447         return (PAM_SUCCESS);
448
449  fail:
450         for(i = 0; i < n; i++) {
451                 free(reply[i].resp);
452         }
453         free(reply);
454         sshbuf_free(buffer);
455         return (PAM_CONV_ERR);
456 }
457
458 /*
459  * Authentication thread.
460  */
461 static void *
462 sshpam_thread(void *ctxtp)
463 {
464         struct pam_ctxt *ctxt = ctxtp;
465         struct sshbuf *buffer = NULL;
466         struct pam_conv sshpam_conv;
467         int r, flags = (options.permit_empty_passwd == 0 ?
468             PAM_DISALLOW_NULL_AUTHTOK : 0);
469 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
470         extern char **environ;
471         char **env_from_pam;
472         u_int i;
473         const char *pam_user;
474         const char **ptr_pam_user = &pam_user;
475         char *tz = getenv("TZ");
476
477         sshpam_err = pam_get_item(sshpam_handle, PAM_USER,
478             (sshpam_const void **)ptr_pam_user);
479         if (sshpam_err != PAM_SUCCESS)
480                 goto auth_fail;
481
482         environ[0] = NULL;
483         if (tz != NULL)
484                 if (setenv("TZ", tz, 1) == -1)
485                         error("PAM: could not set TZ environment: %s",
486                             strerror(errno));
487
488         if (sshpam_authctxt != NULL) {
489                 setproctitle("%s [pam]",
490                     sshpam_authctxt->valid ? pam_user : "unknown");
491         }
492 #endif
493
494         sshpam_conv.conv = sshpam_thread_conv;
495         sshpam_conv.appdata_ptr = ctxt;
496
497         if (sshpam_authctxt == NULL)
498                 fatal("%s: PAM authctxt not initialized", __func__);
499
500         if ((buffer = sshbuf_new()) == NULL)
501                 fatal("%s: sshbuf_new failed", __func__);
502
503         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
504             (const void *)&sshpam_conv);
505         if (sshpam_err != PAM_SUCCESS)
506                 goto auth_fail;
507         sshpam_err = pam_authenticate(sshpam_handle, flags);
508         if (sshpam_err == PAM_MAXTRIES)
509                 sshpam_set_maxtries_reached(1);
510         if (sshpam_err != PAM_SUCCESS)
511                 goto auth_fail;
512
513         if (!do_pam_account()) {
514                 sshpam_err = PAM_ACCT_EXPIRED;
515                 goto auth_fail;
516         }
517         if (sshpam_authctxt->force_pwchange) {
518                 sshpam_err = pam_chauthtok(sshpam_handle,
519                     PAM_CHANGE_EXPIRED_AUTHTOK);
520                 if (sshpam_err != PAM_SUCCESS)
521                         goto auth_fail;
522                 sshpam_password_change_required(0);
523         }
524
525         if ((r = sshbuf_put_cstring(buffer, "OK")) != 0)
526                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
527
528 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
529         /* Export variables set by do_pam_account */
530         if ((r = sshbuf_put_u32(buffer, sshpam_account_status)) != 0 ||
531             (r = sshbuf_put_u32(buffer, sshpam_authctxt->force_pwchange)) != 0)
532                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
533
534         /* Export any environment strings set in child */
535         for (i = 0; environ[i] != NULL; i++) {
536                 /* Count */
537                 if (i > INT_MAX)
538                         fatal("%s: too many enviornment strings", __func__);
539         }
540         if ((r = sshbuf_put_u32(buffer, i)) != 0)
541                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
542         for (i = 0; environ[i] != NULL; i++) {
543                 if ((r = sshbuf_put_cstring(buffer, environ[i])) != 0)
544                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
545         }
546         /* Export any environment strings set by PAM in child */
547         env_from_pam = pam_getenvlist(sshpam_handle);
548         for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) {
549                 /* Count */
550                 if (i > INT_MAX)
551                         fatal("%s: too many PAM enviornment strings", __func__);
552         }
553         if ((r = sshbuf_put_u32(buffer, i)) != 0)
554                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
555         for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) {
556                 if ((r = sshbuf_put_cstring(buffer, env_from_pam[i])) != 0)
557                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
558         }
559 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */
560
561         /* XXX - can't do much about an error here */
562         ssh_msg_send(ctxt->pam_csock, sshpam_err, buffer);
563         sshbuf_free(buffer);
564         pthread_exit(NULL);
565
566  auth_fail:
567         if ((r = sshbuf_put_cstring(buffer,
568             pam_strerror(sshpam_handle, sshpam_err))) != 0)
569                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
570         /* XXX - can't do much about an error here */
571         if (sshpam_err == PAM_ACCT_EXPIRED)
572                 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, buffer);
573         else if (sshpam_maxtries_reached)
574                 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, buffer);
575         else
576                 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, buffer);
577         sshbuf_free(buffer);
578         pthread_exit(NULL);
579
580         return (NULL); /* Avoid warning for non-pthread case */
581 }
582
583 void
584 sshpam_thread_cleanup(void)
585 {
586         struct pam_ctxt *ctxt = cleanup_ctxt;
587
588         debug3("PAM: %s entering", __func__);
589         if (ctxt != NULL && ctxt->pam_thread != 0) {
590                 pthread_cancel(ctxt->pam_thread);
591                 pthread_join(ctxt->pam_thread, NULL);
592                 close(ctxt->pam_psock);
593                 close(ctxt->pam_csock);
594                 memset(ctxt, 0, sizeof(*ctxt));
595                 cleanup_ctxt = NULL;
596         }
597 }
598
599 static int
600 sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
601     struct pam_response **resp, void *data)
602 {
603         debug3("PAM: %s entering, %d messages", __func__, n);
604         return (PAM_CONV_ERR);
605 }
606
607 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
608
609 static int
610 sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
611     struct pam_response **resp, void *data)
612 {
613         struct pam_response *reply;
614         int r, i;
615
616         debug3("PAM: %s called with %d messages", __func__, n);
617         *resp = NULL;
618
619         if (n <= 0 || n > PAM_MAX_NUM_MSG)
620                 return (PAM_CONV_ERR);
621
622         if ((reply = calloc(n, sizeof(*reply))) == NULL)
623                 return (PAM_CONV_ERR);
624
625         for (i = 0; i < n; ++i) {
626                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
627                 case PAM_ERROR_MSG:
628                 case PAM_TEXT_INFO:
629                         if ((r = sshbuf_putf(loginmsg, "%s\n",
630                             PAM_MSG_MEMBER(msg, i, msg))) != 0)
631                                 fatal("%s: buffer error: %s",
632                                     __func__, ssh_err(r));
633                         reply[i].resp_retcode = PAM_SUCCESS;
634                         break;
635                 default:
636                         goto fail;
637                 }
638         }
639         *resp = reply;
640         return (PAM_SUCCESS);
641
642  fail:
643         for(i = 0; i < n; i++) {
644                 free(reply[i].resp);
645         }
646         free(reply);
647         return (PAM_CONV_ERR);
648 }
649
650 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
651
652 void
653 sshpam_cleanup(void)
654 {
655         if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor()))
656                 return;
657         debug("PAM: cleanup");
658         pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
659         if (sshpam_session_open) {
660                 debug("PAM: closing session");
661                 pam_close_session(sshpam_handle, PAM_SILENT);
662                 sshpam_session_open = 0;
663         }
664         if (sshpam_cred_established) {
665                 debug("PAM: deleting credentials");
666                 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
667                 sshpam_cred_established = 0;
668         }
669         sshpam_authenticated = 0;
670         pam_end(sshpam_handle, sshpam_err);
671         sshpam_handle = NULL;
672 }
673
674 static int
675 sshpam_init(struct ssh *ssh, Authctxt *authctxt)
676 {
677         const char *pam_user, *user = authctxt->user;
678         const char **ptr_pam_user = &pam_user;
679
680         if (sshpam_handle == NULL) {
681                 if (ssh == NULL) {
682                         fatal("%s: called initially with no "
683                             "packet context", __func__);
684                 }
685         } if (sshpam_handle != NULL) {
686                 /* We already have a PAM context; check if the user matches */
687                 sshpam_err = pam_get_item(sshpam_handle,
688                     PAM_USER, (sshpam_const void **)ptr_pam_user);
689                 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
690                         return (0);
691                 pam_end(sshpam_handle, sshpam_err);
692                 sshpam_handle = NULL;
693         }
694         debug("PAM: initializing for \"%s\"", user);
695         sshpam_err =
696             pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
697         sshpam_authctxt = authctxt;
698
699         if (sshpam_err != PAM_SUCCESS) {
700                 pam_end(sshpam_handle, sshpam_err);
701                 sshpam_handle = NULL;
702                 return (-1);
703         }
704
705         if (ssh != NULL && sshpam_rhost == NULL) {
706                 /*
707                  * We need to cache these as we don't have packet context
708                  * during the kbdint flow.
709                  */
710                 sshpam_rhost = xstrdup(auth_get_canonical_hostname(ssh,
711                     options.use_dns));
712                 sshpam_laddr = get_local_ipaddr(
713                     ssh_packet_get_connection_in(ssh));
714                 xasprintf(&sshpam_conninfo, "SSH_CONNECTION=%.50s %d %.50s %d",
715                     ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
716                     sshpam_laddr, ssh_local_port(ssh));
717         }
718         if (sshpam_rhost != NULL) {
719                 debug("PAM: setting PAM_RHOST to \"%s\"", sshpam_rhost);
720                 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST,
721                     sshpam_rhost);
722                 if (sshpam_err != PAM_SUCCESS) {
723                         pam_end(sshpam_handle, sshpam_err);
724                         sshpam_handle = NULL;
725                         return (-1);
726                 }
727                 /* Put SSH_CONNECTION in the PAM environment too */
728                 pam_putenv(sshpam_handle, sshpam_conninfo);
729         }
730
731 #ifdef PAM_TTY_KLUDGE
732         /*
733          * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
734          * sshd doesn't set the tty until too late in the auth process and
735          * may not even set one (for tty-less connections)
736          */
737         debug("PAM: setting PAM_TTY to \"ssh\"");
738         sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
739         if (sshpam_err != PAM_SUCCESS) {
740                 pam_end(sshpam_handle, sshpam_err);
741                 sshpam_handle = NULL;
742                 return (-1);
743         }
744 #endif
745         return (0);
746 }
747
748 static void
749 expose_authinfo(const char *caller)
750 {
751         char *auth_info;
752
753         /*
754          * Expose authentication information to PAM.
755          * The environment variable is versioned. Please increment the
756          * version suffix if the format of session_info changes.
757          */
758         if (sshpam_authctxt->session_info == NULL)
759                 auth_info = xstrdup("");
760         else if ((auth_info = sshbuf_dup_string(
761             sshpam_authctxt->session_info)) == NULL)
762                 fatal("%s: sshbuf_dup_string failed", __func__);
763
764         debug2("%s: auth information in SSH_AUTH_INFO_0", caller);
765         do_pam_putenv("SSH_AUTH_INFO_0", auth_info);
766         free(auth_info);
767 }
768
769 static void *
770 sshpam_init_ctx(Authctxt *authctxt)
771 {
772         struct pam_ctxt *ctxt;
773         int socks[2];
774
775         debug3("PAM: %s entering", __func__);
776         /*
777          * Refuse to start if we don't have PAM enabled or do_pam_account
778          * has previously failed.
779          */
780         if (!options.use_pam || sshpam_account_status == 0)
781                 return NULL;
782
783         /* Initialize PAM */
784         if (sshpam_init(NULL, authctxt) == -1) {
785                 error("PAM: initialization failed");
786                 return (NULL);
787         }
788
789         expose_authinfo(__func__);
790         ctxt = xcalloc(1, sizeof *ctxt);
791
792         /* Start the authentication thread */
793         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
794                 error("PAM: failed create sockets: %s", strerror(errno));
795                 free(ctxt);
796                 return (NULL);
797         }
798         ctxt->pam_psock = socks[0];
799         ctxt->pam_csock = socks[1];
800         if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
801                 error("PAM: failed to start authentication thread: %s",
802                     strerror(errno));
803                 close(socks[0]);
804                 close(socks[1]);
805                 free(ctxt);
806                 return (NULL);
807         }
808         cleanup_ctxt = ctxt;
809         return (ctxt);
810 }
811
812 static int
813 sshpam_query(void *ctx, char **name, char **info,
814     u_int *num, char ***prompts, u_int **echo_on)
815 {
816         struct sshbuf *buffer;
817         struct pam_ctxt *ctxt = ctx;
818         size_t plen;
819         u_char type;
820         char *msg;
821         size_t len, mlen;
822         int r;
823
824         debug3("PAM: %s entering", __func__);
825         if ((buffer = sshbuf_new()) == NULL)
826                 fatal("%s: sshbuf_new failed", __func__);
827         *name = xstrdup("");
828         *info = xstrdup("");
829         *prompts = xmalloc(sizeof(char *));
830         **prompts = NULL;
831         plen = 0;
832         *echo_on = xmalloc(sizeof(u_int));
833         while (ssh_msg_recv(ctxt->pam_psock, buffer) == 0) {
834                 if ((r = sshbuf_get_u8(buffer, &type)) != 0 ||
835                     (r = sshbuf_get_cstring(buffer, &msg, &mlen)) != 0)
836                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
837                 switch (type) {
838                 case PAM_PROMPT_ECHO_ON:
839                 case PAM_PROMPT_ECHO_OFF:
840                         *num = 1;
841                         len = plen + mlen + 1;
842                         **prompts = xreallocarray(**prompts, 1, len);
843                         strlcpy(**prompts + plen, msg, len - plen);
844                         plen += mlen;
845                         **echo_on = (type == PAM_PROMPT_ECHO_ON);
846                         free(msg);
847                         return (0);
848                 case PAM_ERROR_MSG:
849                 case PAM_TEXT_INFO:
850                         /* accumulate messages */
851                         len = plen + mlen + 2;
852                         **prompts = xreallocarray(**prompts, 1, len);
853                         strlcpy(**prompts + plen, msg, len - plen);
854                         plen += mlen;
855                         strlcat(**prompts + plen, "\n", len - plen);
856                         plen++;
857                         free(msg);
858                         break;
859                 case PAM_ACCT_EXPIRED:
860                 case PAM_MAXTRIES:
861                         if (type == PAM_ACCT_EXPIRED)
862                                 sshpam_account_status = 0;
863                         if (type == PAM_MAXTRIES)
864                                 sshpam_set_maxtries_reached(1);
865                         /* FALLTHROUGH */
866                 case PAM_AUTH_ERR:
867                         debug3("PAM: %s", pam_strerror(sshpam_handle, type));
868                         if (**prompts != NULL && strlen(**prompts) != 0) {
869                                 *info = **prompts;
870                                 **prompts = NULL;
871                                 *num = 0;
872                                 **echo_on = 0;
873                                 ctxt->pam_done = -1;
874                                 free(msg);
875                                 return 0;
876                         }
877                         /* FALLTHROUGH */
878                 case PAM_SUCCESS:
879                         if (**prompts != NULL) {
880                                 /* drain any accumulated messages */
881                                 debug("PAM: %s", **prompts);
882                                 if ((r = sshbuf_put(loginmsg, **prompts,
883                                     strlen(**prompts))) != 0)
884                                         fatal("%s: buffer error: %s",
885                                             __func__, ssh_err(r));
886                                 free(**prompts);
887                                 **prompts = NULL;
888                         }
889                         if (type == PAM_SUCCESS) {
890                                 if (!sshpam_authctxt->valid ||
891                                     (sshpam_authctxt->pw->pw_uid == 0 &&
892                                     options.permit_root_login != PERMIT_YES))
893                                         fatal("Internal error: PAM auth "
894                                             "succeeded when it should have "
895                                             "failed");
896                                 import_environments(buffer);
897                                 *num = 0;
898                                 **echo_on = 0;
899                                 ctxt->pam_done = 1;
900                                 free(msg);
901                                 return (0);
902                         }
903                         error("PAM: %s for %s%.100s from %.100s", msg,
904                             sshpam_authctxt->valid ? "" : "illegal user ",
905                             sshpam_authctxt->user, sshpam_rhost);
906                         /* FALLTHROUGH */
907                 default:
908                         *num = 0;
909                         **echo_on = 0;
910                         free(msg);
911                         ctxt->pam_done = -1;
912                         return (-1);
913                 }
914         }
915         return (-1);
916 }
917
918 /*
919  * Returns a junk password of identical length to that the user supplied.
920  * Used to mitigate timing attacks against crypt(3)/PAM stacks that
921  * vary processing time in proportion to password length.
922  */
923 static char *
924 fake_password(const char *wire_password)
925 {
926         const char junk[] = "\b\n\r\177INCORRECT";
927         char *ret = NULL;
928         size_t i, l = wire_password != NULL ? strlen(wire_password) : 0;
929
930         if (l >= INT_MAX)
931                 fatal("%s: password length too long: %zu", __func__, l);
932
933         ret = malloc(l + 1);
934         if (ret == NULL)
935                 return NULL;
936         for (i = 0; i < l; i++)
937                 ret[i] = junk[i % (sizeof(junk) - 1)];
938         ret[i] = '\0';
939         return ret;
940 }
941
942 /* XXX - see also comment in auth-chall.c:verify_response */
943 static int
944 sshpam_respond(void *ctx, u_int num, char **resp)
945 {
946         struct sshbuf *buffer;
947         struct pam_ctxt *ctxt = ctx;
948         char *fake;
949         int r;
950
951         debug2("PAM: %s entering, %u responses", __func__, num);
952         switch (ctxt->pam_done) {
953         case 1:
954                 sshpam_authenticated = 1;
955                 return (0);
956         case 0:
957                 break;
958         default:
959                 return (-1);
960         }
961         if (num != 1) {
962                 error("PAM: expected one response, got %u", num);
963                 return (-1);
964         }
965         if ((buffer = sshbuf_new()) == NULL)
966                 fatal("%s: sshbuf_new failed", __func__);
967         if (sshpam_authctxt->valid &&
968             (sshpam_authctxt->pw->pw_uid != 0 ||
969             options.permit_root_login == PERMIT_YES)) {
970                 if ((r = sshbuf_put_cstring(buffer, *resp)) != 0)
971                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
972         } else {
973                 fake = fake_password(*resp);
974                 if ((r = sshbuf_put_cstring(buffer, fake)) != 0)
975                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
976                 free(fake);
977         }
978         if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, buffer) == -1) {
979                 sshbuf_free(buffer);
980                 return (-1);
981         }
982         sshbuf_free(buffer);
983         return (1);
984 }
985
986 static void
987 sshpam_free_ctx(void *ctxtp)
988 {
989         struct pam_ctxt *ctxt = ctxtp;
990
991         debug3("PAM: %s entering", __func__);
992         sshpam_thread_cleanup();
993         free(ctxt);
994         /*
995          * We don't call sshpam_cleanup() here because we may need the PAM
996          * handle at a later stage, e.g. when setting up a session.  It's
997          * still on the cleanup list, so pam_end() *will* be called before
998          * the server process terminates.
999          */
1000 }
1001
1002 KbdintDevice sshpam_device = {
1003         "pam",
1004         sshpam_init_ctx,
1005         sshpam_query,
1006         sshpam_respond,
1007         sshpam_free_ctx
1008 };
1009
1010 KbdintDevice mm_sshpam_device = {
1011         "pam",
1012         mm_sshpam_init_ctx,
1013         mm_sshpam_query,
1014         mm_sshpam_respond,
1015         mm_sshpam_free_ctx
1016 };
1017
1018 /*
1019  * This replaces auth-pam.c
1020  */
1021 void
1022 start_pam(struct ssh *ssh)
1023 {
1024         Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1025
1026         if (!options.use_pam)
1027                 fatal("PAM: initialisation requested when UsePAM=no");
1028
1029         if (sshpam_init(ssh, authctxt) == -1)
1030                 fatal("PAM: initialisation failed");
1031 }
1032
1033 void
1034 finish_pam(void)
1035 {
1036         sshpam_cleanup();
1037 }
1038
1039
1040 u_int
1041 do_pam_account(void)
1042 {
1043         debug("%s: called", __func__);
1044         if (sshpam_account_status != -1)
1045                 return (sshpam_account_status);
1046
1047         expose_authinfo(__func__);
1048
1049         sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
1050         debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
1051             pam_strerror(sshpam_handle, sshpam_err));
1052
1053         if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
1054                 sshpam_account_status = 0;
1055                 return (sshpam_account_status);
1056         }
1057
1058         if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
1059                 sshpam_password_change_required(1);
1060
1061         sshpam_account_status = 1;
1062         return (sshpam_account_status);
1063 }
1064
1065 void
1066 do_pam_setcred(int init)
1067 {
1068         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1069             (const void *)&store_conv);
1070         if (sshpam_err != PAM_SUCCESS)
1071                 fatal("PAM: failed to set PAM_CONV: %s",
1072                     pam_strerror(sshpam_handle, sshpam_err));
1073         if (init) {
1074                 debug("PAM: establishing credentials");
1075                 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
1076         } else {
1077                 debug("PAM: reinitializing credentials");
1078                 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
1079         }
1080         if (sshpam_err == PAM_SUCCESS) {
1081                 sshpam_cred_established = 1;
1082                 return;
1083         }
1084         if (sshpam_authenticated)
1085                 fatal("PAM: pam_setcred(): %s",
1086                     pam_strerror(sshpam_handle, sshpam_err));
1087         else
1088                 debug("PAM: pam_setcred(): %s",
1089                     pam_strerror(sshpam_handle, sshpam_err));
1090 }
1091
1092 static int
1093 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
1094     struct pam_response **resp, void *data)
1095 {
1096         char input[PAM_MAX_MSG_SIZE];
1097         struct pam_response *reply;
1098         int i;
1099
1100         debug3("PAM: %s called with %d messages", __func__, n);
1101
1102         *resp = NULL;
1103
1104         if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
1105                 return (PAM_CONV_ERR);
1106
1107         if ((reply = calloc(n, sizeof(*reply))) == NULL)
1108                 return (PAM_CONV_ERR);
1109
1110         for (i = 0; i < n; ++i) {
1111                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1112                 case PAM_PROMPT_ECHO_OFF:
1113                         reply[i].resp =
1114                             read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
1115                             RP_ALLOW_STDIN);
1116                         reply[i].resp_retcode = PAM_SUCCESS;
1117                         break;
1118                 case PAM_PROMPT_ECHO_ON:
1119                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1120                         if (fgets(input, sizeof input, stdin) == NULL)
1121                                 input[0] = '\0';
1122                         if ((reply[i].resp = strdup(input)) == NULL)
1123                                 goto fail;
1124                         reply[i].resp_retcode = PAM_SUCCESS;
1125                         break;
1126                 case PAM_ERROR_MSG:
1127                 case PAM_TEXT_INFO:
1128                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1129                         reply[i].resp_retcode = PAM_SUCCESS;
1130                         break;
1131                 default:
1132                         goto fail;
1133                 }
1134         }
1135         *resp = reply;
1136         return (PAM_SUCCESS);
1137
1138  fail:
1139         for(i = 0; i < n; i++) {
1140                 free(reply[i].resp);
1141         }
1142         free(reply);
1143         return (PAM_CONV_ERR);
1144 }
1145
1146 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
1147
1148 /*
1149  * XXX this should be done in the authentication phase, but ssh1 doesn't
1150  * support that
1151  */
1152 void
1153 do_pam_chauthtok(void)
1154 {
1155         if (use_privsep)
1156                 fatal("Password expired (unable to change with privsep)");
1157         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1158             (const void *)&tty_conv);
1159         if (sshpam_err != PAM_SUCCESS)
1160                 fatal("PAM: failed to set PAM_CONV: %s",
1161                     pam_strerror(sshpam_handle, sshpam_err));
1162         debug("PAM: changing password");
1163         sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
1164         if (sshpam_err != PAM_SUCCESS)
1165                 fatal("PAM: pam_chauthtok(): %s",
1166                     pam_strerror(sshpam_handle, sshpam_err));
1167 }
1168
1169 void
1170 do_pam_session(struct ssh *ssh)
1171 {
1172         debug3("PAM: opening session");
1173
1174         expose_authinfo(__func__);
1175
1176         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1177             (const void *)&store_conv);
1178         if (sshpam_err != PAM_SUCCESS)
1179                 fatal("PAM: failed to set PAM_CONV: %s",
1180                     pam_strerror(sshpam_handle, sshpam_err));
1181         sshpam_err = pam_open_session(sshpam_handle, 0);
1182         if (sshpam_err == PAM_SUCCESS)
1183                 sshpam_session_open = 1;
1184         else {
1185                 sshpam_session_open = 0;
1186                 auth_restrict_session(ssh);
1187                 error("PAM: pam_open_session(): %s",
1188                     pam_strerror(sshpam_handle, sshpam_err));
1189         }
1190
1191 }
1192
1193 int
1194 is_pam_session_open(void)
1195 {
1196         return sshpam_session_open;
1197 }
1198
1199 /*
1200  * Set a PAM environment string. We need to do this so that the session
1201  * modules can handle things like Kerberos/GSI credentials that appear
1202  * during the ssh authentication process.
1203  */
1204 int
1205 do_pam_putenv(char *name, char *value)
1206 {
1207         int ret = 1;
1208 #ifdef HAVE_PAM_PUTENV
1209         char *compound;
1210         size_t len;
1211
1212         len = strlen(name) + strlen(value) + 2;
1213         compound = xmalloc(len);
1214
1215         snprintf(compound, len, "%s=%s", name, value);
1216         ret = pam_putenv(sshpam_handle, compound);
1217         free(compound);
1218 #endif
1219
1220         return (ret);
1221 }
1222
1223 char **
1224 fetch_pam_child_environment(void)
1225 {
1226         return sshpam_env;
1227 }
1228
1229 char **
1230 fetch_pam_environment(void)
1231 {
1232         return (pam_getenvlist(sshpam_handle));
1233 }
1234
1235 void
1236 free_pam_environment(char **env)
1237 {
1238         char **envp;
1239
1240         if (env == NULL)
1241                 return;
1242
1243         for (envp = env; *envp; envp++)
1244                 free(*envp);
1245         free(env);
1246 }
1247
1248 /*
1249  * "Blind" conversation function for password authentication.  Assumes that
1250  * echo-off prompts are for the password and stores messages for later
1251  * display.
1252  */
1253 static int
1254 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1255     struct pam_response **resp, void *data)
1256 {
1257         struct pam_response *reply;
1258         int r, i;
1259         size_t len;
1260
1261         debug3("PAM: %s called with %d messages", __func__, n);
1262
1263         *resp = NULL;
1264
1265         if (n <= 0 || n > PAM_MAX_NUM_MSG)
1266                 return (PAM_CONV_ERR);
1267
1268         if ((reply = calloc(n, sizeof(*reply))) == NULL)
1269                 return (PAM_CONV_ERR);
1270
1271         for (i = 0; i < n; ++i) {
1272                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1273                 case PAM_PROMPT_ECHO_OFF:
1274                         if (sshpam_password == NULL)
1275                                 goto fail;
1276                         if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1277                                 goto fail;
1278                         reply[i].resp_retcode = PAM_SUCCESS;
1279                         break;
1280                 case PAM_ERROR_MSG:
1281                 case PAM_TEXT_INFO:
1282                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1283                         if (len > 0) {
1284                                 if ((r = sshbuf_putf(loginmsg, "%s\n",
1285                                     PAM_MSG_MEMBER(msg, i, msg))) != 0)
1286                                         fatal("%s: buffer error: %s",
1287                                             __func__, ssh_err(r));
1288                         }
1289                         if ((reply[i].resp = strdup("")) == NULL)
1290                                 goto fail;
1291                         reply[i].resp_retcode = PAM_SUCCESS;
1292                         break;
1293                 default:
1294                         goto fail;
1295                 }
1296         }
1297         *resp = reply;
1298         return (PAM_SUCCESS);
1299
1300  fail:
1301         for(i = 0; i < n; i++) {
1302                 free(reply[i].resp);
1303         }
1304         free(reply);
1305         return (PAM_CONV_ERR);
1306 }
1307
1308 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1309
1310 /*
1311  * Attempt password authentication via PAM
1312  */
1313 int
1314 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1315 {
1316         int flags = (options.permit_empty_passwd == 0 ?
1317             PAM_DISALLOW_NULL_AUTHTOK : 0);
1318         char *fake = NULL;
1319
1320         if (!options.use_pam || sshpam_handle == NULL)
1321                 fatal("PAM: %s called when PAM disabled or failed to "
1322                     "initialise.", __func__);
1323
1324         sshpam_password = password;
1325         sshpam_authctxt = authctxt;
1326
1327         /*
1328          * If the user logging in is invalid, or is root but is not permitted
1329          * by PermitRootLogin, use an invalid password to prevent leaking
1330          * information via timing (eg if the PAM config has a delay on fail).
1331          */
1332         if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1333             options.permit_root_login != PERMIT_YES))
1334                 sshpam_password = fake = fake_password(password);
1335
1336         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1337             (const void *)&passwd_conv);
1338         if (sshpam_err != PAM_SUCCESS)
1339                 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1340                     pam_strerror(sshpam_handle, sshpam_err));
1341
1342         sshpam_err = pam_authenticate(sshpam_handle, flags);
1343         sshpam_password = NULL;
1344         free(fake);
1345         if (sshpam_err == PAM_MAXTRIES)
1346                 sshpam_set_maxtries_reached(1);
1347         if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1348                 debug("PAM: password authentication accepted for %.100s",
1349                     authctxt->user);
1350                 return 1;
1351         } else {
1352                 debug("PAM: password authentication failed for %.100s: %s",
1353                     authctxt->valid ? authctxt->user : "an illegal user",
1354                     pam_strerror(sshpam_handle, sshpam_err));
1355                 return 0;
1356         }
1357 }
1358
1359 int
1360 sshpam_get_maxtries_reached(void)
1361 {
1362         return sshpam_maxtries_reached;
1363 }
1364
1365 void
1366 sshpam_set_maxtries_reached(int reached)
1367 {
1368         if (reached == 0 || sshpam_maxtries_reached)
1369                 return;
1370         sshpam_maxtries_reached = 1;
1371         options.password_authentication = 0;
1372         options.kbd_interactive_authentication = 0;
1373         options.challenge_response_authentication = 0;
1374 }
1375 #endif /* USE_PAM */