xref: /freebsd/crypto/openssh/auth-pam.c (revision 09d325677d53a12c79a43664ff29871e92247629)
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 Exp $ */
49 #include "includes.h"
50 
51 #include <sys/types.h>
52 #include <sys/stat.h>
53 #include <sys/wait.h>
54 
55 #include <errno.h>
56 #include <signal.h>
57 #include <stdarg.h>
58 #include <string.h>
59 #include <unistd.h>
60 
61 #ifdef USE_PAM
62 #if defined(HAVE_SECURITY_PAM_APPL_H)
63 #include <security/pam_appl.h>
64 #elif defined (HAVE_PAM_PAM_APPL_H)
65 #include <pam/pam_appl.h>
66 #endif
67 
68 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */
69 #ifdef PAM_SUN_CODEBASE
70 # define sshpam_const		/* Solaris, HP-UX, AIX */
71 #else
72 # define sshpam_const	const	/* LinuxPAM, OpenPAM */
73 #endif
74 
75 /* Ambiguity in spec: is it an array of pointers or a pointer to an array? */
76 #ifdef PAM_SUN_CODEBASE
77 # define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member)
78 #else
79 # define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member)
80 #endif
81 
82 #include "xmalloc.h"
83 #include "buffer.h"
84 #include "key.h"
85 #include "hostfile.h"
86 #include "auth.h"
87 #include "auth-pam.h"
88 #include "canohost.h"
89 #include "log.h"
90 #include "msg.h"
91 #include "packet.h"
92 #include "misc.h"
93 #include "servconf.h"
94 #include "ssh2.h"
95 #include "auth-options.h"
96 #ifdef GSSAPI
97 #include "ssh-gss.h"
98 #endif
99 #include "monitor_wrap.h"
100 
101 extern ServerOptions options;
102 extern Buffer loginmsg;
103 extern int compat20;
104 extern u_int utmp_len;
105 
106 /* so we don't silently change behaviour */
107 #ifdef USE_POSIX_THREADS
108 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
109 #endif
110 
111 /*
112  * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
113  * and generally a bad idea.  Use at own risk and do not expect support if
114  * this breaks.
115  */
116 #ifdef UNSUPPORTED_POSIX_THREADS_HACK
117 #include <pthread.h>
118 /*
119  * Avoid namespace clash when *not* using pthreads for systems *with*
120  * pthreads, which unconditionally define pthread_t via sys/types.h
121  * (e.g. Linux)
122  */
123 typedef pthread_t sp_pthread_t;
124 #else
125 typedef pid_t sp_pthread_t;
126 #endif
127 
128 struct pam_ctxt {
129 	sp_pthread_t	 pam_thread;
130 	int		 pam_psock;
131 	int		 pam_csock;
132 	int		 pam_done;
133 };
134 
135 static void sshpam_free_ctx(void *);
136 static struct pam_ctxt *cleanup_ctxt;
137 
138 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
139 /*
140  * Simulate threads with processes.
141  */
142 
143 static int sshpam_thread_status = -1;
144 static mysig_t sshpam_oldsig;
145 
146 static void
147 sshpam_sigchld_handler(int sig)
148 {
149 	signal(SIGCHLD, SIG_DFL);
150 	if (cleanup_ctxt == NULL)
151 		return;	/* handler called after PAM cleanup, shouldn't happen */
152 	if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
153 	    <= 0) {
154 		/* PAM thread has not exitted, privsep slave must have */
155 		kill(cleanup_ctxt->pam_thread, SIGTERM);
156 		if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0)
157 		    <= 0)
158 			return; /* could not wait */
159 	}
160 	if (WIFSIGNALED(sshpam_thread_status) &&
161 	    WTERMSIG(sshpam_thread_status) == SIGTERM)
162 		return;	/* terminated by pthread_cancel */
163 	if (!WIFEXITED(sshpam_thread_status))
164 		sigdie("PAM: authentication thread exited unexpectedly");
165 	if (WEXITSTATUS(sshpam_thread_status) != 0)
166 		sigdie("PAM: authentication thread exited uncleanly");
167 }
168 
169 /* ARGSUSED */
170 static void
171 pthread_exit(void *value)
172 {
173 	_exit(0);
174 }
175 
176 /* ARGSUSED */
177 static int
178 pthread_create(sp_pthread_t *thread, const void *attr,
179     void *(*thread_start)(void *), void *arg)
180 {
181 	pid_t pid;
182 	struct pam_ctxt *ctx = arg;
183 
184 	sshpam_thread_status = -1;
185 	switch ((pid = fork())) {
186 	case -1:
187 		error("fork(): %s", strerror(errno));
188 		return (-1);
189 	case 0:
190 		close(ctx->pam_psock);
191 		ctx->pam_psock = -1;
192 		thread_start(arg);
193 		_exit(1);
194 	default:
195 		*thread = pid;
196 		close(ctx->pam_csock);
197 		ctx->pam_csock = -1;
198 		sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
199 		return (0);
200 	}
201 }
202 
203 static int
204 pthread_cancel(sp_pthread_t thread)
205 {
206 	signal(SIGCHLD, sshpam_oldsig);
207 	return (kill(thread, SIGTERM));
208 }
209 
210 /* ARGSUSED */
211 static int
212 pthread_join(sp_pthread_t thread, void **value)
213 {
214 	int status;
215 
216 	if (sshpam_thread_status != -1)
217 		return (sshpam_thread_status);
218 	signal(SIGCHLD, sshpam_oldsig);
219 	waitpid(thread, &status, 0);
220 	return (status);
221 }
222 #endif
223 
224 
225 static pam_handle_t *sshpam_handle = NULL;
226 static int sshpam_err = 0;
227 static int sshpam_authenticated = 0;
228 static int sshpam_session_open = 0;
229 static int sshpam_cred_established = 0;
230 static int sshpam_account_status = -1;
231 static char **sshpam_env = NULL;
232 static Authctxt *sshpam_authctxt = NULL;
233 static const char *sshpam_password = NULL;
234 static char badpw[] = "\b\n\r\177INCORRECT";
235 
236 /* Some PAM implementations don't implement this */
237 #ifndef HAVE_PAM_GETENVLIST
238 static char **
239 pam_getenvlist(pam_handle_t *pamh)
240 {
241 	/*
242 	 * XXX - If necessary, we can still support envrionment passing
243 	 * for platforms without pam_getenvlist by searching for known
244 	 * env vars (e.g. KRB5CCNAME) from the PAM environment.
245 	 */
246 	 return NULL;
247 }
248 #endif
249 
250 /*
251  * Some platforms, notably Solaris, do not enforce password complexity
252  * rules during pam_chauthtok() if the real uid of the calling process
253  * is 0, on the assumption that it's being called by "passwd" run by root.
254  * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
255  * the right thing.
256  */
257 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
258 static int
259 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
260 {
261 	int result;
262 
263 	if (sshpam_authctxt == NULL)
264 		fatal("PAM: sshpam_authctxt not initialized");
265 	if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
266 		fatal("%s: setreuid failed: %s", __func__, strerror(errno));
267 	result = pam_chauthtok(pamh, flags);
268 	if (setreuid(0, -1) == -1)
269 		fatal("%s: setreuid failed: %s", __func__, strerror(errno));
270 	return result;
271 }
272 # define pam_chauthtok(a,b)	(sshpam_chauthtok_ruid((a), (b)))
273 #endif
274 
275 void
276 sshpam_password_change_required(int reqd)
277 {
278 	debug3("%s %d", __func__, reqd);
279 	if (sshpam_authctxt == NULL)
280 		fatal("%s: PAM authctxt not initialized", __func__);
281 	sshpam_authctxt->force_pwchange = reqd;
282 	if (reqd) {
283 		no_port_forwarding_flag |= 2;
284 		no_agent_forwarding_flag |= 2;
285 		no_x11_forwarding_flag |= 2;
286 	} else {
287 		no_port_forwarding_flag &= ~2;
288 		no_agent_forwarding_flag &= ~2;
289 		no_x11_forwarding_flag &= ~2;
290 	}
291 }
292 
293 /* Import regular and PAM environment from subprocess */
294 static void
295 import_environments(Buffer *b)
296 {
297 	char *env;
298 	u_int i, num_env;
299 	int err;
300 
301 	debug3("PAM: %s entering", __func__);
302 
303 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
304 	/* Import variables set by do_pam_account */
305 	sshpam_account_status = buffer_get_int(b);
306 	sshpam_password_change_required(buffer_get_int(b));
307 
308 	/* Import environment from subprocess */
309 	num_env = buffer_get_int(b);
310 	if (num_env > 1024)
311 		fatal("%s: received %u environment variables, expected <= 1024",
312 		    __func__, num_env);
313 	sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env));
314 	debug3("PAM: num env strings %d", num_env);
315 	for(i = 0; i < num_env; i++)
316 		sshpam_env[i] = buffer_get_string(b, NULL);
317 
318 	sshpam_env[num_env] = NULL;
319 
320 	/* Import PAM environment from subprocess */
321 	num_env = buffer_get_int(b);
322 	debug("PAM: num PAM env strings %d", num_env);
323 	for(i = 0; i < num_env; i++) {
324 		env = buffer_get_string(b, NULL);
325 
326 #ifdef HAVE_PAM_PUTENV
327 		/* Errors are not fatal here */
328 		if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
329 			error("PAM: pam_putenv: %s",
330 			    pam_strerror(sshpam_handle, sshpam_err));
331 		}
332 #endif
333 	}
334 #endif
335 }
336 
337 /*
338  * Conversation function for authentication thread.
339  */
340 static int
341 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
342     struct pam_response **resp, void *data)
343 {
344 	Buffer buffer;
345 	struct pam_ctxt *ctxt;
346 	struct pam_response *reply;
347 	int i;
348 
349 	debug3("PAM: %s entering, %d messages", __func__, n);
350 	*resp = NULL;
351 
352 	if (data == NULL) {
353 		error("PAM: conversation function passed a null context");
354 		return (PAM_CONV_ERR);
355 	}
356 	ctxt = data;
357 	if (n <= 0 || n > PAM_MAX_NUM_MSG)
358 		return (PAM_CONV_ERR);
359 
360 	if ((reply = calloc(n, sizeof(*reply))) == NULL)
361 		return (PAM_CONV_ERR);
362 
363 	buffer_init(&buffer);
364 	for (i = 0; i < n; ++i) {
365 		switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
366 		case PAM_PROMPT_ECHO_OFF:
367 			buffer_put_cstring(&buffer,
368 			    PAM_MSG_MEMBER(msg, i, msg));
369 			if (ssh_msg_send(ctxt->pam_csock,
370 			    PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
371 				goto fail;
372 			if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
373 				goto fail;
374 			if (buffer_get_char(&buffer) != PAM_AUTHTOK)
375 				goto fail;
376 			reply[i].resp = buffer_get_string(&buffer, NULL);
377 			break;
378 		case PAM_PROMPT_ECHO_ON:
379 			buffer_put_cstring(&buffer,
380 			    PAM_MSG_MEMBER(msg, i, msg));
381 			if (ssh_msg_send(ctxt->pam_csock,
382 			    PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
383 				goto fail;
384 			if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
385 				goto fail;
386 			if (buffer_get_char(&buffer) != PAM_AUTHTOK)
387 				goto fail;
388 			reply[i].resp = buffer_get_string(&buffer, NULL);
389 			break;
390 		case PAM_ERROR_MSG:
391 			buffer_put_cstring(&buffer,
392 			    PAM_MSG_MEMBER(msg, i, msg));
393 			if (ssh_msg_send(ctxt->pam_csock,
394 			    PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
395 				goto fail;
396 			break;
397 		case PAM_TEXT_INFO:
398 			buffer_put_cstring(&buffer,
399 			    PAM_MSG_MEMBER(msg, i, msg));
400 			if (ssh_msg_send(ctxt->pam_csock,
401 			    PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
402 				goto fail;
403 			break;
404 		default:
405 			goto fail;
406 		}
407 		buffer_clear(&buffer);
408 	}
409 	buffer_free(&buffer);
410 	*resp = reply;
411 	return (PAM_SUCCESS);
412 
413  fail:
414 	for(i = 0; i < n; i++) {
415 		free(reply[i].resp);
416 	}
417 	free(reply);
418 	buffer_free(&buffer);
419 	return (PAM_CONV_ERR);
420 }
421 
422 /*
423  * Authentication thread.
424  */
425 static void *
426 sshpam_thread(void *ctxtp)
427 {
428 	struct pam_ctxt *ctxt = ctxtp;
429 	Buffer buffer;
430 	struct pam_conv sshpam_conv;
431 	int flags = (options.permit_empty_passwd == 0 ?
432 	    PAM_DISALLOW_NULL_AUTHTOK : 0);
433 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
434 	extern char **environ;
435 	char **env_from_pam;
436 	u_int i;
437 	const char *pam_user;
438 	const char **ptr_pam_user = &pam_user;
439 	char *tz = getenv("TZ");
440 
441 	pam_get_item(sshpam_handle, PAM_USER,
442 	    (sshpam_const void **)ptr_pam_user);
443 
444 	environ[0] = NULL;
445 	if (tz != NULL)
446 		if (setenv("TZ", tz, 1) == -1)
447 			error("PAM: could not set TZ environment: %s",
448 			    strerror(errno));
449 
450 	if (sshpam_authctxt != NULL) {
451 		setproctitle("%s [pam]",
452 		    sshpam_authctxt->valid ? pam_user : "unknown");
453 	}
454 #endif
455 
456 	sshpam_conv.conv = sshpam_thread_conv;
457 	sshpam_conv.appdata_ptr = ctxt;
458 
459 	if (sshpam_authctxt == NULL)
460 		fatal("%s: PAM authctxt not initialized", __func__);
461 
462 	buffer_init(&buffer);
463 	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
464 	    (const void *)&sshpam_conv);
465 	if (sshpam_err != PAM_SUCCESS)
466 		goto auth_fail;
467 	sshpam_err = pam_authenticate(sshpam_handle, flags);
468 	if (sshpam_err != PAM_SUCCESS)
469 		goto auth_fail;
470 
471 	if (compat20) {
472 		if (!do_pam_account()) {
473 			sshpam_err = PAM_ACCT_EXPIRED;
474 			goto auth_fail;
475 		}
476 		if (sshpam_authctxt->force_pwchange) {
477 			sshpam_err = pam_chauthtok(sshpam_handle,
478 			    PAM_CHANGE_EXPIRED_AUTHTOK);
479 			if (sshpam_err != PAM_SUCCESS)
480 				goto auth_fail;
481 			sshpam_password_change_required(0);
482 		}
483 	}
484 
485 	buffer_put_cstring(&buffer, "OK");
486 
487 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
488 	/* Export variables set by do_pam_account */
489 	buffer_put_int(&buffer, sshpam_account_status);
490 	buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);
491 
492 	/* Export any environment strings set in child */
493 	for(i = 0; environ[i] != NULL; i++)
494 		; /* Count */
495 	buffer_put_int(&buffer, i);
496 	for(i = 0; environ[i] != NULL; i++)
497 		buffer_put_cstring(&buffer, environ[i]);
498 
499 	/* Export any environment strings set by PAM in child */
500 	env_from_pam = pam_getenvlist(sshpam_handle);
501 	for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
502 		; /* Count */
503 	buffer_put_int(&buffer, i);
504 	for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
505 		buffer_put_cstring(&buffer, env_from_pam[i]);
506 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */
507 
508 	/* XXX - can't do much about an error here */
509 	ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
510 	buffer_free(&buffer);
511 	pthread_exit(NULL);
512 
513  auth_fail:
514 	buffer_put_cstring(&buffer,
515 	    pam_strerror(sshpam_handle, sshpam_err));
516 	/* XXX - can't do much about an error here */
517 	if (sshpam_err == PAM_ACCT_EXPIRED)
518 		ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, &buffer);
519 	else
520 		ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
521 	buffer_free(&buffer);
522 	pthread_exit(NULL);
523 
524 	return (NULL); /* Avoid warning for non-pthread case */
525 }
526 
527 void
528 sshpam_thread_cleanup(void)
529 {
530 	struct pam_ctxt *ctxt = cleanup_ctxt;
531 
532 	debug3("PAM: %s entering", __func__);
533 	if (ctxt != NULL && ctxt->pam_thread != 0) {
534 		pthread_cancel(ctxt->pam_thread);
535 		pthread_join(ctxt->pam_thread, NULL);
536 		close(ctxt->pam_psock);
537 		close(ctxt->pam_csock);
538 		memset(ctxt, 0, sizeof(*ctxt));
539 		cleanup_ctxt = NULL;
540 	}
541 }
542 
543 static int
544 sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
545     struct pam_response **resp, void *data)
546 {
547 	debug3("PAM: %s entering, %d messages", __func__, n);
548 	return (PAM_CONV_ERR);
549 }
550 
551 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
552 
553 static int
554 sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
555     struct pam_response **resp, void *data)
556 {
557 	struct pam_response *reply;
558 	int i;
559 	size_t len;
560 
561 	debug3("PAM: %s called with %d messages", __func__, n);
562 	*resp = NULL;
563 
564 	if (n <= 0 || n > PAM_MAX_NUM_MSG)
565 		return (PAM_CONV_ERR);
566 
567 	if ((reply = calloc(n, sizeof(*reply))) == NULL)
568 		return (PAM_CONV_ERR);
569 
570 	for (i = 0; i < n; ++i) {
571 		switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
572 		case PAM_ERROR_MSG:
573 		case PAM_TEXT_INFO:
574 			len = strlen(PAM_MSG_MEMBER(msg, i, msg));
575 			buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
576 			buffer_append(&loginmsg, "\n", 1 );
577 			reply[i].resp_retcode = PAM_SUCCESS;
578 			break;
579 		default:
580 			goto fail;
581 		}
582 	}
583 	*resp = reply;
584 	return (PAM_SUCCESS);
585 
586  fail:
587 	for(i = 0; i < n; i++) {
588 		free(reply[i].resp);
589 	}
590 	free(reply);
591 	return (PAM_CONV_ERR);
592 }
593 
594 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
595 
596 void
597 sshpam_cleanup(void)
598 {
599 	if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor()))
600 		return;
601 	debug("PAM: cleanup");
602 	pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
603 	if (sshpam_session_open) {
604 		debug("PAM: closing session");
605 		pam_close_session(sshpam_handle, PAM_SILENT);
606 		sshpam_session_open = 0;
607 	}
608 	if (sshpam_cred_established) {
609 		debug("PAM: deleting credentials");
610 		pam_setcred(sshpam_handle, PAM_DELETE_CRED);
611 		sshpam_cred_established = 0;
612 	}
613 	sshpam_authenticated = 0;
614 	pam_end(sshpam_handle, sshpam_err);
615 	sshpam_handle = NULL;
616 }
617 
618 static int
619 sshpam_init(Authctxt *authctxt)
620 {
621 	extern char *__progname;
622 	const char *pam_rhost, *pam_user, *user = authctxt->user;
623 	const char **ptr_pam_user = &pam_user;
624 
625 	if (sshpam_handle != NULL) {
626 		/* We already have a PAM context; check if the user matches */
627 		sshpam_err = pam_get_item(sshpam_handle,
628 		    PAM_USER, (sshpam_const void **)ptr_pam_user);
629 		if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
630 			return (0);
631 		pam_end(sshpam_handle, sshpam_err);
632 		sshpam_handle = NULL;
633 	}
634 	debug("PAM: initializing for \"%s\"", user);
635 	sshpam_err =
636 	    pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
637 	sshpam_authctxt = authctxt;
638 
639 	if (sshpam_err != PAM_SUCCESS) {
640 		pam_end(sshpam_handle, sshpam_err);
641 		sshpam_handle = NULL;
642 		return (-1);
643 	}
644 	pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
645 	debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
646 	sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
647 	if (sshpam_err != PAM_SUCCESS) {
648 		pam_end(sshpam_handle, sshpam_err);
649 		sshpam_handle = NULL;
650 		return (-1);
651 	}
652 #ifdef PAM_TTY_KLUDGE
653 	/*
654 	 * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
655 	 * sshd doesn't set the tty until too late in the auth process and
656 	 * may not even set one (for tty-less connections)
657 	 */
658 	debug("PAM: setting PAM_TTY to \"ssh\"");
659 	sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
660 	if (sshpam_err != PAM_SUCCESS) {
661 		pam_end(sshpam_handle, sshpam_err);
662 		sshpam_handle = NULL;
663 		return (-1);
664 	}
665 #endif
666 	return (0);
667 }
668 
669 static void *
670 sshpam_init_ctx(Authctxt *authctxt)
671 {
672 	struct pam_ctxt *ctxt;
673 	int socks[2];
674 
675 	debug3("PAM: %s entering", __func__);
676 	/*
677 	 * Refuse to start if we don't have PAM enabled or do_pam_account
678 	 * has previously failed.
679 	 */
680 	if (!options.use_pam || sshpam_account_status == 0)
681 		return NULL;
682 
683 	/* Initialize PAM */
684 	if (sshpam_init(authctxt) == -1) {
685 		error("PAM: initialization failed");
686 		return (NULL);
687 	}
688 
689 	ctxt = xcalloc(1, sizeof *ctxt);
690 
691 	/* Start the authentication thread */
692 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
693 		error("PAM: failed create sockets: %s", strerror(errno));
694 		free(ctxt);
695 		return (NULL);
696 	}
697 	ctxt->pam_psock = socks[0];
698 	ctxt->pam_csock = socks[1];
699 	if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
700 		error("PAM: failed to start authentication thread: %s",
701 		    strerror(errno));
702 		close(socks[0]);
703 		close(socks[1]);
704 		free(ctxt);
705 		return (NULL);
706 	}
707 	cleanup_ctxt = ctxt;
708 	return (ctxt);
709 }
710 
711 static int
712 sshpam_query(void *ctx, char **name, char **info,
713     u_int *num, char ***prompts, u_int **echo_on)
714 {
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;
739 			**prompts = xrealloc(**prompts, 1, len);
740 			strlcpy(**prompts + plen, msg, len - plen);
741 			plen += mlen;
742 			**echo_on = (type == PAM_PROMPT_ECHO_ON);
743 			free(msg);
744 			return (0);
745 		case PAM_ERROR_MSG:
746 		case PAM_TEXT_INFO:
747 			/* accumulate messages */
748 			len = plen + mlen + 2;
749 			**prompts = xrealloc(**prompts, 1, len);
750 			strlcpy(**prompts + plen, msg, len - plen);
751 			plen += mlen;
752 			strlcat(**prompts + plen, "\n", len - plen);
753 			plen++;
754 			free(msg);
755 			break;
756 		case PAM_ACCT_EXPIRED:
757 			sshpam_account_status = 0;
758 			/* FALLTHROUGH */
759 		case PAM_AUTH_ERR:
760 			debug3("PAM: %s", pam_strerror(sshpam_handle, type));
761 			if (**prompts != NULL && strlen(**prompts) != 0) {
762 				*info = **prompts;
763 				**prompts = NULL;
764 				*num = 0;
765 				**echo_on = 0;
766 				ctxt->pam_done = -1;
767 				free(msg);
768 				return 0;
769 			}
770 			/* FALLTHROUGH */
771 		case PAM_SUCCESS:
772 			if (**prompts != NULL) {
773 				/* drain any accumulated messages */
774 				debug("PAM: %s", **prompts);
775 				buffer_append(&loginmsg, **prompts,
776 				    strlen(**prompts));
777 				free(**prompts);
778 				**prompts = NULL;
779 			}
780 			if (type == PAM_SUCCESS) {
781 				if (!sshpam_authctxt->valid ||
782 				    (sshpam_authctxt->pw->pw_uid == 0 &&
783 				    options.permit_root_login != PERMIT_YES))
784 					fatal("Internal error: PAM auth "
785 					    "succeeded when it should have "
786 					    "failed");
787 				import_environments(&buffer);
788 				*num = 0;
789 				**echo_on = 0;
790 				ctxt->pam_done = 1;
791 				free(msg);
792 				return (0);
793 			}
794 			error("PAM: %s for %s%.100s from %.100s", msg,
795 			    sshpam_authctxt->valid ? "" : "illegal user ",
796 			    sshpam_authctxt->user,
797 			    get_remote_name_or_ip(utmp_len, options.use_dns));
798 			/* FALLTHROUGH */
799 		default:
800 			*num = 0;
801 			**echo_on = 0;
802 			free(msg);
803 			ctxt->pam_done = -1;
804 			return (-1);
805 		}
806 	}
807 	return (-1);
808 }
809 
810 /* XXX - see also comment in auth-chall.c:verify_response */
811 static int
812 sshpam_respond(void *ctx, u_int num, char **resp)
813 {
814 	Buffer buffer;
815 	struct pam_ctxt *ctxt = ctx;
816 
817 	debug2("PAM: %s entering, %u responses", __func__, num);
818 	switch (ctxt->pam_done) {
819 	case 1:
820 		sshpam_authenticated = 1;
821 		return (0);
822 	case 0:
823 		break;
824 	default:
825 		return (-1);
826 	}
827 	if (num != 1) {
828 		error("PAM: expected one response, got %u", num);
829 		return (-1);
830 	}
831 	buffer_init(&buffer);
832 	if (sshpam_authctxt->valid &&
833 	    (sshpam_authctxt->pw->pw_uid != 0 ||
834 	    options.permit_root_login == PERMIT_YES))
835 		buffer_put_cstring(&buffer, *resp);
836 	else
837 		buffer_put_cstring(&buffer, badpw);
838 	if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
839 		buffer_free(&buffer);
840 		return (-1);
841 	}
842 	buffer_free(&buffer);
843 	return (1);
844 }
845 
846 static void
847 sshpam_free_ctx(void *ctxtp)
848 {
849 	struct pam_ctxt *ctxt = ctxtp;
850 
851 	debug3("PAM: %s entering", __func__);
852 	sshpam_thread_cleanup();
853 	free(ctxt);
854 	/*
855 	 * We don't call sshpam_cleanup() here because we may need the PAM
856 	 * handle at a later stage, e.g. when setting up a session.  It's
857 	 * still on the cleanup list, so pam_end() *will* be called before
858 	 * the server process terminates.
859 	 */
860 }
861 
862 KbdintDevice sshpam_device = {
863 	"pam",
864 	sshpam_init_ctx,
865 	sshpam_query,
866 	sshpam_respond,
867 	sshpam_free_ctx
868 };
869 
870 KbdintDevice mm_sshpam_device = {
871 	"pam",
872 	mm_sshpam_init_ctx,
873 	mm_sshpam_query,
874 	mm_sshpam_respond,
875 	mm_sshpam_free_ctx
876 };
877 
878 /*
879  * This replaces auth-pam.c
880  */
881 void
882 start_pam(Authctxt *authctxt)
883 {
884 	if (!options.use_pam)
885 		fatal("PAM: initialisation requested when UsePAM=no");
886 
887 	if (sshpam_init(authctxt) == -1)
888 		fatal("PAM: initialisation failed");
889 }
890 
891 void
892 finish_pam(void)
893 {
894 	sshpam_cleanup();
895 }
896 
897 u_int
898 do_pam_account(void)
899 {
900 	debug("%s: called", __func__);
901 	if (sshpam_account_status != -1)
902 		return (sshpam_account_status);
903 
904 	sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
905 	debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
906 	    pam_strerror(sshpam_handle, sshpam_err));
907 
908 	if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
909 		sshpam_account_status = 0;
910 		return (sshpam_account_status);
911 	}
912 
913 	if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
914 		sshpam_password_change_required(1);
915 
916 	sshpam_account_status = 1;
917 	return (sshpam_account_status);
918 }
919 
920 void
921 do_pam_set_tty(const char *tty)
922 {
923 	if (tty != NULL) {
924 		debug("PAM: setting PAM_TTY to \"%s\"", tty);
925 		sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
926 		if (sshpam_err != PAM_SUCCESS)
927 			fatal("PAM: failed to set PAM_TTY: %s",
928 			    pam_strerror(sshpam_handle, sshpam_err));
929 	}
930 }
931 
932 void
933 do_pam_setcred(int init)
934 {
935 	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
936 	    (const void *)&store_conv);
937 	if (sshpam_err != PAM_SUCCESS)
938 		fatal("PAM: failed to set PAM_CONV: %s",
939 		    pam_strerror(sshpam_handle, sshpam_err));
940 	if (init) {
941 		debug("PAM: establishing credentials");
942 		sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
943 	} else {
944 		debug("PAM: reinitializing credentials");
945 		sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
946 	}
947 	if (sshpam_err == PAM_SUCCESS) {
948 		sshpam_cred_established = 1;
949 		return;
950 	}
951 	if (sshpam_authenticated)
952 		fatal("PAM: pam_setcred(): %s",
953 		    pam_strerror(sshpam_handle, sshpam_err));
954 	else
955 		debug("PAM: pam_setcred(): %s",
956 		    pam_strerror(sshpam_handle, sshpam_err));
957 }
958 
959 static int
960 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
961     struct pam_response **resp, void *data)
962 {
963 	char input[PAM_MAX_MSG_SIZE];
964 	struct pam_response *reply;
965 	int i;
966 
967 	debug3("PAM: %s called with %d messages", __func__, n);
968 
969 	*resp = NULL;
970 
971 	if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
972 		return (PAM_CONV_ERR);
973 
974 	if ((reply = calloc(n, sizeof(*reply))) == NULL)
975 		return (PAM_CONV_ERR);
976 
977 	for (i = 0; i < n; ++i) {
978 		switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
979 		case PAM_PROMPT_ECHO_OFF:
980 			reply[i].resp =
981 			    read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
982 			    RP_ALLOW_STDIN);
983 			reply[i].resp_retcode = PAM_SUCCESS;
984 			break;
985 		case PAM_PROMPT_ECHO_ON:
986 			fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
987 			if (fgets(input, sizeof input, stdin) == NULL)
988 				input[0] = '\0';
989 			if ((reply[i].resp = strdup(input)) == NULL)
990 				goto fail;
991 			reply[i].resp_retcode = PAM_SUCCESS;
992 			break;
993 		case PAM_ERROR_MSG:
994 		case PAM_TEXT_INFO:
995 			fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
996 			reply[i].resp_retcode = PAM_SUCCESS;
997 			break;
998 		default:
999 			goto fail;
1000 		}
1001 	}
1002 	*resp = reply;
1003 	return (PAM_SUCCESS);
1004 
1005  fail:
1006 	for(i = 0; i < n; i++) {
1007 		free(reply[i].resp);
1008 	}
1009 	free(reply);
1010 	return (PAM_CONV_ERR);
1011 }
1012 
1013 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
1014 
1015 /*
1016  * XXX this should be done in the authentication phase, but ssh1 doesn't
1017  * support that
1018  */
1019 void
1020 do_pam_chauthtok(void)
1021 {
1022 	if (use_privsep)
1023 		fatal("Password expired (unable to change with privsep)");
1024 	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1025 	    (const void *)&tty_conv);
1026 	if (sshpam_err != PAM_SUCCESS)
1027 		fatal("PAM: failed to set PAM_CONV: %s",
1028 		    pam_strerror(sshpam_handle, sshpam_err));
1029 	debug("PAM: changing password");
1030 	sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
1031 	if (sshpam_err != PAM_SUCCESS)
1032 		fatal("PAM: pam_chauthtok(): %s",
1033 		    pam_strerror(sshpam_handle, sshpam_err));
1034 }
1035 
1036 void
1037 do_pam_session(void)
1038 {
1039 	debug3("PAM: opening session");
1040 	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1041 	    (const void *)&store_conv);
1042 	if (sshpam_err != PAM_SUCCESS)
1043 		fatal("PAM: failed to set PAM_CONV: %s",
1044 		    pam_strerror(sshpam_handle, sshpam_err));
1045 	sshpam_err = pam_open_session(sshpam_handle, 0);
1046 	if (sshpam_err == PAM_SUCCESS)
1047 		sshpam_session_open = 1;
1048 	else {
1049 		sshpam_session_open = 0;
1050 		disable_forwarding();
1051 		error("PAM: pam_open_session(): %s",
1052 		    pam_strerror(sshpam_handle, sshpam_err));
1053 	}
1054 
1055 }
1056 
1057 int
1058 is_pam_session_open(void)
1059 {
1060 	return sshpam_session_open;
1061 }
1062 
1063 /*
1064  * Set a PAM environment string. We need to do this so that the session
1065  * modules can handle things like Kerberos/GSI credentials that appear
1066  * during the ssh authentication process.
1067  */
1068 int
1069 do_pam_putenv(char *name, char *value)
1070 {
1071 	int ret = 1;
1072 #ifdef HAVE_PAM_PUTENV
1073 	char *compound;
1074 	size_t len;
1075 
1076 	len = strlen(name) + strlen(value) + 2;
1077 	compound = xmalloc(len);
1078 
1079 	snprintf(compound, len, "%s=%s", name, value);
1080 	ret = pam_putenv(sshpam_handle, compound);
1081 	free(compound);
1082 #endif
1083 
1084 	return (ret);
1085 }
1086 
1087 char **
1088 fetch_pam_child_environment(void)
1089 {
1090 	return sshpam_env;
1091 }
1092 
1093 char **
1094 fetch_pam_environment(void)
1095 {
1096 	return (pam_getenvlist(sshpam_handle));
1097 }
1098 
1099 void
1100 free_pam_environment(char **env)
1101 {
1102 	char **envp;
1103 
1104 	if (env == NULL)
1105 		return;
1106 
1107 	for (envp = env; *envp; envp++)
1108 		free(*envp);
1109 	free(env);
1110 }
1111 
1112 /*
1113  * "Blind" conversation function for password authentication.  Assumes that
1114  * echo-off prompts are for the password and stores messages for later
1115  * display.
1116  */
1117 static int
1118 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1119     struct pam_response **resp, void *data)
1120 {
1121 	struct pam_response *reply;
1122 	int i;
1123 	size_t len;
1124 
1125 	debug3("PAM: %s called with %d messages", __func__, n);
1126 
1127 	*resp = NULL;
1128 
1129 	if (n <= 0 || n > PAM_MAX_NUM_MSG)
1130 		return (PAM_CONV_ERR);
1131 
1132 	if ((reply = calloc(n, sizeof(*reply))) == NULL)
1133 		return (PAM_CONV_ERR);
1134 
1135 	for (i = 0; i < n; ++i) {
1136 		switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1137 		case PAM_PROMPT_ECHO_OFF:
1138 			if (sshpam_password == NULL)
1139 				goto fail;
1140 			if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1141 				goto fail;
1142 			reply[i].resp_retcode = PAM_SUCCESS;
1143 			break;
1144 		case PAM_ERROR_MSG:
1145 		case PAM_TEXT_INFO:
1146 			len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1147 			if (len > 0) {
1148 				buffer_append(&loginmsg,
1149 				    PAM_MSG_MEMBER(msg, i, msg), len);
1150 				buffer_append(&loginmsg, "\n", 1);
1151 			}
1152 			if ((reply[i].resp = strdup("")) == NULL)
1153 				goto fail;
1154 			reply[i].resp_retcode = PAM_SUCCESS;
1155 			break;
1156 		default:
1157 			goto fail;
1158 		}
1159 	}
1160 	*resp = reply;
1161 	return (PAM_SUCCESS);
1162 
1163  fail:
1164 	for(i = 0; i < n; i++) {
1165 		free(reply[i].resp);
1166 	}
1167 	free(reply);
1168 	return (PAM_CONV_ERR);
1169 }
1170 
1171 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1172 
1173 /*
1174  * Attempt password authentication via PAM
1175  */
1176 int
1177 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1178 {
1179 	int flags = (options.permit_empty_passwd == 0 ?
1180 	    PAM_DISALLOW_NULL_AUTHTOK : 0);
1181 
1182 	if (!options.use_pam || sshpam_handle == NULL)
1183 		fatal("PAM: %s called when PAM disabled or failed to "
1184 		    "initialise.", __func__);
1185 
1186 	sshpam_password = password;
1187 	sshpam_authctxt = authctxt;
1188 
1189 	/*
1190 	 * If the user logging in is invalid, or is root but is not permitted
1191 	 * by PermitRootLogin, use an invalid password to prevent leaking
1192 	 * information via timing (eg if the PAM config has a delay on fail).
1193 	 */
1194 	if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1195 	    options.permit_root_login != PERMIT_YES))
1196 		sshpam_password = badpw;
1197 
1198 	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1199 	    (const void *)&passwd_conv);
1200 	if (sshpam_err != PAM_SUCCESS)
1201 		fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1202 		    pam_strerror(sshpam_handle, sshpam_err));
1203 
1204 	sshpam_err = pam_authenticate(sshpam_handle, flags);
1205 	sshpam_password = NULL;
1206 	if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1207 		debug("PAM: password authentication accepted for %.100s",
1208 		    authctxt->user);
1209 		return 1;
1210 	} else {
1211 		debug("PAM: password authentication failed for %.100s: %s",
1212 		    authctxt->valid ? authctxt->user : "an illegal user",
1213 		    pam_strerror(sshpam_handle, sshpam_err));
1214 		return 0;
1215 	}
1216 }
1217 #endif /* USE_PAM */
1218