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
101extern ServerOptions options;
102extern Buffer loginmsg;
103extern int compat20;
104extern 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 */
123typedef pthread_t sp_pthread_t;
124#else
125typedef pid_t sp_pthread_t;
126#endif
127
128struct pam_ctxt {
129	sp_pthread_t	 pam_thread;
130	int		 pam_psock;
131	int		 pam_csock;
132	int		 pam_done;
133};
134
135static void sshpam_free_ctx(void *);
136static struct pam_ctxt *cleanup_ctxt;
137
138#ifndef UNSUPPORTED_POSIX_THREADS_HACK
139/*
140 * Simulate threads with processes.
141 */
142
143static int sshpam_thread_status = -1;
144static mysig_t sshpam_oldsig;
145
146static void
147sshpam_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 */
170static void
171pthread_exit(void *value)
172{
173	_exit(0);
174}
175
176/* ARGSUSED */
177static int
178pthread_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
203static int
204pthread_cancel(sp_pthread_t thread)
205{
206	signal(SIGCHLD, sshpam_oldsig);
207	return (kill(thread, SIGTERM));
208}
209
210/* ARGSUSED */
211static int
212pthread_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
225static pam_handle_t *sshpam_handle = NULL;
226static int sshpam_err = 0;
227static int sshpam_authenticated = 0;
228static int sshpam_session_open = 0;
229static int sshpam_cred_established = 0;
230static int sshpam_account_status = -1;
231static char **sshpam_env = NULL;
232static Authctxt *sshpam_authctxt = NULL;
233static const char *sshpam_password = NULL;
234static char badpw[] = "\b\n\r\177INCORRECT";
235
236/* Some PAM implementations don't implement this */
237#ifndef HAVE_PAM_GETENVLIST
238static char **
239pam_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
258static int
259sshpam_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
275void
276sshpam_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 */
294static void
295import_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 */
340static int
341sshpam_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		if (reply[i].resp != NULL)
416			xfree(reply[i].resp);
417	}
418	xfree(reply);
419	buffer_free(&buffer);
420	return (PAM_CONV_ERR);
421}
422
423/*
424 * Authentication thread.
425 */
426static void *
427sshpam_thread(void *ctxtp)
428{
429	struct pam_ctxt *ctxt = ctxtp;
430	Buffer buffer;
431	struct pam_conv sshpam_conv;
432	int flags = (options.permit_empty_passwd == 0 ?
433	    PAM_DISALLOW_NULL_AUTHTOK : 0);
434#ifndef UNSUPPORTED_POSIX_THREADS_HACK
435	extern char **environ;
436	char **env_from_pam;
437	u_int i;
438	const char *pam_user;
439	const char **ptr_pam_user = &pam_user;
440	char *tz = getenv("TZ");
441
442	pam_get_item(sshpam_handle, PAM_USER,
443	    (sshpam_const void **)ptr_pam_user);
444
445	environ[0] = NULL;
446	if (tz != NULL)
447		if (setenv("TZ", tz, 1) == -1)
448			error("PAM: could not set TZ environment: %s",
449			    strerror(errno));
450
451	if (sshpam_authctxt != NULL) {
452		setproctitle("%s [pam]",
453		    sshpam_authctxt->valid ? pam_user : "unknown");
454	}
455#endif
456
457	sshpam_conv.conv = sshpam_thread_conv;
458	sshpam_conv.appdata_ptr = ctxt;
459
460	if (sshpam_authctxt == NULL)
461		fatal("%s: PAM authctxt not initialized", __func__);
462
463	buffer_init(&buffer);
464	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
465	    (const void *)&sshpam_conv);
466	if (sshpam_err != PAM_SUCCESS)
467		goto auth_fail;
468	sshpam_err = pam_authenticate(sshpam_handle, flags);
469	if (sshpam_err != PAM_SUCCESS)
470		goto auth_fail;
471
472	if (compat20) {
473		if (!do_pam_account()) {
474			sshpam_err = PAM_ACCT_EXPIRED;
475			goto auth_fail;
476		}
477		if (sshpam_authctxt->force_pwchange) {
478			sshpam_err = pam_chauthtok(sshpam_handle,
479			    PAM_CHANGE_EXPIRED_AUTHTOK);
480			if (sshpam_err != PAM_SUCCESS)
481				goto auth_fail;
482			sshpam_password_change_required(0);
483		}
484	}
485
486	buffer_put_cstring(&buffer, "OK");
487
488#ifndef UNSUPPORTED_POSIX_THREADS_HACK
489	/* Export variables set by do_pam_account */
490	buffer_put_int(&buffer, sshpam_account_status);
491	buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);
492
493	/* Export any environment strings set in child */
494	for(i = 0; environ[i] != NULL; i++)
495		; /* Count */
496	buffer_put_int(&buffer, i);
497	for(i = 0; environ[i] != NULL; i++)
498		buffer_put_cstring(&buffer, environ[i]);
499
500	/* Export any environment strings set by PAM in child */
501	env_from_pam = pam_getenvlist(sshpam_handle);
502	for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
503		; /* Count */
504	buffer_put_int(&buffer, i);
505	for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
506		buffer_put_cstring(&buffer, env_from_pam[i]);
507#endif /* UNSUPPORTED_POSIX_THREADS_HACK */
508
509	/* XXX - can't do much about an error here */
510	ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
511	buffer_free(&buffer);
512	pthread_exit(NULL);
513
514 auth_fail:
515	buffer_put_cstring(&buffer,
516	    pam_strerror(sshpam_handle, sshpam_err));
517	/* XXX - can't do much about an error here */
518	if (sshpam_err == PAM_ACCT_EXPIRED)
519		ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, &buffer);
520	else
521		ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
522	buffer_free(&buffer);
523	pthread_exit(NULL);
524
525	return (NULL); /* Avoid warning for non-pthread case */
526}
527
528void
529sshpam_thread_cleanup(void)
530{
531	struct pam_ctxt *ctxt = cleanup_ctxt;
532
533	debug3("PAM: %s entering", __func__);
534	if (ctxt != NULL && ctxt->pam_thread != 0) {
535		pthread_cancel(ctxt->pam_thread);
536		pthread_join(ctxt->pam_thread, NULL);
537		close(ctxt->pam_psock);
538		close(ctxt->pam_csock);
539		memset(ctxt, 0, sizeof(*ctxt));
540		cleanup_ctxt = NULL;
541	}
542}
543
544static int
545sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
546    struct pam_response **resp, void *data)
547{
548	debug3("PAM: %s entering, %d messages", __func__, n);
549	return (PAM_CONV_ERR);
550}
551
552static struct pam_conv null_conv = { sshpam_null_conv, NULL };
553
554static int
555sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
556    struct pam_response **resp, void *data)
557{
558	struct pam_response *reply;
559	int i;
560	size_t len;
561
562	debug3("PAM: %s called with %d messages", __func__, n);
563	*resp = NULL;
564
565	if (n <= 0 || n > PAM_MAX_NUM_MSG)
566		return (PAM_CONV_ERR);
567
568	if ((reply = calloc(n, sizeof(*reply))) == NULL)
569		return (PAM_CONV_ERR);
570
571	for (i = 0; i < n; ++i) {
572		switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
573		case PAM_ERROR_MSG:
574		case PAM_TEXT_INFO:
575			len = strlen(PAM_MSG_MEMBER(msg, i, msg));
576			buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
577			buffer_append(&loginmsg, "\n", 1 );
578			reply[i].resp_retcode = PAM_SUCCESS;
579			break;
580		default:
581			goto fail;
582		}
583	}
584	*resp = reply;
585	return (PAM_SUCCESS);
586
587 fail:
588	for(i = 0; i < n; i++) {
589		if (reply[i].resp != NULL)
590			xfree(reply[i].resp);
591	}
592	xfree(reply);
593	return (PAM_CONV_ERR);
594}
595
596static struct pam_conv store_conv = { sshpam_store_conv, NULL };
597
598void
599sshpam_cleanup(void)
600{
601	if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor()))
602		return;
603	debug("PAM: cleanup");
604	pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
605	if (sshpam_session_open) {
606		debug("PAM: closing session");
607		pam_close_session(sshpam_handle, PAM_SILENT);
608		sshpam_session_open = 0;
609	}
610	if (sshpam_cred_established) {
611		debug("PAM: deleting credentials");
612		pam_setcred(sshpam_handle, PAM_DELETE_CRED);
613		sshpam_cred_established = 0;
614	}
615	sshpam_authenticated = 0;
616	pam_end(sshpam_handle, sshpam_err);
617	sshpam_handle = NULL;
618}
619
620static int
621sshpam_init(Authctxt *authctxt)
622{
623	extern char *__progname;
624	const char *pam_rhost, *pam_user, *user = authctxt->user;
625	const char **ptr_pam_user = &pam_user;
626
627	if (sshpam_handle != NULL) {
628		/* We already have a PAM context; check if the user matches */
629		sshpam_err = pam_get_item(sshpam_handle,
630		    PAM_USER, (sshpam_const void **)ptr_pam_user);
631		if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
632			return (0);
633		pam_end(sshpam_handle, sshpam_err);
634		sshpam_handle = NULL;
635	}
636	debug("PAM: initializing for \"%s\"", user);
637	sshpam_err =
638	    pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
639	sshpam_authctxt = authctxt;
640
641	if (sshpam_err != PAM_SUCCESS) {
642		pam_end(sshpam_handle, sshpam_err);
643		sshpam_handle = NULL;
644		return (-1);
645	}
646	pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
647	debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
648	sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
649	if (sshpam_err != PAM_SUCCESS) {
650		pam_end(sshpam_handle, sshpam_err);
651		sshpam_handle = NULL;
652		return (-1);
653	}
654#ifdef PAM_TTY_KLUDGE
655	/*
656	 * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
657	 * sshd doesn't set the tty until too late in the auth process and
658	 * may not even set one (for tty-less connections)
659	 */
660	debug("PAM: setting PAM_TTY to \"ssh\"");
661	sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
662	if (sshpam_err != PAM_SUCCESS) {
663		pam_end(sshpam_handle, sshpam_err);
664		sshpam_handle = NULL;
665		return (-1);
666	}
667#endif
668	return (0);
669}
670
671static void *
672sshpam_init_ctx(Authctxt *authctxt)
673{
674	struct pam_ctxt *ctxt;
675	int socks[2];
676
677	debug3("PAM: %s entering", __func__);
678	/*
679	 * Refuse to start if we don't have PAM enabled or do_pam_account
680	 * has previously failed.
681	 */
682	if (!options.use_pam || sshpam_account_status == 0)
683		return NULL;
684
685	/* Initialize PAM */
686	if (sshpam_init(authctxt) == -1) {
687		error("PAM: initialization failed");
688		return (NULL);
689	}
690
691	ctxt = xcalloc(1, sizeof *ctxt);
692
693	/* Start the authentication thread */
694	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
695		error("PAM: failed create sockets: %s", strerror(errno));
696		xfree(ctxt);
697		return (NULL);
698	}
699	ctxt->pam_psock = socks[0];
700	ctxt->pam_csock = socks[1];
701	if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
702		error("PAM: failed to start authentication thread: %s",
703		    strerror(errno));
704		close(socks[0]);
705		close(socks[1]);
706		xfree(ctxt);
707		return (NULL);
708	}
709	cleanup_ctxt = ctxt;
710	return (ctxt);
711}
712
713static int
714sshpam_query(void *ctx, char **name, char **info,
715    u_int *num, char ***prompts, u_int **echo_on)
716{
717	Buffer buffer;
718	struct pam_ctxt *ctxt = ctx;
719	size_t plen;
720	u_char type;
721	char *msg;
722	size_t len, mlen;
723
724	debug3("PAM: %s entering", __func__);
725	buffer_init(&buffer);
726	*name = xstrdup("");
727	*info = xstrdup("");
728	*prompts = xmalloc(sizeof(char *));
729	**prompts = NULL;
730	plen = 0;
731	*echo_on = xmalloc(sizeof(u_int));
732	while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
733		type = buffer_get_char(&buffer);
734		msg = buffer_get_string(&buffer, NULL);
735		mlen = strlen(msg);
736		switch (type) {
737		case PAM_PROMPT_ECHO_ON:
738		case PAM_PROMPT_ECHO_OFF:
739			*num = 1;
740			len = plen + mlen + 1;
741			**prompts = xrealloc(**prompts, 1, len);
742			strlcpy(**prompts + plen, msg, len - plen);
743			plen += mlen;
744			**echo_on = (type == PAM_PROMPT_ECHO_ON);
745			xfree(msg);
746			return (0);
747		case PAM_ERROR_MSG:
748		case PAM_TEXT_INFO:
749			/* accumulate messages */
750			len = plen + mlen + 2;
751			**prompts = xrealloc(**prompts, 1, len);
752			strlcpy(**prompts + plen, msg, len - plen);
753			plen += mlen;
754			strlcat(**prompts + plen, "\n", len - plen);
755			plen++;
756			xfree(msg);
757			break;
758		case PAM_ACCT_EXPIRED:
759			sshpam_account_status = 0;
760			/* FALLTHROUGH */
761		case PAM_AUTH_ERR:
762			debug3("PAM: %s", pam_strerror(sshpam_handle, type));
763			if (**prompts != NULL && strlen(**prompts) != 0) {
764				*info = **prompts;
765				**prompts = NULL;
766				*num = 0;
767				**echo_on = 0;
768				ctxt->pam_done = -1;
769				xfree(msg);
770				return 0;
771			}
772			/* FALLTHROUGH */
773		case PAM_SUCCESS:
774			if (**prompts != NULL) {
775				/* drain any accumulated messages */
776				debug("PAM: %s", **prompts);
777				buffer_append(&loginmsg, **prompts,
778				    strlen(**prompts));
779				xfree(**prompts);
780				**prompts = NULL;
781			}
782			if (type == PAM_SUCCESS) {
783				if (!sshpam_authctxt->valid ||
784				    (sshpam_authctxt->pw->pw_uid == 0 &&
785				    options.permit_root_login != PERMIT_YES))
786					fatal("Internal error: PAM auth "
787					    "succeeded when it should have "
788					    "failed");
789				import_environments(&buffer);
790				*num = 0;
791				**echo_on = 0;
792				ctxt->pam_done = 1;
793				xfree(msg);
794				return (0);
795			}
796			error("PAM: %s for %s%.100s from %.100s", msg,
797			    sshpam_authctxt->valid ? "" : "illegal user ",
798			    sshpam_authctxt->user,
799			    get_remote_name_or_ip(utmp_len, options.use_dns));
800			/* FALLTHROUGH */
801		default:
802			*num = 0;
803			**echo_on = 0;
804			xfree(msg);
805			ctxt->pam_done = -1;
806			return (-1);
807		}
808	}
809	return (-1);
810}
811
812/* XXX - see also comment in auth-chall.c:verify_response */
813static int
814sshpam_respond(void *ctx, u_int num, char **resp)
815{
816	Buffer buffer;
817	struct pam_ctxt *ctxt = ctx;
818
819	debug2("PAM: %s entering, %u responses", __func__, num);
820	switch (ctxt->pam_done) {
821	case 1:
822		sshpam_authenticated = 1;
823		return (0);
824	case 0:
825		break;
826	default:
827		return (-1);
828	}
829	if (num != 1) {
830		error("PAM: expected one response, got %u", num);
831		return (-1);
832	}
833	buffer_init(&buffer);
834	if (sshpam_authctxt->valid &&
835	    (sshpam_authctxt->pw->pw_uid != 0 ||
836	    options.permit_root_login == PERMIT_YES))
837		buffer_put_cstring(&buffer, *resp);
838	else
839		buffer_put_cstring(&buffer, badpw);
840	if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
841		buffer_free(&buffer);
842		return (-1);
843	}
844	buffer_free(&buffer);
845	return (1);
846}
847
848static void
849sshpam_free_ctx(void *ctxtp)
850{
851	struct pam_ctxt *ctxt = ctxtp;
852
853	debug3("PAM: %s entering", __func__);
854	sshpam_thread_cleanup();
855	xfree(ctxt);
856	/*
857	 * We don't call sshpam_cleanup() here because we may need the PAM
858	 * handle at a later stage, e.g. when setting up a session.  It's
859	 * still on the cleanup list, so pam_end() *will* be called before
860	 * the server process terminates.
861	 */
862}
863
864KbdintDevice sshpam_device = {
865	"pam",
866	sshpam_init_ctx,
867	sshpam_query,
868	sshpam_respond,
869	sshpam_free_ctx
870};
871
872KbdintDevice mm_sshpam_device = {
873	"pam",
874	mm_sshpam_init_ctx,
875	mm_sshpam_query,
876	mm_sshpam_respond,
877	mm_sshpam_free_ctx
878};
879
880/*
881 * This replaces auth-pam.c
882 */
883void
884start_pam(Authctxt *authctxt)
885{
886	if (!options.use_pam)
887		fatal("PAM: initialisation requested when UsePAM=no");
888
889	if (sshpam_init(authctxt) == -1)
890		fatal("PAM: initialisation failed");
891}
892
893void
894finish_pam(void)
895{
896	sshpam_cleanup();
897}
898
899u_int
900do_pam_account(void)
901{
902	debug("%s: called", __func__);
903	if (sshpam_account_status != -1)
904		return (sshpam_account_status);
905
906	sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
907	debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
908	    pam_strerror(sshpam_handle, sshpam_err));
909
910	if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
911		sshpam_account_status = 0;
912		return (sshpam_account_status);
913	}
914
915	if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
916		sshpam_password_change_required(1);
917
918	sshpam_account_status = 1;
919	return (sshpam_account_status);
920}
921
922void
923do_pam_set_tty(const char *tty)
924{
925	if (tty != NULL) {
926		debug("PAM: setting PAM_TTY to \"%s\"", tty);
927		sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
928		if (sshpam_err != PAM_SUCCESS)
929			fatal("PAM: failed to set PAM_TTY: %s",
930			    pam_strerror(sshpam_handle, sshpam_err));
931	}
932}
933
934void
935do_pam_setcred(int init)
936{
937	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
938	    (const void *)&store_conv);
939	if (sshpam_err != PAM_SUCCESS)
940		fatal("PAM: failed to set PAM_CONV: %s",
941		    pam_strerror(sshpam_handle, sshpam_err));
942	if (init) {
943		debug("PAM: establishing credentials");
944		sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
945	} else {
946		debug("PAM: reinitializing credentials");
947		sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
948	}
949	if (sshpam_err == PAM_SUCCESS) {
950		sshpam_cred_established = 1;
951		return;
952	}
953	if (sshpam_authenticated)
954		fatal("PAM: pam_setcred(): %s",
955		    pam_strerror(sshpam_handle, sshpam_err));
956	else
957		debug("PAM: pam_setcred(): %s",
958		    pam_strerror(sshpam_handle, sshpam_err));
959}
960
961static int
962sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
963    struct pam_response **resp, void *data)
964{
965	char input[PAM_MAX_MSG_SIZE];
966	struct pam_response *reply;
967	int i;
968
969	debug3("PAM: %s called with %d messages", __func__, n);
970
971	*resp = NULL;
972
973	if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
974		return (PAM_CONV_ERR);
975
976	if ((reply = calloc(n, sizeof(*reply))) == NULL)
977		return (PAM_CONV_ERR);
978
979	for (i = 0; i < n; ++i) {
980		switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
981		case PAM_PROMPT_ECHO_OFF:
982			reply[i].resp =
983			    read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
984			    RP_ALLOW_STDIN);
985			reply[i].resp_retcode = PAM_SUCCESS;
986			break;
987		case PAM_PROMPT_ECHO_ON:
988			fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
989			if (fgets(input, sizeof input, stdin) == NULL)
990				input[0] = '\0';
991			if ((reply[i].resp = strdup(input)) == NULL)
992				goto fail;
993			reply[i].resp_retcode = PAM_SUCCESS;
994			break;
995		case PAM_ERROR_MSG:
996		case PAM_TEXT_INFO:
997			fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
998			reply[i].resp_retcode = PAM_SUCCESS;
999			break;
1000		default:
1001			goto fail;
1002		}
1003	}
1004	*resp = reply;
1005	return (PAM_SUCCESS);
1006
1007 fail:
1008	for(i = 0; i < n; i++) {
1009		if (reply[i].resp != NULL)
1010			xfree(reply[i].resp);
1011	}
1012	xfree(reply);
1013	return (PAM_CONV_ERR);
1014}
1015
1016static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
1017
1018/*
1019 * XXX this should be done in the authentication phase, but ssh1 doesn't
1020 * support that
1021 */
1022void
1023do_pam_chauthtok(void)
1024{
1025	if (use_privsep)
1026		fatal("Password expired (unable to change with privsep)");
1027	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1028	    (const void *)&tty_conv);
1029	if (sshpam_err != PAM_SUCCESS)
1030		fatal("PAM: failed to set PAM_CONV: %s",
1031		    pam_strerror(sshpam_handle, sshpam_err));
1032	debug("PAM: changing password");
1033	sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
1034	if (sshpam_err != PAM_SUCCESS)
1035		fatal("PAM: pam_chauthtok(): %s",
1036		    pam_strerror(sshpam_handle, sshpam_err));
1037}
1038
1039void
1040do_pam_session(void)
1041{
1042	debug3("PAM: opening session");
1043	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1044	    (const void *)&store_conv);
1045	if (sshpam_err != PAM_SUCCESS)
1046		fatal("PAM: failed to set PAM_CONV: %s",
1047		    pam_strerror(sshpam_handle, sshpam_err));
1048	sshpam_err = pam_open_session(sshpam_handle, 0);
1049	if (sshpam_err == PAM_SUCCESS)
1050		sshpam_session_open = 1;
1051	else {
1052		sshpam_session_open = 0;
1053		disable_forwarding();
1054		error("PAM: pam_open_session(): %s",
1055		    pam_strerror(sshpam_handle, sshpam_err));
1056	}
1057
1058}
1059
1060int
1061is_pam_session_open(void)
1062{
1063	return sshpam_session_open;
1064}
1065
1066/*
1067 * Set a PAM environment string. We need to do this so that the session
1068 * modules can handle things like Kerberos/GSI credentials that appear
1069 * during the ssh authentication process.
1070 */
1071int
1072do_pam_putenv(char *name, char *value)
1073{
1074	int ret = 1;
1075#ifdef HAVE_PAM_PUTENV
1076	char *compound;
1077	size_t len;
1078
1079	len = strlen(name) + strlen(value) + 2;
1080	compound = xmalloc(len);
1081
1082	snprintf(compound, len, "%s=%s", name, value);
1083	ret = pam_putenv(sshpam_handle, compound);
1084	xfree(compound);
1085#endif
1086
1087	return (ret);
1088}
1089
1090char **
1091fetch_pam_child_environment(void)
1092{
1093	return sshpam_env;
1094}
1095
1096char **
1097fetch_pam_environment(void)
1098{
1099	return (pam_getenvlist(sshpam_handle));
1100}
1101
1102void
1103free_pam_environment(char **env)
1104{
1105	char **envp;
1106
1107	if (env == NULL)
1108		return;
1109
1110	for (envp = env; *envp; envp++)
1111		xfree(*envp);
1112	xfree(env);
1113}
1114
1115/*
1116 * "Blind" conversation function for password authentication.  Assumes that
1117 * echo-off prompts are for the password and stores messages for later
1118 * display.
1119 */
1120static int
1121sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1122    struct pam_response **resp, void *data)
1123{
1124	struct pam_response *reply;
1125	int i;
1126	size_t len;
1127
1128	debug3("PAM: %s called with %d messages", __func__, n);
1129
1130	*resp = NULL;
1131
1132	if (n <= 0 || n > PAM_MAX_NUM_MSG)
1133		return (PAM_CONV_ERR);
1134
1135	if ((reply = calloc(n, sizeof(*reply))) == NULL)
1136		return (PAM_CONV_ERR);
1137
1138	for (i = 0; i < n; ++i) {
1139		switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1140		case PAM_PROMPT_ECHO_OFF:
1141			if (sshpam_password == NULL)
1142				goto fail;
1143			if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1144				goto fail;
1145			reply[i].resp_retcode = PAM_SUCCESS;
1146			break;
1147		case PAM_ERROR_MSG:
1148		case PAM_TEXT_INFO:
1149			len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1150			if (len > 0) {
1151				buffer_append(&loginmsg,
1152				    PAM_MSG_MEMBER(msg, i, msg), len);
1153				buffer_append(&loginmsg, "\n", 1);
1154			}
1155			if ((reply[i].resp = strdup("")) == NULL)
1156				goto fail;
1157			reply[i].resp_retcode = PAM_SUCCESS;
1158			break;
1159		default:
1160			goto fail;
1161		}
1162	}
1163	*resp = reply;
1164	return (PAM_SUCCESS);
1165
1166 fail:
1167	for(i = 0; i < n; i++) {
1168		if (reply[i].resp != NULL)
1169			xfree(reply[i].resp);
1170	}
1171	xfree(reply);
1172	return (PAM_CONV_ERR);
1173}
1174
1175static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1176
1177/*
1178 * Attempt password authentication via PAM
1179 */
1180int
1181sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1182{
1183	int flags = (options.permit_empty_passwd == 0 ?
1184	    PAM_DISALLOW_NULL_AUTHTOK : 0);
1185
1186	if (!options.use_pam || sshpam_handle == NULL)
1187		fatal("PAM: %s called when PAM disabled or failed to "
1188		    "initialise.", __func__);
1189
1190	sshpam_password = password;
1191	sshpam_authctxt = authctxt;
1192
1193	/*
1194	 * If the user logging in is invalid, or is root but is not permitted
1195	 * by PermitRootLogin, use an invalid password to prevent leaking
1196	 * information via timing (eg if the PAM config has a delay on fail).
1197	 */
1198	if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1199	    options.permit_root_login != PERMIT_YES))
1200		sshpam_password = badpw;
1201
1202	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1203	    (const void *)&passwd_conv);
1204	if (sshpam_err != PAM_SUCCESS)
1205		fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1206		    pam_strerror(sshpam_handle, sshpam_err));
1207
1208	sshpam_err = pam_authenticate(sshpam_handle, flags);
1209	sshpam_password = NULL;
1210	if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1211		debug("PAM: password authentication accepted for %.100s",
1212		    authctxt->user);
1213		return 1;
1214	} else {
1215		debug("PAM: password authentication failed for %.100s: %s",
1216		    authctxt->valid ? authctxt->user : "an illegal user",
1217		    pam_strerror(sshpam_handle, sshpam_err));
1218		return 0;
1219	}
1220}
1221#endif /* USE_PAM */
1222