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 <stdlib.h>
60 #include <string.h>
61 #include <unistd.h>
62
63 #ifdef USE_PAM
64 #if defined(HAVE_SECURITY_PAM_APPL_H)
65 #include <security/pam_appl.h>
66 #elif defined (HAVE_PAM_PAM_APPL_H)
67 #include <pam/pam_appl.h>
68 #endif
69
70 #if !defined(SSHD_PAM_SERVICE)
71 extern char *__progname;
72 # define SSHD_PAM_SERVICE __progname
73 #endif
74
75 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */
76 #ifdef PAM_SUN_CODEBASE
77 # define sshpam_const /* Solaris, HP-UX, SunOS */
78 #else
79 # define sshpam_const const /* LinuxPAM, OpenPAM, AIX */
80 #endif
81
82 /* Ambiguity in spec: is it an array of pointers or a pointer to an array? */
83 #ifdef PAM_SUN_CODEBASE
84 # define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member)
85 #else
86 # define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member)
87 #endif
88
89 #include "xmalloc.h"
90 #include "sshbuf.h"
91 #include "ssherr.h"
92 #include "hostfile.h"
93 #include "auth.h"
94 #include "auth-pam.h"
95 #include "canohost.h"
96 #include "log.h"
97 #include "msg.h"
98 #include "packet.h"
99 #include "misc.h"
100 #include "servconf.h"
101 #include "ssh2.h"
102 #include "auth-options.h"
103 #include "misc.h"
104 #ifdef GSSAPI
105 #include "ssh-gss.h"
106 #endif
107 #include "monitor_wrap.h"
108
109 extern ServerOptions options;
110 extern struct sshbuf *loginmsg;
111 extern u_int utmp_len;
112
113 /* so we don't silently change behaviour */
114 #ifdef USE_POSIX_THREADS
115 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
116 #endif
117
118 /*
119 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
120 * and generally a bad idea. Use at own risk and do not expect support if
121 * this breaks.
122 */
123 #ifdef UNSUPPORTED_POSIX_THREADS_HACK
124 #include <pthread.h>
125 /*
126 * Avoid namespace clash when *not* using pthreads for systems *with*
127 * pthreads, which unconditionally define pthread_t via sys/types.h
128 * (e.g. Linux)
129 */
130 typedef pthread_t sp_pthread_t;
131 #else
132 typedef pid_t sp_pthread_t;
133 #define pthread_exit fake_pthread_exit
134 #define pthread_create fake_pthread_create
135 #define pthread_cancel fake_pthread_cancel
136 #define pthread_join fake_pthread_join
137 #endif
138
139 struct pam_ctxt {
140 sp_pthread_t pam_thread;
141 int pam_psock;
142 int pam_csock;
143 int pam_done;
144 };
145
146 static void sshpam_free_ctx(void *);
147 static struct pam_ctxt *cleanup_ctxt;
148
149 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
150 /*
151 * Simulate threads with processes.
152 */
153
154 static int sshpam_thread_status = -1;
155 static sshsig_t sshpam_oldsig;
156
157 static void
sshpam_sigchld_handler(int sig)158 sshpam_sigchld_handler(int sig)
159 {
160 ssh_signal(SIGCHLD, SIG_DFL);
161 if (cleanup_ctxt == NULL)
162 return; /* handler called after PAM cleanup, shouldn't happen */
163 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
164 <= 0) {
165 /* PAM thread has not exitted, privsep slave must have */
166 kill(cleanup_ctxt->pam_thread, SIGTERM);
167 while (waitpid(cleanup_ctxt->pam_thread,
168 &sshpam_thread_status, 0) == -1) {
169 if (errno == EINTR)
170 continue;
171 return;
172 }
173 }
174 if (WIFSIGNALED(sshpam_thread_status) &&
175 WTERMSIG(sshpam_thread_status) == SIGTERM)
176 return; /* terminated by pthread_cancel */
177 if (!WIFEXITED(sshpam_thread_status))
178 sigdie("PAM: authentication thread exited unexpectedly");
179 if (WEXITSTATUS(sshpam_thread_status) != 0)
180 sigdie("PAM: authentication thread exited uncleanly");
181 }
182
183 /* ARGSUSED */
184 static void
pthread_exit(void * value)185 pthread_exit(void *value)
186 {
187 _exit(0);
188 }
189
190 /* ARGSUSED */
191 static int
pthread_create(sp_pthread_t * thread,const void * attr,void * (* thread_start)(void *),void * arg)192 pthread_create(sp_pthread_t *thread, const void *attr,
193 void *(*thread_start)(void *), void *arg)
194 {
195 pid_t pid;
196 struct pam_ctxt *ctx = arg;
197
198 sshpam_thread_status = -1;
199 switch ((pid = fork())) {
200 case -1:
201 error("fork(): %s", strerror(errno));
202 return errno;
203 case 0:
204 close(ctx->pam_psock);
205 ctx->pam_psock = -1;
206 thread_start(arg);
207 _exit(1);
208 default:
209 *thread = pid;
210 close(ctx->pam_csock);
211 ctx->pam_csock = -1;
212 sshpam_oldsig = ssh_signal(SIGCHLD, sshpam_sigchld_handler);
213 return (0);
214 }
215 }
216
217 static int
pthread_cancel(sp_pthread_t thread)218 pthread_cancel(sp_pthread_t thread)
219 {
220 ssh_signal(SIGCHLD, sshpam_oldsig);
221 return (kill(thread, SIGTERM));
222 }
223
224 /* ARGSUSED */
225 static int
pthread_join(sp_pthread_t thread,void ** value)226 pthread_join(sp_pthread_t thread, void **value)
227 {
228 int status;
229
230 if (sshpam_thread_status != -1)
231 return (sshpam_thread_status);
232 ssh_signal(SIGCHLD, sshpam_oldsig);
233 while (waitpid(thread, &status, 0) == -1) {
234 if (errno == EINTR)
235 continue;
236 fatal("%s: waitpid: %s", __func__, strerror(errno));
237 }
238 return (status);
239 }
240 #endif
241
242
243 static pam_handle_t *sshpam_handle = NULL;
244 static int sshpam_err = 0;
245 static int sshpam_authenticated = 0;
246 static int sshpam_session_open = 0;
247 static int sshpam_cred_established = 0;
248 static int sshpam_account_status = -1;
249 static int sshpam_maxtries_reached = 0;
250 static char **sshpam_env = NULL;
251 static Authctxt *sshpam_authctxt = NULL;
252 static const char *sshpam_password = NULL;
253 static char *sshpam_rhost = NULL;
254 static char *sshpam_laddr = NULL;
255 static char *sshpam_conninfo = NULL;
256
257 /* Some PAM implementations don't implement this */
258 #ifndef HAVE_PAM_GETENVLIST
259 static char **
pam_getenvlist(pam_handle_t * pamh)260 pam_getenvlist(pam_handle_t *pamh)
261 {
262 /*
263 * XXX - If necessary, we can still support environment passing
264 * for platforms without pam_getenvlist by searching for known
265 * env vars (e.g. KRB5CCNAME) from the PAM environment.
266 */
267 return NULL;
268 }
269 #endif
270
271 #ifndef HAVE_PAM_PUTENV
272 static int
pam_putenv(pam_handle_t * pamh,const char * name_value)273 pam_putenv(pam_handle_t *pamh, const char *name_value)
274 {
275 return PAM_SUCCESS;
276 }
277 #endif /* HAVE_PAM_PUTENV */
278
279 /*
280 * Some platforms, notably Solaris, do not enforce password complexity
281 * rules during pam_chauthtok() if the real uid of the calling process
282 * is 0, on the assumption that it's being called by "passwd" run by root.
283 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
284 * the right thing.
285 */
286 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
287 static int
sshpam_chauthtok_ruid(pam_handle_t * pamh,int flags)288 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
289 {
290 int result;
291
292 if (sshpam_authctxt == NULL)
293 fatal("PAM: sshpam_authctxt not initialized");
294 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
295 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
296 result = pam_chauthtok(pamh, flags);
297 if (setreuid(0, -1) == -1)
298 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
299 return result;
300 }
301 # define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b)))
302 #endif
303
304 static void
sshpam_password_change_required(int reqd)305 sshpam_password_change_required(int reqd)
306 {
307 extern struct sshauthopt *auth_opts;
308 static int saved_port, saved_agent, saved_x11;
309
310 debug3("%s %d", __func__, reqd);
311 if (sshpam_authctxt == NULL)
312 fatal("%s: PAM authctxt not initialized", __func__);
313 sshpam_authctxt->force_pwchange = reqd;
314 if (reqd) {
315 saved_port = auth_opts->permit_port_forwarding_flag;
316 saved_agent = auth_opts->permit_agent_forwarding_flag;
317 saved_x11 = auth_opts->permit_x11_forwarding_flag;
318 auth_opts->permit_port_forwarding_flag = 0;
319 auth_opts->permit_agent_forwarding_flag = 0;
320 auth_opts->permit_x11_forwarding_flag = 0;
321 } else {
322 if (saved_port)
323 auth_opts->permit_port_forwarding_flag = saved_port;
324 if (saved_agent)
325 auth_opts->permit_agent_forwarding_flag = saved_agent;
326 if (saved_x11)
327 auth_opts->permit_x11_forwarding_flag = saved_x11;
328 }
329 }
330
331 /* Import regular and PAM environment from subprocess */
332 static void
import_environments(struct sshbuf * b)333 import_environments(struct sshbuf *b)
334 {
335 char *env;
336 u_int n, i, num_env;
337 int r;
338
339 debug3("PAM: %s entering", __func__);
340
341 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
342 /* Import variables set by do_pam_account */
343 if ((r = sshbuf_get_u32(b, &n)) != 0)
344 fatal("%s: buffer error: %s", __func__, ssh_err(r));
345 if (n > INT_MAX)
346 fatal("%s: invalid PAM account status %u", __func__, n);
347 sshpam_account_status = (int)n;
348 if ((r = sshbuf_get_u32(b, &n)) != 0)
349 fatal("%s: buffer error: %s", __func__, ssh_err(r));
350 sshpam_password_change_required(n != 0);
351
352 /* Import environment from subprocess */
353 if ((r = sshbuf_get_u32(b, &num_env)) != 0)
354 fatal("%s: buffer error: %s", __func__, ssh_err(r));
355 if (num_env > 1024)
356 fatal("%s: received %u environment variables, expected <= 1024",
357 __func__, num_env);
358 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env));
359 debug3("PAM: num env strings %d", num_env);
360 for(i = 0; i < num_env; i++) {
361 if ((r = sshbuf_get_cstring(b, &(sshpam_env[i]), NULL)) != 0)
362 fatal("%s: buffer error: %s", __func__, ssh_err(r));
363 }
364 sshpam_env[num_env] = NULL;
365
366 /* Import PAM environment from subprocess */
367 if ((r = sshbuf_get_u32(b, &num_env)) != 0)
368 fatal("%s: buffer error: %s", __func__, ssh_err(r));
369 debug("PAM: num PAM env strings %d", num_env);
370 for (i = 0; i < num_env; i++) {
371 if ((r = sshbuf_get_cstring(b, &env, NULL)) != 0)
372 fatal("%s: buffer error: %s", __func__, ssh_err(r));
373 /* Errors are not fatal here */
374 if ((r = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
375 error("PAM: pam_putenv: %s",
376 pam_strerror(sshpam_handle, r));
377 }
378 /* XXX leak env? */
379 }
380 #endif
381 }
382
383 /*
384 * Conversation function for authentication thread.
385 */
386 static int
sshpam_thread_conv(int n,sshpam_const struct pam_message ** msg,struct pam_response ** resp,void * data)387 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
388 struct pam_response **resp, void *data)
389 {
390 struct sshbuf *buffer;
391 struct pam_ctxt *ctxt;
392 struct pam_response *reply;
393 int r, i;
394 u_char status;
395
396 debug3("PAM: %s entering, %d messages", __func__, n);
397 *resp = NULL;
398
399 if (data == NULL) {
400 error("PAM: conversation function passed a null context");
401 return (PAM_CONV_ERR);
402 }
403 ctxt = data;
404 if (n <= 0 || n > PAM_MAX_NUM_MSG)
405 return (PAM_CONV_ERR);
406
407 if ((reply = calloc(n, sizeof(*reply))) == NULL)
408 return PAM_CONV_ERR;
409 if ((buffer = sshbuf_new()) == NULL) {
410 free(reply);
411 return PAM_CONV_ERR;
412 }
413
414 for (i = 0; i < n; ++i) {
415 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
416 case PAM_PROMPT_ECHO_OFF:
417 case PAM_PROMPT_ECHO_ON:
418 if ((r = sshbuf_put_cstring(buffer,
419 PAM_MSG_MEMBER(msg, i, msg))) != 0)
420 fatal("%s: buffer error: %s",
421 __func__, ssh_err(r));
422 if (ssh_msg_send(ctxt->pam_csock,
423 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1)
424 goto fail;
425
426 if (ssh_msg_recv(ctxt->pam_csock, buffer) == -1)
427 goto fail;
428 if ((r = sshbuf_get_u8(buffer, &status)) != 0)
429 fatal("%s: buffer error: %s",
430 __func__, ssh_err(r));
431 if (status != PAM_AUTHTOK)
432 goto fail;
433 if ((r = sshbuf_get_cstring(buffer,
434 &reply[i].resp, NULL)) != 0)
435 fatal("%s: buffer error: %s",
436 __func__, ssh_err(r));
437 break;
438 case PAM_ERROR_MSG:
439 case PAM_TEXT_INFO:
440 if ((r = sshbuf_put_cstring(buffer,
441 PAM_MSG_MEMBER(msg, i, msg))) != 0)
442 fatal("%s: buffer error: %s",
443 __func__, ssh_err(r));
444 if (ssh_msg_send(ctxt->pam_csock,
445 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1)
446 goto fail;
447 break;
448 default:
449 goto fail;
450 }
451 sshbuf_reset(buffer);
452 }
453 sshbuf_free(buffer);
454 *resp = reply;
455 return (PAM_SUCCESS);
456
457 fail:
458 for(i = 0; i < n; i++) {
459 free(reply[i].resp);
460 }
461 free(reply);
462 sshbuf_free(buffer);
463 return (PAM_CONV_ERR);
464 }
465
466 /*
467 * Authentication thread.
468 */
469 static void *
sshpam_thread(void * ctxtp)470 sshpam_thread(void *ctxtp)
471 {
472 struct pam_ctxt *ctxt = ctxtp;
473 struct sshbuf *buffer = NULL;
474 struct pam_conv sshpam_conv;
475 int r, flags = (options.permit_empty_passwd == 0 ?
476 PAM_DISALLOW_NULL_AUTHTOK : 0);
477 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
478 extern char **environ;
479 char **env_from_pam;
480 u_int i;
481 const char *pam_user;
482 const char **ptr_pam_user = &pam_user;
483 char *tz = getenv("TZ");
484
485 sshpam_err = pam_get_item(sshpam_handle, PAM_USER,
486 (sshpam_const void **)ptr_pam_user);
487 if (sshpam_err != PAM_SUCCESS)
488 goto auth_fail;
489
490 environ[0] = NULL;
491 if (tz != NULL)
492 if (setenv("TZ", tz, 1) == -1)
493 error("PAM: could not set TZ environment: %s",
494 strerror(errno));
495
496 if (sshpam_authctxt != NULL) {
497 setproctitle("%s [pam]",
498 sshpam_authctxt->valid ? pam_user : "unknown");
499 }
500 #endif
501
502 sshpam_conv.conv = sshpam_thread_conv;
503 sshpam_conv.appdata_ptr = ctxt;
504
505 if (sshpam_authctxt == NULL)
506 fatal("%s: PAM authctxt not initialized", __func__);
507
508 if ((buffer = sshbuf_new()) == NULL)
509 fatal("%s: sshbuf_new failed", __func__);
510
511 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
512 (const void *)&sshpam_conv);
513 if (sshpam_err != PAM_SUCCESS)
514 goto auth_fail;
515 sshpam_err = pam_authenticate(sshpam_handle, flags);
516 if (sshpam_err == PAM_MAXTRIES)
517 sshpam_set_maxtries_reached(1);
518 if (sshpam_err != PAM_SUCCESS)
519 goto auth_fail;
520
521 if (!do_pam_account()) {
522 sshpam_err = PAM_ACCT_EXPIRED;
523 goto auth_fail;
524 }
525 if (sshpam_authctxt->force_pwchange) {
526 sshpam_err = pam_chauthtok(sshpam_handle,
527 PAM_CHANGE_EXPIRED_AUTHTOK);
528 if (sshpam_err != PAM_SUCCESS)
529 goto auth_fail;
530 sshpam_password_change_required(0);
531 }
532
533 if ((r = sshbuf_put_cstring(buffer, "OK")) != 0)
534 fatal("%s: buffer error: %s", __func__, ssh_err(r));
535
536 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
537 /* Export variables set by do_pam_account */
538 if ((r = sshbuf_put_u32(buffer, sshpam_account_status)) != 0 ||
539 (r = sshbuf_put_u32(buffer, sshpam_authctxt->force_pwchange)) != 0)
540 fatal("%s: buffer error: %s", __func__, ssh_err(r));
541
542 /* Export any environment strings set in child */
543 for (i = 0; environ[i] != NULL; i++) {
544 /* Count */
545 if (i > INT_MAX)
546 fatal("%s: too many environment strings", __func__);
547 }
548 if ((r = sshbuf_put_u32(buffer, i)) != 0)
549 fatal("%s: buffer error: %s", __func__, ssh_err(r));
550 for (i = 0; environ[i] != NULL; i++) {
551 if ((r = sshbuf_put_cstring(buffer, environ[i])) != 0)
552 fatal("%s: buffer error: %s", __func__, ssh_err(r));
553 }
554 /* Export any environment strings set by PAM in child */
555 env_from_pam = pam_getenvlist(sshpam_handle);
556 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) {
557 /* Count */
558 if (i > INT_MAX)
559 fatal("%s: too many PAM environment strings", __func__);
560 }
561 if ((r = sshbuf_put_u32(buffer, i)) != 0)
562 fatal("%s: buffer error: %s", __func__, ssh_err(r));
563 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) {
564 if ((r = sshbuf_put_cstring(buffer, env_from_pam[i])) != 0)
565 fatal("%s: buffer error: %s", __func__, ssh_err(r));
566 }
567 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */
568
569 /* XXX - can't do much about an error here */
570 ssh_msg_send(ctxt->pam_csock, sshpam_err, buffer);
571 sshbuf_free(buffer);
572 pthread_exit(NULL);
573
574 auth_fail:
575 if ((r = sshbuf_put_cstring(buffer,
576 pam_strerror(sshpam_handle, sshpam_err))) != 0)
577 fatal("%s: buffer error: %s", __func__, ssh_err(r));
578 /* XXX - can't do much about an error here */
579 if (sshpam_err == PAM_ACCT_EXPIRED)
580 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, buffer);
581 else if (sshpam_maxtries_reached)
582 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, buffer);
583 else
584 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, buffer);
585 sshbuf_free(buffer);
586 pthread_exit(NULL);
587
588 return (NULL); /* Avoid warning for non-pthread case */
589 }
590
591 void
sshpam_thread_cleanup(void)592 sshpam_thread_cleanup(void)
593 {
594 struct pam_ctxt *ctxt = cleanup_ctxt;
595
596 debug3("PAM: %s entering", __func__);
597 if (ctxt != NULL && ctxt->pam_thread != 0) {
598 pthread_cancel(ctxt->pam_thread);
599 pthread_join(ctxt->pam_thread, NULL);
600 close(ctxt->pam_psock);
601 close(ctxt->pam_csock);
602 memset(ctxt, 0, sizeof(*ctxt));
603 cleanup_ctxt = NULL;
604 }
605 }
606
607 static int
sshpam_null_conv(int n,sshpam_const struct pam_message ** msg,struct pam_response ** resp,void * data)608 sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
609 struct pam_response **resp, void *data)
610 {
611 debug3("PAM: %s entering, %d messages", __func__, n);
612 return (PAM_CONV_ERR);
613 }
614
615 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
616
617 static int
sshpam_store_conv(int n,sshpam_const struct pam_message ** msg,struct pam_response ** resp,void * data)618 sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
619 struct pam_response **resp, void *data)
620 {
621 struct pam_response *reply;
622 int r, i;
623
624 debug3("PAM: %s called with %d messages", __func__, n);
625 *resp = NULL;
626
627 if (n <= 0 || n > PAM_MAX_NUM_MSG)
628 return (PAM_CONV_ERR);
629
630 if ((reply = calloc(n, sizeof(*reply))) == NULL)
631 return (PAM_CONV_ERR);
632
633 for (i = 0; i < n; ++i) {
634 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
635 case PAM_ERROR_MSG:
636 case PAM_TEXT_INFO:
637 if ((r = sshbuf_putf(loginmsg, "%s\n",
638 PAM_MSG_MEMBER(msg, i, msg))) != 0)
639 fatal("%s: buffer error: %s",
640 __func__, ssh_err(r));
641 reply[i].resp_retcode = PAM_SUCCESS;
642 break;
643 default:
644 goto fail;
645 }
646 }
647 *resp = reply;
648 return (PAM_SUCCESS);
649
650 fail:
651 for(i = 0; i < n; i++) {
652 free(reply[i].resp);
653 }
654 free(reply);
655 return (PAM_CONV_ERR);
656 }
657
658 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
659
660 void
sshpam_cleanup(void)661 sshpam_cleanup(void)
662 {
663 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor()))
664 return;
665 debug("PAM: cleanup");
666 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
667 if (sshpam_session_open) {
668 debug("PAM: closing session");
669 pam_close_session(sshpam_handle, PAM_SILENT);
670 sshpam_session_open = 0;
671 }
672 if (sshpam_cred_established) {
673 debug("PAM: deleting credentials");
674 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
675 sshpam_cred_established = 0;
676 }
677 sshpam_authenticated = 0;
678 pam_end(sshpam_handle, sshpam_err);
679 sshpam_handle = NULL;
680 }
681
682 static int
sshpam_init(struct ssh * ssh,Authctxt * authctxt)683 sshpam_init(struct ssh *ssh, Authctxt *authctxt)
684 {
685 const char *pam_user, *user = authctxt->user;
686 const char **ptr_pam_user = &pam_user;
687
688 if (sshpam_handle == NULL) {
689 if (ssh == NULL) {
690 fatal("%s: called initially with no "
691 "packet context", __func__);
692 }
693 } if (sshpam_handle != NULL) {
694 /* We already have a PAM context; check if the user matches */
695 sshpam_err = pam_get_item(sshpam_handle,
696 PAM_USER, (sshpam_const void **)ptr_pam_user);
697 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
698 return (0);
699 pam_end(sshpam_handle, sshpam_err);
700 sshpam_handle = NULL;
701 }
702 debug("PAM: initializing for \"%s\"", user);
703 sshpam_err =
704 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
705 sshpam_authctxt = authctxt;
706
707 if (sshpam_err != PAM_SUCCESS) {
708 pam_end(sshpam_handle, sshpam_err);
709 sshpam_handle = NULL;
710 return (-1);
711 }
712
713 if (ssh != NULL && sshpam_rhost == NULL) {
714 /*
715 * We need to cache these as we don't have packet context
716 * during the kbdint flow.
717 */
718 sshpam_rhost = xstrdup(auth_get_canonical_hostname(ssh,
719 options.use_dns));
720 sshpam_laddr = get_local_ipaddr(
721 ssh_packet_get_connection_in(ssh));
722 xasprintf(&sshpam_conninfo, "SSH_CONNECTION=%.50s %d %.50s %d",
723 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
724 sshpam_laddr, ssh_local_port(ssh));
725 }
726 if (sshpam_rhost != NULL) {
727 debug("PAM: setting PAM_RHOST to \"%s\"", sshpam_rhost);
728 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST,
729 sshpam_rhost);
730 if (sshpam_err != PAM_SUCCESS) {
731 pam_end(sshpam_handle, sshpam_err);
732 sshpam_handle = NULL;
733 return (-1);
734 }
735 /* Put SSH_CONNECTION in the PAM environment too */
736 pam_putenv(sshpam_handle, sshpam_conninfo);
737 }
738
739 #ifdef PAM_TTY_KLUDGE
740 /*
741 * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
742 * sshd doesn't set the tty until too late in the auth process and
743 * may not even set one (for tty-less connections)
744 */
745 debug("PAM: setting PAM_TTY to \"ssh\"");
746 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
747 if (sshpam_err != PAM_SUCCESS) {
748 pam_end(sshpam_handle, sshpam_err);
749 sshpam_handle = NULL;
750 return (-1);
751 }
752 #endif
753 return (0);
754 }
755
756 static void
expose_authinfo(const char * caller)757 expose_authinfo(const char *caller)
758 {
759 char *auth_info;
760
761 /*
762 * Expose authentication information to PAM.
763 * The environment variable is versioned. Please increment the
764 * version suffix if the format of session_info changes.
765 */
766 if (sshpam_authctxt->session_info == NULL)
767 auth_info = xstrdup("");
768 else if ((auth_info = sshbuf_dup_string(
769 sshpam_authctxt->session_info)) == NULL)
770 fatal("%s: sshbuf_dup_string failed", __func__);
771
772 debug2("%s: auth information in SSH_AUTH_INFO_0", caller);
773 do_pam_putenv("SSH_AUTH_INFO_0", auth_info);
774 free(auth_info);
775 }
776
777 static void *
sshpam_init_ctx(Authctxt * authctxt)778 sshpam_init_ctx(Authctxt *authctxt)
779 {
780 struct pam_ctxt *ctxt;
781 int result, socks[2];
782
783 debug3("PAM: %s entering", __func__);
784 /*
785 * Refuse to start if we don't have PAM enabled or do_pam_account
786 * has previously failed.
787 */
788 if (!options.use_pam || sshpam_account_status == 0)
789 return NULL;
790
791 /* Initialize PAM */
792 if (sshpam_init(NULL, authctxt) == -1) {
793 error("PAM: initialization failed");
794 return (NULL);
795 }
796
797 expose_authinfo(__func__);
798 ctxt = xcalloc(1, sizeof *ctxt);
799
800 /* Start the authentication thread */
801 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
802 error("PAM: failed create sockets: %s", strerror(errno));
803 free(ctxt);
804 return (NULL);
805 }
806 ctxt->pam_psock = socks[0];
807 ctxt->pam_csock = socks[1];
808 result = pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt);
809 if (result != 0) {
810 error("PAM: failed to start authentication thread: %s",
811 strerror(result));
812 close(socks[0]);
813 close(socks[1]);
814 free(ctxt);
815 return (NULL);
816 }
817 cleanup_ctxt = ctxt;
818 return (ctxt);
819 }
820
821 static int
sshpam_query(void * ctx,char ** name,char ** info,u_int * num,char *** prompts,u_int ** echo_on)822 sshpam_query(void *ctx, char **name, char **info,
823 u_int *num, char ***prompts, u_int **echo_on)
824 {
825 struct sshbuf *buffer;
826 struct pam_ctxt *ctxt = ctx;
827 size_t plen;
828 u_char type;
829 char *msg;
830 size_t len, mlen;
831 int r;
832
833 debug3("PAM: %s entering", __func__);
834 if ((buffer = sshbuf_new()) == NULL)
835 fatal("%s: sshbuf_new failed", __func__);
836 *name = xstrdup("");
837 *info = xstrdup("");
838 *prompts = xmalloc(sizeof(char *));
839 **prompts = NULL;
840 plen = 0;
841 *echo_on = xmalloc(sizeof(u_int));
842 while (ssh_msg_recv(ctxt->pam_psock, buffer) == 0) {
843 if ((r = sshbuf_get_u8(buffer, &type)) != 0 ||
844 (r = sshbuf_get_cstring(buffer, &msg, &mlen)) != 0)
845 fatal("%s: buffer error: %s", __func__, ssh_err(r));
846 switch (type) {
847 case PAM_PROMPT_ECHO_ON:
848 case PAM_PROMPT_ECHO_OFF:
849 *num = 1;
850 len = plen + mlen + 1;
851 **prompts = xreallocarray(**prompts, 1, len);
852 strlcpy(**prompts + plen, msg, len - plen);
853 plen += mlen;
854 **echo_on = (type == PAM_PROMPT_ECHO_ON);
855 free(msg);
856 sshbuf_free(buffer);
857 return (0);
858 case PAM_ERROR_MSG:
859 case PAM_TEXT_INFO:
860 /* accumulate messages */
861 len = plen + mlen + 2;
862 **prompts = xreallocarray(**prompts, 1, len);
863 strlcpy(**prompts + plen, msg, len - plen);
864 plen += mlen;
865 strlcat(**prompts + plen, "\n", len - plen);
866 plen++;
867 free(msg);
868 break;
869 case PAM_ACCT_EXPIRED:
870 case PAM_MAXTRIES:
871 if (type == PAM_ACCT_EXPIRED)
872 sshpam_account_status = 0;
873 if (type == PAM_MAXTRIES)
874 sshpam_set_maxtries_reached(1);
875 /* FALLTHROUGH */
876 case PAM_AUTH_ERR:
877 debug3("PAM: %s", pam_strerror(sshpam_handle, type));
878 if (**prompts != NULL && strlen(**prompts) != 0) {
879 *info = **prompts;
880 **prompts = NULL;
881 *num = 0;
882 **echo_on = 0;
883 ctxt->pam_done = -1;
884 free(msg);
885 sshbuf_free(buffer);
886 return 0;
887 }
888 /* FALLTHROUGH */
889 case PAM_SUCCESS:
890 if (**prompts != NULL) {
891 /* drain any accumulated messages */
892 debug("PAM: %s", **prompts);
893 if ((r = sshbuf_put(loginmsg, **prompts,
894 strlen(**prompts))) != 0)
895 fatal("%s: buffer error: %s",
896 __func__, ssh_err(r));
897 free(**prompts);
898 **prompts = NULL;
899 }
900 if (type == PAM_SUCCESS) {
901 if (!sshpam_authctxt->valid ||
902 (sshpam_authctxt->pw->pw_uid == 0 &&
903 options.permit_root_login != PERMIT_YES))
904 fatal("Internal error: PAM auth "
905 "succeeded when it should have "
906 "failed");
907 import_environments(buffer);
908 *num = 0;
909 **echo_on = 0;
910 ctxt->pam_done = 1;
911 free(msg);
912 sshbuf_free(buffer);
913 return (0);
914 }
915 error("PAM: %s for %s%.100s from %.100s", msg,
916 sshpam_authctxt->valid ? "" : "illegal user ",
917 sshpam_authctxt->user, sshpam_rhost);
918 /* FALLTHROUGH */
919 default:
920 *num = 0;
921 **echo_on = 0;
922 free(msg);
923 ctxt->pam_done = -1;
924 sshbuf_free(buffer);
925 return (-1);
926 }
927 }
928 sshbuf_free(buffer);
929 return (-1);
930 }
931
932 /*
933 * Returns a junk password of identical length to that the user supplied.
934 * Used to mitigate timing attacks against crypt(3)/PAM stacks that
935 * vary processing time in proportion to password length.
936 */
937 static char *
fake_password(const char * wire_password)938 fake_password(const char *wire_password)
939 {
940 const char junk[] = "\b\n\r\177INCORRECT";
941 char *ret = NULL;
942 size_t i, l = wire_password != NULL ? strlen(wire_password) : 0;
943
944 if (l >= INT_MAX)
945 fatal("%s: password length too long: %zu", __func__, l);
946
947 ret = malloc(l + 1);
948 if (ret == NULL)
949 return NULL;
950 for (i = 0; i < l; i++)
951 ret[i] = junk[i % (sizeof(junk) - 1)];
952 ret[i] = '\0';
953 return ret;
954 }
955
956 /* XXX - see also comment in auth-chall.c:verify_response */
957 static int
sshpam_respond(void * ctx,u_int num,char ** resp)958 sshpam_respond(void *ctx, u_int num, char **resp)
959 {
960 struct sshbuf *buffer;
961 struct pam_ctxt *ctxt = ctx;
962 char *fake;
963 int r;
964
965 debug2("PAM: %s entering, %u responses", __func__, num);
966 switch (ctxt->pam_done) {
967 case 1:
968 sshpam_authenticated = 1;
969 return (0);
970 case 0:
971 break;
972 default:
973 return (-1);
974 }
975 if (num != 1) {
976 error("PAM: expected one response, got %u", num);
977 return (-1);
978 }
979 if ((buffer = sshbuf_new()) == NULL)
980 fatal("%s: sshbuf_new failed", __func__);
981 if (sshpam_authctxt->valid &&
982 (sshpam_authctxt->pw->pw_uid != 0 ||
983 options.permit_root_login == PERMIT_YES)) {
984 if ((r = sshbuf_put_cstring(buffer, *resp)) != 0)
985 fatal("%s: buffer error: %s", __func__, ssh_err(r));
986 } else {
987 fake = fake_password(*resp);
988 if ((r = sshbuf_put_cstring(buffer, fake)) != 0)
989 fatal("%s: buffer error: %s", __func__, ssh_err(r));
990 free(fake);
991 }
992 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, buffer) == -1) {
993 sshbuf_free(buffer);
994 return (-1);
995 }
996 sshbuf_free(buffer);
997 return (1);
998 }
999
1000 static void
sshpam_free_ctx(void * ctxtp)1001 sshpam_free_ctx(void *ctxtp)
1002 {
1003 struct pam_ctxt *ctxt = ctxtp;
1004
1005 debug3("PAM: %s entering", __func__);
1006 sshpam_thread_cleanup();
1007 free(ctxt);
1008 /*
1009 * We don't call sshpam_cleanup() here because we may need the PAM
1010 * handle at a later stage, e.g. when setting up a session. It's
1011 * still on the cleanup list, so pam_end() *will* be called before
1012 * the server process terminates.
1013 */
1014 }
1015
1016 KbdintDevice sshpam_device = {
1017 "pam",
1018 sshpam_init_ctx,
1019 sshpam_query,
1020 sshpam_respond,
1021 sshpam_free_ctx
1022 };
1023
1024 KbdintDevice mm_sshpam_device = {
1025 "pam",
1026 mm_sshpam_init_ctx,
1027 mm_sshpam_query,
1028 mm_sshpam_respond,
1029 mm_sshpam_free_ctx
1030 };
1031
1032 /*
1033 * This replaces auth-pam.c
1034 */
1035 void
start_pam(struct ssh * ssh)1036 start_pam(struct ssh *ssh)
1037 {
1038 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1039
1040 if (!options.use_pam)
1041 fatal("PAM: initialisation requested when UsePAM=no");
1042
1043 if (sshpam_init(ssh, authctxt) == -1)
1044 fatal("PAM: initialisation failed");
1045 }
1046
1047 void
finish_pam(void)1048 finish_pam(void)
1049 {
1050 sshpam_cleanup();
1051 }
1052
1053
1054 u_int
do_pam_account(void)1055 do_pam_account(void)
1056 {
1057 debug("%s: called", __func__);
1058 if (sshpam_account_status != -1)
1059 return (sshpam_account_status);
1060
1061 expose_authinfo(__func__);
1062
1063 sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
1064 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
1065 pam_strerror(sshpam_handle, sshpam_err));
1066
1067 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
1068 sshpam_account_status = 0;
1069 return (sshpam_account_status);
1070 }
1071
1072 if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
1073 sshpam_password_change_required(1);
1074
1075 sshpam_account_status = 1;
1076 return (sshpam_account_status);
1077 }
1078
1079 void
do_pam_setcred(int init)1080 do_pam_setcred(int init)
1081 {
1082 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1083 (const void *)&store_conv);
1084 if (sshpam_err != PAM_SUCCESS)
1085 fatal("PAM: failed to set PAM_CONV: %s",
1086 pam_strerror(sshpam_handle, sshpam_err));
1087 if (init) {
1088 debug("PAM: establishing credentials");
1089 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
1090 } else {
1091 debug("PAM: reinitializing credentials");
1092 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
1093 }
1094 if (sshpam_err == PAM_SUCCESS) {
1095 sshpam_cred_established = 1;
1096 return;
1097 }
1098 if (sshpam_authenticated)
1099 fatal("PAM: pam_setcred(): %s",
1100 pam_strerror(sshpam_handle, sshpam_err));
1101 else
1102 debug("PAM: pam_setcred(): %s",
1103 pam_strerror(sshpam_handle, sshpam_err));
1104 }
1105
1106 static int
sshpam_tty_conv(int n,sshpam_const struct pam_message ** msg,struct pam_response ** resp,void * data)1107 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
1108 struct pam_response **resp, void *data)
1109 {
1110 char input[PAM_MAX_MSG_SIZE];
1111 struct pam_response *reply;
1112 int i;
1113
1114 debug3("PAM: %s called with %d messages", __func__, n);
1115
1116 *resp = NULL;
1117
1118 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
1119 return (PAM_CONV_ERR);
1120
1121 if ((reply = calloc(n, sizeof(*reply))) == NULL)
1122 return (PAM_CONV_ERR);
1123
1124 for (i = 0; i < n; ++i) {
1125 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1126 case PAM_PROMPT_ECHO_OFF:
1127 reply[i].resp =
1128 read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
1129 RP_ALLOW_STDIN);
1130 reply[i].resp_retcode = PAM_SUCCESS;
1131 break;
1132 case PAM_PROMPT_ECHO_ON:
1133 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1134 if (fgets(input, sizeof input, stdin) == NULL)
1135 input[0] = '\0';
1136 if ((reply[i].resp = strdup(input)) == NULL)
1137 goto fail;
1138 reply[i].resp_retcode = PAM_SUCCESS;
1139 break;
1140 case PAM_ERROR_MSG:
1141 case PAM_TEXT_INFO:
1142 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1143 reply[i].resp_retcode = PAM_SUCCESS;
1144 break;
1145 default:
1146 goto fail;
1147 }
1148 }
1149 *resp = reply;
1150 return (PAM_SUCCESS);
1151
1152 fail:
1153 for(i = 0; i < n; i++) {
1154 free(reply[i].resp);
1155 }
1156 free(reply);
1157 return (PAM_CONV_ERR);
1158 }
1159
1160 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
1161
1162 /*
1163 * XXX this should be done in the authentication phase, but ssh1 doesn't
1164 * support that
1165 */
1166 void
do_pam_chauthtok(void)1167 do_pam_chauthtok(void)
1168 {
1169 if (use_privsep)
1170 fatal("Password expired (unable to change with privsep)");
1171 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1172 (const void *)&tty_conv);
1173 if (sshpam_err != PAM_SUCCESS)
1174 fatal("PAM: failed to set PAM_CONV: %s",
1175 pam_strerror(sshpam_handle, sshpam_err));
1176 debug("PAM: changing password");
1177 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
1178 if (sshpam_err != PAM_SUCCESS)
1179 fatal("PAM: pam_chauthtok(): %s",
1180 pam_strerror(sshpam_handle, sshpam_err));
1181 }
1182
1183 void
do_pam_session(struct ssh * ssh)1184 do_pam_session(struct ssh *ssh)
1185 {
1186 debug3("PAM: opening session");
1187
1188 expose_authinfo(__func__);
1189
1190 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1191 (const void *)&store_conv);
1192 if (sshpam_err != PAM_SUCCESS)
1193 fatal("PAM: failed to set PAM_CONV: %s",
1194 pam_strerror(sshpam_handle, sshpam_err));
1195 sshpam_err = pam_open_session(sshpam_handle, 0);
1196 if (sshpam_err == PAM_SUCCESS)
1197 sshpam_session_open = 1;
1198 else {
1199 sshpam_session_open = 0;
1200 auth_restrict_session(ssh);
1201 error("PAM: pam_open_session(): %s",
1202 pam_strerror(sshpam_handle, sshpam_err));
1203 }
1204
1205 }
1206
1207 int
is_pam_session_open(void)1208 is_pam_session_open(void)
1209 {
1210 return sshpam_session_open;
1211 }
1212
1213 /*
1214 * Set a PAM environment string. We need to do this so that the session
1215 * modules can handle things like Kerberos/GSI credentials that appear
1216 * during the ssh authentication process.
1217 */
1218 int
do_pam_putenv(char * name,char * value)1219 do_pam_putenv(char *name, char *value)
1220 {
1221 int ret = 1;
1222 char *compound;
1223 size_t len;
1224
1225 len = strlen(name) + strlen(value) + 2;
1226 compound = xmalloc(len);
1227
1228 snprintf(compound, len, "%s=%s", name, value);
1229 ret = pam_putenv(sshpam_handle, compound);
1230 free(compound);
1231
1232 return (ret);
1233 }
1234
1235 char **
fetch_pam_child_environment(void)1236 fetch_pam_child_environment(void)
1237 {
1238 return sshpam_env;
1239 }
1240
1241 char **
fetch_pam_environment(void)1242 fetch_pam_environment(void)
1243 {
1244 return (pam_getenvlist(sshpam_handle));
1245 }
1246
1247 void
free_pam_environment(char ** env)1248 free_pam_environment(char **env)
1249 {
1250 char **envp;
1251
1252 if (env == NULL)
1253 return;
1254
1255 for (envp = env; *envp; envp++)
1256 free(*envp);
1257 free(env);
1258 }
1259
1260 /*
1261 * "Blind" conversation function for password authentication. Assumes that
1262 * echo-off prompts are for the password and stores messages for later
1263 * display.
1264 */
1265 static int
sshpam_passwd_conv(int n,sshpam_const struct pam_message ** msg,struct pam_response ** resp,void * data)1266 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1267 struct pam_response **resp, void *data)
1268 {
1269 struct pam_response *reply;
1270 int r, i;
1271 size_t len;
1272
1273 debug3("PAM: %s called with %d messages", __func__, n);
1274
1275 *resp = NULL;
1276
1277 if (n <= 0 || n > PAM_MAX_NUM_MSG)
1278 return (PAM_CONV_ERR);
1279
1280 if ((reply = calloc(n, sizeof(*reply))) == NULL)
1281 return (PAM_CONV_ERR);
1282
1283 for (i = 0; i < n; ++i) {
1284 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1285 case PAM_PROMPT_ECHO_OFF:
1286 if (sshpam_password == NULL)
1287 goto fail;
1288 if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1289 goto fail;
1290 reply[i].resp_retcode = PAM_SUCCESS;
1291 break;
1292 case PAM_ERROR_MSG:
1293 case PAM_TEXT_INFO:
1294 len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1295 if (len > 0) {
1296 if ((r = sshbuf_putf(loginmsg, "%s\n",
1297 PAM_MSG_MEMBER(msg, i, msg))) != 0)
1298 fatal("%s: buffer error: %s",
1299 __func__, ssh_err(r));
1300 }
1301 if ((reply[i].resp = strdup("")) == NULL)
1302 goto fail;
1303 reply[i].resp_retcode = PAM_SUCCESS;
1304 break;
1305 default:
1306 goto fail;
1307 }
1308 }
1309 *resp = reply;
1310 return (PAM_SUCCESS);
1311
1312 fail:
1313 for(i = 0; i < n; i++) {
1314 free(reply[i].resp);
1315 }
1316 free(reply);
1317 return (PAM_CONV_ERR);
1318 }
1319
1320 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1321
1322 /*
1323 * Attempt password authentication via PAM
1324 */
1325 int
sshpam_auth_passwd(Authctxt * authctxt,const char * password)1326 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1327 {
1328 int flags = (options.permit_empty_passwd == 0 ?
1329 PAM_DISALLOW_NULL_AUTHTOK : 0);
1330 char *fake = NULL;
1331
1332 if (!options.use_pam || sshpam_handle == NULL)
1333 fatal("PAM: %s called when PAM disabled or failed to "
1334 "initialise.", __func__);
1335
1336 sshpam_password = password;
1337 sshpam_authctxt = authctxt;
1338
1339 /*
1340 * If the user logging in is invalid, or is root but is not permitted
1341 * by PermitRootLogin, use an invalid password to prevent leaking
1342 * information via timing (eg if the PAM config has a delay on fail).
1343 */
1344 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1345 options.permit_root_login != PERMIT_YES))
1346 sshpam_password = fake = fake_password(password);
1347
1348 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1349 (const void *)&passwd_conv);
1350 if (sshpam_err != PAM_SUCCESS)
1351 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1352 pam_strerror(sshpam_handle, sshpam_err));
1353
1354 sshpam_err = pam_authenticate(sshpam_handle, flags);
1355 sshpam_password = NULL;
1356 free(fake);
1357 if (sshpam_err == PAM_MAXTRIES)
1358 sshpam_set_maxtries_reached(1);
1359 if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1360 debug("PAM: password authentication accepted for %.100s",
1361 authctxt->user);
1362 return 1;
1363 } else {
1364 debug("PAM: password authentication failed for %.100s: %s",
1365 authctxt->valid ? authctxt->user : "an illegal user",
1366 pam_strerror(sshpam_handle, sshpam_err));
1367 return 0;
1368 }
1369 }
1370
1371 int
sshpam_get_maxtries_reached(void)1372 sshpam_get_maxtries_reached(void)
1373 {
1374 return sshpam_maxtries_reached;
1375 }
1376
1377 void
sshpam_set_maxtries_reached(int reached)1378 sshpam_set_maxtries_reached(int reached)
1379 {
1380 if (reached == 0 || sshpam_maxtries_reached)
1381 return;
1382 sshpam_maxtries_reached = 1;
1383 options.password_authentication = 0;
1384 options.kbd_interactive_authentication = 0;
1385 options.challenge_response_authentication = 0;
1386 }
1387 #endif /* USE_PAM */
1388