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 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */
71 #ifdef PAM_SUN_CODEBASE
72 # define sshpam_const /* Solaris, HP-UX, SunOS */
73 #else
74 # define sshpam_const const /* LinuxPAM, OpenPAM, AIX */
75 #endif
76
77 /* Ambiguity in spec: is it an array of pointers or a pointer to an array? */
78 #ifdef PAM_SUN_CODEBASE
79 # define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member)
80 #else
81 # define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member)
82 #endif
83
84 #include "xmalloc.h"
85 #include "sshbuf.h"
86 #include "ssherr.h"
87 #include "hostfile.h"
88 #include "auth.h"
89 #include "auth-pam.h"
90 #include "canohost.h"
91 #include "log.h"
92 #include "msg.h"
93 #include "packet.h"
94 #include "misc.h"
95 #include "servconf.h"
96 #include "ssh2.h"
97 #include "auth-options.h"
98 #include "misc.h"
99 #ifdef GSSAPI
100 #include "ssh-gss.h"
101 #endif
102 #include "monitor_wrap.h"
103 #include "srclimit.h"
104 #include "blacklist_client.h"
105
106 extern ServerOptions options;
107 extern struct sshbuf *loginmsg;
108 extern u_int utmp_len;
109
110 /* so we don't silently change behaviour */
111 #ifdef USE_POSIX_THREADS
112 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
113 #endif
114
115 /*
116 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
117 * and generally a bad idea. Use at own risk and do not expect support if
118 * this breaks.
119 */
120 #ifdef UNSUPPORTED_POSIX_THREADS_HACK
121 #include <pthread.h>
122 /*
123 * Avoid namespace clash when *not* using pthreads for systems *with*
124 * pthreads, which unconditionally define pthread_t via sys/types.h
125 * (e.g. Linux)
126 */
127 typedef pthread_t sp_pthread_t;
128 #else
129 typedef pid_t sp_pthread_t;
130 #define pthread_exit fake_pthread_exit
131 #define pthread_create fake_pthread_create
132 #define pthread_cancel fake_pthread_cancel
133 #define pthread_join fake_pthread_join
134 #endif
135
136 struct pam_ctxt {
137 sp_pthread_t pam_thread;
138 int pam_psock;
139 int pam_csock;
140 int pam_done;
141 };
142
143 static void sshpam_free_ctx(void *);
144 static struct pam_ctxt *cleanup_ctxt;
145
146 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
147 /*
148 * Simulate threads with processes.
149 */
150
151 static int sshpam_thread_status = -1;
152 static sshsig_t sshpam_oldsig;
153
154 static void
sshpam_sigchld_handler(int sig)155 sshpam_sigchld_handler(int sig)
156 {
157 ssh_signal(SIGCHLD, SIG_DFL);
158 if (cleanup_ctxt == NULL)
159 return; /* handler called after PAM cleanup, shouldn't happen */
160 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
161 <= 0) {
162 /* PAM thread has not exitted, privsep slave must have */
163 kill(cleanup_ctxt->pam_thread, SIGTERM);
164 while (waitpid(cleanup_ctxt->pam_thread,
165 &sshpam_thread_status, 0) == -1) {
166 if (errno == EINTR)
167 continue;
168 return;
169 }
170 }
171 if (sshpam_thread_status == -1)
172 return;
173 if (WIFSIGNALED(sshpam_thread_status)) {
174 if (signal_is_crash(WTERMSIG(sshpam_thread_status)))
175 _exit(EXIT_CHILD_CRASH);
176 } else if (!WIFEXITED(sshpam_thread_status))
177 _exit(EXIT_CHILD_CRASH);
178 }
179
180 /* ARGSUSED */
181 static void
pthread_exit(void * value)182 pthread_exit(void *value)
183 {
184 _exit(0);
185 }
186
187 /* ARGSUSED */
188 static int
pthread_create(sp_pthread_t * thread,const void * attr,void * (* thread_start)(void *),void * arg)189 pthread_create(sp_pthread_t *thread, const void *attr,
190 void *(*thread_start)(void *), void *arg)
191 {
192 pid_t pid;
193 struct pam_ctxt *ctx = arg;
194
195 sshpam_thread_status = -1;
196 switch ((pid = fork())) {
197 case -1:
198 error("fork(): %s", strerror(errno));
199 return errno;
200 case 0:
201 close(ctx->pam_psock);
202 ctx->pam_psock = -1;
203 thread_start(arg);
204 _exit(1);
205 default:
206 *thread = pid;
207 close(ctx->pam_csock);
208 ctx->pam_csock = -1;
209 sshpam_oldsig = ssh_signal(SIGCHLD, sshpam_sigchld_handler);
210 return (0);
211 }
212 }
213
214 static int
pthread_cancel(sp_pthread_t thread)215 pthread_cancel(sp_pthread_t thread)
216 {
217 ssh_signal(SIGCHLD, sshpam_oldsig);
218 return (kill(thread, SIGTERM));
219 }
220
221 /* ARGSUSED */
222 static int
pthread_join(sp_pthread_t thread,void ** value)223 pthread_join(sp_pthread_t thread, void **value)
224 {
225 int status;
226
227 if (sshpam_thread_status != -1)
228 return (sshpam_thread_status);
229 ssh_signal(SIGCHLD, sshpam_oldsig);
230 while (waitpid(thread, &status, 0) == -1) {
231 if (errno == EINTR)
232 continue;
233 fatal("%s: waitpid: %s", __func__, strerror(errno));
234 }
235 return (status);
236 }
237 #endif
238
239
240 static pam_handle_t *sshpam_handle = NULL;
241 static int sshpam_err = 0;
242 static int sshpam_authenticated = 0;
243 static int sshpam_session_open = 0;
244 static int sshpam_cred_established = 0;
245 static int sshpam_account_status = -1;
246 static int sshpam_maxtries_reached = 0;
247 static char **sshpam_env = NULL;
248 static Authctxt *sshpam_authctxt = NULL;
249 static const char *sshpam_password = NULL;
250 static char *sshpam_rhost = NULL;
251 static char *sshpam_laddr = NULL;
252
253 /* Some PAM implementations don't implement this */
254 #ifndef HAVE_PAM_GETENVLIST
255 static char **
pam_getenvlist(pam_handle_t * pamh)256 pam_getenvlist(pam_handle_t *pamh)
257 {
258 /*
259 * XXX - If necessary, we can still support environment passing
260 * for platforms without pam_getenvlist by searching for known
261 * env vars (e.g. KRB5CCNAME) from the PAM environment.
262 */
263 return NULL;
264 }
265 #endif
266
267 #ifndef HAVE_PAM_PUTENV
268 static int
pam_putenv(pam_handle_t * pamh,const char * name_value)269 pam_putenv(pam_handle_t *pamh, const char *name_value)
270 {
271 return PAM_SUCCESS;
272 }
273 #endif /* HAVE_PAM_PUTENV */
274
275 /*
276 * Some platforms, notably Solaris, do not enforce password complexity
277 * rules during pam_chauthtok() if the real uid of the calling process
278 * is 0, on the assumption that it's being called by "passwd" run by root.
279 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
280 * the right thing.
281 */
282 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
283 static int
sshpam_chauthtok_ruid(pam_handle_t * pamh,int flags)284 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
285 {
286 int result;
287
288 if (sshpam_authctxt == NULL)
289 fatal("PAM: sshpam_authctxt not initialized");
290 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
291 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
292 result = pam_chauthtok(pamh, flags);
293 if (setreuid(0, -1) == -1)
294 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
295 return result;
296 }
297 # define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b)))
298 #endif
299
300 static void
sshpam_password_change_required(int reqd)301 sshpam_password_change_required(int reqd)
302 {
303 extern struct sshauthopt *auth_opts;
304 static int saved_port, saved_agent, saved_x11;
305
306 debug3("%s %d", __func__, reqd);
307 if (sshpam_authctxt == NULL)
308 fatal("%s: PAM authctxt not initialized", __func__);
309 sshpam_authctxt->force_pwchange = reqd;
310 if (reqd) {
311 saved_port = auth_opts->permit_port_forwarding_flag;
312 saved_agent = auth_opts->permit_agent_forwarding_flag;
313 saved_x11 = auth_opts->permit_x11_forwarding_flag;
314 auth_opts->permit_port_forwarding_flag = 0;
315 auth_opts->permit_agent_forwarding_flag = 0;
316 auth_opts->permit_x11_forwarding_flag = 0;
317 } else {
318 if (saved_port)
319 auth_opts->permit_port_forwarding_flag = saved_port;
320 if (saved_agent)
321 auth_opts->permit_agent_forwarding_flag = saved_agent;
322 if (saved_x11)
323 auth_opts->permit_x11_forwarding_flag = saved_x11;
324 }
325 }
326
327 /* Import regular and PAM environment from subprocess */
328 static void
import_environments(struct sshbuf * b)329 import_environments(struct sshbuf *b)
330 {
331 char *env;
332 u_int n, i, num_env;
333 int r;
334
335 debug3("PAM: %s entering", __func__);
336
337 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
338 /* Import variables set by do_pam_account */
339 if ((r = sshbuf_get_u32(b, &n)) != 0)
340 fatal("%s: buffer error: %s", __func__, ssh_err(r));
341 if (n > INT_MAX)
342 fatal("%s: invalid PAM account status %u", __func__, n);
343 sshpam_account_status = (int)n;
344 if ((r = sshbuf_get_u32(b, &n)) != 0)
345 fatal("%s: buffer error: %s", __func__, ssh_err(r));
346 sshpam_password_change_required(n != 0);
347
348 /* Import environment from subprocess */
349 if ((r = sshbuf_get_u32(b, &num_env)) != 0)
350 fatal("%s: buffer error: %s", __func__, ssh_err(r));
351 if (num_env > 1024) {
352 fatal_f("received %u environment variables, expected <= 1024",
353 num_env);
354 }
355 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env));
356 debug3("PAM: num env strings %u", num_env);
357 for(i = 0; i < num_env; i++) {
358 if ((r = sshbuf_get_cstring(b, &(sshpam_env[i]), NULL)) != 0)
359 fatal("%s: buffer error: %s", __func__, ssh_err(r));
360 }
361 sshpam_env[num_env] = NULL;
362
363 /* Import PAM environment from subprocess */
364 if ((r = sshbuf_get_u32(b, &num_env)) != 0)
365 fatal("%s: buffer error: %s", __func__, ssh_err(r));
366 if (num_env > 1024) {
367 fatal_f("received %u PAM env variables, expected <= 1024",
368 num_env);
369 }
370 debug("PAM: num PAM env strings %u", num_env);
371 for (i = 0; i < num_env; i++) {
372 if ((r = sshbuf_get_cstring(b, &env, NULL)) != 0)
373 fatal("%s: buffer error: %s", __func__, ssh_err(r));
374 /* Errors are not fatal here */
375 if ((r = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
376 error("PAM: pam_putenv: %s",
377 pam_strerror(sshpam_handle, r));
378 }
379 /*
380 * XXX this possibly leaks env because it is not documented
381 * what pam_putenv() does with it. Does it copy it? Does it
382 * take ownweship? We don't know, so it's safest just to leak.
383 */
384 }
385 #endif
386 }
387
388 /*
389 * Conversation function for authentication thread.
390 */
391 static int
sshpam_thread_conv(int n,sshpam_const struct pam_message ** msg,struct pam_response ** resp,void * data)392 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
393 struct pam_response **resp, void *data)
394 {
395 struct sshbuf *buffer;
396 struct pam_ctxt *ctxt;
397 struct pam_response *reply;
398 int r, i;
399 u_char status;
400
401 debug3("PAM: %s entering, %d messages", __func__, n);
402 *resp = NULL;
403
404 if (data == NULL) {
405 error("PAM: conversation function passed a null context");
406 return (PAM_CONV_ERR);
407 }
408 ctxt = data;
409 if (n <= 0 || n > PAM_MAX_NUM_MSG)
410 return (PAM_CONV_ERR);
411
412 if ((reply = calloc(n, sizeof(*reply))) == NULL)
413 return PAM_CONV_ERR;
414 if ((buffer = sshbuf_new()) == NULL) {
415 free(reply);
416 return PAM_CONV_ERR;
417 }
418
419 for (i = 0; i < n; ++i) {
420 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
421 case PAM_PROMPT_ECHO_OFF:
422 case PAM_PROMPT_ECHO_ON:
423 if ((r = sshbuf_put_cstring(buffer,
424 PAM_MSG_MEMBER(msg, i, msg))) != 0)
425 fatal("%s: buffer error: %s",
426 __func__, ssh_err(r));
427 if (ssh_msg_send(ctxt->pam_csock,
428 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1)
429 goto fail;
430
431 if (ssh_msg_recv(ctxt->pam_csock, buffer) == -1)
432 goto fail;
433 if ((r = sshbuf_get_u8(buffer, &status)) != 0)
434 fatal("%s: buffer error: %s",
435 __func__, ssh_err(r));
436 if (status != PAM_AUTHTOK)
437 goto fail;
438 if ((r = sshbuf_get_cstring(buffer,
439 &reply[i].resp, NULL)) != 0)
440 fatal("%s: buffer error: %s",
441 __func__, ssh_err(r));
442 break;
443 case PAM_ERROR_MSG:
444 case PAM_TEXT_INFO:
445 if ((r = sshbuf_put_cstring(buffer,
446 PAM_MSG_MEMBER(msg, i, msg))) != 0)
447 fatal("%s: buffer error: %s",
448 __func__, ssh_err(r));
449 if (ssh_msg_send(ctxt->pam_csock,
450 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1)
451 goto fail;
452 break;
453 default:
454 goto fail;
455 }
456 sshbuf_reset(buffer);
457 }
458 sshbuf_free(buffer);
459 *resp = reply;
460 return (PAM_SUCCESS);
461
462 fail:
463 for(i = 0; i < n; i++) {
464 free(reply[i].resp);
465 }
466 free(reply);
467 sshbuf_free(buffer);
468 return (PAM_CONV_ERR);
469 }
470
471 /*
472 * Authentication thread.
473 */
474 static void *
sshpam_thread(void * ctxtp)475 sshpam_thread(void *ctxtp)
476 {
477 struct pam_ctxt *ctxt = ctxtp;
478 struct sshbuf *buffer = NULL;
479 struct pam_conv sshpam_conv;
480 int r, flags = (options.permit_empty_passwd == 0 ?
481 PAM_DISALLOW_NULL_AUTHTOK : 0);
482 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
483 extern char **environ;
484 char **env_from_pam;
485 u_int i;
486 const char *pam_user;
487 const char **ptr_pam_user = &pam_user;
488 char *tz = getenv("TZ");
489
490 sshpam_err = pam_get_item(sshpam_handle, PAM_USER,
491 (sshpam_const void **)ptr_pam_user);
492 if (sshpam_err != PAM_SUCCESS)
493 goto auth_fail;
494
495 environ[0] = NULL;
496 if (tz != NULL)
497 if (setenv("TZ", tz, 1) == -1)
498 error("PAM: could not set TZ environment: %s",
499 strerror(errno));
500
501 if (sshpam_authctxt != NULL) {
502 setproctitle("%s [pam]",
503 sshpam_authctxt->valid ? pam_user : "unknown");
504 }
505 #endif
506
507 sshpam_conv.conv = sshpam_thread_conv;
508 sshpam_conv.appdata_ptr = ctxt;
509
510 if (sshpam_authctxt == NULL)
511 fatal("%s: PAM authctxt not initialized", __func__);
512
513 if ((buffer = sshbuf_new()) == NULL)
514 fatal("%s: sshbuf_new failed", __func__);
515
516 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
517 (const void *)&sshpam_conv);
518 if (sshpam_err != PAM_SUCCESS)
519 goto auth_fail;
520 sshpam_err = pam_authenticate(sshpam_handle, flags);
521 if (sshpam_err == PAM_MAXTRIES)
522 sshpam_set_maxtries_reached(1);
523 if (sshpam_err != PAM_SUCCESS)
524 goto auth_fail;
525
526 if (!do_pam_account()) {
527 sshpam_err = PAM_ACCT_EXPIRED;
528 goto auth_fail;
529 }
530 if (sshpam_authctxt->force_pwchange) {
531 sshpam_err = pam_chauthtok(sshpam_handle,
532 PAM_CHANGE_EXPIRED_AUTHTOK);
533 if (sshpam_err != PAM_SUCCESS)
534 goto auth_fail;
535 sshpam_password_change_required(0);
536 }
537
538 if ((r = sshbuf_put_cstring(buffer, "OK")) != 0)
539 fatal("%s: buffer error: %s", __func__, ssh_err(r));
540
541 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
542 /* Export variables set by do_pam_account */
543 if ((r = sshbuf_put_u32(buffer, sshpam_account_status)) != 0 ||
544 (r = sshbuf_put_u32(buffer, sshpam_authctxt->force_pwchange)) != 0)
545 fatal("%s: buffer error: %s", __func__, ssh_err(r));
546
547 /* Export any environment strings set in child */
548 for (i = 0; environ[i] != NULL; i++) {
549 /* Count */
550 if (i > INT_MAX)
551 fatal("%s: too many environment strings", __func__);
552 }
553 if ((r = sshbuf_put_u32(buffer, i)) != 0)
554 fatal("%s: buffer error: %s", __func__, ssh_err(r));
555 for (i = 0; environ[i] != NULL; i++) {
556 if ((r = sshbuf_put_cstring(buffer, environ[i])) != 0)
557 fatal("%s: buffer error: %s", __func__, ssh_err(r));
558 }
559 /* Export any environment strings set by PAM in child */
560 env_from_pam = pam_getenvlist(sshpam_handle);
561 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) {
562 /* Count */
563 if (i > INT_MAX)
564 fatal("%s: too many PAM environment strings", __func__);
565 }
566 if ((r = sshbuf_put_u32(buffer, i)) != 0)
567 fatal("%s: buffer error: %s", __func__, ssh_err(r));
568 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) {
569 if ((r = sshbuf_put_cstring(buffer, env_from_pam[i])) != 0)
570 fatal("%s: buffer error: %s", __func__, ssh_err(r));
571 }
572 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */
573
574 /* XXX - can't do much about an error here */
575 ssh_msg_send(ctxt->pam_csock, sshpam_err, buffer);
576 sshbuf_free(buffer);
577 pthread_exit(NULL);
578
579 auth_fail:
580 if ((r = sshbuf_put_cstring(buffer,
581 pam_strerror(sshpam_handle, sshpam_err))) != 0)
582 fatal("%s: buffer error: %s", __func__, ssh_err(r));
583 /* XXX - can't do much about an error here */
584 if (sshpam_err == PAM_ACCT_EXPIRED)
585 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, buffer);
586 else if (sshpam_maxtries_reached)
587 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, buffer);
588 else
589 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, buffer);
590 sshbuf_free(buffer);
591 pthread_exit(NULL);
592
593 return (NULL); /* Avoid warning for non-pthread case */
594 }
595
596 void
sshpam_thread_cleanup(void)597 sshpam_thread_cleanup(void)
598 {
599 struct pam_ctxt *ctxt = cleanup_ctxt;
600
601 debug3("PAM: %s entering", __func__);
602 if (ctxt != NULL && ctxt->pam_thread != 0) {
603 pthread_cancel(ctxt->pam_thread);
604 pthread_join(ctxt->pam_thread, NULL);
605 close(ctxt->pam_psock);
606 close(ctxt->pam_csock);
607 memset(ctxt, 0, sizeof(*ctxt));
608 cleanup_ctxt = NULL;
609 }
610 }
611
612 static int
sshpam_null_conv(int n,sshpam_const struct pam_message ** msg,struct pam_response ** resp,void * data)613 sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
614 struct pam_response **resp, void *data)
615 {
616 debug3("PAM: %s entering, %d messages", __func__, n);
617 return (PAM_CONV_ERR);
618 }
619
620 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
621
622 static int
sshpam_store_conv(int n,sshpam_const struct pam_message ** msg,struct pam_response ** resp,void * data)623 sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
624 struct pam_response **resp, void *data)
625 {
626 struct pam_response *reply;
627 int r, i;
628
629 debug3("PAM: %s called with %d messages", __func__, n);
630 *resp = NULL;
631
632 if (n <= 0 || n > PAM_MAX_NUM_MSG)
633 return (PAM_CONV_ERR);
634
635 if ((reply = calloc(n, sizeof(*reply))) == NULL)
636 return (PAM_CONV_ERR);
637
638 for (i = 0; i < n; ++i) {
639 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
640 case PAM_ERROR_MSG:
641 case PAM_TEXT_INFO:
642 if ((r = sshbuf_putf(loginmsg, "%s\n",
643 PAM_MSG_MEMBER(msg, i, msg))) != 0)
644 fatal("%s: buffer error: %s",
645 __func__, ssh_err(r));
646 reply[i].resp_retcode = PAM_SUCCESS;
647 break;
648 default:
649 goto fail;
650 }
651 }
652 *resp = reply;
653 return (PAM_SUCCESS);
654
655 fail:
656 for(i = 0; i < n; i++) {
657 free(reply[i].resp);
658 }
659 free(reply);
660 return (PAM_CONV_ERR);
661 }
662
663 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
664
665 void
sshpam_cleanup(void)666 sshpam_cleanup(void)
667 {
668 if (sshpam_handle == NULL || !mm_is_monitor())
669 return;
670 debug("PAM: cleanup");
671 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
672 if (sshpam_session_open) {
673 debug("PAM: closing session");
674 pam_close_session(sshpam_handle, PAM_SILENT);
675 sshpam_session_open = 0;
676 }
677 if (sshpam_cred_established) {
678 debug("PAM: deleting credentials");
679 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
680 sshpam_cred_established = 0;
681 }
682 sshpam_authenticated = 0;
683 pam_end(sshpam_handle, sshpam_err);
684 sshpam_handle = NULL;
685 }
686
687 static int
sshpam_init(struct ssh * ssh,Authctxt * authctxt)688 sshpam_init(struct ssh *ssh, Authctxt *authctxt)
689 {
690 const char *pam_user, *user = authctxt->user;
691 const char **ptr_pam_user = &pam_user;
692 int r;
693
694 if (options.pam_service_name == NULL)
695 fatal_f("internal error: NULL PAM service name");
696 #if defined(PAM_SUN_CODEBASE) && defined(PAM_MAX_RESP_SIZE)
697 /* Protect buggy PAM implementations from excessively long usernames */
698 if (strlen(user) >= PAM_MAX_RESP_SIZE)
699 fatal("Username too long from %s port %d",
700 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
701 #endif
702 if (sshpam_handle == NULL) {
703 if (ssh == NULL) {
704 fatal("%s: called initially with no "
705 "packet context", __func__);
706 }
707 }
708 if (sshpam_handle != NULL) {
709 /* We already have a PAM context; check if the user matches */
710 sshpam_err = pam_get_item(sshpam_handle,
711 PAM_USER, (sshpam_const void **)ptr_pam_user);
712 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
713 return (0);
714 pam_end(sshpam_handle, sshpam_err);
715 sshpam_handle = NULL;
716 }
717 debug("PAM: initializing for \"%s\" with service \"%s\"", user,
718 options.pam_service_name);
719 sshpam_err = pam_start(options.pam_service_name, user,
720 &store_conv, &sshpam_handle);
721 sshpam_authctxt = authctxt;
722
723 if (sshpam_err != PAM_SUCCESS) {
724 pam_end(sshpam_handle, sshpam_err);
725 sshpam_handle = NULL;
726 return (-1);
727 }
728
729 if (ssh != NULL && sshpam_rhost == NULL) {
730 /*
731 * We need to cache these as we don't have packet context
732 * during the kbdint flow.
733 */
734 sshpam_rhost = xstrdup(auth_get_canonical_hostname(ssh,
735 options.use_dns));
736 sshpam_laddr = get_local_ipaddr(
737 ssh_packet_get_connection_in(ssh));
738 }
739 if (sshpam_rhost != NULL) {
740 debug("PAM: setting PAM_RHOST to \"%s\"", sshpam_rhost);
741 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST,
742 sshpam_rhost);
743 if (sshpam_err != PAM_SUCCESS) {
744 pam_end(sshpam_handle, sshpam_err);
745 sshpam_handle = NULL;
746 return (-1);
747 }
748 }
749 if (ssh != NULL && sshpam_laddr != NULL) {
750 char *conninfo;
751
752 /* Put SSH_CONNECTION in the PAM environment too */
753 xasprintf(&conninfo, "SSH_CONNECTION=%.50s %d %.50s %d",
754 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
755 sshpam_laddr, ssh_local_port(ssh));
756 if ((r = pam_putenv(sshpam_handle, conninfo)) != PAM_SUCCESS)
757 logit("pam_putenv: %s", pam_strerror(sshpam_handle, r));
758 free(conninfo);
759 }
760
761 #ifdef PAM_TTY_KLUDGE
762 /*
763 * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
764 * sshd doesn't set the tty until too late in the auth process and
765 * may not even set one (for tty-less connections)
766 */
767 debug("PAM: setting PAM_TTY to \"ssh\"");
768 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
769 if (sshpam_err != PAM_SUCCESS) {
770 pam_end(sshpam_handle, sshpam_err);
771 sshpam_handle = NULL;
772 return (-1);
773 }
774 #endif
775 return (0);
776 }
777
778 static void
expose_authinfo(const char * caller)779 expose_authinfo(const char *caller)
780 {
781 char *auth_info;
782
783 /*
784 * Expose authentication information to PAM.
785 * The environment variable is versioned. Please increment the
786 * version suffix if the format of session_info changes.
787 */
788 if (sshpam_authctxt->session_info == NULL)
789 auth_info = xstrdup("");
790 else if ((auth_info = sshbuf_dup_string(
791 sshpam_authctxt->session_info)) == NULL)
792 fatal("%s: sshbuf_dup_string failed", __func__);
793
794 debug2("%s: auth information in SSH_AUTH_INFO_0", caller);
795 do_pam_putenv("SSH_AUTH_INFO_0", auth_info);
796 free(auth_info);
797 }
798
799 static void *
sshpam_init_ctx(Authctxt * authctxt)800 sshpam_init_ctx(Authctxt *authctxt)
801 {
802 struct pam_ctxt *ctxt;
803 int result, socks[2];
804
805 debug3("PAM: %s entering", __func__);
806 /*
807 * Refuse to start if we don't have PAM enabled or do_pam_account
808 * has previously failed.
809 */
810 if (!options.use_pam || sshpam_account_status == 0)
811 return NULL;
812
813 /* Initialize PAM */
814 if (sshpam_init(NULL, authctxt) == -1) {
815 error("PAM: initialization failed");
816 return (NULL);
817 }
818
819 expose_authinfo(__func__);
820 ctxt = xcalloc(1, sizeof *ctxt);
821
822 /* Start the authentication thread */
823 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
824 error("PAM: failed create sockets: %s", strerror(errno));
825 free(ctxt);
826 return (NULL);
827 }
828 ctxt->pam_psock = socks[0];
829 ctxt->pam_csock = socks[1];
830 result = pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt);
831 if (result != 0) {
832 error("PAM: failed to start authentication thread: %s",
833 strerror(result));
834 close(socks[0]);
835 close(socks[1]);
836 free(ctxt);
837 return (NULL);
838 }
839 cleanup_ctxt = ctxt;
840 return (ctxt);
841 }
842
843 static int
sshpam_query(void * ctx,char ** name,char ** info,u_int * num,char *** prompts,u_int ** echo_on)844 sshpam_query(void *ctx, char **name, char **info,
845 u_int *num, char ***prompts, u_int **echo_on)
846 {
847 struct sshbuf *buffer;
848 struct pam_ctxt *ctxt = ctx;
849 size_t plen;
850 u_char type;
851 char *msg;
852 size_t len, mlen, nmesg = 0;
853 int r;
854
855 debug3("PAM: %s entering", __func__);
856 if ((buffer = sshbuf_new()) == NULL)
857 fatal("%s: sshbuf_new failed", __func__);
858 *name = xstrdup("");
859 *info = xstrdup("");
860 *prompts = xmalloc(sizeof(char *));
861 **prompts = NULL;
862 plen = 0;
863 *echo_on = xmalloc(sizeof(u_int));
864 while (ssh_msg_recv(ctxt->pam_psock, buffer) == 0) {
865 if (++nmesg > PAM_MAX_NUM_MSG)
866 fatal_f("too many query messages");
867 if ((r = sshbuf_get_u8(buffer, &type)) != 0 ||
868 (r = sshbuf_get_cstring(buffer, &msg, &mlen)) != 0)
869 fatal("%s: buffer error: %s", __func__, ssh_err(r));
870 switch (type) {
871 case PAM_PROMPT_ECHO_ON:
872 case PAM_PROMPT_ECHO_OFF:
873 *num = 1;
874 len = plen + mlen + 1;
875 **prompts = xreallocarray(**prompts, 1, len);
876 strlcpy(**prompts + plen, msg, len - plen);
877 plen += mlen;
878 **echo_on = (type == PAM_PROMPT_ECHO_ON);
879 free(msg);
880 sshbuf_free(buffer);
881 return (0);
882 case PAM_ERROR_MSG:
883 case PAM_TEXT_INFO:
884 /* accumulate messages */
885 len = plen + mlen + 2;
886 **prompts = xreallocarray(**prompts, 1, len);
887 strlcpy(**prompts + plen, msg, len - plen);
888 plen += mlen;
889 strlcat(**prompts + plen, "\n", len - plen);
890 plen++;
891 free(msg);
892 break;
893 case PAM_ACCT_EXPIRED:
894 case PAM_MAXTRIES:
895 if (type == PAM_ACCT_EXPIRED)
896 sshpam_account_status = 0;
897 if (type == PAM_MAXTRIES)
898 sshpam_set_maxtries_reached(1);
899 /* FALLTHROUGH */
900 case PAM_AUTH_ERR:
901 debug3("PAM: %s", pam_strerror(sshpam_handle, type));
902 if (**prompts != NULL && strlen(**prompts) != 0) {
903 free(*info);
904 *info = **prompts;
905 **prompts = NULL;
906 *num = 0;
907 **echo_on = 0;
908 ctxt->pam_done = -1;
909 free(msg);
910 sshbuf_free(buffer);
911 return 0;
912 }
913 /* FALLTHROUGH */
914 case PAM_SUCCESS:
915 if (**prompts != NULL) {
916 /* drain any accumulated messages */
917 debug("PAM: %s", **prompts);
918 if ((r = sshbuf_put(loginmsg, **prompts,
919 strlen(**prompts))) != 0)
920 fatal("%s: buffer error: %s",
921 __func__, ssh_err(r));
922 free(**prompts);
923 **prompts = NULL;
924 }
925 if (type == PAM_SUCCESS) {
926 if (!sshpam_authctxt->valid ||
927 (sshpam_authctxt->pw->pw_uid == 0 &&
928 options.permit_root_login != PERMIT_YES))
929 fatal("Internal error: PAM auth "
930 "succeeded when it should have "
931 "failed");
932 import_environments(buffer);
933 *num = 0;
934 **echo_on = 0;
935 ctxt->pam_done = 1;
936 free(msg);
937 sshbuf_free(buffer);
938 return (0);
939 }
940 BLACKLIST_NOTIFY(NULL, BLACKLIST_BAD_USER,
941 sshpam_authctxt->user);
942 error("PAM: %s for %s%.100s from %.100s", msg,
943 sshpam_authctxt->valid ? "" : "illegal user ",
944 sshpam_authctxt->user, sshpam_rhost);
945 /* FALLTHROUGH */
946 default:
947 *num = 0;
948 **echo_on = 0;
949 free(msg);
950 ctxt->pam_done = -1;
951 sshbuf_free(buffer);
952 return (-1);
953 }
954 }
955 sshbuf_free(buffer);
956 return (-1);
957 }
958
959 /*
960 * Returns a junk password of identical length to that the user supplied.
961 * Used to mitigate timing attacks against crypt(3)/PAM stacks that
962 * vary processing time in proportion to password length.
963 */
964 static char *
fake_password(const char * wire_password)965 fake_password(const char *wire_password)
966 {
967 const char junk[] = "\b\n\r\177INCORRECT";
968 char *ret = NULL;
969 size_t i, l = wire_password != NULL ? strlen(wire_password) : 0;
970
971 if (l >= INT_MAX)
972 fatal("%s: password length too long: %zu", __func__, l);
973
974 ret = malloc(l + 1);
975 if (ret == NULL)
976 return NULL;
977 for (i = 0; i < l; i++)
978 ret[i] = junk[i % (sizeof(junk) - 1)];
979 ret[i] = '\0';
980 return ret;
981 }
982
983 /* XXX - see also comment in auth-chall.c:verify_response */
984 static int
sshpam_respond(void * ctx,u_int num,char ** resp)985 sshpam_respond(void *ctx, u_int num, char **resp)
986 {
987 struct sshbuf *buffer;
988 struct pam_ctxt *ctxt = ctx;
989 char *fake;
990 int r;
991
992 debug2("PAM: %s entering, %u responses", __func__, num);
993 switch (ctxt->pam_done) {
994 case 1:
995 sshpam_authenticated = 1;
996 return (0);
997 case 0:
998 break;
999 default:
1000 return (-1);
1001 }
1002 if (num != 1) {
1003 error("PAM: expected one response, got %u", num);
1004 return (-1);
1005 }
1006 if ((buffer = sshbuf_new()) == NULL)
1007 fatal("%s: sshbuf_new failed", __func__);
1008 if (sshpam_authctxt->valid &&
1009 (sshpam_authctxt->pw->pw_uid != 0 ||
1010 options.permit_root_login == PERMIT_YES)) {
1011 if ((r = sshbuf_put_cstring(buffer, *resp)) != 0)
1012 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1013 } else {
1014 fake = fake_password(*resp);
1015 if ((r = sshbuf_put_cstring(buffer, fake)) != 0)
1016 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1017 free(fake);
1018 }
1019 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, buffer) == -1) {
1020 sshbuf_free(buffer);
1021 return (-1);
1022 }
1023 sshbuf_free(buffer);
1024 return (1);
1025 }
1026
1027 static void
sshpam_free_ctx(void * ctxtp)1028 sshpam_free_ctx(void *ctxtp)
1029 {
1030 struct pam_ctxt *ctxt = ctxtp;
1031
1032 debug3("PAM: %s entering", __func__);
1033 sshpam_thread_cleanup();
1034 free(ctxt);
1035 /*
1036 * We don't call sshpam_cleanup() here because we may need the PAM
1037 * handle at a later stage, e.g. when setting up a session. It's
1038 * still on the cleanup list, so pam_end() *will* be called before
1039 * the server process terminates.
1040 */
1041 }
1042
1043 KbdintDevice sshpam_device = {
1044 "pam",
1045 sshpam_init_ctx,
1046 sshpam_query,
1047 sshpam_respond,
1048 sshpam_free_ctx
1049 };
1050
1051 KbdintDevice mm_sshpam_device = {
1052 "pam",
1053 mm_sshpam_init_ctx,
1054 mm_sshpam_query,
1055 mm_sshpam_respond,
1056 mm_sshpam_free_ctx
1057 };
1058
1059 /*
1060 * This replaces auth-pam.c
1061 */
1062 void
start_pam(struct ssh * ssh)1063 start_pam(struct ssh *ssh)
1064 {
1065 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1066
1067 if (!options.use_pam)
1068 fatal("PAM: initialisation requested when UsePAM=no");
1069
1070 if (sshpam_init(ssh, authctxt) == -1)
1071 fatal("PAM: initialisation failed");
1072 }
1073
1074 void
finish_pam(void)1075 finish_pam(void)
1076 {
1077 sshpam_cleanup();
1078 }
1079
1080
1081 u_int
do_pam_account(void)1082 do_pam_account(void)
1083 {
1084 debug("%s: called", __func__);
1085 if (sshpam_account_status != -1)
1086 return (sshpam_account_status);
1087
1088 expose_authinfo(__func__);
1089
1090 sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
1091 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
1092 pam_strerror(sshpam_handle, sshpam_err));
1093
1094 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
1095 sshpam_account_status = 0;
1096 return (sshpam_account_status);
1097 }
1098
1099 if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
1100 sshpam_password_change_required(1);
1101
1102 sshpam_account_status = 1;
1103 return (sshpam_account_status);
1104 }
1105
1106 void
do_pam_setcred(void)1107 do_pam_setcred(void)
1108 {
1109 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1110 (const void *)&store_conv);
1111 if (sshpam_err != PAM_SUCCESS)
1112 fatal("PAM: failed to set PAM_CONV: %s",
1113 pam_strerror(sshpam_handle, sshpam_err));
1114 debug("PAM: establishing credentials");
1115 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
1116 if (sshpam_err == PAM_SUCCESS) {
1117 sshpam_cred_established = 1;
1118 return;
1119 }
1120 if (sshpam_authenticated)
1121 fatal("PAM: pam_setcred(): %s",
1122 pam_strerror(sshpam_handle, sshpam_err));
1123 else
1124 debug("PAM: pam_setcred(): %s",
1125 pam_strerror(sshpam_handle, sshpam_err));
1126 }
1127
1128 #if 0
1129 static int
1130 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
1131 struct pam_response **resp, void *data)
1132 {
1133 char input[PAM_MAX_MSG_SIZE];
1134 struct pam_response *reply;
1135 int i;
1136
1137 debug3("PAM: %s called with %d messages", __func__, n);
1138
1139 *resp = NULL;
1140
1141 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
1142 return (PAM_CONV_ERR);
1143
1144 if ((reply = calloc(n, sizeof(*reply))) == NULL)
1145 return (PAM_CONV_ERR);
1146
1147 for (i = 0; i < n; ++i) {
1148 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1149 case PAM_PROMPT_ECHO_OFF:
1150 reply[i].resp =
1151 read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
1152 RP_ALLOW_STDIN);
1153 reply[i].resp_retcode = PAM_SUCCESS;
1154 break;
1155 case PAM_PROMPT_ECHO_ON:
1156 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1157 if (fgets(input, sizeof input, stdin) == NULL)
1158 input[0] = '\0';
1159 if ((reply[i].resp = strdup(input)) == NULL)
1160 goto fail;
1161 reply[i].resp_retcode = PAM_SUCCESS;
1162 break;
1163 case PAM_ERROR_MSG:
1164 case PAM_TEXT_INFO:
1165 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1166 reply[i].resp_retcode = PAM_SUCCESS;
1167 break;
1168 default:
1169 goto fail;
1170 }
1171 }
1172 *resp = reply;
1173 return (PAM_SUCCESS);
1174
1175 fail:
1176 for(i = 0; i < n; i++) {
1177 free(reply[i].resp);
1178 }
1179 free(reply);
1180 return (PAM_CONV_ERR);
1181 }
1182
1183 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
1184 #endif
1185
1186 /*
1187 * XXX this should be done in the authentication phase, but ssh1 doesn't
1188 * support that
1189 */
1190 void
do_pam_chauthtok(void)1191 do_pam_chauthtok(void)
1192 {
1193 fatal("Password expired");
1194 #if 0
1195 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1196 (const void *)&tty_conv);
1197 if (sshpam_err != PAM_SUCCESS)
1198 fatal("PAM: failed to set PAM_CONV: %s",
1199 pam_strerror(sshpam_handle, sshpam_err));
1200 debug("PAM: changing password");
1201 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
1202 if (sshpam_err != PAM_SUCCESS)
1203 fatal("PAM: pam_chauthtok(): %s",
1204 pam_strerror(sshpam_handle, sshpam_err));
1205 #endif
1206 }
1207
1208 void
do_pam_session(struct ssh * ssh)1209 do_pam_session(struct ssh *ssh)
1210 {
1211 debug3("PAM: opening session");
1212
1213 expose_authinfo(__func__);
1214
1215 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1216 (const void *)&store_conv);
1217 if (sshpam_err != PAM_SUCCESS)
1218 fatal("PAM: failed to set PAM_CONV: %s",
1219 pam_strerror(sshpam_handle, sshpam_err));
1220 sshpam_err = pam_open_session(sshpam_handle, 0);
1221 if (sshpam_err == PAM_SUCCESS)
1222 sshpam_session_open = 1;
1223 else {
1224 sshpam_session_open = 0;
1225 auth_restrict_session(ssh);
1226 error("PAM: pam_open_session(): %s",
1227 pam_strerror(sshpam_handle, sshpam_err));
1228 }
1229
1230 }
1231
1232 int
is_pam_session_open(void)1233 is_pam_session_open(void)
1234 {
1235 return sshpam_session_open;
1236 }
1237
1238 /*
1239 * Set a PAM environment string. We need to do this so that the session
1240 * modules can handle things like Kerberos/GSI credentials that appear
1241 * during the ssh authentication process.
1242 */
1243 int
do_pam_putenv(char * name,char * value)1244 do_pam_putenv(char *name, char *value)
1245 {
1246 int ret = 1;
1247 char *compound;
1248 size_t len;
1249
1250 len = strlen(name) + strlen(value) + 2;
1251 compound = xmalloc(len);
1252
1253 snprintf(compound, len, "%s=%s", name, value);
1254 ret = pam_putenv(sshpam_handle, compound);
1255 free(compound);
1256
1257 return (ret);
1258 }
1259
1260 char **
fetch_pam_child_environment(void)1261 fetch_pam_child_environment(void)
1262 {
1263 return sshpam_env;
1264 }
1265
1266 char **
fetch_pam_environment(void)1267 fetch_pam_environment(void)
1268 {
1269 return (pam_getenvlist(sshpam_handle));
1270 }
1271
1272 void
free_pam_environment(char ** env)1273 free_pam_environment(char **env)
1274 {
1275 char **envp;
1276
1277 if (env == NULL)
1278 return;
1279
1280 for (envp = env; *envp; envp++)
1281 free(*envp);
1282 free(env);
1283 }
1284
1285 /*
1286 * "Blind" conversation function for password authentication. Assumes that
1287 * echo-off prompts are for the password and stores messages for later
1288 * display.
1289 */
1290 static int
sshpam_passwd_conv(int n,sshpam_const struct pam_message ** msg,struct pam_response ** resp,void * data)1291 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1292 struct pam_response **resp, void *data)
1293 {
1294 struct pam_response *reply;
1295 int r, i;
1296 size_t len;
1297
1298 debug3("PAM: %s called with %d messages", __func__, n);
1299
1300 *resp = NULL;
1301
1302 if (n <= 0 || n > PAM_MAX_NUM_MSG)
1303 return (PAM_CONV_ERR);
1304
1305 if ((reply = calloc(n, sizeof(*reply))) == NULL)
1306 return (PAM_CONV_ERR);
1307
1308 for (i = 0; i < n; ++i) {
1309 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1310 case PAM_PROMPT_ECHO_OFF:
1311 if (sshpam_password == NULL)
1312 goto fail;
1313 if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1314 goto fail;
1315 reply[i].resp_retcode = PAM_SUCCESS;
1316 break;
1317 case PAM_ERROR_MSG:
1318 case PAM_TEXT_INFO:
1319 len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1320 if (len > 0) {
1321 if ((r = sshbuf_putf(loginmsg, "%s\n",
1322 PAM_MSG_MEMBER(msg, i, msg))) != 0)
1323 fatal("%s: buffer error: %s",
1324 __func__, ssh_err(r));
1325 }
1326 if ((reply[i].resp = strdup("")) == NULL)
1327 goto fail;
1328 reply[i].resp_retcode = PAM_SUCCESS;
1329 break;
1330 default:
1331 goto fail;
1332 }
1333 }
1334 *resp = reply;
1335 return (PAM_SUCCESS);
1336
1337 fail:
1338 for(i = 0; i < n; i++) {
1339 free(reply[i].resp);
1340 }
1341 free(reply);
1342 return (PAM_CONV_ERR);
1343 }
1344
1345 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1346
1347 /*
1348 * Attempt password authentication via PAM
1349 */
1350 int
sshpam_auth_passwd(Authctxt * authctxt,const char * password)1351 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1352 {
1353 int flags = (options.permit_empty_passwd == 0 ?
1354 PAM_DISALLOW_NULL_AUTHTOK : 0);
1355 char *fake = NULL;
1356
1357 if (!options.use_pam || sshpam_handle == NULL)
1358 fatal("PAM: %s called when PAM disabled or failed to "
1359 "initialise.", __func__);
1360
1361 sshpam_password = password;
1362 sshpam_authctxt = authctxt;
1363
1364 /*
1365 * If the user logging in is invalid, or is root but is not permitted
1366 * by PermitRootLogin, use an invalid password to prevent leaking
1367 * information via timing (eg if the PAM config has a delay on fail).
1368 */
1369 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1370 options.permit_root_login != PERMIT_YES))
1371 sshpam_password = fake = fake_password(password);
1372
1373 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1374 (const void *)&passwd_conv);
1375 if (sshpam_err != PAM_SUCCESS)
1376 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1377 pam_strerror(sshpam_handle, sshpam_err));
1378
1379 expose_authinfo(__func__);
1380
1381 sshpam_err = pam_authenticate(sshpam_handle, flags);
1382 sshpam_password = NULL;
1383 free(fake);
1384 if (sshpam_err == PAM_MAXTRIES)
1385 sshpam_set_maxtries_reached(1);
1386 if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1387 debug("PAM: password authentication accepted for %.100s",
1388 authctxt->user);
1389 return 1;
1390 } else {
1391 debug("PAM: password authentication failed for %.100s: %s",
1392 authctxt->valid ? authctxt->user : "an illegal user",
1393 pam_strerror(sshpam_handle, sshpam_err));
1394 return 0;
1395 }
1396 }
1397
1398 int
sshpam_get_maxtries_reached(void)1399 sshpam_get_maxtries_reached(void)
1400 {
1401 return sshpam_maxtries_reached;
1402 }
1403
1404 void
sshpam_set_maxtries_reached(int reached)1405 sshpam_set_maxtries_reached(int reached)
1406 {
1407 if (reached == 0 || sshpam_maxtries_reached)
1408 return;
1409 sshpam_maxtries_reached = 1;
1410 options.password_authentication = 0;
1411 options.kbd_interactive_authentication = 0;
1412 }
1413 #endif /* USE_PAM */
1414