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 #include "blacklist_client.h"
109
110 extern ServerOptions options;
111 extern struct sshbuf *loginmsg;
112 extern u_int utmp_len;
113
114 /* so we don't silently change behaviour */
115 #ifdef USE_POSIX_THREADS
116 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
117 #endif
118
119 /*
120 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
121 * and generally a bad idea. Use at own risk and do not expect support if
122 * this breaks.
123 */
124 #ifdef UNSUPPORTED_POSIX_THREADS_HACK
125 #include <pthread.h>
126 /*
127 * Avoid namespace clash when *not* using pthreads for systems *with*
128 * pthreads, which unconditionally define pthread_t via sys/types.h
129 * (e.g. Linux)
130 */
131 typedef pthread_t sp_pthread_t;
132 #else
133 typedef pid_t sp_pthread_t;
134 #define pthread_exit fake_pthread_exit
135 #define pthread_create fake_pthread_create
136 #define pthread_cancel fake_pthread_cancel
137 #define pthread_join fake_pthread_join
138 #endif
139
140 struct pam_ctxt {
141 sp_pthread_t pam_thread;
142 int pam_psock;
143 int pam_csock;
144 int pam_done;
145 };
146
147 static void sshpam_free_ctx(void *);
148 static struct pam_ctxt *cleanup_ctxt;
149
150 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
151 /*
152 * Simulate threads with processes.
153 */
154
155 static int sshpam_thread_status = -1;
156 static sshsig_t sshpam_oldsig;
157
158 static void
sshpam_sigchld_handler(int sig)159 sshpam_sigchld_handler(int sig)
160 {
161 ssh_signal(SIGCHLD, SIG_DFL);
162 if (cleanup_ctxt == NULL)
163 return; /* handler called after PAM cleanup, shouldn't happen */
164 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
165 <= 0) {
166 /* PAM thread has not exitted, privsep slave must have */
167 kill(cleanup_ctxt->pam_thread, SIGTERM);
168 while (waitpid(cleanup_ctxt->pam_thread,
169 &sshpam_thread_status, 0) == -1) {
170 if (errno == EINTR)
171 continue;
172 return;
173 }
174 }
175 if (WIFSIGNALED(sshpam_thread_status) &&
176 WTERMSIG(sshpam_thread_status) == SIGTERM)
177 return; /* terminated by pthread_cancel */
178 if (!WIFEXITED(sshpam_thread_status))
179 sigdie("PAM: authentication thread exited unexpectedly");
180 if (WEXITSTATUS(sshpam_thread_status) != 0)
181 sigdie("PAM: authentication thread exited uncleanly");
182 }
183
184 /* ARGSUSED */
185 static void
pthread_exit(void * value)186 pthread_exit(void *value)
187 {
188 _exit(0);
189 }
190
191 /* ARGSUSED */
192 static int
pthread_create(sp_pthread_t * thread,const void * attr,void * (* thread_start)(void *),void * arg)193 pthread_create(sp_pthread_t *thread, const void *attr,
194 void *(*thread_start)(void *), void *arg)
195 {
196 pid_t pid;
197 struct pam_ctxt *ctx = arg;
198
199 sshpam_thread_status = -1;
200 switch ((pid = fork())) {
201 case -1:
202 error("fork(): %s", strerror(errno));
203 return errno;
204 case 0:
205 close(ctx->pam_psock);
206 ctx->pam_psock = -1;
207 thread_start(arg);
208 _exit(1);
209 default:
210 *thread = pid;
211 close(ctx->pam_csock);
212 ctx->pam_csock = -1;
213 sshpam_oldsig = ssh_signal(SIGCHLD, sshpam_sigchld_handler);
214 return (0);
215 }
216 }
217
218 static int
pthread_cancel(sp_pthread_t thread)219 pthread_cancel(sp_pthread_t thread)
220 {
221 ssh_signal(SIGCHLD, sshpam_oldsig);
222 return (kill(thread, SIGTERM));
223 }
224
225 /* ARGSUSED */
226 static int
pthread_join(sp_pthread_t thread,void ** value)227 pthread_join(sp_pthread_t thread, void **value)
228 {
229 int status;
230
231 if (sshpam_thread_status != -1)
232 return (sshpam_thread_status);
233 ssh_signal(SIGCHLD, sshpam_oldsig);
234 while (waitpid(thread, &status, 0) == -1) {
235 if (errno == EINTR)
236 continue;
237 fatal("%s: waitpid: %s", __func__, strerror(errno));
238 }
239 return (status);
240 }
241 #endif
242
243
244 static pam_handle_t *sshpam_handle = NULL;
245 static int sshpam_err = 0;
246 static int sshpam_authenticated = 0;
247 static int sshpam_session_open = 0;
248 static int sshpam_cred_established = 0;
249 static int sshpam_account_status = -1;
250 static int sshpam_maxtries_reached = 0;
251 static char **sshpam_env = NULL;
252 static Authctxt *sshpam_authctxt = NULL;
253 static const char *sshpam_password = NULL;
254 static char *sshpam_rhost = NULL;
255 static char *sshpam_laddr = NULL;
256 static char *sshpam_conninfo = NULL;
257
258 /* Some PAM implementations don't implement this */
259 #ifndef HAVE_PAM_GETENVLIST
260 static char **
pam_getenvlist(pam_handle_t * pamh)261 pam_getenvlist(pam_handle_t *pamh)
262 {
263 /*
264 * XXX - If necessary, we can still support environment passing
265 * for platforms without pam_getenvlist by searching for known
266 * env vars (e.g. KRB5CCNAME) from the PAM environment.
267 */
268 return NULL;
269 }
270 #endif
271
272 #ifndef HAVE_PAM_PUTENV
273 static int
pam_putenv(pam_handle_t * pamh,const char * name_value)274 pam_putenv(pam_handle_t *pamh, const char *name_value)
275 {
276 return PAM_SUCCESS;
277 }
278 #endif /* HAVE_PAM_PUTENV */
279
280 /*
281 * Some platforms, notably Solaris, do not enforce password complexity
282 * rules during pam_chauthtok() if the real uid of the calling process
283 * is 0, on the assumption that it's being called by "passwd" run by root.
284 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
285 * the right thing.
286 */
287 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
288 static int
sshpam_chauthtok_ruid(pam_handle_t * pamh,int flags)289 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
290 {
291 int result;
292
293 if (sshpam_authctxt == NULL)
294 fatal("PAM: sshpam_authctxt not initialized");
295 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
296 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
297 result = pam_chauthtok(pamh, flags);
298 if (setreuid(0, -1) == -1)
299 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
300 return result;
301 }
302 # define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b)))
303 #endif
304
305 static void
sshpam_password_change_required(int reqd)306 sshpam_password_change_required(int reqd)
307 {
308 extern struct sshauthopt *auth_opts;
309 static int saved_port, saved_agent, saved_x11;
310
311 debug3("%s %d", __func__, reqd);
312 if (sshpam_authctxt == NULL)
313 fatal("%s: PAM authctxt not initialized", __func__);
314 sshpam_authctxt->force_pwchange = reqd;
315 if (reqd) {
316 saved_port = auth_opts->permit_port_forwarding_flag;
317 saved_agent = auth_opts->permit_agent_forwarding_flag;
318 saved_x11 = auth_opts->permit_x11_forwarding_flag;
319 auth_opts->permit_port_forwarding_flag = 0;
320 auth_opts->permit_agent_forwarding_flag = 0;
321 auth_opts->permit_x11_forwarding_flag = 0;
322 } else {
323 if (saved_port)
324 auth_opts->permit_port_forwarding_flag = saved_port;
325 if (saved_agent)
326 auth_opts->permit_agent_forwarding_flag = saved_agent;
327 if (saved_x11)
328 auth_opts->permit_x11_forwarding_flag = saved_x11;
329 }
330 }
331
332 /* Import regular and PAM environment from subprocess */
333 static void
import_environments(struct sshbuf * b)334 import_environments(struct sshbuf *b)
335 {
336 char *env;
337 u_int n, i, num_env;
338 int r;
339
340 debug3("PAM: %s entering", __func__);
341
342 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
343 /* Import variables set by do_pam_account */
344 if ((r = sshbuf_get_u32(b, &n)) != 0)
345 fatal("%s: buffer error: %s", __func__, ssh_err(r));
346 if (n > INT_MAX)
347 fatal("%s: invalid PAM account status %u", __func__, n);
348 sshpam_account_status = (int)n;
349 if ((r = sshbuf_get_u32(b, &n)) != 0)
350 fatal("%s: buffer error: %s", __func__, ssh_err(r));
351 sshpam_password_change_required(n != 0);
352
353 /* Import environment from subprocess */
354 if ((r = sshbuf_get_u32(b, &num_env)) != 0)
355 fatal("%s: buffer error: %s", __func__, ssh_err(r));
356 if (num_env > 1024)
357 fatal("%s: received %u environment variables, expected <= 1024",
358 __func__, num_env);
359 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env));
360 debug3("PAM: num env strings %d", num_env);
361 for(i = 0; i < num_env; i++) {
362 if ((r = sshbuf_get_cstring(b, &(sshpam_env[i]), NULL)) != 0)
363 fatal("%s: buffer error: %s", __func__, ssh_err(r));
364 }
365 sshpam_env[num_env] = NULL;
366
367 /* Import PAM environment from subprocess */
368 if ((r = sshbuf_get_u32(b, &num_env)) != 0)
369 fatal("%s: buffer error: %s", __func__, ssh_err(r));
370 debug("PAM: num PAM env strings %d", 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 || (use_privsep && !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
693 #if defined(PAM_SUN_CODEBASE) && defined(PAM_MAX_RESP_SIZE)
694 /* Protect buggy PAM implementations from excessively long usernames */
695 if (strlen(user) >= PAM_MAX_RESP_SIZE)
696 fatal("Username too long from %s port %d",
697 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
698 #endif
699 if (sshpam_handle == NULL) {
700 if (ssh == NULL) {
701 fatal("%s: called initially with no "
702 "packet context", __func__);
703 }
704 } if (sshpam_handle != NULL) {
705 /* We already have a PAM context; check if the user matches */
706 sshpam_err = pam_get_item(sshpam_handle,
707 PAM_USER, (sshpam_const void **)ptr_pam_user);
708 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
709 return (0);
710 pam_end(sshpam_handle, sshpam_err);
711 sshpam_handle = NULL;
712 }
713 debug("PAM: initializing for \"%s\"", user);
714 sshpam_err =
715 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
716 sshpam_authctxt = authctxt;
717
718 if (sshpam_err != PAM_SUCCESS) {
719 pam_end(sshpam_handle, sshpam_err);
720 sshpam_handle = NULL;
721 return (-1);
722 }
723
724 if (ssh != NULL && sshpam_rhost == NULL) {
725 /*
726 * We need to cache these as we don't have packet context
727 * during the kbdint flow.
728 */
729 sshpam_rhost = xstrdup(auth_get_canonical_hostname(ssh,
730 options.use_dns));
731 sshpam_laddr = get_local_ipaddr(
732 ssh_packet_get_connection_in(ssh));
733 xasprintf(&sshpam_conninfo, "SSH_CONNECTION=%.50s %d %.50s %d",
734 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
735 sshpam_laddr, ssh_local_port(ssh));
736 }
737 if (sshpam_rhost != NULL) {
738 debug("PAM: setting PAM_RHOST to \"%s\"", sshpam_rhost);
739 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST,
740 sshpam_rhost);
741 if (sshpam_err != PAM_SUCCESS) {
742 pam_end(sshpam_handle, sshpam_err);
743 sshpam_handle = NULL;
744 return (-1);
745 }
746 /* Put SSH_CONNECTION in the PAM environment too */
747 pam_putenv(sshpam_handle, sshpam_conninfo);
748 }
749
750 #ifdef PAM_TTY_KLUDGE
751 /*
752 * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
753 * sshd doesn't set the tty until too late in the auth process and
754 * may not even set one (for tty-less connections)
755 */
756 debug("PAM: setting PAM_TTY to \"ssh\"");
757 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
758 if (sshpam_err != PAM_SUCCESS) {
759 pam_end(sshpam_handle, sshpam_err);
760 sshpam_handle = NULL;
761 return (-1);
762 }
763 #endif
764 return (0);
765 }
766
767 static void
expose_authinfo(const char * caller)768 expose_authinfo(const char *caller)
769 {
770 char *auth_info;
771
772 /*
773 * Expose authentication information to PAM.
774 * The environment variable is versioned. Please increment the
775 * version suffix if the format of session_info changes.
776 */
777 if (sshpam_authctxt->session_info == NULL)
778 auth_info = xstrdup("");
779 else if ((auth_info = sshbuf_dup_string(
780 sshpam_authctxt->session_info)) == NULL)
781 fatal("%s: sshbuf_dup_string failed", __func__);
782
783 debug2("%s: auth information in SSH_AUTH_INFO_0", caller);
784 do_pam_putenv("SSH_AUTH_INFO_0", auth_info);
785 free(auth_info);
786 }
787
788 static void *
sshpam_init_ctx(Authctxt * authctxt)789 sshpam_init_ctx(Authctxt *authctxt)
790 {
791 struct pam_ctxt *ctxt;
792 int result, socks[2];
793
794 debug3("PAM: %s entering", __func__);
795 /*
796 * Refuse to start if we don't have PAM enabled or do_pam_account
797 * has previously failed.
798 */
799 if (!options.use_pam || sshpam_account_status == 0)
800 return NULL;
801
802 /* Initialize PAM */
803 if (sshpam_init(NULL, authctxt) == -1) {
804 error("PAM: initialization failed");
805 return (NULL);
806 }
807
808 expose_authinfo(__func__);
809 ctxt = xcalloc(1, sizeof *ctxt);
810
811 /* Start the authentication thread */
812 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
813 error("PAM: failed create sockets: %s", strerror(errno));
814 free(ctxt);
815 return (NULL);
816 }
817 ctxt->pam_psock = socks[0];
818 ctxt->pam_csock = socks[1];
819 result = pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt);
820 if (result != 0) {
821 error("PAM: failed to start authentication thread: %s",
822 strerror(result));
823 close(socks[0]);
824 close(socks[1]);
825 free(ctxt);
826 return (NULL);
827 }
828 cleanup_ctxt = ctxt;
829 return (ctxt);
830 }
831
832 static int
sshpam_query(void * ctx,char ** name,char ** info,u_int * num,char *** prompts,u_int ** echo_on)833 sshpam_query(void *ctx, char **name, char **info,
834 u_int *num, char ***prompts, u_int **echo_on)
835 {
836 struct sshbuf *buffer;
837 struct pam_ctxt *ctxt = ctx;
838 size_t plen;
839 u_char type;
840 char *msg;
841 size_t len, mlen;
842 int r;
843
844 debug3("PAM: %s entering", __func__);
845 if ((buffer = sshbuf_new()) == NULL)
846 fatal("%s: sshbuf_new failed", __func__);
847 *name = xstrdup("");
848 *info = xstrdup("");
849 *prompts = xmalloc(sizeof(char *));
850 **prompts = NULL;
851 plen = 0;
852 *echo_on = xmalloc(sizeof(u_int));
853 while (ssh_msg_recv(ctxt->pam_psock, buffer) == 0) {
854 if ((r = sshbuf_get_u8(buffer, &type)) != 0 ||
855 (r = sshbuf_get_cstring(buffer, &msg, &mlen)) != 0)
856 fatal("%s: buffer error: %s", __func__, ssh_err(r));
857 switch (type) {
858 case PAM_PROMPT_ECHO_ON:
859 case PAM_PROMPT_ECHO_OFF:
860 *num = 1;
861 len = plen + mlen + 1;
862 **prompts = xreallocarray(**prompts, 1, len);
863 strlcpy(**prompts + plen, msg, len - plen);
864 plen += mlen;
865 **echo_on = (type == PAM_PROMPT_ECHO_ON);
866 free(msg);
867 sshbuf_free(buffer);
868 return (0);
869 case PAM_ERROR_MSG:
870 case PAM_TEXT_INFO:
871 /* accumulate messages */
872 len = plen + mlen + 2;
873 **prompts = xreallocarray(**prompts, 1, len);
874 strlcpy(**prompts + plen, msg, len - plen);
875 plen += mlen;
876 strlcat(**prompts + plen, "\n", len - plen);
877 plen++;
878 free(msg);
879 break;
880 case PAM_ACCT_EXPIRED:
881 case PAM_MAXTRIES:
882 if (type == PAM_ACCT_EXPIRED)
883 sshpam_account_status = 0;
884 if (type == PAM_MAXTRIES)
885 sshpam_set_maxtries_reached(1);
886 /* FALLTHROUGH */
887 case PAM_AUTH_ERR:
888 debug3("PAM: %s", pam_strerror(sshpam_handle, type));
889 if (**prompts != NULL && strlen(**prompts) != 0) {
890 free(*info);
891 *info = **prompts;
892 **prompts = NULL;
893 *num = 0;
894 **echo_on = 0;
895 ctxt->pam_done = -1;
896 free(msg);
897 sshbuf_free(buffer);
898 return 0;
899 }
900 /* FALLTHROUGH */
901 case PAM_SUCCESS:
902 if (**prompts != NULL) {
903 /* drain any accumulated messages */
904 debug("PAM: %s", **prompts);
905 if ((r = sshbuf_put(loginmsg, **prompts,
906 strlen(**prompts))) != 0)
907 fatal("%s: buffer error: %s",
908 __func__, ssh_err(r));
909 free(**prompts);
910 **prompts = NULL;
911 }
912 if (type == PAM_SUCCESS) {
913 if (!sshpam_authctxt->valid ||
914 (sshpam_authctxt->pw->pw_uid == 0 &&
915 options.permit_root_login != PERMIT_YES))
916 fatal("Internal error: PAM auth "
917 "succeeded when it should have "
918 "failed");
919 import_environments(buffer);
920 *num = 0;
921 **echo_on = 0;
922 ctxt->pam_done = 1;
923 free(msg);
924 sshbuf_free(buffer);
925 return (0);
926 }
927 BLACKLIST_NOTIFY(NULL, BLACKLIST_BAD_USER,
928 sshpam_authctxt->user);
929 error("PAM: %s for %s%.100s from %.100s", msg,
930 sshpam_authctxt->valid ? "" : "illegal user ",
931 sshpam_authctxt->user, sshpam_rhost);
932 /* FALLTHROUGH */
933 default:
934 *num = 0;
935 **echo_on = 0;
936 free(msg);
937 ctxt->pam_done = -1;
938 sshbuf_free(buffer);
939 return (-1);
940 }
941 }
942 sshbuf_free(buffer);
943 return (-1);
944 }
945
946 /*
947 * Returns a junk password of identical length to that the user supplied.
948 * Used to mitigate timing attacks against crypt(3)/PAM stacks that
949 * vary processing time in proportion to password length.
950 */
951 static char *
fake_password(const char * wire_password)952 fake_password(const char *wire_password)
953 {
954 const char junk[] = "\b\n\r\177INCORRECT";
955 char *ret = NULL;
956 size_t i, l = wire_password != NULL ? strlen(wire_password) : 0;
957
958 if (l >= INT_MAX)
959 fatal("%s: password length too long: %zu", __func__, l);
960
961 ret = malloc(l + 1);
962 if (ret == NULL)
963 return NULL;
964 for (i = 0; i < l; i++)
965 ret[i] = junk[i % (sizeof(junk) - 1)];
966 ret[i] = '\0';
967 return ret;
968 }
969
970 /* XXX - see also comment in auth-chall.c:verify_response */
971 static int
sshpam_respond(void * ctx,u_int num,char ** resp)972 sshpam_respond(void *ctx, u_int num, char **resp)
973 {
974 struct sshbuf *buffer;
975 struct pam_ctxt *ctxt = ctx;
976 char *fake;
977 int r;
978
979 debug2("PAM: %s entering, %u responses", __func__, num);
980 switch (ctxt->pam_done) {
981 case 1:
982 sshpam_authenticated = 1;
983 return (0);
984 case 0:
985 break;
986 default:
987 return (-1);
988 }
989 if (num != 1) {
990 error("PAM: expected one response, got %u", num);
991 return (-1);
992 }
993 if ((buffer = sshbuf_new()) == NULL)
994 fatal("%s: sshbuf_new failed", __func__);
995 if (sshpam_authctxt->valid &&
996 (sshpam_authctxt->pw->pw_uid != 0 ||
997 options.permit_root_login == PERMIT_YES)) {
998 if ((r = sshbuf_put_cstring(buffer, *resp)) != 0)
999 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1000 } else {
1001 fake = fake_password(*resp);
1002 if ((r = sshbuf_put_cstring(buffer, fake)) != 0)
1003 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1004 free(fake);
1005 }
1006 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, buffer) == -1) {
1007 sshbuf_free(buffer);
1008 return (-1);
1009 }
1010 sshbuf_free(buffer);
1011 return (1);
1012 }
1013
1014 static void
sshpam_free_ctx(void * ctxtp)1015 sshpam_free_ctx(void *ctxtp)
1016 {
1017 struct pam_ctxt *ctxt = ctxtp;
1018
1019 debug3("PAM: %s entering", __func__);
1020 sshpam_thread_cleanup();
1021 free(ctxt);
1022 /*
1023 * We don't call sshpam_cleanup() here because we may need the PAM
1024 * handle at a later stage, e.g. when setting up a session. It's
1025 * still on the cleanup list, so pam_end() *will* be called before
1026 * the server process terminates.
1027 */
1028 }
1029
1030 KbdintDevice sshpam_device = {
1031 "pam",
1032 sshpam_init_ctx,
1033 sshpam_query,
1034 sshpam_respond,
1035 sshpam_free_ctx
1036 };
1037
1038 KbdintDevice mm_sshpam_device = {
1039 "pam",
1040 mm_sshpam_init_ctx,
1041 mm_sshpam_query,
1042 mm_sshpam_respond,
1043 mm_sshpam_free_ctx
1044 };
1045
1046 /*
1047 * This replaces auth-pam.c
1048 */
1049 void
start_pam(struct ssh * ssh)1050 start_pam(struct ssh *ssh)
1051 {
1052 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1053
1054 if (!options.use_pam)
1055 fatal("PAM: initialisation requested when UsePAM=no");
1056
1057 if (sshpam_init(ssh, authctxt) == -1)
1058 fatal("PAM: initialisation failed");
1059 }
1060
1061 void
finish_pam(void)1062 finish_pam(void)
1063 {
1064 sshpam_cleanup();
1065 }
1066
1067
1068 u_int
do_pam_account(void)1069 do_pam_account(void)
1070 {
1071 debug("%s: called", __func__);
1072 if (sshpam_account_status != -1)
1073 return (sshpam_account_status);
1074
1075 expose_authinfo(__func__);
1076
1077 sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
1078 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
1079 pam_strerror(sshpam_handle, sshpam_err));
1080
1081 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
1082 sshpam_account_status = 0;
1083 return (sshpam_account_status);
1084 }
1085
1086 if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
1087 sshpam_password_change_required(1);
1088
1089 sshpam_account_status = 1;
1090 return (sshpam_account_status);
1091 }
1092
1093 void
do_pam_setcred(int init)1094 do_pam_setcred(int init)
1095 {
1096 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1097 (const void *)&store_conv);
1098 if (sshpam_err != PAM_SUCCESS)
1099 fatal("PAM: failed to set PAM_CONV: %s",
1100 pam_strerror(sshpam_handle, sshpam_err));
1101 if (init) {
1102 debug("PAM: establishing credentials");
1103 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
1104 } else {
1105 debug("PAM: reinitializing credentials");
1106 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
1107 }
1108 if (sshpam_err == PAM_SUCCESS) {
1109 sshpam_cred_established = 1;
1110 return;
1111 }
1112 if (sshpam_authenticated)
1113 fatal("PAM: pam_setcred(): %s",
1114 pam_strerror(sshpam_handle, sshpam_err));
1115 else
1116 debug("PAM: pam_setcred(): %s",
1117 pam_strerror(sshpam_handle, sshpam_err));
1118 }
1119
1120 static int
sshpam_tty_conv(int n,sshpam_const struct pam_message ** msg,struct pam_response ** resp,void * data)1121 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
1122 struct pam_response **resp, void *data)
1123 {
1124 char input[PAM_MAX_MSG_SIZE];
1125 struct pam_response *reply;
1126 int i;
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 || !isatty(STDIN_FILENO))
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 reply[i].resp =
1142 read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
1143 RP_ALLOW_STDIN);
1144 reply[i].resp_retcode = PAM_SUCCESS;
1145 break;
1146 case PAM_PROMPT_ECHO_ON:
1147 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1148 if (fgets(input, sizeof input, stdin) == NULL)
1149 input[0] = '\0';
1150 if ((reply[i].resp = strdup(input)) == NULL)
1151 goto fail;
1152 reply[i].resp_retcode = PAM_SUCCESS;
1153 break;
1154 case PAM_ERROR_MSG:
1155 case PAM_TEXT_INFO:
1156 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
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 free(reply[i].resp);
1169 }
1170 free(reply);
1171 return (PAM_CONV_ERR);
1172 }
1173
1174 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
1175
1176 /*
1177 * XXX this should be done in the authentication phase, but ssh1 doesn't
1178 * support that
1179 */
1180 void
do_pam_chauthtok(void)1181 do_pam_chauthtok(void)
1182 {
1183 if (use_privsep)
1184 fatal("Password expired (unable to change with privsep)");
1185 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1186 (const void *)&tty_conv);
1187 if (sshpam_err != PAM_SUCCESS)
1188 fatal("PAM: failed to set PAM_CONV: %s",
1189 pam_strerror(sshpam_handle, sshpam_err));
1190 debug("PAM: changing password");
1191 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
1192 if (sshpam_err != PAM_SUCCESS)
1193 fatal("PAM: pam_chauthtok(): %s",
1194 pam_strerror(sshpam_handle, sshpam_err));
1195 }
1196
1197 void
do_pam_session(struct ssh * ssh)1198 do_pam_session(struct ssh *ssh)
1199 {
1200 debug3("PAM: opening session");
1201
1202 expose_authinfo(__func__);
1203
1204 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1205 (const void *)&store_conv);
1206 if (sshpam_err != PAM_SUCCESS)
1207 fatal("PAM: failed to set PAM_CONV: %s",
1208 pam_strerror(sshpam_handle, sshpam_err));
1209 sshpam_err = pam_open_session(sshpam_handle, 0);
1210 if (sshpam_err == PAM_SUCCESS)
1211 sshpam_session_open = 1;
1212 else {
1213 sshpam_session_open = 0;
1214 auth_restrict_session(ssh);
1215 error("PAM: pam_open_session(): %s",
1216 pam_strerror(sshpam_handle, sshpam_err));
1217 }
1218
1219 }
1220
1221 int
is_pam_session_open(void)1222 is_pam_session_open(void)
1223 {
1224 return sshpam_session_open;
1225 }
1226
1227 /*
1228 * Set a PAM environment string. We need to do this so that the session
1229 * modules can handle things like Kerberos/GSI credentials that appear
1230 * during the ssh authentication process.
1231 */
1232 int
do_pam_putenv(char * name,char * value)1233 do_pam_putenv(char *name, char *value)
1234 {
1235 int ret = 1;
1236 char *compound;
1237 size_t len;
1238
1239 len = strlen(name) + strlen(value) + 2;
1240 compound = xmalloc(len);
1241
1242 snprintf(compound, len, "%s=%s", name, value);
1243 ret = pam_putenv(sshpam_handle, compound);
1244 free(compound);
1245
1246 return (ret);
1247 }
1248
1249 char **
fetch_pam_child_environment(void)1250 fetch_pam_child_environment(void)
1251 {
1252 return sshpam_env;
1253 }
1254
1255 char **
fetch_pam_environment(void)1256 fetch_pam_environment(void)
1257 {
1258 return (pam_getenvlist(sshpam_handle));
1259 }
1260
1261 void
free_pam_environment(char ** env)1262 free_pam_environment(char **env)
1263 {
1264 char **envp;
1265
1266 if (env == NULL)
1267 return;
1268
1269 for (envp = env; *envp; envp++)
1270 free(*envp);
1271 free(env);
1272 }
1273
1274 /*
1275 * "Blind" conversation function for password authentication. Assumes that
1276 * echo-off prompts are for the password and stores messages for later
1277 * display.
1278 */
1279 static int
sshpam_passwd_conv(int n,sshpam_const struct pam_message ** msg,struct pam_response ** resp,void * data)1280 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1281 struct pam_response **resp, void *data)
1282 {
1283 struct pam_response *reply;
1284 int r, i;
1285 size_t len;
1286
1287 debug3("PAM: %s called with %d messages", __func__, n);
1288
1289 *resp = NULL;
1290
1291 if (n <= 0 || n > PAM_MAX_NUM_MSG)
1292 return (PAM_CONV_ERR);
1293
1294 if ((reply = calloc(n, sizeof(*reply))) == NULL)
1295 return (PAM_CONV_ERR);
1296
1297 for (i = 0; i < n; ++i) {
1298 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1299 case PAM_PROMPT_ECHO_OFF:
1300 if (sshpam_password == NULL)
1301 goto fail;
1302 if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1303 goto fail;
1304 reply[i].resp_retcode = PAM_SUCCESS;
1305 break;
1306 case PAM_ERROR_MSG:
1307 case PAM_TEXT_INFO:
1308 len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1309 if (len > 0) {
1310 if ((r = sshbuf_putf(loginmsg, "%s\n",
1311 PAM_MSG_MEMBER(msg, i, msg))) != 0)
1312 fatal("%s: buffer error: %s",
1313 __func__, ssh_err(r));
1314 }
1315 if ((reply[i].resp = strdup("")) == NULL)
1316 goto fail;
1317 reply[i].resp_retcode = PAM_SUCCESS;
1318 break;
1319 default:
1320 goto fail;
1321 }
1322 }
1323 *resp = reply;
1324 return (PAM_SUCCESS);
1325
1326 fail:
1327 for(i = 0; i < n; i++) {
1328 free(reply[i].resp);
1329 }
1330 free(reply);
1331 return (PAM_CONV_ERR);
1332 }
1333
1334 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1335
1336 /*
1337 * Attempt password authentication via PAM
1338 */
1339 int
sshpam_auth_passwd(Authctxt * authctxt,const char * password)1340 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1341 {
1342 int flags = (options.permit_empty_passwd == 0 ?
1343 PAM_DISALLOW_NULL_AUTHTOK : 0);
1344 char *fake = NULL;
1345
1346 if (!options.use_pam || sshpam_handle == NULL)
1347 fatal("PAM: %s called when PAM disabled or failed to "
1348 "initialise.", __func__);
1349
1350 sshpam_password = password;
1351 sshpam_authctxt = authctxt;
1352
1353 /*
1354 * If the user logging in is invalid, or is root but is not permitted
1355 * by PermitRootLogin, use an invalid password to prevent leaking
1356 * information via timing (eg if the PAM config has a delay on fail).
1357 */
1358 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1359 options.permit_root_login != PERMIT_YES))
1360 sshpam_password = fake = fake_password(password);
1361
1362 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1363 (const void *)&passwd_conv);
1364 if (sshpam_err != PAM_SUCCESS)
1365 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1366 pam_strerror(sshpam_handle, sshpam_err));
1367
1368 sshpam_err = pam_authenticate(sshpam_handle, flags);
1369 sshpam_password = NULL;
1370 free(fake);
1371 if (sshpam_err == PAM_MAXTRIES)
1372 sshpam_set_maxtries_reached(1);
1373 if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1374 debug("PAM: password authentication accepted for %.100s",
1375 authctxt->user);
1376 return 1;
1377 } else {
1378 debug("PAM: password authentication failed for %.100s: %s",
1379 authctxt->valid ? authctxt->user : "an illegal user",
1380 pam_strerror(sshpam_handle, sshpam_err));
1381 return 0;
1382 }
1383 }
1384
1385 int
sshpam_get_maxtries_reached(void)1386 sshpam_get_maxtries_reached(void)
1387 {
1388 return sshpam_maxtries_reached;
1389 }
1390
1391 void
sshpam_set_maxtries_reached(int reached)1392 sshpam_set_maxtries_reached(int reached)
1393 {
1394 if (reached == 0 || sshpam_maxtries_reached)
1395 return;
1396 sshpam_maxtries_reached = 1;
1397 options.password_authentication = 0;
1398 options.kbd_interactive_authentication = 0;
1399 }
1400 #endif /* USE_PAM */
1401