2 * Copyright (c) 2002 Networks Associates Technology, Inc.
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.
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
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.
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
32 * Copyright (c) 2003,2004 Damien Miller <djm@mindrot.org>
33 * Copyright (c) 2003,2004 Darren Tucker <dtucker@zip.com.au>
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.
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.
48 /* Based on FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des */
52 #include <sys/types.h>
63 #if defined(HAVE_SECURITY_PAM_APPL_H)
64 #include <security/pam_appl.h>
65 #elif defined (HAVE_PAM_PAM_APPL_H)
66 #include <pam/pam_appl.h>
69 #if !defined(SSHD_PAM_SERVICE)
70 extern char *__progname;
71 # define SSHD_PAM_SERVICE __progname
74 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */
75 #ifdef PAM_SUN_CODEBASE
76 # define sshpam_const /* Solaris, HP-UX, SunOS */
78 # define sshpam_const const /* LinuxPAM, OpenPAM, AIX */
81 /* Ambiguity in spec: is it an array of pointers or a pointer to an array? */
82 #ifdef PAM_SUN_CODEBASE
83 # define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member)
85 # define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member)
101 #include "auth-options.h"
105 #include "monitor_wrap.h"
106 #include "blacklist_client.h"
108 extern ServerOptions options;
109 extern struct sshbuf *loginmsg;
110 extern u_int utmp_len;
112 /* so we don't silently change behaviour */
113 #ifdef USE_POSIX_THREADS
114 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
118 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
119 * and generally a bad idea. Use at own risk and do not expect support if
122 #ifdef UNSUPPORTED_POSIX_THREADS_HACK
125 * Avoid namespace clash when *not* using pthreads for systems *with*
126 * pthreads, which unconditionally define pthread_t via sys/types.h
129 typedef pthread_t sp_pthread_t;
131 typedef pid_t sp_pthread_t;
132 #define pthread_exit fake_pthread_exit
133 #define pthread_create fake_pthread_create
134 #define pthread_cancel fake_pthread_cancel
135 #define pthread_join fake_pthread_join
139 sp_pthread_t pam_thread;
145 static void sshpam_free_ctx(void *);
146 static struct pam_ctxt *cleanup_ctxt;
148 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
150 * Simulate threads with processes.
153 static int sshpam_thread_status = -1;
154 static mysig_t sshpam_oldsig;
157 sshpam_sigchld_handler(int sig)
159 signal(SIGCHLD, SIG_DFL);
160 if (cleanup_ctxt == NULL)
161 return; /* handler called after PAM cleanup, shouldn't happen */
162 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
164 /* PAM thread has not exitted, privsep slave must have */
165 kill(cleanup_ctxt->pam_thread, SIGTERM);
166 while (waitpid(cleanup_ctxt->pam_thread,
167 &sshpam_thread_status, 0) == -1) {
173 if (WIFSIGNALED(sshpam_thread_status) &&
174 WTERMSIG(sshpam_thread_status) == SIGTERM)
175 return; /* terminated by pthread_cancel */
176 if (!WIFEXITED(sshpam_thread_status))
177 sigdie("PAM: authentication thread exited unexpectedly");
178 if (WEXITSTATUS(sshpam_thread_status) != 0)
179 sigdie("PAM: authentication thread exited uncleanly");
184 pthread_exit(void *value)
191 pthread_create(sp_pthread_t *thread, const void *attr,
192 void *(*thread_start)(void *), void *arg)
195 struct pam_ctxt *ctx = arg;
197 sshpam_thread_status = -1;
198 switch ((pid = fork())) {
200 error("fork(): %s", strerror(errno));
203 close(ctx->pam_psock);
209 close(ctx->pam_csock);
211 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
217 pthread_cancel(sp_pthread_t thread)
219 signal(SIGCHLD, sshpam_oldsig);
220 return (kill(thread, SIGTERM));
225 pthread_join(sp_pthread_t thread, void **value)
229 if (sshpam_thread_status != -1)
230 return (sshpam_thread_status);
231 signal(SIGCHLD, sshpam_oldsig);
232 while (waitpid(thread, &status, 0) == -1) {
235 fatal("%s: waitpid: %s", __func__, strerror(errno));
242 static pam_handle_t *sshpam_handle = NULL;
243 static int sshpam_err = 0;
244 static int sshpam_authenticated = 0;
245 static int sshpam_session_open = 0;
246 static int sshpam_cred_established = 0;
247 static int sshpam_account_status = -1;
248 static int sshpam_maxtries_reached = 0;
249 static char **sshpam_env = NULL;
250 static Authctxt *sshpam_authctxt = NULL;
251 static const char *sshpam_password = NULL;
253 /* Some PAM implementations don't implement this */
254 #ifndef HAVE_PAM_GETENVLIST
256 pam_getenvlist(pam_handle_t *pamh)
259 * XXX - If necessary, we can still support envrionment passing
260 * for platforms without pam_getenvlist by searching for known
261 * env vars (e.g. KRB5CCNAME) from the PAM environment.
268 * Some platforms, notably Solaris, do not enforce password complexity
269 * rules during pam_chauthtok() if the real uid of the calling process
270 * is 0, on the assumption that it's being called by "passwd" run by root.
271 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
274 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
276 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
280 if (sshpam_authctxt == NULL)
281 fatal("PAM: sshpam_authctxt not initialized");
282 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
283 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
284 result = pam_chauthtok(pamh, flags);
285 if (setreuid(0, -1) == -1)
286 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
289 # define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b)))
293 sshpam_password_change_required(int reqd)
295 extern struct sshauthopt *auth_opts;
296 static int saved_port, saved_agent, saved_x11;
298 debug3("%s %d", __func__, reqd);
299 if (sshpam_authctxt == NULL)
300 fatal("%s: PAM authctxt not initialized", __func__);
301 sshpam_authctxt->force_pwchange = reqd;
303 saved_port = auth_opts->permit_port_forwarding_flag;
304 saved_agent = auth_opts->permit_agent_forwarding_flag;
305 saved_x11 = auth_opts->permit_x11_forwarding_flag;
306 auth_opts->permit_port_forwarding_flag = 0;
307 auth_opts->permit_agent_forwarding_flag = 0;
308 auth_opts->permit_x11_forwarding_flag = 0;
311 auth_opts->permit_port_forwarding_flag = saved_port;
313 auth_opts->permit_agent_forwarding_flag = saved_agent;
315 auth_opts->permit_x11_forwarding_flag = saved_x11;
319 /* Import regular and PAM environment from subprocess */
321 import_environments(struct sshbuf *b)
327 debug3("PAM: %s entering", __func__);
329 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
330 /* Import variables set by do_pam_account */
331 if ((r = sshbuf_get_u32(b, &n)) != 0)
332 fatal("%s: buffer error: %s", __func__, ssh_err(r));
334 fatal("%s: invalid PAM account status %u", __func__, n);
335 sshpam_account_status = (int)n;
336 if ((r = sshbuf_get_u32(b, &n)) != 0)
337 fatal("%s: buffer error: %s", __func__, ssh_err(r));
338 sshpam_password_change_required(n != 0);
340 /* Import environment from subprocess */
341 if ((r = sshbuf_get_u32(b, &num_env)) != 0)
342 fatal("%s: buffer error: %s", __func__, ssh_err(r));
344 fatal("%s: received %u environment variables, expected <= 1024",
346 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env));
347 debug3("PAM: num env strings %d", num_env);
348 for(i = 0; i < num_env; i++) {
349 if ((r = sshbuf_get_cstring(b, &(sshpam_env[i]), NULL)) != 0)
350 fatal("%s: buffer error: %s", __func__, ssh_err(r));
352 sshpam_env[num_env] = NULL;
354 /* Import PAM environment from subprocess */
355 if ((r = sshbuf_get_u32(b, &num_env)) != 0)
356 fatal("%s: buffer error: %s", __func__, ssh_err(r));
357 debug("PAM: num PAM env strings %d", num_env);
358 for (i = 0; i < num_env; i++) {
359 if ((r = sshbuf_get_cstring(b, &env, NULL)) != 0)
360 fatal("%s: buffer error: %s", __func__, ssh_err(r));
361 #ifdef HAVE_PAM_PUTENV
362 /* Errors are not fatal here */
363 if ((r = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
364 error("PAM: pam_putenv: %s",
365 pam_strerror(sshpam_handle, r));
374 * Conversation function for authentication thread.
377 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
378 struct pam_response **resp, void *data)
380 struct sshbuf *buffer;
381 struct pam_ctxt *ctxt;
382 struct pam_response *reply;
386 debug3("PAM: %s entering, %d messages", __func__, n);
390 error("PAM: conversation function passed a null context");
391 return (PAM_CONV_ERR);
394 if (n <= 0 || n > PAM_MAX_NUM_MSG)
395 return (PAM_CONV_ERR);
397 if ((reply = calloc(n, sizeof(*reply))) == NULL)
399 if ((buffer = sshbuf_new()) == NULL) {
404 for (i = 0; i < n; ++i) {
405 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
406 case PAM_PROMPT_ECHO_OFF:
407 case PAM_PROMPT_ECHO_ON:
408 if ((r = sshbuf_put_cstring(buffer,
409 PAM_MSG_MEMBER(msg, i, msg))) != 0)
410 fatal("%s: buffer error: %s",
411 __func__, ssh_err(r));
412 if (ssh_msg_send(ctxt->pam_csock,
413 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1)
416 if (ssh_msg_recv(ctxt->pam_csock, buffer) == -1)
418 if ((r = sshbuf_get_u8(buffer, &status)) != 0)
419 fatal("%s: buffer error: %s",
420 __func__, ssh_err(r));
421 if (status != PAM_AUTHTOK)
423 if ((r = sshbuf_get_cstring(buffer,
424 &reply[i].resp, NULL)) != 0)
425 fatal("%s: buffer error: %s",
426 __func__, ssh_err(r));
430 if ((r = sshbuf_put_cstring(buffer,
431 PAM_MSG_MEMBER(msg, i, msg))) != 0)
432 fatal("%s: buffer error: %s",
433 __func__, ssh_err(r));
434 if (ssh_msg_send(ctxt->pam_csock,
435 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1)
441 sshbuf_reset(buffer);
445 return (PAM_SUCCESS);
448 for(i = 0; i < n; i++) {
453 return (PAM_CONV_ERR);
457 * Authentication thread.
460 sshpam_thread(void *ctxtp)
462 struct pam_ctxt *ctxt = ctxtp;
463 struct sshbuf *buffer = NULL;
464 struct pam_conv sshpam_conv;
465 int r, flags = (options.permit_empty_passwd == 0 ?
466 PAM_DISALLOW_NULL_AUTHTOK : 0);
467 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
468 extern char **environ;
471 const char *pam_user;
472 const char **ptr_pam_user = &pam_user;
473 char *tz = getenv("TZ");
475 sshpam_err = pam_get_item(sshpam_handle, PAM_USER,
476 (sshpam_const void **)ptr_pam_user);
477 if (sshpam_err != PAM_SUCCESS)
482 if (setenv("TZ", tz, 1) == -1)
483 error("PAM: could not set TZ environment: %s",
486 if (sshpam_authctxt != NULL) {
487 setproctitle("%s [pam]",
488 sshpam_authctxt->valid ? pam_user : "unknown");
492 sshpam_conv.conv = sshpam_thread_conv;
493 sshpam_conv.appdata_ptr = ctxt;
495 if (sshpam_authctxt == NULL)
496 fatal("%s: PAM authctxt not initialized", __func__);
498 if ((buffer = sshbuf_new()) == NULL)
499 fatal("%s: sshbuf_new failed", __func__);
501 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
502 (const void *)&sshpam_conv);
503 if (sshpam_err != PAM_SUCCESS)
505 sshpam_err = pam_authenticate(sshpam_handle, flags);
506 if (sshpam_err == PAM_MAXTRIES)
507 sshpam_set_maxtries_reached(1);
508 if (sshpam_err != PAM_SUCCESS)
511 if (!do_pam_account()) {
512 sshpam_err = PAM_ACCT_EXPIRED;
515 if (sshpam_authctxt->force_pwchange) {
516 sshpam_err = pam_chauthtok(sshpam_handle,
517 PAM_CHANGE_EXPIRED_AUTHTOK);
518 if (sshpam_err != PAM_SUCCESS)
520 sshpam_password_change_required(0);
523 if ((r = sshbuf_put_cstring(buffer, "OK")) != 0)
524 fatal("%s: buffer error: %s", __func__, ssh_err(r));
526 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
527 /* Export variables set by do_pam_account */
528 if ((r = sshbuf_put_u32(buffer, sshpam_account_status)) != 0 ||
529 (r = sshbuf_put_u32(buffer, sshpam_authctxt->force_pwchange)) != 0)
530 fatal("%s: buffer error: %s", __func__, ssh_err(r));
532 /* Export any environment strings set in child */
533 for (i = 0; environ[i] != NULL; i++) {
536 fatal("%s: too many enviornment strings", __func__);
538 if ((r = sshbuf_put_u32(buffer, i)) != 0)
539 fatal("%s: buffer error: %s", __func__, ssh_err(r));
540 for (i = 0; environ[i] != NULL; i++) {
541 if ((r = sshbuf_put_cstring(buffer, environ[i])) != 0)
542 fatal("%s: buffer error: %s", __func__, ssh_err(r));
544 /* Export any environment strings set by PAM in child */
545 env_from_pam = pam_getenvlist(sshpam_handle);
546 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) {
549 fatal("%s: too many PAM enviornment strings", __func__);
551 if ((r = sshbuf_put_u32(buffer, i)) != 0)
552 fatal("%s: buffer error: %s", __func__, ssh_err(r));
553 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) {
554 if ((r = sshbuf_put_cstring(buffer, env_from_pam[i])) != 0)
555 fatal("%s: buffer error: %s", __func__, ssh_err(r));
557 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */
559 /* XXX - can't do much about an error here */
560 ssh_msg_send(ctxt->pam_csock, sshpam_err, buffer);
565 if ((r = sshbuf_put_cstring(buffer,
566 pam_strerror(sshpam_handle, sshpam_err))) != 0)
567 fatal("%s: buffer error: %s", __func__, ssh_err(r));
568 /* XXX - can't do much about an error here */
569 if (sshpam_err == PAM_ACCT_EXPIRED)
570 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, buffer);
571 else if (sshpam_maxtries_reached)
572 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, buffer);
574 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, buffer);
578 return (NULL); /* Avoid warning for non-pthread case */
582 sshpam_thread_cleanup(void)
584 struct pam_ctxt *ctxt = cleanup_ctxt;
586 debug3("PAM: %s entering", __func__);
587 if (ctxt != NULL && ctxt->pam_thread != 0) {
588 pthread_cancel(ctxt->pam_thread);
589 pthread_join(ctxt->pam_thread, NULL);
590 close(ctxt->pam_psock);
591 close(ctxt->pam_csock);
592 memset(ctxt, 0, sizeof(*ctxt));
598 sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
599 struct pam_response **resp, void *data)
601 debug3("PAM: %s entering, %d messages", __func__, n);
602 return (PAM_CONV_ERR);
605 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
608 sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
609 struct pam_response **resp, void *data)
611 struct pam_response *reply;
614 debug3("PAM: %s called with %d messages", __func__, n);
617 if (n <= 0 || n > PAM_MAX_NUM_MSG)
618 return (PAM_CONV_ERR);
620 if ((reply = calloc(n, sizeof(*reply))) == NULL)
621 return (PAM_CONV_ERR);
623 for (i = 0; i < n; ++i) {
624 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
627 if ((r = sshbuf_putf(loginmsg, "%s\n",
628 PAM_MSG_MEMBER(msg, i, msg))) != 0)
629 fatal("%s: buffer error: %s",
630 __func__, ssh_err(r));
631 reply[i].resp_retcode = PAM_SUCCESS;
638 return (PAM_SUCCESS);
641 for(i = 0; i < n; i++) {
645 return (PAM_CONV_ERR);
648 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
653 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor()))
655 debug("PAM: cleanup");
656 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
657 if (sshpam_session_open) {
658 debug("PAM: closing session");
659 pam_close_session(sshpam_handle, PAM_SILENT);
660 sshpam_session_open = 0;
662 if (sshpam_cred_established) {
663 debug("PAM: deleting credentials");
664 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
665 sshpam_cred_established = 0;
667 sshpam_authenticated = 0;
668 pam_end(sshpam_handle, sshpam_err);
669 sshpam_handle = NULL;
673 sshpam_init(Authctxt *authctxt)
675 const char *pam_rhost, *pam_user, *user = authctxt->user;
676 const char **ptr_pam_user = &pam_user;
677 struct ssh *ssh = active_state; /* XXX */
679 if (sshpam_handle != NULL) {
680 /* We already have a PAM context; check if the user matches */
681 sshpam_err = pam_get_item(sshpam_handle,
682 PAM_USER, (sshpam_const void **)ptr_pam_user);
683 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
685 pam_end(sshpam_handle, sshpam_err);
686 sshpam_handle = NULL;
688 debug("PAM: initializing for \"%s\"", user);
690 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
691 sshpam_authctxt = authctxt;
693 if (sshpam_err != PAM_SUCCESS) {
694 pam_end(sshpam_handle, sshpam_err);
695 sshpam_handle = NULL;
698 pam_rhost = auth_get_canonical_hostname(ssh, options.use_dns);
699 debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
700 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
701 if (sshpam_err != PAM_SUCCESS) {
702 pam_end(sshpam_handle, sshpam_err);
703 sshpam_handle = NULL;
706 #ifdef PAM_TTY_KLUDGE
708 * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
709 * sshd doesn't set the tty until too late in the auth process and
710 * may not even set one (for tty-less connections)
712 debug("PAM: setting PAM_TTY to \"ssh\"");
713 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
714 if (sshpam_err != PAM_SUCCESS) {
715 pam_end(sshpam_handle, sshpam_err);
716 sshpam_handle = NULL;
724 expose_authinfo(const char *caller)
729 * Expose authentication information to PAM.
730 * The environment variable is versioned. Please increment the
731 * version suffix if the format of session_info changes.
733 if (sshpam_authctxt->session_info == NULL)
734 auth_info = xstrdup("");
735 else if ((auth_info = sshbuf_dup_string(
736 sshpam_authctxt->session_info)) == NULL)
737 fatal("%s: sshbuf_dup_string failed", __func__);
739 debug2("%s: auth information in SSH_AUTH_INFO_0", caller);
740 do_pam_putenv("SSH_AUTH_INFO_0", auth_info);
745 sshpam_init_ctx(Authctxt *authctxt)
747 struct pam_ctxt *ctxt;
750 debug3("PAM: %s entering", __func__);
752 * Refuse to start if we don't have PAM enabled or do_pam_account
753 * has previously failed.
755 if (!options.use_pam || sshpam_account_status == 0)
759 if (sshpam_init(authctxt) == -1) {
760 error("PAM: initialization failed");
764 expose_authinfo(__func__);
765 ctxt = xcalloc(1, sizeof *ctxt);
767 /* Start the authentication thread */
768 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
769 error("PAM: failed create sockets: %s", strerror(errno));
773 ctxt->pam_psock = socks[0];
774 ctxt->pam_csock = socks[1];
775 if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
776 error("PAM: failed to start authentication thread: %s",
788 sshpam_query(void *ctx, char **name, char **info,
789 u_int *num, char ***prompts, u_int **echo_on)
791 struct ssh *ssh = active_state; /* XXX */
792 struct sshbuf *buffer;
793 struct pam_ctxt *ctxt = ctx;
800 debug3("PAM: %s entering", __func__);
801 if ((buffer = sshbuf_new()) == NULL)
802 fatal("%s: sshbuf_new failed", __func__);
805 *prompts = xmalloc(sizeof(char *));
808 *echo_on = xmalloc(sizeof(u_int));
809 while (ssh_msg_recv(ctxt->pam_psock, buffer) == 0) {
810 if ((r = sshbuf_get_u8(buffer, &type)) != 0 ||
811 (r = sshbuf_get_cstring(buffer, &msg, &mlen)) != 0)
812 fatal("%s: buffer error: %s", __func__, ssh_err(r));
814 case PAM_PROMPT_ECHO_ON:
815 case PAM_PROMPT_ECHO_OFF:
817 len = plen + mlen + 1;
818 **prompts = xreallocarray(**prompts, 1, len);
819 strlcpy(**prompts + plen, msg, len - plen);
821 **echo_on = (type == PAM_PROMPT_ECHO_ON);
826 /* accumulate messages */
827 len = plen + mlen + 2;
828 **prompts = xreallocarray(**prompts, 1, len);
829 strlcpy(**prompts + plen, msg, len - plen);
831 strlcat(**prompts + plen, "\n", len - plen);
835 case PAM_ACCT_EXPIRED:
837 if (type == PAM_ACCT_EXPIRED)
838 sshpam_account_status = 0;
839 if (type == PAM_MAXTRIES)
840 sshpam_set_maxtries_reached(1);
843 debug3("PAM: %s", pam_strerror(sshpam_handle, type));
844 if (**prompts != NULL && strlen(**prompts) != 0) {
855 if (**prompts != NULL) {
856 /* drain any accumulated messages */
857 debug("PAM: %s", **prompts);
858 if ((r = sshbuf_put(loginmsg, **prompts,
859 strlen(**prompts))) != 0)
860 fatal("%s: buffer error: %s",
861 __func__, ssh_err(r));
865 if (type == PAM_SUCCESS) {
866 if (!sshpam_authctxt->valid ||
867 (sshpam_authctxt->pw->pw_uid == 0 &&
868 options.permit_root_login != PERMIT_YES))
869 fatal("Internal error: PAM auth "
870 "succeeded when it should have "
872 import_environments(buffer);
879 BLACKLIST_NOTIFY(BLACKLIST_BAD_USER,
880 sshpam_authctxt->user);
881 error("PAM: %s for %s%.100s from %.100s", msg,
882 sshpam_authctxt->valid ? "" : "illegal user ",
883 sshpam_authctxt->user,
884 auth_get_canonical_hostname(ssh, options.use_dns));
898 * Returns a junk password of identical length to that the user supplied.
899 * Used to mitigate timing attacks against crypt(3)/PAM stacks that
900 * vary processing time in proportion to password length.
903 fake_password(const char *wire_password)
905 const char junk[] = "\b\n\r\177INCORRECT";
907 size_t i, l = wire_password != NULL ? strlen(wire_password) : 0;
910 fatal("%s: password length too long: %zu", __func__, l);
915 for (i = 0; i < l; i++)
916 ret[i] = junk[i % (sizeof(junk) - 1)];
921 /* XXX - see also comment in auth-chall.c:verify_response */
923 sshpam_respond(void *ctx, u_int num, char **resp)
925 struct sshbuf *buffer;
926 struct pam_ctxt *ctxt = ctx;
930 debug2("PAM: %s entering, %u responses", __func__, num);
931 switch (ctxt->pam_done) {
933 sshpam_authenticated = 1;
941 error("PAM: expected one response, got %u", num);
944 if ((buffer = sshbuf_new()) == NULL)
945 fatal("%s: sshbuf_new failed", __func__);
946 if (sshpam_authctxt->valid &&
947 (sshpam_authctxt->pw->pw_uid != 0 ||
948 options.permit_root_login == PERMIT_YES)) {
949 if ((r = sshbuf_put_cstring(buffer, *resp)) != 0)
950 fatal("%s: buffer error: %s", __func__, ssh_err(r));
952 fake = fake_password(*resp);
953 if ((r = sshbuf_put_cstring(buffer, fake)) != 0)
954 fatal("%s: buffer error: %s", __func__, ssh_err(r));
957 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, buffer) == -1) {
966 sshpam_free_ctx(void *ctxtp)
968 struct pam_ctxt *ctxt = ctxtp;
970 debug3("PAM: %s entering", __func__);
971 sshpam_thread_cleanup();
974 * We don't call sshpam_cleanup() here because we may need the PAM
975 * handle at a later stage, e.g. when setting up a session. It's
976 * still on the cleanup list, so pam_end() *will* be called before
977 * the server process terminates.
981 KbdintDevice sshpam_device = {
989 KbdintDevice mm_sshpam_device = {
998 * This replaces auth-pam.c
1001 start_pam(Authctxt *authctxt)
1003 if (!options.use_pam)
1004 fatal("PAM: initialisation requested when UsePAM=no");
1006 if (sshpam_init(authctxt) == -1)
1007 fatal("PAM: initialisation failed");
1018 do_pam_account(void)
1020 debug("%s: called", __func__);
1021 if (sshpam_account_status != -1)
1022 return (sshpam_account_status);
1024 expose_authinfo(__func__);
1026 sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
1027 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
1028 pam_strerror(sshpam_handle, sshpam_err));
1030 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
1031 sshpam_account_status = 0;
1032 return (sshpam_account_status);
1035 if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
1036 sshpam_password_change_required(1);
1038 sshpam_account_status = 1;
1039 return (sshpam_account_status);
1043 do_pam_setcred(int init)
1045 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1046 (const void *)&store_conv);
1047 if (sshpam_err != PAM_SUCCESS)
1048 fatal("PAM: failed to set PAM_CONV: %s",
1049 pam_strerror(sshpam_handle, sshpam_err));
1051 debug("PAM: establishing credentials");
1052 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
1054 debug("PAM: reinitializing credentials");
1055 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
1057 if (sshpam_err == PAM_SUCCESS) {
1058 sshpam_cred_established = 1;
1061 if (sshpam_authenticated)
1062 fatal("PAM: pam_setcred(): %s",
1063 pam_strerror(sshpam_handle, sshpam_err));
1065 debug("PAM: pam_setcred(): %s",
1066 pam_strerror(sshpam_handle, sshpam_err));
1070 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
1071 struct pam_response **resp, void *data)
1073 char input[PAM_MAX_MSG_SIZE];
1074 struct pam_response *reply;
1077 debug3("PAM: %s called with %d messages", __func__, n);
1081 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
1082 return (PAM_CONV_ERR);
1084 if ((reply = calloc(n, sizeof(*reply))) == NULL)
1085 return (PAM_CONV_ERR);
1087 for (i = 0; i < n; ++i) {
1088 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1089 case PAM_PROMPT_ECHO_OFF:
1091 read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
1093 reply[i].resp_retcode = PAM_SUCCESS;
1095 case PAM_PROMPT_ECHO_ON:
1096 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1097 if (fgets(input, sizeof input, stdin) == NULL)
1099 if ((reply[i].resp = strdup(input)) == NULL)
1101 reply[i].resp_retcode = PAM_SUCCESS;
1105 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1106 reply[i].resp_retcode = PAM_SUCCESS;
1113 return (PAM_SUCCESS);
1116 for(i = 0; i < n; i++) {
1117 free(reply[i].resp);
1120 return (PAM_CONV_ERR);
1123 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
1126 * XXX this should be done in the authentication phase, but ssh1 doesn't
1130 do_pam_chauthtok(void)
1133 fatal("Password expired (unable to change with privsep)");
1134 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1135 (const void *)&tty_conv);
1136 if (sshpam_err != PAM_SUCCESS)
1137 fatal("PAM: failed to set PAM_CONV: %s",
1138 pam_strerror(sshpam_handle, sshpam_err));
1139 debug("PAM: changing password");
1140 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
1141 if (sshpam_err != PAM_SUCCESS)
1142 fatal("PAM: pam_chauthtok(): %s",
1143 pam_strerror(sshpam_handle, sshpam_err));
1147 do_pam_session(struct ssh *ssh)
1149 debug3("PAM: opening session");
1151 expose_authinfo(__func__);
1153 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1154 (const void *)&store_conv);
1155 if (sshpam_err != PAM_SUCCESS)
1156 fatal("PAM: failed to set PAM_CONV: %s",
1157 pam_strerror(sshpam_handle, sshpam_err));
1158 sshpam_err = pam_open_session(sshpam_handle, 0);
1159 if (sshpam_err == PAM_SUCCESS)
1160 sshpam_session_open = 1;
1162 sshpam_session_open = 0;
1163 auth_restrict_session(ssh);
1164 error("PAM: pam_open_session(): %s",
1165 pam_strerror(sshpam_handle, sshpam_err));
1171 is_pam_session_open(void)
1173 return sshpam_session_open;
1177 * Set a PAM environment string. We need to do this so that the session
1178 * modules can handle things like Kerberos/GSI credentials that appear
1179 * during the ssh authentication process.
1182 do_pam_putenv(char *name, char *value)
1185 #ifdef HAVE_PAM_PUTENV
1189 len = strlen(name) + strlen(value) + 2;
1190 compound = xmalloc(len);
1192 snprintf(compound, len, "%s=%s", name, value);
1193 ret = pam_putenv(sshpam_handle, compound);
1201 fetch_pam_child_environment(void)
1207 fetch_pam_environment(void)
1209 return (pam_getenvlist(sshpam_handle));
1213 free_pam_environment(char **env)
1220 for (envp = env; *envp; envp++)
1226 * "Blind" conversation function for password authentication. Assumes that
1227 * echo-off prompts are for the password and stores messages for later
1231 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1232 struct pam_response **resp, void *data)
1234 struct pam_response *reply;
1238 debug3("PAM: %s called with %d messages", __func__, n);
1242 if (n <= 0 || n > PAM_MAX_NUM_MSG)
1243 return (PAM_CONV_ERR);
1245 if ((reply = calloc(n, sizeof(*reply))) == NULL)
1246 return (PAM_CONV_ERR);
1248 for (i = 0; i < n; ++i) {
1249 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1250 case PAM_PROMPT_ECHO_OFF:
1251 if (sshpam_password == NULL)
1253 if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1255 reply[i].resp_retcode = PAM_SUCCESS;
1259 len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1261 if ((r = sshbuf_putf(loginmsg, "%s\n",
1262 PAM_MSG_MEMBER(msg, i, msg))) != 0)
1263 fatal("%s: buffer error: %s",
1264 __func__, ssh_err(r));
1266 if ((reply[i].resp = strdup("")) == NULL)
1268 reply[i].resp_retcode = PAM_SUCCESS;
1275 return (PAM_SUCCESS);
1278 for(i = 0; i < n; i++) {
1279 free(reply[i].resp);
1282 return (PAM_CONV_ERR);
1285 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1288 * Attempt password authentication via PAM
1291 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1293 int flags = (options.permit_empty_passwd == 0 ?
1294 PAM_DISALLOW_NULL_AUTHTOK : 0);
1297 if (!options.use_pam || sshpam_handle == NULL)
1298 fatal("PAM: %s called when PAM disabled or failed to "
1299 "initialise.", __func__);
1301 sshpam_password = password;
1302 sshpam_authctxt = authctxt;
1305 * If the user logging in is invalid, or is root but is not permitted
1306 * by PermitRootLogin, use an invalid password to prevent leaking
1307 * information via timing (eg if the PAM config has a delay on fail).
1309 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1310 options.permit_root_login != PERMIT_YES))
1311 sshpam_password = fake = fake_password(password);
1313 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1314 (const void *)&passwd_conv);
1315 if (sshpam_err != PAM_SUCCESS)
1316 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1317 pam_strerror(sshpam_handle, sshpam_err));
1319 sshpam_err = pam_authenticate(sshpam_handle, flags);
1320 sshpam_password = NULL;
1322 if (sshpam_err == PAM_MAXTRIES)
1323 sshpam_set_maxtries_reached(1);
1324 if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1325 debug("PAM: password authentication accepted for %.100s",
1329 debug("PAM: password authentication failed for %.100s: %s",
1330 authctxt->valid ? authctxt->user : "an illegal user",
1331 pam_strerror(sshpam_handle, sshpam_err));
1337 sshpam_get_maxtries_reached(void)
1339 return sshpam_maxtries_reached;
1343 sshpam_set_maxtries_reached(int reached)
1345 if (reached == 0 || sshpam_maxtries_reached)
1347 sshpam_maxtries_reached = 1;
1348 options.password_authentication = 0;
1349 options.kbd_interactive_authentication = 0;
1350 options.challenge_response_authentication = 0;
1352 #endif /* USE_PAM */