auth-pam.c

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