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