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         debug3("%s %d", __func__, reqd);
 292         if (sshpam_authctxt == NULL)
 293                 fatal("%s: PAM authctxt not initialized", __func__);
 294         sshpam_authctxt->force_pwchange = reqd;
 295         if (reqd) {
 296                 no_port_forwarding_flag |= 2;
 297                 no_agent_forwarding_flag |= 2;
 298                 no_x11_forwarding_flag |= 2;
 299         } else {
 300                 no_port_forwarding_flag &= ~2;
 301                 no_agent_forwarding_flag &= ~2;
 302                 no_x11_forwarding_flag &= ~2;
 303         }
 304 }
 305
 306 /* Import regular and PAM environment from subprocess */
 307 static void
 308 import_environments(Buffer *b)
 309 {
 310         char *env;
 311         u_int i, num_env;
 312         int err;
 313
 314         debug3("PAM: %s entering", __func__);
 315
 316 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 317         /* Import variables set by do_pam_account */
 318         sshpam_account_status = buffer_get_int(b);
 319         sshpam_password_change_required(buffer_get_int(b));
 320
 321         /* Import environment from subprocess */
 322         num_env = buffer_get_int(b);
 323         if (num_env > 1024)
 324                 fatal("%s: received %u environment variables, expected <= 1024",
 325                     __func__, num_env);
 326         sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env));
 327         debug3("PAM: num env strings %d", num_env);
 328         for(i = 0; i < num_env; i++)
 329                 sshpam_env[i] = buffer_get_string(b, NULL);
 330
 331         sshpam_env[num_env] = NULL;
 332
 333         /* Import PAM environment from subprocess */
 334         num_env = buffer_get_int(b);
 335         debug("PAM: num PAM env strings %d", num_env);
 336         for(i = 0; i < num_env; i++) {
 337                 env = buffer_get_string(b, NULL);
 338
 339 #ifdef HAVE_PAM_PUTENV
 340                 /* Errors are not fatal here */
 341                 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
 342                         error("PAM: pam_putenv: %s",
 343                             pam_strerror(sshpam_handle, sshpam_err));
 344                 }
 345 #endif
 346         }
 347 #endif
 348 }
 349
 350 /*
 351  * Conversation function for authentication thread.
 352  */
 353 static int
 354 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
 355     struct pam_response **resp, void *data)
 356 {
 357         Buffer buffer;
 358         struct pam_ctxt *ctxt;
 359         struct pam_response *reply;
 360         int i;
 361
 362         debug3("PAM: %s entering, %d messages", __func__, n);
 363         *resp = NULL;
 364
 365         if (data == NULL) {
 366                 error("PAM: conversation function passed a null context");
 367                 return (PAM_CONV_ERR);
 368         }
 369         ctxt = data;
 370         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 371                 return (PAM_CONV_ERR);
 372
 373         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 374                 return (PAM_CONV_ERR);
 375
 376         buffer_init(&buffer);
 377         for (i = 0; i < n; ++i) {
 378                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 379                 case PAM_PROMPT_ECHO_OFF:
 380                 case PAM_PROMPT_ECHO_ON:
 381                         buffer_put_cstring(&buffer,
 382                             PAM_MSG_MEMBER(msg, i, msg));
 383                         if (ssh_msg_send(ctxt->pam_csock,
 384                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 385                                 goto fail;
 386                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 387                                 goto fail;
 388                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 389                                 goto fail;
 390                         reply[i].resp = buffer_get_string(&buffer, NULL);
 391                         break;
 392                 case PAM_ERROR_MSG:
 393                 case PAM_TEXT_INFO:
 394                         buffer_put_cstring(&buffer,
 395                             PAM_MSG_MEMBER(msg, i, msg));
 396                         if (ssh_msg_send(ctxt->pam_csock,
 397                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 398                                 goto fail;
 399                         break;
 400                 default:
 401                         goto fail;
 402                 }
 403                 buffer_clear(&buffer);
 404         }
 405         buffer_free(&buffer);
 406         *resp = reply;
 407         return (PAM_SUCCESS);
 408
 409  fail:
 410         for(i = 0; i < n; i++) {
 411                 free(reply[i].resp);
 412         }
 413         free(reply);
 414         buffer_free(&buffer);
 415         return (PAM_CONV_ERR);
 416 }
 417
 418 /*
 419  * Authentication thread.
 420  */
 421 static void *
 422 sshpam_thread(void *ctxtp)
 423 {
 424         struct pam_ctxt *ctxt = ctxtp;
 425         Buffer buffer;
 426         struct pam_conv sshpam_conv;
 427         int flags = (options.permit_empty_passwd == 0 ?
 428             PAM_DISALLOW_NULL_AUTHTOK : 0);
 429 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 430         extern char **environ;
 431         char **env_from_pam;
 432         u_int i;
 433         const char *pam_user;
 434         const char **ptr_pam_user = &pam_user;
 435         char *tz = getenv("TZ");
 436
 437         sshpam_err = pam_get_item(sshpam_handle, PAM_USER,
 438             (sshpam_const void **)ptr_pam_user);
 439         if (sshpam_err != PAM_SUCCESS)
 440                 goto auth_fail;
 441
 442         environ[0] = NULL;
 443         if (tz != NULL)
 444                 if (setenv("TZ", tz, 1) == -1)
 445                         error("PAM: could not set TZ environment: %s",
 446                             strerror(errno));
 447
 448         if (sshpam_authctxt != NULL) {
 449                 setproctitle("%s [pam]",
 450                     sshpam_authctxt->valid ? pam_user : "unknown");
 451         }
 452 #endif
 453
 454         sshpam_conv.conv = sshpam_thread_conv;
 455         sshpam_conv.appdata_ptr = ctxt;
 456
 457         if (sshpam_authctxt == NULL)
 458                 fatal("%s: PAM authctxt not initialized", __func__);
 459
 460         buffer_init(&buffer);
 461         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 462             (const void *)&sshpam_conv);
 463         if (sshpam_err != PAM_SUCCESS)
 464                 goto auth_fail;
 465         sshpam_err = pam_authenticate(sshpam_handle, flags);
 466         if (sshpam_err == PAM_MAXTRIES)
 467                 sshpam_set_maxtries_reached(1);
 468         if (sshpam_err != PAM_SUCCESS)
 469                 goto auth_fail;
 470
 471         if (!do_pam_account()) {
 472                 sshpam_err = PAM_ACCT_EXPIRED;
 473                 goto auth_fail;
 474         }
 475         if (sshpam_authctxt->force_pwchange) {
 476                 sshpam_err = pam_chauthtok(sshpam_handle,
 477                     PAM_CHANGE_EXPIRED_AUTHTOK);
 478                 if (sshpam_err != PAM_SUCCESS)
 479                         goto auth_fail;
 480                 sshpam_password_change_required(0);
 481         }
 482
 483         buffer_put_cstring(&buffer, "OK");
 484
 485 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 486         /* Export variables set by do_pam_account */
 487         buffer_put_int(&buffer, sshpam_account_status);
 488         buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);
 489
 490         /* Export any environment strings set in child */
 491         for(i = 0; environ[i] != NULL; i++)
 492                 ; /* Count */
 493         buffer_put_int(&buffer, i);
 494         for(i = 0; environ[i] != NULL; i++)
 495                 buffer_put_cstring(&buffer, environ[i]);
 496
 497         /* Export any environment strings set by PAM in child */
 498         env_from_pam = pam_getenvlist(sshpam_handle);
 499         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 500                 ; /* Count */
 501         buffer_put_int(&buffer, i);
 502         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 503                 buffer_put_cstring(&buffer, env_from_pam[i]);
 504 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */
 505
 506         /* XXX - can't do much about an error here */
 507         ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
 508         buffer_free(&buffer);
 509         pthread_exit(NULL);
 510
 511  auth_fail:
 512         buffer_put_cstring(&buffer,
 513             pam_strerror(sshpam_handle, sshpam_err));
 514         /* XXX - can't do much about an error here */
 515         if (sshpam_err == PAM_ACCT_EXPIRED)
 516                 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, &buffer);
 517         else if (sshpam_maxtries_reached)
 518                 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, &buffer);
 519         else
 520                 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
 521         buffer_free(&buffer);
 522         pthread_exit(NULL);
 523
 524         return (NULL); /* Avoid warning for non-pthread case */
 525 }
 526
 527 void
 528 sshpam_thread_cleanup(void)
 529 {
 530         struct pam_ctxt *ctxt = cleanup_ctxt;
 531
 532         debug3("PAM: %s entering", __func__);
 533         if (ctxt != NULL && ctxt->pam_thread != 0) {
 534                 pthread_cancel(ctxt->pam_thread);
 535                 pthread_join(ctxt->pam_thread, NULL);
 536                 close(ctxt->pam_psock);
 537                 close(ctxt->pam_csock);
 538                 memset(ctxt, 0, sizeof(*ctxt));
 539                 cleanup_ctxt = NULL;
 540         }
 541 }
 542
 543 static int
 544 sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
 545     struct pam_response **resp, void *data)
 546 {
 547         debug3("PAM: %s entering, %d messages", __func__, n);
 548         return (PAM_CONV_ERR);
 549 }
 550
 551 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
 552
 553 static int
 554 sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
 555     struct pam_response **resp, void *data)
 556 {
 557         struct pam_response *reply;
 558         int i;
 559         size_t len;
 560
 561         debug3("PAM: %s called with %d messages", __func__, n);
 562         *resp = NULL;
 563
 564         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 565                 return (PAM_CONV_ERR);
 566
 567         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 568                 return (PAM_CONV_ERR);
 569
 570         for (i = 0; i < n; ++i) {
 571                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 572                 case PAM_ERROR_MSG:
 573                 case PAM_TEXT_INFO:
 574                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
 575                         buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
 576                         buffer_append(&loginmsg, "\n", 1 );
 577                         reply[i].resp_retcode = PAM_SUCCESS;
 578                         break;
 579                 default:
 580                         goto fail;
 581                 }
 582         }
 583         *resp = reply;
 584         return (PAM_SUCCESS);
 585
 586  fail:
 587         for(i = 0; i < n; i++) {
 588                 free(reply[i].resp);
 589         }
 590         free(reply);
 591         return (PAM_CONV_ERR);
 592 }
 593
 594 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
 595
 596 void
 597 sshpam_cleanup(void)
 598 {
 599         if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor()))
 600                 return;
 601         debug("PAM: cleanup");
 602         pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 603         if (sshpam_session_open) {
 604                 debug("PAM: closing session");
 605                 pam_close_session(sshpam_handle, PAM_SILENT);
 606                 sshpam_session_open = 0;
 607         }
 608         if (sshpam_cred_established) {
 609                 debug("PAM: deleting credentials");
 610                 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
 611                 sshpam_cred_established = 0;
 612         }
 613         sshpam_authenticated = 0;
 614         pam_end(sshpam_handle, sshpam_err);
 615         sshpam_handle = NULL;
 616 }
 617
 618 static int
 619 sshpam_init(Authctxt *authctxt)
 620 {
 621         const char *pam_rhost, *pam_user, *user = authctxt->user;
 622         const char **ptr_pam_user = &pam_user;
 623         struct ssh *ssh = active_state; /* XXX */
 624
 625         if (sshpam_handle != NULL) {
 626                 /* We already have a PAM context; check if the user matches */
 627                 sshpam_err = pam_get_item(sshpam_handle,
 628                     PAM_USER, (sshpam_const void **)ptr_pam_user);
 629                 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
 630                         return (0);
 631                 pam_end(sshpam_handle, sshpam_err);
 632                 sshpam_handle = NULL;
 633         }
 634         debug("PAM: initializing for \"%s\"", user);
 635         sshpam_err =
 636             pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
 637         sshpam_authctxt = authctxt;
 638
 639         if (sshpam_err != PAM_SUCCESS) {
 640                 pam_end(sshpam_handle, sshpam_err);
 641                 sshpam_handle = NULL;
 642                 return (-1);
 643         }
 644         pam_rhost = auth_get_canonical_hostname(ssh, options.use_dns);
 645         debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
 646         sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
 647         if (sshpam_err != PAM_SUCCESS) {
 648                 pam_end(sshpam_handle, sshpam_err);
 649                 sshpam_handle = NULL;
 650                 return (-1);
 651         }
 652 #ifdef PAM_TTY_KLUDGE
 653         /*
 654          * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
 655          * sshd doesn't set the tty until too late in the auth process and
 656          * may not even set one (for tty-less connections)
 657          */
 658         debug("PAM: setting PAM_TTY to \"ssh\"");
 659         sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
 660         if (sshpam_err != PAM_SUCCESS) {
 661                 pam_end(sshpam_handle, sshpam_err);
 662                 sshpam_handle = NULL;
 663                 return (-1);
 664         }
 665 #endif
 666         return (0);
 667 }
 668
 669 static void *
 670 sshpam_init_ctx(Authctxt *authctxt)
 671 {
 672         struct pam_ctxt *ctxt;
 673         int socks[2];
 674
 675         debug3("PAM: %s entering", __func__);
 676         /*
 677          * Refuse to start if we don't have PAM enabled or do_pam_account
 678          * has previously failed.
 679          */
 680         if (!options.use_pam || sshpam_account_status == 0)
 681                 return NULL;
 682
 683         /* Initialize PAM */
 684         if (sshpam_init(authctxt) == -1) {
 685                 error("PAM: initialization failed");
 686                 return (NULL);
 687         }
 688
 689         ctxt = xcalloc(1, sizeof *ctxt);
 690
 691         /* Start the authentication thread */
 692         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
 693                 error("PAM: failed create sockets: %s", strerror(errno));
 694                 free(ctxt);
 695                 return (NULL);
 696         }
 697         ctxt->pam_psock = socks[0];
 698         ctxt->pam_csock = socks[1];
 699         if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
 700                 error("PAM: failed to start authentication thread: %s",
 701                     strerror(errno));
 702                 close(socks[0]);
 703                 close(socks[1]);
 704                 free(ctxt);
 705                 return (NULL);
 706         }
 707         cleanup_ctxt = ctxt;
 708         return (ctxt);
 709 }
 710
 711 static int
 712 sshpam_query(void *ctx, char **name, char **info,
 713     u_int *num, char ***prompts, u_int **echo_on)
 714 {
 715         struct ssh *ssh = active_state; /* XXX */
 716         Buffer buffer;
 717         struct pam_ctxt *ctxt = ctx;
 718         size_t plen;
 719         u_char type;
 720         char *msg;
 721         size_t len, mlen;
 722
 723         debug3("PAM: %s entering", __func__);
 724         buffer_init(&buffer);
 725         *name = xstrdup("");
 726         *info = xstrdup("");
 727         *prompts = xmalloc(sizeof(char *));
 728         **prompts = NULL;
 729         plen = 0;
 730         *echo_on = xmalloc(sizeof(u_int));
 731         while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
 732                 type = buffer_get_char(&buffer);
 733                 msg = buffer_get_string(&buffer, NULL);
 734                 mlen = strlen(msg);
 735                 switch (type) {
 736                 case PAM_PROMPT_ECHO_ON:
 737                 case PAM_PROMPT_ECHO_OFF:
 738                         *num = 1;
 739                         len = plen + mlen + 1;
 740                         **prompts = xreallocarray(**prompts, 1, len);
 741                         strlcpy(**prompts + plen, msg, len - plen);
 742                         plen += mlen;
 743                         **echo_on = (type == PAM_PROMPT_ECHO_ON);
 744                         free(msg);
 745                         return (0);
 746                 case PAM_ERROR_MSG:
 747                 case PAM_TEXT_INFO:
 748                         /* accumulate messages */
 749                         len = plen + mlen + 2;
 750                         **prompts = xreallocarray(**prompts, 1, len);
 751                         strlcpy(**prompts + plen, msg, len - plen);
 752                         plen += mlen;
 753                         strlcat(**prompts + plen, "\n", len - plen);
 754                         plen++;
 755                         free(msg);
 756                         break;
 757                 case PAM_ACCT_EXPIRED:
 758                 case PAM_MAXTRIES:
 759                         if (type == PAM_ACCT_EXPIRED)
 760                                 sshpam_account_status = 0;
 761                         if (type == PAM_MAXTRIES)
 762                                 sshpam_set_maxtries_reached(1);
 763                         /* FALLTHROUGH */
 764                 case PAM_AUTH_ERR:
 765                         debug3("PAM: %s", pam_strerror(sshpam_handle, type));
 766                         if (**prompts != NULL && strlen(**prompts) != 0) {
 767                                 *info = **prompts;
 768                                 **prompts = NULL;
 769                                 *num = 0;
 770                                 **echo_on = 0;
 771                                 ctxt->pam_done = -1;
 772                                 free(msg);
 773                                 return 0;
 774                         }
 775                         /* FALLTHROUGH */
 776                 case PAM_SUCCESS:
 777                         if (**prompts != NULL) {
 778                                 /* drain any accumulated messages */
 779                                 debug("PAM: %s", **prompts);
 780                                 buffer_append(&loginmsg, **prompts,
 781                                     strlen(**prompts));
 782                                 free(**prompts);
 783                                 **prompts = NULL;
 784                         }
 785                         if (type == PAM_SUCCESS) {
 786                                 if (!sshpam_authctxt->valid ||
 787                                     (sshpam_authctxt->pw->pw_uid == 0 &&
 788                                     options.permit_root_login != PERMIT_YES))
 789                                         fatal("Internal error: PAM auth "
 790                                             "succeeded when it should have "
 791                                             "failed");
 792                                 import_environments(&buffer);
 793                                 *num = 0;
 794                                 **echo_on = 0;
 795                                 ctxt->pam_done = 1;
 796                                 free(msg);
 797                                 return (0);
 798                         }
 799                         BLACKLIST_NOTIFY(BLACKLIST_BAD_USER,
 800                             sshpam_authctxt->user);
 801                         error("PAM: %s for %s%.100s from %.100s", msg,
 802                             sshpam_authctxt->valid ? "" : "illegal user ",
 803                             sshpam_authctxt->user,
 804                             auth_get_canonical_hostname(ssh, options.use_dns));
 805                         /* FALLTHROUGH */
 806                 default:
 807                         *num = 0;
 808                         **echo_on = 0;
 809                         free(msg);
 810                         ctxt->pam_done = -1;
 811                         return (-1);
 812                 }
 813         }
 814         return (-1);
 815 }
 816
 817 /*
 818  * Returns a junk password of identical length to that the user supplied.
 819  * Used to mitigate timing attacks against crypt(3)/PAM stacks that
 820  * vary processing time in proportion to password length.
 821  */
 822 static char *
 823 fake_password(const char *wire_password)
 824 {
 825         const char junk[] = "\b\n\r\177INCORRECT";
 826         char *ret = NULL;
 827         size_t i, l = wire_password != NULL ? strlen(wire_password) : 0;
 828
 829         if (l >= INT_MAX)
 830                 fatal("%s: password length too long: %zu", __func__, l);
 831
 832         ret = malloc(l + 1);
 833         if (ret == NULL)
 834                 return NULL;
 835         for (i = 0; i < l; i++)
 836                 ret[i] = junk[i % (sizeof(junk) - 1)];
 837         ret[i] = '\0';
 838         return ret;
 839 }
 840
 841 /* XXX - see also comment in auth-chall.c:verify_response */
 842 static int
 843 sshpam_respond(void *ctx, u_int num, char **resp)
 844 {
 845         Buffer buffer;
 846         struct pam_ctxt *ctxt = ctx;
 847         char *fake;
 848
 849         debug2("PAM: %s entering, %u responses", __func__, num);
 850         switch (ctxt->pam_done) {
 851         case 1:
 852                 sshpam_authenticated = 1;
 853                 return (0);
 854         case 0:
 855                 break;
 856         default:
 857                 return (-1);
 858         }
 859         if (num != 1) {
 860                 error("PAM: expected one response, got %u", num);
 861                 return (-1);
 862         }
 863         buffer_init(&buffer);
 864         if (sshpam_authctxt->valid &&
 865             (sshpam_authctxt->pw->pw_uid != 0 ||
 866             options.permit_root_login == PERMIT_YES))
 867                 buffer_put_cstring(&buffer, *resp);
 868         else {
 869                 fake = fake_password(*resp);
 870                 buffer_put_cstring(&buffer, fake);
 871                 free(fake);
 872         }
 873         if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
 874                 buffer_free(&buffer);
 875                 return (-1);
 876         }
 877         buffer_free(&buffer);
 878         return (1);
 879 }
 880
 881 static void
 882 sshpam_free_ctx(void *ctxtp)
 883 {
 884         struct pam_ctxt *ctxt = ctxtp;
 885
 886         debug3("PAM: %s entering", __func__);
 887         sshpam_thread_cleanup();
 888         free(ctxt);
 889         /*
 890          * We don't call sshpam_cleanup() here because we may need the PAM
 891          * handle at a later stage, e.g. when setting up a session.  It's
 892          * still on the cleanup list, so pam_end() *will* be called before
 893          * the server process terminates.
 894          */
 895 }
 896
 897 KbdintDevice sshpam_device = {
 898         "pam",
 899         sshpam_init_ctx,
 900         sshpam_query,
 901         sshpam_respond,
 902         sshpam_free_ctx
 903 };
 904
 905 KbdintDevice mm_sshpam_device = {
 906         "pam",
 907         mm_sshpam_init_ctx,
 908         mm_sshpam_query,
 909         mm_sshpam_respond,
 910         mm_sshpam_free_ctx
 911 };
 912
 913 /*
 914  * This replaces auth-pam.c
 915  */
 916 void
 917 start_pam(Authctxt *authctxt)
 918 {
 919         if (!options.use_pam)
 920                 fatal("PAM: initialisation requested when UsePAM=no");
 921
 922         if (sshpam_init(authctxt) == -1)
 923                 fatal("PAM: initialisation failed");
 924 }
 925
 926 void
 927 finish_pam(void)
 928 {
 929         sshpam_cleanup();
 930 }
 931
 932 static void
 933 expose_authinfo(const char *caller)
 934 {
 935         char *auth_info;
 936
 937         /*
 938          * Expose authentication information to PAM.
 939          * The enviornment variable is versioned. Please increment the
 940          * version suffix if the format of session_info changes.
 941          */
 942         if (sshpam_authctxt->session_info == NULL)
 943                 auth_info = xstrdup("");
 944         else if ((auth_info = sshbuf_dup_string(
 945             sshpam_authctxt->session_info)) == NULL)
 946                 fatal("%s: sshbuf_dup_string failed", __func__);
 947
 948         debug2("%s: auth information in SSH_AUTH_INFO_0", caller);
 949         do_pam_putenv("SSH_AUTH_INFO_0", auth_info);
 950         free(auth_info);
 951 }
 952
 953 u_int
 954 do_pam_account(void)
 955 {
 956         debug("%s: called", __func__);
 957         if (sshpam_account_status != -1)
 958                 return (sshpam_account_status);
 959
 960         expose_authinfo(__func__);
 961
 962         sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
 963         debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
 964             pam_strerror(sshpam_handle, sshpam_err));
 965
 966         if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
 967                 sshpam_account_status = 0;
 968                 return (sshpam_account_status);
 969         }
 970
 971         if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
 972                 sshpam_password_change_required(1);
 973
 974         sshpam_account_status = 1;
 975         return (sshpam_account_status);
 976 }
 977
 978 void
 979 do_pam_setcred(int init)
 980 {
 981         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 982             (const void *)&store_conv);
 983         if (sshpam_err != PAM_SUCCESS)
 984                 fatal("PAM: failed to set PAM_CONV: %s",
 985                     pam_strerror(sshpam_handle, sshpam_err));
 986         if (init) {
 987                 debug("PAM: establishing credentials");
 988                 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
 989         } else {
 990                 debug("PAM: reinitializing credentials");
 991                 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
 992         }
 993         if (sshpam_err == PAM_SUCCESS) {
 994                 sshpam_cred_established = 1;
 995                 return;
 996         }
 997         if (sshpam_authenticated)
 998                 fatal("PAM: pam_setcred(): %s",
 999                     pam_strerror(sshpam_handle, sshpam_err));
1000         else
1001                 debug("PAM: pam_setcred(): %s",
1002                     pam_strerror(sshpam_handle, sshpam_err));
1003 }
1004
1005 static int
1006 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
1007     struct pam_response **resp, void *data)
1008 {
1009         char input[PAM_MAX_MSG_SIZE];
1010         struct pam_response *reply;
1011         int i;
1012
1013         debug3("PAM: %s called with %d messages", __func__, n);
1014
1015         *resp = NULL;
1016
1017         if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
1018                 return (PAM_CONV_ERR);
1019
1020         if ((reply = calloc(n, sizeof(*reply))) == NULL)
1021                 return (PAM_CONV_ERR);
1022
1023         for (i = 0; i < n; ++i) {
1024                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1025                 case PAM_PROMPT_ECHO_OFF:
1026                         reply[i].resp =
1027                             read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
1028                             RP_ALLOW_STDIN);
1029                         reply[i].resp_retcode = PAM_SUCCESS;
1030                         break;
1031                 case PAM_PROMPT_ECHO_ON:
1032                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1033                         if (fgets(input, sizeof input, stdin) == NULL)
1034                                 input[0] = '\0';
1035                         if ((reply[i].resp = strdup(input)) == NULL)
1036                                 goto fail;
1037                         reply[i].resp_retcode = PAM_SUCCESS;
1038                         break;
1039                 case PAM_ERROR_MSG:
1040                 case PAM_TEXT_INFO:
1041                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1042                         reply[i].resp_retcode = PAM_SUCCESS;
1043                         break;
1044                 default:
1045                         goto fail;
1046                 }
1047         }
1048         *resp = reply;
1049         return (PAM_SUCCESS);
1050
1051  fail:
1052         for(i = 0; i < n; i++) {
1053                 free(reply[i].resp);
1054         }
1055         free(reply);
1056         return (PAM_CONV_ERR);
1057 }
1058
1059 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
1060
1061 /*
1062  * XXX this should be done in the authentication phase, but ssh1 doesn't
1063  * support that
1064  */
1065 void
1066 do_pam_chauthtok(void)
1067 {
1068         if (use_privsep)
1069                 fatal("Password expired (unable to change with privsep)");
1070         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1071             (const void *)&tty_conv);
1072         if (sshpam_err != PAM_SUCCESS)
1073                 fatal("PAM: failed to set PAM_CONV: %s",
1074                     pam_strerror(sshpam_handle, sshpam_err));
1075         debug("PAM: changing password");
1076         sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
1077         if (sshpam_err != PAM_SUCCESS)
1078                 fatal("PAM: pam_chauthtok(): %s",
1079                     pam_strerror(sshpam_handle, sshpam_err));
1080 }
1081
1082 void
1083 do_pam_session(void)
1084 {
1085         debug3("PAM: opening session");
1086
1087         expose_authinfo(__func__);
1088
1089         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1090             (const void *)&store_conv);
1091         if (sshpam_err != PAM_SUCCESS)
1092                 fatal("PAM: failed to set PAM_CONV: %s",
1093                     pam_strerror(sshpam_handle, sshpam_err));
1094         sshpam_err = pam_open_session(sshpam_handle, 0);
1095         if (sshpam_err == PAM_SUCCESS)
1096                 sshpam_session_open = 1;
1097         else {
1098                 sshpam_session_open = 0;
1099                 disable_forwarding();
1100                 error("PAM: pam_open_session(): %s",
1101                     pam_strerror(sshpam_handle, sshpam_err));
1102         }
1103
1104 }
1105
1106 int
1107 is_pam_session_open(void)
1108 {
1109         return sshpam_session_open;
1110 }
1111
1112 /*
1113  * Set a PAM environment string. We need to do this so that the session
1114  * modules can handle things like Kerberos/GSI credentials that appear
1115  * during the ssh authentication process.
1116  */
1117 int
1118 do_pam_putenv(char *name, char *value)
1119 {
1120         int ret = 1;
1121 #ifdef HAVE_PAM_PUTENV
1122         char *compound;
1123         size_t len;
1124
1125         len = strlen(name) + strlen(value) + 2;
1126         compound = xmalloc(len);
1127
1128         snprintf(compound, len, "%s=%s", name, value);
1129         ret = pam_putenv(sshpam_handle, compound);
1130         free(compound);
1131 #endif
1132
1133         return (ret);
1134 }
1135
1136 char **
1137 fetch_pam_child_environment(void)
1138 {
1139         return sshpam_env;
1140 }
1141
1142 char **
1143 fetch_pam_environment(void)
1144 {
1145         return (pam_getenvlist(sshpam_handle));
1146 }
1147
1148 void
1149 free_pam_environment(char **env)
1150 {
1151         char **envp;
1152
1153         if (env == NULL)
1154                 return;
1155
1156         for (envp = env; *envp; envp++)
1157                 free(*envp);
1158         free(env);
1159 }
1160
1161 /*
1162  * "Blind" conversation function for password authentication.  Assumes that
1163  * echo-off prompts are for the password and stores messages for later
1164  * display.
1165  */
1166 static int
1167 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1168     struct pam_response **resp, void *data)
1169 {
1170         struct pam_response *reply;
1171         int i;
1172         size_t len;
1173
1174         debug3("PAM: %s called with %d messages", __func__, n);
1175
1176         *resp = NULL;
1177
1178         if (n <= 0 || n > PAM_MAX_NUM_MSG)
1179                 return (PAM_CONV_ERR);
1180
1181         if ((reply = calloc(n, sizeof(*reply))) == NULL)
1182                 return (PAM_CONV_ERR);
1183
1184         for (i = 0; i < n; ++i) {
1185                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1186                 case PAM_PROMPT_ECHO_OFF:
1187                         if (sshpam_password == NULL)
1188                                 goto fail;
1189                         if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1190                                 goto fail;
1191                         reply[i].resp_retcode = PAM_SUCCESS;
1192                         break;
1193                 case PAM_ERROR_MSG:
1194                 case PAM_TEXT_INFO:
1195                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1196                         if (len > 0) {
1197                                 buffer_append(&loginmsg,
1198                                     PAM_MSG_MEMBER(msg, i, msg), len);
1199                                 buffer_append(&loginmsg, "\n", 1);
1200                         }
1201                         if ((reply[i].resp = strdup("")) == NULL)
1202                                 goto fail;
1203                         reply[i].resp_retcode = PAM_SUCCESS;
1204                         break;
1205                 default:
1206                         goto fail;
1207                 }
1208         }
1209         *resp = reply;
1210         return (PAM_SUCCESS);
1211
1212  fail:
1213         for(i = 0; i < n; i++) {
1214                 free(reply[i].resp);
1215         }
1216         free(reply);
1217         return (PAM_CONV_ERR);
1218 }
1219
1220 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1221
1222 /*
1223  * Attempt password authentication via PAM
1224  */
1225 int
1226 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1227 {
1228         int flags = (options.permit_empty_passwd == 0 ?
1229             PAM_DISALLOW_NULL_AUTHTOK : 0);
1230         char *fake = NULL;
1231
1232         if (!options.use_pam || sshpam_handle == NULL)
1233                 fatal("PAM: %s called when PAM disabled or failed to "
1234                     "initialise.", __func__);
1235
1236         sshpam_password = password;
1237         sshpam_authctxt = authctxt;
1238
1239         /*
1240          * If the user logging in is invalid, or is root but is not permitted
1241          * by PermitRootLogin, use an invalid password to prevent leaking
1242          * information via timing (eg if the PAM config has a delay on fail).
1243          */
1244         if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1245             options.permit_root_login != PERMIT_YES))
1246                 sshpam_password = fake = fake_password(password);
1247
1248         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1249             (const void *)&passwd_conv);
1250         if (sshpam_err != PAM_SUCCESS)
1251                 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1252                     pam_strerror(sshpam_handle, sshpam_err));
1253
1254         sshpam_err = pam_authenticate(sshpam_handle, flags);
1255         sshpam_password = NULL;
1256         free(fake);
1257         if (sshpam_err == PAM_MAXTRIES)
1258                 sshpam_set_maxtries_reached(1);
1259         if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1260                 debug("PAM: password authentication accepted for %.100s",
1261                     authctxt->user);
1262                 return 1;
1263         } else {
1264                 debug("PAM: password authentication failed for %.100s: %s",
1265                     authctxt->valid ? authctxt->user : "an illegal user",
1266                     pam_strerror(sshpam_handle, sshpam_err));
1267                 return 0;
1268         }
1269 }
1270
1271 int
1272 sshpam_get_maxtries_reached(void)
1273 {
1274         return sshpam_maxtries_reached;
1275 }
1276
1277 void
1278 sshpam_set_maxtries_reached(int reached)
1279 {
1280         if (reached == 0 || sshpam_maxtries_reached)
1281                 return;
1282         sshpam_maxtries_reached = 1;
1283         options.password_authentication = 0;
1284         options.kbd_interactive_authentication = 0;
1285         options.challenge_response_authentication = 0;
1286 }
1287 #endif /* USE_PAM */