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) 2003,2004,2006 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 Exp $ */
  49 #include "includes.h"
  50
  51 #include <sys/types.h>
  52 #include <sys/stat.h>
  53 #include <sys/wait.h>
  54
  55 #include <errno.h>
  56 #include <signal.h>
  57 #include <stdarg.h>
  58 #include <string.h>
  59 #include <unistd.h>
  60
  61 #ifdef USE_PAM
  62 #if defined(HAVE_SECURITY_PAM_APPL_H)
  63 #include <security/pam_appl.h>
  64 #elif defined (HAVE_PAM_PAM_APPL_H)
  65 #include <pam/pam_appl.h>
  66 #endif
  67
  68 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */
  69 #ifdef PAM_SUN_CODEBASE
  70 # define sshpam_const           /* Solaris, HP-UX, AIX */
  71 #else
  72 # define sshpam_const   const   /* LinuxPAM, OpenPAM */
  73 #endif
  74
  75 /* Ambiguity in spec: is it an array of pointers or a pointer to an array? */
  76 #ifdef PAM_SUN_CODEBASE
  77 # define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member)
  78 #else
  79 # define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member)
  80 #endif
  81
  82 #include "xmalloc.h"
  83 #include "buffer.h"
  84 #include "key.h"
  85 #include "hostfile.h"
  86 #include "auth.h"
  87 #include "auth-pam.h"
  88 #include "canohost.h"
  89 #include "log.h"
  90 #include "msg.h"
  91 #include "packet.h"
  92 #include "misc.h"
  93 #include "servconf.h"
  94 #include "ssh2.h"
  95 #include "auth-options.h"
  96 #ifdef GSSAPI
  97 #include "ssh-gss.h"
  98 #endif
  99 #include "monitor_wrap.h"
 100
 101 extern ServerOptions options;
 102 extern Buffer loginmsg;
 103 extern int compat20;
 104 extern u_int utmp_len;
 105
 106 /* so we don't silently change behaviour */
 107 #ifdef USE_POSIX_THREADS
 108 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
 109 #endif
 110
 111 /*
 112  * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
 113  * and generally a bad idea.  Use at own risk and do not expect support if
 114  * this breaks.
 115  */
 116 #ifdef UNSUPPORTED_POSIX_THREADS_HACK
 117 #include <pthread.h>
 118 /*
 119  * Avoid namespace clash when *not* using pthreads for systems *with*
 120  * pthreads, which unconditionally define pthread_t via sys/types.h
 121  * (e.g. Linux)
 122  */
 123 typedef pthread_t sp_pthread_t;
 124 #else
 125 typedef pid_t sp_pthread_t;
 126 #endif
 127
 128 struct pam_ctxt {
 129         sp_pthread_t     pam_thread;
 130         int              pam_psock;
 131         int              pam_csock;
 132         int              pam_done;
 133 };
 134
 135 static void sshpam_free_ctx(void *);
 136 static struct pam_ctxt *cleanup_ctxt;
 137
 138 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 139 /*
 140  * Simulate threads with processes.
 141  */
 142
 143 static int sshpam_thread_status = -1;
 144 static mysig_t sshpam_oldsig;
 145
 146 static void
 147 sshpam_sigchld_handler(int sig)
 148 {
 149         signal(SIGCHLD, SIG_DFL);
 150         if (cleanup_ctxt == NULL)
 151                 return; /* handler called after PAM cleanup, shouldn't happen */
 152         if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
 153             <= 0) {
 154                 /* PAM thread has not exitted, privsep slave must have */
 155                 kill(cleanup_ctxt->pam_thread, SIGTERM);
 156                 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0)
 157                     <= 0)
 158                         return; /* could not wait */
 159         }
 160         if (WIFSIGNALED(sshpam_thread_status) &&
 161             WTERMSIG(sshpam_thread_status) == SIGTERM)
 162                 return; /* terminated by pthread_cancel */
 163         if (!WIFEXITED(sshpam_thread_status))
 164                 sigdie("PAM: authentication thread exited unexpectedly");
 165         if (WEXITSTATUS(sshpam_thread_status) != 0)
 166                 sigdie("PAM: authentication thread exited uncleanly");
 167 }
 168
 169 /* ARGSUSED */
 170 static void
 171 pthread_exit(void *value)
 172 {
 173         _exit(0);
 174 }
 175
 176 /* ARGSUSED */
 177 static int
 178 pthread_create(sp_pthread_t *thread, const void *attr,
 179     void *(*thread_start)(void *), void *arg)
 180 {
 181         pid_t pid;
 182         struct pam_ctxt *ctx = arg;
 183
 184         sshpam_thread_status = -1;
 185         switch ((pid = fork())) {
 186         case -1:
 187                 error("fork(): %s", strerror(errno));
 188                 return (-1);
 189         case 0:
 190                 close(ctx->pam_psock);
 191                 ctx->pam_psock = -1;
 192                 thread_start(arg);
 193                 _exit(1);
 194         default:
 195                 *thread = pid;
 196                 close(ctx->pam_csock);
 197                 ctx->pam_csock = -1;
 198                 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
 199                 return (0);
 200         }
 201 }
 202
 203 static int
 204 pthread_cancel(sp_pthread_t thread)
 205 {
 206         signal(SIGCHLD, sshpam_oldsig);
 207         return (kill(thread, SIGTERM));
 208 }
 209
 210 /* ARGSUSED */
 211 static int
 212 pthread_join(sp_pthread_t thread, void **value)
 213 {
 214         int status;
 215
 216         if (sshpam_thread_status != -1)
 217                 return (sshpam_thread_status);
 218         signal(SIGCHLD, sshpam_oldsig);
 219         waitpid(thread, &status, 0);
 220         return (status);
 221 }
 222 #endif
 223
 224
 225 static pam_handle_t *sshpam_handle = NULL;
 226 static int sshpam_err = 0;
 227 static int sshpam_authenticated = 0;
 228 static int sshpam_session_open = 0;
 229 static int sshpam_cred_established = 0;
 230 static int sshpam_account_status = -1;
 231 static char **sshpam_env = NULL;
 232 static Authctxt *sshpam_authctxt = NULL;
 233 static const char *sshpam_password = NULL;
 234 static char badpw[] = "\b\n\r\177INCORRECT";
 235
 236 /* Some PAM implementations don't implement this */
 237 #ifndef HAVE_PAM_GETENVLIST
 238 static char **
 239 pam_getenvlist(pam_handle_t *pamh)
 240 {
 241         /*
 242          * XXX - If necessary, we can still support envrionment passing
 243          * for platforms without pam_getenvlist by searching for known
 244          * env vars (e.g. KRB5CCNAME) from the PAM environment.
 245          */
 246          return NULL;
 247 }
 248 #endif
 249
 250 /*
 251  * Some platforms, notably Solaris, do not enforce password complexity
 252  * rules during pam_chauthtok() if the real uid of the calling process
 253  * is 0, on the assumption that it's being called by "passwd" run by root.
 254  * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
 255  * the right thing.
 256  */
 257 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
 258 static int
 259 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
 260 {
 261         int result;
 262
 263         if (sshpam_authctxt == NULL)
 264                 fatal("PAM: sshpam_authctxt not initialized");
 265         if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
 266                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 267         result = pam_chauthtok(pamh, flags);
 268         if (setreuid(0, -1) == -1)
 269                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 270         return result;
 271 }
 272 # define pam_chauthtok(a,b)     (sshpam_chauthtok_ruid((a), (b)))
 273 #endif
 274
 275 struct passwd *
 276 sshpam_getpw(const char *user)
 277 {
 278         struct passwd *pw;
 279
 280         if ((pw = getpwnam(user)) != NULL)
 281                 return(pw);
 282
 283         debug("PAM: faking passwd struct for user '%.100s'", user);
 284         if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
 285                 return NULL;
 286         pw->pw_name = xstrdup(user);    /* XXX leak */
 287         pw->pw_shell = "/bin/true";
 288         pw->pw_gecos = "sshd fake PAM user";
 289         return (pw);
 290 }
 291
 292 void
 293 sshpam_check_userchanged(void)
 294 {
 295         int sshpam_err;
 296         struct passwd *pw;
 297         const char *user;
 298
 299         debug("sshpam_check_userchanged");
 300         sshpam_err = pam_get_item(sshpam_handle, PAM_USER, &user);
 301         if (sshpam_err != PAM_SUCCESS)
 302                 fatal("PAM: could not get PAM_USER: %s",
 303                     pam_strerror(sshpam_handle, sshpam_err));
 304         if (strcmp(user, sshpam_authctxt->pw->pw_name) != 0) {
 305                 debug("PAM: user mapped from '%.100s' to '%.100s'",
 306                     sshpam_authctxt->pw->pw_name, user);
 307                 if ((pw = getpwnam(user)) == NULL)
 308                         fatal("PAM: could not get passwd entry for user "
 309                             "'%.100s' provided by PAM_USER", user);
 310                 pwfree(sshpam_authctxt->pw);
 311                 sshpam_authctxt->pw = pw;
 312                 sshpam_authctxt->valid = allowed_user(pw);
 313                 debug("PAM: user '%.100s' now %svalid", user,
 314                     sshpam_authctxt->valid ? "" : "in");
 315         }
 316 }
 317
 318 void
 319 sshpam_password_change_required(int reqd)
 320 {
 321         debug3("%s %d", __func__, reqd);
 322         if (sshpam_authctxt == NULL)
 323                 fatal("%s: PAM authctxt not initialized", __func__);
 324         sshpam_authctxt->force_pwchange = reqd;
 325         if (reqd) {
 326                 no_port_forwarding_flag |= 2;
 327                 no_agent_forwarding_flag |= 2;
 328                 no_x11_forwarding_flag |= 2;
 329         } else {
 330                 no_port_forwarding_flag &= ~2;
 331                 no_agent_forwarding_flag &= ~2;
 332                 no_x11_forwarding_flag &= ~2;
 333         }
 334 }
 335
 336 /* Import regular and PAM environment from subprocess */
 337 static void
 338 import_environments(Buffer *b)
 339 {
 340         char *env, *user;
 341         u_int i, num_env;
 342         int err;
 343
 344         debug3("PAM: %s entering", __func__);
 345
 346 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 347         /* Import variables set by do_pam_account */
 348         sshpam_account_status = buffer_get_int(b);
 349         sshpam_password_change_required(buffer_get_int(b));
 350         if (options.permit_pam_user_change) {
 351         user = buffer_get_string(b, NULL);
 352         debug("PAM: got username '%.100s' from thread", user);
 353         if ((err = pam_set_item(sshpam_handle, PAM_USER, user)) != PAM_SUCCESS)
 354             fatal("PAM: failed to set PAM_USER: %s",
 355                   pam_strerror(sshpam_handle, err));
 356         pwfree(sshpam_authctxt->pw);
 357         sshpam_authctxt->pw = pwcopy(sshpam_getpw(user));
 358     }
 359
 360         /* Import environment from subprocess */
 361         num_env = buffer_get_int(b);
 362         if (num_env > 1024)
 363                 fatal("%s: received %u environment variables, expected <= 1024",
 364                     __func__, num_env);
 365         sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env));
 366         debug3("PAM: num env strings %d", num_env);
 367         for(i = 0; i < num_env; i++)
 368                 sshpam_env[i] = buffer_get_string(b, NULL);
 369
 370         sshpam_env[num_env] = NULL;
 371
 372         /* Import PAM environment from subprocess */
 373         num_env = buffer_get_int(b);
 374         debug("PAM: num PAM env strings %d", num_env);
 375         for(i = 0; i < num_env; i++) {
 376                 env = buffer_get_string(b, NULL);
 377
 378 #ifdef HAVE_PAM_PUTENV
 379                 /* Errors are not fatal here */
 380                 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
 381                         error("PAM: pam_putenv: %s",
 382                             pam_strerror(sshpam_handle, sshpam_err));
 383                 }
 384 #endif
 385         }
 386 #endif
 387 }
 388
 389 /*
 390  * Conversation function for authentication thread.
 391  */
 392 static int
 393 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
 394     struct pam_response **resp, void *data)
 395 {
 396         Buffer buffer;
 397         struct pam_ctxt *ctxt;
 398         struct pam_response *reply;
 399         int i;
 400
 401         debug3("PAM: %s entering, %d messages", __func__, n);
 402         *resp = NULL;
 403
 404         if (data == NULL) {
 405                 error("PAM: conversation function passed a null context");
 406                 return (PAM_CONV_ERR);
 407         }
 408         ctxt = data;
 409         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 410                 return (PAM_CONV_ERR);
 411
 412         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 413                 return (PAM_CONV_ERR);
 414
 415         buffer_init(&buffer);
 416         for (i = 0; i < n; ++i) {
 417                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 418                 case PAM_PROMPT_ECHO_OFF:
 419                         buffer_put_cstring(&buffer,
 420                             PAM_MSG_MEMBER(msg, i, msg));
 421                         if (ssh_msg_send(ctxt->pam_csock,
 422                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 423                                 goto fail;
 424                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 425                                 goto fail;
 426                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 427                                 goto fail;
 428                         reply[i].resp = buffer_get_string(&buffer, NULL);
 429                         break;
 430                 case PAM_PROMPT_ECHO_ON:
 431                         buffer_put_cstring(&buffer,
 432                             PAM_MSG_MEMBER(msg, i, msg));
 433                         if (ssh_msg_send(ctxt->pam_csock,
 434                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 435                                 goto fail;
 436                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 437                                 goto fail;
 438                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 439                                 goto fail;
 440                         reply[i].resp = buffer_get_string(&buffer, NULL);
 441                         break;
 442                 case PAM_ERROR_MSG:
 443                         buffer_put_cstring(&buffer,
 444                             PAM_MSG_MEMBER(msg, i, msg));
 445                         if (ssh_msg_send(ctxt->pam_csock,
 446                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 447                                 goto fail;
 448                         break;
 449                 case PAM_TEXT_INFO:
 450                         buffer_put_cstring(&buffer,
 451                             PAM_MSG_MEMBER(msg, i, msg));
 452                         if (ssh_msg_send(ctxt->pam_csock,
 453                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 454                                 goto fail;
 455                         break;
 456                 default:
 457                         goto fail;
 458                 }
 459                 buffer_clear(&buffer);
 460         }
 461         buffer_free(&buffer);
 462         *resp = reply;
 463         return (PAM_SUCCESS);
 464
 465  fail:
 466         for(i = 0; i < n; i++) {
 467                 if (reply[i].resp != NULL)
 468                         xfree(reply[i].resp);
 469         }
 470         xfree(reply);
 471         buffer_free(&buffer);
 472         return (PAM_CONV_ERR);
 473 }
 474
 475 /*
 476  * Authentication thread.
 477  */
 478 static void *
 479 sshpam_thread(void *ctxtp)
 480 {
 481         struct pam_ctxt *ctxt = ctxtp;
 482         Buffer buffer;
 483         struct pam_conv sshpam_conv;
 484         int flags = (options.permit_empty_passwd == 0 ?
 485             PAM_DISALLOW_NULL_AUTHTOK : 0);
 486 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 487         extern char **environ;
 488         char **env_from_pam;
 489         u_int i;
 490         const char *pam_user;
 491         const char **ptr_pam_user = &pam_user;
 492         char *tz = getenv("TZ");
 493
 494         pam_get_item(sshpam_handle, PAM_USER,
 495             (sshpam_const void **)ptr_pam_user);
 496
 497         environ[0] = NULL;
 498         if (tz != NULL)
 499                 if (setenv("TZ", tz, 1) == -1)
 500                         error("PAM: could not set TZ environment: %s",
 501                             strerror(errno));
 502
 503         if (sshpam_authctxt != NULL) {
 504                 setproctitle("%s [pam]",
 505                     sshpam_authctxt->valid ? pam_user : "unknown");
 506         }
 507 #endif
 508
 509         sshpam_conv.conv = sshpam_thread_conv;
 510         sshpam_conv.appdata_ptr = ctxt;
 511
 512         if (sshpam_authctxt == NULL)
 513                 fatal("%s: PAM authctxt not initialized", __func__);
 514
 515         buffer_init(&buffer);
 516         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 517             (const void *)&sshpam_conv);
 518         if (sshpam_err != PAM_SUCCESS)
 519                 goto auth_fail;
 520         sshpam_err = pam_authenticate(sshpam_handle, flags);
 521         if (sshpam_err != PAM_SUCCESS)
 522                 goto auth_fail;
 523
 524         if (options.permit_pam_user_change) {
 525         sshpam_check_userchanged();
 526     }
 527         if (compat20) {
 528                 if (!do_pam_account()) {
 529                         sshpam_err = PAM_ACCT_EXPIRED;
 530                         goto auth_fail;
 531                 }
 532                 if (sshpam_authctxt->force_pwchange) {
 533                         sshpam_err = pam_chauthtok(sshpam_handle,
 534                             PAM_CHANGE_EXPIRED_AUTHTOK);
 535                         if (sshpam_err != PAM_SUCCESS)
 536                                 goto auth_fail;
 537                         sshpam_password_change_required(0);
 538                 }
 539         }
 540
 541         buffer_put_cstring(&buffer, "OK");
 542
 543 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 544         /* Export variables set by do_pam_account */
 545         buffer_put_int(&buffer, sshpam_account_status);
 546         buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);
 547         if (options.permit_pam_user_change) {
 548         buffer_put_cstring(&buffer, sshpam_authctxt->pw->pw_name);
 549     }
 550
 551         /* Export any environment strings set in child */
 552         for(i = 0; environ[i] != NULL; i++)
 553                 ; /* Count */
 554         buffer_put_int(&buffer, i);
 555         for(i = 0; environ[i] != NULL; i++)
 556                 buffer_put_cstring(&buffer, environ[i]);
 557
 558         /* Export any environment strings set by PAM in child */
 559         env_from_pam = pam_getenvlist(sshpam_handle);
 560         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 561                 ; /* Count */
 562         buffer_put_int(&buffer, i);
 563         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 564                 buffer_put_cstring(&buffer, env_from_pam[i]);
 565 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */
 566
 567         /* XXX - can't do much about an error here */
 568         ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
 569         buffer_free(&buffer);
 570         pthread_exit(NULL);
 571
 572  auth_fail:
 573         buffer_put_cstring(&buffer,
 574             pam_strerror(sshpam_handle, sshpam_err));
 575         /* XXX - can't do much about an error here */
 576         if (sshpam_err == PAM_ACCT_EXPIRED)
 577                 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, &buffer);
 578         else
 579                 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
 580         buffer_free(&buffer);
 581         pthread_exit(NULL);
 582
 583         return (NULL); /* Avoid warning for non-pthread case */
 584 }
 585
 586 void
 587 sshpam_thread_cleanup(void)
 588 {
 589         struct pam_ctxt *ctxt = cleanup_ctxt;
 590
 591         debug3("PAM: %s entering", __func__);
 592         if (ctxt != NULL && ctxt->pam_thread != 0) {
 593                 pthread_cancel(ctxt->pam_thread);
 594                 pthread_join(ctxt->pam_thread, NULL);
 595                 close(ctxt->pam_psock);
 596                 close(ctxt->pam_csock);
 597                 memset(ctxt, 0, sizeof(*ctxt));
 598                 cleanup_ctxt = NULL;
 599         }
 600 }
 601
 602 static int
 603 sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
 604     struct pam_response **resp, void *data)
 605 {
 606         debug3("PAM: %s entering, %d messages", __func__, n);
 607         return (PAM_CONV_ERR);
 608 }
 609
 610 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
 611
 612 static int
 613 sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
 614     struct pam_response **resp, void *data)
 615 {
 616         struct pam_response *reply;
 617         int i;
 618         size_t len;
 619
 620         debug3("PAM: %s called with %d messages", __func__, n);
 621         *resp = NULL;
 622
 623         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 624                 return (PAM_CONV_ERR);
 625
 626         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 627                 return (PAM_CONV_ERR);
 628
 629         for (i = 0; i < n; ++i) {
 630                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 631                 case PAM_ERROR_MSG:
 632                 case PAM_TEXT_INFO:
 633                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
 634                         buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
 635                         buffer_append(&loginmsg, "\n", 1 );
 636                         reply[i].resp_retcode = PAM_SUCCESS;
 637                         break;
 638                 default:
 639                         goto fail;
 640                 }
 641         }
 642         *resp = reply;
 643         return (PAM_SUCCESS);
 644
 645  fail:
 646         for(i = 0; i < n; i++) {
 647                 if (reply[i].resp != NULL)
 648                         xfree(reply[i].resp);
 649         }
 650         xfree(reply);
 651         return (PAM_CONV_ERR);
 652 }
 653
 654 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
 655
 656 void
 657 sshpam_cleanup(void)
 658 {
 659         if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor()))
 660                 return;
 661         debug("PAM: cleanup");
 662         pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 663         if (sshpam_session_open) {
 664                 debug("PAM: closing session");
 665                 pam_close_session(sshpam_handle, PAM_SILENT);
 666                 sshpam_session_open = 0;
 667         }
 668         if (sshpam_cred_established) {
 669                 debug("PAM: deleting credentials");
 670                 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
 671                 sshpam_cred_established = 0;
 672         }
 673         sshpam_authenticated = 0;
 674         pam_end(sshpam_handle, sshpam_err);
 675         sshpam_handle = NULL;
 676 }
 677
 678 static int
 679 sshpam_init(Authctxt *authctxt)
 680 {
 681         extern char *__progname;
 682         const char *pam_rhost, *pam_user, *user = authctxt->user;
 683         const char **ptr_pam_user = &pam_user;
 684
 685         if (sshpam_handle != NULL) {
 686                 /* We already have a PAM context; check if the user matches */
 687                 sshpam_err = pam_get_item(sshpam_handle,
 688                     PAM_USER, (sshpam_const void **)ptr_pam_user);
 689                 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
 690                         return (0);
 691                 pam_end(sshpam_handle, sshpam_err);
 692                 sshpam_handle = NULL;
 693         }
 694         debug("PAM: initializing for \"%s\"", user);
 695         sshpam_err =
 696             pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
 697         sshpam_authctxt = authctxt;
 698
 699         if (sshpam_err != PAM_SUCCESS) {
 700                 pam_end(sshpam_handle, sshpam_err);
 701                 sshpam_handle = NULL;
 702                 return (-1);
 703         }
 704         pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
 705         debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
 706         sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
 707         if (sshpam_err != PAM_SUCCESS) {
 708                 pam_end(sshpam_handle, sshpam_err);
 709                 sshpam_handle = NULL;
 710                 return (-1);
 711         }
 712 #ifdef PAM_TTY_KLUDGE
 713         /*
 714          * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
 715          * sshd doesn't set the tty until too late in the auth process and
 716          * may not even set one (for tty-less connections)
 717          */
 718         debug("PAM: setting PAM_TTY to \"ssh\"");
 719         sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
 720         if (sshpam_err != PAM_SUCCESS) {
 721                 pam_end(sshpam_handle, sshpam_err);
 722                 sshpam_handle = NULL;
 723                 return (-1);
 724         }
 725 #endif
 726         return (0);
 727 }
 728
 729 static void *
 730 sshpam_init_ctx(Authctxt *authctxt)
 731 {
 732         struct pam_ctxt *ctxt;
 733         int socks[2];
 734
 735         debug3("PAM: %s entering", __func__);
 736         /*
 737          * Refuse to start if we don't have PAM enabled or do_pam_account
 738          * has previously failed.
 739          */
 740         if (!options.use_pam || sshpam_account_status == 0)
 741                 return NULL;
 742
 743         /* Initialize PAM */
 744         if (sshpam_init(authctxt) == -1) {
 745                 error("PAM: initialization failed");
 746                 return (NULL);
 747         }
 748
 749         ctxt = xcalloc(1, sizeof *ctxt);
 750
 751         /* Start the authentication thread */
 752         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
 753                 error("PAM: failed create sockets: %s", strerror(errno));
 754                 xfree(ctxt);
 755                 return (NULL);
 756         }
 757         ctxt->pam_psock = socks[0];
 758         ctxt->pam_csock = socks[1];
 759         if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
 760                 error("PAM: failed to start authentication thread: %s",
 761                     strerror(errno));
 762                 close(socks[0]);
 763                 close(socks[1]);
 764                 xfree(ctxt);
 765                 return (NULL);
 766         }
 767         cleanup_ctxt = ctxt;
 768         return (ctxt);
 769 }
 770
 771 static int
 772 sshpam_query(void *ctx, char **name, char **info,
 773     u_int *num, char ***prompts, u_int **echo_on)
 774 {
 775         Buffer buffer;
 776         struct pam_ctxt *ctxt = ctx;
 777         size_t plen;
 778         u_char type;
 779         char *msg;
 780         size_t len, mlen;
 781
 782         debug3("PAM: %s entering", __func__);
 783         buffer_init(&buffer);
 784         *name = xstrdup("");
 785         *info = xstrdup("");
 786         *prompts = xmalloc(sizeof(char *));
 787         **prompts = NULL;
 788         plen = 0;
 789         *echo_on = xmalloc(sizeof(u_int));
 790         while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
 791                 type = buffer_get_char(&buffer);
 792                 msg = buffer_get_string(&buffer, NULL);
 793                 mlen = strlen(msg);
 794                 switch (type) {
 795                 case PAM_PROMPT_ECHO_ON:
 796                 case PAM_PROMPT_ECHO_OFF:
 797                         *num = 1;
 798                         len = plen + mlen + 1;
 799                         **prompts = xrealloc(**prompts, 1, len);
 800                         strlcpy(**prompts + plen, msg, len - plen);
 801                         plen += mlen;
 802                         **echo_on = (type == PAM_PROMPT_ECHO_ON);
 803                         xfree(msg);
 804                         return (0);
 805                 case PAM_ERROR_MSG:
 806                 case PAM_TEXT_INFO:
 807                         /* accumulate messages */
 808                         len = plen + mlen + 2;
 809                         **prompts = xrealloc(**prompts, 1, len);
 810                         strlcpy(**prompts + plen, msg, len - plen);
 811                         plen += mlen;
 812                         strlcat(**prompts + plen, "\n", len - plen);
 813                         plen++;
 814                         xfree(msg);
 815                         break;
 816                 case PAM_ACCT_EXPIRED:
 817                         sshpam_account_status = 0;
 818                         /* FALLTHROUGH */
 819                 case PAM_AUTH_ERR:
 820                         debug3("PAM: %s", pam_strerror(sshpam_handle, type));
 821                         if (**prompts != NULL && strlen(**prompts) != 0) {
 822                                 *info = **prompts;
 823                                 **prompts = NULL;
 824                                 *num = 0;
 825                                 **echo_on = 0;
 826                                 ctxt->pam_done = -1;
 827                                 xfree(msg);
 828                                 return 0;
 829                         }
 830                         /* FALLTHROUGH */
 831                 case PAM_SUCCESS:
 832                         if (**prompts != NULL) {
 833                                 /* drain any accumulated messages */
 834                                 debug("PAM: %s", **prompts);
 835                                 buffer_append(&loginmsg, **prompts,
 836                                     strlen(**prompts));
 837                                 xfree(**prompts);
 838                                 **prompts = NULL;
 839                         }
 840                         if (type == PAM_SUCCESS) {
 841                                 if (!sshpam_authctxt->valid ||
 842                                     (sshpam_authctxt->pw->pw_uid == 0 &&
 843                                     options.permit_root_login != PERMIT_YES))
 844                                         fatal("Internal error: PAM auth "
 845                                             "succeeded when it should have "
 846                                             "failed");
 847                                 import_environments(&buffer);
 848                                 *num = 0;
 849                                 **echo_on = 0;
 850                                 ctxt->pam_done = 1;
 851                                 xfree(msg);
 852                                 return (0);
 853                         }
 854                         error("PAM: %s for %s%.100s from %.100s", msg,
 855                             sshpam_authctxt->valid ? "" : "illegal user ",
 856                             sshpam_authctxt->user,
 857                             get_remote_name_or_ip(utmp_len, options.use_dns));
 858                         /* FALLTHROUGH */
 859                 default:
 860                         *num = 0;
 861                         **echo_on = 0;
 862                         xfree(msg);
 863                         ctxt->pam_done = -1;
 864                         return (-1);
 865                 }
 866         }
 867         return (-1);
 868 }
 869
 870 /* XXX - see also comment in auth-chall.c:verify_response */
 871 static int
 872 sshpam_respond(void *ctx, u_int num, char **resp)
 873 {
 874         Buffer buffer;
 875         struct pam_ctxt *ctxt = ctx;
 876
 877         debug2("PAM: %s entering, %u responses", __func__, num);
 878         switch (ctxt->pam_done) {
 879         case 1:
 880                 sshpam_authenticated = 1;
 881                 return (0);
 882         case 0:
 883                 break;
 884         default:
 885                 return (-1);
 886         }
 887         if (num != 1) {
 888                 error("PAM: expected one response, got %u", num);
 889                 return (-1);
 890         }
 891         buffer_init(&buffer);
 892         if (sshpam_authctxt->valid &&
 893             (sshpam_authctxt->pw->pw_uid != 0 ||
 894             options.permit_root_login == PERMIT_YES))
 895                 buffer_put_cstring(&buffer, *resp);
 896         else
 897                 buffer_put_cstring(&buffer, badpw);
 898         if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
 899                 buffer_free(&buffer);
 900                 return (-1);
 901         }
 902         buffer_free(&buffer);
 903         return (1);
 904 }
 905
 906 static void
 907 sshpam_free_ctx(void *ctxtp)
 908 {
 909         struct pam_ctxt *ctxt = ctxtp;
 910
 911         debug3("PAM: %s entering", __func__);
 912         sshpam_thread_cleanup();
 913         xfree(ctxt);
 914         /*
 915          * We don't call sshpam_cleanup() here because we may need the PAM
 916          * handle at a later stage, e.g. when setting up a session.  It's
 917          * still on the cleanup list, so pam_end() *will* be called before
 918          * the server process terminates.
 919          */
 920 }
 921
 922 KbdintDevice sshpam_device = {
 923         "pam",
 924         sshpam_init_ctx,
 925         sshpam_query,
 926         sshpam_respond,
 927         sshpam_free_ctx
 928 };
 929
 930 KbdintDevice mm_sshpam_device = {
 931         "pam",
 932         mm_sshpam_init_ctx,
 933         mm_sshpam_query,
 934         mm_sshpam_respond,
 935         mm_sshpam_free_ctx
 936 };
 937
 938 /*
 939  * This replaces auth-pam.c
 940  */
 941 void
 942 start_pam(Authctxt *authctxt)
 943 {
 944         if (!options.use_pam)
 945                 fatal("PAM: initialisation requested when UsePAM=no");
 946
 947         if (sshpam_init(authctxt) == -1)
 948                 fatal("PAM: initialisation failed");
 949 }
 950
 951 void
 952 finish_pam(void)
 953 {
 954         sshpam_cleanup();
 955 }
 956
 957 u_int
 958 do_pam_account(void)
 959 {
 960         debug("%s: called", __func__);
 961         if (sshpam_account_status != -1)
 962                 return (sshpam_account_status);
 963
 964         sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
 965         debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
 966             pam_strerror(sshpam_handle, sshpam_err));
 967
 968         if (options.permit_pam_user_change) {
 969         sshpam_check_userchanged();
 970         if (getpwnam(sshpam_authctxt->pw->pw_name) == NULL)
 971             fatal("PAM: completed authentication but PAM account invalid");
 972     }
 973
 974         if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
 975                 sshpam_account_status = 0;
 976                 return (sshpam_account_status);
 977         }
 978
 979         if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
 980                 sshpam_password_change_required(1);
 981
 982         sshpam_account_status = 1;
 983         return (sshpam_account_status);
 984 }
 985
 986 void
 987 do_pam_set_tty(const char *tty)
 988 {
 989         if (tty != NULL) {
 990                 debug("PAM: setting PAM_TTY to \"%s\"", tty);
 991                 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
 992                 if (sshpam_err != PAM_SUCCESS)
 993                         fatal("PAM: failed to set PAM_TTY: %s",
 994                             pam_strerror(sshpam_handle, sshpam_err));
 995         }
 996 }
 997
 998 void
 999 do_pam_setcred(int init)
1000 {
1001         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1002             (const void *)&store_conv);
1003         if (sshpam_err != PAM_SUCCESS)
1004                 fatal("PAM: failed to set PAM_CONV: %s",
1005                     pam_strerror(sshpam_handle, sshpam_err));
1006         if (init) {
1007                 debug("PAM: establishing credentials");
1008                 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
1009         } else {
1010                 debug("PAM: reinitializing credentials");
1011                 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
1012         }
1013         if (sshpam_err == PAM_SUCCESS) {
1014                 sshpam_cred_established = 1;
1015                 return;
1016         }
1017         if (sshpam_authenticated)
1018                 fatal("PAM: pam_setcred(): %s",
1019                     pam_strerror(sshpam_handle, sshpam_err));
1020         else
1021                 debug("PAM: pam_setcred(): %s",
1022                     pam_strerror(sshpam_handle, sshpam_err));
1023 }
1024
1025 static int
1026 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
1027     struct pam_response **resp, void *data)
1028 {
1029         char input[PAM_MAX_MSG_SIZE];
1030         struct pam_response *reply;
1031         int i;
1032
1033         debug3("PAM: %s called with %d messages", __func__, n);
1034
1035         *resp = NULL;
1036
1037         if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
1038                 return (PAM_CONV_ERR);
1039
1040         if ((reply = calloc(n, sizeof(*reply))) == NULL)
1041                 return (PAM_CONV_ERR);
1042
1043         for (i = 0; i < n; ++i) {
1044                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1045                 case PAM_PROMPT_ECHO_OFF:
1046                         reply[i].resp =
1047                             read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
1048                             RP_ALLOW_STDIN);
1049                         reply[i].resp_retcode = PAM_SUCCESS;
1050                         break;
1051                 case PAM_PROMPT_ECHO_ON:
1052                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1053                         if (fgets(input, sizeof input, stdin) == NULL)
1054                                 input[0] = '\0';
1055                         if ((reply[i].resp = strdup(input)) == NULL)
1056                                 goto fail;
1057                         reply[i].resp_retcode = PAM_SUCCESS;
1058                         break;
1059                 case PAM_ERROR_MSG:
1060                 case PAM_TEXT_INFO:
1061                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1062                         reply[i].resp_retcode = PAM_SUCCESS;
1063                         break;
1064                 default:
1065                         goto fail;
1066                 }
1067         }
1068         *resp = reply;
1069         return (PAM_SUCCESS);
1070
1071  fail:
1072         for(i = 0; i < n; i++) {
1073                 if (reply[i].resp != NULL)
1074                         xfree(reply[i].resp);
1075         }
1076         xfree(reply);
1077         return (PAM_CONV_ERR);
1078 }
1079
1080 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
1081
1082 /*
1083  * XXX this should be done in the authentication phase, but ssh1 doesn't
1084  * support that
1085  */
1086 void
1087 do_pam_chauthtok(void)
1088 {
1089         if (use_privsep)
1090                 fatal("Password expired (unable to change with privsep)");
1091         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1092             (const void *)&tty_conv);
1093         if (sshpam_err != PAM_SUCCESS)
1094                 fatal("PAM: failed to set PAM_CONV: %s",
1095                     pam_strerror(sshpam_handle, sshpam_err));
1096         debug("PAM: changing password");
1097         sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
1098         if (sshpam_err != PAM_SUCCESS)
1099                 fatal("PAM: pam_chauthtok(): %s",
1100                     pam_strerror(sshpam_handle, sshpam_err));
1101 }
1102
1103 void
1104 do_pam_session(void)
1105 {
1106         debug3("PAM: opening session");
1107         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1108             (const void *)&store_conv);
1109         if (sshpam_err != PAM_SUCCESS)
1110                 fatal("PAM: failed to set PAM_CONV: %s",
1111                     pam_strerror(sshpam_handle, sshpam_err));
1112         sshpam_err = pam_open_session(sshpam_handle, 0);
1113         if (sshpam_err == PAM_SUCCESS)
1114                 sshpam_session_open = 1;
1115         else {
1116                 sshpam_session_open = 0;
1117                 disable_forwarding();
1118                 error("PAM: pam_open_session(): %s",
1119                     pam_strerror(sshpam_handle, sshpam_err));
1120         }
1121
1122 }
1123
1124 int
1125 is_pam_session_open(void)
1126 {
1127         return sshpam_session_open;
1128 }
1129
1130 /*
1131  * Set a PAM environment string. We need to do this so that the session
1132  * modules can handle things like Kerberos/GSI credentials that appear
1133  * during the ssh authentication process.
1134  */
1135 int
1136 do_pam_putenv(char *name, char *value)
1137 {
1138         int ret = 1;
1139 #ifdef HAVE_PAM_PUTENV
1140         char *compound;
1141         size_t len;
1142
1143         len = strlen(name) + strlen(value) + 2;
1144         compound = xmalloc(len);
1145
1146         snprintf(compound, len, "%s=%s", name, value);
1147         ret = pam_putenv(sshpam_handle, compound);
1148         xfree(compound);
1149 #endif
1150
1151         return (ret);
1152 }
1153
1154 char **
1155 fetch_pam_child_environment(void)
1156 {
1157         return sshpam_env;
1158 }
1159
1160 char **
1161 fetch_pam_environment(void)
1162 {
1163         return (pam_getenvlist(sshpam_handle));
1164 }
1165
1166 void
1167 free_pam_environment(char **env)
1168 {
1169         char **envp;
1170
1171         if (env == NULL)
1172                 return;
1173
1174         for (envp = env; *envp; envp++)
1175                 xfree(*envp);
1176         xfree(env);
1177 }
1178
1179 /*
1180  * "Blind" conversation function for password authentication.  Assumes that
1181  * echo-off prompts are for the password and stores messages for later
1182  * display.
1183  */
1184 static int
1185 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1186     struct pam_response **resp, void *data)
1187 {
1188         struct pam_response *reply;
1189         int i;
1190         size_t len;
1191
1192         debug3("PAM: %s called with %d messages", __func__, n);
1193
1194         *resp = NULL;
1195
1196         if (n <= 0 || n > PAM_MAX_NUM_MSG)
1197                 return (PAM_CONV_ERR);
1198
1199         if ((reply = calloc(n, sizeof(*reply))) == NULL)
1200                 return (PAM_CONV_ERR);
1201
1202         for (i = 0; i < n; ++i) {
1203                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1204                 case PAM_PROMPT_ECHO_OFF:
1205                         if (sshpam_password == NULL)
1206                                 goto fail;
1207                         if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1208                                 goto fail;
1209                         reply[i].resp_retcode = PAM_SUCCESS;
1210                         break;
1211                 case PAM_ERROR_MSG:
1212                 case PAM_TEXT_INFO:
1213                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1214                         if (len > 0) {
1215                                 buffer_append(&loginmsg,
1216                                     PAM_MSG_MEMBER(msg, i, msg), len);
1217                                 buffer_append(&loginmsg, "\n", 1);
1218                         }
1219                         if ((reply[i].resp = strdup("")) == NULL)
1220                                 goto fail;
1221                         reply[i].resp_retcode = PAM_SUCCESS;
1222                         break;
1223                 default:
1224                         goto fail;
1225                 }
1226         }
1227         *resp = reply;
1228         return (PAM_SUCCESS);
1229
1230  fail:
1231         for(i = 0; i < n; i++) {
1232                 if (reply[i].resp != NULL)
1233                         xfree(reply[i].resp);
1234         }
1235         xfree(reply);
1236         return (PAM_CONV_ERR);
1237 }
1238
1239 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1240
1241 /*
1242  * Attempt password authentication via PAM
1243  */
1244 int
1245 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1246 {
1247         int flags = (options.permit_empty_passwd == 0 ?
1248             PAM_DISALLOW_NULL_AUTHTOK : 0);
1249
1250         if (!options.use_pam || sshpam_handle == NULL)
1251                 fatal("PAM: %s called when PAM disabled or failed to "
1252                     "initialise.", __func__);
1253
1254         sshpam_password = password;
1255         sshpam_authctxt = authctxt;
1256
1257         /*
1258          * If the user logging in is invalid, or is root but is not permitted
1259          * by PermitRootLogin, use an invalid password to prevent leaking
1260          * information via timing (eg if the PAM config has a delay on fail).
1261          */
1262         if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1263             options.permit_root_login != PERMIT_YES))
1264                 sshpam_password = badpw;
1265
1266         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1267             (const void *)&passwd_conv);
1268         if (sshpam_err != PAM_SUCCESS)
1269                 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1270                     pam_strerror(sshpam_handle, sshpam_err));
1271
1272         sshpam_err = pam_authenticate(sshpam_handle, flags);
1273         if (options.permit_pam_user_change) {
1274         sshpam_check_userchanged();
1275     }
1276         sshpam_password = NULL;
1277         if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1278                 debug("PAM: password authentication accepted for %.100s",
1279                     authctxt->user);
1280                 return 1;
1281         } else {
1282                 debug("PAM: password authentication failed for %.100s: %s",
1283                     authctxt->valid ? authctxt->user : "an illegal user",
1284                     pam_strerror(sshpam_handle, sshpam_err));
1285                 return 0;
1286         }
1287 }
1288 #endif /* USE_PAM */