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