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 /* Based on $FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des Exp $ */
  33 #include "includes.h"
  34 RCSID("$Id$");
  35
  36 #ifdef USE_PAM
  37 #if defined(HAVE_SECURITY_PAM_APPL_H)
  38 #include <security/pam_appl.h>
  39 #elif defined (HAVE_PAM_PAM_APPL_H)
  40 #include <pam/pam_appl.h>
  41 #endif
  42
  43 #include "auth.h"
  44 #include "auth-pam.h"
  45 #include "buffer.h"
  46 #include "bufaux.h"
  47 #include "canohost.h"
  48 #include "log.h"
  49 #include "monitor_wrap.h"
  50 #include "msg.h"
  51 #include "packet.h"
  52 #include "readpass.h"
  53 #include "servconf.h"
  54 #include "ssh2.h"
  55 #include "xmalloc.h"
  56 #include "auth-options.h"
  57
  58 extern ServerOptions options;
  59 extern Buffer loginmsg;
  60 extern int compat20;
  61
  62 #ifdef USE_POSIX_THREADS
  63 #include <pthread.h>
  64 /*
  65  * Avoid namespace clash when *not* using pthreads for systems *with*
  66  * pthreads, which unconditionally define pthread_t via sys/types.h
  67  * (e.g. Linux)
  68  */
  69 typedef pthread_t sp_pthread_t;
  70 #else
  71 typedef pid_t sp_pthread_t;
  72 #endif
  73
  74 struct pam_ctxt {
  75         sp_pthread_t     pam_thread;
  76         int              pam_psock;
  77         int              pam_csock;
  78         int              pam_done;
  79 };
  80
  81 static void sshpam_free_ctx(void *);
  82 static struct pam_ctxt *cleanup_ctxt;
  83
  84 #ifndef USE_POSIX_THREADS
  85 /*
  86  * Simulate threads with processes.
  87  */
  88
  89 static int sshpam_thread_status = -1;
  90 static mysig_t sshpam_oldsig;
  91
  92 static void
  93 sshpam_sigchld_handler(int sig)
  94 {
  95         if (cleanup_ctxt == NULL)
  96                 return; /* handler called after PAM cleanup, shouldn't happen */
  97         if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0) == -1)
  98                 return; /* couldn't wait for process */
  99         if (WIFSIGNALED(sshpam_thread_status) &&
 100             WTERMSIG(sshpam_thread_status) == SIGTERM)
 101                 return; /* terminated by pthread_cancel */
 102         if (!WIFEXITED(sshpam_thread_status))
 103                 fatal("PAM: authentication thread exited unexpectedly");
 104         if (WEXITSTATUS(sshpam_thread_status) != 0)
 105                 fatal("PAM: authentication thread exited uncleanly");
 106 }
 107
 108 static void
 109 pthread_exit(void *value __unused)
 110 {
 111         _exit(0);
 112 }
 113
 114 static int
 115 pthread_create(sp_pthread_t *thread, const void *attr __unused,
 116     void *(*thread_start)(void *), void *arg)
 117 {
 118         pid_t pid;
 119
 120         switch ((pid = fork())) {
 121         case -1:
 122                 error("fork(): %s", strerror(errno));
 123                 return (-1);
 124         case 0:
 125                 thread_start(arg);
 126                 _exit(1);
 127         default:
 128                 *thread = pid;
 129                 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
 130                 return (0);
 131         }
 132 }
 133
 134 static int
 135 pthread_cancel(sp_pthread_t thread)
 136 {
 137         signal(SIGCHLD, sshpam_oldsig);
 138         return (kill(thread, SIGTERM));
 139 }
 140
 141 static int
 142 pthread_join(sp_pthread_t thread, void **value __unused)
 143 {
 144         int status;
 145
 146         if (sshpam_thread_status != -1)
 147                 return (sshpam_thread_status);
 148         signal(SIGCHLD, sshpam_oldsig);
 149         waitpid(thread, &status, 0);
 150         return (status);
 151 }
 152 #endif
 153
 154
 155 static pam_handle_t *sshpam_handle = NULL;
 156 static int sshpam_err = 0;
 157 static int sshpam_authenticated = 0;
 158 static int sshpam_new_authtok_reqd = 0;
 159 static int sshpam_session_open = 0;
 160 static int sshpam_cred_established = 0;
 161 static int sshpam_account_status = -1;
 162 static char **sshpam_env = NULL;
 163
 164 /* Some PAM implementations don't implement this */
 165 #ifndef HAVE_PAM_GETENVLIST
 166 static char **
 167 pam_getenvlist(pam_handle_t *pamh)
 168 {
 169         /*
 170          * XXX - If necessary, we can still support envrionment passing
 171          * for platforms without pam_getenvlist by searching for known
 172          * env vars (e.g. KRB5CCNAME) from the PAM environment.
 173          */
 174          return NULL;
 175 }
 176 #endif
 177
 178 void
 179 pam_password_change_required(int reqd)
 180 {
 181         sshpam_new_authtok_reqd = reqd;
 182         if (reqd) {
 183                 no_port_forwarding_flag |= 2;
 184                 no_agent_forwarding_flag |= 2;
 185                 no_x11_forwarding_flag |= 2;
 186         } else {
 187                 no_port_forwarding_flag &= ~2;
 188                 no_agent_forwarding_flag &= ~2;
 189                 no_x11_forwarding_flag &= ~2;
 190
 191         }
 192 }
 193 /* Import regular and PAM environment from subprocess */
 194 static void
 195 import_environments(Buffer *b)
 196 {
 197         char *env;
 198         u_int i, num_env;
 199         int err;
 200
 201         /* Import variables set by do_pam_account */
 202         sshpam_account_status = buffer_get_int(b);
 203         pam_password_change_required(buffer_get_int(b));
 204
 205         /* Import environment from subprocess */
 206         num_env = buffer_get_int(b);
 207         sshpam_env = xmalloc((num_env + 1) * sizeof(*sshpam_env));
 208         debug3("PAM: num env strings %d", num_env);
 209         for(i = 0; i < num_env; i++)
 210                 sshpam_env[i] = buffer_get_string(b, NULL);
 211
 212         sshpam_env[num_env] = NULL;
 213
 214         /* Import PAM environment from subprocess */
 215         num_env = buffer_get_int(b);
 216         debug("PAM: num PAM env strings %d", num_env);
 217         for(i = 0; i < num_env; i++) {
 218                 env = buffer_get_string(b, NULL);
 219
 220 #ifdef HAVE_PAM_PUTENV
 221                 /* Errors are not fatal here */
 222                 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
 223                         error("PAM: pam_putenv: %s",
 224                             pam_strerror(sshpam_handle, sshpam_err));
 225                 }
 226 #endif
 227         }
 228 }
 229
 230 /*
 231  * Conversation function for authentication thread.
 232  */
 233 static int
 234 sshpam_thread_conv(int n, const struct pam_message **msg,
 235     struct pam_response **resp, void *data)
 236 {
 237         Buffer buffer;
 238         struct pam_ctxt *ctxt;
 239         struct pam_response *reply;
 240         int i;
 241
 242         *resp = NULL;
 243
 244         ctxt = data;
 245         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 246                 return (PAM_CONV_ERR);
 247
 248         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 249                 return (PAM_CONV_ERR);
 250         memset(reply, 0, n * sizeof(*reply));
 251
 252         buffer_init(&buffer);
 253         for (i = 0; i < n; ++i) {
 254                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 255                 case PAM_PROMPT_ECHO_OFF:
 256                         buffer_put_cstring(&buffer,
 257                             PAM_MSG_MEMBER(msg, i, msg));
 258                         if (ssh_msg_send(ctxt->pam_csock,
 259                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 260                                 goto fail;
 261                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 262                                 goto fail;
 263                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 264                                 goto fail;
 265                         reply[i].resp = buffer_get_string(&buffer, NULL);
 266                         break;
 267                 case PAM_PROMPT_ECHO_ON:
 268                         buffer_put_cstring(&buffer,
 269                             PAM_MSG_MEMBER(msg, i, msg));
 270                         if (ssh_msg_send(ctxt->pam_csock,
 271                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 272                                 goto fail;
 273                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 274                                 goto fail;
 275                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 276                                 goto fail;
 277                         reply[i].resp = buffer_get_string(&buffer, NULL);
 278                         break;
 279                 case PAM_ERROR_MSG:
 280                         buffer_put_cstring(&buffer,
 281                             PAM_MSG_MEMBER(msg, i, msg));
 282                         if (ssh_msg_send(ctxt->pam_csock,
 283                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 284                                 goto fail;
 285                         break;
 286                 case PAM_TEXT_INFO:
 287                         buffer_put_cstring(&buffer,
 288                             PAM_MSG_MEMBER(msg, i, msg));
 289                         if (ssh_msg_send(ctxt->pam_csock,
 290                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 291                                 goto fail;
 292                         break;
 293                 default:
 294                         goto fail;
 295                 }
 296                 buffer_clear(&buffer);
 297         }
 298         buffer_free(&buffer);
 299         *resp = reply;
 300         return (PAM_SUCCESS);
 301
 302  fail:
 303         for(i = 0; i < n; i++) {
 304                 if (reply[i].resp != NULL)
 305                         xfree(reply[i].resp);
 306         }
 307         xfree(reply);
 308         buffer_free(&buffer);
 309         return (PAM_CONV_ERR);
 310 }
 311
 312 /*
 313  * Authentication thread.
 314  */
 315 static void *
 316 sshpam_thread(void *ctxtp)
 317 {
 318         struct pam_ctxt *ctxt = ctxtp;
 319         Buffer buffer;
 320         struct pam_conv sshpam_conv;
 321 #ifndef USE_POSIX_THREADS
 322         extern char **environ;
 323         char **env_from_pam;
 324         u_int i;
 325         const char *pam_user;
 326
 327         pam_get_item(sshpam_handle, PAM_USER, (const void **)&pam_user);
 328         setproctitle("%s [pam]", pam_user);
 329         environ[0] = NULL;
 330 #endif
 331
 332         sshpam_conv.conv = sshpam_thread_conv;
 333         sshpam_conv.appdata_ptr = ctxt;
 334
 335         buffer_init(&buffer);
 336         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 337             (const void *)&sshpam_conv);
 338         if (sshpam_err != PAM_SUCCESS)
 339                 goto auth_fail;
 340         sshpam_err = pam_authenticate(sshpam_handle, 0);
 341         if (sshpam_err != PAM_SUCCESS)
 342                 goto auth_fail;
 343
 344         if (compat20) {
 345                 if (!do_pam_account())
 346                         goto auth_fail;
 347                 if (sshpam_new_authtok_reqd) {
 348                         sshpam_err = pam_chauthtok(sshpam_handle,
 349                             PAM_CHANGE_EXPIRED_AUTHTOK);
 350                         if (sshpam_err != PAM_SUCCESS)
 351                                 goto auth_fail;
 352                         pam_password_change_required(0);
 353                 }
 354         }
 355
 356         buffer_put_cstring(&buffer, "OK");
 357
 358 #ifndef USE_POSIX_THREADS
 359         /* Export variables set by do_pam_account */
 360         buffer_put_int(&buffer, sshpam_account_status);
 361         buffer_put_int(&buffer, sshpam_new_authtok_reqd);
 362
 363         /* Export any environment strings set in child */
 364         for(i = 0; environ[i] != NULL; i++)
 365                 ; /* Count */
 366         buffer_put_int(&buffer, i);
 367         for(i = 0; environ[i] != NULL; i++)
 368                 buffer_put_cstring(&buffer, environ[i]);
 369
 370         /* Export any environment strings set by PAM in child */
 371         env_from_pam = pam_getenvlist(sshpam_handle);
 372         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 373                 ; /* Count */
 374         buffer_put_int(&buffer, i);
 375         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 376                 buffer_put_cstring(&buffer, env_from_pam[i]);
 377 #endif /* USE_POSIX_THREADS */
 378
 379         /* XXX - can't do much about an error here */
 380         ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
 381         buffer_free(&buffer);
 382         pthread_exit(NULL);
 383
 384  auth_fail:
 385         buffer_put_cstring(&buffer,
 386             pam_strerror(sshpam_handle, sshpam_err));
 387         /* XXX - can't do much about an error here */
 388         ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
 389         buffer_free(&buffer);
 390         pthread_exit(NULL);
 391
 392         return (NULL); /* Avoid warning for non-pthread case */
 393 }
 394
 395 void
 396 sshpam_thread_cleanup(void)
 397 {
 398         struct pam_ctxt *ctxt = cleanup_ctxt;
 399
 400         if (ctxt != NULL && ctxt->pam_thread != 0) {
 401                 pthread_cancel(ctxt->pam_thread);
 402                 pthread_join(ctxt->pam_thread, NULL);
 403                 close(ctxt->pam_psock);
 404                 close(ctxt->pam_csock);
 405                 memset(ctxt, 0, sizeof(*ctxt));
 406                 cleanup_ctxt = NULL;
 407         }
 408 }
 409
 410 static int
 411 sshpam_null_conv(int n, const struct pam_message **msg,
 412     struct pam_response **resp, void *data)
 413 {
 414         return (PAM_CONV_ERR);
 415 }
 416
 417 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
 418
 419 void
 420 sshpam_cleanup(void)
 421 {
 422         debug("PAM: cleanup");
 423         if (sshpam_handle == NULL)
 424                 return;
 425         pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 426         if (sshpam_cred_established) {
 427                 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
 428                 sshpam_cred_established = 0;
 429         }
 430         if (sshpam_session_open) {
 431                 pam_close_session(sshpam_handle, PAM_SILENT);
 432                 sshpam_session_open = 0;
 433         }
 434         sshpam_authenticated = sshpam_new_authtok_reqd = 0;
 435         pam_end(sshpam_handle, sshpam_err);
 436         sshpam_handle = NULL;
 437 }
 438
 439 static int
 440 sshpam_init(const char *user)
 441 {
 442         extern u_int utmp_len;
 443         extern char *__progname;
 444         const char *pam_rhost, *pam_user;
 445
 446         if (sshpam_handle != NULL) {
 447                 /* We already have a PAM context; check if the user matches */
 448                 sshpam_err = pam_get_item(sshpam_handle,
 449                     PAM_USER, (const void **)&pam_user);
 450                 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
 451                         return (0);
 452                 pam_end(sshpam_handle, sshpam_err);
 453                 sshpam_handle = NULL;
 454         }
 455         debug("PAM: initializing for \"%s\"", user);
 456         sshpam_err =
 457             pam_start(SSHD_PAM_SERVICE, user, &null_conv, &sshpam_handle);
 458         if (sshpam_err != PAM_SUCCESS) {
 459                 pam_end(sshpam_handle, sshpam_err);
 460                 sshpam_handle = NULL;
 461                 return (-1);
 462         }
 463         pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
 464         debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
 465         sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
 466         if (sshpam_err != PAM_SUCCESS) {
 467                 pam_end(sshpam_handle, sshpam_err);
 468                 sshpam_handle = NULL;
 469                 return (-1);
 470         }
 471 #ifdef PAM_TTY_KLUDGE
 472         /*
 473          * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
 474          * sshd doesn't set the tty until too late in the auth process and
 475          * may not even set one (for tty-less connections)
 476          */
 477         debug("PAM: setting PAM_TTY to \"ssh\"");
 478         sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
 479         if (sshpam_err != PAM_SUCCESS) {
 480                 pam_end(sshpam_handle, sshpam_err);
 481                 sshpam_handle = NULL;
 482                 return (-1);
 483         }
 484 #endif
 485         return (0);
 486 }
 487
 488 static void *
 489 sshpam_init_ctx(Authctxt *authctxt)
 490 {
 491         struct pam_ctxt *ctxt;
 492         int socks[2];
 493
 494         /* Refuse to start if we don't have PAM enabled */
 495         if (!options.use_pam)
 496                 return NULL;
 497
 498         /* Initialize PAM */
 499         if (sshpam_init(authctxt->user) == -1) {
 500                 error("PAM: initialization failed");
 501                 return (NULL);
 502         }
 503
 504         ctxt = xmalloc(sizeof *ctxt);
 505         memset(ctxt, 0, sizeof(*ctxt));
 506
 507         /* Start the authentication thread */
 508         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
 509                 error("PAM: failed create sockets: %s", strerror(errno));
 510                 xfree(ctxt);
 511                 return (NULL);
 512         }
 513         ctxt->pam_psock = socks[0];
 514         ctxt->pam_csock = socks[1];
 515         if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
 516                 error("PAM: failed to start authentication thread: %s",
 517                     strerror(errno));
 518                 close(socks[0]);
 519                 close(socks[1]);
 520                 xfree(ctxt);
 521                 return (NULL);
 522         }
 523         cleanup_ctxt = ctxt;
 524         return (ctxt);
 525 }
 526
 527 static int
 528 sshpam_query(void *ctx, char **name, char **info,
 529     u_int *num, char ***prompts, u_int **echo_on)
 530 {
 531         Buffer buffer;
 532         struct pam_ctxt *ctxt = ctx;
 533         size_t plen;
 534         u_char type;
 535         char *msg;
 536         size_t len;
 537
 538         buffer_init(&buffer);
 539         *name = xstrdup("");
 540         *info = xstrdup("");
 541         *prompts = xmalloc(sizeof(char *));
 542         **prompts = NULL;
 543         plen = 0;
 544         *echo_on = xmalloc(sizeof(u_int));
 545         while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
 546                 type = buffer_get_char(&buffer);
 547                 msg = buffer_get_string(&buffer, NULL);
 548                 switch (type) {
 549                 case PAM_PROMPT_ECHO_ON:
 550                 case PAM_PROMPT_ECHO_OFF:
 551                         *num = 1;
 552                         len = plen + strlen(msg) + 1;
 553                         **prompts = xrealloc(**prompts, len);
 554                         plen += snprintf(**prompts + plen, len, "%s", msg);
 555                         **echo_on = (type == PAM_PROMPT_ECHO_ON);
 556                         xfree(msg);
 557                         return (0);
 558                 case PAM_ERROR_MSG:
 559                 case PAM_TEXT_INFO:
 560                         /* accumulate messages */
 561                         len = plen + strlen(msg) + 2;
 562                         **prompts = xrealloc(**prompts, len);
 563                         plen += snprintf(**prompts + plen, len, "%s\n", msg);
 564                         xfree(msg);
 565                         break;
 566                 case PAM_SUCCESS:
 567                 case PAM_AUTH_ERR:
 568                         if (**prompts != NULL) {
 569                                 /* drain any accumulated messages */
 570                                 debug("PAM: %s", **prompts);
 571                                 buffer_append(&loginmsg, **prompts,
 572                                     strlen(**prompts));
 573                                 xfree(**prompts);
 574                                 **prompts = NULL;
 575                         }
 576                         if (type == PAM_SUCCESS) {
 577                                 import_environments(&buffer);
 578                                 *num = 0;
 579                                 **echo_on = 0;
 580                                 ctxt->pam_done = 1;
 581                                 xfree(msg);
 582                                 return (0);
 583                         }
 584                         error("PAM: %s", msg);
 585                         /* FALLTHROUGH */
 586                 default:
 587                         *num = 0;
 588                         **echo_on = 0;
 589                         xfree(msg);
 590                         ctxt->pam_done = -1;
 591                         return (-1);
 592                 }
 593         }
 594         return (-1);
 595 }
 596
 597 /* XXX - see also comment in auth-chall.c:verify_response */
 598 static int
 599 sshpam_respond(void *ctx, u_int num, char **resp)
 600 {
 601         Buffer buffer;
 602         struct pam_ctxt *ctxt = ctx;
 603
 604         debug2("PAM: %s", __func__);
 605         switch (ctxt->pam_done) {
 606         case 1:
 607                 sshpam_authenticated = 1;
 608                 return (0);
 609         case 0:
 610                 break;
 611         default:
 612                 return (-1);
 613         }
 614         if (num != 1) {
 615                 error("PAM: expected one response, got %u", num);
 616                 return (-1);
 617         }
 618         buffer_init(&buffer);
 619         buffer_put_cstring(&buffer, *resp);
 620         if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
 621                 buffer_free(&buffer);
 622                 return (-1);
 623         }
 624         buffer_free(&buffer);
 625         return (1);
 626 }
 627
 628 static void
 629 sshpam_free_ctx(void *ctxtp)
 630 {
 631         struct pam_ctxt *ctxt = ctxtp;
 632
 633         sshpam_thread_cleanup();
 634         xfree(ctxt);
 635         /*
 636          * We don't call sshpam_cleanup() here because we may need the PAM
 637          * handle at a later stage, e.g. when setting up a session.  It's
 638          * still on the cleanup list, so pam_end() *will* be called before
 639          * the server process terminates.
 640          */
 641 }
 642
 643 KbdintDevice sshpam_device = {
 644         "pam",
 645         sshpam_init_ctx,
 646         sshpam_query,
 647         sshpam_respond,
 648         sshpam_free_ctx
 649 };
 650
 651 KbdintDevice mm_sshpam_device = {
 652         "pam",
 653         mm_sshpam_init_ctx,
 654         mm_sshpam_query,
 655         mm_sshpam_respond,
 656         mm_sshpam_free_ctx
 657 };
 658
 659 /*
 660  * This replaces auth-pam.c
 661  */
 662 void
 663 start_pam(const char *user)
 664 {
 665         if (!options.use_pam)
 666                 fatal("PAM: initialisation requested when UsePAM=no");
 667
 668         if (sshpam_init(user) == -1)
 669                 fatal("PAM: initialisation failed");
 670 }
 671
 672 void
 673 finish_pam(void)
 674 {
 675         sshpam_cleanup();
 676 }
 677
 678 u_int
 679 do_pam_account(void)
 680 {
 681         if (sshpam_account_status != -1)
 682                 return (sshpam_account_status);
 683
 684         sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
 685         debug3("%s: pam_acct_mgmt = %d", __func__, sshpam_err);
 686
 687         if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
 688                 sshpam_account_status = 0;
 689                 return (sshpam_account_status);
 690         }
 691
 692         if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
 693                 pam_password_change_required(1);
 694
 695         sshpam_account_status = 1;
 696         return (sshpam_account_status);
 697 }
 698
 699 void
 700 do_pam_set_tty(const char *tty)
 701 {
 702         if (tty != NULL) {
 703                 debug("PAM: setting PAM_TTY to \"%s\"", tty);
 704                 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
 705                 if (sshpam_err != PAM_SUCCESS)
 706                         fatal("PAM: failed to set PAM_TTY: %s",
 707                             pam_strerror(sshpam_handle, sshpam_err));
 708         }
 709 }
 710
 711 void
 712 do_pam_setcred(int init)
 713 {
 714         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 715             (const void *)&null_conv);
 716         if (sshpam_err != PAM_SUCCESS)
 717                 fatal("PAM: failed to set PAM_CONV: %s",
 718                     pam_strerror(sshpam_handle, sshpam_err));
 719         if (init) {
 720                 debug("PAM: establishing credentials");
 721                 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
 722         } else {
 723                 debug("PAM: reinitializing credentials");
 724                 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
 725         }
 726         if (sshpam_err == PAM_SUCCESS) {
 727                 sshpam_cred_established = 1;
 728                 return;
 729         }
 730         if (sshpam_authenticated)
 731                 fatal("PAM: pam_setcred(): %s",
 732                     pam_strerror(sshpam_handle, sshpam_err));
 733         else
 734                 debug("PAM: pam_setcred(): %s",
 735                     pam_strerror(sshpam_handle, sshpam_err));
 736 }
 737
 738 int
 739 is_pam_password_change_required(void)
 740 {
 741         return (sshpam_new_authtok_reqd);
 742 }
 743
 744 static int
 745 pam_tty_conv(int n, const struct pam_message **msg,
 746     struct pam_response **resp, void *data)
 747 {
 748         char input[PAM_MAX_MSG_SIZE];
 749         struct pam_response *reply;
 750         int i;
 751
 752         *resp = NULL;
 753
 754         if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
 755                 return (PAM_CONV_ERR);
 756
 757         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 758                 return (PAM_CONV_ERR);
 759         memset(reply, 0, n * sizeof(*reply));
 760
 761         for (i = 0; i < n; ++i) {
 762                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 763                 case PAM_PROMPT_ECHO_OFF:
 764                         reply[i].resp =
 765                             read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
 766                             RP_ALLOW_STDIN);
 767                         reply[i].resp_retcode = PAM_SUCCESS;
 768                         break;
 769                 case PAM_PROMPT_ECHO_ON:
 770                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 771                         fgets(input, sizeof input, stdin);
 772                         reply[i].resp = xstrdup(input);
 773                         reply[i].resp_retcode = PAM_SUCCESS;
 774                         break;
 775                 case PAM_ERROR_MSG:
 776                 case PAM_TEXT_INFO:
 777                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 778                         reply[i].resp_retcode = PAM_SUCCESS;
 779                         break;
 780                 default:
 781                         goto fail;
 782                 }
 783         }
 784         *resp = reply;
 785         return (PAM_SUCCESS);
 786
 787  fail:
 788         for(i = 0; i < n; i++) {
 789                 if (reply[i].resp != NULL)
 790                         xfree(reply[i].resp);
 791         }
 792         xfree(reply);
 793         return (PAM_CONV_ERR);
 794 }
 795
 796 static struct pam_conv tty_conv = { pam_tty_conv, NULL };
 797
 798 /*
 799  * XXX this should be done in the authentication phase, but ssh1 doesn't
 800  * support that
 801  */
 802 void
 803 do_pam_chauthtok(void)
 804 {
 805         if (use_privsep)
 806                 fatal("Password expired (unable to change with privsep)");
 807         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 808             (const void *)&tty_conv);
 809         if (sshpam_err != PAM_SUCCESS)
 810                 fatal("PAM: failed to set PAM_CONV: %s",
 811                     pam_strerror(sshpam_handle, sshpam_err));
 812         debug("PAM: changing password");
 813         sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
 814         if (sshpam_err != PAM_SUCCESS)
 815                 fatal("PAM: pam_chauthtok(): %s",
 816                     pam_strerror(sshpam_handle, sshpam_err));
 817 }
 818
 819 void
 820 do_pam_session(void)
 821 {
 822         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 823             (const void *)&tty_conv);
 824         if (sshpam_err != PAM_SUCCESS)
 825                 fatal("PAM: failed to set PAM_CONV: %s",
 826                     pam_strerror(sshpam_handle, sshpam_err));
 827         sshpam_err = pam_open_session(sshpam_handle, 0);
 828         if (sshpam_err != PAM_SUCCESS)
 829                 fatal("PAM: pam_open_session(): %s",
 830                     pam_strerror(sshpam_handle, sshpam_err));
 831         sshpam_session_open = 1;
 832 }
 833
 834 /*
 835  * Set a PAM environment string. We need to do this so that the session
 836  * modules can handle things like Kerberos/GSI credentials that appear
 837  * during the ssh authentication process.
 838  */
 839 int
 840 do_pam_putenv(char *name, char *value)
 841 {
 842         int ret = 1;
 843 #ifdef HAVE_PAM_PUTENV
 844         char *compound;
 845         size_t len;
 846
 847         len = strlen(name) + strlen(value) + 2;
 848         compound = xmalloc(len);
 849
 850         snprintf(compound, len, "%s=%s", name, value);
 851         ret = pam_putenv(sshpam_handle, compound);
 852         xfree(compound);
 853 #endif
 854
 855         return (ret);
 856 }
 857
 858 void
 859 print_pam_messages(void)
 860 {
 861         /* XXX */
 862 }
 863
 864 char **
 865 fetch_pam_child_environment(void)
 866 {
 867         return sshpam_env;
 868 }
 869
 870 char **
 871 fetch_pam_environment(void)
 872 {
 873         return (pam_getenvlist(sshpam_handle));
 874 }
 875
 876 void
 877 free_pam_environment(char **env)
 878 {
 879         char **envp;
 880
 881         if (env == NULL)
 882                 return;
 883
 884         for (envp = env; *envp; envp++)
 885                 xfree(*envp);
 886         xfree(env);
 887 }
 888
 889 #endif /* USE_PAM */