secure/usr.sbin/sshd/auth2-pam-freebsd.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  * $FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.1.2.6 2003/04/07 09:56:46 des Exp $
  32  * $DragonFly: src/secure/usr.sbin/sshd/Attic/auth2-pam-freebsd.c,v 1.3 2005/07/11 22:49:46 corecode Exp $
  33  */
  34
  35 #include "includes.h"
  36
  37 #ifdef USE_PAM
  38 #include <security/pam_appl.h>
  39
  40 #include "auth.h"
  41 #include "auth-pam.h"
  42 #include "buffer.h"
  43 #include "bufaux.h"
  44 #include "canohost.h"
  45 #include "log.h"
  46 #include "monitor_wrap.h"
  47 #include "msg.h"
  48 #include "packet.h"
  49 #include "misc.h"
  50 #include "servconf.h"
  51 #include "ssh2.h"
  52 #include "xmalloc.h"
  53
  54 #ifdef USE_POSIX_THREADS
  55 #include <pthread.h>
  56 #else
  57 typedef pid_t pthread_t;
  58 #endif
  59
  60 struct pam_ctxt {
  61         pthread_t        pam_thread;
  62         int              pam_psock;
  63         int              pam_csock;
  64         int              pam_done;
  65 };
  66
  67 static void sshpam_free_ctx(void *);
  68 static struct pam_ctxt *cleanup_ctxt;
  69 static Authctxt *sshpam_authctxt = NULL;
  70 static const char *sshpam_password = NULL;
  71
  72
  73 #ifndef USE_POSIX_THREADS
  74 /*
  75  * Simulate threads with processes.
  76  */
  77
  78 static int sshpam_thread_status = -1;
  79 static mysig_t sshpam_oldsig;
  80
  81 static void
  82 sshpam_sigchld_handler(int sig)
  83 {
  84         if (cleanup_ctxt == NULL)
  85                 return; /* handler called after PAM cleanup, shouldn't happen */
  86         if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0) == -1)
  87                 return; /* couldn't wait for process */
  88         if (WIFSIGNALED(sshpam_thread_status) &&
  89             WTERMSIG(sshpam_thread_status) == SIGTERM)
  90                 return; /* terminated by pthread_cancel */
  91         if (!WIFEXITED(sshpam_thread_status))
  92                 fatal("PAM: authentication thread exited unexpectedly");
  93         if (WEXITSTATUS(sshpam_thread_status) != 0)
  94                 fatal("PAM: authentication thread exited uncleanly");
  95 }
  96
  97
  98 static void
  99 pthread_exit(void *value __unused)
 100 {
 101         _exit(0);
 102 }
 103
 104 static int
 105 pthread_create(pthread_t *thread, const void *attr __unused,
 106     void *(*thread_start)(void *), void *arg)
 107 {
 108         pid_t pid;
 109
 110         switch ((pid = fork())) {
 111         case -1:
 112                 error("fork(): %s", strerror(errno));
 113                 return (-1);
 114         case 0:
 115                 thread_start(arg);
 116                 _exit(1);
 117         default:
 118                 *thread = pid;
 119                 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
 120                 return (0);
 121         }
 122 }
 123
 124 static int
 125 pthread_cancel(pthread_t thread)
 126 {
 127         signal(SIGCHLD, sshpam_oldsig);
 128         return (kill(thread, SIGTERM));
 129 }
 130
 131 static int
 132 pthread_join(pthread_t thread, void **value __unused)
 133 {
 134         int status;
 135
 136         if (sshpam_thread_status != -1)
 137                 return (sshpam_thread_status);
 138         signal(SIGCHLD, sshpam_oldsig);
 139         waitpid(thread, &status, 0);
 140         return (status);
 141 }
 142 #endif
 143
 144
 145 extern ServerOptions options;
 146 extern Buffer loginmsg;
 147 extern int compat20;
 148 extern u_int utmp_len;
 149
 150 static pam_handle_t *sshpam_handle;
 151 static int sshpam_err;
 152 static int sshpam_authenticated;
 153 static int sshpam_new_authtok_reqd;
 154 static int sshpam_session_open;
 155 static int sshpam_cred_established;
 156
 157 /*
 158  * Conversation function for authentication thread.
 159  */
 160 static int
 161 sshpam_thread_conv(int n,
 162          const struct pam_message **msg,
 163          struct pam_response **resp,
 164          void *data)
 165 {
 166         Buffer buffer;
 167         struct pam_ctxt *ctxt;
 168         int i;
 169
 170         ctxt = data;
 171         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 172                 return (PAM_CONV_ERR);
 173         *resp = xmalloc(n * sizeof **resp);
 174         buffer_init(&buffer);
 175         for (i = 0; i < n; ++i) {
 176                 resp[i]->resp_retcode = 0;
 177                 resp[i]->resp = NULL;
 178                 switch (msg[i]->msg_style) {
 179                 case PAM_PROMPT_ECHO_OFF:
 180                         buffer_put_cstring(&buffer, msg[i]->msg);
 181                         ssh_msg_send(ctxt->pam_csock, msg[i]->msg_style, &buffer);
 182                         ssh_msg_recv(ctxt->pam_csock, &buffer);
 183                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 184                                 goto fail;
 185                         resp[i]->resp = buffer_get_string(&buffer, NULL);
 186                         break;
 187                 case PAM_PROMPT_ECHO_ON:
 188                         buffer_put_cstring(&buffer, msg[i]->msg);
 189                         ssh_msg_send(ctxt->pam_csock, msg[i]->msg_style, &buffer);
 190                         ssh_msg_recv(ctxt->pam_csock, &buffer);
 191                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 192                                 goto fail;
 193                         resp[i]->resp = buffer_get_string(&buffer, NULL);
 194                         break;
 195                 case PAM_ERROR_MSG:
 196                         buffer_put_cstring(&buffer, msg[i]->msg);
 197                         ssh_msg_send(ctxt->pam_csock, msg[i]->msg_style, &buffer);
 198                         break;
 199                 case PAM_TEXT_INFO:
 200                         buffer_put_cstring(&buffer, msg[i]->msg);
 201                         ssh_msg_send(ctxt->pam_csock, msg[i]->msg_style, &buffer);
 202                         break;
 203                 default:
 204                         goto fail;
 205                 }
 206                 buffer_clear(&buffer);
 207         }
 208         buffer_free(&buffer);
 209         return (PAM_SUCCESS);
 210  fail:
 211         while (i)
 212                 xfree(resp[--i]);
 213         xfree(*resp);
 214         *resp = NULL;
 215         buffer_free(&buffer);
 216         return (PAM_CONV_ERR);
 217 }
 218
 219 /*
 220  * Authentication thread.
 221  */
 222 static void *
 223 sshpam_thread(void *ctxtp)
 224 {
 225         struct pam_ctxt *ctxt = ctxtp;
 226         Buffer buffer;
 227         struct pam_conv pam_conv = { sshpam_thread_conv, ctxt };
 228
 229 #ifndef USE_POSIX_THREADS
 230         {
 231                 const char *pam_user;
 232
 233                 pam_get_item(sshpam_handle, PAM_USER, (const void **)&pam_user);
 234                 setproctitle("%s [pam]", pam_user);
 235         }
 236 #endif
 237         buffer_init(&buffer);
 238         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, (const void *)&pam_conv);
 239         if (sshpam_err != PAM_SUCCESS)
 240                 goto auth_fail;
 241         sshpam_err = pam_authenticate(sshpam_handle, 0);
 242         if (sshpam_err != PAM_SUCCESS)
 243                 goto auth_fail;
 244         sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
 245         if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD)
 246                 goto auth_fail;
 247         buffer_put_cstring(&buffer, "OK");
 248         ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
 249         buffer_free(&buffer);
 250         pthread_exit(NULL);
 251  auth_fail:
 252         buffer_put_cstring(&buffer,
 253             pam_strerror(sshpam_handle, sshpam_err));
 254         ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
 255         buffer_free(&buffer);
 256         pthread_exit(NULL);
 257 }
 258
 259 void
 260 sshpam_thread_cleanup(void)
 261 {
 262         struct pam_ctxt *ctxt = cleanup_ctxt;
 263
 264         if (ctxt != NULL && ctxt->pam_thread != 0) {
 265                 pthread_cancel(ctxt->pam_thread);
 266                 pthread_join(ctxt->pam_thread, NULL);
 267                 close(ctxt->pam_psock);
 268                 close(ctxt->pam_csock);
 269                 memset(ctxt, 0, sizeof(*ctxt));
 270                 cleanup_ctxt = NULL;
 271         }
 272 }
 273
 274 static int
 275 sshpam_null_conv(int n,
 276          const struct pam_message **msg,
 277          struct pam_response **resp,
 278          void *data)
 279 {
 280
 281         return (PAM_CONV_ERR);
 282 }
 283
 284 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
 285
 286 void
 287 sshpam_cleanup(void)
 288 {
 289         debug("PAM: cleanup");
 290         pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 291         if (sshpam_cred_established) {
 292                 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
 293                 sshpam_cred_established = 0;
 294         }
 295         if (sshpam_session_open) {
 296                 pam_close_session(sshpam_handle, PAM_SILENT);
 297                 sshpam_session_open = 0;
 298         }
 299         sshpam_authenticated = sshpam_new_authtok_reqd = 0;
 300         pam_end(sshpam_handle, sshpam_err);
 301         sshpam_handle = NULL;
 302 }
 303
 304 static int
 305 sshpam_init(Authctxt *authctxt)
 306 {
 307         extern u_int utmp_len;
 308         const char *pam_rhost, *pam_user, *user = authctxt->user;
 309
 310         if (sshpam_handle != NULL) {
 311                 /* We already have a PAM context; check if the user matches */
 312                 sshpam_err = pam_get_item(sshpam_handle,
 313                     PAM_USER, (const void **)&pam_user);
 314                 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
 315                         return (0);
 316                 pam_end(sshpam_handle, sshpam_err);
 317                 sshpam_handle = NULL;
 318         }
 319         debug("PAM: initializing for \"%s\"", user);
 320         sshpam_err = pam_start("sshd", user, &null_conv, &sshpam_handle);
 321         if (sshpam_err != PAM_SUCCESS)
 322                 return (-1);
 323         pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
 324         debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
 325         sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
 326         if (sshpam_err != PAM_SUCCESS) {
 327                 pam_end(sshpam_handle, sshpam_err);
 328                 sshpam_handle = NULL;
 329                 return (-1);
 330         }
 331         return (0);
 332 }
 333
 334 static void *
 335 sshpam_init_ctx(Authctxt *authctxt)
 336 {
 337         struct pam_ctxt *ctxt;
 338         int socks[2];
 339
 340         /* Initialize PAM */
 341         if (sshpam_init(authctxt) == -1) {
 342                 error("PAM: initialization failed");
 343                 return (NULL);
 344         }
 345
 346         ctxt = xmalloc(sizeof *ctxt);
 347         ctxt->pam_done = 0;
 348
 349         /* Start the authentication thread */
 350         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
 351                 error("PAM: failed create sockets: %s", strerror(errno));
 352                 xfree(ctxt);
 353                 return (NULL);
 354         }
 355         ctxt->pam_psock = socks[0];
 356         ctxt->pam_csock = socks[1];
 357         if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
 358                 error("PAM: failed to start authentication thread: %s",
 359                     strerror(errno));
 360                 close(socks[0]);
 361                 close(socks[1]);
 362                 xfree(ctxt);
 363                 return (NULL);
 364         }
 365         cleanup_ctxt = ctxt;
 366         return (ctxt);
 367 }
 368
 369 static int
 370 sshpam_query(void *ctx, char **name, char **info,
 371     u_int *num, char ***prompts, u_int **echo_on)
 372 {
 373         Buffer buffer;
 374         struct pam_ctxt *ctxt = ctx;
 375         size_t plen;
 376         u_char type;
 377         char *msg;
 378
 379         buffer_init(&buffer);
 380         *name = xstrdup("");
 381         *info = xstrdup("");
 382         *prompts = xmalloc(sizeof(char *));
 383         **prompts = NULL;
 384         plen = 0;
 385         *echo_on = xmalloc(sizeof(u_int));
 386         while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
 387                 type = buffer_get_char(&buffer);
 388                 msg = buffer_get_string(&buffer, NULL);
 389                 switch (type) {
 390                 case PAM_PROMPT_ECHO_ON:
 391                 case PAM_PROMPT_ECHO_OFF:
 392                         *num = 1;
 393                         **prompts = xrealloc(**prompts, plen + strlen(msg) + 1);
 394                         plen += sprintf(**prompts + plen, "%s", msg);
 395                         **echo_on = (type == PAM_PROMPT_ECHO_ON);
 396                         xfree(msg);
 397                         return (0);
 398                 case PAM_ERROR_MSG:
 399                 case PAM_TEXT_INFO:
 400                         /* accumulate messages */
 401                         **prompts = xrealloc(**prompts, plen + strlen(msg) + 1);
 402                         plen += sprintf(**prompts + plen, "%s", msg);
 403                         xfree(msg);
 404                         break;
 405                 case PAM_NEW_AUTHTOK_REQD:
 406                         sshpam_new_authtok_reqd = 1;
 407                         /* FALLTHROUGH */
 408                 case PAM_SUCCESS:
 409                 case PAM_AUTH_ERR:
 410                         if (**prompts != NULL) {
 411                                 /* drain any accumulated messages */
 412 #if 0 /* not compatible with privsep */
 413                                 packet_start(SSH2_MSG_USERAUTH_BANNER);
 414                                 packet_put_cstring(**prompts);
 415                                 packet_put_cstring("");
 416                                 packet_send();
 417                                 packet_write_wait();
 418 #endif
 419                                 xfree(**prompts);
 420                                 **prompts = NULL;
 421                         }
 422                         if (type == PAM_SUCCESS) {
 423                                 *num = 0;
 424                                 **echo_on = 0;
 425                                 ctxt->pam_done = 1;
 426                                 xfree(msg);
 427                                 return (0);
 428                         }
 429                         error("PAM: %s", msg);
 430                 default:
 431                         *num = 0;
 432                         **echo_on = 0;
 433                         xfree(msg);
 434                         ctxt->pam_done = -1;
 435                         return (-1);
 436                 }
 437         }
 438         return (-1);
 439 }
 440
 441 static int
 442 sshpam_respond(void *ctx, u_int num, char **resp)
 443 {
 444         Buffer buffer;
 445         struct pam_ctxt *ctxt = ctx;
 446         char *msg;
 447
 448         debug2("PAM: %s", __func__);
 449         switch (ctxt->pam_done) {
 450         case 1:
 451                 sshpam_authenticated = 1;
 452                 return (0);
 453         case 0:
 454                 break;
 455         default:
 456                 return (-1);
 457         }
 458         if (num != 1) {
 459                 error("PAM: expected one response, got %u", num);
 460                 return (-1);
 461         }
 462         buffer_init(&buffer);
 463         buffer_put_cstring(&buffer, *resp);
 464         ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer);
 465         buffer_free(&buffer);
 466         return (1);
 467 }
 468
 469 static void
 470 sshpam_free_ctx(void *ctxtp)
 471 {
 472         struct pam_ctxt *ctxt = ctxtp;
 473
 474         sshpam_thread_cleanup();
 475         xfree(ctxt);
 476         /*
 477          * We don't call pam_cleanup() here because we may need the PAM
 478          * handle at a later stage, e.g. when setting up a session.  It's
 479          * still on the cleanup list, so pam_end() *will* be called before
 480          * the server process terminates.
 481          */
 482 }
 483
 484 KbdintDevice sshpam_device = {
 485         "pam",
 486         sshpam_init_ctx,
 487         sshpam_query,
 488         sshpam_respond,
 489         sshpam_free_ctx
 490 };
 491
 492 KbdintDevice mm_sshpam_device = {
 493         "pam",
 494         mm_sshpam_init_ctx,
 495         mm_sshpam_query,
 496         mm_sshpam_respond,
 497         mm_sshpam_free_ctx
 498 };
 499
 500 /*
 501  * This replaces auth-pam.c
 502  */
 503 void
 504 start_pam(Authctxt *authctxt)
 505 {
 506         if (!options.use_pam)
 507                 fatal("PAM: initialisation requested when UsePAM=no");
 508
 509         if (sshpam_init(authctxt) == -1)
 510                 fatal("PAM: initialisation failed");
 511 }
 512
 513 void
 514 finish_pam(void)
 515 {
 516         sshpam_cleanup();
 517 }
 518
 519 u_int
 520 do_pam_account(void)
 521 {
 522         /* XXX */
 523         return (1);
 524 }
 525
 526 void
 527 do_pam_set_tty(const char *tty)
 528 {
 529         if (tty != NULL) {
 530                 debug("PAM: setting PAM_TTY to \"%s\"", tty);
 531                 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
 532                 if (sshpam_err != PAM_SUCCESS)
 533                         fatal("PAM: failed to set PAM_TTY: %s",
 534                             pam_strerror(sshpam_handle, sshpam_err));
 535         }
 536 }
 537
 538 void
 539 do_pam_session(void)
 540 {
 541         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 542         if (sshpam_err != PAM_SUCCESS)
 543                 fatal("PAM: failed to set PAM_CONV: %s",
 544                     pam_strerror(sshpam_handle, sshpam_err));
 545         sshpam_err = pam_open_session(sshpam_handle, 0);
 546         if (sshpam_err != PAM_SUCCESS)
 547                 fatal("PAM: pam_open_session(): %s",
 548                     pam_strerror(sshpam_handle, sshpam_err));
 549         sshpam_session_open = 1;
 550 }
 551
 552 int
 553 is_pam_session_open(void)
 554 {
 555         return sshpam_session_open;
 556 }
 557
 558 void
 559 do_pam_setcred(int init)
 560 {
 561         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 562         if (sshpam_err != PAM_SUCCESS)
 563                 fatal("PAM: failed to set PAM_CONV: %s",
 564                     pam_strerror(sshpam_handle, sshpam_err));
 565         if (init) {
 566                 debug("PAM: establishing credentials");
 567                 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
 568         } else {
 569                 debug("PAM: reinitializing credentials");
 570                 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
 571         }
 572         if (sshpam_err == PAM_SUCCESS) {
 573                 sshpam_cred_established = 1;
 574                 return;
 575         }
 576         if (sshpam_authenticated)
 577                 fatal("PAM: pam_setcred(): %s",
 578                     pam_strerror(sshpam_handle, sshpam_err));
 579         else
 580                 debug("PAM: pam_setcred(): %s",
 581                     pam_strerror(sshpam_handle, sshpam_err));
 582 }
 583
 584 int
 585 is_pam_password_change_required(void)
 586 {
 587         return (sshpam_new_authtok_reqd);
 588 }
 589
 590 static int
 591 sshpam_chauthtok_conv(int n,
 592          const struct pam_message **msg,
 593          struct pam_response **resp,
 594          void *data)
 595 {
 596         char input[PAM_MAX_MSG_SIZE];
 597         int i;
 598
 599         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 600                 return (PAM_CONV_ERR);
 601         *resp = xmalloc(n * sizeof **resp);
 602         for (i = 0; i < n; ++i) {
 603                 switch (msg[i]->msg_style) {
 604                 case PAM_PROMPT_ECHO_OFF:
 605                         resp[i]->resp =
 606                             read_passphrase(msg[i]->msg, RP_ALLOW_STDIN);
 607                         resp[i]->resp_retcode = PAM_SUCCESS;
 608                         break;
 609                 case PAM_PROMPT_ECHO_ON:
 610                         fputs(msg[i]->msg, stderr);
 611                         fgets(input, sizeof input, stdin);
 612                         resp[i]->resp = xstrdup(input);
 613                         resp[i]->resp_retcode = PAM_SUCCESS;
 614                         break;
 615                 case PAM_ERROR_MSG:
 616                 case PAM_TEXT_INFO:
 617                         fputs(msg[i]->msg, stderr);
 618                         resp[i]->resp_retcode = PAM_SUCCESS;
 619                         break;
 620                 default:
 621                         goto fail;
 622                 }
 623         }
 624         return (PAM_SUCCESS);
 625  fail:
 626         while (i)
 627                 xfree(resp[--i]);
 628         xfree(*resp);
 629         *resp = NULL;
 630         return (PAM_CONV_ERR);
 631 }
 632
 633 /*
 634  * XXX this should be done in the authentication phase, but ssh1 doesn't
 635  * support that
 636  */
 637 void
 638 do_pam_chauthtok(void)
 639 {
 640         struct pam_conv pam_conv = { sshpam_chauthtok_conv, NULL };
 641
 642         if (use_privsep)
 643                 fatal("PAM: chauthtok not supprted with privsep");
 644         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, (const void *)&pam_conv);
 645         if (sshpam_err != PAM_SUCCESS)
 646                 fatal("PAM: failed to set PAM_CONV: %s",
 647                     pam_strerror(sshpam_handle, sshpam_err));
 648         debug("PAM: changing password");
 649         sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
 650         if (sshpam_err != PAM_SUCCESS)
 651                 fatal("PAM: pam_chauthtok(): %s",
 652                     pam_strerror(sshpam_handle, sshpam_err));
 653 }
 654
 655 void
 656 print_pam_messages(void)
 657 {
 658         /* XXX */
 659 }
 660
 661 char **
 662 fetch_pam_child_environment(void)
 663 {
 664         /* XXX */
 665         return (NULL);
 666 }
 667
 668 char **
 669 fetch_pam_environment(void)
 670 {
 671 #ifdef HAVE_PAM_GETENVLIST
 672         debug("PAM: retrieving environment");
 673         return (pam_getenvlist(sshpam_handle));
 674 #else
 675         return (NULL);
 676 #endif
 677 }
 678
 679 void
 680 free_pam_environment(char **env)
 681 {
 682         char **envp;
 683
 684         if (env == NULL)
 685                 return;
 686
 687         for (envp = env; *envp; envp++)
 688                 xfree(*envp);
 689         xfree(env);
 690 }
 691
 692 /*
 693  * "Blind" conversation function for password authentication.  Assumes that
 694  * echo-off prompts are for the password and stores messages for later
 695  * display.
 696  */
 697 static int
 698 sshpam_passwd_conv(int n, const struct pam_message **msg,
 699     struct pam_response **resp, void *data)
 700 {
 701         struct pam_response *reply;
 702         int i;
 703         size_t len;
 704
 705         debug3("PAM: %s called with %d messages", __func__, n);
 706
 707         *resp = NULL;
 708
 709         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 710                 return (PAM_CONV_ERR);
 711
 712         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 713                 return (PAM_CONV_ERR);
 714         memset(reply, 0, n * sizeof(*reply));
 715
 716         for (i = 0; i < n; ++i) {
 717                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 718                 case PAM_PROMPT_ECHO_OFF:
 719                         if (sshpam_password == NULL)
 720                                 goto fail;
 721                         if ((reply[i].resp = strdup(sshpam_password)) == NULL)
 722                                 goto fail;
 723                         reply[i].resp_retcode = PAM_SUCCESS;
 724                         break;
 725                 case PAM_ERROR_MSG:
 726                 case PAM_TEXT_INFO:
 727                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
 728                         if (len > 0) {
 729                                 buffer_append(&loginmsg,
 730                                     PAM_MSG_MEMBER(msg, i, msg), len);
 731                                 buffer_append(&loginmsg, "\n", 1);
 732                         }
 733                         if ((reply[i].resp = strdup("")) == NULL)
 734                                 goto fail;
 735                         reply[i].resp_retcode = PAM_SUCCESS;
 736                         break;
 737                 default:
 738                         goto fail;
 739                 }
 740         }
 741         *resp = reply;
 742         return (PAM_SUCCESS);
 743
 744  fail:
 745         for(i = 0; i < n; i++) {
 746                 if (reply[i].resp != NULL)
 747                         xfree(reply[i].resp);
 748         }
 749         xfree(reply);
 750         return (PAM_CONV_ERR);
 751 }
 752
 753 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
 754
 755 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
 756 {
 757         int flags = (options.permit_empty_passwd == 0 ?
 758             PAM_DISALLOW_NULL_AUTHTOK : 0);
 759         static char badpw[] = "\b\n\r\177INCORRECT";
 760
 761         if (!options.use_pam || sshpam_handle == NULL)
 762                 fatal("PAM: %s called when PAM disabled or failed to "
 763                     "initialise.", __func__);
 764
 765         sshpam_password = password;
 766         sshpam_authctxt = authctxt;
 767
 768         /*
 769          * If the user logging in is invalid, or is root but is not permitted
 770          * by PermitRootLogin, use an invalid password to prevent leaking
 771          * information via timing (eg if the PAM config has a delay on fail).
 772          */
 773         if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
 774              options.permit_root_login != PERMIT_YES))
 775                 sshpam_password = badpw;
 776
 777         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 778             (const void *)&passwd_conv);
 779         if (sshpam_err != PAM_SUCCESS)
 780                 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
 781                     pam_strerror(sshpam_handle, sshpam_err));
 782
 783         sshpam_err = pam_authenticate(sshpam_handle, flags);
 784         sshpam_password = NULL;
 785         if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
 786                 debug("PAM: password authentication accepted for %.100s",
 787                     authctxt->user);
 788                return 1;
 789         } else {
 790                 debug("PAM: password authentication failed for %.100s: %s",
 791                     authctxt->valid ? authctxt->user : "an illegal user",
 792                     pam_strerror(sshpam_handle, sshpam_err));
 793                 return 0;
 794         }
 795 }
 796
 797 #endif /* USE_PAM */