auth-pam.c

   1 /*-
   2  * Copyright (c) 2002 Networks Associates Technology, Inc.
   3  * All rights reserved.
   4  *
   5  * This software was developed for the FreeBSD Project by ThinkSec AS and
   6  * NAI Labs, the Security Research Division of Network Associates, Inc.
   7  * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
   8  * DARPA CHATS research program.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31 /*
  32  * Copyright (c) 2003,2004 Damien Miller <djm@mindrot.org>
  33  * Copyright (c) 2003,2004 Darren Tucker <dtucker@zip.com.au>
  34  *
  35  * Permission to use, copy, modify, and distribute this software for any
  36  * purpose with or without fee is hereby granted, provided that the above
  37  * copyright notice and this permission notice appear in all copies.
  38  *
  39  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  40  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  41  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  42  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  43  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  44  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  45  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  46  */
  47
  48 /* Based on $FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des Exp $ */
  49 #include "includes.h"
  50 RCSID("$Id$");
  51
  52 #ifdef USE_PAM
  53 #if defined(HAVE_SECURITY_PAM_APPL_H)
  54 #include <security/pam_appl.h>
  55 #elif defined (HAVE_PAM_PAM_APPL_H)
  56 #include <pam/pam_appl.h>
  57 #endif
  58
  59 #include "auth.h"
  60 #include "auth-pam.h"
  61 #include "buffer.h"
  62 #include "bufaux.h"
  63 #include "canohost.h"
  64 #include "log.h"
  65 #include "monitor_wrap.h"
  66 #include "msg.h"
  67 #include "packet.h"
  68 #include "misc.h"
  69 #include "servconf.h"
  70 #include "ssh2.h"
  71 #include "xmalloc.h"
  72 #include "auth-options.h"
  73
  74 extern ServerOptions options;
  75 extern Buffer loginmsg;
  76 extern int compat20;
  77 extern u_int utmp_len;
  78
  79 #ifdef USE_POSIX_THREADS
  80 #include <pthread.h>
  81 /*
  82  * Avoid namespace clash when *not* using pthreads for systems *with*
  83  * pthreads, which unconditionally define pthread_t via sys/types.h
  84  * (e.g. Linux)
  85  */
  86 typedef pthread_t sp_pthread_t;
  87 #else
  88 typedef pid_t sp_pthread_t;
  89 #endif
  90
  91 struct pam_ctxt {
  92         sp_pthread_t     pam_thread;
  93         int              pam_psock;
  94         int              pam_csock;
  95         int              pam_done;
  96 };
  97
  98 static void sshpam_free_ctx(void *);
  99 static struct pam_ctxt *cleanup_ctxt;
 100
 101 #ifndef USE_POSIX_THREADS
 102 /*
 103  * Simulate threads with processes.
 104  */
 105
 106 static int sshpam_thread_status = -1;
 107 static mysig_t sshpam_oldsig;
 108
 109 static void
 110 sshpam_sigchld_handler(int sig)
 111 {
 112         signal(SIGCHLD, SIG_DFL);
 113         if (cleanup_ctxt == NULL)
 114                 return; /* handler called after PAM cleanup, shouldn't happen */
 115         if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
 116              <= 0) {
 117                 /* PAM thread has not exitted, privsep slave must have */
 118                 kill(cleanup_ctxt->pam_thread, SIGTERM);
 119                 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0)
 120                     <= 0)
 121                         return; /* could not wait */
 122         }
 123         if (WIFSIGNALED(sshpam_thread_status) &&
 124             WTERMSIG(sshpam_thread_status) == SIGTERM)
 125                 return; /* terminated by pthread_cancel */
 126         if (!WIFEXITED(sshpam_thread_status))
 127                 fatal("PAM: authentication thread exited unexpectedly");
 128         if (WEXITSTATUS(sshpam_thread_status) != 0)
 129                 fatal("PAM: authentication thread exited uncleanly");
 130 }
 131
 132 static void
 133 pthread_exit(void *value __unused)
 134 {
 135         _exit(0);
 136 }
 137
 138 static int
 139 pthread_create(sp_pthread_t *thread, const void *attr __unused,
 140     void *(*thread_start)(void *), void *arg)
 141 {
 142         pid_t pid;
 143
 144         sshpam_thread_status = -1;
 145         switch ((pid = fork())) {
 146         case -1:
 147                 error("fork(): %s", strerror(errno));
 148                 return (-1);
 149         case 0:
 150                 thread_start(arg);
 151                 _exit(1);
 152         default:
 153                 *thread = pid;
 154                 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
 155                 return (0);
 156         }
 157 }
 158
 159 static int
 160 pthread_cancel(sp_pthread_t thread)
 161 {
 162         signal(SIGCHLD, sshpam_oldsig);
 163         return (kill(thread, SIGTERM));
 164 }
 165
 166 static int
 167 pthread_join(sp_pthread_t thread, void **value __unused)
 168 {
 169         int status;
 170
 171         if (sshpam_thread_status != -1)
 172                 return (sshpam_thread_status);
 173         signal(SIGCHLD, sshpam_oldsig);
 174         waitpid(thread, &status, 0);
 175         return (status);
 176 }
 177 #endif
 178
 179
 180 static pam_handle_t *sshpam_handle = NULL;
 181 static int sshpam_err = 0;
 182 static int sshpam_authenticated = 0;
 183 static int sshpam_session_open = 0;
 184 static int sshpam_cred_established = 0;
 185 static int sshpam_account_status = -1;
 186 static char **sshpam_env = NULL;
 187 static Authctxt *sshpam_authctxt = NULL;
 188 static const char *sshpam_password = NULL;
 189
 190 /* Some PAM implementations don't implement this */
 191 #ifndef HAVE_PAM_GETENVLIST
 192 static char **
 193 pam_getenvlist(pam_handle_t *pamh)
 194 {
 195         /*
 196          * XXX - If necessary, we can still support envrionment passing
 197          * for platforms without pam_getenvlist by searching for known
 198          * env vars (e.g. KRB5CCNAME) from the PAM environment.
 199          */
 200          return NULL;
 201 }
 202 #endif
 203
 204 void
 205 sshpam_password_change_required(int reqd)
 206 {
 207         debug3("%s %d", __func__, reqd);
 208         if (sshpam_authctxt == NULL)
 209                 fatal("%s: PAM authctxt not initialized", __func__);
 210         sshpam_authctxt->force_pwchange = reqd;
 211         if (reqd) {
 212                 no_port_forwarding_flag |= 2;
 213                 no_agent_forwarding_flag |= 2;
 214                 no_x11_forwarding_flag |= 2;
 215         } else {
 216                 no_port_forwarding_flag &= ~2;
 217                 no_agent_forwarding_flag &= ~2;
 218                 no_x11_forwarding_flag &= ~2;
 219         }
 220 }
 221
 222 /* Import regular and PAM environment from subprocess */
 223 static void
 224 import_environments(Buffer *b)
 225 {
 226         char *env;
 227         u_int i, num_env;
 228         int err;
 229
 230         debug3("PAM: %s entering", __func__);
 231
 232 #ifndef USE_POSIX_THREADS
 233         /* Import variables set by do_pam_account */
 234         sshpam_account_status = buffer_get_int(b);
 235         sshpam_password_change_required(buffer_get_int(b));
 236
 237         /* Import environment from subprocess */
 238         num_env = buffer_get_int(b);
 239         sshpam_env = xmalloc((num_env + 1) * sizeof(*sshpam_env));
 240         debug3("PAM: num env strings %d", num_env);
 241         for(i = 0; i < num_env; i++)
 242                 sshpam_env[i] = buffer_get_string(b, NULL);
 243
 244         sshpam_env[num_env] = NULL;
 245
 246         /* Import PAM environment from subprocess */
 247         num_env = buffer_get_int(b);
 248         debug("PAM: num PAM env strings %d", num_env);
 249         for(i = 0; i < num_env; i++) {
 250                 env = buffer_get_string(b, NULL);
 251
 252 #ifdef HAVE_PAM_PUTENV
 253                 /* Errors are not fatal here */
 254                 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
 255                         error("PAM: pam_putenv: %s",
 256                             pam_strerror(sshpam_handle, sshpam_err));
 257                 }
 258 #endif
 259         }
 260 #endif
 261 }
 262
 263 /*
 264  * Conversation function for authentication thread.
 265  */
 266 static int
 267 sshpam_thread_conv(int n, struct pam_message **msg,
 268     struct pam_response **resp, void *data)
 269 {
 270         Buffer buffer;
 271         struct pam_ctxt *ctxt;
 272         struct pam_response *reply;
 273         int i;
 274
 275         debug3("PAM: %s entering, %d messages", __func__, n);
 276         *resp = NULL;
 277
 278         if (data == NULL) {
 279                 error("PAM: conversation function passed a null context");
 280                 return (PAM_CONV_ERR);
 281         }
 282         ctxt = data;
 283         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 284                 return (PAM_CONV_ERR);
 285
 286         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 287                 return (PAM_CONV_ERR);
 288         memset(reply, 0, n * sizeof(*reply));
 289
 290         buffer_init(&buffer);
 291         for (i = 0; i < n; ++i) {
 292                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 293                 case PAM_PROMPT_ECHO_OFF:
 294                         buffer_put_cstring(&buffer,
 295                             PAM_MSG_MEMBER(msg, i, msg));
 296                         if (ssh_msg_send(ctxt->pam_csock,
 297                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 298                                 goto fail;
 299                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 300                                 goto fail;
 301                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 302                                 goto fail;
 303                         reply[i].resp = buffer_get_string(&buffer, NULL);
 304                         break;
 305                 case PAM_PROMPT_ECHO_ON:
 306                         buffer_put_cstring(&buffer,
 307                             PAM_MSG_MEMBER(msg, i, msg));
 308                         if (ssh_msg_send(ctxt->pam_csock,
 309                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 310                                 goto fail;
 311                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 312                                 goto fail;
 313                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 314                                 goto fail;
 315                         reply[i].resp = buffer_get_string(&buffer, NULL);
 316                         break;
 317                 case PAM_ERROR_MSG:
 318                         buffer_put_cstring(&buffer,
 319                             PAM_MSG_MEMBER(msg, i, msg));
 320                         if (ssh_msg_send(ctxt->pam_csock,
 321                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 322                                 goto fail;
 323                         break;
 324                 case PAM_TEXT_INFO:
 325                         buffer_put_cstring(&buffer,
 326                             PAM_MSG_MEMBER(msg, i, msg));
 327                         if (ssh_msg_send(ctxt->pam_csock,
 328                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 329                                 goto fail;
 330                         break;
 331                 default:
 332                         goto fail;
 333                 }
 334                 buffer_clear(&buffer);
 335         }
 336         buffer_free(&buffer);
 337         *resp = reply;
 338         return (PAM_SUCCESS);
 339
 340  fail:
 341         for(i = 0; i < n; i++) {
 342                 if (reply[i].resp != NULL)
 343                         xfree(reply[i].resp);
 344         }
 345         xfree(reply);
 346         buffer_free(&buffer);
 347         return (PAM_CONV_ERR);
 348 }
 349
 350 /*
 351  * Authentication thread.
 352  */
 353 static void *
 354 sshpam_thread(void *ctxtp)
 355 {
 356         struct pam_ctxt *ctxt = ctxtp;
 357         Buffer buffer;
 358         struct pam_conv sshpam_conv;
 359         int flags = (options.permit_empty_passwd == 0 ?
 360             PAM_DISALLOW_NULL_AUTHTOK : 0);
 361 #ifndef USE_POSIX_THREADS
 362         extern char **environ;
 363         char **env_from_pam;
 364         u_int i;
 365         const char *pam_user;
 366
 367         pam_get_item(sshpam_handle, PAM_USER, (void **)&pam_user);
 368         environ[0] = NULL;
 369
 370         if (sshpam_authctxt != NULL) {
 371                 setproctitle("%s [pam]",
 372                     sshpam_authctxt->valid ? pam_user : "unknown");
 373         }
 374 #endif
 375
 376         sshpam_conv.conv = sshpam_thread_conv;
 377         sshpam_conv.appdata_ptr = ctxt;
 378
 379         if (sshpam_authctxt == NULL)
 380                 fatal("%s: PAM authctxt not initialized", __func__);
 381
 382         buffer_init(&buffer);
 383         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 384             (const void *)&sshpam_conv);
 385         if (sshpam_err != PAM_SUCCESS)
 386                 goto auth_fail;
 387         sshpam_err = pam_authenticate(sshpam_handle, flags);
 388         if (sshpam_err != PAM_SUCCESS)
 389                 goto auth_fail;
 390
 391         if (compat20) {
 392                 if (!do_pam_account())
 393                         goto auth_fail;
 394                 if (sshpam_authctxt->force_pwchange) {
 395                         sshpam_err = pam_chauthtok(sshpam_handle,
 396                             PAM_CHANGE_EXPIRED_AUTHTOK);
 397                         if (sshpam_err != PAM_SUCCESS)
 398                                 goto auth_fail;
 399                         sshpam_password_change_required(0);
 400                 }
 401         }
 402
 403         buffer_put_cstring(&buffer, "OK");
 404
 405 #ifndef USE_POSIX_THREADS
 406         /* Export variables set by do_pam_account */
 407         buffer_put_int(&buffer, sshpam_account_status);
 408         buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);
 409
 410         /* Export any environment strings set in child */
 411         for(i = 0; environ[i] != NULL; i++)
 412                 ; /* Count */
 413         buffer_put_int(&buffer, i);
 414         for(i = 0; environ[i] != NULL; i++)
 415                 buffer_put_cstring(&buffer, environ[i]);
 416
 417         /* Export any environment strings set by PAM in child */
 418         env_from_pam = pam_getenvlist(sshpam_handle);
 419         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 420                 ; /* Count */
 421         buffer_put_int(&buffer, i);
 422         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 423                 buffer_put_cstring(&buffer, env_from_pam[i]);
 424 #endif /* USE_POSIX_THREADS */
 425
 426         /* XXX - can't do much about an error here */
 427         ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
 428         buffer_free(&buffer);
 429         pthread_exit(NULL);
 430
 431  auth_fail:
 432         buffer_put_cstring(&buffer,
 433             pam_strerror(sshpam_handle, sshpam_err));
 434         /* XXX - can't do much about an error here */
 435         ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
 436         buffer_free(&buffer);
 437         pthread_exit(NULL);
 438
 439         return (NULL); /* Avoid warning for non-pthread case */
 440 }
 441
 442 void
 443 sshpam_thread_cleanup(void)
 444 {
 445         struct pam_ctxt *ctxt = cleanup_ctxt;
 446
 447         debug3("PAM: %s entering", __func__);
 448         if (ctxt != NULL && ctxt->pam_thread != 0) {
 449                 pthread_cancel(ctxt->pam_thread);
 450                 pthread_join(ctxt->pam_thread, NULL);
 451                 close(ctxt->pam_psock);
 452                 close(ctxt->pam_csock);
 453                 memset(ctxt, 0, sizeof(*ctxt));
 454                 cleanup_ctxt = NULL;
 455         }
 456 }
 457
 458 static int
 459 sshpam_null_conv(int n, struct pam_message **msg,
 460     struct pam_response **resp, void *data)
 461 {
 462         debug3("PAM: %s entering, %d messages", __func__, n);
 463         return (PAM_CONV_ERR);
 464 }
 465
 466 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
 467
 468 void
 469 sshpam_cleanup(void)
 470 {
 471         debug("PAM: cleanup");
 472         if (sshpam_handle == NULL)
 473                 return;
 474         pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 475         if (sshpam_cred_established) {
 476                 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
 477                 sshpam_cred_established = 0;
 478         }
 479         if (sshpam_session_open) {
 480                 pam_close_session(sshpam_handle, PAM_SILENT);
 481                 sshpam_session_open = 0;
 482         }
 483         sshpam_authenticated = 0;
 484         pam_end(sshpam_handle, sshpam_err);
 485         sshpam_handle = NULL;
 486 }
 487
 488 static int
 489 sshpam_init(Authctxt *authctxt)
 490 {
 491         extern char *__progname;
 492         const char *pam_rhost, *pam_user, *user = authctxt->user;
 493
 494         if (sshpam_handle != NULL) {
 495                 /* We already have a PAM context; check if the user matches */
 496                 sshpam_err = pam_get_item(sshpam_handle,
 497                     PAM_USER, (void **)&pam_user);
 498                 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
 499                         return (0);
 500                 pam_end(sshpam_handle, sshpam_err);
 501                 sshpam_handle = NULL;
 502         }
 503         debug("PAM: initializing for \"%s\"", user);
 504         sshpam_err =
 505             pam_start(SSHD_PAM_SERVICE, user, &null_conv, &sshpam_handle);
 506         sshpam_authctxt = authctxt;
 507
 508         if (sshpam_err != PAM_SUCCESS) {
 509                 pam_end(sshpam_handle, sshpam_err);
 510                 sshpam_handle = NULL;
 511                 return (-1);
 512         }
 513         pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
 514         debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
 515         sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
 516         if (sshpam_err != PAM_SUCCESS) {
 517                 pam_end(sshpam_handle, sshpam_err);
 518                 sshpam_handle = NULL;
 519                 return (-1);
 520         }
 521 #ifdef PAM_TTY_KLUDGE
 522         /*
 523          * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
 524          * sshd doesn't set the tty until too late in the auth process and
 525          * may not even set one (for tty-less connections)
 526          */
 527         debug("PAM: setting PAM_TTY to \"ssh\"");
 528         sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
 529         if (sshpam_err != PAM_SUCCESS) {
 530                 pam_end(sshpam_handle, sshpam_err);
 531                 sshpam_handle = NULL;
 532                 return (-1);
 533         }
 534 #endif
 535         return (0);
 536 }
 537
 538 static void *
 539 sshpam_init_ctx(Authctxt *authctxt)
 540 {
 541         struct pam_ctxt *ctxt;
 542         int socks[2];
 543
 544         debug3("PAM: %s entering", __func__);
 545         /* Refuse to start if we don't have PAM enabled */
 546         if (!options.use_pam)
 547                 return NULL;
 548
 549         /* Initialize PAM */
 550         if (sshpam_init(authctxt) == -1) {
 551                 error("PAM: initialization failed");
 552                 return (NULL);
 553         }
 554
 555         ctxt = xmalloc(sizeof *ctxt);
 556         memset(ctxt, 0, sizeof(*ctxt));
 557
 558         /* Start the authentication thread */
 559         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
 560                 error("PAM: failed create sockets: %s", strerror(errno));
 561                 xfree(ctxt);
 562                 return (NULL);
 563         }
 564         ctxt->pam_psock = socks[0];
 565         ctxt->pam_csock = socks[1];
 566         if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
 567                 error("PAM: failed to start authentication thread: %s",
 568                     strerror(errno));
 569                 close(socks[0]);
 570                 close(socks[1]);
 571                 xfree(ctxt);
 572                 return (NULL);
 573         }
 574         cleanup_ctxt = ctxt;
 575         return (ctxt);
 576 }
 577
 578 static int
 579 sshpam_query(void *ctx, char **name, char **info,
 580     u_int *num, char ***prompts, u_int **echo_on)
 581 {
 582         Buffer buffer;
 583         struct pam_ctxt *ctxt = ctx;
 584         size_t plen;
 585         u_char type;
 586         char *msg;
 587         size_t len;
 588
 589         debug3("PAM: %s entering", __func__);
 590         buffer_init(&buffer);
 591         *name = xstrdup("");
 592         *info = xstrdup("");
 593         *prompts = xmalloc(sizeof(char *));
 594         **prompts = NULL;
 595         plen = 0;
 596         *echo_on = xmalloc(sizeof(u_int));
 597         while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
 598                 type = buffer_get_char(&buffer);
 599                 msg = buffer_get_string(&buffer, NULL);
 600                 switch (type) {
 601                 case PAM_PROMPT_ECHO_ON:
 602                 case PAM_PROMPT_ECHO_OFF:
 603                         *num = 1;
 604                         len = plen + strlen(msg) + 1;
 605                         **prompts = xrealloc(**prompts, len);
 606                         plen += snprintf(**prompts + plen, len, "%s", msg);
 607                         **echo_on = (type == PAM_PROMPT_ECHO_ON);
 608                         xfree(msg);
 609                         return (0);
 610                 case PAM_ERROR_MSG:
 611                 case PAM_TEXT_INFO:
 612                         /* accumulate messages */
 613                         len = plen + strlen(msg) + 2;
 614                         **prompts = xrealloc(**prompts, len);
 615                         plen += snprintf(**prompts + plen, len, "%s\n", msg);
 616                         xfree(msg);
 617                         break;
 618                 case PAM_SUCCESS:
 619                 case PAM_AUTH_ERR:
 620                         if (**prompts != NULL) {
 621                                 /* drain any accumulated messages */
 622                                 debug("PAM: %s", **prompts);
 623                                 buffer_append(&loginmsg, **prompts,
 624                                     strlen(**prompts));
 625                                 xfree(**prompts);
 626                                 **prompts = NULL;
 627                         }
 628                         if (type == PAM_SUCCESS) {
 629                                 import_environments(&buffer);
 630                                 *num = 0;
 631                                 **echo_on = 0;
 632                                 ctxt->pam_done = 1;
 633                                 xfree(msg);
 634                                 return (0);
 635                         }
 636                         error("PAM: %s for %s%.100s from %.100s", msg,
 637                             sshpam_authctxt->valid ? "" : "illegal user ",
 638                             sshpam_authctxt->user,
 639                             get_remote_name_or_ip(utmp_len, options.use_dns));
 640                         /* FALLTHROUGH */
 641                 default:
 642                         *num = 0;
 643                         **echo_on = 0;
 644                         xfree(msg);
 645                         ctxt->pam_done = -1;
 646                         return (-1);
 647                 }
 648         }
 649         return (-1);
 650 }
 651
 652 /* XXX - see also comment in auth-chall.c:verify_response */
 653 static int
 654 sshpam_respond(void *ctx, u_int num, char **resp)
 655 {
 656         Buffer buffer;
 657         struct pam_ctxt *ctxt = ctx;
 658
 659         debug2("PAM: %s entering, %d responses", __func__, num);
 660         switch (ctxt->pam_done) {
 661         case 1:
 662                 sshpam_authenticated = 1;
 663                 return (0);
 664         case 0:
 665                 break;
 666         default:
 667                 return (-1);
 668         }
 669         if (num != 1) {
 670                 error("PAM: expected one response, got %u", num);
 671                 return (-1);
 672         }
 673         buffer_init(&buffer);
 674         buffer_put_cstring(&buffer, *resp);
 675         if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
 676                 buffer_free(&buffer);
 677                 return (-1);
 678         }
 679         buffer_free(&buffer);
 680         return (1);
 681 }
 682
 683 static void
 684 sshpam_free_ctx(void *ctxtp)
 685 {
 686         struct pam_ctxt *ctxt = ctxtp;
 687
 688         debug3("PAM: %s entering", __func__);
 689         sshpam_thread_cleanup();
 690         xfree(ctxt);
 691         /*
 692          * We don't call sshpam_cleanup() here because we may need the PAM
 693          * handle at a later stage, e.g. when setting up a session.  It's
 694          * still on the cleanup list, so pam_end() *will* be called before
 695          * the server process terminates.
 696          */
 697 }
 698
 699 KbdintDevice sshpam_device = {
 700         "pam",
 701         sshpam_init_ctx,
 702         sshpam_query,
 703         sshpam_respond,
 704         sshpam_free_ctx
 705 };
 706
 707 KbdintDevice mm_sshpam_device = {
 708         "pam",
 709         mm_sshpam_init_ctx,
 710         mm_sshpam_query,
 711         mm_sshpam_respond,
 712         mm_sshpam_free_ctx
 713 };
 714
 715 /*
 716  * This replaces auth-pam.c
 717  */
 718 void
 719 start_pam(Authctxt *authctxt)
 720 {
 721         if (!options.use_pam)
 722                 fatal("PAM: initialisation requested when UsePAM=no");
 723
 724         if (sshpam_init(authctxt) == -1)
 725                 fatal("PAM: initialisation failed");
 726 }
 727
 728 void
 729 finish_pam(void)
 730 {
 731         sshpam_cleanup();
 732 }
 733
 734 u_int
 735 do_pam_account(void)
 736 {
 737         if (sshpam_account_status != -1)
 738                 return (sshpam_account_status);
 739
 740         sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
 741         debug3("PAM: %s pam_acct_mgmt = %d", __func__, sshpam_err);
 742
 743         if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
 744                 sshpam_account_status = 0;
 745                 return (sshpam_account_status);
 746         }
 747
 748         if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
 749                 sshpam_password_change_required(1);
 750
 751         sshpam_account_status = 1;
 752         return (sshpam_account_status);
 753 }
 754
 755 void
 756 do_pam_set_tty(const char *tty)
 757 {
 758         if (tty != NULL) {
 759                 debug("PAM: setting PAM_TTY to \"%s\"", tty);
 760                 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
 761                 if (sshpam_err != PAM_SUCCESS)
 762                         fatal("PAM: failed to set PAM_TTY: %s",
 763                             pam_strerror(sshpam_handle, sshpam_err));
 764         }
 765 }
 766
 767 void
 768 do_pam_setcred(int init)
 769 {
 770         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 771             (const void *)&null_conv);
 772         if (sshpam_err != PAM_SUCCESS)
 773                 fatal("PAM: failed to set PAM_CONV: %s",
 774                     pam_strerror(sshpam_handle, sshpam_err));
 775         if (init) {
 776                 debug("PAM: establishing credentials");
 777                 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
 778         } else {
 779                 debug("PAM: reinitializing credentials");
 780                 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
 781         }
 782         if (sshpam_err == PAM_SUCCESS) {
 783                 sshpam_cred_established = 1;
 784                 return;
 785         }
 786         if (sshpam_authenticated)
 787                 fatal("PAM: pam_setcred(): %s",
 788                     pam_strerror(sshpam_handle, sshpam_err));
 789         else
 790                 debug("PAM: pam_setcred(): %s",
 791                     pam_strerror(sshpam_handle, sshpam_err));
 792 }
 793
 794 static int
 795 sshpam_tty_conv(int n, struct pam_message **msg,
 796     struct pam_response **resp, void *data)
 797 {
 798         char input[PAM_MAX_MSG_SIZE];
 799         struct pam_response *reply;
 800         int i;
 801
 802         debug3("PAM: %s called with %d messages", __func__, n);
 803
 804         *resp = NULL;
 805
 806         if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
 807                 return (PAM_CONV_ERR);
 808
 809         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 810                 return (PAM_CONV_ERR);
 811         memset(reply, 0, n * sizeof(*reply));
 812
 813         for (i = 0; i < n; ++i) {
 814                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 815                 case PAM_PROMPT_ECHO_OFF:
 816                         reply[i].resp =
 817                             read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
 818                             RP_ALLOW_STDIN);
 819                         reply[i].resp_retcode = PAM_SUCCESS;
 820                         break;
 821                 case PAM_PROMPT_ECHO_ON:
 822                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 823                         fgets(input, sizeof input, stdin);
 824                         if ((reply[i].resp = strdup(input)) == NULL)
 825                                 goto fail;
 826                         reply[i].resp_retcode = PAM_SUCCESS;
 827                         break;
 828                 case PAM_ERROR_MSG:
 829                 case PAM_TEXT_INFO:
 830                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 831                         reply[i].resp_retcode = PAM_SUCCESS;
 832                         break;
 833                 default:
 834                         goto fail;
 835                 }
 836         }
 837         *resp = reply;
 838         return (PAM_SUCCESS);
 839
 840  fail:
 841         for(i = 0; i < n; i++) {
 842                 if (reply[i].resp != NULL)
 843                         xfree(reply[i].resp);
 844         }
 845         xfree(reply);
 846         return (PAM_CONV_ERR);
 847 }
 848
 849 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
 850
 851 /*
 852  * XXX this should be done in the authentication phase, but ssh1 doesn't
 853  * support that
 854  */
 855 void
 856 do_pam_chauthtok(void)
 857 {
 858         if (use_privsep)
 859                 fatal("Password expired (unable to change with privsep)");
 860         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 861             (const void *)&tty_conv);
 862         if (sshpam_err != PAM_SUCCESS)
 863                 fatal("PAM: failed to set PAM_CONV: %s",
 864                     pam_strerror(sshpam_handle, sshpam_err));
 865         debug("PAM: changing password");
 866         sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
 867         if (sshpam_err != PAM_SUCCESS)
 868                 fatal("PAM: pam_chauthtok(): %s",
 869                     pam_strerror(sshpam_handle, sshpam_err));
 870 }
 871
 872 static int
 873 sshpam_store_conv(int n, struct pam_message **msg,
 874     struct pam_response **resp, void *data)
 875 {
 876         struct pam_response *reply;
 877         int i;
 878         size_t len;
 879
 880         debug3("PAM: %s called with %d messages", __func__, n);
 881         *resp = NULL;
 882
 883         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 884                 return (PAM_CONV_ERR);
 885
 886         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 887                 return (PAM_CONV_ERR);
 888         memset(reply, 0, n * sizeof(*reply));
 889
 890         for (i = 0; i < n; ++i) {
 891                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 892                 case PAM_ERROR_MSG:
 893                 case PAM_TEXT_INFO:
 894                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
 895                         buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
 896                         buffer_append(&loginmsg, "\n", 1 );
 897                         reply[i].resp_retcode = PAM_SUCCESS;
 898                         break;
 899                 default:
 900                         goto fail;
 901                 }
 902         }
 903         *resp = reply;
 904         return (PAM_SUCCESS);
 905
 906  fail:
 907         for(i = 0; i < n; i++) {
 908                 if (reply[i].resp != NULL)
 909                         xfree(reply[i].resp);
 910         }
 911         xfree(reply);
 912         return (PAM_CONV_ERR);
 913 }
 914
 915 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
 916
 917 void
 918 do_pam_session(void)
 919 {
 920         debug3("PAM: opening session");
 921         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 922             (const void *)&store_conv);
 923         if (sshpam_err != PAM_SUCCESS)
 924                 fatal("PAM: failed to set PAM_CONV: %s",
 925                     pam_strerror(sshpam_handle, sshpam_err));
 926         sshpam_err = pam_open_session(sshpam_handle, 0);
 927         if (sshpam_err != PAM_SUCCESS)
 928                 fatal("PAM: pam_open_session(): %s",
 929                     pam_strerror(sshpam_handle, sshpam_err));
 930         sshpam_session_open = 1;
 931 }
 932
 933 /*
 934  * Set a PAM environment string. We need to do this so that the session
 935  * modules can handle things like Kerberos/GSI credentials that appear
 936  * during the ssh authentication process.
 937  */
 938 int
 939 do_pam_putenv(char *name, char *value)
 940 {
 941         int ret = 1;
 942 #ifdef HAVE_PAM_PUTENV
 943         char *compound;
 944         size_t len;
 945
 946         len = strlen(name) + strlen(value) + 2;
 947         compound = xmalloc(len);
 948
 949         snprintf(compound, len, "%s=%s", name, value);
 950         ret = pam_putenv(sshpam_handle, compound);
 951         xfree(compound);
 952 #endif
 953
 954         return (ret);
 955 }
 956
 957 char **
 958 fetch_pam_child_environment(void)
 959 {
 960         return sshpam_env;
 961 }
 962
 963 char **
 964 fetch_pam_environment(void)
 965 {
 966         return (pam_getenvlist(sshpam_handle));
 967 }
 968
 969 void
 970 free_pam_environment(char **env)
 971 {
 972         char **envp;
 973
 974         if (env == NULL)
 975                 return;
 976
 977         for (envp = env; *envp; envp++)
 978                 xfree(*envp);
 979         xfree(env);
 980 }
 981
 982 /*
 983  * "Blind" conversation function for password authentication.  Assumes that
 984  * echo-off prompts are for the password and stores messages for later
 985  * display.
 986  */
 987 static int
 988 sshpam_passwd_conv(int n, struct pam_message **msg,
 989     struct pam_response **resp, void *data)
 990 {
 991         struct pam_response *reply;
 992         int i;
 993         size_t len;
 994
 995         debug3("PAM: %s called with %d messages", __func__, n);
 996
 997         *resp = NULL;
 998
 999         if (n <= 0 || n > PAM_MAX_NUM_MSG)
1000                 return (PAM_CONV_ERR);
1001
1002         if ((reply = malloc(n * sizeof(*reply))) == NULL)
1003                 return (PAM_CONV_ERR);
1004         memset(reply, 0, n * sizeof(*reply));
1005
1006         for (i = 0; i < n; ++i) {
1007                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1008                 case PAM_PROMPT_ECHO_OFF:
1009                         if (sshpam_password == NULL)
1010                                 goto fail;
1011                         if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1012                                 goto fail;
1013                         reply[i].resp_retcode = PAM_SUCCESS;
1014                         break;
1015                 case PAM_ERROR_MSG:
1016                 case PAM_TEXT_INFO:
1017                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1018                         if (len > 0) {
1019                                 buffer_append(&loginmsg,
1020                                     PAM_MSG_MEMBER(msg, i, msg), len);
1021                                 buffer_append(&loginmsg, "\n", 1);
1022                         }
1023                         if ((reply[i].resp = strdup("")) == NULL)
1024                                 goto fail;
1025                         reply[i].resp_retcode = PAM_SUCCESS;
1026                         break;
1027                 default:
1028                         goto fail;
1029                 }
1030         }
1031         *resp = reply;
1032         return (PAM_SUCCESS);
1033
1034  fail:
1035         for(i = 0; i < n; i++) {
1036                 if (reply[i].resp != NULL)
1037                         xfree(reply[i].resp);
1038         }
1039         xfree(reply);
1040         return (PAM_CONV_ERR);
1041 }
1042
1043 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1044
1045 /*
1046  * Attempt password authentication via PAM
1047  */
1048 int
1049 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1050 {
1051         int flags = (options.permit_empty_passwd == 0 ?
1052             PAM_DISALLOW_NULL_AUTHTOK : 0);
1053         static char badpw[] = "\b\n\r\177INCORRECT";
1054
1055         if (!options.use_pam || sshpam_handle == NULL)
1056                 fatal("PAM: %s called when PAM disabled or failed to "
1057                     "initialise.", __func__);
1058
1059         sshpam_password = password;
1060         sshpam_authctxt = authctxt;
1061
1062         /*
1063          * If the user logging in is invalid, or is root but is not permitted
1064          * by PermitRootLogin, use an invalid password to prevent leaking
1065          * information via timing (eg if the PAM config has a delay on fail).
1066          */
1067         if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1068              options.permit_root_login != PERMIT_YES))
1069                 sshpam_password = badpw;
1070
1071         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1072             (const void *)&passwd_conv);
1073         if (sshpam_err != PAM_SUCCESS)
1074                 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1075                     pam_strerror(sshpam_handle, sshpam_err));
1076
1077         sshpam_err = pam_authenticate(sshpam_handle, flags);
1078         sshpam_password = NULL;
1079         if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1080                 debug("PAM: password authentication accepted for %.100s",
1081                     authctxt->user);
1082                return 1;
1083         } else {
1084                 debug("PAM: password authentication failed for %.100s: %s",
1085                     authctxt->valid ? authctxt->user : "an illegal user",
1086                     pam_strerror(sshpam_handle, sshpam_err));
1087                 return 0;
1088         }
1089 }
1090 #endif /* USE_PAM */