crypto/openssh-3.9p1/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: auth-pam.c,v 1.114 2004/08/16 13:12:06 dtucker Exp $");
  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 /*
 205  * Some platforms, notably Solaris, do not enforce password complexity
 206  * rules during pam_chauthtok() if the real uid of the calling process
 207  * is 0, on the assumption that it's being called by "passwd" run by root.
 208  * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
 209  * the right thing.
 210  */
 211 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
 212 static int
 213 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
 214 {
 215         int result;
 216
 217         if (sshpam_authctxt == NULL)
 218                 fatal("PAM: sshpam_authctxt not initialized");
 219         if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
 220                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 221         result = pam_chauthtok(pamh, flags);
 222         if (setreuid(0, -1) == -1)
 223                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 224         return result;
 225 }
 226 # define pam_chauthtok(a,b)     (sshpam_chauthtok_ruid((a), (b)))
 227 #endif
 228
 229 void
 230 sshpam_password_change_required(int reqd)
 231 {
 232         debug3("%s %d", __func__, reqd);
 233         if (sshpam_authctxt == NULL)
 234                 fatal("%s: PAM authctxt not initialized", __func__);
 235         sshpam_authctxt->force_pwchange = reqd;
 236         if (reqd) {
 237                 no_port_forwarding_flag |= 2;
 238                 no_agent_forwarding_flag |= 2;
 239                 no_x11_forwarding_flag |= 2;
 240         } else {
 241                 no_port_forwarding_flag &= ~2;
 242                 no_agent_forwarding_flag &= ~2;
 243                 no_x11_forwarding_flag &= ~2;
 244         }
 245 }
 246
 247 /* Import regular and PAM environment from subprocess */
 248 static void
 249 import_environments(Buffer *b)
 250 {
 251         char *env;
 252         u_int i, num_env;
 253         int err;
 254
 255         debug3("PAM: %s entering", __func__);
 256
 257 #ifndef USE_POSIX_THREADS
 258         /* Import variables set by do_pam_account */
 259         sshpam_account_status = buffer_get_int(b);
 260         sshpam_password_change_required(buffer_get_int(b));
 261
 262         /* Import environment from subprocess */
 263         num_env = buffer_get_int(b);
 264         sshpam_env = xmalloc((num_env + 1) * sizeof(*sshpam_env));
 265         debug3("PAM: num env strings %d", num_env);
 266         for(i = 0; i < num_env; i++)
 267                 sshpam_env[i] = buffer_get_string(b, NULL);
 268
 269         sshpam_env[num_env] = NULL;
 270
 271         /* Import PAM environment from subprocess */
 272         num_env = buffer_get_int(b);
 273         debug("PAM: num PAM env strings %d", num_env);
 274         for(i = 0; i < num_env; i++) {
 275                 env = buffer_get_string(b, NULL);
 276
 277 #ifdef HAVE_PAM_PUTENV
 278                 /* Errors are not fatal here */
 279                 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
 280                         error("PAM: pam_putenv: %s",
 281                             pam_strerror(sshpam_handle, sshpam_err));
 282                 }
 283 #endif
 284         }
 285 #endif
 286 }
 287
 288 /*
 289  * Conversation function for authentication thread.
 290  */
 291 static int
 292 sshpam_thread_conv(int n, struct pam_message **msg,
 293     struct pam_response **resp, void *data)
 294 {
 295         Buffer buffer;
 296         struct pam_ctxt *ctxt;
 297         struct pam_response *reply;
 298         int i;
 299
 300         debug3("PAM: %s entering, %d messages", __func__, n);
 301         *resp = NULL;
 302
 303         if (data == NULL) {
 304                 error("PAM: conversation function passed a null context");
 305                 return (PAM_CONV_ERR);
 306         }
 307         ctxt = data;
 308         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 309                 return (PAM_CONV_ERR);
 310
 311         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 312                 return (PAM_CONV_ERR);
 313         memset(reply, 0, n * sizeof(*reply));
 314
 315         buffer_init(&buffer);
 316         for (i = 0; i < n; ++i) {
 317                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 318                 case PAM_PROMPT_ECHO_OFF:
 319                         buffer_put_cstring(&buffer,
 320                             PAM_MSG_MEMBER(msg, i, msg));
 321                         if (ssh_msg_send(ctxt->pam_csock,
 322                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 323                                 goto fail;
 324                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 325                                 goto fail;
 326                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 327                                 goto fail;
 328                         reply[i].resp = buffer_get_string(&buffer, NULL);
 329                         break;
 330                 case PAM_PROMPT_ECHO_ON:
 331                         buffer_put_cstring(&buffer,
 332                             PAM_MSG_MEMBER(msg, i, msg));
 333                         if (ssh_msg_send(ctxt->pam_csock,
 334                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 335                                 goto fail;
 336                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 337                                 goto fail;
 338                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 339                                 goto fail;
 340                         reply[i].resp = buffer_get_string(&buffer, NULL);
 341                         break;
 342                 case PAM_ERROR_MSG:
 343                         buffer_put_cstring(&buffer,
 344                             PAM_MSG_MEMBER(msg, i, msg));
 345                         if (ssh_msg_send(ctxt->pam_csock,
 346                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 347                                 goto fail;
 348                         break;
 349                 case PAM_TEXT_INFO:
 350                         buffer_put_cstring(&buffer,
 351                             PAM_MSG_MEMBER(msg, i, msg));
 352                         if (ssh_msg_send(ctxt->pam_csock,
 353                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 354                                 goto fail;
 355                         break;
 356                 default:
 357                         goto fail;
 358                 }
 359                 buffer_clear(&buffer);
 360         }
 361         buffer_free(&buffer);
 362         *resp = reply;
 363         return (PAM_SUCCESS);
 364
 365  fail:
 366         for(i = 0; i < n; i++) {
 367                 if (reply[i].resp != NULL)
 368                         xfree(reply[i].resp);
 369         }
 370         xfree(reply);
 371         buffer_free(&buffer);
 372         return (PAM_CONV_ERR);
 373 }
 374
 375 /*
 376  * Authentication thread.
 377  */
 378 static void *
 379 sshpam_thread(void *ctxtp)
 380 {
 381         struct pam_ctxt *ctxt = ctxtp;
 382         Buffer buffer;
 383         struct pam_conv sshpam_conv;
 384         int flags = (options.permit_empty_passwd == 0 ?
 385             PAM_DISALLOW_NULL_AUTHTOK : 0);
 386 #ifndef USE_POSIX_THREADS
 387         extern char **environ;
 388         char **env_from_pam;
 389         u_int i;
 390         const char *pam_user;
 391
 392         pam_get_item(sshpam_handle, PAM_USER, (void **)&pam_user);
 393         environ[0] = NULL;
 394
 395         if (sshpam_authctxt != NULL) {
 396                 setproctitle("%s [pam]",
 397                     sshpam_authctxt->valid ? pam_user : "unknown");
 398         }
 399 #endif
 400
 401         sshpam_conv.conv = sshpam_thread_conv;
 402         sshpam_conv.appdata_ptr = ctxt;
 403
 404         if (sshpam_authctxt == NULL)
 405                 fatal("%s: PAM authctxt not initialized", __func__);
 406
 407         buffer_init(&buffer);
 408         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 409             (const void *)&sshpam_conv);
 410         if (sshpam_err != PAM_SUCCESS)
 411                 goto auth_fail;
 412         sshpam_err = pam_authenticate(sshpam_handle, flags);
 413         if (sshpam_err != PAM_SUCCESS)
 414                 goto auth_fail;
 415
 416         if (compat20) {
 417                 if (!do_pam_account())
 418                         goto auth_fail;
 419                 if (sshpam_authctxt->force_pwchange) {
 420                         sshpam_err = pam_chauthtok(sshpam_handle,
 421                             PAM_CHANGE_EXPIRED_AUTHTOK);
 422                         if (sshpam_err != PAM_SUCCESS)
 423                                 goto auth_fail;
 424                         sshpam_password_change_required(0);
 425                 }
 426         }
 427
 428         buffer_put_cstring(&buffer, "OK");
 429
 430 #ifndef USE_POSIX_THREADS
 431         /* Export variables set by do_pam_account */
 432         buffer_put_int(&buffer, sshpam_account_status);
 433         buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);
 434
 435         /* Export any environment strings set in child */
 436         for(i = 0; environ[i] != NULL; i++)
 437                 ; /* Count */
 438         buffer_put_int(&buffer, i);
 439         for(i = 0; environ[i] != NULL; i++)
 440                 buffer_put_cstring(&buffer, environ[i]);
 441
 442         /* Export any environment strings set by PAM in child */
 443         env_from_pam = pam_getenvlist(sshpam_handle);
 444         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 445                 ; /* Count */
 446         buffer_put_int(&buffer, i);
 447         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 448                 buffer_put_cstring(&buffer, env_from_pam[i]);
 449 #endif /* USE_POSIX_THREADS */
 450
 451         /* XXX - can't do much about an error here */
 452         ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
 453         buffer_free(&buffer);
 454         pthread_exit(NULL);
 455
 456  auth_fail:
 457         buffer_put_cstring(&buffer,
 458             pam_strerror(sshpam_handle, sshpam_err));
 459         /* XXX - can't do much about an error here */
 460         ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
 461         buffer_free(&buffer);
 462         pthread_exit(NULL);
 463
 464         return (NULL); /* Avoid warning for non-pthread case */
 465 }
 466
 467 void
 468 sshpam_thread_cleanup(void)
 469 {
 470         struct pam_ctxt *ctxt = cleanup_ctxt;
 471
 472         debug3("PAM: %s entering", __func__);
 473         if (ctxt != NULL && ctxt->pam_thread != 0) {
 474                 pthread_cancel(ctxt->pam_thread);
 475                 pthread_join(ctxt->pam_thread, NULL);
 476                 close(ctxt->pam_psock);
 477                 close(ctxt->pam_csock);
 478                 memset(ctxt, 0, sizeof(*ctxt));
 479                 cleanup_ctxt = NULL;
 480         }
 481 }
 482
 483 static int
 484 sshpam_null_conv(int n, struct pam_message **msg,
 485     struct pam_response **resp, void *data)
 486 {
 487         debug3("PAM: %s entering, %d messages", __func__, n);
 488         return (PAM_CONV_ERR);
 489 }
 490
 491 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
 492
 493 void
 494 sshpam_cleanup(void)
 495 {
 496         debug("PAM: cleanup");
 497         if (sshpam_handle == NULL)
 498                 return;
 499         pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 500         if (sshpam_cred_established) {
 501                 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
 502                 sshpam_cred_established = 0;
 503         }
 504         if (sshpam_session_open) {
 505                 pam_close_session(sshpam_handle, PAM_SILENT);
 506                 sshpam_session_open = 0;
 507         }
 508         sshpam_authenticated = 0;
 509         pam_end(sshpam_handle, sshpam_err);
 510         sshpam_handle = NULL;
 511 }
 512
 513 static int
 514 sshpam_init(Authctxt *authctxt)
 515 {
 516         extern char *__progname;
 517         const char *pam_rhost, *pam_user, *user = authctxt->user;
 518
 519         if (sshpam_handle != NULL) {
 520                 /* We already have a PAM context; check if the user matches */
 521                 sshpam_err = pam_get_item(sshpam_handle,
 522                     PAM_USER, (void **)&pam_user);
 523                 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
 524                         return (0);
 525                 pam_end(sshpam_handle, sshpam_err);
 526                 sshpam_handle = NULL;
 527         }
 528         debug("PAM: initializing for \"%s\"", user);
 529         sshpam_err =
 530             pam_start(SSHD_PAM_SERVICE, user, &null_conv, &sshpam_handle);
 531         sshpam_authctxt = authctxt;
 532
 533         if (sshpam_err != PAM_SUCCESS) {
 534                 pam_end(sshpam_handle, sshpam_err);
 535                 sshpam_handle = NULL;
 536                 return (-1);
 537         }
 538         pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
 539         debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
 540         sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
 541         if (sshpam_err != PAM_SUCCESS) {
 542                 pam_end(sshpam_handle, sshpam_err);
 543                 sshpam_handle = NULL;
 544                 return (-1);
 545         }
 546 #ifdef PAM_TTY_KLUDGE
 547         /*
 548          * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
 549          * sshd doesn't set the tty until too late in the auth process and
 550          * may not even set one (for tty-less connections)
 551          */
 552         debug("PAM: setting PAM_TTY to \"ssh\"");
 553         sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
 554         if (sshpam_err != PAM_SUCCESS) {
 555                 pam_end(sshpam_handle, sshpam_err);
 556                 sshpam_handle = NULL;
 557                 return (-1);
 558         }
 559 #endif
 560         return (0);
 561 }
 562
 563 static void *
 564 sshpam_init_ctx(Authctxt *authctxt)
 565 {
 566         struct pam_ctxt *ctxt;
 567         int socks[2];
 568
 569         debug3("PAM: %s entering", __func__);
 570         /* Refuse to start if we don't have PAM enabled */
 571         if (!options.use_pam)
 572                 return NULL;
 573
 574         /* Initialize PAM */
 575         if (sshpam_init(authctxt) == -1) {
 576                 error("PAM: initialization failed");
 577                 return (NULL);
 578         }
 579
 580         ctxt = xmalloc(sizeof *ctxt);
 581         memset(ctxt, 0, sizeof(*ctxt));
 582
 583         /* Start the authentication thread */
 584         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
 585                 error("PAM: failed create sockets: %s", strerror(errno));
 586                 xfree(ctxt);
 587                 return (NULL);
 588         }
 589         ctxt->pam_psock = socks[0];
 590         ctxt->pam_csock = socks[1];
 591         if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
 592                 error("PAM: failed to start authentication thread: %s",
 593                     strerror(errno));
 594                 close(socks[0]);
 595                 close(socks[1]);
 596                 xfree(ctxt);
 597                 return (NULL);
 598         }
 599         cleanup_ctxt = ctxt;
 600         return (ctxt);
 601 }
 602
 603 static int
 604 sshpam_query(void *ctx, char **name, char **info,
 605     u_int *num, char ***prompts, u_int **echo_on)
 606 {
 607         Buffer buffer;
 608         struct pam_ctxt *ctxt = ctx;
 609         size_t plen;
 610         u_char type;
 611         char *msg;
 612         size_t len;
 613
 614         debug3("PAM: %s entering", __func__);
 615         buffer_init(&buffer);
 616         *name = xstrdup("");
 617         *info = xstrdup("");
 618         *prompts = xmalloc(sizeof(char *));
 619         **prompts = NULL;
 620         plen = 0;
 621         *echo_on = xmalloc(sizeof(u_int));
 622         while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
 623                 type = buffer_get_char(&buffer);
 624                 msg = buffer_get_string(&buffer, NULL);
 625                 switch (type) {
 626                 case PAM_PROMPT_ECHO_ON:
 627                 case PAM_PROMPT_ECHO_OFF:
 628                         *num = 1;
 629                         len = plen + strlen(msg) + 1;
 630                         **prompts = xrealloc(**prompts, len);
 631                         plen += snprintf(**prompts + plen, len, "%s", msg);
 632                         **echo_on = (type == PAM_PROMPT_ECHO_ON);
 633                         xfree(msg);
 634                         return (0);
 635                 case PAM_ERROR_MSG:
 636                 case PAM_TEXT_INFO:
 637                         /* accumulate messages */
 638                         len = plen + strlen(msg) + 2;
 639                         **prompts = xrealloc(**prompts, len);
 640                         plen += snprintf(**prompts + plen, len, "%s\n", msg);
 641                         xfree(msg);
 642                         break;
 643                 case PAM_SUCCESS:
 644                 case PAM_AUTH_ERR:
 645                         if (**prompts != NULL) {
 646                                 /* drain any accumulated messages */
 647                                 debug("PAM: %s", **prompts);
 648                                 buffer_append(&loginmsg, **prompts,
 649                                     strlen(**prompts));
 650                                 xfree(**prompts);
 651                                 **prompts = NULL;
 652                         }
 653                         if (type == PAM_SUCCESS) {
 654                                 import_environments(&buffer);
 655                                 *num = 0;
 656                                 **echo_on = 0;
 657                                 ctxt->pam_done = 1;
 658                                 xfree(msg);
 659                                 return (0);
 660                         }
 661                         error("PAM: %s for %s%.100s from %.100s", msg,
 662                             sshpam_authctxt->valid ? "" : "illegal user ",
 663                             sshpam_authctxt->user,
 664                             get_remote_name_or_ip(utmp_len, options.use_dns));
 665                         /* FALLTHROUGH */
 666                 default:
 667                         *num = 0;
 668                         **echo_on = 0;
 669                         xfree(msg);
 670                         ctxt->pam_done = -1;
 671                         return (-1);
 672                 }
 673         }
 674         return (-1);
 675 }
 676
 677 /* XXX - see also comment in auth-chall.c:verify_response */
 678 static int
 679 sshpam_respond(void *ctx, u_int num, char **resp)
 680 {
 681         Buffer buffer;
 682         struct pam_ctxt *ctxt = ctx;
 683
 684         debug2("PAM: %s entering, %d responses", __func__, num);
 685         switch (ctxt->pam_done) {
 686         case 1:
 687                 sshpam_authenticated = 1;
 688                 return (0);
 689         case 0:
 690                 break;
 691         default:
 692                 return (-1);
 693         }
 694         if (num != 1) {
 695                 error("PAM: expected one response, got %u", num);
 696                 return (-1);
 697         }
 698         buffer_init(&buffer);
 699         buffer_put_cstring(&buffer, *resp);
 700         if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
 701                 buffer_free(&buffer);
 702                 return (-1);
 703         }
 704         buffer_free(&buffer);
 705         return (1);
 706 }
 707
 708 static void
 709 sshpam_free_ctx(void *ctxtp)
 710 {
 711         struct pam_ctxt *ctxt = ctxtp;
 712
 713         debug3("PAM: %s entering", __func__);
 714         sshpam_thread_cleanup();
 715         xfree(ctxt);
 716         /*
 717          * We don't call sshpam_cleanup() here because we may need the PAM
 718          * handle at a later stage, e.g. when setting up a session.  It's
 719          * still on the cleanup list, so pam_end() *will* be called before
 720          * the server process terminates.
 721          */
 722 }
 723
 724 KbdintDevice sshpam_device = {
 725         "pam",
 726         sshpam_init_ctx,
 727         sshpam_query,
 728         sshpam_respond,
 729         sshpam_free_ctx
 730 };
 731
 732 KbdintDevice mm_sshpam_device = {
 733         "pam",
 734         mm_sshpam_init_ctx,
 735         mm_sshpam_query,
 736         mm_sshpam_respond,
 737         mm_sshpam_free_ctx
 738 };
 739
 740 /*
 741  * This replaces auth-pam.c
 742  */
 743 void
 744 start_pam(Authctxt *authctxt)
 745 {
 746         if (!options.use_pam)
 747                 fatal("PAM: initialisation requested when UsePAM=no");
 748
 749         if (sshpam_init(authctxt) == -1)
 750                 fatal("PAM: initialisation failed");
 751 }
 752
 753 void
 754 finish_pam(void)
 755 {
 756         sshpam_cleanup();
 757 }
 758
 759 u_int
 760 do_pam_account(void)
 761 {
 762         if (sshpam_account_status != -1)
 763                 return (sshpam_account_status);
 764
 765         sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
 766         debug3("PAM: %s pam_acct_mgmt = %d", __func__, sshpam_err);
 767
 768         if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
 769                 sshpam_account_status = 0;
 770                 return (sshpam_account_status);
 771         }
 772
 773         if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
 774                 sshpam_password_change_required(1);
 775
 776         sshpam_account_status = 1;
 777         return (sshpam_account_status);
 778 }
 779
 780 void
 781 do_pam_set_tty(const char *tty)
 782 {
 783         if (tty != NULL) {
 784                 debug("PAM: setting PAM_TTY to \"%s\"", tty);
 785                 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
 786                 if (sshpam_err != PAM_SUCCESS)
 787                         fatal("PAM: failed to set PAM_TTY: %s",
 788                             pam_strerror(sshpam_handle, sshpam_err));
 789         }
 790 }
 791
 792 void
 793 do_pam_setcred(int init)
 794 {
 795         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 796             (const void *)&null_conv);
 797         if (sshpam_err != PAM_SUCCESS)
 798                 fatal("PAM: failed to set PAM_CONV: %s",
 799                     pam_strerror(sshpam_handle, sshpam_err));
 800         if (init) {
 801                 debug("PAM: establishing credentials");
 802                 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
 803         } else {
 804                 debug("PAM: reinitializing credentials");
 805                 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
 806         }
 807         if (sshpam_err == PAM_SUCCESS) {
 808                 sshpam_cred_established = 1;
 809                 return;
 810         }
 811         if (sshpam_authenticated)
 812                 fatal("PAM: pam_setcred(): %s",
 813                     pam_strerror(sshpam_handle, sshpam_err));
 814         else
 815                 debug("PAM: pam_setcred(): %s",
 816                     pam_strerror(sshpam_handle, sshpam_err));
 817 }
 818
 819 static int
 820 sshpam_tty_conv(int n, struct pam_message **msg,
 821     struct pam_response **resp, void *data)
 822 {
 823         char input[PAM_MAX_MSG_SIZE];
 824         struct pam_response *reply;
 825         int i;
 826
 827         debug3("PAM: %s called with %d messages", __func__, n);
 828
 829         *resp = NULL;
 830
 831         if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
 832                 return (PAM_CONV_ERR);
 833
 834         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 835                 return (PAM_CONV_ERR);
 836         memset(reply, 0, n * sizeof(*reply));
 837
 838         for (i = 0; i < n; ++i) {
 839                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 840                 case PAM_PROMPT_ECHO_OFF:
 841                         reply[i].resp =
 842                             read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
 843                             RP_ALLOW_STDIN);
 844                         reply[i].resp_retcode = PAM_SUCCESS;
 845                         break;
 846                 case PAM_PROMPT_ECHO_ON:
 847                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 848                         fgets(input, sizeof input, stdin);
 849                         if ((reply[i].resp = strdup(input)) == NULL)
 850                                 goto fail;
 851                         reply[i].resp_retcode = PAM_SUCCESS;
 852                         break;
 853                 case PAM_ERROR_MSG:
 854                 case PAM_TEXT_INFO:
 855                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 856                         reply[i].resp_retcode = PAM_SUCCESS;
 857                         break;
 858                 default:
 859                         goto fail;
 860                 }
 861         }
 862         *resp = reply;
 863         return (PAM_SUCCESS);
 864
 865  fail:
 866         for(i = 0; i < n; i++) {
 867                 if (reply[i].resp != NULL)
 868                         xfree(reply[i].resp);
 869         }
 870         xfree(reply);
 871         return (PAM_CONV_ERR);
 872 }
 873
 874 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
 875
 876 /*
 877  * XXX this should be done in the authentication phase, but ssh1 doesn't
 878  * support that
 879  */
 880 void
 881 do_pam_chauthtok(void)
 882 {
 883         if (use_privsep)
 884                 fatal("Password expired (unable to change with privsep)");
 885         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 886             (const void *)&tty_conv);
 887         if (sshpam_err != PAM_SUCCESS)
 888                 fatal("PAM: failed to set PAM_CONV: %s",
 889                     pam_strerror(sshpam_handle, sshpam_err));
 890         debug("PAM: changing password");
 891         sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
 892         if (sshpam_err != PAM_SUCCESS)
 893                 fatal("PAM: pam_chauthtok(): %s",
 894                     pam_strerror(sshpam_handle, sshpam_err));
 895 }
 896
 897 static int
 898 sshpam_store_conv(int n, struct pam_message **msg,
 899     struct pam_response **resp, void *data)
 900 {
 901         struct pam_response *reply;
 902         int i;
 903         size_t len;
 904
 905         debug3("PAM: %s called with %d messages", __func__, n);
 906         *resp = NULL;
 907
 908         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 909                 return (PAM_CONV_ERR);
 910
 911         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 912                 return (PAM_CONV_ERR);
 913         memset(reply, 0, n * sizeof(*reply));
 914
 915         for (i = 0; i < n; ++i) {
 916                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 917                 case PAM_ERROR_MSG:
 918                 case PAM_TEXT_INFO:
 919                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
 920                         buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
 921                         buffer_append(&loginmsg, "\n", 1 );
 922                         reply[i].resp_retcode = PAM_SUCCESS;
 923                         break;
 924                 default:
 925                         goto fail;
 926                 }
 927         }
 928         *resp = reply;
 929         return (PAM_SUCCESS);
 930
 931  fail:
 932         for(i = 0; i < n; i++) {
 933                 if (reply[i].resp != NULL)
 934                         xfree(reply[i].resp);
 935         }
 936         xfree(reply);
 937         return (PAM_CONV_ERR);
 938 }
 939
 940 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
 941
 942 void
 943 do_pam_session(void)
 944 {
 945         debug3("PAM: opening session");
 946         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 947             (const void *)&store_conv);
 948         if (sshpam_err != PAM_SUCCESS)
 949                 fatal("PAM: failed to set PAM_CONV: %s",
 950                     pam_strerror(sshpam_handle, sshpam_err));
 951         sshpam_err = pam_open_session(sshpam_handle, 0);
 952         if (sshpam_err != PAM_SUCCESS)
 953                 fatal("PAM: pam_open_session(): %s",
 954                     pam_strerror(sshpam_handle, sshpam_err));
 955         sshpam_session_open = 1;
 956 }
 957
 958 /*
 959  * Set a PAM environment string. We need to do this so that the session
 960  * modules can handle things like Kerberos/GSI credentials that appear
 961  * during the ssh authentication process.
 962  */
 963 int
 964 do_pam_putenv(char *name, char *value)
 965 {
 966         int ret = 1;
 967 #ifdef HAVE_PAM_PUTENV
 968         char *compound;
 969         size_t len;
 970
 971         len = strlen(name) + strlen(value) + 2;
 972         compound = xmalloc(len);
 973
 974         snprintf(compound, len, "%s=%s", name, value);
 975         ret = pam_putenv(sshpam_handle, compound);
 976         xfree(compound);
 977 #endif
 978
 979         return (ret);
 980 }
 981
 982 char **
 983 fetch_pam_child_environment(void)
 984 {
 985         return sshpam_env;
 986 }
 987
 988 char **
 989 fetch_pam_environment(void)
 990 {
 991         return (pam_getenvlist(sshpam_handle));
 992 }
 993
 994 void
 995 free_pam_environment(char **env)
 996 {
 997         char **envp;
 998
 999         if (env == NULL)
1000                 return;
1001
1002         for (envp = env; *envp; envp++)
1003                 xfree(*envp);
1004         xfree(env);
1005 }
1006
1007 /*
1008  * "Blind" conversation function for password authentication.  Assumes that
1009  * echo-off prompts are for the password and stores messages for later
1010  * display.
1011  */
1012 static int
1013 sshpam_passwd_conv(int n, struct pam_message **msg,
1014     struct pam_response **resp, void *data)
1015 {
1016         struct pam_response *reply;
1017         int i;
1018         size_t len;
1019
1020         debug3("PAM: %s called with %d messages", __func__, n);
1021
1022         *resp = NULL;
1023
1024         if (n <= 0 || n > PAM_MAX_NUM_MSG)
1025                 return (PAM_CONV_ERR);
1026
1027         if ((reply = malloc(n * sizeof(*reply))) == NULL)
1028                 return (PAM_CONV_ERR);
1029         memset(reply, 0, n * sizeof(*reply));
1030
1031         for (i = 0; i < n; ++i) {
1032                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1033                 case PAM_PROMPT_ECHO_OFF:
1034                         if (sshpam_password == NULL)
1035                                 goto fail;
1036                         if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1037                                 goto fail;
1038                         reply[i].resp_retcode = PAM_SUCCESS;
1039                         break;
1040                 case PAM_ERROR_MSG:
1041                 case PAM_TEXT_INFO:
1042                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1043                         if (len > 0) {
1044                                 buffer_append(&loginmsg,
1045                                     PAM_MSG_MEMBER(msg, i, msg), len);
1046                                 buffer_append(&loginmsg, "\n", 1);
1047                         }
1048                         if ((reply[i].resp = strdup("")) == NULL)
1049                                 goto fail;
1050                         reply[i].resp_retcode = PAM_SUCCESS;
1051                         break;
1052                 default:
1053                         goto fail;
1054                 }
1055         }
1056         *resp = reply;
1057         return (PAM_SUCCESS);
1058
1059  fail:
1060         for(i = 0; i < n; i++) {
1061                 if (reply[i].resp != NULL)
1062                         xfree(reply[i].resp);
1063         }
1064         xfree(reply);
1065         return (PAM_CONV_ERR);
1066 }
1067
1068 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1069
1070 /*
1071  * Attempt password authentication via PAM
1072  */
1073 int
1074 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1075 {
1076         int flags = (options.permit_empty_passwd == 0 ?
1077             PAM_DISALLOW_NULL_AUTHTOK : 0);
1078         static char badpw[] = "\b\n\r\177INCORRECT";
1079
1080         if (!options.use_pam || sshpam_handle == NULL)
1081                 fatal("PAM: %s called when PAM disabled or failed to "
1082                     "initialise.", __func__);
1083
1084         sshpam_password = password;
1085         sshpam_authctxt = authctxt;
1086
1087         /*
1088          * If the user logging in is invalid, or is root but is not permitted
1089          * by PermitRootLogin, use an invalid password to prevent leaking
1090          * information via timing (eg if the PAM config has a delay on fail).
1091          */
1092         if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1093              options.permit_root_login != PERMIT_YES))
1094                 sshpam_password = badpw;
1095
1096         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1097             (const void *)&passwd_conv);
1098         if (sshpam_err != PAM_SUCCESS)
1099                 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1100                     pam_strerror(sshpam_handle, sshpam_err));
1101
1102         sshpam_err = pam_authenticate(sshpam_handle, flags);
1103         sshpam_password = NULL;
1104         if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1105                 debug("PAM: password authentication accepted for %.100s",
1106                     authctxt->user);
1107                return 1;
1108         } else {
1109                 debug("PAM: password authentication failed for %.100s: %s",
1110                     authctxt->valid ? authctxt->user : "an illegal user",
1111                     pam_strerror(sshpam_handle, sshpam_err));
1112                 return 0;
1113         }
1114 }
1115 #endif /* USE_PAM */