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