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