auth-pam.c

   1 /*-
   2  * Copyright (c) 2002 Networks Associates Technology, Inc.
   3  * All rights reserved.
   4  *
   5  * This software was developed for the FreeBSD Project by ThinkSec AS and
   6  * NAI Labs, the Security Research Division of Network Associates, Inc.
   7  * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
   8  * DARPA CHATS research program.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31 /*
  32  * Copyright (c) 2003,2004 Damien Miller <djm@mindrot.org>
  33  * Copyright (c) 2003,2004 Darren Tucker <dtucker@zip.com.au>
  34  *
  35  * Permission to use, copy, modify, and distribute this software for any
  36  * purpose with or without fee is hereby granted, provided that the above
  37  * copyright notice and this permission notice appear in all copies.
  38  *
  39  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  40  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  41  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  42  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  43  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  44  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  45  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  46  */
  47
  48 /* Based on $FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des Exp $ */
  49 #include "includes.h"
  50 RCSID("$Id$");
  51
  52 #ifdef USE_PAM
  53 #if defined(HAVE_SECURITY_PAM_APPL_H)
  54 #include <security/pam_appl.h>
  55 #elif defined (HAVE_PAM_PAM_APPL_H)
  56 #include <pam/pam_appl.h>
  57 #endif
  58
  59 #include "auth.h"
  60 #include "auth-pam.h"
  61 #include "buffer.h"
  62 #include "bufaux.h"
  63 #include "canohost.h"
  64 #include "log.h"
  65 #include "monitor_wrap.h"
  66 #include "msg.h"
  67 #include "packet.h"
  68 #include "misc.h"
  69 #include "servconf.h"
  70 #include "ssh2.h"
  71 #include "xmalloc.h"
  72 #include "auth-options.h"
  73
  74 extern ServerOptions options;
  75 extern Buffer loginmsg;
  76 extern int compat20;
  77 extern u_int utmp_len;
  78
  79 #ifdef USE_POSIX_THREADS
  80 #include <pthread.h>
  81 /*
  82  * Avoid namespace clash when *not* using pthreads for systems *with*
  83  * pthreads, which unconditionally define pthread_t via sys/types.h
  84  * (e.g. Linux)
  85  */
  86 typedef pthread_t sp_pthread_t;
  87 #else
  88 typedef pid_t sp_pthread_t;
  89 #endif
  90
  91 struct pam_ctxt {
  92         sp_pthread_t     pam_thread;
  93         int              pam_psock;
  94         int              pam_csock;
  95         int              pam_done;
  96 };
  97
  98 static void sshpam_free_ctx(void *);
  99 static struct pam_ctxt *cleanup_ctxt;
 100
 101 #ifndef USE_POSIX_THREADS
 102 /*
 103  * Simulate threads with processes.
 104  */
 105
 106 static int sshpam_thread_status = -1;
 107 static mysig_t sshpam_oldsig;
 108
 109 static void
 110 sshpam_sigchld_handler(int sig)
 111 {
 112         signal(SIGCHLD, SIG_DFL);
 113         if (cleanup_ctxt == NULL)
 114                 return; /* handler called after PAM cleanup, shouldn't happen */
 115         if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
 116              <= 0) {
 117                 /* PAM thread has not exitted, privsep slave must have */
 118                 kill(cleanup_ctxt->pam_thread, SIGTERM);
 119                 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0)
 120                     <= 0)
 121                         return; /* could not wait */
 122         }
 123         if (WIFSIGNALED(sshpam_thread_status) &&
 124             WTERMSIG(sshpam_thread_status) == SIGTERM)
 125                 return; /* terminated by pthread_cancel */
 126         if (!WIFEXITED(sshpam_thread_status))
 127                 fatal("PAM: authentication thread exited unexpectedly");
 128         if (WEXITSTATUS(sshpam_thread_status) != 0)
 129                 fatal("PAM: authentication thread exited uncleanly");
 130 }
 131
 132 static void
 133 pthread_exit(void *value __unused)
 134 {
 135         _exit(0);
 136 }
 137
 138 static int
 139 pthread_create(sp_pthread_t *thread, const void *attr __unused,
 140     void *(*thread_start)(void *), void *arg)
 141 {
 142         pid_t pid;
 143
 144         sshpam_thread_status = -1;
 145         switch ((pid = fork())) {
 146         case -1:
 147                 error("fork(): %s", strerror(errno));
 148                 return (-1);
 149         case 0:
 150                 thread_start(arg);
 151                 _exit(1);
 152         default:
 153                 *thread = pid;
 154                 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
 155                 return (0);
 156         }
 157 }
 158
 159 static int
 160 pthread_cancel(sp_pthread_t thread)
 161 {
 162         signal(SIGCHLD, sshpam_oldsig);
 163         return (kill(thread, SIGTERM));
 164 }
 165
 166 static int
 167 pthread_join(sp_pthread_t thread, void **value __unused)
 168 {
 169         int status;
 170
 171         if (sshpam_thread_status != -1)
 172                 return (sshpam_thread_status);
 173         signal(SIGCHLD, sshpam_oldsig);
 174         waitpid(thread, &status, 0);
 175         return (status);
 176 }
 177 #endif
 178
 179
 180 static pam_handle_t *sshpam_handle = NULL;
 181 static int sshpam_err = 0;
 182 static int sshpam_authenticated = 0;
 183 static int sshpam_session_open = 0;
 184 static int sshpam_cred_established = 0;
 185 static int sshpam_account_status = -1;
 186 static char **sshpam_env = NULL;
 187 static Authctxt *sshpam_authctxt = NULL;
 188 static const char *sshpam_password = NULL;
 189
 190 /* Some PAM implementations don't implement this */
 191 #ifndef HAVE_PAM_GETENVLIST
 192 static char **
 193 pam_getenvlist(pam_handle_t *pamh)
 194 {
 195         /*
 196          * XXX - If necessary, we can still support envrionment passing
 197          * for platforms without pam_getenvlist by searching for known
 198          * env vars (e.g. KRB5CCNAME) from the PAM environment.
 199          */
 200          return NULL;
 201 }
 202 #endif
 203
 204 /*
 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 static int
 494 sshpam_store_conv(int n, struct pam_message **msg,
 495     struct pam_response **resp, void *data)
 496 {
 497         struct pam_response *reply;
 498         int i;
 499         size_t len;
 500
 501         debug3("PAM: %s called with %d messages", __func__, n);
 502         *resp = NULL;
 503
 504         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 505                 return (PAM_CONV_ERR);
 506
 507         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 508                 return (PAM_CONV_ERR);
 509         memset(reply, 0, n * sizeof(*reply));
 510
 511         for (i = 0; i < n; ++i) {
 512                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 513                 case PAM_ERROR_MSG:
 514                 case PAM_TEXT_INFO:
 515                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
 516                         buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
 517                         buffer_append(&loginmsg, "\n", 1 );
 518                         reply[i].resp_retcode = PAM_SUCCESS;
 519                         break;
 520                 default:
 521                         goto fail;
 522                 }
 523         }
 524         *resp = reply;
 525         return (PAM_SUCCESS);
 526
 527  fail:
 528         for(i = 0; i < n; i++) {
 529                 if (reply[i].resp != NULL)
 530                         xfree(reply[i].resp);
 531         }
 532         xfree(reply);
 533         return (PAM_CONV_ERR);
 534 }
 535
 536 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
 537
 538 void
 539 sshpam_cleanup(void)
 540 {
 541         debug("PAM: cleanup");
 542         if (sshpam_handle == NULL)
 543                 return;
 544         pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 545         if (sshpam_cred_established) {
 546                 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
 547                 sshpam_cred_established = 0;
 548         }
 549         if (sshpam_session_open) {
 550                 pam_close_session(sshpam_handle, PAM_SILENT);
 551                 sshpam_session_open = 0;
 552         }
 553         sshpam_authenticated = 0;
 554         pam_end(sshpam_handle, sshpam_err);
 555         sshpam_handle = NULL;
 556 }
 557
 558 static int
 559 sshpam_init(Authctxt *authctxt)
 560 {
 561         extern char *__progname;
 562         const char *pam_rhost, *pam_user, *user = authctxt->user;
 563
 564         if (sshpam_handle != NULL) {
 565                 /* We already have a PAM context; check if the user matches */
 566                 sshpam_err = pam_get_item(sshpam_handle,
 567                     PAM_USER, (void **)&pam_user);
 568                 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
 569                         return (0);
 570                 pam_end(sshpam_handle, sshpam_err);
 571                 sshpam_handle = NULL;
 572         }
 573         debug("PAM: initializing for \"%s\"", user);
 574         sshpam_err =
 575             pam_start(SSHD_PAM_SERVICE, user, &null_conv, &sshpam_handle);
 576         sshpam_authctxt = authctxt;
 577
 578         if (sshpam_err != PAM_SUCCESS) {
 579                 pam_end(sshpam_handle, sshpam_err);
 580                 sshpam_handle = NULL;
 581                 return (-1);
 582         }
 583         pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
 584         debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
 585         sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
 586         if (sshpam_err != PAM_SUCCESS) {
 587                 pam_end(sshpam_handle, sshpam_err);
 588                 sshpam_handle = NULL;
 589                 return (-1);
 590         }
 591 #ifdef PAM_TTY_KLUDGE
 592         /*
 593          * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
 594          * sshd doesn't set the tty until too late in the auth process and
 595          * may not even set one (for tty-less connections)
 596          */
 597         debug("PAM: setting PAM_TTY to \"ssh\"");
 598         sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
 599         if (sshpam_err != PAM_SUCCESS) {
 600                 pam_end(sshpam_handle, sshpam_err);
 601                 sshpam_handle = NULL;
 602                 return (-1);
 603         }
 604 #endif
 605         return (0);
 606 }
 607
 608 static void *
 609 sshpam_init_ctx(Authctxt *authctxt)
 610 {
 611         struct pam_ctxt *ctxt;
 612         int socks[2];
 613
 614         debug3("PAM: %s entering", __func__);
 615         /* Refuse to start if we don't have PAM enabled */
 616         if (!options.use_pam)
 617                 return NULL;
 618
 619         /* Initialize PAM */
 620         if (sshpam_init(authctxt) == -1) {
 621                 error("PAM: initialization failed");
 622                 return (NULL);
 623         }
 624
 625         ctxt = xmalloc(sizeof *ctxt);
 626         memset(ctxt, 0, sizeof(*ctxt));
 627
 628         /* Start the authentication thread */
 629         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
 630                 error("PAM: failed create sockets: %s", strerror(errno));
 631                 xfree(ctxt);
 632                 return (NULL);
 633         }
 634         ctxt->pam_psock = socks[0];
 635         ctxt->pam_csock = socks[1];
 636         if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
 637                 error("PAM: failed to start authentication thread: %s",
 638                     strerror(errno));
 639                 close(socks[0]);
 640                 close(socks[1]);
 641                 xfree(ctxt);
 642                 return (NULL);
 643         }
 644         cleanup_ctxt = ctxt;
 645         return (ctxt);
 646 }
 647
 648 static int
 649 sshpam_query(void *ctx, char **name, char **info,
 650     u_int *num, char ***prompts, u_int **echo_on)
 651 {
 652         Buffer buffer;
 653         struct pam_ctxt *ctxt = ctx;
 654         size_t plen;
 655         u_char type;
 656         char *msg;
 657         size_t len;
 658
 659         debug3("PAM: %s entering", __func__);
 660         buffer_init(&buffer);
 661         *name = xstrdup("");
 662         *info = xstrdup("");
 663         *prompts = xmalloc(sizeof(char *));
 664         **prompts = NULL;
 665         plen = 0;
 666         *echo_on = xmalloc(sizeof(u_int));
 667         while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
 668                 type = buffer_get_char(&buffer);
 669                 msg = buffer_get_string(&buffer, NULL);
 670                 switch (type) {
 671                 case PAM_PROMPT_ECHO_ON:
 672                 case PAM_PROMPT_ECHO_OFF:
 673                         *num = 1;
 674                         len = plen + strlen(msg) + 1;
 675                         **prompts = xrealloc(**prompts, len);
 676                         plen += snprintf(**prompts + plen, len, "%s", msg);
 677                         **echo_on = (type == PAM_PROMPT_ECHO_ON);
 678                         xfree(msg);
 679                         return (0);
 680                 case PAM_ERROR_MSG:
 681                 case PAM_TEXT_INFO:
 682                         /* accumulate messages */
 683                         len = plen + strlen(msg) + 2;
 684                         **prompts = xrealloc(**prompts, len);
 685                         plen += snprintf(**prompts + plen, len, "%s\n", msg);
 686                         xfree(msg);
 687                         break;
 688                 case PAM_SUCCESS:
 689                 case PAM_AUTH_ERR:
 690                         if (**prompts != NULL) {
 691                                 /* drain any accumulated messages */
 692                                 debug("PAM: %s", **prompts);
 693                                 buffer_append(&loginmsg, **prompts,
 694                                     strlen(**prompts));
 695                                 xfree(**prompts);
 696                                 **prompts = NULL;
 697                         }
 698                         if (type == PAM_SUCCESS) {
 699                                 import_environments(&buffer);
 700                                 *num = 0;
 701                                 **echo_on = 0;
 702                                 ctxt->pam_done = 1;
 703                                 xfree(msg);
 704                                 return (0);
 705                         }
 706                         error("PAM: %s for %s%.100s from %.100s", msg,
 707                             sshpam_authctxt->valid ? "" : "illegal user ",
 708                             sshpam_authctxt->user,
 709                             get_remote_name_or_ip(utmp_len, options.use_dns));
 710                         /* FALLTHROUGH */
 711                 default:
 712                         *num = 0;
 713                         **echo_on = 0;
 714                         xfree(msg);
 715                         ctxt->pam_done = -1;
 716                         return (-1);
 717                 }
 718         }
 719         return (-1);
 720 }
 721
 722 /* XXX - see also comment in auth-chall.c:verify_response */
 723 static int
 724 sshpam_respond(void *ctx, u_int num, char **resp)
 725 {
 726         Buffer buffer;
 727         struct pam_ctxt *ctxt = ctx;
 728
 729         debug2("PAM: %s entering, %d responses", __func__, num);
 730         switch (ctxt->pam_done) {
 731         case 1:
 732                 sshpam_authenticated = 1;
 733                 return (0);
 734         case 0:
 735                 break;
 736         default:
 737                 return (-1);
 738         }
 739         if (num != 1) {
 740                 error("PAM: expected one response, got %u", num);
 741                 return (-1);
 742         }
 743         buffer_init(&buffer);
 744         buffer_put_cstring(&buffer, *resp);
 745         if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
 746                 buffer_free(&buffer);
 747                 return (-1);
 748         }
 749         buffer_free(&buffer);
 750         return (1);
 751 }
 752
 753 static void
 754 sshpam_free_ctx(void *ctxtp)
 755 {
 756         struct pam_ctxt *ctxt = ctxtp;
 757
 758         debug3("PAM: %s entering", __func__);
 759         sshpam_thread_cleanup();
 760         xfree(ctxt);
 761         /*
 762          * We don't call sshpam_cleanup() here because we may need the PAM
 763          * handle at a later stage, e.g. when setting up a session.  It's
 764          * still on the cleanup list, so pam_end() *will* be called before
 765          * the server process terminates.
 766          */
 767 }
 768
 769 KbdintDevice sshpam_device = {
 770         "pam",
 771         sshpam_init_ctx,
 772         sshpam_query,
 773         sshpam_respond,
 774         sshpam_free_ctx
 775 };
 776
 777 KbdintDevice mm_sshpam_device = {
 778         "pam",
 779         mm_sshpam_init_ctx,
 780         mm_sshpam_query,
 781         mm_sshpam_respond,
 782         mm_sshpam_free_ctx
 783 };
 784
 785 /*
 786  * This replaces auth-pam.c
 787  */
 788 void
 789 start_pam(Authctxt *authctxt)
 790 {
 791         if (!options.use_pam)
 792                 fatal("PAM: initialisation requested when UsePAM=no");
 793
 794         if (sshpam_init(authctxt) == -1)
 795                 fatal("PAM: initialisation failed");
 796 }
 797
 798 void
 799 finish_pam(void)
 800 {
 801         sshpam_cleanup();
 802 }
 803
 804 u_int
 805 do_pam_account(void)
 806 {
 807         if (sshpam_account_status != -1)
 808                 return (sshpam_account_status);
 809
 810         sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
 811         debug3("PAM: %s pam_acct_mgmt = %d", __func__, sshpam_err);
 812
 813         if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
 814                 sshpam_account_status = 0;
 815                 return (sshpam_account_status);
 816         }
 817
 818         if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
 819                 sshpam_password_change_required(1);
 820
 821         sshpam_account_status = 1;
 822         return (sshpam_account_status);
 823 }
 824
 825 void
 826 do_pam_set_tty(const char *tty)
 827 {
 828         if (tty != NULL) {
 829                 debug("PAM: setting PAM_TTY to \"%s\"", tty);
 830                 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
 831                 if (sshpam_err != PAM_SUCCESS)
 832                         fatal("PAM: failed to set PAM_TTY: %s",
 833                             pam_strerror(sshpam_handle, sshpam_err));
 834         }
 835 }
 836
 837 void
 838 do_pam_setcred(int init)
 839 {
 840         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 841             (const void *)&null_conv);
 842         if (sshpam_err != PAM_SUCCESS)
 843                 fatal("PAM: failed to set PAM_CONV: %s",
 844                     pam_strerror(sshpam_handle, sshpam_err));
 845         if (init) {
 846                 debug("PAM: establishing credentials");
 847                 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
 848         } else {
 849                 debug("PAM: reinitializing credentials");
 850                 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
 851         }
 852         if (sshpam_err == PAM_SUCCESS) {
 853                 sshpam_cred_established = 1;
 854                 return;
 855         }
 856         if (sshpam_authenticated)
 857                 fatal("PAM: pam_setcred(): %s",
 858                     pam_strerror(sshpam_handle, sshpam_err));
 859         else
 860                 debug("PAM: pam_setcred(): %s",
 861                     pam_strerror(sshpam_handle, sshpam_err));
 862 }
 863
 864 static int
 865 sshpam_tty_conv(int n, struct pam_message **msg,
 866     struct pam_response **resp, void *data)
 867 {
 868         char input[PAM_MAX_MSG_SIZE];
 869         struct pam_response *reply;
 870         int i;
 871
 872         debug3("PAM: %s called with %d messages", __func__, n);
 873
 874         *resp = NULL;
 875
 876         if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
 877                 return (PAM_CONV_ERR);
 878
 879         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 880                 return (PAM_CONV_ERR);
 881         memset(reply, 0, n * sizeof(*reply));
 882
 883         for (i = 0; i < n; ++i) {
 884                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 885                 case PAM_PROMPT_ECHO_OFF:
 886                         reply[i].resp =
 887                             read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
 888                             RP_ALLOW_STDIN);
 889                         reply[i].resp_retcode = PAM_SUCCESS;
 890                         break;
 891                 case PAM_PROMPT_ECHO_ON:
 892                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 893                         fgets(input, sizeof input, stdin);
 894                         if ((reply[i].resp = strdup(input)) == NULL)
 895                                 goto fail;
 896                         reply[i].resp_retcode = PAM_SUCCESS;
 897                         break;
 898                 case PAM_ERROR_MSG:
 899                 case PAM_TEXT_INFO:
 900                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 901                         reply[i].resp_retcode = PAM_SUCCESS;
 902                         break;
 903                 default:
 904                         goto fail;
 905                 }
 906         }
 907         *resp = reply;
 908         return (PAM_SUCCESS);
 909
 910  fail:
 911         for(i = 0; i < n; i++) {
 912                 if (reply[i].resp != NULL)
 913                         xfree(reply[i].resp);
 914         }
 915         xfree(reply);
 916         return (PAM_CONV_ERR);
 917 }
 918
 919 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
 920
 921 /*
 922  * XXX this should be done in the authentication phase, but ssh1 doesn't
 923  * support that
 924  */
 925 void
 926 do_pam_chauthtok(void)
 927 {
 928         if (use_privsep)
 929                 fatal("Password expired (unable to change with privsep)");
 930         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 931             (const void *)&tty_conv);
 932         if (sshpam_err != PAM_SUCCESS)
 933                 fatal("PAM: failed to set PAM_CONV: %s",
 934                     pam_strerror(sshpam_handle, sshpam_err));
 935         debug("PAM: changing password");
 936         sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
 937         if (sshpam_err != PAM_SUCCESS)
 938                 fatal("PAM: pam_chauthtok(): %s",
 939                     pam_strerror(sshpam_handle, sshpam_err));
 940 }
 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                 sshpam_session_open = 1;
 954         else {
 955                 sshpam_session_open = 0;
 956                 disable_forwarding();
 957                 error("PAM: pam_open_session(): %s",
 958                     pam_strerror(sshpam_handle, sshpam_err));
 959         }
 960
 961 }
 962
 963 int
 964 is_pam_session_open(void)
 965 {
 966         return sshpam_session_open;
 967 }
 968
 969 /*
 970  * Set a PAM environment string. We need to do this so that the session
 971  * modules can handle things like Kerberos/GSI credentials that appear
 972  * during the ssh authentication process.
 973  */
 974 int
 975 do_pam_putenv(char *name, char *value)
 976 {
 977         int ret = 1;
 978 #ifdef HAVE_PAM_PUTENV
 979         char *compound;
 980         size_t len;
 981
 982         len = strlen(name) + strlen(value) + 2;
 983         compound = xmalloc(len);
 984
 985         snprintf(compound, len, "%s=%s", name, value);
 986         ret = pam_putenv(sshpam_handle, compound);
 987         xfree(compound);
 988 #endif
 989
 990         return (ret);
 991 }
 992
 993 char **
 994 fetch_pam_child_environment(void)
 995 {
 996         return sshpam_env;
 997 }
 998
 999 char **
1000 fetch_pam_environment(void)
1001 {
1002         return (pam_getenvlist(sshpam_handle));
1003 }
1004
1005 void
1006 free_pam_environment(char **env)
1007 {
1008         char **envp;
1009
1010         if (env == NULL)
1011                 return;
1012
1013         for (envp = env; *envp; envp++)
1014                 xfree(*envp);
1015         xfree(env);
1016 }
1017
1018 /*
1019  * "Blind" conversation function for password authentication.  Assumes that
1020  * echo-off prompts are for the password and stores messages for later
1021  * display.
1022  */
1023 static int
1024 sshpam_passwd_conv(int n, struct pam_message **msg,
1025     struct pam_response **resp, void *data)
1026 {
1027         struct pam_response *reply;
1028         int i;
1029         size_t len;
1030
1031         debug3("PAM: %s called with %d messages", __func__, n);
1032
1033         *resp = NULL;
1034
1035         if (n <= 0 || n > PAM_MAX_NUM_MSG)
1036                 return (PAM_CONV_ERR);
1037
1038         if ((reply = malloc(n * sizeof(*reply))) == NULL)
1039                 return (PAM_CONV_ERR);
1040         memset(reply, 0, n * sizeof(*reply));
1041
1042         for (i = 0; i < n; ++i) {
1043                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1044                 case PAM_PROMPT_ECHO_OFF:
1045                         if (sshpam_password == NULL)
1046                                 goto fail;
1047                         if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1048                                 goto fail;
1049                         reply[i].resp_retcode = PAM_SUCCESS;
1050                         break;
1051                 case PAM_ERROR_MSG:
1052                 case PAM_TEXT_INFO:
1053                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1054                         if (len > 0) {
1055                                 buffer_append(&loginmsg,
1056                                     PAM_MSG_MEMBER(msg, i, msg), len);
1057                                 buffer_append(&loginmsg, "\n", 1);
1058                         }
1059                         if ((reply[i].resp = strdup("")) == NULL)
1060                                 goto fail;
1061                         reply[i].resp_retcode = PAM_SUCCESS;
1062                         break;
1063                 default:
1064                         goto fail;
1065                 }
1066         }
1067         *resp = reply;
1068         return (PAM_SUCCESS);
1069
1070  fail:
1071         for(i = 0; i < n; i++) {
1072                 if (reply[i].resp != NULL)
1073                         xfree(reply[i].resp);
1074         }
1075         xfree(reply);
1076         return (PAM_CONV_ERR);
1077 }
1078
1079 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1080
1081 /*
1082  * Attempt password authentication via PAM
1083  */
1084 int
1085 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1086 {
1087         int flags = (options.permit_empty_passwd == 0 ?
1088             PAM_DISALLOW_NULL_AUTHTOK : 0);
1089         static char badpw[] = "\b\n\r\177INCORRECT";
1090
1091         if (!options.use_pam || sshpam_handle == NULL)
1092                 fatal("PAM: %s called when PAM disabled or failed to "
1093                     "initialise.", __func__);
1094
1095         sshpam_password = password;
1096         sshpam_authctxt = authctxt;
1097
1098         /*
1099          * If the user logging in is invalid, or is root but is not permitted
1100          * by PermitRootLogin, use an invalid password to prevent leaking
1101          * information via timing (eg if the PAM config has a delay on fail).
1102          */
1103         if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1104              options.permit_root_login != PERMIT_YES))
1105                 sshpam_password = badpw;
1106
1107         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1108             (const void *)&passwd_conv);
1109         if (sshpam_err != PAM_SUCCESS)
1110                 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1111                     pam_strerror(sshpam_handle, sshpam_err));
1112
1113         sshpam_err = pam_authenticate(sshpam_handle, flags);
1114         sshpam_password = NULL;
1115         if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1116                 debug("PAM: password authentication accepted for %.100s",
1117                     authctxt->user);
1118                return 1;
1119         } else {
1120                 debug("PAM: password authentication failed for %.100s: %s",
1121                     authctxt->valid ? authctxt->user : "an illegal user",
1122                     pam_strerror(sshpam_handle, sshpam_err));
1123                 return 0;
1124         }
1125 }
1126 #endif /* USE_PAM */