crypto/openssh-4/auth-pam.c

   1 /*-
   2  * Copyright (c) 2002 Networks Associates Technology, Inc.
   3  * All rights reserved.
   4  *
   5  * This software was developed for the FreeBSD Project by ThinkSec AS and
   6  * NAI Labs, the Security Research Division of Network Associates, Inc.
   7  * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
   8  * DARPA CHATS research program.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31 /*
  32  * Copyright (c) 2003,2004 Damien Miller <djm@mindrot.org>
  33  * Copyright (c) 2003,2004 Darren Tucker <dtucker@zip.com.au>
  34  *
  35  * Permission to use, copy, modify, and distribute this software for any
  36  * purpose with or without fee is hereby granted, provided that the above
  37  * copyright notice and this permission notice appear in all copies.
  38  *
  39  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  40  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  41  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  42  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  43  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  44  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  45  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  46  */
  47
  48 /* Based on $FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des Exp $ */
  49 #include "includes.h"
  50 RCSID("$Id: auth-pam.c,v 1.122 2005/05/25 06:18:10 dtucker Exp $");
  51
  52 #ifdef USE_PAM
  53 #if defined(HAVE_SECURITY_PAM_APPL_H)
  54 #include <security/pam_appl.h>
  55 #elif defined (HAVE_PAM_PAM_APPL_H)
  56 #include <pam/pam_appl.h>
  57 #endif
  58
  59 #include "auth.h"
  60 #include "auth-pam.h"
  61 #include "buffer.h"
  62 #include "bufaux.h"
  63 #include "canohost.h"
  64 #include "log.h"
  65 #include "monitor_wrap.h"
  66 #include "msg.h"
  67 #include "packet.h"
  68 #include "misc.h"
  69 #include "servconf.h"
  70 #include "ssh2.h"
  71 #include "xmalloc.h"
  72 #include "auth-options.h"
  73
  74 extern ServerOptions options;
  75 extern Buffer loginmsg;
  76 extern int compat20;
  77 extern u_int utmp_len;
  78
  79 /* so we don't silently change behaviour */
  80 #ifdef USE_POSIX_THREADS
  81 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
  82 #endif
  83
  84 /*
  85  * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
  86  * and generally a bad idea.  Use at own risk and do not expect support if
  87  * this breaks.
  88  */
  89 #ifdef UNSUPPORTED_POSIX_THREADS_HACK
  90 #include <pthread.h>
  91 /*
  92  * Avoid namespace clash when *not* using pthreads for systems *with*
  93  * pthreads, which unconditionally define pthread_t via sys/types.h
  94  * (e.g. Linux)
  95  */
  96 typedef pthread_t sp_pthread_t;
  97 #else
  98 typedef pid_t sp_pthread_t;
  99 #endif
 100
 101 struct pam_ctxt {
 102         sp_pthread_t     pam_thread;
 103         int              pam_psock;
 104         int              pam_csock;
 105         int              pam_done;
 106 };
 107
 108 static void sshpam_free_ctx(void *);
 109 static struct pam_ctxt *cleanup_ctxt;
 110
 111 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 112 /*
 113  * Simulate threads with processes.
 114  */
 115
 116 static int sshpam_thread_status = -1;
 117 static mysig_t sshpam_oldsig;
 118
 119 static void
 120 sshpam_sigchld_handler(int sig)
 121 {
 122         signal(SIGCHLD, SIG_DFL);
 123         if (cleanup_ctxt == NULL)
 124                 return; /* handler called after PAM cleanup, shouldn't happen */
 125         if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
 126              <= 0) {
 127                 /* PAM thread has not exitted, privsep slave must have */
 128                 kill(cleanup_ctxt->pam_thread, SIGTERM);
 129                 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0)
 130                     <= 0)
 131                         return; /* could not wait */
 132         }
 133         if (WIFSIGNALED(sshpam_thread_status) &&
 134             WTERMSIG(sshpam_thread_status) == SIGTERM)
 135                 return; /* terminated by pthread_cancel */
 136         if (!WIFEXITED(sshpam_thread_status))
 137                 fatal("PAM: authentication thread exited unexpectedly");
 138         if (WEXITSTATUS(sshpam_thread_status) != 0)
 139                 fatal("PAM: authentication thread exited uncleanly");
 140 }
 141
 142 static void
 143 pthread_exit(void *value __unused)
 144 {
 145         _exit(0);
 146 }
 147
 148 static int
 149 pthread_create(sp_pthread_t *thread, const void *attr __unused,
 150     void *(*thread_start)(void *), void *arg)
 151 {
 152         pid_t pid;
 153
 154         sshpam_thread_status = -1;
 155         switch ((pid = fork())) {
 156         case -1:
 157                 error("fork(): %s", strerror(errno));
 158                 return (-1);
 159         case 0:
 160                 thread_start(arg);
 161                 _exit(1);
 162         default:
 163                 *thread = pid;
 164                 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
 165                 return (0);
 166         }
 167 }
 168
 169 static int
 170 pthread_cancel(sp_pthread_t thread)
 171 {
 172         signal(SIGCHLD, sshpam_oldsig);
 173         return (kill(thread, SIGTERM));
 174 }
 175
 176 static int
 177 pthread_join(sp_pthread_t thread, void **value __unused)
 178 {
 179         int status;
 180
 181         if (sshpam_thread_status != -1)
 182                 return (sshpam_thread_status);
 183         signal(SIGCHLD, sshpam_oldsig);
 184         waitpid(thread, &status, 0);
 185         return (status);
 186 }
 187 #endif
 188
 189
 190 static pam_handle_t *sshpam_handle = NULL;
 191 static int sshpam_err = 0;
 192 static int sshpam_authenticated = 0;
 193 static int sshpam_session_open = 0;
 194 static int sshpam_cred_established = 0;
 195 static int sshpam_account_status = -1;
 196 static char **sshpam_env = NULL;
 197 static Authctxt *sshpam_authctxt = NULL;
 198 static const char *sshpam_password = NULL;
 199 static char badpw[] = "\b\n\r\177INCORRECT";
 200
 201 /* Some PAM implementations don't implement this */
 202 #ifndef HAVE_PAM_GETENVLIST
 203 static char **
 204 pam_getenvlist(pam_handle_t *pamh)
 205 {
 206         /*
 207          * XXX - If necessary, we can still support envrionment passing
 208          * for platforms without pam_getenvlist by searching for known
 209          * env vars (e.g. KRB5CCNAME) from the PAM environment.
 210          */
 211          return NULL;
 212 }
 213 #endif
 214
 215 /*
 216  * Some platforms, notably Solaris, do not enforce password complexity
 217  * rules during pam_chauthtok() if the real uid of the calling process
 218  * is 0, on the assumption that it's being called by "passwd" run by root.
 219  * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
 220  * the right thing.
 221  */
 222 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
 223 static int
 224 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
 225 {
 226         int result;
 227
 228         if (sshpam_authctxt == NULL)
 229                 fatal("PAM: sshpam_authctxt not initialized");
 230         if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
 231                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 232         result = pam_chauthtok(pamh, flags);
 233         if (setreuid(0, -1) == -1)
 234                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 235         return result;
 236 }
 237 # define pam_chauthtok(a,b)     (sshpam_chauthtok_ruid((a), (b)))
 238 #endif
 239
 240 void
 241 sshpam_password_change_required(int reqd)
 242 {
 243         debug3("%s %d", __func__, reqd);
 244         if (sshpam_authctxt == NULL)
 245                 fatal("%s: PAM authctxt not initialized", __func__);
 246         sshpam_authctxt->force_pwchange = reqd;
 247         if (reqd) {
 248                 no_port_forwarding_flag |= 2;
 249                 no_agent_forwarding_flag |= 2;
 250                 no_x11_forwarding_flag |= 2;
 251         } else {
 252                 no_port_forwarding_flag &= ~2;
 253                 no_agent_forwarding_flag &= ~2;
 254                 no_x11_forwarding_flag &= ~2;
 255         }
 256 }
 257
 258 /* Import regular and PAM environment from subprocess */
 259 static void
 260 import_environments(Buffer *b)
 261 {
 262         char *env;
 263         u_int i, num_env;
 264         int err;
 265
 266         debug3("PAM: %s entering", __func__);
 267
 268 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 269         /* Import variables set by do_pam_account */
 270         sshpam_account_status = buffer_get_int(b);
 271         sshpam_password_change_required(buffer_get_int(b));
 272
 273         /* Import environment from subprocess */
 274         num_env = buffer_get_int(b);
 275         sshpam_env = xmalloc((num_env + 1) * sizeof(*sshpam_env));
 276         debug3("PAM: num env strings %d", num_env);
 277         for(i = 0; i < num_env; i++)
 278                 sshpam_env[i] = buffer_get_string(b, NULL);
 279
 280         sshpam_env[num_env] = NULL;
 281
 282         /* Import PAM environment from subprocess */
 283         num_env = buffer_get_int(b);
 284         debug("PAM: num PAM env strings %d", num_env);
 285         for(i = 0; i < num_env; i++) {
 286                 env = buffer_get_string(b, NULL);
 287
 288 #ifdef HAVE_PAM_PUTENV
 289                 /* Errors are not fatal here */
 290                 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
 291                         error("PAM: pam_putenv: %s",
 292                             pam_strerror(sshpam_handle, sshpam_err));
 293                 }
 294 #endif
 295         }
 296 #endif
 297 }
 298
 299 /*
 300  * Conversation function for authentication thread.
 301  */
 302 static int
 303 sshpam_thread_conv(int n, struct pam_message **msg,
 304     struct pam_response **resp, void *data)
 305 {
 306         Buffer buffer;
 307         struct pam_ctxt *ctxt;
 308         struct pam_response *reply;
 309         int i;
 310
 311         debug3("PAM: %s entering, %d messages", __func__, n);
 312         *resp = NULL;
 313
 314         if (data == NULL) {
 315                 error("PAM: conversation function passed a null context");
 316                 return (PAM_CONV_ERR);
 317         }
 318         ctxt = data;
 319         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 320                 return (PAM_CONV_ERR);
 321
 322         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 323                 return (PAM_CONV_ERR);
 324         memset(reply, 0, n * sizeof(*reply));
 325
 326         buffer_init(&buffer);
 327         for (i = 0; i < n; ++i) {
 328                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 329                 case PAM_PROMPT_ECHO_OFF:
 330                         buffer_put_cstring(&buffer,
 331                             PAM_MSG_MEMBER(msg, i, msg));
 332                         if (ssh_msg_send(ctxt->pam_csock,
 333                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 334                                 goto fail;
 335                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 336                                 goto fail;
 337                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 338                                 goto fail;
 339                         reply[i].resp = buffer_get_string(&buffer, NULL);
 340                         break;
 341                 case PAM_PROMPT_ECHO_ON:
 342                         buffer_put_cstring(&buffer,
 343                             PAM_MSG_MEMBER(msg, i, msg));
 344                         if (ssh_msg_send(ctxt->pam_csock,
 345                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 346                                 goto fail;
 347                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 348                                 goto fail;
 349                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 350                                 goto fail;
 351                         reply[i].resp = buffer_get_string(&buffer, NULL);
 352                         break;
 353                 case PAM_ERROR_MSG:
 354                         buffer_put_cstring(&buffer,
 355                             PAM_MSG_MEMBER(msg, i, msg));
 356                         if (ssh_msg_send(ctxt->pam_csock,
 357                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 358                                 goto fail;
 359                         break;
 360                 case PAM_TEXT_INFO:
 361                         buffer_put_cstring(&buffer,
 362                             PAM_MSG_MEMBER(msg, i, msg));
 363                         if (ssh_msg_send(ctxt->pam_csock,
 364                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 365                                 goto fail;
 366                         break;
 367                 default:
 368                         goto fail;
 369                 }
 370                 buffer_clear(&buffer);
 371         }
 372         buffer_free(&buffer);
 373         *resp = reply;
 374         return (PAM_SUCCESS);
 375
 376  fail:
 377         for(i = 0; i < n; i++) {
 378                 if (reply[i].resp != NULL)
 379                         xfree(reply[i].resp);
 380         }
 381         xfree(reply);
 382         buffer_free(&buffer);
 383         return (PAM_CONV_ERR);
 384 }
 385
 386 /*
 387  * Authentication thread.
 388  */
 389 static void *
 390 sshpam_thread(void *ctxtp)
 391 {
 392         struct pam_ctxt *ctxt = ctxtp;
 393         Buffer buffer;
 394         struct pam_conv sshpam_conv;
 395         int flags = (options.permit_empty_passwd == 0 ?
 396             PAM_DISALLOW_NULL_AUTHTOK : 0);
 397 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 398         extern char **environ;
 399         char **env_from_pam;
 400         u_int i;
 401         const char *pam_user;
 402
 403         pam_get_item(sshpam_handle, PAM_USER, (void **)&pam_user);
 404         environ[0] = NULL;
 405
 406         if (sshpam_authctxt != NULL) {
 407                 setproctitle("%s [pam]",
 408                     sshpam_authctxt->valid ? pam_user : "unknown");
 409         }
 410 #endif
 411
 412         sshpam_conv.conv = sshpam_thread_conv;
 413         sshpam_conv.appdata_ptr = ctxt;
 414
 415         if (sshpam_authctxt == NULL)
 416                 fatal("%s: PAM authctxt not initialized", __func__);
 417
 418         buffer_init(&buffer);
 419         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 420             (const void *)&sshpam_conv);
 421         if (sshpam_err != PAM_SUCCESS)
 422                 goto auth_fail;
 423         sshpam_err = pam_authenticate(sshpam_handle, flags);
 424         if (sshpam_err != PAM_SUCCESS)
 425                 goto auth_fail;
 426
 427         if (compat20) {
 428                 if (!do_pam_account())
 429                         goto auth_fail;
 430                 if (sshpam_authctxt->force_pwchange) {
 431                         sshpam_err = pam_chauthtok(sshpam_handle,
 432                             PAM_CHANGE_EXPIRED_AUTHTOK);
 433                         if (sshpam_err != PAM_SUCCESS)
 434                                 goto auth_fail;
 435                         sshpam_password_change_required(0);
 436                 }
 437         }
 438
 439         buffer_put_cstring(&buffer, "OK");
 440
 441 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 442         /* Export variables set by do_pam_account */
 443         buffer_put_int(&buffer, sshpam_account_status);
 444         buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);
 445
 446         /* Export any environment strings set in child */
 447         for(i = 0; environ[i] != NULL; i++)
 448                 ; /* Count */
 449         buffer_put_int(&buffer, i);
 450         for(i = 0; environ[i] != NULL; i++)
 451                 buffer_put_cstring(&buffer, environ[i]);
 452
 453         /* Export any environment strings set by PAM in child */
 454         env_from_pam = pam_getenvlist(sshpam_handle);
 455         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 456                 ; /* Count */
 457         buffer_put_int(&buffer, i);
 458         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 459                 buffer_put_cstring(&buffer, env_from_pam[i]);
 460 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */
 461
 462         /* XXX - can't do much about an error here */
 463         ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
 464         buffer_free(&buffer);
 465         pthread_exit(NULL);
 466
 467  auth_fail:
 468         buffer_put_cstring(&buffer,
 469             pam_strerror(sshpam_handle, sshpam_err));
 470         /* XXX - can't do much about an error here */
 471         ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
 472         buffer_free(&buffer);
 473         pthread_exit(NULL);
 474
 475         return (NULL); /* Avoid warning for non-pthread case */
 476 }
 477
 478 void
 479 sshpam_thread_cleanup(void)
 480 {
 481         struct pam_ctxt *ctxt = cleanup_ctxt;
 482
 483         debug3("PAM: %s entering", __func__);
 484         if (ctxt != NULL && ctxt->pam_thread != 0) {
 485                 pthread_cancel(ctxt->pam_thread);
 486                 pthread_join(ctxt->pam_thread, NULL);
 487                 close(ctxt->pam_psock);
 488                 close(ctxt->pam_csock);
 489                 memset(ctxt, 0, sizeof(*ctxt));
 490                 cleanup_ctxt = NULL;
 491         }
 492 }
 493
 494 static int
 495 sshpam_null_conv(int n, struct pam_message **msg,
 496     struct pam_response **resp, void *data)
 497 {
 498         debug3("PAM: %s entering, %d messages", __func__, n);
 499         return (PAM_CONV_ERR);
 500 }
 501
 502 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
 503
 504 static int
 505 sshpam_store_conv(int n, struct pam_message **msg,
 506     struct pam_response **resp, void *data)
 507 {
 508         struct pam_response *reply;
 509         int i;
 510         size_t len;
 511
 512         debug3("PAM: %s called with %d messages", __func__, n);
 513         *resp = NULL;
 514
 515         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 516                 return (PAM_CONV_ERR);
 517
 518         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 519                 return (PAM_CONV_ERR);
 520         memset(reply, 0, n * sizeof(*reply));
 521
 522         for (i = 0; i < n; ++i) {
 523                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 524                 case PAM_ERROR_MSG:
 525                 case PAM_TEXT_INFO:
 526                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
 527                         buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
 528                         buffer_append(&loginmsg, "\n", 1 );
 529                         reply[i].resp_retcode = PAM_SUCCESS;
 530                         break;
 531                 default:
 532                         goto fail;
 533                 }
 534         }
 535         *resp = reply;
 536         return (PAM_SUCCESS);
 537
 538  fail:
 539         for(i = 0; i < n; i++) {
 540                 if (reply[i].resp != NULL)
 541                         xfree(reply[i].resp);
 542         }
 543         xfree(reply);
 544         return (PAM_CONV_ERR);
 545 }
 546
 547 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
 548
 549 void
 550 sshpam_cleanup(void)
 551 {
 552         debug("PAM: cleanup");
 553         if (sshpam_handle == NULL)
 554                 return;
 555         pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 556         if (sshpam_cred_established) {
 557                 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
 558                 sshpam_cred_established = 0;
 559         }
 560         if (sshpam_session_open) {
 561                 pam_close_session(sshpam_handle, PAM_SILENT);
 562                 sshpam_session_open = 0;
 563         }
 564         sshpam_authenticated = 0;
 565         pam_end(sshpam_handle, sshpam_err);
 566         sshpam_handle = NULL;
 567 }
 568
 569 static int
 570 sshpam_init(Authctxt *authctxt)
 571 {
 572         extern char *__progname;
 573         const char *pam_rhost, *pam_user, *user = authctxt->user;
 574
 575         if (sshpam_handle != NULL) {
 576                 /* We already have a PAM context; check if the user matches */
 577                 sshpam_err = pam_get_item(sshpam_handle,
 578                     PAM_USER, (void **)&pam_user);
 579                 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
 580                         return (0);
 581                 pam_end(sshpam_handle, sshpam_err);
 582                 sshpam_handle = NULL;
 583         }
 584         debug("PAM: initializing for \"%s\"", user);
 585         sshpam_err =
 586             pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
 587         sshpam_authctxt = authctxt;
 588
 589         if (sshpam_err != PAM_SUCCESS) {
 590                 pam_end(sshpam_handle, sshpam_err);
 591                 sshpam_handle = NULL;
 592                 return (-1);
 593         }
 594         pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
 595         debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
 596         sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
 597         if (sshpam_err != PAM_SUCCESS) {
 598                 pam_end(sshpam_handle, sshpam_err);
 599                 sshpam_handle = NULL;
 600                 return (-1);
 601         }
 602 #ifdef PAM_TTY_KLUDGE
 603         /*
 604          * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
 605          * sshd doesn't set the tty until too late in the auth process and
 606          * may not even set one (for tty-less connections)
 607          */
 608         debug("PAM: setting PAM_TTY to \"ssh\"");
 609         sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
 610         if (sshpam_err != PAM_SUCCESS) {
 611                 pam_end(sshpam_handle, sshpam_err);
 612                 sshpam_handle = NULL;
 613                 return (-1);
 614         }
 615 #endif
 616         return (0);
 617 }
 618
 619 static void *
 620 sshpam_init_ctx(Authctxt *authctxt)
 621 {
 622         struct pam_ctxt *ctxt;
 623         int socks[2];
 624
 625         debug3("PAM: %s entering", __func__);
 626         /* Refuse to start if we don't have PAM enabled */
 627         if (!options.use_pam)
 628                 return NULL;
 629
 630         /* Initialize PAM */
 631         if (sshpam_init(authctxt) == -1) {
 632                 error("PAM: initialization failed");
 633                 return (NULL);
 634         }
 635
 636         ctxt = xmalloc(sizeof *ctxt);
 637         memset(ctxt, 0, sizeof(*ctxt));
 638
 639         /* Start the authentication thread */
 640         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
 641                 error("PAM: failed create sockets: %s", strerror(errno));
 642                 xfree(ctxt);
 643                 return (NULL);
 644         }
 645         ctxt->pam_psock = socks[0];
 646         ctxt->pam_csock = socks[1];
 647         if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
 648                 error("PAM: failed to start authentication thread: %s",
 649                     strerror(errno));
 650                 close(socks[0]);
 651                 close(socks[1]);
 652                 xfree(ctxt);
 653                 return (NULL);
 654         }
 655         cleanup_ctxt = ctxt;
 656         return (ctxt);
 657 }
 658
 659 static int
 660 sshpam_query(void *ctx, char **name, char **info,
 661     u_int *num, char ***prompts, u_int **echo_on)
 662 {
 663         Buffer buffer;
 664         struct pam_ctxt *ctxt = ctx;
 665         size_t plen;
 666         u_char type;
 667         char *msg;
 668         size_t len, mlen;
 669
 670         debug3("PAM: %s entering", __func__);
 671         buffer_init(&buffer);
 672         *name = xstrdup("");
 673         *info = xstrdup("");
 674         *prompts = xmalloc(sizeof(char *));
 675         **prompts = NULL;
 676         plen = 0;
 677         *echo_on = xmalloc(sizeof(u_int));
 678         while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
 679                 type = buffer_get_char(&buffer);
 680                 msg = buffer_get_string(&buffer, NULL);
 681                 mlen = strlen(msg);
 682                 switch (type) {
 683                 case PAM_PROMPT_ECHO_ON:
 684                 case PAM_PROMPT_ECHO_OFF:
 685                         *num = 1;
 686                         len = plen + mlen + 1;
 687                         **prompts = xrealloc(**prompts, len);
 688                         strlcpy(**prompts + plen, msg, len - plen);
 689                         plen += mlen;
 690                         **echo_on = (type == PAM_PROMPT_ECHO_ON);
 691                         xfree(msg);
 692                         return (0);
 693                 case PAM_ERROR_MSG:
 694                 case PAM_TEXT_INFO:
 695                         /* accumulate messages */
 696                         len = plen + mlen + 2;
 697                         **prompts = xrealloc(**prompts, len);
 698                         strlcpy(**prompts + plen, msg, len - plen);
 699                         plen += mlen;
 700                         strlcat(**prompts + plen, "\n", len - plen);
 701                         plen++;
 702                         xfree(msg);
 703                         break;
 704                 case PAM_SUCCESS:
 705                 case PAM_AUTH_ERR:
 706                         if (**prompts != NULL) {
 707                                 /* drain any accumulated messages */
 708                                 debug("PAM: %s", **prompts);
 709                                 buffer_append(&loginmsg, **prompts,
 710                                     strlen(**prompts));
 711                                 xfree(**prompts);
 712                                 **prompts = NULL;
 713                         }
 714                         if (type == PAM_SUCCESS) {
 715                                 if (!sshpam_authctxt->valid ||
 716                                     (sshpam_authctxt->pw->pw_uid == 0 &&
 717                                     options.permit_root_login != PERMIT_YES))
 718                                         fatal("Internal error: PAM auth "
 719                                             "succeeded when it should have "
 720                                             "failed");
 721                                 import_environments(&buffer);
 722                                 *num = 0;
 723                                 **echo_on = 0;
 724                                 ctxt->pam_done = 1;
 725                                 xfree(msg);
 726                                 return (0);
 727                         }
 728                         error("PAM: %s for %s%.100s from %.100s", msg,
 729                             sshpam_authctxt->valid ? "" : "illegal user ",
 730                             sshpam_authctxt->user,
 731                             get_remote_name_or_ip(utmp_len, options.use_dns));
 732                         /* FALLTHROUGH */
 733                 default:
 734                         *num = 0;
 735                         **echo_on = 0;
 736                         xfree(msg);
 737                         ctxt->pam_done = -1;
 738                         return (-1);
 739                 }
 740         }
 741         return (-1);
 742 }
 743
 744 /* XXX - see also comment in auth-chall.c:verify_response */
 745 static int
 746 sshpam_respond(void *ctx, u_int num, char **resp)
 747 {
 748         Buffer buffer;
 749         struct pam_ctxt *ctxt = ctx;
 750
 751         debug2("PAM: %s entering, %d responses", __func__, num);
 752         switch (ctxt->pam_done) {
 753         case 1:
 754                 sshpam_authenticated = 1;
 755                 return (0);
 756         case 0:
 757                 break;
 758         default:
 759                 return (-1);
 760         }
 761         if (num != 1) {
 762                 error("PAM: expected one response, got %u", num);
 763                 return (-1);
 764         }
 765         buffer_init(&buffer);
 766         if (sshpam_authctxt->valid &&
 767             (sshpam_authctxt->pw->pw_uid != 0 ||
 768              options.permit_root_login == PERMIT_YES))
 769                 buffer_put_cstring(&buffer, *resp);
 770         else
 771                 buffer_put_cstring(&buffer, badpw);
 772         if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
 773                 buffer_free(&buffer);
 774                 return (-1);
 775         }
 776         buffer_free(&buffer);
 777         return (1);
 778 }
 779
 780 static void
 781 sshpam_free_ctx(void *ctxtp)
 782 {
 783         struct pam_ctxt *ctxt = ctxtp;
 784
 785         debug3("PAM: %s entering", __func__);
 786         sshpam_thread_cleanup();
 787         xfree(ctxt);
 788         /*
 789          * We don't call sshpam_cleanup() here because we may need the PAM
 790          * handle at a later stage, e.g. when setting up a session.  It's
 791          * still on the cleanup list, so pam_end() *will* be called before
 792          * the server process terminates.
 793          */
 794 }
 795
 796 KbdintDevice sshpam_device = {
 797         "pam",
 798         sshpam_init_ctx,
 799         sshpam_query,
 800         sshpam_respond,
 801         sshpam_free_ctx
 802 };
 803
 804 KbdintDevice mm_sshpam_device = {
 805         "pam",
 806         mm_sshpam_init_ctx,
 807         mm_sshpam_query,
 808         mm_sshpam_respond,
 809         mm_sshpam_free_ctx
 810 };
 811
 812 /*
 813  * This replaces auth-pam.c
 814  */
 815 void
 816 start_pam(Authctxt *authctxt)
 817 {
 818         if (!options.use_pam)
 819                 fatal("PAM: initialisation requested when UsePAM=no");
 820
 821         if (sshpam_init(authctxt) == -1)
 822                 fatal("PAM: initialisation failed");
 823 }
 824
 825 void
 826 finish_pam(void)
 827 {
 828         sshpam_cleanup();
 829 }
 830
 831 u_int
 832 do_pam_account(void)
 833 {
 834         debug("%s: called", __func__);
 835         if (sshpam_account_status != -1)
 836                 return (sshpam_account_status);
 837
 838         sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
 839         debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
 840             pam_strerror(sshpam_handle, sshpam_err));
 841
 842         if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
 843                 sshpam_account_status = 0;
 844                 return (sshpam_account_status);
 845         }
 846
 847         if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
 848                 sshpam_password_change_required(1);
 849
 850         sshpam_account_status = 1;
 851         return (sshpam_account_status);
 852 }
 853
 854 void
 855 do_pam_set_tty(const char *tty)
 856 {
 857         if (tty != NULL) {
 858                 debug("PAM: setting PAM_TTY to \"%s\"", tty);
 859                 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
 860                 if (sshpam_err != PAM_SUCCESS)
 861                         fatal("PAM: failed to set PAM_TTY: %s",
 862                             pam_strerror(sshpam_handle, sshpam_err));
 863         }
 864 }
 865
 866 void
 867 do_pam_setcred(int init)
 868 {
 869         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 870             (const void *)&store_conv);
 871         if (sshpam_err != PAM_SUCCESS)
 872                 fatal("PAM: failed to set PAM_CONV: %s",
 873                     pam_strerror(sshpam_handle, sshpam_err));
 874         if (init) {
 875                 debug("PAM: establishing credentials");
 876                 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
 877         } else {
 878                 debug("PAM: reinitializing credentials");
 879                 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
 880         }
 881         if (sshpam_err == PAM_SUCCESS) {
 882                 sshpam_cred_established = 1;
 883                 return;
 884         }
 885         if (sshpam_authenticated)
 886                 fatal("PAM: pam_setcred(): %s",
 887                     pam_strerror(sshpam_handle, sshpam_err));
 888         else
 889                 debug("PAM: pam_setcred(): %s",
 890                     pam_strerror(sshpam_handle, sshpam_err));
 891 }
 892
 893 static int
 894 sshpam_tty_conv(int n, struct pam_message **msg,
 895     struct pam_response **resp, void *data)
 896 {
 897         char input[PAM_MAX_MSG_SIZE];
 898         struct pam_response *reply;
 899         int i;
 900
 901         debug3("PAM: %s called with %d messages", __func__, n);
 902
 903         *resp = NULL;
 904
 905         if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
 906                 return (PAM_CONV_ERR);
 907
 908         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 909                 return (PAM_CONV_ERR);
 910         memset(reply, 0, n * sizeof(*reply));
 911
 912         for (i = 0; i < n; ++i) {
 913                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 914                 case PAM_PROMPT_ECHO_OFF:
 915                         reply[i].resp =
 916                             read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
 917                             RP_ALLOW_STDIN);
 918                         reply[i].resp_retcode = PAM_SUCCESS;
 919                         break;
 920                 case PAM_PROMPT_ECHO_ON:
 921                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 922                         fgets(input, sizeof input, stdin);
 923                         if ((reply[i].resp = strdup(input)) == NULL)
 924                                 goto fail;
 925                         reply[i].resp_retcode = PAM_SUCCESS;
 926                         break;
 927                 case PAM_ERROR_MSG:
 928                 case PAM_TEXT_INFO:
 929                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 930                         reply[i].resp_retcode = PAM_SUCCESS;
 931                         break;
 932                 default:
 933                         goto fail;
 934                 }
 935         }
 936         *resp = reply;
 937         return (PAM_SUCCESS);
 938
 939  fail:
 940         for(i = 0; i < n; i++) {
 941                 if (reply[i].resp != NULL)
 942                         xfree(reply[i].resp);
 943         }
 944         xfree(reply);
 945         return (PAM_CONV_ERR);
 946 }
 947
 948 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
 949
 950 /*
 951  * XXX this should be done in the authentication phase, but ssh1 doesn't
 952  * support that
 953  */
 954 void
 955 do_pam_chauthtok(void)
 956 {
 957         if (use_privsep)
 958                 fatal("Password expired (unable to change with privsep)");
 959         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 960             (const void *)&tty_conv);
 961         if (sshpam_err != PAM_SUCCESS)
 962                 fatal("PAM: failed to set PAM_CONV: %s",
 963                     pam_strerror(sshpam_handle, sshpam_err));
 964         debug("PAM: changing password");
 965         sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
 966         if (sshpam_err != PAM_SUCCESS)
 967                 fatal("PAM: pam_chauthtok(): %s",
 968                     pam_strerror(sshpam_handle, sshpam_err));
 969 }
 970
 971 void
 972 do_pam_session(void)
 973 {
 974         debug3("PAM: opening session");
 975         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 976             (const void *)&store_conv);
 977         if (sshpam_err != PAM_SUCCESS)
 978                 fatal("PAM: failed to set PAM_CONV: %s",
 979                     pam_strerror(sshpam_handle, sshpam_err));
 980         sshpam_err = pam_open_session(sshpam_handle, 0);
 981         if (sshpam_err == PAM_SUCCESS)
 982                 sshpam_session_open = 1;
 983         else {
 984                 sshpam_session_open = 0;
 985                 disable_forwarding();
 986                 error("PAM: pam_open_session(): %s",
 987                     pam_strerror(sshpam_handle, sshpam_err));
 988         }
 989
 990 }
 991
 992 int
 993 is_pam_session_open(void)
 994 {
 995         return sshpam_session_open;
 996 }
 997
 998 /*
 999  * Set a PAM environment string. We need to do this so that the session
1000  * modules can handle things like Kerberos/GSI credentials that appear
1001  * during the ssh authentication process.
1002  */
1003 int
1004 do_pam_putenv(char *name, char *value)
1005 {
1006         int ret = 1;
1007 #ifdef HAVE_PAM_PUTENV
1008         char *compound;
1009         size_t len;
1010
1011         len = strlen(name) + strlen(value) + 2;
1012         compound = xmalloc(len);
1013
1014         snprintf(compound, len, "%s=%s", name, value);
1015         ret = pam_putenv(sshpam_handle, compound);
1016         xfree(compound);
1017 #endif
1018
1019         return (ret);
1020 }
1021
1022 char **
1023 fetch_pam_child_environment(void)
1024 {
1025         return sshpam_env;
1026 }
1027
1028 char **
1029 fetch_pam_environment(void)
1030 {
1031         return (pam_getenvlist(sshpam_handle));
1032 }
1033
1034 void
1035 free_pam_environment(char **env)
1036 {
1037         char **envp;
1038
1039         if (env == NULL)
1040                 return;
1041
1042         for (envp = env; *envp; envp++)
1043                 xfree(*envp);
1044         xfree(env);
1045 }
1046
1047 /*
1048  * "Blind" conversation function for password authentication.  Assumes that
1049  * echo-off prompts are for the password and stores messages for later
1050  * display.
1051  */
1052 static int
1053 sshpam_passwd_conv(int n, struct pam_message **msg,
1054     struct pam_response **resp, void *data)
1055 {
1056         struct pam_response *reply;
1057         int i;
1058         size_t len;
1059
1060         debug3("PAM: %s called with %d messages", __func__, n);
1061
1062         *resp = NULL;
1063
1064         if (n <= 0 || n > PAM_MAX_NUM_MSG)
1065                 return (PAM_CONV_ERR);
1066
1067         if ((reply = malloc(n * sizeof(*reply))) == NULL)
1068                 return (PAM_CONV_ERR);
1069         memset(reply, 0, n * sizeof(*reply));
1070
1071         for (i = 0; i < n; ++i) {
1072                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1073                 case PAM_PROMPT_ECHO_OFF:
1074                         if (sshpam_password == NULL)
1075                                 goto fail;
1076                         if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1077                                 goto fail;
1078                         reply[i].resp_retcode = PAM_SUCCESS;
1079                         break;
1080                 case PAM_ERROR_MSG:
1081                 case PAM_TEXT_INFO:
1082                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1083                         if (len > 0) {
1084                                 buffer_append(&loginmsg,
1085                                     PAM_MSG_MEMBER(msg, i, msg), len);
1086                                 buffer_append(&loginmsg, "\n", 1);
1087                         }
1088                         if ((reply[i].resp = strdup("")) == NULL)
1089                                 goto fail;
1090                         reply[i].resp_retcode = PAM_SUCCESS;
1091                         break;
1092                 default:
1093                         goto fail;
1094                 }
1095         }
1096         *resp = reply;
1097         return (PAM_SUCCESS);
1098
1099  fail:
1100         for(i = 0; i < n; i++) {
1101                 if (reply[i].resp != NULL)
1102                         xfree(reply[i].resp);
1103         }
1104         xfree(reply);
1105         return (PAM_CONV_ERR);
1106 }
1107
1108 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1109
1110 /*
1111  * Attempt password authentication via PAM
1112  */
1113 int
1114 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1115 {
1116         int flags = (options.permit_empty_passwd == 0 ?
1117             PAM_DISALLOW_NULL_AUTHTOK : 0);
1118
1119         if (!options.use_pam || sshpam_handle == NULL)
1120                 fatal("PAM: %s called when PAM disabled or failed to "
1121                     "initialise.", __func__);
1122
1123         sshpam_password = password;
1124         sshpam_authctxt = authctxt;
1125
1126         /*
1127          * If the user logging in is invalid, or is root but is not permitted
1128          * by PermitRootLogin, use an invalid password to prevent leaking
1129          * information via timing (eg if the PAM config has a delay on fail).
1130          */
1131         if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1132              options.permit_root_login != PERMIT_YES))
1133                 sshpam_password = badpw;
1134
1135         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1136             (const void *)&passwd_conv);
1137         if (sshpam_err != PAM_SUCCESS)
1138                 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1139                     pam_strerror(sshpam_handle, sshpam_err));
1140
1141         sshpam_err = pam_authenticate(sshpam_handle, flags);
1142         sshpam_password = NULL;
1143         if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1144                 debug("PAM: password authentication accepted for %.100s",
1145                     authctxt->user);
1146                return 1;
1147         } else {
1148                 debug("PAM: password authentication failed for %.100s: %s",
1149                     authctxt->valid ? authctxt->user : "an illegal user",
1150                     pam_strerror(sshpam_handle, sshpam_err));
1151                 return 0;
1152         }
1153 }
1154 #endif /* USE_PAM */