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 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */
  60 #ifdef PAM_SUN_CODEBASE
  61 # define sshpam_const           /* Solaris, HP-UX, AIX */
  62 #else
  63 # define sshpam_const   const   /* LinuxPAM, OpenPAM */
  64 #endif
  65
  66 #include "auth.h"
  67 #include "auth-pam.h"
  68 #include "buffer.h"
  69 #include "bufaux.h"
  70 #include "canohost.h"
  71 #include "log.h"
  72 #include "monitor_wrap.h"
  73 #include "msg.h"
  74 #include "packet.h"
  75 #include "misc.h"
  76 #include "servconf.h"
  77 #include "ssh2.h"
  78 #include "xmalloc.h"
  79 #include "auth-options.h"
  80
  81 extern ServerOptions options;
  82 extern Buffer loginmsg;
  83 extern int compat20;
  84 extern u_int utmp_len;
  85
  86 /* so we don't silently change behaviour */
  87 #ifdef USE_POSIX_THREADS
  88 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
  89 #endif
  90
  91 /*
  92  * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
  93  * and generally a bad idea.  Use at own risk and do not expect support if
  94  * this breaks.
  95  */
  96 #ifdef UNSUPPORTED_POSIX_THREADS_HACK
  97 #include <pthread.h>
  98 /*
  99  * Avoid namespace clash when *not* using pthreads for systems *with*
 100  * pthreads, which unconditionally define pthread_t via sys/types.h
 101  * (e.g. Linux)
 102  */
 103 typedef pthread_t sp_pthread_t;
 104 #else
 105 typedef pid_t sp_pthread_t;
 106 #endif
 107
 108 struct pam_ctxt {
 109         sp_pthread_t     pam_thread;
 110         int              pam_psock;
 111         int              pam_csock;
 112         int              pam_done;
 113 };
 114
 115 static void sshpam_free_ctx(void *);
 116 static struct pam_ctxt *cleanup_ctxt;
 117
 118 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 119 /*
 120  * Simulate threads with processes.
 121  */
 122
 123 static int sshpam_thread_status = -1;
 124 static mysig_t sshpam_oldsig;
 125
 126 static void
 127 sshpam_sigchld_handler(int sig)
 128 {
 129         signal(SIGCHLD, SIG_DFL);
 130         if (cleanup_ctxt == NULL)
 131                 return; /* handler called after PAM cleanup, shouldn't happen */
 132         if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
 133              <= 0) {
 134                 /* PAM thread has not exitted, privsep slave must have */
 135                 kill(cleanup_ctxt->pam_thread, SIGTERM);
 136                 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0)
 137                     <= 0)
 138                         return; /* could not wait */
 139         }
 140         if (WIFSIGNALED(sshpam_thread_status) &&
 141             WTERMSIG(sshpam_thread_status) == SIGTERM)
 142                 return; /* terminated by pthread_cancel */
 143         if (!WIFEXITED(sshpam_thread_status))
 144                 fatal("PAM: authentication thread exited unexpectedly");
 145         if (WEXITSTATUS(sshpam_thread_status) != 0)
 146                 fatal("PAM: authentication thread exited uncleanly");
 147 }
 148
 149 static void
 150 pthread_exit(void *value __unused)
 151 {
 152         _exit(0);
 153 }
 154
 155 static int
 156 pthread_create(sp_pthread_t *thread, const void *attr __unused,
 157     void *(*thread_start)(void *), void *arg)
 158 {
 159         pid_t pid;
 160
 161         sshpam_thread_status = -1;
 162         switch ((pid = fork())) {
 163         case -1:
 164                 error("fork(): %s", strerror(errno));
 165                 return (-1);
 166         case 0:
 167                 thread_start(arg);
 168                 _exit(1);
 169         default:
 170                 *thread = pid;
 171                 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
 172                 return (0);
 173         }
 174 }
 175
 176 static int
 177 pthread_cancel(sp_pthread_t thread)
 178 {
 179         signal(SIGCHLD, sshpam_oldsig);
 180         return (kill(thread, SIGTERM));
 181 }
 182
 183 static int
 184 pthread_join(sp_pthread_t thread, void **value __unused)
 185 {
 186         int status;
 187
 188         if (sshpam_thread_status != -1)
 189                 return (sshpam_thread_status);
 190         signal(SIGCHLD, sshpam_oldsig);
 191         waitpid(thread, &status, 0);
 192         return (status);
 193 }
 194 #endif
 195
 196
 197 static pam_handle_t *sshpam_handle = NULL;
 198 static int sshpam_err = 0;
 199 static int sshpam_authenticated = 0;
 200 static int sshpam_session_open = 0;
 201 static int sshpam_cred_established = 0;
 202 static int sshpam_account_status = -1;
 203 static char **sshpam_env = NULL;
 204 static Authctxt *sshpam_authctxt = NULL;
 205 static const char *sshpam_password = NULL;
 206 static char badpw[] = "\b\n\r\177INCORRECT";
 207
 208 /* Some PAM implementations don't implement this */
 209 #ifndef HAVE_PAM_GETENVLIST
 210 static char **
 211 pam_getenvlist(pam_handle_t *pamh)
 212 {
 213         /*
 214          * XXX - If necessary, we can still support envrionment passing
 215          * for platforms without pam_getenvlist by searching for known
 216          * env vars (e.g. KRB5CCNAME) from the PAM environment.
 217          */
 218          return NULL;
 219 }
 220 #endif
 221
 222 /*
 223  * Some platforms, notably Solaris, do not enforce password complexity
 224  * rules during pam_chauthtok() if the real uid of the calling process
 225  * is 0, on the assumption that it's being called by "passwd" run by root.
 226  * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
 227  * the right thing.
 228  */
 229 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
 230 static int
 231 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
 232 {
 233         int result;
 234
 235         if (sshpam_authctxt == NULL)
 236                 fatal("PAM: sshpam_authctxt not initialized");
 237         if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
 238                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 239         result = pam_chauthtok(pamh, flags);
 240         if (setreuid(0, -1) == -1)
 241                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 242         return result;
 243 }
 244 # define pam_chauthtok(a,b)     (sshpam_chauthtok_ruid((a), (b)))
 245 #endif
 246
 247 void
 248 sshpam_password_change_required(int reqd)
 249 {
 250         debug3("%s %d", __func__, reqd);
 251         if (sshpam_authctxt == NULL)
 252                 fatal("%s: PAM authctxt not initialized", __func__);
 253         sshpam_authctxt->force_pwchange = reqd;
 254         if (reqd) {
 255                 no_port_forwarding_flag |= 2;
 256                 no_agent_forwarding_flag |= 2;
 257                 no_x11_forwarding_flag |= 2;
 258         } else {
 259                 no_port_forwarding_flag &= ~2;
 260                 no_agent_forwarding_flag &= ~2;
 261                 no_x11_forwarding_flag &= ~2;
 262         }
 263 }
 264
 265 /* Import regular and PAM environment from subprocess */
 266 static void
 267 import_environments(Buffer *b)
 268 {
 269         char *env;
 270         u_int i, num_env;
 271         int err;
 272
 273         debug3("PAM: %s entering", __func__);
 274
 275 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 276         /* Import variables set by do_pam_account */
 277         sshpam_account_status = buffer_get_int(b);
 278         sshpam_password_change_required(buffer_get_int(b));
 279
 280         /* Import environment from subprocess */
 281         num_env = buffer_get_int(b);
 282         sshpam_env = xmalloc((num_env + 1) * sizeof(*sshpam_env));
 283         debug3("PAM: num env strings %d", num_env);
 284         for(i = 0; i < num_env; i++)
 285                 sshpam_env[i] = buffer_get_string(b, NULL);
 286
 287         sshpam_env[num_env] = NULL;
 288
 289         /* Import PAM environment from subprocess */
 290         num_env = buffer_get_int(b);
 291         debug("PAM: num PAM env strings %d", num_env);
 292         for(i = 0; i < num_env; i++) {
 293                 env = buffer_get_string(b, NULL);
 294
 295 #ifdef HAVE_PAM_PUTENV
 296                 /* Errors are not fatal here */
 297                 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
 298                         error("PAM: pam_putenv: %s",
 299                             pam_strerror(sshpam_handle, sshpam_err));
 300                 }
 301 #endif
 302         }
 303 #endif
 304 }
 305
 306 /*
 307  * Conversation function for authentication thread.
 308  */
 309 static int
 310 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
 311     struct pam_response **resp, void *data)
 312 {
 313         Buffer buffer;
 314         struct pam_ctxt *ctxt;
 315         struct pam_response *reply;
 316         int i;
 317
 318         debug3("PAM: %s entering, %d messages", __func__, n);
 319         *resp = NULL;
 320
 321         if (data == NULL) {
 322                 error("PAM: conversation function passed a null context");
 323                 return (PAM_CONV_ERR);
 324         }
 325         ctxt = data;
 326         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 327                 return (PAM_CONV_ERR);
 328
 329         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 330                 return (PAM_CONV_ERR);
 331         memset(reply, 0, n * sizeof(*reply));
 332
 333         buffer_init(&buffer);
 334         for (i = 0; i < n; ++i) {
 335                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 336                 case PAM_PROMPT_ECHO_OFF:
 337                         buffer_put_cstring(&buffer,
 338                             PAM_MSG_MEMBER(msg, i, msg));
 339                         if (ssh_msg_send(ctxt->pam_csock,
 340                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 341                                 goto fail;
 342                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 343                                 goto fail;
 344                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 345                                 goto fail;
 346                         reply[i].resp = buffer_get_string(&buffer, NULL);
 347                         break;
 348                 case PAM_PROMPT_ECHO_ON:
 349                         buffer_put_cstring(&buffer,
 350                             PAM_MSG_MEMBER(msg, i, msg));
 351                         if (ssh_msg_send(ctxt->pam_csock,
 352                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 353                                 goto fail;
 354                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 355                                 goto fail;
 356                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 357                                 goto fail;
 358                         reply[i].resp = buffer_get_string(&buffer, NULL);
 359                         break;
 360                 case PAM_ERROR_MSG:
 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                 case PAM_TEXT_INFO:
 368                         buffer_put_cstring(&buffer,
 369                             PAM_MSG_MEMBER(msg, i, msg));
 370                         if (ssh_msg_send(ctxt->pam_csock,
 371                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 372                                 goto fail;
 373                         break;
 374                 default:
 375                         goto fail;
 376                 }
 377                 buffer_clear(&buffer);
 378         }
 379         buffer_free(&buffer);
 380         *resp = reply;
 381         return (PAM_SUCCESS);
 382
 383  fail:
 384         for(i = 0; i < n; i++) {
 385                 if (reply[i].resp != NULL)
 386                         xfree(reply[i].resp);
 387         }
 388         xfree(reply);
 389         buffer_free(&buffer);
 390         return (PAM_CONV_ERR);
 391 }
 392
 393 /*
 394  * Authentication thread.
 395  */
 396 static void *
 397 sshpam_thread(void *ctxtp)
 398 {
 399         struct pam_ctxt *ctxt = ctxtp;
 400         Buffer buffer;
 401         struct pam_conv sshpam_conv;
 402         int flags = (options.permit_empty_passwd == 0 ?
 403             PAM_DISALLOW_NULL_AUTHTOK : 0);
 404 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 405         extern char **environ;
 406         char **env_from_pam;
 407         u_int i;
 408         const char *pam_user;
 409         const char **ptr_pam_user = &pam_user;
 410
 411         pam_get_item(sshpam_handle, PAM_USER,
 412             (sshpam_const void **)ptr_pam_user);
 413         environ[0] = NULL;
 414
 415         if (sshpam_authctxt != NULL) {
 416                 setproctitle("%s [pam]",
 417                     sshpam_authctxt->valid ? pam_user : "unknown");
 418         }
 419 #endif
 420
 421         sshpam_conv.conv = sshpam_thread_conv;
 422         sshpam_conv.appdata_ptr = ctxt;
 423
 424         if (sshpam_authctxt == NULL)
 425                 fatal("%s: PAM authctxt not initialized", __func__);
 426
 427         buffer_init(&buffer);
 428         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 429             (const void *)&sshpam_conv);
 430         if (sshpam_err != PAM_SUCCESS)
 431                 goto auth_fail;
 432         sshpam_err = pam_authenticate(sshpam_handle, flags);
 433         if (sshpam_err != PAM_SUCCESS)
 434                 goto auth_fail;
 435
 436         if (compat20) {
 437                 if (!do_pam_account())
 438                         goto auth_fail;
 439                 if (sshpam_authctxt->force_pwchange) {
 440                         sshpam_err = pam_chauthtok(sshpam_handle,
 441                             PAM_CHANGE_EXPIRED_AUTHTOK);
 442                         if (sshpam_err != PAM_SUCCESS)
 443                                 goto auth_fail;
 444                         sshpam_password_change_required(0);
 445                 }
 446         }
 447
 448         buffer_put_cstring(&buffer, "OK");
 449
 450 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 451         /* Export variables set by do_pam_account */
 452         buffer_put_int(&buffer, sshpam_account_status);
 453         buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);
 454
 455         /* Export any environment strings set in child */
 456         for(i = 0; environ[i] != NULL; i++)
 457                 ; /* Count */
 458         buffer_put_int(&buffer, i);
 459         for(i = 0; environ[i] != NULL; i++)
 460                 buffer_put_cstring(&buffer, environ[i]);
 461
 462         /* Export any environment strings set by PAM in child */
 463         env_from_pam = pam_getenvlist(sshpam_handle);
 464         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 465                 ; /* Count */
 466         buffer_put_int(&buffer, i);
 467         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 468                 buffer_put_cstring(&buffer, env_from_pam[i]);
 469 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */
 470
 471         /* XXX - can't do much about an error here */
 472         ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
 473         buffer_free(&buffer);
 474         pthread_exit(NULL);
 475
 476  auth_fail:
 477         buffer_put_cstring(&buffer,
 478             pam_strerror(sshpam_handle, sshpam_err));
 479         /* XXX - can't do much about an error here */
 480         ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
 481         buffer_free(&buffer);
 482         pthread_exit(NULL);
 483
 484         return (NULL); /* Avoid warning for non-pthread case */
 485 }
 486
 487 void
 488 sshpam_thread_cleanup(void)
 489 {
 490         struct pam_ctxt *ctxt = cleanup_ctxt;
 491
 492         debug3("PAM: %s entering", __func__);
 493         if (ctxt != NULL && ctxt->pam_thread != 0) {
 494                 pthread_cancel(ctxt->pam_thread);
 495                 pthread_join(ctxt->pam_thread, NULL);
 496                 close(ctxt->pam_psock);
 497                 close(ctxt->pam_csock);
 498                 memset(ctxt, 0, sizeof(*ctxt));
 499                 cleanup_ctxt = NULL;
 500         }
 501 }
 502
 503 static int
 504 sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
 505     struct pam_response **resp, void *data)
 506 {
 507         debug3("PAM: %s entering, %d messages", __func__, n);
 508         return (PAM_CONV_ERR);
 509 }
 510
 511 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
 512
 513 static int
 514 sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
 515     struct pam_response **resp, void *data)
 516 {
 517         struct pam_response *reply;
 518         int i;
 519         size_t len;
 520
 521         debug3("PAM: %s called with %d messages", __func__, n);
 522         *resp = NULL;
 523
 524         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 525                 return (PAM_CONV_ERR);
 526
 527         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 528                 return (PAM_CONV_ERR);
 529         memset(reply, 0, n * sizeof(*reply));
 530
 531         for (i = 0; i < n; ++i) {
 532                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 533                 case PAM_ERROR_MSG:
 534                 case PAM_TEXT_INFO:
 535                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
 536                         buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
 537                         buffer_append(&loginmsg, "\n", 1 );
 538                         reply[i].resp_retcode = PAM_SUCCESS;
 539                         break;
 540                 default:
 541                         goto fail;
 542                 }
 543         }
 544         *resp = reply;
 545         return (PAM_SUCCESS);
 546
 547  fail:
 548         for(i = 0; i < n; i++) {
 549                 if (reply[i].resp != NULL)
 550                         xfree(reply[i].resp);
 551         }
 552         xfree(reply);
 553         return (PAM_CONV_ERR);
 554 }
 555
 556 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
 557
 558 void
 559 sshpam_cleanup(void)
 560 {
 561         debug("PAM: cleanup");
 562         if (sshpam_handle == NULL)
 563                 return;
 564         pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 565         if (sshpam_cred_established) {
 566                 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
 567                 sshpam_cred_established = 0;
 568         }
 569         if (sshpam_session_open) {
 570                 pam_close_session(sshpam_handle, PAM_SILENT);
 571                 sshpam_session_open = 0;
 572         }
 573         sshpam_authenticated = 0;
 574         pam_end(sshpam_handle, sshpam_err);
 575         sshpam_handle = NULL;
 576 }
 577
 578 static int
 579 sshpam_init(Authctxt *authctxt)
 580 {
 581         extern char *__progname;
 582         const char *pam_rhost, *pam_user, *user = authctxt->user;
 583         const char **ptr_pam_user = &pam_user;
 584
 585         if (sshpam_handle != NULL) {
 586                 /* We already have a PAM context; check if the user matches */
 587                 sshpam_err = pam_get_item(sshpam_handle,
 588                     PAM_USER, (sshpam_const void **)ptr_pam_user);
 589                 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
 590                         return (0);
 591                 pam_end(sshpam_handle, sshpam_err);
 592                 sshpam_handle = NULL;
 593         }
 594         debug("PAM: initializing for \"%s\"", user);
 595         sshpam_err =
 596             pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
 597         sshpam_authctxt = authctxt;
 598
 599         if (sshpam_err != PAM_SUCCESS) {
 600                 pam_end(sshpam_handle, sshpam_err);
 601                 sshpam_handle = NULL;
 602                 return (-1);
 603         }
 604         pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
 605         debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
 606         sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
 607         if (sshpam_err != PAM_SUCCESS) {
 608                 pam_end(sshpam_handle, sshpam_err);
 609                 sshpam_handle = NULL;
 610                 return (-1);
 611         }
 612 #ifdef PAM_TTY_KLUDGE
 613         /*
 614          * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
 615          * sshd doesn't set the tty until too late in the auth process and
 616          * may not even set one (for tty-less connections)
 617          */
 618         debug("PAM: setting PAM_TTY to \"ssh\"");
 619         sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
 620         if (sshpam_err != PAM_SUCCESS) {
 621                 pam_end(sshpam_handle, sshpam_err);
 622                 sshpam_handle = NULL;
 623                 return (-1);
 624         }
 625 #endif
 626         return (0);
 627 }
 628
 629 static void *
 630 sshpam_init_ctx(Authctxt *authctxt)
 631 {
 632         struct pam_ctxt *ctxt;
 633         int socks[2];
 634
 635         debug3("PAM: %s entering", __func__);
 636         /* Refuse to start if we don't have PAM enabled */
 637         if (!options.use_pam)
 638                 return NULL;
 639
 640         /* Initialize PAM */
 641         if (sshpam_init(authctxt) == -1) {
 642                 error("PAM: initialization failed");
 643                 return (NULL);
 644         }
 645
 646         ctxt = xmalloc(sizeof *ctxt);
 647         memset(ctxt, 0, sizeof(*ctxt));
 648
 649         /* Start the authentication thread */
 650         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
 651                 error("PAM: failed create sockets: %s", strerror(errno));
 652                 xfree(ctxt);
 653                 return (NULL);
 654         }
 655         ctxt->pam_psock = socks[0];
 656         ctxt->pam_csock = socks[1];
 657         if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
 658                 error("PAM: failed to start authentication thread: %s",
 659                     strerror(errno));
 660                 close(socks[0]);
 661                 close(socks[1]);
 662                 xfree(ctxt);
 663                 return (NULL);
 664         }
 665         cleanup_ctxt = ctxt;
 666         return (ctxt);
 667 }
 668
 669 static int
 670 sshpam_query(void *ctx, char **name, char **info,
 671     u_int *num, char ***prompts, u_int **echo_on)
 672 {
 673         Buffer buffer;
 674         struct pam_ctxt *ctxt = ctx;
 675         size_t plen;
 676         u_char type;
 677         char *msg;
 678         size_t len, mlen;
 679
 680         debug3("PAM: %s entering", __func__);
 681         buffer_init(&buffer);
 682         *name = xstrdup("");
 683         *info = xstrdup("");
 684         *prompts = xmalloc(sizeof(char *));
 685         **prompts = NULL;
 686         plen = 0;
 687         *echo_on = xmalloc(sizeof(u_int));
 688         while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
 689                 type = buffer_get_char(&buffer);
 690                 msg = buffer_get_string(&buffer, NULL);
 691                 mlen = strlen(msg);
 692                 switch (type) {
 693                 case PAM_PROMPT_ECHO_ON:
 694                 case PAM_PROMPT_ECHO_OFF:
 695                         *num = 1;
 696                         len = plen + mlen + 1;
 697                         **prompts = xrealloc(**prompts, len);
 698                         strlcpy(**prompts + plen, msg, len - plen);
 699                         plen += mlen;
 700                         **echo_on = (type == PAM_PROMPT_ECHO_ON);
 701                         xfree(msg);
 702                         return (0);
 703                 case PAM_ERROR_MSG:
 704                 case PAM_TEXT_INFO:
 705                         /* accumulate messages */
 706                         len = plen + mlen + 2;
 707                         **prompts = xrealloc(**prompts, len);
 708                         strlcpy(**prompts + plen, msg, len - plen);
 709                         plen += mlen;
 710                         strlcat(**prompts + plen, "\n", len - plen);
 711                         plen++;
 712                         xfree(msg);
 713                         break;
 714                 case PAM_SUCCESS:
 715                 case PAM_AUTH_ERR:
 716                         if (**prompts != NULL) {
 717                                 /* drain any accumulated messages */
 718                                 debug("PAM: %s", **prompts);
 719                                 buffer_append(&loginmsg, **prompts,
 720                                     strlen(**prompts));
 721                                 xfree(**prompts);
 722                                 **prompts = NULL;
 723                         }
 724                         if (type == PAM_SUCCESS) {
 725                                 if (!sshpam_authctxt->valid ||
 726                                     (sshpam_authctxt->pw->pw_uid == 0 &&
 727                                     options.permit_root_login != PERMIT_YES))
 728                                         fatal("Internal error: PAM auth "
 729                                             "succeeded when it should have "
 730                                             "failed");
 731                                 import_environments(&buffer);
 732                                 *num = 0;
 733                                 **echo_on = 0;
 734                                 ctxt->pam_done = 1;
 735                                 xfree(msg);
 736                                 return (0);
 737                         }
 738                         error("PAM: %s for %s%.100s from %.100s", msg,
 739                             sshpam_authctxt->valid ? "" : "illegal user ",
 740                             sshpam_authctxt->user,
 741                             get_remote_name_or_ip(utmp_len, options.use_dns));
 742                         /* FALLTHROUGH */
 743                 default:
 744                         *num = 0;
 745                         **echo_on = 0;
 746                         xfree(msg);
 747                         ctxt->pam_done = -1;
 748                         return (-1);
 749                 }
 750         }
 751         return (-1);
 752 }
 753
 754 /* XXX - see also comment in auth-chall.c:verify_response */
 755 static int
 756 sshpam_respond(void *ctx, u_int num, char **resp)
 757 {
 758         Buffer buffer;
 759         struct pam_ctxt *ctxt = ctx;
 760
 761         debug2("PAM: %s entering, %d responses", __func__, num);
 762         switch (ctxt->pam_done) {
 763         case 1:
 764                 sshpam_authenticated = 1;
 765                 return (0);
 766         case 0:
 767                 break;
 768         default:
 769                 return (-1);
 770         }
 771         if (num != 1) {
 772                 error("PAM: expected one response, got %u", num);
 773                 return (-1);
 774         }
 775         buffer_init(&buffer);
 776         if (sshpam_authctxt->valid &&
 777             (sshpam_authctxt->pw->pw_uid != 0 ||
 778              options.permit_root_login == PERMIT_YES))
 779                 buffer_put_cstring(&buffer, *resp);
 780         else
 781                 buffer_put_cstring(&buffer, badpw);
 782         if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
 783                 buffer_free(&buffer);
 784                 return (-1);
 785         }
 786         buffer_free(&buffer);
 787         return (1);
 788 }
 789
 790 static void
 791 sshpam_free_ctx(void *ctxtp)
 792 {
 793         struct pam_ctxt *ctxt = ctxtp;
 794
 795         debug3("PAM: %s entering", __func__);
 796         sshpam_thread_cleanup();
 797         xfree(ctxt);
 798         /*
 799          * We don't call sshpam_cleanup() here because we may need the PAM
 800          * handle at a later stage, e.g. when setting up a session.  It's
 801          * still on the cleanup list, so pam_end() *will* be called before
 802          * the server process terminates.
 803          */
 804 }
 805
 806 KbdintDevice sshpam_device = {
 807         "pam",
 808         sshpam_init_ctx,
 809         sshpam_query,
 810         sshpam_respond,
 811         sshpam_free_ctx
 812 };
 813
 814 KbdintDevice mm_sshpam_device = {
 815         "pam",
 816         mm_sshpam_init_ctx,
 817         mm_sshpam_query,
 818         mm_sshpam_respond,
 819         mm_sshpam_free_ctx
 820 };
 821
 822 /*
 823  * This replaces auth-pam.c
 824  */
 825 void
 826 start_pam(Authctxt *authctxt)
 827 {
 828         if (!options.use_pam)
 829                 fatal("PAM: initialisation requested when UsePAM=no");
 830
 831         if (sshpam_init(authctxt) == -1)
 832                 fatal("PAM: initialisation failed");
 833 }
 834
 835 void
 836 finish_pam(void)
 837 {
 838         sshpam_cleanup();
 839 }
 840
 841 u_int
 842 do_pam_account(void)
 843 {
 844         debug("%s: called", __func__);
 845         if (sshpam_account_status != -1)
 846                 return (sshpam_account_status);
 847
 848         sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
 849         debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
 850             pam_strerror(sshpam_handle, sshpam_err));
 851
 852         if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
 853                 sshpam_account_status = 0;
 854                 return (sshpam_account_status);
 855         }
 856
 857         if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
 858                 sshpam_password_change_required(1);
 859
 860         sshpam_account_status = 1;
 861         return (sshpam_account_status);
 862 }
 863
 864 void
 865 do_pam_set_tty(const char *tty)
 866 {
 867         if (tty != NULL) {
 868                 debug("PAM: setting PAM_TTY to \"%s\"", tty);
 869                 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
 870                 if (sshpam_err != PAM_SUCCESS)
 871                         fatal("PAM: failed to set PAM_TTY: %s",
 872                             pam_strerror(sshpam_handle, sshpam_err));
 873         }
 874 }
 875
 876 void
 877 do_pam_setcred(int init)
 878 {
 879         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 880             (const void *)&store_conv);
 881         if (sshpam_err != PAM_SUCCESS)
 882                 fatal("PAM: failed to set PAM_CONV: %s",
 883                     pam_strerror(sshpam_handle, sshpam_err));
 884         if (init) {
 885                 debug("PAM: establishing credentials");
 886                 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
 887         } else {
 888                 debug("PAM: reinitializing credentials");
 889                 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
 890         }
 891         if (sshpam_err == PAM_SUCCESS) {
 892                 sshpam_cred_established = 1;
 893                 return;
 894         }
 895         if (sshpam_authenticated)
 896                 fatal("PAM: pam_setcred(): %s",
 897                     pam_strerror(sshpam_handle, sshpam_err));
 898         else
 899                 debug("PAM: pam_setcred(): %s",
 900                     pam_strerror(sshpam_handle, sshpam_err));
 901 }
 902
 903 static int
 904 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
 905     struct pam_response **resp, void *data)
 906 {
 907         char input[PAM_MAX_MSG_SIZE];
 908         struct pam_response *reply;
 909         int i;
 910
 911         debug3("PAM: %s called with %d messages", __func__, n);
 912
 913         *resp = NULL;
 914
 915         if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
 916                 return (PAM_CONV_ERR);
 917
 918         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 919                 return (PAM_CONV_ERR);
 920         memset(reply, 0, n * sizeof(*reply));
 921
 922         for (i = 0; i < n; ++i) {
 923                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 924                 case PAM_PROMPT_ECHO_OFF:
 925                         reply[i].resp =
 926                             read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
 927                             RP_ALLOW_STDIN);
 928                         reply[i].resp_retcode = PAM_SUCCESS;
 929                         break;
 930                 case PAM_PROMPT_ECHO_ON:
 931                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 932                         fgets(input, sizeof input, stdin);
 933                         if ((reply[i].resp = strdup(input)) == NULL)
 934                                 goto fail;
 935                         reply[i].resp_retcode = PAM_SUCCESS;
 936                         break;
 937                 case PAM_ERROR_MSG:
 938                 case PAM_TEXT_INFO:
 939                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 940                         reply[i].resp_retcode = PAM_SUCCESS;
 941                         break;
 942                 default:
 943                         goto fail;
 944                 }
 945         }
 946         *resp = reply;
 947         return (PAM_SUCCESS);
 948
 949  fail:
 950         for(i = 0; i < n; i++) {
 951                 if (reply[i].resp != NULL)
 952                         xfree(reply[i].resp);
 953         }
 954         xfree(reply);
 955         return (PAM_CONV_ERR);
 956 }
 957
 958 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
 959
 960 /*
 961  * XXX this should be done in the authentication phase, but ssh1 doesn't
 962  * support that
 963  */
 964 void
 965 do_pam_chauthtok(void)
 966 {
 967         if (use_privsep)
 968                 fatal("Password expired (unable to change with privsep)");
 969         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 970             (const void *)&tty_conv);
 971         if (sshpam_err != PAM_SUCCESS)
 972                 fatal("PAM: failed to set PAM_CONV: %s",
 973                     pam_strerror(sshpam_handle, sshpam_err));
 974         debug("PAM: changing password");
 975         sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
 976         if (sshpam_err != PAM_SUCCESS)
 977                 fatal("PAM: pam_chauthtok(): %s",
 978                     pam_strerror(sshpam_handle, sshpam_err));
 979 }
 980
 981 void
 982 do_pam_session(void)
 983 {
 984         debug3("PAM: opening session");
 985         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 986             (const void *)&store_conv);
 987         if (sshpam_err != PAM_SUCCESS)
 988                 fatal("PAM: failed to set PAM_CONV: %s",
 989                     pam_strerror(sshpam_handle, sshpam_err));
 990         sshpam_err = pam_open_session(sshpam_handle, 0);
 991         if (sshpam_err == PAM_SUCCESS)
 992                 sshpam_session_open = 1;
 993         else {
 994                 sshpam_session_open = 0;
 995                 disable_forwarding();
 996                 error("PAM: pam_open_session(): %s",
 997                     pam_strerror(sshpam_handle, sshpam_err));
 998         }
 999
1000 }
1001
1002 int
1003 is_pam_session_open(void)
1004 {
1005         return sshpam_session_open;
1006 }
1007
1008 /*
1009  * Set a PAM environment string. We need to do this so that the session
1010  * modules can handle things like Kerberos/GSI credentials that appear
1011  * during the ssh authentication process.
1012  */
1013 int
1014 do_pam_putenv(char *name, char *value)
1015 {
1016         int ret = 1;
1017 #ifdef HAVE_PAM_PUTENV
1018         char *compound;
1019         size_t len;
1020
1021         len = strlen(name) + strlen(value) + 2;
1022         compound = xmalloc(len);
1023
1024         snprintf(compound, len, "%s=%s", name, value);
1025         ret = pam_putenv(sshpam_handle, compound);
1026         xfree(compound);
1027 #endif
1028
1029         return (ret);
1030 }
1031
1032 char **
1033 fetch_pam_child_environment(void)
1034 {
1035         return sshpam_env;
1036 }
1037
1038 char **
1039 fetch_pam_environment(void)
1040 {
1041         return (pam_getenvlist(sshpam_handle));
1042 }
1043
1044 void
1045 free_pam_environment(char **env)
1046 {
1047         char **envp;
1048
1049         if (env == NULL)
1050                 return;
1051
1052         for (envp = env; *envp; envp++)
1053                 xfree(*envp);
1054         xfree(env);
1055 }
1056
1057 /*
1058  * "Blind" conversation function for password authentication.  Assumes that
1059  * echo-off prompts are for the password and stores messages for later
1060  * display.
1061  */
1062 static int
1063 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1064     struct pam_response **resp, void *data)
1065 {
1066         struct pam_response *reply;
1067         int i;
1068         size_t len;
1069
1070         debug3("PAM: %s called with %d messages", __func__, n);
1071
1072         *resp = NULL;
1073
1074         if (n <= 0 || n > PAM_MAX_NUM_MSG)
1075                 return (PAM_CONV_ERR);
1076
1077         if ((reply = malloc(n * sizeof(*reply))) == NULL)
1078                 return (PAM_CONV_ERR);
1079         memset(reply, 0, n * sizeof(*reply));
1080
1081         for (i = 0; i < n; ++i) {
1082                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1083                 case PAM_PROMPT_ECHO_OFF:
1084                         if (sshpam_password == NULL)
1085                                 goto fail;
1086                         if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1087                                 goto fail;
1088                         reply[i].resp_retcode = PAM_SUCCESS;
1089                         break;
1090                 case PAM_ERROR_MSG:
1091                 case PAM_TEXT_INFO:
1092                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1093                         if (len > 0) {
1094                                 buffer_append(&loginmsg,
1095                                     PAM_MSG_MEMBER(msg, i, msg), len);
1096                                 buffer_append(&loginmsg, "\n", 1);
1097                         }
1098                         if ((reply[i].resp = strdup("")) == NULL)
1099                                 goto fail;
1100                         reply[i].resp_retcode = PAM_SUCCESS;
1101                         break;
1102                 default:
1103                         goto fail;
1104                 }
1105         }
1106         *resp = reply;
1107         return (PAM_SUCCESS);
1108
1109  fail:
1110         for(i = 0; i < n; i++) {
1111                 if (reply[i].resp != NULL)
1112                         xfree(reply[i].resp);
1113         }
1114         xfree(reply);
1115         return (PAM_CONV_ERR);
1116 }
1117
1118 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1119
1120 /*
1121  * Attempt password authentication via PAM
1122  */
1123 int
1124 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1125 {
1126         int flags = (options.permit_empty_passwd == 0 ?
1127             PAM_DISALLOW_NULL_AUTHTOK : 0);
1128
1129         if (!options.use_pam || sshpam_handle == NULL)
1130                 fatal("PAM: %s called when PAM disabled or failed to "
1131                     "initialise.", __func__);
1132
1133         sshpam_password = password;
1134         sshpam_authctxt = authctxt;
1135
1136         /*
1137          * If the user logging in is invalid, or is root but is not permitted
1138          * by PermitRootLogin, use an invalid password to prevent leaking
1139          * information via timing (eg if the PAM config has a delay on fail).
1140          */
1141         if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1142              options.permit_root_login != PERMIT_YES))
1143                 sshpam_password = badpw;
1144
1145         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1146             (const void *)&passwd_conv);
1147         if (sshpam_err != PAM_SUCCESS)
1148                 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1149                     pam_strerror(sshpam_handle, sshpam_err));
1150
1151         sshpam_err = pam_authenticate(sshpam_handle, flags);
1152         sshpam_password = NULL;
1153         if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1154                 debug("PAM: password authentication accepted for %.100s",
1155                     authctxt->user);
1156                return 1;
1157         } else {
1158                 debug("PAM: password authentication failed for %.100s: %s",
1159                     authctxt->valid ? authctxt->user : "an illegal user",
1160                     pam_strerror(sshpam_handle, sshpam_err));
1161                 return 0;
1162         }
1163 }
1164 #endif /* USE_PAM */