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
  51 #include <sys/types.h>
  52 #include <sys/stat.h>
  53 #include <sys/wait.h>
  54
  55 #include <errno.h>
  56 #include <signal.h>
  57
  58 #ifdef USE_PAM
  59 #if defined(HAVE_SECURITY_PAM_APPL_H)
  60 #include <security/pam_appl.h>
  61 #elif defined (HAVE_PAM_PAM_APPL_H)
  62 #include <pam/pam_appl.h>
  63 #endif
  64
  65 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */
  66 #ifdef PAM_SUN_CODEBASE
  67 # define sshpam_const           /* Solaris, HP-UX, AIX */
  68 #else
  69 # define sshpam_const   const   /* LinuxPAM, OpenPAM */
  70 #endif
  71
  72 #include "auth.h"
  73 #include "auth-pam.h"
  74 #include "buffer.h"
  75 #include "bufaux.h"
  76 #include "canohost.h"
  77 #include "log.h"
  78 #include "monitor_wrap.h"
  79 #include "msg.h"
  80 #include "packet.h"
  81 #include "misc.h"
  82 #include "servconf.h"
  83 #include "ssh2.h"
  84 #include "xmalloc.h"
  85 #include "auth-options.h"
  86
  87 extern ServerOptions options;
  88 extern Buffer loginmsg;
  89 extern int compat20;
  90 extern u_int utmp_len;
  91
  92 /* so we don't silently change behaviour */
  93 #ifdef USE_POSIX_THREADS
  94 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
  95 #endif
  96
  97 /*
  98  * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
  99  * and generally a bad idea.  Use at own risk and do not expect support if
 100  * this breaks.
 101  */
 102 #ifdef UNSUPPORTED_POSIX_THREADS_HACK
 103 #include <pthread.h>
 104 /*
 105  * Avoid namespace clash when *not* using pthreads for systems *with*
 106  * pthreads, which unconditionally define pthread_t via sys/types.h
 107  * (e.g. Linux)
 108  */
 109 typedef pthread_t sp_pthread_t;
 110 #else
 111 typedef pid_t sp_pthread_t;
 112 #endif
 113
 114 struct pam_ctxt {
 115         sp_pthread_t     pam_thread;
 116         int              pam_psock;
 117         int              pam_csock;
 118         int              pam_done;
 119 };
 120
 121 static void sshpam_free_ctx(void *);
 122 static struct pam_ctxt *cleanup_ctxt;
 123
 124 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 125 /*
 126  * Simulate threads with processes.
 127  */
 128
 129 static int sshpam_thread_status = -1;
 130 static mysig_t sshpam_oldsig;
 131
 132 static void
 133 sshpam_sigchld_handler(int sig)
 134 {
 135         signal(SIGCHLD, SIG_DFL);
 136         if (cleanup_ctxt == NULL)
 137                 return; /* handler called after PAM cleanup, shouldn't happen */
 138         if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
 139             <= 0) {
 140                 /* PAM thread has not exitted, privsep slave must have */
 141                 kill(cleanup_ctxt->pam_thread, SIGTERM);
 142                 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0)
 143                     <= 0)
 144                         return; /* could not wait */
 145         }
 146         if (WIFSIGNALED(sshpam_thread_status) &&
 147             WTERMSIG(sshpam_thread_status) == SIGTERM)
 148                 return; /* terminated by pthread_cancel */
 149         if (!WIFEXITED(sshpam_thread_status))
 150                 fatal("PAM: authentication thread exited unexpectedly");
 151         if (WEXITSTATUS(sshpam_thread_status) != 0)
 152                 fatal("PAM: authentication thread exited uncleanly");
 153 }
 154
 155 static void
 156 pthread_exit(void *value __unused)
 157 {
 158         _exit(0);
 159 }
 160
 161 static int
 162 pthread_create(sp_pthread_t *thread, const void *attr __unused,
 163     void *(*thread_start)(void *), void *arg)
 164 {
 165         pid_t pid;
 166         struct pam_ctxt *ctx = arg;
 167
 168         sshpam_thread_status = -1;
 169         switch ((pid = fork())) {
 170         case -1:
 171                 error("fork(): %s", strerror(errno));
 172                 return (-1);
 173         case 0:
 174                 close(ctx->pam_psock);
 175                 ctx->pam_psock = -1;
 176                 thread_start(arg);
 177                 _exit(1);
 178         default:
 179                 *thread = pid;
 180                 close(ctx->pam_csock);
 181                 ctx->pam_csock = -1;
 182                 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
 183                 return (0);
 184         }
 185 }
 186
 187 static int
 188 pthread_cancel(sp_pthread_t thread)
 189 {
 190         signal(SIGCHLD, sshpam_oldsig);
 191         return (kill(thread, SIGTERM));
 192 }
 193
 194 static int
 195 pthread_join(sp_pthread_t thread, void **value __unused)
 196 {
 197         int status;
 198
 199         if (sshpam_thread_status != -1)
 200                 return (sshpam_thread_status);
 201         signal(SIGCHLD, sshpam_oldsig);
 202         waitpid(thread, &status, 0);
 203         return (status);
 204 }
 205 #endif
 206
 207
 208 static pam_handle_t *sshpam_handle = NULL;
 209 static int sshpam_err = 0;
 210 static int sshpam_authenticated = 0;
 211 static int sshpam_session_open = 0;
 212 static int sshpam_cred_established = 0;
 213 static int sshpam_account_status = -1;
 214 static char **sshpam_env = NULL;
 215 static Authctxt *sshpam_authctxt = NULL;
 216 static const char *sshpam_password = NULL;
 217 static char badpw[] = "\b\n\r\177INCORRECT";
 218
 219 /* Some PAM implementations don't implement this */
 220 #ifndef HAVE_PAM_GETENVLIST
 221 static char **
 222 pam_getenvlist(pam_handle_t *pamh)
 223 {
 224         /*
 225          * XXX - If necessary, we can still support envrionment passing
 226          * for platforms without pam_getenvlist by searching for known
 227          * env vars (e.g. KRB5CCNAME) from the PAM environment.
 228          */
 229          return NULL;
 230 }
 231 #endif
 232
 233 /*
 234  * Some platforms, notably Solaris, do not enforce password complexity
 235  * rules during pam_chauthtok() if the real uid of the calling process
 236  * is 0, on the assumption that it's being called by "passwd" run by root.
 237  * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
 238  * the right thing.
 239  */
 240 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
 241 static int
 242 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
 243 {
 244         int result;
 245
 246         if (sshpam_authctxt == NULL)
 247                 fatal("PAM: sshpam_authctxt not initialized");
 248         if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
 249                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 250         result = pam_chauthtok(pamh, flags);
 251         if (setreuid(0, -1) == -1)
 252                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 253         return result;
 254 }
 255 # define pam_chauthtok(a,b)     (sshpam_chauthtok_ruid((a), (b)))
 256 #endif
 257
 258 void
 259 sshpam_password_change_required(int reqd)
 260 {
 261         debug3("%s %d", __func__, reqd);
 262         if (sshpam_authctxt == NULL)
 263                 fatal("%s: PAM authctxt not initialized", __func__);
 264         sshpam_authctxt->force_pwchange = reqd;
 265         if (reqd) {
 266                 no_port_forwarding_flag |= 2;
 267                 no_agent_forwarding_flag |= 2;
 268                 no_x11_forwarding_flag |= 2;
 269         } else {
 270                 no_port_forwarding_flag &= ~2;
 271                 no_agent_forwarding_flag &= ~2;
 272                 no_x11_forwarding_flag &= ~2;
 273         }
 274 }
 275
 276 /* Import regular and PAM environment from subprocess */
 277 static void
 278 import_environments(Buffer *b)
 279 {
 280         char *env;
 281         u_int i, num_env;
 282         int err;
 283
 284         debug3("PAM: %s entering", __func__);
 285
 286 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 287         /* Import variables set by do_pam_account */
 288         sshpam_account_status = buffer_get_int(b);
 289         sshpam_password_change_required(buffer_get_int(b));
 290
 291         /* Import environment from subprocess */
 292         num_env = buffer_get_int(b);
 293         if (num_env > 1024)
 294                 fatal("%s: received %u environment variables, expected <= 1024",
 295                     __func__, num_env);
 296         sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env));
 297         debug3("PAM: num env strings %d", num_env);
 298         for(i = 0; i < num_env; i++)
 299                 sshpam_env[i] = buffer_get_string(b, NULL);
 300
 301         sshpam_env[num_env] = NULL;
 302
 303         /* Import PAM environment from subprocess */
 304         num_env = buffer_get_int(b);
 305         debug("PAM: num PAM env strings %d", num_env);
 306         for(i = 0; i < num_env; i++) {
 307                 env = buffer_get_string(b, NULL);
 308
 309 #ifdef HAVE_PAM_PUTENV
 310                 /* Errors are not fatal here */
 311                 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
 312                         error("PAM: pam_putenv: %s",
 313                             pam_strerror(sshpam_handle, sshpam_err));
 314                 }
 315 #endif
 316         }
 317 #endif
 318 }
 319
 320 /*
 321  * Conversation function for authentication thread.
 322  */
 323 static int
 324 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
 325     struct pam_response **resp, void *data)
 326 {
 327         Buffer buffer;
 328         struct pam_ctxt *ctxt;
 329         struct pam_response *reply;
 330         int i;
 331
 332         debug3("PAM: %s entering, %d messages", __func__, n);
 333         *resp = NULL;
 334
 335         if (data == NULL) {
 336                 error("PAM: conversation function passed a null context");
 337                 return (PAM_CONV_ERR);
 338         }
 339         ctxt = data;
 340         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 341                 return (PAM_CONV_ERR);
 342
 343         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 344                 return (PAM_CONV_ERR);
 345
 346         buffer_init(&buffer);
 347         for (i = 0; i < n; ++i) {
 348                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 349                 case PAM_PROMPT_ECHO_OFF:
 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                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 356                                 goto fail;
 357                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 358                                 goto fail;
 359                         reply[i].resp = buffer_get_string(&buffer, NULL);
 360                         break;
 361                 case PAM_PROMPT_ECHO_ON:
 362                         buffer_put_cstring(&buffer,
 363                             PAM_MSG_MEMBER(msg, i, msg));
 364                         if (ssh_msg_send(ctxt->pam_csock,
 365                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 366                                 goto fail;
 367                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 368                                 goto fail;
 369                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 370                                 goto fail;
 371                         reply[i].resp = buffer_get_string(&buffer, NULL);
 372                         break;
 373                 case PAM_ERROR_MSG:
 374                         buffer_put_cstring(&buffer,
 375                             PAM_MSG_MEMBER(msg, i, msg));
 376                         if (ssh_msg_send(ctxt->pam_csock,
 377                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 378                                 goto fail;
 379                         break;
 380                 case PAM_TEXT_INFO:
 381                         buffer_put_cstring(&buffer,
 382                             PAM_MSG_MEMBER(msg, i, msg));
 383                         if (ssh_msg_send(ctxt->pam_csock,
 384                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 385                                 goto fail;
 386                         break;
 387                 default:
 388                         goto fail;
 389                 }
 390                 buffer_clear(&buffer);
 391         }
 392         buffer_free(&buffer);
 393         *resp = reply;
 394         return (PAM_SUCCESS);
 395
 396  fail:
 397         for(i = 0; i < n; i++) {
 398                 if (reply[i].resp != NULL)
 399                         xfree(reply[i].resp);
 400         }
 401         xfree(reply);
 402         buffer_free(&buffer);
 403         return (PAM_CONV_ERR);
 404 }
 405
 406 /*
 407  * Authentication thread.
 408  */
 409 static void *
 410 sshpam_thread(void *ctxtp)
 411 {
 412         struct pam_ctxt *ctxt = ctxtp;
 413         Buffer buffer;
 414         struct pam_conv sshpam_conv;
 415         int flags = (options.permit_empty_passwd == 0 ?
 416             PAM_DISALLOW_NULL_AUTHTOK : 0);
 417 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 418         extern char **environ;
 419         char **env_from_pam;
 420         u_int i;
 421         const char *pam_user;
 422         const char **ptr_pam_user = &pam_user;
 423
 424         pam_get_item(sshpam_handle, PAM_USER,
 425             (sshpam_const void **)ptr_pam_user);
 426         environ[0] = NULL;
 427
 428         if (sshpam_authctxt != NULL) {
 429                 setproctitle("%s [pam]",
 430                     sshpam_authctxt->valid ? pam_user : "unknown");
 431         }
 432 #endif
 433
 434         sshpam_conv.conv = sshpam_thread_conv;
 435         sshpam_conv.appdata_ptr = ctxt;
 436
 437         if (sshpam_authctxt == NULL)
 438                 fatal("%s: PAM authctxt not initialized", __func__);
 439
 440         buffer_init(&buffer);
 441         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 442             (const void *)&sshpam_conv);
 443         if (sshpam_err != PAM_SUCCESS)
 444                 goto auth_fail;
 445         sshpam_err = pam_authenticate(sshpam_handle, flags);
 446         if (sshpam_err != PAM_SUCCESS)
 447                 goto auth_fail;
 448
 449         if (compat20) {
 450                 if (!do_pam_account()) {
 451                         sshpam_err = PAM_ACCT_EXPIRED;
 452                         goto auth_fail;
 453                 }
 454                 if (sshpam_authctxt->force_pwchange) {
 455                         sshpam_err = pam_chauthtok(sshpam_handle,
 456                             PAM_CHANGE_EXPIRED_AUTHTOK);
 457                         if (sshpam_err != PAM_SUCCESS)
 458                                 goto auth_fail;
 459                         sshpam_password_change_required(0);
 460                 }
 461         }
 462
 463         buffer_put_cstring(&buffer, "OK");
 464
 465 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 466         /* Export variables set by do_pam_account */
 467         buffer_put_int(&buffer, sshpam_account_status);
 468         buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);
 469
 470         /* Export any environment strings set in child */
 471         for(i = 0; environ[i] != NULL; i++)
 472                 ; /* Count */
 473         buffer_put_int(&buffer, i);
 474         for(i = 0; environ[i] != NULL; i++)
 475                 buffer_put_cstring(&buffer, environ[i]);
 476
 477         /* Export any environment strings set by PAM in child */
 478         env_from_pam = pam_getenvlist(sshpam_handle);
 479         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 480                 ; /* Count */
 481         buffer_put_int(&buffer, i);
 482         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 483                 buffer_put_cstring(&buffer, env_from_pam[i]);
 484 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */
 485
 486         /* XXX - can't do much about an error here */
 487         ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
 488         buffer_free(&buffer);
 489         pthread_exit(NULL);
 490
 491  auth_fail:
 492         buffer_put_cstring(&buffer,
 493             pam_strerror(sshpam_handle, sshpam_err));
 494         /* XXX - can't do much about an error here */
 495         if (sshpam_err == PAM_ACCT_EXPIRED)
 496                 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, &buffer);
 497         else
 498                 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
 499         buffer_free(&buffer);
 500         pthread_exit(NULL);
 501
 502         return (NULL); /* Avoid warning for non-pthread case */
 503 }
 504
 505 void
 506 sshpam_thread_cleanup(void)
 507 {
 508         struct pam_ctxt *ctxt = cleanup_ctxt;
 509
 510         debug3("PAM: %s entering", __func__);
 511         if (ctxt != NULL && ctxt->pam_thread != 0) {
 512                 pthread_cancel(ctxt->pam_thread);
 513                 pthread_join(ctxt->pam_thread, NULL);
 514                 close(ctxt->pam_psock);
 515                 close(ctxt->pam_csock);
 516                 memset(ctxt, 0, sizeof(*ctxt));
 517                 cleanup_ctxt = NULL;
 518         }
 519 }
 520
 521 static int
 522 sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
 523     struct pam_response **resp, void *data)
 524 {
 525         debug3("PAM: %s entering, %d messages", __func__, n);
 526         return (PAM_CONV_ERR);
 527 }
 528
 529 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
 530
 531 static int
 532 sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
 533     struct pam_response **resp, void *data)
 534 {
 535         struct pam_response *reply;
 536         int i;
 537         size_t len;
 538
 539         debug3("PAM: %s called with %d messages", __func__, n);
 540         *resp = NULL;
 541
 542         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 543                 return (PAM_CONV_ERR);
 544
 545         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 546                 return (PAM_CONV_ERR);
 547
 548         for (i = 0; i < n; ++i) {
 549                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 550                 case PAM_ERROR_MSG:
 551                 case PAM_TEXT_INFO:
 552                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
 553                         buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
 554                         buffer_append(&loginmsg, "\n", 1 );
 555                         reply[i].resp_retcode = PAM_SUCCESS;
 556                         break;
 557                 default:
 558                         goto fail;
 559                 }
 560         }
 561         *resp = reply;
 562         return (PAM_SUCCESS);
 563
 564  fail:
 565         for(i = 0; i < n; i++) {
 566                 if (reply[i].resp != NULL)
 567                         xfree(reply[i].resp);
 568         }
 569         xfree(reply);
 570         return (PAM_CONV_ERR);
 571 }
 572
 573 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
 574
 575 void
 576 sshpam_cleanup(void)
 577 {
 578         debug("PAM: cleanup");
 579         if (sshpam_handle == NULL)
 580                 return;
 581         pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 582         if (sshpam_cred_established) {
 583                 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
 584                 sshpam_cred_established = 0;
 585         }
 586         if (sshpam_session_open) {
 587                 pam_close_session(sshpam_handle, PAM_SILENT);
 588                 sshpam_session_open = 0;
 589         }
 590         sshpam_authenticated = 0;
 591         pam_end(sshpam_handle, sshpam_err);
 592         sshpam_handle = NULL;
 593 }
 594
 595 static int
 596 sshpam_init(Authctxt *authctxt)
 597 {
 598         extern char *__progname;
 599         const char *pam_rhost, *pam_user, *user = authctxt->user;
 600         const char **ptr_pam_user = &pam_user;
 601
 602         if (sshpam_handle != NULL) {
 603                 /* We already have a PAM context; check if the user matches */
 604                 sshpam_err = pam_get_item(sshpam_handle,
 605                     PAM_USER, (sshpam_const void **)ptr_pam_user);
 606                 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
 607                         return (0);
 608                 pam_end(sshpam_handle, sshpam_err);
 609                 sshpam_handle = NULL;
 610         }
 611         debug("PAM: initializing for \"%s\"", user);
 612         sshpam_err =
 613             pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
 614         sshpam_authctxt = authctxt;
 615
 616         if (sshpam_err != PAM_SUCCESS) {
 617                 pam_end(sshpam_handle, sshpam_err);
 618                 sshpam_handle = NULL;
 619                 return (-1);
 620         }
 621         pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
 622         debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
 623         sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
 624         if (sshpam_err != PAM_SUCCESS) {
 625                 pam_end(sshpam_handle, sshpam_err);
 626                 sshpam_handle = NULL;
 627                 return (-1);
 628         }
 629 #ifdef PAM_TTY_KLUDGE
 630         /*
 631          * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
 632          * sshd doesn't set the tty until too late in the auth process and
 633          * may not even set one (for tty-less connections)
 634          */
 635         debug("PAM: setting PAM_TTY to \"ssh\"");
 636         sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
 637         if (sshpam_err != PAM_SUCCESS) {
 638                 pam_end(sshpam_handle, sshpam_err);
 639                 sshpam_handle = NULL;
 640                 return (-1);
 641         }
 642 #endif
 643         return (0);
 644 }
 645
 646 static void *
 647 sshpam_init_ctx(Authctxt *authctxt)
 648 {
 649         struct pam_ctxt *ctxt;
 650         int socks[2];
 651
 652         debug3("PAM: %s entering", __func__);
 653         /*
 654          * Refuse to start if we don't have PAM enabled or do_pam_account
 655          * has previously failed.
 656          */
 657         if (!options.use_pam || sshpam_account_status == 0)
 658                 return NULL;
 659
 660         /* Initialize PAM */
 661         if (sshpam_init(authctxt) == -1) {
 662                 error("PAM: initialization failed");
 663                 return (NULL);
 664         }
 665
 666         ctxt = xmalloc(sizeof *ctxt);
 667         memset(ctxt, 0, sizeof(*ctxt));
 668
 669         /* Start the authentication thread */
 670         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
 671                 error("PAM: failed create sockets: %s", strerror(errno));
 672                 xfree(ctxt);
 673                 return (NULL);
 674         }
 675         ctxt->pam_psock = socks[0];
 676         ctxt->pam_csock = socks[1];
 677         if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
 678                 error("PAM: failed to start authentication thread: %s",
 679                     strerror(errno));
 680                 close(socks[0]);
 681                 close(socks[1]);
 682                 xfree(ctxt);
 683                 return (NULL);
 684         }
 685         cleanup_ctxt = ctxt;
 686         return (ctxt);
 687 }
 688
 689 static int
 690 sshpam_query(void *ctx, char **name, char **info,
 691     u_int *num, char ***prompts, u_int **echo_on)
 692 {
 693         Buffer buffer;
 694         struct pam_ctxt *ctxt = ctx;
 695         size_t plen;
 696         u_char type;
 697         char *msg;
 698         size_t len, mlen;
 699
 700         debug3("PAM: %s entering", __func__);
 701         buffer_init(&buffer);
 702         *name = xstrdup("");
 703         *info = xstrdup("");
 704         *prompts = xmalloc(sizeof(char *));
 705         **prompts = NULL;
 706         plen = 0;
 707         *echo_on = xmalloc(sizeof(u_int));
 708         while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
 709                 type = buffer_get_char(&buffer);
 710                 msg = buffer_get_string(&buffer, NULL);
 711                 mlen = strlen(msg);
 712                 switch (type) {
 713                 case PAM_PROMPT_ECHO_ON:
 714                 case PAM_PROMPT_ECHO_OFF:
 715                         *num = 1;
 716                         len = plen + mlen + 1;
 717                         **prompts = xrealloc(**prompts, 1, len);
 718                         strlcpy(**prompts + plen, msg, len - plen);
 719                         plen += mlen;
 720                         **echo_on = (type == PAM_PROMPT_ECHO_ON);
 721                         xfree(msg);
 722                         return (0);
 723                 case PAM_ERROR_MSG:
 724                 case PAM_TEXT_INFO:
 725                         /* accumulate messages */
 726                         len = plen + mlen + 2;
 727                         **prompts = xrealloc(**prompts, 1, len);
 728                         strlcpy(**prompts + plen, msg, len - plen);
 729                         plen += mlen;
 730                         strlcat(**prompts + plen, "\n", len - plen);
 731                         plen++;
 732                         xfree(msg);
 733                         break;
 734                 case PAM_ACCT_EXPIRED:
 735                         sshpam_account_status = 0;
 736                         /* FALLTHROUGH */
 737                 case PAM_AUTH_ERR:
 738                         debug3("PAM: %s", pam_strerror(sshpam_handle, type));
 739                         if (**prompts != NULL && strlen(**prompts) != 0) {
 740                                 *info = **prompts;
 741                                 **prompts = NULL;
 742                                 *num = 0;
 743                                 **echo_on = 0;
 744                                 ctxt->pam_done = -1;
 745                                 xfree(msg);
 746                                 return 0;
 747                         }
 748                         /* FALLTHROUGH */
 749                 case PAM_SUCCESS:
 750                         if (**prompts != NULL) {
 751                                 /* drain any accumulated messages */
 752                                 debug("PAM: %s", **prompts);
 753                                 buffer_append(&loginmsg, **prompts,
 754                                     strlen(**prompts));
 755                                 xfree(**prompts);
 756                                 **prompts = NULL;
 757                         }
 758                         if (type == PAM_SUCCESS) {
 759                                 if (!sshpam_authctxt->valid ||
 760                                     (sshpam_authctxt->pw->pw_uid == 0 &&
 761                                     options.permit_root_login != PERMIT_YES))
 762                                         fatal("Internal error: PAM auth "
 763                                             "succeeded when it should have "
 764                                             "failed");
 765                                 import_environments(&buffer);
 766                                 *num = 0;
 767                                 **echo_on = 0;
 768                                 ctxt->pam_done = 1;
 769                                 xfree(msg);
 770                                 return (0);
 771                         }
 772                         error("PAM: %s for %s%.100s from %.100s", msg,
 773                             sshpam_authctxt->valid ? "" : "illegal user ",
 774                             sshpam_authctxt->user,
 775                             get_remote_name_or_ip(utmp_len, options.use_dns));
 776                         /* FALLTHROUGH */
 777                 default:
 778                         *num = 0;
 779                         **echo_on = 0;
 780                         xfree(msg);
 781                         ctxt->pam_done = -1;
 782                         return (-1);
 783                 }
 784         }
 785         return (-1);
 786 }
 787
 788 /* XXX - see also comment in auth-chall.c:verify_response */
 789 static int
 790 sshpam_respond(void *ctx, u_int num, char **resp)
 791 {
 792         Buffer buffer;
 793         struct pam_ctxt *ctxt = ctx;
 794
 795         debug2("PAM: %s entering, %u responses", __func__, num);
 796         switch (ctxt->pam_done) {
 797         case 1:
 798                 sshpam_authenticated = 1;
 799                 return (0);
 800         case 0:
 801                 break;
 802         default:
 803                 return (-1);
 804         }
 805         if (num != 1) {
 806                 error("PAM: expected one response, got %u", num);
 807                 return (-1);
 808         }
 809         buffer_init(&buffer);
 810         if (sshpam_authctxt->valid &&
 811             (sshpam_authctxt->pw->pw_uid != 0 ||
 812             options.permit_root_login == PERMIT_YES))
 813                 buffer_put_cstring(&buffer, *resp);
 814         else
 815                 buffer_put_cstring(&buffer, badpw);
 816         if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
 817                 buffer_free(&buffer);
 818                 return (-1);
 819         }
 820         buffer_free(&buffer);
 821         return (1);
 822 }
 823
 824 static void
 825 sshpam_free_ctx(void *ctxtp)
 826 {
 827         struct pam_ctxt *ctxt = ctxtp;
 828
 829         debug3("PAM: %s entering", __func__);
 830         sshpam_thread_cleanup();
 831         xfree(ctxt);
 832         /*
 833          * We don't call sshpam_cleanup() here because we may need the PAM
 834          * handle at a later stage, e.g. when setting up a session.  It's
 835          * still on the cleanup list, so pam_end() *will* be called before
 836          * the server process terminates.
 837          */
 838 }
 839
 840 KbdintDevice sshpam_device = {
 841         "pam",
 842         sshpam_init_ctx,
 843         sshpam_query,
 844         sshpam_respond,
 845         sshpam_free_ctx
 846 };
 847
 848 KbdintDevice mm_sshpam_device = {
 849         "pam",
 850         mm_sshpam_init_ctx,
 851         mm_sshpam_query,
 852         mm_sshpam_respond,
 853         mm_sshpam_free_ctx
 854 };
 855
 856 /*
 857  * This replaces auth-pam.c
 858  */
 859 void
 860 start_pam(Authctxt *authctxt)
 861 {
 862         if (!options.use_pam)
 863                 fatal("PAM: initialisation requested when UsePAM=no");
 864
 865         if (sshpam_init(authctxt) == -1)
 866                 fatal("PAM: initialisation failed");
 867 }
 868
 869 void
 870 finish_pam(void)
 871 {
 872         sshpam_cleanup();
 873 }
 874
 875 u_int
 876 do_pam_account(void)
 877 {
 878         debug("%s: called", __func__);
 879         if (sshpam_account_status != -1)
 880                 return (sshpam_account_status);
 881
 882         sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
 883         debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
 884             pam_strerror(sshpam_handle, sshpam_err));
 885
 886         if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
 887                 sshpam_account_status = 0;
 888                 return (sshpam_account_status);
 889         }
 890
 891         if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
 892                 sshpam_password_change_required(1);
 893
 894         sshpam_account_status = 1;
 895         return (sshpam_account_status);
 896 }
 897
 898 void
 899 do_pam_set_tty(const char *tty)
 900 {
 901         if (tty != NULL) {
 902                 debug("PAM: setting PAM_TTY to \"%s\"", tty);
 903                 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
 904                 if (sshpam_err != PAM_SUCCESS)
 905                         fatal("PAM: failed to set PAM_TTY: %s",
 906                             pam_strerror(sshpam_handle, sshpam_err));
 907         }
 908 }
 909
 910 void
 911 do_pam_setcred(int init)
 912 {
 913         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 914             (const void *)&store_conv);
 915         if (sshpam_err != PAM_SUCCESS)
 916                 fatal("PAM: failed to set PAM_CONV: %s",
 917                     pam_strerror(sshpam_handle, sshpam_err));
 918         if (init) {
 919                 debug("PAM: establishing credentials");
 920                 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
 921         } else {
 922                 debug("PAM: reinitializing credentials");
 923                 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
 924         }
 925         if (sshpam_err == PAM_SUCCESS) {
 926                 sshpam_cred_established = 1;
 927                 return;
 928         }
 929         if (sshpam_authenticated)
 930                 fatal("PAM: pam_setcred(): %s",
 931                     pam_strerror(sshpam_handle, sshpam_err));
 932         else
 933                 debug("PAM: pam_setcred(): %s",
 934                     pam_strerror(sshpam_handle, sshpam_err));
 935 }
 936
 937 static int
 938 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
 939     struct pam_response **resp, void *data)
 940 {
 941         char input[PAM_MAX_MSG_SIZE];
 942         struct pam_response *reply;
 943         int i;
 944
 945         debug3("PAM: %s called with %d messages", __func__, n);
 946
 947         *resp = NULL;
 948
 949         if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
 950                 return (PAM_CONV_ERR);
 951
 952         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 953                 return (PAM_CONV_ERR);
 954
 955         for (i = 0; i < n; ++i) {
 956                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 957                 case PAM_PROMPT_ECHO_OFF:
 958                         reply[i].resp =
 959                             read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
 960                             RP_ALLOW_STDIN);
 961                         reply[i].resp_retcode = PAM_SUCCESS;
 962                         break;
 963                 case PAM_PROMPT_ECHO_ON:
 964                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 965                         fgets(input, sizeof input, stdin);
 966                         if ((reply[i].resp = strdup(input)) == NULL)
 967                                 goto fail;
 968                         reply[i].resp_retcode = PAM_SUCCESS;
 969                         break;
 970                 case PAM_ERROR_MSG:
 971                 case PAM_TEXT_INFO:
 972                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 973                         reply[i].resp_retcode = PAM_SUCCESS;
 974                         break;
 975                 default:
 976                         goto fail;
 977                 }
 978         }
 979         *resp = reply;
 980         return (PAM_SUCCESS);
 981
 982  fail:
 983         for(i = 0; i < n; i++) {
 984                 if (reply[i].resp != NULL)
 985                         xfree(reply[i].resp);
 986         }
 987         xfree(reply);
 988         return (PAM_CONV_ERR);
 989 }
 990
 991 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
 992
 993 /*
 994  * XXX this should be done in the authentication phase, but ssh1 doesn't
 995  * support that
 996  */
 997 void
 998 do_pam_chauthtok(void)
 999 {
1000         if (use_privsep)
1001                 fatal("Password expired (unable to change with privsep)");
1002         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1003             (const void *)&tty_conv);
1004         if (sshpam_err != PAM_SUCCESS)
1005                 fatal("PAM: failed to set PAM_CONV: %s",
1006                     pam_strerror(sshpam_handle, sshpam_err));
1007         debug("PAM: changing password");
1008         sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
1009         if (sshpam_err != PAM_SUCCESS)
1010                 fatal("PAM: pam_chauthtok(): %s",
1011                     pam_strerror(sshpam_handle, sshpam_err));
1012 }
1013
1014 void
1015 do_pam_session(void)
1016 {
1017         debug3("PAM: opening session");
1018         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1019             (const void *)&store_conv);
1020         if (sshpam_err != PAM_SUCCESS)
1021                 fatal("PAM: failed to set PAM_CONV: %s",
1022                     pam_strerror(sshpam_handle, sshpam_err));
1023         sshpam_err = pam_open_session(sshpam_handle, 0);
1024         if (sshpam_err == PAM_SUCCESS)
1025                 sshpam_session_open = 1;
1026         else {
1027                 sshpam_session_open = 0;
1028                 disable_forwarding();
1029                 error("PAM: pam_open_session(): %s",
1030                     pam_strerror(sshpam_handle, sshpam_err));
1031         }
1032
1033 }
1034
1035 int
1036 is_pam_session_open(void)
1037 {
1038         return sshpam_session_open;
1039 }
1040
1041 /*
1042  * Set a PAM environment string. We need to do this so that the session
1043  * modules can handle things like Kerberos/GSI credentials that appear
1044  * during the ssh authentication process.
1045  */
1046 int
1047 do_pam_putenv(char *name, char *value)
1048 {
1049         int ret = 1;
1050 #ifdef HAVE_PAM_PUTENV
1051         char *compound;
1052         size_t len;
1053
1054         len = strlen(name) + strlen(value) + 2;
1055         compound = xmalloc(len);
1056
1057         snprintf(compound, len, "%s=%s", name, value);
1058         ret = pam_putenv(sshpam_handle, compound);
1059         xfree(compound);
1060 #endif
1061
1062         return (ret);
1063 }
1064
1065 char **
1066 fetch_pam_child_environment(void)
1067 {
1068         return sshpam_env;
1069 }
1070
1071 char **
1072 fetch_pam_environment(void)
1073 {
1074         return (pam_getenvlist(sshpam_handle));
1075 }
1076
1077 void
1078 free_pam_environment(char **env)
1079 {
1080         char **envp;
1081
1082         if (env == NULL)
1083                 return;
1084
1085         for (envp = env; *envp; envp++)
1086                 xfree(*envp);
1087         xfree(env);
1088 }
1089
1090 /*
1091  * "Blind" conversation function for password authentication.  Assumes that
1092  * echo-off prompts are for the password and stores messages for later
1093  * display.
1094  */
1095 static int
1096 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1097     struct pam_response **resp, void *data)
1098 {
1099         struct pam_response *reply;
1100         int i;
1101         size_t len;
1102
1103         debug3("PAM: %s called with %d messages", __func__, n);
1104
1105         *resp = NULL;
1106
1107         if (n <= 0 || n > PAM_MAX_NUM_MSG)
1108                 return (PAM_CONV_ERR);
1109
1110         if ((reply = malloc(n * sizeof(*reply))) == NULL)
1111                 return (PAM_CONV_ERR);
1112         memset(reply, 0, n * sizeof(*reply));
1113
1114         for (i = 0; i < n; ++i) {
1115                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1116                 case PAM_PROMPT_ECHO_OFF:
1117                         if (sshpam_password == NULL)
1118                                 goto fail;
1119                         if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1120                                 goto fail;
1121                         reply[i].resp_retcode = PAM_SUCCESS;
1122                         break;
1123                 case PAM_ERROR_MSG:
1124                 case PAM_TEXT_INFO:
1125                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1126                         if (len > 0) {
1127                                 buffer_append(&loginmsg,
1128                                     PAM_MSG_MEMBER(msg, i, msg), len);
1129                                 buffer_append(&loginmsg, "\n", 1);
1130                         }
1131                         if ((reply[i].resp = strdup("")) == NULL)
1132                                 goto fail;
1133                         reply[i].resp_retcode = PAM_SUCCESS;
1134                         break;
1135                 default:
1136                         goto fail;
1137                 }
1138         }
1139         *resp = reply;
1140         return (PAM_SUCCESS);
1141
1142  fail:
1143         for(i = 0; i < n; i++) {
1144                 if (reply[i].resp != NULL)
1145                         xfree(reply[i].resp);
1146         }
1147         xfree(reply);
1148         return (PAM_CONV_ERR);
1149 }
1150
1151 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1152
1153 /*
1154  * Attempt password authentication via PAM
1155  */
1156 int
1157 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1158 {
1159         int flags = (options.permit_empty_passwd == 0 ?
1160             PAM_DISALLOW_NULL_AUTHTOK : 0);
1161
1162         if (!options.use_pam || sshpam_handle == NULL)
1163                 fatal("PAM: %s called when PAM disabled or failed to "
1164                     "initialise.", __func__);
1165
1166         sshpam_password = password;
1167         sshpam_authctxt = authctxt;
1168
1169         /*
1170          * If the user logging in is invalid, or is root but is not permitted
1171          * by PermitRootLogin, use an invalid password to prevent leaking
1172          * information via timing (eg if the PAM config has a delay on fail).
1173          */
1174         if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1175             options.permit_root_login != PERMIT_YES))
1176                 sshpam_password = badpw;
1177
1178         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1179             (const void *)&passwd_conv);
1180         if (sshpam_err != PAM_SUCCESS)
1181                 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1182                     pam_strerror(sshpam_handle, sshpam_err));
1183
1184         sshpam_err = pam_authenticate(sshpam_handle, flags);
1185         sshpam_password = NULL;
1186         if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1187                 debug("PAM: password authentication accepted for %.100s",
1188                     authctxt->user);
1189                 return 1;
1190         } else {
1191                 debug("PAM: password authentication failed for %.100s: %s",
1192                     authctxt->valid ? authctxt->user : "an illegal user",
1193                     pam_strerror(sshpam_handle, sshpam_err));
1194                 return 0;
1195         }
1196 }
1197 #endif /* USE_PAM */