auth-pam.c

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