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