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 #include <string.h>
  58 #include <unistd.h>
  59
  60 #ifdef USE_PAM
  61 #if defined(HAVE_SECURITY_PAM_APPL_H)
  62 #include <security/pam_appl.h>
  63 #elif defined (HAVE_PAM_PAM_APPL_H)
  64 #include <pam/pam_appl.h>
  65 #endif
  66
  67 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */
  68 #ifdef PAM_SUN_CODEBASE
  69 # define sshpam_const           /* Solaris, HP-UX, AIX */
  70 #else
  71 # define sshpam_const   const   /* LinuxPAM, OpenPAM */
  72 #endif
  73
  74 /* Ambiguity in spec: is it an array of pointers or a pointer to an array? */
  75 #ifdef PAM_SUN_CODEBASE
  76 # define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member)
  77 #else
  78 # define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member)
  79 #endif
  80
  81 #include "auth.h"
  82 #include "auth-pam.h"
  83 #include "buffer.h"
  84 #include "canohost.h"
  85 #include "log.h"
  86 #include "monitor_wrap.h"
  87 #include "msg.h"
  88 #include "packet.h"
  89 #include "misc.h"
  90 #include "servconf.h"
  91 #include "ssh2.h"
  92 #include "xmalloc.h"
  93 #include "auth-options.h"
  94
  95 extern ServerOptions options;
  96 extern Buffer loginmsg;
  97 extern int compat20;
  98 extern u_int utmp_len;
  99
 100 /* so we don't silently change behaviour */
 101 #ifdef USE_POSIX_THREADS
 102 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
 103 #endif
 104
 105 /*
 106  * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
 107  * and generally a bad idea.  Use at own risk and do not expect support if
 108  * this breaks.
 109  */
 110 #ifdef UNSUPPORTED_POSIX_THREADS_HACK
 111 #include <pthread.h>
 112 /*
 113  * Avoid namespace clash when *not* using pthreads for systems *with*
 114  * pthreads, which unconditionally define pthread_t via sys/types.h
 115  * (e.g. Linux)
 116  */
 117 typedef pthread_t sp_pthread_t;
 118 #else
 119 typedef pid_t sp_pthread_t;
 120 #endif
 121
 122 struct pam_ctxt {
 123         sp_pthread_t     pam_thread;
 124         int              pam_psock;
 125         int              pam_csock;
 126         int              pam_done;
 127 };
 128
 129 static void sshpam_free_ctx(void *);
 130 static struct pam_ctxt *cleanup_ctxt;
 131
 132 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 133 /*
 134  * Simulate threads with processes.
 135  */
 136
 137 static int sshpam_thread_status = -1;
 138 static mysig_t sshpam_oldsig;
 139
 140 static void
 141 sshpam_sigchld_handler(int sig)
 142 {
 143         signal(SIGCHLD, SIG_DFL);
 144         if (cleanup_ctxt == NULL)
 145                 return; /* handler called after PAM cleanup, shouldn't happen */
 146         if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
 147             <= 0) {
 148                 /* PAM thread has not exitted, privsep slave must have */
 149                 kill(cleanup_ctxt->pam_thread, SIGTERM);
 150                 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0)
 151                     <= 0)
 152                         return; /* could not wait */
 153         }
 154         if (WIFSIGNALED(sshpam_thread_status) &&
 155             WTERMSIG(sshpam_thread_status) == SIGTERM)
 156                 return; /* terminated by pthread_cancel */
 157         if (!WIFEXITED(sshpam_thread_status))
 158                 fatal("PAM: authentication thread exited unexpectedly");
 159         if (WEXITSTATUS(sshpam_thread_status) != 0)
 160                 fatal("PAM: authentication thread exited uncleanly");
 161 }
 162
 163 /* ARGSUSED */
 164 static void
 165 pthread_exit(void *value)
 166 {
 167         _exit(0);
 168 }
 169
 170 /* ARGSUSED */
 171 static int
 172 pthread_create(sp_pthread_t *thread, const void *attr,
 173     void *(*thread_start)(void *), void *arg)
 174 {
 175         pid_t pid;
 176         struct pam_ctxt *ctx = arg;
 177
 178         sshpam_thread_status = -1;
 179         switch ((pid = fork())) {
 180         case -1:
 181                 error("fork(): %s", strerror(errno));
 182                 return (-1);
 183         case 0:
 184                 close(ctx->pam_psock);
 185                 ctx->pam_psock = -1;
 186                 thread_start(arg);
 187                 _exit(1);
 188         default:
 189                 *thread = pid;
 190                 close(ctx->pam_csock);
 191                 ctx->pam_csock = -1;
 192                 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
 193                 return (0);
 194         }
 195 }
 196
 197 static int
 198 pthread_cancel(sp_pthread_t thread)
 199 {
 200         signal(SIGCHLD, sshpam_oldsig);
 201         return (kill(thread, SIGTERM));
 202 }
 203
 204 /* ARGSUSED */
 205 static int
 206 pthread_join(sp_pthread_t thread, void **value)
 207 {
 208         int status;
 209
 210         if (sshpam_thread_status != -1)
 211                 return (sshpam_thread_status);
 212         signal(SIGCHLD, sshpam_oldsig);
 213         waitpid(thread, &status, 0);
 214         return (status);
 215 }
 216 #endif
 217
 218
 219 static pam_handle_t *sshpam_handle = NULL;
 220 static int sshpam_err = 0;
 221 static int sshpam_authenticated = 0;
 222 static int sshpam_session_open = 0;
 223 static int sshpam_cred_established = 0;
 224 static int sshpam_account_status = -1;
 225 static char **sshpam_env = NULL;
 226 static Authctxt *sshpam_authctxt = NULL;
 227 static const char *sshpam_password = NULL;
 228 static char badpw[] = "\b\n\r\177INCORRECT";
 229
 230 /* Some PAM implementations don't implement this */
 231 #ifndef HAVE_PAM_GETENVLIST
 232 static char **
 233 pam_getenvlist(pam_handle_t *pamh)
 234 {
 235         /*
 236          * XXX - If necessary, we can still support envrionment passing
 237          * for platforms without pam_getenvlist by searching for known
 238          * env vars (e.g. KRB5CCNAME) from the PAM environment.
 239          */
 240          return NULL;
 241 }
 242 #endif
 243
 244 /*
 245  * Some platforms, notably Solaris, do not enforce password complexity
 246  * rules during pam_chauthtok() if the real uid of the calling process
 247  * is 0, on the assumption that it's being called by "passwd" run by root.
 248  * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
 249  * the right thing.
 250  */
 251 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
 252 static int
 253 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
 254 {
 255         int result;
 256
 257         if (sshpam_authctxt == NULL)
 258                 fatal("PAM: sshpam_authctxt not initialized");
 259         if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
 260                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 261         result = pam_chauthtok(pamh, flags);
 262         if (setreuid(0, -1) == -1)
 263                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 264         return result;
 265 }
 266 # define pam_chauthtok(a,b)     (sshpam_chauthtok_ruid((a), (b)))
 267 #endif
 268
 269 void
 270 sshpam_password_change_required(int reqd)
 271 {
 272         debug3("%s %d", __func__, reqd);
 273         if (sshpam_authctxt == NULL)
 274                 fatal("%s: PAM authctxt not initialized", __func__);
 275         sshpam_authctxt->force_pwchange = reqd;
 276         if (reqd) {
 277                 no_port_forwarding_flag |= 2;
 278                 no_agent_forwarding_flag |= 2;
 279                 no_x11_forwarding_flag |= 2;
 280         } else {
 281                 no_port_forwarding_flag &= ~2;
 282                 no_agent_forwarding_flag &= ~2;
 283                 no_x11_forwarding_flag &= ~2;
 284         }
 285 }
 286
 287 /* Import regular and PAM environment from subprocess */
 288 static void
 289 import_environments(Buffer *b)
 290 {
 291         char *env;
 292         u_int i, num_env;
 293         int err;
 294
 295         debug3("PAM: %s entering", __func__);
 296
 297 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 298         /* Import variables set by do_pam_account */
 299         sshpam_account_status = buffer_get_int(b);
 300         sshpam_password_change_required(buffer_get_int(b));
 301
 302         /* Import environment from subprocess */
 303         num_env = buffer_get_int(b);
 304         if (num_env > 1024)
 305                 fatal("%s: received %u environment variables, expected <= 1024",
 306                     __func__, num_env);
 307         sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env));
 308         debug3("PAM: num env strings %d", num_env);
 309         for(i = 0; i < num_env; i++)
 310                 sshpam_env[i] = buffer_get_string(b, NULL);
 311
 312         sshpam_env[num_env] = NULL;
 313
 314         /* Import PAM environment from subprocess */
 315         num_env = buffer_get_int(b);
 316         debug("PAM: num PAM env strings %d", num_env);
 317         for(i = 0; i < num_env; i++) {
 318                 env = buffer_get_string(b, NULL);
 319
 320 #ifdef HAVE_PAM_PUTENV
 321                 /* Errors are not fatal here */
 322                 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
 323                         error("PAM: pam_putenv: %s",
 324                             pam_strerror(sshpam_handle, sshpam_err));
 325                 }
 326 #endif
 327         }
 328 #endif
 329 }
 330
 331 /*
 332  * Conversation function for authentication thread.
 333  */
 334 static int
 335 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
 336     struct pam_response **resp, void *data)
 337 {
 338         Buffer buffer;
 339         struct pam_ctxt *ctxt;
 340         struct pam_response *reply;
 341         int i;
 342
 343         debug3("PAM: %s entering, %d messages", __func__, n);
 344         *resp = NULL;
 345
 346         if (data == NULL) {
 347                 error("PAM: conversation function passed a null context");
 348                 return (PAM_CONV_ERR);
 349         }
 350         ctxt = data;
 351         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 352                 return (PAM_CONV_ERR);
 353
 354         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 355                 return (PAM_CONV_ERR);
 356
 357         buffer_init(&buffer);
 358         for (i = 0; i < n; ++i) {
 359                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 360                 case PAM_PROMPT_ECHO_OFF:
 361                         buffer_put_cstring(&buffer,
 362                             PAM_MSG_MEMBER(msg, i, msg));
 363                         if (ssh_msg_send(ctxt->pam_csock,
 364                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 365                                 goto fail;
 366                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 367                                 goto fail;
 368                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 369                                 goto fail;
 370                         reply[i].resp = buffer_get_string(&buffer, NULL);
 371                         break;
 372                 case PAM_PROMPT_ECHO_ON:
 373                         buffer_put_cstring(&buffer,
 374                             PAM_MSG_MEMBER(msg, i, msg));
 375                         if (ssh_msg_send(ctxt->pam_csock,
 376                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 377                                 goto fail;
 378                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 379                                 goto fail;
 380                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 381                                 goto fail;
 382                         reply[i].resp = buffer_get_string(&buffer, NULL);
 383                         break;
 384                 case PAM_ERROR_MSG:
 385                         buffer_put_cstring(&buffer,
 386                             PAM_MSG_MEMBER(msg, i, msg));
 387                         if (ssh_msg_send(ctxt->pam_csock,
 388                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 389                                 goto fail;
 390                         break;
 391                 case PAM_TEXT_INFO:
 392                         buffer_put_cstring(&buffer,
 393                             PAM_MSG_MEMBER(msg, i, msg));
 394                         if (ssh_msg_send(ctxt->pam_csock,
 395                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 396                                 goto fail;
 397                         break;
 398                 default:
 399                         goto fail;
 400                 }
 401                 buffer_clear(&buffer);
 402         }
 403         buffer_free(&buffer);
 404         *resp = reply;
 405         return (PAM_SUCCESS);
 406
 407  fail:
 408         for(i = 0; i < n; i++) {
 409                 if (reply[i].resp != NULL)
 410                         xfree(reply[i].resp);
 411         }
 412         xfree(reply);
 413         buffer_free(&buffer);
 414         return (PAM_CONV_ERR);
 415 }
 416
 417 /*
 418  * Authentication thread.
 419  */
 420 static void *
 421 sshpam_thread(void *ctxtp)
 422 {
 423         struct pam_ctxt *ctxt = ctxtp;
 424         Buffer buffer;
 425         struct pam_conv sshpam_conv;
 426         int flags = (options.permit_empty_passwd == 0 ?
 427             PAM_DISALLOW_NULL_AUTHTOK : 0);
 428 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 429         extern char **environ;
 430         char **env_from_pam;
 431         u_int i;
 432         const char *pam_user;
 433         const char **ptr_pam_user = &pam_user;
 434
 435         pam_get_item(sshpam_handle, PAM_USER,
 436             (sshpam_const void **)ptr_pam_user);
 437         environ[0] = NULL;
 438
 439         if (sshpam_authctxt != NULL) {
 440                 setproctitle("%s [pam]",
 441                     sshpam_authctxt->valid ? pam_user : "unknown");
 442         }
 443 #endif
 444
 445         sshpam_conv.conv = sshpam_thread_conv;
 446         sshpam_conv.appdata_ptr = ctxt;
 447
 448         if (sshpam_authctxt == NULL)
 449                 fatal("%s: PAM authctxt not initialized", __func__);
 450
 451         buffer_init(&buffer);
 452         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 453             (const void *)&sshpam_conv);
 454         if (sshpam_err != PAM_SUCCESS)
 455                 goto auth_fail;
 456         sshpam_err = pam_authenticate(sshpam_handle, flags);
 457         if (sshpam_err != PAM_SUCCESS)
 458                 goto auth_fail;
 459
 460         if (compat20) {
 461                 if (!do_pam_account()) {
 462                         sshpam_err = PAM_ACCT_EXPIRED;
 463                         goto auth_fail;
 464                 }
 465                 if (sshpam_authctxt->force_pwchange) {
 466                         sshpam_err = pam_chauthtok(sshpam_handle,
 467                             PAM_CHANGE_EXPIRED_AUTHTOK);
 468                         if (sshpam_err != PAM_SUCCESS)
 469                                 goto auth_fail;
 470                         sshpam_password_change_required(0);
 471                 }
 472         }
 473
 474         buffer_put_cstring(&buffer, "OK");
 475
 476 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 477         /* Export variables set by do_pam_account */
 478         buffer_put_int(&buffer, sshpam_account_status);
 479         buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);
 480
 481         /* Export any environment strings set in child */
 482         for(i = 0; environ[i] != NULL; i++)
 483                 ; /* Count */
 484         buffer_put_int(&buffer, i);
 485         for(i = 0; environ[i] != NULL; i++)
 486                 buffer_put_cstring(&buffer, environ[i]);
 487
 488         /* Export any environment strings set by PAM in child */
 489         env_from_pam = pam_getenvlist(sshpam_handle);
 490         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 491                 ; /* Count */
 492         buffer_put_int(&buffer, i);
 493         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 494                 buffer_put_cstring(&buffer, env_from_pam[i]);
 495 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */
 496
 497         /* XXX - can't do much about an error here */
 498         ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
 499         buffer_free(&buffer);
 500         pthread_exit(NULL);
 501
 502  auth_fail:
 503         buffer_put_cstring(&buffer,
 504             pam_strerror(sshpam_handle, sshpam_err));
 505         /* XXX - can't do much about an error here */
 506         if (sshpam_err == PAM_ACCT_EXPIRED)
 507                 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, &buffer);
 508         else
 509                 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
 510         buffer_free(&buffer);
 511         pthread_exit(NULL);
 512
 513         return (NULL); /* Avoid warning for non-pthread case */
 514 }
 515
 516 void
 517 sshpam_thread_cleanup(void)
 518 {
 519         struct pam_ctxt *ctxt = cleanup_ctxt;
 520
 521         debug3("PAM: %s entering", __func__);
 522         if (ctxt != NULL && ctxt->pam_thread != 0) {
 523                 pthread_cancel(ctxt->pam_thread);
 524                 pthread_join(ctxt->pam_thread, NULL);
 525                 close(ctxt->pam_psock);
 526                 close(ctxt->pam_csock);
 527                 memset(ctxt, 0, sizeof(*ctxt));
 528                 cleanup_ctxt = NULL;
 529         }
 530 }
 531
 532 static int
 533 sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
 534     struct pam_response **resp, void *data)
 535 {
 536         debug3("PAM: %s entering, %d messages", __func__, n);
 537         return (PAM_CONV_ERR);
 538 }
 539
 540 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
 541
 542 static int
 543 sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
 544     struct pam_response **resp, void *data)
 545 {
 546         struct pam_response *reply;
 547         int i;
 548         size_t len;
 549
 550         debug3("PAM: %s called with %d messages", __func__, n);
 551         *resp = NULL;
 552
 553         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 554                 return (PAM_CONV_ERR);
 555
 556         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 557                 return (PAM_CONV_ERR);
 558
 559         for (i = 0; i < n; ++i) {
 560                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 561                 case PAM_ERROR_MSG:
 562                 case PAM_TEXT_INFO:
 563                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
 564                         buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
 565                         buffer_append(&loginmsg, "\n", 1 );
 566                         reply[i].resp_retcode = PAM_SUCCESS;
 567                         break;
 568                 default:
 569                         goto fail;
 570                 }
 571         }
 572         *resp = reply;
 573         return (PAM_SUCCESS);
 574
 575  fail:
 576         for(i = 0; i < n; i++) {
 577                 if (reply[i].resp != NULL)
 578                         xfree(reply[i].resp);
 579         }
 580         xfree(reply);
 581         return (PAM_CONV_ERR);
 582 }
 583
 584 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
 585
 586 void
 587 sshpam_cleanup(void)
 588 {
 589         debug("PAM: cleanup");
 590         if (sshpam_handle == NULL)
 591                 return;
 592         pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 593         if (sshpam_cred_established) {
 594                 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
 595                 sshpam_cred_established = 0;
 596         }
 597         if (sshpam_session_open) {
 598                 pam_close_session(sshpam_handle, PAM_SILENT);
 599                 sshpam_session_open = 0;
 600         }
 601         sshpam_authenticated = 0;
 602         pam_end(sshpam_handle, sshpam_err);
 603         sshpam_handle = NULL;
 604 }
 605
 606 static int
 607 sshpam_init(Authctxt *authctxt)
 608 {
 609         extern char *__progname;
 610         const char *pam_rhost, *pam_user, *user = authctxt->user;
 611         const char **ptr_pam_user = &pam_user;
 612
 613         if (sshpam_handle != NULL) {
 614                 /* We already have a PAM context; check if the user matches */
 615                 sshpam_err = pam_get_item(sshpam_handle,
 616                     PAM_USER, (sshpam_const void **)ptr_pam_user);
 617                 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
 618                         return (0);
 619                 pam_end(sshpam_handle, sshpam_err);
 620                 sshpam_handle = NULL;
 621         }
 622         debug("PAM: initializing for \"%s\"", user);
 623         sshpam_err =
 624             pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
 625         sshpam_authctxt = authctxt;
 626
 627         if (sshpam_err != PAM_SUCCESS) {
 628                 pam_end(sshpam_handle, sshpam_err);
 629                 sshpam_handle = NULL;
 630                 return (-1);
 631         }
 632         pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
 633         debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
 634         sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
 635         if (sshpam_err != PAM_SUCCESS) {
 636                 pam_end(sshpam_handle, sshpam_err);
 637                 sshpam_handle = NULL;
 638                 return (-1);
 639         }
 640 #ifdef PAM_TTY_KLUDGE
 641         /*
 642          * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
 643          * sshd doesn't set the tty until too late in the auth process and
 644          * may not even set one (for tty-less connections)
 645          */
 646         debug("PAM: setting PAM_TTY to \"ssh\"");
 647         sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
 648         if (sshpam_err != PAM_SUCCESS) {
 649                 pam_end(sshpam_handle, sshpam_err);
 650                 sshpam_handle = NULL;
 651                 return (-1);
 652         }
 653 #endif
 654         return (0);
 655 }
 656
 657 static void *
 658 sshpam_init_ctx(Authctxt *authctxt)
 659 {
 660         struct pam_ctxt *ctxt;
 661         int socks[2];
 662
 663         debug3("PAM: %s entering", __func__);
 664         /*
 665          * Refuse to start if we don't have PAM enabled or do_pam_account
 666          * has previously failed.
 667          */
 668         if (!options.use_pam || sshpam_account_status == 0)
 669                 return NULL;
 670
 671         /* Initialize PAM */
 672         if (sshpam_init(authctxt) == -1) {
 673                 error("PAM: initialization failed");
 674                 return (NULL);
 675         }
 676
 677         ctxt = xmalloc(sizeof *ctxt);
 678         memset(ctxt, 0, sizeof(*ctxt));
 679
 680         /* Start the authentication thread */
 681         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
 682                 error("PAM: failed create sockets: %s", strerror(errno));
 683                 xfree(ctxt);
 684                 return (NULL);
 685         }
 686         ctxt->pam_psock = socks[0];
 687         ctxt->pam_csock = socks[1];
 688         if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
 689                 error("PAM: failed to start authentication thread: %s",
 690                     strerror(errno));
 691                 close(socks[0]);
 692                 close(socks[1]);
 693                 xfree(ctxt);
 694                 return (NULL);
 695         }
 696         cleanup_ctxt = ctxt;
 697         return (ctxt);
 698 }
 699
 700 static int
 701 sshpam_query(void *ctx, char **name, char **info,
 702     u_int *num, char ***prompts, u_int **echo_on)
 703 {
 704         Buffer buffer;
 705         struct pam_ctxt *ctxt = ctx;
 706         size_t plen;
 707         u_char type;
 708         char *msg;
 709         size_t len, mlen;
 710
 711         debug3("PAM: %s entering", __func__);
 712         buffer_init(&buffer);
 713         *name = xstrdup("");
 714         *info = xstrdup("");
 715         *prompts = xmalloc(sizeof(char *));
 716         **prompts = NULL;
 717         plen = 0;
 718         *echo_on = xmalloc(sizeof(u_int));
 719         while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
 720                 type = buffer_get_char(&buffer);
 721                 msg = buffer_get_string(&buffer, NULL);
 722                 mlen = strlen(msg);
 723                 switch (type) {
 724                 case PAM_PROMPT_ECHO_ON:
 725                 case PAM_PROMPT_ECHO_OFF:
 726                         *num = 1;
 727                         len = plen + mlen + 1;
 728                         **prompts = xrealloc(**prompts, 1, len);
 729                         strlcpy(**prompts + plen, msg, len - plen);
 730                         plen += mlen;
 731                         **echo_on = (type == PAM_PROMPT_ECHO_ON);
 732                         xfree(msg);
 733                         return (0);
 734                 case PAM_ERROR_MSG:
 735                 case PAM_TEXT_INFO:
 736                         /* accumulate messages */
 737                         len = plen + mlen + 2;
 738                         **prompts = xrealloc(**prompts, 1, len);
 739                         strlcpy(**prompts + plen, msg, len - plen);
 740                         plen += mlen;
 741                         strlcat(**prompts + plen, "\n", len - plen);
 742                         plen++;
 743                         xfree(msg);
 744                         break;
 745                 case PAM_ACCT_EXPIRED:
 746                         sshpam_account_status = 0;
 747                         /* FALLTHROUGH */
 748                 case PAM_AUTH_ERR:
 749                         debug3("PAM: %s", pam_strerror(sshpam_handle, type));
 750                         if (**prompts != NULL && strlen(**prompts) != 0) {
 751                                 *info = **prompts;
 752                                 **prompts = NULL;
 753                                 *num = 0;
 754                                 **echo_on = 0;
 755                                 ctxt->pam_done = -1;
 756                                 xfree(msg);
 757                                 return 0;
 758                         }
 759                         /* FALLTHROUGH */
 760                 case PAM_SUCCESS:
 761                         if (**prompts != NULL) {
 762                                 /* drain any accumulated messages */
 763                                 debug("PAM: %s", **prompts);
 764                                 buffer_append(&loginmsg, **prompts,
 765                                     strlen(**prompts));
 766                                 xfree(**prompts);
 767                                 **prompts = NULL;
 768                         }
 769                         if (type == PAM_SUCCESS) {
 770                                 if (!sshpam_authctxt->valid ||
 771                                     (sshpam_authctxt->pw->pw_uid == 0 &&
 772                                     options.permit_root_login != PERMIT_YES))
 773                                         fatal("Internal error: PAM auth "
 774                                             "succeeded when it should have "
 775                                             "failed");
 776                                 import_environments(&buffer);
 777                                 *num = 0;
 778                                 **echo_on = 0;
 779                                 ctxt->pam_done = 1;
 780                                 xfree(msg);
 781                                 return (0);
 782                         }
 783                         error("PAM: %s for %s%.100s from %.100s", msg,
 784                             sshpam_authctxt->valid ? "" : "illegal user ",
 785                             sshpam_authctxt->user,
 786                             get_remote_name_or_ip(utmp_len, options.use_dns));
 787                         /* FALLTHROUGH */
 788                 default:
 789                         *num = 0;
 790                         **echo_on = 0;
 791                         xfree(msg);
 792                         ctxt->pam_done = -1;
 793                         return (-1);
 794                 }
 795         }
 796         return (-1);
 797 }
 798
 799 /* XXX - see also comment in auth-chall.c:verify_response */
 800 static int
 801 sshpam_respond(void *ctx, u_int num, char **resp)
 802 {
 803         Buffer buffer;
 804         struct pam_ctxt *ctxt = ctx;
 805
 806         debug2("PAM: %s entering, %u responses", __func__, num);
 807         switch (ctxt->pam_done) {
 808         case 1:
 809                 sshpam_authenticated = 1;
 810                 return (0);
 811         case 0:
 812                 break;
 813         default:
 814                 return (-1);
 815         }
 816         if (num != 1) {
 817                 error("PAM: expected one response, got %u", num);
 818                 return (-1);
 819         }
 820         buffer_init(&buffer);
 821         if (sshpam_authctxt->valid &&
 822             (sshpam_authctxt->pw->pw_uid != 0 ||
 823             options.permit_root_login == PERMIT_YES))
 824                 buffer_put_cstring(&buffer, *resp);
 825         else
 826                 buffer_put_cstring(&buffer, badpw);
 827         if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
 828                 buffer_free(&buffer);
 829                 return (-1);
 830         }
 831         buffer_free(&buffer);
 832         return (1);
 833 }
 834
 835 static void
 836 sshpam_free_ctx(void *ctxtp)
 837 {
 838         struct pam_ctxt *ctxt = ctxtp;
 839
 840         debug3("PAM: %s entering", __func__);
 841         sshpam_thread_cleanup();
 842         xfree(ctxt);
 843         /*
 844          * We don't call sshpam_cleanup() here because we may need the PAM
 845          * handle at a later stage, e.g. when setting up a session.  It's
 846          * still on the cleanup list, so pam_end() *will* be called before
 847          * the server process terminates.
 848          */
 849 }
 850
 851 KbdintDevice sshpam_device = {
 852         "pam",
 853         sshpam_init_ctx,
 854         sshpam_query,
 855         sshpam_respond,
 856         sshpam_free_ctx
 857 };
 858
 859 KbdintDevice mm_sshpam_device = {
 860         "pam",
 861         mm_sshpam_init_ctx,
 862         mm_sshpam_query,
 863         mm_sshpam_respond,
 864         mm_sshpam_free_ctx
 865 };
 866
 867 /*
 868  * This replaces auth-pam.c
 869  */
 870 void
 871 start_pam(Authctxt *authctxt)
 872 {
 873         if (!options.use_pam)
 874                 fatal("PAM: initialisation requested when UsePAM=no");
 875
 876         if (sshpam_init(authctxt) == -1)
 877                 fatal("PAM: initialisation failed");
 878 }
 879
 880 void
 881 finish_pam(void)
 882 {
 883         sshpam_cleanup();
 884 }
 885
 886 u_int
 887 do_pam_account(void)
 888 {
 889         debug("%s: called", __func__);
 890         if (sshpam_account_status != -1)
 891                 return (sshpam_account_status);
 892
 893         sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
 894         debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
 895             pam_strerror(sshpam_handle, sshpam_err));
 896
 897         if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
 898                 sshpam_account_status = 0;
 899                 return (sshpam_account_status);
 900         }
 901
 902         if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
 903                 sshpam_password_change_required(1);
 904
 905         sshpam_account_status = 1;
 906         return (sshpam_account_status);
 907 }
 908
 909 void
 910 do_pam_set_tty(const char *tty)
 911 {
 912         if (tty != NULL) {
 913                 debug("PAM: setting PAM_TTY to \"%s\"", tty);
 914                 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
 915                 if (sshpam_err != PAM_SUCCESS)
 916                         fatal("PAM: failed to set PAM_TTY: %s",
 917                             pam_strerror(sshpam_handle, sshpam_err));
 918         }
 919 }
 920
 921 void
 922 do_pam_setcred(int init)
 923 {
 924         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 925             (const void *)&store_conv);
 926         if (sshpam_err != PAM_SUCCESS)
 927                 fatal("PAM: failed to set PAM_CONV: %s",
 928                     pam_strerror(sshpam_handle, sshpam_err));
 929         if (init) {
 930                 debug("PAM: establishing credentials");
 931                 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
 932         } else {
 933                 debug("PAM: reinitializing credentials");
 934                 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
 935         }
 936         if (sshpam_err == PAM_SUCCESS) {
 937                 sshpam_cred_established = 1;
 938                 return;
 939         }
 940         if (sshpam_authenticated)
 941                 fatal("PAM: pam_setcred(): %s",
 942                     pam_strerror(sshpam_handle, sshpam_err));
 943         else
 944                 debug("PAM: pam_setcred(): %s",
 945                     pam_strerror(sshpam_handle, sshpam_err));
 946 }
 947
 948 static int
 949 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
 950     struct pam_response **resp, void *data)
 951 {
 952         char input[PAM_MAX_MSG_SIZE];
 953         struct pam_response *reply;
 954         int i;
 955
 956         debug3("PAM: %s called with %d messages", __func__, n);
 957
 958         *resp = NULL;
 959
 960         if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
 961                 return (PAM_CONV_ERR);
 962
 963         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 964                 return (PAM_CONV_ERR);
 965
 966         for (i = 0; i < n; ++i) {
 967                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 968                 case PAM_PROMPT_ECHO_OFF:
 969                         reply[i].resp =
 970                             read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
 971                             RP_ALLOW_STDIN);
 972                         reply[i].resp_retcode = PAM_SUCCESS;
 973                         break;
 974                 case PAM_PROMPT_ECHO_ON:
 975                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 976                         fgets(input, sizeof input, stdin);
 977                         if ((reply[i].resp = strdup(input)) == NULL)
 978                                 goto fail;
 979                         reply[i].resp_retcode = PAM_SUCCESS;
 980                         break;
 981                 case PAM_ERROR_MSG:
 982                 case PAM_TEXT_INFO:
 983                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 984                         reply[i].resp_retcode = PAM_SUCCESS;
 985                         break;
 986                 default:
 987                         goto fail;
 988                 }
 989         }
 990         *resp = reply;
 991         return (PAM_SUCCESS);
 992
 993  fail:
 994         for(i = 0; i < n; i++) {
 995                 if (reply[i].resp != NULL)
 996                         xfree(reply[i].resp);
 997         }
 998         xfree(reply);
 999         return (PAM_CONV_ERR);
1000 }
1001
1002 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
1003
1004 /*
1005  * XXX this should be done in the authentication phase, but ssh1 doesn't
1006  * support that
1007  */
1008 void
1009 do_pam_chauthtok(void)
1010 {
1011         if (use_privsep)
1012                 fatal("Password expired (unable to change with privsep)");
1013         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1014             (const void *)&tty_conv);
1015         if (sshpam_err != PAM_SUCCESS)
1016                 fatal("PAM: failed to set PAM_CONV: %s",
1017                     pam_strerror(sshpam_handle, sshpam_err));
1018         debug("PAM: changing password");
1019         sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
1020         if (sshpam_err != PAM_SUCCESS)
1021                 fatal("PAM: pam_chauthtok(): %s",
1022                     pam_strerror(sshpam_handle, sshpam_err));
1023 }
1024
1025 void
1026 do_pam_session(void)
1027 {
1028         debug3("PAM: opening session");
1029         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1030             (const void *)&store_conv);
1031         if (sshpam_err != PAM_SUCCESS)
1032                 fatal("PAM: failed to set PAM_CONV: %s",
1033                     pam_strerror(sshpam_handle, sshpam_err));
1034         sshpam_err = pam_open_session(sshpam_handle, 0);
1035         if (sshpam_err == PAM_SUCCESS)
1036                 sshpam_session_open = 1;
1037         else {
1038                 sshpam_session_open = 0;
1039                 disable_forwarding();
1040                 error("PAM: pam_open_session(): %s",
1041                     pam_strerror(sshpam_handle, sshpam_err));
1042         }
1043
1044 }
1045
1046 int
1047 is_pam_session_open(void)
1048 {
1049         return sshpam_session_open;
1050 }
1051
1052 /*
1053  * Set a PAM environment string. We need to do this so that the session
1054  * modules can handle things like Kerberos/GSI credentials that appear
1055  * during the ssh authentication process.
1056  */
1057 int
1058 do_pam_putenv(char *name, char *value)
1059 {
1060         int ret = 1;
1061 #ifdef HAVE_PAM_PUTENV
1062         char *compound;
1063         size_t len;
1064
1065         len = strlen(name) + strlen(value) + 2;
1066         compound = xmalloc(len);
1067
1068         snprintf(compound, len, "%s=%s", name, value);
1069         ret = pam_putenv(sshpam_handle, compound);
1070         xfree(compound);
1071 #endif
1072
1073         return (ret);
1074 }
1075
1076 char **
1077 fetch_pam_child_environment(void)
1078 {
1079         return sshpam_env;
1080 }
1081
1082 char **
1083 fetch_pam_environment(void)
1084 {
1085         return (pam_getenvlist(sshpam_handle));
1086 }
1087
1088 void
1089 free_pam_environment(char **env)
1090 {
1091         char **envp;
1092
1093         if (env == NULL)
1094                 return;
1095
1096         for (envp = env; *envp; envp++)
1097                 xfree(*envp);
1098         xfree(env);
1099 }
1100
1101 /*
1102  * "Blind" conversation function for password authentication.  Assumes that
1103  * echo-off prompts are for the password and stores messages for later
1104  * display.
1105  */
1106 static int
1107 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1108     struct pam_response **resp, void *data)
1109 {
1110         struct pam_response *reply;
1111         int i;
1112         size_t len;
1113
1114         debug3("PAM: %s called with %d messages", __func__, n);
1115
1116         *resp = NULL;
1117
1118         if (n <= 0 || n > PAM_MAX_NUM_MSG)
1119                 return (PAM_CONV_ERR);
1120
1121         if ((reply = malloc(n * sizeof(*reply))) == NULL)
1122                 return (PAM_CONV_ERR);
1123         memset(reply, 0, n * sizeof(*reply));
1124
1125         for (i = 0; i < n; ++i) {
1126                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1127                 case PAM_PROMPT_ECHO_OFF:
1128                         if (sshpam_password == NULL)
1129                                 goto fail;
1130                         if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1131                                 goto fail;
1132                         reply[i].resp_retcode = PAM_SUCCESS;
1133                         break;
1134                 case PAM_ERROR_MSG:
1135                 case PAM_TEXT_INFO:
1136                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1137                         if (len > 0) {
1138                                 buffer_append(&loginmsg,
1139                                     PAM_MSG_MEMBER(msg, i, msg), len);
1140                                 buffer_append(&loginmsg, "\n", 1);
1141                         }
1142                         if ((reply[i].resp = strdup("")) == NULL)
1143                                 goto fail;
1144                         reply[i].resp_retcode = PAM_SUCCESS;
1145                         break;
1146                 default:
1147                         goto fail;
1148                 }
1149         }
1150         *resp = reply;
1151         return (PAM_SUCCESS);
1152
1153  fail:
1154         for(i = 0; i < n; i++) {
1155                 if (reply[i].resp != NULL)
1156                         xfree(reply[i].resp);
1157         }
1158         xfree(reply);
1159         return (PAM_CONV_ERR);
1160 }
1161
1162 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1163
1164 /*
1165  * Attempt password authentication via PAM
1166  */
1167 int
1168 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1169 {
1170         int flags = (options.permit_empty_passwd == 0 ?
1171             PAM_DISALLOW_NULL_AUTHTOK : 0);
1172
1173         if (!options.use_pam || sshpam_handle == NULL)
1174                 fatal("PAM: %s called when PAM disabled or failed to "
1175                     "initialise.", __func__);
1176
1177         sshpam_password = password;
1178         sshpam_authctxt = authctxt;
1179
1180         /*
1181          * If the user logging in is invalid, or is root but is not permitted
1182          * by PermitRootLogin, use an invalid password to prevent leaking
1183          * information via timing (eg if the PAM config has a delay on fail).
1184          */
1185         if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1186             options.permit_root_login != PERMIT_YES))
1187                 sshpam_password = badpw;
1188
1189         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1190             (const void *)&passwd_conv);
1191         if (sshpam_err != PAM_SUCCESS)
1192                 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1193                     pam_strerror(sshpam_handle, sshpam_err));
1194
1195         sshpam_err = pam_authenticate(sshpam_handle, flags);
1196         sshpam_password = NULL;
1197         if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1198                 debug("PAM: password authentication accepted for %.100s",
1199                     authctxt->user);
1200                 return 1;
1201         } else {
1202                 debug("PAM: password authentication failed for %.100s: %s",
1203                     authctxt->valid ? authctxt->user : "an illegal user",
1204                     pam_strerror(sshpam_handle, sshpam_err));
1205                 return 0;
1206         }
1207 }
1208 #endif /* USE_PAM */