crypto/openssh-4/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: auth-pam.c,v 1.128 2006/01/29 05:46:13 dtucker Exp $");
  51
  52 #ifdef USE_PAM
  53 #if defined(HAVE_SECURITY_PAM_APPL_H)
  54 #include <security/pam_appl.h>
  55 #elif defined (HAVE_PAM_PAM_APPL_H)
  56 #include <pam/pam_appl.h>
  57 #endif
  58
  59 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */
  60 #ifdef PAM_SUN_CODEBASE
  61 # define sshpam_const           /* Solaris, HP-UX, AIX */
  62 #else
  63 # define sshpam_const   const   /* LinuxPAM, OpenPAM */
  64 #endif
  65
  66 #include "auth.h"
  67 #include "auth-pam.h"
  68 #include "buffer.h"
  69 #include "bufaux.h"
  70 #include "canohost.h"
  71 #include "log.h"
  72 #include "monitor_wrap.h"
  73 #include "msg.h"
  74 #include "packet.h"
  75 #include "misc.h"
  76 #include "servconf.h"
  77 #include "ssh2.h"
  78 #include "xmalloc.h"
  79 #include "auth-options.h"
  80
  81 extern ServerOptions options;
  82 extern Buffer loginmsg;
  83 extern int compat20;
  84 extern u_int utmp_len;
  85
  86 /* so we don't silently change behaviour */
  87 #ifdef USE_POSIX_THREADS
  88 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
  89 #endif
  90
  91 /*
  92  * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
  93  * and generally a bad idea.  Use at own risk and do not expect support if
  94  * this breaks.
  95  */
  96 #ifdef UNSUPPORTED_POSIX_THREADS_HACK
  97 #include <pthread.h>
  98 /*
  99  * Avoid namespace clash when *not* using pthreads for systems *with*
 100  * pthreads, which unconditionally define pthread_t via sys/types.h
 101  * (e.g. Linux)
 102  */
 103 typedef pthread_t sp_pthread_t;
 104 #else
 105 typedef pid_t sp_pthread_t;
 106 #endif
 107
 108 struct pam_ctxt {
 109         sp_pthread_t     pam_thread;
 110         int              pam_psock;
 111         int              pam_csock;
 112         int              pam_done;
 113 };
 114
 115 static void sshpam_free_ctx(void *);
 116 static struct pam_ctxt *cleanup_ctxt;
 117
 118 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 119 /*
 120  * Simulate threads with processes.
 121  */
 122
 123 static int sshpam_thread_status = -1;
 124 static mysig_t sshpam_oldsig;
 125
 126 static void
 127 sshpam_sigchld_handler(int sig)
 128 {
 129         signal(SIGCHLD, SIG_DFL);
 130         if (cleanup_ctxt == NULL)
 131                 return; /* handler called after PAM cleanup, shouldn't happen */
 132         if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
 133             <= 0) {
 134                 /* PAM thread has not exitted, privsep slave must have */
 135                 kill(cleanup_ctxt->pam_thread, SIGTERM);
 136                 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0)
 137                     <= 0)
 138                         return; /* could not wait */
 139         }
 140         if (WIFSIGNALED(sshpam_thread_status) &&
 141             WTERMSIG(sshpam_thread_status) == SIGTERM)
 142                 return; /* terminated by pthread_cancel */
 143         if (!WIFEXITED(sshpam_thread_status))
 144                 fatal("PAM: authentication thread exited unexpectedly");
 145         if (WEXITSTATUS(sshpam_thread_status) != 0)
 146                 fatal("PAM: authentication thread exited uncleanly");
 147 }
 148
 149 static void
 150 pthread_exit(void *value __unused)
 151 {
 152         _exit(0);
 153 }
 154
 155 static int
 156 pthread_create(sp_pthread_t *thread, const void *attr __unused,
 157     void *(*thread_start)(void *), void *arg)
 158 {
 159         pid_t pid;
 160         struct pam_ctxt *ctx = arg;
 161
 162         sshpam_thread_status = -1;
 163         switch ((pid = fork())) {
 164         case -1:
 165                 error("fork(): %s", strerror(errno));
 166                 return (-1);
 167         case 0:
 168                 close(ctx->pam_psock);
 169                 ctx->pam_psock = -1;
 170                 thread_start(arg);
 171                 _exit(1);
 172         default:
 173                 *thread = pid;
 174                 close(ctx->pam_csock);
 175                 ctx->pam_csock = -1;
 176                 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
 177                 return (0);
 178         }
 179 }
 180
 181 static int
 182 pthread_cancel(sp_pthread_t thread)
 183 {
 184         signal(SIGCHLD, sshpam_oldsig);
 185         return (kill(thread, SIGTERM));
 186 }
 187
 188 static int
 189 pthread_join(sp_pthread_t thread, void **value __unused)
 190 {
 191         int status;
 192
 193         if (sshpam_thread_status != -1)
 194                 return (sshpam_thread_status);
 195         signal(SIGCHLD, sshpam_oldsig);
 196         waitpid(thread, &status, 0);
 197         return (status);
 198 }
 199 #endif
 200
 201
 202 static pam_handle_t *sshpam_handle = NULL;
 203 static int sshpam_err = 0;
 204 static int sshpam_authenticated = 0;
 205 static int sshpam_session_open = 0;
 206 static int sshpam_cred_established = 0;
 207 static int sshpam_account_status = -1;
 208 static char **sshpam_env = NULL;
 209 static Authctxt *sshpam_authctxt = NULL;
 210 static const char *sshpam_password = NULL;
 211 static char badpw[] = "\b\n\r\177INCORRECT";
 212
 213 /* Some PAM implementations don't implement this */
 214 #ifndef HAVE_PAM_GETENVLIST
 215 static char **
 216 pam_getenvlist(pam_handle_t *pamh)
 217 {
 218         /*
 219          * XXX - If necessary, we can still support envrionment passing
 220          * for platforms without pam_getenvlist by searching for known
 221          * env vars (e.g. KRB5CCNAME) from the PAM environment.
 222          */
 223          return NULL;
 224 }
 225 #endif
 226
 227 /*
 228  * Some platforms, notably Solaris, do not enforce password complexity
 229  * rules during pam_chauthtok() if the real uid of the calling process
 230  * is 0, on the assumption that it's being called by "passwd" run by root.
 231  * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
 232  * the right thing.
 233  */
 234 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
 235 static int
 236 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
 237 {
 238         int result;
 239
 240         if (sshpam_authctxt == NULL)
 241                 fatal("PAM: sshpam_authctxt not initialized");
 242         if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
 243                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 244         result = pam_chauthtok(pamh, flags);
 245         if (setreuid(0, -1) == -1)
 246                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 247         return result;
 248 }
 249 # define pam_chauthtok(a,b)     (sshpam_chauthtok_ruid((a), (b)))
 250 #endif
 251
 252 void
 253 sshpam_password_change_required(int reqd)
 254 {
 255         debug3("%s %d", __func__, reqd);
 256         if (sshpam_authctxt == NULL)
 257                 fatal("%s: PAM authctxt not initialized", __func__);
 258         sshpam_authctxt->force_pwchange = reqd;
 259         if (reqd) {
 260                 no_port_forwarding_flag |= 2;
 261                 no_agent_forwarding_flag |= 2;
 262                 no_x11_forwarding_flag |= 2;
 263         } else {
 264                 no_port_forwarding_flag &= ~2;
 265                 no_agent_forwarding_flag &= ~2;
 266                 no_x11_forwarding_flag &= ~2;
 267         }
 268 }
 269
 270 /* Import regular and PAM environment from subprocess */
 271 static void
 272 import_environments(Buffer *b)
 273 {
 274         char *env;
 275         u_int i, num_env;
 276         int err;
 277
 278         debug3("PAM: %s entering", __func__);
 279
 280 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 281         /* Import variables set by do_pam_account */
 282         sshpam_account_status = buffer_get_int(b);
 283         sshpam_password_change_required(buffer_get_int(b));
 284
 285         /* Import environment from subprocess */
 286         num_env = buffer_get_int(b);
 287         sshpam_env = xmalloc((num_env + 1) * sizeof(*sshpam_env));
 288         debug3("PAM: num env strings %d", num_env);
 289         for(i = 0; i < num_env; i++)
 290                 sshpam_env[i] = buffer_get_string(b, NULL);
 291
 292         sshpam_env[num_env] = NULL;
 293
 294         /* Import PAM environment from subprocess */
 295         num_env = buffer_get_int(b);
 296         debug("PAM: num PAM env strings %d", num_env);
 297         for(i = 0; i < num_env; i++) {
 298                 env = buffer_get_string(b, NULL);
 299
 300 #ifdef HAVE_PAM_PUTENV
 301                 /* Errors are not fatal here */
 302                 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
 303                         error("PAM: pam_putenv: %s",
 304                             pam_strerror(sshpam_handle, sshpam_err));
 305                 }
 306 #endif
 307         }
 308 #endif
 309 }
 310
 311 /*
 312  * Conversation function for authentication thread.
 313  */
 314 static int
 315 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
 316     struct pam_response **resp, void *data)
 317 {
 318         Buffer buffer;
 319         struct pam_ctxt *ctxt;
 320         struct pam_response *reply;
 321         int i;
 322
 323         debug3("PAM: %s entering, %d messages", __func__, n);
 324         *resp = NULL;
 325
 326         if (data == NULL) {
 327                 error("PAM: conversation function passed a null context");
 328                 return (PAM_CONV_ERR);
 329         }
 330         ctxt = data;
 331         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 332                 return (PAM_CONV_ERR);
 333
 334         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 335                 return (PAM_CONV_ERR);
 336         memset(reply, 0, n * sizeof(*reply));
 337
 338         buffer_init(&buffer);
 339         for (i = 0; i < n; ++i) {
 340                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 341                 case PAM_PROMPT_ECHO_OFF:
 342                         buffer_put_cstring(&buffer,
 343                             PAM_MSG_MEMBER(msg, i, msg));
 344                         if (ssh_msg_send(ctxt->pam_csock,
 345                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 346                                 goto fail;
 347                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 348                                 goto fail;
 349                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 350                                 goto fail;
 351                         reply[i].resp = buffer_get_string(&buffer, NULL);
 352                         break;
 353                 case PAM_PROMPT_ECHO_ON:
 354                         buffer_put_cstring(&buffer,
 355                             PAM_MSG_MEMBER(msg, i, msg));
 356                         if (ssh_msg_send(ctxt->pam_csock,
 357                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 358                                 goto fail;
 359                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 360                                 goto fail;
 361                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 362                                 goto fail;
 363                         reply[i].resp = buffer_get_string(&buffer, NULL);
 364                         break;
 365                 case PAM_ERROR_MSG:
 366                         buffer_put_cstring(&buffer,
 367                             PAM_MSG_MEMBER(msg, i, msg));
 368                         if (ssh_msg_send(ctxt->pam_csock,
 369                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 370                                 goto fail;
 371                         break;
 372                 case PAM_TEXT_INFO:
 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                         break;
 379                 default:
 380                         goto fail;
 381                 }
 382                 buffer_clear(&buffer);
 383         }
 384         buffer_free(&buffer);
 385         *resp = reply;
 386         return (PAM_SUCCESS);
 387
 388  fail:
 389         for(i = 0; i < n; i++) {
 390                 if (reply[i].resp != NULL)
 391                         xfree(reply[i].resp);
 392         }
 393         xfree(reply);
 394         buffer_free(&buffer);
 395         return (PAM_CONV_ERR);
 396 }
 397
 398 /*
 399  * Authentication thread.
 400  */
 401 static void *
 402 sshpam_thread(void *ctxtp)
 403 {
 404         struct pam_ctxt *ctxt = ctxtp;
 405         Buffer buffer;
 406         struct pam_conv sshpam_conv;
 407         int flags = (options.permit_empty_passwd == 0 ?
 408             PAM_DISALLOW_NULL_AUTHTOK : 0);
 409 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 410         extern char **environ;
 411         char **env_from_pam;
 412         u_int i;
 413         const char *pam_user;
 414         const char **ptr_pam_user = &pam_user;
 415
 416         pam_get_item(sshpam_handle, PAM_USER,
 417             (sshpam_const void **)ptr_pam_user);
 418         environ[0] = NULL;
 419
 420         if (sshpam_authctxt != NULL) {
 421                 setproctitle("%s [pam]",
 422                     sshpam_authctxt->valid ? pam_user : "unknown");
 423         }
 424 #endif
 425
 426         sshpam_conv.conv = sshpam_thread_conv;
 427         sshpam_conv.appdata_ptr = ctxt;
 428
 429         if (sshpam_authctxt == NULL)
 430                 fatal("%s: PAM authctxt not initialized", __func__);
 431
 432         buffer_init(&buffer);
 433         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 434             (const void *)&sshpam_conv);
 435         if (sshpam_err != PAM_SUCCESS)
 436                 goto auth_fail;
 437         sshpam_err = pam_authenticate(sshpam_handle, flags);
 438         if (sshpam_err != PAM_SUCCESS)
 439                 goto auth_fail;
 440
 441         if (compat20) {
 442                 if (!do_pam_account())
 443                         goto auth_fail;
 444                 if (sshpam_authctxt->force_pwchange) {
 445                         sshpam_err = pam_chauthtok(sshpam_handle,
 446                             PAM_CHANGE_EXPIRED_AUTHTOK);
 447                         if (sshpam_err != PAM_SUCCESS)
 448                                 goto auth_fail;
 449                         sshpam_password_change_required(0);
 450                 }
 451         }
 452
 453         buffer_put_cstring(&buffer, "OK");
 454
 455 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 456         /* Export variables set by do_pam_account */
 457         buffer_put_int(&buffer, sshpam_account_status);
 458         buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);
 459
 460         /* Export any environment strings set in child */
 461         for(i = 0; environ[i] != NULL; i++)
 462                 ; /* Count */
 463         buffer_put_int(&buffer, i);
 464         for(i = 0; environ[i] != NULL; i++)
 465                 buffer_put_cstring(&buffer, environ[i]);
 466
 467         /* Export any environment strings set by PAM in child */
 468         env_from_pam = pam_getenvlist(sshpam_handle);
 469         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 470                 ; /* Count */
 471         buffer_put_int(&buffer, i);
 472         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 473                 buffer_put_cstring(&buffer, env_from_pam[i]);
 474 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */
 475
 476         /* XXX - can't do much about an error here */
 477         ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
 478         buffer_free(&buffer);
 479         pthread_exit(NULL);
 480
 481  auth_fail:
 482         buffer_put_cstring(&buffer,
 483             pam_strerror(sshpam_handle, sshpam_err));
 484         /* XXX - can't do much about an error here */
 485         ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
 486         buffer_free(&buffer);
 487         pthread_exit(NULL);
 488
 489         return (NULL); /* Avoid warning for non-pthread case */
 490 }
 491
 492 void
 493 sshpam_thread_cleanup(void)
 494 {
 495         struct pam_ctxt *ctxt = cleanup_ctxt;
 496
 497         debug3("PAM: %s entering", __func__);
 498         if (ctxt != NULL && ctxt->pam_thread != 0) {
 499                 pthread_cancel(ctxt->pam_thread);
 500                 pthread_join(ctxt->pam_thread, NULL);
 501                 close(ctxt->pam_psock);
 502                 close(ctxt->pam_csock);
 503                 memset(ctxt, 0, sizeof(*ctxt));
 504                 cleanup_ctxt = NULL;
 505         }
 506 }
 507
 508 static int
 509 sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
 510     struct pam_response **resp, void *data)
 511 {
 512         debug3("PAM: %s entering, %d messages", __func__, n);
 513         return (PAM_CONV_ERR);
 514 }
 515
 516 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
 517
 518 static int
 519 sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
 520     struct pam_response **resp, void *data)
 521 {
 522         struct pam_response *reply;
 523         int i;
 524         size_t len;
 525
 526         debug3("PAM: %s called with %d messages", __func__, n);
 527         *resp = NULL;
 528
 529         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 530                 return (PAM_CONV_ERR);
 531
 532         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 533                 return (PAM_CONV_ERR);
 534         memset(reply, 0, n * sizeof(*reply));
 535
 536         for (i = 0; i < n; ++i) {
 537                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 538                 case PAM_ERROR_MSG:
 539                 case PAM_TEXT_INFO:
 540                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
 541                         buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
 542                         buffer_append(&loginmsg, "\n", 1 );
 543                         reply[i].resp_retcode = PAM_SUCCESS;
 544                         break;
 545                 default:
 546                         goto fail;
 547                 }
 548         }
 549         *resp = reply;
 550         return (PAM_SUCCESS);
 551
 552  fail:
 553         for(i = 0; i < n; i++) {
 554                 if (reply[i].resp != NULL)
 555                         xfree(reply[i].resp);
 556         }
 557         xfree(reply);
 558         return (PAM_CONV_ERR);
 559 }
 560
 561 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
 562
 563 void
 564 sshpam_cleanup(void)
 565 {
 566         debug("PAM: cleanup");
 567         if (sshpam_handle == NULL)
 568                 return;
 569         pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 570         if (sshpam_cred_established) {
 571                 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
 572                 sshpam_cred_established = 0;
 573         }
 574         if (sshpam_session_open) {
 575                 pam_close_session(sshpam_handle, PAM_SILENT);
 576                 sshpam_session_open = 0;
 577         }
 578         sshpam_authenticated = 0;
 579         pam_end(sshpam_handle, sshpam_err);
 580         sshpam_handle = NULL;
 581 }
 582
 583 static int
 584 sshpam_init(Authctxt *authctxt)
 585 {
 586         extern char *__progname;
 587         const char *pam_rhost, *pam_user, *user = authctxt->user;
 588         const char **ptr_pam_user = &pam_user;
 589
 590         if (sshpam_handle != NULL) {
 591                 /* We already have a PAM context; check if the user matches */
 592                 sshpam_err = pam_get_item(sshpam_handle,
 593                     PAM_USER, (sshpam_const void **)ptr_pam_user);
 594                 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
 595                         return (0);
 596                 pam_end(sshpam_handle, sshpam_err);
 597                 sshpam_handle = NULL;
 598         }
 599         debug("PAM: initializing for \"%s\"", user);
 600         sshpam_err =
 601             pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
 602         sshpam_authctxt = authctxt;
 603
 604         if (sshpam_err != PAM_SUCCESS) {
 605                 pam_end(sshpam_handle, sshpam_err);
 606                 sshpam_handle = NULL;
 607                 return (-1);
 608         }
 609         pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
 610         debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
 611         sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
 612         if (sshpam_err != PAM_SUCCESS) {
 613                 pam_end(sshpam_handle, sshpam_err);
 614                 sshpam_handle = NULL;
 615                 return (-1);
 616         }
 617 #ifdef PAM_TTY_KLUDGE
 618         /*
 619          * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
 620          * sshd doesn't set the tty until too late in the auth process and
 621          * may not even set one (for tty-less connections)
 622          */
 623         debug("PAM: setting PAM_TTY to \"ssh\"");
 624         sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
 625         if (sshpam_err != PAM_SUCCESS) {
 626                 pam_end(sshpam_handle, sshpam_err);
 627                 sshpam_handle = NULL;
 628                 return (-1);
 629         }
 630 #endif
 631         return (0);
 632 }
 633
 634 static void *
 635 sshpam_init_ctx(Authctxt *authctxt)
 636 {
 637         struct pam_ctxt *ctxt;
 638         int socks[2];
 639
 640         debug3("PAM: %s entering", __func__);
 641         /* Refuse to start if we don't have PAM enabled */
 642         if (!options.use_pam)
 643                 return NULL;
 644
 645         /* Initialize PAM */
 646         if (sshpam_init(authctxt) == -1) {
 647                 error("PAM: initialization failed");
 648                 return (NULL);
 649         }
 650
 651         ctxt = xmalloc(sizeof *ctxt);
 652         memset(ctxt, 0, sizeof(*ctxt));
 653
 654         /* Start the authentication thread */
 655         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
 656                 error("PAM: failed create sockets: %s", strerror(errno));
 657                 xfree(ctxt);
 658                 return (NULL);
 659         }
 660         ctxt->pam_psock = socks[0];
 661         ctxt->pam_csock = socks[1];
 662         if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
 663                 error("PAM: failed to start authentication thread: %s",
 664                     strerror(errno));
 665                 close(socks[0]);
 666                 close(socks[1]);
 667                 xfree(ctxt);
 668                 return (NULL);
 669         }
 670         cleanup_ctxt = ctxt;
 671         return (ctxt);
 672 }
 673
 674 static int
 675 sshpam_query(void *ctx, char **name, char **info,
 676     u_int *num, char ***prompts, u_int **echo_on)
 677 {
 678         Buffer buffer;
 679         struct pam_ctxt *ctxt = ctx;
 680         size_t plen;
 681         u_char type;
 682         char *msg;
 683         size_t len, mlen;
 684
 685         debug3("PAM: %s entering", __func__);
 686         buffer_init(&buffer);
 687         *name = xstrdup("");
 688         *info = xstrdup("");
 689         *prompts = xmalloc(sizeof(char *));
 690         **prompts = NULL;
 691         plen = 0;
 692         *echo_on = xmalloc(sizeof(u_int));
 693         while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
 694                 type = buffer_get_char(&buffer);
 695                 msg = buffer_get_string(&buffer, NULL);
 696                 mlen = strlen(msg);
 697                 switch (type) {
 698                 case PAM_PROMPT_ECHO_ON:
 699                 case PAM_PROMPT_ECHO_OFF:
 700                         *num = 1;
 701                         len = plen + mlen + 1;
 702                         **prompts = xrealloc(**prompts, len);
 703                         strlcpy(**prompts + plen, msg, len - plen);
 704                         plen += mlen;
 705                         **echo_on = (type == PAM_PROMPT_ECHO_ON);
 706                         xfree(msg);
 707                         return (0);
 708                 case PAM_ERROR_MSG:
 709                 case PAM_TEXT_INFO:
 710                         /* accumulate messages */
 711                         len = plen + mlen + 2;
 712                         **prompts = xrealloc(**prompts, len);
 713                         strlcpy(**prompts + plen, msg, len - plen);
 714                         plen += mlen;
 715                         strlcat(**prompts + plen, "\n", len - plen);
 716                         plen++;
 717                         xfree(msg);
 718                         break;
 719                 case PAM_AUTH_ERR:
 720                         debug3("PAM: PAM_AUTH_ERR");
 721                         if (**prompts != NULL && strlen(**prompts) != 0) {
 722                                 *info = **prompts;
 723                                 **prompts = NULL;
 724                                 *num = 0;
 725                                 **echo_on = 0;
 726                                 ctxt->pam_done = -1;
 727                                 return 0;
 728                         }
 729                         /* FALLTHROUGH */
 730                 case PAM_SUCCESS:
 731                         if (**prompts != NULL) {
 732                                 /* drain any accumulated messages */
 733                                 debug("PAM: %s", **prompts);
 734                                 buffer_append(&loginmsg, **prompts,
 735                                     strlen(**prompts));
 736                                 xfree(**prompts);
 737                                 **prompts = NULL;
 738                         }
 739                         if (type == PAM_SUCCESS) {
 740                                 if (!sshpam_authctxt->valid ||
 741                                     (sshpam_authctxt->pw->pw_uid == 0 &&
 742                                     options.permit_root_login != PERMIT_YES))
 743                                         fatal("Internal error: PAM auth "
 744                                             "succeeded when it should have "
 745                                             "failed");
 746                                 import_environments(&buffer);
 747                                 *num = 0;
 748                                 **echo_on = 0;
 749                                 ctxt->pam_done = 1;
 750                                 xfree(msg);
 751                                 return (0);
 752                         }
 753                         error("PAM: %s for %s%.100s from %.100s", msg,
 754                             sshpam_authctxt->valid ? "" : "illegal user ",
 755                             sshpam_authctxt->user,
 756                             get_remote_name_or_ip(utmp_len, options.use_dns));
 757                         /* FALLTHROUGH */
 758                 default:
 759                         *num = 0;
 760                         **echo_on = 0;
 761                         xfree(msg);
 762                         ctxt->pam_done = -1;
 763                         return (-1);
 764                 }
 765         }
 766         return (-1);
 767 }
 768
 769 /* XXX - see also comment in auth-chall.c:verify_response */
 770 static int
 771 sshpam_respond(void *ctx, u_int num, char **resp)
 772 {
 773         Buffer buffer;
 774         struct pam_ctxt *ctxt = ctx;
 775
 776         debug2("PAM: %s entering, %u responses", __func__, num);
 777         switch (ctxt->pam_done) {
 778         case 1:
 779                 sshpam_authenticated = 1;
 780                 return (0);
 781         case 0:
 782                 break;
 783         default:
 784                 return (-1);
 785         }
 786         if (num != 1) {
 787                 error("PAM: expected one response, got %u", num);
 788                 return (-1);
 789         }
 790         buffer_init(&buffer);
 791         if (sshpam_authctxt->valid &&
 792             (sshpam_authctxt->pw->pw_uid != 0 ||
 793             options.permit_root_login == PERMIT_YES))
 794                 buffer_put_cstring(&buffer, *resp);
 795         else
 796                 buffer_put_cstring(&buffer, badpw);
 797         if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
 798                 buffer_free(&buffer);
 799                 return (-1);
 800         }
 801         buffer_free(&buffer);
 802         return (1);
 803 }
 804
 805 static void
 806 sshpam_free_ctx(void *ctxtp)
 807 {
 808         struct pam_ctxt *ctxt = ctxtp;
 809
 810         debug3("PAM: %s entering", __func__);
 811         sshpam_thread_cleanup();
 812         xfree(ctxt);
 813         /*
 814          * We don't call sshpam_cleanup() here because we may need the PAM
 815          * handle at a later stage, e.g. when setting up a session.  It's
 816          * still on the cleanup list, so pam_end() *will* be called before
 817          * the server process terminates.
 818          */
 819 }
 820
 821 KbdintDevice sshpam_device = {
 822         "pam",
 823         sshpam_init_ctx,
 824         sshpam_query,
 825         sshpam_respond,
 826         sshpam_free_ctx
 827 };
 828
 829 KbdintDevice mm_sshpam_device = {
 830         "pam",
 831         mm_sshpam_init_ctx,
 832         mm_sshpam_query,
 833         mm_sshpam_respond,
 834         mm_sshpam_free_ctx
 835 };
 836
 837 /*
 838  * This replaces auth-pam.c
 839  */
 840 void
 841 start_pam(Authctxt *authctxt)
 842 {
 843         if (!options.use_pam)
 844                 fatal("PAM: initialisation requested when UsePAM=no");
 845
 846         if (sshpam_init(authctxt) == -1)
 847                 fatal("PAM: initialisation failed");
 848 }
 849
 850 void
 851 finish_pam(void)
 852 {
 853         sshpam_cleanup();
 854 }
 855
 856 u_int
 857 do_pam_account(void)
 858 {
 859         debug("%s: called", __func__);
 860         if (sshpam_account_status != -1)
 861                 return (sshpam_account_status);
 862
 863         sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
 864         debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
 865             pam_strerror(sshpam_handle, sshpam_err));
 866
 867         if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
 868                 sshpam_account_status = 0;
 869                 return (sshpam_account_status);
 870         }
 871
 872         if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
 873                 sshpam_password_change_required(1);
 874
 875         sshpam_account_status = 1;
 876         return (sshpam_account_status);
 877 }
 878
 879 void
 880 do_pam_set_tty(const char *tty)
 881 {
 882         if (tty != NULL) {
 883                 debug("PAM: setting PAM_TTY to \"%s\"", tty);
 884                 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
 885                 if (sshpam_err != PAM_SUCCESS)
 886                         fatal("PAM: failed to set PAM_TTY: %s",
 887                             pam_strerror(sshpam_handle, sshpam_err));
 888         }
 889 }
 890
 891 void
 892 do_pam_setcred(int init)
 893 {
 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         if (init) {
 900                 debug("PAM: establishing credentials");
 901                 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
 902         } else {
 903                 debug("PAM: reinitializing credentials");
 904                 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
 905         }
 906         if (sshpam_err == PAM_SUCCESS) {
 907                 sshpam_cred_established = 1;
 908                 return;
 909         }
 910         if (sshpam_authenticated)
 911                 fatal("PAM: pam_setcred(): %s",
 912                     pam_strerror(sshpam_handle, sshpam_err));
 913         else
 914                 debug("PAM: pam_setcred(): %s",
 915                     pam_strerror(sshpam_handle, sshpam_err));
 916 }
 917
 918 static int
 919 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
 920     struct pam_response **resp, void *data)
 921 {
 922         char input[PAM_MAX_MSG_SIZE];
 923         struct pam_response *reply;
 924         int i;
 925
 926         debug3("PAM: %s called with %d messages", __func__, n);
 927
 928         *resp = NULL;
 929
 930         if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
 931                 return (PAM_CONV_ERR);
 932
 933         if ((reply = malloc(n * sizeof(*reply))) == NULL)
 934                 return (PAM_CONV_ERR);
 935         memset(reply, 0, n * sizeof(*reply));
 936
 937         for (i = 0; i < n; ++i) {
 938                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 939                 case PAM_PROMPT_ECHO_OFF:
 940                         reply[i].resp =
 941                             read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
 942                             RP_ALLOW_STDIN);
 943                         reply[i].resp_retcode = PAM_SUCCESS;
 944                         break;
 945                 case PAM_PROMPT_ECHO_ON:
 946                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 947                         fgets(input, sizeof input, stdin);
 948                         if ((reply[i].resp = strdup(input)) == NULL)
 949                                 goto fail;
 950                         reply[i].resp_retcode = PAM_SUCCESS;
 951                         break;
 952                 case PAM_ERROR_MSG:
 953                 case PAM_TEXT_INFO:
 954                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 955                         reply[i].resp_retcode = PAM_SUCCESS;
 956                         break;
 957                 default:
 958                         goto fail;
 959                 }
 960         }
 961         *resp = reply;
 962         return (PAM_SUCCESS);
 963
 964  fail:
 965         for(i = 0; i < n; i++) {
 966                 if (reply[i].resp != NULL)
 967                         xfree(reply[i].resp);
 968         }
 969         xfree(reply);
 970         return (PAM_CONV_ERR);
 971 }
 972
 973 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
 974
 975 /*
 976  * XXX this should be done in the authentication phase, but ssh1 doesn't
 977  * support that
 978  */
 979 void
 980 do_pam_chauthtok(void)
 981 {
 982         if (use_privsep)
 983                 fatal("Password expired (unable to change with privsep)");
 984         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 985             (const void *)&tty_conv);
 986         if (sshpam_err != PAM_SUCCESS)
 987                 fatal("PAM: failed to set PAM_CONV: %s",
 988                     pam_strerror(sshpam_handle, sshpam_err));
 989         debug("PAM: changing password");
 990         sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
 991         if (sshpam_err != PAM_SUCCESS)
 992                 fatal("PAM: pam_chauthtok(): %s",
 993                     pam_strerror(sshpam_handle, sshpam_err));
 994 }
 995
 996 void
 997 do_pam_session(void)
 998 {
 999         debug3("PAM: opening session");
1000         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1001             (const void *)&store_conv);
1002         if (sshpam_err != PAM_SUCCESS)
1003                 fatal("PAM: failed to set PAM_CONV: %s",
1004                     pam_strerror(sshpam_handle, sshpam_err));
1005         sshpam_err = pam_open_session(sshpam_handle, 0);
1006         if (sshpam_err == PAM_SUCCESS)
1007                 sshpam_session_open = 1;
1008         else {
1009                 sshpam_session_open = 0;
1010                 disable_forwarding();
1011                 error("PAM: pam_open_session(): %s",
1012                     pam_strerror(sshpam_handle, sshpam_err));
1013         }
1014
1015 }
1016
1017 int
1018 is_pam_session_open(void)
1019 {
1020         return sshpam_session_open;
1021 }
1022
1023 /*
1024  * Set a PAM environment string. We need to do this so that the session
1025  * modules can handle things like Kerberos/GSI credentials that appear
1026  * during the ssh authentication process.
1027  */
1028 int
1029 do_pam_putenv(char *name, char *value)
1030 {
1031         int ret = 1;
1032 #ifdef HAVE_PAM_PUTENV
1033         char *compound;
1034         size_t len;
1035
1036         len = strlen(name) + strlen(value) + 2;
1037         compound = xmalloc(len);
1038
1039         snprintf(compound, len, "%s=%s", name, value);
1040         ret = pam_putenv(sshpam_handle, compound);
1041         xfree(compound);
1042 #endif
1043
1044         return (ret);
1045 }
1046
1047 char **
1048 fetch_pam_child_environment(void)
1049 {
1050         return sshpam_env;
1051 }
1052
1053 char **
1054 fetch_pam_environment(void)
1055 {
1056         return (pam_getenvlist(sshpam_handle));
1057 }
1058
1059 void
1060 free_pam_environment(char **env)
1061 {
1062         char **envp;
1063
1064         if (env == NULL)
1065                 return;
1066
1067         for (envp = env; *envp; envp++)
1068                 xfree(*envp);
1069         xfree(env);
1070 }
1071
1072 /*
1073  * "Blind" conversation function for password authentication.  Assumes that
1074  * echo-off prompts are for the password and stores messages for later
1075  * display.
1076  */
1077 static int
1078 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1079     struct pam_response **resp, void *data)
1080 {
1081         struct pam_response *reply;
1082         int i;
1083         size_t len;
1084
1085         debug3("PAM: %s called with %d messages", __func__, n);
1086
1087         *resp = NULL;
1088
1089         if (n <= 0 || n > PAM_MAX_NUM_MSG)
1090                 return (PAM_CONV_ERR);
1091
1092         if ((reply = malloc(n * sizeof(*reply))) == NULL)
1093                 return (PAM_CONV_ERR);
1094         memset(reply, 0, n * sizeof(*reply));
1095
1096         for (i = 0; i < n; ++i) {
1097                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1098                 case PAM_PROMPT_ECHO_OFF:
1099                         if (sshpam_password == NULL)
1100                                 goto fail;
1101                         if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1102                                 goto fail;
1103                         reply[i].resp_retcode = PAM_SUCCESS;
1104                         break;
1105                 case PAM_ERROR_MSG:
1106                 case PAM_TEXT_INFO:
1107                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1108                         if (len > 0) {
1109                                 buffer_append(&loginmsg,
1110                                     PAM_MSG_MEMBER(msg, i, msg), len);
1111                                 buffer_append(&loginmsg, "\n", 1);
1112                         }
1113                         if ((reply[i].resp = strdup("")) == NULL)
1114                                 goto fail;
1115                         reply[i].resp_retcode = PAM_SUCCESS;
1116                         break;
1117                 default:
1118                         goto fail;
1119                 }
1120         }
1121         *resp = reply;
1122         return (PAM_SUCCESS);
1123
1124  fail:
1125         for(i = 0; i < n; i++) {
1126                 if (reply[i].resp != NULL)
1127                         xfree(reply[i].resp);
1128         }
1129         xfree(reply);
1130         return (PAM_CONV_ERR);
1131 }
1132
1133 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1134
1135 /*
1136  * Attempt password authentication via PAM
1137  */
1138 int
1139 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1140 {
1141         int flags = (options.permit_empty_passwd == 0 ?
1142             PAM_DISALLOW_NULL_AUTHTOK : 0);
1143
1144         if (!options.use_pam || sshpam_handle == NULL)
1145                 fatal("PAM: %s called when PAM disabled or failed to "
1146                     "initialise.", __func__);
1147
1148         sshpam_password = password;
1149         sshpam_authctxt = authctxt;
1150
1151         /*
1152          * If the user logging in is invalid, or is root but is not permitted
1153          * by PermitRootLogin, use an invalid password to prevent leaking
1154          * information via timing (eg if the PAM config has a delay on fail).
1155          */
1156         if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1157             options.permit_root_login != PERMIT_YES))
1158                 sshpam_password = badpw;
1159
1160         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1161             (const void *)&passwd_conv);
1162         if (sshpam_err != PAM_SUCCESS)
1163                 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1164                     pam_strerror(sshpam_handle, sshpam_err));
1165
1166         sshpam_err = pam_authenticate(sshpam_handle, flags);
1167         sshpam_password = NULL;
1168         if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1169                 debug("PAM: password authentication accepted for %.100s",
1170                     authctxt->user);
1171                 return 1;
1172         } else {
1173                 debug("PAM: password authentication failed for %.100s: %s",
1174                     authctxt->valid ? authctxt->user : "an illegal user",
1175                     pam_strerror(sshpam_handle, sshpam_err));
1176                 return 0;
1177         }
1178 }
1179 #endif /* USE_PAM */