crypto/openssh/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 */
  49
  50 #include "includes.h"
  51
  52 #include <sys/types.h>
  53 #include <sys/stat.h>
  54 #include <sys/wait.h>
  55
  56 #include <errno.h>
  57 #include <signal.h>
  58 #include <stdarg.h>
  59 #include <string.h>
  60 #include <unistd.h>
  61
  62 #ifdef USE_PAM
  63 #if defined(HAVE_SECURITY_PAM_APPL_H)
  64 #include <security/pam_appl.h>
  65 #elif defined (HAVE_PAM_PAM_APPL_H)
  66 #include <pam/pam_appl.h>
  67 #endif
  68
  69 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */
  70 #ifdef PAM_SUN_CODEBASE
  71 # define sshpam_const           /* Solaris, HP-UX, AIX */
  72 #else
  73 # define sshpam_const   const   /* LinuxPAM, OpenPAM */
  74 #endif
  75
  76 /* Ambiguity in spec: is it an array of pointers or a pointer to an array? */
  77 #ifdef PAM_SUN_CODEBASE
  78 # define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member)
  79 #else
  80 # define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member)
  81 #endif
  82
  83 #include "xmalloc.h"
  84 #include "buffer.h"
  85 #include "key.h"
  86 #include "hostfile.h"
  87 #include "auth.h"
  88 #include "auth-pam.h"
  89 #include "canohost.h"
  90 #include "log.h"
  91 #include "msg.h"
  92 #include "packet.h"
  93 #include "misc.h"
  94 #include "servconf.h"
  95 #include "ssh2.h"
  96 #include "auth-options.h"
  97 #ifdef GSSAPI
  98 #include "ssh-gss.h"
  99 #endif
 100 #include "monitor_wrap.h"
 101 #include "blacklist_client.h"
 102
 103 extern ServerOptions options;
 104 extern Buffer loginmsg;
 105 extern int compat20;
 106 extern u_int utmp_len;
 107
 108 /* so we don't silently change behaviour */
 109 #ifdef USE_POSIX_THREADS
 110 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
 111 #endif
 112
 113 /*
 114  * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
 115  * and generally a bad idea.  Use at own risk and do not expect support if
 116  * this breaks.
 117  */
 118 #ifdef UNSUPPORTED_POSIX_THREADS_HACK
 119 #include <pthread.h>
 120 /*
 121  * Avoid namespace clash when *not* using pthreads for systems *with*
 122  * pthreads, which unconditionally define pthread_t via sys/types.h
 123  * (e.g. Linux)
 124  */
 125 typedef pthread_t sp_pthread_t;
 126 #else
 127 typedef pid_t sp_pthread_t;
 128 #endif
 129
 130 struct pam_ctxt {
 131         sp_pthread_t     pam_thread;
 132         int              pam_psock;
 133         int              pam_csock;
 134         int              pam_done;
 135 };
 136
 137 static void sshpam_free_ctx(void *);
 138 static struct pam_ctxt *cleanup_ctxt;
 139
 140 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 141 /*
 142  * Simulate threads with processes.
 143  */
 144
 145 static int sshpam_thread_status = -1;
 146 static mysig_t sshpam_oldsig;
 147
 148 static void
 149 sshpam_sigchld_handler(int sig)
 150 {
 151         signal(SIGCHLD, SIG_DFL);
 152         if (cleanup_ctxt == NULL)
 153                 return; /* handler called after PAM cleanup, shouldn't happen */
 154         if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
 155             <= 0) {
 156                 /* PAM thread has not exitted, privsep slave must have */
 157                 kill(cleanup_ctxt->pam_thread, SIGTERM);
 158                 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0)
 159                     <= 0)
 160                         return; /* could not wait */
 161         }
 162         if (WIFSIGNALED(sshpam_thread_status) &&
 163             WTERMSIG(sshpam_thread_status) == SIGTERM)
 164                 return; /* terminated by pthread_cancel */
 165         if (!WIFEXITED(sshpam_thread_status))
 166                 sigdie("PAM: authentication thread exited unexpectedly");
 167         if (WEXITSTATUS(sshpam_thread_status) != 0)
 168                 sigdie("PAM: authentication thread exited uncleanly");
 169 }
 170
 171 /* ARGSUSED */
 172 static void
 173 pthread_exit(void *value)
 174 {
 175         _exit(0);
 176 }
 177
 178 /* ARGSUSED */
 179 static int
 180 pthread_create(sp_pthread_t *thread, const void *attr,
 181     void *(*thread_start)(void *), void *arg)
 182 {
 183         pid_t pid;
 184         struct pam_ctxt *ctx = arg;
 185
 186         sshpam_thread_status = -1;
 187         switch ((pid = fork())) {
 188         case -1:
 189                 error("fork(): %s", strerror(errno));
 190                 return (-1);
 191         case 0:
 192                 close(ctx->pam_psock);
 193                 ctx->pam_psock = -1;
 194                 thread_start(arg);
 195                 _exit(1);
 196         default:
 197                 *thread = pid;
 198                 close(ctx->pam_csock);
 199                 ctx->pam_csock = -1;
 200                 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
 201                 return (0);
 202         }
 203 }
 204
 205 static int
 206 pthread_cancel(sp_pthread_t thread)
 207 {
 208         signal(SIGCHLD, sshpam_oldsig);
 209         return (kill(thread, SIGTERM));
 210 }
 211
 212 /* ARGSUSED */
 213 static int
 214 pthread_join(sp_pthread_t thread, void **value)
 215 {
 216         int status;
 217
 218         if (sshpam_thread_status != -1)
 219                 return (sshpam_thread_status);
 220         signal(SIGCHLD, sshpam_oldsig);
 221         waitpid(thread, &status, 0);
 222         return (status);
 223 }
 224 #endif
 225
 226
 227 static pam_handle_t *sshpam_handle = NULL;
 228 static int sshpam_err = 0;
 229 static int sshpam_authenticated = 0;
 230 static int sshpam_session_open = 0;
 231 static int sshpam_cred_established = 0;
 232 static int sshpam_account_status = -1;
 233 static char **sshpam_env = NULL;
 234 static Authctxt *sshpam_authctxt = NULL;
 235 static const char *sshpam_password = NULL;
 236 static char badpw[] = "\b\n\r\177INCORRECT";
 237
 238 /* Some PAM implementations don't implement this */
 239 #ifndef HAVE_PAM_GETENVLIST
 240 static char **
 241 pam_getenvlist(pam_handle_t *pamh)
 242 {
 243         /*
 244          * XXX - If necessary, we can still support envrionment passing
 245          * for platforms without pam_getenvlist by searching for known
 246          * env vars (e.g. KRB5CCNAME) from the PAM environment.
 247          */
 248          return NULL;
 249 }
 250 #endif
 251
 252 /*
 253  * Some platforms, notably Solaris, do not enforce password complexity
 254  * rules during pam_chauthtok() if the real uid of the calling process
 255  * is 0, on the assumption that it's being called by "passwd" run by root.
 256  * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
 257  * the right thing.
 258  */
 259 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
 260 static int
 261 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
 262 {
 263         int result;
 264
 265         if (sshpam_authctxt == NULL)
 266                 fatal("PAM: sshpam_authctxt not initialized");
 267         if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
 268                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 269         result = pam_chauthtok(pamh, flags);
 270         if (setreuid(0, -1) == -1)
 271                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 272         return result;
 273 }
 274 # define pam_chauthtok(a,b)     (sshpam_chauthtok_ruid((a), (b)))
 275 #endif
 276
 277 void
 278 sshpam_password_change_required(int reqd)
 279 {
 280         debug3("%s %d", __func__, reqd);
 281         if (sshpam_authctxt == NULL)
 282                 fatal("%s: PAM authctxt not initialized", __func__);
 283         sshpam_authctxt->force_pwchange = reqd;
 284         if (reqd) {
 285                 no_port_forwarding_flag |= 2;
 286                 no_agent_forwarding_flag |= 2;
 287                 no_x11_forwarding_flag |= 2;
 288         } else {
 289                 no_port_forwarding_flag &= ~2;
 290                 no_agent_forwarding_flag &= ~2;
 291                 no_x11_forwarding_flag &= ~2;
 292         }
 293 }
 294
 295 /* Import regular and PAM environment from subprocess */
 296 static void
 297 import_environments(Buffer *b)
 298 {
 299         char *env;
 300         u_int i, num_env;
 301         int err;
 302
 303         debug3("PAM: %s entering", __func__);
 304
 305 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 306         /* Import variables set by do_pam_account */
 307         sshpam_account_status = buffer_get_int(b);
 308         sshpam_password_change_required(buffer_get_int(b));
 309
 310         /* Import environment from subprocess */
 311         num_env = buffer_get_int(b);
 312         if (num_env > 1024)
 313                 fatal("%s: received %u environment variables, expected <= 1024",
 314                     __func__, num_env);
 315         sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env));
 316         debug3("PAM: num env strings %d", num_env);
 317         for(i = 0; i < num_env; i++)
 318                 sshpam_env[i] = buffer_get_string(b, NULL);
 319
 320         sshpam_env[num_env] = NULL;
 321
 322         /* Import PAM environment from subprocess */
 323         num_env = buffer_get_int(b);
 324         debug("PAM: num PAM env strings %d", num_env);
 325         for(i = 0; i < num_env; i++) {
 326                 env = buffer_get_string(b, NULL);
 327
 328 #ifdef HAVE_PAM_PUTENV
 329                 /* Errors are not fatal here */
 330                 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
 331                         error("PAM: pam_putenv: %s",
 332                             pam_strerror(sshpam_handle, sshpam_err));
 333                 }
 334 #endif
 335         }
 336 #endif
 337 }
 338
 339 /*
 340  * Conversation function for authentication thread.
 341  */
 342 static int
 343 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
 344     struct pam_response **resp, void *data)
 345 {
 346         Buffer buffer;
 347         struct pam_ctxt *ctxt;
 348         struct pam_response *reply;
 349         int i;
 350
 351         debug3("PAM: %s entering, %d messages", __func__, n);
 352         *resp = NULL;
 353
 354         if (data == NULL) {
 355                 error("PAM: conversation function passed a null context");
 356                 return (PAM_CONV_ERR);
 357         }
 358         ctxt = data;
 359         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 360                 return (PAM_CONV_ERR);
 361
 362         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 363                 return (PAM_CONV_ERR);
 364
 365         buffer_init(&buffer);
 366         for (i = 0; i < n; ++i) {
 367                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 368                 case PAM_PROMPT_ECHO_OFF:
 369                         buffer_put_cstring(&buffer,
 370                             PAM_MSG_MEMBER(msg, i, msg));
 371                         if (ssh_msg_send(ctxt->pam_csock,
 372                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 373                                 goto fail;
 374                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 375                                 goto fail;
 376                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 377                                 goto fail;
 378                         reply[i].resp = buffer_get_string(&buffer, NULL);
 379                         break;
 380                 case PAM_PROMPT_ECHO_ON:
 381                         buffer_put_cstring(&buffer,
 382                             PAM_MSG_MEMBER(msg, i, msg));
 383                         if (ssh_msg_send(ctxt->pam_csock,
 384                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 385                                 goto fail;
 386                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 387                                 goto fail;
 388                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 389                                 goto fail;
 390                         reply[i].resp = buffer_get_string(&buffer, NULL);
 391                         break;
 392                 case PAM_ERROR_MSG:
 393                         buffer_put_cstring(&buffer,
 394                             PAM_MSG_MEMBER(msg, i, msg));
 395                         if (ssh_msg_send(ctxt->pam_csock,
 396                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 397                                 goto fail;
 398                         break;
 399                 case PAM_TEXT_INFO:
 400                         buffer_put_cstring(&buffer,
 401                             PAM_MSG_MEMBER(msg, i, msg));
 402                         if (ssh_msg_send(ctxt->pam_csock,
 403                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 404                                 goto fail;
 405                         break;
 406                 default:
 407                         goto fail;
 408                 }
 409                 buffer_clear(&buffer);
 410         }
 411         buffer_free(&buffer);
 412         *resp = reply;
 413         return (PAM_SUCCESS);
 414
 415  fail:
 416         for(i = 0; i < n; i++) {
 417                 free(reply[i].resp);
 418         }
 419         free(reply);
 420         buffer_free(&buffer);
 421         return (PAM_CONV_ERR);
 422 }
 423
 424 /*
 425  * Authentication thread.
 426  */
 427 static void *
 428 sshpam_thread(void *ctxtp)
 429 {
 430         struct pam_ctxt *ctxt = ctxtp;
 431         Buffer buffer;
 432         struct pam_conv sshpam_conv;
 433         int flags = (options.permit_empty_passwd == 0 ?
 434             PAM_DISALLOW_NULL_AUTHTOK : 0);
 435 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 436         extern char **environ;
 437         char **env_from_pam;
 438         u_int i;
 439         const char *pam_user;
 440         const char **ptr_pam_user = &pam_user;
 441         char *tz = getenv("TZ");
 442
 443         sshpam_err = pam_get_item(sshpam_handle, PAM_USER,
 444             (sshpam_const void **)ptr_pam_user);
 445         if (sshpam_err != PAM_SUCCESS)
 446                 goto auth_fail;
 447
 448         environ[0] = NULL;
 449         if (tz != NULL)
 450                 if (setenv("TZ", tz, 1) == -1)
 451                         error("PAM: could not set TZ environment: %s",
 452                             strerror(errno));
 453
 454         if (sshpam_authctxt != NULL) {
 455                 setproctitle("%s [pam]",
 456                     sshpam_authctxt->valid ? pam_user : "unknown");
 457         }
 458 #endif
 459
 460         sshpam_conv.conv = sshpam_thread_conv;
 461         sshpam_conv.appdata_ptr = ctxt;
 462
 463         if (sshpam_authctxt == NULL)
 464                 fatal("%s: PAM authctxt not initialized", __func__);
 465
 466         buffer_init(&buffer);
 467         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 468             (const void *)&sshpam_conv);
 469         if (sshpam_err != PAM_SUCCESS)
 470                 goto auth_fail;
 471         sshpam_err = pam_authenticate(sshpam_handle, flags);
 472         if (sshpam_err != PAM_SUCCESS)
 473                 goto auth_fail;
 474
 475         if (compat20) {
 476                 if (!do_pam_account()) {
 477                         sshpam_err = PAM_ACCT_EXPIRED;
 478                         goto auth_fail;
 479                 }
 480                 if (sshpam_authctxt->force_pwchange) {
 481                         sshpam_err = pam_chauthtok(sshpam_handle,
 482                             PAM_CHANGE_EXPIRED_AUTHTOK);
 483                         if (sshpam_err != PAM_SUCCESS)
 484                                 goto auth_fail;
 485                         sshpam_password_change_required(0);
 486                 }
 487         }
 488
 489         buffer_put_cstring(&buffer, "OK");
 490
 491 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 492         /* Export variables set by do_pam_account */
 493         buffer_put_int(&buffer, sshpam_account_status);
 494         buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);
 495
 496         /* Export any environment strings set in child */
 497         for(i = 0; environ[i] != NULL; i++)
 498                 ; /* Count */
 499         buffer_put_int(&buffer, i);
 500         for(i = 0; environ[i] != NULL; i++)
 501                 buffer_put_cstring(&buffer, environ[i]);
 502
 503         /* Export any environment strings set by PAM in child */
 504         env_from_pam = pam_getenvlist(sshpam_handle);
 505         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 506                 ; /* Count */
 507         buffer_put_int(&buffer, i);
 508         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 509                 buffer_put_cstring(&buffer, env_from_pam[i]);
 510 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */
 511
 512         /* XXX - can't do much about an error here */
 513         ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
 514         buffer_free(&buffer);
 515         pthread_exit(NULL);
 516
 517  auth_fail:
 518         buffer_put_cstring(&buffer,
 519             pam_strerror(sshpam_handle, sshpam_err));
 520         /* XXX - can't do much about an error here */
 521         if (sshpam_err == PAM_ACCT_EXPIRED)
 522                 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, &buffer);
 523         else
 524                 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
 525         buffer_free(&buffer);
 526         pthread_exit(NULL);
 527
 528         return (NULL); /* Avoid warning for non-pthread case */
 529 }
 530
 531 void
 532 sshpam_thread_cleanup(void)
 533 {
 534         struct pam_ctxt *ctxt = cleanup_ctxt;
 535
 536         debug3("PAM: %s entering", __func__);
 537         if (ctxt != NULL && ctxt->pam_thread != 0) {
 538                 pthread_cancel(ctxt->pam_thread);
 539                 pthread_join(ctxt->pam_thread, NULL);
 540                 close(ctxt->pam_psock);
 541                 close(ctxt->pam_csock);
 542                 memset(ctxt, 0, sizeof(*ctxt));
 543                 cleanup_ctxt = NULL;
 544         }
 545 }
 546
 547 static int
 548 sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
 549     struct pam_response **resp, void *data)
 550 {
 551         debug3("PAM: %s entering, %d messages", __func__, n);
 552         return (PAM_CONV_ERR);
 553 }
 554
 555 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
 556
 557 static int
 558 sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
 559     struct pam_response **resp, void *data)
 560 {
 561         struct pam_response *reply;
 562         int i;
 563         size_t len;
 564
 565         debug3("PAM: %s called with %d messages", __func__, n);
 566         *resp = NULL;
 567
 568         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 569                 return (PAM_CONV_ERR);
 570
 571         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 572                 return (PAM_CONV_ERR);
 573
 574         for (i = 0; i < n; ++i) {
 575                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 576                 case PAM_ERROR_MSG:
 577                 case PAM_TEXT_INFO:
 578                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
 579                         buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
 580                         buffer_append(&loginmsg, "\n", 1 );
 581                         reply[i].resp_retcode = PAM_SUCCESS;
 582                         break;
 583                 default:
 584                         goto fail;
 585                 }
 586         }
 587         *resp = reply;
 588         return (PAM_SUCCESS);
 589
 590  fail:
 591         for(i = 0; i < n; i++) {
 592                 free(reply[i].resp);
 593         }
 594         free(reply);
 595         return (PAM_CONV_ERR);
 596 }
 597
 598 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
 599
 600 void
 601 sshpam_cleanup(void)
 602 {
 603         if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor()))
 604                 return;
 605         debug("PAM: cleanup");
 606         pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 607         if (sshpam_session_open) {
 608                 debug("PAM: closing session");
 609                 pam_close_session(sshpam_handle, PAM_SILENT);
 610                 sshpam_session_open = 0;
 611         }
 612         if (sshpam_cred_established) {
 613                 debug("PAM: deleting credentials");
 614                 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
 615                 sshpam_cred_established = 0;
 616         }
 617         sshpam_authenticated = 0;
 618         pam_end(sshpam_handle, sshpam_err);
 619         sshpam_handle = NULL;
 620 }
 621
 622 static int
 623 sshpam_init(Authctxt *authctxt)
 624 {
 625         extern char *__progname;
 626         const char *pam_rhost, *pam_user, *user = authctxt->user;
 627         const char **ptr_pam_user = &pam_user;
 628
 629         if (sshpam_handle != NULL) {
 630                 /* We already have a PAM context; check if the user matches */
 631                 sshpam_err = pam_get_item(sshpam_handle,
 632                     PAM_USER, (sshpam_const void **)ptr_pam_user);
 633                 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
 634                         return (0);
 635                 pam_end(sshpam_handle, sshpam_err);
 636                 sshpam_handle = NULL;
 637         }
 638         debug("PAM: initializing for \"%s\"", user);
 639         sshpam_err =
 640             pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
 641         sshpam_authctxt = authctxt;
 642
 643         if (sshpam_err != PAM_SUCCESS) {
 644                 pam_end(sshpam_handle, sshpam_err);
 645                 sshpam_handle = NULL;
 646                 return (-1);
 647         }
 648         pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
 649         debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
 650         sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
 651         if (sshpam_err != PAM_SUCCESS) {
 652                 pam_end(sshpam_handle, sshpam_err);
 653                 sshpam_handle = NULL;
 654                 return (-1);
 655         }
 656 #ifdef PAM_TTY_KLUDGE
 657         /*
 658          * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
 659          * sshd doesn't set the tty until too late in the auth process and
 660          * may not even set one (for tty-less connections)
 661          */
 662         debug("PAM: setting PAM_TTY to \"ssh\"");
 663         sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
 664         if (sshpam_err != PAM_SUCCESS) {
 665                 pam_end(sshpam_handle, sshpam_err);
 666                 sshpam_handle = NULL;
 667                 return (-1);
 668         }
 669 #endif
 670         return (0);
 671 }
 672
 673 static void *
 674 sshpam_init_ctx(Authctxt *authctxt)
 675 {
 676         struct pam_ctxt *ctxt;
 677         int socks[2];
 678
 679         debug3("PAM: %s entering", __func__);
 680         /*
 681          * Refuse to start if we don't have PAM enabled or do_pam_account
 682          * has previously failed.
 683          */
 684         if (!options.use_pam || sshpam_account_status == 0)
 685                 return NULL;
 686
 687         /* Initialize PAM */
 688         if (sshpam_init(authctxt) == -1) {
 689                 error("PAM: initialization failed");
 690                 return (NULL);
 691         }
 692
 693         ctxt = xcalloc(1, sizeof *ctxt);
 694
 695         /* Start the authentication thread */
 696         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
 697                 error("PAM: failed create sockets: %s", strerror(errno));
 698                 free(ctxt);
 699                 return (NULL);
 700         }
 701         ctxt->pam_psock = socks[0];
 702         ctxt->pam_csock = socks[1];
 703         if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
 704                 error("PAM: failed to start authentication thread: %s",
 705                     strerror(errno));
 706                 close(socks[0]);
 707                 close(socks[1]);
 708                 free(ctxt);
 709                 return (NULL);
 710         }
 711         cleanup_ctxt = ctxt;
 712         return (ctxt);
 713 }
 714
 715 static int
 716 sshpam_query(void *ctx, char **name, char **info,
 717     u_int *num, char ***prompts, u_int **echo_on)
 718 {
 719         Buffer buffer;
 720         struct pam_ctxt *ctxt = ctx;
 721         size_t plen;
 722         u_char type;
 723         char *msg;
 724         size_t len, mlen;
 725
 726         debug3("PAM: %s entering", __func__);
 727         buffer_init(&buffer);
 728         *name = xstrdup("");
 729         *info = xstrdup("");
 730         *prompts = xmalloc(sizeof(char *));
 731         **prompts = NULL;
 732         plen = 0;
 733         *echo_on = xmalloc(sizeof(u_int));
 734         while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
 735                 type = buffer_get_char(&buffer);
 736                 msg = buffer_get_string(&buffer, NULL);
 737                 mlen = strlen(msg);
 738                 switch (type) {
 739                 case PAM_PROMPT_ECHO_ON:
 740                 case PAM_PROMPT_ECHO_OFF:
 741                         *num = 1;
 742                         len = plen + mlen + 1;
 743                         **prompts = xreallocarray(**prompts, 1, len);
 744                         strlcpy(**prompts + plen, msg, len - plen);
 745                         plen += mlen;
 746                         **echo_on = (type == PAM_PROMPT_ECHO_ON);
 747                         free(msg);
 748                         return (0);
 749                 case PAM_ERROR_MSG:
 750                 case PAM_TEXT_INFO:
 751                         /* accumulate messages */
 752                         len = plen + mlen + 2;
 753                         **prompts = xreallocarray(**prompts, 1, len);
 754                         strlcpy(**prompts + plen, msg, len - plen);
 755                         plen += mlen;
 756                         strlcat(**prompts + plen, "\n", len - plen);
 757                         plen++;
 758                         free(msg);
 759                         break;
 760                 case PAM_ACCT_EXPIRED:
 761                         sshpam_account_status = 0;
 762                         /* FALLTHROUGH */
 763                 case PAM_AUTH_ERR:
 764                         debug3("PAM: %s", pam_strerror(sshpam_handle, type));
 765                         if (**prompts != NULL && strlen(**prompts) != 0) {
 766                                 *info = **prompts;
 767                                 **prompts = NULL;
 768                                 *num = 0;
 769                                 **echo_on = 0;
 770                                 ctxt->pam_done = -1;
 771                                 free(msg);
 772                                 return 0;
 773                         }
 774                         /* FALLTHROUGH */
 775                 case PAM_SUCCESS:
 776                         if (**prompts != NULL) {
 777                                 /* drain any accumulated messages */
 778                                 debug("PAM: %s", **prompts);
 779                                 buffer_append(&loginmsg, **prompts,
 780                                     strlen(**prompts));
 781                                 free(**prompts);
 782                                 **prompts = NULL;
 783                         }
 784                         if (type == PAM_SUCCESS) {
 785                                 if (!sshpam_authctxt->valid ||
 786                                     (sshpam_authctxt->pw->pw_uid == 0 &&
 787                                     options.permit_root_login != PERMIT_YES))
 788                                         fatal("Internal error: PAM auth "
 789                                             "succeeded when it should have "
 790                                             "failed");
 791                                 import_environments(&buffer);
 792                                 *num = 0;
 793                                 **echo_on = 0;
 794                                 ctxt->pam_done = 1;
 795                                 free(msg);
 796                                 return (0);
 797                         }
 798                         BLACKLIST_NOTIFY(BLACKLIST_AUTH_FAIL);
 799                         error("PAM: %s for %s%.100s from %.100s", msg,
 800                             sshpam_authctxt->valid ? "" : "illegal user ",
 801                             sshpam_authctxt->user,
 802                             get_remote_name_or_ip(utmp_len, options.use_dns));
 803                         /* FALLTHROUGH */
 804                 default:
 805                         *num = 0;
 806                         **echo_on = 0;
 807                         free(msg);
 808                         ctxt->pam_done = -1;
 809                         return (-1);
 810                 }
 811         }
 812         return (-1);
 813 }
 814
 815 /* XXX - see also comment in auth-chall.c:verify_response */
 816 static int
 817 sshpam_respond(void *ctx, u_int num, char **resp)
 818 {
 819         Buffer buffer;
 820         struct pam_ctxt *ctxt = ctx;
 821
 822         debug2("PAM: %s entering, %u responses", __func__, num);
 823         switch (ctxt->pam_done) {
 824         case 1:
 825                 sshpam_authenticated = 1;
 826                 return (0);
 827         case 0:
 828                 break;
 829         default:
 830                 return (-1);
 831         }
 832         if (num != 1) {
 833                 error("PAM: expected one response, got %u", num);
 834                 return (-1);
 835         }
 836         buffer_init(&buffer);
 837         if (sshpam_authctxt->valid &&
 838             (sshpam_authctxt->pw->pw_uid != 0 ||
 839             options.permit_root_login == PERMIT_YES))
 840                 buffer_put_cstring(&buffer, *resp);
 841         else
 842                 buffer_put_cstring(&buffer, badpw);
 843         if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
 844                 buffer_free(&buffer);
 845                 return (-1);
 846         }
 847         buffer_free(&buffer);
 848         return (1);
 849 }
 850
 851 static void
 852 sshpam_free_ctx(void *ctxtp)
 853 {
 854         struct pam_ctxt *ctxt = ctxtp;
 855
 856         debug3("PAM: %s entering", __func__);
 857         sshpam_thread_cleanup();
 858         free(ctxt);
 859         /*
 860          * We don't call sshpam_cleanup() here because we may need the PAM
 861          * handle at a later stage, e.g. when setting up a session.  It's
 862          * still on the cleanup list, so pam_end() *will* be called before
 863          * the server process terminates.
 864          */
 865 }
 866
 867 KbdintDevice sshpam_device = {
 868         "pam",
 869         sshpam_init_ctx,
 870         sshpam_query,
 871         sshpam_respond,
 872         sshpam_free_ctx
 873 };
 874
 875 KbdintDevice mm_sshpam_device = {
 876         "pam",
 877         mm_sshpam_init_ctx,
 878         mm_sshpam_query,
 879         mm_sshpam_respond,
 880         mm_sshpam_free_ctx
 881 };
 882
 883 /*
 884  * This replaces auth-pam.c
 885  */
 886 void
 887 start_pam(Authctxt *authctxt)
 888 {
 889         if (!options.use_pam)
 890                 fatal("PAM: initialisation requested when UsePAM=no");
 891
 892         if (sshpam_init(authctxt) == -1)
 893                 fatal("PAM: initialisation failed");
 894 }
 895
 896 void
 897 finish_pam(void)
 898 {
 899         sshpam_cleanup();
 900 }
 901
 902 u_int
 903 do_pam_account(void)
 904 {
 905         debug("%s: called", __func__);
 906         if (sshpam_account_status != -1)
 907                 return (sshpam_account_status);
 908
 909         sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
 910         debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
 911             pam_strerror(sshpam_handle, sshpam_err));
 912
 913         if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
 914                 sshpam_account_status = 0;
 915                 return (sshpam_account_status);
 916         }
 917
 918         if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
 919                 sshpam_password_change_required(1);
 920
 921         sshpam_account_status = 1;
 922         return (sshpam_account_status);
 923 }
 924
 925 void
 926 do_pam_set_tty(const char *tty)
 927 {
 928         if (tty != NULL) {
 929                 debug("PAM: setting PAM_TTY to \"%s\"", tty);
 930                 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
 931                 if (sshpam_err != PAM_SUCCESS)
 932                         fatal("PAM: failed to set PAM_TTY: %s",
 933                             pam_strerror(sshpam_handle, sshpam_err));
 934         }
 935 }
 936
 937 void
 938 do_pam_setcred(int init)
 939 {
 940         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 941             (const void *)&store_conv);
 942         if (sshpam_err != PAM_SUCCESS)
 943                 fatal("PAM: failed to set PAM_CONV: %s",
 944                     pam_strerror(sshpam_handle, sshpam_err));
 945         if (init) {
 946                 debug("PAM: establishing credentials");
 947                 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
 948         } else {
 949                 debug("PAM: reinitializing credentials");
 950                 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
 951         }
 952         if (sshpam_err == PAM_SUCCESS) {
 953                 sshpam_cred_established = 1;
 954                 return;
 955         }
 956         if (sshpam_authenticated)
 957                 fatal("PAM: pam_setcred(): %s",
 958                     pam_strerror(sshpam_handle, sshpam_err));
 959         else
 960                 debug("PAM: pam_setcred(): %s",
 961                     pam_strerror(sshpam_handle, sshpam_err));
 962 }
 963
 964 static int
 965 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
 966     struct pam_response **resp, void *data)
 967 {
 968         char input[PAM_MAX_MSG_SIZE];
 969         struct pam_response *reply;
 970         int i;
 971
 972         debug3("PAM: %s called with %d messages", __func__, n);
 973
 974         *resp = NULL;
 975
 976         if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
 977                 return (PAM_CONV_ERR);
 978
 979         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 980                 return (PAM_CONV_ERR);
 981
 982         for (i = 0; i < n; ++i) {
 983                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 984                 case PAM_PROMPT_ECHO_OFF:
 985                         reply[i].resp =
 986                             read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
 987                             RP_ALLOW_STDIN);
 988                         reply[i].resp_retcode = PAM_SUCCESS;
 989                         break;
 990                 case PAM_PROMPT_ECHO_ON:
 991                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 992                         if (fgets(input, sizeof input, stdin) == NULL)
 993                                 input[0] = '\0';
 994                         if ((reply[i].resp = strdup(input)) == NULL)
 995                                 goto fail;
 996                         reply[i].resp_retcode = PAM_SUCCESS;
 997                         break;
 998                 case PAM_ERROR_MSG:
 999                 case PAM_TEXT_INFO:
1000                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1001                         reply[i].resp_retcode = PAM_SUCCESS;
1002                         break;
1003                 default:
1004                         goto fail;
1005                 }
1006         }
1007         *resp = reply;
1008         return (PAM_SUCCESS);
1009
1010  fail:
1011         for(i = 0; i < n; i++) {
1012                 free(reply[i].resp);
1013         }
1014         free(reply);
1015         return (PAM_CONV_ERR);
1016 }
1017
1018 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
1019
1020 /*
1021  * XXX this should be done in the authentication phase, but ssh1 doesn't
1022  * support that
1023  */
1024 void
1025 do_pam_chauthtok(void)
1026 {
1027         if (use_privsep)
1028                 fatal("Password expired (unable to change with privsep)");
1029         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1030             (const void *)&tty_conv);
1031         if (sshpam_err != PAM_SUCCESS)
1032                 fatal("PAM: failed to set PAM_CONV: %s",
1033                     pam_strerror(sshpam_handle, sshpam_err));
1034         debug("PAM: changing password");
1035         sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
1036         if (sshpam_err != PAM_SUCCESS)
1037                 fatal("PAM: pam_chauthtok(): %s",
1038                     pam_strerror(sshpam_handle, sshpam_err));
1039 }
1040
1041 void
1042 do_pam_session(void)
1043 {
1044         debug3("PAM: opening session");
1045         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1046             (const void *)&store_conv);
1047         if (sshpam_err != PAM_SUCCESS)
1048                 fatal("PAM: failed to set PAM_CONV: %s",
1049                     pam_strerror(sshpam_handle, sshpam_err));
1050         sshpam_err = pam_open_session(sshpam_handle, 0);
1051         if (sshpam_err == PAM_SUCCESS)
1052                 sshpam_session_open = 1;
1053         else {
1054                 sshpam_session_open = 0;
1055                 disable_forwarding();
1056                 error("PAM: pam_open_session(): %s",
1057                     pam_strerror(sshpam_handle, sshpam_err));
1058         }
1059
1060 }
1061
1062 int
1063 is_pam_session_open(void)
1064 {
1065         return sshpam_session_open;
1066 }
1067
1068 /*
1069  * Set a PAM environment string. We need to do this so that the session
1070  * modules can handle things like Kerberos/GSI credentials that appear
1071  * during the ssh authentication process.
1072  */
1073 int
1074 do_pam_putenv(char *name, char *value)
1075 {
1076         int ret = 1;
1077 #ifdef HAVE_PAM_PUTENV
1078         char *compound;
1079         size_t len;
1080
1081         len = strlen(name) + strlen(value) + 2;
1082         compound = xmalloc(len);
1083
1084         snprintf(compound, len, "%s=%s", name, value);
1085         ret = pam_putenv(sshpam_handle, compound);
1086         free(compound);
1087 #endif
1088
1089         return (ret);
1090 }
1091
1092 char **
1093 fetch_pam_child_environment(void)
1094 {
1095         return sshpam_env;
1096 }
1097
1098 char **
1099 fetch_pam_environment(void)
1100 {
1101         return (pam_getenvlist(sshpam_handle));
1102 }
1103
1104 void
1105 free_pam_environment(char **env)
1106 {
1107         char **envp;
1108
1109         if (env == NULL)
1110                 return;
1111
1112         for (envp = env; *envp; envp++)
1113                 free(*envp);
1114         free(env);
1115 }
1116
1117 /*
1118  * "Blind" conversation function for password authentication.  Assumes that
1119  * echo-off prompts are for the password and stores messages for later
1120  * display.
1121  */
1122 static int
1123 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1124     struct pam_response **resp, void *data)
1125 {
1126         struct pam_response *reply;
1127         int i;
1128         size_t len;
1129
1130         debug3("PAM: %s called with %d messages", __func__, n);
1131
1132         *resp = NULL;
1133
1134         if (n <= 0 || n > PAM_MAX_NUM_MSG)
1135                 return (PAM_CONV_ERR);
1136
1137         if ((reply = calloc(n, sizeof(*reply))) == NULL)
1138                 return (PAM_CONV_ERR);
1139
1140         for (i = 0; i < n; ++i) {
1141                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1142                 case PAM_PROMPT_ECHO_OFF:
1143                         if (sshpam_password == NULL)
1144                                 goto fail;
1145                         if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1146                                 goto fail;
1147                         reply[i].resp_retcode = PAM_SUCCESS;
1148                         break;
1149                 case PAM_ERROR_MSG:
1150                 case PAM_TEXT_INFO:
1151                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1152                         if (len > 0) {
1153                                 buffer_append(&loginmsg,
1154                                     PAM_MSG_MEMBER(msg, i, msg), len);
1155                                 buffer_append(&loginmsg, "\n", 1);
1156                         }
1157                         if ((reply[i].resp = strdup("")) == NULL)
1158                                 goto fail;
1159                         reply[i].resp_retcode = PAM_SUCCESS;
1160                         break;
1161                 default:
1162                         goto fail;
1163                 }
1164         }
1165         *resp = reply;
1166         return (PAM_SUCCESS);
1167
1168  fail:
1169         for(i = 0; i < n; i++) {
1170                 free(reply[i].resp);
1171         }
1172         free(reply);
1173         return (PAM_CONV_ERR);
1174 }
1175
1176 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1177
1178 /*
1179  * Attempt password authentication via PAM
1180  */
1181 int
1182 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1183 {
1184         int flags = (options.permit_empty_passwd == 0 ?
1185             PAM_DISALLOW_NULL_AUTHTOK : 0);
1186
1187         if (!options.use_pam || sshpam_handle == NULL)
1188                 fatal("PAM: %s called when PAM disabled or failed to "
1189                     "initialise.", __func__);
1190
1191         sshpam_password = password;
1192         sshpam_authctxt = authctxt;
1193
1194         /*
1195          * If the user logging in is invalid, or is root but is not permitted
1196          * by PermitRootLogin, use an invalid password to prevent leaking
1197          * information via timing (eg if the PAM config has a delay on fail).
1198          */
1199         if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1200             options.permit_root_login != PERMIT_YES))
1201                 sshpam_password = badpw;
1202
1203         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1204             (const void *)&passwd_conv);
1205         if (sshpam_err != PAM_SUCCESS)
1206                 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1207                     pam_strerror(sshpam_handle, sshpam_err));
1208
1209         sshpam_err = pam_authenticate(sshpam_handle, flags);
1210         sshpam_password = NULL;
1211         if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1212                 debug("PAM: password authentication accepted for %.100s",
1213                     authctxt->user);
1214                 return 1;
1215         } else {
1216                 debug("PAM: password authentication failed for %.100s: %s",
1217                     authctxt->valid ? authctxt->user : "an illegal user",
1218                     pam_strerror(sshpam_handle, sshpam_err));
1219                 return 0;
1220         }
1221 }
1222 #endif /* USE_PAM */