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 $xFreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des Exp $ */
  49 #include "includes.h"
  50 __RCSID("$FreeBSD$");
  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
 102 extern ServerOptions options;
 103 extern Buffer loginmsg;
 104 extern int compat20;
 105 extern u_int utmp_len;
 106
 107 /* so we don't silently change behaviour */
 108 #ifdef USE_POSIX_THREADS
 109 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
 110 #endif
 111
 112 /*
 113  * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
 114  * and generally a bad idea.  Use at own risk and do not expect support if
 115  * this breaks.
 116  */
 117 #ifdef UNSUPPORTED_POSIX_THREADS_HACK
 118 #include <pthread.h>
 119 /*
 120  * Avoid namespace clash when *not* using pthreads for systems *with*
 121  * pthreads, which unconditionally define pthread_t via sys/types.h
 122  * (e.g. Linux)
 123  */
 124 typedef pthread_t sp_pthread_t;
 125 #else
 126 typedef pid_t sp_pthread_t;
 127 #endif
 128
 129 struct pam_ctxt {
 130         sp_pthread_t     pam_thread;
 131         int              pam_psock;
 132         int              pam_csock;
 133         int              pam_done;
 134 };
 135
 136 static void sshpam_free_ctx(void *);
 137 static struct pam_ctxt *cleanup_ctxt;
 138
 139 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 140 /*
 141  * Simulate threads with processes.
 142  */
 143
 144 static int sshpam_thread_status = -1;
 145 static mysig_t sshpam_oldsig;
 146
 147 static void
 148 sshpam_sigchld_handler(int sig)
 149 {
 150         signal(SIGCHLD, SIG_DFL);
 151         if (cleanup_ctxt == NULL)
 152                 return; /* handler called after PAM cleanup, shouldn't happen */
 153         if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
 154             <= 0) {
 155                 /* PAM thread has not exitted, privsep slave must have */
 156                 kill(cleanup_ctxt->pam_thread, SIGTERM);
 157                 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0)
 158                     <= 0)
 159                         return; /* could not wait */
 160         }
 161         if (WIFSIGNALED(sshpam_thread_status) &&
 162             WTERMSIG(sshpam_thread_status) == SIGTERM)
 163                 return; /* terminated by pthread_cancel */
 164         if (!WIFEXITED(sshpam_thread_status))
 165                 fatal("PAM: authentication thread exited unexpectedly");
 166         if (WEXITSTATUS(sshpam_thread_status) != 0)
 167                 fatal("PAM: authentication thread exited uncleanly");
 168 }
 169
 170 /* ARGSUSED */
 171 static void
 172 pthread_exit(void *value)
 173 {
 174         _exit(0);
 175 }
 176
 177 /* ARGSUSED */
 178 static int
 179 pthread_create(sp_pthread_t *thread, const void *attr,
 180     void *(*thread_start)(void *), void *arg)
 181 {
 182         pid_t pid;
 183         struct pam_ctxt *ctx = arg;
 184
 185         sshpam_thread_status = -1;
 186         switch ((pid = fork())) {
 187         case -1:
 188                 error("fork(): %s", strerror(errno));
 189                 return (-1);
 190         case 0:
 191                 close(ctx->pam_psock);
 192                 ctx->pam_psock = -1;
 193                 thread_start(arg);
 194                 _exit(1);
 195         default:
 196                 *thread = pid;
 197                 close(ctx->pam_csock);
 198                 ctx->pam_csock = -1;
 199                 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
 200                 return (0);
 201         }
 202 }
 203
 204 static int
 205 pthread_cancel(sp_pthread_t thread)
 206 {
 207         signal(SIGCHLD, sshpam_oldsig);
 208         return (kill(thread, SIGTERM));
 209 }
 210
 211 /* ARGSUSED */
 212 static int
 213 pthread_join(sp_pthread_t thread, void **value)
 214 {
 215         int status;
 216
 217         if (sshpam_thread_status != -1)
 218                 return (sshpam_thread_status);
 219         signal(SIGCHLD, sshpam_oldsig);
 220         waitpid(thread, &status, 0);
 221         return (status);
 222 }
 223 #endif
 224
 225
 226 static pam_handle_t *sshpam_handle = NULL;
 227 static int sshpam_err = 0;
 228 static int sshpam_authenticated = 0;
 229 static int sshpam_session_open = 0;
 230 static int sshpam_cred_established = 0;
 231 static int sshpam_account_status = -1;
 232 static char **sshpam_env = NULL;
 233 static Authctxt *sshpam_authctxt = NULL;
 234 static const char *sshpam_password = NULL;
 235 static char badpw[] = "\b\n\r\177INCORRECT";
 236
 237 /* Some PAM implementations don't implement this */
 238 #ifndef HAVE_PAM_GETENVLIST
 239 static char **
 240 pam_getenvlist(pam_handle_t *pamh)
 241 {
 242         /*
 243          * XXX - If necessary, we can still support envrionment passing
 244          * for platforms without pam_getenvlist by searching for known
 245          * env vars (e.g. KRB5CCNAME) from the PAM environment.
 246          */
 247          return NULL;
 248 }
 249 #endif
 250
 251 /*
 252  * Some platforms, notably Solaris, do not enforce password complexity
 253  * rules during pam_chauthtok() if the real uid of the calling process
 254  * is 0, on the assumption that it's being called by "passwd" run by root.
 255  * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
 256  * the right thing.
 257  */
 258 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
 259 static int
 260 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
 261 {
 262         int result;
 263
 264         if (sshpam_authctxt == NULL)
 265                 fatal("PAM: sshpam_authctxt not initialized");
 266         if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
 267                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 268         result = pam_chauthtok(pamh, flags);
 269         if (setreuid(0, -1) == -1)
 270                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 271         return result;
 272 }
 273 # define pam_chauthtok(a,b)     (sshpam_chauthtok_ruid((a), (b)))
 274 #endif
 275
 276 void
 277 sshpam_password_change_required(int reqd)
 278 {
 279         debug3("%s %d", __func__, reqd);
 280         if (sshpam_authctxt == NULL)
 281                 fatal("%s: PAM authctxt not initialized", __func__);
 282         sshpam_authctxt->force_pwchange = reqd;
 283         if (reqd) {
 284                 no_port_forwarding_flag |= 2;
 285                 no_agent_forwarding_flag |= 2;
 286                 no_x11_forwarding_flag |= 2;
 287         } else {
 288                 no_port_forwarding_flag &= ~2;
 289                 no_agent_forwarding_flag &= ~2;
 290                 no_x11_forwarding_flag &= ~2;
 291         }
 292 }
 293
 294 /* Import regular and PAM environment from subprocess */
 295 static void
 296 import_environments(Buffer *b)
 297 {
 298         char *env;
 299         u_int i, num_env;
 300         int err;
 301
 302         debug3("PAM: %s entering", __func__);
 303
 304 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 305         /* Import variables set by do_pam_account */
 306         sshpam_account_status = buffer_get_int(b);
 307         sshpam_password_change_required(buffer_get_int(b));
 308
 309         /* Import environment from subprocess */
 310         num_env = buffer_get_int(b);
 311         if (num_env > 1024)
 312                 fatal("%s: received %u environment variables, expected <= 1024",
 313                     __func__, num_env);
 314         sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env));
 315         debug3("PAM: num env strings %d", num_env);
 316         for(i = 0; i < num_env; i++)
 317                 sshpam_env[i] = buffer_get_string(b, NULL);
 318
 319         sshpam_env[num_env] = NULL;
 320
 321         /* Import PAM environment from subprocess */
 322         num_env = buffer_get_int(b);
 323         debug("PAM: num PAM env strings %d", num_env);
 324         for(i = 0; i < num_env; i++) {
 325                 env = buffer_get_string(b, NULL);
 326
 327 #ifdef HAVE_PAM_PUTENV
 328                 /* Errors are not fatal here */
 329                 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
 330                         error("PAM: pam_putenv: %s",
 331                             pam_strerror(sshpam_handle, sshpam_err));
 332                 }
 333 #endif
 334         }
 335 #endif
 336 }
 337
 338 /*
 339  * Conversation function for authentication thread.
 340  */
 341 static int
 342 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
 343     struct pam_response **resp, void *data)
 344 {
 345         Buffer buffer;
 346         struct pam_ctxt *ctxt;
 347         struct pam_response *reply;
 348         int i;
 349
 350         debug3("PAM: %s entering, %d messages", __func__, n);
 351         *resp = NULL;
 352
 353         if (data == NULL) {
 354                 error("PAM: conversation function passed a null context");
 355                 return (PAM_CONV_ERR);
 356         }
 357         ctxt = data;
 358         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 359                 return (PAM_CONV_ERR);
 360
 361         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 362                 return (PAM_CONV_ERR);
 363
 364         buffer_init(&buffer);
 365         for (i = 0; i < n; ++i) {
 366                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 367                 case PAM_PROMPT_ECHO_OFF:
 368                         buffer_put_cstring(&buffer,
 369                             PAM_MSG_MEMBER(msg, i, msg));
 370                         if (ssh_msg_send(ctxt->pam_csock,
 371                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 372                                 goto fail;
 373                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 374                                 goto fail;
 375                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 376                                 goto fail;
 377                         reply[i].resp = buffer_get_string(&buffer, NULL);
 378                         break;
 379                 case PAM_PROMPT_ECHO_ON:
 380                         buffer_put_cstring(&buffer,
 381                             PAM_MSG_MEMBER(msg, i, msg));
 382                         if (ssh_msg_send(ctxt->pam_csock,
 383                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 384                                 goto fail;
 385                         if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
 386                                 goto fail;
 387                         if (buffer_get_char(&buffer) != PAM_AUTHTOK)
 388                                 goto fail;
 389                         reply[i].resp = buffer_get_string(&buffer, NULL);
 390                         break;
 391                 case PAM_ERROR_MSG:
 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                 case PAM_TEXT_INFO:
 399                         buffer_put_cstring(&buffer,
 400                             PAM_MSG_MEMBER(msg, i, msg));
 401                         if (ssh_msg_send(ctxt->pam_csock,
 402                             PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
 403                                 goto fail;
 404                         break;
 405                 default:
 406                         goto fail;
 407                 }
 408                 buffer_clear(&buffer);
 409         }
 410         buffer_free(&buffer);
 411         *resp = reply;
 412         return (PAM_SUCCESS);
 413
 414  fail:
 415         for(i = 0; i < n; i++) {
 416                 if (reply[i].resp != NULL)
 417                         xfree(reply[i].resp);
 418         }
 419         xfree(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         pam_get_item(sshpam_handle, PAM_USER,
 444             (sshpam_const void **)ptr_pam_user);
 445
 446         environ[0] = NULL;
 447         if (tz != NULL)
 448                 if (setenv("TZ", tz, 1) == -1)
 449                         error("PAM: could not set TZ environment: %s",
 450                             strerror(errno));
 451
 452         if (sshpam_authctxt != NULL) {
 453                 setproctitle("%s [pam]",
 454                     sshpam_authctxt->valid ? pam_user : "unknown");
 455         }
 456 #endif
 457
 458         sshpam_conv.conv = sshpam_thread_conv;
 459         sshpam_conv.appdata_ptr = ctxt;
 460
 461         if (sshpam_authctxt == NULL)
 462                 fatal("%s: PAM authctxt not initialized", __func__);
 463
 464         buffer_init(&buffer);
 465         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 466             (const void *)&sshpam_conv);
 467         if (sshpam_err != PAM_SUCCESS)
 468                 goto auth_fail;
 469         sshpam_err = pam_authenticate(sshpam_handle, flags);
 470         if (sshpam_err != PAM_SUCCESS)
 471                 goto auth_fail;
 472
 473         if (compat20) {
 474                 if (!do_pam_account()) {
 475                         sshpam_err = PAM_ACCT_EXPIRED;
 476                         goto auth_fail;
 477                 }
 478                 if (sshpam_authctxt->force_pwchange) {
 479                         sshpam_err = pam_chauthtok(sshpam_handle,
 480                             PAM_CHANGE_EXPIRED_AUTHTOK);
 481                         if (sshpam_err != PAM_SUCCESS)
 482                                 goto auth_fail;
 483                         sshpam_password_change_required(0);
 484                 }
 485         }
 486
 487         buffer_put_cstring(&buffer, "OK");
 488
 489 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 490         /* Export variables set by do_pam_account */
 491         buffer_put_int(&buffer, sshpam_account_status);
 492         buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);
 493
 494         /* Export any environment strings set in child */
 495         for(i = 0; environ[i] != NULL; i++)
 496                 ; /* Count */
 497         buffer_put_int(&buffer, i);
 498         for(i = 0; environ[i] != NULL; i++)
 499                 buffer_put_cstring(&buffer, environ[i]);
 500
 501         /* Export any environment strings set by PAM in child */
 502         env_from_pam = pam_getenvlist(sshpam_handle);
 503         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 504                 ; /* Count */
 505         buffer_put_int(&buffer, i);
 506         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 507                 buffer_put_cstring(&buffer, env_from_pam[i]);
 508 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */
 509
 510         /* XXX - can't do much about an error here */
 511         ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
 512         buffer_free(&buffer);
 513         pthread_exit(NULL);
 514
 515  auth_fail:
 516         buffer_put_cstring(&buffer,
 517             pam_strerror(sshpam_handle, sshpam_err));
 518         /* XXX - can't do much about an error here */
 519         if (sshpam_err == PAM_ACCT_EXPIRED)
 520                 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, &buffer);
 521         else
 522                 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
 523         buffer_free(&buffer);
 524         pthread_exit(NULL);
 525
 526         return (NULL); /* Avoid warning for non-pthread case */
 527 }
 528
 529 void
 530 sshpam_thread_cleanup(void)
 531 {
 532         struct pam_ctxt *ctxt = cleanup_ctxt;
 533
 534         debug3("PAM: %s entering", __func__);
 535         if (ctxt != NULL && ctxt->pam_thread != 0) {
 536                 pthread_cancel(ctxt->pam_thread);
 537                 pthread_join(ctxt->pam_thread, NULL);
 538                 close(ctxt->pam_psock);
 539                 close(ctxt->pam_csock);
 540                 memset(ctxt, 0, sizeof(*ctxt));
 541                 cleanup_ctxt = NULL;
 542         }
 543 }
 544
 545 static int
 546 sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
 547     struct pam_response **resp, void *data)
 548 {
 549         debug3("PAM: %s entering, %d messages", __func__, n);
 550         return (PAM_CONV_ERR);
 551 }
 552
 553 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
 554
 555 static int
 556 sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
 557     struct pam_response **resp, void *data)
 558 {
 559         struct pam_response *reply;
 560         int i;
 561         size_t len;
 562
 563         debug3("PAM: %s called with %d messages", __func__, n);
 564         *resp = NULL;
 565
 566         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 567                 return (PAM_CONV_ERR);
 568
 569         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 570                 return (PAM_CONV_ERR);
 571
 572         for (i = 0; i < n; ++i) {
 573                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 574                 case PAM_ERROR_MSG:
 575                 case PAM_TEXT_INFO:
 576                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
 577                         buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
 578                         buffer_append(&loginmsg, "\n", 1 );
 579                         reply[i].resp_retcode = PAM_SUCCESS;
 580                         break;
 581                 default:
 582                         goto fail;
 583                 }
 584         }
 585         *resp = reply;
 586         return (PAM_SUCCESS);
 587
 588  fail:
 589         for(i = 0; i < n; i++) {
 590                 if (reply[i].resp != NULL)
 591                         xfree(reply[i].resp);
 592         }
 593         xfree(reply);
 594         return (PAM_CONV_ERR);
 595 }
 596
 597 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
 598
 599 void
 600 sshpam_cleanup(void)
 601 {
 602         debug("PAM: cleanup");
 603         if (sshpam_handle == NULL)
 604                 return;
 605         pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 606         if (sshpam_cred_established) {
 607                 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
 608                 sshpam_cred_established = 0;
 609         }
 610         if (sshpam_session_open) {
 611                 pam_close_session(sshpam_handle, PAM_SILENT);
 612                 sshpam_session_open = 0;
 613         }
 614         sshpam_authenticated = 0;
 615         pam_end(sshpam_handle, sshpam_err);
 616         sshpam_handle = NULL;
 617 }
 618
 619 static int
 620 sshpam_init(Authctxt *authctxt)
 621 {
 622         extern char *__progname;
 623         const char *pam_rhost, *pam_user, *user = authctxt->user;
 624         const char **ptr_pam_user = &pam_user;
 625
 626         if (sshpam_handle != NULL) {
 627                 /* We already have a PAM context; check if the user matches */
 628                 sshpam_err = pam_get_item(sshpam_handle,
 629                     PAM_USER, (sshpam_const void **)ptr_pam_user);
 630                 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
 631                         return (0);
 632                 pam_end(sshpam_handle, sshpam_err);
 633                 sshpam_handle = NULL;
 634         }
 635         debug("PAM: initializing for \"%s\"", user);
 636         sshpam_err =
 637             pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
 638         sshpam_authctxt = authctxt;
 639
 640         if (sshpam_err != PAM_SUCCESS) {
 641                 pam_end(sshpam_handle, sshpam_err);
 642                 sshpam_handle = NULL;
 643                 return (-1);
 644         }
 645         pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
 646         debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
 647         sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
 648         if (sshpam_err != PAM_SUCCESS) {
 649                 pam_end(sshpam_handle, sshpam_err);
 650                 sshpam_handle = NULL;
 651                 return (-1);
 652         }
 653 #ifdef PAM_TTY_KLUDGE
 654         /*
 655          * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
 656          * sshd doesn't set the tty until too late in the auth process and
 657          * may not even set one (for tty-less connections)
 658          */
 659         debug("PAM: setting PAM_TTY to \"ssh\"");
 660         sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
 661         if (sshpam_err != PAM_SUCCESS) {
 662                 pam_end(sshpam_handle, sshpam_err);
 663                 sshpam_handle = NULL;
 664                 return (-1);
 665         }
 666 #endif
 667         return (0);
 668 }
 669
 670 static void *
 671 sshpam_init_ctx(Authctxt *authctxt)
 672 {
 673         struct pam_ctxt *ctxt;
 674         int socks[2];
 675
 676         debug3("PAM: %s entering", __func__);
 677         /*
 678          * Refuse to start if we don't have PAM enabled or do_pam_account
 679          * has previously failed.
 680          */
 681         if (!options.use_pam || sshpam_account_status == 0)
 682                 return NULL;
 683
 684         /* Initialize PAM */
 685         if (sshpam_init(authctxt) == -1) {
 686                 error("PAM: initialization failed");
 687                 return (NULL);
 688         }
 689
 690         ctxt = xmalloc(sizeof *ctxt);
 691         memset(ctxt, 0, sizeof(*ctxt));
 692
 693         /* Start the authentication thread */
 694         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
 695                 error("PAM: failed create sockets: %s", strerror(errno));
 696                 xfree(ctxt);
 697                 return (NULL);
 698         }
 699         ctxt->pam_psock = socks[0];
 700         ctxt->pam_csock = socks[1];
 701         if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
 702                 error("PAM: failed to start authentication thread: %s",
 703                     strerror(errno));
 704                 close(socks[0]);
 705                 close(socks[1]);
 706                 xfree(ctxt);
 707                 return (NULL);
 708         }
 709         cleanup_ctxt = ctxt;
 710         return (ctxt);
 711 }
 712
 713 static int
 714 sshpam_query(void *ctx, char **name, char **info,
 715     u_int *num, char ***prompts, u_int **echo_on)
 716 {
 717         Buffer buffer;
 718         struct pam_ctxt *ctxt = ctx;
 719         size_t plen;
 720         u_char type;
 721         char *msg;
 722         size_t len, mlen;
 723
 724         debug3("PAM: %s entering", __func__);
 725         buffer_init(&buffer);
 726         *name = xstrdup("");
 727         *info = xstrdup("");
 728         *prompts = xmalloc(sizeof(char *));
 729         **prompts = NULL;
 730         plen = 0;
 731         *echo_on = xmalloc(sizeof(u_int));
 732         while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
 733                 type = buffer_get_char(&buffer);
 734                 msg = buffer_get_string(&buffer, NULL);
 735                 mlen = strlen(msg);
 736                 switch (type) {
 737                 case PAM_PROMPT_ECHO_ON:
 738                 case PAM_PROMPT_ECHO_OFF:
 739                         *num = 1;
 740                         len = plen + mlen + 1;
 741                         **prompts = xrealloc(**prompts, 1, len);
 742                         strlcpy(**prompts + plen, msg, len - plen);
 743                         plen += mlen;
 744                         **echo_on = (type == PAM_PROMPT_ECHO_ON);
 745                         xfree(msg);
 746                         return (0);
 747                 case PAM_ERROR_MSG:
 748                 case PAM_TEXT_INFO:
 749                         /* accumulate messages */
 750                         len = plen + mlen + 2;
 751                         **prompts = xrealloc(**prompts, 1, len);
 752                         strlcpy(**prompts + plen, msg, len - plen);
 753                         plen += mlen;
 754                         strlcat(**prompts + plen, "\n", len - plen);
 755                         plen++;
 756                         xfree(msg);
 757                         break;
 758                 case PAM_ACCT_EXPIRED:
 759                         sshpam_account_status = 0;
 760                         /* FALLTHROUGH */
 761                 case PAM_AUTH_ERR:
 762                         debug3("PAM: %s", pam_strerror(sshpam_handle, type));
 763                         if (**prompts != NULL && strlen(**prompts) != 0) {
 764                                 *info = **prompts;
 765                                 **prompts = NULL;
 766                                 *num = 0;
 767                                 **echo_on = 0;
 768                                 ctxt->pam_done = -1;
 769                                 xfree(msg);
 770                                 return 0;
 771                         }
 772                         /* FALLTHROUGH */
 773                 case PAM_SUCCESS:
 774                         if (**prompts != NULL) {
 775                                 /* drain any accumulated messages */
 776                                 debug("PAM: %s", **prompts);
 777                                 buffer_append(&loginmsg, **prompts,
 778                                     strlen(**prompts));
 779                                 xfree(**prompts);
 780                                 **prompts = NULL;
 781                         }
 782                         if (type == PAM_SUCCESS) {
 783                                 if (!sshpam_authctxt->valid ||
 784                                     (sshpam_authctxt->pw->pw_uid == 0 &&
 785                                     options.permit_root_login != PERMIT_YES))
 786                                         fatal("Internal error: PAM auth "
 787                                             "succeeded when it should have "
 788                                             "failed");
 789                                 import_environments(&buffer);
 790                                 *num = 0;
 791                                 **echo_on = 0;
 792                                 ctxt->pam_done = 1;
 793                                 xfree(msg);
 794                                 return (0);
 795                         }
 796                         error("PAM: %s for %s%.100s from %.100s", msg,
 797                             sshpam_authctxt->valid ? "" : "illegal user ",
 798                             sshpam_authctxt->user,
 799                             get_remote_name_or_ip(utmp_len, options.use_dns));
 800                         /* FALLTHROUGH */
 801                 default:
 802                         *num = 0;
 803                         **echo_on = 0;
 804                         xfree(msg);
 805                         ctxt->pam_done = -1;
 806                         return (-1);
 807                 }
 808         }
 809         return (-1);
 810 }
 811
 812 /* XXX - see also comment in auth-chall.c:verify_response */
 813 static int
 814 sshpam_respond(void *ctx, u_int num, char **resp)
 815 {
 816         Buffer buffer;
 817         struct pam_ctxt *ctxt = ctx;
 818
 819         debug2("PAM: %s entering, %u responses", __func__, num);
 820         switch (ctxt->pam_done) {
 821         case 1:
 822                 sshpam_authenticated = 1;
 823                 return (0);
 824         case 0:
 825                 break;
 826         default:
 827                 return (-1);
 828         }
 829         if (num != 1) {
 830                 error("PAM: expected one response, got %u", num);
 831                 return (-1);
 832         }
 833         buffer_init(&buffer);
 834         if (sshpam_authctxt->valid &&
 835             (sshpam_authctxt->pw->pw_uid != 0 ||
 836             options.permit_root_login == PERMIT_YES))
 837                 buffer_put_cstring(&buffer, *resp);
 838         else
 839                 buffer_put_cstring(&buffer, badpw);
 840         if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
 841                 buffer_free(&buffer);
 842                 return (-1);
 843         }
 844         buffer_free(&buffer);
 845         return (1);
 846 }
 847
 848 static void
 849 sshpam_free_ctx(void *ctxtp)
 850 {
 851         struct pam_ctxt *ctxt = ctxtp;
 852
 853         debug3("PAM: %s entering", __func__);
 854         sshpam_thread_cleanup();
 855         xfree(ctxt);
 856         /*
 857          * We don't call sshpam_cleanup() here because we may need the PAM
 858          * handle at a later stage, e.g. when setting up a session.  It's
 859          * still on the cleanup list, so pam_end() *will* be called before
 860          * the server process terminates.
 861          */
 862 }
 863
 864 KbdintDevice sshpam_device = {
 865         "pam",
 866         sshpam_init_ctx,
 867         sshpam_query,
 868         sshpam_respond,
 869         sshpam_free_ctx
 870 };
 871
 872 KbdintDevice mm_sshpam_device = {
 873         "pam",
 874         mm_sshpam_init_ctx,
 875         mm_sshpam_query,
 876         mm_sshpam_respond,
 877         mm_sshpam_free_ctx
 878 };
 879
 880 /*
 881  * This replaces auth-pam.c
 882  */
 883 void
 884 start_pam(Authctxt *authctxt)
 885 {
 886         if (!options.use_pam)
 887                 fatal("PAM: initialisation requested when UsePAM=no");
 888
 889         if (sshpam_init(authctxt) == -1)
 890                 fatal("PAM: initialisation failed");
 891 }
 892
 893 void
 894 finish_pam(void)
 895 {
 896         sshpam_cleanup();
 897 }
 898
 899 u_int
 900 do_pam_account(void)
 901 {
 902         debug("%s: called", __func__);
 903         if (sshpam_account_status != -1)
 904                 return (sshpam_account_status);
 905
 906         sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
 907         debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
 908             pam_strerror(sshpam_handle, sshpam_err));
 909
 910         if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
 911                 sshpam_account_status = 0;
 912                 return (sshpam_account_status);
 913         }
 914
 915         if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
 916                 sshpam_password_change_required(1);
 917
 918         sshpam_account_status = 1;
 919         return (sshpam_account_status);
 920 }
 921
 922 void
 923 do_pam_set_tty(const char *tty)
 924 {
 925         if (tty != NULL) {
 926                 debug("PAM: setting PAM_TTY to \"%s\"", tty);
 927                 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
 928                 if (sshpam_err != PAM_SUCCESS)
 929                         fatal("PAM: failed to set PAM_TTY: %s",
 930                             pam_strerror(sshpam_handle, sshpam_err));
 931         }
 932 }
 933
 934 void
 935 do_pam_setcred(int init)
 936 {
 937         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 938             (const void *)&store_conv);
 939         if (sshpam_err != PAM_SUCCESS)
 940                 fatal("PAM: failed to set PAM_CONV: %s",
 941                     pam_strerror(sshpam_handle, sshpam_err));
 942         if (init) {
 943                 debug("PAM: establishing credentials");
 944                 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
 945         } else {
 946                 debug("PAM: reinitializing credentials");
 947                 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
 948         }
 949         if (sshpam_err == PAM_SUCCESS) {
 950                 sshpam_cred_established = 1;
 951                 return;
 952         }
 953         if (sshpam_authenticated)
 954                 fatal("PAM: pam_setcred(): %s",
 955                     pam_strerror(sshpam_handle, sshpam_err));
 956         else
 957                 debug("PAM: pam_setcred(): %s",
 958                     pam_strerror(sshpam_handle, sshpam_err));
 959 }
 960
 961 static int
 962 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
 963     struct pam_response **resp, void *data)
 964 {
 965         char input[PAM_MAX_MSG_SIZE];
 966         struct pam_response *reply;
 967         int i;
 968
 969         debug3("PAM: %s called with %d messages", __func__, n);
 970
 971         *resp = NULL;
 972
 973         if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
 974                 return (PAM_CONV_ERR);
 975
 976         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 977                 return (PAM_CONV_ERR);
 978
 979         for (i = 0; i < n; ++i) {
 980                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 981                 case PAM_PROMPT_ECHO_OFF:
 982                         reply[i].resp =
 983                             read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
 984                             RP_ALLOW_STDIN);
 985                         reply[i].resp_retcode = PAM_SUCCESS;
 986                         break;
 987                 case PAM_PROMPT_ECHO_ON:
 988                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 989                         fgets(input, sizeof input, stdin);
 990                         if ((reply[i].resp = strdup(input)) == NULL)
 991                                 goto fail;
 992                         reply[i].resp_retcode = PAM_SUCCESS;
 993                         break;
 994                 case PAM_ERROR_MSG:
 995                 case PAM_TEXT_INFO:
 996                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 997                         reply[i].resp_retcode = PAM_SUCCESS;
 998                         break;
 999                 default:
1000                         goto fail;
1001                 }
1002         }
1003         *resp = reply;
1004         return (PAM_SUCCESS);
1005
1006  fail:
1007         for(i = 0; i < n; i++) {
1008                 if (reply[i].resp != NULL)
1009                         xfree(reply[i].resp);
1010         }
1011         xfree(reply);
1012         return (PAM_CONV_ERR);
1013 }
1014
1015 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
1016
1017 /*
1018  * XXX this should be done in the authentication phase, but ssh1 doesn't
1019  * support that
1020  */
1021 void
1022 do_pam_chauthtok(void)
1023 {
1024         if (use_privsep)
1025                 fatal("Password expired (unable to change with privsep)");
1026         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1027             (const void *)&tty_conv);
1028         if (sshpam_err != PAM_SUCCESS)
1029                 fatal("PAM: failed to set PAM_CONV: %s",
1030                     pam_strerror(sshpam_handle, sshpam_err));
1031         debug("PAM: changing password");
1032         sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
1033         if (sshpam_err != PAM_SUCCESS)
1034                 fatal("PAM: pam_chauthtok(): %s",
1035                     pam_strerror(sshpam_handle, sshpam_err));
1036 }
1037
1038 void
1039 do_pam_session(void)
1040 {
1041         debug3("PAM: opening session");
1042         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1043             (const void *)&store_conv);
1044         if (sshpam_err != PAM_SUCCESS)
1045                 fatal("PAM: failed to set PAM_CONV: %s",
1046                     pam_strerror(sshpam_handle, sshpam_err));
1047         sshpam_err = pam_open_session(sshpam_handle, 0);
1048         if (sshpam_err == PAM_SUCCESS)
1049                 sshpam_session_open = 1;
1050         else {
1051                 sshpam_session_open = 0;
1052                 disable_forwarding();
1053                 error("PAM: pam_open_session(): %s",
1054                     pam_strerror(sshpam_handle, sshpam_err));
1055         }
1056
1057 }
1058
1059 int
1060 is_pam_session_open(void)
1061 {
1062         return sshpam_session_open;
1063 }
1064
1065 /*
1066  * Set a PAM environment string. We need to do this so that the session
1067  * modules can handle things like Kerberos/GSI credentials that appear
1068  * during the ssh authentication process.
1069  */
1070 int
1071 do_pam_putenv(char *name, char *value)
1072 {
1073         int ret = 1;
1074 #ifdef HAVE_PAM_PUTENV
1075         char *compound;
1076         size_t len;
1077
1078         len = strlen(name) + strlen(value) + 2;
1079         compound = xmalloc(len);
1080
1081         snprintf(compound, len, "%s=%s", name, value);
1082         ret = pam_putenv(sshpam_handle, compound);
1083         xfree(compound);
1084 #endif
1085
1086         return (ret);
1087 }
1088
1089 char **
1090 fetch_pam_child_environment(void)
1091 {
1092         return sshpam_env;
1093 }
1094
1095 char **
1096 fetch_pam_environment(void)
1097 {
1098         return (pam_getenvlist(sshpam_handle));
1099 }
1100
1101 void
1102 free_pam_environment(char **env)
1103 {
1104         char **envp;
1105
1106         if (env == NULL)
1107                 return;
1108
1109         for (envp = env; *envp; envp++)
1110                 xfree(*envp);
1111         xfree(env);
1112 }
1113
1114 /*
1115  * "Blind" conversation function for password authentication.  Assumes that
1116  * echo-off prompts are for the password and stores messages for later
1117  * display.
1118  */
1119 static int
1120 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1121     struct pam_response **resp, void *data)
1122 {
1123         struct pam_response *reply;
1124         int i;
1125         size_t len;
1126
1127         debug3("PAM: %s called with %d messages", __func__, n);
1128
1129         *resp = NULL;
1130
1131         if (n <= 0 || n > PAM_MAX_NUM_MSG)
1132                 return (PAM_CONV_ERR);
1133
1134         if ((reply = malloc(n * sizeof(*reply))) == NULL)
1135                 return (PAM_CONV_ERR);
1136         memset(reply, 0, n * sizeof(*reply));
1137
1138         for (i = 0; i < n; ++i) {
1139                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1140                 case PAM_PROMPT_ECHO_OFF:
1141                         if (sshpam_password == NULL)
1142                                 goto fail;
1143                         if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1144                                 goto fail;
1145                         reply[i].resp_retcode = PAM_SUCCESS;
1146                         break;
1147                 case PAM_ERROR_MSG:
1148                 case PAM_TEXT_INFO:
1149                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1150                         if (len > 0) {
1151                                 buffer_append(&loginmsg,
1152                                     PAM_MSG_MEMBER(msg, i, msg), len);
1153                                 buffer_append(&loginmsg, "\n", 1);
1154                         }
1155                         if ((reply[i].resp = strdup("")) == NULL)
1156                                 goto fail;
1157                         reply[i].resp_retcode = PAM_SUCCESS;
1158                         break;
1159                 default:
1160                         goto fail;
1161                 }
1162         }
1163         *resp = reply;
1164         return (PAM_SUCCESS);
1165
1166  fail:
1167         for(i = 0; i < n; i++) {
1168                 if (reply[i].resp != NULL)
1169                         xfree(reply[i].resp);
1170         }
1171         xfree(reply);
1172         return (PAM_CONV_ERR);
1173 }
1174
1175 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1176
1177 /*
1178  * Attempt password authentication via PAM
1179  */
1180 int
1181 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1182 {
1183         int flags = (options.permit_empty_passwd == 0 ?
1184             PAM_DISALLOW_NULL_AUTHTOK : 0);
1185
1186         if (!options.use_pam || sshpam_handle == NULL)
1187                 fatal("PAM: %s called when PAM disabled or failed to "
1188                     "initialise.", __func__);
1189
1190         sshpam_password = password;
1191         sshpam_authctxt = authctxt;
1192
1193         /*
1194          * If the user logging in is invalid, or is root but is not permitted
1195          * by PermitRootLogin, use an invalid password to prevent leaking
1196          * information via timing (eg if the PAM config has a delay on fail).
1197          */
1198         if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1199             options.permit_root_login != PERMIT_YES))
1200                 sshpam_password = badpw;
1201
1202         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1203             (const void *)&passwd_conv);
1204         if (sshpam_err != PAM_SUCCESS)
1205                 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1206                     pam_strerror(sshpam_handle, sshpam_err));
1207
1208         sshpam_err = pam_authenticate(sshpam_handle, flags);
1209         sshpam_password = NULL;
1210         if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1211                 debug("PAM: password authentication accepted for %.100s",
1212                     authctxt->user);
1213                 return 1;
1214         } else {
1215                 debug("PAM: password authentication failed for %.100s: %s",
1216                     authctxt->valid ? authctxt->user : "an illegal user",
1217                     pam_strerror(sshpam_handle, sshpam_err));
1218                 return 0;
1219         }
1220 }
1221 #endif /* USE_PAM */