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
 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                 sigdie("PAM: authentication thread exited unexpectedly");
 166         if (WEXITSTATUS(sshpam_thread_status) != 0)
 167                 sigdie("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                 free(reply[i].resp);
 417         }
 418         free(reply);
 419         buffer_free(&buffer);
 420         return (PAM_CONV_ERR);
 421 }
 422
 423 /*
 424  * Authentication thread.
 425  */
 426 static void *
 427 sshpam_thread(void *ctxtp)
 428 {
 429         struct pam_ctxt *ctxt = ctxtp;
 430         Buffer buffer;
 431         struct pam_conv sshpam_conv;
 432         int flags = (options.permit_empty_passwd == 0 ?
 433             PAM_DISALLOW_NULL_AUTHTOK : 0);
 434 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 435         extern char **environ;
 436         char **env_from_pam;
 437         u_int i;
 438         const char *pam_user;
 439         const char **ptr_pam_user = &pam_user;
 440         char *tz = getenv("TZ");
 441
 442         sshpam_err = pam_get_item(sshpam_handle, PAM_USER,
 443             (sshpam_const void **)ptr_pam_user);
 444         if (sshpam_err != PAM_SUCCESS)
 445                 goto auth_fail;
 446
 447         environ[0] = NULL;
 448         if (tz != NULL)
 449                 if (setenv("TZ", tz, 1) == -1)
 450                         error("PAM: could not set TZ environment: %s",
 451                             strerror(errno));
 452
 453         if (sshpam_authctxt != NULL) {
 454                 setproctitle("%s [pam]",
 455                     sshpam_authctxt->valid ? pam_user : "unknown");
 456         }
 457 #endif
 458
 459         sshpam_conv.conv = sshpam_thread_conv;
 460         sshpam_conv.appdata_ptr = ctxt;
 461
 462         if (sshpam_authctxt == NULL)
 463                 fatal("%s: PAM authctxt not initialized", __func__);
 464
 465         buffer_init(&buffer);
 466         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 467             (const void *)&sshpam_conv);
 468         if (sshpam_err != PAM_SUCCESS)
 469                 goto auth_fail;
 470         sshpam_err = pam_authenticate(sshpam_handle, flags);
 471         if (sshpam_err != PAM_SUCCESS)
 472                 goto auth_fail;
 473
 474         if (compat20) {
 475                 if (!do_pam_account()) {
 476                         sshpam_err = PAM_ACCT_EXPIRED;
 477                         goto auth_fail;
 478                 }
 479                 if (sshpam_authctxt->force_pwchange) {
 480                         sshpam_err = pam_chauthtok(sshpam_handle,
 481                             PAM_CHANGE_EXPIRED_AUTHTOK);
 482                         if (sshpam_err != PAM_SUCCESS)
 483                                 goto auth_fail;
 484                         sshpam_password_change_required(0);
 485                 }
 486         }
 487
 488         buffer_put_cstring(&buffer, "OK");
 489
 490 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 491         /* Export variables set by do_pam_account */
 492         buffer_put_int(&buffer, sshpam_account_status);
 493         buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);
 494
 495         /* Export any environment strings set in child */
 496         for(i = 0; environ[i] != NULL; i++)
 497                 ; /* Count */
 498         buffer_put_int(&buffer, i);
 499         for(i = 0; environ[i] != NULL; i++)
 500                 buffer_put_cstring(&buffer, environ[i]);
 501
 502         /* Export any environment strings set by PAM in child */
 503         env_from_pam = pam_getenvlist(sshpam_handle);
 504         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 505                 ; /* Count */
 506         buffer_put_int(&buffer, i);
 507         for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
 508                 buffer_put_cstring(&buffer, env_from_pam[i]);
 509 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */
 510
 511         /* XXX - can't do much about an error here */
 512         ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
 513         buffer_free(&buffer);
 514         pthread_exit(NULL);
 515
 516  auth_fail:
 517         buffer_put_cstring(&buffer,
 518             pam_strerror(sshpam_handle, sshpam_err));
 519         /* XXX - can't do much about an error here */
 520         if (sshpam_err == PAM_ACCT_EXPIRED)
 521                 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, &buffer);
 522         else
 523                 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
 524         buffer_free(&buffer);
 525         pthread_exit(NULL);
 526
 527         return (NULL); /* Avoid warning for non-pthread case */
 528 }
 529
 530 void
 531 sshpam_thread_cleanup(void)
 532 {
 533         struct pam_ctxt *ctxt = cleanup_ctxt;
 534
 535         debug3("PAM: %s entering", __func__);
 536         if (ctxt != NULL && ctxt->pam_thread != 0) {
 537                 pthread_cancel(ctxt->pam_thread);
 538                 pthread_join(ctxt->pam_thread, NULL);
 539                 close(ctxt->pam_psock);
 540                 close(ctxt->pam_csock);
 541                 memset(ctxt, 0, sizeof(*ctxt));
 542                 cleanup_ctxt = NULL;
 543         }
 544 }
 545
 546 static int
 547 sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
 548     struct pam_response **resp, void *data)
 549 {
 550         debug3("PAM: %s entering, %d messages", __func__, n);
 551         return (PAM_CONV_ERR);
 552 }
 553
 554 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
 555
 556 static int
 557 sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
 558     struct pam_response **resp, void *data)
 559 {
 560         struct pam_response *reply;
 561         int i;
 562         size_t len;
 563
 564         debug3("PAM: %s called with %d messages", __func__, n);
 565         *resp = NULL;
 566
 567         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 568                 return (PAM_CONV_ERR);
 569
 570         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 571                 return (PAM_CONV_ERR);
 572
 573         for (i = 0; i < n; ++i) {
 574                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 575                 case PAM_ERROR_MSG:
 576                 case PAM_TEXT_INFO:
 577                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
 578                         buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
 579                         buffer_append(&loginmsg, "\n", 1 );
 580                         reply[i].resp_retcode = PAM_SUCCESS;
 581                         break;
 582                 default:
 583                         goto fail;
 584                 }
 585         }
 586         *resp = reply;
 587         return (PAM_SUCCESS);
 588
 589  fail:
 590         for(i = 0; i < n; i++) {
 591                 free(reply[i].resp);
 592         }
 593         free(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         if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor()))
 603                 return;
 604         debug("PAM: cleanup");
 605         pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 606         if (sshpam_session_open) {
 607                 debug("PAM: closing session");
 608                 pam_close_session(sshpam_handle, PAM_SILENT);
 609                 sshpam_session_open = 0;
 610         }
 611         if (sshpam_cred_established) {
 612                 debug("PAM: deleting credentials");
 613                 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
 614                 sshpam_cred_established = 0;
 615         }
 616         sshpam_authenticated = 0;
 617         pam_end(sshpam_handle, sshpam_err);
 618         sshpam_handle = NULL;
 619 }
 620
 621 static int
 622 sshpam_init(Authctxt *authctxt)
 623 {
 624         extern char *__progname;
 625         const char *pam_rhost, *pam_user, *user = authctxt->user;
 626         const char **ptr_pam_user = &pam_user;
 627
 628         if (sshpam_handle != NULL) {
 629                 /* We already have a PAM context; check if the user matches */
 630                 sshpam_err = pam_get_item(sshpam_handle,
 631                     PAM_USER, (sshpam_const void **)ptr_pam_user);
 632                 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
 633                         return (0);
 634                 pam_end(sshpam_handle, sshpam_err);
 635                 sshpam_handle = NULL;
 636         }
 637         debug("PAM: initializing for \"%s\"", user);
 638         sshpam_err =
 639             pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
 640         sshpam_authctxt = authctxt;
 641
 642         if (sshpam_err != PAM_SUCCESS) {
 643                 pam_end(sshpam_handle, sshpam_err);
 644                 sshpam_handle = NULL;
 645                 return (-1);
 646         }
 647         pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
 648         debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
 649         sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
 650         if (sshpam_err != PAM_SUCCESS) {
 651                 pam_end(sshpam_handle, sshpam_err);
 652                 sshpam_handle = NULL;
 653                 return (-1);
 654         }
 655 #ifdef PAM_TTY_KLUDGE
 656         /*
 657          * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
 658          * sshd doesn't set the tty until too late in the auth process and
 659          * may not even set one (for tty-less connections)
 660          */
 661         debug("PAM: setting PAM_TTY to \"ssh\"");
 662         sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
 663         if (sshpam_err != PAM_SUCCESS) {
 664                 pam_end(sshpam_handle, sshpam_err);
 665                 sshpam_handle = NULL;
 666                 return (-1);
 667         }
 668 #endif
 669         return (0);
 670 }
 671
 672 static void *
 673 sshpam_init_ctx(Authctxt *authctxt)
 674 {
 675         struct pam_ctxt *ctxt;
 676         int socks[2];
 677
 678         debug3("PAM: %s entering", __func__);
 679         /*
 680          * Refuse to start if we don't have PAM enabled or do_pam_account
 681          * has previously failed.
 682          */
 683         if (!options.use_pam || sshpam_account_status == 0)
 684                 return NULL;
 685
 686         /* Initialize PAM */
 687         if (sshpam_init(authctxt) == -1) {
 688                 error("PAM: initialization failed");
 689                 return (NULL);
 690         }
 691
 692         ctxt = xcalloc(1, sizeof *ctxt);
 693
 694         /* Start the authentication thread */
 695         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
 696                 error("PAM: failed create sockets: %s", strerror(errno));
 697                 free(ctxt);
 698                 return (NULL);
 699         }
 700         ctxt->pam_psock = socks[0];
 701         ctxt->pam_csock = socks[1];
 702         if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
 703                 error("PAM: failed to start authentication thread: %s",
 704                     strerror(errno));
 705                 close(socks[0]);
 706                 close(socks[1]);
 707                 free(ctxt);
 708                 return (NULL);
 709         }
 710         cleanup_ctxt = ctxt;
 711         return (ctxt);
 712 }
 713
 714 static int
 715 sshpam_query(void *ctx, char **name, char **info,
 716     u_int *num, char ***prompts, u_int **echo_on)
 717 {
 718         Buffer buffer;
 719         struct pam_ctxt *ctxt = ctx;
 720         size_t plen;
 721         u_char type;
 722         char *msg;
 723         size_t len, mlen;
 724
 725         debug3("PAM: %s entering", __func__);
 726         buffer_init(&buffer);
 727         *name = xstrdup("");
 728         *info = xstrdup("");
 729         *prompts = xmalloc(sizeof(char *));
 730         **prompts = NULL;
 731         plen = 0;
 732         *echo_on = xmalloc(sizeof(u_int));
 733         while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
 734                 type = buffer_get_char(&buffer);
 735                 msg = buffer_get_string(&buffer, NULL);
 736                 mlen = strlen(msg);
 737                 switch (type) {
 738                 case PAM_PROMPT_ECHO_ON:
 739                 case PAM_PROMPT_ECHO_OFF:
 740                         *num = 1;
 741                         len = plen + mlen + 1;
 742                         **prompts = xreallocarray(**prompts, 1, len);
 743                         strlcpy(**prompts + plen, msg, len - plen);
 744                         plen += mlen;
 745                         **echo_on = (type == PAM_PROMPT_ECHO_ON);
 746                         free(msg);
 747                         return (0);
 748                 case PAM_ERROR_MSG:
 749                 case PAM_TEXT_INFO:
 750                         /* accumulate messages */
 751                         len = plen + mlen + 2;
 752                         **prompts = xreallocarray(**prompts, 1, len);
 753                         strlcpy(**prompts + plen, msg, len - plen);
 754                         plen += mlen;
 755                         strlcat(**prompts + plen, "\n", len - plen);
 756                         plen++;
 757                         free(msg);
 758                         break;
 759                 case PAM_ACCT_EXPIRED:
 760                         sshpam_account_status = 0;
 761                         /* FALLTHROUGH */
 762                 case PAM_AUTH_ERR:
 763                         debug3("PAM: %s", pam_strerror(sshpam_handle, type));
 764                         if (**prompts != NULL && strlen(**prompts) != 0) {
 765                                 *info = **prompts;
 766                                 **prompts = NULL;
 767                                 *num = 0;
 768                                 **echo_on = 0;
 769                                 ctxt->pam_done = -1;
 770                                 free(msg);
 771                                 return 0;
 772                         }
 773                         /* FALLTHROUGH */
 774                 case PAM_SUCCESS:
 775                         if (**prompts != NULL) {
 776                                 /* drain any accumulated messages */
 777                                 debug("PAM: %s", **prompts);
 778                                 buffer_append(&loginmsg, **prompts,
 779                                     strlen(**prompts));
 780                                 free(**prompts);
 781                                 **prompts = NULL;
 782                         }
 783                         if (type == PAM_SUCCESS) {
 784                                 if (!sshpam_authctxt->valid ||
 785                                     (sshpam_authctxt->pw->pw_uid == 0 &&
 786                                     options.permit_root_login != PERMIT_YES))
 787                                         fatal("Internal error: PAM auth "
 788                                             "succeeded when it should have "
 789                                             "failed");
 790                                 import_environments(&buffer);
 791                                 *num = 0;
 792                                 **echo_on = 0;
 793                                 ctxt->pam_done = 1;
 794                                 free(msg);
 795                                 return (0);
 796                         }
 797                         error("PAM: %s for %s%.100s from %.100s", msg,
 798                             sshpam_authctxt->valid ? "" : "illegal user ",
 799                             sshpam_authctxt->user,
 800                             get_remote_name_or_ip(utmp_len, options.use_dns));
 801                         /* FALLTHROUGH */
 802                 default:
 803                         *num = 0;
 804                         **echo_on = 0;
 805                         free(msg);
 806                         ctxt->pam_done = -1;
 807                         return (-1);
 808                 }
 809         }
 810         return (-1);
 811 }
 812
 813 /* XXX - see also comment in auth-chall.c:verify_response */
 814 static int
 815 sshpam_respond(void *ctx, u_int num, char **resp)
 816 {
 817         Buffer buffer;
 818         struct pam_ctxt *ctxt = ctx;
 819
 820         debug2("PAM: %s entering, %u responses", __func__, num);
 821         switch (ctxt->pam_done) {
 822         case 1:
 823                 sshpam_authenticated = 1;
 824                 return (0);
 825         case 0:
 826                 break;
 827         default:
 828                 return (-1);
 829         }
 830         if (num != 1) {
 831                 error("PAM: expected one response, got %u", num);
 832                 return (-1);
 833         }
 834         buffer_init(&buffer);
 835         if (sshpam_authctxt->valid &&
 836             (sshpam_authctxt->pw->pw_uid != 0 ||
 837             options.permit_root_login == PERMIT_YES))
 838                 buffer_put_cstring(&buffer, *resp);
 839         else
 840                 buffer_put_cstring(&buffer, badpw);
 841         if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
 842                 buffer_free(&buffer);
 843                 return (-1);
 844         }
 845         buffer_free(&buffer);
 846         return (1);
 847 }
 848
 849 static void
 850 sshpam_free_ctx(void *ctxtp)
 851 {
 852         struct pam_ctxt *ctxt = ctxtp;
 853
 854         debug3("PAM: %s entering", __func__);
 855         sshpam_thread_cleanup();
 856         free(ctxt);
 857         /*
 858          * We don't call sshpam_cleanup() here because we may need the PAM
 859          * handle at a later stage, e.g. when setting up a session.  It's
 860          * still on the cleanup list, so pam_end() *will* be called before
 861          * the server process terminates.
 862          */
 863 }
 864
 865 KbdintDevice sshpam_device = {
 866         "pam",
 867         sshpam_init_ctx,
 868         sshpam_query,
 869         sshpam_respond,
 870         sshpam_free_ctx
 871 };
 872
 873 KbdintDevice mm_sshpam_device = {
 874         "pam",
 875         mm_sshpam_init_ctx,
 876         mm_sshpam_query,
 877         mm_sshpam_respond,
 878         mm_sshpam_free_ctx
 879 };
 880
 881 /*
 882  * This replaces auth-pam.c
 883  */
 884 void
 885 start_pam(Authctxt *authctxt)
 886 {
 887         if (!options.use_pam)
 888                 fatal("PAM: initialisation requested when UsePAM=no");
 889
 890         if (sshpam_init(authctxt) == -1)
 891                 fatal("PAM: initialisation failed");
 892 }
 893
 894 void
 895 finish_pam(void)
 896 {
 897         sshpam_cleanup();
 898 }
 899
 900 u_int
 901 do_pam_account(void)
 902 {
 903         debug("%s: called", __func__);
 904         if (sshpam_account_status != -1)
 905                 return (sshpam_account_status);
 906
 907         sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
 908         debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
 909             pam_strerror(sshpam_handle, sshpam_err));
 910
 911         if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
 912                 sshpam_account_status = 0;
 913                 return (sshpam_account_status);
 914         }
 915
 916         if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
 917                 sshpam_password_change_required(1);
 918
 919         sshpam_account_status = 1;
 920         return (sshpam_account_status);
 921 }
 922
 923 void
 924 do_pam_set_tty(const char *tty)
 925 {
 926         if (tty != NULL) {
 927                 debug("PAM: setting PAM_TTY to \"%s\"", tty);
 928                 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
 929                 if (sshpam_err != PAM_SUCCESS)
 930                         fatal("PAM: failed to set PAM_TTY: %s",
 931                             pam_strerror(sshpam_handle, sshpam_err));
 932         }
 933 }
 934
 935 void
 936 do_pam_setcred(int init)
 937 {
 938         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 939             (const void *)&store_conv);
 940         if (sshpam_err != PAM_SUCCESS)
 941                 fatal("PAM: failed to set PAM_CONV: %s",
 942                     pam_strerror(sshpam_handle, sshpam_err));
 943         if (init) {
 944                 debug("PAM: establishing credentials");
 945                 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
 946         } else {
 947                 debug("PAM: reinitializing credentials");
 948                 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
 949         }
 950         if (sshpam_err == PAM_SUCCESS) {
 951                 sshpam_cred_established = 1;
 952                 return;
 953         }
 954         if (sshpam_authenticated)
 955                 fatal("PAM: pam_setcred(): %s",
 956                     pam_strerror(sshpam_handle, sshpam_err));
 957         else
 958                 debug("PAM: pam_setcred(): %s",
 959                     pam_strerror(sshpam_handle, sshpam_err));
 960 }
 961
 962 static int
 963 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
 964     struct pam_response **resp, void *data)
 965 {
 966         char input[PAM_MAX_MSG_SIZE];
 967         struct pam_response *reply;
 968         int i;
 969
 970         debug3("PAM: %s called with %d messages", __func__, n);
 971
 972         *resp = NULL;
 973
 974         if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
 975                 return (PAM_CONV_ERR);
 976
 977         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 978                 return (PAM_CONV_ERR);
 979
 980         for (i = 0; i < n; ++i) {
 981                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 982                 case PAM_PROMPT_ECHO_OFF:
 983                         reply[i].resp =
 984                             read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
 985                             RP_ALLOW_STDIN);
 986                         reply[i].resp_retcode = PAM_SUCCESS;
 987                         break;
 988                 case PAM_PROMPT_ECHO_ON:
 989                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 990                         if (fgets(input, sizeof input, stdin) == NULL)
 991                                 input[0] = '\0';
 992                         if ((reply[i].resp = strdup(input)) == NULL)
 993                                 goto fail;
 994                         reply[i].resp_retcode = PAM_SUCCESS;
 995                         break;
 996                 case PAM_ERROR_MSG:
 997                 case PAM_TEXT_INFO:
 998                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
 999                         reply[i].resp_retcode = PAM_SUCCESS;
1000                         break;
1001                 default:
1002                         goto fail;
1003                 }
1004         }
1005         *resp = reply;
1006         return (PAM_SUCCESS);
1007
1008  fail:
1009         for(i = 0; i < n; i++) {
1010                 free(reply[i].resp);
1011         }
1012         free(reply);
1013         return (PAM_CONV_ERR);
1014 }
1015
1016 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
1017
1018 /*
1019  * XXX this should be done in the authentication phase, but ssh1 doesn't
1020  * support that
1021  */
1022 void
1023 do_pam_chauthtok(void)
1024 {
1025         if (use_privsep)
1026                 fatal("Password expired (unable to change with privsep)");
1027         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1028             (const void *)&tty_conv);
1029         if (sshpam_err != PAM_SUCCESS)
1030                 fatal("PAM: failed to set PAM_CONV: %s",
1031                     pam_strerror(sshpam_handle, sshpam_err));
1032         debug("PAM: changing password");
1033         sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
1034         if (sshpam_err != PAM_SUCCESS)
1035                 fatal("PAM: pam_chauthtok(): %s",
1036                     pam_strerror(sshpam_handle, sshpam_err));
1037 }
1038
1039 void
1040 do_pam_session(void)
1041 {
1042         debug3("PAM: opening session");
1043         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1044             (const void *)&store_conv);
1045         if (sshpam_err != PAM_SUCCESS)
1046                 fatal("PAM: failed to set PAM_CONV: %s",
1047                     pam_strerror(sshpam_handle, sshpam_err));
1048         sshpam_err = pam_open_session(sshpam_handle, 0);
1049         if (sshpam_err == PAM_SUCCESS)
1050                 sshpam_session_open = 1;
1051         else {
1052                 sshpam_session_open = 0;
1053                 disable_forwarding();
1054                 error("PAM: pam_open_session(): %s",
1055                     pam_strerror(sshpam_handle, sshpam_err));
1056         }
1057
1058 }
1059
1060 int
1061 is_pam_session_open(void)
1062 {
1063         return sshpam_session_open;
1064 }
1065
1066 /*
1067  * Set a PAM environment string. We need to do this so that the session
1068  * modules can handle things like Kerberos/GSI credentials that appear
1069  * during the ssh authentication process.
1070  */
1071 int
1072 do_pam_putenv(char *name, char *value)
1073 {
1074         int ret = 1;
1075 #ifdef HAVE_PAM_PUTENV
1076         char *compound;
1077         size_t len;
1078
1079         len = strlen(name) + strlen(value) + 2;
1080         compound = xmalloc(len);
1081
1082         snprintf(compound, len, "%s=%s", name, value);
1083         ret = pam_putenv(sshpam_handle, compound);
1084         free(compound);
1085 #endif
1086
1087         return (ret);
1088 }
1089
1090 char **
1091 fetch_pam_child_environment(void)
1092 {
1093         return sshpam_env;
1094 }
1095
1096 char **
1097 fetch_pam_environment(void)
1098 {
1099         return (pam_getenvlist(sshpam_handle));
1100 }
1101
1102 void
1103 free_pam_environment(char **env)
1104 {
1105         char **envp;
1106
1107         if (env == NULL)
1108                 return;
1109
1110         for (envp = env; *envp; envp++)
1111                 free(*envp);
1112         free(env);
1113 }
1114
1115 /*
1116  * "Blind" conversation function for password authentication.  Assumes that
1117  * echo-off prompts are for the password and stores messages for later
1118  * display.
1119  */
1120 static int
1121 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1122     struct pam_response **resp, void *data)
1123 {
1124         struct pam_response *reply;
1125         int i;
1126         size_t len;
1127
1128         debug3("PAM: %s called with %d messages", __func__, n);
1129
1130         *resp = NULL;
1131
1132         if (n <= 0 || n > PAM_MAX_NUM_MSG)
1133                 return (PAM_CONV_ERR);
1134
1135         if ((reply = calloc(n, sizeof(*reply))) == NULL)
1136                 return (PAM_CONV_ERR);
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                 free(reply[i].resp);
1169         }
1170         free(reply);
1171         return (PAM_CONV_ERR);
1172 }
1173
1174 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1175
1176 /*
1177  * Attempt password authentication via PAM
1178  */
1179 int
1180 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1181 {
1182         int flags = (options.permit_empty_passwd == 0 ?
1183             PAM_DISALLOW_NULL_AUTHTOK : 0);
1184
1185         if (!options.use_pam || sshpam_handle == NULL)
1186                 fatal("PAM: %s called when PAM disabled or failed to "
1187                     "initialise.", __func__);
1188
1189         sshpam_password = password;
1190         sshpam_authctxt = authctxt;
1191
1192         /*
1193          * If the user logging in is invalid, or is root but is not permitted
1194          * by PermitRootLogin, use an invalid password to prevent leaking
1195          * information via timing (eg if the PAM config has a delay on fail).
1196          */
1197         if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1198             options.permit_root_login != PERMIT_YES))
1199                 sshpam_password = badpw;
1200
1201         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1202             (const void *)&passwd_conv);
1203         if (sshpam_err != PAM_SUCCESS)
1204                 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1205                     pam_strerror(sshpam_handle, sshpam_err));
1206
1207         sshpam_err = pam_authenticate(sshpam_handle, flags);
1208         sshpam_password = NULL;
1209         if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1210                 debug("PAM: password authentication accepted for %.100s",
1211                     authctxt->user);
1212                 return 1;
1213         } else {
1214                 debug("PAM: password authentication failed for %.100s: %s",
1215                     authctxt->valid ? authctxt->user : "an illegal user",
1216                     pam_strerror(sshpam_handle, sshpam_err));
1217                 return 0;
1218         }
1219 }
1220 #endif /* USE_PAM */