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 #if !defined(SSHD_PAM_SERVICE)
  70 extern char *__progname;
  71 # define SSHD_PAM_SERVICE               __progname
  72 #endif
  73
  74 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */
  75 #ifdef PAM_SUN_CODEBASE
  76 # define sshpam_const           /* Solaris, HP-UX, SunOS */
  77 #else
  78 # define sshpam_const   const   /* LinuxPAM, OpenPAM, AIX */
  79 #endif
  80
  81 /* Ambiguity in spec: is it an array of pointers or a pointer to an array? */
  82 #ifdef PAM_SUN_CODEBASE
  83 # define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member)
  84 #else
  85 # define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member)
  86 #endif
  87
  88 #include "xmalloc.h"
  89 #include "sshbuf.h"
  90 #include "ssherr.h"
  91 #include "hostfile.h"
  92 #include "auth.h"
  93 #include "auth-pam.h"
  94 #include "canohost.h"
  95 #include "log.h"
  96 #include "msg.h"
  97 #include "packet.h"
  98 #include "misc.h"
  99 #include "servconf.h"
 100 #include "ssh2.h"
 101 #include "auth-options.h"
 102 #ifdef GSSAPI
 103 #include "ssh-gss.h"
 104 #endif
 105 #include "monitor_wrap.h"
 106 #include "blacklist_client.h"
 107
 108 extern ServerOptions options;
 109 extern struct sshbuf *loginmsg;
 110 extern u_int utmp_len;
 111
 112 /* so we don't silently change behaviour */
 113 #ifdef USE_POSIX_THREADS
 114 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
 115 #endif
 116
 117 /*
 118  * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
 119  * and generally a bad idea.  Use at own risk and do not expect support if
 120  * this breaks.
 121  */
 122 #ifdef UNSUPPORTED_POSIX_THREADS_HACK
 123 #include <pthread.h>
 124 /*
 125  * Avoid namespace clash when *not* using pthreads for systems *with*
 126  * pthreads, which unconditionally define pthread_t via sys/types.h
 127  * (e.g. Linux)
 128  */
 129 typedef pthread_t sp_pthread_t;
 130 #else
 131 typedef pid_t sp_pthread_t;
 132 #endif
 133
 134 struct pam_ctxt {
 135         sp_pthread_t     pam_thread;
 136         int              pam_psock;
 137         int              pam_csock;
 138         int              pam_done;
 139 };
 140
 141 static void sshpam_free_ctx(void *);
 142 static struct pam_ctxt *cleanup_ctxt;
 143
 144 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 145 /*
 146  * Simulate threads with processes.
 147  */
 148
 149 static int sshpam_thread_status = -1;
 150 static mysig_t sshpam_oldsig;
 151
 152 static void
 153 sshpam_sigchld_handler(int sig)
 154 {
 155         signal(SIGCHLD, SIG_DFL);
 156         if (cleanup_ctxt == NULL)
 157                 return; /* handler called after PAM cleanup, shouldn't happen */
 158         if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
 159             <= 0) {
 160                 /* PAM thread has not exitted, privsep slave must have */
 161                 kill(cleanup_ctxt->pam_thread, SIGTERM);
 162                 while (waitpid(cleanup_ctxt->pam_thread,
 163                     &sshpam_thread_status, 0) == -1) {
 164                         if (errno == EINTR)
 165                                 continue;
 166                         return;
 167                 }
 168         }
 169         if (WIFSIGNALED(sshpam_thread_status) &&
 170             WTERMSIG(sshpam_thread_status) == SIGTERM)
 171                 return; /* terminated by pthread_cancel */
 172         if (!WIFEXITED(sshpam_thread_status))
 173                 sigdie("PAM: authentication thread exited unexpectedly");
 174         if (WEXITSTATUS(sshpam_thread_status) != 0)
 175                 sigdie("PAM: authentication thread exited uncleanly");
 176 }
 177
 178 /* ARGSUSED */
 179 static void
 180 pthread_exit(void *value)
 181 {
 182         _exit(0);
 183 }
 184
 185 /* ARGSUSED */
 186 static int
 187 pthread_create(sp_pthread_t *thread, const void *attr,
 188     void *(*thread_start)(void *), void *arg)
 189 {
 190         pid_t pid;
 191         struct pam_ctxt *ctx = arg;
 192
 193         sshpam_thread_status = -1;
 194         switch ((pid = fork())) {
 195         case -1:
 196                 error("fork(): %s", strerror(errno));
 197                 return (-1);
 198         case 0:
 199                 close(ctx->pam_psock);
 200                 ctx->pam_psock = -1;
 201                 thread_start(arg);
 202                 _exit(1);
 203         default:
 204                 *thread = pid;
 205                 close(ctx->pam_csock);
 206                 ctx->pam_csock = -1;
 207                 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
 208                 return (0);
 209         }
 210 }
 211
 212 static int
 213 pthread_cancel(sp_pthread_t thread)
 214 {
 215         signal(SIGCHLD, sshpam_oldsig);
 216         return (kill(thread, SIGTERM));
 217 }
 218
 219 /* ARGSUSED */
 220 static int
 221 pthread_join(sp_pthread_t thread, void **value)
 222 {
 223         int status;
 224
 225         if (sshpam_thread_status != -1)
 226                 return (sshpam_thread_status);
 227         signal(SIGCHLD, sshpam_oldsig);
 228         while (waitpid(thread, &status, 0) == -1) {
 229                 if (errno == EINTR)
 230                         continue;
 231                 fatal("%s: waitpid: %s", __func__, strerror(errno));
 232         }
 233         return (status);
 234 }
 235 #endif
 236
 237
 238 static pam_handle_t *sshpam_handle = NULL;
 239 static int sshpam_err = 0;
 240 static int sshpam_authenticated = 0;
 241 static int sshpam_session_open = 0;
 242 static int sshpam_cred_established = 0;
 243 static int sshpam_account_status = -1;
 244 static int sshpam_maxtries_reached = 0;
 245 static char **sshpam_env = NULL;
 246 static Authctxt *sshpam_authctxt = NULL;
 247 static const char *sshpam_password = NULL;
 248
 249 /* Some PAM implementations don't implement this */
 250 #ifndef HAVE_PAM_GETENVLIST
 251 static char **
 252 pam_getenvlist(pam_handle_t *pamh)
 253 {
 254         /*
 255          * XXX - If necessary, we can still support envrionment passing
 256          * for platforms without pam_getenvlist by searching for known
 257          * env vars (e.g. KRB5CCNAME) from the PAM environment.
 258          */
 259          return NULL;
 260 }
 261 #endif
 262
 263 /*
 264  * Some platforms, notably Solaris, do not enforce password complexity
 265  * rules during pam_chauthtok() if the real uid of the calling process
 266  * is 0, on the assumption that it's being called by "passwd" run by root.
 267  * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
 268  * the right thing.
 269  */
 270 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
 271 static int
 272 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
 273 {
 274         int result;
 275
 276         if (sshpam_authctxt == NULL)
 277                 fatal("PAM: sshpam_authctxt not initialized");
 278         if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
 279                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 280         result = pam_chauthtok(pamh, flags);
 281         if (setreuid(0, -1) == -1)
 282                 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
 283         return result;
 284 }
 285 # define pam_chauthtok(a,b)     (sshpam_chauthtok_ruid((a), (b)))
 286 #endif
 287
 288 void
 289 sshpam_password_change_required(int reqd)
 290 {
 291         extern struct sshauthopt *auth_opts;
 292         static int saved_port, saved_agent, saved_x11;
 293
 294         debug3("%s %d", __func__, reqd);
 295         if (sshpam_authctxt == NULL)
 296                 fatal("%s: PAM authctxt not initialized", __func__);
 297         sshpam_authctxt->force_pwchange = reqd;
 298         if (reqd) {
 299                 saved_port = auth_opts->permit_port_forwarding_flag;
 300                 saved_agent = auth_opts->permit_agent_forwarding_flag;
 301                 saved_x11 = auth_opts->permit_x11_forwarding_flag;
 302                 auth_opts->permit_port_forwarding_flag = 0;
 303                 auth_opts->permit_agent_forwarding_flag = 0;
 304                 auth_opts->permit_x11_forwarding_flag = 0;
 305         } else {
 306                 if (saved_port)
 307                         auth_opts->permit_port_forwarding_flag = saved_port;
 308                 if (saved_agent)
 309                         auth_opts->permit_agent_forwarding_flag = saved_agent;
 310                 if (saved_x11)
 311                         auth_opts->permit_x11_forwarding_flag = saved_x11;
 312         }
 313 }
 314
 315 /* Import regular and PAM environment from subprocess */
 316 static void
 317 import_environments(struct sshbuf *b)
 318 {
 319         char *env;
 320         u_int n, i, num_env;
 321         int r;
 322
 323         debug3("PAM: %s entering", __func__);
 324
 325 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 326         /* Import variables set by do_pam_account */
 327         if ((r = sshbuf_get_u32(b, &n)) != 0)
 328                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
 329         if (n > INT_MAX)
 330                 fatal("%s: invalid PAM account status %u", __func__, n);
 331         sshpam_account_status = (int)n;
 332         if ((r = sshbuf_get_u32(b, &n)) != 0)
 333                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
 334         sshpam_password_change_required(n != 0);
 335
 336         /* Import environment from subprocess */
 337         if ((r = sshbuf_get_u32(b, &num_env)) != 0)
 338                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
 339         if (num_env > 1024)
 340                 fatal("%s: received %u environment variables, expected <= 1024",
 341                     __func__, num_env);
 342         sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env));
 343         debug3("PAM: num env strings %d", num_env);
 344         for(i = 0; i < num_env; i++) {
 345                 if ((r = sshbuf_get_cstring(b, &(sshpam_env[i]), NULL)) != 0)
 346                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
 347         }
 348         sshpam_env[num_env] = NULL;
 349
 350         /* Import PAM environment from subprocess */
 351         if ((r = sshbuf_get_u32(b, &num_env)) != 0)
 352                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
 353         debug("PAM: num PAM env strings %d", num_env);
 354         for (i = 0; i < num_env; i++) {
 355                 if ((r = sshbuf_get_cstring(b, &env, NULL)) != 0)
 356                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
 357 #ifdef HAVE_PAM_PUTENV
 358                 /* Errors are not fatal here */
 359                 if ((r = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
 360                         error("PAM: pam_putenv: %s",
 361                             pam_strerror(sshpam_handle, r));
 362                 }
 363 #endif
 364                 /* XXX leak env? */
 365         }
 366 #endif
 367 }
 368
 369 /*
 370  * Conversation function for authentication thread.
 371  */
 372 static int
 373 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
 374     struct pam_response **resp, void *data)
 375 {
 376         struct sshbuf *buffer;
 377         struct pam_ctxt *ctxt;
 378         struct pam_response *reply;
 379         int r, i;
 380         u_char status;
 381
 382         debug3("PAM: %s entering, %d messages", __func__, n);
 383         *resp = NULL;
 384
 385         if (data == NULL) {
 386                 error("PAM: conversation function passed a null context");
 387                 return (PAM_CONV_ERR);
 388         }
 389         ctxt = data;
 390         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 391                 return (PAM_CONV_ERR);
 392
 393         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 394                 return PAM_CONV_ERR;
 395         if ((buffer = sshbuf_new()) == NULL) {
 396                 free(reply);
 397                 return PAM_CONV_ERR;
 398         }
 399
 400         for (i = 0; i < n; ++i) {
 401                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 402                 case PAM_PROMPT_ECHO_OFF:
 403                 case PAM_PROMPT_ECHO_ON:
 404                         if ((r = sshbuf_put_cstring(buffer,
 405                             PAM_MSG_MEMBER(msg, i, msg))) != 0)
 406                                 fatal("%s: buffer error: %s",
 407                                     __func__, ssh_err(r));
 408                         if (ssh_msg_send(ctxt->pam_csock,
 409                             PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1)
 410                                 goto fail;
 411
 412                         if (ssh_msg_recv(ctxt->pam_csock, buffer) == -1)
 413                                 goto fail;
 414                         if ((r = sshbuf_get_u8(buffer, &status)) != 0)
 415                                 fatal("%s: buffer error: %s",
 416                                     __func__, ssh_err(r));
 417                         if (status != PAM_AUTHTOK)
 418                                 goto fail;
 419                         if ((r = sshbuf_get_cstring(buffer,
 420                             &reply[i].resp, NULL)) != 0)
 421                                 fatal("%s: buffer error: %s",
 422                                     __func__, ssh_err(r));
 423                         break;
 424                 case PAM_ERROR_MSG:
 425                 case PAM_TEXT_INFO:
 426                         if ((r = sshbuf_put_cstring(buffer,
 427                             PAM_MSG_MEMBER(msg, i, msg))) != 0)
 428                                 fatal("%s: buffer error: %s",
 429                                     __func__, ssh_err(r));
 430                         if (ssh_msg_send(ctxt->pam_csock,
 431                             PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1)
 432                                 goto fail;
 433                         break;
 434                 default:
 435                         goto fail;
 436                 }
 437                 sshbuf_reset(buffer);
 438         }
 439         sshbuf_free(buffer);
 440         *resp = reply;
 441         return (PAM_SUCCESS);
 442
 443  fail:
 444         for(i = 0; i < n; i++) {
 445                 free(reply[i].resp);
 446         }
 447         free(reply);
 448         sshbuf_free(buffer);
 449         return (PAM_CONV_ERR);
 450 }
 451
 452 /*
 453  * Authentication thread.
 454  */
 455 static void *
 456 sshpam_thread(void *ctxtp)
 457 {
 458         struct pam_ctxt *ctxt = ctxtp;
 459         struct sshbuf *buffer = NULL;
 460         struct pam_conv sshpam_conv;
 461         int r, flags = (options.permit_empty_passwd == 0 ?
 462             PAM_DISALLOW_NULL_AUTHTOK : 0);
 463 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 464         extern char **environ;
 465         char **env_from_pam;
 466         u_int i;
 467         const char *pam_user;
 468         const char **ptr_pam_user = &pam_user;
 469         char *tz = getenv("TZ");
 470
 471         sshpam_err = pam_get_item(sshpam_handle, PAM_USER,
 472             (sshpam_const void **)ptr_pam_user);
 473         if (sshpam_err != PAM_SUCCESS)
 474                 goto auth_fail;
 475
 476         environ[0] = NULL;
 477         if (tz != NULL)
 478                 if (setenv("TZ", tz, 1) == -1)
 479                         error("PAM: could not set TZ environment: %s",
 480                             strerror(errno));
 481
 482         if (sshpam_authctxt != NULL) {
 483                 setproctitle("%s [pam]",
 484                     sshpam_authctxt->valid ? pam_user : "unknown");
 485         }
 486 #endif
 487
 488         sshpam_conv.conv = sshpam_thread_conv;
 489         sshpam_conv.appdata_ptr = ctxt;
 490
 491         if (sshpam_authctxt == NULL)
 492                 fatal("%s: PAM authctxt not initialized", __func__);
 493
 494         if ((buffer = sshbuf_new()) == NULL)
 495                 fatal("%s: sshbuf_new failed", __func__);
 496
 497         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
 498             (const void *)&sshpam_conv);
 499         if (sshpam_err != PAM_SUCCESS)
 500                 goto auth_fail;
 501         sshpam_err = pam_authenticate(sshpam_handle, flags);
 502         if (sshpam_err == PAM_MAXTRIES)
 503                 sshpam_set_maxtries_reached(1);
 504         if (sshpam_err != PAM_SUCCESS)
 505                 goto auth_fail;
 506
 507         if (!do_pam_account()) {
 508                 sshpam_err = PAM_ACCT_EXPIRED;
 509                 goto auth_fail;
 510         }
 511         if (sshpam_authctxt->force_pwchange) {
 512                 sshpam_err = pam_chauthtok(sshpam_handle,
 513                     PAM_CHANGE_EXPIRED_AUTHTOK);
 514                 if (sshpam_err != PAM_SUCCESS)
 515                         goto auth_fail;
 516                 sshpam_password_change_required(0);
 517         }
 518
 519         if ((r = sshbuf_put_cstring(buffer, "OK")) != 0)
 520                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
 521
 522 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
 523         /* Export variables set by do_pam_account */
 524         if ((r = sshbuf_put_u32(buffer, sshpam_account_status)) != 0 ||
 525             (r = sshbuf_put_u32(buffer, sshpam_authctxt->force_pwchange)) != 0)
 526                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
 527
 528         /* Export any environment strings set in child */
 529         for (i = 0; environ[i] != NULL; i++) {
 530                 /* Count */
 531                 if (i > INT_MAX)
 532                         fatal("%s: too many enviornment strings", __func__);
 533         }
 534         if ((r = sshbuf_put_u32(buffer, i)) != 0)
 535                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
 536         for (i = 0; environ[i] != NULL; i++) {
 537                 if ((r = sshbuf_put_cstring(buffer, environ[i])) != 0)
 538                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
 539         }
 540         /* Export any environment strings set by PAM in child */
 541         env_from_pam = pam_getenvlist(sshpam_handle);
 542         for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) {
 543                 /* Count */
 544                 if (i > INT_MAX)
 545                         fatal("%s: too many PAM enviornment strings", __func__);
 546         }
 547         if ((r = sshbuf_put_u32(buffer, i)) != 0)
 548                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
 549         for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) {
 550                 if ((r = sshbuf_put_cstring(buffer, env_from_pam[i])) != 0)
 551                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
 552         }
 553 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */
 554
 555         /* XXX - can't do much about an error here */
 556         ssh_msg_send(ctxt->pam_csock, sshpam_err, buffer);
 557         sshbuf_free(buffer);
 558         pthread_exit(NULL);
 559
 560  auth_fail:
 561         if ((r = sshbuf_put_cstring(buffer,
 562             pam_strerror(sshpam_handle, sshpam_err))) != 0)
 563                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
 564         /* XXX - can't do much about an error here */
 565         if (sshpam_err == PAM_ACCT_EXPIRED)
 566                 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, buffer);
 567         else if (sshpam_maxtries_reached)
 568                 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, buffer);
 569         else
 570                 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, buffer);
 571         sshbuf_free(buffer);
 572         pthread_exit(NULL);
 573
 574         return (NULL); /* Avoid warning for non-pthread case */
 575 }
 576
 577 void
 578 sshpam_thread_cleanup(void)
 579 {
 580         struct pam_ctxt *ctxt = cleanup_ctxt;
 581
 582         debug3("PAM: %s entering", __func__);
 583         if (ctxt != NULL && ctxt->pam_thread != 0) {
 584                 pthread_cancel(ctxt->pam_thread);
 585                 pthread_join(ctxt->pam_thread, NULL);
 586                 close(ctxt->pam_psock);
 587                 close(ctxt->pam_csock);
 588                 memset(ctxt, 0, sizeof(*ctxt));
 589                 cleanup_ctxt = NULL;
 590         }
 591 }
 592
 593 static int
 594 sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
 595     struct pam_response **resp, void *data)
 596 {
 597         debug3("PAM: %s entering, %d messages", __func__, n);
 598         return (PAM_CONV_ERR);
 599 }
 600
 601 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
 602
 603 static int
 604 sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
 605     struct pam_response **resp, void *data)
 606 {
 607         struct pam_response *reply;
 608         int r, i;
 609
 610         debug3("PAM: %s called with %d messages", __func__, n);
 611         *resp = NULL;
 612
 613         if (n <= 0 || n > PAM_MAX_NUM_MSG)
 614                 return (PAM_CONV_ERR);
 615
 616         if ((reply = calloc(n, sizeof(*reply))) == NULL)
 617                 return (PAM_CONV_ERR);
 618
 619         for (i = 0; i < n; ++i) {
 620                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
 621                 case PAM_ERROR_MSG:
 622                 case PAM_TEXT_INFO:
 623                         if ((r = sshbuf_putf(loginmsg, "%s\n",
 624                             PAM_MSG_MEMBER(msg, i, msg))) != 0)
 625                                 fatal("%s: buffer error: %s",
 626                                     __func__, ssh_err(r));
 627                         reply[i].resp_retcode = PAM_SUCCESS;
 628                         break;
 629                 default:
 630                         goto fail;
 631                 }
 632         }
 633         *resp = reply;
 634         return (PAM_SUCCESS);
 635
 636  fail:
 637         for(i = 0; i < n; i++) {
 638                 free(reply[i].resp);
 639         }
 640         free(reply);
 641         return (PAM_CONV_ERR);
 642 }
 643
 644 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
 645
 646 void
 647 sshpam_cleanup(void)
 648 {
 649         if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor()))
 650                 return;
 651         debug("PAM: cleanup");
 652         pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
 653         if (sshpam_session_open) {
 654                 debug("PAM: closing session");
 655                 pam_close_session(sshpam_handle, PAM_SILENT);
 656                 sshpam_session_open = 0;
 657         }
 658         if (sshpam_cred_established) {
 659                 debug("PAM: deleting credentials");
 660                 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
 661                 sshpam_cred_established = 0;
 662         }
 663         sshpam_authenticated = 0;
 664         pam_end(sshpam_handle, sshpam_err);
 665         sshpam_handle = NULL;
 666 }
 667
 668 static int
 669 sshpam_init(Authctxt *authctxt)
 670 {
 671         const char *pam_rhost, *pam_user, *user = authctxt->user;
 672         const char **ptr_pam_user = &pam_user;
 673         struct ssh *ssh = active_state; /* XXX */
 674
 675         if (sshpam_handle != NULL) {
 676                 /* We already have a PAM context; check if the user matches */
 677                 sshpam_err = pam_get_item(sshpam_handle,
 678                     PAM_USER, (sshpam_const void **)ptr_pam_user);
 679                 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
 680                         return (0);
 681                 pam_end(sshpam_handle, sshpam_err);
 682                 sshpam_handle = NULL;
 683         }
 684         debug("PAM: initializing for \"%s\"", user);
 685         sshpam_err =
 686             pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
 687         sshpam_authctxt = authctxt;
 688
 689         if (sshpam_err != PAM_SUCCESS) {
 690                 pam_end(sshpam_handle, sshpam_err);
 691                 sshpam_handle = NULL;
 692                 return (-1);
 693         }
 694         pam_rhost = auth_get_canonical_hostname(ssh, options.use_dns);
 695         debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
 696         sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
 697         if (sshpam_err != PAM_SUCCESS) {
 698                 pam_end(sshpam_handle, sshpam_err);
 699                 sshpam_handle = NULL;
 700                 return (-1);
 701         }
 702 #ifdef PAM_TTY_KLUDGE
 703         /*
 704          * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
 705          * sshd doesn't set the tty until too late in the auth process and
 706          * may not even set one (for tty-less connections)
 707          */
 708         debug("PAM: setting PAM_TTY to \"ssh\"");
 709         sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
 710         if (sshpam_err != PAM_SUCCESS) {
 711                 pam_end(sshpam_handle, sshpam_err);
 712                 sshpam_handle = NULL;
 713                 return (-1);
 714         }
 715 #endif
 716         return (0);
 717 }
 718
 719 static void
 720 expose_authinfo(const char *caller)
 721 {
 722         char *auth_info;
 723
 724         /*
 725          * Expose authentication information to PAM.
 726          * The environment variable is versioned. Please increment the
 727          * version suffix if the format of session_info changes.
 728          */
 729         if (sshpam_authctxt->session_info == NULL)
 730                 auth_info = xstrdup("");
 731         else if ((auth_info = sshbuf_dup_string(
 732             sshpam_authctxt->session_info)) == NULL)
 733                 fatal("%s: sshbuf_dup_string failed", __func__);
 734
 735         debug2("%s: auth information in SSH_AUTH_INFO_0", caller);
 736         do_pam_putenv("SSH_AUTH_INFO_0", auth_info);
 737         free(auth_info);
 738 }
 739
 740 static void *
 741 sshpam_init_ctx(Authctxt *authctxt)
 742 {
 743         struct pam_ctxt *ctxt;
 744         int socks[2];
 745
 746         debug3("PAM: %s entering", __func__);
 747         /*
 748          * Refuse to start if we don't have PAM enabled or do_pam_account
 749          * has previously failed.
 750          */
 751         if (!options.use_pam || sshpam_account_status == 0)
 752                 return NULL;
 753
 754         /* Initialize PAM */
 755         if (sshpam_init(authctxt) == -1) {
 756                 error("PAM: initialization failed");
 757                 return (NULL);
 758         }
 759
 760         expose_authinfo(__func__);
 761         ctxt = xcalloc(1, sizeof *ctxt);
 762
 763         /* Start the authentication thread */
 764         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
 765                 error("PAM: failed create sockets: %s", strerror(errno));
 766                 free(ctxt);
 767                 return (NULL);
 768         }
 769         ctxt->pam_psock = socks[0];
 770         ctxt->pam_csock = socks[1];
 771         if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
 772                 error("PAM: failed to start authentication thread: %s",
 773                     strerror(errno));
 774                 close(socks[0]);
 775                 close(socks[1]);
 776                 free(ctxt);
 777                 return (NULL);
 778         }
 779         cleanup_ctxt = ctxt;
 780         return (ctxt);
 781 }
 782
 783 static int
 784 sshpam_query(void *ctx, char **name, char **info,
 785     u_int *num, char ***prompts, u_int **echo_on)
 786 {
 787         struct ssh *ssh = active_state; /* XXX */
 788         struct sshbuf *buffer;
 789         struct pam_ctxt *ctxt = ctx;
 790         size_t plen;
 791         u_char type;
 792         char *msg;
 793         size_t len, mlen;
 794         int r;
 795
 796         debug3("PAM: %s entering", __func__);
 797         if ((buffer = sshbuf_new()) == NULL)
 798                 fatal("%s: sshbuf_new failed", __func__);
 799         *name = xstrdup("");
 800         *info = xstrdup("");
 801         *prompts = xmalloc(sizeof(char *));
 802         **prompts = NULL;
 803         plen = 0;
 804         *echo_on = xmalloc(sizeof(u_int));
 805         while (ssh_msg_recv(ctxt->pam_psock, buffer) == 0) {
 806                 if ((r = sshbuf_get_u8(buffer, &type)) != 0 ||
 807                     (r = sshbuf_get_cstring(buffer, &msg, &mlen)) != 0)
 808                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
 809                 switch (type) {
 810                 case PAM_PROMPT_ECHO_ON:
 811                 case PAM_PROMPT_ECHO_OFF:
 812                         *num = 1;
 813                         len = plen + mlen + 1;
 814                         **prompts = xreallocarray(**prompts, 1, len);
 815                         strlcpy(**prompts + plen, msg, len - plen);
 816                         plen += mlen;
 817                         **echo_on = (type == PAM_PROMPT_ECHO_ON);
 818                         free(msg);
 819                         return (0);
 820                 case PAM_ERROR_MSG:
 821                 case PAM_TEXT_INFO:
 822                         /* accumulate messages */
 823                         len = plen + mlen + 2;
 824                         **prompts = xreallocarray(**prompts, 1, len);
 825                         strlcpy(**prompts + plen, msg, len - plen);
 826                         plen += mlen;
 827                         strlcat(**prompts + plen, "\n", len - plen);
 828                         plen++;
 829                         free(msg);
 830                         break;
 831                 case PAM_ACCT_EXPIRED:
 832                 case PAM_MAXTRIES:
 833                         if (type == PAM_ACCT_EXPIRED)
 834                                 sshpam_account_status = 0;
 835                         if (type == PAM_MAXTRIES)
 836                                 sshpam_set_maxtries_reached(1);
 837                         /* FALLTHROUGH */
 838                 case PAM_AUTH_ERR:
 839                         debug3("PAM: %s", pam_strerror(sshpam_handle, type));
 840                         if (**prompts != NULL && strlen(**prompts) != 0) {
 841                                 *info = **prompts;
 842                                 **prompts = NULL;
 843                                 *num = 0;
 844                                 **echo_on = 0;
 845                                 ctxt->pam_done = -1;
 846                                 free(msg);
 847                                 return 0;
 848                         }
 849                         /* FALLTHROUGH */
 850                 case PAM_SUCCESS:
 851                         if (**prompts != NULL) {
 852                                 /* drain any accumulated messages */
 853                                 debug("PAM: %s", **prompts);
 854                                 if ((r = sshbuf_put(loginmsg, **prompts,
 855                                     strlen(**prompts))) != 0)
 856                                         fatal("%s: buffer error: %s",
 857                                             __func__, ssh_err(r));
 858                                 free(**prompts);
 859                                 **prompts = NULL;
 860                         }
 861                         if (type == PAM_SUCCESS) {
 862                                 if (!sshpam_authctxt->valid ||
 863                                     (sshpam_authctxt->pw->pw_uid == 0 &&
 864                                     options.permit_root_login != PERMIT_YES))
 865                                         fatal("Internal error: PAM auth "
 866                                             "succeeded when it should have "
 867                                             "failed");
 868                                 import_environments(buffer);
 869                                 *num = 0;
 870                                 **echo_on = 0;
 871                                 ctxt->pam_done = 1;
 872                                 free(msg);
 873                                 return (0);
 874                         }
 875                         BLACKLIST_NOTIFY(BLACKLIST_BAD_USER,
 876                             sshpam_authctxt->user);
 877                         error("PAM: %s for %s%.100s from %.100s", msg,
 878                             sshpam_authctxt->valid ? "" : "illegal user ",
 879                             sshpam_authctxt->user,
 880                             auth_get_canonical_hostname(ssh, options.use_dns));
 881                         /* FALLTHROUGH */
 882                 default:
 883                         *num = 0;
 884                         **echo_on = 0;
 885                         free(msg);
 886                         ctxt->pam_done = -1;
 887                         return (-1);
 888                 }
 889         }
 890         return (-1);
 891 }
 892
 893 /*
 894  * Returns a junk password of identical length to that the user supplied.
 895  * Used to mitigate timing attacks against crypt(3)/PAM stacks that
 896  * vary processing time in proportion to password length.
 897  */
 898 static char *
 899 fake_password(const char *wire_password)
 900 {
 901         const char junk[] = "\b\n\r\177INCORRECT";
 902         char *ret = NULL;
 903         size_t i, l = wire_password != NULL ? strlen(wire_password) : 0;
 904
 905         if (l >= INT_MAX)
 906                 fatal("%s: password length too long: %zu", __func__, l);
 907
 908         ret = malloc(l + 1);
 909         if (ret == NULL)
 910                 return NULL;
 911         for (i = 0; i < l; i++)
 912                 ret[i] = junk[i % (sizeof(junk) - 1)];
 913         ret[i] = '\0';
 914         return ret;
 915 }
 916
 917 /* XXX - see also comment in auth-chall.c:verify_response */
 918 static int
 919 sshpam_respond(void *ctx, u_int num, char **resp)
 920 {
 921         struct sshbuf *buffer;
 922         struct pam_ctxt *ctxt = ctx;
 923         char *fake;
 924         int r;
 925
 926         debug2("PAM: %s entering, %u responses", __func__, num);
 927         switch (ctxt->pam_done) {
 928         case 1:
 929                 sshpam_authenticated = 1;
 930                 return (0);
 931         case 0:
 932                 break;
 933         default:
 934                 return (-1);
 935         }
 936         if (num != 1) {
 937                 error("PAM: expected one response, got %u", num);
 938                 return (-1);
 939         }
 940         if ((buffer = sshbuf_new()) == NULL)
 941                 fatal("%s: sshbuf_new failed", __func__);
 942         if (sshpam_authctxt->valid &&
 943             (sshpam_authctxt->pw->pw_uid != 0 ||
 944             options.permit_root_login == PERMIT_YES)) {
 945                 if ((r = sshbuf_put_cstring(buffer, *resp)) != 0)
 946                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
 947         } else {
 948                 fake = fake_password(*resp);
 949                 if ((r = sshbuf_put_cstring(buffer, fake)) != 0)
 950                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
 951                 free(fake);
 952         }
 953         if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, buffer) == -1) {
 954                 sshbuf_free(buffer);
 955                 return (-1);
 956         }
 957         sshbuf_free(buffer);
 958         return (1);
 959 }
 960
 961 static void
 962 sshpam_free_ctx(void *ctxtp)
 963 {
 964         struct pam_ctxt *ctxt = ctxtp;
 965
 966         debug3("PAM: %s entering", __func__);
 967         sshpam_thread_cleanup();
 968         free(ctxt);
 969         /*
 970          * We don't call sshpam_cleanup() here because we may need the PAM
 971          * handle at a later stage, e.g. when setting up a session.  It's
 972          * still on the cleanup list, so pam_end() *will* be called before
 973          * the server process terminates.
 974          */
 975 }
 976
 977 KbdintDevice sshpam_device = {
 978         "pam",
 979         sshpam_init_ctx,
 980         sshpam_query,
 981         sshpam_respond,
 982         sshpam_free_ctx
 983 };
 984
 985 KbdintDevice mm_sshpam_device = {
 986         "pam",
 987         mm_sshpam_init_ctx,
 988         mm_sshpam_query,
 989         mm_sshpam_respond,
 990         mm_sshpam_free_ctx
 991 };
 992
 993 /*
 994  * This replaces auth-pam.c
 995  */
 996 void
 997 start_pam(Authctxt *authctxt)
 998 {
 999         if (!options.use_pam)
1000                 fatal("PAM: initialisation requested when UsePAM=no");
1001
1002         if (sshpam_init(authctxt) == -1)
1003                 fatal("PAM: initialisation failed");
1004 }
1005
1006 void
1007 finish_pam(void)
1008 {
1009         sshpam_cleanup();
1010 }
1011
1012
1013 u_int
1014 do_pam_account(void)
1015 {
1016         debug("%s: called", __func__);
1017         if (sshpam_account_status != -1)
1018                 return (sshpam_account_status);
1019
1020         expose_authinfo(__func__);
1021
1022         sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
1023         debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
1024             pam_strerror(sshpam_handle, sshpam_err));
1025
1026         if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
1027                 sshpam_account_status = 0;
1028                 return (sshpam_account_status);
1029         }
1030
1031         if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
1032                 sshpam_password_change_required(1);
1033
1034         sshpam_account_status = 1;
1035         return (sshpam_account_status);
1036 }
1037
1038 void
1039 do_pam_setcred(int init)
1040 {
1041         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1042             (const void *)&store_conv);
1043         if (sshpam_err != PAM_SUCCESS)
1044                 fatal("PAM: failed to set PAM_CONV: %s",
1045                     pam_strerror(sshpam_handle, sshpam_err));
1046         if (init) {
1047                 debug("PAM: establishing credentials");
1048                 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
1049         } else {
1050                 debug("PAM: reinitializing credentials");
1051                 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
1052         }
1053         if (sshpam_err == PAM_SUCCESS) {
1054                 sshpam_cred_established = 1;
1055                 return;
1056         }
1057         if (sshpam_authenticated)
1058                 fatal("PAM: pam_setcred(): %s",
1059                     pam_strerror(sshpam_handle, sshpam_err));
1060         else
1061                 debug("PAM: pam_setcred(): %s",
1062                     pam_strerror(sshpam_handle, sshpam_err));
1063 }
1064
1065 static int
1066 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
1067     struct pam_response **resp, void *data)
1068 {
1069         char input[PAM_MAX_MSG_SIZE];
1070         struct pam_response *reply;
1071         int i;
1072
1073         debug3("PAM: %s called with %d messages", __func__, n);
1074
1075         *resp = NULL;
1076
1077         if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
1078                 return (PAM_CONV_ERR);
1079
1080         if ((reply = calloc(n, sizeof(*reply))) == NULL)
1081                 return (PAM_CONV_ERR);
1082
1083         for (i = 0; i < n; ++i) {
1084                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1085                 case PAM_PROMPT_ECHO_OFF:
1086                         reply[i].resp =
1087                             read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
1088                             RP_ALLOW_STDIN);
1089                         reply[i].resp_retcode = PAM_SUCCESS;
1090                         break;
1091                 case PAM_PROMPT_ECHO_ON:
1092                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1093                         if (fgets(input, sizeof input, stdin) == NULL)
1094                                 input[0] = '\0';
1095                         if ((reply[i].resp = strdup(input)) == NULL)
1096                                 goto fail;
1097                         reply[i].resp_retcode = PAM_SUCCESS;
1098                         break;
1099                 case PAM_ERROR_MSG:
1100                 case PAM_TEXT_INFO:
1101                         fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1102                         reply[i].resp_retcode = PAM_SUCCESS;
1103                         break;
1104                 default:
1105                         goto fail;
1106                 }
1107         }
1108         *resp = reply;
1109         return (PAM_SUCCESS);
1110
1111  fail:
1112         for(i = 0; i < n; i++) {
1113                 free(reply[i].resp);
1114         }
1115         free(reply);
1116         return (PAM_CONV_ERR);
1117 }
1118
1119 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
1120
1121 /*
1122  * XXX this should be done in the authentication phase, but ssh1 doesn't
1123  * support that
1124  */
1125 void
1126 do_pam_chauthtok(void)
1127 {
1128         if (use_privsep)
1129                 fatal("Password expired (unable to change with privsep)");
1130         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1131             (const void *)&tty_conv);
1132         if (sshpam_err != PAM_SUCCESS)
1133                 fatal("PAM: failed to set PAM_CONV: %s",
1134                     pam_strerror(sshpam_handle, sshpam_err));
1135         debug("PAM: changing password");
1136         sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
1137         if (sshpam_err != PAM_SUCCESS)
1138                 fatal("PAM: pam_chauthtok(): %s",
1139                     pam_strerror(sshpam_handle, sshpam_err));
1140 }
1141
1142 void
1143 do_pam_session(struct ssh *ssh)
1144 {
1145         debug3("PAM: opening session");
1146
1147         expose_authinfo(__func__);
1148
1149         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1150             (const void *)&store_conv);
1151         if (sshpam_err != PAM_SUCCESS)
1152                 fatal("PAM: failed to set PAM_CONV: %s",
1153                     pam_strerror(sshpam_handle, sshpam_err));
1154         sshpam_err = pam_open_session(sshpam_handle, 0);
1155         if (sshpam_err == PAM_SUCCESS)
1156                 sshpam_session_open = 1;
1157         else {
1158                 sshpam_session_open = 0;
1159                 auth_restrict_session(ssh);
1160                 error("PAM: pam_open_session(): %s",
1161                     pam_strerror(sshpam_handle, sshpam_err));
1162         }
1163
1164 }
1165
1166 int
1167 is_pam_session_open(void)
1168 {
1169         return sshpam_session_open;
1170 }
1171
1172 /*
1173  * Set a PAM environment string. We need to do this so that the session
1174  * modules can handle things like Kerberos/GSI credentials that appear
1175  * during the ssh authentication process.
1176  */
1177 int
1178 do_pam_putenv(char *name, char *value)
1179 {
1180         int ret = 1;
1181 #ifdef HAVE_PAM_PUTENV
1182         char *compound;
1183         size_t len;
1184
1185         len = strlen(name) + strlen(value) + 2;
1186         compound = xmalloc(len);
1187
1188         snprintf(compound, len, "%s=%s", name, value);
1189         ret = pam_putenv(sshpam_handle, compound);
1190         free(compound);
1191 #endif
1192
1193         return (ret);
1194 }
1195
1196 char **
1197 fetch_pam_child_environment(void)
1198 {
1199         return sshpam_env;
1200 }
1201
1202 char **
1203 fetch_pam_environment(void)
1204 {
1205         return (pam_getenvlist(sshpam_handle));
1206 }
1207
1208 void
1209 free_pam_environment(char **env)
1210 {
1211         char **envp;
1212
1213         if (env == NULL)
1214                 return;
1215
1216         for (envp = env; *envp; envp++)
1217                 free(*envp);
1218         free(env);
1219 }
1220
1221 /*
1222  * "Blind" conversation function for password authentication.  Assumes that
1223  * echo-off prompts are for the password and stores messages for later
1224  * display.
1225  */
1226 static int
1227 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1228     struct pam_response **resp, void *data)
1229 {
1230         struct pam_response *reply;
1231         int r, i;
1232         size_t len;
1233
1234         debug3("PAM: %s called with %d messages", __func__, n);
1235
1236         *resp = NULL;
1237
1238         if (n <= 0 || n > PAM_MAX_NUM_MSG)
1239                 return (PAM_CONV_ERR);
1240
1241         if ((reply = calloc(n, sizeof(*reply))) == NULL)
1242                 return (PAM_CONV_ERR);
1243
1244         for (i = 0; i < n; ++i) {
1245                 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1246                 case PAM_PROMPT_ECHO_OFF:
1247                         if (sshpam_password == NULL)
1248                                 goto fail;
1249                         if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1250                                 goto fail;
1251                         reply[i].resp_retcode = PAM_SUCCESS;
1252                         break;
1253                 case PAM_ERROR_MSG:
1254                 case PAM_TEXT_INFO:
1255                         len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1256                         if (len > 0) {
1257                                 if ((r = sshbuf_putf(loginmsg, "%s\n",
1258                                     PAM_MSG_MEMBER(msg, i, msg))) != 0)
1259                                         fatal("%s: buffer error: %s",
1260                                             __func__, ssh_err(r));
1261                         }
1262                         if ((reply[i].resp = strdup("")) == NULL)
1263                                 goto fail;
1264                         reply[i].resp_retcode = PAM_SUCCESS;
1265                         break;
1266                 default:
1267                         goto fail;
1268                 }
1269         }
1270         *resp = reply;
1271         return (PAM_SUCCESS);
1272
1273  fail:
1274         for(i = 0; i < n; i++) {
1275                 free(reply[i].resp);
1276         }
1277         free(reply);
1278         return (PAM_CONV_ERR);
1279 }
1280
1281 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1282
1283 /*
1284  * Attempt password authentication via PAM
1285  */
1286 int
1287 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1288 {
1289         int flags = (options.permit_empty_passwd == 0 ?
1290             PAM_DISALLOW_NULL_AUTHTOK : 0);
1291         char *fake = NULL;
1292
1293         if (!options.use_pam || sshpam_handle == NULL)
1294                 fatal("PAM: %s called when PAM disabled or failed to "
1295                     "initialise.", __func__);
1296
1297         sshpam_password = password;
1298         sshpam_authctxt = authctxt;
1299
1300         /*
1301          * If the user logging in is invalid, or is root but is not permitted
1302          * by PermitRootLogin, use an invalid password to prevent leaking
1303          * information via timing (eg if the PAM config has a delay on fail).
1304          */
1305         if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1306             options.permit_root_login != PERMIT_YES))
1307                 sshpam_password = fake = fake_password(password);
1308
1309         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1310             (const void *)&passwd_conv);
1311         if (sshpam_err != PAM_SUCCESS)
1312                 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1313                     pam_strerror(sshpam_handle, sshpam_err));
1314
1315         sshpam_err = pam_authenticate(sshpam_handle, flags);
1316         sshpam_password = NULL;
1317         free(fake);
1318         if (sshpam_err == PAM_MAXTRIES)
1319                 sshpam_set_maxtries_reached(1);
1320         if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1321                 debug("PAM: password authentication accepted for %.100s",
1322                     authctxt->user);
1323                 return 1;
1324         } else {
1325                 debug("PAM: password authentication failed for %.100s: %s",
1326                     authctxt->valid ? authctxt->user : "an illegal user",
1327                     pam_strerror(sshpam_handle, sshpam_err));
1328                 return 0;
1329         }
1330 }
1331
1332 int
1333 sshpam_get_maxtries_reached(void)
1334 {
1335         return sshpam_maxtries_reached;
1336 }
1337
1338 void
1339 sshpam_set_maxtries_reached(int reached)
1340 {
1341         if (reached == 0 || sshpam_maxtries_reached)
1342                 return;
1343         sshpam_maxtries_reached = 1;
1344         options.password_authentication = 0;
1345         options.kbd_interactive_authentication = 0;
1346         options.challenge_response_authentication = 0;
1347 }
1348 #endif /* USE_PAM */