granicus.if.org Git - linux-pam/blob - modules/pam_unix/pam_unix_passwd.c

   1 /*
   2  * Main coding by Elliot Lee <sopwith@redhat.com>, Red Hat Software.
   3  * Copyright (C) 1996.
   4  * Copyright (c) Jan Rêkorajski, 1999.
   5  * Copyright (c) Red Hat, Inc., 2007, 2008.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, and the entire permission notice in its entirety,
  12  *    including the disclaimer of warranties.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. The name of the author may not be used to endorse or promote
  17  *    products derived from this software without specific prior
  18  *    written permission.
  19  *
  20  * ALTERNATIVELY, this product may be distributed under the terms of
  21  * the GNU Public License, in which case the provisions of the GPL are
  22  * required INSTEAD OF the above restrictions.  (This clause is
  23  * necessary due to a potential bad interaction between the GPL and
  24  * the restrictions contained in a BSD-style copyright.)
  25  *
  26  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
  27  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  28  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  29  * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
  30  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  31  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  32  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  34  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  36  * OF THE POSSIBILITY OF SUCH DAMAGE.
  37  */
  38
  39 #include "config.h"
  40
  41 #include <stdio.h>
  42 #include <stdlib.h>
  43 #include <stdarg.h>
  44 #include <string.h>
  45 #include <malloc.h>
  46 #include <unistd.h>
  47 #include <errno.h>
  48 #include <sys/types.h>
  49 #include <pwd.h>
  50 #include <syslog.h>
  51 #include <shadow.h>
  52 #include <time.h>               /* for time() */
  53 #include <fcntl.h>
  54 #include <ctype.h>
  55 #include <sys/time.h>
  56 #include <sys/stat.h>
  57
  58 #include <signal.h>
  59 #include <errno.h>
  60 #include <sys/wait.h>
  61
  62 #include <security/_pam_macros.h>
  63
  64 /* indicate the following groups are defined */
  65
  66 #ifdef PAM_STATIC
  67 # include "pam_unix_static.h"
  68 #else
  69 # define PAM_SM_PASSWORD
  70 #endif
  71
  72 #include <security/pam_modules.h>
  73 #include <security/pam_ext.h>
  74 #include <security/pam_modutil.h>
  75
  76 #include "md5.h"
  77 #include "support.h"
  78 #include "passverify.h"
  79 #include "bigcrypt.h"
  80
  81 #if (HAVE_YP_GET_DEFAULT_DOMAIN || HAVE_GETDOMAINNAME) && HAVE_YP_MASTER
  82 # define HAVE_NIS
  83 #endif
  84
  85 #ifdef HAVE_NIS
  86 # include <rpc/rpc.h>
  87
  88 # if HAVE_RPCSVC_YP_PROT_H
  89 #  include <rpcsvc/yp_prot.h>
  90 # endif
  91
  92 # if HAVE_RPCSVC_YPCLNT_H
  93 #  include <rpcsvc/ypclnt.h>
  94 # endif
  95
  96 # include "yppasswd.h"
  97
  98 # if !HAVE_DECL_GETRPCPORT
  99 extern int getrpcport(const char *host, unsigned long prognum,
 100                       unsigned long versnum, unsigned int proto);
 101 # endif                         /* GNU libc 2.1 */
 102 #endif
 103
 104 /*
 105    How it works:
 106    Gets in username (has to be done) from the calling program
 107    Does authentication of user (only if we are not running as root)
 108    Gets new password/checks for sanity
 109    Sets it.
 110  */
 111
 112 /* data tokens */
 113
 114 #define _UNIX_OLD_AUTHTOK       "-UN*X-OLD-PASS"
 115 #define _UNIX_NEW_AUTHTOK       "-UN*X-NEW-PASS"
 116
 117 #define MAX_PASSWD_TRIES        3
 118
 119 #ifdef HAVE_NIS
 120 static char *getNISserver(pam_handle_t *pamh, unsigned int ctrl)
 121 {
 122         char *master;
 123         char *domainname;
 124         int port, err;
 125
 126 #ifdef HAVE_YP_GET_DEFAULT_DOMAIN
 127         if ((err = yp_get_default_domain(&domainname)) != 0) {
 128                 pam_syslog(pamh, LOG_WARNING, "can't get local yp domain: %s",
 129                          yperr_string(err));
 130                 return NULL;
 131         }
 132 #elif defined(HAVE_GETDOMAINNAME)
 133         char domainname_res[256];
 134
 135         if (getdomainname (domainname_res, sizeof (domainname_res)) == 0)
 136           {
 137             if (strcmp (domainname_res, "(none)") == 0)
 138               {
 139                 /* If domainname is not set, some systems will return "(none)" */
 140                 domainname_res[0] = '\0';
 141               }
 142             domainname = domainname_res;
 143           }
 144         else domainname = NULL;
 145 #endif
 146
 147         if ((err = yp_master(domainname, "passwd.byname", &master)) != 0) {
 148                 pam_syslog(pamh, LOG_WARNING, "can't find the master ypserver: %s",
 149                          yperr_string(err));
 150                 return NULL;
 151         }
 152         port = getrpcport(master, YPPASSWDPROG, YPPASSWDPROC_UPDATE, IPPROTO_UDP);
 153         if (port == 0) {
 154                 pam_syslog(pamh, LOG_WARNING,
 155                          "yppasswdd not running on NIS master host");
 156                 return NULL;
 157         }
 158         if (port >= IPPORT_RESERVED) {
 159                 pam_syslog(pamh, LOG_WARNING,
 160                          "yppasswd daemon running on illegal port");
 161                 return NULL;
 162         }
 163         if (on(UNIX_DEBUG, ctrl)) {
 164           pam_syslog(pamh, LOG_DEBUG, "Use NIS server on %s with port %d",
 165                      master, port);
 166         }
 167         return master;
 168 }
 169 #endif
 170
 171 #ifdef WITH_SELINUX
 172
 173 static int _unix_run_update_binary(pam_handle_t *pamh, unsigned int ctrl, const char *user,
 174     const char *fromwhat, const char *towhat, int remember)
 175 {
 176     int retval, child, fds[2];
 177     struct sigaction newsa, oldsa;
 178
 179     D(("called."));
 180     /* create a pipe for the password */
 181     if (pipe(fds) != 0) {
 182         D(("could not make pipe"));
 183         return PAM_AUTH_ERR;
 184     }
 185
 186     if (off(UNIX_NOREAP, ctrl)) {
 187         /*
 188          * This code arranges that the demise of the child does not cause
 189          * the application to receive a signal it is not expecting - which
 190          * may kill the application or worse.
 191          *
 192          * The "noreap" module argument is provided so that the admin can
 193          * override this behavior.
 194          */
 195         memset(&newsa, '\0', sizeof(newsa));
 196         newsa.sa_handler = SIG_DFL;
 197         sigaction(SIGCHLD, &newsa, &oldsa);
 198     }
 199
 200     /* fork */
 201     child = fork();
 202     if (child == 0) {
 203         int i=0;
 204         struct rlimit rlim;
 205         static char *envp[] = { NULL };
 206         char *args[] = { NULL, NULL, NULL, NULL, NULL, NULL };
 207         char buffer[16];
 208
 209         /* XXX - should really tidy up PAM here too */
 210
 211         /* reopen stdin as pipe */
 212         dup2(fds[0], STDIN_FILENO);
 213
 214         if (getrlimit(RLIMIT_NOFILE,&rlim)==0) {
 215           if (rlim.rlim_max >= MAX_FD_NO)
 216             rlim.rlim_max = MAX_FD_NO;
 217           for (i=0; i < (int)rlim.rlim_max; i++) {
 218             if (i != STDIN_FILENO)
 219                 close(i);
 220           }
 221         }
 222
 223         /* exec binary helper */
 224         args[0] = x_strdup(UPDATE_HELPER);
 225         args[1] = x_strdup(user);
 226         args[2] = x_strdup("update");
 227         if (on(UNIX_SHADOW, ctrl))
 228                 args[3] = x_strdup("1");
 229         else
 230                 args[3] = x_strdup("0");
 231
 232         snprintf(buffer, sizeof(buffer), "%d", remember);
 233         args[4] = x_strdup(buffer);
 234
 235         execve(UPDATE_HELPER, args, envp);
 236
 237         /* should not get here: exit with error */
 238         D(("helper binary is not available"));
 239         _exit(PAM_AUTHINFO_UNAVAIL);
 240     } else if (child > 0) {
 241         /* wait for child */
 242         /* if the stored password is NULL */
 243         int rc=0;
 244         if (fromwhat)
 245           pam_modutil_write(fds[1], fromwhat, strlen(fromwhat)+1);
 246         else
 247           pam_modutil_write(fds[1], "", 1);
 248         if (towhat) {
 249           pam_modutil_write(fds[1], towhat, strlen(towhat)+1);
 250         }
 251         else
 252           pam_modutil_write(fds[1], "", 1);
 253
 254         close(fds[0]);       /* close here to avoid possible SIGPIPE above */
 255         close(fds[1]);
 256         rc=waitpid(child, &retval, 0);  /* wait for helper to complete */
 257         if (rc<0) {
 258           pam_syslog(pamh, LOG_ERR, "unix_update waitpid failed: %m");
 259           retval = PAM_AUTHTOK_ERR;
 260         } else if (!WIFEXITED(retval)) {
 261           pam_syslog(pamh, LOG_ERR, "unix_update abnormal exit: %d", retval);
 262           retval = PAM_AUTHTOK_ERR;
 263         } else {
 264           retval = WEXITSTATUS(retval);
 265         }
 266     } else {
 267         D(("fork failed"));
 268         close(fds[0]);
 269         close(fds[1]);
 270         retval = PAM_AUTH_ERR;
 271     }
 272
 273     if (off(UNIX_NOREAP, ctrl)) {
 274         sigaction(SIGCHLD, &oldsa, NULL);   /* restore old signal handler */
 275     }
 276
 277     return retval;
 278 }
 279 #endif
 280
 281 static int check_old_password(const char *forwho, const char *newpass)
 282 {
 283         static char buf[16384];
 284         char *s_luser, *s_uid, *s_npas, *s_pas;
 285         int retval = PAM_SUCCESS;
 286         FILE *opwfile;
 287         size_t len = strlen(forwho);
 288
 289         opwfile = fopen(OLD_PASSWORDS_FILE, "r");
 290         if (opwfile == NULL)
 291                 return PAM_ABORT;
 292
 293         while (fgets(buf, 16380, opwfile)) {
 294                 if (!strncmp(buf, forwho, len) && (buf[len] == ':' ||
 295                         buf[len] == ',')) {
 296                         char *sptr;
 297                         buf[strlen(buf) - 1] = '\0';
 298                         s_luser = strtok_r(buf, ":,", &sptr);
 299                         s_uid = strtok_r(NULL, ":,", &sptr);
 300                         s_npas = strtok_r(NULL, ":,", &sptr);
 301                         s_pas = strtok_r(NULL, ":,", &sptr);
 302                         while (s_pas != NULL) {
 303                                 char *md5pass = Goodcrypt_md5(newpass, s_pas);
 304                                 if (!strcmp(md5pass, s_pas)) {
 305                                         _pam_delete(md5pass);
 306                                         retval = PAM_AUTHTOK_ERR;
 307                                         break;
 308                                 }
 309                                 s_pas = strtok_r(NULL, ":,", &sptr);
 310                                 _pam_delete(md5pass);
 311                         }
 312                         break;
 313                 }
 314         }
 315         fclose(opwfile);
 316
 317         return retval;
 318 }
 319
 320 static int _do_setpass(pam_handle_t* pamh, const char *forwho,
 321                        const char *fromwhat,
 322                        char *towhat, unsigned int ctrl, int remember)
 323 {
 324         struct passwd *pwd = NULL;
 325         int retval = 0;
 326         int unlocked = 0;
 327         char *master = NULL;
 328
 329         D(("called"));
 330
 331         pwd = getpwnam(forwho);
 332
 333         if (pwd == NULL) {
 334                 retval = PAM_AUTHTOK_ERR;
 335                 goto done;
 336         }
 337
 338         if (on(UNIX_NIS, ctrl) && _unix_comesfromsource(pamh, forwho, 0, 1)) {
 339 #ifdef HAVE_NIS
 340           if ((master=getNISserver(pamh, ctrl)) != NULL) {
 341                 struct timeval timeout;
 342                 struct yppasswd yppwd;
 343                 CLIENT *clnt;
 344                 int status;
 345                 enum clnt_stat err;
 346
 347                 /* Unlock passwd file to avoid deadlock */
 348                 unlock_pwdf();
 349                 unlocked = 1;
 350
 351                 /* Initialize password information */
 352                 yppwd.newpw.pw_passwd = pwd->pw_passwd;
 353                 yppwd.newpw.pw_name = pwd->pw_name;
 354                 yppwd.newpw.pw_uid = pwd->pw_uid;
 355                 yppwd.newpw.pw_gid = pwd->pw_gid;
 356                 yppwd.newpw.pw_gecos = pwd->pw_gecos;
 357                 yppwd.newpw.pw_dir = pwd->pw_dir;
 358                 yppwd.newpw.pw_shell = pwd->pw_shell;
 359                 yppwd.oldpass = fromwhat ? strdup (fromwhat) : strdup ("");
 360                 yppwd.newpw.pw_passwd = towhat;
 361
 362                 D(("Set password %s for %s", yppwd.newpw.pw_passwd, forwho));
 363
 364                 /* The yppasswd.x file said `unix authentication required',
 365                  * so I added it. This is the only reason it is in here.
 366                  * My yppasswdd doesn't use it, but maybe some others out there
 367                  * do.                                        --okir
 368                  */
 369                 clnt = clnt_create(master, YPPASSWDPROG, YPPASSWDVERS, "udp");
 370                 clnt->cl_auth = authunix_create_default();
 371                 memset((char *) &status, '\0', sizeof(status));
 372                 timeout.tv_sec = 25;
 373                 timeout.tv_usec = 0;
 374                 err = clnt_call(clnt, YPPASSWDPROC_UPDATE,
 375                                 (xdrproc_t) xdr_yppasswd, (char *) &yppwd,
 376                                 (xdrproc_t) xdr_int, (char *) &status,
 377                                 timeout);
 378
 379                 free (yppwd.oldpass);
 380
 381                 if (err) {
 382                         _make_remark(pamh, ctrl, PAM_TEXT_INFO,
 383                                 clnt_sperrno(err));
 384                 } else if (status) {
 385                         D(("Error while changing NIS password.\n"));
 386                 }
 387                 D(("The password has%s been changed on %s.",
 388                    (err || status) ? " not" : "", master));
 389                 pam_syslog(pamh, LOG_NOTICE, "password%s changed for %s on %s",
 390                          (err || status) ? " not" : "", pwd->pw_name, master);
 391
 392                 auth_destroy(clnt->cl_auth);
 393                 clnt_destroy(clnt);
 394                 if (err || status) {
 395                         _make_remark(pamh, ctrl, PAM_TEXT_INFO,
 396                                 _("NIS password could not be changed."));
 397                         retval = PAM_TRY_AGAIN;
 398                 }
 399 #ifdef PAM_DEBUG
 400                 sleep(5);
 401 #endif
 402             } else {
 403                     retval = PAM_TRY_AGAIN;
 404             }
 405 #else
 406           if (on(UNIX_DEBUG, ctrl)) {
 407             pam_syslog(pamh, LOG_DEBUG, "No NIS support available");
 408           }
 409
 410           retval = PAM_TRY_AGAIN;
 411 #endif
 412         }
 413
 414         if (_unix_comesfromsource(pamh, forwho, 1, 0)) {
 415                 if(unlocked) {
 416                         if (lock_pwdf() != PAM_SUCCESS) {
 417                                 return PAM_AUTHTOK_LOCK_BUSY;
 418                         }
 419                 }
 420 #ifdef WITH_SELINUX
 421                 if (unix_selinux_confined())
 422                           return _unix_run_update_binary(pamh, ctrl, forwho, fromwhat, towhat, remember);
 423 #endif
 424                 /* first, save old password */
 425                 if (save_old_password(pamh, forwho, fromwhat, remember)) {
 426                         retval = PAM_AUTHTOK_ERR;
 427                         goto done;
 428                 }
 429                 if (on(UNIX_SHADOW, ctrl) || is_pwd_shadowed(pwd)) {
 430                         retval = unix_update_shadow(pamh, forwho, towhat);
 431                         if (retval == PAM_SUCCESS)
 432                                 if (!is_pwd_shadowed(pwd))
 433                                         retval = unix_update_passwd(pamh, forwho, "x");
 434                 } else {
 435                         retval = unix_update_passwd(pamh, forwho, towhat);
 436                 }
 437         }
 438
 439
 440 done:
 441         unlock_pwdf();
 442
 443         return retval;
 444 }
 445
 446 static int _unix_verify_shadow(pam_handle_t *pamh, const char *user, unsigned int ctrl)
 447 {
 448         struct passwd *pwent = NULL;    /* Password and shadow password */
 449         struct spwd *spent = NULL;      /* file entries for the user */
 450         int daysleft;
 451         int retval;
 452
 453         retval = get_account_info(pamh, user, &pwent, &spent);
 454         if (retval == PAM_USER_UNKNOWN) {
 455                 return retval;
 456         }
 457
 458         if (retval == PAM_SUCCESS && spent == NULL)
 459                 return PAM_SUCCESS;
 460
 461         if (retval == PAM_UNIX_RUN_HELPER) {
 462                 retval = _unix_run_verify_binary(pamh, ctrl, user, &daysleft);
 463                 if (retval == PAM_AUTH_ERR || retval == PAM_USER_UNKNOWN)
 464                         return retval;
 465         }
 466         else if (retval == PAM_SUCCESS)
 467                 retval = check_shadow_expiry(pamh, spent, &daysleft);
 468
 469         if (on(UNIX__IAMROOT, ctrl) || retval == PAM_NEW_AUTHTOK_REQD)
 470                 return PAM_SUCCESS;
 471
 472         return retval;
 473 }
 474
 475 static int _pam_unix_approve_pass(pam_handle_t * pamh
 476                                   ,unsigned int ctrl
 477                                   ,const char *pass_old
 478                                   ,const char *pass_new,
 479                                   int pass_min_len)
 480 {
 481         const void *user;
 482         const char *remark = NULL;
 483         int retval = PAM_SUCCESS;
 484
 485         D(("&new=%p, &old=%p", pass_old, pass_new));
 486         D(("new=[%s]", pass_new));
 487         D(("old=[%s]", pass_old));
 488
 489         if (pass_new == NULL || (pass_old && !strcmp(pass_old, pass_new))) {
 490                 if (on(UNIX_DEBUG, ctrl)) {
 491                         pam_syslog(pamh, LOG_DEBUG, "bad authentication token");
 492                 }
 493                 _make_remark(pamh, ctrl, PAM_ERROR_MSG, pass_new == NULL ?
 494                         _("No password supplied") : _("Password unchanged"));
 495                 return PAM_AUTHTOK_ERR;
 496         }
 497         /*
 498          * if one wanted to hardwire authentication token strength
 499          * checking this would be the place - AGM
 500          */
 501
 502         retval = pam_get_item(pamh, PAM_USER, &user);
 503         if (retval != PAM_SUCCESS) {
 504                 if (on(UNIX_DEBUG, ctrl)) {
 505                         pam_syslog(pamh, LOG_ERR, "Can not get username");
 506                         return PAM_AUTHTOK_ERR;
 507                 }
 508         }
 509         if (off(UNIX__IAMROOT, ctrl)) {
 510                 if (strlen(pass_new) < pass_min_len)
 511                   remark = _("You must choose a longer password");
 512                 D(("length check [%s]", remark));
 513                 if (on(UNIX_REMEMBER_PASSWD, ctrl)) {
 514                         if ((retval = check_old_password(user, pass_new)) == PAM_AUTHTOK_ERR)
 515                           remark = _("Password has been already used. Choose another.");
 516                         if (retval == PAM_ABORT) {
 517                                 pam_syslog(pamh, LOG_ERR, "can't open %s file to check old passwords",
 518                                         OLD_PASSWORDS_FILE);
 519                                 return retval;
 520                         }
 521                 }
 522         }
 523         if (remark) {
 524                 _make_remark(pamh, ctrl, PAM_ERROR_MSG, remark);
 525                 retval = PAM_AUTHTOK_ERR;
 526         }
 527         return retval;
 528 }
 529
 530 int
 531 pam_sm_chauthtok(pam_handle_t *pamh, int flags, int argc, const char **argv)
 532 {
 533         unsigned int ctrl, lctrl;
 534         int retval;
 535         int remember = -1;
 536         int rounds = -1;
 537         int pass_min_len = 0;
 538
 539         /* <DO NOT free() THESE> */
 540         const char *user;
 541         const void *pass_old, *pass_new;
 542         /* </DO NOT free() THESE> */
 543
 544         D(("called."));
 545
 546         ctrl = _set_ctrl(pamh, flags, &remember, &rounds, &pass_min_len,
 547                          argc, argv);
 548
 549         /*
 550          * First get the name of a user
 551          */
 552         retval = pam_get_user(pamh, &user, NULL);
 553         if (retval == PAM_SUCCESS) {
 554                 /*
 555                  * Various libraries at various times have had bugs related to
 556                  * '+' or '-' as the first character of a user name. Don't
 557                  * allow them.
 558                  */
 559                 if (user == NULL || user[0] == '-' || user[0] == '+') {
 560                         pam_syslog(pamh, LOG_ERR, "bad username [%s]", user);
 561                         return PAM_USER_UNKNOWN;
 562                 }
 563                 if (retval == PAM_SUCCESS && on(UNIX_DEBUG, ctrl))
 564                         pam_syslog(pamh, LOG_DEBUG, "username [%s] obtained",
 565                                  user);
 566         } else {
 567                 if (on(UNIX_DEBUG, ctrl))
 568                         pam_syslog(pamh, LOG_DEBUG,
 569                                  "password - could not identify user");
 570                 return retval;
 571         }
 572
 573         D(("Got username of %s", user));
 574
 575         /*
 576          * Before we do anything else, check to make sure that the user's
 577          * info is in one of the databases we can modify from this module,
 578          * which currently is 'files' and 'nis'.  We have to do this because
 579          * getpwnam() doesn't tell you *where* the information it gives you
 580          * came from, nor should it.  That's our job.
 581          */
 582         if (_unix_comesfromsource(pamh, user, 1, on(UNIX_NIS, ctrl)) == 0) {
 583                 pam_syslog(pamh, LOG_DEBUG,
 584                          "user \"%s\" does not exist in /etc/passwd%s",
 585                          user, on(UNIX_NIS, ctrl) ? " or NIS" : "");
 586                 return PAM_USER_UNKNOWN;
 587         } else {
 588                 struct passwd *pwd;
 589                 _unix_getpwnam(pamh, user, 1, 1, &pwd);
 590                 if (pwd == NULL) {
 591                         pam_syslog(pamh, LOG_DEBUG,
 592                                 "user \"%s\" has corrupted passwd entry",
 593                                 user);
 594                         return PAM_USER_UNKNOWN;
 595                 }
 596         }
 597
 598         /*
 599          * This is not an AUTH module!
 600          */
 601         if (on(UNIX__NONULL, ctrl))
 602                 set(UNIX__NULLOK, ctrl);
 603
 604         if (on(UNIX__PRELIM, ctrl)) {
 605                 /*
 606                  * obtain and verify the current password (OLDAUTHTOK) for
 607                  * the user.
 608                  */
 609                 char *Announce;
 610
 611                 D(("prelim check"));
 612
 613                 if (_unix_blankpasswd(pamh, ctrl, user)) {
 614                         return PAM_SUCCESS;
 615                 } else if (off(UNIX__IAMROOT, ctrl)) {
 616                         /* instruct user what is happening */
 617                         if (asprintf(&Announce, _("Changing password for %s."),
 618                                 user) < 0) {
 619                                 pam_syslog(pamh, LOG_CRIT,
 620                                          "password - out of memory");
 621                                 return PAM_BUF_ERR;
 622                         }
 623
 624                         lctrl = ctrl;
 625                         set(UNIX__OLD_PASSWD, lctrl);
 626                         retval = _unix_read_password(pamh, lctrl
 627                                                      ,Announce
 628                                              ,_("(current) UNIX password: ")
 629                                                      ,NULL
 630                                                      ,_UNIX_OLD_AUTHTOK
 631                                              ,&pass_old);
 632                         free(Announce);
 633
 634                         if (retval != PAM_SUCCESS) {
 635                                 pam_syslog(pamh, LOG_NOTICE,
 636                                     "password - (old) token not obtained");
 637                                 return retval;
 638                         }
 639                         /* verify that this is the password for this user */
 640
 641                         retval = _unix_verify_password(pamh, user, pass_old, ctrl);
 642                 } else {
 643                         D(("process run by root so do nothing this time around"));
 644                         pass_old = NULL;
 645                         retval = PAM_SUCCESS;   /* root doesn't have too */
 646                 }
 647
 648                 if (retval != PAM_SUCCESS) {
 649                         D(("Authentication failed"));
 650                         pass_old = NULL;
 651                         return retval;
 652                 }
 653                 retval = pam_set_item(pamh, PAM_OLDAUTHTOK, (const void *) pass_old);
 654                 pass_old = NULL;
 655                 if (retval != PAM_SUCCESS) {
 656                         pam_syslog(pamh, LOG_CRIT,
 657                                  "failed to set PAM_OLDAUTHTOK");
 658                 }
 659                 retval = _unix_verify_shadow(pamh,user, ctrl);
 660                 if (retval == PAM_AUTHTOK_ERR) {
 661                         if (off(UNIX__IAMROOT, ctrl))
 662                                 _make_remark(pamh, ctrl, PAM_ERROR_MSG,
 663                                              _("You must wait longer to change your password"));
 664                         else
 665                                 retval = PAM_SUCCESS;
 666                 }
 667         } else if (on(UNIX__UPDATE, ctrl)) {
 668                 /*
 669                  * tpass is used below to store the _pam_md() return; it
 670                  * should be _pam_delete()'d.
 671                  */
 672
 673                 char *tpass = NULL;
 674                 int retry = 0;
 675
 676                 /*
 677                  * obtain the proposed password
 678                  */
 679
 680                 D(("do update"));
 681
 682                 /*
 683                  * get the old token back. NULL was ok only if root [at this
 684                  * point we assume that this has already been enforced on a
 685                  * previous call to this function].
 686                  */
 687
 688                 if (off(UNIX_NOT_SET_PASS, ctrl)) {
 689                         retval = pam_get_item(pamh, PAM_OLDAUTHTOK
 690                                               ,&pass_old);
 691                 } else {
 692                         retval = pam_get_data(pamh, _UNIX_OLD_AUTHTOK
 693                                               ,&pass_old);
 694                         if (retval == PAM_NO_MODULE_DATA) {
 695                                 retval = PAM_SUCCESS;
 696                                 pass_old = NULL;
 697                         }
 698                 }
 699                 D(("pass_old [%s]", pass_old));
 700
 701                 if (retval != PAM_SUCCESS) {
 702                         pam_syslog(pamh, LOG_NOTICE, "user not authenticated");
 703                         return retval;
 704                 }
 705
 706                 D(("get new password now"));
 707
 708                 lctrl = ctrl;
 709
 710                 if (on(UNIX_USE_AUTHTOK, lctrl)) {
 711                         set(UNIX_USE_FIRST_PASS, lctrl);
 712                 }
 713                 retry = 0;
 714                 retval = PAM_AUTHTOK_ERR;
 715                 while ((retval != PAM_SUCCESS) && (retry++ < MAX_PASSWD_TRIES)) {
 716                         /*
 717                          * use_authtok is to force the use of a previously entered
 718                          * password -- needed for pluggable password strength checking
 719                          */
 720
 721                         retval = _unix_read_password(pamh, lctrl
 722                                                      ,NULL
 723                                              ,_("Enter new UNIX password: ")
 724                                             ,_("Retype new UNIX password: ")
 725                                                      ,_UNIX_NEW_AUTHTOK
 726                                              ,&pass_new);
 727
 728                         if (retval != PAM_SUCCESS) {
 729                                 if (on(UNIX_DEBUG, ctrl)) {
 730                                         pam_syslog(pamh, LOG_ALERT,
 731                                                  "password - new password not obtained");
 732                                 }
 733                                 pass_old = NULL;        /* tidy up */
 734                                 return retval;
 735                         }
 736                         D(("returned to _unix_chauthtok"));
 737
 738                         /*
 739                          * At this point we know who the user is and what they
 740                          * propose as their new password. Verify that the new
 741                          * password is acceptable.
 742                          */
 743
 744                         if (*(const char *)pass_new == '\0') {  /* "\0" password = NULL */
 745                                 pass_new = NULL;
 746                         }
 747                         retval = _pam_unix_approve_pass(pamh, ctrl, pass_old,
 748                                                         pass_new, pass_min_len);
 749
 750                         if (retval != PAM_SUCCESS && off(UNIX_NOT_SET_PASS, ctrl)) {
 751                                 pam_set_item(pamh, PAM_AUTHTOK, NULL);
 752                         }
 753                 }
 754
 755                 if (retval != PAM_SUCCESS) {
 756                         pam_syslog(pamh, LOG_NOTICE,
 757                                  "new password not acceptable");
 758                         pass_new = pass_old = NULL;     /* tidy up */
 759                         return retval;
 760                 }
 761                 if (lock_pwdf() != PAM_SUCCESS) {
 762                         return PAM_AUTHTOK_LOCK_BUSY;
 763                 }
 764
 765                 if (pass_old) {
 766                         retval = _unix_verify_password(pamh, user, pass_old, ctrl);
 767                         if (retval != PAM_SUCCESS) {
 768                                 pam_syslog(pamh, LOG_NOTICE, "user password changed by another process");
 769                                 unlock_pwdf();
 770                                 return retval;
 771                         }
 772                 }
 773
 774                 retval = _unix_verify_shadow(pamh, user, ctrl);
 775                 if (retval != PAM_SUCCESS) {
 776                         pam_syslog(pamh, LOG_NOTICE, "user shadow entry expired");
 777                         unlock_pwdf();
 778                         return retval;
 779                 }
 780
 781                 retval = _pam_unix_approve_pass(pamh, ctrl, pass_old, pass_new,
 782                                                 pass_min_len);
 783                 if (retval != PAM_SUCCESS) {
 784                         pam_syslog(pamh, LOG_NOTICE,
 785                                  "new password not acceptable 2");
 786                         pass_new = pass_old = NULL;     /* tidy up */
 787                         unlock_pwdf();
 788                         return retval;
 789                 }
 790
 791                 /*
 792                  * By reaching here we have approved the passwords and must now
 793                  * rebuild the password database file.
 794                  */
 795
 796                 /*
 797                  * First we encrypt the new password.
 798                  */
 799
 800                 tpass = create_password_hash(pamh, pass_new, ctrl, rounds);
 801                 if (tpass == NULL) {
 802                         pam_syslog(pamh, LOG_CRIT,
 803                                 "crypt() failure or out of memory for password");
 804                         pass_new = pass_old = NULL;     /* tidy up */
 805                         unlock_pwdf();
 806                         return PAM_BUF_ERR;
 807                 }
 808
 809                 D(("password processed"));
 810
 811                 /* update the password database(s) -- race conditions..? */
 812
 813                 retval = _do_setpass(pamh, user, pass_old, tpass, ctrl,
 814                                      remember);
 815                 /* _do_setpass has called unlock_pwdf for us */
 816
 817                 _pam_delete(tpass);
 818                 pass_old = pass_new = NULL;
 819         } else {                /* something has broken with the module */
 820                 pam_syslog(pamh, LOG_ALERT,
 821                          "password received unknown request");
 822                 retval = PAM_ABORT;
 823         }
 824
 825         D(("retval was %d", retval));
 826
 827         return retval;
 828 }