lib/libpam/modules/pam_unix/pam_unix.c

   1 /*-
   2  * Copyright 1998 Juniper Networks, Inc.
   3  * All rights reserved.
   4  * Copyright (c) 2002-2003 Networks Associates Technology, Inc.
   5  * All rights reserved.
   6  *
   7  * Portions of this software was developed for the FreeBSD Project by
   8  * ThinkSec AS and NAI Labs, the Security Research Division of Network
   9  * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
  10  * ("CBOSS"), as part of the DARPA CHATS research program.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. The name of the author may not be used to endorse or promote
  21  *    products derived from this software without specific prior written
  22  *    permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #include <sys/cdefs.h>
  38 __FBSDID("$FreeBSD$");
  39
  40 #include <sys/param.h>
  41 #include <sys/socket.h>
  42 #include <sys/time.h>
  43 #include <netinet/in.h>
  44 #include <arpa/inet.h>
  45
  46 #include <login_cap.h>
  47 #include <netdb.h>
  48 #include <pwd.h>
  49 #include <stdlib.h>
  50 #include <string.h>
  51 #include <stdio.h>
  52 #include <syslog.h>
  53 #include <time.h>
  54 #include <unistd.h>
  55
  56 #include <libutil.h>
  57
  58 #ifdef YP
  59 #include <ypclnt.h>
  60 #endif
  61
  62 #define PAM_SM_AUTH
  63 #define PAM_SM_ACCOUNT
  64 #define PAM_SM_PASSWORD
  65
  66 #include <security/pam_appl.h>
  67 #include <security/pam_modules.h>
  68 #include <security/pam_mod_misc.h>
  69
  70 #define PASSWORD_HASH           "md5"
  71 #define DEFAULT_WARN            (2L * 7L * 86400L)  /* Two weeks */
  72 #define SALTSIZE                32
  73
  74 #define LOCKED_PREFIX           "*LOCKED*"
  75 #define LOCKED_PREFIX_LEN       (sizeof(LOCKED_PREFIX) - 1)
  76
  77 static void makesalt(char []);
  78
  79 static char password_hash[] =           PASSWORD_HASH;
  80
  81 #define PAM_OPT_LOCAL_PASS      "local_pass"
  82 #define PAM_OPT_NIS_PASS        "nis_pass"
  83
  84 /*
  85  * authentication management
  86  */
  87 PAM_EXTERN int
  88 pam_sm_authenticate(pam_handle_t *pamh, int flags __unused,
  89     int argc __unused, const char *argv[] __unused)
  90 {
  91         login_cap_t *lc;
  92         struct passwd *pwd;
  93         int retval;
  94         const char *pass, *user, *realpw, *prompt;
  95
  96         if (openpam_get_option(pamh, PAM_OPT_AUTH_AS_SELF)) {
  97                 user = getlogin();
  98         } else {
  99                 retval = pam_get_user(pamh, &user, NULL);
 100                 if (retval != PAM_SUCCESS)
 101                         return (retval);
 102         }
 103         pwd = getpwnam(user);
 104
 105         PAM_LOG("Got user: %s", user);
 106
 107         if (pwd != NULL) {
 108                 PAM_LOG("Doing real authentication");
 109                 realpw = pwd->pw_passwd;
 110                 if (realpw[0] == '\0') {
 111                         if (!(flags & PAM_DISALLOW_NULL_AUTHTOK) &&
 112                             openpam_get_option(pamh, PAM_OPT_NULLOK))
 113                                 return (PAM_SUCCESS);
 114                         PAM_LOG("Password is empty, using fake password");
 115                         realpw = "*";
 116                 }
 117                 lc = login_getpwclass(pwd);
 118         } else {
 119                 PAM_LOG("Doing dummy authentication");
 120                 realpw = "*";
 121                 lc = login_getclass(NULL);
 122         }
 123         prompt = login_getcapstr(lc, "passwd_prompt", NULL, NULL);
 124         retval = pam_get_authtok(pamh, PAM_AUTHTOK, &pass, prompt);
 125         login_close(lc);
 126         if (retval != PAM_SUCCESS)
 127                 return (retval);
 128         PAM_LOG("Got password");
 129         if (strnlen(pass, _PASSWORD_LEN + 1) > _PASSWORD_LEN) {
 130                 PAM_LOG("Password is too long, using fake password");
 131                 realpw = "*";
 132         }
 133         if (strcmp(crypt(pass, realpw), realpw) == 0)
 134                 return (PAM_SUCCESS);
 135
 136         PAM_VERBOSE_ERROR("UNIX authentication refused");
 137         return (PAM_AUTH_ERR);
 138 }
 139
 140 PAM_EXTERN int
 141 pam_sm_setcred(pam_handle_t *pamh __unused, int flags __unused,
 142     int argc __unused, const char *argv[] __unused)
 143 {
 144
 145         return (PAM_SUCCESS);
 146 }
 147
 148 /*
 149  * account management
 150  */
 151 PAM_EXTERN int
 152 pam_sm_acct_mgmt(pam_handle_t *pamh, int flags __unused,
 153     int argc __unused, const char *argv[] __unused)
 154 {
 155         struct addrinfo hints, *res;
 156         struct passwd *pwd;
 157         struct timeval tp;
 158         login_cap_t *lc;
 159         time_t warntime;
 160         int retval;
 161         const char *user;
 162         const void *rhost, *tty;
 163         char rhostip[MAXHOSTNAMELEN] = "";
 164
 165         retval = pam_get_user(pamh, &user, NULL);
 166         if (retval != PAM_SUCCESS)
 167                 return (retval);
 168
 169         if (user == NULL || (pwd = getpwnam(user)) == NULL)
 170                 return (PAM_SERVICE_ERR);
 171
 172         PAM_LOG("Got user: %s", user);
 173
 174         retval = pam_get_item(pamh, PAM_RHOST, &rhost);
 175         if (retval != PAM_SUCCESS)
 176                 return (retval);
 177
 178         retval = pam_get_item(pamh, PAM_TTY, &tty);
 179         if (retval != PAM_SUCCESS)
 180                 return (retval);
 181
 182         if (*pwd->pw_passwd == '\0' &&
 183             (flags & PAM_DISALLOW_NULL_AUTHTOK) != 0)
 184                 return (PAM_NEW_AUTHTOK_REQD);
 185
 186         if (strncmp(pwd->pw_passwd, LOCKED_PREFIX, LOCKED_PREFIX_LEN) == 0)
 187                 return (PAM_AUTH_ERR);
 188
 189         lc = login_getpwclass(pwd);
 190         if (lc == NULL) {
 191                 PAM_LOG("Unable to get login class for user %s", user);
 192                 return (PAM_SERVICE_ERR);
 193         }
 194
 195         PAM_LOG("Got login_cap");
 196
 197         if (pwd->pw_change || pwd->pw_expire)
 198                 gettimeofday(&tp, NULL);
 199
 200         /*
 201          * Check pw_expire before pw_change - no point in letting the
 202          * user change the password on an expired account.
 203          */
 204
 205         if (pwd->pw_expire) {
 206                 warntime = login_getcaptime(lc, "warnexpire",
 207                     DEFAULT_WARN, DEFAULT_WARN);
 208                 if (tp.tv_sec >= pwd->pw_expire) {
 209                         login_close(lc);
 210                         return (PAM_ACCT_EXPIRED);
 211                 } else if (pwd->pw_expire - tp.tv_sec < warntime &&
 212                     (flags & PAM_SILENT) == 0) {
 213                         pam_error(pamh, "Warning: your account expires on %s",
 214                             ctime(&pwd->pw_expire));
 215                 }
 216         }
 217
 218         retval = PAM_SUCCESS;
 219         if (pwd->pw_change) {
 220                 warntime = login_getcaptime(lc, "warnpassword",
 221                     DEFAULT_WARN, DEFAULT_WARN);
 222                 if (tp.tv_sec >= pwd->pw_change) {
 223                         retval = PAM_NEW_AUTHTOK_REQD;
 224                 } else if (pwd->pw_change - tp.tv_sec < warntime &&
 225                     (flags & PAM_SILENT) == 0) {
 226                         pam_error(pamh, "Warning: your password expires on %s",
 227                             ctime(&pwd->pw_change));
 228                 }
 229         }
 230
 231         /*
 232          * From here on, we must leave retval untouched (unless we
 233          * know we're going to fail), because we need to remember
 234          * whether we're supposed to return PAM_SUCCESS or
 235          * PAM_NEW_AUTHTOK_REQD.
 236          */
 237
 238         if (rhost && *(const char *)rhost != '\0') {
 239                 memset(&hints, 0, sizeof(hints));
 240                 hints.ai_family = AF_UNSPEC;
 241                 if (getaddrinfo(rhost, NULL, &hints, &res) == 0) {
 242                         getnameinfo(res->ai_addr, res->ai_addrlen,
 243                             rhostip, sizeof(rhostip), NULL, 0,
 244                             NI_NUMERICHOST);
 245                 }
 246                 if (res != NULL)
 247                         freeaddrinfo(res);
 248         }
 249
 250         /*
 251          * Check host / tty / time-of-day restrictions
 252          */
 253
 254         if (!auth_hostok(lc, rhost, rhostip) ||
 255             !auth_ttyok(lc, tty) ||
 256             !auth_timeok(lc, time(NULL)))
 257                 retval = PAM_AUTH_ERR;
 258
 259         login_close(lc);
 260
 261         return (retval);
 262 }
 263
 264 /*
 265  * password management
 266  *
 267  * standard Unix and NIS password changing
 268  */
 269 PAM_EXTERN int
 270 pam_sm_chauthtok(pam_handle_t *pamh, int flags,
 271     int argc __unused, const char *argv[] __unused)
 272 {
 273 #ifdef YP
 274         struct ypclnt *ypclnt;
 275         const void *yp_domain, *yp_server;
 276 #endif
 277         char salt[SALTSIZE + 1];
 278         login_cap_t *lc;
 279         struct passwd *pwd, *old_pwd;
 280         const char *user, *old_pass, *new_pass;
 281         char *encrypted;
 282         time_t passwordtime;
 283         int pfd, tfd, retval;
 284
 285         if (openpam_get_option(pamh, PAM_OPT_AUTH_AS_SELF))
 286                 user = getlogin();
 287         else {
 288                 retval = pam_get_user(pamh, &user, NULL);
 289                 if (retval != PAM_SUCCESS)
 290                         return (retval);
 291         }
 292         pwd = getpwnam(user);
 293
 294         if (pwd == NULL)
 295                 return (PAM_AUTHTOK_RECOVERY_ERR);
 296
 297         PAM_LOG("Got user: %s", user);
 298
 299         if (flags & PAM_PRELIM_CHECK) {
 300
 301                 PAM_LOG("PRELIM round");
 302
 303                 if (getuid() == 0 &&
 304                     (pwd->pw_fields & _PWF_SOURCE) == _PWF_FILES)
 305                         /* root doesn't need the old password */
 306                         return (pam_set_item(pamh, PAM_OLDAUTHTOK, ""));
 307 #ifdef YP
 308                 if (getuid() == 0 &&
 309                     (pwd->pw_fields & _PWF_SOURCE) == _PWF_NIS) {
 310
 311                         yp_domain = yp_server = NULL;
 312                         (void)pam_get_data(pamh, "yp_domain", &yp_domain);
 313                         (void)pam_get_data(pamh, "yp_server", &yp_server);
 314
 315                         ypclnt = ypclnt_new(yp_domain, "passwd.byname", yp_server);
 316                         if (ypclnt == NULL)
 317                                 return (PAM_BUF_ERR);
 318
 319                         if (ypclnt_connect(ypclnt) == -1) {
 320                                 ypclnt_free(ypclnt);
 321                                 return (PAM_SERVICE_ERR);
 322                         }
 323
 324                         retval = ypclnt_havepasswdd(ypclnt);
 325                         ypclnt_free(ypclnt);
 326                         if (retval == 1)
 327                                 return (pam_set_item(pamh, PAM_OLDAUTHTOK, ""));
 328                         else if (retval == -1)
 329                                 return (PAM_SERVICE_ERR);
 330                 }
 331 #endif
 332                 if (pwd->pw_passwd[0] == '\0'
 333                     && openpam_get_option(pamh, PAM_OPT_NULLOK)) {
 334                         /*
 335                          * No password case. XXX Are we giving too much away
 336                          * by not prompting for a password?
 337                          * XXX check PAM_DISALLOW_NULL_AUTHTOK
 338                          */
 339                         old_pass = "";
 340                         retval = PAM_SUCCESS;
 341                 } else {
 342                         retval = pam_get_authtok(pamh,
 343                             PAM_OLDAUTHTOK, &old_pass, NULL);
 344                         if (retval != PAM_SUCCESS)
 345                                 return (retval);
 346                 }
 347                 PAM_LOG("Got old password");
 348                 /* always encrypt first */
 349                 encrypted = crypt(old_pass, pwd->pw_passwd);
 350                 if (old_pass[0] == '\0' &&
 351                     !openpam_get_option(pamh, PAM_OPT_NULLOK))
 352                         return (PAM_PERM_DENIED);
 353                 if (strcmp(encrypted, pwd->pw_passwd) != 0)
 354                         return (PAM_PERM_DENIED);
 355         }
 356         else if (flags & PAM_UPDATE_AUTHTOK) {
 357                 PAM_LOG("UPDATE round");
 358
 359                 retval = pam_get_authtok(pamh,
 360                     PAM_OLDAUTHTOK, &old_pass, NULL);
 361                 if (retval != PAM_SUCCESS)
 362                         return (retval);
 363                 PAM_LOG("Got old password");
 364
 365                 /* get new password */
 366                 for (;;) {
 367                         retval = pam_get_authtok(pamh,
 368                             PAM_AUTHTOK, &new_pass, NULL);
 369                         if (retval != PAM_TRY_AGAIN)
 370                                 break;
 371                         pam_error(pamh, "Mismatch; try again, EOF to quit.");
 372                 }
 373                 PAM_LOG("Got new password");
 374                 if (retval != PAM_SUCCESS) {
 375                         PAM_VERBOSE_ERROR("Unable to get new password");
 376                         return (retval);
 377                 }
 378
 379                 if (getuid() != 0 && new_pass[0] == '\0' &&
 380                     !openpam_get_option(pamh, PAM_OPT_NULLOK))
 381                         return (PAM_PERM_DENIED);
 382
 383                 if ((old_pwd = pw_dup(pwd)) == NULL)
 384                         return (PAM_BUF_ERR);
 385
 386                 lc = login_getclass(pwd->pw_class);
 387                 if (login_setcryptfmt(lc, password_hash, NULL) == NULL)
 388                         openpam_log(PAM_LOG_ERROR,
 389                             "can't set password cipher, relying on default");
 390
 391                 /* set password expiry date */
 392                 pwd->pw_change = 0;
 393                 passwordtime = login_getcaptime(lc, "passwordtime", 0, 0);
 394                 if (passwordtime > 0)
 395                         pwd->pw_change = time(NULL) + passwordtime;
 396
 397                 login_close(lc);
 398                 makesalt(salt);
 399                 pwd->pw_passwd = crypt(new_pass, salt);
 400 #ifdef YP
 401                 switch (old_pwd->pw_fields & _PWF_SOURCE) {
 402                 case _PWF_FILES:
 403 #endif
 404                         retval = PAM_SERVICE_ERR;
 405                         if (pw_init(NULL, NULL))
 406                                 openpam_log(PAM_LOG_ERROR, "pw_init() failed");
 407                         else if ((pfd = pw_lock()) == -1)
 408                                 openpam_log(PAM_LOG_ERROR, "pw_lock() failed");
 409                         else if ((tfd = pw_tmp(-1)) == -1)
 410                                 openpam_log(PAM_LOG_ERROR, "pw_tmp() failed");
 411                         else if (pw_copy(pfd, tfd, pwd, old_pwd) == -1)
 412                                 openpam_log(PAM_LOG_ERROR, "pw_copy() failed");
 413                         else if (pw_mkdb(pwd->pw_name) == -1)
 414                                 openpam_log(PAM_LOG_ERROR, "pw_mkdb() failed");
 415                         else
 416                                 retval = PAM_SUCCESS;
 417                         pw_fini();
 418 #ifdef YP
 419                         break;
 420                 case _PWF_NIS:
 421                         yp_domain = yp_server = NULL;
 422                         (void)pam_get_data(pamh, "yp_domain", &yp_domain);
 423                         (void)pam_get_data(pamh, "yp_server", &yp_server);
 424                         ypclnt = ypclnt_new(yp_domain,
 425                             "passwd.byname", yp_server);
 426                         if (ypclnt == NULL) {
 427                                 retval = PAM_BUF_ERR;
 428                         } else if (ypclnt_connect(ypclnt) == -1 ||
 429                             ypclnt_passwd(ypclnt, pwd, old_pass) == -1) {
 430                                 openpam_log(PAM_LOG_ERROR, "%s", ypclnt->error);
 431                                 retval = PAM_SERVICE_ERR;
 432                         } else {
 433                                 retval = PAM_SUCCESS;
 434                         }
 435                         ypclnt_free(ypclnt);
 436                         break;
 437                 default:
 438                         openpam_log(PAM_LOG_ERROR, "unsupported source 0x%x",
 439                             pwd->pw_fields & _PWF_SOURCE);
 440                         retval = PAM_SERVICE_ERR;
 441                 }
 442 #endif
 443                 free(old_pwd);
 444         }
 445         else {
 446                 /* Very bad juju */
 447                 retval = PAM_ABORT;
 448                 PAM_LOG("Illegal 'flags'");
 449         }
 450
 451         return (retval);
 452 }
 453
 454 /* Mostly stolen from passwd(1)'s local_passwd.c - markm */
 455
 456 static unsigned char itoa64[] =         /* 0 ... 63 => ascii - 64 */
 457         "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
 458
 459 static void
 460 to64(char *s, long v, int n)
 461 {
 462         while (--n >= 0) {
 463                 *s++ = itoa64[v&0x3f];
 464                 v >>= 6;
 465         }
 466 }
 467
 468 /* Salt suitable for traditional DES and MD5 */
 469 static void
 470 makesalt(char salt[SALTSIZE + 1])
 471 {
 472         int i;
 473
 474         /* These are not really random numbers, they are just
 475          * numbers that change to thwart construction of a
 476          * dictionary.
 477          */
 478         for (i = 0; i < SALTSIZE; i += 4)
 479                 to64(&salt[i], arc4random(), 4);
 480         salt[SALTSIZE] = '\0';
 481 }
 482
 483 PAM_MODULE_ENTRY("pam_unix");