lib/pam_module/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  * $FreeBSD: src/lib/libpam/modules/pam_unix/pam_unix.c,v 1.56 2011/11/05 10:00:29 ed Exp $
  37  */
  38
  39 #include <sys/param.h>
  40 #include <sys/socket.h>
  41 #include <sys/time.h>
  42 #include <netinet/in.h>
  43 #include <arpa/inet.h>
  44
  45 #include <login_cap.h>
  46 #include <netdb.h>
  47 #include <pwd.h>
  48 #include <stdlib.h>
  49 #include <string.h>
  50 #include <stdio.h>
  51 #include <syslog.h>
  52 #include <time.h>
  53 #include <unistd.h>
  54
  55 #include <libutil.h>
  56
  57 #ifdef YP
  58 #include <ypclnt.h>
  59 #endif
  60
  61 #define PAM_SM_AUTH
  62 #define PAM_SM_ACCOUNT
  63 #define PAM_SM_PASSWORD
  64
  65 #include <security/pam_appl.h>
  66 #include <security/pam_modules.h>
  67 #include <security/pam_mod_misc.h>
  68
  69 #define PASSWORD_HASH           "sha512"
  70 #define DEFAULT_WARN            (2L * 7L * 86400L)  /* Two weeks */
  71 #define SALTSIZE                32
  72
  73 #define LOCKED_PREFIX           "*LOCKED*"
  74 #define LOCKED_PREFIX_LEN       (sizeof(LOCKED_PREFIX) - 1)
  75
  76 static void makesalt(char []);
  77
  78 static char password_hash[] =           PASSWORD_HASH;
  79
  80 #define PAM_OPT_LOCAL_PASS      "local_pass"
  81 #define PAM_OPT_NIS_PASS        "nis_pass"
  82
  83 /*
  84  * authentication management
  85  */
  86 PAM_EXTERN int
  87 pam_sm_authenticate(pam_handle_t *pamh, int flags __unused,
  88     int argc __unused, const char *argv[] __unused)
  89 {
  90         login_cap_t *lc;
  91         struct passwd *pwd;
  92         int retval;
  93         const char *pass, *user, *realpw, *prompt;
  94
  95         if (openpam_get_option(pamh, PAM_OPT_AUTH_AS_SELF)) {
  96                 pwd = getpwnam(getlogin());
  97         } else {
  98                 retval = pam_get_user(pamh, &user, NULL);
  99                 if (retval != PAM_SUCCESS)
 100                         return (retval);
 101                 pwd = getpwnam(user);
 102         }
 103
 104         PAM_LOG("Got user: %s", user);
 105
 106         if (pwd != NULL) {
 107                 PAM_LOG("Doing real authentication");
 108                 realpw = pwd->pw_passwd;
 109                 if (realpw[0] == '\0') {
 110                         if (!(flags & PAM_DISALLOW_NULL_AUTHTOK) &&
 111                             openpam_get_option(pamh, PAM_OPT_NULLOK))
 112                                 return (PAM_SUCCESS);
 113                         realpw = "*";
 114                 }
 115                 lc = login_getpwclass(pwd);
 116         } else {
 117                 PAM_LOG("Doing dummy authentication");
 118                 realpw = "*";
 119                 lc = login_getclass(NULL);
 120         }
 121         prompt = login_getcapstr(lc, "passwd_prompt", NULL, NULL);
 122         retval = pam_get_authtok(pamh, PAM_AUTHTOK, &pass, prompt);
 123         login_close(lc);
 124         if (retval != PAM_SUCCESS)
 125                 return (retval);
 126         PAM_LOG("Got password");
 127         if (strcmp(crypt(pass, realpw), realpw) == 0)
 128                 return (PAM_SUCCESS);
 129
 130         PAM_VERBOSE_ERROR("UNIX authentication refused");
 131         return (PAM_AUTH_ERR);
 132 }
 133
 134 PAM_EXTERN int
 135 pam_sm_setcred(pam_handle_t *pamh __unused, int flags __unused,
 136     int argc __unused, const char *argv[] __unused)
 137 {
 138
 139         return (PAM_SUCCESS);
 140 }
 141
 142 /*
 143  * account management
 144  */
 145 PAM_EXTERN int
 146 pam_sm_acct_mgmt(pam_handle_t *pamh, int flags __unused,
 147     int argc __unused, const char *argv[] __unused)
 148 {
 149         struct addrinfo hints, *res;
 150         struct passwd *pwd;
 151         struct timeval tp;
 152         login_cap_t *lc;
 153         time_t warntime;
 154         int retval;
 155         const char *user;
 156         const void *rhost, *tty;
 157         char rhostip[MAXHOSTNAMELEN] = "";
 158
 159         retval = pam_get_user(pamh, &user, NULL);
 160         if (retval != PAM_SUCCESS)
 161                 return (retval);
 162
 163         if (user == NULL || (pwd = getpwnam(user)) == NULL)
 164                 return (PAM_SERVICE_ERR);
 165
 166         PAM_LOG("Got user: %s", user);
 167
 168         retval = pam_get_item(pamh, PAM_RHOST, &rhost);
 169         if (retval != PAM_SUCCESS)
 170                 return (retval);
 171
 172         retval = pam_get_item(pamh, PAM_TTY, &tty);
 173         if (retval != PAM_SUCCESS)
 174                 return (retval);
 175
 176         if (*pwd->pw_passwd == '\0' &&
 177             (flags & PAM_DISALLOW_NULL_AUTHTOK) != 0)
 178                 return (PAM_NEW_AUTHTOK_REQD);
 179
 180         if (strncmp(pwd->pw_passwd, LOCKED_PREFIX, LOCKED_PREFIX_LEN) == 0)
 181                 return (PAM_AUTH_ERR);
 182
 183         lc = login_getpwclass(pwd);
 184         if (lc == NULL) {
 185                 PAM_LOG("Unable to get login class for user %s", user);
 186                 return (PAM_SERVICE_ERR);
 187         }
 188
 189         PAM_LOG("Got login_cap");
 190
 191         if (pwd->pw_change || pwd->pw_expire)
 192                 gettimeofday(&tp, NULL);
 193
 194         /*
 195          * Check pw_expire before pw_change - no point in letting the
 196          * user change the password on an expired account.
 197          */
 198
 199         if (pwd->pw_expire) {
 200                 warntime = login_getcaptime(lc, "warnexpire",
 201                     DEFAULT_WARN, DEFAULT_WARN);
 202                 if (tp.tv_sec >= pwd->pw_expire) {
 203                         login_close(lc);
 204                         return (PAM_ACCT_EXPIRED);
 205                 } else if (pwd->pw_expire - tp.tv_sec < warntime &&
 206                     (flags & PAM_SILENT) == 0) {
 207                         pam_error(pamh, "Warning: your account expires on %s",
 208                             ctime(&pwd->pw_expire));
 209                 }
 210         }
 211
 212         retval = PAM_SUCCESS;
 213         if (pwd->pw_change) {
 214                 warntime = login_getcaptime(lc, "warnpassword",
 215                     DEFAULT_WARN, DEFAULT_WARN);
 216                 if (tp.tv_sec >= pwd->pw_change) {
 217                         retval = PAM_NEW_AUTHTOK_REQD;
 218                 } else if (pwd->pw_change - tp.tv_sec < warntime &&
 219                     (flags & PAM_SILENT) == 0) {
 220                         pam_error(pamh, "Warning: your password expires on %s",
 221                             ctime(&pwd->pw_change));
 222                 }
 223         }
 224
 225         /*
 226          * From here on, we must leave retval untouched (unless we
 227          * know we're going to fail), because we need to remember
 228          * whether we're supposed to return PAM_SUCCESS or
 229          * PAM_NEW_AUTHTOK_REQD.
 230          */
 231
 232         if (rhost && *(const char *)rhost != '\0') {
 233                 memset(&hints, 0, sizeof(hints));
 234                 hints.ai_family = AF_UNSPEC;
 235                 if (getaddrinfo(rhost, NULL, &hints, &res) == 0) {
 236                         getnameinfo(res->ai_addr, res->ai_addrlen,
 237                             rhostip, sizeof(rhostip), NULL, 0,
 238                             NI_NUMERICHOST);
 239                 }
 240                 if (res != NULL)
 241                         freeaddrinfo(res);
 242         }
 243
 244         /*
 245          * Check host / tty / time-of-day restrictions
 246          */
 247
 248         if (!auth_hostok(lc, rhost, rhostip) ||
 249             !auth_ttyok(lc, tty) ||
 250             !auth_timeok(lc, time(NULL)))
 251                 retval = PAM_AUTH_ERR;
 252
 253         login_close(lc);
 254
 255         return (retval);
 256 }
 257
 258 /*
 259  * password management
 260  *
 261  * standard Unix and NIS password changing
 262  */
 263 PAM_EXTERN int
 264 pam_sm_chauthtok(pam_handle_t *pamh, int flags,
 265     int argc __unused, const char *argv[] __unused)
 266 {
 267 #ifdef YP
 268         struct ypclnt *ypclnt;
 269         const void *yp_domain, *yp_server;
 270 #endif
 271         char salt[SALTSIZE + 1];
 272         login_cap_t *lc;
 273         struct passwd *pwd, *old_pwd;
 274         const char *user, *old_pass, *new_pass;
 275         char *encrypted;
 276         time_t passwordtime;
 277         int pfd, tfd, retval;
 278
 279         if (openpam_get_option(pamh, PAM_OPT_AUTH_AS_SELF))
 280                 pwd = getpwnam(getlogin());
 281         else {
 282                 retval = pam_get_user(pamh, &user, NULL);
 283                 if (retval != PAM_SUCCESS)
 284                         return (retval);
 285                 pwd = getpwnam(user);
 286         }
 287
 288         if (pwd == NULL)
 289                 return (PAM_AUTHTOK_RECOVERY_ERR);
 290
 291         PAM_LOG("Got user: %s", user);
 292
 293         if (flags & PAM_PRELIM_CHECK) {
 294
 295                 PAM_LOG("PRELIM round");
 296
 297                 if (getuid() == 0 &&
 298                     (pwd->pw_fields & _PWF_SOURCE) == _PWF_FILES)
 299                         /* root doesn't need the old password */
 300                         return (pam_set_item(pamh, PAM_OLDAUTHTOK, ""));
 301 #ifdef YP
 302                 if (getuid() == 0 &&
 303                     (pwd->pw_fields & _PWF_SOURCE) == _PWF_NIS) {
 304
 305                         yp_domain = yp_server = NULL;
 306                         pam_get_data(pamh, "yp_domain", &yp_domain);
 307                         pam_get_data(pamh, "yp_server", &yp_server);
 308
 309                         ypclnt = ypclnt_new(yp_domain, "passwd.byname", yp_server);
 310                         if (ypclnt == NULL)
 311                                 return (PAM_BUF_ERR);
 312
 313                         if (ypclnt_connect(ypclnt) == -1) {
 314                                 ypclnt_free(ypclnt);
 315                                 return (PAM_SERVICE_ERR);
 316                         }
 317
 318                         retval = ypclnt_havepasswdd(ypclnt);
 319                         ypclnt_free(ypclnt);
 320                         if (retval == 1)
 321                                 return (pam_set_item(pamh, PAM_OLDAUTHTOK, ""));
 322                         else if (retval == -1)
 323                                 return (PAM_SERVICE_ERR);
 324                 }
 325 #endif
 326                 if (pwd->pw_passwd[0] == '\0'
 327                     && openpam_get_option(pamh, PAM_OPT_NULLOK)) {
 328                         /*
 329                          * No password case. XXX Are we giving too much away
 330                          * by not prompting for a password?
 331                          * XXX check PAM_DISALLOW_NULL_AUTHTOK
 332                          */
 333                         old_pass = "";
 334                 } else {
 335                         retval = pam_get_authtok(pamh,
 336                             PAM_OLDAUTHTOK, &old_pass, NULL);
 337                         if (retval != PAM_SUCCESS)
 338                                 return (retval);
 339                 }
 340                 PAM_LOG("Got old password");
 341                 /* always encrypt first */
 342                 encrypted = crypt(old_pass, pwd->pw_passwd);
 343                 if (old_pass[0] == '\0' &&
 344                     !openpam_get_option(pamh, PAM_OPT_NULLOK))
 345                         return (PAM_PERM_DENIED);
 346                 if (strcmp(encrypted, pwd->pw_passwd) != 0)
 347                         return (PAM_PERM_DENIED);
 348         }
 349         else if (flags & PAM_UPDATE_AUTHTOK) {
 350                 PAM_LOG("UPDATE round");
 351
 352                 retval = pam_get_authtok(pamh,
 353                     PAM_OLDAUTHTOK, &old_pass, NULL);
 354                 if (retval != PAM_SUCCESS)
 355                         return (retval);
 356                 PAM_LOG("Got old password");
 357
 358                 /* get new password */
 359                 for (;;) {
 360                         retval = pam_get_authtok(pamh,
 361                             PAM_AUTHTOK, &new_pass, NULL);
 362                         if (retval != PAM_TRY_AGAIN)
 363                                 break;
 364                         pam_error(pamh, "Mismatch; try again, EOF to quit.");
 365                 }
 366                 PAM_LOG("Got new password");
 367                 if (retval != PAM_SUCCESS) {
 368                         PAM_VERBOSE_ERROR("Unable to get new password");
 369                         return (retval);
 370                 }
 371
 372                 if (getuid() != 0 && new_pass[0] == '\0' &&
 373                     !openpam_get_option(pamh, PAM_OPT_NULLOK))
 374                         return (PAM_PERM_DENIED);
 375
 376                 if ((old_pwd = pw_dup(pwd)) == NULL)
 377                         return (PAM_BUF_ERR);
 378
 379                 lc = login_getclass(pwd->pw_class);
 380                 if (login_setcryptfmt(lc, password_hash, NULL) == NULL)
 381                         openpam_log(PAM_LOG_ERROR,
 382                             "can't set password cipher, relying on default");
 383
 384                 /* set password expiry date */
 385                 pwd->pw_change = 0;
 386                 passwordtime = login_getcaptime(lc, "passwordtime", 0, 0);
 387                 if (passwordtime > 0)
 388                         pwd->pw_change = time(NULL) + passwordtime;
 389
 390                 login_close(lc);
 391                 makesalt(salt);
 392                 pwd->pw_passwd = crypt(new_pass, salt);
 393 #ifdef YP
 394                 switch (old_pwd->pw_fields & _PWF_SOURCE) {
 395                 case _PWF_FILES:
 396 #endif
 397                         retval = PAM_SERVICE_ERR;
 398                         if (pw_init(NULL, NULL))
 399                                 openpam_log(PAM_LOG_ERROR, "pw_init() failed");
 400                         else if ((pfd = pw_lock()) == -1)
 401                                 openpam_log(PAM_LOG_ERROR, "pw_lock() failed");
 402                         else if ((tfd = pw_tmp(-1)) == -1)
 403                                 openpam_log(PAM_LOG_ERROR, "pw_tmp() failed");
 404                         else if (pw_copy(pfd, tfd, pwd, old_pwd) == -1)
 405                                 openpam_log(PAM_LOG_ERROR, "pw_copy() failed");
 406                         else if (pw_mkdb(pwd->pw_name) == -1)
 407                                 openpam_log(PAM_LOG_ERROR, "pw_mkdb() failed");
 408                         else
 409                                 retval = PAM_SUCCESS;
 410                         pw_fini();
 411 #ifdef YP
 412                         break;
 413                 case _PWF_NIS:
 414                         yp_domain = yp_server = NULL;
 415                         pam_get_data(pamh, "yp_domain", &yp_domain);
 416                         pam_get_data(pamh, "yp_server", &yp_server);
 417                         ypclnt = ypclnt_new(yp_domain,
 418                             "passwd.byname", yp_server);
 419                         if (ypclnt == NULL) {
 420                                 retval = PAM_BUF_ERR;
 421                         } else if (ypclnt_connect(ypclnt) == -1 ||
 422                             ypclnt_passwd(ypclnt, pwd, old_pass) == -1) {
 423                                 openpam_log(PAM_LOG_ERROR, "%s", ypclnt->error);
 424                                 retval = PAM_SERVICE_ERR;
 425                         } else {
 426                                 retval = PAM_SUCCESS;
 427                         }
 428                         ypclnt_free(ypclnt);
 429                         break;
 430                 default:
 431                         openpam_log(PAM_LOG_ERROR, "unsupported source 0x%x",
 432                             pwd->pw_fields & _PWF_SOURCE);
 433                         retval = PAM_SERVICE_ERR;
 434                 }
 435 #endif
 436                 free(old_pwd);
 437         }
 438         else {
 439                 /* Very bad juju */
 440                 retval = PAM_ABORT;
 441                 PAM_LOG("Illegal 'flags'");
 442         }
 443
 444         return (retval);
 445 }
 446
 447 /* Mostly stolen from passwd(1)'s local_passwd.c - markm */
 448
 449 static unsigned char itoa64[] =         /* 0 ... 63 => ascii - 64 */
 450         "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
 451
 452 static void
 453 to64(char *s, long v, int n)
 454 {
 455         while (--n >= 0) {
 456                 *s++ = itoa64[v&0x3f];
 457                 v >>= 6;
 458         }
 459 }
 460
 461 /* Salt suitable for traditional DES and MD5 */
 462 void
 463 makesalt(char salt[SALTSIZE])
 464 {
 465         int i;
 466
 467         /* These are not really random numbers, they are just
 468          * numbers that change to thwart construction of a
 469          * dictionary. This is exposed to the public.
 470          */
 471         for (i = 0; i < SALTSIZE; i += 4)
 472                 to64(&salt[i], arc4random(), 4);
 473         salt[SALTSIZE] = '\0';
 474 }
 475
 476 PAM_MODULE_ENTRY("pam_unix");