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 <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           "md5"
  70 #define DEFAULT_WARN            (2L * 7L * 86400L)  /* Two weeks */
  71 #define SALTSIZE                32
  72
  73 static void makesalt(char []);
  74
  75 static char password_hash[] =           PASSWORD_HASH;
  76
  77 #define PAM_OPT_LOCAL_PASS      "local_pass"
  78 #define PAM_OPT_NIS_PASS        "nis_pass"
  79
  80 char *tempname = NULL;
  81
  82 /*
  83  * authentication management
  84  */
  85 PAM_EXTERN int
  86 pam_sm_authenticate(pam_handle_t *pamh, int flags __unused,
  87     int argc __unused, const char *argv[] __unused)
  88 {
  89         login_cap_t *lc;
  90         struct passwd *pwd;
  91         int retval;
  92         const char *pass, *user, *realpw, *prompt;
  93
  94         if (openpam_get_option(pamh, PAM_OPT_AUTH_AS_SELF)) {
  95                 pwd = getpwnam(getlogin());
  96         } else {
  97                 retval = pam_get_user(pamh, &user, NULL);
  98                 if (retval != PAM_SUCCESS)
  99                         return (retval);
 100                 pwd = getpwnam(user);
 101         }
 102
 103         PAM_LOG("Got user: %s", user);
 104
 105         if (pwd != NULL) {
 106                 PAM_LOG("Doing real authentication");
 107                 realpw = pwd->pw_passwd;
 108                 if (realpw[0] == '\0') {
 109                         if (!(flags & PAM_DISALLOW_NULL_AUTHTOK) &&
 110                             openpam_get_option(pamh, PAM_OPT_NULLOK))
 111                                 return (PAM_SUCCESS);
 112                         realpw = "*";
 113                 }
 114                 lc = login_getpwclass(pwd);
 115         } else {
 116                 PAM_LOG("Doing dummy authentication");
 117                 realpw = "*";
 118                 lc = login_getclass(NULL);
 119         }
 120         prompt = login_getcapstr(lc, "passwd_prompt", NULL, NULL);
 121         retval = pam_get_authtok(pamh, PAM_AUTHTOK, &pass, prompt);
 122         login_close(lc);
 123         if (retval != PAM_SUCCESS)
 124                 return (retval);
 125         PAM_LOG("Got password");
 126         if (strcmp(crypt(pass, realpw), realpw) == 0)
 127                 return (PAM_SUCCESS);
 128
 129         PAM_VERBOSE_ERROR("UNIX authentication refused");
 130         return (PAM_AUTH_ERR);
 131 }
 132
 133 PAM_EXTERN int
 134 pam_sm_setcred(pam_handle_t *pamh __unused, int flags __unused,
 135     int argc __unused, const char *argv[] __unused)
 136 {
 137
 138         return (PAM_SUCCESS);
 139 }
 140
 141 /*
 142  * account management
 143  */
 144 PAM_EXTERN int
 145 pam_sm_acct_mgmt(pam_handle_t *pamh, int flags __unused,
 146     int argc __unused, const char *argv[] __unused)
 147 {
 148         struct addrinfo hints, *res;
 149         struct passwd *pwd;
 150         struct timeval tp;
 151         login_cap_t *lc;
 152         time_t warntime;
 153         int retval;
 154         const char *user;
 155         const void *rhost, *tty;
 156         char rhostip[MAXHOSTNAMELEN] = "";
 157
 158         retval = pam_get_user(pamh, &user, NULL);
 159         if (retval != PAM_SUCCESS)
 160                 return (retval);
 161
 162         if (user == NULL || (pwd = getpwnam(user)) == NULL)
 163                 return (PAM_SERVICE_ERR);
 164
 165         PAM_LOG("Got user: %s", user);
 166
 167         retval = pam_get_item(pamh, PAM_RHOST, &rhost);
 168         if (retval != PAM_SUCCESS)
 169                 return (retval);
 170
 171         retval = pam_get_item(pamh, PAM_TTY, &tty);
 172         if (retval != PAM_SUCCESS)
 173                 return (retval);
 174
 175         if (*pwd->pw_passwd == '\0' &&
 176             (flags & PAM_DISALLOW_NULL_AUTHTOK) != 0)
 177                 return (PAM_NEW_AUTHTOK_REQD);
 178
 179         lc = login_getpwclass(pwd);
 180         if (lc == NULL) {
 181                 PAM_LOG("Unable to get login class for user %s", user);
 182                 return (PAM_SERVICE_ERR);
 183         }
 184
 185         PAM_LOG("Got login_cap");
 186
 187         if (pwd->pw_change || pwd->pw_expire)
 188                 gettimeofday(&tp, NULL);
 189
 190         /*
 191          * Check pw_expire before pw_change - no point in letting the
 192          * user change the password on an expired account.
 193          */
 194
 195         if (pwd->pw_expire) {
 196                 warntime = login_getcaptime(lc, "warnexpire",
 197                     DEFAULT_WARN, DEFAULT_WARN);
 198                 if (tp.tv_sec >= pwd->pw_expire) {
 199                         login_close(lc);
 200                         return (PAM_ACCT_EXPIRED);
 201                 } else if (pwd->pw_expire - tp.tv_sec < warntime &&
 202                     (flags & PAM_SILENT) == 0) {
 203                         pam_error(pamh, "Warning: your account expires on %s",
 204                             ctime(&pwd->pw_expire));
 205                 }
 206         }
 207
 208         retval = PAM_SUCCESS;
 209         if (pwd->pw_change) {
 210                 warntime = login_getcaptime(lc, "warnpassword",
 211                     DEFAULT_WARN, DEFAULT_WARN);
 212                 if (tp.tv_sec >= pwd->pw_change) {
 213                         retval = PAM_NEW_AUTHTOK_REQD;
 214                 } else if (pwd->pw_change - tp.tv_sec < warntime &&
 215                     (flags & PAM_SILENT) == 0) {
 216                         pam_error(pamh, "Warning: your password expires on %s",
 217                             ctime(&pwd->pw_change));
 218                 }
 219         }
 220
 221         /*
 222          * From here on, we must leave retval untouched (unless we
 223          * know we're going to fail), because we need to remember
 224          * whether we're supposed to return PAM_SUCCESS or
 225          * PAM_NEW_AUTHTOK_REQD.
 226          */
 227
 228         if (rhost && *(const char *)rhost != '\0') {
 229                 memset(&hints, 0, sizeof(hints));
 230                 hints.ai_family = AF_UNSPEC;
 231                 if (getaddrinfo(rhost, NULL, &hints, &res) == 0) {
 232                         getnameinfo(res->ai_addr, res->ai_addrlen,
 233                             rhostip, sizeof(rhostip), NULL, 0,
 234                             NI_NUMERICHOST);
 235                 }
 236                 if (res != NULL)
 237                         freeaddrinfo(res);
 238         }
 239
 240         /*
 241          * Check host / tty / time-of-day restrictions
 242          */
 243
 244         if (!auth_hostok(lc, rhost, rhostip) ||
 245             !auth_ttyok(lc, tty) ||
 246             !auth_timeok(lc, time(NULL)))
 247                 retval = PAM_AUTH_ERR;
 248
 249         login_close(lc);
 250
 251         return (retval);
 252 }
 253
 254 /*
 255  * password management
 256  *
 257  * standard Unix and NIS password changing
 258  */
 259 PAM_EXTERN int
 260 pam_sm_chauthtok(pam_handle_t *pamh, int flags,
 261     int argc __unused, const char *argv[] __unused)
 262 {
 263 #ifdef YP
 264         struct ypclnt *ypclnt;
 265         void *yp_domain, *yp_server;
 266 #endif
 267         char salt[SALTSIZE + 1];
 268         login_cap_t * lc;
 269         struct passwd *pwd, *old_pwd;
 270         const char *user, *old_pass, *new_pass;
 271         char *encrypted;
 272         int pfd, tfd, retval;
 273
 274         if (openpam_get_option(pamh, PAM_OPT_AUTH_AS_SELF))
 275                 pwd = getpwnam(getlogin());
 276         else {
 277                 retval = pam_get_user(pamh, &user, NULL);
 278                 if (retval != PAM_SUCCESS)
 279                         return (retval);
 280                 pwd = getpwnam(user);
 281         }
 282
 283         if (pwd == NULL)
 284                 return (PAM_AUTHTOK_RECOVERY_ERR);
 285
 286         PAM_LOG("Got user: %s", user);
 287
 288         if (flags & PAM_PRELIM_CHECK) {
 289
 290                 PAM_LOG("PRELIM round");
 291
 292                 if (getuid() == 0 &&
 293                     (pwd->pw_fields & _PWF_SOURCE) == _PWF_FILES)
 294                         /* root doesn't need the old password */
 295                         return (pam_set_item(pamh, PAM_OLDAUTHTOK, ""));
 296 #ifdef YP
 297                 if (getuid() == 0 &&
 298                     (pwd->pw_fields & _PWF_SOURCE) == _PWF_NIS) {
 299
 300                         yp_domain = yp_server = NULL;
 301                         (void)pam_get_data(pamh, "yp_domain", &yp_domain);
 302                         (void)pam_get_data(pamh, "yp_server", &yp_server);
 303
 304                         ypclnt = ypclnt_new(yp_domain, "passwd.byname", yp_server);
 305                         if (ypclnt == NULL)
 306                                 return (PAM_BUF_ERR);
 307
 308                         if (ypclnt_connect(ypclnt) == -1) {
 309                                 ypclnt_free(ypclnt);
 310                                 return (PAM_SERVICE_ERR);
 311                         }
 312
 313                         retval = ypclnt_havepasswdd(ypclnt);
 314                         ypclnt_free(ypclnt);
 315                         if (retval == 1)
 316                                 return (pam_set_item(pamh, PAM_OLDAUTHTOK, ""));
 317                         else if (retval == -1)
 318                                 return (PAM_SERVICE_ERR);
 319                 }
 320 #endif
 321                 if (pwd->pw_passwd[0] == '\0'
 322                     && openpam_get_option(pamh, PAM_OPT_NULLOK)) {
 323                         /*
 324                          * No password case. XXX Are we giving too much away
 325                          * by not prompting for a password?
 326                          * XXX check PAM_DISALLOW_NULL_AUTHTOK
 327                          */
 328                         old_pass = "";
 329                 } else {
 330                         retval = pam_get_authtok(pamh,
 331                             PAM_OLDAUTHTOK, &old_pass, NULL);
 332                         if (retval != PAM_SUCCESS)
 333                                 return (retval);
 334                 }
 335                 PAM_LOG("Got old password");
 336                 /* always encrypt first */
 337                 encrypted = crypt(old_pass, pwd->pw_passwd);
 338                 if (old_pass[0] == '\0' &&
 339                     !openpam_get_option(pamh, PAM_OPT_NULLOK))
 340                         return (PAM_PERM_DENIED);
 341                 if (strcmp(encrypted, pwd->pw_passwd) != 0)
 342                         return (PAM_PERM_DENIED);
 343         }
 344         else if (flags & PAM_UPDATE_AUTHTOK) {
 345                 PAM_LOG("UPDATE round");
 346
 347                 retval = pam_get_authtok(pamh,
 348                     PAM_OLDAUTHTOK, &old_pass, NULL);
 349                 if (retval != PAM_SUCCESS)
 350                         return (retval);
 351                 PAM_LOG("Got old password");
 352
 353                 /* get new password */
 354                 for (;;) {
 355                         retval = pam_get_authtok(pamh,
 356                             PAM_AUTHTOK, &new_pass, NULL);
 357                         if (retval != PAM_TRY_AGAIN)
 358                                 break;
 359                         pam_error(pamh, "Mismatch; try again, EOF to quit.");
 360                 }
 361                 PAM_LOG("Got new password");
 362                 if (retval != PAM_SUCCESS) {
 363                         PAM_VERBOSE_ERROR("Unable to get new password");
 364                         return (retval);
 365                 }
 366
 367                 if (getuid() != 0 && new_pass[0] == '\0' &&
 368                     !openpam_get_option(pamh, PAM_OPT_NULLOK))
 369                         return (PAM_PERM_DENIED);
 370
 371                 if ((old_pwd = pw_dup(pwd)) == NULL)
 372                         return (PAM_BUF_ERR);
 373
 374                 pwd->pw_change = 0;
 375                 lc = login_getclass(pwd->pw_class);
 376                 if (login_setcryptfmt(lc, password_hash, NULL) == NULL)
 377                         openpam_log(PAM_LOG_ERROR,
 378                             "can't set password cipher, relying on default");
 379                 login_close(lc);
 380                 makesalt(salt);
 381                 pwd->pw_passwd = crypt(new_pass, salt);
 382 #ifdef YP
 383                 switch (old_pwd->pw_fields & _PWF_SOURCE) {
 384                 case _PWF_FILES:
 385 #endif
 386                         retval = PAM_SERVICE_ERR;
 387                         if (pw_init(NULL, NULL))
 388                                 openpam_log(PAM_LOG_ERROR, "pw_init() failed");
 389                         else if ((pfd = pw_lock()) == -1)
 390                                 openpam_log(PAM_LOG_ERROR, "pw_lock() failed");
 391                         else if ((tfd = pw_tmp(-1)) == -1)
 392                                 openpam_log(PAM_LOG_ERROR, "pw_tmp() failed");
 393                         else if (pw_copy(pfd, tfd, pwd, old_pwd) == -1)
 394                                 openpam_log(PAM_LOG_ERROR, "pw_copy() failed");
 395                         else if (pw_mkdb(pwd->pw_name) == -1)
 396                                 openpam_log(PAM_LOG_ERROR, "pw_mkdb() failed");
 397                         else
 398                                 retval = PAM_SUCCESS;
 399                         pw_fini();
 400 #ifdef YP
 401                         break;
 402                 case _PWF_NIS:
 403                         yp_domain = yp_server = NULL;
 404                         (void)pam_get_data(pamh, "yp_domain", &yp_domain);
 405                         (void)pam_get_data(pamh, "yp_server", &yp_server);
 406                         ypclnt = ypclnt_new(yp_domain,
 407                             "passwd.byname", yp_server);
 408                         if (ypclnt == NULL) {
 409                                 retval = PAM_BUF_ERR;
 410                         } else if (ypclnt_connect(ypclnt) == -1 ||
 411                             ypclnt_passwd(ypclnt, pwd, old_pass) == -1) {
 412                                 openpam_log(PAM_LOG_ERROR, "%s", ypclnt->error);
 413                                 retval = PAM_SERVICE_ERR;
 414                         } else {
 415                                 retval = PAM_SUCCESS;
 416                         }
 417                         ypclnt_free(ypclnt);
 418                         break;
 419                 default:
 420                         openpam_log(PAM_LOG_ERROR, "unsupported source 0x%x",
 421                             pwd->pw_fields & _PWF_SOURCE);
 422                         retval = PAM_SERVICE_ERR;
 423                 }
 424 #endif
 425                 free(old_pwd);
 426         }
 427         else {
 428                 /* Very bad juju */
 429                 retval = PAM_ABORT;
 430                 PAM_LOG("Illegal 'flags'");
 431         }
 432
 433         return (retval);
 434 }
 435
 436 /* Mostly stolen from passwd(1)'s local_passwd.c - markm */
 437
 438 static unsigned char itoa64[] =         /* 0 ... 63 => ascii - 64 */
 439         "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
 440
 441 static void
 442 to64(char *s, long v, int n)
 443 {
 444         while (--n >= 0) {
 445                 *s++ = itoa64[v&0x3f];
 446                 v >>= 6;
 447         }
 448 }
 449
 450 /* Salt suitable for traditional DES and MD5 */
 451 void
 452 makesalt(char salt[SALTSIZE])
 453 {
 454         int i;
 455
 456         /* These are not really random numbers, they are just
 457          * numbers that change to thwart construction of a
 458          * dictionary. This is exposed to the public.
 459          */
 460         for (i = 0; i < SALTSIZE; i += 4)
 461                 to64(&salt[i], arc4random(), 4);
 462         salt[SALTSIZE] = '\0';
 463 }
 464
 465 PAM_MODULE_ENTRY("pam_unix");