usr.bin/su/su.c

   1 /*
   2  * Copyright (c) 2002, 2005 Networks Associates Technologies, Inc.
   3  * All rights reserved.
   4  *
   5  * Portions of this software were developed for the FreeBSD Project by
   6  * ThinkSec AS and NAI Labs, the Security Research Division of Network
   7  * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
   8  * ("CBOSS"), as part of the DARPA CHATS research program.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31 /*-
  32  * Copyright (c) 1988, 1993, 1994
  33  *      The Regents of the University of California.  All rights reserved.
  34  *
  35  * Redistribution and use in source and binary forms, with or without
  36  * modification, are permitted provided that the following conditions
  37  * are met:
  38  * 1. Redistributions of source code must retain the above copyright
  39  *    notice, this list of conditions and the following disclaimer.
  40  * 2. Redistributions in binary form must reproduce the above copyright
  41  *    notice, this list of conditions and the following disclaimer in the
  42  *    documentation and/or other materials provided with the distribution.
  43  * 3. All advertising materials mentioning features or use of this software
  44  *    must display the following acknowledgement:
  45  *      This product includes software developed by the University of
  46  *      California, Berkeley and its contributors.
  47  * 4. Neither the name of the University nor the names of its contributors
  48  *    may be used to endorse or promote products derived from this software
  49  *    without specific prior written permission.
  50  *
  51  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  52  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  53  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  54  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  55  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  56  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  57  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  58  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  59  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  60  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  61  * SUCH DAMAGE.
  62  *
  63  * @(#)su.c     8.3 (Berkeley) 4/2/94
  64  * $FreeBSD: src/usr.bin/su/su.c,v 1.88 2008/06/04 19:16:54 dwmalone Exp $
  65  * $DragonFly: src/usr.bin/su/su.c,v 1.9 2006/01/12 13:43:11 corecode Exp $
  66  */
  67
  68 #include <sys/param.h>
  69 #include <sys/time.h>
  70 #include <sys/resource.h>
  71 #include <sys/wait.h>
  72
  73 #ifdef USE_BSM_AUDIT
  74 #include <bsm/libbsm.h>
  75 #include <bsm/audit_uevents.h>
  76 #endif
  77
  78 #include <err.h>
  79 #include <errno.h>
  80 #include <grp.h>
  81 #include <login_cap.h>
  82 #include <paths.h>
  83 #include <pwd.h>
  84 #include <signal.h>
  85 #include <stdio.h>
  86 #include <stdlib.h>
  87 #include <string.h>
  88 #include <syslog.h>
  89 #include <unistd.h>
  90 #include <stdarg.h>
  91
  92 #include <security/pam_appl.h>
  93 #include <security/openpam.h>
  94
  95 #define PAM_END() do {                                                  \
  96         int local_ret;                                                  \
  97         if (pamh != NULL) {                                             \
  98                 local_ret = pam_setcred(pamh, PAM_DELETE_CRED);         \
  99                 if (local_ret != PAM_SUCCESS)                           \
 100                         syslog(LOG_ERR, "pam_setcred: %s",              \
 101                                 pam_strerror(pamh, local_ret));         \
 102                 if (asthem) {                                           \
 103                         local_ret = pam_close_session(pamh, 0);         \
 104                         if (local_ret != PAM_SUCCESS)                   \
 105                                 syslog(LOG_ERR, "pam_close_session: %s",\
 106                                         pam_strerror(pamh, local_ret)); \
 107                 }                                                       \
 108                 local_ret = pam_end(pamh, local_ret);                   \
 109                 if (local_ret != PAM_SUCCESS)                           \
 110                         syslog(LOG_ERR, "pam_end: %s",                  \
 111                                 pam_strerror(pamh, local_ret));         \
 112         }                                                               \
 113 } while (0)
 114
 115
 116 #define PAM_SET_ITEM(what, item) do {                                   \
 117         int local_ret;                                                  \
 118         local_ret = pam_set_item(pamh, what, item);                     \
 119         if (local_ret != PAM_SUCCESS) {                                 \
 120                 syslog(LOG_ERR, "pam_set_item(" #what "): %s",          \
 121                         pam_strerror(pamh, local_ret));                 \
 122                 errx(1, "pam_set_item(" #what "): %s",                  \
 123                         pam_strerror(pamh, local_ret));                 \
 124                 /* NOTREACHED */                                        \
 125         }                                                               \
 126 } while (0)
 127
 128 enum tristate { UNSET, YES, NO };
 129
 130 static pam_handle_t *pamh = NULL;
 131 static char     **environ_pam;
 132
 133 static char     *ontty(void);
 134 static int      chshell(const char *);
 135 static void     usage(void) __dead2;
 136 static void     export_pam_environment(void);
 137 static int      ok_to_export(const char *);
 138
 139 extern char     **environ;
 140
 141 int
 142 main(int argc, char **argv)
 143 {
 144         static char     *cleanenv;
 145         struct passwd   *pwd;
 146         struct pam_conv conv = { openpam_ttyconv, NULL };
 147         enum tristate   iscsh;
 148         login_cap_t     *lc;
 149         union {
 150                 const char      **a;
 151                 char            * const *b;
 152         }               np;
 153         uid_t           ruid;
 154         pid_t           child_pid, child_pgrp, pid;
 155         int             asme, ch, asthem, fastlogin, prio, i, retcode,
 156                         statusp;
 157         u_int           setwhat;
 158         char            *username, *class, shellbuf[MAXPATHLEN];
 159         const char      *p = p, *user, *shell, *mytty, **nargv;
 160         const void      *v;
 161         struct sigaction sa, sa_int, sa_quit, sa_pipe;
 162         int temp, fds[2];
 163 #ifdef USE_BSM_AUDIT
 164         const char      *aerr;
 165         au_id_t          auid;
 166 #endif
 167
 168         shell = class = cleanenv = NULL;
 169         asme = asthem = fastlogin = statusp = 0;
 170         user = "root";
 171         iscsh = UNSET;
 172
 173         while ((ch = getopt(argc, argv, "-flmc:")) != -1)
 174                 switch ((char)ch) {
 175                 case 'f':
 176                         fastlogin = 1;
 177                         break;
 178                 case '-':
 179                 case 'l':
 180                         asme = 0;
 181                         asthem = 1;
 182                         break;
 183                 case 'm':
 184                         asme = 1;
 185                         asthem = 0;
 186                         break;
 187                 case 'c':
 188                         class = optarg;
 189                         break;
 190                 case '?':
 191                 default:
 192                         usage();
 193                 /* NOTREACHED */
 194                 }
 195
 196         if (optind < argc && strcmp(argv[optind], "-") == 0) {
 197                 asme = 0;
 198                 asthem = 1;
 199                 optind++;
 200         }
 201
 202         if (optind < argc)
 203                 user = argv[optind++];
 204
 205         if (user == NULL)
 206                 usage();
 207         /* NOTREACHED */
 208
 209         /*
 210          * Try to provide more helpful debugging output if su(1) is running
 211          * non-setuid, or was run from a file system not mounted setuid.
 212          */
 213         if (geteuid() != 0)
 214                 errx(1, "not running setuid");
 215
 216 #ifdef USE_BSM_AUDIT
 217         if (getauid(&auid) < 0 && errno != ENOSYS) {
 218                 syslog(LOG_AUTH | LOG_ERR, "getauid: %s", strerror(errno));
 219                 errx(1, "Permission denied");
 220         }
 221 #endif
 222         if (strlen(user) > MAXLOGNAME - 1) {
 223 #ifdef USE_BSM_AUDIT
 224                 if (audit_submit(AUE_su, auid,
 225                     1, EPERM, "username too long: '%s'", user))
 226                         errx(1, "Permission denied");
 227 #endif
 228                 errx(1, "username too long");
 229         }
 230
 231         nargv = malloc(sizeof(char *) * (size_t)(argc + 4));
 232         if (nargv == NULL)
 233                 errx(1, "malloc failure");
 234
 235         nargv[argc + 3] = NULL;
 236         for (i = argc; i >= optind; i--)
 237                 nargv[i + 3] = argv[i];
 238         np.a = &nargv[i + 3];
 239
 240         argv += optind;
 241
 242         errno = 0;
 243         prio = getpriority(PRIO_PROCESS, 0);
 244         if (errno)
 245                 prio = 0;
 246
 247         setpriority(PRIO_PROCESS, 0, -2);
 248         openlog("su", LOG_CONS, LOG_AUTH);
 249
 250         /* get current login name, real uid and shell */
 251         ruid = getuid();
 252         username = getlogin();
 253         pwd = getpwnam(username);
 254         if (username == NULL || pwd == NULL || pwd->pw_uid != ruid)
 255                 pwd = getpwuid(ruid);
 256         if (pwd == NULL) {
 257 #ifdef USE_BSM_AUDIT
 258                 if (audit_submit(AUE_su, auid, 1, EPERM,
 259                     "unable to determine invoking subject: '%s'", username))
 260                         errx(1, "Permission denied");
 261 #endif
 262                 errx(1, "who are you?");
 263         }
 264
 265         username = strdup(pwd->pw_name);
 266         if (username == NULL)
 267                 err(1, "strdup failure");
 268
 269         if (asme) {
 270                 if (pwd->pw_shell != NULL && *pwd->pw_shell != '\0') {
 271                         /* must copy - pwd memory is recycled */
 272                         shell = strncpy(shellbuf, pwd->pw_shell,
 273                             sizeof(shellbuf));
 274                         shellbuf[sizeof(shellbuf) - 1] = '\0';
 275                 }
 276                 else {
 277                         shell = _PATH_BSHELL;
 278                         iscsh = NO;
 279                 }
 280         }
 281
 282         /* Do the whole PAM startup thing */
 283         retcode = pam_start("su", user, &conv, &pamh);
 284         if (retcode != PAM_SUCCESS) {
 285                 syslog(LOG_ERR, "pam_start: %s", pam_strerror(pamh, retcode));
 286                 errx(1, "pam_start: %s", pam_strerror(pamh, retcode));
 287         }
 288
 289         PAM_SET_ITEM(PAM_RUSER, username);
 290
 291         mytty = ttyname(STDERR_FILENO);
 292         if (!mytty)
 293                 mytty = "tty";
 294         PAM_SET_ITEM(PAM_TTY, mytty);
 295
 296         retcode = pam_authenticate(pamh, 0);
 297         if (retcode != PAM_SUCCESS) {
 298 #ifdef USE_BSM_AUDIT
 299                 if (audit_submit(AUE_su, auid, 1, EPERM, "bad su %s to %s on %s",
 300                     username, user, mytty))
 301                         errx(1, "Permission denied");
 302 #endif
 303                 syslog(LOG_AUTH|LOG_WARNING, "BAD SU %s to %s on %s",
 304                     username, user, mytty);
 305                 errx(1, "Sorry");
 306         }
 307 #ifdef USE_BSM_AUDIT
 308         if (audit_submit(AUE_su, auid, 0, 0, "successful authentication"))
 309                 errx(1, "Permission denied");
 310 #endif
 311         retcode = pam_get_item(pamh, PAM_USER, &v);
 312         if (retcode == PAM_SUCCESS)
 313                 user = v;
 314         else
 315                 syslog(LOG_ERR, "pam_get_item(PAM_USER): %s",
 316                     pam_strerror(pamh, retcode));
 317         pwd = getpwnam(user);
 318         if (pwd == NULL) {
 319 #ifdef USE_BSM_AUDIT
 320                 if (audit_submit(AUE_su, auid, 1, EPERM,
 321                     "unknown subject: %s", user))
 322                         errx(1, "Permission denied");
 323 #endif
 324                 errx(1, "unknown login: %s", user);
 325         }
 326
 327         retcode = pam_acct_mgmt(pamh, 0);
 328         if (retcode == PAM_NEW_AUTHTOK_REQD) {
 329                 retcode = pam_chauthtok(pamh,
 330                         PAM_CHANGE_EXPIRED_AUTHTOK);
 331                 if (retcode != PAM_SUCCESS) {
 332 #ifdef USE_BSM_AUDIT
 333                         aerr = pam_strerror(pamh, retcode);
 334                         if (aerr == NULL)
 335                                 aerr = "Unknown PAM error";
 336                         if (audit_submit(AUE_su, auid, 1, EPERM,
 337                             "pam_chauthtok: %s", aerr))
 338                                 errx(1, "Permission denied");
 339 #endif
 340                         syslog(LOG_ERR, "pam_chauthtok: %s",
 341                             pam_strerror(pamh, retcode));
 342                         errx(1, "Sorry");
 343                 }
 344         }
 345         if (retcode != PAM_SUCCESS) {
 346 #ifdef USE_BSM_AUDIT
 347                 if (audit_submit(AUE_su, auid, 1, EPERM, "pam_acct_mgmt: %s",
 348                     pam_strerror(pamh, retcode)))
 349                         errx(1, "Permission denied");
 350 #endif
 351                 syslog(LOG_ERR, "pam_acct_mgmt: %s",
 352                         pam_strerror(pamh, retcode));
 353                 errx(1, "Sorry");
 354         }
 355
 356         /* get target login information */
 357         if (class == NULL)
 358                 lc = login_getpwclass(pwd);
 359         else {
 360                 if (ruid != 0) {
 361 #ifdef USE_BSM_AUDIT
 362                         if (audit_submit(AUE_su, auid, 1, EPERM,
 363                             "only root may use -c"))
 364                                 errx(1, "Permission denied");
 365 #endif
 366                         errx(1, "only root may use -c");
 367                 }
 368                 lc = login_getclass(class);
 369                 if (lc == NULL)
 370                         errx(1, "unknown class: %s", class);
 371         }
 372
 373         /* if asme and non-standard target shell, must be root */
 374         if (asme) {
 375                 if (ruid != 0 && !chshell(pwd->pw_shell))
 376                         errx(1, "permission denied (shell)");
 377         }
 378         else if (pwd->pw_shell && *pwd->pw_shell) {
 379                 shell = pwd->pw_shell;
 380                 iscsh = UNSET;
 381         }
 382         else {
 383                 shell = _PATH_BSHELL;
 384                 iscsh = NO;
 385         }
 386
 387         /* if we're forking a csh, we want to slightly muck the args */
 388         if (iscsh == UNSET) {
 389                 p = strrchr(shell, '/');
 390                 if (p)
 391                         ++p;
 392                 else
 393                         p = shell;
 394                 iscsh = strcmp(p, "csh") ? (strcmp(p, "tcsh") ? NO : YES) : YES;
 395         }
 396         setpriority(PRIO_PROCESS, 0, prio);
 397
 398         /*
 399          * PAM modules might add supplementary groups in pam_setcred(), so
 400          * initialize them first.
 401          */
 402         if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) < 0)
 403                 err(1, "setusercontext");
 404
 405         retcode = pam_setcred(pamh, PAM_ESTABLISH_CRED);
 406         if (retcode != PAM_SUCCESS) {
 407                 syslog(LOG_ERR, "pam_setcred: %s",
 408                     pam_strerror(pamh, retcode));
 409                 errx(1, "failed to establish credentials.");
 410         }
 411         if (asthem) {
 412                 retcode = pam_open_session(pamh, 0);
 413                 if (retcode != PAM_SUCCESS) {
 414                         syslog(LOG_ERR, "pam_open_session: %s",
 415                             pam_strerror(pamh, retcode));
 416                         errx(1, "failed to open session.");
 417                 }
 418         }
 419
 420         /*
 421          * We must fork() before setuid() because we need to call
 422          * pam_setcred(pamh, PAM_DELETE_CRED) as root.
 423          */
 424         sa.sa_flags = SA_RESTART;
 425         sa.sa_handler = SIG_IGN;
 426         sigemptyset(&sa.sa_mask);
 427         sigaction(SIGINT, &sa, &sa_int);
 428         sigaction(SIGQUIT, &sa, &sa_quit);
 429         sigaction(SIGPIPE, &sa, &sa_pipe);
 430         sa.sa_handler = SIG_DFL;
 431         sigaction(SIGTSTP, &sa, NULL);
 432         statusp = 1;
 433         if (pipe(fds) == -1) {
 434                 PAM_END();
 435                 err(1, "pipe");
 436         }
 437         child_pid = fork();
 438         switch (child_pid) {
 439         default:
 440                 sa.sa_handler = SIG_IGN;
 441                 sigaction(SIGTTOU, &sa, NULL);
 442                 close(fds[0]);
 443                 setpgid(child_pid, child_pid);
 444                 if (tcgetpgrp(STDERR_FILENO) == getpgrp())
 445                         tcsetpgrp(STDERR_FILENO, child_pid);
 446                 close(fds[1]);
 447                 sigaction(SIGPIPE, &sa_pipe, NULL);
 448                 while ((pid = waitpid(child_pid, &statusp, WUNTRACED)) != -1) {
 449                         if (WIFSTOPPED(statusp)) {
 450                                 child_pgrp = getpgid(child_pid);
 451                                 if (tcgetpgrp(STDERR_FILENO) == child_pgrp)
 452                                         tcsetpgrp(STDERR_FILENO, getpgrp());
 453                                 kill(getpid(), SIGSTOP);
 454                                 if (tcgetpgrp(STDERR_FILENO) == getpgrp()) {
 455                                         child_pgrp = getpgid(child_pid);
 456                                         tcsetpgrp(STDERR_FILENO, child_pgrp);
 457                                 }
 458                                 kill(child_pid, SIGCONT);
 459                                 statusp = 1;
 460                                 continue;
 461                         }
 462                         break;
 463                 }
 464                 tcsetpgrp(STDERR_FILENO, getpgrp());
 465                 if (pid == -1)
 466                         err(1, "waitpid");
 467                 PAM_END();
 468                 exit(WEXITSTATUS(statusp));
 469         case -1:
 470                 PAM_END();
 471                 err(1, "fork");
 472         case 0:
 473                 close(fds[1]);
 474                 read(fds[0], &temp, 1);
 475                 close(fds[0]);
 476                 sigaction(SIGPIPE, &sa_pipe, NULL);
 477                 sigaction(SIGINT, &sa_int, NULL);
 478                 sigaction(SIGQUIT, &sa_quit, NULL);
 479
 480                 /*
 481                  * Set all user context except for: Environmental variables
 482                  * Umask Login records (wtmp, etc) Path
 483                  * XXX Missing LOGIN_SETMAC
 484                  */
 485                 setwhat = LOGIN_SETALL & ~(LOGIN_SETENV | LOGIN_SETUMASK |
 486                            LOGIN_SETLOGIN | LOGIN_SETPATH | LOGIN_SETGROUP);
 487 #if 0
 488                 /*
 489                  * If -s is present, also set the MAC label.
 490                  */
 491                 if (setmaclabel)
 492                         setwhat |= LOGIN_SETMAC;
 493 #endif
 494                 /*
 495                  * Don't touch resource/priority settings if -m has been used
 496                  * or -l and -c hasn't, and we're not su'ing to root.
 497                  */
 498                 if ((asme || (!asthem && class == NULL)) && pwd->pw_uid)
 499                         setwhat &= ~(LOGIN_SETPRIORITY | LOGIN_SETRESOURCES);
 500                 if (setusercontext(lc, pwd, pwd->pw_uid, setwhat) < 0)
 501                         err(1, "setusercontext");
 502
 503                 if (!asme) {
 504                         if (asthem) {
 505                                 p = getenv("TERM");
 506                                 environ = &cleanenv;
 507                         }
 508
 509                         if (asthem || pwd->pw_uid) {
 510                                 if (setenv("USER", pwd->pw_name, 1) == -1) {
 511                                         err(1, "setenv: cannot set USER=%s",
 512                                             pwd->pw_name);
 513                                 }
 514                         }
 515                         if (setenv("HOME", pwd->pw_dir, 1) == -1) {
 516                                 err(1, "setenv: cannot set HOME=%s",
 517                                     pwd->pw_dir);
 518                         }
 519                         if (setenv("SHELL", shell, 1) == -1)
 520                                 err(1, "setenv: cannot set SHELL=%s", shell);
 521
 522                         if (asthem) {
 523                                 /*
 524                                  * Add any environmental variables that the
 525                                  * PAM modules may have set.
 526                                  */
 527                                 environ_pam = pam_getenvlist(pamh);
 528                                 if (environ_pam)
 529                                         export_pam_environment();
 530
 531                                 /* set the su'd user's environment & umask */
 532                                 setusercontext(lc, pwd, pwd->pw_uid,
 533                                         LOGIN_SETPATH | LOGIN_SETUMASK |
 534                                         LOGIN_SETENV);
 535                                 if (p) {
 536                                         if (setenv("TERM", p, 1) == -1) {
 537                                                 err(1,
 538                                                     "setenv: cannot set TERM=%s",
 539                                                     p);
 540                                         }
 541                                 }
 542
 543                                 p = pam_getenv(pamh, "HOME");
 544                                 if (chdir(p ? p : pwd->pw_dir) < 0)
 545                                         errx(1, "no directory");
 546                         }
 547                 }
 548                 login_close(lc);
 549
 550                 if (iscsh == YES) {
 551                         if (fastlogin)
 552                                 *np.a-- = "-f";
 553                         if (asme)
 554                                 *np.a-- = "-m";
 555                 }
 556                 /* csh strips the first character... */
 557                 *np.a = asthem ? "-su" : iscsh == YES ? "_su" : "su";
 558
 559                 if (ruid != 0)
 560                         syslog(LOG_NOTICE, "%s to %s%s", username, user,
 561                             ontty());
 562
 563                 execv(shell, np.b);
 564                 err(1, "%s", shell);
 565         }
 566 }
 567
 568 static void
 569 export_pam_environment(void)
 570 {
 571         char    **pp;
 572         char    *p;
 573
 574         for (pp = environ_pam; *pp != NULL; pp++) {
 575                 if (ok_to_export(*pp)) {
 576                         p = strchr(*pp, '=');
 577                         *p = '\0';
 578                         if (setenv(*pp, p + 1, 1) == -1)
 579                                 err(1, "setenv: cannot set %s=%s", *pp, p + 1);
 580                 }
 581                 free(*pp);
 582         }
 583 }
 584
 585 /*
 586  * Sanity checks on PAM environmental variables:
 587  * - Make sure there is an '=' in the string.
 588  * - Make sure the string doesn't run on too long.
 589  * - Do not export certain variables.  This list was taken from the
 590  *   Solaris pam_putenv(3) man page.
 591  * Note that if the user is chrooted, PAM may have a better idea than we
 592  * do of where her home directory is.
 593  */
 594 static int
 595 ok_to_export(const char *s)
 596 {
 597         static const char *noexport[] = {
 598                 "SHELL", /* "HOME", */ "LOGNAME", "MAIL", "CDPATH",
 599                 "IFS", "PATH", NULL
 600         };
 601         const char **pp;
 602         size_t n;
 603
 604         if (strlen(s) > 1024 || strchr(s, '=') == NULL)
 605                 return 0;
 606         if (strncmp(s, "LD_", 3) == 0)
 607                 return 0;
 608         for (pp = noexport; *pp != NULL; pp++) {
 609                 n = strlen(*pp);
 610                 if (s[n] == '=' && strncmp(s, *pp, n) == 0)
 611                         return 0;
 612         }
 613         return 1;
 614 }
 615
 616 static void
 617 usage(void)
 618 {
 619
 620         fprintf(stderr, "usage: su [-] [-flm] [-c class] [login [args]]\n");
 621         exit(1);
 622         /* NOTREACHED */
 623 }
 624
 625 static int
 626 chshell(const char *sh)
 627 {
 628         int r;
 629         char *cp;
 630
 631         r = 0;
 632         setusershell();
 633         while ((cp = getusershell()) != NULL && !r)
 634             r = (strcmp(cp, sh) == 0);
 635         endusershell();
 636         return r;
 637 }
 638
 639 static char *
 640 ontty(void)
 641 {
 642         char *p;
 643         static char buf[MAXPATHLEN + 4];
 644
 645         buf[0] = 0;
 646         p = ttyname(STDERR_FILENO);
 647         if (p)
 648                 snprintf(buf, sizeof(buf), " on %s", p);
 649         return buf;
 650 }