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
  64 #ifndef lint
  65 static const char copyright[] =
  66 "@(#) Copyright (c) 1988, 1993, 1994\n\
  67         The Regents of the University of California.  All rights reserved.\n";
  68 #endif /* not lint */
  69
  70 #if 0
  71 #ifndef lint
  72 static char sccsid[] = "@(#)su.c        8.3 (Berkeley) 4/2/94";
  73 #endif /* not lint */
  74 #endif
  75
  76 #include <sys/cdefs.h>
  77 __FBSDID("$FreeBSD: src/usr.bin/su/su.c,v 1.91 2009/12/13 03:14:06 delphij Exp $");
  78
  79 #include <sys/param.h>
  80 #include <sys/time.h>
  81 #include <sys/resource.h>
  82 #include <sys/wait.h>
  83
  84 #ifdef USE_BSM_AUDIT
  85 #include <bsm/libbsm.h>
  86 #include <bsm/audit_uevents.h>
  87 #endif
  88
  89 #include <err.h>
  90 #include <errno.h>
  91 #include <grp.h>
  92 #ifndef __APPLE__
  93 #include <login_cap.h>
  94 #endif /* !__APPLE__ */
  95 #include <paths.h>
  96 #include <pwd.h>
  97 #include <signal.h>
  98 #include <stdio.h>
  99 #include <stdlib.h>
 100 #include <string.h>
 101 #include <syslog.h>
 102 #include <unistd.h>
 103 #include <stdarg.h>
 104
 105 #include <security/pam_appl.h>
 106 #include <security/openpam.h>
 107
 108 #ifdef __APPLE__
 109 #include <Security/AuthSession.h>
 110 #endif /* __APPLE__ */
 111
 112 #define PAM_END() do {                                                  \
 113         int local_ret;                                                  \
 114         if (pamh != NULL) {                                             \
 115                 local_ret = pam_setcred(pamh, PAM_DELETE_CRED);         \
 116                 if (local_ret != PAM_SUCCESS)                           \
 117                         syslog(LOG_ERR, "pam_setcred: %s",              \
 118                                 pam_strerror(pamh, local_ret));         \
 119                 if (asthem) {                                           \
 120                         local_ret = pam_close_session(pamh, 0);         \
 121                         if (local_ret != PAM_SUCCESS)                   \
 122                                 syslog(LOG_ERR, "pam_close_session: %s",\
 123                                         pam_strerror(pamh, local_ret)); \
 124                 }                                                       \
 125                 local_ret = pam_end(pamh, local_ret);                   \
 126                 if (local_ret != PAM_SUCCESS)                           \
 127                         syslog(LOG_ERR, "pam_end: %s",                  \
 128                                 pam_strerror(pamh, local_ret));         \
 129         }                                                               \
 130 } while (0)
 131
 132
 133 #define PAM_SET_ITEM(what, item) do {                                   \
 134         int local_ret;                                                  \
 135         local_ret = pam_set_item(pamh, what, item);                     \
 136         if (local_ret != PAM_SUCCESS) {                                 \
 137                 syslog(LOG_ERR, "pam_set_item(" #what "): %s",          \
 138                         pam_strerror(pamh, local_ret));                 \
 139                 errx(1, "pam_set_item(" #what "): %s",                  \
 140                         pam_strerror(pamh, local_ret));                 \
 141                 /* NOTREACHED */                                        \
 142         }                                                               \
 143 } while (0)
 144
 145 enum tristate { UNSET, YES, NO };
 146
 147 static pam_handle_t *pamh = NULL;
 148 static char     **environ_pam;
 149
 150 static char     *ontty(void);
 151 static int      chshell(const char *);
 152 static void     usage(void) __dead2;
 153 static void     export_pam_environment(void);
 154 static int      ok_to_export(const char *);
 155
 156 extern char     **environ;
 157
 158 int
 159 main(int argc, char *argv[])
 160 {
 161         static char     *cleanenv;
 162         struct passwd   *pwd;
 163         struct pam_conv conv = { openpam_ttyconv, NULL };
 164         enum tristate   iscsh;
 165 #ifndef __APPLE__
 166         login_cap_t     *lc;
 167 #endif /* !__APPLE__ */
 168         union {
 169                 const char      **a;
 170                 char            * const *b;
 171         }               np;
 172         uid_t           ruid;
 173         pid_t           child_pid, child_pgrp, pid;
 174         int             asme, ch, asthem, fastlogin, prio, i, retcode,
 175                         statusp, setmaclabel;
 176 #ifndef __APPLE__
 177         u_int           setwhat;
 178 #endif /* !__APPLE__ */
 179         char            *username, *class, shellbuf[MAXPATHLEN];
 180         const char      *p, *user, *shell, *mytty, **nargv;
 181         const void      *v;
 182         struct sigaction sa, sa_int, sa_quit, sa_pipe;
 183         int temp, fds[2];
 184 #ifdef USE_BSM_AUDIT
 185         const char      *aerr;
 186         au_id_t          auid;
 187 #endif
 188 #ifdef __APPLE__
 189         /* 4043304 */
 190         const char      *avshell;
 191         char            avshellbuf[MAXPATHLEN];
 192 #endif /* __APPLE__ */
 193
 194         shell = class = cleanenv = NULL;
 195         asme = asthem = fastlogin = statusp = 0;
 196         user = "root";
 197         iscsh = UNSET;
 198         setmaclabel = 0;
 199
 200 #ifdef __APPLE__
 201         while ((ch = getopt(argc, argv, "-flm")) != -1)
 202 #else
 203         while ((ch = getopt(argc, argv, "-flmsc:")) != -1)
 204 #endif /* __APPLE__ */
 205                 switch ((char)ch) {
 206                 case 'f':
 207                         fastlogin = 1;
 208                         break;
 209                 case '-':
 210                 case 'l':
 211                         asme = 0;
 212                         asthem = 1;
 213                         break;
 214                 case 'm':
 215                         asme = 1;
 216                         asthem = 0;
 217                         break;
 218 #ifndef __APPLE__
 219                 case 's':
 220                         setmaclabel = 1;
 221                         break;
 222                 case 'c':
 223                         class = optarg;
 224                         break;
 225 #endif /* !__APPLE__ */
 226                 case '?':
 227                 default:
 228                         usage();
 229                 /* NOTREACHED */
 230                 }
 231
 232         if (optind < argc)
 233                 user = argv[optind++];
 234
 235         if (user == NULL)
 236                 usage();
 237         /* NOTREACHED */
 238
 239         /*
 240          * Try to provide more helpful debugging output if su(1) is running
 241          * non-setuid, or was run from a file system not mounted setuid.
 242          */
 243         if (geteuid() != 0)
 244                 errx(1, "not running setuid");
 245
 246 #ifdef USE_BSM_AUDIT
 247         if (getauid(&auid) < 0 && errno != ENOSYS) {
 248                 syslog(LOG_AUTH | LOG_ERR, "getauid: %s", strerror(errno));
 249                 errx(1, "Permission denied");
 250         }
 251 #endif
 252         if (strlen(user) > MAXLOGNAME - 1) {
 253 #ifdef USE_BSM_AUDIT
 254                 if (audit_submit(AUE_su, auid,
 255                     EPERM, 1, "username too long: '%s'", user))
 256                         errx(1, "Permission denied");
 257 #endif
 258                 errx(1, "username too long");
 259         }
 260
 261         nargv = malloc(sizeof(char *) * (size_t)(argc + 4));
 262         if (nargv == NULL)
 263                 errx(1, "malloc failure");
 264
 265         nargv[argc + 3] = NULL;
 266         for (i = argc; i >= optind; i--)
 267                 nargv[i + 3] = argv[i];
 268         np.a = &nargv[i + 3];
 269
 270         argv += optind;
 271
 272         errno = 0;
 273         prio = getpriority(PRIO_PROCESS, 0);
 274         if (errno)
 275                 prio = 0;
 276
 277         setpriority(PRIO_PROCESS, 0, -2);
 278         openlog("su", LOG_CONS, LOG_AUTH);
 279
 280         /* get current login name, real uid and shell */
 281         ruid = getuid();
 282         username = getlogin();
 283         pwd = getpwnam(username);
 284         if (username == NULL || pwd == NULL || pwd->pw_uid != ruid)
 285                 pwd = getpwuid(ruid);
 286         if (pwd == NULL) {
 287 #ifdef USE_BSM_AUDIT
 288                 if (audit_submit(AUE_su, auid, EPERM, 1,
 289                     "unable to determine invoking subject: '%s'", username))
 290                         errx(1, "Permission denied");
 291 #endif
 292                 errx(1, "who are you?");
 293         }
 294
 295         username = strdup(pwd->pw_name);
 296         if (username == NULL)
 297                 err(1, "strdup failure");
 298
 299         if (asme) {
 300                 if (pwd->pw_shell != NULL && *pwd->pw_shell != '\0') {
 301                         /* must copy - pwd memory is recycled */
 302                         shell = strncpy(shellbuf, pwd->pw_shell,
 303                             sizeof(shellbuf));
 304                         shellbuf[sizeof(shellbuf) - 1] = '\0';
 305                 }
 306                 else {
 307                         shell = _PATH_BSHELL;
 308                         iscsh = NO;
 309                 }
 310         }
 311
 312         /* Do the whole PAM startup thing */
 313         retcode = pam_start("su", user, &conv, &pamh);
 314         if (retcode != PAM_SUCCESS) {
 315                 syslog(LOG_ERR, "pam_start: %s", pam_strerror(pamh, retcode));
 316                 errx(1, "pam_start: %s", pam_strerror(pamh, retcode));
 317         }
 318
 319         PAM_SET_ITEM(PAM_RUSER, username);
 320
 321         mytty = ttyname(STDERR_FILENO);
 322         if (!mytty)
 323                 mytty = "tty";
 324         PAM_SET_ITEM(PAM_TTY, mytty);
 325
 326         retcode = pam_authenticate(pamh, 0);
 327         if (retcode != PAM_SUCCESS) {
 328 #ifdef USE_BSM_AUDIT
 329                 if (audit_submit(AUE_su, auid, EPERM, 1, "bad su %s to %s on %s",
 330                     username, user, mytty))
 331                         errx(1, "Permission denied");
 332 #endif
 333                 syslog(LOG_AUTH|LOG_WARNING, "BAD SU %s to %s on %s",
 334                     username, user, mytty);
 335                 errx(1, "Sorry");
 336         }
 337 #ifdef USE_BSM_AUDIT
 338         if (audit_submit(AUE_su, auid, 0, 0, "successful authentication"))
 339                 errx(1, "Permission denied");
 340 #endif
 341         retcode = pam_get_item(pamh, PAM_USER, &v);
 342         if (retcode == PAM_SUCCESS)
 343                 user = v;
 344         else
 345                 syslog(LOG_ERR, "pam_get_item(PAM_USER): %s",
 346                     pam_strerror(pamh, retcode));
 347         pwd = getpwnam(user);
 348         if (pwd == NULL) {
 349 #ifdef USE_BSM_AUDIT
 350                 if (audit_submit(AUE_su, auid, EPERM, 1,
 351                     "unknown subject: %s", user))
 352                         errx(1, "Permission denied");
 353 #endif
 354                 errx(1, "unknown login: %s", user);
 355         }
 356
 357         retcode = pam_acct_mgmt(pamh, 0);
 358         if (retcode == PAM_NEW_AUTHTOK_REQD) {
 359                 retcode = pam_chauthtok(pamh,
 360                         PAM_CHANGE_EXPIRED_AUTHTOK);
 361                 if (retcode != PAM_SUCCESS) {
 362 #ifdef USE_BSM_AUDIT
 363                         aerr = pam_strerror(pamh, retcode);
 364                         if (aerr == NULL)
 365                                 aerr = "Unknown PAM error";
 366                         if (audit_submit(AUE_su, auid, EPERM, 1,
 367                             "pam_chauthtok: %s", aerr))
 368                                 errx(1, "Permission denied");
 369 #endif
 370                         syslog(LOG_ERR, "pam_chauthtok: %s",
 371                             pam_strerror(pamh, retcode));
 372                         errx(1, "Sorry");
 373                 }
 374         }
 375         if (retcode != PAM_SUCCESS) {
 376 #ifdef USE_BSM_AUDIT
 377                 if (audit_submit(AUE_su, auid, EPERM, 1, "pam_acct_mgmt: %s",
 378                     pam_strerror(pamh, retcode)))
 379                         errx(1, "Permission denied");
 380 #endif
 381                 syslog(LOG_ERR, "pam_acct_mgmt: %s",
 382                         pam_strerror(pamh, retcode));
 383                 errx(1, "Sorry");
 384         }
 385
 386 #ifndef __APPLE__
 387         /* get target login information */
 388         if (class == NULL)
 389                 lc = login_getpwclass(pwd);
 390         else {
 391                 if (ruid != 0) {
 392 #ifdef USE_BSM_AUDIT
 393                         if (audit_submit(AUE_su, auid, EPERM, 1,
 394                             "only root may use -c"))
 395                                 errx(1, "Permission denied");
 396 #endif
 397                         errx(1, "only root may use -c");
 398                 }
 399                 lc = login_getclass(class);
 400                 if (lc == NULL)
 401                         errx(1, "unknown class: %s", class);
 402         }
 403 #endif /* !__APPLE__ */
 404
 405         /* if asme and non-standard target shell, must be root */
 406         if (asme) {
 407                 if (ruid != 0 && !chshell(pwd->pw_shell))
 408                         errx(1, "permission denied (shell)");
 409         }
 410         else if (pwd->pw_shell && *pwd->pw_shell) {
 411 #ifdef __APPLE__
 412                 /* 3825554 */
 413                 shell = strncpy(shellbuf, pwd->pw_shell, sizeof(shellbuf));
 414                 shellbuf[sizeof(shellbuf) - 1] = '\0';
 415 #else
 416                 shell = pwd->pw_shell;
 417 #endif /* __APPLE__ */
 418                 iscsh = UNSET;
 419         }
 420         else {
 421                 shell = _PATH_BSHELL;
 422                 iscsh = NO;
 423         }
 424
 425         /* if we're forking a csh, we want to slightly muck the args */
 426         if (iscsh == UNSET) {
 427                 p = strrchr(shell, '/');
 428                 if (p)
 429                         ++p;
 430                 else
 431                         p = shell;
 432                 iscsh = strcmp(p, "csh") ? (strcmp(p, "tcsh") ? NO : YES) : YES;
 433         }
 434         setpriority(PRIO_PROCESS, 0, prio);
 435
 436         /*
 437          * PAM modules might add supplementary groups in pam_setcred(), so
 438          * initialize them first.
 439          */
 440 #ifdef __APPLE__
 441         if (initgroups(user, pwd->pw_gid))
 442                 err(1, "initgroups");
 443 #else
 444         if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) < 0)
 445                 err(1, "setusercontext");
 446 #endif /* __APPLE__ */
 447
 448 #ifdef __APPLE__
 449         /* 8530846 */
 450         if (asthem) {
 451                 retcode = SessionCreate(0, 0);
 452                 if (retcode != noErr) {
 453                         syslog(LOG_ERR, "SessionCreate: %d", retcode);
 454                         errx(1, "failed to create session.");
 455                 }
 456         }
 457 #endif /* __APPLE__ */
 458
 459         retcode = pam_setcred(pamh, PAM_ESTABLISH_CRED);
 460         if (retcode != PAM_SUCCESS) {
 461                 syslog(LOG_ERR, "pam_setcred: %s",
 462                     pam_strerror(pamh, retcode));
 463                 errx(1, "failed to establish credentials.");
 464         }
 465         if (asthem) {
 466                 retcode = pam_open_session(pamh, 0);
 467                 if (retcode != PAM_SUCCESS) {
 468                         syslog(LOG_ERR, "pam_open_session: %s",
 469                             pam_strerror(pamh, retcode));
 470                         errx(1, "failed to open session.");
 471                 }
 472         }
 473
 474         /*
 475          * We must fork() before setuid() because we need to call
 476          * pam_setcred(pamh, PAM_DELETE_CRED) as root.
 477          */
 478         sa.sa_flags = SA_RESTART;
 479         sa.sa_handler = SIG_IGN;
 480         sigemptyset(&sa.sa_mask);
 481         sigaction(SIGINT, &sa, &sa_int);
 482         sigaction(SIGQUIT, &sa, &sa_quit);
 483         sigaction(SIGPIPE, &sa, &sa_pipe);
 484         sa.sa_handler = SIG_DFL;
 485         sigaction(SIGTSTP, &sa, NULL);
 486         statusp = 1;
 487         if (pipe(fds) == -1) {
 488                 PAM_END();
 489                 err(1, "pipe");
 490         }
 491         child_pid = fork();
 492         switch (child_pid) {
 493         default:
 494                 sa.sa_handler = SIG_IGN;
 495                 sigaction(SIGTTOU, &sa, NULL);
 496                 close(fds[0]);
 497                 setpgid(child_pid, child_pid);
 498                 if (tcgetpgrp(STDERR_FILENO) == getpgrp())
 499                         tcsetpgrp(STDERR_FILENO, child_pid);
 500                 close(fds[1]);
 501                 sigaction(SIGPIPE, &sa_pipe, NULL);
 502                 while ((pid = waitpid(child_pid, &statusp, WUNTRACED)) != -1) {
 503                         if (WIFSTOPPED(statusp)) {
 504                                 child_pgrp = getpgid(child_pid);
 505                                 if (tcgetpgrp(STDERR_FILENO) == child_pgrp)
 506                                         tcsetpgrp(STDERR_FILENO, getpgrp());
 507                                 kill(getpid(), SIGSTOP);
 508                                 if (tcgetpgrp(STDERR_FILENO) == getpgrp()) {
 509                                         child_pgrp = getpgid(child_pid);
 510                                         tcsetpgrp(STDERR_FILENO, child_pgrp);
 511                                 }
 512                                 kill(child_pid, SIGCONT);
 513                                 statusp = 1;
 514                                 continue;
 515                         }
 516                         break;
 517                 }
 518                 tcsetpgrp(STDERR_FILENO, getpgrp());
 519                 if (pid == -1)
 520                         err(1, "waitpid");
 521                 PAM_END();
 522                 exit(WEXITSTATUS(statusp));
 523         case -1:
 524                 PAM_END();
 525                 err(1, "fork");
 526         case 0:
 527                 close(fds[1]);
 528                 read(fds[0], &temp, 1);
 529                 close(fds[0]);
 530                 sigaction(SIGPIPE, &sa_pipe, NULL);
 531                 sigaction(SIGINT, &sa_int, NULL);
 532                 sigaction(SIGQUIT, &sa_quit, NULL);
 533
 534 #ifdef __APPLE__
 535                 if (setgid(pwd->pw_gid))
 536                         err(1, "setgid");
 537                 /* Call initgroups(2) after setgid(2) to re-establish memberd */
 538                 if (initgroups(user, pwd->pw_gid))
 539                         err(1, "initgroups");
 540                 if (setuid(pwd->pw_uid))
 541                         err(1, "setuid");
 542 #else
 543                 /*
 544                  * Set all user context except for: Environmental variables
 545                  * Umask Login records (wtmp, etc) Path
 546                  */
 547                 setwhat = LOGIN_SETALL & ~(LOGIN_SETENV | LOGIN_SETUMASK |
 548                            LOGIN_SETLOGIN | LOGIN_SETPATH | LOGIN_SETGROUP |
 549                            LOGIN_SETMAC);
 550                 /*
 551                  * If -s is present, also set the MAC label.
 552                  */
 553                 if (setmaclabel)
 554                         setwhat |= LOGIN_SETMAC;
 555                 /*
 556                  * Don't touch resource/priority settings if -m has been used
 557                  * or -l and -c hasn't, and we're not su'ing to root.
 558                  */
 559                 if ((asme || (!asthem && class == NULL)) && pwd->pw_uid)
 560                         setwhat &= ~(LOGIN_SETPRIORITY | LOGIN_SETRESOURCES);
 561                 if (setusercontext(lc, pwd, pwd->pw_uid, setwhat) < 0)
 562                         err(1, "setusercontext");
 563 #endif /* __APPLE__ */
 564
 565                 if (!asme) {
 566                         if (asthem) {
 567                                 p = getenv("TERM");
 568                                 environ = &cleanenv;
 569                         }
 570
 571                         if (asthem || pwd->pw_uid)
 572                                 setenv("USER", pwd->pw_name, 1);
 573                         setenv("HOME", pwd->pw_dir, 1);
 574                         setenv("SHELL", shell, 1);
 575 #ifdef __APPLE__
 576                         unsetenv("TMPDIR");
 577 #endif /* __APPLE__ */
 578
 579                         if (asthem) {
 580                                 /*
 581                                  * Add any environmental variables that the
 582                                  * PAM modules may have set.
 583                                  */
 584                                 environ_pam = pam_getenvlist(pamh);
 585                                 if (environ_pam)
 586                                         export_pam_environment();
 587
 588 #ifdef __APPLE__
 589                                 /* 5276965: As documented, set $PATH. */
 590                                 setenv("PATH", "/bin:/usr/bin", 1);
 591 #else
 592                                 /* set the su'd user's environment & umask */
 593                                 setusercontext(lc, pwd, pwd->pw_uid,
 594                                         LOGIN_SETPATH | LOGIN_SETUMASK |
 595                                         LOGIN_SETENV);
 596 #endif /* __APPLE__ */
 597                                 if (p)
 598                                         setenv("TERM", p, 1);
 599
 600                                 p = pam_getenv(pamh, "HOME");
 601                                 if (chdir(p ? p : pwd->pw_dir) < 0)
 602                                         errx(1, "no directory");
 603                         }
 604                 }
 605 #ifndef __APPLE__
 606                 login_close(lc);
 607 #endif /* !__APPLE__ */
 608
 609                 if (iscsh == YES) {
 610                         if (fastlogin)
 611                                 *np.a-- = "-f";
 612                         if (asme)
 613                                 *np.a-- = "-m";
 614                 }
 615 #ifdef __APPLE__
 616                 /* 4043304 */
 617                 if ((p = strrchr(shell, '/')) != NULL)
 618                         avshell = p + 1;
 619                 else
 620                         avshell = shell;
 621
 622                 if (asthem) {
 623                         avshellbuf[0] = '-';
 624                         strlcpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 1);
 625                         avshell = avshellbuf;
 626                 }
 627
 628                 /* csh *no longer* strips the first character... */
 629                 *np.a = avshell;
 630 #else
 631                 /* csh strips the first character... */
 632                 *np.a = asthem ? "-su" : iscsh == YES ? "_su" : "su";
 633 #endif /* __APPLE__ */
 634
 635                 if (ruid != 0)
 636                         syslog(LOG_NOTICE, "%s to %s%s", username, user,
 637                             ontty());
 638
 639                 execv(shell, np.b);
 640                 err(1, "%s", shell);
 641         }
 642 }
 643
 644 static void
 645 export_pam_environment(void)
 646 {
 647         char    **pp;
 648         char    *p;
 649
 650         for (pp = environ_pam; *pp != NULL; pp++) {
 651                 if (ok_to_export(*pp)) {
 652                         p = strchr(*pp, '=');
 653                         *p = '\0';
 654                         setenv(*pp, p + 1, 1);
 655                 }
 656                 free(*pp);
 657         }
 658 }
 659
 660 /*
 661  * Sanity checks on PAM environmental variables:
 662  * - Make sure there is an '=' in the string.
 663  * - Make sure the string doesn't run on too long.
 664  * - Do not export certain variables.  This list was taken from the
 665  *   Solaris pam_putenv(3) man page.
 666  * Note that if the user is chrooted, PAM may have a better idea than we
 667  * do of where her home directory is.
 668  */
 669 static int
 670 ok_to_export(const char *s)
 671 {
 672         static const char *noexport[] = {
 673                 "SHELL", /* "HOME", */ "LOGNAME", "MAIL", "CDPATH",
 674                 "IFS", "PATH", NULL
 675         };
 676         const char **pp;
 677         size_t n;
 678
 679         if (strlen(s) > 1024 || strchr(s, '=') == NULL)
 680                 return 0;
 681         if (strncmp(s, "LD_", 3) == 0)
 682                 return 0;
 683         for (pp = noexport; *pp != NULL; pp++) {
 684                 n = strlen(*pp);
 685                 if (s[n] == '=' && strncmp(s, *pp, n) == 0)
 686                         return 0;
 687         }
 688         return 1;
 689 }
 690
 691 static void
 692 usage(void)
 693 {
 694
 695 #ifdef __APPLE__
 696         fprintf(stderr, "usage: su [-] [-flm] [login [args]]\n");
 697 #else
 698         fprintf(stderr, "usage: su [-] [-flms] [-c class] [login [args]]\n");
 699 #endif /* __APPLE__ */
 700         exit(1);
 701         /* NOTREACHED */
 702 }
 703
 704 static int
 705 chshell(const char *sh)
 706 {
 707         int r;
 708         char *cp;
 709
 710         r = 0;
 711         setusershell();
 712         while ((cp = getusershell()) != NULL && !r)
 713             r = (strcmp(cp, sh) == 0);
 714         endusershell();
 715         return r;
 716 }
 717
 718 static char *
 719 ontty(void)
 720 {
 721         char *p;
 722         static char buf[MAXPATHLEN + 4];
 723
 724         buf[0] = 0;
 725         p = ttyname(STDERR_FILENO);
 726         if (p)
 727                 snprintf(buf, sizeof(buf), " on %s", p);
 728         return buf;
 729 }