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 1.87 2007/10/18 11:05:30 davidxu 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 #define PAM_END() do {                                                  \
 109         int local_ret;                                                  \
 110         if (pamh != NULL) {                                             \
 111                 local_ret = pam_setcred(pamh, PAM_DELETE_CRED);         \
 112                 if (local_ret != PAM_SUCCESS)                           \
 113                         syslog(LOG_ERR, "pam_setcred: %s",              \
 114                                 pam_strerror(pamh, local_ret));         \
 115                 if (asthem) {                                           \
 116                         local_ret = pam_close_session(pamh, 0);         \
 117                         if (local_ret != PAM_SUCCESS)                   \
 118                                 syslog(LOG_ERR, "pam_close_session: %s",\
 119                                         pam_strerror(pamh, local_ret)); \
 120                 }                                                       \
 121                 local_ret = pam_end(pamh, local_ret);                   \
 122                 if (local_ret != PAM_SUCCESS)                           \
 123                         syslog(LOG_ERR, "pam_end: %s",                  \
 124                                 pam_strerror(pamh, local_ret));         \
 125         }                                                               \
 126 } while (0)
 127
 128
 129 #define PAM_SET_ITEM(what, item) do {                                   \
 130         int local_ret;                                                  \
 131         local_ret = pam_set_item(pamh, what, item);                     \
 132         if (local_ret != PAM_SUCCESS) {                                 \
 133                 syslog(LOG_ERR, "pam_set_item(" #what "): %s",          \
 134                         pam_strerror(pamh, local_ret));                 \
 135                 errx(1, "pam_set_item(" #what "): %s",                  \
 136                         pam_strerror(pamh, local_ret));                 \
 137                 /* NOTREACHED */                                        \
 138         }                                                               \
 139 } while (0)
 140
 141 enum tristate { UNSET, YES, NO };
 142
 143 static pam_handle_t *pamh = NULL;
 144 static char     **environ_pam;
 145
 146 static char     *ontty(void);
 147 static int      chshell(const char *);
 148 static void     usage(void) __dead2;
 149 static void     export_pam_environment(void);
 150 static int      ok_to_export(const char *);
 151
 152 extern char     **environ;
 153
 154 int
 155 main(int argc, char *argv[])
 156 {
 157         static char     *cleanenv;
 158         struct passwd   *pwd;
 159         struct pam_conv conv = { openpam_ttyconv, NULL };
 160         enum tristate   iscsh;
 161 #ifndef __APPLE__
 162         login_cap_t     *lc;
 163 #endif /* !__APPLE__ */
 164         union {
 165                 const char      **a;
 166                 char            * const *b;
 167         }               np;
 168         uid_t           ruid;
 169         pid_t           child_pid, child_pgrp, pid;
 170         int             asme, ch, asthem, fastlogin, prio, i, retcode,
 171                         statusp, setmaclabel;
 172 #ifndef __APPLE__
 173         u_int           setwhat;
 174 #endif /* !__APPLE__ */
 175         char            *username, *class, shellbuf[MAXPATHLEN];
 176         const char      *p, *user, *shell, *mytty, **nargv;
 177         struct sigaction sa, sa_int, sa_quit, sa_pipe;
 178         int temp, fds[2];
 179 #ifdef USE_BSM_AUDIT
 180         const char      *aerr;
 181         au_id_t          auid;
 182 #endif
 183 #ifdef __APPLE__
 184         /* 4043304 */
 185         const char      *avshell;
 186         char            avshellbuf[MAXPATHLEN];
 187 #endif /* __APPLE__ */
 188
 189         shell = class = cleanenv = NULL;
 190         asme = asthem = fastlogin = statusp = 0;
 191         user = "root";
 192         iscsh = UNSET;
 193         setmaclabel = 0;
 194
 195 #ifdef __APPLE__
 196         while ((ch = getopt(argc, argv, "-flm")) != -1)
 197 #else
 198         while ((ch = getopt(argc, argv, "-flmsc:")) != -1)
 199 #endif /* __APPLE__ */
 200                 switch ((char)ch) {
 201                 case 'f':
 202                         fastlogin = 1;
 203                         break;
 204                 case '-':
 205                 case 'l':
 206                         asme = 0;
 207                         asthem = 1;
 208                         break;
 209                 case 'm':
 210                         asme = 1;
 211                         asthem = 0;
 212                         break;
 213 #ifndef __APPLE__
 214                 case 's':
 215                         setmaclabel = 1;
 216                         break;
 217                 case 'c':
 218                         class = optarg;
 219                         break;
 220 #endif /* !__APPLE__ */
 221                 case '?':
 222                 default:
 223                         usage();
 224                 /* NOTREACHED */
 225                 }
 226
 227         if (optind < argc)
 228                 user = argv[optind++];
 229
 230         if (user == NULL)
 231                 usage();
 232         /* NOTREACHED */
 233
 234         /*
 235          * Try to provide more helpful debugging output if su(1) is running
 236          * non-setuid, or was run from a file system not mounted setuid.
 237          */
 238         if (geteuid() != 0)
 239                 errx(1, "not running setuid");
 240
 241 #ifdef USE_BSM_AUDIT
 242         if (getauid(&auid) < 0 && errno != ENOSYS) {
 243                 syslog(LOG_AUTH | LOG_ERR, "getauid: %s", strerror(errno));
 244                 errx(1, "Permission denied");
 245         }
 246 #endif
 247         if (strlen(user) > MAXLOGNAME - 1) {
 248 #ifdef USE_BSM_AUDIT
 249                 if (audit_submit(AUE_su, auid,
 250                     1, EPERM, "username too long: '%s'", user))
 251                         errx(1, "Permission denied");
 252 #endif
 253                 errx(1, "username too long");
 254         }
 255
 256         nargv = malloc(sizeof(char *) * (size_t)(argc + 4));
 257         if (nargv == NULL)
 258                 errx(1, "malloc failure");
 259
 260         nargv[argc + 3] = NULL;
 261         for (i = argc; i >= optind; i--)
 262                 nargv[i + 3] = argv[i];
 263         np.a = &nargv[i + 3];
 264
 265         argv += optind;
 266
 267         errno = 0;
 268         prio = getpriority(PRIO_PROCESS, 0);
 269         if (errno)
 270                 prio = 0;
 271
 272         setpriority(PRIO_PROCESS, 0, -2);
 273         openlog("su", LOG_CONS, LOG_AUTH);
 274
 275         /* get current login name, real uid and shell */
 276         ruid = getuid();
 277         username = getlogin();
 278         pwd = getpwnam(username);
 279         if (username == NULL || pwd == NULL || pwd->pw_uid != ruid)
 280                 pwd = getpwuid(ruid);
 281         if (pwd == NULL) {
 282 #ifdef USE_BSM_AUDIT
 283                 if (audit_submit(AUE_su, auid, 1, EPERM,
 284                     "unable to determine invoking subject: '%s'", username))
 285                         errx(1, "Permission denied");
 286 #endif
 287                 errx(1, "who are you?");
 288         }
 289
 290         username = strdup(pwd->pw_name);
 291         if (username == NULL)
 292                 err(1, "strdup failure");
 293
 294         if (asme) {
 295                 if (pwd->pw_shell != NULL && *pwd->pw_shell != '\0') {
 296                         /* must copy - pwd memory is recycled */
 297                         shell = strncpy(shellbuf, pwd->pw_shell,
 298                             sizeof(shellbuf));
 299                         shellbuf[sizeof(shellbuf) - 1] = '\0';
 300                 }
 301                 else {
 302                         shell = _PATH_BSHELL;
 303                         iscsh = NO;
 304                 }
 305         }
 306
 307         /* Do the whole PAM startup thing */
 308         retcode = pam_start("su", user, &conv, &pamh);
 309         if (retcode != PAM_SUCCESS) {
 310                 syslog(LOG_ERR, "pam_start: %s", pam_strerror(pamh, retcode));
 311                 errx(1, "pam_start: %s", pam_strerror(pamh, retcode));
 312         }
 313
 314         PAM_SET_ITEM(PAM_RUSER, username);
 315
 316         mytty = ttyname(STDERR_FILENO);
 317         if (!mytty)
 318                 mytty = "tty";
 319         PAM_SET_ITEM(PAM_TTY, mytty);
 320
 321         retcode = pam_authenticate(pamh, 0);
 322         if (retcode != PAM_SUCCESS) {
 323 #ifdef USE_BSM_AUDIT
 324                 if (audit_submit(AUE_su, auid, 1, EPERM, "bad su %s to %s on %s",
 325                     username, user, mytty))
 326                         errx(1, "Permission denied");
 327 #endif
 328                 syslog(LOG_AUTH|LOG_WARNING, "BAD SU %s to %s on %s",
 329                     username, user, mytty);
 330                 errx(1, "Sorry");
 331         }
 332 #ifdef USE_BSM_AUDIT
 333         if (audit_submit(AUE_su, auid, 0, 0, "successful authentication"))
 334                 errx(1, "Permission denied");
 335 #endif
 336         retcode = pam_get_item(pamh, PAM_USER, (const void **)&p);
 337         if (retcode == PAM_SUCCESS)
 338                 user = p;
 339         else
 340                 syslog(LOG_ERR, "pam_get_item(PAM_USER): %s",
 341                     pam_strerror(pamh, retcode));
 342         pwd = getpwnam(user);
 343         if (pwd == NULL) {
 344 #ifdef USE_BSM_AUDIT
 345                 if (audit_submit(AUE_su, auid, 1, EPERM,
 346                     "unknown subject: %s", user))
 347                         errx(1, "Permission denied");
 348 #endif
 349                 errx(1, "unknown login: %s", user);
 350         }
 351
 352         retcode = pam_acct_mgmt(pamh, 0);
 353         if (retcode == PAM_NEW_AUTHTOK_REQD) {
 354                 retcode = pam_chauthtok(pamh,
 355                         PAM_CHANGE_EXPIRED_AUTHTOK);
 356                 if (retcode != PAM_SUCCESS) {
 357 #ifdef USE_BSM_AUDIT
 358                         aerr = pam_strerror(pamh, retcode);
 359                         if (aerr == NULL)
 360                                 aerr = "Unknown PAM error";
 361                         if (audit_submit(AUE_su, auid, 1, EPERM,
 362                             "pam_chauthtok: %s", aerr))
 363                                 errx(1, "Permission denied");
 364 #endif
 365                         syslog(LOG_ERR, "pam_chauthtok: %s",
 366                             pam_strerror(pamh, retcode));
 367                         errx(1, "Sorry");
 368                 }
 369         }
 370         if (retcode != PAM_SUCCESS) {
 371 #ifdef USE_BSM_AUDIT
 372                 if (audit_submit(AUE_su, auid, 1, EPERM, "pam_acct_mgmt: %s",
 373                     pam_strerror(pamh, retcode)))
 374                         errx(1, "Permission denied");
 375 #endif
 376                 syslog(LOG_ERR, "pam_acct_mgmt: %s",
 377                         pam_strerror(pamh, retcode));
 378                 errx(1, "Sorry");
 379         }
 380
 381 #ifndef __APPLE__
 382         /* get target login information */
 383         if (class == NULL)
 384                 lc = login_getpwclass(pwd);
 385         else {
 386                 if (ruid != 0) {
 387 #ifdef USE_BSM_AUDIT
 388                         if (audit_submit(AUE_su, auid, 1, EPERM,
 389                             "only root may use -c"))
 390                                 errx(1, "Permission denied");
 391 #endif
 392                         errx(1, "only root may use -c");
 393                 }
 394                 lc = login_getclass(class);
 395                 if (lc == NULL)
 396                         errx(1, "unknown class: %s", class);
 397         }
 398 #endif /* !__APPLE__ */
 399
 400         /* if asme and non-standard target shell, must be root */
 401         if (asme) {
 402                 if (ruid != 0 && !chshell(pwd->pw_shell))
 403                         errx(1, "permission denied (shell)");
 404         }
 405         else if (pwd->pw_shell && *pwd->pw_shell) {
 406 #ifdef __APPLE__
 407                 /* 3825554 */
 408                 shell = strncpy(shellbuf, pwd->pw_shell, sizeof(shellbuf));
 409                 shellbuf[sizeof(shellbuf) - 1] = '\0';
 410 #else
 411                 shell = pwd->pw_shell;
 412 #endif /* __APPLE__ */
 413                 iscsh = UNSET;
 414         }
 415         else {
 416                 shell = _PATH_BSHELL;
 417                 iscsh = NO;
 418         }
 419
 420         /* if we're forking a csh, we want to slightly muck the args */
 421         if (iscsh == UNSET) {
 422                 p = strrchr(shell, '/');
 423                 if (p)
 424                         ++p;
 425                 else
 426                         p = shell;
 427                 iscsh = strcmp(p, "csh") ? (strcmp(p, "tcsh") ? NO : YES) : YES;
 428         }
 429         setpriority(PRIO_PROCESS, 0, prio);
 430
 431         /*
 432          * PAM modules might add supplementary groups in pam_setcred(), so
 433          * initialize them first.
 434          */
 435 #ifdef __APPLE__
 436         if (initgroups(user, pwd->pw_gid))
 437                 err(1, "initgroups");
 438 #else
 439         if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) < 0)
 440                 err(1, "setusercontext");
 441 #endif /* __APPLE__ */
 442
 443         retcode = pam_setcred(pamh, PAM_ESTABLISH_CRED);
 444         if (retcode != PAM_SUCCESS) {
 445                 syslog(LOG_ERR, "pam_setcred: %s",
 446                     pam_strerror(pamh, retcode));
 447                 errx(1, "failed to establish credentials.");
 448         }
 449         if (asthem) {
 450                 retcode = pam_open_session(pamh, 0);
 451                 if (retcode != PAM_SUCCESS) {
 452                         syslog(LOG_ERR, "pam_open_session: %s",
 453                             pam_strerror(pamh, retcode));
 454                         errx(1, "failed to open session.");
 455                 }
 456         }
 457
 458         /*
 459          * We must fork() before setuid() because we need to call
 460          * pam_setcred(pamh, PAM_DELETE_CRED) as root.
 461          */
 462         sa.sa_flags = SA_RESTART;
 463         sa.sa_handler = SIG_IGN;
 464         sigemptyset(&sa.sa_mask);
 465         sigaction(SIGINT, &sa, &sa_int);
 466         sigaction(SIGQUIT, &sa, &sa_quit);
 467         sigaction(SIGPIPE, &sa, &sa_pipe);
 468         sa.sa_handler = SIG_DFL;
 469         sigaction(SIGTSTP, &sa, NULL);
 470         statusp = 1;
 471         if (pipe(fds) == -1) {
 472                 PAM_END();
 473                 err(1, "pipe");
 474         }
 475         child_pid = fork();
 476         switch (child_pid) {
 477         default:
 478                 sa.sa_handler = SIG_IGN;
 479                 sigaction(SIGTTOU, &sa, NULL);
 480                 close(fds[0]);
 481                 setpgid(child_pid, child_pid);
 482                 if (tcgetpgrp(STDERR_FILENO) == getpgrp())
 483                         tcsetpgrp(STDERR_FILENO, child_pid);
 484                 close(fds[1]);
 485                 sigaction(SIGPIPE, &sa_pipe, NULL);
 486                 while ((pid = waitpid(child_pid, &statusp, WUNTRACED)) != -1) {
 487                         if (WIFSTOPPED(statusp)) {
 488                                 child_pgrp = getpgid(child_pid);
 489                                 if (tcgetpgrp(STDERR_FILENO) == child_pgrp)
 490                                         tcsetpgrp(STDERR_FILENO, getpgrp());
 491                                 kill(getpid(), SIGSTOP);
 492                                 if (tcgetpgrp(STDERR_FILENO) == getpgrp()) {
 493                                         child_pgrp = getpgid(child_pid);
 494                                         tcsetpgrp(STDERR_FILENO, child_pgrp);
 495                                 }
 496                                 kill(child_pid, SIGCONT);
 497                                 statusp = 1;
 498                                 continue;
 499                         }
 500                         break;
 501                 }
 502                 tcsetpgrp(STDERR_FILENO, getpgrp());
 503                 if (pid == -1)
 504                         err(1, "waitpid");
 505                 PAM_END();
 506                 exit(WEXITSTATUS(statusp));
 507         case -1:
 508                 PAM_END();
 509                 err(1, "fork");
 510         case 0:
 511                 close(fds[1]);
 512                 read(fds[0], &temp, 1);
 513                 close(fds[0]);
 514                 sigaction(SIGPIPE, &sa_pipe, NULL);
 515                 sigaction(SIGINT, &sa_int, NULL);
 516                 sigaction(SIGQUIT, &sa_quit, NULL);
 517
 518 #ifdef __APPLE__
 519                 if (setgid(pwd->pw_gid))
 520                         err(1, "setgid");
 521                 /* Call initgroups(2) after setgid(2) to re-establish memberd */
 522                 if (initgroups(user, pwd->pw_gid))
 523                         err(1, "initgroups");
 524                 if (setuid(pwd->pw_uid))
 525                         err(1, "setuid");
 526 #else
 527                 /*
 528                  * Set all user context except for: Environmental variables
 529                  * Umask Login records (wtmp, etc) Path
 530                  */
 531                 setwhat = LOGIN_SETALL & ~(LOGIN_SETENV | LOGIN_SETUMASK |
 532                            LOGIN_SETLOGIN | LOGIN_SETPATH | LOGIN_SETGROUP |
 533                            LOGIN_SETMAC);
 534                 /*
 535                  * If -s is present, also set the MAC label.
 536                  */
 537                 if (setmaclabel)
 538                         setwhat |= LOGIN_SETMAC;
 539                 /*
 540                  * Don't touch resource/priority settings if -m has been used
 541                  * or -l and -c hasn't, and we're not su'ing to root.
 542                  */
 543                 if ((asme || (!asthem && class == NULL)) && pwd->pw_uid)
 544                         setwhat &= ~(LOGIN_SETPRIORITY | LOGIN_SETRESOURCES);
 545                 if (setusercontext(lc, pwd, pwd->pw_uid, setwhat) < 0)
 546                         err(1, "setusercontext");
 547 #endif /* __APPLE__ */
 548
 549                 if (!asme) {
 550                         if (asthem) {
 551                                 p = getenv("TERM");
 552                                 environ = &cleanenv;
 553                         }
 554
 555                         if (asthem || pwd->pw_uid)
 556                                 setenv("USER", pwd->pw_name, 1);
 557                         setenv("HOME", pwd->pw_dir, 1);
 558                         setenv("SHELL", shell, 1);
 559 #ifdef __APPLE__
 560                         unsetenv("TMPDIR");
 561 #endif /* __APPLE__ */
 562
 563                         if (asthem) {
 564                                 /*
 565                                  * Add any environmental variables that the
 566                                  * PAM modules may have set.
 567                                  */
 568                                 environ_pam = pam_getenvlist(pamh);
 569                                 if (environ_pam)
 570                                         export_pam_environment();
 571
 572 #ifdef __APPLE__
 573                                 /* 5276965: As documented, set $PATH. */
 574                                 setenv("PATH", "/bin:/usr/bin", 1);
 575 #else
 576                                 /* set the su'd user's environment & umask */
 577                                 setusercontext(lc, pwd, pwd->pw_uid,
 578                                         LOGIN_SETPATH | LOGIN_SETUMASK |
 579                                         LOGIN_SETENV);
 580 #endif /* __APPLE__ */
 581                                 if (p)
 582                                         setenv("TERM", p, 1);
 583
 584                                 p = pam_getenv(pamh, "HOME");
 585                                 if (chdir(p ? p : pwd->pw_dir) < 0)
 586                                         errx(1, "no directory");
 587                         }
 588                 }
 589 #ifndef __APPLE__
 590                 login_close(lc);
 591 #endif /* !__APPLE__ */
 592
 593                 if (iscsh == YES) {
 594                         if (fastlogin)
 595                                 *np.a-- = "-f";
 596                         if (asme)
 597                                 *np.a-- = "-m";
 598                 }
 599 #ifdef __APPLE__
 600                 /* 4043304 */
 601                 if ((p = strrchr(shell, '/')) != NULL)
 602                         avshell = p + 1;
 603                 else
 604                         avshell = shell;
 605
 606                 if (asthem) {
 607                         avshellbuf[0] = '-';
 608                         strlcpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 1);
 609                         avshell = avshellbuf;
 610                 }
 611
 612                 /* csh *no longer* strips the first character... */
 613                 *np.a = avshell;
 614 #else
 615                 /* csh strips the first character... */
 616                 *np.a = asthem ? "-su" : iscsh == YES ? "_su" : "su";
 617 #endif /* __APPLE__ */
 618
 619                 if (ruid != 0)
 620                         syslog(LOG_NOTICE, "%s to %s%s", username, user,
 621                             ontty());
 622
 623                 execv(shell, np.b);
 624                 err(1, "%s", shell);
 625         }
 626 }
 627
 628 static void
 629 export_pam_environment(void)
 630 {
 631         char    **pp;
 632         char    *p;
 633
 634         for (pp = environ_pam; *pp != NULL; pp++) {
 635                 if (ok_to_export(*pp)) {
 636                         p = strchr(*pp, '=');
 637                         *p = '\0';
 638                         setenv(*pp, p + 1, 1);
 639                 }
 640                 free(*pp);
 641         }
 642 }
 643
 644 /*
 645  * Sanity checks on PAM environmental variables:
 646  * - Make sure there is an '=' in the string.
 647  * - Make sure the string doesn't run on too long.
 648  * - Do not export certain variables.  This list was taken from the
 649  *   Solaris pam_putenv(3) man page.
 650  * Note that if the user is chrooted, PAM may have a better idea than we
 651  * do of where her home directory is.
 652  */
 653 static int
 654 ok_to_export(const char *s)
 655 {
 656         static const char *noexport[] = {
 657                 "SHELL", /* "HOME", */ "LOGNAME", "MAIL", "CDPATH",
 658                 "IFS", "PATH", NULL
 659         };
 660         const char **pp;
 661         size_t n;
 662
 663         if (strlen(s) > 1024 || strchr(s, '=') == NULL)
 664                 return 0;
 665         if (strncmp(s, "LD_", 3) == 0)
 666                 return 0;
 667         for (pp = noexport; *pp != NULL; pp++) {
 668                 n = strlen(*pp);
 669                 if (s[n] == '=' && strncmp(s, *pp, n) == 0)
 670                         return 0;
 671         }
 672         return 1;
 673 }
 674
 675 static void
 676 usage(void)
 677 {
 678
 679 #ifdef __APPLE__
 680         fprintf(stderr, "usage: su [-] [-flm] [login [args]]\n");
 681 #else
 682         fprintf(stderr, "usage: su [-] [-flms] [-c class] [login [args]]\n");
 683 #endif /* __APPLE__ */
 684         exit(1);
 685         /* NOTREACHED */
 686 }
 687
 688 static int
 689 chshell(const char *sh)
 690 {
 691         int r;
 692         char *cp;
 693
 694         r = 0;
 695         setusershell();
 696         while ((cp = getusershell()) != NULL && !r)
 697             r = (strcmp(cp, sh) == 0);
 698         endusershell();
 699         return r;
 700 }
 701
 702 static char *
 703 ontty(void)
 704 {
 705         char *p;
 706         static char buf[MAXPATHLEN + 4];
 707
 708         buf[0] = 0;
 709         p = ttyname(STDERR_FILENO);
 710         if (p)
 711                 snprintf(buf, sizeof(buf), " on %s", p);
 712         return buf;
 713 }