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