2007-10-07 17:14:02 +05:30
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/*
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* Copyright 1990 - 1994, Julianne Frances Haugh
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of Julianne F. Haugh nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY JULIE HAUGH AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL JULIE HAUGH OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <config.h>
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#include "rcsid.h"
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2007-10-07 17:14:51 +05:30
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RCSID(PKG_VER "$Id: newgrp.c,v 1.17 2001/09/01 04:19:16 kloczek Exp $")
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2007-10-07 17:14:02 +05:30
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#include <stdio.h>
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#include <errno.h>
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#include <grp.h>
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#include <pwd.h>
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#include "prototypes.h"
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#include "defines.h"
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#include "getdef.h"
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extern char **environ;
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#ifdef HAVE_SETGROUPS
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static int ngroups;
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static GETGROUPS_T *grouplist;
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#endif
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static char *Prog;
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static int is_newgrp;
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/* local function prototypes */
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2007-10-07 17:14:14 +05:30
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static void usage(void);
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2007-10-07 17:14:02 +05:30
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/*
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* usage - print command usage message
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*/
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static void
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usage(void)
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{
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if (is_newgrp)
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fprintf (stderr, _("usage: newgrp [ - ] [ group ]\n"));
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else
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2007-10-07 17:14:08 +05:30
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fprintf (stderr, _("usage: sg group [[-c] command ]\n"));
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2007-10-07 17:14:02 +05:30
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}
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/*
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* newgrp - change the invokers current real and effective group id
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*/
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int
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main(int argc, char **argv)
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{
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int initflag = 0;
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int needspasswd = 0;
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int i;
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2007-10-07 17:14:14 +05:30
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int their_grp = 0;
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2007-10-07 17:14:02 +05:30
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int cflag = 0;
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gid_t gid;
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char *cp;
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const char *cpasswd, *name, *prog;
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char *group = NULL;
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char *command=NULL;
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char **envp = environ;
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struct passwd *pwd;
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struct group *grp;
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#ifdef SHADOWPWD
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struct spwd *spwd;
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#endif
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#ifdef SHADOWGRP
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struct sgrp *sgrp;
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#endif
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2007-10-07 17:14:14 +05:30
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#if ENABLE_NLS
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/* XXX - remove when gettext is safe to use in setuid programs */
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2007-10-07 17:14:02 +05:30
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sanitize_env();
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2007-10-07 17:14:14 +05:30
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#endif
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2007-10-07 17:14:02 +05:30
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setlocale(LC_ALL, "");
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bindtextdomain(PACKAGE, LOCALEDIR);
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textdomain(PACKAGE);
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/*
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* save my name for error messages and save my real gid incase
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* of errors. if there is an error i have to exec a new login
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* shell for the user since her old shell won't have fork'd to
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* create the process. skip over the program name to the next
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* command line argument.
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*/
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Prog = Basename(argv[0]);
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is_newgrp = (strcmp(Prog, "newgrp") == 0);
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2007-10-07 17:14:32 +05:30
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OPENLOG(is_newgrp ? "newgrp" : "sg");
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2007-10-07 17:14:02 +05:30
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gid = getgid();
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argc--; argv++;
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initenv();
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pwd = get_my_pwent();
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if (!pwd) {
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fprintf (stderr, _("unknown uid: %d\n"), (int) getuid());
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SYSLOG((LOG_WARN, "unknown uid %d\n", (int) getuid()));
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closelog();
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exit(1);
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}
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name = pwd->pw_name;
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/*
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* Parse the command line. There are two accepted flags. The
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* first is "-", which for newgrp means to re-create the entire
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* environment as though a login had been performed, and "-c",
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* which for sg causes a command string to be executed.
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*
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* The next argument, if present, must be the new group name.
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* Any remaining remaining arguments will be used to execute a
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* command as the named group. If the group name isn't present,
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* I just use the login group ID of the current user.
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*
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* The valid syntax are
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* newgrp [ - ] [ groupid ]
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* newgrp [ -l ] [ groupid ]
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* sg [ - ]
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* sg [ - ] groupid [ command ]
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*/
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if (argc > 0 && (!strcmp(argv[0], "-") || !strcmp(argv[0], "-l"))) {
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argc--; argv++;
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initflag = 1;
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}
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if (!is_newgrp) {
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/*
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* Do the command line for everything that is
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* not "newgrp".
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*/
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if (argc > 0 && argv[0][0] != '-') {
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group = argv[0];
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argc--; argv++;
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} else {
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usage ();
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closelog();
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exit (1);
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}
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if (argc > 0) {
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2007-10-07 17:14:08 +05:30
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/* skip -c if specified so both forms work:
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"sg group -c command" (as in the man page) or
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"sg group command" (as in the usage message). */
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if (argc > 1 && strcmp(argv[0], "-c") == 0)
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command = argv[1];
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else
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command = argv[0];
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2007-10-07 17:14:02 +05:30
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cflag++;
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}
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} else {
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/*
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* Do the command line for "newgrp". It's just
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* making sure there aren't any flags and getting
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* the new group name.
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*/
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if (argc > 0 && argv[0][0] == '-') {
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usage ();
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goto failure;
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} else if (argv[0] != (char *) 0) {
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group = argv[0];
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} else {
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/*
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* get the group file entry for her login group id.
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* the entry must exist, simply to be annoying.
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*/
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if (! (grp = getgrgid (pwd->pw_gid))) {
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fprintf(stderr, _("unknown gid: %ld\n"),
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(long) pwd->pw_gid);
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SYSLOG((LOG_CRIT, "unknown gid: %ld\n",
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(long) pwd->pw_gid));
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goto failure;
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}
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}
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}
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#ifdef HAVE_SETGROUPS
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/*
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* get the current users groupset. the new group will be
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* added to the concurrent groupset if there is room, otherwise
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* you get a nasty message but at least your real and effective
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* group id's are set.
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*/
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/* don't use getgroups(0, 0) - it doesn't work on some systems */
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i = 16;
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for (;;) {
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grouplist = (GETGROUPS_T *) xmalloc(i * sizeof(GETGROUPS_T));
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ngroups = getgroups(i, grouplist);
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if (i > ngroups && !(ngroups == -1 && errno == EINVAL))
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break;
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/* not enough room, so try allocating a larger buffer */
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free(grouplist);
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i *= 2;
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}
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if (ngroups < 0) {
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perror("getgroups");
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exit(1);
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}
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#endif /* HAVE_SETGROUPS */
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/*
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* now we put her in the new group. the password file entry for
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* her current user id has been gotten. if there was no optional
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* group argument she will have her real and effective group id
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* set to the value from her password file entry. otherwise
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* we validate her access to the specified group.
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*/
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if (group == (char *) 0) {
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if (! (grp = getgrgid (pwd->pw_gid))) {
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fprintf (stderr, _("unknown gid: %d\n"), pwd->pw_gid);
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goto failure;
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}
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group = grp->gr_name;
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2007-10-07 17:14:14 +05:30
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their_grp = 1;
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2007-10-07 17:14:02 +05:30
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} else if (! (grp = getgrnam (group))) {
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fprintf (stderr, _("unknown group: %s\n"), group);
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goto failure;
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}
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#ifdef SHADOWGRP
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if ((sgrp = getsgnam (group))) {
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grp->gr_passwd = sgrp->sg_passwd;
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grp->gr_mem = sgrp->sg_mem;
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}
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#endif
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/*
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* see if she is a member of this group.
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* if she isn't a member, she needs to provide the
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* group password. if there is no group password, she
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* will be denied access anyway.
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2007-10-07 17:14:14 +05:30
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*
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* we also check if this is the users default group, eg.
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* they aren't a member, but this is the group listed as
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* the one they belong to in their pwd entry.
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2007-10-07 17:14:02 +05:30
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*/
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2007-10-07 17:14:14 +05:30
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if (!is_on_list(grp->gr_mem, name) && !their_grp)
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2007-10-07 17:14:02 +05:30
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needspasswd = 1;
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/*
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* if she does not have either a shadowed password,
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* or a regular password, and the group has a password,
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* she needs to give the group password.
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*/
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#ifdef SHADOWPWD
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if ((spwd = getspnam (name)))
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pwd->pw_passwd = spwd->sp_pwdp;
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#endif
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if (pwd->pw_passwd[0] == '\0' && grp->gr_passwd[0])
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needspasswd = 1;
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/*
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* now i see about letting her into the group she requested.
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* if she is the root user, i'll let her in without having to
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* prompt for the password. otherwise i ask for a password
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* if she flunked one of the tests above. note that she
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* won't have to provide the password to her login group even
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* if she isn't listed as a member.
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*/
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if (getuid () != 0 && needspasswd) {
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/*
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* get the password from her, and set the salt for
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* the decryption from the group file.
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*/
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2007-10-07 17:14:08 +05:30
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if (! (cp = getpass (_("Password: "))))
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2007-10-07 17:14:02 +05:30
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goto failure;
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/*
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* encrypt the key she gave us using the salt from
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* the password in the group file. the result of
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* this encryption must match the previously
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* encrypted value in the file.
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*/
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cpasswd = pw_encrypt (cp, grp->gr_passwd);
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strzero(cp);
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if (grp->gr_passwd[0] == '\0') {
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/*
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* there is no password, print out "Sorry" and give up
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*/
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sleep(1);
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fputs (_("Sorry.\n"), stderr);
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goto failure;
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}
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if (strcmp (cpasswd, grp->gr_passwd) != 0) {
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SYSLOG((LOG_INFO,
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"Invalid password for group `%s' from `%s'\n",
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group, name));
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sleep(1);
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fputs (_("Sorry.\n"), stderr);
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goto failure;
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}
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}
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/*
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* all successful validations pass through this point. the
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* group id will be set, and the group added to the concurrent
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* groupset.
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*/
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#ifdef USE_SYSLOG
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if (getdef_bool ("SYSLOG_SG_ENAB"))
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SYSLOG((LOG_INFO, "user `%s' switched to group `%s'\n",
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name, group));
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#endif
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gid = grp->gr_gid;
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#ifdef HAVE_SETGROUPS
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/*
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* i am going to try to add her new group id to her concurrent
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* group set. if the group id is already present i'll just
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* skip this part. if the group doesn't fit, i'll complain
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* loudly and skip this part ...
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*/
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for (i = 0;i < ngroups;i++) {
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if (gid == grouplist[i])
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break;
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}
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if (i == ngroups) {
|
2007-10-07 17:14:51 +05:30
|
|
|
if (ngroups >= sysconf(_SC_NGROUPS_MAX)) {
|
2007-10-07 17:14:02 +05:30
|
|
|
fprintf (stderr, _("too many groups\n"));
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} else {
|
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grouplist[ngroups++] = gid;
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|
if (setgroups(ngroups, grouplist)) {
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|
|
perror("setgroups");
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
#endif
|
|
|
|
|
|
|
|
okay:
|
|
|
|
/*
|
|
|
|
* i set her group id either to the value she requested, or
|
|
|
|
* to the original value if the newgrp failed.
|
|
|
|
*/
|
|
|
|
|
|
|
|
if (setgid(gid))
|
|
|
|
perror("setgid");
|
|
|
|
|
|
|
|
if (setuid(getuid())) {
|
|
|
|
perror("setuid");
|
|
|
|
exit(1);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* see if the "-c" flag was used. if it was, i just create a
|
|
|
|
* shell command for her using the argument that followed the
|
|
|
|
* "-c" flag.
|
|
|
|
*/
|
|
|
|
|
|
|
|
if (cflag) {
|
|
|
|
closelog();
|
|
|
|
execl("/bin/sh", "sh", "-c", command, (char *) 0);
|
|
|
|
if (errno == ENOENT) {
|
|
|
|
perror("/bin/sh");
|
|
|
|
exit(127);
|
|
|
|
} else {
|
|
|
|
perror("/bin/sh");
|
|
|
|
exit(126);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* i have to get the pathname of her login shell. as a favor,
|
|
|
|
* i'll try her environment for a $SHELL value first, and
|
|
|
|
* then try the password file entry. obviously this shouldn't
|
|
|
|
* be in the restricted command directory since it could be
|
|
|
|
* used to leave the restricted environment.
|
|
|
|
*/
|
|
|
|
|
|
|
|
if (! initflag && (cp = getenv ("SHELL")))
|
|
|
|
prog = cp;
|
|
|
|
else if (pwd->pw_shell && pwd->pw_shell[0])
|
|
|
|
prog = pwd->pw_shell;
|
|
|
|
else
|
|
|
|
prog = "/bin/sh";
|
|
|
|
|
|
|
|
/*
|
|
|
|
* now i try to find the basename of the login shell. this
|
|
|
|
* will become argv[0] of the spawned command.
|
|
|
|
*/
|
|
|
|
|
|
|
|
cp = Basename((char *) prog);
|
|
|
|
|
|
|
|
#ifdef SHADOWPWD
|
|
|
|
endspent ();
|
|
|
|
#endif
|
|
|
|
#ifdef SHADOWGRP
|
|
|
|
endsgent ();
|
|
|
|
#endif
|
|
|
|
endpwent ();
|
|
|
|
endgrent ();
|
|
|
|
|
|
|
|
/*
|
|
|
|
* switch back to her home directory if i am doing login
|
|
|
|
* initialization.
|
|
|
|
*/
|
|
|
|
|
|
|
|
if (initflag) {
|
|
|
|
if (chdir (pwd->pw_dir))
|
|
|
|
perror("chdir");
|
|
|
|
|
|
|
|
while (*envp) {
|
|
|
|
if (strncmp (*envp, "PATH=", 5) == 0 ||
|
|
|
|
strncmp (*envp, "HOME=", 5) == 0 ||
|
|
|
|
strncmp (*envp, "SHELL=", 6) == 0 ||
|
|
|
|
strncmp (*envp, "TERM=", 5) == 0)
|
|
|
|
addenv(*envp, NULL);
|
|
|
|
|
|
|
|
envp++;
|
|
|
|
}
|
|
|
|
} else {
|
|
|
|
while (*envp)
|
|
|
|
addenv(*envp++, NULL);
|
|
|
|
}
|
|
|
|
|
2007-10-07 17:14:08 +05:30
|
|
|
/* sanitize_env() removes $HOME from the environment (maybe it
|
|
|
|
shouldn't - please tell me if you are sure that $HOME can't
|
|
|
|
cause security problems) - add it from user's passwd entry.
|
|
|
|
*/
|
|
|
|
addenv("HOME", pwd->pw_dir);
|
|
|
|
|
2007-10-07 17:14:02 +05:30
|
|
|
/*
|
|
|
|
* exec the login shell and go away. we are trying to get
|
|
|
|
* back to the previous environment which should be the
|
|
|
|
* user's login shell.
|
|
|
|
*/
|
|
|
|
|
|
|
|
shell(prog, initflag ? (char *)0 : cp);
|
|
|
|
/*NOTREACHED*/
|
|
|
|
|
|
|
|
failure:
|
|
|
|
/*
|
|
|
|
* this is where all failures land. the group id will not
|
|
|
|
* have been set, so the setgid() below will set me to the
|
|
|
|
* original group id i had when i was invoked.
|
|
|
|
*/
|
|
|
|
|
|
|
|
/*
|
|
|
|
* only newgrp needs to re-exec the user's shell. that is
|
|
|
|
* because the shell doesn't recognize "sg", so it doesn't
|
|
|
|
* "exec" this command.
|
|
|
|
*/
|
|
|
|
|
|
|
|
if (!is_newgrp) {
|
|
|
|
closelog();
|
|
|
|
exit (1);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* The GID is still set to the old value, so now I can
|
|
|
|
* give the user back her shell.
|
|
|
|
*/
|
|
|
|
|
|
|
|
goto okay;
|
|
|
|
}
|