513 lines
12 KiB
C
513 lines
12 KiB
C
/* $NetBSD: su_pam.c,v 1.5 2005/02/25 21:49:43 christos Exp $ */
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/*
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* Copyright (c) 1988 The Regents of the University of California.
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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 the University 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 THE REGENTS 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 THE REGENTS 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 <sys/cdefs.h>
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#ifndef lint
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__COPYRIGHT(
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"@(#) Copyright (c) 1988 The Regents of the University of California.\n\
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All rights reserved.\n");
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#endif /* not lint */
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#ifndef lint
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#if 0
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static char sccsid[] = "@(#)su.c 8.3 (Berkeley) 4/2/94";*/
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#else
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__RCSID("$NetBSD: su_pam.c,v 1.5 2005/02/25 21:49:43 christos Exp $");
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#endif
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#endif /* not lint */
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#include <sys/param.h>
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#include <sys/time.h>
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#include <sys/resource.h>
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#include <sys/wait.h>
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#include <err.h>
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#include <errno.h>
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#include <grp.h>
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#include <paths.h>
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#include <pwd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <syslog.h>
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#include <time.h>
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#include <tzfile.h>
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#include <unistd.h>
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#include <login_cap.h>
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#include <security/pam_appl.h>
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#include <security/openpam.h> /* for openpam_ttyconv() */
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static const struct pam_conv pamc = { &openpam_ttyconv, NULL };
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static int chshell(const char *);
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static char *ontty(void);
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int main(int, char **);
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#define ARGSTRX "-dflm"
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#ifdef LOGIN_CAP
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#define ARGSTR ARGSTRX "c:"
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#else
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#define ARGSTR ARGSTRX
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#endif
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int
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main(int argc, char **argv)
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{
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extern char **environ;
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struct passwd *pwd;
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char *p;
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uid_t ruid;
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int asme, ch, asthem, fastlogin, prio, gohome, setwhat;
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enum { UNSET, YES, NO } iscsh = UNSET;
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char *user, *shell, *avshell, *username, **np;
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char *class;
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char shellbuf[MAXPATHLEN], avshellbuf[MAXPATHLEN];
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int pam_err;
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char hostname[MAXHOSTNAMELEN];
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char *tty;
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const char *func;
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const void *newuser;
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login_cap_t *lc;
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pam_handle_t *pamh = NULL;
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#ifdef PAM_DEBUG
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extern int _openpam_debug;
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_openpam_debug = 1;
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#endif
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asme = asthem = fastlogin = 0;
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gohome = 1;
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shell = class = NULL;
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while ((ch = getopt(argc, argv, ARGSTR)) != -1)
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switch((char)ch) {
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case 'c':
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class = optarg;
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break;
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case 'd':
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asme = 0;
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asthem = 1;
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gohome = 0;
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break;
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case 'f':
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fastlogin = 1;
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break;
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case '-':
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case 'l':
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asme = 0;
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asthem = 1;
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break;
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case 'm':
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asme = 1;
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asthem = 0;
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break;
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case '?':
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default:
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(void)fprintf(stderr,
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"Usage: %s [%s] [login [shell arguments]]\n",
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getprogname(), ARGSTR);
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exit(1);
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}
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argv += optind;
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/* Lower the priority so su runs faster */
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errno = 0;
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prio = getpriority(PRIO_PROCESS, 0);
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if (errno)
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prio = 0;
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if (prio > -2)
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(void)setpriority(PRIO_PROCESS, 0, -2);
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openlog("su", 0, LOG_AUTH);
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/* get current login name and shell */
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ruid = getuid();
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username = getlogin();
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if (username == NULL || (pwd = getpwnam(username)) == NULL ||
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pwd->pw_uid != ruid)
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pwd = getpwuid(ruid);
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if (pwd == NULL)
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errx(1, "who are you?");
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if ((username = strdup(pwd->pw_name)) == NULL)
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err(1, "strdup");
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if (asme) {
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if (pwd->pw_shell && *pwd->pw_shell) {
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strlcpy(shellbuf, pwd->pw_shell, sizeof(shellbuf));
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shell = shellbuf;
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} else {
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shell = _PATH_BSHELL;
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iscsh = NO;
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}
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}
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/* get target login information, default to root */
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user = *argv ? *argv : "root";
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np = *argv ? argv : argv - 1;
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if ((pwd = getpwnam(user)) == NULL)
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errx(1, "unknown login %s", user);
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/*
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* PAM initialization
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*/
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#define PAM_END(msg) do { func = msg; goto done; } while (/*CONSTCOND*/0)
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if ((pam_err = pam_start("su", user, &pamc, &pamh)) != PAM_SUCCESS) {
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if (pamh != NULL)
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PAM_END("pam_start");
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/* Things went really bad... */
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syslog(LOG_ERR, "pam_start failed: %s",
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pam_strerror(pamh, pam_err));
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errx(1, "pam_start failed");
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}
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#define PAM_END_ITEM(item) PAM_END("pam_set_item(" # item ")")
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#define PAM_SET_ITEM(item, var) \
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if ((pam_err = pam_set_item(pamh, (item), (var))) != PAM_SUCCESS) \
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PAM_END_ITEM(item)
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/*
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* Fill hostname, username and tty
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*/
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PAM_SET_ITEM(PAM_RUSER, username);
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if (gethostname(hostname, sizeof(hostname)) != -1)
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PAM_SET_ITEM(PAM_RHOST, hostname);
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if ((tty = ttyname(STDERR_FILENO)) != NULL)
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PAM_SET_ITEM(PAM_TTY, tty);
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/*
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* Authentication
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*/
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if ((pam_err = pam_authenticate(pamh, 0)) != PAM_SUCCESS) {
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syslog(LOG_WARNING, "BAD SU %s to %s%s: %s",
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username, user, ontty(), pam_strerror(pamh, pam_err));
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pam_end(pamh, pam_err);
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errx(1, "Sorry: %s", pam_strerror(pamh, pam_err));
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}
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/*
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* Authorization
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*/
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switch(pam_err = pam_acct_mgmt(pamh, 0)) {
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case PAM_NEW_AUTHTOK_REQD:
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pam_err = pam_chauthtok(pamh, PAM_CHANGE_EXPIRED_AUTHTOK);
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if (pam_err != PAM_SUCCESS)
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PAM_END("pam_chauthok");
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break;
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case PAM_SUCCESS:
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break;
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default:
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PAM_END("pam_acct_mgmt");
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break;
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}
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/*
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* pam_authenticate might have changed the target user.
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* refresh pwd and user
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*/
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pam_err = pam_get_item(pamh, PAM_USER, &newuser);
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if (pam_err != PAM_SUCCESS) {
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syslog(LOG_WARNING,
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"pam_get_item(PAM_USER): %s", pam_strerror(pamh, pam_err));
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} else {
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user = (char *)newuser;
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if ((pwd = getpwnam(user)) == NULL) {
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pam_end(pamh, pam_err);
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syslog(LOG_ERR, "unknown login: %s", username);
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errx(1, "unknown login: %s", username);
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}
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}
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#define ERRX_PAM_END(args) do { \
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pam_end(pamh, pam_err); \
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errx args; \
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} while (/* CONSTOCOND */0)
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#define ERR_PAM_END(args) do { \
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pam_end(pamh, pam_err); \
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err args; \
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} while (/* CONSTOCOND */0)
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/* force the usage of specified class */
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if (class) {
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if (ruid)
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ERRX_PAM_END((1, "Only root may use -c"));
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pwd->pw_class = class;
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}
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if ((lc = login_getclass(pwd->pw_class)) == NULL)
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ERRX_PAM_END((1, "Unknown class %s\n", pwd->pw_class));
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if (asme) {
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/* if asme and non-standard target shell, must be root */
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if (!chshell(pwd->pw_shell) && ruid)
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ERRX_PAM_END((1,"permission denied (shell)."));
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} else if (pwd->pw_shell && *pwd->pw_shell) {
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shell = pwd->pw_shell;
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iscsh = UNSET;
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} else {
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shell = _PATH_BSHELL;
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iscsh = NO;
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}
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if ((p = strrchr(shell, '/')) != NULL)
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avshell = p + 1;
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else
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avshell = shell;
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/* if we're forking a csh, we want to slightly muck the args */
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if (iscsh == UNSET)
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iscsh = strstr(avshell, "csh") ? YES : NO;
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/*
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* Initialize the supplemental groups before pam gets to them,
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* so that other pam modules get a chance to add more when
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* we do setcred. Note, we don't relinguish our set-userid yet
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*/
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if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) < 0)
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ERR_PAM_END((1, "setting user context"));
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if ((pam_err = pam_setcred(pamh, PAM_ESTABLISH_CRED)) != PAM_SUCCESS)
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PAM_END("pam_setcred");
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/*
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* Manage session.
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*/
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if (asthem) {
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pid_t pid, xpid;
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void *oint;
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void *oabrt;
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int status;
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if ((pam_err = pam_open_session(pamh, 0)) != PAM_SUCCESS)
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PAM_END("pam_open_session");
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/*
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* In order to call pam_close_session after the
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* command terminates, we need to fork.
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* Make sure signals cannot kill the parent.
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* This is copied from crontab(8), which has to
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* cope with a similar situation. XXX FreeBSD
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* has a much more complicated code (CVS logs
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* tell about workaround in libpthread, but we
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* might miss useful stuff)
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*/
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oint = signal(SIGINT, SIG_IGN);
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oabrt = signal(SIGABRT, SIG_IGN);
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switch (pid = fork()) {
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case -1:
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pam_err = pam_close_session(pamh, 0);
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if (pam_err != PAM_SUCCESS) {
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syslog(LOG_ERR, "pam_close_session: %s",
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pam_strerror(pamh, pam_err));
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warnx("pam_close_session: %s",
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pam_strerror(pamh, pam_err));
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}
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ERR_PAM_END((1, "fork"));
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break;
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case 0: /* Child */
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break;
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default:
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/*
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* Parent: wait for the child to terminate
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* and call pam_close_session.
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*/
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if ((xpid = waitpid(pid, &status, 0)) != pid) {
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pam_err = pam_close_session(pamh, 0);
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if (pam_err != PAM_SUCCESS) {
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syslog(LOG_ERR,
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"pam_close_session: %s",
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pam_strerror(pamh, pam_err));
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warnx("pam_close_session: %s",
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pam_strerror(pamh, pam_err));
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}
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if (xpid == -1) {
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ERR_PAM_END((1,
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"error waiting for pid %d", pid));
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} else {
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// Can't happen.
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ERRX_PAM_END((1,
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"wrong PID: %d != %d", pid, xpid));
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}
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}
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(void)signal(SIGINT, oint);
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(void)signal(SIGABRT, oabrt);
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pam_err = pam_close_session(pamh, 0);
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if (pam_err != PAM_SUCCESS)
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PAM_END("pam_open_session");
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pam_end(pamh, PAM_SUCCESS);
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exit(0);
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break;
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}
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}
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/*
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* The child: starting here, we don't have to care about
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* handling PAM issues if we exit, the parent will do the
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* job when we exit.
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*/
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#undef PAM_END
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#undef ERR_PAM_END
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#undef ERRX_PAM_END
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if (!asme) {
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if (asthem) {
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char **pamenv;
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p = getenv("TERM");
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/*
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* Create an empty environment
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*/
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if ((environ = malloc(sizeof(char *))) == NULL)
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err(1, NULL);
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environ[0] = NULL;
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/*
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* Add PAM environement, before the LOGIN_CAP stuff:
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* if the login class is unspecified, we'll get the
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* same data from PAM, if -c was used, the specified
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* class must override PAM.
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*/
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if ((pamenv = pam_getenvlist(pamh)) != NULL) {
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char **envitem;
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/*
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* XXX Here FreeBSD filters out
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* SHELL, LOGNAME, MAIL, CDPATH, IFS, PATH
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* how could we get untrusted data here?
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*/
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for (envitem = pamenv; *envitem; envitem++) {
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putenv(*envitem);
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free(*envitem);
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}
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free(pamenv);
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}
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if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETPATH))
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err(1, "setting user context");
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if (p)
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(void)setenv("TERM", p, 1);
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if (gohome && chdir(pwd->pw_dir) < 0)
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errx(1, "no directory");
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}
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if (asthem || pwd->pw_uid)
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(void)setenv("USER", pwd->pw_name, 1);
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(void)setenv("HOME", pwd->pw_dir, 1);
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(void)setenv("SHELL", shell, 1);
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}
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(void)setenv("SU_FROM", username, 1);
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if (iscsh == YES) {
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if (fastlogin)
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*np-- = "-f";
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if (asme)
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*np-- = "-m";
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} else {
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if (fastlogin)
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unsetenv("ENV");
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}
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if (asthem) {
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avshellbuf[0] = '-';
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(void)strlcpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 1);
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avshell = avshellbuf;
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} else if (iscsh == YES) {
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/* csh strips the first character... */
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avshellbuf[0] = '_';
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(void)strlcpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 1);
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avshell = avshellbuf;
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}
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*np = avshell;
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if (ruid != 0)
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syslog(LOG_NOTICE, "%s to %s%s",
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username, pwd->pw_name, ontty());
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/*
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* Set user context, except for umask, and the stuff
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* we have done before.
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*/
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setwhat = LOGIN_SETALL & ~(LOGIN_SETENV|LOGIN_SETUMASK|
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LOGIN_SETLOGIN|LOGIN_SETPATH|LOGIN_SETGROUP);
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/*
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* Don't touch resource/priority settings if -m has been used
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* or -l and -c hasn't, and we're not su'ing to root.
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*/
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if ((asme || (!asthem && class == NULL)) && pwd->pw_uid)
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setwhat &= ~(LOGIN_SETPRIORITY|LOGIN_SETRESOURCES);
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if (setusercontext(lc, pwd, pwd->pw_uid, setwhat) == -1)
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err(1, "setusercontext");
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(void)execv(shell, np);
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err(1, "%s", shell);
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done:
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syslog(LOG_ERR, "%s: %s", func, pam_strerror(pamh, pam_err));
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warnx("%s: %s", func, pam_strerror(pamh, pam_err));
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pam_end(pamh, pam_err);
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return 1;
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}
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static int
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chshell(const char *sh)
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{
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const char *cp;
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setusershell();
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while ((cp = getusershell()) != NULL)
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if (!strcmp(cp, sh))
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return 1;
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return 0;
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}
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static char *
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ontty(void)
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{
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char *p;
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static char buf[MAXPATHLEN + 4];
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buf[0] = 0;
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if ((p = ttyname(STDERR_FILENO)) != NULL)
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(void)snprintf(buf, sizeof buf, " on %s", p);
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return buf;
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}
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