564 lines
13 KiB
C
564 lines
13 KiB
C
/*
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* Copyright (c) 1999 - 2002 Kungliga Tekniska Högskolan
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* (Royal Institute of Technology, Stockholm, Sweden).
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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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*
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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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*
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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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*
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* 3. Neither the name of KTH nor the names of its contributors may be
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* used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY KTH AND ITS CONTRIBUTORS ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL KTH OR ITS CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
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#include <config.h>
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RCSID("$Id: su.c,v 1.24 2002/02/19 13:01:15 joda Exp $");
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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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#ifdef HAVE_PATHS_H
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#include <paths.h>
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#endif
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#ifdef HAVE_SHADOW_H
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#include <shadow.h>
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#endif
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#include <pwd.h>
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#ifdef HAVE_OPENSSL
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#include <openssl/des.h>
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#else
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#include <des.h>
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#endif
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#ifdef KRB5
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#include <krb5.h>
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#endif
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#ifdef KRB4
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#include <krb.h>
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#include <kafs.h>
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#endif
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#include <err.h>
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#include <roken.h>
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#include <getarg.h>
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#ifndef _PATH_DEFPATH
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#define _PATH_DEFPATH "/usr/bin:/bin"
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#endif
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#ifndef _PATH_BSHELL
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#define _PATH_BSHELL "/bin/sh"
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#endif
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int kerberos_flag = 1;
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int csh_f_flag;
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int full_login;
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int env_flag;
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char *kerberos_instance = "root";
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int help_flag;
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int version_flag;
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char *cmd;
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char tkfile[256];
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struct getargs args[] = {
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{ "kerberos", 'K', arg_negative_flag, &kerberos_flag,
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"don't use kerberos" },
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{ NULL, 'f', arg_flag, &csh_f_flag,
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"don't read .cshrc" },
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{ "full", 'l', arg_flag, &full_login,
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"simulate full login" },
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{ NULL, 'm', arg_flag, &env_flag,
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"leave environment unmodified" },
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{ "instance", 'i', arg_string, &kerberos_instance,
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"root instance to use" },
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{ "command", 'c', arg_string, &cmd,
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"command to execute" },
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{ "help", 'h', arg_flag, &help_flag },
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{ "version", 0, arg_flag, &version_flag },
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};
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static void
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usage (int ret)
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{
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arg_printusage (args,
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sizeof(args)/sizeof(*args),
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NULL,
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"[login [shell arguments]]");
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exit (ret);
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}
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static void
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free_info(struct passwd *p)
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{
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free (p->pw_name);
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free (p->pw_passwd);
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free (p->pw_dir);
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free (p->pw_shell);
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free (p);
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}
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static struct passwd*
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dup_info(const struct passwd *pwd)
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{
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struct passwd *info;
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info = malloc(sizeof(*info));
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if(info == NULL)
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return NULL;
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info->pw_name = strdup(pwd->pw_name);
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info->pw_passwd = strdup(pwd->pw_passwd);
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info->pw_uid = pwd->pw_uid;
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info->pw_gid = pwd->pw_gid;
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info->pw_dir = strdup(pwd->pw_dir);
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info->pw_shell = strdup(pwd->pw_shell);
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if(info->pw_name == NULL || info->pw_passwd == NULL ||
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info->pw_dir == NULL || info->pw_shell == NULL) {
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free_info (info);
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return NULL;
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}
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return info;
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}
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#if defined(KRB4) || defined(KRB5)
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static void
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set_tkfile()
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{
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#ifndef TKT_ROOT
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#define TKT_ROOT "/tmp/tkt"
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#endif
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int fd;
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if(*tkfile != '\0')
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return;
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snprintf(tkfile, sizeof(tkfile), "%s_XXXXXX", TKT_ROOT);
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fd = mkstemp(tkfile);
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if(fd >= 0)
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close(fd);
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#ifdef KRB4
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krb_set_tkt_string(tkfile);
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#endif
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}
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#endif
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#ifdef KRB5
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static krb5_context context;
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static krb5_ccache ccache;
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static int
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krb5_verify(const struct passwd *login_info,
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const struct passwd *su_info,
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const char *kerberos_instance)
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{
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krb5_error_code ret;
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krb5_principal p;
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char *login_name = NULL;
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#if defined(HAVE_GETLOGIN) && !defined(POSIX_GETLOGIN)
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login_name = getlogin();
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#endif
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ret = krb5_init_context (&context);
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if (ret) {
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#if 0
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warnx("krb5_init_context failed: %d", ret);
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#endif
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return 1;
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}
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if (login_name == NULL || strcmp (login_name, "root") == 0)
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login_name = login_info->pw_name;
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if (strcmp (su_info->pw_name, "root") == 0)
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ret = krb5_make_principal(context, &p, NULL,
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login_name,
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kerberos_instance,
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NULL);
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else
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ret = krb5_make_principal(context, &p, NULL,
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su_info->pw_name,
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NULL);
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if(ret)
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return 1;
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if(su_info->pw_uid != 0 || krb5_kuserok(context, p, su_info->pw_name)) {
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ret = krb5_cc_gen_new(context, &krb5_mcc_ops, &ccache);
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if(ret) {
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#if 1
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krb5_warn(context, ret, "krb5_cc_gen_new");
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#endif
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krb5_free_principal (context, p);
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return 1;
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}
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ret = krb5_verify_user_lrealm(context, p, ccache, NULL, TRUE, NULL);
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krb5_free_principal (context, p);
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if(ret) {
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krb5_cc_destroy(context, ccache);
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switch (ret) {
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case KRB5_LIBOS_PWDINTR :
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break;
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case KRB5KRB_AP_ERR_BAD_INTEGRITY:
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case KRB5KRB_AP_ERR_MODIFIED:
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krb5_warnx(context, "Password incorrect");
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break;
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default :
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krb5_warn(context, ret, "krb5_verify_user");
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break;
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}
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return 1;
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}
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return 0;
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}
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krb5_free_principal (context, p);
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return 1;
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}
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static int
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krb5_start_session(void)
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{
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krb5_ccache ccache2;
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char *cc_name;
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int ret;
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ret = krb5_cc_gen_new(context, &krb5_fcc_ops, &ccache2);
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if (ret) {
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krb5_cc_destroy(context, ccache);
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return 1;
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}
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ret = krb5_cc_copy_cache(context, ccache, ccache2);
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asprintf(&cc_name, "%s:%s", krb5_cc_get_type(context, ccache2),
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krb5_cc_get_name(context, ccache2));
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esetenv("KRB5CCNAME", cc_name, 1);
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/* we want to export this even if we don't directly support KRB4 */
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set_tkfile();
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esetenv("KRBTKFILE", tkfile, 1);
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#ifdef KRB4
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/* convert creds? */
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if(k_hasafs()) {
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if (k_setpag() == 0)
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krb5_afslog(context, ccache2, NULL, NULL);
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}
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#endif
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krb5_cc_close(context, ccache2);
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krb5_cc_destroy(context, ccache);
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return 0;
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}
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#endif
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#ifdef KRB4
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static int
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krb_verify(const struct passwd *login_info,
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const struct passwd *su_info,
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const char *kerberos_instance)
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{
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int ret;
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char *login_name = NULL;
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char *name, *instance, realm[REALM_SZ];
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#if defined(HAVE_GETLOGIN) && !defined(POSIX_GETLOGIN)
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login_name = getlogin();
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#endif
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ret = krb_get_lrealm(realm, 1);
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if (login_name == NULL || strcmp (login_name, "root") == 0)
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login_name = login_info->pw_name;
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if (strcmp (su_info->pw_name, "root") == 0) {
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name = login_name;
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instance = (char*)kerberos_instance;
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} else {
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name = su_info->pw_name;
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instance = "";
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}
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if(su_info->pw_uid != 0 ||
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krb_kuserok(name, instance, realm, su_info->pw_name) == 0) {
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char password[128];
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char *prompt;
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asprintf (&prompt,
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"%s's Password: ",
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krb_unparse_name_long (name, instance, realm));
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if (des_read_pw_string (password, sizeof (password), prompt, 0)) {
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memset (password, 0, sizeof (password));
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free(prompt);
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return (1);
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}
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free(prompt);
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if (strlen(password) == 0)
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return (1); /* Empty passwords are not allowed */
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set_tkfile();
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setuid(geteuid()); /* need to run as root here */
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ret = krb_verify_user(name, instance, realm, password,
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KRB_VERIFY_SECURE, NULL);
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memset(password, 0, sizeof(password));
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if(ret) {
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warnx("%s", krb_get_err_text(ret));
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return 1;
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}
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chown (tkt_string(), su_info->pw_uid, su_info->pw_gid);
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return 0;
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}
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return 1;
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}
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static int
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krb_start_session(void)
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{
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esetenv("KRBTKFILE", tkfile, 1);
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/* convert creds? */
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if(k_hasafs() && k_setpag() == 0)
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krb_afslog(NULL, NULL);
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return 0;
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}
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#endif
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static int
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verify_unix(struct passwd *su)
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{
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char prompt[128];
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char pw_buf[1024];
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char *pw;
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int r;
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if(su->pw_passwd != NULL && *su->pw_passwd != '\0') {
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snprintf(prompt, sizeof(prompt), "%s's password: ", su->pw_name);
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r = des_read_pw_string(pw_buf, sizeof(pw_buf), prompt, 0);
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if(r != 0)
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exit(0);
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pw = crypt(pw_buf, su->pw_passwd);
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memset(pw_buf, 0, sizeof(pw_buf));
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if(strcmp(pw, su->pw_passwd) != 0)
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return 1;
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}
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return 0;
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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 i, optind = 0;
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char *su_user;
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struct passwd *su_info;
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struct passwd *login_info;
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struct passwd *pwd;
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char *shell;
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int ok = 0;
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int kerberos_error=1;
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setprogname (argv[0]);
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if(getarg(args, sizeof(args) / sizeof(args[0]), argc, argv, &optind))
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usage(1);
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for (i=0; i < optind; i++)
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if (strcmp(argv[i], "-") == 0) {
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full_login = 1;
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break;
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}
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if(help_flag)
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usage(0);
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if(version_flag) {
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print_version(NULL);
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exit(0);
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}
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if(optind >= argc)
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su_user = "root";
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else
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su_user = argv[optind++];
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pwd = k_getpwnam(su_user);
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if(pwd == NULL)
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errx (1, "unknown login %s", su_user);
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if (pwd->pw_uid == 0 && strcmp ("root", su_user) != 0) {
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syslog (LOG_ALERT, "NIS attack, user %s has uid 0", su_user);
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errx (1, "unknown login %s", su_user);
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}
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su_info = dup_info(pwd);
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if (su_info == NULL)
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errx (1, "malloc: out of memory");
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pwd = getpwuid(getuid());
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if(pwd == NULL)
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errx(1, "who are you?");
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login_info = dup_info(pwd);
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if (login_info == NULL)
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errx (1, "malloc: out of memory");
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if(env_flag)
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shell = login_info->pw_shell;
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else
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shell = su_info->pw_shell;
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if(shell == NULL || *shell == '\0')
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shell = _PATH_BSHELL;
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#ifdef KRB5
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if(kerberos_flag && ok == 0 &&
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(kerberos_error=krb5_verify(login_info, su_info, kerberos_instance)) == 0)
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ok = 5;
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#endif
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#ifdef KRB4
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if(kerberos_flag && ok == 0 &&
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(kerberos_error = krb_verify(login_info, su_info, kerberos_instance)) == 0)
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ok = 4;
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#endif
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if(ok == 0 && login_info->pw_uid && verify_unix(su_info) != 0) {
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printf("Sorry!\n");
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exit(1);
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}
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#ifdef HAVE_GETSPNAM
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{ struct spwd *sp;
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long today;
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sp = getspnam(su_info->pw_name);
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if (sp != NULL) {
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today = time(0)/(24L * 60 * 60);
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if (sp->sp_expire > 0) {
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if (today >= sp->sp_expire) {
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if (login_info->pw_uid)
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errx(1,"Your account has expired.");
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else
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printf("Your account has expired.");
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}
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else if (sp->sp_expire - today < 14)
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printf("Your account will expire in %d days.\n",
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(int)(sp->sp_expire - today));
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}
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if (sp->sp_max > 0) {
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if (today >= sp->sp_lstchg + sp->sp_max) {
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if (login_info->pw_uid)
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errx(1,"Your password has expired. Choose a new one.");
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else
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printf("Your password has expired. Choose a new one.");
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}
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else if (today >= sp->sp_lstchg + sp->sp_max - sp->sp_warn)
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printf("Your account will expire in %d days.\n",
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(int)(sp->sp_lstchg + sp->sp_max -today));
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}
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}
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}
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#endif
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{
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char *tty = ttyname (STDERR_FILENO);
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syslog (LOG_NOTICE | LOG_AUTH, tty ? "%s to %s" : "%s to %s on %s",
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login_info->pw_name, su_info->pw_name, tty);
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}
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if(!env_flag) {
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if(full_login) {
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char *t = getenv ("TERM");
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environ = malloc (10 * sizeof (char *));
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if (environ == NULL)
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err (1, "malloc");
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environ[0] = NULL;
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esetenv ("PATH", _PATH_DEFPATH, 1);
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if (t)
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esetenv ("TERM", t, 1);
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if (chdir (su_info->pw_dir) < 0)
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errx (1, "no directory");
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}
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if (full_login || su_info->pw_uid)
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esetenv ("USER", su_info->pw_name, 1);
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esetenv("HOME", su_info->pw_dir, 1);
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esetenv("SHELL", shell, 1);
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}
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{
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int i;
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char **args;
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char *p;
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p = strrchr(shell, '/');
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if(p)
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p++;
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else
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p = shell;
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if (strcmp(p, "csh") != 0)
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csh_f_flag = 0;
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args = malloc(((cmd ? 2 : 0) + 1 + argc - optind + 1 + csh_f_flag) * sizeof(*args));
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if (args == NULL)
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err (1, "malloc");
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i = 0;
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if(full_login)
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asprintf(&args[i++], "-%s", p);
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else
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args[i++] = p;
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if (cmd) {
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args[i++] = "-c";
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args[i++] = cmd;
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}
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if (csh_f_flag)
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args[i++] = "-f";
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for (argv += optind; *argv; ++argv)
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args[i++] = *argv;
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|
args[i] = NULL;
|
|
|
|
if(setgid(su_info->pw_gid) < 0)
|
|
err(1, "setgid");
|
|
if (initgroups (su_info->pw_name, su_info->pw_gid) < 0)
|
|
err (1, "initgroups");
|
|
if(setuid(su_info->pw_uid) < 0
|
|
|| (su_info->pw_uid != 0 && setuid(0) == 0))
|
|
err(1, "setuid");
|
|
|
|
#ifdef KRB5
|
|
if (ok == 5)
|
|
krb5_start_session();
|
|
#endif
|
|
#ifdef KRB4
|
|
if (ok == 4)
|
|
krb_start_session();
|
|
#endif
|
|
{
|
|
char **p;
|
|
for(p = args; *p; p++)
|
|
printf("%s ", *p);
|
|
printf("\n");
|
|
}
|
|
execv(shell, args);
|
|
}
|
|
|
|
exit(1);
|
|
}
|