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/* $OpenBSD: auth-passwd.c,v 1.47 2018/07/09 21:26:02 markus Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* Password authentication. This file contains the functions to check whether
* the password is valid for the user.
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*
* Copyright (c) 1999 Dug Song. All rights reserved.
* Copyright (c) 2000 Markus Friedl. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
#include <sys/types.h>
#include <pwd.h>
#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include "packet.h"
#include "sshbuf.h"
#include "ssherr.h"
#include "log.h"
#include "misc.h"
#include "servconf.h"
#include "sshkey.h"
#include "hostfile.h"
#include "auth.h"
#include "auth-options.h"
extern struct sshbuf *loginmsg;
extern ServerOptions options;
#ifdef HAVE_LOGIN_CAP
extern login_cap_t *lc;
#endif
#define DAY (24L * 60 * 60) /* 1 day in seconds */
#define TWO_WEEKS (2L * 7 * DAY) /* 2 weeks in seconds */
#define MAX_PASSWORD_LEN 1024
/*
* Tries to authenticate the user using password. Returns true if
* authentication succeeds.
*/
int
auth_password(struct ssh *ssh, const char *password)
{
Authctxt *authctxt = ssh->authctxt;
struct passwd *pw = authctxt->pw;
int result, ok = authctxt->valid;
#if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
static int expire_checked = 0;
#endif
if (strlen(password) > MAX_PASSWORD_LEN)
return 0;
#ifndef HAVE_CYGWIN
if (pw->pw_uid == 0 && options.permit_root_login != PERMIT_YES)
ok = 0;
#endif
if (*password == '\0' && options.permit_empty_passwd == 0)
return 0;
#ifdef KRB5
if (options.kerberos_authentication == 1) {
int ret = auth_krb5_password(authctxt, password);
if (ret == 1 || ret == 0)
return ret && ok;
/* Fall back to ordinary passwd authentication. */
}
#endif
#ifdef HAVE_CYGWIN
{
HANDLE hToken = cygwin_logon_user(pw, password);
if (hToken == INVALID_HANDLE_VALUE)
return 0;
cygwin_set_impersonation_token(hToken);
return ok;
}
#endif
#ifdef USE_PAM
if (options.use_pam)
return (sshpam_auth_passwd(authctxt, password) && ok);
#endif
#if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
if (!expire_checked) {
expire_checked = 1;
if (auth_shadow_pwexpired(authctxt))
authctxt->force_pwchange = 1;
}
#endif
result = sys_auth_passwd(ssh, password);
if (authctxt->force_pwchange)
auth_restrict_session(ssh);
return (result && ok);
}
#ifdef BSD_AUTH
static void
warn_expiry(Authctxt *authctxt, auth_session_t *as)
{
int r;
quad_t pwtimeleft, actimeleft, daysleft, pwwarntime, acwarntime;
pwwarntime = acwarntime = TWO_WEEKS;
pwtimeleft = auth_check_change(as);
actimeleft = auth_check_expire(as);
#ifdef HAVE_LOGIN_CAP
if (authctxt->valid) {
pwwarntime = login_getcaptime(lc, "password-warn", TWO_WEEKS,
TWO_WEEKS);
acwarntime = login_getcaptime(lc, "expire-warn", TWO_WEEKS,
TWO_WEEKS);
}
#endif
if (pwtimeleft != 0 && pwtimeleft < pwwarntime) {
daysleft = pwtimeleft / DAY + 1;
if ((r = sshbuf_putf(loginmsg,
"Your password will expire in %lld day%s.\n",
daysleft, daysleft == 1 ? "" : "s")) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
if (actimeleft != 0 && actimeleft < acwarntime) {
daysleft = actimeleft / DAY + 1;
if ((r = sshbuf_putf(loginmsg,
"Your account will expire in %lld day%s.\n",
daysleft, daysleft == 1 ? "" : "s")) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
}
int
sys_auth_passwd(struct ssh *ssh, const char *password)
{
Authctxt *authctxt = ssh->authctxt;
auth_session_t *as;
static int expire_checked = 0;
as = auth_usercheck(authctxt->pw->pw_name, authctxt->style, "auth-ssh",
(char *)password);
if (as == NULL)
return (0);
if (auth_getstate(as) & AUTH_PWEXPIRED) {
auth_close(as);
auth_restrict_session(ssh);
authctxt->force_pwchange = 1;
return (1);
} else {
if (!expire_checked) {
expire_checked = 1;
warn_expiry(authctxt, as);
}
return (auth_close(as));
}
}
#elif !defined(CUSTOM_SYS_AUTH_PASSWD)
int
sys_auth_passwd(struct ssh *ssh, const char *password)
{
Authctxt *authctxt = ssh->authctxt;
struct passwd *pw = authctxt->pw;
char *encrypted_password, *salt = NULL;
/* Just use the supplied fake password if authctxt is invalid */
char *pw_password = authctxt->valid ? shadow_pw(pw) : pw->pw_passwd;
if (pw_password == NULL)
return 0;
/* Check for users with no password. */
if (strcmp(pw_password, "") == 0 && strcmp(password, "") == 0)
return (1);
/*
* Encrypt the candidate password using the proper salt, or pass a
* NULL and let xcrypt pick one.
*/
if (authctxt->valid && pw_password[0] && pw_password[1])
salt = pw_password;
encrypted_password = xcrypt(password, salt);
/*
* Authentication is accepted if the encrypted passwords
* are identical.
*/
return encrypted_password != NULL &&
strcmp(encrypted_password, pw_password) == 0;
}
#endif
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