311 lines
9.1 KiB
C
311 lines
9.1 KiB
C
/* $OpenBSD: auth-passwd.c,v 1.47 2018/07/09 21:26:02 markus Exp $ */
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/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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* All rights reserved
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* Password authentication. This file contains the functions to check whether
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* the password is valid for the user.
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*
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* As far as I am concerned, the code I have written for this software
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* can be used freely for any purpose. Any derived versions of this
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* software must be clearly marked as such, and if the derived work is
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* incompatible with the protocol description in the RFC file, it must be
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* called by a name other than "ssh" or "Secure Shell".
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*
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* Copyright (c) 1999 Dug Song. All rights reserved.
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* Copyright (c) 2000 Markus Friedl. 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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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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#include <sys/types.h>
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#include <pwd.h>
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#include <stdio.h>
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#include <string.h>
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#include <stdarg.h>
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#include "packet.h"
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#include "sshbuf.h"
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#include "ssherr.h"
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#include "log.h"
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#include "misc.h"
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#include "servconf.h"
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#include "sshkey.h"
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#include "hostfile.h"
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#include "auth.h"
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#include "auth-options.h"
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#include "authfd.h"
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#ifdef WINDOWS
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#include "w32api_proxies.h"
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#include "misc_internal.h"
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#endif
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extern struct sshbuf *loginmsg;
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extern ServerOptions options;
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#ifdef HAVE_LOGIN_CAP
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extern login_cap_t *lc;
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#endif
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#define DAY (24L * 60 * 60) /* 1 day in seconds */
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#define TWO_WEEKS (2L * 7 * DAY) /* 2 weeks in seconds */
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#define MAX_PASSWORD_LEN 1024
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/*
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* Tries to authenticate the user using password. Returns true if
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* authentication succeeds.
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*/
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int
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auth_password(struct ssh *ssh, const char *password)
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{
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Authctxt *authctxt = ssh->authctxt;
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struct passwd *pw = authctxt->pw;
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int result, ok = authctxt->valid;
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#if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
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static int expire_checked = 0;
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#endif
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if (strlen(password) > MAX_PASSWORD_LEN)
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return 0;
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#ifndef HAVE_CYGWIN
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if (pw->pw_uid == 0 && options.permit_root_login != PERMIT_YES)
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ok = 0;
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#endif
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if (*password == '\0' && options.permit_empty_passwd == 0)
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return 0;
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#ifdef KRB5
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if (options.kerberos_authentication == 1) {
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int ret = auth_krb5_password(authctxt, password);
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if (ret == 1 || ret == 0)
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return ret && ok;
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/* Fall back to ordinary passwd authentication. */
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}
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#endif
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#ifdef HAVE_CYGWIN
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{
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HANDLE hToken = cygwin_logon_user(pw, password);
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if (hToken == INVALID_HANDLE_VALUE)
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return 0;
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cygwin_set_impersonation_token(hToken);
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return ok;
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}
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#endif
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#ifdef USE_PAM
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if (options.use_pam)
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return (sshpam_auth_passwd(authctxt, password) && ok);
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#endif
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#if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
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if (!expire_checked) {
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expire_checked = 1;
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if (auth_shadow_pwexpired(authctxt))
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authctxt->force_pwchange = 1;
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}
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#endif
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result = sys_auth_passwd(ssh, password);
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if (authctxt->force_pwchange)
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auth_restrict_session(ssh);
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return (result && ok);
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}
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#ifdef BSD_AUTH
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static void
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warn_expiry(Authctxt *authctxt, auth_session_t *as)
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{
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int r;
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quad_t pwtimeleft, actimeleft, daysleft, pwwarntime, acwarntime;
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pwwarntime = acwarntime = TWO_WEEKS;
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pwtimeleft = auth_check_change(as);
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actimeleft = auth_check_expire(as);
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#ifdef HAVE_LOGIN_CAP
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if (authctxt->valid) {
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pwwarntime = login_getcaptime(lc, "password-warn", TWO_WEEKS,
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TWO_WEEKS);
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acwarntime = login_getcaptime(lc, "expire-warn", TWO_WEEKS,
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TWO_WEEKS);
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}
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#endif
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if (pwtimeleft != 0 && pwtimeleft < pwwarntime) {
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daysleft = pwtimeleft / DAY + 1;
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if ((r = sshbuf_putf(loginmsg,
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"Your password will expire in %lld day%s.\n",
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daysleft, daysleft == 1 ? "" : "s")) != 0)
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fatal("%s: buffer error: %s", __func__, ssh_err(r));
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}
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if (actimeleft != 0 && actimeleft < acwarntime) {
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daysleft = actimeleft / DAY + 1;
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if ((r = sshbuf_putf(loginmsg,
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"Your account will expire in %lld day%s.\n",
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daysleft, daysleft == 1 ? "" : "s")) != 0)
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fatal("%s: buffer error: %s", __func__, ssh_err(r));
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}
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}
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int
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sys_auth_passwd(struct ssh *ssh, const char *password)
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{
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Authctxt *authctxt = ssh->authctxt;
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auth_session_t *as;
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static int expire_checked = 0;
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as = auth_usercheck(authctxt->pw->pw_name, authctxt->style, "auth-ssh",
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(char *)password);
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if (as == NULL)
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return (0);
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if (auth_getstate(as) & AUTH_PWEXPIRED) {
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auth_close(as);
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auth_restrict_session(ssh);
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authctxt->force_pwchange = 1;
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return (1);
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} else {
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if (!expire_checked) {
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expire_checked = 1;
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warn_expiry(authctxt, as);
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}
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return (auth_close(as));
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}
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}
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#elif !defined(CUSTOM_SYS_AUTH_PASSWD)
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int
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sys_auth_passwd(struct ssh *ssh, const char *password)
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{
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Authctxt *authctxt = ssh->authctxt;
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struct passwd *pw = authctxt->pw;
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char *encrypted_password, *salt = NULL;
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/* Just use the supplied fake password if authctxt is invalid */
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char *pw_password = authctxt->valid ? shadow_pw(pw) : pw->pw_passwd;
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if (pw_password == NULL)
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return 0;
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/* Check for users with no password. */
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if (strcmp(pw_password, "") == 0 && strcmp(password, "") == 0)
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return (1);
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/*
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* Encrypt the candidate password using the proper salt, or pass a
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* NULL and let xcrypt pick one.
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*/
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if (authctxt->valid && pw_password[0] && pw_password[1])
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salt = pw_password;
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encrypted_password = xcrypt(password, salt);
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/*
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* Authentication is accepted if the encrypted passwords
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* are identical.
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*/
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return encrypted_password != NULL &&
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strcmp(encrypted_password, pw_password) == 0;
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}
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#elif defined(WINDOWS)
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HANDLE password_auth_token = NULL;
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HANDLE process_custom_lsa_auth(const char*, const char*, const char*);
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char* get_custom_lsa_package();
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/*
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* Authenticate on Windows
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* - Call LogonUser and retrieve user token
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* - If LogonUser fails, then try the LSA (Local Security Authority) authentication.
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*/
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int
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sys_auth_passwd(struct ssh *ssh, const char *password)
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{
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wchar_t *user_utf16 = NULL, *pwd_utf16 = NULL, *unam_utf16 = NULL, *udom_utf16 = L".";
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Authctxt *authctxt = ssh->authctxt;
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HANDLE token = NULL;
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WCHAR domain_upn[MAX_UPN_LEN + 1];
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ULONG domain_upn_len = ARRAYSIZE(domain_upn);
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user_utf16 = utf8_to_utf16(authctxt->pw->pw_name);
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pwd_utf16 = utf8_to_utf16(password);
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if (user_utf16 == NULL || pwd_utf16 == NULL) {
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debug("out of memory");
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goto done;
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}
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/* the format for the user will be constrained to the output of get_passwd()
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* so only the only two formats are NetBiosDomain\SamAccountName which is
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* a domain account or just SamAccountName in which is a local account */
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/* default assumption - local user */
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unam_utf16 = user_utf16;
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/* translate to domain user if format contains a backslash */
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wchar_t * backslash = wcschr(user_utf16, L'\\');
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if (backslash != NULL) {
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/* attempt to format into upn format as this is preferred for login */
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if (lookup_principal_name(user_utf16, domain_upn) == 0) {
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unam_utf16 = domain_upn;
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udom_utf16 = NULL;
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}
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/* could not discover upn so just use netbios for the domain parameter and
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* the sam account name for the user name */
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else {
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*backslash = '\0';
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unam_utf16 = backslash + 1;
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udom_utf16 = user_utf16;
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}
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}
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if (pLogonUserExExW(unam_utf16, udom_utf16, pwd_utf16, LOGON32_LOGON_NETWORK_CLEARTEXT,
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LOGON32_PROVIDER_DEFAULT, NULL, &token, NULL, NULL, NULL, NULL) == TRUE)
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password_auth_token = token;
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else {
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if (GetLastError() == ERROR_PASSWORD_MUST_CHANGE)
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/*
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* TODO - need to add support to force password change
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* by sending back SSH_MSG_USERAUTH_PASSWD_CHANGEREQ
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*/
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error("password for user %s has expired", authctxt->pw->pw_name);
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else {
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debug("Windows authentication failed for user: %ls domain: %ls error: %d",
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unam_utf16, udom_utf16, GetLastError());
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/* If LSA authentication package is configured then it will return the auth_token */
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if (get_custom_lsa_package())
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password_auth_token = process_custom_lsa_auth(authctxt->pw->pw_name, password, get_custom_lsa_package());
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}
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}
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done:
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if (user_utf16)
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free(user_utf16);
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if (pwd_utf16)
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SecureZeroMemory(pwd_utf16, sizeof(wchar_t) * wcslen(pwd_utf16));
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return (password_auth_token) ? 1 : 0;
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}
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#endif /* WINDOWS */
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