1/* $OpenBSD: auth-passwd.c,v 1.43 2007/09/21 08:15:29 djm Exp $ */
2/*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 *                    All rights reserved
6 * Password authentication.  This file contains the functions to check whether
7 * the password is valid for the user.
8 *
9 * As far as I am concerned, the code I have written for this software
10 * can be used freely for any purpose.  Any derived versions of this
11 * software must be clearly marked as such, and if the derived work is
12 * incompatible with the protocol description in the RFC file, it must be
13 * called by a name other than "ssh" or "Secure Shell".
14 *
15 * Copyright (c) 1999 Dug Song.  All rights reserved.
16 * Copyright (c) 2000 Markus Friedl.  All rights reserved.
17 *
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions
20 * are met:
21 * 1. Redistributions of source code must retain the above copyright
22 *    notice, this list of conditions and the following disclaimer.
23 * 2. Redistributions in binary form must reproduce the above copyright
24 *    notice, this list of conditions and the following disclaimer in the
25 *    documentation and/or other materials provided with the distribution.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37 */
38
39#include "includes.h"
40
41#include <sys/types.h>
42
43#include <pwd.h>
44#include <stdio.h>
45#include <string.h>
46#include <stdarg.h>
47
48#include "packet.h"
49#include "buffer.h"
50#include "log.h"
51#include "servconf.h"
52#include "key.h"
53#include "hostfile.h"
54#include "auth.h"
55#include "auth-options.h"
56
57extern Buffer loginmsg;
58extern ServerOptions options;
59
60#ifdef HAVE_LOGIN_CAP
61extern login_cap_t *lc;
62#endif
63
64
65#define DAY		(24L * 60 * 60) /* 1 day in seconds */
66#define TWO_WEEKS	(2L * 7 * DAY)	/* 2 weeks in seconds */
67
68void
69disable_forwarding(void)
70{
71	no_port_forwarding_flag = 1;
72	no_agent_forwarding_flag = 1;
73	no_x11_forwarding_flag = 1;
74}
75
76/*
77 * Tries to authenticate the user using password.  Returns true if
78 * authentication succeeds.
79 */
80int
81auth_password(Authctxt *authctxt, const char *password)
82{
83	struct passwd * pw = authctxt->pw;
84	int result, ok = authctxt->valid;
85#if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
86	static int expire_checked = 0;
87#endif
88
89#ifndef HAVE_CYGWIN
90	if (pw->pw_uid == 0 && options.permit_root_login != PERMIT_YES)
91		ok = 0;
92#endif
93	if (*password == '\0' && options.permit_empty_passwd == 0)
94		return 0;
95
96#ifdef KRB5
97	if (options.kerberos_authentication == 1) {
98		int ret = auth_krb5_password(authctxt, password);
99		if (ret == 1 || ret == 0)
100			return ret && ok;
101		/* Fall back to ordinary passwd authentication. */
102	}
103#endif
104#ifdef HAVE_CYGWIN
105	{
106		HANDLE hToken = cygwin_logon_user(pw, password);
107
108		if (hToken == INVALID_HANDLE_VALUE)
109			return 0;
110		cygwin_set_impersonation_token(hToken);
111		return ok;
112	}
113#endif
114#ifdef USE_PAM
115	if (options.use_pam)
116		return (sshpam_auth_passwd(authctxt, password) && ok);
117#endif
118#if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
119	if (!expire_checked) {
120		expire_checked = 1;
121		if (auth_shadow_pwexpired(authctxt))
122			authctxt->force_pwchange = 1;
123	}
124#endif
125	result = sys_auth_passwd(authctxt, password);
126	if (authctxt->force_pwchange)
127		disable_forwarding();
128	return (result && ok);
129}
130
131#ifdef BSD_AUTH
132static void
133warn_expiry(Authctxt *authctxt, auth_session_t *as)
134{
135	char buf[256];
136	quad_t pwtimeleft, actimeleft, daysleft, pwwarntime, acwarntime;
137
138	pwwarntime = acwarntime = TWO_WEEKS;
139
140	pwtimeleft = auth_check_change(as);
141	actimeleft = auth_check_expire(as);
142#ifdef HAVE_LOGIN_CAP
143	if (authctxt->valid) {
144		pwwarntime = login_getcaptime(lc, "password-warn", TWO_WEEKS,
145		    TWO_WEEKS);
146		acwarntime = login_getcaptime(lc, "expire-warn", TWO_WEEKS,
147		    TWO_WEEKS);
148	}
149#endif
150	if (pwtimeleft != 0 && pwtimeleft < pwwarntime) {
151		daysleft = pwtimeleft / DAY + 1;
152		snprintf(buf, sizeof(buf),
153		    "Your password will expire in %lld day%s.\n",
154		    daysleft, daysleft == 1 ? "" : "s");
155		buffer_append(&loginmsg, buf, strlen(buf));
156	}
157	if (actimeleft != 0 && actimeleft < acwarntime) {
158		daysleft = actimeleft / DAY + 1;
159		snprintf(buf, sizeof(buf),
160		    "Your account will expire in %lld day%s.\n",
161		    daysleft, daysleft == 1 ? "" : "s");
162		buffer_append(&loginmsg, buf, strlen(buf));
163	}
164}
165
166int
167sys_auth_passwd(Authctxt *authctxt, const char *password)
168{
169	struct passwd *pw = authctxt->pw;
170	auth_session_t *as;
171	static int expire_checked = 0;
172
173	as = auth_usercheck(pw->pw_name, authctxt->style, "auth-ssh",
174	    (char *)password);
175	if (as == NULL)
176		return (0);
177	if (auth_getstate(as) & AUTH_PWEXPIRED) {
178		auth_close(as);
179		disable_forwarding();
180		authctxt->force_pwchange = 1;
181		return (1);
182	} else {
183		if (!expire_checked) {
184			expire_checked = 1;
185			warn_expiry(authctxt, as);
186		}
187		return (auth_close(as));
188	}
189}
190#elif !defined(CUSTOM_SYS_AUTH_PASSWD)
191int
192sys_auth_passwd(Authctxt *authctxt, const char *password)
193{
194	struct passwd *pw = authctxt->pw;
195	char *encrypted_password;
196
197	/* Just use the supplied fake password if authctxt is invalid */
198	char *pw_password = authctxt->valid ? shadow_pw(pw) : pw->pw_passwd;
199
200	/* Check for users with no password. */
201	if (strcmp(pw_password, "") == 0 && strcmp(password, "") == 0)
202		return (1);
203
204	/* Encrypt the candidate password using the proper salt. */
205	encrypted_password = xcrypt(password,
206	    (pw_password[0] && pw_password[1]) ? pw_password : "xx");
207
208	/*
209	 * Authentication is accepted if the encrypted passwords
210	 * are identical.
211	 */
212	return encrypted_password != NULL &&
213	    strcmp(encrypted_password, pw_password) == 0;
214}
215#endif
216