auth-passwd.c revision 149753 
1/*
2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 *                    All rights reserved
5 * Password authentication.  This file contains the functions to check whether
6 * the password is valid for the user.
7 *
8 * As far as I am concerned, the code I have written for this software
9 * can be used freely for any purpose.  Any derived versions of this
10 * software must be clearly marked as such, and if the derived work is
11 * incompatible with the protocol description in the RFC file, it must be
12 * called by a name other than "ssh" or "Secure Shell".
13 *
14 * Copyright (c) 1999 Dug Song.  All rights reserved.
15 * Copyright (c) 2000 Markus Friedl.  All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
19 * are met:
20 * 1. Redistributions of source code must retain the above copyright
21 *    notice, this list of conditions and the following disclaimer.
22 * 2. Redistributions in binary form must reproduce the above copyright
23 *    notice, this list of conditions and the following disclaimer in the
24 *    documentation and/or other materials provided with the distribution.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36 */
37
38#include "includes.h"
39RCSID("$OpenBSD: auth-passwd.c,v 1.34 2005/07/19 15:32:26 otto Exp $");
40RCSID("$FreeBSD: head/crypto/openssh/auth-passwd.c 149753 2005-09-03 07:04:25Z des $");
41
42#include "packet.h"
43#include "buffer.h"
44#include "log.h"
45#include "servconf.h"
46#include "auth.h"
47#include "auth-options.h"
48
49extern Buffer loginmsg;
50extern ServerOptions options;
51
52#ifdef HAVE_LOGIN_CAP
53extern login_cap_t *lc;
54#endif
55
56
57#define DAY		(24L * 60 * 60) /* 1 day in seconds */
58#define TWO_WEEKS	(2L * 7 * DAY)	/* 2 weeks in seconds */
59
60void
61disable_forwarding(void)
62{
63	no_port_forwarding_flag = 1;
64	no_agent_forwarding_flag = 1;
65	no_x11_forwarding_flag = 1;
66}
67
68/*
69 * Tries to authenticate the user using password.  Returns true if
70 * authentication succeeds.
71 */
72int
73auth_password(Authctxt *authctxt, const char *password)
74{
75	struct passwd * pw = authctxt->pw;
76	int result, ok = authctxt->valid;
77#if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
78	static int expire_checked = 0;
79#endif
80
81#ifndef HAVE_CYGWIN
82	if (pw->pw_uid == 0 && options.permit_root_login != PERMIT_YES)
83		ok = 0;
84#endif
85	if (*password == '\0' && options.permit_empty_passwd == 0)
86		return 0;
87
88#ifdef KRB5
89	if (options.kerberos_authentication == 1) {
90		int ret = auth_krb5_password(authctxt, password);
91		if (ret == 1 || ret == 0)
92			return ret && ok;
93		/* Fall back to ordinary passwd authentication. */
94	}
95#endif
96#ifdef HAVE_CYGWIN
97	if (is_winnt) {
98		HANDLE hToken = cygwin_logon_user(pw, password);
99
100		if (hToken == INVALID_HANDLE_VALUE)
101			return 0;
102		cygwin_set_impersonation_token(hToken);
103		return ok;
104	}
105#endif
106#ifdef USE_PAM
107	if (options.use_pam)
108		return (sshpam_auth_passwd(authctxt, password) && ok);
109#endif
110#if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
111	if (!expire_checked) {
112		expire_checked = 1;
113		if (auth_shadow_pwexpired(authctxt))
114			authctxt->force_pwchange = 1;
115	}
116#endif
117	result = sys_auth_passwd(authctxt, password);
118	if (authctxt->force_pwchange)
119		disable_forwarding();
120	return (result && ok);
121}
122
123#ifdef BSD_AUTH
124static void
125warn_expiry(Authctxt *authctxt, auth_session_t *as)
126{
127	char buf[256];
128	quad_t pwtimeleft, actimeleft, daysleft, pwwarntime, acwarntime;
129
130	pwwarntime = acwarntime = TWO_WEEKS;
131
132	pwtimeleft = auth_check_change(as);
133	actimeleft = auth_check_expire(as);
134#ifdef HAVE_LOGIN_CAP
135	if (authctxt->valid) {
136		pwwarntime = login_getcaptime(lc, "password-warn", TWO_WEEKS,
137		    TWO_WEEKS);
138		acwarntime = login_getcaptime(lc, "expire-warn", TWO_WEEKS,
139		    TWO_WEEKS);
140	}
141#endif
142	if (pwtimeleft != 0 && pwtimeleft < pwwarntime) {
143		daysleft = pwtimeleft / DAY + 1;
144		snprintf(buf, sizeof(buf),
145		    "Your password will expire in %lld day%s.\n",
146		    daysleft, daysleft == 1 ? "" : "s");
147		buffer_append(&loginmsg, buf, strlen(buf));
148	}
149	if (actimeleft != 0 && actimeleft < acwarntime) {
150		daysleft = actimeleft / DAY + 1;
151		snprintf(buf, sizeof(buf),
152		    "Your account will expire in %lld day%s.\n",
153		    daysleft, daysleft == 1 ? "" : "s");
154		buffer_append(&loginmsg, buf, strlen(buf));
155	}
156}
157
158int
159sys_auth_passwd(Authctxt *authctxt, const char *password)
160{
161	struct passwd *pw = authctxt->pw;
162	auth_session_t *as;
163	static int expire_checked = 0;
164
165	as = auth_usercheck(pw->pw_name, authctxt->style, "auth-ssh",
166	    (char *)password);
167	if (as == NULL)
168		return (0);
169	if (auth_getstate(as) & AUTH_PWEXPIRED) {
170		auth_close(as);
171		disable_forwarding();
172		authctxt->force_pwchange = 1;
173		return (1);
174	} else {
175		if (!expire_checked) {
176			expire_checked = 1;
177			warn_expiry(authctxt, as);
178		}
179		return (auth_close(as));
180	}
181}
182#elif !defined(CUSTOM_SYS_AUTH_PASSWD)
183int
184sys_auth_passwd(Authctxt *authctxt, const char *password)
185{
186	struct passwd *pw = authctxt->pw;
187	char *encrypted_password;
188
189	/* Just use the supplied fake password if authctxt is invalid */
190	char *pw_password = authctxt->valid ? shadow_pw(pw) : pw->pw_passwd;
191
192	/* Check for users with no password. */
193	if (strcmp(pw_password, "") == 0 && strcmp(password, "") == 0)
194		return (1);
195
196	/* Encrypt the candidate password using the proper salt. */
197	encrypted_password = xcrypt(password,
198	    (pw_password[0] && pw_password[1]) ? pw_password : "xx");
199
200	/*
201	 * Authentication is accepted if the encrypted passwords
202	 * are identical.
203	 */
204	return (strcmp(encrypted_password, pw_password) == 0);
205}
206#endif
207