auth-passwd.c revision 137019 
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 1.31 2004/01/30 09:48:57 markus Exp $");
40RCSID("$FreeBSD: head/crypto/openssh/auth-passwd.c 137019 2004-10-28 16:11:31Z des $");
41
42#include "packet.h"
43#include "log.h"
44#include "servconf.h"
45#include "auth.h"
46#include "auth-options.h"
47
48extern ServerOptions options;
49int sys_auth_passwd(Authctxt *, const char *);
50
51void
52disable_forwarding(void)
53{
54	no_port_forwarding_flag = 1;
55	no_agent_forwarding_flag = 1;
56	no_x11_forwarding_flag = 1;
57}
58
59/*
60 * Tries to authenticate the user using password.  Returns true if
61 * authentication succeeds.
62 */
63int
64auth_password(Authctxt *authctxt, const char *password)
65{
66	struct passwd * pw = authctxt->pw;
67	int ok = authctxt->valid;
68#if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
69	static int expire_checked = 0;
70#endif
71
72#ifndef HAVE_CYGWIN
73	if (pw->pw_uid == 0 && options.permit_root_login != PERMIT_YES)
74		ok = 0;
75#endif
76	if (*password == '\0' && options.permit_empty_passwd == 0)
77		return 0;
78
79#ifdef KRB5
80	if (options.kerberos_authentication == 1) {
81		int ret = auth_krb5_password(authctxt, password);
82		if (ret == 1 || ret == 0)
83			return ret && ok;
84		/* Fall back to ordinary passwd authentication. */
85	}
86#endif
87#ifdef HAVE_CYGWIN
88	if (is_winnt) {
89		HANDLE hToken = cygwin_logon_user(pw, password);
90
91		if (hToken == INVALID_HANDLE_VALUE)
92			return 0;
93		cygwin_set_impersonation_token(hToken);
94		return ok;
95	}
96#endif
97#ifdef USE_PAM
98	if (options.use_pam)
99		return (sshpam_auth_passwd(authctxt, password) && ok);
100#endif
101#if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
102	if (!expire_checked) {
103		expire_checked = 1;
104		if (auth_shadow_pwexpired(authctxt)) {
105			disable_forwarding();
106			authctxt->force_pwchange = 1;
107		}
108	}
109#endif
110
111	return (sys_auth_passwd(authctxt, password) && ok);
112}
113
114#ifdef BSD_AUTH
115int
116sys_auth_passwd(Authctxt *authctxt, const char *password)
117{
118	struct passwd *pw = authctxt->pw;
119	auth_session_t *as;
120
121	as = auth_usercheck(pw->pw_name, authctxt->style, "auth-ssh",
122	    (char *)password);
123	if (auth_getstate(as) & AUTH_PWEXPIRED) {
124		auth_close(as);
125		disable_forwarding();
126		authctxt->force_pwchange = 1;
127		return (1);
128	} else {
129		return (auth_close(as));
130	}
131}
132#elif !defined(CUSTOM_SYS_AUTH_PASSWD)
133int
134sys_auth_passwd(Authctxt *authctxt, const char *password)
135{
136	struct passwd *pw = authctxt->pw;
137	char *encrypted_password;
138
139	/* Just use the supplied fake password if authctxt is invalid */
140	char *pw_password = authctxt->valid ? shadow_pw(pw) : pw->pw_passwd;
141
142	/* Check for users with no password. */
143	if (strcmp(pw_password, "") == 0 && strcmp(password, "") == 0)
144		return (1);
145
146	/* Encrypt the candidate password using the proper salt. */
147	encrypted_password = xcrypt(password,
148	    (pw_password[0] && pw_password[1]) ? pw_password : "xx");
149
150	/*
151	 * Authentication is accepted if the encrypted passwords
152	 * are identical.
153	 */
154	return (strcmp(encrypted_password, pw_password) == 0);
155}
156#endif
157