1 /* $OpenBSD: auth-passwd.c,v 1.48 2020/10/18 11:32:01 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 "sshbuf.h"
50 #include "ssherr.h"
51 #include "log.h"
52 #include "misc.h"
53 #include "servconf.h"
54 #include "sshkey.h"
55 #include "hostfile.h"
56 #include "auth.h"
57 #include "auth-options.h"
58
59 extern struct sshbuf *loginmsg;
60 extern ServerOptions options;
61
62 #ifdef HAVE_LOGIN_CAP
63 extern login_cap_t *lc;
64 #endif
65
66
67 #define DAY (24L * 60 * 60) /* 1 day in seconds */
68 #define TWO_WEEKS (2L * 7 * DAY) /* 2 weeks in seconds */
69
70 #define MAX_PASSWORD_LEN 1024
71
72 /*
73 * Tries to authenticate the user using password. Returns true if
74 * authentication succeeds.
75 */
76 int
auth_password(struct ssh * ssh,const char * password)77 auth_password(struct ssh *ssh, const char *password)
78 {
79 Authctxt *authctxt = ssh->authctxt;
80 struct passwd *pw = authctxt->pw;
81 int result, ok = authctxt->valid;
82 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
83 static int expire_checked = 0;
84 #endif
85
86 if (strlen(password) > MAX_PASSWORD_LEN)
87 return 0;
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(ssh, password);
126 if (authctxt->force_pwchange)
127 auth_restrict_session(ssh);
128 return (result && ok);
129 }
130
131 #ifdef BSD_AUTH
132 static void
warn_expiry(Authctxt * authctxt,auth_session_t * as)133 warn_expiry(Authctxt *authctxt, auth_session_t *as)
134 {
135 int r;
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 if ((r = sshbuf_putf(loginmsg,
153 "Your password will expire in %lld day%s.\n",
154 daysleft, daysleft == 1 ? "" : "s")) != 0)
155 fatal_fr(r, "buffer error");
156 }
157 if (actimeleft != 0 && actimeleft < acwarntime) {
158 daysleft = actimeleft / DAY + 1;
159 if ((r = sshbuf_putf(loginmsg,
160 "Your account will expire in %lld day%s.\n",
161 daysleft, daysleft == 1 ? "" : "s")) != 0)
162 fatal_fr(r, "buffer error");
163 }
164 }
165
166 int
sys_auth_passwd(struct ssh * ssh,const char * password)167 sys_auth_passwd(struct ssh *ssh, const char *password)
168 {
169 Authctxt *authctxt = ssh->authctxt;
170 auth_session_t *as;
171 static int expire_checked = 0;
172
173 as = auth_usercheck(authctxt->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 auth_restrict_session(ssh);
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)
191 int
sys_auth_passwd(struct ssh * ssh,const char * password)192 sys_auth_passwd(struct ssh *ssh, const char *password)
193 {
194 Authctxt *authctxt = ssh->authctxt;
195 struct passwd *pw = authctxt->pw;
196 char *encrypted_password, *salt = NULL;
197
198 /* Just use the supplied fake password if authctxt is invalid */
199 char *pw_password = authctxt->valid ? shadow_pw(pw) : pw->pw_passwd;
200
201 if (pw_password == NULL)
202 return 0;
203
204 /* Check for users with no password. */
205 if (strcmp(pw_password, "") == 0 && strcmp(password, "") == 0)
206 return (1);
207
208 /*
209 * Encrypt the candidate password using the proper salt, or pass a
210 * NULL and let xcrypt pick one.
211 */
212 if (authctxt->valid && pw_password[0] && pw_password[1])
213 salt = pw_password;
214 encrypted_password = xcrypt(password, salt);
215
216 /*
217 * Authentication is accepted if the encrypted passwords
218 * are identical.
219 */
220 return encrypted_password != NULL &&
221 strcmp(encrypted_password, pw_password) == 0;
222 }
223 #endif
224