1 /* $NetBSD: auth-passwd.c,v 1.13 2023/07/07 07:04:17 rin Exp $ */
2 /* $OpenBSD: auth-passwd.c,v 1.48 2020/10/18 11:32:01 djm Exp $ */
3
4 /*
5 * Author: Tatu Ylonen <ylo@cs.hut.fi>
6 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
7 * All rights reserved
8 * Password authentication. This file contains the functions to check whether
9 * the password is valid for the user.
10 *
11 * As far as I am concerned, the code I have written for this software
12 * can be used freely for any purpose. Any derived versions of this
13 * software must be clearly marked as such, and if the derived work is
14 * incompatible with the protocol description in the RFC file, it must be
15 * called by a name other than "ssh" or "Secure Shell".
16 *
17 * Copyright (c) 1999 Dug Song. All rights reserved.
18 * Copyright (c) 2000 Markus Friedl. All rights reserved.
19 *
20 * Redistribution and use in source and binary forms, with or without
21 * modification, are permitted provided that the following conditions
22 * are met:
23 * 1. Redistributions of source code must retain the above copyright
24 * notice, this list of conditions and the following disclaimer.
25 * 2. Redistributions in binary form must reproduce the above copyright
26 * notice, this list of conditions and the following disclaimer in the
27 * documentation and/or other materials provided with the distribution.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
30 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
31 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
32 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
33 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
34 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
38 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 */
40
41 #include "includes.h"
42 __RCSID("$NetBSD: auth-passwd.c,v 1.13 2023/07/07 07:04:17 rin Exp $");
43 #include <sys/types.h>
44
45 #include <login_cap.h>
46 #include <pwd.h>
47 #include <stdio.h>
48 #include <string.h>
49 #include <stdarg.h>
50 #include <unistd.h>
51
52 #include "packet.h"
53 #include "sshbuf.h"
54 #include "ssherr.h"
55 #include "log.h"
56 #include "misc.h"
57 #include "servconf.h"
58 #include "sshkey.h"
59 #include "hostfile.h"
60 #include "auth.h"
61 #include "auth-options.h"
62
63 extern struct sshbuf *loginmsg;
64 extern ServerOptions options;
65 int sys_auth_passwd(struct ssh *, const char *);
66
67 #ifdef HAVE_LOGIN_CAP
68 extern login_cap_t *lc;
69 #endif
70
71 #define DAY (24L * 60 * 60) /* 1 day in seconds */
72 #define TWO_WEEKS (2L * 7 * DAY) /* 2 weeks in seconds */
73
74 #define MAX_PASSWORD_LEN 1024
75
76 /*
77 * Tries to authenticate the user using password. Returns true if
78 * authentication succeeds.
79 */
80 int
auth_password(struct ssh * ssh,const char * password)81 auth_password(struct ssh *ssh, const char *password)
82 {
83 Authctxt *authctxt = ssh->authctxt;
84 struct passwd *pw = authctxt->pw;
85 int ok = authctxt->valid;
86
87 if (strlen(password) > MAX_PASSWORD_LEN)
88 return 0;
89
90 if (pw->pw_uid == 0 && options.permit_root_login != PERMIT_YES)
91 ok = 0;
92 if (*password == '\0' && options.permit_empty_passwd == 0)
93 return 0;
94 #ifdef KRB5
95 if (options.kerberos_authentication == 1) {
96 int ret = auth_krb5_password(authctxt, password);
97 if (ret == 1 || ret == 0)
98 return ret && ok;
99 /* Fall back to ordinary passwd authentication. */
100 }
101 #endif
102
103 #ifdef USE_PAM
104 if (options.use_pam)
105 return (sshpam_auth_passwd(authctxt, password) && ok);
106 #endif
107 return (sys_auth_passwd(ssh, password) && ok);
108 }
109
110 #ifdef BSD_AUTH
111 static void
warn_expiry(Authctxt * authctxt,auth_session_t * as)112 warn_expiry(Authctxt *authctxt, auth_session_t *as)
113 {
114 int r;
115 quad_t pwtimeleft, actimeleft, daysleft, pwwarntime, acwarntime;
116
117 pwwarntime = acwarntime = TWO_WEEKS;
118
119 pwtimeleft = auth_check_change(as);
120 actimeleft = auth_check_expire(as);
121 #ifdef HAVE_LOGIN_CAP
122 if (authctxt->valid) {
123 pwwarntime = login_getcaptime(lc, "password-warn", TWO_WEEKS,
124 TWO_WEEKS);
125 acwarntime = login_getcaptime(lc, "expire-warn", TWO_WEEKS,
126 TWO_WEEKS);
127 }
128 #endif
129 if (pwtimeleft != 0 && pwtimeleft < pwwarntime) {
130 daysleft = pwtimeleft / DAY + 1;
131 if ((r = sshbuf_putf(loginmsg,
132 "Your password will expire in %lld day%s.\n",
133 daysleft, daysleft == 1 ? "" : "s")) != 0)
134 fatal_fr(r, "buffer error");
135 }
136 if (actimeleft != 0 && actimeleft < acwarntime) {
137 daysleft = actimeleft / DAY + 1;
138 if ((r = sshbuf_putf(loginmsg,
139 "Your account will expire in %lld day%s.\n",
140 daysleft, daysleft == 1 ? "" : "s")) != 0)
141 fatal_fr(r, "buffer error");
142 }
143 }
144
145 int
sys_auth_passwd(struct ssh * ssh,const char * password)146 sys_auth_passwd(struct ssh *ssh, const char *password)
147 {
148 Authctxt *authctxt = ssh->authctxt;
149 auth_session_t *as;
150 static int expire_checked = 0;
151
152 as = auth_usercheck(authctxt->pw->pw_name, authctxt->style, "auth-ssh",
153 (char *)password);
154 if (as == NULL)
155 return (0);
156 if (auth_getstate(as) & AUTH_PWEXPIRED) {
157 auth_close(as);
158 auth_restrict_session(ssh);
159 authctxt->force_pwchange = 1;
160 return (1);
161 } else {
162 if (!expire_checked) {
163 expire_checked = 1;
164 warn_expiry(authctxt, as);
165 }
166 return (auth_close(as));
167 }
168 }
169 #else
170
171 #define shadow_pw(pw) (pw)->pw_passwd
172 #define xcrypt(a, b) crypt((a), (b))
173
174 int
sys_auth_passwd(struct ssh * ssh,const char * password)175 sys_auth_passwd(struct ssh *ssh, const char *password)
176 {
177 Authctxt *authctxt = ssh->authctxt;
178 struct passwd *pw = authctxt->pw;
179 char *encrypted_password, *salt = NULL;
180
181 /* Just use the supplied fake password if authctxt is invalid */
182 char *pw_password = authctxt->valid ? shadow_pw(pw) : pw->pw_passwd;
183
184 /* Check for users with no password. */
185 if (strcmp(pw_password, "") == 0 && strcmp(password, "") == 0)
186 return (1);
187
188 /*
189 * Encrypt the candidate password using the proper salt, or pass a
190 * NULL and let xcrypt pick one.
191 */
192 if (authctxt->valid && pw_password[0] && pw_password[1])
193 salt = pw_password;
194 encrypted_password = xcrypt(password, salt ? salt : "xx");
195
196 /*
197 * Authentication is accepted if the encrypted passwords
198 * are identical.
199 */
200 return encrypted_password != NULL &&
201 strcmp(encrypted_password, pw_password) == 0;
202 }
203 #endif
204