1 /* $OpenBSD: auth-passwd.c,v 1.46 2018/03/03 03:15:51 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 "misc.h" 52 #include "servconf.h" 53 #include "key.h" 54 #include "hostfile.h" 55 #include "auth.h" 56 #include "auth-options.h" 57 58 extern Buffer loginmsg; 59 extern ServerOptions options; 60 61 #ifdef HAVE_LOGIN_CAP 62 extern login_cap_t *lc; 63 #endif 64 65 66 #define DAY (24L * 60 * 60) /* 1 day in seconds */ 67 #define TWO_WEEKS (2L * 7 * DAY) /* 2 weeks in seconds */ 68 69 #define MAX_PASSWORD_LEN 1024 70 71 /* 72 * Tries to authenticate the user using password. Returns true if 73 * authentication succeeds. 74 */ 75 int 76 auth_password(struct ssh *ssh, const char *password) 77 { 78 Authctxt *authctxt = ssh->authctxt; 79 struct passwd *pw = authctxt->pw; 80 int result, ok = authctxt->valid; 81 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE) 82 static int expire_checked = 0; 83 #endif 84 85 if (strlen(password) > MAX_PASSWORD_LEN) 86 return 0; 87 88 #ifndef HAVE_CYGWIN 89 if (pw->pw_uid == 0 && options.permit_root_login != PERMIT_YES) 90 ok = 0; 91 #endif 92 if (*password == '\0' && options.permit_empty_passwd == 0) 93 return 0; 94 95 #ifdef KRB5 96 if (options.kerberos_authentication == 1) { 97 int ret = auth_krb5_password(authctxt, password); 98 if (ret == 1 || ret == 0) 99 return ret && ok; 100 /* Fall back to ordinary passwd authentication. */ 101 } 102 #endif 103 #ifdef HAVE_CYGWIN 104 { 105 HANDLE hToken = cygwin_logon_user(pw, password); 106 107 if (hToken == INVALID_HANDLE_VALUE) 108 return 0; 109 cygwin_set_impersonation_token(hToken); 110 return ok; 111 } 112 #endif 113 #ifdef USE_PAM 114 if (options.use_pam) 115 return (sshpam_auth_passwd(authctxt, password) && ok); 116 #endif 117 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE) 118 if (!expire_checked) { 119 expire_checked = 1; 120 if (auth_shadow_pwexpired(authctxt)) 121 authctxt->force_pwchange = 1; 122 } 123 #endif 124 result = sys_auth_passwd(ssh, password); 125 if (authctxt->force_pwchange) 126 auth_restrict_session(ssh); 127 return (result && ok); 128 } 129 130 #ifdef BSD_AUTH 131 static void 132 warn_expiry(Authctxt *authctxt, auth_session_t *as) 133 { 134 char buf[256]; 135 quad_t pwtimeleft, actimeleft, daysleft, pwwarntime, acwarntime; 136 137 pwwarntime = acwarntime = TWO_WEEKS; 138 139 pwtimeleft = auth_check_change(as); 140 actimeleft = auth_check_expire(as); 141 #ifdef HAVE_LOGIN_CAP 142 if (authctxt->valid) { 143 pwwarntime = login_getcaptime(lc, "password-warn", TWO_WEEKS, 144 TWO_WEEKS); 145 acwarntime = login_getcaptime(lc, "expire-warn", TWO_WEEKS, 146 TWO_WEEKS); 147 } 148 #endif 149 if (pwtimeleft != 0 && pwtimeleft < pwwarntime) { 150 daysleft = pwtimeleft / DAY + 1; 151 snprintf(buf, sizeof(buf), 152 "Your password will expire in %lld day%s.\n", 153 daysleft, daysleft == 1 ? "" : "s"); 154 buffer_append(&loginmsg, buf, strlen(buf)); 155 } 156 if (actimeleft != 0 && actimeleft < acwarntime) { 157 daysleft = actimeleft / DAY + 1; 158 snprintf(buf, sizeof(buf), 159 "Your account will expire in %lld day%s.\n", 160 daysleft, daysleft == 1 ? "" : "s"); 161 buffer_append(&loginmsg, buf, strlen(buf)); 162 } 163 } 164 165 int 166 sys_auth_passwd(struct ssh *ssh, const char *password) 167 { 168 Authctxt *authctxt = ssh->authctxt; 169 auth_session_t *as; 170 static int expire_checked = 0; 171 172 as = auth_usercheck(authctxt->pw->pw_name, authctxt->style, "auth-ssh", 173 (char *)password); 174 if (as == NULL) 175 return (0); 176 if (auth_getstate(as) & AUTH_PWEXPIRED) { 177 auth_close(as); 178 auth_restrict_session(ssh); 179 authctxt->force_pwchange = 1; 180 return (1); 181 } else { 182 if (!expire_checked) { 183 expire_checked = 1; 184 warn_expiry(authctxt, as); 185 } 186 return (auth_close(as)); 187 } 188 } 189 #elif !defined(CUSTOM_SYS_AUTH_PASSWD) 190 int 191 sys_auth_passwd(struct ssh *ssh, const char *password) 192 { 193 Authctxt *authctxt = ssh->authctxt; 194 struct passwd *pw = authctxt->pw; 195 char *encrypted_password, *salt = NULL; 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 /* 205 * Encrypt the candidate password using the proper salt, or pass a 206 * NULL and let xcrypt pick one. 207 */ 208 if (authctxt->valid && pw_password[0] && pw_password[1]) 209 salt = pw_password; 210 encrypted_password = xcrypt(password, salt); 211 212 /* 213 * Authentication is accepted if the encrypted passwords 214 * are identical. 215 */ 216 return encrypted_password != NULL && 217 strcmp(encrypted_password, pw_password) == 0; 218 } 219 #endif 220