1 /* $OpenBSD: auth-passwd.c,v 1.45 2016/07/21 01:39:35 dtucker 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 void 72 disable_forwarding(void) 73 { 74 no_port_forwarding_flag = 1; 75 no_agent_forwarding_flag = 1; 76 no_x11_forwarding_flag = 1; 77 } 78 79 /* 80 * Tries to authenticate the user using password. Returns true if 81 * authentication succeeds. 82 */ 83 int 84 auth_password(Authctxt *authctxt, const char *password) 85 { 86 struct passwd * pw = authctxt->pw; 87 int result, ok = authctxt->valid; 88 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE) 89 static int expire_checked = 0; 90 #endif 91 92 if (strlen(password) > MAX_PASSWORD_LEN) 93 return 0; 94 95 #ifndef HAVE_CYGWIN 96 if (pw->pw_uid == 0 && options.permit_root_login != PERMIT_YES) 97 ok = 0; 98 #endif 99 if (*password == '\0' && options.permit_empty_passwd == 0) 100 return 0; 101 102 #ifdef KRB5 103 if (options.kerberos_authentication == 1) { 104 int ret = auth_krb5_password(authctxt, password); 105 if (ret == 1 || ret == 0) 106 return ret && ok; 107 /* Fall back to ordinary passwd authentication. */ 108 } 109 #endif 110 #ifdef HAVE_CYGWIN 111 { 112 HANDLE hToken = cygwin_logon_user(pw, password); 113 114 if (hToken == INVALID_HANDLE_VALUE) 115 return 0; 116 cygwin_set_impersonation_token(hToken); 117 return ok; 118 } 119 #endif 120 #ifdef USE_PAM 121 if (options.use_pam) 122 return (sshpam_auth_passwd(authctxt, password) && ok); 123 #endif 124 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE) 125 if (!expire_checked) { 126 expire_checked = 1; 127 if (auth_shadow_pwexpired(authctxt)) 128 authctxt->force_pwchange = 1; 129 } 130 #endif 131 result = sys_auth_passwd(authctxt, password); 132 if (authctxt->force_pwchange) 133 disable_forwarding(); 134 return (result && ok); 135 } 136 137 #ifdef BSD_AUTH 138 static void 139 warn_expiry(Authctxt *authctxt, auth_session_t *as) 140 { 141 char buf[256]; 142 quad_t pwtimeleft, actimeleft, daysleft, pwwarntime, acwarntime; 143 144 pwwarntime = acwarntime = TWO_WEEKS; 145 146 pwtimeleft = auth_check_change(as); 147 actimeleft = auth_check_expire(as); 148 #ifdef HAVE_LOGIN_CAP 149 if (authctxt->valid) { 150 pwwarntime = login_getcaptime(lc, "password-warn", TWO_WEEKS, 151 TWO_WEEKS); 152 acwarntime = login_getcaptime(lc, "expire-warn", TWO_WEEKS, 153 TWO_WEEKS); 154 } 155 #endif 156 if (pwtimeleft != 0 && pwtimeleft < pwwarntime) { 157 daysleft = pwtimeleft / DAY + 1; 158 snprintf(buf, sizeof(buf), 159 "Your password will expire in %lld day%s.\n", 160 daysleft, daysleft == 1 ? "" : "s"); 161 buffer_append(&loginmsg, buf, strlen(buf)); 162 } 163 if (actimeleft != 0 && actimeleft < acwarntime) { 164 daysleft = actimeleft / DAY + 1; 165 snprintf(buf, sizeof(buf), 166 "Your account will expire in %lld day%s.\n", 167 daysleft, daysleft == 1 ? "" : "s"); 168 buffer_append(&loginmsg, buf, strlen(buf)); 169 } 170 } 171 172 int 173 sys_auth_passwd(Authctxt *authctxt, const char *password) 174 { 175 struct passwd *pw = authctxt->pw; 176 auth_session_t *as; 177 static int expire_checked = 0; 178 179 as = auth_usercheck(pw->pw_name, authctxt->style, "auth-ssh", 180 (char *)password); 181 if (as == NULL) 182 return (0); 183 if (auth_getstate(as) & AUTH_PWEXPIRED) { 184 auth_close(as); 185 disable_forwarding(); 186 authctxt->force_pwchange = 1; 187 return (1); 188 } else { 189 if (!expire_checked) { 190 expire_checked = 1; 191 warn_expiry(authctxt, as); 192 } 193 return (auth_close(as)); 194 } 195 } 196 #elif !defined(CUSTOM_SYS_AUTH_PASSWD) 197 int 198 sys_auth_passwd(Authctxt *authctxt, const char *password) 199 { 200 struct passwd *pw = authctxt->pw; 201 char *encrypted_password, *salt = NULL; 202 203 /* Just use the supplied fake password if authctxt is invalid */ 204 char *pw_password = authctxt->valid ? shadow_pw(pw) : pw->pw_passwd; 205 206 /* Check for users with no password. */ 207 if (strcmp(pw_password, "") == 0 && strcmp(password, "") == 0) 208 return (1); 209 210 /* 211 * Encrypt the candidate password using the proper salt, or pass a 212 * NULL and let xcrypt pick one. 213 */ 214 if (authctxt->valid && pw_password[0] && pw_password[1]) 215 salt = pw_password; 216 encrypted_password = xcrypt(password, salt); 217 218 /* 219 * Authentication is accepted if the encrypted passwords 220 * are identical. 221 */ 222 return encrypted_password != NULL && 223 strcmp(encrypted_password, pw_password) == 0; 224 } 225 #endif 226