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 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 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 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 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