auth-passwd.c

   1 /* $OpenBSD: auth-passwd.c,v 1.36 2006/03/25 13:17:01 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 "packet.h"
  42 #include "buffer.h"
  43 #include "log.h"
  44 #include "servconf.h"
  45 #include "auth.h"
  46 #include "auth-options.h"
  47
  48 extern Buffer loginmsg;
  49 extern ServerOptions options;
  50
  51 #ifdef HAVE_LOGIN_CAP
  52 extern login_cap_t *lc;
  53 #endif
  54
  55
  56 #define DAY             (24L * 60 * 60) /* 1 day in seconds */
  57 #define TWO_WEEKS       (2L * 7 * DAY)  /* 2 weeks in seconds */
  58
  59 void
  60 disable_forwarding(void)
  61 {
  62         no_port_forwarding_flag = 1;
  63         no_agent_forwarding_flag = 1;
  64         no_x11_forwarding_flag = 1;
  65 }
  66
  67 /*
  68  * Tries to authenticate the user using password.  Returns true if
  69  * authentication succeeds.
  70  */
  71 int
  72 auth_password(Authctxt *authctxt, const char *password)
  73 {
  74         struct passwd * pw = authctxt->pw;
  75         int result, ok = authctxt->valid;
  76 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
  77         static int expire_checked = 0;
  78 #endif
  79
  80 #ifndef HAVE_CYGWIN
  81         if (pw->pw_uid == 0 && options.permit_root_login != PERMIT_YES)
  82                 ok = 0;
  83 #endif
  84         if (*password == '\0' && options.permit_empty_passwd == 0)
  85                 return 0;
  86
  87 #ifdef KRB5
  88         if (options.kerberos_authentication == 1) {
  89                 int ret = auth_krb5_password(authctxt, password);
  90                 if (ret == 1 || ret == 0)
  91                         return ret && ok;
  92                 /* Fall back to ordinary passwd authentication. */
  93         }
  94 #endif
  95 #ifdef HAVE_CYGWIN
  96         if (is_winnt) {
  97                 HANDLE hToken = cygwin_logon_user(pw, password);
  98
  99                 if (hToken == INVALID_HANDLE_VALUE)
 100                         return 0;
 101                 cygwin_set_impersonation_token(hToken);
 102                 return ok;
 103         }
 104 #endif
 105 #ifdef USE_PAM
 106         if (options.use_pam)
 107                 return (sshpam_auth_passwd(authctxt, password) && ok);
 108 #endif
 109 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
 110         if (!expire_checked) {
 111                 expire_checked = 1;
 112                 if (auth_shadow_pwexpired(authctxt))
 113                         authctxt->force_pwchange = 1;
 114         }
 115 #endif
 116         result = sys_auth_passwd(authctxt, password);
 117         if (authctxt->force_pwchange)
 118                 disable_forwarding();
 119         return (result && ok);
 120 }
 121
 122 #ifdef BSD_AUTH
 123 static void
 124 warn_expiry(Authctxt *authctxt, auth_session_t *as)
 125 {
 126         char buf[256];
 127         quad_t pwtimeleft, actimeleft, daysleft, pwwarntime, acwarntime;
 128
 129         pwwarntime = acwarntime = TWO_WEEKS;
 130
 131         pwtimeleft = auth_check_change(as);
 132         actimeleft = auth_check_expire(as);
 133 #ifdef HAVE_LOGIN_CAP
 134         if (authctxt->valid) {
 135                 pwwarntime = login_getcaptime(lc, "password-warn", TWO_WEEKS,
 136                     TWO_WEEKS);
 137                 acwarntime = login_getcaptime(lc, "expire-warn", TWO_WEEKS,
 138                     TWO_WEEKS);
 139         }
 140 #endif
 141         if (pwtimeleft != 0 && pwtimeleft < pwwarntime) {
 142                 daysleft = pwtimeleft / DAY + 1;
 143                 snprintf(buf, sizeof(buf),
 144                     "Your password will expire in %lld day%s.\n",
 145                     daysleft, daysleft == 1 ? "" : "s");
 146                 buffer_append(&loginmsg, buf, strlen(buf));
 147         }
 148         if (actimeleft != 0 && actimeleft < acwarntime) {
 149                 daysleft = actimeleft / DAY + 1;
 150                 snprintf(buf, sizeof(buf),
 151                     "Your account will expire in %lld day%s.\n",
 152                     daysleft, daysleft == 1 ? "" : "s");
 153                 buffer_append(&loginmsg, buf, strlen(buf));
 154         }
 155 }
 156
 157 int
 158 sys_auth_passwd(Authctxt *authctxt, const char *password)
 159 {
 160         struct passwd *pw = authctxt->pw;
 161         auth_session_t *as;
 162         static int expire_checked = 0;
 163
 164         as = auth_usercheck(pw->pw_name, authctxt->style, "auth-ssh",
 165             (char *)password);
 166         if (as == NULL)
 167                 return (0);
 168         if (auth_getstate(as) & AUTH_PWEXPIRED) {
 169                 auth_close(as);
 170                 disable_forwarding();
 171                 authctxt->force_pwchange = 1;
 172                 return (1);
 173         } else {
 174                 if (!expire_checked) {
 175                         expire_checked = 1;
 176                         warn_expiry(authctxt, as);
 177                 }
 178                 return (auth_close(as));
 179         }
 180 }
 181 #elif !defined(CUSTOM_SYS_AUTH_PASSWD)
 182 int
 183 sys_auth_passwd(Authctxt *authctxt, const char *password)
 184 {
 185         struct passwd *pw = authctxt->pw;
 186         char *encrypted_password;
 187
 188         /* Just use the supplied fake password if authctxt is invalid */
 189         char *pw_password = authctxt->valid ? shadow_pw(pw) : pw->pw_passwd;
 190
 191         /* Check for users with no password. */
 192         if (strcmp(pw_password, "") == 0 && strcmp(password, "") == 0)
 193                 return (1);
 194
 195         /* Encrypt the candidate password using the proper salt. */
 196         encrypted_password = xcrypt(password,
 197             (pw_password[0] && pw_password[1]) ? pw_password : "xx");
 198
 199         /*
 200          * Authentication is accepted if the encrypted passwords
 201          * are identical.
 202          */
 203         return (strcmp(encrypted_password, pw_password) == 0);
 204 }
 205 #endif