auth-passwd.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * Password authentication.  This file contains the functions to check whether
   6  * the password is valid for the user.
   7  *
   8  * As far as I am concerned, the code I have written for this software
   9  * can be used freely for any purpose.  Any derived versions of this
  10  * software must be clearly marked as such, and if the derived work is
  11  * incompatible with the protocol description in the RFC file, it must be
  12  * called by a name other than "ssh" or "Secure Shell".
  13  *
  14  * Copyright (c) 1999 Dug Song.  All rights reserved.
  15  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  16  *
  17  * Redistribution and use in source and binary forms, with or without
  18  * modification, are permitted provided that the following conditions
  19  * are met:
  20  * 1. Redistributions of source code must retain the above copyright
  21  *    notice, this list of conditions and the following disclaimer.
  22  * 2. Redistributions in binary form must reproduce the above copyright
  23  *    notice, this list of conditions and the following disclaimer in the
  24  *    documentation and/or other materials provided with the distribution.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  27  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  28  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  29  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  30  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  31  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  35  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  */
  37
  38 #include "includes.h"
  39 RCSID("$OpenBSD: auth-passwd.c,v 1.33 2005/01/24 11:47:13 dtucker Exp $");
  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 int sys_auth_passwd(Authctxt *, const char *);
  51
  52 #ifdef HAVE_LOGIN_CAP
  53 extern login_cap_t *lc;
  54 #endif
  55
  56
  57 #define DAY             (24L * 60 * 60) /* 1 day in seconds */
  58 #define TWO_WEEKS       (2L * 7 * DAY)  /* 2 weeks in seconds */
  59
  60 void
  61 disable_forwarding(void)
  62 {
  63         no_port_forwarding_flag = 1;
  64         no_agent_forwarding_flag = 1;
  65         no_x11_forwarding_flag = 1;
  66 }
  67
  68 /*
  69  * Tries to authenticate the user using password.  Returns true if
  70  * authentication succeeds.
  71  */
  72 int
  73 auth_password(Authctxt *authctxt, const char *password)
  74 {
  75         struct passwd * pw = authctxt->pw;
  76         int result, ok = authctxt->valid;
  77 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
  78         static int expire_checked = 0;
  79 #endif
  80
  81 #ifndef HAVE_CYGWIN
  82         if (pw->pw_uid == 0 && options.permit_root_login != PERMIT_YES)
  83                 ok = 0;
  84 #endif
  85         if (*password == '\0' && options.permit_empty_passwd == 0)
  86                 return 0;
  87
  88 #ifdef KRB5
  89         if (options.kerberos_authentication == 1) {
  90                 int ret = auth_krb5_password(authctxt, password);
  91                 if (ret == 1 || ret == 0)
  92                         return ret && ok;
  93                 /* Fall back to ordinary passwd authentication. */
  94         }
  95 #endif
  96 #ifdef HAVE_CYGWIN
  97         if (is_winnt) {
  98                 HANDLE hToken = cygwin_logon_user(pw, password);
  99
 100                 if (hToken == INVALID_HANDLE_VALUE)
 101                         return 0;
 102                 cygwin_set_impersonation_token(hToken);
 103                 return ok;
 104         }
 105 #endif
 106 #ifdef USE_PAM
 107         if (options.use_pam)
 108                 return (sshpam_auth_passwd(authctxt, password) && ok);
 109 #endif
 110 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
 111         if (!expire_checked) {
 112                 expire_checked = 1;
 113                 if (auth_shadow_pwexpired(authctxt))
 114                         authctxt->force_pwchange = 1;
 115         }
 116 #endif
 117         result = sys_auth_passwd(authctxt, password);
 118         if (authctxt->force_pwchange)
 119                 disable_forwarding();
 120         return (result && ok);
 121 }
 122
 123 #ifdef BSD_AUTH
 124 static void
 125 warn_expiry(Authctxt *authctxt, auth_session_t *as)
 126 {
 127         char buf[256];
 128         quad_t pwtimeleft, actimeleft, daysleft, pwwarntime, acwarntime;
 129
 130         pwwarntime = acwarntime = TWO_WEEKS;
 131
 132         pwtimeleft = auth_check_change(as);
 133         actimeleft = auth_check_expire(as);
 134 #ifdef HAVE_LOGIN_CAP
 135         if (authctxt->valid) {
 136                 pwwarntime = login_getcaptime(lc, "password-warn", TWO_WEEKS,
 137                     TWO_WEEKS);
 138                 acwarntime = login_getcaptime(lc, "expire-warn", TWO_WEEKS,
 139                     TWO_WEEKS);
 140         }
 141 #endif
 142         if (pwtimeleft != 0 && pwtimeleft < pwwarntime) {
 143                 daysleft = pwtimeleft / DAY + 1;
 144                 snprintf(buf, sizeof(buf),
 145                     "Your password will expire in %lld day%s.\n",
 146                     daysleft, daysleft == 1 ? "" : "s");
 147                 buffer_append(&loginmsg, buf, strlen(buf));
 148         }
 149         if (actimeleft != 0 && actimeleft < acwarntime) {
 150                 daysleft = actimeleft / DAY + 1;
 151                 snprintf(buf, sizeof(buf),
 152                     "Your account will expire in %lld day%s.\n",
 153                     daysleft, daysleft == 1 ? "" : "s");
 154                 buffer_append(&loginmsg, buf, strlen(buf));
 155         }
 156 }
 157
 158 int
 159 sys_auth_passwd(Authctxt *authctxt, const char *password)
 160 {
 161         struct passwd *pw = authctxt->pw;
 162         auth_session_t *as;
 163         static int expire_checked = 0;
 164
 165         as = auth_usercheck(pw->pw_name, authctxt->style, "auth-ssh",
 166             (char *)password);
 167         if (auth_getstate(as) & AUTH_PWEXPIRED) {
 168                 auth_close(as);
 169                 disable_forwarding();
 170                 authctxt->force_pwchange = 1;
 171                 return (1);
 172         } else {
 173                 if (!expire_checked) {
 174                         expire_checked = 1;
 175                         warn_expiry(authctxt, as);
 176                 }
 177                 return (auth_close(as));
 178         }
 179 }
 180 #elif !defined(CUSTOM_SYS_AUTH_PASSWD)
 181 int
 182 sys_auth_passwd(Authctxt *authctxt, const char *password)
 183 {
 184         struct passwd *pw = authctxt->pw;
 185         char *encrypted_password;
 186
 187         /* Just use the supplied fake password if authctxt is invalid */
 188         char *pw_password = authctxt->valid ? shadow_pw(pw) : pw->pw_passwd;
 189
 190         /* Check for users with no password. */
 191         if (strcmp(pw_password, "") == 0 && strcmp(password, "") == 0)
 192                 return (1);
 193
 194         /* Encrypt the candidate password using the proper salt. */
 195         encrypted_password = xcrypt(password,
 196             (pw_password[0] && pw_password[1]) ? pw_password : "xx");
 197
 198         /*
 199          * Authentication is accepted if the encrypted passwords
 200          * are identical.
 201          */
 202         return (strcmp(encrypted_password, pw_password) == 0);
 203 }
 204 #endif