auth-passwd.c

   1 /* $OpenBSD: auth-passwd.c,v 1.37 2006/07/06 16:03:53 stevesk 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
  45 #include "packet.h"
  46 #include "buffer.h"
  47 #include "log.h"
  48 #include "servconf.h"
  49 #include "auth.h"
  50 #include "auth-options.h"
  51
  52 extern Buffer loginmsg;
  53 extern ServerOptions options;
  54
  55 #ifdef HAVE_LOGIN_CAP
  56 extern login_cap_t *lc;
  57 #endif
  58
  59
  60 #define DAY             (24L * 60 * 60) /* 1 day in seconds */
  61 #define TWO_WEEKS       (2L * 7 * DAY)  /* 2 weeks in seconds */
  62
  63 void
  64 disable_forwarding(void)
  65 {
  66         no_port_forwarding_flag = 1;
  67         no_agent_forwarding_flag = 1;
  68         no_x11_forwarding_flag = 1;
  69 }
  70
  71 /*
  72  * Tries to authenticate the user using password.  Returns true if
  73  * authentication succeeds.
  74  */
  75 int
  76 auth_password(Authctxt *authctxt, const char *password)
  77 {
  78         struct passwd * pw = authctxt->pw;
  79         int result, ok = authctxt->valid;
  80 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
  81         static int expire_checked = 0;
  82 #endif
  83
  84 #ifndef HAVE_CYGWIN
  85         if (pw->pw_uid == 0 && options.permit_root_login != PERMIT_YES)
  86                 ok = 0;
  87 #endif
  88         if (*password == '\0' && options.permit_empty_passwd == 0)
  89                 return 0;
  90
  91 #ifdef KRB5
  92         if (options.kerberos_authentication == 1) {
  93                 int ret = auth_krb5_password(authctxt, password);
  94                 if (ret == 1 || ret == 0)
  95                         return ret && ok;
  96                 /* Fall back to ordinary passwd authentication. */
  97         }
  98 #endif
  99 #ifdef HAVE_CYGWIN
 100         if (is_winnt) {
 101                 HANDLE hToken = cygwin_logon_user(pw, password);
 102
 103                 if (hToken == INVALID_HANDLE_VALUE)
 104                         return 0;
 105                 cygwin_set_impersonation_token(hToken);
 106                 return ok;
 107         }
 108 #endif
 109 #ifdef USE_PAM
 110         if (options.use_pam)
 111                 return (sshpam_auth_passwd(authctxt, password) && ok);
 112 #endif
 113 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
 114         if (!expire_checked) {
 115                 expire_checked = 1;
 116                 if (auth_shadow_pwexpired(authctxt))
 117                         authctxt->force_pwchange = 1;
 118         }
 119 #endif
 120         result = sys_auth_passwd(authctxt, password);
 121         if (authctxt->force_pwchange)
 122                 disable_forwarding();
 123         return (result && ok);
 124 }
 125
 126 #ifdef BSD_AUTH
 127 static void
 128 warn_expiry(Authctxt *authctxt, auth_session_t *as)
 129 {
 130         char buf[256];
 131         quad_t pwtimeleft, actimeleft, daysleft, pwwarntime, acwarntime;
 132
 133         pwwarntime = acwarntime = TWO_WEEKS;
 134
 135         pwtimeleft = auth_check_change(as);
 136         actimeleft = auth_check_expire(as);
 137 #ifdef HAVE_LOGIN_CAP
 138         if (authctxt->valid) {
 139                 pwwarntime = login_getcaptime(lc, "password-warn", TWO_WEEKS,
 140                     TWO_WEEKS);
 141                 acwarntime = login_getcaptime(lc, "expire-warn", TWO_WEEKS,
 142                     TWO_WEEKS);
 143         }
 144 #endif
 145         if (pwtimeleft != 0 && pwtimeleft < pwwarntime) {
 146                 daysleft = pwtimeleft / DAY + 1;
 147                 snprintf(buf, sizeof(buf),
 148                     "Your password will expire in %lld day%s.\n",
 149                     daysleft, daysleft == 1 ? "" : "s");
 150                 buffer_append(&loginmsg, buf, strlen(buf));
 151         }
 152         if (actimeleft != 0 && actimeleft < acwarntime) {
 153                 daysleft = actimeleft / DAY + 1;
 154                 snprintf(buf, sizeof(buf),
 155                     "Your account will expire in %lld day%s.\n",
 156                     daysleft, daysleft == 1 ? "" : "s");
 157                 buffer_append(&loginmsg, buf, strlen(buf));
 158         }
 159 }
 160
 161 int
 162 sys_auth_passwd(Authctxt *authctxt, const char *password)
 163 {
 164         struct passwd *pw = authctxt->pw;
 165         auth_session_t *as;
 166         static int expire_checked = 0;
 167
 168         as = auth_usercheck(pw->pw_name, authctxt->style, "auth-ssh",
 169             (char *)password);
 170         if (as == NULL)
 171                 return (0);
 172         if (auth_getstate(as) & AUTH_PWEXPIRED) {
 173                 auth_close(as);
 174                 disable_forwarding();
 175                 authctxt->force_pwchange = 1;
 176                 return (1);
 177         } else {
 178                 if (!expire_checked) {
 179                         expire_checked = 1;
 180                         warn_expiry(authctxt, as);
 181                 }
 182                 return (auth_close(as));
 183         }
 184 }
 185 #elif !defined(CUSTOM_SYS_AUTH_PASSWD)
 186 int
 187 sys_auth_passwd(Authctxt *authctxt, const char *password)
 188 {
 189         struct passwd *pw = authctxt->pw;
 190         char *encrypted_password;
 191
 192         /* Just use the supplied fake password if authctxt is invalid */
 193         char *pw_password = authctxt->valid ? shadow_pw(pw) : pw->pw_passwd;
 194
 195         /* Check for users with no password. */
 196         if (strcmp(pw_password, "") == 0 && strcmp(password, "") == 0)
 197                 return (1);
 198
 199         /* Encrypt the candidate password using the proper salt. */
 200         encrypted_password = xcrypt(password,
 201             (pw_password[0] && pw_password[1]) ? pw_password : "xx");
 202
 203         /*
 204          * Authentication is accepted if the encrypted passwords
 205          * are identical.
 206          */
 207         return (strcmp(encrypted_password, pw_password) == 0);
 208 }
 209 #endif