crypto/openssh/auth-passwd.c

   1 /* $OpenBSD: auth-passwd.c,v 1.44 2014/07/15 15:54:14 millert 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 void
  70 disable_forwarding(void)
  71 {
  72         no_port_forwarding_flag = 1;
  73         no_agent_forwarding_flag = 1;
  74         no_x11_forwarding_flag = 1;
  75 }
  76
  77 /*
  78  * Tries to authenticate the user using password.  Returns true if
  79  * authentication succeeds.
  80  */
  81 int
  82 auth_password(Authctxt *authctxt, const char *password)
  83 {
  84         struct passwd * pw = authctxt->pw;
  85         int result, ok = authctxt->valid;
  86 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
  87         static int expire_checked = 0;
  88 #endif
  89
  90 #ifndef HAVE_CYGWIN
  91         if (pw->pw_uid == 0 && options.permit_root_login != PERMIT_YES)
  92                 ok = 0;
  93 #endif
  94         if (*password == '\0' && options.permit_empty_passwd == 0)
  95                 return 0;
  96
  97 #ifdef KRB5
  98         if (options.kerberos_authentication == 1) {
  99                 int ret = auth_krb5_password(authctxt, password);
 100                 if (ret == 1 || ret == 0)
 101                         return ret && ok;
 102                 /* Fall back to ordinary passwd authentication. */
 103         }
 104 #endif
 105 #ifdef HAVE_CYGWIN
 106         {
 107                 HANDLE hToken = cygwin_logon_user(pw, password);
 108
 109                 if (hToken == INVALID_HANDLE_VALUE)
 110                         return 0;
 111                 cygwin_set_impersonation_token(hToken);
 112                 return ok;
 113         }
 114 #endif
 115 #ifdef USE_PAM
 116         if (options.use_pam)
 117                 return (sshpam_auth_passwd(authctxt, password) && ok);
 118 #endif
 119 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
 120         if (!expire_checked) {
 121                 expire_checked = 1;
 122                 if (auth_shadow_pwexpired(authctxt))
 123                         authctxt->force_pwchange = 1;
 124         }
 125 #endif
 126         result = sys_auth_passwd(authctxt, password);
 127         if (authctxt->force_pwchange)
 128                 disable_forwarding();
 129         return (result && ok);
 130 }
 131
 132 #ifdef BSD_AUTH
 133 static void
 134 warn_expiry(Authctxt *authctxt, auth_session_t *as)
 135 {
 136         char buf[256];
 137         quad_t pwtimeleft, actimeleft, daysleft, pwwarntime, acwarntime;
 138
 139         pwwarntime = acwarntime = TWO_WEEKS;
 140
 141         pwtimeleft = auth_check_change(as);
 142         actimeleft = auth_check_expire(as);
 143 #ifdef HAVE_LOGIN_CAP
 144         if (authctxt->valid) {
 145                 pwwarntime = login_getcaptime(lc, "password-warn", TWO_WEEKS,
 146                     TWO_WEEKS);
 147                 acwarntime = login_getcaptime(lc, "expire-warn", TWO_WEEKS,
 148                     TWO_WEEKS);
 149         }
 150 #endif
 151         if (pwtimeleft != 0 && pwtimeleft < pwwarntime) {
 152                 daysleft = pwtimeleft / DAY + 1;
 153                 snprintf(buf, sizeof(buf),
 154                     "Your password will expire in %lld day%s.\n",
 155                     daysleft, daysleft == 1 ? "" : "s");
 156                 buffer_append(&loginmsg, buf, strlen(buf));
 157         }
 158         if (actimeleft != 0 && actimeleft < acwarntime) {
 159                 daysleft = actimeleft / DAY + 1;
 160                 snprintf(buf, sizeof(buf),
 161                     "Your account will expire in %lld day%s.\n",
 162                     daysleft, daysleft == 1 ? "" : "s");
 163                 buffer_append(&loginmsg, buf, strlen(buf));
 164         }
 165 }
 166
 167 int
 168 sys_auth_passwd(Authctxt *authctxt, const char *password)
 169 {
 170         struct passwd *pw = authctxt->pw;
 171         auth_session_t *as;
 172         static int expire_checked = 0;
 173
 174         as = auth_usercheck(pw->pw_name, authctxt->style, "auth-ssh",
 175             (char *)password);
 176         if (as == NULL)
 177                 return (0);
 178         if (auth_getstate(as) & AUTH_PWEXPIRED) {
 179                 auth_close(as);
 180                 disable_forwarding();
 181                 authctxt->force_pwchange = 1;
 182                 return (1);
 183         } else {
 184                 if (!expire_checked) {
 185                         expire_checked = 1;
 186                         warn_expiry(authctxt, as);
 187                 }
 188                 return (auth_close(as));
 189         }
 190 }
 191 #elif !defined(CUSTOM_SYS_AUTH_PASSWD)
 192 int
 193 sys_auth_passwd(Authctxt *authctxt, const char *password)
 194 {
 195         struct passwd *pw = authctxt->pw;
 196         char *encrypted_password;
 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         /* Check for users with no password. */
 202         if (strcmp(pw_password, "") == 0 && strcmp(password, "") == 0)
 203                 return (1);
 204
 205         /* Encrypt the candidate password using the proper salt. */
 206         encrypted_password = xcrypt(password,
 207             (pw_password[0] && pw_password[1]) ? pw_password : "xx");
 208
 209         /*
 210          * Authentication is accepted if the encrypted passwords
 211          * are identical.
 212          */
 213         return encrypted_password != NULL &&
 214             strcmp(encrypted_password, pw_password) == 0;
 215 }
 216 #endif