auth-passwd.c

   1 /* $OpenBSD: auth-passwd.c,v 1.38 2006/07/22 20:48:22 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 #include <string.h>
  45
  46 #include "packet.h"
  47 #include "buffer.h"
  48 #include "log.h"
  49 #include "servconf.h"
  50 #include "auth.h"
  51 #include "auth-options.h"
  52
  53 extern Buffer loginmsg;
  54 extern ServerOptions options;
  55
  56 #ifdef HAVE_LOGIN_CAP
  57 extern login_cap_t *lc;
  58 #endif
  59
  60
  61 #define DAY             (24L * 60 * 60) /* 1 day in seconds */
  62 #define TWO_WEEKS       (2L * 7 * DAY)  /* 2 weeks in seconds */
  63
  64 void
  65 disable_forwarding(void)
  66 {
  67         no_port_forwarding_flag = 1;
  68         no_agent_forwarding_flag = 1;
  69         no_x11_forwarding_flag = 1;
  70 }
  71
  72 /*
  73  * Tries to authenticate the user using password.  Returns true if
  74  * authentication succeeds.
  75  */
  76 int
  77 auth_password(Authctxt *authctxt, const char *password)
  78 {
  79         struct passwd * pw = authctxt->pw;
  80         int result, ok = authctxt->valid;
  81 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
  82         static int expire_checked = 0;
  83 #endif
  84
  85 #ifndef HAVE_CYGWIN
  86         if (pw->pw_uid == 0 && options.permit_root_login != PERMIT_YES)
  87                 ok = 0;
  88 #endif
  89         if (*password == '\0' && options.permit_empty_passwd == 0)
  90                 return 0;
  91
  92 #ifdef KRB5
  93         if (options.kerberos_authentication == 1) {
  94                 int ret = auth_krb5_password(authctxt, password);
  95                 if (ret == 1 || ret == 0)
  96                         return ret && ok;
  97                 /* Fall back to ordinary passwd authentication. */
  98         }
  99 #endif
 100 #ifdef HAVE_CYGWIN
 101         if (is_winnt) {
 102                 HANDLE hToken = cygwin_logon_user(pw, password);
 103
 104                 if (hToken == INVALID_HANDLE_VALUE)
 105                         return 0;
 106                 cygwin_set_impersonation_token(hToken);
 107                 return ok;
 108         }
 109 #endif
 110 #ifdef USE_PAM
 111         if (options.use_pam)
 112                 return (sshpam_auth_passwd(authctxt, password) && ok);
 113 #endif
 114 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
 115         if (!expire_checked) {
 116                 expire_checked = 1;
 117                 if (auth_shadow_pwexpired(authctxt))
 118                         authctxt->force_pwchange = 1;
 119         }
 120 #endif
 121         result = sys_auth_passwd(authctxt, password);
 122         if (authctxt->force_pwchange)
 123                 disable_forwarding();
 124         return (result && ok);
 125 }
 126
 127 #ifdef BSD_AUTH
 128 static void
 129 warn_expiry(Authctxt *authctxt, auth_session_t *as)
 130 {
 131         char buf[256];
 132         quad_t pwtimeleft, actimeleft, daysleft, pwwarntime, acwarntime;
 133
 134         pwwarntime = acwarntime = TWO_WEEKS;
 135
 136         pwtimeleft = auth_check_change(as);
 137         actimeleft = auth_check_expire(as);
 138 #ifdef HAVE_LOGIN_CAP
 139         if (authctxt->valid) {
 140                 pwwarntime = login_getcaptime(lc, "password-warn", TWO_WEEKS,
 141                     TWO_WEEKS);
 142                 acwarntime = login_getcaptime(lc, "expire-warn", TWO_WEEKS,
 143                     TWO_WEEKS);
 144         }
 145 #endif
 146         if (pwtimeleft != 0 && pwtimeleft < pwwarntime) {
 147                 daysleft = pwtimeleft / DAY + 1;
 148                 snprintf(buf, sizeof(buf),
 149                     "Your password will expire in %lld day%s.\n",
 150                     daysleft, daysleft == 1 ? "" : "s");
 151                 buffer_append(&loginmsg, buf, strlen(buf));
 152         }
 153         if (actimeleft != 0 && actimeleft < acwarntime) {
 154                 daysleft = actimeleft / DAY + 1;
 155                 snprintf(buf, sizeof(buf),
 156                     "Your account will expire in %lld day%s.\n",
 157                     daysleft, daysleft == 1 ? "" : "s");
 158                 buffer_append(&loginmsg, buf, strlen(buf));
 159         }
 160 }
 161
 162 int
 163 sys_auth_passwd(Authctxt *authctxt, const char *password)
 164 {
 165         struct passwd *pw = authctxt->pw;
 166         auth_session_t *as;
 167         static int expire_checked = 0;
 168
 169         as = auth_usercheck(pw->pw_name, authctxt->style, "auth-ssh",
 170             (char *)password);
 171         if (as == NULL)
 172                 return (0);
 173         if (auth_getstate(as) & AUTH_PWEXPIRED) {
 174                 auth_close(as);
 175                 disable_forwarding();
 176                 authctxt->force_pwchange = 1;
 177                 return (1);
 178         } else {
 179                 if (!expire_checked) {
 180                         expire_checked = 1;
 181                         warn_expiry(authctxt, as);
 182                 }
 183                 return (auth_close(as));
 184         }
 185 }
 186 #elif !defined(CUSTOM_SYS_AUTH_PASSWD)
 187 int
 188 sys_auth_passwd(Authctxt *authctxt, const char *password)
 189 {
 190         struct passwd *pw = authctxt->pw;
 191         char *encrypted_password;
 192
 193         /* Just use the supplied fake password if authctxt is invalid */
 194         char *pw_password = authctxt->valid ? shadow_pw(pw) : pw->pw_passwd;
 195
 196         /* Check for users with no password. */
 197         if (strcmp(pw_password, "") == 0 && strcmp(password, "") == 0)
 198                 return (1);
 199
 200         /* Encrypt the candidate password using the proper salt. */
 201         encrypted_password = xcrypt(password,
 202             (pw_password[0] && pw_password[1]) ? pw_password : "xx");
 203
 204         /*
 205          * Authentication is accepted if the encrypted passwords
 206          * are identical.
 207          */
 208         return (strcmp(encrypted_password, pw_password) == 0);
 209 }
 210 #endif