crypto/openssh/auth-passwd.c

   1 /* $OpenBSD: auth-passwd.c,v 1.45 2016/07/21 01:39:35 dtucker 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 #define MAX_PASSWORD_LEN        1024
  70
  71 void
  72 disable_forwarding(void)
  73 {
  74         no_port_forwarding_flag = 1;
  75         no_agent_forwarding_flag = 1;
  76         no_x11_forwarding_flag = 1;
  77 }
  78
  79 /*
  80  * Tries to authenticate the user using password.  Returns true if
  81  * authentication succeeds.
  82  */
  83 int
  84 auth_password(Authctxt *authctxt, const char *password)
  85 {
  86         struct passwd * pw = authctxt->pw;
  87         int result, ok = authctxt->valid;
  88 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
  89         static int expire_checked = 0;
  90 #endif
  91
  92         if (strlen(password) > MAX_PASSWORD_LEN)
  93                 return 0;
  94
  95 #ifndef HAVE_CYGWIN
  96         if (pw->pw_uid == 0 && options.permit_root_login != PERMIT_YES)
  97                 ok = 0;
  98 #endif
  99         if (*password == '\0' && options.permit_empty_passwd == 0)
 100                 return 0;
 101
 102 #ifdef KRB5
 103         if (options.kerberos_authentication == 1) {
 104                 int ret = auth_krb5_password(authctxt, password);
 105                 if (ret == 1 || ret == 0)
 106                         return ret && ok;
 107                 /* Fall back to ordinary passwd authentication. */
 108         }
 109 #endif
 110 #ifdef HAVE_CYGWIN
 111         {
 112                 HANDLE hToken = cygwin_logon_user(pw, password);
 113
 114                 if (hToken == INVALID_HANDLE_VALUE)
 115                         return 0;
 116                 cygwin_set_impersonation_token(hToken);
 117                 return ok;
 118         }
 119 #endif
 120 #ifdef USE_PAM
 121         if (options.use_pam)
 122                 return (sshpam_auth_passwd(authctxt, password) && ok);
 123 #endif
 124 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
 125         if (!expire_checked) {
 126                 expire_checked = 1;
 127                 if (auth_shadow_pwexpired(authctxt))
 128                         authctxt->force_pwchange = 1;
 129         }
 130 #endif
 131         result = sys_auth_passwd(authctxt, password);
 132         if (authctxt->force_pwchange)
 133                 disable_forwarding();
 134         return (result && ok);
 135 }
 136
 137 #ifdef BSD_AUTH
 138 static void
 139 warn_expiry(Authctxt *authctxt, auth_session_t *as)
 140 {
 141         char buf[256];
 142         quad_t pwtimeleft, actimeleft, daysleft, pwwarntime, acwarntime;
 143
 144         pwwarntime = acwarntime = TWO_WEEKS;
 145
 146         pwtimeleft = auth_check_change(as);
 147         actimeleft = auth_check_expire(as);
 148 #ifdef HAVE_LOGIN_CAP
 149         if (authctxt->valid) {
 150                 pwwarntime = login_getcaptime(lc, "password-warn", TWO_WEEKS,
 151                     TWO_WEEKS);
 152                 acwarntime = login_getcaptime(lc, "expire-warn", TWO_WEEKS,
 153                     TWO_WEEKS);
 154         }
 155 #endif
 156         if (pwtimeleft != 0 && pwtimeleft < pwwarntime) {
 157                 daysleft = pwtimeleft / DAY + 1;
 158                 snprintf(buf, sizeof(buf),
 159                     "Your password will expire in %lld day%s.\n",
 160                     daysleft, daysleft == 1 ? "" : "s");
 161                 buffer_append(&loginmsg, buf, strlen(buf));
 162         }
 163         if (actimeleft != 0 && actimeleft < acwarntime) {
 164                 daysleft = actimeleft / DAY + 1;
 165                 snprintf(buf, sizeof(buf),
 166                     "Your account will expire in %lld day%s.\n",
 167                     daysleft, daysleft == 1 ? "" : "s");
 168                 buffer_append(&loginmsg, buf, strlen(buf));
 169         }
 170 }
 171
 172 int
 173 sys_auth_passwd(Authctxt *authctxt, const char *password)
 174 {
 175         struct passwd *pw = authctxt->pw;
 176         auth_session_t *as;
 177         static int expire_checked = 0;
 178
 179         as = auth_usercheck(pw->pw_name, authctxt->style, "auth-ssh",
 180             (char *)password);
 181         if (as == NULL)
 182                 return (0);
 183         if (auth_getstate(as) & AUTH_PWEXPIRED) {
 184                 auth_close(as);
 185                 disable_forwarding();
 186                 authctxt->force_pwchange = 1;
 187                 return (1);
 188         } else {
 189                 if (!expire_checked) {
 190                         expire_checked = 1;
 191                         warn_expiry(authctxt, as);
 192                 }
 193                 return (auth_close(as));
 194         }
 195 }
 196 #elif !defined(CUSTOM_SYS_AUTH_PASSWD)
 197 int
 198 sys_auth_passwd(Authctxt *authctxt, const char *password)
 199 {
 200         struct passwd *pw = authctxt->pw;
 201         char *encrypted_password, *salt = NULL;
 202
 203         /* Just use the supplied fake password if authctxt is invalid */
 204         char *pw_password = authctxt->valid ? shadow_pw(pw) : pw->pw_passwd;
 205
 206         /* Check for users with no password. */
 207         if (strcmp(pw_password, "") == 0 && strcmp(password, "") == 0)
 208                 return (1);
 209
 210         /*
 211          * Encrypt the candidate password using the proper salt, or pass a
 212          * NULL and let xcrypt pick one.
 213          */
 214         if (authctxt->valid && pw_password[0] && pw_password[1])
 215                 salt = pw_password;
 216         encrypted_password = xcrypt(password, salt);
 217
 218         /*
 219          * Authentication is accepted if the encrypted passwords
 220          * are identical.
 221          */
 222         return encrypted_password != NULL &&
 223             strcmp(encrypted_password, pw_password) == 0;
 224 }
 225 #endif