Correct PPTP server firewall rules chain.

[tomato/davidwu.git] / release / src / router / samba / source / passdb / pass_check.c

/* 
   Unix SMB/Netbios implementation.
   Version 1.9.
   Password checking
   Copyright (C) Andrew Tridgell 1992-1998
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

/* this module is for checking a username/password against a system
   password database. The SMB encrypted password support is elsewhere */

#include "includes.h"

extern int DEBUGLEVEL;

/* these are kept here to keep the string_combinations function simple */
static char this_user[100]="";
static char this_salt[100]="";
static char this_crypted[100]="";


#ifdef WITH_PAM
/*******************************************************************
check on PAM authentication
********************************************************************/

/* We first need some helper functions */
#include <security/pam_appl.h>
/* Static variables used to communicate between the conversation function
 * and the server_login function
 */
static char *PAM_username;
static char *PAM_password;

/* PAM conversation function
 * Here we assume (for now, at least) that echo on means login name, and
 * echo off means password.
 */
static int PAM_conv (int num_msg,
                     const struct pam_message **msg,
                     struct pam_response **resp,
                     void *appdata_ptr) {
  int replies = 0;
  struct pam_response *reply = NULL;

  #define COPY_STRING(s) (s) ? strdup(s) : NULL

  reply = malloc(sizeof(struct pam_response) * num_msg);
  if (!reply) return PAM_CONV_ERR;

  for (replies = 0; replies < num_msg; replies++) {
    switch (msg[replies]->msg_style) {
      case PAM_PROMPT_ECHO_ON:
        reply[replies].resp_retcode = PAM_SUCCESS;
        reply[replies].resp = COPY_STRING(PAM_username);
          /* PAM frees resp */
        break;
      case PAM_PROMPT_ECHO_OFF:
        reply[replies].resp_retcode = PAM_SUCCESS;
        reply[replies].resp = COPY_STRING(PAM_password);
          /* PAM frees resp */
        break;
      case PAM_TEXT_INFO:
        /* fall through */
      case PAM_ERROR_MSG:
        /* ignore it... */
        reply[replies].resp_retcode = PAM_SUCCESS;
        reply[replies].resp = NULL;
        break;
      default:
        /* Must be an error of some sort... */
        free (reply);
        return PAM_CONV_ERR;
    }
  }
  if (reply) *resp = reply;
  return PAM_SUCCESS;
}
static struct pam_conv PAM_conversation = {
    &PAM_conv,
    NULL
};


static BOOL pam_auth(char *user,char *password)
{
  pam_handle_t *pamh;
  int pam_error;

  /* Now use PAM to do authentication.  For now, we won't worry about
   * session logging, only authentication.  Bail out if there are any
   * errors.  Since this is a limited protocol, and an even more limited
   * function within a server speaking this protocol, we can't be as
   * verbose as would otherwise make sense.
   * Query: should we be using PAM_SILENT to shut PAM up?
   */
  #define PAM_BAIL if (pam_error != PAM_SUCCESS) { \
     pam_end(pamh, 0); return False; \
   }
  PAM_password = password;
  PAM_username = user;
  pam_error = pam_start("samba", user, &PAM_conversation, &pamh);
  PAM_BAIL;
/* Setting PAM_SILENT stops generation of error messages to syslog
 * to enable debugging on Red Hat Linux set:
 * /etc/pam.d/samba:
 *      auth required /lib/security/pam_pwdb.so nullok shadow audit
 * _OR_ change PAM_SILENT to 0 to force detailed reporting (logging)
 */
  pam_error = pam_authenticate(pamh, PAM_SILENT);
  PAM_BAIL;
  /* It is not clear to me that account management is the right thing
   * to do, but it is not clear that it isn't, either.  This can be
   * removed if no account management should be done.  Alternately,
   * put a pam_allow.so entry in /etc/pam.conf for account handling. */
  pam_error = pam_acct_mgmt(pamh, PAM_SILENT);
  PAM_BAIL;
  pam_end(pamh, PAM_SUCCESS);
  /* If this point is reached, the user has been authenticated. */
  return(True);
}
#endif


#ifdef WITH_AFS

#include <afs/stds.h>
#include <afs/kautils.h>

/*******************************************************************
check on AFS authentication
********************************************************************/
static BOOL afs_auth(char *user,char *password)
{
        long password_expires = 0;
        char *reason;
    
        /* For versions of AFS prior to 3.3, this routine has few arguments, */
        /* but since I can't find the old documentation... :-)               */
        setpag();
        if (ka_UserAuthenticateGeneral(KA_USERAUTH_VERSION+KA_USERAUTH_DOSETPAG,
                                       user,
                                       (char *) 0, /* instance */
                                       (char *) 0, /* cell */
                                       password,
                                       0,          /* lifetime, default */
                                       &password_expires, /*days 'til it expires */
                                       0,          /* spare 2 */
                                       &reason) == 0) {
                return(True);
        }
        DEBUG(1,("AFS authentication for \"%s\" failed (%s)\n", user, reason));
        return(False);
}
#endif


#ifdef WITH_DFS

#include <dce/dce_error.h>
#include <dce/sec_login.h>

/*****************************************************************
 This new version of the DFS_AUTH code was donated by Karsten Muuss
 <muuss@or.uni-bonn.de>. It fixes the following problems with the
 old code :

  - Server credentials may expire
  - Client credential cache files have wrong owner
  - purge_context() function is called with invalid argument

 This new code was modified to ensure that on exit the uid/gid is
 still root, and the original directory is restored. JRA.
******************************************************************/

sec_login_handle_t my_dce_sec_context;
int dcelogin_atmost_once = 0;

/*******************************************************************
check on a DCE/DFS authentication
********************************************************************/
static BOOL dfs_auth(char *user,char *password)
{
        error_status_t err;
        int err2;
        int prterr;
        signed32 expire_time, current_time;
        boolean32 password_reset;
        struct passwd *pw;
        sec_passwd_rec_t passwd_rec;
        sec_login_auth_src_t auth_src = sec_login_auth_src_network;
        unsigned char dce_errstr[dce_c_error_string_len];
        gid_t egid;

        if (dcelogin_atmost_once) return(False);

#ifdef HAVE_CRYPT
        /*
         * We only go for a DCE login context if the given password
         * matches that stored in the local password file.. 
         * Assumes local passwd file is kept in sync w/ DCE RGY!
         */

        if (strcmp((char *)crypt(password,this_salt),this_crypted)) {
                return(False);
        }
#endif

        sec_login_get_current_context(&my_dce_sec_context, &err);
        if (err != error_status_ok ) {  
                dce_error_inq_text(err, dce_errstr, &err2);
                DEBUG(0,("DCE can't get current context. %s\n", dce_errstr));

                return(False);
        }

        sec_login_certify_identity(my_dce_sec_context, &err);
        if (err != error_status_ok) {  
                dce_error_inq_text(err, dce_errstr, &err2);
                DEBUG(0,("DCE can't get current context. %s\n", dce_errstr));
                
                return(False);
        }

        sec_login_get_expiration(my_dce_sec_context, &expire_time, &err);
        if (err != error_status_ok) {
                dce_error_inq_text(err, dce_errstr, &err2);
                DEBUG(0,("DCE can't get expiration. %s\n", dce_errstr));
                
                return(False);
        }
  
        time(&current_time);

        if (expire_time < (current_time + 60)) {
                struct passwd    *pw;
                sec_passwd_rec_t *key;
  
                sec_login_get_pwent(my_dce_sec_context, 
                                    (sec_login_passwd_t*)&pw, &err);
                if (err != error_status_ok ) {
                        dce_error_inq_text(err, dce_errstr, &err2);
                        DEBUG(0,("DCE can't get pwent. %s\n", dce_errstr));
                        
                        return(False);
                }
                
                sec_login_refresh_identity(my_dce_sec_context, &err);
                if (err != error_status_ok) { 
                        dce_error_inq_text(err, dce_errstr, &err2);
                        DEBUG(0,("DCE can't refresh identity. %s\n", 
                                 dce_errstr));
                        
                        return(False);
                }
  
                sec_key_mgmt_get_key(rpc_c_authn_dce_secret, NULL,
                                     (unsigned char *)pw->pw_name,
                                     sec_c_key_version_none,
                                     (void**)&key, &err);
                if (err != error_status_ok) {
                        dce_error_inq_text(err, dce_errstr, &err2);
                        DEBUG(0,("DCE can't get key for %s. %s\n", 
                                 pw->pw_name, dce_errstr));

                        return(False);
                }
  
                sec_login_valid_and_cert_ident(my_dce_sec_context, key,
                                               &password_reset, &auth_src, 
                                               &err);
                if (err != error_status_ok ) {
                        dce_error_inq_text(err, dce_errstr, &err2);
                        DEBUG(0,("DCE can't validate and certify identity for %s. %s\n", 
                                 pw->pw_name, dce_errstr));
                }
  
                sec_key_mgmt_free_key(key, &err);
                if (err != error_status_ok ) {
                        dce_error_inq_text(err, dce_errstr, &err2);
                        DEBUG(0,("DCE can't free key.\n", dce_errstr));
                }
        }

        if (sec_login_setup_identity((unsigned char *)user,
                                     sec_login_no_flags,
                                     &my_dce_sec_context,
                                     &err) == 0) {
                dce_error_inq_text(err, dce_errstr, &err2);
                DEBUG(0,("DCE Setup Identity for %s failed: %s\n",
                         user,dce_errstr));
                return(False);
        }

        sec_login_get_pwent(my_dce_sec_context, 
                            (sec_login_passwd_t*)&pw, &err);
        if (err != error_status_ok) {
                dce_error_inq_text(err, dce_errstr, &err2);
                DEBUG(0,("DCE can't get pwent. %s\n", dce_errstr));
                
                return(False);
        }

        sec_login_purge_context(&my_dce_sec_context, &err);
        if (err != error_status_ok) {
                dce_error_inq_text(err, dce_errstr, &err2);
                DEBUG(0,("DCE can't purge context. %s\n", dce_errstr));

                return(False);
        }

        /*
         * NB. I'd like to change these to call something like become_user()
         * instead but currently we don't have a connection
         * context to become the correct user. This is already
         * fairly platform specific code however, so I think
         * this should be ok. I have added code to go
         * back to being root on error though. JRA.
         */
        
        egid = getegid();

        if (set_effective_gid(pw->pw_gid) != 0) {
                DEBUG(0,("Can't set egid to %d (%s)\n", 
                         pw->pw_gid, strerror(errno)));
                return False;
        }

        if (set_effective_uid(pw->pw_uid) != 0) {
                set_effective_gid(egid);
                DEBUG(0,("Can't set euid to %d (%s)\n", 
                         pw->pw_uid, strerror(errno)));
                return False;
        }
 
        if (sec_login_setup_identity((unsigned char *)user,
                                     sec_login_no_flags,
                                     &my_dce_sec_context,
                                     &err) == 0) {
                dce_error_inq_text(err, dce_errstr, &err2);
                DEBUG(0,("DCE Setup Identity for %s failed: %s\n",
                         user,dce_errstr));
                goto err;
        }

        sec_login_get_pwent(my_dce_sec_context, 
                            (sec_login_passwd_t*)&pw, &err);
        if (err != error_status_ok ) {
                dce_error_inq_text(err, dce_errstr, &err2);
                DEBUG(0,("DCE can't get pwent. %s\n", dce_errstr));
                goto err;
        }

        passwd_rec.version_number = sec_passwd_c_version_none;
        passwd_rec.pepper = NULL;
        passwd_rec.key.key_type = sec_passwd_plain;
        passwd_rec.key.tagged_union.plain  = (idl_char *)password;
        
        sec_login_validate_identity(my_dce_sec_context,
                                    &passwd_rec, &password_reset,
                                    &auth_src, &err);
        if (err != error_status_ok ) { 
                dce_error_inq_text(err, dce_errstr, &err2);
                DEBUG(0,("DCE Identity Validation failed for principal %s: %s\n",
                         user,dce_errstr));
                goto err;
        }

        sec_login_certify_identity(my_dce_sec_context, &err);
        if (err != error_status_ok) { 
                dce_error_inq_text(err, dce_errstr, &err2);
                DEBUG(0,("DCE certify identity failed: %s\n", dce_errstr));
                goto err;
        }

        if (auth_src != sec_login_auth_src_network) { 
                DEBUG(0,("DCE context has no network credentials.\n"));
        }

        sec_login_set_context(my_dce_sec_context, &err);
        if (err != error_status_ok) {  
                dce_error_inq_text(err, dce_errstr, &err2);
                DEBUG(0,("DCE login failed for principal %s, cant set context: %s\n",
                         user,dce_errstr));
                
                sec_login_purge_context(&my_dce_sec_context, &err);
                goto err;
        }
        
        sec_login_get_pwent(my_dce_sec_context, 
                            (sec_login_passwd_t*)&pw, &err);
        if (err != error_status_ok) {
                dce_error_inq_text(err, dce_errstr, &err2);
                DEBUG(0,("DCE can't get pwent. %s\n", dce_errstr));
                goto err;
        }
        
        DEBUG(0,("DCE login succeeded for principal %s on pid %d\n",
                 user, getpid()));
        
        DEBUG(3,("DCE principal: %s\n"
                 "          uid: %d\n"
                 "          gid: %d\n",
                 pw->pw_name, pw->pw_uid, pw->pw_gid));
        DEBUG(3,("         info: %s\n"
                 "          dir: %s\n"
                 "        shell: %s\n",
                 pw->pw_gecos, pw->pw_dir, pw->pw_shell));
        
        sec_login_get_expiration(my_dce_sec_context, &expire_time, &err);
        if (err != error_status_ok) {
                dce_error_inq_text(err, dce_errstr, &err2);
                DEBUG(0,("DCE can't get expiration. %s\n", dce_errstr));
                goto err;
        }
        
        set_effective_uid(0);
        set_effective_gid(0);
        
        DEBUG(0,("DCE context expires: %s",asctime(localtime(&expire_time))));
        
        dcelogin_atmost_once = 1;
        return (True);

err:

        /* Go back to root, JRA. */
        set_effective_uid(0);
        set_effective_gid(egid);
        return(False);
}

void dfs_unlogin(void)
{
        error_status_t err;
        int err2;
        unsigned char dce_errstr[dce_c_error_string_len];
        
        sec_login_purge_context(&my_dce_sec_context, &err);
        if (err != error_status_ok) {  
                dce_error_inq_text(err, dce_errstr, &err2);
                DEBUG(0,("DCE purge login context failed for server instance %d: %s\n",
                         getpid(), dce_errstr));
        }
}
#endif

#ifdef KRB5_AUTH

#include <krb5.h>

/*******************************************************************
check on Kerberos authentication
********************************************************************/
static BOOL krb5_auth(char *user,char *password)
{
        krb5_data tgtname = {
                0,
                KRB5_TGS_NAME_SIZE,
                KRB5_TGS_NAME
        };
        krb5_context kcontext;
        krb5_principal kprinc;
        krb5_principal server;
        krb5_creds kcreds;
        int options = 0;
        krb5_address **addrs = (krb5_address **)0;
        krb5_preauthtype *preauth = NULL;
        krb5_keytab keytab = NULL;
        krb5_timestamp now;
        krb5_ccache ccache = NULL;
        int retval;
        char *name;

        if (retval=krb5_init_context(&kcontext)) {
                return(False);
        }

        if (retval = krb5_timeofday(kcontext, &now)) {
                return(False);
        }

        if (retval = krb5_cc_default(kcontext, &ccache)) {
                return(False);
        }
        
        if (retval = krb5_parse_name(kcontext, user, &kprinc)) {
                return(False);
        }

        ZERO_STRUCT(kcreds);

        kcreds.client = kprinc;
        
        if ((retval = krb5_build_principal_ext(kcontext, &server,
                krb5_princ_realm(kcontext, kprinc)->length,
                krb5_princ_realm(kcontext, kprinc)->data,
                tgtname.length,
                tgtname.data,
                krb5_princ_realm(kcontext, kprinc)->length,
                krb5_princ_realm(kcontext, kprinc)->data,
                0))) {
                return(False);
        }

        kcreds.server = server;

        retval = krb5_get_in_tkt_with_password(kcontext,
                                               options,
                                               addrs,
                                               NULL,
                                               preauth,
                                               password,
                                               0,
                                               &kcreds,
                                               0);

        if (retval) {
                return(False);
        }

        return(True);
}
#endif /* KRB5_AUTH */

#ifdef KRB4_AUTH
#include <krb.h>

/*******************************************************************
check on Kerberos authentication
********************************************************************/
static BOOL krb4_auth(char *user,char *password)
{
        char realm[REALM_SZ];
        char tkfile[MAXPATHLEN];
  
        if (krb_get_lrealm(realm, 1) != KSUCCESS) {
                (void) safe_strcpy(realm, KRB_REALM, sizeof (realm) - 1);
        }

        (void) slprintf(tkfile, sizeof(tkfile) - 1, "/tmp/samba_tkt_%d", 
                        (int)getpid());
  
        krb_set_tkt_string(tkfile);
        if (krb_verify_user(user, "", realm,
                            password, 0,
                            "rmcd") == KSUCCESS) {
                unlink(tkfile);
                return 1;
        }
        unlink(tkfile);
        return 0;
}
#endif /* KRB4_AUTH */

#ifdef LINUX_BIGCRYPT
/****************************************************************************
an enhanced crypt for Linux to handle password longer than 8 characters
****************************************************************************/
static int linux_bigcrypt(char *password,char *salt1, char *crypted)
{
#define LINUX_PASSWORD_SEG_CHARS 8
        char salt[3];
        int i;
  
        StrnCpy(salt,salt1,2);
        crypted +=2;
  
        for ( i=strlen(password); i > 0; i -= LINUX_PASSWORD_SEG_CHARS) {
                char * p = crypt(password,salt) + 2;
                if (strncmp(p, crypted, LINUX_PASSWORD_SEG_CHARS) != 0)
                        return(0);
                password += LINUX_PASSWORD_SEG_CHARS;
                crypted  += strlen(p);
        }
  
        return(1);
}
#endif

#ifdef OSF1_ENH_SEC
/****************************************************************************
an enhanced crypt for OSF1
****************************************************************************/
static char *osf1_bigcrypt(char *password,char *salt1)
{
        static char result[AUTH_MAX_PASSWD_LENGTH] = "";
        char *p1;
        char *p2=password;
        char salt[3];
        int i;
        int parts = strlen(password) / AUTH_CLEARTEXT_SEG_CHARS;
        if (strlen(password)%AUTH_CLEARTEXT_SEG_CHARS) {
                parts++;
        }
        
        StrnCpy(salt,salt1,2);
        StrnCpy(result,salt1,2);
        result[2]='\0';

        for (i=0; i<parts;i++) {
                p1 = crypt(p2,salt);
                strncat(result,p1+2,AUTH_MAX_PASSWD_LENGTH-strlen(p1+2)-1);
                StrnCpy(salt,&result[2+i*AUTH_CIPHERTEXT_SEG_CHARS],2);
                p2 += AUTH_CLEARTEXT_SEG_CHARS;
        }

        return(result);
}
#endif


/****************************************************************************
apply a function to upper/lower case combinations
of a string and return true if one of them returns true.
try all combinations with N uppercase letters.
offset is the first char to try and change (start with 0)
it assumes the string starts lowercased
****************************************************************************/
static BOOL string_combinations2(char *s,int offset,BOOL (*fn)(char *),int N)
{
        int len = strlen(s);
        int i;

#ifdef PASSWORD_LENGTH
        len = MIN(len,PASSWORD_LENGTH);
#endif

        if (N <= 0 || offset >= len) {
                return(fn(s));
        }

        for (i=offset;i<(len-(N-1));i++) {      
                char c = s[i];
                if (!islower(c)) continue;
                s[i] = toupper(c);
                if (string_combinations2(s,i+1,fn,N-1))
                        return(True);
                s[i] = c;
        }
        return(False);
}

/****************************************************************************
apply a function to upper/lower case combinations
of a string and return true if one of them returns true.
try all combinations with up to N uppercase letters.
offset is the first char to try and change (start with 0)
it assumes the string starts lowercased
****************************************************************************/
static BOOL string_combinations(char *s,BOOL (*fn)(char *),int N)
{
        int n;
        for (n=1;n<=N;n++)
                if (string_combinations2(s,0,fn,n)) return(True);
        return(False);
}


/****************************************************************************
core of password checking routine
****************************************************************************/
static BOOL password_check(char *password)
{

#ifdef WITH_PAM
        /* This falls through if the password check fails
           - if HAVE_CRYPT is not defined this causes an error msg
           saying Warning - no crypt available
           - if HAVE_CRYPT is defined this is a potential security hole
           as it may authenticate via the crypt call when PAM
           settings say it should fail.
           if (pam_auth(user,password)) return(True);
           Hence we make a direct return to avoid a second chance!!!
        */
        return (pam_auth(this_user,password));
#endif /* WITH_PAM */
        
#ifdef WITH_AFS
        if (afs_auth(this_user,password)) return(True);
#endif /* WITH_AFS */
        
#ifdef WITH_DFS
        if (dfs_auth(this_user,password)) return(True);
#endif /* WITH_DFS */

#ifdef KRB5_AUTH
        if (krb5_auth(this_user,password)) return(True);
#endif /* KRB5_AUTH */

#ifdef KRB4_AUTH
        if (krb4_auth(this_user,password)) return(True);
#endif /* KRB4_AUTH */

#ifdef OSF1_ENH_SEC
        {
          BOOL ret = (strcmp(osf1_bigcrypt(password,this_salt),this_crypted) == 0);
          if(!ret) {
                  DEBUG(2,("OSF1_ENH_SEC failed. Trying normal crypt.\n"));
                  ret = (strcmp((char *)crypt(password,this_salt),this_crypted) == 0);
          }
          return ret;
        }
#endif /* OSF1_ENH_SEC */

#ifdef ULTRIX_AUTH
        return (strcmp((char *)crypt16(password, this_salt ),this_crypted) == 0);
#endif /* ULTRIX_AUTH */

#ifdef LINUX_BIGCRYPT
        return(linux_bigcrypt(password,this_salt,this_crypted));
#endif /* LINUX_BIGCRYPT */

#if defined(HAVE_BIGCRYPT) && defined(HAVE_CRYPT) && defined(USE_BOTH_CRYPT_CALLS)

        /*
         * Some systems have bigcrypt in the C library but might not
         * actually use it for the password hashes (HPUX 10.20) is
         * a noteable example. So we try bigcrypt first, followed
         * by crypt.
         */

        if(strcmp(bigcrypt(password,this_salt),this_crypted) == 0)
                return True;
        else 
                return (strcmp((char *)crypt(password,this_salt),this_crypted) == 0);
#else /* HAVE_BIGCRYPT && HAVE_CRYPT && USE_BOTH_CRYPT_CALLS */

#ifdef HAVE_BIGCRYPT
        return(strcmp(bigcrypt(password,this_salt),this_crypted) == 0);
#endif /* HAVE_BIGCRYPT */

#ifndef HAVE_CRYPT
        DEBUG(1,("Warning - no crypt available\n"));
        return(False);
#else /* HAVE_CRYPT */
        return(strcmp((char *)crypt(password,this_salt),this_crypted) == 0);
#endif /* HAVE_CRYPT */
#endif /* HAVE_BIGCRYPT && HAVE_CRYPT && USE_BOTH_CRYPT_CALLS */
}



/****************************************************************************
check if a username/password is OK
the function pointer fn() points to a function to call when a successful
match is found and is used to update the encrypted password file 
return True on correct match, False otherwise
****************************************************************************/
BOOL pass_check(char *user,char *password, int pwlen, struct passwd *pwd,
                BOOL (*fn)(char *, char *))
{
        pstring pass2;
        int level = lp_passwordlevel();
        struct passwd *pass;

        if (password) password[pwlen] = 0;

#if DEBUG_PASSWORD
        DEBUG(100,("checking user=[%s] pass=[%s]\n",user,password));
#endif

        if (!password) {
                return(False);
        }

        if (((!*password) || (!pwlen)) && !lp_null_passwords()) {
                return(False);
        }

        if (pwd && !user) {
                pass = (struct passwd *) pwd;
                user = pass->pw_name;
        } else {
                pass = Get_Pwnam(user,True);
        }


        DEBUG(4,("Checking password for user %s (l=%d)\n",user,pwlen));

        if (!pass) {
                DEBUG(3,("Couldn't find user %s\n",user));
                return(False);
        }

#ifdef HAVE_GETSPNAM
        {
                struct spwd *spass;

                /* many shadow systems require you to be root to get
                   the password, in most cases this should already be
                   the case when this function is called, except
                   perhaps for IPC password changing requests */

                spass = getspnam(pass->pw_name);
                if (spass && spass->sp_pwdp) {
                        pstrcpy(pass->pw_passwd,spass->sp_pwdp);
                }
        }
#elif defined(IA_UINFO)
        {
                /* Need to get password with SVR4.2's ia_ functions
                   instead of get{sp,pw}ent functions. Required by
                   UnixWare 2.x, tested on version
                   2.1. (tangent@cyberport.com) */
                uinfo_t uinfo;
                if (ia_openinfo(pass->pw_name, &uinfo) != -1) {
                        ia_get_logpwd(uinfo, &(pass->pw_passwd));
                }
        }
#endif

#ifdef HAVE_GETPRPWNAM
        {
                struct pr_passwd *pr_pw = getprpwnam(pass->pw_name);
                if (pr_pw && pr_pw->ufld.fd_encrypt)
                        pstrcpy(pass->pw_passwd,pr_pw->ufld.fd_encrypt);
        }
#endif

#ifdef OSF1_ENH_SEC
        {
                struct pr_passwd *mypasswd;
                DEBUG(5,("Checking password for user %s in OSF1_ENH_SEC\n",
                         user));
                mypasswd = getprpwnam (user);
                if (mypasswd) { 
                        fstrcpy(pass->pw_name,mypasswd->ufld.fd_name);
                        fstrcpy(pass->pw_passwd,mypasswd->ufld.fd_encrypt);
                } else {
                        DEBUG(5,("OSF1_ENH_SEC: No entry for user %s in protected database !\n",
                                 user));
                }
        }
#endif

#ifdef ULTRIX_AUTH
        {
                AUTHORIZATION *ap = getauthuid(pass->pw_uid);
                if (ap) {
                        fstrcpy(pass->pw_passwd, ap->a_password);
                        endauthent();
                }
        }
#endif

        /* extract relevant info */
        fstrcpy(this_user,pass->pw_name);  
        fstrcpy(this_salt,pass->pw_passwd);

#if defined(HAVE_TRUNCATED_SALT)
        /* crypt on some platforms (HPUX in particular)
           won't work with more than 2 salt characters. */
        this_salt[2] = 0;
#endif
        
        fstrcpy(this_crypted,pass->pw_passwd);
        
        if (!*this_crypted) {
                if (!lp_null_passwords()) {
                        DEBUG(2,("Disallowing %s with null password\n",
                                 this_user));
                        return(False);
                }
                if (!*password) {
                        DEBUG(3,("Allowing access to %s with null password\n",
                                 this_user));
                        return(True);
                }
        }

        /* try it as it came to us */
        if (password_check(password)) {
                if (fn) fn(user,password);
                return(True);
        }

        /* if the password was given to us with mixed case then we don't
           need to proceed as we know it hasn't been case modified by the
           client */
        if (strhasupper(password) && strhaslower(password)) {
                return(False);
        }

        /* make a copy of it */
        StrnCpy(pass2,password,sizeof(pstring)-1);
  
        /* try all lowercase */
        strlower(password);
        if (password_check(password)) {
                if (fn) fn(user,password);
                return(True);
        }

        /* give up? */
        if (level < 1) {

                /* restore it */
                fstrcpy(password,pass2);
                
                return(False);
        }

        /* last chance - all combinations of up to level chars upper! */
        strlower(password);

        if (string_combinations(password,password_check,level)) {
                if (fn) fn(user,password);
                return(True);
        }

        /* restore it */
        fstrcpy(password,pass2);
  
        return(False);
}