209 lines
6.0 KiB
C
209 lines
6.0 KiB
C
/*
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* $Id: pwdb_chkpwd.c,v 1.1 1997/02/15 17:26:18 morgan Exp $
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*
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* This program is designed to run setuid(root) or with sufficient
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* privilege to read all of the unix password databases. It is designed
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* to provide a mechanism for the current user (defined by this
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* process' real uid) to verify their own password.
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*
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* The password is read from the standard input. The exit status of
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* this program indicates whether the user is authenticated or not.
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*
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* Copyright information is located at the end of the file.
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*
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* $Log: pwdb_chkpwd.c,v $
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* Revision 1.1 1997/02/15 17:26:18 morgan
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* Initial revision
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*
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* Revision 1.1 1996/11/10 21:20:51 morgan
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* Initial revision
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*
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*/
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#ifdef linux
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# define _GNU_SOURCE
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# include <features.h>
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#endif
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <syslog.h>
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#include <unistd.h>
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#include <security/_pam_macros.h>
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#define MAXPASS 200 /* the maximum length of a password */
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#define UNIX_PASSED (PWDB_SUCCESS)
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#define UNIX_FAILED (PWDB_SUCCESS+1)
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#include <pwdb/pwdb_public.h>
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/* syslogging function for errors and other information */
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static void _log_err(int err, const char *format, ...)
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{
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va_list args;
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va_start(args, format);
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openlog("pwdb_chkpwd", LOG_CONS|LOG_PID, LOG_AUTH);
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vsyslog(err, format, args);
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va_end(args);
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closelog();
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}
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#include "pam_unix_md.-c"
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static int _unix_verify_passwd(const char *salt, const char *p)
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{
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char *pp=NULL;
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int retval;
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if (p == NULL) {
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if (*salt == '\0') {
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retval = UNIX_PASSED;
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} else {
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retval = UNIX_FAILED;
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}
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} else {
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pp = _pam_md(p, salt);
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p = NULL; /* no longer needed here */
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if ( strcmp( pp, salt ) == 0 ) {
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retval = UNIX_PASSED;
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} else {
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retval = UNIX_FAILED;
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}
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}
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/* clean up */
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{
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char *tp = pp;
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if (pp != NULL) {
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while(tp && *tp)
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*tp++ = '\0';
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free(pp);
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pp = tp = NULL;
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}
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}
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return retval;
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}
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void main(void)
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{
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const struct pwdb *pw=NULL;
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const struct pwdb_entry *pwe=NULL;
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char pass[MAXPASS+1];
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int npass;
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int retval=UNIX_FAILED;
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/*
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* we establish that this program is running with non-tty stdin.
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* this is to discourage casual use. It does *NOT* prevent an
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* intruder from repeatadly running this program to determine the
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* password of the current user (brute force attack, but one for
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* which the attacker must already have gained access to the user's
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* account).
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*/
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if ( isatty(STDIN_FILENO) ) {
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_log_err(LOG_NOTICE
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, "inappropriate use of PWDB helper binary [UID=%d]"
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, getuid() );
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fprintf(stderr,
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"This program is not designed for running in this way\n"
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"-- the system administrator has been informed\n");
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exit(UNIX_FAILED);
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}
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/*
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* determine the current user's name:
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*/
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retval = pwdb_start();
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if (retval != PWDB_SUCCESS) {
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_log_err(LOG_ALERT, "failed to open pwdb");
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retval = UNIX_FAILED;
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}
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if (retval != UNIX_FAILED) {
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retval = pwdb_locate("user", PWDB_DEFAULT, PWDB_NAME_UNKNOWN
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, getuid(), &pw);
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}
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if (retval != PWDB_SUCCESS) {
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_log_err(LOG_ALERT, "could not identify user");
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while (pwdb_end() != PWDB_SUCCESS);
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exit(UNIX_FAILED);
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}
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/* read the password from stdin (a pipe from the pam_pwdb module) */
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npass = read(STDIN_FILENO, pass, MAXPASS);
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if (npass < 0) { /* is it a valid password? */
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_log_err(LOG_DEBUG, "no password supplied");
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retval = UNIX_FAILED;
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} else if (npass >= MAXPASS-1) {
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_log_err(LOG_DEBUG, "password too long");
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retval = UNIX_FAILED;
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} else if (pwdb_get_entry(pw, "passwd", &pwe) != PWDB_SUCCESS) {
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_log_err(LOG_WARNING, "password not found");
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retval = UNIX_FAILED;
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} else {
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if (npass <= 0) {
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/* the password is NULL */
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retval = _unix_verify_passwd((const char *)(pwe->value), NULL);
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} else {
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/* does pass agree with the official one? */
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pass[npass] = '\0'; /* NUL terminate */
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retval = _unix_verify_passwd((const char *)(pwe->value), pass);
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}
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}
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memset(pass, '\0', MAXPASS); /* clear memory of the password */
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while (pwdb_end() != PWDB_SUCCESS);
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/* return pass or fail */
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exit(retval);
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}
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/*
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* Copyright (c) Andrew G. Morgan, 1997. All rights reserved
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, and the entire permission notice in its entirety,
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* including the disclaimer of warranties.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior
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* written permission.
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*
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* ALTERNATIVELY, this product may be distributed under the terms of
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* the GNU Public License, in which case the provisions of the GPL are
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* required INSTEAD OF the above restrictions. (This clause is
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* necessary due to a potential bad interaction between the GPL and
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* the restrictions contained in a BSD-style copyright.)
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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