sudo/goodpath.c

/*
 * Copyright (c) 1996, 1998, 1999 Todd C. Miller <Todd.Miller@courtesan.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"

#include <stdio.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif /* HAVE_UNISTD_H */
#ifdef HAVE_STRING_H
#include <string.h>
#endif /* HAVE_STRING_H */
#ifdef HAVE_STRINGS_H
#include <strings.h>
#endif /* HAVE_STRINGS_H */
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>

#include "sudo.h"

#ifndef STDC_HEADERS
extern int stat		__P((const char *, struct stat *));
#endif /* !STDC_HEADERS */

#ifndef lint
static const char rcsid[] = "$Sudo$";
#endif /* lint */

/*
 * Verify that path is a normal file and executable by root.
 */
char *
sudo_goodpath(path)
    const char *path;
{
    struct stat sb;
    int err;

    /* Check for brain damage */
    if (path == NULL || path[0] == '\0')
	return(NULL);

    /* Do the stat() as root. */
    set_perms(PERM_ROOT, 0);
    err = stat(path, &sb);
    set_perms(PERM_USER, 0);

    /* stat() failed */
    if (err)
	return(NULL);

    /* Make sure path describes an executable regular file. */
    if (!S_ISREG(sb.st_mode) || !(sb.st_mode & 0000111)) {
	errno = EACCES;
	return(NULL);
    }

    return((char *)path);
}