1/*	$OpenBSD: isexec.c,v 1.13 2021/10/24 21:24:17 deraadt Exp $	*/
2
3/*
4 * Copyright (c) 1983 Regents of the University of California.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/types.h>
33#include <elf.h>
34#include <fcntl.h>
35#include <unistd.h>
36
37#include "client.h"
38
39/*
40 * Determine whether 'file' is a binary executable or not.
41 */
42int
43isexec(char *file, struct stat *statp)
44{
45	Elf32_Ehdr hdr;
46	int fd, r;
47
48	/*
49	 * Must be a regular file that has some executable mode bit on
50	 */
51	if (!S_ISREG(statp->st_mode) ||
52	    !(statp->st_mode & (S_IXUSR|S_IXGRP|S_IXOTH)))
53		return(FALSE);
54
55	if ((fd = open(file, O_RDONLY)) == -1)
56		return(FALSE);
57
58	r = read(fd, &hdr, sizeof(hdr)) == sizeof(hdr) &&
59	    IS_ELF(hdr) && hdr.e_type == ET_EXEC;
60	close(fd);
61
62	return (r);
63}
64