tests/overflowuid.c

/*
 * Copyright (c) 2014-2016 Dmitry V. Levin <ldv@altlinux.org>
 * 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 BY THE AUTHOR ``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 "tests.h"
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>

static void
check_overflow_id(const int id, const char *overflowid)
{
	int fd = open(overflowid, O_RDONLY);
	if (fd < 0) {
		if (ENOENT == errno)
			return;
		perror_msg_and_fail("open: %s", overflowid);
	}

	/* we trust the kernel */
	char buf[sizeof(int)*3];
	int n = read(fd, buf, sizeof(buf) - 1);
	if (n > 0) {
		buf[n] = '\0';
		n = atoi(buf);
		if (id == n)
			error_msg_and_skip("%d matches %s", id, overflowid);
	}

	close(fd);
}

void
check_overflowuid(const int uid)
{
	check_overflow_id(uid, "/proc/sys/kernel/overflowuid");
}

void
check_overflowgid(const int gid)
{
	check_overflow_id(gid, "/proc/sys/kernel/overflowgid");
}