1/*	$NetBSD: kern_ssp.c,v 1.7 2016/12/06 02:55:42 christos Exp $	*/
2
3/*-
4 * Copyright (c) 2008 The NetBSD Foundation, Inc.
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 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__KERNEL_RCSID(0, "$NetBSD: kern_ssp.c,v 1.7 2016/12/06 02:55:42 christos Exp $");
31
32#include <sys/param.h>
33#include <sys/systm.h>
34#include <sys/intr.h>
35#include <sys/cprng.h>
36
37#if defined(__SSP__) || defined(__SSP_ALL__)
38# ifdef _RUMPKERNEL
39__weak_alias(__stack_chk_guard, stack_chk_guard)
40__weak_alias(__stack_chk_fail, stack_chk_fail)
41# define SSP_STATIC static __used
42# else
43# define stack_chk_guard __stack_chk_guard
44# define stack_chk_fail __stack_chk_fail
45# define SSP_STATIC
46#endif
47
48SSP_STATIC long stack_chk_guard[8] = {0, 0, 0, 0, 0, 0, 0, 0,};
49SSP_STATIC void stack_chk_fail(void);
50
51SSP_STATIC void
52stack_chk_fail(void)
53{
54	panic("stack overflow detected; terminated");
55}
56
57void
58ssp_init(void)
59{
60	int s;
61
62	aprint_debug("Initializing SSP: ");
63	/*
64	 * We initialize ssp here carefully:
65	 *	1. after we got some entropy
66	 *	2. without calling a function
67	 */
68	size_t i;
69	long guard[__arraycount(stack_chk_guard)];
70
71	cprng_fast(guard, sizeof(guard));
72	s = splhigh();
73	for (i = 0; i < __arraycount(guard); i++)
74		stack_chk_guard[i] = guard[i];
75	splx(s);
76	for (i = 0; i < __arraycount(guard); i++)
77		aprint_debug("%lx ", guard[i]);
78	aprint_debug("\n");
79}
80#else
81void
82ssp_init(void)
83{
84}
85#endif
86