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
48 SSP_STATIC long stack_chk_guard[8] = {0, 0, 0, 0, 0, 0, 0, 0,};
49 SSP_STATIC void stack_chk_fail(void);
50
51 SSP_STATIC void
stack_chk_fail(void)52 stack_chk_fail(void)
53 {
54 panic("stack overflow detected; terminated");
55 }
56
57 void
ssp_init(void)58 ssp_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
81 void
ssp_init(void)82 ssp_init(void)
83 {
84 }
85 #endif
86