util.c revision 1.27 
1/*	$OpenBSD: util.c,v 1.27 2013/11/13 05:41:42 deraadt Exp $	*/
2
3/*
4 * Copyright (c) 1998 Per Fogelstrom, Opsycon AB
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
16 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
19 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 */
28
29#include <sys/types.h>
30#include <sys/param.h>
31#include <sys/mman.h>
32#include <sys/sysctl.h>
33#include <string.h>
34#include "archdep.h"
35
36/*
37 * Stack protector dummies.
38 * Ideally, a scheme to compile these stubs from libc should be used, but
39 * this would end up dragging too much code from libc here.
40 */
41long __guard[8] __dso_public __attribute__((section(".openbsd.randomdata")));
42long __guard_local __dso_hidden __attribute__((section(".openbsd.randomdata")));
43
44void __stack_smash_handler(char [], int);
45
46void
47__stack_smash_handler(char func[], int damaged)
48{
49	_dl_exit(127);
50}
51
52/*
53 * Static vars usable after bootstrapping.
54 */
55static char *_dl_malloc_pool;
56static long *_dl_malloc_free;
57
58char *
59_dl_strdup(const char *orig)
60{
61	char *newstr;
62	int len;
63
64	len = _dl_strlen(orig)+1;
65	newstr = _dl_malloc(len);
66	_dl_strlcpy(newstr, orig, len);
67	return (newstr);
68}
69
70
71/*
72 * The following malloc/free code is a very simplified implementation
73 * of a malloc function. However, we do not need to be very complex here
74 * because we only free memory when 'dlclose()' is called and we can
75 * reuse at least the memory allocated for the object descriptor. We have
76 * one dynamic string allocated, the library name and it is likely that
77 * we can reuse that one too without a lot of complex collapsing code.
78 */
79void *
80_dl_malloc(size_t need)
81{
82	long *p, *t, *n, have;
83
84	need = (need + 2*DL_MALLOC_ALIGN - 1) & ~(DL_MALLOC_ALIGN - 1);
85
86	if ((t = _dl_malloc_free) != 0) {	/* Try free list first */
87		n = (long *)&_dl_malloc_free;
88		while (t && t[-1] < need) {
89			n = t;
90			t = (long *)*t;
91		}
92		if (t) {
93			*n = *t;
94			_dl_memset(t, 0, t[-1] - DL_MALLOC_ALIGN);
95			return((void *)t);
96		}
97	}
98	have = _dl_round_page((long)_dl_malloc_pool) - (long)_dl_malloc_pool;
99	if (need > have) {
100		if (have >= 8 + DL_MALLOC_ALIGN) {
101			p = (void *)_dl_malloc_pool;
102			p = (void *) ((long)p + DL_MALLOC_ALIGN);
103			p[-1] = have;
104			_dl_free((void *)p);		/* move to freelist */
105		}
106		_dl_malloc_pool = (void *)_dl_mmap((void *)0,
107		    _dl_round_page(need), PROT_READ|PROT_WRITE,
108		    MAP_ANON|MAP_PRIVATE, -1, 0);
109		if (_dl_malloc_pool == 0 || _dl_mmap_error(_dl_malloc_pool)) {
110			_dl_printf("Dynamic loader failure: malloc.\n");
111			_dl_exit(7);
112		}
113	}
114	p = (void *)_dl_malloc_pool;
115	_dl_malloc_pool += need;
116	_dl_memset(p, 0, need);
117	p = (void *) ((long)p + DL_MALLOC_ALIGN);
118	p[-1] = need;
119	return (p);
120}
121
122void
123_dl_free(void *p)
124{
125	long *t = (long *)p;
126
127	*t = (long)_dl_malloc_free;
128	_dl_malloc_free = p;
129}
130
131
132void
133_dl_randombuf(void *buf, size_t buflen)
134{
135	const int mib[2] = { CTL_KERN, KERN_ARND };
136	_dl_sysctl(mib, 2, buf, &buflen, NULL, 0);
137}
138
139unsigned int
140_dl_random(void)
141{
142	unsigned int rnd;
143	_dl_randombuf(&rnd, sizeof(rnd));
144	return (rnd);
145}
146