1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
|
/* $OpenBSD: arc4random.c,v 1.54 2015/09/13 08:31:47 guenther Exp $ */
/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 1996, David Mazieres <dm@uun.org>
* Copyright (c) 2008, Damien Miller <djm@openbsd.org>
* Copyright (c) 2013, Markus Friedl <markus@openbsd.org>
* Copyright (c) 2014, Theo de Raadt <deraadt@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* This is an open source non-commercial project. Dear PVS-Studio, please check it.
* PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
*/
/*
* ChaCha based random number generator for OpenBSD.
*/
#include <config.h>
#ifndef HAVE_ARC4RANDOM
#ifdef HAVE_SYS_RANDOM_H
# include <sys/random.h>
#endif
#include <fcntl.h>
#include <limits.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#if defined(HAVE_STDINT_H)
# include <stdint.h>
#elif defined(HAVE_INTTYPES_H)
# include <inttypes.h>
#endif
#include "sudo_compat.h"
#include "sudo_fatal.h"
#include "sudo_rand.h"
#define KEYSTREAM_ONLY
#include "chacha_private.h"
#define minimum(a, b) ((a) < (b) ? (a) : (b))
#ifdef __GNUC__
# define inline __inline
#else /* !__GNUC__ */
# define inline
#endif /* !__GNUC__ */
/* Sudo isn't multithreaded */
#define _ARC4_LOCK()
#define _ARC4_UNLOCK()
#define KEYSZ 32
#define IVSZ 8
#define BLOCKSZ 64
#define RSBUFSZ (16*BLOCKSZ)
static int rs_initialized;
static pid_t rs_stir_pid;
static chacha_ctx rs; /* chacha context for random keystream */
static u_char rs_buf[RSBUFSZ]; /* keystream blocks */
static size_t rs_have; /* valid bytes at end of rs_buf */
static size_t rs_count; /* bytes till reseed */
static inline void _rs_rekey(unsigned char *dat, size_t datlen);
static inline void
_rs_init(unsigned char *buf, size_t n)
{
if (n < KEYSZ + IVSZ)
return;
chacha_keysetup(&rs, buf, KEYSZ * 8, 0);
chacha_ivsetup(&rs, buf + KEYSZ);
}
static void
_rs_stir(void)
{
unsigned char rnd[KEYSZ + IVSZ];
if (getentropy(rnd, sizeof rnd) == -1)
sudo_fatal_nodebug("getentropy");
if (!rs_initialized) {
rs_initialized = 1;
_rs_init(rnd, sizeof(rnd));
} else
_rs_rekey(rnd, sizeof(rnd));
explicit_bzero(rnd, sizeof(rnd)); /* discard source seed */
/* invalidate rs_buf */
rs_have = 0;
memset(rs_buf, 0, sizeof(rs_buf));
rs_count = 1600000;
}
static inline void
_rs_stir_if_needed(size_t len)
{
pid_t pid = getpid();
if (rs_count <= len || !rs_initialized || rs_stir_pid != pid) {
rs_stir_pid = pid;
_rs_stir();
} else
rs_count -= len;
}
static inline void
_rs_rekey(unsigned char *dat, size_t datlen)
{
#ifndef KEYSTREAM_ONLY
memset(rs_buf, 0, sizeof(rs_buf));
#endif
/* fill rs_buf with the keystream */
chacha_encrypt_bytes(&rs, rs_buf, rs_buf, sizeof(rs_buf));
/* mix in optional user provided data */
if (dat) {
size_t i, m;
m = minimum(datlen, KEYSZ + IVSZ);
for (i = 0; i < m; i++)
rs_buf[i] ^= dat[i];
}
/* immediately reinit for backtracking resistance */
_rs_init(rs_buf, KEYSZ + IVSZ);
memset(rs_buf, 0, KEYSZ + IVSZ); // -V::512, 1086
rs_have = sizeof(rs_buf) - KEYSZ - IVSZ;
}
static inline void
_rs_random_buf(void *_buf, size_t n)
{
unsigned char *buf = _buf;
unsigned char *keystream;
size_t m;
_rs_stir_if_needed(n);
while (n > 0) {
if (rs_have > 0) {
m = minimum(n, rs_have);
keystream = rs_buf + sizeof(rs_buf) - rs_have;
memcpy(buf, keystream, m);
memset(keystream, 0, m);
buf += m;
n -= m;
rs_have -= m;
}
if (rs_have == 0)
_rs_rekey(NULL, 0);
}
}
static inline void
_rs_random_u32(uint32_t *val)
{
unsigned char *keystream;
_rs_stir_if_needed(sizeof(*val));
if (rs_have < sizeof(*val))
_rs_rekey(NULL, 0);
keystream = rs_buf + sizeof(rs_buf) - rs_have;
memcpy(val, keystream, sizeof(*val));
memset(keystream, 0, sizeof(*val));
rs_have -= sizeof(*val);
}
uint32_t
sudo_arc4random(void)
{
uint32_t val;
_ARC4_LOCK();
_rs_random_u32(&val);
_ARC4_UNLOCK();
return val;
}
void
sudo_arc4random_buf(void *buf, size_t n)
{
_ARC4_LOCK();
_rs_random_buf(buf, n);
_ARC4_UNLOCK();
}
#endif /* HAVE_ARC4RANDOM */
|
