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
207
208
209
210
211
212
213
214
215
216
217
218
219
|
/* Copyright (c) 2014, Google Inc.
*
* Permission to use, copy, modify, and/or 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. */
#include <openssl/rand.h>
#if !defined(OPENSSL_WINDOWS)
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <openssl/thread.h>
#include <openssl/mem.h>
#include "internal.h"
#include "../internal.h"
/* This file implements a PRNG by reading from /dev/urandom, optionally with a
* buffer, which is unsafe across |fork|. */
#define BUF_SIZE 4096
/* rand_buffer contains unused, random bytes, some of which may have been
* consumed already. */
struct rand_buffer {
size_t used;
uint8_t rand[BUF_SIZE];
};
/* requested_lock is used to protect the |*_requested| variables. */
static struct CRYPTO_STATIC_MUTEX requested_lock = CRYPTO_STATIC_MUTEX_INIT;
/* urandom_fd_requested is set by |RAND_set_urandom_fd|. It's protected by
* |requested_lock|. */
static int urandom_fd_requested = -2;
/* urandom_fd is a file descriptor to /dev/urandom. It's protected by |once|. */
static int urandom_fd = -2;
/* urandom_buffering_requested is set by |RAND_enable_fork_unsafe_buffering|.
* It's protected by |requested_lock|. */
static int urandom_buffering_requested = 0;
/* urandom_buffering controls whether buffering is enabled (1) or not (0). This
* is protected by |once|. */
static int urandom_buffering = 0;
static CRYPTO_once_t once = CRYPTO_ONCE_INIT;
/* init_once initializes the state of this module to values previously
* requested. This is the only function that modifies |urandom_fd| and
* |urandom_buffering|, whose values may be read safely after calling the
* once. */
static void init_once(void) {
CRYPTO_STATIC_MUTEX_lock_read(&requested_lock);
urandom_buffering = urandom_buffering_requested;
int fd = urandom_fd_requested;
CRYPTO_STATIC_MUTEX_unlock(&requested_lock);
if (fd == -2) {
do {
fd = open("/dev/urandom", O_RDONLY);
} while (fd == -1 && errno == EINTR);
}
if (fd < 0) {
abort();
}
int flags = fcntl(fd, F_GETFD);
if (flags == -1) {
abort();
}
flags |= FD_CLOEXEC;
if (fcntl(fd, F_SETFD, flags) == -1) {
abort();
}
urandom_fd = fd;
}
void RAND_cleanup(void) {}
void RAND_set_urandom_fd(int fd) {
fd = dup(fd);
if (fd < 0) {
abort();
}
CRYPTO_STATIC_MUTEX_lock_write(&requested_lock);
urandom_fd_requested = fd;
CRYPTO_STATIC_MUTEX_unlock(&requested_lock);
CRYPTO_once(&once, init_once);
if (urandom_fd != fd) {
abort(); // Already initialized.
}
}
void RAND_enable_fork_unsafe_buffering(int fd) {
if (fd >= 0) {
fd = dup(fd);
if (fd < 0) {
abort();
}
} else {
fd = -2;
}
CRYPTO_STATIC_MUTEX_lock_write(&requested_lock);
urandom_buffering_requested = 1;
urandom_fd_requested = fd;
CRYPTO_STATIC_MUTEX_unlock(&requested_lock);
CRYPTO_once(&once, init_once);
if (urandom_buffering != 1 || (fd >= 0 && urandom_fd != fd)) {
abort(); // Already initialized.
}
}
static struct rand_buffer *get_thread_local_buffer(void) {
struct rand_buffer *buf =
CRYPTO_get_thread_local(OPENSSL_THREAD_LOCAL_URANDOM_BUF);
if (buf != NULL) {
return buf;
}
buf = OPENSSL_malloc(sizeof(struct rand_buffer));
if (buf == NULL) {
return NULL;
}
buf->used = BUF_SIZE; /* To trigger a |read_full| on first use. */
if (!CRYPTO_set_thread_local(OPENSSL_THREAD_LOCAL_URANDOM_BUF, buf,
OPENSSL_free)) {
OPENSSL_free(buf);
return NULL;
}
return buf;
}
/* read_full reads exactly |len| bytes from |fd| into |out| and returns 1. In
* the case of an error it returns 0. */
static char read_full(int fd, uint8_t *out, size_t len) {
ssize_t r;
while (len > 0) {
do {
r = read(fd, out, len);
} while (r == -1 && errno == EINTR);
if (r <= 0) {
return 0;
}
out += r;
len -= r;
}
return 1;
}
/* read_from_buffer reads |requested| random bytes from the buffer into |out|,
* refilling it if necessary to satisfy the request. */
static void read_from_buffer(struct rand_buffer *buf,
uint8_t *out, size_t requested) {
size_t remaining = BUF_SIZE - buf->used;
while (requested > remaining) {
memcpy(out, &buf->rand[buf->used], remaining);
buf->used += remaining;
out += remaining;
requested -= remaining;
if (!read_full(urandom_fd, buf->rand, BUF_SIZE)) {
abort();
return;
}
buf->used = 0;
remaining = BUF_SIZE;
}
memcpy(out, &buf->rand[buf->used], requested);
buf->used += requested;
}
/* CRYPTO_sysrand puts |requested| random bytes into |out|. */
void CRYPTO_sysrand(uint8_t *out, size_t requested) {
if (requested == 0) {
return;
}
CRYPTO_once(&once, init_once);
if (urandom_buffering && requested < BUF_SIZE) {
struct rand_buffer *buf = get_thread_local_buffer();
if (buf != NULL) {
read_from_buffer(buf, out, requested);
return;
}
}
if (!read_full(urandom_fd, out, requested)) {
abort();
}
}
#endif /* !OPENSSL_WINDOWS */
|
