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
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
|
/* random.c -- Functions for managing 16-bit and 32-bit random numbers. */
/* Copyright (C) 2020 Free Software Foundation, Inc.
This file is part of GNU Bash, the Bourne Again SHell.
Bash is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Bash is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Bash. If not, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include "bashtypes.h"
#if defined (HAVE_SYS_RANDOM_H)
# include <sys/random.h>
#endif
#if defined (HAVE_UNISTD_H)
# include <unistd.h>
#endif
#include "filecntl.h"
#include <stdio.h>
#include "bashansi.h"
#include "shell.h"
extern time_t shell_start_time;
extern int last_random_value;
static u_bits32_t intrand32 PARAMS((u_bits32_t));
static u_bits32_t genseed PARAMS((void));
static u_bits32_t brand32 PARAMS((void));
static void sbrand32 PARAMS((u_bits32_t));
static void perturb_rand32 PARAMS((void));
/* The random number seed. You can change this by setting RANDOM. */
static u_bits32_t rseed = 1;
/* Returns a 32-bit pseudo-random number. */
static u_bits32_t
intrand32 (last)
u_bits32_t last;
{
/* Minimal Standard generator from
"Random number generators: good ones are hard to find",
Park and Miller, Communications of the ACM, vol. 31, no. 10,
October 1988, p. 1195. Filtered through FreeBSD.
x(n+1) = 16807 * x(n) mod (m).
We split up the calculations to avoid overflow.
h = last / q; l = x - h * q; t = a * l - h * r
m = 2147483647, a = 16807, q = 127773, r = 2836
There are lots of other combinations of constants to use; look at
https://www.gnu.org/software/gsl/manual/html_node/Other-random-number-generators.html#Other-random-number-generators */
bits32_t h, l, t;
u_bits32_t ret;
/* Can't seed with 0. */
ret = (last == 0) ? 123459876 : last;
h = ret / 127773;
l = ret - (127773 * h);
t = 16807 * l - 2836 * h;
ret = (t < 0) ? t + 0x7fffffff : t;
return (ret);
}
static u_bits32_t
genseed ()
{
struct timeval tv;
u_bits32_t iv;
gettimeofday (&tv, NULL);
iv = (u_bits32_t)seedrand; /* let the compiler truncate */
iv = tv.tv_sec ^ tv.tv_usec ^ getpid () ^ getppid () ^ current_user.uid ^ iv;
return (iv);
}
#define BASH_RAND_MAX 32767 /* 0x7fff - 16 bits */
/* Returns a pseudo-random number between 0 and 32767. */
int
brand ()
{
unsigned int ret;
rseed = intrand32 (rseed);
if (shell_compatibility_level > 50)
ret = (rseed >> 16) ^ (rseed & 65535);
else
ret = rseed;
return (ret & BASH_RAND_MAX);
}
/* Set the random number generator seed to SEED. */
void
sbrand (seed)
unsigned long seed;
{
rseed = seed;
last_random_value = 0;
}
void
seedrand ()
{
u_bits32_t iv;
iv = genseed ();
sbrand (iv);
}
static u_bits32_t rseed32 = 1073741823;
static int last_rand32;
static int urandfd = -1;
#define BASH_RAND32_MAX 0x7fffffff /* 32 bits */
/* Returns a 32-bit pseudo-random number between 0 and 4294967295. */
static u_bits32_t
brand32 ()
{
u_bits32_t ret;
rseed32 = intrand32 (rseed32);
return (rseed32 & BASH_RAND32_MAX);
}
static void
sbrand32 (seed)
u_bits32_t seed;
{
last_rand32 = rseed32 = seed;
}
void
seedrand32 ()
{
u_bits32_t iv;
iv = genseed ();
sbrand32 (iv);
}
static void
perturb_rand32 ()
{
rseed32 ^= genseed ();
}
/* Force another attempt to open /dev/urandom on the next call to get_urandom32 */
void
urandom_close ()
{
if (urandfd >= 0)
close (urandfd);
urandfd = -1;
}
#if !defined (HAVE_GETRANDOM)
/* Imperfect emulation of getrandom(2). */
#ifndef GRND_NONBLOCK
# define GRND_NONBLOCK 1
# define GRND_RANDOM 2
#endif
static ssize_t
getrandom (buf, len, flags)
void *buf;
size_t len;
unsigned int flags;
{
int oflags;
ssize_t r;
static int urand_unavail = 0;
#if HAVE_GETENTROPY
r = getentropy (buf, len);
return (r == 0) ? len : -1;
#endif
if (urandfd == -1 && urand_unavail == 0)
{
oflags = O_RDONLY;
if (flags & GRND_NONBLOCK)
oflags |= O_NONBLOCK;
urandfd = open ("/dev/urandom", oflags, 0);
if (urandfd >= 0)
SET_CLOSE_ON_EXEC (urandfd);
else
{
urand_unavail = 1;
return -1;
}
}
if (urandfd >= 0 && (r = read (urandfd, buf, len)) == len)
return (r);
return -1;
}
#endif
u_bits32_t
get_urandom32 ()
{
u_bits32_t ret;
if (getrandom ((void *)&ret, sizeof (ret), GRND_NONBLOCK) == sizeof (ret))
return (last_rand32 = ret);
#if defined (HAVE_ARC4RANDOM)
ret = arc4random ();
#else
if (subshell_environment)
perturb_rand32 ();
do
ret = brand32 ();
while (ret == last_rand32);
#endif
return (last_rand32 = ret);
}
|
