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Member "sudo-1.9.11p3/lib/util/arc4random.c" (12 Jun 2022, 4784 Bytes) of package /linux/misc/sudo-1.9.11p3.tar.gz:
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1 /* $OpenBSD: arc4random.c,v 1.54 2015/09/13 08:31:47 guenther Exp $ */
2
3 /*
4 * SPDX-License-Identifier: ISC
5 *
6 * Copyright (c) 1996, David Mazieres <dm@uun.org>
7 * Copyright (c) 2008, Damien Miller <djm@openbsd.org>
8 * Copyright (c) 2013, Markus Friedl <markus@openbsd.org>
9 * Copyright (c) 2014, Theo de Raadt <deraadt@openbsd.org>
10 *
11 * Permission to use, copy, modify, and distribute this software for any
12 * purpose with or without fee is hereby granted, provided that the above
13 * copyright notice and this permission notice appear in all copies.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
16 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
17 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
18 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
19 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
20 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
21 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
22 */
23
24 /*
25 * This is an open source non-commercial project. Dear PVS-Studio, please check it.
26 * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
27 */
28
29 /*
30 * ChaCha based random number generator for OpenBSD.
31 */
32
33 #include <config.h>
34
35 #ifndef HAVE_ARC4RANDOM
36
37 #ifdef HAVE_SYS_RANDOM_H
38 # include <sys/random.h>
39 #endif
40
41 #include <fcntl.h>
42 #include <limits.h>
43 #include <signal.h>
44 #include <stdlib.h>
45 #include <string.h>
46 #include <unistd.h>
47 #if defined(HAVE_STDINT_H)
48 # include <stdint.h>
49 #elif defined(HAVE_INTTYPES_H)
50 # include <inttypes.h>
51 #endif
52
53 #include "sudo_compat.h"
54 #include "sudo_fatal.h"
55 #include "sudo_rand.h"
56
57 #define KEYSTREAM_ONLY
58 #include "chacha_private.h"
59
60 #define minimum(a, b) ((a) < (b) ? (a) : (b))
61
62 #ifdef __GNUC__
63 # define inline __inline
64 #else /* !__GNUC__ */
65 # define inline
66 #endif /* !__GNUC__ */
67
68 /* Sudo isn't multithreaded */
69 #define _ARC4_LOCK()
70 #define _ARC4_UNLOCK()
71
72 #define KEYSZ 32
73 #define IVSZ 8
74 #define BLOCKSZ 64
75 #define RSBUFSZ (16*BLOCKSZ)
76 static int rs_initialized;
77 static pid_t rs_stir_pid;
78 static chacha_ctx rs; /* chacha context for random keystream */
79 static u_char rs_buf[RSBUFSZ]; /* keystream blocks */
80 static size_t rs_have; /* valid bytes at end of rs_buf */
81 static size_t rs_count; /* bytes till reseed */
82
83 static inline void _rs_rekey(unsigned char *dat, size_t datlen);
84
85 static inline void
86 _rs_init(unsigned char *buf, size_t n)
87 {
88 if (n < KEYSZ + IVSZ)
89 return;
90 chacha_keysetup(&rs, buf, KEYSZ * 8, 0);
91 chacha_ivsetup(&rs, buf + KEYSZ);
92 }
93
94 static void
95 _rs_stir(void)
96 {
97 unsigned char rnd[KEYSZ + IVSZ];
98
99 if (getentropy(rnd, sizeof rnd) == -1)
100 sudo_fatal_nodebug("getentropy");
101
102 if (!rs_initialized) {
103 rs_initialized = 1;
104 _rs_init(rnd, sizeof(rnd));
105 } else
106 _rs_rekey(rnd, sizeof(rnd));
107 explicit_bzero(rnd, sizeof(rnd)); /* discard source seed */
108
109 /* invalidate rs_buf */
110 rs_have = 0;
111 memset(rs_buf, 0, sizeof(rs_buf));
112
113 rs_count = 1600000;
114 }
115
116 static inline void
117 _rs_stir_if_needed(size_t len)
118 {
119 pid_t pid = getpid();
120
121 if (rs_count <= len || !rs_initialized || rs_stir_pid != pid) {
122 rs_stir_pid = pid;
123 _rs_stir();
124 } else
125 rs_count -= len;
126 }
127
128 static inline void
129 _rs_rekey(unsigned char *dat, size_t datlen)
130 {
131 #ifndef KEYSTREAM_ONLY
132 memset(rs_buf, 0, sizeof(rs_buf));
133 #endif
134 /* fill rs_buf with the keystream */
135 chacha_encrypt_bytes(&rs, rs_buf, rs_buf, sizeof(rs_buf));
136 /* mix in optional user provided data */
137 if (dat) {
138 size_t i, m;
139
140 m = minimum(datlen, KEYSZ + IVSZ);
141 for (i = 0; i < m; i++)
142 rs_buf[i] ^= dat[i];
143 }
144 /* immediately reinit for backtracking resistance */
145 _rs_init(rs_buf, KEYSZ + IVSZ);
146 memset(rs_buf, 0, KEYSZ + IVSZ); // -V512
147 rs_have = sizeof(rs_buf) - KEYSZ - IVSZ;
148 }
149
150 static inline void
151 _rs_random_buf(void *_buf, size_t n)
152 {
153 unsigned char *buf = (unsigned char *)_buf;
154 unsigned char *keystream;
155 size_t m;
156
157 _rs_stir_if_needed(n);
158 while (n > 0) {
159 if (rs_have > 0) {
160 m = minimum(n, rs_have);
161 keystream = rs_buf + sizeof(rs_buf) - rs_have;
162 memcpy(buf, keystream, m);
163 memset(keystream, 0, m);
164 buf += m;
165 n -= m;
166 rs_have -= m;
167 }
168 if (rs_have == 0)
169 _rs_rekey(NULL, 0);
170 }
171 }
172
173 static inline void
174 _rs_random_u32(uint32_t *val)
175 {
176 unsigned char *keystream;
177
178 _rs_stir_if_needed(sizeof(*val));
179 if (rs_have < sizeof(*val))
180 _rs_rekey(NULL, 0);
181 keystream = rs_buf + sizeof(rs_buf) - rs_have;
182 memcpy(val, keystream, sizeof(*val));
183 memset(keystream, 0, sizeof(*val));
184 rs_have -= sizeof(*val);
185 }
186
187 uint32_t
188 sudo_arc4random(void)
189 {
190 uint32_t val;
191
192 _ARC4_LOCK();
193 _rs_random_u32(&val);
194 _ARC4_UNLOCK();
195 return val;
196 }
197
198 void
199 sudo_arc4random_buf(void *buf, size_t n)
200 {
201 _ARC4_LOCK();
202 _rs_random_buf(buf, n);
203 _ARC4_UNLOCK();
204 }
205
206 #endif /* HAVE_ARC4RANDOM */