1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2013 Arthur Mesh <[email protected]>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer
12 * in this position and unchanged.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 */
29
30 #include <sys/cdefs.h>
31 #include <sys/param.h>
32 #include <sys/kernel.h>
33 #include <sys/lock.h>
34 #include <sys/module.h>
35 #include <sys/random.h>
36 #include <sys/systm.h>
37
38 #include <dev/random/randomdev.h>
39 #include <dev/random/randomdev_soft.h>
40 #include <dev/random/random_adaptors.h>
41 #include <dev/random/live_entropy_sources.h>
42
43 static void live_random_example_init(void);
44 static void live_random_example_deinit(void);
45 static u_int live_random_example_read(void *, u_int);
46
47 struct random_adaptor live_random_example = {
48 .les_ident = "Example RNG",
49 .les_source = RANDOM_PURE_BOGUS, /* Make sure this is in
50 * sys/random.h and is unique */
51 .les_read = live_random_example_read,
52 };
53
54 /*
55 * Used under the license provided @ http://xkcd.com/221/
56 * http://creativecommons.org/licenses/by-nc/2.5/
57 */
58 static uint8_t
getRandomNumber(void)59 getRandomNumber(void)
60 {
61 return 4; /* chosen by fair dice roll, guaranteed to be random */
62 }
63
64 static void
live_random_example_init(void)65 live_random_example_init(void)
66 {
67
68 /* Do initialisation stuff here */
69 }
70
71 static void
live_random_example_deinit(void)72 live_random_example_deinit(void)
73 {
74
75 /* Do de-initialisation stuff here */
76 }
77
78 /* get <c> bytes of random stuff into <buf>. You may presume
79 * that <c> is a multiple of 2^n, with n>=3. A typical value
80 * is c=16.
81 */
82 static u_int
live_random_example_read(void * buf,u_int c)83 live_random_example_read(void *buf, u_int c)
84 {
85 uint8_t *b;
86 int count;
87
88 b = buf;
89
90 for (count = 0; count < c; count++)
91 b[count] = getRandomNumber();
92
93 /* printf("returning %d bytes of pure randomness\n", c); */
94 return (c);
95 }
96
97 /* ARGSUSED */
98 static int
live_random_example_modevent(module_t mod __unused,int type,void * unused __unused)99 live_random_example_modevent(module_t mod __unused, int type, void *unused __unused)
100 {
101 int error = 0;
102
103 switch (type) {
104 case MOD_LOAD:
105 live_entropy_source_register(&live_random_example);
106 break;
107
108 case MOD_UNLOAD:
109 live_entropy_source_deregister(&live_random_example);
110 break;
111
112 case MOD_SHUTDOWN:
113 break;
114
115 default:
116 error = EOPNOTSUPP;
117 break;
118 }
119
120 return (error);
121 }
122
123 DEV_MODULE(live_random_example, live_random_example_modevent, NULL);
124 MODULE_VERSION(live_random_example, 1);
125 MODULE_DEPEND(live_random_example, randomdev, 1, 1, 1);
126