xref: /freebsd/sys/dev/random/other_algorithm.c (revision 7fdf597e96a02165cfe22ff357b857d5fa15ed8a)
1 /*-
2  * Copyright (c) 2015-2018 Mark R V Murray
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer
10  *    in this position and unchanged.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  *
26  */
27 
28 /*-
29  * This is a skeleton for folks who wish to build a loadable module
30  * containing an alternative entropy-processing algorithm for random(4).
31  *
32  * The functions below should be completed with the appropriate code,
33  * and the nearby fortuna.c may be consulted for examples of working code.
34  *
35  * The author is willing to provide reasonable help to those wishing to
36  * write such a module for themselves. Please use the markm@ FreeBSD
37  * email address, and ensure that you are developing this on a suitably
38  * supported branch (This is currently 12-CURRENT, and may be no
39  * older than 12-STABLE in the future).
40  */
41 
42 #include <sys/cdefs.h>
43 #include <sys/limits.h>
44 
45 #ifdef _KERNEL
46 #include <sys/param.h>
47 #include <sys/kernel.h>
48 #include <sys/lock.h>
49 #include <sys/malloc.h>
50 #include <sys/mutex.h>
51 #include <sys/random.h>
52 #include <sys/sysctl.h>
53 #include <sys/systm.h>
54 
55 #include <machine/cpu.h>
56 
57 #include <crypto/rijndael/rijndael-api-fst.h>
58 #include <crypto/sha2/sha256.h>
59 
60 #include <dev/random/hash.h>
61 #include <dev/random/randomdev.h>
62 #include <dev/random/random_harvestq.h>
63 #include <dev/random/uint128.h>
64 #include <dev/random/other_algorithm.h>
65 #else /* !_KERNEL */
66 #include <inttypes.h>
67 #include <stdbool.h>
68 #include <stdio.h>
69 #include <stdlib.h>
70 #include <string.h>
71 #include <threads.h>
72 
73 #include "unit_test.h"
74 
75 #include <crypto/rijndael/rijndael-api-fst.h>
76 #include <crypto/sha2/sha256.h>
77 
78 #include <dev/random/hash.h>
79 #include <dev/random/randomdev.h>
80 #include <dev/random/uint128.h>
81 #include <dev/random/other_algorithm.h>
82 #endif /* _KERNEL */
83 
84 static void random_other_pre_read(void);
85 static void random_other_read(uint8_t *, size_t);
86 static bool random_other_seeded(void);
87 static void random_other_process_event(struct harvest_event *);
88 
89 /*
90  * RANDOM_OTHER_NPOOLS is used when reading hardware random
91  * number sources to ensure that each pool gets one read sample
92  * per loop iteration. Fortuna has 32 (0-31).
93  */
94 #define RANDOM_OTHER_NPOOLS 1
95 
96 #ifdef RANDOM_LOADABLE
97 static
98 #endif
99 const struct random_algorithm random_alg_context = {
100 	.ra_ident = "other",
101 	.ra_pre_read = random_other_pre_read,
102 	.ra_read = random_other_read,
103 	.ra_seeded = random_other_seeded,
104 	.ra_event_processor = random_other_process_event,
105 	.ra_poolcount = RANDOM_OTHER_NPOOLS,
106 };
107 
108 /* Use a mutex to protect your reseed variables? */
109 static mtx_t other_mtx;
110 
111 /*
112  * Do algorithm-specific initialisation here.
113  */
114 static void
115 random_other_init_alg(void *unused __unused)
116 {
117 
118 #ifdef RANDOM_LOADABLE
119 	p_random_alg_context = &random_alg_context;
120 #endif
121 
122 	RANDOM_RESEED_INIT_LOCK();
123 }
124 SYSINIT(random_alg, SI_SUB_RANDOM, SI_ORDER_SECOND, random_other_init_alg,
125     NULL);
126 
127 /*
128  * void random_other_pre_read(void)
129  *
130  * Do any pre-read preparation you need to. This will be called
131  * before >=1 calls to random_other_read() corresponding to one
132  * read(2).
133  *
134  * This routine will be called periodically while the generator is
135  * still blocked and a read is being attempted, giving you an
136  * opportunity to unblock.
137  */
138 static void
139 random_other_pre_read(void)
140 {
141 
142 	RANDOM_RESEED_LOCK();
143 	/*
144 	 * Do pre-read housekeeping work here!
145 	 * You may use this as a chance to unblock the generator.
146 	 */
147 	RANDOM_RESEED_UNLOCK();
148 }
149 
150 /*
151  * void random_other_read(uint8_t *buf, size_t count)
152  *
153  * Generate <count> bytes of output into <*buf>.
154  * You may NOT use the fact that <count> will be a multiple of
155  * RANDOM_BLOCKSIZE for optimization purposes.
156  *
157  * This function will always be called with your generator
158  * unblocked and ready. If you are not ready to generate
159  * output here, then feel free to KASSERT() or panic().
160  */
161 static void
162 random_other_read(uint8_t *buf, size_t count)
163 {
164 
165 	RANDOM_RESEED_LOCK();
166 	/*
167 	 * Do random-number generation work here!
168 	 */
169 	RANDOM_RESEED_UNLOCK();
170 }
171 
172 /*
173  * bool random_other_seeded(void)
174  *
175  * Return true if your generator is ready to generate
176  * output, and false otherwise.
177  */
178 static bool
179 random_other_seeded(void)
180 {
181 	bool seeded = false;
182 
183 	/*
184 	 * Find out if your generator is seeded here!
185 	 */
186 	return (seeded);
187 }
188 
189 /*
190  * void random_other_process_event(struct harvest_event *event)
191  *
192  * Process one stochastic event <*event> into your entropy
193  * processor.
194  *
195  * The structure of the event may change, so it is easier to
196  * just grab the whole thing into your accumulation system.
197  * You may pick-and-choose bits, but please don't complain
198  * when/if these change.
199  */
200 static void
201 random_other_process_event(struct harvest_event *event)
202 {
203 
204 	RANDOM_RESEED_LOCK();
205 	/*
206 	 * Do entropy accumulation work here!
207 	 * You may use this as a chance to unblock the generator.
208 	 */
209 	RANDOM_RESEED_UNLOCK();
210 }
211