xref: /freebsd/sys/dev/random/other_algorithm.c (revision 5b20c5e1f8d59f14901f0c0e4b6b577eaa3f9569)
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 __FBSDID("$FreeBSD$");
44 
45 #include <sys/limits.h>
46 
47 #ifdef _KERNEL
48 #include <sys/param.h>
49 #include <sys/kernel.h>
50 #include <sys/lock.h>
51 #include <sys/malloc.h>
52 #include <sys/mutex.h>
53 #include <sys/random.h>
54 #include <sys/sysctl.h>
55 #include <sys/systm.h>
56 
57 #include <machine/cpu.h>
58 
59 #include <crypto/rijndael/rijndael-api-fst.h>
60 #include <crypto/sha2/sha256.h>
61 
62 #include <dev/random/hash.h>
63 #include <dev/random/randomdev.h>
64 #include <dev/random/random_harvestq.h>
65 #include <dev/random/uint128.h>
66 #include <dev/random/other_algorithm.h>
67 #else /* !_KERNEL */
68 #include <inttypes.h>
69 #include <stdbool.h>
70 #include <stdio.h>
71 #include <stdlib.h>
72 #include <string.h>
73 #include <threads.h>
74 
75 #include "unit_test.h"
76 
77 #include <crypto/rijndael/rijndael-api-fst.h>
78 #include <crypto/sha2/sha256.h>
79 
80 #include <dev/random/hash.h>
81 #include <dev/random/randomdev.h>
82 #include <dev/random/uint128.h>
83 #include <dev/random/other_algorithm.h>
84 #endif /* _KERNEL */
85 
86 static void random_other_pre_read(void);
87 static void random_other_read(uint8_t *, size_t);
88 static bool random_other_seeded(void);
89 static void random_other_process_event(struct harvest_event *);
90 
91 /*
92  * RANDOM_OTHER_NPOOLS is used when reading hardware random
93  * number sources to ensure that each pool gets one read sample
94  * per loop iteration. Fortuna has 32 (0-31).
95  */
96 #define RANDOM_OTHER_NPOOLS 1
97 
98 #ifdef RANDOM_LOADABLE
99 static
100 #endif
101 const struct random_algorithm random_alg_context = {
102 	.ra_ident = "other",
103 	.ra_pre_read = random_other_pre_read,
104 	.ra_read = random_other_read,
105 	.ra_seeded = random_other_seeded,
106 	.ra_event_processor = random_other_process_event,
107 	.ra_poolcount = RANDOM_OTHER_NPOOLS,
108 };
109 
110 /* Use a mutex to protect your reseed variables? */
111 static mtx_t other_mtx;
112 
113 /*
114  * Do algorithm-specific initialisation here.
115  */
116 static void
117 random_other_init_alg(void *unused __unused)
118 {
119 
120 #ifdef RANDOM_LOADABLE
121 	p_random_alg_context = &random_alg_context;
122 #endif
123 
124 	RANDOM_RESEED_INIT_LOCK();
125 }
126 SYSINIT(random_alg, SI_SUB_RANDOM, SI_ORDER_SECOND, random_other_init_alg,
127     NULL);
128 
129 /*
130  * void random_other_pre_read(void)
131  *
132  * Do any pre-read preparation you need to. This will be called
133  * before >=1 calls to random_other_read() corresponding to one
134  * read(2).
135  *
136  * This routine will be called periodically while the generator is
137  * still blocked and a read is being attempted, giving you an
138  * opportunity to unblock.
139  */
140 static void
141 random_other_pre_read(void)
142 {
143 
144 	RANDOM_RESEED_LOCK();
145 	/*
146 	 * Do pre-read housekeeping work here!
147 	 * You may use this as a chance to unblock the generator.
148 	 */
149 	RANDOM_RESEED_UNLOCK();
150 }
151 
152 /*
153  * void random_other_read(uint8_t *buf, size_t count)
154  *
155  * Generate <count> bytes of output into <*buf>.
156  * You may NOT use the fact that <count> will be a multiple of
157  * RANDOM_BLOCKSIZE for optimization purposes.
158  *
159  * This function will always be called with your generator
160  * unblocked and ready. If you are not ready to generate
161  * output here, then feel free to KASSERT() or panic().
162  */
163 static void
164 random_other_read(uint8_t *buf, size_t count)
165 {
166 
167 	RANDOM_RESEED_LOCK();
168 	/*
169 	 * Do random-number generation work here!
170 	 */
171 	RANDOM_RESEED_UNLOCK();
172 }
173 
174 /*
175  * bool random_other_seeded(void)
176  *
177  * Return true if your generator is ready to generate
178  * output, and false otherwise.
179  */
180 static bool
181 random_other_seeded(void)
182 {
183 	bool seeded = false;
184 
185 	/*
186 	 * Find out if your generator is seeded here!
187 	 */
188 	return (seeded);
189 }
190 
191 /*
192  * void random_other_process_event(struct harvest_event *event)
193  *
194  * Process one stochastic event <*event> into your entropy
195  * processor.
196  *
197  * The structure of the event may change, so it is easier to
198  * just grab the whole thing into your accumulation system.
199  * You may pick-and-choose bits, but please don't complain
200  * when/if these change.
201  */
202 static void
203 random_other_process_event(struct harvest_event *event)
204 {
205 
206 	RANDOM_RESEED_LOCK();
207 	/*
208 	 * Do entropy accumulation work here!
209 	 * You may use this as a chance to unblock the generator.
210 	 */
211 	RANDOM_RESEED_UNLOCK();
212 }
213