2 * Copyright (c) 2017 W. Dean Freeman
3 * Copyright (c) 2013-2015 Mark R V Murray
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer
11 * in this position and unchanged.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 * This implementation of Fortuna is based on the descriptions found in
31 * ISBN 978-0-470-47424-2 "Cryptography Engineering" by Ferguson, Schneier
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
38 #include <sys/limits.h>
41 #include <sys/param.h>
43 #include <sys/kernel.h>
45 #include <sys/malloc.h>
46 #include <sys/mutex.h>
47 #include <sys/random.h>
49 #include <sys/sysctl.h>
50 #include <sys/systm.h>
52 #include <machine/cpu.h>
54 #include <crypto/rijndael/rijndael-api-fst.h>
55 #include <crypto/sha2/sha256.h>
57 #include <dev/random/hash.h>
58 #include <dev/random/randomdev.h>
59 #include <dev/random/random_harvestq.h>
60 #include <dev/random/uint128.h>
61 #include <dev/random/fortuna.h>
63 #include <sys/param.h>
71 #include "unit_test.h"
73 #include <crypto/rijndael/rijndael-api-fst.h>
74 #include <crypto/sha2/sha256.h>
76 #include <dev/random/hash.h>
77 #include <dev/random/randomdev.h>
78 #include <dev/random/uint128.h>
79 #include <dev/random/fortuna.h>
83 #define RANDOM_FORTUNA_NPOOLS 32 /* The number of accumulation pools */
84 #define RANDOM_FORTUNA_DEFPOOLSIZE 64 /* The default pool size/length for a (re)seed */
85 #define RANDOM_FORTUNA_MAX_READ (1 << 20) /* Max bytes in a single read */
88 * The allowable range of RANDOM_FORTUNA_DEFPOOLSIZE. The default value is above.
89 * Making RANDOM_FORTUNA_DEFPOOLSIZE too large will mean a long time between reseeds,
90 * and too small may compromise initial security but get faster reseeds.
92 #define RANDOM_FORTUNA_MINPOOLSIZE 16
93 #define RANDOM_FORTUNA_MAXPOOLSIZE INT_MAX
94 CTASSERT(RANDOM_FORTUNA_MINPOOLSIZE <= RANDOM_FORTUNA_DEFPOOLSIZE);
95 CTASSERT(RANDOM_FORTUNA_DEFPOOLSIZE <= RANDOM_FORTUNA_MAXPOOLSIZE);
97 /* This algorithm (and code) presumes that RANDOM_KEYSIZE is twice as large as RANDOM_BLOCKSIZE */
98 CTASSERT(RANDOM_BLOCKSIZE == sizeof(uint128_t));
99 CTASSERT(RANDOM_KEYSIZE == 2*RANDOM_BLOCKSIZE);
101 /* Probes for dtrace(1) */
103 SDT_PROVIDER_DECLARE(random);
104 SDT_PROVIDER_DEFINE(random);
105 SDT_PROBE_DEFINE2(random, fortuna, event_processor, debug, "u_int", "struct fs_pool *");
109 * This is the beastie that needs protecting. It contains all of the
110 * state that we are excited about. Exactly one is instantiated.
112 static struct fortuna_state {
113 struct fs_pool { /* P_i */
114 u_int fsp_length; /* Only the first one is used by Fortuna */
115 struct randomdev_hash fsp_hash;
116 } fs_pool[RANDOM_FORTUNA_NPOOLS];
117 u_int fs_reseedcount; /* ReseedCnt */
118 uint128_t fs_counter; /* C */
119 struct randomdev_key fs_key; /* K */
120 u_int fs_minpoolsize; /* Extras */
121 /* Extras for the OS */
123 /* For use when 'pacing' the reseeds */
124 sbintime_t fs_lasttime;
131 static struct sysctl_ctx_list random_clist;
132 RANDOM_CHECK_UINT(fs_minpoolsize, RANDOM_FORTUNA_MINPOOLSIZE, RANDOM_FORTUNA_MAXPOOLSIZE);
134 static uint8_t zero_region[RANDOM_ZERO_BLOCKSIZE];
137 static void random_fortuna_pre_read(void);
138 static void random_fortuna_read(uint8_t *, u_int);
139 static bool random_fortuna_seeded(void);
140 static void random_fortuna_process_event(struct harvest_event *);
141 static void random_fortuna_init_alg(void *);
142 static void random_fortuna_deinit_alg(void *);
144 static void random_fortuna_reseed_internal(uint32_t *entropy_data, u_int blockcount);
146 struct random_algorithm random_alg_context = {
147 .ra_ident = "Fortuna",
148 .ra_init_alg = random_fortuna_init_alg,
149 .ra_deinit_alg = random_fortuna_deinit_alg,
150 .ra_pre_read = random_fortuna_pre_read,
151 .ra_read = random_fortuna_read,
152 .ra_seeded = random_fortuna_seeded,
153 .ra_event_processor = random_fortuna_process_event,
154 .ra_poolcount = RANDOM_FORTUNA_NPOOLS,
159 random_fortuna_init_alg(void *unused __unused)
163 struct sysctl_oid *random_fortuna_o;
166 RANDOM_RESEED_INIT_LOCK();
168 * Fortuna parameters. Do not adjust these unless you have
169 * have a very good clue about what they do!
171 fortuna_state.fs_minpoolsize = RANDOM_FORTUNA_DEFPOOLSIZE;
173 fortuna_state.fs_lasttime = 0;
174 random_fortuna_o = SYSCTL_ADD_NODE(&random_clist,
175 SYSCTL_STATIC_CHILDREN(_kern_random),
176 OID_AUTO, "fortuna", CTLFLAG_RW, 0,
177 "Fortuna Parameters");
178 SYSCTL_ADD_PROC(&random_clist,
179 SYSCTL_CHILDREN(random_fortuna_o), OID_AUTO,
180 "minpoolsize", CTLTYPE_UINT | CTLFLAG_RWTUN,
181 &fortuna_state.fs_minpoolsize, RANDOM_FORTUNA_DEFPOOLSIZE,
182 random_check_uint_fs_minpoolsize, "IU",
183 "Minimum pool size necessary to cause a reseed");
184 KASSERT(fortuna_state.fs_minpoolsize > 0, ("random: Fortuna threshold must be > 0 at startup"));
188 * FS&K - InitializePRNG()
192 for (i = 0; i < RANDOM_FORTUNA_NPOOLS; i++) {
193 randomdev_hash_init(&fortuna_state.fs_pool[i].fsp_hash);
194 fortuna_state.fs_pool[i].fsp_length = 0;
196 fortuna_state.fs_reseedcount = 0;
198 * FS&K - InitializeGenerator()
202 fortuna_state.fs_counter = UINT128_ZERO;
203 explicit_bzero(&fortuna_state.fs_key, sizeof(fortuna_state.fs_key));
208 random_fortuna_deinit_alg(void *unused __unused)
211 RANDOM_RESEED_DEINIT_LOCK();
212 explicit_bzero(&fortuna_state, sizeof(fortuna_state));
214 sysctl_ctx_free(&random_clist);
219 * FS&K - AddRandomEvent()
220 * Process a single stochastic event off the harvest queue
223 random_fortuna_process_event(struct harvest_event *event)
227 RANDOM_RESEED_LOCK();
229 * FS&K - P_i = P_i|<harvested stuff>
230 * Accumulate the event into the appropriate pool
231 * where each event carries the destination information.
233 * The hash_init() and hash_finish() calls are done in
234 * random_fortuna_pre_read().
236 * We must be locked against pool state modification which can happen
237 * during accumulation/reseeding and reading/regating.
239 pl = event->he_destination % RANDOM_FORTUNA_NPOOLS;
241 * We ignore low entropy static/counter fields towards the end of the
242 * he_event structure in order to increase measurable entropy when
243 * conducting SP800-90B entropy analysis measurements of seed material
247 KASSERT(event->he_size <= sizeof(event->he_entropy),
248 ("%s: event->he_size: %hhu > sizeof(event->he_entropy): %zu\n",
249 __func__, event->he_size, sizeof(event->he_entropy)));
250 randomdev_hash_iterate(&fortuna_state.fs_pool[pl].fsp_hash,
251 &event->he_somecounter, sizeof(event->he_somecounter));
252 randomdev_hash_iterate(&fortuna_state.fs_pool[pl].fsp_hash,
253 event->he_entropy, event->he_size);
256 * Don't wrap the length. This is a "saturating" add.
257 * XXX: FIX!!: We don't actually need lengths for anything but fs_pool[0],
258 * but it's been useful debugging to see them all.
260 fortuna_state.fs_pool[pl].fsp_length = MIN(RANDOM_FORTUNA_MAXPOOLSIZE,
261 fortuna_state.fs_pool[pl].fsp_length +
262 sizeof(event->he_somecounter) + event->he_size);
263 explicit_bzero(event, sizeof(*event));
264 RANDOM_RESEED_UNLOCK();
269 * This introduces new key material into the output generator.
270 * Additionally it increments the output generator's counter
271 * variable C. When C > 0, the output generator is seeded and
272 * will deliver output.
273 * The entropy_data buffer passed is a very specific size; the
274 * product of RANDOM_FORTUNA_NPOOLS and RANDOM_KEYSIZE.
277 random_fortuna_reseed_internal(uint32_t *entropy_data, u_int blockcount)
279 struct randomdev_hash context;
280 uint8_t hash[RANDOM_KEYSIZE];
282 RANDOM_RESEED_ASSERT_LOCK_OWNED();
284 * FS&K - K = Hd(K|s) where Hd(m) is H(H(0^512|m))
287 randomdev_hash_init(&context);
288 randomdev_hash_iterate(&context, zero_region, RANDOM_ZERO_BLOCKSIZE);
289 randomdev_hash_iterate(&context, &fortuna_state.fs_key.key.keyMaterial,
290 fortuna_state.fs_key.key.keyLen / 8);
291 randomdev_hash_iterate(&context, entropy_data, RANDOM_KEYSIZE*blockcount);
292 randomdev_hash_finish(&context, hash);
293 randomdev_hash_init(&context);
294 randomdev_hash_iterate(&context, hash, RANDOM_KEYSIZE);
295 randomdev_hash_finish(&context, hash);
296 randomdev_encrypt_init(&fortuna_state.fs_key, hash);
297 explicit_bzero(hash, sizeof(hash));
298 /* Unblock the device if this is the first time we are reseeding. */
299 if (uint128_is_zero(fortuna_state.fs_counter))
301 uint128_increment(&fortuna_state.fs_counter);
305 * FS&K - GenerateBlocks()
306 * Generate a number of complete blocks of random output.
309 random_fortuna_genblocks(uint8_t *buf, u_int blockcount)
313 RANDOM_RESEED_ASSERT_LOCK_OWNED();
314 KASSERT(!uint128_is_zero(fortuna_state.fs_counter), ("FS&K: C != 0"));
316 for (i = 0; i < blockcount; i++) {
318 * FS&K - r = r|E(K,C)
321 randomdev_encrypt(&fortuna_state.fs_key, &fortuna_state.fs_counter, buf, RANDOM_BLOCKSIZE);
322 buf += RANDOM_BLOCKSIZE;
323 uint128_increment(&fortuna_state.fs_counter);
328 * FS&K - PseudoRandomData()
329 * This generates no more than 2^20 bytes of data, and cleans up its
330 * internal state when finished. It is assumed that a whole number of
331 * blocks are available for writing; any excess generated will be
335 random_fortuna_genrandom(uint8_t *buf, u_int bytecount)
337 uint8_t temp[RANDOM_BLOCKSIZE * RANDOM_KEYS_PER_BLOCK];
340 RANDOM_RESEED_ASSERT_LOCK_OWNED();
342 * FS&K - assert(n < 2^20 (== 1 MB)
343 * - r = first-n-bytes(GenerateBlocks(ceil(n/16)))
344 * - K = GenerateBlocks(2)
346 KASSERT((bytecount <= RANDOM_FORTUNA_MAX_READ), ("invalid single read request to Fortuna of %d bytes", bytecount));
347 blockcount = howmany(bytecount, RANDOM_BLOCKSIZE);
348 random_fortuna_genblocks(buf, blockcount);
349 random_fortuna_genblocks(temp, RANDOM_KEYS_PER_BLOCK);
350 randomdev_encrypt_init(&fortuna_state.fs_key, temp);
351 explicit_bzero(temp, sizeof(temp));
355 * FS&K - RandomData() (Part 1)
356 * Used to return processed entropy from the PRNG. There is a pre_read
357 * required to be present (but it can be a stub) in order to allow
358 * specific actions at the begin of the read.
361 random_fortuna_pre_read(void)
366 struct randomdev_hash context;
367 uint32_t s[RANDOM_FORTUNA_NPOOLS*RANDOM_KEYSIZE_WORDS];
368 uint8_t temp[RANDOM_KEYSIZE];
371 KASSERT(fortuna_state.fs_minpoolsize > 0, ("random: Fortuna threshold must be > 0"));
372 RANDOM_RESEED_LOCK();
374 /* FS&K - Use 'getsbinuptime()' to prevent reseed-spamming. */
375 now = getsbinuptime();
378 if (fortuna_state.fs_pool[0].fsp_length < fortuna_state.fs_minpoolsize
380 /* FS&K - Use 'getsbinuptime()' to prevent reseed-spamming. */
381 || (now - fortuna_state.fs_lasttime <= SBT_1S/10)
384 RANDOM_RESEED_UNLOCK();
390 * When set, pretend we do not have enough entropy to reseed yet.
392 KFAIL_POINT_CODE(DEBUG_FP, random_fortuna_pre_read, {
393 if (RETURN_VALUE != 0) {
394 RANDOM_RESEED_UNLOCK();
401 fortuna_state.fs_lasttime = now;
404 /* FS&K - ReseedCNT = ReseedCNT + 1 */
405 fortuna_state.fs_reseedcount++;
406 /* s = \epsilon at start */
407 for (i = 0; i < RANDOM_FORTUNA_NPOOLS; i++) {
408 /* FS&K - if Divides(ReseedCnt, 2^i) ... */
409 if ((fortuna_state.fs_reseedcount % (1 << i)) == 0) {
411 * FS&K - temp = (P_i)
415 randomdev_hash_finish(&fortuna_state.fs_pool[i].fsp_hash, temp);
416 randomdev_hash_init(&fortuna_state.fs_pool[i].fsp_hash);
417 fortuna_state.fs_pool[i].fsp_length = 0;
418 randomdev_hash_init(&context);
419 randomdev_hash_iterate(&context, temp, RANDOM_KEYSIZE);
420 randomdev_hash_finish(&context, s + i*RANDOM_KEYSIZE_WORDS);
425 SDT_PROBE2(random, fortuna, event_processor, debug, fortuna_state.fs_reseedcount, fortuna_state.fs_pool);
428 random_fortuna_reseed_internal(s, i);
429 RANDOM_RESEED_UNLOCK();
431 /* Clean up and secure */
432 explicit_bzero(s, sizeof(s));
433 explicit_bzero(temp, sizeof(temp));
437 * FS&K - RandomData() (Part 2)
438 * Main read from Fortuna, continued. May be called multiple times after
439 * the random_fortuna_pre_read() above.
440 * The supplied buf MUST be a multiple of RANDOM_BLOCKSIZE in size.
441 * Lots of code presumes this for efficiency, both here and in other
442 * routines. You are NOT allowed to break this!
445 random_fortuna_read(uint8_t *buf, u_int bytecount)
448 KASSERT((bytecount % RANDOM_BLOCKSIZE) == 0, ("%s(): bytecount (= %d) must be a multiple of %d", __func__, bytecount, RANDOM_BLOCKSIZE ));
449 RANDOM_RESEED_LOCK();
450 random_fortuna_genrandom(buf, bytecount);
451 RANDOM_RESEED_UNLOCK();
455 random_fortuna_seeded(void)
459 /* When set, act as if we are not seeded. */
460 KFAIL_POINT_CODE(DEBUG_FP, random_fortuna_seeded, {
461 if (RETURN_VALUE != 0)
462 fortuna_state.fs_counter = UINT128_ZERO;
466 return (!uint128_is_zero(fortuna_state.fs_counter));