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/param.h>
39 #include <sys/limits.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>
61 #include "unit_test.h"
64 #include <crypto/rijndael/rijndael-api-fst.h>
65 #include <crypto/sha2/sha256.h>
67 #include <dev/random/hash.h>
68 #include <dev/random/randomdev.h>
70 #include <dev/random/random_harvestq.h>
72 #include <dev/random/uint128.h>
73 #include <dev/random/fortuna.h>
76 #define RANDOM_FORTUNA_NPOOLS 32 /* The number of accumulation pools */
77 #define RANDOM_FORTUNA_DEFPOOLSIZE 64 /* The default pool size/length for a (re)seed */
78 #define RANDOM_FORTUNA_MAX_READ (1 << 20) /* Max bytes in a single read */
81 * The allowable range of RANDOM_FORTUNA_DEFPOOLSIZE. The default value is above.
82 * Making RANDOM_FORTUNA_DEFPOOLSIZE too large will mean a long time between reseeds,
83 * and too small may compromise initial security but get faster reseeds.
85 #define RANDOM_FORTUNA_MINPOOLSIZE 16
86 #define RANDOM_FORTUNA_MAXPOOLSIZE INT_MAX
87 CTASSERT(RANDOM_FORTUNA_MINPOOLSIZE <= RANDOM_FORTUNA_DEFPOOLSIZE);
88 CTASSERT(RANDOM_FORTUNA_DEFPOOLSIZE <= RANDOM_FORTUNA_MAXPOOLSIZE);
90 /* This algorithm (and code) presumes that RANDOM_KEYSIZE is twice as large as RANDOM_BLOCKSIZE */
91 CTASSERT(RANDOM_BLOCKSIZE == sizeof(uint128_t));
92 CTASSERT(RANDOM_KEYSIZE == 2*RANDOM_BLOCKSIZE);
94 /* Probes for dtrace(1) */
96 SDT_PROVIDER_DECLARE(random);
97 SDT_PROVIDER_DEFINE(random);
98 SDT_PROBE_DEFINE2(random, fortuna, event_processor, debug, "u_int", "struct fs_pool *");
102 * This is the beastie that needs protecting. It contains all of the
103 * state that we are excited about. Exactly one is instantiated.
105 static struct fortuna_state {
106 struct fs_pool { /* P_i */
107 u_int fsp_length; /* Only the first one is used by Fortuna */
108 struct randomdev_hash fsp_hash;
109 } fs_pool[RANDOM_FORTUNA_NPOOLS];
110 u_int fs_reseedcount; /* ReseedCnt */
111 uint128_t fs_counter; /* C */
112 union randomdev_key fs_key; /* K */
113 u_int fs_minpoolsize; /* Extras */
114 /* Extras for the OS */
116 /* For use when 'pacing' the reseeds */
117 sbintime_t fs_lasttime;
124 static struct sysctl_ctx_list random_clist;
125 RANDOM_CHECK_UINT(fs_minpoolsize, RANDOM_FORTUNA_MINPOOLSIZE, RANDOM_FORTUNA_MAXPOOLSIZE);
127 static uint8_t zero_region[RANDOM_ZERO_BLOCKSIZE];
130 static void random_fortuna_pre_read(void);
131 static void random_fortuna_read(uint8_t *, u_int);
132 static bool random_fortuna_seeded(void);
133 static bool random_fortuna_seeded_internal(void);
134 static void random_fortuna_process_event(struct harvest_event *);
135 static void random_fortuna_init_alg(void *);
136 static void random_fortuna_deinit_alg(void *);
138 static void random_fortuna_reseed_internal(uint32_t *entropy_data, u_int blockcount);
140 struct random_algorithm random_alg_context = {
141 .ra_ident = "Fortuna",
142 .ra_init_alg = random_fortuna_init_alg,
143 .ra_deinit_alg = random_fortuna_deinit_alg,
144 .ra_pre_read = random_fortuna_pre_read,
145 .ra_read = random_fortuna_read,
146 .ra_seeded = random_fortuna_seeded,
147 .ra_event_processor = random_fortuna_process_event,
148 .ra_poolcount = RANDOM_FORTUNA_NPOOLS,
153 random_fortuna_init_alg(void *unused __unused)
157 struct sysctl_oid *random_fortuna_o;
160 RANDOM_RESEED_INIT_LOCK();
162 * Fortuna parameters. Do not adjust these unless you have
163 * have a very good clue about what they do!
165 fortuna_state.fs_minpoolsize = RANDOM_FORTUNA_DEFPOOLSIZE;
167 fortuna_state.fs_lasttime = 0;
168 random_fortuna_o = SYSCTL_ADD_NODE(&random_clist,
169 SYSCTL_STATIC_CHILDREN(_kern_random),
170 OID_AUTO, "fortuna", CTLFLAG_RW, 0,
171 "Fortuna Parameters");
172 SYSCTL_ADD_PROC(&random_clist,
173 SYSCTL_CHILDREN(random_fortuna_o), OID_AUTO,
174 "minpoolsize", CTLTYPE_UINT | CTLFLAG_RWTUN,
175 &fortuna_state.fs_minpoolsize, RANDOM_FORTUNA_DEFPOOLSIZE,
176 random_check_uint_fs_minpoolsize, "IU",
177 "Minimum pool size necessary to cause a reseed");
178 KASSERT(fortuna_state.fs_minpoolsize > 0, ("random: Fortuna threshold must be > 0 at startup"));
182 * FS&K - InitializePRNG()
186 for (i = 0; i < RANDOM_FORTUNA_NPOOLS; i++) {
187 randomdev_hash_init(&fortuna_state.fs_pool[i].fsp_hash);
188 fortuna_state.fs_pool[i].fsp_length = 0;
190 fortuna_state.fs_reseedcount = 0;
192 * FS&K - InitializeGenerator()
196 fortuna_state.fs_counter = UINT128_ZERO;
197 explicit_bzero(&fortuna_state.fs_key, sizeof(fortuna_state.fs_key));
202 random_fortuna_deinit_alg(void *unused __unused)
205 RANDOM_RESEED_DEINIT_LOCK();
206 explicit_bzero(&fortuna_state, sizeof(fortuna_state));
208 sysctl_ctx_free(&random_clist);
213 * FS&K - AddRandomEvent()
214 * Process a single stochastic event off the harvest queue
217 random_fortuna_process_event(struct harvest_event *event)
221 RANDOM_RESEED_LOCK();
223 * FS&K - P_i = P_i|<harvested stuff>
224 * Accumulate the event into the appropriate pool
225 * where each event carries the destination information.
227 * The hash_init() and hash_finish() calls are done in
228 * random_fortuna_pre_read().
230 * We must be locked against pool state modification which can happen
231 * during accumulation/reseeding and reading/regating.
233 pl = event->he_destination % RANDOM_FORTUNA_NPOOLS;
235 * We ignore low entropy static/counter fields towards the end of the
236 * he_event structure in order to increase measurable entropy when
237 * conducting SP800-90B entropy analysis measurements of seed material
241 KASSERT(event->he_size <= sizeof(event->he_entropy),
242 ("%s: event->he_size: %hhu > sizeof(event->he_entropy): %zu\n",
243 __func__, event->he_size, sizeof(event->he_entropy)));
244 randomdev_hash_iterate(&fortuna_state.fs_pool[pl].fsp_hash,
245 &event->he_somecounter, sizeof(event->he_somecounter));
246 randomdev_hash_iterate(&fortuna_state.fs_pool[pl].fsp_hash,
247 event->he_entropy, event->he_size);
250 * Don't wrap the length. This is a "saturating" add.
251 * XXX: FIX!!: We don't actually need lengths for anything but fs_pool[0],
252 * but it's been useful debugging to see them all.
254 fortuna_state.fs_pool[pl].fsp_length = MIN(RANDOM_FORTUNA_MAXPOOLSIZE,
255 fortuna_state.fs_pool[pl].fsp_length +
256 sizeof(event->he_somecounter) + event->he_size);
257 RANDOM_RESEED_UNLOCK();
262 * This introduces new key material into the output generator.
263 * Additionally it increments the output generator's counter
264 * variable C. When C > 0, the output generator is seeded and
265 * will deliver output.
266 * The entropy_data buffer passed is a very specific size; the
267 * product of RANDOM_FORTUNA_NPOOLS and RANDOM_KEYSIZE.
270 random_fortuna_reseed_internal(uint32_t *entropy_data, u_int blockcount)
272 struct randomdev_hash context;
273 uint8_t hash[RANDOM_KEYSIZE];
274 const void *keymaterial;
278 RANDOM_RESEED_ASSERT_LOCK_OWNED();
280 seeded = random_fortuna_seeded_internal();
282 randomdev_getkey(&fortuna_state.fs_key, &keymaterial, &keysz);
283 KASSERT(keysz == RANDOM_KEYSIZE, ("%s: key size %zu not %u",
284 __func__, keysz, (unsigned)RANDOM_KEYSIZE));
288 * FS&K - K = Hd(K|s) where Hd(m) is H(H(0^512|m))
291 randomdev_hash_init(&context);
292 randomdev_hash_iterate(&context, zero_region, RANDOM_ZERO_BLOCKSIZE);
294 randomdev_hash_iterate(&context, keymaterial, keysz);
295 randomdev_hash_iterate(&context, entropy_data, RANDOM_KEYSIZE*blockcount);
296 randomdev_hash_finish(&context, hash);
297 randomdev_hash_init(&context);
298 randomdev_hash_iterate(&context, hash, RANDOM_KEYSIZE);
299 randomdev_hash_finish(&context, hash);
300 randomdev_encrypt_init(&fortuna_state.fs_key, hash);
301 explicit_bzero(hash, sizeof(hash));
302 /* Unblock the device if this is the first time we are reseeding. */
303 if (uint128_is_zero(fortuna_state.fs_counter))
305 uint128_increment(&fortuna_state.fs_counter);
309 * FS&K - GenerateBlocks()
310 * Generate a number of complete blocks of random output.
313 random_fortuna_genblocks(uint8_t *buf, u_int blockcount)
316 RANDOM_RESEED_ASSERT_LOCK_OWNED();
317 KASSERT(!uint128_is_zero(fortuna_state.fs_counter), ("FS&K: C != 0"));
320 * Fills buf with RANDOM_BLOCKSIZE * blockcount bytes of keystream.
321 * Increments fs_counter as it goes.
323 randomdev_keystream(&fortuna_state.fs_key, &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
381 * FS&K - Use 'getsbinuptime()' to prevent reseed-spamming, but do
382 * not block initial seeding (fs_lasttime == 0).
384 || (__predict_true(fortuna_state.fs_lasttime != 0) &&
385 now - fortuna_state.fs_lasttime <= SBT_1S/10)
388 RANDOM_RESEED_UNLOCK();
394 * When set, pretend we do not have enough entropy to reseed yet.
396 KFAIL_POINT_CODE(DEBUG_FP, random_fortuna_pre_read, {
397 if (RETURN_VALUE != 0) {
398 RANDOM_RESEED_UNLOCK();
405 fortuna_state.fs_lasttime = now;
408 /* FS&K - ReseedCNT = ReseedCNT + 1 */
409 fortuna_state.fs_reseedcount++;
410 /* s = \epsilon at start */
411 for (i = 0; i < RANDOM_FORTUNA_NPOOLS; i++) {
412 /* FS&K - if Divides(ReseedCnt, 2^i) ... */
413 if ((fortuna_state.fs_reseedcount % (1 << i)) == 0) {
415 * FS&K - temp = (P_i)
419 randomdev_hash_finish(&fortuna_state.fs_pool[i].fsp_hash, temp);
420 randomdev_hash_init(&fortuna_state.fs_pool[i].fsp_hash);
421 fortuna_state.fs_pool[i].fsp_length = 0;
422 randomdev_hash_init(&context);
423 randomdev_hash_iterate(&context, temp, RANDOM_KEYSIZE);
424 randomdev_hash_finish(&context, s + i*RANDOM_KEYSIZE_WORDS);
429 SDT_PROBE2(random, fortuna, event_processor, debug, fortuna_state.fs_reseedcount, fortuna_state.fs_pool);
432 random_fortuna_reseed_internal(s, i);
433 RANDOM_RESEED_UNLOCK();
435 /* Clean up and secure */
436 explicit_bzero(s, sizeof(s));
437 explicit_bzero(temp, sizeof(temp));
441 * FS&K - RandomData() (Part 2)
442 * Main read from Fortuna, continued. May be called multiple times after
443 * the random_fortuna_pre_read() above.
444 * The supplied buf MUST be a multiple of RANDOM_BLOCKSIZE in size.
445 * Lots of code presumes this for efficiency, both here and in other
446 * routines. You are NOT allowed to break this!
449 random_fortuna_read(uint8_t *buf, u_int bytecount)
452 KASSERT((bytecount % RANDOM_BLOCKSIZE) == 0, ("%s(): bytecount (= %d) must be a multiple of %d", __func__, bytecount, RANDOM_BLOCKSIZE ));
453 RANDOM_RESEED_LOCK();
454 random_fortuna_genrandom(buf, bytecount);
455 RANDOM_RESEED_UNLOCK();
459 static bool block_seeded_status = false;
460 SYSCTL_BOOL(_kern_random, OID_AUTO, block_seeded_status, CTLFLAG_RWTUN,
461 &block_seeded_status, 0,
462 "If non-zero, pretend Fortuna is in an unseeded state. By setting "
463 "this as a tunable, boot can be tested as if the random device is "
468 random_fortuna_seeded_internal(void)
470 return (!uint128_is_zero(fortuna_state.fs_counter));
474 random_fortuna_seeded(void)
478 if (block_seeded_status)
482 if (__predict_true(random_fortuna_seeded_internal()))
486 * Maybe we have enough entropy in the zeroth pool but just haven't
487 * kicked the initial seed step. Do so now.
489 random_fortuna_pre_read();
491 return (random_fortuna_seeded_internal());