Line data Source code
1 : /*
2 : * This is a maximally equidistributed combined Tausworthe generator
3 : * based on code from GNU Scientific Library 1.5 (30 Jun 2004)
4 : *
5 : * lfsr113 version:
6 : *
7 : * x_n = (s1_n ^ s2_n ^ s3_n ^ s4_n)
8 : *
9 : * s1_{n+1} = (((s1_n & 4294967294) << 18) ^ (((s1_n << 6) ^ s1_n) >> 13))
10 : * s2_{n+1} = (((s2_n & 4294967288) << 2) ^ (((s2_n << 2) ^ s2_n) >> 27))
11 : * s3_{n+1} = (((s3_n & 4294967280) << 7) ^ (((s3_n << 13) ^ s3_n) >> 21))
12 : * s4_{n+1} = (((s4_n & 4294967168) << 13) ^ (((s4_n << 3) ^ s4_n) >> 12))
13 : *
14 : * The period of this generator is about 2^113 (see erratum paper).
15 : *
16 : * From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe
17 : * Generators", Mathematics of Computation, 65, 213 (1996), 203--213:
18 : * http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
19 : * ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps
20 : *
21 : * There is an erratum in the paper "Tables of Maximally Equidistributed
22 : * Combined LFSR Generators", Mathematics of Computation, 68, 225 (1999),
23 : * 261--269: http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
24 : *
25 : * ... the k_j most significant bits of z_j must be non-zero,
26 : * for each j. (Note: this restriction also applies to the
27 : * computer code given in [4], but was mistakenly not mentioned
28 : * in that paper.)
29 : *
30 : * This affects the seeding procedure by imposing the requirement
31 : * s1 > 1, s2 > 7, s3 > 15, s4 > 127.
32 : */
33 :
34 : #include <linux/types.h>
35 : #include <linux/percpu.h>
36 : #include <linux/export.h>
37 : #include <linux/jiffies.h>
38 : #include <linux/random.h>
39 : #include <linux/sched.h>
40 : #include <asm/unaligned.h>
41 :
42 : #ifdef CONFIG_RANDOM32_SELFTEST
43 : static void __init prandom_state_selftest(void);
44 : #else
45 : static inline void prandom_state_selftest(void)
46 : {
47 : }
48 : #endif
49 :
50 : static DEFINE_PER_CPU(struct rnd_state, net_rand_state);
51 :
52 : /**
53 : * prandom_u32_state - seeded pseudo-random number generator.
54 : * @state: pointer to state structure holding seeded state.
55 : *
56 : * This is used for pseudo-randomness with no outside seeding.
57 : * For more random results, use prandom_u32().
58 : */
59 4905 : u32 prandom_u32_state(struct rnd_state *state)
60 : {
61 : #define TAUSWORTHE(s, a, b, c, d) ((s & c) << d) ^ (((s << a) ^ s) >> b)
62 4905 : state->s1 = TAUSWORTHE(state->s1, 6U, 13U, 4294967294U, 18U);
63 4905 : state->s2 = TAUSWORTHE(state->s2, 2U, 27U, 4294967288U, 2U);
64 4905 : state->s3 = TAUSWORTHE(state->s3, 13U, 21U, 4294967280U, 7U);
65 4905 : state->s4 = TAUSWORTHE(state->s4, 3U, 12U, 4294967168U, 13U);
66 :
67 4905 : return (state->s1 ^ state->s2 ^ state->s3 ^ state->s4);
68 : }
69 : EXPORT_SYMBOL(prandom_u32_state);
70 :
71 : /**
72 : * prandom_u32 - pseudo random number generator
73 : *
74 : * A 32 bit pseudo-random number is generated using a fast
75 : * algorithm suitable for simulation. This algorithm is NOT
76 : * considered safe for cryptographic use.
77 : */
78 359 : u32 prandom_u32(void)
79 : {
80 359 : struct rnd_state *state = &get_cpu_var(net_rand_state);
81 : u32 res;
82 :
83 359 : res = prandom_u32_state(state);
84 718 : put_cpu_var(state);
85 :
86 359 : return res;
87 : }
88 : EXPORT_SYMBOL(prandom_u32);
89 :
90 : /**
91 : * prandom_bytes_state - get the requested number of pseudo-random bytes
92 : *
93 : * @state: pointer to state structure holding seeded state.
94 : * @buf: where to copy the pseudo-random bytes to
95 : * @bytes: the requested number of bytes
96 : *
97 : * This is used for pseudo-randomness with no outside seeding.
98 : * For more random results, use prandom_bytes().
99 : */
100 1 : void prandom_bytes_state(struct rnd_state *state, void *buf, size_t bytes)
101 : {
102 : u8 *ptr = buf;
103 :
104 4098 : while (bytes >= sizeof(u32)) {
105 4096 : put_unaligned(prandom_u32_state(state), (u32 *) ptr);
106 4096 : ptr += sizeof(u32);
107 4096 : bytes -= sizeof(u32);
108 : }
109 :
110 1 : if (bytes > 0) {
111 0 : u32 rem = prandom_u32_state(state);
112 : do {
113 0 : *ptr++ = (u8) rem;
114 0 : bytes--;
115 0 : rem >>= BITS_PER_BYTE;
116 0 : } while (bytes > 0);
117 : }
118 1 : }
119 : EXPORT_SYMBOL(prandom_bytes_state);
120 :
121 : /**
122 : * prandom_bytes - get the requested number of pseudo-random bytes
123 : * @buf: where to copy the pseudo-random bytes to
124 : * @bytes: the requested number of bytes
125 : */
126 1 : void prandom_bytes(void *buf, size_t bytes)
127 : {
128 1 : struct rnd_state *state = &get_cpu_var(net_rand_state);
129 :
130 1 : prandom_bytes_state(state, buf, bytes);
131 2 : put_cpu_var(state);
132 1 : }
133 : EXPORT_SYMBOL(prandom_bytes);
134 :
135 45 : static void prandom_warmup(struct rnd_state *state)
136 : {
137 : /* Calling RNG ten times to satisfy recurrence condition */
138 45 : prandom_u32_state(state);
139 45 : prandom_u32_state(state);
140 45 : prandom_u32_state(state);
141 45 : prandom_u32_state(state);
142 45 : prandom_u32_state(state);
143 45 : prandom_u32_state(state);
144 45 : prandom_u32_state(state);
145 45 : prandom_u32_state(state);
146 45 : prandom_u32_state(state);
147 45 : prandom_u32_state(state);
148 45 : }
149 :
150 : static u32 __extract_hwseed(void)
151 : {
152 : unsigned int val = 0;
153 :
154 : (void)(arch_get_random_seed_int(&val) ||
155 : arch_get_random_int(&val));
156 :
157 : return val;
158 : }
159 :
160 1 : static void prandom_seed_early(struct rnd_state *state, u32 seed,
161 : bool mix_with_hwseed)
162 : {
163 : #define LCG(x) ((x) * 69069U) /* super-duper LCG */
164 : #define HWSEED() (mix_with_hwseed ? __extract_hwseed() : 0)
165 2 : state->s1 = __seed(HWSEED() ^ LCG(seed), 2U);
166 2 : state->s2 = __seed(HWSEED() ^ LCG(state->s1), 8U);
167 2 : state->s3 = __seed(HWSEED() ^ LCG(state->s2), 16U);
168 2 : state->s4 = __seed(HWSEED() ^ LCG(state->s3), 128U);
169 1 : }
170 :
171 : /**
172 : * prandom_seed - add entropy to pseudo random number generator
173 : * @seed: seed value
174 : *
175 : * Add some additional seeding to the prandom pool.
176 : */
177 42 : void prandom_seed(u32 entropy)
178 : {
179 : int i;
180 : /*
181 : * No locking on the CPUs, but then somewhat random results are, well,
182 : * expected.
183 : */
184 84 : for_each_possible_cpu (i) {
185 : struct rnd_state *state = &per_cpu(net_rand_state, i);
186 :
187 84 : state->s1 = __seed(state->s1 ^ entropy, 2U);
188 42 : prandom_warmup(state);
189 : }
190 42 : }
191 : EXPORT_SYMBOL(prandom_seed);
192 :
193 : /*
194 : * Generate some initially weak seeding values to allow
195 : * to start the prandom_u32() engine.
196 : */
197 1 : static int __init prandom_init(void)
198 : {
199 : int i;
200 :
201 : prandom_state_selftest();
202 :
203 2 : for_each_possible_cpu(i) {
204 : struct rnd_state *state = &per_cpu(net_rand_state,i);
205 1 : u32 weak_seed = (i + jiffies) ^ random_get_entropy();
206 :
207 1 : prandom_seed_early(state, weak_seed, true);
208 1 : prandom_warmup(state);
209 : }
210 :
211 1 : return 0;
212 : }
213 : core_initcall(prandom_init);
214 :
215 : static void __prandom_timer(unsigned long dontcare);
216 :
217 : static DEFINE_TIMER(seed_timer, __prandom_timer, 0, 0);
218 :
219 40 : static void __prandom_timer(unsigned long dontcare)
220 : {
221 : u32 entropy;
222 : unsigned long expires;
223 :
224 40 : get_random_bytes(&entropy, sizeof(entropy));
225 40 : prandom_seed(entropy);
226 :
227 : /* reseed every ~60 seconds, in [40 .. 80) interval with slack */
228 40 : expires = 40 + prandom_u32_max(40);
229 40 : seed_timer.expires = jiffies + msecs_to_jiffies(expires * MSEC_PER_SEC);
230 :
231 40 : add_timer(&seed_timer);
232 40 : }
233 :
234 1 : static void __init __prandom_start_seed_timer(void)
235 : {
236 1 : set_timer_slack(&seed_timer, HZ);
237 1 : seed_timer.expires = jiffies + msecs_to_jiffies(40 * MSEC_PER_SEC);
238 1 : add_timer(&seed_timer);
239 1 : }
240 :
241 : /*
242 : * Generate better values after random number generator
243 : * is fully initialized.
244 : */
245 2 : static void __prandom_reseed(bool late)
246 : {
247 : int i;
248 : unsigned long flags;
249 : static bool latch = false;
250 : static DEFINE_SPINLOCK(lock);
251 :
252 : /* Asking for random bytes might result in bytes getting
253 : * moved into the nonblocking pool and thus marking it
254 : * as initialized. In this case we would double back into
255 : * this function and attempt to do a late reseed.
256 : * Ignore the pointless attempt to reseed again if we're
257 : * already waiting for bytes when the nonblocking pool
258 : * got initialized.
259 : */
260 :
261 : /* only allow initial seeding (late == false) once */
262 2 : if (!spin_trylock_irqsave(&lock, flags))
263 2 : return;
264 :
265 2 : if (latch && !late)
266 : goto out;
267 :
268 2 : latch = true;
269 :
270 4 : for_each_possible_cpu(i) {
271 : struct rnd_state *state = &per_cpu(net_rand_state,i);
272 : u32 seeds[4];
273 :
274 2 : get_random_bytes(&seeds, sizeof(seeds));
275 4 : state->s1 = __seed(seeds[0], 2U);
276 4 : state->s2 = __seed(seeds[1], 8U);
277 4 : state->s3 = __seed(seeds[2], 16U);
278 4 : state->s4 = __seed(seeds[3], 128U);
279 :
280 2 : prandom_warmup(state);
281 : }
282 : out:
283 : spin_unlock_irqrestore(&lock, flags);
284 : }
285 :
286 1 : void prandom_reseed_late(void)
287 : {
288 1 : __prandom_reseed(true);
289 1 : }
290 :
291 1 : static int __init prandom_reseed(void)
292 : {
293 1 : __prandom_reseed(false);
294 1 : __prandom_start_seed_timer();
295 1 : return 0;
296 : }
297 : late_initcall(prandom_reseed);
298 :
299 : #ifdef CONFIG_RANDOM32_SELFTEST
300 : static struct prandom_test1 {
301 : u32 seed;
302 : u32 result;
303 : } test1[] = {
304 : { 1U, 3484351685U },
305 : { 2U, 2623130059U },
306 : { 3U, 3125133893U },
307 : { 4U, 984847254U },
308 : };
309 :
310 : static struct prandom_test2 {
311 : u32 seed;
312 : u32 iteration;
313 : u32 result;
314 : } test2[] = {
315 : /* Test cases against taus113 from GSL library. */
316 : { 931557656U, 959U, 2975593782U },
317 : { 1339693295U, 876U, 3887776532U },
318 : { 1545556285U, 961U, 1615538833U },
319 : { 601730776U, 723U, 1776162651U },
320 : { 1027516047U, 687U, 511983079U },
321 : { 416526298U, 700U, 916156552U },
322 : { 1395522032U, 652U, 2222063676U },
323 : { 366221443U, 617U, 2992857763U },
324 : { 1539836965U, 714U, 3783265725U },
325 : { 556206671U, 994U, 799626459U },
326 : { 684907218U, 799U, 367789491U },
327 : { 2121230701U, 931U, 2115467001U },
328 : { 1668516451U, 644U, 3620590685U },
329 : { 768046066U, 883U, 2034077390U },
330 : { 1989159136U, 833U, 1195767305U },
331 : { 536585145U, 996U, 3577259204U },
332 : { 1008129373U, 642U, 1478080776U },
333 : { 1740775604U, 939U, 1264980372U },
334 : { 1967883163U, 508U, 10734624U },
335 : { 1923019697U, 730U, 3821419629U },
336 : { 442079932U, 560U, 3440032343U },
337 : { 1961302714U, 845U, 841962572U },
338 : { 2030205964U, 962U, 1325144227U },
339 : { 1160407529U, 507U, 240940858U },
340 : { 635482502U, 779U, 4200489746U },
341 : { 1252788931U, 699U, 867195434U },
342 : { 1961817131U, 719U, 668237657U },
343 : { 1071468216U, 983U, 917876630U },
344 : { 1281848367U, 932U, 1003100039U },
345 : { 582537119U, 780U, 1127273778U },
346 : { 1973672777U, 853U, 1071368872U },
347 : { 1896756996U, 762U, 1127851055U },
348 : { 847917054U, 500U, 1717499075U },
349 : { 1240520510U, 951U, 2849576657U },
350 : { 1685071682U, 567U, 1961810396U },
351 : { 1516232129U, 557U, 3173877U },
352 : { 1208118903U, 612U, 1613145022U },
353 : { 1817269927U, 693U, 4279122573U },
354 : { 1510091701U, 717U, 638191229U },
355 : { 365916850U, 807U, 600424314U },
356 : { 399324359U, 702U, 1803598116U },
357 : { 1318480274U, 779U, 2074237022U },
358 : { 697758115U, 840U, 1483639402U },
359 : { 1696507773U, 840U, 577415447U },
360 : { 2081979121U, 981U, 3041486449U },
361 : { 955646687U, 742U, 3846494357U },
362 : { 1250683506U, 749U, 836419859U },
363 : { 595003102U, 534U, 366794109U },
364 : { 47485338U, 558U, 3521120834U },
365 : { 619433479U, 610U, 3991783875U },
366 : { 704096520U, 518U, 4139493852U },
367 : { 1712224984U, 606U, 2393312003U },
368 : { 1318233152U, 922U, 3880361134U },
369 : { 855572992U, 761U, 1472974787U },
370 : { 64721421U, 703U, 683860550U },
371 : { 678931758U, 840U, 380616043U },
372 : { 692711973U, 778U, 1382361947U },
373 : { 677703619U, 530U, 2826914161U },
374 : { 92393223U, 586U, 1522128471U },
375 : { 1222592920U, 743U, 3466726667U },
376 : { 358288986U, 695U, 1091956998U },
377 : { 1935056945U, 958U, 514864477U },
378 : { 735675993U, 990U, 1294239989U },
379 : { 1560089402U, 897U, 2238551287U },
380 : { 70616361U, 829U, 22483098U },
381 : { 368234700U, 731U, 2913875084U },
382 : { 20221190U, 879U, 1564152970U },
383 : { 539444654U, 682U, 1835141259U },
384 : { 1314987297U, 840U, 1801114136U },
385 : { 2019295544U, 645U, 3286438930U },
386 : { 469023838U, 716U, 1637918202U },
387 : { 1843754496U, 653U, 2562092152U },
388 : { 400672036U, 809U, 4264212785U },
389 : { 404722249U, 965U, 2704116999U },
390 : { 600702209U, 758U, 584979986U },
391 : { 519953954U, 667U, 2574436237U },
392 : { 1658071126U, 694U, 2214569490U },
393 : { 420480037U, 749U, 3430010866U },
394 : { 690103647U, 969U, 3700758083U },
395 : { 1029424799U, 937U, 3787746841U },
396 : { 2012608669U, 506U, 3362628973U },
397 : { 1535432887U, 998U, 42610943U },
398 : { 1330635533U, 857U, 3040806504U },
399 : { 1223800550U, 539U, 3954229517U },
400 : { 1322411537U, 680U, 3223250324U },
401 : { 1877847898U, 945U, 2915147143U },
402 : { 1646356099U, 874U, 965988280U },
403 : { 805687536U, 744U, 4032277920U },
404 : { 1948093210U, 633U, 1346597684U },
405 : { 392609744U, 783U, 1636083295U },
406 : { 690241304U, 770U, 1201031298U },
407 : { 1360302965U, 696U, 1665394461U },
408 : { 1220090946U, 780U, 1316922812U },
409 : { 447092251U, 500U, 3438743375U },
410 : { 1613868791U, 592U, 828546883U },
411 : { 523430951U, 548U, 2552392304U },
412 : { 726692899U, 810U, 1656872867U },
413 : { 1364340021U, 836U, 3710513486U },
414 : { 1986257729U, 931U, 935013962U },
415 : { 407983964U, 921U, 728767059U },
416 : };
417 :
418 : static void __init prandom_state_selftest(void)
419 : {
420 : int i, j, errors = 0, runs = 0;
421 : bool error = false;
422 :
423 : for (i = 0; i < ARRAY_SIZE(test1); i++) {
424 : struct rnd_state state;
425 :
426 : prandom_seed_early(&state, test1[i].seed, false);
427 : prandom_warmup(&state);
428 :
429 : if (test1[i].result != prandom_u32_state(&state))
430 : error = true;
431 : }
432 :
433 : if (error)
434 : pr_warn("prandom: seed boundary self test failed\n");
435 : else
436 : pr_info("prandom: seed boundary self test passed\n");
437 :
438 : for (i = 0; i < ARRAY_SIZE(test2); i++) {
439 : struct rnd_state state;
440 :
441 : prandom_seed_early(&state, test2[i].seed, false);
442 : prandom_warmup(&state);
443 :
444 : for (j = 0; j < test2[i].iteration - 1; j++)
445 : prandom_u32_state(&state);
446 :
447 : if (test2[i].result != prandom_u32_state(&state))
448 : errors++;
449 :
450 : runs++;
451 : cond_resched();
452 : }
453 :
454 : if (errors)
455 : pr_warn("prandom: %d/%d self tests failed\n", errors, runs);
456 : else
457 : pr_info("prandom: %d self tests passed\n", runs);
458 : }
459 : #endif
|
