blob: fa594b1140e648899410d15920ea5705d7202661
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) __latent_entropy; |
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 | 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 | state->s1 = TAUSWORTHE(state->s1, 6U, 13U, 4294967294U, 18U); |
63 | state->s2 = TAUSWORTHE(state->s2, 2U, 27U, 4294967288U, 2U); |
64 | state->s3 = TAUSWORTHE(state->s3, 13U, 21U, 4294967280U, 7U); |
65 | state->s4 = TAUSWORTHE(state->s4, 3U, 12U, 4294967168U, 13U); |
66 | |
67 | 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 | u32 prandom_u32(void) |
79 | { |
80 | struct rnd_state *state = &get_cpu_var(net_rand_state); |
81 | u32 res; |
82 | |
83 | res = prandom_u32_state(state); |
84 | put_cpu_var(net_rand_state); |
85 | |
86 | 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 | void prandom_bytes_state(struct rnd_state *state, void *buf, size_t bytes) |
101 | { |
102 | u8 *ptr = buf; |
103 | |
104 | while (bytes >= sizeof(u32)) { |
105 | put_unaligned(prandom_u32_state(state), (u32 *) ptr); |
106 | ptr += sizeof(u32); |
107 | bytes -= sizeof(u32); |
108 | } |
109 | |
110 | if (bytes > 0) { |
111 | u32 rem = prandom_u32_state(state); |
112 | do { |
113 | *ptr++ = (u8) rem; |
114 | bytes--; |
115 | rem >>= BITS_PER_BYTE; |
116 | } while (bytes > 0); |
117 | } |
118 | } |
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 | void prandom_bytes(void *buf, size_t bytes) |
127 | { |
128 | struct rnd_state *state = &get_cpu_var(net_rand_state); |
129 | |
130 | prandom_bytes_state(state, buf, bytes); |
131 | put_cpu_var(net_rand_state); |
132 | } |
133 | EXPORT_SYMBOL(prandom_bytes); |
134 | |
135 | static void prandom_warmup(struct rnd_state *state) |
136 | { |
137 | /* Calling RNG ten times to satisfy recurrence condition */ |
138 | prandom_u32_state(state); |
139 | prandom_u32_state(state); |
140 | prandom_u32_state(state); |
141 | prandom_u32_state(state); |
142 | prandom_u32_state(state); |
143 | prandom_u32_state(state); |
144 | prandom_u32_state(state); |
145 | prandom_u32_state(state); |
146 | prandom_u32_state(state); |
147 | prandom_u32_state(state); |
148 | } |
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 | 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 | state->s1 = __seed(HWSEED() ^ LCG(seed), 2U); |
166 | state->s2 = __seed(HWSEED() ^ LCG(state->s1), 8U); |
167 | state->s3 = __seed(HWSEED() ^ LCG(state->s2), 16U); |
168 | state->s4 = __seed(HWSEED() ^ LCG(state->s3), 128U); |
169 | } |
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 | 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 | for_each_possible_cpu(i) { |
185 | struct rnd_state *state = &per_cpu(net_rand_state, i); |
186 | |
187 | state->s1 = __seed(state->s1 ^ entropy, 2U); |
188 | prandom_warmup(state); |
189 | } |
190 | } |
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 | static int __init prandom_init(void) |
198 | { |
199 | int i; |
200 | |
201 | prandom_state_selftest(); |
202 | |
203 | for_each_possible_cpu(i) { |
204 | struct rnd_state *state = &per_cpu(net_rand_state, i); |
205 | u32 weak_seed = (i + jiffies) ^ random_get_entropy(); |
206 | |
207 | prandom_seed_early(state, weak_seed, true); |
208 | prandom_warmup(state); |
209 | } |
210 | |
211 | 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 | static void __prandom_timer(unsigned long dontcare) |
220 | { |
221 | u32 entropy; |
222 | unsigned long expires; |
223 | |
224 | get_random_bytes(&entropy, sizeof(entropy)); |
225 | prandom_seed(entropy); |
226 | |
227 | /* reseed every ~60 seconds, in [40 .. 80) interval with slack */ |
228 | expires = 40 + prandom_u32_max(40); |
229 | seed_timer.expires = jiffies + msecs_to_jiffies(expires * MSEC_PER_SEC); |
230 | |
231 | add_timer(&seed_timer); |
232 | } |
233 | |
234 | static void __init __prandom_start_seed_timer(void) |
235 | { |
236 | seed_timer.expires = jiffies + msecs_to_jiffies(40 * MSEC_PER_SEC); |
237 | add_timer(&seed_timer); |
238 | } |
239 | |
240 | void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state) |
241 | { |
242 | int i; |
243 | |
244 | for_each_possible_cpu(i) { |
245 | struct rnd_state *state = per_cpu_ptr(pcpu_state, i); |
246 | u32 seeds[4]; |
247 | |
248 | get_random_bytes(&seeds, sizeof(seeds)); |
249 | state->s1 = __seed(seeds[0], 2U); |
250 | state->s2 = __seed(seeds[1], 8U); |
251 | state->s3 = __seed(seeds[2], 16U); |
252 | state->s4 = __seed(seeds[3], 128U); |
253 | |
254 | prandom_warmup(state); |
255 | } |
256 | } |
257 | EXPORT_SYMBOL(prandom_seed_full_state); |
258 | |
259 | /* |
260 | * Generate better values after random number generator |
261 | * is fully initialized. |
262 | */ |
263 | static void __prandom_reseed(bool late) |
264 | { |
265 | unsigned long flags; |
266 | static bool latch = false; |
267 | static DEFINE_SPINLOCK(lock); |
268 | |
269 | /* Asking for random bytes might result in bytes getting |
270 | * moved into the nonblocking pool and thus marking it |
271 | * as initialized. In this case we would double back into |
272 | * this function and attempt to do a late reseed. |
273 | * Ignore the pointless attempt to reseed again if we're |
274 | * already waiting for bytes when the nonblocking pool |
275 | * got initialized. |
276 | */ |
277 | |
278 | /* only allow initial seeding (late == false) once */ |
279 | if (!spin_trylock_irqsave(&lock, flags)) |
280 | return; |
281 | |
282 | if (latch && !late) |
283 | goto out; |
284 | |
285 | latch = true; |
286 | prandom_seed_full_state(&net_rand_state); |
287 | out: |
288 | spin_unlock_irqrestore(&lock, flags); |
289 | } |
290 | |
291 | void prandom_reseed_late(void) |
292 | { |
293 | __prandom_reseed(true); |
294 | } |
295 | |
296 | static int __init prandom_reseed(void) |
297 | { |
298 | __prandom_reseed(false); |
299 | __prandom_start_seed_timer(); |
300 | return 0; |
301 | } |
302 | late_initcall(prandom_reseed); |
303 | |
304 | #ifdef CONFIG_RANDOM32_SELFTEST |
305 | static struct prandom_test1 { |
306 | u32 seed; |
307 | u32 result; |
308 | } test1[] = { |
309 | { 1U, 3484351685U }, |
310 | { 2U, 2623130059U }, |
311 | { 3U, 3125133893U }, |
312 | { 4U, 984847254U }, |
313 | }; |
314 | |
315 | static struct prandom_test2 { |
316 | u32 seed; |
317 | u32 iteration; |
318 | u32 result; |
319 | } test2[] = { |
320 | /* Test cases against taus113 from GSL library. */ |
321 | { 931557656U, 959U, 2975593782U }, |
322 | { 1339693295U, 876U, 3887776532U }, |
323 | { 1545556285U, 961U, 1615538833U }, |
324 | { 601730776U, 723U, 1776162651U }, |
325 | { 1027516047U, 687U, 511983079U }, |
326 | { 416526298U, 700U, 916156552U }, |
327 | { 1395522032U, 652U, 2222063676U }, |
328 | { 366221443U, 617U, 2992857763U }, |
329 | { 1539836965U, 714U, 3783265725U }, |
330 | { 556206671U, 994U, 799626459U }, |
331 | { 684907218U, 799U, 367789491U }, |
332 | { 2121230701U, 931U, 2115467001U }, |
333 | { 1668516451U, 644U, 3620590685U }, |
334 | { 768046066U, 883U, 2034077390U }, |
335 | { 1989159136U, 833U, 1195767305U }, |
336 | { 536585145U, 996U, 3577259204U }, |
337 | { 1008129373U, 642U, 1478080776U }, |
338 | { 1740775604U, 939U, 1264980372U }, |
339 | { 1967883163U, 508U, 10734624U }, |
340 | { 1923019697U, 730U, 3821419629U }, |
341 | { 442079932U, 560U, 3440032343U }, |
342 | { 1961302714U, 845U, 841962572U }, |
343 | { 2030205964U, 962U, 1325144227U }, |
344 | { 1160407529U, 507U, 240940858U }, |
345 | { 635482502U, 779U, 4200489746U }, |
346 | { 1252788931U, 699U, 867195434U }, |
347 | { 1961817131U, 719U, 668237657U }, |
348 | { 1071468216U, 983U, 917876630U }, |
349 | { 1281848367U, 932U, 1003100039U }, |
350 | { 582537119U, 780U, 1127273778U }, |
351 | { 1973672777U, 853U, 1071368872U }, |
352 | { 1896756996U, 762U, 1127851055U }, |
353 | { 847917054U, 500U, 1717499075U }, |
354 | { 1240520510U, 951U, 2849576657U }, |
355 | { 1685071682U, 567U, 1961810396U }, |
356 | { 1516232129U, 557U, 3173877U }, |
357 | { 1208118903U, 612U, 1613145022U }, |
358 | { 1817269927U, 693U, 4279122573U }, |
359 | { 1510091701U, 717U, 638191229U }, |
360 | { 365916850U, 807U, 600424314U }, |
361 | { 399324359U, 702U, 1803598116U }, |
362 | { 1318480274U, 779U, 2074237022U }, |
363 | { 697758115U, 840U, 1483639402U }, |
364 | { 1696507773U, 840U, 577415447U }, |
365 | { 2081979121U, 981U, 3041486449U }, |
366 | { 955646687U, 742U, 3846494357U }, |
367 | { 1250683506U, 749U, 836419859U }, |
368 | { 595003102U, 534U, 366794109U }, |
369 | { 47485338U, 558U, 3521120834U }, |
370 | { 619433479U, 610U, 3991783875U }, |
371 | { 704096520U, 518U, 4139493852U }, |
372 | { 1712224984U, 606U, 2393312003U }, |
373 | { 1318233152U, 922U, 3880361134U }, |
374 | { 855572992U, 761U, 1472974787U }, |
375 | { 64721421U, 703U, 683860550U }, |
376 | { 678931758U, 840U, 380616043U }, |
377 | { 692711973U, 778U, 1382361947U }, |
378 | { 677703619U, 530U, 2826914161U }, |
379 | { 92393223U, 586U, 1522128471U }, |
380 | { 1222592920U, 743U, 3466726667U }, |
381 | { 358288986U, 695U, 1091956998U }, |
382 | { 1935056945U, 958U, 514864477U }, |
383 | { 735675993U, 990U, 1294239989U }, |
384 | { 1560089402U, 897U, 2238551287U }, |
385 | { 70616361U, 829U, 22483098U }, |
386 | { 368234700U, 731U, 2913875084U }, |
387 | { 20221190U, 879U, 1564152970U }, |
388 | { 539444654U, 682U, 1835141259U }, |
389 | { 1314987297U, 840U, 1801114136U }, |
390 | { 2019295544U, 645U, 3286438930U }, |
391 | { 469023838U, 716U, 1637918202U }, |
392 | { 1843754496U, 653U, 2562092152U }, |
393 | { 400672036U, 809U, 4264212785U }, |
394 | { 404722249U, 965U, 2704116999U }, |
395 | { 600702209U, 758U, 584979986U }, |
396 | { 519953954U, 667U, 2574436237U }, |
397 | { 1658071126U, 694U, 2214569490U }, |
398 | { 420480037U, 749U, 3430010866U }, |
399 | { 690103647U, 969U, 3700758083U }, |
400 | { 1029424799U, 937U, 3787746841U }, |
401 | { 2012608669U, 506U, 3362628973U }, |
402 | { 1535432887U, 998U, 42610943U }, |
403 | { 1330635533U, 857U, 3040806504U }, |
404 | { 1223800550U, 539U, 3954229517U }, |
405 | { 1322411537U, 680U, 3223250324U }, |
406 | { 1877847898U, 945U, 2915147143U }, |
407 | { 1646356099U, 874U, 965988280U }, |
408 | { 805687536U, 744U, 4032277920U }, |
409 | { 1948093210U, 633U, 1346597684U }, |
410 | { 392609744U, 783U, 1636083295U }, |
411 | { 690241304U, 770U, 1201031298U }, |
412 | { 1360302965U, 696U, 1665394461U }, |
413 | { 1220090946U, 780U, 1316922812U }, |
414 | { 447092251U, 500U, 3438743375U }, |
415 | { 1613868791U, 592U, 828546883U }, |
416 | { 523430951U, 548U, 2552392304U }, |
417 | { 726692899U, 810U, 1656872867U }, |
418 | { 1364340021U, 836U, 3710513486U }, |
419 | { 1986257729U, 931U, 935013962U }, |
420 | { 407983964U, 921U, 728767059U }, |
421 | }; |
422 | |
423 | static void __init prandom_state_selftest(void) |
424 | { |
425 | int i, j, errors = 0, runs = 0; |
426 | bool error = false; |
427 | |
428 | for (i = 0; i < ARRAY_SIZE(test1); i++) { |
429 | struct rnd_state state; |
430 | |
431 | prandom_seed_early(&state, test1[i].seed, false); |
432 | prandom_warmup(&state); |
433 | |
434 | if (test1[i].result != prandom_u32_state(&state)) |
435 | error = true; |
436 | } |
437 | |
438 | if (error) |
439 | pr_warn("prandom: seed boundary self test failed\n"); |
440 | else |
441 | pr_info("prandom: seed boundary self test passed\n"); |
442 | |
443 | for (i = 0; i < ARRAY_SIZE(test2); i++) { |
444 | struct rnd_state state; |
445 | |
446 | prandom_seed_early(&state, test2[i].seed, false); |
447 | prandom_warmup(&state); |
448 | |
449 | for (j = 0; j < test2[i].iteration - 1; j++) |
450 | prandom_u32_state(&state); |
451 | |
452 | if (test2[i].result != prandom_u32_state(&state)) |
453 | errors++; |
454 | |
455 | runs++; |
456 | cond_resched(); |
457 | } |
458 | |
459 | if (errors) |
460 | pr_warn("prandom: %d/%d self tests failed\n", errors, runs); |
461 | else |
462 | pr_info("prandom: %d self tests passed\n", runs); |
463 | } |
464 | #endif |
465 |