1 /*
2 * Copyright 2011-2023 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10 #include <string.h>
11 #include <openssl/crypto.h>
12 #include <openssl/err.h>
13 #include <openssl/rand.h>
14 #include <openssl/evp.h>
15 #include "crypto/rand.h"
16 #include <openssl/proverr.h>
17 #include "drbg_local.h"
18 #include "internal/thread_once.h"
19 #include "crypto/cryptlib.h"
20 #include "prov/seeding.h"
21 #include "crypto/rand_pool.h"
22 #include "prov/provider_ctx.h"
23 #include "prov/providercommon.h"
24
25 /*
26 * Support framework for NIST SP 800-90A DRBG
27 *
28 * See manual page PROV_DRBG(7) for a general overview.
29 *
30 * The OpenSSL model is to have new and free functions, and that new
31 * does all initialization. That is not the NIST model, which has
32 * instantiation and un-instantiate, and re-use within a new/free
33 * lifecycle. (No doubt this comes from the desire to support hardware
34 * DRBG, where allocation of resources on something like an HSM is
35 * a much bigger deal than just re-setting an allocated resource.)
36 */
37
38 /* NIST SP 800-90A DRBG recommends the use of a personalization string. */
39 static const char ossl_pers_string[] = DRBG_DEFAULT_PERS_STRING;
40
41 static const OSSL_DISPATCH *find_call(const OSSL_DISPATCH *dispatch,
42 int function);
43
44 static int rand_drbg_restart(PROV_DRBG *drbg);
45
ossl_drbg_lock(void * vctx)46 int ossl_drbg_lock(void *vctx)
47 {
48 PROV_DRBG *drbg = vctx;
49
50 if (drbg == NULL || drbg->lock == NULL)
51 return 1;
52 return CRYPTO_THREAD_write_lock(drbg->lock);
53 }
54
ossl_drbg_unlock(void * vctx)55 void ossl_drbg_unlock(void *vctx)
56 {
57 PROV_DRBG *drbg = vctx;
58
59 if (drbg != NULL && drbg->lock != NULL)
60 CRYPTO_THREAD_unlock(drbg->lock);
61 }
62
ossl_drbg_lock_parent(PROV_DRBG * drbg)63 static int ossl_drbg_lock_parent(PROV_DRBG *drbg)
64 {
65 void *parent = drbg->parent;
66
67 if (parent != NULL
68 && drbg->parent_lock != NULL
69 && !drbg->parent_lock(parent)) {
70 ERR_raise(ERR_LIB_PROV, PROV_R_PARENT_LOCKING_NOT_ENABLED);
71 return 0;
72 }
73 return 1;
74 }
75
ossl_drbg_unlock_parent(PROV_DRBG * drbg)76 static void ossl_drbg_unlock_parent(PROV_DRBG *drbg)
77 {
78 void *parent = drbg->parent;
79
80 if (parent != NULL && drbg->parent_unlock != NULL)
81 drbg->parent_unlock(parent);
82 }
83
get_parent_strength(PROV_DRBG * drbg,unsigned int * str)84 static int get_parent_strength(PROV_DRBG *drbg, unsigned int *str)
85 {
86 OSSL_PARAM params[2] = { OSSL_PARAM_END, OSSL_PARAM_END };
87 void *parent = drbg->parent;
88 int res;
89
90 if (drbg->parent_get_ctx_params == NULL) {
91 ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_GET_PARENT_STRENGTH);
92 return 0;
93 }
94
95 *params = OSSL_PARAM_construct_uint(OSSL_RAND_PARAM_STRENGTH, str);
96 if (!ossl_drbg_lock_parent(drbg)) {
97 ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_LOCK_PARENT);
98 return 0;
99 }
100 res = drbg->parent_get_ctx_params(parent, params);
101 ossl_drbg_unlock_parent(drbg);
102 if (!res) {
103 ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_GET_PARENT_STRENGTH);
104 return 0;
105 }
106 return 1;
107 }
108
get_parent_reseed_count(PROV_DRBG * drbg)109 static unsigned int get_parent_reseed_count(PROV_DRBG *drbg)
110 {
111 OSSL_PARAM params[2] = { OSSL_PARAM_END, OSSL_PARAM_END };
112 void *parent = drbg->parent;
113 unsigned int r = 0;
114
115 *params = OSSL_PARAM_construct_uint(OSSL_DRBG_PARAM_RESEED_COUNTER, &r);
116 if (!ossl_drbg_lock_parent(drbg)) {
117 ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_LOCK_PARENT);
118 goto err;
119 }
120 if (!drbg->parent_get_ctx_params(parent, params))
121 r = 0;
122 ossl_drbg_unlock_parent(drbg);
123 return r;
124
125 err:
126 r = tsan_load(&drbg->reseed_counter) - 2;
127 if (r == 0)
128 r = UINT_MAX;
129 return r;
130 }
131
132 /*
133 * Implements the get_entropy() callback
134 *
135 * If the DRBG has a parent, then the required amount of entropy input
136 * is fetched using the parent's ossl_prov_drbg_generate().
137 *
138 * Otherwise, the entropy is polled from the system entropy sources
139 * using ossl_pool_acquire_entropy().
140 *
141 * If a random pool has been added to the DRBG using RAND_add(), then
142 * its entropy will be used up first.
143 */
ossl_drbg_get_seed(void * vdrbg,unsigned char ** pout,int entropy,size_t min_len,size_t max_len,int prediction_resistance,const unsigned char * adin,size_t adin_len)144 size_t ossl_drbg_get_seed(void *vdrbg, unsigned char **pout,
145 int entropy, size_t min_len,
146 size_t max_len, int prediction_resistance,
147 const unsigned char *adin, size_t adin_len)
148 {
149 PROV_DRBG *drbg = (PROV_DRBG *)vdrbg;
150 size_t bytes_needed;
151 unsigned char *buffer;
152
153 /* Figure out how many bytes we need */
154 bytes_needed = entropy >= 0 ? (entropy + 7) / 8 : 0;
155 if (bytes_needed < min_len)
156 bytes_needed = min_len;
157 if (bytes_needed > max_len)
158 bytes_needed = max_len;
159
160 /* Allocate storage */
161 buffer = OPENSSL_secure_malloc(bytes_needed);
162 if (buffer == NULL) {
163 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
164 return 0;
165 }
166
167 /*
168 * Get random data. Include our DRBG address as
169 * additional input, in order to provide a distinction between
170 * different DRBG child instances.
171 *
172 * Note: using the sizeof() operator on a pointer triggers
173 * a warning in some static code analyzers, but it's
174 * intentional and correct here.
175 */
176 if (!ossl_prov_drbg_generate(drbg, buffer, bytes_needed,
177 drbg->strength, prediction_resistance,
178 (unsigned char *)&drbg, sizeof(drbg))) {
179 OPENSSL_secure_clear_free(buffer, bytes_needed);
180 ERR_raise(ERR_LIB_PROV, PROV_R_GENERATE_ERROR);
181 return 0;
182 }
183 *pout = buffer;
184 return bytes_needed;
185 }
186
187 /* Implements the cleanup_entropy() callback */
ossl_drbg_clear_seed(ossl_unused void * vdrbg,unsigned char * out,size_t outlen)188 void ossl_drbg_clear_seed(ossl_unused void *vdrbg,
189 unsigned char *out, size_t outlen)
190 {
191 OPENSSL_secure_clear_free(out, outlen);
192 }
193
get_entropy(PROV_DRBG * drbg,unsigned char ** pout,int entropy,size_t min_len,size_t max_len,int prediction_resistance)194 static size_t get_entropy(PROV_DRBG *drbg, unsigned char **pout, int entropy,
195 size_t min_len, size_t max_len,
196 int prediction_resistance)
197 {
198 size_t bytes;
199 unsigned int p_str;
200
201 if (drbg->parent == NULL)
202 #ifdef FIPS_MODULE
203 return ossl_crngt_get_entropy(drbg, pout, entropy, min_len, max_len,
204 prediction_resistance);
205 #else
206 return ossl_prov_get_entropy(drbg->provctx, pout, entropy, min_len,
207 max_len);
208 #endif
209
210 if (drbg->parent_get_seed == NULL) {
211 ERR_raise(ERR_LIB_PROV, PROV_R_PARENT_CANNOT_SUPPLY_ENTROPY_SEED);
212 return 0;
213 }
214 if (!get_parent_strength(drbg, &p_str))
215 return 0;
216 if (drbg->strength > p_str) {
217 /*
218 * We currently don't support the algorithm from NIST SP 800-90C
219 * 10.1.2 to use a weaker DRBG as source
220 */
221 ERR_raise(ERR_LIB_PROV, PROV_R_PARENT_STRENGTH_TOO_WEAK);
222 return 0;
223 }
224
225 /*
226 * Our lock is already held, but we need to lock our parent before
227 * generating bits from it. Note: taking the lock will be a no-op
228 * if locking is not required (while drbg->parent->lock == NULL).
229 */
230 if (!ossl_drbg_lock_parent(drbg))
231 return 0;
232 /*
233 * Get random data from parent. Include our DRBG address as
234 * additional input, in order to provide a distinction between
235 * different DRBG child instances.
236 *
237 * Note: using the sizeof() operator on a pointer triggers
238 * a warning in some static code analyzers, but it's
239 * intentional and correct here.
240 */
241 bytes = drbg->parent_get_seed(drbg->parent, pout, drbg->strength,
242 min_len, max_len, prediction_resistance,
243 (unsigned char *)&drbg, sizeof(drbg));
244 ossl_drbg_unlock_parent(drbg);
245 return bytes;
246 }
247
cleanup_entropy(PROV_DRBG * drbg,unsigned char * out,size_t outlen)248 static void cleanup_entropy(PROV_DRBG *drbg, unsigned char *out, size_t outlen)
249 {
250 if (drbg->parent == NULL) {
251 #ifdef FIPS_MODULE
252 ossl_crngt_cleanup_entropy(drbg, out, outlen);
253 #else
254 ossl_prov_cleanup_entropy(drbg->provctx, out, outlen);
255 #endif
256 } else if (drbg->parent_clear_seed != NULL) {
257 if (!ossl_drbg_lock_parent(drbg))
258 return;
259 drbg->parent_clear_seed(drbg->parent, out, outlen);
260 ossl_drbg_unlock_parent(drbg);
261 }
262 }
263
264 #ifndef PROV_RAND_GET_RANDOM_NONCE
265 typedef struct prov_drbg_nonce_global_st {
266 CRYPTO_RWLOCK *rand_nonce_lock;
267 int rand_nonce_count;
268 } PROV_DRBG_NONCE_GLOBAL;
269
270 /*
271 * drbg_ossl_ctx_new() calls drgb_setup() which calls rand_drbg_get_nonce()
272 * which needs to get the rand_nonce_lock out of the OSSL_LIB_CTX...but since
273 * drbg_ossl_ctx_new() hasn't finished running yet we need the rand_nonce_lock
274 * to be in a different global data object. Otherwise we will go into an
275 * infinite recursion loop.
276 */
prov_drbg_nonce_ossl_ctx_new(OSSL_LIB_CTX * libctx)277 static void *prov_drbg_nonce_ossl_ctx_new(OSSL_LIB_CTX *libctx)
278 {
279 PROV_DRBG_NONCE_GLOBAL *dngbl = OPENSSL_zalloc(sizeof(*dngbl));
280
281 if (dngbl == NULL)
282 return NULL;
283
284 dngbl->rand_nonce_lock = CRYPTO_THREAD_lock_new();
285 if (dngbl->rand_nonce_lock == NULL) {
286 OPENSSL_free(dngbl);
287 return NULL;
288 }
289
290 return dngbl;
291 }
292
prov_drbg_nonce_ossl_ctx_free(void * vdngbl)293 static void prov_drbg_nonce_ossl_ctx_free(void *vdngbl)
294 {
295 PROV_DRBG_NONCE_GLOBAL *dngbl = vdngbl;
296
297 if (dngbl == NULL)
298 return;
299
300 CRYPTO_THREAD_lock_free(dngbl->rand_nonce_lock);
301
302 OPENSSL_free(dngbl);
303 }
304
305 static const OSSL_LIB_CTX_METHOD drbg_nonce_ossl_ctx_method = {
306 OSSL_LIB_CTX_METHOD_DEFAULT_PRIORITY,
307 prov_drbg_nonce_ossl_ctx_new,
308 prov_drbg_nonce_ossl_ctx_free,
309 };
310
311 /* Get a nonce from the operating system */
prov_drbg_get_nonce(PROV_DRBG * drbg,unsigned char ** pout,size_t min_len,size_t max_len)312 static size_t prov_drbg_get_nonce(PROV_DRBG *drbg, unsigned char **pout,
313 size_t min_len, size_t max_len)
314 {
315 size_t ret = 0, n;
316 unsigned char *buf = NULL;
317 OSSL_LIB_CTX *libctx = ossl_prov_ctx_get0_libctx(drbg->provctx);
318 PROV_DRBG_NONCE_GLOBAL *dngbl
319 = ossl_lib_ctx_get_data(libctx, OSSL_LIB_CTX_DRBG_NONCE_INDEX,
320 &drbg_nonce_ossl_ctx_method);
321 struct {
322 void *drbg;
323 int count;
324 } data;
325
326 if (dngbl == NULL)
327 return 0;
328
329 if (drbg->parent != NULL && drbg->parent_nonce != NULL) {
330 n = drbg->parent_nonce(drbg->parent, NULL, 0, drbg->min_noncelen,
331 drbg->max_noncelen);
332 if (n > 0 && (buf = OPENSSL_malloc(n)) != NULL) {
333 ret = drbg->parent_nonce(drbg->parent, buf, 0,
334 drbg->min_noncelen, drbg->max_noncelen);
335 if (ret == n) {
336 *pout = buf;
337 return ret;
338 }
339 OPENSSL_free(buf);
340 }
341 }
342
343 /* Use the built in nonce source plus some of our specifics */
344 memset(&data, 0, sizeof(data));
345 data.drbg = drbg;
346 CRYPTO_atomic_add(&dngbl->rand_nonce_count, 1, &data.count,
347 dngbl->rand_nonce_lock);
348 return ossl_prov_get_nonce(drbg->provctx, pout, min_len, max_len,
349 &data, sizeof(data));
350 }
351 #endif /* PROV_RAND_GET_RANDOM_NONCE */
352
353 /*
354 * Instantiate |drbg|, after it has been initialized. Use |pers| and
355 * |perslen| as prediction-resistance input.
356 *
357 * Requires that drbg->lock is already locked for write, if non-null.
358 *
359 * Returns 1 on success, 0 on failure.
360 */
ossl_prov_drbg_instantiate(PROV_DRBG * drbg,unsigned int strength,int prediction_resistance,const unsigned char * pers,size_t perslen)361 int ossl_prov_drbg_instantiate(PROV_DRBG *drbg, unsigned int strength,
362 int prediction_resistance,
363 const unsigned char *pers, size_t perslen)
364 {
365 unsigned char *nonce = NULL, *entropy = NULL;
366 size_t noncelen = 0, entropylen = 0;
367 size_t min_entropy, min_entropylen, max_entropylen;
368
369 if (strength > drbg->strength) {
370 ERR_raise(ERR_LIB_PROV, PROV_R_INSUFFICIENT_DRBG_STRENGTH);
371 goto end;
372 }
373 min_entropy = drbg->strength;
374 min_entropylen = drbg->min_entropylen;
375 max_entropylen = drbg->max_entropylen;
376
377 if (pers == NULL) {
378 pers = (const unsigned char *)ossl_pers_string;
379 perslen = sizeof(ossl_pers_string);
380 }
381 if (perslen > drbg->max_perslen) {
382 ERR_raise(ERR_LIB_PROV, PROV_R_PERSONALISATION_STRING_TOO_LONG);
383 goto end;
384 }
385
386 if (drbg->state != EVP_RAND_STATE_UNINITIALISED) {
387 if (drbg->state == EVP_RAND_STATE_ERROR)
388 ERR_raise(ERR_LIB_PROV, PROV_R_IN_ERROR_STATE);
389 else
390 ERR_raise(ERR_LIB_PROV, PROV_R_ALREADY_INSTANTIATED);
391 goto end;
392 }
393
394 drbg->state = EVP_RAND_STATE_ERROR;
395
396 if (drbg->min_noncelen > 0) {
397 if (drbg->parent_nonce != NULL) {
398 noncelen = drbg->parent_nonce(drbg->parent, NULL, drbg->strength,
399 drbg->min_noncelen,
400 drbg->max_noncelen);
401 if (noncelen == 0) {
402 ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_NONCE);
403 goto end;
404 }
405 nonce = OPENSSL_malloc(noncelen);
406 if (nonce == NULL) {
407 ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_NONCE);
408 goto end;
409 }
410 if (noncelen != drbg->parent_nonce(drbg->parent, nonce,
411 drbg->strength,
412 drbg->min_noncelen,
413 drbg->max_noncelen)) {
414 ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_NONCE);
415 goto end;
416 }
417 #ifndef PROV_RAND_GET_RANDOM_NONCE
418 } else if (drbg->parent != NULL) {
419 #endif
420 /*
421 * NIST SP800-90Ar1 section 9.1 says you can combine getting
422 * the entropy and nonce in 1 call by increasing the entropy
423 * with 50% and increasing the minimum length to accommodate
424 * the length of the nonce. We do this in case a nonce is
425 * required and there is no parental nonce capability.
426 */
427 min_entropy += drbg->strength / 2;
428 min_entropylen += drbg->min_noncelen;
429 max_entropylen += drbg->max_noncelen;
430 }
431 #ifndef PROV_RAND_GET_RANDOM_NONCE
432 else { /* parent == NULL */
433 noncelen = prov_drbg_get_nonce(drbg, &nonce, drbg->min_noncelen,
434 drbg->max_noncelen);
435 if (noncelen < drbg->min_noncelen
436 || noncelen > drbg->max_noncelen) {
437 ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_NONCE);
438 goto end;
439 }
440 }
441 #endif
442 }
443
444 drbg->reseed_next_counter = tsan_load(&drbg->reseed_counter);
445 if (drbg->reseed_next_counter) {
446 drbg->reseed_next_counter++;
447 if (!drbg->reseed_next_counter)
448 drbg->reseed_next_counter = 1;
449 }
450
451 entropylen = get_entropy(drbg, &entropy, min_entropy,
452 min_entropylen, max_entropylen,
453 prediction_resistance);
454 if (entropylen < min_entropylen
455 || entropylen > max_entropylen) {
456 ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_ENTROPY);
457 goto end;
458 }
459
460 if (!drbg->instantiate(drbg, entropy, entropylen, nonce, noncelen,
461 pers, perslen)) {
462 cleanup_entropy(drbg, entropy, entropylen);
463 ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_INSTANTIATING_DRBG);
464 goto end;
465 }
466 cleanup_entropy(drbg, entropy, entropylen);
467
468 drbg->state = EVP_RAND_STATE_READY;
469 drbg->generate_counter = 1;
470 drbg->reseed_time = time(NULL);
471 tsan_store(&drbg->reseed_counter, drbg->reseed_next_counter);
472
473 end:
474 if (nonce != NULL)
475 ossl_prov_cleanup_nonce(drbg->provctx, nonce, noncelen);
476 if (drbg->state == EVP_RAND_STATE_READY)
477 return 1;
478 return 0;
479 }
480
481 /*
482 * Uninstantiate |drbg|. Must be instantiated before it can be used.
483 *
484 * Requires that drbg->lock is already locked for write, if non-null.
485 *
486 * Returns 1 on success, 0 on failure.
487 */
ossl_prov_drbg_uninstantiate(PROV_DRBG * drbg)488 int ossl_prov_drbg_uninstantiate(PROV_DRBG *drbg)
489 {
490 drbg->state = EVP_RAND_STATE_UNINITIALISED;
491 return 1;
492 }
493
494 /*
495 * Reseed |drbg|, mixing in the specified data
496 *
497 * Requires that drbg->lock is already locked for write, if non-null.
498 *
499 * Returns 1 on success, 0 on failure.
500 */
ossl_prov_drbg_reseed(PROV_DRBG * drbg,int prediction_resistance,const unsigned char * ent,size_t ent_len,const unsigned char * adin,size_t adinlen)501 int ossl_prov_drbg_reseed(PROV_DRBG *drbg, int prediction_resistance,
502 const unsigned char *ent, size_t ent_len,
503 const unsigned char *adin, size_t adinlen)
504 {
505 unsigned char *entropy = NULL;
506 size_t entropylen = 0;
507
508 if (!ossl_prov_is_running())
509 return 0;
510
511 if (drbg->state != EVP_RAND_STATE_READY) {
512 /* try to recover from previous errors */
513 rand_drbg_restart(drbg);
514
515 if (drbg->state == EVP_RAND_STATE_ERROR) {
516 ERR_raise(ERR_LIB_PROV, PROV_R_IN_ERROR_STATE);
517 return 0;
518 }
519 if (drbg->state == EVP_RAND_STATE_UNINITIALISED) {
520 ERR_raise(ERR_LIB_PROV, PROV_R_NOT_INSTANTIATED);
521 return 0;
522 }
523 }
524
525 if (ent != NULL) {
526 if (ent_len < drbg->min_entropylen) {
527 ERR_raise(ERR_LIB_RAND, RAND_R_ENTROPY_OUT_OF_RANGE);
528 drbg->state = EVP_RAND_STATE_ERROR;
529 return 0;
530 }
531 if (ent_len > drbg->max_entropylen) {
532 ERR_raise(ERR_LIB_RAND, RAND_R_ENTROPY_INPUT_TOO_LONG);
533 drbg->state = EVP_RAND_STATE_ERROR;
534 return 0;
535 }
536 }
537
538 if (adin == NULL) {
539 adinlen = 0;
540 } else if (adinlen > drbg->max_adinlen) {
541 ERR_raise(ERR_LIB_PROV, PROV_R_ADDITIONAL_INPUT_TOO_LONG);
542 return 0;
543 }
544
545 drbg->state = EVP_RAND_STATE_ERROR;
546
547 drbg->reseed_next_counter = tsan_load(&drbg->reseed_counter);
548 if (drbg->reseed_next_counter) {
549 drbg->reseed_next_counter++;
550 if (!drbg->reseed_next_counter)
551 drbg->reseed_next_counter = 1;
552 }
553
554 if (ent != NULL) {
555 #ifdef FIPS_MODULE
556 /*
557 * NIST SP-800-90A mandates that entropy *shall not* be provided
558 * by the consuming application. Instead the data is added as additional
559 * input.
560 *
561 * (NIST SP-800-90Ar1, Sections 9.1 and 9.2)
562 */
563 if (!drbg->reseed(drbg, NULL, 0, ent, ent_len)) {
564 ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_RESEED);
565 return 0;
566 }
567 #else
568 if (!drbg->reseed(drbg, ent, ent_len, adin, adinlen)) {
569 ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_RESEED);
570 return 0;
571 }
572 /* There isn't much point adding the same additional input twice */
573 adin = NULL;
574 adinlen = 0;
575 #endif
576 }
577
578 /* Reseed using our sources in addition */
579 entropylen = get_entropy(drbg, &entropy, drbg->strength,
580 drbg->min_entropylen, drbg->max_entropylen,
581 prediction_resistance);
582 if (entropylen < drbg->min_entropylen
583 || entropylen > drbg->max_entropylen) {
584 ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_ENTROPY);
585 goto end;
586 }
587
588 if (!drbg->reseed(drbg, entropy, entropylen, adin, adinlen))
589 goto end;
590
591 drbg->state = EVP_RAND_STATE_READY;
592 drbg->generate_counter = 1;
593 drbg->reseed_time = time(NULL);
594 tsan_store(&drbg->reseed_counter, drbg->reseed_next_counter);
595 if (drbg->parent != NULL)
596 drbg->parent_reseed_counter = get_parent_reseed_count(drbg);
597
598 end:
599 cleanup_entropy(drbg, entropy, entropylen);
600 if (drbg->state == EVP_RAND_STATE_READY)
601 return 1;
602 return 0;
603 }
604
605 /*
606 * Generate |outlen| bytes into the buffer at |out|. Reseed if we need
607 * to or if |prediction_resistance| is set. Additional input can be
608 * sent in |adin| and |adinlen|.
609 *
610 * Requires that drbg->lock is already locked for write, if non-null.
611 *
612 * Returns 1 on success, 0 on failure.
613 *
614 */
ossl_prov_drbg_generate(PROV_DRBG * drbg,unsigned char * out,size_t outlen,unsigned int strength,int prediction_resistance,const unsigned char * adin,size_t adinlen)615 int ossl_prov_drbg_generate(PROV_DRBG *drbg, unsigned char *out, size_t outlen,
616 unsigned int strength, int prediction_resistance,
617 const unsigned char *adin, size_t adinlen)
618 {
619 int fork_id;
620 int reseed_required = 0;
621
622 if (!ossl_prov_is_running())
623 return 0;
624
625 if (drbg->state != EVP_RAND_STATE_READY) {
626 /* try to recover from previous errors */
627 rand_drbg_restart(drbg);
628
629 if (drbg->state == EVP_RAND_STATE_ERROR) {
630 ERR_raise(ERR_LIB_PROV, PROV_R_IN_ERROR_STATE);
631 return 0;
632 }
633 if (drbg->state == EVP_RAND_STATE_UNINITIALISED) {
634 ERR_raise(ERR_LIB_PROV, PROV_R_NOT_INSTANTIATED);
635 return 0;
636 }
637 }
638 if (strength > drbg->strength) {
639 ERR_raise(ERR_LIB_PROV, PROV_R_INSUFFICIENT_DRBG_STRENGTH);
640 return 0;
641 }
642
643 if (outlen > drbg->max_request) {
644 ERR_raise(ERR_LIB_PROV, PROV_R_REQUEST_TOO_LARGE_FOR_DRBG);
645 return 0;
646 }
647 if (adinlen > drbg->max_adinlen) {
648 ERR_raise(ERR_LIB_PROV, PROV_R_ADDITIONAL_INPUT_TOO_LONG);
649 return 0;
650 }
651
652 fork_id = openssl_get_fork_id();
653
654 if (drbg->fork_id != fork_id) {
655 drbg->fork_id = fork_id;
656 reseed_required = 1;
657 }
658
659 if (drbg->reseed_interval > 0) {
660 if (drbg->generate_counter >= drbg->reseed_interval)
661 reseed_required = 1;
662 }
663 if (drbg->reseed_time_interval > 0) {
664 time_t now = time(NULL);
665 if (now < drbg->reseed_time
666 || now - drbg->reseed_time >= drbg->reseed_time_interval)
667 reseed_required = 1;
668 }
669 if (drbg->parent != NULL
670 && get_parent_reseed_count(drbg) != drbg->parent_reseed_counter)
671 reseed_required = 1;
672
673 if (reseed_required || prediction_resistance) {
674 if (!ossl_prov_drbg_reseed(drbg, prediction_resistance, NULL, 0,
675 adin, adinlen)) {
676 ERR_raise(ERR_LIB_PROV, PROV_R_RESEED_ERROR);
677 return 0;
678 }
679 adin = NULL;
680 adinlen = 0;
681 }
682
683 if (!drbg->generate(drbg, out, outlen, adin, adinlen)) {
684 drbg->state = EVP_RAND_STATE_ERROR;
685 ERR_raise(ERR_LIB_PROV, PROV_R_GENERATE_ERROR);
686 return 0;
687 }
688
689 drbg->generate_counter++;
690
691 return 1;
692 }
693
694 /*
695 * Restart |drbg|, using the specified entropy or additional input
696 *
697 * Tries its best to get the drbg instantiated by all means,
698 * regardless of its current state.
699 *
700 * Optionally, a |buffer| of |len| random bytes can be passed,
701 * which is assumed to contain at least |entropy| bits of entropy.
702 *
703 * If |entropy| > 0, the buffer content is used as entropy input.
704 *
705 * If |entropy| == 0, the buffer content is used as additional input
706 *
707 * Returns 1 on success, 0 on failure.
708 *
709 * This function is used internally only.
710 */
rand_drbg_restart(PROV_DRBG * drbg)711 static int rand_drbg_restart(PROV_DRBG *drbg)
712 {
713 /* repair error state */
714 if (drbg->state == EVP_RAND_STATE_ERROR)
715 drbg->uninstantiate(drbg);
716
717 /* repair uninitialized state */
718 if (drbg->state == EVP_RAND_STATE_UNINITIALISED)
719 /* reinstantiate drbg */
720 ossl_prov_drbg_instantiate(drbg, drbg->strength, 0, NULL, 0);
721
722 return drbg->state == EVP_RAND_STATE_READY;
723 }
724
725 /* Provider support from here down */
find_call(const OSSL_DISPATCH * dispatch,int function)726 static const OSSL_DISPATCH *find_call(const OSSL_DISPATCH *dispatch,
727 int function)
728 {
729 if (dispatch != NULL)
730 while (dispatch->function_id != 0) {
731 if (dispatch->function_id == function)
732 return dispatch;
733 dispatch++;
734 }
735 return NULL;
736 }
737
ossl_drbg_enable_locking(void * vctx)738 int ossl_drbg_enable_locking(void *vctx)
739 {
740 PROV_DRBG *drbg = vctx;
741
742 if (drbg != NULL && drbg->lock == NULL) {
743 if (drbg->parent_enable_locking != NULL)
744 if (!drbg->parent_enable_locking(drbg->parent)) {
745 ERR_raise(ERR_LIB_PROV, PROV_R_PARENT_LOCKING_NOT_ENABLED);
746 return 0;
747 }
748 drbg->lock = CRYPTO_THREAD_lock_new();
749 if (drbg->lock == NULL) {
750 ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_CREATE_LOCK);
751 return 0;
752 }
753 }
754 return 1;
755 }
756
757 /*
758 * Allocate memory and initialize a new DRBG. The DRBG is allocated on
759 * the secure heap if |secure| is nonzero and the secure heap is enabled.
760 * The |parent|, if not NULL, will be used as random source for reseeding.
761 * This also requires the parent's provider context and the parent's lock.
762 *
763 * Returns a pointer to the new DRBG instance on success, NULL on failure.
764 */
ossl_rand_drbg_new(void * provctx,void * parent,const OSSL_DISPATCH * p_dispatch,int (* dnew)(PROV_DRBG * ctx),int (* instantiate)(PROV_DRBG * drbg,const unsigned char * entropy,size_t entropylen,const unsigned char * nonce,size_t noncelen,const unsigned char * pers,size_t perslen),int (* uninstantiate)(PROV_DRBG * ctx),int (* reseed)(PROV_DRBG * drbg,const unsigned char * ent,size_t ent_len,const unsigned char * adin,size_t adin_len),int (* generate)(PROV_DRBG *,unsigned char * out,size_t outlen,const unsigned char * adin,size_t adin_len))765 PROV_DRBG *ossl_rand_drbg_new
766 (void *provctx, void *parent, const OSSL_DISPATCH *p_dispatch,
767 int (*dnew)(PROV_DRBG *ctx),
768 int (*instantiate)(PROV_DRBG *drbg,
769 const unsigned char *entropy, size_t entropylen,
770 const unsigned char *nonce, size_t noncelen,
771 const unsigned char *pers, size_t perslen),
772 int (*uninstantiate)(PROV_DRBG *ctx),
773 int (*reseed)(PROV_DRBG *drbg, const unsigned char *ent, size_t ent_len,
774 const unsigned char *adin, size_t adin_len),
775 int (*generate)(PROV_DRBG *, unsigned char *out, size_t outlen,
776 const unsigned char *adin, size_t adin_len))
777 {
778 PROV_DRBG *drbg;
779 unsigned int p_str;
780 const OSSL_DISPATCH *pfunc;
781
782 if (!ossl_prov_is_running())
783 return NULL;
784
785 drbg = OPENSSL_zalloc(sizeof(*drbg));
786 if (drbg == NULL) {
787 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
788 return NULL;
789 }
790
791 drbg->provctx = provctx;
792 drbg->instantiate = instantiate;
793 drbg->uninstantiate = uninstantiate;
794 drbg->reseed = reseed;
795 drbg->generate = generate;
796 drbg->fork_id = openssl_get_fork_id();
797
798 /* Extract parent's functions */
799 drbg->parent = parent;
800 if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_ENABLE_LOCKING)) != NULL)
801 drbg->parent_enable_locking = OSSL_FUNC_rand_enable_locking(pfunc);
802 if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_LOCK)) != NULL)
803 drbg->parent_lock = OSSL_FUNC_rand_lock(pfunc);
804 if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_UNLOCK)) != NULL)
805 drbg->parent_unlock = OSSL_FUNC_rand_unlock(pfunc);
806 if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_GET_CTX_PARAMS)) != NULL)
807 drbg->parent_get_ctx_params = OSSL_FUNC_rand_get_ctx_params(pfunc);
808 if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_NONCE)) != NULL)
809 drbg->parent_nonce = OSSL_FUNC_rand_nonce(pfunc);
810 if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_GET_SEED)) != NULL)
811 drbg->parent_get_seed = OSSL_FUNC_rand_get_seed(pfunc);
812 if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_CLEAR_SEED)) != NULL)
813 drbg->parent_clear_seed = OSSL_FUNC_rand_clear_seed(pfunc);
814
815 /* Set some default maximums up */
816 drbg->max_entropylen = DRBG_MAX_LENGTH;
817 drbg->max_noncelen = DRBG_MAX_LENGTH;
818 drbg->max_perslen = DRBG_MAX_LENGTH;
819 drbg->max_adinlen = DRBG_MAX_LENGTH;
820 drbg->generate_counter = 1;
821 drbg->reseed_counter = 1;
822 drbg->reseed_interval = RESEED_INTERVAL;
823 drbg->reseed_time_interval = TIME_INTERVAL;
824
825 if (!dnew(drbg))
826 goto err;
827
828 if (parent != NULL) {
829 if (!get_parent_strength(drbg, &p_str))
830 goto err;
831 if (drbg->strength > p_str) {
832 /*
833 * We currently don't support the algorithm from NIST SP 800-90C
834 * 10.1.2 to use a weaker DRBG as source
835 */
836 ERR_raise(ERR_LIB_PROV, PROV_R_PARENT_STRENGTH_TOO_WEAK);
837 goto err;
838 }
839 }
840 #ifdef TSAN_REQUIRES_LOCKING
841 if (!ossl_drbg_enable_locking(drbg))
842 goto err;
843 #endif
844 return drbg;
845
846 err:
847 ossl_rand_drbg_free(drbg);
848 return NULL;
849 }
850
ossl_rand_drbg_free(PROV_DRBG * drbg)851 void ossl_rand_drbg_free(PROV_DRBG *drbg)
852 {
853 if (drbg == NULL)
854 return;
855
856 CRYPTO_THREAD_lock_free(drbg->lock);
857 OPENSSL_free(drbg);
858 }
859
ossl_drbg_get_ctx_params(PROV_DRBG * drbg,OSSL_PARAM params[])860 int ossl_drbg_get_ctx_params(PROV_DRBG *drbg, OSSL_PARAM params[])
861 {
862 OSSL_PARAM *p;
863
864 p = OSSL_PARAM_locate(params, OSSL_RAND_PARAM_STATE);
865 if (p != NULL && !OSSL_PARAM_set_int(p, drbg->state))
866 return 0;
867
868 p = OSSL_PARAM_locate(params, OSSL_RAND_PARAM_STRENGTH);
869 if (p != NULL && !OSSL_PARAM_set_int(p, drbg->strength))
870 return 0;
871
872 p = OSSL_PARAM_locate(params, OSSL_RAND_PARAM_MAX_REQUEST);
873 if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->max_request))
874 return 0;
875
876 p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MIN_ENTROPYLEN);
877 if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->min_entropylen))
878 return 0;
879
880 p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MAX_ENTROPYLEN);
881 if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->max_entropylen))
882 return 0;
883
884 p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MIN_NONCELEN);
885 if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->min_noncelen))
886 return 0;
887
888 p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MAX_NONCELEN);
889 if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->max_noncelen))
890 return 0;
891
892 p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MAX_PERSLEN);
893 if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->max_perslen))
894 return 0;
895
896 p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MAX_ADINLEN);
897 if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->max_adinlen))
898 return 0;
899
900 p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_RESEED_REQUESTS);
901 if (p != NULL && !OSSL_PARAM_set_uint(p, drbg->reseed_interval))
902 return 0;
903
904 p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_RESEED_TIME);
905 if (p != NULL && !OSSL_PARAM_set_time_t(p, drbg->reseed_time))
906 return 0;
907
908 p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL);
909 if (p != NULL && !OSSL_PARAM_set_time_t(p, drbg->reseed_time_interval))
910 return 0;
911
912 p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_RESEED_COUNTER);
913 if (p != NULL
914 && !OSSL_PARAM_set_uint(p, tsan_load(&drbg->reseed_counter)))
915 return 0;
916 return 1;
917 }
918
ossl_drbg_set_ctx_params(PROV_DRBG * drbg,const OSSL_PARAM params[])919 int ossl_drbg_set_ctx_params(PROV_DRBG *drbg, const OSSL_PARAM params[])
920 {
921 const OSSL_PARAM *p;
922
923 if (params == NULL)
924 return 1;
925
926 p = OSSL_PARAM_locate_const(params, OSSL_DRBG_PARAM_RESEED_REQUESTS);
927 if (p != NULL && !OSSL_PARAM_get_uint(p, &drbg->reseed_interval))
928 return 0;
929
930 p = OSSL_PARAM_locate_const(params, OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL);
931 if (p != NULL && !OSSL_PARAM_get_time_t(p, &drbg->reseed_time_interval))
932 return 0;
933 return 1;
934 }
935