1/*
2 * Copyright 2011-2020 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the OpenSSL license (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 "rand_local.h"
15#include "internal/thread_once.h"
16#include "crypto/rand.h"
17#include "crypto/cryptlib.h"
18
19/*
20 * Support framework for NIST SP 800-90A DRBG
21 *
22 * See manual page RAND_DRBG(7) for a general overview.
23 *
24 * The OpenSSL model is to have new and free functions, and that new
25 * does all initialization.  That is not the NIST model, which has
26 * instantiation and un-instantiate, and re-use within a new/free
27 * lifecycle.  (No doubt this comes from the desire to support hardware
28 * DRBG, where allocation of resources on something like an HSM is
29 * a much bigger deal than just re-setting an allocated resource.)
30 */
31
32/*
33 * The three shared DRBG instances
34 *
35 * There are three shared DRBG instances: <master>, <public>, and <private>.
36 */
37
38/*
39 * The <master> DRBG
40 *
41 * Not used directly by the application, only for reseeding the two other
42 * DRBGs. It reseeds itself by pulling either randomness from os entropy
43 * sources or by consuming randomness which was added by RAND_add().
44 *
45 * The <master> DRBG is a global instance which is accessed concurrently by
46 * all threads. The necessary locking is managed automatically by its child
47 * DRBG instances during reseeding.
48 */
49static RAND_DRBG *master_drbg;
50/*
51 * The <public> DRBG
52 *
53 * Used by default for generating random bytes using RAND_bytes().
54 *
55 * The <public> DRBG is thread-local, i.e., there is one instance per thread.
56 */
57static CRYPTO_THREAD_LOCAL public_drbg;
58/*
59 * The <private> DRBG
60 *
61 * Used by default for generating private keys using RAND_priv_bytes()
62 *
63 * The <private> DRBG is thread-local, i.e., there is one instance per thread.
64 */
65static CRYPTO_THREAD_LOCAL private_drbg;
66
67
68
69/* NIST SP 800-90A DRBG recommends the use of a personalization string. */
70static const char ossl_pers_string[] = "OpenSSL NIST SP 800-90A DRBG";
71
72static CRYPTO_ONCE rand_drbg_init = CRYPTO_ONCE_STATIC_INIT;
73
74
75
76static int rand_drbg_type = RAND_DRBG_TYPE;
77static unsigned int rand_drbg_flags = RAND_DRBG_FLAGS;
78
79static unsigned int master_reseed_interval = MASTER_RESEED_INTERVAL;
80static unsigned int slave_reseed_interval  = SLAVE_RESEED_INTERVAL;
81
82static time_t master_reseed_time_interval = MASTER_RESEED_TIME_INTERVAL;
83static time_t slave_reseed_time_interval  = SLAVE_RESEED_TIME_INTERVAL;
84
85/* A logical OR of all used DRBG flag bits (currently there is only one) */
86static const unsigned int rand_drbg_used_flags =
87    RAND_DRBG_FLAG_CTR_NO_DF;
88
89static RAND_DRBG *drbg_setup(RAND_DRBG *parent);
90
91static RAND_DRBG *rand_drbg_new(int secure,
92                                int type,
93                                unsigned int flags,
94                                RAND_DRBG *parent);
95
96/*
97 * Set/initialize |drbg| to be of type |type|, with optional |flags|.
98 *
99 * If |type| and |flags| are zero, use the defaults
100 *
101 * Returns 1 on success, 0 on failure.
102 */
103int RAND_DRBG_set(RAND_DRBG *drbg, int type, unsigned int flags)
104{
105    int ret = 1;
106
107    if (type == 0 && flags == 0) {
108        type = rand_drbg_type;
109        flags = rand_drbg_flags;
110    }
111
112    /* If set is called multiple times - clear the old one */
113    if (drbg->type != 0 && (type != drbg->type || flags != drbg->flags)) {
114        drbg->meth->uninstantiate(drbg);
115        rand_pool_free(drbg->adin_pool);
116        drbg->adin_pool = NULL;
117    }
118
119    drbg->state = DRBG_UNINITIALISED;
120    drbg->flags = flags;
121    drbg->type = type;
122
123    switch (type) {
124    default:
125        drbg->type = 0;
126        drbg->flags = 0;
127        drbg->meth = NULL;
128        RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_UNSUPPORTED_DRBG_TYPE);
129        return 0;
130    case 0:
131        /* Uninitialized; that's okay. */
132        drbg->meth = NULL;
133        return 1;
134    case NID_aes_128_ctr:
135    case NID_aes_192_ctr:
136    case NID_aes_256_ctr:
137        ret = drbg_ctr_init(drbg);
138        break;
139    }
140
141    if (ret == 0) {
142        drbg->state = DRBG_ERROR;
143        RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_ERROR_INITIALISING_DRBG);
144    }
145    return ret;
146}
147
148/*
149 * Set/initialize default |type| and |flag| for new drbg instances.
150 *
151 * Returns 1 on success, 0 on failure.
152 */
153int RAND_DRBG_set_defaults(int type, unsigned int flags)
154{
155    int ret = 1;
156
157    switch (type) {
158    default:
159        RANDerr(RAND_F_RAND_DRBG_SET_DEFAULTS, RAND_R_UNSUPPORTED_DRBG_TYPE);
160        return 0;
161    case NID_aes_128_ctr:
162    case NID_aes_192_ctr:
163    case NID_aes_256_ctr:
164        break;
165    }
166
167    if ((flags & ~rand_drbg_used_flags) != 0) {
168        RANDerr(RAND_F_RAND_DRBG_SET_DEFAULTS, RAND_R_UNSUPPORTED_DRBG_FLAGS);
169        return 0;
170    }
171
172    rand_drbg_type  = type;
173    rand_drbg_flags = flags;
174
175    return ret;
176}
177
178
179/*
180 * Allocate memory and initialize a new DRBG. The DRBG is allocated on
181 * the secure heap if |secure| is nonzero and the secure heap is enabled.
182 * The |parent|, if not NULL, will be used as random source for reseeding.
183 *
184 * Returns a pointer to the new DRBG instance on success, NULL on failure.
185 */
186static RAND_DRBG *rand_drbg_new(int secure,
187                                int type,
188                                unsigned int flags,
189                                RAND_DRBG *parent)
190{
191    RAND_DRBG *drbg = secure ? OPENSSL_secure_zalloc(sizeof(*drbg))
192                             : OPENSSL_zalloc(sizeof(*drbg));
193
194    if (drbg == NULL) {
195        RANDerr(RAND_F_RAND_DRBG_NEW, ERR_R_MALLOC_FAILURE);
196        return NULL;
197    }
198
199    drbg->secure = secure && CRYPTO_secure_allocated(drbg);
200    drbg->fork_id = openssl_get_fork_id();
201    drbg->parent = parent;
202
203    if (parent == NULL) {
204        drbg->get_entropy = rand_drbg_get_entropy;
205        drbg->cleanup_entropy = rand_drbg_cleanup_entropy;
206#ifndef RAND_DRBG_GET_RANDOM_NONCE
207        drbg->get_nonce = rand_drbg_get_nonce;
208        drbg->cleanup_nonce = rand_drbg_cleanup_nonce;
209#endif
210
211        drbg->reseed_interval = master_reseed_interval;
212        drbg->reseed_time_interval = master_reseed_time_interval;
213    } else {
214        drbg->get_entropy = rand_drbg_get_entropy;
215        drbg->cleanup_entropy = rand_drbg_cleanup_entropy;
216        /*
217         * Do not provide nonce callbacks, the child DRBGs will
218         * obtain their nonce using random bits from the parent.
219         */
220
221        drbg->reseed_interval = slave_reseed_interval;
222        drbg->reseed_time_interval = slave_reseed_time_interval;
223    }
224
225    if (RAND_DRBG_set(drbg, type, flags) == 0)
226        goto err;
227
228    if (parent != NULL) {
229        rand_drbg_lock(parent);
230        if (drbg->strength > parent->strength) {
231            /*
232             * We currently don't support the algorithm from NIST SP 800-90C
233             * 10.1.2 to use a weaker DRBG as source
234             */
235            rand_drbg_unlock(parent);
236            RANDerr(RAND_F_RAND_DRBG_NEW, RAND_R_PARENT_STRENGTH_TOO_WEAK);
237            goto err;
238        }
239        rand_drbg_unlock(parent);
240    }
241
242    return drbg;
243
244 err:
245    RAND_DRBG_free(drbg);
246
247    return NULL;
248}
249
250RAND_DRBG *RAND_DRBG_new(int type, unsigned int flags, RAND_DRBG *parent)
251{
252    return rand_drbg_new(0, type, flags, parent);
253}
254
255RAND_DRBG *RAND_DRBG_secure_new(int type, unsigned int flags, RAND_DRBG *parent)
256{
257    return rand_drbg_new(1, type, flags, parent);
258}
259
260/*
261 * Uninstantiate |drbg| and free all memory.
262 */
263void RAND_DRBG_free(RAND_DRBG *drbg)
264{
265    if (drbg == NULL)
266        return;
267
268    if (drbg->meth != NULL)
269        drbg->meth->uninstantiate(drbg);
270    rand_pool_free(drbg->adin_pool);
271    CRYPTO_THREAD_lock_free(drbg->lock);
272    CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DRBG, drbg, &drbg->ex_data);
273
274    if (drbg->secure)
275        OPENSSL_secure_clear_free(drbg, sizeof(*drbg));
276    else
277        OPENSSL_clear_free(drbg, sizeof(*drbg));
278}
279
280/*
281 * Instantiate |drbg|, after it has been initialized.  Use |pers| and
282 * |perslen| as prediction-resistance input.
283 *
284 * Requires that drbg->lock is already locked for write, if non-null.
285 *
286 * Returns 1 on success, 0 on failure.
287 */
288int RAND_DRBG_instantiate(RAND_DRBG *drbg,
289                          const unsigned char *pers, size_t perslen)
290{
291    unsigned char *nonce = NULL, *entropy = NULL;
292    size_t noncelen = 0, entropylen = 0;
293    size_t min_entropy = drbg->strength;
294    size_t min_entropylen = drbg->min_entropylen;
295    size_t max_entropylen = drbg->max_entropylen;
296
297    if (perslen > drbg->max_perslen) {
298        RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
299                RAND_R_PERSONALISATION_STRING_TOO_LONG);
300        goto end;
301    }
302
303    if (drbg->meth == NULL) {
304        RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
305                RAND_R_NO_DRBG_IMPLEMENTATION_SELECTED);
306        goto end;
307    }
308
309    if (drbg->state != DRBG_UNINITIALISED) {
310        RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
311                drbg->state == DRBG_ERROR ? RAND_R_IN_ERROR_STATE
312                                          : RAND_R_ALREADY_INSTANTIATED);
313        goto end;
314    }
315
316    drbg->state = DRBG_ERROR;
317
318    /*
319     * NIST SP800-90Ar1 section 9.1 says you can combine getting the entropy
320     * and nonce in 1 call by increasing the entropy with 50% and increasing
321     * the minimum length to accommodate the length of the nonce.
322     * We do this in case a nonce is require and get_nonce is NULL.
323     */
324    if (drbg->min_noncelen > 0 && drbg->get_nonce == NULL) {
325        min_entropy += drbg->strength / 2;
326        min_entropylen += drbg->min_noncelen;
327        max_entropylen += drbg->max_noncelen;
328    }
329
330    if (drbg->get_entropy != NULL)
331        entropylen = drbg->get_entropy(drbg, &entropy, min_entropy,
332                                       min_entropylen, max_entropylen, 0);
333    if (entropylen < min_entropylen
334            || entropylen > max_entropylen) {
335        RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_ENTROPY);
336        goto end;
337    }
338
339    if (drbg->min_noncelen > 0 && drbg->get_nonce != NULL) {
340        noncelen = drbg->get_nonce(drbg, &nonce, drbg->strength / 2,
341                                   drbg->min_noncelen, drbg->max_noncelen);
342        if (noncelen < drbg->min_noncelen || noncelen > drbg->max_noncelen) {
343            RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_NONCE);
344            goto end;
345        }
346    }
347
348    if (!drbg->meth->instantiate(drbg, entropy, entropylen,
349                         nonce, noncelen, pers, perslen)) {
350        RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_INSTANTIATING_DRBG);
351        goto end;
352    }
353
354    drbg->state = DRBG_READY;
355    drbg->generate_counter = 1;
356    drbg->reseed_time = time(NULL);
357    if (drbg->enable_reseed_propagation) {
358        if (drbg->parent == NULL)
359            tsan_counter(&drbg->reseed_counter);
360        else
361            tsan_store(&drbg->reseed_counter,
362                       tsan_load(&drbg->parent->reseed_counter));
363    }
364
365 end:
366    if (entropy != NULL && drbg->cleanup_entropy != NULL)
367        drbg->cleanup_entropy(drbg, entropy, entropylen);
368    if (nonce != NULL && drbg->cleanup_nonce != NULL)
369        drbg->cleanup_nonce(drbg, nonce, noncelen);
370    if (drbg->state == DRBG_READY)
371        return 1;
372    return 0;
373}
374
375/*
376 * Uninstantiate |drbg|. Must be instantiated before it can be used.
377 *
378 * Requires that drbg->lock is already locked for write, if non-null.
379 *
380 * Returns 1 on success, 0 on failure.
381 */
382int RAND_DRBG_uninstantiate(RAND_DRBG *drbg)
383{
384    if (drbg->meth == NULL) {
385        drbg->state = DRBG_ERROR;
386        RANDerr(RAND_F_RAND_DRBG_UNINSTANTIATE,
387                RAND_R_NO_DRBG_IMPLEMENTATION_SELECTED);
388        return 0;
389    }
390
391    /* Clear the entire drbg->ctr struct, then reset some important
392     * members of the drbg->ctr struct (e.g. keysize, df_ks) to their
393     * initial values.
394     */
395    drbg->meth->uninstantiate(drbg);
396    return RAND_DRBG_set(drbg, drbg->type, drbg->flags);
397}
398
399/*
400 * Reseed |drbg|, mixing in the specified data
401 *
402 * Requires that drbg->lock is already locked for write, if non-null.
403 *
404 * Returns 1 on success, 0 on failure.
405 */
406int RAND_DRBG_reseed(RAND_DRBG *drbg,
407                     const unsigned char *adin, size_t adinlen,
408                     int prediction_resistance)
409{
410    unsigned char *entropy = NULL;
411    size_t entropylen = 0;
412
413    if (drbg->state == DRBG_ERROR) {
414        RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_IN_ERROR_STATE);
415        return 0;
416    }
417    if (drbg->state == DRBG_UNINITIALISED) {
418        RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_NOT_INSTANTIATED);
419        return 0;
420    }
421
422    if (adin == NULL) {
423        adinlen = 0;
424    } else if (adinlen > drbg->max_adinlen) {
425        RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
426        return 0;
427    }
428
429    drbg->state = DRBG_ERROR;
430    if (drbg->get_entropy != NULL)
431        entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength,
432                                       drbg->min_entropylen,
433                                       drbg->max_entropylen,
434                                       prediction_resistance);
435    if (entropylen < drbg->min_entropylen
436            || entropylen > drbg->max_entropylen) {
437        RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ERROR_RETRIEVING_ENTROPY);
438        goto end;
439    }
440
441    if (!drbg->meth->reseed(drbg, entropy, entropylen, adin, adinlen))
442        goto end;
443
444    drbg->state = DRBG_READY;
445    drbg->generate_counter = 1;
446    drbg->reseed_time = time(NULL);
447    if (drbg->enable_reseed_propagation) {
448        if (drbg->parent == NULL)
449            tsan_counter(&drbg->reseed_counter);
450        else
451            tsan_store(&drbg->reseed_counter,
452                       tsan_load(&drbg->parent->reseed_counter));
453    }
454
455 end:
456    if (entropy != NULL && drbg->cleanup_entropy != NULL)
457        drbg->cleanup_entropy(drbg, entropy, entropylen);
458    if (drbg->state == DRBG_READY)
459        return 1;
460    return 0;
461}
462
463/*
464 * Restart |drbg|, using the specified entropy or additional input
465 *
466 * Tries its best to get the drbg instantiated by all means,
467 * regardless of its current state.
468 *
469 * Optionally, a |buffer| of |len| random bytes can be passed,
470 * which is assumed to contain at least |entropy| bits of entropy.
471 *
472 * If |entropy| > 0, the buffer content is used as entropy input.
473 *
474 * If |entropy| == 0, the buffer content is used as additional input
475 *
476 * Returns 1 on success, 0 on failure.
477 *
478 * This function is used internally only.
479 */
480int rand_drbg_restart(RAND_DRBG *drbg,
481                      const unsigned char *buffer, size_t len, size_t entropy)
482{
483    int reseeded = 0;
484    const unsigned char *adin = NULL;
485    size_t adinlen = 0;
486
487    if (drbg->seed_pool != NULL) {
488        RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR);
489        drbg->state = DRBG_ERROR;
490        rand_pool_free(drbg->seed_pool);
491        drbg->seed_pool = NULL;
492        return 0;
493    }
494
495    if (buffer != NULL) {
496        if (entropy > 0) {
497            if (drbg->max_entropylen < len) {
498                RANDerr(RAND_F_RAND_DRBG_RESTART,
499                    RAND_R_ENTROPY_INPUT_TOO_LONG);
500                drbg->state = DRBG_ERROR;
501                return 0;
502            }
503
504            if (entropy > 8 * len) {
505                RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_ENTROPY_OUT_OF_RANGE);
506                drbg->state = DRBG_ERROR;
507                return 0;
508            }
509
510            /* will be picked up by the rand_drbg_get_entropy() callback */
511            drbg->seed_pool = rand_pool_attach(buffer, len, entropy);
512            if (drbg->seed_pool == NULL)
513                return 0;
514        } else {
515            if (drbg->max_adinlen < len) {
516                RANDerr(RAND_F_RAND_DRBG_RESTART,
517                        RAND_R_ADDITIONAL_INPUT_TOO_LONG);
518                drbg->state = DRBG_ERROR;
519                return 0;
520            }
521            adin = buffer;
522            adinlen = len;
523        }
524    }
525
526    /* repair error state */
527    if (drbg->state == DRBG_ERROR)
528        RAND_DRBG_uninstantiate(drbg);
529
530    /* repair uninitialized state */
531    if (drbg->state == DRBG_UNINITIALISED) {
532        /* reinstantiate drbg */
533        RAND_DRBG_instantiate(drbg,
534                              (const unsigned char *) ossl_pers_string,
535                              sizeof(ossl_pers_string) - 1);
536        /* already reseeded. prevent second reseeding below */
537        reseeded = (drbg->state == DRBG_READY);
538    }
539
540    /* refresh current state if entropy or additional input has been provided */
541    if (drbg->state == DRBG_READY) {
542        if (adin != NULL) {
543            /*
544             * mix in additional input without reseeding
545             *
546             * Similar to RAND_DRBG_reseed(), but the provided additional
547             * data |adin| is mixed into the current state without pulling
548             * entropy from the trusted entropy source using get_entropy().
549             * This is not a reseeding in the strict sense of NIST SP 800-90A.
550             */
551            drbg->meth->reseed(drbg, adin, adinlen, NULL, 0);
552        } else if (reseeded == 0) {
553            /* do a full reseeding if it has not been done yet above */
554            if (!RAND_DRBG_reseed(drbg, NULL, 0, 0)) {
555                RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_RESEED_ERROR);
556            }
557        }
558    }
559
560    rand_pool_free(drbg->seed_pool);
561    drbg->seed_pool = NULL;
562
563    return drbg->state == DRBG_READY;
564}
565
566/*
567 * Generate |outlen| bytes into the buffer at |out|.  Reseed if we need
568 * to or if |prediction_resistance| is set.  Additional input can be
569 * sent in |adin| and |adinlen|.
570 *
571 * Requires that drbg->lock is already locked for write, if non-null.
572 *
573 * Returns 1 on success, 0 on failure.
574 *
575 */
576int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen,
577                       int prediction_resistance,
578                       const unsigned char *adin, size_t adinlen)
579{
580    int fork_id;
581    int reseed_required = 0;
582
583    if (drbg->state != DRBG_READY) {
584        /* try to recover from previous errors */
585        rand_drbg_restart(drbg, NULL, 0, 0);
586
587        if (drbg->state == DRBG_ERROR) {
588            RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_IN_ERROR_STATE);
589            return 0;
590        }
591        if (drbg->state == DRBG_UNINITIALISED) {
592            RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_NOT_INSTANTIATED);
593            return 0;
594        }
595    }
596
597    if (outlen > drbg->max_request) {
598        RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_REQUEST_TOO_LARGE_FOR_DRBG);
599        return 0;
600    }
601    if (adinlen > drbg->max_adinlen) {
602        RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
603        return 0;
604    }
605
606    fork_id = openssl_get_fork_id();
607
608    if (drbg->fork_id != fork_id) {
609        drbg->fork_id = fork_id;
610        reseed_required = 1;
611    }
612
613    if (drbg->reseed_interval > 0) {
614        if (drbg->generate_counter >= drbg->reseed_interval)
615            reseed_required = 1;
616    }
617    if (drbg->reseed_time_interval > 0) {
618        time_t now = time(NULL);
619        if (now < drbg->reseed_time
620            || now - drbg->reseed_time >= drbg->reseed_time_interval)
621            reseed_required = 1;
622    }
623    if (drbg->enable_reseed_propagation && drbg->parent != NULL) {
624        if (drbg->reseed_counter != tsan_load(&drbg->parent->reseed_counter))
625            reseed_required = 1;
626    }
627
628    if (reseed_required || prediction_resistance) {
629        if (!RAND_DRBG_reseed(drbg, adin, adinlen, prediction_resistance)) {
630            RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_RESEED_ERROR);
631            return 0;
632        }
633        adin = NULL;
634        adinlen = 0;
635    }
636
637    if (!drbg->meth->generate(drbg, out, outlen, adin, adinlen)) {
638        drbg->state = DRBG_ERROR;
639        RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_GENERATE_ERROR);
640        return 0;
641    }
642
643    drbg->generate_counter++;
644
645    return 1;
646}
647
648/*
649 * Generates |outlen| random bytes and stores them in |out|. It will
650 * using the given |drbg| to generate the bytes.
651 *
652 * Requires that drbg->lock is already locked for write, if non-null.
653 *
654 * Returns 1 on success 0 on failure.
655 */
656int RAND_DRBG_bytes(RAND_DRBG *drbg, unsigned char *out, size_t outlen)
657{
658    unsigned char *additional = NULL;
659    size_t additional_len;
660    size_t chunk;
661    size_t ret = 0;
662
663    if (drbg->adin_pool == NULL) {
664        if (drbg->type == 0)
665            goto err;
666        drbg->adin_pool = rand_pool_new(0, 0, 0, drbg->max_adinlen);
667        if (drbg->adin_pool == NULL)
668            goto err;
669    }
670
671    additional_len = rand_drbg_get_additional_data(drbg->adin_pool,
672                                                   &additional);
673
674    for ( ; outlen > 0; outlen -= chunk, out += chunk) {
675        chunk = outlen;
676        if (chunk > drbg->max_request)
677            chunk = drbg->max_request;
678        ret = RAND_DRBG_generate(drbg, out, chunk, 0, additional, additional_len);
679        if (!ret)
680            goto err;
681    }
682    ret = 1;
683
684 err:
685    if (additional != NULL)
686        rand_drbg_cleanup_additional_data(drbg->adin_pool, additional);
687
688    return ret;
689}
690
691/*
692 * Set the RAND_DRBG callbacks for obtaining entropy and nonce.
693 *
694 * Setting the callbacks is allowed only if the drbg has not been
695 * initialized yet. Otherwise, the operation will fail.
696 *
697 * Returns 1 on success, 0 on failure.
698 */
699int RAND_DRBG_set_callbacks(RAND_DRBG *drbg,
700                            RAND_DRBG_get_entropy_fn get_entropy,
701                            RAND_DRBG_cleanup_entropy_fn cleanup_entropy,
702                            RAND_DRBG_get_nonce_fn get_nonce,
703                            RAND_DRBG_cleanup_nonce_fn cleanup_nonce)
704{
705    if (drbg->state != DRBG_UNINITIALISED)
706        return 0;
707    drbg->get_entropy = get_entropy;
708    drbg->cleanup_entropy = cleanup_entropy;
709    drbg->get_nonce = get_nonce;
710    drbg->cleanup_nonce = cleanup_nonce;
711    return 1;
712}
713
714/*
715 * Set the reseed interval.
716 *
717 * The drbg will reseed automatically whenever the number of generate
718 * requests exceeds the given reseed interval. If the reseed interval
719 * is 0, then this feature is disabled.
720 *
721 * Returns 1 on success, 0 on failure.
722 */
723int RAND_DRBG_set_reseed_interval(RAND_DRBG *drbg, unsigned int interval)
724{
725    if (interval > MAX_RESEED_INTERVAL)
726        return 0;
727    drbg->reseed_interval = interval;
728    return 1;
729}
730
731/*
732 * Set the reseed time interval.
733 *
734 * The drbg will reseed automatically whenever the time elapsed since
735 * the last reseeding exceeds the given reseed time interval. For safety,
736 * a reseeding will also occur if the clock has been reset to a smaller
737 * value.
738 *
739 * Returns 1 on success, 0 on failure.
740 */
741int RAND_DRBG_set_reseed_time_interval(RAND_DRBG *drbg, time_t interval)
742{
743    if (interval > MAX_RESEED_TIME_INTERVAL)
744        return 0;
745    drbg->reseed_time_interval = interval;
746    return 1;
747}
748
749/*
750 * Set the default values for reseed (time) intervals of new DRBG instances
751 *
752 * The default values can be set independently for master DRBG instances
753 * (without a parent) and slave DRBG instances (with parent).
754 *
755 * Returns 1 on success, 0 on failure.
756 */
757
758int RAND_DRBG_set_reseed_defaults(
759                                  unsigned int _master_reseed_interval,
760                                  unsigned int _slave_reseed_interval,
761                                  time_t _master_reseed_time_interval,
762                                  time_t _slave_reseed_time_interval
763                                  )
764{
765    if (_master_reseed_interval > MAX_RESEED_INTERVAL
766        || _slave_reseed_interval > MAX_RESEED_INTERVAL)
767        return 0;
768
769    if (_master_reseed_time_interval > MAX_RESEED_TIME_INTERVAL
770        || _slave_reseed_time_interval > MAX_RESEED_TIME_INTERVAL)
771        return 0;
772
773    master_reseed_interval = _master_reseed_interval;
774    slave_reseed_interval = _slave_reseed_interval;
775
776    master_reseed_time_interval = _master_reseed_time_interval;
777    slave_reseed_time_interval = _slave_reseed_time_interval;
778
779    return 1;
780}
781
782/*
783 * Locks the given drbg. Locking a drbg which does not have locking
784 * enabled is considered a successful no-op.
785 *
786 * Returns 1 on success, 0 on failure.
787 */
788int rand_drbg_lock(RAND_DRBG *drbg)
789{
790    if (drbg->lock != NULL)
791        return CRYPTO_THREAD_write_lock(drbg->lock);
792
793    return 1;
794}
795
796/*
797 * Unlocks the given drbg. Unlocking a drbg which does not have locking
798 * enabled is considered a successful no-op.
799 *
800 * Returns 1 on success, 0 on failure.
801 */
802int rand_drbg_unlock(RAND_DRBG *drbg)
803{
804    if (drbg->lock != NULL)
805        return CRYPTO_THREAD_unlock(drbg->lock);
806
807    return 1;
808}
809
810/*
811 * Enables locking for the given drbg
812 *
813 * Locking can only be enabled if the random generator
814 * is in the uninitialized state.
815 *
816 * Returns 1 on success, 0 on failure.
817 */
818int rand_drbg_enable_locking(RAND_DRBG *drbg)
819{
820    if (drbg->state != DRBG_UNINITIALISED) {
821        RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
822                RAND_R_DRBG_ALREADY_INITIALIZED);
823        return 0;
824    }
825
826    if (drbg->lock == NULL) {
827        if (drbg->parent != NULL && drbg->parent->lock == NULL) {
828            RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
829                    RAND_R_PARENT_LOCKING_NOT_ENABLED);
830            return 0;
831        }
832
833        drbg->lock = CRYPTO_THREAD_lock_new();
834        if (drbg->lock == NULL) {
835            RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
836                    RAND_R_FAILED_TO_CREATE_LOCK);
837            return 0;
838        }
839    }
840
841    return 1;
842}
843
844/*
845 * Get and set the EXDATA
846 */
847int RAND_DRBG_set_ex_data(RAND_DRBG *drbg, int idx, void *arg)
848{
849    return CRYPTO_set_ex_data(&drbg->ex_data, idx, arg);
850}
851
852void *RAND_DRBG_get_ex_data(const RAND_DRBG *drbg, int idx)
853{
854    return CRYPTO_get_ex_data(&drbg->ex_data, idx);
855}
856
857
858/*
859 * The following functions provide a RAND_METHOD that works on the
860 * global DRBG.  They lock.
861 */
862
863/*
864 * Allocates a new global DRBG on the secure heap (if enabled) and
865 * initializes it with default settings.
866 *
867 * Returns a pointer to the new DRBG instance on success, NULL on failure.
868 */
869static RAND_DRBG *drbg_setup(RAND_DRBG *parent)
870{
871    RAND_DRBG *drbg;
872
873    drbg = RAND_DRBG_secure_new(rand_drbg_type, rand_drbg_flags, parent);
874    if (drbg == NULL)
875        return NULL;
876
877    /* Only the master DRBG needs to have a lock */
878    if (parent == NULL && rand_drbg_enable_locking(drbg) == 0)
879        goto err;
880
881    /* enable reseed propagation */
882    drbg->enable_reseed_propagation = 1;
883    drbg->reseed_counter = 1;
884
885    /*
886     * Ignore instantiation error to support just-in-time instantiation.
887     *
888     * The state of the drbg will be checked in RAND_DRBG_generate() and
889     * an automatic recovery is attempted.
890     */
891    (void)RAND_DRBG_instantiate(drbg,
892                                (const unsigned char *) ossl_pers_string,
893                                sizeof(ossl_pers_string) - 1);
894    return drbg;
895
896err:
897    RAND_DRBG_free(drbg);
898    return NULL;
899}
900
901/*
902 * Initialize the global DRBGs on first use.
903 * Returns 1 on success, 0 on failure.
904 */
905DEFINE_RUN_ONCE_STATIC(do_rand_drbg_init)
906{
907    /*
908     * ensure that libcrypto is initialized, otherwise the
909     * DRBG locks are not cleaned up properly
910     */
911    if (!OPENSSL_init_crypto(0, NULL))
912        return 0;
913
914    if (!CRYPTO_THREAD_init_local(&private_drbg, NULL))
915        return 0;
916
917    if (!CRYPTO_THREAD_init_local(&public_drbg, NULL))
918        goto err1;
919
920    master_drbg = drbg_setup(NULL);
921    if (master_drbg == NULL)
922        goto err2;
923
924    return 1;
925
926err2:
927    CRYPTO_THREAD_cleanup_local(&public_drbg);
928err1:
929    CRYPTO_THREAD_cleanup_local(&private_drbg);
930    return 0;
931}
932
933/* Clean up the global DRBGs before exit */
934void rand_drbg_cleanup_int(void)
935{
936    if (master_drbg != NULL) {
937        RAND_DRBG_free(master_drbg);
938        master_drbg = NULL;
939
940        CRYPTO_THREAD_cleanup_local(&private_drbg);
941        CRYPTO_THREAD_cleanup_local(&public_drbg);
942    }
943}
944
945void drbg_delete_thread_state(void)
946{
947    RAND_DRBG *drbg;
948
949    drbg = CRYPTO_THREAD_get_local(&public_drbg);
950    CRYPTO_THREAD_set_local(&public_drbg, NULL);
951    RAND_DRBG_free(drbg);
952
953    drbg = CRYPTO_THREAD_get_local(&private_drbg);
954    CRYPTO_THREAD_set_local(&private_drbg, NULL);
955    RAND_DRBG_free(drbg);
956}
957
958/* Implements the default OpenSSL RAND_bytes() method */
959static int drbg_bytes(unsigned char *out, int count)
960{
961    int ret;
962    RAND_DRBG *drbg = RAND_DRBG_get0_public();
963
964    if (drbg == NULL)
965        return 0;
966
967    ret = RAND_DRBG_bytes(drbg, out, count);
968
969    return ret;
970}
971
972/*
973 * Calculates the minimum length of a full entropy buffer
974 * which is necessary to seed (i.e. instantiate) the DRBG
975 * successfully.
976 */
977size_t rand_drbg_seedlen(RAND_DRBG *drbg)
978{
979    /*
980     * If no os entropy source is available then RAND_seed(buffer, bufsize)
981     * is expected to succeed if and only if the buffer length satisfies
982     * the following requirements, which follow from the calculations
983     * in RAND_DRBG_instantiate().
984     */
985    size_t min_entropy = drbg->strength;
986    size_t min_entropylen = drbg->min_entropylen;
987
988    /*
989     * Extra entropy for the random nonce in the absence of a
990     * get_nonce callback, see comment in RAND_DRBG_instantiate().
991     */
992    if (drbg->min_noncelen > 0 && drbg->get_nonce == NULL) {
993        min_entropy += drbg->strength / 2;
994        min_entropylen += drbg->min_noncelen;
995    }
996
997    /*
998     * Convert entropy requirement from bits to bytes
999     * (dividing by 8 without rounding upwards, because
1000     * all entropy requirements are divisible by 8).
1001     */
1002    min_entropy >>= 3;
1003
1004    /* Return a value that satisfies both requirements */
1005    return min_entropy > min_entropylen ? min_entropy : min_entropylen;
1006}
1007
1008/* Implements the default OpenSSL RAND_add() method */
1009static int drbg_add(const void *buf, int num, double randomness)
1010{
1011    int ret = 0;
1012    RAND_DRBG *drbg = RAND_DRBG_get0_master();
1013    size_t buflen;
1014    size_t seedlen;
1015
1016    if (drbg == NULL)
1017        return 0;
1018
1019    if (num < 0 || randomness < 0.0)
1020        return 0;
1021
1022    rand_drbg_lock(drbg);
1023    seedlen = rand_drbg_seedlen(drbg);
1024
1025    buflen = (size_t)num;
1026
1027    if (buflen < seedlen || randomness < (double) seedlen) {
1028#if defined(OPENSSL_RAND_SEED_NONE)
1029        /*
1030         * If no os entropy source is available, a reseeding will fail
1031         * inevitably. So we use a trick to mix the buffer contents into
1032         * the DRBG state without forcing a reseeding: we generate a
1033         * dummy random byte, using the buffer content as additional data.
1034         * Note: This won't work with RAND_DRBG_FLAG_CTR_NO_DF.
1035         */
1036        unsigned char dummy[1];
1037
1038        ret = RAND_DRBG_generate(drbg, dummy, sizeof(dummy), 0, buf, buflen);
1039        rand_drbg_unlock(drbg);
1040        return ret;
1041#else
1042        /*
1043         * If an os entropy source is available then we declare the buffer content
1044         * as additional data by setting randomness to zero and trigger a regular
1045         * reseeding.
1046         */
1047        randomness = 0.0;
1048#endif
1049    }
1050
1051
1052    if (randomness > (double)seedlen) {
1053        /*
1054         * The purpose of this check is to bound |randomness| by a
1055         * relatively small value in order to prevent an integer
1056         * overflow when multiplying by 8 in the rand_drbg_restart()
1057         * call below. Note that randomness is measured in bytes,
1058         * not bits, so this value corresponds to eight times the
1059         * security strength.
1060         */
1061        randomness = (double)seedlen;
1062    }
1063
1064    ret = rand_drbg_restart(drbg, buf, buflen, (size_t)(8 * randomness));
1065    rand_drbg_unlock(drbg);
1066
1067    return ret;
1068}
1069
1070/* Implements the default OpenSSL RAND_seed() method */
1071static int drbg_seed(const void *buf, int num)
1072{
1073    return drbg_add(buf, num, num);
1074}
1075
1076/* Implements the default OpenSSL RAND_status() method */
1077static int drbg_status(void)
1078{
1079    int ret;
1080    RAND_DRBG *drbg = RAND_DRBG_get0_master();
1081
1082    if (drbg == NULL)
1083        return 0;
1084
1085    rand_drbg_lock(drbg);
1086    ret = drbg->state == DRBG_READY ? 1 : 0;
1087    rand_drbg_unlock(drbg);
1088    return ret;
1089}
1090
1091/*
1092 * Get the master DRBG.
1093 * Returns pointer to the DRBG on success, NULL on failure.
1094 *
1095 */
1096RAND_DRBG *RAND_DRBG_get0_master(void)
1097{
1098    if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
1099        return NULL;
1100
1101    return master_drbg;
1102}
1103
1104/*
1105 * Get the public DRBG.
1106 * Returns pointer to the DRBG on success, NULL on failure.
1107 */
1108RAND_DRBG *RAND_DRBG_get0_public(void)
1109{
1110    RAND_DRBG *drbg;
1111
1112    if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
1113        return NULL;
1114
1115    drbg = CRYPTO_THREAD_get_local(&public_drbg);
1116    if (drbg == NULL) {
1117        if (!ossl_init_thread_start(OPENSSL_INIT_THREAD_RAND))
1118            return NULL;
1119        drbg = drbg_setup(master_drbg);
1120        CRYPTO_THREAD_set_local(&public_drbg, drbg);
1121    }
1122    return drbg;
1123}
1124
1125/*
1126 * Get the private DRBG.
1127 * Returns pointer to the DRBG on success, NULL on failure.
1128 */
1129RAND_DRBG *RAND_DRBG_get0_private(void)
1130{
1131    RAND_DRBG *drbg;
1132
1133    if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
1134        return NULL;
1135
1136    drbg = CRYPTO_THREAD_get_local(&private_drbg);
1137    if (drbg == NULL) {
1138        if (!ossl_init_thread_start(OPENSSL_INIT_THREAD_RAND))
1139            return NULL;
1140        drbg = drbg_setup(master_drbg);
1141        CRYPTO_THREAD_set_local(&private_drbg, drbg);
1142    }
1143    return drbg;
1144}
1145
1146RAND_METHOD rand_meth = {
1147    drbg_seed,
1148    drbg_bytes,
1149    NULL,
1150    drbg_add,
1151    drbg_bytes,
1152    drbg_status
1153};
1154
1155RAND_METHOD *RAND_OpenSSL(void)
1156{
1157    return &rand_meth;
1158}
1159