crypto/rand/drbg_lib.c

   1 /*
   2  * Copyright 2011-2018 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_lcl.h"
  15 #include "internal/thread_once.h"
  16 #include "internal/rand_int.h"
  17 #include "internal/cryptlib_int.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  */
  49 static 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  */
  57 static 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  */
  65 static CRYPTO_THREAD_LOCAL private_drbg;
  66
  67
  68
  69 /* NIST SP 800-90A DRBG recommends the use of a personalization string. */
  70 static const char ossl_pers_string[] = "OpenSSL NIST SP 800-90A DRBG";
  71
  72 static CRYPTO_ONCE rand_drbg_init = CRYPTO_ONCE_STATIC_INIT;
  73
  74
  75
  76 static int rand_drbg_type = RAND_DRBG_TYPE;
  77 static unsigned int rand_drbg_flags = RAND_DRBG_FLAGS;
  78
  79 static unsigned int master_reseed_interval = MASTER_RESEED_INTERVAL;
  80 static unsigned int slave_reseed_interval  = SLAVE_RESEED_INTERVAL;
  81
  82 static time_t master_reseed_time_interval = MASTER_RESEED_TIME_INTERVAL;
  83 static time_t slave_reseed_time_interval  = SLAVE_RESEED_TIME_INTERVAL;
  84
  85 static RAND_DRBG *drbg_setup(RAND_DRBG *parent);
  86
  87 static RAND_DRBG *rand_drbg_new(int secure,
  88                                 int type,
  89                                 unsigned int flags,
  90                                 RAND_DRBG *parent);
  91
  92 /*
  93  * Set/initialize |drbg| to be of type |type|, with optional |flags|.
  94  *
  95  * If |type| and |flags| are zero, use the defaults
  96  *
  97  * Returns 1 on success, 0 on failure.
  98  */
  99 int RAND_DRBG_set(RAND_DRBG *drbg, int type, unsigned int flags)
 100 {
 101     int ret = 1;
 102
 103     if (type == 0 && flags == 0) {
 104         type = rand_drbg_type;
 105         flags = rand_drbg_flags;
 106     }
 107
 108     drbg->state = DRBG_UNINITIALISED;
 109     drbg->flags = flags;
 110     drbg->type = type;
 111
 112     switch (type) {
 113     default:
 114         RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_UNSUPPORTED_DRBG_TYPE);
 115         return 0;
 116     case 0:
 117         /* Uninitialized; that's okay. */
 118         return 1;
 119     case NID_aes_128_ctr:
 120     case NID_aes_192_ctr:
 121     case NID_aes_256_ctr:
 122         ret = drbg_ctr_init(drbg);
 123         break;
 124     }
 125
 126     if (ret == 0)
 127         RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_ERROR_INITIALISING_DRBG);
 128     return ret;
 129 }
 130
 131 /*
 132  * Set/initialize default |type| and |flag| for new drbg instances.
 133  *
 134  * Returns 1 on success, 0 on failure.
 135  */
 136 int RAND_DRBG_set_defaults(int type, unsigned int flags)
 137 {
 138     int ret = 1;
 139
 140     switch (type) {
 141     default:
 142         RANDerr(RAND_F_RAND_DRBG_SET_DEFAULTS, RAND_R_UNSUPPORTED_DRBG_TYPE);
 143         return 0;
 144     case NID_aes_128_ctr:
 145     case NID_aes_192_ctr:
 146     case NID_aes_256_ctr:
 147         break;
 148     }
 149
 150     if ((flags & ~RAND_DRBG_USED_FLAGS) != 0) {
 151         RANDerr(RAND_F_RAND_DRBG_SET_DEFAULTS, RAND_R_UNSUPPORTED_DRBG_FLAGS);
 152         return 0;
 153     }
 154
 155     rand_drbg_type  = type;
 156     rand_drbg_flags = flags;
 157
 158     return ret;
 159 }
 160
 161
 162 /*
 163  * Allocate memory and initialize a new DRBG. The DRBG is allocated on
 164  * the secure heap if |secure| is nonzero and the secure heap is enabled.
 165  * The |parent|, if not NULL, will be used as random source for reseeding.
 166  *
 167  * Returns a pointer to the new DRBG instance on success, NULL on failure.
 168  */
 169 static RAND_DRBG *rand_drbg_new(int secure,
 170                                 int type,
 171                                 unsigned int flags,
 172                                 RAND_DRBG *parent)
 173 {
 174     RAND_DRBG *drbg = secure ?
 175         OPENSSL_secure_zalloc(sizeof(*drbg)) : OPENSSL_zalloc(sizeof(*drbg));
 176
 177     if (drbg == NULL) {
 178         RANDerr(RAND_F_RAND_DRBG_NEW, ERR_R_MALLOC_FAILURE);
 179         return NULL;
 180     }
 181
 182     drbg->secure = secure && CRYPTO_secure_allocated(drbg);
 183     drbg->fork_count = rand_fork_count;
 184     drbg->parent = parent;
 185
 186     if (parent == NULL) {
 187         drbg->reseed_interval = master_reseed_interval;
 188         drbg->reseed_time_interval = master_reseed_time_interval;
 189     } else {
 190         drbg->reseed_interval = slave_reseed_interval;
 191         drbg->reseed_time_interval = slave_reseed_time_interval;
 192     }
 193
 194     if (RAND_DRBG_set(drbg, type, flags) == 0)
 195         goto err;
 196
 197     if (parent != NULL) {
 198         rand_drbg_lock(parent);
 199         if (drbg->strength > parent->strength) {
 200             /*
 201              * We currently don't support the algorithm from NIST SP 800-90C
 202              * 10.1.2 to use a weaker DRBG as source
 203              */
 204             rand_drbg_unlock(parent);
 205             RANDerr(RAND_F_RAND_DRBG_NEW, RAND_R_PARENT_STRENGTH_TOO_WEAK);
 206             goto err;
 207         }
 208         rand_drbg_unlock(parent);
 209     }
 210
 211     if (!RAND_DRBG_set_callbacks(drbg, rand_drbg_get_entropy,
 212                                  rand_drbg_cleanup_entropy,
 213                                  NULL, NULL))
 214         goto err;
 215
 216     return drbg;
 217
 218 err:
 219     if (drbg->secure)
 220         OPENSSL_secure_free(drbg);
 221     else
 222         OPENSSL_free(drbg);
 223
 224     return NULL;
 225 }
 226
 227 RAND_DRBG *RAND_DRBG_new(int type, unsigned int flags, RAND_DRBG *parent)
 228 {
 229     return rand_drbg_new(0, type, flags, parent);
 230 }
 231
 232 RAND_DRBG *RAND_DRBG_secure_new(int type, unsigned int flags, RAND_DRBG *parent)
 233 {
 234     return rand_drbg_new(1, type, flags, parent);
 235 }
 236
 237 /*
 238  * Uninstantiate |drbg| and free all memory.
 239  */
 240 void RAND_DRBG_free(RAND_DRBG *drbg)
 241 {
 242     if (drbg == NULL)
 243         return;
 244
 245     if (drbg->meth != NULL)
 246         drbg->meth->uninstantiate(drbg);
 247     CRYPTO_THREAD_lock_free(drbg->lock);
 248     CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DRBG, drbg, &drbg->ex_data);
 249
 250     if (drbg->secure)
 251         OPENSSL_secure_clear_free(drbg, sizeof(*drbg));
 252     else
 253         OPENSSL_clear_free(drbg, sizeof(*drbg));
 254 }
 255
 256 /*
 257  * Instantiate |drbg|, after it has been initialized.  Use |pers| and
 258  * |perslen| as prediction-resistance input.
 259  *
 260  * Requires that drbg->lock is already locked for write, if non-null.
 261  *
 262  * Returns 1 on success, 0 on failure.
 263  */
 264 int RAND_DRBG_instantiate(RAND_DRBG *drbg,
 265                           const unsigned char *pers, size_t perslen)
 266 {
 267     unsigned char *nonce = NULL, *entropy = NULL;
 268     size_t noncelen = 0, entropylen = 0;
 269     size_t min_entropy = drbg->strength;
 270     size_t min_entropylen = drbg->min_entropylen;
 271     size_t max_entropylen = drbg->max_entropylen;
 272
 273     if (perslen > drbg->max_perslen) {
 274         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
 275                 RAND_R_PERSONALISATION_STRING_TOO_LONG);
 276         goto end;
 277     }
 278
 279     if (drbg->meth == NULL)
 280     {
 281         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
 282                 RAND_R_NO_DRBG_IMPLEMENTATION_SELECTED);
 283         goto end;
 284     }
 285
 286     if (drbg->state != DRBG_UNINITIALISED) {
 287         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
 288                 drbg->state == DRBG_ERROR ? RAND_R_IN_ERROR_STATE
 289                                           : RAND_R_ALREADY_INSTANTIATED);
 290         goto end;
 291     }
 292
 293     drbg->state = DRBG_ERROR;
 294
 295     /*
 296      * NIST SP800-90Ar1 section 9.1 says you can combine getting the entropy
 297      * and nonce in 1 call by increasing the entropy with 50% and increasing
 298      * the minimum length to accomadate the length of the nonce.
 299      * We do this in case a nonce is require and get_nonce is NULL.
 300      */
 301     if (drbg->min_noncelen > 0 && drbg->get_nonce == NULL) {
 302         min_entropy += drbg->strength / 2;
 303         min_entropylen += drbg->min_noncelen;
 304         max_entropylen += drbg->max_noncelen;
 305     }
 306
 307     if (drbg->get_entropy != NULL)
 308         entropylen = drbg->get_entropy(drbg, &entropy, min_entropy,
 309                                        min_entropylen, max_entropylen, 0);
 310     if (entropylen < min_entropylen
 311         || entropylen > max_entropylen) {
 312         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_ENTROPY);
 313         goto end;
 314     }
 315
 316     if (drbg->min_noncelen > 0 && drbg->get_nonce != NULL) {
 317         noncelen = drbg->get_nonce(drbg, &nonce, drbg->strength / 2,
 318                                    drbg->min_noncelen, drbg->max_noncelen);
 319         if (noncelen < drbg->min_noncelen || noncelen > drbg->max_noncelen) {
 320             RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_NONCE);
 321             goto end;
 322         }
 323     }
 324
 325     if (!drbg->meth->instantiate(drbg, entropy, entropylen,
 326                          nonce, noncelen, pers, perslen)) {
 327         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_INSTANTIATING_DRBG);
 328         goto end;
 329     }
 330
 331     drbg->state = DRBG_READY;
 332     drbg->generate_counter = 0;
 333     drbg->reseed_time = time(NULL);
 334     if (drbg->reseed_counter > 0) {
 335         if (drbg->parent == NULL)
 336             drbg->reseed_counter++;
 337         else
 338             drbg->reseed_counter = drbg->parent->reseed_counter;
 339     }
 340
 341 end:
 342     if (entropy != NULL && drbg->cleanup_entropy != NULL)
 343         drbg->cleanup_entropy(drbg, entropy, entropylen);
 344     if (nonce != NULL && drbg->cleanup_nonce!= NULL )
 345         drbg->cleanup_nonce(drbg, nonce, noncelen);
 346     if (drbg->pool != NULL) {
 347         if (drbg->state == DRBG_READY) {
 348             RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
 349                     RAND_R_ERROR_ENTROPY_POOL_WAS_IGNORED);
 350             drbg->state = DRBG_ERROR;
 351         }
 352         rand_pool_free(drbg->pool);
 353         drbg->pool = NULL;
 354     }
 355     if (drbg->state == DRBG_READY)
 356         return 1;
 357     return 0;
 358 }
 359
 360 /*
 361  * Uninstantiate |drbg|. Must be instantiated before it can be used.
 362  *
 363  * Requires that drbg->lock is already locked for write, if non-null.
 364  *
 365  * Returns 1 on success, 0 on failure.
 366  */
 367 int RAND_DRBG_uninstantiate(RAND_DRBG *drbg)
 368 {
 369     if (drbg->meth == NULL)
 370     {
 371         RANDerr(RAND_F_RAND_DRBG_UNINSTANTIATE,
 372                 RAND_R_NO_DRBG_IMPLEMENTATION_SELECTED);
 373         return 0;
 374     }
 375
 376     /* Clear the entire drbg->ctr struct, then reset some important
 377      * members of the drbg->ctr struct (e.g. keysize, df_ks) to their
 378      * initial values.
 379      */
 380     drbg->meth->uninstantiate(drbg);
 381     return RAND_DRBG_set(drbg, drbg->type, drbg->flags);
 382 }
 383
 384 /*
 385  * Reseed |drbg|, mixing in the specified data
 386  *
 387  * Requires that drbg->lock is already locked for write, if non-null.
 388  *
 389  * Returns 1 on success, 0 on failure.
 390  */
 391 int RAND_DRBG_reseed(RAND_DRBG *drbg,
 392                      const unsigned char *adin, size_t adinlen,
 393                      int prediction_resistance)
 394 {
 395     unsigned char *entropy = NULL;
 396     size_t entropylen = 0;
 397
 398     if (drbg->state == DRBG_ERROR) {
 399         RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_IN_ERROR_STATE);
 400         return 0;
 401     }
 402     if (drbg->state == DRBG_UNINITIALISED) {
 403         RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_NOT_INSTANTIATED);
 404         return 0;
 405     }
 406
 407     if (adin == NULL)
 408         adinlen = 0;
 409     else if (adinlen > drbg->max_adinlen) {
 410         RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
 411         return 0;
 412     }
 413
 414     drbg->state = DRBG_ERROR;
 415     if (drbg->get_entropy != NULL)
 416         entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength,
 417                                        drbg->min_entropylen,
 418                                        drbg->max_entropylen,
 419                                        prediction_resistance);
 420     if (entropylen < drbg->min_entropylen
 421         || entropylen > drbg->max_entropylen) {
 422         RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ERROR_RETRIEVING_ENTROPY);
 423         goto end;
 424     }
 425
 426     if (!drbg->meth->reseed(drbg, entropy, entropylen, adin, adinlen))
 427         goto end;
 428
 429     drbg->state = DRBG_READY;
 430     drbg->generate_counter = 0;
 431     drbg->reseed_time = time(NULL);
 432     if (drbg->reseed_counter > 0) {
 433         if (drbg->parent == NULL)
 434             drbg->reseed_counter++;
 435         else
 436             drbg->reseed_counter = drbg->parent->reseed_counter;
 437     }
 438
 439 end:
 440     if (entropy != NULL && drbg->cleanup_entropy != NULL)
 441         drbg->cleanup_entropy(drbg, entropy, entropylen);
 442     if (drbg->state == DRBG_READY)
 443         return 1;
 444     return 0;
 445 }
 446
 447 /*
 448  * Restart |drbg|, using the specified entropy or additional input
 449  *
 450  * Tries its best to get the drbg instantiated by all means,
 451  * regardless of its current state.
 452  *
 453  * Optionally, a |buffer| of |len| random bytes can be passed,
 454  * which is assumed to contain at least |entropy| bits of entropy.
 455  *
 456  * If |entropy| > 0, the buffer content is used as entropy input.
 457  *
 458  * If |entropy| == 0, the buffer content is used as additional input
 459  *
 460  * Returns 1 on success, 0 on failure.
 461  *
 462  * This function is used internally only.
 463  */
 464 int rand_drbg_restart(RAND_DRBG *drbg,
 465                       const unsigned char *buffer, size_t len, size_t entropy)
 466 {
 467     int reseeded = 0;
 468     const unsigned char *adin = NULL;
 469     size_t adinlen = 0;
 470
 471     if (drbg->pool != NULL) {
 472         RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR);
 473         rand_pool_free(drbg->pool);
 474         drbg->pool = NULL;
 475     }
 476
 477     if (buffer != NULL) {
 478         if (entropy > 0) {
 479             if (drbg->max_entropylen < len) {
 480                 RANDerr(RAND_F_RAND_DRBG_RESTART,
 481                     RAND_R_ENTROPY_INPUT_TOO_LONG);
 482                 return 0;
 483             }
 484
 485             if (entropy > 8 * len) {
 486                 RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_ENTROPY_OUT_OF_RANGE);
 487                 return 0;
 488             }
 489
 490             /* will be picked up by the rand_drbg_get_entropy() callback */
 491             drbg->pool = rand_pool_new(entropy, len, len);
 492             if (drbg->pool == NULL)
 493                 return 0;
 494
 495             rand_pool_add(drbg->pool, buffer, len, entropy);
 496         } else {
 497             if (drbg->max_adinlen < len) {
 498                 RANDerr(RAND_F_RAND_DRBG_RESTART,
 499                         RAND_R_ADDITIONAL_INPUT_TOO_LONG);
 500                 return 0;
 501             }
 502             adin = buffer;
 503             adinlen = len;
 504         }
 505     }
 506
 507     /* repair error state */
 508     if (drbg->state == DRBG_ERROR)
 509         RAND_DRBG_uninstantiate(drbg);
 510
 511     /* repair uninitialized state */
 512     if (drbg->state == DRBG_UNINITIALISED) {
 513         /* reinstantiate drbg */
 514         RAND_DRBG_instantiate(drbg,
 515                               (const unsigned char *) ossl_pers_string,
 516                               sizeof(ossl_pers_string) - 1);
 517         /* already reseeded. prevent second reseeding below */
 518         reseeded = (drbg->state == DRBG_READY);
 519     }
 520
 521     /* refresh current state if entropy or additional input has been provided */
 522     if (drbg->state == DRBG_READY) {
 523         if (adin != NULL) {
 524             /*
 525              * mix in additional input without reseeding
 526              *
 527              * Similar to RAND_DRBG_reseed(), but the provided additional
 528              * data |adin| is mixed into the current state without pulling
 529              * entropy from the trusted entropy source using get_entropy().
 530              * This is not a reseeding in the strict sense of NIST SP 800-90A.
 531              */
 532             drbg->meth->reseed(drbg, adin, adinlen, NULL, 0);
 533         } else if (reseeded == 0) {
 534             /* do a full reseeding if it has not been done yet above */
 535             RAND_DRBG_reseed(drbg, NULL, 0, 0);
 536         }
 537     }
 538
 539     /* check whether a given entropy pool was cleared properly during reseed */
 540     if (drbg->pool != NULL) {
 541         drbg->state = DRBG_ERROR;
 542         RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR);
 543         rand_pool_free(drbg->pool);
 544         drbg->pool = NULL;
 545         return 0;
 546     }
 547
 548     return drbg->state == DRBG_READY;
 549 }
 550
 551 /*
 552  * Generate |outlen| bytes into the buffer at |out|.  Reseed if we need
 553  * to or if |prediction_resistance| is set.  Additional input can be
 554  * sent in |adin| and |adinlen|.
 555  *
 556  * Requires that drbg->lock is already locked for write, if non-null.
 557  *
 558  * Returns 1 on success, 0 on failure.
 559  *
 560  */
 561 int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen,
 562                        int prediction_resistance,
 563                        const unsigned char *adin, size_t adinlen)
 564 {
 565     int reseed_required = 0;
 566
 567     if (drbg->state != DRBG_READY) {
 568         /* try to recover from previous errors */
 569         rand_drbg_restart(drbg, NULL, 0, 0);
 570
 571         if (drbg->state == DRBG_ERROR) {
 572             RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_IN_ERROR_STATE);
 573             return 0;
 574         }
 575         if (drbg->state == DRBG_UNINITIALISED) {
 576             RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_NOT_INSTANTIATED);
 577             return 0;
 578         }
 579     }
 580
 581     if (outlen > drbg->max_request) {
 582         RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_REQUEST_TOO_LARGE_FOR_DRBG);
 583         return 0;
 584     }
 585     if (adinlen > drbg->max_adinlen) {
 586         RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
 587         return 0;
 588     }
 589
 590     if (drbg->fork_count != rand_fork_count) {
 591         drbg->fork_count = rand_fork_count;
 592         reseed_required = 1;
 593     }
 594
 595     if (drbg->reseed_interval > 0) {
 596         if (drbg->generate_counter >= drbg->reseed_interval)
 597             reseed_required = 1;
 598     }
 599     if (drbg->reseed_time_interval > 0) {
 600         time_t now = time(NULL);
 601         if (now < drbg->reseed_time
 602             || now - drbg->reseed_time >= drbg->reseed_time_interval)
 603             reseed_required = 1;
 604     }
 605     if (drbg->reseed_counter > 0 && drbg->parent != NULL) {
 606         if (drbg->reseed_counter != drbg->parent->reseed_counter)
 607             reseed_required = 1;
 608     }
 609
 610     if (reseed_required || prediction_resistance) {
 611         if (!RAND_DRBG_reseed(drbg, adin, adinlen, prediction_resistance)) {
 612             RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_RESEED_ERROR);
 613             return 0;
 614         }
 615         adin = NULL;
 616         adinlen = 0;
 617     }
 618
 619     if (!drbg->meth->generate(drbg, out, outlen, adin, adinlen)) {
 620         drbg->state = DRBG_ERROR;
 621         RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_GENERATE_ERROR);
 622         return 0;
 623     }
 624
 625     drbg->generate_counter++;
 626
 627     return 1;
 628 }
 629
 630 /*
 631  * Generates |outlen| random bytes and stores them in |out|. It will
 632  * using the given |drbg| to generate the bytes.
 633  *
 634  * Requires that drbg->lock is already locked for write, if non-null.
 635  *
 636  * Returns 1 on success 0 on failure.
 637  */
 638 int RAND_DRBG_bytes(RAND_DRBG *drbg, unsigned char *out, size_t outlen)
 639 {
 640     unsigned char *additional = NULL;
 641     size_t additional_len;
 642     size_t chunk;
 643     size_t ret;
 644
 645     additional_len = rand_drbg_get_additional_data(&additional, drbg->max_adinlen);
 646
 647     for ( ; outlen > 0; outlen -= chunk, out += chunk) {
 648         chunk = outlen;
 649         if (chunk > drbg->max_request)
 650             chunk = drbg->max_request;
 651         ret = RAND_DRBG_generate(drbg, out, chunk, 0, additional, additional_len);
 652         if (!ret)
 653             goto err;
 654     }
 655     ret = 1;
 656
 657 err:
 658     if (additional_len != 0)
 659         OPENSSL_secure_clear_free(additional, additional_len);
 660
 661     return ret;
 662 }
 663
 664 /*
 665  * Set the RAND_DRBG callbacks for obtaining entropy and nonce.
 666  *
 667  * Setting the callbacks is allowed only if the drbg has not been
 668  * initialized yet. Otherwise, the operation will fail.
 669  *
 670  * Returns 1 on success, 0 on failure.
 671  */
 672 int RAND_DRBG_set_callbacks(RAND_DRBG *drbg,
 673                             RAND_DRBG_get_entropy_fn get_entropy,
 674                             RAND_DRBG_cleanup_entropy_fn cleanup_entropy,
 675                             RAND_DRBG_get_nonce_fn get_nonce,
 676                             RAND_DRBG_cleanup_nonce_fn cleanup_nonce)
 677 {
 678     if (drbg->state != DRBG_UNINITIALISED)
 679         return 0;
 680     drbg->get_entropy = get_entropy;
 681     drbg->cleanup_entropy = cleanup_entropy;
 682     drbg->get_nonce = get_nonce;
 683     drbg->cleanup_nonce = cleanup_nonce;
 684     return 1;
 685 }
 686
 687 /*
 688  * Set the reseed interval.
 689  *
 690  * The drbg will reseed automatically whenever the number of generate
 691  * requests exceeds the given reseed interval. If the reseed interval
 692  * is 0, then this feature is disabled.
 693  *
 694  * Returns 1 on success, 0 on failure.
 695  */
 696 int RAND_DRBG_set_reseed_interval(RAND_DRBG *drbg, unsigned int interval)
 697 {
 698     if (interval > MAX_RESEED_INTERVAL)
 699         return 0;
 700     drbg->reseed_interval = interval;
 701     return 1;
 702 }
 703
 704 /*
 705  * Set the reseed time interval.
 706  *
 707  * The drbg will reseed automatically whenever the time elapsed since
 708  * the last reseeding exceeds the given reseed time interval. For safety,
 709  * a reseeding will also occur if the clock has been reset to a smaller
 710  * value.
 711  *
 712  * Returns 1 on success, 0 on failure.
 713  */
 714 int RAND_DRBG_set_reseed_time_interval(RAND_DRBG *drbg, time_t interval)
 715 {
 716     if (interval > MAX_RESEED_TIME_INTERVAL)
 717         return 0;
 718     drbg->reseed_time_interval = interval;
 719     return 1;
 720 }
 721
 722 /*
 723  * Set the default values for reseed (time) intervals of new DRBG instances
 724  *
 725  * The default values can be set independently for master DRBG instances
 726  * (without a parent) and slave DRBG instances (with parent).
 727  *
 728  * Returns 1 on success, 0 on failure.
 729  */
 730
 731 int RAND_DRBG_set_reseed_defaults(
 732                                   unsigned int _master_reseed_interval,
 733                                   unsigned int _slave_reseed_interval,
 734                                   time_t _master_reseed_time_interval,
 735                                   time_t _slave_reseed_time_interval
 736                                   )
 737 {
 738     if (_master_reseed_interval > MAX_RESEED_INTERVAL
 739         || _slave_reseed_interval > MAX_RESEED_INTERVAL)
 740         return 0;
 741
 742     if (_master_reseed_time_interval > MAX_RESEED_TIME_INTERVAL
 743         || _slave_reseed_time_interval > MAX_RESEED_TIME_INTERVAL)
 744         return 0;
 745
 746     master_reseed_interval = _master_reseed_interval;
 747     slave_reseed_interval = _slave_reseed_interval;
 748
 749     master_reseed_time_interval = _master_reseed_time_interval;
 750     slave_reseed_time_interval = _slave_reseed_time_interval;
 751
 752     return 1;
 753 }
 754
 755 /*
 756  * Locks the given drbg. Locking a drbg which does not have locking
 757  * enabled is considered a successful no-op.
 758  *
 759  * Returns 1 on success, 0 on failure.
 760  */
 761 int rand_drbg_lock(RAND_DRBG *drbg)
 762 {
 763     if (drbg->lock != NULL)
 764         return CRYPTO_THREAD_write_lock(drbg->lock);
 765
 766     return 1;
 767 }
 768
 769 /*
 770  * Unlocks the given drbg. Unlocking a drbg which does not have locking
 771  * enabled is considered a successful no-op.
 772  *
 773  * Returns 1 on success, 0 on failure.
 774  */
 775 int rand_drbg_unlock(RAND_DRBG *drbg)
 776 {
 777     if (drbg->lock != NULL)
 778         return CRYPTO_THREAD_unlock(drbg->lock);
 779
 780     return 1;
 781 }
 782
 783 /*
 784  * Enables locking for the given drbg
 785  *
 786  * Locking can only be enabled if the random generator
 787  * is in the uninitialized state.
 788  *
 789  * Returns 1 on success, 0 on failure.
 790  */
 791 int rand_drbg_enable_locking(RAND_DRBG *drbg)
 792 {
 793     if (drbg->state != DRBG_UNINITIALISED) {
 794         RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
 795                 RAND_R_DRBG_ALREADY_INITIALIZED);
 796         return 0;
 797     }
 798
 799     if (drbg->lock == NULL) {
 800         if (drbg->parent != NULL && drbg->parent->lock == NULL) {
 801             RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
 802                     RAND_R_PARENT_LOCKING_NOT_ENABLED);
 803             return 0;
 804         }
 805
 806         drbg->lock = CRYPTO_THREAD_lock_new();
 807         if (drbg->lock == NULL) {
 808             RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
 809                     RAND_R_FAILED_TO_CREATE_LOCK);
 810             return 0;
 811         }
 812     }
 813
 814     return 1;
 815 }
 816
 817 /*
 818  * Get and set the EXDATA
 819  */
 820 int RAND_DRBG_set_ex_data(RAND_DRBG *drbg, int idx, void *arg)
 821 {
 822     return CRYPTO_set_ex_data(&drbg->ex_data, idx, arg);
 823 }
 824
 825 void *RAND_DRBG_get_ex_data(const RAND_DRBG *drbg, int idx)
 826 {
 827     return CRYPTO_get_ex_data(&drbg->ex_data, idx);
 828 }
 829
 830
 831 /*
 832  * The following functions provide a RAND_METHOD that works on the
 833  * global DRBG.  They lock.
 834  */
 835
 836 /*
 837  * Allocates a new global DRBG on the secure heap (if enabled) and
 838  * initializes it with default settings.
 839  *
 840  * Returns a pointer to the new DRBG instance on success, NULL on failure.
 841  */
 842 static RAND_DRBG *drbg_setup(RAND_DRBG *parent)
 843 {
 844     RAND_DRBG *drbg;
 845
 846     drbg = RAND_DRBG_secure_new(rand_drbg_type, rand_drbg_flags, parent);
 847     if (drbg == NULL)
 848         return NULL;
 849
 850     /* Only the master DRBG needs to have a lock */
 851     if (parent == NULL && rand_drbg_enable_locking(drbg) == 0)
 852         goto err;
 853
 854     /* enable seed propagation */
 855     drbg->reseed_counter = 1;
 856
 857     /*
 858      * Ignore instantiation error so support just-in-time instantiation.
 859      *
 860      * The state of the drbg will be checked in RAND_DRBG_generate() and
 861      * an automatic recovery is attempted.
 862      */
 863     RAND_DRBG_instantiate(drbg,
 864                           (const unsigned char *) ossl_pers_string,
 865                           sizeof(ossl_pers_string) - 1);
 866     return drbg;
 867
 868 err:
 869     RAND_DRBG_free(drbg);
 870     return NULL;
 871 }
 872
 873 /*
 874  * Initialize the global DRBGs on first use.
 875  * Returns 1 on success, 0 on failure.
 876  */
 877 DEFINE_RUN_ONCE_STATIC(do_rand_drbg_init)
 878 {
 879     int ret = 1;
 880
 881     /*
 882      * ensure that libcrypto is initialized, otherwise the
 883      * DRBG locks are not cleaned up properly
 884      */
 885     if (!OPENSSL_init_crypto(0, NULL))
 886         return 0;
 887
 888     ossl_init_thread_start(OPENSSL_INIT_THREAD_RAND);
 889
 890     master_drbg = drbg_setup(NULL);
 891
 892     ret &= CRYPTO_THREAD_init_local(&private_drbg, NULL);
 893     ret &= CRYPTO_THREAD_init_local(&public_drbg, NULL);
 894
 895     if (master_drbg == NULL || ret == 0)
 896         return 0;
 897
 898     return 1;
 899 }
 900
 901 /* Clean up the global DRBGs before exit */
 902 void rand_drbg_cleanup_int(void)
 903 {
 904     RAND_DRBG_free(master_drbg);
 905     master_drbg = NULL;
 906
 907     CRYPTO_THREAD_cleanup_local(&private_drbg);
 908     CRYPTO_THREAD_cleanup_local(&public_drbg);
 909 }
 910
 911 void drbg_delete_thread_state()
 912 {
 913     RAND_DRBG *drbg;
 914
 915     drbg = CRYPTO_THREAD_get_local(&public_drbg);
 916     RAND_DRBG_free(drbg);
 917
 918     drbg = CRYPTO_THREAD_get_local(&private_drbg);
 919     RAND_DRBG_free(drbg);
 920 }
 921
 922 /* Implements the default OpenSSL RAND_bytes() method */
 923 static int drbg_bytes(unsigned char *out, int count)
 924 {
 925     int ret;
 926     RAND_DRBG *drbg = RAND_DRBG_get0_public();
 927
 928     if (drbg == NULL)
 929         return 0;
 930
 931     ret = RAND_DRBG_bytes(drbg, out, count);
 932
 933     return ret;
 934 }
 935
 936 /* Implements the default OpenSSL RAND_add() method */
 937 static int drbg_add(const void *buf, int num, double randomness)
 938 {
 939     int ret = 0;
 940     RAND_DRBG *drbg = RAND_DRBG_get0_master();
 941
 942     if (drbg == NULL)
 943         return 0;
 944
 945     if (num < 0 || randomness < 0.0)
 946         return 0;
 947
 948     if (randomness > (double)drbg->max_entropylen) {
 949         /*
 950          * The purpose of this check is to bound |randomness| by a
 951          * relatively small value in order to prevent an integer
 952          * overflow when multiplying by 8 in the rand_drbg_restart()
 953          * call below.
 954          */
 955         return 0;
 956     }
 957
 958     rand_drbg_lock(drbg);
 959     ret = rand_drbg_restart(drbg, buf,
 960                             (size_t)(unsigned int)num,
 961                             (size_t)(8*randomness));
 962     rand_drbg_unlock(drbg);
 963
 964     return ret;
 965 }
 966
 967 /* Implements the default OpenSSL RAND_seed() method */
 968 static int drbg_seed(const void *buf, int num)
 969 {
 970     return drbg_add(buf, num, num);
 971 }
 972
 973 /* Implements the default OpenSSL RAND_status() method */
 974 static int drbg_status(void)
 975 {
 976     int ret;
 977     RAND_DRBG *drbg = RAND_DRBG_get0_master();
 978
 979     if (drbg == NULL)
 980         return 0;
 981
 982     rand_drbg_lock(drbg);
 983     ret = drbg->state == DRBG_READY ? 1 : 0;
 984     rand_drbg_unlock(drbg);
 985     return ret;
 986 }
 987
 988 /*
 989  * Get the master DRBG.
 990  * Returns pointer to the DRBG on success, NULL on failure.
 991  *
 992  */
 993 RAND_DRBG *RAND_DRBG_get0_master(void)
 994 {
 995     if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
 996         return NULL;
 997
 998     return master_drbg;
 999 }
1000
1001 /*
1002  * Get the public DRBG.
1003  * Returns pointer to the DRBG on success, NULL on failure.
1004  */
1005 RAND_DRBG *RAND_DRBG_get0_public(void)
1006 {
1007     RAND_DRBG *drbg;
1008
1009     if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
1010         return NULL;
1011
1012     drbg = CRYPTO_THREAD_get_local(&public_drbg);
1013     if (drbg == NULL) {
1014         ossl_init_thread_start(OPENSSL_INIT_THREAD_RAND);
1015         drbg = drbg_setup(master_drbg);
1016         CRYPTO_THREAD_set_local(&public_drbg, drbg);
1017     }
1018     return drbg;
1019 }
1020
1021 /*
1022  * Get the private DRBG.
1023  * Returns pointer to the DRBG on success, NULL on failure.
1024  */
1025 RAND_DRBG *RAND_DRBG_get0_private(void)
1026 {
1027     RAND_DRBG *drbg;
1028
1029     if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
1030         return NULL;
1031
1032     drbg = CRYPTO_THREAD_get_local(&private_drbg);
1033     if (drbg == NULL) {
1034         ossl_init_thread_start(OPENSSL_INIT_THREAD_RAND);
1035         drbg = drbg_setup(master_drbg);
1036         CRYPTO_THREAD_set_local(&private_drbg, drbg);
1037     }
1038     return drbg;
1039 }
1040
1041 RAND_METHOD rand_meth = {
1042     drbg_seed,
1043     drbg_bytes,
1044     NULL,
1045     drbg_add,
1046     drbg_bytes,
1047     drbg_status
1048 };
1049
1050 RAND_METHOD *RAND_OpenSSL(void)
1051 {
1052     return &rand_meth;
1053 }