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
 270     if (perslen > drbg->max_perslen) {
 271         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
 272                 RAND_R_PERSONALISATION_STRING_TOO_LONG);
 273         goto end;
 274     }
 275
 276     if (drbg->meth == NULL)
 277     {
 278         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
 279                 RAND_R_NO_DRBG_IMPLEMENTATION_SELECTED);
 280         goto end;
 281     }
 282
 283     if (drbg->state != DRBG_UNINITIALISED) {
 284         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
 285                 drbg->state == DRBG_ERROR ? RAND_R_IN_ERROR_STATE
 286                                           : RAND_R_ALREADY_INSTANTIATED);
 287         goto end;
 288     }
 289
 290     drbg->state = DRBG_ERROR;
 291     if (drbg->get_entropy != NULL)
 292         entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength,
 293                                        drbg->min_entropylen,
 294                                        drbg->max_entropylen, 0);
 295     if (entropylen < drbg->min_entropylen
 296         || entropylen > drbg->max_entropylen) {
 297         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_ENTROPY);
 298         goto end;
 299     }
 300
 301     if (drbg->max_noncelen > 0 && drbg->get_nonce != NULL) {
 302         noncelen = drbg->get_nonce(drbg, &nonce, drbg->strength / 2,
 303                                    drbg->min_noncelen, drbg->max_noncelen);
 304         if (noncelen < drbg->min_noncelen || noncelen > drbg->max_noncelen) {
 305             RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
 306                     RAND_R_ERROR_RETRIEVING_NONCE);
 307             goto end;
 308         }
 309     }
 310
 311     if (!drbg->meth->instantiate(drbg, entropy, entropylen,
 312                          nonce, noncelen, pers, perslen)) {
 313         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_INSTANTIATING_DRBG);
 314         goto end;
 315     }
 316
 317     drbg->state = DRBG_READY;
 318     drbg->generate_counter = 0;
 319     drbg->reseed_time = time(NULL);
 320     if (drbg->reseed_counter > 0) {
 321         if (drbg->parent == NULL)
 322             drbg->reseed_counter++;
 323         else
 324             drbg->reseed_counter = drbg->parent->reseed_counter;
 325     }
 326
 327 end:
 328     if (entropy != NULL && drbg->cleanup_entropy != NULL)
 329         drbg->cleanup_entropy(drbg, entropy, entropylen);
 330     if (nonce != NULL && drbg->cleanup_nonce!= NULL )
 331         drbg->cleanup_nonce(drbg, nonce, noncelen);
 332     if (drbg->pool != NULL) {
 333         if (drbg->state == DRBG_READY) {
 334             RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
 335                     RAND_R_ERROR_ENTROPY_POOL_WAS_IGNORED);
 336             drbg->state = DRBG_ERROR;
 337         }
 338         rand_pool_free(drbg->pool);
 339         drbg->pool = NULL;
 340     }
 341     if (drbg->state == DRBG_READY)
 342         return 1;
 343     return 0;
 344 }
 345
 346 /*
 347  * Uninstantiate |drbg|. Must be instantiated before it can be used.
 348  *
 349  * Requires that drbg->lock is already locked for write, if non-null.
 350  *
 351  * Returns 1 on success, 0 on failure.
 352  */
 353 int RAND_DRBG_uninstantiate(RAND_DRBG *drbg)
 354 {
 355     if (drbg->meth == NULL)
 356     {
 357         RANDerr(RAND_F_RAND_DRBG_UNINSTANTIATE,
 358                 RAND_R_NO_DRBG_IMPLEMENTATION_SELECTED);
 359         return 0;
 360     }
 361
 362     /* Clear the entire drbg->ctr struct, then reset some important
 363      * members of the drbg->ctr struct (e.g. keysize, df_ks) to their
 364      * initial values.
 365      */
 366     drbg->meth->uninstantiate(drbg);
 367     return RAND_DRBG_set(drbg, drbg->type, drbg->flags);
 368 }
 369
 370 /*
 371  * Reseed |drbg|, mixing in the specified data
 372  *
 373  * Requires that drbg->lock is already locked for write, if non-null.
 374  *
 375  * Returns 1 on success, 0 on failure.
 376  */
 377 int RAND_DRBG_reseed(RAND_DRBG *drbg,
 378                      const unsigned char *adin, size_t adinlen,
 379                      int prediction_resistance)
 380 {
 381     unsigned char *entropy = NULL;
 382     size_t entropylen = 0;
 383
 384     if (drbg->state == DRBG_ERROR) {
 385         RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_IN_ERROR_STATE);
 386         return 0;
 387     }
 388     if (drbg->state == DRBG_UNINITIALISED) {
 389         RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_NOT_INSTANTIATED);
 390         return 0;
 391     }
 392
 393     if (adin == NULL)
 394         adinlen = 0;
 395     else if (adinlen > drbg->max_adinlen) {
 396         RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
 397         return 0;
 398     }
 399
 400     drbg->state = DRBG_ERROR;
 401     if (drbg->get_entropy != NULL)
 402         entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength,
 403                                        drbg->min_entropylen,
 404                                        drbg->max_entropylen,
 405                                        prediction_resistance);
 406     if (entropylen < drbg->min_entropylen
 407         || entropylen > drbg->max_entropylen) {
 408         RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ERROR_RETRIEVING_ENTROPY);
 409         goto end;
 410     }
 411
 412     if (!drbg->meth->reseed(drbg, entropy, entropylen, adin, adinlen))
 413         goto end;
 414
 415     drbg->state = DRBG_READY;
 416     drbg->generate_counter = 0;
 417     drbg->reseed_time = time(NULL);
 418     if (drbg->reseed_counter > 0) {
 419         if (drbg->parent == NULL)
 420             drbg->reseed_counter++;
 421         else
 422             drbg->reseed_counter = drbg->parent->reseed_counter;
 423     }
 424
 425 end:
 426     if (entropy != NULL && drbg->cleanup_entropy != NULL)
 427         drbg->cleanup_entropy(drbg, entropy, entropylen);
 428     if (drbg->state == DRBG_READY)
 429         return 1;
 430     return 0;
 431 }
 432
 433 /*
 434  * Restart |drbg|, using the specified entropy or additional input
 435  *
 436  * Tries its best to get the drbg instantiated by all means,
 437  * regardless of its current state.
 438  *
 439  * Optionally, a |buffer| of |len| random bytes can be passed,
 440  * which is assumed to contain at least |entropy| bits of entropy.
 441  *
 442  * If |entropy| > 0, the buffer content is used as entropy input.
 443  *
 444  * If |entropy| == 0, the buffer content is used as additional input
 445  *
 446  * Returns 1 on success, 0 on failure.
 447  *
 448  * This function is used internally only.
 449  */
 450 int rand_drbg_restart(RAND_DRBG *drbg,
 451                       const unsigned char *buffer, size_t len, size_t entropy)
 452 {
 453     int reseeded = 0;
 454     const unsigned char *adin = NULL;
 455     size_t adinlen = 0;
 456
 457     if (drbg->pool != NULL) {
 458         RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR);
 459         rand_pool_free(drbg->pool);
 460         drbg->pool = NULL;
 461     }
 462
 463     if (buffer != NULL) {
 464         if (entropy > 0) {
 465             if (drbg->max_entropylen < len) {
 466                 RANDerr(RAND_F_RAND_DRBG_RESTART,
 467                     RAND_R_ENTROPY_INPUT_TOO_LONG);
 468                 return 0;
 469             }
 470
 471             if (entropy > 8 * len) {
 472                 RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_ENTROPY_OUT_OF_RANGE);
 473                 return 0;
 474             }
 475
 476             /* will be picked up by the rand_drbg_get_entropy() callback */
 477             drbg->pool = rand_pool_new(entropy, len, len);
 478             if (drbg->pool == NULL)
 479                 return 0;
 480
 481             rand_pool_add(drbg->pool, buffer, len, entropy);
 482         } else {
 483             if (drbg->max_adinlen < len) {
 484                 RANDerr(RAND_F_RAND_DRBG_RESTART,
 485                         RAND_R_ADDITIONAL_INPUT_TOO_LONG);
 486                 return 0;
 487             }
 488             adin = buffer;
 489             adinlen = len;
 490         }
 491     }
 492
 493     /* repair error state */
 494     if (drbg->state == DRBG_ERROR)
 495         RAND_DRBG_uninstantiate(drbg);
 496
 497     /* repair uninitialized state */
 498     if (drbg->state == DRBG_UNINITIALISED) {
 499         /* reinstantiate drbg */
 500         RAND_DRBG_instantiate(drbg,
 501                               (const unsigned char *) ossl_pers_string,
 502                               sizeof(ossl_pers_string) - 1);
 503         /* already reseeded. prevent second reseeding below */
 504         reseeded = (drbg->state == DRBG_READY);
 505     }
 506
 507     /* refresh current state if entropy or additional input has been provided */
 508     if (drbg->state == DRBG_READY) {
 509         if (adin != NULL) {
 510             /*
 511              * mix in additional input without reseeding
 512              *
 513              * Similar to RAND_DRBG_reseed(), but the provided additional
 514              * data |adin| is mixed into the current state without pulling
 515              * entropy from the trusted entropy source using get_entropy().
 516              * This is not a reseeding in the strict sense of NIST SP 800-90A.
 517              */
 518             drbg->meth->reseed(drbg, adin, adinlen, NULL, 0);
 519         } else if (reseeded == 0) {
 520             /* do a full reseeding if it has not been done yet above */
 521             RAND_DRBG_reseed(drbg, NULL, 0, 0);
 522         }
 523     }
 524
 525     /* check whether a given entropy pool was cleared properly during reseed */
 526     if (drbg->pool != NULL) {
 527         drbg->state = DRBG_ERROR;
 528         RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR);
 529         rand_pool_free(drbg->pool);
 530         drbg->pool = NULL;
 531         return 0;
 532     }
 533
 534     return drbg->state == DRBG_READY;
 535 }
 536
 537 /*
 538  * Generate |outlen| bytes into the buffer at |out|.  Reseed if we need
 539  * to or if |prediction_resistance| is set.  Additional input can be
 540  * sent in |adin| and |adinlen|.
 541  *
 542  * Requires that drbg->lock is already locked for write, if non-null.
 543  *
 544  * Returns 1 on success, 0 on failure.
 545  *
 546  */
 547 int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen,
 548                        int prediction_resistance,
 549                        const unsigned char *adin, size_t adinlen)
 550 {
 551     int reseed_required = 0;
 552
 553     if (drbg->state != DRBG_READY) {
 554         /* try to recover from previous errors */
 555         rand_drbg_restart(drbg, NULL, 0, 0);
 556
 557         if (drbg->state == DRBG_ERROR) {
 558             RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_IN_ERROR_STATE);
 559             return 0;
 560         }
 561         if (drbg->state == DRBG_UNINITIALISED) {
 562             RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_NOT_INSTANTIATED);
 563             return 0;
 564         }
 565     }
 566
 567     if (outlen > drbg->max_request) {
 568         RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_REQUEST_TOO_LARGE_FOR_DRBG);
 569         return 0;
 570     }
 571     if (adinlen > drbg->max_adinlen) {
 572         RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
 573         return 0;
 574     }
 575
 576     if (drbg->fork_count != rand_fork_count) {
 577         drbg->fork_count = rand_fork_count;
 578         reseed_required = 1;
 579     }
 580
 581     if (drbg->reseed_interval > 0) {
 582         if (drbg->generate_counter >= drbg->reseed_interval)
 583             reseed_required = 1;
 584     }
 585     if (drbg->reseed_time_interval > 0) {
 586         time_t now = time(NULL);
 587         if (now < drbg->reseed_time
 588             || now - drbg->reseed_time >= drbg->reseed_time_interval)
 589             reseed_required = 1;
 590     }
 591     if (drbg->reseed_counter > 0 && drbg->parent != NULL) {
 592         if (drbg->reseed_counter != drbg->parent->reseed_counter)
 593             reseed_required = 1;
 594     }
 595
 596     if (reseed_required || prediction_resistance) {
 597         if (!RAND_DRBG_reseed(drbg, adin, adinlen, prediction_resistance)) {
 598             RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_RESEED_ERROR);
 599             return 0;
 600         }
 601         adin = NULL;
 602         adinlen = 0;
 603     }
 604
 605     if (!drbg->meth->generate(drbg, out, outlen, adin, adinlen)) {
 606         drbg->state = DRBG_ERROR;
 607         RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_GENERATE_ERROR);
 608         return 0;
 609     }
 610
 611     drbg->generate_counter++;
 612
 613     return 1;
 614 }
 615
 616 /*
 617  * Generates |outlen| random bytes and stores them in |out|. It will
 618  * using the given |drbg| to generate the bytes.
 619  *
 620  * Requires that drbg->lock is already locked for write, if non-null.
 621  *
 622  * Returns 1 on success 0 on failure.
 623  */
 624 int RAND_DRBG_bytes(RAND_DRBG *drbg, unsigned char *out, size_t outlen)
 625 {
 626     unsigned char *additional = NULL;
 627     size_t additional_len;
 628     size_t chunk;
 629     size_t ret;
 630
 631     additional_len = rand_drbg_get_additional_data(&additional, drbg->max_adinlen);
 632
 633     for ( ; outlen > 0; outlen -= chunk, out += chunk) {
 634         chunk = outlen;
 635         if (chunk > drbg->max_request)
 636             chunk = drbg->max_request;
 637         ret = RAND_DRBG_generate(drbg, out, chunk, 0, additional, additional_len);
 638         if (!ret)
 639             goto err;
 640     }
 641     ret = 1;
 642
 643 err:
 644     if (additional_len != 0)
 645         OPENSSL_secure_clear_free(additional, additional_len);
 646
 647     return ret;
 648 }
 649
 650 /*
 651  * Set the RAND_DRBG callbacks for obtaining entropy and nonce.
 652  *
 653  * Setting the callbacks is allowed only if the drbg has not been
 654  * initialized yet. Otherwise, the operation will fail.
 655  *
 656  * Returns 1 on success, 0 on failure.
 657  */
 658 int RAND_DRBG_set_callbacks(RAND_DRBG *drbg,
 659                             RAND_DRBG_get_entropy_fn get_entropy,
 660                             RAND_DRBG_cleanup_entropy_fn cleanup_entropy,
 661                             RAND_DRBG_get_nonce_fn get_nonce,
 662                             RAND_DRBG_cleanup_nonce_fn cleanup_nonce)
 663 {
 664     if (drbg->state != DRBG_UNINITIALISED)
 665         return 0;
 666     drbg->get_entropy = get_entropy;
 667     drbg->cleanup_entropy = cleanup_entropy;
 668     drbg->get_nonce = get_nonce;
 669     drbg->cleanup_nonce = cleanup_nonce;
 670     return 1;
 671 }
 672
 673 /*
 674  * Set the reseed interval.
 675  *
 676  * The drbg will reseed automatically whenever the number of generate
 677  * requests exceeds the given reseed interval. If the reseed interval
 678  * is 0, then this feature is disabled.
 679  *
 680  * Returns 1 on success, 0 on failure.
 681  */
 682 int RAND_DRBG_set_reseed_interval(RAND_DRBG *drbg, unsigned int interval)
 683 {
 684     if (interval > MAX_RESEED_INTERVAL)
 685         return 0;
 686     drbg->reseed_interval = interval;
 687     return 1;
 688 }
 689
 690 /*
 691  * Set the reseed time interval.
 692  *
 693  * The drbg will reseed automatically whenever the time elapsed since
 694  * the last reseeding exceeds the given reseed time interval. For safety,
 695  * a reseeding will also occur if the clock has been reset to a smaller
 696  * value.
 697  *
 698  * Returns 1 on success, 0 on failure.
 699  */
 700 int RAND_DRBG_set_reseed_time_interval(RAND_DRBG *drbg, time_t interval)
 701 {
 702     if (interval > MAX_RESEED_TIME_INTERVAL)
 703         return 0;
 704     drbg->reseed_time_interval = interval;
 705     return 1;
 706 }
 707
 708 /*
 709  * Set the default values for reseed (time) intervals of new DRBG instances
 710  *
 711  * The default values can be set independently for master DRBG instances
 712  * (without a parent) and slave DRBG instances (with parent).
 713  *
 714  * Returns 1 on success, 0 on failure.
 715  */
 716
 717 int RAND_DRBG_set_reseed_defaults(
 718                                   unsigned int _master_reseed_interval,
 719                                   unsigned int _slave_reseed_interval,
 720                                   time_t _master_reseed_time_interval,
 721                                   time_t _slave_reseed_time_interval
 722                                   )
 723 {
 724     if (_master_reseed_interval > MAX_RESEED_INTERVAL
 725         || _slave_reseed_interval > MAX_RESEED_INTERVAL)
 726         return 0;
 727
 728     if (_master_reseed_time_interval > MAX_RESEED_TIME_INTERVAL
 729         || _slave_reseed_time_interval > MAX_RESEED_TIME_INTERVAL)
 730         return 0;
 731
 732     master_reseed_interval = _master_reseed_interval;
 733     slave_reseed_interval = _slave_reseed_interval;
 734
 735     master_reseed_time_interval = _master_reseed_time_interval;
 736     slave_reseed_time_interval = _slave_reseed_time_interval;
 737
 738     return 1;
 739 }
 740
 741 /*
 742  * Locks the given drbg. Locking a drbg which does not have locking
 743  * enabled is considered a successful no-op.
 744  *
 745  * Returns 1 on success, 0 on failure.
 746  */
 747 int rand_drbg_lock(RAND_DRBG *drbg)
 748 {
 749     if (drbg->lock != NULL)
 750         return CRYPTO_THREAD_write_lock(drbg->lock);
 751
 752     return 1;
 753 }
 754
 755 /*
 756  * Unlocks the given drbg. Unlocking 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_unlock(RAND_DRBG *drbg)
 762 {
 763     if (drbg->lock != NULL)
 764         return CRYPTO_THREAD_unlock(drbg->lock);
 765
 766     return 1;
 767 }
 768
 769 /*
 770  * Enables locking for the given drbg
 771  *
 772  * Locking can only be enabled if the random generator
 773  * is in the uninitialized state.
 774  *
 775  * Returns 1 on success, 0 on failure.
 776  */
 777 int rand_drbg_enable_locking(RAND_DRBG *drbg)
 778 {
 779     if (drbg->state != DRBG_UNINITIALISED) {
 780         RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
 781                 RAND_R_DRBG_ALREADY_INITIALIZED);
 782         return 0;
 783     }
 784
 785     if (drbg->lock == NULL) {
 786         if (drbg->parent != NULL && drbg->parent->lock == NULL) {
 787             RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
 788                     RAND_R_PARENT_LOCKING_NOT_ENABLED);
 789             return 0;
 790         }
 791
 792         drbg->lock = CRYPTO_THREAD_lock_new();
 793         if (drbg->lock == NULL) {
 794             RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
 795                     RAND_R_FAILED_TO_CREATE_LOCK);
 796             return 0;
 797         }
 798     }
 799
 800     return 1;
 801 }
 802
 803 /*
 804  * Get and set the EXDATA
 805  */
 806 int RAND_DRBG_set_ex_data(RAND_DRBG *drbg, int idx, void *arg)
 807 {
 808     return CRYPTO_set_ex_data(&drbg->ex_data, idx, arg);
 809 }
 810
 811 void *RAND_DRBG_get_ex_data(const RAND_DRBG *drbg, int idx)
 812 {
 813     return CRYPTO_get_ex_data(&drbg->ex_data, idx);
 814 }
 815
 816
 817 /*
 818  * The following functions provide a RAND_METHOD that works on the
 819  * global DRBG.  They lock.
 820  */
 821
 822 /*
 823  * Allocates a new global DRBG on the secure heap (if enabled) and
 824  * initializes it with default settings.
 825  *
 826  * Returns a pointer to the new DRBG instance on success, NULL on failure.
 827  */
 828 static RAND_DRBG *drbg_setup(RAND_DRBG *parent)
 829 {
 830     RAND_DRBG *drbg;
 831
 832     drbg = RAND_DRBG_secure_new(rand_drbg_type, rand_drbg_flags, parent);
 833     if (drbg == NULL)
 834         return NULL;
 835
 836     /* Only the master DRBG needs to have a lock */
 837     if (parent == NULL && rand_drbg_enable_locking(drbg) == 0)
 838         goto err;
 839
 840     /* enable seed propagation */
 841     drbg->reseed_counter = 1;
 842
 843     /*
 844      * Ignore instantiation error so support just-in-time instantiation.
 845      *
 846      * The state of the drbg will be checked in RAND_DRBG_generate() and
 847      * an automatic recovery is attempted.
 848      */
 849     RAND_DRBG_instantiate(drbg,
 850                           (const unsigned char *) ossl_pers_string,
 851                           sizeof(ossl_pers_string) - 1);
 852     return drbg;
 853
 854 err:
 855     RAND_DRBG_free(drbg);
 856     return NULL;
 857 }
 858
 859 /*
 860  * Initialize the global DRBGs on first use.
 861  * Returns 1 on success, 0 on failure.
 862  */
 863 DEFINE_RUN_ONCE_STATIC(do_rand_drbg_init)
 864 {
 865     int ret = 1;
 866
 867     /*
 868      * ensure that libcrypto is initialized, otherwise the
 869      * DRBG locks are not cleaned up properly
 870      */
 871     if (!OPENSSL_init_crypto(0, NULL))
 872         return 0;
 873
 874     ossl_init_thread_start(OPENSSL_INIT_THREAD_RAND);
 875
 876     master_drbg = drbg_setup(NULL);
 877
 878     ret &= CRYPTO_THREAD_init_local(&private_drbg, NULL);
 879     ret &= CRYPTO_THREAD_init_local(&public_drbg, NULL);
 880
 881     if (master_drbg == NULL || ret == 0)
 882         return 0;
 883
 884     return 1;
 885 }
 886
 887 /* Clean up the global DRBGs before exit */
 888 void rand_drbg_cleanup_int(void)
 889 {
 890     RAND_DRBG_free(master_drbg);
 891     master_drbg = NULL;
 892
 893     CRYPTO_THREAD_cleanup_local(&private_drbg);
 894     CRYPTO_THREAD_cleanup_local(&public_drbg);
 895 }
 896
 897 void drbg_delete_thread_state()
 898 {
 899     RAND_DRBG *drbg;
 900
 901     drbg = CRYPTO_THREAD_get_local(&public_drbg);
 902     RAND_DRBG_free(drbg);
 903
 904     drbg = CRYPTO_THREAD_get_local(&private_drbg);
 905     RAND_DRBG_free(drbg);
 906 }
 907
 908 /* Implements the default OpenSSL RAND_bytes() method */
 909 static int drbg_bytes(unsigned char *out, int count)
 910 {
 911     int ret;
 912     RAND_DRBG *drbg = RAND_DRBG_get0_public();
 913
 914     if (drbg == NULL)
 915         return 0;
 916
 917     ret = RAND_DRBG_bytes(drbg, out, count);
 918
 919     return ret;
 920 }
 921
 922 /* Implements the default OpenSSL RAND_add() method */
 923 static int drbg_add(const void *buf, int num, double randomness)
 924 {
 925     int ret = 0;
 926     RAND_DRBG *drbg = RAND_DRBG_get0_master();
 927
 928     if (drbg == NULL)
 929         return 0;
 930
 931     if (num < 0 || randomness < 0.0)
 932         return 0;
 933
 934     if (randomness > (double)drbg->max_entropylen) {
 935         /*
 936          * The purpose of this check is to bound |randomness| by a
 937          * relatively small value in order to prevent an integer
 938          * overflow when multiplying by 8 in the rand_drbg_restart()
 939          * call below.
 940          */
 941         return 0;
 942     }
 943
 944     rand_drbg_lock(drbg);
 945     ret = rand_drbg_restart(drbg, buf,
 946                             (size_t)(unsigned int)num,
 947                             (size_t)(8*randomness));
 948     rand_drbg_unlock(drbg);
 949
 950     return ret;
 951 }
 952
 953 /* Implements the default OpenSSL RAND_seed() method */
 954 static int drbg_seed(const void *buf, int num)
 955 {
 956     return drbg_add(buf, num, num);
 957 }
 958
 959 /* Implements the default OpenSSL RAND_status() method */
 960 static int drbg_status(void)
 961 {
 962     int ret;
 963     RAND_DRBG *drbg = RAND_DRBG_get0_master();
 964
 965     if (drbg == NULL)
 966         return 0;
 967
 968     rand_drbg_lock(drbg);
 969     ret = drbg->state == DRBG_READY ? 1 : 0;
 970     rand_drbg_unlock(drbg);
 971     return ret;
 972 }
 973
 974 /*
 975  * Get the master DRBG.
 976  * Returns pointer to the DRBG on success, NULL on failure.
 977  *
 978  */
 979 RAND_DRBG *RAND_DRBG_get0_master(void)
 980 {
 981     if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
 982         return NULL;
 983
 984     return master_drbg;
 985 }
 986
 987 /*
 988  * Get the public DRBG.
 989  * Returns pointer to the DRBG on success, NULL on failure.
 990  */
 991 RAND_DRBG *RAND_DRBG_get0_public(void)
 992 {
 993     RAND_DRBG *drbg;
 994
 995     if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
 996         return NULL;
 997
 998     drbg = CRYPTO_THREAD_get_local(&public_drbg);
 999     if (drbg == NULL) {
1000         ossl_init_thread_start(OPENSSL_INIT_THREAD_RAND);
1001         drbg = drbg_setup(master_drbg);
1002         CRYPTO_THREAD_set_local(&public_drbg, drbg);
1003     }
1004     return drbg;
1005 }
1006
1007 /*
1008  * Get the private DRBG.
1009  * Returns pointer to the DRBG on success, NULL on failure.
1010  */
1011 RAND_DRBG *RAND_DRBG_get0_private(void)
1012 {
1013     RAND_DRBG *drbg;
1014
1015     if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
1016         return NULL;
1017
1018     drbg = CRYPTO_THREAD_get_local(&private_drbg);
1019     if (drbg == NULL) {
1020         ossl_init_thread_start(OPENSSL_INIT_THREAD_RAND);
1021         drbg = drbg_setup(master_drbg);
1022         CRYPTO_THREAD_set_local(&private_drbg, drbg);
1023     }
1024     return drbg;
1025 }
1026
1027 RAND_METHOD rand_meth = {
1028     drbg_seed,
1029     drbg_bytes,
1030     NULL,
1031     drbg_add,
1032     drbg_bytes,
1033     drbg_status
1034 };
1035
1036 RAND_METHOD *RAND_OpenSSL(void)
1037 {
1038     return &rand_meth;
1039 }