providers/implementations/rands/drbg.c

   1 /*
   2  * Copyright 2011-2021 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <string.h>
  11 #include <openssl/crypto.h>
  12 #include <openssl/err.h>
  13 #include <openssl/rand.h>
  14 #include <openssl/evp.h>
  15 #include "crypto/rand.h"
  16 #include <openssl/proverr.h>
  17 #include "drbg_local.h"
  18 #include "internal/thread_once.h"
  19 #include "crypto/cryptlib.h"
  20 #include "prov/seeding.h"
  21 #include "crypto/rand_pool.h"
  22 #include "prov/provider_ctx.h"
  23 #include "prov/providercommon.h"
  24
  25 /*
  26  * Support framework for NIST SP 800-90A DRBG
  27  *
  28  * See manual page PROV_DRBG(7) for a general overview.
  29  *
  30  * The OpenSSL model is to have new and free functions, and that new
  31  * does all initialization.  That is not the NIST model, which has
  32  * instantiation and un-instantiate, and re-use within a new/free
  33  * lifecycle.  (No doubt this comes from the desire to support hardware
  34  * DRBG, where allocation of resources on something like an HSM is
  35  * a much bigger deal than just re-setting an allocated resource.)
  36  */
  37
  38 /* NIST SP 800-90A DRBG recommends the use of a personalization string. */
  39 static const char ossl_pers_string[] = DRBG_DEFAULT_PERS_STRING;
  40
  41 static const OSSL_DISPATCH *find_call(const OSSL_DISPATCH *dispatch,
  42                                       int function);
  43
  44 static int rand_drbg_restart(PROV_DRBG *drbg);
  45
  46 int ossl_drbg_lock(void *vctx)
  47 {
  48     PROV_DRBG *drbg = vctx;
  49
  50     if (drbg == NULL || drbg->lock == NULL)
  51         return 1;
  52     return CRYPTO_THREAD_write_lock(drbg->lock);
  53 }
  54
  55 void ossl_drbg_unlock(void *vctx)
  56 {
  57     PROV_DRBG *drbg = vctx;
  58
  59     if (drbg != NULL && drbg->lock != NULL)
  60         CRYPTO_THREAD_unlock(drbg->lock);
  61 }
  62
  63 static int ossl_drbg_lock_parent(PROV_DRBG *drbg)
  64 {
  65     void *parent = drbg->parent;
  66
  67     if (parent != NULL
  68             && drbg->parent_lock != NULL
  69             && !drbg->parent_lock(parent)) {
  70         ERR_raise(ERR_LIB_PROV, PROV_R_PARENT_LOCKING_NOT_ENABLED);
  71         return 0;
  72     }
  73     return 1;
  74 }
  75
  76 static void ossl_drbg_unlock_parent(PROV_DRBG *drbg)
  77 {
  78     void *parent = drbg->parent;
  79
  80     if (parent != NULL && drbg->parent_unlock != NULL)
  81         drbg->parent_unlock(parent);
  82 }
  83
  84 static int get_parent_strength(PROV_DRBG *drbg, unsigned int *str)
  85 {
  86     OSSL_PARAM params[2] = { OSSL_PARAM_END, OSSL_PARAM_END };
  87     void *parent = drbg->parent;
  88     int res;
  89
  90     if (drbg->parent_get_ctx_params == NULL) {
  91         ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_GET_PARENT_STRENGTH);
  92         return 0;
  93     }
  94
  95     *params = OSSL_PARAM_construct_uint(OSSL_RAND_PARAM_STRENGTH, str);
  96     if (!ossl_drbg_lock_parent(drbg)) {
  97         ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_LOCK_PARENT);
  98         return 0;
  99     }
 100     res = drbg->parent_get_ctx_params(parent, params);
 101     ossl_drbg_unlock_parent(drbg);
 102     if (!res) {
 103         ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_GET_PARENT_STRENGTH);
 104         return 0;
 105     }
 106     return 1;
 107 }
 108
 109 static unsigned int get_parent_reseed_count(PROV_DRBG *drbg)
 110 {
 111     OSSL_PARAM params[2] = { OSSL_PARAM_END, OSSL_PARAM_END };
 112     void *parent = drbg->parent;
 113     unsigned int r = 0;
 114
 115     *params = OSSL_PARAM_construct_uint(OSSL_DRBG_PARAM_RESEED_COUNTER, &r);
 116     if (!ossl_drbg_lock_parent(drbg)) {
 117         ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_LOCK_PARENT);
 118         goto err;
 119     }
 120     if (!drbg->parent_get_ctx_params(parent, params))
 121         r = 0;
 122     ossl_drbg_unlock_parent(drbg);
 123     return r;
 124
 125  err:
 126     r = tsan_load(&drbg->reseed_counter) - 2;
 127     if (r == 0)
 128         r = UINT_MAX;
 129     return r;
 130 }
 131
 132 /*
 133  * Implements the get_entropy() callback
 134  *
 135  * If the DRBG has a parent, then the required amount of entropy input
 136  * is fetched using the parent's ossl_prov_drbg_generate().
 137  *
 138  * Otherwise, the entropy is polled from the system entropy sources
 139  * using ossl_pool_acquire_entropy().
 140  *
 141  * If a random pool has been added to the DRBG using RAND_add(), then
 142  * its entropy will be used up first.
 143  */
 144 size_t ossl_drbg_get_seed(void *vdrbg, unsigned char **pout,
 145                           int entropy, size_t min_len,
 146                           size_t max_len, int prediction_resistance,
 147                           const unsigned char *adin, size_t adin_len)
 148 {
 149     PROV_DRBG *drbg = (PROV_DRBG *)vdrbg;
 150     size_t bytes_needed;
 151     unsigned char *buffer;
 152
 153     /* Figure out how many bytes we need */
 154     bytes_needed = entropy >= 0 ? (entropy + 7) / 8 : 0;
 155     if (bytes_needed < min_len)
 156         bytes_needed = min_len;
 157     if (bytes_needed > max_len)
 158         bytes_needed = max_len;
 159
 160     /* Allocate storage */
 161     buffer = OPENSSL_secure_malloc(bytes_needed);
 162     if (buffer == NULL) {
 163         ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
 164         return 0;
 165     }
 166
 167     /*
 168      * Get random data.  Include our DRBG address as
 169      * additional input, in order to provide a distinction between
 170      * different DRBG child instances.
 171      *
 172      * Note: using the sizeof() operator on a pointer triggers
 173      *       a warning in some static code analyzers, but it's
 174      *       intentional and correct here.
 175      */
 176     if (!ossl_prov_drbg_generate(drbg, buffer, bytes_needed,
 177                                  drbg->strength, prediction_resistance,
 178                                  (unsigned char *)&drbg, sizeof(drbg))) {
 179         OPENSSL_secure_clear_free(buffer, bytes_needed);
 180         ERR_raise(ERR_LIB_PROV, PROV_R_GENERATE_ERROR);
 181         return 0;
 182     }
 183     *pout = buffer;
 184     return bytes_needed;
 185 }
 186
 187 /* Implements the cleanup_entropy() callback */
 188 void ossl_drbg_clear_seed(ossl_unused void *vdrbg,
 189                           unsigned char *out, size_t outlen)
 190 {
 191     OPENSSL_secure_clear_free(out, outlen);
 192 }
 193
 194 static size_t get_entropy(PROV_DRBG *drbg, unsigned char **pout, int entropy,
 195                           size_t min_len, size_t max_len,
 196                           int prediction_resistance)
 197 {
 198     size_t bytes;
 199     unsigned int p_str;
 200
 201     if (drbg->parent == NULL)
 202 #ifdef FIPS_MODULE
 203         return ossl_crngt_get_entropy(drbg, pout, entropy, min_len, max_len,
 204                                       prediction_resistance);
 205 #else
 206         return ossl_prov_get_entropy(drbg->provctx, pout, entropy, min_len,
 207                                      max_len);
 208 #endif
 209
 210     if (drbg->parent_get_seed == NULL) {
 211         ERR_raise(ERR_LIB_PROV, PROV_R_PARENT_CANNOT_SUPPLY_ENTROPY_SEED);
 212         return 0;
 213     }
 214     if (!get_parent_strength(drbg, &p_str))
 215         return 0;
 216     if (drbg->strength > p_str) {
 217         /*
 218          * We currently don't support the algorithm from NIST SP 800-90C
 219          * 10.1.2 to use a weaker DRBG as source
 220          */
 221         ERR_raise(ERR_LIB_PROV, PROV_R_PARENT_STRENGTH_TOO_WEAK);
 222         return 0;
 223     }
 224
 225     /*
 226      * Our lock is already held, but we need to lock our parent before
 227      * generating bits from it.  Note: taking the lock will be a no-op
 228      * if locking is not required (while drbg->parent->lock == NULL).
 229      */
 230     if (!ossl_drbg_lock_parent(drbg))
 231         return 0;
 232     /*
 233      * Get random data from parent.  Include our DRBG address as
 234      * additional input, in order to provide a distinction between
 235      * different DRBG child instances.
 236      *
 237      * Note: using the sizeof() operator on a pointer triggers
 238      *       a warning in some static code analyzers, but it's
 239      *       intentional and correct here.
 240      */
 241     bytes = drbg->parent_get_seed(drbg->parent, pout, drbg->strength,
 242                                   min_len, max_len, prediction_resistance,
 243                                   (unsigned char *)&drbg, sizeof(drbg));
 244     ossl_drbg_unlock_parent(drbg);
 245     return bytes;
 246 }
 247
 248 static void cleanup_entropy(PROV_DRBG *drbg, unsigned char *out, size_t outlen)
 249 {
 250     if (drbg->parent == NULL) {
 251 #ifdef FIPS_MODULE
 252         ossl_crngt_cleanup_entropy(drbg, out, outlen);
 253 #else
 254         ossl_prov_cleanup_entropy(drbg->provctx, out, outlen);
 255 #endif
 256     } else if (drbg->parent_clear_seed != NULL) {
 257         if (!ossl_drbg_lock_parent(drbg))
 258             return;
 259         drbg->parent_clear_seed(drbg, out, outlen);
 260         ossl_drbg_unlock_parent(drbg);
 261     }
 262 }
 263
 264 #ifndef PROV_RAND_GET_RANDOM_NONCE
 265 typedef struct prov_drbg_nonce_global_st {
 266     CRYPTO_RWLOCK *rand_nonce_lock;
 267     int rand_nonce_count;
 268 } PROV_DRBG_NONCE_GLOBAL;
 269
 270 /*
 271  * drbg_ossl_ctx_new() calls drgb_setup() which calls rand_drbg_get_nonce()
 272  * which needs to get the rand_nonce_lock out of the OSSL_LIB_CTX...but since
 273  * drbg_ossl_ctx_new() hasn't finished running yet we need the rand_nonce_lock
 274  * to be in a different global data object. Otherwise we will go into an
 275  * infinite recursion loop.
 276  */
 277 static void *prov_drbg_nonce_ossl_ctx_new(OSSL_LIB_CTX *libctx)
 278 {
 279     PROV_DRBG_NONCE_GLOBAL *dngbl = OPENSSL_zalloc(sizeof(*dngbl));
 280
 281     if (dngbl == NULL)
 282         return NULL;
 283
 284     dngbl->rand_nonce_lock = CRYPTO_THREAD_lock_new();
 285     if (dngbl->rand_nonce_lock == NULL) {
 286         OPENSSL_free(dngbl);
 287         return NULL;
 288     }
 289
 290     return dngbl;
 291 }
 292
 293 static void prov_drbg_nonce_ossl_ctx_free(void *vdngbl)
 294 {
 295     PROV_DRBG_NONCE_GLOBAL *dngbl = vdngbl;
 296
 297     if (dngbl == NULL)
 298         return;
 299
 300     CRYPTO_THREAD_lock_free(dngbl->rand_nonce_lock);
 301
 302     OPENSSL_free(dngbl);
 303 }
 304
 305 static const OSSL_LIB_CTX_METHOD drbg_nonce_ossl_ctx_method = {
 306     prov_drbg_nonce_ossl_ctx_new,
 307     prov_drbg_nonce_ossl_ctx_free,
 308 };
 309
 310 /* Get a nonce from the operating system */
 311 static size_t prov_drbg_get_nonce(PROV_DRBG *drbg, unsigned char **pout,
 312                                   size_t min_len, size_t max_len)
 313 {
 314     size_t ret = 0, n;
 315     unsigned char *buf = NULL;
 316     OSSL_LIB_CTX *libctx = ossl_prov_ctx_get0_libctx(drbg->provctx);
 317     PROV_DRBG_NONCE_GLOBAL *dngbl
 318         = ossl_lib_ctx_get_data(libctx, OSSL_LIB_CTX_DRBG_NONCE_INDEX,
 319                                 &drbg_nonce_ossl_ctx_method);
 320     struct {
 321         void *drbg;
 322         int count;
 323     } data;
 324
 325     if (dngbl == NULL)
 326         return 0;
 327
 328     if (drbg->parent != NULL && drbg->parent_nonce != NULL) {
 329         n = drbg->parent_nonce(drbg->parent, NULL, 0, drbg->min_noncelen,
 330                                drbg->max_noncelen);
 331         if (n > 0 && (buf = OPENSSL_malloc(n)) != NULL) {
 332             ret = drbg->parent_nonce(drbg->parent, buf, 0,
 333                                      drbg->min_noncelen, drbg->max_noncelen);
 334             if (ret == n) {
 335                 *pout = buf;
 336                 return ret;
 337             }
 338             OPENSSL_free(buf);
 339         }
 340     }
 341
 342     /* Use the built in nonce source plus some of our specifics */
 343     memset(&data, 0, sizeof(data));
 344     data.drbg = drbg;
 345     CRYPTO_atomic_add(&dngbl->rand_nonce_count, 1, &data.count,
 346                       dngbl->rand_nonce_lock);
 347     return ossl_prov_get_nonce(drbg->provctx, pout, min_len, max_len,
 348                                &data, sizeof(data));
 349 }
 350 #endif /* PROV_RAND_GET_RANDOM_NONCE */
 351
 352 /*
 353  * Instantiate |drbg|, after it has been initialized.  Use |pers| and
 354  * |perslen| as prediction-resistance input.
 355  *
 356  * Requires that drbg->lock is already locked for write, if non-null.
 357  *
 358  * Returns 1 on success, 0 on failure.
 359  */
 360 int ossl_prov_drbg_instantiate(PROV_DRBG *drbg, unsigned int strength,
 361                                int prediction_resistance,
 362                                const unsigned char *pers, size_t perslen)
 363 {
 364     unsigned char *nonce = NULL, *entropy = NULL;
 365     size_t noncelen = 0, entropylen = 0;
 366     size_t min_entropy, min_entropylen, max_entropylen;
 367
 368     if (!ossl_prov_is_running())
 369         return 0;
 370
 371     if (strength > drbg->strength) {
 372         ERR_raise(ERR_LIB_PROV, PROV_R_INSUFFICIENT_DRBG_STRENGTH);
 373         goto end;
 374     }
 375     min_entropy = drbg->strength;
 376     min_entropylen = drbg->min_entropylen;
 377     max_entropylen = drbg->max_entropylen;
 378
 379     if (pers == NULL) {
 380         pers = (const unsigned char *)ossl_pers_string;
 381         perslen = sizeof(ossl_pers_string);
 382     }
 383     if (perslen > drbg->max_perslen) {
 384         ERR_raise(ERR_LIB_PROV, PROV_R_PERSONALISATION_STRING_TOO_LONG);
 385         goto end;
 386     }
 387
 388     if (drbg->state != EVP_RAND_STATE_UNINITIALISED) {
 389         if (drbg->state == EVP_RAND_STATE_ERROR)
 390             ERR_raise(ERR_LIB_PROV, PROV_R_IN_ERROR_STATE);
 391         else
 392             ERR_raise(ERR_LIB_PROV, PROV_R_ALREADY_INSTANTIATED);
 393         goto end;
 394     }
 395
 396     drbg->state = EVP_RAND_STATE_ERROR;
 397
 398     if (drbg->min_noncelen > 0) {
 399         if (drbg->parent_nonce != NULL) {
 400             noncelen = drbg->parent_nonce(drbg->parent, NULL, drbg->strength,
 401                                           drbg->min_noncelen,
 402                                           drbg->max_noncelen);
 403             if (noncelen == 0) {
 404                 ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_NONCE);
 405                 goto end;
 406             }
 407             nonce = OPENSSL_malloc(noncelen);
 408             if (nonce == NULL) {
 409                 ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_NONCE);
 410                 goto end;
 411             }
 412             if (noncelen != drbg->parent_nonce(drbg->parent, nonce,
 413                                                drbg->strength,
 414                                                drbg->min_noncelen,
 415                                                drbg->max_noncelen)) {
 416                 ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_NONCE);
 417                 goto end;
 418             }
 419 #ifndef PROV_RAND_GET_RANDOM_NONCE
 420         } else if (drbg->parent != NULL) {
 421 #endif
 422             /*
 423              * NIST SP800-90Ar1 section 9.1 says you can combine getting
 424              * the entropy and nonce in 1 call by increasing the entropy
 425              * with 50% and increasing the minimum length to accommodate
 426              * the length of the nonce. We do this in case a nonce is
 427              * required and there is no parental nonce capability.
 428              */
 429             min_entropy += drbg->strength / 2;
 430             min_entropylen += drbg->min_noncelen;
 431             max_entropylen += drbg->max_noncelen;
 432         }
 433 #ifndef PROV_RAND_GET_RANDOM_NONCE
 434         else { /* parent == NULL */
 435             noncelen = prov_drbg_get_nonce(drbg, &nonce, drbg->min_noncelen,
 436                                            drbg->max_noncelen);
 437             if (noncelen < drbg->min_noncelen
 438                     || noncelen > drbg->max_noncelen) {
 439                 ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_NONCE);
 440                 goto end;
 441             }
 442         }
 443 #endif
 444     }
 445
 446     drbg->reseed_next_counter = tsan_load(&drbg->reseed_counter);
 447     if (drbg->reseed_next_counter) {
 448         drbg->reseed_next_counter++;
 449         if (!drbg->reseed_next_counter)
 450             drbg->reseed_next_counter = 1;
 451     }
 452
 453     entropylen = get_entropy(drbg, &entropy, min_entropy,
 454                              min_entropylen, max_entropylen,
 455                              prediction_resistance);
 456     if (entropylen < min_entropylen
 457             || entropylen > max_entropylen) {
 458         ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_ENTROPY);
 459         goto end;
 460     }
 461
 462     if (!drbg->instantiate(drbg, entropy, entropylen, nonce, noncelen,
 463                            pers, perslen)) {
 464         ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_INSTANTIATING_DRBG);
 465         goto end;
 466     }
 467
 468     drbg->state = EVP_RAND_STATE_READY;
 469     drbg->generate_counter = 1;
 470     drbg->reseed_time = time(NULL);
 471     tsan_store(&drbg->reseed_counter, drbg->reseed_next_counter);
 472
 473  end:
 474     if (entropy != NULL)
 475         cleanup_entropy(drbg, entropy, entropylen);
 476     if (nonce != NULL)
 477         ossl_prov_cleanup_nonce(drbg->provctx, nonce, noncelen);
 478     if (drbg->state == EVP_RAND_STATE_READY)
 479         return 1;
 480     return 0;
 481 }
 482
 483 /*
 484  * Uninstantiate |drbg|. Must be instantiated before it can be used.
 485  *
 486  * Requires that drbg->lock is already locked for write, if non-null.
 487  *
 488  * Returns 1 on success, 0 on failure.
 489  */
 490 int ossl_prov_drbg_uninstantiate(PROV_DRBG *drbg)
 491 {
 492     drbg->state = EVP_RAND_STATE_UNINITIALISED;
 493     return 1;
 494 }
 495
 496 /*
 497  * Reseed |drbg|, mixing in the specified data
 498  *
 499  * Requires that drbg->lock is already locked for write, if non-null.
 500  *
 501  * Returns 1 on success, 0 on failure.
 502  */
 503 int ossl_prov_drbg_reseed(PROV_DRBG *drbg, int prediction_resistance,
 504                           const unsigned char *ent, size_t ent_len,
 505                           const unsigned char *adin, size_t adinlen)
 506 {
 507     unsigned char *entropy = NULL;
 508     size_t entropylen = 0;
 509
 510     if (!ossl_prov_is_running())
 511         return 0;
 512
 513     if (drbg->state != EVP_RAND_STATE_READY) {
 514         /* try to recover from previous errors */
 515         rand_drbg_restart(drbg);
 516
 517         if (drbg->state == EVP_RAND_STATE_ERROR) {
 518             ERR_raise(ERR_LIB_PROV, PROV_R_IN_ERROR_STATE);
 519             return 0;
 520         }
 521         if (drbg->state == EVP_RAND_STATE_UNINITIALISED) {
 522             ERR_raise(ERR_LIB_PROV, PROV_R_NOT_INSTANTIATED);
 523             return 0;
 524         }
 525     }
 526
 527     if (ent != NULL) {
 528         if (ent_len < drbg->min_entropylen) {
 529             ERR_raise(ERR_LIB_RAND, RAND_R_ENTROPY_OUT_OF_RANGE);
 530             drbg->state = EVP_RAND_STATE_ERROR;
 531             return 0;
 532         }
 533         if (ent_len > drbg->max_entropylen) {
 534             ERR_raise(ERR_LIB_RAND, RAND_R_ENTROPY_INPUT_TOO_LONG);
 535             drbg->state = EVP_RAND_STATE_ERROR;
 536             return 0;
 537         }
 538     }
 539
 540     if (adin == NULL) {
 541         adinlen = 0;
 542     } else if (adinlen > drbg->max_adinlen) {
 543         ERR_raise(ERR_LIB_PROV, PROV_R_ADDITIONAL_INPUT_TOO_LONG);
 544         return 0;
 545     }
 546
 547     drbg->state = EVP_RAND_STATE_ERROR;
 548
 549     drbg->reseed_next_counter = tsan_load(&drbg->reseed_counter);
 550     if (drbg->reseed_next_counter) {
 551         drbg->reseed_next_counter++;
 552         if (!drbg->reseed_next_counter)
 553             drbg->reseed_next_counter = 1;
 554     }
 555
 556     if (ent != NULL) {
 557 #ifdef FIPS_MODULE
 558         /*
 559          * NIST SP-800-90A mandates that entropy *shall not* be provided
 560          * by the consuming application. Instead the data is added as additional
 561          * input.
 562          *
 563          * (NIST SP-800-90Ar1, Sections 9.1 and 9.2)
 564          */
 565         if (!drbg->reseed(drbg, NULL, 0, ent, ent_len)) {
 566             ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_RESEED);
 567             return 0;
 568         }
 569 #else
 570         if (!drbg->reseed(drbg, ent, ent_len, adin, adinlen)) {
 571             ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_RESEED);
 572             return 0;
 573         }
 574         /* There isn't much point adding the same additional input twice */
 575         adin = NULL;
 576         adinlen = 0;
 577 #endif
 578     }
 579
 580     /* Reseed using our sources in addition */
 581     entropylen = get_entropy(drbg, &entropy, drbg->strength,
 582                              drbg->min_entropylen, drbg->max_entropylen,
 583                              prediction_resistance);
 584     if (entropylen < drbg->min_entropylen
 585             || entropylen > drbg->max_entropylen) {
 586         ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_ENTROPY);
 587         goto end;
 588     }
 589
 590     if (!drbg->reseed(drbg, entropy, entropylen, adin, adinlen))
 591         goto end;
 592
 593     drbg->state = EVP_RAND_STATE_READY;
 594     drbg->generate_counter = 1;
 595     drbg->reseed_time = time(NULL);
 596     tsan_store(&drbg->reseed_counter, drbg->reseed_next_counter);
 597     if (drbg->parent != NULL)
 598         drbg->parent_reseed_counter = get_parent_reseed_count(drbg);
 599
 600  end:
 601     cleanup_entropy(drbg, entropy, entropylen);
 602     if (drbg->state == EVP_RAND_STATE_READY)
 603         return 1;
 604     return 0;
 605 }
 606
 607 /*
 608  * Generate |outlen| bytes into the buffer at |out|.  Reseed if we need
 609  * to or if |prediction_resistance| is set.  Additional input can be
 610  * sent in |adin| and |adinlen|.
 611  *
 612  * Requires that drbg->lock is already locked for write, if non-null.
 613  *
 614  * Returns 1 on success, 0 on failure.
 615  *
 616  */
 617 int ossl_prov_drbg_generate(PROV_DRBG *drbg, unsigned char *out, size_t outlen,
 618                             unsigned int strength, int prediction_resistance,
 619                             const unsigned char *adin, size_t adinlen)
 620 {
 621     int fork_id;
 622     int reseed_required = 0;
 623
 624     if (!ossl_prov_is_running())
 625         return 0;
 626
 627     if (drbg->state != EVP_RAND_STATE_READY) {
 628         /* try to recover from previous errors */
 629         rand_drbg_restart(drbg);
 630
 631         if (drbg->state == EVP_RAND_STATE_ERROR) {
 632             ERR_raise(ERR_LIB_PROV, PROV_R_IN_ERROR_STATE);
 633             return 0;
 634         }
 635         if (drbg->state == EVP_RAND_STATE_UNINITIALISED) {
 636             ERR_raise(ERR_LIB_PROV, PROV_R_NOT_INSTANTIATED);
 637             return 0;
 638         }
 639     }
 640     if (strength > drbg->strength) {
 641         ERR_raise(ERR_LIB_PROV, PROV_R_INSUFFICIENT_DRBG_STRENGTH);
 642         return 0;
 643     }
 644
 645     if (outlen > drbg->max_request) {
 646         ERR_raise(ERR_LIB_PROV, PROV_R_REQUEST_TOO_LARGE_FOR_DRBG);
 647         return 0;
 648     }
 649     if (adinlen > drbg->max_adinlen) {
 650         ERR_raise(ERR_LIB_PROV, PROV_R_ADDITIONAL_INPUT_TOO_LONG);
 651         return 0;
 652     }
 653
 654     fork_id = openssl_get_fork_id();
 655
 656     if (drbg->fork_id != fork_id) {
 657         drbg->fork_id = fork_id;
 658         reseed_required = 1;
 659     }
 660
 661     if (drbg->reseed_interval > 0) {
 662         if (drbg->generate_counter >= drbg->reseed_interval)
 663             reseed_required = 1;
 664     }
 665     if (drbg->reseed_time_interval > 0) {
 666         time_t now = time(NULL);
 667         if (now < drbg->reseed_time
 668             || now - drbg->reseed_time >= drbg->reseed_time_interval)
 669             reseed_required = 1;
 670     }
 671     if (drbg->parent != NULL
 672             && get_parent_reseed_count(drbg) != drbg->parent_reseed_counter)
 673         reseed_required = 1;
 674
 675     if (reseed_required || prediction_resistance) {
 676         if (!ossl_prov_drbg_reseed(drbg, prediction_resistance, NULL, 0,
 677                                    adin, adinlen)) {
 678             ERR_raise(ERR_LIB_PROV, PROV_R_RESEED_ERROR);
 679             return 0;
 680         }
 681         adin = NULL;
 682         adinlen = 0;
 683     }
 684
 685     if (!drbg->generate(drbg, out, outlen, adin, adinlen)) {
 686         drbg->state = EVP_RAND_STATE_ERROR;
 687         ERR_raise(ERR_LIB_PROV, PROV_R_GENERATE_ERROR);
 688         return 0;
 689     }
 690
 691     drbg->generate_counter++;
 692
 693     return 1;
 694 }
 695
 696 /*
 697  * Restart |drbg|, using the specified entropy or additional input
 698  *
 699  * Tries its best to get the drbg instantiated by all means,
 700  * regardless of its current state.
 701  *
 702  * Optionally, a |buffer| of |len| random bytes can be passed,
 703  * which is assumed to contain at least |entropy| bits of entropy.
 704  *
 705  * If |entropy| > 0, the buffer content is used as entropy input.
 706  *
 707  * If |entropy| == 0, the buffer content is used as additional input
 708  *
 709  * Returns 1 on success, 0 on failure.
 710  *
 711  * This function is used internally only.
 712  */
 713 static int rand_drbg_restart(PROV_DRBG *drbg)
 714 {
 715     /* repair error state */
 716     if (drbg->state == EVP_RAND_STATE_ERROR)
 717         drbg->uninstantiate(drbg);
 718
 719     /* repair uninitialized state */
 720     if (drbg->state == EVP_RAND_STATE_UNINITIALISED)
 721         /* reinstantiate drbg */
 722         ossl_prov_drbg_instantiate(drbg, drbg->strength, 0, NULL, 0);
 723
 724     return drbg->state == EVP_RAND_STATE_READY;
 725 }
 726
 727 /* Provider support from here down */
 728 static const OSSL_DISPATCH *find_call(const OSSL_DISPATCH *dispatch,
 729                                       int function)
 730 {
 731     if (dispatch != NULL)
 732         while (dispatch->function_id != 0) {
 733             if (dispatch->function_id == function)
 734                 return dispatch;
 735             dispatch++;
 736         }
 737     return NULL;
 738 }
 739
 740 int ossl_drbg_enable_locking(void *vctx)
 741 {
 742     PROV_DRBG *drbg = vctx;
 743
 744     if (drbg != NULL && drbg->lock == NULL) {
 745         if (drbg->parent_enable_locking != NULL)
 746             if (!drbg->parent_enable_locking(drbg->parent)) {
 747                 ERR_raise(ERR_LIB_PROV, PROV_R_PARENT_LOCKING_NOT_ENABLED);
 748                 return 0;
 749             }
 750         drbg->lock = CRYPTO_THREAD_lock_new();
 751         if (drbg->lock == NULL) {
 752             ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_CREATE_LOCK);
 753             return 0;
 754         }
 755     }
 756     return 1;
 757 }
 758
 759 /*
 760  * Allocate memory and initialize a new DRBG. The DRBG is allocated on
 761  * the secure heap if |secure| is nonzero and the secure heap is enabled.
 762  * The |parent|, if not NULL, will be used as random source for reseeding.
 763  * This also requires the parent's provider context and the parent's lock.
 764  *
 765  * Returns a pointer to the new DRBG instance on success, NULL on failure.
 766  */
 767 PROV_DRBG *ossl_rand_drbg_new
 768     (void *provctx, void *parent, const OSSL_DISPATCH *p_dispatch,
 769      int (*dnew)(PROV_DRBG *ctx),
 770      int (*instantiate)(PROV_DRBG *drbg,
 771                         const unsigned char *entropy, size_t entropylen,
 772                         const unsigned char *nonce, size_t noncelen,
 773                         const unsigned char *pers, size_t perslen),
 774      int (*uninstantiate)(PROV_DRBG *ctx),
 775      int (*reseed)(PROV_DRBG *drbg, const unsigned char *ent, size_t ent_len,
 776                    const unsigned char *adin, size_t adin_len),
 777      int (*generate)(PROV_DRBG *, unsigned char *out, size_t outlen,
 778                      const unsigned char *adin, size_t adin_len))
 779 {
 780     PROV_DRBG *drbg;
 781     unsigned int p_str;
 782     const OSSL_DISPATCH *pfunc;
 783
 784     if (!ossl_prov_is_running())
 785         return NULL;
 786
 787     drbg = OPENSSL_zalloc(sizeof(*drbg));
 788     if (drbg == NULL) {
 789         ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
 790         return NULL;
 791     }
 792
 793     drbg->provctx = provctx;
 794     drbg->instantiate = instantiate;
 795     drbg->uninstantiate = uninstantiate;
 796     drbg->reseed = reseed;
 797     drbg->generate = generate;
 798     drbg->fork_id = openssl_get_fork_id();
 799
 800     /* Extract parent's functions */
 801     drbg->parent = parent;
 802     if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_ENABLE_LOCKING)) != NULL)
 803         drbg->parent_enable_locking = OSSL_FUNC_rand_enable_locking(pfunc);
 804     if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_LOCK)) != NULL)
 805         drbg->parent_lock = OSSL_FUNC_rand_lock(pfunc);
 806     if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_UNLOCK)) != NULL)
 807         drbg->parent_unlock = OSSL_FUNC_rand_unlock(pfunc);
 808     if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_GET_CTX_PARAMS)) != NULL)
 809         drbg->parent_get_ctx_params = OSSL_FUNC_rand_get_ctx_params(pfunc);
 810     if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_NONCE)) != NULL)
 811         drbg->parent_nonce = OSSL_FUNC_rand_nonce(pfunc);
 812     if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_GET_SEED)) != NULL)
 813         drbg->parent_get_seed = OSSL_FUNC_rand_get_seed(pfunc);
 814     if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_CLEAR_SEED)) != NULL)
 815         drbg->parent_clear_seed = OSSL_FUNC_rand_clear_seed(pfunc);
 816
 817     /* Set some default maximums up */
 818     drbg->max_entropylen = DRBG_MAX_LENGTH;
 819     drbg->max_noncelen = DRBG_MAX_LENGTH;
 820     drbg->max_perslen = DRBG_MAX_LENGTH;
 821     drbg->max_adinlen = DRBG_MAX_LENGTH;
 822     drbg->generate_counter = 1;
 823     drbg->reseed_counter = 1;
 824     drbg->reseed_interval = RESEED_INTERVAL;
 825     drbg->reseed_time_interval = TIME_INTERVAL;
 826
 827     if (!dnew(drbg))
 828         goto err;
 829
 830     if (parent != NULL) {
 831         if (!get_parent_strength(drbg, &p_str))
 832             goto err;
 833         if (drbg->strength > p_str) {
 834             /*
 835              * We currently don't support the algorithm from NIST SP 800-90C
 836              * 10.1.2 to use a weaker DRBG as source
 837              */
 838             ERR_raise(ERR_LIB_PROV, PROV_R_PARENT_STRENGTH_TOO_WEAK);
 839             goto err;
 840         }
 841     }
 842     return drbg;
 843
 844  err:
 845     ossl_rand_drbg_free(drbg);
 846     return NULL;
 847 }
 848
 849 void ossl_rand_drbg_free(PROV_DRBG *drbg)
 850 {
 851     if (drbg == NULL)
 852         return;
 853
 854     CRYPTO_THREAD_lock_free(drbg->lock);
 855     OPENSSL_free(drbg);
 856 }
 857
 858 int ossl_drbg_get_ctx_params(PROV_DRBG *drbg, OSSL_PARAM params[])
 859 {
 860     OSSL_PARAM *p;
 861
 862     p = OSSL_PARAM_locate(params, OSSL_RAND_PARAM_STATE);
 863     if (p != NULL && !OSSL_PARAM_set_int(p, drbg->state))
 864         return 0;
 865
 866     p = OSSL_PARAM_locate(params, OSSL_RAND_PARAM_STRENGTH);
 867     if (p != NULL && !OSSL_PARAM_set_int(p, drbg->strength))
 868         return 0;
 869
 870     p = OSSL_PARAM_locate(params, OSSL_RAND_PARAM_MAX_REQUEST);
 871     if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->max_request))
 872         return 0;
 873
 874     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MIN_ENTROPYLEN);
 875     if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->min_entropylen))
 876         return 0;
 877
 878     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MAX_ENTROPYLEN);
 879     if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->max_entropylen))
 880         return 0;
 881
 882     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MIN_NONCELEN);
 883     if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->min_noncelen))
 884         return 0;
 885
 886     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MAX_NONCELEN);
 887     if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->max_noncelen))
 888         return 0;
 889
 890     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MAX_PERSLEN);
 891     if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->max_perslen))
 892         return 0;
 893
 894     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MAX_ADINLEN);
 895     if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->max_adinlen))
 896         return 0;
 897
 898     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_RESEED_REQUESTS);
 899     if (p != NULL && !OSSL_PARAM_set_uint(p, drbg->reseed_interval))
 900         return 0;
 901
 902     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_RESEED_TIME);
 903     if (p != NULL && !OSSL_PARAM_set_time_t(p, drbg->reseed_time))
 904         return 0;
 905
 906     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL);
 907     if (p != NULL && !OSSL_PARAM_set_time_t(p, drbg->reseed_time_interval))
 908         return 0;
 909
 910     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_RESEED_COUNTER);
 911     if (p != NULL
 912             && !OSSL_PARAM_set_uint(p, tsan_load(&drbg->reseed_counter)))
 913         return 0;
 914     return 1;
 915 }
 916
 917 int ossl_drbg_set_ctx_params(PROV_DRBG *drbg, const OSSL_PARAM params[])
 918 {
 919     const OSSL_PARAM *p;
 920
 921     p = OSSL_PARAM_locate_const(params, OSSL_DRBG_PARAM_RESEED_REQUESTS);
 922     if (p != NULL && !OSSL_PARAM_get_uint(p, &drbg->reseed_interval))
 923         return 0;
 924
 925     p = OSSL_PARAM_locate_const(params, OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL);
 926     if (p != NULL && !OSSL_PARAM_get_time_t(p, &drbg->reseed_time_interval))
 927         return 0;
 928     return 1;
 929 }