providers/implementations/rands/drbg.c

   1 /*
   2  * Copyright 2011-2022 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 #include "crypto/context.h"
  25
  26 /*
  27  * Support framework for NIST SP 800-90A DRBG
  28  *
  29  * See manual page PROV_DRBG(7) for a general overview.
  30  *
  31  * The OpenSSL model is to have new and free functions, and that new
  32  * does all initialization.  That is not the NIST model, which has
  33  * instantiation and un-instantiate, and re-use within a new/free
  34  * lifecycle.  (No doubt this comes from the desire to support hardware
  35  * DRBG, where allocation of resources on something like an HSM is
  36  * a much bigger deal than just re-setting an allocated resource.)
  37  */
  38
  39 /* NIST SP 800-90A DRBG recommends the use of a personalization string. */
  40 static const char ossl_pers_string[] = DRBG_DEFAULT_PERS_STRING;
  41
  42 static const OSSL_DISPATCH *find_call(const OSSL_DISPATCH *dispatch,
  43                                       int function);
  44
  45 static int rand_drbg_restart(PROV_DRBG *drbg);
  46
  47 int ossl_drbg_lock(void *vctx)
  48 {
  49     PROV_DRBG *drbg = vctx;
  50
  51     if (drbg == NULL || drbg->lock == NULL)
  52         return 1;
  53     return CRYPTO_THREAD_write_lock(drbg->lock);
  54 }
  55
  56 void ossl_drbg_unlock(void *vctx)
  57 {
  58     PROV_DRBG *drbg = vctx;
  59
  60     if (drbg != NULL && drbg->lock != NULL)
  61         CRYPTO_THREAD_unlock(drbg->lock);
  62 }
  63
  64 static int ossl_drbg_lock_parent(PROV_DRBG *drbg)
  65 {
  66     void *parent = drbg->parent;
  67
  68     if (parent != NULL
  69             && drbg->parent_lock != NULL
  70             && !drbg->parent_lock(parent)) {
  71         ERR_raise(ERR_LIB_PROV, PROV_R_PARENT_LOCKING_NOT_ENABLED);
  72         return 0;
  73     }
  74     return 1;
  75 }
  76
  77 static void ossl_drbg_unlock_parent(PROV_DRBG *drbg)
  78 {
  79     void *parent = drbg->parent;
  80
  81     if (parent != NULL && drbg->parent_unlock != NULL)
  82         drbg->parent_unlock(parent);
  83 }
  84
  85 static int get_parent_strength(PROV_DRBG *drbg, unsigned int *str)
  86 {
  87     OSSL_PARAM params[2] = { OSSL_PARAM_END, OSSL_PARAM_END };
  88     void *parent = drbg->parent;
  89     int res;
  90
  91     if (drbg->parent_get_ctx_params == NULL) {
  92         ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_GET_PARENT_STRENGTH);
  93         return 0;
  94     }
  95
  96     *params = OSSL_PARAM_construct_uint(OSSL_RAND_PARAM_STRENGTH, str);
  97     if (!ossl_drbg_lock_parent(drbg)) {
  98         ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_LOCK_PARENT);
  99         return 0;
 100     }
 101     res = drbg->parent_get_ctx_params(parent, params);
 102     ossl_drbg_unlock_parent(drbg);
 103     if (!res) {
 104         ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_GET_PARENT_STRENGTH);
 105         return 0;
 106     }
 107     return 1;
 108 }
 109
 110 static unsigned int get_parent_reseed_count(PROV_DRBG *drbg)
 111 {
 112     OSSL_PARAM params[2] = { OSSL_PARAM_END, OSSL_PARAM_END };
 113     void *parent = drbg->parent;
 114     unsigned int r = 0;
 115
 116     *params = OSSL_PARAM_construct_uint(OSSL_DRBG_PARAM_RESEED_COUNTER, &r);
 117     if (!ossl_drbg_lock_parent(drbg)) {
 118         ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_LOCK_PARENT);
 119         goto err;
 120     }
 121     if (!drbg->parent_get_ctx_params(parent, params))
 122         r = 0;
 123     ossl_drbg_unlock_parent(drbg);
 124     return r;
 125
 126  err:
 127     r = tsan_load(&drbg->reseed_counter) - 2;
 128     if (r == 0)
 129         r = UINT_MAX;
 130     return r;
 131 }
 132
 133 /*
 134  * Implements the get_entropy() callback
 135  *
 136  * If the DRBG has a parent, then the required amount of entropy input
 137  * is fetched using the parent's ossl_prov_drbg_generate().
 138  *
 139  * Otherwise, the entropy is polled from the system entropy sources
 140  * using ossl_pool_acquire_entropy().
 141  *
 142  * If a random pool has been added to the DRBG using RAND_add(), then
 143  * its entropy will be used up first.
 144  */
 145 size_t ossl_drbg_get_seed(void *vdrbg, unsigned char **pout,
 146                           int entropy, size_t min_len,
 147                           size_t max_len, int prediction_resistance,
 148                           const unsigned char *adin, size_t adin_len)
 149 {
 150     PROV_DRBG *drbg = (PROV_DRBG *)vdrbg;
 151     size_t bytes_needed;
 152     unsigned char *buffer;
 153
 154     /* Figure out how many bytes we need */
 155     bytes_needed = entropy >= 0 ? (entropy + 7) / 8 : 0;
 156     if (bytes_needed < min_len)
 157         bytes_needed = min_len;
 158     if (bytes_needed > max_len)
 159         bytes_needed = max_len;
 160
 161     /* Allocate storage */
 162     buffer = OPENSSL_secure_malloc(bytes_needed);
 163     if (buffer == NULL)
 164         return 0;
 165
 166     /*
 167      * Get random data.  Include our DRBG address as
 168      * additional input, in order to provide a distinction between
 169      * different DRBG child instances.
 170      *
 171      * Note: using the sizeof() operator on a pointer triggers
 172      *       a warning in some static code analyzers, but it's
 173      *       intentional and correct here.
 174      */
 175     if (!ossl_prov_drbg_generate(drbg, buffer, bytes_needed,
 176                                  drbg->strength, prediction_resistance,
 177                                  (unsigned char *)&drbg, sizeof(drbg))) {
 178         OPENSSL_secure_clear_free(buffer, bytes_needed);
 179         ERR_raise(ERR_LIB_PROV, PROV_R_GENERATE_ERROR);
 180         return 0;
 181     }
 182     *pout = buffer;
 183     return bytes_needed;
 184 }
 185
 186 /* Implements the cleanup_entropy() callback */
 187 void ossl_drbg_clear_seed(ossl_unused void *vdrbg,
 188                           unsigned char *out, size_t outlen)
 189 {
 190     OPENSSL_secure_clear_free(out, outlen);
 191 }
 192
 193 static size_t get_entropy(PROV_DRBG *drbg, unsigned char **pout, int entropy,
 194                           size_t min_len, size_t max_len,
 195                           int prediction_resistance)
 196 {
 197     size_t bytes;
 198     unsigned int p_str;
 199
 200     if (drbg->parent == NULL)
 201 #ifdef FIPS_MODULE
 202         return ossl_crngt_get_entropy(drbg, pout, entropy, min_len, max_len,
 203                                       prediction_resistance);
 204 #else
 205         return ossl_prov_get_entropy(drbg->provctx, pout, entropy, min_len,
 206                                      max_len);
 207 #endif
 208
 209     if (drbg->parent_get_seed == NULL) {
 210         ERR_raise(ERR_LIB_PROV, PROV_R_PARENT_CANNOT_SUPPLY_ENTROPY_SEED);
 211         return 0;
 212     }
 213     if (!get_parent_strength(drbg, &p_str))
 214         return 0;
 215     if (drbg->strength > p_str) {
 216         /*
 217          * We currently don't support the algorithm from NIST SP 800-90C
 218          * 10.1.2 to use a weaker DRBG as source
 219          */
 220         ERR_raise(ERR_LIB_PROV, PROV_R_PARENT_STRENGTH_TOO_WEAK);
 221         return 0;
 222     }
 223
 224     /*
 225      * Our lock is already held, but we need to lock our parent before
 226      * generating bits from it.  Note: taking the lock will be a no-op
 227      * if locking is not required (while drbg->parent->lock == NULL).
 228      */
 229     if (!ossl_drbg_lock_parent(drbg))
 230         return 0;
 231     /*
 232      * Get random data from parent.  Include our DRBG address as
 233      * additional input, in order to provide a distinction between
 234      * different DRBG child instances.
 235      *
 236      * Note: using the sizeof() operator on a pointer triggers
 237      *       a warning in some static code analyzers, but it's
 238      *       intentional and correct here.
 239      */
 240     bytes = drbg->parent_get_seed(drbg->parent, pout, drbg->strength,
 241                                   min_len, max_len, prediction_resistance,
 242                                   (unsigned char *)&drbg, sizeof(drbg));
 243     ossl_drbg_unlock_parent(drbg);
 244     return bytes;
 245 }
 246
 247 static void cleanup_entropy(PROV_DRBG *drbg, unsigned char *out, size_t outlen)
 248 {
 249     if (drbg->parent == NULL) {
 250 #ifdef FIPS_MODULE
 251         ossl_crngt_cleanup_entropy(drbg, out, outlen);
 252 #else
 253         ossl_prov_cleanup_entropy(drbg->provctx, out, outlen);
 254 #endif
 255     } else if (drbg->parent_clear_seed != NULL) {
 256         if (!ossl_drbg_lock_parent(drbg))
 257             return;
 258         drbg->parent_clear_seed(drbg, out, outlen);
 259         ossl_drbg_unlock_parent(drbg);
 260     }
 261 }
 262
 263 #ifndef PROV_RAND_GET_RANDOM_NONCE
 264 typedef struct prov_drbg_nonce_global_st {
 265     CRYPTO_RWLOCK *rand_nonce_lock;
 266     int rand_nonce_count;
 267 } PROV_DRBG_NONCE_GLOBAL;
 268
 269 /*
 270  * drbg_ossl_ctx_new() calls drgb_setup() which calls rand_drbg_get_nonce()
 271  * which needs to get the rand_nonce_lock out of the OSSL_LIB_CTX...but since
 272  * drbg_ossl_ctx_new() hasn't finished running yet we need the rand_nonce_lock
 273  * to be in a different global data object. Otherwise we will go into an
 274  * infinite recursion loop.
 275  */
 276 void *ossl_prov_drbg_nonce_ctx_new(OSSL_LIB_CTX *libctx)
 277 {
 278     PROV_DRBG_NONCE_GLOBAL *dngbl = OPENSSL_zalloc(sizeof(*dngbl));
 279
 280     if (dngbl == NULL)
 281         return NULL;
 282
 283     dngbl->rand_nonce_lock = CRYPTO_THREAD_lock_new();
 284     if (dngbl->rand_nonce_lock == NULL) {
 285         OPENSSL_free(dngbl);
 286         return NULL;
 287     }
 288
 289     return dngbl;
 290 }
 291
 292 void ossl_prov_drbg_nonce_ctx_free(void *vdngbl)
 293 {
 294     PROV_DRBG_NONCE_GLOBAL *dngbl = vdngbl;
 295
 296     if (dngbl == NULL)
 297         return;
 298
 299     CRYPTO_THREAD_lock_free(dngbl->rand_nonce_lock);
 300
 301     OPENSSL_free(dngbl);
 302 }
 303
 304 /* Get a nonce from the operating system */
 305 static size_t prov_drbg_get_nonce(PROV_DRBG *drbg, unsigned char **pout,
 306                                   size_t min_len, size_t max_len)
 307 {
 308     size_t ret = 0, n;
 309     unsigned char *buf = NULL;
 310     OSSL_LIB_CTX *libctx = ossl_prov_ctx_get0_libctx(drbg->provctx);
 311     PROV_DRBG_NONCE_GLOBAL *dngbl
 312         = ossl_lib_ctx_get_data(libctx, OSSL_LIB_CTX_DRBG_NONCE_INDEX);
 313     struct {
 314         void *drbg;
 315         int count;
 316     } data;
 317
 318     if (dngbl == NULL)
 319         return 0;
 320
 321     if (drbg->parent != NULL && drbg->parent_nonce != NULL) {
 322         n = drbg->parent_nonce(drbg->parent, NULL, 0, drbg->min_noncelen,
 323                                drbg->max_noncelen);
 324         if (n > 0 && (buf = OPENSSL_malloc(n)) != NULL) {
 325             ret = drbg->parent_nonce(drbg->parent, buf, 0,
 326                                      drbg->min_noncelen, drbg->max_noncelen);
 327             if (ret == n) {
 328                 *pout = buf;
 329                 return ret;
 330             }
 331             OPENSSL_free(buf);
 332         }
 333     }
 334
 335     /* Use the built in nonce source plus some of our specifics */
 336     memset(&data, 0, sizeof(data));
 337     data.drbg = drbg;
 338     CRYPTO_atomic_add(&dngbl->rand_nonce_count, 1, &data.count,
 339                       dngbl->rand_nonce_lock);
 340     return ossl_prov_get_nonce(drbg->provctx, pout, min_len, max_len,
 341                                &data, sizeof(data));
 342 }
 343 #endif /* PROV_RAND_GET_RANDOM_NONCE */
 344
 345 /*
 346  * Instantiate |drbg|, after it has been initialized.  Use |pers| and
 347  * |perslen| as prediction-resistance input.
 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 ossl_prov_drbg_instantiate(PROV_DRBG *drbg, unsigned int strength,
 354                                int prediction_resistance,
 355                                const unsigned char *pers, size_t perslen)
 356 {
 357     unsigned char *nonce = NULL, *entropy = NULL;
 358     size_t noncelen = 0, entropylen = 0;
 359     size_t min_entropy, min_entropylen, max_entropylen;
 360
 361     if (strength > drbg->strength) {
 362         ERR_raise(ERR_LIB_PROV, PROV_R_INSUFFICIENT_DRBG_STRENGTH);
 363         goto end;
 364     }
 365     min_entropy = drbg->strength;
 366     min_entropylen = drbg->min_entropylen;
 367     max_entropylen = drbg->max_entropylen;
 368
 369     if (pers == NULL) {
 370         pers = (const unsigned char *)ossl_pers_string;
 371         perslen = sizeof(ossl_pers_string);
 372     }
 373     if (perslen > drbg->max_perslen) {
 374         ERR_raise(ERR_LIB_PROV, PROV_R_PERSONALISATION_STRING_TOO_LONG);
 375         goto end;
 376     }
 377
 378     if (drbg->state != EVP_RAND_STATE_UNINITIALISED) {
 379         if (drbg->state == EVP_RAND_STATE_ERROR)
 380             ERR_raise(ERR_LIB_PROV, PROV_R_IN_ERROR_STATE);
 381         else
 382             ERR_raise(ERR_LIB_PROV, PROV_R_ALREADY_INSTANTIATED);
 383         goto end;
 384     }
 385
 386     drbg->state = EVP_RAND_STATE_ERROR;
 387
 388     if (drbg->min_noncelen > 0) {
 389         if (drbg->parent_nonce != NULL) {
 390             noncelen = drbg->parent_nonce(drbg->parent, NULL, drbg->strength,
 391                                           drbg->min_noncelen,
 392                                           drbg->max_noncelen);
 393             if (noncelen == 0) {
 394                 ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_NONCE);
 395                 goto end;
 396             }
 397             nonce = OPENSSL_malloc(noncelen);
 398             if (nonce == NULL) {
 399                 ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_NONCE);
 400                 goto end;
 401             }
 402             if (noncelen != drbg->parent_nonce(drbg->parent, nonce,
 403                                                drbg->strength,
 404                                                drbg->min_noncelen,
 405                                                drbg->max_noncelen)) {
 406                 ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_NONCE);
 407                 goto end;
 408             }
 409 #ifndef PROV_RAND_GET_RANDOM_NONCE
 410         } else if (drbg->parent != NULL) {
 411 #endif
 412             /*
 413              * NIST SP800-90Ar1 section 9.1 says you can combine getting
 414              * the entropy and nonce in 1 call by increasing the entropy
 415              * with 50% and increasing the minimum length to accommodate
 416              * the length of the nonce. We do this in case a nonce is
 417              * required and there is no parental nonce capability.
 418              */
 419             min_entropy += drbg->strength / 2;
 420             min_entropylen += drbg->min_noncelen;
 421             max_entropylen += drbg->max_noncelen;
 422         }
 423 #ifndef PROV_RAND_GET_RANDOM_NONCE
 424         else { /* parent == NULL */
 425             noncelen = prov_drbg_get_nonce(drbg, &nonce, drbg->min_noncelen,
 426                                            drbg->max_noncelen);
 427             if (noncelen < drbg->min_noncelen
 428                     || noncelen > drbg->max_noncelen) {
 429                 ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_NONCE);
 430                 goto end;
 431             }
 432         }
 433 #endif
 434     }
 435
 436     drbg->reseed_next_counter = tsan_load(&drbg->reseed_counter);
 437     if (drbg->reseed_next_counter) {
 438         drbg->reseed_next_counter++;
 439         if (!drbg->reseed_next_counter)
 440             drbg->reseed_next_counter = 1;
 441     }
 442
 443     entropylen = get_entropy(drbg, &entropy, min_entropy,
 444                              min_entropylen, max_entropylen,
 445                              prediction_resistance);
 446     if (entropylen < min_entropylen
 447             || entropylen > max_entropylen) {
 448         ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_ENTROPY);
 449         goto end;
 450     }
 451
 452     if (!drbg->instantiate(drbg, entropy, entropylen, nonce, noncelen,
 453                            pers, perslen)) {
 454         cleanup_entropy(drbg, entropy, entropylen);
 455         ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_INSTANTIATING_DRBG);
 456         goto end;
 457     }
 458     cleanup_entropy(drbg, entropy, entropylen);
 459
 460     drbg->state = EVP_RAND_STATE_READY;
 461     drbg->generate_counter = 1;
 462     drbg->reseed_time = time(NULL);
 463     tsan_store(&drbg->reseed_counter, drbg->reseed_next_counter);
 464
 465  end:
 466     if (nonce != NULL)
 467         ossl_prov_cleanup_nonce(drbg->provctx, nonce, noncelen);
 468     if (drbg->state == EVP_RAND_STATE_READY)
 469         return 1;
 470     return 0;
 471 }
 472
 473 /*
 474  * Uninstantiate |drbg|. Must be instantiated before it can be used.
 475  *
 476  * Requires that drbg->lock is already locked for write, if non-null.
 477  *
 478  * Returns 1 on success, 0 on failure.
 479  */
 480 int ossl_prov_drbg_uninstantiate(PROV_DRBG *drbg)
 481 {
 482     drbg->state = EVP_RAND_STATE_UNINITIALISED;
 483     return 1;
 484 }
 485
 486 /*
 487  * Reseed |drbg|, mixing in the specified data
 488  *
 489  * Requires that drbg->lock is already locked for write, if non-null.
 490  *
 491  * Returns 1 on success, 0 on failure.
 492  */
 493 int ossl_prov_drbg_reseed(PROV_DRBG *drbg, int prediction_resistance,
 494                           const unsigned char *ent, size_t ent_len,
 495                           const unsigned char *adin, size_t adinlen)
 496 {
 497     unsigned char *entropy = NULL;
 498     size_t entropylen = 0;
 499
 500     if (!ossl_prov_is_running())
 501         return 0;
 502
 503     if (drbg->state != EVP_RAND_STATE_READY) {
 504         /* try to recover from previous errors */
 505         rand_drbg_restart(drbg);
 506
 507         if (drbg->state == EVP_RAND_STATE_ERROR) {
 508             ERR_raise(ERR_LIB_PROV, PROV_R_IN_ERROR_STATE);
 509             return 0;
 510         }
 511         if (drbg->state == EVP_RAND_STATE_UNINITIALISED) {
 512             ERR_raise(ERR_LIB_PROV, PROV_R_NOT_INSTANTIATED);
 513             return 0;
 514         }
 515     }
 516
 517     if (ent != NULL) {
 518         if (ent_len < drbg->min_entropylen) {
 519             ERR_raise(ERR_LIB_RAND, RAND_R_ENTROPY_OUT_OF_RANGE);
 520             drbg->state = EVP_RAND_STATE_ERROR;
 521             return 0;
 522         }
 523         if (ent_len > drbg->max_entropylen) {
 524             ERR_raise(ERR_LIB_RAND, RAND_R_ENTROPY_INPUT_TOO_LONG);
 525             drbg->state = EVP_RAND_STATE_ERROR;
 526             return 0;
 527         }
 528     }
 529
 530     if (adin == NULL) {
 531         adinlen = 0;
 532     } else if (adinlen > drbg->max_adinlen) {
 533         ERR_raise(ERR_LIB_PROV, PROV_R_ADDITIONAL_INPUT_TOO_LONG);
 534         return 0;
 535     }
 536
 537     drbg->state = EVP_RAND_STATE_ERROR;
 538
 539     drbg->reseed_next_counter = tsan_load(&drbg->reseed_counter);
 540     if (drbg->reseed_next_counter) {
 541         drbg->reseed_next_counter++;
 542         if (!drbg->reseed_next_counter)
 543             drbg->reseed_next_counter = 1;
 544     }
 545
 546     if (ent != NULL) {
 547 #ifdef FIPS_MODULE
 548         /*
 549          * NIST SP-800-90A mandates that entropy *shall not* be provided
 550          * by the consuming application. Instead the data is added as additional
 551          * input.
 552          *
 553          * (NIST SP-800-90Ar1, Sections 9.1 and 9.2)
 554          */
 555         if (!drbg->reseed(drbg, NULL, 0, ent, ent_len)) {
 556             ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_RESEED);
 557             return 0;
 558         }
 559 #else
 560         if (!drbg->reseed(drbg, ent, ent_len, adin, adinlen)) {
 561             ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_RESEED);
 562             return 0;
 563         }
 564         /* There isn't much point adding the same additional input twice */
 565         adin = NULL;
 566         adinlen = 0;
 567 #endif
 568     }
 569
 570     /* Reseed using our sources in addition */
 571     entropylen = get_entropy(drbg, &entropy, drbg->strength,
 572                              drbg->min_entropylen, drbg->max_entropylen,
 573                              prediction_resistance);
 574     if (entropylen < drbg->min_entropylen
 575             || entropylen > drbg->max_entropylen) {
 576         ERR_raise(ERR_LIB_PROV, PROV_R_ERROR_RETRIEVING_ENTROPY);
 577         goto end;
 578     }
 579
 580     if (!drbg->reseed(drbg, entropy, entropylen, adin, adinlen))
 581         goto end;
 582
 583     drbg->state = EVP_RAND_STATE_READY;
 584     drbg->generate_counter = 1;
 585     drbg->reseed_time = time(NULL);
 586     tsan_store(&drbg->reseed_counter, drbg->reseed_next_counter);
 587     if (drbg->parent != NULL)
 588         drbg->parent_reseed_counter = get_parent_reseed_count(drbg);
 589
 590  end:
 591     cleanup_entropy(drbg, entropy, entropylen);
 592     if (drbg->state == EVP_RAND_STATE_READY)
 593         return 1;
 594     return 0;
 595 }
 596
 597 /*
 598  * Generate |outlen| bytes into the buffer at |out|.  Reseed if we need
 599  * to or if |prediction_resistance| is set.  Additional input can be
 600  * sent in |adin| and |adinlen|.
 601  *
 602  * Requires that drbg->lock is already locked for write, if non-null.
 603  *
 604  * Returns 1 on success, 0 on failure.
 605  *
 606  */
 607 int ossl_prov_drbg_generate(PROV_DRBG *drbg, unsigned char *out, size_t outlen,
 608                             unsigned int strength, int prediction_resistance,
 609                             const unsigned char *adin, size_t adinlen)
 610 {
 611     int fork_id;
 612     int reseed_required = 0;
 613
 614     if (!ossl_prov_is_running())
 615         return 0;
 616
 617     if (drbg->state != EVP_RAND_STATE_READY) {
 618         /* try to recover from previous errors */
 619         rand_drbg_restart(drbg);
 620
 621         if (drbg->state == EVP_RAND_STATE_ERROR) {
 622             ERR_raise(ERR_LIB_PROV, PROV_R_IN_ERROR_STATE);
 623             return 0;
 624         }
 625         if (drbg->state == EVP_RAND_STATE_UNINITIALISED) {
 626             ERR_raise(ERR_LIB_PROV, PROV_R_NOT_INSTANTIATED);
 627             return 0;
 628         }
 629     }
 630     if (strength > drbg->strength) {
 631         ERR_raise(ERR_LIB_PROV, PROV_R_INSUFFICIENT_DRBG_STRENGTH);
 632         return 0;
 633     }
 634
 635     if (outlen > drbg->max_request) {
 636         ERR_raise(ERR_LIB_PROV, PROV_R_REQUEST_TOO_LARGE_FOR_DRBG);
 637         return 0;
 638     }
 639     if (adinlen > drbg->max_adinlen) {
 640         ERR_raise(ERR_LIB_PROV, PROV_R_ADDITIONAL_INPUT_TOO_LONG);
 641         return 0;
 642     }
 643
 644     fork_id = openssl_get_fork_id();
 645
 646     if (drbg->fork_id != fork_id) {
 647         drbg->fork_id = fork_id;
 648         reseed_required = 1;
 649     }
 650
 651     if (drbg->reseed_interval > 0) {
 652         if (drbg->generate_counter >= drbg->reseed_interval)
 653             reseed_required = 1;
 654     }
 655     if (drbg->reseed_time_interval > 0) {
 656         time_t now = time(NULL);
 657         if (now < drbg->reseed_time
 658             || now - drbg->reseed_time >= drbg->reseed_time_interval)
 659             reseed_required = 1;
 660     }
 661     if (drbg->parent != NULL
 662             && get_parent_reseed_count(drbg) != drbg->parent_reseed_counter)
 663         reseed_required = 1;
 664
 665     if (reseed_required || prediction_resistance) {
 666         if (!ossl_prov_drbg_reseed(drbg, prediction_resistance, NULL, 0,
 667                                    adin, adinlen)) {
 668             ERR_raise(ERR_LIB_PROV, PROV_R_RESEED_ERROR);
 669             return 0;
 670         }
 671         adin = NULL;
 672         adinlen = 0;
 673     }
 674
 675     if (!drbg->generate(drbg, out, outlen, adin, adinlen)) {
 676         drbg->state = EVP_RAND_STATE_ERROR;
 677         ERR_raise(ERR_LIB_PROV, PROV_R_GENERATE_ERROR);
 678         return 0;
 679     }
 680
 681     drbg->generate_counter++;
 682
 683     return 1;
 684 }
 685
 686 /*
 687  * Restart |drbg|, using the specified entropy or additional input
 688  *
 689  * Tries its best to get the drbg instantiated by all means,
 690  * regardless of its current state.
 691  *
 692  * Optionally, a |buffer| of |len| random bytes can be passed,
 693  * which is assumed to contain at least |entropy| bits of entropy.
 694  *
 695  * If |entropy| > 0, the buffer content is used as entropy input.
 696  *
 697  * If |entropy| == 0, the buffer content is used as additional input
 698  *
 699  * Returns 1 on success, 0 on failure.
 700  *
 701  * This function is used internally only.
 702  */
 703 static int rand_drbg_restart(PROV_DRBG *drbg)
 704 {
 705     /* repair error state */
 706     if (drbg->state == EVP_RAND_STATE_ERROR)
 707         drbg->uninstantiate(drbg);
 708
 709     /* repair uninitialized state */
 710     if (drbg->state == EVP_RAND_STATE_UNINITIALISED)
 711         /* reinstantiate drbg */
 712         ossl_prov_drbg_instantiate(drbg, drbg->strength, 0, NULL, 0);
 713
 714     return drbg->state == EVP_RAND_STATE_READY;
 715 }
 716
 717 /* Provider support from here down */
 718 static const OSSL_DISPATCH *find_call(const OSSL_DISPATCH *dispatch,
 719                                       int function)
 720 {
 721     if (dispatch != NULL)
 722         while (dispatch->function_id != 0) {
 723             if (dispatch->function_id == function)
 724                 return dispatch;
 725             dispatch++;
 726         }
 727     return NULL;
 728 }
 729
 730 int ossl_drbg_enable_locking(void *vctx)
 731 {
 732     PROV_DRBG *drbg = vctx;
 733
 734     if (drbg != NULL && drbg->lock == NULL) {
 735         if (drbg->parent_enable_locking != NULL)
 736             if (!drbg->parent_enable_locking(drbg->parent)) {
 737                 ERR_raise(ERR_LIB_PROV, PROV_R_PARENT_LOCKING_NOT_ENABLED);
 738                 return 0;
 739             }
 740         drbg->lock = CRYPTO_THREAD_lock_new();
 741         if (drbg->lock == NULL) {
 742             ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_CREATE_LOCK);
 743             return 0;
 744         }
 745     }
 746     return 1;
 747 }
 748
 749 /*
 750  * Allocate memory and initialize a new DRBG. The DRBG is allocated on
 751  * the secure heap if |secure| is nonzero and the secure heap is enabled.
 752  * The |parent|, if not NULL, will be used as random source for reseeding.
 753  * This also requires the parent's provider context and the parent's lock.
 754  *
 755  * Returns a pointer to the new DRBG instance on success, NULL on failure.
 756  */
 757 PROV_DRBG *ossl_rand_drbg_new
 758     (void *provctx, void *parent, const OSSL_DISPATCH *p_dispatch,
 759      int (*dnew)(PROV_DRBG *ctx),
 760      int (*instantiate)(PROV_DRBG *drbg,
 761                         const unsigned char *entropy, size_t entropylen,
 762                         const unsigned char *nonce, size_t noncelen,
 763                         const unsigned char *pers, size_t perslen),
 764      int (*uninstantiate)(PROV_DRBG *ctx),
 765      int (*reseed)(PROV_DRBG *drbg, const unsigned char *ent, size_t ent_len,
 766                    const unsigned char *adin, size_t adin_len),
 767      int (*generate)(PROV_DRBG *, unsigned char *out, size_t outlen,
 768                      const unsigned char *adin, size_t adin_len))
 769 {
 770     PROV_DRBG *drbg;
 771     unsigned int p_str;
 772     const OSSL_DISPATCH *pfunc;
 773
 774     if (!ossl_prov_is_running())
 775         return NULL;
 776
 777     drbg = OPENSSL_zalloc(sizeof(*drbg));
 778     if (drbg == NULL)
 779         return NULL;
 780
 781     drbg->provctx = provctx;
 782     drbg->instantiate = instantiate;
 783     drbg->uninstantiate = uninstantiate;
 784     drbg->reseed = reseed;
 785     drbg->generate = generate;
 786     drbg->fork_id = openssl_get_fork_id();
 787
 788     /* Extract parent's functions */
 789     drbg->parent = parent;
 790     if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_ENABLE_LOCKING)) != NULL)
 791         drbg->parent_enable_locking = OSSL_FUNC_rand_enable_locking(pfunc);
 792     if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_LOCK)) != NULL)
 793         drbg->parent_lock = OSSL_FUNC_rand_lock(pfunc);
 794     if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_UNLOCK)) != NULL)
 795         drbg->parent_unlock = OSSL_FUNC_rand_unlock(pfunc);
 796     if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_GET_CTX_PARAMS)) != NULL)
 797         drbg->parent_get_ctx_params = OSSL_FUNC_rand_get_ctx_params(pfunc);
 798     if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_NONCE)) != NULL)
 799         drbg->parent_nonce = OSSL_FUNC_rand_nonce(pfunc);
 800     if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_GET_SEED)) != NULL)
 801         drbg->parent_get_seed = OSSL_FUNC_rand_get_seed(pfunc);
 802     if ((pfunc = find_call(p_dispatch, OSSL_FUNC_RAND_CLEAR_SEED)) != NULL)
 803         drbg->parent_clear_seed = OSSL_FUNC_rand_clear_seed(pfunc);
 804
 805     /* Set some default maximums up */
 806     drbg->max_entropylen = DRBG_MAX_LENGTH;
 807     drbg->max_noncelen = DRBG_MAX_LENGTH;
 808     drbg->max_perslen = DRBG_MAX_LENGTH;
 809     drbg->max_adinlen = DRBG_MAX_LENGTH;
 810     drbg->generate_counter = 1;
 811     drbg->reseed_counter = 1;
 812     drbg->reseed_interval = RESEED_INTERVAL;
 813     drbg->reseed_time_interval = TIME_INTERVAL;
 814
 815     if (!dnew(drbg))
 816         goto err;
 817
 818     if (parent != NULL) {
 819         if (!get_parent_strength(drbg, &p_str))
 820             goto err;
 821         if (drbg->strength > p_str) {
 822             /*
 823              * We currently don't support the algorithm from NIST SP 800-90C
 824              * 10.1.2 to use a weaker DRBG as source
 825              */
 826             ERR_raise(ERR_LIB_PROV, PROV_R_PARENT_STRENGTH_TOO_WEAK);
 827             goto err;
 828         }
 829     }
 830 #ifdef TSAN_REQUIRES_LOCKING
 831     if (!ossl_drbg_enable_locking(drbg))
 832         goto err;
 833 #endif
 834     return drbg;
 835
 836  err:
 837     ossl_rand_drbg_free(drbg);
 838     return NULL;
 839 }
 840
 841 void ossl_rand_drbg_free(PROV_DRBG *drbg)
 842 {
 843     if (drbg == NULL)
 844         return;
 845
 846     CRYPTO_THREAD_lock_free(drbg->lock);
 847     OPENSSL_free(drbg);
 848 }
 849
 850 int ossl_drbg_get_ctx_params(PROV_DRBG *drbg, OSSL_PARAM params[])
 851 {
 852     OSSL_PARAM *p;
 853
 854     p = OSSL_PARAM_locate(params, OSSL_RAND_PARAM_STATE);
 855     if (p != NULL && !OSSL_PARAM_set_int(p, drbg->state))
 856         return 0;
 857
 858     p = OSSL_PARAM_locate(params, OSSL_RAND_PARAM_STRENGTH);
 859     if (p != NULL && !OSSL_PARAM_set_int(p, drbg->strength))
 860         return 0;
 861
 862     p = OSSL_PARAM_locate(params, OSSL_RAND_PARAM_MAX_REQUEST);
 863     if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->max_request))
 864         return 0;
 865
 866     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MIN_ENTROPYLEN);
 867     if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->min_entropylen))
 868         return 0;
 869
 870     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MAX_ENTROPYLEN);
 871     if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->max_entropylen))
 872         return 0;
 873
 874     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MIN_NONCELEN);
 875     if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->min_noncelen))
 876         return 0;
 877
 878     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MAX_NONCELEN);
 879     if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->max_noncelen))
 880         return 0;
 881
 882     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MAX_PERSLEN);
 883     if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->max_perslen))
 884         return 0;
 885
 886     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_MAX_ADINLEN);
 887     if (p != NULL && !OSSL_PARAM_set_size_t(p, drbg->max_adinlen))
 888         return 0;
 889
 890     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_RESEED_REQUESTS);
 891     if (p != NULL && !OSSL_PARAM_set_uint(p, drbg->reseed_interval))
 892         return 0;
 893
 894     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_RESEED_TIME);
 895     if (p != NULL && !OSSL_PARAM_set_time_t(p, drbg->reseed_time))
 896         return 0;
 897
 898     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL);
 899     if (p != NULL && !OSSL_PARAM_set_time_t(p, drbg->reseed_time_interval))
 900         return 0;
 901
 902     p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_RESEED_COUNTER);
 903     if (p != NULL
 904             && !OSSL_PARAM_set_uint(p, tsan_load(&drbg->reseed_counter)))
 905         return 0;
 906     return 1;
 907 }
 908
 909 int ossl_drbg_set_ctx_params(PROV_DRBG *drbg, const OSSL_PARAM params[])
 910 {
 911     const OSSL_PARAM *p;
 912
 913     if (params == NULL)
 914         return 1;
 915
 916     p = OSSL_PARAM_locate_const(params, OSSL_DRBG_PARAM_RESEED_REQUESTS);
 917     if (p != NULL && !OSSL_PARAM_get_uint(p, &drbg->reseed_interval))
 918         return 0;
 919
 920     p = OSSL_PARAM_locate_const(params, OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL);
 921     if (p != NULL && !OSSL_PARAM_get_time_t(p, &drbg->reseed_time_interval))
 922         return 0;
 923     return 1;
 924 }