crypto/evp/digest.c

   1 /*
   2  * Copyright 1995-2019 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 <stdio.h>
  11 #include <openssl/objects.h>
  12 #include <openssl/evp.h>
  13 #include <openssl/engine.h>
  14 #include <openssl/params.h>
  15 #include <openssl/core_names.h>
  16 #include "internal/cryptlib.h"
  17 #include "internal/evp_int.h"
  18 #include "internal/provider.h"
  19 #include "evp_locl.h"
  20
  21 /* This call frees resources associated with the context */
  22 int EVP_MD_CTX_reset(EVP_MD_CTX *ctx)
  23 {
  24     if (ctx == NULL)
  25         return 1;
  26
  27     if (ctx->digest == NULL || ctx->digest->prov == NULL)
  28         goto legacy;
  29
  30     if (ctx->provctx != NULL) {
  31         if (ctx->digest->freectx != NULL)
  32             ctx->digest->freectx(ctx->provctx);
  33         ctx->provctx = NULL;
  34         EVP_MD_CTX_set_flags(ctx, EVP_MD_CTX_FLAG_CLEANED);
  35     }
  36
  37     if (ctx->pctx != NULL)
  38         goto legacy;
  39
  40     return 1;
  41
  42     /* TODO(3.0): Remove legacy code below */
  43  legacy:
  44
  45     /*
  46      * Don't assume ctx->md_data was cleaned in EVP_Digest_Final, because
  47      * sometimes only copies of the context are ever finalised.
  48      */
  49     if (ctx->digest && ctx->digest->cleanup
  50         && !EVP_MD_CTX_test_flags(ctx, EVP_MD_CTX_FLAG_CLEANED))
  51         ctx->digest->cleanup(ctx);
  52     if (ctx->digest && ctx->digest->ctx_size && ctx->md_data
  53         && !EVP_MD_CTX_test_flags(ctx, EVP_MD_CTX_FLAG_REUSE)) {
  54         OPENSSL_clear_free(ctx->md_data, ctx->digest->ctx_size);
  55     }
  56     /*
  57      * pctx should be freed by the user of EVP_MD_CTX
  58      * if EVP_MD_CTX_FLAG_KEEP_PKEY_CTX is set
  59      */
  60 #ifndef FIPS_MODE
  61     /* TODO(3.0): Temporarily no support for EVP_DigestSign* in FIPS module */
  62     if (!EVP_MD_CTX_test_flags(ctx, EVP_MD_CTX_FLAG_KEEP_PKEY_CTX))
  63         EVP_PKEY_CTX_free(ctx->pctx);
  64
  65 # ifndef OPENSSL_NO_ENGINE
  66     ENGINE_finish(ctx->engine);
  67 # endif
  68 #endif
  69     OPENSSL_cleanse(ctx, sizeof(*ctx));
  70
  71     return 1;
  72 }
  73
  74 EVP_MD_CTX *EVP_MD_CTX_new(void)
  75 {
  76     return OPENSSL_zalloc(sizeof(EVP_MD_CTX));
  77 }
  78
  79 void EVP_MD_CTX_free(EVP_MD_CTX *ctx)
  80 {
  81     if (ctx == NULL)
  82         return;
  83
  84     if (ctx->digest == NULL || ctx->digest->prov == NULL)
  85         goto legacy;
  86
  87     EVP_MD_CTX_reset(ctx);
  88
  89     EVP_MD_meth_free(ctx->fetched_digest);
  90     ctx->fetched_digest = NULL;
  91     ctx->digest = NULL;
  92     ctx->reqdigest = NULL;
  93
  94     OPENSSL_free(ctx);
  95     return;
  96
  97     /* TODO(3.0): Remove legacy code below */
  98  legacy:
  99     EVP_MD_CTX_reset(ctx);
 100     OPENSSL_free(ctx);
 101 }
 102
 103 int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type)
 104 {
 105     EVP_MD_CTX_reset(ctx);
 106     return EVP_DigestInit_ex(ctx, type, NULL);
 107 }
 108
 109 int EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl)
 110 {
 111 #if !defined(OPENSSL_NO_ENGINE) && !defined(FIPS_MODE)
 112     ENGINE *tmpimpl = NULL;
 113 #endif
 114
 115     EVP_MD_CTX_clear_flags(ctx, EVP_MD_CTX_FLAG_CLEANED);
 116
 117     if (type != NULL)
 118         ctx->reqdigest = type;
 119
 120     /* TODO(3.0): Legacy work around code below. Remove this */
 121 #if !defined(OPENSSL_NO_ENGINE) && !defined(FIPS_MODE)
 122     /*
 123      * Whether it's nice or not, "Inits" can be used on "Final"'d contexts so
 124      * this context may already have an ENGINE! Try to avoid releasing the
 125      * previous handle, re-querying for an ENGINE, and having a
 126      * reinitialisation, when it may all be unnecessary.
 127      */
 128     if (ctx->engine && ctx->digest &&
 129         (type == NULL || (type->type == ctx->digest->type)))
 130         goto skip_to_init;
 131
 132     if (type != NULL) {
 133         /*
 134          * Ensure an ENGINE left lying around from last time is cleared (the
 135          * previous check attempted to avoid this if the same ENGINE and
 136          * EVP_MD could be used).
 137          */
 138         ENGINE_finish(ctx->engine);
 139         ctx->engine = NULL;
 140     }
 141
 142     if (type != NULL && impl == NULL)
 143         tmpimpl = ENGINE_get_digest_engine(type->type);
 144 #endif
 145
 146     /*
 147      * If there are engines involved or if we're being used as part of
 148      * EVP_DigestSignInit then we should use legacy handling for now.
 149      */
 150     if (ctx->engine != NULL
 151             || impl != NULL
 152 #if !defined(OPENSSL_NO_ENGINE) && !defined(FIPS_MODE)
 153             || tmpimpl != NULL
 154 #endif
 155             || ctx->pctx != NULL
 156             || (ctx->flags & EVP_MD_CTX_FLAG_NO_INIT) != 0) {
 157         if (ctx->digest == ctx->fetched_digest)
 158             ctx->digest = NULL;
 159         EVP_MD_meth_free(ctx->fetched_digest);
 160         ctx->fetched_digest = NULL;
 161         goto legacy;
 162     }
 163
 164     if (ctx->digest != NULL && ctx->digest->ctx_size > 0) {
 165         OPENSSL_clear_free(ctx->md_data, ctx->digest->ctx_size);
 166         ctx->md_data = NULL;
 167     }
 168
 169     /* TODO(3.0): Start of non-legacy code below */
 170
 171     if (type->prov == NULL) {
 172 #ifdef FIPS_MODE
 173         /* We only do explict fetches inside the FIPS module */
 174         EVPerr(EVP_F_EVP_DIGESTINIT_EX, EVP_R_INITIALIZATION_ERROR);
 175         return 0;
 176 #else
 177         EVP_MD *provmd = EVP_MD_fetch(NULL, OBJ_nid2sn(type->type), "");
 178
 179         if (provmd == NULL) {
 180             EVPerr(EVP_F_EVP_DIGESTINIT_EX, EVP_R_INITIALIZATION_ERROR);
 181             return 0;
 182         }
 183         type = provmd;
 184         EVP_MD_meth_free(ctx->fetched_digest);
 185         ctx->fetched_digest = provmd;
 186 #endif
 187     }
 188
 189     if (ctx->provctx != NULL && ctx->digest != NULL && ctx->digest != type) {
 190         if (ctx->digest->freectx != NULL)
 191             ctx->digest->freectx(ctx->provctx);
 192         ctx->provctx = NULL;
 193     }
 194     ctx->digest = type;
 195     if (ctx->provctx == NULL) {
 196         ctx->provctx = ctx->digest->newctx(ossl_provider_ctx(type->prov));
 197         if (ctx->provctx == NULL) {
 198             EVPerr(EVP_F_EVP_DIGESTINIT_EX, EVP_R_INITIALIZATION_ERROR);
 199             return 0;
 200         }
 201     }
 202
 203     if (ctx->digest->dinit == NULL) {
 204         EVPerr(EVP_F_EVP_DIGESTINIT_EX, EVP_R_INITIALIZATION_ERROR);
 205         return 0;
 206     }
 207
 208     return ctx->digest->dinit(ctx->provctx);
 209
 210     /* TODO(3.0): Remove legacy code below */
 211  legacy:
 212
 213 #if !defined(OPENSSL_NO_ENGINE) && !defined(FIPS_MODE)
 214     if (type) {
 215         if (impl != NULL) {
 216             if (!ENGINE_init(impl)) {
 217                 EVPerr(EVP_F_EVP_DIGESTINIT_EX, EVP_R_INITIALIZATION_ERROR);
 218                 return 0;
 219             }
 220         } else {
 221             /* Ask if an ENGINE is reserved for this job */
 222             impl = tmpimpl;
 223         }
 224         if (impl != NULL) {
 225             /* There's an ENGINE for this job ... (apparently) */
 226             const EVP_MD *d = ENGINE_get_digest(impl, type->type);
 227
 228             if (d == NULL) {
 229                 EVPerr(EVP_F_EVP_DIGESTINIT_EX, EVP_R_INITIALIZATION_ERROR);
 230                 ENGINE_finish(impl);
 231                 return 0;
 232             }
 233             /* We'll use the ENGINE's private digest definition */
 234             type = d;
 235             /*
 236              * Store the ENGINE functional reference so we know 'type' came
 237              * from an ENGINE and we need to release it when done.
 238              */
 239             ctx->engine = impl;
 240         } else
 241             ctx->engine = NULL;
 242     } else {
 243         if (!ctx->digest) {
 244             EVPerr(EVP_F_EVP_DIGESTINIT_EX, EVP_R_NO_DIGEST_SET);
 245             return 0;
 246         }
 247         type = ctx->digest;
 248     }
 249 #endif
 250     if (ctx->digest != type) {
 251         if (ctx->digest && ctx->digest->ctx_size) {
 252             OPENSSL_clear_free(ctx->md_data, ctx->digest->ctx_size);
 253             ctx->md_data = NULL;
 254         }
 255         ctx->digest = type;
 256         if (!(ctx->flags & EVP_MD_CTX_FLAG_NO_INIT) && type->ctx_size) {
 257             ctx->update = type->update;
 258             ctx->md_data = OPENSSL_zalloc(type->ctx_size);
 259             if (ctx->md_data == NULL) {
 260                 EVPerr(EVP_F_EVP_DIGESTINIT_EX, ERR_R_MALLOC_FAILURE);
 261                 return 0;
 262             }
 263         }
 264     }
 265 #if !defined(OPENSSL_NO_ENGINE) && !defined(FIPS_MODE)
 266  skip_to_init:
 267 #endif
 268 #ifndef FIPS_MODE
 269     /* TODO(3.0): Temporarily no support for EVP_DigestSign* in FIPS module */
 270     if (ctx->pctx != NULL) {
 271         int r;
 272         r = EVP_PKEY_CTX_ctrl(ctx->pctx, -1, EVP_PKEY_OP_TYPE_SIG,
 273                               EVP_PKEY_CTRL_DIGESTINIT, 0, ctx);
 274         if (r <= 0 && (r != -2))
 275             return 0;
 276     }
 277 #endif
 278     if (ctx->flags & EVP_MD_CTX_FLAG_NO_INIT)
 279         return 1;
 280     return ctx->digest->init(ctx);
 281 }
 282
 283 int EVP_DigestUpdate(EVP_MD_CTX *ctx, const void *data, size_t count)
 284 {
 285     if (count == 0)
 286         return 1;
 287
 288     if (ctx->digest == NULL || ctx->digest->prov == NULL)
 289         goto legacy;
 290
 291     if (ctx->digest->dupdate == NULL) {
 292         EVPerr(EVP_F_EVP_DIGESTUPDATE, EVP_R_UPDATE_ERROR);
 293         return 0;
 294     }
 295     return ctx->digest->dupdate(ctx->provctx, data, count);
 296
 297     /* TODO(3.0): Remove legacy code below */
 298  legacy:
 299     return ctx->update(ctx, data, count);
 300 }
 301
 302 /* The caller can assume that this removes any secret data from the context */
 303 int EVP_DigestFinal(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *size)
 304 {
 305     int ret;
 306     ret = EVP_DigestFinal_ex(ctx, md, size);
 307     EVP_MD_CTX_reset(ctx);
 308     return ret;
 309 }
 310
 311 /* The caller can assume that this removes any secret data from the context */
 312 int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *isize)
 313 {
 314     int ret;
 315     size_t size = 0;
 316     size_t mdsize = EVP_MD_size(ctx->digest);
 317
 318     if (ctx->digest == NULL || ctx->digest->prov == NULL)
 319         goto legacy;
 320
 321     if (ctx->digest->dfinal == NULL) {
 322         EVPerr(EVP_F_EVP_DIGESTFINAL_EX, EVP_R_FINAL_ERROR);
 323         return 0;
 324     }
 325
 326     ret = ctx->digest->dfinal(ctx->provctx, md, &size, mdsize);
 327
 328     if (isize != NULL) {
 329         if (size <= UINT_MAX) {
 330             *isize = (int)size;
 331         } else {
 332             EVPerr(EVP_F_EVP_DIGESTFINAL_EX, EVP_R_FINAL_ERROR);
 333             ret = 0;
 334         }
 335     }
 336
 337     EVP_MD_CTX_reset(ctx);
 338     return ret;
 339
 340     /* TODO(3.0): Remove legacy code below */
 341  legacy:
 342     OPENSSL_assert(mdsize <= EVP_MAX_MD_SIZE);
 343     ret = ctx->digest->final(ctx, md);
 344     if (isize != NULL)
 345         *isize = mdsize;
 346     if (ctx->digest->cleanup) {
 347         ctx->digest->cleanup(ctx);
 348         EVP_MD_CTX_set_flags(ctx, EVP_MD_CTX_FLAG_CLEANED);
 349     }
 350     OPENSSL_cleanse(ctx->md_data, ctx->digest->ctx_size);
 351     return ret;
 352 }
 353
 354 int EVP_DigestFinalXOF(EVP_MD_CTX *ctx, unsigned char *md, size_t size)
 355 {
 356     int ret = 0;
 357     OSSL_PARAM params[2];
 358     size_t i = 0;
 359
 360     if (ctx->digest == NULL || ctx->digest->prov == NULL)
 361         goto legacy;
 362
 363     if (ctx->digest->dfinal == NULL) {
 364         EVPerr(EVP_F_EVP_DIGESTFINALXOF, EVP_R_FINAL_ERROR);
 365         return 0;
 366     }
 367
 368     params[i++] = OSSL_PARAM_construct_size_t(OSSL_DIGEST_PARAM_XOFLEN, &size);
 369     params[i++] = OSSL_PARAM_construct_end();
 370
 371     if (EVP_MD_CTX_set_params(ctx, params) > 0)
 372         ret = ctx->digest->dfinal(ctx->provctx, md, &size, size);
 373     EVP_MD_CTX_reset(ctx);
 374     return ret;
 375
 376 legacy:
 377     if (ctx->digest->flags & EVP_MD_FLAG_XOF
 378         && size <= INT_MAX
 379         && ctx->digest->md_ctrl(ctx, EVP_MD_CTRL_XOF_LEN, (int)size, NULL)) {
 380         ret = ctx->digest->final(ctx, md);
 381         if (ctx->digest->cleanup != NULL) {
 382             ctx->digest->cleanup(ctx);
 383             EVP_MD_CTX_set_flags(ctx, EVP_MD_CTX_FLAG_CLEANED);
 384         }
 385         OPENSSL_cleanse(ctx->md_data, ctx->digest->ctx_size);
 386     } else {
 387         EVPerr(EVP_F_EVP_DIGESTFINALXOF, EVP_R_NOT_XOF_OR_INVALID_LENGTH);
 388     }
 389
 390     return ret;
 391 }
 392
 393 int EVP_MD_CTX_copy(EVP_MD_CTX *out, const EVP_MD_CTX *in)
 394 {
 395     EVP_MD_CTX_reset(out);
 396     return EVP_MD_CTX_copy_ex(out, in);
 397 }
 398
 399 int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out, const EVP_MD_CTX *in)
 400 {
 401     unsigned char *tmp_buf;
 402
 403     if (in == NULL || in->digest == NULL) {
 404         EVPerr(EVP_F_EVP_MD_CTX_COPY_EX, EVP_R_INPUT_NOT_INITIALIZED);
 405         return 0;
 406     }
 407
 408     if (in->digest->prov == NULL)
 409         goto legacy;
 410
 411     if (in->digest->dupctx == NULL) {
 412         EVPerr(EVP_F_EVP_MD_CTX_COPY_EX, EVP_R_NOT_ABLE_TO_COPY_CTX);
 413         return 0;
 414     }
 415
 416     EVP_MD_CTX_reset(out);
 417     if (out->fetched_digest != NULL)
 418         EVP_MD_meth_free(out->fetched_digest);
 419     *out = *in;
 420     /* NULL out pointers in case of error */
 421     out->pctx = NULL;
 422     out->provctx = NULL;
 423
 424     if (in->fetched_digest != NULL)
 425         EVP_MD_upref(in->fetched_digest);
 426
 427     out->provctx = in->digest->dupctx(in->provctx);
 428     if (out->provctx == NULL) {
 429         EVPerr(EVP_F_EVP_MD_CTX_COPY_EX, EVP_R_NOT_ABLE_TO_COPY_CTX);
 430         return 0;
 431     }
 432
 433     /* copied EVP_MD_CTX should free the copied EVP_PKEY_CTX */
 434     EVP_MD_CTX_clear_flags(out, EVP_MD_CTX_FLAG_KEEP_PKEY_CTX);
 435 #ifndef FIPS_MODE
 436     /* TODO(3.0): Temporarily no support for EVP_DigestSign* in FIPS module */
 437     if (in->pctx != NULL) {
 438         out->pctx = EVP_PKEY_CTX_dup(in->pctx);
 439         if (out->pctx == NULL) {
 440             EVPerr(EVP_F_EVP_MD_CTX_COPY_EX, EVP_R_NOT_ABLE_TO_COPY_CTX);
 441             EVP_MD_CTX_reset(out);
 442             return 0;
 443         }
 444     }
 445 #endif
 446
 447     return 1;
 448
 449     /* TODO(3.0): Remove legacy code below */
 450  legacy:
 451 #if !defined(OPENSSL_NO_ENGINE) && !defined(FIPS_MODE)
 452     /* Make sure it's safe to copy a digest context using an ENGINE */
 453     if (in->engine && !ENGINE_init(in->engine)) {
 454         EVPerr(EVP_F_EVP_MD_CTX_COPY_EX, ERR_R_ENGINE_LIB);
 455         return 0;
 456     }
 457 #endif
 458
 459     if (out->digest == in->digest) {
 460         tmp_buf = out->md_data;
 461         EVP_MD_CTX_set_flags(out, EVP_MD_CTX_FLAG_REUSE);
 462     } else
 463         tmp_buf = NULL;
 464     EVP_MD_CTX_reset(out);
 465     memcpy(out, in, sizeof(*out));
 466
 467     /* copied EVP_MD_CTX should free the copied EVP_PKEY_CTX */
 468     EVP_MD_CTX_clear_flags(out, EVP_MD_CTX_FLAG_KEEP_PKEY_CTX);
 469
 470     /* Null these variables, since they are getting fixed up
 471      * properly below.  Anything else may cause a memleak and/or
 472      * double free if any of the memory allocations below fail
 473      */
 474     out->md_data = NULL;
 475     out->pctx = NULL;
 476
 477     if (in->md_data && out->digest->ctx_size) {
 478         if (tmp_buf)
 479             out->md_data = tmp_buf;
 480         else {
 481             out->md_data = OPENSSL_malloc(out->digest->ctx_size);
 482             if (out->md_data == NULL) {
 483                 EVPerr(EVP_F_EVP_MD_CTX_COPY_EX, ERR_R_MALLOC_FAILURE);
 484                 return 0;
 485             }
 486         }
 487         memcpy(out->md_data, in->md_data, out->digest->ctx_size);
 488     }
 489
 490     out->update = in->update;
 491
 492 #ifndef FIPS_MODE
 493     /* TODO(3.0): Temporarily no support for EVP_DigestSign* in FIPS module */
 494     if (in->pctx) {
 495         out->pctx = EVP_PKEY_CTX_dup(in->pctx);
 496         if (!out->pctx) {
 497             EVP_MD_CTX_reset(out);
 498             return 0;
 499         }
 500     }
 501 #endif
 502
 503     if (out->digest->copy)
 504         return out->digest->copy(out, in);
 505
 506     return 1;
 507 }
 508
 509 int EVP_Digest(const void *data, size_t count,
 510                unsigned char *md, unsigned int *size, const EVP_MD *type,
 511                ENGINE *impl)
 512 {
 513     EVP_MD_CTX *ctx = EVP_MD_CTX_new();
 514     int ret;
 515
 516     if (ctx == NULL)
 517         return 0;
 518     EVP_MD_CTX_set_flags(ctx, EVP_MD_CTX_FLAG_ONESHOT);
 519     ret = EVP_DigestInit_ex(ctx, type, impl)
 520         && EVP_DigestUpdate(ctx, data, count)
 521         && EVP_DigestFinal_ex(ctx, md, size);
 522     EVP_MD_CTX_free(ctx);
 523
 524     return ret;
 525 }
 526
 527 int EVP_MD_CTX_set_params(EVP_MD_CTX *ctx, const OSSL_PARAM params[])
 528 {
 529     if (ctx->digest != NULL && ctx->digest->set_params != NULL)
 530         return ctx->digest->set_params(ctx->provctx, params);
 531     return 0;
 532 }
 533
 534 int EVP_MD_CTX_get_params(EVP_MD_CTX *ctx, OSSL_PARAM params[])
 535 {
 536     if (ctx->digest != NULL && ctx->digest->get_params != NULL)
 537         return ctx->digest->get_params(ctx->provctx, params);
 538     return 0;
 539 }
 540
 541 /* TODO(3.0): Remove legacy code below - only used by engines & DigestSign */
 542 int EVP_MD_CTX_ctrl(EVP_MD_CTX *ctx, int cmd, int p1, void *p2)
 543 {
 544     if (ctx->digest != NULL) {
 545         if (ctx->digest->prov != NULL) {
 546             OSSL_PARAM params[2];
 547             size_t i, n = 0;
 548
 549             switch (cmd) {
 550             case EVP_MD_CTRL_XOF_LEN:
 551                 if (ctx->digest->set_params == NULL)
 552                     break;
 553                 i = (size_t)p1;
 554                 params[n++] =
 555                     OSSL_PARAM_construct_size_t(OSSL_DIGEST_PARAM_XOFLEN, &i);
 556                 params[n++] = OSSL_PARAM_construct_end();
 557                 return ctx->digest->set_params(ctx->provctx, params);
 558             case EVP_MD_CTRL_MICALG:
 559                 if (ctx->digest->get_params == NULL)
 560                     break;
 561                 params[n++] =
 562                     OSSL_PARAM_construct_utf8_string(OSSL_DIGEST_PARAM_MICALG,
 563                                                      p2, p1 ? p1 : 9999);
 564                 params[n++] = OSSL_PARAM_construct_end();
 565                 return ctx->digest->get_params(ctx->provctx, params);
 566             }
 567             return 0;
 568         }
 569         /* legacy code */
 570         if (ctx->digest->md_ctrl != NULL) {
 571             int ret = ctx->digest->md_ctrl(ctx, cmd, p1, p2);
 572             if (ret <= 0)
 573                 return 0;
 574             return 1;
 575         }
 576     }
 577     return 0;
 578 }
 579
 580 static void *evp_md_from_dispatch(const OSSL_DISPATCH *fns,
 581                                   OSSL_PROVIDER *prov)
 582 {
 583     EVP_MD *md = NULL;
 584     int fncnt = 0;
 585
 586     /* EVP_MD_fetch() will set the legacy NID if available */
 587     if ((md = EVP_MD_meth_new(NID_undef, NID_undef)) == NULL)
 588         return NULL;
 589
 590     for (; fns->function_id != 0; fns++) {
 591         switch (fns->function_id) {
 592         case OSSL_FUNC_DIGEST_NEWCTX:
 593             if (md->newctx == NULL) {
 594                 md->newctx = OSSL_get_OP_digest_newctx(fns);
 595                 fncnt++;
 596             }
 597             break;
 598         case OSSL_FUNC_DIGEST_INIT:
 599             if (md->dinit == NULL) {
 600                 md->dinit = OSSL_get_OP_digest_init(fns);
 601                 fncnt++;
 602             }
 603             break;
 604         case OSSL_FUNC_DIGEST_UPDATE:
 605             if (md->dupdate == NULL) {
 606                 md->dupdate = OSSL_get_OP_digest_update(fns);
 607                 fncnt++;
 608             }
 609             break;
 610         case OSSL_FUNC_DIGEST_FINAL:
 611             if (md->dfinal == NULL) {
 612                 md->dfinal = OSSL_get_OP_digest_final(fns);
 613                 fncnt++;
 614             }
 615             break;
 616         case OSSL_FUNC_DIGEST_DIGEST:
 617             if (md->digest == NULL)
 618                 md->digest = OSSL_get_OP_digest_digest(fns);
 619             /* We don't increment fnct for this as it is stand alone */
 620             break;
 621         case OSSL_FUNC_DIGEST_FREECTX:
 622             if (md->freectx == NULL) {
 623                 md->freectx = OSSL_get_OP_digest_freectx(fns);
 624                 fncnt++;
 625             }
 626             break;
 627         case OSSL_FUNC_DIGEST_DUPCTX:
 628             if (md->dupctx == NULL)
 629                 md->dupctx = OSSL_get_OP_digest_dupctx(fns);
 630             break;
 631         case OSSL_FUNC_DIGEST_SIZE:
 632             if (md->size == NULL)
 633                 md->size = OSSL_get_OP_digest_size(fns);
 634             break;
 635         case OSSL_FUNC_DIGEST_BLOCK_SIZE:
 636             if (md->dblock_size == NULL)
 637                 md->dblock_size = OSSL_get_OP_digest_block_size(fns);
 638             break;
 639         case OSSL_FUNC_DIGEST_SET_PARAMS:
 640             if (md->set_params == NULL)
 641                 md->set_params = OSSL_get_OP_digest_set_params(fns);
 642             break;
 643         case OSSL_FUNC_DIGEST_GET_PARAMS:
 644             if (md->get_params == NULL)
 645                 md->get_params = OSSL_get_OP_digest_get_params(fns);
 646             break;
 647         }
 648     }
 649     if ((fncnt != 0 && fncnt != 5)
 650         || (fncnt == 0 && md->digest == NULL)
 651         || md->size == NULL) {
 652         /*
 653          * In order to be a consistent set of functions we either need the
 654          * whole set of init/update/final etc functions or none of them.
 655          * The "digest" function can standalone. We at least need one way to
 656          * generate digests.
 657          */
 658         EVP_MD_meth_free(md);
 659         return NULL;
 660     }
 661     md->prov = prov;
 662     if (prov != NULL)
 663         ossl_provider_upref(prov);
 664
 665     return md;
 666 }
 667
 668 static int evp_md_upref(void *md)
 669 {
 670     return EVP_MD_upref(md);
 671 }
 672
 673 static void evp_md_free(void *md)
 674 {
 675     EVP_MD_meth_free(md);
 676 }
 677
 678 EVP_MD *EVP_MD_fetch(OPENSSL_CTX *ctx, const char *algorithm,
 679                      const char *properties)
 680 {
 681     EVP_MD *md =
 682         evp_generic_fetch(ctx, OSSL_OP_DIGEST, algorithm, properties,
 683                           evp_md_from_dispatch, evp_md_upref,
 684                           evp_md_free);
 685
 686 #ifndef FIPS_MODE
 687     /* TODO(3.x) get rid of the need for legacy NIDs */
 688     if (md != NULL) {
 689         /*
 690          * FIPS module note: since internal fetches will be entirely
 691          * provider based, we know that none of its code depends on legacy
 692          * NIDs or any functionality that use them.
 693          */
 694         md->type = OBJ_sn2nid(algorithm);
 695     }
 696 #endif
 697
 698     return md;
 699 }