crypto/rsa/rsa_ossl.c

   1 /*
   2  * Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include "internal/cryptlib.h"
  11 #include "internal/bn_int.h"
  12 #include "rsa_locl.h"
  13
  14 static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
  15                                   unsigned char *to, RSA *rsa, int padding);
  16 static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
  17                                    unsigned char *to, RSA *rsa, int padding);
  18 static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
  19                                   unsigned char *to, RSA *rsa, int padding);
  20 static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
  21                                    unsigned char *to, RSA *rsa, int padding);
  22 static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
  23                            BN_CTX *ctx);
  24 static int rsa_ossl_init(RSA *rsa);
  25 static int rsa_ossl_finish(RSA *rsa);
  26 static RSA_METHOD rsa_pkcs1_ossl_meth = {
  27     "OpenSSL PKCS#1 RSA",
  28     rsa_ossl_public_encrypt,
  29     rsa_ossl_public_decrypt,     /* signature verification */
  30     rsa_ossl_private_encrypt,    /* signing */
  31     rsa_ossl_private_decrypt,
  32     rsa_ossl_mod_exp,
  33     BN_mod_exp_mont,            /* XXX probably we should not use Montgomery
  34                                  * if e == 3 */
  35     rsa_ossl_init,
  36     rsa_ossl_finish,
  37     RSA_FLAG_FIPS_METHOD,       /* flags */
  38     NULL,
  39     0,                          /* rsa_sign */
  40     0,                          /* rsa_verify */
  41     NULL,                       /* rsa_keygen */
  42     NULL                        /* rsa_multi_prime_keygen */
  43 };
  44
  45 static const RSA_METHOD *default_RSA_meth = &rsa_pkcs1_ossl_meth;
  46
  47 void RSA_set_default_method(const RSA_METHOD *meth)
  48 {
  49     default_RSA_meth = meth;
  50 }
  51
  52 const RSA_METHOD *RSA_get_default_method(void)
  53 {
  54     return default_RSA_meth;
  55 }
  56
  57 const RSA_METHOD *RSA_PKCS1_OpenSSL(void)
  58 {
  59     return &rsa_pkcs1_ossl_meth;
  60 }
  61
  62 const RSA_METHOD *RSA_null_method(void)
  63 {
  64     return NULL;
  65 }
  66
  67 static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
  68                                   unsigned char *to, RSA *rsa, int padding)
  69 {
  70     BIGNUM *f, *ret;
  71     int i, j, k, num = 0, r = -1;
  72     unsigned char *buf = NULL;
  73     BN_CTX *ctx = NULL;
  74
  75     if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
  76         RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_MODULUS_TOO_LARGE);
  77         return -1;
  78     }
  79
  80     if (BN_ucmp(rsa->n, rsa->e) <= 0) {
  81         RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
  82         return -1;
  83     }
  84
  85     /* for large moduli, enforce exponent limit */
  86     if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
  87         if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
  88             RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
  89             return -1;
  90         }
  91     }
  92
  93     if ((ctx = BN_CTX_new()) == NULL)
  94         goto err;
  95     BN_CTX_start(ctx);
  96     f = BN_CTX_get(ctx);
  97     ret = BN_CTX_get(ctx);
  98     num = BN_num_bytes(rsa->n);
  99     buf = OPENSSL_malloc(num);
 100     if (ret == NULL || buf == NULL) {
 101         RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, ERR_R_MALLOC_FAILURE);
 102         goto err;
 103     }
 104
 105     switch (padding) {
 106     case RSA_PKCS1_PADDING:
 107         i = RSA_padding_add_PKCS1_type_2(buf, num, from, flen);
 108         break;
 109     case RSA_PKCS1_OAEP_PADDING:
 110         i = RSA_padding_add_PKCS1_OAEP(buf, num, from, flen, NULL, 0);
 111         break;
 112     case RSA_SSLV23_PADDING:
 113         i = RSA_padding_add_SSLv23(buf, num, from, flen);
 114         break;
 115     case RSA_NO_PADDING:
 116         i = RSA_padding_add_none(buf, num, from, flen);
 117         break;
 118     default:
 119         RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
 120         goto err;
 121     }
 122     if (i <= 0)
 123         goto err;
 124
 125     if (BN_bin2bn(buf, num, f) == NULL)
 126         goto err;
 127
 128     if (BN_ucmp(f, rsa->n) >= 0) {
 129         /* usually the padding functions would catch this */
 130         RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT,
 131                RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
 132         goto err;
 133     }
 134
 135     if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
 136         if (!BN_MONT_CTX_set_locked
 137             (&rsa->_method_mod_n, rsa->lock, rsa->n, ctx))
 138             goto err;
 139
 140     if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
 141                                rsa->_method_mod_n))
 142         goto err;
 143
 144     /*
 145      * put in leading 0 bytes if the number is less than the length of the
 146      * modulus
 147      */
 148     j = BN_num_bytes(ret);
 149     i = BN_bn2bin(ret, &(to[num - j]));
 150     for (k = 0; k < (num - i); k++)
 151         to[k] = 0;
 152
 153     r = num;
 154  err:
 155     if (ctx != NULL)
 156         BN_CTX_end(ctx);
 157     BN_CTX_free(ctx);
 158     OPENSSL_clear_free(buf, num);
 159     return r;
 160 }
 161
 162 static BN_BLINDING *rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx)
 163 {
 164     BN_BLINDING *ret;
 165
 166     CRYPTO_THREAD_write_lock(rsa->lock);
 167
 168     if (rsa->blinding == NULL) {
 169         rsa->blinding = RSA_setup_blinding(rsa, ctx);
 170     }
 171
 172     ret = rsa->blinding;
 173     if (ret == NULL)
 174         goto err;
 175
 176     if (BN_BLINDING_is_current_thread(ret)) {
 177         /* rsa->blinding is ours! */
 178
 179         *local = 1;
 180     } else {
 181         /* resort to rsa->mt_blinding instead */
 182
 183         /*
 184          * instructs rsa_blinding_convert(), rsa_blinding_invert() that the
 185          * BN_BLINDING is shared, meaning that accesses require locks, and
 186          * that the blinding factor must be stored outside the BN_BLINDING
 187          */
 188         *local = 0;
 189
 190         if (rsa->mt_blinding == NULL) {
 191             rsa->mt_blinding = RSA_setup_blinding(rsa, ctx);
 192         }
 193         ret = rsa->mt_blinding;
 194     }
 195
 196  err:
 197     CRYPTO_THREAD_unlock(rsa->lock);
 198     return ret;
 199 }
 200
 201 static int rsa_blinding_convert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
 202                                 BN_CTX *ctx)
 203 {
 204     if (unblind == NULL) {
 205         /*
 206          * Local blinding: store the unblinding factor in BN_BLINDING.
 207          */
 208         return BN_BLINDING_convert_ex(f, NULL, b, ctx);
 209     } else {
 210         /*
 211          * Shared blinding: store the unblinding factor outside BN_BLINDING.
 212          */
 213         int ret;
 214
 215         BN_BLINDING_lock(b);
 216         ret = BN_BLINDING_convert_ex(f, unblind, b, ctx);
 217         BN_BLINDING_unlock(b);
 218
 219         return ret;
 220     }
 221 }
 222
 223 static int rsa_blinding_invert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
 224                                BN_CTX *ctx)
 225 {
 226     /*
 227      * For local blinding, unblind is set to NULL, and BN_BLINDING_invert_ex
 228      * will use the unblinding factor stored in BN_BLINDING. If BN_BLINDING
 229      * is shared between threads, unblind must be non-null:
 230      * BN_BLINDING_invert_ex will then use the local unblinding factor, and
 231      * will only read the modulus from BN_BLINDING. In both cases it's safe
 232      * to access the blinding without a lock.
 233      */
 234     return BN_BLINDING_invert_ex(f, unblind, b, ctx);
 235 }
 236
 237 /* signing */
 238 static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
 239                                    unsigned char *to, RSA *rsa, int padding)
 240 {
 241     BIGNUM *f, *ret, *res;
 242     int i, j, k, num = 0, r = -1;
 243     unsigned char *buf = NULL;
 244     BN_CTX *ctx = NULL;
 245     int local_blinding = 0;
 246     /*
 247      * Used only if the blinding structure is shared. A non-NULL unblind
 248      * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
 249      * the unblinding factor outside the blinding structure.
 250      */
 251     BIGNUM *unblind = NULL;
 252     BN_BLINDING *blinding = NULL;
 253
 254     if ((ctx = BN_CTX_new()) == NULL)
 255         goto err;
 256     BN_CTX_start(ctx);
 257     f = BN_CTX_get(ctx);
 258     ret = BN_CTX_get(ctx);
 259     num = BN_num_bytes(rsa->n);
 260     buf = OPENSSL_malloc(num);
 261     if (ret == NULL || buf == NULL) {
 262         RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
 263         goto err;
 264     }
 265
 266     switch (padding) {
 267     case RSA_PKCS1_PADDING:
 268         i = RSA_padding_add_PKCS1_type_1(buf, num, from, flen);
 269         break;
 270     case RSA_X931_PADDING:
 271         i = RSA_padding_add_X931(buf, num, from, flen);
 272         break;
 273     case RSA_NO_PADDING:
 274         i = RSA_padding_add_none(buf, num, from, flen);
 275         break;
 276     case RSA_SSLV23_PADDING:
 277     default:
 278         RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
 279         goto err;
 280     }
 281     if (i <= 0)
 282         goto err;
 283
 284     if (BN_bin2bn(buf, num, f) == NULL)
 285         goto err;
 286
 287     if (BN_ucmp(f, rsa->n) >= 0) {
 288         /* usually the padding functions would catch this */
 289         RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT,
 290                RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
 291         goto err;
 292     }
 293
 294     if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
 295         blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
 296         if (blinding == NULL) {
 297             RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_INTERNAL_ERROR);
 298             goto err;
 299         }
 300     }
 301
 302     if (blinding != NULL) {
 303         if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
 304             RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
 305             goto err;
 306         }
 307         if (!rsa_blinding_convert(blinding, f, unblind, ctx))
 308             goto err;
 309     }
 310
 311     if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
 312         (rsa->version == RSA_ASN1_VERSION_MULTI) ||
 313         ((rsa->p != NULL) &&
 314          (rsa->q != NULL) &&
 315          (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
 316         if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
 317             goto err;
 318     } else {
 319         BIGNUM *d = BN_new();
 320         if (d == NULL) {
 321             RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
 322             goto err;
 323         }
 324         BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
 325
 326         if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
 327             if (!BN_MONT_CTX_set_locked
 328                 (&rsa->_method_mod_n, rsa->lock, rsa->n, ctx)) {
 329                 BN_free(d);
 330                 goto err;
 331             }
 332
 333         if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
 334                                    rsa->_method_mod_n)) {
 335             BN_free(d);
 336             goto err;
 337         }
 338         /* We MUST free d before any further use of rsa->d */
 339         BN_free(d);
 340     }
 341
 342     if (blinding)
 343         if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
 344             goto err;
 345
 346     if (padding == RSA_X931_PADDING) {
 347         BN_sub(f, rsa->n, ret);
 348         if (BN_cmp(ret, f) > 0)
 349             res = f;
 350         else
 351             res = ret;
 352     } else {
 353         res = ret;
 354     }
 355
 356     /*
 357      * put in leading 0 bytes if the number is less than the length of the
 358      * modulus
 359      */
 360     j = BN_num_bytes(res);
 361     i = BN_bn2bin(res, &(to[num - j]));
 362     for (k = 0; k < (num - i); k++)
 363         to[k] = 0;
 364
 365     r = num;
 366  err:
 367     if (ctx != NULL)
 368         BN_CTX_end(ctx);
 369     BN_CTX_free(ctx);
 370     OPENSSL_clear_free(buf, num);
 371     return r;
 372 }
 373
 374 static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
 375                                    unsigned char *to, RSA *rsa, int padding)
 376 {
 377     BIGNUM *f, *ret;
 378     int j, num = 0, r = -1;
 379     unsigned char *p;
 380     unsigned char *buf = NULL;
 381     BN_CTX *ctx = NULL;
 382     int local_blinding = 0;
 383     /*
 384      * Used only if the blinding structure is shared. A non-NULL unblind
 385      * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
 386      * the unblinding factor outside the blinding structure.
 387      */
 388     BIGNUM *unblind = NULL;
 389     BN_BLINDING *blinding = NULL;
 390
 391     if ((ctx = BN_CTX_new()) == NULL)
 392         goto err;
 393     BN_CTX_start(ctx);
 394     f = BN_CTX_get(ctx);
 395     ret = BN_CTX_get(ctx);
 396     num = BN_num_bytes(rsa->n);
 397     buf = OPENSSL_malloc(num);
 398     if (ret == NULL || buf == NULL) {
 399         RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
 400         goto err;
 401     }
 402
 403     /*
 404      * This check was for equality but PGP does evil things and chops off the
 405      * top '0' bytes
 406      */
 407     if (flen > num) {
 408         RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT,
 409                RSA_R_DATA_GREATER_THAN_MOD_LEN);
 410         goto err;
 411     }
 412
 413     /* make data into a big number */
 414     if (BN_bin2bn(from, (int)flen, f) == NULL)
 415         goto err;
 416
 417     if (BN_ucmp(f, rsa->n) >= 0) {
 418         RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT,
 419                RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
 420         goto err;
 421     }
 422
 423     if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
 424         blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
 425         if (blinding == NULL) {
 426             RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_INTERNAL_ERROR);
 427             goto err;
 428         }
 429     }
 430
 431     if (blinding != NULL) {
 432         if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
 433             RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
 434             goto err;
 435         }
 436         if (!rsa_blinding_convert(blinding, f, unblind, ctx))
 437             goto err;
 438     }
 439
 440     /* do the decrypt */
 441     if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
 442         (rsa->version == RSA_ASN1_VERSION_MULTI) ||
 443         ((rsa->p != NULL) &&
 444          (rsa->q != NULL) &&
 445          (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
 446         if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
 447             goto err;
 448     } else {
 449         BIGNUM *d = BN_new();
 450         if (d == NULL) {
 451             RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
 452             goto err;
 453         }
 454         BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
 455
 456         if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
 457             if (!BN_MONT_CTX_set_locked
 458                 (&rsa->_method_mod_n, rsa->lock, rsa->n, ctx)) {
 459                 BN_free(d);
 460                 goto err;
 461             }
 462         if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
 463                                    rsa->_method_mod_n)) {
 464             BN_free(d);
 465             goto err;
 466         }
 467         /* We MUST free d before any further use of rsa->d */
 468         BN_free(d);
 469     }
 470
 471     if (blinding)
 472         if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
 473             goto err;
 474
 475     p = buf;
 476     j = BN_bn2bin(ret, p);      /* j is only used with no-padding mode */
 477
 478     switch (padding) {
 479     case RSA_PKCS1_PADDING:
 480         r = RSA_padding_check_PKCS1_type_2(to, num, buf, j, num);
 481         break;
 482     case RSA_PKCS1_OAEP_PADDING:
 483         r = RSA_padding_check_PKCS1_OAEP(to, num, buf, j, num, NULL, 0);
 484         break;
 485     case RSA_SSLV23_PADDING:
 486         r = RSA_padding_check_SSLv23(to, num, buf, j, num);
 487         break;
 488     case RSA_NO_PADDING:
 489         r = RSA_padding_check_none(to, num, buf, j, num);
 490         break;
 491     default:
 492         RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
 493         goto err;
 494     }
 495     if (r < 0)
 496         RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
 497
 498  err:
 499     if (ctx != NULL)
 500         BN_CTX_end(ctx);
 501     BN_CTX_free(ctx);
 502     OPENSSL_clear_free(buf, num);
 503     return r;
 504 }
 505
 506 /* signature verification */
 507 static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
 508                                   unsigned char *to, RSA *rsa, int padding)
 509 {
 510     BIGNUM *f, *ret;
 511     int i, num = 0, r = -1;
 512     unsigned char *p;
 513     unsigned char *buf = NULL;
 514     BN_CTX *ctx = NULL;
 515
 516     if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
 517         RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_MODULUS_TOO_LARGE);
 518         return -1;
 519     }
 520
 521     if (BN_ucmp(rsa->n, rsa->e) <= 0) {
 522         RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
 523         return -1;
 524     }
 525
 526     /* for large moduli, enforce exponent limit */
 527     if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
 528         if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
 529             RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
 530             return -1;
 531         }
 532     }
 533
 534     if ((ctx = BN_CTX_new()) == NULL)
 535         goto err;
 536     BN_CTX_start(ctx);
 537     f = BN_CTX_get(ctx);
 538     ret = BN_CTX_get(ctx);
 539     num = BN_num_bytes(rsa->n);
 540     buf = OPENSSL_malloc(num);
 541     if (ret == NULL || buf == NULL) {
 542         RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, ERR_R_MALLOC_FAILURE);
 543         goto err;
 544     }
 545
 546     /*
 547      * This check was for equality but PGP does evil things and chops off the
 548      * top '0' bytes
 549      */
 550     if (flen > num) {
 551         RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_DATA_GREATER_THAN_MOD_LEN);
 552         goto err;
 553     }
 554
 555     if (BN_bin2bn(from, flen, f) == NULL)
 556         goto err;
 557
 558     if (BN_ucmp(f, rsa->n) >= 0) {
 559         RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT,
 560                RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
 561         goto err;
 562     }
 563
 564     if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
 565         if (!BN_MONT_CTX_set_locked
 566             (&rsa->_method_mod_n, rsa->lock, rsa->n, ctx))
 567             goto err;
 568
 569     if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
 570                                rsa->_method_mod_n))
 571         goto err;
 572
 573     if ((padding == RSA_X931_PADDING) && ((bn_get_words(ret)[0] & 0xf) != 12))
 574         if (!BN_sub(ret, rsa->n, ret))
 575             goto err;
 576
 577     p = buf;
 578     i = BN_bn2bin(ret, p);
 579
 580     switch (padding) {
 581     case RSA_PKCS1_PADDING:
 582         r = RSA_padding_check_PKCS1_type_1(to, num, buf, i, num);
 583         break;
 584     case RSA_X931_PADDING:
 585         r = RSA_padding_check_X931(to, num, buf, i, num);
 586         break;
 587     case RSA_NO_PADDING:
 588         r = RSA_padding_check_none(to, num, buf, i, num);
 589         break;
 590     default:
 591         RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
 592         goto err;
 593     }
 594     if (r < 0)
 595         RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
 596
 597  err:
 598     if (ctx != NULL)
 599         BN_CTX_end(ctx);
 600     BN_CTX_free(ctx);
 601     OPENSSL_clear_free(buf, num);
 602     return r;
 603 }
 604
 605 static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
 606 {
 607     BIGNUM *r1, *m1, *vrfy, *r2, *m[RSA_MAX_PRIME_NUM - 2];
 608     int ret = 0, i, ex_primes = 0;
 609     RSA_PRIME_INFO *pinfo;
 610
 611     BN_CTX_start(ctx);
 612
 613     r1 = BN_CTX_get(ctx);
 614     r2 = BN_CTX_get(ctx);
 615     m1 = BN_CTX_get(ctx);
 616     vrfy = BN_CTX_get(ctx);
 617     if (vrfy == NULL)
 618         goto err;
 619
 620     if (rsa->version == RSA_ASN1_VERSION_MULTI
 621         && ((ex_primes = sk_RSA_PRIME_INFO_num(rsa->prime_infos)) <= 0
 622              || ex_primes > RSA_MAX_PRIME_NUM - 2))
 623         goto err;
 624
 625     {
 626         BIGNUM *p = BN_new(), *q = BN_new();
 627
 628         /*
 629          * Make sure BN_mod_inverse in Montgomery initialization uses the
 630          * BN_FLG_CONSTTIME flag
 631          */
 632         if (p == NULL || q == NULL) {
 633             BN_free(p);
 634             BN_free(q);
 635             goto err;
 636         }
 637         BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
 638         BN_with_flags(q, rsa->q, BN_FLG_CONSTTIME);
 639
 640         if (rsa->flags & RSA_FLAG_CACHE_PRIVATE) {
 641             if (!BN_MONT_CTX_set_locked
 642                 (&rsa->_method_mod_p, rsa->lock, p, ctx)
 643                 || !BN_MONT_CTX_set_locked(&rsa->_method_mod_q,
 644                                            rsa->lock, q, ctx)) {
 645                 BN_free(p);
 646                 BN_free(q);
 647                 goto err;
 648             }
 649             if (ex_primes > 0) {
 650                 /* cache BN_MONT_CTX for other primes */
 651                 BIGNUM *r = BN_new();
 652
 653                 if (r == NULL) {
 654                     BN_free(p);
 655                     BN_free(q);
 656                     goto err;
 657                 }
 658
 659                 for (i = 0; i < ex_primes; i++) {
 660                     pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
 661                     BN_with_flags(r, pinfo->r, BN_FLG_CONSTTIME);
 662                     if (!BN_MONT_CTX_set_locked(&pinfo->m, rsa->lock, r, ctx)) {
 663                         BN_free(p);
 664                         BN_free(q);
 665                         BN_free(r);
 666                         goto err;
 667                     }
 668                 }
 669                 BN_free(r);
 670             }
 671         }
 672         /*
 673          * We MUST free p and q before any further use of rsa->p and rsa->q
 674          */
 675         BN_free(p);
 676         BN_free(q);
 677     }
 678
 679     if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
 680         if (!BN_MONT_CTX_set_locked
 681             (&rsa->_method_mod_n, rsa->lock, rsa->n, ctx))
 682             goto err;
 683
 684     /* compute I mod q */
 685     {
 686         BIGNUM *c = BN_new();
 687         if (c == NULL)
 688             goto err;
 689         BN_with_flags(c, I, BN_FLG_CONSTTIME);
 690
 691         if (!BN_mod(r1, c, rsa->q, ctx)) {
 692             BN_free(c);
 693             goto err;
 694         }
 695
 696         {
 697             BIGNUM *dmq1 = BN_new();
 698             if (dmq1 == NULL) {
 699                 BN_free(c);
 700                 goto err;
 701             }
 702             BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
 703
 704             /* compute r1^dmq1 mod q */
 705             if (!rsa->meth->bn_mod_exp(m1, r1, dmq1, rsa->q, ctx,
 706                 rsa->_method_mod_q)) {
 707                 BN_free(c);
 708                 BN_free(dmq1);
 709                 goto err;
 710             }
 711             /* We MUST free dmq1 before any further use of rsa->dmq1 */
 712             BN_free(dmq1);
 713         }
 714
 715         /* compute I mod p */
 716         if (!BN_mod(r1, c, rsa->p, ctx)) {
 717             BN_free(c);
 718             goto err;
 719         }
 720         /* We MUST free c before any further use of I */
 721         BN_free(c);
 722     }
 723
 724     {
 725         BIGNUM *dmp1 = BN_new();
 726         if (dmp1 == NULL)
 727             goto err;
 728         BN_with_flags(dmp1, rsa->dmp1, BN_FLG_CONSTTIME);
 729
 730         /* compute r1^dmp1 mod p */
 731         if (!rsa->meth->bn_mod_exp(r0, r1, dmp1, rsa->p, ctx,
 732                                    rsa->_method_mod_p)) {
 733             BN_free(dmp1);
 734             goto err;
 735         }
 736         /* We MUST free dmp1 before any further use of rsa->dmp1 */
 737         BN_free(dmp1);
 738     }
 739
 740     /*
 741      * calculate m_i in multi-prime case
 742      *
 743      * TODO:
 744      * 1. squash the following two loops and calculate |m_i| there.
 745      * 2. remove cc and reuse |c|.
 746      * 3. remove |dmq1| and |dmp1| in previous block and use |di|.
 747      *
 748      * If these things are done, the code will be more readable.
 749      */
 750     if (ex_primes > 0) {
 751         BIGNUM *di = BN_new(), *cc = BN_new();
 752
 753         if (cc == NULL || di == NULL) {
 754             BN_free(cc);
 755             BN_free(di);
 756             goto err;
 757         }
 758
 759         for (i = 0; i < ex_primes; i++) {
 760             /* prepare m_i */
 761             if ((m[i] = BN_CTX_get(ctx)) == NULL) {
 762                 BN_free(cc);
 763                 BN_free(di);
 764                 goto err;
 765             }
 766
 767             pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
 768
 769             /* prepare c and d_i */
 770             BN_with_flags(cc, I, BN_FLG_CONSTTIME);
 771             BN_with_flags(di, pinfo->d, BN_FLG_CONSTTIME);
 772
 773             if (!BN_mod(r1, cc, pinfo->r, ctx)) {
 774                 BN_free(cc);
 775                 BN_free(di);
 776                 goto err;
 777             }
 778             /* compute r1 ^ d_i mod r_i */
 779             if (!rsa->meth->bn_mod_exp(m[i], r1, di, pinfo->r, ctx, pinfo->m)) {
 780                 BN_free(cc);
 781                 BN_free(di);
 782                 goto err;
 783             }
 784         }
 785
 786         BN_free(cc);
 787         BN_free(di);
 788     }
 789
 790     if (!BN_sub(r0, r0, m1))
 791         goto err;
 792     /*
 793      * This will help stop the size of r0 increasing, which does affect the
 794      * multiply if it optimised for a power of 2 size
 795      */
 796     if (BN_is_negative(r0))
 797         if (!BN_add(r0, r0, rsa->p))
 798             goto err;
 799
 800     if (!BN_mul(r1, r0, rsa->iqmp, ctx))
 801         goto err;
 802
 803     {
 804         BIGNUM *pr1 = BN_new();
 805         if (pr1 == NULL)
 806             goto err;
 807         BN_with_flags(pr1, r1, BN_FLG_CONSTTIME);
 808
 809         if (!BN_mod(r0, pr1, rsa->p, ctx)) {
 810             BN_free(pr1);
 811             goto err;
 812         }
 813         /* We MUST free pr1 before any further use of r1 */
 814         BN_free(pr1);
 815     }
 816
 817     /*
 818      * If p < q it is occasionally possible for the correction of adding 'p'
 819      * if r0 is negative above to leave the result still negative. This can
 820      * break the private key operations: the following second correction
 821      * should *always* correct this rare occurrence. This will *never* happen
 822      * with OpenSSL generated keys because they ensure p > q [steve]
 823      */
 824     if (BN_is_negative(r0))
 825         if (!BN_add(r0, r0, rsa->p))
 826             goto err;
 827     if (!BN_mul(r1, r0, rsa->q, ctx))
 828         goto err;
 829     if (!BN_add(r0, r1, m1))
 830         goto err;
 831
 832     /* add m_i to m in multi-prime case */
 833     if (ex_primes > 0) {
 834         BIGNUM *pr2 = BN_new();
 835
 836         if (pr2 == NULL)
 837             goto err;
 838
 839         for (i = 0; i < ex_primes; i++) {
 840             pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
 841             if (!BN_sub(r1, m[i], r0)) {
 842                 BN_free(pr2);
 843                 goto err;
 844             }
 845
 846             if (!BN_mul(r2, r1, pinfo->t, ctx)) {
 847                 BN_free(pr2);
 848                 goto err;
 849             }
 850
 851             BN_with_flags(pr2, r2, BN_FLG_CONSTTIME);
 852
 853             if (!BN_mod(r1, pr2, pinfo->r, ctx)) {
 854                 BN_free(pr2);
 855                 goto err;
 856             }
 857
 858             if (BN_is_negative(r1))
 859                 if (!BN_add(r1, r1, pinfo->r)) {
 860                     BN_free(pr2);
 861                     goto err;
 862                 }
 863             if (!BN_mul(r1, r1, pinfo->pp, ctx)) {
 864                 BN_free(pr2);
 865                 goto err;
 866             }
 867             if (!BN_add(r0, r0, r1)) {
 868                 BN_free(pr2);
 869                 goto err;
 870             }
 871         }
 872         BN_free(pr2);
 873     }
 874
 875     if (rsa->e && rsa->n) {
 876         if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx,
 877                                    rsa->_method_mod_n))
 878             goto err;
 879         /*
 880          * If 'I' was greater than (or equal to) rsa->n, the operation will
 881          * be equivalent to using 'I mod n'. However, the result of the
 882          * verify will *always* be less than 'n' so we don't check for
 883          * absolute equality, just congruency.
 884          */
 885         if (!BN_sub(vrfy, vrfy, I))
 886             goto err;
 887         if (!BN_mod(vrfy, vrfy, rsa->n, ctx))
 888             goto err;
 889         if (BN_is_negative(vrfy))
 890             if (!BN_add(vrfy, vrfy, rsa->n))
 891                 goto err;
 892         if (!BN_is_zero(vrfy)) {
 893             /*
 894              * 'I' and 'vrfy' aren't congruent mod n. Don't leak
 895              * miscalculated CRT output, just do a raw (slower) mod_exp and
 896              * return that instead.
 897              */
 898
 899             BIGNUM *d = BN_new();
 900             if (d == NULL)
 901                 goto err;
 902             BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
 903
 904             if (!rsa->meth->bn_mod_exp(r0, I, d, rsa->n, ctx,
 905                                        rsa->_method_mod_n)) {
 906                 BN_free(d);
 907                 goto err;
 908             }
 909             /* We MUST free d before any further use of rsa->d */
 910             BN_free(d);
 911         }
 912     }
 913     ret = 1;
 914  err:
 915     BN_CTX_end(ctx);
 916     return ret;
 917 }
 918
 919 static int rsa_ossl_init(RSA *rsa)
 920 {
 921     rsa->flags |= RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE;
 922     return 1;
 923 }
 924
 925 static int rsa_ossl_finish(RSA *rsa)
 926 {
 927     int i;
 928     RSA_PRIME_INFO *pinfo;
 929
 930     BN_MONT_CTX_free(rsa->_method_mod_n);
 931     BN_MONT_CTX_free(rsa->_method_mod_p);
 932     BN_MONT_CTX_free(rsa->_method_mod_q);
 933     for (i = 0; i < sk_RSA_PRIME_INFO_num(rsa->prime_infos); i++) {
 934         pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
 935         BN_MONT_CTX_free(pinfo->m);
 936     }
 937     return 1;
 938 }