providers/implementations/kdfs/krb5kdf.c

   1 /*
   2  * Copyright 2018-2024 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 /*
  11  * DES low level APIs are deprecated for public use, but still ok for internal
  12  * use.  We access the DES_set_odd_parity(3) function here.
  13  */
  14 #include "internal/deprecated.h"
  15
  16 #include <stdlib.h>
  17 #include <stdarg.h>
  18 #include <string.h>
  19
  20 #include <openssl/core_names.h>
  21 #include <openssl/des.h>
  22 #include <openssl/evp.h>
  23 #include <openssl/kdf.h>
  24 #include <openssl/proverr.h>
  25
  26 #include "internal/cryptlib.h"
  27 #include "crypto/evp.h"
  28 #include "internal/numbers.h"
  29 #include "prov/implementations.h"
  30 #include "prov/provider_ctx.h"
  31 #include "prov/provider_util.h"
  32 #include "prov/providercommon.h"
  33
  34 /* KRB5 KDF defined in RFC 3961, Section 5.1 */
  35
  36 static OSSL_FUNC_kdf_newctx_fn krb5kdf_new;
  37 static OSSL_FUNC_kdf_dupctx_fn krb5kdf_dup;
  38 static OSSL_FUNC_kdf_freectx_fn krb5kdf_free;
  39 static OSSL_FUNC_kdf_reset_fn krb5kdf_reset;
  40 static OSSL_FUNC_kdf_derive_fn krb5kdf_derive;
  41 static OSSL_FUNC_kdf_settable_ctx_params_fn krb5kdf_settable_ctx_params;
  42 static OSSL_FUNC_kdf_set_ctx_params_fn krb5kdf_set_ctx_params;
  43 static OSSL_FUNC_kdf_gettable_ctx_params_fn krb5kdf_gettable_ctx_params;
  44 static OSSL_FUNC_kdf_get_ctx_params_fn krb5kdf_get_ctx_params;
  45
  46 static int KRB5KDF(const EVP_CIPHER *cipher, ENGINE *engine,
  47                    const unsigned char *key, size_t key_len,
  48                    const unsigned char *constant, size_t constant_len,
  49                    unsigned char *okey, size_t okey_len);
  50
  51 typedef struct {
  52     void *provctx;
  53     PROV_CIPHER cipher;
  54     unsigned char *key;
  55     size_t key_len;
  56     unsigned char *constant;
  57     size_t constant_len;
  58 } KRB5KDF_CTX;
  59
  60 static void *krb5kdf_new(void *provctx)
  61 {
  62     KRB5KDF_CTX *ctx;
  63
  64     if (!ossl_prov_is_running())
  65         return NULL;
  66
  67     if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
  68         return NULL;
  69     ctx->provctx = provctx;
  70     return ctx;
  71 }
  72
  73 static void krb5kdf_free(void *vctx)
  74 {
  75     KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;
  76
  77     if (ctx != NULL) {
  78         krb5kdf_reset(ctx);
  79         OPENSSL_free(ctx);
  80     }
  81 }
  82
  83 static void krb5kdf_reset(void *vctx)
  84 {
  85     KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;
  86     void *provctx = ctx->provctx;
  87
  88     ossl_prov_cipher_reset(&ctx->cipher);
  89     OPENSSL_clear_free(ctx->key, ctx->key_len);
  90     OPENSSL_clear_free(ctx->constant, ctx->constant_len);
  91     memset(ctx, 0, sizeof(*ctx));
  92     ctx->provctx = provctx;
  93 }
  94
  95 static int krb5kdf_set_membuf(unsigned char **dst, size_t *dst_len,
  96                               const OSSL_PARAM *p)
  97 {
  98     OPENSSL_clear_free(*dst, *dst_len);
  99     *dst = NULL;
 100     *dst_len = 0;
 101     return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);
 102 }
 103
 104 static void *krb5kdf_dup(void *vctx)
 105 {
 106     const KRB5KDF_CTX *src = (const KRB5KDF_CTX *)vctx;
 107     KRB5KDF_CTX *dest;
 108
 109     dest = krb5kdf_new(src->provctx);
 110     if (dest != NULL) {
 111         if (!ossl_prov_memdup(src->key, src->key_len,
 112                               &dest->key, &dest->key_len)
 113                 || !ossl_prov_memdup(src->constant, src->constant_len,
 114                                      &dest->constant , &dest->constant_len)
 115                 || !ossl_prov_cipher_copy(&dest->cipher, &src->cipher))
 116             goto err;
 117     }
 118     return dest;
 119
 120  err:
 121     krb5kdf_free(dest);
 122     return NULL;
 123 }
 124
 125 static int krb5kdf_derive(void *vctx, unsigned char *key, size_t keylen,
 126                           const OSSL_PARAM params[])
 127 {
 128     KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;
 129     const EVP_CIPHER *cipher;
 130     ENGINE *engine;
 131
 132     if (!ossl_prov_is_running() || !krb5kdf_set_ctx_params(ctx, params))
 133         return 0;
 134
 135     cipher = ossl_prov_cipher_cipher(&ctx->cipher);
 136     if (cipher == NULL) {
 137         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_CIPHER);
 138         return 0;
 139     }
 140     if (ctx->key == NULL) {
 141         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
 142         return 0;
 143     }
 144     if (ctx->constant == NULL) {
 145         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_CONSTANT);
 146         return 0;
 147     }
 148     engine = ossl_prov_cipher_engine(&ctx->cipher);
 149     return KRB5KDF(cipher, engine, ctx->key, ctx->key_len,
 150                    ctx->constant, ctx->constant_len,
 151                    key, keylen);
 152 }
 153
 154 static int krb5kdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 155 {
 156     const OSSL_PARAM *p;
 157     KRB5KDF_CTX *ctx = vctx;
 158     OSSL_LIB_CTX *provctx = PROV_LIBCTX_OF(ctx->provctx);
 159
 160     if (params == NULL)
 161         return 1;
 162
 163     if (!ossl_prov_cipher_load_from_params(&ctx->cipher, params, provctx))
 164         return 0;
 165
 166     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
 167         if (!krb5kdf_set_membuf(&ctx->key, &ctx->key_len, p))
 168             return 0;
 169
 170     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_CONSTANT))
 171         != NULL)
 172         if (!krb5kdf_set_membuf(&ctx->constant, &ctx->constant_len, p))
 173             return 0;
 174
 175     return 1;
 176 }
 177
 178 static const OSSL_PARAM *krb5kdf_settable_ctx_params(ossl_unused void *ctx,
 179                                                      ossl_unused void *provctx)
 180 {
 181     static const OSSL_PARAM known_settable_ctx_params[] = {
 182         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
 183         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CIPHER, NULL, 0),
 184         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
 185         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_CONSTANT, NULL, 0),
 186         OSSL_PARAM_END
 187     };
 188     return known_settable_ctx_params;
 189 }
 190
 191 static int krb5kdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
 192 {
 193     KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;
 194     const EVP_CIPHER *cipher;
 195     size_t len;
 196     OSSL_PARAM *p;
 197
 198     cipher = ossl_prov_cipher_cipher(&ctx->cipher);
 199     if (cipher)
 200         len = EVP_CIPHER_get_key_length(cipher);
 201     else
 202         len = EVP_MAX_KEY_LENGTH;
 203
 204     if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
 205         return OSSL_PARAM_set_size_t(p, len);
 206     return -2;
 207 }
 208
 209 static const OSSL_PARAM *krb5kdf_gettable_ctx_params(ossl_unused void *ctx,
 210                                                      ossl_unused void *provctx)
 211 {
 212     static const OSSL_PARAM known_gettable_ctx_params[] = {
 213         OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
 214         OSSL_PARAM_END
 215     };
 216     return known_gettable_ctx_params;
 217 }
 218
 219 const OSSL_DISPATCH ossl_kdf_krb5kdf_functions[] = {
 220     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))krb5kdf_new },
 221     { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))krb5kdf_dup },
 222     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))krb5kdf_free },
 223     { OSSL_FUNC_KDF_RESET, (void(*)(void))krb5kdf_reset },
 224     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))krb5kdf_derive },
 225     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 226       (void(*)(void))krb5kdf_settable_ctx_params },
 227     { OSSL_FUNC_KDF_SET_CTX_PARAMS,
 228       (void(*)(void))krb5kdf_set_ctx_params },
 229     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 230       (void(*)(void))krb5kdf_gettable_ctx_params },
 231     { OSSL_FUNC_KDF_GET_CTX_PARAMS,
 232       (void(*)(void))krb5kdf_get_ctx_params },
 233     OSSL_DISPATCH_END
 234 };
 235
 236 #ifndef OPENSSL_NO_DES
 237 /*
 238  * DES3 is a special case, it requires a random-to-key function and its
 239  * input truncated to 21 bytes of the 24 produced by the cipher.
 240  * See RFC3961 6.3.1
 241  */
 242 static int fixup_des3_key(unsigned char *key)
 243 {
 244     unsigned char *cblock;
 245     int i, j;
 246
 247     for (i = 2; i >= 0; i--) {
 248         cblock = &key[i * 8];
 249         memmove(cblock, &key[i * 7], 7);
 250         cblock[7] = 0;
 251         for (j = 0; j < 7; j++)
 252             cblock[7] |= (cblock[j] & 1) << (j + 1);
 253         DES_set_odd_parity((DES_cblock *)cblock);
 254     }
 255
 256     /* fail if keys are such that triple des degrades to single des */
 257     if (CRYPTO_memcmp(&key[0], &key[8], 8) == 0 ||
 258         CRYPTO_memcmp(&key[8], &key[16], 8) == 0) {
 259         return 0;
 260     }
 261
 262     return 1;
 263 }
 264 #endif
 265
 266 /*
 267  * N-fold(K) where blocksize is N, and constant_len is K
 268  * Note: Here |= denotes concatenation
 269  *
 270  * L = lcm(N,K)
 271  * R = L/K
 272  *
 273  * for r: 1 -> R
 274  *   s |= constant rot 13*(r-1))
 275  *
 276  * block = 0
 277  * for k: 1 -> K
 278  *   block += s[N(k-1)..(N-1)k] (one's complement addition)
 279  *
 280  * Optimizing for space we compute:
 281  * for each l in L-1 -> 0:
 282  *   s[l] = (constant rot 13*(l/K))[l%k]
 283  *   block[l % N] += s[l] (with carry)
 284  * finally add carry if any
 285  */
 286 static void n_fold(unsigned char *block, unsigned int blocksize,
 287                    const unsigned char *constant, size_t constant_len)
 288 {
 289     unsigned int tmp, gcd, remainder, lcm, carry;
 290     int b, l;
 291
 292     if (constant_len == blocksize) {
 293         memcpy(block, constant, constant_len);
 294         return;
 295     }
 296
 297     /* Least Common Multiple of lengths: LCM(a,b)*/
 298     gcd = blocksize;
 299     remainder = constant_len;
 300     /* Calculate Great Common Divisor first GCD(a,b) */
 301     while (remainder != 0) {
 302         tmp = gcd % remainder;
 303         gcd = remainder;
 304         remainder = tmp;
 305     }
 306     /* resulting a is the GCD, LCM(a,b) = |a*b|/GCD(a,b) */
 307     lcm = blocksize * constant_len / gcd;
 308
 309     /* now spread out the bits */
 310     memset(block, 0, blocksize);
 311
 312     /* last to first to be able to bring carry forward */
 313     carry = 0;
 314     for (l = lcm - 1; l >= 0; l--) {
 315         unsigned int rotbits, rshift, rbyte;
 316
 317         /* destination byte in block is l % N */
 318         b = l % blocksize;
 319         /* Our virtual s buffer is R = L/K long (K = constant_len) */
 320         /* So we rotate backwards from R-1 to 0 (none) rotations */
 321         rotbits = 13 * (l / constant_len);
 322         /* find the byte on s where rotbits falls onto */
 323         rbyte = l - (rotbits / 8);
 324         /* calculate how much shift on that byte */
 325         rshift = rotbits & 0x07;
 326         /* rbyte % constant_len gives us the unrotated byte in the
 327          * constant buffer, get also the previous byte then
 328          * appropriately shift them to get the rotated byte we need */
 329         tmp = (constant[(rbyte-1) % constant_len] << (8 - rshift)
 330                | constant[rbyte % constant_len] >> rshift)
 331               & 0xff;
 332         /* add with carry to any value placed by previous passes */
 333         tmp += carry + block[b];
 334         block[b] = tmp & 0xff;
 335         /* save any carry that may be left */
 336         carry = tmp >> 8;
 337     }
 338
 339     /* if any carry is left at the end, add it through the number */
 340     for (b = blocksize - 1; b >= 0 && carry != 0; b--) {
 341         carry += block[b];
 342         block[b] = carry & 0xff;
 343         carry >>= 8;
 344     }
 345 }
 346
 347 static int cipher_init(EVP_CIPHER_CTX *ctx,
 348                        const EVP_CIPHER *cipher, ENGINE *engine,
 349                        const unsigned char *key, size_t key_len)
 350 {
 351     int klen, ret;
 352
 353     ret = EVP_EncryptInit_ex(ctx, cipher, engine, key, NULL);
 354     if (!ret)
 355         goto out;
 356     /* set the key len for the odd variable key len cipher */
 357     klen = EVP_CIPHER_CTX_get_key_length(ctx);
 358     if (key_len != (size_t)klen) {
 359         ret = EVP_CIPHER_CTX_set_key_length(ctx, key_len);
 360         if (ret <= 0) {
 361             ret = 0;
 362             goto out;
 363         }
 364     }
 365     /* we never want padding, either the length requested is a multiple of
 366      * the cipher block size or we are passed a cipher that can cope with
 367      * partial blocks via techniques like cipher text stealing */
 368     ret = EVP_CIPHER_CTX_set_padding(ctx, 0);
 369     if (!ret)
 370         goto out;
 371
 372 out:
 373     return ret;
 374 }
 375
 376 static int KRB5KDF(const EVP_CIPHER *cipher, ENGINE *engine,
 377                    const unsigned char *key, size_t key_len,
 378                    const unsigned char *constant, size_t constant_len,
 379                    unsigned char *okey, size_t okey_len)
 380 {
 381     EVP_CIPHER_CTX *ctx = NULL;
 382     unsigned char block[EVP_MAX_BLOCK_LENGTH * 2];
 383     unsigned char *plainblock, *cipherblock;
 384     size_t blocksize;
 385     size_t cipherlen;
 386     size_t osize;
 387 #ifndef OPENSSL_NO_DES
 388     int des3_no_fixup = 0;
 389 #endif
 390     int ret;
 391
 392     if (key_len != okey_len) {
 393 #ifndef OPENSSL_NO_DES
 394         /* special case for 3des, where the caller may be requesting
 395          * the random raw key, instead of the fixed up key  */
 396         if (EVP_CIPHER_get_nid(cipher) == NID_des_ede3_cbc &&
 397             key_len == 24 && okey_len == 21) {
 398                 des3_no_fixup = 1;
 399         } else {
 400 #endif
 401             ERR_raise(ERR_LIB_PROV, PROV_R_WRONG_OUTPUT_BUFFER_SIZE);
 402             return 0;
 403 #ifndef OPENSSL_NO_DES
 404         }
 405 #endif
 406     }
 407
 408     ctx = EVP_CIPHER_CTX_new();
 409     if (ctx == NULL)
 410         return 0;
 411
 412     ret = cipher_init(ctx, cipher, engine, key, key_len);
 413     if (!ret)
 414         goto out;
 415
 416     /* Initialize input block */
 417     blocksize = EVP_CIPHER_CTX_get_block_size(ctx);
 418
 419     if (blocksize == 0) {
 420         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_CIPHER);
 421         ret = 0;
 422         goto out;
 423     }
 424
 425     if (constant_len > blocksize) {
 426         ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_CONSTANT_LENGTH);
 427         ret = 0;
 428         goto out;
 429     }
 430
 431     n_fold(block, blocksize, constant, constant_len);
 432     plainblock = block;
 433     cipherblock = block + EVP_MAX_BLOCK_LENGTH;
 434
 435     for (osize = 0; osize < okey_len; osize += cipherlen) {
 436         int olen;
 437
 438         ret = EVP_EncryptUpdate(ctx, cipherblock, &olen,
 439                                 plainblock, blocksize);
 440         if (!ret)
 441             goto out;
 442         cipherlen = olen;
 443         ret = EVP_EncryptFinal_ex(ctx, cipherblock, &olen);
 444         if (!ret)
 445             goto out;
 446         if (olen != 0) {
 447             ERR_raise(ERR_LIB_PROV, PROV_R_WRONG_FINAL_BLOCK_LENGTH);
 448             ret = 0;
 449             goto out;
 450         }
 451
 452         /* write cipherblock out */
 453         if (cipherlen > okey_len - osize)
 454             cipherlen = okey_len - osize;
 455         memcpy(okey + osize, cipherblock, cipherlen);
 456
 457         if (okey_len > osize + cipherlen) {
 458             /* we need to reinitialize cipher context per spec */
 459             ret = EVP_CIPHER_CTX_reset(ctx);
 460             if (!ret)
 461                 goto out;
 462             ret = cipher_init(ctx, cipher, engine, key, key_len);
 463             if (!ret)
 464                 goto out;
 465
 466             /* also swap block offsets so last ciphertext becomes new
 467              * plaintext */
 468             plainblock = cipherblock;
 469             if (cipherblock == block) {
 470                 cipherblock += EVP_MAX_BLOCK_LENGTH;
 471             } else {
 472                 cipherblock = block;
 473             }
 474         }
 475     }
 476
 477 #ifndef OPENSSL_NO_DES
 478     if (EVP_CIPHER_get_nid(cipher) == NID_des_ede3_cbc && !des3_no_fixup) {
 479         ret = fixup_des3_key(okey);
 480         if (!ret) {
 481             ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_GENERATE_KEY);
 482             goto out;
 483         }
 484     }
 485 #endif
 486
 487     ret = 1;
 488
 489 out:
 490     EVP_CIPHER_CTX_free(ctx);
 491     OPENSSL_cleanse(block, EVP_MAX_BLOCK_LENGTH * 2);
 492     return ret;
 493 }
 494