providers/implementations/kdfs/krb5kdf.c

   1 /*
   2  * Copyright 2018-2020 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
  25 #include "internal/cryptlib.h"
  26 #include "crypto/evp.h"
  27 #include "internal/numbers.h"
  28 #include "prov/implementations.h"
  29 #include "prov/provider_ctx.h"
  30 #include "prov/provider_util.h"
  31 #include "prov/providercommonerr.h"
  32
  33 /* KRB5 KDF defined in RFC 3961, Section 5.1 */
  34
  35 static OSSL_OP_kdf_newctx_fn krb5kdf_new;
  36 static OSSL_OP_kdf_freectx_fn krb5kdf_free;
  37 static OSSL_OP_kdf_reset_fn krb5kdf_reset;
  38 static OSSL_OP_kdf_derive_fn krb5kdf_derive;
  39 static OSSL_OP_kdf_settable_ctx_params_fn krb5kdf_settable_ctx_params;
  40 static OSSL_OP_kdf_set_ctx_params_fn krb5kdf_set_ctx_params;
  41 static OSSL_OP_kdf_gettable_ctx_params_fn krb5kdf_gettable_ctx_params;
  42 static OSSL_OP_kdf_get_ctx_params_fn krb5kdf_get_ctx_params;
  43
  44 static int KRB5KDF(const EVP_CIPHER *cipher, ENGINE *engine,
  45                    const unsigned char *key, size_t key_len,
  46                    const unsigned char *constant, size_t constant_len,
  47                    unsigned char *okey, size_t okey_len);
  48
  49 typedef struct {
  50     void *provctx;
  51     PROV_CIPHER cipher;
  52     unsigned char *key;
  53     size_t key_len;
  54     unsigned char *constant;
  55     size_t constant_len;
  56 } KRB5KDF_CTX;
  57
  58 static void *krb5kdf_new(void *provctx)
  59 {
  60     KRB5KDF_CTX *ctx;
  61
  62     if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
  63         ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
  64     ctx->provctx = provctx;
  65     return ctx;
  66 }
  67
  68 static void krb5kdf_free(void *vctx)
  69 {
  70     KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;
  71
  72     if (ctx != NULL) {
  73         krb5kdf_reset(ctx);
  74         OPENSSL_free(ctx);
  75     }
  76 }
  77
  78 static void krb5kdf_reset(void *vctx)
  79 {
  80     KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;
  81
  82     ossl_prov_cipher_reset(&ctx->cipher);
  83     OPENSSL_clear_free(ctx->key, ctx->key_len);
  84     OPENSSL_clear_free(ctx->constant, ctx->constant_len);
  85     memset(ctx, 0, sizeof(*ctx));
  86 }
  87
  88 static int krb5kdf_set_membuf(unsigned char **dst, size_t *dst_len,
  89                               const OSSL_PARAM *p)
  90 {
  91     OPENSSL_clear_free(*dst, *dst_len);
  92     *dst = NULL;
  93     return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);
  94 }
  95
  96 static int krb5kdf_derive(void *vctx, unsigned char *key,
  97                               size_t keylen)
  98 {
  99     KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;
 100     const EVP_CIPHER *cipher = ossl_prov_cipher_cipher(&ctx->cipher);
 101     ENGINE *engine = ossl_prov_cipher_engine(&ctx->cipher);
 102
 103     if (cipher == NULL) {
 104         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_CIPHER);
 105         return 0;
 106     }
 107     if (ctx->key == NULL) {
 108         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
 109         return 0;
 110     }
 111     if (ctx->constant == NULL) {
 112         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_CONSTANT);
 113         return 0;
 114     }
 115     return KRB5KDF(cipher, engine, ctx->key, ctx->key_len,
 116                    ctx->constant, ctx->constant_len,
 117                    key, keylen);
 118 }
 119
 120 static int krb5kdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 121 {
 122     const OSSL_PARAM *p;
 123     KRB5KDF_CTX *ctx = vctx;
 124     OPENSSL_CTX *provctx = PROV_LIBRARY_CONTEXT_OF(ctx->provctx);
 125
 126     if (!ossl_prov_cipher_load_from_params(&ctx->cipher, params, provctx))
 127         return 0;
 128
 129     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
 130         if (!krb5kdf_set_membuf(&ctx->key, &ctx->key_len, p))
 131             return 0;
 132
 133     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_CONSTANT))
 134         != NULL)
 135         if (!krb5kdf_set_membuf(&ctx->constant, &ctx->constant_len, p))
 136             return 0;
 137
 138     return 1;
 139 }
 140
 141 static const OSSL_PARAM *krb5kdf_settable_ctx_params(void)
 142 {
 143     static const OSSL_PARAM known_settable_ctx_params[] = {
 144         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
 145         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CIPHER, NULL, 0),
 146         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
 147         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_CONSTANT, NULL, 0),
 148         OSSL_PARAM_END
 149     };
 150     return known_settable_ctx_params;
 151 }
 152
 153 static int krb5kdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
 154 {
 155     KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;
 156     const EVP_CIPHER *cipher;
 157     size_t len;
 158     OSSL_PARAM *p;
 159
 160     cipher = ossl_prov_cipher_cipher(&ctx->cipher);
 161     if (cipher)
 162         len = EVP_CIPHER_key_length(cipher);
 163     else
 164         len = EVP_MAX_KEY_LENGTH;
 165
 166     if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
 167         return OSSL_PARAM_set_size_t(p, len);
 168     return -2;
 169 }
 170
 171 static const OSSL_PARAM *krb5kdf_gettable_ctx_params(void)
 172 {
 173     static const OSSL_PARAM known_gettable_ctx_params[] = {
 174         OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
 175         OSSL_PARAM_END
 176     };
 177     return known_gettable_ctx_params;
 178 }
 179
 180 const OSSL_DISPATCH kdf_krb5kdf_functions[] = {
 181     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))krb5kdf_new },
 182     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))krb5kdf_free },
 183     { OSSL_FUNC_KDF_RESET, (void(*)(void))krb5kdf_reset },
 184     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))krb5kdf_derive },
 185     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 186       (void(*)(void))krb5kdf_settable_ctx_params },
 187     { OSSL_FUNC_KDF_SET_CTX_PARAMS,
 188       (void(*)(void))krb5kdf_set_ctx_params },
 189     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 190       (void(*)(void))krb5kdf_gettable_ctx_params },
 191     { OSSL_FUNC_KDF_GET_CTX_PARAMS,
 192       (void(*)(void))krb5kdf_get_ctx_params },
 193     { 0, NULL }
 194 };
 195
 196 #ifndef OPENSSL_NO_DES
 197 /*
 198  * DES3 is a special case, it requires a random-to-key function and its
 199  * input truncated to 21 bytes of the 24 produced by the cipher.
 200  * See RFC3961 6.3.1
 201  */
 202 static int fixup_des3_key(unsigned char *key)
 203 {
 204     unsigned char *cblock;
 205     int i, j;
 206
 207     for (i = 2; i >= 0; i--) {
 208         cblock = &key[i * 8];
 209         memmove(cblock, &key[i * 7], 7);
 210         cblock[7] = 0;
 211         for (j = 0; j < 7; j++)
 212             cblock[7] |= (cblock[j] & 1) << (j + 1);
 213         DES_set_odd_parity((DES_cblock *)cblock);
 214     }
 215
 216     /* fail if keys are such that triple des degrades to single des */
 217     if (CRYPTO_memcmp(&key[0], &key[8], 8) == 0 ||
 218         CRYPTO_memcmp(&key[8], &key[16], 8) == 0) {
 219         return 0;
 220     }
 221
 222     return 1;
 223 }
 224 #endif
 225
 226 /*
 227  * N-fold(K) where blocksize is N, and constant_len is K
 228  * Note: Here |= denotes concatenation
 229  *
 230  * L = lcm(N,K)
 231  * R = L/K
 232  *
 233  * for r: 1 -> R
 234  *   s |= constant rot 13*(r-1))
 235  *
 236  * block = 0
 237  * for k: 1 -> K
 238  *   block += s[N(k-1)..(N-1)k] (one's complement addition)
 239  *
 240  * Optimizing for space we compute:
 241  * for each l in L-1 -> 0:
 242  *   s[l] = (constant rot 13*(l/K))[l%k]
 243  *   block[l % N] += s[l] (with carry)
 244  * finally add carry if any
 245  */
 246 static void n_fold(unsigned char *block, unsigned int blocksize,
 247                    const unsigned char *constant, size_t constant_len)
 248 {
 249     unsigned int tmp, gcd, remainder, lcm, carry;
 250     int b, l;
 251
 252     if (constant_len == blocksize) {
 253         memcpy(block, constant, constant_len);
 254         return;
 255     }
 256
 257     /* Least Common Multiple of lengths: LCM(a,b)*/
 258     gcd = blocksize;
 259     remainder = constant_len;
 260     /* Calculate Great Common Divisor first GCD(a,b) */
 261     while (remainder != 0) {
 262         tmp = gcd % remainder;
 263         gcd = remainder;
 264         remainder = tmp;
 265     }
 266     /* resulting a is the GCD, LCM(a,b) = |a*b|/GCD(a,b) */
 267     lcm = blocksize * constant_len / gcd;
 268
 269     /* now spread out the bits */
 270     memset(block, 0, blocksize);
 271
 272     /* last to first to be able to bring carry forward */
 273     carry = 0;
 274     for (l = lcm - 1; l >= 0; l--) {
 275         unsigned int rotbits, rshift, rbyte;
 276
 277         /* destination byte in block is l % N */
 278         b = l % blocksize;
 279         /* Our virtual s buffer is R = L/K long (K = constant_len) */
 280         /* So we rotate backwards from R-1 to 0 (none) rotations */
 281         rotbits = 13 * (l / constant_len);
 282         /* find the byte on s where rotbits falls onto */
 283         rbyte = l - (rotbits / 8);
 284         /* calculate how much shift on that byte */
 285         rshift = rotbits & 0x07;
 286         /* rbyte % constant_len gives us the unrotated byte in the
 287          * constant buffer, get also the previous byte then
 288          * appropriately shift them to get the rotated byte we need */
 289         tmp = (constant[(rbyte-1) % constant_len] << (8 - rshift)
 290                | constant[rbyte % constant_len] >> rshift)
 291               & 0xff;
 292         /* add with carry to any value placed by previous passes */
 293         tmp += carry + block[b];
 294         block[b] = tmp & 0xff;
 295         /* save any carry that may be left */
 296         carry = tmp >> 8;
 297     }
 298
 299     /* if any carry is left at the end, add it through the number */
 300     for (b = blocksize - 1; b >= 0 && carry != 0; b--) {
 301         carry += block[b];
 302         block[b] = carry & 0xff;
 303         carry >>= 8;
 304     }
 305 }
 306
 307 static int cipher_init(EVP_CIPHER_CTX *ctx,
 308                        const EVP_CIPHER *cipher, ENGINE *engine,
 309                        const unsigned char *key, size_t key_len)
 310 {
 311     int klen, ret;
 312
 313     ret = EVP_EncryptInit_ex(ctx, cipher, engine, key, NULL);
 314     if (!ret)
 315         goto out;
 316     /* set the key len for the odd variable key len cipher */
 317     klen = EVP_CIPHER_CTX_key_length(ctx);
 318     if (key_len != (size_t)klen) {
 319         ret = EVP_CIPHER_CTX_set_key_length(ctx, key_len);
 320         if (!ret)
 321             goto out;
 322     }
 323     /* we never want padding, either the length requested is a multiple of
 324      * the cipher block size or we are passed a cipher that can cope with
 325      * partial blocks via techniques like cipher text stealing */
 326     ret = EVP_CIPHER_CTX_set_padding(ctx, 0);
 327     if (!ret)
 328         goto out;
 329
 330 out:
 331     return ret;
 332 }
 333
 334 static int KRB5KDF(const EVP_CIPHER *cipher, ENGINE *engine,
 335                    const unsigned char *key, size_t key_len,
 336                    const unsigned char *constant, size_t constant_len,
 337                    unsigned char *okey, size_t okey_len)
 338 {
 339     EVP_CIPHER_CTX *ctx = NULL;
 340     unsigned char block[EVP_MAX_BLOCK_LENGTH * 2];
 341     unsigned char *plainblock, *cipherblock;
 342     size_t blocksize;
 343     size_t cipherlen;
 344     size_t osize;
 345 #ifndef OPENSSL_NO_DES
 346     int des3_no_fixup = 0;
 347 #endif
 348     int ret;
 349
 350     if (key_len != okey_len) {
 351 #ifndef OPENSSL_NO_DES
 352         /* special case for 3des, where the caller may be requesting
 353          * the random raw key, instead of the fixed up key  */
 354         if (EVP_CIPHER_nid(cipher) == NID_des_ede3_cbc &&
 355             key_len == 24 && okey_len == 21) {
 356                 des3_no_fixup = 1;
 357         } else {
 358 #endif
 359             ERR_raise(ERR_LIB_PROV, PROV_R_WRONG_OUTPUT_BUFFER_SIZE);
 360             return 0;
 361 #ifndef OPENSSL_NO_DES
 362         }
 363 #endif
 364     }
 365
 366     ctx = EVP_CIPHER_CTX_new();
 367     if (ctx == NULL)
 368         return 0;
 369
 370     ret = cipher_init(ctx, cipher, engine, key, key_len);
 371     if (!ret)
 372         goto out;
 373
 374     /* Initialize input block */
 375     blocksize = EVP_CIPHER_CTX_block_size(ctx);
 376
 377     if (constant_len > blocksize) {
 378         ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_CONSTANT_LENGTH);
 379         ret = 0;
 380         goto out;
 381     }
 382
 383     n_fold(block, blocksize, constant, constant_len);
 384     plainblock = block;
 385     cipherblock = block + EVP_MAX_BLOCK_LENGTH;
 386
 387     for (osize = 0; osize < okey_len; osize += cipherlen) {
 388         int olen;
 389
 390         ret = EVP_EncryptUpdate(ctx, cipherblock, &olen,
 391                                 plainblock, blocksize);
 392         if (!ret)
 393             goto out;
 394         cipherlen = olen;
 395         ret = EVP_EncryptFinal_ex(ctx, cipherblock, &olen);
 396         if (!ret)
 397             goto out;
 398         if (olen != 0) {
 399             ERR_raise(ERR_LIB_PROV, PROV_R_WRONG_FINAL_BLOCK_LENGTH);
 400             ret = 0;
 401             goto out;
 402         }
 403
 404         /* write cipherblock out */
 405         if (cipherlen > okey_len - osize)
 406             cipherlen = okey_len - osize;
 407         memcpy(okey + osize, cipherblock, cipherlen);
 408
 409         if (okey_len > osize + cipherlen) {
 410             /* we need to reinitialize cipher context per spec */
 411             ret = EVP_CIPHER_CTX_reset(ctx);
 412             if (!ret)
 413                 goto out;
 414             ret = cipher_init(ctx, cipher, engine, key, key_len);
 415             if (!ret)
 416                 goto out;
 417
 418             /* also swap block offsets so last ciphertext becomes new
 419              * plaintext */
 420             plainblock = cipherblock;
 421             if (cipherblock == block) {
 422                 cipherblock += EVP_MAX_BLOCK_LENGTH;
 423             } else {
 424                 cipherblock = block;
 425             }
 426         }
 427     }
 428
 429 #ifndef OPENSSL_NO_DES
 430     if (EVP_CIPHER_nid(cipher) == NID_des_ede3_cbc && !des3_no_fixup) {
 431         ret = fixup_des3_key(okey);
 432         if (!ret) {
 433             ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_GENERATE_KEY);
 434             goto out;
 435         }
 436     }
 437 #endif
 438
 439     ret = 1;
 440
 441 out:
 442     EVP_CIPHER_CTX_free(ctx);
 443     OPENSSL_cleanse(block, EVP_MAX_BLOCK_LENGTH * 2);
 444     return ret;
 445 }
 446