1 /* 2 * Copyright 2019-2022 The OpenSSL Project Authors. All Rights Reserved. 3 * Copyright 2019 Red Hat, Inc. 4 * 5 * Licensed under the Apache License 2.0 (the "License"). You may not use 6 * this file except in compliance with the License. You can obtain a copy 7 * in the file LICENSE in the source distribution or at 8 * https://www.openssl.org/source/license.html 9 */ 10 11 /* 12 * This implements https://csrc.nist.gov/publications/detail/sp/800-108/final 13 * section 5.1 ("counter mode") and section 5.2 ("feedback mode") in both HMAC 14 * and CMAC. That document does not name the KDFs it defines; the name is 15 * derived from 16 * https://csrc.nist.gov/Projects/Cryptographic-Algorithm-Validation-Program/Key-Derivation 17 * 18 * Note that section 5.3 ("double-pipeline mode") is not implemented, though 19 * it would be possible to do so in the future. 20 * 21 * These versions all assume the counter is used. It would be relatively 22 * straightforward to expose a configuration handle should the need arise. 23 * 24 * Variable names attempt to match those of SP800-108. 25 */ 26 27 #include <stdarg.h> 28 #include <stdlib.h> 29 #include <string.h> 30 31 #include <openssl/core_names.h> 32 #include <openssl/evp.h> 33 #include <openssl/hmac.h> 34 #include <openssl/kdf.h> 35 #include <openssl/params.h> 36 #include <openssl/proverr.h> 37 38 #include "internal/cryptlib.h" 39 #include "crypto/evp.h" 40 #include "internal/numbers.h" 41 #include "internal/endian.h" 42 #include "prov/implementations.h" 43 #include "prov/provider_ctx.h" 44 #include "prov/provider_util.h" 45 #include "prov/providercommon.h" 46 47 #include "e_os.h" 48 49 #define ossl_min(a, b) ((a) < (b)) ? (a) : (b) 50 51 typedef enum { 52 COUNTER = 0, 53 FEEDBACK 54 } kbkdf_mode; 55 56 /* Our context structure. */ 57 typedef struct { 58 void *provctx; 59 kbkdf_mode mode; 60 EVP_MAC_CTX *ctx_init; 61 62 /* Names are lowercased versions of those found in SP800-108. */ 63 unsigned char *ki; 64 size_t ki_len; 65 unsigned char *label; 66 size_t label_len; 67 unsigned char *context; 68 size_t context_len; 69 unsigned char *iv; 70 size_t iv_len; 71 int use_l; 72 int use_separator; 73 } KBKDF; 74 75 /* Definitions needed for typechecking. */ 76 static OSSL_FUNC_kdf_newctx_fn kbkdf_new; 77 static OSSL_FUNC_kdf_freectx_fn kbkdf_free; 78 static OSSL_FUNC_kdf_reset_fn kbkdf_reset; 79 static OSSL_FUNC_kdf_derive_fn kbkdf_derive; 80 static OSSL_FUNC_kdf_settable_ctx_params_fn kbkdf_settable_ctx_params; 81 static OSSL_FUNC_kdf_set_ctx_params_fn kbkdf_set_ctx_params; 82 static OSSL_FUNC_kdf_gettable_ctx_params_fn kbkdf_gettable_ctx_params; 83 static OSSL_FUNC_kdf_get_ctx_params_fn kbkdf_get_ctx_params; 84 85 /* Not all platforms have htobe32(). */ 86 static uint32_t be32(uint32_t host) 87 { 88 uint32_t big = 0; 89 DECLARE_IS_ENDIAN; 90 91 if (!IS_LITTLE_ENDIAN) 92 return host; 93 94 big |= (host & 0xff000000) >> 24; 95 big |= (host & 0x00ff0000) >> 8; 96 big |= (host & 0x0000ff00) << 8; 97 big |= (host & 0x000000ff) << 24; 98 return big; 99 } 100 101 static void init(KBKDF *ctx) 102 { 103 ctx->use_l = 1; 104 ctx->use_separator = 1; 105 } 106 107 static void *kbkdf_new(void *provctx) 108 { 109 KBKDF *ctx; 110 111 if (!ossl_prov_is_running()) 112 return NULL; 113 114 ctx = OPENSSL_zalloc(sizeof(*ctx)); 115 if (ctx == NULL) { 116 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE); 117 return NULL; 118 } 119 120 ctx->provctx = provctx; 121 init(ctx); 122 return ctx; 123 } 124 125 static void kbkdf_free(void *vctx) 126 { 127 KBKDF *ctx = (KBKDF *)vctx; 128 129 if (ctx != NULL) { 130 kbkdf_reset(ctx); 131 OPENSSL_free(ctx); 132 } 133 } 134 135 static void kbkdf_reset(void *vctx) 136 { 137 KBKDF *ctx = (KBKDF *)vctx; 138 void *provctx = ctx->provctx; 139 140 EVP_MAC_CTX_free(ctx->ctx_init); 141 OPENSSL_clear_free(ctx->context, ctx->context_len); 142 OPENSSL_clear_free(ctx->label, ctx->label_len); 143 OPENSSL_clear_free(ctx->ki, ctx->ki_len); 144 OPENSSL_clear_free(ctx->iv, ctx->iv_len); 145 memset(ctx, 0, sizeof(*ctx)); 146 ctx->provctx = provctx; 147 init(ctx); 148 } 149 150 /* SP800-108 section 5.1 or section 5.2 depending on mode. */ 151 static int derive(EVP_MAC_CTX *ctx_init, kbkdf_mode mode, unsigned char *iv, 152 size_t iv_len, unsigned char *label, size_t label_len, 153 unsigned char *context, size_t context_len, 154 unsigned char *k_i, size_t h, uint32_t l, int has_separator, 155 unsigned char *ko, size_t ko_len) 156 { 157 int ret = 0; 158 EVP_MAC_CTX *ctx = NULL; 159 size_t written = 0, to_write, k_i_len = iv_len; 160 const unsigned char zero = 0; 161 uint32_t counter, i; 162 /* 163 * From SP800-108: 164 * The fixed input data is a concatenation of a Label, 165 * a separation indicator 0x00, the Context, and L. 166 * One or more of these fixed input data fields may be omitted. 167 * 168 * has_separator == 0 means that the separator is omitted. 169 * Passing a value of l == 0 means that L is omitted. 170 * The Context and L are omitted automatically if a NULL buffer is passed. 171 */ 172 int has_l = (l != 0); 173 174 /* Setup K(0) for feedback mode. */ 175 if (iv_len > 0) 176 memcpy(k_i, iv, iv_len); 177 178 for (counter = 1; written < ko_len; counter++) { 179 i = be32(counter); 180 181 ctx = EVP_MAC_CTX_dup(ctx_init); 182 if (ctx == NULL) 183 goto done; 184 185 /* Perform feedback, if appropriate. */ 186 if (mode == FEEDBACK && !EVP_MAC_update(ctx, k_i, k_i_len)) 187 goto done; 188 189 if (!EVP_MAC_update(ctx, (unsigned char *)&i, 4) 190 || !EVP_MAC_update(ctx, label, label_len) 191 || (has_separator && !EVP_MAC_update(ctx, &zero, 1)) 192 || !EVP_MAC_update(ctx, context, context_len) 193 || (has_l && !EVP_MAC_update(ctx, (unsigned char *)&l, 4)) 194 || !EVP_MAC_final(ctx, k_i, NULL, h)) 195 goto done; 196 197 to_write = ko_len - written; 198 memcpy(ko + written, k_i, ossl_min(to_write, h)); 199 written += h; 200 201 k_i_len = h; 202 EVP_MAC_CTX_free(ctx); 203 ctx = NULL; 204 } 205 206 ret = 1; 207 done: 208 EVP_MAC_CTX_free(ctx); 209 return ret; 210 } 211 212 static int kbkdf_derive(void *vctx, unsigned char *key, size_t keylen, 213 const OSSL_PARAM params[]) 214 { 215 KBKDF *ctx = (KBKDF *)vctx; 216 int ret = 0; 217 unsigned char *k_i = NULL; 218 uint32_t l = 0; 219 size_t h = 0; 220 221 if (!ossl_prov_is_running() || !kbkdf_set_ctx_params(ctx, params)) 222 return 0; 223 224 /* label, context, and iv are permitted to be empty. Check everything 225 * else. */ 226 if (ctx->ctx_init == NULL) { 227 if (ctx->ki_len == 0 || ctx->ki == NULL) { 228 ERR_raise(ERR_LIB_PROV, PROV_R_NO_KEY_SET); 229 return 0; 230 } 231 /* Could either be missing MAC or missing message digest or missing 232 * cipher - arbitrarily, I pick this one. */ 233 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MAC); 234 return 0; 235 } 236 237 /* Fail if the output length is zero */ 238 if (keylen == 0) { 239 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH); 240 return 0; 241 } 242 243 h = EVP_MAC_CTX_get_mac_size(ctx->ctx_init); 244 if (h == 0) 245 goto done; 246 if (ctx->iv_len != 0 && ctx->iv_len != h) { 247 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_SEED_LENGTH); 248 goto done; 249 } 250 251 if (ctx->use_l != 0) 252 l = be32(keylen * 8); 253 254 k_i = OPENSSL_zalloc(h); 255 if (k_i == NULL) 256 goto done; 257 258 ret = derive(ctx->ctx_init, ctx->mode, ctx->iv, ctx->iv_len, ctx->label, 259 ctx->label_len, ctx->context, ctx->context_len, k_i, h, l, 260 ctx->use_separator, key, keylen); 261 done: 262 if (ret != 1) 263 OPENSSL_cleanse(key, keylen); 264 OPENSSL_clear_free(k_i, h); 265 return ret; 266 } 267 268 static int kbkdf_set_buffer(unsigned char **out, size_t *out_len, 269 const OSSL_PARAM *p) 270 { 271 if (p->data == NULL || p->data_size == 0) 272 return 1; 273 274 OPENSSL_clear_free(*out, *out_len); 275 *out = NULL; 276 return OSSL_PARAM_get_octet_string(p, (void **)out, 0, out_len); 277 } 278 279 static int kbkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[]) 280 { 281 KBKDF *ctx = (KBKDF *)vctx; 282 OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx); 283 const OSSL_PARAM *p; 284 285 if (params == NULL) 286 return 1; 287 288 if (!ossl_prov_macctx_load_from_params(&ctx->ctx_init, params, NULL, 289 NULL, NULL, libctx)) 290 return 0; 291 else if (ctx->ctx_init != NULL 292 && !EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->ctx_init), 293 OSSL_MAC_NAME_HMAC) 294 && !EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->ctx_init), 295 OSSL_MAC_NAME_CMAC)) { 296 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MAC); 297 return 0; 298 } 299 300 p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MODE); 301 if (p != NULL 302 && OPENSSL_strncasecmp("counter", p->data, p->data_size) == 0) { 303 ctx->mode = COUNTER; 304 } else if (p != NULL 305 && OPENSSL_strncasecmp("feedback", p->data, p->data_size) == 0) { 306 ctx->mode = FEEDBACK; 307 } else if (p != NULL) { 308 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE); 309 return 0; 310 } 311 312 p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY); 313 if (p != NULL && !kbkdf_set_buffer(&ctx->ki, &ctx->ki_len, p)) 314 return 0; 315 316 p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SALT); 317 if (p != NULL && !kbkdf_set_buffer(&ctx->label, &ctx->label_len, p)) 318 return 0; 319 320 p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_INFO); 321 if (p != NULL && !kbkdf_set_buffer(&ctx->context, &ctx->context_len, p)) 322 return 0; 323 324 p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SEED); 325 if (p != NULL && !kbkdf_set_buffer(&ctx->iv, &ctx->iv_len, p)) 326 return 0; 327 328 p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KBKDF_USE_L); 329 if (p != NULL && !OSSL_PARAM_get_int(p, &ctx->use_l)) 330 return 0; 331 332 p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KBKDF_USE_SEPARATOR); 333 if (p != NULL && !OSSL_PARAM_get_int(p, &ctx->use_separator)) 334 return 0; 335 336 /* Set up digest context, if we can. */ 337 if (ctx->ctx_init != NULL && ctx->ki_len != 0 338 && !EVP_MAC_init(ctx->ctx_init, ctx->ki, ctx->ki_len, NULL)) 339 return 0; 340 return 1; 341 } 342 343 static const OSSL_PARAM *kbkdf_settable_ctx_params(ossl_unused void *ctx, 344 ossl_unused void *provctx) 345 { 346 static const OSSL_PARAM known_settable_ctx_params[] = { 347 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0), 348 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0), 349 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0), 350 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SEED, NULL, 0), 351 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0), 352 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CIPHER, NULL, 0), 353 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MAC, NULL, 0), 354 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MODE, NULL, 0), 355 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0), 356 OSSL_PARAM_int(OSSL_KDF_PARAM_KBKDF_USE_L, NULL), 357 OSSL_PARAM_int(OSSL_KDF_PARAM_KBKDF_USE_SEPARATOR, NULL), 358 OSSL_PARAM_END, 359 }; 360 return known_settable_ctx_params; 361 } 362 363 static int kbkdf_get_ctx_params(void *vctx, OSSL_PARAM params[]) 364 { 365 OSSL_PARAM *p; 366 367 p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE); 368 if (p == NULL) 369 return -2; 370 371 /* KBKDF can produce results as large as you like. */ 372 return OSSL_PARAM_set_size_t(p, SIZE_MAX); 373 } 374 375 static const OSSL_PARAM *kbkdf_gettable_ctx_params(ossl_unused void *ctx, 376 ossl_unused void *provctx) 377 { 378 static const OSSL_PARAM known_gettable_ctx_params[] = 379 { OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL), OSSL_PARAM_END }; 380 return known_gettable_ctx_params; 381 } 382 383 const OSSL_DISPATCH ossl_kdf_kbkdf_functions[] = { 384 { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kbkdf_new }, 385 { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kbkdf_free }, 386 { OSSL_FUNC_KDF_RESET, (void(*)(void))kbkdf_reset }, 387 { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kbkdf_derive }, 388 { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS, 389 (void(*)(void))kbkdf_settable_ctx_params }, 390 { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kbkdf_set_ctx_params }, 391 { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS, 392 (void(*)(void))kbkdf_gettable_ctx_params }, 393 { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kbkdf_get_ctx_params }, 394 { 0, NULL }, 395 }; 396