Jens Wiklander | 817466c | 2018-05-22 13:49:31 +0200 | [diff] [blame^] | 1 | /* |
| 2 | * Entropy accumulator implementation |
| 3 | * |
| 4 | * Copyright (C) 2006-2016, ARM Limited, All Rights Reserved |
| 5 | * SPDX-License-Identifier: Apache-2.0 |
| 6 | * |
| 7 | * Licensed under the Apache License, Version 2.0 (the "License"); you may |
| 8 | * not use this file except in compliance with the License. |
| 9 | * You may obtain a copy of the License at |
| 10 | * |
| 11 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | * |
| 13 | * Unless required by applicable law or agreed to in writing, software |
| 14 | * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| 15 | * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 | * See the License for the specific language governing permissions and |
| 17 | * limitations under the License. |
| 18 | * |
| 19 | * This file is part of mbed TLS (https://tls.mbed.org) |
| 20 | */ |
| 21 | |
| 22 | #if !defined(MBEDTLS_CONFIG_FILE) |
| 23 | #include "mbedtls/config.h" |
| 24 | #else |
| 25 | #include MBEDTLS_CONFIG_FILE |
| 26 | #endif |
| 27 | |
| 28 | #if defined(MBEDTLS_ENTROPY_C) |
| 29 | |
| 30 | #if defined(MBEDTLS_TEST_NULL_ENTROPY) |
| 31 | #warning "**** WARNING! MBEDTLS_TEST_NULL_ENTROPY defined! " |
| 32 | #warning "**** THIS BUILD HAS NO DEFINED ENTROPY SOURCES " |
| 33 | #warning "**** THIS BUILD IS *NOT* SUITABLE FOR PRODUCTION USE " |
| 34 | #endif |
| 35 | |
| 36 | #include "mbedtls/entropy.h" |
| 37 | #include "mbedtls/entropy_poll.h" |
| 38 | |
| 39 | #include <string.h> |
| 40 | |
| 41 | #if defined(MBEDTLS_FS_IO) |
| 42 | #include <stdio.h> |
| 43 | #endif |
| 44 | |
| 45 | #if defined(MBEDTLS_ENTROPY_NV_SEED) |
| 46 | #include "mbedtls/platform.h" |
| 47 | #endif |
| 48 | |
| 49 | #if defined(MBEDTLS_SELF_TEST) |
| 50 | #if defined(MBEDTLS_PLATFORM_C) |
| 51 | #include "mbedtls/platform.h" |
| 52 | #else |
| 53 | #include <stdio.h> |
| 54 | #define mbedtls_printf printf |
| 55 | #endif /* MBEDTLS_PLATFORM_C */ |
| 56 | #endif /* MBEDTLS_SELF_TEST */ |
| 57 | |
| 58 | #if defined(MBEDTLS_HAVEGE_C) |
| 59 | #include "mbedtls/havege.h" |
| 60 | #endif |
| 61 | |
| 62 | /* Implementation that should never be optimized out by the compiler */ |
| 63 | static void mbedtls_zeroize( void *v, size_t n ) { |
| 64 | volatile unsigned char *p = v; while( n-- ) *p++ = 0; |
| 65 | } |
| 66 | |
| 67 | #define ENTROPY_MAX_LOOP 256 /**< Maximum amount to loop before error */ |
| 68 | |
| 69 | void mbedtls_entropy_init( mbedtls_entropy_context *ctx ) |
| 70 | { |
| 71 | memset( ctx, 0, sizeof(mbedtls_entropy_context) ); |
| 72 | |
| 73 | #if defined(MBEDTLS_THREADING_C) |
| 74 | mbedtls_mutex_init( &ctx->mutex ); |
| 75 | #endif |
| 76 | |
| 77 | #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR) |
| 78 | mbedtls_sha512_starts( &ctx->accumulator, 0 ); |
| 79 | #else |
| 80 | mbedtls_sha256_starts( &ctx->accumulator, 0 ); |
| 81 | #endif |
| 82 | #if defined(MBEDTLS_HAVEGE_C) |
| 83 | mbedtls_havege_init( &ctx->havege_data ); |
| 84 | #endif |
| 85 | |
| 86 | #if defined(MBEDTLS_TEST_NULL_ENTROPY) |
| 87 | mbedtls_entropy_add_source( ctx, mbedtls_null_entropy_poll, NULL, |
| 88 | 1, MBEDTLS_ENTROPY_SOURCE_STRONG ); |
| 89 | #endif |
| 90 | |
| 91 | #if !defined(MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES) |
| 92 | #if !defined(MBEDTLS_NO_PLATFORM_ENTROPY) |
| 93 | mbedtls_entropy_add_source( ctx, mbedtls_platform_entropy_poll, NULL, |
| 94 | MBEDTLS_ENTROPY_MIN_PLATFORM, |
| 95 | MBEDTLS_ENTROPY_SOURCE_STRONG ); |
| 96 | #endif |
| 97 | #if defined(MBEDTLS_TIMING_C) |
| 98 | mbedtls_entropy_add_source( ctx, mbedtls_hardclock_poll, NULL, |
| 99 | MBEDTLS_ENTROPY_MIN_HARDCLOCK, |
| 100 | MBEDTLS_ENTROPY_SOURCE_WEAK ); |
| 101 | #endif |
| 102 | #if defined(MBEDTLS_HAVEGE_C) |
| 103 | mbedtls_entropy_add_source( ctx, mbedtls_havege_poll, &ctx->havege_data, |
| 104 | MBEDTLS_ENTROPY_MIN_HAVEGE, |
| 105 | MBEDTLS_ENTROPY_SOURCE_STRONG ); |
| 106 | #endif |
| 107 | #if defined(MBEDTLS_ENTROPY_HARDWARE_ALT) |
| 108 | mbedtls_entropy_add_source( ctx, mbedtls_hardware_poll, NULL, |
| 109 | MBEDTLS_ENTROPY_MIN_HARDWARE, |
| 110 | MBEDTLS_ENTROPY_SOURCE_STRONG ); |
| 111 | #endif |
| 112 | #if defined(MBEDTLS_ENTROPY_NV_SEED) |
| 113 | mbedtls_entropy_add_source( ctx, mbedtls_nv_seed_poll, NULL, |
| 114 | MBEDTLS_ENTROPY_BLOCK_SIZE, |
| 115 | MBEDTLS_ENTROPY_SOURCE_STRONG ); |
| 116 | #endif |
| 117 | #endif /* MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES */ |
| 118 | } |
| 119 | |
| 120 | void mbedtls_entropy_free( mbedtls_entropy_context *ctx ) |
| 121 | { |
| 122 | #if defined(MBEDTLS_HAVEGE_C) |
| 123 | mbedtls_havege_free( &ctx->havege_data ); |
| 124 | #endif |
| 125 | #if defined(MBEDTLS_THREADING_C) |
| 126 | mbedtls_mutex_free( &ctx->mutex ); |
| 127 | #endif |
| 128 | mbedtls_zeroize( ctx, sizeof( mbedtls_entropy_context ) ); |
| 129 | } |
| 130 | |
| 131 | int mbedtls_entropy_add_source( mbedtls_entropy_context *ctx, |
| 132 | mbedtls_entropy_f_source_ptr f_source, void *p_source, |
| 133 | size_t threshold, int strong ) |
| 134 | { |
| 135 | int idx, ret = 0; |
| 136 | |
| 137 | #if defined(MBEDTLS_THREADING_C) |
| 138 | if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) |
| 139 | return( ret ); |
| 140 | #endif |
| 141 | |
| 142 | idx = ctx->source_count; |
| 143 | if( idx >= MBEDTLS_ENTROPY_MAX_SOURCES ) |
| 144 | { |
| 145 | ret = MBEDTLS_ERR_ENTROPY_MAX_SOURCES; |
| 146 | goto exit; |
| 147 | } |
| 148 | |
| 149 | ctx->source[idx].f_source = f_source; |
| 150 | ctx->source[idx].p_source = p_source; |
| 151 | ctx->source[idx].threshold = threshold; |
| 152 | ctx->source[idx].strong = strong; |
| 153 | |
| 154 | ctx->source_count++; |
| 155 | |
| 156 | exit: |
| 157 | #if defined(MBEDTLS_THREADING_C) |
| 158 | if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) |
| 159 | return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); |
| 160 | #endif |
| 161 | |
| 162 | return( ret ); |
| 163 | } |
| 164 | |
| 165 | /* |
| 166 | * Entropy accumulator update |
| 167 | */ |
| 168 | static int entropy_update( mbedtls_entropy_context *ctx, unsigned char source_id, |
| 169 | const unsigned char *data, size_t len ) |
| 170 | { |
| 171 | unsigned char header[2]; |
| 172 | unsigned char tmp[MBEDTLS_ENTROPY_BLOCK_SIZE]; |
| 173 | size_t use_len = len; |
| 174 | const unsigned char *p = data; |
| 175 | |
| 176 | if( use_len > MBEDTLS_ENTROPY_BLOCK_SIZE ) |
| 177 | { |
| 178 | #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR) |
| 179 | mbedtls_sha512( data, len, tmp, 0 ); |
| 180 | #else |
| 181 | mbedtls_sha256( data, len, tmp, 0 ); |
| 182 | #endif |
| 183 | p = tmp; |
| 184 | use_len = MBEDTLS_ENTROPY_BLOCK_SIZE; |
| 185 | } |
| 186 | |
| 187 | header[0] = source_id; |
| 188 | header[1] = use_len & 0xFF; |
| 189 | |
| 190 | #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR) |
| 191 | mbedtls_sha512_update( &ctx->accumulator, header, 2 ); |
| 192 | mbedtls_sha512_update( &ctx->accumulator, p, use_len ); |
| 193 | #else |
| 194 | mbedtls_sha256_update( &ctx->accumulator, header, 2 ); |
| 195 | mbedtls_sha256_update( &ctx->accumulator, p, use_len ); |
| 196 | #endif |
| 197 | |
| 198 | return( 0 ); |
| 199 | } |
| 200 | |
| 201 | int mbedtls_entropy_update_manual( mbedtls_entropy_context *ctx, |
| 202 | const unsigned char *data, size_t len ) |
| 203 | { |
| 204 | int ret; |
| 205 | |
| 206 | #if defined(MBEDTLS_THREADING_C) |
| 207 | if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) |
| 208 | return( ret ); |
| 209 | #endif |
| 210 | |
| 211 | ret = entropy_update( ctx, MBEDTLS_ENTROPY_SOURCE_MANUAL, data, len ); |
| 212 | |
| 213 | #if defined(MBEDTLS_THREADING_C) |
| 214 | if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) |
| 215 | return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); |
| 216 | #endif |
| 217 | |
| 218 | return( ret ); |
| 219 | } |
| 220 | |
| 221 | /* |
| 222 | * Run through the different sources to add entropy to our accumulator |
| 223 | */ |
| 224 | static int entropy_gather_internal( mbedtls_entropy_context *ctx ) |
| 225 | { |
| 226 | int ret, i, have_one_strong = 0; |
| 227 | unsigned char buf[MBEDTLS_ENTROPY_MAX_GATHER]; |
| 228 | size_t olen; |
| 229 | |
| 230 | if( ctx->source_count == 0 ) |
| 231 | return( MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED ); |
| 232 | |
| 233 | /* |
| 234 | * Run through our entropy sources |
| 235 | */ |
| 236 | for( i = 0; i < ctx->source_count; i++ ) |
| 237 | { |
| 238 | if( ctx->source[i].strong == MBEDTLS_ENTROPY_SOURCE_STRONG ) |
| 239 | have_one_strong = 1; |
| 240 | |
| 241 | olen = 0; |
| 242 | if( ( ret = ctx->source[i].f_source( ctx->source[i].p_source, |
| 243 | buf, MBEDTLS_ENTROPY_MAX_GATHER, &olen ) ) != 0 ) |
| 244 | { |
| 245 | return( ret ); |
| 246 | } |
| 247 | |
| 248 | /* |
| 249 | * Add if we actually gathered something |
| 250 | */ |
| 251 | if( olen > 0 ) |
| 252 | { |
| 253 | entropy_update( ctx, (unsigned char) i, buf, olen ); |
| 254 | ctx->source[i].size += olen; |
| 255 | } |
| 256 | } |
| 257 | |
| 258 | if( have_one_strong == 0 ) |
| 259 | return( MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE ); |
| 260 | |
| 261 | return( 0 ); |
| 262 | } |
| 263 | |
| 264 | /* |
| 265 | * Thread-safe wrapper for entropy_gather_internal() |
| 266 | */ |
| 267 | int mbedtls_entropy_gather( mbedtls_entropy_context *ctx ) |
| 268 | { |
| 269 | int ret; |
| 270 | |
| 271 | #if defined(MBEDTLS_THREADING_C) |
| 272 | if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) |
| 273 | return( ret ); |
| 274 | #endif |
| 275 | |
| 276 | ret = entropy_gather_internal( ctx ); |
| 277 | |
| 278 | #if defined(MBEDTLS_THREADING_C) |
| 279 | if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) |
| 280 | return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); |
| 281 | #endif |
| 282 | |
| 283 | return( ret ); |
| 284 | } |
| 285 | |
| 286 | int mbedtls_entropy_func( void *data, unsigned char *output, size_t len ) |
| 287 | { |
| 288 | int ret, count = 0, i, done; |
| 289 | mbedtls_entropy_context *ctx = (mbedtls_entropy_context *) data; |
| 290 | unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE]; |
| 291 | |
| 292 | if( len > MBEDTLS_ENTROPY_BLOCK_SIZE ) |
| 293 | return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); |
| 294 | |
| 295 | #if defined(MBEDTLS_ENTROPY_NV_SEED) |
| 296 | /* Update the NV entropy seed before generating any entropy for outside |
| 297 | * use. |
| 298 | */ |
| 299 | if( ctx->initial_entropy_run == 0 ) |
| 300 | { |
| 301 | ctx->initial_entropy_run = 1; |
| 302 | if( ( ret = mbedtls_entropy_update_nv_seed( ctx ) ) != 0 ) |
| 303 | return( ret ); |
| 304 | } |
| 305 | #endif |
| 306 | |
| 307 | #if defined(MBEDTLS_THREADING_C) |
| 308 | if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) |
| 309 | return( ret ); |
| 310 | #endif |
| 311 | |
| 312 | /* |
| 313 | * Always gather extra entropy before a call |
| 314 | */ |
| 315 | do |
| 316 | { |
| 317 | if( count++ > ENTROPY_MAX_LOOP ) |
| 318 | { |
| 319 | ret = MBEDTLS_ERR_ENTROPY_SOURCE_FAILED; |
| 320 | goto exit; |
| 321 | } |
| 322 | |
| 323 | if( ( ret = entropy_gather_internal( ctx ) ) != 0 ) |
| 324 | goto exit; |
| 325 | |
| 326 | done = 1; |
| 327 | for( i = 0; i < ctx->source_count; i++ ) |
| 328 | if( ctx->source[i].size < ctx->source[i].threshold ) |
| 329 | done = 0; |
| 330 | } |
| 331 | while( ! done ); |
| 332 | |
| 333 | memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE ); |
| 334 | |
| 335 | #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR) |
| 336 | mbedtls_sha512_finish( &ctx->accumulator, buf ); |
| 337 | |
| 338 | /* |
| 339 | * Reset accumulator and counters and recycle existing entropy |
| 340 | */ |
| 341 | memset( &ctx->accumulator, 0, sizeof( mbedtls_sha512_context ) ); |
| 342 | mbedtls_sha512_starts( &ctx->accumulator, 0 ); |
| 343 | mbedtls_sha512_update( &ctx->accumulator, buf, MBEDTLS_ENTROPY_BLOCK_SIZE ); |
| 344 | |
| 345 | /* |
| 346 | * Perform second SHA-512 on entropy |
| 347 | */ |
| 348 | mbedtls_sha512( buf, MBEDTLS_ENTROPY_BLOCK_SIZE, buf, 0 ); |
| 349 | #else /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */ |
| 350 | mbedtls_sha256_finish( &ctx->accumulator, buf ); |
| 351 | |
| 352 | /* |
| 353 | * Reset accumulator and counters and recycle existing entropy |
| 354 | */ |
| 355 | memset( &ctx->accumulator, 0, sizeof( mbedtls_sha256_context ) ); |
| 356 | mbedtls_sha256_starts( &ctx->accumulator, 0 ); |
| 357 | mbedtls_sha256_update( &ctx->accumulator, buf, MBEDTLS_ENTROPY_BLOCK_SIZE ); |
| 358 | |
| 359 | /* |
| 360 | * Perform second SHA-256 on entropy |
| 361 | */ |
| 362 | mbedtls_sha256( buf, MBEDTLS_ENTROPY_BLOCK_SIZE, buf, 0 ); |
| 363 | #endif /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */ |
| 364 | |
| 365 | for( i = 0; i < ctx->source_count; i++ ) |
| 366 | ctx->source[i].size = 0; |
| 367 | |
| 368 | memcpy( output, buf, len ); |
| 369 | |
| 370 | ret = 0; |
| 371 | |
| 372 | exit: |
| 373 | #if defined(MBEDTLS_THREADING_C) |
| 374 | if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) |
| 375 | return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); |
| 376 | #endif |
| 377 | |
| 378 | return( ret ); |
| 379 | } |
| 380 | |
| 381 | #if defined(MBEDTLS_ENTROPY_NV_SEED) |
| 382 | int mbedtls_entropy_update_nv_seed( mbedtls_entropy_context *ctx ) |
| 383 | { |
| 384 | int ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR; |
| 385 | unsigned char buf[ MBEDTLS_ENTROPY_MAX_SEED_SIZE ]; |
| 386 | |
| 387 | /* Read new seed and write it to NV */ |
| 388 | if( ( ret = mbedtls_entropy_func( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 ) |
| 389 | return( ret ); |
| 390 | |
| 391 | if( mbedtls_nv_seed_write( buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) < 0 ) |
| 392 | return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR ); |
| 393 | |
| 394 | /* Manually update the remaining stream with a separator value to diverge */ |
| 395 | memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE ); |
| 396 | mbedtls_entropy_update_manual( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE ); |
| 397 | |
| 398 | return( 0 ); |
| 399 | } |
| 400 | #endif /* MBEDTLS_ENTROPY_NV_SEED */ |
| 401 | |
| 402 | #if defined(MBEDTLS_FS_IO) |
| 403 | int mbedtls_entropy_write_seed_file( mbedtls_entropy_context *ctx, const char *path ) |
| 404 | { |
| 405 | int ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR; |
| 406 | FILE *f; |
| 407 | unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE]; |
| 408 | |
| 409 | if( ( f = fopen( path, "wb" ) ) == NULL ) |
| 410 | return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR ); |
| 411 | |
| 412 | if( ( ret = mbedtls_entropy_func( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 ) |
| 413 | goto exit; |
| 414 | |
| 415 | if( fwrite( buf, 1, MBEDTLS_ENTROPY_BLOCK_SIZE, f ) != MBEDTLS_ENTROPY_BLOCK_SIZE ) |
| 416 | { |
| 417 | ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR; |
| 418 | goto exit; |
| 419 | } |
| 420 | |
| 421 | ret = 0; |
| 422 | |
| 423 | exit: |
| 424 | fclose( f ); |
| 425 | return( ret ); |
| 426 | } |
| 427 | |
| 428 | int mbedtls_entropy_update_seed_file( mbedtls_entropy_context *ctx, const char *path ) |
| 429 | { |
| 430 | FILE *f; |
| 431 | size_t n; |
| 432 | unsigned char buf[ MBEDTLS_ENTROPY_MAX_SEED_SIZE ]; |
| 433 | |
| 434 | if( ( f = fopen( path, "rb" ) ) == NULL ) |
| 435 | return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR ); |
| 436 | |
| 437 | fseek( f, 0, SEEK_END ); |
| 438 | n = (size_t) ftell( f ); |
| 439 | fseek( f, 0, SEEK_SET ); |
| 440 | |
| 441 | if( n > MBEDTLS_ENTROPY_MAX_SEED_SIZE ) |
| 442 | n = MBEDTLS_ENTROPY_MAX_SEED_SIZE; |
| 443 | |
| 444 | if( fread( buf, 1, n, f ) != n ) |
| 445 | { |
| 446 | fclose( f ); |
| 447 | return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR ); |
| 448 | } |
| 449 | |
| 450 | fclose( f ); |
| 451 | |
| 452 | mbedtls_entropy_update_manual( ctx, buf, n ); |
| 453 | |
| 454 | return( mbedtls_entropy_write_seed_file( ctx, path ) ); |
| 455 | } |
| 456 | #endif /* MBEDTLS_FS_IO */ |
| 457 | |
| 458 | #if defined(MBEDTLS_SELF_TEST) |
| 459 | #if !defined(MBEDTLS_TEST_NULL_ENTROPY) |
| 460 | /* |
| 461 | * Dummy source function |
| 462 | */ |
| 463 | static int entropy_dummy_source( void *data, unsigned char *output, |
| 464 | size_t len, size_t *olen ) |
| 465 | { |
| 466 | ((void) data); |
| 467 | |
| 468 | memset( output, 0x2a, len ); |
| 469 | *olen = len; |
| 470 | |
| 471 | return( 0 ); |
| 472 | } |
| 473 | #endif /* !MBEDTLS_TEST_NULL_ENTROPY */ |
| 474 | |
| 475 | #if defined(MBEDTLS_ENTROPY_HARDWARE_ALT) |
| 476 | |
| 477 | static int mbedtls_entropy_source_self_test_gather( unsigned char *buf, size_t buf_len ) |
| 478 | { |
| 479 | int ret = 0; |
| 480 | size_t entropy_len = 0; |
| 481 | size_t olen = 0; |
| 482 | size_t attempts = buf_len; |
| 483 | |
| 484 | while( attempts > 0 && entropy_len < buf_len ) |
| 485 | { |
| 486 | if( ( ret = mbedtls_hardware_poll( NULL, buf + entropy_len, |
| 487 | buf_len - entropy_len, &olen ) ) != 0 ) |
| 488 | return( ret ); |
| 489 | |
| 490 | entropy_len += olen; |
| 491 | attempts--; |
| 492 | } |
| 493 | |
| 494 | if( entropy_len < buf_len ) |
| 495 | { |
| 496 | ret = 1; |
| 497 | } |
| 498 | |
| 499 | return( ret ); |
| 500 | } |
| 501 | |
| 502 | |
| 503 | static int mbedtls_entropy_source_self_test_check_bits( const unsigned char *buf, |
| 504 | size_t buf_len ) |
| 505 | { |
| 506 | unsigned char set= 0xFF; |
| 507 | unsigned char unset = 0x00; |
| 508 | size_t i; |
| 509 | |
| 510 | for( i = 0; i < buf_len; i++ ) |
| 511 | { |
| 512 | set &= buf[i]; |
| 513 | unset |= buf[i]; |
| 514 | } |
| 515 | |
| 516 | return( set == 0xFF || unset == 0x00 ); |
| 517 | } |
| 518 | |
| 519 | /* |
| 520 | * A test to ensure hat the entropy sources are functioning correctly |
| 521 | * and there is no obvious failure. The test performs the following checks: |
| 522 | * - The entropy source is not providing only 0s (all bits unset) or 1s (all |
| 523 | * bits set). |
| 524 | * - The entropy source is not providing values in a pattern. Because the |
| 525 | * hardware could be providing data in an arbitrary length, this check polls |
| 526 | * the hardware entropy source twice and compares the result to ensure they |
| 527 | * are not equal. |
| 528 | * - The error code returned by the entropy source is not an error. |
| 529 | */ |
| 530 | int mbedtls_entropy_source_self_test( int verbose ) |
| 531 | { |
| 532 | int ret = 0; |
| 533 | unsigned char buf0[2 * sizeof( unsigned long long int )]; |
| 534 | unsigned char buf1[2 * sizeof( unsigned long long int )]; |
| 535 | |
| 536 | if( verbose != 0 ) |
| 537 | mbedtls_printf( " ENTROPY_BIAS test: " ); |
| 538 | |
| 539 | memset( buf0, 0x00, sizeof( buf0 ) ); |
| 540 | memset( buf1, 0x00, sizeof( buf1 ) ); |
| 541 | |
| 542 | if( ( ret = mbedtls_entropy_source_self_test_gather( buf0, sizeof( buf0 ) ) ) != 0 ) |
| 543 | goto cleanup; |
| 544 | if( ( ret = mbedtls_entropy_source_self_test_gather( buf1, sizeof( buf1 ) ) ) != 0 ) |
| 545 | goto cleanup; |
| 546 | |
| 547 | /* Make sure that the returned values are not all 0 or 1 */ |
| 548 | if( ( ret = mbedtls_entropy_source_self_test_check_bits( buf0, sizeof( buf0 ) ) ) != 0 ) |
| 549 | goto cleanup; |
| 550 | if( ( ret = mbedtls_entropy_source_self_test_check_bits( buf1, sizeof( buf1 ) ) ) != 0 ) |
| 551 | goto cleanup; |
| 552 | |
| 553 | /* Make sure that the entropy source is not returning values in a |
| 554 | * pattern */ |
| 555 | ret = memcmp( buf0, buf1, sizeof( buf0 ) ) == 0; |
| 556 | |
| 557 | cleanup: |
| 558 | if( verbose != 0 ) |
| 559 | { |
| 560 | if( ret != 0 ) |
| 561 | mbedtls_printf( "failed\n" ); |
| 562 | else |
| 563 | mbedtls_printf( "passed\n" ); |
| 564 | |
| 565 | mbedtls_printf( "\n" ); |
| 566 | } |
| 567 | |
| 568 | return( ret != 0 ); |
| 569 | } |
| 570 | |
| 571 | #endif /* MBEDTLS_ENTROPY_HARDWARE_ALT */ |
| 572 | |
| 573 | /* |
| 574 | * The actual entropy quality is hard to test, but we can at least |
| 575 | * test that the functions don't cause errors and write the correct |
| 576 | * amount of data to buffers. |
| 577 | */ |
| 578 | int mbedtls_entropy_self_test( int verbose ) |
| 579 | { |
| 580 | int ret = 1; |
| 581 | #if !defined(MBEDTLS_TEST_NULL_ENTROPY) |
| 582 | mbedtls_entropy_context ctx; |
| 583 | unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 }; |
| 584 | unsigned char acc[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 }; |
| 585 | size_t i, j; |
| 586 | #endif /* !MBEDTLS_TEST_NULL_ENTROPY */ |
| 587 | |
| 588 | if( verbose != 0 ) |
| 589 | mbedtls_printf( " ENTROPY test: " ); |
| 590 | |
| 591 | #if !defined(MBEDTLS_TEST_NULL_ENTROPY) |
| 592 | mbedtls_entropy_init( &ctx ); |
| 593 | |
| 594 | /* First do a gather to make sure we have default sources */ |
| 595 | if( ( ret = mbedtls_entropy_gather( &ctx ) ) != 0 ) |
| 596 | goto cleanup; |
| 597 | |
| 598 | ret = mbedtls_entropy_add_source( &ctx, entropy_dummy_source, NULL, 16, |
| 599 | MBEDTLS_ENTROPY_SOURCE_WEAK ); |
| 600 | if( ret != 0 ) |
| 601 | goto cleanup; |
| 602 | |
| 603 | if( ( ret = mbedtls_entropy_update_manual( &ctx, buf, sizeof buf ) ) != 0 ) |
| 604 | goto cleanup; |
| 605 | |
| 606 | /* |
| 607 | * To test that mbedtls_entropy_func writes correct number of bytes: |
| 608 | * - use the whole buffer and rely on ASan to detect overruns |
| 609 | * - collect entropy 8 times and OR the result in an accumulator: |
| 610 | * any byte should then be 0 with probably 2^(-64), so requiring |
| 611 | * each of the 32 or 64 bytes to be non-zero has a false failure rate |
| 612 | * of at most 2^(-58) which is acceptable. |
| 613 | */ |
| 614 | for( i = 0; i < 8; i++ ) |
| 615 | { |
| 616 | if( ( ret = mbedtls_entropy_func( &ctx, buf, sizeof( buf ) ) ) != 0 ) |
| 617 | goto cleanup; |
| 618 | |
| 619 | for( j = 0; j < sizeof( buf ); j++ ) |
| 620 | acc[j] |= buf[j]; |
| 621 | } |
| 622 | |
| 623 | for( j = 0; j < sizeof( buf ); j++ ) |
| 624 | { |
| 625 | if( acc[j] == 0 ) |
| 626 | { |
| 627 | ret = 1; |
| 628 | goto cleanup; |
| 629 | } |
| 630 | } |
| 631 | |
| 632 | #if defined(MBEDTLS_ENTROPY_HARDWARE_ALT) |
| 633 | if( ( ret = mbedtls_entropy_source_self_test( 0 ) ) != 0 ) |
| 634 | goto cleanup; |
| 635 | #endif |
| 636 | |
| 637 | cleanup: |
| 638 | mbedtls_entropy_free( &ctx ); |
| 639 | #endif /* !MBEDTLS_TEST_NULL_ENTROPY */ |
| 640 | |
| 641 | if( verbose != 0 ) |
| 642 | { |
| 643 | if( ret != 0 ) |
| 644 | mbedtls_printf( "failed\n" ); |
| 645 | else |
| 646 | mbedtls_printf( "passed\n" ); |
| 647 | |
| 648 | mbedtls_printf( "\n" ); |
| 649 | } |
| 650 | |
| 651 | return( ret != 0 ); |
| 652 | } |
| 653 | #endif /* MBEDTLS_SELF_TEST */ |
| 654 | |
| 655 | #endif /* MBEDTLS_ENTROPY_C */ |