1 /* 2 * DRBG: Deterministic Random Bits Generator 3 * Based on NIST Recommended DRBG from NIST SP800-90A with the following 4 * properties: 5 * * CTR DRBG with DF with AES-128, AES-192, AES-256 cores 6 * * Hash DRBG with DF with SHA-1, SHA-256, SHA-384, SHA-512 cores 7 * * HMAC DRBG with DF with SHA-1, SHA-256, SHA-384, SHA-512 cores 8 * * with and without prediction resistance 9 * 10 * Copyright Stephan Mueller <smueller@chronox.de>, 2014 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, and the entire permission notice in its entirety, 17 * including the disclaimer of warranties. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. The name of the author may not be used to endorse or promote 22 * products derived from this software without specific prior 23 * written permission. 24 * 25 * ALTERNATIVELY, this product may be distributed under the terms of 26 * the GNU General Public License, in which case the provisions of the GPL are 27 * required INSTEAD OF the above restrictions. (This clause is 28 * necessary due to a potential bad interaction between the GPL and 29 * the restrictions contained in a BSD-style copyright.) 30 * 31 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED 32 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 33 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF 34 * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE 35 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 36 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 37 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR 38 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 39 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 40 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE 41 * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH 42 * DAMAGE. 43 * 44 * DRBG Usage 45 * ========== 46 * The SP 800-90A DRBG allows the user to specify a personalization string 47 * for initialization as well as an additional information string for each 48 * random number request. The following code fragments show how a caller 49 * uses the kernel crypto API to use the full functionality of the DRBG. 50 * 51 * Usage without any additional data 52 * --------------------------------- 53 * struct crypto_rng *drng; 54 * int err; 55 * char data[DATALEN]; 56 * 57 * drng = crypto_alloc_rng(drng_name, 0, 0); 58 * err = crypto_rng_get_bytes(drng, &data, DATALEN); 59 * crypto_free_rng(drng); 60 * 61 * 62 * Usage with personalization string during initialization 63 * ------------------------------------------------------- 64 * struct crypto_rng *drng; 65 * int err; 66 * char data[DATALEN]; 67 * struct drbg_string pers; 68 * char personalization[11] = "some-string"; 69 * 70 * drbg_string_fill(&pers, personalization, strlen(personalization)); 71 * drng = crypto_alloc_rng(drng_name, 0, 0); 72 * // The reset completely re-initializes the DRBG with the provided 73 * // personalization string 74 * err = crypto_rng_reset(drng, &personalization, strlen(personalization)); 75 * err = crypto_rng_get_bytes(drng, &data, DATALEN); 76 * crypto_free_rng(drng); 77 * 78 * 79 * Usage with additional information string during random number request 80 * --------------------------------------------------------------------- 81 * struct crypto_rng *drng; 82 * int err; 83 * char data[DATALEN]; 84 * char addtl_string[11] = "some-string"; 85 * string drbg_string addtl; 86 * 87 * drbg_string_fill(&addtl, addtl_string, strlen(addtl_string)); 88 * drng = crypto_alloc_rng(drng_name, 0, 0); 89 * // The following call is a wrapper to crypto_rng_get_bytes() and returns 90 * // the same error codes. 91 * err = crypto_drbg_get_bytes_addtl(drng, &data, DATALEN, &addtl); 92 * crypto_free_rng(drng); 93 * 94 * 95 * Usage with personalization and additional information strings 96 * ------------------------------------------------------------- 97 * Just mix both scenarios above. 98 */ 99 100 #include <crypto/drbg.h> 101 #include <linux/kernel.h> 102 103 /*************************************************************** 104 * Backend cipher definitions available to DRBG 105 ***************************************************************/ 106 107 /* 108 * The order of the DRBG definitions here matter: every DRBG is registered 109 * as stdrng. Each DRBG receives an increasing cra_priority values the later 110 * they are defined in this array (see drbg_fill_array). 111 * 112 * HMAC DRBGs are favored over Hash DRBGs over CTR DRBGs, and 113 * the SHA256 / AES 256 over other ciphers. Thus, the favored 114 * DRBGs are the latest entries in this array. 115 */ 116 static const struct drbg_core drbg_cores[] = { 117 #ifdef CONFIG_CRYPTO_DRBG_CTR 118 { 119 .flags = DRBG_CTR | DRBG_STRENGTH128, 120 .statelen = 32, /* 256 bits as defined in 10.2.1 */ 121 .blocklen_bytes = 16, 122 .cra_name = "ctr_aes128", 123 .backend_cra_name = "aes", 124 }, { 125 .flags = DRBG_CTR | DRBG_STRENGTH192, 126 .statelen = 40, /* 320 bits as defined in 10.2.1 */ 127 .blocklen_bytes = 16, 128 .cra_name = "ctr_aes192", 129 .backend_cra_name = "aes", 130 }, { 131 .flags = DRBG_CTR | DRBG_STRENGTH256, 132 .statelen = 48, /* 384 bits as defined in 10.2.1 */ 133 .blocklen_bytes = 16, 134 .cra_name = "ctr_aes256", 135 .backend_cra_name = "aes", 136 }, 137 #endif /* CONFIG_CRYPTO_DRBG_CTR */ 138 #ifdef CONFIG_CRYPTO_DRBG_HASH 139 { 140 .flags = DRBG_HASH | DRBG_STRENGTH128, 141 .statelen = 55, /* 440 bits */ 142 .blocklen_bytes = 20, 143 .cra_name = "sha1", 144 .backend_cra_name = "sha1", 145 }, { 146 .flags = DRBG_HASH | DRBG_STRENGTH256, 147 .statelen = 111, /* 888 bits */ 148 .blocklen_bytes = 48, 149 .cra_name = "sha384", 150 .backend_cra_name = "sha384", 151 }, { 152 .flags = DRBG_HASH | DRBG_STRENGTH256, 153 .statelen = 111, /* 888 bits */ 154 .blocklen_bytes = 64, 155 .cra_name = "sha512", 156 .backend_cra_name = "sha512", 157 }, { 158 .flags = DRBG_HASH | DRBG_STRENGTH256, 159 .statelen = 55, /* 440 bits */ 160 .blocklen_bytes = 32, 161 .cra_name = "sha256", 162 .backend_cra_name = "sha256", 163 }, 164 #endif /* CONFIG_CRYPTO_DRBG_HASH */ 165 #ifdef CONFIG_CRYPTO_DRBG_HMAC 166 { 167 .flags = DRBG_HMAC | DRBG_STRENGTH128, 168 .statelen = 20, /* block length of cipher */ 169 .blocklen_bytes = 20, 170 .cra_name = "hmac_sha1", 171 .backend_cra_name = "hmac(sha1)", 172 }, { 173 .flags = DRBG_HMAC | DRBG_STRENGTH256, 174 .statelen = 48, /* block length of cipher */ 175 .blocklen_bytes = 48, 176 .cra_name = "hmac_sha384", 177 .backend_cra_name = "hmac(sha384)", 178 }, { 179 .flags = DRBG_HMAC | DRBG_STRENGTH256, 180 .statelen = 64, /* block length of cipher */ 181 .blocklen_bytes = 64, 182 .cra_name = "hmac_sha512", 183 .backend_cra_name = "hmac(sha512)", 184 }, { 185 .flags = DRBG_HMAC | DRBG_STRENGTH256, 186 .statelen = 32, /* block length of cipher */ 187 .blocklen_bytes = 32, 188 .cra_name = "hmac_sha256", 189 .backend_cra_name = "hmac(sha256)", 190 }, 191 #endif /* CONFIG_CRYPTO_DRBG_HMAC */ 192 }; 193 194 static int drbg_uninstantiate(struct drbg_state *drbg); 195 196 /****************************************************************** 197 * Generic helper functions 198 ******************************************************************/ 199 200 /* 201 * Return strength of DRBG according to SP800-90A section 8.4 202 * 203 * @flags DRBG flags reference 204 * 205 * Return: normalized strength in *bytes* value or 32 as default 206 * to counter programming errors 207 */ 208 static inline unsigned short drbg_sec_strength(drbg_flag_t flags) 209 { 210 switch (flags & DRBG_STRENGTH_MASK) { 211 case DRBG_STRENGTH128: 212 return 16; 213 case DRBG_STRENGTH192: 214 return 24; 215 case DRBG_STRENGTH256: 216 return 32; 217 default: 218 return 32; 219 } 220 } 221 222 /* 223 * FIPS 140-2 continuous self test for the noise source 224 * The test is performed on the noise source input data. Thus, the function 225 * implicitly knows the size of the buffer to be equal to the security 226 * strength. 227 * 228 * Note, this function disregards the nonce trailing the entropy data during 229 * initial seeding. 230 * 231 * drbg->drbg_mutex must have been taken. 232 * 233 * @drbg DRBG handle 234 * @entropy buffer of seed data to be checked 235 * 236 * return: 237 * 0 on success 238 * -EAGAIN on when the CTRNG is not yet primed 239 * < 0 on error 240 */ 241 static int drbg_fips_continuous_test(struct drbg_state *drbg, 242 const unsigned char *entropy) 243 { 244 unsigned short entropylen = drbg_sec_strength(drbg->core->flags); 245 int ret = 0; 246 247 if (!IS_ENABLED(CONFIG_CRYPTO_FIPS)) 248 return 0; 249 250 /* skip test if we test the overall system */ 251 if (list_empty(&drbg->test_data.list)) 252 return 0; 253 /* only perform test in FIPS mode */ 254 if (!fips_enabled) 255 return 0; 256 257 if (!drbg->fips_primed) { 258 /* Priming of FIPS test */ 259 memcpy(drbg->prev, entropy, entropylen); 260 drbg->fips_primed = true; 261 /* priming: another round is needed */ 262 return -EAGAIN; 263 } 264 ret = memcmp(drbg->prev, entropy, entropylen); 265 if (!ret) 266 panic("DRBG continuous self test failed\n"); 267 memcpy(drbg->prev, entropy, entropylen); 268 269 /* the test shall pass when the two values are not equal */ 270 return 0; 271 } 272 273 /* 274 * Convert an integer into a byte representation of this integer. 275 * The byte representation is big-endian 276 * 277 * @val value to be converted 278 * @buf buffer holding the converted integer -- caller must ensure that 279 * buffer size is at least 32 bit 280 */ 281 #if (defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR)) 282 static inline void drbg_cpu_to_be32(__u32 val, unsigned char *buf) 283 { 284 struct s { 285 __be32 conv; 286 }; 287 struct s *conversion = (struct s *) buf; 288 289 conversion->conv = cpu_to_be32(val); 290 } 291 #endif /* defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR) */ 292 293 /****************************************************************** 294 * CTR DRBG callback functions 295 ******************************************************************/ 296 297 #ifdef CONFIG_CRYPTO_DRBG_CTR 298 #define CRYPTO_DRBG_CTR_STRING "CTR " 299 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes256"); 300 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes256"); 301 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes192"); 302 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes192"); 303 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes128"); 304 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes128"); 305 306 static void drbg_kcapi_symsetkey(struct drbg_state *drbg, 307 const unsigned char *key); 308 static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval, 309 const struct drbg_string *in); 310 static int drbg_init_sym_kernel(struct drbg_state *drbg); 311 static int drbg_fini_sym_kernel(struct drbg_state *drbg); 312 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg, 313 u8 *inbuf, u32 inbuflen, 314 u8 *outbuf, u32 outlen); 315 #define DRBG_OUTSCRATCHLEN 256 316 317 /* BCC function for CTR DRBG as defined in 10.4.3 */ 318 static int drbg_ctr_bcc(struct drbg_state *drbg, 319 unsigned char *out, const unsigned char *key, 320 struct list_head *in) 321 { 322 int ret = 0; 323 struct drbg_string *curr = NULL; 324 struct drbg_string data; 325 short cnt = 0; 326 327 drbg_string_fill(&data, out, drbg_blocklen(drbg)); 328 329 /* 10.4.3 step 2 / 4 */ 330 drbg_kcapi_symsetkey(drbg, key); 331 list_for_each_entry(curr, in, list) { 332 const unsigned char *pos = curr->buf; 333 size_t len = curr->len; 334 /* 10.4.3 step 4.1 */ 335 while (len) { 336 /* 10.4.3 step 4.2 */ 337 if (drbg_blocklen(drbg) == cnt) { 338 cnt = 0; 339 ret = drbg_kcapi_sym(drbg, out, &data); 340 if (ret) 341 return ret; 342 } 343 out[cnt] ^= *pos; 344 pos++; 345 cnt++; 346 len--; 347 } 348 } 349 /* 10.4.3 step 4.2 for last block */ 350 if (cnt) 351 ret = drbg_kcapi_sym(drbg, out, &data); 352 353 return ret; 354 } 355 356 /* 357 * scratchpad usage: drbg_ctr_update is interlinked with drbg_ctr_df 358 * (and drbg_ctr_bcc, but this function does not need any temporary buffers), 359 * the scratchpad is used as follows: 360 * drbg_ctr_update: 361 * temp 362 * start: drbg->scratchpad 363 * length: drbg_statelen(drbg) + drbg_blocklen(drbg) 364 * note: the cipher writing into this variable works 365 * blocklen-wise. Now, when the statelen is not a multiple 366 * of blocklen, the generateion loop below "spills over" 367 * by at most blocklen. Thus, we need to give sufficient 368 * memory. 369 * df_data 370 * start: drbg->scratchpad + 371 * drbg_statelen(drbg) + drbg_blocklen(drbg) 372 * length: drbg_statelen(drbg) 373 * 374 * drbg_ctr_df: 375 * pad 376 * start: df_data + drbg_statelen(drbg) 377 * length: drbg_blocklen(drbg) 378 * iv 379 * start: pad + drbg_blocklen(drbg) 380 * length: drbg_blocklen(drbg) 381 * temp 382 * start: iv + drbg_blocklen(drbg) 383 * length: drbg_satelen(drbg) + drbg_blocklen(drbg) 384 * note: temp is the buffer that the BCC function operates 385 * on. BCC operates blockwise. drbg_statelen(drbg) 386 * is sufficient when the DRBG state length is a multiple 387 * of the block size. For AES192 (and maybe other ciphers) 388 * this is not correct and the length for temp is 389 * insufficient (yes, that also means for such ciphers, 390 * the final output of all BCC rounds are truncated). 391 * Therefore, add drbg_blocklen(drbg) to cover all 392 * possibilities. 393 */ 394 395 /* Derivation Function for CTR DRBG as defined in 10.4.2 */ 396 static int drbg_ctr_df(struct drbg_state *drbg, 397 unsigned char *df_data, size_t bytes_to_return, 398 struct list_head *seedlist) 399 { 400 int ret = -EFAULT; 401 unsigned char L_N[8]; 402 /* S3 is input */ 403 struct drbg_string S1, S2, S4, cipherin; 404 LIST_HEAD(bcc_list); 405 unsigned char *pad = df_data + drbg_statelen(drbg); 406 unsigned char *iv = pad + drbg_blocklen(drbg); 407 unsigned char *temp = iv + drbg_blocklen(drbg); 408 size_t padlen = 0; 409 unsigned int templen = 0; 410 /* 10.4.2 step 7 */ 411 unsigned int i = 0; 412 /* 10.4.2 step 8 */ 413 const unsigned char *K = (unsigned char *) 414 "\x00\x01\x02\x03\x04\x05\x06\x07" 415 "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f" 416 "\x10\x11\x12\x13\x14\x15\x16\x17" 417 "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f"; 418 unsigned char *X; 419 size_t generated_len = 0; 420 size_t inputlen = 0; 421 struct drbg_string *seed = NULL; 422 423 memset(pad, 0, drbg_blocklen(drbg)); 424 memset(iv, 0, drbg_blocklen(drbg)); 425 426 /* 10.4.2 step 1 is implicit as we work byte-wise */ 427 428 /* 10.4.2 step 2 */ 429 if ((512/8) < bytes_to_return) 430 return -EINVAL; 431 432 /* 10.4.2 step 2 -- calculate the entire length of all input data */ 433 list_for_each_entry(seed, seedlist, list) 434 inputlen += seed->len; 435 drbg_cpu_to_be32(inputlen, &L_N[0]); 436 437 /* 10.4.2 step 3 */ 438 drbg_cpu_to_be32(bytes_to_return, &L_N[4]); 439 440 /* 10.4.2 step 5: length is L_N, input_string, one byte, padding */ 441 padlen = (inputlen + sizeof(L_N) + 1) % (drbg_blocklen(drbg)); 442 /* wrap the padlen appropriately */ 443 if (padlen) 444 padlen = drbg_blocklen(drbg) - padlen; 445 /* 446 * pad / padlen contains the 0x80 byte and the following zero bytes. 447 * As the calculated padlen value only covers the number of zero 448 * bytes, this value has to be incremented by one for the 0x80 byte. 449 */ 450 padlen++; 451 pad[0] = 0x80; 452 453 /* 10.4.2 step 4 -- first fill the linked list and then order it */ 454 drbg_string_fill(&S1, iv, drbg_blocklen(drbg)); 455 list_add_tail(&S1.list, &bcc_list); 456 drbg_string_fill(&S2, L_N, sizeof(L_N)); 457 list_add_tail(&S2.list, &bcc_list); 458 list_splice_tail(seedlist, &bcc_list); 459 drbg_string_fill(&S4, pad, padlen); 460 list_add_tail(&S4.list, &bcc_list); 461 462 /* 10.4.2 step 9 */ 463 while (templen < (drbg_keylen(drbg) + (drbg_blocklen(drbg)))) { 464 /* 465 * 10.4.2 step 9.1 - the padding is implicit as the buffer 466 * holds zeros after allocation -- even the increment of i 467 * is irrelevant as the increment remains within length of i 468 */ 469 drbg_cpu_to_be32(i, iv); 470 /* 10.4.2 step 9.2 -- BCC and concatenation with temp */ 471 ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list); 472 if (ret) 473 goto out; 474 /* 10.4.2 step 9.3 */ 475 i++; 476 templen += drbg_blocklen(drbg); 477 } 478 479 /* 10.4.2 step 11 */ 480 X = temp + (drbg_keylen(drbg)); 481 drbg_string_fill(&cipherin, X, drbg_blocklen(drbg)); 482 483 /* 10.4.2 step 12: overwriting of outval is implemented in next step */ 484 485 /* 10.4.2 step 13 */ 486 drbg_kcapi_symsetkey(drbg, temp); 487 while (generated_len < bytes_to_return) { 488 short blocklen = 0; 489 /* 490 * 10.4.2 step 13.1: the truncation of the key length is 491 * implicit as the key is only drbg_blocklen in size based on 492 * the implementation of the cipher function callback 493 */ 494 ret = drbg_kcapi_sym(drbg, X, &cipherin); 495 if (ret) 496 goto out; 497 blocklen = (drbg_blocklen(drbg) < 498 (bytes_to_return - generated_len)) ? 499 drbg_blocklen(drbg) : 500 (bytes_to_return - generated_len); 501 /* 10.4.2 step 13.2 and 14 */ 502 memcpy(df_data + generated_len, X, blocklen); 503 generated_len += blocklen; 504 } 505 506 ret = 0; 507 508 out: 509 memset(iv, 0, drbg_blocklen(drbg)); 510 memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg)); 511 memset(pad, 0, drbg_blocklen(drbg)); 512 return ret; 513 } 514 515 /* 516 * update function of CTR DRBG as defined in 10.2.1.2 517 * 518 * The reseed variable has an enhanced meaning compared to the update 519 * functions of the other DRBGs as follows: 520 * 0 => initial seed from initialization 521 * 1 => reseed via drbg_seed 522 * 2 => first invocation from drbg_ctr_update when addtl is present. In 523 * this case, the df_data scratchpad is not deleted so that it is 524 * available for another calls to prevent calling the DF function 525 * again. 526 * 3 => second invocation from drbg_ctr_update. When the update function 527 * was called with addtl, the df_data memory already contains the 528 * DFed addtl information and we do not need to call DF again. 529 */ 530 static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed, 531 int reseed) 532 { 533 int ret = -EFAULT; 534 /* 10.2.1.2 step 1 */ 535 unsigned char *temp = drbg->scratchpad; 536 unsigned char *df_data = drbg->scratchpad + drbg_statelen(drbg) + 537 drbg_blocklen(drbg); 538 539 if (3 > reseed) 540 memset(df_data, 0, drbg_statelen(drbg)); 541 542 if (!reseed) { 543 /* 544 * The DRBG uses the CTR mode of the underlying AES cipher. The 545 * CTR mode increments the counter value after the AES operation 546 * but SP800-90A requires that the counter is incremented before 547 * the AES operation. Hence, we increment it at the time we set 548 * it by one. 549 */ 550 crypto_inc(drbg->V, drbg_blocklen(drbg)); 551 552 ret = crypto_skcipher_setkey(drbg->ctr_handle, drbg->C, 553 drbg_keylen(drbg)); 554 if (ret) 555 goto out; 556 } 557 558 /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */ 559 if (seed) { 560 ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg), seed); 561 if (ret) 562 goto out; 563 } 564 565 ret = drbg_kcapi_sym_ctr(drbg, df_data, drbg_statelen(drbg), 566 temp, drbg_statelen(drbg)); 567 if (ret) 568 return ret; 569 570 /* 10.2.1.2 step 5 */ 571 ret = crypto_skcipher_setkey(drbg->ctr_handle, temp, 572 drbg_keylen(drbg)); 573 if (ret) 574 goto out; 575 /* 10.2.1.2 step 6 */ 576 memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg)); 577 /* See above: increment counter by one to compensate timing of CTR op */ 578 crypto_inc(drbg->V, drbg_blocklen(drbg)); 579 ret = 0; 580 581 out: 582 memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg)); 583 if (2 != reseed) 584 memset(df_data, 0, drbg_statelen(drbg)); 585 return ret; 586 } 587 588 /* 589 * scratchpad use: drbg_ctr_update is called independently from 590 * drbg_ctr_extract_bytes. Therefore, the scratchpad is reused 591 */ 592 /* Generate function of CTR DRBG as defined in 10.2.1.5.2 */ 593 static int drbg_ctr_generate(struct drbg_state *drbg, 594 unsigned char *buf, unsigned int buflen, 595 struct list_head *addtl) 596 { 597 int ret; 598 int len = min_t(int, buflen, INT_MAX); 599 600 /* 10.2.1.5.2 step 2 */ 601 if (addtl && !list_empty(addtl)) { 602 ret = drbg_ctr_update(drbg, addtl, 2); 603 if (ret) 604 return 0; 605 } 606 607 /* 10.2.1.5.2 step 4.1 */ 608 ret = drbg_kcapi_sym_ctr(drbg, NULL, 0, buf, len); 609 if (ret) 610 return ret; 611 612 /* 10.2.1.5.2 step 6 */ 613 ret = drbg_ctr_update(drbg, NULL, 3); 614 if (ret) 615 len = ret; 616 617 return len; 618 } 619 620 static const struct drbg_state_ops drbg_ctr_ops = { 621 .update = drbg_ctr_update, 622 .generate = drbg_ctr_generate, 623 .crypto_init = drbg_init_sym_kernel, 624 .crypto_fini = drbg_fini_sym_kernel, 625 }; 626 #endif /* CONFIG_CRYPTO_DRBG_CTR */ 627 628 /****************************************************************** 629 * HMAC DRBG callback functions 630 ******************************************************************/ 631 632 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC) 633 static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval, 634 const struct list_head *in); 635 static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg, 636 const unsigned char *key); 637 static int drbg_init_hash_kernel(struct drbg_state *drbg); 638 static int drbg_fini_hash_kernel(struct drbg_state *drbg); 639 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */ 640 641 #ifdef CONFIG_CRYPTO_DRBG_HMAC 642 #define CRYPTO_DRBG_HMAC_STRING "HMAC " 643 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha512"); 644 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha512"); 645 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha384"); 646 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha384"); 647 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha256"); 648 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha256"); 649 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha1"); 650 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha1"); 651 652 /* update function of HMAC DRBG as defined in 10.1.2.2 */ 653 static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed, 654 int reseed) 655 { 656 int ret = -EFAULT; 657 int i = 0; 658 struct drbg_string seed1, seed2, vdata; 659 LIST_HEAD(seedlist); 660 LIST_HEAD(vdatalist); 661 662 if (!reseed) { 663 /* 10.1.2.3 step 2 -- memset(0) of C is implicit with kzalloc */ 664 memset(drbg->V, 1, drbg_statelen(drbg)); 665 drbg_kcapi_hmacsetkey(drbg, drbg->C); 666 } 667 668 drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg)); 669 list_add_tail(&seed1.list, &seedlist); 670 /* buffer of seed2 will be filled in for loop below with one byte */ 671 drbg_string_fill(&seed2, NULL, 1); 672 list_add_tail(&seed2.list, &seedlist); 673 /* input data of seed is allowed to be NULL at this point */ 674 if (seed) 675 list_splice_tail(seed, &seedlist); 676 677 drbg_string_fill(&vdata, drbg->V, drbg_statelen(drbg)); 678 list_add_tail(&vdata.list, &vdatalist); 679 for (i = 2; 0 < i; i--) { 680 /* first round uses 0x0, second 0x1 */ 681 unsigned char prefix = DRBG_PREFIX0; 682 if (1 == i) 683 prefix = DRBG_PREFIX1; 684 /* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */ 685 seed2.buf = &prefix; 686 ret = drbg_kcapi_hash(drbg, drbg->C, &seedlist); 687 if (ret) 688 return ret; 689 drbg_kcapi_hmacsetkey(drbg, drbg->C); 690 691 /* 10.1.2.2 step 2 and 5 -- HMAC for V */ 692 ret = drbg_kcapi_hash(drbg, drbg->V, &vdatalist); 693 if (ret) 694 return ret; 695 696 /* 10.1.2.2 step 3 */ 697 if (!seed) 698 return ret; 699 } 700 701 return 0; 702 } 703 704 /* generate function of HMAC DRBG as defined in 10.1.2.5 */ 705 static int drbg_hmac_generate(struct drbg_state *drbg, 706 unsigned char *buf, 707 unsigned int buflen, 708 struct list_head *addtl) 709 { 710 int len = 0; 711 int ret = 0; 712 struct drbg_string data; 713 LIST_HEAD(datalist); 714 715 /* 10.1.2.5 step 2 */ 716 if (addtl && !list_empty(addtl)) { 717 ret = drbg_hmac_update(drbg, addtl, 1); 718 if (ret) 719 return ret; 720 } 721 722 drbg_string_fill(&data, drbg->V, drbg_statelen(drbg)); 723 list_add_tail(&data.list, &datalist); 724 while (len < buflen) { 725 unsigned int outlen = 0; 726 /* 10.1.2.5 step 4.1 */ 727 ret = drbg_kcapi_hash(drbg, drbg->V, &datalist); 728 if (ret) 729 return ret; 730 outlen = (drbg_blocklen(drbg) < (buflen - len)) ? 731 drbg_blocklen(drbg) : (buflen - len); 732 733 /* 10.1.2.5 step 4.2 */ 734 memcpy(buf + len, drbg->V, outlen); 735 len += outlen; 736 } 737 738 /* 10.1.2.5 step 6 */ 739 if (addtl && !list_empty(addtl)) 740 ret = drbg_hmac_update(drbg, addtl, 1); 741 else 742 ret = drbg_hmac_update(drbg, NULL, 1); 743 if (ret) 744 return ret; 745 746 return len; 747 } 748 749 static const struct drbg_state_ops drbg_hmac_ops = { 750 .update = drbg_hmac_update, 751 .generate = drbg_hmac_generate, 752 .crypto_init = drbg_init_hash_kernel, 753 .crypto_fini = drbg_fini_hash_kernel, 754 }; 755 #endif /* CONFIG_CRYPTO_DRBG_HMAC */ 756 757 /****************************************************************** 758 * Hash DRBG callback functions 759 ******************************************************************/ 760 761 #ifdef CONFIG_CRYPTO_DRBG_HASH 762 #define CRYPTO_DRBG_HASH_STRING "HASH " 763 MODULE_ALIAS_CRYPTO("drbg_pr_sha512"); 764 MODULE_ALIAS_CRYPTO("drbg_nopr_sha512"); 765 MODULE_ALIAS_CRYPTO("drbg_pr_sha384"); 766 MODULE_ALIAS_CRYPTO("drbg_nopr_sha384"); 767 MODULE_ALIAS_CRYPTO("drbg_pr_sha256"); 768 MODULE_ALIAS_CRYPTO("drbg_nopr_sha256"); 769 MODULE_ALIAS_CRYPTO("drbg_pr_sha1"); 770 MODULE_ALIAS_CRYPTO("drbg_nopr_sha1"); 771 772 /* 773 * Increment buffer 774 * 775 * @dst buffer to increment 776 * @add value to add 777 */ 778 static inline void drbg_add_buf(unsigned char *dst, size_t dstlen, 779 const unsigned char *add, size_t addlen) 780 { 781 /* implied: dstlen > addlen */ 782 unsigned char *dstptr; 783 const unsigned char *addptr; 784 unsigned int remainder = 0; 785 size_t len = addlen; 786 787 dstptr = dst + (dstlen-1); 788 addptr = add + (addlen-1); 789 while (len) { 790 remainder += *dstptr + *addptr; 791 *dstptr = remainder & 0xff; 792 remainder >>= 8; 793 len--; dstptr--; addptr--; 794 } 795 len = dstlen - addlen; 796 while (len && remainder > 0) { 797 remainder = *dstptr + 1; 798 *dstptr = remainder & 0xff; 799 remainder >>= 8; 800 len--; dstptr--; 801 } 802 } 803 804 /* 805 * scratchpad usage: as drbg_hash_update and drbg_hash_df are used 806 * interlinked, the scratchpad is used as follows: 807 * drbg_hash_update 808 * start: drbg->scratchpad 809 * length: drbg_statelen(drbg) 810 * drbg_hash_df: 811 * start: drbg->scratchpad + drbg_statelen(drbg) 812 * length: drbg_blocklen(drbg) 813 * 814 * drbg_hash_process_addtl uses the scratchpad, but fully completes 815 * before either of the functions mentioned before are invoked. Therefore, 816 * drbg_hash_process_addtl does not need to be specifically considered. 817 */ 818 819 /* Derivation Function for Hash DRBG as defined in 10.4.1 */ 820 static int drbg_hash_df(struct drbg_state *drbg, 821 unsigned char *outval, size_t outlen, 822 struct list_head *entropylist) 823 { 824 int ret = 0; 825 size_t len = 0; 826 unsigned char input[5]; 827 unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg); 828 struct drbg_string data; 829 830 /* 10.4.1 step 3 */ 831 input[0] = 1; 832 drbg_cpu_to_be32((outlen * 8), &input[1]); 833 834 /* 10.4.1 step 4.1 -- concatenation of data for input into hash */ 835 drbg_string_fill(&data, input, 5); 836 list_add(&data.list, entropylist); 837 838 /* 10.4.1 step 4 */ 839 while (len < outlen) { 840 short blocklen = 0; 841 /* 10.4.1 step 4.1 */ 842 ret = drbg_kcapi_hash(drbg, tmp, entropylist); 843 if (ret) 844 goto out; 845 /* 10.4.1 step 4.2 */ 846 input[0]++; 847 blocklen = (drbg_blocklen(drbg) < (outlen - len)) ? 848 drbg_blocklen(drbg) : (outlen - len); 849 memcpy(outval + len, tmp, blocklen); 850 len += blocklen; 851 } 852 853 out: 854 memset(tmp, 0, drbg_blocklen(drbg)); 855 return ret; 856 } 857 858 /* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */ 859 static int drbg_hash_update(struct drbg_state *drbg, struct list_head *seed, 860 int reseed) 861 { 862 int ret = 0; 863 struct drbg_string data1, data2; 864 LIST_HEAD(datalist); 865 LIST_HEAD(datalist2); 866 unsigned char *V = drbg->scratchpad; 867 unsigned char prefix = DRBG_PREFIX1; 868 869 if (!seed) 870 return -EINVAL; 871 872 if (reseed) { 873 /* 10.1.1.3 step 1 */ 874 memcpy(V, drbg->V, drbg_statelen(drbg)); 875 drbg_string_fill(&data1, &prefix, 1); 876 list_add_tail(&data1.list, &datalist); 877 drbg_string_fill(&data2, V, drbg_statelen(drbg)); 878 list_add_tail(&data2.list, &datalist); 879 } 880 list_splice_tail(seed, &datalist); 881 882 /* 10.1.1.2 / 10.1.1.3 step 2 and 3 */ 883 ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &datalist); 884 if (ret) 885 goto out; 886 887 /* 10.1.1.2 / 10.1.1.3 step 4 */ 888 prefix = DRBG_PREFIX0; 889 drbg_string_fill(&data1, &prefix, 1); 890 list_add_tail(&data1.list, &datalist2); 891 drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg)); 892 list_add_tail(&data2.list, &datalist2); 893 /* 10.1.1.2 / 10.1.1.3 step 4 */ 894 ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2); 895 896 out: 897 memset(drbg->scratchpad, 0, drbg_statelen(drbg)); 898 return ret; 899 } 900 901 /* processing of additional information string for Hash DRBG */ 902 static int drbg_hash_process_addtl(struct drbg_state *drbg, 903 struct list_head *addtl) 904 { 905 int ret = 0; 906 struct drbg_string data1, data2; 907 LIST_HEAD(datalist); 908 unsigned char prefix = DRBG_PREFIX2; 909 910 /* 10.1.1.4 step 2 */ 911 if (!addtl || list_empty(addtl)) 912 return 0; 913 914 /* 10.1.1.4 step 2a */ 915 drbg_string_fill(&data1, &prefix, 1); 916 drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg)); 917 list_add_tail(&data1.list, &datalist); 918 list_add_tail(&data2.list, &datalist); 919 list_splice_tail(addtl, &datalist); 920 ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist); 921 if (ret) 922 goto out; 923 924 /* 10.1.1.4 step 2b */ 925 drbg_add_buf(drbg->V, drbg_statelen(drbg), 926 drbg->scratchpad, drbg_blocklen(drbg)); 927 928 out: 929 memset(drbg->scratchpad, 0, drbg_blocklen(drbg)); 930 return ret; 931 } 932 933 /* Hashgen defined in 10.1.1.4 */ 934 static int drbg_hash_hashgen(struct drbg_state *drbg, 935 unsigned char *buf, 936 unsigned int buflen) 937 { 938 int len = 0; 939 int ret = 0; 940 unsigned char *src = drbg->scratchpad; 941 unsigned char *dst = drbg->scratchpad + drbg_statelen(drbg); 942 struct drbg_string data; 943 LIST_HEAD(datalist); 944 945 /* 10.1.1.4 step hashgen 2 */ 946 memcpy(src, drbg->V, drbg_statelen(drbg)); 947 948 drbg_string_fill(&data, src, drbg_statelen(drbg)); 949 list_add_tail(&data.list, &datalist); 950 while (len < buflen) { 951 unsigned int outlen = 0; 952 /* 10.1.1.4 step hashgen 4.1 */ 953 ret = drbg_kcapi_hash(drbg, dst, &datalist); 954 if (ret) { 955 len = ret; 956 goto out; 957 } 958 outlen = (drbg_blocklen(drbg) < (buflen - len)) ? 959 drbg_blocklen(drbg) : (buflen - len); 960 /* 10.1.1.4 step hashgen 4.2 */ 961 memcpy(buf + len, dst, outlen); 962 len += outlen; 963 /* 10.1.1.4 hashgen step 4.3 */ 964 if (len < buflen) 965 crypto_inc(src, drbg_statelen(drbg)); 966 } 967 968 out: 969 memset(drbg->scratchpad, 0, 970 (drbg_statelen(drbg) + drbg_blocklen(drbg))); 971 return len; 972 } 973 974 /* generate function for Hash DRBG as defined in 10.1.1.4 */ 975 static int drbg_hash_generate(struct drbg_state *drbg, 976 unsigned char *buf, unsigned int buflen, 977 struct list_head *addtl) 978 { 979 int len = 0; 980 int ret = 0; 981 union { 982 unsigned char req[8]; 983 __be64 req_int; 984 } u; 985 unsigned char prefix = DRBG_PREFIX3; 986 struct drbg_string data1, data2; 987 LIST_HEAD(datalist); 988 989 /* 10.1.1.4 step 2 */ 990 ret = drbg_hash_process_addtl(drbg, addtl); 991 if (ret) 992 return ret; 993 /* 10.1.1.4 step 3 */ 994 len = drbg_hash_hashgen(drbg, buf, buflen); 995 996 /* this is the value H as documented in 10.1.1.4 */ 997 /* 10.1.1.4 step 4 */ 998 drbg_string_fill(&data1, &prefix, 1); 999 list_add_tail(&data1.list, &datalist); 1000 drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg)); 1001 list_add_tail(&data2.list, &datalist); 1002 ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist); 1003 if (ret) { 1004 len = ret; 1005 goto out; 1006 } 1007 1008 /* 10.1.1.4 step 5 */ 1009 drbg_add_buf(drbg->V, drbg_statelen(drbg), 1010 drbg->scratchpad, drbg_blocklen(drbg)); 1011 drbg_add_buf(drbg->V, drbg_statelen(drbg), 1012 drbg->C, drbg_statelen(drbg)); 1013 u.req_int = cpu_to_be64(drbg->reseed_ctr); 1014 drbg_add_buf(drbg->V, drbg_statelen(drbg), u.req, 8); 1015 1016 out: 1017 memset(drbg->scratchpad, 0, drbg_blocklen(drbg)); 1018 return len; 1019 } 1020 1021 /* 1022 * scratchpad usage: as update and generate are used isolated, both 1023 * can use the scratchpad 1024 */ 1025 static const struct drbg_state_ops drbg_hash_ops = { 1026 .update = drbg_hash_update, 1027 .generate = drbg_hash_generate, 1028 .crypto_init = drbg_init_hash_kernel, 1029 .crypto_fini = drbg_fini_hash_kernel, 1030 }; 1031 #endif /* CONFIG_CRYPTO_DRBG_HASH */ 1032 1033 /****************************************************************** 1034 * Functions common for DRBG implementations 1035 ******************************************************************/ 1036 1037 static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed, 1038 int reseed) 1039 { 1040 int ret = drbg->d_ops->update(drbg, seed, reseed); 1041 1042 if (ret) 1043 return ret; 1044 1045 drbg->seeded = true; 1046 /* 10.1.1.2 / 10.1.1.3 step 5 */ 1047 drbg->reseed_ctr = 1; 1048 1049 return ret; 1050 } 1051 1052 static inline int drbg_get_random_bytes(struct drbg_state *drbg, 1053 unsigned char *entropy, 1054 unsigned int entropylen) 1055 { 1056 int ret; 1057 1058 do { 1059 get_random_bytes(entropy, entropylen); 1060 ret = drbg_fips_continuous_test(drbg, entropy); 1061 if (ret && ret != -EAGAIN) 1062 return ret; 1063 } while (ret); 1064 1065 return 0; 1066 } 1067 1068 static void drbg_async_seed(struct work_struct *work) 1069 { 1070 struct drbg_string data; 1071 LIST_HEAD(seedlist); 1072 struct drbg_state *drbg = container_of(work, struct drbg_state, 1073 seed_work); 1074 unsigned int entropylen = drbg_sec_strength(drbg->core->flags); 1075 unsigned char entropy[32]; 1076 int ret; 1077 1078 BUG_ON(!entropylen); 1079 BUG_ON(entropylen > sizeof(entropy)); 1080 1081 drbg_string_fill(&data, entropy, entropylen); 1082 list_add_tail(&data.list, &seedlist); 1083 1084 mutex_lock(&drbg->drbg_mutex); 1085 1086 ret = drbg_get_random_bytes(drbg, entropy, entropylen); 1087 if (ret) 1088 goto unlock; 1089 1090 /* If nonblocking pool is initialized, deactivate Jitter RNG */ 1091 crypto_free_rng(drbg->jent); 1092 drbg->jent = NULL; 1093 1094 /* Set seeded to false so that if __drbg_seed fails the 1095 * next generate call will trigger a reseed. 1096 */ 1097 drbg->seeded = false; 1098 1099 __drbg_seed(drbg, &seedlist, true); 1100 1101 if (drbg->seeded) 1102 drbg->reseed_threshold = drbg_max_requests(drbg); 1103 1104 unlock: 1105 mutex_unlock(&drbg->drbg_mutex); 1106 1107 memzero_explicit(entropy, entropylen); 1108 } 1109 1110 /* 1111 * Seeding or reseeding of the DRBG 1112 * 1113 * @drbg: DRBG state struct 1114 * @pers: personalization / additional information buffer 1115 * @reseed: 0 for initial seed process, 1 for reseeding 1116 * 1117 * return: 1118 * 0 on success 1119 * error value otherwise 1120 */ 1121 static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers, 1122 bool reseed) 1123 { 1124 int ret; 1125 unsigned char entropy[((32 + 16) * 2)]; 1126 unsigned int entropylen = drbg_sec_strength(drbg->core->flags); 1127 struct drbg_string data1; 1128 LIST_HEAD(seedlist); 1129 1130 /* 9.1 / 9.2 / 9.3.1 step 3 */ 1131 if (pers && pers->len > (drbg_max_addtl(drbg))) { 1132 pr_devel("DRBG: personalization string too long %zu\n", 1133 pers->len); 1134 return -EINVAL; 1135 } 1136 1137 if (list_empty(&drbg->test_data.list)) { 1138 drbg_string_fill(&data1, drbg->test_data.buf, 1139 drbg->test_data.len); 1140 pr_devel("DRBG: using test entropy\n"); 1141 } else { 1142 /* 1143 * Gather entropy equal to the security strength of the DRBG. 1144 * With a derivation function, a nonce is required in addition 1145 * to the entropy. A nonce must be at least 1/2 of the security 1146 * strength of the DRBG in size. Thus, entropy + nonce is 3/2 1147 * of the strength. The consideration of a nonce is only 1148 * applicable during initial seeding. 1149 */ 1150 BUG_ON(!entropylen); 1151 if (!reseed) 1152 entropylen = ((entropylen + 1) / 2) * 3; 1153 BUG_ON((entropylen * 2) > sizeof(entropy)); 1154 1155 /* Get seed from in-kernel /dev/urandom */ 1156 ret = drbg_get_random_bytes(drbg, entropy, entropylen); 1157 if (ret) 1158 goto out; 1159 1160 if (!drbg->jent) { 1161 drbg_string_fill(&data1, entropy, entropylen); 1162 pr_devel("DRBG: (re)seeding with %u bytes of entropy\n", 1163 entropylen); 1164 } else { 1165 /* Get seed from Jitter RNG */ 1166 ret = crypto_rng_get_bytes(drbg->jent, 1167 entropy + entropylen, 1168 entropylen); 1169 if (ret) { 1170 pr_devel("DRBG: jent failed with %d\n", ret); 1171 goto out; 1172 } 1173 1174 drbg_string_fill(&data1, entropy, entropylen * 2); 1175 pr_devel("DRBG: (re)seeding with %u bytes of entropy\n", 1176 entropylen * 2); 1177 } 1178 } 1179 list_add_tail(&data1.list, &seedlist); 1180 1181 /* 1182 * concatenation of entropy with personalization str / addtl input) 1183 * the variable pers is directly handed in by the caller, so check its 1184 * contents whether it is appropriate 1185 */ 1186 if (pers && pers->buf && 0 < pers->len) { 1187 list_add_tail(&pers->list, &seedlist); 1188 pr_devel("DRBG: using personalization string\n"); 1189 } 1190 1191 if (!reseed) { 1192 memset(drbg->V, 0, drbg_statelen(drbg)); 1193 memset(drbg->C, 0, drbg_statelen(drbg)); 1194 } 1195 1196 ret = __drbg_seed(drbg, &seedlist, reseed); 1197 1198 out: 1199 memzero_explicit(entropy, entropylen * 2); 1200 1201 return ret; 1202 } 1203 1204 /* Free all substructures in a DRBG state without the DRBG state structure */ 1205 static inline void drbg_dealloc_state(struct drbg_state *drbg) 1206 { 1207 if (!drbg) 1208 return; 1209 kzfree(drbg->Vbuf); 1210 drbg->Vbuf = NULL; 1211 drbg->V = NULL; 1212 kzfree(drbg->Cbuf); 1213 drbg->Cbuf = NULL; 1214 drbg->C = NULL; 1215 kzfree(drbg->scratchpadbuf); 1216 drbg->scratchpadbuf = NULL; 1217 drbg->reseed_ctr = 0; 1218 drbg->d_ops = NULL; 1219 drbg->core = NULL; 1220 if (IS_ENABLED(CONFIG_CRYPTO_FIPS)) { 1221 kzfree(drbg->prev); 1222 drbg->prev = NULL; 1223 drbg->fips_primed = false; 1224 } 1225 } 1226 1227 /* 1228 * Allocate all sub-structures for a DRBG state. 1229 * The DRBG state structure must already be allocated. 1230 */ 1231 static inline int drbg_alloc_state(struct drbg_state *drbg) 1232 { 1233 int ret = -ENOMEM; 1234 unsigned int sb_size = 0; 1235 1236 switch (drbg->core->flags & DRBG_TYPE_MASK) { 1237 #ifdef CONFIG_CRYPTO_DRBG_HMAC 1238 case DRBG_HMAC: 1239 drbg->d_ops = &drbg_hmac_ops; 1240 break; 1241 #endif /* CONFIG_CRYPTO_DRBG_HMAC */ 1242 #ifdef CONFIG_CRYPTO_DRBG_HASH 1243 case DRBG_HASH: 1244 drbg->d_ops = &drbg_hash_ops; 1245 break; 1246 #endif /* CONFIG_CRYPTO_DRBG_HASH */ 1247 #ifdef CONFIG_CRYPTO_DRBG_CTR 1248 case DRBG_CTR: 1249 drbg->d_ops = &drbg_ctr_ops; 1250 break; 1251 #endif /* CONFIG_CRYPTO_DRBG_CTR */ 1252 default: 1253 ret = -EOPNOTSUPP; 1254 goto err; 1255 } 1256 1257 ret = drbg->d_ops->crypto_init(drbg); 1258 if (ret < 0) 1259 goto err; 1260 1261 drbg->Vbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL); 1262 if (!drbg->Vbuf) { 1263 ret = -ENOMEM; 1264 goto fini; 1265 } 1266 drbg->V = PTR_ALIGN(drbg->Vbuf, ret + 1); 1267 drbg->Cbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL); 1268 if (!drbg->Cbuf) { 1269 ret = -ENOMEM; 1270 goto fini; 1271 } 1272 drbg->C = PTR_ALIGN(drbg->Cbuf, ret + 1); 1273 /* scratchpad is only generated for CTR and Hash */ 1274 if (drbg->core->flags & DRBG_HMAC) 1275 sb_size = 0; 1276 else if (drbg->core->flags & DRBG_CTR) 1277 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg) + /* temp */ 1278 drbg_statelen(drbg) + /* df_data */ 1279 drbg_blocklen(drbg) + /* pad */ 1280 drbg_blocklen(drbg) + /* iv */ 1281 drbg_statelen(drbg) + drbg_blocklen(drbg); /* temp */ 1282 else 1283 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg); 1284 1285 if (0 < sb_size) { 1286 drbg->scratchpadbuf = kzalloc(sb_size + ret, GFP_KERNEL); 1287 if (!drbg->scratchpadbuf) { 1288 ret = -ENOMEM; 1289 goto fini; 1290 } 1291 drbg->scratchpad = PTR_ALIGN(drbg->scratchpadbuf, ret + 1); 1292 } 1293 1294 if (IS_ENABLED(CONFIG_CRYPTO_FIPS)) { 1295 drbg->prev = kzalloc(drbg_sec_strength(drbg->core->flags), 1296 GFP_KERNEL); 1297 if (!drbg->prev) 1298 goto fini; 1299 drbg->fips_primed = false; 1300 } 1301 1302 return 0; 1303 1304 fini: 1305 drbg->d_ops->crypto_fini(drbg); 1306 err: 1307 drbg_dealloc_state(drbg); 1308 return ret; 1309 } 1310 1311 /************************************************************************* 1312 * DRBG interface functions 1313 *************************************************************************/ 1314 1315 /* 1316 * DRBG generate function as required by SP800-90A - this function 1317 * generates random numbers 1318 * 1319 * @drbg DRBG state handle 1320 * @buf Buffer where to store the random numbers -- the buffer must already 1321 * be pre-allocated by caller 1322 * @buflen Length of output buffer - this value defines the number of random 1323 * bytes pulled from DRBG 1324 * @addtl Additional input that is mixed into state, may be NULL -- note 1325 * the entropy is pulled by the DRBG internally unconditionally 1326 * as defined in SP800-90A. The additional input is mixed into 1327 * the state in addition to the pulled entropy. 1328 * 1329 * return: 0 when all bytes are generated; < 0 in case of an error 1330 */ 1331 static int drbg_generate(struct drbg_state *drbg, 1332 unsigned char *buf, unsigned int buflen, 1333 struct drbg_string *addtl) 1334 { 1335 int len = 0; 1336 LIST_HEAD(addtllist); 1337 1338 if (!drbg->core) { 1339 pr_devel("DRBG: not yet seeded\n"); 1340 return -EINVAL; 1341 } 1342 if (0 == buflen || !buf) { 1343 pr_devel("DRBG: no output buffer provided\n"); 1344 return -EINVAL; 1345 } 1346 if (addtl && NULL == addtl->buf && 0 < addtl->len) { 1347 pr_devel("DRBG: wrong format of additional information\n"); 1348 return -EINVAL; 1349 } 1350 1351 /* 9.3.1 step 2 */ 1352 len = -EINVAL; 1353 if (buflen > (drbg_max_request_bytes(drbg))) { 1354 pr_devel("DRBG: requested random numbers too large %u\n", 1355 buflen); 1356 goto err; 1357 } 1358 1359 /* 9.3.1 step 3 is implicit with the chosen DRBG */ 1360 1361 /* 9.3.1 step 4 */ 1362 if (addtl && addtl->len > (drbg_max_addtl(drbg))) { 1363 pr_devel("DRBG: additional information string too long %zu\n", 1364 addtl->len); 1365 goto err; 1366 } 1367 /* 9.3.1 step 5 is implicit with the chosen DRBG */ 1368 1369 /* 1370 * 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented 1371 * here. The spec is a bit convoluted here, we make it simpler. 1372 */ 1373 if (drbg->reseed_threshold < drbg->reseed_ctr) 1374 drbg->seeded = false; 1375 1376 if (drbg->pr || !drbg->seeded) { 1377 pr_devel("DRBG: reseeding before generation (prediction " 1378 "resistance: %s, state %s)\n", 1379 drbg->pr ? "true" : "false", 1380 drbg->seeded ? "seeded" : "unseeded"); 1381 /* 9.3.1 steps 7.1 through 7.3 */ 1382 len = drbg_seed(drbg, addtl, true); 1383 if (len) 1384 goto err; 1385 /* 9.3.1 step 7.4 */ 1386 addtl = NULL; 1387 } 1388 1389 if (addtl && 0 < addtl->len) 1390 list_add_tail(&addtl->list, &addtllist); 1391 /* 9.3.1 step 8 and 10 */ 1392 len = drbg->d_ops->generate(drbg, buf, buflen, &addtllist); 1393 1394 /* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */ 1395 drbg->reseed_ctr++; 1396 if (0 >= len) 1397 goto err; 1398 1399 /* 1400 * Section 11.3.3 requires to re-perform self tests after some 1401 * generated random numbers. The chosen value after which self 1402 * test is performed is arbitrary, but it should be reasonable. 1403 * However, we do not perform the self tests because of the following 1404 * reasons: it is mathematically impossible that the initial self tests 1405 * were successfully and the following are not. If the initial would 1406 * pass and the following would not, the kernel integrity is violated. 1407 * In this case, the entire kernel operation is questionable and it 1408 * is unlikely that the integrity violation only affects the 1409 * correct operation of the DRBG. 1410 * 1411 * Albeit the following code is commented out, it is provided in 1412 * case somebody has a need to implement the test of 11.3.3. 1413 */ 1414 #if 0 1415 if (drbg->reseed_ctr && !(drbg->reseed_ctr % 4096)) { 1416 int err = 0; 1417 pr_devel("DRBG: start to perform self test\n"); 1418 if (drbg->core->flags & DRBG_HMAC) 1419 err = alg_test("drbg_pr_hmac_sha256", 1420 "drbg_pr_hmac_sha256", 0, 0); 1421 else if (drbg->core->flags & DRBG_CTR) 1422 err = alg_test("drbg_pr_ctr_aes128", 1423 "drbg_pr_ctr_aes128", 0, 0); 1424 else 1425 err = alg_test("drbg_pr_sha256", 1426 "drbg_pr_sha256", 0, 0); 1427 if (err) { 1428 pr_err("DRBG: periodical self test failed\n"); 1429 /* 1430 * uninstantiate implies that from now on, only errors 1431 * are returned when reusing this DRBG cipher handle 1432 */ 1433 drbg_uninstantiate(drbg); 1434 return 0; 1435 } else { 1436 pr_devel("DRBG: self test successful\n"); 1437 } 1438 } 1439 #endif 1440 1441 /* 1442 * All operations were successful, return 0 as mandated by 1443 * the kernel crypto API interface. 1444 */ 1445 len = 0; 1446 err: 1447 return len; 1448 } 1449 1450 /* 1451 * Wrapper around drbg_generate which can pull arbitrary long strings 1452 * from the DRBG without hitting the maximum request limitation. 1453 * 1454 * Parameters: see drbg_generate 1455 * Return codes: see drbg_generate -- if one drbg_generate request fails, 1456 * the entire drbg_generate_long request fails 1457 */ 1458 static int drbg_generate_long(struct drbg_state *drbg, 1459 unsigned char *buf, unsigned int buflen, 1460 struct drbg_string *addtl) 1461 { 1462 unsigned int len = 0; 1463 unsigned int slice = 0; 1464 do { 1465 int err = 0; 1466 unsigned int chunk = 0; 1467 slice = ((buflen - len) / drbg_max_request_bytes(drbg)); 1468 chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len); 1469 mutex_lock(&drbg->drbg_mutex); 1470 err = drbg_generate(drbg, buf + len, chunk, addtl); 1471 mutex_unlock(&drbg->drbg_mutex); 1472 if (0 > err) 1473 return err; 1474 len += chunk; 1475 } while (slice > 0 && (len < buflen)); 1476 return 0; 1477 } 1478 1479 static void drbg_schedule_async_seed(struct random_ready_callback *rdy) 1480 { 1481 struct drbg_state *drbg = container_of(rdy, struct drbg_state, 1482 random_ready); 1483 1484 schedule_work(&drbg->seed_work); 1485 } 1486 1487 static int drbg_prepare_hrng(struct drbg_state *drbg) 1488 { 1489 int err; 1490 1491 /* We do not need an HRNG in test mode. */ 1492 if (list_empty(&drbg->test_data.list)) 1493 return 0; 1494 1495 INIT_WORK(&drbg->seed_work, drbg_async_seed); 1496 1497 drbg->random_ready.owner = THIS_MODULE; 1498 drbg->random_ready.func = drbg_schedule_async_seed; 1499 1500 err = add_random_ready_callback(&drbg->random_ready); 1501 1502 switch (err) { 1503 case 0: 1504 break; 1505 1506 case -EALREADY: 1507 err = 0; 1508 /* fall through */ 1509 1510 default: 1511 drbg->random_ready.func = NULL; 1512 return err; 1513 } 1514 1515 drbg->jent = crypto_alloc_rng("jitterentropy_rng", 0, 0); 1516 1517 /* 1518 * Require frequent reseeds until the seed source is fully 1519 * initialized. 1520 */ 1521 drbg->reseed_threshold = 50; 1522 1523 return err; 1524 } 1525 1526 /* 1527 * DRBG instantiation function as required by SP800-90A - this function 1528 * sets up the DRBG handle, performs the initial seeding and all sanity 1529 * checks required by SP800-90A 1530 * 1531 * @drbg memory of state -- if NULL, new memory is allocated 1532 * @pers Personalization string that is mixed into state, may be NULL -- note 1533 * the entropy is pulled by the DRBG internally unconditionally 1534 * as defined in SP800-90A. The additional input is mixed into 1535 * the state in addition to the pulled entropy. 1536 * @coreref reference to core 1537 * @pr prediction resistance enabled 1538 * 1539 * return 1540 * 0 on success 1541 * error value otherwise 1542 */ 1543 static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers, 1544 int coreref, bool pr) 1545 { 1546 int ret; 1547 bool reseed = true; 1548 1549 pr_devel("DRBG: Initializing DRBG core %d with prediction resistance " 1550 "%s\n", coreref, pr ? "enabled" : "disabled"); 1551 mutex_lock(&drbg->drbg_mutex); 1552 1553 /* 9.1 step 1 is implicit with the selected DRBG type */ 1554 1555 /* 1556 * 9.1 step 2 is implicit as caller can select prediction resistance 1557 * and the flag is copied into drbg->flags -- 1558 * all DRBG types support prediction resistance 1559 */ 1560 1561 /* 9.1 step 4 is implicit in drbg_sec_strength */ 1562 1563 if (!drbg->core) { 1564 drbg->core = &drbg_cores[coreref]; 1565 drbg->pr = pr; 1566 drbg->seeded = false; 1567 drbg->reseed_threshold = drbg_max_requests(drbg); 1568 1569 ret = drbg_alloc_state(drbg); 1570 if (ret) 1571 goto unlock; 1572 1573 ret = drbg_prepare_hrng(drbg); 1574 if (ret) 1575 goto free_everything; 1576 1577 if (IS_ERR(drbg->jent)) { 1578 ret = PTR_ERR(drbg->jent); 1579 drbg->jent = NULL; 1580 if (fips_enabled || ret != -ENOENT) 1581 goto free_everything; 1582 pr_info("DRBG: Continuing without Jitter RNG\n"); 1583 } 1584 1585 reseed = false; 1586 } 1587 1588 ret = drbg_seed(drbg, pers, reseed); 1589 1590 if (ret && !reseed) 1591 goto free_everything; 1592 1593 mutex_unlock(&drbg->drbg_mutex); 1594 return ret; 1595 1596 unlock: 1597 mutex_unlock(&drbg->drbg_mutex); 1598 return ret; 1599 1600 free_everything: 1601 mutex_unlock(&drbg->drbg_mutex); 1602 drbg_uninstantiate(drbg); 1603 return ret; 1604 } 1605 1606 /* 1607 * DRBG uninstantiate function as required by SP800-90A - this function 1608 * frees all buffers and the DRBG handle 1609 * 1610 * @drbg DRBG state handle 1611 * 1612 * return 1613 * 0 on success 1614 */ 1615 static int drbg_uninstantiate(struct drbg_state *drbg) 1616 { 1617 if (drbg->random_ready.func) { 1618 del_random_ready_callback(&drbg->random_ready); 1619 cancel_work_sync(&drbg->seed_work); 1620 crypto_free_rng(drbg->jent); 1621 drbg->jent = NULL; 1622 } 1623 1624 if (drbg->d_ops) 1625 drbg->d_ops->crypto_fini(drbg); 1626 drbg_dealloc_state(drbg); 1627 /* no scrubbing of test_data -- this shall survive an uninstantiate */ 1628 return 0; 1629 } 1630 1631 /* 1632 * Helper function for setting the test data in the DRBG 1633 * 1634 * @drbg DRBG state handle 1635 * @data test data 1636 * @len test data length 1637 */ 1638 static void drbg_kcapi_set_entropy(struct crypto_rng *tfm, 1639 const u8 *data, unsigned int len) 1640 { 1641 struct drbg_state *drbg = crypto_rng_ctx(tfm); 1642 1643 mutex_lock(&drbg->drbg_mutex); 1644 drbg_string_fill(&drbg->test_data, data, len); 1645 mutex_unlock(&drbg->drbg_mutex); 1646 } 1647 1648 /*************************************************************** 1649 * Kernel crypto API cipher invocations requested by DRBG 1650 ***************************************************************/ 1651 1652 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC) 1653 struct sdesc { 1654 struct shash_desc shash; 1655 char ctx[]; 1656 }; 1657 1658 static int drbg_init_hash_kernel(struct drbg_state *drbg) 1659 { 1660 struct sdesc *sdesc; 1661 struct crypto_shash *tfm; 1662 1663 tfm = crypto_alloc_shash(drbg->core->backend_cra_name, 0, 0); 1664 if (IS_ERR(tfm)) { 1665 pr_info("DRBG: could not allocate digest TFM handle: %s\n", 1666 drbg->core->backend_cra_name); 1667 return PTR_ERR(tfm); 1668 } 1669 BUG_ON(drbg_blocklen(drbg) != crypto_shash_digestsize(tfm)); 1670 sdesc = kzalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm), 1671 GFP_KERNEL); 1672 if (!sdesc) { 1673 crypto_free_shash(tfm); 1674 return -ENOMEM; 1675 } 1676 1677 sdesc->shash.tfm = tfm; 1678 drbg->priv_data = sdesc; 1679 1680 return crypto_shash_alignmask(tfm); 1681 } 1682 1683 static int drbg_fini_hash_kernel(struct drbg_state *drbg) 1684 { 1685 struct sdesc *sdesc = (struct sdesc *)drbg->priv_data; 1686 if (sdesc) { 1687 crypto_free_shash(sdesc->shash.tfm); 1688 kzfree(sdesc); 1689 } 1690 drbg->priv_data = NULL; 1691 return 0; 1692 } 1693 1694 static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg, 1695 const unsigned char *key) 1696 { 1697 struct sdesc *sdesc = (struct sdesc *)drbg->priv_data; 1698 1699 crypto_shash_setkey(sdesc->shash.tfm, key, drbg_statelen(drbg)); 1700 } 1701 1702 static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval, 1703 const struct list_head *in) 1704 { 1705 struct sdesc *sdesc = (struct sdesc *)drbg->priv_data; 1706 struct drbg_string *input = NULL; 1707 1708 crypto_shash_init(&sdesc->shash); 1709 list_for_each_entry(input, in, list) 1710 crypto_shash_update(&sdesc->shash, input->buf, input->len); 1711 return crypto_shash_final(&sdesc->shash, outval); 1712 } 1713 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */ 1714 1715 #ifdef CONFIG_CRYPTO_DRBG_CTR 1716 static int drbg_fini_sym_kernel(struct drbg_state *drbg) 1717 { 1718 struct crypto_cipher *tfm = 1719 (struct crypto_cipher *)drbg->priv_data; 1720 if (tfm) 1721 crypto_free_cipher(tfm); 1722 drbg->priv_data = NULL; 1723 1724 if (drbg->ctr_handle) 1725 crypto_free_skcipher(drbg->ctr_handle); 1726 drbg->ctr_handle = NULL; 1727 1728 if (drbg->ctr_req) 1729 skcipher_request_free(drbg->ctr_req); 1730 drbg->ctr_req = NULL; 1731 1732 kfree(drbg->outscratchpadbuf); 1733 drbg->outscratchpadbuf = NULL; 1734 1735 return 0; 1736 } 1737 1738 static int drbg_init_sym_kernel(struct drbg_state *drbg) 1739 { 1740 struct crypto_cipher *tfm; 1741 struct crypto_skcipher *sk_tfm; 1742 struct skcipher_request *req; 1743 unsigned int alignmask; 1744 char ctr_name[CRYPTO_MAX_ALG_NAME]; 1745 1746 tfm = crypto_alloc_cipher(drbg->core->backend_cra_name, 0, 0); 1747 if (IS_ERR(tfm)) { 1748 pr_info("DRBG: could not allocate cipher TFM handle: %s\n", 1749 drbg->core->backend_cra_name); 1750 return PTR_ERR(tfm); 1751 } 1752 BUG_ON(drbg_blocklen(drbg) != crypto_cipher_blocksize(tfm)); 1753 drbg->priv_data = tfm; 1754 1755 if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)", 1756 drbg->core->backend_cra_name) >= CRYPTO_MAX_ALG_NAME) { 1757 drbg_fini_sym_kernel(drbg); 1758 return -EINVAL; 1759 } 1760 sk_tfm = crypto_alloc_skcipher(ctr_name, 0, 0); 1761 if (IS_ERR(sk_tfm)) { 1762 pr_info("DRBG: could not allocate CTR cipher TFM handle: %s\n", 1763 ctr_name); 1764 drbg_fini_sym_kernel(drbg); 1765 return PTR_ERR(sk_tfm); 1766 } 1767 drbg->ctr_handle = sk_tfm; 1768 crypto_init_wait(&drbg->ctr_wait); 1769 1770 req = skcipher_request_alloc(sk_tfm, GFP_KERNEL); 1771 if (!req) { 1772 pr_info("DRBG: could not allocate request queue\n"); 1773 drbg_fini_sym_kernel(drbg); 1774 return -ENOMEM; 1775 } 1776 drbg->ctr_req = req; 1777 skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG | 1778 CRYPTO_TFM_REQ_MAY_SLEEP, 1779 crypto_req_done, &drbg->ctr_wait); 1780 1781 alignmask = crypto_skcipher_alignmask(sk_tfm); 1782 drbg->outscratchpadbuf = kmalloc(DRBG_OUTSCRATCHLEN + alignmask, 1783 GFP_KERNEL); 1784 if (!drbg->outscratchpadbuf) { 1785 drbg_fini_sym_kernel(drbg); 1786 return -ENOMEM; 1787 } 1788 drbg->outscratchpad = (u8 *)PTR_ALIGN(drbg->outscratchpadbuf, 1789 alignmask + 1); 1790 1791 sg_init_table(&drbg->sg_in, 1); 1792 sg_init_one(&drbg->sg_out, drbg->outscratchpad, DRBG_OUTSCRATCHLEN); 1793 1794 return alignmask; 1795 } 1796 1797 static void drbg_kcapi_symsetkey(struct drbg_state *drbg, 1798 const unsigned char *key) 1799 { 1800 struct crypto_cipher *tfm = 1801 (struct crypto_cipher *)drbg->priv_data; 1802 1803 crypto_cipher_setkey(tfm, key, (drbg_keylen(drbg))); 1804 } 1805 1806 static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval, 1807 const struct drbg_string *in) 1808 { 1809 struct crypto_cipher *tfm = 1810 (struct crypto_cipher *)drbg->priv_data; 1811 1812 /* there is only component in *in */ 1813 BUG_ON(in->len < drbg_blocklen(drbg)); 1814 crypto_cipher_encrypt_one(tfm, outval, in->buf); 1815 return 0; 1816 } 1817 1818 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg, 1819 u8 *inbuf, u32 inlen, 1820 u8 *outbuf, u32 outlen) 1821 { 1822 struct scatterlist *sg_in = &drbg->sg_in, *sg_out = &drbg->sg_out; 1823 u32 scratchpad_use = min_t(u32, outlen, DRBG_OUTSCRATCHLEN); 1824 int ret; 1825 1826 if (inbuf) { 1827 /* Use caller-provided input buffer */ 1828 sg_set_buf(sg_in, inbuf, inlen); 1829 } else { 1830 /* Use scratchpad for in-place operation */ 1831 inlen = scratchpad_use; 1832 memset(drbg->outscratchpad, 0, scratchpad_use); 1833 sg_set_buf(sg_in, drbg->outscratchpad, scratchpad_use); 1834 } 1835 1836 while (outlen) { 1837 u32 cryptlen = min3(inlen, outlen, (u32)DRBG_OUTSCRATCHLEN); 1838 1839 /* Output buffer may not be valid for SGL, use scratchpad */ 1840 skcipher_request_set_crypt(drbg->ctr_req, sg_in, sg_out, 1841 cryptlen, drbg->V); 1842 ret = crypto_wait_req(crypto_skcipher_encrypt(drbg->ctr_req), 1843 &drbg->ctr_wait); 1844 if (ret) 1845 goto out; 1846 1847 crypto_init_wait(&drbg->ctr_wait); 1848 1849 memcpy(outbuf, drbg->outscratchpad, cryptlen); 1850 memzero_explicit(drbg->outscratchpad, cryptlen); 1851 1852 outlen -= cryptlen; 1853 outbuf += cryptlen; 1854 } 1855 ret = 0; 1856 1857 out: 1858 return ret; 1859 } 1860 #endif /* CONFIG_CRYPTO_DRBG_CTR */ 1861 1862 /*************************************************************** 1863 * Kernel crypto API interface to register DRBG 1864 ***************************************************************/ 1865 1866 /* 1867 * Look up the DRBG flags by given kernel crypto API cra_name 1868 * The code uses the drbg_cores definition to do this 1869 * 1870 * @cra_name kernel crypto API cra_name 1871 * @coreref reference to integer which is filled with the pointer to 1872 * the applicable core 1873 * @pr reference for setting prediction resistance 1874 * 1875 * return: flags 1876 */ 1877 static inline void drbg_convert_tfm_core(const char *cra_driver_name, 1878 int *coreref, bool *pr) 1879 { 1880 int i = 0; 1881 size_t start = 0; 1882 int len = 0; 1883 1884 *pr = true; 1885 /* disassemble the names */ 1886 if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) { 1887 start = 10; 1888 *pr = false; 1889 } else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) { 1890 start = 8; 1891 } else { 1892 return; 1893 } 1894 1895 /* remove the first part */ 1896 len = strlen(cra_driver_name) - start; 1897 for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) { 1898 if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name, 1899 len)) { 1900 *coreref = i; 1901 return; 1902 } 1903 } 1904 } 1905 1906 static int drbg_kcapi_init(struct crypto_tfm *tfm) 1907 { 1908 struct drbg_state *drbg = crypto_tfm_ctx(tfm); 1909 1910 mutex_init(&drbg->drbg_mutex); 1911 1912 return 0; 1913 } 1914 1915 static void drbg_kcapi_cleanup(struct crypto_tfm *tfm) 1916 { 1917 drbg_uninstantiate(crypto_tfm_ctx(tfm)); 1918 } 1919 1920 /* 1921 * Generate random numbers invoked by the kernel crypto API: 1922 * The API of the kernel crypto API is extended as follows: 1923 * 1924 * src is additional input supplied to the RNG. 1925 * slen is the length of src. 1926 * dst is the output buffer where random data is to be stored. 1927 * dlen is the length of dst. 1928 */ 1929 static int drbg_kcapi_random(struct crypto_rng *tfm, 1930 const u8 *src, unsigned int slen, 1931 u8 *dst, unsigned int dlen) 1932 { 1933 struct drbg_state *drbg = crypto_rng_ctx(tfm); 1934 struct drbg_string *addtl = NULL; 1935 struct drbg_string string; 1936 1937 if (slen) { 1938 /* linked list variable is now local to allow modification */ 1939 drbg_string_fill(&string, src, slen); 1940 addtl = &string; 1941 } 1942 1943 return drbg_generate_long(drbg, dst, dlen, addtl); 1944 } 1945 1946 /* 1947 * Seed the DRBG invoked by the kernel crypto API 1948 */ 1949 static int drbg_kcapi_seed(struct crypto_rng *tfm, 1950 const u8 *seed, unsigned int slen) 1951 { 1952 struct drbg_state *drbg = crypto_rng_ctx(tfm); 1953 struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm); 1954 bool pr = false; 1955 struct drbg_string string; 1956 struct drbg_string *seed_string = NULL; 1957 int coreref = 0; 1958 1959 drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref, 1960 &pr); 1961 if (0 < slen) { 1962 drbg_string_fill(&string, seed, slen); 1963 seed_string = &string; 1964 } 1965 1966 return drbg_instantiate(drbg, seed_string, coreref, pr); 1967 } 1968 1969 /*************************************************************** 1970 * Kernel module: code to load the module 1971 ***************************************************************/ 1972 1973 /* 1974 * Tests as defined in 11.3.2 in addition to the cipher tests: testing 1975 * of the error handling. 1976 * 1977 * Note: testing of failing seed source as defined in 11.3.2 is not applicable 1978 * as seed source of get_random_bytes does not fail. 1979 * 1980 * Note 2: There is no sensible way of testing the reseed counter 1981 * enforcement, so skip it. 1982 */ 1983 static inline int __init drbg_healthcheck_sanity(void) 1984 { 1985 int len = 0; 1986 #define OUTBUFLEN 16 1987 unsigned char buf[OUTBUFLEN]; 1988 struct drbg_state *drbg = NULL; 1989 int ret = -EFAULT; 1990 int rc = -EFAULT; 1991 bool pr = false; 1992 int coreref = 0; 1993 struct drbg_string addtl; 1994 size_t max_addtllen, max_request_bytes; 1995 1996 /* only perform test in FIPS mode */ 1997 if (!fips_enabled) 1998 return 0; 1999 2000 #ifdef CONFIG_CRYPTO_DRBG_CTR 2001 drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr); 2002 #elif defined CONFIG_CRYPTO_DRBG_HASH 2003 drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr); 2004 #else 2005 drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref, &pr); 2006 #endif 2007 2008 drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL); 2009 if (!drbg) 2010 return -ENOMEM; 2011 2012 mutex_init(&drbg->drbg_mutex); 2013 drbg->core = &drbg_cores[coreref]; 2014 drbg->reseed_threshold = drbg_max_requests(drbg); 2015 2016 /* 2017 * if the following tests fail, it is likely that there is a buffer 2018 * overflow as buf is much smaller than the requested or provided 2019 * string lengths -- in case the error handling does not succeed 2020 * we may get an OOPS. And we want to get an OOPS as this is a 2021 * grave bug. 2022 */ 2023 2024 max_addtllen = drbg_max_addtl(drbg); 2025 max_request_bytes = drbg_max_request_bytes(drbg); 2026 drbg_string_fill(&addtl, buf, max_addtllen + 1); 2027 /* overflow addtllen with additonal info string */ 2028 len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl); 2029 BUG_ON(0 < len); 2030 /* overflow max_bits */ 2031 len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL); 2032 BUG_ON(0 < len); 2033 2034 /* overflow max addtllen with personalization string */ 2035 ret = drbg_seed(drbg, &addtl, false); 2036 BUG_ON(0 == ret); 2037 /* all tests passed */ 2038 rc = 0; 2039 2040 pr_devel("DRBG: Sanity tests for failure code paths successfully " 2041 "completed\n"); 2042 2043 kfree(drbg); 2044 return rc; 2045 } 2046 2047 static struct rng_alg drbg_algs[22]; 2048 2049 /* 2050 * Fill the array drbg_algs used to register the different DRBGs 2051 * with the kernel crypto API. To fill the array, the information 2052 * from drbg_cores[] is used. 2053 */ 2054 static inline void __init drbg_fill_array(struct rng_alg *alg, 2055 const struct drbg_core *core, int pr) 2056 { 2057 int pos = 0; 2058 static int priority = 200; 2059 2060 memcpy(alg->base.cra_name, "stdrng", 6); 2061 if (pr) { 2062 memcpy(alg->base.cra_driver_name, "drbg_pr_", 8); 2063 pos = 8; 2064 } else { 2065 memcpy(alg->base.cra_driver_name, "drbg_nopr_", 10); 2066 pos = 10; 2067 } 2068 memcpy(alg->base.cra_driver_name + pos, core->cra_name, 2069 strlen(core->cra_name)); 2070 2071 alg->base.cra_priority = priority; 2072 priority++; 2073 /* 2074 * If FIPS mode enabled, the selected DRBG shall have the 2075 * highest cra_priority over other stdrng instances to ensure 2076 * it is selected. 2077 */ 2078 if (fips_enabled) 2079 alg->base.cra_priority += 200; 2080 2081 alg->base.cra_ctxsize = sizeof(struct drbg_state); 2082 alg->base.cra_module = THIS_MODULE; 2083 alg->base.cra_init = drbg_kcapi_init; 2084 alg->base.cra_exit = drbg_kcapi_cleanup; 2085 alg->generate = drbg_kcapi_random; 2086 alg->seed = drbg_kcapi_seed; 2087 alg->set_ent = drbg_kcapi_set_entropy; 2088 alg->seedsize = 0; 2089 } 2090 2091 static int __init drbg_init(void) 2092 { 2093 unsigned int i = 0; /* pointer to drbg_algs */ 2094 unsigned int j = 0; /* pointer to drbg_cores */ 2095 int ret; 2096 2097 ret = drbg_healthcheck_sanity(); 2098 if (ret) 2099 return ret; 2100 2101 if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) { 2102 pr_info("DRBG: Cannot register all DRBG types" 2103 "(slots needed: %zu, slots available: %zu)\n", 2104 ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs)); 2105 return -EFAULT; 2106 } 2107 2108 /* 2109 * each DRBG definition can be used with PR and without PR, thus 2110 * we instantiate each DRBG in drbg_cores[] twice. 2111 * 2112 * As the order of placing them into the drbg_algs array matters 2113 * (the later DRBGs receive a higher cra_priority) we register the 2114 * prediction resistance DRBGs first as the should not be too 2115 * interesting. 2116 */ 2117 for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++) 2118 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1); 2119 for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++) 2120 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0); 2121 return crypto_register_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2)); 2122 } 2123 2124 static void __exit drbg_exit(void) 2125 { 2126 crypto_unregister_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2)); 2127 } 2128 2129 subsys_initcall(drbg_init); 2130 module_exit(drbg_exit); 2131 #ifndef CRYPTO_DRBG_HASH_STRING 2132 #define CRYPTO_DRBG_HASH_STRING "" 2133 #endif 2134 #ifndef CRYPTO_DRBG_HMAC_STRING 2135 #define CRYPTO_DRBG_HMAC_STRING "" 2136 #endif 2137 #ifndef CRYPTO_DRBG_CTR_STRING 2138 #define CRYPTO_DRBG_CTR_STRING "" 2139 #endif 2140 MODULE_LICENSE("GPL"); 2141 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>"); 2142 MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) " 2143 "using following cores: " 2144 CRYPTO_DRBG_HASH_STRING 2145 CRYPTO_DRBG_HMAC_STRING 2146 CRYPTO_DRBG_CTR_STRING); 2147 MODULE_ALIAS_CRYPTO("stdrng"); 2148