1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (c) 2020 Hannes Reinecke, SUSE Linux 4 */ 5 6 #include <linux/module.h> 7 #include <linux/crc32.h> 8 #include <linux/base64.h> 9 #include <linux/prandom.h> 10 #include <linux/scatterlist.h> 11 #include <linux/unaligned.h> 12 #include <crypto/hash.h> 13 #include <crypto/dh.h> 14 #include <crypto/hkdf.h> 15 #include <linux/nvme.h> 16 #include <linux/nvme-auth.h> 17 18 #define HKDF_MAX_HASHLEN 64 19 20 static u32 nvme_dhchap_seqnum; 21 static DEFINE_MUTEX(nvme_dhchap_mutex); 22 23 u32 nvme_auth_get_seqnum(void) 24 { 25 u32 seqnum; 26 27 mutex_lock(&nvme_dhchap_mutex); 28 if (!nvme_dhchap_seqnum) 29 nvme_dhchap_seqnum = get_random_u32(); 30 else { 31 nvme_dhchap_seqnum++; 32 if (!nvme_dhchap_seqnum) 33 nvme_dhchap_seqnum++; 34 } 35 seqnum = nvme_dhchap_seqnum; 36 mutex_unlock(&nvme_dhchap_mutex); 37 return seqnum; 38 } 39 EXPORT_SYMBOL_GPL(nvme_auth_get_seqnum); 40 41 static struct nvme_auth_dhgroup_map { 42 const char name[16]; 43 const char kpp[16]; 44 } dhgroup_map[] = { 45 [NVME_AUTH_DHGROUP_NULL] = { 46 .name = "null", .kpp = "null" }, 47 [NVME_AUTH_DHGROUP_2048] = { 48 .name = "ffdhe2048", .kpp = "ffdhe2048(dh)" }, 49 [NVME_AUTH_DHGROUP_3072] = { 50 .name = "ffdhe3072", .kpp = "ffdhe3072(dh)" }, 51 [NVME_AUTH_DHGROUP_4096] = { 52 .name = "ffdhe4096", .kpp = "ffdhe4096(dh)" }, 53 [NVME_AUTH_DHGROUP_6144] = { 54 .name = "ffdhe6144", .kpp = "ffdhe6144(dh)" }, 55 [NVME_AUTH_DHGROUP_8192] = { 56 .name = "ffdhe8192", .kpp = "ffdhe8192(dh)" }, 57 }; 58 59 const char *nvme_auth_dhgroup_name(u8 dhgroup_id) 60 { 61 if (dhgroup_id >= ARRAY_SIZE(dhgroup_map)) 62 return NULL; 63 return dhgroup_map[dhgroup_id].name; 64 } 65 EXPORT_SYMBOL_GPL(nvme_auth_dhgroup_name); 66 67 const char *nvme_auth_dhgroup_kpp(u8 dhgroup_id) 68 { 69 if (dhgroup_id >= ARRAY_SIZE(dhgroup_map)) 70 return NULL; 71 return dhgroup_map[dhgroup_id].kpp; 72 } 73 EXPORT_SYMBOL_GPL(nvme_auth_dhgroup_kpp); 74 75 u8 nvme_auth_dhgroup_id(const char *dhgroup_name) 76 { 77 int i; 78 79 if (!dhgroup_name || !strlen(dhgroup_name)) 80 return NVME_AUTH_DHGROUP_INVALID; 81 for (i = 0; i < ARRAY_SIZE(dhgroup_map); i++) { 82 if (!strlen(dhgroup_map[i].name)) 83 continue; 84 if (!strncmp(dhgroup_map[i].name, dhgroup_name, 85 strlen(dhgroup_map[i].name))) 86 return i; 87 } 88 return NVME_AUTH_DHGROUP_INVALID; 89 } 90 EXPORT_SYMBOL_GPL(nvme_auth_dhgroup_id); 91 92 static struct nvme_dhchap_hash_map { 93 int len; 94 const char hmac[15]; 95 const char digest[8]; 96 } hash_map[] = { 97 [NVME_AUTH_HASH_SHA256] = { 98 .len = 32, 99 .hmac = "hmac(sha256)", 100 .digest = "sha256", 101 }, 102 [NVME_AUTH_HASH_SHA384] = { 103 .len = 48, 104 .hmac = "hmac(sha384)", 105 .digest = "sha384", 106 }, 107 [NVME_AUTH_HASH_SHA512] = { 108 .len = 64, 109 .hmac = "hmac(sha512)", 110 .digest = "sha512", 111 }, 112 }; 113 114 const char *nvme_auth_hmac_name(u8 hmac_id) 115 { 116 if (hmac_id >= ARRAY_SIZE(hash_map)) 117 return NULL; 118 return hash_map[hmac_id].hmac; 119 } 120 EXPORT_SYMBOL_GPL(nvme_auth_hmac_name); 121 122 const char *nvme_auth_digest_name(u8 hmac_id) 123 { 124 if (hmac_id >= ARRAY_SIZE(hash_map)) 125 return NULL; 126 return hash_map[hmac_id].digest; 127 } 128 EXPORT_SYMBOL_GPL(nvme_auth_digest_name); 129 130 u8 nvme_auth_hmac_id(const char *hmac_name) 131 { 132 int i; 133 134 if (!hmac_name || !strlen(hmac_name)) 135 return NVME_AUTH_HASH_INVALID; 136 137 for (i = 0; i < ARRAY_SIZE(hash_map); i++) { 138 if (!strlen(hash_map[i].hmac)) 139 continue; 140 if (!strncmp(hash_map[i].hmac, hmac_name, 141 strlen(hash_map[i].hmac))) 142 return i; 143 } 144 return NVME_AUTH_HASH_INVALID; 145 } 146 EXPORT_SYMBOL_GPL(nvme_auth_hmac_id); 147 148 size_t nvme_auth_hmac_hash_len(u8 hmac_id) 149 { 150 if (hmac_id >= ARRAY_SIZE(hash_map)) 151 return 0; 152 return hash_map[hmac_id].len; 153 } 154 EXPORT_SYMBOL_GPL(nvme_auth_hmac_hash_len); 155 156 u32 nvme_auth_key_struct_size(u32 key_len) 157 { 158 struct nvme_dhchap_key key; 159 160 return struct_size(&key, key, key_len); 161 } 162 EXPORT_SYMBOL_GPL(nvme_auth_key_struct_size); 163 164 struct nvme_dhchap_key *nvme_auth_extract_key(unsigned char *secret, 165 u8 key_hash) 166 { 167 struct nvme_dhchap_key *key; 168 unsigned char *p; 169 u32 crc; 170 int ret, key_len; 171 size_t allocated_len = strlen(secret); 172 173 /* Secret might be affixed with a ':' */ 174 p = strrchr(secret, ':'); 175 if (p) 176 allocated_len = p - secret; 177 key = nvme_auth_alloc_key(allocated_len, 0); 178 if (!key) 179 return ERR_PTR(-ENOMEM); 180 181 key_len = base64_decode(secret, allocated_len, key->key); 182 if (key_len < 0) { 183 pr_debug("base64 key decoding error %d\n", 184 key_len); 185 ret = key_len; 186 goto out_free_secret; 187 } 188 189 if (key_len != 36 && key_len != 52 && 190 key_len != 68) { 191 pr_err("Invalid key len %d\n", key_len); 192 ret = -EINVAL; 193 goto out_free_secret; 194 } 195 196 /* The last four bytes is the CRC in little-endian format */ 197 key_len -= 4; 198 /* 199 * The linux implementation doesn't do pre- and post-increments, 200 * so we have to do it manually. 201 */ 202 crc = ~crc32(~0, key->key, key_len); 203 204 if (get_unaligned_le32(key->key + key_len) != crc) { 205 pr_err("key crc mismatch (key %08x, crc %08x)\n", 206 get_unaligned_le32(key->key + key_len), crc); 207 ret = -EKEYREJECTED; 208 goto out_free_secret; 209 } 210 key->len = key_len; 211 key->hash = key_hash; 212 return key; 213 out_free_secret: 214 nvme_auth_free_key(key); 215 return ERR_PTR(ret); 216 } 217 EXPORT_SYMBOL_GPL(nvme_auth_extract_key); 218 219 struct nvme_dhchap_key *nvme_auth_alloc_key(u32 len, u8 hash) 220 { 221 u32 num_bytes = nvme_auth_key_struct_size(len); 222 struct nvme_dhchap_key *key = kzalloc(num_bytes, GFP_KERNEL); 223 224 if (key) { 225 key->len = len; 226 key->hash = hash; 227 } 228 return key; 229 } 230 EXPORT_SYMBOL_GPL(nvme_auth_alloc_key); 231 232 void nvme_auth_free_key(struct nvme_dhchap_key *key) 233 { 234 if (!key) 235 return; 236 kfree_sensitive(key); 237 } 238 EXPORT_SYMBOL_GPL(nvme_auth_free_key); 239 240 struct nvme_dhchap_key *nvme_auth_transform_key( 241 struct nvme_dhchap_key *key, char *nqn) 242 { 243 const char *hmac_name; 244 struct crypto_shash *key_tfm; 245 SHASH_DESC_ON_STACK(shash, key_tfm); 246 struct nvme_dhchap_key *transformed_key; 247 int ret, key_len; 248 249 if (!key) { 250 pr_warn("No key specified\n"); 251 return ERR_PTR(-ENOKEY); 252 } 253 if (key->hash == 0) { 254 key_len = nvme_auth_key_struct_size(key->len); 255 transformed_key = kmemdup(key, key_len, GFP_KERNEL); 256 if (!transformed_key) 257 return ERR_PTR(-ENOMEM); 258 return transformed_key; 259 } 260 hmac_name = nvme_auth_hmac_name(key->hash); 261 if (!hmac_name) { 262 pr_warn("Invalid key hash id %d\n", key->hash); 263 return ERR_PTR(-EINVAL); 264 } 265 266 key_tfm = crypto_alloc_shash(hmac_name, 0, 0); 267 if (IS_ERR(key_tfm)) 268 return ERR_CAST(key_tfm); 269 270 key_len = crypto_shash_digestsize(key_tfm); 271 transformed_key = nvme_auth_alloc_key(key_len, key->hash); 272 if (!transformed_key) { 273 ret = -ENOMEM; 274 goto out_free_key; 275 } 276 277 shash->tfm = key_tfm; 278 ret = crypto_shash_setkey(key_tfm, key->key, key->len); 279 if (ret < 0) 280 goto out_free_transformed_key; 281 ret = crypto_shash_init(shash); 282 if (ret < 0) 283 goto out_free_transformed_key; 284 ret = crypto_shash_update(shash, nqn, strlen(nqn)); 285 if (ret < 0) 286 goto out_free_transformed_key; 287 ret = crypto_shash_update(shash, "NVMe-over-Fabrics", 17); 288 if (ret < 0) 289 goto out_free_transformed_key; 290 ret = crypto_shash_final(shash, transformed_key->key); 291 if (ret < 0) 292 goto out_free_transformed_key; 293 294 crypto_free_shash(key_tfm); 295 296 return transformed_key; 297 298 out_free_transformed_key: 299 nvme_auth_free_key(transformed_key); 300 out_free_key: 301 crypto_free_shash(key_tfm); 302 303 return ERR_PTR(ret); 304 } 305 EXPORT_SYMBOL_GPL(nvme_auth_transform_key); 306 307 static int nvme_auth_hash_skey(int hmac_id, u8 *skey, size_t skey_len, u8 *hkey) 308 { 309 const char *digest_name; 310 struct crypto_shash *tfm; 311 int ret; 312 313 digest_name = nvme_auth_digest_name(hmac_id); 314 if (!digest_name) { 315 pr_debug("%s: failed to get digest for %d\n", __func__, 316 hmac_id); 317 return -EINVAL; 318 } 319 tfm = crypto_alloc_shash(digest_name, 0, 0); 320 if (IS_ERR(tfm)) 321 return -ENOMEM; 322 323 ret = crypto_shash_tfm_digest(tfm, skey, skey_len, hkey); 324 if (ret < 0) 325 pr_debug("%s: Failed to hash digest len %zu\n", __func__, 326 skey_len); 327 328 crypto_free_shash(tfm); 329 return ret; 330 } 331 332 int nvme_auth_augmented_challenge(u8 hmac_id, u8 *skey, size_t skey_len, 333 u8 *challenge, u8 *aug, size_t hlen) 334 { 335 struct crypto_shash *tfm; 336 u8 *hashed_key; 337 const char *hmac_name; 338 int ret; 339 340 hashed_key = kmalloc(hlen, GFP_KERNEL); 341 if (!hashed_key) 342 return -ENOMEM; 343 344 ret = nvme_auth_hash_skey(hmac_id, skey, 345 skey_len, hashed_key); 346 if (ret < 0) 347 goto out_free_key; 348 349 hmac_name = nvme_auth_hmac_name(hmac_id); 350 if (!hmac_name) { 351 pr_warn("%s: invalid hash algorithm %d\n", 352 __func__, hmac_id); 353 ret = -EINVAL; 354 goto out_free_key; 355 } 356 357 tfm = crypto_alloc_shash(hmac_name, 0, 0); 358 if (IS_ERR(tfm)) { 359 ret = PTR_ERR(tfm); 360 goto out_free_key; 361 } 362 363 ret = crypto_shash_setkey(tfm, hashed_key, hlen); 364 if (ret) 365 goto out_free_hash; 366 367 ret = crypto_shash_tfm_digest(tfm, challenge, hlen, aug); 368 out_free_hash: 369 crypto_free_shash(tfm); 370 out_free_key: 371 kfree_sensitive(hashed_key); 372 return ret; 373 } 374 EXPORT_SYMBOL_GPL(nvme_auth_augmented_challenge); 375 376 int nvme_auth_gen_privkey(struct crypto_kpp *dh_tfm, u8 dh_gid) 377 { 378 int ret; 379 380 ret = crypto_kpp_set_secret(dh_tfm, NULL, 0); 381 if (ret) 382 pr_debug("failed to set private key, error %d\n", ret); 383 384 return ret; 385 } 386 EXPORT_SYMBOL_GPL(nvme_auth_gen_privkey); 387 388 int nvme_auth_gen_pubkey(struct crypto_kpp *dh_tfm, 389 u8 *host_key, size_t host_key_len) 390 { 391 struct kpp_request *req; 392 struct crypto_wait wait; 393 struct scatterlist dst; 394 int ret; 395 396 req = kpp_request_alloc(dh_tfm, GFP_KERNEL); 397 if (!req) 398 return -ENOMEM; 399 400 crypto_init_wait(&wait); 401 kpp_request_set_input(req, NULL, 0); 402 sg_init_one(&dst, host_key, host_key_len); 403 kpp_request_set_output(req, &dst, host_key_len); 404 kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, 405 crypto_req_done, &wait); 406 407 ret = crypto_wait_req(crypto_kpp_generate_public_key(req), &wait); 408 kpp_request_free(req); 409 return ret; 410 } 411 EXPORT_SYMBOL_GPL(nvme_auth_gen_pubkey); 412 413 int nvme_auth_gen_shared_secret(struct crypto_kpp *dh_tfm, 414 u8 *ctrl_key, size_t ctrl_key_len, 415 u8 *sess_key, size_t sess_key_len) 416 { 417 struct kpp_request *req; 418 struct crypto_wait wait; 419 struct scatterlist src, dst; 420 int ret; 421 422 req = kpp_request_alloc(dh_tfm, GFP_KERNEL); 423 if (!req) 424 return -ENOMEM; 425 426 crypto_init_wait(&wait); 427 sg_init_one(&src, ctrl_key, ctrl_key_len); 428 kpp_request_set_input(req, &src, ctrl_key_len); 429 sg_init_one(&dst, sess_key, sess_key_len); 430 kpp_request_set_output(req, &dst, sess_key_len); 431 kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, 432 crypto_req_done, &wait); 433 434 ret = crypto_wait_req(crypto_kpp_compute_shared_secret(req), &wait); 435 436 kpp_request_free(req); 437 return ret; 438 } 439 EXPORT_SYMBOL_GPL(nvme_auth_gen_shared_secret); 440 441 int nvme_auth_generate_key(u8 *secret, struct nvme_dhchap_key **ret_key) 442 { 443 struct nvme_dhchap_key *key; 444 u8 key_hash; 445 446 if (!secret) { 447 *ret_key = NULL; 448 return 0; 449 } 450 451 if (sscanf(secret, "DHHC-1:%hhd:%*s:", &key_hash) != 1) 452 return -EINVAL; 453 454 /* Pass in the secret without the 'DHHC-1:XX:' prefix */ 455 key = nvme_auth_extract_key(secret + 10, key_hash); 456 if (IS_ERR(key)) { 457 *ret_key = NULL; 458 return PTR_ERR(key); 459 } 460 461 *ret_key = key; 462 return 0; 463 } 464 EXPORT_SYMBOL_GPL(nvme_auth_generate_key); 465 466 /** 467 * nvme_auth_generate_psk - Generate a PSK for TLS 468 * @hmac_id: Hash function identifier 469 * @skey: Session key 470 * @skey_len: Length of @skey 471 * @c1: Value of challenge C1 472 * @c2: Value of challenge C2 473 * @hash_len: Hash length of the hash algorithm 474 * @ret_psk: Pointer to the resulting generated PSK 475 * @ret_len: length of @ret_psk 476 * 477 * Generate a PSK for TLS as specified in NVMe base specification, section 478 * 8.13.5.9: Generated PSK for TLS 479 * 480 * The generated PSK for TLS shall be computed applying the HMAC function 481 * using the hash function H( ) selected by the HashID parameter in the 482 * DH-HMAC-CHAP_Challenge message with the session key KS as key to the 483 * concatenation of the two challenges C1 and C2 (i.e., generated 484 * PSK = HMAC(KS, C1 || C2)). 485 * 486 * Returns 0 on success with a valid generated PSK pointer in @ret_psk and 487 * the length of @ret_psk in @ret_len, or a negative error number otherwise. 488 */ 489 int nvme_auth_generate_psk(u8 hmac_id, u8 *skey, size_t skey_len, 490 u8 *c1, u8 *c2, size_t hash_len, u8 **ret_psk, size_t *ret_len) 491 { 492 struct crypto_shash *tfm; 493 SHASH_DESC_ON_STACK(shash, tfm); 494 u8 *psk; 495 const char *hmac_name; 496 int ret, psk_len; 497 498 if (!c1 || !c2) 499 return -EINVAL; 500 501 hmac_name = nvme_auth_hmac_name(hmac_id); 502 if (!hmac_name) { 503 pr_warn("%s: invalid hash algorithm %d\n", 504 __func__, hmac_id); 505 return -EINVAL; 506 } 507 508 tfm = crypto_alloc_shash(hmac_name, 0, 0); 509 if (IS_ERR(tfm)) 510 return PTR_ERR(tfm); 511 512 psk_len = crypto_shash_digestsize(tfm); 513 psk = kzalloc(psk_len, GFP_KERNEL); 514 if (!psk) { 515 ret = -ENOMEM; 516 goto out_free_tfm; 517 } 518 519 shash->tfm = tfm; 520 ret = crypto_shash_setkey(tfm, skey, skey_len); 521 if (ret) 522 goto out_free_psk; 523 524 ret = crypto_shash_init(shash); 525 if (ret) 526 goto out_free_psk; 527 528 ret = crypto_shash_update(shash, c1, hash_len); 529 if (ret) 530 goto out_free_psk; 531 532 ret = crypto_shash_update(shash, c2, hash_len); 533 if (ret) 534 goto out_free_psk; 535 536 ret = crypto_shash_final(shash, psk); 537 if (!ret) { 538 *ret_psk = psk; 539 *ret_len = psk_len; 540 } 541 542 out_free_psk: 543 if (ret) 544 kfree_sensitive(psk); 545 out_free_tfm: 546 crypto_free_shash(tfm); 547 548 return ret; 549 } 550 EXPORT_SYMBOL_GPL(nvme_auth_generate_psk); 551 552 /** 553 * nvme_auth_generate_digest - Generate TLS PSK digest 554 * @hmac_id: Hash function identifier 555 * @psk: Generated input PSK 556 * @psk_len: Length of @psk 557 * @subsysnqn: NQN of the subsystem 558 * @hostnqn: NQN of the host 559 * @ret_digest: Pointer to the returned digest 560 * 561 * Generate a TLS PSK digest as specified in TP8018 Section 3.6.1.3: 562 * TLS PSK and PSK identity Derivation 563 * 564 * The PSK digest shall be computed by encoding in Base64 (refer to RFC 565 * 4648) the result of the application of the HMAC function using the hash 566 * function specified in item 4 above (ie the hash function of the cipher 567 * suite associated with the PSK identity) with the PSK as HMAC key to the 568 * concatenation of: 569 * - the NQN of the host (i.e., NQNh) not including the null terminator; 570 * - a space character; 571 * - the NQN of the NVM subsystem (i.e., NQNc) not including the null 572 * terminator; 573 * - a space character; and 574 * - the seventeen ASCII characters "NVMe-over-Fabrics" 575 * (i.e., <PSK digest> = Base64(HMAC(PSK, NQNh || " " || NQNc || " " || 576 * "NVMe-over-Fabrics"))). 577 * The length of the PSK digest depends on the hash function used to compute 578 * it as follows: 579 * - If the SHA-256 hash function is used, the resulting PSK digest is 44 580 * characters long; or 581 * - If the SHA-384 hash function is used, the resulting PSK digest is 64 582 * characters long. 583 * 584 * Returns 0 on success with a valid digest pointer in @ret_digest, or a 585 * negative error number on failure. 586 */ 587 int nvme_auth_generate_digest(u8 hmac_id, u8 *psk, size_t psk_len, 588 char *subsysnqn, char *hostnqn, u8 **ret_digest) 589 { 590 struct crypto_shash *tfm; 591 SHASH_DESC_ON_STACK(shash, tfm); 592 u8 *digest, *enc; 593 const char *hmac_name; 594 size_t digest_len, hmac_len; 595 int ret; 596 597 if (WARN_ON(!subsysnqn || !hostnqn)) 598 return -EINVAL; 599 600 hmac_name = nvme_auth_hmac_name(hmac_id); 601 if (!hmac_name) { 602 pr_warn("%s: invalid hash algorithm %d\n", 603 __func__, hmac_id); 604 return -EINVAL; 605 } 606 607 switch (nvme_auth_hmac_hash_len(hmac_id)) { 608 case 32: 609 hmac_len = 44; 610 break; 611 case 48: 612 hmac_len = 64; 613 break; 614 default: 615 pr_warn("%s: invalid hash algorithm '%s'\n", 616 __func__, hmac_name); 617 return -EINVAL; 618 } 619 620 enc = kzalloc(hmac_len + 1, GFP_KERNEL); 621 if (!enc) 622 return -ENOMEM; 623 624 tfm = crypto_alloc_shash(hmac_name, 0, 0); 625 if (IS_ERR(tfm)) { 626 ret = PTR_ERR(tfm); 627 goto out_free_enc; 628 } 629 630 digest_len = crypto_shash_digestsize(tfm); 631 digest = kzalloc(digest_len, GFP_KERNEL); 632 if (!digest) { 633 ret = -ENOMEM; 634 goto out_free_tfm; 635 } 636 637 shash->tfm = tfm; 638 ret = crypto_shash_setkey(tfm, psk, psk_len); 639 if (ret) 640 goto out_free_digest; 641 642 ret = crypto_shash_init(shash); 643 if (ret) 644 goto out_free_digest; 645 646 ret = crypto_shash_update(shash, hostnqn, strlen(hostnqn)); 647 if (ret) 648 goto out_free_digest; 649 650 ret = crypto_shash_update(shash, " ", 1); 651 if (ret) 652 goto out_free_digest; 653 654 ret = crypto_shash_update(shash, subsysnqn, strlen(subsysnqn)); 655 if (ret) 656 goto out_free_digest; 657 658 ret = crypto_shash_update(shash, " NVMe-over-Fabrics", 18); 659 if (ret) 660 goto out_free_digest; 661 662 ret = crypto_shash_final(shash, digest); 663 if (ret) 664 goto out_free_digest; 665 666 ret = base64_encode(digest, digest_len, enc); 667 if (ret < hmac_len) { 668 ret = -ENOKEY; 669 goto out_free_digest; 670 } 671 *ret_digest = enc; 672 ret = 0; 673 674 out_free_digest: 675 kfree_sensitive(digest); 676 out_free_tfm: 677 crypto_free_shash(tfm); 678 out_free_enc: 679 if (ret) 680 kfree_sensitive(enc); 681 682 return ret; 683 } 684 EXPORT_SYMBOL_GPL(nvme_auth_generate_digest); 685 686 /** 687 * nvme_auth_derive_tls_psk - Derive TLS PSK 688 * @hmac_id: Hash function identifier 689 * @psk: generated input PSK 690 * @psk_len: size of @psk 691 * @psk_digest: TLS PSK digest 692 * @ret_psk: Pointer to the resulting TLS PSK 693 * 694 * Derive a TLS PSK as specified in TP8018 Section 3.6.1.3: 695 * TLS PSK and PSK identity Derivation 696 * 697 * The TLS PSK shall be derived as follows from an input PSK 698 * (i.e., either a retained PSK or a generated PSK) and a PSK 699 * identity using the HKDF-Extract and HKDF-Expand-Label operations 700 * (refer to RFC 5869 and RFC 8446) where the hash function is the 701 * one specified by the hash specifier of the PSK identity: 702 * 1. PRK = HKDF-Extract(0, Input PSK); and 703 * 2. TLS PSK = HKDF-Expand-Label(PRK, "nvme-tls-psk", PskIdentityContext, L), 704 * where PskIdentityContext is the hash identifier indicated in 705 * the PSK identity concatenated to a space character and to the 706 * Base64 PSK digest (i.e., "<hash> <PSK digest>") and L is the 707 * output size in bytes of the hash function (i.e., 32 for SHA-256 708 * and 48 for SHA-384). 709 * 710 * Returns 0 on success with a valid psk pointer in @ret_psk or a negative 711 * error number otherwise. 712 */ 713 int nvme_auth_derive_tls_psk(int hmac_id, u8 *psk, size_t psk_len, 714 u8 *psk_digest, u8 **ret_psk) 715 { 716 struct crypto_shash *hmac_tfm; 717 const char *hmac_name; 718 const char *psk_prefix = "tls13 nvme-tls-psk"; 719 static const char default_salt[HKDF_MAX_HASHLEN]; 720 size_t info_len, prk_len; 721 char *info; 722 unsigned char *prk, *tls_key; 723 int ret; 724 725 hmac_name = nvme_auth_hmac_name(hmac_id); 726 if (!hmac_name) { 727 pr_warn("%s: invalid hash algorithm %d\n", 728 __func__, hmac_id); 729 return -EINVAL; 730 } 731 if (hmac_id == NVME_AUTH_HASH_SHA512) { 732 pr_warn("%s: unsupported hash algorithm %s\n", 733 __func__, hmac_name); 734 return -EINVAL; 735 } 736 737 hmac_tfm = crypto_alloc_shash(hmac_name, 0, 0); 738 if (IS_ERR(hmac_tfm)) 739 return PTR_ERR(hmac_tfm); 740 741 prk_len = crypto_shash_digestsize(hmac_tfm); 742 prk = kzalloc(prk_len, GFP_KERNEL); 743 if (!prk) { 744 ret = -ENOMEM; 745 goto out_free_shash; 746 } 747 748 if (WARN_ON(prk_len > HKDF_MAX_HASHLEN)) { 749 ret = -EINVAL; 750 goto out_free_prk; 751 } 752 ret = hkdf_extract(hmac_tfm, psk, psk_len, 753 default_salt, prk_len, prk); 754 if (ret) 755 goto out_free_prk; 756 757 ret = crypto_shash_setkey(hmac_tfm, prk, prk_len); 758 if (ret) 759 goto out_free_prk; 760 761 /* 762 * 2 additional bytes for the length field from HDKF-Expand-Label, 763 * 2 additional bytes for the HMAC ID, and one byte for the space 764 * separator. 765 */ 766 info_len = strlen(psk_digest) + strlen(psk_prefix) + 5; 767 info = kzalloc(info_len + 1, GFP_KERNEL); 768 if (!info) { 769 ret = -ENOMEM; 770 goto out_free_prk; 771 } 772 773 put_unaligned_be16(psk_len, info); 774 memcpy(info + 2, psk_prefix, strlen(psk_prefix)); 775 sprintf(info + 2 + strlen(psk_prefix), "%02d %s", hmac_id, psk_digest); 776 777 tls_key = kzalloc(psk_len, GFP_KERNEL); 778 if (!tls_key) { 779 ret = -ENOMEM; 780 goto out_free_info; 781 } 782 ret = hkdf_expand(hmac_tfm, info, info_len, tls_key, psk_len); 783 if (ret) { 784 kfree(tls_key); 785 goto out_free_info; 786 } 787 *ret_psk = tls_key; 788 789 out_free_info: 790 kfree(info); 791 out_free_prk: 792 kfree(prk); 793 out_free_shash: 794 crypto_free_shash(hmac_tfm); 795 796 return ret; 797 } 798 EXPORT_SYMBOL_GPL(nvme_auth_derive_tls_psk); 799 800 MODULE_DESCRIPTION("NVMe Authentication framework"); 801 MODULE_LICENSE("GPL v2"); 802