1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2004 IBM Corporation 4 * Copyright (C) 2014 Intel Corporation 5 */ 6 7 #include <linux/asn1_encoder.h> 8 #include <linux/oid_registry.h> 9 #include <linux/string.h> 10 #include <linux/err.h> 11 #include <linux/tpm.h> 12 #include <linux/tpm_command.h> 13 14 #include <keys/trusted-type.h> 15 #include <keys/trusted_tpm.h> 16 17 #include <asm/unaligned.h> 18 19 #include "tpm2key.asn1.h" 20 21 static struct tpm2_hash tpm2_hash_map[] = { 22 {HASH_ALGO_SHA1, TPM_ALG_SHA1}, 23 {HASH_ALGO_SHA256, TPM_ALG_SHA256}, 24 {HASH_ALGO_SHA384, TPM_ALG_SHA384}, 25 {HASH_ALGO_SHA512, TPM_ALG_SHA512}, 26 {HASH_ALGO_SM3_256, TPM_ALG_SM3_256}, 27 }; 28 29 static u32 tpm2key_oid[] = { 2, 23, 133, 10, 1, 5 }; 30 31 static int tpm2_key_encode(struct trusted_key_payload *payload, 32 struct trusted_key_options *options, 33 u8 *src, u32 len) 34 { 35 const int SCRATCH_SIZE = PAGE_SIZE; 36 u8 *scratch = kmalloc(SCRATCH_SIZE, GFP_KERNEL); 37 u8 *work = scratch, *work1; 38 u8 *end_work = scratch + SCRATCH_SIZE; 39 u8 *priv, *pub; 40 u16 priv_len, pub_len; 41 42 priv_len = get_unaligned_be16(src) + 2; 43 priv = src; 44 45 src += priv_len; 46 47 pub_len = get_unaligned_be16(src) + 2; 48 pub = src; 49 50 if (!scratch) 51 return -ENOMEM; 52 53 work = asn1_encode_oid(work, end_work, tpm2key_oid, 54 asn1_oid_len(tpm2key_oid)); 55 56 if (options->blobauth_len == 0) { 57 unsigned char bool[3], *w = bool; 58 /* tag 0 is emptyAuth */ 59 w = asn1_encode_boolean(w, w + sizeof(bool), true); 60 if (WARN(IS_ERR(w), "BUG: Boolean failed to encode")) 61 return PTR_ERR(w); 62 work = asn1_encode_tag(work, end_work, 0, bool, w - bool); 63 } 64 65 /* 66 * Assume both octet strings will encode to a 2 byte definite length 67 * 68 * Note: For a well behaved TPM, this warning should never 69 * trigger, so if it does there's something nefarious going on 70 */ 71 if (WARN(work - scratch + pub_len + priv_len + 14 > SCRATCH_SIZE, 72 "BUG: scratch buffer is too small")) 73 return -EINVAL; 74 75 work = asn1_encode_integer(work, end_work, options->keyhandle); 76 work = asn1_encode_octet_string(work, end_work, pub, pub_len); 77 work = asn1_encode_octet_string(work, end_work, priv, priv_len); 78 79 work1 = payload->blob; 80 work1 = asn1_encode_sequence(work1, work1 + sizeof(payload->blob), 81 scratch, work - scratch); 82 if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed")) 83 return PTR_ERR(work1); 84 85 return work1 - payload->blob; 86 } 87 88 struct tpm2_key_context { 89 u32 parent; 90 const u8 *pub; 91 u32 pub_len; 92 const u8 *priv; 93 u32 priv_len; 94 }; 95 96 static int tpm2_key_decode(struct trusted_key_payload *payload, 97 struct trusted_key_options *options, 98 u8 **buf) 99 { 100 int ret; 101 struct tpm2_key_context ctx; 102 u8 *blob; 103 104 memset(&ctx, 0, sizeof(ctx)); 105 106 ret = asn1_ber_decoder(&tpm2key_decoder, &ctx, payload->blob, 107 payload->blob_len); 108 if (ret < 0) 109 return ret; 110 111 if (ctx.priv_len + ctx.pub_len > MAX_BLOB_SIZE) 112 return -EINVAL; 113 114 blob = kmalloc(ctx.priv_len + ctx.pub_len + 4, GFP_KERNEL); 115 if (!blob) 116 return -ENOMEM; 117 118 *buf = blob; 119 options->keyhandle = ctx.parent; 120 121 memcpy(blob, ctx.priv, ctx.priv_len); 122 blob += ctx.priv_len; 123 124 memcpy(blob, ctx.pub, ctx.pub_len); 125 126 return 0; 127 } 128 129 int tpm2_key_parent(void *context, size_t hdrlen, 130 unsigned char tag, 131 const void *value, size_t vlen) 132 { 133 struct tpm2_key_context *ctx = context; 134 const u8 *v = value; 135 int i; 136 137 ctx->parent = 0; 138 for (i = 0; i < vlen; i++) { 139 ctx->parent <<= 8; 140 ctx->parent |= v[i]; 141 } 142 143 return 0; 144 } 145 146 int tpm2_key_type(void *context, size_t hdrlen, 147 unsigned char tag, 148 const void *value, size_t vlen) 149 { 150 enum OID oid = look_up_OID(value, vlen); 151 152 if (oid != OID_TPMSealedData) { 153 char buffer[50]; 154 155 sprint_oid(value, vlen, buffer, sizeof(buffer)); 156 pr_debug("OID is \"%s\" which is not TPMSealedData\n", 157 buffer); 158 return -EINVAL; 159 } 160 161 return 0; 162 } 163 164 int tpm2_key_pub(void *context, size_t hdrlen, 165 unsigned char tag, 166 const void *value, size_t vlen) 167 { 168 struct tpm2_key_context *ctx = context; 169 170 ctx->pub = value; 171 ctx->pub_len = vlen; 172 173 return 0; 174 } 175 176 int tpm2_key_priv(void *context, size_t hdrlen, 177 unsigned char tag, 178 const void *value, size_t vlen) 179 { 180 struct tpm2_key_context *ctx = context; 181 182 ctx->priv = value; 183 ctx->priv_len = vlen; 184 185 return 0; 186 } 187 188 /** 189 * tpm2_buf_append_auth() - append TPMS_AUTH_COMMAND to the buffer. 190 * 191 * @buf: an allocated tpm_buf instance 192 * @session_handle: session handle 193 * @nonce: the session nonce, may be NULL if not used 194 * @nonce_len: the session nonce length, may be 0 if not used 195 * @attributes: the session attributes 196 * @hmac: the session HMAC or password, may be NULL if not used 197 * @hmac_len: the session HMAC or password length, maybe 0 if not used 198 */ 199 static void tpm2_buf_append_auth(struct tpm_buf *buf, u32 session_handle, 200 const u8 *nonce, u16 nonce_len, 201 u8 attributes, 202 const u8 *hmac, u16 hmac_len) 203 { 204 tpm_buf_append_u32(buf, 9 + nonce_len + hmac_len); 205 tpm_buf_append_u32(buf, session_handle); 206 tpm_buf_append_u16(buf, nonce_len); 207 208 if (nonce && nonce_len) 209 tpm_buf_append(buf, nonce, nonce_len); 210 211 tpm_buf_append_u8(buf, attributes); 212 tpm_buf_append_u16(buf, hmac_len); 213 214 if (hmac && hmac_len) 215 tpm_buf_append(buf, hmac, hmac_len); 216 } 217 218 /** 219 * tpm2_seal_trusted() - seal the payload of a trusted key 220 * 221 * @chip: TPM chip to use 222 * @payload: the key data in clear and encrypted form 223 * @options: authentication values and other options 224 * 225 * Return: < 0 on error and 0 on success. 226 */ 227 int tpm2_seal_trusted(struct tpm_chip *chip, 228 struct trusted_key_payload *payload, 229 struct trusted_key_options *options) 230 { 231 off_t offset = TPM_HEADER_SIZE; 232 struct tpm_buf buf, sized; 233 int blob_len = 0; 234 u32 hash; 235 u32 flags; 236 int i; 237 int rc; 238 239 for (i = 0; i < ARRAY_SIZE(tpm2_hash_map); i++) { 240 if (options->hash == tpm2_hash_map[i].crypto_id) { 241 hash = tpm2_hash_map[i].tpm_id; 242 break; 243 } 244 } 245 246 if (i == ARRAY_SIZE(tpm2_hash_map)) 247 return -EINVAL; 248 249 if (!options->keyhandle) 250 return -EINVAL; 251 252 rc = tpm_try_get_ops(chip); 253 if (rc) 254 return rc; 255 256 rc = tpm2_start_auth_session(chip); 257 if (rc) 258 goto out_put; 259 260 rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE); 261 if (rc) { 262 tpm2_end_auth_session(chip); 263 goto out_put; 264 } 265 266 rc = tpm_buf_init_sized(&sized); 267 if (rc) { 268 tpm_buf_destroy(&buf); 269 tpm2_end_auth_session(chip); 270 goto out_put; 271 } 272 273 tpm_buf_append_name(chip, &buf, options->keyhandle, NULL); 274 tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_DECRYPT, 275 options->keyauth, TPM_DIGEST_SIZE); 276 277 /* sensitive */ 278 tpm_buf_append_u16(&sized, options->blobauth_len); 279 280 if (options->blobauth_len) 281 tpm_buf_append(&sized, options->blobauth, options->blobauth_len); 282 283 tpm_buf_append_u16(&sized, payload->key_len); 284 tpm_buf_append(&sized, payload->key, payload->key_len); 285 tpm_buf_append(&buf, sized.data, sized.length); 286 287 /* public */ 288 tpm_buf_reset_sized(&sized); 289 tpm_buf_append_u16(&sized, TPM_ALG_KEYEDHASH); 290 tpm_buf_append_u16(&sized, hash); 291 292 /* key properties */ 293 flags = 0; 294 flags |= options->policydigest_len ? 0 : TPM2_OA_USER_WITH_AUTH; 295 flags |= payload->migratable ? 0 : (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT); 296 tpm_buf_append_u32(&sized, flags); 297 298 /* policy */ 299 tpm_buf_append_u16(&sized, options->policydigest_len); 300 if (options->policydigest_len) 301 tpm_buf_append(&sized, options->policydigest, options->policydigest_len); 302 303 /* public parameters */ 304 tpm_buf_append_u16(&sized, TPM_ALG_NULL); 305 tpm_buf_append_u16(&sized, 0); 306 307 tpm_buf_append(&buf, sized.data, sized.length); 308 309 /* outside info */ 310 tpm_buf_append_u16(&buf, 0); 311 312 /* creation PCR */ 313 tpm_buf_append_u32(&buf, 0); 314 315 if (buf.flags & TPM_BUF_OVERFLOW) { 316 rc = -E2BIG; 317 tpm2_end_auth_session(chip); 318 goto out; 319 } 320 321 tpm_buf_fill_hmac_session(chip, &buf); 322 rc = tpm_transmit_cmd(chip, &buf, 4, "sealing data"); 323 rc = tpm_buf_check_hmac_response(chip, &buf, rc); 324 if (rc) 325 goto out; 326 327 blob_len = tpm_buf_read_u32(&buf, &offset); 328 if (blob_len > MAX_BLOB_SIZE || buf.flags & TPM_BUF_BOUNDARY_ERROR) { 329 rc = -E2BIG; 330 goto out; 331 } 332 if (buf.length - offset < blob_len) { 333 rc = -EFAULT; 334 goto out; 335 } 336 337 blob_len = tpm2_key_encode(payload, options, &buf.data[offset], blob_len); 338 339 out: 340 tpm_buf_destroy(&sized); 341 tpm_buf_destroy(&buf); 342 343 if (rc > 0) { 344 if (tpm2_rc_value(rc) == TPM2_RC_HASH) 345 rc = -EINVAL; 346 else 347 rc = -EPERM; 348 } 349 if (blob_len < 0) 350 rc = blob_len; 351 else 352 payload->blob_len = blob_len; 353 354 out_put: 355 tpm_put_ops(chip); 356 return rc; 357 } 358 359 /** 360 * tpm2_load_cmd() - execute a TPM2_Load command 361 * 362 * @chip: TPM chip to use 363 * @payload: the key data in clear and encrypted form 364 * @options: authentication values and other options 365 * @blob_handle: returned blob handle 366 * 367 * Return: 0 on success. 368 * -E2BIG on wrong payload size. 369 * -EPERM on tpm error status. 370 * < 0 error from tpm_send. 371 */ 372 static int tpm2_load_cmd(struct tpm_chip *chip, 373 struct trusted_key_payload *payload, 374 struct trusted_key_options *options, 375 u32 *blob_handle) 376 { 377 struct tpm_buf buf; 378 unsigned int private_len; 379 unsigned int public_len; 380 unsigned int blob_len; 381 u8 *blob, *pub; 382 int rc; 383 u32 attrs; 384 385 rc = tpm2_key_decode(payload, options, &blob); 386 if (rc) { 387 /* old form */ 388 blob = payload->blob; 389 payload->old_format = 1; 390 } 391 392 /* new format carries keyhandle but old format doesn't */ 393 if (!options->keyhandle) 394 return -EINVAL; 395 396 /* must be big enough for at least the two be16 size counts */ 397 if (payload->blob_len < 4) 398 return -EINVAL; 399 400 private_len = get_unaligned_be16(blob); 401 402 /* must be big enough for following public_len */ 403 if (private_len + 2 + 2 > (payload->blob_len)) 404 return -E2BIG; 405 406 public_len = get_unaligned_be16(blob + 2 + private_len); 407 if (private_len + 2 + public_len + 2 > payload->blob_len) 408 return -E2BIG; 409 410 pub = blob + 2 + private_len + 2; 411 /* key attributes are always at offset 4 */ 412 attrs = get_unaligned_be32(pub + 4); 413 414 if ((attrs & (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT)) == 415 (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT)) 416 payload->migratable = 0; 417 else 418 payload->migratable = 1; 419 420 blob_len = private_len + public_len + 4; 421 if (blob_len > payload->blob_len) 422 return -E2BIG; 423 424 rc = tpm2_start_auth_session(chip); 425 if (rc) 426 return rc; 427 428 rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD); 429 if (rc) { 430 tpm2_end_auth_session(chip); 431 return rc; 432 } 433 434 tpm_buf_append_name(chip, &buf, options->keyhandle, NULL); 435 tpm_buf_append_hmac_session(chip, &buf, 0, options->keyauth, 436 TPM_DIGEST_SIZE); 437 438 tpm_buf_append(&buf, blob, blob_len); 439 440 if (buf.flags & TPM_BUF_OVERFLOW) { 441 rc = -E2BIG; 442 tpm2_end_auth_session(chip); 443 goto out; 444 } 445 446 tpm_buf_fill_hmac_session(chip, &buf); 447 rc = tpm_transmit_cmd(chip, &buf, 4, "loading blob"); 448 rc = tpm_buf_check_hmac_response(chip, &buf, rc); 449 if (!rc) 450 *blob_handle = be32_to_cpup( 451 (__be32 *) &buf.data[TPM_HEADER_SIZE]); 452 453 out: 454 if (blob != payload->blob) 455 kfree(blob); 456 tpm_buf_destroy(&buf); 457 458 if (rc > 0) 459 rc = -EPERM; 460 461 return rc; 462 } 463 464 /** 465 * tpm2_unseal_cmd() - execute a TPM2_Unload command 466 * 467 * @chip: TPM chip to use 468 * @payload: the key data in clear and encrypted form 469 * @options: authentication values and other options 470 * @blob_handle: blob handle 471 * 472 * Return: 0 on success 473 * -EPERM on tpm error status 474 * < 0 error from tpm_send 475 */ 476 static int tpm2_unseal_cmd(struct tpm_chip *chip, 477 struct trusted_key_payload *payload, 478 struct trusted_key_options *options, 479 u32 blob_handle) 480 { 481 struct tpm_buf buf; 482 u16 data_len; 483 u8 *data; 484 int rc; 485 486 rc = tpm2_start_auth_session(chip); 487 if (rc) 488 return rc; 489 490 rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL); 491 if (rc) { 492 tpm2_end_auth_session(chip); 493 return rc; 494 } 495 496 tpm_buf_append_name(chip, &buf, blob_handle, NULL); 497 498 if (!options->policyhandle) { 499 tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT, 500 options->blobauth, 501 options->blobauth_len); 502 } else { 503 /* 504 * FIXME: The policy session was generated outside the 505 * kernel so we don't known the nonce and thus can't 506 * calculate a HMAC on it. Therefore, the user can 507 * only really use TPM2_PolicyPassword and we must 508 * send down the plain text password, which could be 509 * intercepted. We can still encrypt the returned 510 * key, but that's small comfort since the interposer 511 * could repeat our actions with the exfiltrated 512 * password. 513 */ 514 tpm2_buf_append_auth(&buf, options->policyhandle, 515 NULL /* nonce */, 0, 0, 516 options->blobauth, options->blobauth_len); 517 tpm_buf_append_hmac_session_opt(chip, &buf, TPM2_SA_ENCRYPT, 518 NULL, 0); 519 } 520 521 tpm_buf_fill_hmac_session(chip, &buf); 522 rc = tpm_transmit_cmd(chip, &buf, 6, "unsealing"); 523 rc = tpm_buf_check_hmac_response(chip, &buf, rc); 524 if (rc > 0) 525 rc = -EPERM; 526 527 if (!rc) { 528 data_len = be16_to_cpup( 529 (__be16 *) &buf.data[TPM_HEADER_SIZE + 4]); 530 if (data_len < MIN_KEY_SIZE || data_len > MAX_KEY_SIZE) { 531 rc = -EFAULT; 532 goto out; 533 } 534 535 if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + 6 + data_len) { 536 rc = -EFAULT; 537 goto out; 538 } 539 data = &buf.data[TPM_HEADER_SIZE + 6]; 540 541 if (payload->old_format) { 542 /* migratable flag is at the end of the key */ 543 memcpy(payload->key, data, data_len - 1); 544 payload->key_len = data_len - 1; 545 payload->migratable = data[data_len - 1]; 546 } else { 547 /* 548 * migratable flag already collected from key 549 * attributes 550 */ 551 memcpy(payload->key, data, data_len); 552 payload->key_len = data_len; 553 } 554 } 555 556 out: 557 tpm_buf_destroy(&buf); 558 return rc; 559 } 560 561 /** 562 * tpm2_unseal_trusted() - unseal the payload of a trusted key 563 * 564 * @chip: TPM chip to use 565 * @payload: the key data in clear and encrypted form 566 * @options: authentication values and other options 567 * 568 * Return: Same as with tpm_send. 569 */ 570 int tpm2_unseal_trusted(struct tpm_chip *chip, 571 struct trusted_key_payload *payload, 572 struct trusted_key_options *options) 573 { 574 u32 blob_handle; 575 int rc; 576 577 rc = tpm_try_get_ops(chip); 578 if (rc) 579 return rc; 580 581 rc = tpm2_load_cmd(chip, payload, options, &blob_handle); 582 if (rc) 583 goto out; 584 585 rc = tpm2_unseal_cmd(chip, payload, options, blob_handle); 586 tpm2_flush_context(chip, blob_handle); 587 588 out: 589 tpm_put_ops(chip); 590 591 return rc; 592 } 593