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 <linux/unaligned.h> 18 19 #include "tpm2key.asn1.h" 20 21 static u32 tpm2key_oid[] = { 2, 23, 133, 10, 1, 5 }; 22 23 static int tpm2_key_encode(struct trusted_key_payload *payload, 24 struct trusted_key_options *options, 25 u8 *src, u32 len) 26 { 27 const int SCRATCH_SIZE = PAGE_SIZE; 28 u8 *scratch = kmalloc(SCRATCH_SIZE, GFP_KERNEL); 29 u8 *work = scratch, *work1; 30 u8 *end_work = scratch + SCRATCH_SIZE; 31 u8 *priv, *pub; 32 u16 priv_len, pub_len; 33 int ret; 34 35 priv_len = get_unaligned_be16(src) + 2; 36 priv = src; 37 38 src += priv_len; 39 40 pub_len = get_unaligned_be16(src) + 2; 41 pub = src; 42 43 if (!scratch) 44 return -ENOMEM; 45 46 work = asn1_encode_oid(work, end_work, tpm2key_oid, 47 asn1_oid_len(tpm2key_oid)); 48 49 if (options->blobauth_len == 0) { 50 unsigned char bool[3], *w = bool; 51 /* tag 0 is emptyAuth */ 52 w = asn1_encode_boolean(w, w + sizeof(bool), true); 53 if (WARN(IS_ERR(w), "BUG: Boolean failed to encode")) { 54 ret = PTR_ERR(w); 55 goto err; 56 } 57 work = asn1_encode_tag(work, end_work, 0, bool, w - bool); 58 } 59 60 /* 61 * Assume both octet strings will encode to a 2 byte definite length 62 * 63 * Note: For a well behaved TPM, this warning should never 64 * trigger, so if it does there's something nefarious going on 65 */ 66 if (WARN(work - scratch + pub_len + priv_len + 14 > SCRATCH_SIZE, 67 "BUG: scratch buffer is too small")) { 68 ret = -EINVAL; 69 goto err; 70 } 71 72 work = asn1_encode_integer(work, end_work, options->keyhandle); 73 work = asn1_encode_octet_string(work, end_work, pub, pub_len); 74 work = asn1_encode_octet_string(work, end_work, priv, priv_len); 75 76 work1 = payload->blob; 77 work1 = asn1_encode_sequence(work1, work1 + sizeof(payload->blob), 78 scratch, work - scratch); 79 if (IS_ERR(work1)) { 80 ret = PTR_ERR(work1); 81 pr_err("BUG: ASN.1 encoder failed with %d\n", ret); 82 goto err; 83 } 84 85 kfree(scratch); 86 return work1 - payload->blob; 87 88 err: 89 kfree(scratch); 90 return ret; 91 } 92 93 struct tpm2_key_context { 94 u32 parent; 95 const u8 *pub; 96 u32 pub_len; 97 const u8 *priv; 98 u32 priv_len; 99 }; 100 101 static int tpm2_key_decode(struct trusted_key_payload *payload, 102 struct trusted_key_options *options, 103 u8 **buf) 104 { 105 int ret; 106 struct tpm2_key_context ctx; 107 u8 *blob; 108 109 memset(&ctx, 0, sizeof(ctx)); 110 111 ret = asn1_ber_decoder(&tpm2key_decoder, &ctx, payload->blob, 112 payload->blob_len); 113 if (ret < 0) 114 return ret; 115 116 if (ctx.priv_len + ctx.pub_len > MAX_BLOB_SIZE) 117 return -EINVAL; 118 119 blob = kmalloc(ctx.priv_len + ctx.pub_len + 4, GFP_KERNEL); 120 if (!blob) 121 return -ENOMEM; 122 123 *buf = blob; 124 options->keyhandle = ctx.parent; 125 126 memcpy(blob, ctx.priv, ctx.priv_len); 127 blob += ctx.priv_len; 128 129 memcpy(blob, ctx.pub, ctx.pub_len); 130 131 return 0; 132 } 133 134 int tpm2_key_parent(void *context, size_t hdrlen, 135 unsigned char tag, 136 const void *value, size_t vlen) 137 { 138 struct tpm2_key_context *ctx = context; 139 const u8 *v = value; 140 int i; 141 142 ctx->parent = 0; 143 for (i = 0; i < vlen; i++) { 144 ctx->parent <<= 8; 145 ctx->parent |= v[i]; 146 } 147 148 return 0; 149 } 150 151 int tpm2_key_type(void *context, size_t hdrlen, 152 unsigned char tag, 153 const void *value, size_t vlen) 154 { 155 enum OID oid = look_up_OID(value, vlen); 156 157 if (oid != OID_TPMSealedData) { 158 char buffer[50]; 159 160 sprint_oid(value, vlen, buffer, sizeof(buffer)); 161 pr_debug("OID is \"%s\" which is not TPMSealedData\n", 162 buffer); 163 return -EINVAL; 164 } 165 166 return 0; 167 } 168 169 int tpm2_key_pub(void *context, size_t hdrlen, 170 unsigned char tag, 171 const void *value, size_t vlen) 172 { 173 struct tpm2_key_context *ctx = context; 174 175 ctx->pub = value; 176 ctx->pub_len = vlen; 177 178 return 0; 179 } 180 181 int tpm2_key_priv(void *context, size_t hdrlen, 182 unsigned char tag, 183 const void *value, size_t vlen) 184 { 185 struct tpm2_key_context *ctx = context; 186 187 ctx->priv = value; 188 ctx->priv_len = vlen; 189 190 return 0; 191 } 192 193 /** 194 * tpm2_buf_append_auth() - append TPMS_AUTH_COMMAND to the buffer. 195 * 196 * @buf: an allocated tpm_buf instance 197 * @session_handle: session handle 198 * @nonce: the session nonce, may be NULL if not used 199 * @nonce_len: the session nonce length, may be 0 if not used 200 * @attributes: the session attributes 201 * @hmac: the session HMAC or password, may be NULL if not used 202 * @hmac_len: the session HMAC or password length, maybe 0 if not used 203 */ 204 static void tpm2_buf_append_auth(struct tpm_buf *buf, u32 session_handle, 205 const u8 *nonce, u16 nonce_len, 206 u8 attributes, 207 const u8 *hmac, u16 hmac_len) 208 { 209 tpm_buf_append_u32(buf, 9 + nonce_len + hmac_len); 210 tpm_buf_append_u32(buf, session_handle); 211 tpm_buf_append_u16(buf, nonce_len); 212 213 if (nonce && nonce_len) 214 tpm_buf_append(buf, nonce, nonce_len); 215 216 tpm_buf_append_u8(buf, attributes); 217 tpm_buf_append_u16(buf, hmac_len); 218 219 if (hmac && hmac_len) 220 tpm_buf_append(buf, hmac, hmac_len); 221 } 222 223 /** 224 * tpm2_seal_trusted() - seal the payload of a trusted key 225 * 226 * @chip: TPM chip to use 227 * @payload: the key data in clear and encrypted form 228 * @options: authentication values and other options 229 * 230 * Return: < 0 on error and 0 on success. 231 */ 232 int tpm2_seal_trusted(struct tpm_chip *chip, 233 struct trusted_key_payload *payload, 234 struct trusted_key_options *options) 235 { 236 off_t offset = TPM_HEADER_SIZE; 237 struct tpm_buf buf, sized; 238 int blob_len = 0; 239 int hash; 240 u32 flags; 241 int rc; 242 243 hash = tpm2_find_hash_alg(options->hash); 244 if (hash < 0) 245 return hash; 246 247 if (!options->keyhandle) 248 return -EINVAL; 249 250 rc = tpm_try_get_ops(chip); 251 if (rc) 252 return rc; 253 254 rc = tpm2_start_auth_session(chip); 255 if (rc) 256 goto out_put; 257 258 rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE); 259 if (rc) { 260 tpm2_end_auth_session(chip); 261 goto out_put; 262 } 263 264 rc = tpm_buf_init_sized(&sized); 265 if (rc) { 266 tpm_buf_destroy(&buf); 267 tpm2_end_auth_session(chip); 268 goto out_put; 269 } 270 271 tpm_buf_append_name(chip, &buf, options->keyhandle, NULL); 272 tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_DECRYPT, 273 options->keyauth, TPM_DIGEST_SIZE); 274 275 /* sensitive */ 276 tpm_buf_append_u16(&sized, options->blobauth_len); 277 278 if (options->blobauth_len) 279 tpm_buf_append(&sized, options->blobauth, options->blobauth_len); 280 281 tpm_buf_append_u16(&sized, payload->key_len); 282 tpm_buf_append(&sized, payload->key, payload->key_len); 283 tpm_buf_append(&buf, sized.data, sized.length); 284 285 /* public */ 286 tpm_buf_reset_sized(&sized); 287 tpm_buf_append_u16(&sized, TPM_ALG_KEYEDHASH); 288 tpm_buf_append_u16(&sized, hash); 289 290 /* key properties */ 291 flags = 0; 292 flags |= options->policydigest_len ? 0 : TPM2_OA_USER_WITH_AUTH; 293 flags |= payload->migratable ? 0 : (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT); 294 tpm_buf_append_u32(&sized, flags); 295 296 /* policy */ 297 tpm_buf_append_u16(&sized, options->policydigest_len); 298 if (options->policydigest_len) 299 tpm_buf_append(&sized, options->policydigest, options->policydigest_len); 300 301 /* public parameters */ 302 tpm_buf_append_u16(&sized, TPM_ALG_NULL); 303 tpm_buf_append_u16(&sized, 0); 304 305 tpm_buf_append(&buf, sized.data, sized.length); 306 307 /* outside info */ 308 tpm_buf_append_u16(&buf, 0); 309 310 /* creation PCR */ 311 tpm_buf_append_u32(&buf, 0); 312 313 if (buf.flags & TPM_BUF_OVERFLOW) { 314 rc = -E2BIG; 315 tpm2_end_auth_session(chip); 316 goto out; 317 } 318 319 tpm_buf_fill_hmac_session(chip, &buf); 320 rc = tpm_transmit_cmd(chip, &buf, 4, "sealing data"); 321 rc = tpm_buf_check_hmac_response(chip, &buf, rc); 322 if (rc) 323 goto out; 324 325 blob_len = tpm_buf_read_u32(&buf, &offset); 326 if (blob_len > MAX_BLOB_SIZE || buf.flags & TPM_BUF_BOUNDARY_ERROR) { 327 rc = -E2BIG; 328 goto out; 329 } 330 if (buf.length - offset < blob_len) { 331 rc = -EFAULT; 332 goto out; 333 } 334 335 blob_len = tpm2_key_encode(payload, options, &buf.data[offset], blob_len); 336 337 out: 338 tpm_buf_destroy(&sized); 339 tpm_buf_destroy(&buf); 340 341 if (rc > 0) { 342 if (tpm2_rc_value(rc) == TPM2_RC_HASH) 343 rc = -EINVAL; 344 else 345 rc = -EPERM; 346 } 347 if (blob_len < 0) 348 rc = blob_len; 349 else 350 payload->blob_len = blob_len; 351 352 out_put: 353 tpm_put_ops(chip); 354 return rc; 355 } 356 357 /** 358 * tpm2_load_cmd() - execute a TPM2_Load command 359 * 360 * @chip: TPM chip to use 361 * @payload: the key data in clear and encrypted form 362 * @options: authentication values and other options 363 * @blob_handle: returned blob handle 364 * 365 * Return: 0 on success. 366 * -E2BIG on wrong payload size. 367 * -EPERM on tpm error status. 368 * < 0 error from tpm_send. 369 */ 370 static int tpm2_load_cmd(struct tpm_chip *chip, 371 struct trusted_key_payload *payload, 372 struct trusted_key_options *options, 373 u32 *blob_handle) 374 { 375 struct tpm_buf buf; 376 unsigned int private_len; 377 unsigned int public_len; 378 unsigned int blob_len; 379 u8 *blob, *pub; 380 int rc; 381 u32 attrs; 382 383 rc = tpm2_key_decode(payload, options, &blob); 384 if (rc) { 385 /* old form */ 386 blob = payload->blob; 387 payload->old_format = 1; 388 } 389 390 /* new format carries keyhandle but old format doesn't */ 391 if (!options->keyhandle) 392 return -EINVAL; 393 394 /* must be big enough for at least the two be16 size counts */ 395 if (payload->blob_len < 4) 396 return -EINVAL; 397 398 private_len = get_unaligned_be16(blob); 399 400 /* must be big enough for following public_len */ 401 if (private_len + 2 + 2 > (payload->blob_len)) 402 return -E2BIG; 403 404 public_len = get_unaligned_be16(blob + 2 + private_len); 405 if (private_len + 2 + public_len + 2 > payload->blob_len) 406 return -E2BIG; 407 408 pub = blob + 2 + private_len + 2; 409 /* key attributes are always at offset 4 */ 410 attrs = get_unaligned_be32(pub + 4); 411 412 if ((attrs & (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT)) == 413 (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT)) 414 payload->migratable = 0; 415 else 416 payload->migratable = 1; 417 418 blob_len = private_len + public_len + 4; 419 if (blob_len > payload->blob_len) 420 return -E2BIG; 421 422 rc = tpm2_start_auth_session(chip); 423 if (rc) 424 return rc; 425 426 rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD); 427 if (rc) { 428 tpm2_end_auth_session(chip); 429 return rc; 430 } 431 432 tpm_buf_append_name(chip, &buf, options->keyhandle, NULL); 433 tpm_buf_append_hmac_session(chip, &buf, 0, options->keyauth, 434 TPM_DIGEST_SIZE); 435 436 tpm_buf_append(&buf, blob, blob_len); 437 438 if (buf.flags & TPM_BUF_OVERFLOW) { 439 rc = -E2BIG; 440 tpm2_end_auth_session(chip); 441 goto out; 442 } 443 444 tpm_buf_fill_hmac_session(chip, &buf); 445 rc = tpm_transmit_cmd(chip, &buf, 4, "loading blob"); 446 rc = tpm_buf_check_hmac_response(chip, &buf, rc); 447 if (!rc) 448 *blob_handle = be32_to_cpup( 449 (__be32 *) &buf.data[TPM_HEADER_SIZE]); 450 451 out: 452 if (blob != payload->blob) 453 kfree(blob); 454 tpm_buf_destroy(&buf); 455 456 if (rc > 0) 457 rc = -EPERM; 458 459 return rc; 460 } 461 462 /** 463 * tpm2_unseal_cmd() - execute a TPM2_Unload command 464 * 465 * @chip: TPM chip to use 466 * @payload: the key data in clear and encrypted form 467 * @options: authentication values and other options 468 * @blob_handle: blob handle 469 * 470 * Return: 0 on success 471 * -EPERM on tpm error status 472 * < 0 error from tpm_send 473 */ 474 static int tpm2_unseal_cmd(struct tpm_chip *chip, 475 struct trusted_key_payload *payload, 476 struct trusted_key_options *options, 477 u32 blob_handle) 478 { 479 struct tpm_buf buf; 480 u16 data_len; 481 u8 *data; 482 int rc; 483 484 rc = tpm2_start_auth_session(chip); 485 if (rc) 486 return rc; 487 488 rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL); 489 if (rc) { 490 tpm2_end_auth_session(chip); 491 return rc; 492 } 493 494 tpm_buf_append_name(chip, &buf, blob_handle, NULL); 495 496 if (!options->policyhandle) { 497 tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT, 498 options->blobauth, 499 options->blobauth_len); 500 } else { 501 /* 502 * FIXME: The policy session was generated outside the 503 * kernel so we don't known the nonce and thus can't 504 * calculate a HMAC on it. Therefore, the user can 505 * only really use TPM2_PolicyPassword and we must 506 * send down the plain text password, which could be 507 * intercepted. We can still encrypt the returned 508 * key, but that's small comfort since the interposer 509 * could repeat our actions with the exfiltrated 510 * password. 511 */ 512 tpm2_buf_append_auth(&buf, options->policyhandle, 513 NULL /* nonce */, 0, 0, 514 options->blobauth, options->blobauth_len); 515 tpm_buf_append_hmac_session_opt(chip, &buf, TPM2_SA_ENCRYPT, 516 NULL, 0); 517 } 518 519 tpm_buf_fill_hmac_session(chip, &buf); 520 rc = tpm_transmit_cmd(chip, &buf, 6, "unsealing"); 521 rc = tpm_buf_check_hmac_response(chip, &buf, rc); 522 if (rc > 0) 523 rc = -EPERM; 524 525 if (!rc) { 526 data_len = be16_to_cpup( 527 (__be16 *) &buf.data[TPM_HEADER_SIZE + 4]); 528 if (data_len < MIN_KEY_SIZE || data_len > MAX_KEY_SIZE) { 529 rc = -EFAULT; 530 goto out; 531 } 532 533 if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + 6 + data_len) { 534 rc = -EFAULT; 535 goto out; 536 } 537 data = &buf.data[TPM_HEADER_SIZE + 6]; 538 539 if (payload->old_format) { 540 /* migratable flag is at the end of the key */ 541 memcpy(payload->key, data, data_len - 1); 542 payload->key_len = data_len - 1; 543 payload->migratable = data[data_len - 1]; 544 } else { 545 /* 546 * migratable flag already collected from key 547 * attributes 548 */ 549 memcpy(payload->key, data, data_len); 550 payload->key_len = data_len; 551 } 552 } 553 554 out: 555 tpm_buf_destroy(&buf); 556 return rc; 557 } 558 559 /** 560 * tpm2_unseal_trusted() - unseal the payload of a trusted key 561 * 562 * @chip: TPM chip to use 563 * @payload: the key data in clear and encrypted form 564 * @options: authentication values and other options 565 * 566 * Return: Same as with tpm_send. 567 */ 568 int tpm2_unseal_trusted(struct tpm_chip *chip, 569 struct trusted_key_payload *payload, 570 struct trusted_key_options *options) 571 { 572 u32 blob_handle; 573 int rc; 574 575 rc = tpm_try_get_ops(chip); 576 if (rc) 577 return rc; 578 579 rc = tpm2_load_cmd(chip, payload, options, &blob_handle); 580 if (rc) 581 goto out; 582 583 rc = tpm2_unseal_cmd(chip, payload, options, blob_handle); 584 tpm2_flush_context(chip, blob_handle); 585 586 out: 587 tpm_put_ops(chip); 588 589 return rc; 590 } 591