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 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
tpm2_key_encode(struct trusted_key_payload * payload,struct trusted_key_options * options,u8 * src,u32 len)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 int ret;
42
43 priv_len = get_unaligned_be16(src) + 2;
44 priv = src;
45
46 src += priv_len;
47
48 pub_len = get_unaligned_be16(src) + 2;
49 pub = src;
50
51 if (!scratch)
52 return -ENOMEM;
53
54 work = asn1_encode_oid(work, end_work, tpm2key_oid,
55 asn1_oid_len(tpm2key_oid));
56
57 if (options->blobauth_len == 0) {
58 unsigned char bool[3], *w = bool;
59 /* tag 0 is emptyAuth */
60 w = asn1_encode_boolean(w, w + sizeof(bool), true);
61 if (WARN(IS_ERR(w), "BUG: Boolean failed to encode")) {
62 ret = PTR_ERR(w);
63 goto err;
64 }
65 work = asn1_encode_tag(work, end_work, 0, bool, w - bool);
66 }
67
68 /*
69 * Assume both octet strings will encode to a 2 byte definite length
70 *
71 * Note: For a well behaved TPM, this warning should never
72 * trigger, so if it does there's something nefarious going on
73 */
74 if (WARN(work - scratch + pub_len + priv_len + 14 > SCRATCH_SIZE,
75 "BUG: scratch buffer is too small")) {
76 ret = -EINVAL;
77 goto err;
78 }
79
80 work = asn1_encode_integer(work, end_work, options->keyhandle);
81 work = asn1_encode_octet_string(work, end_work, pub, pub_len);
82 work = asn1_encode_octet_string(work, end_work, priv, priv_len);
83
84 work1 = payload->blob;
85 work1 = asn1_encode_sequence(work1, work1 + sizeof(payload->blob),
86 scratch, work - scratch);
87 if (IS_ERR(work1)) {
88 ret = PTR_ERR(work1);
89 pr_err("BUG: ASN.1 encoder failed with %d\n", ret);
90 goto err;
91 }
92
93 kfree(scratch);
94 return work1 - payload->blob;
95
96 err:
97 kfree(scratch);
98 return ret;
99 }
100
101 struct tpm2_key_context {
102 u32 parent;
103 const u8 *pub;
104 u32 pub_len;
105 const u8 *priv;
106 u32 priv_len;
107 };
108
tpm2_key_decode(struct trusted_key_payload * payload,struct trusted_key_options * options,u8 ** buf)109 static int tpm2_key_decode(struct trusted_key_payload *payload,
110 struct trusted_key_options *options,
111 u8 **buf)
112 {
113 int ret;
114 struct tpm2_key_context ctx;
115 u8 *blob;
116
117 memset(&ctx, 0, sizeof(ctx));
118
119 ret = asn1_ber_decoder(&tpm2key_decoder, &ctx, payload->blob,
120 payload->blob_len);
121 if (ret < 0)
122 return ret;
123
124 if (ctx.priv_len + ctx.pub_len > MAX_BLOB_SIZE)
125 return -EINVAL;
126
127 blob = kmalloc(ctx.priv_len + ctx.pub_len + 4, GFP_KERNEL);
128 if (!blob)
129 return -ENOMEM;
130
131 *buf = blob;
132 options->keyhandle = ctx.parent;
133
134 memcpy(blob, ctx.priv, ctx.priv_len);
135 blob += ctx.priv_len;
136
137 memcpy(blob, ctx.pub, ctx.pub_len);
138
139 return 0;
140 }
141
tpm2_key_parent(void * context,size_t hdrlen,unsigned char tag,const void * value,size_t vlen)142 int tpm2_key_parent(void *context, size_t hdrlen,
143 unsigned char tag,
144 const void *value, size_t vlen)
145 {
146 struct tpm2_key_context *ctx = context;
147 const u8 *v = value;
148 int i;
149
150 ctx->parent = 0;
151 for (i = 0; i < vlen; i++) {
152 ctx->parent <<= 8;
153 ctx->parent |= v[i];
154 }
155
156 return 0;
157 }
158
tpm2_key_type(void * context,size_t hdrlen,unsigned char tag,const void * value,size_t vlen)159 int tpm2_key_type(void *context, size_t hdrlen,
160 unsigned char tag,
161 const void *value, size_t vlen)
162 {
163 enum OID oid = look_up_OID(value, vlen);
164
165 if (oid != OID_TPMSealedData) {
166 char buffer[50];
167
168 sprint_oid(value, vlen, buffer, sizeof(buffer));
169 pr_debug("OID is \"%s\" which is not TPMSealedData\n",
170 buffer);
171 return -EINVAL;
172 }
173
174 return 0;
175 }
176
tpm2_key_pub(void * context,size_t hdrlen,unsigned char tag,const void * value,size_t vlen)177 int tpm2_key_pub(void *context, size_t hdrlen,
178 unsigned char tag,
179 const void *value, size_t vlen)
180 {
181 struct tpm2_key_context *ctx = context;
182
183 ctx->pub = value;
184 ctx->pub_len = vlen;
185
186 return 0;
187 }
188
tpm2_key_priv(void * context,size_t hdrlen,unsigned char tag,const void * value,size_t vlen)189 int tpm2_key_priv(void *context, size_t hdrlen,
190 unsigned char tag,
191 const void *value, size_t vlen)
192 {
193 struct tpm2_key_context *ctx = context;
194
195 ctx->priv = value;
196 ctx->priv_len = vlen;
197
198 return 0;
199 }
200
201 /**
202 * tpm2_buf_append_auth() - append TPMS_AUTH_COMMAND to the buffer.
203 *
204 * @buf: an allocated tpm_buf instance
205 * @session_handle: session handle
206 * @nonce: the session nonce, may be NULL if not used
207 * @nonce_len: the session nonce length, may be 0 if not used
208 * @attributes: the session attributes
209 * @hmac: the session HMAC or password, may be NULL if not used
210 * @hmac_len: the session HMAC or password length, maybe 0 if not used
211 */
tpm2_buf_append_auth(struct tpm_buf * buf,u32 session_handle,const u8 * nonce,u16 nonce_len,u8 attributes,const u8 * hmac,u16 hmac_len)212 static void tpm2_buf_append_auth(struct tpm_buf *buf, u32 session_handle,
213 const u8 *nonce, u16 nonce_len,
214 u8 attributes,
215 const u8 *hmac, u16 hmac_len)
216 {
217 tpm_buf_append_u32(buf, 9 + nonce_len + hmac_len);
218 tpm_buf_append_u32(buf, session_handle);
219 tpm_buf_append_u16(buf, nonce_len);
220
221 if (nonce && nonce_len)
222 tpm_buf_append(buf, nonce, nonce_len);
223
224 tpm_buf_append_u8(buf, attributes);
225 tpm_buf_append_u16(buf, hmac_len);
226
227 if (hmac && hmac_len)
228 tpm_buf_append(buf, hmac, hmac_len);
229 }
230
231 /**
232 * tpm2_seal_trusted() - seal the payload of a trusted key
233 *
234 * @chip: TPM chip to use
235 * @payload: the key data in clear and encrypted form
236 * @options: authentication values and other options
237 *
238 * Return: < 0 on error and 0 on success.
239 */
tpm2_seal_trusted(struct tpm_chip * chip,struct trusted_key_payload * payload,struct trusted_key_options * options)240 int tpm2_seal_trusted(struct tpm_chip *chip,
241 struct trusted_key_payload *payload,
242 struct trusted_key_options *options)
243 {
244 off_t offset = TPM_HEADER_SIZE;
245 struct tpm_buf buf, sized;
246 int blob_len = 0;
247 u32 hash;
248 u32 flags;
249 int i;
250 int rc;
251
252 for (i = 0; i < ARRAY_SIZE(tpm2_hash_map); i++) {
253 if (options->hash == tpm2_hash_map[i].crypto_id) {
254 hash = tpm2_hash_map[i].tpm_id;
255 break;
256 }
257 }
258
259 if (i == ARRAY_SIZE(tpm2_hash_map))
260 return -EINVAL;
261
262 if (!options->keyhandle)
263 return -EINVAL;
264
265 rc = tpm_try_get_ops(chip);
266 if (rc)
267 return rc;
268
269 rc = tpm2_start_auth_session(chip);
270 if (rc)
271 goto out_put;
272
273 rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
274 if (rc) {
275 tpm2_end_auth_session(chip);
276 goto out_put;
277 }
278
279 rc = tpm_buf_init_sized(&sized);
280 if (rc) {
281 tpm_buf_destroy(&buf);
282 tpm2_end_auth_session(chip);
283 goto out_put;
284 }
285
286 tpm_buf_append_name(chip, &buf, options->keyhandle, NULL);
287 tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_DECRYPT,
288 options->keyauth, TPM_DIGEST_SIZE);
289
290 /* sensitive */
291 tpm_buf_append_u16(&sized, options->blobauth_len);
292
293 if (options->blobauth_len)
294 tpm_buf_append(&sized, options->blobauth, options->blobauth_len);
295
296 tpm_buf_append_u16(&sized, payload->key_len);
297 tpm_buf_append(&sized, payload->key, payload->key_len);
298 tpm_buf_append(&buf, sized.data, sized.length);
299
300 /* public */
301 tpm_buf_reset_sized(&sized);
302 tpm_buf_append_u16(&sized, TPM_ALG_KEYEDHASH);
303 tpm_buf_append_u16(&sized, hash);
304
305 /* key properties */
306 flags = 0;
307 flags |= options->policydigest_len ? 0 : TPM2_OA_USER_WITH_AUTH;
308 flags |= payload->migratable ? 0 : (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT);
309 tpm_buf_append_u32(&sized, flags);
310
311 /* policy */
312 tpm_buf_append_u16(&sized, options->policydigest_len);
313 if (options->policydigest_len)
314 tpm_buf_append(&sized, options->policydigest, options->policydigest_len);
315
316 /* public parameters */
317 tpm_buf_append_u16(&sized, TPM_ALG_NULL);
318 tpm_buf_append_u16(&sized, 0);
319
320 tpm_buf_append(&buf, sized.data, sized.length);
321
322 /* outside info */
323 tpm_buf_append_u16(&buf, 0);
324
325 /* creation PCR */
326 tpm_buf_append_u32(&buf, 0);
327
328 if (buf.flags & TPM_BUF_OVERFLOW) {
329 rc = -E2BIG;
330 tpm2_end_auth_session(chip);
331 goto out;
332 }
333
334 tpm_buf_fill_hmac_session(chip, &buf);
335 rc = tpm_transmit_cmd(chip, &buf, 4, "sealing data");
336 rc = tpm_buf_check_hmac_response(chip, &buf, rc);
337 if (rc)
338 goto out;
339
340 blob_len = tpm_buf_read_u32(&buf, &offset);
341 if (blob_len > MAX_BLOB_SIZE || buf.flags & TPM_BUF_BOUNDARY_ERROR) {
342 rc = -E2BIG;
343 goto out;
344 }
345 if (buf.length - offset < blob_len) {
346 rc = -EFAULT;
347 goto out;
348 }
349
350 blob_len = tpm2_key_encode(payload, options, &buf.data[offset], blob_len);
351
352 out:
353 tpm_buf_destroy(&sized);
354 tpm_buf_destroy(&buf);
355
356 if (rc > 0) {
357 if (tpm2_rc_value(rc) == TPM2_RC_HASH)
358 rc = -EINVAL;
359 else
360 rc = -EPERM;
361 }
362 if (blob_len < 0)
363 rc = blob_len;
364 else
365 payload->blob_len = blob_len;
366
367 out_put:
368 tpm_put_ops(chip);
369 return rc;
370 }
371
372 /**
373 * tpm2_load_cmd() - execute a TPM2_Load command
374 *
375 * @chip: TPM chip to use
376 * @payload: the key data in clear and encrypted form
377 * @options: authentication values and other options
378 * @blob_handle: returned blob handle
379 *
380 * Return: 0 on success.
381 * -E2BIG on wrong payload size.
382 * -EPERM on tpm error status.
383 * < 0 error from tpm_send.
384 */
tpm2_load_cmd(struct tpm_chip * chip,struct trusted_key_payload * payload,struct trusted_key_options * options,u32 * blob_handle)385 static int tpm2_load_cmd(struct tpm_chip *chip,
386 struct trusted_key_payload *payload,
387 struct trusted_key_options *options,
388 u32 *blob_handle)
389 {
390 struct tpm_buf buf;
391 unsigned int private_len;
392 unsigned int public_len;
393 unsigned int blob_len;
394 u8 *blob, *pub;
395 int rc;
396 u32 attrs;
397
398 rc = tpm2_key_decode(payload, options, &blob);
399 if (rc) {
400 /* old form */
401 blob = payload->blob;
402 payload->old_format = 1;
403 }
404
405 /* new format carries keyhandle but old format doesn't */
406 if (!options->keyhandle)
407 return -EINVAL;
408
409 /* must be big enough for at least the two be16 size counts */
410 if (payload->blob_len < 4)
411 return -EINVAL;
412
413 private_len = get_unaligned_be16(blob);
414
415 /* must be big enough for following public_len */
416 if (private_len + 2 + 2 > (payload->blob_len))
417 return -E2BIG;
418
419 public_len = get_unaligned_be16(blob + 2 + private_len);
420 if (private_len + 2 + public_len + 2 > payload->blob_len)
421 return -E2BIG;
422
423 pub = blob + 2 + private_len + 2;
424 /* key attributes are always at offset 4 */
425 attrs = get_unaligned_be32(pub + 4);
426
427 if ((attrs & (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT)) ==
428 (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT))
429 payload->migratable = 0;
430 else
431 payload->migratable = 1;
432
433 blob_len = private_len + public_len + 4;
434 if (blob_len > payload->blob_len)
435 return -E2BIG;
436
437 rc = tpm2_start_auth_session(chip);
438 if (rc)
439 return rc;
440
441 rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
442 if (rc) {
443 tpm2_end_auth_session(chip);
444 return rc;
445 }
446
447 tpm_buf_append_name(chip, &buf, options->keyhandle, NULL);
448 tpm_buf_append_hmac_session(chip, &buf, 0, options->keyauth,
449 TPM_DIGEST_SIZE);
450
451 tpm_buf_append(&buf, blob, blob_len);
452
453 if (buf.flags & TPM_BUF_OVERFLOW) {
454 rc = -E2BIG;
455 tpm2_end_auth_session(chip);
456 goto out;
457 }
458
459 tpm_buf_fill_hmac_session(chip, &buf);
460 rc = tpm_transmit_cmd(chip, &buf, 4, "loading blob");
461 rc = tpm_buf_check_hmac_response(chip, &buf, rc);
462 if (!rc)
463 *blob_handle = be32_to_cpup(
464 (__be32 *) &buf.data[TPM_HEADER_SIZE]);
465
466 out:
467 if (blob != payload->blob)
468 kfree(blob);
469 tpm_buf_destroy(&buf);
470
471 if (rc > 0)
472 rc = -EPERM;
473
474 return rc;
475 }
476
477 /**
478 * tpm2_unseal_cmd() - execute a TPM2_Unload command
479 *
480 * @chip: TPM chip to use
481 * @payload: the key data in clear and encrypted form
482 * @options: authentication values and other options
483 * @blob_handle: blob handle
484 *
485 * Return: 0 on success
486 * -EPERM on tpm error status
487 * < 0 error from tpm_send
488 */
tpm2_unseal_cmd(struct tpm_chip * chip,struct trusted_key_payload * payload,struct trusted_key_options * options,u32 blob_handle)489 static int tpm2_unseal_cmd(struct tpm_chip *chip,
490 struct trusted_key_payload *payload,
491 struct trusted_key_options *options,
492 u32 blob_handle)
493 {
494 struct tpm_buf buf;
495 u16 data_len;
496 u8 *data;
497 int rc;
498
499 rc = tpm2_start_auth_session(chip);
500 if (rc)
501 return rc;
502
503 rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
504 if (rc) {
505 tpm2_end_auth_session(chip);
506 return rc;
507 }
508
509 tpm_buf_append_name(chip, &buf, blob_handle, NULL);
510
511 if (!options->policyhandle) {
512 tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT,
513 options->blobauth,
514 options->blobauth_len);
515 } else {
516 /*
517 * FIXME: The policy session was generated outside the
518 * kernel so we don't known the nonce and thus can't
519 * calculate a HMAC on it. Therefore, the user can
520 * only really use TPM2_PolicyPassword and we must
521 * send down the plain text password, which could be
522 * intercepted. We can still encrypt the returned
523 * key, but that's small comfort since the interposer
524 * could repeat our actions with the exfiltrated
525 * password.
526 */
527 tpm2_buf_append_auth(&buf, options->policyhandle,
528 NULL /* nonce */, 0, 0,
529 options->blobauth, options->blobauth_len);
530 tpm_buf_append_hmac_session_opt(chip, &buf, TPM2_SA_ENCRYPT,
531 NULL, 0);
532 }
533
534 tpm_buf_fill_hmac_session(chip, &buf);
535 rc = tpm_transmit_cmd(chip, &buf, 6, "unsealing");
536 rc = tpm_buf_check_hmac_response(chip, &buf, rc);
537 if (rc > 0)
538 rc = -EPERM;
539
540 if (!rc) {
541 data_len = be16_to_cpup(
542 (__be16 *) &buf.data[TPM_HEADER_SIZE + 4]);
543 if (data_len < MIN_KEY_SIZE || data_len > MAX_KEY_SIZE) {
544 rc = -EFAULT;
545 goto out;
546 }
547
548 if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + 6 + data_len) {
549 rc = -EFAULT;
550 goto out;
551 }
552 data = &buf.data[TPM_HEADER_SIZE + 6];
553
554 if (payload->old_format) {
555 /* migratable flag is at the end of the key */
556 memcpy(payload->key, data, data_len - 1);
557 payload->key_len = data_len - 1;
558 payload->migratable = data[data_len - 1];
559 } else {
560 /*
561 * migratable flag already collected from key
562 * attributes
563 */
564 memcpy(payload->key, data, data_len);
565 payload->key_len = data_len;
566 }
567 }
568
569 out:
570 tpm_buf_destroy(&buf);
571 return rc;
572 }
573
574 /**
575 * tpm2_unseal_trusted() - unseal the payload of a trusted key
576 *
577 * @chip: TPM chip to use
578 * @payload: the key data in clear and encrypted form
579 * @options: authentication values and other options
580 *
581 * Return: Same as with tpm_send.
582 */
tpm2_unseal_trusted(struct tpm_chip * chip,struct trusted_key_payload * payload,struct trusted_key_options * options)583 int tpm2_unseal_trusted(struct tpm_chip *chip,
584 struct trusted_key_payload *payload,
585 struct trusted_key_options *options)
586 {
587 u32 blob_handle;
588 int rc;
589
590 rc = tpm_try_get_ops(chip);
591 if (rc)
592 return rc;
593
594 rc = tpm2_load_cmd(chip, payload, options, &blob_handle);
595 if (rc)
596 goto out;
597
598 rc = tpm2_unseal_cmd(chip, payload, options, blob_handle);
599 tpm2_flush_context(chip, blob_handle);
600
601 out:
602 tpm_put_ops(chip);
603
604 return rc;
605 }
606