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
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 int blob_len = 0;
245 struct tpm_buf buf;
246 u32 hash;
247 u32 flags;
248 int i;
249 int rc;
250
251 for (i = 0; i < ARRAY_SIZE(tpm2_hash_map); i++) {
252 if (options->hash == tpm2_hash_map[i].crypto_id) {
253 hash = tpm2_hash_map[i].tpm_id;
254 break;
255 }
256 }
257
258 if (i == ARRAY_SIZE(tpm2_hash_map))
259 return -EINVAL;
260
261 if (!options->keyhandle)
262 return -EINVAL;
263
264 rc = tpm_try_get_ops(chip);
265 if (rc)
266 return rc;
267
268 rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
269 if (rc) {
270 tpm_put_ops(chip);
271 return rc;
272 }
273
274 tpm_buf_append_u32(&buf, options->keyhandle);
275 tpm2_buf_append_auth(&buf, TPM2_RS_PW,
276 NULL /* nonce */, 0,
277 0 /* session_attributes */,
278 options->keyauth /* hmac */,
279 TPM_DIGEST_SIZE);
280
281 /* sensitive */
282 tpm_buf_append_u16(&buf, 4 + options->blobauth_len + payload->key_len);
283
284 tpm_buf_append_u16(&buf, options->blobauth_len);
285 if (options->blobauth_len)
286 tpm_buf_append(&buf, options->blobauth, options->blobauth_len);
287
288 tpm_buf_append_u16(&buf, payload->key_len);
289 tpm_buf_append(&buf, payload->key, payload->key_len);
290
291 /* public */
292 tpm_buf_append_u16(&buf, 14 + options->policydigest_len);
293 tpm_buf_append_u16(&buf, TPM_ALG_KEYEDHASH);
294 tpm_buf_append_u16(&buf, hash);
295
296 /* key properties */
297 flags = 0;
298 flags |= options->policydigest_len ? 0 : TPM2_OA_USER_WITH_AUTH;
299 flags |= payload->migratable ? 0 : (TPM2_OA_FIXED_TPM |
300 TPM2_OA_FIXED_PARENT);
301 tpm_buf_append_u32(&buf, flags);
302
303 /* policy */
304 tpm_buf_append_u16(&buf, options->policydigest_len);
305 if (options->policydigest_len)
306 tpm_buf_append(&buf, options->policydigest,
307 options->policydigest_len);
308
309 /* public parameters */
310 tpm_buf_append_u16(&buf, TPM_ALG_NULL);
311 tpm_buf_append_u16(&buf, 0);
312
313 /* outside info */
314 tpm_buf_append_u16(&buf, 0);
315
316 /* creation PCR */
317 tpm_buf_append_u32(&buf, 0);
318
319 if (buf.flags & TPM_BUF_OVERFLOW) {
320 rc = -E2BIG;
321 goto out;
322 }
323
324 rc = tpm_transmit_cmd(chip, &buf, 4, "sealing data");
325 if (rc)
326 goto out;
327
328 blob_len = be32_to_cpup((__be32 *) &buf.data[TPM_HEADER_SIZE]);
329 if (blob_len > MAX_BLOB_SIZE) {
330 rc = -E2BIG;
331 goto out;
332 }
333 if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + 4 + blob_len) {
334 rc = -EFAULT;
335 goto out;
336 }
337
338 blob_len = tpm2_key_encode(payload, options,
339 &buf.data[TPM_HEADER_SIZE + 4],
340 blob_len);
341
342 out:
343 tpm_buf_destroy(&buf);
344
345 if (rc > 0) {
346 if (tpm2_rc_value(rc) == TPM2_RC_HASH)
347 rc = -EINVAL;
348 else
349 rc = -EPERM;
350 }
351 if (blob_len < 0)
352 rc = blob_len;
353 else
354 payload->blob_len = blob_len;
355
356 tpm_put_ops(chip);
357 return rc;
358 }
359
360 /**
361 * tpm2_load_cmd() - execute a TPM2_Load command
362 *
363 * @chip: TPM chip to use
364 * @payload: the key data in clear and encrypted form
365 * @options: authentication values and other options
366 * @blob_handle: returned blob handle
367 *
368 * Return: 0 on success.
369 * -E2BIG on wrong payload size.
370 * -EPERM on tpm error status.
371 * < 0 error from tpm_send.
372 */
tpm2_load_cmd(struct tpm_chip * chip,struct trusted_key_payload * payload,struct trusted_key_options * options,u32 * blob_handle)373 static int tpm2_load_cmd(struct tpm_chip *chip,
374 struct trusted_key_payload *payload,
375 struct trusted_key_options *options,
376 u32 *blob_handle)
377 {
378 struct tpm_buf buf;
379 unsigned int private_len;
380 unsigned int public_len;
381 unsigned int blob_len;
382 u8 *blob, *pub;
383 int rc;
384 u32 attrs;
385
386 rc = tpm2_key_decode(payload, options, &blob);
387 if (rc) {
388 /* old form */
389 blob = payload->blob;
390 payload->old_format = 1;
391 }
392
393 /* new format carries keyhandle but old format doesn't */
394 if (!options->keyhandle)
395 return -EINVAL;
396
397 /* must be big enough for at least the two be16 size counts */
398 if (payload->blob_len < 4)
399 return -EINVAL;
400
401 private_len = get_unaligned_be16(blob);
402
403 /* must be big enough for following public_len */
404 if (private_len + 2 + 2 > (payload->blob_len))
405 return -E2BIG;
406
407 public_len = get_unaligned_be16(blob + 2 + private_len);
408 if (private_len + 2 + public_len + 2 > payload->blob_len)
409 return -E2BIG;
410
411 pub = blob + 2 + private_len + 2;
412 /* key attributes are always at offset 4 */
413 attrs = get_unaligned_be32(pub + 4);
414
415 if ((attrs & (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT)) ==
416 (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT))
417 payload->migratable = 0;
418 else
419 payload->migratable = 1;
420
421 blob_len = private_len + public_len + 4;
422 if (blob_len > payload->blob_len)
423 return -E2BIG;
424
425 rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
426 if (rc)
427 return rc;
428
429 tpm_buf_append_u32(&buf, options->keyhandle);
430 tpm2_buf_append_auth(&buf, TPM2_RS_PW,
431 NULL /* nonce */, 0,
432 0 /* session_attributes */,
433 options->keyauth /* hmac */,
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 goto out;
441 }
442
443 rc = tpm_transmit_cmd(chip, &buf, 4, "loading blob");
444 if (!rc)
445 *blob_handle = be32_to_cpup(
446 (__be32 *) &buf.data[TPM_HEADER_SIZE]);
447
448 out:
449 if (blob != payload->blob)
450 kfree(blob);
451 tpm_buf_destroy(&buf);
452
453 if (rc > 0)
454 rc = -EPERM;
455
456 return rc;
457 }
458
459 /**
460 * tpm2_unseal_cmd() - execute a TPM2_Unload command
461 *
462 * @chip: TPM chip to use
463 * @payload: the key data in clear and encrypted form
464 * @options: authentication values and other options
465 * @blob_handle: blob handle
466 *
467 * Return: 0 on success
468 * -EPERM on tpm error status
469 * < 0 error from tpm_send
470 */
tpm2_unseal_cmd(struct tpm_chip * chip,struct trusted_key_payload * payload,struct trusted_key_options * options,u32 blob_handle)471 static int tpm2_unseal_cmd(struct tpm_chip *chip,
472 struct trusted_key_payload *payload,
473 struct trusted_key_options *options,
474 u32 blob_handle)
475 {
476 struct tpm_buf buf;
477 u16 data_len;
478 u8 *data;
479 int rc;
480
481 rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
482 if (rc)
483 return rc;
484
485 tpm_buf_append_u32(&buf, blob_handle);
486 tpm2_buf_append_auth(&buf,
487 options->policyhandle ?
488 options->policyhandle : TPM2_RS_PW,
489 NULL /* nonce */, 0,
490 TPM2_SA_CONTINUE_SESSION,
491 options->blobauth /* hmac */,
492 options->blobauth_len);
493
494 rc = tpm_transmit_cmd(chip, &buf, 6, "unsealing");
495 if (rc > 0)
496 rc = -EPERM;
497
498 if (!rc) {
499 data_len = be16_to_cpup(
500 (__be16 *) &buf.data[TPM_HEADER_SIZE + 4]);
501 if (data_len < MIN_KEY_SIZE || data_len > MAX_KEY_SIZE) {
502 rc = -EFAULT;
503 goto out;
504 }
505
506 if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + 6 + data_len) {
507 rc = -EFAULT;
508 goto out;
509 }
510 data = &buf.data[TPM_HEADER_SIZE + 6];
511
512 if (payload->old_format) {
513 /* migratable flag is at the end of the key */
514 memcpy(payload->key, data, data_len - 1);
515 payload->key_len = data_len - 1;
516 payload->migratable = data[data_len - 1];
517 } else {
518 /*
519 * migratable flag already collected from key
520 * attributes
521 */
522 memcpy(payload->key, data, data_len);
523 payload->key_len = data_len;
524 }
525 }
526
527 out:
528 tpm_buf_destroy(&buf);
529 return rc;
530 }
531
532 /**
533 * tpm2_unseal_trusted() - unseal the payload of a trusted key
534 *
535 * @chip: TPM chip to use
536 * @payload: the key data in clear and encrypted form
537 * @options: authentication values and other options
538 *
539 * Return: Same as with tpm_send.
540 */
tpm2_unseal_trusted(struct tpm_chip * chip,struct trusted_key_payload * payload,struct trusted_key_options * options)541 int tpm2_unseal_trusted(struct tpm_chip *chip,
542 struct trusted_key_payload *payload,
543 struct trusted_key_options *options)
544 {
545 u32 blob_handle;
546 int rc;
547
548 rc = tpm_try_get_ops(chip);
549 if (rc)
550 return rc;
551
552 rc = tpm2_load_cmd(chip, payload, options, &blob_handle);
553 if (rc)
554 goto out;
555
556 rc = tpm2_unseal_cmd(chip, payload, options, blob_handle);
557 tpm2_flush_context(chip, blob_handle);
558
559 out:
560 tpm_put_ops(chip);
561
562 return rc;
563 }
564