summaryrefslogtreecommitdiffstats
path: root/crypto/asymmetric_keys/asym_tpm.c
blob: d16d893bd1959ca7d69eab2b011faa13c8e410c9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
// SPDX-License-Identifier: GPL-2.0
#define pr_fmt(fmt) "ASYM-TPM: "fmt
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/seq_file.h>
#include <linux/scatterlist.h>
#include <linux/tpm.h>
#include <linux/tpm_command.h>
#include <crypto/akcipher.h>
#include <crypto/hash.h>
#include <crypto/sha.h>
#include <asm/unaligned.h>
#include <keys/asymmetric-subtype.h>
#include <keys/trusted_tpm.h>
#include <crypto/asym_tpm_subtype.h>
#include <crypto/public_key.h>

#define TPM_ORD_FLUSHSPECIFIC	186
#define TPM_ORD_LOADKEY2	65
#define TPM_ORD_UNBIND		30
#define TPM_ORD_SIGN		60

#define TPM_RT_KEY                      0x00000001

/*
 * Load a TPM key from the blob provided by userspace
 */
static int tpm_loadkey2(struct tpm_buf *tb,
			uint32_t keyhandle, unsigned char *keyauth,
			const unsigned char *keyblob, int keybloblen,
			uint32_t *newhandle)
{
	unsigned char nonceodd[TPM_NONCE_SIZE];
	unsigned char enonce[TPM_NONCE_SIZE];
	unsigned char authdata[SHA1_DIGEST_SIZE];
	uint32_t authhandle = 0;
	unsigned char cont = 0;
	uint32_t ordinal;
	int ret;

	ordinal = htonl(TPM_ORD_LOADKEY2);

	/* session for loading the key */
	ret = oiap(tb, &authhandle, enonce);
	if (ret < 0) {
		pr_info("oiap failed (%d)\n", ret);
		return ret;
	}

	/* generate odd nonce */
	ret = tpm_get_random(NULL, nonceodd, TPM_NONCE_SIZE);
	if (ret < 0) {
		pr_info("tpm_get_random failed (%d)\n", ret);
		return ret;
	}

	/* calculate authorization HMAC value */
	ret = TSS_authhmac(authdata, keyauth, SHA1_DIGEST_SIZE, enonce,
			   nonceodd, cont, sizeof(uint32_t), &ordinal,
			   keybloblen, keyblob, 0, 0);
	if (ret < 0)
		return ret;

	/* build the request buffer */
	tpm_buf_reset(tb, TPM_TAG_RQU_AUTH1_COMMAND, TPM_ORD_LOADKEY2);
	tpm_buf_append_u32(tb, keyhandle);
	tpm_buf_append(tb, keyblob, keybloblen);
	tpm_buf_append_u32(tb, authhandle);
	tpm_buf_append(tb, nonceodd, TPM_NONCE_SIZE);
	tpm_buf_append_u8(tb, cont);
	tpm_buf_append(tb, authdata, SHA1_DIGEST_SIZE);

	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
	if (ret < 0) {
		pr_info("authhmac failed (%d)\n", ret);
		return ret;
	}

	ret = TSS_checkhmac1(tb->data, ordinal, nonceodd, keyauth,
			     SHA1_DIGEST_SIZE, 0, 0);
	if (ret < 0) {
		pr_info("TSS_checkhmac1 failed (%d)\n", ret);
		return ret;
	}

	*newhandle = LOAD32(tb->data, TPM_DATA_OFFSET);
	return 0;
}

/*
 * Execute the FlushSpecific TPM command
 */
static int tpm_flushspecific(struct tpm_buf *tb, uint32_t handle)
{
	tpm_buf_reset(tb, TPM_TAG_RQU_COMMAND, TPM_ORD_FLUSHSPECIFIC);
	tpm_buf_append_u32(tb, handle);
	tpm_buf_append_u32(tb, TPM_RT_KEY);

	return trusted_tpm_send(tb->data, MAX_BUF_SIZE);
}

/*
 * Decrypt a blob provided by userspace using a specific key handle.
 * The handle is a well known handle or previously loaded by e.g. LoadKey2
 */
static int tpm_unbind(struct tpm_buf *tb,
			uint32_t keyhandle, unsigned char *keyauth,
			const unsigned char *blob, uint32_t bloblen,
			void *out, uint32_t outlen)
{
	unsigned char nonceodd[TPM_NONCE_SIZE];
	unsigned char enonce[TPM_NONCE_SIZE];
	unsigned char authdata[SHA1_DIGEST_SIZE];
	uint32_t authhandle = 0;
	unsigned char cont = 0;
	uint32_t ordinal;
	uint32_t datalen;
	int ret;

	ordinal = htonl(TPM_ORD_UNBIND);
	datalen = htonl(bloblen);

	/* session for loading the key */
	ret = oiap(tb, &authhandle, enonce);
	if (ret < 0) {
		pr_info("oiap failed (%d)\n", ret);
		return ret;
	}

	/* generate odd nonce */
	ret = tpm_get_random(NULL, nonceodd, TPM_NONCE_SIZE);
	if (ret < 0) {
		pr_info("tpm_get_random failed (%d)\n", ret);
		return ret;
	}

	/* calculate authorization HMAC value */
	ret = TSS_authhmac(authdata, keyauth, SHA1_DIGEST_SIZE, enonce,
			   nonceodd, cont, sizeof(uint32_t), &ordinal,
			   sizeof(uint32_t), &datalen,
			   bloblen, blob, 0, 0);
	if (ret < 0)
		return ret;

	/* build the request buffer */
	tpm_buf_reset(tb, TPM_TAG_RQU_AUTH1_COMMAND, TPM_ORD_UNBIND);
	tpm_buf_append_u32(tb, keyhandle);
	tpm_buf_append_u32(tb, bloblen);
	tpm_buf_append(tb, blob, bloblen);
	tpm_buf_append_u32(tb, authhandle);
	tpm_buf_append(tb, nonceodd, TPM_NONCE_SIZE);
	tpm_buf_append_u8(tb, cont);
	tpm_buf_append(tb, authdata, SHA1_DIGEST_SIZE);

	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
	if (ret < 0) {
		pr_info("authhmac failed (%d)\n", ret);
		return ret;
	}

	datalen = LOAD32(tb->data, TPM_DATA_OFFSET);

	ret = TSS_checkhmac1(tb->data, ordinal, nonceodd,
			     keyauth, SHA1_DIGEST_SIZE,
			     sizeof(uint32_t), TPM_DATA_OFFSET,
			     datalen, TPM_DATA_OFFSET + sizeof(uint32_t),
			     0, 0);
	if (ret < 0) {
		pr_info("TSS_checkhmac1 failed (%d)\n", ret);
		return ret;
	}

	memcpy(out, tb->data + TPM_DATA_OFFSET + sizeof(uint32_t),
	       min(outlen, datalen));

	return datalen;
}

/*
 * Sign a blob provided by userspace (that has had the hash function applied)
 * using a specific key handle.  The handle is assumed to have been previously
 * loaded by e.g. LoadKey2.
 *
 * Note that the key signature scheme of the used key should be set to
 * TPM_SS_RSASSAPKCS1v15_DER.  This allows the hashed input to be of any size
 * up to key_length_in_bytes - 11 and not be limited to size 20 like the
 * TPM_SS_RSASSAPKCS1v15_SHA1 signature scheme.
 */
static int tpm_sign(struct tpm_buf *tb,
		    uint32_t keyhandle, unsigned char *keyauth,
		    const unsigned char *blob, uint32_t bloblen,
		    void *out, uint32_t outlen)
{
	unsigned char nonceodd[TPM_NONCE_SIZE];
	unsigned char enonce[TPM_NONCE_SIZE];
	unsigned char authdata[SHA1_DIGEST_SIZE];
	uint32_t authhandle = 0;
	unsigned char cont = 0;
	uint32_t ordinal;
	uint32_t datalen;
	int ret;

	ordinal = htonl(TPM_ORD_SIGN);
	datalen = htonl(bloblen);

	/* session for loading the key */
	ret = oiap(tb, &authhandle, enonce);
	if (ret < 0) {
		pr_info("oiap failed (%d)\n", ret);
		return ret;
	}

	/* generate odd nonce */
	ret = tpm_get_random(NULL, nonceodd, TPM_NONCE_SIZE);
	if (ret < 0) {
		pr_info("tpm_get_random failed (%d)\n", ret);
		return ret;
	}

	/* calculate authorization HMAC value */
	ret = TSS_authhmac(authdata, keyauth, SHA1_DIGEST_SIZE, enonce,
			   nonceodd, cont, sizeof(uint32_t), &ordinal,
			   sizeof(uint32_t), &datalen,
			   bloblen, blob, 0, 0);
	if (ret < 0)
		return ret;

	/* build the request buffer */
	tpm_buf_reset(tb, TPM_TAG_RQU_AUTH1_COMMAND, TPM_ORD_SIGN);
	tpm_buf_append_u32(tb, keyhandle);
	tpm_buf_append_u32(tb, bloblen);
	tpm_buf_append(tb, blob, bloblen);
	tpm_buf_append_u32(tb, authhandle);
	tpm_buf_append(tb, nonceodd, TPM_NONCE_SIZE);
	tpm_buf_append_u8(tb, cont);
	tpm_buf_append(tb, authdata, SHA1_DIGEST_SIZE);

	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
	if (ret < 0) {
		pr_info("authhmac failed (%d)\n", ret);
		return ret;
	}

	datalen = LOAD32(tb->data, TPM_DATA_OFFSET);

	ret = TSS_checkhmac1(tb->data, ordinal, nonceodd,
			     keyauth, SHA1_DIGEST_SIZE,
			     sizeof(uint32_t), TPM_DATA_OFFSET,
			     datalen, TPM_DATA_OFFSET + sizeof(uint32_t),
			     0, 0);
	if (ret < 0) {
		pr_info("TSS_checkhmac1 failed (%d)\n", ret);
		return ret;
	}

	memcpy(out, tb->data + TPM_DATA_OFFSET + sizeof(uint32_t),
	       min(datalen, outlen));

	return datalen;
}

/* Room to fit two u32 zeros for algo id and parameters length. */
#define SETKEY_PARAMS_SIZE (sizeof(u32) * 2)

/*
 * Maximum buffer size for the BER/DER encoded public key.  The public key
 * is of the form SEQUENCE { INTEGER n, INTEGER e } where n is a maximum 2048
 * bit key and e is usually 65537
 * The encoding overhead is:
 * - max 4 bytes for SEQUENCE
 *   - max 4 bytes for INTEGER n type/length
 *     - 257 bytes of n
 *   - max 2 bytes for INTEGER e type/length
 *     - 3 bytes of e
 * - 4+4 of zeros for set_pub_key parameters (SETKEY_PARAMS_SIZE)
 */
#define PUB_KEY_BUF_SIZE (4 + 4 + 257 + 2 + 3 + SETKEY_PARAMS_SIZE)

/*
 * Provide a part of a description of the key for /proc/keys.
 */
static void asym_tpm_describe(const struct key *asymmetric_key,
			      struct seq_file *m)
{
	struct tpm_key *tk = asymmetric_key->payload.data[asym_crypto];

	if (!tk)
		return;

	seq_printf(m, "TPM1.2/Blob");
}

static void asym_tpm_destroy(void *payload0, void *payload3)
{
	struct tpm_key *tk = payload0;

	if (!tk)
		return;

	kfree(tk->blob);
	tk->blob_len = 0;

	kfree(tk);
}

/* How many bytes will it take to encode the length */
static inline uint32_t definite_length(uint32_t len)
{
	if (len <= 127)
		return 1;
	if (len <= 255)
		return 2;
	return 3;
}

static inline uint8_t *encode_tag_length(uint8_t *buf, uint8_t tag,
					 uint32_t len)
{
	*buf++ = tag;

	if (len <= 127) {
		buf[0] = len;
		return buf + 1;
	}

	if (len <= 255) {
		buf[0] = 0x81;
		buf[1] = len;
		return buf + 2;
	}

	buf[0] = 0x82;
	put_unaligned_be16(len, buf + 1);
	return buf + 3;
}

static uint32_t derive_pub_key(const void *pub_key, uint32_t len, uint8_t *buf)
{
	uint8_t *cur = buf;
	uint32_t n_len = definite_length(len) + 1 + len + 1;
	uint32_t e_len = definite_length(3) + 1 + 3;
	uint8_t e[3] = { 0x01, 0x00, 0x01 };

	/* SEQUENCE */
	cur = encode_tag_length(cur, 0x30, n_len + e_len);
	/* INTEGER n */
	cur = encode_tag_length(cur, 0x02, len + 1);
	cur[0] = 0x00;
	memcpy(cur + 1, pub_key, len);
	cur += len + 1;
	cur = encode_tag_length(cur, 0x02, sizeof(e));
	memcpy(cur, e, sizeof(e));
	cur += sizeof(e);
	/* Zero parameters to satisfy set_pub_key ABI. */
	memset(cur, 0, SETKEY_PARAMS_SIZE);

	return cur - buf;
}

/*
 * Determine the crypto algorithm name.
 */
static int determine_akcipher(const char *encoding, const char *hash_algo,
			      char alg_name[CRYPTO_MAX_ALG_NAME])
{
	if (strcmp(encoding, "pkcs1") == 0) {
		if (!hash_algo) {
			strcpy(alg_name, "pkcs1pad(rsa)");
			return 0;
		}

		if (snprintf(alg_name, CRYPTO_MAX_ALG_NAME, "pkcs1pad(rsa,%s)",
			     hash_algo) >= CRYPTO_MAX_ALG_NAME)
			return -EINVAL;

		return 0;
	}

	if (strcmp(encoding, "raw") == 0) {
		strcpy(alg_name, "rsa");
		return 0;
	}

	return -ENOPKG;
}

/*
 * Query information about a key.
 */
static int tpm_key_query(const struct kernel_pkey_params *params,
			 struct kernel_pkey_query *info)
{
	struct tpm_key *tk = params->key->payload.data[asym_crypto];
	int ret;
	char alg_name[CRYPTO_MAX_ALG_NAME];
	struct crypto_akcipher *tfm;
	uint8_t der_pub_key[PUB_KEY_BUF_SIZE];
	uint32_t der_pub_key_len;
	int len;

	/* TPM only works on private keys, public keys still done in software */
	ret = determine_akcipher(params->encoding, params->hash_algo, alg_name);
	if (ret < 0)
		return ret;

	tfm = crypto_alloc_akcipher(alg_name, 0, 0);
	if (IS_ERR(tfm))
		return PTR_ERR(tfm);

	der_pub_key_len = derive_pub_key(tk->pub_key, tk->pub_key_len,
					 der_pub_key);

	ret = crypto_akcipher_set_pub_key(tfm, der_pub_key, der_pub_key_len);
	if (ret < 0)
		goto error_free_tfm;

	len = crypto_akcipher_maxsize(tfm);

	info->key_size = tk->key_len;
	info->max_data_size = tk->key_len / 8;
	info->max_sig_size = len;
	info->max_enc_size = len;
	info->max_dec_size = tk->key_len / 8;

	info->supported_ops = KEYCTL_SUPPORTS_ENCRYPT |
			      KEYCTL_SUPPORTS_DECRYPT |
			      KEYCTL_SUPPORTS_VERIFY |
			      KEYCTL_SUPPORTS_SIGN;

	ret = 0;
error_free_tfm:
	crypto_free_akcipher(tfm);
	pr_devel("<==%s() = %d\n", __func__, ret);
	return ret;
}

/*
 * Encryption operation is performed with the public key.  Hence it is done
 * in software
 */
static int tpm_key_encrypt(struct tpm_key *tk,
			   struct kernel_pkey_params *params,
			   const void *in, void *out)
{
	char alg_name[CRYPTO_MAX_ALG_NAME];
	struct crypto_akcipher *tfm;
	struct akcipher_request *req;
	struct crypto_wait cwait;
	struct scatterlist in_sg, out_sg;
	uint8_t der_pub_key[PUB_KEY_BUF_SIZE];
	uint32_t der_pub_key_len;
	int ret;

	pr_devel("==>%s()\n", __func__);

	ret = determine_akcipher(params->encoding, params->hash_algo, alg_name);
	if (ret < 0)
		return ret;

	tfm = crypto_alloc_akcipher(alg_name, 0, 0);
	if (IS_ERR(tfm))
		return PTR_ERR(tfm);

	der_pub_key_len = derive_pub_key(tk->pub_key, tk->pub_key_len,
					 der_pub_key);

	ret = crypto_akcipher_set_pub_key(tfm, der_pub_key, der_pub_key_len);
	if (ret < 0)
		goto error_free_tfm;

	req = akcipher_request_alloc(tfm, GFP_KERNEL);
	if (!req)
		goto error_free_tfm;

	sg_init_one(&in_sg, in, params->in_len);
	sg_init_one(&out_sg, out, params->out_len);
	akcipher_request_set_crypt(req, &in_sg, &out_sg, params->in_len,
				   params->out_len);
	crypto_init_wait(&cwait);
	akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
				      CRYPTO_TFM_REQ_MAY_SLEEP,
				      crypto_req_done, &cwait);

	ret = crypto_akcipher_encrypt(req);
	ret = crypto_wait_req(ret, &cwait);

	if (ret == 0)
		ret = req->dst_len;

	akcipher_request_free(req);
error_free_tfm:
	crypto_free_akcipher(tfm);
	pr_devel("<==%s() = %d\n", __func__, ret);
	return ret;
}

/*
 * Decryption operation is performed with the private key in the TPM.
 */
static int tpm_key_decrypt(struct tpm_key *tk,
			   struct kernel_pkey_params *params,
			   const void *in, void *out)
{
	struct tpm_buf tb;
	uint32_t keyhandle;
	uint8_t srkauth[SHA1_DIGEST_SIZE];
	uint8_t keyauth[SHA1_DIGEST_SIZE];
	int r;

	pr_devel("==>%s()\n", __func__);

	if (params->hash_algo)
		return -ENOPKG;

	if (strcmp(params->encoding, "pkcs1"))
		return -ENOPKG;

	r = tpm_buf_init(&tb, 0, 0);
	if (r)
		return r;

	/* TODO: Handle a non-all zero SRK authorization */
	memset(srkauth, 0, sizeof(srkauth));

	r = tpm_loadkey2(&tb, SRKHANDLE, srkauth,
				tk->blob, tk->blob_len, &keyhandle);
	if (r < 0) {
		pr_devel("loadkey2 failed (%d)\n", r);
		goto error;
	}

	/* TODO: Handle a non-all zero key authorization */
	memset(keyauth, 0, sizeof(keyauth));

	r = tpm_unbind(&tb, keyhandle, keyauth,
		       in, params->in_len, out, params->out_len);
	if (r < 0)
		pr_devel("tpm_unbind failed (%d)\n", r);

	if (tpm_flushspecific(&tb, keyhandle) < 0)
		pr_devel("flushspecific failed (%d)\n", r);

error:
	tpm_buf_destroy(&tb);
	pr_devel("<==%s() = %d\n", __func__, r);
	return r;
}

/*
 * Hash algorithm OIDs plus ASN.1 DER wrappings [RFC4880 sec 5.2.2].
 */
static const u8 digest_info_md5[] = {
	0x30, 0x20, 0x30, 0x0c, 0x06, 0x08,
	0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x05, /* OID */
	0x05, 0x00, 0x04, 0x10
};

static const u8 digest_info_sha1[] = {
	0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
	0x2b, 0x0e, 0x03, 0x02, 0x1a,
	0x05, 0x00, 0x04, 0x14
};

static const u8 digest_info_rmd160[] = {
	0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
	0x2b, 0x24, 0x03, 0x02, 0x01,
	0x05, 0x00, 0x04, 0x14
};

static const u8 digest_info_sha224[] = {
	0x30, 0x2d, 0x30, 0x0d, 0x06, 0x09,
	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04,
	0x05, 0x00, 0x04, 0x1c
};

static const u8 digest_info_sha256[] = {
	0x30, 0x31, 0x30, 0x0d, 0x06, 0x09,
	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01,
	0x05, 0x00, 0x04, 0x20
};

static const u8 digest_info_sha384[] = {
	0x30, 0x41, 0x30, 0x0d, 0x06, 0x09,
	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02,
	0x05, 0x00, 0x04, 0x30
};

static const u8 digest_info_sha512[] = {
	0x30, 0x51, 0x30, 0x0d, 0x06, 0x09,
	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03,
	0x05, 0x00, 0x04, 0x40
};

static const struct asn1_template {
	const char	*name;
	const u8	*data;
	size_t		size;
} asn1_templates[] = {
#define _(X) { #X, digest_info_##X, sizeof(digest_info_##X) }
	_(md5),
	_(sha1),
	_(rmd160),
	_(sha256),
	_(sha384),
	_(sha512),
	_(sha224),
	{ NULL }
#undef _
};

static const struct asn1_template *lookup_asn1(const char *name)
{
	const struct asn1_template *p;

	for (p = asn1_templates; p->name; p++)
		if (strcmp(name, p->name) == 0)
			return p;
	return NULL;
}

/*
 * Sign operation is performed with the private key in the TPM.
 */
static int tpm_key_sign(struct tpm_key *tk,
			struct kernel_pkey_params *params,
			const void *in, void *out)
{
	struct tpm_buf tb;
	uint32_t keyhandle;
	uint8_t srkauth[SHA1_DIGEST_SIZE];
	uint8_t keyauth[SHA1_DIGEST_SIZE];
	void *asn1_wrapped = NULL;
	uint32_t in_len = params->in_len;
	int r;

	pr_devel("==>%s()\n", __func__);

	if (strcmp(params->encoding, "pkcs1"))
		return -ENOPKG;

	if (params->hash_algo) {
		const struct asn1_template *asn1 =
						lookup_asn1(params->hash_algo);

		if (!asn1)
			return -ENOPKG;

		/* request enough space for the ASN.1 template + input hash */
		asn1_wrapped = kzalloc(in_len + asn1->size, GFP_KERNEL);
		if (!asn1_wrapped)
			return -ENOMEM;

		/* Copy ASN.1 template, then the input */
		memcpy(asn1_wrapped, asn1->data, asn1->size);
		memcpy(asn1_wrapped + asn1->size, in, in_len);

		in = asn1_wrapped;
		in_len += asn1->size;
	}

	if (in_len > tk->key_len / 8 - 11) {
		r = -EOVERFLOW;
		goto error_free_asn1_wrapped;
	}

	r = tpm_buf_init(&tb, 0, 0);
	if (r)
		goto error_free_asn1_wrapped;

	/* TODO: Handle a non-all zero SRK authorization */
	memset(srkauth, 0, sizeof(srkauth));

	r = tpm_loadkey2(&tb, SRKHANDLE, srkauth,
			 tk->blob, tk->blob_len, &keyhandle);
	if (r < 0) {
		pr_devel("loadkey2 failed (%d)\n", r);
		goto error_free_tb;
	}

	/* TODO: Handle a non-all zero key authorization */
	memset(keyauth, 0, sizeof(keyauth));

	r = tpm_sign(&tb, keyhandle, keyauth, in, in_len, out, params->out_len);
	if (r < 0)
		pr_devel("tpm_sign failed (%d)\n", r);

	if (tpm_flushspecific(&tb, keyhandle) < 0)
		pr_devel("flushspecific failed (%d)\n", r);

error_free_tb:
	tpm_buf_destroy(&tb);
error_free_asn1_wrapped:
	kfree(asn1_wrapped);
	pr_devel("<==%s() = %d\n", __func__, r);
	return r;
}

/*
 * Do encryption, decryption and signing ops.
 */
static int tpm_key_eds_op(struct kernel_pkey_params *params,
			  const void *in, void *out)
{
	struct tpm_key *tk = params->key->payload.data[asym_crypto];
	int ret = -EOPNOTSUPP;

	/* Perform the encryption calculation. */
	switch (params->op) {
	case kernel_pkey_encrypt:
		ret = tpm_key_encrypt(tk, params, in, out);
		break;
	case kernel_pkey_decrypt:
		ret = tpm_key_decrypt(tk, params, in, out);
		break;
	case kernel_pkey_sign:
		ret = tpm_key_sign(tk, params, in, out);
		break;
	default:
		BUG();
	}

	return ret;
}

/*
 * Verify a signature using a public key.
 */
static int tpm_key_verify_signature(const struct key *key,
				    const struct public_key_signature *sig)
{
	const struct tpm_key *tk = key->payload.data[asym_crypto];
	struct crypto_wait cwait;
	struct crypto_akcipher *tfm;
	struct akcipher_request *req;
	struct scatterlist src_sg[2];
	char alg_name[CRYPTO_MAX_ALG_NAME];
	uint8_t der_pub_key[PUB_KEY_BUF_SIZE];
	uint32_t der_pub_key_len;
	int ret;

	pr_devel("==>%s()\n", __func__);

	BUG_ON(!tk);
	BUG_ON(!sig);
	BUG_ON(!sig->s);

	if (!sig->digest)
		return -ENOPKG;

	ret = determine_akcipher(sig->encoding, sig->hash_algo, alg_name);
	if (ret < 0)
		return ret;

	tfm = crypto_alloc_akcipher(alg_name, 0, 0);
	if (IS_ERR(tfm))
		return PTR_ERR(tfm);

	der_pub_key_len = derive_pub_key(tk->pub_key, tk->pub_key_len,
					 der_pub_key);

	ret = crypto_akcipher_set_pub_key(tfm, der_pub_key, der_pub_key_len);
	if (ret < 0)
		goto error_free_tfm;

	ret = -ENOMEM;
	req = akcipher_request_alloc(tfm, GFP_KERNEL);
	if (!req)
		goto error_free_tfm;

	sg_init_table(src_sg, 2);
	sg_set_buf(&src_sg[0], sig->s, sig->s_size);
	sg_set_buf(&src_sg[1], sig->digest, sig->digest_size);
	akcipher_request_set_crypt(req, src_sg, NULL, sig->s_size,
				   sig->digest_size);
	crypto_init_wait(&cwait);
	akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
				      CRYPTO_TFM_REQ_MAY_SLEEP,
				      crypto_req_done, &cwait);
	ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait);

	akcipher_request_free(req);
error_free_tfm:
	crypto_free_akcipher(tfm);
	pr_devel("<==%s() = %d\n", __func__, ret);
	if (WARN_ON_ONCE(ret > 0))
		ret = -EINVAL;
	return ret;
}

/*
 * Parse enough information out of TPM_KEY structure:
 * TPM_STRUCT_VER -> 4 bytes
 * TPM_KEY_USAGE -> 2 bytes
 * TPM_KEY_FLAGS -> 4 bytes
 * TPM_AUTH_DATA_USAGE -> 1 byte
 * TPM_KEY_PARMS -> variable
 * UINT32 PCRInfoSize -> 4 bytes
 * BYTE* -> PCRInfoSize bytes
 * TPM_STORE_PUBKEY
 * UINT32 encDataSize;
 * BYTE* -> encDataSize;
 *
 * TPM_KEY_PARMS:
 * TPM_ALGORITHM_ID -> 4 bytes
 * TPM_ENC_SCHEME -> 2 bytes
 * TPM_SIG_SCHEME -> 2 bytes
 * UINT32 parmSize -> 4 bytes
 * BYTE* -> variable
 */
static int extract_key_parameters(struct tpm_key *tk)
{
	const void *cur = tk->blob;
	uint32_t len = tk->blob_len;
	const void *pub_key;
	uint32_t sz;
	uint32_t key_len;

	if (len < 11)
		return -EBADMSG;

	/* Ensure this is a legacy key */
	if (get_unaligned_be16(cur + 4) != 0x0015)
		return -EBADMSG;

	/* Skip to TPM_KEY_PARMS */
	cur += 11;
	len -= 11;

	if (len < 12)
		return -EBADMSG;

	/* Make sure this is an RSA key */
	if (get_unaligned_be32(cur) != 0x00000001)
		return -EBADMSG;

	/* Make sure this is TPM_ES_RSAESPKCSv15 encoding scheme */
	if (get_unaligned_be16(cur + 4) != 0x0002)
		return -EBADMSG;

	/* Make sure this is TPM_SS_RSASSAPKCS1v15_DER signature scheme */
	if (get_unaligned_be16(cur + 6) != 0x0003)
		return -EBADMSG;

	sz = get_unaligned_be32(cur + 8);
	if (len < sz + 12)
		return -EBADMSG;

	/* Move to TPM_RSA_KEY_PARMS */
	len -= 12;
	cur += 12;

	/* Grab the RSA key length */
	key_len = get_unaligned_be32(cur);

	switch (key_len) {
	case 512:
	case 1024:
	case 1536:
	case 2048:
		break;
	default:
		return -EINVAL;
	}

	/* Move just past TPM_KEY_PARMS */
	cur += sz;
	len -= sz;

	if (len < 4)
		return -EBADMSG;

	sz = get_unaligned_be32(cur);
	if (len < 4 + sz)
		return -EBADMSG;

	/* Move to TPM_STORE_PUBKEY */
	cur += 4 + sz;
	len -= 4 + sz;

	/* Grab the size of the public key, it should jive with the key size */
	sz = get_unaligned_be32(cur);
	if (sz > 256)
		return -EINVAL;

	pub_key = cur + 4;

	tk->key_len = key_len;
	tk->pub_key = pub_key;
	tk->pub_key_len = sz;

	return 0;
}

/* Given the blob, parse it and load it into the TPM */
struct tpm_key *tpm_key_create(const void *blob, uint32_t blob_len)
{
	int r;
	struct tpm_key *tk;

	r = tpm_is_tpm2(NULL);
	if (r < 0)
		goto error;

	/* We don't support TPM2 yet */
	if (r > 0) {
		r = -ENODEV;
		goto error;
	}

	r = -ENOMEM;
	tk = kzalloc(sizeof(struct tpm_key), GFP_KERNEL);
	if (!tk)
		goto error;

	tk->blob = kmemdup(blob, blob_len, GFP_KERNEL);
	if (!tk->blob)
		goto error_memdup;

	tk->blob_len = blob_len;

	r = extract_key_parameters(tk);
	if (r < 0)
		goto error_extract;

	return tk;

error_extract:
	kfree(tk->blob);
	tk->blob_len = 0;
error_memdup:
	kfree(tk);
error:
	return ERR_PTR(r);
}
EXPORT_SYMBOL_GPL(tpm_key_create);

/*
 * TPM-based asymmetric key subtype
 */
struct asymmetric_key_subtype asym_tpm_subtype = {
	.owner			= THIS_MODULE,
	.name			= "asym_tpm",
	.name_len		= sizeof("asym_tpm") - 1,
	.describe		= asym_tpm_describe,
	.destroy		= asym_tpm_destroy,
	.query			= tpm_key_query,
	.eds_op			= tpm_key_eds_op,
	.verify_signature	= tpm_key_verify_signature,
};
EXPORT_SYMBOL_GPL(asym_tpm_subtype);

MODULE_DESCRIPTION("TPM based asymmetric key subtype");
MODULE_AUTHOR("Intel Corporation");
MODULE_LICENSE("GPL v2");