aboutsummaryrefslogtreecommitdiffstats
path: root/security/keys/encrypted_defined.c
blob: 0e558dcad92f8edabb57240babf1160a39a7db52 (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
/*
 * Copyright (C) 2010 IBM Corporation
 *
 * Author:
 * Mimi Zohar <zohar@us.ibm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 2 of the License.
 *
 * See Documentation/keys-trusted-encrypted.txt
 */

#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/parser.h>
#include <linux/string.h>
#include <keys/user-type.h>
#include <keys/trusted-type.h>
#include <keys/encrypted-type.h>
#include <linux/key-type.h>
#include <linux/random.h>
#include <linux/rcupdate.h>
#include <linux/scatterlist.h>
#include <linux/crypto.h>
#include <crypto/hash.h>
#include <crypto/sha.h>
#include <crypto/aes.h>

#include "encrypted_defined.h"

#define KEY_TRUSTED_PREFIX "trusted:"
#define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1)
#define KEY_USER_PREFIX "user:"
#define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1)

#define HASH_SIZE SHA256_DIGEST_SIZE
#define MAX_DATA_SIZE 4096
#define MIN_DATA_SIZE  20

static const char hash_alg[] = "sha256";
static const char hmac_alg[] = "hmac(sha256)";
static const char blkcipher_alg[] = "cbc(aes)";
static unsigned int ivsize;
static int blksize;

struct sdesc {
	struct shash_desc shash;
	char ctx[];
};

static struct crypto_shash *hashalg;
static struct crypto_shash *hmacalg;

enum {
	Opt_err = -1, Opt_new, Opt_load, Opt_update
};

static const match_table_t key_tokens = {
	{Opt_new, "new"},
	{Opt_load, "load"},
	{Opt_update, "update"},
	{Opt_err, NULL}
};

static int aes_get_sizes(void)
{
	struct crypto_blkcipher *tfm;

	tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(tfm)) {
		pr_err("encrypted_key: failed to alloc_cipher (%ld)\n",
		       PTR_ERR(tfm));
		return PTR_ERR(tfm);
	}
	ivsize = crypto_blkcipher_ivsize(tfm);
	blksize = crypto_blkcipher_blocksize(tfm);
	crypto_free_blkcipher(tfm);
	return 0;
}

/*
 * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key
 *
 * key-type:= "trusted:" | "encrypted:"
 * desc:= master-key description
 *
 * Verify that 'key-type' is valid and that 'desc' exists. On key update,
 * only the master key description is permitted to change, not the key-type.
 * The key-type remains constant.
 *
 * On success returns 0, otherwise -EINVAL.
 */
static int valid_master_desc(const char *new_desc, const char *orig_desc)
{
	if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) {
		if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN)
			goto out;
		if (orig_desc)
			if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN))
				goto out;
	} else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) {
		if (strlen(new_desc) == KEY_USER_PREFIX_LEN)
			goto out;
		if (orig_desc)
			if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN))
				goto out;
	} else
		goto out;
	return 0;
out:
	return -EINVAL;
}

/*
 * datablob_parse - parse the keyctl data
 *
 * datablob format:
 * new <master-key name> <decrypted data length>
 * load <master-key name> <decrypted data length> <encrypted iv + data>
 * update <new-master-key name>
 *
 * Tokenizes a copy of the keyctl data, returning a pointer to each token,
 * which is null terminated.
 *
 * On success returns 0, otherwise -EINVAL.
 */
static int datablob_parse(char *datablob, char **master_desc,
			  char **decrypted_datalen, char **hex_encoded_iv,
			  char **hex_encoded_data)
{
	substring_t args[MAX_OPT_ARGS];
	int ret = -EINVAL;
	int key_cmd;
	char *p;

	p = strsep(&datablob, " \t");
	if (!p)
		return ret;
	key_cmd = match_token(p, key_tokens, args);

	*master_desc = strsep(&datablob, " \t");
	if (!*master_desc)
		goto out;

	if (valid_master_desc(*master_desc, NULL) < 0)
		goto out;

	if (decrypted_datalen) {
		*decrypted_datalen = strsep(&datablob, " \t");
		if (!*decrypted_datalen)
			goto out;
	}

	switch (key_cmd) {
	case Opt_new:
		if (!decrypted_datalen)
			break;
		ret = 0;
		break;
	case Opt_load:
		if (!decrypted_datalen)
			break;
		*hex_encoded_iv = strsep(&datablob, " \t");
		if (!*hex_encoded_iv)
			break;
		*hex_encoded_data = *hex_encoded_iv + (2 * ivsize) + 2;
		ret = 0;
		break;
	case Opt_update:
		if (decrypted_datalen)
			break;
		ret = 0;
		break;
	case Opt_err:
		break;
	}
out:
	return ret;
}

/*
 * datablob_format - format as an ascii string, before copying to userspace
 */
static char *datablob_format(struct encrypted_key_payload *epayload,
			     size_t asciiblob_len)
{
	char *ascii_buf, *bufp;
	u8 *iv = epayload->iv;
	int len;
	int i;

	ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
	if (!ascii_buf)
		goto out;

	ascii_buf[asciiblob_len] = '\0';

	/* copy datablob master_desc and datalen strings */
	len = sprintf(ascii_buf, "%s %s ", epayload->master_desc,
		      epayload->datalen);

	/* convert the hex encoded iv, encrypted-data and HMAC to ascii */
	bufp = &ascii_buf[len];
	for (i = 0; i < (asciiblob_len - len) / 2; i++)
		bufp = pack_hex_byte(bufp, iv[i]);
out:
	return ascii_buf;
}

/*
 * request_trusted_key - request the trusted key
 *
 * Trusted keys are sealed to PCRs and other metadata. Although userspace
 * manages both trusted/encrypted key-types, like the encrypted key type
 * data, trusted key type data is not visible decrypted from userspace.
 */
static struct key *request_trusted_key(const char *trusted_desc,
				       u8 **master_key,
				       unsigned int *master_keylen)
{
	struct trusted_key_payload *tpayload;
	struct key *tkey;

	tkey = request_key(&key_type_trusted, trusted_desc, NULL);
	if (IS_ERR(tkey))
		goto error;

	down_read(&tkey->sem);
	tpayload = rcu_dereference(tkey->payload.data);
	*master_key = tpayload->key;
	*master_keylen = tpayload->key_len;
error:
	return tkey;
}

/*
 * request_user_key - request the user key
 *
 * Use a user provided key to encrypt/decrypt an encrypted-key.
 */
static struct key *request_user_key(const char *master_desc, u8 **master_key,
				    unsigned int *master_keylen)
{
	struct user_key_payload *upayload;
	struct key *ukey;

	ukey = request_key(&key_type_user, master_desc, NULL);
	if (IS_ERR(ukey))
		goto error;

	down_read(&ukey->sem);
	upayload = rcu_dereference(ukey->payload.data);
	*master_key = upayload->data;
	*master_keylen = upayload->datalen;
error:
	return ukey;
}

static struct sdesc *init_sdesc(struct crypto_shash *alg)
{
	struct sdesc *sdesc;
	int size;

	size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
	sdesc = kmalloc(size, GFP_KERNEL);
	if (!sdesc)
		return ERR_PTR(-ENOMEM);
	sdesc->shash.tfm = alg;
	sdesc->shash.flags = 0x0;
	return sdesc;
}

static int calc_hmac(u8 *digest, const u8 *key, const unsigned int keylen,
		     const u8 *buf, const unsigned int buflen)
{
	struct sdesc *sdesc;
	int ret;

	sdesc = init_sdesc(hmacalg);
	if (IS_ERR(sdesc)) {
		pr_info("encrypted_key: can't alloc %s\n", hmac_alg);
		return PTR_ERR(sdesc);
	}

	ret = crypto_shash_setkey(hmacalg, key, keylen);
	if (!ret)
		ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
	kfree(sdesc);
	return ret;
}

static int calc_hash(u8 *digest, const u8 *buf, const unsigned int buflen)
{
	struct sdesc *sdesc;
	int ret;

	sdesc = init_sdesc(hashalg);
	if (IS_ERR(sdesc)) {
		pr_info("encrypted_key: can't alloc %s\n", hash_alg);
		return PTR_ERR(sdesc);
	}

	ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
	kfree(sdesc);
	return ret;
}

enum derived_key_type { ENC_KEY, AUTH_KEY };

/* Derive authentication/encryption key from trusted key */
static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
			   const u8 *master_key,
			   const unsigned int master_keylen)
{
	u8 *derived_buf;
	unsigned int derived_buf_len;
	int ret;

	derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
	if (derived_buf_len < HASH_SIZE)
		derived_buf_len = HASH_SIZE;

	derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
	if (!derived_buf) {
		pr_err("encrypted_key: out of memory\n");
		return -ENOMEM;
	}
	if (key_type)
		strcpy(derived_buf, "AUTH_KEY");
	else
		strcpy(derived_buf, "ENC_KEY");

	memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
	       master_keylen);
	ret = calc_hash(derived_key, derived_buf, derived_buf_len);
	kfree(derived_buf);
	return ret;
}

static int init_blkcipher_desc(struct blkcipher_desc *desc, const u8 *key,
			       const unsigned int key_len, const u8 *iv,
			       const unsigned int ivsize)
{
	int ret;

	desc->tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(desc->tfm)) {
		pr_err("encrypted_key: failed to load %s transform (%ld)\n",
		       blkcipher_alg, PTR_ERR(desc->tfm));
		return PTR_ERR(desc->tfm);
	}
	desc->flags = 0;

	ret = crypto_blkcipher_setkey(desc->tfm, key, key_len);
	if (ret < 0) {
		pr_err("encrypted_key: failed to setkey (%d)\n", ret);
		crypto_free_blkcipher(desc->tfm);
		return ret;
	}
	crypto_blkcipher_set_iv(desc->tfm, iv, ivsize);
	return 0;
}

static struct key *request_master_key(struct encrypted_key_payload *epayload,
				      u8 **master_key,
				      unsigned int *master_keylen)
{
	struct key *mkey = NULL;

	if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
		     KEY_TRUSTED_PREFIX_LEN)) {
		mkey = request_trusted_key(epayload->master_desc +
					   KEY_TRUSTED_PREFIX_LEN,
					   master_key, master_keylen);
	} else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
			    KEY_USER_PREFIX_LEN)) {
		mkey = request_user_key(epayload->master_desc +
					KEY_USER_PREFIX_LEN,
					master_key, master_keylen);
	} else
		goto out;

	if (IS_ERR(mkey))
		pr_info("encrypted_key: key %s not found",
			epayload->master_desc);
	if (mkey)
		dump_master_key(*master_key, *master_keylen);
out:
	return mkey;
}

/* Before returning data to userspace, encrypt decrypted data. */
static int derived_key_encrypt(struct encrypted_key_payload *epayload,
			       const u8 *derived_key,
			       const unsigned int derived_keylen)
{
	struct scatterlist sg_in[2];
	struct scatterlist sg_out[1];
	struct blkcipher_desc desc;
	unsigned int encrypted_datalen;
	unsigned int padlen;
	char pad[16];
	int ret;

	encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
	padlen = encrypted_datalen - epayload->decrypted_datalen;

	ret = init_blkcipher_desc(&desc, derived_key, derived_keylen,
				  epayload->iv, ivsize);
	if (ret < 0)
		goto out;
	dump_decrypted_data(epayload);

	memset(pad, 0, sizeof pad);
	sg_init_table(sg_in, 2);
	sg_set_buf(&sg_in[0], epayload->decrypted_data,
		   epayload->decrypted_datalen);
	sg_set_buf(&sg_in[1], pad, padlen);

	sg_init_table(sg_out, 1);
	sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);

	ret = crypto_blkcipher_encrypt(&desc, sg_out, sg_in, encrypted_datalen);
	crypto_free_blkcipher(desc.tfm);
	if (ret < 0)
		pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
	else
		dump_encrypted_data(epayload, encrypted_datalen);
out:
	return ret;
}

static int datablob_hmac_append(struct encrypted_key_payload *epayload,
				const u8 *master_key,
				const unsigned int master_keylen)
{
	u8 derived_key[HASH_SIZE];
	u8 *digest;
	int ret;

	ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
	if (ret < 0)
		goto out;

	digest = epayload->master_desc + epayload->datablob_len;
	ret = calc_hmac(digest, derived_key, sizeof derived_key,
			epayload->master_desc, epayload->datablob_len);
	if (!ret)
		dump_hmac(NULL, digest, HASH_SIZE);
out:
	return ret;
}

/* verify HMAC before decrypting encrypted key */
static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
				const u8 *master_key,
				const unsigned int master_keylen)
{
	u8 derived_key[HASH_SIZE];
	u8 digest[HASH_SIZE];
	int ret;

	ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
	if (ret < 0)
		goto out;

	ret = calc_hmac(digest, derived_key, sizeof derived_key,
			epayload->master_desc, epayload->datablob_len);
	if (ret < 0)
		goto out;
	ret = memcmp(digest, epayload->master_desc + epayload->datablob_len,
		     sizeof digest);
	if (ret) {
		ret = -EINVAL;
		dump_hmac("datablob",
			  epayload->master_desc + epayload->datablob_len,
			  HASH_SIZE);
		dump_hmac("calc", digest, HASH_SIZE);
	}
out:
	return ret;
}

static int derived_key_decrypt(struct encrypted_key_payload *epayload,
			       const u8 *derived_key,
			       const unsigned int derived_keylen)
{
	struct scatterlist sg_in[1];
	struct scatterlist sg_out[2];
	struct blkcipher_desc desc;
	unsigned int encrypted_datalen;
	char pad[16];
	int ret;

	encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
	ret = init_blkcipher_desc(&desc, derived_key, derived_keylen,
				  epayload->iv, ivsize);
	if (ret < 0)
		goto out;
	dump_encrypted_data(epayload, encrypted_datalen);

	memset(pad, 0, sizeof pad);
	sg_init_table(sg_in, 1);
	sg_init_table(sg_out, 2);
	sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
	sg_set_buf(&sg_out[0], epayload->decrypted_data,
		   (unsigned int)epayload->decrypted_datalen);
	sg_set_buf(&sg_out[1], pad, sizeof pad);

	ret = crypto_blkcipher_decrypt(&desc, sg_out, sg_in, encrypted_datalen);
	crypto_free_blkcipher(desc.tfm);
	if (ret < 0)
		goto out;
	dump_decrypted_data(epayload);
out:
	return ret;
}

/* Allocate memory for decrypted key and datablob. */
static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
							 const char *master_desc,
							 const char *datalen)
{
	struct encrypted_key_payload *epayload = NULL;
	unsigned short datablob_len;
	unsigned short decrypted_datalen;
	unsigned int encrypted_datalen;
	long dlen;
	int ret;

	ret = strict_strtol(datalen, 10, &dlen);
	if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
		return ERR_PTR(-EINVAL);

	decrypted_datalen = dlen;
	encrypted_datalen = roundup(decrypted_datalen, blksize);

	datablob_len = strlen(master_desc) + 1 + strlen(datalen) + 1
	    + ivsize + 1 + encrypted_datalen;

	ret = key_payload_reserve(key, decrypted_datalen + datablob_len
				  + HASH_SIZE + 1);
	if (ret < 0)
		return ERR_PTR(ret);

	epayload = kzalloc(sizeof(*epayload) + decrypted_datalen +
			   datablob_len + HASH_SIZE + 1, GFP_KERNEL);
	if (!epayload)
		return ERR_PTR(-ENOMEM);

	epayload->decrypted_datalen = decrypted_datalen;
	epayload->datablob_len = datablob_len;
	return epayload;
}

static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
				 const char *hex_encoded_iv,
				 const char *hex_encoded_data)
{
	struct key *mkey;
	u8 derived_key[HASH_SIZE];
	u8 *master_key;
	u8 *hmac;
	unsigned int master_keylen;
	unsigned int encrypted_datalen;
	int ret;

	encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
	hex2bin(epayload->iv, hex_encoded_iv, ivsize);
	hex2bin(epayload->encrypted_data, hex_encoded_data, encrypted_datalen);

	hmac = epayload->master_desc + epayload->datablob_len;
	hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), HASH_SIZE);

	mkey = request_master_key(epayload, &master_key, &master_keylen);
	if (IS_ERR(mkey))
		return PTR_ERR(mkey);

	ret = datablob_hmac_verify(epayload, master_key, master_keylen);
	if (ret < 0) {
		pr_err("encrypted_key: bad hmac (%d)\n", ret);
		goto out;
	}

	ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
	if (ret < 0)
		goto out;

	ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
	if (ret < 0)
		pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
out:
	up_read(&mkey->sem);
	key_put(mkey);
	return ret;
}

static void __ekey_init(struct encrypted_key_payload *epayload,
			const char *master_desc, const char *datalen)
{
	epayload->master_desc = epayload->decrypted_data
	    + epayload->decrypted_datalen;
	epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
	epayload->iv = epayload->datalen + strlen(datalen) + 1;
	epayload->encrypted_data = epayload->iv + ivsize + 1;

	memcpy(epayload->master_desc, master_desc, strlen(master_desc));
	memcpy(epayload->datalen, datalen, strlen(datalen));
}

/*
 * encrypted_init - initialize an encrypted key
 *
 * For a new key, use a random number for both the iv and data
 * itself.  For an old key, decrypt the hex encoded data.
 */
static int encrypted_init(struct encrypted_key_payload *epayload,
			  const char *master_desc, const char *datalen,
			  const char *hex_encoded_iv,
			  const char *hex_encoded_data)
{
	int ret = 0;

	__ekey_init(epayload, master_desc, datalen);
	if (!hex_encoded_data) {
		get_random_bytes(epayload->iv, ivsize);

		get_random_bytes(epayload->decrypted_data,
				 epayload->decrypted_datalen);
	} else
		ret = encrypted_key_decrypt(epayload, hex_encoded_iv,
					    hex_encoded_data);
	return ret;
}

/*
 * encrypted_instantiate - instantiate an encrypted key
 *
 * Decrypt an existing encrypted datablob or create a new encrypted key
 * based on a kernel random number.
 *
 * On success, return 0. Otherwise return errno.
 */
static int encrypted_instantiate(struct key *key, const void *data,
				 size_t datalen)
{
	struct encrypted_key_payload *epayload = NULL;
	char *datablob = NULL;
	char *master_desc = NULL;
	char *decrypted_datalen = NULL;
	char *hex_encoded_iv = NULL;
	char *hex_encoded_data = NULL;
	int ret;

	if (datalen <= 0 || datalen > 32767 || !data)
		return -EINVAL;

	datablob = kmalloc(datalen + 1, GFP_KERNEL);
	if (!datablob)
		return -ENOMEM;
	datablob[datalen] = 0;
	memcpy(datablob, data, datalen);
	ret = datablob_parse(datablob, &master_desc, &decrypted_datalen,
			     &hex_encoded_iv, &hex_encoded_data);
	if (ret < 0)
		goto out;

	epayload = encrypted_key_alloc(key, master_desc, decrypted_datalen);
	if (IS_ERR(epayload)) {
		ret = PTR_ERR(epayload);
		goto out;
	}
	ret = encrypted_init(epayload, master_desc, decrypted_datalen,
			     hex_encoded_iv, hex_encoded_data);
	if (ret < 0) {
		kfree(epayload);
		goto out;
	}

	rcu_assign_pointer(key->payload.data, epayload);
out:
	kfree(datablob);
	return ret;
}

static void encrypted_rcu_free(struct rcu_head *rcu)
{
	struct encrypted_key_payload *epayload;

	epayload = container_of(rcu, struct encrypted_key_payload, rcu);
	memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
	kfree(epayload);
}

/*
 * encrypted_update - update the master key description
 *
 * Change the master key description for an existing encrypted key.
 * The next read will return an encrypted datablob using the new
 * master key description.
 *
 * On success, return 0. Otherwise return errno.
 */
static int encrypted_update(struct key *key, const void *data, size_t datalen)
{
	struct encrypted_key_payload *epayload = key->payload.data;
	struct encrypted_key_payload *new_epayload;
	char *buf;
	char *new_master_desc = NULL;
	int ret = 0;

	if (datalen <= 0 || datalen > 32767 || !data)
		return -EINVAL;

	buf = kmalloc(datalen + 1, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	buf[datalen] = 0;
	memcpy(buf, data, datalen);
	ret = datablob_parse(buf, &new_master_desc, NULL, NULL, NULL);
	if (ret < 0)
		goto out;

	ret = valid_master_desc(new_master_desc, epayload->master_desc);
	if (ret < 0)
		goto out;

	new_epayload = encrypted_key_alloc(key, new_master_desc,
					   epayload->datalen);
	if (IS_ERR(new_epayload)) {
		ret = PTR_ERR(new_epayload);
		goto out;
	}

	__ekey_init(new_epayload, new_master_desc, epayload->datalen);

	memcpy(new_epayload->iv, epayload->iv, ivsize);
	memcpy(new_epayload->decrypted_data, epayload->decrypted_data,
	       epayload->decrypted_datalen);

	rcu_assign_pointer(key->payload.data, new_epayload);
	call_rcu(&epayload->rcu, encrypted_rcu_free);
out:
	kfree(buf);
	return ret;
}

/*
 * encrypted_read - format and copy the encrypted data to userspace
 *
 * The resulting datablob format is:
 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
 *
 * On success, return to userspace the encrypted key datablob size.
 */
static long encrypted_read(const struct key *key, char __user *buffer,
			   size_t buflen)
{
	struct encrypted_key_payload *epayload;
	struct key *mkey;
	u8 *master_key;
	unsigned int master_keylen;
	char derived_key[HASH_SIZE];
	char *ascii_buf;
	size_t asciiblob_len;
	int ret;

	epayload = rcu_dereference_protected(key->payload.data,
				  rwsem_is_locked(&((struct key *)key)->sem));

	/* returns the hex encoded iv, encrypted-data, and hmac as ascii */
	asciiblob_len = epayload->datablob_len + ivsize + 1
	    + roundup(epayload->decrypted_datalen, blksize)
	    + (HASH_SIZE * 2);

	if (!buffer || buflen < asciiblob_len)
		return asciiblob_len;

	mkey = request_master_key(epayload, &master_key, &master_keylen);
	if (IS_ERR(mkey))
		return PTR_ERR(mkey);

	ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
	if (ret < 0)
		goto out;

	ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
	if (ret < 0)
		goto out;

	ret = datablob_hmac_append(epayload, master_key, master_keylen);
	if (ret < 0)
		goto out;

	ascii_buf = datablob_format(epayload, asciiblob_len);
	if (!ascii_buf) {
		ret = -ENOMEM;
		goto out;
	}

	up_read(&mkey->sem);
	key_put(mkey);

	if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0)
		ret = -EFAULT;
	kfree(ascii_buf);

	return asciiblob_len;
out:
	up_read(&mkey->sem);
	key_put(mkey);
	return ret;
}

/*
 * encrypted_destroy - before freeing the key, clear the decrypted data
 *
 * Before freeing the key, clear the memory containing the decrypted
 * key data.
 */
static void encrypted_destroy(struct key *key)
{
	struct encrypted_key_payload *epayload = key->payload.data;

	if (!epayload)
		return;

	memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
	kfree(key->payload.data);
}

struct key_type key_type_encrypted = {
	.name = "encrypted",
	.instantiate = encrypted_instantiate,
	.update = encrypted_update,
	.match = user_match,
	.destroy = encrypted_destroy,
	.describe = user_describe,
	.read = encrypted_read,
};
EXPORT_SYMBOL_GPL(key_type_encrypted);

static void encrypted_shash_release(void)
{
	if (hashalg)
		crypto_free_shash(hashalg);
	if (hmacalg)
		crypto_free_shash(hmacalg);
}

static int __init encrypted_shash_alloc(void)
{
	int ret;

	hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(hmacalg)) {
		pr_info("encrypted_key: could not allocate crypto %s\n",
			hmac_alg);
		return PTR_ERR(hmacalg);
	}

	hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(hashalg)) {
		pr_info("encrypted_key: could not allocate crypto %s\n",
			hash_alg);
		ret = PTR_ERR(hashalg);
		goto hashalg_fail;
	}

	return 0;

hashalg_fail:
	crypto_free_shash(hmacalg);
	return ret;
}

static int __init init_encrypted(void)
{
	int ret;

	ret = encrypted_shash_alloc();
	if (ret < 0)
		return ret;
	ret = register_key_type(&key_type_encrypted);
	if (ret < 0)
		goto out;
	return aes_get_sizes();
out:
	encrypted_shash_release();
	return ret;

}

static void __exit cleanup_encrypted(void)
{
	encrypted_shash_release();
	unregister_key_type(&key_type_encrypted);
}

late_initcall(init_encrypted);
module_exit(cleanup_encrypted);

MODULE_LICENSE("GPL");

Privacy Policy