forked from analogdevicesinc/linux
-
Notifications
You must be signed in to change notification settings - Fork 3
/
keystore.c
2544 lines (2449 loc) · 79.3 KB
/
keystore.c
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
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/**
* eCryptfs: Linux filesystem encryption layer
* In-kernel key management code. Includes functions to parse and
* write authentication token-related packets with the underlying
* file.
*
* Copyright (C) 2004-2006 International Business Machines Corp.
* Author(s): Michael A. Halcrow <[email protected]>
* Michael C. Thompson <[email protected]>
* Trevor S. Highland <[email protected]>
*
* 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; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
* 02111-1307, USA.
*/
#include <crypto/hash.h>
#include <crypto/skcipher.h>
#include <linux/string.h>
#include <linux/pagemap.h>
#include <linux/key.h>
#include <linux/random.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include "ecryptfs_kernel.h"
/**
* request_key returned an error instead of a valid key address;
* determine the type of error, make appropriate log entries, and
* return an error code.
*/
static int process_request_key_err(long err_code)
{
int rc = 0;
switch (err_code) {
case -ENOKEY:
ecryptfs_printk(KERN_WARNING, "No key\n");
rc = -ENOENT;
break;
case -EKEYEXPIRED:
ecryptfs_printk(KERN_WARNING, "Key expired\n");
rc = -ETIME;
break;
case -EKEYREVOKED:
ecryptfs_printk(KERN_WARNING, "Key revoked\n");
rc = -EINVAL;
break;
default:
ecryptfs_printk(KERN_WARNING, "Unknown error code: "
"[0x%.16lx]\n", err_code);
rc = -EINVAL;
}
return rc;
}
static int process_find_global_auth_tok_for_sig_err(int err_code)
{
int rc = err_code;
switch (err_code) {
case -ENOENT:
ecryptfs_printk(KERN_WARNING, "Missing auth tok\n");
break;
case -EINVAL:
ecryptfs_printk(KERN_WARNING, "Invalid auth tok\n");
break;
default:
rc = process_request_key_err(err_code);
break;
}
return rc;
}
/**
* ecryptfs_parse_packet_length
* @data: Pointer to memory containing length at offset
* @size: This function writes the decoded size to this memory
* address; zero on error
* @length_size: The number of bytes occupied by the encoded length
*
* Returns zero on success; non-zero on error
*/
int ecryptfs_parse_packet_length(unsigned char *data, size_t *size,
size_t *length_size)
{
int rc = 0;
(*length_size) = 0;
(*size) = 0;
if (data[0] < 192) {
/* One-byte length */
(*size) = data[0];
(*length_size) = 1;
} else if (data[0] < 224) {
/* Two-byte length */
(*size) = (data[0] - 192) * 256;
(*size) += data[1] + 192;
(*length_size) = 2;
} else if (data[0] == 255) {
/* If support is added, adjust ECRYPTFS_MAX_PKT_LEN_SIZE */
ecryptfs_printk(KERN_ERR, "Five-byte packet length not "
"supported\n");
rc = -EINVAL;
goto out;
} else {
ecryptfs_printk(KERN_ERR, "Error parsing packet length\n");
rc = -EINVAL;
goto out;
}
out:
return rc;
}
/**
* ecryptfs_write_packet_length
* @dest: The byte array target into which to write the length. Must
* have at least ECRYPTFS_MAX_PKT_LEN_SIZE bytes allocated.
* @size: The length to write.
* @packet_size_length: The number of bytes used to encode the packet
* length is written to this address.
*
* Returns zero on success; non-zero on error.
*/
int ecryptfs_write_packet_length(char *dest, size_t size,
size_t *packet_size_length)
{
int rc = 0;
if (size < 192) {
dest[0] = size;
(*packet_size_length) = 1;
} else if (size < 65536) {
dest[0] = (((size - 192) / 256) + 192);
dest[1] = ((size - 192) % 256);
(*packet_size_length) = 2;
} else {
/* If support is added, adjust ECRYPTFS_MAX_PKT_LEN_SIZE */
rc = -EINVAL;
ecryptfs_printk(KERN_WARNING,
"Unsupported packet size: [%zd]\n", size);
}
return rc;
}
static int
write_tag_64_packet(char *signature, struct ecryptfs_session_key *session_key,
char **packet, size_t *packet_len)
{
size_t i = 0;
size_t data_len;
size_t packet_size_len;
char *message;
int rc;
/*
* ***** TAG 64 Packet Format *****
* | Content Type | 1 byte |
* | Key Identifier Size | 1 or 2 bytes |
* | Key Identifier | arbitrary |
* | Encrypted File Encryption Key Size | 1 or 2 bytes |
* | Encrypted File Encryption Key | arbitrary |
*/
data_len = (5 + ECRYPTFS_SIG_SIZE_HEX
+ session_key->encrypted_key_size);
*packet = kmalloc(data_len, GFP_KERNEL);
message = *packet;
if (!message) {
ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
rc = -ENOMEM;
goto out;
}
message[i++] = ECRYPTFS_TAG_64_PACKET_TYPE;
rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
&packet_size_len);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
"header; cannot generate packet length\n");
goto out;
}
i += packet_size_len;
memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
i += ECRYPTFS_SIG_SIZE_HEX;
rc = ecryptfs_write_packet_length(&message[i],
session_key->encrypted_key_size,
&packet_size_len);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
"header; cannot generate packet length\n");
goto out;
}
i += packet_size_len;
memcpy(&message[i], session_key->encrypted_key,
session_key->encrypted_key_size);
i += session_key->encrypted_key_size;
*packet_len = i;
out:
return rc;
}
static int
parse_tag_65_packet(struct ecryptfs_session_key *session_key, u8 *cipher_code,
struct ecryptfs_message *msg)
{
size_t i = 0;
char *data;
size_t data_len;
size_t m_size;
size_t message_len;
u16 checksum = 0;
u16 expected_checksum = 0;
int rc;
/*
* ***** TAG 65 Packet Format *****
* | Content Type | 1 byte |
* | Status Indicator | 1 byte |
* | File Encryption Key Size | 1 or 2 bytes |
* | File Encryption Key | arbitrary |
*/
message_len = msg->data_len;
data = msg->data;
if (message_len < 4) {
rc = -EIO;
goto out;
}
if (data[i++] != ECRYPTFS_TAG_65_PACKET_TYPE) {
ecryptfs_printk(KERN_ERR, "Type should be ECRYPTFS_TAG_65\n");
rc = -EIO;
goto out;
}
if (data[i++]) {
ecryptfs_printk(KERN_ERR, "Status indicator has non-zero value "
"[%d]\n", data[i-1]);
rc = -EIO;
goto out;
}
rc = ecryptfs_parse_packet_length(&data[i], &m_size, &data_len);
if (rc) {
ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
"rc = [%d]\n", rc);
goto out;
}
i += data_len;
if (message_len < (i + m_size)) {
ecryptfs_printk(KERN_ERR, "The message received from ecryptfsd "
"is shorter than expected\n");
rc = -EIO;
goto out;
}
if (m_size < 3) {
ecryptfs_printk(KERN_ERR,
"The decrypted key is not long enough to "
"include a cipher code and checksum\n");
rc = -EIO;
goto out;
}
*cipher_code = data[i++];
/* The decrypted key includes 1 byte cipher code and 2 byte checksum */
session_key->decrypted_key_size = m_size - 3;
if (session_key->decrypted_key_size > ECRYPTFS_MAX_KEY_BYTES) {
ecryptfs_printk(KERN_ERR, "key_size [%d] larger than "
"the maximum key size [%d]\n",
session_key->decrypted_key_size,
ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
rc = -EIO;
goto out;
}
memcpy(session_key->decrypted_key, &data[i],
session_key->decrypted_key_size);
i += session_key->decrypted_key_size;
expected_checksum += (unsigned char)(data[i++]) << 8;
expected_checksum += (unsigned char)(data[i++]);
for (i = 0; i < session_key->decrypted_key_size; i++)
checksum += session_key->decrypted_key[i];
if (expected_checksum != checksum) {
ecryptfs_printk(KERN_ERR, "Invalid checksum for file "
"encryption key; expected [%x]; calculated "
"[%x]\n", expected_checksum, checksum);
rc = -EIO;
}
out:
return rc;
}
static int
write_tag_66_packet(char *signature, u8 cipher_code,
struct ecryptfs_crypt_stat *crypt_stat, char **packet,
size_t *packet_len)
{
size_t i = 0;
size_t j;
size_t data_len;
size_t checksum = 0;
size_t packet_size_len;
char *message;
int rc;
/*
* ***** TAG 66 Packet Format *****
* | Content Type | 1 byte |
* | Key Identifier Size | 1 or 2 bytes |
* | Key Identifier | arbitrary |
* | File Encryption Key Size | 1 or 2 bytes |
* | File Encryption Key | arbitrary |
*/
data_len = (5 + ECRYPTFS_SIG_SIZE_HEX + crypt_stat->key_size);
*packet = kmalloc(data_len, GFP_KERNEL);
message = *packet;
if (!message) {
ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
rc = -ENOMEM;
goto out;
}
message[i++] = ECRYPTFS_TAG_66_PACKET_TYPE;
rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
&packet_size_len);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
"header; cannot generate packet length\n");
goto out;
}
i += packet_size_len;
memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
i += ECRYPTFS_SIG_SIZE_HEX;
/* The encrypted key includes 1 byte cipher code and 2 byte checksum */
rc = ecryptfs_write_packet_length(&message[i], crypt_stat->key_size + 3,
&packet_size_len);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
"header; cannot generate packet length\n");
goto out;
}
i += packet_size_len;
message[i++] = cipher_code;
memcpy(&message[i], crypt_stat->key, crypt_stat->key_size);
i += crypt_stat->key_size;
for (j = 0; j < crypt_stat->key_size; j++)
checksum += crypt_stat->key[j];
message[i++] = (checksum / 256) % 256;
message[i++] = (checksum % 256);
*packet_len = i;
out:
return rc;
}
static int
parse_tag_67_packet(struct ecryptfs_key_record *key_rec,
struct ecryptfs_message *msg)
{
size_t i = 0;
char *data;
size_t data_len;
size_t message_len;
int rc;
/*
* ***** TAG 65 Packet Format *****
* | Content Type | 1 byte |
* | Status Indicator | 1 byte |
* | Encrypted File Encryption Key Size | 1 or 2 bytes |
* | Encrypted File Encryption Key | arbitrary |
*/
message_len = msg->data_len;
data = msg->data;
/* verify that everything through the encrypted FEK size is present */
if (message_len < 4) {
rc = -EIO;
printk(KERN_ERR "%s: message_len is [%zd]; minimum acceptable "
"message length is [%d]\n", __func__, message_len, 4);
goto out;
}
if (data[i++] != ECRYPTFS_TAG_67_PACKET_TYPE) {
rc = -EIO;
printk(KERN_ERR "%s: Type should be ECRYPTFS_TAG_67\n",
__func__);
goto out;
}
if (data[i++]) {
rc = -EIO;
printk(KERN_ERR "%s: Status indicator has non zero "
"value [%d]\n", __func__, data[i-1]);
goto out;
}
rc = ecryptfs_parse_packet_length(&data[i], &key_rec->enc_key_size,
&data_len);
if (rc) {
ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
"rc = [%d]\n", rc);
goto out;
}
i += data_len;
if (message_len < (i + key_rec->enc_key_size)) {
rc = -EIO;
printk(KERN_ERR "%s: message_len [%zd]; max len is [%zd]\n",
__func__, message_len, (i + key_rec->enc_key_size));
goto out;
}
if (key_rec->enc_key_size > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
rc = -EIO;
printk(KERN_ERR "%s: Encrypted key_size [%zd] larger than "
"the maximum key size [%d]\n", __func__,
key_rec->enc_key_size,
ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
goto out;
}
memcpy(key_rec->enc_key, &data[i], key_rec->enc_key_size);
out:
return rc;
}
/**
* ecryptfs_verify_version
* @version: The version number to confirm
*
* Returns zero on good version; non-zero otherwise
*/
static int ecryptfs_verify_version(u16 version)
{
int rc = 0;
unsigned char major;
unsigned char minor;
major = ((version >> 8) & 0xFF);
minor = (version & 0xFF);
if (major != ECRYPTFS_VERSION_MAJOR) {
ecryptfs_printk(KERN_ERR, "Major version number mismatch. "
"Expected [%d]; got [%d]\n",
ECRYPTFS_VERSION_MAJOR, major);
rc = -EINVAL;
goto out;
}
if (minor != ECRYPTFS_VERSION_MINOR) {
ecryptfs_printk(KERN_ERR, "Minor version number mismatch. "
"Expected [%d]; got [%d]\n",
ECRYPTFS_VERSION_MINOR, minor);
rc = -EINVAL;
goto out;
}
out:
return rc;
}
/**
* ecryptfs_verify_auth_tok_from_key
* @auth_tok_key: key containing the authentication token
* @auth_tok: authentication token
*
* Returns zero on valid auth tok; -EINVAL if the payload is invalid; or
* -EKEYREVOKED if the key was revoked before we acquired its semaphore.
*/
static int
ecryptfs_verify_auth_tok_from_key(struct key *auth_tok_key,
struct ecryptfs_auth_tok **auth_tok)
{
int rc = 0;
(*auth_tok) = ecryptfs_get_key_payload_data(auth_tok_key);
if (IS_ERR(*auth_tok)) {
rc = PTR_ERR(*auth_tok);
*auth_tok = NULL;
goto out;
}
if (ecryptfs_verify_version((*auth_tok)->version)) {
printk(KERN_ERR "Data structure version mismatch. Userspace "
"tools must match eCryptfs kernel module with major "
"version [%d] and minor version [%d]\n",
ECRYPTFS_VERSION_MAJOR, ECRYPTFS_VERSION_MINOR);
rc = -EINVAL;
goto out;
}
if ((*auth_tok)->token_type != ECRYPTFS_PASSWORD
&& (*auth_tok)->token_type != ECRYPTFS_PRIVATE_KEY) {
printk(KERN_ERR "Invalid auth_tok structure "
"returned from key query\n");
rc = -EINVAL;
goto out;
}
out:
return rc;
}
static int
ecryptfs_find_global_auth_tok_for_sig(
struct key **auth_tok_key,
struct ecryptfs_auth_tok **auth_tok,
struct ecryptfs_mount_crypt_stat *mount_crypt_stat, char *sig)
{
struct ecryptfs_global_auth_tok *walker;
int rc = 0;
(*auth_tok_key) = NULL;
(*auth_tok) = NULL;
mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
list_for_each_entry(walker,
&mount_crypt_stat->global_auth_tok_list,
mount_crypt_stat_list) {
if (memcmp(walker->sig, sig, ECRYPTFS_SIG_SIZE_HEX))
continue;
if (walker->flags & ECRYPTFS_AUTH_TOK_INVALID) {
rc = -EINVAL;
goto out;
}
rc = key_validate(walker->global_auth_tok_key);
if (rc) {
if (rc == -EKEYEXPIRED)
goto out;
goto out_invalid_auth_tok;
}
down_write(&(walker->global_auth_tok_key->sem));
rc = ecryptfs_verify_auth_tok_from_key(
walker->global_auth_tok_key, auth_tok);
if (rc)
goto out_invalid_auth_tok_unlock;
(*auth_tok_key) = walker->global_auth_tok_key;
key_get(*auth_tok_key);
goto out;
}
rc = -ENOENT;
goto out;
out_invalid_auth_tok_unlock:
up_write(&(walker->global_auth_tok_key->sem));
out_invalid_auth_tok:
printk(KERN_WARNING "Invalidating auth tok with sig = [%s]\n", sig);
walker->flags |= ECRYPTFS_AUTH_TOK_INVALID;
key_put(walker->global_auth_tok_key);
walker->global_auth_tok_key = NULL;
out:
mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
return rc;
}
/**
* ecryptfs_find_auth_tok_for_sig
* @auth_tok: Set to the matching auth_tok; NULL if not found
* @crypt_stat: inode crypt_stat crypto context
* @sig: Sig of auth_tok to find
*
* For now, this function simply looks at the registered auth_tok's
* linked off the mount_crypt_stat, so all the auth_toks that can be
* used must be registered at mount time. This function could
* potentially try a lot harder to find auth_tok's (e.g., by calling
* out to ecryptfsd to dynamically retrieve an auth_tok object) so
* that static registration of auth_tok's will no longer be necessary.
*
* Returns zero on no error; non-zero on error
*/
static int
ecryptfs_find_auth_tok_for_sig(
struct key **auth_tok_key,
struct ecryptfs_auth_tok **auth_tok,
struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
char *sig)
{
int rc = 0;
rc = ecryptfs_find_global_auth_tok_for_sig(auth_tok_key, auth_tok,
mount_crypt_stat, sig);
if (rc == -ENOENT) {
/* if the flag ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY is set in the
* mount_crypt_stat structure, we prevent to use auth toks that
* are not inserted through the ecryptfs_add_global_auth_tok
* function.
*/
if (mount_crypt_stat->flags
& ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
return -EINVAL;
rc = ecryptfs_keyring_auth_tok_for_sig(auth_tok_key, auth_tok,
sig);
}
return rc;
}
/**
* write_tag_70_packet can gobble a lot of stack space. We stuff most
* of the function's parameters in a kmalloc'd struct to help reduce
* eCryptfs' overall stack usage.
*/
struct ecryptfs_write_tag_70_packet_silly_stack {
u8 cipher_code;
size_t max_packet_size;
size_t packet_size_len;
size_t block_aligned_filename_size;
size_t block_size;
size_t i;
size_t j;
size_t num_rand_bytes;
struct mutex *tfm_mutex;
char *block_aligned_filename;
struct ecryptfs_auth_tok *auth_tok;
struct scatterlist src_sg[2];
struct scatterlist dst_sg[2];
struct crypto_skcipher *skcipher_tfm;
struct skcipher_request *skcipher_req;
char iv[ECRYPTFS_MAX_IV_BYTES];
char hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
char tmp_hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
struct crypto_shash *hash_tfm;
struct shash_desc *hash_desc;
};
/**
* write_tag_70_packet - Write encrypted filename (EFN) packet against FNEK
* @filename: NULL-terminated filename string
*
* This is the simplest mechanism for achieving filename encryption in
* eCryptfs. It encrypts the given filename with the mount-wide
* filename encryption key (FNEK) and stores it in a packet to @dest,
* which the callee will encode and write directly into the dentry
* name.
*/
int
ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
size_t *packet_size,
struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
char *filename, size_t filename_size)
{
struct ecryptfs_write_tag_70_packet_silly_stack *s;
struct key *auth_tok_key = NULL;
int rc = 0;
s = kzalloc(sizeof(*s), GFP_KERNEL);
if (!s)
return -ENOMEM;
(*packet_size) = 0;
rc = ecryptfs_find_auth_tok_for_sig(
&auth_tok_key,
&s->auth_tok, mount_crypt_stat,
mount_crypt_stat->global_default_fnek_sig);
if (rc) {
printk(KERN_ERR "%s: Error attempting to find auth tok for "
"fnek sig [%s]; rc = [%d]\n", __func__,
mount_crypt_stat->global_default_fnek_sig, rc);
goto out;
}
rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(
&s->skcipher_tfm,
&s->tfm_mutex, mount_crypt_stat->global_default_fn_cipher_name);
if (unlikely(rc)) {
printk(KERN_ERR "Internal error whilst attempting to get "
"tfm and mutex for cipher name [%s]; rc = [%d]\n",
mount_crypt_stat->global_default_fn_cipher_name, rc);
goto out;
}
mutex_lock(s->tfm_mutex);
s->block_size = crypto_skcipher_blocksize(s->skcipher_tfm);
/* Plus one for the \0 separator between the random prefix
* and the plaintext filename */
s->num_rand_bytes = (ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES + 1);
s->block_aligned_filename_size = (s->num_rand_bytes + filename_size);
if ((s->block_aligned_filename_size % s->block_size) != 0) {
s->num_rand_bytes += (s->block_size
- (s->block_aligned_filename_size
% s->block_size));
s->block_aligned_filename_size = (s->num_rand_bytes
+ filename_size);
}
/* Octet 0: Tag 70 identifier
* Octets 1-N1: Tag 70 packet size (includes cipher identifier
* and block-aligned encrypted filename size)
* Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
* Octet N2-N3: Cipher identifier (1 octet)
* Octets N3-N4: Block-aligned encrypted filename
* - Consists of a minimum number of random characters, a \0
* separator, and then the filename */
s->max_packet_size = (ECRYPTFS_TAG_70_MAX_METADATA_SIZE
+ s->block_aligned_filename_size);
if (!dest) {
(*packet_size) = s->max_packet_size;
goto out_unlock;
}
if (s->max_packet_size > (*remaining_bytes)) {
printk(KERN_WARNING "%s: Require [%zd] bytes to write; only "
"[%zd] available\n", __func__, s->max_packet_size,
(*remaining_bytes));
rc = -EINVAL;
goto out_unlock;
}
s->skcipher_req = skcipher_request_alloc(s->skcipher_tfm, GFP_KERNEL);
if (!s->skcipher_req) {
printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
"skcipher_request_alloc for %s\n", __func__,
crypto_skcipher_driver_name(s->skcipher_tfm));
rc = -ENOMEM;
goto out_unlock;
}
skcipher_request_set_callback(s->skcipher_req,
CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
s->block_aligned_filename = kzalloc(s->block_aligned_filename_size,
GFP_KERNEL);
if (!s->block_aligned_filename) {
rc = -ENOMEM;
goto out_unlock;
}
dest[s->i++] = ECRYPTFS_TAG_70_PACKET_TYPE;
rc = ecryptfs_write_packet_length(&dest[s->i],
(ECRYPTFS_SIG_SIZE
+ 1 /* Cipher code */
+ s->block_aligned_filename_size),
&s->packet_size_len);
if (rc) {
printk(KERN_ERR "%s: Error generating tag 70 packet "
"header; cannot generate packet length; rc = [%d]\n",
__func__, rc);
goto out_free_unlock;
}
s->i += s->packet_size_len;
ecryptfs_from_hex(&dest[s->i],
mount_crypt_stat->global_default_fnek_sig,
ECRYPTFS_SIG_SIZE);
s->i += ECRYPTFS_SIG_SIZE;
s->cipher_code = ecryptfs_code_for_cipher_string(
mount_crypt_stat->global_default_fn_cipher_name,
mount_crypt_stat->global_default_fn_cipher_key_bytes);
if (s->cipher_code == 0) {
printk(KERN_WARNING "%s: Unable to generate code for "
"cipher [%s] with key bytes [%zd]\n", __func__,
mount_crypt_stat->global_default_fn_cipher_name,
mount_crypt_stat->global_default_fn_cipher_key_bytes);
rc = -EINVAL;
goto out_free_unlock;
}
dest[s->i++] = s->cipher_code;
/* TODO: Support other key modules than passphrase for
* filename encryption */
if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
rc = -EOPNOTSUPP;
printk(KERN_INFO "%s: Filename encryption only supports "
"password tokens\n", __func__);
goto out_free_unlock;
}
s->hash_tfm = crypto_alloc_shash(ECRYPTFS_TAG_70_DIGEST, 0, 0);
if (IS_ERR(s->hash_tfm)) {
rc = PTR_ERR(s->hash_tfm);
printk(KERN_ERR "%s: Error attempting to "
"allocate hash crypto context; rc = [%d]\n",
__func__, rc);
goto out_free_unlock;
}
s->hash_desc = kmalloc(sizeof(*s->hash_desc) +
crypto_shash_descsize(s->hash_tfm), GFP_KERNEL);
if (!s->hash_desc) {
rc = -ENOMEM;
goto out_release_free_unlock;
}
s->hash_desc->tfm = s->hash_tfm;
s->hash_desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
rc = crypto_shash_digest(s->hash_desc,
(u8 *)s->auth_tok->token.password.session_key_encryption_key,
s->auth_tok->token.password.session_key_encryption_key_bytes,
s->hash);
if (rc) {
printk(KERN_ERR
"%s: Error computing crypto hash; rc = [%d]\n",
__func__, rc);
goto out_release_free_unlock;
}
for (s->j = 0; s->j < (s->num_rand_bytes - 1); s->j++) {
s->block_aligned_filename[s->j] =
s->hash[(s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)];
if ((s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)
== (ECRYPTFS_TAG_70_DIGEST_SIZE - 1)) {
rc = crypto_shash_digest(s->hash_desc, (u8 *)s->hash,
ECRYPTFS_TAG_70_DIGEST_SIZE,
s->tmp_hash);
if (rc) {
printk(KERN_ERR
"%s: Error computing crypto hash; "
"rc = [%d]\n", __func__, rc);
goto out_release_free_unlock;
}
memcpy(s->hash, s->tmp_hash,
ECRYPTFS_TAG_70_DIGEST_SIZE);
}
if (s->block_aligned_filename[s->j] == '\0')
s->block_aligned_filename[s->j] = ECRYPTFS_NON_NULL;
}
memcpy(&s->block_aligned_filename[s->num_rand_bytes], filename,
filename_size);
rc = virt_to_scatterlist(s->block_aligned_filename,
s->block_aligned_filename_size, s->src_sg, 2);
if (rc < 1) {
printk(KERN_ERR "%s: Internal error whilst attempting to "
"convert filename memory to scatterlist; rc = [%d]. "
"block_aligned_filename_size = [%zd]\n", __func__, rc,
s->block_aligned_filename_size);
goto out_release_free_unlock;
}
rc = virt_to_scatterlist(&dest[s->i], s->block_aligned_filename_size,
s->dst_sg, 2);
if (rc < 1) {
printk(KERN_ERR "%s: Internal error whilst attempting to "
"convert encrypted filename memory to scatterlist; "
"rc = [%d]. block_aligned_filename_size = [%zd]\n",
__func__, rc, s->block_aligned_filename_size);
goto out_release_free_unlock;
}
/* The characters in the first block effectively do the job
* of the IV here, so we just use 0's for the IV. Note the
* constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
* >= ECRYPTFS_MAX_IV_BYTES. */
rc = crypto_skcipher_setkey(
s->skcipher_tfm,
s->auth_tok->token.password.session_key_encryption_key,
mount_crypt_stat->global_default_fn_cipher_key_bytes);
if (rc < 0) {
printk(KERN_ERR "%s: Error setting key for crypto context; "
"rc = [%d]. s->auth_tok->token.password.session_key_"
"encryption_key = [0x%p]; mount_crypt_stat->"
"global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
rc,
s->auth_tok->token.password.session_key_encryption_key,
mount_crypt_stat->global_default_fn_cipher_key_bytes);
goto out_release_free_unlock;
}
skcipher_request_set_crypt(s->skcipher_req, s->src_sg, s->dst_sg,
s->block_aligned_filename_size, s->iv);
rc = crypto_skcipher_encrypt(s->skcipher_req);
if (rc) {
printk(KERN_ERR "%s: Error attempting to encrypt filename; "
"rc = [%d]\n", __func__, rc);
goto out_release_free_unlock;
}
s->i += s->block_aligned_filename_size;
(*packet_size) = s->i;
(*remaining_bytes) -= (*packet_size);
out_release_free_unlock:
crypto_free_shash(s->hash_tfm);
out_free_unlock:
kzfree(s->block_aligned_filename);
out_unlock:
mutex_unlock(s->tfm_mutex);
out:
if (auth_tok_key) {
up_write(&(auth_tok_key->sem));
key_put(auth_tok_key);
}
skcipher_request_free(s->skcipher_req);
kzfree(s->hash_desc);
kfree(s);
return rc;
}
struct ecryptfs_parse_tag_70_packet_silly_stack {
u8 cipher_code;
size_t max_packet_size;
size_t packet_size_len;
size_t parsed_tag_70_packet_size;
size_t block_aligned_filename_size;
size_t block_size;
size_t i;
struct mutex *tfm_mutex;
char *decrypted_filename;
struct ecryptfs_auth_tok *auth_tok;
struct scatterlist src_sg[2];
struct scatterlist dst_sg[2];
struct crypto_skcipher *skcipher_tfm;
struct skcipher_request *skcipher_req;
char fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX + 1];
char iv[ECRYPTFS_MAX_IV_BYTES];
char cipher_string[ECRYPTFS_MAX_CIPHER_NAME_SIZE + 1];
};
/**
* parse_tag_70_packet - Parse and process FNEK-encrypted passphrase packet
* @filename: This function kmalloc's the memory for the filename
* @filename_size: This function sets this to the amount of memory
* kmalloc'd for the filename
* @packet_size: This function sets this to the the number of octets
* in the packet parsed
* @mount_crypt_stat: The mount-wide cryptographic context
* @data: The memory location containing the start of the tag 70
* packet
* @max_packet_size: The maximum legal size of the packet to be parsed
* from @data
*
* Returns zero on success; non-zero otherwise
*/
int
ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
size_t *packet_size,
struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
char *data, size_t max_packet_size)
{
struct ecryptfs_parse_tag_70_packet_silly_stack *s;
struct key *auth_tok_key = NULL;
int rc = 0;
(*packet_size) = 0;
(*filename_size) = 0;
(*filename) = NULL;
s = kzalloc(sizeof(*s), GFP_KERNEL);
if (!s)
return -ENOMEM;
if (max_packet_size < ECRYPTFS_TAG_70_MIN_METADATA_SIZE) {
printk(KERN_WARNING "%s: max_packet_size is [%zd]; it must be "
"at least [%d]\n", __func__, max_packet_size,
ECRYPTFS_TAG_70_MIN_METADATA_SIZE);
rc = -EINVAL;
goto out;
}
/* Octet 0: Tag 70 identifier
* Octets 1-N1: Tag 70 packet size (includes cipher identifier
* and block-aligned encrypted filename size)
* Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
* Octet N2-N3: Cipher identifier (1 octet)
* Octets N3-N4: Block-aligned encrypted filename
* - Consists of a minimum number of random numbers, a \0
* separator, and then the filename */
if (data[(*packet_size)++] != ECRYPTFS_TAG_70_PACKET_TYPE) {
printk(KERN_WARNING "%s: Invalid packet tag [0x%.2x]; must be "
"tag [0x%.2x]\n", __func__,
data[((*packet_size) - 1)], ECRYPTFS_TAG_70_PACKET_TYPE);
rc = -EINVAL;
goto out;
}
rc = ecryptfs_parse_packet_length(&data[(*packet_size)],
&s->parsed_tag_70_packet_size,
&s->packet_size_len);
if (rc) {
printk(KERN_WARNING "%s: Error parsing packet length; "
"rc = [%d]\n", __func__, rc);
goto out;
}
s->block_aligned_filename_size = (s->parsed_tag_70_packet_size
- ECRYPTFS_SIG_SIZE - 1);
if ((1 + s->packet_size_len + s->parsed_tag_70_packet_size)
> max_packet_size) {
printk(KERN_WARNING "%s: max_packet_size is [%zd]; real packet "
"size is [%zd]\n", __func__, max_packet_size,
(1 + s->packet_size_len + 1
+ s->block_aligned_filename_size));
rc = -EINVAL;
goto out;
}
(*packet_size) += s->packet_size_len;
ecryptfs_to_hex(s->fnek_sig_hex, &data[(*packet_size)],
ECRYPTFS_SIG_SIZE);
s->fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX] = '\0';
(*packet_size) += ECRYPTFS_SIG_SIZE;
s->cipher_code = data[(*packet_size)++];
rc = ecryptfs_cipher_code_to_string(s->cipher_string, s->cipher_code);
if (rc) {
printk(KERN_WARNING "%s: Cipher code [%d] is invalid\n",
__func__, s->cipher_code);
goto out;
}
rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
&s->auth_tok, mount_crypt_stat,
s->fnek_sig_hex);
if (rc) {
printk(KERN_ERR "%s: Error attempting to find auth tok for "
"fnek sig [%s]; rc = [%d]\n", __func__, s->fnek_sig_hex,
rc);
goto out;
}
rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&s->skcipher_tfm,
&s->tfm_mutex,
s->cipher_string);
if (unlikely(rc)) {
printk(KERN_ERR "Internal error whilst attempting to get "
"tfm and mutex for cipher name [%s]; rc = [%d]\n",
s->cipher_string, rc);
goto out;
}
mutex_lock(s->tfm_mutex);
rc = virt_to_scatterlist(&data[(*packet_size)],
s->block_aligned_filename_size, s->src_sg, 2);
if (rc < 1) {
printk(KERN_ERR "%s: Internal error whilst attempting to "
"convert encrypted filename memory to scatterlist; "
"rc = [%d]. block_aligned_filename_size = [%zd]\n",
__func__, rc, s->block_aligned_filename_size);