-
Notifications
You must be signed in to change notification settings - Fork 127
/
Copy pathcrypto.c
2075 lines (1929 loc) · 60.3 KB
/
crypto.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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* eCryptfs: Linux filesystem encryption layer
*
* Copyright (C) 1997-2004 Erez Zadok
* Copyright (C) 2001-2004 Stony Brook University
* Copyright (C) 2004-2007 International Business Machines Corp.
* Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
* Michael C. Thompson <mcthomps@us.ibm.com>
*/
#include <crypto/hash.h>
#include <crypto/skcipher.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/pagemap.h>
#include <linux/random.h>
#include <linux/compiler.h>
#include <linux/key.h>
#include <linux/namei.h>
#include <linux/file.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/unaligned.h>
#include <linux/kernel.h>
#include <linux/xattr.h>
#include "ecryptfs_kernel.h"
#define DECRYPT 0
#define ENCRYPT 1
/**
* ecryptfs_from_hex
* @dst: Buffer to take the bytes from src hex; must be at least of
* size (src_size / 2)
* @src: Buffer to be converted from a hex string representation to raw value
* @dst_size: size of dst buffer, or number of hex characters pairs to convert
*/
void ecryptfs_from_hex(char *dst, char *src, int dst_size)
{
int x;
char tmp[3] = { 0, };
for (x = 0; x < dst_size; x++) {
tmp[0] = src[x * 2];
tmp[1] = src[x * 2 + 1];
dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
}
}
/**
* ecryptfs_calculate_md5 - calculates the md5 of @src
* @dst: Pointer to 16 bytes of allocated memory
* @crypt_stat: Pointer to crypt_stat struct for the current inode
* @src: Data to be md5'd
* @len: Length of @src
*
* Uses the allocated crypto context that crypt_stat references to
* generate the MD5 sum of the contents of src.
*/
static int ecryptfs_calculate_md5(char *dst,
struct ecryptfs_crypt_stat *crypt_stat,
char *src, int len)
{
int rc = crypto_shash_tfm_digest(crypt_stat->hash_tfm, src, len, dst);
if (rc) {
printk(KERN_ERR
"%s: Error computing crypto hash; rc = [%d]\n",
__func__, rc);
goto out;
}
out:
return rc;
}
static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
char *cipher_name,
char *chaining_modifier)
{
int cipher_name_len = strlen(cipher_name);
int chaining_modifier_len = strlen(chaining_modifier);
int algified_name_len;
int rc;
algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
(*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
if (!(*algified_name)) {
rc = -ENOMEM;
goto out;
}
snprintf((*algified_name), algified_name_len, "%s(%s)",
chaining_modifier, cipher_name);
rc = 0;
out:
return rc;
}
/**
* ecryptfs_derive_iv
* @iv: destination for the derived iv vale
* @crypt_stat: Pointer to crypt_stat struct for the current inode
* @offset: Offset of the extent whose IV we are to derive
*
* Generate the initialization vector from the given root IV and page
* offset.
*
* Returns zero on success; non-zero on error.
*/
int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
loff_t offset)
{
int rc = 0;
char dst[MD5_DIGEST_SIZE];
char src[ECRYPTFS_MAX_IV_BYTES + 16];
if (unlikely(ecryptfs_verbosity > 0)) {
ecryptfs_printk(KERN_DEBUG, "root iv:\n");
ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
}
/* TODO: It is probably secure to just cast the least
* significant bits of the root IV into an unsigned long and
* add the offset to that rather than go through all this
* hashing business. -Halcrow */
memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
memset((src + crypt_stat->iv_bytes), 0, 16);
snprintf((src + crypt_stat->iv_bytes), 16, "%lld", offset);
if (unlikely(ecryptfs_verbosity > 0)) {
ecryptfs_printk(KERN_DEBUG, "source:\n");
ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
}
rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
(crypt_stat->iv_bytes + 16));
if (rc) {
ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
"MD5 while generating IV for a page\n");
goto out;
}
memcpy(iv, dst, crypt_stat->iv_bytes);
if (unlikely(ecryptfs_verbosity > 0)) {
ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
}
out:
return rc;
}
/**
* ecryptfs_init_crypt_stat
* @crypt_stat: Pointer to the crypt_stat struct to initialize.
*
* Initialize the crypt_stat structure.
*/
int ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
{
struct crypto_shash *tfm;
int rc;
tfm = crypto_alloc_shash(ECRYPTFS_DEFAULT_HASH, 0, 0);
if (IS_ERR(tfm)) {
rc = PTR_ERR(tfm);
ecryptfs_printk(KERN_ERR, "Error attempting to "
"allocate crypto context; rc = [%d]\n",
rc);
return rc;
}
memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
INIT_LIST_HEAD(&crypt_stat->keysig_list);
mutex_init(&crypt_stat->keysig_list_mutex);
mutex_init(&crypt_stat->cs_mutex);
mutex_init(&crypt_stat->cs_tfm_mutex);
crypt_stat->hash_tfm = tfm;
crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
return 0;
}
/**
* ecryptfs_destroy_crypt_stat
* @crypt_stat: Pointer to the crypt_stat struct to initialize.
*
* Releases all memory associated with a crypt_stat struct.
*/
void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
{
struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
crypto_free_skcipher(crypt_stat->tfm);
crypto_free_shash(crypt_stat->hash_tfm);
list_for_each_entry_safe(key_sig, key_sig_tmp,
&crypt_stat->keysig_list, crypt_stat_list) {
list_del(&key_sig->crypt_stat_list);
kmem_cache_free(ecryptfs_key_sig_cache, key_sig);
}
memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
}
void ecryptfs_destroy_mount_crypt_stat(
struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
{
struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
return;
mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
list_for_each_entry_safe(auth_tok, auth_tok_tmp,
&mount_crypt_stat->global_auth_tok_list,
mount_crypt_stat_list) {
list_del(&auth_tok->mount_crypt_stat_list);
if (!(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
key_put(auth_tok->global_auth_tok_key);
kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
}
mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
}
/**
* virt_to_scatterlist
* @addr: Virtual address
* @size: Size of data; should be an even multiple of the block size
* @sg: Pointer to scatterlist array; set to NULL to obtain only
* the number of scatterlist structs required in array
* @sg_size: Max array size
*
* Fills in a scatterlist array with page references for a passed
* virtual address.
*
* Returns the number of scatterlist structs in array used
*/
int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
int sg_size)
{
int i = 0;
struct page *pg;
int offset;
int remainder_of_page;
sg_init_table(sg, sg_size);
while (size > 0 && i < sg_size) {
pg = virt_to_page(addr);
offset = offset_in_page(addr);
sg_set_page(&sg[i], pg, 0, offset);
remainder_of_page = PAGE_SIZE - offset;
if (size >= remainder_of_page) {
sg[i].length = remainder_of_page;
addr += remainder_of_page;
size -= remainder_of_page;
} else {
sg[i].length = size;
addr += size;
size = 0;
}
i++;
}
if (size > 0)
return -ENOMEM;
return i;
}
/**
* crypt_scatterlist
* @crypt_stat: Pointer to the crypt_stat struct to initialize.
* @dst_sg: Destination of the data after performing the crypto operation
* @src_sg: Data to be encrypted or decrypted
* @size: Length of data
* @iv: IV to use
* @op: ENCRYPT or DECRYPT to indicate the desired operation
*
* Returns the number of bytes encrypted or decrypted; negative value on error
*/
static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
struct scatterlist *dst_sg,
struct scatterlist *src_sg, int size,
unsigned char *iv, int op)
{
struct skcipher_request *req = NULL;
DECLARE_CRYPTO_WAIT(ecr);
int rc = 0;
if (unlikely(ecryptfs_verbosity > 0)) {
ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
crypt_stat->key_size);
ecryptfs_dump_hex(crypt_stat->key,
crypt_stat->key_size);
}
mutex_lock(&crypt_stat->cs_tfm_mutex);
req = skcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
if (!req) {
mutex_unlock(&crypt_stat->cs_tfm_mutex);
rc = -ENOMEM;
goto out;
}
skcipher_request_set_callback(req,
CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
crypto_req_done, &ecr);
/* Consider doing this once, when the file is opened */
if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
rc = crypto_skcipher_setkey(crypt_stat->tfm, crypt_stat->key,
crypt_stat->key_size);
if (rc) {
ecryptfs_printk(KERN_ERR,
"Error setting key; rc = [%d]\n",
rc);
mutex_unlock(&crypt_stat->cs_tfm_mutex);
rc = -EINVAL;
goto out;
}
crypt_stat->flags |= ECRYPTFS_KEY_SET;
}
mutex_unlock(&crypt_stat->cs_tfm_mutex);
skcipher_request_set_crypt(req, src_sg, dst_sg, size, iv);
rc = op == ENCRYPT ? crypto_skcipher_encrypt(req) :
crypto_skcipher_decrypt(req);
rc = crypto_wait_req(rc, &ecr);
out:
skcipher_request_free(req);
return rc;
}
/*
* lower_offset_for_page
*
* Convert an eCryptfs page index into a lower byte offset
*/
static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
struct folio *folio)
{
return ecryptfs_lower_header_size(crypt_stat) +
(loff_t)folio->index * PAGE_SIZE;
}
/**
* crypt_extent
* @crypt_stat: crypt_stat containing cryptographic context for the
* encryption operation
* @dst_page: The page to write the result into
* @src_page: The page to read from
* @page_index: The offset in the file (in units of PAGE_SIZE)
* @extent_offset: Page extent offset for use in generating IV
* @op: ENCRYPT or DECRYPT to indicate the desired operation
*
* Encrypts or decrypts one extent of data.
*
* Return zero on success; non-zero otherwise
*/
static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
struct page *dst_page,
struct page *src_page,
pgoff_t page_index,
unsigned long extent_offset, int op)
{
loff_t extent_base;
char extent_iv[ECRYPTFS_MAX_IV_BYTES];
struct scatterlist src_sg, dst_sg;
size_t extent_size = crypt_stat->extent_size;
int rc;
extent_base = (((loff_t)page_index) * (PAGE_SIZE / extent_size));
rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
(extent_base + extent_offset));
if (rc) {
ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
"extent [0x%.16llx]; rc = [%d]\n",
(unsigned long long)(extent_base + extent_offset), rc);
goto out;
}
sg_init_table(&src_sg, 1);
sg_init_table(&dst_sg, 1);
sg_set_page(&src_sg, src_page, extent_size,
extent_offset * extent_size);
sg_set_page(&dst_sg, dst_page, extent_size,
extent_offset * extent_size);
rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size,
extent_iv, op);
if (rc < 0) {
printk(KERN_ERR "%s: Error attempting to crypt page with "
"page_index = [%ld], extent_offset = [%ld]; "
"rc = [%d]\n", __func__, page_index, extent_offset, rc);
goto out;
}
rc = 0;
out:
return rc;
}
/**
* ecryptfs_encrypt_page
* @folio: Folio mapped from the eCryptfs inode for the file; contains
* decrypted content that needs to be encrypted (to a temporary
* page; not in place) and written out to the lower file
*
* Encrypt an eCryptfs page. This is done on a per-extent basis. Note
* that eCryptfs pages may straddle the lower pages -- for instance,
* if the file was created on a machine with an 8K page size
* (resulting in an 8K header), and then the file is copied onto a
* host with a 32K page size, then when reading page 0 of the eCryptfs
* file, 24K of page 0 of the lower file will be read and decrypted,
* and then 8K of page 1 of the lower file will be read and decrypted.
*
* Returns zero on success; negative on error
*/
int ecryptfs_encrypt_page(struct folio *folio)
{
struct inode *ecryptfs_inode;
struct ecryptfs_crypt_stat *crypt_stat;
char *enc_extent_virt;
struct page *enc_extent_page = NULL;
loff_t extent_offset;
loff_t lower_offset;
int rc = 0;
ecryptfs_inode = folio->mapping->host;
crypt_stat =
&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
enc_extent_page = alloc_page(GFP_USER);
if (!enc_extent_page) {
rc = -ENOMEM;
ecryptfs_printk(KERN_ERR, "Error allocating memory for "
"encrypted extent\n");
goto out;
}
for (extent_offset = 0;
extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
extent_offset++) {
rc = crypt_extent(crypt_stat, enc_extent_page,
folio_page(folio, 0), folio->index,
extent_offset, ENCRYPT);
if (rc) {
printk(KERN_ERR "%s: Error encrypting extent; "
"rc = [%d]\n", __func__, rc);
goto out;
}
}
lower_offset = lower_offset_for_page(crypt_stat, folio);
enc_extent_virt = kmap_local_page(enc_extent_page);
rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
PAGE_SIZE);
kunmap_local(enc_extent_virt);
if (rc < 0) {
ecryptfs_printk(KERN_ERR,
"Error attempting to write lower page; rc = [%d]\n",
rc);
goto out;
}
rc = 0;
out:
if (enc_extent_page) {
__free_page(enc_extent_page);
}
return rc;
}
/**
* ecryptfs_decrypt_page
* @folio: Folio mapped from the eCryptfs inode for the file; data read
* and decrypted from the lower file will be written into this
* page
*
* Decrypt an eCryptfs page. This is done on a per-extent basis. Note
* that eCryptfs pages may straddle the lower pages -- for instance,
* if the file was created on a machine with an 8K page size
* (resulting in an 8K header), and then the file is copied onto a
* host with a 32K page size, then when reading page 0 of the eCryptfs
* file, 24K of page 0 of the lower file will be read and decrypted,
* and then 8K of page 1 of the lower file will be read and decrypted.
*
* Returns zero on success; negative on error
*/
int ecryptfs_decrypt_page(struct folio *folio)
{
struct inode *ecryptfs_inode;
struct ecryptfs_crypt_stat *crypt_stat;
char *page_virt;
unsigned long extent_offset;
loff_t lower_offset;
int rc = 0;
ecryptfs_inode = folio->mapping->host;
crypt_stat =
&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
lower_offset = lower_offset_for_page(crypt_stat, folio);
page_virt = kmap_local_folio(folio, 0);
rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_SIZE,
ecryptfs_inode);
kunmap_local(page_virt);
if (rc < 0) {
ecryptfs_printk(KERN_ERR,
"Error attempting to read lower page; rc = [%d]\n",
rc);
goto out;
}
for (extent_offset = 0;
extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
extent_offset++) {
struct page *page = folio_page(folio, 0);
rc = crypt_extent(crypt_stat, page, page, folio->index,
extent_offset, DECRYPT);
if (rc) {
printk(KERN_ERR "%s: Error decrypting extent; "
"rc = [%d]\n", __func__, rc);
goto out;
}
}
out:
return rc;
}
#define ECRYPTFS_MAX_SCATTERLIST_LEN 4
/**
* ecryptfs_init_crypt_ctx
* @crypt_stat: Uninitialized crypt stats structure
*
* Initialize the crypto context.
*
* TODO: Performance: Keep a cache of initialized cipher contexts;
* only init if needed
*/
int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
{
char *full_alg_name;
int rc = -EINVAL;
ecryptfs_printk(KERN_DEBUG,
"Initializing cipher [%s]; strlen = [%d]; "
"key_size_bits = [%zd]\n",
crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
crypt_stat->key_size << 3);
mutex_lock(&crypt_stat->cs_tfm_mutex);
if (crypt_stat->tfm) {
rc = 0;
goto out_unlock;
}
rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
crypt_stat->cipher, "cbc");
if (rc)
goto out_unlock;
crypt_stat->tfm = crypto_alloc_skcipher(full_alg_name, 0, 0);
if (IS_ERR(crypt_stat->tfm)) {
rc = PTR_ERR(crypt_stat->tfm);
crypt_stat->tfm = NULL;
ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
"Error initializing cipher [%s]\n",
full_alg_name);
goto out_free;
}
crypto_skcipher_set_flags(crypt_stat->tfm,
CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
rc = 0;
out_free:
kfree(full_alg_name);
out_unlock:
mutex_unlock(&crypt_stat->cs_tfm_mutex);
return rc;
}
static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
{
int extent_size_tmp;
crypt_stat->extent_mask = 0xFFFFFFFF;
crypt_stat->extent_shift = 0;
if (crypt_stat->extent_size == 0)
return;
extent_size_tmp = crypt_stat->extent_size;
while ((extent_size_tmp & 0x01) == 0) {
extent_size_tmp >>= 1;
crypt_stat->extent_mask <<= 1;
crypt_stat->extent_shift++;
}
}
void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
{
/* Default values; may be overwritten as we are parsing the
* packets. */
crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
set_extent_mask_and_shift(crypt_stat);
crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
else {
if (PAGE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
crypt_stat->metadata_size =
ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
else
crypt_stat->metadata_size = PAGE_SIZE;
}
}
/*
* ecryptfs_compute_root_iv
*
* On error, sets the root IV to all 0's.
*/
int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
{
int rc = 0;
char dst[MD5_DIGEST_SIZE];
BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
BUG_ON(crypt_stat->iv_bytes <= 0);
if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
rc = -EINVAL;
ecryptfs_printk(KERN_WARNING, "Session key not valid; "
"cannot generate root IV\n");
goto out;
}
rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
crypt_stat->key_size);
if (rc) {
ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
"MD5 while generating root IV\n");
goto out;
}
memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
out:
if (rc) {
memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
}
return rc;
}
static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
{
get_random_bytes(crypt_stat->key, crypt_stat->key_size);
crypt_stat->flags |= ECRYPTFS_KEY_VALID;
ecryptfs_compute_root_iv(crypt_stat);
if (unlikely(ecryptfs_verbosity > 0)) {
ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
ecryptfs_dump_hex(crypt_stat->key,
crypt_stat->key_size);
}
}
/**
* ecryptfs_copy_mount_wide_flags_to_inode_flags
* @crypt_stat: The inode's cryptographic context
* @mount_crypt_stat: The mount point's cryptographic context
*
* This function propagates the mount-wide flags to individual inode
* flags.
*/
static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
struct ecryptfs_crypt_stat *crypt_stat,
struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
{
if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
if (mount_crypt_stat->flags
& ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
else if (mount_crypt_stat->flags
& ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
}
}
static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
struct ecryptfs_crypt_stat *crypt_stat,
struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
{
struct ecryptfs_global_auth_tok *global_auth_tok;
int rc = 0;
mutex_lock(&crypt_stat->keysig_list_mutex);
mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
list_for_each_entry(global_auth_tok,
&mount_crypt_stat->global_auth_tok_list,
mount_crypt_stat_list) {
if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
continue;
rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
if (rc) {
printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
goto out;
}
}
out:
mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
mutex_unlock(&crypt_stat->keysig_list_mutex);
return rc;
}
/**
* ecryptfs_set_default_crypt_stat_vals
* @crypt_stat: The inode's cryptographic context
* @mount_crypt_stat: The mount point's cryptographic context
*
* Default values in the event that policy does not override them.
*/
static void ecryptfs_set_default_crypt_stat_vals(
struct ecryptfs_crypt_stat *crypt_stat,
struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
{
ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
mount_crypt_stat);
ecryptfs_set_default_sizes(crypt_stat);
strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
crypt_stat->mount_crypt_stat = mount_crypt_stat;
}
/**
* ecryptfs_new_file_context
* @ecryptfs_inode: The eCryptfs inode
*
* If the crypto context for the file has not yet been established,
* this is where we do that. Establishing a new crypto context
* involves the following decisions:
* - What cipher to use?
* - What set of authentication tokens to use?
* Here we just worry about getting enough information into the
* authentication tokens so that we know that they are available.
* We associate the available authentication tokens with the new file
* via the set of signatures in the crypt_stat struct. Later, when
* the headers are actually written out, we may again defer to
* userspace to perform the encryption of the session key; for the
* foreseeable future, this will be the case with public key packets.
*
* Returns zero on success; non-zero otherwise
*/
int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
{
struct ecryptfs_crypt_stat *crypt_stat =
&ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
&ecryptfs_superblock_to_private(
ecryptfs_inode->i_sb)->mount_crypt_stat;
int cipher_name_len;
int rc = 0;
ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
mount_crypt_stat);
rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
mount_crypt_stat);
if (rc) {
printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
"to the inode key sigs; rc = [%d]\n", rc);
goto out;
}
cipher_name_len =
strlen(mount_crypt_stat->global_default_cipher_name);
memcpy(crypt_stat->cipher,
mount_crypt_stat->global_default_cipher_name,
cipher_name_len);
crypt_stat->cipher[cipher_name_len] = '\0';
crypt_stat->key_size =
mount_crypt_stat->global_default_cipher_key_size;
ecryptfs_generate_new_key(crypt_stat);
rc = ecryptfs_init_crypt_ctx(crypt_stat);
if (rc)
ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
"context for cipher [%s]: rc = [%d]\n",
crypt_stat->cipher, rc);
out:
return rc;
}
/**
* ecryptfs_validate_marker - check for the ecryptfs marker
* @data: The data block in which to check
*
* Returns zero if marker found; -EINVAL if not found
*/
static int ecryptfs_validate_marker(char *data)
{
u32 m_1, m_2;
m_1 = get_unaligned_be32(data);
m_2 = get_unaligned_be32(data + 4);
if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
return 0;
ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
"MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
MAGIC_ECRYPTFS_MARKER);
ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
"[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
return -EINVAL;
}
struct ecryptfs_flag_map_elem {
u32 file_flag;
u32 local_flag;
};
/* Add support for additional flags by adding elements here. */
static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
{0x00000001, ECRYPTFS_ENABLE_HMAC},
{0x00000002, ECRYPTFS_ENCRYPTED},
{0x00000004, ECRYPTFS_METADATA_IN_XATTR},
{0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
};
/**
* ecryptfs_process_flags
* @crypt_stat: The cryptographic context
* @page_virt: Source data to be parsed
* @bytes_read: Updated with the number of bytes read
*/
static void ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
char *page_virt, int *bytes_read)
{
int i;
u32 flags;
flags = get_unaligned_be32(page_virt);
for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
if (flags & ecryptfs_flag_map[i].file_flag) {
crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
} else
crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
/* Version is in top 8 bits of the 32-bit flag vector */
crypt_stat->file_version = ((flags >> 24) & 0xFF);
(*bytes_read) = 4;
}
/**
* write_ecryptfs_marker
* @page_virt: The pointer to in a page to begin writing the marker
* @written: Number of bytes written
*
* Marker = 0x3c81b7f5
*/
static void write_ecryptfs_marker(char *page_virt, size_t *written)
{
u32 m_1, m_2;
get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
put_unaligned_be32(m_1, page_virt);
page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
put_unaligned_be32(m_2, page_virt);
(*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
}
void ecryptfs_write_crypt_stat_flags(char *page_virt,
struct ecryptfs_crypt_stat *crypt_stat,
size_t *written)
{
u32 flags = 0;
int i;
for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
flags |= ecryptfs_flag_map[i].file_flag;
/* Version is in top 8 bits of the 32-bit flag vector */
flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
put_unaligned_be32(flags, page_virt);
(*written) = 4;
}
struct ecryptfs_cipher_code_str_map_elem {
char cipher_str[16];
u8 cipher_code;
};
/* Add support for additional ciphers by adding elements here. The
* cipher_code is whatever OpenPGP applications use to identify the
* ciphers. List in order of probability. */
static struct ecryptfs_cipher_code_str_map_elem
ecryptfs_cipher_code_str_map[] = {
{"aes",RFC2440_CIPHER_AES_128 },
{"blowfish", RFC2440_CIPHER_BLOWFISH},
{"des3_ede", RFC2440_CIPHER_DES3_EDE},
{"cast5", RFC2440_CIPHER_CAST_5},
{"twofish", RFC2440_CIPHER_TWOFISH},
{"cast6", RFC2440_CIPHER_CAST_6},
{"aes", RFC2440_CIPHER_AES_192},
{"aes", RFC2440_CIPHER_AES_256}
};
/**
* ecryptfs_code_for_cipher_string
* @cipher_name: The string alias for the cipher
* @key_bytes: Length of key in bytes; used for AES code selection
*
* Returns zero on no match, or the cipher code on match
*/
u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
{
int i;
u8 code = 0;
struct ecryptfs_cipher_code_str_map_elem *map =
ecryptfs_cipher_code_str_map;
if (strcmp(cipher_name, "aes") == 0) {
switch (key_bytes) {
case 16:
code = RFC2440_CIPHER_AES_128;
break;
case 24:
code = RFC2440_CIPHER_AES_192;
break;
case 32:
code = RFC2440_CIPHER_AES_256;
}
} else {
for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
if (strcmp(cipher_name, map[i].cipher_str) == 0) {
code = map[i].cipher_code;
break;
}
}
return code;
}
/**
* ecryptfs_cipher_code_to_string
* @str: Destination to write out the cipher name
* @cipher_code: The code to convert to cipher name string
*
* Returns zero on success
*/
int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
{
int rc = 0;
int i;
str[0] = '\0';
for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
if (str[0] == '\0') {
ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
"[%d]\n", cipher_code);
rc = -EINVAL;
}
return rc;
}
int ecryptfs_read_and_validate_header_region(struct inode *inode)
{
u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
int rc;
rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
inode);
if (rc < 0)
return rc;
else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
return -EINVAL;
rc = ecryptfs_validate_marker(marker);
if (!rc)
ecryptfs_i_size_init(file_size, inode);
return rc;
}
void
ecryptfs_write_header_metadata(char *virt,
struct ecryptfs_crypt_stat *crypt_stat,
size_t *written)
{
u32 header_extent_size;
u16 num_header_extents_at_front;
header_extent_size = (u32)crypt_stat->extent_size;
num_header_extents_at_front =
(u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
put_unaligned_be32(header_extent_size, virt);
virt += 4;
put_unaligned_be16(num_header_extents_at_front, virt);
(*written) = 6;
}
struct kmem_cache *ecryptfs_header_cache;
/**
* ecryptfs_write_headers_virt
* @page_virt: The virtual address to write the headers to
* @max: The size of memory allocated at page_virt
* @size: Set to the number of bytes written by this function
* @crypt_stat: The cryptographic context
* @ecryptfs_dentry: The eCryptfs dentry