aboutsummaryrefslogtreecommitdiff
path: root/fs/ecryptfs/keystore.c
blob: f7debe6961d10058a608245bc46ee8fed99003cd (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
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
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
/**
 * 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 <mhalcrow@us.ibm.com>
 *              Michael C. Thompson <mcthomps@us.ibm.com>
 *              Trevor S. Highland <trevor.highland@gmail.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; 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 <linux/string.h>
#include <linux/syscalls.h>
#include <linux/pagemap.h>
#include <linux/key.h>
#include <linux/random.h>
#include <linux/crypto.h>
#include <linux/scatterlist.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.
 */
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%.16x]\n", err_code);
		rc = -EINVAL;
	}
	return rc;
}

/**
 * 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
 */
static int 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) = (unsigned char)data[0];
		(*length_size) = 1;
	} else if (data[0] < 224) {
		/* Two-byte length */
		(*size) = (((unsigned char)(data[0]) - 192) * 256);
		(*size) += ((unsigned char)(data[1]) + 192);
		(*length_size) = 2;
	} else if (data[0] == 255) {
		/* Five-byte length; we're not supposed to see this */
		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;
}

/**
 * write_packet_length
 * @dest: The byte array target into which to write the
 *       length. Must have at least 5 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.
 */
static int 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 {
		rc = -EINVAL;
		ecryptfs_printk(KERN_WARNING,
				"Unsupported packet size: [%d]\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 = 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 = 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, u16 *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 = 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 received netlink message 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, size_t 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 = 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 = 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;
		goto out;
	}
	if (data[i++] != ECRYPTFS_TAG_67_PACKET_TYPE) {
		ecryptfs_printk(KERN_ERR, "Type should be ECRYPTFS_TAG_67\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 = 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)) {
		ecryptfs_printk(KERN_ERR, "message_len [%d]; max len is [%d]\n",
				message_len, (i + key_rec->enc_key_size));
		rc = -EIO;
		goto out;
	}
	if (key_rec->enc_key_size > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
		ecryptfs_printk(KERN_ERR, "Encrypted key_size [%d] larger than "
				"the maximum key size [%d]\n",
				key_rec->enc_key_size,
				ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
		rc = -EIO;
		goto out;
	}
	memcpy(key_rec->enc_key, &data[i], key_rec->enc_key_size);
out:
	return rc;
}

/**
 * decrypt_pki_encrypted_session_key - Decrypt the session key with
 * the given auth_tok.
 *
 * Returns Zero on success; non-zero error otherwise.
 */
static int
decrypt_pki_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
				  struct ecryptfs_crypt_stat *crypt_stat)
{
	u16 cipher_code = 0;
	struct ecryptfs_msg_ctx *msg_ctx;
	struct ecryptfs_message *msg = NULL;
	char *auth_tok_sig;
	char *netlink_message;
	size_t netlink_message_length;
	int rc;

	if ((rc = ecryptfs_get_auth_tok_sig(&auth_tok_sig, auth_tok))) {
		printk(KERN_ERR "Unrecognized auth tok type: [%d]\n",
		       auth_tok->token_type);
		goto out;
	}
	rc = write_tag_64_packet(auth_tok_sig, &(auth_tok->session_key),
				 &netlink_message, &netlink_message_length);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Failed to write tag 64 packet");
		goto out;
	}
	rc = ecryptfs_send_message(ecryptfs_transport, netlink_message,
				   netlink_message_length, &msg_ctx);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error sending netlink message\n");
		goto out;
	}
	rc = ecryptfs_wait_for_response(msg_ctx, &msg);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Failed to receive tag 65 packet "
				"from the user space daemon\n");
		rc = -EIO;
		goto out;
	}
	rc = parse_tag_65_packet(&(auth_tok->session_key),
				 &cipher_code, msg);
	if (rc) {
		printk(KERN_ERR "Failed to parse tag 65 packet; rc = [%d]\n",
		       rc);
		goto out;
	}
	auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
	memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
	       auth_tok->session_key.decrypted_key_size);
	crypt_stat->key_size = auth_tok->session_key.decrypted_key_size;
	rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher, cipher_code);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Cipher code [%d] is invalid\n",
				cipher_code)
		goto out;
	}
	crypt_stat->flags |= ECRYPTFS_KEY_VALID;
	if (ecryptfs_verbosity > 0) {
		ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
		ecryptfs_dump_hex(crypt_stat->key,
				  crypt_stat->key_size);
	}
out:
	if (msg)
		kfree(msg);
	return rc;
}

static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
{
	struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
	struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;

	list_for_each_entry_safe(auth_tok_list_item, auth_tok_list_item_tmp,
				 auth_tok_list_head, list) {
		list_del(&auth_tok_list_item->list);
		kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
				auth_tok_list_item);
	}
}

struct kmem_cache *ecryptfs_auth_tok_list_item_cache;

/**
 * parse_tag_1_packet
 * @crypt_stat: The cryptographic context to modify based on packet
 *              contents.
 * @data: The raw bytes of the packet.
 * @auth_tok_list: eCryptfs parses packets into authentication tokens;
 *                 a new authentication token will be placed at the end
 *                 of this list for this packet.
 * @new_auth_tok: Pointer to a pointer to memory that this function
 *                allocates; sets the memory address of the pointer to
 *                NULL on error. This object is added to the
 *                auth_tok_list.
 * @packet_size: This function writes the size of the parsed packet
 *               into this memory location; zero on error.
 *
 * Returns zero on success; non-zero on error.
 */
static int
parse_tag_1_packet(struct ecryptfs_crypt_stat *crypt_stat,
		   unsigned char *data, struct list_head *auth_tok_list,
		   struct ecryptfs_auth_tok **new_auth_tok,
		   size_t *packet_size, size_t max_packet_size)
{
	size_t body_size;
	struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
	size_t length_size;
	int rc = 0;

	(*packet_size) = 0;
	(*new_auth_tok) = NULL;
	/**
	 * This format is inspired by OpenPGP; see RFC 2440
	 * packet tag 1
	 *
	 * Tag 1 identifier (1 byte)
	 * Max Tag 1 packet size (max 3 bytes)
	 * Version (1 byte)
	 * Key identifier (8 bytes; ECRYPTFS_SIG_SIZE)
	 * Cipher identifier (1 byte)
	 * Encrypted key size (arbitrary)
	 *
	 * 12 bytes minimum packet size
	 */
	if (unlikely(max_packet_size < 12)) {
		printk(KERN_ERR "Invalid max packet size; must be >=12\n");
		rc = -EINVAL;
		goto out;
	}
	if (data[(*packet_size)++] != ECRYPTFS_TAG_1_PACKET_TYPE) {
		printk(KERN_ERR "Enter w/ first byte != 0x%.2x\n",
		       ECRYPTFS_TAG_1_PACKET_TYPE);
		rc = -EINVAL;
		goto out;
	}
	/* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
	 * at end of function upon failure */
	auth_tok_list_item =
		kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache,
				  GFP_KERNEL);
	if (!auth_tok_list_item) {
		printk(KERN_ERR "Unable to allocate memory\n");
		rc = -ENOMEM;
		goto out;
	}
	(*new_auth_tok) = &auth_tok_list_item->auth_tok;
	if ((rc = parse_packet_length(&data[(*packet_size)], &body_size,
				      &length_size))) {
		printk(KERN_WARNING "Error parsing packet length; "
		       "rc = [%d]\n", rc);
		goto out_free;
	}
	if (unlikely(body_size < (ECRYPTFS_SIG_SIZE + 2))) {
		printk(KERN_WARNING "Invalid body size ([%d])\n", body_size);
		rc = -EINVAL;
		goto out_free;
	}
	(*packet_size) += length_size;
	if (unlikely((*packet_size) + body_size > max_packet_size)) {
		printk(KERN_WARNING "Packet size exceeds max\n");
		rc = -EINVAL;
		goto out_free;
	}
	if (unlikely(data[(*packet_size)++] != 0x03)) {
		printk(KERN_WARNING "Unknown version number [%d]\n",
		       data[(*packet_size) - 1]);
		rc = -EINVAL;
		goto out_free;
	}
	ecryptfs_to_hex((*new_auth_tok)->token.private_key.signature,
			&data[(*packet_size)], ECRYPTFS_SIG_SIZE);
	*packet_size += ECRYPTFS_SIG_SIZE;
	/* This byte is skipped because the kernel does not need to
	 * know which public key encryption algorithm was used */
	(*packet_size)++;
	(*new_auth_tok)->session_key.encrypted_key_size =
		body_size - (ECRYPTFS_SIG_SIZE + 2);
	if ((*new_auth_tok)->session_key.encrypted_key_size
	    > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
		printk(KERN_WARNING "Tag 1 packet contains key larger "
		       "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES");
		rc = -EINVAL;
		goto out;
	}
	memcpy((*new_auth_tok)->session_key.encrypted_key,
	       &data[(*packet_size)], (body_size - (ECRYPTFS_SIG_SIZE + 2)));
	(*packet_size) += (*new_auth_tok)->session_key.encrypted_key_size;
	(*new_auth_tok)->session_key.flags &=
		~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
	(*new_auth_tok)->session_key.flags |=
		ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
	(*new_auth_tok)->token_type = ECRYPTFS_PRIVATE_KEY;
	(*new_auth_tok)->flags = 0;
	(*new_auth_tok)->session_key.flags &=
		~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
	(*new_auth_tok)->session_key.flags &=
		~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
	list_add(&auth_tok_list_item->list, auth_tok_list);
	goto out;
out_free:
	(*new_auth_tok) = NULL;
	memset(auth_tok_list_item, 0,
	       sizeof(struct ecryptfs_auth_tok_list_item));
	kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
			auth_tok_list_item);
out:
	if (rc)
		(*packet_size) = 0;
	return rc;
}

/**
 * parse_tag_3_packet
 * @crypt_stat: The cryptographic context to modify based on packet
 *              contents.
 * @data: The raw bytes of the packet.
 * @auth_tok_list: eCryptfs parses packets into authentication tokens;
 *                 a new authentication token will be placed at the end
 *                 of this list for this packet.
 * @new_auth_tok: Pointer to a pointer to memory that this function
 *                allocates; sets the memory address of the pointer to
 *                NULL on error. This object is added to the
 *                auth_tok_list.
 * @packet_size: This function writes the size of the parsed packet
 *               into this memory location; zero on error.
 * @max_packet_size: maximum number of bytes to parse
 *
 * Returns zero on success; non-zero on error.
 */
static int
parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
		   unsigned char *data, struct list_head *auth_tok_list,
		   struct ecryptfs_auth_tok **new_auth_tok,
		   size_t *packet_size, size_t max_packet_size)
{
	size_t body_size;
	struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
	size_t length_size;
	int rc = 0;

	(*packet_size) = 0;
	(*new_auth_tok) = NULL;

	/* we check that:
	 *   one byte for the Tag 3 ID flag
	 *   two bytes for the body size
	 * do not exceed the maximum_packet_size
	 */
	if (unlikely((*packet_size) + 3 > max_packet_size)) {
		ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
		rc = -EINVAL;
		goto out;
	}

	/* check for Tag 3 identifyer - one byte */
	if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
		ecryptfs_printk(KERN_ERR, "Enter w/ first byte != 0x%.2x\n",
				ECRYPTFS_TAG_3_PACKET_TYPE);
		rc = -EINVAL;
		goto out;
	}
	/* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
	 * at end of function upon failure */
	auth_tok_list_item =
	    kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache, GFP_KERNEL);
	if (!auth_tok_list_item) {
		ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
		rc = -ENOMEM;
		goto out;
	}
	(*new_auth_tok) = &auth_tok_list_item->auth_tok;

	/* check for body size - one to two bytes */
	rc = parse_packet_length(&data[(*packet_size)], &body_size,
				 &length_size);
	if (rc) {
		ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
				"rc = [%d]\n", rc);
		goto out_free;
	}
	if (unlikely(body_size < (0x05 + ECRYPTFS_SALT_SIZE))) {
		ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n",
				body_size);
		rc = -EINVAL;
		goto out_free;
	}
	(*packet_size) += length_size;

	/* now we know the length of the remainting Tag 3 packet size:
	 *   5 fix bytes for: version string, cipher, S2K ID, hash algo,
	 *                    number of hash iterations
	 *   ECRYPTFS_SALT_SIZE bytes for salt
	 *   body_size bytes minus the stuff above is the encrypted key size
	 */
	if (unlikely((*packet_size) + body_size > max_packet_size)) {
		ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
		rc = -EINVAL;
		goto out_free;
	}

	/* There are 5 characters of additional information in the
	 * packet */
	(*new_auth_tok)->session_key.encrypted_key_size =
		body_size - (0x05 + ECRYPTFS_SALT_SIZE);
	ecryptfs_printk(KERN_DEBUG, "Encrypted key size = [%d]\n",
			(*new_auth_tok)->session_key.encrypted_key_size);

	/* Version 4 (from RFC2440) - one byte */
	if (unlikely(data[(*packet_size)++] != 0x04)) {
		ecryptfs_printk(KERN_DEBUG, "Unknown version number "
				"[%d]\n", data[(*packet_size) - 1]);
		rc = -EINVAL;
		goto out_free;
	}

	/* cipher - one byte */
	ecryptfs_cipher_code_to_string(crypt_stat->cipher,
				       (u16)data[(*packet_size)]);
	/* A little extra work to differentiate among the AES key
	 * sizes; see RFC2440 */
	switch(data[(*packet_size)++]) {
	case RFC2440_CIPHER_AES_192:
		crypt_stat->key_size = 24;
		break;
	default:
		crypt_stat->key_size =
			(*new_auth_tok)->session_key.encrypted_key_size;
	}
	ecryptfs_init_crypt_ctx(crypt_stat);
	/* S2K identifier 3 (from RFC2440) */
	if (unlikely(data[(*packet_size)++] != 0x03)) {
		ecryptfs_printk(KERN_ERR, "Only S2K ID 3 is currently "
				"supported\n");
		rc = -ENOSYS;
		goto out_free;
	}

	/* TODO: finish the hash mapping */
	/* hash algorithm - one byte */
	switch (data[(*packet_size)++]) {
	case 0x01: /* See RFC2440 for these numbers and their mappings */
		/* Choose MD5 */
		/* salt - ECRYPTFS_SALT_SIZE bytes */
		memcpy((*new_auth_tok)->token.password.salt,
		       &data[(*packet_size)], ECRYPTFS_SALT_SIZE);
		(*packet_size) += ECRYPTFS_SALT_SIZE;

		/* This conversion was taken straight from RFC2440 */
		/* number of hash iterations - one byte */
		(*new_auth_tok)->token.password.hash_iterations =
			((u32) 16 + (data[(*packet_size)] & 15))
				<< ((data[(*packet_size)] >> 4) + 6);
		(*packet_size)++;

		/* encrypted session key -
		 *   (body_size-5-ECRYPTFS_SALT_SIZE) bytes */
		memcpy((*new_auth_tok)->session_key.encrypted_key,
		       &data[(*packet_size)],
		       (*new_auth_tok)->session_key.encrypted_key_size);
		(*packet_size) +=
			(*new_auth_tok)->session_key.encrypted_key_size;
		(*new_auth_tok)->session_key.flags &=
			~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
		(*new_auth_tok)->session_key.flags |=
			ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
		(*new_auth_tok)->token.password.hash_algo = 0x01;
		break;
	default:
		ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
				"[%d]\n", data[(*packet_size) - 1]);
		rc = -ENOSYS;
		goto out_free;
	}
	(*new_auth_tok)->token_type = ECRYPTFS_PASSWORD;
	/* TODO: Parametarize; we might actually want userspace to
	 * decrypt the session key. */
	(*new_auth_tok)->session_key.flags &=
			    ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
	(*new_auth_tok)->session_key.flags &=
			    ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
	list_add(&auth_tok_list_item->list, auth_tok_list);
	goto out;
out_free:
	(*new_auth_tok) = NULL;
	memset(auth_tok_list_item, 0,
	       sizeof(struct ecryptfs_auth_tok_list_item));
	kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
			auth_tok_list_item);
out:
	if (rc)
		(*packet_size) = 0;
	return rc;
}

/**
 * parse_tag_11_packet
 * @data: The raw bytes of the packet
 * @contents: This function writes the data contents of the literal
 *            packet into this memory location
 * @max_contents_bytes: The maximum number of bytes that this function
 *                      is allowed to write into contents
 * @tag_11_contents_size: This function writes the size of the parsed
 *                        contents into this memory location; zero on
 *                        error
 * @packet_size: This function writes the size of the parsed packet
 *               into this memory location; zero on error
 * @max_packet_size: maximum number of bytes to parse
 *
 * Returns zero on success; non-zero on error.
 */
static int
parse_tag_11_packet(unsigned char *data, unsigned char *contents,
		    size_t max_contents_bytes, size_t *tag_11_contents_size,
		    size_t *packet_size, size_t max_packet_size)
{
	size_t body_size;
	size_t length_size;
	int rc = 0;

	(*packet_size) = 0;
	(*tag_11_contents_size) = 0;

	/* check that:
	 *   one byte for the Tag 11 ID flag
	 *   two bytes for the Tag 11 length
	 * do not exceed the maximum_packet_size
	 */
	if (unlikely((*packet_size) + 3 > max_packet_size)) {
		ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
		rc = -EINVAL;
		goto out;
	}

	/* check for Tag 11 identifyer - one byte */
	if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
		ecryptfs_printk(KERN_WARNING,
				"Invalid tag 11 packet format\n");
		rc = -EINVAL;
		goto out;
	}

	/* get Tag 11 content length - one or two bytes */
	rc = parse_packet_length(&data[(*packet_size)], &body_size,
				 &length_size);
	if (rc) {
		ecryptfs_printk(KERN_WARNING,
				"Invalid tag 11 packet format\n");
		goto out;
	}
	(*packet_size) += length_size;

	if (body_size < 13) {
		ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n",
				body_size);
		rc = -EINVAL;
		goto out;
	}
	/* We have 13 bytes of surrounding packet values */
	(*tag_11_contents_size) = (body_size - 13);

	/* now we know the length of the remainting Tag 11 packet size:
	 *   14 fix bytes for: special flag one, special flag two,
	 *   		       12 skipped bytes
	 *   body_size bytes minus the stuff above is the Tag 11 content
	 */
	/* FIXME why is the body size one byte smaller than the actual
	 * size of the body?
	 * this seems to be an error here as well as in
	 * write_tag_11_packet() */
	if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
		ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
		rc = -EINVAL;
		goto out;
	}

	/* special flag one - one byte */
	if (data[(*packet_size)++] != 0x62) {
		ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n");
		rc = -EINVAL;
		goto out;
	}

	/* special flag two - one byte */
	if (data[(*packet_size)++] != 0x08) {
		ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n");
		rc = -EINVAL;
		goto out;
	}

	/* skip the next 12 bytes */
	(*packet_size) += 12; /* We don't care about the filename or
			       * the timestamp */

	/* get the Tag 11 contents - tag_11_contents_size bytes */
	memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size));
	(*packet_size) += (*tag_11_contents_size);

out:
	if (rc) {
		(*packet_size) = 0;
		(*tag_11_contents_size) = 0;
	}
	return rc;
}

static int
ecryptfs_find_global_auth_tok_for_sig(
	struct ecryptfs_global_auth_tok **global_auth_tok,
	struct ecryptfs_mount_crypt_stat *mount_crypt_stat, char *sig)
{
	struct ecryptfs_global_auth_tok *walker;
	int rc = 0;

	(*global_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) == 0) {
			(*global_auth_tok) = walker;
			goto out;
		}
	}
	rc = -EINVAL;
out:
	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
	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;
}

int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key,
				      struct ecryptfs_auth_tok **auth_tok,
				      char *sig)
{
	int rc = 0;

	(*auth_tok_key) = request_key(&key_type_user, sig, NULL);
	if (!(*auth_tok_key) || IS_ERR(*auth_tok_key)) {
		printk(KERN_ERR "Could not find key with description: [%s]\n",
		       sig);
		process_request_key_err(PTR_ERR(*auth_tok_key));
		rc = -EINVAL;
		goto out;
	}
	(*auth_tok) = ecryptfs_get_key_payload_data(*auth_tok_key);
	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;
}

/**
 * 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 ecryptfs_auth_tok **auth_tok,
	struct ecryptfs_crypt_stat *crypt_stat, char *sig)
{
	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
		crypt_stat->mount_crypt_stat;
	struct ecryptfs_global_auth_tok *global_auth_tok;
	int rc = 0;

	(*auth_tok) = NULL;
	if (ecryptfs_find_global_auth_tok_for_sig(&global_auth_tok,
						  mount_crypt_stat, sig)) {
		struct key *auth_tok_key;

		rc = ecryptfs_keyring_auth_tok_for_sig(&auth_tok_key, auth_tok,
						       sig);
	} else
		(*auth_tok) = global_auth_tok->global_auth_tok;
	return rc;
}

/**
 * decrypt_passphrase_encrypted_session_key - Decrypt the session key
 * with the given auth_tok.
 *
 * Returns Zero on success; non-zero error otherwise.
 */
static int
decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
					 struct ecryptfs_crypt_stat *crypt_stat)
{
	struct scatterlist dst_sg;
	struct scatterlist src_sg;
	struct mutex *tfm_mutex = NULL;
	struct blkcipher_desc desc = {
		.flags = CRYPTO_TFM_REQ_MAY_SLEEP
	};
	int rc = 0;

	if (unlikely(ecryptfs_verbosity > 0)) {
		ecryptfs_printk(
			KERN_DEBUG, "Session key encryption key (size [%d]):\n",
			auth_tok->token.password.session_key_encryption_key_bytes);
		ecryptfs_dump_hex(
			auth_tok->token.password.session_key_encryption_key,
			auth_tok->token.password.session_key_encryption_key_bytes);
	}
	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
							crypt_stat->cipher);
	if (unlikely(rc)) {
		printk(KERN_ERR "Internal error whilst attempting to get "
		       "tfm and mutex for cipher name [%s]; rc = [%d]\n",
		       crypt_stat->cipher, rc);
		goto out;
	}
	if ((rc = virt_to_scatterlist(auth_tok->session_key.encrypted_key,
				      auth_tok->session_key.encrypted_key_size,
				      &src_sg, 1)) != 1) {
		printk(KERN_ERR "Internal error whilst attempting to convert "
			"auth_tok->session_key.encrypted_key to scatterlist; "
			"expected rc = 1; got rc = [%d]. "
		       "auth_tok->session_key.encrypted_key_size = [%d]\n", rc,
			auth_tok->session_key.encrypted_key_size);
		goto out;
	}
	auth_tok->session_key.decrypted_key_size =
		auth_tok->session_key.encrypted_key_size;
	if ((rc = virt_to_scatterlist(auth_tok->session_key.decrypted_key,
				      auth_tok->session_key.decrypted_key_size,
				      &dst_sg, 1)) != 1) {
		printk(KERN_ERR "Internal error whilst attempting to convert "
			"auth_tok->session_key.decrypted_key to scatterlist; "
			"expected rc = 1; got rc = [%d]\n", rc);
		goto out;
	}
	mutex_lock(tfm_mutex);
	rc = crypto_blkcipher_setkey(
		desc.tfm, auth_tok->token.password.session_key_encryption_key,
		crypt_stat->key_size);
	if (unlikely(rc < 0)) {
		mutex_unlock(tfm_mutex);
		printk(KERN_ERR "Error setting key for crypto context\n");
		rc = -EINVAL;
		goto out;
	}
	rc = crypto_blkcipher_decrypt(&desc, &dst_sg, &src_sg,
				      auth_tok->session_key.encrypted_key_size);
	mutex_unlock(tfm_mutex);
	if (unlikely(rc)) {
		printk(KERN_ERR "Error decrypting; rc = [%d]\n", rc);
		goto out;
	}
	auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
	memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
	       auth_tok->session_key.decrypted_key_size);
	crypt_stat->flags |= ECRYPTFS_KEY_VALID;
	if (unlikely(ecryptfs_verbosity > 0)) {
		ecryptfs_printk(KERN_DEBUG, "FEK of size [%d]:\n",
				crypt_stat->key_size);
		ecryptfs_dump_hex(crypt_stat->key,
				  crypt_stat->key_size);
	}
out:
	return rc;
}

int ecryptfs_get_auth_tok_sig(char **sig, struct ecryptfs_auth_tok *auth_tok)
{
	int rc = 0;

	(*sig) = NULL;
	switch (auth_tok->token_type) {
	case ECRYPTFS_PASSWORD:
		(*sig) = auth_tok->token.password.signature;
		break;
	case ECRYPTFS_PRIVATE_KEY:
		(*sig) = auth_tok->token.private_key.signature;
		break;
	default:
		printk(KERN_ERR "Cannot get sig for auth_tok of type [%d]\n",
		       auth_tok->token_type);
		rc = -EINVAL;
	}
	return rc;
}

/**
 * ecryptfs_parse_packet_set
 * @dest: The header page in memory
 * @version: Version of file format, to guide parsing behavior
 *
 * Get crypt_stat to have the file's session key if the requisite key
 * is available to decrypt the session key.
 *
 * Returns Zero if a valid authentication token was retrieved and
 * processed; negative value for file not encrypted or for error
 * conditions.
 */
int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
			      unsigned char *src,
			      struct dentry *ecryptfs_dentry)
{
	size_t i = 0;
	size_t found_auth_tok;
	size_t next_packet_is_auth_tok_packet;
	struct list_head auth_tok_list;
	struct ecryptfs_auth_tok *matching_auth_tok = NULL;
	struct ecryptfs_auth_tok *candidate_auth_tok = NULL;
	char *candidate_auth_tok_sig;
	size_t packet_size;
	struct ecryptfs_auth_tok *new_auth_tok;
	unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
	struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
	size_t tag_11_contents_size;
	size_t tag_11_packet_size;
	int rc = 0;

	INIT_LIST_HEAD(&auth_tok_list);
	/* Parse the header to find as many packets as we can; these will be
	 * added the our &auth_tok_list */
	next_packet_is_auth_tok_packet = 1;
	while (next_packet_is_auth_tok_packet) {
		size_t max_packet_size = ((PAGE_CACHE_SIZE - 8) - i);

		switch (src[i]) {
		case ECRYPTFS_TAG_3_PACKET_TYPE:
			rc = parse_tag_3_packet(crypt_stat,
						(unsigned char *)&src[i],
						&auth_tok_list, &new_auth_tok,
						&packet_size, max_packet_size);
			if (rc) {
				ecryptfs_printk(KERN_ERR, "Error parsing "
						"tag 3 packet\n");
				rc = -EIO;
				goto out_wipe_list;
			}
			i += packet_size;
			rc = parse_tag_11_packet((unsigned char *)&src[i],
						 sig_tmp_space,
						 ECRYPTFS_SIG_SIZE,
						 &tag_11_contents_size,
						 &tag_11_packet_size,
						 max_packet_size);
			if (rc) {
				ecryptfs_printk(KERN_ERR, "No valid "
						"(ecryptfs-specific) literal "
						"packet containing "
						"authentication token "
						"signature found after "
						"tag 3 packet\n");
				rc = -EIO;
				goto out_wipe_list;
			}
			i += tag_11_packet_size;
			if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
				ecryptfs_printk(KERN_ERR, "Expected "
						"signature of size [%d]; "
						"read size [%d]\n",
						ECRYPTFS_SIG_SIZE,
						tag_11_contents_size);
				rc = -EIO;
				goto out_wipe_list;
			}
			ecryptfs_to_hex(new_auth_tok->token.password.signature,
					sig_tmp_space, tag_11_contents_size);
			new_auth_tok->token.password.signature[
				ECRYPTFS_PASSWORD_SIG_SIZE] = '\0';
			crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
			break;
		case ECRYPTFS_TAG_1_PACKET_TYPE:
			rc = parse_tag_1_packet(crypt_stat,
						(unsigned char *)&src[i],
						&auth_tok_list, &new_auth_tok,
						&packet_size, max_packet_size);
			if (rc) {
				ecryptfs_printk(KERN_ERR, "Error parsing "
						"tag 1 packet\n");
				rc = -EIO;
				goto out_wipe_list;
			}
			i += packet_size;
			crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
			break;
		case ECRYPTFS_TAG_11_PACKET_TYPE:
			ecryptfs_printk(KERN_WARNING, "Invalid packet set "
					"(Tag 11 not allowed by itself)\n");
			rc = -EIO;
			goto out_wipe_list;
			break;
		default:
			ecryptfs_printk(KERN_DEBUG, "No packet at offset "
					"[%d] of the file header; hex value of "
					"character is [0x%.2x]\n", i, src[i]);
			next_packet_is_auth_tok_packet = 0;
		}
	}
	if (list_empty(&auth_tok_list)) {
		printk(KERN_ERR "The lower file appears to be a non-encrypted "
		       "eCryptfs file; this is not supported in this version "
		       "of the eCryptfs kernel module\n");
		rc = -EINVAL;
		goto out;
	}
	/* auth_tok_list contains the set of authentication tokens
	 * parsed from the metadata. We need to find a matching
	 * authentication token that has the secret component(s)
	 * necessary to decrypt the EFEK in the auth_tok parsed from
	 * the metadata. There may be several potential matches, but
	 * just one will be sufficient to decrypt to get the FEK. */
find_next_matching_auth_tok:
	found_auth_tok = 0;
	list_for_each_entry(auth_tok_list_item, &auth_tok_list, list) {
		candidate_auth_tok = &auth_tok_list_item->auth_tok;
		if (unlikely(ecryptfs_verbosity > 0)) {
			ecryptfs_printk(KERN_DEBUG,
					"Considering cadidate auth tok:\n");
			ecryptfs_dump_auth_tok(candidate_auth_tok);
		}
		if ((rc = ecryptfs_get_auth_tok_sig(&candidate_auth_tok_sig,
						    candidate_auth_tok))) {
			printk(KERN_ERR
			       "Unrecognized candidate auth tok type: [%d]\n",
			       candidate_auth_tok->token_type);
			rc = -EINVAL;
			goto out_wipe_list;
		}
		if ((rc = ecryptfs_find_auth_tok_for_sig(
			     &matching_auth_tok, crypt_stat,
			     candidate_auth_tok_sig)))
			rc = 0;
		if (matching_auth_tok) {
			found_auth_tok = 1;
			goto found_matching_auth_tok;
		}
	}
	if (!found_auth_tok) {
		ecryptfs_printk(KERN_ERR, "Could not find a usable "
				"authentication token\n");
		rc = -EIO;
		goto out_wipe_list;
	}
found_matching_auth_tok:
	if (candidate_auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
		memcpy(&(candidate_auth_tok->token.private_key),
		       &(matching_auth_tok->token.private_key),
		       sizeof(struct ecryptfs_private_key));
		rc = decrypt_pki_encrypted_session_key(candidate_auth_tok,
						       crypt_stat);
	} else if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD) {
		memcpy(&(candidate_auth_tok->token.password),
		       &(matching_auth_tok->token.password),
		       sizeof(struct ecryptfs_password));
		rc = decrypt_passphrase_encrypted_session_key(
			candidate_auth_tok, crypt_stat);
	}
	if (rc) {
		struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;

		ecryptfs_printk(KERN_WARNING, "Error decrypting the "
				"session key for authentication token with sig "
				"[%.*s]; rc = [%d]. Removing auth tok "
				"candidate from the list and searching for "
				"the next match.\n", candidate_auth_tok_sig,
				ECRYPTFS_SIG_SIZE_HEX, rc);
		list_for_each_entry_safe(auth_tok_list_item,
					 auth_tok_list_item_tmp,
					 &auth_tok_list, list) {
			if (candidate_auth_tok
			    == &auth_tok_list_item->auth_tok) {
				list_del(&auth_tok_list_item->list);
				kmem_cache_free(
					ecryptfs_auth_tok_list_item_cache,
					auth_tok_list_item);
				goto find_next_matching_auth_tok;
			}
		}
		BUG();
	}
	rc = ecryptfs_compute_root_iv(crypt_stat);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error computing "
				"the root IV\n");
		goto out_wipe_list;
	}
	rc = ecryptfs_init_crypt_ctx(crypt_stat);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error initializing crypto "
				"context for cipher [%s]; rc = [%d]\n",
				crypt_stat->cipher, rc);
	}
out_wipe_list:
	wipe_auth_tok_list(&auth_tok_list);
out:
	return rc;
}

static int
pki_encrypt_session_key(struct ecryptfs_auth_tok *auth_tok,
			struct ecryptfs_crypt_stat *crypt_stat,
			struct ecryptfs_key_record *key_rec)
{
	struct ecryptfs_msg_ctx *msg_ctx = NULL;
	char *netlink_payload;
	size_t netlink_payload_length;
	struct ecryptfs_message *msg;
	int rc;

	rc = write_tag_66_packet(auth_tok->token.private_key.signature,
				 ecryptfs_code_for_cipher_string(crypt_stat),
				 crypt_stat, &netlink_payload,
				 &netlink_payload_length);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet\n");
		goto out;
	}
	rc = ecryptfs_send_message(ecryptfs_transport, netlink_payload,
				   netlink_payload_length, &msg_ctx);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error sending netlink message\n");
		goto out;
	}
	rc = ecryptfs_wait_for_response(msg_ctx, &msg);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Failed to receive tag 67 packet "
				"from the user space daemon\n");
		rc = -EIO;
		goto out;
	}
	rc = parse_tag_67_packet(key_rec, msg);
	if (rc)
		ecryptfs_printk(KERN_ERR, "Error parsing tag 67 packet\n");
	kfree(msg);
out:
	if (netlink_payload)
		kfree(netlink_payload);
	return rc;
}
/**
 * write_tag_1_packet - Write an RFC2440-compatible tag 1 (public key) packet
 * @dest: Buffer into which to write the packet
 * @max: Maximum number of bytes that can be writtn
 * @packet_size: This function will write the number of bytes that end
 *               up constituting the packet; set to zero on error
 *
 * Returns zero on success; non-zero on error.
 */
static int
write_tag_1_packet(char *dest, size_t *remaining_bytes,
		   struct ecryptfs_auth_tok *auth_tok,
		   struct ecryptfs_crypt_stat *crypt_stat,
		   struct ecryptfs_key_record *key_rec, size_t *packet_size)
{
	size_t i;
	size_t encrypted_session_key_valid = 0;
	size_t packet_size_length;
	size_t max_packet_size;
	int rc = 0;

	(*packet_size) = 0;
	ecryptfs_from_hex(key_rec->sig, auth_tok->token.private_key.signature,
			  ECRYPTFS_SIG_SIZE);
	encrypted_session_key_valid = 0;
	for (i = 0; i < crypt_stat->key_size; i++)
		encrypted_session_key_valid |=
			auth_tok->session_key.encrypted_key[i];
	if (encrypted_session_key_valid) {
		memcpy(key_rec->enc_key,
		       auth_tok->session_key.encrypted_key,
		       auth_tok->session_key.encrypted_key_size);
		goto encrypted_session_key_set;
	}
	if (auth_tok->session_key.encrypted_key_size == 0)
		auth_tok->session_key.encrypted_key_size =
			auth_tok->token.private_key.key_size;
	rc = pki_encrypt_session_key(auth_tok, crypt_stat, key_rec);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Failed to encrypt session key "
				"via a pki");
		goto out;
	}
	if (ecryptfs_verbosity > 0) {
		ecryptfs_printk(KERN_DEBUG, "Encrypted key:\n");
		ecryptfs_dump_hex(key_rec->enc_key, key_rec->enc_key_size);
	}
encrypted_session_key_set:
	/* This format is inspired by OpenPGP; see RFC 2440
	 * packet tag 1 */
	max_packet_size = (1                         /* Tag 1 identifier */
			   + 3                       /* Max Tag 1 packet size */
			   + 1                       /* Version */
			   + ECRYPTFS_SIG_SIZE       /* Key identifier */
			   + 1                       /* Cipher identifier */
			   + key_rec->enc_key_size); /* Encrypted key size */
	if (max_packet_size > (*remaining_bytes)) {
		printk(KERN_ERR "Packet length larger than maximum allowable; "
		       "need up to [%d] bytes, but there are only [%d] "
		       "available\n", max_packet_size, (*remaining_bytes));
		rc = -EINVAL;
		goto out;
	}
	dest[(*packet_size)++] = ECRYPTFS_TAG_1_PACKET_TYPE;
	rc = write_packet_length(&dest[(*packet_size)], (max_packet_size - 4),
				 &packet_size_length);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error generating tag 1 packet "
				"header; cannot generate packet length\n");
		goto out;
	}
	(*packet_size) += packet_size_length;
	dest[(*packet_size)++] = 0x03; /* version 3 */
	memcpy(&dest[(*packet_size)], key_rec->sig, ECRYPTFS_SIG_SIZE);
	(*packet_size) += ECRYPTFS_SIG_SIZE;
	dest[(*packet_size)++] = RFC2440_CIPHER_RSA;
	memcpy(&dest[(*packet_size)], key_rec->enc_key,
	       key_rec->enc_key_size);
	(*packet_size) += key_rec->enc_key_size;
out:
	if (rc)
		(*packet_size) = 0;
	else
		(*remaining_bytes) -= (*packet_size);
	return rc;
}

/**
 * write_tag_11_packet
 * @dest: Target into which Tag 11 packet is to be written
 * @max: Maximum packet length
 * @contents: Byte array of contents to copy in
 * @contents_length: Number of bytes in contents
 * @packet_length: Length of the Tag 11 packet written; zero on error
 *
 * Returns zero on success; non-zero on error.
 */
static int
write_tag_11_packet(char *dest, int max, char *contents, size_t contents_length,
		    size_t *packet_length)
{
	size_t packet_size_length;
	int rc = 0;

	(*packet_length) = 0;
	if ((13 + contents_length) > max) {
		rc = -EINVAL;
		ecryptfs_printk(KERN_ERR, "Packet length larger than "
				"maximum allowable\n");
		goto out;
	}
	/* General packet header */
	/* Packet tag */
	dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
	/* Packet length */
	rc = write_packet_length(&dest[(*packet_length)],
				 (13 + contents_length), &packet_size_length);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error generating tag 11 packet "
				"header; cannot generate packet length\n");
		goto out;
	}
	(*packet_length) += packet_size_length;
	/* Tag 11 specific */
	/* One-octet field that describes how the data is formatted */
	dest[(*packet_length)++] = 0x62; /* binary data */
	/* One-octet filename length followed by filename */
	dest[(*packet_length)++] = 8;
	memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
	(*packet_length) += 8;
	/* Four-octet number indicating modification date */
	memset(&dest[(*packet_length)], 0x00, 4);
	(*packet_length) += 4;
	/* Remainder is literal data */
	memcpy(&dest[(*packet_length)], contents, contents_length);
	(*packet_length) += contents_length;
 out:
	if (rc)
		(*packet_length) = 0;
	return rc;
}

/**
 * write_tag_3_packet
 * @dest: Buffer into which to write the packet
 * @max: Maximum number of bytes that can be written
 * @auth_tok: Authentication token
 * @crypt_stat: The cryptographic context
 * @key_rec: encrypted key
 * @packet_size: This function will write the number of bytes that end
 *               up constituting the packet; set to zero on error
 *
 * Returns zero on success; non-zero on error.
 */
static int
write_tag_3_packet(char *dest, size_t *remaining_bytes,
		   struct ecryptfs_auth_tok *auth_tok,
		   struct ecryptfs_crypt_stat *crypt_stat,
		   struct ecryptfs_key_record *key_rec, size_t *packet_size)
{
	size_t i;
	size_t encrypted_session_key_valid = 0;
	char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
	struct scatterlist dst_sg;
	struct scatterlist src_sg;
	struct mutex *tfm_mutex = NULL;
	size_t cipher_code;
	size_t packet_size_length;
	size_t max_packet_size;
	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
		crypt_stat->mount_crypt_stat;
	struct blkcipher_desc desc = {
		.tfm = NULL,
		.flags = CRYPTO_TFM_REQ_MAY_SLEEP
	};
	int rc = 0;

	(*packet_size) = 0;
	ecryptfs_from_hex(key_rec->sig, auth_tok->token.password.signature,
			  ECRYPTFS_SIG_SIZE);
	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
							crypt_stat->cipher);
	if (unlikely(rc)) {
		printk(KERN_ERR "Internal error whilst attempting to get "
		       "tfm and mutex for cipher name [%s]; rc = [%d]\n",
		       crypt_stat->cipher, rc);
		goto out;
	}
	if (mount_crypt_stat->global_default_cipher_key_size == 0) {
		struct blkcipher_alg *alg = crypto_blkcipher_alg(desc.tfm);

		printk(KERN_WARNING "No key size specified at mount; "
		       "defaulting to [%d]\n", alg->max_keysize);
		mount_crypt_stat->global_default_cipher_key_size =
			alg->max_keysize;
	}
	if (crypt_stat->key_size == 0)
		crypt_stat->key_size =
			mount_crypt_stat->global_default_cipher_key_size;
	if (auth_tok->session_key.encrypted_key_size == 0)
		auth_tok->session_key.encrypted_key_size =
			crypt_stat->key_size;
	if (crypt_stat->key_size == 24
	    && strcmp("aes", crypt_stat->cipher) == 0) {
		memset((crypt_stat->key + 24), 0, 8);
		auth_tok->session_key.encrypted_key_size = 32;
	} else
		auth_tok->session_key.encrypted_key_size = crypt_stat->key_size;
	key_rec->enc_key_size =
		auth_tok->session_key.encrypted_key_size;
	encrypted_session_key_valid = 0;
	for (i = 0; i < auth_tok->session_key.encrypted_key_size; i++)
		encrypted_session_key_valid |=
			auth_tok->session_key.encrypted_key[i];
	if (encrypted_session_key_valid) {
		ecryptfs_printk(KERN_DEBUG, "encrypted_session_key_valid != 0; "
				"using auth_tok->session_key.encrypted_key, "
				"where key_rec->enc_key_size = [%d]\n",
				key_rec->enc_key_size);
		memcpy(key_rec->enc_key,
		       auth_tok->session_key.encrypted_key,
		       key_rec->enc_key_size);
		goto encrypted_session_key_set;
	}
	if (auth_tok->token.password.flags &
	    ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET) {
		ecryptfs_printk(KERN_DEBUG, "Using previously generated "
				"session key encryption key of size [%d]\n",
				auth_tok->token.password.
				session_key_encryption_key_bytes);
		memcpy(session_key_encryption_key,
		       auth_tok->token.password.session_key_encryption_key,
		       crypt_stat->key_size);
		ecryptfs_printk(KERN_DEBUG,
				"Cached session key " "encryption key: \n");
		if (ecryptfs_verbosity > 0)
			ecryptfs_dump_hex(session_key_encryption_key, 16);
	}
	if (unlikely(ecryptfs_verbosity > 0)) {
		ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n");
		ecryptfs_dump_hex(session_key_encryption_key, 16);
	}
	if ((rc = virt_to_scatterlist(crypt_stat->key,
				      key_rec->enc_key_size, &src_sg, 1))
	    != 1) {
		ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
				"for crypt_stat session key; expected rc = 1; "
				"got rc = [%d]. key_rec->enc_key_size = [%d]\n",
				rc, key_rec->enc_key_size);
		rc = -ENOMEM;
		goto out;
	}
	if ((rc = virt_to_scatterlist(key_rec->enc_key,
				      key_rec->enc_key_size, &dst_sg, 1))
	    != 1) {
		ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
				"for crypt_stat encrypted session key; "
				"expected rc = 1; got rc = [%d]. "
				"key_rec->enc_key_size = [%d]\n", rc,
				key_rec->enc_key_size);
		rc = -ENOMEM;
		goto out;
	}
	mutex_lock(tfm_mutex);
	rc = crypto_blkcipher_setkey(desc.tfm, session_key_encryption_key,
				     crypt_stat->key_size);
	if (rc < 0) {
		mutex_unlock(tfm_mutex);
		ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
				"context; rc = [%d]\n", rc);
		goto out;
	}
	rc = 0;
	ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes of the key\n",
			crypt_stat->key_size);
	rc = crypto_blkcipher_encrypt(&desc, &dst_sg, &src_sg,
				      (*key_rec).enc_key_size);
	mutex_unlock(tfm_mutex);
	if (rc) {
		printk(KERN_ERR "Error encrypting; rc = [%d]\n", rc);
		goto out;
	}
	ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
	if (ecryptfs_verbosity > 0) {
		ecryptfs_printk(KERN_DEBUG, "EFEK of size [%d]:\n",
				key_rec->enc_key_size);
		ecryptfs_dump_hex(key_rec->enc_key,
				  key_rec->enc_key_size);
	}
encrypted_session_key_set:
	/* This format is inspired by OpenPGP; see RFC 2440
	 * packet tag 3 */
	max_packet_size = (1                         /* Tag 3 identifier */
			   + 3                       /* Max Tag 3 packet size */
			   + 1                       /* Version */
			   + 1                       /* Cipher code */
			   + 1                       /* S2K specifier */
			   + 1                       /* Hash identifier */
			   + ECRYPTFS_SALT_SIZE      /* Salt */
			   + 1                       /* Hash iterations */
			   + key_rec->enc_key_size); /* Encrypted key size */
	if (max_packet_size > (*remaining_bytes)) {
		printk(KERN_ERR "Packet too large; need up to [%d] bytes, but "
		       "there are only [%d] available\n", max_packet_size,
		       (*remaining_bytes));
		rc = -EINVAL;
		goto out;
	}
	dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
	/* Chop off the Tag 3 identifier(1) and Tag 3 packet size(3)
	 * to get the number of octets in the actual Tag 3 packet */
	rc = write_packet_length(&dest[(*packet_size)], (max_packet_size - 4),
				 &packet_size_length);
	if (rc) {
		printk(KERN_ERR "Error generating tag 3 packet header; cannot "
		       "generate packet length. rc = [%d]\n", rc);
		goto out;
	}
	(*packet_size) += packet_size_length;
	dest[(*packet_size)++] = 0x04; /* version 4 */
	/* TODO: Break from RFC2440 so that arbitrary ciphers can be
	 * specified with strings */
	cipher_code = ecryptfs_code_for_cipher_string(crypt_stat);
	if (cipher_code == 0) {
		ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
				"cipher [%s]\n", crypt_stat->cipher);
		rc = -EINVAL;
		goto out;
	}
	dest[(*packet_size)++] = cipher_code;
	dest[(*packet_size)++] = 0x03;	/* S2K */
	dest[(*packet_size)++] = 0x01;	/* MD5 (TODO: parameterize) */
	memcpy(&dest[(*packet_size)], auth_tok->token.password.salt,
	       ECRYPTFS_SALT_SIZE);
	(*packet_size) += ECRYPTFS_SALT_SIZE;	/* salt */
	dest[(*packet_size)++] = 0x60;	/* hash iterations (65536) */
	memcpy(&dest[(*packet_size)], key_rec->enc_key,
	       key_rec->enc_key_size);
	(*packet_size) += key_rec->enc_key_size;
out:
	if (rc)
		(*packet_size) = 0;
	else
		(*remaining_bytes) -= (*packet_size);
	return rc;
}

struct kmem_cache *ecryptfs_key_record_cache;

/**
 * ecryptfs_generate_key_packet_set
 * @dest: Virtual address from which to write the key record set
 * @crypt_stat: The cryptographic context from which the
 *              authentication tokens will be retrieved
 * @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat
 *                   for the global parameters
 * @len: The amount written
 * @max: The maximum amount of data allowed to be written
 *
 * Generates a key packet set and writes it to the virtual address
 * passed in.
 *
 * Returns zero on success; non-zero on error.
 */
int
ecryptfs_generate_key_packet_set(char *dest_base,
				 struct ecryptfs_crypt_stat *crypt_stat,
				 struct dentry *ecryptfs_dentry, size_t *len,
				 size_t max)
{
	struct ecryptfs_auth_tok *auth_tok;
	struct ecryptfs_global_auth_tok *global_auth_tok;
	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
		&ecryptfs_superblock_to_private(
			ecryptfs_dentry->d_sb)->mount_crypt_stat;
	size_t written;
	struct ecryptfs_key_record *key_rec;
	struct ecryptfs_key_sig *key_sig;
	int rc = 0;

	(*len) = 0;
	mutex_lock(&crypt_stat->keysig_list_mutex);
	key_rec = kmem_cache_alloc(ecryptfs_key_record_cache, GFP_KERNEL);
	if (!key_rec) {
		rc = -ENOMEM;
		goto out;
	}
	list_for_each_entry(key_sig, &crypt_stat->keysig_list,
			    crypt_stat_list) {
		memset(key_rec, 0, sizeof(*key_rec));
		rc = ecryptfs_find_global_auth_tok_for_sig(&global_auth_tok,
							   mount_crypt_stat,
							   key_sig->keysig);
		if (rc) {
			printk(KERN_ERR "Error attempting to get the global "
			       "auth_tok; rc = [%d]\n", rc);
			goto out_free;
		}
		if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID) {
			printk(KERN_WARNING
			       "Skipping invalid auth tok with sig = [%s]\n",
			       global_auth_tok->sig);
			continue;
		}
		auth_tok = global_auth_tok->global_auth_tok;
		if (auth_tok->token_type == ECRYPTFS_PASSWORD) {
			rc = write_tag_3_packet((dest_base + (*len)),
						&max, auth_tok,
						crypt_stat, key_rec,
						&written);
			if (rc) {
				ecryptfs_printk(KERN_WARNING, "Error "
						"writing tag 3 packet\n");
				goto out_free;
			}
			(*len) += written;
			/* Write auth tok signature packet */
			rc = write_tag_11_packet((dest_base + (*len)), &max,
						 key_rec->sig,
						 ECRYPTFS_SIG_SIZE, &written);
			if (rc) {
				ecryptfs_printk(KERN_ERR, "Error writing "
						"auth tok signature packet\n");
				goto out_free;
			}
			(*len) += written;
		} else if (auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
			rc = write_tag_1_packet(dest_base + (*len),
						&max, auth_tok,
						crypt_stat, key_rec, &written);
			if (rc) {
				ecryptfs_printk(KERN_WARNING, "Error "
						"writing tag 1 packet\n");
				goto out_free;
			}
			(*len) += written;
		} else {
			ecryptfs_printk(KERN_WARNING, "Unsupported "
					"authentication token type\n");
			rc = -EINVAL;
			goto out_free;
		}
	}
	if (likely(max > 0)) {
		dest_base[(*len)] = 0x00;
	} else {
		ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
		rc = -EIO;
	}
out_free:
	kmem_cache_free(ecryptfs_key_record_cache, key_rec);
out:
	if (rc)
		(*len) = 0;
	mutex_unlock(&crypt_stat->keysig_list_mutex);
	return rc;
}

struct kmem_cache *ecryptfs_key_sig_cache;

int ecryptfs_add_keysig(struct ecryptfs_crypt_stat *crypt_stat, char *sig)
{
	struct ecryptfs_key_sig *new_key_sig;
	int rc = 0;

	new_key_sig = kmem_cache_alloc(ecryptfs_key_sig_cache, GFP_KERNEL);
	if (!new_key_sig) {
		rc = -ENOMEM;
		printk(KERN_ERR
		       "Error allocating from ecryptfs_key_sig_cache\n");
		goto out;
	}
	memcpy(new_key_sig->keysig, sig, ECRYPTFS_SIG_SIZE_HEX);
	mutex_lock(&crypt_stat->keysig_list_mutex);
	list_add(&new_key_sig->crypt_stat_list, &crypt_stat->keysig_list);
	mutex_unlock(&crypt_stat->keysig_list_mutex);
out:
	return rc;
}

struct kmem_cache *ecryptfs_global_auth_tok_cache;

int
ecryptfs_add_global_auth_tok(struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
			     char *sig)
{
	struct ecryptfs_global_auth_tok *new_auth_tok;
	int rc = 0;

	new_auth_tok = kmem_cache_alloc(ecryptfs_global_auth_tok_cache,
					GFP_KERNEL);
	if (!new_auth_tok) {
		rc = -ENOMEM;
		printk(KERN_ERR "Error allocating from "
		       "ecryptfs_global_auth_tok_cache\n");
		goto out;
	}
	memcpy(new_auth_tok->sig, sig, ECRYPTFS_SIG_SIZE_HEX);
	new_auth_tok->sig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
	list_add(&new_auth_tok->mount_crypt_stat_list,
		 &mount_crypt_stat->global_auth_tok_list);
	mount_crypt_stat->num_global_auth_toks++;
	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
out:
	return rc;
}