aboutsummaryrefslogtreecommitdiff
path: root/security/keys/keyctl.c
blob: 741e4ba382df5c38fca63884daa2739ab1f85fb2 (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
// SPDX-License-Identifier: GPL-2.0-or-later
/* Userspace key control operations
 *
 * Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#include <linux/init.h>
#include <linux/sched.h>
#include <linux/sched/task.h>
#include <linux/slab.h>
#include <linux/syscalls.h>
#include <linux/key.h>
#include <linux/keyctl.h>
#include <linux/fs.h>
#include <linux/capability.h>
#include <linux/cred.h>
#include <linux/string.h>
#include <linux/err.h>
#include <linux/vmalloc.h>
#include <linux/security.h>
#include <linux/uio.h>
#include <linux/uaccess.h>
#include <keys/request_key_auth-type.h>
#include "internal.h"

#define KEY_MAX_DESC_SIZE 4096

static const unsigned char keyrings_capabilities[1] = {
	[0] = (KEYCTL_CAPS0_CAPABILITIES |
	       (IS_ENABLED(CONFIG_PERSISTENT_KEYRINGS)	? KEYCTL_CAPS0_PERSISTENT_KEYRINGS : 0) |
	       (IS_ENABLED(CONFIG_KEY_DH_OPERATIONS)	? KEYCTL_CAPS0_DIFFIE_HELLMAN : 0) |
	       (IS_ENABLED(CONFIG_ASYMMETRIC_KEY_TYPE)	? KEYCTL_CAPS0_PUBLIC_KEY : 0) |
	       (IS_ENABLED(CONFIG_BIG_KEYS)		? KEYCTL_CAPS0_BIG_KEY : 0) |
	       KEYCTL_CAPS0_INVALIDATE |
	       KEYCTL_CAPS0_RESTRICT_KEYRING |
	       KEYCTL_CAPS0_MOVE
	       ),
};

static int key_get_type_from_user(char *type,
				  const char __user *_type,
				  unsigned len)
{
	int ret;

	ret = strncpy_from_user(type, _type, len);
	if (ret < 0)
		return ret;
	if (ret == 0 || ret >= len)
		return -EINVAL;
	if (type[0] == '.')
		return -EPERM;
	type[len - 1] = '\0';
	return 0;
}

/*
 * Extract the description of a new key from userspace and either add it as a
 * new key to the specified keyring or update a matching key in that keyring.
 *
 * If the description is NULL or an empty string, the key type is asked to
 * generate one from the payload.
 *
 * The keyring must be writable so that we can attach the key to it.
 *
 * If successful, the new key's serial number is returned, otherwise an error
 * code is returned.
 */
SYSCALL_DEFINE5(add_key, const char __user *, _type,
		const char __user *, _description,
		const void __user *, _payload,
		size_t, plen,
		key_serial_t, ringid)
{
	key_ref_t keyring_ref, key_ref;
	char type[32], *description;
	void *payload;
	long ret;

	ret = -EINVAL;
	if (plen > 1024 * 1024 - 1)
		goto error;

	/* draw all the data into kernel space */
	ret = key_get_type_from_user(type, _type, sizeof(type));
	if (ret < 0)
		goto error;

	description = NULL;
	if (_description) {
		description = strndup_user(_description, KEY_MAX_DESC_SIZE);
		if (IS_ERR(description)) {
			ret = PTR_ERR(description);
			goto error;
		}
		if (!*description) {
			kfree(description);
			description = NULL;
		} else if ((description[0] == '.') &&
			   (strncmp(type, "keyring", 7) == 0)) {
			ret = -EPERM;
			goto error2;
		}
	}

	/* pull the payload in if one was supplied */
	payload = NULL;

	if (plen) {
		ret = -ENOMEM;
		payload = kvmalloc(plen, GFP_KERNEL);
		if (!payload)
			goto error2;

		ret = -EFAULT;
		if (copy_from_user(payload, _payload, plen) != 0)
			goto error3;
	}

	/* find the target keyring (which must be writable) */
	keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
	if (IS_ERR(keyring_ref)) {
		ret = PTR_ERR(keyring_ref);
		goto error3;
	}

	/* create or update the requested key and add it to the target
	 * keyring */
	key_ref = key_create_or_update(keyring_ref, type, description,
				       payload, plen, KEY_PERM_UNDEF,
				       KEY_ALLOC_IN_QUOTA);
	if (!IS_ERR(key_ref)) {
		ret = key_ref_to_ptr(key_ref)->serial;
		key_ref_put(key_ref);
	}
	else {
		ret = PTR_ERR(key_ref);
	}

	key_ref_put(keyring_ref);
 error3:
	if (payload) {
		memzero_explicit(payload, plen);
		kvfree(payload);
	}
 error2:
	kfree(description);
 error:
	return ret;
}

/*
 * Search the process keyrings and keyring trees linked from those for a
 * matching key.  Keyrings must have appropriate Search permission to be
 * searched.
 *
 * If a key is found, it will be attached to the destination keyring if there's
 * one specified and the serial number of the key will be returned.
 *
 * If no key is found, /sbin/request-key will be invoked if _callout_info is
 * non-NULL in an attempt to create a key.  The _callout_info string will be
 * passed to /sbin/request-key to aid with completing the request.  If the
 * _callout_info string is "" then it will be changed to "-".
 */
SYSCALL_DEFINE4(request_key, const char __user *, _type,
		const char __user *, _description,
		const char __user *, _callout_info,
		key_serial_t, destringid)
{
	struct key_type *ktype;
	struct key *key;
	key_ref_t dest_ref;
	size_t callout_len;
	char type[32], *description, *callout_info;
	long ret;

	/* pull the type into kernel space */
	ret = key_get_type_from_user(type, _type, sizeof(type));
	if (ret < 0)
		goto error;

	/* pull the description into kernel space */
	description = strndup_user(_description, KEY_MAX_DESC_SIZE);
	if (IS_ERR(description)) {
		ret = PTR_ERR(description);
		goto error;
	}

	/* pull the callout info into kernel space */
	callout_info = NULL;
	callout_len = 0;
	if (_callout_info) {
		callout_info = strndup_user(_callout_info, PAGE_SIZE);
		if (IS_ERR(callout_info)) {
			ret = PTR_ERR(callout_info);
			goto error2;
		}
		callout_len = strlen(callout_info);
	}

	/* get the destination keyring if specified */
	dest_ref = NULL;
	if (destringid) {
		dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
					   KEY_NEED_WRITE);
		if (IS_ERR(dest_ref)) {
			ret = PTR_ERR(dest_ref);
			goto error3;
		}
	}

	/* find the key type */
	ktype = key_type_lookup(type);
	if (IS_ERR(ktype)) {
		ret = PTR_ERR(ktype);
		goto error4;
	}

	/* do the search */
	key = request_key_and_link(ktype, description, callout_info,
				   callout_len, NULL, key_ref_to_ptr(dest_ref),
				   KEY_ALLOC_IN_QUOTA);
	if (IS_ERR(key)) {
		ret = PTR_ERR(key);
		goto error5;
	}

	/* wait for the key to finish being constructed */
	ret = wait_for_key_construction(key, 1);
	if (ret < 0)
		goto error6;

	ret = key->serial;

error6:
 	key_put(key);
error5:
	key_type_put(ktype);
error4:
	key_ref_put(dest_ref);
error3:
	kfree(callout_info);
error2:
	kfree(description);
error:
	return ret;
}

/*
 * Get the ID of the specified process keyring.
 *
 * The requested keyring must have search permission to be found.
 *
 * If successful, the ID of the requested keyring will be returned.
 */
long keyctl_get_keyring_ID(key_serial_t id, int create)
{
	key_ref_t key_ref;
	unsigned long lflags;
	long ret;

	lflags = create ? KEY_LOOKUP_CREATE : 0;
	key_ref = lookup_user_key(id, lflags, KEY_NEED_SEARCH);
	if (IS_ERR(key_ref)) {
		ret = PTR_ERR(key_ref);
		goto error;
	}

	ret = key_ref_to_ptr(key_ref)->serial;
	key_ref_put(key_ref);
error:
	return ret;
}

/*
 * Join a (named) session keyring.
 *
 * Create and join an anonymous session keyring or join a named session
 * keyring, creating it if necessary.  A named session keyring must have Search
 * permission for it to be joined.  Session keyrings without this permit will
 * be skipped over.  It is not permitted for userspace to create or join
 * keyrings whose name begin with a dot.
 *
 * If successful, the ID of the joined session keyring will be returned.
 */
long keyctl_join_session_keyring(const char __user *_name)
{
	char *name;
	long ret;

	/* fetch the name from userspace */
	name = NULL;
	if (_name) {
		name = strndup_user(_name, KEY_MAX_DESC_SIZE);
		if (IS_ERR(name)) {
			ret = PTR_ERR(name);
			goto error;
		}

		ret = -EPERM;
		if (name[0] == '.')
			goto error_name;
	}

	/* join the session */
	ret = join_session_keyring(name);
error_name:
	kfree(name);
error:
	return ret;
}

/*
 * Update a key's data payload from the given data.
 *
 * The key must grant the caller Write permission and the key type must support
 * updating for this to work.  A negative key can be positively instantiated
 * with this call.
 *
 * If successful, 0 will be returned.  If the key type does not support
 * updating, then -EOPNOTSUPP will be returned.
 */
long keyctl_update_key(key_serial_t id,
		       const void __user *_payload,
		       size_t plen)
{
	key_ref_t key_ref;
	void *payload;
	long ret;

	ret = -EINVAL;
	if (plen > PAGE_SIZE)
		goto error;

	/* pull the payload in if one was supplied */
	payload = NULL;
	if (plen) {
		ret = -ENOMEM;
		payload = kmalloc(plen, GFP_KERNEL);
		if (!payload)
			goto error;

		ret = -EFAULT;
		if (copy_from_user(payload, _payload, plen) != 0)
			goto error2;
	}

	/* find the target key (which must be writable) */
	key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE);
	if (IS_ERR(key_ref)) {
		ret = PTR_ERR(key_ref);
		goto error2;
	}

	/* update the key */
	ret = key_update(key_ref, payload, plen);

	key_ref_put(key_ref);
error2:
	kzfree(payload);
error:
	return ret;
}

/*
 * Revoke a key.
 *
 * The key must be grant the caller Write or Setattr permission for this to
 * work.  The key type should give up its quota claim when revoked.  The key
 * and any links to the key will be automatically garbage collected after a
 * certain amount of time (/proc/sys/kernel/keys/gc_delay).
 *
 * Keys with KEY_FLAG_KEEP set should not be revoked.
 *
 * If successful, 0 is returned.
 */
long keyctl_revoke_key(key_serial_t id)
{
	key_ref_t key_ref;
	struct key *key;
	long ret;

	key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE);
	if (IS_ERR(key_ref)) {
		ret = PTR_ERR(key_ref);
		if (ret != -EACCES)
			goto error;
		key_ref = lookup_user_key(id, 0, KEY_NEED_SETATTR);
		if (IS_ERR(key_ref)) {
			ret = PTR_ERR(key_ref);
			goto error;
		}
	}

	key = key_ref_to_ptr(key_ref);
	ret = 0;
	if (test_bit(KEY_FLAG_KEEP, &key->flags))
		ret = -EPERM;
	else
		key_revoke(key);

	key_ref_put(key_ref);
error:
	return ret;
}

/*
 * Invalidate a key.
 *
 * The key must be grant the caller Invalidate permission for this to work.
 * The key and any links to the key will be automatically garbage collected
 * immediately.
 *
 * Keys with KEY_FLAG_KEEP set should not be invalidated.
 *
 * If successful, 0 is returned.
 */
long keyctl_invalidate_key(key_serial_t id)
{
	key_ref_t key_ref;
	struct key *key;
	long ret;

	kenter("%d", id);

	key_ref = lookup_user_key(id, 0, KEY_NEED_SEARCH);
	if (IS_ERR(key_ref)) {
		ret = PTR_ERR(key_ref);

		/* Root is permitted to invalidate certain special keys */
		if (capable(CAP_SYS_ADMIN)) {
			key_ref = lookup_user_key(id, 0, 0);
			if (IS_ERR(key_ref))
				goto error;
			if (test_bit(KEY_FLAG_ROOT_CAN_INVAL,
				     &key_ref_to_ptr(key_ref)->flags))
				goto invalidate;
			goto error_put;
		}

		goto error;
	}

invalidate:
	key = key_ref_to_ptr(key_ref);
	ret = 0;
	if (test_bit(KEY_FLAG_KEEP, &key->flags))
		ret = -EPERM;
	else
		key_invalidate(key);
error_put:
	key_ref_put(key_ref);
error:
	kleave(" = %ld", ret);
	return ret;
}

/*
 * Clear the specified keyring, creating an empty process keyring if one of the
 * special keyring IDs is used.
 *
 * The keyring must grant the caller Write permission and not have
 * KEY_FLAG_KEEP set for this to work.  If successful, 0 will be returned.
 */
long keyctl_keyring_clear(key_serial_t ringid)
{
	key_ref_t keyring_ref;
	struct key *keyring;
	long ret;

	keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
	if (IS_ERR(keyring_ref)) {
		ret = PTR_ERR(keyring_ref);

		/* Root is permitted to invalidate certain special keyrings */
		if (capable(CAP_SYS_ADMIN)) {
			keyring_ref = lookup_user_key(ringid, 0, 0);
			if (IS_ERR(keyring_ref))
				goto error;
			if (test_bit(KEY_FLAG_ROOT_CAN_CLEAR,
				     &key_ref_to_ptr(keyring_ref)->flags))
				goto clear;
			goto error_put;
		}

		goto error;
	}

clear:
	keyring = key_ref_to_ptr(keyring_ref);
	if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
		ret = -EPERM;
	else
		ret = keyring_clear(keyring);
error_put:
	key_ref_put(keyring_ref);
error:
	return ret;
}

/*
 * Create a link from a keyring to a key if there's no matching key in the
 * keyring, otherwise replace the link to the matching key with a link to the
 * new key.
 *
 * The key must grant the caller Link permission and the the keyring must grant
 * the caller Write permission.  Furthermore, if an additional link is created,
 * the keyring's quota will be extended.
 *
 * If successful, 0 will be returned.
 */
long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
{
	key_ref_t keyring_ref, key_ref;
	long ret;

	keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
	if (IS_ERR(keyring_ref)) {
		ret = PTR_ERR(keyring_ref);
		goto error;
	}

	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_NEED_LINK);
	if (IS_ERR(key_ref)) {
		ret = PTR_ERR(key_ref);
		goto error2;
	}

	ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));

	key_ref_put(key_ref);
error2:
	key_ref_put(keyring_ref);
error:
	return ret;
}

/*
 * Unlink a key from a keyring.
 *
 * The keyring must grant the caller Write permission for this to work; the key
 * itself need not grant the caller anything.  If the last link to a key is
 * removed then that key will be scheduled for destruction.
 *
 * Keys or keyrings with KEY_FLAG_KEEP set should not be unlinked.
 *
 * If successful, 0 will be returned.
 */
long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
{
	key_ref_t keyring_ref, key_ref;
	struct key *keyring, *key;
	long ret;

	keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_WRITE);
	if (IS_ERR(keyring_ref)) {
		ret = PTR_ERR(keyring_ref);
		goto error;
	}

	key_ref = lookup_user_key(id, KEY_LOOKUP_FOR_UNLINK, 0);
	if (IS_ERR(key_ref)) {
		ret = PTR_ERR(key_ref);
		goto error2;
	}

	keyring = key_ref_to_ptr(keyring_ref);
	key = key_ref_to_ptr(key_ref);
	if (test_bit(KEY_FLAG_KEEP, &keyring->flags) &&
	    test_bit(KEY_FLAG_KEEP, &key->flags))
		ret = -EPERM;
	else
		ret = key_unlink(keyring, key);

	key_ref_put(key_ref);
error2:
	key_ref_put(keyring_ref);
error:
	return ret;
}

/*
 * Move a link to a key from one keyring to another, displacing any matching
 * key from the destination keyring.
 *
 * The key must grant the caller Link permission and both keyrings must grant
 * the caller Write permission.  There must also be a link in the from keyring
 * to the key.  If both keyrings are the same, nothing is done.
 *
 * If successful, 0 will be returned.
 */
long keyctl_keyring_move(key_serial_t id, key_serial_t from_ringid,
			 key_serial_t to_ringid, unsigned int flags)
{
	key_ref_t key_ref, from_ref, to_ref;
	long ret;

	if (flags & ~KEYCTL_MOVE_EXCL)
		return -EINVAL;

	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_NEED_LINK);
	if (IS_ERR(key_ref))
		return PTR_ERR(key_ref);

	from_ref = lookup_user_key(from_ringid, 0, KEY_NEED_WRITE);
	if (IS_ERR(from_ref)) {
		ret = PTR_ERR(from_ref);
		goto error2;
	}

	to_ref = lookup_user_key(to_ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
	if (IS_ERR(to_ref)) {
		ret = PTR_ERR(to_ref);
		goto error3;
	}

	ret = key_move(key_ref_to_ptr(key_ref), key_ref_to_ptr(from_ref),
		       key_ref_to_ptr(to_ref), flags);

	key_ref_put(to_ref);
error3:
	key_ref_put(from_ref);
error2:
	key_ref_put(key_ref);
	return ret;
}

/*
 * Return a description of a key to userspace.
 *
 * The key must grant the caller View permission for this to work.
 *
 * If there's a buffer, we place up to buflen bytes of data into it formatted
 * in the following way:
 *
 *	type;uid;gid;perm;description<NUL>
 *
 * If successful, we return the amount of description available, irrespective
 * of how much we may have copied into the buffer.
 */
long keyctl_describe_key(key_serial_t keyid,
			 char __user *buffer,
			 size_t buflen)
{
	struct key *key, *instkey;
	key_ref_t key_ref;
	char *infobuf;
	long ret;
	int desclen, infolen;

	key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
	if (IS_ERR(key_ref)) {
		/* viewing a key under construction is permitted if we have the
		 * authorisation token handy */
		if (PTR_ERR(key_ref) == -EACCES) {
			instkey = key_get_instantiation_authkey(keyid);
			if (!IS_ERR(instkey)) {
				key_put(instkey);
				key_ref = lookup_user_key(keyid,
							  KEY_LOOKUP_PARTIAL,
							  0);
				if (!IS_ERR(key_ref))
					goto okay;
			}
		}

		ret = PTR_ERR(key_ref);
		goto error;
	}

okay:
	key = key_ref_to_ptr(key_ref);
	desclen = strlen(key->description);

	/* calculate how much information we're going to return */
	ret = -ENOMEM;
	infobuf = kasprintf(GFP_KERNEL,
			    "%s;%d;%d;%08x;",
			    key->type->name,
			    from_kuid_munged(current_user_ns(), key->uid),
			    from_kgid_munged(current_user_ns(), key->gid),
			    key->perm);
	if (!infobuf)
		goto error2;
	infolen = strlen(infobuf);
	ret = infolen + desclen + 1;

	/* consider returning the data */
	if (buffer && buflen >= ret) {
		if (copy_to_user(buffer, infobuf, infolen) != 0 ||
		    copy_to_user(buffer + infolen, key->description,
				 desclen + 1) != 0)
			ret = -EFAULT;
	}

	kfree(infobuf);
error2:
	key_ref_put(key_ref);
error:
	return ret;
}

/*
 * Search the specified keyring and any keyrings it links to for a matching
 * key.  Only keyrings that grant the caller Search permission will be searched
 * (this includes the starting keyring).  Only keys with Search permission can
 * be found.
 *
 * If successful, the found key will be linked to the destination keyring if
 * supplied and the key has Link permission, and the found key ID will be
 * returned.
 */
long keyctl_keyring_search(key_serial_t ringid,
			   const char __user *_type,
			   const char __user *_description,
			   key_serial_t destringid)
{
	struct key_type *ktype;
	key_ref_t keyring_ref, key_ref, dest_ref;
	char type[32], *description;
	long ret;

	/* pull the type and description into kernel space */
	ret = key_get_type_from_user(type, _type, sizeof(type));
	if (ret < 0)
		goto error;

	description = strndup_user(_description, KEY_MAX_DESC_SIZE);
	if (IS_ERR(description)) {
		ret = PTR_ERR(description);
		goto error;
	}

	/* get the keyring at which to begin the search */
	keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_SEARCH);
	if (IS_ERR(keyring_ref)) {
		ret = PTR_ERR(keyring_ref);
		goto error2;
	}

	/* get the destination keyring if specified */
	dest_ref = NULL;
	if (destringid) {
		dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
					   KEY_NEED_WRITE);
		if (IS_ERR(dest_ref)) {
			ret = PTR_ERR(dest_ref);
			goto error3;
		}
	}

	/* find the key type */
	ktype = key_type_lookup(type);
	if (IS_ERR(ktype)) {
		ret = PTR_ERR(ktype);
		goto error4;
	}

	/* do the search */
	key_ref = keyring_search(keyring_ref, ktype, description);
	if (IS_ERR(key_ref)) {
		ret = PTR_ERR(key_ref);

		/* treat lack or presence of a negative key the same */
		if (ret == -EAGAIN)
			ret = -ENOKEY;
		goto error5;
	}

	/* link the resulting key to the destination keyring if we can */
	if (dest_ref) {
		ret = key_permission(key_ref, KEY_NEED_LINK);
		if (ret < 0)
			goto error6;

		ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
		if (ret < 0)
			goto error6;
	}

	ret = key_ref_to_ptr(key_ref)->serial;

error6:
	key_ref_put(key_ref);
error5:
	key_type_put(ktype);
error4:
	key_ref_put(dest_ref);
error3:
	key_ref_put(keyring_ref);
error2:
	kfree(description);
error:
	return ret;
}

/*
 * Read a key's payload.
 *
 * The key must either grant the caller Read permission, or it must grant the
 * caller Search permission when searched for from the process keyrings.
 *
 * If successful, we place up to buflen bytes of data into the buffer, if one
 * is provided, and return the amount of data that is available in the key,
 * irrespective of how much we copied into the buffer.
 */
long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
{
	struct key *key;
	key_ref_t key_ref;
	long ret;

	/* find the key first */
	key_ref = lookup_user_key(keyid, 0, 0);
	if (IS_ERR(key_ref)) {
		ret = -ENOKEY;
		goto error;
	}

	key = key_ref_to_ptr(key_ref);

	ret = key_read_state(key);
	if (ret < 0)
		goto error2; /* Negatively instantiated */

	/* see if we can read it directly */
	ret = key_permission(key_ref, KEY_NEED_READ);
	if (ret == 0)
		goto can_read_key;
	if (ret != -EACCES)
		goto error2;

	/* we can't; see if it's searchable from this process's keyrings
	 * - we automatically take account of the fact that it may be
	 *   dangling off an instantiation key
	 */
	if (!is_key_possessed(key_ref)) {
		ret = -EACCES;
		goto error2;
	}

	/* the key is probably readable - now try to read it */
can_read_key:
	ret = -EOPNOTSUPP;
	if (key->type->read) {
		/* Read the data with the semaphore held (since we might sleep)
		 * to protect against the key being updated or revoked.
		 */
		down_read(&key->sem);
		ret = key_validate(key);
		if (ret == 0)
			ret = key->type->read(key, buffer, buflen);
		up_read(&key->sem);
	}

error2:
	key_put(key);
error:
	return ret;
}

/*
 * Change the ownership of a key
 *
 * The key must grant the caller Setattr permission for this to work, though
 * the key need not be fully instantiated yet.  For the UID to be changed, or
 * for the GID to be changed to a group the caller is not a member of, the
 * caller must have sysadmin capability.  If either uid or gid is -1 then that
 * attribute is not changed.
 *
 * If the UID is to be changed, the new user must have sufficient quota to
 * accept the key.  The quota deduction will be removed from the old user to
 * the new user should the attribute be changed.
 *
 * If successful, 0 will be returned.
 */
long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group)
{
	struct key_user *newowner, *zapowner = NULL;
	struct key *key;
	key_ref_t key_ref;
	long ret;
	kuid_t uid;
	kgid_t gid;

	uid = make_kuid(current_user_ns(), user);
	gid = make_kgid(current_user_ns(), group);
	ret = -EINVAL;
	if ((user != (uid_t) -1) && !uid_valid(uid))
		goto error;
	if ((group != (gid_t) -1) && !gid_valid(gid))
		goto error;

	ret = 0;
	if (user == (uid_t) -1 && group == (gid_t) -1)
		goto error;

	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
				  KEY_NEED_SETATTR);
	if (IS_ERR(key_ref)) {
		ret = PTR_ERR(key_ref);
		goto error;
	}

	key = key_ref_to_ptr(key_ref);

	/* make the changes with the locks held to prevent chown/chown races */
	ret = -EACCES;
	down_write(&key->sem);

	if (!capable(CAP_SYS_ADMIN)) {
		/* only the sysadmin can chown a key to some other UID */
		if (user != (uid_t) -1 && !uid_eq(key->uid, uid))
			goto error_put;

		/* only the sysadmin can set the key's GID to a group other
		 * than one of those that the current process subscribes to */
		if (group != (gid_t) -1 && !gid_eq(gid, key->gid) && !in_group_p(gid))
			goto error_put;
	}

	/* change the UID */
	if (user != (uid_t) -1 && !uid_eq(uid, key->uid)) {
		ret = -ENOMEM;
		newowner = key_user_lookup(uid);
		if (!newowner)
			goto error_put;

		/* transfer the quota burden to the new user */
		if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
			unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
				key_quota_root_maxkeys : key_quota_maxkeys;
			unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
				key_quota_root_maxbytes : key_quota_maxbytes;

			spin_lock(&newowner->lock);
			if (newowner->qnkeys + 1 >= maxkeys ||
			    newowner->qnbytes + key->quotalen >= maxbytes ||
			    newowner->qnbytes + key->quotalen <
			    newowner->qnbytes)
				goto quota_overrun;

			newowner->qnkeys++;
			newowner->qnbytes += key->quotalen;
			spin_unlock(&newowner->lock);

			spin_lock(&key->user->lock);
			key->user->qnkeys--;
			key->user->qnbytes -= key->quotalen;
			spin_unlock(&key->user->lock);
		}

		atomic_dec(&key->user->nkeys);
		atomic_inc(&newowner->nkeys);

		if (key->state != KEY_IS_UNINSTANTIATED) {
			atomic_dec(&key->user->nikeys);
			atomic_inc(&newowner->nikeys);
		}

		zapowner = key->user;
		key->user = newowner;
		key->uid = uid;
	}

	/* change the GID */
	if (group != (gid_t) -1)
		key->gid = gid;

	ret = 0;

error_put:
	up_write(&key->sem);
	key_put(key);
	if (zapowner)
		key_user_put(zapowner);
error:
	return ret;

quota_overrun:
	spin_unlock(&newowner->lock);
	zapowner = newowner;
	ret = -EDQUOT;
	goto error_put;
}

/*
 * Change the permission mask on a key.
 *
 * The key must grant the caller Setattr permission for this to work, though
 * the key need not be fully instantiated yet.  If the caller does not have
 * sysadmin capability, it may only change the permission on keys that it owns.
 */
long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
{
	struct key *key;
	key_ref_t key_ref;
	long ret;

	ret = -EINVAL;
	if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
		goto error;

	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
				  KEY_NEED_SETATTR);
	if (IS_ERR(key_ref)) {
		ret = PTR_ERR(key_ref);
		goto error;
	}

	key = key_ref_to_ptr(key_ref);

	/* make the changes with the locks held to prevent chown/chmod races */
	ret = -EACCES;
	down_write(&key->sem);

	/* if we're not the sysadmin, we can only change a key that we own */
	if (capable(CAP_SYS_ADMIN) || uid_eq(key->uid, current_fsuid())) {
		key->perm = perm;
		ret = 0;
	}

	up_write(&key->sem);
	key_put(key);
error:
	return ret;
}

/*
 * Get the destination keyring for instantiation and check that the caller has
 * Write permission on it.
 */
static long get_instantiation_keyring(key_serial_t ringid,
				      struct request_key_auth *rka,
				      struct key **_dest_keyring)
{
	key_ref_t dkref;

	*_dest_keyring = NULL;

	/* just return a NULL pointer if we weren't asked to make a link */
	if (ringid == 0)
		return 0;

	/* if a specific keyring is nominated by ID, then use that */
	if (ringid > 0) {
		dkref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
		if (IS_ERR(dkref))
			return PTR_ERR(dkref);
		*_dest_keyring = key_ref_to_ptr(dkref);
		return 0;
	}

	if (ringid == KEY_SPEC_REQKEY_AUTH_KEY)
		return -EINVAL;

	/* otherwise specify the destination keyring recorded in the
	 * authorisation key (any KEY_SPEC_*_KEYRING) */
	if (ringid >= KEY_SPEC_REQUESTOR_KEYRING) {
		*_dest_keyring = key_get(rka->dest_keyring);
		return 0;
	}

	return -ENOKEY;
}

/*
 * Change the request_key authorisation key on the current process.
 */
static int keyctl_change_reqkey_auth(struct key *key)
{
	struct cred *new;

	new = prepare_creds();
	if (!new)
		return -ENOMEM;

	key_put(new->request_key_auth);
	new->request_key_auth = key_get(key);

	return commit_creds(new);
}

/*
 * Instantiate a key with the specified payload and link the key into the
 * destination keyring if one is given.
 *
 * The caller must have the appropriate instantiation permit set for this to
 * work (see keyctl_assume_authority).  No other permissions are required.
 *
 * If successful, 0 will be returned.
 */
long keyctl_instantiate_key_common(key_serial_t id,
				   struct iov_iter *from,
				   key_serial_t ringid)
{
	const struct cred *cred = current_cred();
	struct request_key_auth *rka;
	struct key *instkey, *dest_keyring;
	size_t plen = from ? iov_iter_count(from) : 0;
	void *payload;
	long ret;

	kenter("%d,,%zu,%d", id, plen, ringid);

	if (!plen)
		from = NULL;

	ret = -EINVAL;
	if (plen > 1024 * 1024 - 1)
		goto error;

	/* the appropriate instantiation authorisation key must have been
	 * assumed before calling this */
	ret = -EPERM;
	instkey = cred->request_key_auth;
	if (!instkey)
		goto error;

	rka = instkey->payload.data[0];
	if (rka->target_key->serial != id)
		goto error;

	/* pull the payload in if one was supplied */
	payload = NULL;

	if (from) {
		ret = -ENOMEM;
		payload = kvmalloc(plen, GFP_KERNEL);
		if (!payload)
			goto error;

		ret = -EFAULT;
		if (!copy_from_iter_full(payload, plen, from))
			goto error2;
	}

	/* find the destination keyring amongst those belonging to the
	 * requesting task */
	ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
	if (ret < 0)
		goto error2;

	/* instantiate the key and link it into a keyring */
	ret = key_instantiate_and_link(rka->target_key, payload, plen,
				       dest_keyring, instkey);

	key_put(dest_keyring);

	/* discard the assumed authority if it's just been disabled by
	 * instantiation of the key */
	if (ret == 0)
		keyctl_change_reqkey_auth(NULL);

error2:
	if (payload) {
		memzero_explicit(payload, plen);
		kvfree(payload);
	}
error:
	return ret;
}

/*
 * Instantiate a key with the specified payload and link the key into the
 * destination keyring if one is given.
 *
 * The caller must have the appropriate instantiation permit set for this to
 * work (see keyctl_assume_authority).  No other permissions are required.
 *
 * If successful, 0 will be returned.
 */
long keyctl_instantiate_key(key_serial_t id,
			    const void __user *_payload,
			    size_t plen,
			    key_serial_t ringid)
{
	if (_payload && plen) {
		struct iovec iov;
		struct iov_iter from;
		int ret;

		ret = import_single_range(WRITE, (void __user *)_payload, plen,
					  &iov, &from);
		if (unlikely(ret))
			return ret;

		return keyctl_instantiate_key_common(id, &from, ringid);
	}

	return keyctl_instantiate_key_common(id, NULL, ringid);
}

/*
 * Instantiate a key with the specified multipart payload and link the key into
 * the destination keyring if one is given.
 *
 * The caller must have the appropriate instantiation permit set for this to
 * work (see keyctl_assume_authority).  No other permissions are required.
 *
 * If successful, 0 will be returned.
 */
long keyctl_instantiate_key_iov(key_serial_t id,
				const struct iovec __user *_payload_iov,
				unsigned ioc,
				key_serial_t ringid)
{
	struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
	struct iov_iter from;
	long ret;

	if (!_payload_iov)
		ioc = 0;

	ret = import_iovec(WRITE, _payload_iov, ioc,
				    ARRAY_SIZE(iovstack), &iov, &from);
	if (ret < 0)
		return ret;
	ret = keyctl_instantiate_key_common(id, &from, ringid);
	kfree(iov);
	return ret;
}

/*
 * Negatively instantiate the key with the given timeout (in seconds) and link
 * the key into the destination keyring if one is given.
 *
 * The caller must have the appropriate instantiation permit set for this to
 * work (see keyctl_assume_authority).  No other permissions are required.
 *
 * The key and any links to the key will be automatically garbage collected
 * after the timeout expires.
 *
 * Negative keys are used to rate limit repeated request_key() calls by causing
 * them to return -ENOKEY until the negative key expires.
 *
 * If successful, 0 will be returned.
 */
long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
{
	return keyctl_reject_key(id, timeout, ENOKEY, ringid);
}

/*
 * Negatively instantiate the key with the given timeout (in seconds) and error
 * code and link the key into the destination keyring if one is given.
 *
 * The caller must have the appropriate instantiation permit set for this to
 * work (see keyctl_assume_authority).  No other permissions are required.
 *
 * The key and any links to the key will be automatically garbage collected
 * after the timeout expires.
 *
 * Negative keys are used to rate limit repeated request_key() calls by causing
 * them to return the specified error code until the negative key expires.
 *
 * If successful, 0 will be returned.
 */
long keyctl_reject_key(key_serial_t id, unsigned timeout, unsigned error,
		       key_serial_t ringid)
{
	const struct cred *cred = current_cred();
	struct request_key_auth *rka;
	struct key *instkey, *dest_keyring;
	long ret;

	kenter("%d,%u,%u,%d", id, timeout, error, ringid);

	/* must be a valid error code and mustn't be a kernel special */
	if (error <= 0 ||
	    error >= MAX_ERRNO ||
	    error == ERESTARTSYS ||
	    error == ERESTARTNOINTR ||
	    error == ERESTARTNOHAND ||
	    error == ERESTART_RESTARTBLOCK)
		return -EINVAL;

	/* the appropriate instantiation authorisation key must have been
	 * assumed before calling this */
	ret = -EPERM;
	instkey = cred->request_key_auth;
	if (!instkey)
		goto error;

	rka = instkey->payload.data[0];
	if (rka->target_key->serial != id)
		goto error;

	/* find the destination keyring if present (which must also be
	 * writable) */
	ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
	if (ret < 0)
		goto error;

	/* instantiate the key and link it into a keyring */
	ret = key_reject_and_link(rka->target_key, timeout, error,
				  dest_keyring, instkey);

	key_put(dest_keyring);

	/* discard the assumed authority if it's just been disabled by
	 * instantiation of the key */
	if (ret == 0)
		keyctl_change_reqkey_auth(NULL);

error:
	return ret;
}

/*
 * Read or set the default keyring in which request_key() will cache keys and
 * return the old setting.
 *
 * If a thread or process keyring is specified then it will be created if it
 * doesn't yet exist.  The old setting will be returned if successful.
 */
long keyctl_set_reqkey_keyring(int reqkey_defl)
{
	struct cred *new;
	int ret, old_setting;

	old_setting = current_cred_xxx(jit_keyring);

	if (reqkey_defl == KEY_REQKEY_DEFL_NO_CHANGE)
		return old_setting;

	new = prepare_creds();
	if (!new)
		return -ENOMEM;

	switch (reqkey_defl) {
	case KEY_REQKEY_DEFL_THREAD_KEYRING:
		ret = install_thread_keyring_to_cred(new);
		if (ret < 0)
			goto error;
		goto set;

	case KEY_REQKEY_DEFL_PROCESS_KEYRING:
		ret = install_process_keyring_to_cred(new);
		if (ret < 0)
			goto error;
		goto set;

	case KEY_REQKEY_DEFL_DEFAULT:
	case KEY_REQKEY_DEFL_SESSION_KEYRING:
	case KEY_REQKEY_DEFL_USER_KEYRING:
	case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
	case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
		goto set;

	case KEY_REQKEY_DEFL_NO_CHANGE:
	case KEY_REQKEY_DEFL_GROUP_KEYRING:
	default:
		ret = -EINVAL;
		goto error;
	}

set:
	new->jit_keyring = reqkey_defl;
	commit_creds(new);
	return old_setting;
error:
	abort_creds(new);
	return ret;
}

/*
 * Set or clear the timeout on a key.
 *
 * Either the key must grant the caller Setattr permission or else the caller
 * must hold an instantiation authorisation token for the key.
 *
 * The timeout is either 0 to clear the timeout, or a number of seconds from
 * the current time.  The key and any links to the key will be automatically
 * garbage collected after the timeout expires.
 *
 * Keys with KEY_FLAG_KEEP set should not be timed out.
 *
 * If successful, 0 is returned.
 */
long keyctl_set_timeout(key_serial_t id, unsigned timeout)
{
	struct key *key, *instkey;
	key_ref_t key_ref;
	long ret;

	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
				  KEY_NEED_SETATTR);
	if (IS_ERR(key_ref)) {
		/* setting the timeout on a key under construction is permitted
		 * if we have the authorisation token handy */
		if (PTR_ERR(key_ref) == -EACCES) {
			instkey = key_get_instantiation_authkey(id);
			if (!IS_ERR(instkey)) {
				key_put(instkey);
				key_ref = lookup_user_key(id,
							  KEY_LOOKUP_PARTIAL,
							  0);
				if (!IS_ERR(key_ref))
					goto okay;
			}
		}

		ret = PTR_ERR(key_ref);
		goto error;
	}

okay:
	key = key_ref_to_ptr(key_ref);
	ret = 0;
	if (test_bit(KEY_FLAG_KEEP, &key->flags))
		ret = -EPERM;
	else
		key_set_timeout(key, timeout);
	key_put(key);

error:
	return ret;
}

/*
 * Assume (or clear) the authority to instantiate the specified key.
 *
 * This sets the authoritative token currently in force for key instantiation.
 * This must be done for a key to be instantiated.  It has the effect of making
 * available all the keys from the caller of the request_key() that created a
 * key to request_key() calls made by the caller of this function.
 *
 * The caller must have the instantiation key in their process keyrings with a
 * Search permission grant available to the caller.
 *
 * If the ID given is 0, then the setting will be cleared and 0 returned.
 *
 * If the ID given has a matching an authorisation key, then that key will be
 * set and its ID will be returned.  The authorisation key can be read to get
 * the callout information passed to request_key().
 */
long keyctl_assume_authority(key_serial_t id)
{
	struct key *authkey;
	long ret;

	/* special key IDs aren't permitted */
	ret = -EINVAL;
	if (id < 0)
		goto error;

	/* we divest ourselves of authority if given an ID of 0 */
	if (id == 0) {
		ret = keyctl_change_reqkey_auth(NULL);
		goto error;
	}

	/* attempt to assume the authority temporarily granted to us whilst we
	 * instantiate the specified key
	 * - the authorisation key must be in the current task's keyrings
	 *   somewhere
	 */
	authkey = key_get_instantiation_authkey(id);
	if (IS_ERR(authkey)) {
		ret = PTR_ERR(authkey);
		goto error;
	}

	ret = keyctl_change_reqkey_auth(authkey);
	if (ret == 0)
		ret = authkey->serial;
	key_put(authkey);
error:
	return ret;
}

/*
 * Get a key's the LSM security label.
 *
 * The key must grant the caller View permission for this to work.
 *
 * If there's a buffer, then up to buflen bytes of data will be placed into it.
 *
 * If successful, the amount of information available will be returned,
 * irrespective of how much was copied (including the terminal NUL).
 */
long keyctl_get_security(key_serial_t keyid,
			 char __user *buffer,
			 size_t buflen)
{
	struct key *key, *instkey;
	key_ref_t key_ref;
	char *context;
	long ret;

	key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
	if (IS_ERR(key_ref)) {
		if (PTR_ERR(key_ref) != -EACCES)
			return PTR_ERR(key_ref);

		/* viewing a key under construction is also permitted if we
		 * have the authorisation token handy */
		instkey = key_get_instantiation_authkey(keyid);
		if (IS_ERR(instkey))
			return PTR_ERR(instkey);
		key_put(instkey);

		key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, 0);
		if (IS_ERR(key_ref))
			return PTR_ERR(key_ref);
	}

	key = key_ref_to_ptr(key_ref);
	ret = security_key_getsecurity(key, &context);
	if (ret == 0) {
		/* if no information was returned, give userspace an empty
		 * string */
		ret = 1;
		if (buffer && buflen > 0 &&
		    copy_to_user(buffer, "", 1) != 0)
			ret = -EFAULT;
	} else if (ret > 0) {
		/* return as much data as there's room for */
		if (buffer && buflen > 0) {
			if (buflen > ret)
				buflen = ret;

			if (copy_to_user(buffer, context, buflen) != 0)
				ret = -EFAULT;
		}

		kfree(context);
	}

	key_ref_put(key_ref);
	return ret;
}

/*
 * Attempt to install the calling process's session keyring on the process's
 * parent process.
 *
 * The keyring must exist and must grant the caller LINK permission, and the
 * parent process must be single-threaded and must have the same effective
 * ownership as this process and mustn't be SUID/SGID.
 *
 * The keyring will be emplaced on the parent when it next resumes userspace.
 *
 * If successful, 0 will be returned.
 */
long keyctl_session_to_parent(void)
{
	struct task_struct *me, *parent;
	const struct cred *mycred, *pcred;
	struct callback_head *newwork, *oldwork;
	key_ref_t keyring_r;
	struct cred *cred;
	int ret;

	keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_NEED_LINK);
	if (IS_ERR(keyring_r))
		return PTR_ERR(keyring_r);

	ret = -ENOMEM;

	/* our parent is going to need a new cred struct, a new tgcred struct
	 * and new security data, so we allocate them here to prevent ENOMEM in
	 * our parent */
	cred = cred_alloc_blank();
	if (!cred)
		goto error_keyring;
	newwork = &cred->rcu;

	cred->session_keyring = key_ref_to_ptr(keyring_r);
	keyring_r = NULL;
	init_task_work(newwork, key_change_session_keyring);

	me = current;
	rcu_read_lock();
	write_lock_irq(&tasklist_lock);

	ret = -EPERM;
	oldwork = NULL;
	parent = rcu_dereference_protected(me->real_parent,
					   lockdep_is_held(&tasklist_lock));

	/* the parent mustn't be init and mustn't be a kernel thread */
	if (parent->pid <= 1 || !parent->mm)
		goto unlock;

	/* the parent must be single threaded */
	if (!thread_group_empty(parent))
		goto unlock;

	/* the parent and the child must have different session keyrings or
	 * there's no point */
	mycred = current_cred();
	pcred = __task_cred(parent);
	if (mycred == pcred ||
	    mycred->session_keyring == pcred->session_keyring) {
		ret = 0;
		goto unlock;
	}

	/* the parent must have the same effective ownership and mustn't be
	 * SUID/SGID */
	if (!uid_eq(pcred->uid,	 mycred->euid) ||
	    !uid_eq(pcred->euid, mycred->euid) ||
	    !uid_eq(pcred->suid, mycred->euid) ||
	    !gid_eq(pcred->gid,	 mycred->egid) ||
	    !gid_eq(pcred->egid, mycred->egid) ||
	    !gid_eq(pcred->sgid, mycred->egid))
		goto unlock;

	/* the keyrings must have the same UID */
	if ((pcred->session_keyring &&
	     !uid_eq(pcred->session_keyring->uid, mycred->euid)) ||
	    !uid_eq(mycred->session_keyring->uid, mycred->euid))
		goto unlock;

	/* cancel an already pending keyring replacement */
	oldwork = task_work_cancel(parent, key_change_session_keyring);

	/* the replacement session keyring is applied just prior to userspace
	 * restarting */
	ret = task_work_add(parent, newwork, true);
	if (!ret)
		newwork = NULL;
unlock:
	write_unlock_irq(&tasklist_lock);
	rcu_read_unlock();
	if (oldwork)
		put_cred(container_of(oldwork, struct cred, rcu));
	if (newwork)
		put_cred(cred);
	return ret;

error_keyring:
	key_ref_put(keyring_r);
	return ret;
}

/*
 * Apply a restriction to a given keyring.
 *
 * The caller must have Setattr permission to change keyring restrictions.
 *
 * The requested type name may be a NULL pointer to reject all attempts
 * to link to the keyring.  In this case, _restriction must also be NULL.
 * Otherwise, both _type and _restriction must be non-NULL.
 *
 * Returns 0 if successful.
 */
long keyctl_restrict_keyring(key_serial_t id, const char __user *_type,
			     const char __user *_restriction)
{
	key_ref_t key_ref;
	char type[32];
	char *restriction = NULL;
	long ret;

	key_ref = lookup_user_key(id, 0, KEY_NEED_SETATTR);
	if (IS_ERR(key_ref))
		return PTR_ERR(key_ref);

	ret = -EINVAL;
	if (_type) {
		if (!_restriction)
			goto error;

		ret = key_get_type_from_user(type, _type, sizeof(type));
		if (ret < 0)
			goto error;

		restriction = strndup_user(_restriction, PAGE_SIZE);
		if (IS_ERR(restriction)) {
			ret = PTR_ERR(restriction);
			goto error;
		}
	} else {
		if (_restriction)
			goto error;
	}

	ret = keyring_restrict(key_ref, _type ? type : NULL, restriction);
	kfree(restriction);
error:
	key_ref_put(key_ref);
	return ret;
}

/*
 * Get keyrings subsystem capabilities.
 */
long keyctl_capabilities(unsigned char __user *_buffer, size_t buflen)
{
	size_t size = buflen;

	if (size > 0) {
		if (size > sizeof(keyrings_capabilities))
			size = sizeof(keyrings_capabilities);
		if (copy_to_user(_buffer, keyrings_capabilities, size) != 0)
			return -EFAULT;
		if (size < buflen &&
		    clear_user(_buffer + size, buflen - size) != 0)
			return -EFAULT;
	}

	return sizeof(keyrings_capabilities);
}

/*
 * The key control system call
 */
SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
		unsigned long, arg4, unsigned long, arg5)
{
	switch (option) {
	case KEYCTL_GET_KEYRING_ID:
		return keyctl_get_keyring_ID((key_serial_t) arg2,
					     (int) arg3);

	case KEYCTL_JOIN_SESSION_KEYRING:
		return keyctl_join_session_keyring((const char __user *) arg2);

	case KEYCTL_UPDATE:
		return keyctl_update_key((key_serial_t) arg2,
					 (const void __user *) arg3,
					 (size_t) arg4);

	case KEYCTL_REVOKE:
		return keyctl_revoke_key((key_serial_t) arg2);

	case KEYCTL_DESCRIBE:
		return keyctl_describe_key((key_serial_t) arg2,
					   (char __user *) arg3,
					   (unsigned) arg4);

	case KEYCTL_CLEAR:
		return keyctl_keyring_clear((key_serial_t) arg2);

	case KEYCTL_LINK:
		return keyctl_keyring_link((key_serial_t) arg2,
					   (key_serial_t) arg3);

	case KEYCTL_UNLINK:
		return keyctl_keyring_unlink((key_serial_t) arg2,
					     (key_serial_t) arg3);

	case KEYCTL_SEARCH:
		return keyctl_keyring_search((key_serial_t) arg2,
					     (const char __user *) arg3,
					     (const char __user *) arg4,
					     (key_serial_t) arg5);

	case KEYCTL_READ:
		return keyctl_read_key((key_serial_t) arg2,
				       (char __user *) arg3,
				       (size_t) arg4);

	case KEYCTL_CHOWN:
		return keyctl_chown_key((key_serial_t) arg2,
					(uid_t) arg3,
					(gid_t) arg4);

	case KEYCTL_SETPERM:
		return keyctl_setperm_key((key_serial_t) arg2,
					  (key_perm_t) arg3);

	case KEYCTL_INSTANTIATE:
		return keyctl_instantiate_key((key_serial_t) arg2,
					      (const void __user *) arg3,
					      (size_t) arg4,
					      (key_serial_t) arg5);

	case KEYCTL_NEGATE:
		return keyctl_negate_key((key_serial_t) arg2,
					 (unsigned) arg3,
					 (key_serial_t) arg4);

	case KEYCTL_SET_REQKEY_KEYRING:
		return keyctl_set_reqkey_keyring(arg2);

	case KEYCTL_SET_TIMEOUT:
		return keyctl_set_timeout((key_serial_t) arg2,
					  (unsigned) arg3);

	case KEYCTL_ASSUME_AUTHORITY:
		return keyctl_assume_authority((key_serial_t) arg2);

	case KEYCTL_GET_SECURITY:
		return keyctl_get_security((key_serial_t) arg2,
					   (char __user *) arg3,
					   (size_t) arg4);

	case KEYCTL_SESSION_TO_PARENT:
		return keyctl_session_to_parent();

	case KEYCTL_REJECT:
		return keyctl_reject_key((key_serial_t) arg2,
					 (unsigned) arg3,
					 (unsigned) arg4,
					 (key_serial_t) arg5);

	case KEYCTL_INSTANTIATE_IOV:
		return keyctl_instantiate_key_iov(
			(key_serial_t) arg2,
			(const struct iovec __user *) arg3,
			(unsigned) arg4,
			(key_serial_t) arg5);

	case KEYCTL_INVALIDATE:
		return keyctl_invalidate_key((key_serial_t) arg2);

	case KEYCTL_GET_PERSISTENT:
		return keyctl_get_persistent((uid_t)arg2, (key_serial_t)arg3);

	case KEYCTL_DH_COMPUTE:
		return keyctl_dh_compute((struct keyctl_dh_params __user *) arg2,
					 (char __user *) arg3, (size_t) arg4,
					 (struct keyctl_kdf_params __user *) arg5);

	case KEYCTL_RESTRICT_KEYRING:
		return keyctl_restrict_keyring((key_serial_t) arg2,
					       (const char __user *) arg3,
					       (const char __user *) arg4);

	case KEYCTL_PKEY_QUERY:
		if (arg3 != 0)
			return -EINVAL;
		return keyctl_pkey_query((key_serial_t)arg2,
					 (const char __user *)arg4,
					 (struct keyctl_pkey_query __user *)arg5);

	case KEYCTL_PKEY_ENCRYPT:
	case KEYCTL_PKEY_DECRYPT:
	case KEYCTL_PKEY_SIGN:
		return keyctl_pkey_e_d_s(
			option,
			(const struct keyctl_pkey_params __user *)arg2,
			(const char __user *)arg3,
			(const void __user *)arg4,
			(void __user *)arg5);

	case KEYCTL_PKEY_VERIFY:
		return keyctl_pkey_verify(
			(const struct keyctl_pkey_params __user *)arg2,
			(const char __user *)arg3,
			(const void __user *)arg4,
			(const void __user *)arg5);

	case KEYCTL_MOVE:
		return keyctl_keyring_move((key_serial_t)arg2,
					   (key_serial_t)arg3,
					   (key_serial_t)arg4,
					   (unsigned int)arg5);

	case KEYCTL_CAPABILITIES:
		return keyctl_capabilities((unsigned char __user *)arg2, (size_t)arg3);

	default:
		return -EOPNOTSUPP;
	}
}