summaryrefslogtreecommitdiff
path: root/ipc/kdbus/connection.c
blob: ef63d6533273069cfbb878ac9236cced30ef6416 (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
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
/*
 * Copyright (C) 2013-2015 Kay Sievers
 * Copyright (C) 2013-2015 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 * Copyright (C) 2013-2015 Daniel Mack <daniel@zonque.org>
 * Copyright (C) 2013-2015 David Herrmann <dh.herrmann@gmail.com>
 * Copyright (C) 2013-2015 Linux Foundation
 * Copyright (C) 2014-2015 Djalal Harouni <tixxdz@opendz.org>
 *
 * kdbus is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the
 * Free Software Foundation; either version 2.1 of the License, or (at
 * your option) any later version.
 */

#include <linux/audit.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/fs_struct.h>
#include <linux/hashtable.h>
#include <linux/idr.h>
#include <linux/init.h>
#include <linux/math64.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/path.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/shmem_fs.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/syscalls.h>
#include <linux/uio.h>

#include "bus.h"
#include "connection.h"
#include "endpoint.h"
#include "handle.h"
#include "match.h"
#include "message.h"
#include "metadata.h"
#include "names.h"
#include "domain.h"
#include "item.h"
#include "notify.h"
#include "policy.h"
#include "pool.h"
#include "reply.h"
#include "util.h"
#include "queue.h"

#define KDBUS_CONN_ACTIVE_BIAS	(INT_MIN + 2)
#define KDBUS_CONN_ACTIVE_NEW	(INT_MIN + 1)

static struct kdbus_conn *kdbus_conn_new(struct kdbus_ep *ep,
					 struct file *file,
					 struct kdbus_cmd_hello *hello,
					 const char *name,
					 const struct kdbus_creds *creds,
					 const struct kdbus_pids *pids,
					 const char *seclabel,
					 const char *conn_description)
{
#ifdef CONFIG_DEBUG_LOCK_ALLOC
	static struct lock_class_key __key;
#endif
	struct kdbus_pool_slice *slice = NULL;
	struct kdbus_bus *bus = ep->bus;
	struct kdbus_conn *conn;
	u64 attach_flags_send;
	u64 attach_flags_recv;
	u64 items_size = 0;
	bool is_policy_holder;
	bool is_activator;
	bool is_monitor;
	bool privileged;
	bool owner;
	struct kvec kvec;
	int ret;

	struct {
		u64 size;
		u64 type;
		struct kdbus_bloom_parameter bloom;
	} bloom_item;

	privileged = kdbus_ep_is_privileged(ep, file);
	owner = kdbus_ep_is_owner(ep, file);

	is_monitor = hello->flags & KDBUS_HELLO_MONITOR;
	is_activator = hello->flags & KDBUS_HELLO_ACTIVATOR;
	is_policy_holder = hello->flags & KDBUS_HELLO_POLICY_HOLDER;

	if (!hello->pool_size || !IS_ALIGNED(hello->pool_size, PAGE_SIZE))
		return ERR_PTR(-EINVAL);
	if (is_monitor + is_activator + is_policy_holder > 1)
		return ERR_PTR(-EINVAL);
	if (name && !is_activator && !is_policy_holder)
		return ERR_PTR(-EINVAL);
	if (!name && (is_activator || is_policy_holder))
		return ERR_PTR(-EINVAL);
	if (name && !kdbus_name_is_valid(name, true))
		return ERR_PTR(-EINVAL);
	if (is_monitor && ep->user)
		return ERR_PTR(-EOPNOTSUPP);
	if (!owner && (is_activator || is_policy_holder || is_monitor))
		return ERR_PTR(-EPERM);
	if (!owner && (creds || pids || seclabel))
		return ERR_PTR(-EPERM);

	ret = kdbus_sanitize_attach_flags(hello->attach_flags_send,
					  &attach_flags_send);
	if (ret < 0)
		return ERR_PTR(ret);

	ret = kdbus_sanitize_attach_flags(hello->attach_flags_recv,
					  &attach_flags_recv);
	if (ret < 0)
		return ERR_PTR(ret);

	conn = kzalloc(sizeof(*conn), GFP_KERNEL);
	if (!conn)
		return ERR_PTR(-ENOMEM);

	kref_init(&conn->kref);
	atomic_set(&conn->active, KDBUS_CONN_ACTIVE_NEW);
#ifdef CONFIG_DEBUG_LOCK_ALLOC
	lockdep_init_map(&conn->dep_map, "s_active", &__key, 0);
#endif
	mutex_init(&conn->lock);
	INIT_LIST_HEAD(&conn->names_list);
	INIT_LIST_HEAD(&conn->reply_list);
	atomic_set(&conn->request_count, 0);
	atomic_set(&conn->lost_count, 0);
	INIT_DELAYED_WORK(&conn->work, kdbus_reply_list_scan_work);
	conn->cred = get_cred(file->f_cred);
	conn->pid = get_pid(task_pid(current));
	get_fs_root(current->fs, &conn->root_path);
	init_waitqueue_head(&conn->wait);
	kdbus_queue_init(&conn->queue);
	conn->privileged = privileged;
	conn->owner = owner;
	conn->ep = kdbus_ep_ref(ep);
	conn->id = atomic64_inc_return(&bus->domain->last_id);
	conn->flags = hello->flags;
	atomic64_set(&conn->attach_flags_send, attach_flags_send);
	atomic64_set(&conn->attach_flags_recv, attach_flags_recv);
	INIT_LIST_HEAD(&conn->monitor_entry);

	if (conn_description) {
		conn->description = kstrdup(conn_description, GFP_KERNEL);
		if (!conn->description) {
			ret = -ENOMEM;
			goto exit_unref;
		}
	}

	conn->pool = kdbus_pool_new(conn->description, hello->pool_size);
	if (IS_ERR(conn->pool)) {
		ret = PTR_ERR(conn->pool);
		conn->pool = NULL;
		goto exit_unref;
	}

	conn->match_db = kdbus_match_db_new();
	if (IS_ERR(conn->match_db)) {
		ret = PTR_ERR(conn->match_db);
		conn->match_db = NULL;
		goto exit_unref;
	}

	/* return properties of this connection to the caller */
	hello->bus_flags = bus->bus_flags;
	hello->id = conn->id;

	BUILD_BUG_ON(sizeof(bus->id128) != sizeof(hello->id128));
	memcpy(hello->id128, bus->id128, sizeof(hello->id128));

	/* privileged processes can impersonate somebody else */
	if (creds || pids || seclabel) {
		conn->meta_fake = kdbus_meta_fake_new();
		if (IS_ERR(conn->meta_fake)) {
			ret = PTR_ERR(conn->meta_fake);
			conn->meta_fake = NULL;
			goto exit_unref;
		}

		ret = kdbus_meta_fake_collect(conn->meta_fake,
					      creds, pids, seclabel);
		if (ret < 0)
			goto exit_unref;
	} else {
		conn->meta_proc = kdbus_meta_proc_new();
		if (IS_ERR(conn->meta_proc)) {
			ret = PTR_ERR(conn->meta_proc);
			conn->meta_proc = NULL;
			goto exit_unref;
		}

		ret = kdbus_meta_proc_collect(conn->meta_proc,
					      KDBUS_ATTACH_CREDS |
					      KDBUS_ATTACH_PIDS |
					      KDBUS_ATTACH_AUXGROUPS |
					      KDBUS_ATTACH_TID_COMM |
					      KDBUS_ATTACH_PID_COMM |
					      KDBUS_ATTACH_EXE |
					      KDBUS_ATTACH_CMDLINE |
					      KDBUS_ATTACH_CGROUP |
					      KDBUS_ATTACH_CAPS |
					      KDBUS_ATTACH_SECLABEL |
					      KDBUS_ATTACH_AUDIT);
		if (ret < 0)
			goto exit_unref;
	}

	/*
	 * Account the connection against the current user (UID), or for
	 * custom endpoints use the anonymous user assigned to the endpoint.
	 * Note that limits are always accounted against the real UID, not
	 * the effective UID (cred->user always points to the accounting of
	 * cred->uid, not cred->euid).
	 * In case the caller is privileged, we allow changing the accounting
	 * to the faked user.
	 */
	if (ep->user) {
		conn->user = kdbus_user_ref(ep->user);
	} else {
		kuid_t uid;

		if (conn->meta_fake && uid_valid(conn->meta_fake->uid) &&
		    conn->privileged)
			uid = conn->meta_fake->uid;
		else
			uid = conn->cred->uid;

		conn->user = kdbus_user_lookup(ep->bus->domain, uid);
		if (IS_ERR(conn->user)) {
			ret = PTR_ERR(conn->user);
			conn->user = NULL;
			goto exit_unref;
		}
	}

	if (atomic_inc_return(&conn->user->connections) > KDBUS_USER_MAX_CONN) {
		/* decremented by destructor as conn->user is valid */
		ret = -EMFILE;
		goto exit_unref;
	}

	bloom_item.size = sizeof(bloom_item);
	bloom_item.type = KDBUS_ITEM_BLOOM_PARAMETER;
	bloom_item.bloom = bus->bloom;
	kdbus_kvec_set(&kvec, &bloom_item, bloom_item.size, &items_size);

	slice = kdbus_pool_slice_alloc(conn->pool, items_size, false);
	if (IS_ERR(slice)) {
		ret = PTR_ERR(slice);
		slice = NULL;
		goto exit_unref;
	}

	ret = kdbus_pool_slice_copy_kvec(slice, 0, &kvec, 1, items_size);
	if (ret < 0)
		goto exit_unref;

	kdbus_pool_slice_publish(slice, &hello->offset, &hello->items_size);
	kdbus_pool_slice_release(slice);

	return conn;

exit_unref:
	kdbus_pool_slice_release(slice);
	kdbus_conn_unref(conn);
	return ERR_PTR(ret);
}

static void __kdbus_conn_free(struct kref *kref)
{
	struct kdbus_conn *conn = container_of(kref, struct kdbus_conn, kref);

	WARN_ON(kdbus_conn_active(conn));
	WARN_ON(delayed_work_pending(&conn->work));
	WARN_ON(!list_empty(&conn->queue.msg_list));
	WARN_ON(!list_empty(&conn->names_list));
	WARN_ON(!list_empty(&conn->reply_list));

	if (conn->user) {
		atomic_dec(&conn->user->connections);
		kdbus_user_unref(conn->user);
	}

	kdbus_meta_fake_free(conn->meta_fake);
	kdbus_meta_proc_unref(conn->meta_proc);
	kdbus_match_db_free(conn->match_db);
	kdbus_pool_free(conn->pool);
	kdbus_ep_unref(conn->ep);
	path_put(&conn->root_path);
	put_pid(conn->pid);
	put_cred(conn->cred);
	kfree(conn->description);
	kfree(conn->quota);
	kfree(conn);
}

/**
 * kdbus_conn_ref() - take a connection reference
 * @conn:		Connection, may be %NULL
 *
 * Return: the connection itself
 */
struct kdbus_conn *kdbus_conn_ref(struct kdbus_conn *conn)
{
	if (conn)
		kref_get(&conn->kref);
	return conn;
}

/**
 * kdbus_conn_unref() - drop a connection reference
 * @conn:		Connection (may be NULL)
 *
 * When the last reference is dropped, the connection's internal structure
 * is freed.
 *
 * Return: NULL
 */
struct kdbus_conn *kdbus_conn_unref(struct kdbus_conn *conn)
{
	if (conn)
		kref_put(&conn->kref, __kdbus_conn_free);
	return NULL;
}

/**
 * kdbus_conn_active() - connection is not disconnected
 * @conn:		Connection to check
 *
 * Return true if the connection was not disconnected, yet. Note that a
 * connection might be disconnected asynchronously, unless you hold the
 * connection lock. If that's not suitable for you, see kdbus_conn_acquire() to
 * suppress connection shutdown for a short period.
 *
 * Return: true if the connection is still active
 */
bool kdbus_conn_active(const struct kdbus_conn *conn)
{
	return atomic_read(&conn->active) >= 0;
}

/**
 * kdbus_conn_acquire() - acquire an active connection reference
 * @conn:		Connection
 *
 * Users can close a connection via KDBUS_BYEBYE (or by destroying the
 * endpoint/bus/...) at any time. Whenever this happens, we should deny any
 * user-visible action on this connection and signal ECONNRESET instead.
 * To avoid testing for connection availability everytime you take the
 * connection-lock, you can acquire a connection for short periods.
 *
 * By calling kdbus_conn_acquire(), you gain an "active reference" to the
 * connection. You must also hold a regular reference at any time! As long as
 * you hold the active-ref, the connection will not be shut down. However, if
 * the connection was shut down, you can never acquire an active-ref again.
 *
 * kdbus_conn_disconnect() disables the connection and then waits for all active
 * references to be dropped. It will also wake up any pending operation.
 * However, you must not sleep for an indefinite period while holding an
 * active-reference. Otherwise, kdbus_conn_disconnect() might stall. If you need
 * to sleep for an indefinite period, either release the reference and try to
 * acquire it again after waking up, or make kdbus_conn_disconnect() wake up
 * your wait-queue.
 *
 * Return: 0 on success, negative error code on failure.
 */
int kdbus_conn_acquire(struct kdbus_conn *conn)
{
	if (!atomic_inc_unless_negative(&conn->active))
		return -ECONNRESET;

#ifdef CONFIG_DEBUG_LOCK_ALLOC
	rwsem_acquire_read(&conn->dep_map, 0, 1, _RET_IP_);
#endif

	return 0;
}

/**
 * kdbus_conn_release() - release an active connection reference
 * @conn:		Connection
 *
 * This releases an active reference that has been acquired via
 * kdbus_conn_acquire(). If the connection was already disabled and this is the
 * last active-ref that is dropped, the disconnect-waiter will be woken up and
 * properly close the connection.
 */
void kdbus_conn_release(struct kdbus_conn *conn)
{
	int v;

	if (!conn)
		return;

#ifdef CONFIG_DEBUG_LOCK_ALLOC
	rwsem_release(&conn->dep_map, 1, _RET_IP_);
#endif

	v = atomic_dec_return(&conn->active);
	if (v != KDBUS_CONN_ACTIVE_BIAS)
		return;

	wake_up_all(&conn->wait);
}

static int kdbus_conn_connect(struct kdbus_conn *conn, const char *name)
{
	struct kdbus_ep *ep = conn->ep;
	struct kdbus_bus *bus = ep->bus;
	int ret;

	if (WARN_ON(atomic_read(&conn->active) != KDBUS_CONN_ACTIVE_NEW))
		return -EALREADY;

	/* make sure the ep-node is active while we add our connection */
	if (!kdbus_node_acquire(&ep->node))
		return -ESHUTDOWN;

	/* lock order: domain -> bus -> ep -> names -> conn */
	mutex_lock(&ep->lock);
	down_write(&bus->conn_rwlock);

	/* link into monitor list */
	if (kdbus_conn_is_monitor(conn))
		list_add_tail(&conn->monitor_entry, &bus->monitors_list);

	/* link into bus and endpoint */
	list_add_tail(&conn->ep_entry, &ep->conn_list);
	hash_add(bus->conn_hash, &conn->hentry, conn->id);

	/* enable lookups and acquire active ref */
	atomic_set(&conn->active, 1);
#ifdef CONFIG_DEBUG_LOCK_ALLOC
	rwsem_acquire_read(&conn->dep_map, 0, 1, _RET_IP_);
#endif

	up_write(&bus->conn_rwlock);
	mutex_unlock(&ep->lock);

	kdbus_node_release(&ep->node);

	/*
	 * Notify subscribers about the new active connection, unless it is
	 * a monitor. Monitors are invisible on the bus, can't be addressed
	 * directly, and won't cause any notifications.
	 */
	if (!kdbus_conn_is_monitor(conn)) {
		ret = kdbus_notify_id_change(bus, KDBUS_ITEM_ID_ADD,
					     conn->id, conn->flags);
		if (ret < 0)
			goto exit_disconnect;
	}

	if (kdbus_conn_is_activator(conn)) {
		u64 flags = KDBUS_NAME_ACTIVATOR;

		if (WARN_ON(!name)) {
			ret = -EINVAL;
			goto exit_disconnect;
		}

		ret = kdbus_name_acquire(bus->name_registry, conn, name,
					 flags, NULL);
		if (ret < 0)
			goto exit_disconnect;
	}

	kdbus_conn_release(conn);
	kdbus_notify_flush(bus);
	return 0;

exit_disconnect:
	kdbus_conn_release(conn);
	kdbus_conn_disconnect(conn, false);
	return ret;
}

/**
 * kdbus_conn_disconnect() - disconnect a connection
 * @conn:		The connection to disconnect
 * @ensure_queue_empty:	Flag to indicate if the call should fail in
 *			case the connection's message list is not
 *			empty
 *
 * If @ensure_msg_list_empty is true, and the connection has pending messages,
 * -EBUSY is returned.
 *
 * Return: 0 on success, negative errno on failure
 */
int kdbus_conn_disconnect(struct kdbus_conn *conn, bool ensure_queue_empty)
{
	struct kdbus_queue_entry *entry, *tmp;
	struct kdbus_bus *bus = conn->ep->bus;
	struct kdbus_reply *r, *r_tmp;
	struct kdbus_conn *c;
	int i, v;

	mutex_lock(&conn->lock);
	v = atomic_read(&conn->active);
	if (v == KDBUS_CONN_ACTIVE_NEW) {
		/* was never connected */
		mutex_unlock(&conn->lock);
		return 0;
	}
	if (v < 0) {
		/* already dead */
		mutex_unlock(&conn->lock);
		return -ECONNRESET;
	}
	if (ensure_queue_empty && !list_empty(&conn->queue.msg_list)) {
		/* still busy */
		mutex_unlock(&conn->lock);
		return -EBUSY;
	}

	atomic_add(KDBUS_CONN_ACTIVE_BIAS, &conn->active);
	mutex_unlock(&conn->lock);

	wake_up_interruptible(&conn->wait);

#ifdef CONFIG_DEBUG_LOCK_ALLOC
	rwsem_acquire(&conn->dep_map, 0, 0, _RET_IP_);
	if (atomic_read(&conn->active) != KDBUS_CONN_ACTIVE_BIAS)
		lock_contended(&conn->dep_map, _RET_IP_);
#endif

	wait_event(conn->wait,
		   atomic_read(&conn->active) == KDBUS_CONN_ACTIVE_BIAS);

#ifdef CONFIG_DEBUG_LOCK_ALLOC
	lock_acquired(&conn->dep_map, _RET_IP_);
	rwsem_release(&conn->dep_map, 1, _RET_IP_);
#endif

	cancel_delayed_work_sync(&conn->work);
	kdbus_policy_remove_owner(&conn->ep->bus->policy_db, conn);

	/* lock order: domain -> bus -> ep -> names -> conn */
	mutex_lock(&conn->ep->lock);
	down_write(&bus->conn_rwlock);

	/* remove from bus and endpoint */
	hash_del(&conn->hentry);
	list_del(&conn->monitor_entry);
	list_del(&conn->ep_entry);

	up_write(&bus->conn_rwlock);
	mutex_unlock(&conn->ep->lock);

	/*
	 * Remove all names associated with this connection; this possibly
	 * moves queued messages back to the activator connection.
	 */
	kdbus_name_release_all(bus->name_registry, conn);

	/* if we die while other connections wait for our reply, notify them */
	mutex_lock(&conn->lock);
	list_for_each_entry_safe(entry, tmp, &conn->queue.msg_list, entry) {
		if (entry->reply)
			kdbus_notify_reply_dead(bus,
						entry->reply->reply_dst->id,
						entry->reply->cookie);
		kdbus_queue_entry_free(entry);
	}

	list_for_each_entry_safe(r, r_tmp, &conn->reply_list, entry)
		kdbus_reply_unlink(r);
	mutex_unlock(&conn->lock);

	/* lock order: domain -> bus -> ep -> names -> conn */
	down_read(&bus->conn_rwlock);
	hash_for_each(bus->conn_hash, i, c, hentry) {
		mutex_lock(&c->lock);
		list_for_each_entry_safe(r, r_tmp, &c->reply_list, entry) {
			if (r->reply_src != conn)
				continue;

			if (r->sync)
				kdbus_sync_reply_wakeup(r, -EPIPE);
			else
				/* send a 'connection dead' notification */
				kdbus_notify_reply_dead(bus, c->id, r->cookie);

			kdbus_reply_unlink(r);
		}
		mutex_unlock(&c->lock);
	}
	up_read(&bus->conn_rwlock);

	if (!kdbus_conn_is_monitor(conn))
		kdbus_notify_id_change(bus, KDBUS_ITEM_ID_REMOVE,
				       conn->id, conn->flags);

	kdbus_notify_flush(bus);

	return 0;
}

/**
 * kdbus_conn_has_name() - check if a connection owns a name
 * @conn:		Connection
 * @name:		Well-know name to check for
 *
 * The caller must hold the registry lock of conn->ep->bus.
 *
 * Return: true if the name is currently owned by the connection
 */
bool kdbus_conn_has_name(struct kdbus_conn *conn, const char *name)
{
	struct kdbus_name_owner *owner;

	lockdep_assert_held(&conn->ep->bus->name_registry->rwlock);

	list_for_each_entry(owner, &conn->names_list, conn_entry)
		if (!(owner->flags & KDBUS_NAME_IN_QUEUE) &&
		    !strcmp(name, owner->name->name))
			return true;

	return false;
}

struct kdbus_quota {
	u32 memory;
	u16 msgs;
	u8 fds;
};

/**
 * kdbus_conn_quota_inc() - increase quota accounting
 * @c:		connection owning the quota tracking
 * @u:		user to account for (or NULL for kernel accounting)
 * @memory:	size of memory to account for
 * @fds:	number of FDs to account for
 *
 * This call manages the quotas on resource @c. That is, it's used if other
 * users want to use the resources of connection @c, which so far only concerns
 * the receive queue of the destination.
 *
 * This increases the quota-accounting for user @u by @memory bytes and @fds
 * file descriptors. If the user has already reached the quota limits, this call
 * will not do any accounting but return a negative error code indicating the
 * failure.
 *
 * Return: 0 on success, negative error code on failure.
 */
int kdbus_conn_quota_inc(struct kdbus_conn *c, struct kdbus_user *u,
			 size_t memory, size_t fds)
{
	struct kdbus_quota *quota;
	size_t available, accounted;
	unsigned int id;

	/*
	 * Pool Layout:
	 * 50% of a pool is always owned by the connection. It is reserved for
	 * kernel queries, handling received messages and other tasks that are
	 * under control of the pool owner. The other 50% of the pool are used
	 * as incoming queue.
	 * As we optionally support user-space based policies, we need fair
	 * allocation schemes. Furthermore, resource utilization should be
	 * maximized, so only minimal resources stay reserved. However, we need
	 * to adapt to a dynamic number of users, as we cannot know how many
	 * users will talk to a connection. Therefore, the current allocation
	 * works like this:
	 * We limit the number of bytes in a destination's pool per sending
	 * user. The space available for a user is 33% of the unused pool space
	 * (whereas the space used by the user itself is also treated as
	 * 'unused'). This way, we favor users coming first, but keep enough
	 * pool space available for any following users. Given that messages are
	 * dequeued in FIFO order, this should balance nicely if the number of
	 * users grows. At the same time, this algorithm guarantees that the
	 * space available to a connection is reduced dynamically, the more
	 * concurrent users talk to a connection.
	 */

	/* per user-accounting is expensive, so we keep state small */
	BUILD_BUG_ON(sizeof(quota->memory) != 4);
	BUILD_BUG_ON(sizeof(quota->msgs) != 2);
	BUILD_BUG_ON(sizeof(quota->fds) != 1);
	BUILD_BUG_ON(KDBUS_CONN_MAX_MSGS > U16_MAX);
	BUILD_BUG_ON(KDBUS_CONN_MAX_FDS_PER_USER > U8_MAX);

	id = u ? u->id : KDBUS_USER_KERNEL_ID;
	if (id >= c->n_quota) {
		unsigned int users;

		users = max(KDBUS_ALIGN8(id) + 8, id);
		quota = krealloc(c->quota, users * sizeof(*quota),
				 GFP_KERNEL | __GFP_ZERO);
		if (!quota)
			return -ENOMEM;

		c->n_quota = users;
		c->quota = quota;
	}

	quota = &c->quota[id];
	kdbus_pool_accounted(c->pool, &available, &accounted);

	/* half the pool is _always_ reserved for the pool owner */
	available /= 2;

	/*
	 * Pool owner slices are un-accounted slices; they can claim more
	 * than 50% of the queue. However, the slices we're dealing with here
	 * belong to the incoming queue, hence they are 'accounted' slices
	 * to which the 50%-limit applies.
	 */
	if (available < accounted)
		return -ENOBUFS;

	/* 1/3 of the remaining space (including your own memory) */
	available = (available - accounted + quota->memory) / 3;

	if (available < quota->memory ||
	    available - quota->memory < memory ||
	    quota->memory + memory > U32_MAX)
		return -ENOBUFS;
	if (quota->msgs >= KDBUS_CONN_MAX_MSGS)
		return -ENOBUFS;
	if (quota->fds + fds < quota->fds ||
	    quota->fds + fds > KDBUS_CONN_MAX_FDS_PER_USER)
		return -EMFILE;

	quota->memory += memory;
	quota->fds += fds;
	++quota->msgs;
	return 0;
}

/**
 * kdbus_conn_quota_dec() - decrease quota accounting
 * @c:		connection owning the quota tracking
 * @u:		user which was accounted for (or NULL for kernel accounting)
 * @memory:	size of memory which was accounted for
 * @fds:	number of FDs which were accounted for
 *
 * This does the reverse of kdbus_conn_quota_inc(). You have to release any
 * accounted resources that you called kdbus_conn_quota_inc() for. However, you
 * must not call kdbus_conn_quota_dec() if the accounting failed (that is,
 * kdbus_conn_quota_inc() failed).
 */
void kdbus_conn_quota_dec(struct kdbus_conn *c, struct kdbus_user *u,
			  size_t memory, size_t fds)
{
	struct kdbus_quota *quota;
	unsigned int id;

	id = u ? u->id : KDBUS_USER_KERNEL_ID;
	if (WARN_ON(id >= c->n_quota))
		return;

	quota = &c->quota[id];

	if (!WARN_ON(quota->msgs == 0))
		--quota->msgs;
	if (!WARN_ON(quota->memory < memory))
		quota->memory -= memory;
	if (!WARN_ON(quota->fds < fds))
		quota->fds -= fds;
}

/**
 * kdbus_conn_lost_message() - handle lost messages
 * @c:		connection that lost a message
 *
 * kdbus is reliable. That means, we try hard to never lose messages. However,
 * memory is limited, so we cannot rely on transmissions to never fail.
 * Therefore, we use quota-limits to let callers know if their unicast message
 * cannot be transmitted to a peer. This works fine for unicasts, but for
 * broadcasts we cannot make the caller handle the transmission failure.
 * Instead, we must let the destination know that it couldn't receive a
 * broadcast.
 * As this is an unlikely scenario, we keep it simple. A single lost-counter
 * remembers the number of lost messages since the last call to RECV. The next
 * message retrieval will notify the connection that it lost messages since the
 * last message retrieval and thus should resync its state.
 */
void kdbus_conn_lost_message(struct kdbus_conn *c)
{
	if (atomic_inc_return(&c->lost_count) == 1)
		wake_up_interruptible(&c->wait);
}

/* Callers should take the conn_dst lock */
static struct kdbus_queue_entry *
kdbus_conn_entry_make(struct kdbus_conn *conn_src,
		      struct kdbus_conn *conn_dst,
		      struct kdbus_staging *staging)
{
	/* The remote connection was disconnected */
	if (!kdbus_conn_active(conn_dst))
		return ERR_PTR(-ECONNRESET);

	/*
	 * If the connection does not accept file descriptors but the message
	 * has some attached, refuse it.
	 *
	 * If this is a monitor connection, accept the message. In that
	 * case, all file descriptors will be set to -1 at receive time.
	 */
	if (!kdbus_conn_is_monitor(conn_dst) &&
	    !(conn_dst->flags & KDBUS_HELLO_ACCEPT_FD) &&
	    staging->gaps && staging->gaps->n_fds > 0)
		return ERR_PTR(-ECOMM);

	return kdbus_queue_entry_new(conn_src, conn_dst, staging);
}

/*
 * Synchronously responding to a message, allocate a queue entry
 * and attach it to the reply tracking object.
 * The connection's queue will never get to see it.
 */
static int kdbus_conn_entry_sync_attach(struct kdbus_conn *conn_dst,
					struct kdbus_staging *staging,
					struct kdbus_reply *reply_wake)
{
	struct kdbus_queue_entry *entry;
	int remote_ret, ret = 0;

	mutex_lock(&reply_wake->reply_dst->lock);

	/*
	 * If we are still waiting then proceed, allocate a queue
	 * entry and attach it to the reply object
	 */
	if (reply_wake->waiting) {
		entry = kdbus_conn_entry_make(reply_wake->reply_src, conn_dst,
					      staging);
		if (IS_ERR(entry))
			ret = PTR_ERR(entry);
		else
			/* Attach the entry to the reply object */
			reply_wake->queue_entry = entry;
	} else {
		ret = -ECONNRESET;
	}

	/*
	 * Update the reply object and wake up remote peer only
	 * on appropriate return codes
	 *
	 * * -ECOMM: if the replying connection failed with -ECOMM
	 *           then wakeup remote peer with -EREMOTEIO
	 *
	 *           We do this to differenciate between -ECOMM errors
	 *           from the original sender perspective:
	 *           -ECOMM error during the sync send and
	 *           -ECOMM error during the sync reply, this last
	 *           one is rewritten to -EREMOTEIO
	 *
	 * * Wake up on all other return codes.
	 */
	remote_ret = ret;

	if (ret == -ECOMM)
		remote_ret = -EREMOTEIO;

	kdbus_sync_reply_wakeup(reply_wake, remote_ret);
	kdbus_reply_unlink(reply_wake);
	mutex_unlock(&reply_wake->reply_dst->lock);

	return ret;
}

/**
 * kdbus_conn_entry_insert() - enqueue a message into the receiver's pool
 * @conn_src:		The sending connection
 * @conn_dst:		The connection to queue into
 * @staging:		Message to send
 * @reply:		The reply tracker to attach to the queue entry
 * @name:		Destination name this msg is sent to, or NULL
 *
 * Return: 0 on success. negative error otherwise.
 */
int kdbus_conn_entry_insert(struct kdbus_conn *conn_src,
			    struct kdbus_conn *conn_dst,
			    struct kdbus_staging *staging,
			    struct kdbus_reply *reply,
			    const struct kdbus_name_entry *name)
{
	struct kdbus_queue_entry *entry;
	int ret;

	kdbus_conn_lock2(conn_src, conn_dst);

	entry = kdbus_conn_entry_make(conn_src, conn_dst, staging);
	if (IS_ERR(entry)) {
		ret = PTR_ERR(entry);
		goto exit_unlock;
	}

	if (reply) {
		kdbus_reply_link(reply);
		if (!reply->sync)
			schedule_delayed_work(&conn_src->work, 0);
	}

	/*
	 * Record the sequence number of the registered name; it will
	 * be remembered by the queue, in case messages addressed to a
	 * name need to be moved from or to an activator.
	 */
	if (name)
		entry->dst_name_id = name->name_id;

	kdbus_queue_entry_enqueue(entry, reply);
	wake_up_interruptible(&conn_dst->wait);

	ret = 0;

exit_unlock:
	kdbus_conn_unlock2(conn_src, conn_dst);
	return ret;
}

static int kdbus_conn_wait_reply(struct kdbus_conn *conn_src,
				 struct kdbus_cmd_send *cmd_send,
				 struct file *ioctl_file,
				 struct file *cancel_fd,
				 struct kdbus_reply *reply_wait,
				 ktime_t expire)
{
	struct kdbus_queue_entry *entry;
	struct poll_wqueues pwq = {};
	int ret;

	if (WARN_ON(!reply_wait))
		return -EIO;

	/*
	 * Block until the reply arrives. reply_wait is left untouched
	 * by the timeout scans that might be conducted for other,
	 * asynchronous replies of conn_src.
	 */

	poll_initwait(&pwq);
	poll_wait(ioctl_file, &conn_src->wait, &pwq.pt);

	for (;;) {
		/*
		 * Any of the following conditions will stop our synchronously
		 * blocking SEND command:
		 *
		 * a) The origin sender closed its connection
		 * b) The remote peer answered, setting reply_wait->waiting = 0
		 * c) The cancel FD was written to
		 * d) A signal was received
		 * e) The specified timeout was reached, and none of the above
		 *    conditions kicked in.
		 */

		/*
		 * We have already acquired an active reference when
		 * entering here, but another thread may call
		 * KDBUS_CMD_BYEBYE which does not acquire an active
		 * reference, therefore kdbus_conn_disconnect() will
		 * not wait for us.
		 */
		if (!kdbus_conn_active(conn_src)) {
			ret = -ECONNRESET;
			break;
		}

		/*
		 * After the replying peer unset the waiting variable
		 * it will wake up us.
		 */
		if (!reply_wait->waiting) {
			ret = reply_wait->err;
			break;
		}

		if (cancel_fd) {
			unsigned int r;

			r = cancel_fd->f_op->poll(cancel_fd, &pwq.pt);
			if (r & POLLIN) {
				ret = -ECANCELED;
				break;
			}
		}

		if (signal_pending(current)) {
			ret = -EINTR;
			break;
		}

		if (!poll_schedule_timeout(&pwq, TASK_INTERRUPTIBLE,
					   &expire, 0)) {
			ret = -ETIMEDOUT;
			break;
		}

		/*
		 * Reset the poll worker func, so the waitqueues are not
		 * added to the poll table again. We just reuse what we've
		 * collected earlier for further iterations.
		 */
		init_poll_funcptr(&pwq.pt, NULL);
	}

	poll_freewait(&pwq);

	if (ret == -EINTR) {
		/*
		 * Interrupted system call. Unref the reply object, and pass
		 * the return value down the chain. Mark the reply as
		 * interrupted, so the cleanup work can remove it, but do not
		 * unlink it from the list. Once the syscall restarts, we'll
		 * pick it up and wait on it again.
		 */
		mutex_lock(&conn_src->lock);
		reply_wait->interrupted = true;
		schedule_delayed_work(&conn_src->work, 0);
		mutex_unlock(&conn_src->lock);

		return -ERESTARTSYS;
	}

	mutex_lock(&conn_src->lock);
	reply_wait->waiting = false;
	entry = reply_wait->queue_entry;
	if (entry) {
		ret = kdbus_queue_entry_install(entry,
						&cmd_send->reply.return_flags,
						true);
		kdbus_pool_slice_publish(entry->slice, &cmd_send->reply.offset,
					 &cmd_send->reply.msg_size);
		kdbus_queue_entry_free(entry);
	}
	kdbus_reply_unlink(reply_wait);
	mutex_unlock(&conn_src->lock);

	return ret;
}

static int kdbus_pin_dst(struct kdbus_bus *bus,
			 struct kdbus_staging *staging,
			 struct kdbus_name_entry **out_name,
			 struct kdbus_conn **out_dst)
{
	const struct kdbus_msg *msg = staging->msg;
	struct kdbus_name_owner *owner = NULL;
	struct kdbus_name_entry *name = NULL;
	struct kdbus_conn *dst = NULL;
	int ret;

	lockdep_assert_held(&bus->name_registry->rwlock);

	if (!staging->dst_name) {
		dst = kdbus_bus_find_conn_by_id(bus, msg->dst_id);
		if (!dst)
			return -ENXIO;

		if (!kdbus_conn_is_ordinary(dst)) {
			ret = -ENXIO;
			goto error;
		}
	} else {
		name = kdbus_name_lookup_unlocked(bus->name_registry,
						  staging->dst_name);
		if (name)
			owner = kdbus_name_get_owner(name);
		if (!owner)
			return -ESRCH;

		/*
		 * If both a name and a connection ID are given as destination
		 * of a message, check that the currently owning connection of
		 * the name matches the specified ID.
		 * This way, we allow userspace to send the message to a
		 * specific connection by ID only if the connection currently
		 * owns the given name.
		 */
		if (msg->dst_id != KDBUS_DST_ID_NAME &&
		    msg->dst_id != owner->conn->id)
			return -EREMCHG;

		if ((msg->flags & KDBUS_MSG_NO_AUTO_START) &&
		    kdbus_conn_is_activator(owner->conn))
			return -EADDRNOTAVAIL;

		dst = kdbus_conn_ref(owner->conn);
	}

	*out_name = name;
	*out_dst = dst;
	return 0;

error:
	kdbus_conn_unref(dst);
	return ret;
}

static int kdbus_conn_reply(struct kdbus_conn *src,
			    struct kdbus_staging *staging)
{
	const struct kdbus_msg *msg = staging->msg;
	struct kdbus_name_entry *name = NULL;
	struct kdbus_reply *reply, *wake = NULL;
	struct kdbus_conn *dst = NULL;
	struct kdbus_bus *bus = src->ep->bus;
	int ret;

	if (WARN_ON(msg->dst_id == KDBUS_DST_ID_BROADCAST) ||
	    WARN_ON(msg->flags & KDBUS_MSG_EXPECT_REPLY) ||
	    WARN_ON(msg->flags & KDBUS_MSG_SIGNAL))
		return -EINVAL;

	/* name-registry must be locked for lookup *and* collecting data */
	down_read(&bus->name_registry->rwlock);

	/* find and pin destination */

	ret = kdbus_pin_dst(bus, staging, &name, &dst);
	if (ret < 0)
		goto exit;

	mutex_lock(&dst->lock);
	reply = kdbus_reply_find(src, dst, msg->cookie_reply);
	if (reply) {
		if (reply->sync)
			wake = kdbus_reply_ref(reply);
		kdbus_reply_unlink(reply);
	}
	mutex_unlock(&dst->lock);

	if (!reply) {
		ret = -EBADSLT;
		goto exit;
	}

	/* send message */

	kdbus_bus_eavesdrop(bus, src, staging);

	if (wake)
		ret = kdbus_conn_entry_sync_attach(dst, staging, wake);
	else
		ret = kdbus_conn_entry_insert(src, dst, staging, NULL, name);

exit:
	up_read(&bus->name_registry->rwlock);
	kdbus_reply_unref(wake);
	kdbus_conn_unref(dst);
	return ret;
}

static struct kdbus_reply *kdbus_conn_call(struct kdbus_conn *src,
					   struct kdbus_staging *staging,
					   ktime_t exp)
{
	const struct kdbus_msg *msg = staging->msg;
	struct kdbus_name_entry *name = NULL;
	struct kdbus_reply *wait = NULL;
	struct kdbus_conn *dst = NULL;
	struct kdbus_bus *bus = src->ep->bus;
	int ret;

	if (WARN_ON(msg->dst_id == KDBUS_DST_ID_BROADCAST) ||
	    WARN_ON(msg->flags & KDBUS_MSG_SIGNAL) ||
	    WARN_ON(!(msg->flags & KDBUS_MSG_EXPECT_REPLY)))
		return ERR_PTR(-EINVAL);

	/* resume previous wait-context, if available */

	mutex_lock(&src->lock);
	wait = kdbus_reply_find(NULL, src, msg->cookie);
	if (wait) {
		if (wait->interrupted) {
			kdbus_reply_ref(wait);
			wait->interrupted = false;
		} else {
			wait = NULL;
		}
	}
	mutex_unlock(&src->lock);

	if (wait)
		return wait;

	if (ktime_compare(ktime_get(), exp) >= 0)
		return ERR_PTR(-ETIMEDOUT);

	/* name-registry must be locked for lookup *and* collecting data */
	down_read(&bus->name_registry->rwlock);

	/* find and pin destination */

	ret = kdbus_pin_dst(bus, staging, &name, &dst);
	if (ret < 0)
		goto exit;

	if (!kdbus_conn_policy_talk(src, current_cred(), dst)) {
		ret = -EPERM;
		goto exit;
	}

	wait = kdbus_reply_new(dst, src, msg, name, true);
	if (IS_ERR(wait)) {
		ret = PTR_ERR(wait);
		wait = NULL;
		goto exit;
	}

	/* send message */

	kdbus_bus_eavesdrop(bus, src, staging);

	ret = kdbus_conn_entry_insert(src, dst, staging, wait, name);
	if (ret < 0)
		goto exit;

	ret = 0;

exit:
	up_read(&bus->name_registry->rwlock);
	if (ret < 0) {
		kdbus_reply_unref(wait);
		wait = ERR_PTR(ret);
	}
	kdbus_conn_unref(dst);
	return wait;
}

static int kdbus_conn_unicast(struct kdbus_conn *src,
			      struct kdbus_staging *staging)
{
	const struct kdbus_msg *msg = staging->msg;
	struct kdbus_name_entry *name = NULL;
	struct kdbus_reply *wait = NULL;
	struct kdbus_conn *dst = NULL;
	struct kdbus_bus *bus = src->ep->bus;
	bool is_signal = (msg->flags & KDBUS_MSG_SIGNAL);
	int ret = 0;

	if (WARN_ON(msg->dst_id == KDBUS_DST_ID_BROADCAST) ||
	    WARN_ON(!(msg->flags & KDBUS_MSG_EXPECT_REPLY) &&
		    msg->cookie_reply != 0))
		return -EINVAL;

	/* name-registry must be locked for lookup *and* collecting data */
	down_read(&bus->name_registry->rwlock);

	/* find and pin destination */

	ret = kdbus_pin_dst(bus, staging, &name, &dst);
	if (ret < 0)
		goto exit;

	if (is_signal) {
		/* like broadcasts we eavesdrop even if the msg is dropped */
		kdbus_bus_eavesdrop(bus, src, staging);

		/* drop silently if peer is not interested or not privileged */
		if (!kdbus_match_db_match_msg(dst->match_db, src, staging) ||
		    !kdbus_conn_policy_talk(dst, NULL, src))
			goto exit;
	} else if (!kdbus_conn_policy_talk(src, current_cred(), dst)) {
		ret = -EPERM;
		goto exit;
	} else if (msg->flags & KDBUS_MSG_EXPECT_REPLY) {
		wait = kdbus_reply_new(dst, src, msg, name, false);
		if (IS_ERR(wait)) {
			ret = PTR_ERR(wait);
			wait = NULL;
			goto exit;
		}
	}

	/* send message */

	if (!is_signal)
		kdbus_bus_eavesdrop(bus, src, staging);

	ret = kdbus_conn_entry_insert(src, dst, staging, wait, name);
	if (ret < 0 && !is_signal)
		goto exit;

	/* signals are treated like broadcasts, recv-errors are ignored */
	ret = 0;

exit:
	up_read(&bus->name_registry->rwlock);
	kdbus_reply_unref(wait);
	kdbus_conn_unref(dst);
	return ret;
}

/**
 * kdbus_conn_move_messages() - move messages from one connection to another
 * @conn_dst:		Connection to copy to
 * @conn_src:		Connection to copy from
 * @name_id:		Filter for the sequence number of the registered
 *			name, 0 means no filtering.
 *
 * Move all messages from one connection to another. This is used when
 * an implementer connection is taking over/giving back a well-known name
 * from/to an activator connection.
 */
void kdbus_conn_move_messages(struct kdbus_conn *conn_dst,
			      struct kdbus_conn *conn_src,
			      u64 name_id)
{
	struct kdbus_queue_entry *e, *e_tmp;
	struct kdbus_reply *r, *r_tmp;
	struct kdbus_bus *bus;
	struct kdbus_conn *c;
	LIST_HEAD(msg_list);
	int i, ret = 0;

	if (WARN_ON(conn_src == conn_dst))
		return;

	bus = conn_src->ep->bus;

	/* lock order: domain -> bus -> ep -> names -> conn */
	down_read(&bus->conn_rwlock);
	hash_for_each(bus->conn_hash, i, c, hentry) {
		if (c == conn_src || c == conn_dst)
			continue;

		mutex_lock(&c->lock);
		list_for_each_entry_safe(r, r_tmp, &c->reply_list, entry) {
			if (r->reply_src != conn_src)
				continue;

			/* filter messages for a specific name */
			if (name_id > 0 && r->name_id != name_id)
				continue;

			kdbus_conn_unref(r->reply_src);
			r->reply_src = kdbus_conn_ref(conn_dst);
		}
		mutex_unlock(&c->lock);
	}
	up_read(&bus->conn_rwlock);

	kdbus_conn_lock2(conn_src, conn_dst);
	list_for_each_entry_safe(e, e_tmp, &conn_src->queue.msg_list, entry) {
		/* filter messages for a specific name */
		if (name_id > 0 && e->dst_name_id != name_id)
			continue;

		if (!(conn_dst->flags & KDBUS_HELLO_ACCEPT_FD) &&
		    e->gaps && e->gaps->n_fds > 0) {
			kdbus_conn_lost_message(conn_dst);
			kdbus_queue_entry_free(e);
			continue;
		}

		ret = kdbus_queue_entry_move(e, conn_dst);
		if (ret < 0) {
			kdbus_conn_lost_message(conn_dst);
			kdbus_queue_entry_free(e);
			continue;
		}
	}
	kdbus_conn_unlock2(conn_src, conn_dst);

	/* wake up poll() */
	wake_up_interruptible(&conn_dst->wait);
}

/* query the policy-database for all names of @whom */
static bool kdbus_conn_policy_query_all(struct kdbus_conn *conn,
					const struct cred *conn_creds,
					struct kdbus_policy_db *db,
					struct kdbus_conn *whom,
					unsigned int access)
{
	struct kdbus_name_owner *owner;
	bool pass = false;
	int res;

	lockdep_assert_held(&conn->ep->bus->name_registry->rwlock);

	down_read(&db->entries_rwlock);
	mutex_lock(&whom->lock);

	list_for_each_entry(owner, &whom->names_list, conn_entry) {
		if (owner->flags & KDBUS_NAME_IN_QUEUE)
			continue;

		res = kdbus_policy_query_unlocked(db,
					conn_creds ? : conn->cred,
					owner->name->name,
					kdbus_strhash(owner->name->name));
		if (res >= (int)access) {
			pass = true;
			break;
		}
	}

	mutex_unlock(&whom->lock);
	up_read(&db->entries_rwlock);

	return pass;
}

/**
 * kdbus_conn_policy_own_name() - verify a connection can own the given name
 * @conn:		Connection
 * @conn_creds:		Credentials of @conn to use for policy check
 * @name:		Name
 *
 * This verifies that @conn is allowed to acquire the well-known name @name.
 *
 * Return: true if allowed, false if not.
 */
bool kdbus_conn_policy_own_name(struct kdbus_conn *conn,
				const struct cred *conn_creds,
				const char *name)
{
	unsigned int hash = kdbus_strhash(name);
	int res;

	if (!conn_creds)
		conn_creds = conn->cred;

	if (conn->ep->user) {
		res = kdbus_policy_query(&conn->ep->policy_db, conn_creds,
					 name, hash);
		if (res < KDBUS_POLICY_OWN)
			return false;
	}

	if (conn->owner)
		return true;

	res = kdbus_policy_query(&conn->ep->bus->policy_db, conn_creds,
				 name, hash);
	return res >= KDBUS_POLICY_OWN;
}

/**
 * kdbus_conn_policy_talk() - verify a connection can talk to a given peer
 * @conn:		Connection that tries to talk
 * @conn_creds:		Credentials of @conn to use for policy check
 * @to:			Connection that is talked to
 *
 * This verifies that @conn is allowed to talk to @to.
 *
 * Return: true if allowed, false if not.
 */
bool kdbus_conn_policy_talk(struct kdbus_conn *conn,
			    const struct cred *conn_creds,
			    struct kdbus_conn *to)
{
	if (!conn_creds)
		conn_creds = conn->cred;

	if (conn->ep->user &&
	    !kdbus_conn_policy_query_all(conn, conn_creds, &conn->ep->policy_db,
					 to, KDBUS_POLICY_TALK))
		return false;

	if (conn->owner)
		return true;
	if (uid_eq(conn_creds->euid, to->cred->uid))
		return true;

	return kdbus_conn_policy_query_all(conn, conn_creds,
					   &conn->ep->bus->policy_db, to,
					   KDBUS_POLICY_TALK);
}

/**
 * kdbus_conn_policy_see_name_unlocked() - verify a connection can see a given
 *					   name
 * @conn:		Connection
 * @conn_creds:		Credentials of @conn to use for policy check
 * @name:		Name
 *
 * This verifies that @conn is allowed to see the well-known name @name. Caller
 * must hold policy-lock.
 *
 * Return: true if allowed, false if not.
 */
bool kdbus_conn_policy_see_name_unlocked(struct kdbus_conn *conn,
					 const struct cred *conn_creds,
					 const char *name)
{
	int res;

	/*
	 * By default, all names are visible on a bus. SEE policies can only be
	 * installed on custom endpoints, where by default no name is visible.
	 */
	if (!conn->ep->user)
		return true;

	res = kdbus_policy_query_unlocked(&conn->ep->policy_db,
					  conn_creds ? : conn->cred,
					  name, kdbus_strhash(name));
	return res >= KDBUS_POLICY_SEE;
}

static bool kdbus_conn_policy_see_name(struct kdbus_conn *conn,
				       const struct cred *conn_creds,
				       const char *name)
{
	bool res;

	down_read(&conn->ep->policy_db.entries_rwlock);
	res = kdbus_conn_policy_see_name_unlocked(conn, conn_creds, name);
	up_read(&conn->ep->policy_db.entries_rwlock);

	return res;
}

static bool kdbus_conn_policy_see(struct kdbus_conn *conn,
				  const struct cred *conn_creds,
				  struct kdbus_conn *whom)
{
	/*
	 * By default, all names are visible on a bus, so a connection can
	 * always see other connections. SEE policies can only be installed on
	 * custom endpoints, where by default no name is visible and we hide
	 * peers from each other, unless you see at least _one_ name of the
	 * peer.
	 */
	return !conn->ep->user ||
	       kdbus_conn_policy_query_all(conn, conn_creds,
					   &conn->ep->policy_db, whom,
					   KDBUS_POLICY_SEE);
}

/**
 * kdbus_conn_policy_see_notification() - verify a connection is allowed to
 *					  receive a given kernel notification
 * @conn:		Connection
 * @conn_creds:		Credentials of @conn to use for policy check
 * @msg:		Notification message
 *
 * This checks whether @conn is allowed to see the kernel notification.
 *
 * Return: true if allowed, false if not.
 */
bool kdbus_conn_policy_see_notification(struct kdbus_conn *conn,
					const struct cred *conn_creds,
					const struct kdbus_msg *msg)
{
	/*
	 * Depending on the notification type, broadcasted kernel notifications
	 * have to be filtered:
	 *
	 * KDBUS_ITEM_NAME_{ADD,REMOVE,CHANGE}: This notification is forwarded
	 *     to a peer if, and only if, that peer can see the name this
	 *     notification is for.
	 *
	 * KDBUS_ITEM_ID_{ADD,REMOVE}: Notifications for ID changes are
	 *     broadcast to everyone, to allow tracking peers.
	 */

	switch (msg->items[0].type) {
	case KDBUS_ITEM_NAME_ADD:
	case KDBUS_ITEM_NAME_REMOVE:
	case KDBUS_ITEM_NAME_CHANGE:
		return kdbus_conn_policy_see_name(conn, conn_creds,
					msg->items[0].name_change.name);

	case KDBUS_ITEM_ID_ADD:
	case KDBUS_ITEM_ID_REMOVE:
		return true;

	default:
		WARN(1, "Invalid type for notification broadcast: %llu\n",
		     (unsigned long long)msg->items[0].type);
		return false;
	}
}

/**
 * kdbus_cmd_hello() - handle KDBUS_CMD_HELLO
 * @ep:			Endpoint to operate on
 * @file:		File this connection is opened on
 * @argp:		Command payload
 *
 * Return: NULL or newly created connection on success, ERR_PTR on failure.
 */
struct kdbus_conn *kdbus_cmd_hello(struct kdbus_ep *ep, struct file *file,
				   void __user *argp)
{
	struct kdbus_cmd_hello *cmd;
	struct kdbus_conn *c = NULL;
	const char *item_name;
	int ret;

	struct kdbus_arg argv[] = {
		{ .type = KDBUS_ITEM_NEGOTIATE },
		{ .type = KDBUS_ITEM_NAME },
		{ .type = KDBUS_ITEM_CREDS },
		{ .type = KDBUS_ITEM_PIDS },
		{ .type = KDBUS_ITEM_SECLABEL },
		{ .type = KDBUS_ITEM_CONN_DESCRIPTION },
		{ .type = KDBUS_ITEM_POLICY_ACCESS, .multiple = true },
	};
	struct kdbus_args args = {
		.allowed_flags = KDBUS_FLAG_NEGOTIATE |
				 KDBUS_HELLO_ACCEPT_FD |
				 KDBUS_HELLO_ACTIVATOR |
				 KDBUS_HELLO_POLICY_HOLDER |
				 KDBUS_HELLO_MONITOR,
		.argv = argv,
		.argc = ARRAY_SIZE(argv),
	};

	ret = kdbus_args_parse(&args, argp, &cmd);
	if (ret < 0)
		return ERR_PTR(ret);
	if (ret > 0)
		return NULL;

	item_name = argv[1].item ? argv[1].item->str : NULL;

	c = kdbus_conn_new(ep, file, cmd, item_name,
			   argv[2].item ? &argv[2].item->creds : NULL,
			   argv[3].item ? &argv[3].item->pids : NULL,
			   argv[4].item ? argv[4].item->str : NULL,
			   argv[5].item ? argv[5].item->str : NULL);
	if (IS_ERR(c)) {
		ret = PTR_ERR(c);
		c = NULL;
		goto exit;
	}

	ret = kdbus_conn_connect(c, item_name);
	if (ret < 0)
		goto exit;

	if (kdbus_conn_is_activator(c) || kdbus_conn_is_policy_holder(c)) {
		ret = kdbus_conn_acquire(c);
		if (ret < 0)
			goto exit;

		ret = kdbus_policy_set(&c->ep->bus->policy_db, args.items,
				       args.items_size, 1,
				       kdbus_conn_is_policy_holder(c), c);
		kdbus_conn_release(c);
		if (ret < 0)
			goto exit;
	}

	if (copy_to_user(argp, cmd, sizeof(*cmd)))
		ret = -EFAULT;

exit:
	ret = kdbus_args_clear(&args, ret);
	if (ret < 0) {
		if (c) {
			kdbus_conn_disconnect(c, false);
			kdbus_conn_unref(c);
		}
		return ERR_PTR(ret);
	}
	return c;
}

/**
 * kdbus_cmd_byebye_unlocked() - handle KDBUS_CMD_BYEBYE
 * @conn:		connection to operate on
 * @argp:		command payload
 *
 * The caller must not hold any active reference to @conn or this will deadlock.
 *
 * Return: >=0 on success, negative error code on failure.
 */
int kdbus_cmd_byebye_unlocked(struct kdbus_conn *conn, void __user *argp)
{
	struct kdbus_cmd *cmd;
	int ret;

	struct kdbus_arg argv[] = {
		{ .type = KDBUS_ITEM_NEGOTIATE },
	};
	struct kdbus_args args = {
		.allowed_flags = KDBUS_FLAG_NEGOTIATE,
		.argv = argv,
		.argc = ARRAY_SIZE(argv),
	};

	if (!kdbus_conn_is_ordinary(conn))
		return -EOPNOTSUPP;

	ret = kdbus_args_parse(&args, argp, &cmd);
	if (ret != 0)
		return ret;

	ret = kdbus_conn_disconnect(conn, true);
	return kdbus_args_clear(&args, ret);
}

/**
 * kdbus_cmd_conn_info() - handle KDBUS_CMD_CONN_INFO
 * @conn:		connection to operate on
 * @argp:		command payload
 *
 * Return: >=0 on success, negative error code on failure.
 */
int kdbus_cmd_conn_info(struct kdbus_conn *conn, void __user *argp)
{
	struct kdbus_meta_conn *conn_meta = NULL;
	struct kdbus_pool_slice *slice = NULL;
	struct kdbus_name_entry *entry = NULL;
	struct kdbus_name_owner *owner = NULL;
	struct kdbus_conn *owner_conn = NULL;
	struct kdbus_item *meta_items = NULL;
	struct kdbus_info info = {};
	struct kdbus_cmd_info *cmd;
	struct kdbus_bus *bus = conn->ep->bus;
	struct kvec kvec[3];
	size_t meta_size, cnt = 0;
	const char *name;
	u64 attach_flags, size = 0;
	int ret;

	struct kdbus_arg argv[] = {
		{ .type = KDBUS_ITEM_NEGOTIATE },
		{ .type = KDBUS_ITEM_NAME },
	};
	struct kdbus_args args = {
		.allowed_flags = KDBUS_FLAG_NEGOTIATE,
		.argv = argv,
		.argc = ARRAY_SIZE(argv),
	};

	ret = kdbus_args_parse(&args, argp, &cmd);
	if (ret != 0)
		return ret;

	/* registry must be held throughout lookup *and* collecting data */
	down_read(&bus->name_registry->rwlock);

	ret = kdbus_sanitize_attach_flags(cmd->attach_flags, &attach_flags);
	if (ret < 0)
		goto exit;

	name = argv[1].item ? argv[1].item->str : NULL;

	if (name) {
		entry = kdbus_name_lookup_unlocked(bus->name_registry, name);
		if (entry)
			owner = kdbus_name_get_owner(entry);
		if (!owner ||
		    !kdbus_conn_policy_see_name(conn, current_cred(), name) ||
		    (cmd->id != 0 && owner->conn->id != cmd->id)) {
			/* pretend a name doesn't exist if you cannot see it */
			ret = -ESRCH;
			goto exit;
		}

		owner_conn = kdbus_conn_ref(owner->conn);
	} else if (cmd->id > 0) {
		owner_conn = kdbus_bus_find_conn_by_id(bus, cmd->id);
		if (!owner_conn || !kdbus_conn_policy_see(conn, current_cred(),
							  owner_conn)) {
			/* pretend an id doesn't exist if you cannot see it */
			ret = -ENXIO;
			goto exit;
		}
	} else {
		ret = -EINVAL;
		goto exit;
	}

	attach_flags &= atomic64_read(&owner_conn->attach_flags_send);

	conn_meta = kdbus_meta_conn_new();
	if (IS_ERR(conn_meta)) {
		ret = PTR_ERR(conn_meta);
		conn_meta = NULL;
		goto exit;
	}

	ret = kdbus_meta_conn_collect(conn_meta, owner_conn, 0, attach_flags);
	if (ret < 0)
		goto exit;

	ret = kdbus_meta_emit(owner_conn->meta_proc, owner_conn->meta_fake,
			      conn_meta, conn, attach_flags,
			      &meta_items, &meta_size);
	if (ret < 0)
		goto exit;

	info.id = owner_conn->id;
	info.flags = owner_conn->flags;

	kdbus_kvec_set(&kvec[cnt++], &info, sizeof(info), &size);
	if (meta_size > 0) {
		kdbus_kvec_set(&kvec[cnt++], meta_items, meta_size, &size);
		cnt += !!kdbus_kvec_pad(&kvec[cnt], &size);
	}

	info.size = size;

	slice = kdbus_pool_slice_alloc(conn->pool, size, false);
	if (IS_ERR(slice)) {
		ret = PTR_ERR(slice);
		slice = NULL;
		goto exit;
	}

	ret = kdbus_pool_slice_copy_kvec(slice, 0, kvec, cnt, size);
	if (ret < 0)
		goto exit;

	kdbus_pool_slice_publish(slice, &cmd->offset, &cmd->info_size);

	if (kdbus_member_set_user(&cmd->offset, argp, typeof(*cmd), offset) ||
	    kdbus_member_set_user(&cmd->info_size, argp,
				  typeof(*cmd), info_size)) {
		ret = -EFAULT;
		goto exit;
	}

	ret = 0;

exit:
	up_read(&bus->name_registry->rwlock);
	kdbus_pool_slice_release(slice);
	kfree(meta_items);
	kdbus_meta_conn_unref(conn_meta);
	kdbus_conn_unref(owner_conn);
	return kdbus_args_clear(&args, ret);
}

/**
 * kdbus_cmd_update() - handle KDBUS_CMD_UPDATE
 * @conn:		connection to operate on
 * @argp:		command payload
 *
 * Return: >=0 on success, negative error code on failure.
 */
int kdbus_cmd_update(struct kdbus_conn *conn, void __user *argp)
{
	struct kdbus_item *item_policy;
	u64 *item_attach_send = NULL;
	u64 *item_attach_recv = NULL;
	struct kdbus_cmd *cmd;
	u64 attach_send;
	u64 attach_recv;
	int ret;

	struct kdbus_arg argv[] = {
		{ .type = KDBUS_ITEM_NEGOTIATE },
		{ .type = KDBUS_ITEM_ATTACH_FLAGS_SEND },
		{ .type = KDBUS_ITEM_ATTACH_FLAGS_RECV },
		{ .type = KDBUS_ITEM_NAME, .multiple = true },
		{ .type = KDBUS_ITEM_POLICY_ACCESS, .multiple = true },
	};
	struct kdbus_args args = {
		.allowed_flags = KDBUS_FLAG_NEGOTIATE,
		.argv = argv,
		.argc = ARRAY_SIZE(argv),
	};

	ret = kdbus_args_parse(&args, argp, &cmd);
	if (ret != 0)
		return ret;

	item_attach_send = argv[1].item ? &argv[1].item->data64[0] : NULL;
	item_attach_recv = argv[2].item ? &argv[2].item->data64[0] : NULL;
	item_policy = argv[3].item ? : argv[4].item;

	if (item_attach_send) {
		if (!kdbus_conn_is_ordinary(conn) &&
		    !kdbus_conn_is_monitor(conn)) {
			ret = -EOPNOTSUPP;
			goto exit;
		}

		ret = kdbus_sanitize_attach_flags(*item_attach_send,
						  &attach_send);
		if (ret < 0)
			goto exit;
	}

	if (item_attach_recv) {
		if (!kdbus_conn_is_ordinary(conn) &&
		    !kdbus_conn_is_monitor(conn) &&
		    !kdbus_conn_is_activator(conn)) {
			ret = -EOPNOTSUPP;
			goto exit;
		}

		ret = kdbus_sanitize_attach_flags(*item_attach_recv,
						  &attach_recv);
		if (ret < 0)
			goto exit;
	}

	if (item_policy && !kdbus_conn_is_policy_holder(conn)) {
		ret = -EOPNOTSUPP;
		goto exit;
	}

	/* now that we verified the input, update the connection */

	if (item_policy) {
		ret = kdbus_policy_set(&conn->ep->bus->policy_db, cmd->items,
				       KDBUS_ITEMS_SIZE(cmd, items),
				       1, true, conn);
		if (ret < 0)
			goto exit;
	}

	if (item_attach_send)
		atomic64_set(&conn->attach_flags_send, attach_send);

	if (item_attach_recv)
		atomic64_set(&conn->attach_flags_recv, attach_recv);

exit:
	return kdbus_args_clear(&args, ret);
}

/**
 * kdbus_cmd_send() - handle KDBUS_CMD_SEND
 * @conn:		connection to operate on
 * @f:			file this command was called on
 * @argp:		command payload
 *
 * Return: >=0 on success, negative error code on failure.
 */
int kdbus_cmd_send(struct kdbus_conn *conn, struct file *f, void __user *argp)
{
	struct kdbus_cmd_send *cmd;
	struct kdbus_staging *staging = NULL;
	struct kdbus_msg *msg = NULL;
	struct file *cancel_fd = NULL;
	int ret, ret2;

	/* command arguments */
	struct kdbus_arg argv[] = {
		{ .type = KDBUS_ITEM_NEGOTIATE },
		{ .type = KDBUS_ITEM_CANCEL_FD },
	};
	struct kdbus_args args = {
		.allowed_flags = KDBUS_FLAG_NEGOTIATE |
				 KDBUS_SEND_SYNC_REPLY,
		.argv = argv,
		.argc = ARRAY_SIZE(argv),
	};

	/* message arguments */
	struct kdbus_arg msg_argv[] = {
		{ .type = KDBUS_ITEM_NEGOTIATE },
		{ .type = KDBUS_ITEM_PAYLOAD_VEC, .multiple = true },
		{ .type = KDBUS_ITEM_PAYLOAD_MEMFD, .multiple = true },
		{ .type = KDBUS_ITEM_FDS },
		{ .type = KDBUS_ITEM_BLOOM_FILTER },
		{ .type = KDBUS_ITEM_DST_NAME },
	};
	struct kdbus_args msg_args = {
		.allowed_flags = KDBUS_FLAG_NEGOTIATE |
				 KDBUS_MSG_EXPECT_REPLY |
				 KDBUS_MSG_NO_AUTO_START |
				 KDBUS_MSG_SIGNAL,
		.argv = msg_argv,
		.argc = ARRAY_SIZE(msg_argv),
	};

	if (!kdbus_conn_is_ordinary(conn))
		return -EOPNOTSUPP;

	/* make sure to parse both, @cmd and @msg on negotiation */

	ret = kdbus_args_parse(&args, argp, &cmd);
	if (ret < 0)
		goto exit;
	else if (ret > 0 && !cmd->msg_address) /* negotiation without msg */
		goto exit;

	ret2 = kdbus_args_parse_msg(&msg_args, KDBUS_PTR(cmd->msg_address),
				    &msg);
	if (ret2 < 0) { /* cannot parse message */
		ret = ret2;
		goto exit;
	} else if (ret2 > 0 && !ret) { /* msg-negot implies cmd-negot */
		ret = -EINVAL;
		goto exit;
	} else if (ret > 0) { /* negotiation */
		goto exit;
	}

	/* here we parsed both, @cmd and @msg, and neither wants negotiation */

	cmd->reply.return_flags = 0;
	kdbus_pool_publish_empty(conn->pool, &cmd->reply.offset,
				 &cmd->reply.msg_size);

	if (argv[1].item) {
		cancel_fd = fget(argv[1].item->fds[0]);
		if (!cancel_fd) {
			ret = -EBADF;
			goto exit;
		}

		if (!cancel_fd->f_op->poll) {
			ret = -EINVAL;
			goto exit;
		}
	}

	/* patch-in the source of this message */
	if (msg->src_id > 0 && msg->src_id != conn->id) {
		ret = -EINVAL;
		goto exit;
	}
	msg->src_id = conn->id;

	staging = kdbus_staging_new_user(conn->ep->bus, cmd, msg);
	if (IS_ERR(staging)) {
		ret = PTR_ERR(staging);
		staging = NULL;
		goto exit;
	}

	if (msg->dst_id == KDBUS_DST_ID_BROADCAST) {
		down_read(&conn->ep->bus->name_registry->rwlock);
		kdbus_bus_broadcast(conn->ep->bus, conn, staging);
		up_read(&conn->ep->bus->name_registry->rwlock);
	} else if (cmd->flags & KDBUS_SEND_SYNC_REPLY) {
		struct kdbus_reply *r;
		ktime_t exp;

		exp = ns_to_ktime(msg->timeout_ns);
		r = kdbus_conn_call(conn, staging, exp);
		if (IS_ERR(r)) {
			ret = PTR_ERR(r);
			goto exit;
		}

		ret = kdbus_conn_wait_reply(conn, cmd, f, cancel_fd, r, exp);
		kdbus_reply_unref(r);
		if (ret < 0)
			goto exit;
	} else if ((msg->flags & KDBUS_MSG_EXPECT_REPLY) ||
		   msg->cookie_reply == 0) {
		ret = kdbus_conn_unicast(conn, staging);
		if (ret < 0)
			goto exit;
	} else {
		ret = kdbus_conn_reply(conn, staging);
		if (ret < 0)
			goto exit;
	}

	if (kdbus_member_set_user(&cmd->reply, argp, typeof(*cmd), reply))
		ret = -EFAULT;

exit:
	if (cancel_fd)
		fput(cancel_fd);
	kdbus_staging_free(staging);
	ret = kdbus_args_clear(&msg_args, ret);
	return kdbus_args_clear(&args, ret);
}

/**
 * kdbus_cmd_recv() - handle KDBUS_CMD_RECV
 * @conn:		connection to operate on
 * @argp:		command payload
 *
 * Return: >=0 on success, negative error code on failure.
 */
int kdbus_cmd_recv(struct kdbus_conn *conn, void __user *argp)
{
	struct kdbus_queue_entry *entry;
	struct kdbus_cmd_recv *cmd;
	int ret;

	struct kdbus_arg argv[] = {
		{ .type = KDBUS_ITEM_NEGOTIATE },
	};
	struct kdbus_args args = {
		.allowed_flags = KDBUS_FLAG_NEGOTIATE |
				 KDBUS_RECV_PEEK |
				 KDBUS_RECV_DROP |
				 KDBUS_RECV_USE_PRIORITY,
		.argv = argv,
		.argc = ARRAY_SIZE(argv),
	};

	if (!kdbus_conn_is_ordinary(conn) &&
	    !kdbus_conn_is_monitor(conn) &&
	    !kdbus_conn_is_activator(conn))
		return -EOPNOTSUPP;

	ret = kdbus_args_parse(&args, argp, &cmd);
	if (ret != 0)
		return ret;

	cmd->dropped_msgs = 0;
	cmd->msg.return_flags = 0;
	kdbus_pool_publish_empty(conn->pool, &cmd->msg.offset,
				 &cmd->msg.msg_size);

	/* DROP+priority is not realiably, so prevent it */
	if ((cmd->flags & KDBUS_RECV_DROP) &&
	    (cmd->flags & KDBUS_RECV_USE_PRIORITY)) {
		ret = -EINVAL;
		goto exit;
	}

	mutex_lock(&conn->lock);

	entry = kdbus_queue_peek(&conn->queue, cmd->priority,
				 cmd->flags & KDBUS_RECV_USE_PRIORITY);
	if (!entry) {
		mutex_unlock(&conn->lock);
		ret = -EAGAIN;
	} else if (cmd->flags & KDBUS_RECV_DROP) {
		struct kdbus_reply *reply = kdbus_reply_ref(entry->reply);

		kdbus_queue_entry_free(entry);

		mutex_unlock(&conn->lock);

		if (reply) {
			mutex_lock(&reply->reply_dst->lock);
			if (!list_empty(&reply->entry)) {
				kdbus_reply_unlink(reply);
				if (reply->sync)
					kdbus_sync_reply_wakeup(reply, -EPIPE);
				else
					kdbus_notify_reply_dead(conn->ep->bus,
							reply->reply_dst->id,
							reply->cookie);
			}
			mutex_unlock(&reply->reply_dst->lock);
			kdbus_notify_flush(conn->ep->bus);
		}

		kdbus_reply_unref(reply);
	} else {
		bool install_fds;

		/*
		 * PEEK just returns the location of the next message. Do not
		 * install FDs nor memfds nor anything else. The only
		 * information of interest should be the message header and
		 * metadata. Any FD numbers in the payload is undefined for
		 * PEEK'ed messages.
		 * Also make sure to never install fds into a connection that
		 * has refused to receive any. Ordinary connections will not get
		 * messages with FDs queued (the receiver will get -ECOMM), but
		 * eavesdroppers might.
		 */
		install_fds = (conn->flags & KDBUS_HELLO_ACCEPT_FD) &&
			      !(cmd->flags & KDBUS_RECV_PEEK);

		ret = kdbus_queue_entry_install(entry,
						&cmd->msg.return_flags,
						install_fds);
		if (ret < 0) {
			mutex_unlock(&conn->lock);
			goto exit;
		}

		kdbus_pool_slice_publish(entry->slice, &cmd->msg.offset,
					 &cmd->msg.msg_size);

		if (!(cmd->flags & KDBUS_RECV_PEEK))
			kdbus_queue_entry_free(entry);

		mutex_unlock(&conn->lock);
	}

	cmd->dropped_msgs = atomic_xchg(&conn->lost_count, 0);
	if (cmd->dropped_msgs > 0)
		cmd->return_flags |= KDBUS_RECV_RETURN_DROPPED_MSGS;

	if (kdbus_member_set_user(&cmd->msg, argp, typeof(*cmd), msg) ||
	    kdbus_member_set_user(&cmd->dropped_msgs, argp, typeof(*cmd),
				  dropped_msgs))
		ret = -EFAULT;

exit:
	return kdbus_args_clear(&args, ret);
}

/**
 * kdbus_cmd_free() - handle KDBUS_CMD_FREE
 * @conn:		connection to operate on
 * @argp:		command payload
 *
 * Return: >=0 on success, negative error code on failure.
 */
int kdbus_cmd_free(struct kdbus_conn *conn, void __user *argp)
{
	struct kdbus_cmd_free *cmd;
	int ret;

	struct kdbus_arg argv[] = {
		{ .type = KDBUS_ITEM_NEGOTIATE },
	};
	struct kdbus_args args = {
		.allowed_flags = KDBUS_FLAG_NEGOTIATE,
		.argv = argv,
		.argc = ARRAY_SIZE(argv),
	};

	if (!kdbus_conn_is_ordinary(conn) &&
	    !kdbus_conn_is_monitor(conn) &&
	    !kdbus_conn_is_activator(conn))
		return -EOPNOTSUPP;

	ret = kdbus_args_parse(&args, argp, &cmd);
	if (ret != 0)
		return ret;

	ret = kdbus_pool_release_offset(conn->pool, cmd->offset);

	return kdbus_args_clear(&args, ret);
}