summaryrefslogtreecommitdiff
path: root/net/ipv6/tcp_ipv6.c
blob: bb7c3caf4f8536dabdcb3dbe7c90aff9c8985c90 (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
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *	TCP over IPv6
 *	Linux INET6 implementation
 *
 *	Authors:
 *	Pedro Roque		<roque@di.fc.ul.pt>
 *
 *	Based on:
 *	linux/net/ipv4/tcp.c
 *	linux/net/ipv4/tcp_input.c
 *	linux/net/ipv4/tcp_output.c
 *
 *	Fixes:
 *	Hideaki YOSHIFUJI	:	sin6_scope_id support
 *	YOSHIFUJI Hideaki @USAGI and:	Support IPV6_V6ONLY socket option, which
 *	Alexey Kuznetsov		allow both IPv4 and IPv6 sockets to bind
 *					a single port at the same time.
 *	YOSHIFUJI Hideaki @USAGI:	convert /proc/net/tcp6 to seq_file.
 */

#include <linux/bottom_half.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/jiffies.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/netdevice.h>
#include <linux/init.h>
#include <linux/jhash.h>
#include <linux/ipsec.h>
#include <linux/times.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/ipv6.h>
#include <linux/icmpv6.h>
#include <linux/random.h>
#include <linux/indirect_call_wrapper.h>

#include <net/tcp.h>
#include <net/ndisc.h>
#include <net/inet6_hashtables.h>
#include <net/inet6_connection_sock.h>
#include <net/ipv6.h>
#include <net/transp_v6.h>
#include <net/addrconf.h>
#include <net/ip6_route.h>
#include <net/ip6_checksum.h>
#include <net/inet_ecn.h>
#include <net/protocol.h>
#include <net/xfrm.h>
#include <net/snmp.h>
#include <net/dsfield.h>
#include <net/timewait_sock.h>
#include <net/inet_common.h>
#include <net/secure_seq.h>
#include <net/hotdata.h>
#include <net/busy_poll.h>

#include <linux/proc_fs.h>
#include <linux/seq_file.h>

#include <crypto/hash.h>
#include <linux/scatterlist.h>

#include <trace/events/tcp.h>

static void	tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb);
static void	tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
				      struct request_sock *req);

INDIRECT_CALLABLE_SCOPE int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb);

static const struct inet_connection_sock_af_ops ipv6_mapped;
const struct inet_connection_sock_af_ops ipv6_specific;
#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
static const struct tcp_sock_af_ops tcp_sock_ipv6_specific;
static const struct tcp_sock_af_ops tcp_sock_ipv6_mapped_specific;
#endif

/* Helper returning the inet6 address from a given tcp socket.
 * It can be used in TCP stack instead of inet6_sk(sk).
 * This avoids a dereference and allow compiler optimizations.
 * It is a specialized version of inet6_sk_generic().
 */
#define tcp_inet6_sk(sk) (&container_of_const(tcp_sk(sk), \
					      struct tcp6_sock, tcp)->inet6)

static void inet6_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
{
	struct dst_entry *dst = skb_dst(skb);

	if (dst && dst_hold_safe(dst)) {
		const struct rt6_info *rt = (const struct rt6_info *)dst;

		rcu_assign_pointer(sk->sk_rx_dst, dst);
		sk->sk_rx_dst_ifindex = skb->skb_iif;
		sk->sk_rx_dst_cookie = rt6_get_cookie(rt);
	}
}

static u32 tcp_v6_init_seq(const struct sk_buff *skb)
{
	return secure_tcpv6_seq(ipv6_hdr(skb)->daddr.s6_addr32,
				ipv6_hdr(skb)->saddr.s6_addr32,
				tcp_hdr(skb)->dest,
				tcp_hdr(skb)->source);
}

static u32 tcp_v6_init_ts_off(const struct net *net, const struct sk_buff *skb)
{
	return secure_tcpv6_ts_off(net, ipv6_hdr(skb)->daddr.s6_addr32,
				   ipv6_hdr(skb)->saddr.s6_addr32);
}

static int tcp_v6_pre_connect(struct sock *sk, struct sockaddr *uaddr,
			      int addr_len)
{
	/* This check is replicated from tcp_v6_connect() and intended to
	 * prevent BPF program called below from accessing bytes that are out
	 * of the bound specified by user in addr_len.
	 */
	if (addr_len < SIN6_LEN_RFC2133)
		return -EINVAL;

	sock_owned_by_me(sk);

	return BPF_CGROUP_RUN_PROG_INET6_CONNECT(sk, uaddr, &addr_len);
}

static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
			  int addr_len)
{
	struct sockaddr_in6 *usin = (struct sockaddr_in6 *) uaddr;
	struct inet_connection_sock *icsk = inet_csk(sk);
	struct in6_addr *saddr = NULL, *final_p, final;
	struct inet_timewait_death_row *tcp_death_row;
	struct ipv6_pinfo *np = tcp_inet6_sk(sk);
	struct inet_sock *inet = inet_sk(sk);
	struct tcp_sock *tp = tcp_sk(sk);
	struct net *net = sock_net(sk);
	struct ipv6_txoptions *opt;
	struct dst_entry *dst;
	struct flowi6 fl6;
	int addr_type;
	int err;

	if (addr_len < SIN6_LEN_RFC2133)
		return -EINVAL;

	if (usin->sin6_family != AF_INET6)
		return -EAFNOSUPPORT;

	memset(&fl6, 0, sizeof(fl6));

	if (inet6_test_bit(SNDFLOW, sk)) {
		fl6.flowlabel = usin->sin6_flowinfo&IPV6_FLOWINFO_MASK;
		IP6_ECN_flow_init(fl6.flowlabel);
		if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
			struct ip6_flowlabel *flowlabel;
			flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
			if (IS_ERR(flowlabel))
				return -EINVAL;
			fl6_sock_release(flowlabel);
		}
	}

	/*
	 *	connect() to INADDR_ANY means loopback (BSD'ism).
	 */

	if (ipv6_addr_any(&usin->sin6_addr)) {
		if (ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr))
			ipv6_addr_set_v4mapped(htonl(INADDR_LOOPBACK),
					       &usin->sin6_addr);
		else
			usin->sin6_addr = in6addr_loopback;
	}

	addr_type = ipv6_addr_type(&usin->sin6_addr);

	if (addr_type & IPV6_ADDR_MULTICAST)
		return -ENETUNREACH;

	if (addr_type&IPV6_ADDR_LINKLOCAL) {
		if (addr_len >= sizeof(struct sockaddr_in6) &&
		    usin->sin6_scope_id) {
			/* If interface is set while binding, indices
			 * must coincide.
			 */
			if (!sk_dev_equal_l3scope(sk, usin->sin6_scope_id))
				return -EINVAL;

			sk->sk_bound_dev_if = usin->sin6_scope_id;
		}

		/* Connect to link-local address requires an interface */
		if (!sk->sk_bound_dev_if)
			return -EINVAL;
	}

	if (tp->rx_opt.ts_recent_stamp &&
	    !ipv6_addr_equal(&sk->sk_v6_daddr, &usin->sin6_addr)) {
		tp->rx_opt.ts_recent = 0;
		tp->rx_opt.ts_recent_stamp = 0;
		WRITE_ONCE(tp->write_seq, 0);
	}

	sk->sk_v6_daddr = usin->sin6_addr;
	np->flow_label = fl6.flowlabel;

	/*
	 *	TCP over IPv4
	 */

	if (addr_type & IPV6_ADDR_MAPPED) {
		u32 exthdrlen = icsk->icsk_ext_hdr_len;
		struct sockaddr_in sin;

		if (ipv6_only_sock(sk))
			return -ENETUNREACH;

		sin.sin_family = AF_INET;
		sin.sin_port = usin->sin6_port;
		sin.sin_addr.s_addr = usin->sin6_addr.s6_addr32[3];

		/* Paired with READ_ONCE() in tcp_(get|set)sockopt() */
		WRITE_ONCE(icsk->icsk_af_ops, &ipv6_mapped);
		if (sk_is_mptcp(sk))
			mptcpv6_handle_mapped(sk, true);
		sk->sk_backlog_rcv = tcp_v4_do_rcv;
#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
		tp->af_specific = &tcp_sock_ipv6_mapped_specific;
#endif

		err = tcp_v4_connect(sk, (struct sockaddr *)&sin, sizeof(sin));

		if (err) {
			icsk->icsk_ext_hdr_len = exthdrlen;
			/* Paired with READ_ONCE() in tcp_(get|set)sockopt() */
			WRITE_ONCE(icsk->icsk_af_ops, &ipv6_specific);
			if (sk_is_mptcp(sk))
				mptcpv6_handle_mapped(sk, false);
			sk->sk_backlog_rcv = tcp_v6_do_rcv;
#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
			tp->af_specific = &tcp_sock_ipv6_specific;
#endif
			goto failure;
		}
		np->saddr = sk->sk_v6_rcv_saddr;

		return err;
	}

	if (!ipv6_addr_any(&sk->sk_v6_rcv_saddr))
		saddr = &sk->sk_v6_rcv_saddr;

	fl6.flowi6_proto = IPPROTO_TCP;
	fl6.daddr = sk->sk_v6_daddr;
	fl6.saddr = saddr ? *saddr : np->saddr;
	fl6.flowlabel = ip6_make_flowinfo(np->tclass, np->flow_label);
	fl6.flowi6_oif = sk->sk_bound_dev_if;
	fl6.flowi6_mark = sk->sk_mark;
	fl6.fl6_dport = usin->sin6_port;
	fl6.fl6_sport = inet->inet_sport;
	fl6.flowi6_uid = sk->sk_uid;

	opt = rcu_dereference_protected(np->opt, lockdep_sock_is_held(sk));
	final_p = fl6_update_dst(&fl6, opt, &final);

	security_sk_classify_flow(sk, flowi6_to_flowi_common(&fl6));

	dst = ip6_dst_lookup_flow(net, sk, &fl6, final_p);
	if (IS_ERR(dst)) {
		err = PTR_ERR(dst);
		goto failure;
	}

	tp->tcp_usec_ts = dst_tcp_usec_ts(dst);
	tcp_death_row = &sock_net(sk)->ipv4.tcp_death_row;

	if (!saddr) {
		saddr = &fl6.saddr;

		err = inet_bhash2_update_saddr(sk, saddr, AF_INET6);
		if (err)
			goto failure;
	}

	/* set the source address */
	np->saddr = *saddr;
	inet->inet_rcv_saddr = LOOPBACK4_IPV6;

	sk->sk_gso_type = SKB_GSO_TCPV6;
	ip6_dst_store(sk, dst, NULL, NULL);

	icsk->icsk_ext_hdr_len = 0;
	if (opt)
		icsk->icsk_ext_hdr_len = opt->opt_flen +
					 opt->opt_nflen;

	tp->rx_opt.mss_clamp = IPV6_MIN_MTU - sizeof(struct tcphdr) - sizeof(struct ipv6hdr);

	inet->inet_dport = usin->sin6_port;

	tcp_set_state(sk, TCP_SYN_SENT);
	err = inet6_hash_connect(tcp_death_row, sk);
	if (err)
		goto late_failure;

	sk_set_txhash(sk);

	if (likely(!tp->repair)) {
		if (!tp->write_seq)
			WRITE_ONCE(tp->write_seq,
				   secure_tcpv6_seq(np->saddr.s6_addr32,
						    sk->sk_v6_daddr.s6_addr32,
						    inet->inet_sport,
						    inet->inet_dport));
		tp->tsoffset = secure_tcpv6_ts_off(net, np->saddr.s6_addr32,
						   sk->sk_v6_daddr.s6_addr32);
	}

	if (tcp_fastopen_defer_connect(sk, &err))
		return err;
	if (err)
		goto late_failure;

	err = tcp_connect(sk);
	if (err)
		goto late_failure;

	return 0;

late_failure:
	tcp_set_state(sk, TCP_CLOSE);
	inet_bhash2_reset_saddr(sk);
failure:
	inet->inet_dport = 0;
	sk->sk_route_caps = 0;
	return err;
}

static void tcp_v6_mtu_reduced(struct sock *sk)
{
	struct dst_entry *dst;
	u32 mtu;

	if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE))
		return;

	mtu = READ_ONCE(tcp_sk(sk)->mtu_info);

	/* Drop requests trying to increase our current mss.
	 * Check done in __ip6_rt_update_pmtu() is too late.
	 */
	if (tcp_mtu_to_mss(sk, mtu) >= tcp_sk(sk)->mss_cache)
		return;

	dst = inet6_csk_update_pmtu(sk, mtu);
	if (!dst)
		return;

	if (inet_csk(sk)->icsk_pmtu_cookie > dst_mtu(dst)) {
		tcp_sync_mss(sk, dst_mtu(dst));
		tcp_simple_retransmit(sk);
	}
}

static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
		u8 type, u8 code, int offset, __be32 info)
{
	const struct ipv6hdr *hdr = (const struct ipv6hdr *)skb->data;
	const struct tcphdr *th = (struct tcphdr *)(skb->data+offset);
	struct net *net = dev_net(skb->dev);
	struct request_sock *fastopen;
	struct ipv6_pinfo *np;
	struct tcp_sock *tp;
	__u32 seq, snd_una;
	struct sock *sk;
	bool fatal;
	int err;

	sk = __inet6_lookup_established(net, net->ipv4.tcp_death_row.hashinfo,
					&hdr->daddr, th->dest,
					&hdr->saddr, ntohs(th->source),
					skb->dev->ifindex, inet6_sdif(skb));

	if (!sk) {
		__ICMP6_INC_STATS(net, __in6_dev_get(skb->dev),
				  ICMP6_MIB_INERRORS);
		return -ENOENT;
	}

	if (sk->sk_state == TCP_TIME_WAIT) {
		/* To increase the counter of ignored icmps for TCP-AO */
		tcp_ao_ignore_icmp(sk, AF_INET6, type, code);
		inet_twsk_put(inet_twsk(sk));
		return 0;
	}
	seq = ntohl(th->seq);
	fatal = icmpv6_err_convert(type, code, &err);
	if (sk->sk_state == TCP_NEW_SYN_RECV) {
		tcp_req_err(sk, seq, fatal);
		return 0;
	}

	if (tcp_ao_ignore_icmp(sk, AF_INET6, type, code)) {
		sock_put(sk);
		return 0;
	}

	bh_lock_sock(sk);
	if (sock_owned_by_user(sk) && type != ICMPV6_PKT_TOOBIG)
		__NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);

	if (sk->sk_state == TCP_CLOSE)
		goto out;

	if (static_branch_unlikely(&ip6_min_hopcount)) {
		/* min_hopcount can be changed concurrently from do_ipv6_setsockopt() */
		if (ipv6_hdr(skb)->hop_limit < READ_ONCE(tcp_inet6_sk(sk)->min_hopcount)) {
			__NET_INC_STATS(net, LINUX_MIB_TCPMINTTLDROP);
			goto out;
		}
	}

	tp = tcp_sk(sk);
	/* XXX (TFO) - tp->snd_una should be ISN (tcp_create_openreq_child() */
	fastopen = rcu_dereference(tp->fastopen_rsk);
	snd_una = fastopen ? tcp_rsk(fastopen)->snt_isn : tp->snd_una;
	if (sk->sk_state != TCP_LISTEN &&
	    !between(seq, snd_una, tp->snd_nxt)) {
		__NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
		goto out;
	}

	np = tcp_inet6_sk(sk);

	if (type == NDISC_REDIRECT) {
		if (!sock_owned_by_user(sk)) {
			struct dst_entry *dst = __sk_dst_check(sk, np->dst_cookie);

			if (dst)
				dst->ops->redirect(dst, sk, skb);
		}
		goto out;
	}

	if (type == ICMPV6_PKT_TOOBIG) {
		u32 mtu = ntohl(info);

		/* We are not interested in TCP_LISTEN and open_requests
		 * (SYN-ACKs send out by Linux are always <576bytes so
		 * they should go through unfragmented).
		 */
		if (sk->sk_state == TCP_LISTEN)
			goto out;

		if (!ip6_sk_accept_pmtu(sk))
			goto out;

		if (mtu < IPV6_MIN_MTU)
			goto out;

		WRITE_ONCE(tp->mtu_info, mtu);

		if (!sock_owned_by_user(sk))
			tcp_v6_mtu_reduced(sk);
		else if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED,
					   &sk->sk_tsq_flags))
			sock_hold(sk);
		goto out;
	}


	/* Might be for an request_sock */
	switch (sk->sk_state) {
	case TCP_SYN_SENT:
	case TCP_SYN_RECV:
		/* Only in fast or simultaneous open. If a fast open socket is
		 * already accepted it is treated as a connected one below.
		 */
		if (fastopen && !fastopen->sk)
			break;

		ipv6_icmp_error(sk, skb, err, th->dest, ntohl(info), (u8 *)th);

		if (!sock_owned_by_user(sk)) {
			WRITE_ONCE(sk->sk_err, err);
			sk_error_report(sk);		/* Wake people up to see the error (see connect in sock.c) */

			tcp_done(sk);
		} else {
			WRITE_ONCE(sk->sk_err_soft, err);
		}
		goto out;
	case TCP_LISTEN:
		break;
	default:
		/* check if this ICMP message allows revert of backoff.
		 * (see RFC 6069)
		 */
		if (!fastopen && type == ICMPV6_DEST_UNREACH &&
		    code == ICMPV6_NOROUTE)
			tcp_ld_RTO_revert(sk, seq);
	}

	if (!sock_owned_by_user(sk) && inet6_test_bit(RECVERR6, sk)) {
		WRITE_ONCE(sk->sk_err, err);
		sk_error_report(sk);
	} else {
		WRITE_ONCE(sk->sk_err_soft, err);
	}
out:
	bh_unlock_sock(sk);
	sock_put(sk);
	return 0;
}


static int tcp_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
			      struct flowi *fl,
			      struct request_sock *req,
			      struct tcp_fastopen_cookie *foc,
			      enum tcp_synack_type synack_type,
			      struct sk_buff *syn_skb)
{
	struct inet_request_sock *ireq = inet_rsk(req);
	const struct ipv6_pinfo *np = tcp_inet6_sk(sk);
	struct ipv6_txoptions *opt;
	struct flowi6 *fl6 = &fl->u.ip6;
	struct sk_buff *skb;
	int err = -ENOMEM;
	u8 tclass;

	/* First, grab a route. */
	if (!dst && (dst = inet6_csk_route_req(sk, fl6, req,
					       IPPROTO_TCP)) == NULL)
		goto done;

	skb = tcp_make_synack(sk, dst, req, foc, synack_type, syn_skb);

	if (skb) {
		__tcp_v6_send_check(skb, &ireq->ir_v6_loc_addr,
				    &ireq->ir_v6_rmt_addr);

		fl6->daddr = ireq->ir_v6_rmt_addr;
		if (inet6_test_bit(REPFLOW, sk) && ireq->pktopts)
			fl6->flowlabel = ip6_flowlabel(ipv6_hdr(ireq->pktopts));

		tclass = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_reflect_tos) ?
				(tcp_rsk(req)->syn_tos & ~INET_ECN_MASK) |
				(np->tclass & INET_ECN_MASK) :
				np->tclass;

		if (!INET_ECN_is_capable(tclass) &&
		    tcp_bpf_ca_needs_ecn((struct sock *)req))
			tclass |= INET_ECN_ECT_0;

		rcu_read_lock();
		opt = ireq->ipv6_opt;
		if (!opt)
			opt = rcu_dereference(np->opt);
		err = ip6_xmit(sk, skb, fl6, skb->mark ? : READ_ONCE(sk->sk_mark),
			       opt, tclass, READ_ONCE(sk->sk_priority));
		rcu_read_unlock();
		err = net_xmit_eval(err);
	}

done:
	return err;
}


static void tcp_v6_reqsk_destructor(struct request_sock *req)
{
	kfree(inet_rsk(req)->ipv6_opt);
	consume_skb(inet_rsk(req)->pktopts);
}

#ifdef CONFIG_TCP_MD5SIG
static struct tcp_md5sig_key *tcp_v6_md5_do_lookup(const struct sock *sk,
						   const struct in6_addr *addr,
						   int l3index)
{
	return tcp_md5_do_lookup(sk, l3index,
				 (union tcp_md5_addr *)addr, AF_INET6);
}

static struct tcp_md5sig_key *tcp_v6_md5_lookup(const struct sock *sk,
						const struct sock *addr_sk)
{
	int l3index;

	l3index = l3mdev_master_ifindex_by_index(sock_net(sk),
						 addr_sk->sk_bound_dev_if);
	return tcp_v6_md5_do_lookup(sk, &addr_sk->sk_v6_daddr,
				    l3index);
}

static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
				 sockptr_t optval, int optlen)
{
	struct tcp_md5sig cmd;
	struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&cmd.tcpm_addr;
	union tcp_ao_addr *addr;
	int l3index = 0;
	u8 prefixlen;
	bool l3flag;
	u8 flags;

	if (optlen < sizeof(cmd))
		return -EINVAL;

	if (copy_from_sockptr(&cmd, optval, sizeof(cmd)))
		return -EFAULT;

	if (sin6->sin6_family != AF_INET6)
		return -EINVAL;

	flags = cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX;
	l3flag = cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX;

	if (optname == TCP_MD5SIG_EXT &&
	    cmd.tcpm_flags & TCP_MD5SIG_FLAG_PREFIX) {
		prefixlen = cmd.tcpm_prefixlen;
		if (prefixlen > 128 || (ipv6_addr_v4mapped(&sin6->sin6_addr) &&
					prefixlen > 32))
			return -EINVAL;
	} else {
		prefixlen = ipv6_addr_v4mapped(&sin6->sin6_addr) ? 32 : 128;
	}

	if (optname == TCP_MD5SIG_EXT && cmd.tcpm_ifindex &&
	    cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX) {
		struct net_device *dev;

		rcu_read_lock();
		dev = dev_get_by_index_rcu(sock_net(sk), cmd.tcpm_ifindex);
		if (dev && netif_is_l3_master(dev))
			l3index = dev->ifindex;
		rcu_read_unlock();

		/* ok to reference set/not set outside of rcu;
		 * right now device MUST be an L3 master
		 */
		if (!dev || !l3index)
			return -EINVAL;
	}

	if (!cmd.tcpm_keylen) {
		if (ipv6_addr_v4mapped(&sin6->sin6_addr))
			return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin6->sin6_addr.s6_addr32[3],
					      AF_INET, prefixlen,
					      l3index, flags);
		return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin6->sin6_addr,
				      AF_INET6, prefixlen, l3index, flags);
	}

	if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
		return -EINVAL;

	if (ipv6_addr_v4mapped(&sin6->sin6_addr)) {
		addr = (union tcp_md5_addr *)&sin6->sin6_addr.s6_addr32[3];

		/* Don't allow keys for peers that have a matching TCP-AO key.
		 * See the comment in tcp_ao_add_cmd()
		 */
		if (tcp_ao_required(sk, addr, AF_INET,
				    l3flag ? l3index : -1, false))
			return -EKEYREJECTED;
		return tcp_md5_do_add(sk, addr,
				      AF_INET, prefixlen, l3index, flags,
				      cmd.tcpm_key, cmd.tcpm_keylen);
	}

	addr = (union tcp_md5_addr *)&sin6->sin6_addr;

	/* Don't allow keys for peers that have a matching TCP-AO key.
	 * See the comment in tcp_ao_add_cmd()
	 */
	if (tcp_ao_required(sk, addr, AF_INET6, l3flag ? l3index : -1, false))
		return -EKEYREJECTED;

	return tcp_md5_do_add(sk, addr, AF_INET6, prefixlen, l3index, flags,
			      cmd.tcpm_key, cmd.tcpm_keylen);
}

static int tcp_v6_md5_hash_headers(struct tcp_sigpool *hp,
				   const struct in6_addr *daddr,
				   const struct in6_addr *saddr,
				   const struct tcphdr *th, int nbytes)
{
	struct tcp6_pseudohdr *bp;
	struct scatterlist sg;
	struct tcphdr *_th;

	bp = hp->scratch;
	/* 1. TCP pseudo-header (RFC2460) */
	bp->saddr = *saddr;
	bp->daddr = *daddr;
	bp->protocol = cpu_to_be32(IPPROTO_TCP);
	bp->len = cpu_to_be32(nbytes);

	_th = (struct tcphdr *)(bp + 1);
	memcpy(_th, th, sizeof(*th));
	_th->check = 0;

	sg_init_one(&sg, bp, sizeof(*bp) + sizeof(*th));
	ahash_request_set_crypt(hp->req, &sg, NULL,
				sizeof(*bp) + sizeof(*th));
	return crypto_ahash_update(hp->req);
}

static int tcp_v6_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key,
			       const struct in6_addr *daddr, struct in6_addr *saddr,
			       const struct tcphdr *th)
{
	struct tcp_sigpool hp;

	if (tcp_sigpool_start(tcp_md5_sigpool_id, &hp))
		goto clear_hash_nostart;

	if (crypto_ahash_init(hp.req))
		goto clear_hash;
	if (tcp_v6_md5_hash_headers(&hp, daddr, saddr, th, th->doff << 2))
		goto clear_hash;
	if (tcp_md5_hash_key(&hp, key))
		goto clear_hash;
	ahash_request_set_crypt(hp.req, NULL, md5_hash, 0);
	if (crypto_ahash_final(hp.req))
		goto clear_hash;

	tcp_sigpool_end(&hp);
	return 0;

clear_hash:
	tcp_sigpool_end(&hp);
clear_hash_nostart:
	memset(md5_hash, 0, 16);
	return 1;
}

static int tcp_v6_md5_hash_skb(char *md5_hash,
			       const struct tcp_md5sig_key *key,
			       const struct sock *sk,
			       const struct sk_buff *skb)
{
	const struct tcphdr *th = tcp_hdr(skb);
	const struct in6_addr *saddr, *daddr;
	struct tcp_sigpool hp;

	if (sk) { /* valid for establish/request sockets */
		saddr = &sk->sk_v6_rcv_saddr;
		daddr = &sk->sk_v6_daddr;
	} else {
		const struct ipv6hdr *ip6h = ipv6_hdr(skb);
		saddr = &ip6h->saddr;
		daddr = &ip6h->daddr;
	}

	if (tcp_sigpool_start(tcp_md5_sigpool_id, &hp))
		goto clear_hash_nostart;

	if (crypto_ahash_init(hp.req))
		goto clear_hash;

	if (tcp_v6_md5_hash_headers(&hp, daddr, saddr, th, skb->len))
		goto clear_hash;
	if (tcp_sigpool_hash_skb_data(&hp, skb, th->doff << 2))
		goto clear_hash;
	if (tcp_md5_hash_key(&hp, key))
		goto clear_hash;
	ahash_request_set_crypt(hp.req, NULL, md5_hash, 0);
	if (crypto_ahash_final(hp.req))
		goto clear_hash;

	tcp_sigpool_end(&hp);
	return 0;

clear_hash:
	tcp_sigpool_end(&hp);
clear_hash_nostart:
	memset(md5_hash, 0, 16);
	return 1;
}
#endif

static void tcp_v6_init_req(struct request_sock *req,
			    const struct sock *sk_listener,
			    struct sk_buff *skb,
			    u32 tw_isn)
{
	bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
	struct inet_request_sock *ireq = inet_rsk(req);
	const struct ipv6_pinfo *np = tcp_inet6_sk(sk_listener);

	ireq->ir_v6_rmt_addr = ipv6_hdr(skb)->saddr;
	ireq->ir_v6_loc_addr = ipv6_hdr(skb)->daddr;

	/* So that link locals have meaning */
	if ((!sk_listener->sk_bound_dev_if || l3_slave) &&
	    ipv6_addr_type(&ireq->ir_v6_rmt_addr) & IPV6_ADDR_LINKLOCAL)
		ireq->ir_iif = tcp_v6_iif(skb);

	if (!tw_isn &&
	    (ipv6_opt_accepted(sk_listener, skb, &TCP_SKB_CB(skb)->header.h6) ||
	     np->rxopt.bits.rxinfo ||
	     np->rxopt.bits.rxoinfo || np->rxopt.bits.rxhlim ||
	     np->rxopt.bits.rxohlim || inet6_test_bit(REPFLOW, sk_listener))) {
		refcount_inc(&skb->users);
		ireq->pktopts = skb;
	}
}

static struct dst_entry *tcp_v6_route_req(const struct sock *sk,
					  struct sk_buff *skb,
					  struct flowi *fl,
					  struct request_sock *req,
					  u32 tw_isn)
{
	tcp_v6_init_req(req, sk, skb, tw_isn);

	if (security_inet_conn_request(sk, skb, req))
		return NULL;

	return inet6_csk_route_req(sk, &fl->u.ip6, req, IPPROTO_TCP);
}

struct request_sock_ops tcp6_request_sock_ops __read_mostly = {
	.family		=	AF_INET6,
	.obj_size	=	sizeof(struct tcp6_request_sock),
	.rtx_syn_ack	=	tcp_rtx_synack,
	.send_ack	=	tcp_v6_reqsk_send_ack,
	.destructor	=	tcp_v6_reqsk_destructor,
	.send_reset	=	tcp_v6_send_reset,
	.syn_ack_timeout =	tcp_syn_ack_timeout,
};

const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {
	.mss_clamp	=	IPV6_MIN_MTU - sizeof(struct tcphdr) -
				sizeof(struct ipv6hdr),
#ifdef CONFIG_TCP_MD5SIG
	.req_md5_lookup	=	tcp_v6_md5_lookup,
	.calc_md5_hash	=	tcp_v6_md5_hash_skb,
#endif
#ifdef CONFIG_TCP_AO
	.ao_lookup	=	tcp_v6_ao_lookup_rsk,
	.ao_calc_key	=	tcp_v6_ao_calc_key_rsk,
	.ao_synack_hash =	tcp_v6_ao_synack_hash,
#endif
#ifdef CONFIG_SYN_COOKIES
	.cookie_init_seq =	cookie_v6_init_sequence,
#endif
	.route_req	=	tcp_v6_route_req,
	.init_seq	=	tcp_v6_init_seq,
	.init_ts_off	=	tcp_v6_init_ts_off,
	.send_synack	=	tcp_v6_send_synack,
};

static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32 seq,
				 u32 ack, u32 win, u32 tsval, u32 tsecr,
				 int oif, int rst, u8 tclass, __be32 label,
				 u32 priority, u32 txhash, struct tcp_key *key)
{
	const struct tcphdr *th = tcp_hdr(skb);
	struct tcphdr *t1;
	struct sk_buff *buff;
	struct flowi6 fl6;
	struct net *net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
	struct sock *ctl_sk = net->ipv6.tcp_sk;
	unsigned int tot_len = sizeof(struct tcphdr);
	__be32 mrst = 0, *topt;
	struct dst_entry *dst;
	__u32 mark = 0;

	if (tsecr)
		tot_len += TCPOLEN_TSTAMP_ALIGNED;
	if (tcp_key_is_md5(key))
		tot_len += TCPOLEN_MD5SIG_ALIGNED;
	if (tcp_key_is_ao(key))
		tot_len += tcp_ao_len_aligned(key->ao_key);

#ifdef CONFIG_MPTCP
	if (rst && !tcp_key_is_md5(key)) {
		mrst = mptcp_reset_option(skb);

		if (mrst)
			tot_len += sizeof(__be32);
	}
#endif

	buff = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC);
	if (!buff)
		return;

	skb_reserve(buff, MAX_TCP_HEADER);

	t1 = skb_push(buff, tot_len);
	skb_reset_transport_header(buff);

	/* Swap the send and the receive. */
	memset(t1, 0, sizeof(*t1));
	t1->dest = th->source;
	t1->source = th->dest;
	t1->doff = tot_len / 4;
	t1->seq = htonl(seq);
	t1->ack_seq = htonl(ack);
	t1->ack = !rst || !th->ack;
	t1->rst = rst;
	t1->window = htons(win);

	topt = (__be32 *)(t1 + 1);

	if (tsecr) {
		*topt++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
				(TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP);
		*topt++ = htonl(tsval);
		*topt++ = htonl(tsecr);
	}

	if (mrst)
		*topt++ = mrst;

#ifdef CONFIG_TCP_MD5SIG
	if (tcp_key_is_md5(key)) {
		*topt++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
				(TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG);
		tcp_v6_md5_hash_hdr((__u8 *)topt, key->md5_key,
				    &ipv6_hdr(skb)->saddr,
				    &ipv6_hdr(skb)->daddr, t1);
	}
#endif
#ifdef CONFIG_TCP_AO
	if (tcp_key_is_ao(key)) {
		*topt++ = htonl((TCPOPT_AO << 24) |
				(tcp_ao_len(key->ao_key) << 16) |
				(key->ao_key->sndid << 8) |
				(key->rcv_next));

		tcp_ao_hash_hdr(AF_INET6, (char *)topt, key->ao_key,
				key->traffic_key,
				(union tcp_ao_addr *)&ipv6_hdr(skb)->saddr,
				(union tcp_ao_addr *)&ipv6_hdr(skb)->daddr,
				t1, key->sne);
	}
#endif

	memset(&fl6, 0, sizeof(fl6));
	fl6.daddr = ipv6_hdr(skb)->saddr;
	fl6.saddr = ipv6_hdr(skb)->daddr;
	fl6.flowlabel = label;

	buff->ip_summed = CHECKSUM_PARTIAL;

	__tcp_v6_send_check(buff, &fl6.saddr, &fl6.daddr);

	fl6.flowi6_proto = IPPROTO_TCP;
	if (rt6_need_strict(&fl6.daddr) && !oif)
		fl6.flowi6_oif = tcp_v6_iif(skb);
	else {
		if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
			oif = skb->skb_iif;

		fl6.flowi6_oif = oif;
	}

	if (sk) {
		if (sk->sk_state == TCP_TIME_WAIT)
			mark = inet_twsk(sk)->tw_mark;
		else
			mark = READ_ONCE(sk->sk_mark);
		skb_set_delivery_time(buff, tcp_transmit_time(sk), true);
	}
	if (txhash) {
		/* autoflowlabel/skb_get_hash_flowi6 rely on buff->hash */
		skb_set_hash(buff, txhash, PKT_HASH_TYPE_L4);
	}
	fl6.flowi6_mark = IP6_REPLY_MARK(net, skb->mark) ?: mark;
	fl6.fl6_dport = t1->dest;
	fl6.fl6_sport = t1->source;
	fl6.flowi6_uid = sock_net_uid(net, sk && sk_fullsock(sk) ? sk : NULL);
	security_skb_classify_flow(skb, flowi6_to_flowi_common(&fl6));

	/* Pass a socket to ip6_dst_lookup either it is for RST
	 * Underlying function will use this to retrieve the network
	 * namespace
	 */
	if (sk && sk->sk_state != TCP_TIME_WAIT)
		dst = ip6_dst_lookup_flow(net, sk, &fl6, NULL); /*sk's xfrm_policy can be referred*/
	else
		dst = ip6_dst_lookup_flow(net, ctl_sk, &fl6, NULL);
	if (!IS_ERR(dst)) {
		skb_dst_set(buff, dst);
		ip6_xmit(ctl_sk, buff, &fl6, fl6.flowi6_mark, NULL,
			 tclass & ~INET_ECN_MASK, priority);
		TCP_INC_STATS(net, TCP_MIB_OUTSEGS);
		if (rst)
			TCP_INC_STATS(net, TCP_MIB_OUTRSTS);
		return;
	}

	kfree_skb(buff);
}

static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
{
	const struct tcphdr *th = tcp_hdr(skb);
	struct ipv6hdr *ipv6h = ipv6_hdr(skb);
	const __u8 *md5_hash_location = NULL;
#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
	bool allocated_traffic_key = false;
#endif
	const struct tcp_ao_hdr *aoh;
	struct tcp_key key = {};
	u32 seq = 0, ack_seq = 0;
	__be32 label = 0;
	u32 priority = 0;
	struct net *net;
	u32 txhash = 0;
	int oif = 0;
#ifdef CONFIG_TCP_MD5SIG
	unsigned char newhash[16];
	int genhash;
	struct sock *sk1 = NULL;
#endif

	if (th->rst)
		return;

	/* If sk not NULL, it means we did a successful lookup and incoming
	 * route had to be correct. prequeue might have dropped our dst.
	 */
	if (!sk && !ipv6_unicast_destination(skb))
		return;

	net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
	/* Invalid TCP option size or twice included auth */
	if (tcp_parse_auth_options(th, &md5_hash_location, &aoh))
		return;
#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
	rcu_read_lock();
#endif
#ifdef CONFIG_TCP_MD5SIG
	if (sk && sk_fullsock(sk)) {
		int l3index;

		/* sdif set, means packet ingressed via a device
		 * in an L3 domain and inet_iif is set to it.
		 */
		l3index = tcp_v6_sdif(skb) ? tcp_v6_iif_l3_slave(skb) : 0;
		key.md5_key = tcp_v6_md5_do_lookup(sk, &ipv6h->saddr, l3index);
		if (key.md5_key)
			key.type = TCP_KEY_MD5;
	} else if (md5_hash_location) {
		int dif = tcp_v6_iif_l3_slave(skb);
		int sdif = tcp_v6_sdif(skb);
		int l3index;

		/*
		 * active side is lost. Try to find listening socket through
		 * source port, and then find md5 key through listening socket.
		 * we are not loose security here:
		 * Incoming packet is checked with md5 hash with finding key,
		 * no RST generated if md5 hash doesn't match.
		 */
		sk1 = inet6_lookup_listener(net, net->ipv4.tcp_death_row.hashinfo,
					    NULL, 0, &ipv6h->saddr, th->source,
					    &ipv6h->daddr, ntohs(th->source),
					    dif, sdif);
		if (!sk1)
			goto out;

		/* sdif set, means packet ingressed via a device
		 * in an L3 domain and dif is set to it.
		 */
		l3index = tcp_v6_sdif(skb) ? dif : 0;

		key.md5_key = tcp_v6_md5_do_lookup(sk1, &ipv6h->saddr, l3index);
		if (!key.md5_key)
			goto out;
		key.type = TCP_KEY_MD5;

		genhash = tcp_v6_md5_hash_skb(newhash, key.md5_key, NULL, skb);
		if (genhash || memcmp(md5_hash_location, newhash, 16) != 0)
			goto out;
	}
#endif

	if (th->ack)
		seq = ntohl(th->ack_seq);
	else
		ack_seq = ntohl(th->seq) + th->syn + th->fin + skb->len -
			  (th->doff << 2);

#ifdef CONFIG_TCP_AO
	if (aoh) {
		int l3index;

		l3index = tcp_v6_sdif(skb) ? tcp_v6_iif_l3_slave(skb) : 0;
		if (tcp_ao_prepare_reset(sk, skb, aoh, l3index, seq,
					 &key.ao_key, &key.traffic_key,
					 &allocated_traffic_key,
					 &key.rcv_next, &key.sne))
			goto out;
		key.type = TCP_KEY_AO;
	}
#endif

	if (sk) {
		oif = sk->sk_bound_dev_if;
		if (sk_fullsock(sk)) {
			if (inet6_test_bit(REPFLOW, sk))
				label = ip6_flowlabel(ipv6h);
			priority = READ_ONCE(sk->sk_priority);
			txhash = sk->sk_txhash;
		}
		if (sk->sk_state == TCP_TIME_WAIT) {
			label = cpu_to_be32(inet_twsk(sk)->tw_flowlabel);
			priority = inet_twsk(sk)->tw_priority;
			txhash = inet_twsk(sk)->tw_txhash;
		}
	} else {
		if (net->ipv6.sysctl.flowlabel_reflect & FLOWLABEL_REFLECT_TCP_RESET)
			label = ip6_flowlabel(ipv6h);
	}

	trace_tcp_send_reset(sk, skb);

	tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, 1,
			     ipv6_get_dsfield(ipv6h), label, priority, txhash,
			     &key);

#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
out:
	if (allocated_traffic_key)
		kfree(key.traffic_key);
	rcu_read_unlock();
#endif
}

static void tcp_v6_send_ack(const struct sock *sk, struct sk_buff *skb, u32 seq,
			    u32 ack, u32 win, u32 tsval, u32 tsecr, int oif,
			    struct tcp_key *key, u8 tclass,
			    __be32 label, u32 priority, u32 txhash)
{
	tcp_v6_send_response(sk, skb, seq, ack, win, tsval, tsecr, oif, 0,
			     tclass, label, priority, txhash, key);
}

static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
{
	struct inet_timewait_sock *tw = inet_twsk(sk);
	struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
	struct tcp_key key = {};
#ifdef CONFIG_TCP_AO
	struct tcp_ao_info *ao_info;

	if (static_branch_unlikely(&tcp_ao_needed.key)) {

		/* FIXME: the segment to-be-acked is not verified yet */
		ao_info = rcu_dereference(tcptw->ao_info);
		if (ao_info) {
			const struct tcp_ao_hdr *aoh;

			/* Invalid TCP option size or twice included auth */
			if (tcp_parse_auth_options(tcp_hdr(skb), NULL, &aoh))
				goto out;
			if (aoh)
				key.ao_key = tcp_ao_established_key(ao_info,
						aoh->rnext_keyid, -1);
		}
	}
	if (key.ao_key) {
		struct tcp_ao_key *rnext_key;

		key.traffic_key = snd_other_key(key.ao_key);
		/* rcv_next switches to our rcv_next */
		rnext_key = READ_ONCE(ao_info->rnext_key);
		key.rcv_next = rnext_key->rcvid;
		key.sne = READ_ONCE(ao_info->snd_sne);
		key.type = TCP_KEY_AO;
#else
	if (0) {
#endif
#ifdef CONFIG_TCP_MD5SIG
	} else if (static_branch_unlikely(&tcp_md5_needed.key)) {
		key.md5_key = tcp_twsk_md5_key(tcptw);
		if (key.md5_key)
			key.type = TCP_KEY_MD5;
#endif
	}

	tcp_v6_send_ack(sk, skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
			tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
			tcp_tw_tsval(tcptw),
			tcptw->tw_ts_recent, tw->tw_bound_dev_if, &key,
			tw->tw_tclass, cpu_to_be32(tw->tw_flowlabel), tw->tw_priority,
			tw->tw_txhash);

#ifdef CONFIG_TCP_AO
out:
#endif
	inet_twsk_put(tw);
}

static void tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
				  struct request_sock *req)
{
	struct tcp_key key = {};

#ifdef CONFIG_TCP_AO
	if (static_branch_unlikely(&tcp_ao_needed.key) &&
	    tcp_rsk_used_ao(req)) {
		const struct in6_addr *addr = &ipv6_hdr(skb)->saddr;
		const struct tcp_ao_hdr *aoh;
		int l3index;

		l3index = tcp_v6_sdif(skb) ? tcp_v6_iif_l3_slave(skb) : 0;
		/* Invalid TCP option size or twice included auth */
		if (tcp_parse_auth_options(tcp_hdr(skb), NULL, &aoh))
			return;
		if (!aoh)
			return;
		key.ao_key = tcp_ao_do_lookup(sk, l3index,
					      (union tcp_ao_addr *)addr,
					      AF_INET6, aoh->rnext_keyid, -1);
		if (unlikely(!key.ao_key)) {
			/* Send ACK with any matching MKT for the peer */
			key.ao_key = tcp_ao_do_lookup(sk, l3index,
						      (union tcp_ao_addr *)addr,
						      AF_INET6, -1, -1);
			/* Matching key disappeared (user removed the key?)
			 * let the handshake timeout.
			 */
			if (!key.ao_key) {
				net_info_ratelimited("TCP-AO key for (%pI6, %d)->(%pI6, %d) suddenly disappeared, won't ACK new connection\n",
						     addr,
						     ntohs(tcp_hdr(skb)->source),
						     &ipv6_hdr(skb)->daddr,
						     ntohs(tcp_hdr(skb)->dest));
				return;
			}
		}
		key.traffic_key = kmalloc(tcp_ao_digest_size(key.ao_key), GFP_ATOMIC);
		if (!key.traffic_key)
			return;

		key.type = TCP_KEY_AO;
		key.rcv_next = aoh->keyid;
		tcp_v6_ao_calc_key_rsk(key.ao_key, key.traffic_key, req);
#else
	if (0) {
#endif
#ifdef CONFIG_TCP_MD5SIG
	} else if (static_branch_unlikely(&tcp_md5_needed.key)) {
		int l3index = tcp_v6_sdif(skb) ? tcp_v6_iif_l3_slave(skb) : 0;

		key.md5_key = tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->saddr,
						   l3index);
		if (key.md5_key)
			key.type = TCP_KEY_MD5;
#endif
	}

	/* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV
	 * sk->sk_state == TCP_SYN_RECV -> for Fast Open.
	 */
	/* RFC 7323 2.3
	 * The window field (SEG.WND) of every outgoing segment, with the
	 * exception of <SYN> segments, MUST be right-shifted by
	 * Rcv.Wind.Shift bits:
	 */
	tcp_v6_send_ack(sk, skb, (sk->sk_state == TCP_LISTEN) ?
			tcp_rsk(req)->snt_isn + 1 : tcp_sk(sk)->snd_nxt,
			tcp_rsk(req)->rcv_nxt,
			req->rsk_rcv_wnd >> inet_rsk(req)->rcv_wscale,
			tcp_rsk_tsval(tcp_rsk(req)),
			READ_ONCE(req->ts_recent), sk->sk_bound_dev_if,
			&key, ipv6_get_dsfield(ipv6_hdr(skb)), 0,
			READ_ONCE(sk->sk_priority),
			READ_ONCE(tcp_rsk(req)->txhash));
	if (tcp_key_is_ao(&key))
		kfree(key.traffic_key);
}


static struct sock *tcp_v6_cookie_check(struct sock *sk, struct sk_buff *skb)
{
#ifdef CONFIG_SYN_COOKIES
	const struct tcphdr *th = tcp_hdr(skb);

	if (!th->syn)
		sk = cookie_v6_check(sk, skb);
#endif
	return sk;
}

u16 tcp_v6_get_syncookie(struct sock *sk, struct ipv6hdr *iph,
			 struct tcphdr *th, u32 *cookie)
{
	u16 mss = 0;
#ifdef CONFIG_SYN_COOKIES
	mss = tcp_get_syncookie_mss(&tcp6_request_sock_ops,
				    &tcp_request_sock_ipv6_ops, sk, th);
	if (mss) {
		*cookie = __cookie_v6_init_sequence(iph, th, &mss);
		tcp_synq_overflow(sk);
	}
#endif
	return mss;
}

static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
{
	if (skb->protocol == htons(ETH_P_IP))
		return tcp_v4_conn_request(sk, skb);

	if (!ipv6_unicast_destination(skb))
		goto drop;

	if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) {
		__IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
		return 0;
	}

	return tcp_conn_request(&tcp6_request_sock_ops,
				&tcp_request_sock_ipv6_ops, sk, skb);

drop:
	tcp_listendrop(sk);
	return 0; /* don't send reset */
}

static void tcp_v6_restore_cb(struct sk_buff *skb)
{
	/* We need to move header back to the beginning if xfrm6_policy_check()
	 * and tcp_v6_fill_cb() are going to be called again.
	 * ip6_datagram_recv_specific_ctl() also expects IP6CB to be there.
	 */
	memmove(IP6CB(skb), &TCP_SKB_CB(skb)->header.h6,
		sizeof(struct inet6_skb_parm));
}

static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
					 struct request_sock *req,
					 struct dst_entry *dst,
					 struct request_sock *req_unhash,
					 bool *own_req)
{
	struct inet_request_sock *ireq;
	struct ipv6_pinfo *newnp;
	const struct ipv6_pinfo *np = tcp_inet6_sk(sk);
	struct ipv6_txoptions *opt;
	struct inet_sock *newinet;
	bool found_dup_sk = false;
	struct tcp_sock *newtp;
	struct sock *newsk;
#ifdef CONFIG_TCP_MD5SIG
	struct tcp_md5sig_key *key;
	int l3index;
#endif
	struct flowi6 fl6;

	if (skb->protocol == htons(ETH_P_IP)) {
		/*
		 *	v6 mapped
		 */

		newsk = tcp_v4_syn_recv_sock(sk, skb, req, dst,
					     req_unhash, own_req);

		if (!newsk)
			return NULL;

		inet_sk(newsk)->pinet6 = tcp_inet6_sk(newsk);

		newnp = tcp_inet6_sk(newsk);
		newtp = tcp_sk(newsk);

		memcpy(newnp, np, sizeof(struct ipv6_pinfo));

		newnp->saddr = newsk->sk_v6_rcv_saddr;

		inet_csk(newsk)->icsk_af_ops = &ipv6_mapped;
		if (sk_is_mptcp(newsk))
			mptcpv6_handle_mapped(newsk, true);
		newsk->sk_backlog_rcv = tcp_v4_do_rcv;
#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
		newtp->af_specific = &tcp_sock_ipv6_mapped_specific;
#endif

		newnp->ipv6_mc_list = NULL;
		newnp->ipv6_ac_list = NULL;
		newnp->ipv6_fl_list = NULL;
		newnp->pktoptions  = NULL;
		newnp->opt	   = NULL;
		newnp->mcast_oif   = inet_iif(skb);
		newnp->mcast_hops  = ip_hdr(skb)->ttl;
		newnp->rcv_flowinfo = 0;
		if (inet6_test_bit(REPFLOW, sk))
			newnp->flow_label = 0;

		/*
		 * No need to charge this sock to the relevant IPv6 refcnt debug socks count
		 * here, tcp_create_openreq_child now does this for us, see the comment in
		 * that function for the gory details. -acme
		 */

		/* It is tricky place. Until this moment IPv4 tcp
		   worked with IPv6 icsk.icsk_af_ops.
		   Sync it now.
		 */
		tcp_sync_mss(newsk, inet_csk(newsk)->icsk_pmtu_cookie);

		return newsk;
	}

	ireq = inet_rsk(req);

	if (sk_acceptq_is_full(sk))
		goto out_overflow;

	if (!dst) {
		dst = inet6_csk_route_req(sk, &fl6, req, IPPROTO_TCP);
		if (!dst)
			goto out;
	}

	newsk = tcp_create_openreq_child(sk, req, skb);
	if (!newsk)
		goto out_nonewsk;

	/*
	 * No need to charge this sock to the relevant IPv6 refcnt debug socks
	 * count here, tcp_create_openreq_child now does this for us, see the
	 * comment in that function for the gory details. -acme
	 */

	newsk->sk_gso_type = SKB_GSO_TCPV6;
	ip6_dst_store(newsk, dst, NULL, NULL);
	inet6_sk_rx_dst_set(newsk, skb);

	inet_sk(newsk)->pinet6 = tcp_inet6_sk(newsk);

	newtp = tcp_sk(newsk);
	newinet = inet_sk(newsk);
	newnp = tcp_inet6_sk(newsk);

	memcpy(newnp, np, sizeof(struct ipv6_pinfo));

	newsk->sk_v6_daddr = ireq->ir_v6_rmt_addr;
	newnp->saddr = ireq->ir_v6_loc_addr;
	newsk->sk_v6_rcv_saddr = ireq->ir_v6_loc_addr;
	newsk->sk_bound_dev_if = ireq->ir_iif;

	/* Now IPv6 options...

	   First: no IPv4 options.
	 */
	newinet->inet_opt = NULL;
	newnp->ipv6_mc_list = NULL;
	newnp->ipv6_ac_list = NULL;
	newnp->ipv6_fl_list = NULL;

	/* Clone RX bits */
	newnp->rxopt.all = np->rxopt.all;

	newnp->pktoptions = NULL;
	newnp->opt	  = NULL;
	newnp->mcast_oif  = tcp_v6_iif(skb);
	newnp->mcast_hops = ipv6_hdr(skb)->hop_limit;
	newnp->rcv_flowinfo = ip6_flowinfo(ipv6_hdr(skb));
	if (inet6_test_bit(REPFLOW, sk))
		newnp->flow_label = ip6_flowlabel(ipv6_hdr(skb));

	/* Set ToS of the new socket based upon the value of incoming SYN.
	 * ECT bits are set later in tcp_init_transfer().
	 */
	if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_reflect_tos))
		newnp->tclass = tcp_rsk(req)->syn_tos & ~INET_ECN_MASK;

	/* Clone native IPv6 options from listening socket (if any)

	   Yes, keeping reference count would be much more clever,
	   but we make one more one thing there: reattach optmem
	   to newsk.
	 */
	opt = ireq->ipv6_opt;
	if (!opt)
		opt = rcu_dereference(np->opt);
	if (opt) {
		opt = ipv6_dup_options(newsk, opt);
		RCU_INIT_POINTER(newnp->opt, opt);
	}
	inet_csk(newsk)->icsk_ext_hdr_len = 0;
	if (opt)
		inet_csk(newsk)->icsk_ext_hdr_len = opt->opt_nflen +
						    opt->opt_flen;

	tcp_ca_openreq_child(newsk, dst);

	tcp_sync_mss(newsk, dst_mtu(dst));
	newtp->advmss = tcp_mss_clamp(tcp_sk(sk), dst_metric_advmss(dst));

	tcp_initialize_rcv_mss(newsk);

	newinet->inet_daddr = newinet->inet_saddr = LOOPBACK4_IPV6;
	newinet->inet_rcv_saddr = LOOPBACK4_IPV6;

#ifdef CONFIG_TCP_MD5SIG
	l3index = l3mdev_master_ifindex_by_index(sock_net(sk), ireq->ir_iif);

	if (!tcp_rsk_used_ao(req)) {
		/* Copy over the MD5 key from the original socket */
		key = tcp_v6_md5_do_lookup(sk, &newsk->sk_v6_daddr, l3index);
		if (key) {
			const union tcp_md5_addr *addr;

			addr = (union tcp_md5_addr *)&newsk->sk_v6_daddr;
			if (tcp_md5_key_copy(newsk, addr, AF_INET6, 128, l3index, key)) {
				inet_csk_prepare_forced_close(newsk);
				tcp_done(newsk);
				goto out;
			}
		}
	}
#endif
#ifdef CONFIG_TCP_AO
	/* Copy over tcp_ao_info if any */
	if (tcp_ao_copy_all_matching(sk, newsk, req, skb, AF_INET6))
		goto out; /* OOM */
#endif

	if (__inet_inherit_port(sk, newsk) < 0) {
		inet_csk_prepare_forced_close(newsk);
		tcp_done(newsk);
		goto out;
	}
	*own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash),
				       &found_dup_sk);
	if (*own_req) {
		tcp_move_syn(newtp, req);

		/* Clone pktoptions received with SYN, if we own the req */
		if (ireq->pktopts) {
			newnp->pktoptions = skb_clone_and_charge_r(ireq->pktopts, newsk);
			consume_skb(ireq->pktopts);
			ireq->pktopts = NULL;
			if (newnp->pktoptions)
				tcp_v6_restore_cb(newnp->pktoptions);
		}
	} else {
		if (!req_unhash && found_dup_sk) {
			/* This code path should only be executed in the
			 * syncookie case only
			 */
			bh_unlock_sock(newsk);
			sock_put(newsk);
			newsk = NULL;
		}
	}

	return newsk;

out_overflow:
	__NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
out_nonewsk:
	dst_release(dst);
out:
	tcp_listendrop(sk);
	return NULL;
}

INDIRECT_CALLABLE_DECLARE(struct dst_entry *ipv4_dst_check(struct dst_entry *,
							   u32));
/* The socket must have it's spinlock held when we get
 * here, unless it is a TCP_LISTEN socket.
 *
 * We have a potential double-lock case here, so even when
 * doing backlog processing we use the BH locking scheme.
 * This is because we cannot sleep with the original spinlock
 * held.
 */
INDIRECT_CALLABLE_SCOPE
int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
{
	struct ipv6_pinfo *np = tcp_inet6_sk(sk);
	struct sk_buff *opt_skb = NULL;
	enum skb_drop_reason reason;
	struct tcp_sock *tp;

	/* Imagine: socket is IPv6. IPv4 packet arrives,
	   goes to IPv4 receive handler and backlogged.
	   From backlog it always goes here. Kerboom...
	   Fortunately, tcp_rcv_established and rcv_established
	   handle them correctly, but it is not case with
	   tcp_v6_hnd_req and tcp_v6_send_reset().   --ANK
	 */

	if (skb->protocol == htons(ETH_P_IP))
		return tcp_v4_do_rcv(sk, skb);

	/*
	 *	socket locking is here for SMP purposes as backlog rcv
	 *	is currently called with bh processing disabled.
	 */

	/* Do Stevens' IPV6_PKTOPTIONS.

	   Yes, guys, it is the only place in our code, where we
	   may make it not affecting IPv4.
	   The rest of code is protocol independent,
	   and I do not like idea to uglify IPv4.

	   Actually, all the idea behind IPV6_PKTOPTIONS
	   looks not very well thought. For now we latch
	   options, received in the last packet, enqueued
	   by tcp. Feel free to propose better solution.
					       --ANK (980728)
	 */
	if (np->rxopt.all)
		opt_skb = skb_clone_and_charge_r(skb, sk);

	if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
		struct dst_entry *dst;

		dst = rcu_dereference_protected(sk->sk_rx_dst,
						lockdep_sock_is_held(sk));

		sock_rps_save_rxhash(sk, skb);
		sk_mark_napi_id(sk, skb);
		if (dst) {
			if (sk->sk_rx_dst_ifindex != skb->skb_iif ||
			    INDIRECT_CALL_1(dst->ops->check, ip6_dst_check,
					    dst, sk->sk_rx_dst_cookie) == NULL) {
				RCU_INIT_POINTER(sk->sk_rx_dst, NULL);
				dst_release(dst);
			}
		}

		tcp_rcv_established(sk, skb);
		if (opt_skb)
			goto ipv6_pktoptions;
		return 0;
	}

	if (tcp_checksum_complete(skb))
		goto csum_err;

	if (sk->sk_state == TCP_LISTEN) {
		struct sock *nsk = tcp_v6_cookie_check(sk, skb);

		if (nsk != sk) {
			if (nsk) {
				reason = tcp_child_process(sk, nsk, skb);
				if (reason)
					goto reset;
			}
			if (opt_skb)
				__kfree_skb(opt_skb);
			return 0;
		}
	} else
		sock_rps_save_rxhash(sk, skb);

	reason = tcp_rcv_state_process(sk, skb);
	if (reason)
		goto reset;
	if (opt_skb)
		goto ipv6_pktoptions;
	return 0;

reset:
	tcp_v6_send_reset(sk, skb);
discard:
	if (opt_skb)
		__kfree_skb(opt_skb);
	kfree_skb_reason(skb, reason);
	return 0;
csum_err:
	reason = SKB_DROP_REASON_TCP_CSUM;
	trace_tcp_bad_csum(skb);
	TCP_INC_STATS(sock_net(sk), TCP_MIB_CSUMERRORS);
	TCP_INC_STATS(sock_net(sk), TCP_MIB_INERRS);
	goto discard;


ipv6_pktoptions:
	/* Do you ask, what is it?

	   1. skb was enqueued by tcp.
	   2. skb is added to tail of read queue, rather than out of order.
	   3. socket is not in passive state.
	   4. Finally, it really contains options, which user wants to receive.
	 */
	tp = tcp_sk(sk);
	if (TCP_SKB_CB(opt_skb)->end_seq == tp->rcv_nxt &&
	    !((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))) {
		if (np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo)
			WRITE_ONCE(np->mcast_oif, tcp_v6_iif(opt_skb));
		if (np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim)
			WRITE_ONCE(np->mcast_hops,
				   ipv6_hdr(opt_skb)->hop_limit);
		if (np->rxopt.bits.rxflow || np->rxopt.bits.rxtclass)
			np->rcv_flowinfo = ip6_flowinfo(ipv6_hdr(opt_skb));
		if (inet6_test_bit(REPFLOW, sk))
			np->flow_label = ip6_flowlabel(ipv6_hdr(opt_skb));
		if (ipv6_opt_accepted(sk, opt_skb, &TCP_SKB_CB(opt_skb)->header.h6)) {
			tcp_v6_restore_cb(opt_skb);
			opt_skb = xchg(&np->pktoptions, opt_skb);
		} else {
			__kfree_skb(opt_skb);
			opt_skb = xchg(&np->pktoptions, NULL);
		}
	}

	consume_skb(opt_skb);
	return 0;
}

static void tcp_v6_fill_cb(struct sk_buff *skb, const struct ipv6hdr *hdr,
			   const struct tcphdr *th)
{
	/* This is tricky: we move IP6CB at its correct location into
	 * TCP_SKB_CB(). It must be done after xfrm6_policy_check(), because
	 * _decode_session6() uses IP6CB().
	 * barrier() makes sure compiler won't play aliasing games.
	 */
	memmove(&TCP_SKB_CB(skb)->header.h6, IP6CB(skb),
		sizeof(struct inet6_skb_parm));
	barrier();

	TCP_SKB_CB(skb)->seq = ntohl(th->seq);
	TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
				    skb->len - th->doff*4);
	TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
	TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th);
	TCP_SKB_CB(skb)->ip_dsfield = ipv6_get_dsfield(hdr);
	TCP_SKB_CB(skb)->sacked = 0;
	TCP_SKB_CB(skb)->has_rxtstamp =
			skb->tstamp || skb_hwtstamps(skb)->hwtstamp;
}

INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
{
	enum skb_drop_reason drop_reason;
	int sdif = inet6_sdif(skb);
	int dif = inet6_iif(skb);
	const struct tcphdr *th;
	const struct ipv6hdr *hdr;
	bool refcounted;
	struct sock *sk;
	int ret;
	u32 isn;
	struct net *net = dev_net(skb->dev);

	drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
	if (skb->pkt_type != PACKET_HOST)
		goto discard_it;

	/*
	 *	Count it even if it's bad.
	 */
	__TCP_INC_STATS(net, TCP_MIB_INSEGS);

	if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
		goto discard_it;

	th = (const struct tcphdr *)skb->data;

	if (unlikely(th->doff < sizeof(struct tcphdr) / 4)) {
		drop_reason = SKB_DROP_REASON_PKT_TOO_SMALL;
		goto bad_packet;
	}
	if (!pskb_may_pull(skb, th->doff*4))
		goto discard_it;

	if (skb_checksum_init(skb, IPPROTO_TCP, ip6_compute_pseudo))
		goto csum_error;

	th = (const struct tcphdr *)skb->data;
	hdr = ipv6_hdr(skb);

lookup:
	sk = __inet6_lookup_skb(net->ipv4.tcp_death_row.hashinfo, skb, __tcp_hdrlen(th),
				th->source, th->dest, inet6_iif(skb), sdif,
				&refcounted);
	if (!sk)
		goto no_tcp_socket;

	if (sk->sk_state == TCP_TIME_WAIT)
		goto do_time_wait;

	if (sk->sk_state == TCP_NEW_SYN_RECV) {
		struct request_sock *req = inet_reqsk(sk);
		bool req_stolen = false;
		struct sock *nsk;

		sk = req->rsk_listener;
		if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
			drop_reason = SKB_DROP_REASON_XFRM_POLICY;
		else
			drop_reason = tcp_inbound_hash(sk, req, skb,
						       &hdr->saddr, &hdr->daddr,
						       AF_INET6, dif, sdif);
		if (drop_reason) {
			sk_drops_add(sk, skb);
			reqsk_put(req);
			goto discard_it;
		}
		if (tcp_checksum_complete(skb)) {
			reqsk_put(req);
			goto csum_error;
		}
		if (unlikely(sk->sk_state != TCP_LISTEN)) {
			nsk = reuseport_migrate_sock(sk, req_to_sk(req), skb);
			if (!nsk) {
				inet_csk_reqsk_queue_drop_and_put(sk, req);
				goto lookup;
			}
			sk = nsk;
			/* reuseport_migrate_sock() has already held one sk_refcnt
			 * before returning.
			 */
		} else {
			sock_hold(sk);
		}
		refcounted = true;
		nsk = NULL;
		if (!tcp_filter(sk, skb)) {
			th = (const struct tcphdr *)skb->data;
			hdr = ipv6_hdr(skb);
			tcp_v6_fill_cb(skb, hdr, th);
			nsk = tcp_check_req(sk, skb, req, false, &req_stolen);
		} else {
			drop_reason = SKB_DROP_REASON_SOCKET_FILTER;
		}
		if (!nsk) {
			reqsk_put(req);
			if (req_stolen) {
				/* Another cpu got exclusive access to req
				 * and created a full blown socket.
				 * Try to feed this packet to this socket
				 * instead of discarding it.
				 */
				tcp_v6_restore_cb(skb);
				sock_put(sk);
				goto lookup;
			}
			goto discard_and_relse;
		}
		nf_reset_ct(skb);
		if (nsk == sk) {
			reqsk_put(req);
			tcp_v6_restore_cb(skb);
		} else {
			drop_reason = tcp_child_process(sk, nsk, skb);
			if (drop_reason) {
				tcp_v6_send_reset(nsk, skb);
				goto discard_and_relse;
			}
			sock_put(sk);
			return 0;
		}
	}

process:
	if (static_branch_unlikely(&ip6_min_hopcount)) {
		/* min_hopcount can be changed concurrently from do_ipv6_setsockopt() */
		if (unlikely(hdr->hop_limit < READ_ONCE(tcp_inet6_sk(sk)->min_hopcount))) {
			__NET_INC_STATS(net, LINUX_MIB_TCPMINTTLDROP);
			drop_reason = SKB_DROP_REASON_TCP_MINTTL;
			goto discard_and_relse;
		}
	}

	if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb)) {
		drop_reason = SKB_DROP_REASON_XFRM_POLICY;
		goto discard_and_relse;
	}

	drop_reason = tcp_inbound_hash(sk, NULL, skb, &hdr->saddr, &hdr->daddr,
				       AF_INET6, dif, sdif);
	if (drop_reason)
		goto discard_and_relse;

	nf_reset_ct(skb);

	if (tcp_filter(sk, skb)) {
		drop_reason = SKB_DROP_REASON_SOCKET_FILTER;
		goto discard_and_relse;
	}
	th = (const struct tcphdr *)skb->data;
	hdr = ipv6_hdr(skb);
	tcp_v6_fill_cb(skb, hdr, th);

	skb->dev = NULL;

	if (sk->sk_state == TCP_LISTEN) {
		ret = tcp_v6_do_rcv(sk, skb);
		goto put_and_return;
	}

	sk_incoming_cpu_update(sk);

	bh_lock_sock_nested(sk);
	tcp_segs_in(tcp_sk(sk), skb);
	ret = 0;
	if (!sock_owned_by_user(sk)) {
		ret = tcp_v6_do_rcv(sk, skb);
	} else {
		if (tcp_add_backlog(sk, skb, &drop_reason))
			goto discard_and_relse;
	}
	bh_unlock_sock(sk);
put_and_return:
	if (refcounted)
		sock_put(sk);
	return ret ? -1 : 0;

no_tcp_socket:
	drop_reason = SKB_DROP_REASON_NO_SOCKET;
	if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
		goto discard_it;

	tcp_v6_fill_cb(skb, hdr, th);

	if (tcp_checksum_complete(skb)) {
csum_error:
		drop_reason = SKB_DROP_REASON_TCP_CSUM;
		trace_tcp_bad_csum(skb);
		__TCP_INC_STATS(net, TCP_MIB_CSUMERRORS);
bad_packet:
		__TCP_INC_STATS(net, TCP_MIB_INERRS);
	} else {
		tcp_v6_send_reset(NULL, skb);
	}

discard_it:
	SKB_DR_OR(drop_reason, NOT_SPECIFIED);
	kfree_skb_reason(skb, drop_reason);
	return 0;

discard_and_relse:
	sk_drops_add(sk, skb);
	if (refcounted)
		sock_put(sk);
	goto discard_it;

do_time_wait:
	if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
		drop_reason = SKB_DROP_REASON_XFRM_POLICY;
		inet_twsk_put(inet_twsk(sk));
		goto discard_it;
	}

	tcp_v6_fill_cb(skb, hdr, th);

	if (tcp_checksum_complete(skb)) {
		inet_twsk_put(inet_twsk(sk));
		goto csum_error;
	}

	switch (tcp_timewait_state_process(inet_twsk(sk), skb, th, &isn)) {
	case TCP_TW_SYN:
	{
		struct sock *sk2;

		sk2 = inet6_lookup_listener(net, net->ipv4.tcp_death_row.hashinfo,
					    skb, __tcp_hdrlen(th),
					    &ipv6_hdr(skb)->saddr, th->source,
					    &ipv6_hdr(skb)->daddr,
					    ntohs(th->dest),
					    tcp_v6_iif_l3_slave(skb),
					    sdif);
		if (sk2) {
			struct inet_timewait_sock *tw = inet_twsk(sk);
			inet_twsk_deschedule_put(tw);
			sk = sk2;
			tcp_v6_restore_cb(skb);
			refcounted = false;
			__this_cpu_write(tcp_tw_isn, isn);
			goto process;
		}
	}
		/* to ACK */
		fallthrough;
	case TCP_TW_ACK:
		tcp_v6_timewait_ack(sk, skb);
		break;
	case TCP_TW_RST:
		tcp_v6_send_reset(sk, skb);
		inet_twsk_deschedule_put(inet_twsk(sk));
		goto discard_it;
	case TCP_TW_SUCCESS:
		;
	}
	goto discard_it;
}

void tcp_v6_early_demux(struct sk_buff *skb)
{
	struct net *net = dev_net(skb->dev);
	const struct ipv6hdr *hdr;
	const struct tcphdr *th;
	struct sock *sk;

	if (skb->pkt_type != PACKET_HOST)
		return;

	if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct tcphdr)))
		return;

	hdr = ipv6_hdr(skb);
	th = tcp_hdr(skb);

	if (th->doff < sizeof(struct tcphdr) / 4)
		return;

	/* Note : We use inet6_iif() here, not tcp_v6_iif() */
	sk = __inet6_lookup_established(net, net->ipv4.tcp_death_row.hashinfo,
					&hdr->saddr, th->source,
					&hdr->daddr, ntohs(th->dest),
					inet6_iif(skb), inet6_sdif(skb));
	if (sk) {
		skb->sk = sk;
		skb->destructor = sock_edemux;
		if (sk_fullsock(sk)) {
			struct dst_entry *dst = rcu_dereference(sk->sk_rx_dst);

			if (dst)
				dst = dst_check(dst, sk->sk_rx_dst_cookie);
			if (dst &&
			    sk->sk_rx_dst_ifindex == skb->skb_iif)
				skb_dst_set_noref(skb, dst);
		}
	}
}

static struct timewait_sock_ops tcp6_timewait_sock_ops = {
	.twsk_obj_size	= sizeof(struct tcp6_timewait_sock),
	.twsk_unique	= tcp_twsk_unique,
	.twsk_destructor = tcp_twsk_destructor,
};

INDIRECT_CALLABLE_SCOPE void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb)
{
	__tcp_v6_send_check(skb, &sk->sk_v6_rcv_saddr, &sk->sk_v6_daddr);
}

const struct inet_connection_sock_af_ops ipv6_specific = {
	.queue_xmit	   = inet6_csk_xmit,
	.send_check	   = tcp_v6_send_check,
	.rebuild_header	   = inet6_sk_rebuild_header,
	.sk_rx_dst_set	   = inet6_sk_rx_dst_set,
	.conn_request	   = tcp_v6_conn_request,
	.syn_recv_sock	   = tcp_v6_syn_recv_sock,
	.net_header_len	   = sizeof(struct ipv6hdr),
	.setsockopt	   = ipv6_setsockopt,
	.getsockopt	   = ipv6_getsockopt,
	.addr2sockaddr	   = inet6_csk_addr2sockaddr,
	.sockaddr_len	   = sizeof(struct sockaddr_in6),
	.mtu_reduced	   = tcp_v6_mtu_reduced,
};

#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
static const struct tcp_sock_af_ops tcp_sock_ipv6_specific = {
#ifdef CONFIG_TCP_MD5SIG
	.md5_lookup	=	tcp_v6_md5_lookup,
	.calc_md5_hash	=	tcp_v6_md5_hash_skb,
	.md5_parse	=	tcp_v6_parse_md5_keys,
#endif
#ifdef CONFIG_TCP_AO
	.ao_lookup	=	tcp_v6_ao_lookup,
	.calc_ao_hash	=	tcp_v6_ao_hash_skb,
	.ao_parse	=	tcp_v6_parse_ao,
	.ao_calc_key_sk	=	tcp_v6_ao_calc_key_sk,
#endif
};
#endif

/*
 *	TCP over IPv4 via INET6 API
 */
static const struct inet_connection_sock_af_ops ipv6_mapped = {
	.queue_xmit	   = ip_queue_xmit,
	.send_check	   = tcp_v4_send_check,
	.rebuild_header	   = inet_sk_rebuild_header,
	.sk_rx_dst_set	   = inet_sk_rx_dst_set,
	.conn_request	   = tcp_v6_conn_request,
	.syn_recv_sock	   = tcp_v6_syn_recv_sock,
	.net_header_len	   = sizeof(struct iphdr),
	.setsockopt	   = ipv6_setsockopt,
	.getsockopt	   = ipv6_getsockopt,
	.addr2sockaddr	   = inet6_csk_addr2sockaddr,
	.sockaddr_len	   = sizeof(struct sockaddr_in6),
	.mtu_reduced	   = tcp_v4_mtu_reduced,
};

#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
static const struct tcp_sock_af_ops tcp_sock_ipv6_mapped_specific = {
#ifdef CONFIG_TCP_MD5SIG
	.md5_lookup	=	tcp_v4_md5_lookup,
	.calc_md5_hash	=	tcp_v4_md5_hash_skb,
	.md5_parse	=	tcp_v6_parse_md5_keys,
#endif
#ifdef CONFIG_TCP_AO
	.ao_lookup	=	tcp_v6_ao_lookup,
	.calc_ao_hash	=	tcp_v4_ao_hash_skb,
	.ao_parse	=	tcp_v6_parse_ao,
	.ao_calc_key_sk	=	tcp_v4_ao_calc_key_sk,
#endif
};
#endif

/* NOTE: A lot of things set to zero explicitly by call to
 *       sk_alloc() so need not be done here.
 */
static int tcp_v6_init_sock(struct sock *sk)
{
	struct inet_connection_sock *icsk = inet_csk(sk);

	tcp_init_sock(sk);

	icsk->icsk_af_ops = &ipv6_specific;

#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
	tcp_sk(sk)->af_specific = &tcp_sock_ipv6_specific;
#endif

	return 0;
}

#ifdef CONFIG_PROC_FS
/* Proc filesystem TCPv6 sock list dumping. */
static void get_openreq6(struct seq_file *seq,
			 const struct request_sock *req, int i)
{
	long ttd = req->rsk_timer.expires - jiffies;
	const struct in6_addr *src = &inet_rsk(req)->ir_v6_loc_addr;
	const struct in6_addr *dest = &inet_rsk(req)->ir_v6_rmt_addr;

	if (ttd < 0)
		ttd = 0;

	seq_printf(seq,
		   "%4d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
		   "%02X %08X:%08X %02X:%08lX %08X %5u %8d %d %d %pK\n",
		   i,
		   src->s6_addr32[0], src->s6_addr32[1],
		   src->s6_addr32[2], src->s6_addr32[3],
		   inet_rsk(req)->ir_num,
		   dest->s6_addr32[0], dest->s6_addr32[1],
		   dest->s6_addr32[2], dest->s6_addr32[3],
		   ntohs(inet_rsk(req)->ir_rmt_port),
		   TCP_SYN_RECV,
		   0, 0, /* could print option size, but that is af dependent. */
		   1,   /* timers active (only the expire timer) */
		   jiffies_to_clock_t(ttd),
		   req->num_timeout,
		   from_kuid_munged(seq_user_ns(seq),
				    sock_i_uid(req->rsk_listener)),
		   0,  /* non standard timer */
		   0, /* open_requests have no inode */
		   0, req);
}

static void get_tcp6_sock(struct seq_file *seq, struct sock *sp, int i)
{
	const struct in6_addr *dest, *src;
	__u16 destp, srcp;
	int timer_active;
	unsigned long timer_expires;
	const struct inet_sock *inet = inet_sk(sp);
	const struct tcp_sock *tp = tcp_sk(sp);
	const struct inet_connection_sock *icsk = inet_csk(sp);
	const struct fastopen_queue *fastopenq = &icsk->icsk_accept_queue.fastopenq;
	int rx_queue;
	int state;

	dest  = &sp->sk_v6_daddr;
	src   = &sp->sk_v6_rcv_saddr;
	destp = ntohs(inet->inet_dport);
	srcp  = ntohs(inet->inet_sport);

	if (icsk->icsk_pending == ICSK_TIME_RETRANS ||
	    icsk->icsk_pending == ICSK_TIME_REO_TIMEOUT ||
	    icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) {
		timer_active	= 1;
		timer_expires	= icsk->icsk_timeout;
	} else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
		timer_active	= 4;
		timer_expires	= icsk->icsk_timeout;
	} else if (timer_pending(&sp->sk_timer)) {
		timer_active	= 2;
		timer_expires	= sp->sk_timer.expires;
	} else {
		timer_active	= 0;
		timer_expires = jiffies;
	}

	state = inet_sk_state_load(sp);
	if (state == TCP_LISTEN)
		rx_queue = READ_ONCE(sp->sk_ack_backlog);
	else
		/* Because we don't lock the socket,
		 * we might find a transient negative value.
		 */
		rx_queue = max_t(int, READ_ONCE(tp->rcv_nxt) -
				      READ_ONCE(tp->copied_seq), 0);

	seq_printf(seq,
		   "%4d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
		   "%02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %lu %lu %u %u %d\n",
		   i,
		   src->s6_addr32[0], src->s6_addr32[1],
		   src->s6_addr32[2], src->s6_addr32[3], srcp,
		   dest->s6_addr32[0], dest->s6_addr32[1],
		   dest->s6_addr32[2], dest->s6_addr32[3], destp,
		   state,
		   READ_ONCE(tp->write_seq) - tp->snd_una,
		   rx_queue,
		   timer_active,
		   jiffies_delta_to_clock_t(timer_expires - jiffies),
		   icsk->icsk_retransmits,
		   from_kuid_munged(seq_user_ns(seq), sock_i_uid(sp)),
		   icsk->icsk_probes_out,
		   sock_i_ino(sp),
		   refcount_read(&sp->sk_refcnt), sp,
		   jiffies_to_clock_t(icsk->icsk_rto),
		   jiffies_to_clock_t(icsk->icsk_ack.ato),
		   (icsk->icsk_ack.quick << 1) | inet_csk_in_pingpong_mode(sp),
		   tcp_snd_cwnd(tp),
		   state == TCP_LISTEN ?
			fastopenq->max_qlen :
			(tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh)
		   );
}

static void get_timewait6_sock(struct seq_file *seq,
			       struct inet_timewait_sock *tw, int i)
{
	long delta = tw->tw_timer.expires - jiffies;
	const struct in6_addr *dest, *src;
	__u16 destp, srcp;

	dest = &tw->tw_v6_daddr;
	src  = &tw->tw_v6_rcv_saddr;
	destp = ntohs(tw->tw_dport);
	srcp  = ntohs(tw->tw_sport);

	seq_printf(seq,
		   "%4d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
		   "%02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK\n",
		   i,
		   src->s6_addr32[0], src->s6_addr32[1],
		   src->s6_addr32[2], src->s6_addr32[3], srcp,
		   dest->s6_addr32[0], dest->s6_addr32[1],
		   dest->s6_addr32[2], dest->s6_addr32[3], destp,
		   tw->tw_substate, 0, 0,
		   3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,
		   refcount_read(&tw->tw_refcnt), tw);
}

static int tcp6_seq_show(struct seq_file *seq, void *v)
{
	struct tcp_iter_state *st;
	struct sock *sk = v;

	if (v == SEQ_START_TOKEN) {
		seq_puts(seq,
			 "  sl  "
			 "local_address                         "
			 "remote_address                        "
			 "st tx_queue rx_queue tr tm->when retrnsmt"
			 "   uid  timeout inode\n");
		goto out;
	}
	st = seq->private;

	if (sk->sk_state == TCP_TIME_WAIT)
		get_timewait6_sock(seq, v, st->num);
	else if (sk->sk_state == TCP_NEW_SYN_RECV)
		get_openreq6(seq, v, st->num);
	else
		get_tcp6_sock(seq, v, st->num);
out:
	return 0;
}

static const struct seq_operations tcp6_seq_ops = {
	.show		= tcp6_seq_show,
	.start		= tcp_seq_start,
	.next		= tcp_seq_next,
	.stop		= tcp_seq_stop,
};

static struct tcp_seq_afinfo tcp6_seq_afinfo = {
	.family		= AF_INET6,
};

int __net_init tcp6_proc_init(struct net *net)
{
	if (!proc_create_net_data("tcp6", 0444, net->proc_net, &tcp6_seq_ops,
			sizeof(struct tcp_iter_state), &tcp6_seq_afinfo))
		return -ENOMEM;
	return 0;
}

void tcp6_proc_exit(struct net *net)
{
	remove_proc_entry("tcp6", net->proc_net);
}
#endif

struct proto tcpv6_prot = {
	.name			= "TCPv6",
	.owner			= THIS_MODULE,
	.close			= tcp_close,
	.pre_connect		= tcp_v6_pre_connect,
	.connect		= tcp_v6_connect,
	.disconnect		= tcp_disconnect,
	.accept			= inet_csk_accept,
	.ioctl			= tcp_ioctl,
	.init			= tcp_v6_init_sock,
	.destroy		= tcp_v4_destroy_sock,
	.shutdown		= tcp_shutdown,
	.setsockopt		= tcp_setsockopt,
	.getsockopt		= tcp_getsockopt,
	.bpf_bypass_getsockopt	= tcp_bpf_bypass_getsockopt,
	.keepalive		= tcp_set_keepalive,
	.recvmsg		= tcp_recvmsg,
	.sendmsg		= tcp_sendmsg,
	.splice_eof		= tcp_splice_eof,
	.backlog_rcv		= tcp_v6_do_rcv,
	.release_cb		= tcp_release_cb,
	.hash			= inet6_hash,
	.unhash			= inet_unhash,
	.get_port		= inet_csk_get_port,
	.put_port		= inet_put_port,
#ifdef CONFIG_BPF_SYSCALL
	.psock_update_sk_prot	= tcp_bpf_update_proto,
#endif
	.enter_memory_pressure	= tcp_enter_memory_pressure,
	.leave_memory_pressure	= tcp_leave_memory_pressure,
	.stream_memory_free	= tcp_stream_memory_free,
	.sockets_allocated	= &tcp_sockets_allocated,

	.memory_allocated	= &tcp_memory_allocated,
	.per_cpu_fw_alloc	= &tcp_memory_per_cpu_fw_alloc,

	.memory_pressure	= &tcp_memory_pressure,
	.orphan_count		= &tcp_orphan_count,
	.sysctl_mem		= sysctl_tcp_mem,
	.sysctl_wmem_offset	= offsetof(struct net, ipv4.sysctl_tcp_wmem),
	.sysctl_rmem_offset	= offsetof(struct net, ipv4.sysctl_tcp_rmem),
	.max_header		= MAX_TCP_HEADER,
	.obj_size		= sizeof(struct tcp6_sock),
	.ipv6_pinfo_offset = offsetof(struct tcp6_sock, inet6),
	.slab_flags		= SLAB_TYPESAFE_BY_RCU,
	.twsk_prot		= &tcp6_timewait_sock_ops,
	.rsk_prot		= &tcp6_request_sock_ops,
	.h.hashinfo		= NULL,
	.no_autobind		= true,
	.diag_destroy		= tcp_abort,
};
EXPORT_SYMBOL_GPL(tcpv6_prot);


static struct inet_protosw tcpv6_protosw = {
	.type		=	SOCK_STREAM,
	.protocol	=	IPPROTO_TCP,
	.prot		=	&tcpv6_prot,
	.ops		=	&inet6_stream_ops,
	.flags		=	INET_PROTOSW_PERMANENT |
				INET_PROTOSW_ICSK,
};

static int __net_init tcpv6_net_init(struct net *net)
{
	return inet_ctl_sock_create(&net->ipv6.tcp_sk, PF_INET6,
				    SOCK_RAW, IPPROTO_TCP, net);
}

static void __net_exit tcpv6_net_exit(struct net *net)
{
	inet_ctl_sock_destroy(net->ipv6.tcp_sk);
}

static struct pernet_operations tcpv6_net_ops = {
	.init	    = tcpv6_net_init,
	.exit	    = tcpv6_net_exit,
};

int __init tcpv6_init(void)
{
	int ret;

	net_hotdata.tcpv6_protocol = (struct inet6_protocol) {
		.handler     = tcp_v6_rcv,
		.err_handler = tcp_v6_err,
		.flags	     = INET6_PROTO_NOPOLICY | INET6_PROTO_FINAL,
	};
	ret = inet6_add_protocol(&net_hotdata.tcpv6_protocol, IPPROTO_TCP);
	if (ret)
		goto out;

	/* register inet6 protocol */
	ret = inet6_register_protosw(&tcpv6_protosw);
	if (ret)
		goto out_tcpv6_protocol;

	ret = register_pernet_subsys(&tcpv6_net_ops);
	if (ret)
		goto out_tcpv6_protosw;

	ret = mptcpv6_init();
	if (ret)
		goto out_tcpv6_pernet_subsys;

out:
	return ret;

out_tcpv6_pernet_subsys:
	unregister_pernet_subsys(&tcpv6_net_ops);
out_tcpv6_protosw:
	inet6_unregister_protosw(&tcpv6_protosw);
out_tcpv6_protocol:
	inet6_del_protocol(&net_hotdata.tcpv6_protocol, IPPROTO_TCP);
	goto out;
}

void tcpv6_exit(void)
{
	unregister_pernet_subsys(&tcpv6_net_ops);
	inet6_unregister_protosw(&tcpv6_protosw);
	inet6_del_protocol(&net_hotdata.tcpv6_protocol, IPPROTO_TCP);
}