net/ipv6/tcp_ipv6.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      TCP over IPv6
   4  *      Linux INET6 implementation
   5  *
   6  *      Authors:
   7  *      Pedro Roque             <roque@di.fc.ul.pt>
   8  *
   9  *      Based on:
  10  *      linux/net/ipv4/tcp.c
  11  *      linux/net/ipv4/tcp_input.c
  12  *      linux/net/ipv4/tcp_output.c
  13  *
  14  *      Fixes:
  15  *      Hideaki YOSHIFUJI       :       sin6_scope_id support
  16  *      YOSHIFUJI Hideaki @USAGI and:   Support IPV6_V6ONLY socket option, which
  17  *      Alexey Kuznetsov                allow both IPv4 and IPv6 sockets to bind
  18  *                                      a single port at the same time.
  19  *      YOSHIFUJI Hideaki @USAGI:       convert /proc/net/tcp6 to seq_file.
  20  */
  21
  22 #include <linux/bottom_half.h>
  23 #include <linux/module.h>
  24 #include <linux/errno.h>
  25 #include <linux/types.h>
  26 #include <linux/socket.h>
  27 #include <linux/sockios.h>
  28 #include <linux/net.h>
  29 #include <linux/jiffies.h>
  30 #include <linux/in.h>
  31 #include <linux/in6.h>
  32 #include <linux/netdevice.h>
  33 #include <linux/init.h>
  34 #include <linux/jhash.h>
  35 #include <linux/ipsec.h>
  36 #include <linux/times.h>
  37 #include <linux/slab.h>
  38 #include <linux/uaccess.h>
  39 #include <linux/ipv6.h>
  40 #include <linux/icmpv6.h>
  41 #include <linux/random.h>
  42 #include <linux/indirect_call_wrapper.h>
  43
  44 #include <net/tcp.h>
  45 #include <net/ndisc.h>
  46 #include <net/inet6_hashtables.h>
  47 #include <net/inet6_connection_sock.h>
  48 #include <net/ipv6.h>
  49 #include <net/transp_v6.h>
  50 #include <net/addrconf.h>
  51 #include <net/ip6_route.h>
  52 #include <net/ip6_checksum.h>
  53 #include <net/inet_ecn.h>
  54 #include <net/protocol.h>
  55 #include <net/xfrm.h>
  56 #include <net/snmp.h>
  57 #include <net/dsfield.h>
  58 #include <net/timewait_sock.h>
  59 #include <net/inet_common.h>
  60 #include <net/secure_seq.h>
  61 #include <net/busy_poll.h>
  62
  63 #include <linux/proc_fs.h>
  64 #include <linux/seq_file.h>
  65
  66 #include <crypto/hash.h>
  67 #include <linux/scatterlist.h>
  68
  69 #include <trace/events/tcp.h>
  70
  71 static void     tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb);
  72 static void     tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
  73                                       struct request_sock *req);
  74
  75 static int      tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb);
  76
  77 static const struct inet_connection_sock_af_ops ipv6_mapped;
  78 const struct inet_connection_sock_af_ops ipv6_specific;
  79 #ifdef CONFIG_TCP_MD5SIG
  80 static const struct tcp_sock_af_ops tcp_sock_ipv6_specific;
  81 static const struct tcp_sock_af_ops tcp_sock_ipv6_mapped_specific;
  82 #else
  83 static struct tcp_md5sig_key *tcp_v6_md5_do_lookup(const struct sock *sk,
  84                                                    const struct in6_addr *addr,
  85                                                    int l3index)
  86 {
  87         return NULL;
  88 }
  89 #endif
  90
  91 /* Helper returning the inet6 address from a given tcp socket.
  92  * It can be used in TCP stack instead of inet6_sk(sk).
  93  * This avoids a dereference and allow compiler optimizations.
  94  * It is a specialized version of inet6_sk_generic().
  95  */
  96 static struct ipv6_pinfo *tcp_inet6_sk(const struct sock *sk)
  97 {
  98         unsigned int offset = sizeof(struct tcp6_sock) - sizeof(struct ipv6_pinfo);
  99
 100         return (struct ipv6_pinfo *)(((u8 *)sk) + offset);
 101 }
 102
 103 static void inet6_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
 104 {
 105         struct dst_entry *dst = skb_dst(skb);
 106
 107         if (dst && dst_hold_safe(dst)) {
 108                 const struct rt6_info *rt = (const struct rt6_info *)dst;
 109
 110                 sk->sk_rx_dst = dst;
 111                 inet_sk(sk)->rx_dst_ifindex = skb->skb_iif;
 112                 tcp_inet6_sk(sk)->rx_dst_cookie = rt6_get_cookie(rt);
 113         }
 114 }
 115
 116 static u32 tcp_v6_init_seq(const struct sk_buff *skb)
 117 {
 118         return secure_tcpv6_seq(ipv6_hdr(skb)->daddr.s6_addr32,
 119                                 ipv6_hdr(skb)->saddr.s6_addr32,
 120                                 tcp_hdr(skb)->dest,
 121                                 tcp_hdr(skb)->source);
 122 }
 123
 124 static u32 tcp_v6_init_ts_off(const struct net *net, const struct sk_buff *skb)
 125 {
 126         return secure_tcpv6_ts_off(net, ipv6_hdr(skb)->daddr.s6_addr32,
 127                                    ipv6_hdr(skb)->saddr.s6_addr32);
 128 }
 129
 130 static int tcp_v6_pre_connect(struct sock *sk, struct sockaddr *uaddr,
 131                               int addr_len)
 132 {
 133         /* This check is replicated from tcp_v6_connect() and intended to
 134          * prevent BPF program called below from accessing bytes that are out
 135          * of the bound specified by user in addr_len.
 136          */
 137         if (addr_len < SIN6_LEN_RFC2133)
 138                 return -EINVAL;
 139
 140         sock_owned_by_me(sk);
 141
 142         return BPF_CGROUP_RUN_PROG_INET6_CONNECT(sk, uaddr);
 143 }
 144
 145 static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
 146                           int addr_len)
 147 {
 148         struct sockaddr_in6 *usin = (struct sockaddr_in6 *) uaddr;
 149         struct inet_sock *inet = inet_sk(sk);
 150         struct inet_connection_sock *icsk = inet_csk(sk);
 151         struct ipv6_pinfo *np = tcp_inet6_sk(sk);
 152         struct tcp_sock *tp = tcp_sk(sk);
 153         struct in6_addr *saddr = NULL, *final_p, final;
 154         struct ipv6_txoptions *opt;
 155         struct flowi6 fl6;
 156         struct dst_entry *dst;
 157         int addr_type;
 158         int err;
 159         struct inet_timewait_death_row *tcp_death_row = &sock_net(sk)->ipv4.tcp_death_row;
 160
 161         if (addr_len < SIN6_LEN_RFC2133)
 162                 return -EINVAL;
 163
 164         if (usin->sin6_family != AF_INET6)
 165                 return -EAFNOSUPPORT;
 166
 167         memset(&fl6, 0, sizeof(fl6));
 168
 169         if (np->sndflow) {
 170                 fl6.flowlabel = usin->sin6_flowinfo&IPV6_FLOWINFO_MASK;
 171                 IP6_ECN_flow_init(fl6.flowlabel);
 172                 if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
 173                         struct ip6_flowlabel *flowlabel;
 174                         flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 175                         if (IS_ERR(flowlabel))
 176                                 return -EINVAL;
 177                         fl6_sock_release(flowlabel);
 178                 }
 179         }
 180
 181         /*
 182          *      connect() to INADDR_ANY means loopback (BSD'ism).
 183          */
 184
 185         if (ipv6_addr_any(&usin->sin6_addr)) {
 186                 if (ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr))
 187                         ipv6_addr_set_v4mapped(htonl(INADDR_LOOPBACK),
 188                                                &usin->sin6_addr);
 189                 else
 190                         usin->sin6_addr = in6addr_loopback;
 191         }
 192
 193         addr_type = ipv6_addr_type(&usin->sin6_addr);
 194
 195         if (addr_type & IPV6_ADDR_MULTICAST)
 196                 return -ENETUNREACH;
 197
 198         if (addr_type&IPV6_ADDR_LINKLOCAL) {
 199                 if (addr_len >= sizeof(struct sockaddr_in6) &&
 200                     usin->sin6_scope_id) {
 201                         /* If interface is set while binding, indices
 202                          * must coincide.
 203                          */
 204                         if (!sk_dev_equal_l3scope(sk, usin->sin6_scope_id))
 205                                 return -EINVAL;
 206
 207                         sk->sk_bound_dev_if = usin->sin6_scope_id;
 208                 }
 209
 210                 /* Connect to link-local address requires an interface */
 211                 if (!sk->sk_bound_dev_if)
 212                         return -EINVAL;
 213         }
 214
 215         if (tp->rx_opt.ts_recent_stamp &&
 216             !ipv6_addr_equal(&sk->sk_v6_daddr, &usin->sin6_addr)) {
 217                 tp->rx_opt.ts_recent = 0;
 218                 tp->rx_opt.ts_recent_stamp = 0;
 219                 WRITE_ONCE(tp->write_seq, 0);
 220         }
 221
 222         sk->sk_v6_daddr = usin->sin6_addr;
 223         np->flow_label = fl6.flowlabel;
 224
 225         /*
 226          *      TCP over IPv4
 227          */
 228
 229         if (addr_type & IPV6_ADDR_MAPPED) {
 230                 u32 exthdrlen = icsk->icsk_ext_hdr_len;
 231                 struct sockaddr_in sin;
 232
 233                 if (__ipv6_only_sock(sk))
 234                         return -ENETUNREACH;
 235
 236                 sin.sin_family = AF_INET;
 237                 sin.sin_port = usin->sin6_port;
 238                 sin.sin_addr.s_addr = usin->sin6_addr.s6_addr32[3];
 239
 240                 icsk->icsk_af_ops = &ipv6_mapped;
 241                 if (sk_is_mptcp(sk))
 242                         mptcpv6_handle_mapped(sk, true);
 243                 sk->sk_backlog_rcv = tcp_v4_do_rcv;
 244 #ifdef CONFIG_TCP_MD5SIG
 245                 tp->af_specific = &tcp_sock_ipv6_mapped_specific;
 246 #endif
 247
 248                 err = tcp_v4_connect(sk, (struct sockaddr *)&sin, sizeof(sin));
 249
 250                 if (err) {
 251                         icsk->icsk_ext_hdr_len = exthdrlen;
 252                         icsk->icsk_af_ops = &ipv6_specific;
 253                         if (sk_is_mptcp(sk))
 254                                 mptcpv6_handle_mapped(sk, false);
 255                         sk->sk_backlog_rcv = tcp_v6_do_rcv;
 256 #ifdef CONFIG_TCP_MD5SIG
 257                         tp->af_specific = &tcp_sock_ipv6_specific;
 258 #endif
 259                         goto failure;
 260                 }
 261                 np->saddr = sk->sk_v6_rcv_saddr;
 262
 263                 return err;
 264         }
 265
 266         if (!ipv6_addr_any(&sk->sk_v6_rcv_saddr))
 267                 saddr = &sk->sk_v6_rcv_saddr;
 268
 269         fl6.flowi6_proto = IPPROTO_TCP;
 270         fl6.daddr = sk->sk_v6_daddr;
 271         fl6.saddr = saddr ? *saddr : np->saddr;
 272         fl6.flowi6_oif = sk->sk_bound_dev_if;
 273         fl6.flowi6_mark = sk->sk_mark;
 274         fl6.fl6_dport = usin->sin6_port;
 275         fl6.fl6_sport = inet->inet_sport;
 276         fl6.flowi6_uid = sk->sk_uid;
 277
 278         opt = rcu_dereference_protected(np->opt, lockdep_sock_is_held(sk));
 279         final_p = fl6_update_dst(&fl6, opt, &final);
 280
 281         security_sk_classify_flow(sk, flowi6_to_flowi_common(&fl6));
 282
 283         dst = ip6_dst_lookup_flow(sock_net(sk), sk, &fl6, final_p);
 284         if (IS_ERR(dst)) {
 285                 err = PTR_ERR(dst);
 286                 goto failure;
 287         }
 288
 289         if (!saddr) {
 290                 saddr = &fl6.saddr;
 291                 sk->sk_v6_rcv_saddr = *saddr;
 292         }
 293
 294         /* set the source address */
 295         np->saddr = *saddr;
 296         inet->inet_rcv_saddr = LOOPBACK4_IPV6;
 297
 298         sk->sk_gso_type = SKB_GSO_TCPV6;
 299         ip6_dst_store(sk, dst, NULL, NULL);
 300
 301         icsk->icsk_ext_hdr_len = 0;
 302         if (opt)
 303                 icsk->icsk_ext_hdr_len = opt->opt_flen +
 304                                          opt->opt_nflen;
 305
 306         tp->rx_opt.mss_clamp = IPV6_MIN_MTU - sizeof(struct tcphdr) - sizeof(struct ipv6hdr);
 307
 308         inet->inet_dport = usin->sin6_port;
 309
 310         tcp_set_state(sk, TCP_SYN_SENT);
 311         err = inet6_hash_connect(tcp_death_row, sk);
 312         if (err)
 313                 goto late_failure;
 314
 315         sk_set_txhash(sk);
 316
 317         if (likely(!tp->repair)) {
 318                 if (!tp->write_seq)
 319                         WRITE_ONCE(tp->write_seq,
 320                                    secure_tcpv6_seq(np->saddr.s6_addr32,
 321                                                     sk->sk_v6_daddr.s6_addr32,
 322                                                     inet->inet_sport,
 323                                                     inet->inet_dport));
 324                 tp->tsoffset = secure_tcpv6_ts_off(sock_net(sk),
 325                                                    np->saddr.s6_addr32,
 326                                                    sk->sk_v6_daddr.s6_addr32);
 327         }
 328
 329         if (tcp_fastopen_defer_connect(sk, &err))
 330                 return err;
 331         if (err)
 332                 goto late_failure;
 333
 334         err = tcp_connect(sk);
 335         if (err)
 336                 goto late_failure;
 337
 338         return 0;
 339
 340 late_failure:
 341         tcp_set_state(sk, TCP_CLOSE);
 342 failure:
 343         inet->inet_dport = 0;
 344         sk->sk_route_caps = 0;
 345         return err;
 346 }
 347
 348 static void tcp_v6_mtu_reduced(struct sock *sk)
 349 {
 350         struct dst_entry *dst;
 351         u32 mtu;
 352
 353         if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE))
 354                 return;
 355
 356         mtu = READ_ONCE(tcp_sk(sk)->mtu_info);
 357
 358         /* Drop requests trying to increase our current mss.
 359          * Check done in __ip6_rt_update_pmtu() is too late.
 360          */
 361         if (tcp_mtu_to_mss(sk, mtu) >= tcp_sk(sk)->mss_cache)
 362                 return;
 363
 364         dst = inet6_csk_update_pmtu(sk, mtu);
 365         if (!dst)
 366                 return;
 367
 368         if (inet_csk(sk)->icsk_pmtu_cookie > dst_mtu(dst)) {
 369                 tcp_sync_mss(sk, dst_mtu(dst));
 370                 tcp_simple_retransmit(sk);
 371         }
 372 }
 373
 374 static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 375                 u8 type, u8 code, int offset, __be32 info)
 376 {
 377         const struct ipv6hdr *hdr = (const struct ipv6hdr *)skb->data;
 378         const struct tcphdr *th = (struct tcphdr *)(skb->data+offset);
 379         struct net *net = dev_net(skb->dev);
 380         struct request_sock *fastopen;
 381         struct ipv6_pinfo *np;
 382         struct tcp_sock *tp;
 383         __u32 seq, snd_una;
 384         struct sock *sk;
 385         bool fatal;
 386         int err;
 387
 388         sk = __inet6_lookup_established(net, &tcp_hashinfo,
 389                                         &hdr->daddr, th->dest,
 390                                         &hdr->saddr, ntohs(th->source),
 391                                         skb->dev->ifindex, inet6_sdif(skb));
 392
 393         if (!sk) {
 394                 __ICMP6_INC_STATS(net, __in6_dev_get(skb->dev),
 395                                   ICMP6_MIB_INERRORS);
 396                 return -ENOENT;
 397         }
 398
 399         if (sk->sk_state == TCP_TIME_WAIT) {
 400                 inet_twsk_put(inet_twsk(sk));
 401                 return 0;
 402         }
 403         seq = ntohl(th->seq);
 404         fatal = icmpv6_err_convert(type, code, &err);
 405         if (sk->sk_state == TCP_NEW_SYN_RECV) {
 406                 tcp_req_err(sk, seq, fatal);
 407                 return 0;
 408         }
 409
 410         bh_lock_sock(sk);
 411         if (sock_owned_by_user(sk) && type != ICMPV6_PKT_TOOBIG)
 412                 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
 413
 414         if (sk->sk_state == TCP_CLOSE)
 415                 goto out;
 416
 417         if (ipv6_hdr(skb)->hop_limit < tcp_inet6_sk(sk)->min_hopcount) {
 418                 __NET_INC_STATS(net, LINUX_MIB_TCPMINTTLDROP);
 419                 goto out;
 420         }
 421
 422         tp = tcp_sk(sk);
 423         /* XXX (TFO) - tp->snd_una should be ISN (tcp_create_openreq_child() */
 424         fastopen = rcu_dereference(tp->fastopen_rsk);
 425         snd_una = fastopen ? tcp_rsk(fastopen)->snt_isn : tp->snd_una;
 426         if (sk->sk_state != TCP_LISTEN &&
 427             !between(seq, snd_una, tp->snd_nxt)) {
 428                 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
 429                 goto out;
 430         }
 431
 432         np = tcp_inet6_sk(sk);
 433
 434         if (type == NDISC_REDIRECT) {
 435                 if (!sock_owned_by_user(sk)) {
 436                         struct dst_entry *dst = __sk_dst_check(sk, np->dst_cookie);
 437
 438                         if (dst)
 439                                 dst->ops->redirect(dst, sk, skb);
 440                 }
 441                 goto out;
 442         }
 443
 444         if (type == ICMPV6_PKT_TOOBIG) {
 445                 u32 mtu = ntohl(info);
 446
 447                 /* We are not interested in TCP_LISTEN and open_requests
 448                  * (SYN-ACKs send out by Linux are always <576bytes so
 449                  * they should go through unfragmented).
 450                  */
 451                 if (sk->sk_state == TCP_LISTEN)
 452                         goto out;
 453
 454                 if (!ip6_sk_accept_pmtu(sk))
 455                         goto out;
 456
 457                 if (mtu < IPV6_MIN_MTU)
 458                         goto out;
 459
 460                 WRITE_ONCE(tp->mtu_info, mtu);
 461
 462                 if (!sock_owned_by_user(sk))
 463                         tcp_v6_mtu_reduced(sk);
 464                 else if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED,
 465                                            &sk->sk_tsq_flags))
 466                         sock_hold(sk);
 467                 goto out;
 468         }
 469
 470
 471         /* Might be for an request_sock */
 472         switch (sk->sk_state) {
 473         case TCP_SYN_SENT:
 474         case TCP_SYN_RECV:
 475                 /* Only in fast or simultaneous open. If a fast open socket is
 476                  * already accepted it is treated as a connected one below.
 477                  */
 478                 if (fastopen && !fastopen->sk)
 479                         break;
 480
 481                 ipv6_icmp_error(sk, skb, err, th->dest, ntohl(info), (u8 *)th);
 482
 483                 if (!sock_owned_by_user(sk)) {
 484                         sk->sk_err = err;
 485                         sk_error_report(sk);            /* Wake people up to see the error (see connect in sock.c) */
 486
 487                         tcp_done(sk);
 488                 } else
 489                         sk->sk_err_soft = err;
 490                 goto out;
 491         case TCP_LISTEN:
 492                 break;
 493         default:
 494                 /* check if this ICMP message allows revert of backoff.
 495                  * (see RFC 6069)
 496                  */
 497                 if (!fastopen && type == ICMPV6_DEST_UNREACH &&
 498                     code == ICMPV6_NOROUTE)
 499                         tcp_ld_RTO_revert(sk, seq);
 500         }
 501
 502         if (!sock_owned_by_user(sk) && np->recverr) {
 503                 sk->sk_err = err;
 504                 sk_error_report(sk);
 505         } else
 506                 sk->sk_err_soft = err;
 507
 508 out:
 509         bh_unlock_sock(sk);
 510         sock_put(sk);
 511         return 0;
 512 }
 513
 514
 515 static int tcp_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
 516                               struct flowi *fl,
 517                               struct request_sock *req,
 518                               struct tcp_fastopen_cookie *foc,
 519                               enum tcp_synack_type synack_type,
 520                               struct sk_buff *syn_skb)
 521 {
 522         struct inet_request_sock *ireq = inet_rsk(req);
 523         struct ipv6_pinfo *np = tcp_inet6_sk(sk);
 524         struct ipv6_txoptions *opt;
 525         struct flowi6 *fl6 = &fl->u.ip6;
 526         struct sk_buff *skb;
 527         int err = -ENOMEM;
 528         u8 tclass;
 529
 530         /* First, grab a route. */
 531         if (!dst && (dst = inet6_csk_route_req(sk, fl6, req,
 532                                                IPPROTO_TCP)) == NULL)
 533                 goto done;
 534
 535         skb = tcp_make_synack(sk, dst, req, foc, synack_type, syn_skb);
 536
 537         if (skb) {
 538                 __tcp_v6_send_check(skb, &ireq->ir_v6_loc_addr,
 539                                     &ireq->ir_v6_rmt_addr);
 540
 541                 fl6->daddr = ireq->ir_v6_rmt_addr;
 542                 if (np->repflow && ireq->pktopts)
 543                         fl6->flowlabel = ip6_flowlabel(ipv6_hdr(ireq->pktopts));
 544
 545                 tclass = sock_net(sk)->ipv4.sysctl_tcp_reflect_tos ?
 546                                 (tcp_rsk(req)->syn_tos & ~INET_ECN_MASK) |
 547                                 (np->tclass & INET_ECN_MASK) :
 548                                 np->tclass;
 549
 550                 if (!INET_ECN_is_capable(tclass) &&
 551                     tcp_bpf_ca_needs_ecn((struct sock *)req))
 552                         tclass |= INET_ECN_ECT_0;
 553
 554                 rcu_read_lock();
 555                 opt = ireq->ipv6_opt;
 556                 if (!opt)
 557                         opt = rcu_dereference(np->opt);
 558                 err = ip6_xmit(sk, skb, fl6, skb->mark ? : sk->sk_mark, opt,
 559                                tclass, sk->sk_priority);
 560                 rcu_read_unlock();
 561                 err = net_xmit_eval(err);
 562         }
 563
 564 done:
 565         return err;
 566 }
 567
 568
 569 static void tcp_v6_reqsk_destructor(struct request_sock *req)
 570 {
 571         kfree(inet_rsk(req)->ipv6_opt);
 572         kfree_skb(inet_rsk(req)->pktopts);
 573 }
 574
 575 #ifdef CONFIG_TCP_MD5SIG
 576 static struct tcp_md5sig_key *tcp_v6_md5_do_lookup(const struct sock *sk,
 577                                                    const struct in6_addr *addr,
 578                                                    int l3index)
 579 {
 580         return tcp_md5_do_lookup(sk, l3index,
 581                                  (union tcp_md5_addr *)addr, AF_INET6);
 582 }
 583
 584 static struct tcp_md5sig_key *tcp_v6_md5_lookup(const struct sock *sk,
 585                                                 const struct sock *addr_sk)
 586 {
 587         int l3index;
 588
 589         l3index = l3mdev_master_ifindex_by_index(sock_net(sk),
 590                                                  addr_sk->sk_bound_dev_if);
 591         return tcp_v6_md5_do_lookup(sk, &addr_sk->sk_v6_daddr,
 592                                     l3index);
 593 }
 594
 595 static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
 596                                  sockptr_t optval, int optlen)
 597 {
 598         struct tcp_md5sig cmd;
 599         struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&cmd.tcpm_addr;
 600         int l3index = 0;
 601         u8 prefixlen;
 602         u8 flags;
 603
 604         if (optlen < sizeof(cmd))
 605                 return -EINVAL;
 606
 607         if (copy_from_sockptr(&cmd, optval, sizeof(cmd)))
 608                 return -EFAULT;
 609
 610         if (sin6->sin6_family != AF_INET6)
 611                 return -EINVAL;
 612
 613         flags = cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX;
 614
 615         if (optname == TCP_MD5SIG_EXT &&
 616             cmd.tcpm_flags & TCP_MD5SIG_FLAG_PREFIX) {
 617                 prefixlen = cmd.tcpm_prefixlen;
 618                 if (prefixlen > 128 || (ipv6_addr_v4mapped(&sin6->sin6_addr) &&
 619                                         prefixlen > 32))
 620                         return -EINVAL;
 621         } else {
 622                 prefixlen = ipv6_addr_v4mapped(&sin6->sin6_addr) ? 32 : 128;
 623         }
 624
 625         if (optname == TCP_MD5SIG_EXT && cmd.tcpm_ifindex &&
 626             cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX) {
 627                 struct net_device *dev;
 628
 629                 rcu_read_lock();
 630                 dev = dev_get_by_index_rcu(sock_net(sk), cmd.tcpm_ifindex);
 631                 if (dev && netif_is_l3_master(dev))
 632                         l3index = dev->ifindex;
 633                 rcu_read_unlock();
 634
 635                 /* ok to reference set/not set outside of rcu;
 636                  * right now device MUST be an L3 master
 637                  */
 638                 if (!dev || !l3index)
 639                         return -EINVAL;
 640         }
 641
 642         if (!cmd.tcpm_keylen) {
 643                 if (ipv6_addr_v4mapped(&sin6->sin6_addr))
 644                         return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin6->sin6_addr.s6_addr32[3],
 645                                               AF_INET, prefixlen,
 646                                               l3index, flags);
 647                 return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin6->sin6_addr,
 648                                       AF_INET6, prefixlen, l3index, flags);
 649         }
 650
 651         if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
 652                 return -EINVAL;
 653
 654         if (ipv6_addr_v4mapped(&sin6->sin6_addr))
 655                 return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin6->sin6_addr.s6_addr32[3],
 656                                       AF_INET, prefixlen, l3index, flags,
 657                                       cmd.tcpm_key, cmd.tcpm_keylen,
 658                                       GFP_KERNEL);
 659
 660         return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin6->sin6_addr,
 661                               AF_INET6, prefixlen, l3index, flags,
 662                               cmd.tcpm_key, cmd.tcpm_keylen, GFP_KERNEL);
 663 }
 664
 665 static int tcp_v6_md5_hash_headers(struct tcp_md5sig_pool *hp,
 666                                    const struct in6_addr *daddr,
 667                                    const struct in6_addr *saddr,
 668                                    const struct tcphdr *th, int nbytes)
 669 {
 670         struct tcp6_pseudohdr *bp;
 671         struct scatterlist sg;
 672         struct tcphdr *_th;
 673
 674         bp = hp->scratch;
 675         /* 1. TCP pseudo-header (RFC2460) */
 676         bp->saddr = *saddr;
 677         bp->daddr = *daddr;
 678         bp->protocol = cpu_to_be32(IPPROTO_TCP);
 679         bp->len = cpu_to_be32(nbytes);
 680
 681         _th = (struct tcphdr *)(bp + 1);
 682         memcpy(_th, th, sizeof(*th));
 683         _th->check = 0;
 684
 685         sg_init_one(&sg, bp, sizeof(*bp) + sizeof(*th));
 686         ahash_request_set_crypt(hp->md5_req, &sg, NULL,
 687                                 sizeof(*bp) + sizeof(*th));
 688         return crypto_ahash_update(hp->md5_req);
 689 }
 690
 691 static int tcp_v6_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key,
 692                                const struct in6_addr *daddr, struct in6_addr *saddr,
 693                                const struct tcphdr *th)
 694 {
 695         struct tcp_md5sig_pool *hp;
 696         struct ahash_request *req;
 697
 698         hp = tcp_get_md5sig_pool();
 699         if (!hp)
 700                 goto clear_hash_noput;
 701         req = hp->md5_req;
 702
 703         if (crypto_ahash_init(req))
 704                 goto clear_hash;
 705         if (tcp_v6_md5_hash_headers(hp, daddr, saddr, th, th->doff << 2))
 706                 goto clear_hash;
 707         if (tcp_md5_hash_key(hp, key))
 708                 goto clear_hash;
 709         ahash_request_set_crypt(req, NULL, md5_hash, 0);
 710         if (crypto_ahash_final(req))
 711                 goto clear_hash;
 712
 713         tcp_put_md5sig_pool();
 714         return 0;
 715
 716 clear_hash:
 717         tcp_put_md5sig_pool();
 718 clear_hash_noput:
 719         memset(md5_hash, 0, 16);
 720         return 1;
 721 }
 722
 723 static int tcp_v6_md5_hash_skb(char *md5_hash,
 724                                const struct tcp_md5sig_key *key,
 725                                const struct sock *sk,
 726                                const struct sk_buff *skb)
 727 {
 728         const struct in6_addr *saddr, *daddr;
 729         struct tcp_md5sig_pool *hp;
 730         struct ahash_request *req;
 731         const struct tcphdr *th = tcp_hdr(skb);
 732
 733         if (sk) { /* valid for establish/request sockets */
 734                 saddr = &sk->sk_v6_rcv_saddr;
 735                 daddr = &sk->sk_v6_daddr;
 736         } else {
 737                 const struct ipv6hdr *ip6h = ipv6_hdr(skb);
 738                 saddr = &ip6h->saddr;
 739                 daddr = &ip6h->daddr;
 740         }
 741
 742         hp = tcp_get_md5sig_pool();
 743         if (!hp)
 744                 goto clear_hash_noput;
 745         req = hp->md5_req;
 746
 747         if (crypto_ahash_init(req))
 748                 goto clear_hash;
 749
 750         if (tcp_v6_md5_hash_headers(hp, daddr, saddr, th, skb->len))
 751                 goto clear_hash;
 752         if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2))
 753                 goto clear_hash;
 754         if (tcp_md5_hash_key(hp, key))
 755                 goto clear_hash;
 756         ahash_request_set_crypt(req, NULL, md5_hash, 0);
 757         if (crypto_ahash_final(req))
 758                 goto clear_hash;
 759
 760         tcp_put_md5sig_pool();
 761         return 0;
 762
 763 clear_hash:
 764         tcp_put_md5sig_pool();
 765 clear_hash_noput:
 766         memset(md5_hash, 0, 16);
 767         return 1;
 768 }
 769
 770 #endif
 771
 772 static bool tcp_v6_inbound_md5_hash(const struct sock *sk,
 773                                     const struct sk_buff *skb,
 774                                     int dif, int sdif)
 775 {
 776 #ifdef CONFIG_TCP_MD5SIG
 777         const __u8 *hash_location = NULL;
 778         struct tcp_md5sig_key *hash_expected;
 779         const struct ipv6hdr *ip6h = ipv6_hdr(skb);
 780         const struct tcphdr *th = tcp_hdr(skb);
 781         int genhash, l3index;
 782         u8 newhash[16];
 783
 784         /* sdif set, means packet ingressed via a device
 785          * in an L3 domain and dif is set to the l3mdev
 786          */
 787         l3index = sdif ? dif : 0;
 788
 789         hash_expected = tcp_v6_md5_do_lookup(sk, &ip6h->saddr, l3index);
 790         hash_location = tcp_parse_md5sig_option(th);
 791
 792         /* We've parsed the options - do we have a hash? */
 793         if (!hash_expected && !hash_location)
 794                 return false;
 795
 796         if (hash_expected && !hash_location) {
 797                 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
 798                 return true;
 799         }
 800
 801         if (!hash_expected && hash_location) {
 802                 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
 803                 return true;
 804         }
 805
 806         /* check the signature */
 807         genhash = tcp_v6_md5_hash_skb(newhash,
 808                                       hash_expected,
 809                                       NULL, skb);
 810
 811         if (genhash || memcmp(hash_location, newhash, 16) != 0) {
 812                 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5FAILURE);
 813                 net_info_ratelimited("MD5 Hash %s for [%pI6c]:%u->[%pI6c]:%u L3 index %d\n",
 814                                      genhash ? "failed" : "mismatch",
 815                                      &ip6h->saddr, ntohs(th->source),
 816                                      &ip6h->daddr, ntohs(th->dest), l3index);
 817                 return true;
 818         }
 819 #endif
 820         return false;
 821 }
 822
 823 static void tcp_v6_init_req(struct request_sock *req,
 824                             const struct sock *sk_listener,
 825                             struct sk_buff *skb)
 826 {
 827         bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
 828         struct inet_request_sock *ireq = inet_rsk(req);
 829         const struct ipv6_pinfo *np = tcp_inet6_sk(sk_listener);
 830
 831         ireq->ir_v6_rmt_addr = ipv6_hdr(skb)->saddr;
 832         ireq->ir_v6_loc_addr = ipv6_hdr(skb)->daddr;
 833
 834         /* So that link locals have meaning */
 835         if ((!sk_listener->sk_bound_dev_if || l3_slave) &&
 836             ipv6_addr_type(&ireq->ir_v6_rmt_addr) & IPV6_ADDR_LINKLOCAL)
 837                 ireq->ir_iif = tcp_v6_iif(skb);
 838
 839         if (!TCP_SKB_CB(skb)->tcp_tw_isn &&
 840             (ipv6_opt_accepted(sk_listener, skb, &TCP_SKB_CB(skb)->header.h6) ||
 841              np->rxopt.bits.rxinfo ||
 842              np->rxopt.bits.rxoinfo || np->rxopt.bits.rxhlim ||
 843              np->rxopt.bits.rxohlim || np->repflow)) {
 844                 refcount_inc(&skb->users);
 845                 ireq->pktopts = skb;
 846         }
 847 }
 848
 849 static struct dst_entry *tcp_v6_route_req(const struct sock *sk,
 850                                           struct sk_buff *skb,
 851                                           struct flowi *fl,
 852                                           struct request_sock *req)
 853 {
 854         tcp_v6_init_req(req, sk, skb);
 855
 856         if (security_inet_conn_request(sk, skb, req))
 857                 return NULL;
 858
 859         return inet6_csk_route_req(sk, &fl->u.ip6, req, IPPROTO_TCP);
 860 }
 861
 862 struct request_sock_ops tcp6_request_sock_ops __read_mostly = {
 863         .family         =       AF_INET6,
 864         .obj_size       =       sizeof(struct tcp6_request_sock),
 865         .rtx_syn_ack    =       tcp_rtx_synack,
 866         .send_ack       =       tcp_v6_reqsk_send_ack,
 867         .destructor     =       tcp_v6_reqsk_destructor,
 868         .send_reset     =       tcp_v6_send_reset,
 869         .syn_ack_timeout =      tcp_syn_ack_timeout,
 870 };
 871
 872 const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {
 873         .mss_clamp      =       IPV6_MIN_MTU - sizeof(struct tcphdr) -
 874                                 sizeof(struct ipv6hdr),
 875 #ifdef CONFIG_TCP_MD5SIG
 876         .req_md5_lookup =       tcp_v6_md5_lookup,
 877         .calc_md5_hash  =       tcp_v6_md5_hash_skb,
 878 #endif
 879 #ifdef CONFIG_SYN_COOKIES
 880         .cookie_init_seq =      cookie_v6_init_sequence,
 881 #endif
 882         .route_req      =       tcp_v6_route_req,
 883         .init_seq       =       tcp_v6_init_seq,
 884         .init_ts_off    =       tcp_v6_init_ts_off,
 885         .send_synack    =       tcp_v6_send_synack,
 886 };
 887
 888 static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32 seq,
 889                                  u32 ack, u32 win, u32 tsval, u32 tsecr,
 890                                  int oif, struct tcp_md5sig_key *key, int rst,
 891                                  u8 tclass, __be32 label, u32 priority)
 892 {
 893         const struct tcphdr *th = tcp_hdr(skb);
 894         struct tcphdr *t1;
 895         struct sk_buff *buff;
 896         struct flowi6 fl6;
 897         struct net *net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
 898         struct sock *ctl_sk = net->ipv6.tcp_sk;
 899         unsigned int tot_len = sizeof(struct tcphdr);
 900         __be32 mrst = 0, *topt;
 901         struct dst_entry *dst;
 902         __u32 mark = 0;
 903
 904         if (tsecr)
 905                 tot_len += TCPOLEN_TSTAMP_ALIGNED;
 906 #ifdef CONFIG_TCP_MD5SIG
 907         if (key)
 908                 tot_len += TCPOLEN_MD5SIG_ALIGNED;
 909 #endif
 910
 911 #ifdef CONFIG_MPTCP
 912         if (rst && !key) {
 913                 mrst = mptcp_reset_option(skb);
 914
 915                 if (mrst)
 916                         tot_len += sizeof(__be32);
 917         }
 918 #endif
 919
 920         buff = alloc_skb(MAX_HEADER + sizeof(struct ipv6hdr) + tot_len,
 921                          GFP_ATOMIC);
 922         if (!buff)
 923                 return;
 924
 925         skb_reserve(buff, MAX_HEADER + sizeof(struct ipv6hdr) + tot_len);
 926
 927         t1 = skb_push(buff, tot_len);
 928         skb_reset_transport_header(buff);
 929
 930         /* Swap the send and the receive. */
 931         memset(t1, 0, sizeof(*t1));
 932         t1->dest = th->source;
 933         t1->source = th->dest;
 934         t1->doff = tot_len / 4;
 935         t1->seq = htonl(seq);
 936         t1->ack_seq = htonl(ack);
 937         t1->ack = !rst || !th->ack;
 938         t1->rst = rst;
 939         t1->window = htons(win);
 940
 941         topt = (__be32 *)(t1 + 1);
 942
 943         if (tsecr) {
 944                 *topt++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
 945                                 (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP);
 946                 *topt++ = htonl(tsval);
 947                 *topt++ = htonl(tsecr);
 948         }
 949
 950         if (mrst)
 951                 *topt++ = mrst;
 952
 953 #ifdef CONFIG_TCP_MD5SIG
 954         if (key) {
 955                 *topt++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
 956                                 (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG);
 957                 tcp_v6_md5_hash_hdr((__u8 *)topt, key,
 958                                     &ipv6_hdr(skb)->saddr,
 959                                     &ipv6_hdr(skb)->daddr, t1);
 960         }
 961 #endif
 962
 963         memset(&fl6, 0, sizeof(fl6));
 964         fl6.daddr = ipv6_hdr(skb)->saddr;
 965         fl6.saddr = ipv6_hdr(skb)->daddr;
 966         fl6.flowlabel = label;
 967
 968         buff->ip_summed = CHECKSUM_PARTIAL;
 969         buff->csum = 0;
 970
 971         __tcp_v6_send_check(buff, &fl6.saddr, &fl6.daddr);
 972
 973         fl6.flowi6_proto = IPPROTO_TCP;
 974         if (rt6_need_strict(&fl6.daddr) && !oif)
 975                 fl6.flowi6_oif = tcp_v6_iif(skb);
 976         else {
 977                 if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
 978                         oif = skb->skb_iif;
 979
 980                 fl6.flowi6_oif = oif;
 981         }
 982
 983         if (sk) {
 984                 if (sk->sk_state == TCP_TIME_WAIT) {
 985                         mark = inet_twsk(sk)->tw_mark;
 986                         /* autoflowlabel relies on buff->hash */
 987                         skb_set_hash(buff, inet_twsk(sk)->tw_txhash,
 988                                      PKT_HASH_TYPE_L4);
 989                 } else {
 990                         mark = sk->sk_mark;
 991                 }
 992                 buff->tstamp = tcp_transmit_time(sk);
 993         }
 994         fl6.flowi6_mark = IP6_REPLY_MARK(net, skb->mark) ?: mark;
 995         fl6.fl6_dport = t1->dest;
 996         fl6.fl6_sport = t1->source;
 997         fl6.flowi6_uid = sock_net_uid(net, sk && sk_fullsock(sk) ? sk : NULL);
 998         security_skb_classify_flow(skb, flowi6_to_flowi_common(&fl6));
 999
1000         /* Pass a socket to ip6_dst_lookup either it is for RST
1001          * Underlying function will use this to retrieve the network
1002          * namespace
1003          */
1004         dst = ip6_dst_lookup_flow(sock_net(ctl_sk), ctl_sk, &fl6, NULL);
1005         if (!IS_ERR(dst)) {
1006                 skb_dst_set(buff, dst);
1007                 ip6_xmit(ctl_sk, buff, &fl6, fl6.flowi6_mark, NULL,
1008                          tclass & ~INET_ECN_MASK, priority);
1009                 TCP_INC_STATS(net, TCP_MIB_OUTSEGS);
1010                 if (rst)
1011                         TCP_INC_STATS(net, TCP_MIB_OUTRSTS);
1012                 return;
1013         }
1014
1015         kfree_skb(buff);
1016 }
1017
1018 static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
1019 {
1020         const struct tcphdr *th = tcp_hdr(skb);
1021         struct ipv6hdr *ipv6h = ipv6_hdr(skb);
1022         u32 seq = 0, ack_seq = 0;
1023         struct tcp_md5sig_key *key = NULL;
1024 #ifdef CONFIG_TCP_MD5SIG
1025         const __u8 *hash_location = NULL;
1026         unsigned char newhash[16];
1027         int genhash;
1028         struct sock *sk1 = NULL;
1029 #endif
1030         __be32 label = 0;
1031         u32 priority = 0;
1032         struct net *net;
1033         int oif = 0;
1034
1035         if (th->rst)
1036                 return;
1037
1038         /* If sk not NULL, it means we did a successful lookup and incoming
1039          * route had to be correct. prequeue might have dropped our dst.
1040          */
1041         if (!sk && !ipv6_unicast_destination(skb))
1042                 return;
1043
1044         net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
1045 #ifdef CONFIG_TCP_MD5SIG
1046         rcu_read_lock();
1047         hash_location = tcp_parse_md5sig_option(th);
1048         if (sk && sk_fullsock(sk)) {
1049                 int l3index;
1050
1051                 /* sdif set, means packet ingressed via a device
1052                  * in an L3 domain and inet_iif is set to it.
1053                  */
1054                 l3index = tcp_v6_sdif(skb) ? tcp_v6_iif_l3_slave(skb) : 0;
1055                 key = tcp_v6_md5_do_lookup(sk, &ipv6h->saddr, l3index);
1056         } else if (hash_location) {
1057                 int dif = tcp_v6_iif_l3_slave(skb);
1058                 int sdif = tcp_v6_sdif(skb);
1059                 int l3index;
1060
1061                 /*
1062                  * active side is lost. Try to find listening socket through
1063                  * source port, and then find md5 key through listening socket.
1064                  * we are not loose security here:
1065                  * Incoming packet is checked with md5 hash with finding key,
1066                  * no RST generated if md5 hash doesn't match.
1067                  */
1068                 sk1 = inet6_lookup_listener(net,
1069                                            &tcp_hashinfo, NULL, 0,
1070                                            &ipv6h->saddr,
1071                                            th->source, &ipv6h->daddr,
1072                                            ntohs(th->source), dif, sdif);
1073                 if (!sk1)
1074                         goto out;
1075
1076                 /* sdif set, means packet ingressed via a device
1077                  * in an L3 domain and dif is set to it.
1078                  */
1079                 l3index = tcp_v6_sdif(skb) ? dif : 0;
1080
1081                 key = tcp_v6_md5_do_lookup(sk1, &ipv6h->saddr, l3index);
1082                 if (!key)
1083                         goto out;
1084
1085                 genhash = tcp_v6_md5_hash_skb(newhash, key, NULL, skb);
1086                 if (genhash || memcmp(hash_location, newhash, 16) != 0)
1087                         goto out;
1088         }
1089 #endif
1090
1091         if (th->ack)
1092                 seq = ntohl(th->ack_seq);
1093         else
1094                 ack_seq = ntohl(th->seq) + th->syn + th->fin + skb->len -
1095                           (th->doff << 2);
1096
1097         if (sk) {
1098                 oif = sk->sk_bound_dev_if;
1099                 if (sk_fullsock(sk)) {
1100                         const struct ipv6_pinfo *np = tcp_inet6_sk(sk);
1101
1102                         trace_tcp_send_reset(sk, skb);
1103                         if (np->repflow)
1104                                 label = ip6_flowlabel(ipv6h);
1105                         priority = sk->sk_priority;
1106                 }
1107                 if (sk->sk_state == TCP_TIME_WAIT) {
1108                         label = cpu_to_be32(inet_twsk(sk)->tw_flowlabel);
1109                         priority = inet_twsk(sk)->tw_priority;
1110                 }
1111         } else {
1112                 if (net->ipv6.sysctl.flowlabel_reflect & FLOWLABEL_REFLECT_TCP_RESET)
1113                         label = ip6_flowlabel(ipv6h);
1114         }
1115
1116         tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, key, 1,
1117                              ipv6_get_dsfield(ipv6h), label, priority);
1118
1119 #ifdef CONFIG_TCP_MD5SIG
1120 out:
1121         rcu_read_unlock();
1122 #endif
1123 }
1124
1125 static void tcp_v6_send_ack(const struct sock *sk, struct sk_buff *skb, u32 seq,
1126                             u32 ack, u32 win, u32 tsval, u32 tsecr, int oif,
1127                             struct tcp_md5sig_key *key, u8 tclass,
1128                             __be32 label, u32 priority)
1129 {
1130         tcp_v6_send_response(sk, skb, seq, ack, win, tsval, tsecr, oif, key, 0,
1131                              tclass, label, priority);
1132 }
1133
1134 static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
1135 {
1136         struct inet_timewait_sock *tw = inet_twsk(sk);
1137         struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
1138
1139         tcp_v6_send_ack(sk, skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
1140                         tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
1141                         tcp_time_stamp_raw() + tcptw->tw_ts_offset,
1142                         tcptw->tw_ts_recent, tw->tw_bound_dev_if, tcp_twsk_md5_key(tcptw),
1143                         tw->tw_tclass, cpu_to_be32(tw->tw_flowlabel), tw->tw_priority);
1144
1145         inet_twsk_put(tw);
1146 }
1147
1148 static void tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
1149                                   struct request_sock *req)
1150 {
1151         int l3index;
1152
1153         l3index = tcp_v6_sdif(skb) ? tcp_v6_iif_l3_slave(skb) : 0;
1154
1155         /* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV
1156          * sk->sk_state == TCP_SYN_RECV -> for Fast Open.
1157          */
1158         /* RFC 7323 2.3
1159          * The window field (SEG.WND) of every outgoing segment, with the
1160          * exception of <SYN> segments, MUST be right-shifted by
1161          * Rcv.Wind.Shift bits:
1162          */
1163         tcp_v6_send_ack(sk, skb, (sk->sk_state == TCP_LISTEN) ?
1164                         tcp_rsk(req)->snt_isn + 1 : tcp_sk(sk)->snd_nxt,
1165                         tcp_rsk(req)->rcv_nxt,
1166                         req->rsk_rcv_wnd >> inet_rsk(req)->rcv_wscale,
1167                         tcp_time_stamp_raw() + tcp_rsk(req)->ts_off,
1168                         req->ts_recent, sk->sk_bound_dev_if,
1169                         tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->saddr, l3index),
1170                         ipv6_get_dsfield(ipv6_hdr(skb)), 0, sk->sk_priority);
1171 }
1172
1173
1174 static struct sock *tcp_v6_cookie_check(struct sock *sk, struct sk_buff *skb)
1175 {
1176 #ifdef CONFIG_SYN_COOKIES
1177         const struct tcphdr *th = tcp_hdr(skb);
1178
1179         if (!th->syn)
1180                 sk = cookie_v6_check(sk, skb);
1181 #endif
1182         return sk;
1183 }
1184
1185 u16 tcp_v6_get_syncookie(struct sock *sk, struct ipv6hdr *iph,
1186                          struct tcphdr *th, u32 *cookie)
1187 {
1188         u16 mss = 0;
1189 #ifdef CONFIG_SYN_COOKIES
1190         mss = tcp_get_syncookie_mss(&tcp6_request_sock_ops,
1191                                     &tcp_request_sock_ipv6_ops, sk, th);
1192         if (mss) {
1193                 *cookie = __cookie_v6_init_sequence(iph, th, &mss);
1194                 tcp_synq_overflow(sk);
1195         }
1196 #endif
1197         return mss;
1198 }
1199
1200 static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
1201 {
1202         if (skb->protocol == htons(ETH_P_IP))
1203                 return tcp_v4_conn_request(sk, skb);
1204
1205         if (!ipv6_unicast_destination(skb))
1206                 goto drop;
1207
1208         if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) {
1209                 __IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
1210                 return 0;
1211         }
1212
1213         return tcp_conn_request(&tcp6_request_sock_ops,
1214                                 &tcp_request_sock_ipv6_ops, sk, skb);
1215
1216 drop:
1217         tcp_listendrop(sk);
1218         return 0; /* don't send reset */
1219 }
1220
1221 static void tcp_v6_restore_cb(struct sk_buff *skb)
1222 {
1223         /* We need to move header back to the beginning if xfrm6_policy_check()
1224          * and tcp_v6_fill_cb() are going to be called again.
1225          * ip6_datagram_recv_specific_ctl() also expects IP6CB to be there.
1226          */
1227         memmove(IP6CB(skb), &TCP_SKB_CB(skb)->header.h6,
1228                 sizeof(struct inet6_skb_parm));
1229 }
1230
1231 static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
1232                                          struct request_sock *req,
1233                                          struct dst_entry *dst,
1234                                          struct request_sock *req_unhash,
1235                                          bool *own_req)
1236 {
1237         struct inet_request_sock *ireq;
1238         struct ipv6_pinfo *newnp;
1239         const struct ipv6_pinfo *np = tcp_inet6_sk(sk);
1240         struct ipv6_txoptions *opt;
1241         struct inet_sock *newinet;
1242         bool found_dup_sk = false;
1243         struct tcp_sock *newtp;
1244         struct sock *newsk;
1245 #ifdef CONFIG_TCP_MD5SIG
1246         struct tcp_md5sig_key *key;
1247         int l3index;
1248 #endif
1249         struct flowi6 fl6;
1250
1251         if (skb->protocol == htons(ETH_P_IP)) {
1252                 /*
1253                  *      v6 mapped
1254                  */
1255
1256                 newsk = tcp_v4_syn_recv_sock(sk, skb, req, dst,
1257                                              req_unhash, own_req);
1258
1259                 if (!newsk)
1260                         return NULL;
1261
1262                 inet_sk(newsk)->pinet6 = tcp_inet6_sk(newsk);
1263
1264                 newinet = inet_sk(newsk);
1265                 newnp = tcp_inet6_sk(newsk);
1266                 newtp = tcp_sk(newsk);
1267
1268                 memcpy(newnp, np, sizeof(struct ipv6_pinfo));
1269
1270                 newnp->saddr = newsk->sk_v6_rcv_saddr;
1271
1272                 inet_csk(newsk)->icsk_af_ops = &ipv6_mapped;
1273                 if (sk_is_mptcp(newsk))
1274                         mptcpv6_handle_mapped(newsk, true);
1275                 newsk->sk_backlog_rcv = tcp_v4_do_rcv;
1276 #ifdef CONFIG_TCP_MD5SIG
1277                 newtp->af_specific = &tcp_sock_ipv6_mapped_specific;
1278 #endif
1279
1280                 newnp->ipv6_mc_list = NULL;
1281                 newnp->ipv6_ac_list = NULL;
1282                 newnp->ipv6_fl_list = NULL;
1283                 newnp->pktoptions  = NULL;
1284                 newnp->opt         = NULL;
1285                 newnp->mcast_oif   = inet_iif(skb);
1286                 newnp->mcast_hops  = ip_hdr(skb)->ttl;
1287                 newnp->rcv_flowinfo = 0;
1288                 if (np->repflow)
1289                         newnp->flow_label = 0;
1290
1291                 /*
1292                  * No need to charge this sock to the relevant IPv6 refcnt debug socks count
1293                  * here, tcp_create_openreq_child now does this for us, see the comment in
1294                  * that function for the gory details. -acme
1295                  */
1296
1297                 /* It is tricky place. Until this moment IPv4 tcp
1298                    worked with IPv6 icsk.icsk_af_ops.
1299                    Sync it now.
1300                  */
1301                 tcp_sync_mss(newsk, inet_csk(newsk)->icsk_pmtu_cookie);
1302
1303                 return newsk;
1304         }
1305
1306         ireq = inet_rsk(req);
1307
1308         if (sk_acceptq_is_full(sk))
1309                 goto out_overflow;
1310
1311         if (!dst) {
1312                 dst = inet6_csk_route_req(sk, &fl6, req, IPPROTO_TCP);
1313                 if (!dst)
1314                         goto out;
1315         }
1316
1317         newsk = tcp_create_openreq_child(sk, req, skb);
1318         if (!newsk)
1319                 goto out_nonewsk;
1320
1321         /*
1322          * No need to charge this sock to the relevant IPv6 refcnt debug socks
1323          * count here, tcp_create_openreq_child now does this for us, see the
1324          * comment in that function for the gory details. -acme
1325          */
1326
1327         newsk->sk_gso_type = SKB_GSO_TCPV6;
1328         ip6_dst_store(newsk, dst, NULL, NULL);
1329         inet6_sk_rx_dst_set(newsk, skb);
1330
1331         inet_sk(newsk)->pinet6 = tcp_inet6_sk(newsk);
1332
1333         newtp = tcp_sk(newsk);
1334         newinet = inet_sk(newsk);
1335         newnp = tcp_inet6_sk(newsk);
1336
1337         memcpy(newnp, np, sizeof(struct ipv6_pinfo));
1338
1339         newsk->sk_v6_daddr = ireq->ir_v6_rmt_addr;
1340         newnp->saddr = ireq->ir_v6_loc_addr;
1341         newsk->sk_v6_rcv_saddr = ireq->ir_v6_loc_addr;
1342         newsk->sk_bound_dev_if = ireq->ir_iif;
1343
1344         /* Now IPv6 options...
1345
1346            First: no IPv4 options.
1347          */
1348         newinet->inet_opt = NULL;
1349         newnp->ipv6_mc_list = NULL;
1350         newnp->ipv6_ac_list = NULL;
1351         newnp->ipv6_fl_list = NULL;
1352
1353         /* Clone RX bits */
1354         newnp->rxopt.all = np->rxopt.all;
1355
1356         newnp->pktoptions = NULL;
1357         newnp->opt        = NULL;
1358         newnp->mcast_oif  = tcp_v6_iif(skb);
1359         newnp->mcast_hops = ipv6_hdr(skb)->hop_limit;
1360         newnp->rcv_flowinfo = ip6_flowinfo(ipv6_hdr(skb));
1361         if (np->repflow)
1362                 newnp->flow_label = ip6_flowlabel(ipv6_hdr(skb));
1363
1364         /* Set ToS of the new socket based upon the value of incoming SYN.
1365          * ECT bits are set later in tcp_init_transfer().
1366          */
1367         if (sock_net(sk)->ipv4.sysctl_tcp_reflect_tos)
1368                 newnp->tclass = tcp_rsk(req)->syn_tos & ~INET_ECN_MASK;
1369
1370         /* Clone native IPv6 options from listening socket (if any)
1371
1372            Yes, keeping reference count would be much more clever,
1373            but we make one more one thing there: reattach optmem
1374            to newsk.
1375          */
1376         opt = ireq->ipv6_opt;
1377         if (!opt)
1378                 opt = rcu_dereference(np->opt);
1379         if (opt) {
1380                 opt = ipv6_dup_options(newsk, opt);
1381                 RCU_INIT_POINTER(newnp->opt, opt);
1382         }
1383         inet_csk(newsk)->icsk_ext_hdr_len = 0;
1384         if (opt)
1385                 inet_csk(newsk)->icsk_ext_hdr_len = opt->opt_nflen +
1386                                                     opt->opt_flen;
1387
1388         tcp_ca_openreq_child(newsk, dst);
1389
1390         tcp_sync_mss(newsk, dst_mtu(dst));
1391         newtp->advmss = tcp_mss_clamp(tcp_sk(sk), dst_metric_advmss(dst));
1392
1393         tcp_initialize_rcv_mss(newsk);
1394
1395         newinet->inet_daddr = newinet->inet_saddr = LOOPBACK4_IPV6;
1396         newinet->inet_rcv_saddr = LOOPBACK4_IPV6;
1397
1398 #ifdef CONFIG_TCP_MD5SIG
1399         l3index = l3mdev_master_ifindex_by_index(sock_net(sk), ireq->ir_iif);
1400
1401         /* Copy over the MD5 key from the original socket */
1402         key = tcp_v6_md5_do_lookup(sk, &newsk->sk_v6_daddr, l3index);
1403         if (key) {
1404                 /* We're using one, so create a matching key
1405                  * on the newsk structure. If we fail to get
1406                  * memory, then we end up not copying the key
1407                  * across. Shucks.
1408                  */
1409                 tcp_md5_do_add(newsk, (union tcp_md5_addr *)&newsk->sk_v6_daddr,
1410                                AF_INET6, 128, l3index, key->flags, key->key, key->keylen,
1411                                sk_gfp_mask(sk, GFP_ATOMIC));
1412         }
1413 #endif
1414
1415         if (__inet_inherit_port(sk, newsk) < 0) {
1416                 inet_csk_prepare_forced_close(newsk);
1417                 tcp_done(newsk);
1418                 goto out;
1419         }
1420         *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash),
1421                                        &found_dup_sk);
1422         if (*own_req) {
1423                 tcp_move_syn(newtp, req);
1424
1425                 /* Clone pktoptions received with SYN, if we own the req */
1426                 if (ireq->pktopts) {
1427                         newnp->pktoptions = skb_clone(ireq->pktopts,
1428                                                       sk_gfp_mask(sk, GFP_ATOMIC));
1429                         consume_skb(ireq->pktopts);
1430                         ireq->pktopts = NULL;
1431                         if (newnp->pktoptions) {
1432                                 tcp_v6_restore_cb(newnp->pktoptions);
1433                                 skb_set_owner_r(newnp->pktoptions, newsk);
1434                         }
1435                 }
1436         } else {
1437                 if (!req_unhash && found_dup_sk) {
1438                         /* This code path should only be executed in the
1439                          * syncookie case only
1440                          */
1441                         bh_unlock_sock(newsk);
1442                         sock_put(newsk);
1443                         newsk = NULL;
1444                 }
1445         }
1446
1447         return newsk;
1448
1449 out_overflow:
1450         __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
1451 out_nonewsk:
1452         dst_release(dst);
1453 out:
1454         tcp_listendrop(sk);
1455         return NULL;
1456 }
1457
1458 INDIRECT_CALLABLE_DECLARE(struct dst_entry *ipv4_dst_check(struct dst_entry *,
1459                                                            u32));
1460 /* The socket must have it's spinlock held when we get
1461  * here, unless it is a TCP_LISTEN socket.
1462  *
1463  * We have a potential double-lock case here, so even when
1464  * doing backlog processing we use the BH locking scheme.
1465  * This is because we cannot sleep with the original spinlock
1466  * held.
1467  */
1468 static int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
1469 {
1470         struct ipv6_pinfo *np = tcp_inet6_sk(sk);
1471         struct sk_buff *opt_skb = NULL;
1472         struct tcp_sock *tp;
1473
1474         /* Imagine: socket is IPv6. IPv4 packet arrives,
1475            goes to IPv4 receive handler and backlogged.
1476            From backlog it always goes here. Kerboom...
1477            Fortunately, tcp_rcv_established and rcv_established
1478            handle them correctly, but it is not case with
1479            tcp_v6_hnd_req and tcp_v6_send_reset().   --ANK
1480          */
1481
1482         if (skb->protocol == htons(ETH_P_IP))
1483                 return tcp_v4_do_rcv(sk, skb);
1484
1485         /*
1486          *      socket locking is here for SMP purposes as backlog rcv
1487          *      is currently called with bh processing disabled.
1488          */
1489
1490         /* Do Stevens' IPV6_PKTOPTIONS.
1491
1492            Yes, guys, it is the only place in our code, where we
1493            may make it not affecting IPv4.
1494            The rest of code is protocol independent,
1495            and I do not like idea to uglify IPv4.
1496
1497            Actually, all the idea behind IPV6_PKTOPTIONS
1498            looks not very well thought. For now we latch
1499            options, received in the last packet, enqueued
1500            by tcp. Feel free to propose better solution.
1501                                                --ANK (980728)
1502          */
1503         if (np->rxopt.all)
1504                 opt_skb = skb_clone(skb, sk_gfp_mask(sk, GFP_ATOMIC));
1505
1506         if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
1507                 struct dst_entry *dst = sk->sk_rx_dst;
1508
1509                 sock_rps_save_rxhash(sk, skb);
1510                 sk_mark_napi_id(sk, skb);
1511                 if (dst) {
1512                         if (inet_sk(sk)->rx_dst_ifindex != skb->skb_iif ||
1513                             INDIRECT_CALL_1(dst->ops->check, ip6_dst_check,
1514                                             dst, np->rx_dst_cookie) == NULL) {
1515                                 dst_release(dst);
1516                                 sk->sk_rx_dst = NULL;
1517                         }
1518                 }
1519
1520                 tcp_rcv_established(sk, skb);
1521                 if (opt_skb)
1522                         goto ipv6_pktoptions;
1523                 return 0;
1524         }
1525
1526         if (tcp_checksum_complete(skb))
1527                 goto csum_err;
1528
1529         if (sk->sk_state == TCP_LISTEN) {
1530                 struct sock *nsk = tcp_v6_cookie_check(sk, skb);
1531
1532                 if (!nsk)
1533                         goto discard;
1534
1535                 if (nsk != sk) {
1536                         if (tcp_child_process(sk, nsk, skb))
1537                                 goto reset;
1538                         if (opt_skb)
1539                                 __kfree_skb(opt_skb);
1540                         return 0;
1541                 }
1542         } else
1543                 sock_rps_save_rxhash(sk, skb);
1544
1545         if (tcp_rcv_state_process(sk, skb))
1546                 goto reset;
1547         if (opt_skb)
1548                 goto ipv6_pktoptions;
1549         return 0;
1550
1551 reset:
1552         tcp_v6_send_reset(sk, skb);
1553 discard:
1554         if (opt_skb)
1555                 __kfree_skb(opt_skb);
1556         kfree_skb(skb);
1557         return 0;
1558 csum_err:
1559         trace_tcp_bad_csum(skb);
1560         TCP_INC_STATS(sock_net(sk), TCP_MIB_CSUMERRORS);
1561         TCP_INC_STATS(sock_net(sk), TCP_MIB_INERRS);
1562         goto discard;
1563
1564
1565 ipv6_pktoptions:
1566         /* Do you ask, what is it?
1567
1568            1. skb was enqueued by tcp.
1569            2. skb is added to tail of read queue, rather than out of order.
1570            3. socket is not in passive state.
1571            4. Finally, it really contains options, which user wants to receive.
1572          */
1573         tp = tcp_sk(sk);
1574         if (TCP_SKB_CB(opt_skb)->end_seq == tp->rcv_nxt &&
1575             !((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))) {
1576                 if (np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo)
1577                         np->mcast_oif = tcp_v6_iif(opt_skb);
1578                 if (np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim)
1579                         np->mcast_hops = ipv6_hdr(opt_skb)->hop_limit;
1580                 if (np->rxopt.bits.rxflow || np->rxopt.bits.rxtclass)
1581                         np->rcv_flowinfo = ip6_flowinfo(ipv6_hdr(opt_skb));
1582                 if (np->repflow)
1583                         np->flow_label = ip6_flowlabel(ipv6_hdr(opt_skb));
1584                 if (ipv6_opt_accepted(sk, opt_skb, &TCP_SKB_CB(opt_skb)->header.h6)) {
1585                         skb_set_owner_r(opt_skb, sk);
1586                         tcp_v6_restore_cb(opt_skb);
1587                         opt_skb = xchg(&np->pktoptions, opt_skb);
1588                 } else {
1589                         __kfree_skb(opt_skb);
1590                         opt_skb = xchg(&np->pktoptions, NULL);
1591                 }
1592         }
1593
1594         kfree_skb(opt_skb);
1595         return 0;
1596 }
1597
1598 static void tcp_v6_fill_cb(struct sk_buff *skb, const struct ipv6hdr *hdr,
1599                            const struct tcphdr *th)
1600 {
1601         /* This is tricky: we move IP6CB at its correct location into
1602          * TCP_SKB_CB(). It must be done after xfrm6_policy_check(), because
1603          * _decode_session6() uses IP6CB().
1604          * barrier() makes sure compiler won't play aliasing games.
1605          */
1606         memmove(&TCP_SKB_CB(skb)->header.h6, IP6CB(skb),
1607                 sizeof(struct inet6_skb_parm));
1608         barrier();
1609
1610         TCP_SKB_CB(skb)->seq = ntohl(th->seq);
1611         TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
1612                                     skb->len - th->doff*4);
1613         TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
1614         TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th);
1615         TCP_SKB_CB(skb)->tcp_tw_isn = 0;
1616         TCP_SKB_CB(skb)->ip_dsfield = ipv6_get_dsfield(hdr);
1617         TCP_SKB_CB(skb)->sacked = 0;
1618         TCP_SKB_CB(skb)->has_rxtstamp =
1619                         skb->tstamp || skb_hwtstamps(skb)->hwtstamp;
1620 }
1621
1622 INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
1623 {
1624         struct sk_buff *skb_to_free;
1625         int sdif = inet6_sdif(skb);
1626         int dif = inet6_iif(skb);
1627         const struct tcphdr *th;
1628         const struct ipv6hdr *hdr;
1629         bool refcounted;
1630         struct sock *sk;
1631         int ret;
1632         struct net *net = dev_net(skb->dev);
1633
1634         if (skb->pkt_type != PACKET_HOST)
1635                 goto discard_it;
1636
1637         /*
1638          *      Count it even if it's bad.
1639          */
1640         __TCP_INC_STATS(net, TCP_MIB_INSEGS);
1641
1642         if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
1643                 goto discard_it;
1644
1645         th = (const struct tcphdr *)skb->data;
1646
1647         if (unlikely(th->doff < sizeof(struct tcphdr)/4))
1648                 goto bad_packet;
1649         if (!pskb_may_pull(skb, th->doff*4))
1650                 goto discard_it;
1651
1652         if (skb_checksum_init(skb, IPPROTO_TCP, ip6_compute_pseudo))
1653                 goto csum_error;
1654
1655         th = (const struct tcphdr *)skb->data;
1656         hdr = ipv6_hdr(skb);
1657
1658 lookup:
1659         sk = __inet6_lookup_skb(&tcp_hashinfo, skb, __tcp_hdrlen(th),
1660                                 th->source, th->dest, inet6_iif(skb), sdif,
1661                                 &refcounted);
1662         if (!sk)
1663                 goto no_tcp_socket;
1664
1665 process:
1666         if (sk->sk_state == TCP_TIME_WAIT)
1667                 goto do_time_wait;
1668
1669         if (sk->sk_state == TCP_NEW_SYN_RECV) {
1670                 struct request_sock *req = inet_reqsk(sk);
1671                 bool req_stolen = false;
1672                 struct sock *nsk;
1673
1674                 sk = req->rsk_listener;
1675                 if (tcp_v6_inbound_md5_hash(sk, skb, dif, sdif)) {
1676                         sk_drops_add(sk, skb);
1677                         reqsk_put(req);
1678                         goto discard_it;
1679                 }
1680                 if (tcp_checksum_complete(skb)) {
1681                         reqsk_put(req);
1682                         goto csum_error;
1683                 }
1684                 if (unlikely(sk->sk_state != TCP_LISTEN)) {
1685                         nsk = reuseport_migrate_sock(sk, req_to_sk(req), skb);
1686                         if (!nsk) {
1687                                 inet_csk_reqsk_queue_drop_and_put(sk, req);
1688                                 goto lookup;
1689                         }
1690                         sk = nsk;
1691                         /* reuseport_migrate_sock() has already held one sk_refcnt
1692                          * before returning.
1693                          */
1694                 } else {
1695                         sock_hold(sk);
1696                 }
1697                 refcounted = true;
1698                 nsk = NULL;
1699                 if (!tcp_filter(sk, skb)) {
1700                         th = (const struct tcphdr *)skb->data;
1701                         hdr = ipv6_hdr(skb);
1702                         tcp_v6_fill_cb(skb, hdr, th);
1703                         nsk = tcp_check_req(sk, skb, req, false, &req_stolen);
1704                 }
1705                 if (!nsk) {
1706                         reqsk_put(req);
1707                         if (req_stolen) {
1708                                 /* Another cpu got exclusive access to req
1709                                  * and created a full blown socket.
1710                                  * Try to feed this packet to this socket
1711                                  * instead of discarding it.
1712                                  */
1713                                 tcp_v6_restore_cb(skb);
1714                                 sock_put(sk);
1715                                 goto lookup;
1716                         }
1717                         goto discard_and_relse;
1718                 }
1719                 if (nsk == sk) {
1720                         reqsk_put(req);
1721                         tcp_v6_restore_cb(skb);
1722                 } else if (tcp_child_process(sk, nsk, skb)) {
1723                         tcp_v6_send_reset(nsk, skb);
1724                         goto discard_and_relse;
1725                 } else {
1726                         sock_put(sk);
1727                         return 0;
1728                 }
1729         }
1730         if (hdr->hop_limit < tcp_inet6_sk(sk)->min_hopcount) {
1731                 __NET_INC_STATS(net, LINUX_MIB_TCPMINTTLDROP);
1732                 goto discard_and_relse;
1733         }
1734
1735         if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
1736                 goto discard_and_relse;
1737
1738         if (tcp_v6_inbound_md5_hash(sk, skb, dif, sdif))
1739                 goto discard_and_relse;
1740
1741         if (tcp_filter(sk, skb))
1742                 goto discard_and_relse;
1743         th = (const struct tcphdr *)skb->data;
1744         hdr = ipv6_hdr(skb);
1745         tcp_v6_fill_cb(skb, hdr, th);
1746
1747         skb->dev = NULL;
1748
1749         if (sk->sk_state == TCP_LISTEN) {
1750                 ret = tcp_v6_do_rcv(sk, skb);
1751                 goto put_and_return;
1752         }
1753
1754         sk_incoming_cpu_update(sk);
1755
1756         bh_lock_sock_nested(sk);
1757         tcp_segs_in(tcp_sk(sk), skb);
1758         ret = 0;
1759         if (!sock_owned_by_user(sk)) {
1760                 skb_to_free = sk->sk_rx_skb_cache;
1761                 sk->sk_rx_skb_cache = NULL;
1762                 ret = tcp_v6_do_rcv(sk, skb);
1763         } else {
1764                 if (tcp_add_backlog(sk, skb))
1765                         goto discard_and_relse;
1766                 skb_to_free = NULL;
1767         }
1768         bh_unlock_sock(sk);
1769         if (skb_to_free)
1770                 __kfree_skb(skb_to_free);
1771 put_and_return:
1772         if (refcounted)
1773                 sock_put(sk);
1774         return ret ? -1 : 0;
1775
1776 no_tcp_socket:
1777         if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
1778                 goto discard_it;
1779
1780         tcp_v6_fill_cb(skb, hdr, th);
1781
1782         if (tcp_checksum_complete(skb)) {
1783 csum_error:
1784                 trace_tcp_bad_csum(skb);
1785                 __TCP_INC_STATS(net, TCP_MIB_CSUMERRORS);
1786 bad_packet:
1787                 __TCP_INC_STATS(net, TCP_MIB_INERRS);
1788         } else {
1789                 tcp_v6_send_reset(NULL, skb);
1790         }
1791
1792 discard_it:
1793         kfree_skb(skb);
1794         return 0;
1795
1796 discard_and_relse:
1797         sk_drops_add(sk, skb);
1798         if (refcounted)
1799                 sock_put(sk);
1800         goto discard_it;
1801
1802 do_time_wait:
1803         if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1804                 inet_twsk_put(inet_twsk(sk));
1805                 goto discard_it;
1806         }
1807
1808         tcp_v6_fill_cb(skb, hdr, th);
1809
1810         if (tcp_checksum_complete(skb)) {
1811                 inet_twsk_put(inet_twsk(sk));
1812                 goto csum_error;
1813         }
1814
1815         switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
1816         case TCP_TW_SYN:
1817         {
1818                 struct sock *sk2;
1819
1820                 sk2 = inet6_lookup_listener(dev_net(skb->dev), &tcp_hashinfo,
1821                                             skb, __tcp_hdrlen(th),
1822                                             &ipv6_hdr(skb)->saddr, th->source,
1823                                             &ipv6_hdr(skb)->daddr,
1824                                             ntohs(th->dest),
1825                                             tcp_v6_iif_l3_slave(skb),
1826                                             sdif);
1827                 if (sk2) {
1828                         struct inet_timewait_sock *tw = inet_twsk(sk);
1829                         inet_twsk_deschedule_put(tw);
1830                         sk = sk2;
1831                         tcp_v6_restore_cb(skb);
1832                         refcounted = false;
1833                         goto process;
1834                 }
1835         }
1836                 /* to ACK */
1837                 fallthrough;
1838         case TCP_TW_ACK:
1839                 tcp_v6_timewait_ack(sk, skb);
1840                 break;
1841         case TCP_TW_RST:
1842                 tcp_v6_send_reset(sk, skb);
1843                 inet_twsk_deschedule_put(inet_twsk(sk));
1844                 goto discard_it;
1845         case TCP_TW_SUCCESS:
1846                 ;
1847         }
1848         goto discard_it;
1849 }
1850
1851 INDIRECT_CALLABLE_SCOPE void tcp_v6_early_demux(struct sk_buff *skb)
1852 {
1853         const struct ipv6hdr *hdr;
1854         const struct tcphdr *th;
1855         struct sock *sk;
1856
1857         if (skb->pkt_type != PACKET_HOST)
1858                 return;
1859
1860         if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct tcphdr)))
1861                 return;
1862
1863         hdr = ipv6_hdr(skb);
1864         th = tcp_hdr(skb);
1865
1866         if (th->doff < sizeof(struct tcphdr) / 4)
1867                 return;
1868
1869         /* Note : We use inet6_iif() here, not tcp_v6_iif() */
1870         sk = __inet6_lookup_established(dev_net(skb->dev), &tcp_hashinfo,
1871                                         &hdr->saddr, th->source,
1872                                         &hdr->daddr, ntohs(th->dest),
1873                                         inet6_iif(skb), inet6_sdif(skb));
1874         if (sk) {
1875                 skb->sk = sk;
1876                 skb->destructor = sock_edemux;
1877                 if (sk_fullsock(sk)) {
1878                         struct dst_entry *dst = READ_ONCE(sk->sk_rx_dst);
1879
1880                         if (dst)
1881                                 dst = dst_check(dst, tcp_inet6_sk(sk)->rx_dst_cookie);
1882                         if (dst &&
1883                             inet_sk(sk)->rx_dst_ifindex == skb->skb_iif)
1884                                 skb_dst_set_noref(skb, dst);
1885                 }
1886         }
1887 }
1888
1889 static struct timewait_sock_ops tcp6_timewait_sock_ops = {
1890         .twsk_obj_size  = sizeof(struct tcp6_timewait_sock),
1891         .twsk_unique    = tcp_twsk_unique,
1892         .twsk_destructor = tcp_twsk_destructor,
1893 };
1894
1895 INDIRECT_CALLABLE_SCOPE void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb)
1896 {
1897         struct ipv6_pinfo *np = inet6_sk(sk);
1898
1899         __tcp_v6_send_check(skb, &np->saddr, &sk->sk_v6_daddr);
1900 }
1901
1902 const struct inet_connection_sock_af_ops ipv6_specific = {
1903         .queue_xmit        = inet6_csk_xmit,
1904         .send_check        = tcp_v6_send_check,
1905         .rebuild_header    = inet6_sk_rebuild_header,
1906         .sk_rx_dst_set     = inet6_sk_rx_dst_set,
1907         .conn_request      = tcp_v6_conn_request,
1908         .syn_recv_sock     = tcp_v6_syn_recv_sock,
1909         .net_header_len    = sizeof(struct ipv6hdr),
1910         .net_frag_header_len = sizeof(struct frag_hdr),
1911         .setsockopt        = ipv6_setsockopt,
1912         .getsockopt        = ipv6_getsockopt,
1913         .addr2sockaddr     = inet6_csk_addr2sockaddr,
1914         .sockaddr_len      = sizeof(struct sockaddr_in6),
1915         .mtu_reduced       = tcp_v6_mtu_reduced,
1916 };
1917
1918 #ifdef CONFIG_TCP_MD5SIG
1919 static const struct tcp_sock_af_ops tcp_sock_ipv6_specific = {
1920         .md5_lookup     =       tcp_v6_md5_lookup,
1921         .calc_md5_hash  =       tcp_v6_md5_hash_skb,
1922         .md5_parse      =       tcp_v6_parse_md5_keys,
1923 };
1924 #endif
1925
1926 /*
1927  *      TCP over IPv4 via INET6 API
1928  */
1929 static const struct inet_connection_sock_af_ops ipv6_mapped = {
1930         .queue_xmit        = ip_queue_xmit,
1931         .send_check        = tcp_v4_send_check,
1932         .rebuild_header    = inet_sk_rebuild_header,
1933         .sk_rx_dst_set     = inet_sk_rx_dst_set,
1934         .conn_request      = tcp_v6_conn_request,
1935         .syn_recv_sock     = tcp_v6_syn_recv_sock,
1936         .net_header_len    = sizeof(struct iphdr),
1937         .setsockopt        = ipv6_setsockopt,
1938         .getsockopt        = ipv6_getsockopt,
1939         .addr2sockaddr     = inet6_csk_addr2sockaddr,
1940         .sockaddr_len      = sizeof(struct sockaddr_in6),
1941         .mtu_reduced       = tcp_v4_mtu_reduced,
1942 };
1943
1944 #ifdef CONFIG_TCP_MD5SIG
1945 static const struct tcp_sock_af_ops tcp_sock_ipv6_mapped_specific = {
1946         .md5_lookup     =       tcp_v4_md5_lookup,
1947         .calc_md5_hash  =       tcp_v4_md5_hash_skb,
1948         .md5_parse      =       tcp_v6_parse_md5_keys,
1949 };
1950 #endif
1951
1952 /* NOTE: A lot of things set to zero explicitly by call to
1953  *       sk_alloc() so need not be done here.
1954  */
1955 static int tcp_v6_init_sock(struct sock *sk)
1956 {
1957         struct inet_connection_sock *icsk = inet_csk(sk);
1958
1959         tcp_init_sock(sk);
1960
1961         icsk->icsk_af_ops = &ipv6_specific;
1962
1963 #ifdef CONFIG_TCP_MD5SIG
1964         tcp_sk(sk)->af_specific = &tcp_sock_ipv6_specific;
1965 #endif
1966
1967         return 0;
1968 }
1969
1970 static void tcp_v6_destroy_sock(struct sock *sk)
1971 {
1972         tcp_v4_destroy_sock(sk);
1973         inet6_destroy_sock(sk);
1974 }
1975
1976 #ifdef CONFIG_PROC_FS
1977 /* Proc filesystem TCPv6 sock list dumping. */
1978 static void get_openreq6(struct seq_file *seq,
1979                          const struct request_sock *req, int i)
1980 {
1981         long ttd = req->rsk_timer.expires - jiffies;
1982         const struct in6_addr *src = &inet_rsk(req)->ir_v6_loc_addr;
1983         const struct in6_addr *dest = &inet_rsk(req)->ir_v6_rmt_addr;
1984
1985         if (ttd < 0)
1986                 ttd = 0;
1987
1988         seq_printf(seq,
1989                    "%4d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
1990                    "%02X %08X:%08X %02X:%08lX %08X %5u %8d %d %d %pK\n",
1991                    i,
1992                    src->s6_addr32[0], src->s6_addr32[1],
1993                    src->s6_addr32[2], src->s6_addr32[3],
1994                    inet_rsk(req)->ir_num,
1995                    dest->s6_addr32[0], dest->s6_addr32[1],
1996                    dest->s6_addr32[2], dest->s6_addr32[3],
1997                    ntohs(inet_rsk(req)->ir_rmt_port),
1998                    TCP_SYN_RECV,
1999                    0, 0, /* could print option size, but that is af dependent. */
2000                    1,   /* timers active (only the expire timer) */
2001                    jiffies_to_clock_t(ttd),
2002                    req->num_timeout,
2003                    from_kuid_munged(seq_user_ns(seq),
2004                                     sock_i_uid(req->rsk_listener)),
2005                    0,  /* non standard timer */
2006                    0, /* open_requests have no inode */
2007                    0, req);
2008 }
2009
2010 static void get_tcp6_sock(struct seq_file *seq, struct sock *sp, int i)
2011 {
2012         const struct in6_addr *dest, *src;
2013         __u16 destp, srcp;
2014         int timer_active;
2015         unsigned long timer_expires;
2016         const struct inet_sock *inet = inet_sk(sp);
2017         const struct tcp_sock *tp = tcp_sk(sp);
2018         const struct inet_connection_sock *icsk = inet_csk(sp);
2019         const struct fastopen_queue *fastopenq = &icsk->icsk_accept_queue.fastopenq;
2020         int rx_queue;
2021         int state;
2022
2023         dest  = &sp->sk_v6_daddr;
2024         src   = &sp->sk_v6_rcv_saddr;
2025         destp = ntohs(inet->inet_dport);
2026         srcp  = ntohs(inet->inet_sport);
2027
2028         if (icsk->icsk_pending == ICSK_TIME_RETRANS ||
2029             icsk->icsk_pending == ICSK_TIME_REO_TIMEOUT ||
2030             icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) {
2031                 timer_active    = 1;
2032                 timer_expires   = icsk->icsk_timeout;
2033         } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
2034                 timer_active    = 4;
2035                 timer_expires   = icsk->icsk_timeout;
2036         } else if (timer_pending(&sp->sk_timer)) {
2037                 timer_active    = 2;
2038                 timer_expires   = sp->sk_timer.expires;
2039         } else {
2040                 timer_active    = 0;
2041                 timer_expires = jiffies;
2042         }
2043
2044         state = inet_sk_state_load(sp);
2045         if (state == TCP_LISTEN)
2046                 rx_queue = READ_ONCE(sp->sk_ack_backlog);
2047         else
2048                 /* Because we don't lock the socket,
2049                  * we might find a transient negative value.
2050                  */
2051                 rx_queue = max_t(int, READ_ONCE(tp->rcv_nxt) -
2052                                       READ_ONCE(tp->copied_seq), 0);
2053
2054         seq_printf(seq,
2055                    "%4d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
2056                    "%02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %lu %lu %u %u %d\n",
2057                    i,
2058                    src->s6_addr32[0], src->s6_addr32[1],
2059                    src->s6_addr32[2], src->s6_addr32[3], srcp,
2060                    dest->s6_addr32[0], dest->s6_addr32[1],
2061                    dest->s6_addr32[2], dest->s6_addr32[3], destp,
2062                    state,
2063                    READ_ONCE(tp->write_seq) - tp->snd_una,
2064                    rx_queue,
2065                    timer_active,
2066                    jiffies_delta_to_clock_t(timer_expires - jiffies),
2067                    icsk->icsk_retransmits,
2068                    from_kuid_munged(seq_user_ns(seq), sock_i_uid(sp)),
2069                    icsk->icsk_probes_out,
2070                    sock_i_ino(sp),
2071                    refcount_read(&sp->sk_refcnt), sp,
2072                    jiffies_to_clock_t(icsk->icsk_rto),
2073                    jiffies_to_clock_t(icsk->icsk_ack.ato),
2074                    (icsk->icsk_ack.quick << 1) | inet_csk_in_pingpong_mode(sp),
2075                    tp->snd_cwnd,
2076                    state == TCP_LISTEN ?
2077                         fastopenq->max_qlen :
2078                         (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh)
2079                    );
2080 }
2081
2082 static void get_timewait6_sock(struct seq_file *seq,
2083                                struct inet_timewait_sock *tw, int i)
2084 {
2085         long delta = tw->tw_timer.expires - jiffies;
2086         const struct in6_addr *dest, *src;
2087         __u16 destp, srcp;
2088
2089         dest = &tw->tw_v6_daddr;
2090         src  = &tw->tw_v6_rcv_saddr;
2091         destp = ntohs(tw->tw_dport);
2092         srcp  = ntohs(tw->tw_sport);
2093
2094         seq_printf(seq,
2095                    "%4d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
2096                    "%02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK\n",
2097                    i,
2098                    src->s6_addr32[0], src->s6_addr32[1],
2099                    src->s6_addr32[2], src->s6_addr32[3], srcp,
2100                    dest->s6_addr32[0], dest->s6_addr32[1],
2101                    dest->s6_addr32[2], dest->s6_addr32[3], destp,
2102                    tw->tw_substate, 0, 0,
2103                    3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,
2104                    refcount_read(&tw->tw_refcnt), tw);
2105 }
2106
2107 static int tcp6_seq_show(struct seq_file *seq, void *v)
2108 {
2109         struct tcp_iter_state *st;
2110         struct sock *sk = v;
2111
2112         if (v == SEQ_START_TOKEN) {
2113                 seq_puts(seq,
2114                          "  sl  "
2115                          "local_address                         "
2116                          "remote_address                        "
2117                          "st tx_queue rx_queue tr tm->when retrnsmt"
2118                          "   uid  timeout inode\n");
2119                 goto out;
2120         }
2121         st = seq->private;
2122
2123         if (sk->sk_state == TCP_TIME_WAIT)
2124                 get_timewait6_sock(seq, v, st->num);
2125         else if (sk->sk_state == TCP_NEW_SYN_RECV)
2126                 get_openreq6(seq, v, st->num);
2127         else
2128                 get_tcp6_sock(seq, v, st->num);
2129 out:
2130         return 0;
2131 }
2132
2133 static const struct seq_operations tcp6_seq_ops = {
2134         .show           = tcp6_seq_show,
2135         .start          = tcp_seq_start,
2136         .next           = tcp_seq_next,
2137         .stop           = tcp_seq_stop,
2138 };
2139
2140 static struct tcp_seq_afinfo tcp6_seq_afinfo = {
2141         .family         = AF_INET6,
2142 };
2143
2144 int __net_init tcp6_proc_init(struct net *net)
2145 {
2146         if (!proc_create_net_data("tcp6", 0444, net->proc_net, &tcp6_seq_ops,
2147                         sizeof(struct tcp_iter_state), &tcp6_seq_afinfo))
2148                 return -ENOMEM;
2149         return 0;
2150 }
2151
2152 void tcp6_proc_exit(struct net *net)
2153 {
2154         remove_proc_entry("tcp6", net->proc_net);
2155 }
2156 #endif
2157
2158 struct proto tcpv6_prot = {
2159         .name                   = "TCPv6",
2160         .owner                  = THIS_MODULE,
2161         .close                  = tcp_close,
2162         .pre_connect            = tcp_v6_pre_connect,
2163         .connect                = tcp_v6_connect,
2164         .disconnect             = tcp_disconnect,
2165         .accept                 = inet_csk_accept,
2166         .ioctl                  = tcp_ioctl,
2167         .init                   = tcp_v6_init_sock,
2168         .destroy                = tcp_v6_destroy_sock,
2169         .shutdown               = tcp_shutdown,
2170         .setsockopt             = tcp_setsockopt,
2171         .getsockopt             = tcp_getsockopt,
2172         .bpf_bypass_getsockopt  = tcp_bpf_bypass_getsockopt,
2173         .keepalive              = tcp_set_keepalive,
2174         .recvmsg                = tcp_recvmsg,
2175         .sendmsg                = tcp_sendmsg,
2176         .sendpage               = tcp_sendpage,
2177         .backlog_rcv            = tcp_v6_do_rcv,
2178         .release_cb             = tcp_release_cb,
2179         .hash                   = inet6_hash,
2180         .unhash                 = inet_unhash,
2181         .get_port               = inet_csk_get_port,
2182 #ifdef CONFIG_BPF_SYSCALL
2183         .psock_update_sk_prot   = tcp_bpf_update_proto,
2184 #endif
2185         .enter_memory_pressure  = tcp_enter_memory_pressure,
2186         .leave_memory_pressure  = tcp_leave_memory_pressure,
2187         .stream_memory_free     = tcp_stream_memory_free,
2188         .sockets_allocated      = &tcp_sockets_allocated,
2189         .memory_allocated       = &tcp_memory_allocated,
2190         .memory_pressure        = &tcp_memory_pressure,
2191         .orphan_count           = &tcp_orphan_count,
2192         .sysctl_mem             = sysctl_tcp_mem,
2193         .sysctl_wmem_offset     = offsetof(struct net, ipv4.sysctl_tcp_wmem),
2194         .sysctl_rmem_offset     = offsetof(struct net, ipv4.sysctl_tcp_rmem),
2195         .max_header             = MAX_TCP_HEADER,
2196         .obj_size               = sizeof(struct tcp6_sock),
2197         .slab_flags             = SLAB_TYPESAFE_BY_RCU,
2198         .twsk_prot              = &tcp6_timewait_sock_ops,
2199         .rsk_prot               = &tcp6_request_sock_ops,
2200         .h.hashinfo             = &tcp_hashinfo,
2201         .no_autobind            = true,
2202         .diag_destroy           = tcp_abort,
2203 };
2204 EXPORT_SYMBOL_GPL(tcpv6_prot);
2205
2206 /* thinking of making this const? Don't.
2207  * early_demux can change based on sysctl.
2208  */
2209 static struct inet6_protocol tcpv6_protocol = {
2210         .early_demux    =       tcp_v6_early_demux,
2211         .early_demux_handler =  tcp_v6_early_demux,
2212         .handler        =       tcp_v6_rcv,
2213         .err_handler    =       tcp_v6_err,
2214         .flags          =       INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
2215 };
2216
2217 static struct inet_protosw tcpv6_protosw = {
2218         .type           =       SOCK_STREAM,
2219         .protocol       =       IPPROTO_TCP,
2220         .prot           =       &tcpv6_prot,
2221         .ops            =       &inet6_stream_ops,
2222         .flags          =       INET_PROTOSW_PERMANENT |
2223                                 INET_PROTOSW_ICSK,
2224 };
2225
2226 static int __net_init tcpv6_net_init(struct net *net)
2227 {
2228         return inet_ctl_sock_create(&net->ipv6.tcp_sk, PF_INET6,
2229                                     SOCK_RAW, IPPROTO_TCP, net);
2230 }
2231
2232 static void __net_exit tcpv6_net_exit(struct net *net)
2233 {
2234         inet_ctl_sock_destroy(net->ipv6.tcp_sk);
2235 }
2236
2237 static void __net_exit tcpv6_net_exit_batch(struct list_head *net_exit_list)
2238 {
2239         inet_twsk_purge(&tcp_hashinfo, AF_INET6);
2240 }
2241
2242 static struct pernet_operations tcpv6_net_ops = {
2243         .init       = tcpv6_net_init,
2244         .exit       = tcpv6_net_exit,
2245         .exit_batch = tcpv6_net_exit_batch,
2246 };
2247
2248 int __init tcpv6_init(void)
2249 {
2250         int ret;
2251
2252         ret = inet6_add_protocol(&tcpv6_protocol, IPPROTO_TCP);
2253         if (ret)
2254                 goto out;
2255
2256         /* register inet6 protocol */
2257         ret = inet6_register_protosw(&tcpv6_protosw);
2258         if (ret)
2259                 goto out_tcpv6_protocol;
2260
2261         ret = register_pernet_subsys(&tcpv6_net_ops);
2262         if (ret)
2263                 goto out_tcpv6_protosw;
2264
2265         ret = mptcpv6_init();
2266         if (ret)
2267                 goto out_tcpv6_pernet_subsys;
2268
2269 out:
2270         return ret;
2271
2272 out_tcpv6_pernet_subsys:
2273         unregister_pernet_subsys(&tcpv6_net_ops);
2274 out_tcpv6_protosw:
2275         inet6_unregister_protosw(&tcpv6_protosw);
2276 out_tcpv6_protocol:
2277         inet6_del_protocol(&tcpv6_protocol, IPPROTO_TCP);
2278         goto out;
2279 }
2280
2281 void tcpv6_exit(void)
2282 {
2283         unregister_pernet_subsys(&tcpv6_net_ops);
2284         inet6_unregister_protosw(&tcpv6_protosw);
2285         inet6_del_protocol(&tcpv6_protocol, IPPROTO_TCP);
2286 }