net/ipv4/tcp_ipv4.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              Implementation of the Transmission Control Protocol(TCP).
   7  *
   8  *              IPv4 specific functions
   9  *
  10  *
  11  *              code split from:
  12  *              linux/ipv4/tcp.c
  13  *              linux/ipv4/tcp_input.c
  14  *              linux/ipv4/tcp_output.c
  15  *
  16  *              See tcp.c for author information
  17  *
  18  *      This program is free software; you can redistribute it and/or
  19  *      modify it under the terms of the GNU General Public License
  20  *      as published by the Free Software Foundation; either version
  21  *      2 of the License, or (at your option) any later version.
  22  */
  23
  24 /*
  25  * Changes:
  26  *              David S. Miller :       New socket lookup architecture.
  27  *                                      This code is dedicated to John Dyson.
  28  *              David S. Miller :       Change semantics of established hash,
  29  *                                      half is devoted to TIME_WAIT sockets
  30  *                                      and the rest go in the other half.
  31  *              Andi Kleen :            Add support for syncookies and fixed
  32  *                                      some bugs: ip options weren't passed to
  33  *                                      the TCP layer, missed a check for an
  34  *                                      ACK bit.
  35  *              Andi Kleen :            Implemented fast path mtu discovery.
  36  *                                      Fixed many serious bugs in the
  37  *                                      request_sock handling and moved
  38  *                                      most of it into the af independent code.
  39  *                                      Added tail drop and some other bugfixes.
  40  *                                      Added new listen semantics.
  41  *              Mike McLagan    :       Routing by source
  42  *      Juan Jose Ciarlante:            ip_dynaddr bits
  43  *              Andi Kleen:             various fixes.
  44  *      Vitaly E. Lavrov        :       Transparent proxy revived after year
  45  *                                      coma.
  46  *      Andi Kleen              :       Fix new listen.
  47  *      Andi Kleen              :       Fix accept error reporting.
  48  *      YOSHIFUJI Hideaki @USAGI and:   Support IPV6_V6ONLY socket option, which
  49  *      Alexey Kuznetsov                allow both IPv4 and IPv6 sockets to bind
  50  *                                      a single port at the same time.
  51  */
  52
  53 #define pr_fmt(fmt) "TCP: " fmt
  54
  55 #include <linux/bottom_half.h>
  56 #include <linux/types.h>
  57 #include <linux/fcntl.h>
  58 #include <linux/module.h>
  59 #include <linux/random.h>
  60 #include <linux/cache.h>
  61 #include <linux/jhash.h>
  62 #include <linux/init.h>
  63 #include <linux/times.h>
  64 #include <linux/slab.h>
  65
  66 #include <net/net_namespace.h>
  67 #include <net/icmp.h>
  68 #include <net/inet_hashtables.h>
  69 #include <net/tcp.h>
  70 #include <net/transp_v6.h>
  71 #include <net/ipv6.h>
  72 #include <net/inet_common.h>
  73 #include <net/timewait_sock.h>
  74 #include <net/xfrm.h>
  75 #include <net/secure_seq.h>
  76 #include <net/tcp_memcontrol.h>
  77 #include <net/busy_poll.h>
  78
  79 #include <linux/inet.h>
  80 #include <linux/ipv6.h>
  81 #include <linux/stddef.h>
  82 #include <linux/proc_fs.h>
  83 #include <linux/seq_file.h>
  84
  85 #include <linux/crypto.h>
  86 #include <linux/scatterlist.h>
  87
  88 int sysctl_tcp_tw_reuse __read_mostly;
  89 int sysctl_tcp_low_latency __read_mostly;
  90 EXPORT_SYMBOL(sysctl_tcp_low_latency);
  91
  92 #ifdef CONFIG_TCP_MD5SIG
  93 static int tcp_v4_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key,
  94                                __be32 daddr, __be32 saddr, const struct tcphdr *th);
  95 #endif
  96
  97 struct inet_hashinfo tcp_hashinfo;
  98 EXPORT_SYMBOL(tcp_hashinfo);
  99
 100 static  __u32 tcp_v4_init_sequence(const struct sk_buff *skb)
 101 {
 102         return secure_tcp_sequence_number(ip_hdr(skb)->daddr,
 103                                           ip_hdr(skb)->saddr,
 104                                           tcp_hdr(skb)->dest,
 105                                           tcp_hdr(skb)->source);
 106 }
 107
 108 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
 109 {
 110         const struct tcp_timewait_sock *tcptw = tcp_twsk(sktw);
 111         struct tcp_sock *tp = tcp_sk(sk);
 112
 113         /* With PAWS, it is safe from the viewpoint
 114            of data integrity. Even without PAWS it is safe provided sequence
 115            spaces do not overlap i.e. at data rates <= 80Mbit/sec.
 116
 117            Actually, the idea is close to VJ's one, only timestamp cache is
 118            held not per host, but per port pair and TW bucket is used as state
 119            holder.
 120
 121            If TW bucket has been already destroyed we fall back to VJ's scheme
 122            and use initial timestamp retrieved from peer table.
 123          */
 124         if (tcptw->tw_ts_recent_stamp &&
 125             (!twp || (sysctl_tcp_tw_reuse &&
 126                              get_seconds() - tcptw->tw_ts_recent_stamp > 1))) {
 127                 tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2;
 128                 if (tp->write_seq == 0)
 129                         tp->write_seq = 1;
 130                 tp->rx_opt.ts_recent       = tcptw->tw_ts_recent;
 131                 tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
 132                 sock_hold(sktw);
 133                 return 1;
 134         }
 135
 136         return 0;
 137 }
 138 EXPORT_SYMBOL_GPL(tcp_twsk_unique);
 139
 140 /* This will initiate an outgoing connection. */
 141 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 142 {
 143         struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
 144         struct inet_sock *inet = inet_sk(sk);
 145         struct tcp_sock *tp = tcp_sk(sk);
 146         __be16 orig_sport, orig_dport;
 147         __be32 daddr, nexthop;
 148         struct flowi4 *fl4;
 149         struct rtable *rt;
 150         int err;
 151         struct ip_options_rcu *inet_opt;
 152
 153         if (addr_len < sizeof(struct sockaddr_in))
 154                 return -EINVAL;
 155
 156         if (usin->sin_family != AF_INET)
 157                 return -EAFNOSUPPORT;
 158
 159         nexthop = daddr = usin->sin_addr.s_addr;
 160         inet_opt = rcu_dereference_protected(inet->inet_opt,
 161                                              sock_owned_by_user(sk));
 162         if (inet_opt && inet_opt->opt.srr) {
 163                 if (!daddr)
 164                         return -EINVAL;
 165                 nexthop = inet_opt->opt.faddr;
 166         }
 167
 168         orig_sport = inet->inet_sport;
 169         orig_dport = usin->sin_port;
 170         fl4 = &inet->cork.fl.u.ip4;
 171         rt = ip_route_connect(fl4, nexthop, inet->inet_saddr,
 172                               RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
 173                               IPPROTO_TCP,
 174                               orig_sport, orig_dport, sk);
 175         if (IS_ERR(rt)) {
 176                 err = PTR_ERR(rt);
 177                 if (err == -ENETUNREACH)
 178                         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
 179                 return err;
 180         }
 181
 182         if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
 183                 ip_rt_put(rt);
 184                 return -ENETUNREACH;
 185         }
 186
 187         if (!inet_opt || !inet_opt->opt.srr)
 188                 daddr = fl4->daddr;
 189
 190         if (!inet->inet_saddr)
 191                 inet->inet_saddr = fl4->saddr;
 192         sk_rcv_saddr_set(sk, inet->inet_saddr);
 193
 194         if (tp->rx_opt.ts_recent_stamp && inet->inet_daddr != daddr) {
 195                 /* Reset inherited state */
 196                 tp->rx_opt.ts_recent       = 0;
 197                 tp->rx_opt.ts_recent_stamp = 0;
 198                 if (likely(!tp->repair))
 199                         tp->write_seq      = 0;
 200         }
 201
 202         if (tcp_death_row.sysctl_tw_recycle &&
 203             !tp->rx_opt.ts_recent_stamp && fl4->daddr == daddr)
 204                 tcp_fetch_timewait_stamp(sk, &rt->dst);
 205
 206         inet->inet_dport = usin->sin_port;
 207         sk_daddr_set(sk, daddr);
 208
 209         inet_csk(sk)->icsk_ext_hdr_len = 0;
 210         if (inet_opt)
 211                 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
 212
 213         tp->rx_opt.mss_clamp = TCP_MSS_DEFAULT;
 214
 215         /* Socket identity is still unknown (sport may be zero).
 216          * However we set state to SYN-SENT and not releasing socket
 217          * lock select source port, enter ourselves into the hash tables and
 218          * complete initialization after this.
 219          */
 220         tcp_set_state(sk, TCP_SYN_SENT);
 221         err = inet_hash_connect(&tcp_death_row, sk);
 222         if (err)
 223                 goto failure;
 224
 225         inet_set_txhash(sk);
 226
 227         rt = ip_route_newports(fl4, rt, orig_sport, orig_dport,
 228                                inet->inet_sport, inet->inet_dport, sk);
 229         if (IS_ERR(rt)) {
 230                 err = PTR_ERR(rt);
 231                 rt = NULL;
 232                 goto failure;
 233         }
 234         /* OK, now commit destination to socket.  */
 235         sk->sk_gso_type = SKB_GSO_TCPV4;
 236         sk_setup_caps(sk, &rt->dst);
 237
 238         if (!tp->write_seq && likely(!tp->repair))
 239                 tp->write_seq = secure_tcp_sequence_number(inet->inet_saddr,
 240                                                            inet->inet_daddr,
 241                                                            inet->inet_sport,
 242                                                            usin->sin_port);
 243
 244         inet->inet_id = tp->write_seq ^ jiffies;
 245
 246         err = tcp_connect(sk);
 247
 248         rt = NULL;
 249         if (err)
 250                 goto failure;
 251
 252         return 0;
 253
 254 failure:
 255         /*
 256          * This unhashes the socket and releases the local port,
 257          * if necessary.
 258          */
 259         tcp_set_state(sk, TCP_CLOSE);
 260         ip_rt_put(rt);
 261         sk->sk_route_caps = 0;
 262         inet->inet_dport = 0;
 263         return err;
 264 }
 265 EXPORT_SYMBOL(tcp_v4_connect);
 266
 267 /*
 268  * This routine reacts to ICMP_FRAG_NEEDED mtu indications as defined in RFC1191.
 269  * It can be called through tcp_release_cb() if socket was owned by user
 270  * at the time tcp_v4_err() was called to handle ICMP message.
 271  */
 272 void tcp_v4_mtu_reduced(struct sock *sk)
 273 {
 274         struct dst_entry *dst;
 275         struct inet_sock *inet = inet_sk(sk);
 276         u32 mtu = tcp_sk(sk)->mtu_info;
 277
 278         dst = inet_csk_update_pmtu(sk, mtu);
 279         if (!dst)
 280                 return;
 281
 282         /* Something is about to be wrong... Remember soft error
 283          * for the case, if this connection will not able to recover.
 284          */
 285         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
 286                 sk->sk_err_soft = EMSGSIZE;
 287
 288         mtu = dst_mtu(dst);
 289
 290         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
 291             ip_sk_accept_pmtu(sk) &&
 292             inet_csk(sk)->icsk_pmtu_cookie > mtu) {
 293                 tcp_sync_mss(sk, mtu);
 294
 295                 /* Resend the TCP packet because it's
 296                  * clear that the old packet has been
 297                  * dropped. This is the new "fast" path mtu
 298                  * discovery.
 299                  */
 300                 tcp_simple_retransmit(sk);
 301         } /* else let the usual retransmit timer handle it */
 302 }
 303 EXPORT_SYMBOL(tcp_v4_mtu_reduced);
 304
 305 static void do_redirect(struct sk_buff *skb, struct sock *sk)
 306 {
 307         struct dst_entry *dst = __sk_dst_check(sk, 0);
 308
 309         if (dst)
 310                 dst->ops->redirect(dst, sk, skb);
 311 }
 312
 313
 314 /* handle ICMP messages on TCP_NEW_SYN_RECV request sockets */
 315 void tcp_req_err(struct sock *sk, u32 seq)
 316 {
 317         struct request_sock *req = inet_reqsk(sk);
 318         struct net *net = sock_net(sk);
 319
 320         /* ICMPs are not backlogged, hence we cannot get
 321          * an established socket here.
 322          */
 323         WARN_ON(req->sk);
 324
 325         if (seq != tcp_rsk(req)->snt_isn) {
 326                 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
 327                 reqsk_put(req);
 328         } else {
 329                 /*
 330                  * Still in SYN_RECV, just remove it silently.
 331                  * There is no good way to pass the error to the newly
 332                  * created socket, and POSIX does not want network
 333                  * errors returned from accept().
 334                  */
 335                 NET_INC_STATS_BH(net, LINUX_MIB_LISTENDROPS);
 336                 inet_csk_reqsk_queue_drop(req->rsk_listener, req);
 337         }
 338 }
 339 EXPORT_SYMBOL(tcp_req_err);
 340
 341 /*
 342  * This routine is called by the ICMP module when it gets some
 343  * sort of error condition.  If err < 0 then the socket should
 344  * be closed and the error returned to the user.  If err > 0
 345  * it's just the icmp type << 8 | icmp code.  After adjustment
 346  * header points to the first 8 bytes of the tcp header.  We need
 347  * to find the appropriate port.
 348  *
 349  * The locking strategy used here is very "optimistic". When
 350  * someone else accesses the socket the ICMP is just dropped
 351  * and for some paths there is no check at all.
 352  * A more general error queue to queue errors for later handling
 353  * is probably better.
 354  *
 355  */
 356
 357 void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
 358 {
 359         const struct iphdr *iph = (const struct iphdr *)icmp_skb->data;
 360         struct tcphdr *th = (struct tcphdr *)(icmp_skb->data + (iph->ihl << 2));
 361         struct inet_connection_sock *icsk;
 362         struct tcp_sock *tp;
 363         struct inet_sock *inet;
 364         const int type = icmp_hdr(icmp_skb)->type;
 365         const int code = icmp_hdr(icmp_skb)->code;
 366         struct sock *sk;
 367         struct sk_buff *skb;
 368         struct request_sock *fastopen;
 369         __u32 seq, snd_una;
 370         __u32 remaining;
 371         int err;
 372         struct net *net = dev_net(icmp_skb->dev);
 373
 374         sk = __inet_lookup_established(net, &tcp_hashinfo, iph->daddr,
 375                                        th->dest, iph->saddr, ntohs(th->source),
 376                                        inet_iif(icmp_skb));
 377         if (!sk) {
 378                 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 379                 return;
 380         }
 381         if (sk->sk_state == TCP_TIME_WAIT) {
 382                 inet_twsk_put(inet_twsk(sk));
 383                 return;
 384         }
 385         seq = ntohl(th->seq);
 386         if (sk->sk_state == TCP_NEW_SYN_RECV)
 387                 return tcp_req_err(sk, seq);
 388
 389         bh_lock_sock(sk);
 390         /* If too many ICMPs get dropped on busy
 391          * servers this needs to be solved differently.
 392          * We do take care of PMTU discovery (RFC1191) special case :
 393          * we can receive locally generated ICMP messages while socket is held.
 394          */
 395         if (sock_owned_by_user(sk)) {
 396                 if (!(type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED))
 397                         NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
 398         }
 399         if (sk->sk_state == TCP_CLOSE)
 400                 goto out;
 401
 402         if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) {
 403                 NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
 404                 goto out;
 405         }
 406
 407         icsk = inet_csk(sk);
 408         tp = tcp_sk(sk);
 409         /* XXX (TFO) - tp->snd_una should be ISN (tcp_create_openreq_child() */
 410         fastopen = tp->fastopen_rsk;
 411         snd_una = fastopen ? tcp_rsk(fastopen)->snt_isn : tp->snd_una;
 412         if (sk->sk_state != TCP_LISTEN &&
 413             !between(seq, snd_una, tp->snd_nxt)) {
 414                 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
 415                 goto out;
 416         }
 417
 418         switch (type) {
 419         case ICMP_REDIRECT:
 420                 do_redirect(icmp_skb, sk);
 421                 goto out;
 422         case ICMP_SOURCE_QUENCH:
 423                 /* Just silently ignore these. */
 424                 goto out;
 425         case ICMP_PARAMETERPROB:
 426                 err = EPROTO;
 427                 break;
 428         case ICMP_DEST_UNREACH:
 429                 if (code > NR_ICMP_UNREACH)
 430                         goto out;
 431
 432                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
 433                         /* We are not interested in TCP_LISTEN and open_requests
 434                          * (SYN-ACKs send out by Linux are always <576bytes so
 435                          * they should go through unfragmented).
 436                          */
 437                         if (sk->sk_state == TCP_LISTEN)
 438                                 goto out;
 439
 440                         tp->mtu_info = info;
 441                         if (!sock_owned_by_user(sk)) {
 442                                 tcp_v4_mtu_reduced(sk);
 443                         } else {
 444                                 if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED, &tp->tsq_flags))
 445                                         sock_hold(sk);
 446                         }
 447                         goto out;
 448                 }
 449
 450                 err = icmp_err_convert[code].errno;
 451                 /* check if icmp_skb allows revert of backoff
 452                  * (see draft-zimmermann-tcp-lcd) */
 453                 if (code != ICMP_NET_UNREACH && code != ICMP_HOST_UNREACH)
 454                         break;
 455                 if (seq != tp->snd_una  || !icsk->icsk_retransmits ||
 456                     !icsk->icsk_backoff || fastopen)
 457                         break;
 458
 459                 if (sock_owned_by_user(sk))
 460                         break;
 461
 462                 icsk->icsk_backoff--;
 463                 icsk->icsk_rto = tp->srtt_us ? __tcp_set_rto(tp) :
 464                                                TCP_TIMEOUT_INIT;
 465                 icsk->icsk_rto = inet_csk_rto_backoff(icsk, TCP_RTO_MAX);
 466
 467                 skb = tcp_write_queue_head(sk);
 468                 BUG_ON(!skb);
 469
 470                 remaining = icsk->icsk_rto -
 471                             min(icsk->icsk_rto,
 472                                 tcp_time_stamp - tcp_skb_timestamp(skb));
 473
 474                 if (remaining) {
 475                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
 476                                                   remaining, TCP_RTO_MAX);
 477                 } else {
 478                         /* RTO revert clocked out retransmission.
 479                          * Will retransmit now */
 480                         tcp_retransmit_timer(sk);
 481                 }
 482
 483                 break;
 484         case ICMP_TIME_EXCEEDED:
 485                 err = EHOSTUNREACH;
 486                 break;
 487         default:
 488                 goto out;
 489         }
 490
 491         switch (sk->sk_state) {
 492         case TCP_SYN_SENT:
 493         case TCP_SYN_RECV:
 494                 /* Only in fast or simultaneous open. If a fast open socket is
 495                  * is already accepted it is treated as a connected one below.
 496                  */
 497                 if (fastopen && !fastopen->sk)
 498                         break;
 499
 500                 if (!sock_owned_by_user(sk)) {
 501                         sk->sk_err = err;
 502
 503                         sk->sk_error_report(sk);
 504
 505                         tcp_done(sk);
 506                 } else {
 507                         sk->sk_err_soft = err;
 508                 }
 509                 goto out;
 510         }
 511
 512         /* If we've already connected we will keep trying
 513          * until we time out, or the user gives up.
 514          *
 515          * rfc1122 4.2.3.9 allows to consider as hard errors
 516          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
 517          * but it is obsoleted by pmtu discovery).
 518          *
 519          * Note, that in modern internet, where routing is unreliable
 520          * and in each dark corner broken firewalls sit, sending random
 521          * errors ordered by their masters even this two messages finally lose
 522          * their original sense (even Linux sends invalid PORT_UNREACHs)
 523          *
 524          * Now we are in compliance with RFCs.
 525          *                                                      --ANK (980905)
 526          */
 527
 528         inet = inet_sk(sk);
 529         if (!sock_owned_by_user(sk) && inet->recverr) {
 530                 sk->sk_err = err;
 531                 sk->sk_error_report(sk);
 532         } else  { /* Only an error on timeout */
 533                 sk->sk_err_soft = err;
 534         }
 535
 536 out:
 537         bh_unlock_sock(sk);
 538         sock_put(sk);
 539 }
 540
 541 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr)
 542 {
 543         struct tcphdr *th = tcp_hdr(skb);
 544
 545         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 546                 th->check = ~tcp_v4_check(skb->len, saddr, daddr, 0);
 547                 skb->csum_start = skb_transport_header(skb) - skb->head;
 548                 skb->csum_offset = offsetof(struct tcphdr, check);
 549         } else {
 550                 th->check = tcp_v4_check(skb->len, saddr, daddr,
 551                                          csum_partial(th,
 552                                                       th->doff << 2,
 553                                                       skb->csum));
 554         }
 555 }
 556
 557 /* This routine computes an IPv4 TCP checksum. */
 558 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb)
 559 {
 560         const struct inet_sock *inet = inet_sk(sk);
 561
 562         __tcp_v4_send_check(skb, inet->inet_saddr, inet->inet_daddr);
 563 }
 564 EXPORT_SYMBOL(tcp_v4_send_check);
 565
 566 /*
 567  *      This routine will send an RST to the other tcp.
 568  *
 569  *      Someone asks: why I NEVER use socket parameters (TOS, TTL etc.)
 570  *                    for reset.
 571  *      Answer: if a packet caused RST, it is not for a socket
 572  *              existing in our system, if it is matched to a socket,
 573  *              it is just duplicate segment or bug in other side's TCP.
 574  *              So that we build reply only basing on parameters
 575  *              arrived with segment.
 576  *      Exception: precedence violation. We do not implement it in any case.
 577  */
 578
 579 static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
 580 {
 581         const struct tcphdr *th = tcp_hdr(skb);
 582         struct {
 583                 struct tcphdr th;
 584 #ifdef CONFIG_TCP_MD5SIG
 585                 __be32 opt[(TCPOLEN_MD5SIG_ALIGNED >> 2)];
 586 #endif
 587         } rep;
 588         struct ip_reply_arg arg;
 589 #ifdef CONFIG_TCP_MD5SIG
 590         struct tcp_md5sig_key *key;
 591         const __u8 *hash_location = NULL;
 592         unsigned char newhash[16];
 593         int genhash;
 594         struct sock *sk1 = NULL;
 595 #endif
 596         struct net *net;
 597
 598         /* Never send a reset in response to a reset. */
 599         if (th->rst)
 600                 return;
 601
 602         /* If sk not NULL, it means we did a successful lookup and incoming
 603          * route had to be correct. prequeue might have dropped our dst.
 604          */
 605         if (!sk && skb_rtable(skb)->rt_type != RTN_LOCAL)
 606                 return;
 607
 608         /* Swap the send and the receive. */
 609         memset(&rep, 0, sizeof(rep));
 610         rep.th.dest   = th->source;
 611         rep.th.source = th->dest;
 612         rep.th.doff   = sizeof(struct tcphdr) / 4;
 613         rep.th.rst    = 1;
 614
 615         if (th->ack) {
 616                 rep.th.seq = th->ack_seq;
 617         } else {
 618                 rep.th.ack = 1;
 619                 rep.th.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin +
 620                                        skb->len - (th->doff << 2));
 621         }
 622
 623         memset(&arg, 0, sizeof(arg));
 624         arg.iov[0].iov_base = (unsigned char *)&rep;
 625         arg.iov[0].iov_len  = sizeof(rep.th);
 626
 627         net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
 628 #ifdef CONFIG_TCP_MD5SIG
 629         hash_location = tcp_parse_md5sig_option(th);
 630         if (!sk && hash_location) {
 631                 /*
 632                  * active side is lost. Try to find listening socket through
 633                  * source port, and then find md5 key through listening socket.
 634                  * we are not loose security here:
 635                  * Incoming packet is checked with md5 hash with finding key,
 636                  * no RST generated if md5 hash doesn't match.
 637                  */
 638                 sk1 = __inet_lookup_listener(net,
 639                                              &tcp_hashinfo, ip_hdr(skb)->saddr,
 640                                              th->source, ip_hdr(skb)->daddr,
 641                                              ntohs(th->source), inet_iif(skb));
 642                 /* don't send rst if it can't find key */
 643                 if (!sk1)
 644                         return;
 645                 rcu_read_lock();
 646                 key = tcp_md5_do_lookup(sk1, (union tcp_md5_addr *)
 647                                         &ip_hdr(skb)->saddr, AF_INET);
 648                 if (!key)
 649                         goto release_sk1;
 650
 651                 genhash = tcp_v4_md5_hash_skb(newhash, key, NULL, skb);
 652                 if (genhash || memcmp(hash_location, newhash, 16) != 0)
 653                         goto release_sk1;
 654         } else {
 655                 key = sk ? tcp_md5_do_lookup(sk, (union tcp_md5_addr *)
 656                                              &ip_hdr(skb)->saddr,
 657                                              AF_INET) : NULL;
 658         }
 659
 660         if (key) {
 661                 rep.opt[0] = htonl((TCPOPT_NOP << 24) |
 662                                    (TCPOPT_NOP << 16) |
 663                                    (TCPOPT_MD5SIG << 8) |
 664                                    TCPOLEN_MD5SIG);
 665                 /* Update length and the length the header thinks exists */
 666                 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
 667                 rep.th.doff = arg.iov[0].iov_len / 4;
 668
 669                 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[1],
 670                                      key, ip_hdr(skb)->saddr,
 671                                      ip_hdr(skb)->daddr, &rep.th);
 672         }
 673 #endif
 674         arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
 675                                       ip_hdr(skb)->saddr, /* XXX */
 676                                       arg.iov[0].iov_len, IPPROTO_TCP, 0);
 677         arg.csumoffset = offsetof(struct tcphdr, check) / 2;
 678         arg.flags = (sk && inet_sk(sk)->transparent) ? IP_REPLY_ARG_NOSRCCHECK : 0;
 679         /* When socket is gone, all binding information is lost.
 680          * routing might fail in this case. No choice here, if we choose to force
 681          * input interface, we will misroute in case of asymmetric route.
 682          */
 683         if (sk)
 684                 arg.bound_dev_if = sk->sk_bound_dev_if;
 685
 686         arg.tos = ip_hdr(skb)->tos;
 687         ip_send_unicast_reply(*this_cpu_ptr(net->ipv4.tcp_sk),
 688                               skb, &TCP_SKB_CB(skb)->header.h4.opt,
 689                               ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,
 690                               &arg, arg.iov[0].iov_len);
 691
 692         TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
 693         TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS);
 694
 695 #ifdef CONFIG_TCP_MD5SIG
 696 release_sk1:
 697         if (sk1) {
 698                 rcu_read_unlock();
 699                 sock_put(sk1);
 700         }
 701 #endif
 702 }
 703
 704 /* The code following below sending ACKs in SYN-RECV and TIME-WAIT states
 705    outside socket context is ugly, certainly. What can I do?
 706  */
 707
 708 static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
 709                             u32 win, u32 tsval, u32 tsecr, int oif,
 710                             struct tcp_md5sig_key *key,
 711                             int reply_flags, u8 tos)
 712 {
 713         const struct tcphdr *th = tcp_hdr(skb);
 714         struct {
 715                 struct tcphdr th;
 716                 __be32 opt[(TCPOLEN_TSTAMP_ALIGNED >> 2)
 717 #ifdef CONFIG_TCP_MD5SIG
 718                            + (TCPOLEN_MD5SIG_ALIGNED >> 2)
 719 #endif
 720                         ];
 721         } rep;
 722         struct ip_reply_arg arg;
 723         struct net *net = dev_net(skb_dst(skb)->dev);
 724
 725         memset(&rep.th, 0, sizeof(struct tcphdr));
 726         memset(&arg, 0, sizeof(arg));
 727
 728         arg.iov[0].iov_base = (unsigned char *)&rep;
 729         arg.iov[0].iov_len  = sizeof(rep.th);
 730         if (tsecr) {
 731                 rep.opt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
 732                                    (TCPOPT_TIMESTAMP << 8) |
 733                                    TCPOLEN_TIMESTAMP);
 734                 rep.opt[1] = htonl(tsval);
 735                 rep.opt[2] = htonl(tsecr);
 736                 arg.iov[0].iov_len += TCPOLEN_TSTAMP_ALIGNED;
 737         }
 738
 739         /* Swap the send and the receive. */
 740         rep.th.dest    = th->source;
 741         rep.th.source  = th->dest;
 742         rep.th.doff    = arg.iov[0].iov_len / 4;
 743         rep.th.seq     = htonl(seq);
 744         rep.th.ack_seq = htonl(ack);
 745         rep.th.ack     = 1;
 746         rep.th.window  = htons(win);
 747
 748 #ifdef CONFIG_TCP_MD5SIG
 749         if (key) {
 750                 int offset = (tsecr) ? 3 : 0;
 751
 752                 rep.opt[offset++] = htonl((TCPOPT_NOP << 24) |
 753                                           (TCPOPT_NOP << 16) |
 754                                           (TCPOPT_MD5SIG << 8) |
 755                                           TCPOLEN_MD5SIG);
 756                 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
 757                 rep.th.doff = arg.iov[0].iov_len/4;
 758
 759                 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[offset],
 760                                     key, ip_hdr(skb)->saddr,
 761                                     ip_hdr(skb)->daddr, &rep.th);
 762         }
 763 #endif
 764         arg.flags = reply_flags;
 765         arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
 766                                       ip_hdr(skb)->saddr, /* XXX */
 767                                       arg.iov[0].iov_len, IPPROTO_TCP, 0);
 768         arg.csumoffset = offsetof(struct tcphdr, check) / 2;
 769         if (oif)
 770                 arg.bound_dev_if = oif;
 771         arg.tos = tos;
 772         ip_send_unicast_reply(*this_cpu_ptr(net->ipv4.tcp_sk),
 773                               skb, &TCP_SKB_CB(skb)->header.h4.opt,
 774                               ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,
 775                               &arg, arg.iov[0].iov_len);
 776
 777         TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
 778 }
 779
 780 static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
 781 {
 782         struct inet_timewait_sock *tw = inet_twsk(sk);
 783         struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
 784
 785         tcp_v4_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
 786                         tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
 787                         tcp_time_stamp + tcptw->tw_ts_offset,
 788                         tcptw->tw_ts_recent,
 789                         tw->tw_bound_dev_if,
 790                         tcp_twsk_md5_key(tcptw),
 791                         tw->tw_transparent ? IP_REPLY_ARG_NOSRCCHECK : 0,
 792                         tw->tw_tos
 793                         );
 794
 795         inet_twsk_put(tw);
 796 }
 797
 798 static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
 799                                   struct request_sock *req)
 800 {
 801         /* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV
 802          * sk->sk_state == TCP_SYN_RECV -> for Fast Open.
 803          */
 804         tcp_v4_send_ack(skb, (sk->sk_state == TCP_LISTEN) ?
 805                         tcp_rsk(req)->snt_isn + 1 : tcp_sk(sk)->snd_nxt,
 806                         tcp_rsk(req)->rcv_nxt, req->rcv_wnd,
 807                         tcp_time_stamp,
 808                         req->ts_recent,
 809                         0,
 810                         tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&ip_hdr(skb)->daddr,
 811                                           AF_INET),
 812                         inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0,
 813                         ip_hdr(skb)->tos);
 814 }
 815
 816 /*
 817  *      Send a SYN-ACK after having received a SYN.
 818  *      This still operates on a request_sock only, not on a big
 819  *      socket.
 820  */
 821 static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst,
 822                               struct flowi *fl,
 823                               struct request_sock *req,
 824                               u16 queue_mapping,
 825                               struct tcp_fastopen_cookie *foc)
 826 {
 827         const struct inet_request_sock *ireq = inet_rsk(req);
 828         struct flowi4 fl4;
 829         int err = -1;
 830         struct sk_buff *skb;
 831
 832         /* First, grab a route. */
 833         if (!dst && (dst = inet_csk_route_req(sk, &fl4, req)) == NULL)
 834                 return -1;
 835
 836         skb = tcp_make_synack(sk, dst, req, foc);
 837
 838         if (skb) {
 839                 __tcp_v4_send_check(skb, ireq->ir_loc_addr, ireq->ir_rmt_addr);
 840
 841                 skb_set_queue_mapping(skb, queue_mapping);
 842                 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
 843                                             ireq->ir_rmt_addr,
 844                                             ireq->opt);
 845                 err = net_xmit_eval(err);
 846         }
 847
 848         return err;
 849 }
 850
 851 /*
 852  *      IPv4 request_sock destructor.
 853  */
 854 static void tcp_v4_reqsk_destructor(struct request_sock *req)
 855 {
 856         kfree(inet_rsk(req)->opt);
 857 }
 858
 859
 860 #ifdef CONFIG_TCP_MD5SIG
 861 /*
 862  * RFC2385 MD5 checksumming requires a mapping of
 863  * IP address->MD5 Key.
 864  * We need to maintain these in the sk structure.
 865  */
 866
 867 /* Find the Key structure for an address.  */
 868 struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
 869                                          const union tcp_md5_addr *addr,
 870                                          int family)
 871 {
 872         const struct tcp_sock *tp = tcp_sk(sk);
 873         struct tcp_md5sig_key *key;
 874         unsigned int size = sizeof(struct in_addr);
 875         const struct tcp_md5sig_info *md5sig;
 876
 877         /* caller either holds rcu_read_lock() or socket lock */
 878         md5sig = rcu_dereference_check(tp->md5sig_info,
 879                                        sock_owned_by_user(sk) ||
 880                                        lockdep_is_held(&sk->sk_lock.slock));
 881         if (!md5sig)
 882                 return NULL;
 883 #if IS_ENABLED(CONFIG_IPV6)
 884         if (family == AF_INET6)
 885                 size = sizeof(struct in6_addr);
 886 #endif
 887         hlist_for_each_entry_rcu(key, &md5sig->head, node) {
 888                 if (key->family != family)
 889                         continue;
 890                 if (!memcmp(&key->addr, addr, size))
 891                         return key;
 892         }
 893         return NULL;
 894 }
 895 EXPORT_SYMBOL(tcp_md5_do_lookup);
 896
 897 struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
 898                                          const struct sock *addr_sk)
 899 {
 900         const union tcp_md5_addr *addr;
 901
 902         addr = (const union tcp_md5_addr *)&addr_sk->sk_daddr;
 903         return tcp_md5_do_lookup(sk, addr, AF_INET);
 904 }
 905 EXPORT_SYMBOL(tcp_v4_md5_lookup);
 906
 907 /* This can be called on a newly created socket, from other files */
 908 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
 909                    int family, const u8 *newkey, u8 newkeylen, gfp_t gfp)
 910 {
 911         /* Add Key to the list */
 912         struct tcp_md5sig_key *key;
 913         struct tcp_sock *tp = tcp_sk(sk);
 914         struct tcp_md5sig_info *md5sig;
 915
 916         key = tcp_md5_do_lookup(sk, addr, family);
 917         if (key) {
 918                 /* Pre-existing entry - just update that one. */
 919                 memcpy(key->key, newkey, newkeylen);
 920                 key->keylen = newkeylen;
 921                 return 0;
 922         }
 923
 924         md5sig = rcu_dereference_protected(tp->md5sig_info,
 925                                            sock_owned_by_user(sk));
 926         if (!md5sig) {
 927                 md5sig = kmalloc(sizeof(*md5sig), gfp);
 928                 if (!md5sig)
 929                         return -ENOMEM;
 930
 931                 sk_nocaps_add(sk, NETIF_F_GSO_MASK);
 932                 INIT_HLIST_HEAD(&md5sig->head);
 933                 rcu_assign_pointer(tp->md5sig_info, md5sig);
 934         }
 935
 936         key = sock_kmalloc(sk, sizeof(*key), gfp);
 937         if (!key)
 938                 return -ENOMEM;
 939         if (!tcp_alloc_md5sig_pool()) {
 940                 sock_kfree_s(sk, key, sizeof(*key));
 941                 return -ENOMEM;
 942         }
 943
 944         memcpy(key->key, newkey, newkeylen);
 945         key->keylen = newkeylen;
 946         key->family = family;
 947         memcpy(&key->addr, addr,
 948                (family == AF_INET6) ? sizeof(struct in6_addr) :
 949                                       sizeof(struct in_addr));
 950         hlist_add_head_rcu(&key->node, &md5sig->head);
 951         return 0;
 952 }
 953 EXPORT_SYMBOL(tcp_md5_do_add);
 954
 955 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, int family)
 956 {
 957         struct tcp_md5sig_key *key;
 958
 959         key = tcp_md5_do_lookup(sk, addr, family);
 960         if (!key)
 961                 return -ENOENT;
 962         hlist_del_rcu(&key->node);
 963         atomic_sub(sizeof(*key), &sk->sk_omem_alloc);
 964         kfree_rcu(key, rcu);
 965         return 0;
 966 }
 967 EXPORT_SYMBOL(tcp_md5_do_del);
 968
 969 static void tcp_clear_md5_list(struct sock *sk)
 970 {
 971         struct tcp_sock *tp = tcp_sk(sk);
 972         struct tcp_md5sig_key *key;
 973         struct hlist_node *n;
 974         struct tcp_md5sig_info *md5sig;
 975
 976         md5sig = rcu_dereference_protected(tp->md5sig_info, 1);
 977
 978         hlist_for_each_entry_safe(key, n, &md5sig->head, node) {
 979                 hlist_del_rcu(&key->node);
 980                 atomic_sub(sizeof(*key), &sk->sk_omem_alloc);
 981                 kfree_rcu(key, rcu);
 982         }
 983 }
 984
 985 static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval,
 986                                  int optlen)
 987 {
 988         struct tcp_md5sig cmd;
 989         struct sockaddr_in *sin = (struct sockaddr_in *)&cmd.tcpm_addr;
 990
 991         if (optlen < sizeof(cmd))
 992                 return -EINVAL;
 993
 994         if (copy_from_user(&cmd, optval, sizeof(cmd)))
 995                 return -EFAULT;
 996
 997         if (sin->sin_family != AF_INET)
 998                 return -EINVAL;
 999
1000         if (!cmd.tcpm_keylen)
1001                 return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin->sin_addr.s_addr,
1002                                       AF_INET);
1003
1004         if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
1005                 return -EINVAL;
1006
1007         return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin->sin_addr.s_addr,
1008                               AF_INET, cmd.tcpm_key, cmd.tcpm_keylen,
1009                               GFP_KERNEL);
1010 }
1011
1012 static int tcp_v4_md5_hash_pseudoheader(struct tcp_md5sig_pool *hp,
1013                                         __be32 daddr, __be32 saddr, int nbytes)
1014 {
1015         struct tcp4_pseudohdr *bp;
1016         struct scatterlist sg;
1017
1018         bp = &hp->md5_blk.ip4;
1019
1020         /*
1021          * 1. the TCP pseudo-header (in the order: source IP address,
1022          * destination IP address, zero-padded protocol number, and
1023          * segment length)
1024          */
1025         bp->saddr = saddr;
1026         bp->daddr = daddr;
1027         bp->pad = 0;
1028         bp->protocol = IPPROTO_TCP;
1029         bp->len = cpu_to_be16(nbytes);
1030
1031         sg_init_one(&sg, bp, sizeof(*bp));
1032         return crypto_hash_update(&hp->md5_desc, &sg, sizeof(*bp));
1033 }
1034
1035 static int tcp_v4_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key,
1036                                __be32 daddr, __be32 saddr, const struct tcphdr *th)
1037 {
1038         struct tcp_md5sig_pool *hp;
1039         struct hash_desc *desc;
1040
1041         hp = tcp_get_md5sig_pool();
1042         if (!hp)
1043                 goto clear_hash_noput;
1044         desc = &hp->md5_desc;
1045
1046         if (crypto_hash_init(desc))
1047                 goto clear_hash;
1048         if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, th->doff << 2))
1049                 goto clear_hash;
1050         if (tcp_md5_hash_header(hp, th))
1051                 goto clear_hash;
1052         if (tcp_md5_hash_key(hp, key))
1053                 goto clear_hash;
1054         if (crypto_hash_final(desc, md5_hash))
1055                 goto clear_hash;
1056
1057         tcp_put_md5sig_pool();
1058         return 0;
1059
1060 clear_hash:
1061         tcp_put_md5sig_pool();
1062 clear_hash_noput:
1063         memset(md5_hash, 0, 16);
1064         return 1;
1065 }
1066
1067 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1068                         const struct sock *sk,
1069                         const struct sk_buff *skb)
1070 {
1071         struct tcp_md5sig_pool *hp;
1072         struct hash_desc *desc;
1073         const struct tcphdr *th = tcp_hdr(skb);
1074         __be32 saddr, daddr;
1075
1076         if (sk) { /* valid for establish/request sockets */
1077                 saddr = sk->sk_rcv_saddr;
1078                 daddr = sk->sk_daddr;
1079         } else {
1080                 const struct iphdr *iph = ip_hdr(skb);
1081                 saddr = iph->saddr;
1082                 daddr = iph->daddr;
1083         }
1084
1085         hp = tcp_get_md5sig_pool();
1086         if (!hp)
1087                 goto clear_hash_noput;
1088         desc = &hp->md5_desc;
1089
1090         if (crypto_hash_init(desc))
1091                 goto clear_hash;
1092
1093         if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, skb->len))
1094                 goto clear_hash;
1095         if (tcp_md5_hash_header(hp, th))
1096                 goto clear_hash;
1097         if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2))
1098                 goto clear_hash;
1099         if (tcp_md5_hash_key(hp, key))
1100                 goto clear_hash;
1101         if (crypto_hash_final(desc, md5_hash))
1102                 goto clear_hash;
1103
1104         tcp_put_md5sig_pool();
1105         return 0;
1106
1107 clear_hash:
1108         tcp_put_md5sig_pool();
1109 clear_hash_noput:
1110         memset(md5_hash, 0, 16);
1111         return 1;
1112 }
1113 EXPORT_SYMBOL(tcp_v4_md5_hash_skb);
1114
1115 /* Called with rcu_read_lock() */
1116 static bool tcp_v4_inbound_md5_hash(struct sock *sk,
1117                                     const struct sk_buff *skb)
1118 {
1119         /*
1120          * This gets called for each TCP segment that arrives
1121          * so we want to be efficient.
1122          * We have 3 drop cases:
1123          * o No MD5 hash and one expected.
1124          * o MD5 hash and we're not expecting one.
1125          * o MD5 hash and its wrong.
1126          */
1127         const __u8 *hash_location = NULL;
1128         struct tcp_md5sig_key *hash_expected;
1129         const struct iphdr *iph = ip_hdr(skb);
1130         const struct tcphdr *th = tcp_hdr(skb);
1131         int genhash;
1132         unsigned char newhash[16];
1133
1134         hash_expected = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&iph->saddr,
1135                                           AF_INET);
1136         hash_location = tcp_parse_md5sig_option(th);
1137
1138         /* We've parsed the options - do we have a hash? */
1139         if (!hash_expected && !hash_location)
1140                 return false;
1141
1142         if (hash_expected && !hash_location) {
1143                 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
1144                 return true;
1145         }
1146
1147         if (!hash_expected && hash_location) {
1148                 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
1149                 return true;
1150         }
1151
1152         /* Okay, so this is hash_expected and hash_location -
1153          * so we need to calculate the checksum.
1154          */
1155         genhash = tcp_v4_md5_hash_skb(newhash,
1156                                       hash_expected,
1157                                       NULL, skb);
1158
1159         if (genhash || memcmp(hash_location, newhash, 16) != 0) {
1160                 net_info_ratelimited("MD5 Hash failed for (%pI4, %d)->(%pI4, %d)%s\n",
1161                                      &iph->saddr, ntohs(th->source),
1162                                      &iph->daddr, ntohs(th->dest),
1163                                      genhash ? " tcp_v4_calc_md5_hash failed"
1164                                      : "");
1165                 return true;
1166         }
1167         return false;
1168 }
1169 #endif
1170
1171 static void tcp_v4_init_req(struct request_sock *req, struct sock *sk_listener,
1172                             struct sk_buff *skb)
1173 {
1174         struct inet_request_sock *ireq = inet_rsk(req);
1175
1176         sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr);
1177         sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr);
1178         ireq->no_srccheck = inet_sk(sk_listener)->transparent;
1179         ireq->opt = tcp_v4_save_options(skb);
1180 }
1181
1182 static struct dst_entry *tcp_v4_route_req(struct sock *sk, struct flowi *fl,
1183                                           const struct request_sock *req,
1184                                           bool *strict)
1185 {
1186         struct dst_entry *dst = inet_csk_route_req(sk, &fl->u.ip4, req);
1187
1188         if (strict) {
1189                 if (fl->u.ip4.daddr == inet_rsk(req)->ir_rmt_addr)
1190                         *strict = true;
1191                 else
1192                         *strict = false;
1193         }
1194
1195         return dst;
1196 }
1197
1198 struct request_sock_ops tcp_request_sock_ops __read_mostly = {
1199         .family         =       PF_INET,
1200         .obj_size       =       sizeof(struct tcp_request_sock),
1201         .rtx_syn_ack    =       tcp_rtx_synack,
1202         .send_ack       =       tcp_v4_reqsk_send_ack,
1203         .destructor     =       tcp_v4_reqsk_destructor,
1204         .send_reset     =       tcp_v4_send_reset,
1205         .syn_ack_timeout =      tcp_syn_ack_timeout,
1206 };
1207
1208 static const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
1209         .mss_clamp      =       TCP_MSS_DEFAULT,
1210 #ifdef CONFIG_TCP_MD5SIG
1211         .req_md5_lookup =       tcp_v4_md5_lookup,
1212         .calc_md5_hash  =       tcp_v4_md5_hash_skb,
1213 #endif
1214         .init_req       =       tcp_v4_init_req,
1215 #ifdef CONFIG_SYN_COOKIES
1216         .cookie_init_seq =      cookie_v4_init_sequence,
1217 #endif
1218         .route_req      =       tcp_v4_route_req,
1219         .init_seq       =       tcp_v4_init_sequence,
1220         .send_synack    =       tcp_v4_send_synack,
1221         .queue_hash_add =       inet_csk_reqsk_queue_hash_add,
1222 };
1223
1224 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
1225 {
1226         /* Never answer to SYNs send to broadcast or multicast */
1227         if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
1228                 goto drop;
1229
1230         return tcp_conn_request(&tcp_request_sock_ops,
1231                                 &tcp_request_sock_ipv4_ops, sk, skb);
1232
1233 drop:
1234         NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
1235         return 0;
1236 }
1237 EXPORT_SYMBOL(tcp_v4_conn_request);
1238
1239
1240 /*
1241  * The three way handshake has completed - we got a valid synack -
1242  * now create the new socket.
1243  */
1244 struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
1245                                   struct request_sock *req,
1246                                   struct dst_entry *dst)
1247 {
1248         struct inet_request_sock *ireq;
1249         struct inet_sock *newinet;
1250         struct tcp_sock *newtp;
1251         struct sock *newsk;
1252 #ifdef CONFIG_TCP_MD5SIG
1253         struct tcp_md5sig_key *key;
1254 #endif
1255         struct ip_options_rcu *inet_opt;
1256
1257         if (sk_acceptq_is_full(sk))
1258                 goto exit_overflow;
1259
1260         newsk = tcp_create_openreq_child(sk, req, skb);
1261         if (!newsk)
1262                 goto exit_nonewsk;
1263
1264         newsk->sk_gso_type = SKB_GSO_TCPV4;
1265         inet_sk_rx_dst_set(newsk, skb);
1266
1267         newtp                 = tcp_sk(newsk);
1268         newinet               = inet_sk(newsk);
1269         ireq                  = inet_rsk(req);
1270         sk_daddr_set(newsk, ireq->ir_rmt_addr);
1271         sk_rcv_saddr_set(newsk, ireq->ir_loc_addr);
1272         newinet->inet_saddr           = ireq->ir_loc_addr;
1273         inet_opt              = ireq->opt;
1274         rcu_assign_pointer(newinet->inet_opt, inet_opt);
1275         ireq->opt             = NULL;
1276         newinet->mc_index     = inet_iif(skb);
1277         newinet->mc_ttl       = ip_hdr(skb)->ttl;
1278         newinet->rcv_tos      = ip_hdr(skb)->tos;
1279         inet_csk(newsk)->icsk_ext_hdr_len = 0;
1280         inet_set_txhash(newsk);
1281         if (inet_opt)
1282                 inet_csk(newsk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
1283         newinet->inet_id = newtp->write_seq ^ jiffies;
1284
1285         if (!dst) {
1286                 dst = inet_csk_route_child_sock(sk, newsk, req);
1287                 if (!dst)
1288                         goto put_and_exit;
1289         } else {
1290                 /* syncookie case : see end of cookie_v4_check() */
1291         }
1292         sk_setup_caps(newsk, dst);
1293
1294         tcp_ca_openreq_child(newsk, dst);
1295
1296         tcp_sync_mss(newsk, dst_mtu(dst));
1297         newtp->advmss = dst_metric_advmss(dst);
1298         if (tcp_sk(sk)->rx_opt.user_mss &&
1299             tcp_sk(sk)->rx_opt.user_mss < newtp->advmss)
1300                 newtp->advmss = tcp_sk(sk)->rx_opt.user_mss;
1301
1302         tcp_initialize_rcv_mss(newsk);
1303
1304 #ifdef CONFIG_TCP_MD5SIG
1305         /* Copy over the MD5 key from the original socket */
1306         key = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&newinet->inet_daddr,
1307                                 AF_INET);
1308         if (key) {
1309                 /*
1310                  * We're using one, so create a matching key
1311                  * on the newsk structure. If we fail to get
1312                  * memory, then we end up not copying the key
1313                  * across. Shucks.
1314                  */
1315                 tcp_md5_do_add(newsk, (union tcp_md5_addr *)&newinet->inet_daddr,
1316                                AF_INET, key->key, key->keylen, GFP_ATOMIC);
1317                 sk_nocaps_add(newsk, NETIF_F_GSO_MASK);
1318         }
1319 #endif
1320
1321         if (__inet_inherit_port(sk, newsk) < 0)
1322                 goto put_and_exit;
1323         __inet_hash_nolisten(newsk, NULL);
1324
1325         return newsk;
1326
1327 exit_overflow:
1328         NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
1329 exit_nonewsk:
1330         dst_release(dst);
1331 exit:
1332         NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
1333         return NULL;
1334 put_and_exit:
1335         inet_csk_prepare_forced_close(newsk);
1336         tcp_done(newsk);
1337         goto exit;
1338 }
1339 EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
1340
1341 static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
1342 {
1343         const struct tcphdr *th = tcp_hdr(skb);
1344         const struct iphdr *iph = ip_hdr(skb);
1345         struct request_sock *req;
1346         struct sock *nsk;
1347
1348         req = inet_csk_search_req(sk, th->source, iph->saddr, iph->daddr);
1349         if (req) {
1350                 nsk = tcp_check_req(sk, skb, req, false);
1351                 reqsk_put(req);
1352                 return nsk;
1353         }
1354
1355         nsk = inet_lookup_established(sock_net(sk), &tcp_hashinfo, iph->saddr,
1356                         th->source, iph->daddr, th->dest, inet_iif(skb));
1357
1358         if (nsk) {
1359                 if (nsk->sk_state != TCP_TIME_WAIT) {
1360                         bh_lock_sock(nsk);
1361                         return nsk;
1362                 }
1363                 inet_twsk_put(inet_twsk(nsk));
1364                 return NULL;
1365         }
1366
1367 #ifdef CONFIG_SYN_COOKIES
1368         if (!th->syn)
1369                 sk = cookie_v4_check(sk, skb);
1370 #endif
1371         return sk;
1372 }
1373
1374 /* The socket must have it's spinlock held when we get
1375  * here.
1376  *
1377  * We have a potential double-lock case here, so even when
1378  * doing backlog processing we use the BH locking scheme.
1379  * This is because we cannot sleep with the original spinlock
1380  * held.
1381  */
1382 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
1383 {
1384         struct sock *rsk;
1385
1386         if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
1387                 struct dst_entry *dst = sk->sk_rx_dst;
1388
1389                 sock_rps_save_rxhash(sk, skb);
1390                 sk_mark_napi_id(sk, skb);
1391                 if (dst) {
1392                         if (inet_sk(sk)->rx_dst_ifindex != skb->skb_iif ||
1393                             !dst->ops->check(dst, 0)) {
1394                                 dst_release(dst);
1395                                 sk->sk_rx_dst = NULL;
1396                         }
1397                 }
1398                 tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len);
1399                 return 0;
1400         }
1401
1402         if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb))
1403                 goto csum_err;
1404
1405         if (sk->sk_state == TCP_LISTEN) {
1406                 struct sock *nsk = tcp_v4_hnd_req(sk, skb);
1407                 if (!nsk)
1408                         goto discard;
1409
1410                 if (nsk != sk) {
1411                         sock_rps_save_rxhash(nsk, skb);
1412                         sk_mark_napi_id(sk, skb);
1413                         if (tcp_child_process(sk, nsk, skb)) {
1414                                 rsk = nsk;
1415                                 goto reset;
1416                         }
1417                         return 0;
1418                 }
1419         } else
1420                 sock_rps_save_rxhash(sk, skb);
1421
1422         if (tcp_rcv_state_process(sk, skb, tcp_hdr(skb), skb->len)) {
1423                 rsk = sk;
1424                 goto reset;
1425         }
1426         return 0;
1427
1428 reset:
1429         tcp_v4_send_reset(rsk, skb);
1430 discard:
1431         kfree_skb(skb);
1432         /* Be careful here. If this function gets more complicated and
1433          * gcc suffers from register pressure on the x86, sk (in %ebx)
1434          * might be destroyed here. This current version compiles correctly,
1435          * but you have been warned.
1436          */
1437         return 0;
1438
1439 csum_err:
1440         TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_CSUMERRORS);
1441         TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
1442         goto discard;
1443 }
1444 EXPORT_SYMBOL(tcp_v4_do_rcv);
1445
1446 void tcp_v4_early_demux(struct sk_buff *skb)
1447 {
1448         const struct iphdr *iph;
1449         const struct tcphdr *th;
1450         struct sock *sk;
1451
1452         if (skb->pkt_type != PACKET_HOST)
1453                 return;
1454
1455         if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct tcphdr)))
1456                 return;
1457
1458         iph = ip_hdr(skb);
1459         th = tcp_hdr(skb);
1460
1461         if (th->doff < sizeof(struct tcphdr) / 4)
1462                 return;
1463
1464         sk = __inet_lookup_established(dev_net(skb->dev), &tcp_hashinfo,
1465                                        iph->saddr, th->source,
1466                                        iph->daddr, ntohs(th->dest),
1467                                        skb->skb_iif);
1468         if (sk) {
1469                 skb->sk = sk;
1470                 skb->destructor = sock_edemux;
1471                 if (sk_fullsock(sk)) {
1472                         struct dst_entry *dst = READ_ONCE(sk->sk_rx_dst);
1473
1474                         if (dst)
1475                                 dst = dst_check(dst, 0);
1476                         if (dst &&
1477                             inet_sk(sk)->rx_dst_ifindex == skb->skb_iif)
1478                                 skb_dst_set_noref(skb, dst);
1479                 }
1480         }
1481 }
1482
1483 /* Packet is added to VJ-style prequeue for processing in process
1484  * context, if a reader task is waiting. Apparently, this exciting
1485  * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
1486  * failed somewhere. Latency? Burstiness? Well, at least now we will
1487  * see, why it failed. 8)8)                               --ANK
1488  *
1489  */
1490 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb)
1491 {
1492         struct tcp_sock *tp = tcp_sk(sk);
1493
1494         if (sysctl_tcp_low_latency || !tp->ucopy.task)
1495                 return false;
1496
1497         if (skb->len <= tcp_hdrlen(skb) &&
1498             skb_queue_len(&tp->ucopy.prequeue) == 0)
1499                 return false;
1500
1501         /* Before escaping RCU protected region, we need to take care of skb
1502          * dst. Prequeue is only enabled for established sockets.
1503          * For such sockets, we might need the skb dst only to set sk->sk_rx_dst
1504          * Instead of doing full sk_rx_dst validity here, let's perform
1505          * an optimistic check.
1506          */
1507         if (likely(sk->sk_rx_dst))
1508                 skb_dst_drop(skb);
1509         else
1510                 skb_dst_force(skb);
1511
1512         __skb_queue_tail(&tp->ucopy.prequeue, skb);
1513         tp->ucopy.memory += skb->truesize;
1514         if (tp->ucopy.memory > sk->sk_rcvbuf) {
1515                 struct sk_buff *skb1;
1516
1517                 BUG_ON(sock_owned_by_user(sk));
1518
1519                 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
1520                         sk_backlog_rcv(sk, skb1);
1521                         NET_INC_STATS_BH(sock_net(sk),
1522                                          LINUX_MIB_TCPPREQUEUEDROPPED);
1523                 }
1524
1525                 tp->ucopy.memory = 0;
1526         } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
1527                 wake_up_interruptible_sync_poll(sk_sleep(sk),
1528                                            POLLIN | POLLRDNORM | POLLRDBAND);
1529                 if (!inet_csk_ack_scheduled(sk))
1530                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
1531                                                   (3 * tcp_rto_min(sk)) / 4,
1532                                                   TCP_RTO_MAX);
1533         }
1534         return true;
1535 }
1536 EXPORT_SYMBOL(tcp_prequeue);
1537
1538 /*
1539  *      From tcp_input.c
1540  */
1541
1542 int tcp_v4_rcv(struct sk_buff *skb)
1543 {
1544         const struct iphdr *iph;
1545         const struct tcphdr *th;
1546         struct sock *sk;
1547         int ret;
1548         struct net *net = dev_net(skb->dev);
1549
1550         if (skb->pkt_type != PACKET_HOST)
1551                 goto discard_it;
1552
1553         /* Count it even if it's bad */
1554         TCP_INC_STATS_BH(net, TCP_MIB_INSEGS);
1555
1556         if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
1557                 goto discard_it;
1558
1559         th = tcp_hdr(skb);
1560
1561         if (th->doff < sizeof(struct tcphdr) / 4)
1562                 goto bad_packet;
1563         if (!pskb_may_pull(skb, th->doff * 4))
1564                 goto discard_it;
1565
1566         /* An explanation is required here, I think.
1567          * Packet length and doff are validated by header prediction,
1568          * provided case of th->doff==0 is eliminated.
1569          * So, we defer the checks. */
1570
1571         if (skb_checksum_init(skb, IPPROTO_TCP, inet_compute_pseudo))
1572                 goto csum_error;
1573
1574         th = tcp_hdr(skb);
1575         iph = ip_hdr(skb);
1576         /* This is tricky : We move IPCB at its correct location into TCP_SKB_CB()
1577          * barrier() makes sure compiler wont play fool^Waliasing games.
1578          */
1579         memmove(&TCP_SKB_CB(skb)->header.h4, IPCB(skb),
1580                 sizeof(struct inet_skb_parm));
1581         barrier();
1582
1583         TCP_SKB_CB(skb)->seq = ntohl(th->seq);
1584         TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
1585                                     skb->len - th->doff * 4);
1586         TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
1587         TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th);
1588         TCP_SKB_CB(skb)->tcp_tw_isn = 0;
1589         TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph);
1590         TCP_SKB_CB(skb)->sacked  = 0;
1591
1592         sk = __inet_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest);
1593         if (!sk)
1594                 goto no_tcp_socket;
1595
1596 process:
1597         if (sk->sk_state == TCP_TIME_WAIT)
1598                 goto do_time_wait;
1599
1600         if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) {
1601                 NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
1602                 goto discard_and_relse;
1603         }
1604
1605         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
1606                 goto discard_and_relse;
1607
1608 #ifdef CONFIG_TCP_MD5SIG
1609         /*
1610          * We really want to reject the packet as early as possible
1611          * if:
1612          *  o We're expecting an MD5'd packet and this is no MD5 tcp option
1613          *  o There is an MD5 option and we're not expecting one
1614          */
1615         if (tcp_v4_inbound_md5_hash(sk, skb))
1616                 goto discard_and_relse;
1617 #endif
1618
1619         nf_reset(skb);
1620
1621         if (sk_filter(sk, skb))
1622                 goto discard_and_relse;
1623
1624         sk_incoming_cpu_update(sk);
1625         skb->dev = NULL;
1626
1627         bh_lock_sock_nested(sk);
1628         ret = 0;
1629         if (!sock_owned_by_user(sk)) {
1630                 if (!tcp_prequeue(sk, skb))
1631                         ret = tcp_v4_do_rcv(sk, skb);
1632         } else if (unlikely(sk_add_backlog(sk, skb,
1633                                            sk->sk_rcvbuf + sk->sk_sndbuf))) {
1634                 bh_unlock_sock(sk);
1635                 NET_INC_STATS_BH(net, LINUX_MIB_TCPBACKLOGDROP);
1636                 goto discard_and_relse;
1637         }
1638         bh_unlock_sock(sk);
1639
1640         sock_put(sk);
1641
1642         return ret;
1643
1644 no_tcp_socket:
1645         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
1646                 goto discard_it;
1647
1648         if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1649 csum_error:
1650                 TCP_INC_STATS_BH(net, TCP_MIB_CSUMERRORS);
1651 bad_packet:
1652                 TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
1653         } else {
1654                 tcp_v4_send_reset(NULL, skb);
1655         }
1656
1657 discard_it:
1658         /* Discard frame. */
1659         kfree_skb(skb);
1660         return 0;
1661
1662 discard_and_relse:
1663         sock_put(sk);
1664         goto discard_it;
1665
1666 do_time_wait:
1667         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1668                 inet_twsk_put(inet_twsk(sk));
1669                 goto discard_it;
1670         }
1671
1672         if (skb->len < (th->doff << 2)) {
1673                 inet_twsk_put(inet_twsk(sk));
1674                 goto bad_packet;
1675         }
1676         if (tcp_checksum_complete(skb)) {
1677                 inet_twsk_put(inet_twsk(sk));
1678                 goto csum_error;
1679         }
1680         switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
1681         case TCP_TW_SYN: {
1682                 struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev),
1683                                                         &tcp_hashinfo,
1684                                                         iph->saddr, th->source,
1685                                                         iph->daddr, th->dest,
1686                                                         inet_iif(skb));
1687                 if (sk2) {
1688                         inet_twsk_deschedule(inet_twsk(sk));
1689                         inet_twsk_put(inet_twsk(sk));
1690                         sk = sk2;
1691                         goto process;
1692                 }
1693                 /* Fall through to ACK */
1694         }
1695         case TCP_TW_ACK:
1696                 tcp_v4_timewait_ack(sk, skb);
1697                 break;
1698         case TCP_TW_RST:
1699                 goto no_tcp_socket;
1700         case TCP_TW_SUCCESS:;
1701         }
1702         goto discard_it;
1703 }
1704
1705 static struct timewait_sock_ops tcp_timewait_sock_ops = {
1706         .twsk_obj_size  = sizeof(struct tcp_timewait_sock),
1707         .twsk_unique    = tcp_twsk_unique,
1708         .twsk_destructor= tcp_twsk_destructor,
1709 };
1710
1711 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
1712 {
1713         struct dst_entry *dst = skb_dst(skb);
1714
1715         if (dst) {
1716                 dst_hold(dst);
1717                 sk->sk_rx_dst = dst;
1718                 inet_sk(sk)->rx_dst_ifindex = skb->skb_iif;
1719         }
1720 }
1721 EXPORT_SYMBOL(inet_sk_rx_dst_set);
1722
1723 const struct inet_connection_sock_af_ops ipv4_specific = {
1724         .queue_xmit        = ip_queue_xmit,
1725         .send_check        = tcp_v4_send_check,
1726         .rebuild_header    = inet_sk_rebuild_header,
1727         .sk_rx_dst_set     = inet_sk_rx_dst_set,
1728         .conn_request      = tcp_v4_conn_request,
1729         .syn_recv_sock     = tcp_v4_syn_recv_sock,
1730         .net_header_len    = sizeof(struct iphdr),
1731         .setsockopt        = ip_setsockopt,
1732         .getsockopt        = ip_getsockopt,
1733         .addr2sockaddr     = inet_csk_addr2sockaddr,
1734         .sockaddr_len      = sizeof(struct sockaddr_in),
1735         .bind_conflict     = inet_csk_bind_conflict,
1736 #ifdef CONFIG_COMPAT
1737         .compat_setsockopt = compat_ip_setsockopt,
1738         .compat_getsockopt = compat_ip_getsockopt,
1739 #endif
1740         .mtu_reduced       = tcp_v4_mtu_reduced,
1741 };
1742 EXPORT_SYMBOL(ipv4_specific);
1743
1744 #ifdef CONFIG_TCP_MD5SIG
1745 static const struct tcp_sock_af_ops tcp_sock_ipv4_specific = {
1746         .md5_lookup             = tcp_v4_md5_lookup,
1747         .calc_md5_hash          = tcp_v4_md5_hash_skb,
1748         .md5_parse              = tcp_v4_parse_md5_keys,
1749 };
1750 #endif
1751
1752 /* NOTE: A lot of things set to zero explicitly by call to
1753  *       sk_alloc() so need not be done here.
1754  */
1755 static int tcp_v4_init_sock(struct sock *sk)
1756 {
1757         struct inet_connection_sock *icsk = inet_csk(sk);
1758
1759         tcp_init_sock(sk);
1760
1761         icsk->icsk_af_ops = &ipv4_specific;
1762
1763 #ifdef CONFIG_TCP_MD5SIG
1764         tcp_sk(sk)->af_specific = &tcp_sock_ipv4_specific;
1765 #endif
1766
1767         return 0;
1768 }
1769
1770 void tcp_v4_destroy_sock(struct sock *sk)
1771 {
1772         struct tcp_sock *tp = tcp_sk(sk);
1773
1774         tcp_clear_xmit_timers(sk);
1775
1776         tcp_cleanup_congestion_control(sk);
1777
1778         /* Cleanup up the write buffer. */
1779         tcp_write_queue_purge(sk);
1780
1781         /* Cleans up our, hopefully empty, out_of_order_queue. */
1782         __skb_queue_purge(&tp->out_of_order_queue);
1783
1784 #ifdef CONFIG_TCP_MD5SIG
1785         /* Clean up the MD5 key list, if any */
1786         if (tp->md5sig_info) {
1787                 tcp_clear_md5_list(sk);
1788                 kfree_rcu(tp->md5sig_info, rcu);
1789                 tp->md5sig_info = NULL;
1790         }
1791 #endif
1792
1793         /* Clean prequeue, it must be empty really */
1794         __skb_queue_purge(&tp->ucopy.prequeue);
1795
1796         /* Clean up a referenced TCP bind bucket. */
1797         if (inet_csk(sk)->icsk_bind_hash)
1798                 inet_put_port(sk);
1799
1800         BUG_ON(tp->fastopen_rsk);
1801
1802         /* If socket is aborted during connect operation */
1803         tcp_free_fastopen_req(tp);
1804
1805         sk_sockets_allocated_dec(sk);
1806         sock_release_memcg(sk);
1807 }
1808 EXPORT_SYMBOL(tcp_v4_destroy_sock);
1809
1810 #ifdef CONFIG_PROC_FS
1811 /* Proc filesystem TCP sock list dumping. */
1812
1813 /*
1814  * Get next listener socket follow cur.  If cur is NULL, get first socket
1815  * starting from bucket given in st->bucket; when st->bucket is zero the
1816  * very first socket in the hash table is returned.
1817  */
1818 static void *listening_get_next(struct seq_file *seq, void *cur)
1819 {
1820         struct inet_connection_sock *icsk;
1821         struct hlist_nulls_node *node;
1822         struct sock *sk = cur;
1823         struct inet_listen_hashbucket *ilb;
1824         struct tcp_iter_state *st = seq->private;
1825         struct net *net = seq_file_net(seq);
1826
1827         if (!sk) {
1828                 ilb = &tcp_hashinfo.listening_hash[st->bucket];
1829                 spin_lock_bh(&ilb->lock);
1830                 sk = sk_nulls_head(&ilb->head);
1831                 st->offset = 0;
1832                 goto get_sk;
1833         }
1834         ilb = &tcp_hashinfo.listening_hash[st->bucket];
1835         ++st->num;
1836         ++st->offset;
1837
1838         if (st->state == TCP_SEQ_STATE_OPENREQ) {
1839                 struct request_sock *req = cur;
1840
1841                 icsk = inet_csk(st->syn_wait_sk);
1842                 req = req->dl_next;
1843                 while (1) {
1844                         while (req) {
1845                                 if (req->rsk_ops->family == st->family) {
1846                                         cur = req;
1847                                         goto out;
1848                                 }
1849                                 req = req->dl_next;
1850                         }
1851                         if (++st->sbucket >= icsk->icsk_accept_queue.listen_opt->nr_table_entries)
1852                                 break;
1853 get_req:
1854                         req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];
1855                 }
1856                 sk        = sk_nulls_next(st->syn_wait_sk);
1857                 st->state = TCP_SEQ_STATE_LISTENING;
1858                 spin_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1859         } else {
1860                 icsk = inet_csk(sk);
1861                 spin_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1862                 if (reqsk_queue_len(&icsk->icsk_accept_queue))
1863                         goto start_req;
1864                 spin_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1865                 sk = sk_nulls_next(sk);
1866         }
1867 get_sk:
1868         sk_nulls_for_each_from(sk, node) {
1869                 if (!net_eq(sock_net(sk), net))
1870                         continue;
1871                 if (sk->sk_family == st->family) {
1872                         cur = sk;
1873                         goto out;
1874                 }
1875                 icsk = inet_csk(sk);
1876                 spin_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1877                 if (reqsk_queue_len(&icsk->icsk_accept_queue)) {
1878 start_req:
1879                         st->uid         = sock_i_uid(sk);
1880                         st->syn_wait_sk = sk;
1881                         st->state       = TCP_SEQ_STATE_OPENREQ;
1882                         st->sbucket     = 0;
1883                         goto get_req;
1884                 }
1885                 spin_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1886         }
1887         spin_unlock_bh(&ilb->lock);
1888         st->offset = 0;
1889         if (++st->bucket < INET_LHTABLE_SIZE) {
1890                 ilb = &tcp_hashinfo.listening_hash[st->bucket];
1891                 spin_lock_bh(&ilb->lock);
1892                 sk = sk_nulls_head(&ilb->head);
1893                 goto get_sk;
1894         }
1895         cur = NULL;
1896 out:
1897         return cur;
1898 }
1899
1900 static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
1901 {
1902         struct tcp_iter_state *st = seq->private;
1903         void *rc;
1904
1905         st->bucket = 0;
1906         st->offset = 0;
1907         rc = listening_get_next(seq, NULL);
1908
1909         while (rc && *pos) {
1910                 rc = listening_get_next(seq, rc);
1911                 --*pos;
1912         }
1913         return rc;
1914 }
1915
1916 static inline bool empty_bucket(const struct tcp_iter_state *st)
1917 {
1918         return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain);
1919 }
1920
1921 /*
1922  * Get first established socket starting from bucket given in st->bucket.
1923  * If st->bucket is zero, the very first socket in the hash is returned.
1924  */
1925 static void *established_get_first(struct seq_file *seq)
1926 {
1927         struct tcp_iter_state *st = seq->private;
1928         struct net *net = seq_file_net(seq);
1929         void *rc = NULL;
1930
1931         st->offset = 0;
1932         for (; st->bucket <= tcp_hashinfo.ehash_mask; ++st->bucket) {
1933                 struct sock *sk;
1934                 struct hlist_nulls_node *node;
1935                 spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
1936
1937                 /* Lockless fast path for the common case of empty buckets */
1938                 if (empty_bucket(st))
1939                         continue;
1940
1941                 spin_lock_bh(lock);
1942                 sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
1943                         if (sk->sk_family != st->family ||
1944                             !net_eq(sock_net(sk), net)) {
1945                                 continue;
1946                         }
1947                         rc = sk;
1948                         goto out;
1949                 }
1950                 spin_unlock_bh(lock);
1951         }
1952 out:
1953         return rc;
1954 }
1955
1956 static void *established_get_next(struct seq_file *seq, void *cur)
1957 {
1958         struct sock *sk = cur;
1959         struct hlist_nulls_node *node;
1960         struct tcp_iter_state *st = seq->private;
1961         struct net *net = seq_file_net(seq);
1962
1963         ++st->num;
1964         ++st->offset;
1965
1966         sk = sk_nulls_next(sk);
1967
1968         sk_nulls_for_each_from(sk, node) {
1969                 if (sk->sk_family == st->family && net_eq(sock_net(sk), net))
1970                         return sk;
1971         }
1972
1973         spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
1974         ++st->bucket;
1975         return established_get_first(seq);
1976 }
1977
1978 static void *established_get_idx(struct seq_file *seq, loff_t pos)
1979 {
1980         struct tcp_iter_state *st = seq->private;
1981         void *rc;
1982
1983         st->bucket = 0;
1984         rc = established_get_first(seq);
1985
1986         while (rc && pos) {
1987                 rc = established_get_next(seq, rc);
1988                 --pos;
1989         }
1990         return rc;
1991 }
1992
1993 static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
1994 {
1995         void *rc;
1996         struct tcp_iter_state *st = seq->private;
1997
1998         st->state = TCP_SEQ_STATE_LISTENING;
1999         rc        = listening_get_idx(seq, &pos);
2000
2001         if (!rc) {
2002                 st->state = TCP_SEQ_STATE_ESTABLISHED;
2003                 rc        = established_get_idx(seq, pos);
2004         }
2005
2006         return rc;
2007 }
2008
2009 static void *tcp_seek_last_pos(struct seq_file *seq)
2010 {
2011         struct tcp_iter_state *st = seq->private;
2012         int offset = st->offset;
2013         int orig_num = st->num;
2014         void *rc = NULL;
2015
2016         switch (st->state) {
2017         case TCP_SEQ_STATE_OPENREQ:
2018         case TCP_SEQ_STATE_LISTENING:
2019                 if (st->bucket >= INET_LHTABLE_SIZE)
2020                         break;
2021                 st->state = TCP_SEQ_STATE_LISTENING;
2022                 rc = listening_get_next(seq, NULL);
2023                 while (offset-- && rc)
2024                         rc = listening_get_next(seq, rc);
2025                 if (rc)
2026                         break;
2027                 st->bucket = 0;
2028                 st->state = TCP_SEQ_STATE_ESTABLISHED;
2029                 /* Fallthrough */
2030         case TCP_SEQ_STATE_ESTABLISHED:
2031                 if (st->bucket > tcp_hashinfo.ehash_mask)
2032                         break;
2033                 rc = established_get_first(seq);
2034                 while (offset-- && rc)
2035                         rc = established_get_next(seq, rc);
2036         }
2037
2038         st->num = orig_num;
2039
2040         return rc;
2041 }
2042
2043 static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
2044 {
2045         struct tcp_iter_state *st = seq->private;
2046         void *rc;
2047
2048         if (*pos && *pos == st->last_pos) {
2049                 rc = tcp_seek_last_pos(seq);
2050                 if (rc)
2051                         goto out;
2052         }
2053
2054         st->state = TCP_SEQ_STATE_LISTENING;
2055         st->num = 0;
2056         st->bucket = 0;
2057         st->offset = 0;
2058         rc = *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
2059
2060 out:
2061         st->last_pos = *pos;
2062         return rc;
2063 }
2064
2065 static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2066 {
2067         struct tcp_iter_state *st = seq->private;
2068         void *rc = NULL;
2069
2070         if (v == SEQ_START_TOKEN) {
2071                 rc = tcp_get_idx(seq, 0);
2072                 goto out;
2073         }
2074
2075         switch (st->state) {
2076         case TCP_SEQ_STATE_OPENREQ:
2077         case TCP_SEQ_STATE_LISTENING:
2078                 rc = listening_get_next(seq, v);
2079                 if (!rc) {
2080                         st->state = TCP_SEQ_STATE_ESTABLISHED;
2081                         st->bucket = 0;
2082                         st->offset = 0;
2083                         rc        = established_get_first(seq);
2084                 }
2085                 break;
2086         case TCP_SEQ_STATE_ESTABLISHED:
2087                 rc = established_get_next(seq, v);
2088                 break;
2089         }
2090 out:
2091         ++*pos;
2092         st->last_pos = *pos;
2093         return rc;
2094 }
2095
2096 static void tcp_seq_stop(struct seq_file *seq, void *v)
2097 {
2098         struct tcp_iter_state *st = seq->private;
2099
2100         switch (st->state) {
2101         case TCP_SEQ_STATE_OPENREQ:
2102                 if (v) {
2103                         struct inet_connection_sock *icsk = inet_csk(st->syn_wait_sk);
2104                         spin_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2105                 }
2106         case TCP_SEQ_STATE_LISTENING:
2107                 if (v != SEQ_START_TOKEN)
2108                         spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock);
2109                 break;
2110         case TCP_SEQ_STATE_ESTABLISHED:
2111                 if (v)
2112                         spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2113                 break;
2114         }
2115 }
2116
2117 int tcp_seq_open(struct inode *inode, struct file *file)
2118 {
2119         struct tcp_seq_afinfo *afinfo = PDE_DATA(inode);
2120         struct tcp_iter_state *s;
2121         int err;
2122
2123         err = seq_open_net(inode, file, &afinfo->seq_ops,
2124                           sizeof(struct tcp_iter_state));
2125         if (err < 0)
2126                 return err;
2127
2128         s = ((struct seq_file *)file->private_data)->private;
2129         s->family               = afinfo->family;
2130         s->last_pos             = 0;
2131         return 0;
2132 }
2133 EXPORT_SYMBOL(tcp_seq_open);
2134
2135 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo)
2136 {
2137         int rc = 0;
2138         struct proc_dir_entry *p;
2139
2140         afinfo->seq_ops.start           = tcp_seq_start;
2141         afinfo->seq_ops.next            = tcp_seq_next;
2142         afinfo->seq_ops.stop            = tcp_seq_stop;
2143
2144         p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net,
2145                              afinfo->seq_fops, afinfo);
2146         if (!p)
2147                 rc = -ENOMEM;
2148         return rc;
2149 }
2150 EXPORT_SYMBOL(tcp_proc_register);
2151
2152 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo)
2153 {
2154         remove_proc_entry(afinfo->name, net->proc_net);
2155 }
2156 EXPORT_SYMBOL(tcp_proc_unregister);
2157
2158 static void get_openreq4(const struct request_sock *req,
2159                          struct seq_file *f, int i, kuid_t uid)
2160 {
2161         const struct inet_request_sock *ireq = inet_rsk(req);
2162         long delta = req->rsk_timer.expires - jiffies;
2163
2164         seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2165                 " %02X %08X:%08X %02X:%08lX %08X %5u %8d %u %d %pK",
2166                 i,
2167                 ireq->ir_loc_addr,
2168                 ireq->ir_num,
2169                 ireq->ir_rmt_addr,
2170                 ntohs(ireq->ir_rmt_port),
2171                 TCP_SYN_RECV,
2172                 0, 0, /* could print option size, but that is af dependent. */
2173                 1,    /* timers active (only the expire timer) */
2174                 jiffies_delta_to_clock_t(delta),
2175                 req->num_timeout,
2176                 from_kuid_munged(seq_user_ns(f), uid),
2177                 0,  /* non standard timer */
2178                 0, /* open_requests have no inode */
2179                 0,
2180                 req);
2181 }
2182
2183 static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i)
2184 {
2185         int timer_active;
2186         unsigned long timer_expires;
2187         const struct tcp_sock *tp = tcp_sk(sk);
2188         const struct inet_connection_sock *icsk = inet_csk(sk);
2189         const struct inet_sock *inet = inet_sk(sk);
2190         struct fastopen_queue *fastopenq = icsk->icsk_accept_queue.fastopenq;
2191         __be32 dest = inet->inet_daddr;
2192         __be32 src = inet->inet_rcv_saddr;
2193         __u16 destp = ntohs(inet->inet_dport);
2194         __u16 srcp = ntohs(inet->inet_sport);
2195         int rx_queue;
2196
2197         if (icsk->icsk_pending == ICSK_TIME_RETRANS ||
2198             icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS ||
2199             icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) {
2200                 timer_active    = 1;
2201                 timer_expires   = icsk->icsk_timeout;
2202         } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
2203                 timer_active    = 4;
2204                 timer_expires   = icsk->icsk_timeout;
2205         } else if (timer_pending(&sk->sk_timer)) {
2206                 timer_active    = 2;
2207                 timer_expires   = sk->sk_timer.expires;
2208         } else {
2209                 timer_active    = 0;
2210                 timer_expires = jiffies;
2211         }
2212
2213         if (sk->sk_state == TCP_LISTEN)
2214                 rx_queue = sk->sk_ack_backlog;
2215         else
2216                 /*
2217                  * because we dont lock socket, we might find a transient negative value
2218                  */
2219                 rx_queue = max_t(int, tp->rcv_nxt - tp->copied_seq, 0);
2220
2221         seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
2222                         "%08X %5u %8d %lu %d %pK %lu %lu %u %u %d",
2223                 i, src, srcp, dest, destp, sk->sk_state,
2224                 tp->write_seq - tp->snd_una,
2225                 rx_queue,
2226                 timer_active,
2227                 jiffies_delta_to_clock_t(timer_expires - jiffies),
2228                 icsk->icsk_retransmits,
2229                 from_kuid_munged(seq_user_ns(f), sock_i_uid(sk)),
2230                 icsk->icsk_probes_out,
2231                 sock_i_ino(sk),
2232                 atomic_read(&sk->sk_refcnt), sk,
2233                 jiffies_to_clock_t(icsk->icsk_rto),
2234                 jiffies_to_clock_t(icsk->icsk_ack.ato),
2235                 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
2236                 tp->snd_cwnd,
2237                 sk->sk_state == TCP_LISTEN ?
2238                     (fastopenq ? fastopenq->max_qlen : 0) :
2239                     (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh));
2240 }
2241
2242 static void get_timewait4_sock(const struct inet_timewait_sock *tw,
2243                                struct seq_file *f, int i)
2244 {
2245         long delta = tw->tw_timer.expires - jiffies;
2246         __be32 dest, src;
2247         __u16 destp, srcp;
2248
2249         dest  = tw->tw_daddr;
2250         src   = tw->tw_rcv_saddr;
2251         destp = ntohs(tw->tw_dport);
2252         srcp  = ntohs(tw->tw_sport);
2253
2254         seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2255                 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK",
2256                 i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
2257                 3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,
2258                 atomic_read(&tw->tw_refcnt), tw);
2259 }
2260
2261 #define TMPSZ 150
2262
2263 static int tcp4_seq_show(struct seq_file *seq, void *v)
2264 {
2265         struct tcp_iter_state *st;
2266         struct sock *sk = v;
2267
2268         seq_setwidth(seq, TMPSZ - 1);
2269         if (v == SEQ_START_TOKEN) {
2270                 seq_puts(seq, "  sl  local_address rem_address   st tx_queue "
2271                            "rx_queue tr tm->when retrnsmt   uid  timeout "
2272                            "inode");
2273                 goto out;
2274         }
2275         st = seq->private;
2276
2277         switch (st->state) {
2278         case TCP_SEQ_STATE_LISTENING:
2279         case TCP_SEQ_STATE_ESTABLISHED:
2280                 if (sk->sk_state == TCP_TIME_WAIT)
2281                         get_timewait4_sock(v, seq, st->num);
2282                 else
2283                         get_tcp4_sock(v, seq, st->num);
2284                 break;
2285         case TCP_SEQ_STATE_OPENREQ:
2286                 get_openreq4(v, seq, st->num, st->uid);
2287                 break;
2288         }
2289 out:
2290         seq_pad(seq, '\n');
2291         return 0;
2292 }
2293
2294 static const struct file_operations tcp_afinfo_seq_fops = {
2295         .owner   = THIS_MODULE,
2296         .open    = tcp_seq_open,
2297         .read    = seq_read,
2298         .llseek  = seq_lseek,
2299         .release = seq_release_net
2300 };
2301
2302 static struct tcp_seq_afinfo tcp4_seq_afinfo = {
2303         .name           = "tcp",
2304         .family         = AF_INET,
2305         .seq_fops       = &tcp_afinfo_seq_fops,
2306         .seq_ops        = {
2307                 .show           = tcp4_seq_show,
2308         },
2309 };
2310
2311 static int __net_init tcp4_proc_init_net(struct net *net)
2312 {
2313         return tcp_proc_register(net, &tcp4_seq_afinfo);
2314 }
2315
2316 static void __net_exit tcp4_proc_exit_net(struct net *net)
2317 {
2318         tcp_proc_unregister(net, &tcp4_seq_afinfo);
2319 }
2320
2321 static struct pernet_operations tcp4_net_ops = {
2322         .init = tcp4_proc_init_net,
2323         .exit = tcp4_proc_exit_net,
2324 };
2325
2326 int __init tcp4_proc_init(void)
2327 {
2328         return register_pernet_subsys(&tcp4_net_ops);
2329 }
2330
2331 void tcp4_proc_exit(void)
2332 {
2333         unregister_pernet_subsys(&tcp4_net_ops);
2334 }
2335 #endif /* CONFIG_PROC_FS */
2336
2337 struct proto tcp_prot = {
2338         .name                   = "TCP",
2339         .owner                  = THIS_MODULE,
2340         .close                  = tcp_close,
2341         .connect                = tcp_v4_connect,
2342         .disconnect             = tcp_disconnect,
2343         .accept                 = inet_csk_accept,
2344         .ioctl                  = tcp_ioctl,
2345         .init                   = tcp_v4_init_sock,
2346         .destroy                = tcp_v4_destroy_sock,
2347         .shutdown               = tcp_shutdown,
2348         .setsockopt             = tcp_setsockopt,
2349         .getsockopt             = tcp_getsockopt,
2350         .recvmsg                = tcp_recvmsg,
2351         .sendmsg                = tcp_sendmsg,
2352         .sendpage               = tcp_sendpage,
2353         .backlog_rcv            = tcp_v4_do_rcv,
2354         .release_cb             = tcp_release_cb,
2355         .hash                   = inet_hash,
2356         .unhash                 = inet_unhash,
2357         .get_port               = inet_csk_get_port,
2358         .enter_memory_pressure  = tcp_enter_memory_pressure,
2359         .stream_memory_free     = tcp_stream_memory_free,
2360         .sockets_allocated      = &tcp_sockets_allocated,
2361         .orphan_count           = &tcp_orphan_count,
2362         .memory_allocated       = &tcp_memory_allocated,
2363         .memory_pressure        = &tcp_memory_pressure,
2364         .sysctl_mem             = sysctl_tcp_mem,
2365         .sysctl_wmem            = sysctl_tcp_wmem,
2366         .sysctl_rmem            = sysctl_tcp_rmem,
2367         .max_header             = MAX_TCP_HEADER,
2368         .obj_size               = sizeof(struct tcp_sock),
2369         .slab_flags             = SLAB_DESTROY_BY_RCU,
2370         .twsk_prot              = &tcp_timewait_sock_ops,
2371         .rsk_prot               = &tcp_request_sock_ops,
2372         .h.hashinfo             = &tcp_hashinfo,
2373         .no_autobind            = true,
2374 #ifdef CONFIG_COMPAT
2375         .compat_setsockopt      = compat_tcp_setsockopt,
2376         .compat_getsockopt      = compat_tcp_getsockopt,
2377 #endif
2378 #ifdef CONFIG_MEMCG_KMEM
2379         .init_cgroup            = tcp_init_cgroup,
2380         .destroy_cgroup         = tcp_destroy_cgroup,
2381         .proto_cgroup           = tcp_proto_cgroup,
2382 #endif
2383 };
2384 EXPORT_SYMBOL(tcp_prot);
2385
2386 static void __net_exit tcp_sk_exit(struct net *net)
2387 {
2388         int cpu;
2389
2390         for_each_possible_cpu(cpu)
2391                 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.tcp_sk, cpu));
2392         free_percpu(net->ipv4.tcp_sk);
2393 }
2394
2395 static int __net_init tcp_sk_init(struct net *net)
2396 {
2397         int res, cpu;
2398
2399         net->ipv4.tcp_sk = alloc_percpu(struct sock *);
2400         if (!net->ipv4.tcp_sk)
2401                 return -ENOMEM;
2402
2403         for_each_possible_cpu(cpu) {
2404                 struct sock *sk;
2405
2406                 res = inet_ctl_sock_create(&sk, PF_INET, SOCK_RAW,
2407                                            IPPROTO_TCP, net);
2408                 if (res)
2409                         goto fail;
2410                 *per_cpu_ptr(net->ipv4.tcp_sk, cpu) = sk;
2411         }
2412         net->ipv4.sysctl_tcp_ecn = 2;
2413         net->ipv4.sysctl_tcp_base_mss = TCP_BASE_MSS;
2414         net->ipv4.sysctl_tcp_probe_threshold = TCP_PROBE_THRESHOLD;
2415         net->ipv4.sysctl_tcp_probe_interval = TCP_PROBE_INTERVAL;
2416         return 0;
2417
2418 fail:
2419         tcp_sk_exit(net);
2420
2421         return res;
2422 }
2423
2424 static void __net_exit tcp_sk_exit_batch(struct list_head *net_exit_list)
2425 {
2426         inet_twsk_purge(&tcp_hashinfo, &tcp_death_row, AF_INET);
2427 }
2428
2429 static struct pernet_operations __net_initdata tcp_sk_ops = {
2430        .init       = tcp_sk_init,
2431        .exit       = tcp_sk_exit,
2432        .exit_batch = tcp_sk_exit_batch,
2433 };
2434
2435 void __init tcp_v4_init(void)
2436 {
2437         inet_hashinfo_init(&tcp_hashinfo);
2438         if (register_pernet_subsys(&tcp_sk_ops))
2439                 panic("Failed to create the TCP control socket.\n");
2440 }