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   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  * Version:     $Id: tcp_ipv4.c,v 1.240 2002/02/01 22:01:04 davem Exp $
   9  *
  10  *              IPv4 specific functions
  11  *
  12  *
  13  *              code split from:
  14  *              linux/ipv4/tcp.c
  15  *              linux/ipv4/tcp_input.c
  16  *              linux/ipv4/tcp_output.c
  17  *
  18  *              See tcp.c for author information
  19  *
  20  *      This program is free software; you can redistribute it and/or
  21  *      modify it under the terms of the GNU General Public License
  22  *      as published by the Free Software Foundation; either version
  23  *      2 of the License, or (at your option) any later version.
  24  */
  25
  26 /*
  27  * Changes:
  28  *              David S. Miller :       New socket lookup architecture.
  29  *                                      This code is dedicated to John Dyson.
  30  *              David S. Miller :       Change semantics of established hash,
  31  *                                      half is devoted to TIME_WAIT sockets
  32  *                                      and the rest go in the other half.
  33  *              Andi Kleen :            Add support for syncookies and fixed
  34  *                                      some bugs: ip options weren't passed to
  35  *                                      the TCP layer, missed a check for an
  36  *                                      ACK bit.
  37  *              Andi Kleen :            Implemented fast path mtu discovery.
  38  *                                      Fixed many serious bugs in the
  39  *                                      request_sock handling and moved
  40  *                                      most of it into the af independent code.
  41  *                                      Added tail drop and some other bugfixes.
  42  *                                      Added new listen sematics.
  43  *              Mike McLagan    :       Routing by source
  44  *      Juan Jose Ciarlante:            ip_dynaddr bits
  45  *              Andi Kleen:             various fixes.
  46  *      Vitaly E. Lavrov        :       Transparent proxy revived after year
  47  *                                      coma.
  48  *      Andi Kleen              :       Fix new listen.
  49  *      Andi Kleen              :       Fix accept error reporting.
  50  *      YOSHIFUJI Hideaki @USAGI and:   Support IPV6_V6ONLY socket option, which
  51  *      Alexey Kuznetsov                allow both IPv4 and IPv6 sockets to bind
  52  *                                      a single port at the same time.
  53  */
  54
  55 #include <linux/config.h>
  56
  57 #include <linux/types.h>
  58 #include <linux/fcntl.h>
  59 #include <linux/module.h>
  60 #include <linux/random.h>
  61 #include <linux/cache.h>
  62 #include <linux/jhash.h>
  63 #include <linux/init.h>
  64 #include <linux/times.h>
  65
  66 #include <net/icmp.h>
  67 #include <net/inet_hashtables.h>
  68 #include <net/tcp.h>
  69 #include <net/transp_v6.h>
  70 #include <net/ipv6.h>
  71 #include <net/inet_common.h>
  72 #include <net/xfrm.h>
  73
  74 #include <linux/inet.h>
  75 #include <linux/ipv6.h>
  76 #include <linux/stddef.h>
  77 #include <linux/proc_fs.h>
  78 #include <linux/seq_file.h>
  79
  80 int sysctl_tcp_tw_reuse;
  81 int sysctl_tcp_low_latency;
  82
  83 /* Check TCP sequence numbers in ICMP packets. */
  84 #define ICMP_MIN_LENGTH 8
  85
  86 /* Socket used for sending RSTs */
  87 static struct socket *tcp_socket;
  88
  89 void tcp_v4_send_check(struct sock *sk, struct tcphdr *th, int len,
  90                        struct sk_buff *skb);
  91
  92 struct inet_hashinfo __cacheline_aligned tcp_hashinfo = {
  93         .lhash_lock     = RW_LOCK_UNLOCKED,
  94         .lhash_users    = ATOMIC_INIT(0),
  95         .lhash_wait     = __WAIT_QUEUE_HEAD_INITIALIZER(tcp_hashinfo.lhash_wait),
  96         .portalloc_lock = SPIN_LOCK_UNLOCKED,
  97         .port_rover     = 1024 - 1,
  98 };
  99
 100 static int tcp_v4_get_port(struct sock *sk, unsigned short snum)
 101 {
 102         return inet_csk_get_port(&tcp_hashinfo, sk, snum);
 103 }
 104
 105 static void tcp_v4_hash(struct sock *sk)
 106 {
 107         inet_hash(&tcp_hashinfo, sk);
 108 }
 109
 110 void tcp_unhash(struct sock *sk)
 111 {
 112         inet_unhash(&tcp_hashinfo, sk);
 113 }
 114
 115 static inline __u32 tcp_v4_init_sequence(struct sock *sk, struct sk_buff *skb)
 116 {
 117         return secure_tcp_sequence_number(skb->nh.iph->daddr,
 118                                           skb->nh.iph->saddr,
 119                                           skb->h.th->dest,
 120                                           skb->h.th->source);
 121 }
 122
 123 /* called with local bh disabled */
 124 static int __tcp_v4_check_established(struct sock *sk, __u16 lport,
 125                                       struct inet_timewait_sock **twp)
 126 {
 127         struct inet_sock *inet = inet_sk(sk);
 128         u32 daddr = inet->rcv_saddr;
 129         u32 saddr = inet->daddr;
 130         int dif = sk->sk_bound_dev_if;
 131         INET_ADDR_COOKIE(acookie, saddr, daddr)
 132         const __u32 ports = INET_COMBINED_PORTS(inet->dport, lport);
 133         unsigned int hash = inet_ehashfn(daddr, lport, saddr, inet->dport);
 134         struct inet_ehash_bucket *head = inet_ehash_bucket(&tcp_hashinfo, hash);
 135         struct sock *sk2;
 136         const struct hlist_node *node;
 137         struct inet_timewait_sock *tw;
 138
 139         prefetch(head->chain.first);
 140         write_lock(&head->lock);
 141
 142         /* Check TIME-WAIT sockets first. */
 143         sk_for_each(sk2, node, &(head + tcp_hashinfo.ehash_size)->chain) {
 144                 tw = inet_twsk(sk2);
 145
 146                 if (INET_TW_MATCH(sk2, hash, acookie, saddr, daddr, ports, dif)) {
 147                         const struct tcp_timewait_sock *tcptw = tcp_twsk(sk2);
 148                         struct tcp_sock *tp = tcp_sk(sk);
 149
 150                         /* With PAWS, it is safe from the viewpoint
 151                            of data integrity. Even without PAWS it
 152                            is safe provided sequence spaces do not
 153                            overlap i.e. at data rates <= 80Mbit/sec.
 154
 155                            Actually, the idea is close to VJ's one,
 156                            only timestamp cache is held not per host,
 157                            but per port pair and TW bucket is used
 158                            as state holder.
 159
 160                            If TW bucket has been already destroyed we
 161                            fall back to VJ's scheme and use initial
 162                            timestamp retrieved from peer table.
 163                          */
 164                         if (tcptw->tw_ts_recent_stamp &&
 165                             (!twp || (sysctl_tcp_tw_reuse &&
 166                                       xtime.tv_sec -
 167                                       tcptw->tw_ts_recent_stamp > 1))) {
 168                                 tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2;
 169                                 if (tp->write_seq == 0)
 170                                         tp->write_seq = 1;
 171                                 tp->rx_opt.ts_recent       = tcptw->tw_ts_recent;
 172                                 tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
 173                                 sock_hold(sk2);
 174                                 goto unique;
 175                         } else
 176                                 goto not_unique;
 177                 }
 178         }
 179         tw = NULL;
 180
 181         /* And established part... */
 182         sk_for_each(sk2, node, &head->chain) {
 183                 if (INET_MATCH(sk2, hash, acookie, saddr, daddr, ports, dif))
 184                         goto not_unique;
 185         }
 186
 187 unique:
 188         /* Must record num and sport now. Otherwise we will see
 189          * in hash table socket with a funny identity. */
 190         inet->num = lport;
 191         inet->sport = htons(lport);
 192         sk->sk_hash = hash;
 193         BUG_TRAP(sk_unhashed(sk));
 194         __sk_add_node(sk, &head->chain);
 195         sock_prot_inc_use(sk->sk_prot);
 196         write_unlock(&head->lock);
 197
 198         if (twp) {
 199                 *twp = tw;
 200                 NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
 201         } else if (tw) {
 202                 /* Silly. Should hash-dance instead... */
 203                 inet_twsk_deschedule(tw, &tcp_death_row);
 204                 NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
 205
 206                 inet_twsk_put(tw);
 207         }
 208
 209         return 0;
 210
 211 not_unique:
 212         write_unlock(&head->lock);
 213         return -EADDRNOTAVAIL;
 214 }
 215
 216 static inline u32 connect_port_offset(const struct sock *sk)
 217 {
 218         const struct inet_sock *inet = inet_sk(sk);
 219
 220         return secure_tcp_port_ephemeral(inet->rcv_saddr, inet->daddr,
 221                                          inet->dport);
 222 }
 223
 224 /*
 225  * Bind a port for a connect operation and hash it.
 226  */
 227 static inline int tcp_v4_hash_connect(struct sock *sk)
 228 {
 229         const unsigned short snum = inet_sk(sk)->num;
 230         struct inet_bind_hashbucket *head;
 231         struct inet_bind_bucket *tb;
 232         int ret;
 233
 234         if (!snum) {
 235                 int low = sysctl_local_port_range[0];
 236                 int high = sysctl_local_port_range[1];
 237                 int range = high - low;
 238                 int i;
 239                 int port;
 240                 static u32 hint;
 241                 u32 offset = hint + connect_port_offset(sk);
 242                 struct hlist_node *node;
 243                 struct inet_timewait_sock *tw = NULL;
 244
 245                 local_bh_disable();
 246                 for (i = 1; i <= range; i++) {
 247                         port = low + (i + offset) % range;
 248                         head = &tcp_hashinfo.bhash[inet_bhashfn(port, tcp_hashinfo.bhash_size)];
 249                         spin_lock(&head->lock);
 250
 251                         /* Does not bother with rcv_saddr checks,
 252                          * because the established check is already
 253                          * unique enough.
 254                          */
 255                         inet_bind_bucket_for_each(tb, node, &head->chain) {
 256                                 if (tb->port == port) {
 257                                         BUG_TRAP(!hlist_empty(&tb->owners));
 258                                         if (tb->fastreuse >= 0)
 259                                                 goto next_port;
 260                                         if (!__tcp_v4_check_established(sk,
 261                                                                         port,
 262                                                                         &tw))
 263                                                 goto ok;
 264                                         goto next_port;
 265                                 }
 266                         }
 267
 268                         tb = inet_bind_bucket_create(tcp_hashinfo.bind_bucket_cachep, head, port);
 269                         if (!tb) {
 270                                 spin_unlock(&head->lock);
 271                                 break;
 272                         }
 273                         tb->fastreuse = -1;
 274                         goto ok;
 275
 276                 next_port:
 277                         spin_unlock(&head->lock);
 278                 }
 279                 local_bh_enable();
 280
 281                 return -EADDRNOTAVAIL;
 282
 283 ok:
 284                 hint += i;
 285
 286                 /* Head lock still held and bh's disabled */
 287                 inet_bind_hash(sk, tb, port);
 288                 if (sk_unhashed(sk)) {
 289                         inet_sk(sk)->sport = htons(port);
 290                         __inet_hash(&tcp_hashinfo, sk, 0);
 291                 }
 292                 spin_unlock(&head->lock);
 293
 294                 if (tw) {
 295                         inet_twsk_deschedule(tw, &tcp_death_row);;
 296                         inet_twsk_put(tw);
 297                 }
 298
 299                 ret = 0;
 300                 goto out;
 301         }
 302
 303         head = &tcp_hashinfo.bhash[inet_bhashfn(snum, tcp_hashinfo.bhash_size)];
 304         tb  = inet_csk(sk)->icsk_bind_hash;
 305         spin_lock_bh(&head->lock);
 306         if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
 307                 __inet_hash(&tcp_hashinfo, sk, 0);
 308                 spin_unlock_bh(&head->lock);
 309                 return 0;
 310         } else {
 311                 spin_unlock(&head->lock);
 312                 /* No definite answer... Walk to established hash table */
 313                 ret = __tcp_v4_check_established(sk, snum, NULL);
 314 out:
 315                 local_bh_enable();
 316                 return ret;
 317         }
 318 }
 319
 320 /* This will initiate an outgoing connection. */
 321 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 322 {
 323         struct inet_sock *inet = inet_sk(sk);
 324         struct tcp_sock *tp = tcp_sk(sk);
 325         struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
 326         struct rtable *rt;
 327         u32 daddr, nexthop;
 328         int tmp;
 329         int err;
 330
 331         if (addr_len < sizeof(struct sockaddr_in))
 332                 return -EINVAL;
 333
 334         if (usin->sin_family != AF_INET)
 335                 return -EAFNOSUPPORT;
 336
 337         nexthop = daddr = usin->sin_addr.s_addr;
 338         if (inet->opt && inet->opt->srr) {
 339                 if (!daddr)
 340                         return -EINVAL;
 341                 nexthop = inet->opt->faddr;
 342         }
 343
 344         tmp = ip_route_connect(&rt, nexthop, inet->saddr,
 345                                RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
 346                                IPPROTO_TCP,
 347                                inet->sport, usin->sin_port, sk);
 348         if (tmp < 0)
 349                 return tmp;
 350
 351         if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
 352                 ip_rt_put(rt);
 353                 return -ENETUNREACH;
 354         }
 355
 356         if (!inet->opt || !inet->opt->srr)
 357                 daddr = rt->rt_dst;
 358
 359         if (!inet->saddr)
 360                 inet->saddr = rt->rt_src;
 361         inet->rcv_saddr = inet->saddr;
 362
 363         if (tp->rx_opt.ts_recent_stamp && inet->daddr != daddr) {
 364                 /* Reset inherited state */
 365                 tp->rx_opt.ts_recent       = 0;
 366                 tp->rx_opt.ts_recent_stamp = 0;
 367                 tp->write_seq              = 0;
 368         }
 369
 370         if (tcp_death_row.sysctl_tw_recycle &&
 371             !tp->rx_opt.ts_recent_stamp && rt->rt_dst == daddr) {
 372                 struct inet_peer *peer = rt_get_peer(rt);
 373
 374                 /* VJ's idea. We save last timestamp seen from
 375                  * the destination in peer table, when entering state TIME-WAIT
 376                  * and initialize rx_opt.ts_recent from it, when trying new connection.
 377                  */
 378
 379                 if (peer && peer->tcp_ts_stamp + TCP_PAWS_MSL >= xtime.tv_sec) {
 380                         tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp;
 381                         tp->rx_opt.ts_recent = peer->tcp_ts;
 382                 }
 383         }
 384
 385         inet->dport = usin->sin_port;
 386         inet->daddr = daddr;
 387
 388         tp->ext_header_len = 0;
 389         if (inet->opt)
 390                 tp->ext_header_len = inet->opt->optlen;
 391
 392         tp->rx_opt.mss_clamp = 536;
 393
 394         /* Socket identity is still unknown (sport may be zero).
 395          * However we set state to SYN-SENT and not releasing socket
 396          * lock select source port, enter ourselves into the hash tables and
 397          * complete initialization after this.
 398          */
 399         tcp_set_state(sk, TCP_SYN_SENT);
 400         err = tcp_v4_hash_connect(sk);
 401         if (err)
 402                 goto failure;
 403
 404         err = ip_route_newports(&rt, inet->sport, inet->dport, sk);
 405         if (err)
 406                 goto failure;
 407
 408         /* OK, now commit destination to socket.  */
 409         sk_setup_caps(sk, &rt->u.dst);
 410
 411         if (!tp->write_seq)
 412                 tp->write_seq = secure_tcp_sequence_number(inet->saddr,
 413                                                            inet->daddr,
 414                                                            inet->sport,
 415                                                            usin->sin_port);
 416
 417         inet->id = tp->write_seq ^ jiffies;
 418
 419         err = tcp_connect(sk);
 420         rt = NULL;
 421         if (err)
 422                 goto failure;
 423
 424         return 0;
 425
 426 failure:
 427         /* This unhashes the socket and releases the local port, if necessary. */
 428         tcp_set_state(sk, TCP_CLOSE);
 429         ip_rt_put(rt);
 430         sk->sk_route_caps = 0;
 431         inet->dport = 0;
 432         return err;
 433 }
 434
 435 /*
 436  * This routine does path mtu discovery as defined in RFC1191.
 437  */
 438 static inline void do_pmtu_discovery(struct sock *sk, struct iphdr *iph,
 439                                      u32 mtu)
 440 {
 441         struct dst_entry *dst;
 442         struct inet_sock *inet = inet_sk(sk);
 443         struct tcp_sock *tp = tcp_sk(sk);
 444
 445         /* We are not interested in TCP_LISTEN and open_requests (SYN-ACKs
 446          * send out by Linux are always <576bytes so they should go through
 447          * unfragmented).
 448          */
 449         if (sk->sk_state == TCP_LISTEN)
 450                 return;
 451
 452         /* We don't check in the destentry if pmtu discovery is forbidden
 453          * on this route. We just assume that no packet_to_big packets
 454          * are send back when pmtu discovery is not active.
 455          * There is a small race when the user changes this flag in the
 456          * route, but I think that's acceptable.
 457          */
 458         if ((dst = __sk_dst_check(sk, 0)) == NULL)
 459                 return;
 460
 461         dst->ops->update_pmtu(dst, mtu);
 462
 463         /* Something is about to be wrong... Remember soft error
 464          * for the case, if this connection will not able to recover.
 465          */
 466         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
 467                 sk->sk_err_soft = EMSGSIZE;
 468
 469         mtu = dst_mtu(dst);
 470
 471         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
 472             tp->pmtu_cookie > mtu) {
 473                 tcp_sync_mss(sk, mtu);
 474
 475                 /* Resend the TCP packet because it's
 476                  * clear that the old packet has been
 477                  * dropped. This is the new "fast" path mtu
 478                  * discovery.
 479                  */
 480                 tcp_simple_retransmit(sk);
 481         } /* else let the usual retransmit timer handle it */
 482 }
 483
 484 /*
 485  * This routine is called by the ICMP module when it gets some
 486  * sort of error condition.  If err < 0 then the socket should
 487  * be closed and the error returned to the user.  If err > 0
 488  * it's just the icmp type << 8 | icmp code.  After adjustment
 489  * header points to the first 8 bytes of the tcp header.  We need
 490  * to find the appropriate port.
 491  *
 492  * The locking strategy used here is very "optimistic". When
 493  * someone else accesses the socket the ICMP is just dropped
 494  * and for some paths there is no check at all.
 495  * A more general error queue to queue errors for later handling
 496  * is probably better.
 497  *
 498  */
 499
 500 void tcp_v4_err(struct sk_buff *skb, u32 info)
 501 {
 502         struct iphdr *iph = (struct iphdr *)skb->data;
 503         struct tcphdr *th = (struct tcphdr *)(skb->data + (iph->ihl << 2));
 504         struct tcp_sock *tp;
 505         struct inet_sock *inet;
 506         int type = skb->h.icmph->type;
 507         int code = skb->h.icmph->code;
 508         struct sock *sk;
 509         __u32 seq;
 510         int err;
 511
 512         if (skb->len < (iph->ihl << 2) + 8) {
 513                 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
 514                 return;
 515         }
 516
 517         sk = inet_lookup(&tcp_hashinfo, iph->daddr, th->dest, iph->saddr,
 518                          th->source, inet_iif(skb));
 519         if (!sk) {
 520                 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
 521                 return;
 522         }
 523         if (sk->sk_state == TCP_TIME_WAIT) {
 524                 inet_twsk_put((struct inet_timewait_sock *)sk);
 525                 return;
 526         }
 527
 528         bh_lock_sock(sk);
 529         /* If too many ICMPs get dropped on busy
 530          * servers this needs to be solved differently.
 531          */
 532         if (sock_owned_by_user(sk))
 533                 NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS);
 534
 535         if (sk->sk_state == TCP_CLOSE)
 536                 goto out;
 537
 538         tp = tcp_sk(sk);
 539         seq = ntohl(th->seq);
 540         if (sk->sk_state != TCP_LISTEN &&
 541             !between(seq, tp->snd_una, tp->snd_nxt)) {
 542                 NET_INC_STATS(LINUX_MIB_OUTOFWINDOWICMPS);
 543                 goto out;
 544         }
 545
 546         switch (type) {
 547         case ICMP_SOURCE_QUENCH:
 548                 /* Just silently ignore these. */
 549                 goto out;
 550         case ICMP_PARAMETERPROB:
 551                 err = EPROTO;
 552                 break;
 553         case ICMP_DEST_UNREACH:
 554                 if (code > NR_ICMP_UNREACH)
 555                         goto out;
 556
 557                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
 558                         if (!sock_owned_by_user(sk))
 559                                 do_pmtu_discovery(sk, iph, info);
 560                         goto out;
 561                 }
 562
 563                 err = icmp_err_convert[code].errno;
 564                 break;
 565         case ICMP_TIME_EXCEEDED:
 566                 err = EHOSTUNREACH;
 567                 break;
 568         default:
 569                 goto out;
 570         }
 571
 572         switch (sk->sk_state) {
 573                 struct request_sock *req, **prev;
 574         case TCP_LISTEN:
 575                 if (sock_owned_by_user(sk))
 576                         goto out;
 577
 578                 req = inet_csk_search_req(sk, &prev, th->dest,
 579                                           iph->daddr, iph->saddr);
 580                 if (!req)
 581                         goto out;
 582
 583                 /* ICMPs are not backlogged, hence we cannot get
 584                    an established socket here.
 585                  */
 586                 BUG_TRAP(!req->sk);
 587
 588                 if (seq != tcp_rsk(req)->snt_isn) {
 589                         NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
 590                         goto out;
 591                 }
 592
 593                 /*
 594                  * Still in SYN_RECV, just remove it silently.
 595                  * There is no good way to pass the error to the newly
 596                  * created socket, and POSIX does not want network
 597                  * errors returned from accept().
 598                  */
 599                 inet_csk_reqsk_queue_drop(sk, req, prev);
 600                 goto out;
 601
 602         case TCP_SYN_SENT:
 603         case TCP_SYN_RECV:  /* Cannot happen.
 604                                It can f.e. if SYNs crossed.
 605                              */
 606                 if (!sock_owned_by_user(sk)) {
 607                         TCP_INC_STATS_BH(TCP_MIB_ATTEMPTFAILS);
 608                         sk->sk_err = err;
 609
 610                         sk->sk_error_report(sk);
 611
 612                         tcp_done(sk);
 613                 } else {
 614                         sk->sk_err_soft = err;
 615                 }
 616                 goto out;
 617         }
 618
 619         /* If we've already connected we will keep trying
 620          * until we time out, or the user gives up.
 621          *
 622          * rfc1122 4.2.3.9 allows to consider as hard errors
 623          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
 624          * but it is obsoleted by pmtu discovery).
 625          *
 626          * Note, that in modern internet, where routing is unreliable
 627          * and in each dark corner broken firewalls sit, sending random
 628          * errors ordered by their masters even this two messages finally lose
 629          * their original sense (even Linux sends invalid PORT_UNREACHs)
 630          *
 631          * Now we are in compliance with RFCs.
 632          *                                                      --ANK (980905)
 633          */
 634
 635         inet = inet_sk(sk);
 636         if (!sock_owned_by_user(sk) && inet->recverr) {
 637                 sk->sk_err = err;
 638                 sk->sk_error_report(sk);
 639         } else  { /* Only an error on timeout */
 640                 sk->sk_err_soft = err;
 641         }
 642
 643 out:
 644         bh_unlock_sock(sk);
 645         sock_put(sk);
 646 }
 647
 648 /* This routine computes an IPv4 TCP checksum. */
 649 void tcp_v4_send_check(struct sock *sk, struct tcphdr *th, int len,
 650                        struct sk_buff *skb)
 651 {
 652         struct inet_sock *inet = inet_sk(sk);
 653
 654         if (skb->ip_summed == CHECKSUM_HW) {
 655                 th->check = ~tcp_v4_check(th, len, inet->saddr, inet->daddr, 0);
 656                 skb->csum = offsetof(struct tcphdr, check);
 657         } else {
 658                 th->check = tcp_v4_check(th, len, inet->saddr, inet->daddr,
 659                                          csum_partial((char *)th,
 660                                                       th->doff << 2,
 661                                                       skb->csum));
 662         }
 663 }
 664
 665 /*
 666  *      This routine will send an RST to the other tcp.
 667  *
 668  *      Someone asks: why I NEVER use socket parameters (TOS, TTL etc.)
 669  *                    for reset.
 670  *      Answer: if a packet caused RST, it is not for a socket
 671  *              existing in our system, if it is matched to a socket,
 672  *              it is just duplicate segment or bug in other side's TCP.
 673  *              So that we build reply only basing on parameters
 674  *              arrived with segment.
 675  *      Exception: precedence violation. We do not implement it in any case.
 676  */
 677
 678 static void tcp_v4_send_reset(struct sk_buff *skb)
 679 {
 680         struct tcphdr *th = skb->h.th;
 681         struct tcphdr rth;
 682         struct ip_reply_arg arg;
 683
 684         /* Never send a reset in response to a reset. */
 685         if (th->rst)
 686                 return;
 687
 688         if (((struct rtable *)skb->dst)->rt_type != RTN_LOCAL)
 689                 return;
 690
 691         /* Swap the send and the receive. */
 692         memset(&rth, 0, sizeof(struct tcphdr));
 693         rth.dest   = th->source;
 694         rth.source = th->dest;
 695         rth.doff   = sizeof(struct tcphdr) / 4;
 696         rth.rst    = 1;
 697
 698         if (th->ack) {
 699                 rth.seq = th->ack_seq;
 700         } else {
 701                 rth.ack = 1;
 702                 rth.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin +
 703                                     skb->len - (th->doff << 2));
 704         }
 705
 706         memset(&arg, 0, sizeof arg);
 707         arg.iov[0].iov_base = (unsigned char *)&rth;
 708         arg.iov[0].iov_len  = sizeof rth;
 709         arg.csum = csum_tcpudp_nofold(skb->nh.iph->daddr,
 710                                       skb->nh.iph->saddr, /*XXX*/
 711                                       sizeof(struct tcphdr), IPPROTO_TCP, 0);
 712         arg.csumoffset = offsetof(struct tcphdr, check) / 2;
 713
 714         ip_send_reply(tcp_socket->sk, skb, &arg, sizeof rth);
 715
 716         TCP_INC_STATS_BH(TCP_MIB_OUTSEGS);
 717         TCP_INC_STATS_BH(TCP_MIB_OUTRSTS);
 718 }
 719
 720 /* The code following below sending ACKs in SYN-RECV and TIME-WAIT states
 721    outside socket context is ugly, certainly. What can I do?
 722  */
 723
 724 static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
 725                             u32 win, u32 ts)
 726 {
 727         struct tcphdr *th = skb->h.th;
 728         struct {
 729                 struct tcphdr th;
 730                 u32 tsopt[3];
 731         } rep;
 732         struct ip_reply_arg arg;
 733
 734         memset(&rep.th, 0, sizeof(struct tcphdr));
 735         memset(&arg, 0, sizeof arg);
 736
 737         arg.iov[0].iov_base = (unsigned char *)&rep;
 738         arg.iov[0].iov_len  = sizeof(rep.th);
 739         if (ts) {
 740                 rep.tsopt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
 741                                      (TCPOPT_TIMESTAMP << 8) |
 742                                      TCPOLEN_TIMESTAMP);
 743                 rep.tsopt[1] = htonl(tcp_time_stamp);
 744                 rep.tsopt[2] = htonl(ts);
 745                 arg.iov[0].iov_len = sizeof(rep);
 746         }
 747
 748         /* Swap the send and the receive. */
 749         rep.th.dest    = th->source;
 750         rep.th.source  = th->dest;
 751         rep.th.doff    = arg.iov[0].iov_len / 4;
 752         rep.th.seq     = htonl(seq);
 753         rep.th.ack_seq = htonl(ack);
 754         rep.th.ack     = 1;
 755         rep.th.window  = htons(win);
 756
 757         arg.csum = csum_tcpudp_nofold(skb->nh.iph->daddr,
 758                                       skb->nh.iph->saddr, /*XXX*/
 759                                       arg.iov[0].iov_len, IPPROTO_TCP, 0);
 760         arg.csumoffset = offsetof(struct tcphdr, check) / 2;
 761
 762         ip_send_reply(tcp_socket->sk, skb, &arg, arg.iov[0].iov_len);
 763
 764         TCP_INC_STATS_BH(TCP_MIB_OUTSEGS);
 765 }
 766
 767 static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
 768 {
 769         struct inet_timewait_sock *tw = inet_twsk(sk);
 770         const struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
 771
 772         tcp_v4_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
 773                         tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale, tcptw->tw_ts_recent);
 774
 775         inet_twsk_put(tw);
 776 }
 777
 778 static void tcp_v4_reqsk_send_ack(struct sk_buff *skb, struct request_sock *req)
 779 {
 780         tcp_v4_send_ack(skb, tcp_rsk(req)->snt_isn + 1, tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd,
 781                         req->ts_recent);
 782 }
 783
 784 /*
 785  *      Send a SYN-ACK after having received an ACK.
 786  *      This still operates on a request_sock only, not on a big
 787  *      socket.
 788  */
 789 static int tcp_v4_send_synack(struct sock *sk, struct request_sock *req,
 790                               struct dst_entry *dst)
 791 {
 792         const struct inet_request_sock *ireq = inet_rsk(req);
 793         int err = -1;
 794         struct sk_buff * skb;
 795
 796         /* First, grab a route. */
 797         if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
 798                 goto out;
 799
 800         skb = tcp_make_synack(sk, dst, req);
 801
 802         if (skb) {
 803                 struct tcphdr *th = skb->h.th;
 804
 805                 th->check = tcp_v4_check(th, skb->len,
 806                                          ireq->loc_addr,
 807                                          ireq->rmt_addr,
 808                                          csum_partial((char *)th, skb->len,
 809                                                       skb->csum));
 810
 811                 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
 812                                             ireq->rmt_addr,
 813                                             ireq->opt);
 814                 if (err == NET_XMIT_CN)
 815                         err = 0;
 816         }
 817
 818 out:
 819         dst_release(dst);
 820         return err;
 821 }
 822
 823 /*
 824  *      IPv4 request_sock destructor.
 825  */
 826 static void tcp_v4_reqsk_destructor(struct request_sock *req)
 827 {
 828         if (inet_rsk(req)->opt)
 829                 kfree(inet_rsk(req)->opt);
 830 }
 831
 832 static inline void syn_flood_warning(struct sk_buff *skb)
 833 {
 834         static unsigned long warntime;
 835
 836         if (time_after(jiffies, (warntime + HZ * 60))) {
 837                 warntime = jiffies;
 838                 printk(KERN_INFO
 839                        "possible SYN flooding on port %d. Sending cookies.\n",
 840                        ntohs(skb->h.th->dest));
 841         }
 842 }
 843
 844 /*
 845  * Save and compile IPv4 options into the request_sock if needed.
 846  */
 847 static inline struct ip_options *tcp_v4_save_options(struct sock *sk,
 848                                                      struct sk_buff *skb)
 849 {
 850         struct ip_options *opt = &(IPCB(skb)->opt);
 851         struct ip_options *dopt = NULL;
 852
 853         if (opt && opt->optlen) {
 854                 int opt_size = optlength(opt);
 855                 dopt = kmalloc(opt_size, GFP_ATOMIC);
 856                 if (dopt) {
 857                         if (ip_options_echo(dopt, skb)) {
 858                                 kfree(dopt);
 859                                 dopt = NULL;
 860                         }
 861                 }
 862         }
 863         return dopt;
 864 }
 865
 866 struct request_sock_ops tcp_request_sock_ops = {
 867         .family         =       PF_INET,
 868         .obj_size       =       sizeof(struct tcp_request_sock),
 869         .rtx_syn_ack    =       tcp_v4_send_synack,
 870         .send_ack       =       tcp_v4_reqsk_send_ack,
 871         .destructor     =       tcp_v4_reqsk_destructor,
 872         .send_reset     =       tcp_v4_send_reset,
 873 };
 874
 875 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 876 {
 877         struct inet_request_sock *ireq;
 878         struct tcp_options_received tmp_opt;
 879         struct request_sock *req;
 880         __u32 saddr = skb->nh.iph->saddr;
 881         __u32 daddr = skb->nh.iph->daddr;
 882         __u32 isn = TCP_SKB_CB(skb)->when;
 883         struct dst_entry *dst = NULL;
 884 #ifdef CONFIG_SYN_COOKIES
 885         int want_cookie = 0;
 886 #else
 887 #define want_cookie 0 /* Argh, why doesn't gcc optimize this :( */
 888 #endif
 889
 890         /* Never answer to SYNs send to broadcast or multicast */
 891         if (((struct rtable *)skb->dst)->rt_flags &
 892             (RTCF_BROADCAST | RTCF_MULTICAST))
 893                 goto drop;
 894
 895         /* TW buckets are converted to open requests without
 896          * limitations, they conserve resources and peer is
 897          * evidently real one.
 898          */
 899         if (inet_csk_reqsk_queue_is_full(sk) && !isn) {
 900 #ifdef CONFIG_SYN_COOKIES
 901                 if (sysctl_tcp_syncookies) {
 902                         want_cookie = 1;
 903                 } else
 904 #endif
 905                 goto drop;
 906         }
 907
 908         /* Accept backlog is full. If we have already queued enough
 909          * of warm entries in syn queue, drop request. It is better than
 910          * clogging syn queue with openreqs with exponentially increasing
 911          * timeout.
 912          */
 913         if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
 914                 goto drop;
 915
 916         req = reqsk_alloc(&tcp_request_sock_ops);
 917         if (!req)
 918                 goto drop;
 919
 920         tcp_clear_options(&tmp_opt);
 921         tmp_opt.mss_clamp = 536;
 922         tmp_opt.user_mss  = tcp_sk(sk)->rx_opt.user_mss;
 923
 924         tcp_parse_options(skb, &tmp_opt, 0);
 925
 926         if (want_cookie) {
 927                 tcp_clear_options(&tmp_opt);
 928                 tmp_opt.saw_tstamp = 0;
 929         }
 930
 931         if (tmp_opt.saw_tstamp && !tmp_opt.rcv_tsval) {
 932                 /* Some OSes (unknown ones, but I see them on web server, which
 933                  * contains information interesting only for windows'
 934                  * users) do not send their stamp in SYN. It is easy case.
 935                  * We simply do not advertise TS support.
 936                  */
 937                 tmp_opt.saw_tstamp = 0;
 938                 tmp_opt.tstamp_ok  = 0;
 939         }
 940         tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
 941
 942         tcp_openreq_init(req, &tmp_opt, skb);
 943
 944         ireq = inet_rsk(req);
 945         ireq->loc_addr = daddr;
 946         ireq->rmt_addr = saddr;
 947         ireq->opt = tcp_v4_save_options(sk, skb);
 948         if (!want_cookie)
 949                 TCP_ECN_create_request(req, skb->h.th);
 950
 951         if (want_cookie) {
 952 #ifdef CONFIG_SYN_COOKIES
 953                 syn_flood_warning(skb);
 954 #endif
 955                 isn = cookie_v4_init_sequence(sk, skb, &req->mss);
 956         } else if (!isn) {
 957                 struct inet_peer *peer = NULL;
 958
 959                 /* VJ's idea. We save last timestamp seen
 960                  * from the destination in peer table, when entering
 961                  * state TIME-WAIT, and check against it before
 962                  * accepting new connection request.
 963                  *
 964                  * If "isn" is not zero, this request hit alive
 965                  * timewait bucket, so that all the necessary checks
 966                  * are made in the function processing timewait state.
 967                  */
 968                 if (tmp_opt.saw_tstamp &&
 969                     tcp_death_row.sysctl_tw_recycle &&
 970                     (dst = inet_csk_route_req(sk, req)) != NULL &&
 971                     (peer = rt_get_peer((struct rtable *)dst)) != NULL &&
 972                     peer->v4daddr == saddr) {
 973                         if (xtime.tv_sec < peer->tcp_ts_stamp + TCP_PAWS_MSL &&
 974                             (s32)(peer->tcp_ts - req->ts_recent) >
 975                                                         TCP_PAWS_WINDOW) {
 976                                 NET_INC_STATS_BH(LINUX_MIB_PAWSPASSIVEREJECTED);
 977                                 dst_release(dst);
 978                                 goto drop_and_free;
 979                         }
 980                 }
 981                 /* Kill the following clause, if you dislike this way. */
 982                 else if (!sysctl_tcp_syncookies &&
 983                          (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
 984                           (sysctl_max_syn_backlog >> 2)) &&
 985                          (!peer || !peer->tcp_ts_stamp) &&
 986                          (!dst || !dst_metric(dst, RTAX_RTT))) {
 987                         /* Without syncookies last quarter of
 988                          * backlog is filled with destinations,
 989                          * proven to be alive.
 990                          * It means that we continue to communicate
 991                          * to destinations, already remembered
 992                          * to the moment of synflood.
 993                          */
 994                         LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open "
 995                                        "request from %u.%u.%u.%u/%u\n",
 996                                        NIPQUAD(saddr),
 997                                        ntohs(skb->h.th->source));
 998                         dst_release(dst);
 999                         goto drop_and_free;
1000                 }
1001
1002                 isn = tcp_v4_init_sequence(sk, skb);
1003         }
1004         tcp_rsk(req)->snt_isn = isn;
1005
1006         if (tcp_v4_send_synack(sk, req, dst))
1007                 goto drop_and_free;
1008
1009         if (want_cookie) {
1010                 reqsk_free(req);
1011         } else {
1012                 inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
1013         }
1014         return 0;
1015
1016 drop_and_free:
1017         reqsk_free(req);
1018 drop:
1019         TCP_INC_STATS_BH(TCP_MIB_ATTEMPTFAILS);
1020         return 0;
1021 }
1022
1023
1024 /*
1025  * The three way handshake has completed - we got a valid synack -
1026  * now create the new socket.
1027  */
1028 struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
1029                                   struct request_sock *req,
1030                                   struct dst_entry *dst)
1031 {
1032         struct inet_request_sock *ireq;
1033         struct inet_sock *newinet;
1034         struct tcp_sock *newtp;
1035         struct sock *newsk;
1036
1037         if (sk_acceptq_is_full(sk))
1038                 goto exit_overflow;
1039
1040         if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
1041                 goto exit;
1042
1043         newsk = tcp_create_openreq_child(sk, req, skb);
1044         if (!newsk)
1045                 goto exit;
1046
1047         sk_setup_caps(newsk, dst);
1048
1049         newtp                 = tcp_sk(newsk);
1050         newinet               = inet_sk(newsk);
1051         ireq                  = inet_rsk(req);
1052         newinet->daddr        = ireq->rmt_addr;
1053         newinet->rcv_saddr    = ireq->loc_addr;
1054         newinet->saddr        = ireq->loc_addr;
1055         newinet->opt          = ireq->opt;
1056         ireq->opt             = NULL;
1057         newinet->mc_index     = inet_iif(skb);
1058         newinet->mc_ttl       = skb->nh.iph->ttl;
1059         newtp->ext_header_len = 0;
1060         if (newinet->opt)
1061                 newtp->ext_header_len = newinet->opt->optlen;
1062         newinet->id = newtp->write_seq ^ jiffies;
1063
1064         tcp_sync_mss(newsk, dst_mtu(dst));
1065         newtp->advmss = dst_metric(dst, RTAX_ADVMSS);
1066         tcp_initialize_rcv_mss(newsk);
1067
1068         __inet_hash(&tcp_hashinfo, newsk, 0);
1069         __inet_inherit_port(&tcp_hashinfo, sk, newsk);
1070
1071         return newsk;
1072
1073 exit_overflow:
1074         NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS);
1075 exit:
1076         NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS);
1077         dst_release(dst);
1078         return NULL;
1079 }
1080
1081 static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
1082 {
1083         struct tcphdr *th = skb->h.th;
1084         struct iphdr *iph = skb->nh.iph;
1085         struct sock *nsk;
1086         struct request_sock **prev;
1087         /* Find possible connection requests. */
1088         struct request_sock *req = inet_csk_search_req(sk, &prev, th->source,
1089                                                        iph->saddr, iph->daddr);
1090         if (req)
1091                 return tcp_check_req(sk, skb, req, prev);
1092
1093         nsk = __inet_lookup_established(&tcp_hashinfo, skb->nh.iph->saddr,
1094                                         th->source, skb->nh.iph->daddr,
1095                                         ntohs(th->dest), inet_iif(skb));
1096
1097         if (nsk) {
1098                 if (nsk->sk_state != TCP_TIME_WAIT) {
1099                         bh_lock_sock(nsk);
1100                         return nsk;
1101                 }
1102                 inet_twsk_put((struct inet_timewait_sock *)nsk);
1103                 return NULL;
1104         }
1105
1106 #ifdef CONFIG_SYN_COOKIES
1107         if (!th->rst && !th->syn && th->ack)
1108                 sk = cookie_v4_check(sk, skb, &(IPCB(skb)->opt));
1109 #endif
1110         return sk;
1111 }
1112
1113 static int tcp_v4_checksum_init(struct sk_buff *skb)
1114 {
1115         if (skb->ip_summed == CHECKSUM_HW) {
1116                 skb->ip_summed = CHECKSUM_UNNECESSARY;
1117                 if (!tcp_v4_check(skb->h.th, skb->len, skb->nh.iph->saddr,
1118                                   skb->nh.iph->daddr, skb->csum))
1119                         return 0;
1120
1121                 LIMIT_NETDEBUG(KERN_DEBUG "hw tcp v4 csum failed\n");
1122                 skb->ip_summed = CHECKSUM_NONE;
1123         }
1124         if (skb->len <= 76) {
1125                 if (tcp_v4_check(skb->h.th, skb->len, skb->nh.iph->saddr,
1126                                  skb->nh.iph->daddr,
1127                                  skb_checksum(skb, 0, skb->len, 0)))
1128                         return -1;
1129                 skb->ip_summed = CHECKSUM_UNNECESSARY;
1130         } else {
1131                 skb->csum = ~tcp_v4_check(skb->h.th, skb->len,
1132                                           skb->nh.iph->saddr,
1133                                           skb->nh.iph->daddr, 0);
1134         }
1135         return 0;
1136 }
1137
1138
1139 /* The socket must have it's spinlock held when we get
1140  * here.
1141  *
1142  * We have a potential double-lock case here, so even when
1143  * doing backlog processing we use the BH locking scheme.
1144  * This is because we cannot sleep with the original spinlock
1145  * held.
1146  */
1147 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
1148 {
1149         if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
1150                 TCP_CHECK_TIMER(sk);
1151                 if (tcp_rcv_established(sk, skb, skb->h.th, skb->len))
1152                         goto reset;
1153                 TCP_CHECK_TIMER(sk);
1154                 return 0;
1155         }
1156
1157         if (skb->len < (skb->h.th->doff << 2) || tcp_checksum_complete(skb))
1158                 goto csum_err;
1159
1160         if (sk->sk_state == TCP_LISTEN) {
1161                 struct sock *nsk = tcp_v4_hnd_req(sk, skb);
1162                 if (!nsk)
1163                         goto discard;
1164
1165                 if (nsk != sk) {
1166                         if (tcp_child_process(sk, nsk, skb))
1167                                 goto reset;
1168                         return 0;
1169                 }
1170         }
1171
1172         TCP_CHECK_TIMER(sk);
1173         if (tcp_rcv_state_process(sk, skb, skb->h.th, skb->len))
1174                 goto reset;
1175         TCP_CHECK_TIMER(sk);
1176         return 0;
1177
1178 reset:
1179         tcp_v4_send_reset(skb);
1180 discard:
1181         kfree_skb(skb);
1182         /* Be careful here. If this function gets more complicated and
1183          * gcc suffers from register pressure on the x86, sk (in %ebx)
1184          * might be destroyed here. This current version compiles correctly,
1185          * but you have been warned.
1186          */
1187         return 0;
1188
1189 csum_err:
1190         TCP_INC_STATS_BH(TCP_MIB_INERRS);
1191         goto discard;
1192 }
1193
1194 /*
1195  *      From tcp_input.c
1196  */
1197
1198 int tcp_v4_rcv(struct sk_buff *skb)
1199 {
1200         struct tcphdr *th;
1201         struct sock *sk;
1202         int ret;
1203
1204         if (skb->pkt_type != PACKET_HOST)
1205                 goto discard_it;
1206
1207         /* Count it even if it's bad */
1208         TCP_INC_STATS_BH(TCP_MIB_INSEGS);
1209
1210         if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
1211                 goto discard_it;
1212
1213         th = skb->h.th;
1214
1215         if (th->doff < sizeof(struct tcphdr) / 4)
1216                 goto bad_packet;
1217         if (!pskb_may_pull(skb, th->doff * 4))
1218                 goto discard_it;
1219
1220         /* An explanation is required here, I think.
1221          * Packet length and doff are validated by header prediction,
1222          * provided case of th->doff==0 is elimineted.
1223          * So, we defer the checks. */
1224         if ((skb->ip_summed != CHECKSUM_UNNECESSARY &&
1225              tcp_v4_checksum_init(skb) < 0))
1226                 goto bad_packet;
1227
1228         th = skb->h.th;
1229         TCP_SKB_CB(skb)->seq = ntohl(th->seq);
1230         TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
1231                                     skb->len - th->doff * 4);
1232         TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
1233         TCP_SKB_CB(skb)->when    = 0;
1234         TCP_SKB_CB(skb)->flags   = skb->nh.iph->tos;
1235         TCP_SKB_CB(skb)->sacked  = 0;
1236
1237         sk = __inet_lookup(&tcp_hashinfo, skb->nh.iph->saddr, th->source,
1238                            skb->nh.iph->daddr, ntohs(th->dest),
1239                            inet_iif(skb));
1240
1241         if (!sk)
1242                 goto no_tcp_socket;
1243
1244 process:
1245         if (sk->sk_state == TCP_TIME_WAIT)
1246                 goto do_time_wait;
1247
1248         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
1249                 goto discard_and_relse;
1250
1251         if (sk_filter(sk, skb, 0))
1252                 goto discard_and_relse;
1253
1254         skb->dev = NULL;
1255
1256         bh_lock_sock(sk);
1257         ret = 0;
1258         if (!sock_owned_by_user(sk)) {
1259                 if (!tcp_prequeue(sk, skb))
1260                         ret = tcp_v4_do_rcv(sk, skb);
1261         } else
1262                 sk_add_backlog(sk, skb);
1263         bh_unlock_sock(sk);
1264
1265         sock_put(sk);
1266
1267         return ret;
1268
1269 no_tcp_socket:
1270         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
1271                 goto discard_it;
1272
1273         if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1274 bad_packet:
1275                 TCP_INC_STATS_BH(TCP_MIB_INERRS);
1276         } else {
1277                 tcp_v4_send_reset(skb);
1278         }
1279
1280 discard_it:
1281         /* Discard frame. */
1282         kfree_skb(skb);
1283         return 0;
1284
1285 discard_and_relse:
1286         sock_put(sk);
1287         goto discard_it;
1288
1289 do_time_wait:
1290         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1291                 inet_twsk_put((struct inet_timewait_sock *) sk);
1292                 goto discard_it;
1293         }
1294
1295         if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1296                 TCP_INC_STATS_BH(TCP_MIB_INERRS);
1297                 inet_twsk_put((struct inet_timewait_sock *) sk);
1298                 goto discard_it;
1299         }
1300         switch (tcp_timewait_state_process((struct inet_timewait_sock *)sk,
1301                                            skb, th)) {
1302         case TCP_TW_SYN: {
1303                 struct sock *sk2 = inet_lookup_listener(&tcp_hashinfo,
1304                                                         skb->nh.iph->daddr,
1305                                                         ntohs(th->dest),
1306                                                         inet_iif(skb));
1307                 if (sk2) {
1308                         inet_twsk_deschedule((struct inet_timewait_sock *)sk,
1309                                              &tcp_death_row);
1310                         inet_twsk_put((struct inet_timewait_sock *)sk);
1311                         sk = sk2;
1312                         goto process;
1313                 }
1314                 /* Fall through to ACK */
1315         }
1316         case TCP_TW_ACK:
1317                 tcp_v4_timewait_ack(sk, skb);
1318                 break;
1319         case TCP_TW_RST:
1320                 goto no_tcp_socket;
1321         case TCP_TW_SUCCESS:;
1322         }
1323         goto discard_it;
1324 }
1325
1326 static void v4_addr2sockaddr(struct sock *sk, struct sockaddr * uaddr)
1327 {
1328         struct sockaddr_in *sin = (struct sockaddr_in *) uaddr;
1329         struct inet_sock *inet = inet_sk(sk);
1330
1331         sin->sin_family         = AF_INET;
1332         sin->sin_addr.s_addr    = inet->daddr;
1333         sin->sin_port           = inet->dport;
1334 }
1335
1336 /* VJ's idea. Save last timestamp seen from this destination
1337  * and hold it at least for normal timewait interval to use for duplicate
1338  * segment detection in subsequent connections, before they enter synchronized
1339  * state.
1340  */
1341
1342 int tcp_v4_remember_stamp(struct sock *sk)
1343 {
1344         struct inet_sock *inet = inet_sk(sk);
1345         struct tcp_sock *tp = tcp_sk(sk);
1346         struct rtable *rt = (struct rtable *)__sk_dst_get(sk);
1347         struct inet_peer *peer = NULL;
1348         int release_it = 0;
1349
1350         if (!rt || rt->rt_dst != inet->daddr) {
1351                 peer = inet_getpeer(inet->daddr, 1);
1352                 release_it = 1;
1353         } else {
1354                 if (!rt->peer)
1355                         rt_bind_peer(rt, 1);
1356                 peer = rt->peer;
1357         }
1358
1359         if (peer) {
1360                 if ((s32)(peer->tcp_ts - tp->rx_opt.ts_recent) <= 0 ||
1361                     (peer->tcp_ts_stamp + TCP_PAWS_MSL < xtime.tv_sec &&
1362                      peer->tcp_ts_stamp <= tp->rx_opt.ts_recent_stamp)) {
1363                         peer->tcp_ts_stamp = tp->rx_opt.ts_recent_stamp;
1364                         peer->tcp_ts = tp->rx_opt.ts_recent;
1365                 }
1366                 if (release_it)
1367                         inet_putpeer(peer);
1368                 return 1;
1369         }
1370
1371         return 0;
1372 }
1373
1374 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw)
1375 {
1376         struct inet_peer *peer = inet_getpeer(tw->tw_daddr, 1);
1377
1378         if (peer) {
1379                 const struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
1380
1381                 if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 ||
1382                     (peer->tcp_ts_stamp + TCP_PAWS_MSL < xtime.tv_sec &&
1383                      peer->tcp_ts_stamp <= tcptw->tw_ts_recent_stamp)) {
1384                         peer->tcp_ts_stamp = tcptw->tw_ts_recent_stamp;
1385                         peer->tcp_ts       = tcptw->tw_ts_recent;
1386                 }
1387                 inet_putpeer(peer);
1388                 return 1;
1389         }
1390
1391         return 0;
1392 }
1393
1394 struct tcp_func ipv4_specific = {
1395         .queue_xmit     =       ip_queue_xmit,
1396         .send_check     =       tcp_v4_send_check,
1397         .rebuild_header =       inet_sk_rebuild_header,
1398         .conn_request   =       tcp_v4_conn_request,
1399         .syn_recv_sock  =       tcp_v4_syn_recv_sock,
1400         .remember_stamp =       tcp_v4_remember_stamp,
1401         .net_header_len =       sizeof(struct iphdr),
1402         .setsockopt     =       ip_setsockopt,
1403         .getsockopt     =       ip_getsockopt,
1404         .addr2sockaddr  =       v4_addr2sockaddr,
1405         .sockaddr_len   =       sizeof(struct sockaddr_in),
1406 };
1407
1408 /* NOTE: A lot of things set to zero explicitly by call to
1409  *       sk_alloc() so need not be done here.
1410  */
1411 static int tcp_v4_init_sock(struct sock *sk)
1412 {
1413         struct inet_connection_sock *icsk = inet_csk(sk);
1414         struct tcp_sock *tp = tcp_sk(sk);
1415
1416         skb_queue_head_init(&tp->out_of_order_queue);
1417         tcp_init_xmit_timers(sk);
1418         tcp_prequeue_init(tp);
1419
1420         icsk->icsk_rto = TCP_TIMEOUT_INIT;
1421         tp->mdev = TCP_TIMEOUT_INIT;
1422
1423         /* So many TCP implementations out there (incorrectly) count the
1424          * initial SYN frame in their delayed-ACK and congestion control
1425          * algorithms that we must have the following bandaid to talk
1426          * efficiently to them.  -DaveM
1427          */
1428         tp->snd_cwnd = 2;
1429
1430         /* See draft-stevens-tcpca-spec-01 for discussion of the
1431          * initialization of these values.
1432          */
1433         tp->snd_ssthresh = 0x7fffffff;  /* Infinity */
1434         tp->snd_cwnd_clamp = ~0;
1435         tp->mss_cache = 536;
1436
1437         tp->reordering = sysctl_tcp_reordering;
1438         icsk->icsk_ca_ops = &tcp_init_congestion_ops;
1439
1440         sk->sk_state = TCP_CLOSE;
1441
1442         sk->sk_write_space = sk_stream_write_space;
1443         sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1444
1445         tp->af_specific = &ipv4_specific;
1446
1447         sk->sk_sndbuf = sysctl_tcp_wmem[1];
1448         sk->sk_rcvbuf = sysctl_tcp_rmem[1];
1449
1450         atomic_inc(&tcp_sockets_allocated);
1451
1452         return 0;
1453 }
1454
1455 int tcp_v4_destroy_sock(struct sock *sk)
1456 {
1457         struct tcp_sock *tp = tcp_sk(sk);
1458
1459         tcp_clear_xmit_timers(sk);
1460
1461         tcp_cleanup_congestion_control(sk);
1462
1463         /* Cleanup up the write buffer. */
1464         sk_stream_writequeue_purge(sk);
1465
1466         /* Cleans up our, hopefully empty, out_of_order_queue. */
1467         __skb_queue_purge(&tp->out_of_order_queue);
1468
1469         /* Clean prequeue, it must be empty really */
1470         __skb_queue_purge(&tp->ucopy.prequeue);
1471
1472         /* Clean up a referenced TCP bind bucket. */
1473         if (inet_csk(sk)->icsk_bind_hash)
1474                 inet_put_port(&tcp_hashinfo, sk);
1475
1476         /*
1477          * If sendmsg cached page exists, toss it.
1478          */
1479         if (sk->sk_sndmsg_page) {
1480                 __free_page(sk->sk_sndmsg_page);
1481                 sk->sk_sndmsg_page = NULL;
1482         }
1483
1484         atomic_dec(&tcp_sockets_allocated);
1485
1486         return 0;
1487 }
1488
1489 EXPORT_SYMBOL(tcp_v4_destroy_sock);
1490
1491 #ifdef CONFIG_PROC_FS
1492 /* Proc filesystem TCP sock list dumping. */
1493
1494 static inline struct inet_timewait_sock *tw_head(struct hlist_head *head)
1495 {
1496         return hlist_empty(head) ? NULL :
1497                 list_entry(head->first, struct inet_timewait_sock, tw_node);
1498 }
1499
1500 static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw)
1501 {
1502         return tw->tw_node.next ?
1503                 hlist_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL;
1504 }
1505
1506 static void *listening_get_next(struct seq_file *seq, void *cur)
1507 {
1508         struct inet_connection_sock *icsk;
1509         struct hlist_node *node;
1510         struct sock *sk = cur;
1511         struct tcp_iter_state* st = seq->private;
1512
1513         if (!sk) {
1514                 st->bucket = 0;
1515                 sk = sk_head(&tcp_hashinfo.listening_hash[0]);
1516                 goto get_sk;
1517         }
1518
1519         ++st->num;
1520
1521         if (st->state == TCP_SEQ_STATE_OPENREQ) {
1522                 struct request_sock *req = cur;
1523
1524                 icsk = inet_csk(st->syn_wait_sk);
1525                 req = req->dl_next;
1526                 while (1) {
1527                         while (req) {
1528                                 if (req->rsk_ops->family == st->family) {
1529                                         cur = req;
1530                                         goto out;
1531                                 }
1532                                 req = req->dl_next;
1533                         }
1534                         if (++st->sbucket >= TCP_SYNQ_HSIZE)
1535                                 break;
1536 get_req:
1537                         req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];
1538                 }
1539                 sk        = sk_next(st->syn_wait_sk);
1540                 st->state = TCP_SEQ_STATE_LISTENING;
1541                 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1542         } else {
1543                 icsk = inet_csk(sk);
1544                 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1545                 if (reqsk_queue_len(&icsk->icsk_accept_queue))
1546                         goto start_req;
1547                 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1548                 sk = sk_next(sk);
1549         }
1550 get_sk:
1551         sk_for_each_from(sk, node) {
1552                 if (sk->sk_family == st->family) {
1553                         cur = sk;
1554                         goto out;
1555                 }
1556                 icsk = inet_csk(sk);
1557                 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1558                 if (reqsk_queue_len(&icsk->icsk_accept_queue)) {
1559 start_req:
1560                         st->uid         = sock_i_uid(sk);
1561                         st->syn_wait_sk = sk;
1562                         st->state       = TCP_SEQ_STATE_OPENREQ;
1563                         st->sbucket     = 0;
1564                         goto get_req;
1565                 }
1566                 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1567         }
1568         if (++st->bucket < INET_LHTABLE_SIZE) {
1569                 sk = sk_head(&tcp_hashinfo.listening_hash[st->bucket]);
1570                 goto get_sk;
1571         }
1572         cur = NULL;
1573 out:
1574         return cur;
1575 }
1576
1577 static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
1578 {
1579         void *rc = listening_get_next(seq, NULL);
1580
1581         while (rc && *pos) {
1582                 rc = listening_get_next(seq, rc);
1583                 --*pos;
1584         }
1585         return rc;
1586 }
1587
1588 static void *established_get_first(struct seq_file *seq)
1589 {
1590         struct tcp_iter_state* st = seq->private;
1591         void *rc = NULL;
1592
1593         for (st->bucket = 0; st->bucket < tcp_hashinfo.ehash_size; ++st->bucket) {
1594                 struct sock *sk;
1595                 struct hlist_node *node;
1596                 struct inet_timewait_sock *tw;
1597
1598                 /* We can reschedule _before_ having picked the target: */
1599                 cond_resched_softirq();
1600
1601                 read_lock(&tcp_hashinfo.ehash[st->bucket].lock);
1602                 sk_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
1603                         if (sk->sk_family != st->family) {
1604                                 continue;
1605                         }
1606                         rc = sk;
1607                         goto out;
1608                 }
1609                 st->state = TCP_SEQ_STATE_TIME_WAIT;
1610                 inet_twsk_for_each(tw, node,
1611                                    &tcp_hashinfo.ehash[st->bucket + tcp_hashinfo.ehash_size].chain) {
1612                         if (tw->tw_family != st->family) {
1613                                 continue;
1614                         }
1615                         rc = tw;
1616                         goto out;
1617                 }
1618                 read_unlock(&tcp_hashinfo.ehash[st->bucket].lock);
1619                 st->state = TCP_SEQ_STATE_ESTABLISHED;
1620         }
1621 out:
1622         return rc;
1623 }
1624
1625 static void *established_get_next(struct seq_file *seq, void *cur)
1626 {
1627         struct sock *sk = cur;
1628         struct inet_timewait_sock *tw;
1629         struct hlist_node *node;
1630         struct tcp_iter_state* st = seq->private;
1631
1632         ++st->num;
1633
1634         if (st->state == TCP_SEQ_STATE_TIME_WAIT) {
1635                 tw = cur;
1636                 tw = tw_next(tw);
1637 get_tw:
1638                 while (tw && tw->tw_family != st->family) {
1639                         tw = tw_next(tw);
1640                 }
1641                 if (tw) {
1642                         cur = tw;
1643                         goto out;
1644                 }
1645                 read_unlock(&tcp_hashinfo.ehash[st->bucket].lock);
1646                 st->state = TCP_SEQ_STATE_ESTABLISHED;
1647
1648                 /* We can reschedule between buckets: */
1649                 cond_resched_softirq();
1650
1651                 if (++st->bucket < tcp_hashinfo.ehash_size) {
1652                         read_lock(&tcp_hashinfo.ehash[st->bucket].lock);
1653                         sk = sk_head(&tcp_hashinfo.ehash[st->bucket].chain);
1654                 } else {
1655                         cur = NULL;
1656                         goto out;
1657                 }
1658         } else
1659                 sk = sk_next(sk);
1660
1661         sk_for_each_from(sk, node) {
1662                 if (sk->sk_family == st->family)
1663                         goto found;
1664         }
1665
1666         st->state = TCP_SEQ_STATE_TIME_WAIT;
1667         tw = tw_head(&tcp_hashinfo.ehash[st->bucket + tcp_hashinfo.ehash_size].chain);
1668         goto get_tw;
1669 found:
1670         cur = sk;
1671 out:
1672         return cur;
1673 }
1674
1675 static void *established_get_idx(struct seq_file *seq, loff_t pos)
1676 {
1677         void *rc = established_get_first(seq);
1678
1679         while (rc && pos) {
1680                 rc = established_get_next(seq, rc);
1681                 --pos;
1682         }
1683         return rc;
1684 }
1685
1686 static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
1687 {
1688         void *rc;
1689         struct tcp_iter_state* st = seq->private;
1690
1691         inet_listen_lock(&tcp_hashinfo);
1692         st->state = TCP_SEQ_STATE_LISTENING;
1693         rc        = listening_get_idx(seq, &pos);
1694
1695         if (!rc) {
1696                 inet_listen_unlock(&tcp_hashinfo);
1697                 local_bh_disable();
1698                 st->state = TCP_SEQ_STATE_ESTABLISHED;
1699                 rc        = established_get_idx(seq, pos);
1700         }
1701
1702         return rc;
1703 }
1704
1705 static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
1706 {
1707         struct tcp_iter_state* st = seq->private;
1708         st->state = TCP_SEQ_STATE_LISTENING;
1709         st->num = 0;
1710         return *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
1711 }
1712
1713 static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1714 {
1715         void *rc = NULL;
1716         struct tcp_iter_state* st;
1717
1718         if (v == SEQ_START_TOKEN) {
1719                 rc = tcp_get_idx(seq, 0);
1720                 goto out;
1721         }
1722         st = seq->private;
1723
1724         switch (st->state) {
1725         case TCP_SEQ_STATE_OPENREQ:
1726         case TCP_SEQ_STATE_LISTENING:
1727                 rc = listening_get_next(seq, v);
1728                 if (!rc) {
1729                         inet_listen_unlock(&tcp_hashinfo);
1730                         local_bh_disable();
1731                         st->state = TCP_SEQ_STATE_ESTABLISHED;
1732                         rc        = established_get_first(seq);
1733                 }
1734                 break;
1735         case TCP_SEQ_STATE_ESTABLISHED:
1736         case TCP_SEQ_STATE_TIME_WAIT:
1737                 rc = established_get_next(seq, v);
1738                 break;
1739         }
1740 out:
1741         ++*pos;
1742         return rc;
1743 }
1744
1745 static void tcp_seq_stop(struct seq_file *seq, void *v)
1746 {
1747         struct tcp_iter_state* st = seq->private;
1748
1749         switch (st->state) {
1750         case TCP_SEQ_STATE_OPENREQ:
1751                 if (v) {
1752                         struct inet_connection_sock *icsk = inet_csk(st->syn_wait_sk);
1753                         read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1754                 }
1755         case TCP_SEQ_STATE_LISTENING:
1756                 if (v != SEQ_START_TOKEN)
1757                         inet_listen_unlock(&tcp_hashinfo);
1758                 break;
1759         case TCP_SEQ_STATE_TIME_WAIT:
1760         case TCP_SEQ_STATE_ESTABLISHED:
1761                 if (v)
1762                         read_unlock(&tcp_hashinfo.ehash[st->bucket].lock);
1763                 local_bh_enable();
1764                 break;
1765         }
1766 }
1767
1768 static int tcp_seq_open(struct inode *inode, struct file *file)
1769 {
1770         struct tcp_seq_afinfo *afinfo = PDE(inode)->data;
1771         struct seq_file *seq;
1772         struct tcp_iter_state *s;
1773         int rc;
1774
1775         if (unlikely(afinfo == NULL))
1776                 return -EINVAL;
1777
1778         s = kmalloc(sizeof(*s), GFP_KERNEL);
1779         if (!s)
1780                 return -ENOMEM;
1781         memset(s, 0, sizeof(*s));
1782         s->family               = afinfo->family;
1783         s->seq_ops.start        = tcp_seq_start;
1784         s->seq_ops.next         = tcp_seq_next;
1785         s->seq_ops.show         = afinfo->seq_show;
1786         s->seq_ops.stop         = tcp_seq_stop;
1787
1788         rc = seq_open(file, &s->seq_ops);
1789         if (rc)
1790                 goto out_kfree;
1791         seq          = file->private_data;
1792         seq->private = s;
1793 out:
1794         return rc;
1795 out_kfree:
1796         kfree(s);
1797         goto out;
1798 }
1799
1800 int tcp_proc_register(struct tcp_seq_afinfo *afinfo)
1801 {
1802         int rc = 0;
1803         struct proc_dir_entry *p;
1804
1805         if (!afinfo)
1806                 return -EINVAL;
1807         afinfo->seq_fops->owner         = afinfo->owner;
1808         afinfo->seq_fops->open          = tcp_seq_open;
1809         afinfo->seq_fops->read          = seq_read;
1810         afinfo->seq_fops->llseek        = seq_lseek;
1811         afinfo->seq_fops->release       = seq_release_private;
1812
1813         p = proc_net_fops_create(afinfo->name, S_IRUGO, afinfo->seq_fops);
1814         if (p)
1815                 p->data = afinfo;
1816         else
1817                 rc = -ENOMEM;
1818         return rc;
1819 }
1820
1821 void tcp_proc_unregister(struct tcp_seq_afinfo *afinfo)
1822 {
1823         if (!afinfo)
1824                 return;
1825         proc_net_remove(afinfo->name);
1826         memset(afinfo->seq_fops, 0, sizeof(*afinfo->seq_fops));
1827 }
1828
1829 static void get_openreq4(struct sock *sk, struct request_sock *req,
1830                          char *tmpbuf, int i, int uid)
1831 {
1832         const struct inet_request_sock *ireq = inet_rsk(req);
1833         int ttd = req->expires - jiffies;
1834
1835         sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X"
1836                 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %p",
1837                 i,
1838                 ireq->loc_addr,
1839                 ntohs(inet_sk(sk)->sport),
1840                 ireq->rmt_addr,
1841                 ntohs(ireq->rmt_port),
1842                 TCP_SYN_RECV,
1843                 0, 0, /* could print option size, but that is af dependent. */
1844                 1,    /* timers active (only the expire timer) */
1845                 jiffies_to_clock_t(ttd),
1846                 req->retrans,
1847                 uid,
1848                 0,  /* non standard timer */
1849                 0, /* open_requests have no inode */
1850                 atomic_read(&sk->sk_refcnt),
1851                 req);
1852 }
1853
1854 static void get_tcp4_sock(struct sock *sp, char *tmpbuf, int i)
1855 {
1856         int timer_active;
1857         unsigned long timer_expires;
1858         struct tcp_sock *tp = tcp_sk(sp);
1859         const struct inet_connection_sock *icsk = inet_csk(sp);
1860         struct inet_sock *inet = inet_sk(sp);
1861         unsigned int dest = inet->daddr;
1862         unsigned int src = inet->rcv_saddr;
1863         __u16 destp = ntohs(inet->dport);
1864         __u16 srcp = ntohs(inet->sport);
1865
1866         if (icsk->icsk_pending == ICSK_TIME_RETRANS) {
1867                 timer_active    = 1;
1868                 timer_expires   = icsk->icsk_timeout;
1869         } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
1870                 timer_active    = 4;
1871                 timer_expires   = icsk->icsk_timeout;
1872         } else if (timer_pending(&sp->sk_timer)) {
1873                 timer_active    = 2;
1874                 timer_expires   = sp->sk_timer.expires;
1875         } else {
1876                 timer_active    = 0;
1877                 timer_expires = jiffies;
1878         }
1879
1880         sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
1881                         "%08X %5d %8d %lu %d %p %u %u %u %u %d",
1882                 i, src, srcp, dest, destp, sp->sk_state,
1883                 tp->write_seq - tp->snd_una, tp->rcv_nxt - tp->copied_seq,
1884                 timer_active,
1885                 jiffies_to_clock_t(timer_expires - jiffies),
1886                 icsk->icsk_retransmits,
1887                 sock_i_uid(sp),
1888                 icsk->icsk_probes_out,
1889                 sock_i_ino(sp),
1890                 atomic_read(&sp->sk_refcnt), sp,
1891                 icsk->icsk_rto,
1892                 icsk->icsk_ack.ato,
1893                 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
1894                 tp->snd_cwnd,
1895                 tp->snd_ssthresh >= 0xFFFF ? -1 : tp->snd_ssthresh);
1896 }
1897
1898 static void get_timewait4_sock(struct inet_timewait_sock *tw, char *tmpbuf, int i)
1899 {
1900         unsigned int dest, src;
1901         __u16 destp, srcp;
1902         int ttd = tw->tw_ttd - jiffies;
1903
1904         if (ttd < 0)
1905                 ttd = 0;
1906
1907         dest  = tw->tw_daddr;
1908         src   = tw->tw_rcv_saddr;
1909         destp = ntohs(tw->tw_dport);
1910         srcp  = ntohs(tw->tw_sport);
1911
1912         sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X"
1913                 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %p",
1914                 i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
1915                 3, jiffies_to_clock_t(ttd), 0, 0, 0, 0,
1916                 atomic_read(&tw->tw_refcnt), tw);
1917 }
1918
1919 #define TMPSZ 150
1920
1921 static int tcp4_seq_show(struct seq_file *seq, void *v)
1922 {
1923         struct tcp_iter_state* st;
1924         char tmpbuf[TMPSZ + 1];
1925
1926         if (v == SEQ_START_TOKEN) {
1927                 seq_printf(seq, "%-*s\n", TMPSZ - 1,
1928                            "  sl  local_address rem_address   st tx_queue "
1929                            "rx_queue tr tm->when retrnsmt   uid  timeout "
1930                            "inode");
1931                 goto out;
1932         }
1933         st = seq->private;
1934
1935         switch (st->state) {
1936         case TCP_SEQ_STATE_LISTENING:
1937         case TCP_SEQ_STATE_ESTABLISHED:
1938                 get_tcp4_sock(v, tmpbuf, st->num);
1939                 break;
1940         case TCP_SEQ_STATE_OPENREQ:
1941                 get_openreq4(st->syn_wait_sk, v, tmpbuf, st->num, st->uid);
1942                 break;
1943         case TCP_SEQ_STATE_TIME_WAIT:
1944                 get_timewait4_sock(v, tmpbuf, st->num);
1945                 break;
1946         }
1947         seq_printf(seq, "%-*s\n", TMPSZ - 1, tmpbuf);
1948 out:
1949         return 0;
1950 }
1951
1952 static struct file_operations tcp4_seq_fops;
1953 static struct tcp_seq_afinfo tcp4_seq_afinfo = {
1954         .owner          = THIS_MODULE,
1955         .name           = "tcp",
1956         .family         = AF_INET,
1957         .seq_show       = tcp4_seq_show,
1958         .seq_fops       = &tcp4_seq_fops,
1959 };
1960
1961 int __init tcp4_proc_init(void)
1962 {
1963         return tcp_proc_register(&tcp4_seq_afinfo);
1964 }
1965
1966 void tcp4_proc_exit(void)
1967 {
1968         tcp_proc_unregister(&tcp4_seq_afinfo);
1969 }
1970 #endif /* CONFIG_PROC_FS */
1971
1972 struct proto tcp_prot = {
1973         .name                   = "TCP",
1974         .owner                  = THIS_MODULE,
1975         .close                  = tcp_close,
1976         .connect                = tcp_v4_connect,
1977         .disconnect             = tcp_disconnect,
1978         .accept                 = inet_csk_accept,
1979         .ioctl                  = tcp_ioctl,
1980         .init                   = tcp_v4_init_sock,
1981         .destroy                = tcp_v4_destroy_sock,
1982         .shutdown               = tcp_shutdown,
1983         .setsockopt             = tcp_setsockopt,
1984         .getsockopt             = tcp_getsockopt,
1985         .sendmsg                = tcp_sendmsg,
1986         .recvmsg                = tcp_recvmsg,
1987         .backlog_rcv            = tcp_v4_do_rcv,
1988         .hash                   = tcp_v4_hash,
1989         .unhash                 = tcp_unhash,
1990         .get_port               = tcp_v4_get_port,
1991         .enter_memory_pressure  = tcp_enter_memory_pressure,
1992         .sockets_allocated      = &tcp_sockets_allocated,
1993         .orphan_count           = &tcp_orphan_count,
1994         .memory_allocated       = &tcp_memory_allocated,
1995         .memory_pressure        = &tcp_memory_pressure,
1996         .sysctl_mem             = sysctl_tcp_mem,
1997         .sysctl_wmem            = sysctl_tcp_wmem,
1998         .sysctl_rmem            = sysctl_tcp_rmem,
1999         .max_header             = MAX_TCP_HEADER,
2000         .obj_size               = sizeof(struct tcp_sock),
2001         .twsk_obj_size          = sizeof(struct tcp_timewait_sock),
2002         .rsk_prot               = &tcp_request_sock_ops,
2003 };
2004
2005
2006
2007 void __init tcp_v4_init(struct net_proto_family *ops)
2008 {
2009         int err = sock_create_kern(PF_INET, SOCK_RAW, IPPROTO_TCP, &tcp_socket);
2010         if (err < 0)
2011                 panic("Failed to create the TCP control socket.\n");
2012         tcp_socket->sk->sk_allocation   = GFP_ATOMIC;
2013         inet_sk(tcp_socket->sk)->uc_ttl = -1;
2014
2015         /* Unhash it so that IP input processing does not even
2016          * see it, we do not wish this socket to see incoming
2017          * packets.
2018          */
2019         tcp_socket->sk->sk_prot->unhash(tcp_socket->sk);
2020 }
2021
2022 EXPORT_SYMBOL(ipv4_specific);
2023 EXPORT_SYMBOL(inet_bind_bucket_create);
2024 EXPORT_SYMBOL(tcp_hashinfo);
2025 EXPORT_SYMBOL(tcp_prot);
2026 EXPORT_SYMBOL(tcp_unhash);
2027 EXPORT_SYMBOL(tcp_v4_conn_request);
2028 EXPORT_SYMBOL(tcp_v4_connect);
2029 EXPORT_SYMBOL(tcp_v4_do_rcv);
2030 EXPORT_SYMBOL(tcp_v4_remember_stamp);
2031 EXPORT_SYMBOL(tcp_v4_send_check);
2032 EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
2033
2034 #ifdef CONFIG_PROC_FS
2035 EXPORT_SYMBOL(tcp_proc_register);
2036 EXPORT_SYMBOL(tcp_proc_unregister);
2037 #endif
2038 EXPORT_SYMBOL(sysctl_local_port_range);
2039 EXPORT_SYMBOL(sysctl_tcp_low_latency);
2040 EXPORT_SYMBOL(sysctl_tcp_tw_reuse);
2041