linux/net/ipv4/tcp.c
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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 * Authors:     Ross Biro
   9 *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  10 *              Mark Evans, <evansmp@uhura.aston.ac.uk>
  11 *              Corey Minyard <wf-rch!minyard@relay.EU.net>
  12 *              Florian La Roche, <flla@stud.uni-sb.de>
  13 *              Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
  14 *              Linus Torvalds, <torvalds@cs.helsinki.fi>
  15 *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  16 *              Matthew Dillon, <dillon@apollo.west.oic.com>
  17 *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
  18 *              Jorge Cwik, <jorge@laser.satlink.net>
  19 *
  20 * Fixes:
  21 *              Alan Cox        :       Numerous verify_area() calls
  22 *              Alan Cox        :       Set the ACK bit on a reset
  23 *              Alan Cox        :       Stopped it crashing if it closed while
  24 *                                      sk->inuse=1 and was trying to connect
  25 *                                      (tcp_err()).
  26 *              Alan Cox        :       All icmp error handling was broken
  27 *                                      pointers passed where wrong and the
  28 *                                      socket was looked up backwards. Nobody
  29 *                                      tested any icmp error code obviously.
  30 *              Alan Cox        :       tcp_err() now handled properly. It
  31 *                                      wakes people on errors. poll
  32 *                                      behaves and the icmp error race
  33 *                                      has gone by moving it into sock.c
  34 *              Alan Cox        :       tcp_send_reset() fixed to work for
  35 *                                      everything not just packets for
  36 *                                      unknown sockets.
  37 *              Alan Cox        :       tcp option processing.
  38 *              Alan Cox        :       Reset tweaked (still not 100%) [Had
  39 *                                      syn rule wrong]
  40 *              Herp Rosmanith  :       More reset fixes
  41 *              Alan Cox        :       No longer acks invalid rst frames.
  42 *                                      Acking any kind of RST is right out.
  43 *              Alan Cox        :       Sets an ignore me flag on an rst
  44 *                                      receive otherwise odd bits of prattle
  45 *                                      escape still
  46 *              Alan Cox        :       Fixed another acking RST frame bug.
  47 *                                      Should stop LAN workplace lockups.
  48 *              Alan Cox        :       Some tidyups using the new skb list
  49 *                                      facilities
  50 *              Alan Cox        :       sk->keepopen now seems to work
  51 *              Alan Cox        :       Pulls options out correctly on accepts
  52 *              Alan Cox        :       Fixed assorted sk->rqueue->next errors
  53 *              Alan Cox        :       PSH doesn't end a TCP read. Switched a
  54 *                                      bit to skb ops.
  55 *              Alan Cox        :       Tidied tcp_data to avoid a potential
  56 *                                      nasty.
  57 *              Alan Cox        :       Added some better commenting, as the
  58 *                                      tcp is hard to follow
  59 *              Alan Cox        :       Removed incorrect check for 20 * psh
  60 *      Michael O'Reilly        :       ack < copied bug fix.
  61 *      Johannes Stille         :       Misc tcp fixes (not all in yet).
  62 *              Alan Cox        :       FIN with no memory -> CRASH
  63 *              Alan Cox        :       Added socket option proto entries.
  64 *                                      Also added awareness of them to accept.
  65 *              Alan Cox        :       Added TCP options (SOL_TCP)
  66 *              Alan Cox        :       Switched wakeup calls to callbacks,
  67 *                                      so the kernel can layer network
  68 *                                      sockets.
  69 *              Alan Cox        :       Use ip_tos/ip_ttl settings.
  70 *              Alan Cox        :       Handle FIN (more) properly (we hope).
  71 *              Alan Cox        :       RST frames sent on unsynchronised
  72 *                                      state ack error.
  73 *              Alan Cox        :       Put in missing check for SYN bit.
  74 *              Alan Cox        :       Added tcp_select_window() aka NET2E
  75 *                                      window non shrink trick.
  76 *              Alan Cox        :       Added a couple of small NET2E timer
  77 *                                      fixes
  78 *              Charles Hedrick :       TCP fixes
  79 *              Toomas Tamm     :       TCP window fixes
  80 *              Alan Cox        :       Small URG fix to rlogin ^C ack fight
  81 *              Charles Hedrick :       Rewrote most of it to actually work
  82 *              Linus           :       Rewrote tcp_read() and URG handling
  83 *                                      completely
  84 *              Gerhard Koerting:       Fixed some missing timer handling
  85 *              Matthew Dillon  :       Reworked TCP machine states as per RFC
  86 *              Gerhard Koerting:       PC/TCP workarounds
  87 *              Adam Caldwell   :       Assorted timer/timing errors
  88 *              Matthew Dillon  :       Fixed another RST bug
  89 *              Alan Cox        :       Move to kernel side addressing changes.
  90 *              Alan Cox        :       Beginning work on TCP fastpathing
  91 *                                      (not yet usable)
  92 *              Arnt Gulbrandsen:       Turbocharged tcp_check() routine.
  93 *              Alan Cox        :       TCP fast path debugging
  94 *              Alan Cox        :       Window clamping
  95 *              Michael Riepe   :       Bug in tcp_check()
  96 *              Matt Dillon     :       More TCP improvements and RST bug fixes
  97 *              Matt Dillon     :       Yet more small nasties remove from the
  98 *                                      TCP code (Be very nice to this man if
  99 *                                      tcp finally works 100%) 8)
 100 *              Alan Cox        :       BSD accept semantics.
 101 *              Alan Cox        :       Reset on closedown bug.
 102 *      Peter De Schrijver      :       ENOTCONN check missing in tcp_sendto().
 103 *              Michael Pall    :       Handle poll() after URG properly in
 104 *                                      all cases.
 105 *              Michael Pall    :       Undo the last fix in tcp_read_urg()
 106 *                                      (multi URG PUSH broke rlogin).
 107 *              Michael Pall    :       Fix the multi URG PUSH problem in
 108 *                                      tcp_readable(), poll() after URG
 109 *                                      works now.
 110 *              Michael Pall    :       recv(...,MSG_OOB) never blocks in the
 111 *                                      BSD api.
 112 *              Alan Cox        :       Changed the semantics of sk->socket to
 113 *                                      fix a race and a signal problem with
 114 *                                      accept() and async I/O.
 115 *              Alan Cox        :       Relaxed the rules on tcp_sendto().
 116 *              Yury Shevchuk   :       Really fixed accept() blocking problem.
 117 *              Craig I. Hagan  :       Allow for BSD compatible TIME_WAIT for
 118 *                                      clients/servers which listen in on
 119 *                                      fixed ports.
 120 *              Alan Cox        :       Cleaned the above up and shrank it to
 121 *                                      a sensible code size.
 122 *              Alan Cox        :       Self connect lockup fix.
 123 *              Alan Cox        :       No connect to multicast.
 124 *              Ross Biro       :       Close unaccepted children on master
 125 *                                      socket close.
 126 *              Alan Cox        :       Reset tracing code.
 127 *              Alan Cox        :       Spurious resets on shutdown.
 128 *              Alan Cox        :       Giant 15 minute/60 second timer error
 129 *              Alan Cox        :       Small whoops in polling before an
 130 *                                      accept.
 131 *              Alan Cox        :       Kept the state trace facility since
 132 *                                      it's handy for debugging.
 133 *              Alan Cox        :       More reset handler fixes.
 134 *              Alan Cox        :       Started rewriting the code based on
 135 *                                      the RFC's for other useful protocol
 136 *                                      references see: Comer, KA9Q NOS, and
 137 *                                      for a reference on the difference
 138 *                                      between specifications and how BSD
 139 *                                      works see the 4.4lite source.
 140 *              A.N.Kuznetsov   :       Don't time wait on completion of tidy
 141 *                                      close.
 142 *              Linus Torvalds  :       Fin/Shutdown & copied_seq changes.
 143 *              Linus Torvalds  :       Fixed BSD port reuse to work first syn
 144 *              Alan Cox        :       Reimplemented timers as per the RFC
 145 *                                      and using multiple timers for sanity.
 146 *              Alan Cox        :       Small bug fixes, and a lot of new
 147 *                                      comments.
 148 *              Alan Cox        :       Fixed dual reader crash by locking
 149 *                                      the buffers (much like datagram.c)
 150 *              Alan Cox        :       Fixed stuck sockets in probe. A probe
 151 *                                      now gets fed up of retrying without
 152 *                                      (even a no space) answer.
 153 *              Alan Cox        :       Extracted closing code better
 154 *              Alan Cox        :       Fixed the closing state machine to
 155 *                                      resemble the RFC.
 156 *              Alan Cox        :       More 'per spec' fixes.
 157 *              Jorge Cwik      :       Even faster checksumming.
 158 *              Alan Cox        :       tcp_data() doesn't ack illegal PSH
 159 *                                      only frames. At least one pc tcp stack
 160 *                                      generates them.
 161 *              Alan Cox        :       Cache last socket.
 162 *              Alan Cox        :       Per route irtt.
 163 *              Matt Day        :       poll()->select() match BSD precisely on error
 164 *              Alan Cox        :       New buffers
 165 *              Marc Tamsky     :       Various sk->prot->retransmits and
 166 *                                      sk->retransmits misupdating fixed.
 167 *                                      Fixed tcp_write_timeout: stuck close,
 168 *                                      and TCP syn retries gets used now.
 169 *              Mark Yarvis     :       In tcp_read_wakeup(), don't send an
 170 *                                      ack if state is TCP_CLOSED.
 171 *              Alan Cox        :       Look up device on a retransmit - routes may
 172 *                                      change. Doesn't yet cope with MSS shrink right
 173 *                                      but it's a start!
 174 *              Marc Tamsky     :       Closing in closing fixes.
 175 *              Mike Shaver     :       RFC1122 verifications.
 176 *              Alan Cox        :       rcv_saddr errors.
 177 *              Alan Cox        :       Block double connect().
 178 *              Alan Cox        :       Small hooks for enSKIP.
 179 *              Alexey Kuznetsov:       Path MTU discovery.
 180 *              Alan Cox        :       Support soft errors.
 181 *              Alan Cox        :       Fix MTU discovery pathological case
 182 *                                      when the remote claims no mtu!
 183 *              Marc Tamsky     :       TCP_CLOSE fix.
 184 *              Colin (G3TNE)   :       Send a reset on syn ack replies in
 185 *                                      window but wrong (fixes NT lpd problems)
 186 *              Pedro Roque     :       Better TCP window handling, delayed ack.
 187 *              Joerg Reuter    :       No modification of locked buffers in
 188 *                                      tcp_do_retransmit()
 189 *              Eric Schenk     :       Changed receiver side silly window
 190 *                                      avoidance algorithm to BSD style
 191 *                                      algorithm. This doubles throughput
 192 *                                      against machines running Solaris,
 193 *                                      and seems to result in general
 194 *                                      improvement.
 195 *      Stefan Magdalinski      :       adjusted tcp_readable() to fix FIONREAD
 196 *      Willy Konynenberg       :       Transparent proxying support.
 197 *      Mike McLagan            :       Routing by source
 198 *              Keith Owens     :       Do proper merging with partial SKB's in
 199 *                                      tcp_do_sendmsg to avoid burstiness.
 200 *              Eric Schenk     :       Fix fast close down bug with
 201 *                                      shutdown() followed by close().
 202 *              Andi Kleen      :       Make poll agree with SIGIO
 203 *      Salvatore Sanfilippo    :       Support SO_LINGER with linger == 1 and
 204 *                                      lingertime == 0 (RFC 793 ABORT Call)
 205 *      Hirokazu Takahashi      :       Use copy_from_user() instead of
 206 *                                      csum_and_copy_from_user() if possible.
 207 *
 208 *              This program is free software; you can redistribute it and/or
 209 *              modify it under the terms of the GNU General Public License
 210 *              as published by the Free Software Foundation; either version
 211 *              2 of the License, or(at your option) any later version.
 212 *
 213 * Description of States:
 214 *
 215 *      TCP_SYN_SENT            sent a connection request, waiting for ack
 216 *
 217 *      TCP_SYN_RECV            received a connection request, sent ack,
 218 *                              waiting for final ack in three-way handshake.
 219 *
 220 *      TCP_ESTABLISHED         connection established
 221 *
 222 *      TCP_FIN_WAIT1           our side has shutdown, waiting to complete
 223 *                              transmission of remaining buffered data
 224 *
 225 *      TCP_FIN_WAIT2           all buffered data sent, waiting for remote
 226 *                              to shutdown
 227 *
 228 *      TCP_CLOSING             both sides have shutdown but we still have
 229 *                              data we have to finish sending
 230 *
 231 *      TCP_TIME_WAIT           timeout to catch resent junk before entering
 232 *                              closed, can only be entered from FIN_WAIT2
 233 *                              or CLOSING.  Required because the other end
 234 *                              may not have gotten our last ACK causing it
 235 *                              to retransmit the data packet (which we ignore)
 236 *
 237 *      TCP_CLOSE_WAIT          remote side has shutdown and is waiting for
 238 *                              us to finish writing our data and to shutdown
 239 *                              (we have to close() to move on to LAST_ACK)
 240 *
 241 *      TCP_LAST_ACK            out side has shutdown after remote has
 242 *                              shutdown.  There may still be data in our
 243 *                              buffer that we have to finish sending
 244 *
 245 *      TCP_CLOSE               socket is finished
 246 */
 247
 248#include <linux/kernel.h>
 249#include <linux/module.h>
 250#include <linux/types.h>
 251#include <linux/fcntl.h>
 252#include <linux/poll.h>
 253#include <linux/init.h>
 254#include <linux/fs.h>
 255#include <linux/skbuff.h>
 256#include <linux/scatterlist.h>
 257#include <linux/splice.h>
 258#include <linux/net.h>
 259#include <linux/socket.h>
 260#include <linux/random.h>
 261#include <linux/bootmem.h>
 262#include <linux/highmem.h>
 263#include <linux/swap.h>
 264#include <linux/cache.h>
 265#include <linux/err.h>
 266#include <linux/crypto.h>
 267
 268#include <net/icmp.h>
 269#include <net/tcp.h>
 270#include <net/xfrm.h>
 271#include <net/ip.h>
 272#include <net/netdma.h>
 273#include <net/sock.h>
 274
 275#include <asm/uaccess.h>
 276#include <asm/ioctls.h>
 277
 278int sysctl_tcp_fin_timeout __read_mostly = TCP_FIN_TIMEOUT;
 279
 280struct percpu_counter tcp_orphan_count;
 281EXPORT_SYMBOL_GPL(tcp_orphan_count);
 282
 283int sysctl_tcp_mem[3] __read_mostly;
 284int sysctl_tcp_wmem[3] __read_mostly;
 285int sysctl_tcp_rmem[3] __read_mostly;
 286
 287EXPORT_SYMBOL(sysctl_tcp_mem);
 288EXPORT_SYMBOL(sysctl_tcp_rmem);
 289EXPORT_SYMBOL(sysctl_tcp_wmem);
 290
 291atomic_t tcp_memory_allocated;  /* Current allocated memory. */
 292EXPORT_SYMBOL(tcp_memory_allocated);
 293
 294/*
 295 * Current number of TCP sockets.
 296 */
 297struct percpu_counter tcp_sockets_allocated;
 298EXPORT_SYMBOL(tcp_sockets_allocated);
 299
 300/*
 301 * TCP splice context
 302 */
 303struct tcp_splice_state {
 304        struct pipe_inode_info *pipe;
 305        size_t len;
 306        unsigned int flags;
 307};
 308
 309/*
 310 * Pressure flag: try to collapse.
 311 * Technical note: it is used by multiple contexts non atomically.
 312 * All the __sk_mem_schedule() is of this nature: accounting
 313 * is strict, actions are advisory and have some latency.
 314 */
 315int tcp_memory_pressure __read_mostly;
 316
 317EXPORT_SYMBOL(tcp_memory_pressure);
 318
 319void tcp_enter_memory_pressure(struct sock *sk)
 320{
 321        if (!tcp_memory_pressure) {
 322                NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMEMORYPRESSURES);
 323                tcp_memory_pressure = 1;
 324        }
 325}
 326
 327EXPORT_SYMBOL(tcp_enter_memory_pressure);
 328
 329/*
 330 *      Wait for a TCP event.
 331 *
 332 *      Note that we don't need to lock the socket, as the upper poll layers
 333 *      take care of normal races (between the test and the event) and we don't
 334 *      go look at any of the socket buffers directly.
 335 */
 336unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
 337{
 338        unsigned int mask;
 339        struct sock *sk = sock->sk;
 340        struct tcp_sock *tp = tcp_sk(sk);
 341
 342        poll_wait(file, sk->sk_sleep, wait);
 343        if (sk->sk_state == TCP_LISTEN)
 344                return inet_csk_listen_poll(sk);
 345
 346        /* Socket is not locked. We are protected from async events
 347         * by poll logic and correct handling of state changes
 348         * made by other threads is impossible in any case.
 349         */
 350
 351        mask = 0;
 352        if (sk->sk_err)
 353                mask = POLLERR;
 354
 355        /*
 356         * POLLHUP is certainly not done right. But poll() doesn't
 357         * have a notion of HUP in just one direction, and for a
 358         * socket the read side is more interesting.
 359         *
 360         * Some poll() documentation says that POLLHUP is incompatible
 361         * with the POLLOUT/POLLWR flags, so somebody should check this
 362         * all. But careful, it tends to be safer to return too many
 363         * bits than too few, and you can easily break real applications
 364         * if you don't tell them that something has hung up!
 365         *
 366         * Check-me.
 367         *
 368         * Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and
 369         * our fs/select.c). It means that after we received EOF,
 370         * poll always returns immediately, making impossible poll() on write()
 371         * in state CLOSE_WAIT. One solution is evident --- to set POLLHUP
 372         * if and only if shutdown has been made in both directions.
 373         * Actually, it is interesting to look how Solaris and DUX
 374         * solve this dilemma. I would prefer, if POLLHUP were maskable,
 375         * then we could set it on SND_SHUTDOWN. BTW examples given
 376         * in Stevens' books assume exactly this behaviour, it explains
 377         * why POLLHUP is incompatible with POLLOUT.    --ANK
 378         *
 379         * NOTE. Check for TCP_CLOSE is added. The goal is to prevent
 380         * blocking on fresh not-connected or disconnected socket. --ANK
 381         */
 382        if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == TCP_CLOSE)
 383                mask |= POLLHUP;
 384        if (sk->sk_shutdown & RCV_SHUTDOWN)
 385                mask |= POLLIN | POLLRDNORM | POLLRDHUP;
 386
 387        /* Connected? */
 388        if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV)) {
 389                int target = sock_rcvlowat(sk, 0, INT_MAX);
 390
 391                if (tp->urg_seq == tp->copied_seq &&
 392                    !sock_flag(sk, SOCK_URGINLINE) &&
 393                    tp->urg_data)
 394                        target--;
 395
 396                /* Potential race condition. If read of tp below will
 397                 * escape above sk->sk_state, we can be illegally awaken
 398                 * in SYN_* states. */
 399                if (tp->rcv_nxt - tp->copied_seq >= target)
 400                        mask |= POLLIN | POLLRDNORM;
 401
 402                if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
 403                        if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
 404                                mask |= POLLOUT | POLLWRNORM;
 405                        } else {  /* send SIGIO later */
 406                                set_bit(SOCK_ASYNC_NOSPACE,
 407                                        &sk->sk_socket->flags);
 408                                set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 409
 410                                /* Race breaker. If space is freed after
 411                                 * wspace test but before the flags are set,
 412                                 * IO signal will be lost.
 413                                 */
 414                                if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk))
 415                                        mask |= POLLOUT | POLLWRNORM;
 416                        }
 417                }
 418
 419                if (tp->urg_data & TCP_URG_VALID)
 420                        mask |= POLLPRI;
 421        }
 422        return mask;
 423}
 424
 425int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
 426{
 427        struct tcp_sock *tp = tcp_sk(sk);
 428        int answ;
 429
 430        switch (cmd) {
 431        case SIOCINQ:
 432                if (sk->sk_state == TCP_LISTEN)
 433                        return -EINVAL;
 434
 435                lock_sock(sk);
 436                if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
 437                        answ = 0;
 438                else if (sock_flag(sk, SOCK_URGINLINE) ||
 439                         !tp->urg_data ||
 440                         before(tp->urg_seq, tp->copied_seq) ||
 441                         !before(tp->urg_seq, tp->rcv_nxt)) {
 442                        answ = tp->rcv_nxt - tp->copied_seq;
 443
 444                        /* Subtract 1, if FIN is in queue. */
 445                        if (answ && !skb_queue_empty(&sk->sk_receive_queue))
 446                                answ -=
 447                       tcp_hdr((struct sk_buff *)sk->sk_receive_queue.prev)->fin;
 448                } else
 449                        answ = tp->urg_seq - tp->copied_seq;
 450                release_sock(sk);
 451                break;
 452        case SIOCATMARK:
 453                answ = tp->urg_data && tp->urg_seq == tp->copied_seq;
 454                break;
 455        case SIOCOUTQ:
 456                if (sk->sk_state == TCP_LISTEN)
 457                        return -EINVAL;
 458
 459                if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
 460                        answ = 0;
 461                else
 462                        answ = tp->write_seq - tp->snd_una;
 463                break;
 464        default:
 465                return -ENOIOCTLCMD;
 466        }
 467
 468        return put_user(answ, (int __user *)arg);
 469}
 470
 471static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
 472{
 473        TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH;
 474        tp->pushed_seq = tp->write_seq;
 475}
 476
 477static inline int forced_push(struct tcp_sock *tp)
 478{
 479        return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
 480}
 481
 482static inline void skb_entail(struct sock *sk, struct sk_buff *skb)
 483{
 484        struct tcp_sock *tp = tcp_sk(sk);
 485        struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
 486
 487        skb->csum    = 0;
 488        tcb->seq     = tcb->end_seq = tp->write_seq;
 489        tcb->flags   = TCPCB_FLAG_ACK;
 490        tcb->sacked  = 0;
 491        skb_header_release(skb);
 492        tcp_add_write_queue_tail(sk, skb);
 493        sk->sk_wmem_queued += skb->truesize;
 494        sk_mem_charge(sk, skb->truesize);
 495        if (tp->nonagle & TCP_NAGLE_PUSH)
 496                tp->nonagle &= ~TCP_NAGLE_PUSH;
 497}
 498
 499static inline void tcp_mark_urg(struct tcp_sock *tp, int flags,
 500                                struct sk_buff *skb)
 501{
 502        if (flags & MSG_OOB)
 503                tp->snd_up = tp->write_seq;
 504}
 505
 506static inline void tcp_push(struct sock *sk, int flags, int mss_now,
 507                            int nonagle)
 508{
 509        struct tcp_sock *tp = tcp_sk(sk);
 510
 511        if (tcp_send_head(sk)) {
 512                struct sk_buff *skb = tcp_write_queue_tail(sk);
 513                if (!(flags & MSG_MORE) || forced_push(tp))
 514                        tcp_mark_push(tp, skb);
 515                tcp_mark_urg(tp, flags, skb);
 516                __tcp_push_pending_frames(sk, mss_now,
 517                                          (flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle);
 518        }
 519}
 520
 521static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
 522                                unsigned int offset, size_t len)
 523{
 524        struct tcp_splice_state *tss = rd_desc->arg.data;
 525        int ret;
 526
 527        ret = skb_splice_bits(skb, offset, tss->pipe, min(rd_desc->count, len),
 528                              tss->flags);
 529        if (ret > 0)
 530                rd_desc->count -= ret;
 531        return ret;
 532}
 533
 534static int __tcp_splice_read(struct sock *sk, struct tcp_splice_state *tss)
 535{
 536        /* Store TCP splice context information in read_descriptor_t. */
 537        read_descriptor_t rd_desc = {
 538                .arg.data = tss,
 539                .count    = tss->len,
 540        };
 541
 542        return tcp_read_sock(sk, &rd_desc, tcp_splice_data_recv);
 543}
 544
 545/**
 546 *  tcp_splice_read - splice data from TCP socket to a pipe
 547 * @sock:       socket to splice from
 548 * @ppos:       position (not valid)
 549 * @pipe:       pipe to splice to
 550 * @len:        number of bytes to splice
 551 * @flags:      splice modifier flags
 552 *
 553 * Description:
 554 *    Will read pages from given socket and fill them into a pipe.
 555 *
 556 **/
 557ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
 558                        struct pipe_inode_info *pipe, size_t len,
 559                        unsigned int flags)
 560{
 561        struct sock *sk = sock->sk;
 562        struct tcp_splice_state tss = {
 563                .pipe = pipe,
 564                .len = len,
 565                .flags = flags,
 566        };
 567        long timeo;
 568        ssize_t spliced;
 569        int ret;
 570
 571        /*
 572         * We can't seek on a socket input
 573         */
 574        if (unlikely(*ppos))
 575                return -ESPIPE;
 576
 577        ret = spliced = 0;
 578
 579        lock_sock(sk);
 580
 581        timeo = sock_rcvtimeo(sk, flags & SPLICE_F_NONBLOCK);
 582        while (tss.len) {
 583                ret = __tcp_splice_read(sk, &tss);
 584                if (ret < 0)
 585                        break;
 586                else if (!ret) {
 587                        if (spliced)
 588                                break;
 589                        if (sock_flag(sk, SOCK_DONE))
 590                                break;
 591                        if (sk->sk_err) {
 592                                ret = sock_error(sk);
 593                                break;
 594                        }
 595                        if (sk->sk_shutdown & RCV_SHUTDOWN)
 596                                break;
 597                        if (sk->sk_state == TCP_CLOSE) {
 598                                /*
 599                                 * This occurs when user tries to read
 600                                 * from never connected socket.
 601                                 */
 602                                if (!sock_flag(sk, SOCK_DONE))
 603                                        ret = -ENOTCONN;
 604                                break;
 605                        }
 606                        if (!timeo) {
 607                                ret = -EAGAIN;
 608                                break;
 609                        }
 610                        sk_wait_data(sk, &timeo);
 611                        if (signal_pending(current)) {
 612                                ret = sock_intr_errno(timeo);
 613                                break;
 614                        }
 615                        continue;
 616                }
 617                tss.len -= ret;
 618                spliced += ret;
 619
 620                if (!timeo)
 621                        break;
 622                release_sock(sk);
 623                lock_sock(sk);
 624
 625                if (sk->sk_err || sk->sk_state == TCP_CLOSE ||
 626                    (sk->sk_shutdown & RCV_SHUTDOWN) ||
 627                    signal_pending(current))
 628                        break;
 629        }
 630
 631        release_sock(sk);
 632
 633        if (spliced)
 634                return spliced;
 635
 636        return ret;
 637}
 638
 639struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp)
 640{
 641        struct sk_buff *skb;
 642
 643        /* The TCP header must be at least 32-bit aligned.  */
 644        size = ALIGN(size, 4);
 645
 646        skb = alloc_skb_fclone(size + sk->sk_prot->max_header, gfp);
 647        if (skb) {
 648                if (sk_wmem_schedule(sk, skb->truesize)) {
 649                        /*
 650                         * Make sure that we have exactly size bytes
 651                         * available to the caller, no more, no less.
 652                         */
 653                        skb_reserve(skb, skb_tailroom(skb) - size);
 654                        return skb;
 655                }
 656                __kfree_skb(skb);
 657        } else {
 658                sk->sk_prot->enter_memory_pressure(sk);
 659                sk_stream_moderate_sndbuf(sk);
 660        }
 661        return NULL;
 662}
 663
 664static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,
 665                                       int large_allowed)
 666{
 667        struct tcp_sock *tp = tcp_sk(sk);
 668        u32 xmit_size_goal, old_size_goal;
 669
 670        xmit_size_goal = mss_now;
 671
 672        if (large_allowed && sk_can_gso(sk)) {
 673                xmit_size_goal = ((sk->sk_gso_max_size - 1) -
 674                                  inet_csk(sk)->icsk_af_ops->net_header_len -
 675                                  inet_csk(sk)->icsk_ext_hdr_len -
 676                                  tp->tcp_header_len);
 677
 678                xmit_size_goal = tcp_bound_to_half_wnd(tp, xmit_size_goal);
 679
 680                /* We try hard to avoid divides here */
 681                old_size_goal = tp->xmit_size_goal_segs * mss_now;
 682
 683                if (likely(old_size_goal <= xmit_size_goal &&
 684                           old_size_goal + mss_now > xmit_size_goal)) {
 685                        xmit_size_goal = old_size_goal;
 686                } else {
 687                        tp->xmit_size_goal_segs = xmit_size_goal / mss_now;
 688                        xmit_size_goal = tp->xmit_size_goal_segs * mss_now;
 689                }
 690        }
 691
 692        return max(xmit_size_goal, mss_now);
 693}
 694
 695static int tcp_send_mss(struct sock *sk, int *size_goal, int flags)
 696{
 697        int mss_now;
 698
 699        mss_now = tcp_current_mss(sk);
 700        *size_goal = tcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));
 701
 702        return mss_now;
 703}
 704
 705static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset,
 706                         size_t psize, int flags)
 707{
 708        struct tcp_sock *tp = tcp_sk(sk);
 709        int mss_now, size_goal;
 710        int err;
 711        ssize_t copied;
 712        long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 713
 714        /* Wait for a connection to finish. */
 715        if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
 716                if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
 717                        goto out_err;
 718
 719        clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 720
 721        mss_now = tcp_send_mss(sk, &size_goal, flags);
 722        copied = 0;
 723
 724        err = -EPIPE;
 725        if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 726                goto out_err;
 727
 728        while (psize > 0) {
 729                struct sk_buff *skb = tcp_write_queue_tail(sk);
 730                struct page *page = pages[poffset / PAGE_SIZE];
 731                int copy, i, can_coalesce;
 732                int offset = poffset % PAGE_SIZE;
 733                int size = min_t(size_t, psize, PAGE_SIZE - offset);
 734
 735                if (!tcp_send_head(sk) || (copy = size_goal - skb->len) <= 0) {
 736new_segment:
 737                        if (!sk_stream_memory_free(sk))
 738                                goto wait_for_sndbuf;
 739
 740                        skb = sk_stream_alloc_skb(sk, 0, sk->sk_allocation);
 741                        if (!skb)
 742                                goto wait_for_memory;
 743
 744                        skb_entail(sk, skb);
 745                        copy = size_goal;
 746                }
 747
 748                if (copy > size)
 749                        copy = size;
 750
 751                i = skb_shinfo(skb)->nr_frags;
 752                can_coalesce = skb_can_coalesce(skb, i, page, offset);
 753                if (!can_coalesce && i >= MAX_SKB_FRAGS) {
 754                        tcp_mark_push(tp, skb);
 755                        goto new_segment;
 756                }
 757                if (!sk_wmem_schedule(sk, copy))
 758                        goto wait_for_memory;
 759
 760                if (can_coalesce) {
 761                        skb_shinfo(skb)->frags[i - 1].size += copy;
 762                } else {
 763                        get_page(page);
 764                        skb_fill_page_desc(skb, i, page, offset, copy);
 765                }
 766
 767                skb->len += copy;
 768                skb->data_len += copy;
 769                skb->truesize += copy;
 770                sk->sk_wmem_queued += copy;
 771                sk_mem_charge(sk, copy);
 772                skb->ip_summed = CHECKSUM_PARTIAL;
 773                tp->write_seq += copy;
 774                TCP_SKB_CB(skb)->end_seq += copy;
 775                skb_shinfo(skb)->gso_segs = 0;
 776
 777                if (!copied)
 778                        TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
 779
 780                copied += copy;
 781                poffset += copy;
 782                if (!(psize -= copy))
 783                        goto out;
 784
 785                if (skb->len < size_goal || (flags & MSG_OOB))
 786                        continue;
 787
 788                if (forced_push(tp)) {
 789                        tcp_mark_push(tp, skb);
 790                        __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
 791                } else if (skb == tcp_send_head(sk))
 792                        tcp_push_one(sk, mss_now);
 793                continue;
 794
 795wait_for_sndbuf:
 796                set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 797wait_for_memory:
 798                if (copied)
 799                        tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
 800
 801                if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
 802                        goto do_error;
 803
 804                mss_now = tcp_send_mss(sk, &size_goal, flags);
 805        }
 806
 807out:
 808        if (copied)
 809                tcp_push(sk, flags, mss_now, tp->nonagle);
 810        return copied;
 811
 812do_error:
 813        if (copied)
 814                goto out;
 815out_err:
 816        return sk_stream_error(sk, flags, err);
 817}
 818
 819ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset,
 820                     size_t size, int flags)
 821{
 822        ssize_t res;
 823        struct sock *sk = sock->sk;
 824
 825        if (!(sk->sk_route_caps & NETIF_F_SG) ||
 826            !(sk->sk_route_caps & NETIF_F_ALL_CSUM))
 827                return sock_no_sendpage(sock, page, offset, size, flags);
 828
 829        lock_sock(sk);
 830        TCP_CHECK_TIMER(sk);
 831        res = do_tcp_sendpages(sk, &page, offset, size, flags);
 832        TCP_CHECK_TIMER(sk);
 833        release_sock(sk);
 834        return res;
 835}
 836
 837#define TCP_PAGE(sk)    (sk->sk_sndmsg_page)
 838#define TCP_OFF(sk)     (sk->sk_sndmsg_off)
 839
 840static inline int select_size(struct sock *sk)
 841{
 842        struct tcp_sock *tp = tcp_sk(sk);
 843        int tmp = tp->mss_cache;
 844
 845        if (sk->sk_route_caps & NETIF_F_SG) {
 846                if (sk_can_gso(sk))
 847                        tmp = 0;
 848                else {
 849                        int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
 850
 851                        if (tmp >= pgbreak &&
 852                            tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
 853                                tmp = pgbreak;
 854                }
 855        }
 856
 857        return tmp;
 858}
 859
 860int tcp_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
 861                size_t size)
 862{
 863        struct sock *sk = sock->sk;
 864        struct iovec *iov;
 865        struct tcp_sock *tp = tcp_sk(sk);
 866        struct sk_buff *skb;
 867        int iovlen, flags;
 868        int mss_now, size_goal;
 869        int err, copied;
 870        long timeo;
 871
 872        lock_sock(sk);
 873        TCP_CHECK_TIMER(sk);
 874
 875        flags = msg->msg_flags;
 876        timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 877
 878        /* Wait for a connection to finish. */
 879        if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
 880                if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
 881                        goto out_err;
 882
 883        /* This should be in poll */
 884        clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 885
 886        mss_now = tcp_send_mss(sk, &size_goal, flags);
 887
 888        /* Ok commence sending. */
 889        iovlen = msg->msg_iovlen;
 890        iov = msg->msg_iov;
 891        copied = 0;
 892
 893        err = -EPIPE;
 894        if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 895                goto out_err;
 896
 897        while (--iovlen >= 0) {
 898                int seglen = iov->iov_len;
 899                unsigned char __user *from = iov->iov_base;
 900
 901                iov++;
 902
 903                while (seglen > 0) {
 904                        int copy;
 905
 906                        skb = tcp_write_queue_tail(sk);
 907
 908                        if (!tcp_send_head(sk) ||
 909                            (copy = size_goal - skb->len) <= 0) {
 910
 911new_segment:
 912                                /* Allocate new segment. If the interface is SG,
 913                                 * allocate skb fitting to single page.
 914                                 */
 915                                if (!sk_stream_memory_free(sk))
 916                                        goto wait_for_sndbuf;
 917
 918                                skb = sk_stream_alloc_skb(sk, select_size(sk),
 919                                                sk->sk_allocation);
 920                                if (!skb)
 921                                        goto wait_for_memory;
 922
 923                                /*
 924                                 * Check whether we can use HW checksum.
 925                                 */
 926                                if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
 927                                        skb->ip_summed = CHECKSUM_PARTIAL;
 928
 929                                skb_entail(sk, skb);
 930                                copy = size_goal;
 931                        }
 932
 933                        /* Try to append data to the end of skb. */
 934                        if (copy > seglen)
 935                                copy = seglen;
 936
 937                        /* Where to copy to? */
 938                        if (skb_tailroom(skb) > 0) {
 939                                /* We have some space in skb head. Superb! */
 940                                if (copy > skb_tailroom(skb))
 941                                        copy = skb_tailroom(skb);
 942                                if ((err = skb_add_data(skb, from, copy)) != 0)
 943                                        goto do_fault;
 944                        } else {
 945                                int merge = 0;
 946                                int i = skb_shinfo(skb)->nr_frags;
 947                                struct page *page = TCP_PAGE(sk);
 948                                int off = TCP_OFF(sk);
 949
 950                                if (skb_can_coalesce(skb, i, page, off) &&
 951                                    off != PAGE_SIZE) {
 952                                        /* We can extend the last page
 953                                         * fragment. */
 954                                        merge = 1;
 955                                } else if (i == MAX_SKB_FRAGS ||
 956                                           (!i &&
 957                                           !(sk->sk_route_caps & NETIF_F_SG))) {
 958                                        /* Need to add new fragment and cannot
 959                                         * do this because interface is non-SG,
 960                                         * or because all the page slots are
 961                                         * busy. */
 962                                        tcp_mark_push(tp, skb);
 963                                        goto new_segment;
 964                                } else if (page) {
 965                                        if (off == PAGE_SIZE) {
 966                                                put_page(page);
 967                                                TCP_PAGE(sk) = page = NULL;
 968                                                off = 0;
 969                                        }
 970                                } else
 971                                        off = 0;
 972
 973                                if (copy > PAGE_SIZE - off)
 974                                        copy = PAGE_SIZE - off;
 975
 976                                if (!sk_wmem_schedule(sk, copy))
 977                                        goto wait_for_memory;
 978
 979                                if (!page) {
 980                                        /* Allocate new cache page. */
 981                                        if (!(page = sk_stream_alloc_page(sk)))
 982                                                goto wait_for_memory;
 983                                }
 984
 985                                /* Time to copy data. We are close to
 986                                 * the end! */
 987                                err = skb_copy_to_page(sk, from, skb, page,
 988                                                       off, copy);
 989                                if (err) {
 990                                        /* If this page was new, give it to the
 991                                         * socket so it does not get leaked.
 992                                         */
 993                                        if (!TCP_PAGE(sk)) {
 994                                                TCP_PAGE(sk) = page;
 995                                                TCP_OFF(sk) = 0;
 996                                        }
 997                                        goto do_error;
 998                                }
 999
1000                                /* Update the skb. */
1001                                if (merge) {
1002                                        skb_shinfo(skb)->frags[i - 1].size +=
1003                                                                        copy;
1004                                } else {
1005                                        skb_fill_page_desc(skb, i, page, off, copy);
1006                                        if (TCP_PAGE(sk)) {
1007                                                get_page(page);
1008                                        } else if (off + copy < PAGE_SIZE) {
1009                                                get_page(page);
1010                                                TCP_PAGE(sk) = page;
1011                                        }
1012                                }
1013
1014                                TCP_OFF(sk) = off + copy;
1015                        }
1016
1017                        if (!copied)
1018                                TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
1019
1020                        tp->write_seq += copy;
1021                        TCP_SKB_CB(skb)->end_seq += copy;
1022                        skb_shinfo(skb)->gso_segs = 0;
1023
1024                        from += copy;
1025                        copied += copy;
1026                        if ((seglen -= copy) == 0 && iovlen == 0)
1027                                goto out;
1028
1029                        if (skb->len < size_goal || (flags & MSG_OOB))
1030                                continue;
1031
1032                        if (forced_push(tp)) {
1033                                tcp_mark_push(tp, skb);
1034                                __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
1035                        } else if (skb == tcp_send_head(sk))
1036                                tcp_push_one(sk, mss_now);
1037                        continue;
1038
1039wait_for_sndbuf:
1040                        set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
1041wait_for_memory:
1042                        if (copied)
1043                                tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
1044
1045                        if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
1046                                goto do_error;
1047
1048                        mss_now = tcp_send_mss(sk, &size_goal, flags);
1049                }
1050        }
1051
1052out:
1053        if (copied)
1054                tcp_push(sk, flags, mss_now, tp->nonagle);
1055        TCP_CHECK_TIMER(sk);
1056        release_sock(sk);
1057        return copied;
1058
1059do_fault:
1060        if (!skb->len) {
1061                tcp_unlink_write_queue(skb, sk);
1062                /* It is the one place in all of TCP, except connection
1063                 * reset, where we can be unlinking the send_head.
1064                 */
1065                tcp_check_send_head(sk, skb);
1066                sk_wmem_free_skb(sk, skb);
1067        }
1068
1069do_error:
1070        if (copied)
1071                goto out;
1072out_err:
1073        err = sk_stream_error(sk, flags, err);
1074        TCP_CHECK_TIMER(sk);
1075        release_sock(sk);
1076        return err;
1077}
1078
1079/*
1080 *      Handle reading urgent data. BSD has very simple semantics for
1081 *      this, no blocking and very strange errors 8)
1082 */
1083
1084static int tcp_recv_urg(struct sock *sk, struct msghdr *msg, int len, int flags)
1085{
1086        struct tcp_sock *tp = tcp_sk(sk);
1087
1088        /* No URG data to read. */
1089        if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
1090            tp->urg_data == TCP_URG_READ)
1091                return -EINVAL; /* Yes this is right ! */
1092
1093        if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
1094                return -ENOTCONN;
1095
1096        if (tp->urg_data & TCP_URG_VALID) {
1097                int err = 0;
1098                char c = tp->urg_data;
1099
1100                if (!(flags & MSG_PEEK))
1101                        tp->urg_data = TCP_URG_READ;
1102
1103                /* Read urgent data. */
1104                msg->msg_flags |= MSG_OOB;
1105
1106                if (len > 0) {
1107                        if (!(flags & MSG_TRUNC))
1108                                err = memcpy_toiovec(msg->msg_iov, &c, 1);
1109                        len = 1;
1110                } else
1111                        msg->msg_flags |= MSG_TRUNC;
1112
1113                return err ? -EFAULT : len;
1114        }
1115
1116        if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
1117                return 0;
1118
1119        /* Fixed the recv(..., MSG_OOB) behaviour.  BSD docs and
1120         * the available implementations agree in this case:
1121         * this call should never block, independent of the
1122         * blocking state of the socket.
1123         * Mike <pall@rz.uni-karlsruhe.de>
1124         */
1125        return -EAGAIN;
1126}
1127
1128/* Clean up the receive buffer for full frames taken by the user,
1129 * then send an ACK if necessary.  COPIED is the number of bytes
1130 * tcp_recvmsg has given to the user so far, it speeds up the
1131 * calculation of whether or not we must ACK for the sake of
1132 * a window update.
1133 */
1134void tcp_cleanup_rbuf(struct sock *sk, int copied)
1135{
1136        struct tcp_sock *tp = tcp_sk(sk);
1137        int time_to_ack = 0;
1138
1139#if TCP_DEBUG
1140        struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
1141
1142        WARN_ON(skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq));
1143#endif
1144
1145        if (inet_csk_ack_scheduled(sk)) {
1146                const struct inet_connection_sock *icsk = inet_csk(sk);
1147                   /* Delayed ACKs frequently hit locked sockets during bulk
1148                    * receive. */
1149                if (icsk->icsk_ack.blocked ||
1150                    /* Once-per-two-segments ACK was not sent by tcp_input.c */
1151                    tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
1152                    /*
1153                     * If this read emptied read buffer, we send ACK, if
1154                     * connection is not bidirectional, user drained
1155                     * receive buffer and there was a small segment
1156                     * in queue.
1157                     */
1158                    (copied > 0 &&
1159                     ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) ||
1160                      ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
1161                       !icsk->icsk_ack.pingpong)) &&
1162                      !atomic_read(&sk->sk_rmem_alloc)))
1163                        time_to_ack = 1;
1164        }
1165
1166        /* We send an ACK if we can now advertise a non-zero window
1167         * which has been raised "significantly".
1168         *
1169         * Even if window raised up to infinity, do not send window open ACK
1170         * in states, where we will not receive more. It is useless.
1171         */
1172        if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
1173                __u32 rcv_window_now = tcp_receive_window(tp);
1174
1175                /* Optimize, __tcp_select_window() is not cheap. */
1176                if (2*rcv_window_now <= tp->window_clamp) {
1177                        __u32 new_window = __tcp_select_window(sk);
1178
1179                        /* Send ACK now, if this read freed lots of space
1180                         * in our buffer. Certainly, new_window is new window.
1181                         * We can advertise it now, if it is not less than current one.
1182                         * "Lots" means "at least twice" here.
1183                         */
1184                        if (new_window && new_window >= 2 * rcv_window_now)
1185                                time_to_ack = 1;
1186                }
1187        }
1188        if (time_to_ack)
1189                tcp_send_ack(sk);
1190}
1191
1192static void tcp_prequeue_process(struct sock *sk)
1193{
1194        struct sk_buff *skb;
1195        struct tcp_sock *tp = tcp_sk(sk);
1196
1197        NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPPREQUEUED);
1198
1199        /* RX process wants to run with disabled BHs, though it is not
1200         * necessary */
1201        local_bh_disable();
1202        while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)
1203                sk_backlog_rcv(sk, skb);
1204        local_bh_enable();
1205
1206        /* Clear memory counter. */
1207        tp->ucopy.memory = 0;
1208}
1209
1210static inline struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
1211{
1212        struct sk_buff *skb;
1213        u32 offset;
1214
1215        skb_queue_walk(&sk->sk_receive_queue, skb) {
1216                offset = seq - TCP_SKB_CB(skb)->seq;
1217                if (tcp_hdr(skb)->syn)
1218                        offset--;
1219                if (offset < skb->len || tcp_hdr(skb)->fin) {
1220                        *off = offset;
1221                        return skb;
1222                }
1223        }
1224        return NULL;
1225}
1226
1227/*
1228 * This routine provides an alternative to tcp_recvmsg() for routines
1229 * that would like to handle copying from skbuffs directly in 'sendfile'
1230 * fashion.
1231 * Note:
1232 *      - It is assumed that the socket was locked by the caller.
1233 *      - The routine does not block.
1234 *      - At present, there is no support for reading OOB data
1235 *        or for 'peeking' the socket using this routine
1236 *        (although both would be easy to implement).
1237 */
1238int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
1239                  sk_read_actor_t recv_actor)
1240{
1241        struct sk_buff *skb;
1242        struct tcp_sock *tp = tcp_sk(sk);
1243        u32 seq = tp->copied_seq;
1244        u32 offset;
1245        int copied = 0;
1246
1247        if (sk->sk_state == TCP_LISTEN)
1248                return -ENOTCONN;
1249        while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
1250                if (offset < skb->len) {
1251                        int used;
1252                        size_t len;
1253
1254                        len = skb->len - offset;
1255                        /* Stop reading if we hit a patch of urgent data */
1256                        if (tp->urg_data) {
1257                                u32 urg_offset = tp->urg_seq - seq;
1258                                if (urg_offset < len)
1259                                        len = urg_offset;
1260                                if (!len)
1261                                        break;
1262                        }
1263                        used = recv_actor(desc, skb, offset, len);
1264                        if (used < 0) {
1265                                if (!copied)
1266                                        copied = used;
1267                                break;
1268                        } else if (used <= len) {
1269                                seq += used;
1270                                copied += used;
1271                                offset += used;
1272                        }
1273                        /*
1274                         * If recv_actor drops the lock (e.g. TCP splice
1275                         * receive) the skb pointer might be invalid when
1276                         * getting here: tcp_collapse might have deleted it
1277                         * while aggregating skbs from the socket queue.
1278                         */
1279                        skb = tcp_recv_skb(sk, seq-1, &offset);
1280                        if (!skb || (offset+1 != skb->len))
1281                                break;
1282                }
1283                if (tcp_hdr(skb)->fin) {
1284                        sk_eat_skb(sk, skb, 0);
1285                        ++seq;
1286                        break;
1287                }
1288                sk_eat_skb(sk, skb, 0);
1289                if (!desc->count)
1290                        break;
1291        }
1292        tp->copied_seq = seq;
1293
1294        tcp_rcv_space_adjust(sk);
1295
1296        /* Clean up data we have read: This will do ACK frames. */
1297        if (copied > 0)
1298                tcp_cleanup_rbuf(sk, copied);
1299        return copied;
1300}
1301
1302/*
1303 *      This routine copies from a sock struct into the user buffer.
1304 *
1305 *      Technical note: in 2.3 we work on _locked_ socket, so that
1306 *      tricks with *seq access order and skb->users are not required.
1307 *      Probably, code can be easily improved even more.
1308 */
1309
1310int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
1311                size_t len, int nonblock, int flags, int *addr_len)
1312{
1313        struct tcp_sock *tp = tcp_sk(sk);
1314        int copied = 0;
1315        u32 peek_seq;
1316        u32 *seq;
1317        unsigned long used;
1318        int err;
1319        int target;             /* Read at least this many bytes */
1320        long timeo;
1321        struct task_struct *user_recv = NULL;
1322        int copied_early = 0;
1323        struct sk_buff *skb;
1324        u32 urg_hole = 0;
1325
1326        lock_sock(sk);
1327
1328        TCP_CHECK_TIMER(sk);
1329
1330        err = -ENOTCONN;
1331        if (sk->sk_state == TCP_LISTEN)
1332                goto out;
1333
1334        timeo = sock_rcvtimeo(sk, nonblock);
1335
1336        /* Urgent data needs to be handled specially. */
1337        if (flags & MSG_OOB)
1338                goto recv_urg;
1339
1340        seq = &tp->copied_seq;
1341        if (flags & MSG_PEEK) {
1342                peek_seq = tp->copied_seq;
1343                seq = &peek_seq;
1344        }
1345
1346        target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
1347
1348#ifdef CONFIG_NET_DMA
1349        tp->ucopy.dma_chan = NULL;
1350        preempt_disable();
1351        skb = skb_peek_tail(&sk->sk_receive_queue);
1352        {
1353                int available = 0;
1354
1355                if (skb)
1356                        available = TCP_SKB_CB(skb)->seq + skb->len - (*seq);
1357                if ((available < target) &&
1358                    (len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) &&
1359                    !sysctl_tcp_low_latency &&
1360                    dma_find_channel(DMA_MEMCPY)) {
1361                        preempt_enable_no_resched();
1362                        tp->ucopy.pinned_list =
1363                                        dma_pin_iovec_pages(msg->msg_iov, len);
1364                } else {
1365                        preempt_enable_no_resched();
1366                }
1367        }
1368#endif
1369
1370        do {
1371                u32 offset;
1372
1373                /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
1374                if (tp->urg_data && tp->urg_seq == *seq) {
1375                        if (copied)
1376                                break;
1377                        if (signal_pending(current)) {
1378                                copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
1379                                break;
1380                        }
1381                }
1382
1383                /* Next get a buffer. */
1384
1385                skb = skb_peek(&sk->sk_receive_queue);
1386                do {
1387                        if (!skb)
1388                                break;
1389
1390                        /* Now that we have two receive queues this
1391                         * shouldn't happen.
1392                         */
1393                        if (before(*seq, TCP_SKB_CB(skb)->seq)) {
1394                                printk(KERN_INFO "recvmsg bug: copied %X "
1395                                       "seq %X\n", *seq, TCP_SKB_CB(skb)->seq);
1396                                break;
1397                        }
1398                        offset = *seq - TCP_SKB_CB(skb)->seq;
1399                        if (tcp_hdr(skb)->syn)
1400                                offset--;
1401                        if (offset < skb->len)
1402                                goto found_ok_skb;
1403                        if (tcp_hdr(skb)->fin)
1404                                goto found_fin_ok;
1405                        WARN_ON(!(flags & MSG_PEEK));
1406                        skb = skb->next;
1407                } while (skb != (struct sk_buff *)&sk->sk_receive_queue);
1408
1409                /* Well, if we have backlog, try to process it now yet. */
1410
1411                if (copied >= target && !sk->sk_backlog.tail)
1412                        break;
1413
1414                if (copied) {
1415                        if (sk->sk_err ||
1416                            sk->sk_state == TCP_CLOSE ||
1417                            (sk->sk_shutdown & RCV_SHUTDOWN) ||
1418                            !timeo ||
1419                            signal_pending(current))
1420                                break;
1421                } else {
1422                        if (sock_flag(sk, SOCK_DONE))
1423                                break;
1424
1425                        if (sk->sk_err) {
1426                                copied = sock_error(sk);
1427                                break;
1428                        }
1429
1430                        if (sk->sk_shutdown & RCV_SHUTDOWN)
1431                                break;
1432
1433                        if (sk->sk_state == TCP_CLOSE) {
1434                                if (!sock_flag(sk, SOCK_DONE)) {
1435                                        /* This occurs when user tries to read
1436                                         * from never connected socket.
1437                                         */
1438                                        copied = -ENOTCONN;
1439                                        break;
1440                                }
1441                                break;
1442                        }
1443
1444                        if (!timeo) {
1445                                copied = -EAGAIN;
1446                                break;
1447                        }
1448
1449                        if (signal_pending(current)) {
1450                                copied = sock_intr_errno(timeo);
1451                                break;
1452                        }
1453                }
1454
1455                tcp_cleanup_rbuf(sk, copied);
1456
1457                if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) {
1458                        /* Install new reader */
1459                        if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) {
1460                                user_recv = current;
1461                                tp->ucopy.task = user_recv;
1462                                tp->ucopy.iov = msg->msg_iov;
1463                        }
1464
1465                        tp->ucopy.len = len;
1466
1467                        WARN_ON(tp->copied_seq != tp->rcv_nxt &&
1468                                !(flags & (MSG_PEEK | MSG_TRUNC)));
1469
1470                        /* Ugly... If prequeue is not empty, we have to
1471                         * process it before releasing socket, otherwise
1472                         * order will be broken at second iteration.
1473                         * More elegant solution is required!!!
1474                         *
1475                         * Look: we have the following (pseudo)queues:
1476                         *
1477                         * 1. packets in flight
1478                         * 2. backlog
1479                         * 3. prequeue
1480                         * 4. receive_queue
1481                         *
1482                         * Each queue can be processed only if the next ones
1483                         * are empty. At this point we have empty receive_queue.
1484                         * But prequeue _can_ be not empty after 2nd iteration,
1485                         * when we jumped to start of loop because backlog
1486                         * processing added something to receive_queue.
1487                         * We cannot release_sock(), because backlog contains
1488                         * packets arrived _after_ prequeued ones.
1489                         *
1490                         * Shortly, algorithm is clear --- to process all
1491                         * the queues in order. We could make it more directly,
1492                         * requeueing packets from backlog to prequeue, if
1493                         * is not empty. It is more elegant, but eats cycles,
1494                         * unfortunately.
1495                         */
1496                        if (!skb_queue_empty(&tp->ucopy.prequeue))
1497                                goto do_prequeue;
1498
1499                        /* __ Set realtime policy in scheduler __ */
1500                }
1501
1502                if (copied >= target) {
1503                        /* Do not sleep, just process backlog. */
1504                        release_sock(sk);
1505                        lock_sock(sk);
1506                } else
1507                        sk_wait_data(sk, &timeo);
1508
1509#ifdef CONFIG_NET_DMA
1510                tp->ucopy.wakeup = 0;
1511#endif
1512
1513                if (user_recv) {
1514                        int chunk;
1515
1516                        /* __ Restore normal policy in scheduler __ */
1517
1518                        if ((chunk = len - tp->ucopy.len) != 0) {
1519                                NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk);
1520                                len -= chunk;
1521                                copied += chunk;
1522                        }
1523
1524                        if (tp->rcv_nxt == tp->copied_seq &&
1525                            !skb_queue_empty(&tp->ucopy.prequeue)) {
1526do_prequeue:
1527                                tcp_prequeue_process(sk);
1528
1529                                if ((chunk = len - tp->ucopy.len) != 0) {
1530                                        NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1531                                        len -= chunk;
1532                                        copied += chunk;
1533                                }
1534                        }
1535                }
1536                if ((flags & MSG_PEEK) &&
1537                    (peek_seq - copied - urg_hole != tp->copied_seq)) {
1538                        if (net_ratelimit())
1539                                printk(KERN_DEBUG "TCP(%s:%d): Application bug, race in MSG_PEEK.\n",
1540                                       current->comm, task_pid_nr(current));
1541                        peek_seq = tp->copied_seq;
1542                }
1543                continue;
1544
1545        found_ok_skb:
1546                /* Ok so how much can we use? */
1547                used = skb->len - offset;
1548                if (len < used)
1549                        used = len;
1550
1551                /* Do we have urgent data here? */
1552                if (tp->urg_data) {
1553                        u32 urg_offset = tp->urg_seq - *seq;
1554                        if (urg_offset < used) {
1555                                if (!urg_offset) {
1556                                        if (!sock_flag(sk, SOCK_URGINLINE)) {
1557                                                ++*seq;
1558                                                urg_hole++;
1559                                                offset++;
1560                                                used--;
1561                                                if (!used)
1562                                                        goto skip_copy;
1563                                        }
1564                                } else
1565                                        used = urg_offset;
1566                        }
1567                }
1568
1569                if (!(flags & MSG_TRUNC)) {
1570#ifdef CONFIG_NET_DMA
1571                        if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1572                                tp->ucopy.dma_chan = dma_find_channel(DMA_MEMCPY);
1573
1574                        if (tp->ucopy.dma_chan) {
1575                                tp->ucopy.dma_cookie = dma_skb_copy_datagram_iovec(
1576                                        tp->ucopy.dma_chan, skb, offset,
1577                                        msg->msg_iov, used,
1578                                        tp->ucopy.pinned_list);
1579
1580                                if (tp->ucopy.dma_cookie < 0) {
1581
1582                                        printk(KERN_ALERT "dma_cookie < 0\n");
1583
1584                                        /* Exception. Bailout! */
1585                                        if (!copied)
1586                                                copied = -EFAULT;
1587                                        break;
1588                                }
1589                                if ((offset + used) == skb->len)
1590                                        copied_early = 1;
1591
1592                        } else
1593#endif
1594                        {
1595                                err = skb_copy_datagram_iovec(skb, offset,
1596                                                msg->msg_iov, used);
1597                                if (err) {
1598                                        /* Exception. Bailout! */
1599                                        if (!copied)
1600                                                copied = -EFAULT;
1601                                        break;
1602                                }
1603                        }
1604                }
1605
1606                *seq += used;
1607                copied += used;
1608                len -= used;
1609
1610                tcp_rcv_space_adjust(sk);
1611
1612skip_copy:
1613                if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) {
1614                        tp->urg_data = 0;
1615                        tcp_fast_path_check(sk);
1616                }
1617                if (used + offset < skb->len)
1618                        continue;
1619
1620                if (tcp_hdr(skb)->fin)
1621                        goto found_fin_ok;
1622                if (!(flags & MSG_PEEK)) {
1623                        sk_eat_skb(sk, skb, copied_early);
1624                        copied_early = 0;
1625                }
1626                continue;
1627
1628        found_fin_ok:
1629                /* Process the FIN. */
1630                ++*seq;
1631                if (!(flags & MSG_PEEK)) {
1632                        sk_eat_skb(sk, skb, copied_early);
1633                        copied_early = 0;
1634                }
1635                break;
1636        } while (len > 0);
1637
1638        if (user_recv) {
1639                if (!skb_queue_empty(&tp->ucopy.prequeue)) {
1640                        int chunk;
1641
1642                        tp->ucopy.len = copied > 0 ? len : 0;
1643
1644                        tcp_prequeue_process(sk);
1645
1646                        if (copied > 0 && (chunk = len - tp->ucopy.len) != 0) {
1647                                NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1648                                len -= chunk;
1649                                copied += chunk;
1650                        }
1651                }
1652
1653                tp->ucopy.task = NULL;
1654                tp->ucopy.len = 0;
1655        }
1656
1657#ifdef CONFIG_NET_DMA
1658        if (tp->ucopy.dma_chan) {
1659                dma_cookie_t done, used;
1660
1661                dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
1662
1663                while (dma_async_memcpy_complete(tp->ucopy.dma_chan,
1664                                                 tp->ucopy.dma_cookie, &done,
1665                                                 &used) == DMA_IN_PROGRESS) {
1666                        /* do partial cleanup of sk_async_wait_queue */
1667                        while ((skb = skb_peek(&sk->sk_async_wait_queue)) &&
1668                               (dma_async_is_complete(skb->dma_cookie, done,
1669                                                      used) == DMA_SUCCESS)) {
1670                                __skb_dequeue(&sk->sk_async_wait_queue);
1671                                kfree_skb(skb);
1672                        }
1673                }
1674
1675                /* Safe to free early-copied skbs now */
1676                __skb_queue_purge(&sk->sk_async_wait_queue);
1677                tp->ucopy.dma_chan = NULL;
1678        }
1679        if (tp->ucopy.pinned_list) {
1680                dma_unpin_iovec_pages(tp->ucopy.pinned_list);
1681                tp->ucopy.pinned_list = NULL;
1682        }
1683#endif
1684
1685        /* According to UNIX98, msg_name/msg_namelen are ignored
1686         * on connected socket. I was just happy when found this 8) --ANK
1687         */
1688
1689        /* Clean up data we have read: This will do ACK frames. */
1690        tcp_cleanup_rbuf(sk, copied);
1691
1692        TCP_CHECK_TIMER(sk);
1693        release_sock(sk);
1694        return copied;
1695
1696out:
1697        TCP_CHECK_TIMER(sk);
1698        release_sock(sk);
1699        return err;
1700
1701recv_urg:
1702        err = tcp_recv_urg(sk, msg, len, flags);
1703        goto out;
1704}
1705
1706void tcp_set_state(struct sock *sk, int state)
1707{
1708        int oldstate = sk->sk_state;
1709
1710        switch (state) {
1711        case TCP_ESTABLISHED:
1712                if (oldstate != TCP_ESTABLISHED)
1713                        TCP_INC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1714                break;
1715
1716        case TCP_CLOSE:
1717                if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
1718                        TCP_INC_STATS(sock_net(sk), TCP_MIB_ESTABRESETS);
1719
1720                sk->sk_prot->unhash(sk);
1721                if (inet_csk(sk)->icsk_bind_hash &&
1722                    !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
1723                        inet_put_port(sk);
1724                /* fall through */
1725        default:
1726                if (oldstate == TCP_ESTABLISHED)
1727                        TCP_DEC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1728        }
1729
1730        /* Change state AFTER socket is unhashed to avoid closed
1731         * socket sitting in hash tables.
1732         */
1733        sk->sk_state = state;
1734
1735#ifdef STATE_TRACE
1736        SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n", sk, statename[oldstate], statename[state]);
1737#endif
1738}
1739EXPORT_SYMBOL_GPL(tcp_set_state);
1740
1741/*
1742 *      State processing on a close. This implements the state shift for
1743 *      sending our FIN frame. Note that we only send a FIN for some
1744 *      states. A shutdown() may have already sent the FIN, or we may be
1745 *      closed.
1746 */
1747
1748static const unsigned char new_state[16] = {
1749  /* current state:        new state:      action:      */
1750  /* (Invalid)          */ TCP_CLOSE,
1751  /* TCP_ESTABLISHED    */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1752  /* TCP_SYN_SENT       */ TCP_CLOSE,
1753  /* TCP_SYN_RECV       */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1754  /* TCP_FIN_WAIT1      */ TCP_FIN_WAIT1,
1755  /* TCP_FIN_WAIT2      */ TCP_FIN_WAIT2,
1756  /* TCP_TIME_WAIT      */ TCP_CLOSE,
1757  /* TCP_CLOSE          */ TCP_CLOSE,
1758  /* TCP_CLOSE_WAIT     */ TCP_LAST_ACK  | TCP_ACTION_FIN,
1759  /* TCP_LAST_ACK       */ TCP_LAST_ACK,
1760  /* TCP_LISTEN         */ TCP_CLOSE,
1761  /* TCP_CLOSING        */ TCP_CLOSING,
1762};
1763
1764static int tcp_close_state(struct sock *sk)
1765{
1766        int next = (int)new_state[sk->sk_state];
1767        int ns = next & TCP_STATE_MASK;
1768
1769        tcp_set_state(sk, ns);
1770
1771        return next & TCP_ACTION_FIN;
1772}
1773
1774/*
1775 *      Shutdown the sending side of a connection. Much like close except
1776 *      that we don't receive shut down or sock_set_flag(sk, SOCK_DEAD).
1777 */
1778
1779void tcp_shutdown(struct sock *sk, int how)
1780{
1781        /*      We need to grab some memory, and put together a FIN,
1782         *      and then put it into the queue to be sent.
1783         *              Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
1784         */
1785        if (!(how & SEND_SHUTDOWN))
1786                return;
1787
1788        /* If we've already sent a FIN, or it's a closed state, skip this. */
1789        if ((1 << sk->sk_state) &
1790            (TCPF_ESTABLISHED | TCPF_SYN_SENT |
1791             TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
1792                /* Clear out any half completed packets.  FIN if needed. */
1793                if (tcp_close_state(sk))
1794                        tcp_send_fin(sk);
1795        }
1796}
1797
1798void tcp_close(struct sock *sk, long timeout)
1799{
1800        struct sk_buff *skb;
1801        int data_was_unread = 0;
1802        int state;
1803
1804        lock_sock(sk);
1805        sk->sk_shutdown = SHUTDOWN_MASK;
1806
1807        if (sk->sk_state == TCP_LISTEN) {
1808                tcp_set_state(sk, TCP_CLOSE);
1809
1810                /* Special case. */
1811                inet_csk_listen_stop(sk);
1812
1813                goto adjudge_to_death;
1814        }
1815
1816        /*  We need to flush the recv. buffs.  We do this only on the
1817         *  descriptor close, not protocol-sourced closes, because the
1818         *  reader process may not have drained the data yet!
1819         */
1820        while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
1821                u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq -
1822                          tcp_hdr(skb)->fin;
1823                data_was_unread += len;
1824                __kfree_skb(skb);
1825        }
1826
1827        sk_mem_reclaim(sk);
1828
1829        /* As outlined in RFC 2525, section 2.17, we send a RST here because
1830         * data was lost. To witness the awful effects of the old behavior of
1831         * always doing a FIN, run an older 2.1.x kernel or 2.0.x, start a bulk
1832         * GET in an FTP client, suspend the process, wait for the client to
1833         * advertise a zero window, then kill -9 the FTP client, wheee...
1834         * Note: timeout is always zero in such a case.
1835         */
1836        if (data_was_unread) {
1837                /* Unread data was tossed, zap the connection. */
1838                NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPABORTONCLOSE);
1839                tcp_set_state(sk, TCP_CLOSE);
1840                tcp_send_active_reset(sk, GFP_KERNEL);
1841        } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
1842                /* Check zero linger _after_ checking for unread data. */
1843                sk->sk_prot->disconnect(sk, 0);
1844                NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
1845        } else if (tcp_close_state(sk)) {
1846                /* We FIN if the application ate all the data before
1847                 * zapping the connection.
1848                 */
1849
1850                /* RED-PEN. Formally speaking, we have broken TCP state
1851                 * machine. State transitions:
1852                 *
1853                 * TCP_ESTABLISHED -> TCP_FIN_WAIT1
1854                 * TCP_SYN_RECV -> TCP_FIN_WAIT1 (forget it, it's impossible)
1855                 * TCP_CLOSE_WAIT -> TCP_LAST_ACK
1856                 *
1857                 * are legal only when FIN has been sent (i.e. in window),
1858                 * rather than queued out of window. Purists blame.
1859                 *
1860                 * F.e. "RFC state" is ESTABLISHED,
1861                 * if Linux state is FIN-WAIT-1, but FIN is still not sent.
1862                 *
1863                 * The visible declinations are that sometimes
1864                 * we enter time-wait state, when it is not required really
1865                 * (harmless), do not send active resets, when they are
1866                 * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when
1867                 * they look as CLOSING or LAST_ACK for Linux)
1868                 * Probably, I missed some more holelets.
1869                 *                                              --ANK
1870                 */
1871                tcp_send_fin(sk);
1872        }
1873
1874        sk_stream_wait_close(sk, timeout);
1875
1876adjudge_to_death:
1877        state = sk->sk_state;
1878        sock_hold(sk);
1879        sock_orphan(sk);
1880
1881        /* It is the last release_sock in its life. It will remove backlog. */
1882        release_sock(sk);
1883
1884
1885        /* Now socket is owned by kernel and we acquire BH lock
1886           to finish close. No need to check for user refs.
1887         */
1888        local_bh_disable();
1889        bh_lock_sock(sk);
1890        WARN_ON(sock_owned_by_user(sk));
1891
1892        percpu_counter_inc(sk->sk_prot->orphan_count);
1893
1894        /* Have we already been destroyed by a softirq or backlog? */
1895        if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
1896                goto out;
1897
1898        /*      This is a (useful) BSD violating of the RFC. There is a
1899         *      problem with TCP as specified in that the other end could
1900         *      keep a socket open forever with no application left this end.
1901         *      We use a 3 minute timeout (about the same as BSD) then kill
1902         *      our end. If they send after that then tough - BUT: long enough
1903         *      that we won't make the old 4*rto = almost no time - whoops
1904         *      reset mistake.
1905         *
1906         *      Nope, it was not mistake. It is really desired behaviour
1907         *      f.e. on http servers, when such sockets are useless, but
1908         *      consume significant resources. Let's do it with special
1909         *      linger2 option.                                 --ANK
1910         */
1911
1912        if (sk->sk_state == TCP_FIN_WAIT2) {
1913                struct tcp_sock *tp = tcp_sk(sk);
1914                if (tp->linger2 < 0) {
1915                        tcp_set_state(sk, TCP_CLOSE);
1916                        tcp_send_active_reset(sk, GFP_ATOMIC);
1917                        NET_INC_STATS_BH(sock_net(sk),
1918                                        LINUX_MIB_TCPABORTONLINGER);
1919                } else {
1920                        const int tmo = tcp_fin_time(sk);
1921
1922                        if (tmo > TCP_TIMEWAIT_LEN) {
1923                                inet_csk_reset_keepalive_timer(sk,
1924                                                tmo - TCP_TIMEWAIT_LEN);
1925                        } else {
1926                                tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
1927                                goto out;
1928                        }
1929                }
1930        }
1931        if (sk->sk_state != TCP_CLOSE) {
1932                int orphan_count = percpu_counter_read_positive(
1933                                                sk->sk_prot->orphan_count);
1934
1935                sk_mem_reclaim(sk);
1936                if (tcp_too_many_orphans(sk, orphan_count)) {
1937                        if (net_ratelimit())
1938                                printk(KERN_INFO "TCP: too many of orphaned "
1939                                       "sockets\n");
1940                        tcp_set_state(sk, TCP_CLOSE);
1941                        tcp_send_active_reset(sk, GFP_ATOMIC);
1942                        NET_INC_STATS_BH(sock_net(sk),
1943                                        LINUX_MIB_TCPABORTONMEMORY);
1944                }
1945        }
1946
1947        if (sk->sk_state == TCP_CLOSE)
1948                inet_csk_destroy_sock(sk);
1949        /* Otherwise, socket is reprieved until protocol close. */
1950
1951out:
1952        bh_unlock_sock(sk);
1953        local_bh_enable();
1954        sock_put(sk);
1955}
1956
1957/* These states need RST on ABORT according to RFC793 */
1958
1959static inline int tcp_need_reset(int state)
1960{
1961        return (1 << state) &
1962               (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
1963                TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
1964}
1965
1966int tcp_disconnect(struct sock *sk, int flags)
1967{
1968        struct inet_sock *inet = inet_sk(sk);
1969        struct inet_connection_sock *icsk = inet_csk(sk);
1970        struct tcp_sock *tp = tcp_sk(sk);
1971        int err = 0;
1972        int old_state = sk->sk_state;
1973
1974        if (old_state != TCP_CLOSE)
1975                tcp_set_state(sk, TCP_CLOSE);
1976
1977        /* ABORT function of RFC793 */
1978        if (old_state == TCP_LISTEN) {
1979                inet_csk_listen_stop(sk);
1980        } else if (tcp_need_reset(old_state) ||
1981                   (tp->snd_nxt != tp->write_seq &&
1982                    (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
1983                /* The last check adjusts for discrepancy of Linux wrt. RFC
1984                 * states
1985                 */
1986                tcp_send_active_reset(sk, gfp_any());
1987                sk->sk_err = ECONNRESET;
1988        } else if (old_state == TCP_SYN_SENT)
1989                sk->sk_err = ECONNRESET;
1990
1991        tcp_clear_xmit_timers(sk);
1992        __skb_queue_purge(&sk->sk_receive_queue);
1993        tcp_write_queue_purge(sk);
1994        __skb_queue_purge(&tp->out_of_order_queue);
1995#ifdef CONFIG_NET_DMA
1996        __skb_queue_purge(&sk->sk_async_wait_queue);
1997#endif
1998
1999        inet->dport = 0;
2000
2001        if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
2002                inet_reset_saddr(sk);
2003
2004        sk->sk_shutdown = 0;
2005        sock_reset_flag(sk, SOCK_DONE);
2006        tp->srtt = 0;
2007        if ((tp->write_seq += tp->max_window + 2) == 0)
2008                tp->write_seq = 1;
2009        icsk->icsk_backoff = 0;
2010        tp->snd_cwnd = 2;
2011        icsk->icsk_probes_out = 0;
2012        tp->packets_out = 0;
2013        tp->snd_ssthresh = 0x7fffffff;
2014        tp->snd_cwnd_cnt = 0;
2015        tp->bytes_acked = 0;
2016        tcp_set_ca_state(sk, TCP_CA_Open);
2017        tcp_clear_retrans(tp);
2018        inet_csk_delack_init(sk);
2019        tcp_init_send_head(sk);
2020        memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
2021        __sk_dst_reset(sk);
2022
2023        WARN_ON(inet->num && !icsk->icsk_bind_hash);
2024
2025        sk->sk_error_report(sk);
2026        return err;
2027}
2028
2029/*
2030 *      Socket option code for TCP.
2031 */
2032static int do_tcp_setsockopt(struct sock *sk, int level,
2033                int optname, char __user *optval, int optlen)
2034{
2035        struct tcp_sock *tp = tcp_sk(sk);
2036        struct inet_connection_sock *icsk = inet_csk(sk);
2037        int val;
2038        int err = 0;
2039
2040        /* This is a string value all the others are int's */
2041        if (optname == TCP_CONGESTION) {
2042                char name[TCP_CA_NAME_MAX];
2043
2044                if (optlen < 1)
2045                        return -EINVAL;
2046
2047                val = strncpy_from_user(name, optval,
2048                                        min(TCP_CA_NAME_MAX-1, optlen));
2049                if (val < 0)
2050                        return -EFAULT;
2051                name[val] = 0;
2052
2053                lock_sock(sk);
2054                err = tcp_set_congestion_control(sk, name);
2055                release_sock(sk);
2056                return err;
2057        }
2058
2059        if (optlen < sizeof(int))
2060                return -EINVAL;
2061
2062        if (get_user(val, (int __user *)optval))
2063                return -EFAULT;
2064
2065        lock_sock(sk);
2066
2067        switch (optname) {
2068        case TCP_MAXSEG:
2069                /* Values greater than interface MTU won't take effect. However
2070                 * at the point when this call is done we typically don't yet
2071                 * know which interface is going to be used */
2072                if (val < 8 || val > MAX_TCP_WINDOW) {
2073                        err = -EINVAL;
2074                        break;
2075                }
2076                tp->rx_opt.user_mss = val;
2077                break;
2078
2079        case TCP_NODELAY:
2080                if (val) {
2081                        /* TCP_NODELAY is weaker than TCP_CORK, so that
2082                         * this option on corked socket is remembered, but
2083                         * it is not activated until cork is cleared.
2084                         *
2085                         * However, when TCP_NODELAY is set we make
2086                         * an explicit push, which overrides even TCP_CORK
2087                         * for currently queued segments.
2088                         */
2089                        tp->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
2090                        tcp_push_pending_frames(sk);
2091                } else {
2092                        tp->nonagle &= ~TCP_NAGLE_OFF;
2093                }
2094                break;
2095
2096        case TCP_CORK:
2097                /* When set indicates to always queue non-full frames.
2098                 * Later the user clears this option and we transmit
2099                 * any pending partial frames in the queue.  This is
2100                 * meant to be used alongside sendfile() to get properly
2101                 * filled frames when the user (for example) must write
2102                 * out headers with a write() call first and then use
2103                 * sendfile to send out the data parts.
2104                 *
2105                 * TCP_CORK can be set together with TCP_NODELAY and it is
2106                 * stronger than TCP_NODELAY.
2107                 */
2108                if (val) {
2109                        tp->nonagle |= TCP_NAGLE_CORK;
2110                } else {
2111                        tp->nonagle &= ~TCP_NAGLE_CORK;
2112                        if (tp->nonagle&TCP_NAGLE_OFF)
2113                                tp->nonagle |= TCP_NAGLE_PUSH;
2114                        tcp_push_pending_frames(sk);
2115                }
2116                break;
2117
2118        case TCP_KEEPIDLE:
2119                if (val < 1 || val > MAX_TCP_KEEPIDLE)
2120                        err = -EINVAL;
2121                else {
2122                        tp->keepalive_time = val * HZ;
2123                        if (sock_flag(sk, SOCK_KEEPOPEN) &&
2124                            !((1 << sk->sk_state) &
2125                              (TCPF_CLOSE | TCPF_LISTEN))) {
2126                                __u32 elapsed = tcp_time_stamp - tp->rcv_tstamp;
2127                                if (tp->keepalive_time > elapsed)
2128                                        elapsed = tp->keepalive_time - elapsed;
2129                                else
2130                                        elapsed = 0;
2131                                inet_csk_reset_keepalive_timer(sk, elapsed);
2132                        }
2133                }
2134                break;
2135        case TCP_KEEPINTVL:
2136                if (val < 1 || val > MAX_TCP_KEEPINTVL)
2137                        err = -EINVAL;
2138                else
2139                        tp->keepalive_intvl = val * HZ;
2140                break;
2141        case TCP_KEEPCNT:
2142                if (val < 1 || val > MAX_TCP_KEEPCNT)
2143                        err = -EINVAL;
2144                else
2145                        tp->keepalive_probes = val;
2146                break;
2147        case TCP_SYNCNT:
2148                if (val < 1 || val > MAX_TCP_SYNCNT)
2149                        err = -EINVAL;
2150                else
2151                        icsk->icsk_syn_retries = val;
2152                break;
2153
2154        case TCP_LINGER2:
2155                if (val < 0)
2156                        tp->linger2 = -1;
2157                else if (val > sysctl_tcp_fin_timeout / HZ)
2158                        tp->linger2 = 0;
2159                else
2160                        tp->linger2 = val * HZ;
2161                break;
2162
2163        case TCP_DEFER_ACCEPT:
2164                icsk->icsk_accept_queue.rskq_defer_accept = 0;
2165                if (val > 0) {
2166                        /* Translate value in seconds to number of
2167                         * retransmits */
2168                        while (icsk->icsk_accept_queue.rskq_defer_accept < 32 &&
2169                               val > ((TCP_TIMEOUT_INIT / HZ) <<
2170                                       icsk->icsk_accept_queue.rskq_defer_accept))
2171                                icsk->icsk_accept_queue.rskq_defer_accept++;
2172                        icsk->icsk_accept_queue.rskq_defer_accept++;
2173                }
2174                break;
2175
2176        case TCP_WINDOW_CLAMP:
2177                if (!val) {
2178                        if (sk->sk_state != TCP_CLOSE) {
2179                                err = -EINVAL;
2180                                break;
2181                        }
2182                        tp->window_clamp = 0;
2183                } else
2184                        tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
2185                                                SOCK_MIN_RCVBUF / 2 : val;
2186                break;
2187
2188        case TCP_QUICKACK:
2189                if (!val) {
2190                        icsk->icsk_ack.pingpong = 1;
2191                } else {
2192                        icsk->icsk_ack.pingpong = 0;
2193                        if ((1 << sk->sk_state) &
2194                            (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
2195                            inet_csk_ack_scheduled(sk)) {
2196                                icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
2197                                tcp_cleanup_rbuf(sk, 1);
2198                                if (!(val & 1))
2199                                        icsk->icsk_ack.pingpong = 1;
2200                        }
2201                }
2202                break;
2203
2204#ifdef CONFIG_TCP_MD5SIG
2205        case TCP_MD5SIG:
2206                /* Read the IP->Key mappings from userspace */
2207                err = tp->af_specific->md5_parse(sk, optval, optlen);
2208                break;
2209#endif
2210
2211        default:
2212                err = -ENOPROTOOPT;
2213                break;
2214        }
2215
2216        release_sock(sk);
2217        return err;
2218}
2219
2220int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
2221                   int optlen)
2222{
2223        struct inet_connection_sock *icsk = inet_csk(sk);
2224
2225        if (level != SOL_TCP)
2226                return icsk->icsk_af_ops->setsockopt(sk, level, optname,
2227                                                     optval, optlen);
2228        return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2229}
2230
2231#ifdef CONFIG_COMPAT
2232int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
2233                          char __user *optval, int optlen)
2234{
2235        if (level != SOL_TCP)
2236                return inet_csk_compat_setsockopt(sk, level, optname,
2237                                                  optval, optlen);
2238        return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2239}
2240
2241EXPORT_SYMBOL(compat_tcp_setsockopt);
2242#endif
2243
2244/* Return information about state of tcp endpoint in API format. */
2245void tcp_get_info(struct sock *sk, struct tcp_info *info)
2246{
2247        struct tcp_sock *tp = tcp_sk(sk);
2248        const struct inet_connection_sock *icsk = inet_csk(sk);
2249        u32 now = tcp_time_stamp;
2250
2251        memset(info, 0, sizeof(*info));
2252
2253        info->tcpi_state = sk->sk_state;
2254        info->tcpi_ca_state = icsk->icsk_ca_state;
2255        info->tcpi_retransmits = icsk->icsk_retransmits;
2256        info->tcpi_probes = icsk->icsk_probes_out;
2257        info->tcpi_backoff = icsk->icsk_backoff;
2258
2259        if (tp->rx_opt.tstamp_ok)
2260                info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
2261        if (tcp_is_sack(tp))
2262                info->tcpi_options |= TCPI_OPT_SACK;
2263        if (tp->rx_opt.wscale_ok) {
2264                info->tcpi_options |= TCPI_OPT_WSCALE;
2265                info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
2266                info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
2267        }
2268
2269        if (tp->ecn_flags&TCP_ECN_OK)
2270                info->tcpi_options |= TCPI_OPT_ECN;
2271
2272        info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
2273        info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
2274        info->tcpi_snd_mss = tp->mss_cache;
2275        info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
2276
2277        if (sk->sk_state == TCP_LISTEN) {
2278                info->tcpi_unacked = sk->sk_ack_backlog;
2279                info->tcpi_sacked = sk->sk_max_ack_backlog;
2280        } else {
2281                info->tcpi_unacked = tp->packets_out;
2282                info->tcpi_sacked = tp->sacked_out;
2283        }
2284        info->tcpi_lost = tp->lost_out;
2285        info->tcpi_retrans = tp->retrans_out;
2286        info->tcpi_fackets = tp->fackets_out;
2287
2288        info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
2289        info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
2290        info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
2291
2292        info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
2293        info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
2294        info->tcpi_rtt = jiffies_to_usecs(tp->srtt)>>3;
2295        info->tcpi_rttvar = jiffies_to_usecs(tp->mdev)>>2;
2296        info->tcpi_snd_ssthresh = tp->snd_ssthresh;
2297        info->tcpi_snd_cwnd = tp->snd_cwnd;
2298        info->tcpi_advmss = tp->advmss;
2299        info->tcpi_reordering = tp->reordering;
2300
2301        info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3;
2302        info->tcpi_rcv_space = tp->rcvq_space.space;
2303
2304        info->tcpi_total_retrans = tp->total_retrans;
2305}
2306
2307EXPORT_SYMBOL_GPL(tcp_get_info);
2308
2309static int do_tcp_getsockopt(struct sock *sk, int level,
2310                int optname, char __user *optval, int __user *optlen)
2311{
2312        struct inet_connection_sock *icsk = inet_csk(sk);
2313        struct tcp_sock *tp = tcp_sk(sk);
2314        int val, len;
2315
2316        if (get_user(len, optlen))
2317                return -EFAULT;
2318
2319        len = min_t(unsigned int, len, sizeof(int));
2320
2321        if (len < 0)
2322                return -EINVAL;
2323
2324        switch (optname) {
2325        case TCP_MAXSEG:
2326                val = tp->mss_cache;
2327                if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
2328                        val = tp->rx_opt.user_mss;
2329                break;
2330        case TCP_NODELAY:
2331                val = !!(tp->nonagle&TCP_NAGLE_OFF);
2332                break;
2333        case TCP_CORK:
2334                val = !!(tp->nonagle&TCP_NAGLE_CORK);
2335                break;
2336        case TCP_KEEPIDLE:
2337                val = (tp->keepalive_time ? : sysctl_tcp_keepalive_time) / HZ;
2338                break;
2339        case TCP_KEEPINTVL:
2340                val = (tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl) / HZ;
2341                break;
2342        case TCP_KEEPCNT:
2343                val = tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
2344                break;
2345        case TCP_SYNCNT:
2346                val = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
2347                break;
2348        case TCP_LINGER2:
2349                val = tp->linger2;
2350                if (val >= 0)
2351                        val = (val ? : sysctl_tcp_fin_timeout) / HZ;
2352                break;
2353        case TCP_DEFER_ACCEPT:
2354                val = !icsk->icsk_accept_queue.rskq_defer_accept ? 0 :
2355                        ((TCP_TIMEOUT_INIT / HZ) << (icsk->icsk_accept_queue.rskq_defer_accept - 1));
2356                break;
2357        case TCP_WINDOW_CLAMP:
2358                val = tp->window_clamp;
2359                break;
2360        case TCP_INFO: {
2361                struct tcp_info info;
2362
2363                if (get_user(len, optlen))
2364                        return -EFAULT;
2365
2366                tcp_get_info(sk, &info);
2367
2368                len = min_t(unsigned int, len, sizeof(info));
2369                if (put_user(len, optlen))
2370                        return -EFAULT;
2371                if (copy_to_user(optval, &info, len))
2372                        return -EFAULT;
2373                return 0;
2374        }
2375        case TCP_QUICKACK:
2376                val = !icsk->icsk_ack.pingpong;
2377                break;
2378
2379        case TCP_CONGESTION:
2380                if (get_user(len, optlen))
2381                        return -EFAULT;
2382                len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
2383                if (put_user(len, optlen))
2384                        return -EFAULT;
2385                if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
2386                        return -EFAULT;
2387                return 0;
2388        default:
2389                return -ENOPROTOOPT;
2390        }
2391
2392        if (put_user(len, optlen))
2393                return -EFAULT;
2394        if (copy_to_user(optval, &val, len))
2395                return -EFAULT;
2396        return 0;
2397}
2398
2399int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
2400                   int __user *optlen)
2401{
2402        struct inet_connection_sock *icsk = inet_csk(sk);
2403
2404        if (level != SOL_TCP)
2405                return icsk->icsk_af_ops->getsockopt(sk, level, optname,
2406                                                     optval, optlen);
2407        return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2408}
2409
2410#ifdef CONFIG_COMPAT
2411int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
2412                          char __user *optval, int __user *optlen)
2413{
2414        if (level != SOL_TCP)
2415                return inet_csk_compat_getsockopt(sk, level, optname,
2416                                                  optval, optlen);
2417        return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2418}
2419
2420EXPORT_SYMBOL(compat_tcp_getsockopt);
2421#endif
2422
2423struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int features)
2424{
2425        struct sk_buff *segs = ERR_PTR(-EINVAL);
2426        struct tcphdr *th;
2427        unsigned thlen;
2428        unsigned int seq;
2429        __be32 delta;
2430        unsigned int oldlen;
2431        unsigned int mss;
2432
2433        if (!pskb_may_pull(skb, sizeof(*th)))
2434                goto out;
2435
2436        th = tcp_hdr(skb);
2437        thlen = th->doff * 4;
2438        if (thlen < sizeof(*th))
2439                goto out;
2440
2441        if (!pskb_may_pull(skb, thlen))
2442                goto out;
2443
2444        oldlen = (u16)~skb->len;
2445        __skb_pull(skb, thlen);
2446
2447        mss = skb_shinfo(skb)->gso_size;
2448        if (unlikely(skb->len <= mss))
2449                goto out;
2450
2451        if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
2452                /* Packet is from an untrusted source, reset gso_segs. */
2453                int type = skb_shinfo(skb)->gso_type;
2454
2455                if (unlikely(type &
2456                             ~(SKB_GSO_TCPV4 |
2457                               SKB_GSO_DODGY |
2458                               SKB_GSO_TCP_ECN |
2459                               SKB_GSO_TCPV6 |
2460                               0) ||
2461                             !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))))
2462                        goto out;
2463
2464                skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
2465
2466                segs = NULL;
2467                goto out;
2468        }
2469
2470        segs = skb_segment(skb, features);
2471        if (IS_ERR(segs))
2472                goto out;
2473
2474        delta = htonl(oldlen + (thlen + mss));
2475
2476        skb = segs;
2477        th = tcp_hdr(skb);
2478        seq = ntohl(th->seq);
2479
2480        do {
2481                th->fin = th->psh = 0;
2482
2483                th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
2484                                       (__force u32)delta));
2485                if (skb->ip_summed != CHECKSUM_PARTIAL)
2486                        th->check =
2487                             csum_fold(csum_partial(skb_transport_header(skb),
2488                                                    thlen, skb->csum));
2489
2490                seq += mss;
2491                skb = skb->next;
2492                th = tcp_hdr(skb);
2493
2494                th->seq = htonl(seq);
2495                th->cwr = 0;
2496        } while (skb->next);
2497
2498        delta = htonl(oldlen + (skb->tail - skb->transport_header) +
2499                      skb->data_len);
2500        th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
2501                                (__force u32)delta));
2502        if (skb->ip_summed != CHECKSUM_PARTIAL)
2503                th->check = csum_fold(csum_partial(skb_transport_header(skb),
2504                                                   thlen, skb->csum));
2505
2506out:
2507        return segs;
2508}
2509EXPORT_SYMBOL(tcp_tso_segment);
2510
2511struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
2512{
2513        struct sk_buff **pp = NULL;
2514        struct sk_buff *p;
2515        struct tcphdr *th;
2516        struct tcphdr *th2;
2517        unsigned int len;
2518        unsigned int thlen;
2519        unsigned int flags;
2520        unsigned int mss = 1;
2521        int flush = 1;
2522        int i;
2523
2524        th = skb_gro_header(skb, sizeof(*th));
2525        if (unlikely(!th))
2526                goto out;
2527
2528        thlen = th->doff * 4;
2529        if (thlen < sizeof(*th))
2530                goto out;
2531
2532        th = skb_gro_header(skb, thlen);
2533        if (unlikely(!th))
2534                goto out;
2535
2536        skb_gro_pull(skb, thlen);
2537
2538        len = skb_gro_len(skb);
2539        flags = tcp_flag_word(th);
2540
2541        for (; (p = *head); head = &p->next) {
2542                if (!NAPI_GRO_CB(p)->same_flow)
2543                        continue;
2544
2545                th2 = tcp_hdr(p);
2546
2547                if ((th->source ^ th2->source) | (th->dest ^ th2->dest)) {
2548                        NAPI_GRO_CB(p)->same_flow = 0;
2549                        continue;
2550                }
2551
2552                goto found;
2553        }
2554
2555        goto out_check_final;
2556
2557found:
2558        flush = NAPI_GRO_CB(p)->flush;
2559        flush |= flags & TCP_FLAG_CWR;
2560        flush |= (flags ^ tcp_flag_word(th2)) &
2561                  ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH);
2562        flush |= (th->ack_seq ^ th2->ack_seq) | (th->window ^ th2->window);
2563        for (i = sizeof(*th); !flush && i < thlen; i += 4)
2564                flush |= *(u32 *)((u8 *)th + i) ^
2565                         *(u32 *)((u8 *)th2 + i);
2566
2567        mss = skb_shinfo(p)->gso_size;
2568
2569        flush |= (len > mss) | !len;
2570        flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
2571
2572        if (flush || skb_gro_receive(head, skb)) {
2573                mss = 1;
2574                goto out_check_final;
2575        }
2576
2577        p = *head;
2578        th2 = tcp_hdr(p);
2579        tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);
2580
2581out_check_final:
2582        flush = len < mss;
2583        flush |= flags & (TCP_FLAG_URG | TCP_FLAG_PSH | TCP_FLAG_RST |
2584                          TCP_FLAG_SYN | TCP_FLAG_FIN);
2585
2586        if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
2587                pp = head;
2588
2589out:
2590        NAPI_GRO_CB(skb)->flush |= flush;
2591
2592        return pp;
2593}
2594EXPORT_SYMBOL(tcp_gro_receive);
2595
2596int tcp_gro_complete(struct sk_buff *skb)
2597{
2598        struct tcphdr *th = tcp_hdr(skb);
2599
2600        skb->csum_start = skb_transport_header(skb) - skb->head;
2601        skb->csum_offset = offsetof(struct tcphdr, check);
2602        skb->ip_summed = CHECKSUM_PARTIAL;
2603
2604        skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
2605
2606        if (th->cwr)
2607                skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
2608
2609        return 0;
2610}
2611EXPORT_SYMBOL(tcp_gro_complete);
2612
2613#ifdef CONFIG_TCP_MD5SIG
2614static unsigned long tcp_md5sig_users;
2615static struct tcp_md5sig_pool **tcp_md5sig_pool;
2616static DEFINE_SPINLOCK(tcp_md5sig_pool_lock);
2617
2618static void __tcp_free_md5sig_pool(struct tcp_md5sig_pool **pool)
2619{
2620        int cpu;
2621        for_each_possible_cpu(cpu) {
2622                struct tcp_md5sig_pool *p = *per_cpu_ptr(pool, cpu);
2623                if (p) {
2624                        if (p->md5_desc.tfm)
2625                                crypto_free_hash(p->md5_desc.tfm);
2626                        kfree(p);
2627                        p = NULL;
2628                }
2629        }
2630        free_percpu(pool);
2631}
2632
2633void tcp_free_md5sig_pool(void)
2634{
2635        struct tcp_md5sig_pool **pool = NULL;
2636
2637        spin_lock_bh(&tcp_md5sig_pool_lock);
2638        if (--tcp_md5sig_users == 0) {
2639                pool = tcp_md5sig_pool;
2640                tcp_md5sig_pool = NULL;
2641        }
2642        spin_unlock_bh(&tcp_md5sig_pool_lock);
2643        if (pool)
2644                __tcp_free_md5sig_pool(pool);
2645}
2646
2647EXPORT_SYMBOL(tcp_free_md5sig_pool);
2648
2649static struct tcp_md5sig_pool **__tcp_alloc_md5sig_pool(void)
2650{
2651        int cpu;
2652        struct tcp_md5sig_pool **pool;
2653
2654        pool = alloc_percpu(struct tcp_md5sig_pool *);
2655        if (!pool)
2656                return NULL;
2657
2658        for_each_possible_cpu(cpu) {
2659                struct tcp_md5sig_pool *p;
2660                struct crypto_hash *hash;
2661
2662                p = kzalloc(sizeof(*p), GFP_KERNEL);
2663                if (!p)
2664                        goto out_free;
2665                *per_cpu_ptr(pool, cpu) = p;
2666
2667                hash = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
2668                if (!hash || IS_ERR(hash))
2669                        goto out_free;
2670
2671                p->md5_desc.tfm = hash;
2672        }
2673        return pool;
2674out_free:
2675        __tcp_free_md5sig_pool(pool);
2676        return NULL;
2677}
2678
2679struct tcp_md5sig_pool **tcp_alloc_md5sig_pool(void)
2680{
2681        struct tcp_md5sig_pool **pool;
2682        int alloc = 0;
2683
2684retry:
2685        spin_lock_bh(&tcp_md5sig_pool_lock);
2686        pool = tcp_md5sig_pool;
2687        if (tcp_md5sig_users++ == 0) {
2688                alloc = 1;
2689                spin_unlock_bh(&tcp_md5sig_pool_lock);
2690        } else if (!pool) {
2691                tcp_md5sig_users--;
2692                spin_unlock_bh(&tcp_md5sig_pool_lock);
2693                cpu_relax();
2694                goto retry;
2695        } else
2696                spin_unlock_bh(&tcp_md5sig_pool_lock);
2697
2698        if (alloc) {
2699                /* we cannot hold spinlock here because this may sleep. */
2700                struct tcp_md5sig_pool **p = __tcp_alloc_md5sig_pool();
2701                spin_lock_bh(&tcp_md5sig_pool_lock);
2702                if (!p) {
2703                        tcp_md5sig_users--;
2704                        spin_unlock_bh(&tcp_md5sig_pool_lock);
2705                        return NULL;
2706                }
2707                pool = tcp_md5sig_pool;
2708                if (pool) {
2709                        /* oops, it has already been assigned. */
2710                        spin_unlock_bh(&tcp_md5sig_pool_lock);
2711                        __tcp_free_md5sig_pool(p);
2712                } else {
2713                        tcp_md5sig_pool = pool = p;
2714                        spin_unlock_bh(&tcp_md5sig_pool_lock);
2715                }
2716        }
2717        return pool;
2718}
2719
2720EXPORT_SYMBOL(tcp_alloc_md5sig_pool);
2721
2722struct tcp_md5sig_pool *__tcp_get_md5sig_pool(int cpu)
2723{
2724        struct tcp_md5sig_pool **p;
2725        spin_lock_bh(&tcp_md5sig_pool_lock);
2726        p = tcp_md5sig_pool;
2727        if (p)
2728                tcp_md5sig_users++;
2729        spin_unlock_bh(&tcp_md5sig_pool_lock);
2730        return (p ? *per_cpu_ptr(p, cpu) : NULL);
2731}
2732
2733EXPORT_SYMBOL(__tcp_get_md5sig_pool);
2734
2735void __tcp_put_md5sig_pool(void)
2736{
2737        tcp_free_md5sig_pool();
2738}
2739
2740EXPORT_SYMBOL(__tcp_put_md5sig_pool);
2741
2742int tcp_md5_hash_header(struct tcp_md5sig_pool *hp,
2743                        struct tcphdr *th)
2744{
2745        struct scatterlist sg;
2746        int err;
2747
2748        __sum16 old_checksum = th->check;
2749        th->check = 0;
2750        /* options aren't included in the hash */
2751        sg_init_one(&sg, th, sizeof(struct tcphdr));
2752        err = crypto_hash_update(&hp->md5_desc, &sg, sizeof(struct tcphdr));
2753        th->check = old_checksum;
2754        return err;
2755}
2756
2757EXPORT_SYMBOL(tcp_md5_hash_header);
2758
2759int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *hp,
2760                          struct sk_buff *skb, unsigned header_len)
2761{
2762        struct scatterlist sg;
2763        const struct tcphdr *tp = tcp_hdr(skb);
2764        struct hash_desc *desc = &hp->md5_desc;
2765        unsigned i;
2766        const unsigned head_data_len = skb_headlen(skb) > header_len ?
2767                                       skb_headlen(skb) - header_len : 0;
2768        const struct skb_shared_info *shi = skb_shinfo(skb);
2769
2770        sg_init_table(&sg, 1);
2771
2772        sg_set_buf(&sg, ((u8 *) tp) + header_len, head_data_len);
2773        if (crypto_hash_update(desc, &sg, head_data_len))
2774                return 1;
2775
2776        for (i = 0; i < shi->nr_frags; ++i) {
2777                const struct skb_frag_struct *f = &shi->frags[i];
2778                sg_set_page(&sg, f->page, f->size, f->page_offset);
2779                if (crypto_hash_update(desc, &sg, f->size))
2780                        return 1;
2781        }
2782
2783        return 0;
2784}
2785
2786EXPORT_SYMBOL(tcp_md5_hash_skb_data);
2787
2788int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, struct tcp_md5sig_key *key)
2789{
2790        struct scatterlist sg;
2791
2792        sg_init_one(&sg, key->key, key->keylen);
2793        return crypto_hash_update(&hp->md5_desc, &sg, key->keylen);
2794}
2795
2796EXPORT_SYMBOL(tcp_md5_hash_key);
2797
2798#endif
2799
2800void tcp_done(struct sock *sk)
2801{
2802        if (sk->sk_state == TCP_SYN_SENT || sk->sk_state == TCP_SYN_RECV)
2803                TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_ATTEMPTFAILS);
2804
2805        tcp_set_state(sk, TCP_CLOSE);
2806        tcp_clear_xmit_timers(sk);
2807
2808        sk->sk_shutdown = SHUTDOWN_MASK;
2809
2810        if (!sock_flag(sk, SOCK_DEAD))
2811                sk->sk_state_change(sk);
2812        else
2813                inet_csk_destroy_sock(sk);
2814}
2815EXPORT_SYMBOL_GPL(tcp_done);
2816
2817extern struct tcp_congestion_ops tcp_reno;
2818
2819static __initdata unsigned long thash_entries;
2820static int __init set_thash_entries(char *str)
2821{
2822        if (!str)
2823                return 0;
2824        thash_entries = simple_strtoul(str, &str, 0);
2825        return 1;
2826}
2827__setup("thash_entries=", set_thash_entries);
2828
2829void __init tcp_init(void)
2830{
2831        struct sk_buff *skb = NULL;
2832        unsigned long nr_pages, limit;
2833        int order, i, max_share;
2834
2835        BUILD_BUG_ON(sizeof(struct tcp_skb_cb) > sizeof(skb->cb));
2836
2837        percpu_counter_init(&tcp_sockets_allocated, 0);
2838        percpu_counter_init(&tcp_orphan_count, 0);
2839        tcp_hashinfo.bind_bucket_cachep =
2840                kmem_cache_create("tcp_bind_bucket",
2841                                  sizeof(struct inet_bind_bucket), 0,
2842                                  SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
2843
2844        /* Size and allocate the main established and bind bucket
2845         * hash tables.
2846         *
2847         * The methodology is similar to that of the buffer cache.
2848         */
2849        tcp_hashinfo.ehash =
2850                alloc_large_system_hash("TCP established",
2851                                        sizeof(struct inet_ehash_bucket),
2852                                        thash_entries,
2853                                        (num_physpages >= 128 * 1024) ?
2854                                        13 : 15,
2855                                        0,
2856                                        &tcp_hashinfo.ehash_size,
2857                                        NULL,
2858                                        thash_entries ? 0 : 512 * 1024);
2859        tcp_hashinfo.ehash_size = 1 << tcp_hashinfo.ehash_size;
2860        for (i = 0; i < tcp_hashinfo.ehash_size; i++) {
2861                INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].chain, i);
2862                INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].twchain, i);
2863        }
2864        if (inet_ehash_locks_alloc(&tcp_hashinfo))
2865                panic("TCP: failed to alloc ehash_locks");
2866        tcp_hashinfo.bhash =
2867                alloc_large_system_hash("TCP bind",
2868                                        sizeof(struct inet_bind_hashbucket),
2869                                        tcp_hashinfo.ehash_size,
2870                                        (num_physpages >= 128 * 1024) ?
2871                                        13 : 15,
2872                                        0,
2873                                        &tcp_hashinfo.bhash_size,
2874                                        NULL,
2875                                        64 * 1024);
2876        tcp_hashinfo.bhash_size = 1 << tcp_hashinfo.bhash_size;
2877        for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
2878                spin_lock_init(&tcp_hashinfo.bhash[i].lock);
2879                INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
2880        }
2881
2882        /* Try to be a bit smarter and adjust defaults depending
2883         * on available memory.
2884         */
2885        for (order = 0; ((1 << order) << PAGE_SHIFT) <
2886                        (tcp_hashinfo.bhash_size * sizeof(struct inet_bind_hashbucket));
2887                        order++)
2888                ;
2889        if (order >= 4) {
2890                tcp_death_row.sysctl_max_tw_buckets = 180000;
2891                sysctl_tcp_max_orphans = 4096 << (order - 4);
2892                sysctl_max_syn_backlog = 1024;
2893        } else if (order < 3) {
2894                tcp_death_row.sysctl_max_tw_buckets >>= (3 - order);
2895                sysctl_tcp_max_orphans >>= (3 - order);
2896                sysctl_max_syn_backlog = 128;
2897        }
2898
2899        /* Set the pressure threshold to be a fraction of global memory that
2900         * is up to 1/2 at 256 MB, decreasing toward zero with the amount of
2901         * memory, with a floor of 128 pages.
2902         */
2903        nr_pages = totalram_pages - totalhigh_pages;
2904        limit = min(nr_pages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT);
2905        limit = (limit * (nr_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
2906        limit = max(limit, 128UL);
2907        sysctl_tcp_mem[0] = limit / 4 * 3;
2908        sysctl_tcp_mem[1] = limit;
2909        sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2;
2910
2911        /* Set per-socket limits to no more than 1/128 the pressure threshold */
2912        limit = ((unsigned long)sysctl_tcp_mem[1]) << (PAGE_SHIFT - 7);
2913        max_share = min(4UL*1024*1024, limit);
2914
2915        sysctl_tcp_wmem[0] = SK_MEM_QUANTUM;
2916        sysctl_tcp_wmem[1] = 16*1024;
2917        sysctl_tcp_wmem[2] = max(64*1024, max_share);
2918
2919        sysctl_tcp_rmem[0] = SK_MEM_QUANTUM;
2920        sysctl_tcp_rmem[1] = 87380;
2921        sysctl_tcp_rmem[2] = max(87380, max_share);
2922
2923        printk(KERN_INFO "TCP: Hash tables configured "
2924               "(established %d bind %d)\n",
2925               tcp_hashinfo.ehash_size, tcp_hashinfo.bhash_size);
2926
2927        tcp_register_congestion_control(&tcp_reno);
2928}
2929
2930EXPORT_SYMBOL(tcp_close);
2931EXPORT_SYMBOL(tcp_disconnect);
2932EXPORT_SYMBOL(tcp_getsockopt);
2933EXPORT_SYMBOL(tcp_ioctl);
2934EXPORT_SYMBOL(tcp_poll);
2935EXPORT_SYMBOL(tcp_read_sock);
2936EXPORT_SYMBOL(tcp_recvmsg);
2937EXPORT_SYMBOL(tcp_sendmsg);
2938EXPORT_SYMBOL(tcp_splice_read);
2939EXPORT_SYMBOL(tcp_sendpage);
2940EXPORT_SYMBOL(tcp_setsockopt);
2941EXPORT_SYMBOL(tcp_shutdown);
2942