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