net/ipv4/tcp.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              Implementation of the Transmission Control Protocol(TCP).
   7  *
   8  * Version:     $Id: tcp.c,v 1.216 2002/02/01 22:01:04 davem Exp $
   9  *
  10  * Authors:     Ross Biro
  11  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  12  *              Mark Evans, <evansmp@uhura.aston.ac.uk>
  13  *              Corey Minyard <wf-rch!minyard@relay.EU.net>
  14  *              Florian La Roche, <flla@stud.uni-sb.de>
  15  *              Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
  16  *              Linus Torvalds, <torvalds@cs.helsinki.fi>
  17  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  18  *              Matthew Dillon, <dillon@apollo.west.oic.com>
  19  *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
  20  *              Jorge Cwik, <jorge@laser.satlink.net>
  21  *
  22  * Fixes:
  23  *              Alan Cox        :       Numerous verify_area() calls
  24  *              Alan Cox        :       Set the ACK bit on a reset
  25  *              Alan Cox        :       Stopped it crashing if it closed while
  26  *                                      sk->inuse=1 and was trying to connect
  27  *                                      (tcp_err()).
  28  *              Alan Cox        :       All icmp error handling was broken
  29  *                                      pointers passed where wrong and the
  30  *                                      socket was looked up backwards. Nobody
  31  *                                      tested any icmp error code obviously.
  32  *              Alan Cox        :       tcp_err() now handled properly. It
  33  *                                      wakes people on errors. poll
  34  *                                      behaves and the icmp error race
  35  *                                      has gone by moving it into sock.c
  36  *              Alan Cox        :       tcp_send_reset() fixed to work for
  37  *                                      everything not just packets for
  38  *                                      unknown sockets.
  39  *              Alan Cox        :       tcp option processing.
  40  *              Alan Cox        :       Reset tweaked (still not 100%) [Had
  41  *                                      syn rule wrong]
  42  *              Herp Rosmanith  :       More reset fixes
  43  *              Alan Cox        :       No longer acks invalid rst frames.
  44  *                                      Acking any kind of RST is right out.
  45  *              Alan Cox        :       Sets an ignore me flag on an rst
  46  *                                      receive otherwise odd bits of prattle
  47  *                                      escape still
  48  *              Alan Cox        :       Fixed another acking RST frame bug.
  49  *                                      Should stop LAN workplace lockups.
  50  *              Alan Cox        :       Some tidyups using the new skb list
  51  *                                      facilities
  52  *              Alan Cox        :       sk->keepopen now seems to work
  53  *              Alan Cox        :       Pulls options out correctly on accepts
  54  *              Alan Cox        :       Fixed assorted sk->rqueue->next errors
  55  *              Alan Cox        :       PSH doesn't end a TCP read. Switched a
  56  *                                      bit to skb ops.
  57  *              Alan Cox        :       Tidied tcp_data to avoid a potential
  58  *                                      nasty.
  59  *              Alan Cox        :       Added some better commenting, as the
  60  *                                      tcp is hard to follow
  61  *              Alan Cox        :       Removed incorrect check for 20 * psh
  62  *      Michael O'Reilly        :       ack < copied bug fix.
  63  *      Johannes Stille         :       Misc tcp fixes (not all in yet).
  64  *              Alan Cox        :       FIN with no memory -> CRASH
  65  *              Alan Cox        :       Added socket option proto entries.
  66  *                                      Also added awareness of them to accept.
  67  *              Alan Cox        :       Added TCP options (SOL_TCP)
  68  *              Alan Cox        :       Switched wakeup calls to callbacks,
  69  *                                      so the kernel can layer network
  70  *                                      sockets.
  71  *              Alan Cox        :       Use ip_tos/ip_ttl settings.
  72  *              Alan Cox        :       Handle FIN (more) properly (we hope).
  73  *              Alan Cox        :       RST frames sent on unsynchronised
  74  *                                      state ack error.
  75  *              Alan Cox        :       Put in missing check for SYN bit.
  76  *              Alan Cox        :       Added tcp_select_window() aka NET2E
  77  *                                      window non shrink trick.
  78  *              Alan Cox        :       Added a couple of small NET2E timer
  79  *                                      fixes
  80  *              Charles Hedrick :       TCP fixes
  81  *              Toomas Tamm     :       TCP window fixes
  82  *              Alan Cox        :       Small URG fix to rlogin ^C ack fight
  83  *              Charles Hedrick :       Rewrote most of it to actually work
  84  *              Linus           :       Rewrote tcp_read() and URG handling
  85  *                                      completely
  86  *              Gerhard Koerting:       Fixed some missing timer handling
  87  *              Matthew Dillon  :       Reworked TCP machine states as per RFC
  88  *              Gerhard Koerting:       PC/TCP workarounds
  89  *              Adam Caldwell   :       Assorted timer/timing errors
  90  *              Matthew Dillon  :       Fixed another RST bug
  91  *              Alan Cox        :       Move to kernel side addressing changes.
  92  *              Alan Cox        :       Beginning work on TCP fastpathing
  93  *                                      (not yet usable)
  94  *              Arnt Gulbrandsen:       Turbocharged tcp_check() routine.
  95  *              Alan Cox        :       TCP fast path debugging
  96  *              Alan Cox        :       Window clamping
  97  *              Michael Riepe   :       Bug in tcp_check()
  98  *              Matt Dillon     :       More TCP improvements and RST bug fixes
  99  *              Matt Dillon     :       Yet more small nasties remove from the
 100  *                                      TCP code (Be very nice to this man if
 101  *                                      tcp finally works 100%) 8)
 102  *              Alan Cox        :       BSD accept semantics.
 103  *              Alan Cox        :       Reset on closedown bug.
 104  *      Peter De Schrijver      :       ENOTCONN check missing in tcp_sendto().
 105  *              Michael Pall    :       Handle poll() after URG properly in
 106  *                                      all cases.
 107  *              Michael Pall    :       Undo the last fix in tcp_read_urg()
 108  *                                      (multi URG PUSH broke rlogin).
 109  *              Michael Pall    :       Fix the multi URG PUSH problem in
 110  *                                      tcp_readable(), poll() after URG
 111  *                                      works now.
 112  *              Michael Pall    :       recv(...,MSG_OOB) never blocks in the
 113  *                                      BSD api.
 114  *              Alan Cox        :       Changed the semantics of sk->socket to
 115  *                                      fix a race and a signal problem with
 116  *                                      accept() and async I/O.
 117  *              Alan Cox        :       Relaxed the rules on tcp_sendto().
 118  *              Yury Shevchuk   :       Really fixed accept() blocking problem.
 119  *              Craig I. Hagan  :       Allow for BSD compatible TIME_WAIT for
 120  *                                      clients/servers which listen in on
 121  *                                      fixed ports.
 122  *              Alan Cox        :       Cleaned the above up and shrank it to
 123  *                                      a sensible code size.
 124  *              Alan Cox        :       Self connect lockup fix.
 125  *              Alan Cox        :       No connect to multicast.
 126  *              Ross Biro       :       Close unaccepted children on master
 127  *                                      socket close.
 128  *              Alan Cox        :       Reset tracing code.
 129  *              Alan Cox        :       Spurious resets on shutdown.
 130  *              Alan Cox        :       Giant 15 minute/60 second timer error
 131  *              Alan Cox        :       Small whoops in polling before an
 132  *                                      accept.
 133  *              Alan Cox        :       Kept the state trace facility since
 134  *                                      it's handy for debugging.
 135  *              Alan Cox        :       More reset handler fixes.
 136  *              Alan Cox        :       Started rewriting the code based on
 137  *                                      the RFC's for other useful protocol
 138  *                                      references see: Comer, KA9Q NOS, and
 139  *                                      for a reference on the difference
 140  *                                      between specifications and how BSD
 141  *                                      works see the 4.4lite source.
 142  *              A.N.Kuznetsov   :       Don't time wait on completion of tidy
 143  *                                      close.
 144  *              Linus Torvalds  :       Fin/Shutdown & copied_seq changes.
 145  *              Linus Torvalds  :       Fixed BSD port reuse to work first syn
 146  *              Alan Cox        :       Reimplemented timers as per the RFC
 147  *                                      and using multiple timers for sanity.
 148  *              Alan Cox        :       Small bug fixes, and a lot of new
 149  *                                      comments.
 150  *              Alan Cox        :       Fixed dual reader crash by locking
 151  *                                      the buffers (much like datagram.c)
 152  *              Alan Cox        :       Fixed stuck sockets in probe. A probe
 153  *                                      now gets fed up of retrying without
 154  *                                      (even a no space) answer.
 155  *              Alan Cox        :       Extracted closing code better
 156  *              Alan Cox        :       Fixed the closing state machine to
 157  *                                      resemble the RFC.
 158  *              Alan Cox        :       More 'per spec' fixes.
 159  *              Jorge Cwik      :       Even faster checksumming.
 160  *              Alan Cox        :       tcp_data() doesn't ack illegal PSH
 161  *                                      only frames. At least one pc tcp stack
 162  *                                      generates them.
 163  *              Alan Cox        :       Cache last socket.
 164  *              Alan Cox        :       Per route irtt.
 165  *              Matt Day        :       poll()->select() match BSD precisely on error
 166  *              Alan Cox        :       New buffers
 167  *              Marc Tamsky     :       Various sk->prot->retransmits and
 168  *                                      sk->retransmits misupdating fixed.
 169  *                                      Fixed tcp_write_timeout: stuck close,
 170  *                                      and TCP syn retries gets used now.
 171  *              Mark Yarvis     :       In tcp_read_wakeup(), don't send an
 172  *                                      ack if state is TCP_CLOSED.
 173  *              Alan Cox        :       Look up device on a retransmit - routes may
 174  *                                      change. Doesn't yet cope with MSS shrink right
 175  *                                      but it's a start!
 176  *              Marc Tamsky     :       Closing in closing fixes.
 177  *              Mike Shaver     :       RFC1122 verifications.
 178  *              Alan Cox        :       rcv_saddr errors.
 179  *              Alan Cox        :       Block double connect().
 180  *              Alan Cox        :       Small hooks for enSKIP.
 181  *              Alexey Kuznetsov:       Path MTU discovery.
 182  *              Alan Cox        :       Support soft errors.
 183  *              Alan Cox        :       Fix MTU discovery pathological case
 184  *                                      when the remote claims no mtu!
 185  *              Marc Tamsky     :       TCP_CLOSE fix.
 186  *              Colin (G3TNE)   :       Send a reset on syn ack replies in
 187  *                                      window but wrong (fixes NT lpd problems)
 188  *              Pedro Roque     :       Better TCP window handling, delayed ack.
 189  *              Joerg Reuter    :       No modification of locked buffers in
 190  *                                      tcp_do_retransmit()
 191  *              Eric Schenk     :       Changed receiver side silly window
 192  *                                      avoidance algorithm to BSD style
 193  *                                      algorithm. This doubles throughput
 194  *                                      against machines running Solaris,
 195  *                                      and seems to result in general
 196  *                                      improvement.
 197  *      Stefan Magdalinski      :       adjusted tcp_readable() to fix FIONREAD
 198  *      Willy Konynenberg       :       Transparent proxying support.
 199  *      Mike McLagan            :       Routing by source
 200  *              Keith Owens     :       Do proper merging with partial SKB's in
 201  *                                      tcp_do_sendmsg to avoid burstiness.
 202  *              Eric Schenk     :       Fix fast close down bug with
 203  *                                      shutdown() followed by close().
 204  *              Andi Kleen      :       Make poll agree with SIGIO
 205  *      Salvatore Sanfilippo    :       Support SO_LINGER with linger == 1 and
 206  *                                      lingertime == 0 (RFC 793 ABORT Call)
 207  *      Hirokazu Takahashi      :       Use copy_from_user() instead of
 208  *                                      csum_and_copy_from_user() if possible.
 209  *
 210  *              This program is free software; you can redistribute it and/or
 211  *              modify it under the terms of the GNU General Public License
 212  *              as published by the Free Software Foundation; either version
 213  *              2 of the License, or(at your option) any later version.
 214  *
 215  * Description of States:
 216  *
 217  *      TCP_SYN_SENT            sent a connection request, waiting for ack
 218  *
 219  *      TCP_SYN_RECV            received a connection request, sent ack,
 220  *                              waiting for final ack in three-way handshake.
 221  *
 222  *      TCP_ESTABLISHED         connection established
 223  *
 224  *      TCP_FIN_WAIT1           our side has shutdown, waiting to complete
 225  *                              transmission of remaining buffered data
 226  *
 227  *      TCP_FIN_WAIT2           all buffered data sent, waiting for remote
 228  *                              to shutdown
 229  *
 230  *      TCP_CLOSING             both sides have shutdown but we still have
 231  *                              data we have to finish sending
 232  *
 233  *      TCP_TIME_WAIT           timeout to catch resent junk before entering
 234  *                              closed, can only be entered from FIN_WAIT2
 235  *                              or CLOSING.  Required because the other end
 236  *                              may not have gotten our last ACK causing it
 237  *                              to retransmit the data packet (which we ignore)
 238  *
 239  *      TCP_CLOSE_WAIT          remote side has shutdown and is waiting for
 240  *                              us to finish writing our data and to shutdown
 241  *                              (we have to close() to move on to LAST_ACK)
 242  *
 243  *      TCP_LAST_ACK            out side has shutdown after remote has
 244  *                              shutdown.  There may still be data in our
 245  *                              buffer that we have to finish sending
 246  *
 247  *      TCP_CLOSE               socket is finished
 248  */
 249
 250 #include <linux/kernel.h>
 251 #include <linux/module.h>
 252 #include <linux/types.h>
 253 #include <linux/fcntl.h>
 254 #include <linux/poll.h>
 255 #include <linux/init.h>
 256 #include <linux/fs.h>
 257 #include <linux/skbuff.h>
 258 #include <linux/splice.h>
 259 #include <linux/net.h>
 260 #include <linux/socket.h>
 261 #include <linux/random.h>
 262 #include <linux/bootmem.h>
 263 #include <linux/cache.h>
 264 #include <linux/err.h>
 265 #include <linux/crypto.h>
 266
 267 #include <net/icmp.h>
 268 #include <net/tcp.h>
 269 #include <net/xfrm.h>
 270 #include <net/ip.h>
 271 #include <net/netdma.h>
 272 #include <net/sock.h>
 273
 274 #include <asm/uaccess.h>
 275 #include <asm/ioctls.h>
 276
 277 int sysctl_tcp_fin_timeout __read_mostly = TCP_FIN_TIMEOUT;
 278
 279 DEFINE_SNMP_STAT(struct tcp_mib, tcp_statistics) __read_mostly;
 280
 281 atomic_t tcp_orphan_count = ATOMIC_INIT(0);
 282
 283 EXPORT_SYMBOL_GPL(tcp_orphan_count);
 284
 285 int sysctl_tcp_mem[3] __read_mostly;
 286 int sysctl_tcp_wmem[3] __read_mostly;
 287 int sysctl_tcp_rmem[3] __read_mostly;
 288
 289 EXPORT_SYMBOL(sysctl_tcp_mem);
 290 EXPORT_SYMBOL(sysctl_tcp_rmem);
 291 EXPORT_SYMBOL(sysctl_tcp_wmem);
 292
 293 atomic_t tcp_memory_allocated;  /* Current allocated memory. */
 294 atomic_t tcp_sockets_allocated; /* Current number of TCP sockets. */
 295
 296 EXPORT_SYMBOL(tcp_memory_allocated);
 297 EXPORT_SYMBOL(tcp_sockets_allocated);
 298
 299 /*
 300  * TCP splice context
 301  */
 302 struct tcp_splice_state {
 303         struct pipe_inode_info *pipe;
 304         size_t len;
 305         unsigned int flags;
 306 };
 307
 308 /*
 309  * Pressure flag: try to collapse.
 310  * Technical note: it is used by multiple contexts non atomically.
 311  * All the __sk_mem_schedule() is of this nature: accounting
 312  * is strict, actions are advisory and have some latency.
 313  */
 314 int tcp_memory_pressure __read_mostly;
 315
 316 EXPORT_SYMBOL(tcp_memory_pressure);
 317
 318 void tcp_enter_memory_pressure(void)
 319 {
 320         if (!tcp_memory_pressure) {
 321                 NET_INC_STATS(LINUX_MIB_TCPMEMORYPRESSURES);
 322                 tcp_memory_pressure = 1;
 323         }
 324 }
 325
 326 EXPORT_SYMBOL(tcp_enter_memory_pressure);
 327
 328 /*
 329  *      Wait for a TCP event.
 330  *
 331  *      Note that we don't need to lock the socket, as the upper poll layers
 332  *      take care of normal races (between the test and the event) and we don't
 333  *      go look at any of the socket buffers directly.
 334  */
 335 unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
 336 {
 337         unsigned int mask;
 338         struct sock *sk = sock->sk;
 339         struct tcp_sock *tp = tcp_sk(sk);
 340
 341         poll_wait(file, sk->sk_sleep, wait);
 342         if (sk->sk_state == TCP_LISTEN)
 343                 return inet_csk_listen_poll(sk);
 344
 345         /* Socket is not locked. We are protected from async events
 346            by poll logic and correct handling of state changes
 347            made by another threads is impossible in any case.
 348          */
 349
 350         mask = 0;
 351         if (sk->sk_err)
 352                 mask = POLLERR;
 353
 354         /*
 355          * POLLHUP is certainly not done right. But poll() doesn't
 356          * have a notion of HUP in just one direction, and for a
 357          * socket the read side is more interesting.
 358          *
 359          * Some poll() documentation says that POLLHUP is incompatible
 360          * with the POLLOUT/POLLWR flags, so somebody should check this
 361          * all. But careful, it tends to be safer to return too many
 362          * bits than too few, and you can easily break real applications
 363          * if you don't tell them that something has hung up!
 364          *
 365          * Check-me.
 366          *
 367          * Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and
 368          * our fs/select.c). It means that after we received EOF,
 369          * poll always returns immediately, making impossible poll() on write()
 370          * in state CLOSE_WAIT. One solution is evident --- to set POLLHUP
 371          * if and only if shutdown has been made in both directions.
 372          * Actually, it is interesting to look how Solaris and DUX
 373          * solve this dilemma. I would prefer, if PULLHUP were maskable,
 374          * then we could set it on SND_SHUTDOWN. BTW examples given
 375          * in Stevens' books assume exactly this behaviour, it explains
 376          * why PULLHUP is incompatible with POLLOUT.    --ANK
 377          *
 378          * NOTE. Check for TCP_CLOSE is added. The goal is to prevent
 379          * blocking on fresh not-connected or disconnected socket. --ANK
 380          */
 381         if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == TCP_CLOSE)
 382                 mask |= POLLHUP;
 383         if (sk->sk_shutdown & RCV_SHUTDOWN)
 384                 mask |= POLLIN | POLLRDNORM | POLLRDHUP;
 385
 386         /* Connected? */
 387         if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV)) {
 388                 /* Potential race condition. If read of tp below will
 389                  * escape above sk->sk_state, we can be illegally awaken
 390                  * in SYN_* states. */
 391                 if ((tp->rcv_nxt != tp->copied_seq) &&
 392                     (tp->urg_seq != tp->copied_seq ||
 393                      tp->rcv_nxt != tp->copied_seq + 1 ||
 394                      sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data))
 395                         mask |= POLLIN | POLLRDNORM;
 396
 397                 if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
 398                         if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
 399                                 mask |= POLLOUT | POLLWRNORM;
 400                         } else {  /* send SIGIO later */
 401                                 set_bit(SOCK_ASYNC_NOSPACE,
 402                                         &sk->sk_socket->flags);
 403                                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 404
 405                                 /* Race breaker. If space is freed after
 406                                  * wspace test but before the flags are set,
 407                                  * IO signal will be lost.
 408                                  */
 409                                 if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk))
 410                                         mask |= POLLOUT | POLLWRNORM;
 411                         }
 412                 }
 413
 414                 if (tp->urg_data & TCP_URG_VALID)
 415                         mask |= POLLPRI;
 416         }
 417         return mask;
 418 }
 419
 420 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
 421 {
 422         struct tcp_sock *tp = tcp_sk(sk);
 423         int answ;
 424
 425         switch (cmd) {
 426         case SIOCINQ:
 427                 if (sk->sk_state == TCP_LISTEN)
 428                         return -EINVAL;
 429
 430                 lock_sock(sk);
 431                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
 432                         answ = 0;
 433                 else if (sock_flag(sk, SOCK_URGINLINE) ||
 434                          !tp->urg_data ||
 435                          before(tp->urg_seq, tp->copied_seq) ||
 436                          !before(tp->urg_seq, tp->rcv_nxt)) {
 437                         answ = tp->rcv_nxt - tp->copied_seq;
 438
 439                         /* Subtract 1, if FIN is in queue. */
 440                         if (answ && !skb_queue_empty(&sk->sk_receive_queue))
 441                                 answ -=
 442                        tcp_hdr((struct sk_buff *)sk->sk_receive_queue.prev)->fin;
 443                 } else
 444                         answ = tp->urg_seq - tp->copied_seq;
 445                 release_sock(sk);
 446                 break;
 447         case SIOCATMARK:
 448                 answ = tp->urg_data && tp->urg_seq == tp->copied_seq;
 449                 break;
 450         case SIOCOUTQ:
 451                 if (sk->sk_state == TCP_LISTEN)
 452                         return -EINVAL;
 453
 454                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
 455                         answ = 0;
 456                 else
 457                         answ = tp->write_seq - tp->snd_una;
 458                 break;
 459         default:
 460                 return -ENOIOCTLCMD;
 461         }
 462
 463         return put_user(answ, (int __user *)arg);
 464 }
 465
 466 static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
 467 {
 468         TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH;
 469         tp->pushed_seq = tp->write_seq;
 470 }
 471
 472 static inline int forced_push(struct tcp_sock *tp)
 473 {
 474         return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
 475 }
 476
 477 static inline void skb_entail(struct sock *sk, struct sk_buff *skb)
 478 {
 479         struct tcp_sock *tp = tcp_sk(sk);
 480         struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
 481
 482         skb->csum    = 0;
 483         tcb->seq     = tcb->end_seq = tp->write_seq;
 484         tcb->flags   = TCPCB_FLAG_ACK;
 485         tcb->sacked  = 0;
 486         skb_header_release(skb);
 487         tcp_add_write_queue_tail(sk, skb);
 488         sk->sk_wmem_queued += skb->truesize;
 489         sk_mem_charge(sk, skb->truesize);
 490         if (tp->nonagle & TCP_NAGLE_PUSH)
 491                 tp->nonagle &= ~TCP_NAGLE_PUSH;
 492 }
 493
 494 static inline void tcp_mark_urg(struct tcp_sock *tp, int flags,
 495                                 struct sk_buff *skb)
 496 {
 497         if (flags & MSG_OOB) {
 498                 tp->urg_mode = 1;
 499                 tp->snd_up = tp->write_seq;
 500         }
 501 }
 502
 503 static inline void tcp_push(struct sock *sk, int flags, int mss_now,
 504                             int nonagle)
 505 {
 506         struct tcp_sock *tp = tcp_sk(sk);
 507
 508         if (tcp_send_head(sk)) {
 509                 struct sk_buff *skb = tcp_write_queue_tail(sk);
 510                 if (!(flags & MSG_MORE) || forced_push(tp))
 511                         tcp_mark_push(tp, skb);
 512                 tcp_mark_urg(tp, flags, skb);
 513                 __tcp_push_pending_frames(sk, mss_now,
 514                                           (flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle);
 515         }
 516 }
 517
 518 static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
 519                                 unsigned int offset, size_t len)
 520 {
 521         struct tcp_splice_state *tss = rd_desc->arg.data;
 522
 523         return skb_splice_bits(skb, offset, tss->pipe, tss->len, tss->flags);
 524 }
 525
 526 static int __tcp_splice_read(struct sock *sk, struct tcp_splice_state *tss)
 527 {
 528         /* Store TCP splice context information in read_descriptor_t. */
 529         read_descriptor_t rd_desc = {
 530                 .arg.data = tss,
 531         };
 532
 533         return tcp_read_sock(sk, &rd_desc, tcp_splice_data_recv);
 534 }
 535
 536 /**
 537  *  tcp_splice_read - splice data from TCP socket to a pipe
 538  * @sock:       socket to splice from
 539  * @ppos:       position (not valid)
 540  * @pipe:       pipe to splice to
 541  * @len:        number of bytes to splice
 542  * @flags:      splice modifier flags
 543  *
 544  * Description:
 545  *    Will read pages from given socket and fill them into a pipe.
 546  *
 547  **/
 548 ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
 549                         struct pipe_inode_info *pipe, size_t len,
 550                         unsigned int flags)
 551 {
 552         struct sock *sk = sock->sk;
 553         struct tcp_splice_state tss = {
 554                 .pipe = pipe,
 555                 .len = len,
 556                 .flags = flags,
 557         };
 558         long timeo;
 559         ssize_t spliced;
 560         int ret;
 561
 562         /*
 563          * We can't seek on a socket input
 564          */
 565         if (unlikely(*ppos))
 566                 return -ESPIPE;
 567
 568         ret = spliced = 0;
 569
 570         lock_sock(sk);
 571
 572         timeo = sock_rcvtimeo(sk, flags & SPLICE_F_NONBLOCK);
 573         while (tss.len) {
 574                 ret = __tcp_splice_read(sk, &tss);
 575                 if (ret < 0)
 576                         break;
 577                 else if (!ret) {
 578                         if (spliced)
 579                                 break;
 580                         if (flags & SPLICE_F_NONBLOCK) {
 581                                 ret = -EAGAIN;
 582                                 break;
 583                         }
 584                         if (sock_flag(sk, SOCK_DONE))
 585                                 break;
 586                         if (sk->sk_err) {
 587                                 ret = sock_error(sk);
 588                                 break;
 589                         }
 590                         if (sk->sk_shutdown & RCV_SHUTDOWN)
 591                                 break;
 592                         if (sk->sk_state == TCP_CLOSE) {
 593                                 /*
 594                                  * This occurs when user tries to read
 595                                  * from never connected socket.
 596                                  */
 597                                 if (!sock_flag(sk, SOCK_DONE))
 598                                         ret = -ENOTCONN;
 599                                 break;
 600                         }
 601                         if (!timeo) {
 602                                 ret = -EAGAIN;
 603                                 break;
 604                         }
 605                         sk_wait_data(sk, &timeo);
 606                         if (signal_pending(current)) {
 607                                 ret = sock_intr_errno(timeo);
 608                                 break;
 609                         }
 610                         continue;
 611                 }
 612                 tss.len -= ret;
 613                 spliced += ret;
 614
 615                 release_sock(sk);
 616                 lock_sock(sk);
 617
 618                 if (sk->sk_err || sk->sk_state == TCP_CLOSE ||
 619                     (sk->sk_shutdown & RCV_SHUTDOWN) || !timeo ||
 620                     signal_pending(current))
 621                         break;
 622         }
 623
 624         release_sock(sk);
 625
 626         if (spliced)
 627                 return spliced;
 628
 629         return ret;
 630 }
 631
 632 struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp)
 633 {
 634         struct sk_buff *skb;
 635
 636         /* The TCP header must be at least 32-bit aligned.  */
 637         size = ALIGN(size, 4);
 638
 639         skb = alloc_skb_fclone(size + sk->sk_prot->max_header, gfp);
 640         if (skb) {
 641                 if (sk_wmem_schedule(sk, skb->truesize)) {
 642                         /*
 643                          * Make sure that we have exactly size bytes
 644                          * available to the caller, no more, no less.
 645                          */
 646                         skb_reserve(skb, skb_tailroom(skb) - size);
 647                         return skb;
 648                 }
 649                 __kfree_skb(skb);
 650         } else {
 651                 sk->sk_prot->enter_memory_pressure();
 652                 sk_stream_moderate_sndbuf(sk);
 653         }
 654         return NULL;
 655 }
 656
 657 static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset,
 658                          size_t psize, int flags)
 659 {
 660         struct tcp_sock *tp = tcp_sk(sk);
 661         int mss_now, size_goal;
 662         int err;
 663         ssize_t copied;
 664         long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 665
 666         /* Wait for a connection to finish. */
 667         if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
 668                 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
 669                         goto out_err;
 670
 671         clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 672
 673         mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
 674         size_goal = tp->xmit_size_goal;
 675         copied = 0;
 676
 677         err = -EPIPE;
 678         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 679                 goto do_error;
 680
 681         while (psize > 0) {
 682                 struct sk_buff *skb = tcp_write_queue_tail(sk);
 683                 struct page *page = pages[poffset / PAGE_SIZE];
 684                 int copy, i, can_coalesce;
 685                 int offset = poffset % PAGE_SIZE;
 686                 int size = min_t(size_t, psize, PAGE_SIZE - offset);
 687
 688                 if (!tcp_send_head(sk) || (copy = size_goal - skb->len) <= 0) {
 689 new_segment:
 690                         if (!sk_stream_memory_free(sk))
 691                                 goto wait_for_sndbuf;
 692
 693                         skb = sk_stream_alloc_skb(sk, 0, sk->sk_allocation);
 694                         if (!skb)
 695                                 goto wait_for_memory;
 696
 697                         skb_entail(sk, skb);
 698                         copy = size_goal;
 699                 }
 700
 701                 if (copy > size)
 702                         copy = size;
 703
 704                 i = skb_shinfo(skb)->nr_frags;
 705                 can_coalesce = skb_can_coalesce(skb, i, page, offset);
 706                 if (!can_coalesce && i >= MAX_SKB_FRAGS) {
 707                         tcp_mark_push(tp, skb);
 708                         goto new_segment;
 709                 }
 710                 if (!sk_wmem_schedule(sk, copy))
 711                         goto wait_for_memory;
 712
 713                 if (can_coalesce) {
 714                         skb_shinfo(skb)->frags[i - 1].size += copy;
 715                 } else {
 716                         get_page(page);
 717                         skb_fill_page_desc(skb, i, page, offset, copy);
 718                 }
 719
 720                 skb->len += copy;
 721                 skb->data_len += copy;
 722                 skb->truesize += copy;
 723                 sk->sk_wmem_queued += copy;
 724                 sk_mem_charge(sk, copy);
 725                 skb->ip_summed = CHECKSUM_PARTIAL;
 726                 tp->write_seq += copy;
 727                 TCP_SKB_CB(skb)->end_seq += copy;
 728                 skb_shinfo(skb)->gso_segs = 0;
 729
 730                 if (!copied)
 731                         TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
 732
 733                 copied += copy;
 734                 poffset += copy;
 735                 if (!(psize -= copy))
 736                         goto out;
 737
 738                 if (skb->len < size_goal || (flags & MSG_OOB))
 739                         continue;
 740
 741                 if (forced_push(tp)) {
 742                         tcp_mark_push(tp, skb);
 743                         __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
 744                 } else if (skb == tcp_send_head(sk))
 745                         tcp_push_one(sk, mss_now);
 746                 continue;
 747
 748 wait_for_sndbuf:
 749                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 750 wait_for_memory:
 751                 if (copied)
 752                         tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
 753
 754                 if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
 755                         goto do_error;
 756
 757                 mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
 758                 size_goal = tp->xmit_size_goal;
 759         }
 760
 761 out:
 762         if (copied)
 763                 tcp_push(sk, flags, mss_now, tp->nonagle);
 764         return copied;
 765
 766 do_error:
 767         if (copied)
 768                 goto out;
 769 out_err:
 770         return sk_stream_error(sk, flags, err);
 771 }
 772
 773 ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset,
 774                      size_t size, int flags)
 775 {
 776         ssize_t res;
 777         struct sock *sk = sock->sk;
 778
 779         if (!(sk->sk_route_caps & NETIF_F_SG) ||
 780             !(sk->sk_route_caps & NETIF_F_ALL_CSUM))
 781                 return sock_no_sendpage(sock, page, offset, size, flags);
 782
 783         lock_sock(sk);
 784         TCP_CHECK_TIMER(sk);
 785         res = do_tcp_sendpages(sk, &page, offset, size, flags);
 786         TCP_CHECK_TIMER(sk);
 787         release_sock(sk);
 788         return res;
 789 }
 790
 791 #define TCP_PAGE(sk)    (sk->sk_sndmsg_page)
 792 #define TCP_OFF(sk)     (sk->sk_sndmsg_off)
 793
 794 static inline int select_size(struct sock *sk)
 795 {
 796         struct tcp_sock *tp = tcp_sk(sk);
 797         int tmp = tp->mss_cache;
 798
 799         if (sk->sk_route_caps & NETIF_F_SG) {
 800                 if (sk_can_gso(sk))
 801                         tmp = 0;
 802                 else {
 803                         int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
 804
 805                         if (tmp >= pgbreak &&
 806                             tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
 807                                 tmp = pgbreak;
 808                 }
 809         }
 810
 811         return tmp;
 812 }
 813
 814 int tcp_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
 815                 size_t size)
 816 {
 817         struct sock *sk = sock->sk;
 818         struct iovec *iov;
 819         struct tcp_sock *tp = tcp_sk(sk);
 820         struct sk_buff *skb;
 821         int iovlen, flags;
 822         int mss_now, size_goal;
 823         int err, copied;
 824         long timeo;
 825
 826         lock_sock(sk);
 827         TCP_CHECK_TIMER(sk);
 828
 829         flags = msg->msg_flags;
 830         timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 831
 832         /* Wait for a connection to finish. */
 833         if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
 834                 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
 835                         goto out_err;
 836
 837         /* This should be in poll */
 838         clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 839
 840         mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
 841         size_goal = tp->xmit_size_goal;
 842
 843         /* Ok commence sending. */
 844         iovlen = msg->msg_iovlen;
 845         iov = msg->msg_iov;
 846         copied = 0;
 847
 848         err = -EPIPE;
 849         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 850                 goto do_error;
 851
 852         while (--iovlen >= 0) {
 853                 int seglen = iov->iov_len;
 854                 unsigned char __user *from = iov->iov_base;
 855
 856                 iov++;
 857
 858                 while (seglen > 0) {
 859                         int copy;
 860
 861                         skb = tcp_write_queue_tail(sk);
 862
 863                         if (!tcp_send_head(sk) ||
 864                             (copy = size_goal - skb->len) <= 0) {
 865
 866 new_segment:
 867                                 /* Allocate new segment. If the interface is SG,
 868                                  * allocate skb fitting to single page.
 869                                  */
 870                                 if (!sk_stream_memory_free(sk))
 871                                         goto wait_for_sndbuf;
 872
 873                                 skb = sk_stream_alloc_skb(sk, select_size(sk),
 874                                                 sk->sk_allocation);
 875                                 if (!skb)
 876                                         goto wait_for_memory;
 877
 878                                 /*
 879                                  * Check whether we can use HW checksum.
 880                                  */
 881                                 if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
 882                                         skb->ip_summed = CHECKSUM_PARTIAL;
 883
 884                                 skb_entail(sk, skb);
 885                                 copy = size_goal;
 886                         }
 887
 888                         /* Try to append data to the end of skb. */
 889                         if (copy > seglen)
 890                                 copy = seglen;
 891
 892                         /* Where to copy to? */
 893                         if (skb_tailroom(skb) > 0) {
 894                                 /* We have some space in skb head. Superb! */
 895                                 if (copy > skb_tailroom(skb))
 896                                         copy = skb_tailroom(skb);
 897                                 if ((err = skb_add_data(skb, from, copy)) != 0)
 898                                         goto do_fault;
 899                         } else {
 900                                 int merge = 0;
 901                                 int i = skb_shinfo(skb)->nr_frags;
 902                                 struct page *page = TCP_PAGE(sk);
 903                                 int off = TCP_OFF(sk);
 904
 905                                 if (skb_can_coalesce(skb, i, page, off) &&
 906                                     off != PAGE_SIZE) {
 907                                         /* We can extend the last page
 908                                          * fragment. */
 909                                         merge = 1;
 910                                 } else if (i == MAX_SKB_FRAGS ||
 911                                            (!i &&
 912                                            !(sk->sk_route_caps & NETIF_F_SG))) {
 913                                         /* Need to add new fragment and cannot
 914                                          * do this because interface is non-SG,
 915                                          * or because all the page slots are
 916                                          * busy. */
 917                                         tcp_mark_push(tp, skb);
 918                                         goto new_segment;
 919                                 } else if (page) {
 920                                         if (off == PAGE_SIZE) {
 921                                                 put_page(page);
 922                                                 TCP_PAGE(sk) = page = NULL;
 923                                                 off = 0;
 924                                         }
 925                                 } else
 926                                         off = 0;
 927
 928                                 if (copy > PAGE_SIZE - off)
 929                                         copy = PAGE_SIZE - off;
 930
 931                                 if (!sk_wmem_schedule(sk, copy))
 932                                         goto wait_for_memory;
 933
 934                                 if (!page) {
 935                                         /* Allocate new cache page. */
 936                                         if (!(page = sk_stream_alloc_page(sk)))
 937                                                 goto wait_for_memory;
 938                                 }
 939
 940                                 /* Time to copy data. We are close to
 941                                  * the end! */
 942                                 err = skb_copy_to_page(sk, from, skb, page,
 943                                                        off, copy);
 944                                 if (err) {
 945                                         /* If this page was new, give it to the
 946                                          * socket so it does not get leaked.
 947                                          */
 948                                         if (!TCP_PAGE(sk)) {
 949                                                 TCP_PAGE(sk) = page;
 950                                                 TCP_OFF(sk) = 0;
 951                                         }
 952                                         goto do_error;
 953                                 }
 954
 955                                 /* Update the skb. */
 956                                 if (merge) {
 957                                         skb_shinfo(skb)->frags[i - 1].size +=
 958                                                                         copy;
 959                                 } else {
 960                                         skb_fill_page_desc(skb, i, page, off, copy);
 961                                         if (TCP_PAGE(sk)) {
 962                                                 get_page(page);
 963                                         } else if (off + copy < PAGE_SIZE) {
 964                                                 get_page(page);
 965                                                 TCP_PAGE(sk) = page;
 966                                         }
 967                                 }
 968
 969                                 TCP_OFF(sk) = off + copy;
 970                         }
 971
 972                         if (!copied)
 973                                 TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
 974
 975                         tp->write_seq += copy;
 976                         TCP_SKB_CB(skb)->end_seq += copy;
 977                         skb_shinfo(skb)->gso_segs = 0;
 978
 979                         from += copy;
 980                         copied += copy;
 981                         if ((seglen -= copy) == 0 && iovlen == 0)
 982                                 goto out;
 983
 984                         if (skb->len < size_goal || (flags & MSG_OOB))
 985                                 continue;
 986
 987                         if (forced_push(tp)) {
 988                                 tcp_mark_push(tp, skb);
 989                                 __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
 990                         } else if (skb == tcp_send_head(sk))
 991                                 tcp_push_one(sk, mss_now);
 992                         continue;
 993
 994 wait_for_sndbuf:
 995                         set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 996 wait_for_memory:
 997                         if (copied)
 998                                 tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
 999
1000                         if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
1001                                 goto do_error;
1002
1003                         mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
1004                         size_goal = tp->xmit_size_goal;
1005                 }
1006         }
1007
1008 out:
1009         if (copied)
1010                 tcp_push(sk, flags, mss_now, tp->nonagle);
1011         TCP_CHECK_TIMER(sk);
1012         release_sock(sk);
1013         return copied;
1014
1015 do_fault:
1016         if (!skb->len) {
1017                 tcp_unlink_write_queue(skb, sk);
1018                 /* It is the one place in all of TCP, except connection
1019                  * reset, where we can be unlinking the send_head.
1020                  */
1021                 tcp_check_send_head(sk, skb);
1022                 sk_wmem_free_skb(sk, skb);
1023         }
1024
1025 do_error:
1026         if (copied)
1027                 goto out;
1028 out_err:
1029         err = sk_stream_error(sk, flags, err);
1030         TCP_CHECK_TIMER(sk);
1031         release_sock(sk);
1032         return err;
1033 }
1034
1035 /*
1036  *      Handle reading urgent data. BSD has very simple semantics for
1037  *      this, no blocking and very strange errors 8)
1038  */
1039
1040 static int tcp_recv_urg(struct sock *sk, long timeo,
1041                         struct msghdr *msg, int len, int flags,
1042                         int *addr_len)
1043 {
1044         struct tcp_sock *tp = tcp_sk(sk);
1045
1046         /* No URG data to read. */
1047         if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
1048             tp->urg_data == TCP_URG_READ)
1049                 return -EINVAL; /* Yes this is right ! */
1050
1051         if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
1052                 return -ENOTCONN;
1053
1054         if (tp->urg_data & TCP_URG_VALID) {
1055                 int err = 0;
1056                 char c = tp->urg_data;
1057
1058                 if (!(flags & MSG_PEEK))
1059                         tp->urg_data = TCP_URG_READ;
1060
1061                 /* Read urgent data. */
1062                 msg->msg_flags |= MSG_OOB;
1063
1064                 if (len > 0) {
1065                         if (!(flags & MSG_TRUNC))
1066                                 err = memcpy_toiovec(msg->msg_iov, &c, 1);
1067                         len = 1;
1068                 } else
1069                         msg->msg_flags |= MSG_TRUNC;
1070
1071                 return err ? -EFAULT : len;
1072         }
1073
1074         if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
1075                 return 0;
1076
1077         /* Fixed the recv(..., MSG_OOB) behaviour.  BSD docs and
1078          * the available implementations agree in this case:
1079          * this call should never block, independent of the
1080          * blocking state of the socket.
1081          * Mike <pall@rz.uni-karlsruhe.de>
1082          */
1083         return -EAGAIN;
1084 }
1085
1086 /* Clean up the receive buffer for full frames taken by the user,
1087  * then send an ACK if necessary.  COPIED is the number of bytes
1088  * tcp_recvmsg has given to the user so far, it speeds up the
1089  * calculation of whether or not we must ACK for the sake of
1090  * a window update.
1091  */
1092 void tcp_cleanup_rbuf(struct sock *sk, int copied)
1093 {
1094         struct tcp_sock *tp = tcp_sk(sk);
1095         int time_to_ack = 0;
1096
1097 #if TCP_DEBUG
1098         struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
1099
1100         BUG_TRAP(!skb || before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq));
1101 #endif
1102
1103         if (inet_csk_ack_scheduled(sk)) {
1104                 const struct inet_connection_sock *icsk = inet_csk(sk);
1105                    /* Delayed ACKs frequently hit locked sockets during bulk
1106                     * receive. */
1107                 if (icsk->icsk_ack.blocked ||
1108                     /* Once-per-two-segments ACK was not sent by tcp_input.c */
1109                     tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
1110                     /*
1111                      * If this read emptied read buffer, we send ACK, if
1112                      * connection is not bidirectional, user drained
1113                      * receive buffer and there was a small segment
1114                      * in queue.
1115                      */
1116                     (copied > 0 &&
1117                      ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) ||
1118                       ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
1119                        !icsk->icsk_ack.pingpong)) &&
1120                       !atomic_read(&sk->sk_rmem_alloc)))
1121                         time_to_ack = 1;
1122         }
1123
1124         /* We send an ACK if we can now advertise a non-zero window
1125          * which has been raised "significantly".
1126          *
1127          * Even if window raised up to infinity, do not send window open ACK
1128          * in states, where we will not receive more. It is useless.
1129          */
1130         if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
1131                 __u32 rcv_window_now = tcp_receive_window(tp);
1132
1133                 /* Optimize, __tcp_select_window() is not cheap. */
1134                 if (2*rcv_window_now <= tp->window_clamp) {
1135                         __u32 new_window = __tcp_select_window(sk);
1136
1137                         /* Send ACK now, if this read freed lots of space
1138                          * in our buffer. Certainly, new_window is new window.
1139                          * We can advertise it now, if it is not less than current one.
1140                          * "Lots" means "at least twice" here.
1141                          */
1142                         if (new_window && new_window >= 2 * rcv_window_now)
1143                                 time_to_ack = 1;
1144                 }
1145         }
1146         if (time_to_ack)
1147                 tcp_send_ack(sk);
1148 }
1149
1150 static void tcp_prequeue_process(struct sock *sk)
1151 {
1152         struct sk_buff *skb;
1153         struct tcp_sock *tp = tcp_sk(sk);
1154
1155         NET_INC_STATS_USER(LINUX_MIB_TCPPREQUEUED);
1156
1157         /* RX process wants to run with disabled BHs, though it is not
1158          * necessary */
1159         local_bh_disable();
1160         while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)
1161                 sk->sk_backlog_rcv(sk, skb);
1162         local_bh_enable();
1163
1164         /* Clear memory counter. */
1165         tp->ucopy.memory = 0;
1166 }
1167
1168 static inline struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
1169 {
1170         struct sk_buff *skb;
1171         u32 offset;
1172
1173         skb_queue_walk(&sk->sk_receive_queue, skb) {
1174                 offset = seq - TCP_SKB_CB(skb)->seq;
1175                 if (tcp_hdr(skb)->syn)
1176                         offset--;
1177                 if (offset < skb->len || tcp_hdr(skb)->fin) {
1178                         *off = offset;
1179                         return skb;
1180                 }
1181         }
1182         return NULL;
1183 }
1184
1185 /*
1186  * This routine provides an alternative to tcp_recvmsg() for routines
1187  * that would like to handle copying from skbuffs directly in 'sendfile'
1188  * fashion.
1189  * Note:
1190  *      - It is assumed that the socket was locked by the caller.
1191  *      - The routine does not block.
1192  *      - At present, there is no support for reading OOB data
1193  *        or for 'peeking' the socket using this routine
1194  *        (although both would be easy to implement).
1195  */
1196 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
1197                   sk_read_actor_t recv_actor)
1198 {
1199         struct sk_buff *skb;
1200         struct tcp_sock *tp = tcp_sk(sk);
1201         u32 seq = tp->copied_seq;
1202         u32 offset;
1203         int copied = 0;
1204
1205         if (sk->sk_state == TCP_LISTEN)
1206                 return -ENOTCONN;
1207         while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
1208                 if (offset < skb->len) {
1209                         size_t used, 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                         if (offset != skb->len)
1231                                 break;
1232                 }
1233                 if (tcp_hdr(skb)->fin) {
1234                         sk_eat_skb(sk, skb, 0);
1235                         ++seq;
1236                         break;
1237                 }
1238                 sk_eat_skb(sk, skb, 0);
1239                 if (!desc->count)
1240                         break;
1241         }
1242         tp->copied_seq = seq;
1243
1244         tcp_rcv_space_adjust(sk);
1245
1246         /* Clean up data we have read: This will do ACK frames. */
1247         if (copied > 0)
1248                 tcp_cleanup_rbuf(sk, copied);
1249         return copied;
1250 }
1251
1252 /*
1253  *      This routine copies from a sock struct into the user buffer.
1254  *
1255  *      Technical note: in 2.3 we work on _locked_ socket, so that
1256  *      tricks with *seq access order and skb->users are not required.
1257  *      Probably, code can be easily improved even more.
1258  */
1259
1260 int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
1261                 size_t len, int nonblock, int flags, int *addr_len)
1262 {
1263         struct tcp_sock *tp = tcp_sk(sk);
1264         int copied = 0;
1265         u32 peek_seq;
1266         u32 *seq;
1267         unsigned long used;
1268         int err;
1269         int target;             /* Read at least this many bytes */
1270         long timeo;
1271         struct task_struct *user_recv = NULL;
1272         int copied_early = 0;
1273         struct sk_buff *skb;
1274
1275         lock_sock(sk);
1276
1277         TCP_CHECK_TIMER(sk);
1278
1279         err = -ENOTCONN;
1280         if (sk->sk_state == TCP_LISTEN)
1281                 goto out;
1282
1283         timeo = sock_rcvtimeo(sk, nonblock);
1284
1285         /* Urgent data needs to be handled specially. */
1286         if (flags & MSG_OOB)
1287                 goto recv_urg;
1288
1289         seq = &tp->copied_seq;
1290         if (flags & MSG_PEEK) {
1291                 peek_seq = tp->copied_seq;
1292                 seq = &peek_seq;
1293         }
1294
1295         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
1296
1297 #ifdef CONFIG_NET_DMA
1298         tp->ucopy.dma_chan = NULL;
1299         preempt_disable();
1300         skb = skb_peek_tail(&sk->sk_receive_queue);
1301         {
1302                 int available = 0;
1303
1304                 if (skb)
1305                         available = TCP_SKB_CB(skb)->seq + skb->len - (*seq);
1306                 if ((available < target) &&
1307                     (len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) &&
1308                     !sysctl_tcp_low_latency &&
1309                     __get_cpu_var(softnet_data).net_dma) {
1310                         preempt_enable_no_resched();
1311                         tp->ucopy.pinned_list =
1312                                         dma_pin_iovec_pages(msg->msg_iov, len);
1313                 } else {
1314                         preempt_enable_no_resched();
1315                 }
1316         }
1317 #endif
1318
1319         do {
1320                 u32 offset;
1321
1322                 /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
1323                 if (tp->urg_data && tp->urg_seq == *seq) {
1324                         if (copied)
1325                                 break;
1326                         if (signal_pending(current)) {
1327                                 copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
1328                                 break;
1329                         }
1330                 }
1331
1332                 /* Next get a buffer. */
1333
1334                 skb = skb_peek(&sk->sk_receive_queue);
1335                 do {
1336                         if (!skb)
1337                                 break;
1338
1339                         /* Now that we have two receive queues this
1340                          * shouldn't happen.
1341                          */
1342                         if (before(*seq, TCP_SKB_CB(skb)->seq)) {
1343                                 printk(KERN_INFO "recvmsg bug: copied %X "
1344                                        "seq %X\n", *seq, TCP_SKB_CB(skb)->seq);
1345                                 break;
1346                         }
1347                         offset = *seq - TCP_SKB_CB(skb)->seq;
1348                         if (tcp_hdr(skb)->syn)
1349                                 offset--;
1350                         if (offset < skb->len)
1351                                 goto found_ok_skb;
1352                         if (tcp_hdr(skb)->fin)
1353                                 goto found_fin_ok;
1354                         BUG_TRAP(flags & MSG_PEEK);
1355                         skb = skb->next;
1356                 } while (skb != (struct sk_buff *)&sk->sk_receive_queue);
1357
1358                 /* Well, if we have backlog, try to process it now yet. */
1359
1360                 if (copied >= target && !sk->sk_backlog.tail)
1361                         break;
1362
1363                 if (copied) {
1364                         if (sk->sk_err ||
1365                             sk->sk_state == TCP_CLOSE ||
1366                             (sk->sk_shutdown & RCV_SHUTDOWN) ||
1367                             !timeo ||
1368                             signal_pending(current) ||
1369                             (flags & MSG_PEEK))
1370                                 break;
1371                 } else {
1372                         if (sock_flag(sk, SOCK_DONE))
1373                                 break;
1374
1375                         if (sk->sk_err) {
1376                                 copied = sock_error(sk);
1377                                 break;
1378                         }
1379
1380                         if (sk->sk_shutdown & RCV_SHUTDOWN)
1381                                 break;
1382
1383                         if (sk->sk_state == TCP_CLOSE) {
1384                                 if (!sock_flag(sk, SOCK_DONE)) {
1385                                         /* This occurs when user tries to read
1386                                          * from never connected socket.
1387                                          */
1388                                         copied = -ENOTCONN;
1389                                         break;
1390                                 }
1391                                 break;
1392                         }
1393
1394                         if (!timeo) {
1395                                 copied = -EAGAIN;
1396                                 break;
1397                         }
1398
1399                         if (signal_pending(current)) {
1400                                 copied = sock_intr_errno(timeo);
1401                                 break;
1402                         }
1403                 }
1404
1405                 tcp_cleanup_rbuf(sk, copied);
1406
1407                 if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) {
1408                         /* Install new reader */
1409                         if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) {
1410                                 user_recv = current;
1411                                 tp->ucopy.task = user_recv;
1412                                 tp->ucopy.iov = msg->msg_iov;
1413                         }
1414
1415                         tp->ucopy.len = len;
1416
1417                         BUG_TRAP(tp->copied_seq == tp->rcv_nxt ||
1418                                  (flags & (MSG_PEEK | MSG_TRUNC)));
1419
1420                         /* Ugly... If prequeue is not empty, we have to
1421                          * process it before releasing socket, otherwise
1422                          * order will be broken at second iteration.
1423                          * More elegant solution is required!!!
1424                          *
1425                          * Look: we have the following (pseudo)queues:
1426                          *
1427                          * 1. packets in flight
1428                          * 2. backlog
1429                          * 3. prequeue
1430                          * 4. receive_queue
1431                          *
1432                          * Each queue can be processed only if the next ones
1433                          * are empty. At this point we have empty receive_queue.
1434                          * But prequeue _can_ be not empty after 2nd iteration,
1435                          * when we jumped to start of loop because backlog
1436                          * processing added something to receive_queue.
1437                          * We cannot release_sock(), because backlog contains
1438                          * packets arrived _after_ prequeued ones.
1439                          *
1440                          * Shortly, algorithm is clear --- to process all
1441                          * the queues in order. We could make it more directly,
1442                          * requeueing packets from backlog to prequeue, if
1443                          * is not empty. It is more elegant, but eats cycles,
1444                          * unfortunately.
1445                          */
1446                         if (!skb_queue_empty(&tp->ucopy.prequeue))
1447                                 goto do_prequeue;
1448
1449                         /* __ Set realtime policy in scheduler __ */
1450                 }
1451
1452                 if (copied >= target) {
1453                         /* Do not sleep, just process backlog. */
1454                         release_sock(sk);
1455                         lock_sock(sk);
1456                 } else
1457                         sk_wait_data(sk, &timeo);
1458
1459 #ifdef CONFIG_NET_DMA
1460                 tp->ucopy.wakeup = 0;
1461 #endif
1462
1463                 if (user_recv) {
1464                         int chunk;
1465
1466                         /* __ Restore normal policy in scheduler __ */
1467
1468                         if ((chunk = len - tp->ucopy.len) != 0) {
1469                                 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk);
1470                                 len -= chunk;
1471                                 copied += chunk;
1472                         }
1473
1474                         if (tp->rcv_nxt == tp->copied_seq &&
1475                             !skb_queue_empty(&tp->ucopy.prequeue)) {
1476 do_prequeue:
1477                                 tcp_prequeue_process(sk);
1478
1479                                 if ((chunk = len - tp->ucopy.len) != 0) {
1480                                         NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1481                                         len -= chunk;
1482                                         copied += chunk;
1483                                 }
1484                         }
1485                 }
1486                 if ((flags & MSG_PEEK) && peek_seq != tp->copied_seq) {
1487                         if (net_ratelimit())
1488                                 printk(KERN_DEBUG "TCP(%s:%d): Application bug, race in MSG_PEEK.\n",
1489                                        current->comm, task_pid_nr(current));
1490                         peek_seq = tp->copied_seq;
1491                 }
1492                 continue;
1493
1494         found_ok_skb:
1495                 /* Ok so how much can we use? */
1496                 used = skb->len - offset;
1497                 if (len < used)
1498                         used = len;
1499
1500                 /* Do we have urgent data here? */
1501                 if (tp->urg_data) {
1502                         u32 urg_offset = tp->urg_seq - *seq;
1503                         if (urg_offset < used) {
1504                                 if (!urg_offset) {
1505                                         if (!sock_flag(sk, SOCK_URGINLINE)) {
1506                                                 ++*seq;
1507                                                 offset++;
1508                                                 used--;
1509                                                 if (!used)
1510                                                         goto skip_copy;
1511                                         }
1512                                 } else
1513                                         used = urg_offset;
1514                         }
1515                 }
1516
1517                 if (!(flags & MSG_TRUNC)) {
1518 #ifdef CONFIG_NET_DMA
1519                         if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1520                                 tp->ucopy.dma_chan = get_softnet_dma();
1521
1522                         if (tp->ucopy.dma_chan) {
1523                                 tp->ucopy.dma_cookie = dma_skb_copy_datagram_iovec(
1524                                         tp->ucopy.dma_chan, skb, offset,
1525                                         msg->msg_iov, used,
1526                                         tp->ucopy.pinned_list);
1527
1528                                 if (tp->ucopy.dma_cookie < 0) {
1529
1530                                         printk(KERN_ALERT "dma_cookie < 0\n");
1531
1532                                         /* Exception. Bailout! */
1533                                         if (!copied)
1534                                                 copied = -EFAULT;
1535                                         break;
1536                                 }
1537                                 if ((offset + used) == skb->len)
1538                                         copied_early = 1;
1539
1540                         } else
1541 #endif
1542                         {
1543                                 err = skb_copy_datagram_iovec(skb, offset,
1544                                                 msg->msg_iov, used);
1545                                 if (err) {
1546                                         /* Exception. Bailout! */
1547                                         if (!copied)
1548                                                 copied = -EFAULT;
1549                                         break;
1550                                 }
1551                         }
1552                 }
1553
1554                 *seq += used;
1555                 copied += used;
1556                 len -= used;
1557
1558                 tcp_rcv_space_adjust(sk);
1559
1560 skip_copy:
1561                 if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) {
1562                         tp->urg_data = 0;
1563                         tcp_fast_path_check(sk);
1564                 }
1565                 if (used + offset < skb->len)
1566                         continue;
1567
1568                 if (tcp_hdr(skb)->fin)
1569                         goto found_fin_ok;
1570                 if (!(flags & MSG_PEEK)) {
1571                         sk_eat_skb(sk, skb, copied_early);
1572                         copied_early = 0;
1573                 }
1574                 continue;
1575
1576         found_fin_ok:
1577                 /* Process the FIN. */
1578                 ++*seq;
1579                 if (!(flags & MSG_PEEK)) {
1580                         sk_eat_skb(sk, skb, copied_early);
1581                         copied_early = 0;
1582                 }
1583                 break;
1584         } while (len > 0);
1585
1586         if (user_recv) {
1587                 if (!skb_queue_empty(&tp->ucopy.prequeue)) {
1588                         int chunk;
1589
1590                         tp->ucopy.len = copied > 0 ? len : 0;
1591
1592                         tcp_prequeue_process(sk);
1593
1594                         if (copied > 0 && (chunk = len - tp->ucopy.len) != 0) {
1595                                 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1596                                 len -= chunk;
1597                                 copied += chunk;
1598                         }
1599                 }
1600
1601                 tp->ucopy.task = NULL;
1602                 tp->ucopy.len = 0;
1603         }
1604
1605 #ifdef CONFIG_NET_DMA
1606         if (tp->ucopy.dma_chan) {
1607                 dma_cookie_t done, used;
1608
1609                 dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
1610
1611                 while (dma_async_memcpy_complete(tp->ucopy.dma_chan,
1612                                                  tp->ucopy.dma_cookie, &done,
1613                                                  &used) == DMA_IN_PROGRESS) {
1614                         /* do partial cleanup of sk_async_wait_queue */
1615                         while ((skb = skb_peek(&sk->sk_async_wait_queue)) &&
1616                                (dma_async_is_complete(skb->dma_cookie, done,
1617                                                       used) == DMA_SUCCESS)) {
1618                                 __skb_dequeue(&sk->sk_async_wait_queue);
1619                                 kfree_skb(skb);
1620                         }
1621                 }
1622
1623                 /* Safe to free early-copied skbs now */
1624                 __skb_queue_purge(&sk->sk_async_wait_queue);
1625                 dma_chan_put(tp->ucopy.dma_chan);
1626                 tp->ucopy.dma_chan = NULL;
1627         }
1628         if (tp->ucopy.pinned_list) {
1629                 dma_unpin_iovec_pages(tp->ucopy.pinned_list);
1630                 tp->ucopy.pinned_list = NULL;
1631         }
1632 #endif
1633
1634         /* According to UNIX98, msg_name/msg_namelen are ignored
1635          * on connected socket. I was just happy when found this 8) --ANK
1636          */
1637
1638         /* Clean up data we have read: This will do ACK frames. */
1639         tcp_cleanup_rbuf(sk, copied);
1640
1641         TCP_CHECK_TIMER(sk);
1642         release_sock(sk);
1643         return copied;
1644
1645 out:
1646         TCP_CHECK_TIMER(sk);
1647         release_sock(sk);
1648         return err;
1649
1650 recv_urg:
1651         err = tcp_recv_urg(sk, timeo, msg, len, flags, addr_len);
1652         goto out;
1653 }
1654
1655 void tcp_set_state(struct sock *sk, int state)
1656 {
1657         int oldstate = sk->sk_state;
1658
1659         switch (state) {
1660         case TCP_ESTABLISHED:
1661                 if (oldstate != TCP_ESTABLISHED)
1662                         TCP_INC_STATS(TCP_MIB_CURRESTAB);
1663                 break;
1664
1665         case TCP_CLOSE:
1666                 if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
1667                         TCP_INC_STATS(TCP_MIB_ESTABRESETS);
1668
1669                 sk->sk_prot->unhash(sk);
1670                 if (inet_csk(sk)->icsk_bind_hash &&
1671                     !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
1672                         inet_put_port(sk);
1673                 /* fall through */
1674         default:
1675                 if (oldstate==TCP_ESTABLISHED)
1676                         TCP_DEC_STATS(TCP_MIB_CURRESTAB);
1677         }
1678
1679         /* Change state AFTER socket is unhashed to avoid closed
1680          * socket sitting in hash tables.
1681          */
1682         sk->sk_state = state;
1683
1684 #ifdef STATE_TRACE
1685         SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n",sk, statename[oldstate],statename[state]);
1686 #endif
1687 }
1688 EXPORT_SYMBOL_GPL(tcp_set_state);
1689
1690 /*
1691  *      State processing on a close. This implements the state shift for
1692  *      sending our FIN frame. Note that we only send a FIN for some
1693  *      states. A shutdown() may have already sent the FIN, or we may be
1694  *      closed.
1695  */
1696
1697 static const unsigned char new_state[16] = {
1698   /* current state:        new state:      action:      */
1699   /* (Invalid)          */ TCP_CLOSE,
1700   /* TCP_ESTABLISHED    */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1701   /* TCP_SYN_SENT       */ TCP_CLOSE,
1702   /* TCP_SYN_RECV       */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1703   /* TCP_FIN_WAIT1      */ TCP_FIN_WAIT1,
1704   /* TCP_FIN_WAIT2      */ TCP_FIN_WAIT2,
1705   /* TCP_TIME_WAIT      */ TCP_CLOSE,
1706   /* TCP_CLOSE          */ TCP_CLOSE,
1707   /* TCP_CLOSE_WAIT     */ TCP_LAST_ACK  | TCP_ACTION_FIN,
1708   /* TCP_LAST_ACK       */ TCP_LAST_ACK,
1709   /* TCP_LISTEN         */ TCP_CLOSE,
1710   /* TCP_CLOSING        */ TCP_CLOSING,
1711 };
1712
1713 static int tcp_close_state(struct sock *sk)
1714 {
1715         int next = (int)new_state[sk->sk_state];
1716         int ns = next & TCP_STATE_MASK;
1717
1718         tcp_set_state(sk, ns);
1719
1720         return next & TCP_ACTION_FIN;
1721 }
1722
1723 /*
1724  *      Shutdown the sending side of a connection. Much like close except
1725  *      that we don't receive shut down or sock_set_flag(sk, SOCK_DEAD).
1726  */
1727
1728 void tcp_shutdown(struct sock *sk, int how)
1729 {
1730         /*      We need to grab some memory, and put together a FIN,
1731          *      and then put it into the queue to be sent.
1732          *              Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
1733          */
1734         if (!(how & SEND_SHUTDOWN))
1735                 return;
1736
1737         /* If we've already sent a FIN, or it's a closed state, skip this. */
1738         if ((1 << sk->sk_state) &
1739             (TCPF_ESTABLISHED | TCPF_SYN_SENT |
1740              TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
1741                 /* Clear out any half completed packets.  FIN if needed. */
1742                 if (tcp_close_state(sk))
1743                         tcp_send_fin(sk);
1744         }
1745 }
1746
1747 void tcp_close(struct sock *sk, long timeout)
1748 {
1749         struct sk_buff *skb;
1750         int data_was_unread = 0;
1751         int state;
1752
1753         lock_sock(sk);
1754         sk->sk_shutdown = SHUTDOWN_MASK;
1755
1756         if (sk->sk_state == TCP_LISTEN) {
1757                 tcp_set_state(sk, TCP_CLOSE);
1758
1759                 /* Special case. */
1760                 inet_csk_listen_stop(sk);
1761
1762                 goto adjudge_to_death;
1763         }
1764
1765         /*  We need to flush the recv. buffs.  We do this only on the
1766          *  descriptor close, not protocol-sourced closes, because the
1767          *  reader process may not have drained the data yet!
1768          */
1769         while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
1770                 u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq -
1771                           tcp_hdr(skb)->fin;
1772                 data_was_unread += len;
1773                 __kfree_skb(skb);
1774         }
1775
1776         sk_mem_reclaim(sk);
1777
1778         /* As outlined in RFC 2525, section 2.17, we send a RST here because
1779          * data was lost. To witness the awful effects of the old behavior of
1780          * always doing a FIN, run an older 2.1.x kernel or 2.0.x, start a bulk
1781          * GET in an FTP client, suspend the process, wait for the client to
1782          * advertise a zero window, then kill -9 the FTP client, wheee...
1783          * Note: timeout is always zero in such a case.
1784          */
1785         if (data_was_unread) {
1786                 /* Unread data was tossed, zap the connection. */
1787                 NET_INC_STATS_USER(LINUX_MIB_TCPABORTONCLOSE);
1788                 tcp_set_state(sk, TCP_CLOSE);
1789                 tcp_send_active_reset(sk, GFP_KERNEL);
1790         } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
1791                 /* Check zero linger _after_ checking for unread data. */
1792                 sk->sk_prot->disconnect(sk, 0);
1793                 NET_INC_STATS_USER(LINUX_MIB_TCPABORTONDATA);
1794         } else if (tcp_close_state(sk)) {
1795                 /* We FIN if the application ate all the data before
1796                  * zapping the connection.
1797                  */
1798
1799                 /* RED-PEN. Formally speaking, we have broken TCP state
1800                  * machine. State transitions:
1801                  *
1802                  * TCP_ESTABLISHED -> TCP_FIN_WAIT1
1803                  * TCP_SYN_RECV -> TCP_FIN_WAIT1 (forget it, it's impossible)
1804                  * TCP_CLOSE_WAIT -> TCP_LAST_ACK
1805                  *
1806                  * are legal only when FIN has been sent (i.e. in window),
1807                  * rather than queued out of window. Purists blame.
1808                  *
1809                  * F.e. "RFC state" is ESTABLISHED,
1810                  * if Linux state is FIN-WAIT-1, but FIN is still not sent.
1811                  *
1812                  * The visible declinations are that sometimes
1813                  * we enter time-wait state, when it is not required really
1814                  * (harmless), do not send active resets, when they are
1815                  * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when
1816                  * they look as CLOSING or LAST_ACK for Linux)
1817                  * Probably, I missed some more holelets.
1818                  *                                              --ANK
1819                  */
1820                 tcp_send_fin(sk);
1821         }
1822
1823         sk_stream_wait_close(sk, timeout);
1824
1825 adjudge_to_death:
1826         state = sk->sk_state;
1827         sock_hold(sk);
1828         sock_orphan(sk);
1829         atomic_inc(sk->sk_prot->orphan_count);
1830
1831         /* It is the last release_sock in its life. It will remove backlog. */
1832         release_sock(sk);
1833
1834
1835         /* Now socket is owned by kernel and we acquire BH lock
1836            to finish close. No need to check for user refs.
1837          */
1838         local_bh_disable();
1839         bh_lock_sock(sk);
1840         BUG_TRAP(!sock_owned_by_user(sk));
1841
1842         /* Have we already been destroyed by a softirq or backlog? */
1843         if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
1844                 goto out;
1845
1846         /*      This is a (useful) BSD violating of the RFC. There is a
1847          *      problem with TCP as specified in that the other end could
1848          *      keep a socket open forever with no application left this end.
1849          *      We use a 3 minute timeout (about the same as BSD) then kill
1850          *      our end. If they send after that then tough - BUT: long enough
1851          *      that we won't make the old 4*rto = almost no time - whoops
1852          *      reset mistake.
1853          *
1854          *      Nope, it was not mistake. It is really desired behaviour
1855          *      f.e. on http servers, when such sockets are useless, but
1856          *      consume significant resources. Let's do it with special
1857          *      linger2 option.                                 --ANK
1858          */
1859
1860         if (sk->sk_state == TCP_FIN_WAIT2) {
1861                 struct tcp_sock *tp = tcp_sk(sk);
1862                 if (tp->linger2 < 0) {
1863                         tcp_set_state(sk, TCP_CLOSE);
1864                         tcp_send_active_reset(sk, GFP_ATOMIC);
1865                         NET_INC_STATS_BH(LINUX_MIB_TCPABORTONLINGER);
1866                 } else {
1867                         const int tmo = tcp_fin_time(sk);
1868
1869                         if (tmo > TCP_TIMEWAIT_LEN) {
1870                                 inet_csk_reset_keepalive_timer(sk,
1871                                                 tmo - TCP_TIMEWAIT_LEN);
1872                         } else {
1873                                 tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
1874                                 goto out;
1875                         }
1876                 }
1877         }
1878         if (sk->sk_state != TCP_CLOSE) {
1879                 sk_mem_reclaim(sk);
1880                 if (tcp_too_many_orphans(sk,
1881                                 atomic_read(sk->sk_prot->orphan_count))) {
1882                         if (net_ratelimit())
1883                                 printk(KERN_INFO "TCP: too many of orphaned "
1884                                        "sockets\n");
1885                         tcp_set_state(sk, TCP_CLOSE);
1886                         tcp_send_active_reset(sk, GFP_ATOMIC);
1887                         NET_INC_STATS_BH(LINUX_MIB_TCPABORTONMEMORY);
1888                 }
1889         }
1890
1891         if (sk->sk_state == TCP_CLOSE)
1892                 inet_csk_destroy_sock(sk);
1893         /* Otherwise, socket is reprieved until protocol close. */
1894
1895 out:
1896         bh_unlock_sock(sk);
1897         local_bh_enable();
1898         sock_put(sk);
1899 }
1900
1901 /* These states need RST on ABORT according to RFC793 */
1902
1903 static inline int tcp_need_reset(int state)
1904 {
1905         return (1 << state) &
1906                (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
1907                 TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
1908 }
1909
1910 int tcp_disconnect(struct sock *sk, int flags)
1911 {
1912         struct inet_sock *inet = inet_sk(sk);
1913         struct inet_connection_sock *icsk = inet_csk(sk);
1914         struct tcp_sock *tp = tcp_sk(sk);
1915         int err = 0;
1916         int old_state = sk->sk_state;
1917
1918         if (old_state != TCP_CLOSE)
1919                 tcp_set_state(sk, TCP_CLOSE);
1920
1921         /* ABORT function of RFC793 */
1922         if (old_state == TCP_LISTEN) {
1923                 inet_csk_listen_stop(sk);
1924         } else if (tcp_need_reset(old_state) ||
1925                    (tp->snd_nxt != tp->write_seq &&
1926                     (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
1927                 /* The last check adjusts for discrepancy of Linux wrt. RFC
1928                  * states
1929                  */
1930                 tcp_send_active_reset(sk, gfp_any());
1931                 sk->sk_err = ECONNRESET;
1932         } else if (old_state == TCP_SYN_SENT)
1933                 sk->sk_err = ECONNRESET;
1934
1935         tcp_clear_xmit_timers(sk);
1936         __skb_queue_purge(&sk->sk_receive_queue);
1937         tcp_write_queue_purge(sk);
1938         __skb_queue_purge(&tp->out_of_order_queue);
1939 #ifdef CONFIG_NET_DMA
1940         __skb_queue_purge(&sk->sk_async_wait_queue);
1941 #endif
1942
1943         inet->dport = 0;
1944
1945         if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
1946                 inet_reset_saddr(sk);
1947
1948         sk->sk_shutdown = 0;
1949         sock_reset_flag(sk, SOCK_DONE);
1950         tp->srtt = 0;
1951         if ((tp->write_seq += tp->max_window + 2) == 0)
1952                 tp->write_seq = 1;
1953         icsk->icsk_backoff = 0;
1954         tp->snd_cwnd = 2;
1955         icsk->icsk_probes_out = 0;
1956         tp->packets_out = 0;
1957         tp->snd_ssthresh = 0x7fffffff;
1958         tp->snd_cwnd_cnt = 0;
1959         tp->bytes_acked = 0;
1960         tcp_set_ca_state(sk, TCP_CA_Open);
1961         tcp_clear_retrans(tp);
1962         inet_csk_delack_init(sk);
1963         tcp_init_send_head(sk);
1964         memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
1965         __sk_dst_reset(sk);
1966
1967         BUG_TRAP(!inet->num || icsk->icsk_bind_hash);
1968
1969         sk->sk_error_report(sk);
1970         return err;
1971 }
1972
1973 /*
1974  *      Socket option code for TCP.
1975  */
1976 static int do_tcp_setsockopt(struct sock *sk, int level,
1977                 int optname, char __user *optval, int optlen)
1978 {
1979         struct tcp_sock *tp = tcp_sk(sk);
1980         struct inet_connection_sock *icsk = inet_csk(sk);
1981         int val;
1982         int err = 0;
1983
1984         /* This is a string value all the others are int's */
1985         if (optname == TCP_CONGESTION) {
1986                 char name[TCP_CA_NAME_MAX];
1987
1988                 if (optlen < 1)
1989                         return -EINVAL;
1990
1991                 val = strncpy_from_user(name, optval,
1992                                         min(TCP_CA_NAME_MAX-1, optlen));
1993                 if (val < 0)
1994                         return -EFAULT;
1995                 name[val] = 0;
1996
1997                 lock_sock(sk);
1998                 err = tcp_set_congestion_control(sk, name);
1999                 release_sock(sk);
2000                 return err;
2001         }
2002
2003         if (optlen < sizeof(int))
2004                 return -EINVAL;
2005
2006         if (get_user(val, (int __user *)optval))
2007                 return -EFAULT;
2008
2009         lock_sock(sk);
2010
2011         switch (optname) {
2012         case TCP_MAXSEG:
2013                 /* Values greater than interface MTU won't take effect. However
2014                  * at the point when this call is done we typically don't yet
2015                  * know which interface is going to be used */
2016                 if (val < 8 || val > MAX_TCP_WINDOW) {
2017                         err = -EINVAL;
2018                         break;
2019                 }
2020                 tp->rx_opt.user_mss = val;
2021                 break;
2022
2023         case TCP_NODELAY:
2024                 if (val) {
2025                         /* TCP_NODELAY is weaker than TCP_CORK, so that
2026                          * this option on corked socket is remembered, but
2027                          * it is not activated until cork is cleared.
2028                          *
2029                          * However, when TCP_NODELAY is set we make
2030                          * an explicit push, which overrides even TCP_CORK
2031                          * for currently queued segments.
2032                          */
2033                         tp->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
2034                         tcp_push_pending_frames(sk);
2035                 } else {
2036                         tp->nonagle &= ~TCP_NAGLE_OFF;
2037                 }
2038                 break;
2039
2040         case TCP_CORK:
2041                 /* When set indicates to always queue non-full frames.
2042                  * Later the user clears this option and we transmit
2043                  * any pending partial frames in the queue.  This is
2044                  * meant to be used alongside sendfile() to get properly
2045                  * filled frames when the user (for example) must write
2046                  * out headers with a write() call first and then use
2047                  * sendfile to send out the data parts.
2048                  *
2049                  * TCP_CORK can be set together with TCP_NODELAY and it is
2050                  * stronger than TCP_NODELAY.
2051                  */
2052                 if (val) {
2053                         tp->nonagle |= TCP_NAGLE_CORK;
2054                 } else {
2055                         tp->nonagle &= ~TCP_NAGLE_CORK;
2056                         if (tp->nonagle&TCP_NAGLE_OFF)
2057                                 tp->nonagle |= TCP_NAGLE_PUSH;
2058                         tcp_push_pending_frames(sk);
2059                 }
2060                 break;
2061
2062         case TCP_KEEPIDLE:
2063                 if (val < 1 || val > MAX_TCP_KEEPIDLE)
2064                         err = -EINVAL;
2065                 else {
2066                         tp->keepalive_time = val * HZ;
2067                         if (sock_flag(sk, SOCK_KEEPOPEN) &&
2068                             !((1 << sk->sk_state) &
2069                               (TCPF_CLOSE | TCPF_LISTEN))) {
2070                                 __u32 elapsed = tcp_time_stamp - tp->rcv_tstamp;
2071                                 if (tp->keepalive_time > elapsed)
2072                                         elapsed = tp->keepalive_time - elapsed;
2073                                 else
2074                                         elapsed = 0;
2075                                 inet_csk_reset_keepalive_timer(sk, elapsed);
2076                         }
2077                 }
2078                 break;
2079         case TCP_KEEPINTVL:
2080                 if (val < 1 || val > MAX_TCP_KEEPINTVL)
2081                         err = -EINVAL;
2082                 else
2083                         tp->keepalive_intvl = val * HZ;
2084                 break;
2085         case TCP_KEEPCNT:
2086                 if (val < 1 || val > MAX_TCP_KEEPCNT)
2087                         err = -EINVAL;
2088                 else
2089                         tp->keepalive_probes = val;
2090                 break;
2091         case TCP_SYNCNT:
2092                 if (val < 1 || val > MAX_TCP_SYNCNT)
2093                         err = -EINVAL;
2094                 else
2095                         icsk->icsk_syn_retries = val;
2096                 break;
2097
2098         case TCP_LINGER2:
2099                 if (val < 0)
2100                         tp->linger2 = -1;
2101                 else if (val > sysctl_tcp_fin_timeout / HZ)
2102                         tp->linger2 = 0;
2103                 else
2104                         tp->linger2 = val * HZ;
2105                 break;
2106
2107         case TCP_DEFER_ACCEPT:
2108                 if (val < 0) {
2109                         err = -EINVAL;
2110                 } else {
2111                         if (val > MAX_TCP_ACCEPT_DEFERRED)
2112                                 val = MAX_TCP_ACCEPT_DEFERRED;
2113                         icsk->icsk_accept_queue.rskq_defer_accept = val;
2114                 }
2115                 break;
2116
2117         case TCP_WINDOW_CLAMP:
2118                 if (!val) {
2119                         if (sk->sk_state != TCP_CLOSE) {
2120                                 err = -EINVAL;
2121                                 break;
2122                         }
2123                         tp->window_clamp = 0;
2124                 } else
2125                         tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
2126                                                 SOCK_MIN_RCVBUF / 2 : val;
2127                 break;
2128
2129         case TCP_QUICKACK:
2130                 if (!val) {
2131                         icsk->icsk_ack.pingpong = 1;
2132                 } else {
2133                         icsk->icsk_ack.pingpong = 0;
2134                         if ((1 << sk->sk_state) &
2135                             (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
2136                             inet_csk_ack_scheduled(sk)) {
2137                                 icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
2138                                 tcp_cleanup_rbuf(sk, 1);
2139                                 if (!(val & 1))
2140                                         icsk->icsk_ack.pingpong = 1;
2141                         }
2142                 }
2143                 break;
2144
2145 #ifdef CONFIG_TCP_MD5SIG
2146         case TCP_MD5SIG:
2147                 /* Read the IP->Key mappings from userspace */
2148                 err = tp->af_specific->md5_parse(sk, optval, optlen);
2149                 break;
2150 #endif
2151
2152         default:
2153                 err = -ENOPROTOOPT;
2154                 break;
2155         }
2156
2157         release_sock(sk);
2158         return err;
2159 }
2160
2161 int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
2162                    int optlen)
2163 {
2164         struct inet_connection_sock *icsk = inet_csk(sk);
2165
2166         if (level != SOL_TCP)
2167                 return icsk->icsk_af_ops->setsockopt(sk, level, optname,
2168                                                      optval, optlen);
2169         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2170 }
2171
2172 #ifdef CONFIG_COMPAT
2173 int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
2174                           char __user *optval, int optlen)
2175 {
2176         if (level != SOL_TCP)
2177                 return inet_csk_compat_setsockopt(sk, level, optname,
2178                                                   optval, optlen);
2179         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2180 }
2181
2182 EXPORT_SYMBOL(compat_tcp_setsockopt);
2183 #endif
2184
2185 /* Return information about state of tcp endpoint in API format. */
2186 void tcp_get_info(struct sock *sk, struct tcp_info *info)
2187 {
2188         struct tcp_sock *tp = tcp_sk(sk);
2189         const struct inet_connection_sock *icsk = inet_csk(sk);
2190         u32 now = tcp_time_stamp;
2191
2192         memset(info, 0, sizeof(*info));
2193
2194         info->tcpi_state = sk->sk_state;
2195         info->tcpi_ca_state = icsk->icsk_ca_state;
2196         info->tcpi_retransmits = icsk->icsk_retransmits;
2197         info->tcpi_probes = icsk->icsk_probes_out;
2198         info->tcpi_backoff = icsk->icsk_backoff;
2199
2200         if (tp->rx_opt.tstamp_ok)
2201                 info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
2202         if (tcp_is_sack(tp))
2203                 info->tcpi_options |= TCPI_OPT_SACK;
2204         if (tp->rx_opt.wscale_ok) {
2205                 info->tcpi_options |= TCPI_OPT_WSCALE;
2206                 info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
2207                 info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
2208         }
2209
2210         if (tp->ecn_flags&TCP_ECN_OK)
2211                 info->tcpi_options |= TCPI_OPT_ECN;
2212
2213         info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
2214         info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
2215         info->tcpi_snd_mss = tp->mss_cache;
2216         info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
2217
2218         if (sk->sk_state == TCP_LISTEN) {
2219                 info->tcpi_unacked = sk->sk_ack_backlog;
2220                 info->tcpi_sacked = sk->sk_max_ack_backlog;
2221         } else {
2222                 info->tcpi_unacked = tp->packets_out;
2223                 info->tcpi_sacked = tp->sacked_out;
2224         }
2225         info->tcpi_lost = tp->lost_out;
2226         info->tcpi_retrans = tp->retrans_out;
2227         info->tcpi_fackets = tp->fackets_out;
2228
2229         info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
2230         info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
2231         info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
2232
2233         info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
2234         info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
2235         info->tcpi_rtt = jiffies_to_usecs(tp->srtt)>>3;
2236         info->tcpi_rttvar = jiffies_to_usecs(tp->mdev)>>2;
2237         info->tcpi_snd_ssthresh = tp->snd_ssthresh;
2238         info->tcpi_snd_cwnd = tp->snd_cwnd;
2239         info->tcpi_advmss = tp->advmss;
2240         info->tcpi_reordering = tp->reordering;
2241
2242         info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3;
2243         info->tcpi_rcv_space = tp->rcvq_space.space;
2244
2245         info->tcpi_total_retrans = tp->total_retrans;
2246 }
2247
2248 EXPORT_SYMBOL_GPL(tcp_get_info);
2249
2250 static int do_tcp_getsockopt(struct sock *sk, int level,
2251                 int optname, char __user *optval, int __user *optlen)
2252 {
2253         struct inet_connection_sock *icsk = inet_csk(sk);
2254         struct tcp_sock *tp = tcp_sk(sk);
2255         int val, len;
2256
2257         if (get_user(len, optlen))
2258                 return -EFAULT;
2259
2260         len = min_t(unsigned int, len, sizeof(int));
2261
2262         if (len < 0)
2263                 return -EINVAL;
2264
2265         switch (optname) {
2266         case TCP_MAXSEG:
2267                 val = tp->mss_cache;
2268                 if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
2269                         val = tp->rx_opt.user_mss;
2270                 break;
2271         case TCP_NODELAY:
2272                 val = !!(tp->nonagle&TCP_NAGLE_OFF);
2273                 break;
2274         case TCP_CORK:
2275                 val = !!(tp->nonagle&TCP_NAGLE_CORK);
2276                 break;
2277         case TCP_KEEPIDLE:
2278                 val = (tp->keepalive_time ? : sysctl_tcp_keepalive_time) / HZ;
2279                 break;
2280         case TCP_KEEPINTVL:
2281                 val = (tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl) / HZ;
2282                 break;
2283         case TCP_KEEPCNT:
2284                 val = tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
2285                 break;
2286         case TCP_SYNCNT:
2287                 val = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
2288                 break;
2289         case TCP_LINGER2:
2290                 val = tp->linger2;
2291                 if (val >= 0)
2292                         val = (val ? : sysctl_tcp_fin_timeout) / HZ;
2293                 break;
2294         case TCP_DEFER_ACCEPT:
2295                 val = icsk->icsk_accept_queue.rskq_defer_accept;
2296                 break;
2297         case TCP_WINDOW_CLAMP:
2298                 val = tp->window_clamp;
2299                 break;
2300         case TCP_INFO: {
2301                 struct tcp_info info;
2302
2303                 if (get_user(len, optlen))
2304                         return -EFAULT;
2305
2306                 tcp_get_info(sk, &info);
2307
2308                 len = min_t(unsigned int, len, sizeof(info));
2309                 if (put_user(len, optlen))
2310                         return -EFAULT;
2311                 if (copy_to_user(optval, &info, len))
2312                         return -EFAULT;
2313                 return 0;
2314         }
2315         case TCP_QUICKACK:
2316                 val = !icsk->icsk_ack.pingpong;
2317                 break;
2318
2319         case TCP_CONGESTION:
2320                 if (get_user(len, optlen))
2321                         return -EFAULT;
2322                 len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
2323                 if (put_user(len, optlen))
2324                         return -EFAULT;
2325                 if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
2326                         return -EFAULT;
2327                 return 0;
2328         default:
2329                 return -ENOPROTOOPT;
2330         }
2331
2332         if (put_user(len, optlen))
2333                 return -EFAULT;
2334         if (copy_to_user(optval, &val, len))
2335                 return -EFAULT;
2336         return 0;
2337 }
2338
2339 int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
2340                    int __user *optlen)
2341 {
2342         struct inet_connection_sock *icsk = inet_csk(sk);
2343
2344         if (level != SOL_TCP)
2345                 return icsk->icsk_af_ops->getsockopt(sk, level, optname,
2346                                                      optval, optlen);
2347         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2348 }
2349
2350 #ifdef CONFIG_COMPAT
2351 int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
2352                           char __user *optval, int __user *optlen)
2353 {
2354         if (level != SOL_TCP)
2355                 return inet_csk_compat_getsockopt(sk, level, optname,
2356                                                   optval, optlen);
2357         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2358 }
2359
2360 EXPORT_SYMBOL(compat_tcp_getsockopt);
2361 #endif
2362
2363 struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int features)
2364 {
2365         struct sk_buff *segs = ERR_PTR(-EINVAL);
2366         struct tcphdr *th;
2367         unsigned thlen;
2368         unsigned int seq;
2369         __be32 delta;
2370         unsigned int oldlen;
2371         unsigned int len;
2372
2373         if (!pskb_may_pull(skb, sizeof(*th)))
2374                 goto out;
2375
2376         th = tcp_hdr(skb);
2377         thlen = th->doff * 4;
2378         if (thlen < sizeof(*th))
2379                 goto out;
2380
2381         if (!pskb_may_pull(skb, thlen))
2382                 goto out;
2383
2384         oldlen = (u16)~skb->len;
2385         __skb_pull(skb, thlen);
2386
2387         if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
2388                 /* Packet is from an untrusted source, reset gso_segs. */
2389                 int type = skb_shinfo(skb)->gso_type;
2390                 int mss;
2391
2392                 if (unlikely(type &
2393                              ~(SKB_GSO_TCPV4 |
2394                                SKB_GSO_DODGY |
2395                                SKB_GSO_TCP_ECN |
2396                                SKB_GSO_TCPV6 |
2397                                0) ||
2398                              !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))))
2399                         goto out;
2400
2401                 mss = skb_shinfo(skb)->gso_size;
2402                 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
2403
2404                 segs = NULL;
2405                 goto out;
2406         }
2407
2408         segs = skb_segment(skb, features);
2409         if (IS_ERR(segs))
2410                 goto out;
2411
2412         len = skb_shinfo(skb)->gso_size;
2413         delta = htonl(oldlen + (thlen + len));
2414
2415         skb = segs;
2416         th = tcp_hdr(skb);
2417         seq = ntohl(th->seq);
2418
2419         do {
2420                 th->fin = th->psh = 0;
2421
2422                 th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
2423                                        (__force u32)delta));
2424                 if (skb->ip_summed != CHECKSUM_PARTIAL)
2425                         th->check =
2426                              csum_fold(csum_partial(skb_transport_header(skb),
2427                                                     thlen, skb->csum));
2428
2429                 seq += len;
2430                 skb = skb->next;
2431                 th = tcp_hdr(skb);
2432
2433                 th->seq = htonl(seq);
2434                 th->cwr = 0;
2435         } while (skb->next);
2436
2437         delta = htonl(oldlen + (skb->tail - skb->transport_header) +
2438                       skb->data_len);
2439         th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
2440                                 (__force u32)delta));
2441         if (skb->ip_summed != CHECKSUM_PARTIAL)
2442                 th->check = csum_fold(csum_partial(skb_transport_header(skb),
2443                                                    thlen, skb->csum));
2444
2445 out:
2446         return segs;
2447 }
2448 EXPORT_SYMBOL(tcp_tso_segment);
2449
2450 #ifdef CONFIG_TCP_MD5SIG
2451 static unsigned long tcp_md5sig_users;
2452 static struct tcp_md5sig_pool **tcp_md5sig_pool;
2453 static DEFINE_SPINLOCK(tcp_md5sig_pool_lock);
2454
2455 static void __tcp_free_md5sig_pool(struct tcp_md5sig_pool **pool)
2456 {
2457         int cpu;
2458         for_each_possible_cpu(cpu) {
2459                 struct tcp_md5sig_pool *p = *per_cpu_ptr(pool, cpu);
2460                 if (p) {
2461                         if (p->md5_desc.tfm)
2462                                 crypto_free_hash(p->md5_desc.tfm);
2463                         kfree(p);
2464                         p = NULL;
2465                 }
2466         }
2467         free_percpu(pool);
2468 }
2469
2470 void tcp_free_md5sig_pool(void)
2471 {
2472         struct tcp_md5sig_pool **pool = NULL;
2473
2474         spin_lock_bh(&tcp_md5sig_pool_lock);
2475         if (--tcp_md5sig_users == 0) {
2476                 pool = tcp_md5sig_pool;
2477                 tcp_md5sig_pool = NULL;
2478         }
2479         spin_unlock_bh(&tcp_md5sig_pool_lock);
2480         if (pool)
2481                 __tcp_free_md5sig_pool(pool);
2482 }
2483
2484 EXPORT_SYMBOL(tcp_free_md5sig_pool);
2485
2486 static struct tcp_md5sig_pool **__tcp_alloc_md5sig_pool(void)
2487 {
2488         int cpu;
2489         struct tcp_md5sig_pool **pool;
2490
2491         pool = alloc_percpu(struct tcp_md5sig_pool *);
2492         if (!pool)
2493                 return NULL;
2494
2495         for_each_possible_cpu(cpu) {
2496                 struct tcp_md5sig_pool *p;
2497                 struct crypto_hash *hash;
2498
2499                 p = kzalloc(sizeof(*p), GFP_KERNEL);
2500                 if (!p)
2501                         goto out_free;
2502                 *per_cpu_ptr(pool, cpu) = p;
2503
2504                 hash = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
2505                 if (!hash || IS_ERR(hash))
2506                         goto out_free;
2507
2508                 p->md5_desc.tfm = hash;
2509         }
2510         return pool;
2511 out_free:
2512         __tcp_free_md5sig_pool(pool);
2513         return NULL;
2514 }
2515
2516 struct tcp_md5sig_pool **tcp_alloc_md5sig_pool(void)
2517 {
2518         struct tcp_md5sig_pool **pool;
2519         int alloc = 0;
2520
2521 retry:
2522         spin_lock_bh(&tcp_md5sig_pool_lock);
2523         pool = tcp_md5sig_pool;
2524         if (tcp_md5sig_users++ == 0) {
2525                 alloc = 1;
2526                 spin_unlock_bh(&tcp_md5sig_pool_lock);
2527         } else if (!pool) {
2528                 tcp_md5sig_users--;
2529                 spin_unlock_bh(&tcp_md5sig_pool_lock);
2530                 cpu_relax();
2531                 goto retry;
2532         } else
2533                 spin_unlock_bh(&tcp_md5sig_pool_lock);
2534
2535         if (alloc) {
2536                 /* we cannot hold spinlock here because this may sleep. */
2537                 struct tcp_md5sig_pool **p = __tcp_alloc_md5sig_pool();
2538                 spin_lock_bh(&tcp_md5sig_pool_lock);
2539                 if (!p) {
2540                         tcp_md5sig_users--;
2541                         spin_unlock_bh(&tcp_md5sig_pool_lock);
2542                         return NULL;
2543                 }
2544                 pool = tcp_md5sig_pool;
2545                 if (pool) {
2546                         /* oops, it has already been assigned. */
2547                         spin_unlock_bh(&tcp_md5sig_pool_lock);
2548                         __tcp_free_md5sig_pool(p);
2549                 } else {
2550                         tcp_md5sig_pool = pool = p;
2551                         spin_unlock_bh(&tcp_md5sig_pool_lock);
2552                 }
2553         }
2554         return pool;
2555 }
2556
2557 EXPORT_SYMBOL(tcp_alloc_md5sig_pool);
2558
2559 struct tcp_md5sig_pool *__tcp_get_md5sig_pool(int cpu)
2560 {
2561         struct tcp_md5sig_pool **p;
2562         spin_lock_bh(&tcp_md5sig_pool_lock);
2563         p = tcp_md5sig_pool;
2564         if (p)
2565                 tcp_md5sig_users++;
2566         spin_unlock_bh(&tcp_md5sig_pool_lock);
2567         return (p ? *per_cpu_ptr(p, cpu) : NULL);
2568 }
2569
2570 EXPORT_SYMBOL(__tcp_get_md5sig_pool);
2571
2572 void __tcp_put_md5sig_pool(void)
2573 {
2574         tcp_free_md5sig_pool();
2575 }
2576
2577 EXPORT_SYMBOL(__tcp_put_md5sig_pool);
2578 #endif
2579
2580 void tcp_done(struct sock *sk)
2581 {
2582         if(sk->sk_state == TCP_SYN_SENT || sk->sk_state == TCP_SYN_RECV)
2583                 TCP_INC_STATS_BH(TCP_MIB_ATTEMPTFAILS);
2584
2585         tcp_set_state(sk, TCP_CLOSE);
2586         tcp_clear_xmit_timers(sk);
2587
2588         sk->sk_shutdown = SHUTDOWN_MASK;
2589
2590         if (!sock_flag(sk, SOCK_DEAD))
2591                 sk->sk_state_change(sk);
2592         else
2593                 inet_csk_destroy_sock(sk);
2594 }
2595 EXPORT_SYMBOL_GPL(tcp_done);
2596
2597 extern struct tcp_congestion_ops tcp_reno;
2598
2599 static __initdata unsigned long thash_entries;
2600 static int __init set_thash_entries(char *str)
2601 {
2602         if (!str)
2603                 return 0;
2604         thash_entries = simple_strtoul(str, &str, 0);
2605         return 1;
2606 }
2607 __setup("thash_entries=", set_thash_entries);
2608
2609 void __init tcp_init(void)
2610 {
2611         struct sk_buff *skb = NULL;
2612         unsigned long limit;
2613         int order, i, max_share;
2614
2615         BUILD_BUG_ON(sizeof(struct tcp_skb_cb) > sizeof(skb->cb));
2616
2617         tcp_hashinfo.bind_bucket_cachep =
2618                 kmem_cache_create("tcp_bind_bucket",
2619                                   sizeof(struct inet_bind_bucket), 0,
2620                                   SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
2621
2622         /* Size and allocate the main established and bind bucket
2623          * hash tables.
2624          *
2625          * The methodology is similar to that of the buffer cache.
2626          */
2627         tcp_hashinfo.ehash =
2628                 alloc_large_system_hash("TCP established",
2629                                         sizeof(struct inet_ehash_bucket),
2630                                         thash_entries,
2631                                         (num_physpages >= 128 * 1024) ?
2632                                         13 : 15,
2633                                         0,
2634                                         &tcp_hashinfo.ehash_size,
2635                                         NULL,
2636                                         thash_entries ? 0 : 512 * 1024);
2637         tcp_hashinfo.ehash_size = 1 << tcp_hashinfo.ehash_size;
2638         for (i = 0; i < tcp_hashinfo.ehash_size; i++) {
2639                 INIT_HLIST_HEAD(&tcp_hashinfo.ehash[i].chain);
2640                 INIT_HLIST_HEAD(&tcp_hashinfo.ehash[i].twchain);
2641         }
2642         if (inet_ehash_locks_alloc(&tcp_hashinfo))
2643                 panic("TCP: failed to alloc ehash_locks");
2644         tcp_hashinfo.bhash =
2645                 alloc_large_system_hash("TCP bind",
2646                                         sizeof(struct inet_bind_hashbucket),
2647                                         tcp_hashinfo.ehash_size,
2648                                         (num_physpages >= 128 * 1024) ?
2649                                         13 : 15,
2650                                         0,
2651                                         &tcp_hashinfo.bhash_size,
2652                                         NULL,
2653                                         64 * 1024);
2654         tcp_hashinfo.bhash_size = 1 << tcp_hashinfo.bhash_size;
2655         for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
2656                 spin_lock_init(&tcp_hashinfo.bhash[i].lock);
2657                 INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
2658         }
2659
2660         /* Try to be a bit smarter and adjust defaults depending
2661          * on available memory.
2662          */
2663         for (order = 0; ((1 << order) << PAGE_SHIFT) <
2664                         (tcp_hashinfo.bhash_size * sizeof(struct inet_bind_hashbucket));
2665                         order++)
2666                 ;
2667         if (order >= 4) {
2668                 tcp_death_row.sysctl_max_tw_buckets = 180000;
2669                 sysctl_tcp_max_orphans = 4096 << (order - 4);
2670                 sysctl_max_syn_backlog = 1024;
2671         } else if (order < 3) {
2672                 tcp_death_row.sysctl_max_tw_buckets >>= (3 - order);
2673                 sysctl_tcp_max_orphans >>= (3 - order);
2674                 sysctl_max_syn_backlog = 128;
2675         }
2676
2677         /* Set the pressure threshold to be a fraction of global memory that
2678          * is up to 1/2 at 256 MB, decreasing toward zero with the amount of
2679          * memory, with a floor of 128 pages.
2680          */
2681         limit = min(nr_all_pages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT);
2682         limit = (limit * (nr_all_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
2683         limit = max(limit, 128UL);
2684         sysctl_tcp_mem[0] = limit / 4 * 3;
2685         sysctl_tcp_mem[1] = limit;
2686         sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2;
2687
2688         /* Set per-socket limits to no more than 1/128 the pressure threshold */
2689         limit = ((unsigned long)sysctl_tcp_mem[1]) << (PAGE_SHIFT - 7);
2690         max_share = min(4UL*1024*1024, limit);
2691
2692         sysctl_tcp_wmem[0] = SK_MEM_QUANTUM;
2693         sysctl_tcp_wmem[1] = 16*1024;
2694         sysctl_tcp_wmem[2] = max(64*1024, max_share);
2695
2696         sysctl_tcp_rmem[0] = SK_MEM_QUANTUM;
2697         sysctl_tcp_rmem[1] = 87380;
2698         sysctl_tcp_rmem[2] = max(87380, max_share);
2699
2700         printk(KERN_INFO "TCP: Hash tables configured "
2701                "(established %d bind %d)\n",
2702                tcp_hashinfo.ehash_size, tcp_hashinfo.bhash_size);
2703
2704         tcp_register_congestion_control(&tcp_reno);
2705 }
2706
2707 EXPORT_SYMBOL(tcp_close);
2708 EXPORT_SYMBOL(tcp_disconnect);
2709 EXPORT_SYMBOL(tcp_getsockopt);
2710 EXPORT_SYMBOL(tcp_ioctl);
2711 EXPORT_SYMBOL(tcp_poll);
2712 EXPORT_SYMBOL(tcp_read_sock);
2713 EXPORT_SYMBOL(tcp_recvmsg);
2714 EXPORT_SYMBOL(tcp_sendmsg);
2715 EXPORT_SYMBOL(tcp_splice_read);
2716 EXPORT_SYMBOL(tcp_sendpage);
2717 EXPORT_SYMBOL(tcp_setsockopt);
2718 EXPORT_SYMBOL(tcp_shutdown);
2719 EXPORT_SYMBOL(tcp_statistics);