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/config.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/smp_lock.h>
 257 #include <linux/fs.h>
 258 #include <linux/random.h>
 259 #include <linux/bootmem.h>
 260 #include <linux/cache.h>
 261
 262 #include <net/icmp.h>
 263 #include <net/tcp.h>
 264 #include <net/xfrm.h>
 265 #include <net/ip.h>
 266
 267
 268 #include <asm/uaccess.h>
 269 #include <asm/ioctls.h>
 270
 271 int sysctl_tcp_fin_timeout = TCP_FIN_TIMEOUT;
 272
 273 DEFINE_SNMP_STAT(struct tcp_mib, tcp_statistics) __read_mostly;
 274
 275 atomic_t tcp_orphan_count = ATOMIC_INIT(0);
 276
 277 EXPORT_SYMBOL_GPL(tcp_orphan_count);
 278
 279 int sysctl_tcp_mem[3] __read_mostly;
 280 int sysctl_tcp_wmem[3] __read_mostly;
 281 int sysctl_tcp_rmem[3] __read_mostly;
 282
 283 EXPORT_SYMBOL(sysctl_tcp_mem);
 284 EXPORT_SYMBOL(sysctl_tcp_rmem);
 285 EXPORT_SYMBOL(sysctl_tcp_wmem);
 286
 287 atomic_t tcp_memory_allocated;  /* Current allocated memory. */
 288 atomic_t tcp_sockets_allocated; /* Current number of TCP sockets. */
 289
 290 EXPORT_SYMBOL(tcp_memory_allocated);
 291 EXPORT_SYMBOL(tcp_sockets_allocated);
 292
 293 /*
 294  * Pressure flag: try to collapse.
 295  * Technical note: it is used by multiple contexts non atomically.
 296  * All the sk_stream_mem_schedule() is of this nature: accounting
 297  * is strict, actions are advisory and have some latency.
 298  */
 299 int tcp_memory_pressure;
 300
 301 EXPORT_SYMBOL(tcp_memory_pressure);
 302
 303 void tcp_enter_memory_pressure(void)
 304 {
 305         if (!tcp_memory_pressure) {
 306                 NET_INC_STATS(LINUX_MIB_TCPMEMORYPRESSURES);
 307                 tcp_memory_pressure = 1;
 308         }
 309 }
 310
 311 EXPORT_SYMBOL(tcp_enter_memory_pressure);
 312
 313 /*
 314  *      Wait for a TCP event.
 315  *
 316  *      Note that we don't need to lock the socket, as the upper poll layers
 317  *      take care of normal races (between the test and the event) and we don't
 318  *      go look at any of the socket buffers directly.
 319  */
 320 unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
 321 {
 322         unsigned int mask;
 323         struct sock *sk = sock->sk;
 324         struct tcp_sock *tp = tcp_sk(sk);
 325
 326         poll_wait(file, sk->sk_sleep, wait);
 327         if (sk->sk_state == TCP_LISTEN)
 328                 return inet_csk_listen_poll(sk);
 329
 330         /* Socket is not locked. We are protected from async events
 331            by poll logic and correct handling of state changes
 332            made by another threads is impossible in any case.
 333          */
 334
 335         mask = 0;
 336         if (sk->sk_err)
 337                 mask = POLLERR;
 338
 339         /*
 340          * POLLHUP is certainly not done right. But poll() doesn't
 341          * have a notion of HUP in just one direction, and for a
 342          * socket the read side is more interesting.
 343          *
 344          * Some poll() documentation says that POLLHUP is incompatible
 345          * with the POLLOUT/POLLWR flags, so somebody should check this
 346          * all. But careful, it tends to be safer to return too many
 347          * bits than too few, and you can easily break real applications
 348          * if you don't tell them that something has hung up!
 349          *
 350          * Check-me.
 351          *
 352          * Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and
 353          * our fs/select.c). It means that after we received EOF,
 354          * poll always returns immediately, making impossible poll() on write()
 355          * in state CLOSE_WAIT. One solution is evident --- to set POLLHUP
 356          * if and only if shutdown has been made in both directions.
 357          * Actually, it is interesting to look how Solaris and DUX
 358          * solve this dilemma. I would prefer, if PULLHUP were maskable,
 359          * then we could set it on SND_SHUTDOWN. BTW examples given
 360          * in Stevens' books assume exactly this behaviour, it explains
 361          * why PULLHUP is incompatible with POLLOUT.    --ANK
 362          *
 363          * NOTE. Check for TCP_CLOSE is added. The goal is to prevent
 364          * blocking on fresh not-connected or disconnected socket. --ANK
 365          */
 366         if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == TCP_CLOSE)
 367                 mask |= POLLHUP;
 368         if (sk->sk_shutdown & RCV_SHUTDOWN)
 369                 mask |= POLLIN | POLLRDNORM | POLLRDHUP;
 370
 371         /* Connected? */
 372         if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV)) {
 373                 /* Potential race condition. If read of tp below will
 374                  * escape above sk->sk_state, we can be illegally awaken
 375                  * in SYN_* states. */
 376                 if ((tp->rcv_nxt != tp->copied_seq) &&
 377                     (tp->urg_seq != tp->copied_seq ||
 378                      tp->rcv_nxt != tp->copied_seq + 1 ||
 379                      sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data))
 380                         mask |= POLLIN | POLLRDNORM;
 381
 382                 if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
 383                         if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
 384                                 mask |= POLLOUT | POLLWRNORM;
 385                         } else {  /* send SIGIO later */
 386                                 set_bit(SOCK_ASYNC_NOSPACE,
 387                                         &sk->sk_socket->flags);
 388                                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 389
 390                                 /* Race breaker. If space is freed after
 391                                  * wspace test but before the flags are set,
 392                                  * IO signal will be lost.
 393                                  */
 394                                 if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk))
 395                                         mask |= POLLOUT | POLLWRNORM;
 396                         }
 397                 }
 398
 399                 if (tp->urg_data & TCP_URG_VALID)
 400                         mask |= POLLPRI;
 401         }
 402         return mask;
 403 }
 404
 405 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
 406 {
 407         struct tcp_sock *tp = tcp_sk(sk);
 408         int answ;
 409
 410         switch (cmd) {
 411         case SIOCINQ:
 412                 if (sk->sk_state == TCP_LISTEN)
 413                         return -EINVAL;
 414
 415                 lock_sock(sk);
 416                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
 417                         answ = 0;
 418                 else if (sock_flag(sk, SOCK_URGINLINE) ||
 419                          !tp->urg_data ||
 420                          before(tp->urg_seq, tp->copied_seq) ||
 421                          !before(tp->urg_seq, tp->rcv_nxt)) {
 422                         answ = tp->rcv_nxt - tp->copied_seq;
 423
 424                         /* Subtract 1, if FIN is in queue. */
 425                         if (answ && !skb_queue_empty(&sk->sk_receive_queue))
 426                                 answ -=
 427                        ((struct sk_buff *)sk->sk_receive_queue.prev)->h.th->fin;
 428                 } else
 429                         answ = tp->urg_seq - tp->copied_seq;
 430                 release_sock(sk);
 431                 break;
 432         case SIOCATMARK:
 433                 answ = tp->urg_data && tp->urg_seq == tp->copied_seq;
 434                 break;
 435         case SIOCOUTQ:
 436                 if (sk->sk_state == TCP_LISTEN)
 437                         return -EINVAL;
 438
 439                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
 440                         answ = 0;
 441                 else
 442                         answ = tp->write_seq - tp->snd_una;
 443                 break;
 444         default:
 445                 return -ENOIOCTLCMD;
 446         };
 447
 448         return put_user(answ, (int __user *)arg);
 449 }
 450
 451 static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
 452 {
 453         TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH;
 454         tp->pushed_seq = tp->write_seq;
 455 }
 456
 457 static inline int forced_push(struct tcp_sock *tp)
 458 {
 459         return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
 460 }
 461
 462 static inline void skb_entail(struct sock *sk, struct tcp_sock *tp,
 463                               struct sk_buff *skb)
 464 {
 465         skb->csum = 0;
 466         TCP_SKB_CB(skb)->seq = tp->write_seq;
 467         TCP_SKB_CB(skb)->end_seq = tp->write_seq;
 468         TCP_SKB_CB(skb)->flags = TCPCB_FLAG_ACK;
 469         TCP_SKB_CB(skb)->sacked = 0;
 470         skb_header_release(skb);
 471         __skb_queue_tail(&sk->sk_write_queue, skb);
 472         sk_charge_skb(sk, skb);
 473         if (!sk->sk_send_head)
 474                 sk->sk_send_head = skb;
 475         if (tp->nonagle & TCP_NAGLE_PUSH)
 476                 tp->nonagle &= ~TCP_NAGLE_PUSH;
 477 }
 478
 479 static inline void tcp_mark_urg(struct tcp_sock *tp, int flags,
 480                                 struct sk_buff *skb)
 481 {
 482         if (flags & MSG_OOB) {
 483                 tp->urg_mode = 1;
 484                 tp->snd_up = tp->write_seq;
 485                 TCP_SKB_CB(skb)->sacked |= TCPCB_URG;
 486         }
 487 }
 488
 489 static inline void tcp_push(struct sock *sk, struct tcp_sock *tp, int flags,
 490                             int mss_now, int nonagle)
 491 {
 492         if (sk->sk_send_head) {
 493                 struct sk_buff *skb = sk->sk_write_queue.prev;
 494                 if (!(flags & MSG_MORE) || forced_push(tp))
 495                         tcp_mark_push(tp, skb);
 496                 tcp_mark_urg(tp, flags, skb);
 497                 __tcp_push_pending_frames(sk, tp, mss_now,
 498                                           (flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle);
 499         }
 500 }
 501
 502 static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset,
 503                          size_t psize, int flags)
 504 {
 505         struct tcp_sock *tp = tcp_sk(sk);
 506         int mss_now, size_goal;
 507         int err;
 508         ssize_t copied;
 509         long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 510
 511         /* Wait for a connection to finish. */
 512         if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
 513                 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
 514                         goto out_err;
 515
 516         clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 517
 518         mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
 519         size_goal = tp->xmit_size_goal;
 520         copied = 0;
 521
 522         err = -EPIPE;
 523         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 524                 goto do_error;
 525
 526         while (psize > 0) {
 527                 struct sk_buff *skb = sk->sk_write_queue.prev;
 528                 struct page *page = pages[poffset / PAGE_SIZE];
 529                 int copy, i, can_coalesce;
 530                 int offset = poffset % PAGE_SIZE;
 531                 int size = min_t(size_t, psize, PAGE_SIZE - offset);
 532
 533                 if (!sk->sk_send_head || (copy = size_goal - skb->len) <= 0) {
 534 new_segment:
 535                         if (!sk_stream_memory_free(sk))
 536                                 goto wait_for_sndbuf;
 537
 538                         skb = sk_stream_alloc_pskb(sk, 0, 0,
 539                                                    sk->sk_allocation);
 540                         if (!skb)
 541                                 goto wait_for_memory;
 542
 543                         skb_entail(sk, tp, skb);
 544                         copy = size_goal;
 545                 }
 546
 547                 if (copy > size)
 548                         copy = size;
 549
 550                 i = skb_shinfo(skb)->nr_frags;
 551                 can_coalesce = skb_can_coalesce(skb, i, page, offset);
 552                 if (!can_coalesce && i >= MAX_SKB_FRAGS) {
 553                         tcp_mark_push(tp, skb);
 554                         goto new_segment;
 555                 }
 556                 if (!sk_stream_wmem_schedule(sk, copy))
 557                         goto wait_for_memory;
 558
 559                 if (can_coalesce) {
 560                         skb_shinfo(skb)->frags[i - 1].size += copy;
 561                 } else {
 562                         get_page(page);
 563                         skb_fill_page_desc(skb, i, page, offset, copy);
 564                 }
 565
 566                 skb->len += copy;
 567                 skb->data_len += copy;
 568                 skb->truesize += copy;
 569                 sk->sk_wmem_queued += copy;
 570                 sk->sk_forward_alloc -= copy;
 571                 skb->ip_summed = CHECKSUM_HW;
 572                 tp->write_seq += copy;
 573                 TCP_SKB_CB(skb)->end_seq += copy;
 574                 skb_shinfo(skb)->tso_segs = 0;
 575
 576                 if (!copied)
 577                         TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
 578
 579                 copied += copy;
 580                 poffset += copy;
 581                 if (!(psize -= copy))
 582                         goto out;
 583
 584                 if (skb->len < mss_now || (flags & MSG_OOB))
 585                         continue;
 586
 587                 if (forced_push(tp)) {
 588                         tcp_mark_push(tp, skb);
 589                         __tcp_push_pending_frames(sk, tp, mss_now, TCP_NAGLE_PUSH);
 590                 } else if (skb == sk->sk_send_head)
 591                         tcp_push_one(sk, mss_now);
 592                 continue;
 593
 594 wait_for_sndbuf:
 595                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 596 wait_for_memory:
 597                 if (copied)
 598                         tcp_push(sk, tp, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
 599
 600                 if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
 601                         goto do_error;
 602
 603                 mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
 604                 size_goal = tp->xmit_size_goal;
 605         }
 606
 607 out:
 608         if (copied)
 609                 tcp_push(sk, tp, flags, mss_now, tp->nonagle);
 610         return copied;
 611
 612 do_error:
 613         if (copied)
 614                 goto out;
 615 out_err:
 616         return sk_stream_error(sk, flags, err);
 617 }
 618
 619 ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset,
 620                      size_t size, int flags)
 621 {
 622         ssize_t res;
 623         struct sock *sk = sock->sk;
 624
 625 #define TCP_ZC_CSUM_FLAGS (NETIF_F_IP_CSUM | NETIF_F_NO_CSUM | NETIF_F_HW_CSUM)
 626
 627         if (!(sk->sk_route_caps & NETIF_F_SG) ||
 628             !(sk->sk_route_caps & TCP_ZC_CSUM_FLAGS))
 629                 return sock_no_sendpage(sock, page, offset, size, flags);
 630
 631 #undef TCP_ZC_CSUM_FLAGS
 632
 633         lock_sock(sk);
 634         TCP_CHECK_TIMER(sk);
 635         res = do_tcp_sendpages(sk, &page, offset, size, flags);
 636         TCP_CHECK_TIMER(sk);
 637         release_sock(sk);
 638         return res;
 639 }
 640
 641 #define TCP_PAGE(sk)    (sk->sk_sndmsg_page)
 642 #define TCP_OFF(sk)     (sk->sk_sndmsg_off)
 643
 644 static inline int select_size(struct sock *sk, struct tcp_sock *tp)
 645 {
 646         int tmp = tp->mss_cache;
 647
 648         if (sk->sk_route_caps & NETIF_F_SG) {
 649                 if (sk->sk_route_caps & NETIF_F_TSO)
 650                         tmp = 0;
 651                 else {
 652                         int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
 653
 654                         if (tmp >= pgbreak &&
 655                             tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
 656                                 tmp = pgbreak;
 657                 }
 658         }
 659
 660         return tmp;
 661 }
 662
 663 int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 664                 size_t size)
 665 {
 666         struct iovec *iov;
 667         struct tcp_sock *tp = tcp_sk(sk);
 668         struct sk_buff *skb;
 669         int iovlen, flags;
 670         int mss_now, size_goal;
 671         int err, copied;
 672         long timeo;
 673
 674         lock_sock(sk);
 675         TCP_CHECK_TIMER(sk);
 676
 677         flags = msg->msg_flags;
 678         timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 679
 680         /* Wait for a connection to finish. */
 681         if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
 682                 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
 683                         goto out_err;
 684
 685         /* This should be in poll */
 686         clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 687
 688         mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
 689         size_goal = tp->xmit_size_goal;
 690
 691         /* Ok commence sending. */
 692         iovlen = msg->msg_iovlen;
 693         iov = msg->msg_iov;
 694         copied = 0;
 695
 696         err = -EPIPE;
 697         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 698                 goto do_error;
 699
 700         while (--iovlen >= 0) {
 701                 int seglen = iov->iov_len;
 702                 unsigned char __user *from = iov->iov_base;
 703
 704                 iov++;
 705
 706                 while (seglen > 0) {
 707                         int copy;
 708
 709                         skb = sk->sk_write_queue.prev;
 710
 711                         if (!sk->sk_send_head ||
 712                             (copy = size_goal - skb->len) <= 0) {
 713
 714 new_segment:
 715                                 /* Allocate new segment. If the interface is SG,
 716                                  * allocate skb fitting to single page.
 717                                  */
 718                                 if (!sk_stream_memory_free(sk))
 719                                         goto wait_for_sndbuf;
 720
 721                                 skb = sk_stream_alloc_pskb(sk, select_size(sk, tp),
 722                                                            0, sk->sk_allocation);
 723                                 if (!skb)
 724                                         goto wait_for_memory;
 725
 726                                 /*
 727                                  * Check whether we can use HW checksum.
 728                                  */
 729                                 if (sk->sk_route_caps &
 730                                     (NETIF_F_IP_CSUM | NETIF_F_NO_CSUM |
 731                                      NETIF_F_HW_CSUM))
 732                                         skb->ip_summed = CHECKSUM_HW;
 733
 734                                 skb_entail(sk, tp, skb);
 735                                 copy = size_goal;
 736                         }
 737
 738                         /* Try to append data to the end of skb. */
 739                         if (copy > seglen)
 740                                 copy = seglen;
 741
 742                         /* Where to copy to? */
 743                         if (skb_tailroom(skb) > 0) {
 744                                 /* We have some space in skb head. Superb! */
 745                                 if (copy > skb_tailroom(skb))
 746                                         copy = skb_tailroom(skb);
 747                                 if ((err = skb_add_data(skb, from, copy)) != 0)
 748                                         goto do_fault;
 749                         } else {
 750                                 int merge = 0;
 751                                 int i = skb_shinfo(skb)->nr_frags;
 752                                 struct page *page = TCP_PAGE(sk);
 753                                 int off = TCP_OFF(sk);
 754
 755                                 if (skb_can_coalesce(skb, i, page, off) &&
 756                                     off != PAGE_SIZE) {
 757                                         /* We can extend the last page
 758                                          * fragment. */
 759                                         merge = 1;
 760                                 } else if (i == MAX_SKB_FRAGS ||
 761                                            (!i &&
 762                                            !(sk->sk_route_caps & NETIF_F_SG))) {
 763                                         /* Need to add new fragment and cannot
 764                                          * do this because interface is non-SG,
 765                                          * or because all the page slots are
 766                                          * busy. */
 767                                         tcp_mark_push(tp, skb);
 768                                         goto new_segment;
 769                                 } else if (page) {
 770                                         if (off == PAGE_SIZE) {
 771                                                 put_page(page);
 772                                                 TCP_PAGE(sk) = page = NULL;
 773                                                 off = 0;
 774                                         }
 775                                 } else
 776                                         off = 0;
 777
 778                                 if (copy > PAGE_SIZE - off)
 779                                         copy = PAGE_SIZE - off;
 780
 781                                 if (!sk_stream_wmem_schedule(sk, copy))
 782                                         goto wait_for_memory;
 783
 784                                 if (!page) {
 785                                         /* Allocate new cache page. */
 786                                         if (!(page = sk_stream_alloc_page(sk)))
 787                                                 goto wait_for_memory;
 788                                 }
 789
 790                                 /* Time to copy data. We are close to
 791                                  * the end! */
 792                                 err = skb_copy_to_page(sk, from, skb, page,
 793                                                        off, copy);
 794                                 if (err) {
 795                                         /* If this page was new, give it to the
 796                                          * socket so it does not get leaked.
 797                                          */
 798                                         if (!TCP_PAGE(sk)) {
 799                                                 TCP_PAGE(sk) = page;
 800                                                 TCP_OFF(sk) = 0;
 801                                         }
 802                                         goto do_error;
 803                                 }
 804
 805                                 /* Update the skb. */
 806                                 if (merge) {
 807                                         skb_shinfo(skb)->frags[i - 1].size +=
 808                                                                         copy;
 809                                 } else {
 810                                         skb_fill_page_desc(skb, i, page, off, copy);
 811                                         if (TCP_PAGE(sk)) {
 812                                                 get_page(page);
 813                                         } else if (off + copy < PAGE_SIZE) {
 814                                                 get_page(page);
 815                                                 TCP_PAGE(sk) = page;
 816                                         }
 817                                 }
 818
 819                                 TCP_OFF(sk) = off + copy;
 820                         }
 821
 822                         if (!copied)
 823                                 TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
 824
 825                         tp->write_seq += copy;
 826                         TCP_SKB_CB(skb)->end_seq += copy;
 827                         skb_shinfo(skb)->tso_segs = 0;
 828
 829                         from += copy;
 830                         copied += copy;
 831                         if ((seglen -= copy) == 0 && iovlen == 0)
 832                                 goto out;
 833
 834                         if (skb->len < mss_now || (flags & MSG_OOB))
 835                                 continue;
 836
 837                         if (forced_push(tp)) {
 838                                 tcp_mark_push(tp, skb);
 839                                 __tcp_push_pending_frames(sk, tp, mss_now, TCP_NAGLE_PUSH);
 840                         } else if (skb == sk->sk_send_head)
 841                                 tcp_push_one(sk, mss_now);
 842                         continue;
 843
 844 wait_for_sndbuf:
 845                         set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 846 wait_for_memory:
 847                         if (copied)
 848                                 tcp_push(sk, tp, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
 849
 850                         if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
 851                                 goto do_error;
 852
 853                         mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
 854                         size_goal = tp->xmit_size_goal;
 855                 }
 856         }
 857
 858 out:
 859         if (copied)
 860                 tcp_push(sk, tp, flags, mss_now, tp->nonagle);
 861         TCP_CHECK_TIMER(sk);
 862         release_sock(sk);
 863         return copied;
 864
 865 do_fault:
 866         if (!skb->len) {
 867                 if (sk->sk_send_head == skb)
 868                         sk->sk_send_head = NULL;
 869                 __skb_unlink(skb, &sk->sk_write_queue);
 870                 sk_stream_free_skb(sk, skb);
 871         }
 872
 873 do_error:
 874         if (copied)
 875                 goto out;
 876 out_err:
 877         err = sk_stream_error(sk, flags, err);
 878         TCP_CHECK_TIMER(sk);
 879         release_sock(sk);
 880         return err;
 881 }
 882
 883 /*
 884  *      Handle reading urgent data. BSD has very simple semantics for
 885  *      this, no blocking and very strange errors 8)
 886  */
 887
 888 static int tcp_recv_urg(struct sock *sk, long timeo,
 889                         struct msghdr *msg, int len, int flags,
 890                         int *addr_len)
 891 {
 892         struct tcp_sock *tp = tcp_sk(sk);
 893
 894         /* No URG data to read. */
 895         if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
 896             tp->urg_data == TCP_URG_READ)
 897                 return -EINVAL; /* Yes this is right ! */
 898
 899         if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
 900                 return -ENOTCONN;
 901
 902         if (tp->urg_data & TCP_URG_VALID) {
 903                 int err = 0;
 904                 char c = tp->urg_data;
 905
 906                 if (!(flags & MSG_PEEK))
 907                         tp->urg_data = TCP_URG_READ;
 908
 909                 /* Read urgent data. */
 910                 msg->msg_flags |= MSG_OOB;
 911
 912                 if (len > 0) {
 913                         if (!(flags & MSG_TRUNC))
 914                                 err = memcpy_toiovec(msg->msg_iov, &c, 1);
 915                         len = 1;
 916                 } else
 917                         msg->msg_flags |= MSG_TRUNC;
 918
 919                 return err ? -EFAULT : len;
 920         }
 921
 922         if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
 923                 return 0;
 924
 925         /* Fixed the recv(..., MSG_OOB) behaviour.  BSD docs and
 926          * the available implementations agree in this case:
 927          * this call should never block, independent of the
 928          * blocking state of the socket.
 929          * Mike <pall@rz.uni-karlsruhe.de>
 930          */
 931         return -EAGAIN;
 932 }
 933
 934 /* Clean up the receive buffer for full frames taken by the user,
 935  * then send an ACK if necessary.  COPIED is the number of bytes
 936  * tcp_recvmsg has given to the user so far, it speeds up the
 937  * calculation of whether or not we must ACK for the sake of
 938  * a window update.
 939  */
 940 static void cleanup_rbuf(struct sock *sk, int copied)
 941 {
 942         struct tcp_sock *tp = tcp_sk(sk);
 943         int time_to_ack = 0;
 944
 945 #if TCP_DEBUG
 946         struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
 947
 948         BUG_TRAP(!skb || before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq));
 949 #endif
 950
 951         if (inet_csk_ack_scheduled(sk)) {
 952                 const struct inet_connection_sock *icsk = inet_csk(sk);
 953                    /* Delayed ACKs frequently hit locked sockets during bulk
 954                     * receive. */
 955                 if (icsk->icsk_ack.blocked ||
 956                     /* Once-per-two-segments ACK was not sent by tcp_input.c */
 957                     tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
 958                     /*
 959                      * If this read emptied read buffer, we send ACK, if
 960                      * connection is not bidirectional, user drained
 961                      * receive buffer and there was a small segment
 962                      * in queue.
 963                      */
 964                     (copied > 0 && (icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
 965                      !icsk->icsk_ack.pingpong && !atomic_read(&sk->sk_rmem_alloc)))
 966                         time_to_ack = 1;
 967         }
 968
 969         /* We send an ACK if we can now advertise a non-zero window
 970          * which has been raised "significantly".
 971          *
 972          * Even if window raised up to infinity, do not send window open ACK
 973          * in states, where we will not receive more. It is useless.
 974          */
 975         if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
 976                 __u32 rcv_window_now = tcp_receive_window(tp);
 977
 978                 /* Optimize, __tcp_select_window() is not cheap. */
 979                 if (2*rcv_window_now <= tp->window_clamp) {
 980                         __u32 new_window = __tcp_select_window(sk);
 981
 982                         /* Send ACK now, if this read freed lots of space
 983                          * in our buffer. Certainly, new_window is new window.
 984                          * We can advertise it now, if it is not less than current one.
 985                          * "Lots" means "at least twice" here.
 986                          */
 987                         if (new_window && new_window >= 2 * rcv_window_now)
 988                                 time_to_ack = 1;
 989                 }
 990         }
 991         if (time_to_ack)
 992                 tcp_send_ack(sk);
 993 }
 994
 995 static void tcp_prequeue_process(struct sock *sk)
 996 {
 997         struct sk_buff *skb;
 998         struct tcp_sock *tp = tcp_sk(sk);
 999
1000         NET_INC_STATS_USER(LINUX_MIB_TCPPREQUEUED);
1001
1002         /* RX process wants to run with disabled BHs, though it is not
1003          * necessary */
1004         local_bh_disable();
1005         while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)
1006                 sk->sk_backlog_rcv(sk, skb);
1007         local_bh_enable();
1008
1009         /* Clear memory counter. */
1010         tp->ucopy.memory = 0;
1011 }
1012
1013 static inline struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
1014 {
1015         struct sk_buff *skb;
1016         u32 offset;
1017
1018         skb_queue_walk(&sk->sk_receive_queue, skb) {
1019                 offset = seq - TCP_SKB_CB(skb)->seq;
1020                 if (skb->h.th->syn)
1021                         offset--;
1022                 if (offset < skb->len || skb->h.th->fin) {
1023                         *off = offset;
1024                         return skb;
1025                 }
1026         }
1027         return NULL;
1028 }
1029
1030 /*
1031  * This routine provides an alternative to tcp_recvmsg() for routines
1032  * that would like to handle copying from skbuffs directly in 'sendfile'
1033  * fashion.
1034  * Note:
1035  *      - It is assumed that the socket was locked by the caller.
1036  *      - The routine does not block.
1037  *      - At present, there is no support for reading OOB data
1038  *        or for 'peeking' the socket using this routine
1039  *        (although both would be easy to implement).
1040  */
1041 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
1042                   sk_read_actor_t recv_actor)
1043 {
1044         struct sk_buff *skb;
1045         struct tcp_sock *tp = tcp_sk(sk);
1046         u32 seq = tp->copied_seq;
1047         u32 offset;
1048         int copied = 0;
1049
1050         if (sk->sk_state == TCP_LISTEN)
1051                 return -ENOTCONN;
1052         while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
1053                 if (offset < skb->len) {
1054                         size_t used, len;
1055
1056                         len = skb->len - offset;
1057                         /* Stop reading if we hit a patch of urgent data */
1058                         if (tp->urg_data) {
1059                                 u32 urg_offset = tp->urg_seq - seq;
1060                                 if (urg_offset < len)
1061                                         len = urg_offset;
1062                                 if (!len)
1063                                         break;
1064                         }
1065                         used = recv_actor(desc, skb, offset, len);
1066                         if (used <= len) {
1067                                 seq += used;
1068                                 copied += used;
1069                                 offset += used;
1070                         }
1071                         if (offset != skb->len)
1072                                 break;
1073                 }
1074                 if (skb->h.th->fin) {
1075                         sk_eat_skb(sk, skb);
1076                         ++seq;
1077                         break;
1078                 }
1079                 sk_eat_skb(sk, skb);
1080                 if (!desc->count)
1081                         break;
1082         }
1083         tp->copied_seq = seq;
1084
1085         tcp_rcv_space_adjust(sk);
1086
1087         /* Clean up data we have read: This will do ACK frames. */
1088         if (copied)
1089                 cleanup_rbuf(sk, copied);
1090         return copied;
1091 }
1092
1093 /*
1094  *      This routine copies from a sock struct into the user buffer.
1095  *
1096  *      Technical note: in 2.3 we work on _locked_ socket, so that
1097  *      tricks with *seq access order and skb->users are not required.
1098  *      Probably, code can be easily improved even more.
1099  */
1100
1101 int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
1102                 size_t len, int nonblock, int flags, int *addr_len)
1103 {
1104         struct tcp_sock *tp = tcp_sk(sk);
1105         int copied = 0;
1106         u32 peek_seq;
1107         u32 *seq;
1108         unsigned long used;
1109         int err;
1110         int target;             /* Read at least this many bytes */
1111         long timeo;
1112         struct task_struct *user_recv = NULL;
1113
1114         lock_sock(sk);
1115
1116         TCP_CHECK_TIMER(sk);
1117
1118         err = -ENOTCONN;
1119         if (sk->sk_state == TCP_LISTEN)
1120                 goto out;
1121
1122         timeo = sock_rcvtimeo(sk, nonblock);
1123
1124         /* Urgent data needs to be handled specially. */
1125         if (flags & MSG_OOB)
1126                 goto recv_urg;
1127
1128         seq = &tp->copied_seq;
1129         if (flags & MSG_PEEK) {
1130                 peek_seq = tp->copied_seq;
1131                 seq = &peek_seq;
1132         }
1133
1134         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
1135
1136         do {
1137                 struct sk_buff *skb;
1138                 u32 offset;
1139
1140                 /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
1141                 if (tp->urg_data && tp->urg_seq == *seq) {
1142                         if (copied)
1143                                 break;
1144                         if (signal_pending(current)) {
1145                                 copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
1146                                 break;
1147                         }
1148                 }
1149
1150                 /* Next get a buffer. */
1151
1152                 skb = skb_peek(&sk->sk_receive_queue);
1153                 do {
1154                         if (!skb)
1155                                 break;
1156
1157                         /* Now that we have two receive queues this
1158                          * shouldn't happen.
1159                          */
1160                         if (before(*seq, TCP_SKB_CB(skb)->seq)) {
1161                                 printk(KERN_INFO "recvmsg bug: copied %X "
1162                                        "seq %X\n", *seq, TCP_SKB_CB(skb)->seq);
1163                                 break;
1164                         }
1165                         offset = *seq - TCP_SKB_CB(skb)->seq;
1166                         if (skb->h.th->syn)
1167                                 offset--;
1168                         if (offset < skb->len)
1169                                 goto found_ok_skb;
1170                         if (skb->h.th->fin)
1171                                 goto found_fin_ok;
1172                         BUG_TRAP(flags & MSG_PEEK);
1173                         skb = skb->next;
1174                 } while (skb != (struct sk_buff *)&sk->sk_receive_queue);
1175
1176                 /* Well, if we have backlog, try to process it now yet. */
1177
1178                 if (copied >= target && !sk->sk_backlog.tail)
1179                         break;
1180
1181                 if (copied) {
1182                         if (sk->sk_err ||
1183                             sk->sk_state == TCP_CLOSE ||
1184                             (sk->sk_shutdown & RCV_SHUTDOWN) ||
1185                             !timeo ||
1186                             signal_pending(current) ||
1187                             (flags & MSG_PEEK))
1188                                 break;
1189                 } else {
1190                         if (sock_flag(sk, SOCK_DONE))
1191                                 break;
1192
1193                         if (sk->sk_err) {
1194                                 copied = sock_error(sk);
1195                                 break;
1196                         }
1197
1198                         if (sk->sk_shutdown & RCV_SHUTDOWN)
1199                                 break;
1200
1201                         if (sk->sk_state == TCP_CLOSE) {
1202                                 if (!sock_flag(sk, SOCK_DONE)) {
1203                                         /* This occurs when user tries to read
1204                                          * from never connected socket.
1205                                          */
1206                                         copied = -ENOTCONN;
1207                                         break;
1208                                 }
1209                                 break;
1210                         }
1211
1212                         if (!timeo) {
1213                                 copied = -EAGAIN;
1214                                 break;
1215                         }
1216
1217                         if (signal_pending(current)) {
1218                                 copied = sock_intr_errno(timeo);
1219                                 break;
1220                         }
1221                 }
1222
1223                 cleanup_rbuf(sk, copied);
1224
1225                 if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) {
1226                         /* Install new reader */
1227                         if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) {
1228                                 user_recv = current;
1229                                 tp->ucopy.task = user_recv;
1230                                 tp->ucopy.iov = msg->msg_iov;
1231                         }
1232
1233                         tp->ucopy.len = len;
1234
1235                         BUG_TRAP(tp->copied_seq == tp->rcv_nxt ||
1236                                  (flags & (MSG_PEEK | MSG_TRUNC)));
1237
1238                         /* Ugly... If prequeue is not empty, we have to
1239                          * process it before releasing socket, otherwise
1240                          * order will be broken at second iteration.
1241                          * More elegant solution is required!!!
1242                          *
1243                          * Look: we have the following (pseudo)queues:
1244                          *
1245                          * 1. packets in flight
1246                          * 2. backlog
1247                          * 3. prequeue
1248                          * 4. receive_queue
1249                          *
1250                          * Each queue can be processed only if the next ones
1251                          * are empty. At this point we have empty receive_queue.
1252                          * But prequeue _can_ be not empty after 2nd iteration,
1253                          * when we jumped to start of loop because backlog
1254                          * processing added something to receive_queue.
1255                          * We cannot release_sock(), because backlog contains
1256                          * packets arrived _after_ prequeued ones.
1257                          *
1258                          * Shortly, algorithm is clear --- to process all
1259                          * the queues in order. We could make it more directly,
1260                          * requeueing packets from backlog to prequeue, if
1261                          * is not empty. It is more elegant, but eats cycles,
1262                          * unfortunately.
1263                          */
1264                         if (!skb_queue_empty(&tp->ucopy.prequeue))
1265                                 goto do_prequeue;
1266
1267                         /* __ Set realtime policy in scheduler __ */
1268                 }
1269
1270                 if (copied >= target) {
1271                         /* Do not sleep, just process backlog. */
1272                         release_sock(sk);
1273                         lock_sock(sk);
1274                 } else
1275                         sk_wait_data(sk, &timeo);
1276
1277                 if (user_recv) {
1278                         int chunk;
1279
1280                         /* __ Restore normal policy in scheduler __ */
1281
1282                         if ((chunk = len - tp->ucopy.len) != 0) {
1283                                 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk);
1284                                 len -= chunk;
1285                                 copied += chunk;
1286                         }
1287
1288                         if (tp->rcv_nxt == tp->copied_seq &&
1289                             !skb_queue_empty(&tp->ucopy.prequeue)) {
1290 do_prequeue:
1291                                 tcp_prequeue_process(sk);
1292
1293                                 if ((chunk = len - tp->ucopy.len) != 0) {
1294                                         NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1295                                         len -= chunk;
1296                                         copied += chunk;
1297                                 }
1298                         }
1299                 }
1300                 if ((flags & MSG_PEEK) && peek_seq != tp->copied_seq) {
1301                         if (net_ratelimit())
1302                                 printk(KERN_DEBUG "TCP(%s:%d): Application bug, race in MSG_PEEK.\n",
1303                                        current->comm, current->pid);
1304                         peek_seq = tp->copied_seq;
1305                 }
1306                 continue;
1307
1308         found_ok_skb:
1309                 /* Ok so how much can we use? */
1310                 used = skb->len - offset;
1311                 if (len < used)
1312                         used = len;
1313
1314                 /* Do we have urgent data here? */
1315                 if (tp->urg_data) {
1316                         u32 urg_offset = tp->urg_seq - *seq;
1317                         if (urg_offset < used) {
1318                                 if (!urg_offset) {
1319                                         if (!sock_flag(sk, SOCK_URGINLINE)) {
1320                                                 ++*seq;
1321                                                 offset++;
1322                                                 used--;
1323                                                 if (!used)
1324                                                         goto skip_copy;
1325                                         }
1326                                 } else
1327                                         used = urg_offset;
1328                         }
1329                 }
1330
1331                 if (!(flags & MSG_TRUNC)) {
1332                         err = skb_copy_datagram_iovec(skb, offset,
1333                                                       msg->msg_iov, used);
1334                         if (err) {
1335                                 /* Exception. Bailout! */
1336                                 if (!copied)
1337                                         copied = -EFAULT;
1338                                 break;
1339                         }
1340                 }
1341
1342                 *seq += used;
1343                 copied += used;
1344                 len -= used;
1345
1346                 tcp_rcv_space_adjust(sk);
1347
1348 skip_copy:
1349                 if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) {
1350                         tp->urg_data = 0;
1351                         tcp_fast_path_check(sk, tp);
1352                 }
1353                 if (used + offset < skb->len)
1354                         continue;
1355
1356                 if (skb->h.th->fin)
1357                         goto found_fin_ok;
1358                 if (!(flags & MSG_PEEK))
1359                         sk_eat_skb(sk, skb);
1360                 continue;
1361
1362         found_fin_ok:
1363                 /* Process the FIN. */
1364                 ++*seq;
1365                 if (!(flags & MSG_PEEK))
1366                         sk_eat_skb(sk, skb);
1367                 break;
1368         } while (len > 0);
1369
1370         if (user_recv) {
1371                 if (!skb_queue_empty(&tp->ucopy.prequeue)) {
1372                         int chunk;
1373
1374                         tp->ucopy.len = copied > 0 ? len : 0;
1375
1376                         tcp_prequeue_process(sk);
1377
1378                         if (copied > 0 && (chunk = len - tp->ucopy.len) != 0) {
1379                                 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1380                                 len -= chunk;
1381                                 copied += chunk;
1382                         }
1383                 }
1384
1385                 tp->ucopy.task = NULL;
1386                 tp->ucopy.len = 0;
1387         }
1388
1389         /* According to UNIX98, msg_name/msg_namelen are ignored
1390          * on connected socket. I was just happy when found this 8) --ANK
1391          */
1392
1393         /* Clean up data we have read: This will do ACK frames. */
1394         cleanup_rbuf(sk, copied);
1395
1396         TCP_CHECK_TIMER(sk);
1397         release_sock(sk);
1398         return copied;
1399
1400 out:
1401         TCP_CHECK_TIMER(sk);
1402         release_sock(sk);
1403         return err;
1404
1405 recv_urg:
1406         err = tcp_recv_urg(sk, timeo, msg, len, flags, addr_len);
1407         goto out;
1408 }
1409
1410 /*
1411  *      State processing on a close. This implements the state shift for
1412  *      sending our FIN frame. Note that we only send a FIN for some
1413  *      states. A shutdown() may have already sent the FIN, or we may be
1414  *      closed.
1415  */
1416
1417 static const unsigned char new_state[16] = {
1418   /* current state:        new state:      action:      */
1419   /* (Invalid)          */ TCP_CLOSE,
1420   /* TCP_ESTABLISHED    */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1421   /* TCP_SYN_SENT       */ TCP_CLOSE,
1422   /* TCP_SYN_RECV       */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1423   /* TCP_FIN_WAIT1      */ TCP_FIN_WAIT1,
1424   /* TCP_FIN_WAIT2      */ TCP_FIN_WAIT2,
1425   /* TCP_TIME_WAIT      */ TCP_CLOSE,
1426   /* TCP_CLOSE          */ TCP_CLOSE,
1427   /* TCP_CLOSE_WAIT     */ TCP_LAST_ACK  | TCP_ACTION_FIN,
1428   /* TCP_LAST_ACK       */ TCP_LAST_ACK,
1429   /* TCP_LISTEN         */ TCP_CLOSE,
1430   /* TCP_CLOSING        */ TCP_CLOSING,
1431 };
1432
1433 static int tcp_close_state(struct sock *sk)
1434 {
1435         int next = (int)new_state[sk->sk_state];
1436         int ns = next & TCP_STATE_MASK;
1437
1438         tcp_set_state(sk, ns);
1439
1440         return next & TCP_ACTION_FIN;
1441 }
1442
1443 /*
1444  *      Shutdown the sending side of a connection. Much like close except
1445  *      that we don't receive shut down or set_sock_flag(sk, SOCK_DEAD).
1446  */
1447
1448 void tcp_shutdown(struct sock *sk, int how)
1449 {
1450         /*      We need to grab some memory, and put together a FIN,
1451          *      and then put it into the queue to be sent.
1452          *              Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
1453          */
1454         if (!(how & SEND_SHUTDOWN))
1455                 return;
1456
1457         /* If we've already sent a FIN, or it's a closed state, skip this. */
1458         if ((1 << sk->sk_state) &
1459             (TCPF_ESTABLISHED | TCPF_SYN_SENT |
1460              TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
1461                 /* Clear out any half completed packets.  FIN if needed. */
1462                 if (tcp_close_state(sk))
1463                         tcp_send_fin(sk);
1464         }
1465 }
1466
1467 void tcp_close(struct sock *sk, long timeout)
1468 {
1469         struct sk_buff *skb;
1470         int data_was_unread = 0;
1471
1472         lock_sock(sk);
1473         sk->sk_shutdown = SHUTDOWN_MASK;
1474
1475         if (sk->sk_state == TCP_LISTEN) {
1476                 tcp_set_state(sk, TCP_CLOSE);
1477
1478                 /* Special case. */
1479                 inet_csk_listen_stop(sk);
1480
1481                 goto adjudge_to_death;
1482         }
1483
1484         /*  We need to flush the recv. buffs.  We do this only on the
1485          *  descriptor close, not protocol-sourced closes, because the
1486          *  reader process may not have drained the data yet!
1487          */
1488         while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
1489                 u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq -
1490                           skb->h.th->fin;
1491                 data_was_unread += len;
1492                 __kfree_skb(skb);
1493         }
1494
1495         sk_stream_mem_reclaim(sk);
1496
1497         /* As outlined in draft-ietf-tcpimpl-prob-03.txt, section
1498          * 3.10, we send a RST here because data was lost.  To
1499          * witness the awful effects of the old behavior of always
1500          * doing a FIN, run an older 2.1.x kernel or 2.0.x, start
1501          * a bulk GET in an FTP client, suspend the process, wait
1502          * for the client to advertise a zero window, then kill -9
1503          * the FTP client, wheee...  Note: timeout is always zero
1504          * in such a case.
1505          */
1506         if (data_was_unread) {
1507                 /* Unread data was tossed, zap the connection. */
1508                 NET_INC_STATS_USER(LINUX_MIB_TCPABORTONCLOSE);
1509                 tcp_set_state(sk, TCP_CLOSE);
1510                 tcp_send_active_reset(sk, GFP_KERNEL);
1511         } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
1512                 /* Check zero linger _after_ checking for unread data. */
1513                 sk->sk_prot->disconnect(sk, 0);
1514                 NET_INC_STATS_USER(LINUX_MIB_TCPABORTONDATA);
1515         } else if (tcp_close_state(sk)) {
1516                 /* We FIN if the application ate all the data before
1517                  * zapping the connection.
1518                  */
1519
1520                 /* RED-PEN. Formally speaking, we have broken TCP state
1521                  * machine. State transitions:
1522                  *
1523                  * TCP_ESTABLISHED -> TCP_FIN_WAIT1
1524                  * TCP_SYN_RECV -> TCP_FIN_WAIT1 (forget it, it's impossible)
1525                  * TCP_CLOSE_WAIT -> TCP_LAST_ACK
1526                  *
1527                  * are legal only when FIN has been sent (i.e. in window),
1528                  * rather than queued out of window. Purists blame.
1529                  *
1530                  * F.e. "RFC state" is ESTABLISHED,
1531                  * if Linux state is FIN-WAIT-1, but FIN is still not sent.
1532                  *
1533                  * The visible declinations are that sometimes
1534                  * we enter time-wait state, when it is not required really
1535                  * (harmless), do not send active resets, when they are
1536                  * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when
1537                  * they look as CLOSING or LAST_ACK for Linux)
1538                  * Probably, I missed some more holelets.
1539                  *                                              --ANK
1540                  */
1541                 tcp_send_fin(sk);
1542         }
1543
1544         sk_stream_wait_close(sk, timeout);
1545
1546 adjudge_to_death:
1547         /* It is the last release_sock in its life. It will remove backlog. */
1548         release_sock(sk);
1549
1550
1551         /* Now socket is owned by kernel and we acquire BH lock
1552            to finish close. No need to check for user refs.
1553          */
1554         local_bh_disable();
1555         bh_lock_sock(sk);
1556         BUG_TRAP(!sock_owned_by_user(sk));
1557
1558         sock_hold(sk);
1559         sock_orphan(sk);
1560
1561         /*      This is a (useful) BSD violating of the RFC. There is a
1562          *      problem with TCP as specified in that the other end could
1563          *      keep a socket open forever with no application left this end.
1564          *      We use a 3 minute timeout (about the same as BSD) then kill
1565          *      our end. If they send after that then tough - BUT: long enough
1566          *      that we won't make the old 4*rto = almost no time - whoops
1567          *      reset mistake.
1568          *
1569          *      Nope, it was not mistake. It is really desired behaviour
1570          *      f.e. on http servers, when such sockets are useless, but
1571          *      consume significant resources. Let's do it with special
1572          *      linger2 option.                                 --ANK
1573          */
1574
1575         if (sk->sk_state == TCP_FIN_WAIT2) {
1576                 struct tcp_sock *tp = tcp_sk(sk);
1577                 if (tp->linger2 < 0) {
1578                         tcp_set_state(sk, TCP_CLOSE);
1579                         tcp_send_active_reset(sk, GFP_ATOMIC);
1580                         NET_INC_STATS_BH(LINUX_MIB_TCPABORTONLINGER);
1581                 } else {
1582                         const int tmo = tcp_fin_time(sk);
1583
1584                         if (tmo > TCP_TIMEWAIT_LEN) {
1585                                 inet_csk_reset_keepalive_timer(sk, tcp_fin_time(sk));
1586                         } else {
1587                                 atomic_inc(sk->sk_prot->orphan_count);
1588                                 tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
1589                                 goto out;
1590                         }
1591                 }
1592         }
1593         if (sk->sk_state != TCP_CLOSE) {
1594                 sk_stream_mem_reclaim(sk);
1595                 if (atomic_read(sk->sk_prot->orphan_count) > sysctl_tcp_max_orphans ||
1596                     (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
1597                      atomic_read(&tcp_memory_allocated) > sysctl_tcp_mem[2])) {
1598                         if (net_ratelimit())
1599                                 printk(KERN_INFO "TCP: too many of orphaned "
1600                                        "sockets\n");
1601                         tcp_set_state(sk, TCP_CLOSE);
1602                         tcp_send_active_reset(sk, GFP_ATOMIC);
1603                         NET_INC_STATS_BH(LINUX_MIB_TCPABORTONMEMORY);
1604                 }
1605         }
1606         atomic_inc(sk->sk_prot->orphan_count);
1607
1608         if (sk->sk_state == TCP_CLOSE)
1609                 inet_csk_destroy_sock(sk);
1610         /* Otherwise, socket is reprieved until protocol close. */
1611
1612 out:
1613         bh_unlock_sock(sk);
1614         local_bh_enable();
1615         sock_put(sk);
1616 }
1617
1618 /* These states need RST on ABORT according to RFC793 */
1619
1620 static inline int tcp_need_reset(int state)
1621 {
1622         return (1 << state) &
1623                (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
1624                 TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
1625 }
1626
1627 int tcp_disconnect(struct sock *sk, int flags)
1628 {
1629         struct inet_sock *inet = inet_sk(sk);
1630         struct inet_connection_sock *icsk = inet_csk(sk);
1631         struct tcp_sock *tp = tcp_sk(sk);
1632         int err = 0;
1633         int old_state = sk->sk_state;
1634
1635         if (old_state != TCP_CLOSE)
1636                 tcp_set_state(sk, TCP_CLOSE);
1637
1638         /* ABORT function of RFC793 */
1639         if (old_state == TCP_LISTEN) {
1640                 inet_csk_listen_stop(sk);
1641         } else if (tcp_need_reset(old_state) ||
1642                    (tp->snd_nxt != tp->write_seq &&
1643                     (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
1644                 /* The last check adjusts for discrepancy of Linux wrt. RFC
1645                  * states
1646                  */
1647                 tcp_send_active_reset(sk, gfp_any());
1648                 sk->sk_err = ECONNRESET;
1649         } else if (old_state == TCP_SYN_SENT)
1650                 sk->sk_err = ECONNRESET;
1651
1652         tcp_clear_xmit_timers(sk);
1653         __skb_queue_purge(&sk->sk_receive_queue);
1654         sk_stream_writequeue_purge(sk);
1655         __skb_queue_purge(&tp->out_of_order_queue);
1656
1657         inet->dport = 0;
1658
1659         if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
1660                 inet_reset_saddr(sk);
1661
1662         sk->sk_shutdown = 0;
1663         sock_reset_flag(sk, SOCK_DONE);
1664         tp->srtt = 0;
1665         if ((tp->write_seq += tp->max_window + 2) == 0)
1666                 tp->write_seq = 1;
1667         icsk->icsk_backoff = 0;
1668         tp->snd_cwnd = 2;
1669         icsk->icsk_probes_out = 0;
1670         tp->packets_out = 0;
1671         tp->snd_ssthresh = 0x7fffffff;
1672         tp->snd_cwnd_cnt = 0;
1673         tp->bytes_acked = 0;
1674         tcp_set_ca_state(sk, TCP_CA_Open);
1675         tcp_clear_retrans(tp);
1676         inet_csk_delack_init(sk);
1677         sk->sk_send_head = NULL;
1678         tp->rx_opt.saw_tstamp = 0;
1679         tcp_sack_reset(&tp->rx_opt);
1680         __sk_dst_reset(sk);
1681
1682         BUG_TRAP(!inet->num || icsk->icsk_bind_hash);
1683
1684         sk->sk_error_report(sk);
1685         return err;
1686 }
1687
1688 /*
1689  *      Socket option code for TCP.
1690  */
1691 static int do_tcp_setsockopt(struct sock *sk, int level,
1692                 int optname, char __user *optval, int optlen)
1693 {
1694         struct tcp_sock *tp = tcp_sk(sk);
1695         struct inet_connection_sock *icsk = inet_csk(sk);
1696         int val;
1697         int err = 0;
1698
1699         /* This is a string value all the others are int's */
1700         if (optname == TCP_CONGESTION) {
1701                 char name[TCP_CA_NAME_MAX];
1702
1703                 if (optlen < 1)
1704                         return -EINVAL;
1705
1706                 val = strncpy_from_user(name, optval,
1707                                         min(TCP_CA_NAME_MAX-1, optlen));
1708                 if (val < 0)
1709                         return -EFAULT;
1710                 name[val] = 0;
1711
1712                 lock_sock(sk);
1713                 err = tcp_set_congestion_control(sk, name);
1714                 release_sock(sk);
1715                 return err;
1716         }
1717
1718         if (optlen < sizeof(int))
1719                 return -EINVAL;
1720
1721         if (get_user(val, (int __user *)optval))
1722                 return -EFAULT;
1723
1724         lock_sock(sk);
1725
1726         switch (optname) {
1727         case TCP_MAXSEG:
1728                 /* Values greater than interface MTU won't take effect. However
1729                  * at the point when this call is done we typically don't yet
1730                  * know which interface is going to be used */
1731                 if (val < 8 || val > MAX_TCP_WINDOW) {
1732                         err = -EINVAL;
1733                         break;
1734                 }
1735                 tp->rx_opt.user_mss = val;
1736                 break;
1737
1738         case TCP_NODELAY:
1739                 if (val) {
1740                         /* TCP_NODELAY is weaker than TCP_CORK, so that
1741                          * this option on corked socket is remembered, but
1742                          * it is not activated until cork is cleared.
1743                          *
1744                          * However, when TCP_NODELAY is set we make
1745                          * an explicit push, which overrides even TCP_CORK
1746                          * for currently queued segments.
1747                          */
1748                         tp->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
1749                         tcp_push_pending_frames(sk, tp);
1750                 } else {
1751                         tp->nonagle &= ~TCP_NAGLE_OFF;
1752                 }
1753                 break;
1754
1755         case TCP_CORK:
1756                 /* When set indicates to always queue non-full frames.
1757                  * Later the user clears this option and we transmit
1758                  * any pending partial frames in the queue.  This is
1759                  * meant to be used alongside sendfile() to get properly
1760                  * filled frames when the user (for example) must write
1761                  * out headers with a write() call first and then use
1762                  * sendfile to send out the data parts.
1763                  *
1764                  * TCP_CORK can be set together with TCP_NODELAY and it is
1765                  * stronger than TCP_NODELAY.
1766                  */
1767                 if (val) {
1768                         tp->nonagle |= TCP_NAGLE_CORK;
1769                 } else {
1770                         tp->nonagle &= ~TCP_NAGLE_CORK;
1771                         if (tp->nonagle&TCP_NAGLE_OFF)
1772                                 tp->nonagle |= TCP_NAGLE_PUSH;
1773                         tcp_push_pending_frames(sk, tp);
1774                 }
1775                 break;
1776
1777         case TCP_KEEPIDLE:
1778                 if (val < 1 || val > MAX_TCP_KEEPIDLE)
1779                         err = -EINVAL;
1780                 else {
1781                         tp->keepalive_time = val * HZ;
1782                         if (sock_flag(sk, SOCK_KEEPOPEN) &&
1783                             !((1 << sk->sk_state) &
1784                               (TCPF_CLOSE | TCPF_LISTEN))) {
1785                                 __u32 elapsed = tcp_time_stamp - tp->rcv_tstamp;
1786                                 if (tp->keepalive_time > elapsed)
1787                                         elapsed = tp->keepalive_time - elapsed;
1788                                 else
1789                                         elapsed = 0;
1790                                 inet_csk_reset_keepalive_timer(sk, elapsed);
1791                         }
1792                 }
1793                 break;
1794         case TCP_KEEPINTVL:
1795                 if (val < 1 || val > MAX_TCP_KEEPINTVL)
1796                         err = -EINVAL;
1797                 else
1798                         tp->keepalive_intvl = val * HZ;
1799                 break;
1800         case TCP_KEEPCNT:
1801                 if (val < 1 || val > MAX_TCP_KEEPCNT)
1802                         err = -EINVAL;
1803                 else
1804                         tp->keepalive_probes = val;
1805                 break;
1806         case TCP_SYNCNT:
1807                 if (val < 1 || val > MAX_TCP_SYNCNT)
1808                         err = -EINVAL;
1809                 else
1810                         icsk->icsk_syn_retries = val;
1811                 break;
1812
1813         case TCP_LINGER2:
1814                 if (val < 0)
1815                         tp->linger2 = -1;
1816                 else if (val > sysctl_tcp_fin_timeout / HZ)
1817                         tp->linger2 = 0;
1818                 else
1819                         tp->linger2 = val * HZ;
1820                 break;
1821
1822         case TCP_DEFER_ACCEPT:
1823                 icsk->icsk_accept_queue.rskq_defer_accept = 0;
1824                 if (val > 0) {
1825                         /* Translate value in seconds to number of
1826                          * retransmits */
1827                         while (icsk->icsk_accept_queue.rskq_defer_accept < 32 &&
1828                                val > ((TCP_TIMEOUT_INIT / HZ) <<
1829                                        icsk->icsk_accept_queue.rskq_defer_accept))
1830                                 icsk->icsk_accept_queue.rskq_defer_accept++;
1831                         icsk->icsk_accept_queue.rskq_defer_accept++;
1832                 }
1833                 break;
1834
1835         case TCP_WINDOW_CLAMP:
1836                 if (!val) {
1837                         if (sk->sk_state != TCP_CLOSE) {
1838                                 err = -EINVAL;
1839                                 break;
1840                         }
1841                         tp->window_clamp = 0;
1842                 } else
1843                         tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
1844                                                 SOCK_MIN_RCVBUF / 2 : val;
1845                 break;
1846
1847         case TCP_QUICKACK:
1848                 if (!val) {
1849                         icsk->icsk_ack.pingpong = 1;
1850                 } else {
1851                         icsk->icsk_ack.pingpong = 0;
1852                         if ((1 << sk->sk_state) &
1853                             (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
1854                             inet_csk_ack_scheduled(sk)) {
1855                                 icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
1856                                 cleanup_rbuf(sk, 1);
1857                                 if (!(val & 1))
1858                                         icsk->icsk_ack.pingpong = 1;
1859                         }
1860                 }
1861                 break;
1862
1863         default:
1864                 err = -ENOPROTOOPT;
1865                 break;
1866         };
1867         release_sock(sk);
1868         return err;
1869 }
1870
1871 int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
1872                    int optlen)
1873 {
1874         struct inet_connection_sock *icsk = inet_csk(sk);
1875
1876         if (level != SOL_TCP)
1877                 return icsk->icsk_af_ops->setsockopt(sk, level, optname,
1878                                                      optval, optlen);
1879         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
1880 }
1881
1882 #ifdef CONFIG_COMPAT
1883 int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
1884                           char __user *optval, int optlen)
1885 {
1886         if (level != SOL_TCP)
1887                 return inet_csk_compat_setsockopt(sk, level, optname,
1888                                                   optval, optlen);
1889         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
1890 }
1891
1892 EXPORT_SYMBOL(compat_tcp_setsockopt);
1893 #endif
1894
1895 /* Return information about state of tcp endpoint in API format. */
1896 void tcp_get_info(struct sock *sk, struct tcp_info *info)
1897 {
1898         struct tcp_sock *tp = tcp_sk(sk);
1899         const struct inet_connection_sock *icsk = inet_csk(sk);
1900         u32 now = tcp_time_stamp;
1901
1902         memset(info, 0, sizeof(*info));
1903
1904         info->tcpi_state = sk->sk_state;
1905         info->tcpi_ca_state = icsk->icsk_ca_state;
1906         info->tcpi_retransmits = icsk->icsk_retransmits;
1907         info->tcpi_probes = icsk->icsk_probes_out;
1908         info->tcpi_backoff = icsk->icsk_backoff;
1909
1910         if (tp->rx_opt.tstamp_ok)
1911                 info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
1912         if (tp->rx_opt.sack_ok)
1913                 info->tcpi_options |= TCPI_OPT_SACK;
1914         if (tp->rx_opt.wscale_ok) {
1915                 info->tcpi_options |= TCPI_OPT_WSCALE;
1916                 info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
1917                 info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
1918         }
1919
1920         if (tp->ecn_flags&TCP_ECN_OK)
1921                 info->tcpi_options |= TCPI_OPT_ECN;
1922
1923         info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
1924         info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
1925         info->tcpi_snd_mss = tp->mss_cache;
1926         info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
1927
1928         info->tcpi_unacked = tp->packets_out;
1929         info->tcpi_sacked = tp->sacked_out;
1930         info->tcpi_lost = tp->lost_out;
1931         info->tcpi_retrans = tp->retrans_out;
1932         info->tcpi_fackets = tp->fackets_out;
1933
1934         info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
1935         info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
1936         info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
1937
1938         info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
1939         info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
1940         info->tcpi_rtt = jiffies_to_usecs(tp->srtt)>>3;
1941         info->tcpi_rttvar = jiffies_to_usecs(tp->mdev)>>2;
1942         info->tcpi_snd_ssthresh = tp->snd_ssthresh;
1943         info->tcpi_snd_cwnd = tp->snd_cwnd;
1944         info->tcpi_advmss = tp->advmss;
1945         info->tcpi_reordering = tp->reordering;
1946
1947         info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3;
1948         info->tcpi_rcv_space = tp->rcvq_space.space;
1949
1950         info->tcpi_total_retrans = tp->total_retrans;
1951 }
1952
1953 EXPORT_SYMBOL_GPL(tcp_get_info);
1954
1955 static int do_tcp_getsockopt(struct sock *sk, int level,
1956                 int optname, char __user *optval, int __user *optlen)
1957 {
1958         struct inet_connection_sock *icsk = inet_csk(sk);
1959         struct tcp_sock *tp = tcp_sk(sk);
1960         int val, len;
1961
1962         if (get_user(len, optlen))
1963                 return -EFAULT;
1964
1965         len = min_t(unsigned int, len, sizeof(int));
1966
1967         if (len < 0)
1968                 return -EINVAL;
1969
1970         switch (optname) {
1971         case TCP_MAXSEG:
1972                 val = tp->mss_cache;
1973                 if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
1974                         val = tp->rx_opt.user_mss;
1975                 break;
1976         case TCP_NODELAY:
1977                 val = !!(tp->nonagle&TCP_NAGLE_OFF);
1978                 break;
1979         case TCP_CORK:
1980                 val = !!(tp->nonagle&TCP_NAGLE_CORK);
1981                 break;
1982         case TCP_KEEPIDLE:
1983                 val = (tp->keepalive_time ? : sysctl_tcp_keepalive_time) / HZ;
1984                 break;
1985         case TCP_KEEPINTVL:
1986                 val = (tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl) / HZ;
1987                 break;
1988         case TCP_KEEPCNT:
1989                 val = tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1990                 break;
1991         case TCP_SYNCNT:
1992                 val = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
1993                 break;
1994         case TCP_LINGER2:
1995                 val = tp->linger2;
1996                 if (val >= 0)
1997                         val = (val ? : sysctl_tcp_fin_timeout) / HZ;
1998                 break;
1999         case TCP_DEFER_ACCEPT:
2000                 val = !icsk->icsk_accept_queue.rskq_defer_accept ? 0 :
2001                         ((TCP_TIMEOUT_INIT / HZ) << (icsk->icsk_accept_queue.rskq_defer_accept - 1));
2002                 break;
2003         case TCP_WINDOW_CLAMP:
2004                 val = tp->window_clamp;
2005                 break;
2006         case TCP_INFO: {
2007                 struct tcp_info info;
2008
2009                 if (get_user(len, optlen))
2010                         return -EFAULT;
2011
2012                 tcp_get_info(sk, &info);
2013
2014                 len = min_t(unsigned int, len, sizeof(info));
2015                 if (put_user(len, optlen))
2016                         return -EFAULT;
2017                 if (copy_to_user(optval, &info, len))
2018                         return -EFAULT;
2019                 return 0;
2020         }
2021         case TCP_QUICKACK:
2022                 val = !icsk->icsk_ack.pingpong;
2023                 break;
2024
2025         case TCP_CONGESTION:
2026                 if (get_user(len, optlen))
2027                         return -EFAULT;
2028                 len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
2029                 if (put_user(len, optlen))
2030                         return -EFAULT;
2031                 if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
2032                         return -EFAULT;
2033                 return 0;
2034         default:
2035                 return -ENOPROTOOPT;
2036         };
2037
2038         if (put_user(len, optlen))
2039                 return -EFAULT;
2040         if (copy_to_user(optval, &val, len))
2041                 return -EFAULT;
2042         return 0;
2043 }
2044
2045 int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
2046                    int __user *optlen)
2047 {
2048         struct inet_connection_sock *icsk = inet_csk(sk);
2049
2050         if (level != SOL_TCP)
2051                 return icsk->icsk_af_ops->getsockopt(sk, level, optname,
2052                                                      optval, optlen);
2053         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2054 }
2055
2056 #ifdef CONFIG_COMPAT
2057 int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
2058                           char __user *optval, int __user *optlen)
2059 {
2060         if (level != SOL_TCP)
2061                 return inet_csk_compat_getsockopt(sk, level, optname,
2062                                                   optval, optlen);
2063         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2064 }
2065
2066 EXPORT_SYMBOL(compat_tcp_getsockopt);
2067 #endif
2068
2069 extern void __skb_cb_too_small_for_tcp(int, int);
2070 extern struct tcp_congestion_ops tcp_reno;
2071
2072 static __initdata unsigned long thash_entries;
2073 static int __init set_thash_entries(char *str)
2074 {
2075         if (!str)
2076                 return 0;
2077         thash_entries = simple_strtoul(str, &str, 0);
2078         return 1;
2079 }
2080 __setup("thash_entries=", set_thash_entries);
2081
2082 void __init tcp_init(void)
2083 {
2084         struct sk_buff *skb = NULL;
2085         unsigned long limit;
2086         int order, i, max_share;
2087
2088         if (sizeof(struct tcp_skb_cb) > sizeof(skb->cb))
2089                 __skb_cb_too_small_for_tcp(sizeof(struct tcp_skb_cb),
2090                                            sizeof(skb->cb));
2091
2092         tcp_hashinfo.bind_bucket_cachep =
2093                 kmem_cache_create("tcp_bind_bucket",
2094                                   sizeof(struct inet_bind_bucket), 0,
2095                                   SLAB_HWCACHE_ALIGN, NULL, NULL);
2096         if (!tcp_hashinfo.bind_bucket_cachep)
2097                 panic("tcp_init: Cannot alloc tcp_bind_bucket cache.");
2098
2099         /* Size and allocate the main established and bind bucket
2100          * hash tables.
2101          *
2102          * The methodology is similar to that of the buffer cache.
2103          */
2104         tcp_hashinfo.ehash =
2105                 alloc_large_system_hash("TCP established",
2106                                         sizeof(struct inet_ehash_bucket),
2107                                         thash_entries,
2108                                         (num_physpages >= 128 * 1024) ?
2109                                         13 : 15,
2110                                         HASH_HIGHMEM,
2111                                         &tcp_hashinfo.ehash_size,
2112                                         NULL,
2113                                         0);
2114         tcp_hashinfo.ehash_size = (1 << tcp_hashinfo.ehash_size) >> 1;
2115         for (i = 0; i < (tcp_hashinfo.ehash_size << 1); i++) {
2116                 rwlock_init(&tcp_hashinfo.ehash[i].lock);
2117                 INIT_HLIST_HEAD(&tcp_hashinfo.ehash[i].chain);
2118         }
2119
2120         tcp_hashinfo.bhash =
2121                 alloc_large_system_hash("TCP bind",
2122                                         sizeof(struct inet_bind_hashbucket),
2123                                         tcp_hashinfo.ehash_size,
2124                                         (num_physpages >= 128 * 1024) ?
2125                                         13 : 15,
2126                                         HASH_HIGHMEM,
2127                                         &tcp_hashinfo.bhash_size,
2128                                         NULL,
2129                                         64 * 1024);
2130         tcp_hashinfo.bhash_size = 1 << tcp_hashinfo.bhash_size;
2131         for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
2132                 spin_lock_init(&tcp_hashinfo.bhash[i].lock);
2133                 INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
2134         }
2135
2136         /* Try to be a bit smarter and adjust defaults depending
2137          * on available memory.
2138          */
2139         for (order = 0; ((1 << order) << PAGE_SHIFT) <
2140                         (tcp_hashinfo.bhash_size * sizeof(struct inet_bind_hashbucket));
2141                         order++)
2142                 ;
2143         if (order >= 4) {
2144                 sysctl_local_port_range[0] = 32768;
2145                 sysctl_local_port_range[1] = 61000;
2146                 tcp_death_row.sysctl_max_tw_buckets = 180000;
2147                 sysctl_tcp_max_orphans = 4096 << (order - 4);
2148                 sysctl_max_syn_backlog = 1024;
2149         } else if (order < 3) {
2150                 sysctl_local_port_range[0] = 1024 * (3 - order);
2151                 tcp_death_row.sysctl_max_tw_buckets >>= (3 - order);
2152                 sysctl_tcp_max_orphans >>= (3 - order);
2153                 sysctl_max_syn_backlog = 128;
2154         }
2155
2156         sysctl_tcp_mem[0] =  768 << order;
2157         sysctl_tcp_mem[1] = 1024 << order;
2158         sysctl_tcp_mem[2] = 1536 << order;
2159
2160         limit = ((unsigned long)sysctl_tcp_mem[1]) << (PAGE_SHIFT - 7);
2161         max_share = min(4UL*1024*1024, limit);
2162
2163         sysctl_tcp_wmem[0] = SK_STREAM_MEM_QUANTUM;
2164         sysctl_tcp_wmem[1] = 16*1024;
2165         sysctl_tcp_wmem[2] = max(64*1024, max_share);
2166
2167         sysctl_tcp_rmem[0] = SK_STREAM_MEM_QUANTUM;
2168         sysctl_tcp_rmem[1] = 87380;
2169         sysctl_tcp_rmem[2] = max(87380, max_share);
2170
2171         printk(KERN_INFO "TCP: Hash tables configured "
2172                "(established %d bind %d)\n",
2173                tcp_hashinfo.ehash_size << 1, tcp_hashinfo.bhash_size);
2174
2175         tcp_register_congestion_control(&tcp_reno);
2176 }
2177
2178 EXPORT_SYMBOL(tcp_close);
2179 EXPORT_SYMBOL(tcp_disconnect);
2180 EXPORT_SYMBOL(tcp_getsockopt);
2181 EXPORT_SYMBOL(tcp_ioctl);
2182 EXPORT_SYMBOL(tcp_poll);
2183 EXPORT_SYMBOL(tcp_read_sock);
2184 EXPORT_SYMBOL(tcp_recvmsg);
2185 EXPORT_SYMBOL(tcp_sendmsg);
2186 EXPORT_SYMBOL(tcp_sendpage);
2187 EXPORT_SYMBOL(tcp_setsockopt);
2188 EXPORT_SYMBOL(tcp_shutdown);
2189 EXPORT_SYMBOL(tcp_statistics);