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