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