linux/net/ipv4/tcp.c
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   1/*
   2 * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3 *              operating system.  INET is implemented using the  BSD Socket
   4 *              interface as the means of communication with the user level.
   5 *
   6 *              Implementation of the Transmission Control Protocol(TCP).
   7 *
   8 * Authors:     Ross Biro
   9 *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  10 *              Mark Evans, <evansmp@uhura.aston.ac.uk>
  11 *              Corey Minyard <wf-rch!minyard@relay.EU.net>
  12 *              Florian La Roche, <flla@stud.uni-sb.de>
  13 *              Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
  14 *              Linus Torvalds, <torvalds@cs.helsinki.fi>
  15 *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  16 *              Matthew Dillon, <dillon@apollo.west.oic.com>
  17 *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
  18 *              Jorge Cwik, <jorge@laser.satlink.net>
  19 *
  20 * Fixes:
  21 *              Alan Cox        :       Numerous verify_area() calls
  22 *              Alan Cox        :       Set the ACK bit on a reset
  23 *              Alan Cox        :       Stopped it crashing if it closed while
  24 *                                      sk->inuse=1 and was trying to connect
  25 *                                      (tcp_err()).
  26 *              Alan Cox        :       All icmp error handling was broken
  27 *                                      pointers passed where wrong and the
  28 *                                      socket was looked up backwards. Nobody
  29 *                                      tested any icmp error code obviously.
  30 *              Alan Cox        :       tcp_err() now handled properly. It
  31 *                                      wakes people on errors. poll
  32 *                                      behaves and the icmp error race
  33 *                                      has gone by moving it into sock.c
  34 *              Alan Cox        :       tcp_send_reset() fixed to work for
  35 *                                      everything not just packets for
  36 *                                      unknown sockets.
  37 *              Alan Cox        :       tcp option processing.
  38 *              Alan Cox        :       Reset tweaked (still not 100%) [Had
  39 *                                      syn rule wrong]
  40 *              Herp Rosmanith  :       More reset fixes
  41 *              Alan Cox        :       No longer acks invalid rst frames.
  42 *                                      Acking any kind of RST is right out.
  43 *              Alan Cox        :       Sets an ignore me flag on an rst
  44 *                                      receive otherwise odd bits of prattle
  45 *                                      escape still
  46 *              Alan Cox        :       Fixed another acking RST frame bug.
  47 *                                      Should stop LAN workplace lockups.
  48 *              Alan Cox        :       Some tidyups using the new skb list
  49 *                                      facilities
  50 *              Alan Cox        :       sk->keepopen now seems to work
  51 *              Alan Cox        :       Pulls options out correctly on accepts
  52 *              Alan Cox        :       Fixed assorted sk->rqueue->next errors
  53 *              Alan Cox        :       PSH doesn't end a TCP read. Switched a
  54 *                                      bit to skb ops.
  55 *              Alan Cox        :       Tidied tcp_data to avoid a potential
  56 *                                      nasty.
  57 *              Alan Cox        :       Added some better commenting, as the
  58 *                                      tcp is hard to follow
  59 *              Alan Cox        :       Removed incorrect check for 20 * psh
  60 *      Michael O'Reilly        :       ack < copied bug fix.
  61 *      Johannes Stille         :       Misc tcp fixes (not all in yet).
  62 *              Alan Cox        :       FIN with no memory -> CRASH
  63 *              Alan Cox        :       Added socket option proto entries.
  64 *                                      Also added awareness of them to accept.
  65 *              Alan Cox        :       Added TCP options (SOL_TCP)
  66 *              Alan Cox        :       Switched wakeup calls to callbacks,
  67 *                                      so the kernel can layer network
  68 *                                      sockets.
  69 *              Alan Cox        :       Use ip_tos/ip_ttl settings.
  70 *              Alan Cox        :       Handle FIN (more) properly (we hope).
  71 *              Alan Cox        :       RST frames sent on unsynchronised
  72 *                                      state ack error.
  73 *              Alan Cox        :       Put in missing check for SYN bit.
  74 *              Alan Cox        :       Added tcp_select_window() aka NET2E
  75 *                                      window non shrink trick.
  76 *              Alan Cox        :       Added a couple of small NET2E timer
  77 *                                      fixes
  78 *              Charles Hedrick :       TCP fixes
  79 *              Toomas Tamm     :       TCP window fixes
  80 *              Alan Cox        :       Small URG fix to rlogin ^C ack fight
  81 *              Charles Hedrick :       Rewrote most of it to actually work
  82 *              Linus           :       Rewrote tcp_read() and URG handling
  83 *                                      completely
  84 *              Gerhard Koerting:       Fixed some missing timer handling
  85 *              Matthew Dillon  :       Reworked TCP machine states as per RFC
  86 *              Gerhard Koerting:       PC/TCP workarounds
  87 *              Adam Caldwell   :       Assorted timer/timing errors
  88 *              Matthew Dillon  :       Fixed another RST bug
  89 *              Alan Cox        :       Move to kernel side addressing changes.
  90 *              Alan Cox        :       Beginning work on TCP fastpathing
  91 *                                      (not yet usable)
  92 *              Arnt Gulbrandsen:       Turbocharged tcp_check() routine.
  93 *              Alan Cox        :       TCP fast path debugging
  94 *              Alan Cox        :       Window clamping
  95 *              Michael Riepe   :       Bug in tcp_check()
  96 *              Matt Dillon     :       More TCP improvements and RST bug fixes
  97 *              Matt Dillon     :       Yet more small nasties remove from the
  98 *                                      TCP code (Be very nice to this man if
  99 *                                      tcp finally works 100%) 8)
 100 *              Alan Cox        :       BSD accept semantics.
 101 *              Alan Cox        :       Reset on closedown bug.
 102 *      Peter De Schrijver      :       ENOTCONN check missing in tcp_sendto().
 103 *              Michael Pall    :       Handle poll() after URG properly in
 104 *                                      all cases.
 105 *              Michael Pall    :       Undo the last fix in tcp_read_urg()
 106 *                                      (multi URG PUSH broke rlogin).
 107 *              Michael Pall    :       Fix the multi URG PUSH problem in
 108 *                                      tcp_readable(), poll() after URG
 109 *                                      works now.
 110 *              Michael Pall    :       recv(...,MSG_OOB) never blocks in the
 111 *                                      BSD api.
 112 *              Alan Cox        :       Changed the semantics of sk->socket to
 113 *                                      fix a race and a signal problem with
 114 *                                      accept() and async I/O.
 115 *              Alan Cox        :       Relaxed the rules on tcp_sendto().
 116 *              Yury Shevchuk   :       Really fixed accept() blocking problem.
 117 *              Craig I. Hagan  :       Allow for BSD compatible TIME_WAIT for
 118 *                                      clients/servers which listen in on
 119 *                                      fixed ports.
 120 *              Alan Cox        :       Cleaned the above up and shrank it to
 121 *                                      a sensible code size.
 122 *              Alan Cox        :       Self connect lockup fix.
 123 *              Alan Cox        :       No connect to multicast.
 124 *              Ross Biro       :       Close unaccepted children on master
 125 *                                      socket close.
 126 *              Alan Cox        :       Reset tracing code.
 127 *              Alan Cox        :       Spurious resets on shutdown.
 128 *              Alan Cox        :       Giant 15 minute/60 second timer error
 129 *              Alan Cox        :       Small whoops in polling before an
 130 *                                      accept.
 131 *              Alan Cox        :       Kept the state trace facility since
 132 *                                      it's handy for debugging.
 133 *              Alan Cox        :       More reset handler fixes.
 134 *              Alan Cox        :       Started rewriting the code based on
 135 *                                      the RFC's for other useful protocol
 136 *                                      references see: Comer, KA9Q NOS, and
 137 *                                      for a reference on the difference
 138 *                                      between specifications and how BSD
 139 *                                      works see the 4.4lite source.
 140 *              A.N.Kuznetsov   :       Don't time wait on completion of tidy
 141 *                                      close.
 142 *              Linus Torvalds  :       Fin/Shutdown & copied_seq changes.
 143 *              Linus Torvalds  :       Fixed BSD port reuse to work first syn
 144 *              Alan Cox        :       Reimplemented timers as per the RFC
 145 *                                      and using multiple timers for sanity.
 146 *              Alan Cox        :       Small bug fixes, and a lot of new
 147 *                                      comments.
 148 *              Alan Cox        :       Fixed dual reader crash by locking
 149 *                                      the buffers (much like datagram.c)
 150 *              Alan Cox        :       Fixed stuck sockets in probe. A probe
 151 *                                      now gets fed up of retrying without
 152 *                                      (even a no space) answer.
 153 *              Alan Cox        :       Extracted closing code better
 154 *              Alan Cox        :       Fixed the closing state machine to
 155 *                                      resemble the RFC.
 156 *              Alan Cox        :       More 'per spec' fixes.
 157 *              Jorge Cwik      :       Even faster checksumming.
 158 *              Alan Cox        :       tcp_data() doesn't ack illegal PSH
 159 *                                      only frames. At least one pc tcp stack
 160 *                                      generates them.
 161 *              Alan Cox        :       Cache last socket.
 162 *              Alan Cox        :       Per route irtt.
 163 *              Matt Day        :       poll()->select() match BSD precisely on error
 164 *              Alan Cox        :       New buffers
 165 *              Marc Tamsky     :       Various sk->prot->retransmits and
 166 *                                      sk->retransmits misupdating fixed.
 167 *                                      Fixed tcp_write_timeout: stuck close,
 168 *                                      and TCP syn retries gets used now.
 169 *              Mark Yarvis     :       In tcp_read_wakeup(), don't send an
 170 *                                      ack if state is TCP_CLOSED.
 171 *              Alan Cox        :       Look up device on a retransmit - routes may
 172 *                                      change. Doesn't yet cope with MSS shrink right
 173 *                                      but it's a start!
 174 *              Marc Tamsky     :       Closing in closing fixes.
 175 *              Mike Shaver     :       RFC1122 verifications.
 176 *              Alan Cox        :       rcv_saddr errors.
 177 *              Alan Cox        :       Block double connect().
 178 *              Alan Cox        :       Small hooks for enSKIP.
 179 *              Alexey Kuznetsov:       Path MTU discovery.
 180 *              Alan Cox        :       Support soft errors.
 181 *              Alan Cox        :       Fix MTU discovery pathological case
 182 *                                      when the remote claims no mtu!
 183 *              Marc Tamsky     :       TCP_CLOSE fix.
 184 *              Colin (G3TNE)   :       Send a reset on syn ack replies in
 185 *                                      window but wrong (fixes NT lpd problems)
 186 *              Pedro Roque     :       Better TCP window handling, delayed ack.
 187 *              Joerg Reuter    :       No modification of locked buffers in
 188 *                                      tcp_do_retransmit()
 189 *              Eric Schenk     :       Changed receiver side silly window
 190 *                                      avoidance algorithm to BSD style
 191 *                                      algorithm. This doubles throughput
 192 *                                      against machines running Solaris,
 193 *                                      and seems to result in general
 194 *                                      improvement.
 195 *      Stefan Magdalinski      :       adjusted tcp_readable() to fix FIONREAD
 196 *      Willy Konynenberg       :       Transparent proxying support.
 197 *      Mike McLagan            :       Routing by source
 198 *              Keith Owens     :       Do proper merging with partial SKB's in
 199 *                                      tcp_do_sendmsg to avoid burstiness.
 200 *              Eric Schenk     :       Fix fast close down bug with
 201 *                                      shutdown() followed by close().
 202 *              Andi Kleen      :       Make poll agree with SIGIO
 203 *      Salvatore Sanfilippo    :       Support SO_LINGER with linger == 1 and
 204 *                                      lingertime == 0 (RFC 793 ABORT Call)
 205 *      Hirokazu Takahashi      :       Use copy_from_user() instead of
 206 *                                      csum_and_copy_from_user() if possible.
 207 *
 208 *              This program is free software; you can redistribute it and/or
 209 *              modify it under the terms of the GNU General Public License
 210 *              as published by the Free Software Foundation; either version
 211 *              2 of the License, or(at your option) any later version.
 212 *
 213 * Description of States:
 214 *
 215 *      TCP_SYN_SENT            sent a connection request, waiting for ack
 216 *
 217 *      TCP_SYN_RECV            received a connection request, sent ack,
 218 *                              waiting for final ack in three-way handshake.
 219 *
 220 *      TCP_ESTABLISHED         connection established
 221 *
 222 *      TCP_FIN_WAIT1           our side has shutdown, waiting to complete
 223 *                              transmission of remaining buffered data
 224 *
 225 *      TCP_FIN_WAIT2           all buffered data sent, waiting for remote
 226 *                              to shutdown
 227 *
 228 *      TCP_CLOSING             both sides have shutdown but we still have
 229 *                              data we have to finish sending
 230 *
 231 *      TCP_TIME_WAIT           timeout to catch resent junk before entering
 232 *                              closed, can only be entered from FIN_WAIT2
 233 *                              or CLOSING.  Required because the other end
 234 *                              may not have gotten our last ACK causing it
 235 *                              to retransmit the data packet (which we ignore)
 236 *
 237 *      TCP_CLOSE_WAIT          remote side has shutdown and is waiting for
 238 *                              us to finish writing our data and to shutdown
 239 *                              (we have to close() to move on to LAST_ACK)
 240 *
 241 *      TCP_LAST_ACK            out side has shutdown after remote has
 242 *                              shutdown.  There may still be data in our
 243 *                              buffer that we have to finish sending
 244 *
 245 *      TCP_CLOSE               socket is finished
 246 */
 247
 248#include <linux/kernel.h>
 249#include <linux/module.h>
 250#include <linux/types.h>
 251#include <linux/fcntl.h>
 252#include <linux/poll.h>
 253#include <linux/init.h>
 254#include <linux/fs.h>
 255#include <linux/skbuff.h>
 256#include <linux/scatterlist.h>
 257#include <linux/splice.h>
 258#include <linux/net.h>
 259#include <linux/socket.h>
 260#include <linux/random.h>
 261#include <linux/bootmem.h>
 262#include <linux/highmem.h>
 263#include <linux/swap.h>
 264#include <linux/cache.h>
 265#include <linux/err.h>
 266#include <linux/crypto.h>
 267#include <linux/time.h>
 268#include <linux/slab.h>
 269
 270#include <net/icmp.h>
 271#include <net/tcp.h>
 272#include <net/xfrm.h>
 273#include <net/ip.h>
 274#include <net/netdma.h>
 275#include <net/sock.h>
 276
 277#include <asm/uaccess.h>
 278#include <asm/ioctls.h>
 279
 280int sysctl_tcp_fin_timeout __read_mostly = TCP_FIN_TIMEOUT;
 281
 282struct percpu_counter tcp_orphan_count;
 283EXPORT_SYMBOL_GPL(tcp_orphan_count);
 284
 285int sysctl_tcp_mem[3] __read_mostly;
 286int sysctl_tcp_wmem[3] __read_mostly;
 287int sysctl_tcp_rmem[3] __read_mostly;
 288
 289EXPORT_SYMBOL(sysctl_tcp_mem);
 290EXPORT_SYMBOL(sysctl_tcp_rmem);
 291EXPORT_SYMBOL(sysctl_tcp_wmem);
 292
 293atomic_t tcp_memory_allocated;  /* Current allocated memory. */
 294EXPORT_SYMBOL(tcp_memory_allocated);
 295
 296/*
 297 * Current number of TCP sockets.
 298 */
 299struct percpu_counter tcp_sockets_allocated;
 300EXPORT_SYMBOL(tcp_sockets_allocated);
 301
 302/*
 303 * TCP splice context
 304 */
 305struct tcp_splice_state {
 306        struct pipe_inode_info *pipe;
 307        size_t len;
 308        unsigned int flags;
 309};
 310
 311/*
 312 * Pressure flag: try to collapse.
 313 * Technical note: it is used by multiple contexts non atomically.
 314 * All the __sk_mem_schedule() is of this nature: accounting
 315 * is strict, actions are advisory and have some latency.
 316 */
 317int tcp_memory_pressure __read_mostly;
 318
 319EXPORT_SYMBOL(tcp_memory_pressure);
 320
 321void tcp_enter_memory_pressure(struct sock *sk)
 322{
 323        if (!tcp_memory_pressure) {
 324                NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMEMORYPRESSURES);
 325                tcp_memory_pressure = 1;
 326        }
 327}
 328
 329EXPORT_SYMBOL(tcp_enter_memory_pressure);
 330
 331/* Convert seconds to retransmits based on initial and max timeout */
 332static u8 secs_to_retrans(int seconds, int timeout, int rto_max)
 333{
 334        u8 res = 0;
 335
 336        if (seconds > 0) {
 337                int period = timeout;
 338
 339                res = 1;
 340                while (seconds > period && res < 255) {
 341                        res++;
 342                        timeout <<= 1;
 343                        if (timeout > rto_max)
 344                                timeout = rto_max;
 345                        period += timeout;
 346                }
 347        }
 348        return res;
 349}
 350
 351/* Convert retransmits to seconds based on initial and max timeout */
 352static int retrans_to_secs(u8 retrans, int timeout, int rto_max)
 353{
 354        int period = 0;
 355
 356        if (retrans > 0) {
 357                period = timeout;
 358                while (--retrans) {
 359                        timeout <<= 1;
 360                        if (timeout > rto_max)
 361                                timeout = rto_max;
 362                        period += timeout;
 363                }
 364        }
 365        return period;
 366}
 367
 368/*
 369 *      Wait for a TCP event.
 370 *
 371 *      Note that we don't need to lock the socket, as the upper poll layers
 372 *      take care of normal races (between the test and the event) and we don't
 373 *      go look at any of the socket buffers directly.
 374 */
 375unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
 376{
 377        unsigned int mask;
 378        struct sock *sk = sock->sk;
 379        struct tcp_sock *tp = tcp_sk(sk);
 380
 381        sock_poll_wait(file, sk_sleep(sk), wait);
 382        if (sk->sk_state == TCP_LISTEN)
 383                return inet_csk_listen_poll(sk);
 384
 385        /* Socket is not locked. We are protected from async events
 386         * by poll logic and correct handling of state changes
 387         * made by other threads is impossible in any case.
 388         */
 389
 390        mask = 0;
 391        if (sk->sk_err)
 392                mask = POLLERR;
 393
 394        /*
 395         * POLLHUP is certainly not done right. But poll() doesn't
 396         * have a notion of HUP in just one direction, and for a
 397         * socket the read side is more interesting.
 398         *
 399         * Some poll() documentation says that POLLHUP is incompatible
 400         * with the POLLOUT/POLLWR flags, so somebody should check this
 401         * all. But careful, it tends to be safer to return too many
 402         * bits than too few, and you can easily break real applications
 403         * if you don't tell them that something has hung up!
 404         *
 405         * Check-me.
 406         *
 407         * Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and
 408         * our fs/select.c). It means that after we received EOF,
 409         * poll always returns immediately, making impossible poll() on write()
 410         * in state CLOSE_WAIT. One solution is evident --- to set POLLHUP
 411         * if and only if shutdown has been made in both directions.
 412         * Actually, it is interesting to look how Solaris and DUX
 413         * solve this dilemma. I would prefer, if POLLHUP were maskable,
 414         * then we could set it on SND_SHUTDOWN. BTW examples given
 415         * in Stevens' books assume exactly this behaviour, it explains
 416         * why POLLHUP is incompatible with POLLOUT.    --ANK
 417         *
 418         * NOTE. Check for TCP_CLOSE is added. The goal is to prevent
 419         * blocking on fresh not-connected or disconnected socket. --ANK
 420         */
 421        if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == TCP_CLOSE)
 422                mask |= POLLHUP;
 423        if (sk->sk_shutdown & RCV_SHUTDOWN)
 424                mask |= POLLIN | POLLRDNORM | POLLRDHUP;
 425
 426        /* Connected? */
 427        if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV)) {
 428                int target = sock_rcvlowat(sk, 0, INT_MAX);
 429
 430                if (tp->urg_seq == tp->copied_seq &&
 431                    !sock_flag(sk, SOCK_URGINLINE) &&
 432                    tp->urg_data)
 433                        target++;
 434
 435                /* Potential race condition. If read of tp below will
 436                 * escape above sk->sk_state, we can be illegally awaken
 437                 * in SYN_* states. */
 438                if (tp->rcv_nxt - tp->copied_seq >= target)
 439                        mask |= POLLIN | POLLRDNORM;
 440
 441                if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
 442                        if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
 443                                mask |= POLLOUT | POLLWRNORM;
 444                        } else {  /* send SIGIO later */
 445                                set_bit(SOCK_ASYNC_NOSPACE,
 446                                        &sk->sk_socket->flags);
 447                                set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 448
 449                                /* Race breaker. If space is freed after
 450                                 * wspace test but before the flags are set,
 451                                 * IO signal will be lost.
 452                                 */
 453                                if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk))
 454                                        mask |= POLLOUT | POLLWRNORM;
 455                        }
 456                }
 457
 458                if (tp->urg_data & TCP_URG_VALID)
 459                        mask |= POLLPRI;
 460        }
 461        return mask;
 462}
 463
 464int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
 465{
 466        struct tcp_sock *tp = tcp_sk(sk);
 467        int answ;
 468
 469        switch (cmd) {
 470        case SIOCINQ:
 471                if (sk->sk_state == TCP_LISTEN)
 472                        return -EINVAL;
 473
 474                lock_sock(sk);
 475                if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
 476                        answ = 0;
 477                else if (sock_flag(sk, SOCK_URGINLINE) ||
 478                         !tp->urg_data ||
 479                         before(tp->urg_seq, tp->copied_seq) ||
 480                         !before(tp->urg_seq, tp->rcv_nxt)) {
 481                        struct sk_buff *skb;
 482
 483                        answ = tp->rcv_nxt - tp->copied_seq;
 484
 485                        /* Subtract 1, if FIN is in queue. */
 486                        skb = skb_peek_tail(&sk->sk_receive_queue);
 487                        if (answ && skb)
 488                                answ -= tcp_hdr(skb)->fin;
 489                } else
 490                        answ = tp->urg_seq - tp->copied_seq;
 491                release_sock(sk);
 492                break;
 493        case SIOCATMARK:
 494                answ = tp->urg_data && tp->urg_seq == tp->copied_seq;
 495                break;
 496        case SIOCOUTQ:
 497                if (sk->sk_state == TCP_LISTEN)
 498                        return -EINVAL;
 499
 500                if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
 501                        answ = 0;
 502                else
 503                        answ = tp->write_seq - tp->snd_una;
 504                break;
 505        default:
 506                return -ENOIOCTLCMD;
 507        }
 508
 509        return put_user(answ, (int __user *)arg);
 510}
 511
 512static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
 513{
 514        TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH;
 515        tp->pushed_seq = tp->write_seq;
 516}
 517
 518static inline int forced_push(struct tcp_sock *tp)
 519{
 520        return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
 521}
 522
 523static inline void skb_entail(struct sock *sk, struct sk_buff *skb)
 524{
 525        struct tcp_sock *tp = tcp_sk(sk);
 526        struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
 527
 528        skb->csum    = 0;
 529        tcb->seq     = tcb->end_seq = tp->write_seq;
 530        tcb->flags   = TCPCB_FLAG_ACK;
 531        tcb->sacked  = 0;
 532        skb_header_release(skb);
 533        tcp_add_write_queue_tail(sk, skb);
 534        sk->sk_wmem_queued += skb->truesize;
 535        sk_mem_charge(sk, skb->truesize);
 536        if (tp->nonagle & TCP_NAGLE_PUSH)
 537                tp->nonagle &= ~TCP_NAGLE_PUSH;
 538}
 539
 540static inline void tcp_mark_urg(struct tcp_sock *tp, int flags)
 541{
 542        if (flags & MSG_OOB)
 543                tp->snd_up = tp->write_seq;
 544}
 545
 546static inline void tcp_push(struct sock *sk, int flags, int mss_now,
 547                            int nonagle)
 548{
 549        if (tcp_send_head(sk)) {
 550                struct tcp_sock *tp = tcp_sk(sk);
 551
 552                if (!(flags & MSG_MORE) || forced_push(tp))
 553                        tcp_mark_push(tp, tcp_write_queue_tail(sk));
 554
 555                tcp_mark_urg(tp, flags);
 556                __tcp_push_pending_frames(sk, mss_now,
 557                                          (flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle);
 558        }
 559}
 560
 561static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
 562                                unsigned int offset, size_t len)
 563{
 564        struct tcp_splice_state *tss = rd_desc->arg.data;
 565        int ret;
 566
 567        ret = skb_splice_bits(skb, offset, tss->pipe, min(rd_desc->count, len),
 568                              tss->flags);
 569        if (ret > 0)
 570                rd_desc->count -= ret;
 571        return ret;
 572}
 573
 574static int __tcp_splice_read(struct sock *sk, struct tcp_splice_state *tss)
 575{
 576        /* Store TCP splice context information in read_descriptor_t. */
 577        read_descriptor_t rd_desc = {
 578                .arg.data = tss,
 579                .count    = tss->len,
 580        };
 581
 582        return tcp_read_sock(sk, &rd_desc, tcp_splice_data_recv);
 583}
 584
 585/**
 586 *  tcp_splice_read - splice data from TCP socket to a pipe
 587 * @sock:       socket to splice from
 588 * @ppos:       position (not valid)
 589 * @pipe:       pipe to splice to
 590 * @len:        number of bytes to splice
 591 * @flags:      splice modifier flags
 592 *
 593 * Description:
 594 *    Will read pages from given socket and fill them into a pipe.
 595 *
 596 **/
 597ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
 598                        struct pipe_inode_info *pipe, size_t len,
 599                        unsigned int flags)
 600{
 601        struct sock *sk = sock->sk;
 602        struct tcp_splice_state tss = {
 603                .pipe = pipe,
 604                .len = len,
 605                .flags = flags,
 606        };
 607        long timeo;
 608        ssize_t spliced;
 609        int ret;
 610
 611        sock_rps_record_flow(sk);
 612        /*
 613         * We can't seek on a socket input
 614         */
 615        if (unlikely(*ppos))
 616                return -ESPIPE;
 617
 618        ret = spliced = 0;
 619
 620        lock_sock(sk);
 621
 622        timeo = sock_rcvtimeo(sk, sock->file->f_flags & O_NONBLOCK);
 623        while (tss.len) {
 624                ret = __tcp_splice_read(sk, &tss);
 625                if (ret < 0)
 626                        break;
 627                else if (!ret) {
 628                        if (spliced)
 629                                break;
 630                        if (sock_flag(sk, SOCK_DONE))
 631                                break;
 632                        if (sk->sk_err) {
 633                                ret = sock_error(sk);
 634                                break;
 635                        }
 636                        if (sk->sk_shutdown & RCV_SHUTDOWN)
 637                                break;
 638                        if (sk->sk_state == TCP_CLOSE) {
 639                                /*
 640                                 * This occurs when user tries to read
 641                                 * from never connected socket.
 642                                 */
 643                                if (!sock_flag(sk, SOCK_DONE))
 644                                        ret = -ENOTCONN;
 645                                break;
 646                        }
 647                        if (!timeo) {
 648                                ret = -EAGAIN;
 649                                break;
 650                        }
 651                        sk_wait_data(sk, &timeo);
 652                        if (signal_pending(current)) {
 653                                ret = sock_intr_errno(timeo);
 654                                break;
 655                        }
 656                        continue;
 657                }
 658                tss.len -= ret;
 659                spliced += ret;
 660
 661                if (!timeo)
 662                        break;
 663                release_sock(sk);
 664                lock_sock(sk);
 665
 666                if (sk->sk_err || sk->sk_state == TCP_CLOSE ||
 667                    (sk->sk_shutdown & RCV_SHUTDOWN) ||
 668                    signal_pending(current))
 669                        break;
 670        }
 671
 672        release_sock(sk);
 673
 674        if (spliced)
 675                return spliced;
 676
 677        return ret;
 678}
 679
 680struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp)
 681{
 682        struct sk_buff *skb;
 683
 684        /* The TCP header must be at least 32-bit aligned.  */
 685        size = ALIGN(size, 4);
 686
 687        skb = alloc_skb_fclone(size + sk->sk_prot->max_header, gfp);
 688        if (skb) {
 689                if (sk_wmem_schedule(sk, skb->truesize)) {
 690                        /*
 691                         * Make sure that we have exactly size bytes
 692                         * available to the caller, no more, no less.
 693                         */
 694                        skb_reserve(skb, skb_tailroom(skb) - size);
 695                        return skb;
 696                }
 697                __kfree_skb(skb);
 698        } else {
 699                sk->sk_prot->enter_memory_pressure(sk);
 700                sk_stream_moderate_sndbuf(sk);
 701        }
 702        return NULL;
 703}
 704
 705static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,
 706                                       int large_allowed)
 707{
 708        struct tcp_sock *tp = tcp_sk(sk);
 709        u32 xmit_size_goal, old_size_goal;
 710
 711        xmit_size_goal = mss_now;
 712
 713        if (large_allowed && sk_can_gso(sk)) {
 714                xmit_size_goal = ((sk->sk_gso_max_size - 1) -
 715                                  inet_csk(sk)->icsk_af_ops->net_header_len -
 716                                  inet_csk(sk)->icsk_ext_hdr_len -
 717                                  tp->tcp_header_len);
 718
 719                xmit_size_goal = tcp_bound_to_half_wnd(tp, xmit_size_goal);
 720
 721                /* We try hard to avoid divides here */
 722                old_size_goal = tp->xmit_size_goal_segs * mss_now;
 723
 724                if (likely(old_size_goal <= xmit_size_goal &&
 725                           old_size_goal + mss_now > xmit_size_goal)) {
 726                        xmit_size_goal = old_size_goal;
 727                } else {
 728                        tp->xmit_size_goal_segs = xmit_size_goal / mss_now;
 729                        xmit_size_goal = tp->xmit_size_goal_segs * mss_now;
 730                }
 731        }
 732
 733        return max(xmit_size_goal, mss_now);
 734}
 735
 736static int tcp_send_mss(struct sock *sk, int *size_goal, int flags)
 737{
 738        int mss_now;
 739
 740        mss_now = tcp_current_mss(sk);
 741        *size_goal = tcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));
 742
 743        return mss_now;
 744}
 745
 746static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset,
 747                         size_t psize, int flags)
 748{
 749        struct tcp_sock *tp = tcp_sk(sk);
 750        int mss_now, size_goal;
 751        int err;
 752        ssize_t copied;
 753        long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 754
 755        /* Wait for a connection to finish. */
 756        if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
 757                if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
 758                        goto out_err;
 759
 760        clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 761
 762        mss_now = tcp_send_mss(sk, &size_goal, flags);
 763        copied = 0;
 764
 765        err = -EPIPE;
 766        if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 767                goto out_err;
 768
 769        while (psize > 0) {
 770                struct sk_buff *skb = tcp_write_queue_tail(sk);
 771                struct page *page = pages[poffset / PAGE_SIZE];
 772                int copy, i, can_coalesce;
 773                int offset = poffset % PAGE_SIZE;
 774                int size = min_t(size_t, psize, PAGE_SIZE - offset);
 775
 776                if (!tcp_send_head(sk) || (copy = size_goal - skb->len) <= 0) {
 777new_segment:
 778                        if (!sk_stream_memory_free(sk))
 779                                goto wait_for_sndbuf;
 780
 781                        skb = sk_stream_alloc_skb(sk, 0, sk->sk_allocation);
 782                        if (!skb)
 783                                goto wait_for_memory;
 784
 785                        skb_entail(sk, skb);
 786                        copy = size_goal;
 787                }
 788
 789                if (copy > size)
 790                        copy = size;
 791
 792                i = skb_shinfo(skb)->nr_frags;
 793                can_coalesce = skb_can_coalesce(skb, i, page, offset);
 794                if (!can_coalesce && i >= MAX_SKB_FRAGS) {
 795                        tcp_mark_push(tp, skb);
 796                        goto new_segment;
 797                }
 798                if (!sk_wmem_schedule(sk, copy))
 799                        goto wait_for_memory;
 800
 801                if (can_coalesce) {
 802                        skb_shinfo(skb)->frags[i - 1].size += copy;
 803                } else {
 804                        get_page(page);
 805                        skb_fill_page_desc(skb, i, page, offset, copy);
 806                }
 807
 808                skb->len += copy;
 809                skb->data_len += copy;
 810                skb->truesize += copy;
 811                sk->sk_wmem_queued += copy;
 812                sk_mem_charge(sk, copy);
 813                skb->ip_summed = CHECKSUM_PARTIAL;
 814                tp->write_seq += copy;
 815                TCP_SKB_CB(skb)->end_seq += copy;
 816                skb_shinfo(skb)->gso_segs = 0;
 817
 818                if (!copied)
 819                        TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
 820
 821                copied += copy;
 822                poffset += copy;
 823                if (!(psize -= copy))
 824                        goto out;
 825
 826                if (skb->len < size_goal || (flags & MSG_OOB))
 827                        continue;
 828
 829                if (forced_push(tp)) {
 830                        tcp_mark_push(tp, skb);
 831                        __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
 832                } else if (skb == tcp_send_head(sk))
 833                        tcp_push_one(sk, mss_now);
 834                continue;
 835
 836wait_for_sndbuf:
 837                set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 838wait_for_memory:
 839                if (copied)
 840                        tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
 841
 842                if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
 843                        goto do_error;
 844
 845                mss_now = tcp_send_mss(sk, &size_goal, flags);
 846        }
 847
 848out:
 849        if (copied)
 850                tcp_push(sk, flags, mss_now, tp->nonagle);
 851        return copied;
 852
 853do_error:
 854        if (copied)
 855                goto out;
 856out_err:
 857        return sk_stream_error(sk, flags, err);
 858}
 859
 860ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset,
 861                     size_t size, int flags)
 862{
 863        ssize_t res;
 864        struct sock *sk = sock->sk;
 865
 866        if (!(sk->sk_route_caps & NETIF_F_SG) ||
 867            !(sk->sk_route_caps & NETIF_F_ALL_CSUM))
 868                return sock_no_sendpage(sock, page, offset, size, flags);
 869
 870        lock_sock(sk);
 871        TCP_CHECK_TIMER(sk);
 872        res = do_tcp_sendpages(sk, &page, offset, size, flags);
 873        TCP_CHECK_TIMER(sk);
 874        release_sock(sk);
 875        return res;
 876}
 877
 878#define TCP_PAGE(sk)    (sk->sk_sndmsg_page)
 879#define TCP_OFF(sk)     (sk->sk_sndmsg_off)
 880
 881static inline int select_size(struct sock *sk, int sg)
 882{
 883        struct tcp_sock *tp = tcp_sk(sk);
 884        int tmp = tp->mss_cache;
 885
 886        if (sg) {
 887                if (sk_can_gso(sk))
 888                        tmp = 0;
 889                else {
 890                        int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
 891
 892                        if (tmp >= pgbreak &&
 893                            tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
 894                                tmp = pgbreak;
 895                }
 896        }
 897
 898        return tmp;
 899}
 900
 901int tcp_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
 902                size_t size)
 903{
 904        struct sock *sk = sock->sk;
 905        struct iovec *iov;
 906        struct tcp_sock *tp = tcp_sk(sk);
 907        struct sk_buff *skb;
 908        int iovlen, flags;
 909        int mss_now, size_goal;
 910        int sg, err, copied;
 911        long timeo;
 912
 913        lock_sock(sk);
 914        TCP_CHECK_TIMER(sk);
 915
 916        flags = msg->msg_flags;
 917        timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 918
 919        /* Wait for a connection to finish. */
 920        if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
 921                if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
 922                        goto out_err;
 923
 924        /* This should be in poll */
 925        clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 926
 927        mss_now = tcp_send_mss(sk, &size_goal, flags);
 928
 929        /* Ok commence sending. */
 930        iovlen = msg->msg_iovlen;
 931        iov = msg->msg_iov;
 932        copied = 0;
 933
 934        err = -EPIPE;
 935        if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 936                goto out_err;
 937
 938        sg = sk->sk_route_caps & NETIF_F_SG;
 939
 940        while (--iovlen >= 0) {
 941                int seglen = iov->iov_len;
 942                unsigned char __user *from = iov->iov_base;
 943
 944                iov++;
 945
 946                while (seglen > 0) {
 947                        int copy = 0;
 948                        int max = size_goal;
 949
 950                        skb = tcp_write_queue_tail(sk);
 951                        if (tcp_send_head(sk)) {
 952                                if (skb->ip_summed == CHECKSUM_NONE)
 953                                        max = mss_now;
 954                                copy = max - skb->len;
 955                        }
 956
 957                        if (copy <= 0) {
 958new_segment:
 959                                /* Allocate new segment. If the interface is SG,
 960                                 * allocate skb fitting to single page.
 961                                 */
 962                                if (!sk_stream_memory_free(sk))
 963                                        goto wait_for_sndbuf;
 964
 965                                skb = sk_stream_alloc_skb(sk,
 966                                                          select_size(sk, sg),
 967                                                          sk->sk_allocation);
 968                                if (!skb)
 969                                        goto wait_for_memory;
 970
 971                                /*
 972                                 * Check whether we can use HW checksum.
 973                                 */
 974                                if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
 975                                        skb->ip_summed = CHECKSUM_PARTIAL;
 976
 977                                skb_entail(sk, skb);
 978                                copy = size_goal;
 979                                max = size_goal;
 980                        }
 981
 982                        /* Try to append data to the end of skb. */
 983                        if (copy > seglen)
 984                                copy = seglen;
 985
 986                        /* Where to copy to? */
 987                        if (skb_tailroom(skb) > 0) {
 988                                /* We have some space in skb head. Superb! */
 989                                if (copy > skb_tailroom(skb))
 990                                        copy = skb_tailroom(skb);
 991                                if ((err = skb_add_data(skb, from, copy)) != 0)
 992                                        goto do_fault;
 993                        } else {
 994                                int merge = 0;
 995                                int i = skb_shinfo(skb)->nr_frags;
 996                                struct page *page = TCP_PAGE(sk);
 997                                int off = TCP_OFF(sk);
 998
 999                                if (skb_can_coalesce(skb, i, page, off) &&
1000                                    off != PAGE_SIZE) {
1001                                        /* We can extend the last page
1002                                         * fragment. */
1003                                        merge = 1;
1004                                } else if (i == MAX_SKB_FRAGS || !sg) {
1005                                        /* Need to add new fragment and cannot
1006                                         * do this because interface is non-SG,
1007                                         * or because all the page slots are
1008                                         * busy. */
1009                                        tcp_mark_push(tp, skb);
1010                                        goto new_segment;
1011                                } else if (page) {
1012                                        if (off == PAGE_SIZE) {
1013                                                put_page(page);
1014                                                TCP_PAGE(sk) = page = NULL;
1015                                                off = 0;
1016                                        }
1017                                } else
1018                                        off = 0;
1019
1020                                if (copy > PAGE_SIZE - off)
1021                                        copy = PAGE_SIZE - off;
1022
1023                                if (!sk_wmem_schedule(sk, copy))
1024                                        goto wait_for_memory;
1025
1026                                if (!page) {
1027                                        /* Allocate new cache page. */
1028                                        if (!(page = sk_stream_alloc_page(sk)))
1029                                                goto wait_for_memory;
1030                                }
1031
1032                                /* Time to copy data. We are close to
1033                                 * the end! */
1034                                err = skb_copy_to_page(sk, from, skb, page,
1035                                                       off, copy);
1036                                if (err) {
1037                                        /* If this page was new, give it to the
1038                                         * socket so it does not get leaked.
1039                                         */
1040                                        if (!TCP_PAGE(sk)) {
1041                                                TCP_PAGE(sk) = page;
1042                                                TCP_OFF(sk) = 0;
1043                                        }
1044                                        goto do_error;
1045                                }
1046
1047                                /* Update the skb. */
1048                                if (merge) {
1049                                        skb_shinfo(skb)->frags[i - 1].size +=
1050                                                                        copy;
1051                                } else {
1052                                        skb_fill_page_desc(skb, i, page, off, copy);
1053                                        if (TCP_PAGE(sk)) {
1054                                                get_page(page);
1055                                        } else if (off + copy < PAGE_SIZE) {
1056                                                get_page(page);
1057                                                TCP_PAGE(sk) = page;
1058                                        }
1059                                }
1060
1061                                TCP_OFF(sk) = off + copy;
1062                        }
1063
1064                        if (!copied)
1065                                TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
1066
1067                        tp->write_seq += copy;
1068                        TCP_SKB_CB(skb)->end_seq += copy;
1069                        skb_shinfo(skb)->gso_segs = 0;
1070
1071                        from += copy;
1072                        copied += copy;
1073                        if ((seglen -= copy) == 0 && iovlen == 0)
1074                                goto out;
1075
1076                        if (skb->len < max || (flags & MSG_OOB))
1077                                continue;
1078
1079                        if (forced_push(tp)) {
1080                                tcp_mark_push(tp, skb);
1081                                __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
1082                        } else if (skb == tcp_send_head(sk))
1083                                tcp_push_one(sk, mss_now);
1084                        continue;
1085
1086wait_for_sndbuf:
1087                        set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
1088wait_for_memory:
1089                        if (copied)
1090                                tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
1091
1092                        if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
1093                                goto do_error;
1094
1095                        mss_now = tcp_send_mss(sk, &size_goal, flags);
1096                }
1097        }
1098
1099out:
1100        if (copied)
1101                tcp_push(sk, flags, mss_now, tp->nonagle);
1102        TCP_CHECK_TIMER(sk);
1103        release_sock(sk);
1104        return copied;
1105
1106do_fault:
1107        if (!skb->len) {
1108                tcp_unlink_write_queue(skb, sk);
1109                /* It is the one place in all of TCP, except connection
1110                 * reset, where we can be unlinking the send_head.
1111                 */
1112                tcp_check_send_head(sk, skb);
1113                sk_wmem_free_skb(sk, skb);
1114        }
1115
1116do_error:
1117        if (copied)
1118                goto out;
1119out_err:
1120        err = sk_stream_error(sk, flags, err);
1121        TCP_CHECK_TIMER(sk);
1122        release_sock(sk);
1123        return err;
1124}
1125
1126/*
1127 *      Handle reading urgent data. BSD has very simple semantics for
1128 *      this, no blocking and very strange errors 8)
1129 */
1130
1131static int tcp_recv_urg(struct sock *sk, struct msghdr *msg, int len, int flags)
1132{
1133        struct tcp_sock *tp = tcp_sk(sk);
1134
1135        /* No URG data to read. */
1136        if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
1137            tp->urg_data == TCP_URG_READ)
1138                return -EINVAL; /* Yes this is right ! */
1139
1140        if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
1141                return -ENOTCONN;
1142
1143        if (tp->urg_data & TCP_URG_VALID) {
1144                int err = 0;
1145                char c = tp->urg_data;
1146
1147                if (!(flags & MSG_PEEK))
1148                        tp->urg_data = TCP_URG_READ;
1149
1150                /* Read urgent data. */
1151                msg->msg_flags |= MSG_OOB;
1152
1153                if (len > 0) {
1154                        if (!(flags & MSG_TRUNC))
1155                                err = memcpy_toiovec(msg->msg_iov, &c, 1);
1156                        len = 1;
1157                } else
1158                        msg->msg_flags |= MSG_TRUNC;
1159
1160                return err ? -EFAULT : len;
1161        }
1162
1163        if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
1164                return 0;
1165
1166        /* Fixed the recv(..., MSG_OOB) behaviour.  BSD docs and
1167         * the available implementations agree in this case:
1168         * this call should never block, independent of the
1169         * blocking state of the socket.
1170         * Mike <pall@rz.uni-karlsruhe.de>
1171         */
1172        return -EAGAIN;
1173}
1174
1175/* Clean up the receive buffer for full frames taken by the user,
1176 * then send an ACK if necessary.  COPIED is the number of bytes
1177 * tcp_recvmsg has given to the user so far, it speeds up the
1178 * calculation of whether or not we must ACK for the sake of
1179 * a window update.
1180 */
1181void tcp_cleanup_rbuf(struct sock *sk, int copied)
1182{
1183        struct tcp_sock *tp = tcp_sk(sk);
1184        int time_to_ack = 0;
1185
1186#if TCP_DEBUG
1187        struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
1188
1189        WARN(skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq),
1190             KERN_INFO "cleanup rbuf bug: copied %X seq %X rcvnxt %X\n",
1191             tp->copied_seq, TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt);
1192#endif
1193
1194        if (inet_csk_ack_scheduled(sk)) {
1195                const struct inet_connection_sock *icsk = inet_csk(sk);
1196                   /* Delayed ACKs frequently hit locked sockets during bulk
1197                    * receive. */
1198                if (icsk->icsk_ack.blocked ||
1199                    /* Once-per-two-segments ACK was not sent by tcp_input.c */
1200                    tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
1201                    /*
1202                     * If this read emptied read buffer, we send ACK, if
1203                     * connection is not bidirectional, user drained
1204                     * receive buffer and there was a small segment
1205                     * in queue.
1206                     */
1207                    (copied > 0 &&
1208                     ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) ||
1209                      ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
1210                       !icsk->icsk_ack.pingpong)) &&
1211                      !atomic_read(&sk->sk_rmem_alloc)))
1212                        time_to_ack = 1;
1213        }
1214
1215        /* We send an ACK if we can now advertise a non-zero window
1216         * which has been raised "significantly".
1217         *
1218         * Even if window raised up to infinity, do not send window open ACK
1219         * in states, where we will not receive more. It is useless.
1220         */
1221        if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
1222                __u32 rcv_window_now = tcp_receive_window(tp);
1223
1224                /* Optimize, __tcp_select_window() is not cheap. */
1225                if (2*rcv_window_now <= tp->window_clamp) {
1226                        __u32 new_window = __tcp_select_window(sk);
1227
1228                        /* Send ACK now, if this read freed lots of space
1229                         * in our buffer. Certainly, new_window is new window.
1230                         * We can advertise it now, if it is not less than current one.
1231                         * "Lots" means "at least twice" here.
1232                         */
1233                        if (new_window && new_window >= 2 * rcv_window_now)
1234                                time_to_ack = 1;
1235                }
1236        }
1237        if (time_to_ack)
1238                tcp_send_ack(sk);
1239}
1240
1241static void tcp_prequeue_process(struct sock *sk)
1242{
1243        struct sk_buff *skb;
1244        struct tcp_sock *tp = tcp_sk(sk);
1245
1246        NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPPREQUEUED);
1247
1248        /* RX process wants to run with disabled BHs, though it is not
1249         * necessary */
1250        local_bh_disable();
1251        while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)
1252                sk_backlog_rcv(sk, skb);
1253        local_bh_enable();
1254
1255        /* Clear memory counter. */
1256        tp->ucopy.memory = 0;
1257}
1258
1259#ifdef CONFIG_NET_DMA
1260static void tcp_service_net_dma(struct sock *sk, bool wait)
1261{
1262        dma_cookie_t done, used;
1263        dma_cookie_t last_issued;
1264        struct tcp_sock *tp = tcp_sk(sk);
1265
1266        if (!tp->ucopy.dma_chan)
1267                return;
1268
1269        last_issued = tp->ucopy.dma_cookie;
1270        dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
1271
1272        do {
1273                if (dma_async_memcpy_complete(tp->ucopy.dma_chan,
1274                                              last_issued, &done,
1275                                              &used) == DMA_SUCCESS) {
1276                        /* Safe to free early-copied skbs now */
1277                        __skb_queue_purge(&sk->sk_async_wait_queue);
1278                        break;
1279                } else {
1280                        struct sk_buff *skb;
1281                        while ((skb = skb_peek(&sk->sk_async_wait_queue)) &&
1282                               (dma_async_is_complete(skb->dma_cookie, done,
1283                                                      used) == DMA_SUCCESS)) {
1284                                __skb_dequeue(&sk->sk_async_wait_queue);
1285                                kfree_skb(skb);
1286                        }
1287                }
1288        } while (wait);
1289}
1290#endif
1291
1292static inline struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
1293{
1294        struct sk_buff *skb;
1295        u32 offset;
1296
1297        skb_queue_walk(&sk->sk_receive_queue, skb) {
1298                offset = seq - TCP_SKB_CB(skb)->seq;
1299                if (tcp_hdr(skb)->syn)
1300                        offset--;
1301                if (offset < skb->len || tcp_hdr(skb)->fin) {
1302                        *off = offset;
1303                        return skb;
1304                }
1305        }
1306        return NULL;
1307}
1308
1309/*
1310 * This routine provides an alternative to tcp_recvmsg() for routines
1311 * that would like to handle copying from skbuffs directly in 'sendfile'
1312 * fashion.
1313 * Note:
1314 *      - It is assumed that the socket was locked by the caller.
1315 *      - The routine does not block.
1316 *      - At present, there is no support for reading OOB data
1317 *        or for 'peeking' the socket using this routine
1318 *        (although both would be easy to implement).
1319 */
1320int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
1321                  sk_read_actor_t recv_actor)
1322{
1323        struct sk_buff *skb;
1324        struct tcp_sock *tp = tcp_sk(sk);
1325        u32 seq = tp->copied_seq;
1326        u32 offset;
1327        int copied = 0;
1328
1329        if (sk->sk_state == TCP_LISTEN)
1330                return -ENOTCONN;
1331        while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
1332                if (offset < skb->len) {
1333                        int used;
1334                        size_t len;
1335
1336                        len = skb->len - offset;
1337                        /* Stop reading if we hit a patch of urgent data */
1338                        if (tp->urg_data) {
1339                                u32 urg_offset = tp->urg_seq - seq;
1340                                if (urg_offset < len)
1341                                        len = urg_offset;
1342                                if (!len)
1343                                        break;
1344                        }
1345                        used = recv_actor(desc, skb, offset, len);
1346                        if (used < 0) {
1347                                if (!copied)
1348                                        copied = used;
1349                                break;
1350                        } else if (used <= len) {
1351                                seq += used;
1352                                copied += used;
1353                                offset += used;
1354                        }
1355                        /*
1356                         * If recv_actor drops the lock (e.g. TCP splice
1357                         * receive) the skb pointer might be invalid when
1358                         * getting here: tcp_collapse might have deleted it
1359                         * while aggregating skbs from the socket queue.
1360                         */
1361                        skb = tcp_recv_skb(sk, seq-1, &offset);
1362                        if (!skb || (offset+1 != skb->len))
1363                                break;
1364                }
1365                if (tcp_hdr(skb)->fin) {
1366                        sk_eat_skb(sk, skb, 0);
1367                        ++seq;
1368                        break;
1369                }
1370                sk_eat_skb(sk, skb, 0);
1371                if (!desc->count)
1372                        break;
1373                tp->copied_seq = seq;
1374        }
1375        tp->copied_seq = seq;
1376
1377        tcp_rcv_space_adjust(sk);
1378
1379        /* Clean up data we have read: This will do ACK frames. */
1380        if (copied > 0)
1381                tcp_cleanup_rbuf(sk, copied);
1382        return copied;
1383}
1384
1385/*
1386 *      This routine copies from a sock struct into the user buffer.
1387 *
1388 *      Technical note: in 2.3 we work on _locked_ socket, so that
1389 *      tricks with *seq access order and skb->users are not required.
1390 *      Probably, code can be easily improved even more.
1391 */
1392
1393int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
1394                size_t len, int nonblock, int flags, int *addr_len)
1395{
1396        struct tcp_sock *tp = tcp_sk(sk);
1397        int copied = 0;
1398        u32 peek_seq;
1399        u32 *seq;
1400        unsigned long used;
1401        int err;
1402        int target;             /* Read at least this many bytes */
1403        long timeo;
1404        struct task_struct *user_recv = NULL;
1405        int copied_early = 0;
1406        struct sk_buff *skb;
1407        u32 urg_hole = 0;
1408
1409        lock_sock(sk);
1410
1411        TCP_CHECK_TIMER(sk);
1412
1413        err = -ENOTCONN;
1414        if (sk->sk_state == TCP_LISTEN)
1415                goto out;
1416
1417        timeo = sock_rcvtimeo(sk, nonblock);
1418
1419        /* Urgent data needs to be handled specially. */
1420        if (flags & MSG_OOB)
1421                goto recv_urg;
1422
1423        seq = &tp->copied_seq;
1424        if (flags & MSG_PEEK) {
1425                peek_seq = tp->copied_seq;
1426                seq = &peek_seq;
1427        }
1428
1429        target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
1430
1431#ifdef CONFIG_NET_DMA
1432        tp->ucopy.dma_chan = NULL;
1433        preempt_disable();
1434        skb = skb_peek_tail(&sk->sk_receive_queue);
1435        {
1436                int available = 0;
1437
1438                if (skb)
1439                        available = TCP_SKB_CB(skb)->seq + skb->len - (*seq);
1440                if ((available < target) &&
1441                    (len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) &&
1442                    !sysctl_tcp_low_latency &&
1443                    dma_find_channel(DMA_MEMCPY)) {
1444                        preempt_enable_no_resched();
1445                        tp->ucopy.pinned_list =
1446                                        dma_pin_iovec_pages(msg->msg_iov, len);
1447                } else {
1448                        preempt_enable_no_resched();
1449                }
1450        }
1451#endif
1452
1453        do {
1454                u32 offset;
1455
1456                /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
1457                if (tp->urg_data && tp->urg_seq == *seq) {
1458                        if (copied)
1459                                break;
1460                        if (signal_pending(current)) {
1461                                copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
1462                                break;
1463                        }
1464                }
1465
1466                /* Next get a buffer. */
1467
1468                skb_queue_walk(&sk->sk_receive_queue, skb) {
1469                        /* Now that we have two receive queues this
1470                         * shouldn't happen.
1471                         */
1472                        if (WARN(before(*seq, TCP_SKB_CB(skb)->seq),
1473                             KERN_INFO "recvmsg bug: copied %X "
1474                                       "seq %X rcvnxt %X fl %X\n", *seq,
1475                                       TCP_SKB_CB(skb)->seq, tp->rcv_nxt,
1476                                       flags))
1477                                break;
1478
1479                        offset = *seq - TCP_SKB_CB(skb)->seq;
1480                        if (tcp_hdr(skb)->syn)
1481                                offset--;
1482                        if (offset < skb->len)
1483                                goto found_ok_skb;
1484                        if (tcp_hdr(skb)->fin)
1485                                goto found_fin_ok;
1486                        WARN(!(flags & MSG_PEEK), KERN_INFO "recvmsg bug 2: "
1487                                        "copied %X seq %X rcvnxt %X fl %X\n",
1488                                        *seq, TCP_SKB_CB(skb)->seq,
1489                                        tp->rcv_nxt, flags);
1490                }
1491
1492                /* Well, if we have backlog, try to process it now yet. */
1493
1494                if (copied >= target && !sk->sk_backlog.tail)
1495                        break;
1496
1497                if (copied) {
1498                        if (sk->sk_err ||
1499                            sk->sk_state == TCP_CLOSE ||
1500                            (sk->sk_shutdown & RCV_SHUTDOWN) ||
1501                            !timeo ||
1502                            signal_pending(current))
1503                                break;
1504                } else {
1505                        if (sock_flag(sk, SOCK_DONE))
1506                                break;
1507
1508                        if (sk->sk_err) {
1509                                copied = sock_error(sk);
1510                                break;
1511                        }
1512
1513                        if (sk->sk_shutdown & RCV_SHUTDOWN)
1514                                break;
1515
1516                        if (sk->sk_state == TCP_CLOSE) {
1517                                if (!sock_flag(sk, SOCK_DONE)) {
1518                                        /* This occurs when user tries to read
1519                                         * from never connected socket.
1520                                         */
1521                                        copied = -ENOTCONN;
1522                                        break;
1523                                }
1524                                break;
1525                        }
1526
1527                        if (!timeo) {
1528                                copied = -EAGAIN;
1529                                break;
1530                        }
1531
1532                        if (signal_pending(current)) {
1533                                copied = sock_intr_errno(timeo);
1534                                break;
1535                        }
1536                }
1537
1538                tcp_cleanup_rbuf(sk, copied);
1539
1540                if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) {
1541                        /* Install new reader */
1542                        if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) {
1543                                user_recv = current;
1544                                tp->ucopy.task = user_recv;
1545                                tp->ucopy.iov = msg->msg_iov;
1546                        }
1547
1548                        tp->ucopy.len = len;
1549
1550                        WARN_ON(tp->copied_seq != tp->rcv_nxt &&
1551                                !(flags & (MSG_PEEK | MSG_TRUNC)));
1552
1553                        /* Ugly... If prequeue is not empty, we have to
1554                         * process it before releasing socket, otherwise
1555                         * order will be broken at second iteration.
1556                         * More elegant solution is required!!!
1557                         *
1558                         * Look: we have the following (pseudo)queues:
1559                         *
1560                         * 1. packets in flight
1561                         * 2. backlog
1562                         * 3. prequeue
1563                         * 4. receive_queue
1564                         *
1565                         * Each queue can be processed only if the next ones
1566                         * are empty. At this point we have empty receive_queue.
1567                         * But prequeue _can_ be not empty after 2nd iteration,
1568                         * when we jumped to start of loop because backlog
1569                         * processing added something to receive_queue.
1570                         * We cannot release_sock(), because backlog contains
1571                         * packets arrived _after_ prequeued ones.
1572                         *
1573                         * Shortly, algorithm is clear --- to process all
1574                         * the queues in order. We could make it more directly,
1575                         * requeueing packets from backlog to prequeue, if
1576                         * is not empty. It is more elegant, but eats cycles,
1577                         * unfortunately.
1578                         */
1579                        if (!skb_queue_empty(&tp->ucopy.prequeue))
1580                                goto do_prequeue;
1581
1582                        /* __ Set realtime policy in scheduler __ */
1583                }
1584
1585#ifdef CONFIG_NET_DMA
1586                if (tp->ucopy.dma_chan)
1587                        dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
1588#endif
1589                if (copied >= target) {
1590                        /* Do not sleep, just process backlog. */
1591                        release_sock(sk);
1592                        lock_sock(sk);
1593                } else
1594                        sk_wait_data(sk, &timeo);
1595
1596#ifdef CONFIG_NET_DMA
1597                tcp_service_net_dma(sk, false);  /* Don't block */
1598                tp->ucopy.wakeup = 0;
1599#endif
1600
1601                if (user_recv) {
1602                        int chunk;
1603
1604                        /* __ Restore normal policy in scheduler __ */
1605
1606                        if ((chunk = len - tp->ucopy.len) != 0) {
1607                                NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk);
1608                                len -= chunk;
1609                                copied += chunk;
1610                        }
1611
1612                        if (tp->rcv_nxt == tp->copied_seq &&
1613                            !skb_queue_empty(&tp->ucopy.prequeue)) {
1614do_prequeue:
1615                                tcp_prequeue_process(sk);
1616
1617                                if ((chunk = len - tp->ucopy.len) != 0) {
1618                                        NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1619                                        len -= chunk;
1620                                        copied += chunk;
1621                                }
1622                        }
1623                }
1624                if ((flags & MSG_PEEK) &&
1625                    (peek_seq - copied - urg_hole != tp->copied_seq)) {
1626                        if (net_ratelimit())
1627                                printk(KERN_DEBUG "TCP(%s:%d): Application bug, race in MSG_PEEK.\n",
1628                                       current->comm, task_pid_nr(current));
1629                        peek_seq = tp->copied_seq;
1630                }
1631                continue;
1632
1633        found_ok_skb:
1634                /* Ok so how much can we use? */
1635                used = skb->len - offset;
1636                if (len < used)
1637                        used = len;
1638
1639                /* Do we have urgent data here? */
1640                if (tp->urg_data) {
1641                        u32 urg_offset = tp->urg_seq - *seq;
1642                        if (urg_offset < used) {
1643                                if (!urg_offset) {
1644                                        if (!sock_flag(sk, SOCK_URGINLINE)) {
1645                                                ++*seq;
1646                                                urg_hole++;
1647                                                offset++;
1648                                                used--;
1649                                                if (!used)
1650                                                        goto skip_copy;
1651                                        }
1652                                } else
1653                                        used = urg_offset;
1654                        }
1655                }
1656
1657                if (!(flags & MSG_TRUNC)) {
1658#ifdef CONFIG_NET_DMA
1659                        if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1660                                tp->ucopy.dma_chan = dma_find_channel(DMA_MEMCPY);
1661
1662                        if (tp->ucopy.dma_chan) {
1663                                tp->ucopy.dma_cookie = dma_skb_copy_datagram_iovec(
1664                                        tp->ucopy.dma_chan, skb, offset,
1665                                        msg->msg_iov, used,
1666                                        tp->ucopy.pinned_list);
1667
1668                                if (tp->ucopy.dma_cookie < 0) {
1669
1670                                        printk(KERN_ALERT "dma_cookie < 0\n");
1671
1672                                        /* Exception. Bailout! */
1673                                        if (!copied)
1674                                                copied = -EFAULT;
1675                                        break;
1676                                }
1677
1678                                dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
1679
1680                                if ((offset + used) == skb->len)
1681                                        copied_early = 1;
1682
1683                        } else
1684#endif
1685                        {
1686                                err = skb_copy_datagram_iovec(skb, offset,
1687                                                msg->msg_iov, used);
1688                                if (err) {
1689                                        /* Exception. Bailout! */
1690                                        if (!copied)
1691                                                copied = -EFAULT;
1692                                        break;
1693                                }
1694                        }
1695                }
1696
1697                *seq += used;
1698                copied += used;
1699                len -= used;
1700
1701                tcp_rcv_space_adjust(sk);
1702
1703skip_copy:
1704                if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) {
1705                        tp->urg_data = 0;
1706                        tcp_fast_path_check(sk);
1707                }
1708                if (used + offset < skb->len)
1709                        continue;
1710
1711                if (tcp_hdr(skb)->fin)
1712                        goto found_fin_ok;
1713                if (!(flags & MSG_PEEK)) {
1714                        sk_eat_skb(sk, skb, copied_early);
1715                        copied_early = 0;
1716                }
1717                continue;
1718
1719        found_fin_ok:
1720                /* Process the FIN. */
1721                ++*seq;
1722                if (!(flags & MSG_PEEK)) {
1723                        sk_eat_skb(sk, skb, copied_early);
1724                        copied_early = 0;
1725                }
1726                break;
1727        } while (len > 0);
1728
1729        if (user_recv) {
1730                if (!skb_queue_empty(&tp->ucopy.prequeue)) {
1731                        int chunk;
1732
1733                        tp->ucopy.len = copied > 0 ? len : 0;
1734
1735                        tcp_prequeue_process(sk);
1736
1737                        if (copied > 0 && (chunk = len - tp->ucopy.len) != 0) {
1738                                NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1739                                len -= chunk;
1740                                copied += chunk;
1741                        }
1742                }
1743
1744                tp->ucopy.task = NULL;
1745                tp->ucopy.len = 0;
1746        }
1747
1748#ifdef CONFIG_NET_DMA
1749        tcp_service_net_dma(sk, true);  /* Wait for queue to drain */
1750        tp->ucopy.dma_chan = NULL;
1751
1752        if (tp->ucopy.pinned_list) {
1753                dma_unpin_iovec_pages(tp->ucopy.pinned_list);
1754                tp->ucopy.pinned_list = NULL;
1755        }
1756#endif
1757
1758        /* According to UNIX98, msg_name/msg_namelen are ignored
1759         * on connected socket. I was just happy when found this 8) --ANK
1760         */
1761
1762        /* Clean up data we have read: This will do ACK frames. */
1763        tcp_cleanup_rbuf(sk, copied);
1764
1765        TCP_CHECK_TIMER(sk);
1766        release_sock(sk);
1767        return copied;
1768
1769out:
1770        TCP_CHECK_TIMER(sk);
1771        release_sock(sk);
1772        return err;
1773
1774recv_urg:
1775        err = tcp_recv_urg(sk, msg, len, flags);
1776        goto out;
1777}
1778
1779void tcp_set_state(struct sock *sk, int state)
1780{
1781        int oldstate = sk->sk_state;
1782
1783        switch (state) {
1784        case TCP_ESTABLISHED:
1785                if (oldstate != TCP_ESTABLISHED)
1786                        TCP_INC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1787                break;
1788
1789        case TCP_CLOSE:
1790                if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
1791                        TCP_INC_STATS(sock_net(sk), TCP_MIB_ESTABRESETS);
1792
1793                sk->sk_prot->unhash(sk);
1794                if (inet_csk(sk)->icsk_bind_hash &&
1795                    !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
1796                        inet_put_port(sk);
1797                /* fall through */
1798        default:
1799                if (oldstate == TCP_ESTABLISHED)
1800                        TCP_DEC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1801        }
1802
1803        /* Change state AFTER socket is unhashed to avoid closed
1804         * socket sitting in hash tables.
1805         */
1806        sk->sk_state = state;
1807
1808#ifdef STATE_TRACE
1809        SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n", sk, statename[oldstate], statename[state]);
1810#endif
1811}
1812EXPORT_SYMBOL_GPL(tcp_set_state);
1813
1814/*
1815 *      State processing on a close. This implements the state shift for
1816 *      sending our FIN frame. Note that we only send a FIN for some
1817 *      states. A shutdown() may have already sent the FIN, or we may be
1818 *      closed.
1819 */
1820
1821static const unsigned char new_state[16] = {
1822  /* current state:        new state:      action:      */
1823  /* (Invalid)          */ TCP_CLOSE,
1824  /* TCP_ESTABLISHED    */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1825  /* TCP_SYN_SENT       */ TCP_CLOSE,
1826  /* TCP_SYN_RECV       */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1827  /* TCP_FIN_WAIT1      */ TCP_FIN_WAIT1,
1828  /* TCP_FIN_WAIT2      */ TCP_FIN_WAIT2,
1829  /* TCP_TIME_WAIT      */ TCP_CLOSE,
1830  /* TCP_CLOSE          */ TCP_CLOSE,
1831  /* TCP_CLOSE_WAIT     */ TCP_LAST_ACK  | TCP_ACTION_FIN,
1832  /* TCP_LAST_ACK       */ TCP_LAST_ACK,
1833  /* TCP_LISTEN         */ TCP_CLOSE,
1834  /* TCP_CLOSING        */ TCP_CLOSING,
1835};
1836
1837static int tcp_close_state(struct sock *sk)
1838{
1839        int next = (int)new_state[sk->sk_state];
1840        int ns = next & TCP_STATE_MASK;
1841
1842        tcp_set_state(sk, ns);
1843
1844        return next & TCP_ACTION_FIN;
1845}
1846
1847/*
1848 *      Shutdown the sending side of a connection. Much like close except
1849 *      that we don't receive shut down or sock_set_flag(sk, SOCK_DEAD).
1850 */
1851
1852void tcp_shutdown(struct sock *sk, int how)
1853{
1854        /*      We need to grab some memory, and put together a FIN,
1855         *      and then put it into the queue to be sent.
1856         *              Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
1857         */
1858        if (!(how & SEND_SHUTDOWN))
1859                return;
1860
1861        /* If we've already sent a FIN, or it's a closed state, skip this. */
1862        if ((1 << sk->sk_state) &
1863            (TCPF_ESTABLISHED | TCPF_SYN_SENT |
1864             TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
1865                /* Clear out any half completed packets.  FIN if needed. */
1866                if (tcp_close_state(sk))
1867                        tcp_send_fin(sk);
1868        }
1869}
1870
1871void tcp_close(struct sock *sk, long timeout)
1872{
1873        struct sk_buff *skb;
1874        int data_was_unread = 0;
1875        int state;
1876
1877        lock_sock(sk);
1878        sk->sk_shutdown = SHUTDOWN_MASK;
1879
1880        if (sk->sk_state == TCP_LISTEN) {
1881                tcp_set_state(sk, TCP_CLOSE);
1882
1883                /* Special case. */
1884                inet_csk_listen_stop(sk);
1885
1886                goto adjudge_to_death;
1887        }
1888
1889        /*  We need to flush the recv. buffs.  We do this only on the
1890         *  descriptor close, not protocol-sourced closes, because the
1891         *  reader process may not have drained the data yet!
1892         */
1893        while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
1894                u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq -
1895                          tcp_hdr(skb)->fin;
1896                data_was_unread += len;
1897                __kfree_skb(skb);
1898        }
1899
1900        sk_mem_reclaim(sk);
1901
1902        /* As outlined in RFC 2525, section 2.17, we send a RST here because
1903         * data was lost. To witness the awful effects of the old behavior of
1904         * always doing a FIN, run an older 2.1.x kernel or 2.0.x, start a bulk
1905         * GET in an FTP client, suspend the process, wait for the client to
1906         * advertise a zero window, then kill -9 the FTP client, wheee...
1907         * Note: timeout is always zero in such a case.
1908         */
1909        if (data_was_unread) {
1910                /* Unread data was tossed, zap the connection. */
1911                NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPABORTONCLOSE);
1912                tcp_set_state(sk, TCP_CLOSE);
1913                tcp_send_active_reset(sk, sk->sk_allocation);
1914        } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
1915                /* Check zero linger _after_ checking for unread data. */
1916                sk->sk_prot->disconnect(sk, 0);
1917                NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
1918        } else if (tcp_close_state(sk)) {
1919                /* We FIN if the application ate all the data before
1920                 * zapping the connection.
1921                 */
1922
1923                /* RED-PEN. Formally speaking, we have broken TCP state
1924                 * machine. State transitions:
1925                 *
1926                 * TCP_ESTABLISHED -> TCP_FIN_WAIT1
1927                 * TCP_SYN_RECV -> TCP_FIN_WAIT1 (forget it, it's impossible)
1928                 * TCP_CLOSE_WAIT -> TCP_LAST_ACK
1929                 *
1930                 * are legal only when FIN has been sent (i.e. in window),
1931                 * rather than queued out of window. Purists blame.
1932                 *
1933                 * F.e. "RFC state" is ESTABLISHED,
1934                 * if Linux state is FIN-WAIT-1, but FIN is still not sent.
1935                 *
1936                 * The visible declinations are that sometimes
1937                 * we enter time-wait state, when it is not required really
1938                 * (harmless), do not send active resets, when they are
1939                 * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when
1940                 * they look as CLOSING or LAST_ACK for Linux)
1941                 * Probably, I missed some more holelets.
1942                 *                                              --ANK
1943                 */
1944                tcp_send_fin(sk);
1945        }
1946
1947        sk_stream_wait_close(sk, timeout);
1948
1949adjudge_to_death:
1950        state = sk->sk_state;
1951        sock_hold(sk);
1952        sock_orphan(sk);
1953
1954        /* It is the last release_sock in its life. It will remove backlog. */
1955        release_sock(sk);
1956
1957
1958        /* Now socket is owned by kernel and we acquire BH lock
1959           to finish close. No need to check for user refs.
1960         */
1961        local_bh_disable();
1962        bh_lock_sock(sk);
1963        WARN_ON(sock_owned_by_user(sk));
1964
1965        percpu_counter_inc(sk->sk_prot->orphan_count);
1966
1967        /* Have we already been destroyed by a softirq or backlog? */
1968        if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
1969                goto out;
1970
1971        /*      This is a (useful) BSD violating of the RFC. There is a
1972         *      problem with TCP as specified in that the other end could
1973         *      keep a socket open forever with no application left this end.
1974         *      We use a 3 minute timeout (about the same as BSD) then kill
1975         *      our end. If they send after that then tough - BUT: long enough
1976         *      that we won't make the old 4*rto = almost no time - whoops
1977         *      reset mistake.
1978         *
1979         *      Nope, it was not mistake. It is really desired behaviour
1980         *      f.e. on http servers, when such sockets are useless, but
1981         *      consume significant resources. Let's do it with special
1982         *      linger2 option.                                 --ANK
1983         */
1984
1985        if (sk->sk_state == TCP_FIN_WAIT2) {
1986                struct tcp_sock *tp = tcp_sk(sk);
1987                if (tp->linger2 < 0) {
1988                        tcp_set_state(sk, TCP_CLOSE);
1989                        tcp_send_active_reset(sk, GFP_ATOMIC);
1990                        NET_INC_STATS_BH(sock_net(sk),
1991                                        LINUX_MIB_TCPABORTONLINGER);
1992                } else {
1993                        const int tmo = tcp_fin_time(sk);
1994
1995                        if (tmo > TCP_TIMEWAIT_LEN) {
1996                                inet_csk_reset_keepalive_timer(sk,
1997                                                tmo - TCP_TIMEWAIT_LEN);
1998                        } else {
1999                                tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
2000                                goto out;
2001                        }
2002                }
2003        }
2004        if (sk->sk_state != TCP_CLOSE) {
2005                int orphan_count = percpu_counter_read_positive(
2006                                                sk->sk_prot->orphan_count);
2007
2008                sk_mem_reclaim(sk);
2009                if (tcp_too_many_orphans(sk, orphan_count)) {
2010                        if (net_ratelimit())
2011                                printk(KERN_INFO "TCP: too many of orphaned "
2012                                       "sockets\n");
2013                        tcp_set_state(sk, TCP_CLOSE);
2014                        tcp_send_active_reset(sk, GFP_ATOMIC);
2015                        NET_INC_STATS_BH(sock_net(sk),
2016                                        LINUX_MIB_TCPABORTONMEMORY);
2017                }
2018        }
2019
2020        if (sk->sk_state == TCP_CLOSE)
2021                inet_csk_destroy_sock(sk);
2022        /* Otherwise, socket is reprieved until protocol close. */
2023
2024out:
2025        bh_unlock_sock(sk);
2026        local_bh_enable();
2027        sock_put(sk);
2028}
2029
2030/* These states need RST on ABORT according to RFC793 */
2031
2032static inline int tcp_need_reset(int state)
2033{
2034        return (1 << state) &
2035               (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
2036                TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
2037}
2038
2039int tcp_disconnect(struct sock *sk, int flags)
2040{
2041        struct inet_sock *inet = inet_sk(sk);
2042        struct inet_connection_sock *icsk = inet_csk(sk);
2043        struct tcp_sock *tp = tcp_sk(sk);
2044        int err = 0;
2045        int old_state = sk->sk_state;
2046
2047        if (old_state != TCP_CLOSE)
2048                tcp_set_state(sk, TCP_CLOSE);
2049
2050        /* ABORT function of RFC793 */
2051        if (old_state == TCP_LISTEN) {
2052                inet_csk_listen_stop(sk);
2053        } else if (tcp_need_reset(old_state) ||
2054                   (tp->snd_nxt != tp->write_seq &&
2055                    (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
2056                /* The last check adjusts for discrepancy of Linux wrt. RFC
2057                 * states
2058                 */
2059                tcp_send_active_reset(sk, gfp_any());
2060                sk->sk_err = ECONNRESET;
2061        } else if (old_state == TCP_SYN_SENT)
2062                sk->sk_err = ECONNRESET;
2063
2064        tcp_clear_xmit_timers(sk);
2065        __skb_queue_purge(&sk->sk_receive_queue);
2066        tcp_write_queue_purge(sk);
2067        __skb_queue_purge(&tp->out_of_order_queue);
2068#ifdef CONFIG_NET_DMA
2069        __skb_queue_purge(&sk->sk_async_wait_queue);
2070#endif
2071
2072        inet->inet_dport = 0;
2073
2074        if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
2075                inet_reset_saddr(sk);
2076
2077        sk->sk_shutdown = 0;
2078        sock_reset_flag(sk, SOCK_DONE);
2079        tp->srtt = 0;
2080        if ((tp->write_seq += tp->max_window + 2) == 0)
2081                tp->write_seq = 1;
2082        icsk->icsk_backoff = 0;
2083        tp->snd_cwnd = 2;
2084        icsk->icsk_probes_out = 0;
2085        tp->packets_out = 0;
2086        tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
2087        tp->snd_cwnd_cnt = 0;
2088        tp->bytes_acked = 0;
2089        tp->window_clamp = 0;
2090        tcp_set_ca_state(sk, TCP_CA_Open);
2091        tcp_clear_retrans(tp);
2092        inet_csk_delack_init(sk);
2093        tcp_init_send_head(sk);
2094        memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
2095        __sk_dst_reset(sk);
2096
2097        WARN_ON(inet->inet_num && !icsk->icsk_bind_hash);
2098
2099        sk->sk_error_report(sk);
2100        return err;
2101}
2102
2103/*
2104 *      Socket option code for TCP.
2105 */
2106static int do_tcp_setsockopt(struct sock *sk, int level,
2107                int optname, char __user *optval, unsigned int optlen)
2108{
2109        struct tcp_sock *tp = tcp_sk(sk);
2110        struct inet_connection_sock *icsk = inet_csk(sk);
2111        int val;
2112        int err = 0;
2113
2114        /* These are data/string values, all the others are ints */
2115        switch (optname) {
2116        case TCP_CONGESTION: {
2117                char name[TCP_CA_NAME_MAX];
2118
2119                if (optlen < 1)
2120                        return -EINVAL;
2121
2122                val = strncpy_from_user(name, optval,
2123                                        min_t(long, TCP_CA_NAME_MAX-1, optlen));
2124                if (val < 0)
2125                        return -EFAULT;
2126                name[val] = 0;
2127
2128                lock_sock(sk);
2129                err = tcp_set_congestion_control(sk, name);
2130                release_sock(sk);
2131                return err;
2132        }
2133        case TCP_COOKIE_TRANSACTIONS: {
2134                struct tcp_cookie_transactions ctd;
2135                struct tcp_cookie_values *cvp = NULL;
2136
2137                if (sizeof(ctd) > optlen)
2138                        return -EINVAL;
2139                if (copy_from_user(&ctd, optval, sizeof(ctd)))
2140                        return -EFAULT;
2141
2142                if (ctd.tcpct_used > sizeof(ctd.tcpct_value) ||
2143                    ctd.tcpct_s_data_desired > TCP_MSS_DESIRED)
2144                        return -EINVAL;
2145
2146                if (ctd.tcpct_cookie_desired == 0) {
2147                        /* default to global value */
2148                } else if ((0x1 & ctd.tcpct_cookie_desired) ||
2149                           ctd.tcpct_cookie_desired > TCP_COOKIE_MAX ||
2150                           ctd.tcpct_cookie_desired < TCP_COOKIE_MIN) {
2151                        return -EINVAL;
2152                }
2153
2154                if (TCP_COOKIE_OUT_NEVER & ctd.tcpct_flags) {
2155                        /* Supercedes all other values */
2156                        lock_sock(sk);
2157                        if (tp->cookie_values != NULL) {
2158                                kref_put(&tp->cookie_values->kref,
2159                                         tcp_cookie_values_release);
2160                                tp->cookie_values = NULL;
2161                        }
2162                        tp->rx_opt.cookie_in_always = 0; /* false */
2163                        tp->rx_opt.cookie_out_never = 1; /* true */
2164                        release_sock(sk);
2165                        return err;
2166                }
2167
2168                /* Allocate ancillary memory before locking.
2169                 */
2170                if (ctd.tcpct_used > 0 ||
2171                    (tp->cookie_values == NULL &&
2172                     (sysctl_tcp_cookie_size > 0 ||
2173                      ctd.tcpct_cookie_desired > 0 ||
2174                      ctd.tcpct_s_data_desired > 0))) {
2175                        cvp = kzalloc(sizeof(*cvp) + ctd.tcpct_used,
2176                                      GFP_KERNEL);
2177                        if (cvp == NULL)
2178                                return -ENOMEM;
2179                }
2180                lock_sock(sk);
2181                tp->rx_opt.cookie_in_always =
2182                        (TCP_COOKIE_IN_ALWAYS & ctd.tcpct_flags);
2183                tp->rx_opt.cookie_out_never = 0; /* false */
2184
2185                if (tp->cookie_values != NULL) {
2186                        if (cvp != NULL) {
2187                                /* Changed values are recorded by a changed
2188                                 * pointer, ensuring the cookie will differ,
2189                                 * without separately hashing each value later.
2190                                 */
2191                                kref_put(&tp->cookie_values->kref,
2192                                         tcp_cookie_values_release);
2193                                kref_init(&cvp->kref);
2194                                tp->cookie_values = cvp;
2195                        } else {
2196                                cvp = tp->cookie_values;
2197                        }
2198                }
2199                if (cvp != NULL) {
2200                        cvp->cookie_desired = ctd.tcpct_cookie_desired;
2201
2202                        if (ctd.tcpct_used > 0) {
2203                                memcpy(cvp->s_data_payload, ctd.tcpct_value,
2204                                       ctd.tcpct_used);
2205                                cvp->s_data_desired = ctd.tcpct_used;
2206                                cvp->s_data_constant = 1; /* true */
2207                        } else {
2208                                /* No constant payload data. */
2209                                cvp->s_data_desired = ctd.tcpct_s_data_desired;
2210                                cvp->s_data_constant = 0; /* false */
2211                        }
2212                }
2213                release_sock(sk);
2214                return err;
2215        }
2216        default:
2217                /* fallthru */
2218                break;
2219        }
2220
2221        if (optlen < sizeof(int))
2222                return -EINVAL;
2223
2224        if (get_user(val, (int __user *)optval))
2225                return -EFAULT;
2226
2227        lock_sock(sk);
2228
2229        switch (optname) {
2230        case TCP_MAXSEG:
2231                /* Values greater than interface MTU won't take effect. However
2232                 * at the point when this call is done we typically don't yet
2233                 * know which interface is going to be used */
2234                if (val < 8 || val > MAX_TCP_WINDOW) {
2235                        err = -EINVAL;
2236                        break;
2237                }
2238                tp->rx_opt.user_mss = val;
2239                break;
2240
2241        case TCP_NODELAY:
2242                if (val) {
2243                        /* TCP_NODELAY is weaker than TCP_CORK, so that
2244                         * this option on corked socket is remembered, but
2245                         * it is not activated until cork is cleared.
2246                         *
2247                         * However, when TCP_NODELAY is set we make
2248                         * an explicit push, which overrides even TCP_CORK
2249                         * for currently queued segments.
2250                         */
2251                        tp->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
2252                        tcp_push_pending_frames(sk);
2253                } else {
2254                        tp->nonagle &= ~TCP_NAGLE_OFF;
2255                }
2256                break;
2257
2258        case TCP_THIN_LINEAR_TIMEOUTS:
2259                if (val < 0 || val > 1)
2260                        err = -EINVAL;
2261                else
2262                        tp->thin_lto = val;
2263                break;
2264
2265        case TCP_THIN_DUPACK:
2266                if (val < 0 || val > 1)
2267                        err = -EINVAL;
2268                else
2269                        tp->thin_dupack = val;
2270                break;
2271
2272        case TCP_CORK:
2273                /* When set indicates to always queue non-full frames.
2274                 * Later the user clears this option and we transmit
2275                 * any pending partial frames in the queue.  This is
2276                 * meant to be used alongside sendfile() to get properly
2277                 * filled frames when the user (for example) must write
2278                 * out headers with a write() call first and then use
2279                 * sendfile to send out the data parts.
2280                 *
2281                 * TCP_CORK can be set together with TCP_NODELAY and it is
2282                 * stronger than TCP_NODELAY.
2283                 */
2284                if (val) {
2285                        tp->nonagle |= TCP_NAGLE_CORK;
2286                } else {
2287                        tp->nonagle &= ~TCP_NAGLE_CORK;
2288                        if (tp->nonagle&TCP_NAGLE_OFF)
2289                                tp->nonagle |= TCP_NAGLE_PUSH;
2290                        tcp_push_pending_frames(sk);
2291                }
2292                break;
2293
2294        case TCP_KEEPIDLE:
2295                if (val < 1 || val > MAX_TCP_KEEPIDLE)
2296                        err = -EINVAL;
2297                else {
2298                        tp->keepalive_time = val * HZ;
2299                        if (sock_flag(sk, SOCK_KEEPOPEN) &&
2300                            !((1 << sk->sk_state) &
2301                              (TCPF_CLOSE | TCPF_LISTEN))) {
2302                                u32 elapsed = keepalive_time_elapsed(tp);
2303                                if (tp->keepalive_time > elapsed)
2304                                        elapsed = tp->keepalive_time - elapsed;
2305                                else
2306                                        elapsed = 0;
2307                                inet_csk_reset_keepalive_timer(sk, elapsed);
2308                        }
2309                }
2310                break;
2311        case TCP_KEEPINTVL:
2312                if (val < 1 || val > MAX_TCP_KEEPINTVL)
2313                        err = -EINVAL;
2314                else
2315                        tp->keepalive_intvl = val * HZ;
2316                break;
2317        case TCP_KEEPCNT:
2318                if (val < 1 || val > MAX_TCP_KEEPCNT)
2319                        err = -EINVAL;
2320                else
2321                        tp->keepalive_probes = val;
2322                break;
2323        case TCP_SYNCNT:
2324                if (val < 1 || val > MAX_TCP_SYNCNT)
2325                        err = -EINVAL;
2326                else
2327                        icsk->icsk_syn_retries = val;
2328                break;
2329
2330        case TCP_LINGER2:
2331                if (val < 0)
2332                        tp->linger2 = -1;
2333                else if (val > sysctl_tcp_fin_timeout / HZ)
2334                        tp->linger2 = 0;
2335                else
2336                        tp->linger2 = val * HZ;
2337                break;
2338
2339        case TCP_DEFER_ACCEPT:
2340                /* Translate value in seconds to number of retransmits */
2341                icsk->icsk_accept_queue.rskq_defer_accept =
2342                        secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,
2343                                        TCP_RTO_MAX / HZ);
2344                break;
2345
2346        case TCP_WINDOW_CLAMP:
2347                if (!val) {
2348                        if (sk->sk_state != TCP_CLOSE) {
2349                                err = -EINVAL;
2350                                break;
2351                        }
2352                        tp->window_clamp = 0;
2353                } else
2354                        tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
2355                                                SOCK_MIN_RCVBUF / 2 : val;
2356                break;
2357
2358        case TCP_QUICKACK:
2359                if (!val) {
2360                        icsk->icsk_ack.pingpong = 1;
2361                } else {
2362                        icsk->icsk_ack.pingpong = 0;
2363                        if ((1 << sk->sk_state) &
2364                            (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
2365                            inet_csk_ack_scheduled(sk)) {
2366                                icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
2367                                tcp_cleanup_rbuf(sk, 1);
2368                                if (!(val & 1))
2369                                        icsk->icsk_ack.pingpong = 1;
2370                        }
2371                }
2372                break;
2373
2374#ifdef CONFIG_TCP_MD5SIG
2375        case TCP_MD5SIG:
2376                /* Read the IP->Key mappings from userspace */
2377                err = tp->af_specific->md5_parse(sk, optval, optlen);
2378                break;
2379#endif
2380
2381        default:
2382                err = -ENOPROTOOPT;
2383                break;
2384        }
2385
2386        release_sock(sk);
2387        return err;
2388}
2389
2390int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
2391                   unsigned int optlen)
2392{
2393        struct inet_connection_sock *icsk = inet_csk(sk);
2394
2395        if (level != SOL_TCP)
2396                return icsk->icsk_af_ops->setsockopt(sk, level, optname,
2397                                                     optval, optlen);
2398        return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2399}
2400
2401#ifdef CONFIG_COMPAT
2402int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
2403                          char __user *optval, unsigned int optlen)
2404{
2405        if (level != SOL_TCP)
2406                return inet_csk_compat_setsockopt(sk, level, optname,
2407                                                  optval, optlen);
2408        return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2409}
2410
2411EXPORT_SYMBOL(compat_tcp_setsockopt);
2412#endif
2413
2414/* Return information about state of tcp endpoint in API format. */
2415void tcp_get_info(struct sock *sk, struct tcp_info *info)
2416{
2417        struct tcp_sock *tp = tcp_sk(sk);
2418        const struct inet_connection_sock *icsk = inet_csk(sk);
2419        u32 now = tcp_time_stamp;
2420
2421        memset(info, 0, sizeof(*info));
2422
2423        info->tcpi_state = sk->sk_state;
2424        info->tcpi_ca_state = icsk->icsk_ca_state;
2425        info->tcpi_retransmits = icsk->icsk_retransmits;
2426        info->tcpi_probes = icsk->icsk_probes_out;
2427        info->tcpi_backoff = icsk->icsk_backoff;
2428
2429        if (tp->rx_opt.tstamp_ok)
2430                info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
2431        if (tcp_is_sack(tp))
2432                info->tcpi_options |= TCPI_OPT_SACK;
2433        if (tp->rx_opt.wscale_ok) {
2434                info->tcpi_options |= TCPI_OPT_WSCALE;
2435                info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
2436                info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
2437        }
2438
2439        if (tp->ecn_flags&TCP_ECN_OK)
2440                info->tcpi_options |= TCPI_OPT_ECN;
2441
2442        info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
2443        info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
2444        info->tcpi_snd_mss = tp->mss_cache;
2445        info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
2446
2447        if (sk->sk_state == TCP_LISTEN) {
2448                info->tcpi_unacked = sk->sk_ack_backlog;
2449                info->tcpi_sacked = sk->sk_max_ack_backlog;
2450        } else {
2451                info->tcpi_unacked = tp->packets_out;
2452                info->tcpi_sacked = tp->sacked_out;
2453        }
2454        info->tcpi_lost = tp->lost_out;
2455        info->tcpi_retrans = tp->retrans_out;
2456        info->tcpi_fackets = tp->fackets_out;
2457
2458        info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
2459        info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
2460        info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
2461
2462        info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
2463        info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
2464        info->tcpi_rtt = jiffies_to_usecs(tp->srtt)>>3;
2465        info->tcpi_rttvar = jiffies_to_usecs(tp->mdev)>>2;
2466        info->tcpi_snd_ssthresh = tp->snd_ssthresh;
2467        info->tcpi_snd_cwnd = tp->snd_cwnd;
2468        info->tcpi_advmss = tp->advmss;
2469        info->tcpi_reordering = tp->reordering;
2470
2471        info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3;
2472        info->tcpi_rcv_space = tp->rcvq_space.space;
2473
2474        info->tcpi_total_retrans = tp->total_retrans;
2475}
2476
2477EXPORT_SYMBOL_GPL(tcp_get_info);
2478
2479static int do_tcp_getsockopt(struct sock *sk, int level,
2480                int optname, char __user *optval, int __user *optlen)
2481{
2482        struct inet_connection_sock *icsk = inet_csk(sk);
2483        struct tcp_sock *tp = tcp_sk(sk);
2484        int val, len;
2485
2486        if (get_user(len, optlen))
2487                return -EFAULT;
2488
2489        len = min_t(unsigned int, len, sizeof(int));
2490
2491        if (len < 0)
2492                return -EINVAL;
2493
2494        switch (optname) {
2495        case TCP_MAXSEG:
2496                val = tp->mss_cache;
2497                if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
2498                        val = tp->rx_opt.user_mss;
2499                break;
2500        case TCP_NODELAY:
2501                val = !!(tp->nonagle&TCP_NAGLE_OFF);
2502                break;
2503        case TCP_CORK:
2504                val = !!(tp->nonagle&TCP_NAGLE_CORK);
2505                break;
2506        case TCP_KEEPIDLE:
2507                val = keepalive_time_when(tp) / HZ;
2508                break;
2509        case TCP_KEEPINTVL:
2510                val = keepalive_intvl_when(tp) / HZ;
2511                break;
2512        case TCP_KEEPCNT:
2513                val = keepalive_probes(tp);
2514                break;
2515        case TCP_SYNCNT:
2516                val = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
2517                break;
2518        case TCP_LINGER2:
2519                val = tp->linger2;
2520                if (val >= 0)
2521                        val = (val ? : sysctl_tcp_fin_timeout) / HZ;
2522                break;
2523        case TCP_DEFER_ACCEPT:
2524                val = retrans_to_secs(icsk->icsk_accept_queue.rskq_defer_accept,
2525                                      TCP_TIMEOUT_INIT / HZ, TCP_RTO_MAX / HZ);
2526                break;
2527        case TCP_WINDOW_CLAMP:
2528                val = tp->window_clamp;
2529                break;
2530        case TCP_INFO: {
2531                struct tcp_info info;
2532
2533                if (get_user(len, optlen))
2534                        return -EFAULT;
2535
2536                tcp_get_info(sk, &info);
2537
2538                len = min_t(unsigned int, len, sizeof(info));
2539                if (put_user(len, optlen))
2540                        return -EFAULT;
2541                if (copy_to_user(optval, &info, len))
2542                        return -EFAULT;
2543                return 0;
2544        }
2545        case TCP_QUICKACK:
2546                val = !icsk->icsk_ack.pingpong;
2547                break;
2548
2549        case TCP_CONGESTION:
2550                if (get_user(len, optlen))
2551                        return -EFAULT;
2552                len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
2553                if (put_user(len, optlen))
2554                        return -EFAULT;
2555                if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
2556                        return -EFAULT;
2557                return 0;
2558
2559        case TCP_COOKIE_TRANSACTIONS: {
2560                struct tcp_cookie_transactions ctd;
2561                struct tcp_cookie_values *cvp = tp->cookie_values;
2562
2563                if (get_user(len, optlen))
2564                        return -EFAULT;
2565                if (len < sizeof(ctd))
2566                        return -EINVAL;
2567
2568                memset(&ctd, 0, sizeof(ctd));
2569                ctd.tcpct_flags = (tp->rx_opt.cookie_in_always ?
2570                                   TCP_COOKIE_IN_ALWAYS : 0)
2571                                | (tp->rx_opt.cookie_out_never ?
2572                                   TCP_COOKIE_OUT_NEVER : 0);
2573
2574                if (cvp != NULL) {
2575                        ctd.tcpct_flags |= (cvp->s_data_in ?
2576                                            TCP_S_DATA_IN : 0)
2577                                         | (cvp->s_data_out ?
2578                                            TCP_S_DATA_OUT : 0);
2579
2580                        ctd.tcpct_cookie_desired = cvp->cookie_desired;
2581                        ctd.tcpct_s_data_desired = cvp->s_data_desired;
2582
2583                        memcpy(&ctd.tcpct_value[0], &cvp->cookie_pair[0],
2584                               cvp->cookie_pair_size);
2585                        ctd.tcpct_used = cvp->cookie_pair_size;
2586                }
2587
2588                if (put_user(sizeof(ctd), optlen))
2589                        return -EFAULT;
2590                if (copy_to_user(optval, &ctd, sizeof(ctd)))
2591                        return -EFAULT;
2592                return 0;
2593        }
2594        default:
2595                return -ENOPROTOOPT;
2596        }
2597
2598        if (put_user(len, optlen))
2599                return -EFAULT;
2600        if (copy_to_user(optval, &val, len))
2601                return -EFAULT;
2602        return 0;
2603}
2604
2605int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
2606                   int __user *optlen)
2607{
2608        struct inet_connection_sock *icsk = inet_csk(sk);
2609
2610        if (level != SOL_TCP)
2611                return icsk->icsk_af_ops->getsockopt(sk, level, optname,
2612                                                     optval, optlen);
2613        return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2614}
2615
2616#ifdef CONFIG_COMPAT
2617int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
2618                          char __user *optval, int __user *optlen)
2619{
2620        if (level != SOL_TCP)
2621                return inet_csk_compat_getsockopt(sk, level, optname,
2622                                                  optval, optlen);
2623        return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2624}
2625
2626EXPORT_SYMBOL(compat_tcp_getsockopt);
2627#endif
2628
2629struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int features)
2630{
2631        struct sk_buff *segs = ERR_PTR(-EINVAL);
2632        struct tcphdr *th;
2633        unsigned thlen;
2634        unsigned int seq;
2635        __be32 delta;
2636        unsigned int oldlen;
2637        unsigned int mss;
2638
2639        if (!pskb_may_pull(skb, sizeof(*th)))
2640                goto out;
2641
2642        th = tcp_hdr(skb);
2643        thlen = th->doff * 4;
2644        if (thlen < sizeof(*th))
2645                goto out;
2646
2647        if (!pskb_may_pull(skb, thlen))
2648                goto out;
2649
2650        oldlen = (u16)~skb->len;
2651        __skb_pull(skb, thlen);
2652
2653        mss = skb_shinfo(skb)->gso_size;
2654        if (unlikely(skb->len <= mss))
2655                goto out;
2656
2657        if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
2658                /* Packet is from an untrusted source, reset gso_segs. */
2659                int type = skb_shinfo(skb)->gso_type;
2660
2661                if (unlikely(type &
2662                             ~(SKB_GSO_TCPV4 |
2663                               SKB_GSO_DODGY |
2664                               SKB_GSO_TCP_ECN |
2665                               SKB_GSO_TCPV6 |
2666                               0) ||
2667                             !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))))
2668                        goto out;
2669
2670                skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
2671
2672                segs = NULL;
2673                goto out;
2674        }
2675
2676        segs = skb_segment(skb, features);
2677        if (IS_ERR(segs))
2678                goto out;
2679
2680        delta = htonl(oldlen + (thlen + mss));
2681
2682        skb = segs;
2683        th = tcp_hdr(skb);
2684        seq = ntohl(th->seq);
2685
2686        do {
2687                th->fin = th->psh = 0;
2688
2689                th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
2690                                       (__force u32)delta));
2691                if (skb->ip_summed != CHECKSUM_PARTIAL)
2692                        th->check =
2693                             csum_fold(csum_partial(skb_transport_header(skb),
2694                                                    thlen, skb->csum));
2695
2696                seq += mss;
2697                skb = skb->next;
2698                th = tcp_hdr(skb);
2699
2700                th->seq = htonl(seq);
2701                th->cwr = 0;
2702        } while (skb->next);
2703
2704        delta = htonl(oldlen + (skb->tail - skb->transport_header) +
2705                      skb->data_len);
2706        th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
2707                                (__force u32)delta));
2708        if (skb->ip_summed != CHECKSUM_PARTIAL)
2709                th->check = csum_fold(csum_partial(skb_transport_header(skb),
2710                                                   thlen, skb->csum));
2711
2712out:
2713        return segs;
2714}
2715EXPORT_SYMBOL(tcp_tso_segment);
2716
2717struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
2718{
2719        struct sk_buff **pp = NULL;
2720        struct sk_buff *p;
2721        struct tcphdr *th;
2722        struct tcphdr *th2;
2723        unsigned int len;
2724        unsigned int thlen;
2725        __be32 flags;
2726        unsigned int mss = 1;
2727        unsigned int hlen;
2728        unsigned int off;
2729        int flush = 1;
2730        int i;
2731
2732        off = skb_gro_offset(skb);
2733        hlen = off + sizeof(*th);
2734        th = skb_gro_header_fast(skb, off);
2735        if (skb_gro_header_hard(skb, hlen)) {
2736                th = skb_gro_header_slow(skb, hlen, off);
2737                if (unlikely(!th))
2738                        goto out;
2739        }
2740
2741        thlen = th->doff * 4;
2742        if (thlen < sizeof(*th))
2743                goto out;
2744
2745        hlen = off + thlen;
2746        if (skb_gro_header_hard(skb, hlen)) {
2747                th = skb_gro_header_slow(skb, hlen, off);
2748                if (unlikely(!th))
2749                        goto out;
2750        }
2751
2752        skb_gro_pull(skb, thlen);
2753
2754        len = skb_gro_len(skb);
2755        flags = tcp_flag_word(th);
2756
2757        for (; (p = *head); head = &p->next) {
2758                if (!NAPI_GRO_CB(p)->same_flow)
2759                        continue;
2760
2761                th2 = tcp_hdr(p);
2762
2763                if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
2764                        NAPI_GRO_CB(p)->same_flow = 0;
2765                        continue;
2766                }
2767
2768                goto found;
2769        }
2770
2771        goto out_check_final;
2772
2773found:
2774        flush = NAPI_GRO_CB(p)->flush;
2775        flush |= (__force int)(flags & TCP_FLAG_CWR);
2776        flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
2777                  ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
2778        flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
2779        for (i = sizeof(*th); i < thlen; i += 4)
2780                flush |= *(u32 *)((u8 *)th + i) ^
2781                         *(u32 *)((u8 *)th2 + i);
2782
2783        mss = skb_shinfo(p)->gso_size;
2784
2785        flush |= (len - 1) >= mss;
2786        flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
2787
2788        if (flush || skb_gro_receive(head, skb)) {
2789                mss = 1;
2790                goto out_check_final;
2791        }
2792
2793        p = *head;
2794        th2 = tcp_hdr(p);
2795        tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);
2796
2797out_check_final:
2798        flush = len < mss;
2799        flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH |
2800                                        TCP_FLAG_RST | TCP_FLAG_SYN |
2801                                        TCP_FLAG_FIN));
2802
2803        if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
2804                pp = head;
2805
2806out:
2807        NAPI_GRO_CB(skb)->flush |= flush;
2808
2809        return pp;
2810}
2811EXPORT_SYMBOL(tcp_gro_receive);
2812
2813int tcp_gro_complete(struct sk_buff *skb)
2814{
2815        struct tcphdr *th = tcp_hdr(skb);
2816
2817        skb->csum_start = skb_transport_header(skb) - skb->head;
2818        skb->csum_offset = offsetof(struct tcphdr, check);
2819        skb->ip_summed = CHECKSUM_PARTIAL;
2820
2821        skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
2822
2823        if (th->cwr)
2824                skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
2825
2826        return 0;
2827}
2828EXPORT_SYMBOL(tcp_gro_complete);
2829
2830#ifdef CONFIG_TCP_MD5SIG
2831static unsigned long tcp_md5sig_users;
2832static struct tcp_md5sig_pool * __percpu *tcp_md5sig_pool;
2833static DEFINE_SPINLOCK(tcp_md5sig_pool_lock);
2834
2835static void __tcp_free_md5sig_pool(struct tcp_md5sig_pool * __percpu *pool)
2836{
2837        int cpu;
2838        for_each_possible_cpu(cpu) {
2839                struct tcp_md5sig_pool *p = *per_cpu_ptr(pool, cpu);
2840                if (p) {
2841                        if (p->md5_desc.tfm)
2842                                crypto_free_hash(p->md5_desc.tfm);
2843                        kfree(p);
2844                }
2845        }
2846        free_percpu(pool);
2847}
2848
2849void tcp_free_md5sig_pool(void)
2850{
2851        struct tcp_md5sig_pool * __percpu *pool = NULL;
2852
2853        spin_lock_bh(&tcp_md5sig_pool_lock);
2854        if (--tcp_md5sig_users == 0) {
2855                pool = tcp_md5sig_pool;
2856                tcp_md5sig_pool = NULL;
2857        }
2858        spin_unlock_bh(&tcp_md5sig_pool_lock);
2859        if (pool)
2860                __tcp_free_md5sig_pool(pool);
2861}
2862
2863EXPORT_SYMBOL(tcp_free_md5sig_pool);
2864
2865static struct tcp_md5sig_pool * __percpu *
2866__tcp_alloc_md5sig_pool(struct sock *sk)
2867{
2868        int cpu;
2869        struct tcp_md5sig_pool * __percpu *pool;
2870
2871        pool = alloc_percpu(struct tcp_md5sig_pool *);
2872        if (!pool)
2873                return NULL;
2874
2875        for_each_possible_cpu(cpu) {
2876                struct tcp_md5sig_pool *p;
2877                struct crypto_hash *hash;
2878
2879                p = kzalloc(sizeof(*p), sk->sk_allocation);
2880                if (!p)
2881                        goto out_free;
2882                *per_cpu_ptr(pool, cpu) = p;
2883
2884                hash = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
2885                if (!hash || IS_ERR(hash))
2886                        goto out_free;
2887
2888                p->md5_desc.tfm = hash;
2889        }
2890        return pool;
2891out_free:
2892        __tcp_free_md5sig_pool(pool);
2893        return NULL;
2894}
2895
2896struct tcp_md5sig_pool * __percpu *tcp_alloc_md5sig_pool(struct sock *sk)
2897{
2898        struct tcp_md5sig_pool * __percpu *pool;
2899        int alloc = 0;
2900
2901retry:
2902        spin_lock_bh(&tcp_md5sig_pool_lock);
2903        pool = tcp_md5sig_pool;
2904        if (tcp_md5sig_users++ == 0) {
2905                alloc = 1;
2906                spin_unlock_bh(&tcp_md5sig_pool_lock);
2907        } else if (!pool) {
2908                tcp_md5sig_users--;
2909                spin_unlock_bh(&tcp_md5sig_pool_lock);
2910                cpu_relax();
2911                goto retry;
2912        } else
2913                spin_unlock_bh(&tcp_md5sig_pool_lock);
2914
2915        if (alloc) {
2916                /* we cannot hold spinlock here because this may sleep. */
2917                struct tcp_md5sig_pool * __percpu *p;
2918
2919                p = __tcp_alloc_md5sig_pool(sk);
2920                spin_lock_bh(&tcp_md5sig_pool_lock);
2921                if (!p) {
2922                        tcp_md5sig_users--;
2923                        spin_unlock_bh(&tcp_md5sig_pool_lock);
2924                        return NULL;
2925                }
2926                pool = tcp_md5sig_pool;
2927                if (pool) {
2928                        /* oops, it has already been assigned. */
2929                        spin_unlock_bh(&tcp_md5sig_pool_lock);
2930                        __tcp_free_md5sig_pool(p);
2931                } else {
2932                        tcp_md5sig_pool = pool = p;
2933                        spin_unlock_bh(&tcp_md5sig_pool_lock);
2934                }
2935        }
2936        return pool;
2937}
2938
2939EXPORT_SYMBOL(tcp_alloc_md5sig_pool);
2940
2941
2942/**
2943 *      tcp_get_md5sig_pool - get md5sig_pool for this user
2944 *
2945 *      We use percpu structure, so if we succeed, we exit with preemption
2946 *      and BH disabled, to make sure another thread or softirq handling
2947 *      wont try to get same context.
2948 */
2949struct tcp_md5sig_pool *tcp_get_md5sig_pool(void)
2950{
2951        struct tcp_md5sig_pool * __percpu *p;
2952
2953        local_bh_disable();
2954
2955        spin_lock(&tcp_md5sig_pool_lock);
2956        p = tcp_md5sig_pool;
2957        if (p)
2958                tcp_md5sig_users++;
2959        spin_unlock(&tcp_md5sig_pool_lock);
2960
2961        if (p)
2962                return *per_cpu_ptr(p, smp_processor_id());
2963
2964        local_bh_enable();
2965        return NULL;
2966}
2967EXPORT_SYMBOL(tcp_get_md5sig_pool);
2968
2969void tcp_put_md5sig_pool(void)
2970{
2971        local_bh_enable();
2972        tcp_free_md5sig_pool();
2973}
2974EXPORT_SYMBOL(tcp_put_md5sig_pool);
2975
2976int tcp_md5_hash_header(struct tcp_md5sig_pool *hp,
2977                        struct tcphdr *th)
2978{
2979        struct scatterlist sg;
2980        int err;
2981
2982        __sum16 old_checksum = th->check;
2983        th->check = 0;
2984        /* options aren't included in the hash */
2985        sg_init_one(&sg, th, sizeof(struct tcphdr));
2986        err = crypto_hash_update(&hp->md5_desc, &sg, sizeof(struct tcphdr));
2987        th->check = old_checksum;
2988        return err;
2989}
2990
2991EXPORT_SYMBOL(tcp_md5_hash_header);
2992
2993int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *hp,
2994                          struct sk_buff *skb, unsigned header_len)
2995{
2996        struct scatterlist sg;
2997        const struct tcphdr *tp = tcp_hdr(skb);
2998        struct hash_desc *desc = &hp->md5_desc;
2999        unsigned i;
3000        const unsigned head_data_len = skb_headlen(skb) > header_len ?
3001                                       skb_headlen(skb) - header_len : 0;
3002        const struct skb_shared_info *shi = skb_shinfo(skb);
3003
3004        sg_init_table(&sg, 1);
3005
3006        sg_set_buf(&sg, ((u8 *) tp) + header_len, head_data_len);
3007        if (crypto_hash_update(desc, &sg, head_data_len))
3008                return 1;
3009
3010        for (i = 0; i < shi->nr_frags; ++i) {
3011                const struct skb_frag_struct *f = &shi->frags[i];
3012                sg_set_page(&sg, f->page, f->size, f->page_offset);
3013                if (crypto_hash_update(desc, &sg, f->size))
3014                        return 1;
3015        }
3016
3017        return 0;
3018}
3019
3020EXPORT_SYMBOL(tcp_md5_hash_skb_data);
3021
3022int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, struct tcp_md5sig_key *key)
3023{
3024        struct scatterlist sg;
3025
3026        sg_init_one(&sg, key->key, key->keylen);
3027        return crypto_hash_update(&hp->md5_desc, &sg, key->keylen);
3028}
3029
3030EXPORT_SYMBOL(tcp_md5_hash_key);
3031
3032#endif
3033
3034/**
3035 * Each Responder maintains up to two secret values concurrently for
3036 * efficient secret rollover.  Each secret value has 4 states:
3037 *
3038 * Generating.  (tcp_secret_generating != tcp_secret_primary)
3039 *    Generates new Responder-Cookies, but not yet used for primary
3040 *    verification.  This is a short-term state, typically lasting only
3041 *    one round trip time (RTT).
3042 *
3043 * Primary.  (tcp_secret_generating == tcp_secret_primary)
3044 *    Used both for generation and primary verification.
3045 *
3046 * Retiring.  (tcp_secret_retiring != tcp_secret_secondary)
3047 *    Used for verification, until the first failure that can be
3048 *    verified by the newer Generating secret.  At that time, this
3049 *    cookie's state is changed to Secondary, and the Generating
3050 *    cookie's state is changed to Primary.  This is a short-term state,
3051 *    typically lasting only one round trip time (RTT).
3052 *
3053 * Secondary.  (tcp_secret_retiring == tcp_secret_secondary)
3054 *    Used for secondary verification, after primary verification
3055 *    failures.  This state lasts no more than twice the Maximum Segment
3056 *    Lifetime (2MSL).  Then, the secret is discarded.
3057 */
3058struct tcp_cookie_secret {
3059        /* The secret is divided into two parts.  The digest part is the
3060         * equivalent of previously hashing a secret and saving the state,
3061         * and serves as an initialization vector (IV).  The message part
3062         * serves as the trailing secret.
3063         */
3064        u32                             secrets[COOKIE_WORKSPACE_WORDS];
3065        unsigned long                   expires;
3066};
3067
3068#define TCP_SECRET_1MSL (HZ * TCP_PAWS_MSL)
3069#define TCP_SECRET_2MSL (HZ * TCP_PAWS_MSL * 2)
3070#define TCP_SECRET_LIFE (HZ * 600)
3071
3072static struct tcp_cookie_secret tcp_secret_one;
3073static struct tcp_cookie_secret tcp_secret_two;
3074
3075/* Essentially a circular list, without dynamic allocation. */
3076static struct tcp_cookie_secret *tcp_secret_generating;
3077static struct tcp_cookie_secret *tcp_secret_primary;
3078static struct tcp_cookie_secret *tcp_secret_retiring;
3079static struct tcp_cookie_secret *tcp_secret_secondary;
3080
3081static DEFINE_SPINLOCK(tcp_secret_locker);
3082
3083/* Select a pseudo-random word in the cookie workspace.
3084 */
3085static inline u32 tcp_cookie_work(const u32 *ws, const int n)
3086{
3087        return ws[COOKIE_DIGEST_WORDS + ((COOKIE_MESSAGE_WORDS-1) & ws[n])];
3088}
3089
3090/* Fill bakery[COOKIE_WORKSPACE_WORDS] with generator, updating as needed.
3091 * Called in softirq context.
3092 * Returns: 0 for success.
3093 */
3094int tcp_cookie_generator(u32 *bakery)
3095{
3096        unsigned long jiffy = jiffies;
3097
3098        if (unlikely(time_after_eq(jiffy, tcp_secret_generating->expires))) {
3099                spin_lock_bh(&tcp_secret_locker);
3100                if (!time_after_eq(jiffy, tcp_secret_generating->expires)) {
3101                        /* refreshed by another */
3102                        memcpy(bakery,
3103                               &tcp_secret_generating->secrets[0],
3104                               COOKIE_WORKSPACE_WORDS);
3105                } else {
3106                        /* still needs refreshing */
3107                        get_random_bytes(bakery, COOKIE_WORKSPACE_WORDS);
3108
3109                        /* The first time, paranoia assumes that the
3110                         * randomization function isn't as strong.  But,
3111                         * this secret initialization is delayed until
3112                         * the last possible moment (packet arrival).
3113                         * Although that time is observable, it is
3114                         * unpredictably variable.  Mash in the most
3115                         * volatile clock bits available, and expire the
3116                         * secret extra quickly.
3117                         */
3118                        if (unlikely(tcp_secret_primary->expires ==
3119                                     tcp_secret_secondary->expires)) {
3120                                struct timespec tv;
3121
3122                                getnstimeofday(&tv);
3123                                bakery[COOKIE_DIGEST_WORDS+0] ^=
3124                                        (u32)tv.tv_nsec;
3125
3126                                tcp_secret_secondary->expires = jiffy
3127                                        + TCP_SECRET_1MSL
3128                                        + (0x0f & tcp_cookie_work(bakery, 0));
3129                        } else {
3130                                tcp_secret_secondary->expires = jiffy
3131                                        + TCP_SECRET_LIFE
3132                                        + (0xff & tcp_cookie_work(bakery, 1));
3133                                tcp_secret_primary->expires = jiffy
3134                                        + TCP_SECRET_2MSL
3135                                        + (0x1f & tcp_cookie_work(bakery, 2));
3136                        }
3137                        memcpy(&tcp_secret_secondary->secrets[0],
3138                               bakery, COOKIE_WORKSPACE_WORDS);
3139
3140                        rcu_assign_pointer(tcp_secret_generating,
3141                                           tcp_secret_secondary);
3142                        rcu_assign_pointer(tcp_secret_retiring,
3143                                           tcp_secret_primary);
3144                        /*
3145                         * Neither call_rcu() nor synchronize_rcu() needed.
3146                         * Retiring data is not freed.  It is replaced after
3147                         * further (locked) pointer updates, and a quiet time
3148                         * (minimum 1MSL, maximum LIFE - 2MSL).
3149                         */
3150                }
3151                spin_unlock_bh(&tcp_secret_locker);
3152        } else {
3153                rcu_read_lock_bh();
3154                memcpy(bakery,
3155                       &rcu_dereference(tcp_secret_generating)->secrets[0],
3156                       COOKIE_WORKSPACE_WORDS);
3157                rcu_read_unlock_bh();
3158        }
3159        return 0;
3160}
3161EXPORT_SYMBOL(tcp_cookie_generator);
3162
3163void tcp_done(struct sock *sk)
3164{
3165        if (sk->sk_state == TCP_SYN_SENT || sk->sk_state == TCP_SYN_RECV)
3166                TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_ATTEMPTFAILS);
3167
3168        tcp_set_state(sk, TCP_CLOSE);
3169        tcp_clear_xmit_timers(sk);
3170
3171        sk->sk_shutdown = SHUTDOWN_MASK;
3172
3173        if (!sock_flag(sk, SOCK_DEAD))
3174                sk->sk_state_change(sk);
3175        else
3176                inet_csk_destroy_sock(sk);
3177}
3178EXPORT_SYMBOL_GPL(tcp_done);
3179
3180extern struct tcp_congestion_ops tcp_reno;
3181
3182static __initdata unsigned long thash_entries;
3183static int __init set_thash_entries(char *str)
3184{
3185        if (!str)
3186                return 0;
3187        thash_entries = simple_strtoul(str, &str, 0);
3188        return 1;
3189}
3190__setup("thash_entries=", set_thash_entries);
3191
3192void __init tcp_init(void)
3193{
3194        struct sk_buff *skb = NULL;
3195        unsigned long nr_pages, limit;
3196        int order, i, max_share;
3197        unsigned long jiffy = jiffies;
3198
3199        BUILD_BUG_ON(sizeof(struct tcp_skb_cb) > sizeof(skb->cb));
3200
3201        percpu_counter_init(&tcp_sockets_allocated, 0);
3202        percpu_counter_init(&tcp_orphan_count, 0);
3203        tcp_hashinfo.bind_bucket_cachep =
3204                kmem_cache_create("tcp_bind_bucket",
3205                                  sizeof(struct inet_bind_bucket), 0,
3206                                  SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
3207
3208        /* Size and allocate the main established and bind bucket
3209         * hash tables.
3210         *
3211         * The methodology is similar to that of the buffer cache.
3212         */
3213        tcp_hashinfo.ehash =
3214                alloc_large_system_hash("TCP established",
3215                                        sizeof(struct inet_ehash_bucket),
3216                                        thash_entries,
3217                                        (totalram_pages >= 128 * 1024) ?
3218                                        13 : 15,
3219                                        0,
3220                                        NULL,
3221                                        &tcp_hashinfo.ehash_mask,
3222                                        thash_entries ? 0 : 512 * 1024);
3223        for (i = 0; i <= tcp_hashinfo.ehash_mask; i++) {
3224                INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].chain, i);
3225                INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].twchain, i);
3226        }
3227        if (inet_ehash_locks_alloc(&tcp_hashinfo))
3228                panic("TCP: failed to alloc ehash_locks");
3229        tcp_hashinfo.bhash =
3230                alloc_large_system_hash("TCP bind",
3231                                        sizeof(struct inet_bind_hashbucket),
3232                                        tcp_hashinfo.ehash_mask + 1,
3233                                        (totalram_pages >= 128 * 1024) ?
3234                                        13 : 15,
3235                                        0,
3236                                        &tcp_hashinfo.bhash_size,
3237                                        NULL,
3238                                        64 * 1024);
3239        tcp_hashinfo.bhash_size = 1 << tcp_hashinfo.bhash_size;
3240        for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
3241                spin_lock_init(&tcp_hashinfo.bhash[i].lock);
3242                INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
3243        }
3244
3245        /* Try to be a bit smarter and adjust defaults depending
3246         * on available memory.
3247         */
3248        for (order = 0; ((1 << order) << PAGE_SHIFT) <
3249                        (tcp_hashinfo.bhash_size * sizeof(struct inet_bind_hashbucket));
3250                        order++)
3251                ;
3252        if (order >= 4) {
3253                tcp_death_row.sysctl_max_tw_buckets = 180000;
3254                sysctl_tcp_max_orphans = 4096 << (order - 4);
3255                sysctl_max_syn_backlog = 1024;
3256        } else if (order < 3) {
3257                tcp_death_row.sysctl_max_tw_buckets >>= (3 - order);
3258                sysctl_tcp_max_orphans >>= (3 - order);
3259                sysctl_max_syn_backlog = 128;
3260        }
3261
3262        /* Set the pressure threshold to be a fraction of global memory that
3263         * is up to 1/2 at 256 MB, decreasing toward zero with the amount of
3264         * memory, with a floor of 128 pages.
3265         */
3266        nr_pages = totalram_pages - totalhigh_pages;
3267        limit = min(nr_pages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT);
3268        limit = (limit * (nr_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
3269        limit = max(limit, 128UL);
3270        sysctl_tcp_mem[0] = limit / 4 * 3;
3271        sysctl_tcp_mem[1] = limit;
3272        sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2;
3273
3274        /* Set per-socket limits to no more than 1/128 the pressure threshold */
3275        limit = ((unsigned long)sysctl_tcp_mem[1]) << (PAGE_SHIFT - 7);
3276        max_share = min(4UL*1024*1024, limit);
3277
3278        sysctl_tcp_wmem[0] = SK_MEM_QUANTUM;
3279        sysctl_tcp_wmem[1] = 16*1024;
3280        sysctl_tcp_wmem[2] = max(64*1024, max_share);
3281
3282        sysctl_tcp_rmem[0] = SK_MEM_QUANTUM;
3283        sysctl_tcp_rmem[1] = 87380;
3284        sysctl_tcp_rmem[2] = max(87380, max_share);
3285
3286        printk(KERN_INFO "TCP: Hash tables configured "
3287               "(established %u bind %u)\n",
3288               tcp_hashinfo.ehash_mask + 1, tcp_hashinfo.bhash_size);
3289
3290        tcp_register_congestion_control(&tcp_reno);
3291
3292        memset(&tcp_secret_one.secrets[0], 0, sizeof(tcp_secret_one.secrets));
3293        memset(&tcp_secret_two.secrets[0], 0, sizeof(tcp_secret_two.secrets));
3294        tcp_secret_one.expires = jiffy; /* past due */
3295        tcp_secret_two.expires = jiffy; /* past due */
3296        tcp_secret_generating = &tcp_secret_one;
3297        tcp_secret_primary = &tcp_secret_one;
3298        tcp_secret_retiring = &tcp_secret_two;
3299        tcp_secret_secondary = &tcp_secret_two;
3300}
3301
3302EXPORT_SYMBOL(tcp_close);
3303EXPORT_SYMBOL(tcp_disconnect);
3304EXPORT_SYMBOL(tcp_getsockopt);
3305EXPORT_SYMBOL(tcp_ioctl);
3306EXPORT_SYMBOL(tcp_poll);
3307EXPORT_SYMBOL(tcp_read_sock);
3308EXPORT_SYMBOL(tcp_recvmsg);
3309EXPORT_SYMBOL(tcp_sendmsg);
3310EXPORT_SYMBOL(tcp_splice_read);
3311EXPORT_SYMBOL(tcp_sendpage);
3312EXPORT_SYMBOL(tcp_setsockopt);
3313EXPORT_SYMBOL(tcp_shutdown);
3314