linux/net/ipv4/tcp.c
<<
>>
Prefs
   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
 285long 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_long_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;
 318EXPORT_SYMBOL(tcp_memory_pressure);
 319
 320void tcp_enter_memory_pressure(struct sock *sk)
 321{
 322        if (!tcp_memory_pressure) {
 323                NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMEMORYPRESSURES);
 324                tcp_memory_pressure = 1;
 325        }
 326}
 327EXPORT_SYMBOL(tcp_enter_memory_pressure);
 328
 329/* Convert seconds to retransmits based on initial and max timeout */
 330static u8 secs_to_retrans(int seconds, int timeout, int rto_max)
 331{
 332        u8 res = 0;
 333
 334        if (seconds > 0) {
 335                int period = timeout;
 336
 337                res = 1;
 338                while (seconds > period && res < 255) {
 339                        res++;
 340                        timeout <<= 1;
 341                        if (timeout > rto_max)
 342                                timeout = rto_max;
 343                        period += timeout;
 344                }
 345        }
 346        return res;
 347}
 348
 349/* Convert retransmits to seconds based on initial and max timeout */
 350static int retrans_to_secs(u8 retrans, int timeout, int rto_max)
 351{
 352        int period = 0;
 353
 354        if (retrans > 0) {
 355                period = timeout;
 356                while (--retrans) {
 357                        timeout <<= 1;
 358                        if (timeout > rto_max)
 359                                timeout = rto_max;
 360                        period += timeout;
 361                }
 362        }
 363        return period;
 364}
 365
 366/*
 367 *      Wait for a TCP event.
 368 *
 369 *      Note that we don't need to lock the socket, as the upper poll layers
 370 *      take care of normal races (between the test and the event) and we don't
 371 *      go look at any of the socket buffers directly.
 372 */
 373unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
 374{
 375        unsigned int mask;
 376        struct sock *sk = sock->sk;
 377        struct tcp_sock *tp = tcp_sk(sk);
 378
 379        sock_poll_wait(file, sk_sleep(sk), wait);
 380        if (sk->sk_state == TCP_LISTEN)
 381                return inet_csk_listen_poll(sk);
 382
 383        /* Socket is not locked. We are protected from async events
 384         * by poll logic and correct handling of state changes
 385         * made by other threads is impossible in any case.
 386         */
 387
 388        mask = 0;
 389
 390        /*
 391         * POLLHUP is certainly not done right. But poll() doesn't
 392         * have a notion of HUP in just one direction, and for a
 393         * socket the read side is more interesting.
 394         *
 395         * Some poll() documentation says that POLLHUP is incompatible
 396         * with the POLLOUT/POLLWR flags, so somebody should check this
 397         * all. But careful, it tends to be safer to return too many
 398         * bits than too few, and you can easily break real applications
 399         * if you don't tell them that something has hung up!
 400         *
 401         * Check-me.
 402         *
 403         * Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and
 404         * our fs/select.c). It means that after we received EOF,
 405         * poll always returns immediately, making impossible poll() on write()
 406         * in state CLOSE_WAIT. One solution is evident --- to set POLLHUP
 407         * if and only if shutdown has been made in both directions.
 408         * Actually, it is interesting to look how Solaris and DUX
 409         * solve this dilemma. I would prefer, if POLLHUP were maskable,
 410         * then we could set it on SND_SHUTDOWN. BTW examples given
 411         * in Stevens' books assume exactly this behaviour, it explains
 412         * why POLLHUP is incompatible with POLLOUT.    --ANK
 413         *
 414         * NOTE. Check for TCP_CLOSE is added. The goal is to prevent
 415         * blocking on fresh not-connected or disconnected socket. --ANK
 416         */
 417        if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == TCP_CLOSE)
 418                mask |= POLLHUP;
 419        if (sk->sk_shutdown & RCV_SHUTDOWN)
 420                mask |= POLLIN | POLLRDNORM | POLLRDHUP;
 421
 422        /* Connected? */
 423        if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV)) {
 424                int target = sock_rcvlowat(sk, 0, INT_MAX);
 425
 426                if (tp->urg_seq == tp->copied_seq &&
 427                    !sock_flag(sk, SOCK_URGINLINE) &&
 428                    tp->urg_data)
 429                        target++;
 430
 431                /* Potential race condition. If read of tp below will
 432                 * escape above sk->sk_state, we can be illegally awaken
 433                 * in SYN_* states. */
 434                if (tp->rcv_nxt - tp->copied_seq >= target)
 435                        mask |= POLLIN | POLLRDNORM;
 436
 437                if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
 438                        if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
 439                                mask |= POLLOUT | POLLWRNORM;
 440                        } else {  /* send SIGIO later */
 441                                set_bit(SOCK_ASYNC_NOSPACE,
 442                                        &sk->sk_socket->flags);
 443                                set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 444
 445                                /* Race breaker. If space is freed after
 446                                 * wspace test but before the flags are set,
 447                                 * IO signal will be lost.
 448                                 */
 449                                if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk))
 450                                        mask |= POLLOUT | POLLWRNORM;
 451                        }
 452                } else
 453                        mask |= POLLOUT | POLLWRNORM;
 454
 455                if (tp->urg_data & TCP_URG_VALID)
 456                        mask |= POLLPRI;
 457        }
 458        /* This barrier is coupled with smp_wmb() in tcp_reset() */
 459        smp_rmb();
 460        if (sk->sk_err)
 461                mask |= POLLERR;
 462
 463        return mask;
 464}
 465EXPORT_SYMBOL(tcp_poll);
 466
 467int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
 468{
 469        struct tcp_sock *tp = tcp_sk(sk);
 470        int answ;
 471
 472        switch (cmd) {
 473        case SIOCINQ:
 474                if (sk->sk_state == TCP_LISTEN)
 475                        return -EINVAL;
 476
 477                lock_sock(sk);
 478                if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
 479                        answ = 0;
 480                else if (sock_flag(sk, SOCK_URGINLINE) ||
 481                         !tp->urg_data ||
 482                         before(tp->urg_seq, tp->copied_seq) ||
 483                         !before(tp->urg_seq, tp->rcv_nxt)) {
 484                        struct sk_buff *skb;
 485
 486                        answ = tp->rcv_nxt - tp->copied_seq;
 487
 488                        /* Subtract 1, if FIN is in queue. */
 489                        skb = skb_peek_tail(&sk->sk_receive_queue);
 490                        if (answ && skb)
 491                                answ -= tcp_hdr(skb)->fin;
 492                } else
 493                        answ = tp->urg_seq - tp->copied_seq;
 494                release_sock(sk);
 495                break;
 496        case SIOCATMARK:
 497                answ = tp->urg_data && tp->urg_seq == tp->copied_seq;
 498                break;
 499        case SIOCOUTQ:
 500                if (sk->sk_state == TCP_LISTEN)
 501                        return -EINVAL;
 502
 503                if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
 504                        answ = 0;
 505                else
 506                        answ = tp->write_seq - tp->snd_una;
 507                break;
 508        default:
 509                return -ENOIOCTLCMD;
 510        }
 511
 512        return put_user(answ, (int __user *)arg);
 513}
 514EXPORT_SYMBOL(tcp_ioctl);
 515
 516static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
 517{
 518        TCP_SKB_CB(skb)->flags |= TCPHDR_PSH;
 519        tp->pushed_seq = tp->write_seq;
 520}
 521
 522static inline int forced_push(struct tcp_sock *tp)
 523{
 524        return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
 525}
 526
 527static inline void skb_entail(struct sock *sk, struct sk_buff *skb)
 528{
 529        struct tcp_sock *tp = tcp_sk(sk);
 530        struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
 531
 532        skb->csum    = 0;
 533        tcb->seq     = tcb->end_seq = tp->write_seq;
 534        tcb->flags   = TCPHDR_ACK;
 535        tcb->sacked  = 0;
 536        skb_header_release(skb);
 537        tcp_add_write_queue_tail(sk, skb);
 538        sk->sk_wmem_queued += skb->truesize;
 539        sk_mem_charge(sk, skb->truesize);
 540        if (tp->nonagle & TCP_NAGLE_PUSH)
 541                tp->nonagle &= ~TCP_NAGLE_PUSH;
 542}
 543
 544static inline void tcp_mark_urg(struct tcp_sock *tp, int flags)
 545{
 546        if (flags & MSG_OOB)
 547                tp->snd_up = tp->write_seq;
 548}
 549
 550static inline void tcp_push(struct sock *sk, int flags, int mss_now,
 551                            int nonagle)
 552{
 553        if (tcp_send_head(sk)) {
 554                struct tcp_sock *tp = tcp_sk(sk);
 555
 556                if (!(flags & MSG_MORE) || forced_push(tp))
 557                        tcp_mark_push(tp, tcp_write_queue_tail(sk));
 558
 559                tcp_mark_urg(tp, flags);
 560                __tcp_push_pending_frames(sk, mss_now,
 561                                          (flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle);
 562        }
 563}
 564
 565static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
 566                                unsigned int offset, size_t len)
 567{
 568        struct tcp_splice_state *tss = rd_desc->arg.data;
 569        int ret;
 570
 571        ret = skb_splice_bits(skb, offset, tss->pipe, min(rd_desc->count, len),
 572                              tss->flags);
 573        if (ret > 0)
 574                rd_desc->count -= ret;
 575        return ret;
 576}
 577
 578static int __tcp_splice_read(struct sock *sk, struct tcp_splice_state *tss)
 579{
 580        /* Store TCP splice context information in read_descriptor_t. */
 581        read_descriptor_t rd_desc = {
 582                .arg.data = tss,
 583                .count    = tss->len,
 584        };
 585
 586        return tcp_read_sock(sk, &rd_desc, tcp_splice_data_recv);
 587}
 588
 589/**
 590 *  tcp_splice_read - splice data from TCP socket to a pipe
 591 * @sock:       socket to splice from
 592 * @ppos:       position (not valid)
 593 * @pipe:       pipe to splice to
 594 * @len:        number of bytes to splice
 595 * @flags:      splice modifier flags
 596 *
 597 * Description:
 598 *    Will read pages from given socket and fill them into a pipe.
 599 *
 600 **/
 601ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
 602                        struct pipe_inode_info *pipe, size_t len,
 603                        unsigned int flags)
 604{
 605        struct sock *sk = sock->sk;
 606        struct tcp_splice_state tss = {
 607                .pipe = pipe,
 608                .len = len,
 609                .flags = flags,
 610        };
 611        long timeo;
 612        ssize_t spliced;
 613        int ret;
 614
 615        sock_rps_record_flow(sk);
 616        /*
 617         * We can't seek on a socket input
 618         */
 619        if (unlikely(*ppos))
 620                return -ESPIPE;
 621
 622        ret = spliced = 0;
 623
 624        lock_sock(sk);
 625
 626        timeo = sock_rcvtimeo(sk, sock->file->f_flags & O_NONBLOCK);
 627        while (tss.len) {
 628                ret = __tcp_splice_read(sk, &tss);
 629                if (ret < 0)
 630                        break;
 631                else if (!ret) {
 632                        if (spliced)
 633                                break;
 634                        if (sock_flag(sk, SOCK_DONE))
 635                                break;
 636                        if (sk->sk_err) {
 637                                ret = sock_error(sk);
 638                                break;
 639                        }
 640                        if (sk->sk_shutdown & RCV_SHUTDOWN)
 641                                break;
 642                        if (sk->sk_state == TCP_CLOSE) {
 643                                /*
 644                                 * This occurs when user tries to read
 645                                 * from never connected socket.
 646                                 */
 647                                if (!sock_flag(sk, SOCK_DONE))
 648                                        ret = -ENOTCONN;
 649                                break;
 650                        }
 651                        if (!timeo) {
 652                                ret = -EAGAIN;
 653                                break;
 654                        }
 655                        sk_wait_data(sk, &timeo);
 656                        if (signal_pending(current)) {
 657                                ret = sock_intr_errno(timeo);
 658                                break;
 659                        }
 660                        continue;
 661                }
 662                tss.len -= ret;
 663                spliced += ret;
 664
 665                if (!timeo)
 666                        break;
 667                release_sock(sk);
 668                lock_sock(sk);
 669
 670                if (sk->sk_err || sk->sk_state == TCP_CLOSE ||
 671                    (sk->sk_shutdown & RCV_SHUTDOWN) ||
 672                    signal_pending(current))
 673                        break;
 674        }
 675
 676        release_sock(sk);
 677
 678        if (spliced)
 679                return spliced;
 680
 681        return ret;
 682}
 683EXPORT_SYMBOL(tcp_splice_read);
 684
 685struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp)
 686{
 687        struct sk_buff *skb;
 688
 689        /* The TCP header must be at least 32-bit aligned.  */
 690        size = ALIGN(size, 4);
 691
 692        skb = alloc_skb_fclone(size + sk->sk_prot->max_header, gfp);
 693        if (skb) {
 694                if (sk_wmem_schedule(sk, skb->truesize)) {
 695                        /*
 696                         * Make sure that we have exactly size bytes
 697                         * available to the caller, no more, no less.
 698                         */
 699                        skb_reserve(skb, skb_tailroom(skb) - size);
 700                        return skb;
 701                }
 702                __kfree_skb(skb);
 703        } else {
 704                sk->sk_prot->enter_memory_pressure(sk);
 705                sk_stream_moderate_sndbuf(sk);
 706        }
 707        return NULL;
 708}
 709
 710static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,
 711                                       int large_allowed)
 712{
 713        struct tcp_sock *tp = tcp_sk(sk);
 714        u32 xmit_size_goal, old_size_goal;
 715
 716        xmit_size_goal = mss_now;
 717
 718        if (large_allowed && sk_can_gso(sk)) {
 719                xmit_size_goal = ((sk->sk_gso_max_size - 1) -
 720                                  inet_csk(sk)->icsk_af_ops->net_header_len -
 721                                  inet_csk(sk)->icsk_ext_hdr_len -
 722                                  tp->tcp_header_len);
 723
 724                xmit_size_goal = tcp_bound_to_half_wnd(tp, xmit_size_goal);
 725
 726                /* We try hard to avoid divides here */
 727                old_size_goal = tp->xmit_size_goal_segs * mss_now;
 728
 729                if (likely(old_size_goal <= xmit_size_goal &&
 730                           old_size_goal + mss_now > xmit_size_goal)) {
 731                        xmit_size_goal = old_size_goal;
 732                } else {
 733                        tp->xmit_size_goal_segs = xmit_size_goal / mss_now;
 734                        xmit_size_goal = tp->xmit_size_goal_segs * mss_now;
 735                }
 736        }
 737
 738        return max(xmit_size_goal, mss_now);
 739}
 740
 741static int tcp_send_mss(struct sock *sk, int *size_goal, int flags)
 742{
 743        int mss_now;
 744
 745        mss_now = tcp_current_mss(sk);
 746        *size_goal = tcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));
 747
 748        return mss_now;
 749}
 750
 751static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset,
 752                         size_t psize, int flags)
 753{
 754        struct tcp_sock *tp = tcp_sk(sk);
 755        int mss_now, size_goal;
 756        int err;
 757        ssize_t copied;
 758        long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 759
 760        /* Wait for a connection to finish. */
 761        if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
 762                if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
 763                        goto out_err;
 764
 765        clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 766
 767        mss_now = tcp_send_mss(sk, &size_goal, flags);
 768        copied = 0;
 769
 770        err = -EPIPE;
 771        if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 772                goto out_err;
 773
 774        while (psize > 0) {
 775                struct sk_buff *skb = tcp_write_queue_tail(sk);
 776                struct page *page = pages[poffset / PAGE_SIZE];
 777                int copy, i, can_coalesce;
 778                int offset = poffset % PAGE_SIZE;
 779                int size = min_t(size_t, psize, PAGE_SIZE - offset);
 780
 781                if (!tcp_send_head(sk) || (copy = size_goal - skb->len) <= 0) {
 782new_segment:
 783                        if (!sk_stream_memory_free(sk))
 784                                goto wait_for_sndbuf;
 785
 786                        skb = sk_stream_alloc_skb(sk, 0, sk->sk_allocation);
 787                        if (!skb)
 788                                goto wait_for_memory;
 789
 790                        skb_entail(sk, skb);
 791                        copy = size_goal;
 792                }
 793
 794                if (copy > size)
 795                        copy = size;
 796
 797                i = skb_shinfo(skb)->nr_frags;
 798                can_coalesce = skb_can_coalesce(skb, i, page, offset);
 799                if (!can_coalesce && i >= MAX_SKB_FRAGS) {
 800                        tcp_mark_push(tp, skb);
 801                        goto new_segment;
 802                }
 803                if (!sk_wmem_schedule(sk, copy))
 804                        goto wait_for_memory;
 805
 806                if (can_coalesce) {
 807                        skb_shinfo(skb)->frags[i - 1].size += copy;
 808                } else {
 809                        get_page(page);
 810                        skb_fill_page_desc(skb, i, page, offset, copy);
 811                }
 812
 813                skb->len += copy;
 814                skb->data_len += copy;
 815                skb->truesize += copy;
 816                sk->sk_wmem_queued += copy;
 817                sk_mem_charge(sk, copy);
 818                skb->ip_summed = CHECKSUM_PARTIAL;
 819                tp->write_seq += copy;
 820                TCP_SKB_CB(skb)->end_seq += copy;
 821                skb_shinfo(skb)->gso_segs = 0;
 822
 823                if (!copied)
 824                        TCP_SKB_CB(skb)->flags &= ~TCPHDR_PSH;
 825
 826                copied += copy;
 827                poffset += copy;
 828                if (!(psize -= copy))
 829                        goto out;
 830
 831                if (skb->len < size_goal || (flags & MSG_OOB))
 832                        continue;
 833
 834                if (forced_push(tp)) {
 835                        tcp_mark_push(tp, skb);
 836                        __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
 837                } else if (skb == tcp_send_head(sk))
 838                        tcp_push_one(sk, mss_now);
 839                continue;
 840
 841wait_for_sndbuf:
 842                set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 843wait_for_memory:
 844                if (copied)
 845                        tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
 846
 847                if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
 848                        goto do_error;
 849
 850                mss_now = tcp_send_mss(sk, &size_goal, flags);
 851        }
 852
 853out:
 854        if (copied)
 855                tcp_push(sk, flags, mss_now, tp->nonagle);
 856        return copied;
 857
 858do_error:
 859        if (copied)
 860                goto out;
 861out_err:
 862        return sk_stream_error(sk, flags, err);
 863}
 864
 865int tcp_sendpage(struct sock *sk, struct page *page, int offset,
 866                 size_t size, int flags)
 867{
 868        ssize_t res;
 869
 870        if (!(sk->sk_route_caps & NETIF_F_SG) ||
 871            !(sk->sk_route_caps & NETIF_F_ALL_CSUM))
 872                return sock_no_sendpage(sk->sk_socket, page, offset, size,
 873                                        flags);
 874
 875        lock_sock(sk);
 876        TCP_CHECK_TIMER(sk);
 877        res = do_tcp_sendpages(sk, &page, offset, size, flags);
 878        TCP_CHECK_TIMER(sk);
 879        release_sock(sk);
 880        return res;
 881}
 882EXPORT_SYMBOL(tcp_sendpage);
 883
 884#define TCP_PAGE(sk)    (sk->sk_sndmsg_page)
 885#define TCP_OFF(sk)     (sk->sk_sndmsg_off)
 886
 887static inline int select_size(struct sock *sk, int sg)
 888{
 889        struct tcp_sock *tp = tcp_sk(sk);
 890        int tmp = tp->mss_cache;
 891
 892        if (sg) {
 893                if (sk_can_gso(sk))
 894                        tmp = 0;
 895                else {
 896                        int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
 897
 898                        if (tmp >= pgbreak &&
 899                            tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
 900                                tmp = pgbreak;
 901                }
 902        }
 903
 904        return tmp;
 905}
 906
 907int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 908                size_t size)
 909{
 910        struct iovec *iov;
 911        struct tcp_sock *tp = tcp_sk(sk);
 912        struct sk_buff *skb;
 913        int iovlen, flags;
 914        int mss_now, size_goal;
 915        int sg, err, copied;
 916        long timeo;
 917
 918        lock_sock(sk);
 919        TCP_CHECK_TIMER(sk);
 920
 921        flags = msg->msg_flags;
 922        timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 923
 924        /* Wait for a connection to finish. */
 925        if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
 926                if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
 927                        goto out_err;
 928
 929        /* This should be in poll */
 930        clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 931
 932        mss_now = tcp_send_mss(sk, &size_goal, flags);
 933
 934        /* Ok commence sending. */
 935        iovlen = msg->msg_iovlen;
 936        iov = msg->msg_iov;
 937        copied = 0;
 938
 939        err = -EPIPE;
 940        if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 941                goto out_err;
 942
 943        sg = sk->sk_route_caps & NETIF_F_SG;
 944
 945        while (--iovlen >= 0) {
 946                size_t seglen = iov->iov_len;
 947                unsigned char __user *from = iov->iov_base;
 948
 949                iov++;
 950
 951                while (seglen > 0) {
 952                        int copy = 0;
 953                        int max = size_goal;
 954
 955                        skb = tcp_write_queue_tail(sk);
 956                        if (tcp_send_head(sk)) {
 957                                if (skb->ip_summed == CHECKSUM_NONE)
 958                                        max = mss_now;
 959                                copy = max - skb->len;
 960                        }
 961
 962                        if (copy <= 0) {
 963new_segment:
 964                                /* Allocate new segment. If the interface is SG,
 965                                 * allocate skb fitting to single page.
 966                                 */
 967                                if (!sk_stream_memory_free(sk))
 968                                        goto wait_for_sndbuf;
 969
 970                                skb = sk_stream_alloc_skb(sk,
 971                                                          select_size(sk, sg),
 972                                                          sk->sk_allocation);
 973                                if (!skb)
 974                                        goto wait_for_memory;
 975
 976                                /*
 977                                 * Check whether we can use HW checksum.
 978                                 */
 979                                if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
 980                                        skb->ip_summed = CHECKSUM_PARTIAL;
 981
 982                                skb_entail(sk, skb);
 983                                copy = size_goal;
 984                                max = size_goal;
 985                        }
 986
 987                        /* Try to append data to the end of skb. */
 988                        if (copy > seglen)
 989                                copy = seglen;
 990
 991                        /* Where to copy to? */
 992                        if (skb_tailroom(skb) > 0) {
 993                                /* We have some space in skb head. Superb! */
 994                                if (copy > skb_tailroom(skb))
 995                                        copy = skb_tailroom(skb);
 996                                if ((err = skb_add_data(skb, from, copy)) != 0)
 997                                        goto do_fault;
 998                        } else {
 999                                int merge = 0;
1000                                int i = skb_shinfo(skb)->nr_frags;
1001                                struct page *page = TCP_PAGE(sk);
1002                                int off = TCP_OFF(sk);
1003
1004                                if (skb_can_coalesce(skb, i, page, off) &&
1005                                    off != PAGE_SIZE) {
1006                                        /* We can extend the last page
1007                                         * fragment. */
1008                                        merge = 1;
1009                                } else if (i == MAX_SKB_FRAGS || !sg) {
1010                                        /* Need to add new fragment and cannot
1011                                         * do this because interface is non-SG,
1012                                         * or because all the page slots are
1013                                         * busy. */
1014                                        tcp_mark_push(tp, skb);
1015                                        goto new_segment;
1016                                } else if (page) {
1017                                        if (off == PAGE_SIZE) {
1018                                                put_page(page);
1019                                                TCP_PAGE(sk) = page = NULL;
1020                                                off = 0;
1021                                        }
1022                                } else
1023                                        off = 0;
1024
1025                                if (copy > PAGE_SIZE - off)
1026                                        copy = PAGE_SIZE - off;
1027
1028                                if (!sk_wmem_schedule(sk, copy))
1029                                        goto wait_for_memory;
1030
1031                                if (!page) {
1032                                        /* Allocate new cache page. */
1033                                        if (!(page = sk_stream_alloc_page(sk)))
1034                                                goto wait_for_memory;
1035                                }
1036
1037                                /* Time to copy data. We are close to
1038                                 * the end! */
1039                                err = skb_copy_to_page(sk, from, skb, page,
1040                                                       off, copy);
1041                                if (err) {
1042                                        /* If this page was new, give it to the
1043                                         * socket so it does not get leaked.
1044                                         */
1045                                        if (!TCP_PAGE(sk)) {
1046                                                TCP_PAGE(sk) = page;
1047                                                TCP_OFF(sk) = 0;
1048                                        }
1049                                        goto do_error;
1050                                }
1051
1052                                /* Update the skb. */
1053                                if (merge) {
1054                                        skb_shinfo(skb)->frags[i - 1].size +=
1055                                                                        copy;
1056                                } else {
1057                                        skb_fill_page_desc(skb, i, page, off, copy);
1058                                        if (TCP_PAGE(sk)) {
1059                                                get_page(page);
1060                                        } else if (off + copy < PAGE_SIZE) {
1061                                                get_page(page);
1062                                                TCP_PAGE(sk) = page;
1063                                        }
1064                                }
1065
1066                                TCP_OFF(sk) = off + copy;
1067                        }
1068
1069                        if (!copied)
1070                                TCP_SKB_CB(skb)->flags &= ~TCPHDR_PSH;
1071
1072                        tp->write_seq += copy;
1073                        TCP_SKB_CB(skb)->end_seq += copy;
1074                        skb_shinfo(skb)->gso_segs = 0;
1075
1076                        from += copy;
1077                        copied += copy;
1078                        if ((seglen -= copy) == 0 && iovlen == 0)
1079                                goto out;
1080
1081                        if (skb->len < max || (flags & MSG_OOB))
1082                                continue;
1083
1084                        if (forced_push(tp)) {
1085                                tcp_mark_push(tp, skb);
1086                                __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
1087                        } else if (skb == tcp_send_head(sk))
1088                                tcp_push_one(sk, mss_now);
1089                        continue;
1090
1091wait_for_sndbuf:
1092                        set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
1093wait_for_memory:
1094                        if (copied)
1095                                tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
1096
1097                        if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
1098                                goto do_error;
1099
1100                        mss_now = tcp_send_mss(sk, &size_goal, flags);
1101                }
1102        }
1103
1104out:
1105        if (copied)
1106                tcp_push(sk, flags, mss_now, tp->nonagle);
1107        TCP_CHECK_TIMER(sk);
1108        release_sock(sk);
1109        return copied;
1110
1111do_fault:
1112        if (!skb->len) {
1113                tcp_unlink_write_queue(skb, sk);
1114                /* It is the one place in all of TCP, except connection
1115                 * reset, where we can be unlinking the send_head.
1116                 */
1117                tcp_check_send_head(sk, skb);
1118                sk_wmem_free_skb(sk, skb);
1119        }
1120
1121do_error:
1122        if (copied)
1123                goto out;
1124out_err:
1125        err = sk_stream_error(sk, flags, err);
1126        TCP_CHECK_TIMER(sk);
1127        release_sock(sk);
1128        return err;
1129}
1130EXPORT_SYMBOL(tcp_sendmsg);
1131
1132/*
1133 *      Handle reading urgent data. BSD has very simple semantics for
1134 *      this, no blocking and very strange errors 8)
1135 */
1136
1137static int tcp_recv_urg(struct sock *sk, struct msghdr *msg, int len, int flags)
1138{
1139        struct tcp_sock *tp = tcp_sk(sk);
1140
1141        /* No URG data to read. */
1142        if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
1143            tp->urg_data == TCP_URG_READ)
1144                return -EINVAL; /* Yes this is right ! */
1145
1146        if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
1147                return -ENOTCONN;
1148
1149        if (tp->urg_data & TCP_URG_VALID) {
1150                int err = 0;
1151                char c = tp->urg_data;
1152
1153                if (!(flags & MSG_PEEK))
1154                        tp->urg_data = TCP_URG_READ;
1155
1156                /* Read urgent data. */
1157                msg->msg_flags |= MSG_OOB;
1158
1159                if (len > 0) {
1160                        if (!(flags & MSG_TRUNC))
1161                                err = memcpy_toiovec(msg->msg_iov, &c, 1);
1162                        len = 1;
1163                } else
1164                        msg->msg_flags |= MSG_TRUNC;
1165
1166                return err ? -EFAULT : len;
1167        }
1168
1169        if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
1170                return 0;
1171
1172        /* Fixed the recv(..., MSG_OOB) behaviour.  BSD docs and
1173         * the available implementations agree in this case:
1174         * this call should never block, independent of the
1175         * blocking state of the socket.
1176         * Mike <pall@rz.uni-karlsruhe.de>
1177         */
1178        return -EAGAIN;
1179}
1180
1181/* Clean up the receive buffer for full frames taken by the user,
1182 * then send an ACK if necessary.  COPIED is the number of bytes
1183 * tcp_recvmsg has given to the user so far, it speeds up the
1184 * calculation of whether or not we must ACK for the sake of
1185 * a window update.
1186 */
1187void tcp_cleanup_rbuf(struct sock *sk, int copied)
1188{
1189        struct tcp_sock *tp = tcp_sk(sk);
1190        int time_to_ack = 0;
1191
1192#if TCP_DEBUG
1193        struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
1194
1195        WARN(skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq),
1196             "cleanup rbuf bug: copied %X seq %X rcvnxt %X\n",
1197             tp->copied_seq, TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt);
1198#endif
1199
1200        if (inet_csk_ack_scheduled(sk)) {
1201                const struct inet_connection_sock *icsk = inet_csk(sk);
1202                   /* Delayed ACKs frequently hit locked sockets during bulk
1203                    * receive. */
1204                if (icsk->icsk_ack.blocked ||
1205                    /* Once-per-two-segments ACK was not sent by tcp_input.c */
1206                    tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
1207                    /*
1208                     * If this read emptied read buffer, we send ACK, if
1209                     * connection is not bidirectional, user drained
1210                     * receive buffer and there was a small segment
1211                     * in queue.
1212                     */
1213                    (copied > 0 &&
1214                     ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) ||
1215                      ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
1216                       !icsk->icsk_ack.pingpong)) &&
1217                      !atomic_read(&sk->sk_rmem_alloc)))
1218                        time_to_ack = 1;
1219        }
1220
1221        /* We send an ACK if we can now advertise a non-zero window
1222         * which has been raised "significantly".
1223         *
1224         * Even if window raised up to infinity, do not send window open ACK
1225         * in states, where we will not receive more. It is useless.
1226         */
1227        if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
1228                __u32 rcv_window_now = tcp_receive_window(tp);
1229
1230                /* Optimize, __tcp_select_window() is not cheap. */
1231                if (2*rcv_window_now <= tp->window_clamp) {
1232                        __u32 new_window = __tcp_select_window(sk);
1233
1234                        /* Send ACK now, if this read freed lots of space
1235                         * in our buffer. Certainly, new_window is new window.
1236                         * We can advertise it now, if it is not less than current one.
1237                         * "Lots" means "at least twice" here.
1238                         */
1239                        if (new_window && new_window >= 2 * rcv_window_now)
1240                                time_to_ack = 1;
1241                }
1242        }
1243        if (time_to_ack)
1244                tcp_send_ack(sk);
1245}
1246
1247static void tcp_prequeue_process(struct sock *sk)
1248{
1249        struct sk_buff *skb;
1250        struct tcp_sock *tp = tcp_sk(sk);
1251
1252        NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPPREQUEUED);
1253
1254        /* RX process wants to run with disabled BHs, though it is not
1255         * necessary */
1256        local_bh_disable();
1257        while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)
1258                sk_backlog_rcv(sk, skb);
1259        local_bh_enable();
1260
1261        /* Clear memory counter. */
1262        tp->ucopy.memory = 0;
1263}
1264
1265#ifdef CONFIG_NET_DMA
1266static void tcp_service_net_dma(struct sock *sk, bool wait)
1267{
1268        dma_cookie_t done, used;
1269        dma_cookie_t last_issued;
1270        struct tcp_sock *tp = tcp_sk(sk);
1271
1272        if (!tp->ucopy.dma_chan)
1273                return;
1274
1275        last_issued = tp->ucopy.dma_cookie;
1276        dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
1277
1278        do {
1279                if (dma_async_memcpy_complete(tp->ucopy.dma_chan,
1280                                              last_issued, &done,
1281                                              &used) == DMA_SUCCESS) {
1282                        /* Safe to free early-copied skbs now */
1283                        __skb_queue_purge(&sk->sk_async_wait_queue);
1284                        break;
1285                } else {
1286                        struct sk_buff *skb;
1287                        while ((skb = skb_peek(&sk->sk_async_wait_queue)) &&
1288                               (dma_async_is_complete(skb->dma_cookie, done,
1289                                                      used) == DMA_SUCCESS)) {
1290                                __skb_dequeue(&sk->sk_async_wait_queue);
1291                                kfree_skb(skb);
1292                        }
1293                }
1294        } while (wait);
1295}
1296#endif
1297
1298static inline struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
1299{
1300        struct sk_buff *skb;
1301        u32 offset;
1302
1303        skb_queue_walk(&sk->sk_receive_queue, skb) {
1304                offset = seq - TCP_SKB_CB(skb)->seq;
1305                if (tcp_hdr(skb)->syn)
1306                        offset--;
1307                if (offset < skb->len || tcp_hdr(skb)->fin) {
1308                        *off = offset;
1309                        return skb;
1310                }
1311        }
1312        return NULL;
1313}
1314
1315/*
1316 * This routine provides an alternative to tcp_recvmsg() for routines
1317 * that would like to handle copying from skbuffs directly in 'sendfile'
1318 * fashion.
1319 * Note:
1320 *      - It is assumed that the socket was locked by the caller.
1321 *      - The routine does not block.
1322 *      - At present, there is no support for reading OOB data
1323 *        or for 'peeking' the socket using this routine
1324 *        (although both would be easy to implement).
1325 */
1326int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
1327                  sk_read_actor_t recv_actor)
1328{
1329        struct sk_buff *skb;
1330        struct tcp_sock *tp = tcp_sk(sk);
1331        u32 seq = tp->copied_seq;
1332        u32 offset;
1333        int copied = 0;
1334
1335        if (sk->sk_state == TCP_LISTEN)
1336                return -ENOTCONN;
1337        while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
1338                if (offset < skb->len) {
1339                        int used;
1340                        size_t len;
1341
1342                        len = skb->len - offset;
1343                        /* Stop reading if we hit a patch of urgent data */
1344                        if (tp->urg_data) {
1345                                u32 urg_offset = tp->urg_seq - seq;
1346                                if (urg_offset < len)
1347                                        len = urg_offset;
1348                                if (!len)
1349                                        break;
1350                        }
1351                        used = recv_actor(desc, skb, offset, len);
1352                        if (used < 0) {
1353                                if (!copied)
1354                                        copied = used;
1355                                break;
1356                        } else if (used <= len) {
1357                                seq += used;
1358                                copied += used;
1359                                offset += used;
1360                        }
1361                        /*
1362                         * If recv_actor drops the lock (e.g. TCP splice
1363                         * receive) the skb pointer might be invalid when
1364                         * getting here: tcp_collapse might have deleted it
1365                         * while aggregating skbs from the socket queue.
1366                         */
1367                        skb = tcp_recv_skb(sk, seq-1, &offset);
1368                        if (!skb || (offset+1 != skb->len))
1369                                break;
1370                }
1371                if (tcp_hdr(skb)->fin) {
1372                        sk_eat_skb(sk, skb, 0);
1373                        ++seq;
1374                        break;
1375                }
1376                sk_eat_skb(sk, skb, 0);
1377                if (!desc->count)
1378                        break;
1379                tp->copied_seq = seq;
1380        }
1381        tp->copied_seq = seq;
1382
1383        tcp_rcv_space_adjust(sk);
1384
1385        /* Clean up data we have read: This will do ACK frames. */
1386        if (copied > 0)
1387                tcp_cleanup_rbuf(sk, copied);
1388        return copied;
1389}
1390EXPORT_SYMBOL(tcp_read_sock);
1391
1392/*
1393 *      This routine copies from a sock struct into the user buffer.
1394 *
1395 *      Technical note: in 2.3 we work on _locked_ socket, so that
1396 *      tricks with *seq access order and skb->users are not required.
1397 *      Probably, code can be easily improved even more.
1398 */
1399
1400int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
1401                size_t len, int nonblock, int flags, int *addr_len)
1402{
1403        struct tcp_sock *tp = tcp_sk(sk);
1404        int copied = 0;
1405        u32 peek_seq;
1406        u32 *seq;
1407        unsigned long used;
1408        int err;
1409        int target;             /* Read at least this many bytes */
1410        long timeo;
1411        struct task_struct *user_recv = NULL;
1412        int copied_early = 0;
1413        struct sk_buff *skb;
1414        u32 urg_hole = 0;
1415
1416        lock_sock(sk);
1417
1418        TCP_CHECK_TIMER(sk);
1419
1420        err = -ENOTCONN;
1421        if (sk->sk_state == TCP_LISTEN)
1422                goto out;
1423
1424        timeo = sock_rcvtimeo(sk, nonblock);
1425
1426        /* Urgent data needs to be handled specially. */
1427        if (flags & MSG_OOB)
1428                goto recv_urg;
1429
1430        seq = &tp->copied_seq;
1431        if (flags & MSG_PEEK) {
1432                peek_seq = tp->copied_seq;
1433                seq = &peek_seq;
1434        }
1435
1436        target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
1437
1438#ifdef CONFIG_NET_DMA
1439        tp->ucopy.dma_chan = NULL;
1440        preempt_disable();
1441        skb = skb_peek_tail(&sk->sk_receive_queue);
1442        {
1443                int available = 0;
1444
1445                if (skb)
1446                        available = TCP_SKB_CB(skb)->seq + skb->len - (*seq);
1447                if ((available < target) &&
1448                    (len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) &&
1449                    !sysctl_tcp_low_latency &&
1450                    dma_find_channel(DMA_MEMCPY)) {
1451                        preempt_enable_no_resched();
1452                        tp->ucopy.pinned_list =
1453                                        dma_pin_iovec_pages(msg->msg_iov, len);
1454                } else {
1455                        preempt_enable_no_resched();
1456                }
1457        }
1458#endif
1459
1460        do {
1461                u32 offset;
1462
1463                /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
1464                if (tp->urg_data && tp->urg_seq == *seq) {
1465                        if (copied)
1466                                break;
1467                        if (signal_pending(current)) {
1468                                copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
1469                                break;
1470                        }
1471                }
1472
1473                /* Next get a buffer. */
1474
1475                skb_queue_walk(&sk->sk_receive_queue, skb) {
1476                        /* Now that we have two receive queues this
1477                         * shouldn't happen.
1478                         */
1479                        if (WARN(before(*seq, TCP_SKB_CB(skb)->seq),
1480                                 "recvmsg bug: copied %X seq %X rcvnxt %X fl %X\n",
1481                                 *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt,
1482                                 flags))
1483                                break;
1484
1485                        offset = *seq - TCP_SKB_CB(skb)->seq;
1486                        if (tcp_hdr(skb)->syn)
1487                                offset--;
1488                        if (offset < skb->len)
1489                                goto found_ok_skb;
1490                        if (tcp_hdr(skb)->fin)
1491                                goto found_fin_ok;
1492                        WARN(!(flags & MSG_PEEK),
1493                             "recvmsg bug 2: copied %X seq %X rcvnxt %X fl %X\n",
1494                             *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt, flags);
1495                }
1496
1497                /* Well, if we have backlog, try to process it now yet. */
1498
1499                if (copied >= target && !sk->sk_backlog.tail)
1500                        break;
1501
1502                if (copied) {
1503                        if (sk->sk_err ||
1504                            sk->sk_state == TCP_CLOSE ||
1505                            (sk->sk_shutdown & RCV_SHUTDOWN) ||
1506                            !timeo ||
1507                            signal_pending(current))
1508                                break;
1509                } else {
1510                        if (sock_flag(sk, SOCK_DONE))
1511                                break;
1512
1513                        if (sk->sk_err) {
1514                                copied = sock_error(sk);
1515                                break;
1516                        }
1517
1518                        if (sk->sk_shutdown & RCV_SHUTDOWN)
1519                                break;
1520
1521                        if (sk->sk_state == TCP_CLOSE) {
1522                                if (!sock_flag(sk, SOCK_DONE)) {
1523                                        /* This occurs when user tries to read
1524                                         * from never connected socket.
1525                                         */
1526                                        copied = -ENOTCONN;
1527                                        break;
1528                                }
1529                                break;
1530                        }
1531
1532                        if (!timeo) {
1533                                copied = -EAGAIN;
1534                                break;
1535                        }
1536
1537                        if (signal_pending(current)) {
1538                                copied = sock_intr_errno(timeo);
1539                                break;
1540                        }
1541                }
1542
1543                tcp_cleanup_rbuf(sk, copied);
1544
1545                if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) {
1546                        /* Install new reader */
1547                        if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) {
1548                                user_recv = current;
1549                                tp->ucopy.task = user_recv;
1550                                tp->ucopy.iov = msg->msg_iov;
1551                        }
1552
1553                        tp->ucopy.len = len;
1554
1555                        WARN_ON(tp->copied_seq != tp->rcv_nxt &&
1556                                !(flags & (MSG_PEEK | MSG_TRUNC)));
1557
1558                        /* Ugly... If prequeue is not empty, we have to
1559                         * process it before releasing socket, otherwise
1560                         * order will be broken at second iteration.
1561                         * More elegant solution is required!!!
1562                         *
1563                         * Look: we have the following (pseudo)queues:
1564                         *
1565                         * 1. packets in flight
1566                         * 2. backlog
1567                         * 3. prequeue
1568                         * 4. receive_queue
1569                         *
1570                         * Each queue can be processed only if the next ones
1571                         * are empty. At this point we have empty receive_queue.
1572                         * But prequeue _can_ be not empty after 2nd iteration,
1573                         * when we jumped to start of loop because backlog
1574                         * processing added something to receive_queue.
1575                         * We cannot release_sock(), because backlog contains
1576                         * packets arrived _after_ prequeued ones.
1577                         *
1578                         * Shortly, algorithm is clear --- to process all
1579                         * the queues in order. We could make it more directly,
1580                         * requeueing packets from backlog to prequeue, if
1581                         * is not empty. It is more elegant, but eats cycles,
1582                         * unfortunately.
1583                         */
1584                        if (!skb_queue_empty(&tp->ucopy.prequeue))
1585                                goto do_prequeue;
1586
1587                        /* __ Set realtime policy in scheduler __ */
1588                }
1589
1590#ifdef CONFIG_NET_DMA
1591                if (tp->ucopy.dma_chan)
1592                        dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
1593#endif
1594                if (copied >= target) {
1595                        /* Do not sleep, just process backlog. */
1596                        release_sock(sk);
1597                        lock_sock(sk);
1598                } else
1599                        sk_wait_data(sk, &timeo);
1600
1601#ifdef CONFIG_NET_DMA
1602                tcp_service_net_dma(sk, false);  /* Don't block */
1603                tp->ucopy.wakeup = 0;
1604#endif
1605
1606                if (user_recv) {
1607                        int chunk;
1608
1609                        /* __ Restore normal policy in scheduler __ */
1610
1611                        if ((chunk = len - tp->ucopy.len) != 0) {
1612                                NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk);
1613                                len -= chunk;
1614                                copied += chunk;
1615                        }
1616
1617                        if (tp->rcv_nxt == tp->copied_seq &&
1618                            !skb_queue_empty(&tp->ucopy.prequeue)) {
1619do_prequeue:
1620                                tcp_prequeue_process(sk);
1621
1622                                if ((chunk = len - tp->ucopy.len) != 0) {
1623                                        NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1624                                        len -= chunk;
1625                                        copied += chunk;
1626                                }
1627                        }
1628                }
1629                if ((flags & MSG_PEEK) &&
1630                    (peek_seq - copied - urg_hole != tp->copied_seq)) {
1631                        if (net_ratelimit())
1632                                printk(KERN_DEBUG "TCP(%s:%d): Application bug, race in MSG_PEEK.\n",
1633                                       current->comm, task_pid_nr(current));
1634                        peek_seq = tp->copied_seq;
1635                }
1636                continue;
1637
1638        found_ok_skb:
1639                /* Ok so how much can we use? */
1640                used = skb->len - offset;
1641                if (len < used)
1642                        used = len;
1643
1644                /* Do we have urgent data here? */
1645                if (tp->urg_data) {
1646                        u32 urg_offset = tp->urg_seq - *seq;
1647                        if (urg_offset < used) {
1648                                if (!urg_offset) {
1649                                        if (!sock_flag(sk, SOCK_URGINLINE)) {
1650                                                ++*seq;
1651                                                urg_hole++;
1652                                                offset++;
1653                                                used--;
1654                                                if (!used)
1655                                                        goto skip_copy;
1656                                        }
1657                                } else
1658                                        used = urg_offset;
1659                        }
1660                }
1661
1662                if (!(flags & MSG_TRUNC)) {
1663#ifdef CONFIG_NET_DMA
1664                        if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1665                                tp->ucopy.dma_chan = dma_find_channel(DMA_MEMCPY);
1666
1667                        if (tp->ucopy.dma_chan) {
1668                                tp->ucopy.dma_cookie = dma_skb_copy_datagram_iovec(
1669                                        tp->ucopy.dma_chan, skb, offset,
1670                                        msg->msg_iov, used,
1671                                        tp->ucopy.pinned_list);
1672
1673                                if (tp->ucopy.dma_cookie < 0) {
1674
1675                                        printk(KERN_ALERT "dma_cookie < 0\n");
1676
1677                                        /* Exception. Bailout! */
1678                                        if (!copied)
1679                                                copied = -EFAULT;
1680                                        break;
1681                                }
1682
1683                                dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
1684
1685                                if ((offset + used) == skb->len)
1686                                        copied_early = 1;
1687
1688                        } else
1689#endif
1690                        {
1691                                err = skb_copy_datagram_iovec(skb, offset,
1692                                                msg->msg_iov, used);
1693                                if (err) {
1694                                        /* Exception. Bailout! */
1695                                        if (!copied)
1696                                                copied = -EFAULT;
1697                                        break;
1698                                }
1699                        }
1700                }
1701
1702                *seq += used;
1703                copied += used;
1704                len -= used;
1705
1706                tcp_rcv_space_adjust(sk);
1707
1708skip_copy:
1709                if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) {
1710                        tp->urg_data = 0;
1711                        tcp_fast_path_check(sk);
1712                }
1713                if (used + offset < skb->len)
1714                        continue;
1715
1716                if (tcp_hdr(skb)->fin)
1717                        goto found_fin_ok;
1718                if (!(flags & MSG_PEEK)) {
1719                        sk_eat_skb(sk, skb, copied_early);
1720                        copied_early = 0;
1721                }
1722                continue;
1723
1724        found_fin_ok:
1725                /* Process the FIN. */
1726                ++*seq;
1727                if (!(flags & MSG_PEEK)) {
1728                        sk_eat_skb(sk, skb, copied_early);
1729                        copied_early = 0;
1730                }
1731                break;
1732        } while (len > 0);
1733
1734        if (user_recv) {
1735                if (!skb_queue_empty(&tp->ucopy.prequeue)) {
1736                        int chunk;
1737
1738                        tp->ucopy.len = copied > 0 ? len : 0;
1739
1740                        tcp_prequeue_process(sk);
1741
1742                        if (copied > 0 && (chunk = len - tp->ucopy.len) != 0) {
1743                                NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1744                                len -= chunk;
1745                                copied += chunk;
1746                        }
1747                }
1748
1749                tp->ucopy.task = NULL;
1750                tp->ucopy.len = 0;
1751        }
1752
1753#ifdef CONFIG_NET_DMA
1754        tcp_service_net_dma(sk, true);  /* Wait for queue to drain */
1755        tp->ucopy.dma_chan = NULL;
1756
1757        if (tp->ucopy.pinned_list) {
1758                dma_unpin_iovec_pages(tp->ucopy.pinned_list);
1759                tp->ucopy.pinned_list = NULL;
1760        }
1761#endif
1762
1763        /* According to UNIX98, msg_name/msg_namelen are ignored
1764         * on connected socket. I was just happy when found this 8) --ANK
1765         */
1766
1767        /* Clean up data we have read: This will do ACK frames. */
1768        tcp_cleanup_rbuf(sk, copied);
1769
1770        TCP_CHECK_TIMER(sk);
1771        release_sock(sk);
1772        return copied;
1773
1774out:
1775        TCP_CHECK_TIMER(sk);
1776        release_sock(sk);
1777        return err;
1778
1779recv_urg:
1780        err = tcp_recv_urg(sk, msg, len, flags);
1781        goto out;
1782}
1783EXPORT_SYMBOL(tcp_recvmsg);
1784
1785void tcp_set_state(struct sock *sk, int state)
1786{
1787        int oldstate = sk->sk_state;
1788
1789        switch (state) {
1790        case TCP_ESTABLISHED:
1791                if (oldstate != TCP_ESTABLISHED)
1792                        TCP_INC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1793                break;
1794
1795        case TCP_CLOSE:
1796                if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
1797                        TCP_INC_STATS(sock_net(sk), TCP_MIB_ESTABRESETS);
1798
1799                sk->sk_prot->unhash(sk);
1800                if (inet_csk(sk)->icsk_bind_hash &&
1801                    !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
1802                        inet_put_port(sk);
1803                /* fall through */
1804        default:
1805                if (oldstate == TCP_ESTABLISHED)
1806                        TCP_DEC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1807        }
1808
1809        /* Change state AFTER socket is unhashed to avoid closed
1810         * socket sitting in hash tables.
1811         */
1812        sk->sk_state = state;
1813
1814#ifdef STATE_TRACE
1815        SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n", sk, statename[oldstate], statename[state]);
1816#endif
1817}
1818EXPORT_SYMBOL_GPL(tcp_set_state);
1819
1820/*
1821 *      State processing on a close. This implements the state shift for
1822 *      sending our FIN frame. Note that we only send a FIN for some
1823 *      states. A shutdown() may have already sent the FIN, or we may be
1824 *      closed.
1825 */
1826
1827static const unsigned char new_state[16] = {
1828  /* current state:        new state:      action:      */
1829  /* (Invalid)          */ TCP_CLOSE,
1830  /* TCP_ESTABLISHED    */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1831  /* TCP_SYN_SENT       */ TCP_CLOSE,
1832  /* TCP_SYN_RECV       */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1833  /* TCP_FIN_WAIT1      */ TCP_FIN_WAIT1,
1834  /* TCP_FIN_WAIT2      */ TCP_FIN_WAIT2,
1835  /* TCP_TIME_WAIT      */ TCP_CLOSE,
1836  /* TCP_CLOSE          */ TCP_CLOSE,
1837  /* TCP_CLOSE_WAIT     */ TCP_LAST_ACK  | TCP_ACTION_FIN,
1838  /* TCP_LAST_ACK       */ TCP_LAST_ACK,
1839  /* TCP_LISTEN         */ TCP_CLOSE,
1840  /* TCP_CLOSING        */ TCP_CLOSING,
1841};
1842
1843static int tcp_close_state(struct sock *sk)
1844{
1845        int next = (int)new_state[sk->sk_state];
1846        int ns = next & TCP_STATE_MASK;
1847
1848        tcp_set_state(sk, ns);
1849
1850        return next & TCP_ACTION_FIN;
1851}
1852
1853/*
1854 *      Shutdown the sending side of a connection. Much like close except
1855 *      that we don't receive shut down or sock_set_flag(sk, SOCK_DEAD).
1856 */
1857
1858void tcp_shutdown(struct sock *sk, int how)
1859{
1860        /*      We need to grab some memory, and put together a FIN,
1861         *      and then put it into the queue to be sent.
1862         *              Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
1863         */
1864        if (!(how & SEND_SHUTDOWN))
1865                return;
1866
1867        /* If we've already sent a FIN, or it's a closed state, skip this. */
1868        if ((1 << sk->sk_state) &
1869            (TCPF_ESTABLISHED | TCPF_SYN_SENT |
1870             TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
1871                /* Clear out any half completed packets.  FIN if needed. */
1872                if (tcp_close_state(sk))
1873                        tcp_send_fin(sk);
1874        }
1875}
1876EXPORT_SYMBOL(tcp_shutdown);
1877
1878void tcp_close(struct sock *sk, long timeout)
1879{
1880        struct sk_buff *skb;
1881        int data_was_unread = 0;
1882        int state;
1883
1884        lock_sock(sk);
1885        sk->sk_shutdown = SHUTDOWN_MASK;
1886
1887        if (sk->sk_state == TCP_LISTEN) {
1888                tcp_set_state(sk, TCP_CLOSE);
1889
1890                /* Special case. */
1891                inet_csk_listen_stop(sk);
1892
1893                goto adjudge_to_death;
1894        }
1895
1896        /*  We need to flush the recv. buffs.  We do this only on the
1897         *  descriptor close, not protocol-sourced closes, because the
1898         *  reader process may not have drained the data yet!
1899         */
1900        while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
1901                u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq -
1902                          tcp_hdr(skb)->fin;
1903                data_was_unread += len;
1904                __kfree_skb(skb);
1905        }
1906
1907        sk_mem_reclaim(sk);
1908
1909        /* If socket has been already reset (e.g. in tcp_reset()) - kill it. */
1910        if (sk->sk_state == TCP_CLOSE)
1911                goto adjudge_to_death;
1912
1913        /* As outlined in RFC 2525, section 2.17, we send a RST here because
1914         * data was lost. To witness the awful effects of the old behavior of
1915         * always doing a FIN, run an older 2.1.x kernel or 2.0.x, start a bulk
1916         * GET in an FTP client, suspend the process, wait for the client to
1917         * advertise a zero window, then kill -9 the FTP client, wheee...
1918         * Note: timeout is always zero in such a case.
1919         */
1920        if (data_was_unread) {
1921                /* Unread data was tossed, zap the connection. */
1922                NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPABORTONCLOSE);
1923                tcp_set_state(sk, TCP_CLOSE);
1924                tcp_send_active_reset(sk, sk->sk_allocation);
1925        } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
1926                /* Check zero linger _after_ checking for unread data. */
1927                sk->sk_prot->disconnect(sk, 0);
1928                NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
1929        } else if (tcp_close_state(sk)) {
1930                /* We FIN if the application ate all the data before
1931                 * zapping the connection.
1932                 */
1933
1934                /* RED-PEN. Formally speaking, we have broken TCP state
1935                 * machine. State transitions:
1936                 *
1937                 * TCP_ESTABLISHED -> TCP_FIN_WAIT1
1938                 * TCP_SYN_RECV -> TCP_FIN_WAIT1 (forget it, it's impossible)
1939                 * TCP_CLOSE_WAIT -> TCP_LAST_ACK
1940                 *
1941                 * are legal only when FIN has been sent (i.e. in window),
1942                 * rather than queued out of window. Purists blame.
1943                 *
1944                 * F.e. "RFC state" is ESTABLISHED,
1945                 * if Linux state is FIN-WAIT-1, but FIN is still not sent.
1946                 *
1947                 * The visible declinations are that sometimes
1948                 * we enter time-wait state, when it is not required really
1949                 * (harmless), do not send active resets, when they are
1950                 * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when
1951                 * they look as CLOSING or LAST_ACK for Linux)
1952                 * Probably, I missed some more holelets.
1953                 *                                              --ANK
1954                 */
1955                tcp_send_fin(sk);
1956        }
1957
1958        sk_stream_wait_close(sk, timeout);
1959
1960adjudge_to_death:
1961        state = sk->sk_state;
1962        sock_hold(sk);
1963        sock_orphan(sk);
1964
1965        /* It is the last release_sock in its life. It will remove backlog. */
1966        release_sock(sk);
1967
1968
1969        /* Now socket is owned by kernel and we acquire BH lock
1970           to finish close. No need to check for user refs.
1971         */
1972        local_bh_disable();
1973        bh_lock_sock(sk);
1974        WARN_ON(sock_owned_by_user(sk));
1975
1976        percpu_counter_inc(sk->sk_prot->orphan_count);
1977
1978        /* Have we already been destroyed by a softirq or backlog? */
1979        if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
1980                goto out;
1981
1982        /*      This is a (useful) BSD violating of the RFC. There is a
1983         *      problem with TCP as specified in that the other end could
1984         *      keep a socket open forever with no application left this end.
1985         *      We use a 3 minute timeout (about the same as BSD) then kill
1986         *      our end. If they send after that then tough - BUT: long enough
1987         *      that we won't make the old 4*rto = almost no time - whoops
1988         *      reset mistake.
1989         *
1990         *      Nope, it was not mistake. It is really desired behaviour
1991         *      f.e. on http servers, when such sockets are useless, but
1992         *      consume significant resources. Let's do it with special
1993         *      linger2 option.                                 --ANK
1994         */
1995
1996        if (sk->sk_state == TCP_FIN_WAIT2) {
1997                struct tcp_sock *tp = tcp_sk(sk);
1998                if (tp->linger2 < 0) {
1999                        tcp_set_state(sk, TCP_CLOSE);
2000                        tcp_send_active_reset(sk, GFP_ATOMIC);
2001                        NET_INC_STATS_BH(sock_net(sk),
2002                                        LINUX_MIB_TCPABORTONLINGER);
2003                } else {
2004                        const int tmo = tcp_fin_time(sk);
2005
2006                        if (tmo > TCP_TIMEWAIT_LEN) {
2007                                inet_csk_reset_keepalive_timer(sk,
2008                                                tmo - TCP_TIMEWAIT_LEN);
2009                        } else {
2010                                tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
2011                                goto out;
2012                        }
2013                }
2014        }
2015        if (sk->sk_state != TCP_CLOSE) {
2016                sk_mem_reclaim(sk);
2017                if (tcp_too_many_orphans(sk, 0)) {
2018                        if (net_ratelimit())
2019                                printk(KERN_INFO "TCP: too many of orphaned "
2020                                       "sockets\n");
2021                        tcp_set_state(sk, TCP_CLOSE);
2022                        tcp_send_active_reset(sk, GFP_ATOMIC);
2023                        NET_INC_STATS_BH(sock_net(sk),
2024                                        LINUX_MIB_TCPABORTONMEMORY);
2025                }
2026        }
2027
2028        if (sk->sk_state == TCP_CLOSE)
2029                inet_csk_destroy_sock(sk);
2030        /* Otherwise, socket is reprieved until protocol close. */
2031
2032out:
2033        bh_unlock_sock(sk);
2034        local_bh_enable();
2035        sock_put(sk);
2036}
2037EXPORT_SYMBOL(tcp_close);
2038
2039/* These states need RST on ABORT according to RFC793 */
2040
2041static inline int tcp_need_reset(int state)
2042{
2043        return (1 << state) &
2044               (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
2045                TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
2046}
2047
2048int tcp_disconnect(struct sock *sk, int flags)
2049{
2050        struct inet_sock *inet = inet_sk(sk);
2051        struct inet_connection_sock *icsk = inet_csk(sk);
2052        struct tcp_sock *tp = tcp_sk(sk);
2053        int err = 0;
2054        int old_state = sk->sk_state;
2055
2056        if (old_state != TCP_CLOSE)
2057                tcp_set_state(sk, TCP_CLOSE);
2058
2059        /* ABORT function of RFC793 */
2060        if (old_state == TCP_LISTEN) {
2061                inet_csk_listen_stop(sk);
2062        } else if (tcp_need_reset(old_state) ||
2063                   (tp->snd_nxt != tp->write_seq &&
2064                    (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
2065                /* The last check adjusts for discrepancy of Linux wrt. RFC
2066                 * states
2067                 */
2068                tcp_send_active_reset(sk, gfp_any());
2069                sk->sk_err = ECONNRESET;
2070        } else if (old_state == TCP_SYN_SENT)
2071                sk->sk_err = ECONNRESET;
2072
2073        tcp_clear_xmit_timers(sk);
2074        __skb_queue_purge(&sk->sk_receive_queue);
2075        tcp_write_queue_purge(sk);
2076        __skb_queue_purge(&tp->out_of_order_queue);
2077#ifdef CONFIG_NET_DMA
2078        __skb_queue_purge(&sk->sk_async_wait_queue);
2079#endif
2080
2081        inet->inet_dport = 0;
2082
2083        if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
2084                inet_reset_saddr(sk);
2085
2086        sk->sk_shutdown = 0;
2087        sock_reset_flag(sk, SOCK_DONE);
2088        tp->srtt = 0;
2089        if ((tp->write_seq += tp->max_window + 2) == 0)
2090                tp->write_seq = 1;
2091        icsk->icsk_backoff = 0;
2092        tp->snd_cwnd = 2;
2093        icsk->icsk_probes_out = 0;
2094        tp->packets_out = 0;
2095        tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
2096        tp->snd_cwnd_cnt = 0;
2097        tp->bytes_acked = 0;
2098        tp->window_clamp = 0;
2099        tcp_set_ca_state(sk, TCP_CA_Open);
2100        tcp_clear_retrans(tp);
2101        inet_csk_delack_init(sk);
2102        tcp_init_send_head(sk);
2103        memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
2104        __sk_dst_reset(sk);
2105
2106        WARN_ON(inet->inet_num && !icsk->icsk_bind_hash);
2107
2108        sk->sk_error_report(sk);
2109        return err;
2110}
2111EXPORT_SYMBOL(tcp_disconnect);
2112
2113/*
2114 *      Socket option code for TCP.
2115 */
2116static int do_tcp_setsockopt(struct sock *sk, int level,
2117                int optname, char __user *optval, unsigned int optlen)
2118{
2119        struct tcp_sock *tp = tcp_sk(sk);
2120        struct inet_connection_sock *icsk = inet_csk(sk);
2121        int val;
2122        int err = 0;
2123
2124        /* These are data/string values, all the others are ints */
2125        switch (optname) {
2126        case TCP_CONGESTION: {
2127                char name[TCP_CA_NAME_MAX];
2128
2129                if (optlen < 1)
2130                        return -EINVAL;
2131
2132                val = strncpy_from_user(name, optval,
2133                                        min_t(long, TCP_CA_NAME_MAX-1, optlen));
2134                if (val < 0)
2135                        return -EFAULT;
2136                name[val] = 0;
2137
2138                lock_sock(sk);
2139                err = tcp_set_congestion_control(sk, name);
2140                release_sock(sk);
2141                return err;
2142        }
2143        case TCP_COOKIE_TRANSACTIONS: {
2144                struct tcp_cookie_transactions ctd;
2145                struct tcp_cookie_values *cvp = NULL;
2146
2147                if (sizeof(ctd) > optlen)
2148                        return -EINVAL;
2149                if (copy_from_user(&ctd, optval, sizeof(ctd)))
2150                        return -EFAULT;
2151
2152                if (ctd.tcpct_used > sizeof(ctd.tcpct_value) ||
2153                    ctd.tcpct_s_data_desired > TCP_MSS_DESIRED)
2154                        return -EINVAL;
2155
2156                if (ctd.tcpct_cookie_desired == 0) {
2157                        /* default to global value */
2158                } else if ((0x1 & ctd.tcpct_cookie_desired) ||
2159                           ctd.tcpct_cookie_desired > TCP_COOKIE_MAX ||
2160                           ctd.tcpct_cookie_desired < TCP_COOKIE_MIN) {
2161                        return -EINVAL;
2162                }
2163
2164                if (TCP_COOKIE_OUT_NEVER & ctd.tcpct_flags) {
2165                        /* Supercedes all other values */
2166                        lock_sock(sk);
2167                        if (tp->cookie_values != NULL) {
2168                                kref_put(&tp->cookie_values->kref,
2169                                         tcp_cookie_values_release);
2170                                tp->cookie_values = NULL;
2171                        }
2172                        tp->rx_opt.cookie_in_always = 0; /* false */
2173                        tp->rx_opt.cookie_out_never = 1; /* true */
2174                        release_sock(sk);
2175                        return err;
2176                }
2177
2178                /* Allocate ancillary memory before locking.
2179                 */
2180                if (ctd.tcpct_used > 0 ||
2181                    (tp->cookie_values == NULL &&
2182                     (sysctl_tcp_cookie_size > 0 ||
2183                      ctd.tcpct_cookie_desired > 0 ||
2184                      ctd.tcpct_s_data_desired > 0))) {
2185                        cvp = kzalloc(sizeof(*cvp) + ctd.tcpct_used,
2186                                      GFP_KERNEL);
2187                        if (cvp == NULL)
2188                                return -ENOMEM;
2189
2190                        kref_init(&cvp->kref);
2191                }
2192                lock_sock(sk);
2193                tp->rx_opt.cookie_in_always =
2194                        (TCP_COOKIE_IN_ALWAYS & ctd.tcpct_flags);
2195                tp->rx_opt.cookie_out_never = 0; /* false */
2196
2197                if (tp->cookie_values != NULL) {
2198                        if (cvp != NULL) {
2199                                /* Changed values are recorded by a changed
2200                                 * pointer, ensuring the cookie will differ,
2201                                 * without separately hashing each value later.
2202                                 */
2203                                kref_put(&tp->cookie_values->kref,
2204                                         tcp_cookie_values_release);
2205                        } else {
2206                                cvp = tp->cookie_values;
2207                        }
2208                }
2209
2210                if (cvp != NULL) {
2211                        cvp->cookie_desired = ctd.tcpct_cookie_desired;
2212
2213                        if (ctd.tcpct_used > 0) {
2214                                memcpy(cvp->s_data_payload, ctd.tcpct_value,
2215                                       ctd.tcpct_used);
2216                                cvp->s_data_desired = ctd.tcpct_used;
2217                                cvp->s_data_constant = 1; /* true */
2218                        } else {
2219                                /* No constant payload data. */
2220                                cvp->s_data_desired = ctd.tcpct_s_data_desired;
2221                                cvp->s_data_constant = 0; /* false */
2222                        }
2223
2224                        tp->cookie_values = cvp;
2225                }
2226                release_sock(sk);
2227                return err;
2228        }
2229        default:
2230                /* fallthru */
2231                break;
2232        }
2233
2234        if (optlen < sizeof(int))
2235                return -EINVAL;
2236
2237        if (get_user(val, (int __user *)optval))
2238                return -EFAULT;
2239
2240        lock_sock(sk);
2241
2242        switch (optname) {
2243        case TCP_MAXSEG:
2244                /* Values greater than interface MTU won't take effect. However
2245                 * at the point when this call is done we typically don't yet
2246                 * know which interface is going to be used */
2247                if (val < TCP_MIN_MSS || val > MAX_TCP_WINDOW) {
2248                        err = -EINVAL;
2249                        break;
2250                }
2251                tp->rx_opt.user_mss = val;
2252                break;
2253
2254        case TCP_NODELAY:
2255                if (val) {
2256                        /* TCP_NODELAY is weaker than TCP_CORK, so that
2257                         * this option on corked socket is remembered, but
2258                         * it is not activated until cork is cleared.
2259                         *
2260                         * However, when TCP_NODELAY is set we make
2261                         * an explicit push, which overrides even TCP_CORK
2262                         * for currently queued segments.
2263                         */
2264                        tp->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
2265                        tcp_push_pending_frames(sk);
2266                } else {
2267                        tp->nonagle &= ~TCP_NAGLE_OFF;
2268                }
2269                break;
2270
2271        case TCP_THIN_LINEAR_TIMEOUTS:
2272                if (val < 0 || val > 1)
2273                        err = -EINVAL;
2274                else
2275                        tp->thin_lto = val;
2276                break;
2277
2278        case TCP_THIN_DUPACK:
2279                if (val < 0 || val > 1)
2280                        err = -EINVAL;
2281                else
2282                        tp->thin_dupack = val;
2283                break;
2284
2285        case TCP_CORK:
2286                /* When set indicates to always queue non-full frames.
2287                 * Later the user clears this option and we transmit
2288                 * any pending partial frames in the queue.  This is
2289                 * meant to be used alongside sendfile() to get properly
2290                 * filled frames when the user (for example) must write
2291                 * out headers with a write() call first and then use
2292                 * sendfile to send out the data parts.
2293                 *
2294                 * TCP_CORK can be set together with TCP_NODELAY and it is
2295                 * stronger than TCP_NODELAY.
2296                 */
2297                if (val) {
2298                        tp->nonagle |= TCP_NAGLE_CORK;
2299                } else {
2300                        tp->nonagle &= ~TCP_NAGLE_CORK;
2301                        if (tp->nonagle&TCP_NAGLE_OFF)
2302                                tp->nonagle |= TCP_NAGLE_PUSH;
2303                        tcp_push_pending_frames(sk);
2304                }
2305                break;
2306
2307        case TCP_KEEPIDLE:
2308                if (val < 1 || val > MAX_TCP_KEEPIDLE)
2309                        err = -EINVAL;
2310                else {
2311                        tp->keepalive_time = val * HZ;
2312                        if (sock_flag(sk, SOCK_KEEPOPEN) &&
2313                            !((1 << sk->sk_state) &
2314                              (TCPF_CLOSE | TCPF_LISTEN))) {
2315                                u32 elapsed = keepalive_time_elapsed(tp);
2316                                if (tp->keepalive_time > elapsed)
2317                                        elapsed = tp->keepalive_time - elapsed;
2318                                else
2319                                        elapsed = 0;
2320                                inet_csk_reset_keepalive_timer(sk, elapsed);
2321                        }
2322                }
2323                break;
2324        case TCP_KEEPINTVL:
2325                if (val < 1 || val > MAX_TCP_KEEPINTVL)
2326                        err = -EINVAL;
2327                else
2328                        tp->keepalive_intvl = val * HZ;
2329                break;
2330        case TCP_KEEPCNT:
2331                if (val < 1 || val > MAX_TCP_KEEPCNT)
2332                        err = -EINVAL;
2333                else
2334                        tp->keepalive_probes = val;
2335                break;
2336        case TCP_SYNCNT:
2337                if (val < 1 || val > MAX_TCP_SYNCNT)
2338                        err = -EINVAL;
2339                else
2340                        icsk->icsk_syn_retries = val;
2341                break;
2342
2343        case TCP_LINGER2:
2344                if (val < 0)
2345                        tp->linger2 = -1;
2346                else if (val > sysctl_tcp_fin_timeout / HZ)
2347                        tp->linger2 = 0;
2348                else
2349                        tp->linger2 = val * HZ;
2350                break;
2351
2352        case TCP_DEFER_ACCEPT:
2353                /* Translate value in seconds to number of retransmits */
2354                icsk->icsk_accept_queue.rskq_defer_accept =
2355                        secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,
2356                                        TCP_RTO_MAX / HZ);
2357                break;
2358
2359        case TCP_WINDOW_CLAMP:
2360                if (!val) {
2361                        if (sk->sk_state != TCP_CLOSE) {
2362                                err = -EINVAL;
2363                                break;
2364                        }
2365                        tp->window_clamp = 0;
2366                } else
2367                        tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
2368                                                SOCK_MIN_RCVBUF / 2 : val;
2369                break;
2370
2371        case TCP_QUICKACK:
2372                if (!val) {
2373                        icsk->icsk_ack.pingpong = 1;
2374                } else {
2375                        icsk->icsk_ack.pingpong = 0;
2376                        if ((1 << sk->sk_state) &
2377                            (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
2378                            inet_csk_ack_scheduled(sk)) {
2379                                icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
2380                                tcp_cleanup_rbuf(sk, 1);
2381                                if (!(val & 1))
2382                                        icsk->icsk_ack.pingpong = 1;
2383                        }
2384                }
2385                break;
2386
2387#ifdef CONFIG_TCP_MD5SIG
2388        case TCP_MD5SIG:
2389                /* Read the IP->Key mappings from userspace */
2390                err = tp->af_specific->md5_parse(sk, optval, optlen);
2391                break;
2392#endif
2393        case TCP_USER_TIMEOUT:
2394                /* Cap the max timeout in ms TCP will retry/retrans
2395                 * before giving up and aborting (ETIMEDOUT) a connection.
2396                 */
2397                icsk->icsk_user_timeout = msecs_to_jiffies(val);
2398                break;
2399        default:
2400                err = -ENOPROTOOPT;
2401                break;
2402        }
2403
2404        release_sock(sk);
2405        return err;
2406}
2407
2408int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
2409                   unsigned int optlen)
2410{
2411        struct inet_connection_sock *icsk = inet_csk(sk);
2412
2413        if (level != SOL_TCP)
2414                return icsk->icsk_af_ops->setsockopt(sk, level, optname,
2415                                                     optval, optlen);
2416        return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2417}
2418EXPORT_SYMBOL(tcp_setsockopt);
2419
2420#ifdef CONFIG_COMPAT
2421int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
2422                          char __user *optval, unsigned int optlen)
2423{
2424        if (level != SOL_TCP)
2425                return inet_csk_compat_setsockopt(sk, level, optname,
2426                                                  optval, optlen);
2427        return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2428}
2429EXPORT_SYMBOL(compat_tcp_setsockopt);
2430#endif
2431
2432/* Return information about state of tcp endpoint in API format. */
2433void tcp_get_info(struct sock *sk, struct tcp_info *info)
2434{
2435        struct tcp_sock *tp = tcp_sk(sk);
2436        const struct inet_connection_sock *icsk = inet_csk(sk);
2437        u32 now = tcp_time_stamp;
2438
2439        memset(info, 0, sizeof(*info));
2440
2441        info->tcpi_state = sk->sk_state;
2442        info->tcpi_ca_state = icsk->icsk_ca_state;
2443        info->tcpi_retransmits = icsk->icsk_retransmits;
2444        info->tcpi_probes = icsk->icsk_probes_out;
2445        info->tcpi_backoff = icsk->icsk_backoff;
2446
2447        if (tp->rx_opt.tstamp_ok)
2448                info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
2449        if (tcp_is_sack(tp))
2450                info->tcpi_options |= TCPI_OPT_SACK;
2451        if (tp->rx_opt.wscale_ok) {
2452                info->tcpi_options |= TCPI_OPT_WSCALE;
2453                info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
2454                info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
2455        }
2456
2457        if (tp->ecn_flags&TCP_ECN_OK)
2458                info->tcpi_options |= TCPI_OPT_ECN;
2459
2460        info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
2461        info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
2462        info->tcpi_snd_mss = tp->mss_cache;
2463        info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
2464
2465        if (sk->sk_state == TCP_LISTEN) {
2466                info->tcpi_unacked = sk->sk_ack_backlog;
2467                info->tcpi_sacked = sk->sk_max_ack_backlog;
2468        } else {
2469                info->tcpi_unacked = tp->packets_out;
2470                info->tcpi_sacked = tp->sacked_out;
2471        }
2472        info->tcpi_lost = tp->lost_out;
2473        info->tcpi_retrans = tp->retrans_out;
2474        info->tcpi_fackets = tp->fackets_out;
2475
2476        info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
2477        info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
2478        info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
2479
2480        info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
2481        info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
2482        info->tcpi_rtt = jiffies_to_usecs(tp->srtt)>>3;
2483        info->tcpi_rttvar = jiffies_to_usecs(tp->mdev)>>2;
2484        info->tcpi_snd_ssthresh = tp->snd_ssthresh;
2485        info->tcpi_snd_cwnd = tp->snd_cwnd;
2486        info->tcpi_advmss = tp->advmss;
2487        info->tcpi_reordering = tp->reordering;
2488
2489        info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3;
2490        info->tcpi_rcv_space = tp->rcvq_space.space;
2491
2492        info->tcpi_total_retrans = tp->total_retrans;
2493}
2494EXPORT_SYMBOL_GPL(tcp_get_info);
2495
2496static int do_tcp_getsockopt(struct sock *sk, int level,
2497                int optname, char __user *optval, int __user *optlen)
2498{
2499        struct inet_connection_sock *icsk = inet_csk(sk);
2500        struct tcp_sock *tp = tcp_sk(sk);
2501        int val, len;
2502
2503        if (get_user(len, optlen))
2504                return -EFAULT;
2505
2506        len = min_t(unsigned int, len, sizeof(int));
2507
2508        if (len < 0)
2509                return -EINVAL;
2510
2511        switch (optname) {
2512        case TCP_MAXSEG:
2513                val = tp->mss_cache;
2514                if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
2515                        val = tp->rx_opt.user_mss;
2516                break;
2517        case TCP_NODELAY:
2518                val = !!(tp->nonagle&TCP_NAGLE_OFF);
2519                break;
2520        case TCP_CORK:
2521                val = !!(tp->nonagle&TCP_NAGLE_CORK);
2522                break;
2523        case TCP_KEEPIDLE:
2524                val = keepalive_time_when(tp) / HZ;
2525                break;
2526        case TCP_KEEPINTVL:
2527                val = keepalive_intvl_when(tp) / HZ;
2528                break;
2529        case TCP_KEEPCNT:
2530                val = keepalive_probes(tp);
2531                break;
2532        case TCP_SYNCNT:
2533                val = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
2534                break;
2535        case TCP_LINGER2:
2536                val = tp->linger2;
2537                if (val >= 0)
2538                        val = (val ? : sysctl_tcp_fin_timeout) / HZ;
2539                break;
2540        case TCP_DEFER_ACCEPT:
2541                val = retrans_to_secs(icsk->icsk_accept_queue.rskq_defer_accept,
2542                                      TCP_TIMEOUT_INIT / HZ, TCP_RTO_MAX / HZ);
2543                break;
2544        case TCP_WINDOW_CLAMP:
2545                val = tp->window_clamp;
2546                break;
2547        case TCP_INFO: {
2548                struct tcp_info info;
2549
2550                if (get_user(len, optlen))
2551                        return -EFAULT;
2552
2553                tcp_get_info(sk, &info);
2554
2555                len = min_t(unsigned int, len, sizeof(info));
2556                if (put_user(len, optlen))
2557                        return -EFAULT;
2558                if (copy_to_user(optval, &info, len))
2559                        return -EFAULT;
2560                return 0;
2561        }
2562        case TCP_QUICKACK:
2563                val = !icsk->icsk_ack.pingpong;
2564                break;
2565
2566        case TCP_CONGESTION:
2567                if (get_user(len, optlen))
2568                        return -EFAULT;
2569                len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
2570                if (put_user(len, optlen))
2571                        return -EFAULT;
2572                if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
2573                        return -EFAULT;
2574                return 0;
2575
2576        case TCP_COOKIE_TRANSACTIONS: {
2577                struct tcp_cookie_transactions ctd;
2578                struct tcp_cookie_values *cvp = tp->cookie_values;
2579
2580                if (get_user(len, optlen))
2581                        return -EFAULT;
2582                if (len < sizeof(ctd))
2583                        return -EINVAL;
2584
2585                memset(&ctd, 0, sizeof(ctd));
2586                ctd.tcpct_flags = (tp->rx_opt.cookie_in_always ?
2587                                   TCP_COOKIE_IN_ALWAYS : 0)
2588                                | (tp->rx_opt.cookie_out_never ?
2589                                   TCP_COOKIE_OUT_NEVER : 0);
2590
2591                if (cvp != NULL) {
2592                        ctd.tcpct_flags |= (cvp->s_data_in ?
2593                                            TCP_S_DATA_IN : 0)
2594                                         | (cvp->s_data_out ?
2595                                            TCP_S_DATA_OUT : 0);
2596
2597                        ctd.tcpct_cookie_desired = cvp->cookie_desired;
2598                        ctd.tcpct_s_data_desired = cvp->s_data_desired;
2599
2600                        memcpy(&ctd.tcpct_value[0], &cvp->cookie_pair[0],
2601                               cvp->cookie_pair_size);
2602                        ctd.tcpct_used = cvp->cookie_pair_size;
2603                }
2604
2605                if (put_user(sizeof(ctd), optlen))
2606                        return -EFAULT;
2607                if (copy_to_user(optval, &ctd, sizeof(ctd)))
2608                        return -EFAULT;
2609                return 0;
2610        }
2611        case TCP_THIN_LINEAR_TIMEOUTS:
2612                val = tp->thin_lto;
2613                break;
2614        case TCP_THIN_DUPACK:
2615                val = tp->thin_dupack;
2616                break;
2617
2618        case TCP_USER_TIMEOUT:
2619                val = jiffies_to_msecs(icsk->icsk_user_timeout);
2620                break;
2621        default:
2622                return -ENOPROTOOPT;
2623        }
2624
2625        if (put_user(len, optlen))
2626                return -EFAULT;
2627        if (copy_to_user(optval, &val, len))
2628                return -EFAULT;
2629        return 0;
2630}
2631
2632int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
2633                   int __user *optlen)
2634{
2635        struct inet_connection_sock *icsk = inet_csk(sk);
2636
2637        if (level != SOL_TCP)
2638                return icsk->icsk_af_ops->getsockopt(sk, level, optname,
2639                                                     optval, optlen);
2640        return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2641}
2642EXPORT_SYMBOL(tcp_getsockopt);
2643
2644#ifdef CONFIG_COMPAT
2645int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
2646                          char __user *optval, int __user *optlen)
2647{
2648        if (level != SOL_TCP)
2649                return inet_csk_compat_getsockopt(sk, level, optname,
2650                                                  optval, optlen);
2651        return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2652}
2653EXPORT_SYMBOL(compat_tcp_getsockopt);
2654#endif
2655
2656struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int features)
2657{
2658        struct sk_buff *segs = ERR_PTR(-EINVAL);
2659        struct tcphdr *th;
2660        unsigned thlen;
2661        unsigned int seq;
2662        __be32 delta;
2663        unsigned int oldlen;
2664        unsigned int mss;
2665
2666        if (!pskb_may_pull(skb, sizeof(*th)))
2667                goto out;
2668
2669        th = tcp_hdr(skb);
2670        thlen = th->doff * 4;
2671        if (thlen < sizeof(*th))
2672                goto out;
2673
2674        if (!pskb_may_pull(skb, thlen))
2675                goto out;
2676
2677        oldlen = (u16)~skb->len;
2678        __skb_pull(skb, thlen);
2679
2680        mss = skb_shinfo(skb)->gso_size;
2681        if (unlikely(skb->len <= mss))
2682                goto out;
2683
2684        if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
2685                /* Packet is from an untrusted source, reset gso_segs. */
2686                int type = skb_shinfo(skb)->gso_type;
2687
2688                if (unlikely(type &
2689                             ~(SKB_GSO_TCPV4 |
2690                               SKB_GSO_DODGY |
2691                               SKB_GSO_TCP_ECN |
2692                               SKB_GSO_TCPV6 |
2693                               0) ||
2694                             !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))))
2695                        goto out;
2696
2697                skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
2698
2699                segs = NULL;
2700                goto out;
2701        }
2702
2703        segs = skb_segment(skb, features);
2704        if (IS_ERR(segs))
2705                goto out;
2706
2707        delta = htonl(oldlen + (thlen + mss));
2708
2709        skb = segs;
2710        th = tcp_hdr(skb);
2711        seq = ntohl(th->seq);
2712
2713        do {
2714                th->fin = th->psh = 0;
2715
2716                th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
2717                                       (__force u32)delta));
2718                if (skb->ip_summed != CHECKSUM_PARTIAL)
2719                        th->check =
2720                             csum_fold(csum_partial(skb_transport_header(skb),
2721                                                    thlen, skb->csum));
2722
2723                seq += mss;
2724                skb = skb->next;
2725                th = tcp_hdr(skb);
2726
2727                th->seq = htonl(seq);
2728                th->cwr = 0;
2729        } while (skb->next);
2730
2731        delta = htonl(oldlen + (skb->tail - skb->transport_header) +
2732                      skb->data_len);
2733        th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
2734                                (__force u32)delta));
2735        if (skb->ip_summed != CHECKSUM_PARTIAL)
2736                th->check = csum_fold(csum_partial(skb_transport_header(skb),
2737                                                   thlen, skb->csum));
2738
2739out:
2740        return segs;
2741}
2742EXPORT_SYMBOL(tcp_tso_segment);
2743
2744struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
2745{
2746        struct sk_buff **pp = NULL;
2747        struct sk_buff *p;
2748        struct tcphdr *th;
2749        struct tcphdr *th2;
2750        unsigned int len;
2751        unsigned int thlen;
2752        __be32 flags;
2753        unsigned int mss = 1;
2754        unsigned int hlen;
2755        unsigned int off;
2756        int flush = 1;
2757        int i;
2758
2759        off = skb_gro_offset(skb);
2760        hlen = off + sizeof(*th);
2761        th = skb_gro_header_fast(skb, off);
2762        if (skb_gro_header_hard(skb, hlen)) {
2763                th = skb_gro_header_slow(skb, hlen, off);
2764                if (unlikely(!th))
2765                        goto out;
2766        }
2767
2768        thlen = th->doff * 4;
2769        if (thlen < sizeof(*th))
2770                goto out;
2771
2772        hlen = off + thlen;
2773        if (skb_gro_header_hard(skb, hlen)) {
2774                th = skb_gro_header_slow(skb, hlen, off);
2775                if (unlikely(!th))
2776                        goto out;
2777        }
2778
2779        skb_gro_pull(skb, thlen);
2780
2781        len = skb_gro_len(skb);
2782        flags = tcp_flag_word(th);
2783
2784        for (; (p = *head); head = &p->next) {
2785                if (!NAPI_GRO_CB(p)->same_flow)
2786                        continue;
2787
2788                th2 = tcp_hdr(p);
2789
2790                if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
2791                        NAPI_GRO_CB(p)->same_flow = 0;
2792                        continue;
2793                }
2794
2795                goto found;
2796        }
2797
2798        goto out_check_final;
2799
2800found:
2801        flush = NAPI_GRO_CB(p)->flush;
2802        flush |= (__force int)(flags & TCP_FLAG_CWR);
2803        flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
2804                  ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
2805        flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
2806        for (i = sizeof(*th); i < thlen; i += 4)
2807                flush |= *(u32 *)((u8 *)th + i) ^
2808                         *(u32 *)((u8 *)th2 + i);
2809
2810        mss = skb_shinfo(p)->gso_size;
2811
2812        flush |= (len - 1) >= mss;
2813        flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
2814
2815        if (flush || skb_gro_receive(head, skb)) {
2816                mss = 1;
2817                goto out_check_final;
2818        }
2819
2820        p = *head;
2821        th2 = tcp_hdr(p);
2822        tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);
2823
2824out_check_final:
2825        flush = len < mss;
2826        flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH |
2827                                        TCP_FLAG_RST | TCP_FLAG_SYN |
2828                                        TCP_FLAG_FIN));
2829
2830        if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
2831                pp = head;
2832
2833out:
2834        NAPI_GRO_CB(skb)->flush |= flush;
2835
2836        return pp;
2837}
2838EXPORT_SYMBOL(tcp_gro_receive);
2839
2840int tcp_gro_complete(struct sk_buff *skb)
2841{
2842        struct tcphdr *th = tcp_hdr(skb);
2843
2844        skb->csum_start = skb_transport_header(skb) - skb->head;
2845        skb->csum_offset = offsetof(struct tcphdr, check);
2846        skb->ip_summed = CHECKSUM_PARTIAL;
2847
2848        skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
2849
2850        if (th->cwr)
2851                skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
2852
2853        return 0;
2854}
2855EXPORT_SYMBOL(tcp_gro_complete);
2856
2857#ifdef CONFIG_TCP_MD5SIG
2858static unsigned long tcp_md5sig_users;
2859static struct tcp_md5sig_pool * __percpu *tcp_md5sig_pool;
2860static DEFINE_SPINLOCK(tcp_md5sig_pool_lock);
2861
2862static void __tcp_free_md5sig_pool(struct tcp_md5sig_pool * __percpu *pool)
2863{
2864        int cpu;
2865        for_each_possible_cpu(cpu) {
2866                struct tcp_md5sig_pool *p = *per_cpu_ptr(pool, cpu);
2867                if (p) {
2868                        if (p->md5_desc.tfm)
2869                                crypto_free_hash(p->md5_desc.tfm);
2870                        kfree(p);
2871                }
2872        }
2873        free_percpu(pool);
2874}
2875
2876void tcp_free_md5sig_pool(void)
2877{
2878        struct tcp_md5sig_pool * __percpu *pool = NULL;
2879
2880        spin_lock_bh(&tcp_md5sig_pool_lock);
2881        if (--tcp_md5sig_users == 0) {
2882                pool = tcp_md5sig_pool;
2883                tcp_md5sig_pool = NULL;
2884        }
2885        spin_unlock_bh(&tcp_md5sig_pool_lock);
2886        if (pool)
2887                __tcp_free_md5sig_pool(pool);
2888}
2889EXPORT_SYMBOL(tcp_free_md5sig_pool);
2890
2891static struct tcp_md5sig_pool * __percpu *
2892__tcp_alloc_md5sig_pool(struct sock *sk)
2893{
2894        int cpu;
2895        struct tcp_md5sig_pool * __percpu *pool;
2896
2897        pool = alloc_percpu(struct tcp_md5sig_pool *);
2898        if (!pool)
2899                return NULL;
2900
2901        for_each_possible_cpu(cpu) {
2902                struct tcp_md5sig_pool *p;
2903                struct crypto_hash *hash;
2904
2905                p = kzalloc(sizeof(*p), sk->sk_allocation);
2906                if (!p)
2907                        goto out_free;
2908                *per_cpu_ptr(pool, cpu) = p;
2909
2910                hash = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
2911                if (!hash || IS_ERR(hash))
2912                        goto out_free;
2913
2914                p->md5_desc.tfm = hash;
2915        }
2916        return pool;
2917out_free:
2918        __tcp_free_md5sig_pool(pool);
2919        return NULL;
2920}
2921
2922struct tcp_md5sig_pool * __percpu *tcp_alloc_md5sig_pool(struct sock *sk)
2923{
2924        struct tcp_md5sig_pool * __percpu *pool;
2925        int alloc = 0;
2926
2927retry:
2928        spin_lock_bh(&tcp_md5sig_pool_lock);
2929        pool = tcp_md5sig_pool;
2930        if (tcp_md5sig_users++ == 0) {
2931                alloc = 1;
2932                spin_unlock_bh(&tcp_md5sig_pool_lock);
2933        } else if (!pool) {
2934                tcp_md5sig_users--;
2935                spin_unlock_bh(&tcp_md5sig_pool_lock);
2936                cpu_relax();
2937                goto retry;
2938        } else
2939                spin_unlock_bh(&tcp_md5sig_pool_lock);
2940
2941        if (alloc) {
2942                /* we cannot hold spinlock here because this may sleep. */
2943                struct tcp_md5sig_pool * __percpu *p;
2944
2945                p = __tcp_alloc_md5sig_pool(sk);
2946                spin_lock_bh(&tcp_md5sig_pool_lock);
2947                if (!p) {
2948                        tcp_md5sig_users--;
2949                        spin_unlock_bh(&tcp_md5sig_pool_lock);
2950                        return NULL;
2951                }
2952                pool = tcp_md5sig_pool;
2953                if (pool) {
2954                        /* oops, it has already been assigned. */
2955                        spin_unlock_bh(&tcp_md5sig_pool_lock);
2956                        __tcp_free_md5sig_pool(p);
2957                } else {
2958                        tcp_md5sig_pool = pool = p;
2959                        spin_unlock_bh(&tcp_md5sig_pool_lock);
2960                }
2961        }
2962        return pool;
2963}
2964EXPORT_SYMBOL(tcp_alloc_md5sig_pool);
2965
2966
2967/**
2968 *      tcp_get_md5sig_pool - get md5sig_pool for this user
2969 *
2970 *      We use percpu structure, so if we succeed, we exit with preemption
2971 *      and BH disabled, to make sure another thread or softirq handling
2972 *      wont try to get same context.
2973 */
2974struct tcp_md5sig_pool *tcp_get_md5sig_pool(void)
2975{
2976        struct tcp_md5sig_pool * __percpu *p;
2977
2978        local_bh_disable();
2979
2980        spin_lock(&tcp_md5sig_pool_lock);
2981        p = tcp_md5sig_pool;
2982        if (p)
2983                tcp_md5sig_users++;
2984        spin_unlock(&tcp_md5sig_pool_lock);
2985
2986        if (p)
2987                return *this_cpu_ptr(p);
2988
2989        local_bh_enable();
2990        return NULL;
2991}
2992EXPORT_SYMBOL(tcp_get_md5sig_pool);
2993
2994void tcp_put_md5sig_pool(void)
2995{
2996        local_bh_enable();
2997        tcp_free_md5sig_pool();
2998}
2999EXPORT_SYMBOL(tcp_put_md5sig_pool);
3000
3001int tcp_md5_hash_header(struct tcp_md5sig_pool *hp,
3002                        struct tcphdr *th)
3003{
3004        struct scatterlist sg;
3005        int err;
3006
3007        __sum16 old_checksum = th->check;
3008        th->check = 0;
3009        /* options aren't included in the hash */
3010        sg_init_one(&sg, th, sizeof(struct tcphdr));
3011        err = crypto_hash_update(&hp->md5_desc, &sg, sizeof(struct tcphdr));
3012        th->check = old_checksum;
3013        return err;
3014}
3015EXPORT_SYMBOL(tcp_md5_hash_header);
3016
3017int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *hp,
3018                          struct sk_buff *skb, unsigned header_len)
3019{
3020        struct scatterlist sg;
3021        const struct tcphdr *tp = tcp_hdr(skb);
3022        struct hash_desc *desc = &hp->md5_desc;
3023        unsigned i;
3024        const unsigned head_data_len = skb_headlen(skb) > header_len ?
3025                                       skb_headlen(skb) - header_len : 0;
3026        const struct skb_shared_info *shi = skb_shinfo(skb);
3027        struct sk_buff *frag_iter;
3028
3029        sg_init_table(&sg, 1);
3030
3031        sg_set_buf(&sg, ((u8 *) tp) + header_len, head_data_len);
3032        if (crypto_hash_update(desc, &sg, head_data_len))
3033                return 1;
3034
3035        for (i = 0; i < shi->nr_frags; ++i) {
3036                const struct skb_frag_struct *f = &shi->frags[i];
3037                sg_set_page(&sg, f->page, f->size, f->page_offset);
3038                if (crypto_hash_update(desc, &sg, f->size))
3039                        return 1;
3040        }
3041
3042        skb_walk_frags(skb, frag_iter)
3043                if (tcp_md5_hash_skb_data(hp, frag_iter, 0))
3044                        return 1;
3045
3046        return 0;
3047}
3048EXPORT_SYMBOL(tcp_md5_hash_skb_data);
3049
3050int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, struct tcp_md5sig_key *key)
3051{
3052        struct scatterlist sg;
3053
3054        sg_init_one(&sg, key->key, key->keylen);
3055        return crypto_hash_update(&hp->md5_desc, &sg, key->keylen);
3056}
3057EXPORT_SYMBOL(tcp_md5_hash_key);
3058
3059#endif
3060
3061/**
3062 * Each Responder maintains up to two secret values concurrently for
3063 * efficient secret rollover.  Each secret value has 4 states:
3064 *
3065 * Generating.  (tcp_secret_generating != tcp_secret_primary)
3066 *    Generates new Responder-Cookies, but not yet used for primary
3067 *    verification.  This is a short-term state, typically lasting only
3068 *    one round trip time (RTT).
3069 *
3070 * Primary.  (tcp_secret_generating == tcp_secret_primary)
3071 *    Used both for generation and primary verification.
3072 *
3073 * Retiring.  (tcp_secret_retiring != tcp_secret_secondary)
3074 *    Used for verification, until the first failure that can be
3075 *    verified by the newer Generating secret.  At that time, this
3076 *    cookie's state is changed to Secondary, and the Generating
3077 *    cookie's state is changed to Primary.  This is a short-term state,
3078 *    typically lasting only one round trip time (RTT).
3079 *
3080 * Secondary.  (tcp_secret_retiring == tcp_secret_secondary)
3081 *    Used for secondary verification, after primary verification
3082 *    failures.  This state lasts no more than twice the Maximum Segment
3083 *    Lifetime (2MSL).  Then, the secret is discarded.
3084 */
3085struct tcp_cookie_secret {
3086        /* The secret is divided into two parts.  The digest part is the
3087         * equivalent of previously hashing a secret and saving the state,
3088         * and serves as an initialization vector (IV).  The message part
3089         * serves as the trailing secret.
3090         */
3091        u32                             secrets[COOKIE_WORKSPACE_WORDS];
3092        unsigned long                   expires;
3093};
3094
3095#define TCP_SECRET_1MSL (HZ * TCP_PAWS_MSL)
3096#define TCP_SECRET_2MSL (HZ * TCP_PAWS_MSL * 2)
3097#define TCP_SECRET_LIFE (HZ * 600)
3098
3099static struct tcp_cookie_secret tcp_secret_one;
3100static struct tcp_cookie_secret tcp_secret_two;
3101
3102/* Essentially a circular list, without dynamic allocation. */
3103static struct tcp_cookie_secret *tcp_secret_generating;
3104static struct tcp_cookie_secret *tcp_secret_primary;
3105static struct tcp_cookie_secret *tcp_secret_retiring;
3106static struct tcp_cookie_secret *tcp_secret_secondary;
3107
3108static DEFINE_SPINLOCK(tcp_secret_locker);
3109
3110/* Select a pseudo-random word in the cookie workspace.
3111 */
3112static inline u32 tcp_cookie_work(const u32 *ws, const int n)
3113{
3114        return ws[COOKIE_DIGEST_WORDS + ((COOKIE_MESSAGE_WORDS-1) & ws[n])];
3115}
3116
3117/* Fill bakery[COOKIE_WORKSPACE_WORDS] with generator, updating as needed.
3118 * Called in softirq context.
3119 * Returns: 0 for success.
3120 */
3121int tcp_cookie_generator(u32 *bakery)
3122{
3123        unsigned long jiffy = jiffies;
3124
3125        if (unlikely(time_after_eq(jiffy, tcp_secret_generating->expires))) {
3126                spin_lock_bh(&tcp_secret_locker);
3127                if (!time_after_eq(jiffy, tcp_secret_generating->expires)) {
3128                        /* refreshed by another */
3129                        memcpy(bakery,
3130                               &tcp_secret_generating->secrets[0],
3131                               COOKIE_WORKSPACE_WORDS);
3132                } else {
3133                        /* still needs refreshing */
3134                        get_random_bytes(bakery, COOKIE_WORKSPACE_WORDS);
3135
3136                        /* The first time, paranoia assumes that the
3137                         * randomization function isn't as strong.  But,
3138                         * this secret initialization is delayed until
3139                         * the last possible moment (packet arrival).
3140                         * Although that time is observable, it is
3141                         * unpredictably variable.  Mash in the most
3142                         * volatile clock bits available, and expire the
3143                         * secret extra quickly.
3144                         */
3145                        if (unlikely(tcp_secret_primary->expires ==
3146                                     tcp_secret_secondary->expires)) {
3147                                struct timespec tv;
3148
3149                                getnstimeofday(&tv);
3150                                bakery[COOKIE_DIGEST_WORDS+0] ^=
3151                                        (u32)tv.tv_nsec;
3152
3153                                tcp_secret_secondary->expires = jiffy
3154                                        + TCP_SECRET_1MSL
3155                                        + (0x0f & tcp_cookie_work(bakery, 0));
3156                        } else {
3157                                tcp_secret_secondary->expires = jiffy
3158                                        + TCP_SECRET_LIFE
3159                                        + (0xff & tcp_cookie_work(bakery, 1));
3160                                tcp_secret_primary->expires = jiffy
3161                                        + TCP_SECRET_2MSL
3162                                        + (0x1f & tcp_cookie_work(bakery, 2));
3163                        }
3164                        memcpy(&tcp_secret_secondary->secrets[0],
3165                               bakery, COOKIE_WORKSPACE_WORDS);
3166
3167                        rcu_assign_pointer(tcp_secret_generating,
3168                                           tcp_secret_secondary);
3169                        rcu_assign_pointer(tcp_secret_retiring,
3170                                           tcp_secret_primary);
3171                        /*
3172                         * Neither call_rcu() nor synchronize_rcu() needed.
3173                         * Retiring data is not freed.  It is replaced after
3174                         * further (locked) pointer updates, and a quiet time
3175                         * (minimum 1MSL, maximum LIFE - 2MSL).
3176                         */
3177                }
3178                spin_unlock_bh(&tcp_secret_locker);
3179        } else {
3180                rcu_read_lock_bh();
3181                memcpy(bakery,
3182                       &rcu_dereference(tcp_secret_generating)->secrets[0],
3183                       COOKIE_WORKSPACE_WORDS);
3184                rcu_read_unlock_bh();
3185        }
3186        return 0;
3187}
3188EXPORT_SYMBOL(tcp_cookie_generator);
3189
3190void tcp_done(struct sock *sk)
3191{
3192        if (sk->sk_state == TCP_SYN_SENT || sk->sk_state == TCP_SYN_RECV)
3193                TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_ATTEMPTFAILS);
3194
3195        tcp_set_state(sk, TCP_CLOSE);
3196        tcp_clear_xmit_timers(sk);
3197
3198        sk->sk_shutdown = SHUTDOWN_MASK;
3199
3200        if (!sock_flag(sk, SOCK_DEAD))
3201                sk->sk_state_change(sk);
3202        else
3203                inet_csk_destroy_sock(sk);
3204}
3205EXPORT_SYMBOL_GPL(tcp_done);
3206
3207extern struct tcp_congestion_ops tcp_reno;
3208
3209static __initdata unsigned long thash_entries;
3210static int __init set_thash_entries(char *str)
3211{
3212        if (!str)
3213                return 0;
3214        thash_entries = simple_strtoul(str, &str, 0);
3215        return 1;
3216}
3217__setup("thash_entries=", set_thash_entries);
3218
3219void __init tcp_init(void)
3220{
3221        struct sk_buff *skb = NULL;
3222        unsigned long nr_pages, limit;
3223        int i, max_share, cnt;
3224        unsigned long jiffy = jiffies;
3225
3226        BUILD_BUG_ON(sizeof(struct tcp_skb_cb) > sizeof(skb->cb));
3227
3228        percpu_counter_init(&tcp_sockets_allocated, 0);
3229        percpu_counter_init(&tcp_orphan_count, 0);
3230        tcp_hashinfo.bind_bucket_cachep =
3231                kmem_cache_create("tcp_bind_bucket",
3232                                  sizeof(struct inet_bind_bucket), 0,
3233                                  SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
3234
3235        /* Size and allocate the main established and bind bucket
3236         * hash tables.
3237         *
3238         * The methodology is similar to that of the buffer cache.
3239         */
3240        tcp_hashinfo.ehash =
3241                alloc_large_system_hash("TCP established",
3242                                        sizeof(struct inet_ehash_bucket),
3243                                        thash_entries,
3244                                        (totalram_pages >= 128 * 1024) ?
3245                                        13 : 15,
3246                                        0,
3247                                        NULL,
3248                                        &tcp_hashinfo.ehash_mask,
3249                                        thash_entries ? 0 : 512 * 1024);
3250        for (i = 0; i <= tcp_hashinfo.ehash_mask; i++) {
3251                INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].chain, i);
3252                INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].twchain, i);
3253        }
3254        if (inet_ehash_locks_alloc(&tcp_hashinfo))
3255                panic("TCP: failed to alloc ehash_locks");
3256        tcp_hashinfo.bhash =
3257                alloc_large_system_hash("TCP bind",
3258                                        sizeof(struct inet_bind_hashbucket),
3259                                        tcp_hashinfo.ehash_mask + 1,
3260                                        (totalram_pages >= 128 * 1024) ?
3261                                        13 : 15,
3262                                        0,
3263                                        &tcp_hashinfo.bhash_size,
3264                                        NULL,
3265                                        64 * 1024);
3266        tcp_hashinfo.bhash_size = 1 << tcp_hashinfo.bhash_size;
3267        for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
3268                spin_lock_init(&tcp_hashinfo.bhash[i].lock);
3269                INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
3270        }
3271
3272
3273        cnt = tcp_hashinfo.ehash_mask + 1;
3274
3275        tcp_death_row.sysctl_max_tw_buckets = cnt / 2;
3276        sysctl_tcp_max_orphans = cnt / 2;
3277        sysctl_max_syn_backlog = max(128, cnt / 256);
3278
3279        /* Set the pressure threshold to be a fraction of global memory that
3280         * is up to 1/2 at 256 MB, decreasing toward zero with the amount of
3281         * memory, with a floor of 128 pages.
3282         */
3283        nr_pages = totalram_pages - totalhigh_pages;
3284        limit = min(nr_pages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT);
3285        limit = (limit * (nr_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
3286        limit = max(limit, 128UL);
3287        sysctl_tcp_mem[0] = limit / 4 * 3;
3288        sysctl_tcp_mem[1] = limit;
3289        sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2;
3290
3291        /* Set per-socket limits to no more than 1/128 the pressure threshold */
3292        limit = ((unsigned long)sysctl_tcp_mem[1]) << (PAGE_SHIFT - 7);
3293        max_share = min(4UL*1024*1024, limit);
3294
3295        sysctl_tcp_wmem[0] = SK_MEM_QUANTUM;
3296        sysctl_tcp_wmem[1] = 16*1024;
3297        sysctl_tcp_wmem[2] = max(64*1024, max_share);
3298
3299        sysctl_tcp_rmem[0] = SK_MEM_QUANTUM;
3300        sysctl_tcp_rmem[1] = 87380;
3301        sysctl_tcp_rmem[2] = max(87380, max_share);
3302
3303        printk(KERN_INFO "TCP: Hash tables configured "
3304               "(established %u bind %u)\n",
3305               tcp_hashinfo.ehash_mask + 1, tcp_hashinfo.bhash_size);
3306
3307        tcp_register_congestion_control(&tcp_reno);
3308
3309        memset(&tcp_secret_one.secrets[0], 0, sizeof(tcp_secret_one.secrets));
3310        memset(&tcp_secret_two.secrets[0], 0, sizeof(tcp_secret_two.secrets));
3311        tcp_secret_one.expires = jiffy; /* past due */
3312        tcp_secret_two.expires = jiffy; /* past due */
3313        tcp_secret_generating = &tcp_secret_one;
3314        tcp_secret_primary = &tcp_secret_one;
3315        tcp_secret_retiring = &tcp_secret_two;
3316        tcp_secret_secondary = &tcp_secret_two;
3317}
3318
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.