net/ipv4/tcp.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              Implementation of the Transmission Control Protocol(TCP).
   7  *
   8  * Authors:     Ross Biro
   9  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  10  *              Mark Evans, <evansmp@uhura.aston.ac.uk>
  11  *              Corey Minyard <wf-rch!minyard@relay.EU.net>
  12  *              Florian La Roche, <flla@stud.uni-sb.de>
  13  *              Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
  14  *              Linus Torvalds, <torvalds@cs.helsinki.fi>
  15  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  16  *              Matthew Dillon, <dillon@apollo.west.oic.com>
  17  *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
  18  *              Jorge Cwik, <jorge@laser.satlink.net>
  19  *
  20  * Fixes:
  21  *              Alan Cox        :       Numerous verify_area() calls
  22  *              Alan Cox        :       Set the ACK bit on a reset
  23  *              Alan Cox        :       Stopped it crashing if it closed while
  24  *                                      sk->inuse=1 and was trying to connect
  25  *                                      (tcp_err()).
  26  *              Alan Cox        :       All icmp error handling was broken
  27  *                                      pointers passed where wrong and the
  28  *                                      socket was looked up backwards. Nobody
  29  *                                      tested any icmp error code obviously.
  30  *              Alan Cox        :       tcp_err() now handled properly. It
  31  *                                      wakes people on errors. poll
  32  *                                      behaves and the icmp error race
  33  *                                      has gone by moving it into sock.c
  34  *              Alan Cox        :       tcp_send_reset() fixed to work for
  35  *                                      everything not just packets for
  36  *                                      unknown sockets.
  37  *              Alan Cox        :       tcp option processing.
  38  *              Alan Cox        :       Reset tweaked (still not 100%) [Had
  39  *                                      syn rule wrong]
  40  *              Herp Rosmanith  :       More reset fixes
  41  *              Alan Cox        :       No longer acks invalid rst frames.
  42  *                                      Acking any kind of RST is right out.
  43  *              Alan Cox        :       Sets an ignore me flag on an rst
  44  *                                      receive otherwise odd bits of prattle
  45  *                                      escape still
  46  *              Alan Cox        :       Fixed another acking RST frame bug.
  47  *                                      Should stop LAN workplace lockups.
  48  *              Alan Cox        :       Some tidyups using the new skb list
  49  *                                      facilities
  50  *              Alan Cox        :       sk->keepopen now seems to work
  51  *              Alan Cox        :       Pulls options out correctly on accepts
  52  *              Alan Cox        :       Fixed assorted sk->rqueue->next errors
  53  *              Alan Cox        :       PSH doesn't end a TCP read. Switched a
  54  *                                      bit to skb ops.
  55  *              Alan Cox        :       Tidied tcp_data to avoid a potential
  56  *                                      nasty.
  57  *              Alan Cox        :       Added some better commenting, as the
  58  *                                      tcp is hard to follow
  59  *              Alan Cox        :       Removed incorrect check for 20 * psh
  60  *      Michael O'Reilly        :       ack < copied bug fix.
  61  *      Johannes Stille         :       Misc tcp fixes (not all in yet).
  62  *              Alan Cox        :       FIN with no memory -> CRASH
  63  *              Alan Cox        :       Added socket option proto entries.
  64  *                                      Also added awareness of them to accept.
  65  *              Alan Cox        :       Added TCP options (SOL_TCP)
  66  *              Alan Cox        :       Switched wakeup calls to callbacks,
  67  *                                      so the kernel can layer network
  68  *                                      sockets.
  69  *              Alan Cox        :       Use ip_tos/ip_ttl settings.
  70  *              Alan Cox        :       Handle FIN (more) properly (we hope).
  71  *              Alan Cox        :       RST frames sent on unsynchronised
  72  *                                      state ack error.
  73  *              Alan Cox        :       Put in missing check for SYN bit.
  74  *              Alan Cox        :       Added tcp_select_window() aka NET2E
  75  *                                      window non shrink trick.
  76  *              Alan Cox        :       Added a couple of small NET2E timer
  77  *                                      fixes
  78  *              Charles Hedrick :       TCP fixes
  79  *              Toomas Tamm     :       TCP window fixes
  80  *              Alan Cox        :       Small URG fix to rlogin ^C ack fight
  81  *              Charles Hedrick :       Rewrote most of it to actually work
  82  *              Linus           :       Rewrote tcp_read() and URG handling
  83  *                                      completely
  84  *              Gerhard Koerting:       Fixed some missing timer handling
  85  *              Matthew Dillon  :       Reworked TCP machine states as per RFC
  86  *              Gerhard Koerting:       PC/TCP workarounds
  87  *              Adam Caldwell   :       Assorted timer/timing errors
  88  *              Matthew Dillon  :       Fixed another RST bug
  89  *              Alan Cox        :       Move to kernel side addressing changes.
  90  *              Alan Cox        :       Beginning work on TCP fastpathing
  91  *                                      (not yet usable)
  92  *              Arnt Gulbrandsen:       Turbocharged tcp_check() routine.
  93  *              Alan Cox        :       TCP fast path debugging
  94  *              Alan Cox        :       Window clamping
  95  *              Michael Riepe   :       Bug in tcp_check()
  96  *              Matt Dillon     :       More TCP improvements and RST bug fixes
  97  *              Matt Dillon     :       Yet more small nasties remove from the
  98  *                                      TCP code (Be very nice to this man if
  99  *                                      tcp finally works 100%) 8)
 100  *              Alan Cox        :       BSD accept semantics.
 101  *              Alan Cox        :       Reset on closedown bug.
 102  *      Peter De Schrijver      :       ENOTCONN check missing in tcp_sendto().
 103  *              Michael Pall    :       Handle poll() after URG properly in
 104  *                                      all cases.
 105  *              Michael Pall    :       Undo the last fix in tcp_read_urg()
 106  *                                      (multi URG PUSH broke rlogin).
 107  *              Michael Pall    :       Fix the multi URG PUSH problem in
 108  *                                      tcp_readable(), poll() after URG
 109  *                                      works now.
 110  *              Michael Pall    :       recv(...,MSG_OOB) never blocks in the
 111  *                                      BSD api.
 112  *              Alan Cox        :       Changed the semantics of sk->socket to
 113  *                                      fix a race and a signal problem with
 114  *                                      accept() and async I/O.
 115  *              Alan Cox        :       Relaxed the rules on tcp_sendto().
 116  *              Yury Shevchuk   :       Really fixed accept() blocking problem.
 117  *              Craig I. Hagan  :       Allow for BSD compatible TIME_WAIT for
 118  *                                      clients/servers which listen in on
 119  *                                      fixed ports.
 120  *              Alan Cox        :       Cleaned the above up and shrank it to
 121  *                                      a sensible code size.
 122  *              Alan Cox        :       Self connect lockup fix.
 123  *              Alan Cox        :       No connect to multicast.
 124  *              Ross Biro       :       Close unaccepted children on master
 125  *                                      socket close.
 126  *              Alan Cox        :       Reset tracing code.
 127  *              Alan Cox        :       Spurious resets on shutdown.
 128  *              Alan Cox        :       Giant 15 minute/60 second timer error
 129  *              Alan Cox        :       Small whoops in polling before an
 130  *                                      accept.
 131  *              Alan Cox        :       Kept the state trace facility since
 132  *                                      it's handy for debugging.
 133  *              Alan Cox        :       More reset handler fixes.
 134  *              Alan Cox        :       Started rewriting the code based on
 135  *                                      the RFC's for other useful protocol
 136  *                                      references see: Comer, KA9Q NOS, and
 137  *                                      for a reference on the difference
 138  *                                      between specifications and how BSD
 139  *                                      works see the 4.4lite source.
 140  *              A.N.Kuznetsov   :       Don't time wait on completion of tidy
 141  *                                      close.
 142  *              Linus Torvalds  :       Fin/Shutdown & copied_seq changes.
 143  *              Linus Torvalds  :       Fixed BSD port reuse to work first syn
 144  *              Alan Cox        :       Reimplemented timers as per the RFC
 145  *                                      and using multiple timers for sanity.
 146  *              Alan Cox        :       Small bug fixes, and a lot of new
 147  *                                      comments.
 148  *              Alan Cox        :       Fixed dual reader crash by locking
 149  *                                      the buffers (much like datagram.c)
 150  *              Alan Cox        :       Fixed stuck sockets in probe. A probe
 151  *                                      now gets fed up of retrying without
 152  *                                      (even a no space) answer.
 153  *              Alan Cox        :       Extracted closing code better
 154  *              Alan Cox        :       Fixed the closing state machine to
 155  *                                      resemble the RFC.
 156  *              Alan Cox        :       More 'per spec' fixes.
 157  *              Jorge Cwik      :       Even faster checksumming.
 158  *              Alan Cox        :       tcp_data() doesn't ack illegal PSH
 159  *                                      only frames. At least one pc tcp stack
 160  *                                      generates them.
 161  *              Alan Cox        :       Cache last socket.
 162  *              Alan Cox        :       Per route irtt.
 163  *              Matt Day        :       poll()->select() match BSD precisely on error
 164  *              Alan Cox        :       New buffers
 165  *              Marc Tamsky     :       Various sk->prot->retransmits and
 166  *                                      sk->retransmits misupdating fixed.
 167  *                                      Fixed tcp_write_timeout: stuck close,
 168  *                                      and TCP syn retries gets used now.
 169  *              Mark Yarvis     :       In tcp_read_wakeup(), don't send an
 170  *                                      ack if state is TCP_CLOSED.
 171  *              Alan Cox        :       Look up device on a retransmit - routes may
 172  *                                      change. Doesn't yet cope with MSS shrink right
 173  *                                      but it's a start!
 174  *              Marc Tamsky     :       Closing in closing fixes.
 175  *              Mike Shaver     :       RFC1122 verifications.
 176  *              Alan Cox        :       rcv_saddr errors.
 177  *              Alan Cox        :       Block double connect().
 178  *              Alan Cox        :       Small hooks for enSKIP.
 179  *              Alexey Kuznetsov:       Path MTU discovery.
 180  *              Alan Cox        :       Support soft errors.
 181  *              Alan Cox        :       Fix MTU discovery pathological case
 182  *                                      when the remote claims no mtu!
 183  *              Marc Tamsky     :       TCP_CLOSE fix.
 184  *              Colin (G3TNE)   :       Send a reset on syn ack replies in
 185  *                                      window but wrong (fixes NT lpd problems)
 186  *              Pedro Roque     :       Better TCP window handling, delayed ack.
 187  *              Joerg Reuter    :       No modification of locked buffers in
 188  *                                      tcp_do_retransmit()
 189  *              Eric Schenk     :       Changed receiver side silly window
 190  *                                      avoidance algorithm to BSD style
 191  *                                      algorithm. This doubles throughput
 192  *                                      against machines running Solaris,
 193  *                                      and seems to result in general
 194  *                                      improvement.
 195  *      Stefan Magdalinski      :       adjusted tcp_readable() to fix FIONREAD
 196  *      Willy Konynenberg       :       Transparent proxying support.
 197  *      Mike McLagan            :       Routing by source
 198  *              Keith Owens     :       Do proper merging with partial SKB's in
 199  *                                      tcp_do_sendmsg to avoid burstiness.
 200  *              Eric Schenk     :       Fix fast close down bug with
 201  *                                      shutdown() followed by close().
 202  *              Andi Kleen      :       Make poll agree with SIGIO
 203  *      Salvatore Sanfilippo    :       Support SO_LINGER with linger == 1 and
 204  *                                      lingertime == 0 (RFC 793 ABORT Call)
 205  *      Hirokazu Takahashi      :       Use copy_from_user() instead of
 206  *                                      csum_and_copy_from_user() if possible.
 207  *
 208  *              This program is free software; you can redistribute it and/or
 209  *              modify it under the terms of the GNU General Public License
 210  *              as published by the Free Software Foundation; either version
 211  *              2 of the License, or(at your option) any later version.
 212  *
 213  * Description of States:
 214  *
 215  *      TCP_SYN_SENT            sent a connection request, waiting for ack
 216  *
 217  *      TCP_SYN_RECV            received a connection request, sent ack,
 218  *                              waiting for final ack in three-way handshake.
 219  *
 220  *      TCP_ESTABLISHED         connection established
 221  *
 222  *      TCP_FIN_WAIT1           our side has shutdown, waiting to complete
 223  *                              transmission of remaining buffered data
 224  *
 225  *      TCP_FIN_WAIT2           all buffered data sent, waiting for remote
 226  *                              to shutdown
 227  *
 228  *      TCP_CLOSING             both sides have shutdown but we still have
 229  *                              data we have to finish sending
 230  *
 231  *      TCP_TIME_WAIT           timeout to catch resent junk before entering
 232  *                              closed, can only be entered from FIN_WAIT2
 233  *                              or CLOSING.  Required because the other end
 234  *                              may not have gotten our last ACK causing it
 235  *                              to retransmit the data packet (which we ignore)
 236  *
 237  *      TCP_CLOSE_WAIT          remote side has shutdown and is waiting for
 238  *                              us to finish writing our data and to shutdown
 239  *                              (we have to close() to move on to LAST_ACK)
 240  *
 241  *      TCP_LAST_ACK            out side has shutdown after remote has
 242  *                              shutdown.  There may still be data in our
 243  *                              buffer that we have to finish sending
 244  *
 245  *      TCP_CLOSE               socket is finished
 246  */
 247
 248 #define pr_fmt(fmt) "TCP: " fmt
 249
 250 #include <linux/kernel.h>
 251 #include <linux/module.h>
 252 #include <linux/types.h>
 253 #include <linux/fcntl.h>
 254 #include <linux/poll.h>
 255 #include <linux/init.h>
 256 #include <linux/fs.h>
 257 #include <linux/skbuff.h>
 258 #include <linux/scatterlist.h>
 259 #include <linux/splice.h>
 260 #include <linux/net.h>
 261 #include <linux/socket.h>
 262 #include <linux/random.h>
 263 #include <linux/bootmem.h>
 264 #include <linux/highmem.h>
 265 #include <linux/swap.h>
 266 #include <linux/cache.h>
 267 #include <linux/err.h>
 268 #include <linux/crypto.h>
 269 #include <linux/time.h>
 270 #include <linux/slab.h>
 271
 272 #include <net/icmp.h>
 273 #include <net/tcp.h>
 274 #include <net/xfrm.h>
 275 #include <net/ip.h>
 276 #include <net/netdma.h>
 277 #include <net/sock.h>
 278
 279 #include <asm/uaccess.h>
 280 #include <asm/ioctls.h>
 281
 282 int sysctl_tcp_fin_timeout __read_mostly = TCP_FIN_TIMEOUT;
 283
 284 struct percpu_counter tcp_orphan_count;
 285 EXPORT_SYMBOL_GPL(tcp_orphan_count);
 286
 287 int sysctl_tcp_wmem[3] __read_mostly;
 288 int sysctl_tcp_rmem[3] __read_mostly;
 289
 290 EXPORT_SYMBOL(sysctl_tcp_rmem);
 291 EXPORT_SYMBOL(sysctl_tcp_wmem);
 292
 293 atomic_long_t tcp_memory_allocated;     /* Current allocated memory. */
 294 EXPORT_SYMBOL(tcp_memory_allocated);
 295
 296 /*
 297  * Current number of TCP sockets.
 298  */
 299 struct percpu_counter tcp_sockets_allocated;
 300 EXPORT_SYMBOL(tcp_sockets_allocated);
 301
 302 /*
 303  * TCP splice context
 304  */
 305 struct 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  */
 317 int tcp_memory_pressure __read_mostly;
 318 EXPORT_SYMBOL(tcp_memory_pressure);
 319
 320 void 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 }
 327 EXPORT_SYMBOL(tcp_enter_memory_pressure);
 328
 329 /* Convert seconds to retransmits based on initial and max timeout */
 330 static 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 */
 350 static 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 /* Address-family independent initialization for a tcp_sock.
 367  *
 368  * NOTE: A lot of things set to zero explicitly by call to
 369  *       sk_alloc() so need not be done here.
 370  */
 371 void tcp_init_sock(struct sock *sk)
 372 {
 373         struct inet_connection_sock *icsk = inet_csk(sk);
 374         struct tcp_sock *tp = tcp_sk(sk);
 375
 376         skb_queue_head_init(&tp->out_of_order_queue);
 377         tcp_init_xmit_timers(sk);
 378         tcp_prequeue_init(tp);
 379
 380         icsk->icsk_rto = TCP_TIMEOUT_INIT;
 381         tp->mdev = TCP_TIMEOUT_INIT;
 382
 383         /* So many TCP implementations out there (incorrectly) count the
 384          * initial SYN frame in their delayed-ACK and congestion control
 385          * algorithms that we must have the following bandaid to talk
 386          * efficiently to them.  -DaveM
 387          */
 388         tp->snd_cwnd = TCP_INIT_CWND;
 389
 390         /* See draft-stevens-tcpca-spec-01 for discussion of the
 391          * initialization of these values.
 392          */
 393         tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
 394         tp->snd_cwnd_clamp = ~0;
 395         tp->mss_cache = TCP_MSS_DEFAULT;
 396
 397         tp->reordering = sysctl_tcp_reordering;
 398         tcp_enable_early_retrans(tp);
 399         icsk->icsk_ca_ops = &tcp_init_congestion_ops;
 400
 401         sk->sk_state = TCP_CLOSE;
 402
 403         sk->sk_write_space = sk_stream_write_space;
 404         sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
 405
 406         icsk->icsk_sync_mss = tcp_sync_mss;
 407
 408         /* TCP Cookie Transactions */
 409         if (sysctl_tcp_cookie_size > 0) {
 410                 /* Default, cookies without s_data_payload. */
 411                 tp->cookie_values =
 412                         kzalloc(sizeof(*tp->cookie_values),
 413                                 sk->sk_allocation);
 414                 if (tp->cookie_values != NULL)
 415                         kref_init(&tp->cookie_values->kref);
 416         }
 417         /* Presumed zeroed, in order of appearance:
 418          *      cookie_in_always, cookie_out_never,
 419          *      s_data_constant, s_data_in, s_data_out
 420          */
 421         sk->sk_sndbuf = sysctl_tcp_wmem[1];
 422         sk->sk_rcvbuf = sysctl_tcp_rmem[1];
 423
 424         local_bh_disable();
 425         sock_update_memcg(sk);
 426         sk_sockets_allocated_inc(sk);
 427         local_bh_enable();
 428 }
 429 EXPORT_SYMBOL(tcp_init_sock);
 430
 431 /*
 432  *      Wait for a TCP event.
 433  *
 434  *      Note that we don't need to lock the socket, as the upper poll layers
 435  *      take care of normal races (between the test and the event) and we don't
 436  *      go look at any of the socket buffers directly.
 437  */
 438 unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
 439 {
 440         unsigned int mask;
 441         struct sock *sk = sock->sk;
 442         const struct tcp_sock *tp = tcp_sk(sk);
 443
 444         sock_poll_wait(file, sk_sleep(sk), wait);
 445         if (sk->sk_state == TCP_LISTEN)
 446                 return inet_csk_listen_poll(sk);
 447
 448         /* Socket is not locked. We are protected from async events
 449          * by poll logic and correct handling of state changes
 450          * made by other threads is impossible in any case.
 451          */
 452
 453         mask = 0;
 454
 455         /*
 456          * POLLHUP is certainly not done right. But poll() doesn't
 457          * have a notion of HUP in just one direction, and for a
 458          * socket the read side is more interesting.
 459          *
 460          * Some poll() documentation says that POLLHUP is incompatible
 461          * with the POLLOUT/POLLWR flags, so somebody should check this
 462          * all. But careful, it tends to be safer to return too many
 463          * bits than too few, and you can easily break real applications
 464          * if you don't tell them that something has hung up!
 465          *
 466          * Check-me.
 467          *
 468          * Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and
 469          * our fs/select.c). It means that after we received EOF,
 470          * poll always returns immediately, making impossible poll() on write()
 471          * in state CLOSE_WAIT. One solution is evident --- to set POLLHUP
 472          * if and only if shutdown has been made in both directions.
 473          * Actually, it is interesting to look how Solaris and DUX
 474          * solve this dilemma. I would prefer, if POLLHUP were maskable,
 475          * then we could set it on SND_SHUTDOWN. BTW examples given
 476          * in Stevens' books assume exactly this behaviour, it explains
 477          * why POLLHUP is incompatible with POLLOUT.    --ANK
 478          *
 479          * NOTE. Check for TCP_CLOSE is added. The goal is to prevent
 480          * blocking on fresh not-connected or disconnected socket. --ANK
 481          */
 482         if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == TCP_CLOSE)
 483                 mask |= POLLHUP;
 484         if (sk->sk_shutdown & RCV_SHUTDOWN)
 485                 mask |= POLLIN | POLLRDNORM | POLLRDHUP;
 486
 487         /* Connected? */
 488         if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV)) {
 489                 int target = sock_rcvlowat(sk, 0, INT_MAX);
 490
 491                 if (tp->urg_seq == tp->copied_seq &&
 492                     !sock_flag(sk, SOCK_URGINLINE) &&
 493                     tp->urg_data)
 494                         target++;
 495
 496                 /* Potential race condition. If read of tp below will
 497                  * escape above sk->sk_state, we can be illegally awaken
 498                  * in SYN_* states. */
 499                 if (tp->rcv_nxt - tp->copied_seq >= target)
 500                         mask |= POLLIN | POLLRDNORM;
 501
 502                 if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
 503                         if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
 504                                 mask |= POLLOUT | POLLWRNORM;
 505                         } else {  /* send SIGIO later */
 506                                 set_bit(SOCK_ASYNC_NOSPACE,
 507                                         &sk->sk_socket->flags);
 508                                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 509
 510                                 /* Race breaker. If space is freed after
 511                                  * wspace test but before the flags are set,
 512                                  * IO signal will be lost.
 513                                  */
 514                                 if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk))
 515                                         mask |= POLLOUT | POLLWRNORM;
 516                         }
 517                 } else
 518                         mask |= POLLOUT | POLLWRNORM;
 519
 520                 if (tp->urg_data & TCP_URG_VALID)
 521                         mask |= POLLPRI;
 522         }
 523         /* This barrier is coupled with smp_wmb() in tcp_reset() */
 524         smp_rmb();
 525         if (sk->sk_err)
 526                 mask |= POLLERR;
 527
 528         return mask;
 529 }
 530 EXPORT_SYMBOL(tcp_poll);
 531
 532 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
 533 {
 534         struct tcp_sock *tp = tcp_sk(sk);
 535         int answ;
 536
 537         switch (cmd) {
 538         case SIOCINQ:
 539                 if (sk->sk_state == TCP_LISTEN)
 540                         return -EINVAL;
 541
 542                 lock_sock(sk);
 543                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
 544                         answ = 0;
 545                 else if (sock_flag(sk, SOCK_URGINLINE) ||
 546                          !tp->urg_data ||
 547                          before(tp->urg_seq, tp->copied_seq) ||
 548                          !before(tp->urg_seq, tp->rcv_nxt)) {
 549                         struct sk_buff *skb;
 550
 551                         answ = tp->rcv_nxt - tp->copied_seq;
 552
 553                         /* Subtract 1, if FIN is in queue. */
 554                         skb = skb_peek_tail(&sk->sk_receive_queue);
 555                         if (answ && skb)
 556                                 answ -= tcp_hdr(skb)->fin;
 557                 } else
 558                         answ = tp->urg_seq - tp->copied_seq;
 559                 release_sock(sk);
 560                 break;
 561         case SIOCATMARK:
 562                 answ = tp->urg_data && tp->urg_seq == tp->copied_seq;
 563                 break;
 564         case SIOCOUTQ:
 565                 if (sk->sk_state == TCP_LISTEN)
 566                         return -EINVAL;
 567
 568                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
 569                         answ = 0;
 570                 else
 571                         answ = tp->write_seq - tp->snd_una;
 572                 break;
 573         case SIOCOUTQNSD:
 574                 if (sk->sk_state == TCP_LISTEN)
 575                         return -EINVAL;
 576
 577                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
 578                         answ = 0;
 579                 else
 580                         answ = tp->write_seq - tp->snd_nxt;
 581                 break;
 582         default:
 583                 return -ENOIOCTLCMD;
 584         }
 585
 586         return put_user(answ, (int __user *)arg);
 587 }
 588 EXPORT_SYMBOL(tcp_ioctl);
 589
 590 static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
 591 {
 592         TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH;
 593         tp->pushed_seq = tp->write_seq;
 594 }
 595
 596 static inline bool forced_push(const struct tcp_sock *tp)
 597 {
 598         return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
 599 }
 600
 601 static inline void skb_entail(struct sock *sk, struct sk_buff *skb)
 602 {
 603         struct tcp_sock *tp = tcp_sk(sk);
 604         struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
 605
 606         skb->csum    = 0;
 607         tcb->seq     = tcb->end_seq = tp->write_seq;
 608         tcb->tcp_flags = TCPHDR_ACK;
 609         tcb->sacked  = 0;
 610         skb_header_release(skb);
 611         tcp_add_write_queue_tail(sk, skb);
 612         sk->sk_wmem_queued += skb->truesize;
 613         sk_mem_charge(sk, skb->truesize);
 614         if (tp->nonagle & TCP_NAGLE_PUSH)
 615                 tp->nonagle &= ~TCP_NAGLE_PUSH;
 616 }
 617
 618 static inline void tcp_mark_urg(struct tcp_sock *tp, int flags)
 619 {
 620         if (flags & MSG_OOB)
 621                 tp->snd_up = tp->write_seq;
 622 }
 623
 624 static inline void tcp_push(struct sock *sk, int flags, int mss_now,
 625                             int nonagle)
 626 {
 627         if (tcp_send_head(sk)) {
 628                 struct tcp_sock *tp = tcp_sk(sk);
 629
 630                 if (!(flags & MSG_MORE) || forced_push(tp))
 631                         tcp_mark_push(tp, tcp_write_queue_tail(sk));
 632
 633                 tcp_mark_urg(tp, flags);
 634                 __tcp_push_pending_frames(sk, mss_now,
 635                                           (flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle);
 636         }
 637 }
 638
 639 static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
 640                                 unsigned int offset, size_t len)
 641 {
 642         struct tcp_splice_state *tss = rd_desc->arg.data;
 643         int ret;
 644
 645         ret = skb_splice_bits(skb, offset, tss->pipe, min(rd_desc->count, len),
 646                               tss->flags);
 647         if (ret > 0)
 648                 rd_desc->count -= ret;
 649         return ret;
 650 }
 651
 652 static int __tcp_splice_read(struct sock *sk, struct tcp_splice_state *tss)
 653 {
 654         /* Store TCP splice context information in read_descriptor_t. */
 655         read_descriptor_t rd_desc = {
 656                 .arg.data = tss,
 657                 .count    = tss->len,
 658         };
 659
 660         return tcp_read_sock(sk, &rd_desc, tcp_splice_data_recv);
 661 }
 662
 663 /**
 664  *  tcp_splice_read - splice data from TCP socket to a pipe
 665  * @sock:       socket to splice from
 666  * @ppos:       position (not valid)
 667  * @pipe:       pipe to splice to
 668  * @len:        number of bytes to splice
 669  * @flags:      splice modifier flags
 670  *
 671  * Description:
 672  *    Will read pages from given socket and fill them into a pipe.
 673  *
 674  **/
 675 ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
 676                         struct pipe_inode_info *pipe, size_t len,
 677                         unsigned int flags)
 678 {
 679         struct sock *sk = sock->sk;
 680         struct tcp_splice_state tss = {
 681                 .pipe = pipe,
 682                 .len = len,
 683                 .flags = flags,
 684         };
 685         long timeo;
 686         ssize_t spliced;
 687         int ret;
 688
 689         sock_rps_record_flow(sk);
 690         /*
 691          * We can't seek on a socket input
 692          */
 693         if (unlikely(*ppos))
 694                 return -ESPIPE;
 695
 696         ret = spliced = 0;
 697
 698         lock_sock(sk);
 699
 700         timeo = sock_rcvtimeo(sk, sock->file->f_flags & O_NONBLOCK);
 701         while (tss.len) {
 702                 ret = __tcp_splice_read(sk, &tss);
 703                 if (ret < 0)
 704                         break;
 705                 else if (!ret) {
 706                         if (spliced)
 707                                 break;
 708                         if (sock_flag(sk, SOCK_DONE))
 709                                 break;
 710                         if (sk->sk_err) {
 711                                 ret = sock_error(sk);
 712                                 break;
 713                         }
 714                         if (sk->sk_shutdown & RCV_SHUTDOWN)
 715                                 break;
 716                         if (sk->sk_state == TCP_CLOSE) {
 717                                 /*
 718                                  * This occurs when user tries to read
 719                                  * from never connected socket.
 720                                  */
 721                                 if (!sock_flag(sk, SOCK_DONE))
 722                                         ret = -ENOTCONN;
 723                                 break;
 724                         }
 725                         if (!timeo) {
 726                                 ret = -EAGAIN;
 727                                 break;
 728                         }
 729                         sk_wait_data(sk, &timeo);
 730                         if (signal_pending(current)) {
 731                                 ret = sock_intr_errno(timeo);
 732                                 break;
 733                         }
 734                         continue;
 735                 }
 736                 tss.len -= ret;
 737                 spliced += ret;
 738
 739                 if (!timeo)
 740                         break;
 741                 release_sock(sk);
 742                 lock_sock(sk);
 743
 744                 if (sk->sk_err || sk->sk_state == TCP_CLOSE ||
 745                     (sk->sk_shutdown & RCV_SHUTDOWN) ||
 746                     signal_pending(current))
 747                         break;
 748         }
 749
 750         release_sock(sk);
 751
 752         if (spliced)
 753                 return spliced;
 754
 755         return ret;
 756 }
 757 EXPORT_SYMBOL(tcp_splice_read);
 758
 759 struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp)
 760 {
 761         struct sk_buff *skb;
 762
 763         /* The TCP header must be at least 32-bit aligned.  */
 764         size = ALIGN(size, 4);
 765
 766         skb = alloc_skb_fclone(size + sk->sk_prot->max_header, gfp);
 767         if (skb) {
 768                 if (sk_wmem_schedule(sk, skb->truesize)) {
 769                         skb_reserve(skb, sk->sk_prot->max_header);
 770                         /*
 771                          * Make sure that we have exactly size bytes
 772                          * available to the caller, no more, no less.
 773                          */
 774                         skb->avail_size = size;
 775                         return skb;
 776                 }
 777                 __kfree_skb(skb);
 778         } else {
 779                 sk->sk_prot->enter_memory_pressure(sk);
 780                 sk_stream_moderate_sndbuf(sk);
 781         }
 782         return NULL;
 783 }
 784
 785 static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,
 786                                        int large_allowed)
 787 {
 788         struct tcp_sock *tp = tcp_sk(sk);
 789         u32 xmit_size_goal, old_size_goal;
 790
 791         xmit_size_goal = mss_now;
 792
 793         if (large_allowed && sk_can_gso(sk)) {
 794                 xmit_size_goal = ((sk->sk_gso_max_size - 1) -
 795                                   inet_csk(sk)->icsk_af_ops->net_header_len -
 796                                   inet_csk(sk)->icsk_ext_hdr_len -
 797                                   tp->tcp_header_len);
 798
 799                 xmit_size_goal = tcp_bound_to_half_wnd(tp, xmit_size_goal);
 800
 801                 /* We try hard to avoid divides here */
 802                 old_size_goal = tp->xmit_size_goal_segs * mss_now;
 803
 804                 if (likely(old_size_goal <= xmit_size_goal &&
 805                            old_size_goal + mss_now > xmit_size_goal)) {
 806                         xmit_size_goal = old_size_goal;
 807                 } else {
 808                         tp->xmit_size_goal_segs = xmit_size_goal / mss_now;
 809                         xmit_size_goal = tp->xmit_size_goal_segs * mss_now;
 810                 }
 811         }
 812
 813         return max(xmit_size_goal, mss_now);
 814 }
 815
 816 static int tcp_send_mss(struct sock *sk, int *size_goal, int flags)
 817 {
 818         int mss_now;
 819
 820         mss_now = tcp_current_mss(sk);
 821         *size_goal = tcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));
 822
 823         return mss_now;
 824 }
 825
 826 static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset,
 827                          size_t psize, int flags)
 828 {
 829         struct tcp_sock *tp = tcp_sk(sk);
 830         int mss_now, size_goal;
 831         int err;
 832         ssize_t copied;
 833         long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 834
 835         /* Wait for a connection to finish. */
 836         if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
 837                 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
 838                         goto out_err;
 839
 840         clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 841
 842         mss_now = tcp_send_mss(sk, &size_goal, flags);
 843         copied = 0;
 844
 845         err = -EPIPE;
 846         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 847                 goto out_err;
 848
 849         while (psize > 0) {
 850                 struct sk_buff *skb = tcp_write_queue_tail(sk);
 851                 struct page *page = pages[poffset / PAGE_SIZE];
 852                 int copy, i;
 853                 int offset = poffset % PAGE_SIZE;
 854                 int size = min_t(size_t, psize, PAGE_SIZE - offset);
 855                 bool can_coalesce;
 856
 857                 if (!tcp_send_head(sk) || (copy = size_goal - skb->len) <= 0) {
 858 new_segment:
 859                         if (!sk_stream_memory_free(sk))
 860                                 goto wait_for_sndbuf;
 861
 862                         skb = sk_stream_alloc_skb(sk, 0, sk->sk_allocation);
 863                         if (!skb)
 864                                 goto wait_for_memory;
 865
 866                         skb_entail(sk, skb);
 867                         copy = size_goal;
 868                 }
 869
 870                 if (copy > size)
 871                         copy = size;
 872
 873                 i = skb_shinfo(skb)->nr_frags;
 874                 can_coalesce = skb_can_coalesce(skb, i, page, offset);
 875                 if (!can_coalesce && i >= MAX_SKB_FRAGS) {
 876                         tcp_mark_push(tp, skb);
 877                         goto new_segment;
 878                 }
 879                 if (!sk_wmem_schedule(sk, copy))
 880                         goto wait_for_memory;
 881
 882                 if (can_coalesce) {
 883                         skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
 884                 } else {
 885                         get_page(page);
 886                         skb_fill_page_desc(skb, i, page, offset, copy);
 887                 }
 888
 889                 skb->len += copy;
 890                 skb->data_len += copy;
 891                 skb->truesize += copy;
 892                 sk->sk_wmem_queued += copy;
 893                 sk_mem_charge(sk, copy);
 894                 skb->ip_summed = CHECKSUM_PARTIAL;
 895                 tp->write_seq += copy;
 896                 TCP_SKB_CB(skb)->end_seq += copy;
 897                 skb_shinfo(skb)->gso_segs = 0;
 898
 899                 if (!copied)
 900                         TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
 901
 902                 copied += copy;
 903                 poffset += copy;
 904                 if (!(psize -= copy))
 905                         goto out;
 906
 907                 if (skb->len < size_goal || (flags & MSG_OOB))
 908                         continue;
 909
 910                 if (forced_push(tp)) {
 911                         tcp_mark_push(tp, skb);
 912                         __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
 913                 } else if (skb == tcp_send_head(sk))
 914                         tcp_push_one(sk, mss_now);
 915                 continue;
 916
 917 wait_for_sndbuf:
 918                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 919 wait_for_memory:
 920                 if (copied)
 921                         tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
 922
 923                 if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
 924                         goto do_error;
 925
 926                 mss_now = tcp_send_mss(sk, &size_goal, flags);
 927         }
 928
 929 out:
 930         if (copied && !(flags & MSG_SENDPAGE_NOTLAST))
 931                 tcp_push(sk, flags, mss_now, tp->nonagle);
 932         return copied;
 933
 934 do_error:
 935         if (copied)
 936                 goto out;
 937 out_err:
 938         return sk_stream_error(sk, flags, err);
 939 }
 940
 941 int tcp_sendpage(struct sock *sk, struct page *page, int offset,
 942                  size_t size, int flags)
 943 {
 944         ssize_t res;
 945
 946         if (!(sk->sk_route_caps & NETIF_F_SG) ||
 947             !(sk->sk_route_caps & NETIF_F_ALL_CSUM))
 948                 return sock_no_sendpage(sk->sk_socket, page, offset, size,
 949                                         flags);
 950
 951         lock_sock(sk);
 952         res = do_tcp_sendpages(sk, &page, offset, size, flags);
 953         release_sock(sk);
 954         return res;
 955 }
 956 EXPORT_SYMBOL(tcp_sendpage);
 957
 958 static inline int select_size(const struct sock *sk, bool sg)
 959 {
 960         const struct tcp_sock *tp = tcp_sk(sk);
 961         int tmp = tp->mss_cache;
 962
 963         if (sg) {
 964                 if (sk_can_gso(sk)) {
 965                         /* Small frames wont use a full page:
 966                          * Payload will immediately follow tcp header.
 967                          */
 968                         tmp = SKB_WITH_OVERHEAD(2048 - MAX_TCP_HEADER);
 969                 } else {
 970                         int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
 971
 972                         if (tmp >= pgbreak &&
 973                             tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
 974                                 tmp = pgbreak;
 975                 }
 976         }
 977
 978         return tmp;
 979 }
 980
 981 int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 982                 size_t size)
 983 {
 984         struct iovec *iov;
 985         struct tcp_sock *tp = tcp_sk(sk);
 986         struct sk_buff *skb;
 987         int iovlen, flags, err, copied;
 988         int mss_now = 0, size_goal;
 989         bool sg;
 990         long timeo;
 991
 992         lock_sock(sk);
 993
 994         flags = msg->msg_flags;
 995         timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 996
 997         /* Wait for a connection to finish. */
 998         if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
 999                 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
1000                         goto out_err;
1001
1002         if (unlikely(tp->repair)) {
1003                 if (tp->repair_queue == TCP_RECV_QUEUE) {
1004                         copied = tcp_send_rcvq(sk, msg, size);
1005                         goto out;
1006                 }
1007
1008                 err = -EINVAL;
1009                 if (tp->repair_queue == TCP_NO_QUEUE)
1010                         goto out_err;
1011
1012                 /* 'common' sending to sendq */
1013         }
1014
1015         /* This should be in poll */
1016         clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
1017
1018         mss_now = tcp_send_mss(sk, &size_goal, flags);
1019
1020         /* Ok commence sending. */
1021         iovlen = msg->msg_iovlen;
1022         iov = msg->msg_iov;
1023         copied = 0;
1024
1025         err = -EPIPE;
1026         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
1027                 goto out_err;
1028
1029         sg = !!(sk->sk_route_caps & NETIF_F_SG);
1030
1031         while (--iovlen >= 0) {
1032                 size_t seglen = iov->iov_len;
1033                 unsigned char __user *from = iov->iov_base;
1034
1035                 iov++;
1036
1037                 while (seglen > 0) {
1038                         int copy = 0;
1039                         int max = size_goal;
1040
1041                         skb = tcp_write_queue_tail(sk);
1042                         if (tcp_send_head(sk)) {
1043                                 if (skb->ip_summed == CHECKSUM_NONE)
1044                                         max = mss_now;
1045                                 copy = max - skb->len;
1046                         }
1047
1048                         if (copy <= 0) {
1049 new_segment:
1050                                 /* Allocate new segment. If the interface is SG,
1051                                  * allocate skb fitting to single page.
1052                                  */
1053                                 if (!sk_stream_memory_free(sk))
1054                                         goto wait_for_sndbuf;
1055
1056                                 skb = sk_stream_alloc_skb(sk,
1057                                                           select_size(sk, sg),
1058                                                           sk->sk_allocation);
1059                                 if (!skb)
1060                                         goto wait_for_memory;
1061
1062                                 /*
1063                                  * Check whether we can use HW checksum.
1064                                  */
1065                                 if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
1066                                         skb->ip_summed = CHECKSUM_PARTIAL;
1067
1068                                 skb_entail(sk, skb);
1069                                 copy = size_goal;
1070                                 max = size_goal;
1071                         }
1072
1073                         /* Try to append data to the end of skb. */
1074                         if (copy > seglen)
1075                                 copy = seglen;
1076
1077                         /* Where to copy to? */
1078                         if (skb_availroom(skb) > 0) {
1079                                 /* We have some space in skb head. Superb! */
1080                                 copy = min_t(int, copy, skb_availroom(skb));
1081                                 err = skb_add_data_nocache(sk, skb, from, copy);
1082                                 if (err)
1083                                         goto do_fault;
1084                         } else {
1085                                 bool merge = false;
1086                                 int i = skb_shinfo(skb)->nr_frags;
1087                                 struct page *page = sk->sk_sndmsg_page;
1088                                 int off;
1089
1090                                 if (page && page_count(page) == 1)
1091                                         sk->sk_sndmsg_off = 0;
1092
1093                                 off = sk->sk_sndmsg_off;
1094
1095                                 if (skb_can_coalesce(skb, i, page, off) &&
1096                                     off != PAGE_SIZE) {
1097                                         /* We can extend the last page
1098                                          * fragment. */
1099                                         merge = true;
1100                                 } else if (i == MAX_SKB_FRAGS || !sg) {
1101                                         /* Need to add new fragment and cannot
1102                                          * do this because interface is non-SG,
1103                                          * or because all the page slots are
1104                                          * busy. */
1105                                         tcp_mark_push(tp, skb);
1106                                         goto new_segment;
1107                                 } else if (page) {
1108                                         if (off == PAGE_SIZE) {
1109                                                 put_page(page);
1110                                                 sk->sk_sndmsg_page = page = NULL;
1111                                                 off = 0;
1112                                         }
1113                                 } else
1114                                         off = 0;
1115
1116                                 if (copy > PAGE_SIZE - off)
1117                                         copy = PAGE_SIZE - off;
1118
1119                                 if (!sk_wmem_schedule(sk, copy))
1120                                         goto wait_for_memory;
1121
1122                                 if (!page) {
1123                                         /* Allocate new cache page. */
1124                                         if (!(page = sk_stream_alloc_page(sk)))
1125                                                 goto wait_for_memory;
1126                                 }
1127
1128                                 /* Time to copy data. We are close to
1129                                  * the end! */
1130                                 err = skb_copy_to_page_nocache(sk, from, skb,
1131                                                                page, off, copy);
1132                                 if (err) {
1133                                         /* If this page was new, give it to the
1134                                          * socket so it does not get leaked.
1135                                          */
1136                                         if (!sk->sk_sndmsg_page) {
1137                                                 sk->sk_sndmsg_page = page;
1138                                                 sk->sk_sndmsg_off = 0;
1139                                         }
1140                                         goto do_error;
1141                                 }
1142
1143                                 /* Update the skb. */
1144                                 if (merge) {
1145                                         skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1146                                 } else {
1147                                         skb_fill_page_desc(skb, i, page, off, copy);
1148                                         if (sk->sk_sndmsg_page) {
1149                                                 get_page(page);
1150                                         } else if (off + copy < PAGE_SIZE) {
1151                                                 get_page(page);
1152                                                 sk->sk_sndmsg_page = page;
1153                                         }
1154                                 }
1155
1156                                 sk->sk_sndmsg_off = off + copy;
1157                         }
1158
1159                         if (!copied)
1160                                 TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
1161
1162                         tp->write_seq += copy;
1163                         TCP_SKB_CB(skb)->end_seq += copy;
1164                         skb_shinfo(skb)->gso_segs = 0;
1165
1166                         from += copy;
1167                         copied += copy;
1168                         if ((seglen -= copy) == 0 && iovlen == 0)
1169                                 goto out;
1170
1171                         if (skb->len < max || (flags & MSG_OOB) || unlikely(tp->repair))
1172                                 continue;
1173
1174                         if (forced_push(tp)) {
1175                                 tcp_mark_push(tp, skb);
1176                                 __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
1177                         } else if (skb == tcp_send_head(sk))
1178                                 tcp_push_one(sk, mss_now);
1179                         continue;
1180
1181 wait_for_sndbuf:
1182                         set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
1183 wait_for_memory:
1184                         if (copied && likely(!tp->repair))
1185                                 tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
1186
1187                         if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
1188                                 goto do_error;
1189
1190                         mss_now = tcp_send_mss(sk, &size_goal, flags);
1191                 }
1192         }
1193
1194 out:
1195         if (copied && likely(!tp->repair))
1196                 tcp_push(sk, flags, mss_now, tp->nonagle);
1197         release_sock(sk);
1198         return copied;
1199
1200 do_fault:
1201         if (!skb->len) {
1202                 tcp_unlink_write_queue(skb, sk);
1203                 /* It is the one place in all of TCP, except connection
1204                  * reset, where we can be unlinking the send_head.
1205                  */
1206                 tcp_check_send_head(sk, skb);
1207                 sk_wmem_free_skb(sk, skb);
1208         }
1209
1210 do_error:
1211         if (copied)
1212                 goto out;
1213 out_err:
1214         err = sk_stream_error(sk, flags, err);
1215         release_sock(sk);
1216         return err;
1217 }
1218 EXPORT_SYMBOL(tcp_sendmsg);
1219
1220 /*
1221  *      Handle reading urgent data. BSD has very simple semantics for
1222  *      this, no blocking and very strange errors 8)
1223  */
1224
1225 static int tcp_recv_urg(struct sock *sk, struct msghdr *msg, int len, int flags)
1226 {
1227         struct tcp_sock *tp = tcp_sk(sk);
1228
1229         /* No URG data to read. */
1230         if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
1231             tp->urg_data == TCP_URG_READ)
1232                 return -EINVAL; /* Yes this is right ! */
1233
1234         if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
1235                 return -ENOTCONN;
1236
1237         if (tp->urg_data & TCP_URG_VALID) {
1238                 int err = 0;
1239                 char c = tp->urg_data;
1240
1241                 if (!(flags & MSG_PEEK))
1242                         tp->urg_data = TCP_URG_READ;
1243
1244                 /* Read urgent data. */
1245                 msg->msg_flags |= MSG_OOB;
1246
1247                 if (len > 0) {
1248                         if (!(flags & MSG_TRUNC))
1249                                 err = memcpy_toiovec(msg->msg_iov, &c, 1);
1250                         len = 1;
1251                 } else
1252                         msg->msg_flags |= MSG_TRUNC;
1253
1254                 return err ? -EFAULT : len;
1255         }
1256
1257         if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
1258                 return 0;
1259
1260         /* Fixed the recv(..., MSG_OOB) behaviour.  BSD docs and
1261          * the available implementations agree in this case:
1262          * this call should never block, independent of the
1263          * blocking state of the socket.
1264          * Mike <pall@rz.uni-karlsruhe.de>
1265          */
1266         return -EAGAIN;
1267 }
1268
1269 static int tcp_peek_sndq(struct sock *sk, struct msghdr *msg, int len)
1270 {
1271         struct sk_buff *skb;
1272         int copied = 0, err = 0;
1273
1274         /* XXX -- need to support SO_PEEK_OFF */
1275
1276         skb_queue_walk(&sk->sk_write_queue, skb) {
1277                 err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, skb->len);
1278                 if (err)
1279                         break;
1280
1281                 copied += skb->len;
1282         }
1283
1284         return err ?: copied;
1285 }
1286
1287 /* Clean up the receive buffer for full frames taken by the user,
1288  * then send an ACK if necessary.  COPIED is the number of bytes
1289  * tcp_recvmsg has given to the user so far, it speeds up the
1290  * calculation of whether or not we must ACK for the sake of
1291  * a window update.
1292  */
1293 void tcp_cleanup_rbuf(struct sock *sk, int copied)
1294 {
1295         struct tcp_sock *tp = tcp_sk(sk);
1296         bool time_to_ack = false;
1297
1298         struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
1299
1300         WARN(skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq),
1301              "cleanup rbuf bug: copied %X seq %X rcvnxt %X\n",
1302              tp->copied_seq, TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt);
1303
1304         if (inet_csk_ack_scheduled(sk)) {
1305                 const struct inet_connection_sock *icsk = inet_csk(sk);
1306                    /* Delayed ACKs frequently hit locked sockets during bulk
1307                     * receive. */
1308                 if (icsk->icsk_ack.blocked ||
1309                     /* Once-per-two-segments ACK was not sent by tcp_input.c */
1310                     tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
1311                     /*
1312                      * If this read emptied read buffer, we send ACK, if
1313                      * connection is not bidirectional, user drained
1314                      * receive buffer and there was a small segment
1315                      * in queue.
1316                      */
1317                     (copied > 0 &&
1318                      ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) ||
1319                       ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
1320                        !icsk->icsk_ack.pingpong)) &&
1321                       !atomic_read(&sk->sk_rmem_alloc)))
1322                         time_to_ack = true;
1323         }
1324
1325         /* We send an ACK if we can now advertise a non-zero window
1326          * which has been raised "significantly".
1327          *
1328          * Even if window raised up to infinity, do not send window open ACK
1329          * in states, where we will not receive more. It is useless.
1330          */
1331         if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
1332                 __u32 rcv_window_now = tcp_receive_window(tp);
1333
1334                 /* Optimize, __tcp_select_window() is not cheap. */
1335                 if (2*rcv_window_now <= tp->window_clamp) {
1336                         __u32 new_window = __tcp_select_window(sk);
1337
1338                         /* Send ACK now, if this read freed lots of space
1339                          * in our buffer. Certainly, new_window is new window.
1340                          * We can advertise it now, if it is not less than current one.
1341                          * "Lots" means "at least twice" here.
1342                          */
1343                         if (new_window && new_window >= 2 * rcv_window_now)
1344                                 time_to_ack = true;
1345                 }
1346         }
1347         if (time_to_ack)
1348                 tcp_send_ack(sk);
1349 }
1350
1351 static void tcp_prequeue_process(struct sock *sk)
1352 {
1353         struct sk_buff *skb;
1354         struct tcp_sock *tp = tcp_sk(sk);
1355
1356         NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPPREQUEUED);
1357
1358         /* RX process wants to run with disabled BHs, though it is not
1359          * necessary */
1360         local_bh_disable();
1361         while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)
1362                 sk_backlog_rcv(sk, skb);
1363         local_bh_enable();
1364
1365         /* Clear memory counter. */
1366         tp->ucopy.memory = 0;
1367 }
1368
1369 #ifdef CONFIG_NET_DMA
1370 static void tcp_service_net_dma(struct sock *sk, bool wait)
1371 {
1372         dma_cookie_t done, used;
1373         dma_cookie_t last_issued;
1374         struct tcp_sock *tp = tcp_sk(sk);
1375
1376         if (!tp->ucopy.dma_chan)
1377                 return;
1378
1379         last_issued = tp->ucopy.dma_cookie;
1380         dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
1381
1382         do {
1383                 if (dma_async_memcpy_complete(tp->ucopy.dma_chan,
1384                                               last_issued, &done,
1385                                               &used) == DMA_SUCCESS) {
1386                         /* Safe to free early-copied skbs now */
1387                         __skb_queue_purge(&sk->sk_async_wait_queue);
1388                         break;
1389                 } else {
1390                         struct sk_buff *skb;
1391                         while ((skb = skb_peek(&sk->sk_async_wait_queue)) &&
1392                                (dma_async_is_complete(skb->dma_cookie, done,
1393                                                       used) == DMA_SUCCESS)) {
1394                                 __skb_dequeue(&sk->sk_async_wait_queue);
1395                                 kfree_skb(skb);
1396                         }
1397                 }
1398         } while (wait);
1399 }
1400 #endif
1401
1402 static inline struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
1403 {
1404         struct sk_buff *skb;
1405         u32 offset;
1406
1407         skb_queue_walk(&sk->sk_receive_queue, skb) {
1408                 offset = seq - TCP_SKB_CB(skb)->seq;
1409                 if (tcp_hdr(skb)->syn)
1410                         offset--;
1411                 if (offset < skb->len || tcp_hdr(skb)->fin) {
1412                         *off = offset;
1413                         return skb;
1414                 }
1415         }
1416         return NULL;
1417 }
1418
1419 /*
1420  * This routine provides an alternative to tcp_recvmsg() for routines
1421  * that would like to handle copying from skbuffs directly in 'sendfile'
1422  * fashion.
1423  * Note:
1424  *      - It is assumed that the socket was locked by the caller.
1425  *      - The routine does not block.
1426  *      - At present, there is no support for reading OOB data
1427  *        or for 'peeking' the socket using this routine
1428  *        (although both would be easy to implement).
1429  */
1430 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
1431                   sk_read_actor_t recv_actor)
1432 {
1433         struct sk_buff *skb;
1434         struct tcp_sock *tp = tcp_sk(sk);
1435         u32 seq = tp->copied_seq;
1436         u32 offset;
1437         int copied = 0;
1438
1439         if (sk->sk_state == TCP_LISTEN)
1440                 return -ENOTCONN;
1441         while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
1442                 if (offset < skb->len) {
1443                         int used;
1444                         size_t len;
1445
1446                         len = skb->len - offset;
1447                         /* Stop reading if we hit a patch of urgent data */
1448                         if (tp->urg_data) {
1449                                 u32 urg_offset = tp->urg_seq - seq;
1450                                 if (urg_offset < len)
1451                                         len = urg_offset;
1452                                 if (!len)
1453                                         break;
1454                         }
1455                         used = recv_actor(desc, skb, offset, len);
1456                         if (used < 0) {
1457                                 if (!copied)
1458                                         copied = used;
1459                                 break;
1460                         } else if (used <= len) {
1461                                 seq += used;
1462                                 copied += used;
1463                                 offset += used;
1464                         }
1465                         /*
1466                          * If recv_actor drops the lock (e.g. TCP splice
1467                          * receive) the skb pointer might be invalid when
1468                          * getting here: tcp_collapse might have deleted it
1469                          * while aggregating skbs from the socket queue.
1470                          */
1471                         skb = tcp_recv_skb(sk, seq-1, &offset);
1472                         if (!skb || (offset+1 != skb->len))
1473                                 break;
1474                 }
1475                 if (tcp_hdr(skb)->fin) {
1476                         sk_eat_skb(sk, skb, false);
1477                         ++seq;
1478                         break;
1479                 }
1480                 sk_eat_skb(sk, skb, false);
1481                 if (!desc->count)
1482                         break;
1483                 tp->copied_seq = seq;
1484         }
1485         tp->copied_seq = seq;
1486
1487         tcp_rcv_space_adjust(sk);
1488
1489         /* Clean up data we have read: This will do ACK frames. */
1490         if (copied > 0)
1491                 tcp_cleanup_rbuf(sk, copied);
1492         return copied;
1493 }
1494 EXPORT_SYMBOL(tcp_read_sock);
1495
1496 /*
1497  *      This routine copies from a sock struct into the user buffer.
1498  *
1499  *      Technical note: in 2.3 we work on _locked_ socket, so that
1500  *      tricks with *seq access order and skb->users are not required.
1501  *      Probably, code can be easily improved even more.
1502  */
1503
1504 int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
1505                 size_t len, int nonblock, int flags, int *addr_len)
1506 {
1507         struct tcp_sock *tp = tcp_sk(sk);
1508         int copied = 0;
1509         u32 peek_seq;
1510         u32 *seq;
1511         unsigned long used;
1512         int err;
1513         int target;             /* Read at least this many bytes */
1514         long timeo;
1515         struct task_struct *user_recv = NULL;
1516         bool copied_early = false;
1517         struct sk_buff *skb;
1518         u32 urg_hole = 0;
1519
1520         lock_sock(sk);
1521
1522         err = -ENOTCONN;
1523         if (sk->sk_state == TCP_LISTEN)
1524                 goto out;
1525
1526         timeo = sock_rcvtimeo(sk, nonblock);
1527
1528         /* Urgent data needs to be handled specially. */
1529         if (flags & MSG_OOB)
1530                 goto recv_urg;
1531
1532         if (unlikely(tp->repair)) {
1533                 err = -EPERM;
1534                 if (!(flags & MSG_PEEK))
1535                         goto out;
1536
1537                 if (tp->repair_queue == TCP_SEND_QUEUE)
1538                         goto recv_sndq;
1539
1540                 err = -EINVAL;
1541                 if (tp->repair_queue == TCP_NO_QUEUE)
1542                         goto out;
1543
1544                 /* 'common' recv queue MSG_PEEK-ing */
1545         }
1546
1547         seq = &tp->copied_seq;
1548         if (flags & MSG_PEEK) {
1549                 peek_seq = tp->copied_seq;
1550                 seq = &peek_seq;
1551         }
1552
1553         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
1554
1555 #ifdef CONFIG_NET_DMA
1556         tp->ucopy.dma_chan = NULL;
1557         preempt_disable();
1558         skb = skb_peek_tail(&sk->sk_receive_queue);
1559         {
1560                 int available = 0;
1561
1562                 if (skb)
1563                         available = TCP_SKB_CB(skb)->seq + skb->len - (*seq);
1564                 if ((available < target) &&
1565                     (len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) &&
1566                     !sysctl_tcp_low_latency &&
1567                     net_dma_find_channel()) {
1568                         preempt_enable_no_resched();
1569                         tp->ucopy.pinned_list =
1570                                         dma_pin_iovec_pages(msg->msg_iov, len);
1571                 } else {
1572                         preempt_enable_no_resched();
1573                 }
1574         }
1575 #endif
1576
1577         do {
1578                 u32 offset;
1579
1580                 /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
1581                 if (tp->urg_data && tp->urg_seq == *seq) {
1582                         if (copied)
1583                                 break;
1584                         if (signal_pending(current)) {
1585                                 copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
1586                                 break;
1587                         }
1588                 }
1589
1590                 /* Next get a buffer. */
1591
1592                 skb_queue_walk(&sk->sk_receive_queue, skb) {
1593                         /* Now that we have two receive queues this
1594                          * shouldn't happen.
1595                          */
1596                         if (WARN(before(*seq, TCP_SKB_CB(skb)->seq),
1597                                  "recvmsg bug: copied %X seq %X rcvnxt %X fl %X\n",
1598                                  *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt,
1599                                  flags))
1600                                 break;
1601
1602                         offset = *seq - TCP_SKB_CB(skb)->seq;
1603                         if (tcp_hdr(skb)->syn)
1604                                 offset--;
1605                         if (offset < skb->len)
1606                                 goto found_ok_skb;
1607                         if (tcp_hdr(skb)->fin)
1608                                 goto found_fin_ok;
1609                         WARN(!(flags & MSG_PEEK),
1610                              "recvmsg bug 2: copied %X seq %X rcvnxt %X fl %X\n",
1611                              *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt, flags);
1612                 }
1613
1614                 /* Well, if we have backlog, try to process it now yet. */
1615
1616                 if (copied >= target && !sk->sk_backlog.tail)
1617                         break;
1618
1619                 if (copied) {
1620                         if (sk->sk_err ||
1621                             sk->sk_state == TCP_CLOSE ||
1622                             (sk->sk_shutdown & RCV_SHUTDOWN) ||
1623                             !timeo ||
1624                             signal_pending(current))
1625                                 break;
1626                 } else {
1627                         if (sock_flag(sk, SOCK_DONE))
1628                                 break;
1629
1630                         if (sk->sk_err) {
1631                                 copied = sock_error(sk);
1632                                 break;
1633                         }
1634
1635                         if (sk->sk_shutdown & RCV_SHUTDOWN)
1636                                 break;
1637
1638                         if (sk->sk_state == TCP_CLOSE) {
1639                                 if (!sock_flag(sk, SOCK_DONE)) {
1640                                         /* This occurs when user tries to read
1641                                          * from never connected socket.
1642                                          */
1643                                         copied = -ENOTCONN;
1644                                         break;
1645                                 }
1646                                 break;
1647                         }
1648
1649                         if (!timeo) {
1650                                 copied = -EAGAIN;
1651                                 break;
1652                         }
1653
1654                         if (signal_pending(current)) {
1655                                 copied = sock_intr_errno(timeo);
1656                                 break;
1657                         }
1658                 }
1659
1660                 tcp_cleanup_rbuf(sk, copied);
1661
1662                 if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) {
1663                         /* Install new reader */
1664                         if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) {
1665                                 user_recv = current;
1666                                 tp->ucopy.task = user_recv;
1667                                 tp->ucopy.iov = msg->msg_iov;
1668                         }
1669
1670                         tp->ucopy.len = len;
1671
1672                         WARN_ON(tp->copied_seq != tp->rcv_nxt &&
1673                                 !(flags & (MSG_PEEK | MSG_TRUNC)));
1674
1675                         /* Ugly... If prequeue is not empty, we have to
1676                          * process it before releasing socket, otherwise
1677                          * order will be broken at second iteration.
1678                          * More elegant solution is required!!!
1679                          *
1680                          * Look: we have the following (pseudo)queues:
1681                          *
1682                          * 1. packets in flight
1683                          * 2. backlog
1684                          * 3. prequeue
1685                          * 4. receive_queue
1686                          *
1687                          * Each queue can be processed only if the next ones
1688                          * are empty. At this point we have empty receive_queue.
1689                          * But prequeue _can_ be not empty after 2nd iteration,
1690                          * when we jumped to start of loop because backlog
1691                          * processing added something to receive_queue.
1692                          * We cannot release_sock(), because backlog contains
1693                          * packets arrived _after_ prequeued ones.
1694                          *
1695                          * Shortly, algorithm is clear --- to process all
1696                          * the queues in order. We could make it more directly,
1697                          * requeueing packets from backlog to prequeue, if
1698                          * is not empty. It is more elegant, but eats cycles,
1699                          * unfortunately.
1700                          */
1701                         if (!skb_queue_empty(&tp->ucopy.prequeue))
1702                                 goto do_prequeue;
1703
1704                         /* __ Set realtime policy in scheduler __ */
1705                 }
1706
1707 #ifdef CONFIG_NET_DMA
1708                 if (tp->ucopy.dma_chan)
1709                         dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
1710 #endif
1711                 if (copied >= target) {
1712                         /* Do not sleep, just process backlog. */
1713                         release_sock(sk);
1714                         lock_sock(sk);
1715                 } else
1716                         sk_wait_data(sk, &timeo);
1717
1718 #ifdef CONFIG_NET_DMA
1719                 tcp_service_net_dma(sk, false);  /* Don't block */
1720                 tp->ucopy.wakeup = 0;
1721 #endif
1722
1723                 if (user_recv) {
1724                         int chunk;
1725
1726                         /* __ Restore normal policy in scheduler __ */
1727
1728                         if ((chunk = len - tp->ucopy.len) != 0) {
1729                                 NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk);
1730                                 len -= chunk;
1731                                 copied += chunk;
1732                         }
1733
1734                         if (tp->rcv_nxt == tp->copied_seq &&
1735                             !skb_queue_empty(&tp->ucopy.prequeue)) {
1736 do_prequeue:
1737                                 tcp_prequeue_process(sk);
1738
1739                                 if ((chunk = len - tp->ucopy.len) != 0) {
1740                                         NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1741                                         len -= chunk;
1742                                         copied += chunk;
1743                                 }
1744                         }
1745                 }
1746                 if ((flags & MSG_PEEK) &&
1747                     (peek_seq - copied - urg_hole != tp->copied_seq)) {
1748                         net_dbg_ratelimited("TCP(%s:%d): Application bug, race in MSG_PEEK\n",
1749                                             current->comm,
1750                                             task_pid_nr(current));
1751                         peek_seq = tp->copied_seq;
1752                 }
1753                 continue;
1754
1755         found_ok_skb:
1756                 /* Ok so how much can we use? */
1757                 used = skb->len - offset;
1758                 if (len < used)
1759                         used = len;
1760
1761                 /* Do we have urgent data here? */
1762                 if (tp->urg_data) {
1763                         u32 urg_offset = tp->urg_seq - *seq;
1764                         if (urg_offset < used) {
1765                                 if (!urg_offset) {
1766                                         if (!sock_flag(sk, SOCK_URGINLINE)) {
1767                                                 ++*seq;
1768                                                 urg_hole++;
1769                                                 offset++;
1770                                                 used--;
1771                                                 if (!used)
1772                                                         goto skip_copy;
1773                                         }
1774                                 } else
1775                                         used = urg_offset;
1776                         }
1777                 }
1778
1779                 if (!(flags & MSG_TRUNC)) {
1780 #ifdef CONFIG_NET_DMA
1781                         if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1782                                 tp->ucopy.dma_chan = net_dma_find_channel();
1783
1784                         if (tp->ucopy.dma_chan) {
1785                                 tp->ucopy.dma_cookie = dma_skb_copy_datagram_iovec(
1786                                         tp->ucopy.dma_chan, skb, offset,
1787                                         msg->msg_iov, used,
1788                                         tp->ucopy.pinned_list);
1789
1790                                 if (tp->ucopy.dma_cookie < 0) {
1791
1792                                         pr_alert("%s: dma_cookie < 0\n",
1793                                                  __func__);
1794
1795                                         /* Exception. Bailout! */
1796                                         if (!copied)
1797                                                 copied = -EFAULT;
1798                                         break;
1799                                 }
1800
1801                                 dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
1802
1803                                 if ((offset + used) == skb->len)
1804                                         copied_early = true;
1805
1806                         } else
1807 #endif
1808                         {
1809                                 err = skb_copy_datagram_iovec(skb, offset,
1810                                                 msg->msg_iov, used);
1811                                 if (err) {
1812                                         /* Exception. Bailout! */
1813                                         if (!copied)
1814                                                 copied = -EFAULT;
1815                                         break;
1816                                 }
1817                         }
1818                 }
1819
1820                 *seq += used;
1821                 copied += used;
1822                 len -= used;
1823
1824                 tcp_rcv_space_adjust(sk);
1825
1826 skip_copy:
1827                 if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) {
1828                         tp->urg_data = 0;
1829                         tcp_fast_path_check(sk);
1830                 }
1831                 if (used + offset < skb->len)
1832                         continue;
1833
1834                 if (tcp_hdr(skb)->fin)
1835                         goto found_fin_ok;
1836                 if (!(flags & MSG_PEEK)) {
1837                         sk_eat_skb(sk, skb, copied_early);
1838                         copied_early = false;
1839                 }
1840                 continue;
1841
1842         found_fin_ok:
1843                 /* Process the FIN. */
1844                 ++*seq;
1845                 if (!(flags & MSG_PEEK)) {
1846                         sk_eat_skb(sk, skb, copied_early);
1847                         copied_early = false;
1848                 }
1849                 break;
1850         } while (len > 0);
1851
1852         if (user_recv) {
1853                 if (!skb_queue_empty(&tp->ucopy.prequeue)) {
1854                         int chunk;
1855
1856                         tp->ucopy.len = copied > 0 ? len : 0;
1857
1858                         tcp_prequeue_process(sk);
1859
1860                         if (copied > 0 && (chunk = len - tp->ucopy.len) != 0) {
1861                                 NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1862                                 len -= chunk;
1863                                 copied += chunk;
1864                         }
1865                 }
1866
1867                 tp->ucopy.task = NULL;
1868                 tp->ucopy.len = 0;
1869         }
1870
1871 #ifdef CONFIG_NET_DMA
1872         tcp_service_net_dma(sk, true);  /* Wait for queue to drain */
1873         tp->ucopy.dma_chan = NULL;
1874
1875         if (tp->ucopy.pinned_list) {
1876                 dma_unpin_iovec_pages(tp->ucopy.pinned_list);
1877                 tp->ucopy.pinned_list = NULL;
1878         }
1879 #endif
1880
1881         /* According to UNIX98, msg_name/msg_namelen are ignored
1882          * on connected socket. I was just happy when found this 8) --ANK
1883          */
1884
1885         /* Clean up data we have read: This will do ACK frames. */
1886         tcp_cleanup_rbuf(sk, copied);
1887
1888         release_sock(sk);
1889         return copied;
1890
1891 out:
1892         release_sock(sk);
1893         return err;
1894
1895 recv_urg:
1896         err = tcp_recv_urg(sk, msg, len, flags);
1897         goto out;
1898
1899 recv_sndq:
1900         err = tcp_peek_sndq(sk, msg, len);
1901         goto out;
1902 }
1903 EXPORT_SYMBOL(tcp_recvmsg);
1904
1905 void tcp_set_state(struct sock *sk, int state)
1906 {
1907         int oldstate = sk->sk_state;
1908
1909         switch (state) {
1910         case TCP_ESTABLISHED:
1911                 if (oldstate != TCP_ESTABLISHED)
1912                         TCP_INC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1913                 break;
1914
1915         case TCP_CLOSE:
1916                 if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
1917                         TCP_INC_STATS(sock_net(sk), TCP_MIB_ESTABRESETS);
1918
1919                 sk->sk_prot->unhash(sk);
1920                 if (inet_csk(sk)->icsk_bind_hash &&
1921                     !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
1922                         inet_put_port(sk);
1923                 /* fall through */
1924         default:
1925                 if (oldstate == TCP_ESTABLISHED)
1926                         TCP_DEC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1927         }
1928
1929         /* Change state AFTER socket is unhashed to avoid closed
1930          * socket sitting in hash tables.
1931          */
1932         sk->sk_state = state;
1933
1934 #ifdef STATE_TRACE
1935         SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n", sk, statename[oldstate], statename[state]);
1936 #endif
1937 }
1938 EXPORT_SYMBOL_GPL(tcp_set_state);
1939
1940 /*
1941  *      State processing on a close. This implements the state shift for
1942  *      sending our FIN frame. Note that we only send a FIN for some
1943  *      states. A shutdown() may have already sent the FIN, or we may be
1944  *      closed.
1945  */
1946
1947 static const unsigned char new_state[16] = {
1948   /* current state:        new state:      action:      */
1949   /* (Invalid)          */ TCP_CLOSE,
1950   /* TCP_ESTABLISHED    */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1951   /* TCP_SYN_SENT       */ TCP_CLOSE,
1952   /* TCP_SYN_RECV       */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1953   /* TCP_FIN_WAIT1      */ TCP_FIN_WAIT1,
1954   /* TCP_FIN_WAIT2      */ TCP_FIN_WAIT2,
1955   /* TCP_TIME_WAIT      */ TCP_CLOSE,
1956   /* TCP_CLOSE          */ TCP_CLOSE,
1957   /* TCP_CLOSE_WAIT     */ TCP_LAST_ACK  | TCP_ACTION_FIN,
1958   /* TCP_LAST_ACK       */ TCP_LAST_ACK,
1959   /* TCP_LISTEN         */ TCP_CLOSE,
1960   /* TCP_CLOSING        */ TCP_CLOSING,
1961 };
1962
1963 static int tcp_close_state(struct sock *sk)
1964 {
1965         int next = (int)new_state[sk->sk_state];
1966         int ns = next & TCP_STATE_MASK;
1967
1968         tcp_set_state(sk, ns);
1969
1970         return next & TCP_ACTION_FIN;
1971 }
1972
1973 /*
1974  *      Shutdown the sending side of a connection. Much like close except
1975  *      that we don't receive shut down or sock_set_flag(sk, SOCK_DEAD).
1976  */
1977
1978 void tcp_shutdown(struct sock *sk, int how)
1979 {
1980         /*      We need to grab some memory, and put together a FIN,
1981          *      and then put it into the queue to be sent.
1982          *              Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
1983          */
1984         if (!(how & SEND_SHUTDOWN))
1985                 return;
1986
1987         /* If we've already sent a FIN, or it's a closed state, skip this. */
1988         if ((1 << sk->sk_state) &
1989             (TCPF_ESTABLISHED | TCPF_SYN_SENT |
1990              TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
1991                 /* Clear out any half completed packets.  FIN if needed. */
1992                 if (tcp_close_state(sk))
1993                         tcp_send_fin(sk);
1994         }
1995 }
1996 EXPORT_SYMBOL(tcp_shutdown);
1997
1998 bool tcp_check_oom(struct sock *sk, int shift)
1999 {
2000         bool too_many_orphans, out_of_socket_memory;
2001
2002         too_many_orphans = tcp_too_many_orphans(sk, shift);
2003         out_of_socket_memory = tcp_out_of_memory(sk);
2004
2005         if (too_many_orphans)
2006                 net_info_ratelimited("too many orphaned sockets\n");
2007         if (out_of_socket_memory)
2008                 net_info_ratelimited("out of memory -- consider tuning tcp_mem\n");
2009         return too_many_orphans || out_of_socket_memory;
2010 }
2011
2012 void tcp_close(struct sock *sk, long timeout)
2013 {
2014         struct sk_buff *skb;
2015         int data_was_unread = 0;
2016         int state;
2017
2018         lock_sock(sk);
2019         sk->sk_shutdown = SHUTDOWN_MASK;
2020
2021         if (sk->sk_state == TCP_LISTEN) {
2022                 tcp_set_state(sk, TCP_CLOSE);
2023
2024                 /* Special case. */
2025                 inet_csk_listen_stop(sk);
2026
2027                 goto adjudge_to_death;
2028         }
2029
2030         /*  We need to flush the recv. buffs.  We do this only on the
2031          *  descriptor close, not protocol-sourced closes, because the
2032          *  reader process may not have drained the data yet!
2033          */
2034         while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
2035                 u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq -
2036                           tcp_hdr(skb)->fin;
2037                 data_was_unread += len;
2038                 __kfree_skb(skb);
2039         }
2040
2041         sk_mem_reclaim(sk);
2042
2043         /* If socket has been already reset (e.g. in tcp_reset()) - kill it. */
2044         if (sk->sk_state == TCP_CLOSE)
2045                 goto adjudge_to_death;
2046
2047         /* As outlined in RFC 2525, section 2.17, we send a RST here because
2048          * data was lost. To witness the awful effects of the old behavior of
2049          * always doing a FIN, run an older 2.1.x kernel or 2.0.x, start a bulk
2050          * GET in an FTP client, suspend the process, wait for the client to
2051          * advertise a zero window, then kill -9 the FTP client, wheee...
2052          * Note: timeout is always zero in such a case.
2053          */
2054         if (unlikely(tcp_sk(sk)->repair)) {
2055                 sk->sk_prot->disconnect(sk, 0);
2056         } else if (data_was_unread) {
2057                 /* Unread data was tossed, zap the connection. */
2058                 NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPABORTONCLOSE);
2059                 tcp_set_state(sk, TCP_CLOSE);
2060                 tcp_send_active_reset(sk, sk->sk_allocation);
2061         } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
2062                 /* Check zero linger _after_ checking for unread data. */
2063                 sk->sk_prot->disconnect(sk, 0);
2064                 NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
2065         } else if (tcp_close_state(sk)) {
2066                 /* We FIN if the application ate all the data before
2067                  * zapping the connection.
2068                  */
2069
2070                 /* RED-PEN. Formally speaking, we have broken TCP state
2071                  * machine. State transitions:
2072                  *
2073                  * TCP_ESTABLISHED -> TCP_FIN_WAIT1
2074                  * TCP_SYN_RECV -> TCP_FIN_WAIT1 (forget it, it's impossible)
2075                  * TCP_CLOSE_WAIT -> TCP_LAST_ACK
2076                  *
2077                  * are legal only when FIN has been sent (i.e. in window),
2078                  * rather than queued out of window. Purists blame.
2079                  *
2080                  * F.e. "RFC state" is ESTABLISHED,
2081                  * if Linux state is FIN-WAIT-1, but FIN is still not sent.
2082                  *
2083                  * The visible declinations are that sometimes
2084                  * we enter time-wait state, when it is not required really
2085                  * (harmless), do not send active resets, when they are
2086                  * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when
2087                  * they look as CLOSING or LAST_ACK for Linux)
2088                  * Probably, I missed some more holelets.
2089                  *                                              --ANK
2090                  */
2091                 tcp_send_fin(sk);
2092         }
2093
2094         sk_stream_wait_close(sk, timeout);
2095
2096 adjudge_to_death:
2097         state = sk->sk_state;
2098         sock_hold(sk);
2099         sock_orphan(sk);
2100
2101         /* It is the last release_sock in its life. It will remove backlog. */
2102         release_sock(sk);
2103
2104
2105         /* Now socket is owned by kernel and we acquire BH lock
2106            to finish close. No need to check for user refs.
2107          */
2108         local_bh_disable();
2109         bh_lock_sock(sk);
2110         WARN_ON(sock_owned_by_user(sk));
2111
2112         percpu_counter_inc(sk->sk_prot->orphan_count);
2113
2114         /* Have we already been destroyed by a softirq or backlog? */
2115         if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
2116                 goto out;
2117
2118         /*      This is a (useful) BSD violating of the RFC. There is a
2119          *      problem with TCP as specified in that the other end could
2120          *      keep a socket open forever with no application left this end.
2121          *      We use a 3 minute timeout (about the same as BSD) then kill
2122          *      our end. If they send after that then tough - BUT: long enough
2123          *      that we won't make the old 4*rto = almost no time - whoops
2124          *      reset mistake.
2125          *
2126          *      Nope, it was not mistake. It is really desired behaviour
2127          *      f.e. on http servers, when such sockets are useless, but
2128          *      consume significant resources. Let's do it with special
2129          *      linger2 option.                                 --ANK
2130          */
2131
2132         if (sk->sk_state == TCP_FIN_WAIT2) {
2133                 struct tcp_sock *tp = tcp_sk(sk);
2134                 if (tp->linger2 < 0) {
2135                         tcp_set_state(sk, TCP_CLOSE);
2136                         tcp_send_active_reset(sk, GFP_ATOMIC);
2137                         NET_INC_STATS_BH(sock_net(sk),
2138                                         LINUX_MIB_TCPABORTONLINGER);
2139                 } else {
2140                         const int tmo = tcp_fin_time(sk);
2141
2142                         if (tmo > TCP_TIMEWAIT_LEN) {
2143                                 inet_csk_reset_keepalive_timer(sk,
2144                                                 tmo - TCP_TIMEWAIT_LEN);
2145                         } else {
2146                                 tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
2147                                 goto out;
2148                         }
2149                 }
2150         }
2151         if (sk->sk_state != TCP_CLOSE) {
2152                 sk_mem_reclaim(sk);
2153                 if (tcp_check_oom(sk, 0)) {
2154                         tcp_set_state(sk, TCP_CLOSE);
2155                         tcp_send_active_reset(sk, GFP_ATOMIC);
2156                         NET_INC_STATS_BH(sock_net(sk),
2157                                         LINUX_MIB_TCPABORTONMEMORY);
2158                 }
2159         }
2160
2161         if (sk->sk_state == TCP_CLOSE)
2162                 inet_csk_destroy_sock(sk);
2163         /* Otherwise, socket is reprieved until protocol close. */
2164
2165 out:
2166         bh_unlock_sock(sk);
2167         local_bh_enable();
2168         sock_put(sk);
2169 }
2170 EXPORT_SYMBOL(tcp_close);
2171
2172 /* These states need RST on ABORT according to RFC793 */
2173
2174 static inline bool tcp_need_reset(int state)
2175 {
2176         return (1 << state) &
2177                (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
2178                 TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
2179 }
2180
2181 int tcp_disconnect(struct sock *sk, int flags)
2182 {
2183         struct inet_sock *inet = inet_sk(sk);
2184         struct inet_connection_sock *icsk = inet_csk(sk);
2185         struct tcp_sock *tp = tcp_sk(sk);
2186         int err = 0;
2187         int old_state = sk->sk_state;
2188
2189         if (old_state != TCP_CLOSE)
2190                 tcp_set_state(sk, TCP_CLOSE);
2191
2192         /* ABORT function of RFC793 */
2193         if (old_state == TCP_LISTEN) {
2194                 inet_csk_listen_stop(sk);
2195         } else if (unlikely(tp->repair)) {
2196                 sk->sk_err = ECONNABORTED;
2197         } else if (tcp_need_reset(old_state) ||
2198                    (tp->snd_nxt != tp->write_seq &&
2199                     (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
2200                 /* The last check adjusts for discrepancy of Linux wrt. RFC
2201                  * states
2202                  */
2203                 tcp_send_active_reset(sk, gfp_any());
2204                 sk->sk_err = ECONNRESET;
2205         } else if (old_state == TCP_SYN_SENT)
2206                 sk->sk_err = ECONNRESET;
2207
2208         tcp_clear_xmit_timers(sk);
2209         __skb_queue_purge(&sk->sk_receive_queue);
2210         tcp_write_queue_purge(sk);
2211         __skb_queue_purge(&tp->out_of_order_queue);
2212 #ifdef CONFIG_NET_DMA
2213         __skb_queue_purge(&sk->sk_async_wait_queue);
2214 #endif
2215
2216         inet->inet_dport = 0;
2217
2218         if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
2219                 inet_reset_saddr(sk);
2220
2221         sk->sk_shutdown = 0;
2222         sock_reset_flag(sk, SOCK_DONE);
2223         tp->srtt = 0;
2224         if ((tp->write_seq += tp->max_window + 2) == 0)
2225                 tp->write_seq = 1;
2226         icsk->icsk_backoff = 0;
2227         tp->snd_cwnd = 2;
2228         icsk->icsk_probes_out = 0;
2229         tp->packets_out = 0;
2230         tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
2231         tp->snd_cwnd_cnt = 0;
2232         tp->bytes_acked = 0;
2233         tp->window_clamp = 0;
2234         tcp_set_ca_state(sk, TCP_CA_Open);
2235         tcp_clear_retrans(tp);
2236         inet_csk_delack_init(sk);
2237         tcp_init_send_head(sk);
2238         memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
2239         __sk_dst_reset(sk);
2240
2241         WARN_ON(inet->inet_num && !icsk->icsk_bind_hash);
2242
2243         sk->sk_error_report(sk);
2244         return err;
2245 }
2246 EXPORT_SYMBOL(tcp_disconnect);
2247
2248 static inline bool tcp_can_repair_sock(const struct sock *sk)
2249 {
2250         return capable(CAP_NET_ADMIN) &&
2251                 ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_ESTABLISHED));
2252 }
2253
2254 static int tcp_repair_options_est(struct tcp_sock *tp,
2255                 struct tcp_repair_opt __user *optbuf, unsigned int len)
2256 {
2257         struct tcp_repair_opt opt;
2258
2259         while (len >= sizeof(opt)) {
2260                 if (copy_from_user(&opt, optbuf, sizeof(opt)))
2261                         return -EFAULT;
2262
2263                 optbuf++;
2264                 len -= sizeof(opt);
2265
2266                 switch (opt.opt_code) {
2267                 case TCPOPT_MSS:
2268                         tp->rx_opt.mss_clamp = opt.opt_val;
2269                         break;
2270                 case TCPOPT_WINDOW:
2271                         if (opt.opt_val > 14)
2272                                 return -EFBIG;
2273
2274                         tp->rx_opt.snd_wscale = opt.opt_val;
2275                         break;
2276                 case TCPOPT_SACK_PERM:
2277                         if (opt.opt_val != 0)
2278                                 return -EINVAL;
2279
2280                         tp->rx_opt.sack_ok |= TCP_SACK_SEEN;
2281                         if (sysctl_tcp_fack)
2282                                 tcp_enable_fack(tp);
2283                         break;
2284                 case TCPOPT_TIMESTAMP:
2285                         if (opt.opt_val != 0)
2286                                 return -EINVAL;
2287
2288                         tp->rx_opt.tstamp_ok = 1;
2289                         break;
2290                 }
2291         }
2292
2293         return 0;
2294 }
2295
2296 /*
2297  *      Socket option code for TCP.
2298  */
2299 static int do_tcp_setsockopt(struct sock *sk, int level,
2300                 int optname, char __user *optval, unsigned int optlen)
2301 {
2302         struct tcp_sock *tp = tcp_sk(sk);
2303         struct inet_connection_sock *icsk = inet_csk(sk);
2304         int val;
2305         int err = 0;
2306
2307         /* These are data/string values, all the others are ints */
2308         switch (optname) {
2309         case TCP_CONGESTION: {
2310                 char name[TCP_CA_NAME_MAX];
2311
2312                 if (optlen < 1)
2313                         return -EINVAL;
2314
2315                 val = strncpy_from_user(name, optval,
2316                                         min_t(long, TCP_CA_NAME_MAX-1, optlen));
2317                 if (val < 0)
2318                         return -EFAULT;
2319                 name[val] = 0;
2320
2321                 lock_sock(sk);
2322                 err = tcp_set_congestion_control(sk, name);
2323                 release_sock(sk);
2324                 return err;
2325         }
2326         case TCP_COOKIE_TRANSACTIONS: {
2327                 struct tcp_cookie_transactions ctd;
2328                 struct tcp_cookie_values *cvp = NULL;
2329
2330                 if (sizeof(ctd) > optlen)
2331                         return -EINVAL;
2332                 if (copy_from_user(&ctd, optval, sizeof(ctd)))
2333                         return -EFAULT;
2334
2335                 if (ctd.tcpct_used > sizeof(ctd.tcpct_value) ||
2336                     ctd.tcpct_s_data_desired > TCP_MSS_DESIRED)
2337                         return -EINVAL;
2338
2339                 if (ctd.tcpct_cookie_desired == 0) {
2340                         /* default to global value */
2341                 } else if ((0x1 & ctd.tcpct_cookie_desired) ||
2342                            ctd.tcpct_cookie_desired > TCP_COOKIE_MAX ||
2343                            ctd.tcpct_cookie_desired < TCP_COOKIE_MIN) {
2344                         return -EINVAL;
2345                 }
2346
2347                 if (TCP_COOKIE_OUT_NEVER & ctd.tcpct_flags) {
2348                         /* Supercedes all other values */
2349                         lock_sock(sk);
2350                         if (tp->cookie_values != NULL) {
2351                                 kref_put(&tp->cookie_values->kref,
2352                                          tcp_cookie_values_release);
2353                                 tp->cookie_values = NULL;
2354                         }
2355                         tp->rx_opt.cookie_in_always = 0; /* false */
2356                         tp->rx_opt.cookie_out_never = 1; /* true */
2357                         release_sock(sk);
2358                         return err;
2359                 }
2360
2361                 /* Allocate ancillary memory before locking.
2362                  */
2363                 if (ctd.tcpct_used > 0 ||
2364                     (tp->cookie_values == NULL &&
2365                      (sysctl_tcp_cookie_size > 0 ||
2366                       ctd.tcpct_cookie_desired > 0 ||
2367                       ctd.tcpct_s_data_desired > 0))) {
2368                         cvp = kzalloc(sizeof(*cvp) + ctd.tcpct_used,
2369                                       GFP_KERNEL);
2370                         if (cvp == NULL)
2371                                 return -ENOMEM;
2372
2373                         kref_init(&cvp->kref);
2374                 }
2375                 lock_sock(sk);
2376                 tp->rx_opt.cookie_in_always =
2377                         (TCP_COOKIE_IN_ALWAYS & ctd.tcpct_flags);
2378                 tp->rx_opt.cookie_out_never = 0; /* false */
2379
2380                 if (tp->cookie_values != NULL) {
2381                         if (cvp != NULL) {
2382                                 /* Changed values are recorded by a changed
2383                                  * pointer, ensuring the cookie will differ,
2384                                  * without separately hashing each value later.
2385                                  */
2386                                 kref_put(&tp->cookie_values->kref,
2387                                          tcp_cookie_values_release);
2388                         } else {
2389                                 cvp = tp->cookie_values;
2390                         }
2391                 }
2392
2393                 if (cvp != NULL) {
2394                         cvp->cookie_desired = ctd.tcpct_cookie_desired;
2395
2396                         if (ctd.tcpct_used > 0) {
2397                                 memcpy(cvp->s_data_payload, ctd.tcpct_value,
2398                                        ctd.tcpct_used);
2399                                 cvp->s_data_desired = ctd.tcpct_used;
2400                                 cvp->s_data_constant = 1; /* true */
2401                         } else {
2402                                 /* No constant payload data. */
2403                                 cvp->s_data_desired = ctd.tcpct_s_data_desired;
2404                                 cvp->s_data_constant = 0; /* false */
2405                         }
2406
2407                         tp->cookie_values = cvp;
2408                 }
2409                 release_sock(sk);
2410                 return err;
2411         }
2412         default:
2413                 /* fallthru */
2414                 break;
2415         }
2416
2417         if (optlen < sizeof(int))
2418                 return -EINVAL;
2419
2420         if (get_user(val, (int __user *)optval))
2421                 return -EFAULT;
2422
2423         lock_sock(sk);
2424
2425         switch (optname) {
2426         case TCP_MAXSEG:
2427                 /* Values greater than interface MTU won't take effect. However
2428                  * at the point when this call is done we typically don't yet
2429                  * know which interface is going to be used */
2430                 if (val < TCP_MIN_MSS || val > MAX_TCP_WINDOW) {
2431                         err = -EINVAL;
2432                         break;
2433                 }
2434                 tp->rx_opt.user_mss = val;
2435                 break;
2436
2437         case TCP_NODELAY:
2438                 if (val) {
2439                         /* TCP_NODELAY is weaker than TCP_CORK, so that
2440                          * this option on corked socket is remembered, but
2441                          * it is not activated until cork is cleared.
2442                          *
2443                          * However, when TCP_NODELAY is set we make
2444                          * an explicit push, which overrides even TCP_CORK
2445                          * for currently queued segments.
2446                          */
2447                         tp->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
2448                         tcp_push_pending_frames(sk);
2449                 } else {
2450                         tp->nonagle &= ~TCP_NAGLE_OFF;
2451                 }
2452                 break;
2453
2454         case TCP_THIN_LINEAR_TIMEOUTS:
2455                 if (val < 0 || val > 1)
2456                         err = -EINVAL;
2457                 else
2458                         tp->thin_lto = val;
2459                 break;
2460
2461         case TCP_THIN_DUPACK:
2462                 if (val < 0 || val > 1)
2463                         err = -EINVAL;
2464                 else
2465                         tp->thin_dupack = val;
2466                         if (tp->thin_dupack)
2467                                 tcp_disable_early_retrans(tp);
2468                 break;
2469
2470         case TCP_REPAIR:
2471                 if (!tcp_can_repair_sock(sk))
2472                         err = -EPERM;
2473                 else if (val == 1) {
2474                         tp->repair = 1;
2475                         sk->sk_reuse = SK_FORCE_REUSE;
2476                         tp->repair_queue = TCP_NO_QUEUE;
2477                 } else if (val == 0) {
2478                         tp->repair = 0;
2479                         sk->sk_reuse = SK_NO_REUSE;
2480                         tcp_send_window_probe(sk);
2481                 } else
2482                         err = -EINVAL;
2483
2484                 break;
2485
2486         case TCP_REPAIR_QUEUE:
2487                 if (!tp->repair)
2488                         err = -EPERM;
2489                 else if (val < TCP_QUEUES_NR)
2490                         tp->repair_queue = val;
2491                 else
2492                         err = -EINVAL;
2493                 break;
2494
2495         case TCP_QUEUE_SEQ:
2496                 if (sk->sk_state != TCP_CLOSE)
2497                         err = -EPERM;
2498                 else if (tp->repair_queue == TCP_SEND_QUEUE)
2499                         tp->write_seq = val;
2500                 else if (tp->repair_queue == TCP_RECV_QUEUE)
2501                         tp->rcv_nxt = val;
2502                 else
2503                         err = -EINVAL;
2504                 break;
2505
2506         case TCP_REPAIR_OPTIONS:
2507                 if (!tp->repair)
2508                         err = -EINVAL;
2509                 else if (sk->sk_state == TCP_ESTABLISHED)
2510                         err = tcp_repair_options_est(tp,
2511                                         (struct tcp_repair_opt __user *)optval,
2512                                         optlen);
2513                 else
2514                         err = -EPERM;
2515                 break;
2516
2517         case TCP_CORK:
2518                 /* When set indicates to always queue non-full frames.
2519                  * Later the user clears this option and we transmit
2520                  * any pending partial frames in the queue.  This is
2521                  * meant to be used alongside sendfile() to get properly
2522                  * filled frames when the user (for example) must write
2523                  * out headers with a write() call first and then use
2524                  * sendfile to send out the data parts.
2525                  *
2526                  * TCP_CORK can be set together with TCP_NODELAY and it is
2527                  * stronger than TCP_NODELAY.
2528                  */
2529                 if (val) {
2530                         tp->nonagle |= TCP_NAGLE_CORK;
2531                 } else {
2532                         tp->nonagle &= ~TCP_NAGLE_CORK;
2533                         if (tp->nonagle&TCP_NAGLE_OFF)
2534                                 tp->nonagle |= TCP_NAGLE_PUSH;
2535                         tcp_push_pending_frames(sk);
2536                 }
2537                 break;
2538
2539         case TCP_KEEPIDLE:
2540                 if (val < 1 || val > MAX_TCP_KEEPIDLE)
2541                         err = -EINVAL;
2542                 else {
2543                         tp->keepalive_time = val * HZ;
2544                         if (sock_flag(sk, SOCK_KEEPOPEN) &&
2545                             !((1 << sk->sk_state) &
2546                               (TCPF_CLOSE | TCPF_LISTEN))) {
2547                                 u32 elapsed = keepalive_time_elapsed(tp);
2548                                 if (tp->keepalive_time > elapsed)
2549                                         elapsed = tp->keepalive_time - elapsed;
2550                                 else
2551                                         elapsed = 0;
2552                                 inet_csk_reset_keepalive_timer(sk, elapsed);
2553                         }
2554                 }
2555                 break;
2556         case TCP_KEEPINTVL:
2557                 if (val < 1 || val > MAX_TCP_KEEPINTVL)
2558                         err = -EINVAL;
2559                 else
2560                         tp->keepalive_intvl = val * HZ;
2561                 break;
2562         case TCP_KEEPCNT:
2563                 if (val < 1 || val > MAX_TCP_KEEPCNT)
2564                         err = -EINVAL;
2565                 else
2566                         tp->keepalive_probes = val;
2567                 break;
2568         case TCP_SYNCNT:
2569                 if (val < 1 || val > MAX_TCP_SYNCNT)
2570                         err = -EINVAL;
2571                 else
2572                         icsk->icsk_syn_retries = val;
2573                 break;
2574
2575         case TCP_LINGER2:
2576                 if (val < 0)
2577                         tp->linger2 = -1;
2578                 else if (val > sysctl_tcp_fin_timeout / HZ)
2579                         tp->linger2 = 0;
2580                 else
2581                         tp->linger2 = val * HZ;
2582                 break;
2583
2584         case TCP_DEFER_ACCEPT:
2585                 /* Translate value in seconds to number of retransmits */
2586                 icsk->icsk_accept_queue.rskq_defer_accept =
2587                         secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,
2588                                         TCP_RTO_MAX / HZ);
2589                 break;
2590
2591         case TCP_WINDOW_CLAMP:
2592                 if (!val) {
2593                         if (sk->sk_state != TCP_CLOSE) {
2594                                 err = -EINVAL;
2595                                 break;
2596                         }
2597                         tp->window_clamp = 0;
2598                 } else
2599                         tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
2600                                                 SOCK_MIN_RCVBUF / 2 : val;
2601                 break;
2602
2603         case TCP_QUICKACK:
2604                 if (!val) {
2605                         icsk->icsk_ack.pingpong = 1;
2606                 } else {
2607                         icsk->icsk_ack.pingpong = 0;
2608                         if ((1 << sk->sk_state) &
2609                             (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
2610                             inet_csk_ack_scheduled(sk)) {
2611                                 icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
2612                                 tcp_cleanup_rbuf(sk, 1);
2613                                 if (!(val & 1))
2614                                         icsk->icsk_ack.pingpong = 1;
2615                         }
2616                 }
2617                 break;
2618
2619 #ifdef CONFIG_TCP_MD5SIG
2620         case TCP_MD5SIG:
2621                 /* Read the IP->Key mappings from userspace */
2622                 err = tp->af_specific->md5_parse(sk, optval, optlen);
2623                 break;
2624 #endif
2625         case TCP_USER_TIMEOUT:
2626                 /* Cap the max timeout in ms TCP will retry/retrans
2627                  * before giving up and aborting (ETIMEDOUT) a connection.
2628                  */
2629                 icsk->icsk_user_timeout = msecs_to_jiffies(val);
2630                 break;
2631         default:
2632                 err = -ENOPROTOOPT;
2633                 break;
2634         }
2635
2636         release_sock(sk);
2637         return err;
2638 }
2639
2640 int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
2641                    unsigned int optlen)
2642 {
2643         const struct inet_connection_sock *icsk = inet_csk(sk);
2644
2645         if (level != SOL_TCP)
2646                 return icsk->icsk_af_ops->setsockopt(sk, level, optname,
2647                                                      optval, optlen);
2648         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2649 }
2650 EXPORT_SYMBOL(tcp_setsockopt);
2651
2652 #ifdef CONFIG_COMPAT
2653 int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
2654                           char __user *optval, unsigned int optlen)
2655 {
2656         if (level != SOL_TCP)
2657                 return inet_csk_compat_setsockopt(sk, level, optname,
2658                                                   optval, optlen);
2659         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2660 }
2661 EXPORT_SYMBOL(compat_tcp_setsockopt);
2662 #endif
2663
2664 /* Return information about state of tcp endpoint in API format. */
2665 void tcp_get_info(const struct sock *sk, struct tcp_info *info)
2666 {
2667         const struct tcp_sock *tp = tcp_sk(sk);
2668         const struct inet_connection_sock *icsk = inet_csk(sk);
2669         u32 now = tcp_time_stamp;
2670
2671         memset(info, 0, sizeof(*info));
2672
2673         info->tcpi_state = sk->sk_state;
2674         info->tcpi_ca_state = icsk->icsk_ca_state;
2675         info->tcpi_retransmits = icsk->icsk_retransmits;
2676         info->tcpi_probes = icsk->icsk_probes_out;
2677         info->tcpi_backoff = icsk->icsk_backoff;
2678
2679         if (tp->rx_opt.tstamp_ok)
2680                 info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
2681         if (tcp_is_sack(tp))
2682                 info->tcpi_options |= TCPI_OPT_SACK;
2683         if (tp->rx_opt.wscale_ok) {
2684                 info->tcpi_options |= TCPI_OPT_WSCALE;
2685                 info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
2686                 info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
2687         }
2688
2689         if (tp->ecn_flags & TCP_ECN_OK)
2690                 info->tcpi_options |= TCPI_OPT_ECN;
2691         if (tp->ecn_flags & TCP_ECN_SEEN)
2692                 info->tcpi_options |= TCPI_OPT_ECN_SEEN;
2693
2694         info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
2695         info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
2696         info->tcpi_snd_mss = tp->mss_cache;
2697         info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
2698
2699         if (sk->sk_state == TCP_LISTEN) {
2700                 info->tcpi_unacked = sk->sk_ack_backlog;
2701                 info->tcpi_sacked = sk->sk_max_ack_backlog;
2702         } else {
2703                 info->tcpi_unacked = tp->packets_out;
2704                 info->tcpi_sacked = tp->sacked_out;
2705         }
2706         info->tcpi_lost = tp->lost_out;
2707         info->tcpi_retrans = tp->retrans_out;
2708         info->tcpi_fackets = tp->fackets_out;
2709
2710         info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
2711         info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
2712         info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
2713
2714         info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
2715         info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
2716         info->tcpi_rtt = jiffies_to_usecs(tp->srtt)>>3;
2717         info->tcpi_rttvar = jiffies_to_usecs(tp->mdev)>>2;
2718         info->tcpi_snd_ssthresh = tp->snd_ssthresh;
2719         info->tcpi_snd_cwnd = tp->snd_cwnd;
2720         info->tcpi_advmss = tp->advmss;
2721         info->tcpi_reordering = tp->reordering;
2722
2723         info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3;
2724         info->tcpi_rcv_space = tp->rcvq_space.space;
2725
2726         info->tcpi_total_retrans = tp->total_retrans;
2727 }
2728 EXPORT_SYMBOL_GPL(tcp_get_info);
2729
2730 static int do_tcp_getsockopt(struct sock *sk, int level,
2731                 int optname, char __user *optval, int __user *optlen)
2732 {
2733         struct inet_connection_sock *icsk = inet_csk(sk);
2734         struct tcp_sock *tp = tcp_sk(sk);
2735         int val, len;
2736
2737         if (get_user(len, optlen))
2738                 return -EFAULT;
2739
2740         len = min_t(unsigned int, len, sizeof(int));
2741
2742         if (len < 0)
2743                 return -EINVAL;
2744
2745         switch (optname) {
2746         case TCP_MAXSEG:
2747                 val = tp->mss_cache;
2748                 if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
2749                         val = tp->rx_opt.user_mss;
2750                 if (tp->repair)
2751                         val = tp->rx_opt.mss_clamp;
2752                 break;
2753         case TCP_NODELAY:
2754                 val = !!(tp->nonagle&TCP_NAGLE_OFF);
2755                 break;
2756         case TCP_CORK:
2757                 val = !!(tp->nonagle&TCP_NAGLE_CORK);
2758                 break;
2759         case TCP_KEEPIDLE:
2760                 val = keepalive_time_when(tp) / HZ;
2761                 break;
2762         case TCP_KEEPINTVL:
2763                 val = keepalive_intvl_when(tp) / HZ;
2764                 break;
2765         case TCP_KEEPCNT:
2766                 val = keepalive_probes(tp);
2767                 break;
2768         case TCP_SYNCNT:
2769                 val = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
2770                 break;
2771         case TCP_LINGER2:
2772                 val = tp->linger2;
2773                 if (val >= 0)
2774                         val = (val ? : sysctl_tcp_fin_timeout) / HZ;
2775                 break;
2776         case TCP_DEFER_ACCEPT:
2777                 val = retrans_to_secs(icsk->icsk_accept_queue.rskq_defer_accept,
2778                                       TCP_TIMEOUT_INIT / HZ, TCP_RTO_MAX / HZ);
2779                 break;
2780         case TCP_WINDOW_CLAMP:
2781                 val = tp->window_clamp;
2782                 break;
2783         case TCP_INFO: {
2784                 struct tcp_info info;
2785
2786                 if (get_user(len, optlen))
2787                         return -EFAULT;
2788
2789                 tcp_get_info(sk, &info);
2790
2791                 len = min_t(unsigned int, len, sizeof(info));
2792                 if (put_user(len, optlen))
2793                         return -EFAULT;
2794                 if (copy_to_user(optval, &info, len))
2795                         return -EFAULT;
2796                 return 0;
2797         }
2798         case TCP_QUICKACK:
2799                 val = !icsk->icsk_ack.pingpong;
2800                 break;
2801
2802         case TCP_CONGESTION:
2803                 if (get_user(len, optlen))
2804                         return -EFAULT;
2805                 len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
2806                 if (put_user(len, optlen))
2807                         return -EFAULT;
2808                 if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
2809                         return -EFAULT;
2810                 return 0;
2811
2812         case TCP_COOKIE_TRANSACTIONS: {
2813                 struct tcp_cookie_transactions ctd;
2814                 struct tcp_cookie_values *cvp = tp->cookie_values;
2815
2816                 if (get_user(len, optlen))
2817                         return -EFAULT;
2818                 if (len < sizeof(ctd))
2819                         return -EINVAL;
2820
2821                 memset(&ctd, 0, sizeof(ctd));
2822                 ctd.tcpct_flags = (tp->rx_opt.cookie_in_always ?
2823                                    TCP_COOKIE_IN_ALWAYS : 0)
2824                                 | (tp->rx_opt.cookie_out_never ?
2825                                    TCP_COOKIE_OUT_NEVER : 0);
2826
2827                 if (cvp != NULL) {
2828                         ctd.tcpct_flags |= (cvp->s_data_in ?
2829                                             TCP_S_DATA_IN : 0)
2830                                          | (cvp->s_data_out ?
2831                                             TCP_S_DATA_OUT : 0);
2832
2833                         ctd.tcpct_cookie_desired = cvp->cookie_desired;
2834                         ctd.tcpct_s_data_desired = cvp->s_data_desired;
2835
2836                         memcpy(&ctd.tcpct_value[0], &cvp->cookie_pair[0],
2837                                cvp->cookie_pair_size);
2838                         ctd.tcpct_used = cvp->cookie_pair_size;
2839                 }
2840
2841                 if (put_user(sizeof(ctd), optlen))
2842                         return -EFAULT;
2843                 if (copy_to_user(optval, &ctd, sizeof(ctd)))
2844                         return -EFAULT;
2845                 return 0;
2846         }
2847         case TCP_THIN_LINEAR_TIMEOUTS:
2848                 val = tp->thin_lto;
2849                 break;
2850         case TCP_THIN_DUPACK:
2851                 val = tp->thin_dupack;
2852                 break;
2853
2854         case TCP_REPAIR:
2855                 val = tp->repair;
2856                 break;
2857
2858         case TCP_REPAIR_QUEUE:
2859                 if (tp->repair)
2860                         val = tp->repair_queue;
2861                 else
2862                         return -EINVAL;
2863                 break;
2864
2865         case TCP_QUEUE_SEQ:
2866                 if (tp->repair_queue == TCP_SEND_QUEUE)
2867                         val = tp->write_seq;
2868                 else if (tp->repair_queue == TCP_RECV_QUEUE)
2869                         val = tp->rcv_nxt;
2870                 else
2871                         return -EINVAL;
2872                 break;
2873
2874         case TCP_USER_TIMEOUT:
2875                 val = jiffies_to_msecs(icsk->icsk_user_timeout);
2876                 break;
2877         default:
2878                 return -ENOPROTOOPT;
2879         }
2880
2881         if (put_user(len, optlen))
2882                 return -EFAULT;
2883         if (copy_to_user(optval, &val, len))
2884                 return -EFAULT;
2885         return 0;
2886 }
2887
2888 int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
2889                    int __user *optlen)
2890 {
2891         struct inet_connection_sock *icsk = inet_csk(sk);
2892
2893         if (level != SOL_TCP)
2894                 return icsk->icsk_af_ops->getsockopt(sk, level, optname,
2895                                                      optval, optlen);
2896         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2897 }
2898 EXPORT_SYMBOL(tcp_getsockopt);
2899
2900 #ifdef CONFIG_COMPAT
2901 int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
2902                           char __user *optval, int __user *optlen)
2903 {
2904         if (level != SOL_TCP)
2905                 return inet_csk_compat_getsockopt(sk, level, optname,
2906                                                   optval, optlen);
2907         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2908 }
2909 EXPORT_SYMBOL(compat_tcp_getsockopt);
2910 #endif
2911
2912 struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
2913         netdev_features_t features)
2914 {
2915         struct sk_buff *segs = ERR_PTR(-EINVAL);
2916         struct tcphdr *th;
2917         unsigned int thlen;
2918         unsigned int seq;
2919         __be32 delta;
2920         unsigned int oldlen;
2921         unsigned int mss;
2922
2923         if (!pskb_may_pull(skb, sizeof(*th)))
2924                 goto out;
2925
2926         th = tcp_hdr(skb);
2927         thlen = th->doff * 4;
2928         if (thlen < sizeof(*th))
2929                 goto out;
2930
2931         if (!pskb_may_pull(skb, thlen))
2932                 goto out;
2933
2934         oldlen = (u16)~skb->len;
2935         __skb_pull(skb, thlen);
2936
2937         mss = skb_shinfo(skb)->gso_size;
2938         if (unlikely(skb->len <= mss))
2939                 goto out;
2940
2941         if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
2942                 /* Packet is from an untrusted source, reset gso_segs. */
2943                 int type = skb_shinfo(skb)->gso_type;
2944
2945                 if (unlikely(type &
2946                              ~(SKB_GSO_TCPV4 |
2947                                SKB_GSO_DODGY |
2948                                SKB_GSO_TCP_ECN |
2949                                SKB_GSO_TCPV6 |
2950                                0) ||
2951                              !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))))
2952                         goto out;
2953
2954                 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
2955
2956                 segs = NULL;
2957                 goto out;
2958         }
2959
2960         segs = skb_segment(skb, features);
2961         if (IS_ERR(segs))
2962                 goto out;
2963
2964         delta = htonl(oldlen + (thlen + mss));
2965
2966         skb = segs;
2967         th = tcp_hdr(skb);
2968         seq = ntohl(th->seq);
2969
2970         do {
2971                 th->fin = th->psh = 0;
2972
2973                 th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
2974                                        (__force u32)delta));
2975                 if (skb->ip_summed != CHECKSUM_PARTIAL)
2976                         th->check =
2977                              csum_fold(csum_partial(skb_transport_header(skb),
2978                                                     thlen, skb->csum));
2979
2980                 seq += mss;
2981                 skb = skb->next;
2982                 th = tcp_hdr(skb);
2983
2984                 th->seq = htonl(seq);
2985                 th->cwr = 0;
2986         } while (skb->next);
2987
2988         delta = htonl(oldlen + (skb->tail - skb->transport_header) +
2989                       skb->data_len);
2990         th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
2991                                 (__force u32)delta));
2992         if (skb->ip_summed != CHECKSUM_PARTIAL)
2993                 th->check = csum_fold(csum_partial(skb_transport_header(skb),
2994                                                    thlen, skb->csum));
2995
2996 out:
2997         return segs;
2998 }
2999 EXPORT_SYMBOL(tcp_tso_segment);
3000
3001 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
3002 {
3003         struct sk_buff **pp = NULL;
3004         struct sk_buff *p;
3005         struct tcphdr *th;
3006         struct tcphdr *th2;
3007         unsigned int len;
3008         unsigned int thlen;
3009         __be32 flags;
3010         unsigned int mss = 1;
3011         unsigned int hlen;
3012         unsigned int off;
3013         int flush = 1;
3014         int i;
3015
3016         off = skb_gro_offset(skb);
3017         hlen = off + sizeof(*th);
3018         th = skb_gro_header_fast(skb, off);
3019         if (skb_gro_header_hard(skb, hlen)) {
3020                 th = skb_gro_header_slow(skb, hlen, off);
3021                 if (unlikely(!th))
3022                         goto out;
3023         }
3024
3025         thlen = th->doff * 4;
3026         if (thlen < sizeof(*th))
3027                 goto out;
3028
3029         hlen = off + thlen;
3030         if (skb_gro_header_hard(skb, hlen)) {
3031                 th = skb_gro_header_slow(skb, hlen, off);
3032                 if (unlikely(!th))
3033                         goto out;
3034         }
3035
3036         skb_gro_pull(skb, thlen);
3037
3038         len = skb_gro_len(skb);
3039         flags = tcp_flag_word(th);
3040
3041         for (; (p = *head); head = &p->next) {
3042                 if (!NAPI_GRO_CB(p)->same_flow)
3043                         continue;
3044
3045                 th2 = tcp_hdr(p);
3046
3047                 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
3048                         NAPI_GRO_CB(p)->same_flow = 0;
3049                         continue;
3050                 }
3051
3052                 goto found;
3053         }
3054
3055         goto out_check_final;
3056
3057 found:
3058         flush = NAPI_GRO_CB(p)->flush;
3059         flush |= (__force int)(flags & TCP_FLAG_CWR);
3060         flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
3061                   ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
3062         flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
3063         for (i = sizeof(*th); i < thlen; i += 4)
3064                 flush |= *(u32 *)((u8 *)th + i) ^
3065                          *(u32 *)((u8 *)th2 + i);
3066
3067         mss = skb_shinfo(p)->gso_size;
3068
3069         flush |= (len - 1) >= mss;
3070         flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
3071
3072         if (flush || skb_gro_receive(head, skb)) {
3073                 mss = 1;
3074                 goto out_check_final;
3075         }
3076
3077         p = *head;
3078         th2 = tcp_hdr(p);
3079         tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);
3080
3081 out_check_final:
3082         flush = len < mss;
3083         flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH |
3084                                         TCP_FLAG_RST | TCP_FLAG_SYN |
3085                                         TCP_FLAG_FIN));
3086
3087         if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
3088                 pp = head;
3089
3090 out:
3091         NAPI_GRO_CB(skb)->flush |= flush;
3092
3093         return pp;
3094 }
3095 EXPORT_SYMBOL(tcp_gro_receive);
3096
3097 int tcp_gro_complete(struct sk_buff *skb)
3098 {
3099         struct tcphdr *th = tcp_hdr(skb);
3100
3101         skb->csum_start = skb_transport_header(skb) - skb->head;
3102         skb->csum_offset = offsetof(struct tcphdr, check);
3103         skb->ip_summed = CHECKSUM_PARTIAL;
3104
3105         skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
3106
3107         if (th->cwr)
3108                 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
3109
3110         return 0;
3111 }
3112 EXPORT_SYMBOL(tcp_gro_complete);
3113
3114 #ifdef CONFIG_TCP_MD5SIG
3115 static unsigned long tcp_md5sig_users;
3116 static struct tcp_md5sig_pool __percpu *tcp_md5sig_pool;
3117 static DEFINE_SPINLOCK(tcp_md5sig_pool_lock);
3118
3119 static void __tcp_free_md5sig_pool(struct tcp_md5sig_pool __percpu *pool)
3120 {
3121         int cpu;
3122
3123         for_each_possible_cpu(cpu) {
3124                 struct tcp_md5sig_pool *p = per_cpu_ptr(pool, cpu);
3125
3126                 if (p->md5_desc.tfm)
3127                         crypto_free_hash(p->md5_desc.tfm);
3128         }
3129         free_percpu(pool);
3130 }
3131
3132 void tcp_free_md5sig_pool(void)
3133 {
3134         struct tcp_md5sig_pool __percpu *pool = NULL;
3135
3136         spin_lock_bh(&tcp_md5sig_pool_lock);
3137         if (--tcp_md5sig_users == 0) {
3138                 pool = tcp_md5sig_pool;
3139                 tcp_md5sig_pool = NULL;
3140         }
3141         spin_unlock_bh(&tcp_md5sig_pool_lock);
3142         if (pool)
3143                 __tcp_free_md5sig_pool(pool);
3144 }
3145 EXPORT_SYMBOL(tcp_free_md5sig_pool);
3146
3147 static struct tcp_md5sig_pool __percpu *
3148 __tcp_alloc_md5sig_pool(struct sock *sk)
3149 {
3150         int cpu;
3151         struct tcp_md5sig_pool __percpu *pool;
3152
3153         pool = alloc_percpu(struct tcp_md5sig_pool);
3154         if (!pool)
3155                 return NULL;
3156
3157         for_each_possible_cpu(cpu) {
3158                 struct crypto_hash *hash;
3159
3160                 hash = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
3161                 if (!hash || IS_ERR(hash))
3162                         goto out_free;
3163
3164                 per_cpu_ptr(pool, cpu)->md5_desc.tfm = hash;
3165         }
3166         return pool;
3167 out_free:
3168         __tcp_free_md5sig_pool(pool);
3169         return NULL;
3170 }
3171
3172 struct tcp_md5sig_pool __percpu *tcp_alloc_md5sig_pool(struct sock *sk)
3173 {
3174         struct tcp_md5sig_pool __percpu *pool;
3175         bool alloc = false;
3176
3177 retry:
3178         spin_lock_bh(&tcp_md5sig_pool_lock);
3179         pool = tcp_md5sig_pool;
3180         if (tcp_md5sig_users++ == 0) {
3181                 alloc = true;
3182                 spin_unlock_bh(&tcp_md5sig_pool_lock);
3183         } else if (!pool) {
3184                 tcp_md5sig_users--;
3185                 spin_unlock_bh(&tcp_md5sig_pool_lock);
3186                 cpu_relax();
3187                 goto retry;
3188         } else
3189                 spin_unlock_bh(&tcp_md5sig_pool_lock);
3190
3191         if (alloc) {
3192                 /* we cannot hold spinlock here because this may sleep. */
3193                 struct tcp_md5sig_pool __percpu *p;
3194
3195                 p = __tcp_alloc_md5sig_pool(sk);
3196                 spin_lock_bh(&tcp_md5sig_pool_lock);
3197                 if (!p) {
3198                         tcp_md5sig_users--;
3199                         spin_unlock_bh(&tcp_md5sig_pool_lock);
3200                         return NULL;
3201                 }
3202                 pool = tcp_md5sig_pool;
3203                 if (pool) {
3204                         /* oops, it has already been assigned. */
3205                         spin_unlock_bh(&tcp_md5sig_pool_lock);
3206                         __tcp_free_md5sig_pool(p);
3207                 } else {
3208                         tcp_md5sig_pool = pool = p;
3209                         spin_unlock_bh(&tcp_md5sig_pool_lock);
3210                 }
3211         }
3212         return pool;
3213 }
3214 EXPORT_SYMBOL(tcp_alloc_md5sig_pool);
3215
3216
3217 /**
3218  *      tcp_get_md5sig_pool - get md5sig_pool for this user
3219  *
3220  *      We use percpu structure, so if we succeed, we exit with preemption
3221  *      and BH disabled, to make sure another thread or softirq handling
3222  *      wont try to get same context.
3223  */
3224 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void)
3225 {
3226         struct tcp_md5sig_pool __percpu *p;
3227
3228         local_bh_disable();
3229
3230         spin_lock(&tcp_md5sig_pool_lock);
3231         p = tcp_md5sig_pool;
3232         if (p)
3233                 tcp_md5sig_users++;
3234         spin_unlock(&tcp_md5sig_pool_lock);
3235
3236         if (p)
3237                 return this_cpu_ptr(p);
3238
3239         local_bh_enable();
3240         return NULL;
3241 }
3242 EXPORT_SYMBOL(tcp_get_md5sig_pool);
3243
3244 void tcp_put_md5sig_pool(void)
3245 {
3246         local_bh_enable();
3247         tcp_free_md5sig_pool();
3248 }
3249 EXPORT_SYMBOL(tcp_put_md5sig_pool);
3250
3251 int tcp_md5_hash_header(struct tcp_md5sig_pool *hp,
3252                         const struct tcphdr *th)
3253 {
3254         struct scatterlist sg;
3255         struct tcphdr hdr;
3256         int err;
3257
3258         /* We are not allowed to change tcphdr, make a local copy */
3259         memcpy(&hdr, th, sizeof(hdr));
3260         hdr.check = 0;
3261
3262         /* options aren't included in the hash */
3263         sg_init_one(&sg, &hdr, sizeof(hdr));
3264         err = crypto_hash_update(&hp->md5_desc, &sg, sizeof(hdr));
3265         return err;
3266 }
3267 EXPORT_SYMBOL(tcp_md5_hash_header);
3268
3269 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *hp,
3270                           const struct sk_buff *skb, unsigned int header_len)
3271 {
3272         struct scatterlist sg;
3273         const struct tcphdr *tp = tcp_hdr(skb);
3274         struct hash_desc *desc = &hp->md5_desc;
3275         unsigned int i;
3276         const unsigned int head_data_len = skb_headlen(skb) > header_len ?
3277                                            skb_headlen(skb) - header_len : 0;
3278         const struct skb_shared_info *shi = skb_shinfo(skb);
3279         struct sk_buff *frag_iter;
3280
3281         sg_init_table(&sg, 1);
3282
3283         sg_set_buf(&sg, ((u8 *) tp) + header_len, head_data_len);
3284         if (crypto_hash_update(desc, &sg, head_data_len))
3285                 return 1;
3286
3287         for (i = 0; i < shi->nr_frags; ++i) {
3288                 const struct skb_frag_struct *f = &shi->frags[i];
3289                 struct page *page = skb_frag_page(f);
3290                 sg_set_page(&sg, page, skb_frag_size(f), f->page_offset);
3291                 if (crypto_hash_update(desc, &sg, skb_frag_size(f)))
3292                         return 1;
3293         }
3294
3295         skb_walk_frags(skb, frag_iter)
3296                 if (tcp_md5_hash_skb_data(hp, frag_iter, 0))
3297                         return 1;
3298
3299         return 0;
3300 }
3301 EXPORT_SYMBOL(tcp_md5_hash_skb_data);
3302
3303 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, const struct tcp_md5sig_key *key)
3304 {
3305         struct scatterlist sg;
3306
3307         sg_init_one(&sg, key->key, key->keylen);
3308         return crypto_hash_update(&hp->md5_desc, &sg, key->keylen);
3309 }
3310 EXPORT_SYMBOL(tcp_md5_hash_key);
3311
3312 #endif
3313
3314 /**
3315  * Each Responder maintains up to two secret values concurrently for
3316  * efficient secret rollover.  Each secret value has 4 states:
3317  *
3318  * Generating.  (tcp_secret_generating != tcp_secret_primary)
3319  *    Generates new Responder-Cookies, but not yet used for primary
3320  *    verification.  This is a short-term state, typically lasting only
3321  *    one round trip time (RTT).
3322  *
3323  * Primary.  (tcp_secret_generating == tcp_secret_primary)
3324  *    Used both for generation and primary verification.
3325  *
3326  * Retiring.  (tcp_secret_retiring != tcp_secret_secondary)
3327  *    Used for verification, until the first failure that can be
3328  *    verified by the newer Generating secret.  At that time, this
3329  *    cookie's state is changed to Secondary, and the Generating
3330  *    cookie's state is changed to Primary.  This is a short-term state,
3331  *    typically lasting only one round trip time (RTT).
3332  *
3333  * Secondary.  (tcp_secret_retiring == tcp_secret_secondary)
3334  *    Used for secondary verification, after primary verification
3335  *    failures.  This state lasts no more than twice the Maximum Segment
3336  *    Lifetime (2MSL).  Then, the secret is discarded.
3337  */
3338 struct tcp_cookie_secret {
3339         /* The secret is divided into two parts.  The digest part is the
3340          * equivalent of previously hashing a secret and saving the state,
3341          * and serves as an initialization vector (IV).  The message part
3342          * serves as the trailing secret.
3343          */
3344         u32                             secrets[COOKIE_WORKSPACE_WORDS];
3345         unsigned long                   expires;
3346 };
3347
3348 #define TCP_SECRET_1MSL (HZ * TCP_PAWS_MSL)
3349 #define TCP_SECRET_2MSL (HZ * TCP_PAWS_MSL * 2)
3350 #define TCP_SECRET_LIFE (HZ * 600)
3351
3352 static struct tcp_cookie_secret tcp_secret_one;
3353 static struct tcp_cookie_secret tcp_secret_two;
3354
3355 /* Essentially a circular list, without dynamic allocation. */
3356 static struct tcp_cookie_secret *tcp_secret_generating;
3357 static struct tcp_cookie_secret *tcp_secret_primary;
3358 static struct tcp_cookie_secret *tcp_secret_retiring;
3359 static struct tcp_cookie_secret *tcp_secret_secondary;
3360
3361 static DEFINE_SPINLOCK(tcp_secret_locker);
3362
3363 /* Select a pseudo-random word in the cookie workspace.
3364  */
3365 static inline u32 tcp_cookie_work(const u32 *ws, const int n)
3366 {
3367         return ws[COOKIE_DIGEST_WORDS + ((COOKIE_MESSAGE_WORDS-1) & ws[n])];
3368 }
3369
3370 /* Fill bakery[COOKIE_WORKSPACE_WORDS] with generator, updating as needed.
3371  * Called in softirq context.
3372  * Returns: 0 for success.
3373  */
3374 int tcp_cookie_generator(u32 *bakery)
3375 {
3376         unsigned long jiffy = jiffies;
3377
3378         if (unlikely(time_after_eq(jiffy, tcp_secret_generating->expires))) {
3379                 spin_lock_bh(&tcp_secret_locker);
3380                 if (!time_after_eq(jiffy, tcp_secret_generating->expires)) {
3381                         /* refreshed by another */
3382                         memcpy(bakery,
3383                                &tcp_secret_generating->secrets[0],
3384                                COOKIE_WORKSPACE_WORDS);
3385                 } else {
3386                         /* still needs refreshing */
3387                         get_random_bytes(bakery, COOKIE_WORKSPACE_WORDS);
3388
3389                         /* The first time, paranoia assumes that the
3390                          * randomization function isn't as strong.  But,
3391                          * this secret initialization is delayed until
3392                          * the last possible moment (packet arrival).
3393                          * Although that time is observable, it is
3394                          * unpredictably variable.  Mash in the most
3395                          * volatile clock bits available, and expire the
3396                          * secret extra quickly.
3397                          */
3398                         if (unlikely(tcp_secret_primary->expires ==
3399                                      tcp_secret_secondary->expires)) {
3400                                 struct timespec tv;
3401
3402                                 getnstimeofday(&tv);
3403                                 bakery[COOKIE_DIGEST_WORDS+0] ^=
3404                                         (u32)tv.tv_nsec;
3405
3406                                 tcp_secret_secondary->expires = jiffy
3407                                         + TCP_SECRET_1MSL
3408                                         + (0x0f & tcp_cookie_work(bakery, 0));
3409                         } else {
3410                                 tcp_secret_secondary->expires = jiffy
3411                                         + TCP_SECRET_LIFE
3412                                         + (0xff & tcp_cookie_work(bakery, 1));
3413                                 tcp_secret_primary->expires = jiffy
3414                                         + TCP_SECRET_2MSL
3415                                         + (0x1f & tcp_cookie_work(bakery, 2));
3416                         }
3417                         memcpy(&tcp_secret_secondary->secrets[0],
3418                                bakery, COOKIE_WORKSPACE_WORDS);
3419
3420                         rcu_assign_pointer(tcp_secret_generating,
3421                                            tcp_secret_secondary);
3422                         rcu_assign_pointer(tcp_secret_retiring,
3423                                            tcp_secret_primary);
3424                         /*
3425                          * Neither call_rcu() nor synchronize_rcu() needed.
3426                          * Retiring data is not freed.  It is replaced after
3427                          * further (locked) pointer updates, and a quiet time
3428                          * (minimum 1MSL, maximum LIFE - 2MSL).
3429                          */
3430                 }
3431                 spin_unlock_bh(&tcp_secret_locker);
3432         } else {
3433                 rcu_read_lock_bh();
3434                 memcpy(bakery,
3435                        &rcu_dereference(tcp_secret_generating)->secrets[0],
3436                        COOKIE_WORKSPACE_WORDS);
3437                 rcu_read_unlock_bh();
3438         }
3439         return 0;
3440 }
3441 EXPORT_SYMBOL(tcp_cookie_generator);
3442
3443 void tcp_done(struct sock *sk)
3444 {
3445         if (sk->sk_state == TCP_SYN_SENT || sk->sk_state == TCP_SYN_RECV)
3446                 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_ATTEMPTFAILS);
3447
3448         tcp_set_state(sk, TCP_CLOSE);
3449         tcp_clear_xmit_timers(sk);
3450
3451         sk->sk_shutdown = SHUTDOWN_MASK;
3452
3453         if (!sock_flag(sk, SOCK_DEAD))
3454                 sk->sk_state_change(sk);
3455         else
3456                 inet_csk_destroy_sock(sk);
3457 }
3458 EXPORT_SYMBOL_GPL(tcp_done);
3459
3460 extern struct tcp_congestion_ops tcp_reno;
3461
3462 static __initdata unsigned long thash_entries;
3463 static int __init set_thash_entries(char *str)
3464 {
3465         if (!str)
3466                 return 0;
3467         thash_entries = simple_strtoul(str, &str, 0);
3468         return 1;
3469 }
3470 __setup("thash_entries=", set_thash_entries);
3471
3472 void tcp_init_mem(struct net *net)
3473 {
3474         unsigned long limit = nr_free_buffer_pages() / 8;
3475         limit = max(limit, 128UL);
3476         net->ipv4.sysctl_tcp_mem[0] = limit / 4 * 3;
3477         net->ipv4.sysctl_tcp_mem[1] = limit;
3478         net->ipv4.sysctl_tcp_mem[2] = net->ipv4.sysctl_tcp_mem[0] * 2;
3479 }
3480
3481 void __init tcp_init(void)
3482 {
3483         struct sk_buff *skb = NULL;
3484         unsigned long limit;
3485         int max_rshare, max_wshare, cnt;
3486         unsigned int i;
3487         unsigned long jiffy = jiffies;
3488
3489         BUILD_BUG_ON(sizeof(struct tcp_skb_cb) > sizeof(skb->cb));
3490
3491         percpu_counter_init(&tcp_sockets_allocated, 0);
3492         percpu_counter_init(&tcp_orphan_count, 0);
3493         tcp_hashinfo.bind_bucket_cachep =
3494                 kmem_cache_create("tcp_bind_bucket",
3495                                   sizeof(struct inet_bind_bucket), 0,
3496                                   SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
3497
3498         /* Size and allocate the main established and bind bucket
3499          * hash tables.
3500          *
3501          * The methodology is similar to that of the buffer cache.
3502          */
3503         tcp_hashinfo.ehash =
3504                 alloc_large_system_hash("TCP established",
3505                                         sizeof(struct inet_ehash_bucket),
3506                                         thash_entries,
3507                                         (totalram_pages >= 128 * 1024) ?
3508                                         13 : 15,
3509                                         0,
3510                                         NULL,
3511                                         &tcp_hashinfo.ehash_mask,
3512                                         thash_entries ? 0 : 512 * 1024);
3513         for (i = 0; i <= tcp_hashinfo.ehash_mask; i++) {
3514                 INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].chain, i);
3515                 INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].twchain, i);
3516         }
3517         if (inet_ehash_locks_alloc(&tcp_hashinfo))
3518                 panic("TCP: failed to alloc ehash_locks");
3519         tcp_hashinfo.bhash =
3520                 alloc_large_system_hash("TCP bind",
3521                                         sizeof(struct inet_bind_hashbucket),
3522                                         tcp_hashinfo.ehash_mask + 1,
3523                                         (totalram_pages >= 128 * 1024) ?
3524                                         13 : 15,
3525                                         0,
3526                                         &tcp_hashinfo.bhash_size,
3527                                         NULL,
3528                                         64 * 1024);
3529         tcp_hashinfo.bhash_size = 1U << tcp_hashinfo.bhash_size;
3530         for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
3531                 spin_lock_init(&tcp_hashinfo.bhash[i].lock);
3532                 INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
3533         }
3534
3535
3536         cnt = tcp_hashinfo.ehash_mask + 1;
3537
3538         tcp_death_row.sysctl_max_tw_buckets = cnt / 2;
3539         sysctl_tcp_max_orphans = cnt / 2;
3540         sysctl_max_syn_backlog = max(128, cnt / 256);
3541
3542         tcp_init_mem(&init_net);
3543         /* Set per-socket limits to no more than 1/128 the pressure threshold */
3544         limit = nr_free_buffer_pages() << (PAGE_SHIFT - 7);
3545         max_wshare = min(4UL*1024*1024, limit);
3546         max_rshare = min(6UL*1024*1024, limit);
3547
3548         sysctl_tcp_wmem[0] = SK_MEM_QUANTUM;
3549         sysctl_tcp_wmem[1] = 16*1024;
3550         sysctl_tcp_wmem[2] = max(64*1024, max_wshare);
3551
3552         sysctl_tcp_rmem[0] = SK_MEM_QUANTUM;
3553         sysctl_tcp_rmem[1] = 87380;
3554         sysctl_tcp_rmem[2] = max(87380, max_rshare);
3555
3556         pr_info("Hash tables configured (established %u bind %u)\n",
3557                 tcp_hashinfo.ehash_mask + 1, tcp_hashinfo.bhash_size);
3558
3559         tcp_register_congestion_control(&tcp_reno);
3560
3561         memset(&tcp_secret_one.secrets[0], 0, sizeof(tcp_secret_one.secrets));
3562         memset(&tcp_secret_two.secrets[0], 0, sizeof(tcp_secret_two.secrets));
3563         tcp_secret_one.expires = jiffy; /* past due */
3564         tcp_secret_two.expires = jiffy; /* past due */
3565         tcp_secret_generating = &tcp_secret_one;
3566         tcp_secret_primary = &tcp_secret_one;
3567         tcp_secret_retiring = &tcp_secret_two;
3568         tcp_secret_secondary = &tcp_secret_two;
3569 }