net/ipv4/tcp.c

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